TW201619320A - Anisotropic adhesive sheet - Google Patents

Abstract

The present invention relates to an adhesive sheet that firmly adheres to an adherend and that is easily peeled from the adherend when an adherend is unnecessary or when sticking is corrected, and more specifically, the present invention relates to an anisotropic adhesive sheet which has no restrictions as to the base material and the adhesive, and which has different peelability depending on the direction of peeling. The present invention is an anisotropic adhesive sheet 10 in which a resin layer 2 having an uneven structure cross-section and an adhesive layer 3 to be buried in the uneven structure of the resin layer 2 are laminated in order on at least one surface of a base material 1, wherein the pattern shape of the uneven structure of the resin layer 2 is anisotropic, and the surface of the adhesive layer has an arithmetic average surface roughness Ra of 5 [mu]m and is smooth.

Description

Anisotropic adhesive sheet

The present invention relates to an anisotropic adhesive sheet which exhibits different peeling properties depending on a peeling direction, and which can have both strong adhesiveness in a specific direction and excellent peelability in a direction other than a specific direction.

Adhesive products such as adhesive sheets and adhesive tapes are used in various applications. Usually, depending on the intended use, an adhesive with a suitable adhesive strength is selected. In addition, in the case of permanent bonding, an adhesive having a strong adhesive force is usually used, and in a re-peelable application, an adhesive having a weak adhesive force is used. However, in adhesive products such as wallpapers, window films (films for window glass), and marker sheets, adhesives having strong adhesion are required, but when the adhesive position is corrected, bubbles or foreign matter enters during bonding, and re-adhesive of adhesive products are adhered. At the same time, it is also required to satisfy the opposite function that is desired to be easily peeled off. In addition, when the decorative seal, the seal, and the various adhesive tapes are removed when they are not needed, there is a problem that the adhesive remains on the adherend. Further, a packaging container such as a corrugated cardboard box or an envelope to which a recipient address label, a delivery note for a home delivery, or the like is pasted is usually discarded directly by adhering to a recipient address label or the like. However, in order to prevent the leakage of personal information and the like, it is required to simply peel off the portion in which the personal information such as the address tag of the recipient is described, and then the packaging container such as a corrugated cardboard box is discarded.

On the other hand, for protective films, metal sheets or steels for optical films or displays. A protective sheet for a sheet or the like is required to be used without being peeled off when it is attached to an adherend, and can be easily peeled off from the adherend when it is not needed (light peeling). That is, in the use of permanent bonding and in the application capable of re-peeling, an adhesive product is expected which is firmly adhered to the adherend, and can be easily removed from the adherend when the adherend is not needed and the fitting is corrected. Adhesive product peeled off by the adherend.

Various proposals have been made in the past for both adhesiveness and peelability. For example, Patent Document 1 proposes a heat-peelable adhesive sheet in which an adhesive layer containing a foaming agent is provided on a substrate, and the adhesive force is lowered or lost under heat treatment. Further, Patent Document 2 proposes an adhesive tape in which the adhesive is cured by radiation irradiation, and the adhesive force is remarkably lowered. However, when an ultraviolet irradiation device or a heating device is not provided, such an adhesive sheet has a problem that the peeling function cannot be utilized.

In addition, several adhesive sheets having different adhesion forces depending on the peeling direction have been proposed. For example, Patent Document 3 proposes a pressure-sensitive adhesive product in which a partially oriented and crystallized elastomer is used. Patent Document 4 describes an anisotropic releasable adhesive tape in which an anisotropically shaped rigid body particle and/or fiber is oriented and dispersed in at least one layer of a substrate and/or an adhesive layer. These solutions do not require an apparatus or device for utilizing an easy peeling function, and are excellent in workability, but the material of the adhesive is limited to a specific substance, and thus there is a problem that the range of characteristics of the adhesive is limited.

Further, Patent Document 5 proposes an anisotropically adhesive molded article in which a support having anisotropic flexibility is used. By using a support having anisotropic flexibility, the material of the adhesive itself is no longer limited to a specific substance, and therefore there is an advantage that the range of characteristics of the adhesive is not limited. On the other hand, however, there is a problem that limits the structure of the support.

[Previous Technical Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 50-013878

[Patent Document 2] JP-A-60-196956

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2000-502379

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2004-189847

[Patent Document 5] Japanese Patent Laid-Open No. Hei 7-018227

The present invention has been made in view of the above circumstances, and the present invention can provide an adhesive sheet which can be firmly adhered to an adherend and which can be easily peeled off from an adherend when it is not required or bonded.

More specifically, an object of the present invention is to provide an anisotropic adhesive sheet which exhibits different peeling properties depending on a peeling direction, and can have a firm adhesiveness in a specific direction and a direction other than a specific direction. Excellent peelability.

In order to solve this problem, it has been found that by providing a resin layer between the substrate and the adhesive layer, a concave-convex structure is provided on the surface of the resin layer in contact with the adhesive layer, and the adhesive force of the adhesive sheet changes. Further, it has been found that an adhesive sheet having a different peeling force (adhesion) depending on the peeling direction can be produced by making the pattern of the uneven structure on the surface of the resin layer anisotropic, and the present invention has been completed.

In order to solve the above problems, the present invention provides an anisotropic adhesive sheet which is a resin layer in which a cross section having a concavo-convex structure is laminated on at least one surface of a substrate, and an adhesive layer in which the uneven structure of the resin layer is filled. In the adhesive sheet, the pattern shape of the uneven structure of the resin layer has anisotropy, and the surface of the adhesive layer has smoothness, and the arithmetic mean surface roughness Ra is 5 μm or less.

Further, an anisotropic adhesive sheet is provided in which the ratio K of the thickness T1 of the thinnest portion of the thickness of the adhesive layer to the thickness T2 of the thickest portion is K = T1/T2 = 0.2 to 0.8.

Further, an anisotropic adhesive sheet in which an adhesive force τ1 along a convex shape direction of the resin layer and a convex shape direction orthogonal to the resin layer are provided when the adherend is a glass plate The ratio R of the adhesive force τ2 is R = τ1/τ2 = 0.1 to 0.5.

The anisotropic adhesive sheet of the present invention exhibits different releasability depending on the peeling direction, and can have excellent adhesiveness in a specific direction and excellent peelability in a direction other than a specific direction. Thereby, it is possible to provide an anisotropic adhesive sheet which is firmly adhered to the adherend and which can be easily peeled off from the adherend when it is not required or bonded. Further, since the anisotropic adhesive sheet of the present invention is not restricted by the material type of the substrate and the adhesive, it can be used for various purposes.

1‧‧‧Substrate

2‧‧‧ resin layer

2a‧‧‧The lower part of the resin layer

2b‧‧‧ upper part of the resin layer

3‧‧‧Adhesive layer

4‧‧‧ Stripper layer

5‧‧‧ Support for peeling sheet

10‧‧‧ Anisotropic adhesive sheet

20‧‧‧ peeling film

Fig. 1 (a) and (b) are schematic cross-sectional views showing an example of an anisotropic adhesive sheet of the present invention, respectively.

2] (a) to (c) are schematic perspective views showing an example of a state before the anisotropic adhesive sheet layered adhesive layer of the present invention.

3] (a) and (b) are schematic cross-sectional views showing an example of a product using the 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 an anisotropic adhesive sheet of the present invention. In the anisotropic adhesive sheet 10, a resin layer 2 is formed on one surface of the substrate 1. An adhesive layer 3 is formed on the surface of the resin layer 2. The resin layer 2 has a concavo-convex structure on the surface on the side of the adhesive layer 3. 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 has an uneven structure only on the upper portion 2b of the resin layer 2. In the case of FIG. 1(b), the resin layer 2 is formed discontinuously on the surface of the substrate 1, and the adhesive layer 3 may contact the surface of the substrate 1 at a position where the resin layer 2 is not formed.

The base material 1 used in the anisotropic adhesive sheet 10 of the present invention is not particularly limited, and paper, a resin film, a resin sheet, a metal-containing sheet, an inorganic-containing sheet, or a laminated sheet thereof may be used. Any one. Examples of the paper substrate include high-quality paper, clay coated paper, art coated paper, resin coated paper, cellophane, and polyethylene laminated paper. Further, examples of the substrate of the resin film include a polyethylene film, a polypropylene film, a polyester film, a polyamide film, an acrylic film, a polycarbonate film, a polyimide film, a vinyl chloride film, and a dichlorochloride. A resin film such as a vinyl film or a polystyrene film. Examples of the substrate of the resin sheet include a polyolefin sheet and a vinyl chloride sheet. Polyester sheet, polyamide sheet, etc. Examples of the metal-containing sheet include a metal foil such as an aluminum foil, a copper foil or a stainless steel foil, a laminated sheet of a metal foil and a resin film, a metal vapor-deposited sheet such as an aluminum vapor-deposited sheet (which may be a vapor deposited film), or a resin containing metal particles. Film and so on. Examples of the inorganic-containing (compound) sheet include an inorganic vapor-deposited sheet such as an alumina vapor-deposited sheet or a cerium oxide-deposited sheet (which may be a vapor-deposited film).

The material and thickness of the substrate 1 are not particularly limited, and may be any material or thickness that suits the intended use. Therefore, in the present specification, the terms sheet and film are sometimes used without particular distinction in thickness, and one term may include the meaning of the other term.

In addition, in order to improve the applicability and adhesion of the resin layer 2, surface modification such as corona treatment or plasma treatment or anchor coating agent may be applied to the surface of the substrate 1 on the resin layer 2 side as needed. Easy bonding treatment such as coating.

A surface treatment can be performed on the surface of the substrate 1 opposite to the resin layer 2 depending on the application. For example, in the use of an adhesive tape, a release agent such as an organic hydrazine may be applied to form a release agent layer. Further, in the use of the window film, a coating layer such as a hard coating agent, an antifouling agent, an infrared (heat ray) release agent, or an ultraviolet ray release agent may be formed. In the use of labels, wallpapers, seals, decorative coats, stickers, and the like, various print layers, development layers, protective layers, and the like can be applied.

The resin layer 2 used in the anisotropic adhesive sheet 10 of the present invention is an important component for expressing anisotropic adhesion. Fig. 2 shows an example of a state before the anisotropic adhesive sheet layered adhesive layer of the present invention. In Fig. 2(a), the cross-sectional shape of the upper portion 2b of the resin layer 2 is formed into a substantially semicircular convex shape. In Fig. 2(b), the cross-sectional shape of the upper portion 2b of the resin layer 2 is formed into a substantially rectangular convex shape. In Fig. 2(c), the cross-sectional shape of the upper portion 2b of the resin layer 2 The shape is formed into a substantially triangular convex shape. As shown in FIG. 1(a), the lower portion 2a of the resin layer 2 shown in each of FIG. 2 is continuous on the surface of the substrate 1, but it may be as shown in FIG. 1(b), and the resin layer 2 is on the substrate 1. The surface is discontinuously formed.

The anisotropic adhesive sheet 10 of the present invention is characterized in that the resin layer 2 has a concave-convex structure on the surface of the adhesive layer 3 side, and the pattern of the uneven structure has anisotropy (concave structure in the longitudinal, transverse or squint directions) The pattern shape is different).

The adhesive force of the anisotropic adhesive sheet of the present invention is considered to be the total adhesive force of the adhesive to the adherend interface (1) and the stress (2) required for deforming the adhesive layer inside the adhesive layer. value. The present invention contemplates that anisotropic adhesion is exerted by causing a difference in stress (2) required for deformation of the adhesive layer in different peeling directions. By providing the uneven structure on the surface of the resin layer 2, the thickness of the adhesive layer 3 is changed, and when the anisotropic adhesive sheet 10 is peeled off, the volume of the adhesive layer which is deformed by the external force changes, and the adhesive force is in different peeling directions. There is a difference. Therefore, the resin storage elastic modulus used in the resin layer 2 needs to be larger than the storage elastic modulus of the adhesive used in the adhesive layer 3.

The resin used in the resin layer 2 is not particularly limited, and can be used as long as it can form and hold the uneven structure. Specific examples thereof include an acrylic resin, a polyester resin, an epoxy resin, an olefin resin, a polyether amine resin, a polyimide resin, a polyvinyl alcohol resin, a vinyl acetate resin, a nitrocellulose (nitrocellulose), and an alcohol. An acid resin, a phenol resin, a fluororesin, an organic resin or the like.

The method of forming the resin layer 2 on the substrate 1 may be a known method, and a method of applying a resin coating on the substrate 1 and a method of laminating the resin by melting the substrate 1 (crowding) Lamination method), use bonding A method of laminating a resin sheet and a substrate 1 in advance (dry lamination method) or the like.

The anisotropic adhesive sheet 10 of the present invention is characterized in that the resin layer 2 has a concave-convex structure on the surface of the adhesive layer 3 side, and the pattern of the uneven structure has anisotropy (concave structure in the longitudinal, transverse or squint directions) The pattern shape is different). As the pattern shape having an anisotropic concave-convex structure, it is most common to provide a stripe-like (longitudinal stripe or stripe-like) convex portion in the longitudinal direction or the width direction of the base material 1 composed of a long film. The pattern shape of (or recess). In addition, a pattern shape in which stripe-shaped convex portions (or concave portions) are provided in the oblique direction with respect to the flow direction of the base material 1 composed of a long film, and a cylindrical concave pattern in the longitudinal direction may be mentioned. A pattern shape or the like that is discontinuously arranged in the direction or the lateral direction.

As a method of forming a pattern having an anisotropic concavo-convex structure on the resin layer 2, a known method can be used. For example, it may be any one of the following methods: a method of extruding a molten resin on a substrate 1, pressing it with a patterned cooling roll, and transferring a pattern of the cooling roll; using a gravure processing method on the substrate 1 A method of applying a resin coating pattern on a pattern; a method of uniformly applying a thermoplastic resin or an ultraviolet curing resin to the substrate 1, and pressing a pattern of the mold to transfer a pattern shape on the surface of the resin.

The thickness of the resin layer 2 is not particularly limited, and an appropriate thickness can be selected in accordance with the shape of the pattern, the depth of the concave portion of the pattern portion, the physical properties of the coating material of the adhesive, and the like. The thickness of the resin layer 2 is usually about 3 to 50 μm. When the thickness of the resin layer 2 is less than 3 μm, it is difficult to exhibit the difference in the adhesive force due to the peeling direction. When the thickness of the resin layer 2 exceeds 50 μm, the resin layer 2 is disadvantageous in terms of cost, and the workability of the resin layer 2 is poor. This is not preferred.

Further, in order to increase the anchoring force of the adhesive layer, surface modification by corona treatment, plasma treatment, etc., and adhesion coating treatment such as anchor coating may be performed on the surface of the resin layer 2 in contact with the adhesive layer 3. .

The adhesive layer 3 used in the anisotropic adhesive sheet 10 of the present invention is adhered to the surface of the adherend, and is required to be firmly bonded during use, and can be easily used after use or when it is not required and the fitting is corrected. Stripping. In order to firmly bond in use, it is preferred that the surface of the adhesive layer 3 is smooth. Specifically, it is preferable that the surface of the adhesive layer 3 has an arithmetic mean surface roughness Ra of 5 μm or less. When the arithmetic mean surface roughness Ra exceeds 5 μm, the adhesion to the adherend may be deteriorated, or when the anisotropic adhesive sheet 10 is attached to the adherend, bubbles may be mixed.

The type of the adhesive is not particularly limited, and an adhesive such as an acrylic adhesive, a urethane adhesive, a rubber adhesive, or an organic enamel adhesive can be used. The thickness of the adhesive layer 3 is not particularly limited, and the thickness of the adhesive layer 3 is usually set to be about 5 to 100 μm. When the thickness of the adhesive layer 3 is less than 5 μm, it is difficult to fill the uneven structure of the resin layer 2, and when it exceeds 100 μm, there is no problem in performance, but there is a problem that the price becomes high.

The degree of anisotropic adhesion (the direction along the convex shape of the resin layer 2) according to the thickness of the resin layer 2, the thickness of the adhesive layer 3, and the pattern of the resin layer 2 (depth, width, space, and the like of the concave portion) The ratio R) of the adhesion force τ1 to the adhesion force τ2 orthogonal to the direction of the convex shape of the resin layer 2 changes. In order to express anisotropic adhesion, the design of the thickness of the resin layer 2, the thickness of the adhesive layer 3, and the pattern shape of the resin layer 2 is important. The surface of the adhesive layer 3 of the anisotropic adhesive sheet 10 is smooth, and therefore the adhesive in the thick portion of the resin layer 2 The thickness of the layer 3 is thinner than the portion where the resin layer 2 is absent or the portion of the resin layer 2 is thin. By mixing the thick portion and the thin portion of the adhesive layer 3, anisotropic adhesion is exhibited. The ratio K of the thickness T1 of the thinnest portion of the thickness of the adhesive layer 3 to the thickness T2 of the thickest portion is preferably K = T1/T2 = 0.2 to 0.8. When K is less than 0.2 and exceeds 0.8, it is difficult to exhibit anisotropic adhesion.

The adhesive may be a one-component adhesive containing only a main component, or a two-part adhesive in which a main component and a curing agent are mixed. An adhesion improver such as a decane coupling agent, an adhesion-imparting agent (tackifier) for improving adhesion properties, an antioxidant for improving durability, an ultraviolet absorber, and an antistatic effect imparting an antistatic effect may be added as needed. A catalyst, a catalyst for promoting a curing reaction, a coloring property for imparting an adhesive sheet, a light-blocking pigment, a filler, and the like.

Examples of the curing agent to be added to the pressure-sensitive adhesive layer 3 include an isocyanate compound, an epoxy compound, a melamine compound, and a metal chelate compound. Further, examples of the adhesion-imparting agent include rosin-based, coumarone-oxime-based, terpene-based, petroleum-based, and phenol-based.

As a method of forming the adhesive layer 3, a known method can be used. Specifically, the substrate 1 and the resin layer 2 can be laminated by a known application method such as reverse coating, comma coating, gravure coating, slit die coating, Meyer bar coating, or air knife coating. The adhesive is applied to the sheet, followed by drying and curing. Radiation such as ultraviolet rays can be irradiated depending on the type of the adhesive. Further, in order to promote the curing of the adhesive, aging (curing) can be performed at a predetermined temperature.

The anisotropic adhesive sheet of the present invention is characterized in that the adhesive force differs depending on the peeling direction. When the adherend is made into a glass plate, the adhesive force τ1 in the direction along the convex shape of the resin layer 2 and the convexity in the orthogonal to the resin layer 2 are preferable. The ratio R of the adhesion force τ2 in the direction of the shape is R = τ1/τ2 = 0.1 to 0.5. When R exceeds 0.5 (in other words, when τ2 is less than twice the value of τ1), it is difficult to achieve the adhesion to the adherend when the adhesive sheet is used, and the peeling property at the time of bonding correction when it is not required. Further, in consideration of the adhesion to the adherend when the adhesive sheet is used and the peelability at the time of bonding correction, it is desirable that R is small, but when R is less than 0.1, the degree of anisotropy is too large. The allowable angle of the peeling direction may become narrow.

Usually, in order to protect the adhesive layer 3, a release film, a release paper, or a release agent such as an organic hydrazine is applied to the surface of the substrate 1 opposite to the resin layer 2, and a roll is applied to the surface of the adhesive layer 3. Tape) winding. Fig. 3 is a schematic cross-sectional view showing a product example in which a product of a release film (release paper) and a roll (tape) winding shape are bonded. 3(a) shows an example in which the release sheet 20 is bonded to the anisotropic adhesive sheet 10, wherein the release sheet 20 is provided with a release agent layer 4 on one surface of the support 5, and the surface of the adhesive layer 3 is The stripper layer 4 is covered. 3(b) shows an example in which the release agent layer 4 is provided on the surface of the substrate 1 opposite to the resin layer 2, and when the roll is wound, the release agent layer 4 covers the surface of the adhesive layer 3. It should be noted that the terms adhesive sheet, adhesive tape, and adhesive film are sometimes distinguished according to the presence, thickness, width, and the like of the roll winding, but in the present specification, the term adhesive sheet and the anisotropic adhesive sheet are not particularly different. It is used in a broad sense and includes adhesive tape and adhesive film.

Since it is necessary to fill the concave portion of the uneven structure of the resin layer 2 with the adhesive layer 3, it is preferable to apply the adhesive directly on the sheet on which the substrate 1 and the resin layer 2 are laminated, depending on the uneven structure of the resin layer 2 and the viscosity of the adhesive. (degree of polymerization), after applying an adhesive on a release film or release paper, laminating the laminated substrate 1 And the surface of the resin layer 2 of the sheet of the resin layer 2. Further, in the case of a tape-shaped product, an adhesive may be applied to the substrate 1 side surface of the substrate 1 on which the surface of the substrate 1 is subjected to release treatment and the sheet of the resin layer 2, and tape winding may be performed. . The resin layer 2 having the cross section of the uneven structure and the adhesive layer 3 of the uneven structure of the buried resin layer 2 may be provided on both surfaces of the substrate 1.

[Examples]

Next, the present invention will be further described based on examples.

(Example 1)

Using a Meyer rod, a 50 μm-thick polyester film (ester A-1597 made from Toyobo Co., Ltd.) which is easily adhered on one side was applied, and an ultraviolet curing type hard coating agent was applied ( SEIKABEAM (registered trademark) PET HC-301, manufactured by Dairi Seiki Co., Ltd., was dried to a thickness of 8 μm, and dried in a hot air loop oven at 100 ° C for 1 minute to remove the solvent. After that, the coated surface of the hard coat coating agent was drawn by a comb (a hair comb having a thickness of 1 mm and a gap of 0.7 mm), and a stripe-like uniform groove (longitudinal stripe pattern) was formed in the application flow direction, and then used. The ultraviolet ray irradiator (using a metal halide lamp) was irradiated with ultraviolet rays under conditions of a cumulative light amount of 1500 mJ/cm ² to cure the hard coat coating agent. The adhesive is applied to the hard coating layer of the obtained grooved pattern, and the adhesive is applied to the 100 parts by weight of the acrylic adhesive (AS-409) manufactured by Tosoh Oil & Fats Co., Ltd., manufactured by Nippon Polyurethane Industry Co., Ltd. Isocyanate curing agent (Coronate (registered trademark) HL) 3 parts by weight), the thickness after drying (thickness from the surface of the polyester film to the surface of the adhesive layer) was 20 μm, and a hot air loop type oven of 100 ° C was used. It was dried for 2 minutes to remove the solvent from the adhesive. Thereafter, a separator (DiaFoil MRF-25 manufactured by Mitsubishi Plastics Co., Ltd.) was bonded to the surface of the adhesive layer to prepare an anisotropic adhesive sheet which was treated with an organic lanthanide on a PET film substrate having a thickness of 25 μm. A separator for the stripper. The obtained anisotropic adhesive sheet was kept warm for 5 days by a hot air loop type oven at 50 ° C, and aged to cure the adhesive to prepare an anisotropic adhesive sheet of Example 1.

(Example 2)

1 part by weight of an isocyanate-based curing agent (Coronate (registered trademark) HL) manufactured by Nippon Polyurethane Co., Ltd. was added to 100 parts by weight of an acrylic adhesive (AS-409) manufactured by Tosoh Oil & Fats Co., Ltd. as an adhesive. The anisotropic adhesive sheet of Example 2 was produced in the same manner as in Example 1 except that the thickness of the adhesive layer was changed to 16 μm.

(Example 3)

The stripe-like uniform groove (horizontal stripe pattern) was formed in a direction perpendicular to the application flow direction by a comb (hair comb) across the coated surface of the hard coating agent, and the same as in the first embodiment. The 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 changed to 12 μm.

(Comparative Example 1)

An adhesive sheet of Comparative Example 1 was produced in the same manner as in Example 1 except that the hard coat layer was not applied.

(Comparative Example 2)

By stripping the coated surface of the hard coating agent with a comb (hair comb), stripe-like shapes are formed in the flow direction of the application and the direction perpendicular to the application flow. An adhesive sheet of Comparative Example 2 was produced in the same manner as in Example 1 except that a uniform groove (lattice pattern) was used.

(Comparative Example 3)

An adhesive sheet of Comparative Example 3 was produced in the same manner as in Example 1 except that the thickness of the pressure-sensitive adhesive layer was changed to 9 μm.

Hereinafter, the method and result of the evaluation test are shown.

<Method for Measuring Adhesion of Anisotropic Adhesive Sheet and Adhesive Sheet>

A sample (width 25 mm, length 150 mm) in parallel (longitudinal) and vertical (horizontal) with respect to the flow direction of the application was taken from the anisotropic adhesive sheet or the adhesive sheet. The separator of the sample was peeled off and attached 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 at the time of peeling the sample in the direction of 180° at a peeling speed of 300 mm/min was measured using a tensile tester, and this was used as the adhesion of the sample. (N/25mm).

<Method for Measuring Surface Roughness (Arithmetic Mean Surface Roughness Ra) of Adhesive>

The separator of the sample was peeled off, and the surface roughness (arithmetic mean surface roughness Ra) of the surface of the adhesive layer was measured by a laser microscope (LEXT OLS4000 manufactured by Olympus Co., Ltd.) at a magnification of 5 times, and n=3. The measured average value is taken as the surface roughness of the sample.

The measurement results of the obtained anisotropic adhesive sheets of Examples 1 to 4 and Comparative Examples 1 to 3 were shown in Tables 1 and 2. The "pattern layer" of Table 1 and Table 2 means a resin layer formed of a hard coat coating agent.

In Comparative Examples 1 and 2, the anisotropy of the resin pattern was not obtained, so R was simply set as the adhesion (longitudinal)/adhesive force (horizontal).

The following contents are known from the measurement results shown in Tables 1 and 2.

The anisotropic adhesive sheets of Examples 1 to 4 in the present invention are based on the longitudinal direction. Different adhesion (peelability) is shown in the transverse peeling direction. On the other hand, Comparative Example 1 in which no resin layer was provided and the adhesive sheet of Comparative Example 2 in which lattice stripes were formed on the resin layer were not longitudinal. Any one of the effects of the transverse peeling direction is almost the same adhesive force (peelability). Further, the adhesive sheet of Comparative Example 3 in which the surface of the adhesive layer was not smooth (further, the ratio K of the thickness T1 of the thinnest portion of the thickness of the adhesive layer to the thickness T2 of the thickest portion was 0.1) was not affected by the longitudinal direction. Any one of the effects of the transverse peeling direction is almost the same adhesive force (peelability).

Industrial availability

The present invention provides an anisotropic adhesive sheet which can be firmly adhered to an adherend when used, and can be easily peeled off from the adherend when the adherend is not required and the fit is corrected.

The anisotropic adhesive sheet of the present invention is not limited by the material of the substrate or the adhesive, and has different peeling properties depending on the peeling direction. Therefore, it can be used, for example, for wallpaper, window film (film for window glass), marker sheet, label, decorative coat of arms, adhesive tape, recipient address label, delivery note for home delivery, protective film for optical film or display, Various uses such as protective sheets for metal plates or steel sheets.

1‧‧‧Substrate

2‧‧‧ resin layer

2a‧‧‧The lower part of the resin layer

2b‧‧‧ upper part of the resin layer

3‧‧‧Adhesive layer

10‧‧‧ Anisotropic adhesive sheet

Claims (3)

An anisotropic adhesive sheet, which is an adhesive sheet in which a resin layer having a cross section having a concavo-convex structure and an adhesive layer in which a concave-convex structure of the resin layer is buried is laminated on at least one surface of a substrate, wherein The pattern shape of the uneven structure of the resin layer has anisotropy, and the surface of the adhesive layer has smoothness, and the arithmetic mean surface roughness Ra is 5 μm or less. The anisotropic adhesive sheet according to claim 1, wherein the ratio K of the thickness T1 of the thinnest portion of the thickness of the adhesive layer to the thickness T2 of the thickest portion is K=T1/T2=0.2. ~0.8. The anisotropic adhesive sheet according to claim 1 or 2, wherein, when the adherend is a glass plate, the adhesive force τ1 in the direction of the convex shape of the resin layer is orthogonal to the The ratio R of the adhesive force τ2 in the direction of the convex shape of the resin layer is R = τ1/τ2 = 0.1 to 0.5.