JP2004115766A - Adhesive sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive sheet securing "easy air letting out" on pasting through unevenness on the surface of the adhesive layer, capable of pasting temporarily and performing strong actual adhesion afterwards. <P>SOLUTION: This adhesive sheet 10 installed with many projecting bodies 2a on the surface of an adhesive layer 2 on a substrate sheet 1 is provided by presenting many projecting bodies having different heights h as mixed. By the surface unevenness of the adhesive layer caused by the projecting bodies, the easy air letting out is secured and also by pushing it with a light pressure, the adhesive layer makes a contact with a material to be adhered mainly with the top parts of the projecting bodies for setting the position by a temporary adhesion. By further pushing forcefully, the projecting bodies having lower height can make a contact with the substrate to obtain more contacting parts to get a sufficiently strong actual adhesion. Further, on the surface of the adhesive layer, it is better to laminate a releasing sheet 3 having a releasing surface having a reverse unevenness shape to the unevenness shape of the adhesive layer. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer surface with irregularities. In particular, the present invention relates to a pressure-sensitive adhesive sheet having "easiness of air bleeding" in which air is not easily entrapped at the time of sticking to an adherend, and capable of temporary sticking and strong permanent bonding.
[0002]
[Prior art]
Generally, the surface of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is flat, and therefore, when the pressure-sensitive adhesive sheet is stuck to an adherend, it is easy to embrace air unless it is stuck carefully. In such a case, if a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer surface having an uneven surface is used, an air escape path is formed between the protrusions on the surface of the pressure-sensitive adhesive layer, so that the entrapment of air is improved. Examples of the pressure-sensitive adhesive sheet having such a property that the surface of the pressure-sensitive adhesive layer has irregularities and is hard to entrap air (this is referred to as “easiness of air release” in this specification) include, for example, The pressure-sensitive adhesive sheets disclosed in Patent Literature 1, Patent Literature 2, and the like are mentioned. For example, in the pressure-sensitive adhesive sheet disclosed in Patent Document 2, as in the pressure-sensitive adhesive sheet 30 illustrated in the perspective view of FIG. It discloses a shape in which convex bodies 32a each having a height of 0.3 mm and a height (difference in height) from the surface of 20 μm are arranged vertically and horizontally at an interval of 1 mm.
[0003]
[Patent Document 1]
Japanese Patent No. 2994411 [Patent Document 2]
Japanese Utility Model Registration No. 2503717
[Problems to be solved by the invention]
However, as shown in FIG. 2, when the heights of all the projections 32a are the same, only a portion near the top of the projections is pressed with light pressure so as to contact the adherend, and is temporarily bonded and positioned. After that, even if the adhesive layer is strongly pressed and finally bonded, a portion of the adhesive layer in contact with the adherend is not sufficiently obtained, and a sufficiently strong adhesive force may not be obtained.
[0005]
That is, an object of the present invention is to secure “easiness of air release” at the time of sticking by the unevenness of the surface of the pressure-sensitive adhesive layer, to perform temporary sticking, and thereafter, to make it possible to perform strong final bonding. is there.
[0006]
[Means for Solving the Problems]
Therefore, in order to solve the above problems, in the pressure-sensitive adhesive sheet of the present invention, in a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer provided on a base sheet, the pressure-sensitive adhesive layer has a large number of convex bodies protruding outward from the surface thereof. And a large number of convex bodies having different heights are mixed.
[0007]
By adopting such a configuration, easiness of air bleeding is secured by the unevenness of the surface of the pressure-sensitive adhesive layer formed by the convex body, and the top of the high convex body when pressed with light pressure. Can be positioned by temporary bonding by mainly contacting the adherend, and if pressed more strongly, the low-height convex body also contacts the adherend, including the low-height convex body. Since a sufficient contact portion with the attached body can be obtained, sufficiently strong final bonding can be performed.
[0008]
Further, the pressure-sensitive adhesive sheet of the present invention, in the above-described configuration, further has a configuration in which a release sheet having a release surface having a concave-convex shape reverse to the concave-convex shape of the surface is laminated on the surface of the pressure-sensitive adhesive layer. .
With such a configuration, it is easy to form a convex body on the pressure-sensitive adhesive layer, and further, at the time of storage of the pressure-sensitive adhesive sheet, at the time of distribution, at the time of use, and the like, the surface unevenness due to the convex body. The shape can be easily maintained.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0010]
(Unevenness of the pressure-sensitive adhesive layer surface due to the convex body)
The pressure-sensitive adhesive sheet 10 of the present invention has a pressure-sensitive adhesive layer 2 provided on a base sheet 1 as schematically shown in a cross-sectional view of FIG. The surface has an uneven shape due to a large number of convex bodies 2a projecting outward (upward in the drawing). Moreover, the convex body 2a has a configuration in which many convex bodies having different heights h are mixed. In addition, more preferably, as illustrated in FIG. 1, on the surface of the pressure-sensitive adhesive layer 2, a release sheet 3 having a release surface having a concave-convex shape reverse to the concave-convex shape of the pressure-sensitive adhesive layer surface is laminated. I do.
[0011]
The height h of the convex body 2a referred to in the present invention is defined as the top of the convex body based on the lower boundary of the adhesive layer 2 (the boundary between the base sheet 1 and the adhesive layer 2 in the drawing). Part height. That is, it is the thickness of the portion of the pressure-sensitive adhesive layer at the top of the convex body. The height of the convex body in the present invention is not the height (difference in height) of the top of the convex body with reference to the bottom of the valley 2b between the adjacent convex bodies. The reason is that the height of the valley bottom of the valley 2b between adjacent convex bodies (the height difference based on the lower boundary of the adhesive layer 2) does not need to be constant in the present invention as illustrated in the drawings. It is. This is because, for example, between convex bodies having different heights based on valley bottoms having different heights, the height h of the convex bodies defined by the present invention may be the same. The lower boundary (the boundary with the base material sheet) of the pressure-sensitive adhesive layer 2 is a plane. However, as a special case, if the surface is not a plane but an uneven surface, an arbitrary horizontal portion (an uneven surface of the boundary surface) may be used. The average height or the like may be used as a reference plane and the height difference from this reference plane may be used as the height h of the convex body.
[0012]
As described above, by mixing a large number of convex bodies having different heights, when pressed with a light pressure, the many convex bodies having a relatively high height are deformed so as to be slightly crushed by the pressure. Since the periphery of the top is mainly in contact with the adherend, even when the attachment position needs to be corrected, it can be easily peeled off with a light force and can be temporarily attached by temporary adhesion. Then, if it is temporarily attached at a correct position, it is pressed with strong pressure. Then, the relatively high convex body, which is already in contact with the top, is deformed so as to be further crushed, while the contact portion with the adherend spreads to its hillside, and A large number of relatively low convex bodies that were not in contact with the body also deformed so as to be crushed by pressure in contact with the adherend, around the top, and furthermore, on the hillside, or Furthermore, since even the valley bottoms of some of the valleys come into contact with the adherend, strong permanent bonding can be achieved.
[0013]
However, if the heights of all the convex bodies are the same, the temporary bonding is performed by contact with the adherend in which the vicinity of the tops of all the convex bodies is involved, and thereafter, strong bonding is performed for the final bonding. In the bonding when pressure is applied, in all the convex bodies that are already in contact with the top, the contact portions are spread on the hillsides. At this time, as the pressure increases, the contact portion with the adherend increases, but since the convex portion deforms and the hillside portion can be contacted only after the deformation, the degree of increase of the contact portion with respect to the pressure increase is small. . This is the reason why it is difficult to obtain a strong adhesive force even when pressed with a strong pressure when the heights of all the convex bodies are the same.
[0014]
In addition, if the slope of the hillside of the convex body is made gentle, the degree of the increase of the contact portion with respect to the pressure increase can be increased, and in this point, the contact area with the adherend is reduced with less deformation of the convex body. Can be increased. However, if such a smooth convex body, the undulation of the surface unevenness of the pressure-sensitive adhesive layer becomes too large, and becomes easy to see as a surface unevenness pattern after pasting to the adherend. There is a limit. However, if a large number of convex bodies having different heights are mixed as the convex bodies, even if such a surface irregularity pattern does not occur or occurs, it is inconspicuous, and temporary bonding and strong permanent bonding can be performed. It is.
[0015]
The height h of the convex body 2a preferably has at least two levels, more preferably three or more levels. This is because, with the increase in the pressing pressure, the contact portion with the adherend can be more smoothly increased. Then, many convex bodies having these different height levels are mixed. If the mixture is not conspicuous in the end, the convexes having different heights can be combined with each other (at least the convexes having the same height so that not all of the adjacent convexes have the same height h). It may be arranged regularly (with respect to the shape), but in order to make it less noticeable, it is better to mix the protrusions at the same height randomly so as not to concentrate.
[0016]
In addition, the shape of the convex body is not particularly limited. For example, the shape of the convex body (the vertical cross-sectional shape), the top, the side surface, the valley, and the like are arbitrary such as a curve, a straight line, and a combination thereof. However, since the valleys need to be formed as air bleeding layers at least at the time of sticking, and a way to allow air to escape is used, it is useless if they are scattered sporadically. For this reason, it is preferable that the valleys are continuous in a horizontal plane so that an air escape path is formed, that is, they form a “groove”. As for the continuity of the valleys, it is preferable that the valleys are continuous at least for a distance (at least 5 mm or more, more preferably 10 mm or more) at which air can escape at the time of sticking. From the viewpoint of avoiding jamming, it is more preferable that the pressure-sensitive adhesive sheet be continuous from end to end over the entire horizontal plane.
[0017]
Next, the horizontal cross-sectional shape of the convex body 2a in the horizontal plane is, for example, a polygon including a regular polygon such as a triangle, a quadrangle, a pentagon, and a hexagon, a circle, an ellipse, or an infinite length or a finite length with a finite width. And the vertical cross-sectional shape (in a vertical plane) is a trapezoid, a semicircle, a semi-ellipse, a triangle, or the like. The horizontal cross-sectional shape of each convex body in the horizontal plane may be irregular.
The arrangement of the convex bodies in the horizontal plane may be regularly arranged in a lattice or the like, or may be irregularly arranged.
On the other hand, the shape of the valley becomes a shape corresponding to the shape of the convex body and its arrangement.
[0018]
By the way, the specific size of each convex body 2a depends on the application, but the height difference from the valley bottom is usually 3 to 100 μm, more preferably 10 to 100 μm. If the height difference is less than 10 μm, particularly less than 3 μm, it is not possible to secure sufficient air bleeding easily. Conversely, if it is more than 100 μm, even if a deep valley is provided, the pressure-sensitive adhesive layer surface Irregularities remain even after sticking, and it is easy to impair the beauty.
[0019]
As illustrated in the cross-sectional view of FIG. 1, the convex portions 2 a of the pressure-sensitive adhesive layer 2 have a valley portion 2 b between adjacent convex portions 2 a, and the valley portion 2 b also has a valley bottom portion on the base sheet 1 side. Although not shown, other than the configuration forming the pressure-sensitive adhesive layer 2, a configuration in which the pressure-sensitive adhesive layer 2 is not provided on the base sheet 1 side of the valley bottom may be employed. However, in the case of the latter, if so in many valleys, since the adjacent convex bodies are not connected by a continuous adhesive layer, after sticking, the adhesive sheet becomes unnecessary, and when peeling the adhesive sheet, In some cases, a problem arises in that a part of the pressure-sensitive adhesive layer (convex body) falls off the pressure-sensitive adhesive sheet, remains on the adherend side, and is difficult to peel cleanly. In this respect, the former as shown in FIG. 1 is more preferable.
[0020]
In the case where adjacent convex bodies 2a are connected by a continuous pressure-sensitive adhesive layer 2 as shown in FIG. 1, only the convex bodies 2a of the pressure-sensitive adhesive layer 2 are formed separately from other pressure-sensitive adhesive layer parts. However, it is preferable to form all the pressure-sensitive adhesive layers 2 including the convex body 2a as an integrated continuous layer with the same pressure-sensitive adhesive, without distinction, from the viewpoint of easy production. For this purpose, as described below, a release sheet having a concave and convex shape reverse to the desired surface irregularity of the pressure-sensitive adhesive layer is prepared, and a pressure-sensitive adhesive is applied thereto to form a pressure-sensitive adhesive layer. May be laminated.
[0021]
In addition, the thickness of the pressure-sensitive adhesive layer (the whole) (which becomes the height h of the convex body) may be determined according to the use, and is about 10 μm to 200 μm. If the thickness is less than 10 μm, the adhesive strength (adhesive strength) becomes insufficient, and if it exceeds 200 μm, the cost increases.
[0022]
(Material of adhesive layer and formation method)
The pressure-sensitive adhesive layer 2 has a surface unevenness as described above on its surface, and as a pressure-sensitive adhesive used for forming such a pressure-sensitive adhesive layer, a conventionally known pressure-sensitive adhesive may be appropriately used depending on the application. good. For example, an adhesive such as a rubber-based adhesive, an acrylic-based adhesive, or a silicone-based adhesive is used.
[0023]
Further, the method of forming the pressure-sensitive adhesive layer having the above-mentioned desired unevenness on the surface is not particularly limited, but a release sheet having a release surface having an uneven shape reverse to the unevenness is prepared. Forming the pressure-sensitive adhesive layer on the release sheet by a known coating method such as roll coating is one preferable method in that the uneven shape can be easily formed. The base sheet is formed by forming a pressure-sensitive adhesive layer on a release sheet to form a laminated sheet, and then attaching and laminating the base sheet to the pressure-sensitive adhesive layer surface of the laminated sheet, whereby a desired pressure-sensitive adhesive sheet is formed. can get.
[0024]
[Release sheet]
Next, as the release sheet 3, a release sheet having a flat release surface can be used (after forming a desired uneven shape on the surface of the adhesive layer, the release sheet is laminated. In some cases, air exists between the valley of the pressure-sensitive adhesive layer and the release sheet). However, as the release sheet, it is preferable to use a release sheet having a concave / convex shape corresponding to the concave / convex shape on the surface of the pressure-sensitive adhesive layer (reverse to the concave / convex shape) on the release surface. As a result, as described above, by forming the pressure-sensitive adhesive layer on the release sheet by a coating method or the like, it is possible to easily form a surface uneven shape by a desired convex body on the surface of the pressure-sensitive adhesive layer. Further, the entire pressure-sensitive adhesive layer including the convex portion can be formed as an integrated continuous layer. In addition, when the pressure-sensitive adhesive sheet is stored, distributed, used, or the like, the surface irregularities of the pressure-sensitive adhesive layer due to the convex body are not crushed, and the shape can be easily maintained.
[0025]
Such a release sheet having a desired uneven shape on the release surface can be obtained by applying a conventionally known shaping means such as embossing to a conventionally known release sheet.
[0026]
For example, as a material of the release sheet, for example, a resin sheet such as polyethylene terephthalate or a sheet such as paper, a silicone resin, a melamine resin, a polyolefin resin, or a resin obtained by adding a release agent such as a wax, or the like. It is a laminate of layers, or a resin sheet or the like which itself has releasability, such as a polyolefin-based resin.
The thickness of the release sheet may be determined according to the intended use, and is, for example, about 20 to 300 μm.
[0027]
In order to make the release surface of the release sheet a desired uneven shape, conventionally known embossing may be applied, but as the embossing, for example, an embossing roller is pressed as an embossing plate on a heated sheet. A typical example is a method of shaping by shaping. In addition, when forming a resin layer on a resin sheet or paper by a melt coating method, a film forming simultaneous shaping method using an embossing roller having the surface of a cooling roller as an embossing surface may be used. Alternatively, instead of the melt coating method, a method may be used in which an ionizing radiation-curable resin that is cured by ultraviolet rays or electron beams is used, and the resin layer is formed as a cured product at the same time as the application and curing. Also, a desired uneven shape may be formed on the release surface by stencil printing using a known printing method such as screen printing.
In addition, as a method of forming a desired uneven shape on the embossing plate, a known forming method such as a multi-step etching method using a carbon tissue or the like (see Japanese Patent Application Laid-Open No. H8-1770), a mechanical cutting method, a laser processing method, or the like. Good according to.
[0028]
(Base sheet)
As the base sheet 1, a conventionally known base sheet may be appropriately used depending on the application. For example, a sheet made of a resin sheet, a metal foil, or a fibrous sheet such as paper, nonwoven fabric, woven fabric, veneer, or a composite sheet such as a laminated sheet of two or more of these or a resin-impregnated nonwoven fabric. is there. Note that a transparent (uncolored, colored), opaque, translucent, or other sheet is used as the resin sheet. The thickness of the base sheet may be determined according to the intended use, and is, for example, about 5 to 500 μm, usually about 20 to 300 μm.
[0029]
[Others]
The pressure-sensitive adhesive sheet may have a configuration in which visible or invisible information such as a pattern, a pattern, an unevenness, or the like, a print, a code, a symbol, an image, or the like is applied to the adhesive sheet by a known printing / coating means or the like as needed. . Usually, these are applied to one side (front or back) or both sides of the substrate sheet. Those on which a pattern such as a picture is given can be used as a decorative sheet in building material applications. It should be noted that there is also a solid pattern on the entire surface such as coloring on the entire surface as the pattern. The invisible information is, for example, information such as patterns and characters that can be read by irradiation of ultraviolet rays or infrared rays by printing fluorescent ink or infrared absorbing ink.
[0030]
Further, the pressure-sensitive adhesive sheet may have a configuration in which various functions are imparted as necessary. The functional properties include, for example, abrasion resistance, scratch resistance, stain resistance, antifogging property, antireflection property, antistatic property, heat insulation property, antibacterial property, electromagnetic wave shielding property, and the like. Depending on their functions, these may be added to a base material sheet such as a resin sheet or the like, or may be formed on the base material sheet with a layer such as the substance or an ink or coating liquid containing the substance. And so on. For example, abrasion resistance, abrasion resistance, and the like are determined by adding a lubricant such as silica to a resin sheet or by applying a coating solution containing the lubricant on the surface of a base sheet.
[0031]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.
[0032]
[Example 1]
An adhesive sheet 10 as shown in FIG. 1 was produced as follows.
First, as a release sheet, a surface of a 150 μm-thick polypropylene-based resin sheet as a release surface, using an embossing roller, to form irregularities of a desired pressure-sensitive adhesive layer surface irregularities and reverse irregularities, A release sheet 3 was obtained.
[0033]
Next, an acrylic pressure-sensitive adhesive is applied to the release surface of the release sheet 3 where the unevenness is formed, so that the concave portion of the release surface is completely filled and the pressure-sensitive adhesive layer is further covered thereon. The adhesive layer 2 was formed by heating and drying to obtain a laminated sheet in which a release sheet and an adhesive layer were laminated.
[0034]
Then, a 50 μm-thick polyethylene terephthalate sheet as a base sheet 1 is attached to the surface of the pressure-sensitive adhesive layer 2 of the laminated sheet using a laminator, and the surface of the pressure-sensitive adhesive layer 2 as shown in the sectional view of FIG. A desired pressure-sensitive adhesive sheet 10 having many convex bodies 2a having different sizes was obtained.
[0035]
The pressure-sensitive adhesive layer 2 of this pressure-sensitive adhesive sheet has a plurality of horizontal cross-sectional shapes having a height h of 35 μm and 50 μm (a difference in height from a valley valley of 15 μm and 30 μm, respectively) having a height of 2 mm at the bottom. The protruding body 2a having rounded corners similar to a truncated pyramid does not expose the base material sheet at the valley bottom between adjacent protruding bodies, and all the protruding bodies have surface irregularities continuous with the adhesive layer. Was something.
[0036]
[Comparative Example 1]
In Example 1, the height h of all the convex bodies was made the same (h = 45 μm, the height difference from the valley bottom 25 μm) by changing the uneven shape of the release surface of the release sheet at the time of embossing. Other than that produced the adhesive sheet similarly to Example 1.
[0037]
(Performance evaluation)
Each of the pressure-sensitive adhesive sheets of the above Examples and Comparative Examples was temporarily bonded to a transparent glass plate lightly with a rubber squeegee while bleeding air, and then strongly pressed to perform final bonding. As a result, there was no air residue in both the examples and comparative examples, and the ease of air release was good. However, in Comparative Example 1, strong adhesion could not be obtained by the actual bonding. On the other hand, in Example 1, strong adhesion was obtained by the final bonding, and the surface (irregularity) state was also good.
[0038]
【The invention's effect】
(1) According to the pressure-sensitive adhesive sheet of the present invention, ease of air release is ensured, and positioning by temporary bonding can be performed with light pressure, and sufficiently strong main bonding can be performed with stronger pressure.
(2) Further, if a release sheet having a release surface having a concave-convex shape reverse to the concave-convex shape of the surface is laminated on the surface of the pressure-sensitive adhesive layer, the convex body to the pressure-sensitive adhesive layer is formed. In addition to being easy to form, it is easy to maintain the shape of the surface irregularities due to the convex body when storing, distributing, and using the pressure-sensitive adhesive sheet.
[Brief description of the drawings]
FIG. 1 is a sectional view conceptually illustrating a pressure-sensitive adhesive sheet according to the present invention.
FIG. 2 is a perspective view showing an example of a conventional pressure-sensitive adhesive sheet.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Base sheet 2 Adhesive layer 2a Convex body 2b Valley 3 Release sheet 10 Adhesive sheet 30 Adhesive sheet 31 Base sheet 32 Adhesive layer 32a Convex body h Height of convex body

Claims (2)

In a pressure-sensitive adhesive sheet provided with a pressure-sensitive adhesive layer on a substrate sheet,
The pressure-sensitive adhesive sheet, wherein the pressure-sensitive adhesive layer has a large number of convexes protruding outward from the surface thereof, and a large number of convexes having different heights are mixed. The pressure-sensitive adhesive sheet according to claim 1, wherein a release sheet having a release surface having a concave-convex shape reverse to the concave-convex shape of the surface is laminated on the surface of the pressure-sensitive adhesive layer.

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