JP2002241719A - Adhesive sheet and adhesive structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare an adhesive sheet which can effectively prevent the swelling of the sheet due to a gas evolved out from an adherend, even when used outside for a relative long period in a state adhered to the adherend containing an easily moisture-absorbing substance, and additionally even when a substrate having a relatively low steam-penetrating property is used to form the adhesive sheet. SOLUTION: This adhesive sheet which comprises a substrate and an adhesive layer disposed and fixed to the back side of the substrate and is adhered to a side to be adhered of the adherend, is characterized in that the mutual distance of arranged grooves is 10 to 520 μm and that channels exist even after adhered to the adherend and then heated at 85 deg.C for 30 min. In the adhesive sheet, the adhesive layer has a plurality of the grooves arranged in approximate parallel to each other at a prescribed distance on the adhesive side to be adhered to the surface to be adhered, and the channels communicating with the outside and demarcated with the grooves and the surface to be adhered in a state adhered to the surface to be adhered are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive sheet comprising a base material and an adhesive layer fixedly arranged on the back surface of the base material, the adhesive sheet being bonded to an adherend surface of an adherend, The adhesive layer relates to an improvement in an adhesive sheet that forms a channel communicating with the outside between the adhesive layer and the adhered surface while being adhered to the adhered surface. According to the present invention, even when a substrate including a fluororesin or a metal layer and having a relatively low water vapor permeability is used and adhered to an adherend including a material (e.g., polycarbonate) which easily generates outgas, Swelling (a phenomenon in which gas stagnates between the adhesive sheet adhered to the adherend and the adherend and the swelling is visually recognized from the substrate surface of the adhesive sheet) can be effectively prevented, An adhesive sheet can be provided.

[0002]

2. Description of the Related Art Heretofore, in an adhesive sheet including a base material and an adhesive layer containing an adhesive fixedly arranged on the back surface of the base material, an adhesive (adhesive surface) is applied to the surface (adhesive surface) of the adhesive layer. Those having a convex portion formed of are widely known. By forming such a convex portion, it is possible to control the actual (true) bonding area to a relatively small range and to enhance the removability. In addition, the projections as described above are arranged on the bonding surface such that a channel communicating with the outside is formed between the bonding layer and the bonding surface in a state where the bonding sheet is bonded to the bonding surface. preferable. According to this configuration, when air is stuck (entangled) between the adhesive sheet and the adherend surface of the adherend to which the adhesive sheet is stuck, the air is generated in the portion where the air is stuck.
So-called "bubbles" can be easily removed. That is, the air bubbles caught between the adhesive sheet and the adherend surface are:
By the crimping operation of the adhesive sheet, the adhesive sheet can be easily released to the outside through the channel.

[0003] For the adhesive sheet as described above, for example, Japanese Utility Model Registration No. 2503717, Japanese Utility Model Registration No. 2587198, International Patent Publication WO93 / 051.
No. 23, JP-A-11-209704 and the like. Here, an example of a method of forming a concave-convex adhesive surface having the above-described convex portion on the adhesive surface will be described.

First, a liner having a release surface having a predetermined uneven structure is prepared. A coating containing an adhesive polymer (adhesive coating for forming an adhesive layer) is applied to the release surface of the liner and dried to form an adhesive layer. As a result, the uneven structure (negative structure) of the liner is transferred to the surface of the adhesive layer that comes into contact with the liner (this is the adhesive surface of the adhesive sheet), and the uneven surface has a predetermined structure (positive structure) on the adhesive surface. Form a surface. The unevenness of the bonding surface is formed between (a) a plurality of convex portions that come into contact with the adherend and (b) between convex portions adjacent to each other, and communicates with the outside when the adherend comes into contact with the convex portions. And is designed in advance to include a groove. In the adhesive layer having the uneven adhesive surface of the adhesive sheet as described above, it has been proposed that the thickness, the depth of the groove, and the arrangement interval of the groove are appropriately determined within a range that does not impair the effects such as the bubble removal property. I have. For example, the thickness of the adhesive layer is usually 0.01 to
The range is 0.2 mm. The depth of the groove is usually 5
The range is 200 μm. The groove spacing is usually 0.1
１１11 mm.

On the other hand, when a normal adhesive sheet (one having a flat adhesive surface) is attached to a certain kind of plastic (polycarbonate or the like), some gas (water vapor or the like) is generated from the plastic and “ Swelling due to outgassing "
Sometimes occurred. If an adhesive sheet having the above-mentioned uneven adhesive surface is used, the above registered utility model 25037 can be obtained.
As disclosed in Japanese Patent Application Publication No. 17 and Registered Utility Model No. 2587198, it was possible in some cases to prevent sheet swelling due to outgassing.

[0006]

However, it has been found that when the sheet swells due to the outgas as described above, the swelling cannot be prevented unless the following points are taken into consideration. When the base material of the adhesive sheet has a high permeability to outgas such as water vapor generated from the adherend, it is used continuously in a relatively high temperature environment, such as being used outdoors for a relatively long time, and the amount of generated gas is small. At most, most of the gas escapes through the channels of the adhesive layer, and any gas that escapes through the channels can escape through the substrate. On the other hand, when the gas permeability is low, such as when the base material of the adhesive sheet includes a metal deposition layer, and when the amount of generated gas is large, the gas that has escaped through the channel cannot pass through the base material, and the adhesive sheet It has been found that swelling occurs between the substrate and the adherend.

In such a case, the above registered utility model 2503
In Japanese Patent Publication No. 717 and Japanese Utility Model Registration No. 2587198, a channel having a relatively large volume, as specifically disclosed as an example, was advantageous for enhancing the gas venting efficiency. However, on the other hand, it has been found that the true adhesion area with the adherend is reduced, the effect of maintaining the adhesion is reduced, and in fact, the adhesive sheet is peeled off and swelling due to outgas is generated. . In addition, in order to prevent swelling even when used continuously in such a relatively high temperature environment, the bonding surface should be set so that swelling due to outgas does not occur even in an accelerated environmental test at a high temperature such as 85 ° C. It was also found that it was important to design the uneven structure.

[0008] Accordingly, an object of the present invention is to provide a device that is adhered to an adherend containing a substance that easily absorbs moisture, such as polycarbonate, for a long period of time outdoors (ie, continuously in a relatively high temperature environment). Even when used, and even when an adhesive sheet is formed using a relatively low water vapor permeable substrate in addition to them, it is possible to effectively prevent the sheet from swelling due to outgas from the adherend, An object of the present invention is to provide an adhesive sheet.

[0009]

In order to solve the above-mentioned problems, the present invention comprises a base material and an adhesive layer fixedly arranged on the back surface of the base material. The adhesive layer, wherein the adhesive layer is spaced apart from the adhesive surface adhered to the adherend surface by a predetermined distance, the groove and the adherend surface are defined. In the adhesive sheet that forms a channel that communicates with the outside, in the adhesive sheet, the arrangement interval of the grooves is 10 to 520 μm, and the channel adheres the adhesive sheet to the adherend and is heated at 85 ° C. for 30 minutes. An adhesive sheet characterized by being present is provided.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION (Structure of Adhesive Layer) The adhesive layer of the adhesive sheet of the present invention, in a state of being adhered to a surface to be adhered, communicates with the outside defined by the groove of the adhesive layer and the surface to be adhered. A channel having a structure in which: (1) the arrangement interval of the grooves arranged substantially in parallel to each other is 10 to 520 μm; and (2) the channel adheres the adhesive sheet to the adherend and reaches 85 ° C. For 30 minutes, and the channel is in communication with the outside. The groove is defined by a plurality of protrusions made of an adhesive. That is, the adhesive layer has a convex portion made of an adhesive surrounded by the groove.

In the adhesive layer, the arrangement interval of the grooves is 10
If it is less than μm, the area of the bonding area per channel (true bonding area) is too small, and if used outdoors for a relatively long time (ie, continuously in a relatively high temperature environment), the bonding is The holding effect is reduced, the adhesive sheet is peeled off, and swelling due to outgas occurs. On the other hand, if the arrangement interval of the grooves exceeds 520 μm, the number of channels per unit true adhesion area becomes too small, which is disadvantageous for enhancing the gas venting efficiency of the channels. From such a viewpoint, the arrangement interval of the grooves is preferably 50 to 515 μm, particularly preferably 100 to 510 μm.
It is. The arrangement interval of the grooves is a distance between adjacent grooves measured along a direction parallel to the bonding surface. In a cross section of the groove in a direction perpendicular to the bonding surface, the groove has a width of a predetermined dimension along the measurement direction. The arrangement interval of the grooves is the distance between the width direction center of the groove and the width direction center of the adjacent groove.

Generally, the groove of the adhesive layer includes a set of a plurality of grooves arranged substantially in parallel and substantially in parallel to one direction (first direction) included in a plane parallel to the bonding surface. ing. Another direction (second direction) included in the plane horizontal to the bonding surface
Direction) and may be provided with another set of grooves that are substantially regularly arranged substantially parallel to each other and intersect with the grooves parallel to the first direction. In such a case, for example, two sets of grooves are orthogonal to each other, formed on the bonding surface along a line that draws a checkerboard-shaped geometric pattern, and at the outer peripheral end of the bonding sheet bonded to the adherend, The opening can be formed such that at least one, preferably a plurality of grooves communicate with the outside. Like this 2
When a set of grooves is provided, the arrangement interval of the grooves is an average value of the arrangement intervals measured in each of the two sets. In the case where another set including a plurality of grooves arranged along directions different from the above two directions is further present, similarly, the average value of the arrangement intervals measured in all the sets is used as the value of the groove. Defined as placement intervals.

The shape of the groove viewed from the direction perpendicular to the bonding surface in plan view is usually a straight line (strip or belt) having a constant width (the short axis dimension in the direction horizontal to the bonding surface). For example, when including two sets of grooves orthogonal to each other as described above,
Such straight lines form a grid. Further, as a specific example in which three or more sets of grooves are included, for example, two sets of one set of rectangles which are orthogonal to each other and are formed along a line that draws a checkerboard pattern on the bonding surface, and constitute the checkerboard Third or third and fourth sets of grooves are arranged along one or both diagonals. Also, each set may be composed of grooves parallel to each other, and three sets of grooves intersecting each other at an angle of 60 degrees may be combined. In these cases, the plan view shape of the convex portion surrounded by the groove is a triangle. As long as the effects of the present invention are not impaired, the width of the groove may fluctuate along the extending direction of the groove. For example, it may be widened or narrowed at predetermined intervals along the extending direction of the groove.

The volume of the channel is determined by a value In measured at the initial stage when the adhesive sheet is adhered to the adherend and a value Ah measured after the adhesive sheet is adhered to the adherend and heated at 85 ° C. for 30 minutes. Are preferably in the range of 1 × 10 ⁵ to 2 × 10 ⁷ μm ³ as measured values per 1 mm ^{2 of the} apparent adhesion area. Of course, the initial value (In) is within the above-mentioned effective range, and the channel does not excessively shrink even after heating at 85 ° C. for 30 minutes.
However, if the above range is effective, it is possible to effectively prevent the sheet from swelling due to outgassing.

Either the initial value In or the value after heating Ah
One has an apparent adhesion area of 1 mm²1 per measured value
× 10⁵μm³Less than the channel volume
Too high to effectively increase the degassing efficiency of the channel,
This effectively prevents the seat from bulging due to outgassing.
May not work. Conversely, either In or Ah
One side has an apparent adhesion area of 1 mm²Per measurement
2 × 10⁷μm³Is exceeded, the true bonding area becomes smaller.
Too much, the adhesive sheet peels off, and swells due to outgas.
This may occur. From this point of view,
Both In and Ah have an apparent adhesion area of 1 mm²Hit
And more preferably 2 × 10 ⁵~ 1 × 10⁷
μm³Particularly preferably 5 × 10⁵~ 5 × 10⁶μm³of
Range.

In this specification, the term "apparent adhesive area" refers to the area of the surface covered with the adhesive sheet. That is, a “(true) bonding area” in which the top surface of the convex portion of the bonding layer is bonded to the adherend surface, and a “non-bonding area” corresponding to the groove of the bonding layer and not actually bonded. Are regarded as “apparent adhesion area”.

After the adhesive sheet is adhered to the adherend, the channel volume can be calculated arithmetically by measuring the dimensions of the groove in the adhesive layer and the true adhesive area, and using the measured values. The dimensions of such grooves and the true bonding area are, for example,
The measurement can be performed by using a combination of a microscope and an image processing device. For a preferable example of such a measuring method, refer to examples described later.

The other dimensions of the adhesive layer are appropriately determined so that the dimensions (volume) of the above-described grooves and the like fall within the above ranges. For example, the thickness of the adhesive layer is usually 10 to 200 μm.
m, preferably 15 to 100 μm, and the depth of the groove (the distance from the adhesive surface to the bottom of the groove measured in the direction of the substrate) is usually 10 to 100 μm. By the way, when there are a plurality of grooves spaced apart from each other at a predetermined interval and arranged in parallel with each other as in the adhesive sheet of the present invention, the grooves are formed from the surface of the base material in a state of being bonded to the adherend surface. Pattern is easy to see. In particular, it has been found that such pattern recognition becomes remarkable when the substrate includes a metal layer and has a metallic luster. Therefore, as a result of the examination, it was found that the pattern visibility can be more effectively prevented as the groove depth and the arrangement interval of the grooves are smaller within a certain range. Therefore, it is preferable to design the depth of the groove and the arrangement interval of the groove in consideration of such a viewpoint. That is, the depth of the groove is preferably 11 to 50 μm, particularly preferably 12 to 20 μm. The arrangement interval of the grooves is preferably 50 to 400 in order to effectively prevent both pattern recognition and sheet swelling.
μm, particularly preferably 100 to 300 μm.

On the other hand, the shape of the groove is not particularly limited as long as the effects of the present invention are not impaired. For example, the cross section of the groove in a direction perpendicular to the bonding surface is substantially rectangular (including a trapezoid), substantially semicircular, or substantially semielliptical. Further, the shape of the convex portion that defines the groove is not particularly limited. For example, the cross section of the groove in a direction perpendicular to the bonding surface is substantially rectangular, substantially semicircular, or substantially semielliptical. For example, when the shape of the cross section in the direction perpendicular to the bonding surface of the protrusion is substantially rectangular, the three-dimensional shape of the protrusion is generally a prism such as a square pole, a cylinder (including an elliptic cylinder), or a truncated pyramid. And the like, a truncated pyramid, a truncated cone (including an elliptical truncated cone), and the like.

The top surface (adhesion surface to the adhered surface) of the projection is
At least one having a horizontal cross-sectional area smaller than an area of the substantially flat top surface may be substantially flat or substantially at the center of the top surface.
It may have two small projections. Note that such small projections are formed integrally with the projections and can be made of an adhesive of an adhesive layer, or microspheres (beads) made of glass or polymer are embedded in the projections to form the small projections. You may.

The adhesive layer is usually formed by applying and solidifying a paint containing an adhesive as described later. Solidification means include:
Drying, curing, cooling (when the paint is a molten liquid) and the like can be used. The application means is an application using a roll coater, a knife coater, a bar coater, a die coater, or the like, or a printing means such as screen printing or gravure printing. The adhesive layer
It is preferable to apply an adhesive paint on the liner release surface having a release surface having a predetermined uneven structure, in the same manner as in the related art, except that the dimensions of the grooves and the like of the adhesive layer are different. Thereby, the uneven structure (negative structure) of the liner is transferred to the surface of the adhesive layer that is in contact with the liner (the adhesive surface of the adhesive sheet),
An uneven bonding surface having a predetermined structure (positive structure) can be easily formed on the bonding surface. In addition, in this way, after providing the adhesive layer on the back surface of the base material, the liner is pressed in contact,
This is advantageous in that the deformation of the uneven structure including the groove of the adhesive layer can be effectively prevented as compared with the case where the liner uneven structure is transferred to the adhesive surface. That is, it is possible to effectively prevent the uneven structure from being deformed after being bonded to the adherend and the channel from being crushed or lost.

As the liner, a liner similar to the conventional one can be used except that the size of the concavo-convex structure to be transferred to the adhesive layer is different. For example, the liner is formed from paper or plastic film. The paper liner is usually formed by laminating a release coat (release layer) such as a polyethylene coat or a silicone coat on the surface of paper. When laminating a silicone release coat, usually, an undercoat such as a clay coat or a polyethylene coat is laminated on paper, and then a release coat is laminated. The uneven structure of the liner can be usually formed by laminating a release coat and then pressing the uneven transfer tool against the release surface.

(Adhesive) As described above, the protrusions of the adhesive layer are formed from an adhesive. The adhesive usually contains a tacky polymer. In addition to the adhesive polymer, a non-adhesive polymer such as a crystalline polymer may be contained. The adhesive of the adhesive layer preferably contains a tacky polymer and a crosslinking agent. The content of the crosslinking agent is usually 0.1 to 5 parts by mass, preferably 0.15 to 3 parts by mass with respect to 100 parts by mass of the adhesive polymer. If the amount of the cross-linking agent is too small, the convex portion of the adhesive layer is deformed by the external stimulus such as heat or pressure, or naturally over time, after being attached to the adherend, and the channel collapses or disappears. There is a risk. Conversely, if the amount of the crosslinking agent is too large, the adhesive strength (peel strength) of the adhesive layer decreases,
When used outdoors for a relatively long period of time, the effect of maintaining adhesion is reduced, and there is a possibility that sheet swelling due to outgassing cannot be prevented.

The tacky polymer used in the present invention is a polymer that exhibits tackiness at room temperature and can be used as a pressure-sensitive adhesive. As such a polymer, an acrylic polymer, polyurethane, polyolefin, polyester, or the like can be used. In addition, a tackifier can be used together with a tacky polymer, similarly to a conventionally known pressure-sensitive adhesive.

An example of synthesizing the adhesive polymer will be described by taking an acrylic polymer as an example. First, an acrylic unsaturated acid (for example, acrylic acid, methacrylic acid, itaconic acid, maleic acid, etc.) is prepared as the first monomer. This first monomer and an acrylic monomer as the second monomer are mixed to prepare a monomer mixture.
As the second monomer, an alkyl acrylate, for example, isooctyl acrylate, butyl acrylate,
2-ethylhexyl acrylate, isononyl acrylate and the like can be used. The first component contained in the monomer mixture
The (weight) ratio of monomer to second monomer is preferably
The range is from 1:99 to 10:90. The monomer mixture thus prepared is polymerized by a usual polymerization method, for example, solution polymerization, emulsion polymerization, bulk polymerization, or the like, to synthesize a tacky polymer having a predetermined molecular weight. The molecular weight of the pressure-sensitive adhesive polymer may be within a range in which a predetermined pressure-sensitive adhesiveness is exhibited, and is usually 10,000 to 100,000 in weight average molecular weight.
00 range.

When the adhesive polymer is crosslinked, for example, dibasic acids such as isocyanate compounds, melamine compounds, poly (meth) acrylate compounds, epoxy compounds, amide compounds, and bisamide compounds (isophthaloylbis (2-methylaziridine)) Bis aziridine derivative)
And the like can be used as a crosslinking agent.

Although the elastic modulus of the adhesive layer is not particularly limited, it is preferable to prevent the disappearance of the groove (channel) and not to unnecessarily reduce the peel strength. For example, temperature 85
℃, the dynamic elastic modulus at a shear frequency of 1 rad / sec is 1
× 10 ^{4 to} 9 × 10 ⁴ dyne / cm ² (1 to 9 kP
a) is preferred. If the dynamic elastic modulus of the adhesive layer is too high, the adhesiveness of the adhesive sheet to the surface to be adhered may be reduced. Conversely, if the dynamic elastic modulus is too low, the channel holding effect of the adhesive layer may be reduced. From such a viewpoint, the dynamic elastic modulus (at 85 ° C.) of the adhesive layer of the adhesive sheet is particularly preferably 2 × 10 ⁴ to 8 × 10 ⁴ dy.
ne / cm ² ( ^{2 to} 8 kPa). The “dynamic elastic modulus” is a dynamic elastic modulus measured at 85 ° C. using an RSAII viscoelastic spectrometer manufactured by Rheometrics. That is, while giving a shear strain of a frequency of 1 rad / sec, the temperature was changed in the range of -80 ° C to 150 ° C, and the temperature dependence of the dynamic elastic modulus was measured. And

Although the compression modulus of the adhesive layer is not particularly limited, it is preferably 1 × 1 to prevent the disappearance of the groove (channel) and to prevent the peel strength from excessively decreasing.
^{0 4 ~1 × 10 6 dyne /} cm 2 range are good. The "compression modulus" is a compression modulus measured at 20 DEG C. using an RSAII viscoelastic spectrometer manufactured by Rheometrics. That is, the temperature is changed in the range of -80 ° C to 150 ° C while applying compressive strain at a frequency of 1 rad / sec, the temperature dependence of the elastic modulus is measured, and the measured value at 20 ° C is defined as the compressive elastic modulus.

The adhesive layer may contain components other than the adhesive polymer and the crosslinking agent, as long as the effects of the present invention (particularly, the effect of preventing swelling due to outgassing) are not impaired. For example, it can contain elastic microspheres formed from a polymer. When the elastic microspheres include an adhesive polymer, the adhesion of the adhesive layer to the adherend can be enhanced. In addition, when the adhesive layer contains glass microspheres, before the bonding of the adhesive sheet is completed, the adhesive sheet is slid sideways while being placed on the adherend to facilitate positioning, so-called slidability (ease). of slide) can be effectively enhanced. The diameter of the glass microsphere is usually
It is preferable that the value be smaller than the maximum value of the plane dimension of the bonding surface (for example, when the bonding surface is rectangular, the length of a diagonal line thereof).

Further, a polymer other than the adhesive polymer,
For example, it may contain a crystalline polymer (usually non-tacky at room temperature, about 25 ° C.). The crystalline polymer can also provide the adhesive layer with slidability, ease of heating / peeling (a property that peel strength decreases when heated), and the like. As the crystalline polymer, for example, a polyester such as polycaprolactone, a polyurethane obtained by chain-extending a polyester with an isocyanate compound, or the like can be used.

(Substrate) In the adhesive sheet of the present invention, the substrate is not limited. In particular, according to the present invention, an adhesive sheet that can be used outdoors can be provided even when a substrate having a relatively low gas permeability such as water vapor is used. A substrate having a low gas permeability such as water vapor usually has a moisture permeability of 0.01 to 30 [g / m ² · 2, measured according to JIS Z0208.
4 hours—thickness 30 μm−40 ° C./90% RH]. Such a substrate having a relatively low water vapor transmission rate has an effect that moisture (water vapor from the outside) reaches the adherend through the surface of the adhesive sheet (substrate surface) and absorbs moisture. Can be prevented. However, when a substrate having a relatively low water vapor transmission rate and an adhesive layer of a conventional adhesive sheet are combined, sheet swelling due to outgas from the adherend is likely to occur. Therefore, when a substrate having such a low water vapor transmission rate is used, the above-mentioned adhesive layer should be used according to the present invention. The moisture permeability of the base material is preferably 0.
1~25 [g ^{/ m} 2 · 24 hours - thickness 30 [mu] m-40 ° C.
· 90% RH], particularly preferably 1~20 [g ^{/ m} 2 · 2
4 hours—thickness 30 μm-40 ° C. 90% RH]. As such a base material having low moisture permeability, fluorine resin,
A low moisture-permeable resin layer containing at least one selected from the group consisting of polyvinylidene chloride and polyolefin,
Alternatively, a film including a metal layer may be used. As the polyolefin, for example, polyethylene, polypropylene, ionomer, ethylene-vinyl acetate copolymer and the like can be used. One of the base materials that can be suitably used in the present invention
As an example, a material containing a layer containing a fluororesin (fluororesin) can be given. A substrate comprising a layer containing a fluorine resin can effectively enhance the weather resistance of the adhesive sheet, but has a relatively low water vapor transmission rate, and when the adhesive layer of the conventional adhesive sheet is diverted as it is, Sheet swelling due to outgas is likely to occur. Therefore, when a substrate including a layer containing a fluororesin is used, the above-described adhesive layer should be used according to the present invention.

Such a base material is, for example, a base material including a clear coat layer containing a fluororesin and a protective layer on the outermost layer in direct contact with the outside air. Such a base material is generally formed by laminating a clear coat layer or a protective layer containing a fluororesin on a fluororesin or a resin other than the fluororesin, or a support layer containing a metal layer. Fluororesin layers such as a clear coat layer and a protective layer can be usually formed by applying and solidifying (drying, curing, etc.) a coating containing a fluororesin by an ordinary method. Fluororesin, for example, vinylidene fluoride,
It consists of a polymer obtained by polymerizing a starting monomer containing at least one fluorine-based monomer such as propylene hexafluoride, ethylene tetrafluoride and ethylene trifluoride chloride. In addition, the starting monomer may contain, in addition to the fluorine-based monomer, another copolymerizable monomer, for example, an acrylic monomer such as methyl methacrylate or ethyl methacrylate.

Further, the fluorine resin layer may contain a non-fluorine resin in addition to the fluorine resin. As the non-fluorine resin, an acrylic resin is preferable. In such a case, the ratio of the fluororesin to the whole resin is usually 5%.
It is at least 5% by mass, preferably at least 60% by mass. If the amount of the fluororesin is too small, the weather resistance may decrease. The thickness of the fluororesin layer is usually in the range of 1 to 300 μm, preferably in the range of 3 to 200 μm.

The resin used for the support layer on which the fluororesin layer is laminated is, in addition to the fluororesin, an acrylic resin,
Examples thereof include a vinyl chloride resin, a polyester resin, a polyurethane resin, and an epoxy resin. Also. The metal layer included in the support layer is a thin film or a metal foil formed by evaporating a metal such as aluminum, tin, chromium, copper, gold, and silver. Also,
A multilayer film in which these resin layers and metal layers are laminated,
It may be used as a support layer. The thickness of the entire support layer is not particularly limited, and is usually 5 μm to 1 mm.

As another example of a substrate that can be suitably used in the present invention, a substrate containing a metal layer can be mentioned. The base material including the metal layer can impart a metallic appearance to the adhesive sheet, but has almost no water vapor transmission rate, and when the adhesive layer of the conventional adhesive sheet is diverted as it is, the sheet swells due to outgas. Likely to happen. Therefore, when a substrate including a metal layer is used, the above-mentioned adhesive layer should be used according to the present invention.

The substrate containing a metal layer is usually a multilayer film in which a metal layer is laminated on the front or back surface of a support layer containing a resin. Further, it is preferable to use a substrate having a laminated structure in which an outermost layer such as a clear coat layer and a protective layer is further provided on the metal layer and the metal layer is sandwiched between two layers. Note that another layer can be added in addition to the three-layer structure described above. As the metal layer, a thin film formed by evaporating a metal such as aluminum, tin, chromium, copper, gold, and silver, or a metal foil can be used. The thickness of the metal layer is not particularly limited, but is usually 50 nm to 500 μm.

The support layer on which the metal layer is laminated is usually a resin layer containing a fluororesin as described above or a non-fluorine resin (such as an acrylic resin). The thickness of the support layer is not particularly limited, and is usually 5 μm to 1 mm. The outermost layers such as the clear coat layer and the protective layer are usually coated with a paint containing a fluororesin or an acrylic resin by a usual method, and solidified (dried,
Curing and the like). Although the thickness of the outermost layer is not particularly limited, it is usually 1 to 500 μm.

(Adherend) The adherend used in the adhesive structure according to the present invention is not particularly limited. However, according to the present invention, even if the adherend is likely to generate a relatively large amount of outgas, the blister of the sheet can be effectively prevented. Therefore, when using an adherend that contains a substance that is relatively easily absorbed by moisture and that is used outdoors for a relatively long time (that is, continuously in a relatively high temperature environment), the adhesive layer of the present invention is used. Is preferable in that a particularly remarkable effect is exhibited. The adherend that is relatively easy to absorb moisture is, for example,
The water absorption is determined to be 0.2% or more by measuring the rate of weight increase after immersion in water at 23 ° C. for 24 hours by a method based on TM D570, and outgas such as water vapor is easily generated. .

Examples of such adherends include plastics, such as polycarbonate, which have a relatively high moisture absorption and easily generate outgas such as water vapor. When polycarbonate is used as the adherend, its grade and thickness are not particularly limited. For example, the thickness is usually 2-10
mm. The adherend containing such a polycarbonate is used, for example, as a component such as a tank of a motorcycle or a component such as a board of a signboard.

[0040]

EXAMPLES (Example 1) Acrylic adhesive polymer was added to 1
An adhesive solution was obtained by adding 0.3 parts by mass of a bisamide compound as a crosslinking agent to a solution containing 00 parts by mass. In addition,
Acrylic adhesive polymer is butyl acrylate, 2
-An acrylic copolymer obtained by polymerizing a monomer mixture containing ethylhexyl acrylate and acrylic acid as main components. The crosslinking agent reacts with the carboxyl group of the acrylic adhesive polymer and crosslinks the adhesive polymer in the adhesive layer. The dynamic elastic modulus of the adhesive layer at 85 ° C. was 4 × 10 ⁴ dyne / cm ² (4.0
kPa). The dynamic elastic modulus was read from a viscoelastic spectrum measured in a shear mode by a dynamic viscoelasticity measurement method using a dynamic analyzer (model number) RDAII manufactured by Rheometrics. The shear frequency was 1 rad / sec.

The above adhesive solution is applied on the release surface of a liner having a release surface on which irregularities of a predetermined shape and size are formed, and dried at 90 ° C. for 5 minutes. Formed an adhesive layer having a thickness of 30 μm. The adhesive layer and the substrate were dry-laminated to obtain an adhesive sheet of this example. The base material was a 50 μm-thick polyvinylidene fluoride film and an aluminum vapor-deposited layer (about 50 n thick).
m). The adhesive layer was fixed on the aluminum deposition surface.

The moisture permeability of the substrate used in this example was 15 g / g
m ² · 24 hours - thickness 30μm-40 ℃ · 90% RH ]
Met. The moisture permeability of the substrate was measured as follows in accordance with JIS Z0208. First, internal volume 200cm
The aluminum can of No. ³ was prepared, and 2 g of calcium chloride was put therein. Next, a substrate for measuring moisture permeability was prepared as a sample, the opening of the aluminum can was closed with the sample, and the can and the sample were bonded and sealed with a sealing agent. The sealed can was allowed to stand in a constant temperature and humidity oven at 40 ° C. and 90% RH for 24 hours, and the increased mass of the sealed can was measured and converted to moisture permeability. The aluminum can used here was a cylindrical aluminum can manufactured by Saito Can Co., Ltd., calcium chloride was calcium chloride for moisture measurement manufactured by Kanto Kagaku Co., Ltd., and the sealing agent was modified silicone sealing manufactured by Konishi Co., Ltd. Agent (Part No .: M
PX-1), and the thermo-hygrostat was a thermo-hygrostat (product number: IH-42M) manufactured by Yamato Scientific Co., Ltd.

The liner was formed by laminating an undercoat made of polyethylene on both sides of paper and laminating a silicone release coat on the undercoat.
m paper liner. On the peeling surface, convex portions composed of a plurality of ridges corresponding to the grooves to be transferred to the adhesive layer were arranged continuously along a cross-cut line so as to cross each other. The height of the ridge was 15 μm (the depth of the groove measured from the bonding surface was also 15 μm). The center-to-center distance between adjacent ridges (corresponding to the arrangement interval of the grooves formed in the adhesive layer) was 200 μm. Further, the vertical cross-sectional shape of the ridge was substantially trapezoidal, and correspondingly, the groove of the adhesive layer had a substantially trapezoidal vertical cross-sectional shape.

The channel volume formed when the adhesive sheet obtained as described above was adhered to the adherend was determined as follows. First, instead of the base material, the thickness is 50 μm.
A measurement sheet was prepared in the same manner as described above, except that a light-transmissive polyvinyl chloride film was used. The liner was peeled off from the sheet for measurement, the adhesive surface was placed on the surface of the slide glass, and the sheet was pressed back and forth three times with a 2 kg roller to obtain a sample for measurement. In this measurement sample, all the channels defined by the groove and the adhered surface were in communication with the outside at the end of the sheet.
Immediately after the measurement sheet is pressed, white light is illuminated from the side of the slide glass opposite to the side to which the measurement sheet is adhered, and observed through a polarizing plate. The area where the adhesive and the glass surface are bonded looks dark, and the non-bonded area looks whitish. The observation result is analyzed using an image processing apparatus, and the area of the non-adhesion region is measured. The area of the non-adhesion region is the area (P) of the channel on the adhered surface side.

On the other hand, using the sample for measurement,
White light is illuminated from the substrate side of the measurement sheet, and observation is performed in the same manner as described above. The region where the adhesive layer adheres to the glass surface looks black, and the non-adhered region looks whitish. The observation result is analyzed in the same manner as described above, and the area of the non-adhesion region is measured. The area of the non-adhesive region is the area of the channel on the adhesive layer side (the area at the bottom of the groove = Q).

Further, a vertical section of the measuring sheet after bonding
(Cross section perpendicular to the surface to be adhered) with a microscope
The height (H) of the channel is measured. From these measurements,
Arithmetic (using formula (P + Q) × H / 2), apparent
Adhesion area of 1mm²Per channel volume
1.3 × 10 ⁶μm³(1.3 × 10^-3m
m³)Met. This value is used for the adhesive sheet of this example.
Initially measured channel volume adhered to adherend
Was set to the value In.

On the other hand, the above-mentioned measurement sample was heated at 85 ° C. for 30 minutes.
After heating for one minute, the volume of the channel (per 1 mm ^{2 of} apparent adhesive area) was determined in the same manner as above. as a result,
It was 1.2 × 10 ⁶ μm ³ (1.2 × 10 ⁻³ mm ³ ). This value was taken as the value Ah of the channel volume of the adhesive sheet of this example, which was measured after bonding to the adherend and heating at 85 ° C. for 30 minutes. In the above measurement, as a slide glass, a part number S-1 manufactured by Matsunami Corporation was used.
111, and Nippon Avionics as an image processing device
EXCEL TVIP-4100 manufactured by Incorporated was used.

On the other hand, the adhesive sheet of the present example obtained as described above was used as a polycarbonate plate (manufactured by Teijin Chemicals, product number PC81
21, thickness 3 mm) under the same conditions as in the above-mentioned channel volume measurement, and cured at room temperature (about 25 ° C.) for one day. After curing, it was heated for 30 minutes in ovens set at 65 ° C and 85 ° C, respectively. After heating, it was taken out of the oven, and the degree of swelling of the adhesive sheet surface was observed from the substrate side. As a result of the observation, no swelling was observed even after heating at 65 ° C. and after heating at 85 ° C.

Example 2 The arrangement interval of the grooves formed in the adhesive layer was 254 μm, and the initial value In of the channel volume was 1.
An adhesive sheet of this example was obtained in the same manner as in Example 1, except that the dimensions of the irregularities on the liner release surface were changed so as to be 4 × 10 ⁶ μm ³ . In the adhesive sheet of this example, the value Ah of the channel volume after heating was 1.2 × 10 ⁶ μm ³ . The depth of the groove measured from the bonding surface is 16 μm
Met. The adhesive sheet of this example was made in the same manner as in Example 1,
Pressure bonding to the above polycarbonate plate, normal temperature (about 25 ° C)
After curing for 1 day, the degree of swelling of the surface of the adhesive sheet when heated in an oven for 30 minutes was observed. As a result of observation,
No swelling was observed even after heating at 65 ° C and after heating at 85 ° C.

Example 3 The arrangement interval of the grooves formed in the adhesive layer was 508 μm, and the initial value In of the channel volume was 8.
An adhesive sheet of this example was obtained in the same manner as in Example 1 except that the dimensions of the irregularities on the liner release surface were changed so as to be 7 × 10 ⁵ μm ³⁻ . In the adhesive sheet of this example, the value Ah of the channel volume after heating was 8.0 × 10 ⁵ μm ³ . The depth of the groove measured from the bonding surface is 18 μm.
m. The adhesive sheet of this example was pressure-bonded to the above-mentioned polycarbonate plate in the same manner as in Example 1, and was subjected to room temperature (about 25
C.) for one day, and then observed the degree of swelling of the surface of the adhesive sheet when heated in an oven for 30 minutes. As a result of the observation, no swelling was observed even after heating at 65 ° C and after heating at 85 ° C.

(Comparative Example 1) Dimensions of the irregularities on the liner release surface so that the arrangement interval of the grooves formed in the adhesive layer is 1,270 μm and the initial value In of the channel volume is 2.3 × 10 ⁶ μm ^3. The adhesive sheet of the present example was obtained in the same manner as in Example 1 except that was changed. In the adhesive sheet of this example, the value Ah of the channel volume after heating was 2.1 × 10 ⁶ μm ³
Met. The depth of the groove measured from the bonding surface is 27
μm. The adhesive sheet of this example was pressure-bonded to the above-mentioned polycarbonate plate in the same manner as in Example 1, and was subjected to room temperature (about 25
C.) for one day, and then observed the degree of swelling of the surface of the adhesive sheet when heated in an oven for 30 minutes. As a result, no swelling was observed at 65 ° C.
After heating at 5 ° C., many blisters were observed, and the appearance was significantly impaired.

(Comparative Example 2) The arrangement interval of the grooves formed in the adhesive layer was 600 μm, and the initial value In of the channel volume was 1.
An adhesive sheet of this example was obtained in the same manner as in Example 1, except that the dimensions of the irregularities on the liner release surface were changed so as to be 4 × 10 ⁷ μm ³ . The depth of the groove measured from the bonding surface was 50 μm. The adhesive sheet of this example was pressed against the above-mentioned polycarbonate plate in the same manner as in Example 1, cured at room temperature (about 25 ° C.) for one day, and then swelled on the surface of the adhesive sheet when heated in an oven for 30 minutes. The degree was observed.
As a result of observation, only fine swelling was observed at 65 ° C., but after heating at 85 ° C., many swellings were observed, and the appearance was significantly impaired.

In the adhesive sheet of this embodiment, a channel having a relatively large volume can be formed. Therefore, it is considered that the gas generated from the adherend is relatively easy to escape. However, since the groove spacing is relatively large and the volume of the channel is relatively large, the bonding area (real bonding area) is considerably smaller than that in Example 1, so that the heating temperature increases and the gas generation rate increases. It was found that when the ratio was relatively high, swelling occurred.

(Comparative Example 3) The substrate was changed to a polyvinyl chloride film (having a thickness of 50 μm) having no metal deposition layer.
Other than changing the liner to one with a flat release surface,
An adhesive sheet of this example was obtained in the same manner as in Example 1. The adhesive sheet of this example was pressed against the above-mentioned polycarbonate plate in the same manner as in Example 1, cured at room temperature (about 25 ° C.) for one day, and then swelled on the surface of the adhesive sheet when heated in an oven for 30 minutes. The degree was observed. As a result of observation, 65 ° C. and 8
At both temperatures of 5 ° C., a number of blisters were observed after heating, and the appearance was significantly impaired.

Example 4 The arrangement interval of the grooves formed in the adhesive layer was 450 μm, and the initial value In of the channel volume was 1.
An adhesive sheet of this example was obtained in the same manner as in Example 1, except that the dimensions of the irregularities on the liner release surface were changed so as to be 5 × 10 ⁷ μm ³ . In the adhesive sheet of this example, the value Ah of the channel volume after heating was 1.4 × 10 ⁷ μm ³ . The depth of the groove measured from the bonding surface was 25 μm
Met. The adhesive sheet of this example was made in the same manner as in Example 1,
Pressure bonding to the above polycarbonate plate, normal temperature (about 25 ° C)
After curing for 1 day, the degree of swelling of the surface of the adhesive sheet when heated in an oven for 30 minutes was observed. As a result of observation,
No swelling was observed even after heating at 65 ° C and after heating at 85 ° C.

(Pattern Visual Recognition Test) The adhesive sheets of Examples 1 to 4 and Comparative Examples 1 and 2 were pressure-bonded to a polycarbonate plate in the same manner as described above, and were subjected to room temperature (about 25
C.) for one day, and visually observed from the surface of the base material to check whether or not the repetitive pattern of grooves was visible. As a result, in the adhesive sheets of Example 3, Example 4, Comparative Examples 1 and 2 having relatively large groove intervals, the repeated pattern of the grooves was visually recognized. On the other hand, in the adhesive sheets of Examples 1 and 2 having a relatively small groove interval, it was found that the repeated pattern of the grooves was hardly visually recognized.

 ──────────────────────────────────────────────────の Continued on the front page F term (reference) 4F100 AB01A AB10 AK03A AK16A AK17A AK19 AK25G AK45C AR00C AT00A BA02 BA03 BA07 BA10A BA10C CA02 DD05B GB32 GB90 JD04A JL11B YY00A YY00B 4J004 AA07 AA03 AA03 AA03 DA04 DB02 DB03 EA06 FA10 4J040 DA001 DF041 EB132 ED001 EF001 EF261 HC10 JA09 JB09 KA16 PA23

Claims (6)

[Claims] An adhesive layer fixedly disposed on a back surface of the substrate, wherein the adhesive layer has a plurality of grooves arranged on the adhesive surface at predetermined intervals. An adhesive sheet having a channel that communicates with the outside defined by the groove and the adhered surface when the adhesive sheet is adhered to the adhered surface of the adherend, wherein an arrangement interval of the groove is 10 to 520 μm; The adhesive sheet, wherein the channel exists even after the adhesive sheet is bonded to the adherend and heated at 85 ° C. for 30 minutes. 2. The adhesive sheet according to claim 1, wherein the grooves are arranged substantially parallel to each other. 3. The volume of the channel is measured after the adhesive sheet is bonded to the adherend at an early stage, and after the adhesive sheet is adhered to the adherend and heated at 85 ° C. for 30 minutes. Both values Ah have an apparent adhesion area of 1 mm ²
The adhesive sheet according to claim 1, wherein a measured value per unit is in a range of 1 × 10 ⁵ to 2 × 10 ⁷ μm ³ . Claim 1
Adhesive sheet. 4. The substrate has a moisture permeability of 0.01 to 30 [g / m ² · 24 measured according to JIS Z0208.
2. The adhesive sheet according to claim 1, wherein the time is in the range of 30 μm to 40 ° C. and 90% RH]. 5. The method according to claim 4, wherein the base material comprises a resin layer having a low moisture permeability containing at least one selected from the group consisting of a fluororesin, polyvinylidene chloride and polyolefin, or a metal layer. The adhesive sheet according to the above. 6. An adhesive structure, comprising: an adherend comprising polycarbonate; and the adhesive sheet according to claim 1 adhered to an adherend surface of the adherend.