JPH09157606A - Pressure-sensitive adhesive sheet, its production and pressure-sensitive adhesive sheet stick structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a tacky sheet excellent in adhesion performances even when stuck to a material to be bonded having an uneven surface.

SOLUTION: This tacky sheet comprises a substrate and a tacky layer containing very small tacky elastic spheres and a tacky polymer formed on the substrate. The tacky layer has projected tacky parts in an irregular shape containing clusters formed by at least two collected very small spheres and the tacky polymer. The area contact ratio between the tacky layer and a flat glass plate is 20-90% and a wetting exponent on the surface of the substrate is preferably 35-70dyne/cm² when the tacky sheet is stuck to the surface of the glass plate under 1kg/cm pressure.

COPYRIGHT: (C)1997,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive sheet of a type containing elastic microspheres in an adhesive layer, which is attached to an adherend having an uneven surface, a method for producing the same, and an adhesive sheet sticking structure, and more particularly, mortar. The present invention relates to a pressure-sensitive adhesive sheet capable of exhibiting good adhesion performance when used by adhering to an adherend surface facing the outdoors, such as a building outer wall made of concrete.

[0002]

2. Description of the Related Art As an adhesive sheet (generally referred to as "adhesive film") such as a decorative sheet or a retroreflective sheet, which is attached to an adherend having an uneven surface such as a wall surface, for example, the following (a): Adhesive sheets of the types described in (d) are known. (A) The adhesive sheet disclosed in JP-A-2-32180 comprises a support made of non-woven fabric and a flexible resin, and an adhesive coated on the support. In this adhesive sheet, the use of a support having good flexibility as described above
It is intended to improve the conformability to the uneven surface of the adherend.
However, when it is used outdoors by sticking it to a porous adherend such as mortar and concrete, water that has penetrated into the adherend, or steam containing water, will form at the interface between the adherend and the adhesive layer. It leaches out and cannot escape from it, causing swelling of the adhesive layer and sheet due to its osmotic pressure. Further, since the surface of the support is very rough, it is difficult to give a decoration by printing or the like to the surface.

(B) The releasable pressure-sensitive adhesive tape disclosed in Japanese Utility Model Laid-Open No. 5-72946 discloses a support, a viscoelastic layer provided on the support, and a viscoelastic layer. It is laminated with the provided adhesive layer containing spherical fine particles. This adhesive tape is intended to improve the followability to the uneven surface of the adherend by the action of the viscoelastic body layer. However,
Since the average particle diameter of the spherical fine particles used is as small as 1 to 10 μm, the adhesiveness to the surface of the adherend having a relatively large degree of irregularities such as mortar and concrete is not sufficient.
Moreover, since it is necessary to additionally provide a specific viscoelastic layer, the manufacturing process tends to be complicated. Here, "degree of unevenness"
Is defined as surface roughness, for example, JIS B 0
601 (1994), the arithmetic mean roughness (Ra) at a cutoff value of 8 mm and an evaluation length of 40 mm is about 20-.
The case of 100 μm is called a “surface with a relatively large degree of unevenness” or a “rough surface”.

(C) The pressure-sensitive adhesive sheets disclosed in JP-A-7-3222 and JP-A-7-48549 generally include a photo-cured pressure-sensitive adhesive layer and a low-content pressure-sensitive adhesive layer contained therein. Energy-comprising surface-treated microspheres. In this pressure-sensitive adhesive sheet, non-adhesive microspheres having an average diameter of 5 to 200 μm are surface-treated to facilitate the movement of the microspheres in the pressure-sensitive adhesive layer at the time of sticking and to adhere them. It is intended to improve the ability to follow the uneven surface of the body. However, in this case, since the microspheres are eventually buried in the adhesive layer and the convex portion is not formed, the adhesiveness to the uneven surface cannot be improved.

(D) The pressure-sensitive adhesive tape disclosed in Japanese Utility Model Laid-Open No. 1-70848 has a support tape provided with a pressure-sensitive adhesive having a relatively regular irregular shape such as a mesh pattern. It is difficult to form such regular irregularities, and the adhesive area is always effectively increased for adherends such as mortar and concrete which are not always regular irregular surfaces. I can't.

On the other hand, as an adhesive sheet provided with an adhesive layer containing adhesive elastic microspheres, for example, the following (e)
Adhesive sheets of the types shown in (f) and (f) are known. (E) The pressure-sensitive adhesive film disclosed in Japanese Patent Laid-Open No. 6-287525 has a structure in which a pressure-sensitive adhesive elastic microsphere having a volume average diameter of 100 to 300 μm and a pressure-sensitive adhesive layer made of a pressure-sensitive adhesive are provided on a film substrate. The air trapped between the film and the flat adherend during application can be successfully escaped. The elastic microspheres are contained in the pressure-sensitive adhesive in a monodisperse state or a so-called “cluster state” (definition will be described later) in which two or more elastic microspheres are aggregated and dispersed as microspheres.
When the elastic microspheres are contained in a monodisperse state, a sufficient degree of adhesion to the surface of the adherend such as mortar and concrete, which has a relatively large degree of unevenness and has irregularities and irregularly arranged unevenness. Can't get This disclosure statement
It is also suggested that the formation of clusters of elastic microspheres is advantageous for bubble escape, but no limitation on clusters having excellent adhesion to an uneven surface, and a method for forming clusters useful therefor are disclosed.

(F) The removable pressure-sensitive adhesive body disclosed in JP-A-6-172739 has an average particle diameter of 1 to 200 μm.
Of the adhesive particles, or the particles and a non-adhesive binder. This adhesive has a structure that does not include a film-like support, and it has not been suggested that elastic microspheres form clusters. The formation of such an adhesive body does not use a means for directly coating it on a support, so it is extremely difficult to form a cluster of adhesive fine particles, and the absence of an adhesive polymer results in efficient formation of a cluster. Making it difficult to do.

1) In US Pat. No. 5,141,790, a projection having a substantially uniform distribution on at least one surface of a pressure-sensitive adhesive layer has a large number of particle groups at its tip. A positionable adhesive tape having a structure including is disclosed. Since the particles are non-adhesive such as glass beads and the convex portions are uniformly distributed, they have good removability. 2) U.S. Pat. No. 4,054,697 discloses a decorative material including a continuous pressure sensitive adhesive layer and a non-continuous, non-sticky layer of elastic microspheres. When this decorative material is pressure-bonded to an adherend, the layer of elastic microspheres is deformed and more completely adheres to the adherend. 3) U.S. Pat. No. 4,556,595 discloses a pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer has a particle size of less than the thickness of the layer and less than 1 μm and contains non-adhesive solid particles. It is disclosed. Calcium carbonate or the like can be used for the non-adhesive solid particles, whereby the adhesive force can be controlled in a relatively low range. 4) U.S. Pat. No. 5,296,277 discloses a position-adjustable adhesive layer having a geometric shape and arrangement and having fine protrusions containing at least one or more fine particles such as glass beads. An adhesive article is disclosed. In this adhesive article, the projection has a smooth top, and the total contact area between the adhesive article and the adherend after attachment is 1 to
It is designed to be reduced to the range of 25%. With such a configuration, the re-peeling performance at a level where the position can be easily adjusted is exhibited. 5) JP-A-1-118584 discloses a position-adjustable pressure-sensitive adhesive including a pressure-sensitive adhesive layer having non-adhesive fine particles having an average particle diameter of 10 to 60 μm partially projected on the surface thereof. An adhesive sheet is disclosed. 6) US Pat. No. 5,109,083 discloses that it is insoluble,
Disclosed is a method of preparing a suspension that is insoluble in a solvent, dispersible in the solvent, and comprises a cluster of elastic microspheres that are self-adhesive. That is, in the suspension, the elastic microspheres have already formed clusters, and by applying such a suspension,
A reusable (that is, removable) pressure-sensitive adhesive sheet can be formed. However, no mention is made of improvement in adhesive strength to an adherend such as mortar. 7) Japanese Patent Application No. 6-243079 by the applicant of the present application,
The elastic modulus of the film base material is 10 ⁴ to 10 ⁷ dyn.
A pressure-sensitive adhesive film having a pressure-sensitive adhesive layer formed by coating a pressure-sensitive adhesive containing microspheres having a volume average diameter of 10 to 100 μm / cm ² is disclosed. This pressure-sensitive adhesive film can improve the escape of bubbles taken in between the film and the flat adherend surface, as in the above-mentioned JP-A-6-287525.
Furthermore, it has excellent removability, that is, an adhesive strength of 20
It is controlled within a relatively low range of 0 to 1,000 kg / 25 mm.

[0009]

As described above, the conventional pressure-sensitive adhesive sheet is an adherend such as mortar and concrete which has a relatively large degree of irregularities and has irregularities of irregular shape and arrangement. It was not possible to obtain a sufficient adhesive force to the rough surface, and as a result, the pressure-sensitive adhesive sheet sometimes peeled from the adherend over time. Further, since mortar and concrete are water-absorbing porous materials, when an adhesive sheet is attached to the mortar and concrete, leaching to the bonding interface of water-containing steam that has entered the inside of the adherend from the outside The pressure-sensitive adhesive layer sometimes swells, and as a result, the pressure-sensitive adhesive sheet may peel off from the adherend.

In view of the above problems, one object of the present invention is to provide a relatively large degree of irregularities such as mortar and concrete, have irregular shapes and irregularities, and absorb water. A pressure-sensitive adhesive sheet that retains sufficient adhesive force for a long time to an adherend containing a porous body and prevents the pressure-sensitive adhesive layer from swelling due to steam containing water leached from the inside of the adherend to the adhesive interface. To provide. Another object of the present invention is to provide a method for producing a pressure-sensitive adhesive sheet, which is capable of effectively forming clusters of elastic microspheres in the pressure-sensitive adhesive sheet.

[0011]

To achieve the above object, the present invention comprises I) a support, and II) adhesive elastic microspheres formed on the support and an adhesive polymer. In the pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer comprising: a) the pressure-sensitive adhesive layer has a convex pressure-sensitive adhesive portion containing a cluster formed by at least two elastic microspheres and the pressure-sensitive adhesive polymer. And b) to provide a pressure-sensitive adhesive sheet having an area contact rate of 20 to 90% between the pressure-sensitive adhesive layer and the plate surface when the pressure-sensitive adhesive sheet is attached to a flat glass plate surface at a pressure of 1 kg / cm and measured. .

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In the pressure-sensitive adhesive sheet of the present invention, since the convex pressure-sensitive adhesive portion includes clusters of elastic microspheres, the conformability to the uneven surface of the adherend during adhesion is improved, and the mortar and concrete -Sufficient adhesive force can be obtained even on an adherend having a rough surface such as G. In this specification,
"A cluster of elastic microspheres" means that two or more elastic microspheres are dispersed as an aggregated mass in a matrix containing an adhesive polymer, and have irregular shapes and irregular arrangements. It is defined as an aggregate of elastic microspheres forming a convex portion (convex adhesive portion). That is, the adhesive layer comprises a large number of “island” portions (discontinuous phase) containing clusters and an adhesive polymer and a relatively flat “sea” portion (continuous) containing an adhesive polymer without clusters. Phase) and.

A schematic view of an adhesive sheet containing such a cluster is shown in FIG. This adhesive sheet 1 has a discontinuous convex adhesive portion 3 including a cluster of elastic microspheres 2.

Such a cluster is composed of an aggregate of elastic microspheres arranged in a two-dimensional plane, an aggregate of three-dimensional three-dimensional microspheres, or a hybrid of both. In addition, such a cluster usually causes a shift between the aggregated elastic microspheres during the operation of attaching the pressure-sensitive adhesive sheet to the adherend,
The convex portion is deformed into a shape suitable for bonding to the uneven surface of the adherend. However, this deformation is such that it can be held by forming a passage formed between the uneven surface and the adhesive layer and communicating with the outside air. The degree of such deformation can be controlled by making the elastic microspheres sticky and by containing the elastic microspheres and the adhesive polymer in a predetermined ratio.

The irregular shape of the convex adhesive portion acts to improve the adhesiveness to the adherend having irregular irregularities. The irregular shape of such a convex adhesive part is
Derived from clusters of elastic microspheres of irregular shape and arrangement. The clusters of elastic microspheres can be easily formed, for example, by applying a pressure-sensitive adhesive coating on the surface of the support having a wettability index within a predetermined range to form a pressure-sensitive adhesive layer. Also, controlling the viscosity of the paint within a predetermined range facilitates cluster formation.

When the pressure-sensitive adhesive sheet according to the present invention is attached to the surface of an object, the above-mentioned "sea-island structure" (continuous / discontinuous phase structure) is formed by the surface of the object and the pressure-sensitive adhesive layer and has a passage communicating with the outside air. It is possible to prevent the swelling of the adhesive layer due to steam containing water that has leached from the adherend side. In order to effectively form such a passage, the area contact ratio between the pressure-sensitive adhesive layer and its flat surface measured by attaching a pressure-sensitive adhesive sheet to a flat glass plate surface (defining the degree of contact between the two is defined. Value, which will be defined later) within a predetermined range. Such control of the area contact ratio is performed, for example, by setting the ratio of the elastic microspheres and the adhesive polymer to a predetermined range and using elastic microspheres having a predetermined average diameter to set the coating weight of the adhesive layer to an appropriate range. By doing so, it can be easily performed.

1. Elastic Microspheres In the present specification, “adhesive elastic microspheres” (hereinafter also referred to as “microspheres”) have adhesiveness on at least the surface thereof and exhibit rubber elasticity as a whole of the microspheres. Defined as a material. The fact that the microspheres have rubber elasticity means that
It is necessary to form the above-mentioned passages that enhance the adhesion to the uneven surface and prevent the adhesive layer from swelling. Further, being microspheres facilitates and ensures the formation of a cluster structure and also acts to enhance the adhesive force to the uneven surface.

The term "microsphere" as used herein usually means a volume average diameter of less than 500 μm, and usually 10 to 300 μm.
However, it is preferably in the range of 50 to 250 μm. When the volume average diameter is in the range of 50 to 250 μm, the uneven surface is followed particularly well, the apparent area contact ratio is increased, and as a result, sufficient adhesive force can be obtained. The volume average diameter is a value determined by measuring 1000 microspheres using an image processing device using an optical microscope and applying the measured value to the following formula (1).

[0019]

[Number 1] volume average diameter (μm) = Σ in ^{_{(d i 4 · n i)}} / Σ (d i 3 · n i) expression, d _i is the i th size of the diameter of the microspheres ([mu] m )
In and, n _i is the number of microspheres having a diameter d _i.

The microspheres may be solid spheres or hollow spheres having one or more pores. As the material for the microspheres, polyacrylate is preferable because it is easily available and the rubber elasticity and adhesiveness can be easily controlled. The compression modulus of the microspheres is preferably in the range of 1 × 10 ⁴ to 1 × 10 ⁶ dyne / cm ² . When the compression modulus is in this range, the microspheres themselves and / or the clusters are effectively deformed, and the adhesive layer is effectively adhered to the uneven surface.

The compressive modulus is RS from Rheometrics
AII is the compression modulus measured at 20 ° C. using a viscoelastic spectrometer. That is, while giving a compressive strain at 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 elastic modulus was measured.
The measured value at is defined as the compression modulus.

2. Method for Producing Elastic Microspheres The above-described microspheres can be produced by a known synthesis method such as suspension polymerization, emulsion polymerization, or seed polymerization. For example, a method for producing polyacrylate microspheres by suspension polymerization will be briefly described below. Deionized water, an acrylic monomer component, a radical polymerization initiator, and other desired additives are placed in a reactor equipped with a mechanical stirrer. Usually, the reactor is purged with an inert gas and stirred at a predetermined temperature. To start the polymerization reaction of the monomer component. The stirring speed is usually 10 to 700 RPM, and the reaction temperature is
Usually, it is 30 to 120 ° C. The reaction time is usually from several hours to several tens of hours.

As the acrylic monomer component, alkyl acrylates (eg, isooctyl acrylate,
A mixture of 2-ethylhexyl acrylate, isononyl acrylate, etc.) and an acrylic unsaturated acid (for example, acrylic acid, methacrylic acid, itaconic acid, maleic acid, etc.) can be used. The (weight) ratio of alkyl acrylate to acrylic unsaturated acid contained in this mixture is preferably in the range of 99: 1 to 90:10. If the amount of the alkyl acrylate is too small, the tackiness will be low, and if it is too large, the rubber elasticity will decrease, and in both cases, the adhesive strength to the uneven surface tends to decrease. 1,4-dibutyl-
It is also possible to add a crosslinking component composed of a bifunctional acrylate such as 2-diacrylate divinylbenzene to the above mixture to crosslink the polyacrylate. A method for producing such polyacrylate microspheres is disclosed in, for example, US Pat. No. 4,994,322. The synthesized microspheres are usually used after being filtered out, but the aqueous dispersion containing the microspheres after the reaction is used as it is,
It is also possible to prepare a pressure-sensitive adhesive coating by adding an adhesive polymer to the aqueous dispersion.

3. Tacky Polymer In the present specification, the “tacky polymer” means a polymer that exhibits tackiness at room temperature and can be used as a pressure-sensitive adhesive. Examples of such polymers include polyacrylate,
Polyurethane, polyolefin, polyester, etc. can be used. In addition, a tackifier can be used together with a tacky polymer, similarly to a conventionally known pressure-sensitive adhesive.
The molecular weight of the pressure-sensitive adhesive polymer may be within the range where a predetermined pressure-sensitive adhesiveness is exhibited, and is usually a weight average molecular weight of 10,0.
The range is from 00 to 100,000.

4. Adhesive Layer The “adhesive layer” in the present invention is a layer composed of an adhesive component containing microspheres and an adhesive polymer and having a large number of irregular-shaped convex adhesive portions. The irregular-shaped convex adhesive portion enables the development of good adhesiveness to the uneven surface and the formation of the passage communicating with the outside air that effectively prevents the adhesive layer from swelling. The mixing ratio of the microspheres and the adhesive polymer is such that the content of the microspheres relative to 100 parts by weight of the adhesive polymer is
20 to 500 parts by weight, particularly preferably 100 to 4 parts by weight
It is in the range of 00 parts by weight. If it is less than 20 parts by weight, it is difficult to form a cluster of effective size (details will be described later). On the contrary, if it exceeds 500 parts by weight, a passage communicating with the outside air between the uneven surface and the adhesive layer is formed. It may be difficult to form, and it may be difficult to prevent the pressure-sensitive adhesive layer from swelling due to moisture or the like.

[5] Support The support may be any of those used as a support for conventional pressure-sensitive adhesive sheets, and for example, paper, metal film, plastic film and the like can be used. As the plastic, synthetic polymers such as polyvinyl chloride, polyester, polyurethane and polyacrylate can be used. The thickness of the film is usually 10 to 1500 μm. The surface of the support on which the pressure-sensitive adhesive layer is formed may be subjected to a surface treatment for the purpose of increasing the adhesive strength of the pressure-sensitive adhesive layer or for controlling the wetting index as described later.

6. Clusters of Elastic Microspheres “Cluster” as used herein is defined as above. Usually, this cluster consists of at least two microspheres, but a cluster of a size effective for particularly favorable adhesion performance consists of 10 to 200 microspheres. Also,
In the entire adhesive layer, such effective size clusters are
It is preferable that the total amount of the cluster is 80% or more. The formation of clusters of microspheres in the adhesive layer and the confirmation of the shape, size, etc. are carried out by observation using reflected light from an optical microscope, and usually at a magnification of 10 to 100 times.

One suitable means for forming clusters is to increase the wetting index of the coated surface of the support by 35 to 70 dyne.
It is a method in which the pressure-sensitive adhesive layer is adjusted to a range of / cm ² , a pressure-sensitive adhesive coating is applied to the surface to be coated, and the coating is dried to form a pressure-sensitive adhesive layer. If the wetting index is too low, the adhesive layer tends to be unevenly coated and the adhesive strength on the rough surface tends to be lowered. Conversely, a wetting index that is too high can make effective cluster formation difficult. From this point of view, a particularly preferable wetting index is 40 to 60 dyne / cm ² .

The wetting index of the support can be controlled by surface-treating the support by corona treatment, plasma treatment, chemical treatment or the like. In the case of a plastic film, it can be controlled by the type and amount of additives such as a plasticizer contained in the film. Corona discharge treatment is suitable as a method for controlling the wetting index. This is because it is possible to avoid mixing chemicals in the adhesive layer as compared with chemical treatment. When performing corona discharge treatment, discharge energy is usually 0.1-3k
The range of W and the discharge frequency are in the range of 5,000 to 35,000 Hz. Further, the corona discharge treatment can be performed in air, but can also be performed in an atmosphere of nitrogen gas or the like. For chemical treatment, a solution of acid, alkali, or organic amines, a solution containing trichloroacetic acid or a phenol compound can be used as a chemical, and such a chemical is applied to the surface to be coated, and if necessary, heated and dried. And perform. Here, the "wetting index" means JIS 6768 (1
977) according to the wetting test method, 23 ± 2 ° C.,
It is a value measured in a temperature and humidity environment of 50 ± 5% RH.

Controlling the viscosity of the pressure-sensitive adhesive coating is also useful for facilitating cluster formation, and the viscosity of the pressure-sensitive adhesive coating is preferably in the range of 100 to 6000 cps. 100 cps
If it is lower than 6000 cps, it tends to be difficult to form an adhesive layer with a sufficient coating weight. On the other hand, if it is higher than 6000 cps, an adhesive layer having a uniform arrangement of microspheres is likely to be formed.
As a result, effective clusters may not be formed. Further, as described above, the compounding ratio of the adhesive polymer and the microspheres, the adhesiveness of the microspheres, etc. can be factors that control effective cluster formation. Suitable coating weight to form an effective cluster is in the range of 5 to 150 g / m ^2,
Particularly preferably, it is in the range of 50 to 100 g / m ² .

7. Area contact ratio The ratio of the true contact area between the adhesive layer and the adherend to the apparent contact area, that is, the contact area ratio is within an appropriate range, because high adhesion to uneven surfaces and porous surface It is necessary in order to achieve both prevention of swelling of the adhesive layer when it is attached to the adherend. However, it is very difficult to define the degree of contact between the pressure-sensitive adhesive layer and the adherend by measuring the area contact ratio of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to the present invention to the uneven surface. Therefore, the area contact ratio between the pressure-sensitive adhesive layer and the flat surface, which is measured by attaching the pressure-sensitive adhesive sheet to the flat surface of the glass plate, is defined.

Specifically, a flat glass plate surface such as a slide glass and an adhesive layer surface of an adhesive sheet are bonded together, and then reciprocated once with a 2 kg roller to obtain a measurement sample. At the time of pressure bonding, the width of the pressure sensitive adhesive sheet was 2 cm and the rolling direction of the roller was the length direction so that the linear pressure was 1 kg / cm. When the glass plate on the side where the sheet is not attached is illuminated with white light and observed through a polarizing plate, the region where the convex adhesive portion and the glass surface are in contact looks blackish, and the non-contacting region looks whitish. By taking a picture of such an observation state, the area of the contact area and the area of the entire observation field of view (corresponding to the apparent contact area) are measured, and the ratio of the two (area of the contact area / area of the entire observation field of view). ) Is expressed as a percentage to be the "area contact rate". Such an operation can be performed using an ordinary optical microscope equipped with a polaroid camera. In this case, the area of the observation visual field is usually 1 cm ² . The surface roughness Ra of the glass plate used is 0.1 μm or less.

The area contact ratio thus measured is preferably 20 to 90%, more preferably 40 to 80%, and particularly preferably 50 to 70%. Within such a range, it is possible to easily achieve both the adhesiveness to the uneven surface and the effective formation of the passage between the adherend and the adherend, through which steam containing water and the like escape. Such an area contact ratio tends to increase as the size of the microspheres decreases and the coating weight of the adhesive layer increases, and tends to decrease as the content of the microspheres in the adhesive polymer increases. Therefore,
By controlling these parameters within a predetermined range, the area contact ratio can be easily set within the above range.

8. Method for producing pressure-sensitive adhesive sheet The pressure-sensitive adhesive sheet according to the present invention can be produced by a method of forming a pressure-sensitive adhesive layer by applying a pressure-sensitive adhesive paint on one side or both sides of a support and drying the coating. At this time, cluster formation can be effectively performed by using the means as described above.

The pressure-sensitive adhesive coating is usually a pressure-sensitive adhesive prepared by mixing microspheres, a pressure-sensitive polymer, a solvent and, if necessary, various additives in a mixing device such as a homomixer or a planetary mixer to uniformly disperse each material. Prepared as a paint. The coating material thus prepared is applied on a support and dried to form an adhesive layer. As the coating means, known means such as knife coater, roll coater, die coater and bar coater can be used. Also, the drying is usually 60 to 1.
It is carried out at a temperature of 80 ° C. The drying time is usually several tens of seconds to several minutes.

Although water or an organic solvent can be used as the solvent, a water-based pressure-sensitive adhesive coating is suitable for effective cluster formation. The drying temperature in this case is usually 100 ° C.
That is all. Further, a co-solvent partially compatible with water can also be added. Useful cosolvents include, for example, 3-
Examples thereof include alkylene glycol monoalkyl ether esters such as methyl-3-methoxybutyl acetate. Conventionally known additives can be used as long as the effects of the present invention are not impaired. For example, a viscosity adjusting agent, a defoaming agent, a leveling agent, an ultraviolet absorber, an antioxidant, a pigment and the like. Further, after forming the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer can be usually covered with a silicone-treated liner for protection thereof.

9. Adhesive Sheet The adhesive sheet according to the present invention can be used as a decorative sheet by being attached to a wall surface, floor surface, ceiling surface, etc. of a building or the like. In particular, it is useful when the surface is covered with mortar, concrete, wallpaper, etc., the degree of unevenness is large, and the shape and size of the unevenness are irregular.

On the adhesive surface of the adhesive layer of the adhesive sheet according to the present invention, a large number of convex adhesive portions containing microsphere clusters are formed. When the adhesive sheet is attached, the adherend surface and the adhesive surface are in point contact with each other. Then, a continuous passage is formed. When it is attached to a porous adherend that has a water-absorbing property because it has such a structure, it is possible to easily remove the steam containing water that has entered the adherend from the outside into the atmosphere through this passage. Therefore, it is possible to prevent the swelling of the adhesive layer due to such moisture. The swelling of the adhesive layer impairs the appearance of the sheet after pasting when it reaches the support and also causes the sheet to peel off from the adherend. The pressure-sensitive adhesive sheet of the present invention is particularly useful when used for an adherend that faces the outdoors, such as an outer wall made of. The performance of the pressure-sensitive adhesive sheet according to the present invention is such that the adhesive force to the mortar surface measured as described below is higher than that of the conventional product (for example, 2 kg / 2.5c).
swelling of the adhesive layer due to leaching of steam containing water. The present invention will be specifically described by the following examples, including such effects.

[0039]

EXAMPLES In Examples 1-14 and Comparative Examples 3-4, the following elastic microspheres, tacky polymers, and support films were used: Elastic Microspheres Elastic microspheres were waterborne as described above. Was produced by suspension polymerization. The monomer composition used is IOA / AA
= 96/4 weight (IOA: isooctyl acrylate, AA: acrylic acid). The volume average diameter in each example is shown in Table 1. The compression modulus was set to be 7 × 10 ⁵ dyne / cm ² for microspheres of all diameters. The compression modulus was determined by removing the solvent from the suspension containing elastic microspheres, forming a cylinder for measurement with a diameter of 5 mm and a length of 7 mm to prepare a measurement sample, and mounting the sample on a parallel plate jig. It measured on the measurement conditions of.

Adhesive Polymer As an adhesive polymer, a water dispersion adhesive (E-
1000) was used. The monomer composition was butyl acrylate / acrylic acid = 94/6 weight.

Support Film The support has a polyester carrier of 50 μm (thickness).
It was a 0 μm (thickness) PVC film. This support is
It was prepared from a vinyl chloride homopolymer solution by a casting method. Further, the wettability index of the support was controlled to the value shown in Table 1 by subjecting the coated surface to corona discharge treatment.

Preparation of Sample An adhesive paint prepared by mixing 100 parts by weight of an adhesive polymer with elastic microspheres in an amount shown in Table 1 and stirring with a homomixer was dried on a support film. The coating weight was directly applied with a knife coater so that the coating weight was obtained as shown in Table 1. After drying at 105 ° C. for 5 minutes, a silicone liner (PK530BH, made by Tokushu Paper Co., Ltd.) was laminated to produce a liner-attached pressure-sensitive adhesive sheet.

In Comparative Examples 1 and 2, existing products were used. That is, in Comparative Example 1, Scotchcal Film UPF-1 manufactured by 3M was used, and in Comparative Example 2, Pharaon sheet manufactured by Pharaon was used. Both are commercially available marking films for concrete.

The following properties of each pressure-sensitive adhesive sheet were measured. Area contact rate 76 mm (length) x 26 mm (width) x 1 mm (thickness) slide glass (Matsunami Glass Industry Co., Ltd., MICRO SLI)
Liner on the flat surface of DE GLASS white green No. 1)
The sample was prepared by sticking together the adhesive surface of an adhesive sheet having a width of 2 cm and a length of 5 cm, which was peeled off, and making a reciprocal pressure contact with the roller of 2 kg having a width of about 4.5 cm in the longitudinal direction. Was measured according to. Ra of the flat surface of this slide glass
Was about 0.001 μm.

Bubble Ejection Performance A 10 cm × 10 cm pressure-sensitive adhesive sheet from which the liner has been peeled off is placed on a smooth acrylic plate and pressure-bonded with a squeegee toward the center of the film so that bubbles collect. A 2 kg roller is rotated several times over the bubbles thus created, and the state of escape of the bubbles is observed. Those in which air bubbles were completely removed were evaluated as "good", and those in which some air bubbles remained were evaluated as "bad".

A pressure-sensitive adhesive sheet having a peeling adhesive force of 15 cm × 2.5 cm is placed at 20 ° C. × 65% RH.
NT degreased with isopropyl alcohol under
Rough surface of mortar plate made of P (Ra of the adhered surface is 20 to 100 μm
m range) according to JIS Z 0237 (1980) and left under the same temperature and humidity conditions for 48 hours and then 180 °
The peeling force was measured at a peeling speed of 30 cm / min.

Presence or absence of swelling An adhesive sheet of 15 cm × 2.5 cm is attached to the rough surface of the NTP mortar plate using a rivet brush, and the temperature is 40 ° C.
Immerse in warm water for 1 week. At this time, if the film did not swell, it was evaluated as “none”, if there was relatively slight swelling but did not peel off from the adherend, it was evaluated as “mild”, and if swelling and peeling occurred, it was evaluated as “present”.

Solution Viscosity 23
Spindle No. 4, rotation speed 60rp using B type viscometer at ℃
It was measured under the condition of m. Table 1 shows the results.

[0049]

[Table 1]

[Brief description of the drawings]

FIG. 1 is a schematic view of an adhesive sheet containing microsphere clusters of the present invention.

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Claims (5)

[Claims] 1. A pressure-sensitive adhesive sheet comprising: I) a support; and II) a pressure-sensitive adhesive layer which is formed on the support and contains adhesive elastic microspheres and a pressure-sensitive polymer. The pressure-sensitive adhesive layer has a convex pressure-sensitive adhesive portion containing a cluster formed by gathering at least two elastic microspheres and the pressure-sensitive adhesive polymer, and b) the pressure-sensitive adhesive sheet is flattened at a pressure of 1 kg / cm. A pressure-sensitive adhesive sheet having an area contact ratio of 20 to 90% between the pressure-sensitive adhesive layer and the surface of the plate when measured by being attached to the surface of the glass plate. 2. The wetting index of the surface of the support is 35 to 35.
70 dyne / cm ² , and the pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer formed by applying a pressure-sensitive adhesive paint containing the elastic microspheres, the pressure-sensitive adhesive polymer and a solvent on the surface of the support. The adhesive sheet described. 3. A step of preparing an adhesive coating composition containing i) 100 parts by weight of an adhesive polymer and 20 to 500 parts by weight of elastic microspheres, and ii) a coated surface having a wetting index of 35 to 70 dyne / cm ^2. The coating material is applied to the surface to be coated of the support having the above to form a cluster of elastic microspheres, and an adhesive layer having an irregular convex adhesive portion containing the cluster and the adhesive polymer is formed. The method for producing a pressure-sensitive adhesive sheet according to claim 1, comprising a step. 4. The viscosity of the paint is 100 to 6000 cp.
The method for producing an adhesive sheet according to claim 3, wherein the adhesive sheet is s. 5. An object having a rough surface containing mortar or concrete, and the pressure-sensitive adhesive sheet according to claim 1 attached to the surface of the object, the surface being formed of the pressure-sensitive adhesive layer, and communicating with the outside air. Adhesive sheet pasting structure with a passage.