JP5598385B2 - Re-peelable pressure-sensitive adhesive sheet and method for producing the same - Google Patents

Description

  The present invention relates to a releasable pressure-sensitive adhesive sheet and a method for producing the same.

The re-peelable pressure-sensitive adhesive sheet is a pressure-sensitive adhesive sheet having a function that can be easily peeled off from an adherend after a certain period of time after being applied. The re-peelable pressure-sensitive adhesive sheet is used, for example, as a concealment label on a piece of personal information written on a postcard at the time of mailing, and used by a recipient to peel off the personal information and read the personal information. It is also used as a management label between product manufacturing processes and as a logistics management label in the distribution process of products, for printing necessary information and removing the label when the purpose of information transmission is no longer needed. ing.
The required quality for these releasable pressure-sensitive adhesive sheets is two points: good adhesion to the article that is the adherend, and easy and clean removal without tearing the adhesive residue or base material when peeled off. .

However, good adhesiveness and good removability are contradictory properties in terms of the adhesive strength of the adhesive sheet. That is, high adhesive strength is required for good adhesion, and low adhesive strength is required for good removability.
In order to satisfy the contradictory adhesive physical properties, an adhesive coating liquid containing adhesive microspheres is used to form an adhesive layer having an uneven surface, whereby the adhesive layer of the adhesive sheet and the adherend A method has been devised in which the contact area is reduced to reduce the adhesive force and improve the removability (see, for example, Patent Document 1 and Patent Document 2).
In addition, a method has been devised in which adhesive strength is reduced by providing a pattern-like adhesion suppression layer on an adhesive layer that does not contain adhesive microspheres, and re-peelability is improved (for example, Patent Documents). 3 and 4).

JP 2003-25732 A JP 2005-126479 A JP 2006-145974 A JP 2008-65084 A

However, with any of the conventional methods, it is difficult to adjust the delicate adhesive force that achieves both good adhesiveness and good removability, and the production of removable adhesive sheets requires work that depends on intuition and experience. It was necessary. In particular, when used for a concealment label, a high degree of removability is required in order to be able to cope with a high-speed peeling process using an automatic label peeling apparatus. For this reason, it is more difficult to adjust the adhesive strength when used for concealment labels.
The present invention has been made in view of the above circumstances, and is a releasable pressure-sensitive adhesive sheet capable of satisfying both high adhesiveness and high removability capable of handling high-speed peeling processing by an automatic label peeling apparatus, and It is an object to provide a manufacturing method thereof.

In order to achieve the above object, the present invention employs the following configuration.
[1] A base material, an adhesive layer provided on one surface of the base material, and an adhesion suppression layer provided in a pattern on the adhesive layer, wherein the adhesive layer is adhesive becomes fine spheres and tacky microsphere from the adhesive to stick to the substrate, wherein the average particle diameter h ₁ tacky microspheres, the average thickness h ₂ of a layer of the adhesive, the adhesive suppressing layer removable adhesive sheet and the average thickness h _3, characterized in that the following relationship.
h ₁ ≧ h ₂ + h ₃
[2] A step of directly forming an adhesive layer comprising an adhesive microsphere and an adhesive for fixing the adhesive microsphere to the substrate on one surface of the substrate, and a pattern on the adhesive layer. Forming an adhesion suppression layer in the form of an average particle size h ₁ of the adhesive microspheres, an average thickness h ₂ of the adhesive layer, and an average thickness h ₃ of the adhesion suppression layer. A method for producing a releasable pressure-sensitive adhesive sheet, characterized by having the following relationship:
h ₁ ≧ h ₂ + h ₃
[3] The step of forming the pressure-sensitive adhesive layer includes a step of directly applying a pressure-sensitive adhesive coating solution containing a pressure-sensitive microsphere and an adhesive to one surface of the substrate, and the pressure-sensitive adhesive coating solution. The manufacturing method of the releasable adhesive sheet as described in [2] which has a process which dries.
[4] The step of forming the adhesion suppressing layer includes a step of printing on the pressure-sensitive adhesive layer with an ultraviolet curable ink in a pattern, and a step of curing the printed ultraviolet curable ink by ultraviolet irradiation. [2] The method for producing a releasable pressure-sensitive adhesive sheet according to [3].

  According to the releasable pressure-sensitive adhesive sheet and the method for producing the same according to the present invention, it is possible to achieve both good adhesiveness and a high degree of removability that can cope with a high-speed peeling process using an automatic label peeling apparatus.

It is the figure which represented typically the cross section of the releasable adhesive sheet of this invention.

<Removable adhesive sheet>
The releasable pressure-sensitive adhesive sheet of the present invention will be described with reference to FIG. The re-peelable pressure-sensitive adhesive sheet of the present invention comprises a pressure-sensitive adhesive layer 4 in which a pressure-sensitive adhesive microsphere 2 and an adhesive 3 that fixes the pressure-sensitive adhesive microsphere 2 to the substrate 1 are mixed on one surface of the substrate 1. Is provided. Moreover, the adhesion suppression layer 5 is provided on the adhesive layer 4 in a pattern.
The adhesive microsphere 2 is a microsphere that itself has adhesiveness. Further, the adhesion suppression layer 5 is a so-called paste-killing layer having a function of suppressing the adhesive force of the adhesive layer 4.

The average particle diameter h ₁ tacky microspheres 2, an average thickness h ₂ of the layer of adhesive 3, the average thickness h ₃ of the adhesive suppressing layer 5, the relation of the following equation (1).
h ₁ ≧ h ₂ + h ₃ (1)
The average particle diameter h ₁ of the adhesive microsphere 2 is a number average particle diameter. The average particle diameter h ₁ can be obtained from an average value obtained by selecting about 100 adhesive microspheres 2 randomly from an electron micrograph and measuring each particle diameter. In addition, when the adhesive microsphere 2 is not a true sphere, the major axis and the minor axis are obtained, and the average value is used as the particle diameter of the adhesive microsphere 2.
The average thickness h ₂ of the layer of adhesive 2, the layer thickness of the adhesive 3 of about 100 places randomly electron micrograph was measured, can be determined by the average value. Similarly, the average thickness h ₃ of the adhesive suppressing layer 5, the layer thickness of the adhesive suppressing layer 5 of approximately 100 sites randomly electron micrograph was measured, can be determined by the average value.

The inventor of the present application originally thought that if the pressure-sensitive adhesive layer containing the pressure-sensitive microspheres and the pattern-like pressure-sensitive adhesive layer were combined, a fine adjustment of the adhesive strength would be possible. However, for example, when an adhesion suppression layer is provided in a pattern on the pressure-sensitive adhesive layer of Patent Document 2, even if the area where the adhesion suppression layer is provided is extremely small, the adhesive force is extremely reduced, and on the contrary, good adhesion is achieved. Compatibility and removability became difficult.
In order to clarify the cause, the inventor of the present application observed the surface of a test sheet provided with an adhesion suppression layer on an adhesive layer containing adhesive microspheres with an electron microscope. As a result, the region where the adhesion suppression layer is provided is that the adhesion suppression layer covers the entire adhesive layer including the adhesive microspheres, and the region where the adhesion suppression layer is provided is the adhesion suppression layer. It became clear that there was a difference in level compared to the area where no pattern was provided.
That is, it was estimated that the extreme decrease in adhesive strength was due to the following two factors.
1) The adhesive layer in the region where the adhesion suppressing layer is provided is covered including the adhesive microspheres.
2) The adhesion suppression layer is not provided because the total thickness of the adhesive layer and the adhesion suppression layer in the region where the adhesion suppression layer is provided is larger than the thickness of the adhesive layer in the region where the adhesion suppression layer is not provided. The pressure-sensitive adhesive layer in the area is in a floating state from the adherend.

On the other hand, if the relationship of Formula (1) is satisfied, many adhesive microspheres 2 can be exposed on the surface of the adhesive layer 4 even in the region where the adhesion suppression layer 5 is provided. Moreover, the extreme adhesive force fall of the area | region in which the adhesion suppression layer 5 is provided can be suppressed. Further, since no step is generated between the region where the adhesion suppression layer is provided and the region where the adhesion suppression layer is not provided, adhesion between the adhesive layer and the adherend in the region where the adhesion suppression layer is not provided is not hindered. As a result, according to the releasable pressure-sensitive adhesive sheet of the invention, it is possible to finely adjust the adhesive force.
In addition, a part or all of the adhesive microspheres 2 may be fixed to the base material 1 in a state of floating in the middle of the adhesive 3 without directly contacting the base material 1. In that case, if the relationship of Formula (1) is satisfied, more adhesive microspheres 2 can be exposed on the surface of the adhesive layer 4, which is preferable.

The average particle diameter h ₁ tacky microspheres 2, the average difference α between the total thickness h _2, and the average thickness h _3, with respect to the average particle diameter of h _1, preferably from 0 to 0.8 times 0.4 to 0.7 times is more preferable. If the difference α is equal to or greater than the preferable lower limit value, it is easy to prevent the pressure-sensitive adhesive layer 4 in the region where the adhesion suppression layer 5 is not provided from floating from the adherend. If difference (alpha) is below a preferable upper limit, it will be easy to acquire the adhesive force suppression effect of the adhesive layer 4 by the adhesion suppression layer 5 fully.
The ratio of the adhesive microspheres 2 exposed on the surface of the pressure-sensitive adhesive layer 4 is preferably 20 to 80%, more preferably 40 to 60% with respect to the entire adhesive microspheres 2. .
The average particle size h ₁ is preferably 20 to 80 μm, and more preferably 30 to 50 μm. When the average particle diameter h ₁ is equal to or higher than the preferred lower limit, finished roughening of the adhesive layer 4 the surface of the adhesive sheet is improved removability is good, preferably spot gluing emphasis by more than the upper limit It is not too much and can maintain excellent adhesiveness.

The average thickness _{h 2} of the layer of adhesive 3, with respect to the average particle diameter of _{h 1,} preferably from 0.01 to 0.6 times, and more preferably 0.1 to 0.5 times. When the average thickness h ₂ is equal to or more than the preferable lower limit value, the adhesive microspheres 2 can be reliably fixed to the substrate 1 reliably. If less average thickness h ₂ is preferred upper limit, it is easy to secure a sufficient thickness to function adhesive suppressing layer 5.
The average thickness h ₃ of the adhesion suppression layer 5 is preferably 1 to 20 μm, and more preferably 2 to 10 μm. If the average thickness h ₃ is preferably less than the lower limit, it is easy to perform the function of adhesion inhibition. When the average thickness h ₃ or less is preferable upper limit value, easily preventing metastasis to fall off or adherend of the adhesive suppressing layer 5.
In addition, although there is no limitation in particular in the thickness of the base material 1, it can be 20-150 micrometers, for example.

  There is no limitation in particular in the pattern of the area | region which provides the adhesion suppression layer 5, For example, the pattern which consists of a dot, a line, these combinations, etc. is employable. Moreover, there may be a region where the adhesion suppression layer 5 is solid. For example, a portion that becomes a curled edge when the label is peeled off by an automatic peeling device can be a region where the adhesion suppressing layer 5 is solid.

[Base material]
As the substrate 1, a known material can be used as long as it is used as a substrate of a releasable pressure-sensitive adhesive sheet. For example, printing paper such as high-quality paper, art paper, coated paper, cast paper, thermal recording paper, thermal transfer recording paper, electrostatic recording paper, information recording paper such as inkjet recording paper, other kraft paper, impregnated paper, low-size paper And paper base materials such as water-soluble paper, and film base materials such as PET film, PE film, PP film, synthetic paper, and non-woven fabric. Moreover, the base material which laminated | stacked the anchor layer for the purpose of improving the adhesiveness with the adhesive layer 4 can also be used for these base materials.

When the base material 1 is a paper base material, the adhesive 3 can be penetrated into the inside of the surface base material, but in the case of a film base material, it is impossible, so in this case, an anchor layer is laminated. Is preferred.
There is no particular limitation on the anchor layer. For example, kaolin, calcium carbonate, clay, talc, calcined kaolin, delaminated kaolin, titanium dioxide, aluminum hydroxide, silica, white carbon and other inorganic pigments, polystyrene resin fine particles, urea-formalin resin fine particles , Pigments such as organic synthetic pigments such as fine hollow particles and, for example, casein, dextrin, starch, carboxymethylcellulose, methylcellulose, ethylcellulose, hydroxyethylcellulose, polyvinyl alcohol, styrene-butadiene copolymer, methylmethacrylate-butadiene copolymer, A material mainly composed of a natural or synthetic resin binder, such as an ethylene-vinyl chloride copolymer, an ethylene-vinyl acetate copolymer, or an acrylate copolymer, is, for example, 0. It can be provided about to 10 g / ^{m 2.} The blending ratio of the pigment and the binder is a solid content ratio and is preferably adjusted in a range of about 0 to 100: 100.

[Adhesive microspheres]
The adhesive microsphere 2 preferably has a gel fraction of 80 to 95%. Here, the gel fraction means that a predetermined amount W ₁ (about 1 g) of adhesive microspheres is stirred and immersed in THF at room temperature for 1 day, taken out, air-dried for 2 hours, and further dried at 100 ° C. for 1 hour. The mass W ₂ after drying is measured, and is a value obtained as gel fraction = (W ₂ / W ₁ ) × 100 (%). The adhesive microspheres to be measured were prepared by diluting an adhesive coating liquid containing suspension micropolymers of adhesive microspheres or adhesive microspheres described later with deionized water, and manufactured by Toyo Filter Paper Co., Ltd. Qualitative filter paper No. 101 is filtered and separated by 101.
When the gel fraction is less than 80%, the strength of the adhesive microspheres is weak, and when the adhesive sheet is wound and stored, it is flattened by an external pressure, resulting in a decrease in quality and product storage stability. On the other hand, if it exceeds 95%, the strength of the adhesive microspheres is too strong, and the adhesion to the adherend at the time of sticking the adhesive label becomes poor.

The material of the adhesive microsphere 2 is not particularly limited as long as the material itself is an adhesive microsphere having adhesiveness, but is made of an acrylic copolymer due to the excellent physical properties of the obtained releasable adhesive sheet. It is preferable.
Examples of the adhesive microsphere made of such an acrylic copolymer include adhesive fine particles obtained by a method according to Japanese Patent Application Laid-Open No. 2000-281988. That is,
(A) 60-100% by mass of an acrylate monomer represented by the general formula CH ₂ = CHCOOR ¹ (wherein R ¹ represents a linear or branched alkyl group having 4 to 10 carbon atoms),
(B) 0 to 10% by mass of an unsaturated monomer having a carboxy group,
(C) Acrylic copolymer fine particles obtained by copolymerizing 0 to 40% by mass of other unsaturated monomers copolymerizable with the monomers (a) and (b) are preferred. .

Monomer (a) is an acrylic acid ester of the formula CH ₂ = CHCOOR ^1, the R ¹ represents a linear or branched alkyl group having 4 to 10 carbon atoms, such group R ¹ Examples include n-butyl group, i-butyl group, n-hexyl group, 2-ethylhexyl group, n-octyl group, i-octyl group, n-nonyl group, i-nonyl group, n-decyl group and the like. Can be mentioned.
The usage-amount of the acrylic acid ester which is a monomer (a) is 60-100 mass% in total 100 mass% of (a)-(c), for example, Preferably it is 70-100 mass%. By using the acrylate monomer (a) in the above lower limit amount or more, a good balance between excellent adhesive force and excellent tackiness and excellent cohesive force is achieved.

Examples of the monomer (b) containing a carboxy group include an α, β-unsaturated monomer or a dicarboxylic acid monomer, and an α, β-unsaturated monomer having 3 to 5 carbon atoms. Alternatively, it is preferable to use a di-carboxylic acid monomer.
The amount of the monomer (b) used is preferably, for example, 0 to 10% by mass and more preferably 0.5 to 5% by mass in 100% by mass of (a) to (c). preferable. When the amount of the monomer (b) used is not less than the above lower limit amount, the resulting adhesive microsphere dispersion has excellent mechanical stability and cohesive force. Therefore, it is preferable to appropriately select and use the amount within the above range. Further, taking into consideration the balance of tackiness and cohesive force, stability of adhesive strength over time, heat and humidity resistance, etc., if necessary, a suitable range amount can be experimentally selected within the above range in advance.

As the monomer (c), for example, an alkyl group having 1 to 3 carbon atoms (meth) acrylic acid ester, maleic acid ester or fumaric acid ester, saturated fatty acid vinyl ester, amide group or substituted amide group, An unsaturated monomer containing at least one functional group such as amino group or substituted amino group, hydroxyl group, epoxy group, mercapto group, radical polymerizable unsaturated group (hereinafter referred to as functional monomer) Functional monomers other than the monomer (b) can be used as necessary.
The amount of the monomer (c) used is preferably, for example, 0 to 40% by mass, and more preferably 0 to 25% by mass in the total 100% by mass of (a) to (c). The amount of the monomer (c) used can vary depending on the type of the monomer, so the amount used can not be determined uniquely. However, the balance between adhesion and tack and the balance between these and cohesion Since it helps to adjust as desired, it can be appropriately selected in the range amount so as to meet such purpose.
If the amount of the monomer (c) used exceeds the upper limit of the range amount and is too large, the tackiness tends to be too small.

Adhesive microspheres made of an acrylic copolymer are obtained by subjecting an acrylic monomer mixture to aqueous suspension polymerization in an aqueous medium in the presence of a surfactant and a polymerization initiator, and if necessary, a suspension stabilizer. Convenient to manufacture. As a method, a known suspension polymerization method is used. For example, a monomer mixture in which a polymerization initiator is dissolved is fixed in an aqueous medium in the presence of a surfactant and, if necessary, a suspension stabilizer. After stirring for a period of time to obtain an oil droplet emulsion having a desired particle size range, the temperature can be raised at a constant stirring speed to initiate the polymerization reaction.
Note that “in an aqueous medium” means in water or an aqueous solution of a water-soluble organic solvent. Examples of such water-soluble organic solvents include water-soluble alcohols, water-soluble ketones, and water-soluble ethers.

[adhesive]
The adhesive 3 includes at least a binder component. As a component preferably contained other than the binder component, a tackifier and a crosslinking agent are exemplified. In addition, other auxiliary agents can be added as necessary. Examples of other auxiliaries include thickeners, pH adjusters, antifoaming agents, antiseptic / antifungal agents, pigments, inorganic fillers, stabilizers, wetting agents, wetting agents and the like.

Binder components include synthetic rubbers such as styrene-butadiene latex and those based on synthetic resins such as rubber, acrylic, SBR, and silicone based on natural rubber, and water-soluble such as polyvinyl alcohol (PVA). A functional polymer. There are an emulsion type, a solvent type, a solventless type and the like, and any type may be used, but among these, an aqueous emulsion type acrylic pressure-sensitive adhesive is preferable from the viewpoint of adhesiveness, durability and cost.
The glass transition temperature (hereinafter referred to as Tg) of the binder component is preferably −30 ° C. to −10 ° C. from the viewpoint of adhesiveness. By making Tg −30 ° C. or higher, the generation of adhesive residue can be reduced, and by setting it to −10 ° C. or lower, the flexibility of the film after film formation can be maintained. High adhesion can be obtained.

The tackifier is used for the purpose of improving the initial adhesiveness. Examples of the tackifier include petroleum resins, natural resins, and derivatives thereof. The petroleum resin, natural resin or derivatives thereof are, for example, terpene resins such as polyterpene resins and modified terpenes; for example, petroleum resins such as aliphatic hydrocarbon resins, cyclopentadiene resins and aromatic petroleum resins. Resins; For example, rosin resins such as rosin, rosin ester, hydrogenated rosin ester; and other examples include phenol resin, styrene resin, xylene resin, and the like. In particular, it is preferable to use petroleum resin, rosin resin or terpene resin.
The softening point of the tackifier is preferably 70 to 180 ° C, more preferably 100 to 160 ° C, and particularly preferably 120 to 150 ° C. The weight average molecular weight (Mw) is preferably 5000 or less, particularly 2000 to 4000.
It is desirable that the tackifier is stably dispersed as a dispersion in an aqueous medium, and the volume average particle diameter of the dispersed particles is preferably 0.4 μm or less, and 0.05 to 0.35 μm. It is particularly preferred.
It is preferable that the ratio of the tackifier contained in the adhesive 3 is 0.1 to 20 parts by mass with respect to 100 parts by mass of the binder component.

Examples of the crosslinking agent include a crosslinking agent having a carbodiimide group, an oxazoline-based crosslinking agent, an epoxy-based crosslinking agent, a hydrazine-based crosslinking agent, and an isocyanate-based crosslinking agent, and a crosslinking agent having a carbodiimide group is preferable. Here, the carbodiimide group refers to a group (NH = C = N-, -N = C = N-) in which one or two hydrogens are extracted from carbodiimide (NH = C = NH). Since carbodiimide has a tautomeric relationship with cyanamide (NCNH ₂ ), a cyanamide group (NCNH—) is also included in the carbodiimide group.
Specific examples of the crosslinking agent having such a carbodiimide group include dicyclohexylmethane carbodiimide, dicyclohexylcarbodiimide, tetramethylxylylene carbodiimide, urea-modified carbodiimide, and the like.
The ratio of the crosslinking agent contained in the adhesive 3 is based on 100 parts by mass of the binder component.
It is preferable that it is 0.05-10 mass parts.

The ratio of the adhesive microspheres 2 to the adhesive 3 is preferably 9.5: 0.5 to 4: 6, and more preferably 9: 1 to 6: 4, in terms of dry mass.
It is preferable that the adhesive microspheres 2 are contained in an amount equal to or more than the lower limit of the preferable ratio because sufficient unevenness can be easily formed, and as a result, excellent removability can be exhibited.
If the adhesive is included in the lower limit of the preferred ratio, the adhesive microspheres 2 can be sufficiently fixed to the substrate 1.

[Adhesion suppression layer]
The adhesion suppression layer 5 can be formed of a printing ink such as an ultraviolet curable ink or a solvent ink, or an overprint varnish. Among these, ultraviolet curable ink is preferable because it hardly affects the pressure-sensitive adhesive layer 4.
The adhesion suppression layer 5 preferably contains a release agent. Examples of the release agent that can be contained in the ultraviolet curable ink include silicone compounds, alkyl pendant polymers, and condensed waxes. Of these, silicone compounds are preferred, and ultraviolet curable silicone compounds are particularly preferred.
As the adhesion suppression layer 5 of the present invention, an ultraviolet curable ink containing an ultraviolet curable silicone compound is particularly preferable.
The adhesion suppression layer 5 may be a colored layer containing a pigment or a dye. In this case, the pattern of the adhesion suppression layer 5 becomes camouflage, and the concealability in the case of using a removable adhesive sheet as a concealment label can be improved. However, when a pigment is included, it is preferable to use a fine pigment so that unevenness does not occur on the surface of the adhesion suppression layer 5.

<Method for producing releasable adhesive sheet>
The re-peelable pressure-sensitive adhesive sheet of the present invention comprises a step of forming a pressure-sensitive adhesive layer comprising a pressure-sensitive adhesive microsphere and an adhesive for fixing the pressure-sensitive adhesive microsphere to the substrate (pressure-sensitive adhesive layer) on one surface of the substrate. Forming step) and a step of forming an adhesion suppression layer in a pattern on the pressure-sensitive adhesive layer (adhesion suppression layer forming step).

[Adhesive layer forming step]
The pressure-sensitive adhesive layer forming step is preferably performed by a so-called direct coating method in which the pressure-sensitive adhesive layer 4 is directly formed on the substrate 1. By using the direct coating method, the adhesiveness of the pressure-sensitive adhesive layer 4 to the substrate 1 can be easily increased. Further, the relationship between the average particle diameter h ₁ of the adhesive microspheres ₂ , the average thickness h ₂ of the layer of the adhesive _3, and the average thickness h ₃ of the adhesion suppression layer 5 is expressed by the following equation (1). Easy to meet.
h ₁ ≧ h ₂ + h ₃ (1)
Specifically, a step of directly applying a pressure-sensitive adhesive coating liquid containing the pressure-sensitive microspheres 2 and the adhesive 3 to the base material 1 on one surface of the base material 1, and the pressure-sensitive adhesive coating applied It is preferable to have a step of drying the liquid.

The pressure-sensitive adhesive coating liquid preferably has a form in which the pressure-sensitive microspheres 2 are dispersed in an emulsion in which the adhesive 3 is dispersed in an aqueous solvent or an aqueous solution in which the adhesive 3 is dissolved in an aqueous solvent.
The pressure-sensitive adhesive coating liquid can be applied by a normal coating machine such as a knife coater, a roll coater, a comma coater, a bar coater, a gravure coater, a lip coater, a die coater, and a screen printing machine.

Sticky fine spheres 2 and the ratio of the adhesive 3, by adjusting the dry coating amount of the adhesive coating solution, it is possible to adjust the average thickness h ₂ of the layer of adhesive 3. For example, when the ratio of the adhesive microspheres 2 to the adhesive 3 is 8: 2 in terms of dry mass, the layer of the adhesive 3 is assumed to have a dry coating amount of 5 to 20 g / m ^{2 of} the adhesive coating liquid. The average thickness h2 can be adjusted to ₁ to 4 μm.
Dry coating amount of the adhesive coating solution is preferably set to 5 to 20 g / ^{m 2,} and more preferably to 6 to 15 g / ^{m 2.}

  When using a so-called transfer method in which a pressure-sensitive adhesive is applied to a release sheet and the pressure-sensitive adhesive layer 4 is transferred to the base material 1 by pasting the pressure-sensitive adhesive layer onto the base material 1, the release sheet and the base material 1 are Gap calendar using a nip roll having a pressure of 98 to 980 N / cm and / or a gap between the two rolls of 20 to 80% of the total thickness of the release sheet on which the pressure-sensitive adhesive layer 4 is formed and the substrate 1 It is preferable to transfer the pressure-sensitive adhesive layer 4 to the substrate 1 by laminating them with each other.

The linear pressure when using the nip roll is more preferably 196 to 686 N / cm. By making the linear pressure more than the preferable lower limit value, the adhesiveness of the pressure-sensitive adhesive layer 4 to the substrate 1 becomes good, and the average particle diameter h ₁ of the pressure-sensitive microspheres 2 and the average thickness of the layer of the adhesive 3 the difference between the h ₂ is likely to increase. On the other hand, when the linear pressure exceeds a preferable upper limit value, the adhesive microspheres 2 are flattened by plastic deformation, so that the average particle diameter h ₁ of the adhesive microspheres ₂ and the average thickness h ₂ of the layer of the adhesive 3 are The difference may be smaller.
The temperature of the roll at the time of nip can be suitably adjusted within the range of about 10-100 degreeC.

More preferably, the gap between the rolls when using the gap-type calender is 20 to 50% of the total thickness of the release sheet on which the pressure-sensitive adhesive layer 4 is formed and the substrate 1. By setting the gap to a preferable upper limit value or less, the adhesiveness of the pressure-sensitive adhesive layer 4 to the substrate 1 is improved, and the average particle diameter h ₁ of the pressure-sensitive microspheres 2 and the average thickness h of the layer of the adhesive 3 _It becomes easy to increase the difference from ₂ . On the other hand, if the gap is less than a preferred lower limit, adhesion fine spheres -2 to flattened by plastic deformation, the adhesive microspheres 2 average particle diameter h ₁ and the average thickness h ₂ of the layer of adhesive 3 The difference may be smaller.
When the nip roll and the gap type calender are used in combination, it is preferable that the linear pressure of the nip roll is set to a relatively low value within the preferable linear pressure range.

[Adhesion suppression layer forming step]
The adhesion suppression layer forming step is a step of forming the adhesion suppression layer 5 in a pattern on the pressure-sensitive adhesive layer 4. The adhesion suppression layer forming step preferably includes a step of printing on the pressure-sensitive adhesive layer 4 with an ultraviolet curable ink in a pattern and a step of curing the printed ultraviolet curable ink by ultraviolet irradiation. The printing is preferably letterpress printing. By making the printing plate into a relief plate, the adhesion between the adhesion suppressing layer 5 and the adhesive 3 layer can be enhanced.
By adjusting the dry coating amount of the ultraviolet curable ink, it is possible to adjust the average thickness h ₃ of the adhesive suppressing layer 5. For example, when the dry coating amount of the ultraviolet curable ink is 1 to 20 g / m ² , the average thickness h ₃ of the adhesion suppression layer 5 can be adjusted to 1 to 20 μm.

  The re-peelable pressure-sensitive adhesive sheet of the present invention can be used, for example, as a concealment label on personal information written on a postcard at the time of mailing, and for a recipient to peel it off and read the personal information. Also, it can be used as a management label between product manufacturing processes and a distribution management label in the product distribution process, for printing necessary information and removing the label when the purpose of information transmission becomes unnecessary .

DESCRIPTION OF SYMBOLS 1 ... Base material, 2 ... Adhesive microsphere, 3 ... Adhesive, 4 ... Adhesive layer, 5 ... Adhesion suppression layer

Claims (4)

A base material, an adhesive layer provided on one surface of the base material, and an adhesion suppression layer provided in a pattern on the adhesive layer,
The pressure-sensitive adhesive layer is composed of an adhesive microsphere and an adhesive that fixes the adhesive microsphere to the substrate,
The removability characterized in that the average particle diameter h ₁ of the adhesive microspheres, the average thickness h ₂ of the adhesive layer, and the average thickness h ₃ of the adhesion suppression layer are in the following relationship: Adhesive sheet.
h ₁ ≧ h ₂ + h ₃ Directly forming a pressure-sensitive adhesive layer composed of an adhesive microsphere and an adhesive for fixing the adhesive microsphere to the base on one surface of the substrate;
A step of forming an adhesion suppression layer in a pattern on the pressure-sensitive adhesive layer,
The average particle diameter h ₁ of the adhesive microspheres, the average thickness h ₂ of the adhesive layer, and the average thickness h ₃ of the adhesion suppressing layer have the following relationship: A method for producing a releasable pressure-sensitive adhesive sheet.
h ₁ ≧ h ₂ + h ₃   The step of forming the pressure-sensitive adhesive layer includes a step of directly applying a pressure-sensitive adhesive coating liquid containing pressure-sensitive microspheres and an adhesive to one surface of the substrate, and drying the pressure-sensitive adhesive coating liquid. The manufacturing method of the releasable adhesive sheet of Claim 2 which has a process. The step of forming the adhesion suppression layer is a step of printing on the pressure-sensitive adhesive layer with ultraviolet curable ink in a pattern,
The manufacturing method of the releasable adhesive sheet of Claim 2 or 3 which has the process of hardening the said printed ultraviolet curable ink by ultraviolet irradiation.

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