JPH07216320A - Removable adhesive sheet - Google Patents

Abstract

(57) [Abstract] [Purpose] A removable pressure-sensitive adhesive sheet using pressure-sensitive adhesive microspheres, and when the pressure-sensitive adhesive microspheres in the pressure-sensitive adhesive layer are handled in a roll-up form, the effect of the tightening pressure of the roll-up is considered. (EN) Provided is a removable pressure-sensitive adhesive sheet which exhibits a sufficient protective function and is excellent in performance that can be repeatedly adhered and peeled on various adherends even after being stored after being wound and stored. [Structure] A releasable pressure-sensitive adhesive sheet obtained by laminating a surface substrate, a pressure-sensitive adhesive layer composed of a pressure-sensitive adhesive microsphere and an adhesive, and a release sheet, wherein the pressure-sensitive adhesive layer further has an average particle diameter of the pressure-sensitive adhesive microsphere. It is a removable pressure-sensitive adhesive sheet containing non-adhesive fine particles having an average particle diameter of 10 to 80% at a compounding ratio of 1 to 50 parts by weight with respect to 100 parts by weight of adhesive microspheres.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a releasable pressure-sensitive adhesive sheet which uses pressure-sensitive adhesive microspheres and which can be repeatedly used for sticking to and peeling from an adherend.

[0002]

2. Description of the Related Art Adhesive sheets are processed into labels, stickers, stickers, patches, etc. for a wide range of uses such as commercial use, office use, and household use. The general structure of such an adhesive sheet is such that an adhesive is sandwiched between a surface base material and a release sheet.

Such pressure-sensitive adhesive sheets are roughly classified into a permanent adhesive type and a re-peelable type, according to the function of the pressure-sensitive adhesive used. The pressure-sensitive adhesives used in permanent adhesive pressure-sensitive adhesive sheets are changing from rubber type to acrylic type and solvent type to aqueous emulsion type. Especially, permanent adhesive type pressure-sensitive adhesive sheets for labels are mostly emulsion type acrylic type pressure-sensitive adhesives. Became occupied with.

On the other hand, some proposals have been made for emulsion type acrylic pressure-sensitive adhesives as the removable pressure-sensitive adhesives, but these are generally of the type which is cross-linked with an epoxy-type curing agent, such as metals and plastics. It exhibits excellent removability for adherends with strong surface strength such as, but for adherends with weak surface strength such as paper, cardboard, etc. At present, it is difficult to produce a product having poor removability and having sufficient removability.

The re-peelable pressure-sensitive adhesive sheet currently demanded has the following properties after a certain period of time elapses from the adherend once adhered.
It must be able to be peeled off neatly without damaging the adherend if necessary.

Recently, a pressure-sensitive adhesive sheet of the type in which a pressure-sensitive adhesive microsphere is directly applied to a surface substrate has been attracting attention as a removable pressure-sensitive adhesive sheet that can be repeatedly attached and peeled from an adherend. However, the existing re-peelable pressure-sensitive adhesive sheet that uses the adhesive microspheres as they are is finished in the form of winding in the manufacturing process, and therefore the state where the adhesive microspheres are crushed due to the influence of the winding tightening pressure. It has been used by being stuck without the original performance being fully exhibited.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a releasable pressure-sensitive adhesive sheet using pressure-sensitive adhesive microspheres, which is used when the pressure-sensitive adhesive microspheres in the pressure-sensitive adhesive layer are handled in a roll-up form. To provide an excellent re-peelable pressure-sensitive adhesive sheet capable of sufficiently exerting a protective function against the influence of the tightening pressure of, and capable of repeatedly adhering and peeling to various adherends even after storing and winding up for a long time. is there.

[0008]

The present invention is a removable pressure-sensitive adhesive sheet comprising a surface substrate, a pressure-sensitive adhesive layer composed of a pressure-sensitive adhesive microsphere and an adhesive, and a release sheet, wherein the pressure-sensitive adhesive layer further comprises: 10 to 80% of the average particle size of the adhesive microspheres
Non-adhesive fine particles having an average particle diameter of 1 to 50 parts by weight of non-adhesive fine particles with respect to 100 parts by weight of adhesive microspheres in a solid content weight ratio. It is a peelable adhesive sheet.

[0009]

The non-adhesive fine particles of the present invention include, for example,
Examples thereof include starch particles, cellulose particles, organic particles such as synthetic resin particles, and inorganic particles such as calcium carbonate, titanium oxide and silica, and surface-treated particles can also be used. Further, the shape is not particularly limited, such as spherical, needle-like, hollow, and porous. The non-adhesive fine particles may be heat-expandable microcapsules. Needless to say, in order to exert the effect of the present invention, the non-adhesive fine particles are added in a granular state.

By containing non-adhesive fine particles in the adhesive layer,
It is important that the particle size of the non-adhesive microparticles is smaller than the particle size of the adhesive microspheres in order to protect the adhesive microspheres and not to lose the adhesiveness of the adhesive layer. . The average particle size of the non-adhesive fine particles is 10 to 80% of the average particle size of the adhesive microspheres, more preferably 30 to
It is 50% in size. Incidentally, if the average particle size of the non-adhesive fine particles is less than 10% of the average particle size of the adhesive microspheres, the protective function is insufficient, while if it exceeds 80%, the adhesive microspheres adhere to the surface. It becomes an obstacle when it comes into contact with the body, and the adhesive strength is extremely reduced.

The compounding ratio of the adhesive microspheres and the non-adhesive fine particles in the adhesive layer is also important. This blending ratio must be adjusted in the range of 1 to 50 parts by weight of non-adhesive fine particles, more preferably 10 to 30 parts by weight, based on 100 parts by weight of adhesive microspheres in terms of solid content weight ratio. I won't. By the way, if the blending ratio is less than 1 part by weight, the protective function against the adhesive microspheres is insufficient, and
If the amount exceeds 0 parts by weight, the non-adhesive portion in the pressure-sensitive adhesive layer increases and the adhesive strength is extremely reduced.

The sticky microspheres used in the present invention include ethyl acrylate, propyl acrylate, n-butyl acrylate, isopropyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, isononyl acrylate and lauryl. Acrylate, methylmethacrylate, propylmethacrylate, butylmethacrylate, 2-ethylhexylmethacrylate, isononylmethacrylate, laurylmethacrylate, etc. (meth) acrylic acid ester as a main component, these monomers and acrylic acid, methacrylic acid, itaconic acid, Crotonic acid, maleic acid, 2-hydroxyethyl (meth) acrylate,
Hydroxypropyl (meth) acrylate, N-methylol (meth) acrylamide, (meth) acrylamide, glycidyl (meth) acrylate, glycidyl ether (meth) acrylate, vinyl acetate, styrene,
(Meth) acrylonitrile, trimethylamine (meth)
Acrylamide, trimethylamine-p-vinylbenzimide, ammonium (meth) acrylate, sodium (meth) acrylate, N, N-dimethyl-N- (β
-(Meth) acryloxylethyl) ammonium propione-tobetaine, 1,1-dimethyl-1- (2-hydroxypropyl) amine (meth) acrylimide,
4,4,9-Trimethyl-4-azonia-7-oxy-
9-decene-1-sulfonate, 1,1-dimethyl-1
It can be produced by copolymerizing a monomer such as-(2,3-dihydroxypropyl) amine (meth) acrylimide into a sphere.

A specific manufacturing method is described, for example, in JP-A-50-2736 and 61-14827.
It can be produced by the suspension polymerization method described in, for example, JP-A-8. The particle size of the adhesive microspheres is adjusted to an average particle size of 10 to 100 μm in accordance with the adhesiveness and coatability.

The method of applying the pressure-sensitive adhesive is as follows. An adhesive is added to and mixed with an aqueous dispersion of the pressure-sensitive adhesive microspheres obtained by the suspension polymerization, non-adhesive fine particles are added, and if necessary. It is possible to prepare a pressure-sensitive adhesive paint as a water-dispersed paint together with other auxiliaries. As a coating method, a usual coating machine, for example, a knife coater, a roll coater, a comma coater, a bar coater, a gravure coater, a lip coater, a die coater, screen printing or the like can be used.

In this case, the pressure-sensitive adhesive application surface is the back surface of the front surface base material, and the pressure-sensitive adhesive is transferred to the front surface base material by applying the pressure-sensitive adhesive to the release sheet side and pasting the front surface base material together. Unlike the method, it must be a direct method that is applied directly to the surface substrate.

Regarding this, as the constituents of the pressure-sensitive adhesive layer, as described above, the adhesive microspheres, non-adhesive fine particles,
And adhesives (bonding agents) that fix them to surface substrates
There is no stickiness in this adhesive,
If the adhesive microspheres are not exposed on the surface of the adhesive, the function as an adhesive sheet will not appear. In other words, the transfer method results in the adhesive covering the sticky microspheres, and the practical effect cannot be obtained.

In this case, the coating amount of the pressure-sensitive adhesive layer is such that the weight of the pressure-sensitive adhesive microspheres in the pressure-sensitive adhesive layer is 5 to 50 g / m ² in terms of dry solid content, preferably 10 to 30 g / m ² . . Incidentally, if it is less than 5 g / m ² , the effect as a pressure-sensitive adhesive layer is poor, and if it exceeds 50 g / m ² , it is not necessary in terms of economy.

The surface substrate used in the present invention includes paper, synthetic paper, cloth, non-woven fabric, metal foil, various polymer films, etc., and a natural or synthetic resin may be used alone or on the back surface of the surface substrate. It may be provided with layers.

The release sheet may be glassine paper.
Una high density base paper, clay coated paper, kraft paper and fine paper
To the laminated paper etc. which laminated polyethylene etc.
A product coated with a fluorine-based release agent or a silicone-based release agent should be used.
Used. The method of applying the release agent is a normal coating machine, for example,
For bar coaters, roll coaters, gravure coaters, etc.
Therefore, it can be performed. In this case, the coating amount is
Amount of 0.05-3g / m², Preferably 0.2 to 1.5
g / m²Is appropriate. By the way, 0.05g / m ²Less than
Has a poor effect as a release agent layer, and is 3 g / m²Over
It is economically unnecessary to obtain it. Also especially
If there is no limit to the peeling force, you can use polylaminate base paper alone.
Can be used.

Such a releasable pressure-sensitive adhesive sheet of the present invention is obtained by applying a dispersion containing adhesive microspheres, an adhesive and further non-adhesive fine particles to a surface substrate and then bonding the release sheet and a nip roll. It is obtained by doing.

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In addition, the coating amount, the number of parts, the mixing ratio, and the like in the examples are all shown by the solid content weight.

Example 1 "Preparation of Release Sheet" A commercially available glassine paper having a basis weight of 70 g / m ² and a silicone release agent (trade name "BY24-312" manufactured by Torre Dow Corning Co., Ltd.) were used in a dry weight of 1. 0
It was applied by a bar coater so as to be g / m ^2, and then dried and cured in a drying oven at a temperature of 140 ° C. for 1 minute to prepare a release sheet.

"Preparation of adhesive coating" A dispersion containing adhesive microspheres as an adhesive component and an adhesive as a main component (manufactured by Nippon Carbide Co., Ltd., trade name "Nikazol TS-5000-5"
0 ”, average particle diameter: about 50 μm, solid content concentration: 27%,
100 parts by weight of solid content as sticky microspheres having a ratio of sticky microspheres to adhesive of 100: 25), and non-sticky fine particles having an average particle diameter of about 18 μm flour starch granules (manufactured by Glico Nutrition Foods Co., 30 parts by weight of the product name "Glyco B") was added and stirred for 30 minutes to prepare the pressure-sensitive adhesive coating of the present invention.

"Preparation of adhesive sheet" Commercially available rice bed of 64 g /
a fine paper of m ^2, an adhesive coating obtained by the above method, the dry weight is applied using a lip coater so that 20 g / m ^2, and dried for 2 minutes in the subsequent drying oven temperature 100 ° C.. Then, the release sheet obtained by the above method was attached to the surface of the pressure-sensitive adhesive layer to obtain a removable pressure-sensitive adhesive sheet of the present invention.

Example 2 A removable pressure-sensitive adhesive sheet of the present invention was obtained in the same manner as in Example 1 except that 10 parts by weight of wheat starch starch particles were added.

Example 3 The removable pressure-sensitive adhesive sheet of the present invention was prepared in the same manner as in Example 1 except that 50 parts by weight of wheat starch starch particles were added and the adhesive paint was applied at 25 g / m ^2. Obtained.

Comparative Example 1 A releasable pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that 0.5 part by weight of wheat starch starch particles was added.

Comparative Example 2 The removable pressure-sensitive adhesive sheet of the present invention was prepared in the same manner as in Example 1 except that 60 parts by weight of flour starch granules were added and the pressure-sensitive adhesive paint was applied at 25 g / m ^2. Obtained.

Example 4 In Example 1, except that 1 part by weight of silicon dioxide particles (trade name "Carplex # 80" manufactured by Shionogi Seiyaku Co., Ltd.) having an average particle size of about 7 μm were added as non-adhesive fine particles. In the same manner as in Example 1, a removable pressure-sensitive adhesive sheet of the present invention was obtained.

Example 5 In Example 1, except that 40 parts by weight of calcium carbonate particles (trade name "KD-70" manufactured by Dowa Calfine Co., Ltd.) having an average particle size of about 17 μm were added as non-adhesive fine particles. In the same manner as in Example 1, a removable pressure-sensitive adhesive sheet of the present invention was obtained.

Example 6 In Example 1, as non-adhesive fine particles, cellulose particles having an average particle size of about 23 μm (Germany / Rettema) were used.
Product name "Avocell BE6" manufactured by ier & Sheene
00-20 ") is added and the adhesive paint is added to 25
A releasable pressure-sensitive adhesive sheet of the present invention was obtained in the same manner as in Example 1 except that g / m ^{2 was} applied.

Example 7 In Example 6, as the dispersion liquid containing the adhesive microspheres as the adhesive component and the adhesive as the main component, a dispersion liquid having an average particle diameter of the adhesive microspheres of about 30 μm (Nippon Carbide Co.) Made by
This product was prepared in the same manner as in Example 6 except that the trade name "Nikazol TS-5000-30", the average particle size: about 30 μm, the solid content concentration: 27%, and the ratio of the adhesive microspheres to the adhesive 100: 25) were used. The removable pressure-sensitive adhesive sheet of the invention was obtained.

Comparative Example 3 In Example 7, as non-adhesive fine particles, cellulose particles having an average particle size of about 30 μm (Germany / Rettema) were used.
Product name "Avocell BE6" manufactured by ier & Sheene
00-30 ") was added and a re-peelable pressure-sensitive adhesive sheet was obtained in the same manner as in Example 7.

Comparative Example 4 In Example 4, the average particle diameter of the adhesive microspheres was about 80 μm as a dispersion containing the adhesive microspheres and the adhesive as the main components.
Dispersion (manufactured by Nippon Carbide Co., trade name “Nikazol TS-5000-80”, average particle size: about 80 μm,
Solid content concentration: 27%, ratio of adhesive microspheres to adhesive 10
0:25), and a removable pressure-sensitive adhesive sheet was obtained in the same manner as in Example 4 except that 20 parts by weight of silicon dioxide particles were added as non-adhesive fine particles.

Comparative Example 5 Adhesive dispersion containing adhesive microspheres and an adhesive as main components (manufactured by Nippon Carbide Co., trade name "Nikazol TS-5000"
-50 ", solid content concentration: 27%), non-adhesive fine particles were added as they were, and the releasable adhesive sheet was applied in the same manner as in Example 1 except that the adhesive paint was applied at 15 g / m ^2. Got

The pressure-sensitive adhesive sheet thus obtained was further processed into a small slitter (manufactured by Nishimura Seisakusho, "TB-2").
With a paper tube with an inner diameter of 3 inches and a wall thickness of 8 mm, a width of 180 m
m and a length of 300 m were wound to prepare a small roll of the removable pressure-sensitive adhesive sheet. In addition, the hardness of each winding is determined by a pressure hardness tester (Switzerland / Schmidt,
As a result of measurement with "Schmidt test hammer LR type"), the resilience was in the range of 30 ± 2.

With respect to the removable pressure-sensitive adhesive sheet thus obtained, the adhesive performance was evaluated by the following method on the day of work, and after one month for the small roll-up of the removable pressure-sensitive adhesive sheet, the following results were evaluated. It is described in Table 1.

Evaluation method [Adhesive strength] Based on JIS Z 0237 180 ° peeling method, high-quality paper of 64 g / m ² of tsubo (manufactured by Shin-Oji Paper Co., Ltd., “NWF5”)
5 ") was measured. (Unit: g / 25m
m) [Edge lift] On the surface of a stainless steel pipe with a diameter of 34 mm, a high-quality paper of 64 g / m ² in weight (made by Shin Oji Paper Co., Ltd.,
"NWF55") is rolled to form a curved adherend.
Next, the pressure-sensitive adhesive sheet was cut into 25 mm × 30 mm, the release sheet was peeled off and attached to the adherend, and the floating of the test piece was observed after 3 days. ◯: No floating of the test piece was observed, and the adhesiveness to the adherend was good. Δ: Some floating of the test piece was seen. X: The test piece was completely floating from the adherend. [Removability] The pressure-sensitive adhesive sheet was cut into 25 mm × 90 mm, the release paper was peeled off, and then 10 g of a high-quality paper of 64 g / m ² (Shin-Oji Paper Co., Ltd., “NWF55”) with a 2 Kg roller was used. It reciprocated and crimped. 3 days later, 10m / min
The test piece was peeled at a speed of. ◯: No adherent was left on the adherend, and the base material was peeled off without breakage. X: The adhesive remained on the adherend or the base material was broken. [Repeated Removable Adhesive Strength] The adhesive strength was measured when the above-mentioned adhesion and repeeling were repeated 5 times.

[0039]

[Table 1]

[0040]

As is clear from the results shown in Table 1, the removable pressure-sensitive adhesive sheet of the present invention has a small decrease in adhesive strength even after a lapse of time of winding and manufacturing, and has excellent removability after repeated repeeling. It was an adhesive sheet.

Claims (3)

[Claims] 1. A releasable pressure-sensitive adhesive sheet comprising a surface substrate, a pressure-sensitive adhesive layer comprising a pressure-sensitive adhesive microsphere and an adhesive, and a release sheet, wherein the pressure-sensitive adhesive layer further comprises an average particle diameter of the pressure-sensitive adhesive microsphere. Non-adhesive fine particles having an average particle diameter of 10 to 80% with respect to 100 parts by weight of the adhesive microspheres in a solid content weight ratio, in a mixing ratio of 1 to 50 parts by weight of non-adhesive fine particles. A removable pressure-sensitive adhesive sheet characterized by being. 2. The removable pressure-sensitive adhesive sheet according to claim 1, wherein the non-adhesive fine particles have an average particle size of 30 to 50% of the average particle size of the adhesive microspheres. 3. The removability according to claim 1, wherein the adhesive layer has a blending ratio of 10 to 30 parts by weight of non-adhesive fine particles to 100 parts by weight of adhesive microspheres in terms of solid content weight ratio. Adhesive sheet.