JP2008081652A - Releasable pressure-sensitive adhesive sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a releasable pressure-sensitive adhesive sheet which has no unpleasant sticky feeling with respect to the pressure-sensitive adhesive layer and excels in various properties. <P>SOLUTION: The releasable pressure-sensitive adhesive sheet is prepared by laminating a base material, a pressure-sensitive adhesive layer, and a release sheet in this order, and the pressure-sensitive adhesive layer contains 10-20 wt.% aluminum particles and the above release sheet has peeling force, as measured by the peel test for a tape, of 800-1,600 mN/40 mm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a releasable pressure-sensitive adhesive sheet, and in particular, relates to a re-peelable pressure-sensitive adhesive sheet capable of repeatedly performing sticking and peeling on various adherends.

  A pressure-sensitive adhesive sheet in which a base material, a pressure-sensitive adhesive layer and a release sheet are laminated in this order is used for labels, seals, over a very wide range of uses such as commercial use, office use, process control use, logistics management use, and home use. It is used in the form of stickers, emblems or delivery slips.

  Examples of the pressure-sensitive adhesive sheet include a high-viscosity type having a relatively strong adhesive force, a medium-viscosity type exhibiting moderate adhesive strength, a low-viscosity type exhibiting low adhesive strength, and a low-temperature type excellent in low-temperature adhesive strength. Selected according to the application. However, all of the pressure-sensitive adhesives in these pressure-sensitive adhesive sheets are intended to be permanently or semi-permanently adhered to the adherend. Therefore, when a PSA sheet using these PSA is attached and then peeled off, the surface base material is torn, the PSA is left on the adherend, or part of the adherend is taken up by the PSA sheet. There were a lot of things that would happen. On the other hand, the re-peeling type pressure-sensitive adhesive sheet has a feature that it can repeat sticking and peeling many times, and can maintain its pressure-sensitive adhesive performance.

  As an adhesive used for the re-peeling type adhesive sheet, there is one in which a plasticizer or the like is added to the adhesive to reduce the adhesive force, but there is a problem that the peeling occurs with respect to the adherend. Moreover, about the thing which gave the unevenness | corrugation to the adhesive layer surface and reduced the adhesion area, an unevenness | corrugation becomes small by repeating peeling and sticking, and an effect diminishes.

As these solutions, the pressure-sensitive adhesive sheet containing an adhesive microsphere (see Patent Document 1), an adhesive microsphere, and an adhesive microsphere are included. An adhesive sheet (see Patent Document 2) is disclosed. In the conventional pressure-sensitive adhesive sheet in which microspheres are contained in these pressure-sensitive adhesive layers, the microspheres are made of a polymer compound or an inorganic compound.
JP-A-62-143988 Japanese Patent Laid-Open No. 11-21524

  However, the conventional pressure-sensitive adhesive sheet containing microspheres in the pressure-sensitive adhesive layer is configured to have re-peeling / re-adhesive properties by adding microspheres while giving a certain adhesive force to the pressure-sensitive adhesive layer. There is an unpleasant stickiness when touching the adhesive surface with your hand.

  An object of the present invention is to provide a releasable pressure-sensitive adhesive sheet having no unpleasant stickiness in the pressure-sensitive adhesive layer and excellent in various aptitudes.

  As a result of various investigations on components to be added to the pressure-sensitive adhesive layer in the releasable pressure-sensitive adhesive sheet, the present inventors have found that a pressure-sensitive adhesive layer with little stickiness can be formed by adding aluminum particles. And as a result of further earnest research, the base material has been subjected to sealing treatment on the pressure-sensitive adhesive layer side, and by setting the peel strength in the tape method peel test of the release sheet constituting the pressure-sensitive adhesive sheet to 800 to 1600 mN / 40 mm, It has been found that re-peelable pressure-sensitive adhesive sheets can be provided with various aptitudes.

  That is, the present invention is a releasable pressure-sensitive adhesive sheet in which a substrate, a pressure-sensitive adhesive layer, and a release sheet are laminated in this order, and the pressure-sensitive adhesive layer contains 10 to 20% by weight of aluminum particles, The base material is subjected to a sealing treatment on the surface on which the pressure-sensitive adhesive layer is laminated, and the release sheet has a peel force of 800 to 1600 mN / 40 mm as measured by a tape method peel test. As the base material, preferably, one having a sealing treatment applied to the surface on which the pressure-sensitive adhesive layer is laminated is used. In this case, the pressure-sensitive adhesive layer is preferably formed by applying a pressure-sensitive adhesive to the surface of the base material on which the sealing treatment is performed.

  The pressure-sensitive adhesive sheet according to the present invention has no unpleasant stickiness and odor, and is excellent in various suitability as a re-peelable pressure-sensitive adhesive sheet.

  The present invention is a releasable pressure-sensitive adhesive sheet in which a base material, a pressure-sensitive adhesive layer, and a release sheet are laminated in this order, and the base material contains 10 to 20% by weight of aluminum particles in the pressure-sensitive adhesive layer The release sheet has a peel force of 800 to 1600 mN / 40 mm as measured by a tape method peel test.

  In the releasable pressure-sensitive adhesive sheet according to the present invention, the main component of the pressure-sensitive adhesive used for forming the pressure-sensitive adhesive layer is preferably an acrylic polymer. Although the kind of monomer which comprises an acrylic polymer is not specifically limited, For example, methyl acrylate, ethyl acrylate, n-butyl acrylate, methyl methacrylate, isobutyl acrylate, t-butyl acrylate, n-octyl acrylate, isooctyl acrylate, 2- Acrylic acid esters, methacrylic acid esters such as ethylhexyl acrylate, isononyl acrylate, ethyl methacrylate, n-butyl acrylate, isobutyl methacrylate, and 2-ethylhexyl methacrylate; 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and 4-hydroxy Selected from the group consisting of hydroxyalkyl esters of acrylic acid such as butyl methacrylate, hydroxyalkyl esters of methacrylic acid; unsaturated aliphatic carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid and itaconic acid; and combinations thereof .

  The pressure-sensitive adhesive further contains aluminum particles. Aluminum particles contribute to reduction of stickiness generated in the pressure-sensitive adhesive layer. This is presumably because the aluminum particles lower the contact area of the pressure-sensitive adhesive layer to the adherend and the ball tack is lowered. Furthermore, the pressure-sensitive adhesive becomes hard due to the agglomeration effect caused by the reaction of the aluminum particles with the main component of the pressure-sensitive adhesive, which makes it possible to repeat re-peeling and re-adhesion of the pressure-sensitive adhesive sheet. Aluminum particles are contained in the pressure-sensitive adhesive in an amount of 10 to 20% by weight in terms of solid content. If the amount is less than 10% by weight, the effect of lowering the contact area is small and there is a sticky feeling. If the amount exceeds 20% by weight, the contact area is too low and the adhesive strength is lowered, resulting in poor suitability as an adhesive sheet. The material of the aluminum particles in the present invention may be aluminum as long as the main component, that is, the component occupying 50% by weight or more of the whole, is preferable as the purity of aluminum is higher, and pure aluminum is particularly preferable. When a component other than aluminum is contained, the component is not particularly limited.

  The shape of the aluminum particles is not particularly limited, and may be various shapes such as a granular shape, a plate shape, a lump shape, and a flake shape (scale shape). The average particle diameter of the aluminum particles is preferably 1 to 10 μm. If the thickness is less than 1 μm, there is no effect of lowering the contact area with the adherend, and re-peeling becomes difficult. If the thickness exceeds 10 μm, the contact area with the adherend decreases too much and the adhesive strength decreases. The average particle diameter of the aluminum particles here is a value measured by a laser diffraction light scattering method. As will be described later, it is preferable to form the adhesive layer by directly applying the adhesive to the substrate.

As the base paper of the release sheet used for the releasable pressure-sensitive adhesive sheet according to the present invention, glassine paper, clay-coated paper, kraft paper, or high-quality paper that has been subjected to sealing treatment can be used. The base paper has a release layer on its surface (the surface on which the sealing process is performed when the sealing process is performed). As the release agent, a heavy release type silicone release agent having a molar ratio of hydrogen atoms bonded to silicon atoms to a vinyl group bonded to silicon atoms (SiH / SiVi ratio) of 2.0 to 3.0 is used. The release agent has a resin structure having SiO ₂ units and (CH ₃ ) ₃ SiO _1/2 units or CH ₂ ═CH (CH ₃ ) ₂ SiO _1/2 units, and a silica structure having SiO ₂ units. It is prepared by adding a heavy release additive having Although it does not specifically limit as a coating amount, About 0.5-1.0 g / m < ² > is preferable at solid content conversion.

  In the tape method peel test described below, the peel sheet preferably has a peel force of 800 to 1600 mN / 40 mm, particularly 1000 to 1400 mN / 40 mm. If it is less than 800 mN / 40 mm, floating (tunneling) is likely to occur between the pressure-sensitive adhesive layer on the base material and the release sheet when the pressure-sensitive adhesive sheet is wound, and unnecessary parts are formed by cutting the base material of the pressure-sensitive adhesive sheet. Unnecessary parts are not separated cleanly from the necessary parts when removed, and the phenomenon that the necessary parts are peeled off is likely to occur. If it exceeds 1600 mN / 40 mm, it is not necessary to cut the adhesive sheet substrate and remove the unnecessary parts. It is divided within the region of the portion (scrap breakage), and an inconvenience that unnecessary portions cannot be removed at once is likely to occur.

  It does not specifically limit as a base material used for the adhesive sheet of this invention. For example, in addition to paper substrates such as fine paper, coated paper, art paper, cast coated paper, thermal transfer recording paper, ink jet recording paper, thermal recording paper, pressure sensitive recording paper, etc., as a film, polypropylene resin synthetic paper, polyethylene resin Synthetic paper, cellophane film, nylon film, acetyl cellulose resin film, polyvinyl chloride resin film, polyolefin resin film such as polypropylene resin and polyethylene resin, polyamide resin film such as aromatic polyamide, polyimide resin, bismaleimide / triazine resin, Polyimide resin films such as polyamideimide resin and polyamide bismaleimide resin, epoxy resin, polyacetal resin, polyphenylene oxide resin, modified polyphenylene oxide resin, polyether ether ketone resin, polyester Polyether resin films such as ether sulfone resins and polysulfone resins, polyarylate resins, polycarbonate resins, polyoxybenzoate resins, polyester resin films such as polyethylene terephthalate resins, and metal foils such as aluminum, copper, tin, and tin Is mentioned. Although it does not specifically limit as thickness of a base material, Preferably it is 30-200 micrometers, Most preferably, the thing of the range of 50-120 micrometers is used.

  Formation of the pressure-sensitive adhesive layer using the pressure-sensitive adhesive of the present invention is performed by directly applying a pressure-sensitive adhesive on the surface of the substrate, drying to provide a pressure-sensitive adhesive layer, and bonding the release sheet, or a release sheet release agent. An adhesive is applied to the coated surface and dried to form an adhesive layer, and then the indirect coating method or the like in which the substrates are bonded together, preferably by the direct coating method. This is because the pressure-sensitive adhesive used in the present invention that can be re-peeled and re-adhered has poor anchoring properties to the base material during the indirect coating method.

  When the pressure-sensitive adhesive layer is formed by a direct coating method, the adhesive-coated surface of the substrate is preferably subjected to a sealing treatment in order to suppress penetration of the pressure-sensitive adhesive by direct coating. Sealing treatment includes, for example, pigments such as clay, talc, and calcium carbonate; laminate of resin film such as polyethylene; ethylene-vinyl acetate copolymer, silica-modified polyvinyl alcohol, styrene-butadiene copolymer, acrylate ester copolymer It depends on the synthetic polymer. If a base material that is not configured to suppress the penetration of the adhesive, for example, is not subjected to sealing treatment, the adhesive is impregnated to obtain a predetermined effective coating amount having an adhesive effect. Is unfavorable because a large amount of actual coating is required and odor is generated by a large amount of the adhesive contained in the substrate.

  The pressure-sensitive adhesive is preferably applied directly on the substrate as described above. In this case, the pressure-sensitive adhesive prepared as described above is used, for example, a roll coater, an air knife coater, a bar coater, a comma coater, or a blade coater. The pressure-sensitive adhesive layer is formed by coating and drying on the above-mentioned sealing treatment surface of the substrate by, for example, and bonding with the release sheet to produce the pressure-sensitive adhesive sheet. Coating is performed so that the effective coating thickness after drying is preferably 5 to 15 μm. The effective coating thickness is the coating thickness excluding the amount penetrating into the base material. The thickness of the base material before coating is determined from the combined thickness of the base material and adhesive layer after application of the adhesive. Calculated by subtracting.

  The pressure-sensitive adhesive sheet according to the present invention is preferably used for applications where a configuration capable of re-peeling and re-adhering is useful, and is particularly preferable for application to an adherend surface having smoothness.

(Tape peeling test)
A standard tape (Nitto Denko, No. 31B, 40 mm width) is attached to a release sheet adjusted to a temperature of 23 ° C. and a humidity of 50% with a length of 200 mm, and one reciprocating press with a 2 kg rubber roller. The sample was sandwiched between glass plates, subjected to a load of 20 g / cm ² and aged at 70 ° C. for 20 hours, allowed to cool at 23 ° C. and 50% humidity for 3 hours, and then a tensile tester (manufactured by Shimadzu Corporation, AGS- 500 NG), the peeling force (unit: mN / 40 mm) is measured at a peeling speed of 300 mm / min and a peeling angle of 180 °.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

(Production method)
Each releasable adhesive sheet of Examples 1-6 and Comparative Examples 1-5 was produced as follows.

1. As a base material that has been subjected to a base sealing process, a coated paper (manufactured by Daio Paper Co., Ltd., Utrilo Coat 84.9 g / m ² , a sealing process with a sealing agent containing clay and calcium carbonate has been applied. Used). In Comparative Examples 3 and 4, high-quality paper (manufactured by Daio Paper Co., Ltd., 64 g / m ² ) was used as a base material that was not subjected to sealing.

2. Peeling sheet release agent (Toray Dow Corning, BY24-312) 100 parts by weight, heavy release additive (Toray Dow Corning, BY24-843) added in parts by weight listed in Table 1 An agent solution was obtained. In addition, all the parts in Table 1 are the weight of an active ingredient. The release sheet of each Example and each Comparative Example was prepared by applying this release agent solution to a high-quality paper (73 g / m ² ) having a polyethylene laminate as a filler so as to have the dry weight shown in Table 1. It was. Table 1 shows the results of measuring the peel force by the above-described tape method peel test for each release sheet.

3. A pressure-sensitive adhesive containing 15% by weight of pressure-sensitive aluminum particles (average particle size: 5 μm) (manufactured by Hakubi Chemical Co., Ltd., Magic Tack) was used, and the pressure-sensitive adhesive layer was adjusted to have an effective coating thickness shown in Table 1. In addition, the comparative example 1 used the re-peeling / re-adhesion type pressure-sensitive adhesive (N-Carbide, B-7687) containing microspheres made of an acrylate resin.
(Evaluation methods)
The following evaluation test was performed about each releasable adhesive sheet produced as mentioned above.

1. Adhesive evaluation An adhesive sheet cut to a size of 20 cm × 20 cm was attached to a glass plate, and the situation after 24 hours was visually confirmed. The evaluation results are shown in Table 1.
◯: Floating and peeling were not seen at all.
X: Floating and peeling occurred partially.

2. Touch the pressure-sensitive adhesive layer surface of the sticky evaluation pressure-sensitive adhesive sheet and the pressure-sensitive adhesive layer surface of ordinary tack paper (manufactured by Elle Texell, Inc., general high-viscosity tack paper) with fingertips to touch each example and each comparative example. The sticky feeling of the pressure-sensitive adhesive sheet was evaluated by 20 people in comparison with the tack paper. The evaluation results are shown in Table 1.
O: 80% or more of the people evaluated that there was no stickiness.
X: More than half of the people evaluated that there was a sticky feeling.

3. Odor Evaluation 20 persons were evaluated for odor by comparing the pressure-sensitive adhesive sheet cut to a size of 20 cm × 20 cm with the above normal tack paper. The evaluation results are shown in Table 1.
A: 80% or more of the people evaluated that there was no difference or that there was little odor.
X: More than half of the people evaluated that there was a smell.

4). Tunneling Evaluation A 5,000-m winding was performed with a real machine tack coater (manufactured by Eliere Texel), and the presence or absence of tunneling was confirmed on the winding side surface and evaluated as follows. The evaluation results are shown in Table 1.
A: Tunneling was not seen at all.
〇: Floating, but not tunneled.
X: There was a part floating clearly, and a lot of tunneling was seen.

5. Appropriateness of residue raising After a die was cut in 30 mm square (cut into the base material) with a real printing press, the residue was raised at a width of 5 mm and evaluated. The evaluation results are shown in Table 1.
A: No scum breakage or rise was observed.
O T: There was a part that floated at the end of the punching process, but it did not go up.
◯ K: There was a portion where a crack was formed in the residue, but the residue was not cut.
× T: A rise occurred.
× K: Broken residue occurred.

表１に示す結果からわかるように、実施例１〜６の粘着シートは、臭気、ベタツキがなく、また十分な粘着性を有し、トンネリングの発生がなく、カス上げ適性も備えることが確認された。

As can be seen from the results shown in Table 1, it was confirmed that the pressure-sensitive adhesive sheets of Examples 1 to 6 were free from odor and stickiness, had sufficient tackiness, did not cause tunneling, and had a residue raising ability. It was.

  The present invention can be used for various applications as a re-peelable pressure-sensitive adhesive sheet having no odor and stickiness and having excellent usability. Also, since there is no tunneling and it is excellent in scrap raising ability, it is stored in a wound state, and is used after being die-cut to an appropriate size and lifted, for example, re-peeling Suitable for labels, slips, stickers, etc.

Claims (1)

A releasable pressure-sensitive adhesive sheet in which a base material, a pressure-sensitive adhesive layer and a release sheet are laminated in this order,
The pressure-sensitive adhesive layer contains 10 to 20% by weight of aluminum particles,
The base material is subjected to a sealing treatment on the surface on which the pressure-sensitive adhesive layer is laminated,
The said peelable sheet is a releasable adhesive sheet whose peeling force measured by a tape method peel test is 800-1600mN / 40mm.