JPH08183936A - Re-releasable pressure-sensitive adhesive sheet - Google Patents

Abstract

PURPOSE: To obtain a re-releasable pressure-sensitive adhesive sheet provided with excellent re-releasability and workability for esp. video cassettes, audio cassettes, floppy disks, etc. CONSTITUTION: This re-releasable pressure-sensitive adhesive sheet is a laminate made up of at least a release sheet, a pressure-sensitive adhesive layer and a surface base material. The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer comprises a copolymer, a crosslinking agent, and 3-50 pts.wt., based on 100 pts.wt. of the copolymer, of a tackifier consisting of rosin-based resin and/or terpene-based resin. The copolymer is made from (a) 0.1-5wt.% of a monomer including an ethylenic unsaturated carboxylic acid, (b) 65-98wt.% of a (meth)acrylic 4-10C alkyl ester, and (c) 1-30wt.% of another monomer copolymerizable therewith.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a removable pressure sensitive adhesive sheet, and more particularly to a removable pressure sensitive adhesive sheet having excellent removable property and workability for video cassettes, audio cassettes, floppy disks and the like.

[0002]

2. Description of the Related Art Adhesive sheets are used for labels, stickers, stickers, etc.
It is used after being processed into patches. The basic structure of the pressure-sensitive adhesive sheet is such that a pressure-sensitive adhesive layer is sandwiched between a surface base material and a release sheet. And
Paper, film, metal foil, etc. are used for the surface substrate, and high-density base paper such as glassine paper, clay-coated paper, polyethylene laminated base paper, etc. are coated with release agents such as silicone compounds and fluorine compounds as release sheets. What is done is used. As the pressure-sensitive adhesive, various types of rubber-based, acrylic-based, vinyl ether-based emulsion, solvent or solventless pressure-sensitive adhesives are used. Such an adhesive sheet is a permanent adhesive type that is permanently used while being attached to an adherend after being attached to a product or the like, and is peeled off after the display purpose is achieved from the purpose of use of the product or the like. ,
Some are removable and some are removable.

Conventionally, a re-peelable pressure-sensitive adhesive sheet has been widely used for applications such as video cassettes, audio cassettes, floppy disks, etc., in which recording of images, music and the like can be repeated as many times as desired. For adhesive sheets for such applications, if the label pops up inside equipment such as a video cassette deck, it will cause machine failure.Therefore, there is no unnecessary label pop-up during the application period. Is required. Further, when a tape, an image in the disc, music, or the like is newly recorded, a new label is required, and the previous label is peeled and discarded. In that case, it is necessary that the top paper is not torn and that there is no adhesive residue on the adherend such as the cassette or the disc, so that it can be easily peeled off.

By the way, most of the removable pressure-sensitive adhesive sheets currently used for applications such as video cassettes, audio cassettes, floppy disks, etc. do not cause unnecessary label floating during the application period, but are not easily removed during peeling. There are problems such as paper tears and adhesive residue, or excellent removability, but unnecessary label lifting during the application (required) period, etc. The reality is that they do not.

[0005]

DISCLOSURE OF THE INVENTION The present invention is particularly suitable for video cassettes, audio cassettes, floppy discs, etc. without the need for unnecessary lifting of the label at the time of sticking and having excellent re-peeling suitability at the time of peeling. A peelable pressure-sensitive adhesive sheet is provided.

[0006]

[Means for Solving the Problems] In order to achieve the above objects, the present inventors have conducted extensive research. As a result, in the pressure-sensitive adhesive sheet according to the present invention, the pressure-sensitive adhesive, which is one of the constituent components, is a copolymer composed of specific monomers, and the crosslinking agent and the tackifier were added to the copolymer. It consists of things.

That is, in the present invention, in a re-peelable pressure-sensitive adhesive sheet comprising at least a release sheet, a pressure-sensitive adhesive layer, and a surface base material laminated, the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer comprises the following monomers. Copolymer, cross-linking agent, and copolymer 10
A removable pressure-sensitive adhesive sheet, characterized in that 3 to 50 parts by weight of a tackifier is added to 0 parts by weight. (A) an ethylenically unsaturated carboxylic acid-containing monomers: from 0.1 to 5 wt% (b) (meth) C ₄ -C ₁₀ alkyl ester monomers of acrylic acid: 65 to 98 wt% (c) These Other monomers copolymerizable with the above monomer: 1 to 30% by weight

[0008]

The adhesive used in the present invention is (a) an ethylenically unsaturated carboxylic acid-containing monomer, (b) as described above.
(Meth) C ₄ -C ₁₀ alkyl ester monomer, and (c) the monomer and other copolymerizable monomers of acrylic acid, a copolymer consisting of. Specific examples of the (a) ethylenically unsaturated carboxylic acid-containing monomer include acrylic acid, methacrylic acid, itaconic acid, maleic acid and fumaric acid. In addition,
The amount of the ethylenically unsaturated carboxylic acid-containing monomer used is 0.1 to 5% by weight relative to the total amount of all the monomers. By the way, if it is less than 0.1%, the adhesive force and the adhesive force will be lowered, while if it exceeds 5%, the obtained adhesive will be susceptible to humidity deterioration and the like.

Further, (b) C ₄ -of (meth) acrylic acid
Specific examples of the C ₁₀ alkyl ester monomer include butyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, isononyl acrylate and the like. The amount of the above alkyl ester monomer used is 65 to 98% by weight relative to the total amount of all the monomers. Incidentally, if it is less than 65%, the adhesive force of the obtained adhesive to the adherend is too weak, and the problem of floating of the label occurs. On the other hand, if it exceeds 98%, the adhesive force of the obtained adhesive to the adherend is too strong, which causes a problem of poor removability due to paper breakage or contamination of the adherend.

Next, specific examples of other monomers copolymerizable with the monomers (a) and (b) include methyl acrylate, methyl methacrylate, ethyl acrylate,
Acrylic acid alkyl esters and methacrylic acid alkyl esters having an alkyl group of 3 or less carbon atoms such as ethyl methacrylate, isopropyl acrylate and isopropyl methacrylate, hydroxyalkyl acrylates such as hydroxyethyl acrylate and hydroxyethyl methacrylate, and methacrylic acid Acid hydroxyalkyl ester, methoxyethyl acrylate, ethoxymethyl acrylate, etc. Acrylic acid alkoxyalkyl ester and methacrylic acid alkoxyalkyl ester, glycidyl acrylate, glycidyl acrylate and glycidyl methacrylate, acrylonitrile, methacrylic acid Nitriles such as ronitrile, acrylamide, methacrylamide,
Examples thereof include amides such as N-methylolacrylamide, N-methoxymethylacrylamide and N-methoxybutylacrylamide, and aromatic unsaturated hydrocarbons such as styrene and α-methylstyrene.

The amount of these other monomers used is 1 to 30% by weight relative to the total amount of all the monomers. By the way, 1
If it is less than%, the adhesive strength is too strong, causing paper breakage due to poor removability and causing a problem of contamination of the adherend. On the other hand, 30%
If it exceeds, the adhesive force of the obtained adhesive to the adherend is too weak and the problem of floating of the label occurs.

In the pressure-sensitive adhesive sheet of the present invention, the pressure-sensitive adhesive used is, as described above, a copolymer containing the above-mentioned specific monomer, to which a crosslinking agent and a specific tackifier are further added. It is characterized by that. A polyglycidyl compound is used as the crosslinking agent. In that case, the addition amount is 0.1 to 100 parts by weight of the copolymer.
It is adjusted in the range of 10 parts by weight. Incidentally, if the amount is less than 0.1 parts by weight, the adhesive force of the obtained pressure-sensitive adhesive to the adherend is too strong to easily cause adhesive residue, while if it exceeds 10 parts by weight, the obtained pressure-sensitive adhesive is anchored to the substrate. There is a risk that the sex will deteriorate.

Specific examples of the polyglycidyl compound used as the cross-linking agent include ethylene glycol or polyethylene glycol diglycidyl ether, propylene glycol or polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, and 1,6-hexanediol. Diglycidyl ether, dibromoneopentyl glycol diglycidyl ether, o-phthalic acid diglycidyl ester, glycerin polyglycidyl ether, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, etc. Can be mentioned. In addition, N, N, N ', N'-tetraglycidyl-m-xylenediamine, N, N, N',
N ", N" -pentaglycidyl diethylenetriamine and the like can be mentioned.

As the tackifier, at least one selected from terpene resins and rosin resins is used. Examples of the terpene-based resin include α- or β-pinene-based, dipentene-based, terpene-phenolic and other terpene-based resins, and examples of the rosin-based resin include gum-based, tall oil-based, wood-based and other natural-based resins. Examples thereof include rosin derivatives obtained by subjecting rosin or natural rosin to hydrogenation, disproportionation, polymerization, maleation, esterification and the like. And, the addition amount of the tackifier in this case is 3 with respect to 100 parts by weight of the copolymer.
It is adjusted in the range of 50 parts by weight. Incidentally, if it is less than 3 parts by weight, the effect of improving the adhesive force of the obtained adhesive to the adherend is poor, while if it exceeds 50 parts by weight, the adhesive force of the obtained adhesive to the adherend becomes weak.

If necessary, a plasticizer, an antioxidant, an emulsifier, an antiseptic, a thickener, an antifoaming agent, a dispersant, etc. may be added to the pressure-sensitive adhesive as long as its action and effect are not impaired. Good. In particular, after the preparation of the adhesive, the relaxation elastic modulus at a temperature of 25 ° C. of the adhesive was 1.0 after being left at 70 ° C. for 48 hours.
A material having a pressure of × 10 ^{6 to} 1.0 × 10 ⁷ Pa is desirable.
Incidentally, when the relaxation elastic modulus is less than 1.0 × 10 ⁶ Pa, the pressure-sensitive adhesive becomes too soft, and the cohesive force is reduced, which may cause contamination of the adherend (adhesive residue). On the other hand, 1.0
If it exceeds × 10 ⁷ Pa, the adhesive cannot sufficiently wet the surface of the adherend, which may cause the label to float. The relaxation elastic modulus here is 1 Hz,
Measuring instrument PL-DMTA (POLYMER
LABORATORY).

The surface base material which is one of the constituents of the removable pressure-sensitive adhesive sheet is not particularly limited, but the removability, particularly the tearing of the top paper, is not limited to the paper layer of the surface base material constituting the removable pressure-sensitive adhesive sheet. Strength is related, in order to obtain the desired effect, the characteristics of the raw material pulp that constitutes the paper layer, the blending amount,
Alternatively, it can be achieved by adjusting the addition amount of the filler and the surface sizing agent.

In particular, as the surface base material, the pulp fibers satisfying the following formula are used in 25 of all the pulp fibers constituting the base paper.
% By weight or more, and the filler is 2 to the total pulp fiber content.
A base material obtained by applying a coating liquid consisting of at least starch and a synthetic sizing agent on the surface of a base paper containing 10% by weight and drying it does not cause tearing of the top paper when the label is peeled off. It can be a preferred embodiment as a surface base material having. 1.0 ≤ L ≤ 3.0 0.4 ≤ d / D ≤ 0.8 where L: J. TAPPI No. 52. Length-weighted average fiber length (mm) measured by the method according to 52. D: Average fiber diameter (μm) measured by micrograph d: Average lumen diameter (μ measured by micrograph)
m)

As the pulp fiber satisfying the above conditional expressions and, for example, softwood is used as a raw material and KP and S are used.
Chemical pulp obtained by the P or AP method and the like can be mentioned. Incidentally, in order to obtain the desired effect in the present invention,
It is desirable that the pulp fibers satisfying the above conditions are contained in an amount of 25% by weight or more of the total pulp fibers constituting the base paper. In addition, other wood pulp, non-wood pulp such as kenaf, bamboo, and hemp, synthetic pulp such as polyester and polyolefin, or synthetic fiber, and further glass, as long as the pulp fiber satisfying the above conditions is contained in an amount of 25% by weight or more. Inorganic fibers such as fibers and ceramic fibers can be appropriately used.

When the length-weighted average fiber length (hereinafter referred to as L value) of pulp fibers exceeds 3.0 mm, the dispersibility of the stock in the papermaking process becomes poor, and good formation cannot be obtained. If the thickness is less than 1.0 mm, the paper layer strength may be weakened. Therefore, the L value is 1.0 to 3.0 mm, more preferably 1.5.
It is desirable that the thickness is in the range of up to 2.5 mm. When the d / D ratio in the conditional expression exceeds 0.8, the paper is likely to be crushed and smoothness is improved, but the opacity is extremely decreased, and after the adhesive sheet is processed, the color of the adherend surface at the time of sticking, Patterns and the like tend to be transparent and lack concealing properties. On the other hand, when it is less than 0.4,
The fibers are too hard to crush the paper, the smoothness of the paper surface and the printing effect are inferior, and the strength of the paper layer may decrease. Therefore, the d / D ratio is preferably 0.4 to 0.8, more preferably 0.45 to 0.75.

Here, the pulp fiber length is measured by a sieving method (TAPPI STD T233).
hm−82) and the projection method for pulp fiber length (TAPPI ST
D T232hm-85), etc., but in the present invention, J. TAPPI
The method of measuring the length-weighted average fiber length by the method specified in No. 52 was adopted. Unlike the screening method and projection method, this method has high detection power and can automatically measure the fiber length distribution without being affected by fiber width, fiber wall thickness, fiber flexibility, etc. It has the feature. In the present invention, FS-1 manufactured by KAJAANI of Finland is used.
The pulp fiber length was measured using a 00 type machine.

The average fiber diameter and average lumen diameter were measured from micrographs. When taking a micrograph,
Pulp fibers were embedded in an acrylic resin and a thin section made with a microtome was used. 200 fibers were measured for each and the average value was obtained. In order to obtain a surface base material having excellent removability, the pulp fiber thus prepared is contained in an amount of 25% by weight or more, preferably 30% by weight or more, more preferably 40% by weight, based on the total pulp fibers constituting the base paper. It is desirable to contain the above. By the way, even when the pulp fiber is used, if the content is less than 25% by weight of the total pulp fiber, sufficient paper interlaminar strength cannot be obtained, and satisfactory re-peelability is obtained. It may run out.

Further, as the base paper of the surface base material constituting the pressure-sensitive adhesive sheet of the present invention, it is preferable that the filler is contained in an amount of 2 to 10% by weight, more preferably 4 to 6% by weight, based on the total pulp fiber content. Used. By the way, if it is less than 2% by weight, the smoothness of the paper surface is deteriorated, while if it exceeds 10% by weight, the entanglement of pulp fibers is hindered and the interlaminar strength of the paper is decreased, and a satisfactory removability is obtained. It may run out.

The filler to be added to the base paper is not particularly limited, but for example, talc, kaolin, clay,
Calcined kaolin, derami kaolin, ground calcium carbonate,
Light calcium carbonate, magnesium carbonate, titanium dioxide, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, magnesium sulfate, magnesium silicate, calcium sulfate, calcium silicate, white carbon, aluminosilicate, silica, sericite, Examples thereof include mineral fillers such as bentonite and smectite, organic synthetic fillers such as polystyrene resin fine particles, urea formalin resin fine particles, and hollow microparticles, and the fillers contained in waste paper, brokes, and the like can be recycled. Among these various fillers, a filler having an average particle size of 0.1 to 9 μm, more preferably 0.3 to 6 μm, is particularly preferably used because a paper having excellent smoothness can be obtained.

In addition to pulp fiber and filler as the main components, various anionic and nonionic properties that have been conventionally used in the paper stock are used as long as the desired effects of the present invention are not impaired.
Cationic or amphoteric retention improver, drainage improver,
An internal additive for papermaking, such as a paper strength enhancer or an internal sizing agent, is appropriately selected and used as necessary. For example, Al, Fe, S
Polyvalent metal compounds such as n and Zn (sulfate band, aluminum chloride, sodium aluminate, basic aluminum chloride,
Basic aluminum compounds such as basic polyaluminum hydroxide, water-soluble aluminum compounds such as alumina sol easily dispersible in water, ferrous sulfate, ferric chloride, etc., and various sizing agents (alkyl ketene dimer, alkenyl anhydrous amber) Acid, styrene-acrylic type, higher fatty acid type, petroleum resin type sizing agent, rosin type sizing agent) and various starches, polyacrylamide, urea resin, melamine resin, epoxy resin, polyamide resin, polyamide / polyamine resin, Examples thereof include polyethyleneimine, polyamine, vegetable gum, polyvinyl alcohol, latex, polyethylene oxide, dispersion of hydrophilic crosslinked polymer particles and derivatives or modified products thereof, and various compounds such as colloidal silica and bentonite. In addition, a papermaking internal additive such as a dye, a fluorescent whitening agent, a pH adjusting agent, a defoaming agent, a pitch control agent, and a slime control agent may be appropriately added depending on the purpose of the paper.

The papermaking method is not particularly limited. For example, an acidic papermaking method having a papermaking pH of about 4.5, an alkaline filler such as calcium carbonate as a main component,
The papermaking pH is set to a weak acidity of about 6 to a weak alkalinity of about 9,
All papermaking methods such as the so-called neutral papermaking method can be applied. As the paper machine, a Fourdrinier paper machine, a twin wire paper machine, a round wire paper machine, a Yankee paper machine, or the like can be used as appropriate and is not particularly limited.

In order to obtain a surface base material having further excellent removability, the surface of the raw paper, which is the surface base material obtained under the above conditions, contains starch as a main component and at least a synthetic sizing agent as an auxiliary agent. It is more preferable to apply the coating liquid. Examples of the starch coated on the surface of the base paper of the surface substrate include, for example, oxidatively modified starch, enzyme modified starch, cationized starch, acetylated starch, etherified starch, aldehydized starch, hydroxyethylated starch, phosphorylated starch, α Modified starch and the like can be mentioned. These starch coating liquids have a concentration of 5.0 to 15.0% by weight, preferably 6.0 to 10.0.
Those prepared in the range of weight% are preferably used.
By the way, if it is less than 5.0% by weight, it is difficult to obtain a sufficient effect on the improvement of the paper interlaminar strength, while if it exceeds 15.0% by weight, the so-called blocking phenomenon in which the paper surfaces are joined at the time of winding and making. Is likely to occur.

Examples of synthetic sizing agents include alkyl ketene dimer type, alkenyl succinic anhydride type, styrene-acrylic type, higher fatty acid type, petroleum resin type sizing agents and rosin type sizing agents. The amount added is 0.1 to 1.0% by weight, preferably 0.3 to 0.7% by weight, based on 100% by weight of the starch coating liquid. Incidentally, if it is less than 0.1% by weight, a sufficient effect cannot be obtained for improving the paper interlaminar strength, while if it exceeds 1.0% by weight, the effect is saturated for improving the paper interlaminar strength. However, there is little need in terms of economy.

The coating solution is coated using a known coating apparatus such as a two-roll or metering blade type size press, a gravure coater, a gate roll coater, a bill blade and a short dwell coater.
The coating amount is 3.0 to 8.0 g / m ^{2 on} both sides as a dry weight.
The degree is desirable. If necessary, smoothness may be imparted by a smoothing device such as a calender or a super calender.

The pressure-sensitive adhesive sheet of the present invention is obtained by combining the surface substrate thus obtained and the pressure-sensitive adhesive, and there is no unnecessary swelling at the time of sticking, and at the time of re-peeling, the top paper is torn or the adhesive remains on the adherend. It has excellent re-peelability without any problems. The method for forming the pressure-sensitive adhesive sheet is not particularly limited, and the pressure-sensitive adhesive layer is formed by coating the pressure-sensitive adhesive on the release agent layer surface of the release sheet according to a conventional method and drying the pressure-sensitive adhesive layer. It is finished by pasting the surface base material (back surface).

As the release sheet, high-density base paper such as glassine paper, clay-coated paper, kraft paper, or polylaminated paper obtained by laminating polyethylene or the like on high-quality paper is used. A release agent layer is formed by applying about 0.05 to ³ g / m ² and thermally curing, irradiating with ionizing radiation to cure, and the like. As the coating device in this case, for example, a multi-stage roll coater, an air knife coater, a bar coater, an offset gravure coater, a direct gravure coater, or the like is used. The pressure-sensitive adhesive is usually 3,000 to 8,000 by means of adjusting the molecular weight of acrylic acid ester, diluting with water or a solvent, or thickening.
The viscosity is adjusted to about 0 centipoise and the release sheet is coated. As the coating device in this case, for example, a reverse roll coater, a knife coater, an air knife coater, a bar coater, a slot die coater, a lip coater, a reverse gravure coater, or the like is used, and the coating amount is 5 to 50 g / dry weight. It is adjusted in the range of about m ² .

In the removable pressure-sensitive adhesive sheet of the present invention, if a subbing layer containing a pigment is provided between the surface substrate and the pressure-sensitive adhesive layer, the adhesive residue on the adherend can be further suppressed, which is preferable. This is one of the modes. As the pigment to be contained in the undercoat layer, an ordinary inorganic or organic pigment can be used, and examples thereof include oxides, hydroxides and sulfides of various metals such as magnesium, calcium, zinc, barium, titanium, aluminum, antimony and lead. Thing, carbonate, sulfate,
Alternatively, a silicate compound or fine solid polymer powder such as polystyrene, polyethylene, or polyvinyl chloride may be used. Among them, if an inorganic pigment such as kaolin, talc, silica, gypsum, barite powder, alumina white, gloss white, satin white, titanium oxide, calcium carbonate, acid clay, activated clay etc. is used, it becomes ionic with the adhesive layer. Interaction is added, and the anchoring effect is exerted more effectively. The amount of the pigment contained in the undercoat layer is preferably 90% by weight or less, more preferably 80% by weight or less based on the total solids constituting the undercoat layer. Incidentally, if it exceeds 90% by weight, the bonding force between the undercoat layer and the surface base material becomes insufficient, and the pigment may fall off.

In the undercoat layer, a binder is used as a material for fixing the pigments to each other or between the undercoat layer and the surface substrate. Examples of the binder include casein, dextrin, starch, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, Hydroxyethyl cellulose, polyvinyl alcohol, styrene / butadiene copolymer, methyl methacrylate / butadiene copolymer, ethylene / vinyl chloride copolymer, ethylene / vinylidene chloride copolymer, acrylic ester copolymer, ethylene / vinyl acetate copolymer A natural or synthetic resin binder such as coalesced is used in the form of an aqueous solution or an aqueous dispersion. In addition to the pigment, various auxiliary agents such as an antifoaming agent and a dispersant may be added to the undercoat layer depending on the purpose, as long as the properties thereof are not impaired.

Regarding the method of applying the coating liquid for the undercoat layer containing the pigment onto the surface substrate, it can be applied by a usual coating apparatus such as an air knife coater, a blade coater, a roll coater, a bar coater, Coating weight is 2 by dry weight
g / m ² or more, it is preferably adjusted in the range of 5 to 10 g / m ^2.

[0034]

The present invention will be described in more detail with reference to the following examples, but of course the present invention is not limited thereto. In addition, all parts, ratios, coating amounts, etc. in the examples are shown by weight of solid content unless otherwise specified.

Example 1 (Production of adhesive) 40 parts of water and 0.1 part of ammonium persulfate as a polymerization initiator were charged into an autoclave equipped with a stirrer, a temperature controller and a reflux condenser, and the temperature was raised to 70 ° C. did. Next, 100 parts of a monomer mixture consisting of acrylic acid: 1 part, 2-ethylhexyl acrylate: 95 parts and acrylonitrile: 4 parts, n-butyl mercaptan as a molecular weight regulator 0.05 part, water 60 parts, dodecylbenzene as an emulsifier. After adding 0.2 part of sodium sulfonate, the mixture was stirred and emulsified to prepare a pre-emulsion.

The whole amount of this pre-emulsion was continuously added to the autoclave over 8 hours, and the mixture was stirred at 80 ° C. to carry out emulsion polymerization. Then, stirring was further continued at 80 ° C. for 2 hours to complete the copolymerization. To 100 parts of the emulsion obtained by the above method, 0.5 part of a polyglycidyl compound (trade name: Denacol EX-421 / manufactured by Nagase Kasei Co., Ltd.) was added, and further to 100 parts by weight of the adhesive solid content. Then, by adding 15 parts by weight of a terpene phenol resin (trade name: Tamanor E-100 / manufactured by Arakawa Chemical Industry Co., Ltd., solid content concentration = 52.9%) and mixing,
An adhesive having a relaxation elastic modulus at 25 ° C. of 5.0 × 10 ⁶ Pa was obtained.

(Production of Surface Substrate) Pulp A [L value = 0.
67 mm, d / D ratio = 0.51, Canadian Standard Freeness (hereinafter referred to as CSF) 500 ml]
Pulp B satisfying 60 parts, conditional expression (L value = 1.9
0 mm, d / D ratio = 0.74, CSF 500 ml) 40
Part of pulp pulp is mixed with kaolin to reduce the paper ash content to 4
% So that rosin size as a sizing agent is 1.4% with respect to the absolutely dry pulp, and a sulfuric acid band is 2.0.
% Was added. This pulp slurry was paper-made using a fourdrinier cylinder dryer paper machine, and an oxidized starch having a concentration of 9% (trade name: SK-20 / Nippon Corn Starch Co., Ltd.)
Made in water, synthetic sizing agent (trade name: Hummer Coat S
-700 / Missawa Ceramic Chemical Co., Ltd.) 0.5
% Of the resulting coating liquid was applied by a size press to a dry weight of 5 g / m ² , dried and then treated with a 4-stage super calender to obtain a surface of 76.8 g / m ² . A substrate was manufactured.

(Preparation of pressure-sensitive adhesive sheet) Using the above-mentioned pressure-sensitive adhesive and the surface substrate, a commercially available polyethylene laminate release paper was separately coated with the above-mentioned pressure-sensitive adhesive so as to have a dry weight of 22 g / m ² . After drying, the pressure-sensitive adhesive layer surface and the back surface of the front surface substrate were attached to each other to obtain a pressure-sensitive adhesive sheet.

Example 2 In Example 1, the monomer composition of the pressure sensitive adhesive was changed to acrylic acid:
0.1 part, 2-ethylhexyl acrylate: 98 parts,
Acrylonitrile: A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the amount was changed to 1.9 parts.

Example 3 In Example 1, the adhesive composition was changed to acrylic acid:
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that 5 parts, 2-ethylhexyl acrylate: 75 parts, and acrylonitrile: 20 parts were changed.

Example 4 In Example 1, a terpene phenol resin (trade name: Tamanol E-100 /) was added to 100 parts of the adhesive solid content.
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the addition amount of Arakawa Chemical Industry Co., Ltd.) was changed to 5 parts.

Example 5 In Example 1, a polymerized rosin resin (trade name: Super Ester E-650 / Arakawa Chemical Industry Co., Ltd., solid content, instead of terpene phenol resin, was added to 100 parts solid content of the adhesive. A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that 15 parts (concentration = 50.0%) was added.

Example 6 In Example 1, an esterified rosin resin (trade name: Super Ester E-720 / manufactured by Arakawa Chemical Industry Co., Ltd., solid, instead of terpene phenol resin was used based on 100 parts of the solid content of the adhesive. A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that 15 parts of (concentration = 50.8%) was added.

Example 7 In Example 1, a terpene phenol resin (trade name: Tamanol E-100 /) was added to 100 parts of the solid content of the adhesive.
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the addition amount of Arakawa Chemical Industry Co., Ltd.) was changed to 42 parts.

Example 8 A surface base material was produced in the same manner as in Example 1 except that 80 parts of pulp A and 20 parts of pulp B were used as the pulp composition of the base paper of the surface base material, An adhesive sheet was obtained.

Example 9 In Example 1, a pigment subbing layer [main composition: Kaolin 100] was formed on the back surface of the same surface base material as used in Example 1.
Part (trade name: UW-90 / manufactured by EMC (USA)), 5 parts of oxidized starch (trade name: ace A / manufactured by Oji Corn Starch Co., Ltd.), 15 parts of styrene-butadiene copolymer latex (trade name: SN) -307 / Sumitomo Dow Co., Ltd.] was used in the same manner as in Example 1 except that a dry base material having a dry weight of 2 g / m ² was used as the surface substrate to obtain an adhesive sheet.

Comparative Example 1 A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the tackifier (terpene phenol resin) was not added.

Comparative Example 2 In Example 1, terpene phenol resin (trade name: Tamanol E-100 /) was added to 100 parts of the adhesive solid content.
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the addition amount of Arakawa Chemical Industry Co., Ltd.) was changed to 1.5 parts.

Comparative Example 3 In Example 1, 100 parts by weight of the solid content of the adhesive was used to prepare a terpene phenol resin (trade name: Tamanol E-100 /
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the addition amount of Arakawa Chemical Industry Co., Ltd.) was changed to 60 parts.

Comparative Example 4 In Example 1, a petroleum resin (trade name: K) was used instead of the terpene phenol resin with respect to 100 parts of the adhesive solid content.
An adhesive sheet was obtained in the same manner as in Example 1 except that 15 parts of E-756B / Arakawa Chemical Industries Co., Ltd.) was added.

Comparative Example 5 In Example 1, the adhesive composition was changed to acrylic acid:
0.01 part, 2-ethylhexyl acrylate: 90
Parts, acrylonitrile: 9.99 parts, and a pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that a pressure-sensitive adhesive having a relaxation elastic modulus at 25 ° C. of 1.0 × 10 ⁵ Pa was used.

Comparative Example 6 In Example 1, the adhesive composition was changed to acrylic acid:
In the same manner as in Example 1 except that 10 parts, 2-ethylhexyl acrylate: 85 parts, and acrylonitrile: 5 parts were used, and an adhesive having a relaxation elastic modulus at 25 ° C. of 1.0 × 10 ⁸ Pa was used. An adhesive sheet was obtained.

The adhesive sheet obtained as described above was subjected to the following evaluation tests, and the results obtained are summarized in Table 1.

(Evaluation Test Items) [Adhesive Strength] Adhesive strength to polyethylene laminated paper and a floppy disk was measured in accordance with the method for measuring the normal adhesive strength of JIS Z-0237. (Unit: g / 25m
m)

[Label Floating, Peeling] After the production of the pressure-sensitive adhesive sheet, it was stored for 7 days in an atmosphere of a temperature of 23 ± 2 ° C. and a relative humidity of 65 ± 5% to obtain a measurement sample. This adhesive sheet is 7 cm
Floppy disk (3.5 inches) with a 7 cm square cut, all corners removed, and the surface wiped with ethanol.
The sample was affixed to, and left for 1 day in a constant temperature bath at 70 ° C., then returned to room temperature and the label floated and peeled off according to the following evaluation criteria. A: Floating and no peeling. B: The corners on the back of the floppy disk are floating,
It has peeled off. C: Floating and peeling are severe, and it is difficult to use as it is. D: The entire folded portion is completely peeled off.

[Removability] The above-mentioned "label floating, peeling" was peeled off by hand from the wider side of the adhesive sheet, and the removability was evaluated according to the following evaluation criteria. ⊚: There is no adhesive residue or paper tear. ○: Almost no adhesive residue or paper breakage. Δ: There is some paper breakage and adhesive residue, but that part can be easily removed and there is no practical problem. X: Paper is severely torn and must be peeled off several times, or adhesive remains on the entire surface of the adherend, making it practically unusable.

[0057]

[Table 1]

[0058]

As is clear from Table 1, the removable pressure-sensitive adhesive sheet of the present invention was a removable pressure-sensitive adhesive sheet which did not have unnecessary floating when attached and had excellent removable property. .

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C09J 133/06 JDA 193/00 JAK

Claims (3)

[Claims] 1. A releasable pressure-sensitive adhesive sheet comprising at least a release sheet, a pressure-sensitive adhesive layer, and a surface base material laminated together,
The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer contains at least one rosin-based resin or terpene-based resin based on 100 parts by weight of the copolymer composed of the following monomers, the cross-linking agent, and the copolymer.
A re-peelable pressure-sensitive adhesive sheet, characterized in that 3 to 50 parts by weight of a tackifier composed of three is added. (A) an ethylenically unsaturated carboxylic acid-containing monomers: from 0.1 to 5 wt% (b) (meth) C ₄ -C ₁₀ alkyl ester monomers of acrylic acid: 65 to 98 wt% (c) These Other monomers copolymerizable with the above monomer: 1 to 30% by weight 2. The relaxation elastic modulus of the adhesive at 25 ° C. is 1.
The removable pressure-sensitive adhesive sheet according to claim 1, which has a viscosity of 0 × 10 ⁶ to 1.0 × 10 ⁷ Pa. 3. A base paper whose surface base material contains pulp fibers satisfying the following formula in an amount of 25% by weight or more based on the total pulp fibers and a filler in an amount of 2 to 10% by weight based on the total pulp fibers. The releasable pressure-sensitive adhesive sheet according to claim 1 or 2, which is obtained by applying a coating solution containing at least starch and a synthetic sizing agent to the surface of the coating solution and drying it. 1.0 ≤ L ≤ 3.0 0.4 ≤ d / D ≤ 0.8 where L: J. TAPPI No. 52. Length-weighted average fiber length (mm) measured by the method according to 52. D: Average fiber diameter (μm) measured by micrograph d: Average lumen diameter (μ measured by micrograph)
m)