JP2000219857A - Pressure-sensitive adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively obtain a pressure-sensitive adhesive sheet which gives little blotting, has excellent suitability for ink-jet printers and water- resistance, and satisfies adhesiveness and peelability for the paper for peelable post cards by incorporating an amphoteric ion latex into an adhesive layer. SOLUTION: This sheet is obtained by incorporating an adhesive and an adhesiveness-controlling agent on at least one side of a base sheet, and incorporating an amphoteric ion latex into the adhesive layer of a pressure-sensitive sheet which allows adhesion by the high-pressure treatment with adhesive layers being opposed, and the adhered face is peelable. The content of the amphoteric ion latex is preferably 1-40 wt.% per solid weight of the adhesive layer. In addition, it is preferable that the adhesive which constitutes the adhesive layer is a cation-modified natural rubber, and that polyvinyl alcohol is also used in the adhesive layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive sheet used for various systems such as postcards and cards having confidentiality.

[0002]

2. Description of the Related Art In recent years, in accordance with the revision of the Postal Code, a sheet on which necessary information is recorded is folded in two or three.
Postcard systems with confidentiality have been commercialized and spread.
Postcards having such confidentiality usually have no adhesiveness on one side of the base sheet, exhibit adhesiveness by pressing the adhesive layers in a state where they face each other, and re-peel after adhesion. A pressure-sensitive adhesive sheet (also referred to as confidential postcard paper) having an adhesive layer that can be used is used.

Normally, a pressure-sensitive adhesive sheet is printed as a postcard with fixed-form items printed thereon, and information such as personal information that is to be kept secret is printed on the adhesive layer surface, destinations and the like are printed on other parts by a printer or the like, and then dried with a dry sealer or the like. The confidential information is layered under pressure so that it cannot be seen from the outside. The confidential postcard is a postcard in which the recipient can obtain information by peeling off from the adhesive layer, and once the adhesive is peeled off, the adhesive surface has no adhesiveness, so that the postcard is not in a state before peeling.

[0004] Initially, postcard systems that maintain confidentiality were printed on confidential postcard paper, printed with a high-speed laser printer, pressed with a dry sealer, and shipped by a relatively large printing company. In recent years, the printing method has been changing from a high-speed laser printer method to a high-speed ink jet printer method provided with drying equipment capable of processing a large amount.

[0005] In the ink-jet system, fine droplets of ink are made to fly by various recording systems and adhere to a recording sheet such as paper to record images, characters, and the like. Normal,
The recording sheet has a high density of print dots, a bright and vivid color tone, no color sinking, ink absorption is fast, and even when print dots overlap, ink does not flow out or bleed, Low lateral diffusion is required.

Since a high-speed ink jet printer uses an anionic dye ink, when printing on ordinary confidential postcard paper, the ink has no water resistance and runs off due to water. Therefore, in order to make confidential postcard paper compatible with inkjet, an undercoat layer of a cationic compound is provided between the base sheet and the adhesive layer, the adhesive layer contains cationic colloidal silica, and the cationic compound is contained. Although studies have been made on such measures, it has been difficult to impart inkjet recording suitability while maintaining the function of the adhesive layer.

It was thought that the problem was solved by changing the recording ink to a water-resistant pigment-based ink. However, the pigment-based ink had poor fluidity when printing at high speed, and was inferior to the dye-based ink. Since it is relatively easy to dry, there has been a problem that nozzle clogging frequently occurs. As a countermeasure, printing is performed at a line speed of about 1/3 to 1/4 as compared with the dye system, and at present, the performance of the high-speed inkjet printer is not sufficiently exhibited.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the bleeding of the ink and to make it suitable for an ink jet printer.
An object of the present invention is to provide an inexpensive pressure-sensitive adhesive sheet having excellent water resistance and satisfying adhesiveness and removability as a confidential postcard.

[0009]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, by including amphoteric ion latex in the adhesive layer,
A pressure-sensitive adhesive sheet having both ink jet suitability and water resistance was obtained. Further, the present inventors have found that when an anionic component is removed from the components of the adhesive layer in order to further enhance the inkjet suitability, there is a problem that the adhesion between the base sheet and the adhesive layer is deteriorated. However, they have found that the adhesion can be drastically improved by incorporating an amphoteric ion latex into the adhesive layer, and have reached the present invention.

The present invention has an adhesive layer containing an adhesive and an adhesion control agent on at least one surface of a substrate sheet, and the adhesive layer is subjected to high pressure with the adhesive layers facing each other. A pressure-sensitive adhesive sheet that can be adhered by treatment and whose adhesive surface is peelable, wherein the adhesive layer contains amphoteric ion latex.

The amphoteric ionic latex preferably contains 1 to 40% by weight of the solid content of the adhesive layer.
Further, it is preferable that the adhesive constituting the adhesive layer is a cation-modified natural rubber because the ink jet recording suitability is further excellent. Furthermore, it is more preferable to use polyvinyl alcohol in combination with the adhesive layer because the adhesiveness between the adhesive layer and the base material is further excellent.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The pressure-sensitive adhesive sheet according to the present invention comprises an adhesive layer provided on at least one surface of a base sheet,
In a normal (before high pressure) state, it does not show adhesiveness, and
Adhesion can be performed by performing high pressure treatment with the adhesive layers facing each other, and the adhesive surface has an adhesive layer that can be removed again. That is, a configuration in which an adhesive layer having removability (hereinafter, referred to as a re-peelable surface) is formed only on one surface of the base sheet, and a configuration in which an adhesive layer having re-peelability (removable surface) is formed on both surfaces. And a configuration in which a removable adhesive layer (removable surface) is provided on one surface and a non-removable surface (hereinafter referred to as a permanent surface) is provided on the other surface.

The re-peelable surface and the permanent surface do not exhibit adhesiveness in a normal state, and are adhered by laminating under pressure with a dry sealer or the like. The adhesive strength is adjusted by adjusting the amount of the control agent. For example, on the re-peelable surface, after providing information that requires confidentiality, fold the sheet so that the information is hidden, or overlap another sheet, so that the re-peelable adhesive layers face each other. By performing the high pressure processing, a laminated sheet (for example, a postcard, a lottery, etc.) having information inside is obtained.

The adhesive used in the present invention is a natural rubber,
Examples include modified natural rubber, synthetic rubber such as styrene-butadiene rubber and acrylonitrile-butadiene rubber, ethylene-vinyl acetate copolymer resin, acrylate resin, vinyl chloride resin, vinylidene chloride resin, and the like. In particular, from the viewpoint of ink jet recording suitability, an adhesive containing no anionic component or a cationic adhesive is preferable.

Examples of the cationic adhesive include an adhesive obtained by cationizing an acrylic monomer such as methyl methacrylate to natural rubber during graft polymerization, and an adhesive obtained by cationizing a styrene-butadiene rubber or an acrylic resin during synthesis. However, it is preferable to use it alone or in combination with another resin. Among them, those obtained by cationizing an acrylic monomer such as methyl methacrylate to natural rubber during graft polymerization are water resistance of printing, heat resistance,
It is suitable from the point of friction resistance.

Examples of the cationic compound used for synthesizing the cationic adhesive include compounds having a quaternary ammonium group such as vinylbenzyltrimethylammonium chloride and lauryltrimethylammonium chloride, dimethylamine, diethylamine and methyl. Compounds having a secondary amino group such as ethylamine are exemplified. Among them, a compound having a quaternary ammonium group is preferable from the viewpoint of the stability of the paint.

The amount of the adhesive in the adhesive layer on the removable surface is preferably such that the solid content is 20 to 60% by weight. If the amount is less than 20% by weight, the strength of the adhesive layer will be weak, and if it exceeds 60% by weight, the pigment on the surface of the adhesive layer will be covered, the ink absorbency will be reduced, and the suitability for ink jet will be reduced. The amount of the adhesive in the adhesive layer on the permanent surface is such that the solid content is about 40 to 70% by weight. By the way, when the content is less than 40% by weight, removability is exhibited, and when the content exceeds 70% by weight, blocking tends to occur.

As the adhesion controlling agent, inorganic and organic pigments can be used. Examples include zinc oxide, titanium oxide, zeolite, calcium carbonate, clay, aluminum oxide, wheat starch, silica, alumina, colloidal silica, plastic pigment, polyethylene resin, polypropylene resin, and fluorine-based resin. Among them, wheat starch, silica and the like are suitable for controlling the adhesive and are preferably used. Also, wheat starch is used as a spacer to prevent blocking. Silica is preferable because it has excellent ink receptivity and improves printability and inkjet recording suitability. Fluorine-based resins are highly effective in preventing ink bleeding. Further, titanium oxide has a high hiding effect, and the hiding effect is further enhanced by mixing with silica. It is preferable that such an inorganic or organic pigment is used in combination as the adhesion control agent. The inorganic or organic pigment having a particle size of about 10 to 50 μm is used.

The present invention is characterized in that an amphoteric ion latex is contained in an adhesive layer containing the above-mentioned adhesive and the adhesive strength control agent and forming a removable surface. For example, the amphoteric ion latex has a core-shell composite structure shown in FIG. That is, the same particle surface has cationic and anionic functional groups, the quaternary alkylamine group has a higher density than the carboxyl group, and has excellent mechanical stability, and has a cationic colloid equivalent value on average. Zwitterionic latex can be exemplified.

The zwitterionic latex will be further described as follows. That is, a synthetic rubber latex or a synthetic resin emulsion modified with a carboxyl group is used as a seed latex, and the seed latex is neutralized to adjust the pH to 6.
After the above, a monomer represented by the following general formula (Chemical Formula 1) or a general formula (Chemical Formula 1)
When adding a mixture with an ethylenically unsaturated monomer copolymerizable with a monomer, the monomer is added so as to have an equivalent value larger than at least the colloid equivalent value (absolute value) of the seed latex, and a radical polymerization initiator is further added. To neutralize the polymer obtained by polymerizing the seed latex and the added monomer with an acid or salt, or
Grading agents (eg, alkyl halides, dimethyl sulfate,
General alkylating agent such as diethyl sulfate) and add 4
A latex having a cationic and anionic amphoteric functional group obtained by quaternary ammonium chloride,
This is a polymer emulsion in which high-density cationic properties are imparted to the emulsion particle surfaces.

[0021]

Embedded image

(Where R ₁ is H or CH ₃ , R ₂
Represents an alkylene group having 2 to 5 carbon atoms, R ₃ and R ₄ represent H or an alkyl group having 1 to 5 carbon atoms, A represents —CO—O— or —CO—NH—, and R ₂ , R ₃ , R ₄ is selected in a range where the monomer is hardly soluble or insoluble in water. )

Here, the colloid equivalent value is a value obtained by the following method. That is, 95 ml of distilled water is placed in a beaker, 5 ml of a 1000 ppm solution of a sample is added thereto, the pH is adjusted to 4 with 1% HCl, and the mixture is stirred for about 1 minute. Next, add toluidine blue indicator solution
Add 3 drops and titrate with N / 400 PVSK (polyvinyl potassium sulfate). The titration rate is 2 ml per minute,
The point at which the sample changes color from blue to red and the state is maintained for 10 seconds or more is defined as the end point of the reaction. In addition, the colloid equivalent value was calculated by the following equation (Equation 1).

[0024]

(Equation 1)

(Note: F is a sample-specific factor)

The reason why the monomer represented by the general formula (Chemical Formula 1) is preferably used is that the monomer itself is hardly soluble or insoluble in water, so that cation dissociation during polymerization is suppressed, and Is stable, and the polymer formed to have an amino group in its structural formula is neutralized with an acid or a salt, or is quaternized with a quaternizing agent.
It is easy to form a secondary ammonium salt, thereby giving a high-density cationic property to the latex particle surface.

Incidentally, specific examples of the monomer represented by the general formula (Formula 1) include, for example, diethylaminoethyl (meth) acrylate, dipropylaminoethyl (meth) acrylate, dibutylaminoethyl (meth) acrylate, t-dibutyl Aminoethyl (meth) acrylate,
Diethylaminopropyl (meth) acrylamide, dipropylaminopropyl (meth) acrylamide, dibutylaminopropyl (meth) acrylamide and the like can be mentioned.

Further, other ethylenically unsaturated monomers copolymerizable with the monomer represented by the general formula (Formula 1) include, for example, hydrophobic monomers such as (meth) acrylate, acrylonitrile, styrene, and vinyl acetate; Crosslinkable monomers such as N, N'-methylenebis (meth) acrylamide, diallyl phthalate, divinylbenzene, and (poly) ethylene glycol di (meth) acrylate. The ethylenically unsaturated monomer copolymerizable with the general formula (Chemical Formula 1) may be appropriately determined according to the glass transition temperature and physical properties of the target latex. On the other hand, it is adjusted at about 0 to 40% by weight.

In the present invention, the effect of improving the water resistance and the effect of improving the absorbability of the aqueous ink can be exhibited by incorporating such an amphoteric ion latex into the adhesive layer. Although the reason why such an excellent effect is obtained is not necessarily clear, it is probably that the zwitterionic latex used in the present invention has a cationic quaternary alkylamine group to improve the ink fixing effect, Further, it is considered that an electric interaction occurs between the latex particles due to the action of the amphoteric functional groups of the cation and the anion, and as a result, the generated fine pores contribute to the improvement of the ink absorbency.

When the anionic component is removed from the adhesive composition in order to enhance the suitability for ink jet, the adhesion between the base sheet and the adhesive layer is deteriorated. It is possible to improve the adhesiveness. This is presumably because the amphoteric ionic latex has good miscibility with various pigments and exhibits strong adhesion to the pigment, so that the adhesiveness of the formed adhesive layer can be improved.

Further, when the coating liquid for an adhesive layer contains a zwitterionic latex, it has little action as a surfactant and has a relatively low foaming property and is stable in a wide pH range.
Preparation of the coating liquid is facilitated, for example, it has good compatibility with the cationic polymer and does not cause solvent shock.

The amount of the amphoteric ionic latex in the present invention is preferably 1 to 40% by weight, more preferably 1 to 30% by weight of the solid content of the adhesive layer. By the way, if the amount is less than 1% by weight, the water resistance and the ink absorption are not sufficient, and the adhesion between the support and the adhesive layer is insufficient.
This causes problems such as powder dropping. If the amount exceeds 40% by weight, the adhesiveness during the pressure treatment is reduced, the function as a pressure-sensitive adhesive sheet is impaired, and the water resistance of printing tends to be poor.

In the case of a three-fold postcard (also referred to as a three-fold postcard), the adhesive layer on the permanent surface may also form the postcard surface. It is preferable to add a compound having the following formula to impart inkjet recording suitability.

Further, it is preferable to mix a water-soluble polymer such as polyvinyl alcohol in the adhesive layer, since the adhesion between the adhesive layer and the base material is improved. When a water-soluble polymer is blended, the content is preferably 10% by weight or less of the solid content of the adhesive layer. If the content exceeds 10% by weight, the viscosity of the coating liquid increases and the adhesiveness decreases, which is not preferable. In the adhesive layer, a pigment dispersant, a thickener,
Flow improvers, defoamers, foam inhibitors, release agents, foaming agents, penetrants, coloring dyes, ultraviolet absorbers, antistatic agents, cationic, nonionic or amphoteric surfactants, antioxidants,
Preservatives, water-proofing agents and the like can be added in appropriate amounts.

The base sheet is not particularly limited, but papers such as high quality paper, medium quality paper, art paper, coated paper, etc.
Synthetic paper, synthetic resin film, metal foil, non-woven fabric, etc. may be used, and these may be laminated or surface-treated. Among them, papers are preferably used because they are inexpensive. Of course, the papers may contain waste paper pulp, and the papermaking method is not particularly limited.

When coating the surface, the coating method is not particularly limited, but various blade coaters, roll coaters, air knife coaters, bar coaters, gravure coaters, die coaters, curtain coaters and the like are used. In the present invention, an air knife coater, a bar coater, a gravure coater and the like are preferable. The coating amount is in the range of ^{2 to} 30 g / m ² , preferably in the range of ^{3 to} 15 g / m ² .

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples. “Parts” and “%” shown in Examples are parts by weight and% by weight unless otherwise specified.

Example 1 [Formation of Removable Adhesive Layer] 81.3 g / m of high quality paper
^{2 On} one side of (OKH70, manufactured by Oji Paper Co., Ltd.), apply a paint for re-peelable
It was coated at 0 g / m ² and dried at a temperature of 100 ° C. for 1 minute by a hot air drier. "Coating composition for removable surface" ・ Cation-modified natural rubber-based latex (Frutite FB-3001, manufactured by Mitsui Fuller Co., Ltd.) 40 parts by weight ・ SBR-based amphoteric ion latex (Acostar C177, manufactured by Mitsui Cytec Co., Ltd.) 20 weight Parts: Wheat starch (AS-225, manufactured by Chiba Starch Co., Ltd.) 10 parts by weight-Precipitable synthetic silica (Mizukasil P-527, manufactured by Mizusawa Chemical Industry Co., Ltd.) 29 parts by weight-Auxiliary agent 1 part by weight

[Formation of Permanent Adhesive Adhesive Layer] On the opposite side of the high-quality paper coated with the above-mentioned re-peelable surface paint, a permanent-surface paint having the following composition was applied with a Meyer bar at 10 g / m ² per solid.
It was coated and dried for 1 minute at a temperature of 100 ° C. with a hot air drier to obtain a pressure-sensitive adhesive sheet (confidential postcard paper for tri-fold postcards). "Containing paint for permanent surface" ・ Cation-modified natural rubber-based latex (Frutite FB-3001, manufactured by Mitsui Fuller Co., Ltd.) 70 parts by weight ・ SBR-based zwitterionic latex (Acoster C177, manufactured by Mitsui Cytec Co., Ltd.) 3 parts by weight・ Wheat starch (AS-225, manufactured by Chiba Starch Co., Ltd.) 11 parts by weight ・ Precipitable synthetic silica (Mizukasil P-527, manufactured by Mizusawa Chemical Industry Co., Ltd.) 15 parts by weight ・ Auxiliary agent 1 part by weight

Example 2 The amount of the SBR zwitterionic latex on the removable surface was adjusted to 3
A pressure-sensitive adhesive sheet (confidential postcard for tri-fold postcard) was obtained in the same manner as in Example 1 except that the weight was changed to 5 parts by weight.

Example 3 A pressure-sensitive adhesive sheet (a confidential postcard for tri-fold postcard) was obtained in the same manner as in Example 1 except that the paint for the re-peelable surface was prepared as follows. "Coating composition for removable surface" ・ Cation-modified natural rubber-based latex (Frutite FB-3001, manufactured by Mitsui Fuller Co., Ltd.) 25 parts by weight ・ SBR-based amphoteric ion latex (Acostar C177, manufactured by Mitsui Cytec Co., Ltd.) 45 parts by weight Parts: Wheat starch (AS-225, manufactured by Chiba Starch Co., Ltd.) 10 parts by weight-Precipitable synthetic silica (Mizukasil P-527, manufactured by Mizusawa Chemical Industry Co., Ltd.) 29 parts by weight-Auxiliary agent 1 part by weight

Example 4 A pressure-sensitive adhesive sheet (a confidential postcard for three-fold postcard) was obtained in the same manner as in Example 1 except that the paint for the re-peelable surface was prepared as follows. "Coating composition for removable surface" ・ Cation-modified natural rubber-based latex (Frutite FB-3001, manufactured by Mitsui Fuller Co., Ltd.) 40 parts by weight ・ SBR-based amphoteric ion latex (Acostar C177, manufactured by Mitsui Cytec Co., Ltd.) 15 parts by weight Parts: Wheat starch (AS-225, manufactured by Chiba Starch Co., Ltd.) 10 parts by weight-Precipitable synthetic silica (Mizukasil P-527, manufactured by Mizusawa Chemical Industry Co., Ltd.) 29 parts by weight-Polyvinyl alcohol (PVA-105, Kuraray) 5 parts by weight ・ Aid 1 part by weight

Example 5 A pressure-sensitive adhesive sheet (a confidential postcard for tri-fold postcards) was obtained in the same manner as in Example 1 except that the paint for the re-peelable surface had the following composition. "Recoatable paint formulation"-Acrylic-modified natural rubber-based latex (Frutite FB-DO-3, manufactured by Mitsui Fuller Co., Ltd.) 35 parts by weight-SBR-based amphoteric ion latex (Acostar C177, manufactured by Mitsui Cytec Co., Ltd.) 20 parts by weight ・ Wheat starch (AS-225, manufactured by Chiba Starch Co., Ltd.) 10 parts by weight ・ Precipitable synthetic silica (Mizukasil P-527, manufactured by Mizusawa Chemical Industry Co., Ltd.) 29 parts by weight ・ Polyvinyl alcohol (PVA-105) , Kuraray Co., Ltd.) 5 parts by weight ・ Aids 1 part by weight

Comparative Example 1 A pressure-sensitive adhesive sheet (a confidential postcard for tri-fold postcard) was obtained in the same manner as in Example 1 except that the amount of the SBR zwitterionic latex on the re-peelable surface was not used.

Comparative Example 2 An SBR latex (Polylac 750K-10) was used as an anionic SBR type amphoteric ion latex on the re-peelable surface.
(Mitsui Chemicals Co., Ltd.) except that the paint for the removable surface was prepared in the same manner as in Example 1, but the paint was agglomerated and a pressure-sensitive adhesive sheet was not obtained.

Comparative Example 3 A pressure-sensitive adhesive sheet (a confidential postcard for tri-fold postcards) was obtained in the same manner as in Example 1 except that the paint for the re-peelable surface had the following composition. "Recoatable paint formulation"-Acrylic-modified natural rubber-based latex (Frutite FB-DO-3, manufactured by Mitsui Fuller Co., Ltd.) 40 parts by weight-Anionic SBR-based latex (Nipol LX416, manufactured by Nippon Zeon Co., Ltd.) 15 parts by weight-Wheat starch (AS-225, manufactured by Chiba Starch Co., Ltd.) 10 parts by weight-Precipitated synthetic silica (Mizukasil P-527, manufactured by Mizusawa Chemical Industry Co., Ltd.) 29 parts by weight-Water-soluble polymer (PVA) -105, Kuraray Co., Ltd.) 5 parts by weight ・ Auxiliary agent 1 part by weight

"Evaluation Method" (1) Adhesion of Adhesive Layer to Substrate Sheet The adhesive layer was rubbed with a finger, and the adhesion to the substrate sheet was visually evaluated. A: The adhesive layer does not peel off. ：: The adhesive layer is slightly peeled off, but at a level that does not cause any problem in practical use. X: This is a level at which the adhesive layer is peeled off and poses a practical problem.

(2) Water resistance of printing Yellow, magenta, cyan, and black were printed on the removable surface using an ink jet printer MC-830 (manufactured by Epson Corporation), and the ink was dipped in water for 2 minutes. Bleeding was evaluated visually. ◎: Excellent ○: No problem △: Slight, but no practical problem ×: Poor

(3) Adhesiveness of Removable Surface Using a dry sealer (manufactured by Toppan Forms Co., Ltd.), the obtained tri-fold postcard sample is cut into an appropriate size so that the removable surfaces are opposed to each other. Z-fold to 23
After conditioning for 24 hours at 65 ° C. and a temperature and humidity condition of 65%, the paper was passed through a press roll having a roll gap of 150 μm and pressed to form a confidential postcard. The obtained confidential postcard was peeled again by T-type peeling, and the peeled state and the state of the peeled surface were evaluated. ：: Re-peeled neatly ○: Re-peeled, but adhesive strength is slightly weak, but no problem in practical use △: Re-peeled, but weak in adhesive strength or partial substrate breakage, but no practical problem ×: Destruction of the substrate or peeling with low adhesive strength, a level that poses a practical problem

(4) Comprehensive Evaluation Comprehensive evaluation as confidential postcard paper was performed. ：: Very good as confidential postcard paper. ：: Excellent as confidential postcard paper. Δ: This is a level that has some problems as confidential postcard paper but has no practical problem. ×: There is a problem as confidential postcard paper, and it is at a level that cannot be used practically. XX: No pressure-sensitive adhesive sheet was obtained.

[0051]

[Table 1]

[0052]

According to the pressure-sensitive adhesive sheet provided with the base material sheet and the adhesive layer on at least one surface of the present invention, the adhesive layer contains an amphoteric ion latex so that the bleeding of the ink is reduced and the ink jet printing is carried out. A pressure-sensitive adhesive sheet that is excellent in printer suitability and water resistance, and that satisfies the adhesion and removability of confidential postcard paper is obtained.

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[Procedure amendment]

[Submission Date] May 6, 1999 (1999.5.6)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Added

[Correction contents]

[Brief description of the drawings]

FIG. 1 is a schematic structural view of a zwitterionic latex used in the present invention.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (Reference) C09J 133/00 C09J 133/00 F term (Reference) 2C005 WA03 4F100 AA20H AJ07 AJ07G AK25 AK25G AK68B AK68C AK73 AK73G AL06B AL06C AL06G AN01B AN01G AT00A BA02 BA03 BA07 BA10B BA10C DG10 EH46 GB90 JB07 JL13 JL13B JL13C JL14 JL14B JL14C JM01B JM01C JM01G YY00B YY00C 4J04 AA02 AA04 AA05 AA08 AA1 CA02 CA01 CA01 CA02 JA03 JB09 LA06 LA07 MA09 MB03 NA05 NA10

Claims (4)

[Claims] An adhesive layer containing an adhesive and an adhesion control agent is provided on at least one surface of a base sheet, and the adhesive layer is subjected to a high pressure treatment with the adhesive layers facing each other. A pressure-sensitive adhesive sheet whose adhesive surface can be peeled off, wherein the adhesive layer contains an amphoteric ion latex in the adhesive layer. 2. The pressure-sensitive adhesive sheet according to claim 1, wherein the zwitterionic latex contains 1 to 40% by weight of the solid content of the adhesive layer. 3. The pressure-sensitive adhesive sheet according to claim 1, wherein the adhesive constituting the adhesive layer is a cation-modified natural rubber. 4. The pressure-sensitive adhesive sheet according to claim 1, wherein the adhesive layer further contains polyvinyl alcohol.