JPH05295696A - Pressure-sensitive adhesive sheet - Google Patents

Abstract

PURPOSE:To obtain the subject sheet effective for stabilizing the peeling work of a masking sheet, enabling the high-speed bonding treatment and producible at a low cost by closely contacting a masking sheet with a transparent layer in a peelable state and applying a pressure-sensitive adhesive layer exhibiting adhesivity exclusively under strong pressure to the transparent layer of the obtained laminate. CONSTITUTION:A peelable masking sheet 7 is produced by coating the one surface of a double-coated paper with an electron-curable polyester acrylate resin, etc., containing a silicone as a releasing agent and curing the coating layer. A polyolefin dispersion liquid is applied to the resin layer to form a transparent layer 8. The transparent layer of the sheet is coated with an adhesive coating liquid produced by mixing an acrylate emulsion, pulp powder and synthetic silica to form a pressure-sensitive adhesive layer 9 exhibiting adhesivity exclusively under strong pressure. The objective pressure-sensitive adhesive sheet 6 produced by this process at a low cost is effective for highly stabilizing the peeling work of a masking sheet, enables the high-speed bonding treatment and is useful for the manufacture of a privacy postcard.

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 useful for manufacturing a confidential postcard, and more specifically, peeling off of the concealable sheet is extremely stable and the joining process can be performed at high speed. Moreover, the present invention relates to an inexpensive pressure-sensitive adhesive sheet.

[0002]

2. Description of the Related Art Confidential postcards of the type in which an adhesive label is attached to a portion on which personal information is placed and the information at that portion is concealed are in increasing demand due to the merit of being able to mail confidential information at a postcard fee. For this type of postcard,
Several types have already been put on the market, but none of them are still sufficient in terms of performance or cost. For example, those disclosed in Japanese Utility Model Application Laid-Open No. 63-6870 cannot be easily re-bonded once peeling occurs from a non-adhesive resin layer other than the adhesive layer which is the bonding surface and the label is once peeled from the postcard. It has a feature that the peeling of the label is extremely stable, but since such an adhesive label is provided with an adhesive layer that can be strongly bonded even at normal pressure like ordinary adhesive paper. In addition, a release paper for protecting the pressure-sensitive adhesive layer is required before sticking to a postcard, and the manufacturing cost is extremely high. Therefore, the cost merit due to the low shipping fee is small.

On the other hand, more recently, similar to the above, it has been attempted to use a heat-seal type adhesive layer having different adhesive and release surfaces for postcards. Since it does not require paper, the cost is low, but the method of joining by heat has a problem that the process of joining the label and the postcard cannot be speeded up.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pressure-sensitive adhesive sheet which is extremely stable in peeling off the concealable sheet, can carry out a joining process at high speed, and is inexpensive. ..

[0005]

As a result of earnest research, the present inventors have found that the above problems can be solved by providing a specific pressure-sensitive adhesive layer on a laminated sheet having a special layer structure, and completed the present invention. Came to do.

The present invention is a pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer having adhesiveness only under high pressure is provided on a transparent layer of a laminate in which a hiding sheet and a transparent layer are releasably adhered to each other. ..

[0007]

First, the case where the pressure-sensitive adhesive sheet of the present invention is used for a concealed postcard will be described in detail with reference to the drawings. FIG. 1 is a plan view showing a continuous sheet 1 for postcards, in which a non-adhesive sheet is subjected to base printing 4 for address fields, price fields, advertisements, etc. and perforation 2 and marginal 3 processing, and then a line printer, etc. It is obtained by outputting the personal information 5 such as the amount of money.

FIG. 2 is a plan view showing the pressure-sensitive adhesive sheet 6 of the present invention, and FIG. 3 is a sectional view taken along the line AA of the pressure-sensitive adhesive sheet of FIG. A continuous pressure-sensitive adhesive sheet in which an adhesive layer 9 having adhesiveness only under high pressure is provided on the transparent layer of the laminate in which the concealable sheet 7 and the transparent layer 8 are releasably adhered to each other, if necessary. It is obtained by performing underprinting on the front surface and / or the back surface of the sheet, and subsequently processing perforations 2 and marginal 3 and the like.

FIG. 4 is a plan view showing a form in which the pressure-sensitive adhesive continuous sheet of FIG. 2 is superposed on the postcard continuous sheet of FIG. In this state, it is guided into the general-purpose pressure sealing device using the marginal hole, and after the marginal and perforation are cut, the pressure is applied to form the concealed postcard 10 shown in the plan view of FIG. .. FIG. 6 shows B of the covert postcard 10 of FIG.
It is a sectional view taken along the line B. The confidential information is a concealed postcard which is covered with a concealable sheet and cannot be read.

FIG. 7 is a sectional view showing a state in which the concealable sheet 7 is peeled off from the concealed postcard 10 of FIG. 6, and personal information in the concealed portion can be seen through the transparent layer and the adhesive layer.

The concealable sheet used in the present invention may be of any property as long as it has a concealing property and can be peeled off from the adjacent transparent layer. Among them, a hiding sheet having releasability is preferably cited, for example, a support provided with a release agent layer, a release agent layer optionally added with a pigment and a colorant, A support laminated with a polyolefin such as polyethylene, a laminate containing a pigment, a release agent, and a colorant, if necessary, a water-soluble binder, an emulsion binder, an oil-soluble binder, and an ultraviolet ray. A curable resin, an electron beam curable resin or the like smeared using a coating machine or a printing machine and cured and dried, and if necessary, a pigment in the smear layer,
Release agent, dispersant, surfactant, coloring agent added,
Alternatively, those having extremely high releasability, such as those obtained by further coating a release agent on the laminate layer and the smearing layer, can be mentioned.

The support may be paper, non-woven fabric, synthetic paper,
A film, a metal foil, or the like having a hiding property or a film having a hiding property can be used, but paper is preferably used from the viewpoint of cost. Examples of the paper include high-quality paper, coated paper, art paper, cast coated paper, impregnated paper, metal evaporated paper, and the like, and those obtained by coloring or tint-printing the base material. The paper making method is not particularly limited, and recycled paper recycled pulp, synthetic pulp, etc. may be included. Incidentally, the hiding sheet is usually 30 to 20.
Those with a thickness in the range of 0 μm are used.

The transparent layer referred to in the present invention is a binder such as a water-soluble binder, an emulsion-based binder, an oil-soluble binder, an ultraviolet curable resin, an electron beam curable resin, etc., for example, by laminating a polyolefin on the above-mentioned concealable sheet. Alternatively, it can be obtained by smearing a release agent using a coating machine or a printing machine. Incidentally, a pigment, a colored dye, a release agent, etc. can be added to the binder layer within a range that does not extremely hinder the light transmission. Incidentally, the transparent layer is usually provided in the range of 1 to 60 g / m ² .

Examples of the release agent include silicone such as polydimethylsiloxane and polyphenylmethylsiloxane, fluorine compounds such as perfluoroalkyl phosphate ester, fluoroalkyl group-containing (meth) acrylate copolymer, higher fatty acid, and higher fatty acid. Waxes such as fatty acid metal salts, higher fatty acid amides, higher alcohols, polyethylene wax, and various paraffin waxes can be used.

Examples of the pigment include synthetic silica, colloidal silica, kaolin, clay, calcium carbonate, aluminum hydroxide, zinc oxide, titanium oxide, melamine resin particles, benzoguanamine resin particles and polyolefin particles.

Examples of the water-soluble binder include gelatin, albumin, casein, agar, gum arabic, sodium alginate, starch, oxidized starch, etherified starch, esterified starch, carboxymethyl cellulose, hydroxyethyl cellulose, polyvinyl alcohol, polyvinylpyrrolidone, Polyacrylic acid, polyacrylamide,
Examples thereof include ethylene-maleic anhydride copolymer, styrene-maleic anhydride copolymer, methyl vinyl ether-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer and the like.

Examples of emulsion binders include styrene-butadiene latex, acrylonitrile-butadiene latex, acrylic ester latex, vinyl acetate latex, vinylidene chloride latex, and carboxy-modified (eg acrylic acid-modified) latex thereof. Can be mentioned. Examples of the oil-soluble binder include rosin, copearl, damar, shellac, ethyl cellulose, hydroxypropyl cellulose, ethyl hydroxyethyl cellulose, acetyl cellulose, cellulose acetate propionate, cellulose acetate butyrate, nitrocellulose, polyvinyl butyral, polyvinyl chloride, poly Vinyl acetate, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, polystyrene, chlorinated polypropylene styrene resin, acrylic resin, phenol resin, xylene resin, urea resin, melamine resin, ketone resin, coumarone-
Examples thereof include indene resin, petroleum resin, terpene resin, cyclized rubber, chlorinated rubber, alkyd resin, polyamide resin, epoxy resin and polyurethane.

As the ultraviolet or electron beam curable resin,
For example, polyethylene glycol diacrylate, propylene glycol diacrylate, trimethylolpropane diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, hexanediol diacrylate, 1,2-butanediol diacrylate, and epoxy resin. Examples thereof include a reaction with acrylic acid, a reaction between maleic acid, pentaerythritol and acrylic acid, and a condensate of maleic acid, diethylene glycol and acrylic acid.

In the case of curing with ultraviolet rays, a photopolymerization initiator is added to the above compound, and a sensitizer is added if necessary. Examples of the photopolymerization initiator include benzoquinone, phenanthrenequinone, naphthoquinone, diisopropylphenanthrenequinone, benzoisobutyl ether, benzoin, furoin butyl ether, Michler's ketone, Michler's thioketone, fluorenone, trinitrofluorenone, β-benzoinaminonaphthalene. As the sensitizer, for example, triethanolamine, N-
Methyldiethanolamine, N, N-dimethylethanolamine, N-methylmorpholine and the like can be mentioned.

The present invention uses a laminated sheet prepared by selecting the above-mentioned materials and the like so that the concealable sheet and the transparent layer are separated from each other, and the pressure-sensitive adhesive layer having the adhesive property on the transparent layer under high pressure. Is a feature.

The term “adhesive layer having adhesiveness under high pressure” as used in the present invention means, specifically, ^two pressure-sensitive adhesive sheets obtained by providing an adhesive layer on a high-quality paper of 50 g / m ² When the adhesive layers are overlapped facing each other and bonded by applying a pressure of 1 kg / cm ² , the surfaces of the adhesive layers show a T-type peeling force of 10 g / 25 mm or less when measured based on JIS K 6833-1980, and 300
An adhesive layer composition is used in which the surfaces of the adhesive layers exhibit a T-type peeling force of 50 g / 25 mm or more when bonded by applying a pressure of kg / cm ² .

The pressure-sensitive adhesive sheet of the present invention, which is a combination of such an adhesive layer composition and the above-mentioned laminate, is sufficiently treated by applying a pressure of about 300 kg / cm ² to a portion of a postcard or the like to be concealed. It does not come off or come off. When the concealing sheet is peeled off to obtain information, it is peeled off from the joint surface between the concealing sheet and the transparent layer, and the original state cannot be restored. Further, since the information portion is protected by the adhesive layer and the transparent layer, there is no concern that the information will be tampered with. Further, since it exhibits almost no adhesiveness under a weak pressure, it does not require a release paper like an adhesive label.

The adhesive layer composition is usually formed by using an adhesive and an adhesion suppressant as basic components. Examples of the adhesive include ethylene-vinyl acetate-based resin, acrylic resin, vinyl chloride-based resin, vinylidene chloride-based resin, synthetic rubber-based resin, natural rubber-based resin, and the like, among which the glass transition point is -100 to The thing of 0 degreeC is preferable.

On the other hand, examples of the adhesion suppressant include pigments such as silica, kaolin, clay, calcium carbonate, aluminum hydroxide, zinc oxide, titanium oxide, melamine resin particles, benzoguanamine resin particles, polyolefin particles, starch particles and pulp powder. : The above-mentioned releasing agents and the like can be mentioned. By the way, the adhesion suppressant is usually 1 for the adhesive.
It is compounded in the range of 0 to 500% by weight.

Further, if necessary, the adhesive layer may further be water-soluble such as casein, agar, gum arabic, sodium alginate, starch, oxidized starch, esterified starch, carboxymethyl cellulose, hydroxyethyl cellulose, polyvinyl alcohol, polyvinylpyrrolidone and polyacrylic acid. Polymer, styrene-butadiene latex, latex such as acrylonitrile-butadiene latex, rosin resin and its derivatives, terpene resin, coumarone indene resin, xylene resin, alkylphenol resin, C
_{5 to} C ₉ petroleum resin and other tackifiers, adhesive-containing capsules and oil capsules for improving adhesiveness, antistatic agents, thickeners, dispersants, preservatives, antioxidants, defoamers, etc. Auxiliaries may be added.

The coating liquid used for forming the adhesive layer is
Although any of an aqueous system, an organic solvent system and a solventless system (hot melt, ionizing radiation) can be used, an aqueous coating solution in which the above adhesive is an emulsion is usually used.
The adhesive layer is usually coated with a coating liquid containing the above components using a coating machine such as an air knife coater, a blade coater, or a bar coater, or a printing machine such as gravure printing, screen printing, flexographic printing, letterpress printing, or offset printing. The coating is formed so that the dry weight is ² to 30 g / m ² .

The pressure-sensitive adhesive sheet thus obtained contains
Further, if necessary, printing (general information printing, tint block printing) on the front surface and / or back surface of the sheet, perforations, marginal and punching are appropriately selected and applied to form a label sheet, which is then wound. Taken or Z-folded.

On the other hand, examples of postcard sheets include high-quality paper, synthetic paper, impregnated paper, laminated paper, metallized paper, coated paper for printing (slightly coated paper, coated paper, art paper, cast coated paper). Etc.), coated paper for recording (heat-sensitive recording paper, pressure-sensitive copying paper,
Electrostatic recording paper, thermal transfer image-receiving paper, printing paper, ink jet recording paper, etc.) are used. The paper making method used for these is not particularly limited, and recycled paper recycled pulp, synthetic pulp and the like may be included.

If necessary, the postcard sheet may include a destination column,
The amount of money, background printing such as advertisement, processing such as perforation and marginal are appropriately selected and applied, and usually Z-folded. Subsequently, the personal information is recorded on a recording device such as a line printer.

Subsequently, the postcard sheet and the label sheet are guided and processed in the pressure sealing device while the recording surface of the postcard sheet and the adhesive surface of the label sheet are overlapped.

As the pressure-sealing device, a machine which is usually of a type in which a sheet is guided through a marginal hole and which is appropriately equipped with a portion capable of performing processing such as slitting, cutting, folding and pressing of the sheet is used. Note that the postcard sheet and the label sheet are not necessarily limited to those handled as continuous sheets, and may be handled as sheet sheets.

The pressure treatment is usually performed by using a pressure roll.
It is carried out under a pressure of ˜1000 kg / cm ² . At that time, it is more preferable that the sheet is equipped with a heating device because the adhesive force is stabilized by preheating the sheet to 30 to 60 ° C. The recording apparatus used in the present invention includes wet or dry electrophotographic method, thermal transfer method, thermal recording method, electrostatic recording method, electrolytic recording method, impact method, ink jet method, silver salt photography method and the like. used.

[0033]

EXAMPLES Examples of the present invention will be described below, but it goes without saying that the present invention is not limited to these examples. In the examples, "parts" means "parts by weight" and "%" means "% by weight" unless otherwise specified.

Example 1 (Preparation of Pressure-Sensitive Adhesive Sheet) A polyester acrylate electron beam curable resin containing silicon as a release agent was coated on one side of a double coated paper of 80 g / m ² with a coating amount of 8 g / m ^2.
A releasable concealing sheet was obtained by smearing and curing to a m ² .

Subsequently, a polyolefin dispersion liquid (trade name: Chemipearl W-500, manufactured by Mitsui Petrochemical Co., Ltd.) is formed on the resin layer.
Was smeared at a dry weight of 9 g / m ² to form a transparent layer.

Next, 100 parts (dry weight) of an acrylic ester emulsion (manufactured by Japan Synthetic Rubber, trade name: AE-923) and pulp powder (trade name: Avocell BE600).
/ 30, manufactured by Rittenmeyer) and 40 parts of synthetic silica (trade name: Mizukasil P-832, manufactured by Mizusawa Chemical Co., Ltd.) were mixed to adjust the solid content concentration to 30% to obtain an adhesive coating solution. , A dry weight of 10 g / m ² on the transparent layer of the above sheet
To obtain a pressure-sensitive adhesive sheet.

The surface (base paper surface) of the obtained pressure-sensitive adhesive sheet was subjected to underprinting and then perforated and marginal were inserted to obtain a roll-up sheet of a continuous label sheet (FIGS. 2 and 3).

(Preparation of continuous sheet for postcard) 145 g / m
Continuous printing for postcards by printing the underside on the front and back sides of ² high-quality paper, then inserting perforations and marginals, and outputting personal information such as address, name, data, etc. with an electrophotographic line printer (Fig. 1) To obtain a Z-folded sheet.

(Preparation of concealed postcard) The label continuous sheet was introduced into the pressure sealing device while being superimposed on the above postcard continuous sheet as shown in FIG. 4, and then pre-bonded first, followed by marginal and perforated lines. Is cut, and further 500kg / cm
The pressure was increased by ² to obtain a concealed postcard (FIG. 5: plan view, FIG. 6: cross-sectional view).

The concealable sheet of the concealed postcard thus obtained was peeled off to obtain a postcard shown in the sectional view of FIG.

[0041]

When the pressure-sensitive adhesive sheet of the present invention is processed into a concealed postcard, a postcard with extremely stable peeling can be obtained. In addition, the joining process can be performed at high speed. The concealment is extremely high and it cannot be tampered with. Furthermore, since it is cheap, it is extremely useful not only for postcards but also for confidential information.

[Brief description of drawings]

FIG. 1 is a plan view showing an example of a non-adhesive continuous sheet for postcards.

FIG. 2 is a plan view showing an example of a continuous label sheet which is a pressure-sensitive adhesive sheet.

FIG. 3 is a sectional view taken along line AA of the continuous label sheet of FIG.

4 shows a state in which the label sheet of FIG. 2 is superposed on the postcard sheet of FIG.

5 is an example of a concealed postcard of the present invention, which is obtained by guiding the stacked sheets of FIG. 4 into a general-purpose pressure sealing device, cutting marginal and perforated lines, and then applying pressure. ..

6 is a cross-sectional view taken along the line BB of the postcard of FIG.

FIG. 7 is a cross-sectional view showing a state where the label is peeled off from the postcard of FIG.

FIG. 8 is a cross-sectional view showing another example of a continuous label sheet that is a pressure-sensitive adhesive sheet.

9 is a cross-sectional view of a concealed postcard obtained by using the continuous label sheet of FIG.

FIG. 10 is a cross-sectional view showing another example of the continuous label sheet which is a pressure-sensitive adhesive sheet.

11 is a sectional view of a concealed postcard obtained by using the continuous label sheet of FIG.

[Explanation of symbols]

 1: Continuous sheet for postcards 2: Perforations 3: Marginal holes 4: Personal information (address / name) 5: Personal information (data) 6: Pressure-sensitive adhesive sheet (continuous sheet for labels) 7: Concealment sheet 8: Transparent layer 9: Pressure-sensitive adhesive layer 10: Concealed postcard 11: Postcard 12: Pressure-sensitive adhesive sheet (label) 13: Peeling point 14: Peeled postcard 15: Opaque support 16: Colored peelable layer 17: Colored or Ground pattern layer 18: Release layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication B42D 15/02 501 B 7008-2C 15/04 E 7008-2C 15/08 D 7008-2C C09J 7 / 02 JLJ 6770-4J D21H 27/30 G09F 3/02 C 7028-5G 3/03 E 7028-5G 3/10 B 7028-5G

Claims (2)

[Claims] 1. A pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer having adhesiveness only under high pressure is provided on a transparent layer of a laminate in which a hiding sheet and a transparent layer are releasably adhered to each other. 2. The pressure-sensitive adhesive sheet according to claim 1, wherein the masking sheet is a masking sheet having a releasing property.