JPH0655836A - Pressure sensitive recording sheet - Google Patents

Abstract

PURPOSE:To make bonding strength in preservation at high temperature invariable by a method wherein a pressure sensitive recording layer containing a color coupler and a developer which are contained in a microcapsule, an electron beam setting resin layer containing a radical polymerization inhibitor, etc., are laminated on a base material. CONSTITUTION:A pressure sensitive recording layer 2 containing a color coupler and a developer of which both or either are contained in a microcapsule, a polyolefin resin laminated layer 3, an electron beam setting resin layer 4 containing a radical polymerization inhibitor by a concentration of 1000-10000ppm per weight of the electron beam setting resin, and an opaque covering sheet 5 are successively laminated on a side surface of a base material to prepare a thermosensitive recording sheet. There are hydroquinone group, dichlorobenzoquinone group, etc., as concrete examples of the radical polymerization inhibitor, and there is a compound having ethylene unsaturated bond as a concrete example of the electron beam setting resin. Further, there are glassine paper, wood free paper, art paper, coated paper, etc., as the base material 1 and the opaque covering sheet 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to pressure-sensitive recording, and is a pressure-sensitive recording sheet in which a single-form self-coloring type pressure-sensitive recording layer provided on a support and an opaque coating sheet are integrated. , Non-exposed recording, copyability, water resistance, chemical resistance, oil resistance, scratch resistance, dust generation control type recording sheet for records, labels, slips, correspondence, entertainment, clean room A pressure-sensitive recording sheet that can be used as a recording sheet.

[0002]

2. Description of the Related Art The pressure-sensitive recording layer used in the present invention is a self-coloring pressure-sensitive recording type, which is developed from so-called carbonless copying paper. Also called paper. Its composition is a process of applying a coating of microcapsules containing a colorless dye (hereinafter referred to as a color former) on a support, and electron-accepting properties of acid clay, phenolic resin, organic acid substances, etc. on the coating. Conveniently the process of applying a substance (hereinafter referred to as a color developer) and a manufacturing method by two-layer coating consisting of two steps (including those in which the coating order is reversed), the above two components, or any one component Manufacturing method by microencapsulation, uniform mixing, and single layer coating (Japanese Patent Publication No.
No. 7-16096) is known. In such a self-coloring pressure-sensitive recording sheet, a color developing agent and a color developing agent are present in the vicinity, so a printed image with a high color density is easily obtained, but unintentional unintentional due to friction during manufacturing or handling. There is a problem that colored stains are likely to occur. As described above, the self-coloring pressure-sensitive recording sheet is destined to satisfy both the practically required coloring performance and the suppression of unnecessary coloring stains under the conditions under which it is used. Efforts are being made to satisfy both conflicting properties of dirt.

Further, in the self-coloring type pressure-sensitive recording sheet, the pressure-sensitive information is inevitably exposed to the public, and if it is desired to hide the information content, it should be put in a separate bag. I had to do it.

Up to now, for example, a method of providing a laminate layer by a vacuum adhesion method on a recording layer of a self-coloring pressure-sensitive recording sheet (Japanese Patent Publication No. Sho 49-10857) or a recording having a plastic layer by a melt lamination method. Known examples include a sheet (Japanese Utility Model Publication No. 52-149709) and a release layer provided on these protective layers. However, in reality, when a protective layer is provided by fusion lamination or lamination, unnecessary color stains can be prevented, but basically it is premised that the pressure-sensitive recording portion is exposed. The issue of record secrecy could not be resolved. In addition, a heat-sealing or thermoplastic resin coating layer is provided on the recording layer of a self-coloring type pressure-sensitive recording sheet, and the back surface is overlaid with an opaque coating sheet coated with a hot-melt type or thermoplastic type heat-sealing adhesive. , There is a method of integrating by hot pressing, but if it is hot pressed enough to be integrated, color fog in the pressure-sensitive recording layer will be caused and the commercial value will be lost, or resin with adhesive strength much weaker than adhesive strength will be used. There was no choice but to carry out integration with a light press by the adhesive force. Although this type of pressure-sensitive recording sheet has the concealment of recording,
Since it could be easily reattached, the confidentiality of the record was low.

In order to solve the above problems, the present applicants have proposed a pressure-sensitive recording layer, a polyolefin resin laminate layer, an electron beam as a pressure-sensitive recording sheet of a type that does not re-adhere once the opaque coating sheet is peeled off. An application was filed for a pressure-sensitive recording sheet in which a curable resin layer and an opaque coating sheet were sequentially provided. The pressure-sensitive recording sheet produced by this method not only has good color developability, water resistance, oil resistance, abrasion resistance, etc., but also has the complete nondisclosure of information, and the opaque coated sheet once peeled Since it was not glued, the confidentiality of information was high. In particular, in the step of integrating the sheet having the pressure-sensitive recording layer and the opaque coating sheet, since the integration can be performed with almost no pressing or heating, pressure fog does not occur in the pressure-sensitive recording layer, which is excellent. A pressure-sensitive recording sheet having a smooth background was obtained.

As a result of further studies on the pressure-sensitive recording sheet prepared by the above method, the present applicants have confirmed that the following problems may occur in actual use. That is, there is a problem that the adhesive strength between the opaque coating sheet and the polyolefin resin laminate layer becomes heavy and it is difficult to peel off when it is stored for a long time at a high temperature that imitates the inside of a post under the hot sun. This trouble not only hinders the reading of the pressure-sensitive copy recording contents,
The opaque coating sheet is torn, which is unfavorable in terms of appearance and significantly impairs the commercial value.

[0007]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a self-coloring type pressure-sensitive recording sheet in which an opaque coating sheet is integrated by using an electron beam curable resin, but sacrifice its original self-coloring property. Without changing the adhesive strength does not change even if stored at high temperature, and keeps information private if necessary,
An object of the present invention is to provide the pressure-sensitive recording sheet in which the peelability of the opaque coating sheet is good.

[0008]

Means for Solving the Problems As a result of intensive studies on the above problems, the present inventors have found the following solution. That is, a pressure-sensitive recording layer, a polyolefin resin laminate layer, and an electron beam, each of which is formed by laminating a color-forming agent or a color-developing agent, both or one of which is microencapsulated, individually on one surface of a support, or by mixing and coating them. Curable resin layer,
In a pressure-sensitive recording sheet in which an opaque coating sheet is sequentially provided, a radical polymerization inhibitor is contained in the electron beam curable resin layer in an amount of 1000 ppm to 10000 per weight of the electron beam curable resin.
It is an invention of a pressure-sensitive recording sheet characterized by containing at a concentration of ppm.

The present invention will be described in detail below. In the pressure-sensitive recording sheet of the present invention, the adhesive resin forming the electron beam curable resin layer provided on the recording surface by the action of the polyolefin resin laminate layer does not soak into the pressure-sensitive recording layer and is high during pressure-sensitive recording. Since the color density is obtained, the gloss, scratch resistance, and abrasion resistance of the printed surface are excellent, and because it is integrated with the opaque coating sheet, the pressure-sensitive recorded information should not be disclosed to the outside and handled without being exposed. The pressure-sensitive recorded information can be read inside by peeling off the opaque coating sheet as required. Once peeled off, the opaque coated sheet does not re-adhere, so the confidentiality is perfect. When a developer layer is provided on the surface of the opaque cover sheet, pressure-sensitive printing can be performed accurately on the surface of the opaque cover sheet if pressure-sensitive printing is performed by superimposing it on top paper coated with a color former or capsules. be able to. If you want to develop color only on the internal pressure-sensitive recording layer, you can do blank ejection with a printer without the ink ribbon, or use the upper paper to apply desensitizing ink on the color developer layer. By doing so, it is possible to suppress color development on the opaque coating sheet.

When an adhesive resin that does not dissolve in the polyolefin resin is applied on the polyolefin resin laminate layer and is sufficiently cured or crosslinked, the solidified electron beam curable resin layer has a cohesive force or a light anchor effect. Although it is adhered to the polyolefin resin laminate layer, it can be separated (peeled) from the polyolefin resin laminate layer with a light force. When separated once, the resin forming the electron beam curable resin layer is sufficiently solidified, so that it is not adhered to the polyolefin resin laminate layer again by pressurization or heating. The polyolefin resin laminate layer and the solidified electron beam curable resin layer transmit the writing pressure with almost no dispersion and absorption, so high color density can be obtained during pressure sensitive recording, and gloss and scratch resistance of the printed surface can be obtained. Since it has excellent abrasion resistance, and has an electron beam curable resin layer and an opaque coating sheet on the polyolefin resin laminate layer, it is possible to handle pressure-sensitive recorded information to the outside and handle it without exposing it. Further, by peeling off the opaque cover sheet as needed, the information pressure-sensitively recorded inside can be read. Furthermore, for the reasons stated above,
The information once disclosed has a characteristic that it cannot be hidden again (anti-redeposition property).

In the present invention, an epoch-making point is that the electron beam curable resin layer contains a radical polymerization inhibitor at a concentration of 1000 ppm to 10000 ppm based on the weight of the electron beam curable resin. By mixing the radical polymerization inhibitor in the electron beam curable resin layer at a constant weight mixing ratio, the adhesion between the opaque coating sheet and the polyolefin resin laminate layer is not affected by electron beam irradiation, and the mixture is stored under high temperature storage. The deterioration or overpolymerization of the electron beam cured resin in (3) is suppressed, and the pressure-sensitive recording sheet having good releasability for a long period of time can be produced.

Further, surprisingly, when the radical polymerization inhibitor is contained in the electron beam curable resin layer, the opaque coating sheet and the polyolefin resin laminate layer can be sufficiently adhered by electron beam irradiation, and the opaque coating sheet can be easily formed. It was confirmed that an additional desirable effect that the appropriate range of the electron beam irradiation amount capable of peeling can be set wide is set. This phenomenon is due to the fact that in the process of adhering the opaque cover sheet and the polyolefin resin laminate layer by electron beam irradiation, the opaque cover sheet becomes the polyolefin resin laminate layer even when more than necessary electron beam irradiation is performed due to the influence of voltage and speed. This is an important factor to avoid the trouble of excessive adhesion.

When the radical polymerization inhibitor mixed in the electron beam curable resin layer is less than the range shown in the present invention,
The opaque coating sheet and the polyolefin resin laminate layer are excessively adhered to each other due to overpolymerization of the electron beam-curable resin under storage at high temperature, which causes a fatal problem of deteriorating the releasability of the opaque coating sheet. When the radical polymerization inhibitor mixed in the electron beam curable resin layer is more than the range shown in the present invention, the curing of the electron beam curable resin layer due to electron beam irradiation is excessively suppressed, and the electron beam curable resin is sufficient. When the electron beam irradiation is performed to such a degree that it is hardened, the opaque coating sheet or the support may be deteriorated.

As the support and the opaque coating sheet used in the pressure-sensitive recording sheet of the present invention, general paper such as glassine paper, high-quality paper, art paper, coated paper, cast paper and the like can be used, wood pulp, Raw materials commonly used in papermaking, such as synthetic pulp, fillers, sizing agents, paper-strengthening agents, and dyes, can be used as necessary.
Further, plastic sheets such as polyethylene, polypropylene, polyethylene terephthalate, polyamide, polyvinyl chloride, polyvinylidene chloride, and polymethylpentene, and synthetic papers and nonwoven fabrics made of these synthetic fibers,
Or laminated paper with synthetic resin laminated on one side or both sides, metal foil, or laminated product of metal foil and paper, vapor-deposited paper, opaque sheet subjected to hologram treatment,
It is also possible to use a laminated product with a synthetic resin film, mica paper, glass paper and the like. These supports can be made opaque with inorganic or organic pigments, inks, toners and the like.

The pressure-sensitive recording layer that can be used in the present invention is not particularly limited, and any conventionally known one can be used. For example, a method of microencapsulation, a wall material of the microcapsule, a color former, an oil dissolving the color former, a color developer, an adhesive resin, a microcapsule protective agent, or the like. Examples of the microencapsulation method include a coacervation method (US Pat. No. 2,800,458), an interfacial polymerization method (Japanese Patent Publication No. 47-1763, etc.), an in situ polymerization method (Japanese Patent Publication No. 51-9079, etc.). Etc. can be used.

Polyurethane, polyurea, epoxy resin, urea / formalin resin, melamine / formalin resin and the like can be used as the wall material of the microcapsule.

As the color former, triallylmethane compounds, diarylmethane compounds, xanthene compounds,
A thiazine-based compound, a spiropyran-based compound, or the like can be used, and is not particularly limited as long as it is generally used for a pressure-sensitive recording material or a heat-sensitive recording material.

As oils for dissolving the color former, aromatic synthetic oils such as diarylalkane series, alkylnaphthalene series, alkylated biphenyls and hydrogenated terphenyls, and aliphatic synthetic oils such as kerosene, naphtha, paraffin oil and chlorinated paraffins. Oils, cottonseed oil, soybean oil, vegetable oils such as flaxseed oil and the like can be used.

As the protective agent for the microcapsules, cellulose powder, starch particles, talc, calcined kaolin, calcium carbonate and the like can be used.

Examples of developers include clays (eg, acid clay, attapulgite, etc.), organic acids (eg, aromatic carboxy compounds such as salicylic acid, or metal salts thereof), mixtures of organic acids and metal compounds, An acidic polymer (for example, phenol-formaldehyde resin, salicylic acid-based resin, or a metal salt thereof) or the like can be used.

In the present invention, as the binder used for forming the pressure-sensitive recording layer, starches, cellulose derivatives such as hydroxyethyl cellulose, methyl cellulose, ethyl cellulose and carboxymethyl cellulose, proteins such as casein and gelatin, oxidized starch and ester compounds. Aqueous natural polymer compounds such as saccharose such as starch, polyvinyl alcohol, modified polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, sodium polyacrylate, acrylic acid amide / acrylic acid ester copolymer, acrylic acid amide / acrylic acid ester / Methacrylic acid terpolymer, styrene /
Water-soluble synthetic polymer compounds such as alkali salts of maleic anhydride copolymers, latex, polyacrylamide, styrene / maleic anhydride copolymers, latexes, water-soluble alkali salts of ethylene / maleic anhydride copolymers, etc. Adhesive resin, polyvinyl acetate, polyurethane, polyacrylic acid ester, styrene / butadiene copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer, acrylonitrile / butadiene / acrylic acid copolymer, ethylene / Examples thereof include latex such as vinyl acetate copolymer.

Pigments used in the pressure-sensitive recording layer, the polyolefin resin laminate layer, or the electron beam curable resin layer include diatomaceous earth, talc, kaolin, calcined kaolin,
Examples thereof include calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide, silicon oxide, aluminum hydroxide and urea-formalin resin.

In addition, zinc stearate as an auxiliary agent,
Waxes such as higher fatty acid metal salts such as calcium stearate, paraffin, oxidized paraffin, polyethylene, oxidized polyethylene, stearamide, castor wax, etc., dispersant such as sodium dioctylsulfosuccinate, sulfonic acid modified polyvinyl alcohol, benzophenone type, An ultraviolet absorber such as a benzotriazole type, a surfactant, a fluorescent dye and the like are added as necessary.

In the pressure-sensitive recording sheet of the present invention, the method for forming the pressure-sensitive recording layer includes a blade coating method, an air knife coating method, a gravure coating method, a roll coating coating method,
Known coating methods such as a bar coating method and a drop curtain coating method can be used. The pressure-sensitive recording layer is preferably smoothed.

In addition, a back coat is applied to prevent curling, a conductive treatment is applied to prevent jamming, and an undercoat layer is provided between the support and the pressure sensitive recording layer. Various known techniques in 1) can be added as necessary.

Further, as the constitution of the present invention, calcium carbonate, talc, silica, clay, barium sulfate, magnesium carbonate, magnesium silicate, between the support and the pressure-sensitive recording layer are used to obtain a high color density. Inorganic pigments such as lead sulfate, lead white, zinc white, zinc sulfide, satin white, titanium oxide, antimony oxide, mica, bentonite, calcium silicate, gypsum, aluminum hydroxide, or polystyrene, polyvinyltoluene, styrene / divinylbenzene There is no problem in providing an undercoat layer containing fine organic pigments such as polymers, polymethylmethacrylate, urea / formaldehyde polymers, and polyethylene.

Examples of the polyolefin resin which constitutes the polyolefin resin laminate layer include the following substances. As polyethylene, high-density polyethylene,
Low density polyethylene, medium density polyethylene, linear low density polyethylene, ultra high molecular weight polyethylene, polypropylene as isotactic, atactic, a mixture thereof, a random copolymer or a block copolymer with ethylene, and other poly-3- Methyl pentene-1,
Polyethylene glycol terephthalate, polyvinyl chloride, polyvinylidene chloride, eval, ethylene vinyl acetate copolymer and the like can be used alone or in combination. However, considering the adhesiveness to the electron beam curable resin layer, the peeling property, and the anti-re-adhesion property, a polyolefin containing polyethylene, polypropylene, or polymethylpentene (poly-4-methylpentene-1, TPX) as a main component. It is preferably a resin. The polyolefin resin laminate can be provided on the pressure-sensitive recording layer by melt extrusion of the above substances. As a pretreatment for the melt extrusion, the pressure-sensitive recording layer may be subjected to a known treatment such as corona treatment for improving the adhesiveness.

If necessary, an aqueous intermediate layer for improving the adhesiveness can be provided between the pressure-sensitive recording layer and the polyolefin resin laminate layer in a coating amount range that does not lower the pressure-sensitive recording sensitivity.

For the polyolefin resin laminate layer, a laminator such as a general melt extrusion die, T die, and multi-layer simultaneous extrusion die can be used. Also, a polyolefin resin laminate layer can be obtained by adhering a polyolefin resin film to a pressure-sensitive recording layer or an aqueous intermediate layer via an electron beam curable resin layer. Further, the polyolefin resin laminate layer provided on the pressure-sensitive recording layer and the polyolefin resin laminate layer provided on the opaque coating layer may be superposed and bonded by heat fusion.
It is not so preferable due to the restriction of pressure fog on the pressure-sensitive recording layer.

In the present invention, examples of the resin that can be used as the non-silicone electron beam curable resin include compounds having an ethylenically unsaturated bond, and more specifically, the following resins are included.

(1) Poly (meth) acrylate of aliphatic, alicyclic, aromatic, araliphatic polyhydric alcohol and polyalkylene glycol (2) of aliphatic, alicyclic, aromatic, araliphatic Poly (meth) acrylate of polyhydric alcohol obtained by adding alkylene oxide to polyhydric alcohol (3) Polyester poly (meth) acrylate (4) Polyurethane poly (meth) acrylate (5) Epoxy poly (meth) acrylate (6) Polyamide Poly (meth) acrylate (7) Poly (meth) acryloyloxyalkyl phosphate ester (8) Vinyl- or diene-based compound having a (meth) acryloyloxy group at the side chain or terminal (9) Monofunctional (meth) acrylate , Vinylpyrrolidone, (meth) acryloyl compound (10) Ethylenic fatigue Cyano compound having a bond (11) Mono- or polycarboxylic acid having an ethylenically unsaturated bond, and their alkali metal salts, ammonium salts, amine salts, etc. (12) Ethylenically unsaturated (meth) acrylamide or alkyl-substituted (meth) ) Acrylamide and its multimers (13) Vinyllactam and polyvinyllactam compounds (14) Polyether having ethylenically unsaturated bond and its ester (15) Alcohol ester having ethylenically unsaturated bond (16) Ethylenically unsaturated Polyalcohol having bond and ester thereof (17) Aromatic compound having one or more ethylenically unsaturated bond such as styrene and divinylbenzene (18) Polyorganosiloxane having (meth) acryloyloxy group in side chain or terminal Service (19) Multimers or oligoester (meth) acrylate modified products of the compounds described in (1) to (18) above

These resins can be used alone or in combination with other resins. Also, it is possible to apply without a solvent or by dissolving in an organic solvent,
It can also be used by emulsifying it in water or an insoluble organic solvent, coating, drying and curing.

In the present invention, a radical polymerization inhibitor may be mixed and used in these electron beam curable resins. The action of the radical polymerization inhibitor when the radical polymerization inhibitor is mixed in the range shown in the present invention cannot be clearly explained, but it is presumed that unreacted radicals trapped in the electron beam curable resin cured by electron beam irradiation. It is considered that the species is inactivated by the radical polymerization inhibitor, suppresses overpolymerization even under high temperature storage, and maintains good peelability. Such radical polymerization inhibitors include hydroquinones, dichlorobenzoquinones, trinitrobenzenes, nitrosobenzenes, butylcatechols, picric acids, nitrobenzoic acids, oxygen and active oxygen,
A generally known radical polymerization inhibitor such as cupric chloride, ferric chloride, cobalt halide, diphenylpicrylhydrazyl, tetraethylphenylenediamine, chloranil and iodine can be used. These radical polymerization inhibitors can be used alone or as a solution in a mixture with the electron beam curable resin. It is also possible to use it by including it in the polyolefin laminate layer or in the opaque coating sheet.

Although a commercially available electron beam curable resin may contain a radical polymerization inhibitor, it is generally mixed only in an amount necessary to store the monomers and oligomers at room temperature. It is usually destroyed in the process of irradiation. The mixing amount of the radical polymerization inhibitor shown in the present invention is originally calculated in total with the amount of the radical polymerization inhibitor contained in the electron beam curable resin.

For the purpose of preventing blocking, thickening, and increasing the amount, it is possible to add organic or inorganic pigments to the resin forming these electron beam-curable resin layers. For example, kaolin, calcined kaolin, talc and wax. , Diatomaceous earth, calcium carbonate, aluminum hydroxide, magnesium hydroxide, magnesium carbonate, titanium oxide, barium carbonate, urea-formalin resin, and plastic beads such as styrene.

The coating amount of the electron beam curable resin layer is not limited, but it is desired that it is thinner for the purpose of avoiding a decrease in writing pressure as much as possible, preferably 0.5 to 30 g.
/ M ² or less, more preferably 1.0 to 20 g / m ² or less. Examples of the method for applying the resin for forming the electron beam curable resin layer of the present invention include a gravure roll and transfer roll coater, a bar coater, a roll coater, an air knife coater, a U comma coater, and AK.
KU coater, smoothing coater, micro gravure coater, air knife coater, reverse roll coater, 4 or 5 roll coater, blade coater, dip coater, bar coater, rod coater, kiss coater, gate roll coater, squeeze coater, falling curtain coater, Any coater such as a slide coater or a die coater may be used.

In the pressure-sensitive recording sheet according to the present invention,
The support, the pressure-sensitive recording layer, the polyolefin resin laminate layer, or the opaque coating sheet can be used by printing characters or a tint block. In the present invention,
In order to improve the adhesiveness and wettability, surface treatment such as corona treatment, ozone treatment, and flame treatment may be performed on the pressure-sensitive recording layer, the polyolefin resin laminate layer, and the opaque coating sheet.

The pressure-sensitive recording sheet of the present invention has a surface, a pressure-sensitive recording surface, a polyolefin resin laminate layer surface,
Alternatively, on the back surface, a color former layer or a developer layer, a protective coating layer, an electron beam curable resin layer, a release layer, a printing layer, a toner receiving layer, an ink receiving layer, a heat sensitive recording layer, a writing layer, a magnetic recording layer, etc. Can be provided alone or simultaneously. Further, the pressure-sensitive recording sheet of the present invention can be used as a series of copy sheets in combination with other pressure-sensitive recording sheet, back carbon copying sheet, adhesive sheet, printing sheet, transparent film and the like. Part or all of the recording sheet of the present invention, such as die cutting, separation of a part of the opaque coating sheet, perforations,
There is no problem in processing the feed holes for printers.

In the present invention, the electron beam penetrating power is used to cure the electron beam curable resin used by electron beam irradiation.
In terms of curing power, the acceleration voltage is 100 to 1000 KV,
It is more preferable to use an electron beam accelerator of 100 to 300 KV. The electron beam irradiation is preferably performed so that the absorbed dose in the opaque coating sheet is 0.5 to 5 Mrad. If the accelerating voltage or the electron beam irradiation amount is lower than this range, the electron beam penetrating power is too low to perform sufficient curing, which may cause color inhibition of the opaque coating sheet, and is also higher than this range. And not only the energy efficiency deteriorates, but also the decomposition of resin and additives,
Unfavorable effects on quality such as deterioration of strength of base paper appear,
In particular, the peelability of the opaque cover sheet is deteriorated.

The electron beam accelerator may be, for example, an electro curtain system, a scanning type, a double scanning type or the like. In the electron beam irradiation step, the overcoat layer can be cured while a synthetic resin film, a metal foil, a metal drum, or the like is brought into close contact with the overcoat layer and the surface shape thereof is transferred.

During electron beam irradiation, if the oxygen concentration is high, the curing of the electron beam curable resin is hindered, so nitrogen,
Oxygen concentration is less than 600ppm, preferably 400ppm by replacing with inert gas such as helium and carbon dioxide.
Irradiation is preferably performed in an atmosphere suppressed below.

[0042]

In the pressure-sensitive recording sheet of the present invention, since the polyolefin resin laminate layer on the pressure-sensitive recording layer is sufficiently cured or cross-linked with the adhesive resin which does not dissolve the polyolefin resin, the solidified electron beam curing is carried out. Although the functional resin layer adheres to the polyolefin resin laminate layer by cohesive force or a light anchor effect, it can be separated (peeled) from the polyolefin resin laminate layer by a light force. The opaque coating sheet and the adhesive resin are sufficiently adhered by a sufficient anchor effect, chemical bond and cohesive force. Once the adhesive resin is separated from the polyolefin resin laminate layer, the resin that constitutes the electron beam curable resin layer is sufficiently solidified, so adhere it to the polyolefin resin laminate layer again by applying pressure or heating. There is no. The polyolefin resin laminate layer and the solidified electron beam curable resin layer are
Since the pen pressure is transmitted with almost no dispersion or absorption,
Since high color density can be obtained at the time of pressure-sensitive recording, and the printed surface has excellent gloss, scratch resistance and abrasion resistance, and also has an electron beam curable resin layer and an opaque coating sheet on the polyolefin resin laminate layer. The pressure-sensitive recorded information can be handled without being exposed and exposed to the outside, and the opaque coated sheet can be peeled off as necessary to read the pressure-sensitive recorded information inside. Further, for the reasons described above, the information once disclosed has a characteristic that it cannot be hidden again (anti-re-adhesion property). Since the electron beam curable resin layer contains a certain amount of a radical polymerization inhibitor, the radical polymerization inhibitor suppresses overpolymerization even when the pressure-sensitive recording sheet is stored at a high temperature, and thus the peelability of the opaque coated sheet is improved. Can stay good. Also, the electron beam irradiation dose has a wide appropriate range in which the opaque coating sheet and the polyolefin resin laminate layer can be adhered to each other in a peelable manner.

[0043]

The present invention will be described in detail below with reference to examples, but the contents of the present invention are not limited to the examples.
All parts and% shown below are based on weight. In the following, Aronix is a trade name of an electron beam curable resin manufactured by Toagosei Chemical Industry Co., Ltd., and Kayarad is a trade name of an electron beam curable resin manufactured by Nippon Kayaku Co., Ltd.

Example 1 As a pressure-sensitive recording paper, a commercially available self-coloring type pressure-sensitive recording paper (manufactured by Mitsubishi Paper Mills, Diaself, Super N100, basis weight 100) was used.
g / m ² ) was used. Polypropylene (density: 0.908 g / cc, MI20) was laminated on the pressure-sensitive recording surface to a thickness of 14 μm by using a melt extrusion die as a polyolefin resin laminate layer. On the polyolefin resin laminate layer, a resin prepared by mixing Aronix M310 with a radical polymerization inhibitor (2,6-dichlorobenzoquinone) at a concentration of 1000 ppm as an electron beam curable resin was applied with an offset gravure coater to a concentration of 10 g / m ^2. , An opaque coating sheet having a developer layer thereon (Mitsubishi Paper Mills, under Mitsubishi NCR Super, N40, basis weight 40 g / m ² ) is overlapped with the non-coated surface, and an electron beam irradiation device (Energy Science Co., Electron curtain)
Introduced into the above and irradiated with an electron beam at an electron beam accelerating voltage of 200 kV to an absorbed dose of 1.5 Mrad to cure the electron beam curable resin mixture to obtain a target pressure sensitive recording sheet.

Example 2 The same procedure as in Example 1 was carried out except that the electron beam curable resin was changed as follows and the electron beam irradiation was adjusted to 2 Mrad.
A target pressure-sensitive recording sheet was obtained. Electron beam curable resin: Aronix M6400 Radical polymerization inhibitor: Hydroquinone monoethyl ether (5000 ppm)

Example 3 The same procedure as in Example 1 was carried out except that the electron beam curable resin was changed as follows and the electron beam irradiation was adjusted to 1 Mrad.
A target pressure-sensitive recording sheet was obtained. Electron beam curable resin: Aronix M8060 Radical polymerization inhibitor: Trinitrobenzene (10000
ppm)

Example 4 A target pressure-sensitive recording sheet was obtained in the same manner as in Example 3 except that the electron beam irradiation was adjusted to 2 Mrad.

Example 5 A target pressure-sensitive recording sheet was obtained in the same manner as in Example 3 except that the electron beam irradiation was changed to 4 Mrad.

Comparative Example 1 A target pressure-sensitive recording sheet was obtained in the same manner as in Example 1, except that the radical polymerization inhibitor was mixed with the electron beam curable resin at a concentration of 500 ppm.

Comparative Example 2 A target pressure-sensitive recording sheet was obtained in the same manner as in Example 2 except that the radical polymerization inhibitor was mixed with the electron beam curable resin at a concentration of 20000 ppm.

Comparative Example 3 A target pressure-sensitive recording sheet was obtained in the same manner as in Example 3 except that the radical polymerization inhibitor was not mixed with the electron beam curable resin.

Comparative Example 4 A target pressure-sensitive recording sheet was obtained in the same manner as in Example 4 except that the radical polymerization inhibitor was not mixed with the electron beam curable resin.

Comparative Example 5 A target pressure-sensitive recording sheet was obtained in the same manner as in Example 5, except that the radical polymerization inhibitor was not mixed with the electron beam curable resin.

Test: Examples 1 to 5 and Comparative Examples 1 to 5
The pressure-sensitive recording sheet obtained in 1. was evaluated as follows.

Peelability: Examples 1 to 5 and Comparative Examples 1 to 1
With respect to the pressure-sensitive recording sheet obtained in 5, the opaque coating sheet was peeled off and the peelability was evaluated. Good peelability when the opaque cover sheet can be easily peeled off and the electron beam curable resin layer is sufficiently cured. Is the opaque cover sheet adhered to the polyolefin resin laminate layer so that it cannot be peeled from the polyolefin resin laminate layer? The case where the electron beam curable resin layer was not sufficiently cured even though it could be peeled off was poorly peeled off, and the case where it was adhered to the extent that it was slightly hard to peel off was evaluated.

Adhesiveness: Examples 1 to 3 and Comparative Examples 1 to 1
In the pressure-sensitive recording sheet obtained in 3, the opaque coating sheet adheres to the polyolefin resin laminate layer,
An article having an adhesiveness sufficient to withstand the steps of mailing, cutting, and printing was judged to have excellent adhesiveness, and an article in which the opaque coating sheet was easily peeled off was judged to have poor adhesiveness.

Storage peelability: The pressure-sensitive recording sheets obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were stored for 3 days at 60 ° C. while the opaque coating sheet and the polyolefin resin laminate layer were integrated. After that, the opaque coated sheet was peeled off and a peelability test was conducted.
After storage at high temperature, the opaque coating sheet adheres to the polyolefin resin laminate layer, has sufficient adhesiveness to withstand the steps of mailing, cutting and printing, and can be easily peeled off. Those which were not adhered to the resin laminate layer or which were too strong to be easily peeled off were judged to have poor peelability. The respective results are shown in Table 1.

Color developability: Examples 1 to 3 and Comparative Examples 1 to
The pressure-sensitive recording sheet obtained in 3 was printed on the opaque coating sheet with an impact printer, and the opaque coating sheet was peeled off to confirm the color forming property under the polyolefin resin laminate layer. Color development was judged to be excellent in color development without any trouble in discrimination of recorded content, and poor color development was judged to be difficult to read recorded content.

[0059]

[Table 1]

Evaluation: Each of the pressure-sensitive recording sheets obtained in the examples had good internal recording when the opaque coating sheet was peeled off, and the peelability of the opaque coating sheet was a problem even during storage at high temperature. There wasn't. In the case of the pressure-sensitive recording sheet used in Comparative Examples, if the ratio of the radical polymerization inhibitor is too large or too small as compared with the range shown by the present invention,
There is a problem that the adhesiveness is lowered or the releasability under high temperature storage is not good. If the radical polymerization inhibitor is not contained, there is a problem in the releasability during storage at high temperature.

[0061]

In the pressure-sensitive recording sheet of the present invention, the adhesiveness and releasability of the opaque coating sheet can be maintained in a good condition even when stored at high temperature, and the pressure-sensitive recording can conceal the printed contents. This is effective for recording and communication when you want to hide the contents as a sheet.

[Brief description of drawings]

FIG. 1 is a sectional view of a pressure-sensitive recording sheet of the present invention.

[Explanation of symbols]

 1 Support 2 Self-coloring type pressure sensitive recording layer 3 Polyolefin resin laminate layer 4 Electron beam curable resin layer 5 Opaque coating sheet

Claims (1)

[Claims] 1. A pressure-sensitive recording layer or a polyolefin resin laminate layer, which is formed by laminating a color-forming agent or a color-developing agent, both or one of which is microencapsulated, individually on one surface of a support, or by mixing and coating them. In a pressure-sensitive recording sheet in which an electron beam curable resin layer and an opaque coating sheet are sequentially provided, a radical polymerization inhibitor is contained in the electron beam curable resin layer in an amount of 1000 ppm to 10000 ppm based on the weight of the electron beam curable resin.
A pressure-sensitive recording sheet, characterized in that it is contained at a concentration of.