JPH07195875A - Pressure-sensitive secret sheet - Google Patents

Abstract

PURPOSE:To provide a pressure-sensitive secret sheet constituted so that a pressure-sensitive coating layer is provided to the entire surface of a support and the surfaces of the coating layer formed by folding the support or the surface of the coating layer and the surface on the side opposite to the coating layer are superposed one upon another to be bonded under pressure and, later on, the pressure bonded surfaces are peeled to enable the transmission of data. CONSTITUTION:Among three kinds of main components of an adhesive, pigment and tackifier, the tackifier is encapsulated to be used. In a pressure-sensitive secret sheet, characteristics contrary to each other, that is, necessary pressure bonding properties and unnecessary blocking properties can be reconciled and the pressure-sensitive secret sheet improved in thermal discoloration or the sticking feeling of a coating surface can be obtained. Secret data is entered in a surface to be bonded under pressure before pressure bonding by printing, duplication or writing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive airtight sheet having a support provided with a coating layer for obtaining airtightness. A pressure-sensitive confidential sheet is, for example, when the sheet is paper, it looks like ordinary paper, but the sheets and this sheet and other supports are not. When trying to bond and, the bonding is instantly completed by applying an appropriate pressure, and the confidentiality of information is such as printing, copying, writing on the surface to be pressure bonded before pressure bonding. It is obtained by describing using the method.

[0002]

2. Description of the Related Art Conventionally, sealed letters have been frequently used to obtain confidentiality of information, but in recent years, various types of postcards have been devised which can provide confidentiality. For example,
No. 60-178125 and No. 2-217 of Japanese Utility Model Publication No. 60-178125 are used as the ones which use no-carbon copy paper or thermal recording paper.
No. 3 publication is available. These are very laborious because the manufacturing process and the processing process are complicated, and in terms of quality, there is a risk of loss of recorded information due to water wetting and plasticizers, etc., and they lack storability.

Further, a heat-sensitive adhesive sheet using a thermoplastic resin is described in JP-A-3-10895 and Japanese Utility Model Laid-Open No. 3-108595, but a heating device is required for adhesion by heat. , The base material may be deformed, distorted or damaged, and when printing (printing) with an electrophotographic printer, the heating element and the heat-sensitive adhesive layer do not need to be adhered when fixing the toner due to high heat. May cause machine damage.

Further, Japanese Patent Application Laid-Open No. 3-26697 discloses a sheet which can obtain airtightness only by pressure-bonding. According to these methods, pressure-tightness can provide airtightness. However, a so-called blocking phenomenon occurs in which the coated surface and the uncoated surface are unnecessarily integrated due to a weak pressing force in the manufacturing process, the printing process, or the process of reaching the final form of pressure bonding such as storage. easy. As an improvement, there is a description in JP-A-3-100087 in which an adhesion-suppressing substance layer is further provided on an adhesive layer. This method is effective for improving blocking, but is most necessary for a confidential sheet. It is difficult to obtain high pressure and pressure bonding performance.

Further, as an application of the encapsulation technique, Japanese Patent Laid-Open Nos. 1-25354 and 58-103 are known.
571, JP-A-58-136670, etc., but these are encapsulating a hydrophobic liquid, and since the core substance is a liquid, the sheet is cut or perforated. In that case, there is a drawback in that the core substance oozes out and stains the surroundings due to necessary damage during the coating layer processing.

[0006]

DISCLOSURE OF THE INVENTION According to the present invention, once pressure-bonded, it is not easily peeled off by ordinary handling, and when it is intentionally peeled, it can be peeled smoothly with a pleasant touch. It is a confidential sheet, and this sheet is provided with a coating layer for obtaining confidentiality on the entire surface of the support,
The purpose is to achieve both the required pressure-bonding performance when pressure-bonding and the contradictory properties of blocking. Adhesives, pigments, tackifiers, etc. are usually used for the coating layer, but the tackiness of the coating layer surface increases when a tackifier is used in combination. Especially when a low melting point tackifier is used, it appears remarkably. As an adverse effect of increasing the adhesiveness, blocking is likely to occur when the sheet is rolled up,
Sheet transport problems due to adhesiveness are also likely to occur.

[0007]

SUMMARY OF THE INVENTION The pressure sensitive confidential sheet of the present invention.
The main materials contained in the coating layer of the toner are a pigment and a tackifier in addition to the adhesive. The main purpose of using an adhesive is to obtain adhesiveness and adhesiveness with a support, and the reason for using a pigment is to improve printability (ink absorption, ink inking property, etc.) and prevent blocking, The tackifier is used for improving the pressure-bonding performance for obtaining airtightness.
These materials need to be used according to their purpose.

The adhesive used in the present invention can be selected from a wide range. For example, polyurethane-based, synthetic rubber-based, natural rubber-based, vinyl chloride-based, acrylic-based, styrene-butadiene-based, ethylene-vinyl acetate-based, vinylidene chloride-based, etc.
Tellurized starch, esterified starch, casein, gum arabic, gelatin, soda alginate, polyvinyl alcohol, carboxymethylcellulose, polyethylene oxide, hydroxyethylcellulose, polyacrylamide, polyvinylpyrrolidone, polyacrylic acid, Water-soluble polymers such as styrene-maleic anhydride copolymer can also be used. Among them, polyethylene oxide having a suitable softness and strong adhesion to a support and a glass transition temperature of -20 ° C are preferable.
Lower ones are preferred. These adhesives can be used in combination of two or more, and the target quality can be obtained by adjusting the types and amounts of the adhesive, pigment, and encapsulated tackifier used as the main components. it can.

The purpose of the pigment used in the present invention is to absorb ink in the printing process, to improve the ink inking property and to prevent blocking, and a wide range can be selected so long as this purpose is met. You can For example, metal oxides such as calcium, zinc, magnesium, aluminum, titanium, nickel, zirconium, manganese, tin, antimony, molybdenum, hydroxides, carbonates, silicates, kaolin, talc, active Inorganic pigments such as clay, urea formalin resin, melamine resin, styrene acrylic resin, benzoguanamine resin, starch particles and the like can also be used.

In the present invention, an encapsulated tackifier is used together with the adhesive and the pigment. The tackifier is generally referred to as a generic name for oligomers (medium molecular polymers having a dimer or more and a molecular weight of up to 10,000) having a molecular weight of several hundreds to several thousands, and is also called a tackifier. ing.

Specifically, gum rosin, wood rosin,
Natural rosins such as tol oil rosin, disproportionated rosin, hydrogenated rosin, polymerized rosin, maleated rosin, fumarized rosin, formaldehyde modified rosin, rosin phenol
Resin, modified rosin such as esterified rosin, terpene resin, aliphatic (C ₅ ) petroleum resin, aromatic (C ₉ ) petroleum resin, copolymerization (C ₅ / C ₉ ) Petroleum resin, alicyclic petroleum resin, styrene resin, alkylphenol resin, xylene resin, coumarone / indene resin, carnauba wax, rice wax, beeswax, seraca wax, paraffin wax, polyethylene wax, higher fatty acid and Examples thereof include derivatives, metal salts, silicones, and various solid plasticizers.

These tackifiers are used after being encapsulated. Of course, it is possible to use a part of the tackifier used without encapsulating it, as long as the required properties are not impaired. As the encapsulation method, a coacervation method, an in-situ method, an interfacial polymerization method and the like are known as main methods, and they are currently industrially applied. The encapsulation method used in the present invention is not particularly limited, and the above-mentioned encapsulation method or other encapsulation methods can sufficiently achieve the object of the present invention.

However, it will be more useful if the pressure required for bonding can be adjusted depending on the purpose of use of the pressure-sensitive airtight sheet and the method of pressing. That is, if you want to bond only with very strong pressure,
On the contrary, if it is desired to complete the adhesion with a weak pressure, it is considered to be more useful if the adhesive property can be provided flexibly according to the purpose.
This adjustment is possible by changing the thickness of the capsule coating and the particle size. In particular, by controlling the thickness of the film, the strength of the capsule film can be adjusted over a wide range. As for the encapsulation method in which the thickness and particle diameter of the film can be freely controlled, the encapsulation method having a synthetic resin film is more preferable than the coacervation method using gelatin because it is easier to control.

Although many capsules having a synthetic resin film are known, preferred examples in the present invention include urea-formalin resin capsules, melamine-formalin resin capsules, polyurethane resin capsules, polyurea resin capsules, and the like. . A particularly preferred membrane material is melamine-formalin resin. The average particle size of the capsule is adjusted depending on the purpose of use of the pressure-sensitive airtight sheet, the pressing method, the manufacturing process, the processing process, and the like.

Particularly useful in the present invention is that large capsules protruding from the surface of the coating layer can be obtained so that they are very difficult to block because they prevent the adherence between the laminated sheets and the sheets. At pressurization, confidentiality can be obtained without any problem. Also, the smaller capsules provide the original properties of the tackifier, similar to an ordinary non-encapsulated dispersion. The preferred particle size of the larger capsules is 10 to 100 microns, more preferably 2
0 to 60 microns. Those having a large particle size exceeding 100 microns are not preferable because the surface of the coating layer when applied is uncomfortable to the touch. The preferred particle size of the smaller capsules is 0.1 to 20 microns, more preferably 1 to 10 microns.

In the thus-encapsulated tackifier, the capsule film works effectively for blocking prevention, and it is desired to increase the effect by combining capsules of different sizes. In addition, a natural material such as a rosin-based or terpene-based material has a weak tackifying effect or is colored by heat or light, but these properties can be improved by encapsulation. . The type and amount of tackifier used for encapsulation can be freely controlled depending on the type and amount of adhesive or pigment to be combined. In addition, various auxiliary agents such as a defoaming agent, a preservative, a dispersant, a deterioration inhibitor, a thickener, and an antioxidant can be used in the coating layer.

The support used in the present invention is not particularly limited, and includes, for example, high-quality paper mainly composed of cellulose fibers, various synthetic papers, various coated papers, laminated papers, metallized papers, non-woven fabrics, Various plastic films can be used.

The total applied amount of the adhesive, pigment and tackifier is preferably 1 to 20 g / m ² . This application amount is about half of the application amount when the application surface and the application surface are pressure-bonded, and the application amount is about half that when the application surface and the opposite surface of the application surface are pressure-bonded. The coating method is air-knife coater,
The coating can be carried out by a conventionally known coating method such as a blade coater, a bar coater, flexographic printing or screen printing.

[0019]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.
In the examples and comparative examples, "parts" and "%" indicate parts by weight and% by weight unless otherwise specified.

Example 1 A tackifier (low molecular weight polyethylene, manufactured by Sanyo Kasei Co., Ltd., trade name Sun Wax 1) which was heated and melted in 200 parts of a 5% aqueous solution of a styrene-maleic anhydride copolymer having a pH of 5.8.
51) Add 180 parts and stir vigorously to give an average particle size of 5
Disperse emulsified to micron. Then melamine 20
Parts, 45 parts of 37% aqueous formaldehyde solution, and 3 parts of water
The pH was adjusted to pH 9.5 by adding 5 parts, and dissolved by heating to obtain a melamine-formaldehyde initial condensate. The mixture was added to the above emulsion and stirring was continued, and the mixture was reacted at 70 ° C. for 2 hours and then cooled to room temperature to obtain capsules having a tackifier as a core substance.

To 100 parts of this capsule dispersion liquid, 80 parts of an acrylic emulsion (manufactured by Nippon Synthetic Rubber Co., Ltd., trade name AE-944) as an adhesive in solid content was added. Synthetic silica (Mizukasil P-8, trade name, manufactured by Mizusawa Chemical Industry Co., Ltd.) dispersed with water so that the average particle diameter becomes 3 microns.
The solid content of 200 parts was added in an amount of 200 parts, and finally the liquid solid content was adjusted to 30% to obtain a pressure-sensitive airtight sheet coating liquid. This coating solution is 100 g / by air-knife coating.
pressure sensitive sensitive sheet was coated to a 6 g / m ² on a solids to fine paper of m ² - to give the door. After printing on the obtained pressure-sensitive confidential sheet, it is cut into a size twice as large as an official postcard, and folded over from the center so that the coated layer surfaces are in close contact with each other.
When pressure was applied at a pressure of 200 Kg / cm using a percalender, the bonding was completed instantly.

Example 2 A pressure-sensitive airtight sheet was obtained in the same manner as in Example 1 except that the capsule particles in Example 1 were dispersed and emulsified so that the average particle size was 40 microns.

Example 3 A terpene-based tackifier (manufactured by Yasuhara Chemical Co., Ltd.,
A pressure-sensitive confidential sheet was obtained in the same manner as in Example 1 except that the product name YS resin PX) was used.

Example 4 A pressure-sensitive confidential sheet was prepared in the same manner as in Example 1 except that a rosin type (manufactured by Arakawa Chemical Industry Co., Ltd., trade name: Superester A-750) was used as a tackifier. Obtained.

Example 5 A petroleum resin-based tackifier (Yasuhara Chemical Co., Ltd.,
A pressure-sensitive confidential sheet was obtained in the same manner as in Example 1 except that the product name YS resin 75) was used.

Example 6 A pressure-sensitive confidential sheet was obtained in the same manner as in Example 1 except that a solid plasticizer (trade name: DCHP, manufactured by Osaka Organic Chemical Industry Co., Ltd.) was used as a tackifier.

Comparative Example 1 The pressure-sensitive confidential sheet was prepared in the same manner as in Example 1 except that the low molecular weight polyethylene of Example 1 was not encapsulated but was dispersed to have the same particle size as the tackifier. -I got it.

Comparative Example 2 A pressure-sensitive confidential sheet was prepared in the same manner as in Example 1 except that the terpene-based tackifier of Example 3 was dispersed in the same particle size without being encapsulated. -I got it.

Comparative Example 3 The pressure-sensitive confidential sheet was prepared in the same manner as in Example 1 except that the rosin-based adhesive of Example 4 was dispersed in the same particle size without being encapsulated. -I got it.

COMPARATIVE EXAMPLE 4 The pressure-sensitive confidential material was prepared in the same manner as in Example 1 except that the petroleum resin system of Example 5 was dispersed in the same particle size without being encapsulated as the tackifier. I got a seat.

Comparative Example 5 The pressure-sensitive material was prepared in the same manner as in Example 1 except that the solid plasticizer of Example 6 was dispersed in the same particle size without being encapsulated as the tackifier. I got a confidential sheet.

The pressure-sensitive airtight sheets obtained in the above Examples and Comparative Examples were evaluated for various characteristics according to the following test methods. (Peeling Characteristics) All 11 kinds prepared in Examples and Comparative Examples were moderately adhered, and could be peeled smoothly with a pleasant touch.

(Blocking) The blocking state was evaluated after the coating layer surfaces were brought into close contact with each other and allowed to stand for 1 week under the conditions of a temperature of 40 ° C., a humidity of 90% and a load of 1 kg / cm ² . Judgment Criteria O --- Almost no blocking occurs. Δ --- It can be peeled off although it is slightly blocked. × −−− Strongly blocked and difficult to peel off.

(Coloring of coating surface) The coloring state after standing for 1 week in an atmosphere at a temperature of 60 ° C. was evaluated. Judgment Criteria O --- Almost no coloring is observed. Δ ---- Slightly colored. × −−− Severely colored.

(Adhesiveness of coated surface) Judgment criteria ○ ---- Almost same as ordinary high-quality paper. Δ --- A little sticky. × −−− The sticky feeling is large and it is sticky.

Evaluation result

[Table 1]

[0037]

In the pressure-sensitive airtight sheet of the present invention, by encapsulating the tackifier, it is possible to achieve both the necessary pressure-bonding property and the unnecessary blocking property, which are contradictory properties. there were. Further, by encapsulating, it was possible to improve discoloration due to heat and the like, and the tackiness of the coated surface.

Claims (4)

[Claims] 1. A pressure-sensitive airtight sheet comprising a support and a coating layer containing three components (A) adhesive (B) pigment (C) tackifier as a basic component, encapsulated in a pressure-sensitive confidential sheet. A pressure-sensitive confidential sheet characterized by using a tackifier. 2. Printing, copying, on the coating layer according to claim 1.
A pressure-sensitive confidential sheet, characterized in that after information is written by a method such as writing, the information writing surfaces are opposed to each other and pressure-bonded. 3. A pressure-sensitive confidential sheet, characterized in that the coated surface according to claim 1 and the surface opposite to the coated surface or the non-coated surface sheet are opposed to each other and pressure-bonded. 4. The pressure-sensitive airtight sheet according to claim 1, wherein the particle size of the encapsulated tackifier is 100 μm or less.