JPH0770521A - Pressure-sensitive adhesive security sheet - Google Patents

Abstract

PURPOSE:To obtain a pressure-sensitive adhesive security sheet which has both of contradictory characteristics, i.e., necessary pressure bondability and resistance to unnecessary blocking, by providing a coating layer containing a non- self-adhering adhesive, a pigment and a tackifier on a support. CONSTITUTION:This sheet has a coating layer containing three basic constituents comprising an adhesive, a pigment and a tackifier formed on a support, and a non-self-adhering (non-tacky) adhesive is used as the adhesive. Once bonded by pressing, the sheet is not readily peeled by usual handling, while it can smoothly be peeled with good touch when intentionally peeled. It has both of contradictory characteristics, i.e., blocking resistance and necessary pressure bondability and is excellent in adhesion between the coating layer and the support.

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. When the sheet is a paper, the pressure-sensitive confidential sheet is apparently the same as ordinary paper, but the sheets and the sheet and other supports are Adhesion is completed instantly by applying an appropriate pressure when attempting to adhere to each other.The confidentiality of information can be protected by printing, copying, writing on the surface to be pressure bonded before pressure bonding. It is obtained by using.

[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, as a type in which a label is attached only to a portion where confidentiality is desired, there are Japanese Utility Model Publication No. 63-6870, Japanese Patent Application No. 1-270849, etc., and the amount of information that can be described is usual. The amount is just the same as that of a postcard, and when a large number of sheets are piled up and handled, there are disadvantages such as the collapse of the sheet bundle due to the difference in the paper thickness between the label-attached portion and other portions.

Further, a heat-sensitive adhesive sheet using a thermoplastic resin is described in JP-A-3-10895 and JP-A-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 Laid-Open No. 3-26697 discloses a sheet which can provide airtightness only by pressure and pressure bonding, but according to these methods, airtightness can be obtained by pressure and pressure bonding. However, a so-called blocking phenomenon occurs in which the coated surface and the uncoated surface are unnecessarily integrated with each other due to a weak pressing force in the manufacturing process, the printing process, or during the storage process, etc. until the final form of pressure bonding. 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.

[0006] Further, Japanese Patent Laid-Open Nos. 63-77984 and 63-186793 describe that self-adhesive pressure-sensitive adhesives are used. Since it is adherent and has adhesiveness to the adhesive itself, only one which is easy to block is obtained.

[0007]

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. This is a confidential sheet, and if it is used as a postcard, it can obtain twice as much information as a normal postcard and can keep the confidentiality of the information content. In this sheet, a coating layer for providing airtightness is provided on the entire surface of the support, the thickness of the entire surface of the sheet is constant, and even if a large amount is handled, the above-mentioned inconvenience does not occur. In addition, the object is to obtain a pressure-sensitive airtight sheet having excellent adhesiveness between the coating layer and the support by achieving both the required pressure-bonding performance when pressure-bonding and the contradictory characteristics of blocking. It is a thing.

[0008]

SUMMARY OF THE INVENTION The pressure sensitive confidential sheet of the present invention.
The main material contained in the coating layer is non-self-adhesive (non-adhesive)
Besides adhesives, they are pigments and tackifiers. The main purpose of using an adhesive is adhesion to the support, and the reason for using a pigment is to improve printability (ink absorption, ink receptivity, etc.) and prevent blocking, and the tackifier is a confidentiality. It is used to obtain pressure-bonding property for obtaining. These materials need to be used according to their purpose.

Although various kinds of adhesives can be used, in the present invention, any adhesive can be selected from a wide range as long as it has substantially no self-adhesiveness (adhesiveness). Self-adhesiveness (adhesiveness) is affected by temperature and humidity conditions,
In the present invention, the presence or absence of self-adhesiveness (adhesiveness) is determined by applying an adhesive to a high-quality paper of 150 g / m ^{2 in} a dry weight of 3 g / m ^{2 and} applying it in an atmosphere of a temperature of 20 ° C. and a humidity of 65%. A state in which layers are not adhered to each other when the layers are opposed to each other and a pressure of 300 Kg / cm ² is applied. The state of not being substantially adhered is specifically JIS-K-6833.
A T-type peeling force of 50 g / 25 mm or less based on the measurement method of -1980.

As the adhesive used in the present invention, any adhesive having non-self-adhesiveness (non-adhesiveness) satisfying the above conditions can be used, and examples thereof include polyurethane-based, synthetic rubber-based and natural rubber-based adhesives. , Vinyl chloride type, acrylic type, styrene-butadiene type, ethylene-vinyl acetate type, vinylidene chloride type, etc., as well as oxidized starch, etherified starch, esterified starch, casein, gum arabic,
Gelatin, sodium alginate, polyvinyl alcohol,
It is also possible to use water-soluble polymers such as carboxymethyl cellulose, polyethylene oxide, hydroxyethyl cellulose, polyacrylamide, polyvinylpyrrolidone, polyacrylic acid, and styrene-maleic anhydride copolymer. . Among them, polyethylene oxide having suitable softness and strong adhesion to the support and one having a glass transition temperature of −30 ° C. or higher are preferable. These adhesives can be used in combination of two or more kinds, but the target quality can be obtained by adjusting the kinds and amounts of the adhesive, pigment and tackifier used as the main components.

The adhesive has some degree of self-adhesiveness to some extent. However, even an adhesive having self-adhesiveness (adhesiveness) cannot be used together within a range that does not impair properties such as blocking. It is possible. The self-adhesiveness (adhesiveness) is closely related to the glass transition temperature of the adhesive, and the lower the glass transition temperature, the stronger the self-adhesiveness (adhesiveness). Specifically, -3
When the temperature is lower than 0 ° C., the self-adhesiveness (adhesiveness) becomes remarkable, but if it is used in a small amount, it can be used without impairing various properties. In that case, the higher the glass transition temperature of the other adhesive used together, the more the amount of the adhesive having self-adhesiveness (adhesiveness) used can be increased. However, it is desirable to avoid the use of an adhesive having self-adhesiveness (adhesiveness) even if it is used together with an adhesive having a high glass transition temperature.

The pigment used in the present invention is used for the purpose of improving the ink absorption and the ink inking property and preventing blocking in the printing process. You can For example, in addition to 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, a tackifier is used in addition to the adhesive and the pigment. The role of the tackifier is to give tackiness literally, but the tackifier itself does not have self-adhesiveness (tackiness) or adhesiveness to a support under normal conditions. But,
It is very useful that pressure-bonding performance for obtaining airtightness can be obtained only by applying an appropriate pressure.

Specifically, gum rosin, wood rosin,
In addition to rosins such as natural rosins such as tol oil rosin and disproportionated rosins, hydrogenated rosins, polymerized rosins, maleated rosins, fumarized rosins, formaldehyde modified rosins, modified rosins such as rosin phenolic resins, Terpene resin, C ₅ petroleum resin, C ₉ petroleum resin, styrene resin, alkylphenol resin, xylene resin, coumarone indene resin, carnauba wax, rice wax,
Beeswax, seraca wax, paraffin wax, polyethylene wax, higher fatty acids and their derivatives and metal salts,
Silicones and the like are used. Among them, the preferred one is
Powdered waxes (or dispersions), rosins and the like have appropriate softness.

The type and amount of tackifier can be freely adjusted and determined according to the type and amount of non-self-adhesive (non-adhesive) adhesive or pigment to be combined. When using an adhesive that has very little self-adhesiveness (tackiness), there is a tendency that a large amount of tackifier is required, and the characteristics of the three main components are grasped,
The target quality can be obtained by adjusting. 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 as required.

The support is not particularly limited, and may be, for example, a cellulosic material.
It is possible to use high-quality paper mainly composed of fibers, various synthetic papers, various coated papers, laminated papers, metal evaporated papers, and the like. The total amount of coating, which mainly consists of adhesives, pigments, and tackifiers, is 1-2.
0 g / m ² is suitable. 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 can be carried out by a conventionally known coating method such as an air knife coater, a blade coater, a bar coater, flexographic printing or screen printing.

[0017]

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 sodium polyacrylate aqueous solution having a concentration of 40% as a dispersant was added to 108 parts of water (Aron T-4 manufactured by Toagosei Kagaku Co., Ltd.).
0) After adding 5 parts, 200 parts of light calcium carbonate (manufactured by Shiraishi Industry Co., Ltd., Brilliant 15) was added and sufficiently dispersed using an Ace homogenizer manufactured by Nippon Seiki Co., Ltd.
There, 1000 parts of polyethylene oxide (PEO-1 manufactured by Dainichiseika Co., Ltd.) dissolved in 10% and 55% rosin-based tackifier (super ester E-7 manufactured by Arakawa Chemical Co., Ltd.) were added.
180 parts of 30-55) were added and mixed uniformly. The solution of 128 g / air as the coating amount to fine paper of m ² is 4g / m ² - Naifuko - data - to give the door - sensitive sensitive sheet was coated with.

Example 2 A pressure-sensitive airtight sheet was obtained in the same manner as in Example 1 except that the coating amount in Example 1 was 8 g / m ² with an air knife coater.

Example 3 A pressure sensitive sheet was obtained in the same manner as in Example 1 except that an acrylic adhesive (AE817-F manufactured by Nippon Synthetic Rubber Co., Ltd.) was used in place of the polyethylene oxide of Example 1. .

Example 4 Instead of the polyethylene oxide of Example 1, a styrene-butadiene adhesive (manufactured by Japan Synthetic Rubber Co., Ltd., JSR-0) was used.
A pressure-sensitive confidential sheet was obtained in the same manner as in Example 1 except that (635) was used.

Example 5 Polyethylene oxide of Example 1 and an acrylic adhesive having a glass transition temperature of -30 ° C. (AE, AE manufactured by Japan Synthetic Rubber Co., Ltd.)
A pressure-sensitive airtight sheet was obtained in the same manner as in Example 1 except that 816) was used in a solid content of 1: 1.

Comparative Example 1 A pressure-sensitive airtight seal was prepared in the same manner as in Example 1 except that an acrylic adhesive (AE923, manufactured by Japan Synthetic Rubber Co., Ltd., glass transition temperature -62 ° C.) was used in place of the polyethylene oxide of Example 1. -I got it.

Comparative Example 2 A pressure sensitive sheet was obtained in the same manner as in Comparative Example 1 except that the amount of the pigment of Comparative Example 1 was increased to 400 parts and no tackifier was used. The reason for this is to reduce the pressure-bonding property of the adhesive used.

Comparative Example 3 A natural rubber adhesive (Esdyne MS-32 manufactured by Sekisui Chemical Co., Ltd.) was used instead of the polyethylene oxide of Example 1.
A pressure-sensitive confidential sheet was obtained in the same manner as in Example 1 except that was used.

Comparative Example 4 Polyethylene oxide of Example 1 and an acrylic adhesive having a glass transition temperature of -47 ° C. (AE manufactured by Japan Synthetic Rubber Co., Ltd.)
A pressure-sensitive airtight sheet was obtained in the same manner as in Example 1 except that 942) was used in a solid content of 1: 1.

The pressure-sensitive confidential sheets obtained in the above Examples and Comparative Examples were evaluated for various characteristics according to the following test methods. (Self-adhesiveness) Only the adhesive used was evaluated, and the method is as described in the text. In addition, in Example 5 and Comparative Example 4, adhesives other than polyethylene oxide were evaluated. Judgment criteria ○ ---- There is no self-adhesion. Δ --- Almost no self-adhesion. × −−− There is self-adhesiveness.

(Adhesiveness to Support) Cerote was attached to the coated surface and peeled off when the coating layer was peeled off. Judgment criteria ○ ---- Almost no peeling of the coating layer. X --- Peeling of the coating layer is large.

(Pressurizing and pressure-bonding property) The coated surfaces were overlapped with each other facing each other, and a pressure-sensitive metal roll was used to bond them by applying a pressure of 300 kg / cm to prepare a confidential sheet, and the degree of peeling was evaluated. . In addition, only in Example 2, the coated surface and the uncoated surface were overlapped and pressure-bonded. Judgment Criteria O --- Adhesion is moderate and can be smoothly peeled off with a pleasant touch. Δ --- A little too heavy or too light. X --- It is too heavy and the support is damaged or hardly adhered.

(Blocking) Overlapping with the same combination of pressure and pressure bonding, temperature 40 ° C, humidity 90%, load 1K
The blocking state after standing for 1 week under the condition of g / cm ² was evaluated. 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.

Evaluation result

[Table 1]

[0032]

EFFECTS OF THE INVENTION The pressure-sensitive airtight sheet of the present invention uses an adhesive having no self-adhesiveness (adhesiveness) so that the necessary pressure-bonding property and unnecessary blocking property are contradictory. It was possible to achieve both at the same time, and the adhesion with the support was excellent.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location B42D 15/02 501 B

Claims (4)

[Claims] 1. A pressure-sensitive airtight sheet comprising a support and a coating layer containing three components of (A) adhesive (B) pigment (C) tackifier as a basic component, which is not used as an adhesive. A pressure-sensitive airtight sheet characterized by using a self-adhesive (non-adhesive) adhesive. 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 are opposed to each other and pressure-bonded. 4. The pressure-sensitive airtight sheet according to claim 1, wherein the non-self-adhesive (non-tacky) adhesive is polyethylene oxide.