JPH11263086A - Confidential postcard paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To combine ink jet adaptability with water resistance by containing at least cation modified natural rubber and cationic resin in an adhesive layer in a confidential postcard provided with an adhesive layer containing an adhesive on at least one surface of a base material sheet. SOLUTION: A confidential postcard paper has an adhesive layer containing an adhesive and adhesive force control agent on one surface of a base material sheet, in which at least cation modified natural rubber and cationic resin are contained in the adhesive layer, thereby lessening blotting of ink and improving the adaptability of ink jet printer and water resistance. For such cation modified natural rubber, there is given matter cationizing an acrylic monomer being, e.g. natural rubber, methylmethacrylate, or the like during graft-polymerization. Also, for resin having a cationic property, there are given a cellulose derivative or the like such as polyvinyl alcohol, vinylacetate, and ethyl cellulose.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a confidential postcard used for various systems such as postcards and cards having confidentiality.

[0002]

2. Description of the Related Art In recent years, in accordance with the revision of the Postal Code, a sheet on which necessary information is recorded is folded in two or three.
Postcard systems with confidentiality have been commercialized and spread.
A postcard having such a confidential property usually has no adhesiveness on one side of the base sheet, and exhibits adhesiveness when pressed with the adhesive layers facing each other, and is peeled off after bonding. A confidential postcard having an adhesive layer capable of being used is used. Normally, confidential postcards are printed as fixed postcards, and then information such as personal information that is to be kept secret is printed on the adhesive layer surface, addresses and other information are printed on other parts using a printer, etc. A confidential postcard is formed by pressure lamination so that it cannot be seen from the outside. The confidential postcard is a postcard in which the recipient can obtain information by peeling off from the adhesive layer, and once peeled off, the adhesive surface does not have adhesiveness and thus does not become a state before peeling.

[0003] Initially, postcard systems that maintain confidentiality were printed on confidential postcard paper, printed with a high-speed laser printer, pressed with a dry sealer, and shipped by a relatively large-scale printing company. In recent years, the printing method has been changing from a high-speed laser printer method to a high-speed ink jet printer method provided with drying equipment capable of processing a large amount. In the ink jet system, ink droplets are made to fly by various recording systems and adhere to a recording sheet such as paper to record images, characters, and the like. Normally, the recording sheet has a high density of print dots, a bright and vivid color tone, no color sinking, and ink absorbs quickly, causing ink to flow or bleed even when print dots overlap. And there is a demand for less lateral diffusion. Since a high-speed inkjet printer uses an anionic dye ink, when printing on ordinary confidential postcard paper, the ink has no water resistance and runs off due to water. For this reason, studies were underway to use confidential postcard paper as inkjet-compatible paper.However, it was difficult to use confidential postcard paper as ink-jet-compatible paper. Was thought to have been resolved. However, pigment-based inks have poor fluidity when printed at high speed and are relatively easy to dry as compared with dye-based inks, and thus have problems such as frequent nozzle clogging. As a countermeasure, printing is performed at a line speed of about 1/3 to 1/4 compared with that of the dye system, and at present, the performance of the high-speed inkjet printer is not sufficiently exhibited.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the bleeding of the ink and to make it suitable for an ink jet printer.
An object of the present invention is to provide inexpensively confidential postcard paper that has excellent water resistance and satisfies adhesiveness and removability as confidential postcard paper.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, at least a cationically modified natural rubber and a cationically-modified natural rubber for improving water resistance and fixing property have been added to the adhesive layer. A confidential postcard having both ink jet aptitude and water resistance was obtained by incorporating a resin having the following characteristics.

The present invention relates to a confidential postcard paper having an adhesive layer containing an adhesive on at least one surface of a base sheet, wherein the adhesive layer contains at least a cation-modified natural rubber and a resin having a cationic property. It is a confidential postcard paper characterized by the following.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The confidential postcard paper of the present invention comprises an adhesive layer provided on one or both sides of a base sheet. Specifically, the adhesive layer has a re-peelable property (hereinafter, referred to as a re-peelable surface), and a form such as a two-fold postcard in which the adhesive layer is applied to only one surface, An adhesive layer provided on one side as a re-peelable side, and the other side as a non-removable side (hereinafter referred to as a permanent surface), for example, a form used as a tri-fold postcard formed by Z-folding or the like, or Examples of the base sheet having both sides having re-peelability and a six-face spread type confidential postcard are exemplified, but the processing form is not limited thereto. The adhesive layer is composed of an additive and other additives as necessary, including an adhesive and an adhesion control agent.

The present invention is characterized in that a cation-modified natural rubber is used as an adhesive. Examples of the cation-modified natural rubber include those obtained by cationizing an acrylic monomer such as methyl methacrylate to a natural rubber during graft polymerization. Examples of the cationic compound used for cationization include compounds having a quaternary ammonium group such as vinylbenzyltrimethylammonium chloride and lauryltrimethylammonium chloride; and secondary amino groups such as dimethylamine, diethylamine and methylethylamine. And the like. Among them, a compound having a quaternary ammonium group is preferably used from the viewpoint of the stability of the paint.

The present invention is characterized in that a cationic resin is added to the above-mentioned cation-modified natural rubber as an adhesive. Cation-modified natural rubber is a cation-modified natural rubber, which tends to increase hydrophilicity and reduce the water resistance of the coating film itself.If the natural rubber is strongly cationized, it extremely thickens or aggregates There is a tendency. Therefore, a cationic resin is added to the cation-modified natural rubber for the purpose of compensating the water resistance of the coating film and improving the fixability of the ink.

Examples of the cationic resin include cellulose derivatives such as polyvinyl alcohol, vinyl acetate, and ethyl cellulose; styrene butadiene copolymer; acrylate and methacrylate copolymers; and ethylene vinyl acetate copolymer. Adhesives such as vinyl-based polymers, urethane resins, polyester resins, and polyamide resins are cation-modified with secondary, tertiary amino groups or quaternary ammonium bases, and one or more types are used.

The amount of the cation-modified natural rubber in the adhesive layer is preferably 20 to 60% by weight based on the solid content. When the amount is less than 20% by weight, the strength of the adhesive layer becomes weak, and when the amount exceeds 60% by weight, the pigment on the surface of the adhesive layer is covered, whereby the ink absorbability is reduced and the suitability for ink jet is reduced. The amount of the cationic resin is preferably about 5 to 50% by weight based on the weight of the cation-modified natural rubber. Further, if the amount is too large, the performance is not improved and only the cost is increased. If the amount is less than 5% by weight, the fixing property and the water resistance of the ink are not exhibited.

As the adhesive force control agent, known inorganic and organic pigments for postcard paper can be used. For example, zinc oxide, titanium oxide, zeolite, calcium carbonate, clay, aluminum oxide, wheat starch, silica, alumina, colloidal silica, plastic pigment, polyethylene resin, polypropylene resin, fluororesin, etc. are used, but wheat starch, silica Are suitable for controlling the adhesive and are preferably used. Also, wheat starch is used as a spacer to prevent blocking. Those having a particle diameter of about 10 to 50 μm are used. Silica is preferable because it has excellent ink receptivity and improves printability and inkjet recording suitability. Fluorine-based resins are highly effective in preventing ink bleeding. Further, titanium oxide has a high hiding effect, and the hiding effect is further enhanced by mixing with silica.

In the adhesive layer, a pigment dispersant as an additive,
Thickeners, flow improvers, defoamers, defoamers, release agents, foaming agents, penetrants, coloring dyes, ultraviolet absorbers, antistatic agents, cationic, nonionic or amphoteric surfactants, An appropriate amount of an antioxidant, a preservative, a water-proofing agent and the like are blended.

Although there is no particular limitation on the base sheet, paper such as high quality paper, medium quality paper, art paper, coated paper, synthetic paper, synthetic resin film, metal foil, non-woven fabric, etc. may be used. Yes, these may be laminated or surface-treated. Among them, the use of inexpensive paper is preferable.

When the surface is coated, various coating methods such as a blade coater, a roll coater, an air knife coater, a bar coater, a gravure coater, and a curtain coater are used. Coaters, bar coaters, gravure coaters and the like are preferred. 2-30 as coating amount
It is in the range of g / m ^2, preferably in the range of 3 to 15 g / m ^2.

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

Example 1 Fine paper 81.3 g / m ² (O
KH70 Oji Paper Co., Ltd.) was coated with a coating for re-peeling surface having the following composition on a single side using a Meyer bar at a rate of 10 g / m2 per solid.
^Two coatings were performed and dried at a temperature of 100 ° C. for 1 minute using a hot air dryer.

-Paint composition for removable surface Titanium oxide (Taipek W-10, manufactured by Ishihara Sangyo Co., Ltd.) 20 parts Wheat starch (AS-225, manufactured by Chiba Starch Co., Ltd.) 30 parts Precipitated synthetic silica (Mizukasil P) -527, manufactured by Mizusawa Chemical Industry Co., Ltd.) 40 parts Fluorine-based fine particles (Hydrosser SST3, manufactured by Shamrock Co., Ltd.) 10 parts Cation-modified natural rubber-based latex (Furutite FB-3001, manufactured by Mitsui Fuller Co., Ltd.) 80 Part Cation-modified acrylic resin (T-900CX, manufactured by Mitsui Chemicals, Inc.) 20 parts

On the opposite side of the high-quality paper coated with the above-mentioned re-peelable surface paint, a permanent-surface paint having the following composition is applied by a Meyer bar at a rate of 10 g / m ² per solid, and then heated to 100 ° C. with a hot air drier. And dried for 1 minute to prepare confidential postcard paper (for tri-fold postcards).

-Paint formulation for permanent surface Titanium oxide (Taipek W-10, manufactured by Ishihara Sangyo Co., Ltd.) 10 parts Wheat starch (AS-225, manufactured by Chiba Starch Co., Ltd.) 20 parts Precipitated synthetic silica (Mizukasil P-) 527, manufactured by Mizusawa Chemical Industry Co., Ltd.) 30 parts Fluorine-based fine particles (Hydrosser SST3, manufactured by Shamrock Co., Ltd.) 10 parts Cation-modified natural rubber-based latex (Furutite FB-3001, manufactured by Mitsui Fuller Co., Ltd.) 150 parts Cation-modified acrylic resin (T-900CX, manufactured by Mitsui Chemicals, Inc.) 30 parts

Example 2 A confidential postcard (for three-fold postcards) was prepared in the same manner as in Example 1, except that 80 parts of the cation-modified natural rubber-based latex on the removable surface was changed to 40 parts.

Example 3 A confidential postcard (for three-fold postcards) was prepared in the same manner as in Example 1, except that 80 parts of the cation-modified natural rubber-based latex on the removable surface was changed to 130 parts.

Comparative Example 1 A confidential postcard (for three-fold postcards) was prepared in the same manner as in Example 1 except that the cation-modified natural rubber-based latex on the removable surface was changed to a natural rubber-based latex (Furtite FB-01-OK). ) Was prepared.

Comparative Example 2 A confidential postcard paper (for three-fold postcards) was prepared in the same manner as in Example 1 except that the cation-modified acrylic resin (T-900CX, manufactured by Mitsui Chemicals, Inc.) on the removable surface was omitted. did.

"Evaluation Method" (1) Ink Absorption Yellow, magenta, cyan, and black were printed using an ink jet printer MC-830 (manufactured by Epson Corporation), and the ink drying time was measured. ：: less than 10 seconds △: 10 seconds or more and less than 60 seconds ×: 60 seconds or more

(2) Ink bleeding and density Using an ink jet printer MC-830 (manufactured by Epson Corp.), yellow, magenta, cyan, and black were printed, and the dot shape was observed with a stereoscopic microscope to evaluate ink bleeding. . The concentration was visually evaluated. ：: no problem △: slight, but no practical problem ×: defective

(3) Water resistance of ink and coating layer Using an ink jet printer MC-830 (manufactured by Epson Corporation), yellow, magenta, cyan, and black are printed, and the printed paper is immersed in water for 1 minute. In the wet state, dropout of the ink on the printing surface was visually confirmed. Further, the water resistance of the coating layer was determined by rubbing the coating layer in a wet state, and visually checking the falling off. ：: No ink bleeding, no loss of coating layer △: Slight, but no practical problem ×: Poor

(4) Adhesion of Removable Surface Using a dry sealer (manufactured by Toppan Forms Co., Ltd.), the obtained confidential postcard paper (for tri-fold postcards) is cut into an appropriate size, and the removable surfaces are separated from each other. Was Z-folded so as to face each other, conditioned at 23 ° C. and a temperature and humidity condition of 65% for 24 hours, and passed through a press roll having a roll gap set to 150 μm and pressure-bonded to produce a confidential postcard. The obtained confidential postcard was peeled again by T-type peeling, and the peeled state and the state of the peeled surface were evaluated. ○: Re-peeled cleanly △: Re-peeled, but weak adhesion or partial substrate destruction occurred, but no problem in practical use ×: Substrate destruction occurred or peeled with low adhesive strength, practical problem Level

(5) Comprehensive Evaluation Comprehensive evaluation as confidential postcard paper was performed. ：: Very good as confidential postcard paper. ：: There is some problem as confidential postcard paper, but there is no practical problem. Δ: Applicable as confidential postcard paper, but care must be taken in handling such as preventing water from adhering because of poor water resistance. ×: There is a problem as confidential postcard paper, and it is at a level that cannot be used practically.

[0030]

[Table 1]

[0031]

According to the present invention, in a confidential postcard paper provided with an adhesive layer containing an adhesive on at least one or both sides of the base sheet according to the present invention, the adhesive layer comprises a cation-modified natural rubber and a resin having a cationic property. By containing the confidential ink, confidential postcard paper which has less ink bleeding, is suitable for an ink jet printer, has excellent water resistance, and satisfies adhesion and removability of confidential postcard paper can be obtained.

Claims (2)

[Claims] 1. A confidential postcard having an adhesive layer containing an adhesive and an adhesion control agent on at least one surface of a base sheet, wherein the adhesive layer contains at least a cation-modified natural rubber and a resin having a cationic property. Confidential postcard paper characterized by containing. 2. The confidential postcard paper according to claim 1, wherein the cation-modified natural rubber accounts for 20 to 60% by weight of the solid content of the adhesive layer.