JPH06313297A - Forgery-preventive paper - Google Patents

Abstract

PURPOSE:To obtain a forgery-preventive paper with increased discriminability without adverse effect on its paper layer strength. CONSTITUTION:This forgery-preventive paper contains small lumps of bacterial cellulose. Particularly, good quality paper is obtained in the case where small lumps of bacterial cellulose colored by dyes or pigments are employed. Depending on the culture conditions, various forms of bacterial celluloses are obtained. Since the chemical constitutions are the same as that of pulp fibers, the lumps can readily adhere to the fibers through hydrogen bonds, whereby the forgery-preventive paper of high paper layer strength and excellent discriminability is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-counterfeit paper which contains a small lump of bacterial cellulose to improve its distinguishability without deteriorating the strength of the paper layer.

[0002]

2. Description of the Related Art Various securities such as banknotes, checks, and stock certificates have various anti-counterfeit measures to prevent them from being tampered with or forged. Along with this, there is an increasing risk that they will be easily forged. Therefore, technology for preventing counterfeiting of paper used for securities has become important.

A technique for preventing forgery on paper is disclosed in Japanese Patent Publication No.
No. 0163328, Japanese Patent Application Laid-Open No. 61-019304, etc., a technique for producing paper by mixing a small amount of special fibers such as colored fibers and photochromic fibers into the paper stock, Japanese Patent Publication No. -47360, JP-A-6
As disclosed in, for example, JP-A-3-270897, a technique for drawing a colored or printed water-soluble polymer film or a paper fragment into paper, JP-A-63-182497, JP-A-63- There is a technique of inserting a safety thin wire into a paper layer as disclosed in Japanese Patent No. 216795.

[0004]

The method of mixing colored fibers is a classical method, but since the sheets are distinguished by the presence or absence of the fibers, the judgment is insufficient with the naked eye, and it is easy to be forged. There is. Further, in the method of drawing a water-soluble film or a piece of paper, the strength of the paper layer at that portion is weakened, which causes a problem of partial peeling of the paper during printing or subsequent processing. On the other hand, in the method of inserting the safety wire into the paper layer,
In addition to the local reduction in paper layer strength, there are problems such as the need for special equipment during papermaking.

The present invention relates to a technique for imparting distinguishability to an anti-counterfeit paper in which a paper layer contains some identifying substance without changing the paper layer strength. That is, an object of the present invention is to provide an anti-counterfeit paper with improved distinguishability without impairing the paper layer strength.

[0006]

[Means for Solving the Problems] In order to solve the above-mentioned problems, as a result of studying the kind of the identification substance to be contained in the paper layer, the intended forgery prevention paper can be obtained by containing a small lump of bacterial cellulose. It became clear. Bacterial cellulose can be obtained in various shapes such as granules, films, and blocks depending on the culture conditions, and because it has the same composition as pulp fibers, it can easily adhere to pulp fibers by hydrogen bonding. Are involved.

The bacterial cellulose of the present invention means any one of cellulose, a heteropolysaccharide having cellulose as a main chain, a glucan such as β-1,3, β-1,2, etc. produced by a microorganism, or a mixture thereof. It is a mixture. In the case of the heteropolysaccharide, the constituent components other than cellulose are hexose, pentose, mannose, fructose, galactose, xylose, arabinose, rhamnose, glucuronic acid and the like, and organic acids and the like.

Microorganisms that produce bacterial cellulose include, but are not limited to, Acetobacter aceti.
Acetobactor acetisubsp
xylinum) ATCC 10821 or the pasturean
(A.pasteurium), the same license (A.rancens), Sarcina ventriculi (Sarcina ventriculi), bacterium
Bacterium xyloides, bacteria of the genus Pseudomonas, bacteria of the genus Agrobacterium, etc. that produce bacterial cellulose can be used. In addition,
As a culture method, either static culture or aeration-agitation culture may be used.

Bacterial cellulose obtained by static culture is a gel-like film, and therefore, after being adjusted to a small lump of arbitrary shape,
Add to stock. Further, since the bacterial cellulose obtained by aeration and agitation culture is gel-like particles, it is possible to add a small lump of a predetermined size to the paper material by adjusting the culture conditions. There is no particular limitation on the size of the small lumps, but the average diameter is 0.5 mm considering the distinctiveness with the naked eye.
The above is preferable. If necessary, it is possible to add the gel after dehydrating it with a press or the like, and further to add the once-dried gel re-swelled.

When small pieces of bacterial cellulose are directly drawn into paper, a sheet having locally different light transmittance is obtained, and an anti-counterfeiting effect similar to a watermark can be expected. Further, by adding a small lump of bacterial cellulose which has been subjected to a coloring treatment in advance, a sheet having further excellent distinguishability can be obtained. In addition to the usual coloring dyes and pigments, special dyes and pigments such as fluorescent dyes, thermochromic pigments, photochromic pigments and magnetic pigments, and white pigments such as calcium carbonate and titanium dioxide can be used in the coloring treatment.

As the method of coloring, in addition to dyeing gel in water and fixing pigment, printing on dried film-shaped bacterial cellulose is also possible. However, it is necessary to add the dried bacterial cellulose to the stock after immersing it in water to swell it sufficiently.

The anti-counterfeit paper of the present invention contains, if necessary, dyes, fillers, sizing agents, fixing agents, dry paper strengthening agents and the like which are usually used in papermaking. further,
It is also possible to apply starch, polyvinyl alcohol, or the like on the paper surface by a size press or the like. For the production, a Fourdrinier paper machine, a cylinder paper machine, a twin wire paper machine, an on-top paper machine and the like are used, and a monolayer or a multilayer sheet is produced.

The anti-counterfeit paper of the present invention may be provided with various functional coating layers on the surface depending on the application. As a coating device at that time, an air knife coater, a gravure coater, a curtain coater, a die coater, a blade coater, or the like is used.

The anti-counterfeit paper of the present invention is a check, stock certificate,
It is used as a paper for gift certificates, or as a paper for cards, tickets, etc. on the surface of which a functional coating layer such as heat-sensitive and magnetic is provided.

[0015]

The anti-counterfeit paper containing a small lump of bacterial cellulose of the present invention has excellent paper layer strength and distinguishability.

[0016]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples. The present invention is not limited to the examples. All parts and% in the following are by weight. Further, the value indicating the coating amount is the weight after drying unless otherwise specified.

Example of preparation of bacterial cellulose Sucrose 5 g / dl, yeast extract 0.5 g / d
1, ammonium sulfate 0.5g / dl, potassium hydrogenphosphate 0.3g
/ Dl magnesium sulfate (MgSO ₄ 7H ₂ O) 0.0
50 ml of medium (pH 5.0) having a composition of 5 g / dl
Pour into a Erlenmeyer flask with a capacity of 200 ml, and
It was sterilized by steam for 20 minutes to prepare a culture solution. Next, yeast extract 0.5 g / dl and peptone 0.3 were added to this culture solution.
Acetobacter aceti subsp. xylinum (ATCC 10821) grown on a test tube slant agar (pH 6.0) having a composition of g / dl and mannitol 2.5 g / dl for 3 days at 30 ° C. Inoculated and cultured at 30 ° C.

After culturing for 15 days under the above-mentioned conditions, white bacterial cellulosic polysaccharide of 0.
A 5 mm thick gel-like film containing 5% was formed. After washing this gel film with water, it is dehydrated with a roll press to a thickness of 1 mm.
As a membrane of No. 2, a circular small piece of bacterial cellulose having a diameter of 2.5 mm was punched out.

Example 1 Hardwood kraft pulp and softwood kraft pulp 8: 2
The mixture of the above is refined (DDR) with a freeness of 35.
To 100 parts of pulp beaten to 0 ml, 5 parts of light calcium carbonate (TP121, manufactured by Okutama Kogyo Co., Ltd.), 0.07 part of alkyl ketene dimer size agent (SPK-903, manufactured by Arakawa Chemical Co., Ltd.), amphoteric starch (Kate). 321
0, made by Oji National Co., Ltd.) to 0.7 parts of paper stock,
The bacterial cellulose nodules in the preparation example were dried to 0.0
1 part was added. Using this raw material, paper having a basis weight of 84 g / m ² was produced by a Fourdrinier paper machine. The paper dried with a multi-cylinder dryer was size-pressed with a 3% aqueous solution of oxidized starch, dried, and then machine calendered. This paper is referred to as Sample 1.

Example 2 As a small lump of bacterial cellulose, the gel-like membrane after washing with water described in the Preparation Example was added to a 1% aqueous solution of Congo Red 24
Paper was obtained in the same manner as in Example 1 except that the product was immersed in the dye for a time, dyed, dehydrated by a press, and punched and used. This paper is referred to as Sample 2.

Example 3 The bacterial cellulose nodules of the preparation example were mixed with titanium dioxide (3).
Paper was obtained in the same manner as in Example 1 except that the material was stirred in a 0% aqueous solution for 24 hours, washed with water and dehydrated with a press and added to the stock. This paper is referred to as Sample 3.

Comparative Example 1 A paper was obtained in the same manner as in Example 1, except that 0.01 parts of congo red kraft pulp fibers dyed with Congo red were added instead of the small pieces of bacterial cellulose. This paper is referred to as Sample 4.

COMPARATIVE EXAMPLE 2 All procedures were the same as in Example 1 except that a 25 micron thick film-like PVA disk (diameter 2.5 mm) colored red was added in place of the bacterial cellulose nodules. Got the paper. This paper is referred to as Sample 5. Table 1 collectively shows the measurement results of the paper layer strength and the evaluation results of the distinguishability of the above samples.

The bond strengths in Table 1 are based on the TAPPI test method UM.
It is the value measured according to 403, and is 330 gcm / i.
If it is n ² or more, it can be judged that the paper layer has a strength enough to withstand a processing step such as printing. The distinguishability is the result of visual evaluation of the easiness of distinction from other papers, and indicates that A is the best and C is inferior. As the anti-counterfeit paper, B or more, preferably A is required.

[0025]

[Table 1]

From the comparison of Samples 1 to 3 and Samples 4 and 5 in Table 1, in the case of adding a small lump of bacterial cellulose, a counterfeit having good paper layer strength and differentiating property as compared with the case of producing by the conventional technique. It is clear that a protection sheet is obtained.
From the comparison between Sample 1 and Samples 2 and 3, it is also clear that the effects are particularly excellent when the colored bacterial cellulose nodules are added.

[0027]

The anti-counterfeit paper of the present invention, that is, the anti-counterfeit paper containing a small lump of bacterial cellulose has excellent paper layer strength and distinguishability. The effect is particularly remarkable when small bacterial cellulose particles colored with a dye, a pigment or the like are contained.

Claims (2)

[Claims] 1. An anti-counterfeit paper containing a small lump of bacterial cellulose. 2. The anti-counterfeit paper according to claim 1, wherein the small lumps of bacterial cellulose are colored with a dye, a pigment or the like.