JPS6319164Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a pressure-sensitive copying recording sheet having a tampering prevention mechanism. More specifically, the present invention relates to a pressure-sensitive copying recording sheet having a tampering prevention mechanism and capable of making a large number of copies.

Ordinary pressure-sensitive copying paper consists of a substantially colorless electron-donating compound (hereinafter referred to as a color former) and an electron-accepting compound (hereinafter referred to as a color developer) that reacts with the color former to produce a colored compound. ).For example, the most common pressure-sensitive copying paper is made of a sheet in which microcapsules containing a color former are coated on a support, and a sheet in which a color developer is coated on a support. The microcapsules are destroyed by pressure, etc.
A color forming agent and a color developer are brought into contact and reacted.

However, since the color forming agent and the color developer are substantially colorless compounds, this may be rather inconvenient depending on the application. For example, when the above-mentioned pressure-sensitive copy paper is used for receipts, etc., the sheet to which pressure is applied directly, that is, the surface coated with microcapsules, does not develop color because the two reactants are not involved, and therefore no color develops due to the pressure method. In fact, no traces remain on the front or back surfaces of the sheet coated with microcapsules.
Therefore, it can be easily tampered with and cannot function as a receipt.

A pressure-sensitive copying paper with a tamper-proofing mechanism that improves these drawbacks is disclosed in Utility Model Publication No. 35361/1971, but pressure-sensitive copying paper with a tampering-proofing mechanism and the ability to make multiple copies at once is Copy sheets were not known and it was difficult to obtain multiple tamper-proof copies of, for example, receipts.

Therefore, an object of the present invention is to obtain a pressure-sensitive recording sheet that has a tamper-proof mechanism and that can make a large number of copies at once.

The above purpose is to provide a recording sheet A having a self-coloring layer coated with microcapsules containing a color former and a color developer on at least one side of a support, and a recording sheet A containing a color former on one side of the support. A combination of one or more recording sheets B having a layer coated with microcapsules containing a color former and a color developer on the other surface of the support. This was achieved with a tamper-proof pressure-sensitive recording sheet featuring the following characteristics.

The present invention will be explained below with reference to the drawings. 1 and 2 show cross-sectional views of the pressure-sensitive copying recording sheet of the present invention, in which 1 is a support, 2 is a self-coloring layer coated with microcapsules containing a color former and a color developer. 3 indicates a layer coated with microcapsules containing a color former and/or a color developer. The recording sheet of this invention is made by overlapping sheets A and B and applying pressure from the top surface of sheet A with a ballpoint pen, iron pen, typewriter, etc., so that the top surface of each sheet develops color and at the same time the bottom surface of each sheet develops color. A large number of copies can be obtained and at the same time tampering is prevented. Note that although Figures 1 and 2 show the case where two B sheets are used,
One or more B sheets may be used, and the present invention is not limited to the combinations shown in FIGS. 1 and 2. The above microcapsules, color former, and color developer are coated on the support together with a binder, but when the microcapsules and the color former, or the microcapsules and the color developer are coated on the same surface of the support may be coated as a layer containing both microcapsules and color developer, or microcapsules and color developer, or may be applied as a layer containing both microcapsules and color developer separately.
It may be applied as more than one layer.

The microcapsules used in this invention contain an oily liquid in which a basic colorless coloring agent is dissolved.
These are microcapsules coated with a wall material made of a polymeric substance that is insoluble in both water and oil-based liquids.
It has an average particle size of ~100μ. As the wall material, those made of a combination of polycation and polyanion such as gelatin-gum arabic, or those made of a combination of condensed compositions such as polyisocyanate-polyamine, etc. are used.

A method for producing such microcapsules is a phase separation method from an aqueous solution (US Patent No. 2800457).
Interfacial polymerization method (Japanese Patent Publication No. 38-19574, Japanese Patent Publication No. 42-446, Japanese Patent Publication No. 42-771, etc.)
No. 42-2882, No. 42-2883, No. 42-8693, No. 42
-9654, Publication No. 42-11344, British Patent No.
950443, Specification No. 1046409, etc.), method by polymerization of wall material in oil droplets (Japanese Patent Publication No. 36-9168, No. 49)
-45133, etc.), or the melting and dispersion cooling method (British Patent No. 952807, British Patent No. 965074, etc.).

The color forming agent used in the present invention has the property of forming color by donating electrons or accepting protons such as acids, and is usually almost colorless, including lactones, lactams, sultones, and spiropyrans, but is not particularly limited. A compound having a partial skeleton such as , ester, or amide, and whose partial skeleton opens or cleaves upon contact with a color developer is used. Specifically, crystal violet lactone, benzoyl leucomethylene blue, malachite green lactone, rhodamine B lactam,
Examples include 1,3,3-trimethyl-6'-ethyl-8'-butoxyindolinobenzospiropyran.

These color formers are dissolved in a solvent and encapsulated. As the solvent used here, natural or synthetic oils can be used alone or in combination. Examples of solvents include cottonseed oil, kerosene, paraffin, naphthenic oil, alkylated biphenyl, alkylated terphenyl, alkylated naphthalene, diarylethane, triarylmethane, chlorinated paraffin, and the like.

Examples of the binder used in the present invention include styrene-butadiene rubber latex, styrene-butadiene, acrylonitrile latex,
latex such as styrene-maleic anhydride copolymer latex; protein (e.g. gelatin,
Water-soluble natural polymer compounds such as gum arabic, albumin, casein, etc.), cellulose (e.g., carboxymethyl cellulose, hydroxyethyl cellulose, etc.), sutucarose (e.g., agar, sodium alginate, starch, carboxymethyl starch, etc.); polyvinyl alcohol,
Water-soluble synthetic polymers such as polyvinylpyrrolidone, polyacrylic acid, and polyacrylamide; organic solvent-soluble polymers such as nitrocellulose, ethylcellulose, polyester, polyvinyl acetate, polyvinylidene chloride, and vinyl chloride-vinylidene chloride copolymers Examples include compounds.
These polymeric substances used as binders usually have a molecular weight of about 1000-10000000, especially 10000-
5,000,000.

In the present invention, it is preferable to use particles or fibrous substances that are solid at room temperature as the protective agent for the microcapsules. Specific examples include starch particles (such as British Patent No. 1232347), fine polymer powders (such as U.S. Patent No. 3625736), and microcapsule particles containing no coloring agent (such as British Patent No. 1235991).
Examples include inorganic particles such as talc, kaolin, bentonite, waxite, zinc oxide, titanium oxide, and alumina, and fine cellulose powder (US Pat. No. 3,625,736, etc.). When in particulate form, the average particle size is suitably from 3 to 50 microns, preferably from 5 to 40 microns, in volume average diameter. Furthermore, it is more effective if these particles are larger than the microcapsules containing the color former. On the other hand, in the case of a fibrous material, its length is suitably between 30 and 600 microns, preferably between 100 and 400 microns.

The color developer used in the present invention has the property of accepting electrons or donating protons, and is an adsorbed or reactive compound that develops color when it comes into contact with the above-mentioned color former, such as acid clay, bentonite, Clay minerals such as kaolin, phenols
Examples include formalin novolac, metal-treated novolac, and zinc salts of aromatic carboxylic acids.

Moreover, two or more types of the above color developers can also be used in combination.

The coating liquid containing a color developer as a main component used in this invention is a liquid in which the color developer is dissolved or dispersed together with a color developer binder in water or other solvent, and usually about 10 to
It was prepared to have a solid content concentration of about 60wt%.

As the color developer binder, latex binders such as acrylic ester latex, vinyl acetate latex, and styrene-butadiene latex are generally used. In particular, styrene-butadiene latex with an average degree of polymerization of 500 to 100,000 is used. Preferably, the amount used is 2 parts by weight or more, preferably 50 to 30 parts by weight, per 100 parts by weight of the color developer. Further, when a latex binder is used, other water-soluble binders can be used in combination, and the film surface strength, the dispersibility of the color developer, etc. can be adjusted by using the combination.

Water-soluble binders used in combination include proteins (e.g., gelatin, albumin, casein, etc.), cellulose (e.g., carboxymethyl cellulose, hydroxyethyl cellulose, etc.),
Water-soluble natural polymer compounds such as sutucarose (e.g. agar, sodium alginate, carboxymethyl starch, gum arabic, etc.); water-soluble synthetic polymer compounds such as polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polyacrylamide, and other latexes. is used.

In this case, the amount used is based on 100 parts by weight of the color developer.
It is preferable to use 20 parts by weight or less, and the total amount of the binder is preferably 40 parts by weight or less. If it is more than 40 parts by weight, the color developing ability decreases and it is also undesirable in terms of cost.

Water is most commonly used as a solvent for dissolving or dispersing the color developer and the color developer binder, but organic solvents such as methyl ethyl ketone, ethyl acetate, benzene, and toluene are also used.

Supports used in this invention include commonly used wood-free paper, medium-quality paper, recycled paper, machine-coated paper, art paper, cast-coated paper, synthetic paper, resin-coated paper, plastic film, etc. .

In the present invention, the amount of coating of the coating liquid mainly composed of microcapsules and color developer varies depending on the type of color developer used. For clays, the amount is 2 g/m2 or ^more , preferably 5 to 8 g/ ^m2 on a dry basis. For coating liquids mainly composed of microcapsules,
The appropriate concentration is at least 0.3 times, preferably 0.5 to 1.5 times the above amount.

On the other hand, when a phenolic resin or a metal salt of an aromatic carboxylic acid is used, the appropriate amount is 0.1 g/m ² or more, preferably 0.5 to 7 g/m ² , and the coating amount of the coating liquid containing microcapsules as the main component is appropriate. is suitably 0.5 times or more, preferably 0.5 to 1.5 times.

Embodiments of the present invention will be described below with reference to the drawings.

In Figures 3 to 8, 1 is a support, 4 is a microcapsule containing a coloring agent, 5 is an adsorbent solid acid such as clay, and 6 is a coloring agent such as a phenol or a metal salt of an aromatic carboxylic acid. 7 is an office tool that pressurizes, such as a ballpoint pen, iron pen, typewriter, etc., and 8 is the colored part where the microcapsules are destroyed by pressurization. show.

FIGS. 3 and 4 show the case where an adsorbent solid acid such as clay is used as a color developer for the self-coloring layer. In this case, it is desirable to have a color developer layer on another support that is in face-to-face contact with the self-coloring layer. The structure of the self-coloring layer may be either a single-layer structure in which microcapsules and a color developer are mixed, or a two-layer structure consisting of a layer containing microcapsules and a layer containing a color developer, and among these, a two-layer structure may be used. is not limited to this diagram.

Further, the color developing layer of the other adjoining support is not limited to this figure as long as it is a coating layer containing a color developer such as clay, phenol resin, aromatic carboxylic acid metal salt, etc. as a main component.

Figures 5 and 6 show color developers that are compatible with the oil in which the color former in the microcapsules is dissolved, such as phenolic resin, aromatic carboxylic acid metal salt, etc., as the color developer in the self-coloring layer. This shows the case where is used as the main component.

In FIG. 5 and FIG. 6, the layer structure of the self-coloring layer shows only an example of a two-layer structure, but it may also have a single-layer structure in which a color forming agent and a color developer are mixed in the same layer, or a capsule and color developing layer may be used. The location of the agent is not limited to this diagram.

On the other hand, unlike FIG. 3 or 4, the surface facing the self-coloring layer may be either the color developer layer or the capsule layer, and the oil in the destroyed capsule dissolves the color developer. , indicating that both sides are colored.

Figures 7 and 8 show that the writing utensil in step 5 is used when a recording utensil that does not contain coloring components such as ink, such as an iron pen, is used, and the top or bottom sheet is the support. A case where both sides are self-coloring layers is shown. The layer structure of the self-coloring layer may be a two-layer structure or a single-layer structure as described above, but the layer structure of the intermediate support can be changed depending on the type of color developer used. Don't be limited by this diagram.

Although one example of the present invention has been shown above, the embodiments of the present invention are not limited to these.
However, in general, from the viewpoint of manufacturing costs, etc., when coating a capsule layer on the surface that contacts the self-coloring layer, as shown in Figure 5, it is necessary to reduce the amount of expensive coloring agent.
or is preferably removed, more preferably,
As shown in FIG. 3, FIG. 4, or FIG. 6, it is preferable to provide a coating layer containing an inexpensive color developer as a main component on the surface in contact with the self-coloring layer. In addition, in order to color a large number of sheets at the same time, it is preferable to increase the amount of microcapsules and/or color developer applied, but in order to manufacture them at a lower cost, the strength of the microcapsules may be weakened. It is more preferable to destroy the microcapsules under low pressure so that high color density can be obtained even with a small amount of coating.

When using microcapsules that break at low pressure, if the self-coloring layer is mixed with a color developer as shown in Figure 2, the microcapsules will be broken during the manufacturing process, causing contamination. This is not preferable because it requires the use of a large amount of protective agent, which makes it more expensive.

Therefore, a more preferable configuration is one in which the layer containing microcapsules as the main component is located between the support and the layer containing the color developer as the main component, as shown in FIG. 3 or 6. can give. In such a layer structure, the developer layer and the support serve as a protective layer for the microcapsules, and in order to prevent the destruction of the microcapsules during the manufacturing process, the protective agent for the microcapsules can be reduced or removed. There are advantages.

Next, the present invention will be further explained by examples.

The coating liquid used in the examples was prepared as follows.

As wall film-forming substances, 5 parts of an adduct of 3 moles of tolylene diisocyanate and 1 mole of trimethylolpropane and 1 part of an adduct of sorbitol and propylene oxide are dissolved in 4 parts of ethyl acetate, and this is dissolved in 28 parts of diisopropylnaphthalene. to the department,
It was dissolved in an oily liquid containing 1 part of crystal violet lactone and 1 part of benzoylleucomethylene blue. (Oil-based liquid A) To prepare the protective colloid, dissolve 1.5 parts of carboxy-modified polyvinyl alcohol with a saponification degree of 85 mol% and a polymerization degree of 1725, which is obtained by modifying 5 mol% of polyvinyl alcohol with itaconic acid, in 20 parts of water. The temperature was 20°C. (Protective colloid A) For encapsulation, oily liquid A is gradually added to vigorously stirring protective colloid A to form an o/ω type emulsion, with an average oil drop size of 8 μm.
After adding more water and adjusting the concentration to 30%,
Raise the liquid temperature to 75℃ to promote the formation of a wall film,
After holding for 30 minutes, it was cooled to 25°C to obtain capsule liquid A. Color developer liquid A, color developer liquid B, and color developer liquid C were prepared as follows.

Color developer solution A was prepared by dissolving 7 parts of 50% sodium hydroxide in 200 parts of water, gradually adding 80 parts of acid clay while stirring vigorously, and then adding 19 parts of styrene-butadiene rubber latex and dodecylbenzenesulfonate. Obtained by adding 0.1 part of acid triethanolamine salt.

Color developer liquid B was obtained by adding 3 parts of zinc 3,5-di(α-methylbenzyl)salicylate and 7 parts of water to 306.1 parts of color developer liquid A with vigorous stirring.

In addition, color developer solution C consists of 200 parts of water and 65 parts of high quality clay.
10 parts of 5-di(α-methylbenzyl)salicylic acid,
After adding 5 parts of zinc chloride and treating with attritor, 21 parts of styrene-butadiene rubber latex,
It was obtained by adding 0.1 part of dodecylbenzenesulfonic acid triethanolamine salt.

The capsule liquid and developer liquid were applied by a curtain coating method, and the coating amounts were 4 g/m ² for the capsule liquid and 6 g/m ² for the developer liquid.

Example 1 Capsule liquid A and color developer liquid A were applied to one side of paper to obtain a sample (sheet A). Next, developer liquid B was applied to the surface of the paper, and after drying, capsule liquid A and color developer A were applied to the back side of the paper to obtain a sample (sheet B).

When 5 sheets of sheet B were stacked under the obtained sheet A in the combination shown in Figure 3 and pressed with a ballpoint pen, both the front and back of each sheet developed vivid colors.
It was possible to prevent tampering with multiple sheets.

Example 2 A sample was obtained in the same manner as in Example 1 using developer liquid C instead of developer liquid A.

When the obtained sample was written in the same manner as in Example 1, the color was clearly developed on both the front and back of the sample, and it was possible to prevent tampering with multiple sheets.

[Brief explanation of the drawing]

FIGS. 1 to 2 are cross-sectional views of the recording sheet of the present invention, and FIGS. 3 to 8 are cross-sectional views showing the layer structure of the recording sheet of the present invention. 1 is a support, 2 is a self-coloring layer coated with microcapsules containing a coloring agent and a color developer, 3 is a layer coated with microcapsules containing a coloring agent and/or a color developer, 4 is a coloring layer 5 is an adsorbent solid acid such as clay, 6 is a microcapsule containing an agent;
numeral 7 indicates a color developer that is compatible with the oil in which the color former is dissolved, numeral 7 indicates office supplies for pressurization, and numeral 8 indicates a portion colored by pressurization.

Claims (1)

[Scope of utility model registration request] A recording sheet A having a self-coloring layer coated with microcapsules containing a color former and a color developer on at least one side of a support, and microcapsules containing a color former on one side of the support and/or Alternatively, a tamper-proofing device coated with a color developer is characterized by a combination of microcapsules containing the color developer on the other side of the support and one or more recording sheets B coated with the color developer. Pressure-sensitive recording sheet.