JPH02233285A - Desensitizing ink for pressure-sensitive copying paper - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a desensitizing ink for pressure-sensitive copying paper,
In particular, the present invention relates to a desensitizing ink for pressure-sensitive copying paper that has excellent set-off properties, excellent desensitizing effects, and printability.

(Prior art) Electron-donating or proton-accepting colorless organic compounds (
It has been known for a long time that a colored image is obtained by a reaction between an electron-accepting or proton-releasing substance (hereinafter referred to as a color developer) and an electron-accepting or proton-releasing substance (hereinafter referred to as a color developer).

Pressure-sensitive copying paper (
For example, US Patent No. 2505470, US Patent No. 250489,
No. 2550471, No. 254836, No. 27125
No. 07, No. 2730456, No. 2730457, No. 3
418250, 362935), heat-sensitive recording paper, such as Tokko No. 43-4 160, 41-7600.
No. 4514039, U.S. Patent No. 2939009)
Examples include. Furthermore, a printing method is also known in which a colored image is obtained by supplying ink containing a color former to a sheet coated with a color developer (German patent (○LS) No. 1939962).
.

Color developers have the properties described above, and include clays,
Examples include phenolic resins and metal salts of aromatic carboxylic acids.

Generally, in pressure-sensitive copying paper, a combination of a layer containing microcapsules containing the above-mentioned color former and a color developer layer is used to obtain a colored image, and the microcapsules are destroyed by typing pressure, etc., and the color former is removed. Image formation is performed by contacting the color developer. Generally, these color developers are used as a color developer sheet that is uniformly applied to the entire surface of the support, but depending on the purpose of use of the pressure-sensitive copying paper, there may be some areas where recording is not necessary, so it is necessary to Another method is to apply desensitizing ink to that part of the color developer sheet using a printing machine or the like to make it impossible to develop color.

Regarding desensitizing inks used for such purposes, for example, U.S. Pat.
No. 5, No. 45-21448, No. 46-22651,
No. 47-38201, No. 48-4050, No. 41-
No. 4484, No. 40-19647, No. 49-2300
No. 8, No. 49-23850, Japanese Unexamined Patent Publication No. 4'1-3291
No. 5, No. 48-6805, No. 49-43708, No. 4-72009, No. 49-77709, No. 49-
No. 77710, No. 49-15513, No. 49-835
No. 09, German patent (OLS) No. 2343800, same 2
No. 359079, No. 2361856, No. 6B-411
84, No. 63-74681, etc.

(Problem to be solved by the invention) The desensitizing ink for pressure-sensitive copying paper used for the above purpose generally contains a desensitizer, a pigment, and a binder (various ink resins) as essential components. Depending on the situation, an organic solvent or the like may be added to form a composition. However, with conventional desensitizing inks, the ink in printed areas is transferred to non-printed areas over time, causing decolorization and fading in areas that are not intended to be desensitized, that is, a set-off phenomenon often occurs. Ta.

As a means to solve this set-1-off phenomenon, methods of improving desensitizers and binders have been proposed. In other words, the former method involves controlling the structural formula and molecular weight of the desensitizer in the ink so that it does not diffuse, and the latter method involves selecting a desensitizer that can easily penetrate into paper waste and set easily. However, in the former case, the desensitization effect is considerably reduced, and in the latter case, good ink spread and transfer on the printing press are hindered, resulting in poor set-off properties, desensitization properties, and on-machine stability. At present, an ink that fully satisfies all the characteristics has not been obtained.

An object of the present invention is to provide an excellent desensitizing ink for pressure-sensitive copying paper that has an excellent balance between set-off properties and desensitizing effects, and that does not cause any problem in stable running on a printing press.

(Means for Solving the Problem) It has been found that the above object can be achieved by the means described below. That is, in a desensitizing ink containing a desensitizer, a pigment, and a binder as essential components, the average Fine particles with a particle size of 2 to 25 μm are added to the entire ink.
It is to be contained in a range of 1 to 20 parts per part by weight.

The average particle size mentioned here refers to the volume average particle size of a primary particle (single particle), and refers to a particle size calculated by various measurement methods using a commercially available optical or electrical particle size measuring device, an electron microscope, or the like.

Specific examples of the fine particles used in the present invention include various starch particles such as wheat starch, corn starch, and horse starch; Preferred examples include polymeric microspheres such as polymeric microspheres such as polymers and methacrylic acid copolymers; and inorganic particles such as synthetic silica and semi-synthetic silica. If the average particle size is smaller than the above range, the object of the present invention will not be fully achieved, and if it is larger than this range, the fine particles will be easily destroyed during ink preparation, resulting in unevenness of the desensitized printed surface, roughness, etc., resulting in poor quality. Not good.

Usually, white pigments such as titanium dioxide, barium sulfate, barium carbonate, talc, kaolin, bentonite, etc. are used as pigments for desensitizing inks, but the pigments are usually microparticles in the so-called submicron region of 1 μm or less, It is clearly distinguishable from the fine particles used in the present invention, which have an average particle size of 2 to 25 μm.

The content of fine particles in the present invention is in 100 parts of ink]
~20 parts is preferred. If the amount is less than this range, the effect of the present invention will be insufficient, and if it is too much, the desensitizing effect will decrease, which is not preferable.

Desensitizers used in the present invention include quaternary ammonium salts such as dodecyltrimethylammonium chloride and octadecyl ammonium chloride, addition reaction products of polyamine derivatives and alkylene oxides, polyoxyethylene alkyl amines, polyoxyethylene alkyl ethers, Examples include polyoxyethylene alkyl phenyl ether, polyethylene glycol, polypropylene glycol, polyoxypropylene alkylamine, and the like.

The binder used in the present invention includes rosin-modified maleic acid resin, rosin-modified phenol resin, ketone resin,
Polyamide resin, maleic acid resin, phenolic resin, epoxy resin, alkyd resin, melamine resin, urea resin,
Natural or synthetic polymeric compounds such as nitrocellulose, ethylcellulose, butyral resin, polyvinyl alcohol, gelatin, and shellac are used.

The desensitizing ink of the present invention can be sufficiently used as a composition containing only the above-mentioned essential components and containing fine particles, but if necessary, an organic solvent may be added as a diluent. Examples of organic solvents include linseed oil, tung oil, soybean oil, cottonseed oil, methanol, ethanol, ethyl acetate,
Examples include toluene, hexane, methyl ethyl ketone, methyl isobutyl ketone, polypropylene glycol, polybutylene glycol, paraffin oil, etc.

Furthermore, waxes such as paraffin wax, carnauba wax, and microcrystalline wax, ultraviolet absorbers, antioxidants, and the like may be added as necessary.

The desensitizing ink of the present invention is prepared by mixing, dissolving, or, if necessary, kneading the above-mentioned components using a 21-goo, a 3-roller, or the like.

The desensitizing ink of the present invention is suitable for flexographic printing, letterpress printing,
Printing is applied to developing sheets using various printing machines, including those for offset printing.

The application amount of the desensitizing ink was 01 to I Cl. Og/m
', preferably in the range of 0.5 to 3.0 g/nf.

=7- Specific examples of color developing sheets to which the desensitizing ink of the present invention is effectively applied include clays (e.g. acid clay, activated clay), novolak type phenol aldehyde resin, aromatic carboxylic acid metals. It contains salts as an active ingredient, and is not particularly limited.

(Example) Next, an example of the present invention will be shown. All parts listed are dry weight parts.

Example-1 To a mixed solvent of 9 parts of No. 00 linseed oil and 9 parts of white spindle oil, 18 parts of rosin-modified phenol resin (manufactured by Arakawa Chemical Co., Ltd., Tamanol T-361) was added, and 17
After completely dissolving at 0° C., 42 parts of an ethylenediamine-butylene oxide 12 molecule adduct was added as a desensitizer and mixed thoroughly to obtain a desensitizing ink face.

After cooling this face to about 50°C, titanium dioxide (Tipaque CR-93 manufactured by Ishihara Sangyo Co., Ltd., average particle size 0.
29 μm> 15 parts, 7 parts of wheat starch (manufactured by Okumoto Seifun ■, Kogyo Toku etc., average grain = 8 - diameter 18 μm) as the fine granules of the present invention were added, and kneaded with three rollers to be used for offset printing and letterpress printing. A desensitizing ink was obtained.

Example-2 Cross-linked polystyrene microbeads (manufactured by Sumitomo Chemical Co., Ltd., Fine Pearl PB) were used instead of 7 parts of wheat starch in Example-1.
-3006E, average particle size 6 μm) 12 parts and 10 parts of titanium dioxide were used instead of 15 parts.
A desensitizing ink was prepared in the same manner.

Example-3 In place of 7 parts of wheat starch in Example-1, synthetic silicate particles (
Manufactured by Mizusawa Chemical Industry ■, Silton AM-35, average particle size 3
．． A desensitizing ink was prepared in the same manner as in Example 1, except that 7 parts were used instead of 15 parts of titanium dioxide and 15 parts of titanium dioxide.

Example-4 In place of 7 parts of wheat starch in Example-1, 3 parts of polyethylene particles (manufactured by Tetsutsu Kagaku ■, Flow Beads HE-5023, average particle size 2 μm) were used, and in place of 15 parts of titanium dioxide, 19 parts were used.
A desensitizing ink was prepared in the same manner as in Example 1 except that

After printing with the inks of Examples 1 to 4 using an offset printing machine, the printed surface was observed using a scanning electron microscope.
It was clearly confirmed that pigment particles in an amount corresponding to the initial addition amount were printed uniformly while retaining their original shape.

Comparative Example 1 A desensitized ink was obtained in the same manner as in Example 1 except that 22 parts of titanium dioxide was added instead of the wheat starch used in Example 1.

Comparative Example-2 Without adding titanium dioxide as a pigment in Example-2,
A desensitized ink was obtained in the same manner except that 22 parts of cross-linked polymethyl methacrylate beads (Fine Pearl PM-3030 manufactured by Sumitomo Chemical Co., Ltd.) having an average particle size of 30 μm were used as fine particles.

Comparative Example-3 15 parts of calcium carbonate with an average particle size of 3.3 μm as fine particles (calcium carbonate manufactured by Shiroishi Central Laboratory, Karly}-SA, aggregates of calcium carbonate with a primary particle size of less than 1 μm), and titanium dioxide as a pigment. A desensitizing ink was prepared in the same manner as in Example-1 using 7 parts.

The ink evaluation results were obtained by printing the above desensitized ink on a developer sheet using an offset printing machine at a coating amount of 1.5 g/m', and then printing the same desensitized ink on an unprinted developer sheet After applying a load of 100 g/c for one week, the degree of transfer (set-off) and desensitization effect to the unprinted color developer sheet 1 were determined on each sheet and on commercially available pressure-sensitive copying paper. The evaluation was made by putting the paper over the paper and passing it through a super calendar to develop color on the entire surface. The evaluation results are shown in Table 1.

(Hereinafter in the margin) 11- (Effects of the Invention) The desensitizing ink of the present invention has excellent set-off properties while maintaining excellent desensitizing effects and printability, and is therefore very practical.

Claims (1)

[Claims] In a desensitizing ink for pressure-sensitive copying paper containing a desensitizer, a pigment, and a binder as essential components, fine particles with an average particle size of 2 to 25 μm are added to 100 parts by weight of the ink.
1. A desensitizing ink for pressure-sensitive copying paper, characterized in that the desensitizing ink is contained in an amount ranging from 20 parts to 20 parts.