JP2003291523A - Desensitizing ink for pressure-sensitive copy paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide desensitizing ink for pressure-sensitive copy paper excellent in printing workability and preventing the occurrence of misting. <P>SOLUTION: In the desensitizing ink for pressure-sensitive copy paper containing a pigment, a desensitizer, an organic solvent and a resin as essential components, the desensitizing ink contains 3-10 mass% of a white pigment with an oil absorption of 140-300 ml/100 g in an amount of 3-10 mass% with respect to the whole pigment as the pigment and has a tack value of 3-7 and a viscosity of 100-140 dPas. Preferably, the white pigment is at least one pigment selected from silicon dioxide, aluminum silicate, calcium carbonate and magnesium carbonate and has a mean particle size of 4.0 μm or less. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a desensitizing ink for pressure-sensitive copying paper, and more particularly to a desensitizing ink for pressure-sensitive copying paper which has excellent printing workability and prevents the occurrence of misting. It is a thing.

[0002]

2. Description of the Related Art Pressure-sensitive copying paper, also called carbonless paper, has been in practical use for a long time. This usually consists of top paper coated with microcapsules containing a solution of an electron-donating colorless dye and bottom paper coated with an electron-withdrawing color developer. The dye is released and reacts with the color developer on the lower sheet to develop a color, thereby forming a visible copy image. Further, by inserting an intermediate sheet having a shape that also serves as an upper sheet and a lower sheet between both sheets, more copied images can be obtained. If a layer of microcapsules containing a colorless dye solution and a layer of a color developer are laminated and coated on one surface of the support, pressure-sensitive coloring can be obtained even with a single sheet of paper. As described above, in the pressure-sensitive copying paper, the reaction between the electron-donating colorless dye and the electron-withdrawing developer is a basic element, and many proposals have been made in the past.

Known as colorless dyes are triphenylmethane type lactone dyes represented by crystal violet lactone, xanthenephthalide type lactone dyes, and the like, and as color developers, activated clays represented by acid clay and the like. , Novolac type polycondensation resins of substituted phenols represented by paraoctylphenol or paraphenylphenol and aldehydes such as formaldehyde, or aromatic carboxylic acids represented by 3,5-di-α-methylbenzylsalicylic acid zinc salt Metal salts, etc. are well known as being of practical level.

The desensitizing ink for pressure-sensitive copying paper has been used for the purpose of disabling color development by applying it to the above-mentioned color developer coating layer, that is, a portion where color development is not required. The desensitizing ink is manufactured mainly by a desensitizing agent for making the color of the pressure-sensitive copying paper uncolorable and a vehicle for dispersing the desensitizing agent.

In order to actually apply the desensitizing ink to the color-developing surface, it is necessary to improve the accuracy of repetitive work (improvement of registration), improve the surface quality of the application surface, improve the accuracy of the deposited amount, diversify the form design, For the purpose of improving work efficiency, various auxiliaries are added so as to be suitable for various printing methods (flexo, gravure printing, letterpress printing, offset printing, silk screen printing, etc.).

Among various printing methods, offset printing is widely used because of its high printing speed and excellent productivity. This is a method generally performed using an aluminum plate called a PS plate. In this PS plate, a photosensitive resin is coated on an aluminum plate, and the original is reproduced on the PS plate by exposing and developing through a film on which a printed original is marked.

Desensitizing ink adheres to the hydrophobic part of the PS plate,
A printed matter is created by being transferred to paper through a blanket, and on the contrary, water adheres to the hydrophilic portion of the PS plate, which has a function of preventing stains during printing.

In the offset printing using such a PS plate, high-speed printing is possible, but with the increase in speed, the occurrence of misting is a serious problem.

The desensitizing ink is usually composed mainly of a desensitizing agent, a pigment, an organic solvent, a resin and the like. this house,
The pigment is added to give the desensitizing ink a viscosity suitable for printing.

The cause of misting during high-speed printing is that the amount of resin and solvent in the desensitizing ink is too large, so that the spinnability of the ink is increased and the desensitizing ink film is torn between the rollers rotating at high speed. This is the phenomenon of desensitizing ink scattering. In the past, the type and amount of resin added to the desensitizing ink had been examined, but it was still insufficient.

[0011]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a desensitizing ink for pressure-sensitive copying paper which has excellent printing workability and prevents the occurrence of misting.

[0012]

As a result of intensive studies in view of the above, the present inventor has invented the desensitizing ink for pressure-sensitive copying paper of the present invention.

That is, the desensitizing ink for pressure-sensitive copying paper of the present invention is a desensitizing ink for pressure-sensitive copying paper which contains a pigment, a desensitizing agent, an organic solvent and a resin as essential components. A white pigment having an oil absorption of 140 to 300 ml / 100 g is contained as a pigment in an amount of 3 to 10% by mass with respect to all pigments, and a tack value is 3 to 7 and a viscosity is 100 to 140 dPa.
s.

In the present invention, the white pigment is characterized by being at least one selected from silicon dioxide, aluminum silicate, calcium carbonate and magnesium carbonate.

In the present invention, the white pigment preferably has an average particle size of 4.0 μ or less.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The desensitizing ink for pressure-sensitive copying paper of the present invention will be described in detail below. INDUSTRIAL APPLICABILITY The present invention is excellent in printing workability used for preventing color development of pressure-sensitive copying paper,
The present invention relates to a desensitizing ink for pressure-sensitive copying paper which prevents the occurrence of misting.

The present inventors have found that, in high-speed printing using the desensitizing ink for pressure-sensitive copying paper of the present invention, the tack value and viscosity of the desensitizing ink have a great influence as a cause of misting. It was

When the tack value of the desensitizing ink for pressure-sensitive copying paper of the present invention is in the range of 3 to 7, it is possible to prevent the occurrence of misting in high-speed printing, and in accordance with the tack value,
The viscosity of the desensitizing ink falls within the range of 100 to 140 dPas.

If the tack value of the desensitizing ink for pressure-sensitive copying paper is less than 3, the viscosity of the desensitizing ink is 100 dP.
Since it is less than as, the amount of the desensitizing ink attached during high-speed printing is insufficient, causing printing defects and causing misting.

On the other hand, if the tack value of the desensitizing ink for pressure-sensitive copying paper exceeds 7 and is large, printing defects will occur in high-speed printing due to the high tackiness of the desensitizing ink.
Therefore, it is in a state where there is no need to see the occurrence of misting.

In order to keep the tack value and viscosity of the desensitizing ink for pressure-sensitive copying paper of the present invention within a predetermined range, 140 to 3 out of the pigments contained in the desensitizing ink is used.
It can be adjusted by adding a white pigment having an oil absorption of 00 ml / 100 g to the desensitizing ink in an amount of 3 to 10% by mass. As the content of the white pigment is closer to 10% by mass, the tack value and the viscosity are also improved. The upper limit within the range of the invention is approached.

Here, when the content of the white pigment is less than 3% by mass, the tack value and viscosity of the desensitizing ink also show low values, and when high speed printing is performed using this desensitizing ink,
The occurrence of misting cannot be prevented.

On the other hand, when the content of the white pigment exceeds 10% by mass, the tack value and viscosity of the desensitizing ink are out of the range of the present invention, and the viscosity of the desensitizing ink becomes too high.
Desensitizing ink becomes impossible. Or even if the desensitized ink is made, when printing is performed, the ink does not disperse well on the kneading roller, or the phenomenon that it does not move from the ink fountain to the kneading roller occurs, and the amount of ink adhered decreases and it is good. It becomes impossible to obtain a good printed matter.

Regarding the oil absorption of the white pigment used in the present invention, the oil absorption is 140 to 300 ml / 100 g.
The oil absorption is 140 ml / 100
When it is less than g, good printing durability cannot be obtained because the amount of the solvent incorporated in the white pigment is small. In addition, since the amount of solvent freely present in the desensitizing ink is large, the desensitizing ink splits between the rollers when the desensitizing ink is kneaded on the kneading roller, and the desensitizing ink is fogged at that time. A phenomenon called “misting” occurs, which adversely affects the health of the printing operator and is not preferable.

On the other hand, if the oil absorption exceeds 300 ml / 100 g, the amount of the solvent incorporated in the white pigment becomes too large, and the fluidity of the desensitized ink is significantly reduced. If the fluidity of the desensitizing ink decreases, it causes the problem of ink depletion, which makes it difficult for the desensitizing ink to move from the ink fountain to the roller, and the amount of ink deposited will decrease, resulting in good printed matter. Will not be possible.

In the present invention, the tack value of the desensitizing ink for pressure-sensitive copying paper is such that a certain amount of the desensitizing ink is transferred from a printing roll to a printing surface in high-speed printing using a printing machine such as a foam printing machine. It is the adhesion balance between the rotating printing roll and the surface to be printed when the printing is performed.

In measuring the tack value of the desensitizing ink for pressure-sensitive copying paper in the present invention, for example, an "Incomer" manufactured by Toyo Seiki Co., Ltd. is used, and the desensitizing ink is fixed at a constant amount between the metal roll and the rubber roll. It is a value obtained by measuring the force applied to the roll when rotated,
There is no unit.

The oil absorption of the white pigment used in the present invention is the oil absorption measured by the method defined in JIS K5101.

In the present invention, as the white pigment having a predetermined oil absorption amount, silicon dioxide, aluminum silicate,
At least one selected from calcium carbonate and magnesium carbonate is preferable, and silicon dioxide is more preferable.

Further, with respect to the average particle diameter of the white pigment used in the present invention, the smaller the average particle diameter, the more uniform the desensitizing ink for pressure-sensitive copying paper of the present invention can be, and the contribution to the printing durability of the printing plate. The average particle diameter is 4 μm or less.

In the present invention, when desensitizing printing is performed on pressure-sensitive copying paper, color development tends to be obstructed as the ink adhesion amount is increased. However, if the ink adhesion amount increases too much, poor drying occurs in the printing process, which causes stains such as guide roll stains, making it impossible to obtain good printed matter.

Since the pressure-sensitive copying paper is used as a continuous form paper, a processing called fan hold processing is performed. This is a process in which the printed matter is continuously folded after the printing and slitting processes are completed. However, if a drying defect occurs, the problem of set-off defect occurs in which the ink is transferred to the opposite side. Therefore, the range of the amount of the desensitized ink attached must be such that color development can be properly inhibited and defective drying does not occur. Generally, the amount of desensitizing ink attached at this time is about 1.0 to 3.0 g.
/ m ^2, the desensitizing ink film pressure at this time is about 5 μm.
It is estimated to be about. Therefore, if the average particle size of the white pigment contained in the ink is set to 4 μm or less, it can be said to be a preferable mode because it leads to improvement of the quality of the printed surface.

In the present invention, the desensitizing agent constituting the desensitizing ink for pressure-sensitive copying paper is an electron-donating, colorless organic compound having a proton-accepting property, a so-called color-forming agent and a solid acid having an electron-accepting property or a proton-releasing property. It has the function of reducing or eliminating the reaction that is initiated by contact with a so-called color developer. Regarding the desensitizer, U.S. Pat. No. 2,777,780, JP-B-44-27255,
45-21448, 46-22651, 46
-29546, JP-A-7-32915, and JP-B-47.
Although detailed in each publication such as -38201 and 48-4050, the following specific examples can be given, for example. Quaternary ammonium salts such as dodecyltrimethylammonium chloride and octadodecylammonium chloride, high molecular weight amines such as dodecylamine: Substituted oxazolines such as 2,4,4-trimethyl-2-oxazoline: xylenediamine, N-aminopropylpiperazine A reaction product of a diamine or polyamine derivative having a cyclic structure in the molecule with an alkylene oxide: polyoxyethylene alkylamine, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether polyethylene glycol polypropylene glycol, polyoxypropylene alkylamine, Polymers having a glutamic acid-r-alkyl ester residue, spiroacetal-based diamines, N- (aminoalkyl) -lactams, Glycidyl ether adducts of amine compounds and the like.

The vehicle serves to disperse the pigment to give fluidity to the ink and fix the pigment and the like at the time of printing. Usually, the vehicle is composed of a solvent and / or a resin, and vegetable oil, mineral oil, cooked flaxseed oil or alkyd is used. resin,
Maleic acid resin, rosin-modified maleic acid resin, phenol resin, rosin-modified phenol resin, vinyl resin, ketone resin, polyamide resin, urea resin, melamine resin and the like are used. Further, an ultraviolet curable desensitizing ink can be prepared by using a general ultraviolet curable vehicle. The UV-curable vehicle is a compound having an unsaturated bond, that is, an ester of a polyhydric alcohol such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, glycerin or trimethylolpropane, and acrylic acid or methacrylic acid. , Glycidyl ether terminal epoxy acrylates, methacrylates, these monomers, dimers,
Trimers and oligomers (prepolymers) are mainly used, and unsaturated alkyd resins, non-drying oils, oil-modified alkyd resins, arylsulfonamide / formalin resins, epoxy resins, urea / formalin resins, to give film forming ability. A diaryl phthalate resin or the like may be added. As an additive, a photoinitiator, a chain transfer agent, a stabilizer, a fluidity improving agent, a wax agent, etc. can be added.

As the organic solvent, hexane, heptane,
Benzene, toluene, benzene, toluene, xylene,
Ethyl acetate, methyl ethyl ketone, ethanol, methanol, propanol, paraffinic high boiling point solvent, paraffinic low boiling point solvent, linseed oil, tung oil, soybean oil, cottonseed oil and the like can be used.

By applying a UV-curable ink vehicle in the desensitizing ink, it can be made into a UV-curable desensitizing ink, and especially in letterpress or offset printing, ink drying can be accelerated, printing speed can be increased, and ink can be dried. Effects such as prevention can be achieved.

The pigment mainly adjusts the viscosity of the desensitizing ink,
It is added to give opacity and concealment to the printed area.
Examples include titanium oxide, barium sulfate, barium carbonate, talc, kaolin, zinc oxide, calcium carbonate, inorganic pigments such as bentonite, styrene-acrylic copolymer resins, organic pigments such as polystyrene, but whiteness and hiding power. It is preferable to use titanium oxide. Further, this titanium oxide can be used in either rutile type or anatase type.

As an additive, a desiccant, an anti-settling agent, an antioxidant, paraffin wax, or carnauba wax may be used as required.

[0039]

EXAMPLES The following examples and comparative examples show misting and printing workability when printing was performed using the desensitizing ink for pressure-sensitive copying paper of the present invention. Further, “parts” and “%” shown in the examples represent parts by mass and% by mass, unless otherwise specified. The present invention is not limited to the embodiments.

Prior to the Examples and Comparative Examples, the properties of the desensitizing inks for pressure-sensitive copying paper produced were measured by the following methods. <Tack value> The tack value is obtained by measuring the force applied to the rolls when an appropriate amount of desensitizing ink is applied between the metal roll and the rubber roll and rotated for a certain period using an "Incometer" manufactured by Toyo Seiki Co., Ltd. It means that the larger the value, the higher the tackiness.

<Oil Absorption> Regarding the oil absorption of the white pigment,
Although it is the oil absorption amount measured by the method specified in JIS K5101, the value displayed by the manufacturer was used in the examples. The unit is ml / 100g.

<Viscosity> The viscosity was measured using an L-type viscometer manufactured by Toyo Seiki. The unit is dPas.

Various conditions when printing is performed using the desensitizing ink for pressure-sensitive copying paper according to Examples and Comparative Examples are shown below. <Printing speed> 150 m / min <Paper used for printing> Mitsubishi NCR paper Super N40 Lower paper Mitsubishi Paper Mills <Moisturizing liquid> 5% IPA-0.2% SEVENSTAR (Dainichi Seika) <Printing plate used> FNS-A 0.24 mm (manufactured by Fuji Photo Film Co., Ltd.) <Printing machine> Form printing machine; MVF-18D (manufactured by Miyakoshi Co., Ltd.)

The method for evaluating the misting and printing workability when printing the desensitizing ink for pressure-sensitive copying paper is shown below.

<Misting> Under the following conditions, a transparent film was placed about 5 cm away from the roll, and the amount of misting scattered was visually determined. Here, ∘ indicates that the misting did not occur, ∘ indicates that the misting occurred but was extremely small, Δ indicates that the misting occurred but was within the allowable range, and x indicates that the most occurred. The allowable range is Δ.・ Ink calling time: 150 seconds ・ Mixing roll speed: 350 rpm ・ Ink fountain opening: 5 ・ Ink fountain opening: 45 ・ Measuring time: 5 minutes

<Printing Workability> When the desensitizing ink fountain did not die during printing under the above conditions, it was marked with ◯, and when it occurred, it was marked with x. The allowable range is ○.

Example 1 The desensitizing ink for pressure-sensitive copying paper of Example 1 was prepared with the following composition. Desensitizer: Polyoxyalkylene propylene diamine 50 parts Resin: Rosin modified phenol resin 20 parts Pigment: Titanium dioxide 24 parts White pigment: Amorphous silica (Mizukasil P-78A manufactured by Mizusawa Chemical Industry Co., Ltd.) 6 parts It was used. The white pigment has an average particle size of 3.0 μm and an oil absorption of 246 ml / 100 g. In producing a desensitizing ink for pressure-sensitive copying paper, first, dissolve the resin in the desensitizing agent, add titanium dioxide and amorphous silica, and knead with a three-roll mill to make the desensitizing ink. A desensitizing ink for pressure-sensitive copying paper of Example 1 was obtained.

Examples 2 to 6 and Comparative Examples 1 to 3 Examples 2 to 5 and Comparative Examples were carried out in the same manner as in Example 1 except that the white pigments used in Example 1 were replaced with the white pigments listed in Table 1. Desensitizing inks for pressure sensitive copying paper of Nos. 1 to 3 were prepared. The average particle size and oil absorption of the white pigment used are also listed in Table 1.

Examples 7 to 8 and Comparative Examples 4 to 5 Examples except that the contents of titanium dioxide (pigment) and amorphous silica (white pigment) of Example 1 were changed to those shown in Table 1. In the same manner as in Example 1, desensitizing inks for pressure-sensitive copying paper of Examples 7 to 8 and Comparative Examples 4 to 5 were prepared.

Using the desensitizing inks for pressure-sensitive copying paper prepared in Examples 1 to 8 and Comparative Examples 1 to 5, the tack value and the viscosity were measured by the above-described measuring method, and further printed by a printing machine. , Evaluated by the evaluation method described above,
The results are shown in Table 1.

[0051]

[Table 1]

Evaluation: As is clear from the above-mentioned Examples and Comparative Examples, the oil absorption of the white pigment in the present invention is 140-.
When it is within the range of 300 ml / 100 g, and when the white pigment is 3 to 10% by mass in all the pigments, it can be adjusted so that the tack value and the viscosity of the desensitizing ink for pressure-sensitive copying paper are within the specified range. When this was used for printing, the occurrence of misting could be prevented, and the print workability was also good. On the other hand, in the desensitizing ink for pressure-sensitive copying paper of Comparative Example 3 in which the oil absorption of the white pigment is high and Comparative Example 5 in which the content of the white pigment is high, the defective value of the desensitizing ink causes a printing failure due to its high tack value and viscosity. There was no need to wake up and see the occurrence of misting. Further, in the desensitizing inks for pressure-sensitive copying papers of Comparative Examples 1 and 2 in which the oil absorption of the white pigment is small and Comparative Example 4 in which the content of the white pigment is small, the tack value and the viscosity are low values outside the specified ranges. And as a result,
The occurrence of misting was extremely high.

[0053]

As described above, the desensitizing ink for pressure-sensitive copying paper of the present invention defines the tack value and viscosity of the desensitizing ink,
By using a specific white pigment in the pigment for adjusting this, the printing workability in high-speed printing is excellent and the occurrence of misting phenomenon can be prevented.

Claims (3)

[Claims] 1. A desensitizing ink for pressure-sensitive copying paper, which comprises a pigment, a desensitizer, an organic solvent and a resin as essential components, wherein the desensitizing ink is a white color having an oil absorption of 140 to 300 ml / 100 g as the pigment. 3 to 10% by mass of pigment based on all pigments
Must contain, tack value 3-7, viscosity 100-14
A desensitizing ink for pressure-sensitive copying paper, which is characterized by having 0 dPas. 2. The desensitizing ink for pressure-sensitive copying paper according to claim 1, wherein the white pigment is at least one selected from silicon dioxide, aluminum silicate, calcium carbonate and magnesium carbonate. 3. The desensitizing ink for pressure-sensitive copying paper according to claim 1, wherein the white pigment has an average particle diameter of 4.0 μm or less.