JPS6341753B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to desensitizers. More specifically, the present invention relates to a desensitizer for suppressing or blocking the coloring function of carbonless pressure-sensitive copying paper using an electron-accepting compound or solid acid for coloring a colorless coloring agent. Generally, pressure-sensitive copying paper consists of paper coated with an electron-donating leuco dye encapsulated in fine capsules and paper coated with an electron-accepting substance or solid acid. When pressurized, the capsule in the pressurized area is destroyed and the leuco dye develops color. The desensitizer is used for the purpose of suppressing or preventing color development by applying it in advance to areas where color development is unnecessary on either the surface coated with the electron-accepting substance or the electron-donating substance. Capsules containing electron-accepting substances and electron-donating substances are uniformly applied to the entire surface of the paper, so it is widely used to apply a desensitizer to either side of the paper using a printing machine to remove unnecessary areas. It is. Clay minerals such as acid clay, bentonite, attapulgite, zeolite, and kaolin are known as electron-accepting solid acids. Also, known electron-donating color formers include crystal violet lactone, rhodamine anilinolactone, malachite green lactone, benzoyl leucomethylene blue, Michler's hydrol, and N-allyl leuco auramine. Conventionally known desensitizers include Japanese Patent Publication No. 46-29546;
Polyhydroxy compounds such as those found in Japanese Patent Publication No. 49-19647, Japanese Patent Publication No. 48-6805, etc., Japanese Patent Publication No. 44-27255,
Amine-related compounds such as those found in Japanese Patent Publication No. 45-21448, hetero compounds such as those found in Japanese Patent Publication No. 33-3921 and Japanese Patent Publication No. 15513-1973, and Japanese Patent Publication No. 52-1989
There are polyether compounds as seen in 156010 and JP-A-53-97511. Most of these desensitizers are strongly hydrophilic substances and are therefore printed by letterpress printing presses.
It was difficult to use printing machines other than letterpress printing machines. The ability to print desensitizers on printing presses other than letterpress printing presses provides various advantages. For example, if it became possible to print with an offset lithographic printing machine, compared to printing with a conventional letterpress printing machine, (1) the ink would be evenly distributed because it is offset, and (2) the printing pressure would be applied to the entire surface of the plate. Because it applies evenly, there is less destruction of paper microcapsules (3) Plate making is easy (4) Printing speed is high (5) Printing has a beautiful finish (6) Printing machines are widely used by the general public Therefore, advantages such as high demand can be expected. Attempts have been made to print desensitizers using wet offset printing machines, for example, using alkoxyl nucleophilic compounds as desensitizers, but conventional desensitizers have poor printability and bleed resistance, and The desensitization effect was also not sufficient. Although attempts have recently been made to print desensitizers by waterless lithographic printing, there has been a strong desire for a desensitizer that can be printed using conventional wet offset printing machines. As a result of intensive research into desensitizers that can be printed not only on letterpress printing machines but also on printing machines other than letterpress printing machines, the present inventors came to invent the desensitizer with excellent desensitizing effects of the present invention. It is something. That is, the desensitizer of the present invention is a desensitizer comprising a product obtained by addition-reacting (1) rosin or modified rosin having a carboxyl group and (2) alkylene oxide. The present invention has an excellent desensitizing effect on pressure-sensitive copying paper such as carbonless copying paper, and there is no bleeding of desensitizer into unprinted areas, and the present invention is applicable to printing methods other than letterpress printing as well as letterpress printing. In particular, it has excellent printability during wet offset printing, and does not have the problems of yellowing and odor that are the drawbacks of conventional desensitizers.
The present invention provides a desensitizer that is easy to synthesize. The printing ink using the desensitizer according to the present invention can be printed by various printing methods such as offset printing and flexographic printing in addition to conventional letterpress printing.
It has various advantages not available with conventional desensitized inks for letterpress printing. For example, when a printing ink made using the desensitizer according to the present invention is printed using a wet offset printing machine, the printing effect and drying properties are excellent, so printing can be performed at high speed. Plate making is also easy and can save a lot of labor. When printed with an ink prepared using the desensitizer according to the present invention, a printed matter with good writability and inconspicuous printing can be obtained. The rosin or modified rosin having a carboxyl group according to the present invention is a rosin that is a natural resin, or a rosin that has been modified using the carboxyl group or double bond of a resin acid that is the main component of the rosin, and is a natural resin. Rosin is a resin acid whose main component is abietic acid. Modified rosins with carboxyl groups include polymerized rosin, disproportionated rosin, hydrogenated rosin, oxidized rosin, maleic acid resin, fumaric acid resin, and rosin-modified phenol. There are resins, etc. Among these rosins or modified rosins, resins with a relatively high acid value are preferred from the viewpoint of desensitizing effects, such as rosin, hydrogenated rosin, polymerized rosin, and maleic acid resin (reaction product of rosin and maleic acid). Particularly preferred are fumaric acid resins (reaction products of rosin and fumaric acid). Any alkylene oxide may be used in the present invention, but ethylene oxide, propylene oxide, or a mixture thereof is preferred from the viewpoint of desensitizing effect. The number of moles of alkylene oxide added is rosin,
In the case of hydrogenated rosin, polymerized rosin, disproportionated rosin, etc., 5 to 100
Moles are preferred. When the number of moles added is 100 moles or more, the drying property after printing tends to be poor, and when the number of moles added is 5 moles or less, the desensitizing effect tends to be poor. The present invention will be explained below with reference to Examples and Comparative Examples. Example 1 50 parts by weight of ethylene oxide adduct of rosin (number of moles of ethylene oxide added per equivalent of carboxyl group of rosin: average 30 moles), 40 parts by weight of titanium white (rutile) and 10 parts by weight of mineral oil were mixed in a three-roller mill. A desensitized ink was prepared by uniformly kneading the mixture. By the same method as in Example 1, instead of the ethylene oxide adduct of rosin, the following composition was used:
A desensitizing ink was prepared using the rosin obtained by the reaction or an adduct of a modified rosin having a carboxyl group and an alkylene oxide.

[Creation of printed matter]

The desensitizing inks obtained in Examples 1 to 8 and Comparative Examples 1 and 2 were applied in an amount of 5.0 g each to inner sheets of commercially available carbonless pressure-sensitive copying paper using an offset printing tester. / ^m2 . Next, test methods for desensitization effect, bleed resistance, and printability will be shown. [Test method] Desensitization effect test Using the above printing paper, 100
The desensitizing effect was tested by copying (coloring) by applying a load of 100 g and moving at a speed of 5 m/min. The test results are shown in Table 1.
The numerical value is the reflected visual density value (visual density abbreviation: Vis, D) measured with a microdensitometer.
shows.

[Table] Bleed resistance test The above printed material and non-desensitized carbonless pressure-sensitive copying paper were stacked together, a load of 10 g/cm ² was applied, and the paper was placed in a constant temperature and humidity room at a relative humidity of 90% and a temperature of 20°C. After being left for one month, the printed matter and the non-desensitized carbonless pressure-sensitive copying paper were subjected to a coloring operation to test their bleed resistance. The results are shown in Table 2.

[Table] Offset printing suitability test Regarding offset printing suitability, the ease of printing using an offset printing tester was comprehensively judged. The results are shown in Table 3.

[Creation of printed matter]

The desensitized inks obtained in Examples 9 and 10 and Comparative Example were applied to inner sheets of commercially available carbonless pressure-sensitive copying paper using a flexographic printing tester at a coating amount of 4.0 g/m ² respectively. I printed it like this. [Test Method] Using the obtained printed paper, the desensitization effect and bleed resistance were tested by the same method as that used in Examples 1 to 8 and Comparative Examples 1 and 2. Regarding suitability for flexographic printing,
The ease of printing was comprehensively judged using a flexographic printing tester. The results of the desensitization effect test are shown in Table 4, the results of the bleed resistance test are shown in Table 5, and the results of the flexo printing aptitude test are shown in Table 6.

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[Table] ○: Good △: Slightly poor
The results shown in Tables 1 to 6 show that the desensitizer according to the present invention is excellent in desensitizing effect, bleed resistance, suitability for offset printing, and suitability for flexographic printing.

Claims (1)

[Claims] 1. A desensitizer comprising a product obtained by addition reaction of (1) rosin or modified rosin having a carboxyl group and (2) alkylene oxide.