JP2006298948A - Waterless lithographic printing ink composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waterless lithographic printing ink composition capable of improving resistance to peeling of paper and an impression property and excellent in gloss, fluidity and resistance to greasing in order to correspond to speeding-up of printing in waterless lithographic printing and lowering of quality of paper used. <P>SOLUTION: The waterless lithographic printing ink composition comprises a perfluoropolyether oil having 500-20,000 weight-average molecular weight and as necessary, a resin alone or a plurality of resins selected from a rosin-modified phenol resin, an alkyd resin and a petroleum resin as a binder resin. An environment-conscious type ink can be obtained by preparing the above ink composition not containing mineral oils as a solvent component. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention responds to high-speed printing in waterless lithographic printing that does not require fountain solution and lowering of the paper used, and therefore has excellent fluidity, paper-peeling resistance, fleshing property, gloss, and soiling. A waterless lithographic printing ink composition having excellent resistance is provided.

Lithographic printing, which is the mainstream of commercial printing, is formed by supplying dampening water to a non-image area and forming an image area and a non-image area by utilizing the ink repulsion property. However, this lithographic printing method is largely caused by fountain solution and emulsification of fountain solution and ink. To control it, a great deal of equipment, consumables, time and skill are required. It was.

In recent years, a waterless lithographic printing method has been proposed as a method for solving this problem related to fountain solution. In particular, printing is performed by providing silicone rubber on the non-image area in order to show ink repellency instead of fountain solution. The method has been put into practical use. In such waterless lithographic printing, it is known that printing with a conventional oil-based ink is not preferable because sufficient ink repulsion at a non-image area cannot be obtained, and background staining occurs. The phenomenon of scumming in waterless printing is due to the temperature rise caused by friction of the drive unit and rollers of the printing press during printing, and because the dampening solution is not used, the effect of cooling the printing plate due to water evaporation is lost. As the temperature rises, the cohesive strength of the ink itself decreases, and the ink adheres to the non-image area where the ink should repel the ink, so that a normal printed image cannot be obtained.

In order to solve this problem peculiar to waterless printing, for example, the resin in the ink vehicle component is made high molecular weight to increase the cohesive force (Japanese Patent Laid-Open No. 05-279613), and a thickener is used (Japanese Patent Laid-Open No. 06-157960). No.), silicone modified resins and organopolysiloxanes (Japanese Patent Laid-Open No. 50-71410) have been used to reduce adhesion energy, and organopolysiloxanes, olefin polymers and diene polymers have been used to improve soil resistance. .
JP 05-279613 A Japanese Patent Laid-Open No. 06-157960 JP 50-71410 A JP 2002-97398 A

Higher molecular weight resin can be used to increase cohesion and thickeners can be used to obtain high-viscosity ink, which can improve scumming resistance, but transfer between ink rollers during printing, printing There was a problem that printability such as stability on the machine deteriorated.

In addition, the method of adding silicone oil has been practiced since the past and is effective in improving stain resistance. However, there are deteriorations in gloss and inking properties, and volatilization in dryers by off-wheel printing. As a result, it becomes a catalyst poison of the catalyst deodorizing apparatus, and its application has been limited. Silicone oil is very poorly compatible with the ink components and is easily separated, which often results in poor stability on the printing press. There is a problem that the stability on the printing press is insufficient, such as no longer sticking.

In addition to silicone oils, diene polymers and olefin polymers may exhibit scumming resistance depending on the molecular weight range, but the ink becomes hard due to poor compatibility with the vehicle, resulting in fluidity, wearability, and transferability.・ It was not of satisfactory quality due to limited glossiness and non-heat printing.

Waterless lithographic printing has been remarkably popular in recent years, but because of the increasing speed of printing and the use of low-grade paper such as recycled paper, ink for imparting paper resistance There is an ever-increasing demand for lowering the tackiness and improving the fleshing property on paper. Further, since waterless printing is also being performed on the additional paper, there is a demand for lower ink tack and improved fillability than ever before. In order to improve the resistance to paper peeling and the inking property, it is sufficient to increase the amount of the solvent in the ink. However, the adverse effect is that the viscosity is lowered and the stain resistance is deteriorated. There are demands for difficult issues such as providing soil resistance, reducing tackiness, improving wearability and improving the quality of all printed materials such as gloss.

The problem to be solved by the present invention is to provide a waterless lithographic printing ink composition which is improved in paper resistance, inking property, transferability, fluidity and gloss and excellent in stain resistance.

That is, the present invention relates to a waterless lithographic printing ink composition comprising a perfluoropolyether oil.

The present invention also relates to the waterless lithographic printing ink composition described above, wherein the perfluoropolyether oil has a weight average molecular weight of 500 to 20,000.

Furthermore, the present invention relates to the waterless lithographic printing ink composition described above, which contains one or more resins selected from rosin-modified phenolic resins, alkyd resins, and petroleum resins as binder resins.

Furthermore, the present invention relates to the waterless lithographic printing ink composition, wherein the rosin-modified phenolic resin has a resin viscosity of 18 to 50 Pa · s (@ 25 ° C.). Here, the resin viscosity is defined as a viscosity at 25 ° C. by a varnish cone plate viscometer obtained by heating and dissolving a mixture of resin / linseed oil = 1/2 by weight at 180 to 200 ° C.

In addition, the present invention relates to the waterless lithographic printing ink composition described above, which does not contain mineral oils as a solvent component.

In addition, the present invention relates to a printed matter using the waterless lithographic printing ink composition.

According to the method of the present invention, an ink composition for waterless lithographic printing having excellent paper resistance, fleshing property, and excellent stain resistance is obtained. Can be obtained. In addition, it is possible to obtain printing ink and printed matter excellent in environmental safety that can suppress or eliminate volatile components from the printing ink.

In the present invention, with respect to various waterless lithographic printing aptitudes that have been insufficient only by combining conventional techniques, a balance is achieved by optimizing the properties of the binder resin and the solvent while using perfluoropolyether oil as an essential material. This is done by providing a vehicle and will be described in detail below.

The weight average molecular weight of the perfluoropolyether oil used in the present invention is in the range of 500 to 20,000, preferably in the range of 1,000 to 10,000. When the weight average molecular weight of the perfluoropolyether oil is less than 500, a large amount of low molecular weight perfluoropolyether oil is present, so that the amount of volatile components increases and the stability on the printing press is not good. On the other hand, when the weight average molecular weight exceeds 20,000, the mixing property with the ink is inferior, so that the fluidity of the ink is deteriorated and the stain resistance is also deteriorated.

The perfluoropolyether oil can be added either in an arbitrary step in the ink production process or in a post-addition method after the ink production. The addition amount is in the range of 0.1 to 10% by weight, more preferably 1 to 5% by weight. If the amount is less than 0.1% by weight, sufficient stain resistance cannot be obtained, and if it exceeds 10% by weight, the fluidity and the inking property of the ink become insufficient.

Examples of the binder resin used in the waterless lithographic printing ink in the present invention include one or more resins selected from rosin-modified phenolic resins, alkyd resins, and petroleum resins.

The rosin-modified phenolic resin used in the present invention is not particularly limited, and gum rosin, wood rosin, tall oil rosin and the like can be typically used as the rosin. As the phenol resin, a novolac type, a resol type, or a novolak-resol composite type phenol resin can be used. As the polyol, glycerin, pentaerythritol and the like can be typically used. The production method of the rosin-modified phenol resin is not particularly limited, such as the order of introduction of these resin raw materials, the reaction catalyst, and the properties such as molecular weight and solubility, but the resin viscosity at 25 ° C. is preferably 18 to 50 Pa · s. . Here, the resin viscosity is defined as a viscosity of a varnish obtained by heating and dissolving a mixture of resin / linseed oil = 1/2 at 180 to 200 ° C. while stirring and dissolving at 25 ° C. If the resin viscosity is less than 18 Pa · s, the cohesive force as an ink is insufficient and the stain resistance is inferior, and if it exceeds 50 Pa · s, the fluidity is deteriorated when the ink is used.

The alkyd resin used in the present invention is preferably an oil-modified alkyd resin comprising a polybasic acid, a polyol, and an oil.

The petroleum resin used in the present invention contains indene, methylindene, vinyltoluene, styrene, α-methylstyrene, β-methylstyrene, cyclopentadiene, dicyclopentadiene, methylbutene, isoprene, pentene, cyclopentene, pentadiene, and the like. A petroleum resin having a double bond can be exemplified. Examples of petroleum resins having double bonds include DCPD petroleum resins made from cyclopentadiene and dicyclopentadiene; C5 petroleum resins such as pentene, pentadiene and isoprene; indene, methylindene, vinyltoluene, styrene, α-methyl C9 petroleum resin made from styrene, β-methylstyrene, etc., copolymer petroleum resin consisting of DCPD and C5 raw materials, copolymer petroleum resin consisting of DCPD and C9 raw materials, C5 and C9 Examples thereof include copolymer petroleum resins made of raw materials, copolymer petroleum resins made of the above-mentioned DCPD, C5, and C9 materials, and are produced using a non-catalytic or Friedel-Crafts type catalyst (cationic polymerization). In particular, it is easy to impart polar groups, and it is easy to adjust to a desired softening point. Therefore, a DCPD petroleum resin, a copolymer petroleum resin comprising DCPD and C5 materials, and a copolymer petroleum resin comprising DCPD and C9 materials A copolymer petroleum resin composed of DCPD, C5 and C9 materials is preferred.

Animal and vegetable oils, fatty acid esters, and alkyl ethers can be used as solvents that can be used when blended as an ink composition that does not contain mineral oil as a solvent component.

Examples of animal and vegetable oils include linseed oil, soybean oil, tung oil, tall oil, cottonseed oil, safflower oil, rapeseed oil, dehydrated castor oil, and regenerated vegetable oil.

Examples of fatty acid esters include alkyl esters of saturated and / or unsaturated fatty acids having 8 to 20 carbon atoms. Examples of the alkyl moiety include linear or branched alkyl groups having 1 to 8 carbon atoms.

Examples of the alkyl ether include ethers derived from saturated and / or unsaturated fatty acid alcohols having 6 to 20 carbon atoms.

The printing ink of the present invention can be used as an ink by adding pigments, dyes, extender pigments as coloring materials, anti-friction agents, drying modifiers, viscosity modifiers, and various solvents as necessary. However, it is not limited to these exemplified substances.

The waterless lithographic printing ink of the present invention can be printed on any printing substrate such as paper or plastic film to obtain a printed matter.

Hereinafter, the present invention will be described with reference to specific examples, but the present invention is not limited to the following examples. In the examples, “part” means part by weight, and “%” means% by weight.

(Example of varnish production)
As binder resins, rosin-modified phenol resin A (weight average molecular weight 224000, softening point 178 ° C., resin viscosity 42 Pa · s), rosin-modified phenol resin B (weight average molecular weight 80000, softening point 170 ° C., resin viscosity 15 Pa · s). AF solvent 5 (manufactured by Shin Nippon Petrochemical Co., Ltd., aroma-free ink solvent), soybean oil as solvent. Aluminum chelate (aluminum diisoproxide monoethyl acetate) was used as a crosslinking agent.

The materials were heated and reacted at 190 ° C. for 1 hour in accordance with the formulation (% by weight) shown in Table 1 to obtain gel varnishes 1 to 4.

(Ink production example)
Together with the gel varnishes 1 to 4, phthalocyanine blue (LIONOL BLUE FG7330 manufactured by Toyo Ink Manufacturing Co., Ltd.) and perfluoropolyether oil (Daikin Kogyo Co., Ltd. 20 weight average molecular weight 2,700) was used, and Example inks 1-4 and Comparative example inks 5-8 were obtained according to a conventional method using 3 rolls.

(Evaluation of ink and printability)
About Example inks 1-4 and Comparative example inks 5-8, the printed matter was obtained using the sheet-fed offset printing machine. Printing conditions: 2,000 sheets of coated paper were printed at a printing speed of 8000 sheets / hour, printing plate temperature 28-31 ° C., printing plate HG-2 (manufactured by Toray Industries, Inc.)
Evaluation items: Table 3 shows the results of evaluating the obtained printed matter and ink characteristics in the following points. 1) Gloss (Measure 60-60 ° reflection gloss of the solid part, the higher the value, the better the gloss) 2) Soil (Contrast (K value) between the solid part and 70% halftone dot part, the higher the value, the better the dirt resistance 3) Slope (Use a spread meter to measure the difference between the flow values after 100 seconds and 10 seconds. The higher the value, the better the fluidity)

It can be seen that Example inks 1 and 2 according to the present invention are superior in stain resistance, gloss, and fluidity as compared with Comparative Examples Inks 5-6. Moreover, it turns out that Example ink 3-4 which does not contain mineral oil is excellent in background stain resistance, glossiness, and fluidity | liquidity compared with comparative example ink 7-8.

Claims (5)

A waterless lithographic printing ink composition comprising a perfluoropolyether oil having a weight average molecular weight of 500 to 20,000. The waterless lithographic printing ink composition according to claim 1, wherein the binder resin contains one or more resins selected from rosin-modified phenolic resins, alkyd resins, and petroleum resins. 3. The waterless lithographic printing ink composition according to claim 2, wherein the resin viscosity of the rosin-modified phenolic resin is 18 to 50 Pa · s (25 ° C.). Here, the resin viscosity is defined as a viscosity at 25 ° C. by a varnish cone plate viscometer obtained by heating and dissolving a mixture of resin / linseed oil = 1/2 by weight at 180 to 200 ° C. 4. The waterless lithographic printing ink composition according to claim 1, which does not contain mineral oil as a solvent component. Printed matter using the waterless lithographic printing ink composition according to any one of claims 1 to 4.