JPH0128787B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fast drying electron beam curable offset ink composition. Hitherto, as offset printing inks, high viscosity inks containing a vehicle in which rosin-modified phenolic resin, maleic acid resin, vegetable oil-modified alkyd resin, etc. are dissolved in high-boiling mineral oil have been used.
However, although such offset inks generally have excellent printability such as ink transferability, they dry by a combination of permeation drying, oxidation drying, and evaporation drying, so they have the disadvantage that the drying time is extremely long. For this reason, in sheet-fed printing, inconvenient phenomena such as show-through and blocking occur when printed matter is stacked, or in order to prevent this, spatially uneconomical methods such as slatting have been used. On the other hand, in offset rotary printing, in order to forcibly heat and dry the printed matter,
There is a disadvantage that equipment costs such as a drying oven, cooling rollers for cooling, exhaust gas treatment equipment, etc. are required, and a large amount of heating and cooling costs are required. In order to eliminate these drawbacks of conventional offset printing inks, it has been proposed to use an ink containing an electron beam curable acrylate monomer as a vehicle and dry it by electron beam irradiation to provide suitability for high speed printing. However, it is difficult for an ink containing only an acrylate monomer as a vehicle to have printability such as ink transferability, and adding additives to improve this has the drawback of decreasing the curing speed. An object of the present invention is to provide an electron beam-curable offset printing ink that has both high-speed drying properties and printability. According to the research conducted by the present inventors, it has been found that the combination of a rosin ester resin having a specific acid value and an acrylate monomer as the main portion of the vehicle is extremely effective in achieving the above-mentioned objective. That is, rosin ester resins with an oxidation of 20 to 100 have good compatibility with acrylate monomers and good stability against dampening water, and acrylate monomers are also easily resistant to electron beam irradiation even in the presence of rosin ester resins. Has quick curing speed. Therefore, by using a rosin ester resin in combination with an acrylate monomer, it is possible to effectively improve printability including ink transferability. Further, since rosin ester resin has excellent curing suitability through oxidative polymerization, an ink made of a combination of acrylate monomer and rosin ester resin has good overall curing suitability through electron beam curing and oxidative polymerization. The electron beam curable offset ink composition of the present invention is based on the above-mentioned knowledge, and has an acid value of 20 to 20.
100 rosin ester resin and an acrylate monomer as main components, and the acrylate monomer is used in an amount of 20 to 500 parts by weight based on 100 parts by weight of the rosin ester resin. The present invention will be explained in more detail below. In the following description, "%" and "part" are based on weight unless otherwise specified. The rosin ester resin used in the present invention is a rosin ester consisting of a condensate of rosin and a polyhydric alcohol such as glycerin, pentaerythritol, or trimethylolpropane; It includes modified rosin esters consisting of condensates with alcohol; and rosin esters consisting of condensates of polymerized rosin and polyhydric alcohols. Preferred specific examples of the rosin ester resin include glycerin ester of rosin, pentaerythritol ester of rosin, pentaerythritol ester of hydrogenated rosin, glycerin ester of hydrogenated rosin, triethylene glycol ester of hydrogenated rosin, and glycerin ester of polymerized rosin. Examples include pentaerythritol ester of polymerized rosin, glycerin ester of maleic acid-modified rosin, and pentaerythritol ester of maleic acid-modified rosin. Two or more of these rosin ester resins can also be used in combination. Among the above-mentioned rosin ester resins, the present invention uses
Those having an acid value in the range of 20 to 100 are used. If the acid value is less than 20, the compatibility with the acrylate monomer described later will be poor, while if the acid value exceeds 100, it will emulsify with dampening water during offset printing, causing scumming. These rosin ester resins have a poor property of copolymerizing with acrylate monomers during electron beam irradiation, but they are excellent in the effect of improving printability, and together with the cured acrylate monomers after electron beam irradiation, they provide a non-sticky film, and they themselves is then oxidatively polymerized and participates in the formation of a strong film. Examples of the acrylate monomer that is the other main vehicle component in the ink composition of the present invention include ethylene glycol diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, diethylene glycol diacrylate, Triethylene glycol diacrylate, dipropylene glycol diacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, diethylaminoethyl acrylate, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-
Ethylhexyl acrylate, isodecyl acrylate, lauryl acrylate, stearyl acrylate, 2-hydroxyethyl acrylate,
2-hydroxylpropyl acrylate, trimethylolpropane triacrylate, methoxyethyl acrylate, n-butoxyethyl acrylate, tetrahydrofurfuryl acrylate, glycidyl acrylate, ethyl carbitol acrylate, methyl triglycol acrylate,
Various acrylic esters such as benzyl acrylate, 1,5-pentanediol diacrylate, pentaerythritol triacrylate, 2-hydroxyethyl acryloyl phosphate, and their corresponding methacrylic esters can be used. These acrylate monomers are used singly or in combination at a ratio of 20 to 500 parts, preferably 25 to 100 parts, based on 100 parts of the rosin ester resin. If it is less than 20 parts, curability by electron beam irradiation will be insufficient, and if it is more than 500 parts, the viscosity and
Printing ink properties such as tack deteriorate, causing background smearing. The offset printing ink of the present invention is mainly composed of the above-mentioned rosin ester resin and acrylate monomer, but in addition to these, it can contain up to 500 parts of recognized ingredients per 100 parts of acrylate monomer. . Such optional components include, for example, drying oils such as linseed oil, castor oil, and tung oil; resins such as alkyd resins, phenolic resins, polyamide resins, natural rubber derivatives, cellulose derivatives, vinyl resins, polyolefins, and petroleum resins; Coloring materials made of dyes or pigments; surfactants, plasticizers, inorganic fillers, etc. However, the ink of the present invention does not substantially contain a solvent component that does not have curing and drying properties,
Substantially all components participate in ink film formation. The offset ink of the present invention is prepared by kneading the above-mentioned components according to a conventional method using a kneading machine such as a three-roll mill, an attritor, a ball mill, or a sand grinder to have a viscosity of usually about 300 to 1000 poise. Ru. The offset ink of the present invention is printed on various types of paper, plastic film, and other base materials according to conventional methods, and then irradiated with electron beams to polymerize and harden the acrylate monomer, thereby preventing at least show-through or blocking of the printed layer. harden to a certain degree. The electron beams used are emitted from various electron beam accelerators such as Kotscroft-Walton type, Van de Graaff type, resonant transformer type, insulated core transformer type, linear type, dynamitron type, and high frequency type.
An electron beam with an energy in the range of 1000 KeV, preferably 100-300 KeV is used. Continuous curing of the printed layer is possible by irradiating a continuous curtain-shaped electron beam, usually from a linear filament, while the printed paper is running continuously. As mentioned above, the electron beam curable offset ink of the present invention combines high-speed drying properties and printability by using an acrylate monomer and a rosin ester resin, but in addition to that, it is electron beam curable. Therefore, coloration caused by sensitizers, which is common in conventional UV-curable inks, does not occur.
Because it utilizes the strong penetrating power of electron beams, it has the advantage of not being affected by the curing inhibiting effects of pigments, plasticizers, and other additives. Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 Glycerin ester of maleic acid-modified rosin with acid value 37 (Louizol 28, manufactured by Hercules, USA)
40 parts and 20 parts of an alkyd resin (phthalic acid/glycerin) with an oil length of 78 modified with linseed oil were heated and melted at 200°C, then cooled to 170°C, and 40 parts of trimethylolpropane triacrylate was added with stirring. I got a varnish. Next, 20 parts of carbon black was added to 80 parts of this varnish and kneaded with a three-roll mill to obtain an ink with a viscosity of 600 poise and a tack of 7.5. Offset rotary printing machine (manufactured by Mitsubishi Heavy Industries, Ltd.)
Rithopia BT-2B) and a low-energy electron accelerator (Electro Curtain CB manufactured by Energy Science)
20d 50/30) using the above ink on coated paper at a speed of 300 m/min, and then irradiated with an electron beam at 1 Mred of radiation, resulting in no blocking and excellent photo-selectivity. I got the print. Furthermore, the stability on the ink roll during printing was excellent, and there were no defects such as piling. Example 2 30 parts of pentaerythritol ester of dibasic acid-modified rosin having an acid value of 36 (Ceroline 102, manufactured by Hercules Co., USA) was heated to 150°C while stirring, and 70 parts of trimethylolpropane triacrylate was added and dissolved to form a varnish. Obtained. Next, 10 parts of dipentaerythritol hexaacrylate and 20 parts of carbon black were added to 70 parts of this varnish, and the mixture was kneaded using three rolls to obtain an ink with a viscosity of 500 poise and a tack of 7.0. Using this ink, printing was carried out in the same manner as in Example 1 to obtain printed matter with excellent dryness and light selectivity. Comparative Example In Example 2, when the resin shown in the table below was used in place of the pentaerythritol ester of the dibasic acid-modified rosin, the properties of the resulting composition were as shown in the right column of the same table. 【table】

Claims (1)

[Claims] 1. An electron beam curable off-site containing a rosin ester resin with an acid value of 20 to 100 and an acrylate monomer, wherein the acrylate monomer is used in an amount of 20 to 500 parts by weight per 100 parts by weight of the rosin ester resin. Set ink composition.