JPS625952B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to printing ink compositions. More specifically, the present invention relates to a new ink composition for dry lithographic printing that does not use dampening water. Because lithographic printing uses dampening water to distinguish between printed and non-printed lines on the plate to create an image, it is difficult to control the quantity and select the quality of dampening water, which is a major hindrance to lithographic printing. . On the other hand, in dry lithographic printing, printing lines and non-printing lines are divided into oleophilic areas and oil-repellent areas, and are divided into inked areas and non-inked areas, so dampening water is not used.
Therefore, there is no need to perform quantitative control or qualitative selection of dampening water, simplifying lithographic printing. However, despite having such great advantages, dry lithographic printing has not yet been fully put into practical use, and this is due to the unsatisfactory printability of dry lithographic inks. It is well known that when conventional oil-based inks are used in dry lithography, they have the disadvantage of causing background smudges due to inadequate printability, which is undesirable. Methods such as increasing the ink tack or adding organopolysiloxane or the like to the ink as an adhesion energy reducing agent have been taken. However, when such a method is used, although background smearing is improved, problems such as insufficient fluidity of the ink and poor on-press stability due to easy phase separation of the composition have emerged, and even now. An ink that satisfies all of stain resistance, fluidity, and on-press stability has not been put into practical use. In view of the above-mentioned circumstances, the present inventors conducted intensive research to develop a dry lithographic printing ink that is excellent in stain resistance, flowability, and on-press stability, and as a result, the present invention was accomplished. That is, the present invention is a novel ink characterized by using a urethane resin varnish having a specific structure as the main component of the vehicle, without using any rosin-modified phenolic resin varnish, which is often used in conventional oil-based inks. The balance of ingredients in the urethane resin varnish gives the ink adhesion to printed areas and the repellency of ink to non-printed areas. The object of the present invention is to provide a dry lithographic printing ink that does not cause generation and has excellent fluidity even at low temperatures. Conventional oil-based inks have rosin-modified phenolic resin as the main component of the vehicle, and when attempts are made to improve background smearing, the ink becomes harder and harder; on the other hand, when attempts are made to soften the ink, background smudge becomes more severe. We are approaching the limits of improvement. When considering a varnish that can replace rosin-modified phenolic resin, a soft, non-scattering ink vehicle for dry lithographic printing must have the following properties: be soluble or dilutable in petroleum fractions, and be suitable for printing areas. Examples include having adhesiveness, having repellency against non-image areas, being soft, having a molecular weight of a certain amount or more, and having an appropriate internal cohesive force. The present inventors focused on urethane resin as a varnish that satisfies the above-mentioned performance requirements, and by using a specific polyol component, it imparts repellency to non-print areas, softness, and solubility to petroleum fractions. The inventors succeeded in imparting adhesiveness and internal cohesive force to the image area by the urethane bonding group produced by the reaction of a polyisocyanate compound and a polyol, leading to the completion of the present invention. That is, the present invention provides an ink for dry lithography using, as an ink vehicle, a urethane resin obtained by reacting a polybutadiene polyol and/or a polyether polyol with an organic polyisocyanate compound. The urethane resin used in the present invention must be soluble in petroleum fractions with a boiling point of 220°C to 350°C, which is generally used as a solvent for lithographic printing inks. A linear or branched urethane resin of any molecular weight can be obtained by reacting a polyether polyol and/or polybutadiene polyol (preferably having a molecular weight of 400 to 6000) with an organic polyisocyanate compound. However, as such urethane resin,
It is preferable that the average molecular weight is 1,000 to 20,000. If it is less than 1,000, it will cause scumming, and if it is more than 20,000, it will tend to cause misting. Preferably, it is a urethane resin having a molecular weight of 3,000 to 8,000, and since it has a relatively low molecular weight, it provides a varnish that is soft and has excellent fluidity. Granted. Since this cohesive force depends on the concentration of urethane bonding groups, the following condition is satisfied: Adhesive force between the non-printing area and the ink < Cohesive force of the ink < Adhesive force between the printing area and the ink. It can be adjusted as appropriate. By kneading this vehicle with a pigment to form an ink, an ink that is soft, has excellent fluidity, and has good stain resistance can be obtained. At that time, depending on the component composition of the urethane resin, the ink adhesion to the printed area may be weak and the printed matter may have a pale tone, in which case polyester polyol with a molecular weight of 200 to 5000 may be used as an alcohol component. Improved by doing. If the molecular weight of the polyester polyol is less than 200, it will not be effective in improving ink receptivity, and if it is more than 5,000, the ink vehicle will lack solubility in petroleum fractions. The amount of polyester polyol to be used, expressed as % by weight based on the total alcohol component, is suitably 5 to 70% by weight relative to 30 to 95% by weight of polybutadiene polyol and/or polyether polyol. The larger the amount of polyester polyol used, the better the ink receptivity, but the cohesive force of the urethane resin varnish increases, causing problems such as lack of ink fluidity and lack of solubility in petroleum fractions. At that time, the boiling point
The above balance can be adjusted by adding one or more liquid mixtures selected from esters, ethers, aldehydes/ketones, and alcohols at 150° C. or higher as a plasticizer or diluent. However, this addition amount is 50% by weight in the ink vehicle.
It is preferable that the amount is less than 50% by weight, and if it is more than 50% by weight, it may cause scumming. Polybutadiene glycol is a typical polybutadiene polyol used in the present invention, but polybutadiene can also be obtained by reacting polybutadiene with peracetic acid, partially containing oxirane oxygen, and reacting this with an amine compound. Also mentioned are polyhydroxybutadiene and the like. In addition, polyether polyols include polyether siols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; alkylene oxides such as ethylene oxide and propylene oxide are added to trihydric alcohols such as glycerin and trimethylolpropane; Examples include the resulting polyether triol. Examples of polyester polyols include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, 1,4-butanediol, hexamethylene glycol, etc.
trihydric alcohols such as glycerin and trimethylolpropane, polyhydric alcohols of tetrahydric or higher hydric content such as pentaerythritol and sorbitol, adipic acid, pimelic acid, glutaric acid, suberic acid, azelaic acid, succinic acid, and malon. acid,
Examples include condensates with organic dicarboxylic acids such as sebacic acid, maleic acid, phthalic acid, and isophthalic acid, and organic tricarboxylic acids such as trimellitic acid. On the other hand, the organic polyisocyanate compounds include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, dianisidine diisocyanate, 1-ethoxy-2,4-diisocyanatebenzene, 1-chloro-2,4-diisocyanatebenzene, Aromatic diisocyanates such as naphthalene diisocyanate, 4,4'-diphenyl diisocyanate, aliphatic diisocyanates such as 1,6-hexamethylene diisocyanate, 1,8-octamethylene diisocyanate, 1,12-dodecamethylene diisocyanate, or xylylene diisocyanate. , organic diisocyanate compounds such as isophorone diisocyanate, organic monoisocyanate compounds such as phenyl isocyanate, trimethylolpropane adducts of the above organic diisocyanates, organic polyisocyanate compounds such as polyisocyanate having a biuret structure, and other known and commonly used organic polyisocyanates. Examples include compounds. The reaction between the alcohol component such as polybutadiene polyol, polyether polyol, polyester polyol, etc. and the organic polyisocyanate compound can be carried out in the absence of a solvent.
It is appropriate to react the OH group in an amount of 1 equivalent or more, preferably 1.1 to 2.0 equivalents, per equivalent of the group. Furthermore, the esters, ethers, aldehydes/ketones, and alcohols with a boiling point of 150°C or higher that are used as necessary in the present invention include:
Acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid,
Cyclohexanecarboxylic acid, benzoic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid,
Acids such as maleic acid, fumaric acid, phthalic acid, trimellitic acid, phosphoric acid, phosphorous acid, methanol,
Ethanol, propanol, butanol, amyl alcohol, hexyl alcohol, octanol, decyl alcohol, lauryl alcohol, stearyl alcohol, oleyl alcohol, cyclohexanol, benzyl alcohol, ethylene glycol, propylene glycol, 1,4-butanediol, hexamethylene glycol, diethylene glycol , esters obtained from alcohols such as glycerin, trimethylolpropane, pentaerythritol, and sorbitol; ethers such as epoxy resins that are dioctyl ether, dilauryl ether, distearyl ether, and diglycidyl ether of bisphenol A;
Examples include aldehydes and ketones such as lauryl aldehyde, myristyl aldehyde, dihexyl ketone, dioctyl ketone, and dilauryl ketone, and alcohols such as octanol, decyl alcohol, lauryl alcohol, myristyl alcohol, oleyl alcohol, and linoleyl alcohol. On the other hand, examples of the petroleum fraction with a boiling point of 220° C. to 350° C. used as an ink solvent in the present invention include generally commercially available ink solvents and kerosene. The ink according to the present invention includes a polyether polyol and/or polybutadiene polyol component that imparts an ink repellency function to non-image areas;
A relatively low molecular weight urethane resin containing a urethane bonding group that provides ink adhesion to the printed area and optionally a polyester polyol component is mixed with a petroleum fraction and optionally an ester. , ethers, aldehydes/ketones,
The ink vehicle consists of a pigment and an ink vehicle dissolved in a polar plasticizer or diluent such as alcohol, and by kneading these components with a roll, as with normal ink, an ink with excellent pigment dispersibility can be easily produced. can do. The ink composition according to the present invention has excellent fluidity (flow value measured by parallel plate viscometer: 28 to 40/1 minute value),
Low tackiness (tack value by incometer: 6~
15), it is very convenient to handle, and there is no occurrence of the urn-up phenomenon or paper peeling phenomenon during long-term printing. Furthermore, even when printed at 40°C, it provides printed matter with good background stain resistance, and has excellent printing properties, such as excellent setting (drying) properties. However, if necessary, conventional oil-based inks (for example, drying oil-modified phthalic acid alkyd resin with an oil length of about 85 to 60%, isophthalic acid alkyd resin,
The ink of the present invention may be blended with an ink consisting of an ink vehicle such as a rosin-modified phenolic resin, a rosin-modified alkylphenol resin, or a vinyltoluene-modified alkyd resin, a pigment, and a petroleum fraction. Next, the present invention will be specifically explained with reference to Examples. Parts and percentages in the examples are by weight. Example 1 <Synthesis of urethane resin varnish> 435 parts of polybutadiene glycol "PB-B-1000" (manufactured by Nippon Soda Co., Ltd.) and 42 parts of tolylene diisocyanate were charged into a four-necked flask, and the mixture was heated at 80°C under a nitrogen blanket. After reacting for 5 hours, complete disappearance of free isocyanate groups was confirmed (in the infrared absorption spectrum).
(identified by absorption at 2240 cm ^-1 ), and a viscous urethane resin was obtained. 318 parts of "Dialen 168" (manufactured by Mitsubishi Kasei Corporation) as a petroleum fraction was added to this resin to obtain a homogeneous transparent solution. (Hereinafter referred to as ink vehicle A) <Ink formulation> Carbon black 20 parts Blue pigment 3 parts Ink vehicle A 77 parts Total 100 parts The ink of the above formulation was mixed several times using a three-roll mill, and the ink tack value was A soft ink with a diameter of 9.5, a diameter of 34.8, and a slope of 8.0 was obtained. Example 2 <Synthesis of urethane resin varnish> In a four-necked flask, 290 parts of polybutadiene glycol "PB-B-1000" and 40 parts of "MDI-CR" (manufactured by Mitsui Nisso Urethane Co., Ltd.) as a polyfunctional organic isocyanate compound were added. 5 minutes at 80℃ under a nitrogen blanket.
After a period of reaction, a viscous urethane resin without free isocyanate groups was obtained. This resin has “dialene”
140 parts of ``168'' were added to obtain a uniform brown solution. (Hereinafter referred to as ink vehicle B) <Ink formulation> Carbon black 20 parts Blue pigment 3 parts Ink vehicle B 65 parts "Dialen 168" 12 parts Total 100 parts The ink with the above formulation was kneaded several times using a three-roll mill. The mixture was mixed to obtain a soft ink with an ink tack value of 12.6 and a diameter value of 32.6. Example 3 <Synthesis of urethane resin varnish> In a four-necked flask, 300 parts of polybutadiene glycol "PB-B-1000" and polyester diol (condensation product of ethylene glycol, hexamethylene glycol, adipic acid and phthalic acid: average molecular weight 800) ) 75 parts and tolylene diisocyanate 40
and reacted at 80℃ for 5 hours under a nitrogen blanket.
A viscous urethane resin without free isocyanate groups was obtained. To this resin, 160 parts of "Dialen 168" and polyester plasticizer "Monocizer W-700"
(manufactured by Dainippon Ink & Chemicals Co., Ltd.) was added to obtain a uniform milky white solution. (Hereinafter referred to as Ink Vehicle C) <Ink Formula> Carbon Black 20 parts Blue pigment 3 parts Ink Vehicle C 65 parts "Dialen 168" 12 parts Total 100 parts The ink with the above formulation was kneaded several times using a three-roll mill. The mixture was mixed to obtain a soft ink with an ink tack value of 10.0, a diameter value of 33.4, and a slope of 7.8. Example 4 <Synthesis of urethane resin varnish> Polypropylene glycol "DIOL-3000" (manufactured by Mitsui Nisso Urethane Co., Ltd.) 340 was placed in a four-necked flask.
1 part, 60 parts of polyester diol (condensation product of ethylene glycol, hexamethylene glycol, adipic acid, and phthalic acid: average molecular weight 800) and 50 parts of isophorone diisocyanate, and after reacting at 80°C for 4 hours under a nitrogen blanket, 2 parts of methanol was added. was added and further reacted at 50°C for 2 hours to obtain a viscous urethane resin free of free isocyanate groups. 140 parts of "Dialen 168" and 50 parts of "Monocizer W-700" were added to this resin to obtain a homogeneous solution. (Hereinafter referred to as ink vehicle D.) <Ink formulation> Carbon black 20 parts Blue pigment 3 parts Ink vehicle D 60 parts ``Dialen 168'' 17 parts Total 100 parts The ink with the above formulation was kneaded several times using a three-roll mill. The mixture was mixed to obtain a soft ink with an ink tack value of 11.8 and a diameter value of 31.2. Example 5 <Synthesis of urethane resin varnish> Into a four-necked flask, 150 parts of trifunctional polypropylene polyol "MN-3050" (manufactured by Mitsui Nisso Urethane Co., Ltd.) and polybutadiene glycol "PB" were added.
-B-1000'' 125 parts, polyester diol (diethylene glycol, 1,4-butanediol,
Condensate of adipic acid and phthalic acid: average molecular weight
2000) 150 parts and 50 parts of 1,4-diphenylmethane diisocyanate and heated at 80℃ under nitrogen blanket.
After reacting for 5 hours and confirming complete disappearance of free isocyanate groups, 155 parts of spindle oil and polyester plasticizer "Polycizer W-1000" were added.
(manufactured by Dainippon Ink and Chemicals Co., Ltd.) was added to obtain a homogeneous solution. (Hereinafter referred to as ink vehicle E.) <Ink formulation> Carbon black 27 parts Blue pigment 4 parts Ink vehicle E 60 parts Spindle oil 9 parts Total 100 parts The ink of the above formulation was mixed several times using a three-roll mill. A soft ink with an ink tack value of 8.9 and a diameter value of 32.7 was obtained. Comparative Example 1 An ink was formulated using a conventional rosin-modified phenolic resin varnish. Carbon black 20 parts Blue pigment 3 parts Rosin-modified phenolic resin varnish 9 parts Rosin-modified phenolic resin gel varnish 52 parts "Dialen 168" 16 parts Total 100 parts An ink with a value of 10.9 and a diameter of 30.6 was obtained. Application example 1 An anchor coat resin layer is formed on polyethylene laminate paper, and a fluorine-containing silicone resin layer is coated on top of the anchor coat resin layer. Epoxy is applied to the dry planographic original plate using a dry electronic copying machine (-Bix1500 manufactured by Konishiroku Photo Industry Co., Ltd.). A toner image was developed and fixed using a toner whose main component was resin, and a lithographic printing plate was prepared. This plate was printed on a small offset printing machine (ABDICK
326 model) manufactured by the company, without using dampening water.
5000 sheets were printed at ℃. We observed the adhesion of various inks to non-print areas (background stains), ink adhesion to printing paper (image density), ink hardness during handling, on-machine stability, and storage stability, and reported the results. It is shown in Table 1. 【table】

Claims (1)

[Scope of Claims] 1. An ink for dry lithographic printing characterized in that a urethane resin obtained by reacting a polybutadiene polyol and/or a polyether polyol with an organic polyisocyanate compound is used as an ink vehicle. 2. The molecular weights of the polybutadiene polyol and polyether polyol are each 400 to 6000,
The ink according to claim 1, wherein the urethane resin has a molecular weight of 1,000 to 20,000. 3. The ink according to claim 1, which uses a polyester polyol together with a polybutadiene polyol and/or a polyether polyol. 4 Molecular weight of polyester polyol from 200 to
5,000, according to claim 3. 5. The ink according to claim 3 or 4, wherein 5 to 70% by weight of polyester polyol is used together with 30 to 95% by weight of polybutadiene polyol and/or polyether polyol.