JPS6221035B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an ink composition for waterless planographic printing, and more particularly to an ink composition that allows practical printing without using dampening water even when using general planographic materials. In lithographic printing, dampening water is used to prevent ink from adhering to non-print areas, but it is very difficult to adjust this dampening water, and if it is not balanced with the ink, it may cause scumming on the plate, for example. Problems such as the ink becoming emulsified and the lines becoming unclear occur. For this reason, various studies have been conducted to remove dampening water from lithographic printing, such as providing a non-adhesive thin film such as silicone rubber on the non-image areas of the lithographic material.
Emulsifying and mixing a polar substance in the ink to be used as a dampening solution; Using an ink with a higher cohesive force than general lithographic ink; Using an ink with a specific incometer value; Organopolysiloxane in the ink. or using a silicone-modified resin as an ink vehicle. However, none of them have problems such as not being able to satisfactorily exhibit practical printability, requiring a combination of special plate materials and special inks, or requiring the use of expensive agents as essential components. However, it has not yet been put into practical use. The present inventors conducted various studies in order to develop a practical technique that can perform waterless lithographic printing using general lithographic materials.
(The sum of the numbers of alcohol oxygen and ether oxygen in the molecule) ratio (hereinafter referred to as carbon oxygen ratio) is less than 2.0 and the molecular weight is 62 to 151. When a soluble resin is mixed with a group hydrocarbon solvent, the ink does not adhere to the non-image areas of the planographic material, and by adding a nonionic surfactant to the above composition, a practical ink can be created. The inventors have discovered that an ink composition having these characteristics can be made, and have completed the present invention. That is, the gist of the present invention is to provide 10 to 35 wt. 50% by weight of an ink vehicle, 0.2 to 5% by weight of a nonionic surfactant, and 5 to 40% by weight of both the solvent and plasticizer, and 30% by weight or less of a coloring agent. The invention consists in an ink composition for waterless lithographic printing having characteristics. The polyhydric alcohol used in the present invention is essentially incompatible with other components in the ink composition, especially the resin, and therefore tends to separate from the system, causing the ink composition to come into contact with the plate surface. At this time, it is thought that the ink preferentially blends into the non-printing areas of the plate, forming an ink-repellent layer. On the other hand, the main ink component consists of a resin insoluble in the polyhydric alcohol and a colorant,
It is thought that it preferentially blends into the printed areas of the plate, and does not blend into non-printed areas due to the action of the polyhydric alcohol attached to these areas. As is clear from the above discussion, the oleophobicity of the polyhydric alcohol used in the present invention is an important factor, and as a result of repeated various studies, it is only possible when the carbon-oxygen ratio in the polyhydric alcohol is less than 2.0. It has been found that waterless lithographic printing can be performed without causing background smearing. In addition, oxygen in this case does not have sufficient oleophobicity when included in groups such as ketones and esters,
It was found to be effective only when included in alcohol or ether groups. In addition, this polyhydric alcohol has a large effect on the viscosity of the ink composition, and if a polyhydric alcohol with a molecular weight of 152 or more is used, the viscosity becomes high and it is impossible to obtain an ink composition that has practical printability. As polyhydric alcohols, only polyhydric alcohols having a molecular weight ranging from ethylene glycol having the lowest molecular weight to 151 are practically used. Furthermore, if monohydric alcohol is used instead of polyhydric alcohol, it will appear as background stains during printing.
It turned out that it cannot be used in the present invention. It must probably have two or more hydrophilic groups, one that fits into the non-printing area of the plate and one that repels ink, and for this purpose it must be an alcohol group. seems to be an essential requirement. Therefore, the polyhydric alcohol that can be used in the present invention has a carbon oxygen ratio of less than 2.0 and a molecular weight of 62 to 62.
It is limited to 151 polyhydric alcohols, including the following specific examples:

[Table] In the present invention, the above polyhydric alcohols may be used alone or in a mixture of two or more, but from the viewpoint of adjusting the ink viscosity and preventing scumming, ethylene glycol, diethylene glycol and It is preferable that any one type of glycerin is included. Further, a component similar to a polyhydric alcohol such as water or glycolic acid may be added to the polyhydric alcohol, but it is not preferable to use a large amount in view of scumming. If the polyhydric alcohol content in the ink is too low, scumming will occur, and if it is excessive, the ink concentration cannot be increased, the ink will not come out from the ink well, and the transferability of the ink will be poor. Therefore, the content of polyhydric alcohol is preferably 10 to 35% by weight. Ink compositions containing polyhydric alcohols are already known as moisture setting inks or steam setting inks, but in the case of these inks, the resin is soluble in the polyhydric alcohol and there is no need for water. Even when used in lithographic printing, it causes background smearing, making it impossible to print effectively. Further, the polyhydric alcohol also dissolves water-insoluble resins, and only needs to have the property of being soluble in water, and has different characteristics from the polyhydric alcohol used in the present invention. The resin used in the present invention must have the property of not causing background smearing and adapting to the image area, and as a result, it must be insoluble in the above polyhydric alcohol and soluble in aliphatic hydrocarbon solvents. Only the following resins are used. When a resin that dissolves in polyhydric alcohol is used, scumming occurs, and when a resin is insoluble in an aliphatic hydrocarbon solvent, it is difficult to select a solvent and a plasticizer, and appropriate ink characteristics cannot be imparted. Examples of this type of resin include those used in general lithographic inks, such as phenolic resin, rosin-modified phenolic resin,
There are rosin esters, maleic acid resins, alkyd resins, acrylic resins, petroleum resins, polyamino resins, aminoalkyd resins, etc., but rosin-modified phenolic resins are particularly preferably used from the viewpoint of ink properties. The content of the above resin in the ink is 20 to 50% by weight.
is preferable, and if the amount is less than this, the ink will not come out from the ink fountain easily, and a so-called fountain escape phenomenon will occur. On the other hand, if it is in excess, the amounts of colorants such as pigments and solvents will be limited, making it impossible to obtain practical ink density and viscosity. The ink composition according to the present invention can essentially perform waterless lithographic printing by suitable selection of polyhydric alcohol and resin, but also has good printability when a nonionic surfactant is used in combination. It can be ink. This nonionic surfactant mainly provides appropriate compatibility between the resin and polyhydric alcohol, lowers the viscosity of the ink, and provides appropriate transfer properties.It also improves the compatibility between the coating material and the resin, reducing the viscosity of the ink. Effective for lowering and increasing concentration. On the other hand, cationic surfactants and anionic surfactants make the resin and polyhydric alcohol blend too well, causing scumming. Usable nonionic surfactants include common ones, such as polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, polyoxyethylene alkyl phenyl ether, polyhydric alcohol fatty acid ester,
Specific examples include polyoxyethylene polyhydric alcohol fatty acid esters and sucrose fatty acid esters, with polyoxyethylene alkyl ethers and polyoxyethylene fatty acid esters (eg, polyoxyethylene monolaurate) being preferred. Such nonionic surfactants are usually added in an amount of 0.2 to 5% by weight; if the amount is less than this, the above-mentioned characteristics will not be exhibited, and if it is in excess, no improvement in effectiveness will be seen, and conversely, scumming will occur. let The solvent used in the present invention may be one known as a solvent for general lithographic inks, and an aliphatic hydrocarbon solvent having a boiling point of 180 to 320°C, such as light oil, is used.
If the solvent has a boiling point below 180°C, the solvent will evaporate on the printing press roller, increasing the viscosity of the ink. On the other hand, a solvent with a boiling point above 320°C will slow down the setting of the ink. The plasticizer used in the present invention is used to reduce the viscosity of the ink and improve workability during printing, and since it functions in a similar manner to the above-mentioned solvent, it can be used interchangeably with the solvent. and plasticizer in an amount of 5 to 40% by weight in the ink. Although it varies depending on the type of resin used, it is more preferable that the total amount of both is 20 to 35% by weight; if it is less than this, the viscosity of the ink will become high, and if it is in excess, scumming is likely to occur. Usable plasticizers include ordinary ones;
Phthalate esters (e.g. dioctyl tetrahydrophthalate, dioctyl phthalate, dibutyl phthalate), dibasic acid esters (e.g. di-(2-ethelhexyl) adipate, diethyl succinate),
Fatty acid esters (e.g. butyl stearate, butyl oleate), phosphoric acid esters (e.g. tri-(2-ethylhexyl) phosphate, triphenyl phosphate), other esters (e.g. diethylene glycol dibenzoate, methyl phthalylethyl glycolate), etc. is exemplified. The coloring material used in the present invention may be a pigment or dye used in general lithographic inks, and the amount thereof may be appropriately selected according to a conventional method depending on the ink concentration, and is usually used at 30% by weight or less. It will be done. In the ink of the present invention, conventional dispersants, wetting agents, leveling agents, silicone additives, etc. may be appropriately blended in order to adjust various properties of the ink as long as they do not cause scumming. In addition, known ink additives such as compounds and varnishes can also be used. The ink composition of the present invention may be prepared using the above-mentioned components in the same manner as general lithographic inks, for example, by dispersing the colorant in a roll mill or the like. According to the ink composition of the present invention, it is possible to perform printing using ordinary planographic materials without using dampening water, and it is possible to carry out simple and convenient printing, and it is possible to perform printing not only in offset printing but also in offset printing. It is also possible to use it for direct lithographic printing. As the planographic material, commonly used ones such as offset PS plates, wipe-on plates, direct plates, etc. can be used. In addition, operations such as rubberization, which are performed in normal lithographic printing, are not necessary.
If the hydrophilicity of the non-image areas is not sufficient depending on the type of plate, prevent scumming by pre-wetting the plate with water, the above-mentioned polyhydric alcohol, or a hydrophilic substance containing them before printing. I can do it. Next, the present invention will be specifically explained with reference to Examples. In the examples, "parts" means "parts by weight." Example 1 30 parts of a commercially available rosin-modified phenolic resin (Arakawa Hayashi's "Tamanol 135"), 11 parts of light oil and 16 parts of dioctyl tetrahydrophthalate were mixed and heated at 140°C.
Dissolve by heating. 57 parts of the resulting resin solution was added to ethylene glycol.
13 parts of glycerin, 2 parts of nonionic surfactant (Kao Atlas "Emanone 1112"), 13 parts of carbon black (Cabot "Mogul L") and 2 parts of Prussian blue (Dainichiseika "Konsei NBB-2A"). Then, disperse using a three-roll mill. The obtained ink and the commercially available offset plate made
As a result of a printing test using a PS plate (Fuji Photo Film "SSN") and an offset printing machine (Hamaduster "Hamaduster 700CD") with the dampening liquid supply device removed, there was no background smearing without using dampening water. Good printing was achieved. Example 2 Using the same ink as in Example 1, using Mitsubishi Paper Industries'"SilvamasterR" as a plate and AB Dick's "350CD" as a printing machine, the plate-made plate was wetted with a mixture of equal amounts of ethylene glycol and glycerin. death,
As in Example 1, a printing test was conducted with the dampening liquid supply device removed, and as a result, good printed matter was obtained without using dampening liquid. Example 3 Resin: Rosin-modified phenolic resin (same as Example 1) 12.5 parts Rosin-modified phenolic resin (Arakawa Forestry "Tamanol 340") 12.5 parts Alkyd resin (Dainippon Ink "Betsukosol P-470") 4.5 parts Solvent: Light oil 14 parts Plasticizer: Dioctyl tetrahydrophthalate 15.5 parts Surfactant: Nonionic surfactant (same as Example 1) 2 parts Polyhydric alcohol: Ethylene glycol 10.5 parts Glycerin 10 parts Colorant: Carbon black (same as Example 1) )
18.5 parts An ink was prepared from the above formulation in the same manner as in Example 1, and printing was performed using this in the same manner as in Example 1, and the same results as in Example 1 were obtained. Example 4 Resin: Rosin-modified phenolic resin (same as Example 1) 24 parts petroleum resin (Arakawa Forestry “Marukon P125”)
8 parts Solvent: Light oil 14 parts Plasticizer: Dioctyl tetrahydrophthalate 12 parts Surfactant: Nonionic surfactant (Kao Atlas "Tween 85") 2 parts Polyhydric alcohol: Ethylene glycol 9 parts Diethylene glycol 10 parts Glycerin 9 parts Colorant : Carbon black (same as Example 1)
12 parts An ink was prepared from the above formulation in the same manner as in Example 1, and when printing was performed using this in the same manner as in Example 1, the same results as in Example 1 were obtained. Example 5 Resin: Rosin-modified phenolic resin (same as Example 1) 30 parts Solvent: Light oil 13 parts Plasticizer: Dioctyl tetrahydrophthalate 13 parts Surfactant: Nonionic surfactant (Kusumoto Kasei "Disparon #3600-N") ) 1 part polyhydric alcohol: 13 parts ethylene glycol 8 parts glycerin 4 parts pentaerythritol Coloring agent: 18 parts dark blue pigment (same as Example 1) An ink was prepared from the above formulation in the same manner as in Example 1, and this When printing was carried out in the same manner as in Example 1, the same results as in Example 1 were obtained. Example 6 Resin: Rosin-modified phenolic resin (same as Example 1) 30 parts Solvent: Light oil 12 parts Plasticizer: Dioctyl phthalate 14 parts Surfactant: Nonionic surfactant (same as Example 1) 2 parts Polyhydric Alcohol: Diethylene glycol 20 parts Glycerin 6 parts Coloring agent: Red pigment (Fuji Color "Fujired 4R")
16 parts When an ink was prepared from the above formulation in the same manner as in Example 1, and printing was performed using this in the same manner as in Example 1, the same results as in Example 1 were obtained. Example 7 Resin: Rosin-modified phenolic resin (same as Example 1) 30 parts Solvent: Light oil 14 parts Plasticizer: Di-(2-ethylhexyl adipate)
12 parts Surfactant: Nonionic surfactant (same as Example 4) 2 parts Polyhydric alcohol: Ethylene glycol 7 parts Diethylene glycol 10 parts Glycerin 8 parts Colorant: Yellow pigment (Kikuchi pigment "LF Yellow Color")
18 parts 5GSZ'') 18 parts An ink was prepared from the above formulation in the same manner as in Example 1, and when printing was carried out in the same manner as in Example 1, the same results as in Example 1 were obtained. .

Claims (1)

[Claims] 1 The ratio of (number of carbon atoms in the molecule)/(sum of the number of alcohol oxygens and ether oxygens in the molecule) is 2.0
Polyhydric alcohol with a molecular weight of 62 to 151 less than 10 to
35% by weight, 16 to 50% by weight of a resin insoluble in the polyhydric alcohol and soluble in aliphatic hydrocarbon solvents, 0.2 to 5% by weight of a nonionic surfactant, and 5 to 40% by weight of both the above solvent and plasticizer. An ink composition for waterless lithographic printing, characterized in that it is a mixture of 70% by weight or more of an ink vehicle containing: and 30% by weight or less of a colorant.