JP2013144765A - Offset printing ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithographic printing ink composition used in lithographic printing, particularly a waterless lithographic printing ink composition not discharging a dampening water, and further a Japanese ink satisfying both scumming tolerance and receptivity, which are problems of waterless printing.SOLUTION: A lithographic printing ink composition contains a pigment, a binder resin, gilsonite, a petroleum solvent, and a plant oil, wherein a rosin-modified phenol resin has a specific weight-average molecular weight and a specific normal paraffin clouding temperature; and the gilsonite has a specific weight-average molecular weight and a specific softening point.

Description

  The present invention relates to a lithographic printing ink composition (hereinafter abbreviated as “ink”) used for lithographic printing for printing books, leaflets, catalogs, posters, etc., and in particular, does not discharge dampening water. The present invention relates to a waterless printing ink that is advantageous for reducing the environmental load, and further relates to a black ink that can achieve both the soil resistance and the inking property, which are problems of waterless printing.

  The waterless printing method in offset printing does not require fountain solution and does not require waste liquid treatment, and is therefore a printing method with less environmental impact. In waterless printing, a silicone rubber layer is used as a dampening water for watery printing, and an image can be formed by repelling ink. Since dampening water is not used as printability, temperature control of the printing press is important. If the roller temperature of the printing press is high, scumming may be induced. In order to avoid scumming, it is common to increase the elasticity of the ink, but if the elasticity of the ink is high, the inking property will deteriorate, so there is no water to achieve both scumming resistance and inking property. It is important for ink design.

  For waterless printing background stains, the theory that the solvent in the ink elutes on the surface of the silicone rubber layer and the solvent forms a layer to prevent the ink from adhering to the non-image area (WFBL theory) is prominent. It is. In order to facilitate the removal of the solvent from the ink, it is a common technique to promote elution into non-image areas by combining a binder resin such as rosin-modified phenolic resin with a solvent that has low compatibility. is there. In the case of a combination with low compatibility, the solvent and the binder resin are difficult to get wet, and the ink is low in fluidity and high in elasticity. Therefore, the inking property is generally disadvantageous as compared with the printed matter with water.

  Recently, the recycling rate of used paper in printing paper has increased, and paper dust generated from the paper during printing tends to adhere to the blanket of the printing press, impairing the inking property, lowering the printing quality, and increasing the number of waste paper and blanket washing. This is a disadvantageous printing cost. In particular, black ink is the first color printed in the four process colors, and is most significantly affected by paper dust.

  Patent Document 1 uses an aliphatic hydrocarbon resin having a softening point of 120 ° C. to 125 ° C. extracted from gilsonite as one component of a binder resin, so that it is superior in carbon black, dispersibility, fluidity, and tack stability. It is mentioned that the ink properties can be improved, the ink properties are improved, the printability such as stain resistance and transferability between rollers can be improved, and the print quality such as gloss and halftone dot reproducibility is improved. However, by using gilsonite having a higher softening point, the solubility with the solvent is lowered, and the elution effect of the solvent is enhanced, whereby the soil resistance can be further improved.

Japanese Patent Laid-Open No. 10-279872

  The present invention has been made in order to solve such problems in the prior art, and the problem is that the transferability between rollers is smooth in waterless printing, and the paper is easily deposited. In addition, the present invention provides a black ink that is excellent in printability and excellent in stain resistance.

  As a result of investigations aimed at solving the current problems, the present inventors, in a lithographic printing ink composition containing a pigment, a binder resin, gilsonite, a petroleum solvent, and a vegetable oil, have a weight average molecular weight within a certain range, By using a rosin-modified phenolic resin having solubility and gilsonite having a certain range of weight average molecular weight and softening point, the inventors have invented a waterless ink that improves the balance between scumming resistance and inking property.

That is, the present invention is a lithographic printing ink composition comprising a pigment, a binder resin, gilsonite, a petroleum solvent and a vegetable oil,
Binder resin
Weight average molecular weight 50000-200000
and
Normal paraffin cloudiness temperature of 110-180 ° C
And
Gilsonite
Weight average molecular weight 2500-4000
and
Softening point 150-180 ° C
The present invention relates to a lithographic printing ink composition.

  Furthermore, the present invention relates to the above-described lithographic printing ink composition, wherein gilsonite is 2 to 15% by weight in the total ink composition.

  Moreover, this invention relates to the printed matter formed by printing said lithographic printing ink composition on a base material.

  Conventionally, in waterless printing, when a binder resin and a solvent having low compatibility are used for the purpose of improving the resistance to soiling due to the solvent elution effect in the WFBL theory, the ink has high elasticity and low fluidity, and the inking property is inferior. Result. According to the present invention, it is possible to provide a waterless ink excellent in fluidity while ensuring a high elution effect, so that the printing cost can be reduced due to good scumming resistance, and at the same time, excellent printing quality due to high flaking property. I can get it.

  The weight average molecular weight of the rosin-modified phenol resin which is a binder resin relating to the present invention is desirably in the range of 50,000 to 200,000, more preferably in the range of 80000 to 170000. If it is less than 50000, stain resistance suitable for waterless ink cannot be imparted, and if the weight average molecular weight exceeds 200000, the step of dissolving the resin to form a varnish becomes difficult.

  The normal paraffin turbidity temperature of the rosin-modified phenolic resin relating to the present invention is preferably in the range of 110 to 180 ° C, more preferably in the range of 130 to 160 ° C. In the present invention, the normal paraffin white turbidity temperature refers to the lower limit temperature at which white turbidity occurs when 10% by weight of resin and 90% by weight of normal paraffin having 14 to 16 carbon atoms are heated and mixed. Is not observed.) If the temperature is less than 110 ° C., the solubility of the resin is too high, and thus the tackiness of the ink is high. If the clouding temperature exceeds 180 ° C., the solubility of the resin is too low, so that the solvent is easily removed and the ink is easily tightened on the machine.

  The weight average molecular weight of Gilsonite according to the present invention is preferably in the range of 2500 to 4000, more preferably in the range of 2800 to 3500. If it is less than 2500, the elasticity of the ink is lowered, which is disadvantageous for background staining, and if it exceeds 4000, the elasticity becomes excessive.

  The softening point of gilsonite relating to the present invention is preferably in the range of 150 to 180 ° C, more preferably in the range of 160 to 175 ° C. If the temperature is lower than 150 ° C., the viscosity of the ink tends to be low, which is disadvantageous for scumming. If the softening point is higher than 180 ° C., the gloss of the printing paper surface may be reduced.

  The addition amount of gilsonite relating to the present invention is desirably 2 to 15% by weight, more preferably 3 to 10% by weight in the total ink composition. If it is less than 2% by weight, there is little elution effect on the non-image area of the plate surface, and it is not possible to ensure the stain resistance. If the weight ratio exceeds 15% by weight, the fluidity becomes excessive, and there is a concern about squeaking. Will increase.

  The printing ink composition of the present invention can be produced by a conventionally known method. As an example, a varnish is produced under a cooking condition of 190 ° C. for 1 hour by adding a rosin-modified phenolic resin, a vegetable oil component, a petroleum solvent, and a gelling agent as required. Also, since Gilsonite is black, it is usually produced separately in a dedicated varnish kettle, and Gilsonite, vegetable oil components, petroleum-based solvents, and other binder resins are added to improve compatibility if necessary. The Gilsonite varnish is produced under cooking conditions of 190 ° C. for 1 hour. Next, for example, a pigment, petroleum-based solvent, vegetable oil, pigment dispersant, etc. are added to the rosin-modified phenolic resin varnish and gilsonite varnish, and dispersed with a bead mill or three rolls to obtain a base for printing ink. I can get it. Subsequently, vegetable oils, paraffinic raw material oils, and other additives are added to adjust to a predetermined viscosity to obtain a printing ink composition. The main types of ink include, but are not limited to, ink for offset rotary printing presses, ink for sheet-fed printing presses, and newspaper inks.

  Examples of the pigment used in the present invention include carbon black. The addition amount of the pigment is 10 to 30% by weight with respect to the total amount of the printing ink composition.

  The binder resin used in the present invention includes rosin-modified phenolic resin, rosin-modified maleic acid resin, alkyd resin, polyester resin, petroleum resin and the like, and these can be used alone or in combination of two or more.

  Gilsonite used in the present invention is mined at Bonanzasite in Salt Lake City, Utah, USA, and oil is impregnated into rocks and transformed into asphalt. A well-refined softening point of about 125 ° C. is used for the purpose of improving the dispersibility and fluidity of black ink.

  The binder resin used in the present invention can be added to a gelling agent such as vegetable oils, petroleum-based solvents and aluminum chelate compounds and dissolved at 190 ° C. or higher and varnished. A gelling agent is not essential. The addition amount of the binder resin is 20 to 40% by weight with respect to the total amount of the printing ink composition.

  The gilsonite used in the present invention can be varnished by adding vegetable oils, petroleum-based solvents, and if necessary, adding other binder resins in order to increase compatibility, and melting at 190 ° C. or higher. . The amount of gilsonite added is 2 to 15% by weight based on the total amount of the printing ink composition.

  The vegetable oils in the present invention are vegetable oils and compounds derived from vegetable oils. Among the triglycerides of glycerin and fatty acids, at least one fatty acid is a fatty acid having at least one carbon-carbon unsaturated bond, and those triglycerides. Examples include fatty acid monoesters obtained by ester reaction with saturated or unsaturated alcohols, or fatty acid monoesters obtained by direct ester reaction between fatty acids of vegetable oil and monoalcohols, and ethers.

  Typical vegetable oils are: Asa seed oil, flaxseed oil, eno oil, psyllium oil, olive oil, cacao oil, kapok oil, kaya oil, mustard oil, kyounin oil, kiri oil, kukui oil, walnut oil, poppy oil, sesame oil , Safflower oil, radish seed oil, soybean oil, daikon oil, camellia oil, corn oil, rapeseed oil, niger oil, nuka oil, palm oil, castor oil, sunflower oil, grape seed oil, gentian oil, pine seed oil Cottonseed oil, palm oil, peanut oil, dehydrated castor oil, and the like.

  The fatty acid monoester is a fatty acid monoester obtained by transesterification of the above vegetable oil and monoalcohol or a direct ester reaction between the fatty acid of the vegetable oil and monoalcohol. Typical monoalcohols are methanol, ethanol, n- or iso-propanol, n, sec or t-butanol, heptynol, 2-ethylhexanol, hexanol, octanol, decanol, dodecanol and other saturated alcohols, oleyl alcohol , Unsaturated fatty alcohols such as dodecenol, huseteri alcohol, somaryl alcohol, gadrelyl alcohol, 11-icosenol, 11-docosenol, 15-tetracosenol.

  Representative examples of ethers include di-n-octyl ether, dinonyl ether, diheptyl ether, dihexyl ether, didecyl ether, nonyl hexyl ether, nonyl heptyl ether, nonyl octyl ether and the like.

  The petroleum-based solvent used in the present invention is a petroleum-based solvent having an aromatic hydrocarbon content of less than 1% by weight, generally called an aroma-free solvent. The initial boiling point of the aroma-free solvent is preferably 240 ° C or higher and 300 ° C or lower. At an initial boiling point of less than 240 ° C, the solvent is likely to evaporate on the rollers of the printing press, resulting in an increase in tack. At an initial boiling point of more than 300 ° C, it becomes difficult to dry in the hot air drying step in offset rotary printing. There is a risk of inducing defects.

  Also, as other additives in the lithographic printing ink composition, various additives for the purpose of anti-friction, anti-blocking, sliding and anti-scrubbing can be used, and if necessary, a surfactant or the like can be used. It may be added.

As an example of the composition of the lithographic printing ink composition of the present invention,
・ Binder resin 20-40% by weight
・ Gilsonite 2-15% by weight
・ Vegetable oils 7-20% by weight
・ Petroleum solvent 20-45% by weight
・ Pigment 10-30% by weight
・ Other additives 1 to 5% by weight
Etc. are mentioned as preferred compositions.

  Examples of the substrate used in the present invention include general printing paper such as coated paper and non-coated paper.

The present invention will be described in more detail with reference to the following examples. However, the following examples do not limit the scope of rights of the present invention. In the present invention, “part” represents “part by weight” and “%” represents “% by weight” unless otherwise specified.
(Rosin modified phenolic resins A to F production example)
In a reaction vessel, 1500 parts of gum rosin was previously reacted in a xylene solvent with 600 parts of tertiary butylphenol and 210 parts of 92% by weight paraformaldehyde at 100 ° C. for 4 hours under a sodium hydroxide catalyst, and 150 wt. The solution was dropped at 0 ° C. and reacted for 2 hours. Further, 160 parts of pentaerythritol was added and reacted at 250 ° C. for 12 hours using 1.5 parts of calcium oxide as a catalyst. By sequentially removing in the course of the reaction, rosin-modified phenol resins A to F were obtained as shown in Table 1.

(Rosin modified phenolic resin varnish A to F production example)
To a stirrer, a reflux condenser with a water separator, and a four-neck flask with a thermometer, 45 parts of the rosin-modified phenolic resin (A to F) as a binder resin, 10 parts of soybean oil, 45 parts of a petroleum solvent,

(AF solvent 7 manufactured by JX Nippon Oil & Energy Corporation was heated and stirred at 190 ° C. for 1 hour to obtain rosin-modified phenolic resin varnishes A to F.

(Gilsonite Varnish A)
In a four-necked flask equipped with a stirrer, a reflux condenser with a water separator, and a thermometer, 30 parts of Gilsonite (Gilsonite Select 325, weight average molecular weight 3100, softening point 163 manufactured by American Gilsonite), 20 parts of soybean oil Then, 50 parts of petroleum solvent and AF solvent 7) manufactured by JX Nippon Oil & Energy Corporation were heated and stirred at 190 ° C. for 1 hour to obtain gilsonite varnish A.

(Gilsonite Varnish B)
Stirrer, reflux condenser with water separator, 4-neck flask with thermometer, 30 parts of Gilsonite (American Gilsonite ER125, weight average molecular weight 2400, softening point 125 ° C.), soybean oil 20 parts, petroleum system 50 parts of solvent (AF solvent 7 manufactured by JX Nippon Oil & Energy Corporation) was heated and stirred at 190 ° C. for 1 hour to obtain Gilsonite varnish B.

(Example of lithographic printing ink composition)
Lithographic printing ink using rosin-modified phenolic resin varnish, gilsonite varnish, carbon black (MA77 manufactured by Mitsubishi Chemical Co., Ltd.) and petroleum solvent (AF Solvent 7) using the three rolls according to the conventional method. Examples of compositions and comparative examples were obtained. The lower part of Table 2 describes the amount of gilsonite in the lithographic printing ink composition.

(Performance evaluation test 1 Ground dirt evaluation test)
The background smudge evaluation test is conducted with the following printing conditions using the NEO800 manufactured by Mitsubishi Heavy Industries, Ltd. as an off-wheel printing machine under the general printing pattern and density, and under the following printing conditions. As shown in Table 3, five grades of relative evaluation were performed. When the evaluation score is 3 or less, there is a high possibility that a problem occurs in actual printing, and when the evaluation score is 4 or more, it can be put to practical use.
CTP version: TAC-VG5 manufactured by Toray Industries, Inc.
Paper: Pearl Coat N manufactured by Mitsubishi Paper Industries Co., Ltd.
Printing speed: 600rpm
Chiller set temperature: 25 ° C

(Performance evaluation test 2 Evaluation of inking properties)
The printed matter obtained in the background stain test was visually evaluated in five stages as shown in Table 4. When the evaluation score is 3 or less, there is a high possibility that a problem occurs in the quality of the printed matter. When the evaluation score is 4 or more, it can be put to practical use.

(Performance evaluation test 3 Evaluation of fluidity)
The lithographic printing ink composition was measured for a radius 1 minute after the start of measurement in an environment of 25 ° C. and 50% RH with a spread meter. When the flow is less than 18.0, the transferability between the rollers is low, and there is a high risk of ink residue and the like.
The performance evaluation test results are shown in Table 5.

  In Examples 1 to 3, both the background stain and the inking property are good, and the fluidity of the ink is also good. In Comparative Examples 1 and 2 in which the weight average molecular weight of the rosin-modified phenolic resin is small and the normal paraffin white turbidity temperature is low, the flow is long and the flesh resistance is good, but the soil resistance is inferior. In Comparative Example 3 having the highest weight average molecular weight, the soil resistance is good, but the flow is short and the inking property is inferior. Comparative Example 4 made only with Gilsonite has a relatively long flow but does not improve the current level in terms of soil resistance and fleshiness. Comparative Example 5 using Gilsonite having a low softening point is inferior in soil resistance. The comparative example 6 which does not contain gilsonite has a short flow and is inferior in wearability.

Claims (3)

A lithographic printing ink composition comprising a pigment, a binder resin, gilsonite, a petroleum solvent and a vegetable oil,
Binder resin
Weight average molecular weight 50000-200000
and
Normal paraffin cloudiness temperature of 110-180 ° C
And
Gilsonite
Weight average molecular weight 2500-4000
and
Softening point 150-180 ° C
A lithographic printing ink composition characterized in that:   2. The lithographic printing ink composition according to claim 1, wherein the gilsonite is 2 to 15% by weight in the total ink composition. A printed matter obtained by printing the lithographic printing ink composition according to claim 1 or 2 on a substrate.