JP2010260896A - Planographic printing ink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide unprecedented environment-responsive ink without using petroleum solvents at all, without degrading adequacy to rubber materials on a printer, giving performances excellent in drying characteristics and stability on machines, and utilizing an environment-responsive resin for a varnish resin. <P>SOLUTION: The planographic ink includes a resin (a) for varnish containing a rosin ester resin as a main ingredient, and a solvent except for petroleum solvents, wherein the solvent comprises a compound (b) of general formula (1) and a compound (c) of general formula (2) in a ratio of (c):(b)=(0 to less than 30):(100-70) (mass%). In general formula (1), R1 is 4-22C alkyl or alkenyl, R2 is 1-22C alkyl. In general formula (2), R3 is 3-11C alkyl or alkenyl, R4 is 5-14C alkyl. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a lithographic printing ink (hereinafter sometimes simply referred to as “ink”), and more specifically, does not use any petroleum-based solvent obtained from a conventional petroleum fraction, but uses a solvent derived from a specific vegetable oil. Moreover, by using a resin for varnishes that minimizes the use of petroleum-based raw materials, the rubber on the printing press has a better balance between evaporative drying and machine stability than conventional inks using petroleum-based solvents. The present invention relates to an environmentally friendly ink that does not impair the suitability of the material.

  Conventionally, an ink used for lithographic printing, especially an ink used for offset rotary printing, uses a petroleum solvent that can be evaporated under moderate heating conditions. As the solvent for the varnish resin, it is necessary to adjust the drying property and the on-machine stability on the printing press. Therefore, select solvents having different boiling points, or mix and combine them appropriately. The prescription to be used must be taken.

  The above formulations often result in conflicting ink drying and on-machine stability. If a high-boiling petroleum solvent is used in order to improve the on-machine stability, the ink evaporative drying property is lowered, and the ink film is poorly dried and hardened. This is due to the wide boiling range of petroleum solvents, and the high boiling point solvent that cannot be evaporated under the heating conditions of the actual dryer remains in the ink.

  In addition, the use of the above-mentioned petroleum-based solvents is not preferable from the viewpoint of environmental measures such as protection against depletion of petroleum resources and reduction of environmental load. Therefore, environmentally friendly inks in which petroleum-based solvents are replaced with vegetable oil-derived solvents are used. It is being considered.

  A certain kind of printing ink (Patent Document 1) is disclosed as the above-mentioned environment-friendly ink. The ink composition disclosed in Patent Document 1 is composed mainly of a rosin-modified phenolic resin and a vegetable oil fatty acid ester as a solvent, but the presented fatty acid ester has a boiling point much higher than that of conventional petroleum solvents. Very expensive. For this reason, inks using these solvents cannot be used for web offset printing that requires heat set drying performance. Further, since rosin-modified phenolic resin is a main component as a resin for varnish, the resin contains a large amount of petroleum-based raw materials such as alkylphenol, which is insufficient for environment.

  In view of the above, there has been a demand for an ink that is excellent in drying property and on-machine stability and has a small amount of petroleum-based raw material in the ink.

JP 2002-69354 A

  Therefore, the object of the present invention is to use a petroleum solvent, do not impair suitability for a rubber material on a printing press, obtain a performance excellent in drying property and on-press stability, and in a varnish resin. In addition, by using a resin that is environmentally friendly, it is possible to provide an unprecedented environmentally friendly ink.

  As a result of intensive studies to solve the above problems, the inventors of the present invention contain a varnish resin (a) mainly composed of a rosin ester resin and a solvent, and the solvent is identified as a specific compound (b). Ink containing a specific amount of the compound (c) and containing no petroleum solvent is excellent in drying properties and on-machine stability, and is suitable for rubber materials such as ink rollers and blankets of printing presses. It has been found that it is effective in obtaining a lithographic printing ink that is environmentally friendly.

  In other words, by replacing the conventionally used petroleum-based solvent with a specific compound (b) derived from a vegetable oil having a narrow boiling range and high solubility in resin components for varnishes, printing without greatly impairing the drying properties of the ink By using the varnish resin (a) with little increase in the tackiness of the ink on the press and excellent stability on the printing press and further with a low content of petroleum-based raw materials, an ink with a low environmental load can be obtained. Moreover, drying property and on-machine stability can be manipulated by blending the compound (d) with the compound (c) or the compound (c). The compound (c) has better suitability for the rubber material of the ink roller and blanket of the printing press than the compound (d).

The above object is achieved by the present invention described below. That is, this invention contains the resin (a) for varnish which has rosin ester resin as a main component, and a solvent, and this solvent is represented by the following general formula (b) and the compound (b) represented by the following general formula (1). 2) The compound (c) represented by 2) is contained in a ratio of (c) :( b) = 0 to less than 30% by mass: 100 to 70% by mass, and contains no petroleum solvent. Provide ink.
R1-O-R2 (1)
(R1 in the above formula represents an alkyl group or alkenyl group having 4 to 22 carbon atoms, and R2 represents an alkyl group having 1 to 22 carbon atoms.)
R3COOR4 (2)
(R3 in the above formula represents an alkyl group or alkenyl group having 3 to 11 carbon atoms, and R4 represents an alkyl group having 5 to 14 carbon atoms.)

Moreover, in preferable embodiment of this invention, the said compound (c) contains the compound (d) represented by following General formula (3).
R5COOR6 (3)
(R5 in the above formula represents an alkyl group or alkenyl group having 10 to 18 carbon atoms, and R6 represents an alkyl group having 1 to 4 carbon atoms.)
The compounding ratio of the compound (c) and the compound (d) is (d) :( c) = 1-10% by mass: 99-90% by mass, and the cloud point of the rosin ester resin is 50 ° C. It is preferable that the temperature is ˜200 ° C., the weight average molecular weight is 20,000 to 500,000, a colorant is further contained, and the above-mentioned ink is an offset rotary printing ink.

  According to the present invention, the ink according to the present invention is an environment-friendly ink having an excellent balance between drying property and on-machine stability and suitability for rubber materials on a printing machine without using any petroleum solvent. In particular, it is effective for obtaining a high-speed offset rotary printing ink.

  Next, the present invention will be described in more detail with reference to the best mode for carrying out the invention. The ink of the present invention contains a varnish resin (a) mainly composed of a rosin ester resin and a solvent, and the solvent comprises a specific compound (b) and a specific compound (c) (c) :( b) = 0 to less than 30% by mass: 100 to 70% by mass, preferably (c) :( b) = 0 to 29% by mass: 100 to 71% by mass, and no petroleum solvent Is. When the ratio of the compound (b) to the compound (c) is within the above range, the balance between the drying property and on-machine stability of the obtained ink and the suitability for rubber materials such as ink rollers and blankets on the printing machine. Exerts an extremely excellent effect.

  As the rosin ester resin constituting the resin for varnish (a), for example, an unsaturated polybasic acid and / or an unsaturated monocarboxylic acid are added to a rosin or a mixture of a rosin and another diene compound. Examples thereof include a rosin ester resin obtained by reacting the addition reaction product and esterified with a polyol. The rosins, diene compounds, unsaturated polybasic acids and / or unsaturated monocarboxylic acids, and polyols used in the synthesis of the rosin ester resin are conventionally known and have no problem.

  Examples of rosins used for the synthesis of the above rosin ester resins include natural rosins such as wood rosin, gum rosin, tall oil rosin, dimerized rosin obtained by heat polymerization of rosin under catalyst, or polymerized rosin, hydrogenated Rosin and the like, and mixtures thereof.

  Examples of the diene compound used by mixing with the above rosins include diolefin compounds such as 1,3-pentadiene petroleum resin and 1,4-pentadiene petroleum resin, cyclopentadiene petroleum resin, and mixtures thereof. Can be mentioned.

  Further, as unsaturated polybasic acid and / or unsaturated monocarboxylic acid, suitable for diene compound and Diels-Alder reaction (diene synthesis), for example, acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, angelic acid, tigulin Examples include acid, α-ethylcrotonic acid, maleic acid, fumaric acid, citraconic acid, mesaconic acid, itaconic acid, maleic anhydride, itaconic anhydride and the like.

  In addition, as the polyol, low molecular polyols such as ethylene glycol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, trimethylolpropane, pentaerythritol, polyethylene glycol, polypropylene glycol, glycerin, etc. Polyol compounds such as polyols, other polyester polyols and polyether polyols can be mentioned.

  The rosin ester resin preferably has a cloud point of 50 ° C to 200 ° C, more preferably 50 ° C to 150 ° C, and a weight average molecular weight of 20,000 to 500,000, more preferably 50,000 to 200. , 000. When the cloud point and the weight average molecular weight are within the above ranges, the fluidity and viscoelasticity of the ink obtained are more excellent. In addition, the weight average molecular weight in this invention is the value converted into standard polystyrene measured by GPC.

  In addition, the cloud point in the present invention is a ratio of x / y = 1/9 (mass ratio) between the measurement sample (x) and the petroleum solvent Solvent (y) manufactured by Nippon Oil Co., Ltd. It is a cloud point value measured by a temperature lowering operation after being melted by heating until the resin is dissolved.

  The varnish resin (a) may contain the rosin ester resin alone or other rosin-modified phenolic resin, alkyd resin, gilsonite resin, petroleum resin, etc. as long as the object of the present invention is not impaired. You can also. The compounding quantity is less than 50 mass% in resin (a) total amount for varnish.

  Examples of the rosin-modified phenol resin include a resole resin, a rosin and / or a condensation product of rosin and an unsaturated carboxylic acid, and a reaction product of a polyhydric alcohol. The above-mentioned resol resin is p-tertiary butylphenol, p-secondary butylphenol, p-octylphenol, nonylphenol, alkylphenols such as butylphenol and amylphenol, bisphenol A, cresol, etc., preferably the alkyl group has 4 to 12 carbon atoms. It is a condensation product of phenols such as alkylphenol and formaldehyde.

  Examples of the rosin to be reacted with the resole resin include various rosins such as gum rosin, wood rosin, tall oil rosin, polymerized rosin, and disproportionated rosin. Examples of the unsaturated carboxylic acid that forms a condensation product with the rosin include, for example, maleic acid, fumaric acid, itaconic acid, citraconic acid and the like, and anhydrides thereof, dimer acid, trimer acid, and acrylic acid. And methacrylic acid.

  Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, 1,6-hexanediol, glycerin, pentaerythritol, dipentaerythritol, trimethylolpropane, diethylene Examples include divalent or higher alcohols such as glycerin.

The compound (b) is an ether represented by the following general formula (1).
R1-O-R2 (1)
(R1 in the above formula represents an alkyl group or alkenyl group having 4 to 22 carbon atoms, and R2 represents an alkyl group having 1 to 22 carbon atoms.)
Said compound (b) can be used individually or in mixture of 2 or more types. Said compound (b) is effective in improving the balance of the drying property and on-machine stability of the ink obtained. Among the compounds (b), those having R1 and R2 having 4 to 14 carbon atoms are preferable, and those having R1 and R2 having 8 carbon atoms are particularly preferable.

  Examples of the compound (b) include symmetric or asymmetric ether synthesized by a known method such as n-butyl tert-butyl ether, diisoamyl ether, dihexyl ether, diheptyl ether, dioctyl ether, dinonyl ether. , Didecyl ether, diundecyl ether, didodecyl ether, nonyl hexyl ether, nonyl heptyl ether, nonyl octyl ether, etc., preferably dihexyl ether, diheptyl ether, dioctyl ether, dinonyl ether, didecyl ether, diundecyl ether, etc. Preferably, dioctyl ether is used.

  Although said compound (b) can be used individually or in mixture of 2 or more types, Preferably the compounding quantity is 20 mass%-60 mass% in the total amount of inks obtained. Within the above range, the resulting ink has an effect on drying property and on-machine stability.

The compound (c) is a fatty acid ester represented by the following general formula (2).
R3COOR4 (2)
(R3 in the above formula represents an alkyl group or alkenyl group having 3 to 11 carbon atoms, and R4 represents an alkyl group having 5 to 14 carbon atoms.)
The compound (c) has an effect of adjusting the balance between the drying property of the ink obtained and the on-machine stability.

  Fatty acids constituting the fatty acid ester of the above compound (c) are coconut oil, palm oil, palm kernel oil, khair oil, red rice oil, rice bran oil, basket oil, guava oil, grapefruit seed oil, white These are plant-derived fatty acids such as sesame seed oil, shiromoji seed oil, date palm seed oil, and potato seed oil, and are generally composed of a plurality of fatty acids. To do. Examples of the fatty acid include butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, verargonic acid, capric acid, undecanoic acid, and undecylenic acid.

  Examples of the alcohol that reacts with the fatty acid to produce the compound (c) include, for example, amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, undecyl alcohol, dodecyl alcohol, tridecyl. Alcohol, tetradecyl alcohol, 3-methyl-butyl alcohol, 2-ethyl-1-butyl alcohol, 2,4-dimethyl-3-pentyl alcohol, 2-ethyl-1-hexyl alcohol, 3,5,5-trimethyl- Examples include 1-hexyl alcohol, 4-decyl alcohol, 2-isopropyl-5-methyl-1-hexyl alcohol, and 2-butyl-1-octyl alcohol.

  The compound (c) is synthesized by a known method such as a direct esterification reaction by reaction of the fatty acid and alcohol, a method of transesterification, a reaction of acyl chloride and alcohol, a reaction of epoxide and fatty acid. it can.

  Examples of the compound (c) include caproic acid heptyl ester, octyl ester, nonyl ester, decyl ester, 2-ethylhexyl ester, 3,5,5-trimethylhexyl ester, 4-decyl ester, 2-isopropyl-5. -Methylhexyl ester; hexyl ester of caprylic acid, heptyl ester, octyl ester, nonyl ester, 2,4-dimethyl 3-pentyl ester, 2-ethylhexyl ester, 3,5,5-trimethylhexyl ester; hexyl ester of capric acid And fatty acid esters such as 2-ethylbutyl ester and amyl ester.

The compound (c) can contain a compound (d) represented by the following general formula (3) for the purpose of finely adjusting the balance between the drying property and on-machine stability of the ink obtained. The compound (d) alone is not preferable because swelling of a rubber material of an ink roller or a blanket of a printing press appears.
R5COOR6 (3)
(R5 in the above formula represents an alkyl group or alkenyl group having 10 to 18 carbon atoms, and R6 represents an alkyl group having 1 to 4 carbon atoms.)

  When using the said compound (c) and the said compound (d) together, the compounding ratio of a compound (c) and a compound (d) is (d) :( c) = 1-10 mass%: 99-90 mass%. It is. When the compounding ratio of the compound (d) exceeds the above upper limit, there is a risk that swelling of the obtained ink with respect to a rubber material of an ink roller or a blanket on a printing press may be developed. On the other hand, when the blending ratio is less than the above lower limit, the effect of adjusting the balance between the drying property and the on-machine stability of the obtained ink cannot be obtained.

  The compound (d) is preferably a simple substance or a mixture of fatty acid esters derived from the vegetable oil represented by the general formula (3). Examples of the compound (d) include capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, margaric acid, stearic acid, and other methyl esters, ethyl esters, propyl esters, and isopropyl esters. , Butyl ester, isobutyl ester, tert-butyl ester and the like.

  The ink varnish used in the ink of the present invention comprises the resin for varnish (a), the solvent containing the compound (b) and the compound (c) in the above ratio, or the compound (d) with the compound (d ) Is blended so as to have the above blending ratio, and a gelling agent and vegetable oil are blended appropriately. As a method for preparing the varnish, for example, the resin for varnish (a), the compound (b), the compound (c), and if necessary, the compound (d) is blended with the compound (c), Prepared by heating and stirring the vegetable oil uniformly at 200 ° C. for 30 minutes in a nitrogen stream atmosphere, then cooling to 150 ° C., blending the gelling agent, and further heating and stirring uniformly at 200 ° C. for 60 minutes. To do.

  As said vegetable oil, well-known non-drying oil, semi-drying oil, drying oil, etc. can be used. As the above-mentioned non-drying oil, for example, castor oil, peanut oil, olive oil and the like, and as the semi-drying oil, for example, soybean oil, cottonseed oil, rapeseed oil, sesame oil, corn oil and the like, and as the dry oil, for example, , Linseed oil, eno oil, tung oil, etc., preferably soybean oil.

  Moreover, as said gelling agent, 1 type of well-known things can be used individually or in mixture of 2 or more types, for example, ethyl acetoacetate aluminum diisopropoxide, aluminum ethyl acetate diisopropylate , Aluminum tris (ethyl acetate), aluminum stearate, aluminum octylate, aluminum isopropylate, aluminum diisopropoxide, etc., preferably ethyl acetoacetate aluminum diisopropoxide. The above gelling agent can be obtained from Kawaken Fine Chemical Co., Ltd. under the trade name ALCH and used in the present invention.

  The ink of the present invention may be of an overprint varnish type in which no colorant is added to the varnish, but may be of a type containing a colorant in the varnish. In the ink production, for example, the varnish and the colorant are premixed with a mixer, then uniformly mixed with a three-roll mill, and the solvent of the varnish and the varnish are mixed until a desired ink tack is obtained. Prepare with additional formulation. Moreover, you may add additives, such as wax compounds, such as paraffin wax, polyethylene wax, and polytetrafluoroethylene wax, in the range which does not interfere with the objective of this invention as needed.

  Examples of the colorant used in the present invention include rake formation with inorganic pigments such as titanium oxide, calcium carbonate, barium sulfate, zinc white, petal, ultramarine, iron oxide, and aluminum powder, insoluble azo pigments, and metal salts. Azo pigment, condensed azo pigment, phthalocyanine pigment, anthraquinone pigment, chelate pigment, quinacridone pigment, thioindigo pigment, isoindolinone pigment, dioxazine pigment, quinophthalone pigment, perylene pigment, perinone pigment, indigo Pigments, pyranthrone pigments, anthanthrone pigments, flavanthrone pigments, diketopyrrolopyrrole pigments, isoindoline pigments, benzimidazolone pigments, anthraquinone pigments and other organic pigments, carbon black, and other dyes Can be mentioned.

  The ink of the present invention can be used as a lithographic printing ink for a single sheet, but is effectively used as an evaporation drying type offset rotary printing ink.

  Next, the present invention will be described more specifically with reference to preparation examples of ink varnishes R1 to R6 used in this example and ink varnishes S1 to S3 used in comparative examples, and ink examples and comparative examples using these ink varnishes. Explained. “Part” or “%” in the text is based on mass unless otherwise specified. In addition, this invention is not limited to the following Example.

(Ink varnishes R1 to R6)
As shown in Table 1, a resin for varnish (a), a compound (b), a compound (c), a compound (d), and a vegetable oil (e) are blended, and at 200 ° C. under a nitrogen stream. Heated and stirred uniformly for 30 minutes, then cooled to 150 ° C., blended with the gelling agent (f), and further heated and stirred uniformly at 200 ° C. for 60 minutes to prepare ink varnishes R1 to R6.

The varnish resin (a), compound (b), compound (c), compound (d), vegetable oil (e), and gelling agent (f) are as follows.
・ Resin for varnish (a)
As the rosin ester resin and rosin-modified phenol resin, the following production examples were used.
[Rosin ester resin (a1)]
To a reactor equipped with a stirrer and a thermometer, 800 parts of rosin and 200 parts of 1,3-pentadiene petroleum resin are added, heated to 200 ° C., and 50 parts of acrylic acid and 500 parts of maleic anhydride are added. Diene synthesis. To the reaction product, 130 parts of pentaerythritol and 0.5 part of magnesium oxide as a catalyst were added and subjected to esterification reaction at 280 ° C. to give a rosin ester resin (a1) having a weight average molecular weight of 100,000 and a cloud point of 120 ° C. Manufactured.
[Rosin-modified phenolic resin (a2)]
A reactor equipped with a stirrer, reflux condenser and thermometer was charged with 47 parts of toluene, 320 parts of p-octylphenol, and 101 parts of 92% paraformaldehyde, heated to 60 ° C. and dissolved, and then 8 parts of sodium hydroxide. . Next, the reaction was performed by heating to 90 ° C., and then water was separated and removed to obtain a resole resin having an average number of nuclei of 3. Next, in a reaction apparatus equipped with a stirrer, a reflux condenser with a water separator, and a thermometer, 600 parts of gum rosin was dissolved in a nitrogen atmosphere, and the above-mentioned resol resin was added. The rosin-modified phenol resin (a2) having a weight average molecular weight of 100,000 and a cloud point of 100 ° C. Manufactured.

[Compound (b)]
Dioctyl ether [compound (c)]
c1: caprylic acid 2-ethylhexyl ester c2: caproic acid 4-decyl ester c3: capric acid n-hexyl ester [compound (d)]
Lauric acid isopropyl ester

[Vegetable oil (e)]: soybean oil [gelling agent (f)]: ethyl acetoacetate aluminum diisopropoxide (ALCH from Kawaken Fine Chemical Co., Ltd.)

(Ink varnish S1 to S3)
As shown in Table 1, each component used in the examples or petroleum solvent (P1 or P2) was blended, and heated and stirred uniformly at 200 ° C. for 30 minutes under a nitrogen stream, and then heated to 150 ° C. After cooling, the gelling agent (f) was blended and further heated and stirred at 200 ° C. for 60 minutes to prepare ink varnishes S1 to S3. The petroleum solvents (P1, P2) are as follows.
・ Petroleum solvent P1: AF solvent No. 7 ・ Petroleum solvent P2: AF solvent No. 5 (high boiling point)

[Examples 1 to 6]
Each of the ink varnishes R1 to R6 is used, and phthalocyanine blue is blended in each ink varnish as shown in Table 2, and uniformly kneaded by a known method so that the ink tack becomes 10 to 11 in the incometer measurement value. In addition, the solvent used in the preparation of the ink varnish and the varnish were additionally blended and uniformly kneaded by a known method to prepare inks T1 to T6 of the present invention. The above ink tack value is obtained by applying 1.31 ml of the obtained ink to a roll of an incometer manufactured by Toyo Seiki Co., Ltd., rotating at a roll temperature of 32 ° C., and a rotation speed of 1,200 rpm. It is.

[Comparative Examples 1-3]
Each of the ink varnishes S1 to S3 is used, and phthalocyanine blue is blended in each varnish as shown in Table 2 and uniformly kneaded by a known method, so that the ink tack becomes 10 to 11 in an incometer measurement value. Thus, the solvent used for the preparation of the varnish and the varnish were additionally blended and uniformly kneaded by a known method to prepare comparative inks U1 to U3. The ink U1 of the comparative example is a standard composition ink that has been conventionally used.

Each ink obtained above was evaluated by the following measuring methods with respect to drying property, on-machine stability, suitability for rubber material, and environmental compatibility. The evaluation results are shown in Table 3 and Table 4.
(Drying)
Using 0.125 ml of each of the above inks as a sample, the sample was printed on topcoat paper using a RI tester 2-split roll manufactured by Ishikawajima Sangyo Co., Ltd., and a printed sample piece was prepared. Next, using an oven with adjustable temperature conditions, the printed sample piece is heated, and the ink coating film is dried and solidified while manipulating the paper surface temperature. After drying, the print sample piece is allowed to cool for 1 minute, and the ink coating surface of the cooled print sample piece is rubbed with a white paper set in a Gakushin type frictional resistance tester, and the print sample piece is rubbed. The paper surface drying temperature when not falling off was measured. The drying property indicates that the lower the paper surface drying temperature, the better the ink drying property, while the higher the paper surface drying temperature, the poorer the ink drying property.

(Onboard stability)
Apply 0.5 ml of each of the above inks to an incometer manufactured by Toyo Seiki Co., Ltd., set the roll temperature to 32 ° C and the rotation speed to 2,000 rpm, rotate the roll, and measure the change in tack value over time. To do. Read the elapsed time (stabilization time) from the start of measurement until the ink on the roll loses tackiness and the tack value starts to decrease, and the stability of the ink is evaluated. The longer the time, the better the stability.

(Applicability to rubber material)
Apply a suitable amount of each of the above inks to the surface of a rubber blanket piece (manufactured by Deinternational, Dibran 3000-4), leave it at room temperature for 24 hours, wipe off the ink, and suit the rubber material according to the swelling of the blanket surface. The larger the occurrence of swelling and softening phenomenon, the worse the suitability for the rubber material, while the smaller the phenomenon, the better the suitability for the rubber material.
◯: No swelling or softening phenomenon is observed on the blanket surface, and suitability for rubber materials is good.
Δ: Swelling or softening phenomenon is slightly recognized on the blanket surface in a range where there is no practical problem, and suitability for a rubber material is in a range where there is no practical problem.
X: Swelling or softening phenomenon is recognized on the blanket surface, and suitability for rubber material is inferior.

(Environmental compatibility)
The degree of consideration for environmental compatibility of each ink obtained was evaluated by a 10-point method. The larger the evaluation score, the less the use of petroleum-based raw materials in the solvent used and the varnish resin, and the better the degree of environmental consideration. On the other hand, the smaller the evaluation score, the more use of petroleum-based raw materials in the above components. Indicates that the degree of environmental consideration is inferior.

  From the above evaluation results, the ink of the present invention has better drying and on-machine stability than inks using conventional petroleum solvents, and does not swell to rubber materials, even if no petroleum solvents are used. It has been proved that the environmental compatibility is greatly improved while having the feature that there are few.

  The ink of the present invention does not contain any petroleum-based solvent, has better drying and on-machine stability than varnishes and inks using conventional petroleum-based solvents, and is suitable for rubber materials on printing presses. Is excellent and the environmental compatibility is greatly improved, it can be effectively used as an environmentally friendly lithographic printing ink, especially as an offset rotary printing ink.

Claims (6)

The resin for varnish (a) which has rosin ester resin as a main component and a solvent are contained, and this solvent is represented by the compound (b) represented by the following general formula (1) and the following general formula (2). A lithographic printing ink comprising a compound (c) in a ratio of (c) :( b) = 0 to less than 30% by mass: 100 to 70% by mass and containing no petroleum solvent.
R1-O-R2 (1)
(R1 in the above formula represents an alkyl group or alkenyl group having 4 to 22 carbon atoms, and R2 represents an alkyl group having 1 to 22 carbon atoms.)
R3COOR4 (2)
(R3 in the above formula represents an alkyl group or alkenyl group having 3 to 11 carbon atoms, and R4 represents an alkyl group having 5 to 14 carbon atoms.) The ink according to claim 1, wherein the compound (c) contains a compound (d) represented by the following general formula (3).
R5COOR6 (3)
(R5 in the above formula represents an alkyl group or alkenyl group having 10 to 18 carbon atoms, and R6 represents an alkyl group having 1 to 4 carbon atoms.)   The ink according to claim 2, wherein the compounding ratio of the compound (c) and the compound (d) is (d) :( c) = 1 to 10% by mass: 99 to 90% by mass.   The ink according to claim 1, wherein the rosin ester resin has a cloud point of 50 ° C. to 200 ° C. and a weight average molecular weight of 20,000 to 500,000.   Furthermore, the ink of any one of Claims 1-4 containing a coloring agent.   It is an offset rotary printing ink, The ink of any one of Claims 1-5.