JP2000159867A - Resin for printing ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin which is formaldehyde-free and gives a printing ink improved in offset printing characteristics and printing workability by esterifying polymerized rosin and dimer acid with a polyhydric alcohol. SOLUTION: To a mixture of 100 pts.wt. polymerized rosin having a softening point of 90-140 deg.C and an acid value of 140-160 with 1-200 pts.wt. dimer acid, added is 0.5-1.5 equivalents, desirably, 0.8-1.2 equivalents, per equivalent of the carboxylic acids of the polymerized rosin and the dimer acid, of a polyhydric alcohol. The resultant mixture is esterified at 230-290 deg.C, desirably, 250-270 deg.C for 5-15 h, desirably, 7-10 h in the presence of a catalyst such as magnesium oxide, zinc oxide, or calcium oxide and, optionally, a silicone antifoam to obtain a resin for a printing ink. This resin is mixed with a drying oil such as linseed oil or tung oil, a solvent, a pigment, and, optionally, a gelling agent, a fatty acid ester, etc., to obtain a printing ink.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a printing ink resin having excellent ink performance and printing workability in offset printing, and a printing ink using the printing ink resin.

[0002]

2. Description of the Related Art Offset printing is a typical printing method widely used for printing. This method includes a heat-set offset rotary printing in which ink is dried by heat and a sheet-fed printing method in which drying oil is cured and dried using a catalyst. Generally, a rosin phenol resin obtained by modifying rosin, which is a natural product, with a phenol resin, particularly a resol resin, is used as a resin constituting the ink used for the printing.

[0003] The rosin phenol resin has an advantage that by having rosin in the resin skeleton, the wettability with the pigment is improved and the pigment is easily dispersed uniformly. The reason that this rosin is modified with phenol is that rosin itself is a monocarboxylic acid that does not cause polymer polymerization, and therefore it is necessary to introduce a crosslinked structure.

[0004] Further, since phenol and formaldehyde and an alkali or acid catalyst are used in the synthesis of phenol resin, formaldehyde is an essential component in the synthesis of rosin phenol resin.

However, in the heat-set type offset printing, a considerable amount of heat is applied to the printing ink. Depending on the heat, unreacted formaldehyde remaining in the rosin phenol or formaldehyde derived from the terminal methylol group of the resole may be used. The possibility of release from the skeleton cannot be denied. This formaldehyde has been pointed out as a compound causing chemical substance hypersensitivity which has been taken up by the sick house problem and the like, and development of a resin that suppresses the release of formaldehyde is demanded.

[0006] As a method for suppressing the release of formaldehyde, first, a method of adding a so-called catcher having a formaldehyde trapping ability to a conventional resin system containing formaldehyde, and second, no formaldehyde is used in the synthesis process. A method using a resin is considered.

[0007] However, in the former, it is difficult to adjust the workability at the time of forming the ink, and in the first place, it is considered that formaldehyde derived from the terminal methylol is liberated with time, and it is difficult to catch with a catcher alone. .

On the other hand, with respect to the latter resin which does not use formaldehyde in the synthesis process, there are only a limited number of resins satisfying the properties as a resin for ink, and it is preferable to contain rosin. Polymerized rosin can be mentioned as having rosin in the skeleton and being crosslinkable. Polymerized rosin is a dibasic acid compound obtained by heat polymerization of rosin, and enables high-molecular polymerization by an esterification reaction with a polyhydric alcohol. This resin is called “natural resin turpentine oil / tall oil” (W. Thunderman, December 20, 1986, No. 2)
Press) has already been reported.

However, when the resin obtained by the esterification reaction of the polymerized rosin and the polyhydric alcohol is applied to a resin for ink, there is a disadvantage that the compatibility with solvents added at the time of ink formation is very poor. This is because this polymerized rosin esterification reaction product contains many ester bonds in the molecular chain and has a very high polarity.On the other hand, linseed oil or a petroleum-based solvent which is a drying oil to be added at the time of ink formation is used. However, since both are non-polar, there arises a problem that the solubility of the resin is extremely poor due to the difference in polarity.

Further, in offset printing, ink is transferred from a plate to a support such as paper by utilizing the repulsion of water and oil, so that it has a proper affinity for water and oil. Specifically, the ink is exposed to water containing a small amount of isopropyl alcohol, called immersion water. Therefore, if the affinity for water is too good, the resin is so emulsified that the resin is soaked and dissolved in water, so-called bleeding occurs. Conversely, if the affinity with water is too low, there arises a problem that ink transfer does not occur. The above-mentioned polymerized rosin esterification reaction product has a problem that the bleeding phenomenon easily occurs because the polarity is too strong.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a novel printing ink resin which does not contain any formaldehyde and has good offset printing characteristics. It is in.

[0012]

According to the present invention, a mixture containing a polymerized rosin and a dimer acid is mixed with a polyhydric alcohol in an amount of 0.5 to 1 to 1 equivalent of the carboxylic acid of the polymerized rosin and the dimer acid. The present invention relates to a printing ink resin obtained by adding 5 equivalents and performing an esterification reaction.

Further, the present invention relates to a polymerized rosin having a weight ratio of 7%.
The following unsaturated polybasic acid is added, and a mixture containing modified polymerization and dimer acid obtained by the addition reaction is added to the modified polymerized rosin and 1 equivalent of the carboxylic acid of the dimer acid.
The present invention relates to a printing ink resin obtained by adding a polyhydric alcohol at a ratio of 0.5 to 1.5 equivalents and performing an esterification reaction.

The present invention further relates to a mixture containing 100 parts by weight of a polymerized rosin and 1 to 200 parts by weight of a dimer acid, wherein 0.5 equivalent of a polyhydric alcohol is added to 1 equivalent of the carboxylic acid of the polymerized rosin and the dimer acid. The present invention relates to a resin for printing ink obtained by adding at a ratio of about 1.5 equivalents and performing an esterification reaction.

Further, the present invention relates to a polymerized rosin having a weight ratio of 7%.
The following unsaturated polybasic acids are added, and 100 parts by weight of a modified polymerized rosin obtained by an addition reaction and dimer acids 1 to 200
Parts by weight of a polyhydric alcohol with respect to 1 equivalent of the carboxylic acid of the polymerized rosin and the dimer acid.
The present invention relates to a resin for printing ink obtained by adding 5 to 1.5 equivalents and performing an esterification reaction.

Further, the present invention relates to a printing ink comprising the above-mentioned resin for printing ink, drying oil, solvent and pigment as essential components.

The resin for printing inks of the present invention uses polymerized rosin instead of rosin, which is a monocarboxylic acid, which has been conventionally used, so that it is not necessary to carry out modification with phenol which may release formaldehyde. Has a cross-linking property.

Furthermore, an esterification reaction product obtained by simply esterifying a polymerized rosin with a polyhydric alcohol has too high a polarity as an ink resin, but is obtained by esterifying a mixture of a polymerized rosin and a dimer acid. Since the long-chain alkyl is introduced in a pendant manner into the resin skeleton of the esterification reaction product, the polarity can be optimally controlled.

Such a printing ink resin has the advantage of having offset printing characteristics and workability, although it is a formaldehyde-free resin that has not existed conventionally.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The polymerized rosin used in the present invention is:
It refers to one obtained by polymerizing rosin to increase the melting point, usually having a softening point of 90 to 140 ° C and an acid value of 140 to 160. Although not particularly limited to the following compounds, for example, polymerized rosin manufactured at Wupulin Forestry Factory in Fujian Province, China, and polymerized rosins # 115, # 130, and # 1 manufactured at Guilin Chemical Factory, China
40, # 150, POLY made by RESITEC, Brazil
GUMRESIN and the like.

It is a preferred embodiment of the present invention to use a modified polymerized rosin obtained by adding an unsaturated polybasic acid at a weight ratio of 7% or less and performing an addition reaction instead of the polymerized rosin.

Examples of the unsaturated polybasic acids include unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid, and unsaturated polycarboxylic acids such as maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride and cinnamic acid. Dicarboxylic acid and the like.

Since the polymerized rosin has an unsaturated bond, the modified polymerized rosin is obtained by adding an unsaturated polybasic acid by an addition reaction such as an ene reaction or a Diels-Alder reaction. Examples of the conditions for the addition reaction include the following conditions.

The rosin is melted at 200 ° C. and the unsaturated polybasic acid is added all at once or gradually. After the melting, the temperature is maintained for about one hour to complete the addition reaction.

At the time of this addition reaction, it is possible to add a petroleum resin or the like as an extender. For example, examples of such an extender include petroleum resin Marcarez T200A (manufactured by Maruzen Petrochemical Co., Ltd.) and Quinton 1325 (manufactured by Nippon Zeon Co., Ltd.).

By modifying the polymerized rosin with an unsaturated polybasic acid in this manner, the resin is likely to have a crosslinked structure and the molecular weight is increased, so that the viscosity of the ink when formed into an ink is increased and the workability is improved. it can.

The weight of the unsaturated polybasic acid added at the time of the addition reaction is limited to 7% by weight or less based on the polymerized rosin. This is because there is a possibility of gelling during the esterification reaction with the dihydric alcohol. The weight of the unsaturated polybasic acid to be added is preferably 1% by weight or more. this is,
This is because, when the viscosity increasing effect due to the modification of the unsaturated polybasic acid is taken into consideration, an effective effect appears at 1% by mass or more.

The dimer acid is obtained by subjecting a fatty acid to heat dimerization in the presence of a catalyst such as clay. As fatty acids, those obtained from drying oils such as tall oil and soybean oil, and semi-drying oils are used. Although not particularly limited to the following compounds,
Harima Dimer DA-270S, D manufactured by Harima Chemicals, Inc.
A-250, DA-200K and the like.

Hereinafter, a method for preparing a resin for a printing ink will be described.

The mixing ratio of the dimer acid to 100 parts by weight of the polymerized rosin is preferably 1 part by weight or more in consideration of the compatibility of the printing ink resin to be synthesized with a solvent or the like. In order to control the point not to be too low, the content is preferably 200 parts by weight or less.

Therefore, in order to further improve the softening point of 100 parts by weight of the polymerized rosin and 1 to 200 parts by weight of the dimer acid, a polyhydric alcohol is added to a mixture containing 1 to 50 parts by weight to carry out the esterification reaction. Do.

The amount of the polyhydric alcohol to be added is preferably 0.5 to 1.5 equivalents to 1 equivalent of the carboxylic acid of the polymerized rosin and dimer acid in the above mixture, and more preferably 0 to 1.5 equivalents. A ratio of 0.8 to 1.2 equivalents is preferred, most preferably 0.9 to 1.1 equivalents.

When the modified polymer rosin is used in place of the polymerized rosin, 100 parts by weight of the modified polymerized rosin and 1 to 200 parts by weight of the above dimer acid are further improved for the same reason as in the case of the polymerized rosin. Has 1 to
A polyhydric alcohol is added to the mixture containing 50 parts by weight to carry out an esterification reaction.

The amount of the polyhydric alcohol to be added is 0.5 to 0.5% based on 1 equivalent of the carboxylic acid of the modified polymer rosin and the dimer acid in the above mixture, just like the case of the polymer rosin.
It is preferable to add 1.5 equivalents, more preferably 0.8 to 1.2 equivalents, and most preferably 0.9 to 1.1 equivalents.

As the catalyst for carrying out the esterification reaction,
Magnesium oxide, zinc oxide, calcium oxide, or the like can be used.

The reaction temperature is from 230 to 29.
0 ° C. is suitable, and especially 250-270 ° C. is optimal. The reaction time in this temperature range is 5 to 15 hours, preferably 7 to 10 hours.

A silicone-based antifoaming agent can be added to a mixture of polymerized rosin (or modified polymerized rosin) and dimer acid for the purpose of defoaming bubbles generated during the esterification reaction.

Further, solvents such as No. 0 solvent (manufactured by Nippon Petrochemical Co., Ltd.) and AF Solvent (manufactured by Nippon Petrochemical Co., Ltd.), turpentine oil and the like can be appropriately added to the above mixture. This makes it easier to take out the resin from the reactor at the end of the reaction.

The above additives such as a defoaming agent and a solvent can be appropriately added even during the esterification reaction.

By the above synthesis reaction, the resin for printing ink of the present invention can be prepared. Next, the ink using the printing ink resin will be described.

The ink is prepared by blending the printing ink resin, drying oil, solvent and pigment of the present invention.

Examples of the drying oil include linseed oil and tung oil. Moreover, although it is a semi-dry oil, soybean oil etc. are mentioned. In these, the drying oil is polymerized after printing by a catalyst called a dryer, and the film is cured.

The solvent is added to adjust the viscosity of the ink and to speed up the drying property after printing.
No. 0 Solvent S, No. 0 Solvent H, AF Nos. 4 to 7 Solvent (all manufactured by Nippon Petrochemical Co., Ltd.) and the like.

The pigment is used for coloring the printing material, and pigments such as yellow, red, indigo or black are selected as necessary.

In addition, the addition of a gelling agent for the purpose of imparting a gel taste to the ink and improving the printing characteristics, and the addition of a fatty acid ester for the purpose of improving the printing gloss after printing are not described in the present invention. This is a preferred embodiment of the present invention.

The following examples illustrate the invention in more detail.

Example 1 In a reaction vessel, 500 g of polymerized rosin # 140 (acid value: 148) and 60 g of petroleum resin T200A (manufactured by Maruzen Petrochemical Co., Ltd.) from Guilin Chemical Works, China were dissolved, and anhydrous maleic was further dissolved. 20 g of an acid was added and maleation was performed to prepare a modified polymerized rosin.

Next, in this reaction vessel, 50 g of dimer acid (Halidimer DA200K: manufactured by Harima Chemicals, Inc.)
Was added, and modified polymerized rosin and dimer acid were mixed. To this mixture, 46.6 g of pentaerythritol and 17.6 g of glycerin were added as polyhydric alcohols, and 0.5 g of magnesium oxide was further added as an esterification catalyst. Further, the reaction vessel was heated to 270 ° C. to perform an esterification reaction, thereby obtaining a resin of the present invention. Table 1 shows the properties of the resin.
Shown in The evaluation methods in Table 1 were performed as follows. Flaxseed oil viscosity (Gardner bubble type viscosity): Flaxseed oil and the above resin were blended at a weight ratio of 2: 1 and the mixture was heated and dissolved, and measured by a Gardner bubble type viscometer. Hexane tolerance: flaxseed oil and the above resin in a weight ratio of 2:
Normal hexane was added to the mixture which was blended at a ratio of 1 and dissolved by heating, and the ratio of the amount of hexane required for cloudiness was measured. No. 0 solvent solubility: The above resin and the No. 0 solvent were dissolved and the weight% of the minimum amount of resin that did not become cloudy when heated to 25 ° C. was measured. Weight average molecular weight: The molecular weight in terms of polystyrene measured by GPC.

[0049]

[Table 1] Then, the obtained resin was finely crushed, and 40 parts by weight of the crushed resin, 20 parts by weight of linseed oil, and 40 parts by weight of AF6 solvent were put in a reaction vessel, and the temperature was increased while blowing nitrogen gas, followed by stirring at 200 ° C. While keeping the temperature for 30 minutes, a varnish was obtained. The obtained varnish was cooled to 100 ° C., and a gelling agent was added. The gelling agent used was prepared by diluting 1.4 parts by weight of AlCH (manufactured by Kawaken Fine Chemicals Co., Ltd.) with 1.4 parts by weight of AF6 solvent. Further, the temperature was raised to 200 ° C. again and kept for 1 hour to obtain a gel varnish for ink.

Next, 60 parts by weight of the obtained gel varnish and 18 parts of carmine 6B (manufactured by Toyo Ink Mfg. Co., Ltd.) as a red pigment were dispersed using a three-roll mill, and
Solvent F6 and gel varnish were added so that the total amount was 100 parts by weight, and then 0.5 part by weight of a 6% manganese naphthenate solution (dryer manufactured by Harima Chemicals, Inc.) was added. Prepared to be 33-35,
A printing ink was obtained. Table 2 shows the properties of the ink. Table 2 also shows the measurement results of the physical properties of the examples and comparative examples, as well as the optimum ranges for the physical properties.

The characteristics evaluation methods shown in Table 2 were performed as follows. Gloss value: 0.3 cc of the ink was spread on art paper with a full-scale roll of an RI tester (manufactured by Akira Seisakusho Co., Ltd.). After 24 hours, the gloss value was measured with a 60 ° -60 ° gloss meter.

Set: 0.1 cc of ink was spread with 4 cut rolls of RI tester (manufactured by Akira Seisakusho Co., Ltd.), and then
Cut the exhibition color, paste it on another art paper, RI
Using a roll of a tester, the time (minute) until the ink did not adhere to the art paper was measured. In a normal evaluation, 12 to 21 minutes is optimal. If the time is shorter than 12 minutes, the storage stability of the ink is often poor. If the time is longer than 21 minutes, show-through is likely to occur when the printed matter is overlaid. know. Drying property on paper: 0.1cc of ink was applied to RI tester (Ltd.)
After spreading on sulfuric acid paper with a 4-cut roll (made by Mei Seisakusho Co., Ltd.), the sulfuric acid paper was overlaid and set on a Chaoyangkai dry tester.
The drying time was compared under the condition of 1 rpm. The evaluation criteria shown in Table 2 are as follows. A: The drying time is 0 or more and less than 4 hours. The best level. Good: The drying time is 4 or more and less than 7 hours. A good level. C: The drying time is 7 or more and less than 10 hours. Normal level. X: The drying time is 10 hours or more. Inappropriate level. Ink viscosity and yield value: L-type viscometer (Toyo Seiki Co., Ltd.)
Manufactured). Flow 60s: The spread (diameter) of the ink was measured with a spread meter manufactured by Rikaisha Co., Ltd. Maximum emulsification amount: Lisodronic emulsification tester (Novocontrol
At 40 ° C. and 25 g of ink at 40 ° C.
Water was added at a rate of ml / min, and the water content at the time when the ink was saturated was measured. (Rotation speed of emulsification tester: 1200r
pm)

[0053]

[Table 2] As a result of the evaluation, it was found that an ink having the same performance as that of the ink using phenol-modified rosin (conventional resin) shown in Comparative Example 4 was obtained.

Example 2 A modified polymerized rosin was synthesized under the same conditions as in Example 1. Further, an esterification reaction was carried out in exactly the same manner as in Example 1, except that 63.8 g of pentaerythritol was added as a polyhydric alcohol. Table 1 shows the properties of the resin.

Using this resin, an ink was prepared in the same manner as in Example 1. Table 2 shows the properties of this ink.

Example 3 In a reaction vessel, 500 g of polymerized rosin # 140 (acid value: 148) and 60 g of petroleum resin T200A (manufactured by Maruzen Petrochemical Co., Ltd.) were dissolved in Guilin Chemical Works, China.

Next, 55 g of dimer acid (Haridimer DA200K: manufactured by Harima Chemicals, Inc.) was placed in the reaction vessel.
And polymerized rosin and dimer acid are mixed, and pentaerythritol 5 as a polyhydric alcohol is added to the mixture.
3.1 g were further added, and 0.5 g of magnesium oxide was further added as an esterification catalyst. Further, this reaction vessel was heated to 270 ° C. to carry out an esterification reaction to obtain a resin of the present invention. Table 1 shows the properties of the resin.

Further, using this resin, an ink was prepared in the same manner as in Example 1. Table 2 shows the properties of this ink.

Comparative Example 1 In a reaction vessel, 500 g of polymerized rosin # 140 (acid value: 148) and 20 g of petroleum resin T200A (manufactured by Maruzen Petrochemical Co., Ltd.) from Guilin Chemical Works, China were dissolved, and further anhydrous maleic anhydride was added. 16.5 g of acid was added, and maleation was performed to prepare a modified polymerized rosin.

Next, in this reaction vessel, 68.7 g of pentaerythritol as a polyhydric alcohol was added, and 0.15 g of zinc oxide was further added as an esterification catalyst. Further, the reaction vessel was heated to 270 ° C. to carry out an esterification reaction to obtain a resin. Table 1 shows the properties of the resin.
It is shown in Table 1. Linseed oil viscosity is as low as Z _1, an ink reduction was impossible.

[Comparative Example 2] In a reaction vessel, 500 g of polymerized rosin # 140 (acid value: 148) and 60 g of petroleum resin T200A (manufactured by Maruzen Petrochemical Co., Ltd.) from Guilin Chemical Works, China were dissolved, and anhydrous maleic acid was further dissolved. 40 g of an acid was added, and maleation was performed to prepare a modified polymerized rosin.

Then, in this reaction vessel, 50 g of dimer acid (Halidimer DA200K: manufactured by Harima Chemicals, Inc.)
Was added, and the modified polymerized rosin and dimer acid were mixed. To this mixture, 63.8 g of pentaerythritol as a polyhydric alcohol was added, and 0.5 g of zinc oxide was further added as an esterification catalyst. Further, this reaction vessel is
When the esterification reaction was carried out by heating to ° C., the amount of maleic anhydride was too large to cause gelation.

Comparative Example 3 500 g of Chinese gum rosin X grade (acid value 170) and petroleum resin T2 were placed in a reaction vessel.
Then, 60 g of 00A (manufactured by Maruzen Petrochemical Co., Ltd.) was dissolved, and 20 g of maleic anhydride was further added, followed by maleation to prepare a modified polymerized rosin.

Next, 50 g of dimer acid (Haridimer DA200K: manufactured by Harima Chemicals, Inc.) was placed in the reaction vessel.
Was added, and the modified polymerized rosin and dimer acid were mixed. To this mixture, 50.8 g of pentaerythritol and 19.2 g of glycerin were added as polyhydric alcohols, and 0.5 g of zinc oxide was further added as an esterification catalyst. Further, the reaction vessel was heated to 270 ° C. to carry out an esterification reaction to obtain a resin.

Table 1 shows the properties of the resin. It is shown in Table 1. Linseed oil viscosity was as low as V-W, and ink formation was impossible.

Comparative Example 4 An ink was prepared in exactly the same manner as in Example 1 except that rosin phenol resin Hariphenol 173 (manufactured by Harima Chemicals, Inc.) was used as the resin for the printing ink. Table 2 shows the properties of this ink.

[0067]

According to the present invention, by esterifying a mixture of polymerized rosin and dimer acid, a resin for printing ink having offset printing characteristics and workability, which is a formaldehyde-free resin which has never existed before. Can be provided.

Continued on the front page (72) Inventor Noriaki Hata 5-9-3 Tokodai, Tsukuba-shi, Ibaraki Harima Chemicals Co., Ltd. Tsukuba Research Laboratory F-term (reference) 4J029 AA07 AB01 AB04 AC02 AE18 BA02 FC03 FC05 FC08 GA44 HA01 HB01 4J039 AB04 AB08 BE01 GA02

Claims (7)

[Claims] 1. A mixture containing a polymerized rosin and dimer acid, and a polyhydric alcohol is added in a ratio of 0.5 to 1.5 equivalents to 1 equivalent of the carboxylic acid of the polymerized rosin and dimer acid to form an ester. A resin for printing ink obtained by a chemical reaction. 2. A mixture containing a modified polymerized rosin and dimer acid obtained by adding an unsaturated polybasic acid having a weight ratio of 7% or less to a polymerized rosin, and adding the modified polymerized rosin and the dimer acid to the mixture. A resin for a printing ink obtained by adding 0.5 to 1.5 equivalents of a polyhydric alcohol to 1 equivalent of the carboxylic acid of the above, followed by an esterification reaction. 3. A mixture containing 100 parts by weight of a polymerized rosin and 1 to 200 parts by weight of a dimer acid, a polyhydric alcohol is added in an amount of 0.5 to 1 to 1 equivalent of the carboxylic acid of the polymerized rosin and the dimer acid. A resin for printing ink obtained by adding 5 equivalents and performing an esterification reaction. 4. A mixture containing 100 parts by weight of a modified polymerized rosin obtained by adding an unsaturated polybasic acid having a weight ratio of 7% or less to the polymerized rosin and performing an addition reaction, and 1 to 200 parts by weight of a dimer acid, The polyhydric alcohol is added in an amount of 0.5 to 1.5 with respect to 1 equivalent of the carboxylic acid of the modified polymer rosin and the dimer acid.
Resins for printing inks obtained by an esterification reaction when added in equivalent amounts. 5. The method according to claim 1, wherein the unsaturated polybasic acid is acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid,
The printing ink resin according to claim 2 or 4, wherein the resin is at least one unsaturated carboxylic acid selected from the group consisting of itaconic acid, itaconic anhydride and cinnamic acid. 6. The polyhydric alcohol according to claim 1, wherein the polyhydric alcohol is at least one polyhydric alcohol selected from the group consisting of glycerin, trimethylolpropane, diethylene glycol, pentaerythritol, and dipentaerythritol. 6. The printing ink resin according to any one of 5. 7. A printing ink comprising the resin for a printing ink according to any one of claims 1 to 6, a drying oil, a solvent and a pigment as essential components.