JP2007169574A - Printing ink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink in which a part of a petroleum-based solvent is changed to the solvent of a specific vegetable origin, and thereby the printability of the ink is not spoiled and a high luster printed matter can be obtained in an offset rotary printing ink. <P>SOLUTION: The offset rotary printing ink includes a resin for a varnish and a solvent, wherein the solvent contains 0.1-30 mass% of a fatty acid ester expressed by following general formula (1): R1COOR2. In general formula (1), R1 represents a 3-11C alkyl group or alkenyl group, and R2 represents a 5-14C alkyl group. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an offset rotary printing ink from which high gloss prints can be obtained. Specifically, by replacing a part of petroleum-based solvent with a solvent derived from a specific plant, the printability such as ink drying property and image reproducibility is provided. The present invention relates to an offset rotary printing ink that can provide a high-gloss printed matter without impairing (hereinafter simply referred to as printability).

  2. Description of the Related Art Conventionally, in rotary offset printing, an offset rotary printing ink that can supply a highly glossy printed matter has been desired for the purpose of improving printing quality. Conventionally, as a prescription to improve the gloss of printed matter, by reducing the viscosity of the ink to improve the smoothness of the printing surface or increasing the resin component in the ink system, the penetration of the ink into the printing paper is suppressed as much as possible. In order to maintain the ink film thickness, a prescription has been used.

  In the above formulation, in order to lower the viscosity of the ink, there is a formulation in which the amount of low viscosity components such as petroleum solvent and vegetable oil in the ink system is increased. Moreover, in order to increase the resin component in an ink system, the prescription | regulation which takes in as many resin components as possible in an ink system using a low molecular highly soluble resin, petroleum resin, etc. is mentioned.

  However, the above-mentioned prescription for decreasing the viscosity of the ink tends to decrease the resin component in the ink system, and the prescription for increasing the resin component in the ink system tends to increase the ink viscosity. The properties to reduce the gloss improvement effect by half. Further, such a formulation has a tendency to greatly inhibit the printability of the ink, and there is a limit to improving the gloss of the printed matter while maintaining the printability.

  In addition to the above prescriptions, by using a class of petroleum solvents that are highly soluble in the resin components in the ink system, the compatibility in the ink system is increased to lower the viscosity of the ink and increase the concentration of the resin component. There is also a prescription. However, the gloss effect cannot be sufficiently obtained with the solubility of the above-described petroleum-based solvent in the resin. In addition, most of the above petroleum-based solvents are mainly composed of aromatic hydrocarbons, which have a large adverse effect on the human body, and they have recently been used in printing due to environmental impacts such as the printing work environment and air pollution. I have forgotten.

  For this reason, an offset ink composition having excellent setability and gloss has been developed by using a vegetable oil component instead of a petroleum solvent (Patent Document 1). Such an offset ink composition is substantially free of a mineral oil component and uses only a vegetable oil component as a solvent component. As the vegetable oil component, a fatty acid having 16 to 20 carbon atoms and a carbon atom having 1 to 10 carbon atoms are used. It is described that fatty acid monoesters of alcohol can be used. However, when only such a fatty acid monoester is used as the ink solvent, depending on the printing method, there has been a situation in which it is not satisfactory in terms of the drying property of the ink. Therefore, development of an ink having excellent drying properties and further having a gloss improvement effect has been demanded.

  In view of the above, there is a demand for an offset rotary printing ink that can obtain a printed matter having sufficient gloss without impairing the printability of the ink.

JP 2003-31482 A

  Accordingly, an object of the present invention is to obtain a high gloss printed matter without impairing the printability of the ink by substituting a part of petroleum-based solvent with a specific plant-derived solvent in offset rotary printing ink (hereinafter simply referred to as ink). It is to provide the resulting ink.

The above object is achieved by the present invention described below. That is, the present invention is an ink characterized in that it contains a resin for varnish and a solvent, and the solvent contains 0.1 to 30% by mass of a fatty acid ester represented by the following general formula (1). is there.
R1COOR2 (1)
(In the general formula (1), R1 represents an alkyl group or alkenyl group having 3 to 11 carbon atoms, and R2 represents an alkyl group having 5 to 14 carbon atoms.)

  As a result of intensive studies to solve the above problems, the present inventors have found that an ink containing the above fatty acid ester in an amount that occupies less than 0.1 to 30% by mass of the total amount of the solvent is a conventional ink. It was found that a highly glossy printed matter can be obtained without impairing the printability of the ink.

  According to the present invention, by replacing the petroleum solvent in the ink with the fatty acid ester having the above composition structure, the solubility in the resin component in the ink system becomes very high, the ink has a low viscosity, and Since the resin component can be increased, a printed matter with higher gloss can be obtained. Furthermore, since it is not necessary to significantly manipulate the resin composition or plastic component in the ink system, a highly glossy printed matter can be obtained without impairing the printability of the ink. Moreover, since petroleum-based solvent can be reduced from the ink by using the above-mentioned plant-derived solvent, an ink with less environmental impact than conventional ink is provided.

  Next, the present invention will be described in more detail with reference to preferred embodiments. The solvent that mainly characterizes the present invention contains the fatty acid ester represented by the general formula (1) in an amount that occupies less than 0.1 to 30% by mass in the total amount of the solvent.

  In the general formula (1), R1 represents an alkyl group or an alkenyl group having 3 to 11 carbon atoms, and R2 has 5 to 5 carbon atoms. It is a fatty acid ester representing 14 alkyl groups. When the above fatty acid ester is blended in the solvent in the above ratio, the dissolving power for the resin for varnish becomes more appropriate, and the effect of improving the gloss of the printed matter is exhibited without impairing the printability of the ink. .

  As the fatty acid ester, a simple substance of fatty acid ester derived from vegetable oil or a mixture thereof is preferably used, but other synthetic esters can also be used. As said fatty acid ester, what was produced | generated by esterification of a fatty acid and alcohol can be used, for example. Examples of the fatty acids include palm oil, palm oil, palm kernel oil, khair oil, Japanese maple seed oil, rice seed oil, basket seed oil, guava seed oil, grapefruit seed oil, white rice seed oil, white Fatty acids derived from vegetable oils and fats such as moji seed oil, peanut seed oil, potato seed oil and habiwa seed oil can be used. Since these plant-derived fatty acids are generally a mixture of a plurality of fatty acids, they can be separated and purified by a known method, and one or a mixture of two or more can be used. These plant-derived fatty acids may be produced by hydrolyzing vegetable oil, but commercially available products may also be used.

  As the fatty acid, a fatty acid representing an alkyl group or alkenyl group having 3 to 11 carbon atoms of R1 represented by the general formula (1) is used. Examples of the fatty acid include butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, undecylenic acid, and the like.

  Examples of alcohols that react with the fatty acid to produce the fatty acid ester represented by the general formula (1) include amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, Decyl alcohol, dodecyl alcohol, tridecyl alcohol, tetradecyl alcohol and the like, preferably 3-methyl-1-butyl alcohol, 2-ethyl-1-butyl alcohol, 2,4-dimethyl-3-pentyl alcohol having a branched chain, 2-ethyl-1-hexyl alcohol, 3,5,5-trimethyl-1-hexyl alcohol, 4-decyl alcohol, 2-isopropyl-5-methyl-1-hexyl alcohol, 2-butyl-1-octyl alcohol, etc. Linear and branched Alcohols having, and mixtures thereof. Commercially available products can be used for these alcohols.

  Examples of the method for producing the fatty acid ester include a method by a direct esterification reaction by a reaction between the fatty acid and an alcohol, and a transesterification reaction synthesized from an ester and an alcohol or an ester and a fatty acid, or an ester and an ester. Examples of the method include a method by a direct esterification reaction, such as a method, a method by reaction of acyl chloride and alcohol, and a method by reaction of epoxide and fatty acid. In the method based on the above direct esterification reaction, the fatty acid and the alcohol are mixed, and an appropriate azeotropic dehydrating agent such as toluene or xylene is added and heated, so that the reaction proceeds while distilling water. As the catalyst, Bronsted acid such as sulfuric acid and p-toluenesulfonic acid, Lewis acid such as zinc oxide, activated alumina, titanium oxide, and tetraisopropyl titanate are used.

  Examples of the fatty acid esters include fatty acid esters such as amyl, hexyl, heptyl, octyl, and decyl of butyric acid; fatty acid esters such as hexyl, heptyl, and octyl of valeric acid; amyl, hexyl, heptyl, octyl, and nonyl of caproic acid. , Decyl, undecyl, todecyl, tridecyl, tetradecyl, etc .; fatty acid esters such as amyl, hexyl, heptyl, octyl, etc .; fatty acid esters such as amyl, hexyl, heptyl, octyl, etc .; amyl of pelargonic acid, Fatty acid esters such as heptyl; fatty acid esters such as heptyl of capric acid.

  The fatty acid ester dramatically improves the solubility of the solvent in the varnish resin. In particular, among the fatty acid esters, fatty acid esters having a total carbon number X of 9 ≦ X ≦ 20, preferably 9 ≦ X ≦ 17 are preferably used. The fatty acid ester having the total carbon number is more effective in improving the gloss of the ink coating film, and has a boiling point with less influence on the evaporation and drying properties and on-machine stability of the ink. .

  Specific examples of the fatty acid ester include caproic acid octyl ester, caproic acid nonyl ester, caprylic acid hexyl ester, capric acid hexyl ester, lauric acid octyl ester, and a mixture thereof.

  The ink of the present invention can be used as a fatty acid ester alone or a mixture of several fatty acid esters as the solvent, but the content of the fatty acid ester is from 0.1 to the total solvent in the ink. It is less than 30% by mass, preferably 1 to 25% by mass. Here, the total solvent in the ink means all the solvents contained in the ink. For example, when the solvent is used at the time of varnish preparation and ink preparation, the solvent used for preparing the varnish, the ink This refers to a combination of solvents used during preparation. When the content of the fatty acid ester is within the above range, the effect of improving gloss can be obtained very efficiently. In addition, even if content of said fatty acid ester exceeds the said upper limit, the obtained ink cannot obtain the further significant gloss improvement effect.

  Moreover, the solvent used for this invention may mix another solvent, Preferably a petroleum-type solvent in the mixture ratio of said fatty acid ester. In addition, content of the solvent in the ink of this invention becomes like this. Preferably it is 30-60 mass%, More preferably, it is 35-55 mass%, Most preferably, it is 40-50 mass%.

  Examples of the petroleum solvent include a simple substance of a hydrocarbon solvent made of a paraffinic hydrocarbon, a naphthene hydrocarbon, a hydrocarbon having an aromatic content of 1% or less obtained from a petroleum fraction, or a mixture thereof. The above-mentioned petroleum-based solvents are “No. O Solvent (H)”, “AF Solvent No. 4”, “AF Solvent No. 5”, “AF Solvent No. 6”, “AF Solvent No. 7” from Nippon Oil Corporation. Can be used in the present invention alone or in combination.

  When the above petroleum solvent is used as a mixed solvent with the fatty acid ester, the mixing amount of the petroleum solvent is not particularly limited as long as the fatty acid ester is within the above range of all the solvents in the ink. . As the blending ratio of the petroleum solvent decreases, the effect of reducing the environmental load is exhibited.

  Examples of varnish resins used in the present invention include rosin ester resins, rosin-modified phenol resins, maleic acid-modified rosin ester resins, alkyd resins, rosin-modified alkyd resins, gilsonite resins, petroleum resins, hydrocarbon resins, acid-modified hydrocarbon resins. For example, rosin-modified phenolic resin and / or rosin ester resin are preferable.

  Examples of the rosin-modified phenolic resin include resins obtained by esterifying an addition product of rosin and a resole condensate with a polyol. The rosin modified phenolic resin has a weight average molecular weight of 10,000 to 300,000, preferably 30,000 to 200,000. When the weight average molecular weight of the rosin-modified phenol resin is within the above range, the fluidity and viscoelasticity of the ink obtained are more excellent.

  Examples of the rosin ester resin include those having a softening point of 120 to 210 ° C, preferably 140 to 200 ° C, and a weight average molecular weight of 20,000 to 300,000, preferably 50,000 to 200,000. Examples thereof include modified rosin ester resins obtained by esterification with a polyol by introducing rosin or diene compound into the rosin ester resin and adding a polybasic acid and / or unsaturated monocarboxylic acid. When the softening point and the weight average molecular weight of the rosin ester resin are within the above ranges, the fluidity and viscoelasticity of the resulting ink are more excellent.

  The ink varnish used in the ink of the present invention is prepared by blending the varnish resin, the fatty acid ester and other solvent, and if necessary, blending vegetable oil and a gelling agent. As a preparation method thereof, for example, the above varnish resin, the above fatty acid ester and petroleum solvent, and vegetable oil are blended, and heated and stirred uniformly at 200 ° C. for 30 minutes in a nitrogen stream, and then 150 Cool to 0 ° C., mix with a gelling agent, and further heat and stir at 200 ° C. for 60 minutes to prepare a varnish.

  As the above vegetable oil, known oils can be used, for example, non-drying oil such as castor oil, peanut oil, olive oil, semi-drying oil such as soybean oil, cottonseed oil, rapeseed oil, sesame oil, corn oil, and linseed Oils, eno oils, dry oils such as drill oil and the like, preferably semi-dry oils and / or dry oils. Of these, soybean oil and linseed oil are particularly preferred.

  As the gelling agent, known ones can be used, such as aluminum ethyl acetate diisopropylate, aluminum isopropylate, aluminum stearate, ethyl acetoacetate aluminum diisopropylate, aluminum diisopropoxysite. , Ethyl acetoacetate aluminum diisopropoxide, and the like, and mixtures thereof. Ethyl acetoacetate aluminum diisopropoxide is preferably used, and this is obtained from Kawaken Fine Chemical Co., Ltd. under the trade name ALCH. Can be used in the invention.

  The ink of the present invention may be of an overprint varnish type that does not contain a colorant in the ink varnish, but may be of a type containing a colorant. If necessary, additives such as paraffin wax, polyethylene wax, polytetrafluoroethylene wax, and other antifriction agents and plasticizers are uniformly kneaded and blended so long as they do not interfere with the object of the present invention.

  Examples of the colorant include inorganic pigments such as titanium oxide, barium sulfate, calcium carbonate, zinc white, and magnetic iron oxide, lake pigments, azo pigments, isoindoline pigments, phthalocyanine pigments, quinacridone pigments, anthraquinones. Conventional pigments such as organic pigments such as pigments, carbon black and dyes can be used.

  Next, the present invention will be described with reference to preparation examples of ink varnishes E1 to E6 used in this example and preparation examples of ink varnishes F1 to F4 used in comparative examples, and examples and comparative examples of inks using these varnishes. This will be described more specifically. “Part” or “%” in the text is based on mass unless otherwise specified. In addition, this invention is not limited to the following Example.

(Varnish E1-E6)
As shown in Table 1, rosin-modified phenol resin A or rosin ester resin B as a resin for varnish, which is a component of each varnish, soybean oil, fatty acid ester a as a solvent, and petroleum solvent b are blended. Then, heat and stir uniformly at 200 ° C. for 30 minutes in a nitrogen stream atmosphere, then cool to 150 ° C., and then mix with a gelling agent (ALCH), and then heat and stir uniformly at 200 ° C. for 60 minutes. Varnishes E1 to E6 were prepared.

(Preparation of varnish F1)
In the preparation of varnish E1, as shown in Table 1, varnish F1 was prepared in the same manner as in the preparation of varnish E1, except that only petroleum solvent b was used as the solvent.

(Preparation of varnish F2)
In the preparation of varnish F1, as shown in Table 1, the varnish was prepared in the same manner as in the preparation of varnish F1, except that rosin-modified phenolic resin A was 40 parts, soybean oil was increased, and petroleum solvent b was 44 parts. F2 was prepared.

(Preparation of varnish F3)
In the preparation of varnish F1, as shown in Table 1, the procedure was the same as the preparation of varnish F1, except that rosin-modified phenolic resin A was 34 parts, petroleum resin C was further added, and petroleum solvent b was 45 parts. Varnish F3 was prepared.

(Preparation of varnish F4)
In the preparation of varnish F1, as shown in Table 1, it is the same as the preparation of varnish F1, except that 44 parts of rosin-modified phenol resin A, 35 parts of petroleum solvent b, and 10 parts of fatty acid ester a5 are added. Thus, varnish F4 was prepared.

  In Tables 1 and 2, rosin-modified phenol resin A, rosin ester resin B, petroleum resin C, fatty acid ester a and petroleum solvent b as solvents are as follows.

[Resin for varnish]
Rosin-modified phenolic resin A: A rosin-modified phenolic resin having an acid value of 20 mgKOH / g and a weight average molecular weight of 80,000 manufactured by Arakawa Chemical Industries, Ltd.
・ Rosin ester resin B
The following production examples are used. To a reactor equipped with a stirrer and a thermometer, 800 g of rosin and 200 g of 1,3-pentadiene petroleum resin were added, heated to 200 ° C., and 80 g of acrylic acid and 20 g of maleic anhydride were added to synthesize a diene. . To the reaction product, 130 g of pentaerythritol and 0.5 g of magnesium oxide as a catalyst were added and subjected to an esterification reaction at 280 ° C. for 9 hours until the acid value became 15 mg KOH / g to give a rosin ester having a weight average molecular weight of 100,000. Resin B was obtained.
Petroleum resin C: Nippon Petrochemical Co., Ltd., Nisseki Neopolymer 120
[solvent]
・ Fatty acid ester a
a1: caprylic acid hexyl ester (total carbon number 14), a2: caproic acid nonyl ester (total carbon number 15), a3: capric acid hexyl ester (total carbon number 16), a4: lauric acid octyl ester (total carbon number 20) ), A5: lauric acid hexadecyl ester (total carbon number 28)
・ Petroleum solvent b: Shin Nippon Oil Co., Ltd., AF solvent 7

上記の表１の数値は部数を表わす。

The numerical values in Table 1 above represent the number of copies.

[Examples 1 to 6 and Comparative Examples 1 to 4]
Using the above varnishes E1 to E6 and varnishes F1 to F4, phthalocyanine blue was blended into each varnish as shown in Table 2, and kneaded uniformly by a known method, and then polytetrafluoroethylene wax was added. After that, the solvent used for the preparation of each of the above varnishes and the varnish were additionally blended so that the tack of the ink would be 10 to 11, and kneaded uniformly by a known method. Inks G1 to G6 of Examples and Inks H1 to H4 of Comparative Examples were prepared. The ink of Comparative Example 1 is a standard web offset printing ink having a standard composition. The above 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, and measuring the value after 1 minute. is there.

上記表２の数値は、脂肪酸エステルの含有率以外は部数を表わす。

The numerical values in Table 2 above represent the number of parts other than the content of fatty acid ester.

Each ink obtained above was evaluated with respect to gloss and printability by the following measurement methods. A comprehensive evaluation was also performed. The evaluation results are shown in Table 3. (Glossy)
Using 0.125 ml of each of the inks described above, the color is applied to the top coat paper with a RI tester 2-split roll manufactured by Ishikawajima Sangyo Co., Ltd. to produce a printed sample piece. Next, this sample piece is heated in an oven dryer at 150 ° C. for 20 seconds, and then left to stand for 6 hours or longer to dry and solidify the ink coating film. The gloss of the printed sample piece was measured using a digital gloss meter (incident / reflection angle = 60 ° / 60 °) manufactured by Murakami Color Research Laboratory.

(Printability)
Using each of the inks described above, printing was performed with a normal offset rotary printing press, and the dryness and image reproducibility were determined according to the following criteria.
◯: No rubbing or poor printing condition is recognized on the printing surface, and printing reproducibility comparable to the printed document can be obtained stably.
X: Rubbing or poor printing is recognized on the printing surface, and there is no reproducibility of printing comparable to a printed document.

(Comprehensive evaluation)
From the above evaluation results of gloss and printability, each ink was evaluated by the following evaluation method to determine whether a highly glossy print can be obtained without impairing physical properties such as printability of the ink.
◯: A printed matter in which the gloss of the ink coating on the surface of the printing paper is greatly improved can be obtained without impairing the physical properties of printability.
Δ: In practical use, the physical properties of printability are not impaired, but the gloss of the ink coating on the printing paper surface is slightly inferior.
X: Printability is inferior and out of the practical range.

  From the above evaluation results, the ink of the present invention was printed significantly without impairing physical properties such as printability, in particular, compared to the conventionally used offset rotary printing ink of the standard composition of Comparative Example 1. It has been demonstrated that printed matter with improved gloss of the ink coating on the paper can be obtained. In addition, the inks of Comparative Examples 2 and 3 using conventional formulations and Comparative Example 4 using a fatty acid ester outside the compatible range all had poor printability and could not obtain a high-quality printed matter.

According to the present invention, the ink of the present invention can obtain a high-quality printed matter having high gloss without impairing physical properties such as printability, and has an environmental load with reduced use of petroleum solvents. It can be used effectively as a small amount of offset rotary printing ink.

Claims (7)

An offset rotary printing ink comprising a resin for a varnish and a solvent, the fatty acid ester represented by the following general formula (1) being contained in the solvent in an amount of less than 0.1 to 30% by mass.
R1COOR2 (1)
(In the general formula (1), R1 represents an alkyl group or alkenyl group having 3 to 11 carbon atoms, and R2 represents an alkyl group having 5 to 14 carbon atoms.)   The ink according to claim 1, wherein a total carbon number X of the fatty acid ester is 9 ≦ X ≦ 20.   The ink according to claim 1 or 2, further comprising a petroleum solvent as a solvent in addition to the fatty acid ester.   The ink according to claim 1, wherein the varnish resin is a rosin-modified phenol resin and / or a rosin ester resin.   Furthermore, the ink of any one of Claims 1-4 containing a coloring agent. A gloss improver for offset rotary printing ink, represented by the following general formula (1):
R1COOR2 (1)
(In the general formula (1), R1 represents an alkyl group or alkenyl group having 3 to 11 carbon atoms, and R2 represents an alkyl group having 5 to 14 carbon atoms.) The gloss improver according to claim 6, wherein the total number X of carbon atoms of the fatty acid ester is 9 ≦ X ≦ 20.