JP2003012987A - Printing ink - Google Patents

Abstract

(57) [Problem] To provide a printing ink capable of minimizing shrinkage of a rubber roll and a blanket of a printing press from an ink level while maintaining a balance between on-press stability and drying performance in conventional printing. In a printing ink containing a pigment, a resin for varnish, and a solvent, the solvent is a fatty acid ester obtained by transesterifying a fat or oil with a monohydric or dihydric alcohol in an amount of 5 to 50% by weight in the total ink. Vegetable oil in all inks
60% by weight and non-aromatic petroleum solvent in all inks
A printing ink comprising 40% by weight.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing ink, and more specifically, it is possible to shrink a rubber roll and a blanket of a printing machine even if the printing ink is a combination of a non-aromatic petroleum solvent and a vegetable oil, which causes less pollution of the global environment and working environment. The present invention relates to a penetration drying type printing ink capable of suppressing (thinness / thinness) as much as possible.

[0002]

2. Description of the Related Art In recent years, as a solvent used for an offset printing ink, an aromatic hydrocarbon contained therein is mainly converted to a non-aromatic component by hydrogenation. In particular, it has been pointed out that the solvent containing a polycyclic aromatic hydrocarbon having three or more rings has a problem in environmental hygiene.

Infiltration-drying type printing ink is required to suppress the evaporation of the solvent on the printing machine in order to maintain the stability of the ink during high-speed printing, and it is essential to use a solvent having a high boiling point. It was For this reason, conventional solvents were mainly used as high-boiling fractions during petroleum refining, but these solvents have a high aromatic component content, and in recent years, mainly non-aromatic components have been environmentally friendly. Substitution with solvent is progressing, and it is being used by various printing manufacturers as an environmentally friendly ink. Solvents mainly composed of non-aromatic components are conventional aromatic solvents (hereinafter,
Solubility with resin becomes a problem compared with mineral oil).
In particular, in the case of a high-boiling point non-aromatic solvent, when formed into an ink, the solubility of the resin is poor, so that the fluidity is deteriorated, and problems such as poor transfer occur. As a supplement to the solubility of the resin, vegetable oil containing a fatty acid ester as a main component has good resin solubility and a small amount of volatile components.

In the lithographic printing ink of the oxidative polymerization type drying method, vegetable oil containing unsaturated fatty acid ester called a drying oil as a main component is used, and after printing, a film is formed by acid value polymerization of the unsaturated portion in the fatty acid. Forming and fixing the ink. However, if the content of vegetable oil is increased, the solvent is less likely to be released due to excessive resin solubility, and the surface dryness immediately after printing (hereinafter referred to as a set) is deteriorated. In addition, since the ratio of unsaturated components in the ink becomes high, the ink itself tends to form a dry film on the surface, and the workability also deteriorates.

In the lithographic printing ink which adopts the permeation drying type drying system, increasing the content of the drying oil contributes to the improvement of the on-machine stability, but deteriorates the set due to the delay of the solvent removal from the resin. Is the same as the oxidation polymerization type ink. On-press stability refers to the degree of deterioration of fluidity due to solvent evaporation of ink on a printing press. Ink performance is excellent in that there is little deterioration in fluidity, or that it takes a long time to deteriorate fluidity.

[0006]

[Problems to be Solved by the Invention]
A solvent containing almost no tricyclic or more polycyclic aromatic hydrocarbons (1% or less), which has some problems in terms of environmental hygiene, for printing workers and readers who see printed matter. Therefore, each printing maker is promoting the replacement of this environmentally friendly ink with a safe and environmentally friendly printing ink, which contributes to global environmental conservation.

However, among the ink components used in these environmentally friendly inks, non-aromatic petroleum solvents and vegetable oils tend to shrink rubber rolls and blankets of printing machines. If the rubber roll and the blanket of the printing machine are contracted, the nip width between the rolls is narrowed, improper inking and the like occur, and a good printing paper surface cannot be obtained.

The mechanism relating to the contraction of the rubber roll and blanket is that the non-aromatic petroleum solvent and vegetable oil contained in the eco-friendly ink cause the voids to be generated by extracting the plasticizer in the rubber. Due to contraction.
Similarly with conventional mineral oil, the plasticizer in the rubber is extracted to form voids, but since the aromatic solvent has an affinity with rubber, it has the effect of refilling (swelling) the voids and shrinking. Relieve

[0009] Therefore, each ink company has studied to suppress the contraction of the rubber roll and the blanket from the ink surface as much as possible, but no sufficient solution has been found yet. on the other hand,
Even rubber manufacturers have been making improvements to rubber rolls and blankets for environmentally friendly inks, but they are not yet complete.

[0010]

DISCLOSURE OF THE INVENTION An object of the present invention is to perform printing capable of suppressing the shrinkage of a rubber roll and a blanket of a printing machine from the ink side as much as possible while maintaining the balance between the on-press stability and the drying property in the conventional printing. It is to provide ink.

Another object of the present invention is to provide a method for suppressing the shrinkage of a rubber roll and a blanket of a printing machine when a printing ink containing a non-aromatic solvent is used.

[0012]

That is, the present invention provides a printing ink containing a pigment, a varnish resin, and a solvent.
The above solvent is a fatty acid ester obtained by transesterifying fats and oils with a monohydric or dihydric alcohol in 5 to 5% of all inks.
The present invention relates to a printing ink containing 50% by weight, 10 to 60% by weight of vegetable oil in all inks and 10 to 40% by weight of non-aromatic petroleum solvent in all inks.

The present invention further includes a pigment, a varnish resin, and
A permeation-drying ink comprising a non-aromatic petroleum solvent and a solvent containing vegetable oil, and a fatty acid ester obtained by transesterifying fats and oils with a monovalent or divalent alcohol are added. The present invention relates to a method for suppressing contraction of rubber rolls and blankets.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Examples of fats and oils used as a raw material for the fatty acid ester used in the present invention include soybean oil, linseed oil, corn oil, rice bran oil, rapeseed oil, dehydrated castor oil, wheat germ oil, sesame oil, tall. Examples thereof include oils, hemp oil, eno oil, sunflower oil, tung oil, cinnamon oil, safflower oil, cottonseed oil, and other vegetable oils, swordfish oil, fish oils such as sardine oil, mackerel oil, squid oil, and natural oils and fats such as whale oil.

The monohydric or dihydric alcohol used for transesterifying the above-mentioned fats and oils is, for example,
Saturated alcohols such as methanol, ethanol, n- or iso-propanol, n, sec or tet-butanol, heptinol, 2-ethylhexanol, hexanol, octanol, decanol, dodecanol, etc.
Oleyl alcohol, dodecenol, fuseteri alcohol, sommaryl alcohol, gadreyl alcohol,
Unsaturated aliphatic alcohols such as 11-icosenol, 11-docosenol, and 15-tetracosenol can be mentioned.

Examples of the reaction for transesterifying the above-mentioned fats and oils with the above-mentioned alcohol include a method in which both are heated under normal pressure or under pressure in the absence of a catalyst, preferably an acid catalyst or an alkali catalyst. May be The transesterification reaction product can be used as it is,
The transesterified product may be used by fractionating the ester of a fatty acid by distillation. Such a transesterified product is used in a proportion of 5% by weight to 50% by weight, preferably 10% by weight to 30% by weight in the printing ink of the present invention. If it is 5% by weight or less, it is impossible to suppress the contraction of the rubber roll and the blanket of the printing machine, and if it is 50% by weight or more, the rubber roll and the blanket swell.
It causes a problem when printing.

The vegetable oil used as the solvent in the present invention is preferably a drying oil such as linseed oil, tung oil, eno oil, etc. or a semi-drying oil such as soybean oil, rice bran oil, rapeseed oil, sesame oil, etc. It is also possible to use a non-drying oil such as olive oil or palm oil together. The amount of addition is 10% by weight to 60
Weight percent is preferred. If it is 10% by weight or less, the fluidity of the ink is insufficient due to insufficient solubility with the resin. Further, in some cases, there is a problem in on-board stability. Further, if it is 60% by weight or more, the set deteriorates.

The non-aromatic petroleum solvent used in the present invention is
For example, it contains naphthene having 14 to 18 carbon atoms and isoparaffin as main components. Aniline point is 65-110 ° C
Is preferred. If a solvent having an aniline point higher than 110 ° C. is used, the solubility in the resin used in the ink composition is poor, the fluidity of the ink is insufficient, and as a result, the leveling on the printing medium is poor and there is no gloss. Only prints are available. Further, an ink using a solvent having an aniline point lower than 65 ° C. has a poor removability of the solvent from the ink film during drying and causes deterioration in drying. As such a non-aromatic petroleum solvent, there are Nos. 0 and AF4 to 7 solvents manufactured by Nisseki Mitsubishi Corp.

As other auxiliaries used in the present invention, additives such as a drier, a gelling agent, a drying inhibitor (delaying agent) and an antioxidant can be appropriately used.

The varnish resin used in the present invention includes:
A rosin-modified phenolic resin is preferable, and a petroleum resin and an alkyd resin can be used in combination if necessary. The weight average molecular weight of the rosin-modified phenol resin is 10,000 to
400,000 is desirable. If it is less than 10,000, the viscoelasticity of the ink is insufficient, and if it is more than 400,000, the fluidity of the ink is insufficient. As the solubility of the rosin-modified phenolic resin, one having a tolerance of 10% to 40% in No. 0 solvent solvent manufactured by Nippon Oil Co., Ltd. is desirable. If it is less than 10%, the ink setting deteriorates, and if it exceeds 40%, the fluidity of the ink decreases.

What is tolerance? Take resin Xg in a test tube,
It is the minimum resin concentration at which white turbidity does not occur when it is heated to dissolve in a solvent and then cooled to 25 ° C. The smaller the value, the better the solubility.

Tolerance (%) = resin (Xg) / [resin (Xg) + solvent (Yg)] × 100 The pigments used in the present invention are those used in conventional printing inks, Any known pigment can be used as it is as the pigment for the printing ink of the present invention. The amount of the ink used may be the same as that of a conventionally known printing ink, and for example, a ratio of about 10 parts by weight to 40 parts by weight in 100 parts by weight of the printing ink is general.

[0023]

EXAMPLES Next, the present invention will be explained based on examples.
In the examples, "part" and "%" are "part by weight" and "% by weight", respectively.
Is.

[Example of varnish production] (Production of rosin-modified phenol resin gel varnish 1) A rosin-modified phenol resin (Arakawa Chemical Industry Co., Ltd.) was placed in a four-necked flask equipped with a condenser, a thermometer, and a stirrer.
Made, weight average molecular weight 220,000, acid value 20, softening point 162
) 38.5 parts, soybean oil 30 parts, No. 6 solvent (manufactured by Mitsubishi Nisseki Co., Ltd.) 30 parts, heated to 180 ° C., stirred at the same temperature for 30 minutes, then allowed to cool, and gel 1.0 part of ethyl acetoacetate aluminum diisopropoxide (ALCH manufactured by Kawaken Fine Chemical Co., Ltd.) was charged as an agent and stirred at 180 ° C. for 30 minutes to obtain a rosin-modified phenol resin gel varnish 1. No. 6 solvent is a conventional aromatic petroleum solvent and is said to be partially harmful.
It contains polycyclic aromatic hydrocarbons with three or more rings.

(Production of rosin-modified phenol resin gel varnish 2) A rosin-modified phenol resin (manufactured by Arakawa Chemical Industry Co., Ltd., weight average molecular weight 220,000, acid value 20) was placed in a four-necked flask equipped with a condenser, a thermometer and a stirrer. , Softening point 162 ° C.) 38.5 parts, soybean oil 30 parts, AF Solvent No. 6 (hereinafter referred to as AF6) (manufactured by Mitsubishi Nisseki Co., Ltd.) 30
Parts, heated to 180 ° C., stirred at the same temperature for 30 minutes and then allowed to cool, 1.0 part ethylacetoacetate aluminum diisopropoxide as gelling agent (ALCH manufactured by Kawaken Fine Chemicals Co., Ltd.) Charge 3 at 180 ° C
Stir for 0 minutes and rosin-modified phenolic resin gel varnish 2
Got

[Examples of ink production] Examples 1 to 4 and Comparative Examples 5 to 8 60 parts of rosin-modified phenol resin varnish 1 and 17 parts of indigo pigment (Rionol Blue FG-7330, manufactured by Toyo Ink Mfg. Co., Ltd.) The ingredients were blended and kneaded with a triple roll to obtain indigo ink base 1.

Subsequently, rosin-modified phenol resin varnish 2
60 parts of indigo pigment (Lionol Blue FG-7330,
17 parts of Toyo Ink Mfg. Co., Ltd. was mixed and kneaded with a triple roll to obtain indigo ink base 2.

Next, a solvent was added to the indigo ink bases 1 and 2 in the composition shown in Table 1 to obtain a viscosity of 5.0 to 5.5P.
The printing ink compositions of Examples 1 to 4 and Comparative Examples 5 to 8 were obtained by adjusting to a · s.

Evaluation Results The printing ink compositions of the above Examples and Comparative Examples were evaluated for on-machine stability, shrinkage of the rubber roll and blanket of the set and printing machine, and the results are shown in Table 2.

The on-machine stability was measured with a digital incometer manufactured by Toyo Seiki Co., Ltd. at 40 ° C., ink 0.1 cc, 100
The evaluation was performed by the difference between the maximum value and the initial value of the tack value under the condition of 0 rpm (hereinafter referred to as ΔT value) and the elapsed time until the maximum value was displayed (hereinafter referred to as Tmax value). The smaller the ΔT value and the larger the Tmax value, the less the fluctuation of the tack value of the ink and the more excellent the ink performance.

The set is made of newspaper newspaper and has a density of 1.00.
Immediately after the color is developed, apply the coated paper to the surface to be developed immediately after the color development, apply a pressure of 10 bar while gradually shifting it, and observe the transfer of ink from the new paper to the coated paper. The evaluation was carried out according to the time.
The shorter the set time is, the better the set is. However, if the set time is too short, the guide roller may become dirty in actual printing.

The shrinkage of the rubber roll and blanket of the printing machine was evaluated by the following rubber immersion test. Rubber sheet A (manufactured by Kinyosha Co., Ltd .; hardness 30) and B (manufactured by Meiwa Rubber Industry Co., Ltd., hardness 25) were 100 mm × 15 mm × 2.
Cut into 2 mm to make a pair. Before dipping these rubber sheets, the weight, volume and hardness are measured. 100 g of ink is put in a fixed quantity container, and a rubber sheet is immersed. Take out after soaking for 40 days, and wipe off the ink adhering to the rubber sheet well with a cloth etc. without using a solvent. After standing for 1 hour, the weight, volume and hardness are measured. The ratio of the change after the immersion to the weight, volume, and hardness measured before the immersion is expressed as a percentage by the weight change rate, the volume change rate, and the hardness change rate. When the plasticizer in the rubber is extracted, the weight and volume decrease, and the weight change rate and the volume change rate become negative. Also, the hardness becomes hard and the rate of change in hardness becomes positive.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

INDUSTRIAL APPLICABILITY As described above, the ink obtained according to the present invention can improve the on-machine stability and the setting as compared with the conventional environment-friendly ink, and at the same time, the rubber expansion and contraction which is a problem. It was also greatly suppressed. Therefore, according to the present invention, even in the conventional environment-friendly ink, the degree of expansion and contraction of rubber is suppressed to the same level as that of the mineral oil-type ink containing the polycyclic aromatic component of Comparative Example 8, which is partially harmful. It was possible to provide an ink composition that can be made to do so.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4J039 AB03 AB04 AB06 BC02 BC20                       BE01 BE12 CA07 EA12 EA48                       GA02

Claims (3)

[Claims] 1. A printing ink containing a pigment, a varnish resin and a solvent, wherein the solvent comprises 5 to 50% by weight of a fatty acid ester obtained by transesterifying fats and oils with a monohydric or dihydric alcohol. , Vegetable oil 10 in all inks
-60% by weight and 10% non-aromatic petroleum solvent in all inks
A printing ink containing about 40% by weight. 2. The printing ink according to claim 1, wherein the printing ink is a penetration drying type ink. 3. A permeation-drying ink comprising a pigment, a varnish resin, and a solvent containing a non-aromatic petroleum solvent and a vegetable oil, which is obtained by transesterifying fats and oils with a monovalent or divalent alcohol. A method for suppressing shrinkage of a rubber roll and a blanket of a printing press, which comprises adding a fatty acid ester.