JP5700153B1 - Heatset offset ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink for lithographic printing which can improve printing quality and printing workability, and is excellent in friction resistance, gloss and fleshing property, can reduce piling, and can contribute to reduction of environmental load. A rice wax having a crystal melting point peak measured by a differential scanning calorimeter at 76 to 85 ° C. and a half width of 8 ° C. or less is 0.5 to 2% by weight, pigment, binder resin and petroleum solvent. And a lithographic printing ink composition comprising vegetable oils. [Selection figure] None

Description

The present invention relates to a heatset type lithographic printing ink composition (hereinafter abbreviated as “ink”) used for lithographic printing for printing books, leaflets, catalogs, posters, and the like, and in particular, improved printing quality. Further, the present invention relates to an ink that is excellent in friction resistance, gloss, and inking properties, and that can reduce piling.

In recent years, heatset lithographic printing has increased in printing speed for the purpose of improving productivity, and printing paper has been diversified, such as increased reuse of used paper and increased import paper. Reduction is required.

In offset printing, ink is supplied from an ink fountain via a plurality of rollers to a printing plate, transferred from the printing plate to a sheet via a blanket, and an image is reproduced. In the case of web offset printing, when it passes through a dryer, it receives hot air of about 180-230 ° C and evaporates, and then it is dried, passed through a guide roller, turn bar, triangular plate, etc., and folded and bound by a folding machine. In general, the paper surface may be rubbed while passing through a plurality of rollers after passing through the dryer. In particular, in recent years, as the utilization rate of recycled paper is improved, the number of papers with weak paper surface strength is increasing, and there is a situation where rubbing is more likely to occur than before. As a measure for reducing rubbing, it is common to mix an appropriate amount of wax in the ink. Wax having a particle diameter exceeding the thickness of the ink film on the paper surface has the effect of reducing rubbing.

As a method for solving such a problem of friction resistance, Patent Document 1 provides a friction resistance after printing on a printing press by adding a plurality of types of waxes such as a melt-type wax and a dispersion-type wax. Yes. One of them, microcrystalline, suppresses adhesion to the cooling roller after passing through the dryer and remaining guide rolls.

Similarly, Patent Document 2 discloses the addition of wax using isoparaffin and / or cycloparaffin having a melting point of 70 to 85 ° C., but these have the effect of suppressing the adhesion of ink to the cooling roller and the remaining guide. It is shown.

Since such paraffinic hydrocarbon waxes are supplied at a very low cost, they are used not only in inks but also in various varieties. In order to take out the fraction to be obtained by an operation such as distillation, it is composed of components having a wide melting point, and unnecessary components are also contained.

Above all, as described above, the paraffin wax generally used in ink is obtained by separating crude oil from the oil distilled under reduced pressure and having 20 to 40 carbon atoms, a molecular weight of about 300 to 550, and about 90% of normal paraffin. ing. For this reason, the paraffin wax is a mixture and generally contains impurities having a carbon number of 5 to 10 in addition to a hydrocarbon compound having a main melting point of 36 carbon atoms. For this reason, paraffin wax refined from crude oil contains impurities and impurities, and contains many components that do not contribute to the effect of friction resistance. Adding more increases the risk of gloss reduction and piling on the blanket.

On the other hand, for the purpose of reducing environmental load, efforts are currently being made to use decalcified materials and reduce VOC components in printing inks. Considering transportation mileage, paraffinic hydrocarbons made from crude oil have a very large load from the viewpoint of reducing CO ₂ emissions.

In other words, from the viewpoint of transportation mileage, which reduces CO ₂ emissions by shortening the distance between the production / manufacturing site and the consumption area of raw materials and products, etc., the ink raw material is procured near the ink manufacturing area. It is preferable.

Patent Publication 2007-254629 Patent Publication 2003-221536

The present invention has been made in order to solve such problems in the prior art, and the subjects of the present invention are, in particular, improvement of printing quality and improvement of printing workability, friction resistance, glossiness. In addition, the present invention relates to an ink that has excellent inking properties and can reduce piling. Furthermore, it relates to ink that contributes to reducing the environmental burden from the viewpoint of CO ₂ emissions.

A lithographic printing ink composition containing a pigment, binder resin, wax, petroleum-based solvent and vegetable oil contains a certain amount of rice wax having a certain range of melting point, excels in friction resistance, gloss and inking properties, and is a pillar The present inventors have invented a heatset type lithographic printing ink composition characterized in that

That is, the present invention relates to a lithographic printing ink composition characterized by containing rice wax, a binder resin, and vegetable oils.

Furthermore, in the present invention, the rice wax has a crystal melting point peak at 780 to 80 ° C. when measured with a differential scanning calorimeter,
The lithographic printing ink composition according to claim 1, wherein the half width is 8 ° C. or less.

Furthermore, this invention relates to the said lithographic printing ink composition characterized by containing 0.5 to 2 weight% of rice waxes in the lithographic printing ink composition whole quantity.

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

Conventionally, it has been common to add molten hydrocarbon wax to reduce ink adhesion and guide residue on the printing machine's cooling roller under high-speed printing conditions. Crude oil used as a raw material has a large transportation mileage, which is very heavy on the environment.

According to the present invention, an ink suitable for high-speed printing that can improve the printing workability by improving the friction resistance of printed matter and reducing the occurrence of piling without impairing the gloss and the inking property is provided. Became possible. Furthermore, by using rice wax made from rice bran, it is possible to promote local production for local consumption, reduce transportation mileage, and reduce the environmental burden.

The binder resin used in the present invention is a rosin-modified phenol resin, rosin-modified maleic resin, alkyd resin, polyester resin, petroleum resin, or the like, which can be used alone or in combination of two or more, preferably It is desirable to use a rosin modified phenolic resin.

The weight average molecular weight of the rosin-modified phenol resin that is a binder resin is preferably in the range of 20000 to 200000, more preferably 25000 to 16000, and still more preferably in the range of 30000 to 120,000. If it is less than 20000, there is a concern that elasticity will be low and misting will increase, and if it exceeds 200,000, there is a concern that fluidity and inking properties will be deteriorated.

The rosin-modified phenolic resin relating to the present invention preferably has a normal paraffin turbidity temperature in the range of 40 to 160 ° C, more preferably in the range of 50 to 130 ° C. In the present invention, the normal paraffin white turbidity temperature refers to the lower limit temperature at which white turbidity occurs when 10% by weight of resin and 90% by weight of normal paraffin having 14 to 16 carbon atoms are heated and mixed. Is not observed.) If the temperature is lower than 40 ° C., the resin has too high solubility, and the tackiness of the ink becomes high. If the clouding temperature exceeds 160 ° C., the solubility of the resin is too low, so that the solvent is easily removed and the ink is easily tightened on the machine.

It refers to the wax and anti-friction agent in the present invention, and imparts the property of suppressing the rubbing of the printing surface by adding to the lithographic printing ink composition.

One of the waxes is a dispersion wax, such as polyethylene (PE), polytetrafluoroethylene (PTFE), and the like, which are fine particles having an average particle diameter of 1 to 10 μm, preferably 3 to 7 μm. The anti-friction agent is a printing surface in which a part of fine particles protrude from the printing surface and the contacted material comes into contact with the smooth surface to give the printing surface slipperiness, and the printing surface comes into direct contact with the contacted material. Prevent scratches. Therefore, the anti-friction resin fine particles are difficult to be deformed against an external pressure, and spherical or nearly spherical shapes are used. In addition, if the average particle size of the wax particles is 3 μm or less, particularly 1 μm or less, a sufficient anti-friction effect cannot be obtained, and if it is 7 μm or more, particularly 10 μm or more, the anti-piling property is insufficient, and the smoothness is low. Loss and gloss can be reduced.

Molten hydrocarbon waxes having a melting point of less than 100 ° C. such as microcrystalline are often used as surface coatings on the printing surface. When offset printing is performed by a sheet-fed printing method, the wax particles do not melt and adhere to the printing surface or exist as protruding from the printing surface. The average particle diameter of the wax particles is 0.1 to 100 μm, preferably 3 to 10 μm. When the wax particles come into contact with an object to be contacted, the wax particles melt by friction to provide slipperiness and protect the printing surface.

Hydrocarbon wax having a melting point of less than 100 ° C. such as microcrystalline is also used in a heat-set offset type off-wheel printing method with heat drying, and the wax that has been melted after passing through a dryer where the paper surface temperature reaches 100 ° C. or more. By covering the printing surface, it shows the effect of reducing ink cooling and remaining guide.

In the present invention, rice wax is an essential component. Rice wax is a substitute for hydrocarbon wax having a melting point of less than 100 ° C. Rice wax is also called rice bran wax and is a wax obtained when refining rice bran oil extracted from rice bran.

The main components of rice wax are esters of higher alcohols and higher fatty acids, and the fatty acids constituting the esters are mostly C22 behenic acid and C24 lignoceric acid, and the alcohol components are C24 to C36. It is characterized by being a hard wax with higher crystallinity than hydrocarbon waxes. Therefore, it is an essential structure in the present invention because it is superior in printability such as gloss and cooling compared to hydrocarbon wax containing a large amount of impurities.

The rice wax in the present invention is preferably 0.5 to 2% by weight based on the total ink composition, and if it is less than 0.5% by weight, the printed surface after passing through the dryer cannot be sufficiently covered, and cooling is removed or the guide remains. In some cases, the reduction of the occurrence of slag may not be sufficient, and if it exceeds 2% by weight, problems such as piling may occur.

In order for the rice wax according to the present invention to exert the maximum effect, heat-set type offset printing in which hot air drying is performed with a dryer is appropriate. When the paper surface temperature reaches 100 ° C. or higher when passing through the dryer, the wax component is melted, the surface is coated, and cooling and removal of the guide are suppressed.

The above-mentioned anti-friction agent including the rice wax of the present invention can be used as it is as a powder or a dispersion liquid, but it is also possible to use a compound that has been previously dispersed in an ink varnish or solvent and compounded. .

As a method of adding the anti-friction agent including the rice wax of the present invention, it can be added at any step in the conventional printing ink manufacturing process. In other words, the pigment and rice both dispersed in the varnish and kneaded may be converted into ink, or the dispersion and kneading process may be mixed with the anti-friction agent to form an ink. The latter is preferable for exhibiting the above. The same effect can be obtained by mixing wax with the printing ink that has become a product.

In addition, various additives for the purpose of anti-friction, anti-blocking, slip and scratch can be used as other additives in the lithographic printing ink composition. Leveling agents and surface active agents can be used as necessary. An agent, an antifoaming agent, or the like may be added, but it may be less than 6% of the total ink composition because there is a concern of inducing pyring.

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

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

The fatty acid monoester is a fatty acid monoester obtained by transesterification of the above vegetable oil and monoalcohol or a direct ester reaction between the fatty acid of the vegetable oil and monoalcohol. Representative examples of monoalcohol include methanol, ethanol, n- or iso-propanol, n, sec or tert-butanol, heptynol, 2-ethylhexanol, hexanol, octanol, decanol, dodecanol and other saturated alcohols, oleyl alcohol, Examples thereof include unsaturated aliphatic alcohols such as dodecenol, ficesteryl alcohol, somaryl alcohol, gadrelyl alcohol, 11-icosenol, 11-docosenol, and 15-tetracosenol.

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

Examples of the pigment used in the present invention include general inorganic pigments and organic pigments. Examples of inorganic pigments include yellow lead, zinc yellow, bitumen, barium sulfate, cadmium red, titanium oxide, zinc white, dial, alumina white, calcium carbonate, ultramarine, carbon black, graphite, and aluminum powder. Organic pigments include azo pigments, soluble azo pigments such as C-based (β-naphthol-based), 2B-based and 6B-based (β-oxynaphthoic), β-naphthol-based, β-oxynaphthoic acid anilide-based, monoazo yellow-based, disazo Insoluble azo pigments such as yellow and pyrazolone, condensed azo pigments such as acetoacetate allylide, phthalocyanine, copper phthalocyanine (α blue, β blue, ε blue), halogenated copper phthalocyanine such as chlorine and bromine, metal Examples of free phthalocyanine pigments and polycyclic pigments include perylene, perinone, quinacridone, thioindigo, dioxazine, isoindolinone, and quinophthalone pigments. The addition amount of the pigment is 5 to 30% by weight with respect to the total amount of the printing ink composition.
If no pigment is used, it can be used as a clear ink. Accordingly, the pigment is not an essential component in the present invention.

The petroleum solvent in the present invention is a petroleum solvent having an aromatic hydrocarbon content of 1% or less, an aniline point of 60 to 130 ° C., and a boiling point of 230 to 400 ° C., preferably an aniline point of 80 to 100 degreeC and a boiling point are 240-310 degreeC. The total amount of the lithographic printing ink preferably contains 0-30% petroleum solvent, more preferably 5-15%. When the aniline point of the petroleum solvent is 60 to 130 ° C., the ability to dissolve the resin is suitable, and it is preferable in terms of ink setting properties, glossiness, and inking. Examples of such non-aromatic petroleum solvents include AF Solvent No. 4, AF Solvent No. 5, AF Solvent No. 6, and AF Solvent No. 7 manufactured by JX Nippon Oil & Energy Corporation.

The lithographic printing ink composition of the present invention can be produced by a conventionally known method. As an example, a binder resin, petroleum-based solvent, vegetable oil, and a gelling agent as necessary are added, and varnish is produced under cooking conditions of 190 ° C. for 1 hour. Next, for example, a base for printing ink can be obtained by adding a pigment, petroleum solvent, vegetable oil, pigment dispersant or pigment dispersion resin to the varnish and dispersing with a bead mill or three rolls. Subsequently, petroleum-based solvents, vegetable oils, and other additives are added to adjust to a predetermined viscosity to obtain a printing ink composition. As the type of ink, ink for offset rotary printing press is the main one, but it is not limited to this.

As an example of the composition of the lithographic printing ink composition of the present invention,
・ Pigment 5-30% by weight
・ Binder resin 20-40% by weight
・ Petroleum solvent 20-45% by weight
・ 7 to 20% by weight of vegetable oil
・ Rice wax 0.5-2% by weight
・ 1-5% by weight of other additives
Etc. are mentioned as preferred compositions.
Examples of the substrate used in the present invention include general printing paper such as coated paper typified by coated paper and art paper, and non-coated paper typified by high-quality paper and low-quality paper.

The present invention will be described in more detail with reference to the following examples. However, the following examples do not limit the scope of rights of the present invention. In the present invention, “part” represents “part by weight” and “%” represents “% by weight” unless otherwise specified.

In the present invention, the weight average molecular weight was measured by gel permeation chromatography (HLC-8220) manufactured by Tosoh Corporation. A calibration curve was prepared with a standard polystyrene sample. Tetrahydrofuran was used as the eluent, and three TSKgel SuperHM-M (manufactured by Tosoh Corporation) were used as the column.

(Rosin modified phenolic resin production example)
In a reaction vessel, 1500 parts of gum rosin was reacted in advance with 100 parts of tertiary butylphenol, 500 parts of octylphenol and 210 parts of 92% by weight paraformaldehyde at 100 ° C. for 4 hours in a xylene solvent to remove water. A phenol resin was dropped at 150 ° C. and reacted for 2 hours. Furthermore, 160 parts of pentaerythritol was added and reacted at 250 ° C. for 12 hours using 1.5 parts of calcium oxide as a catalyst. By sequentially taking out in the course of the reaction, rosin-modified phenol resin A (weight average molecular weight 70000) was obtained.

(Manufacture of gel varnish for heat set offset printing ink)
44 parts by weight of resin A (weight average molecular weight 70000), 35 parts by weight of soybean oil, 20 parts by weight of AF Solvent No. 7 (manufactured by JX Nippon Oil & Energy Corporation) in a four-neck flask with a stirrer, Liebig condenser and thermometer Charged, heated to 190 ° C., stirred at the same temperature for 30 minutes, allowed to cool, and 1 part by weight of ethyl acetoacetate aluminum diisopropoxide as gelling agent (ALCH manufactured by Kawaken Fine Chemical Co., Ltd., hereinafter referred to as ALCH) Was stirred at 190 ° C. for 30 minutes to obtain a gel varnish for heat-set type offset printing ink (hereinafter referred to as “gel varnish”).

(Rice wax compound production example)
Rice wax SS-I purchased in a 4-neck flask with a stirrer, Liebig condenser and thermometer
100 parts by weight of flakes and 300 parts by weight of regenerated soybean oil (iodine number 117) were charged, heated to 100 ° C., stirred at the same temperature for 30 minutes, and then naturally cooled with stirring to obtain wax compound A. .

(Rice wax compound production example)
Rice wax SS-II (made by Borso oil) purchased in a 4-neck flask with a stirrer, Liebig condenser and thermometer
100 parts by weight of flakes and 300 parts by weight of regenerated soybean oil (iodine number 117) were charged, heated to 100 ° C., stirred at the same temperature for 30 minutes, and then naturally cooled with stirring to obtain wax compound B. .

(Production example of stearyl stearate wax compound)
A stirrer, a Liebig condenser, and a 4-neck flask with a thermometer were charged with 100 parts by weight of white beads of stearyl stearate, a higher fatty acid ester, and 300 parts by weight of regenerated soybean oil (iodine number 117), and the temperature was raised to 100 ° C. After stirring for 30 minutes at the same temperature, natural cooling was performed while stirring to obtain wax compound C.

(Paraffin wax compound production example)
100 parts by weight of white beads of paraffin wax SP-0165 (manufactured by Nippon Seiwa) purchased in a 4-neck flask with a stirrer, Liebig condenser, thermometer, 300 parts by weight of regenerated soybean oil (iodine value 117) After raising the temperature to 100 ° C. and stirring at the same temperature for 30 minutes, natural cooling was performed while stirring to obtain wax compound D.

(Fischer Trops wax compound production example)
A stirrer, a Liebig condenser, and a 4-neck flask with a thermometer are charged with 100 parts by weight of white beads of Fisher Trops Wax FT-0070 (manufactured by Nippon Seiwa) and 300 parts by weight of regenerated soybean oil (iodine value 117). The mixture was heated to 100 ° C. and stirred at the same temperature for 30 minutes, and then naturally cooled with stirring to obtain wax compound E.

(Heatset Offset Printing Ink Composition Example 1)
Carbon black (Mitsubishi Chemical Co., Ltd., DBP oil absorption 72 ml / 100 g, BET specific surface area 99 m ² / g), 20 parts by weight, gel varnish 74 parts by weight, petroleum solvent (AF Solvent No. 7 (JX Nippon Oil & Energy Corporation) Manufactured))) 5 wt., Base ink was prepared using three rolls according to a conventional method, and 1 part by weight of wax compound A (0.5 parts by weight of rice wax) was added to the heat-set offset printing ink composition. Example 1 was obtained.

Examples 2 to 6 and Comparative Examples 1 to 10 were obtained at the blending ratios shown in Table 1 in the same manner as in Example 1. The solid content of the wax compound is 25% by weight.

<Performance Evaluation Test (1) Melting Point Peak, Half Width>
From a melting endotherm (ΔH) curve obtained by heating 5 mg of a wax sample at a rate of 10 ° C./min from 20 ° C. using a high sensitivity differential scanning calorimeter (DSC-6200, manufactured by Seiko Instruments (SII)) The peak top melting point (Tm) and the half-value width of the observed peak were calculated in Table 2. The full width at half maximum (Wm) is the peak width at 50% height of the endothermic peak when the melting point (Tm) is measured by DSC. The smaller the full width at half maximum, the more uniform crystals are formed. It means that it shows the uniformity of the material.

Rice wax showed a sharp peak with respect to paraffin wax and Fischer Trops wax, indicating high crystallinity. Since stearyl stearate has a high purity, it similarly showed a sharp peak, but the melting point was very low.

<Performance Evaluation Test (2) Gloss>
The gloss evaluation test was carried out under the following printing conditions with a general pattern and density using a LITOPIA manufactured by Mitsubishi Heavy Industries, Ltd. as a heatset type lithographic printing machine, and the solid portion of the printed matter obtained was colored by Murakami. It was measured with a laboratory gloss meter GM26D.
CTP version: Fujifilm XP-F
Paper: Pearl Coat N manufactured by Mitsubishi Paper Industries Co., Ltd.
Printing speed: 600rpm
Chiller set temperature: 25 ° C
Number of printed copies: 20,000 copies available Practical level is “70” or more.

<Performance evaluation test (2) Cooling taken>
After the printing was completed under the above printing conditions, a transparent tape was applied to the third cooling, peeled off with a constant force, the amount of ink adhered at that time was visually confirmed, and the following criteria were confirmed. The practical level is “3” or higher.

1: Adhesion of ink is clearly large.
2: There is much ink adhesion 3: Normal adhesion 4; Slight ink adhesion 5: No ink adhesion

<Performance Evaluation Test (3) Guide Roll Remaining>
After completion of printing under the above printing conditions, a transparent tape was applied to a specific guide roll and peeled off with a constant force. The amount of ink adhered at that time was visually confirmed and confirmed according to the criteria in Table 3 above. The practical level is “3” or higher.

The above performance evaluation test results are shown in Table 1.

Since the melting point peak is sharp and the crystallinity is very high within the addition amount range of Examples 1 to 3, gloss and cooling are removed in a smaller amount than the paraffin wax and Fischer Trops wax of Comparative Examples 5 to 10. The guide remained at the practical level. In particular, the effectiveness of the rice wax is remarkable when the examples (for example, Examples 3 and 5 and Comparative Examples 3, 6, and 9) in which the addition amount is combined are compared.
If the amount of rice wax added is small as in Example 1, the surface cannot be sufficiently coated, and if it is large as in Example 5, unmelted residue occurs and the gloss slightly decreases. Since the stearyl stearates of Comparative Examples 2, 3, and 4 were low in melting point, they were cooled and showed no effect on the remaining guide, and the surface was roughened due to cooling and the remaining guide, and the increase in gloss was also low.

Note that it is essential to use rice wax derived from natural products in order to achieve both physical properties and “reducing environmental burden from the viewpoint of CO ₂ emissions”.

Claims (4)

A lithographic printing ink composition comprising rice wax, a binder resin, and vegetable oils. Rice wax has a crystalline melting point peak at 76-85 ° C. when measured with a differential scanning calorimeter,
The lithographic printing ink composition according to claim 1, wherein the half width is 8 ° C. or less. The lithographic printing ink composition according to claim 1 or 2, wherein the total amount of the lithographic printing ink composition comprises 0.5 to 2% by weight of rice wax. The printed matter formed by printing the lithographic printing ink in any one of Claims 1-3 on a base material.