KR20060064259A - Ink composition for offset printing - Google Patents

Abstract

The ink composition for offset printing includes 5 to 35% by weight of colorant, 50 to 90% by weight of vehicle, 0.01 to 5% by weight of water-soluble organics, 0.01 to 5% by weight of phosphoric acid solution, 0.01 to 5% by weight of silicon compound and 0.01 to 1% by weight of nitrate. Include. Since the offset printing ink composition is capable of offset printing using only pure water as the moist solution, it can provide high-quality printing performance as well as providing an environment-friendly and excellent working environment.

Description

Ink composition for offset printing

1 is a photograph showing a state of a paper plate after printing according to the first embodiment of the present invention.

Figure 2 is a photograph showing the state of the paper plate after printing according to the second embodiment of the present invention.

3 is a photograph showing a state of a paper plate after printing according to a third embodiment of the present invention.

4 is a photograph showing a state of a paper plate after printing according to a fourth embodiment of the present invention.

5 is a photograph showing a state of a paper plate after printing according to a fifth embodiment of the present invention.

6 is a photograph showing a state of a paper plate after printing according to a sixth embodiment of the present invention.

7 is a photograph showing a state of a paper plate after printing according to Comparative Example 1. FIG.

The present invention relates to an ink composition for offset printing, and more particularly, to an offset ink composition which enables offset printing with pure water only.

In general, offset printing is a printing method that is printed on a flat plate using water and oil repulsion principle, unlike convex, intaglio, and intaglio printing. The printing machine basically consists of a plate copper, a rubber copper (blanket copper), and a pressurized water. And the ink are transferred to the plate copper to form an image, and the formed image is transferred to the rubber copper to print on the printed object passing between the pressing and the rubber copper. In general, the printed material may be paper, film, iron plate or the like. The offset printing method is the most widely used printing method in the world since the printed material can be printed in various colors.

Since the printing plate used in offset printing is a flat plate having no unevenness, the surface of the flat plate has a special chemical treatment. In the printing plate, the water and the ink are simultaneously transferred to the pandong on the printing press, but the ink portion is filled with the caustic portion and the water is applied with the non-cinched portion so that the ink does not transfer.

Conventional offset printing liquors included mainly water and isopropyl alcohol (IPA) and some etch solutions. In the case of such a water solution is the cause of air pollution due to the evaporation of isopropyl alcohol, the vapor has been diffused inside the printing room causing a headache and nausea of workers. In addition, the etch solution contains a strong acid and is composed of various toxic substances, which causes water pollution when discharging the water.

The present invention has been made in view of the problems of the prior art as described above, and provides an offset printing ink composition which enables offset ink using only pure water as a water solution.

Offset printing ink composition according to an aspect of the present invention is a colorant 5 to 35% by weight, vehicle 50 to 90% by weight, water-soluble organics 0.01 to 5% by weight, phosphoric acid solution 0.01 to 5% by weight, silicone compound 0.01 to 5% by weight and Nitrate 0.01 to 1% by weight.

By using the ink composition for offset printing of the present invention, offset printing is possible even using pure water as the moist water solution, thereby reducing environmental pollution and improving working environment. Moreover, also in printing performance, a performance fall does not occur compared with the conventional offset ink.

Hereinafter, the present invention will be described in detail.

As the colorant, a pigment form is used, and various kinds of general colorants for offset inks may be used according to colors. If the colorant is less than 5% by weight, the printability is rapidly deteriorated due to a decrease in ink concentration, excessive fluidity, or an excessive amount of emulsification. If the colorant is more than 35% by weight, ink transfer defects or emulsification due to excessive solids in the ink are caused. The printability is deteriorated due to a decrease in amount, a decrease in concentration, and the like. Therefore, the colorant is included in the total ink composition 5 to 35% by weight. Preferably it is 10 to 15% by weight for yellow, 15 to 20% by weight for red, blue, black.

The vehicle includes a resin component, an oil component, a solvent component, a desiccant, a drying inhibitor, a wax, and the like in the ink composition. Generally, the resin is a rosin-modified phenol resin, an alkyd resin, a petroleum resin, and the like, soybean oil. , Kerosene and linseed oil are commonly used. As a solvent, a high boiling point petroleum solvent is generally used and consists of saturated hydrocarbons. Cobalt and manganese are generally used as a desiccant, and hydroquinone is generally used as a drying inhibitor. As the wax, polyethylene wax and polytetrafluoroethylene are generally used. When the vehicle component is 50% by weight or less, the amount of emulsification of the ink is reduced, the fluidity is reduced, and the printing aptitude is decreased. Your aptitude will fall. Thus, the vehicle is included in the total ink composition 50 to 90% by weight. Preferably from 80 to 90% by weight.

As the water-soluble organic substance, gum arabic, dextrin cellulose or carboxymethyl cellulose (CMC), guar gum, xanthan gum and the like can be used. It is preferable to use the water-soluble organic substance which contains a hydroxyl group and a carboxyl group simultaneously. The water-soluble organic material is hydrophilic and has a property of swelling well in water. In addition, the water-soluble organic material has a property of being strongly adsorbed with the metal surface, which is the non-fired portion, in the offset printing process, to reduce friction with the water roller and to prevent loss of the water by the water roller. The water-soluble organic material is transformed into a free acid having a weak acidity of pH 2.5 to 3.5 by reacting with the phosphoric acid solution.

The water-soluble organic substance is used in the form of a salt with sodium, potassium, calcium or magnesium.

When the content of the water-soluble organics is less than 0.01% by weight, the performance of non-sensitization (the ability to prevent ink from rising to the non-sensitized portion on the printing plate) is significantly reduced, whereas when the content of the water-soluble organics exceeds 5% by weight, the dispersibility of the ink And the amount of transition during printing drops sharply. Therefore, the water-soluble organic material is included in the total ink composition 0.01 to 5% by weight. Preferably 1 to 2 wt% is included.

The phosphoric acid solution contains isopropyl alcohol (IPA) or water as a solvent. It is also possible to use a mixed solution of isopropyl alcohol and water as the solvent. The phosphoric acid solution contains a phosphoric acid compound as a solute. As the phosphoric acid compound, metaphosphoric acid, orthophosphoric acid, polymethic acid, or the like can be used. The phosphoric acid solution is preferably mixed so that the weight ratio of the solvent and the solute is 6-8: 2-4 in order to make it slightly acidic.

The phosphoric acid compound reacts with the water-soluble organic material to transform the organic material into a free acid form. In particular, when the water-soluble organic material is Arabian rubber, the following reaction is performed with the Arabian rubber.

XCOOK + H ₃ PO ₄ → XCOOH + K ₂ H ₂ PO ₄

In Scheme 1, XCOOK represents arabic rubber forming a salt form with potassium ion and X represents the remainder of the Arabic rubber except for -COO- group.

By the reaction, the arabic rubber in the form of a salt is converted into arabic acid in the form of a free acid.

In the case of cellulose, the following reaction is carried out with the phosphate compound.

YCOONa + H ₃ PO ₄ → YCOOH + NaH ₂ PO ₄

In Scheme 2, YCOONa represents cellulose forming a salt form with sodium, and Y represents the remainder of the cellulose except the -COO- group.

As such, when the water-soluble organics in the form of the free acid are formed, they are more adsorbed to the plate than the water-soluble organics in the form of the salt. In addition, the water-soluble organics in the form of salts are also poorly detectable. Therefore, an acid such as phosphoric acid is added until the water-soluble organic substance becomes a free acid in order to improve adsorptivity and insensitivity.

The pH of the water-soluble organics in the form of the free acid formed by adding the phosphoric acid solution to the water-soluble organics is preferably 2.5 to 3.5. When the pH exceeds 3.5, since too much water-soluble organic substance in the form of salt remains, the desensitization effect is significantly lowered.

If the content of the phosphoric acid solution is less than 0.01% by weight, the water-soluble organics do not transfer to the free acid, while if the content of more than 5% by weight free phosphoric acid may be generated to damage the wire or contamination of the non-fire line. Therefore, the phosphoric acid solution is contained in the ink composition 0.01 to 5% by weight. Preferably 0.1 to 0.3 wt% is included.

Examples of the silicone compound include polyether polysiloxane copolymers, polymethylalkylsiloxanes, polyether modified polysiloxanes, and the like. The silicone compound serves to improve slip resistance, scratch resistance, adhesion resistance, and the like during printing. It also plays the role of antifoam. In particular, as the silicone compound, polyether modified polysiloxane is preferable, and more preferably polyether modified polydimethylpolysiloxane is used. The polyether-modified polydimethylsiloxane can modify the silicone chain by controlling the number of various organic substances and branches, and has the advantage of improving compatibility. In order to control the compatibility, the ratio of the polyether group may be adjusted, thereby affecting the surface tension. For example, the larger the composition of the dimethyl group, the lower the surface tension. It is also possible to control the polarity of the silicon structure by changing the polyether chain itself. The polyether chain is composed of ethylene oxide (EO) and propylene oxide (PO). Polyethylene oxide is polar and polypropylene oxide is nonpolar. Therefore, it is possible to change the polarity of the silicon compound by adjusting the ratio of ethylene oxide and propylene oxide. As another method for organic modification, a high surface tension can be obtained by replacing part or all of the methyl group of the dimethyl structure with an alkyl group having a long chain.

The polyethylene ether modified polysiloxane is stable at 150 ° C. or lower, but the polyether chain is thermally decomposed at a temperature higher than that. Therefore, a silicon compound having high thermal stability may be obtained by using a structure other than polyether. To this end, polyester and aralkyl groups may be added to the polyethylene ether-modified polysiloxane chain. Using the polyester and the aralkyl group can maintain a thermally stable state up to a temperature range of about 220 ° C.

Examples of compounds that can be used as the silicone compound are shown in the following formulas (I) to (III).

In Formula 1, X and Y are each an integer of 2 to 1500, and m is an integer of 1 to 29.

In Formula II, X is an integer of 2 to 1500.

In Formula III, R is methyl, ethyl, nonyl, m is an integer of 1 to 29, and n is an integer of 1 to 20.

When the content of the silicone compound is less than 0.01% by weight, the ability to lower the declarative tension is reduced, and the slip resistance, scratch resistance, etc. are poor, and when the content is more than 5% by weight, the viscosity of the ink is lowered and the transition of the ink is insufficient. In other words, printability such as lack of transfer power due to excessive slipperiness becomes poor. Preferably from 0.05 to 0.15% by weight.

As the nitrate, magnesium nitrate, zinc nitrate and the like can be used. Ammonium dichromate may be used instead of the nitrate of the present invention. However, the ammonium dichromate is excluded from the present invention because it is not only classified as a high-risk material, but also known as a strong oxidizing agent and requires special care in handling.

The nitrate acts as a corrosion inhibitor in the ink composition of the present invention. If enough nitrates are available, the allowable range of ethch usage can be extended.

If the content of the nitrate is less than 0.01% by weight, the action of the corrosion inhibitor does not occur in the ink composition. If the content is more than 1% by weight, the burner may be damaged or the non-burnable part may be contaminated in the ink composition. Therefore, the nitrate is contained in the ink composition 0.01 to 1% by weight. Preferably 0.1 to 0.5% by weight is included.

As a method of mixing the components for the preparation of the offset printing ink composition, it is possible to mix and stir each component at the same time, or separately prepared by mixing and stirring separately the water-soluble organics, phosphate solution, silicon-based compound and nitrate It may be added separately to the colorant and the vehicle dispersion and stirred. In addition, the water-soluble organics and the phosphate solution may be separately separated, mixed, and added to the remaining ingredients for further control of pH. In addition to the mixing method of the composition may be various combinations as needed.

Application of the ink composition of the present invention to an offset ink process allows printing to be achieved by only inserting water into the moistening device while maintaining the existing printing system. Therefore, the ink composition can not only reduce environmental pollution but also significantly improve the printing working environment.

Hereinafter, the present invention will be described in more detail with reference to specific embodiments.

Preparation of Ink Composition

Example 1

After dispersing 79 g of vehicle and 18 g of coloring material through a disperser, 2.7 g of a mixture of water-soluble organic rubber and phosphoric acid solution (IPA: orthophosphoric acid = 7: 3) (Arabic rubber: 2.43 g, phosphoric acid solution: 0.27 g) 0.1 g of polyether-modified polydimethylpolysiloxane (BYK-340; manufactured by BYK, Germany) and 0.2 g of magnesium nitrate, which are nitrates, were uniformly stirred at 50 rpm for 20 minutes at 150 rpm to prepare an ink composition for offset printing.

Example 2

After dispersing 79 g of a vehicle and 18 g of a coloring agent through a disperser, 2.7 g of a mixture of a water-soluble organic dextrin and a phosphoric acid solution (water: orthophosphoric acid = 7: 3) (Arabic rubber: 2.43 g, phosphoric acid solution: 0.27 g), 0.1 g of a polysiloxane polyether copolymer (TEGO GLIDE 410; manufactured by TEGO), which is a silicone compound, and 0.2 g of zinc nitrate, which are nitrates, were uniformly stirred at 150 rpm for 20 minutes to prepare an ink composition for offset printing.

Example 3

After dispersing 79 g of a vehicle and 18 g of a coloring agent through a disperser, 2.7 g of a mixture of water-soluble organic cellulose and a phosphoric acid solution (water: metaphosphoric acid = 7: 3) (Arabic rubber: 2.43 g, phosphoric acid solution: 0.27 g), 0.1 g of a polysiloxane polyether copolymer (TEGO GLIDE 100; manufactured by TEGO), which is a silicone compound, and 0.2 g of magnesium nitrate, which are nitrates, were uniformly stirred at 150 rpm for 20 minutes to prepare an ink composition for offset printing.

Example 4

After dispersing 79 g of a vehicle and 18 g of a coloring agent through a dispersing machine, 2.7 g of a mixture of water-soluble organic carboxymethyl cellulose (CMC) and a phosphoric acid solution (water: orthophosphoric acid = 7: 3) (Arabic rubber: 2.43 g, phosphoric acid solution) : 0.27 g), 0.1 g of alkyl-aryl-modified methyl polysiloxane (TEGO GLIDE 420; manufactured by TEGO), a silicon compound, and 0.2 g of magnesium nitrate, which are nitrates, are stirred uniformly at 50 ° C. for 20 minutes at 150 rpm for offset printing ink composition. Was prepared.

Example 5

After dispersing 79 g of vehicle and 18 g of coloring agent through a disperser, 2.7 g of a mixture of water-soluble organic guar gum and phosphate solution (water: orthophosphoric acid = 7: 3) (Arabic rubber: 2.43 g, phosphate solution) : 0.27g), 0.1 g of polysiloxane polyether copolymer (TEGO GLIDE 440; manufactured by TEGO), a silicon compound, and 0.2 g of zinc nitrate, which are nitrates, were uniformly stirred at 150 rpm for 20 minutes to prepare an ink composition for offset printing. Prepared.

Example 6

Vehicle 79 g and 18 g of coloring material were dispersed through a disperser, and then 2.7 g of a water-soluble organic substance (XANTHAN GUM) and a mixture of a phosphoric acid solution (water: orthophosphoric acid = 7: 3) (Arabic rubber: 2.43 g, a phosphoric acid solution) : 0.27 g), 0.1 g of polysiloxane polyether copolymer (TEGO GLIDE 450; manufactured by TEGO), a silicon compound, and 0.2 g of zinc nitrate, nitrate, were uniformly stirred at 150 rpm for 20 minutes at 150 rpm to prepare an ink composition for offset printing. Prepared.

Comparative Example 1

82 g of the vehicle and 18 g of the colorant were uniformly stirred at 50 rpm for 20 minutes at 150 rpm without any additives to prepare an ink composition for offset printing.

Test Example 1 (Print Test Results)

Master printing was performed to measure the physical properties of each of the offset printing ink compositions prepared in Examples 1 to 6 and Comparative Example 1, and the printing plate was actually printed using a paper plate to form an image. Wet water conditions were used only tap water. 300 sheets were printed for each ink composition. The print test results are shown in Table 1 below.

  ※ (good) 5-1 (bad) Item Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Printability 5 4 5 5 5 5 2 Print quality 5 5 5 5 5 5 2 Plate Status After Printing 4.5 5 5 5 5 5 2 ^{Note 1)} DM 32/38 32/38 32/38 32/38 32/38 32/38 30.5 / 36.5 ^{Note 2)} TV 6.0 6.0 6.0 6.0 6.0 6.0 7.0

Note 1) DM: As a method of measuring the viscosity of the ink, the spreading degree after 10 seconds and 60 seconds was measured using the SPREAD-METER.

Note 2) TV: The ink's tackness value indicates the stickiness of the ink and was measured using INK-O-METER.

In general, in the case of offset printing, the printing plate uses an aluminum PS plate, but in the case of master printing, a paper plate, an aluminum plate, or photo paper is used. In the case of the above experiment was performed using a paper plate having a poor printability.

Offset printing ink composition according to the present invention can be printed using only the pure water as a moist solution is environmentally friendly and can improve the printing working environment. In addition, the printing quality may be equal to or higher than that of conventional offset printing inks.

In addition, the ink composition for offset printing of the present invention has excellent desensitization properties, prevents corrosion of the printing plate surface, and has excellent front effect and printability, even though pure water is used as the water solution. To be able.

As described above, although described with reference to the preferred embodiment of the present invention, those skilled in the art will be variously modified without departing from the spirit and scope of the invention described in the claims below. And can be changed.

Claims (9)

5 to 35% by weight of the coloring material; Vehicle 50-90 weight percent; 0.01-5% by weight of water-soluble organics; 0.01-5% by weight of a phosphoric acid solution; 0.01 to 5 wt% silicone compound; And An offset printing ink composition comprising 0.01 to 1% by weight of nitrate. The ink composition for offset printing as claimed in claim 1, wherein the water-soluble organic substance contains a hydroxyl group and a carboxyl group. The ink composition of claim 2, wherein the water-soluble organic material comprises at least one organic material selected from the group consisting of gum arabic, dextrin, cellulose and carboxymethyl cellulose, guar rubber and xanthan rubber. The ink composition for offset printing according to claim 1, wherein the phosphate solution is dissolved in a solute isopropyl alcohol or water at a weight ratio of 2 to 4: 6 to 8, respectively. The ink composition of claim 4, wherein the phosphoric acid compound comprises at least one compound selected from the group consisting of metaphosphoric acid, orthophosphoric acid and polymethic acid. The ink composition of claim 1, wherein the silicone compound comprises at least one compound selected from the group consisting of polyether polysiloxane copolymers, polymethylalkylsiloxanes, and polyether modified polysiloxanes. The ink composition for offset printing according to claim 6, wherein the polyether-modified polysiloxanes are polyether-modified dimethylpolysiloxanes. The ink composition of claim 1, wherein the nitrate comprises at least one salt of magnesium nitrate and zinc nitrate. The ink composition of claim 1, wherein the water-soluble organic material is present in the form of a free acid having a pH of 2.5 to 3.5.

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