A water quality stabilizer for water-based offset printing and a preparation method and use method thereof

Abstract

The present application belongs to the technical field of lithographic printing, and particularly relates to a tap water offset printing water quality stabilizer and a preparation method and use method thereof. The tap water offset printing water quality stabilizer comprises the following components in mass percentage: a buffer system 5-17%, a microbial bacteria liquid 1-10%, a printing plate protective agent 1-5%, a microbial maintenance system 5-20%, a clean plate enhancer 3-30%, a defoaming agent 0.5-5%, and the balance comprising water. The tap water offset printing water quality stabilizer prepared by the present application solves the problems that the dampening water is difficult to be standardized due to different standards of tap water hardness, pH, water quality and total solid content in different places, and that paper dust, paper fluff and grease gradually accumulate in the dampening water in the printing production process, resulting in increased waste water and decreased printing quality.

Description

Technical Field

[0001] This invention belongs to the field of offset printing technology, specifically relating to a water quality stabilizer for tap water offset printing, its preparation method, and its application method. Background Technology

[0002] In existing offset printing technology, to facilitate the formation of a dampening film, alcohol, isopropanol (IPA), or other alcohol or ether substitutes must be added to the dampening solution to reduce the surface tension of water. For a long time, attempts have been made to improve the formulation of inks or dampening solutions, or to add alcohol substitutes (all alcohols or ethers, such as propylene glycol, ethylene glycol, glycerin, propylene glycol methyl ether, etc.) to the dampening solution or ink to replace the use of alcohol and isopropanol (IPA). However, these substitutes cannot completely replace alcohol or isopropanol (IPA). Therefore, although dampening solutions containing these substitutes are labeled as "alcohol-free," they are not actually completely alcohol-free; the alcohol content is generally less than 5 wt%.

[0003] Invention patent ZL201510662688.4 is the first in China and internationally to design and successfully implement a zero-alcohol lithographic printing system. This system contains no alcohols, ethers or their substitutes in the dampening water, effectively solving the above problems. However, during the implementation of this system, paper dust, paper fibers and grease gradually accumulate in the dampening water, leading to increased wastewater and decreased printing quality. Furthermore, different standards for tap water hardness, pH, water quality and total solids content vary from place to place, which has caused difficulties in promoting and implementing the above system. Summary of the Invention

[0004] The purpose of this invention is to provide a tap water-based offset printing water quality stabilizer and its preparation and application methods, in order to solve the problems of inconsistent standards for tap water hardness, pH, water quality and total solids content in different regions, which makes it difficult to standardize dampening water, and the gradual accumulation of paper dust, paper fibers and grease in dampening water during the printing process, leading to increased wastewater and decreased printing quality.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solutions.

[0006] The first aspect of the present invention discloses a tap water offset printing water quality stabilizer, which comprises the following components in weight percentage: 5-17% buffer system, 1-10% microbial liquid, 1-5% printing plate protectant, 5-20% microbial maintenance system, 3-30% plate cleaning enhancer, 0.5-5% defoamer, and the balance being water.

[0007] The plate cleaner here reduces the surface tension of water, allowing the water film to quickly cover the blank areas, ensuring good coverage even at high speeds and preventing smudging on the blank areas. It also enables the stabilizer to spread quickly on the blank areas, resulting in excellent wetting. When ink gets on the blank areas due to plate dragging or other reasons, it quickly removes the ink layer, allowing printing to proceed smoothly without the need for manual plate cleaning.

[0008] Under high-speed friction, the oxide film layer on the blank areas of the printing plate will wear away. If not repaired in time, it will greatly affect the thickness of the water film and the hydrophilicity of the blank areas, making them prone to smudging and hindering normal printing. The main function of the printing plate protectant is to enhance the hydrophilicity of the blank areas, making it easier for the water film to cover them and reducing wear on the blank areas. It can also quickly regain balance even after the machine stops. Secondly, it can also increase the viscosity of the stabilizer, improve the water absorption function, and make it more convenient to use.

[0009] In a preferred embodiment of the present invention, the buffer system is a composition of citric acid, sodium citrate, and EDTA-2Na, wherein the mass ratio of citric acid:sodium citrate:EDTA-2Na is (1-6):(1-6):(1-2). This buffer system can, on the one hand, adjust the pH of the dampening water to maintain it between 4.5 and 6.0, ensuring optimal dampening effect; on the other hand, it can neutralize and complex calcium, magnesium, and iron ions in tap water, reducing water hardness and conductivity, maintaining optimal printing water quality, and preventing ions from calcifying the water rollers or ink rollers, thus affecting water or ink transfer.

[0010] In a preferred embodiment of the present invention, the microbial culture comprises lignin-degrading microorganisms, cellulose-degrading microorganisms, and lipid-degrading microorganisms, wherein the ratio of lignin-degrading microorganisms to cellulose-degrading microorganisms to lipid-degrading microorganisms is (1-3):(1-3):(1-3). These microbial cultures are commercially available, and their bacterial count is measured based on their original commercial sample concentration and volume. The bacterial concentration in the culture is typically not less than 100,000 cells / mL.

[0011] The microorganisms in the microbial liquid of the tap water offset printing water quality stabilizer of this invention have mutual and symbiotic effects, forming a state conducive to optimal printing damping. The microbial liquid can convert lignin in paper ash and paper fibers into coumarin, coniferyl alcohol, sinigrin, etc.; degrade cellulose in paper ash and paper fibers to obtain formic acid, cellulose acid, glucose, etc.; and degrade oils to obtain glycerol, citric acid, etc. The above metabolites can become nutrients for each other. While removing impurities in the water tank and reducing wastewater discharge, it realizes the transformation of waste into treasure. The metabolites enhance the damping function in tap water offset printing production.

[0012] In a preferred embodiment of the present invention, the printing plate protectant is gum arabic or CMC.

[0013] Preferably, the microbial maintenance system comprises soluble starch, potassium dihydrogen phosphate, ammonium nitrate, manganese chloride, white sugar, and sodium chloride, wherein the mass ratio of soluble starch: potassium dihydrogen phosphate: ammonium nitrate: manganese chloride: white sugar: sodium chloride is (10-15):(1-3):(1-3):(0-2):(3-5):(0-2). When manganese chloride and sodium chloride are present in the microbial maintenance system, they can provide the basic elements required for the life of the microbial community.

[0014] In a preferred embodiment of the present invention, the cleaning enhancer is soapberry extract or tea saponin.

[0015] In a preferred embodiment of the present invention, the lignin-degrading microorganisms are one or more of *Plasmodium chrysosporium*, *Trametes versicolor*, and *Schizophyllum commune*; the cellulose-degrading microorganisms are one or more of *Ruminococcus*, *Succinylcholine-producing filamentous bacilli*, *Vibrio fibrinolyticus*, *Agaricus*, *Trichophyton*, *Pterocaryon*, and *Fomitopsis*; and the oil-degrading microorganisms are one or more of *Propionibacterium*, *Malassezia*, *Staphylococcus*, and *Candida*.

[0016] In this invention, the balance including water not only means that the balance is entirely water, but also includes the balance being water and other inert components. Here, inert components refer to components that do not affect the effectiveness of this invention or the dampening and printing process, such as various impurities that inevitably mix into the water.

[0017] A second aspect of the present invention provides a method for preparing a water quality stabilizer for tap water offset printing, comprising the following steps:

[0018] A. Weigh the plate protectant, plate cleaner, and defoamer separately, and prepare the microbial inoculum and microbial matrix.

[0019] Backup systems and buffer systems are in place;

[0020] B. Add water to the reaction vessel, and add the raw materials from step A to the reaction vessel to dissolve them. After stirring evenly, the water quality stabilizer for tap water offset printing is obtained.

[0021] In a third aspect, the present invention provides a method for using a tap water offset printing water quality stabilizer, which involves diluting the tap water offset printing water quality stabilizer with 45 to 100 times the amount of water, adding it to the water tank of the printing press, and then starting the printing press normally.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) This invention is based on patent ZL201510662688.4. This invention does not contain volatile components, the concentration is stable during the printing process, the color difference of the printed product is small, and the printing stability is good after the machine is turned on; it does not require the blanket to be piled up and the paper is not easily deformed, and the registration of the front and back sides is accurate.

[0024] (2) The tap water offset printing water quality stabilizer described in this invention does not contain volatile components and has the advantages of being non-flammable, non-flammable, and safe to transport and store. At the same time, the ingredients are natural and environmentally friendly components, which can not only degrade paper dust, paper fibers and grease, reduce wastewater in the printing production process and save pollution control costs, but also have no pollution to the environment, protect the health of printing workers, and greatly help improve the air quality of the printing production environment.

[0025] (3) During the printing process, the water quality stabilizer of the tap water offset printing described in this invention has a stable concentration and good printing stability after the machine is turned on. It can quickly achieve water-ink balance, and the thinner water film will not overly dilute the ink, making the original ink film more vivid and full. It can restore the color with less ink, and the printed color difference is small. The blanket and paper are not easily deformed. The registration of the front and back sides is accurate. It does not require special requirements from the user, does not change the user's habits, and has wide adaptability.

[0026] (4) This stabilizer can be promoted to various models and users, and the overall cost of consumables can be reduced by more than 90%.

[0027] (5) This invention is a completely new product, different from previous dampening solutions and also different from stabilizers in other water supply systems. This stabilizer is specifically designed for printing presses. Detailed Implementation

[0028] The present invention will be further described below through specific embodiments.

[0029] Example 1

[0030] Prepare a tap water-based offset printing water quality stabilizer based on 100 parts by weight. The specific contents are: 5 parts buffer system, 10 parts microbial culture solution, 1 part printing plate protectant, 20 parts microbial maintenance system, 3 parts plate cleaning enhancer, 5 parts defoamer, and the remainder being water. Prepare the tap water-based offset printing water quality stabilizer according to the following steps:

[0031] A. Prepare a buffer system according to the mass ratio of citric acid: sodium citrate: EDTA-2Na of 1:1:1 for later use;

[0032] Prepare a microbial culture solution with a bacterial count ratio of *Proteus chrysosporium*: *Ruminococcus*: *Propionibacterium* of 1:1:1 for later use;

[0033] A microbial maintenance system was prepared with soluble starch, potassium dihydrogen phosphate, ammonium nitrate, manganese chloride, white sugar, and sodium chloride in a mass ratio of 10:1:1:2:3:1 for later use.

[0034] Prepare resoluble high-molecular-weight natural compounds such as gum arabic and natural and environmentally friendly soapberry extract for later use;

[0035] B. Add water to the reaction vessel, and then add the raw materials from step A to the reaction vessel to dissolve them. After stirring the mixture evenly, you will get the experimental sample 1 of the tap water offset printing water quality stabilizer.

[0036] Example 2:

[0037] Prepare a tap water-based offset printing water quality stabilizer based on 100 parts by weight. The specific contents are: 17 parts buffer system, 1 part microbial inoculum, 2 parts printing plate protectant, 10 parts microbial maintenance system, 30 parts plate cleaning enhancer, 0.5 parts defoamer, and water as the balance. Prepare the tap water-based offset printing water quality stabilizer according to the following steps: A. Prepare a buffer system according to the mass ratio of citric acid: sodium citrate: EDTA-2Na 3:2:1 for later use;

[0038] Prepare a microbial culture solution with a bacterial ratio of Schizophyllum commune: Succinic acid-producing filamentous bacteria: Malassezia in a ratio of 1:1:3 for later use;

[0039] The mass ratio of soluble starch, potassium dihydrogen phosphate, ammonium nitrate, manganese chloride, white sugar, and sodium chloride is 15:

[0040] A microbial maintenance system with a ratio of 3:1:2:5:0 was prepared for later use.

[0041] B. Take the resoluble high molecular weight natural compound CMC and natural and environmentally friendly tea saponin for later use; C. Add the remaining water to the reaction vessel, and add the raw materials from step A to the reaction vessel to dissolve them. After stirring the whole mixture evenly, the experimental sample 2 of the tap water offset printing water quality stabilizer is obtained.

[0042] Example 3:

[0043] Prepare a tap water-based offset printing water quality stabilizer based on 100 parts by weight. The specific contents are: 10 parts buffer system, 5 parts microbial inoculum, 3 parts printing plate protectant, 20 parts microbial maintenance system, 15 parts plate cleaning enhancer, 3 parts defoamer, and water balance. Prepare the tap water-based offset printing water quality stabilizer according to the following steps: A. Prepare a buffer system according to the mass ratio of citric acid: sodium citrate: EDTA-2Na 1:2:2 for later use;

[0044] Prepare a microbial culture solution with a bacterial count ratio of *Proteus xanthosporium*: *Vibrio cytolyticus*: *Candida* of 3:2:1 for later use;

[0045] A microbial maintenance system was prepared with soluble starch, potassium dihydrogen phosphate, ammonium nitrate, manganese chloride, white sugar, and sodium chloride in a mass ratio of 12:2:2:0:4:1 for later use.

[0046] A. Take the resoluble high-molecular-weight natural compound gum arabic and natural and environmentally friendly soapberry extract for later use; B. Add the remaining water to the reaction vessel, and add the raw materials from step A to the reaction vessel to dissolve them. After stirring the whole mixture evenly, the experimental sample 3 of the tap water offset printing water quality stabilizer is obtained.

[0047] Example 4:

[0048] Prepare a tap water-based offset printing water quality stabilizer based on 100 parts by weight. The specific contents are: 8 parts buffer system, 2 parts microbial culture solution, 4 parts printing plate protectant, 8 parts microbial maintenance system, 6 parts plate cleaning enhancer, 1 part defoamer, and water as the balance. Prepare the tap water-based offset printing water quality stabilizer according to the following steps:

[0049] A. Prepare a buffer system with a bacterial count ratio of citric acid: sodium citrate: EDTA-2Na of 1:6:1 for later use;

[0050] Prepare a microbial culture solution with a mass ratio of Trametes versicolor: Fomitopsis: Staphylococcus aureus of 3:1:2 for later use;

[0051] A microbial maintenance system was prepared with soluble starch, potassium dihydrogen phosphate, ammonium nitrate, manganese chloride, white sugar, and sodium chloride in a mass ratio of 13:1:1:1:3:1 for later use.

[0052] Prepare resoluble high-molecular-weight natural compounds such as CMC and natural and environmentally friendly tea saponins for later use;

[0053] B. Add the remaining water to the reaction vessel, and then add the raw materials from step A to the reaction vessel to dissolve them. After stirring the mixture evenly, you will get the experimental sample 4 of the tap water offset printing water quality stabilizer.

[0054] Example 5:

[0055] Prepare a tap water-based offset printing water quality stabilizer based on 100 parts by weight. The specific contents are: 16 parts buffer system, 3 parts microbial culture solution, 3 parts printing plate protectant, 18 parts microbial maintenance system, 17 parts plate cleaning enhancer, 4 parts defoamer, and water as the balance. Prepare the tap water-based offset printing water quality stabilizer according to the following steps:

[0056] A. Prepare a buffer system according to the mass ratio of citric acid: sodium citrate: EDTA-2Na 6:2:1 for later use;

[0057] Prepare a microbial culture solution with a bacterial count ratio of *Proteus chrysosporus*: *Agaricus*: *Candida* of 3:3:1 for later use;

[0058] A microbial maintenance system was prepared with soluble starch, potassium dihydrogen phosphate, ammonium nitrate, manganese chloride, white sugar, and sodium chloride in a mass ratio of 15:3:1:1:5:2 for later use.

[0059] Prepare resoluble high-molecular-weight natural compounds CMC and natural and environmentally friendly soapberry extract for later use;

[0060] B. Add the remaining water to the reaction vessel, and then add the raw materials from step A to the reaction vessel to dissolve them. After stirring the mixture evenly, you will get the experimental sample 5 of the tap water offset printing water quality stabilizer.

[0061] Example 6:

[0062] Prepare a tap water-based offset printing water quality stabilizer based on 100 parts by weight. The specific contents are: 5 parts buffer system, 1 part microbial culture solution, 5 parts printing plate protectant, 12 parts microbial maintenance system, 12 parts plate cleaning enhancer, 2 parts defoamer, and water as the balance. Prepare the tap water-based offset printing water quality stabilizer according to the following steps:

[0063] A. Prepare a buffer system according to the mass ratio of citric acid: sodium citrate: EDTA-2Na of 2:3:2 for later use;

[0064] Prepare a microbial inoculum solution with a bacterial count ratio of 1:1:3 for use by Ganoderma lucidum, Rhizoma et Radix, and Propionibacterium.

[0065] A microbial maintenance system was prepared with soluble starch, potassium dihydrogen phosphate, ammonium nitrate, manganese chloride, white sugar, and sodium chloride in a mass ratio of 15:3:1:2:5:2 for later use.

[0066] Prepare resoluble high-molecular-weight natural compounds such as CMC and natural and environmentally friendly tea saponins for later use;

[0067] B. Add the remaining water to the reaction vessel, and then add the raw materials from step A to the reaction vessel to dissolve them. After stirring the mixture evenly, you will get the experimental sample 6 of the tap water offset printing water quality stabilizer.

[0068] Comparative Example

[0069] The experimental samples 1-6 obtained in the above embodiments, and the control samples A (national standard tap water), B (microbial solution removed from experimental sample 1), C (microbial support system removed from experimental sample 1), D (alcohol), and E (a commercially available brand of alcohol-free dampening solution) were diluted with 49 times their weight of water to a 2wt% aqueous solution and directly added to the water tank of the Beiren 45A newspaper rotary press for normal printing. The number of printed sheets from start-up to stable printing (also known as "number of scrapped printed sheets"), the amount of water at stable printing (generally, the lower the percentage of water at stable printing, the better, as a lower water amount allows for greater space for water-ink balance adjustment), color difference of printed matter, VOCs residue of printed matter, VOCs residue of water in the water tank, and solid content of water in the water tank after 7 days of production were compared in the following experiments. (The water used for wetting all the above samples was the same type of water that meets the national standard for drinking water GB5749-2006. The printing process, printing machine type, printing materials, and printing operation were all the same.) The results of the printing performance index test are shown in Table 1 below.

[0070] Table 1. Results of Printing Performance Indicators Measurement

[0071]

[0072] Note: 1. During stable printing, the printing water content (%) is inversely proportional to the stability of the water film on the printing plate surface. The more stable the water film, the lower the printing water content. 2. VOCs are detected by a portable non-methane total hydrocarbon detector. 3. The solid content is detected by vacuum distillation and drying weighing method.

[0073] The following conclusions can be drawn from Table 1:

[0074] 1. Compared with control sample A (city tap water), experimental samples 1-6 showed significantly more stable water film on the printing plate, significantly reduced printing water volume, and reduced the number of scrapped prints by up to 80%.

[0075] 2. Compared with control sample AE, experimental samples 1-6 showed a significant reduction in water solids content in the water tank after 7 days of printing production, proving that the microbial community in the water quality stabilizer of this invention has a significant degradation effect on paper dust, paper fibers and grease.

[0076] 3. Compared with control sample AE, experimental samples 1-6 reduced the amount of water used during stable printing by 25%, proving that the microbial degradation products in the water quality stabilizer of the present invention have an auxiliary dampening effect.

[0077] 4. Compared with control sample C, experimental samples 1-6 reduced the water content during stable printing by 40% and reduced the number of waste prints by 60-70% during startup. This proves that the buffer of the present invention not only ensures a stable pH value for the wetting system, but also has the functions of cleaning the plate and stabilizing printing.

[0078] 5. Comparing experimental samples 1-6 with control samples D and E, the water volume during stable printing and the number of waste sheets at startup are similar, but the VOCs residue in the printed matter, the VOCs residue in the water tank, and the color difference in the printed matter are significantly reduced. This indicates that the present invention has the technical effects of being green and environmentally friendly, reducing color difference, improving hue stability, and improving the quality of printed matter.

[0079] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A water quality stabilizer for offset printing of tap water, characterized by, The composition comprises the following components: 5-17% of buffer system, 1-10% of microbial solution, 1-5% of printing plate protective agent, 5-20% of microbial maintenance system, 3-30% of clean plate enhancer, 0.5-5% of defoaming agent, and the rest is water; The microbial solution comprises lignin-degrading microorganisms, cellulose-degrading microorganisms and oil-degrading microorganisms, wherein the ratio of the number of the lignin-degrading microorganisms, the cellulose-degrading microorganisms and the oil-degrading microorganisms is (1-3):(1-3):(1-3); the clean plate enhancer is soap extract or tea saponin; The lignin-degrading microorganisms are one or more of Phanerochaete chrysosporium, Trametes versicolor and Schizophyllum commune; the cellulose-degrading microorganisms are one or more of Peptostreptococcus, Succinogenes, Cellulomonas, Butyricum, Hypholoma, Guepin, Fomes; and the oil-degrading microorganisms are one or more of Propionibacterium, Malassezia, Staphylococcus and Candida.

2. The tap water offset printing water quality stabilizer according to claim 1, characterized by, The buffer system is a combination of citric acid, sodium citrate and EDTA-2Na, wherein the mass ratio of citric acid:sodium citrate:EDTA-2Na is (1-6):(1-6):(1-2).

3. The tap water offset printing water quality stabilizer according to claim 1, characterized by, The printing plate protective agent is gum arabic or CMC.

4. The tap water offset printing water quality stabilizer according to claim 1, characterized by, The microbial maintenance system is soluble starch, potassium dihydrogen phosphate, ammonium nitrate, manganese chloride, white sugar and sodium chloride, wherein the mass ratio of soluble starch:potassium dihydrogen phosphate:ammonium nitrate:manganese chloride:white sugar:sodium chloride is (10-15):(1-3):(1-3):(0-2):(3-5):(0-2).

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