CN110746818A

CN110746818A - Pretreatment ink for water-based pigment ink and printing method thereof

Info

Publication number: CN110746818A
Application number: CN201911219446.2A
Authority: CN
Inventors: 王齐振; 孙志国; 秦国胜
Original assignee: Hongsam Digital Science & Technology Co Ltd
Current assignee: Hongsam Digital Science & Technology Co Ltd
Priority date: 2019-12-03
Filing date: 2019-12-03
Publication date: 2020-02-04

Abstract

The invention discloses a pretreatment ink suitable for water-based pigment ink, which is prepared from the following components in percentage by weight: a precipitant: 1-15%, ink absorber: 1-15%, wetting agent: 0.1-3%, resin crosslinking agent: 1-10%, viscosity modifier: 1-5%, organic co-solvent: 5-40%, pH stabilizer: 0.1-2%, bactericide: 0.05-0.5%, deionized water: the balance being. The pretreatment ink and the water-based pigment ink are sequentially printed on a base material according to requirements, the water-based pigment ink is accurately printed on a part printed by the pretreatment ink, a dispersion body in the water-based pigment ink can quickly react with a precipitator in the pretreatment ink and is absorbed by an ink absorber to form a clear pattern on the base material, and a resin in the water-based pigment ink is crosslinked with a crosslinking agent in the pretreatment ink to further improve the adhesion and fastness of the water-based pigment ink on the base material.

Description

Pretreatment ink for water-based pigment ink and printing method thereof

Technical Field

The invention relates to functional pretreatment ink for water-based pigment ink and a printing method thereof, belonging to the technical field of ink-jet digital printing and digital printing.

Background

In the prior art, screen printing, weak solvent ink direct injection, UV light curing ink direct injection and water-based pigment ink direct injection are generally used for manufacturing plane carrier printing media such as oil paintings, prints, building material decorative wallpaper, commodity packaging, commodity labels, printing and dyeing textiles, glass, metal and the like, textile printing and the like. Of these, screen printing processes are the least expensive, generally do not require steaming or water steaming, and are bright in color, good in light fastness and good in dry-cleaning fastness. However, the printing and printing process of the screen process requires a preliminary plate making process including: the steps of screen stretching, degreasing, drying, film base stripping, exposure, developing, drying, plate repairing, screen sealing and the like need to consume a large amount of manpower and material resources, plate washing and drying treatment is needed in the plate making process, a large amount of water is needed for washing, colored sewage which is difficult to treat is generated, and the environmental protection burden is increased.

The solvent of the weak solvent ink is a volatile organic liquid, which can adjust the viscosity of the ink-jet ink, dilute the monomer, adjust the surface tension, and dry. After the ink is printed on a printing stock, the solvent with strong volatility is quickly volatilized, and the solvent with weak volatility is infiltrated into the printing stock by virtue of the capillary action, so that the connecting material and the colorant left on the surface of the paper are fixed on the surface of the base material and have good fastness after being dried. Weak solvent inks are widely used for uncoated media. UV inks have a characteristic curing mode, i.e., they are rapidly cured by ultraviolet light without depending on penetration and evaporation, and are now widely used by inkjet printing. However, UV inks are costly, which directly affects the printing price of UV printed products. Currently, the field of ink jet printing is mainly wide pattern/image printing with a small number of printing copies. However, in the weak solvent ink and UV ink, a small amount of voc chemicals may be released by natural evaporation and during printing, causing some damage to the respiratory system, mucous membranes, lungs, etc. of the operator.

The water-based pigment ink mainly uses water as a solvent, has the advantages of stable ink color, high brightness, strong tinting strength, strong adhesion after printing, adjustable drying speed, strong water resistance and the like, and has weather resistance comparable to that of the traditional silk-screen, weak solvent ink and UV ink. The water-based ink does not contain volatile toxic organic solvent, so that the water-based ink has no adverse effect on the health of operators in the printing process and has no pollution to the atmospheric environment and the printed matter. In addition, the water-based ink has the characteristic of non-flammability, so that the hidden danger of flammability and explosiveness can be eliminated, the operating environment is improved, and the safety production is facilitated.

However, the aqueous pigment ink is difficult to achieve good wetting on many substrates, and unless the substrate is subjected to sizing and patterning separately, it is difficult to print on the substrate, especially on an uncoated medium, which greatly reduces the production efficiency and increases the difficulty and cost of digital printing with the aqueous pigment ink. Therefore, it is necessary to improve the applicability of the aqueous pigment ink to a substrate and to simplify the printing process of the aqueous pigment ink on the substrate.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, and provides the pretreatment ink suitable for the water-based pigment ink, which is printed on a substrate before the water-based pigment ink is printed, so that the covering power, the color depth, the definition color space and the fastness of the pigment ink can be effectively improved. In addition, the invention also provides a preparation method and a response method of the pretreatment ink.

According to a first aspect of the invention, a pretreatment ink suitable for aqueous pigment ink is provided, which is prepared from the following components in percentage by weight: a precipitant: 1-15%, ink absorber: 1-15%, wetting agent: 0.1-3%, resin crosslinking agent: 1-10%, viscosity modifier: 1-5%, organic co-solvent: 5-40%, pH stabilizer: 0.1-2%, bactericide: 0.05-0.5%, deionized water: the balance being.

Wherein the precipitating agent includes, but is not limited to: at least one of cationic polyacrylamide, inorganic metal salt, cationic quaternary ammonium salt and cationic modifier. Specifically, in the invention, the precipitant can adopt at least one of polyacrylamide, calcium chloride, calcium nitrate, aluminum nitrate, zinc nitrate, polyaluminum chloride, hexadecyl trimethyl ammonium chloride, octadecyl trimethyl ammonium chloride, dodecyl trimethyl ammonium chloride, Suzhou Hengwang chemical cation modifier HW-168B and Zhongshan southern refined cation modifier KN9511 with the molecular weight of less than 100 ten thousand on the market.

The ink absorber adopts nano silicon dioxide dispersion liquid and/or nano aluminum oxide dispersion liquid, specifically, the nano silicon dioxide dispersion liquid can select nano silicon dioxide dispersion liquid CPL-16 of high chemical engineering company, nano silicon dioxide dispersion liquid CL and CL-P of LUDOX company, nano silicon dioxide dispersion liquid 7520N of winning and creating company, nano aluminum oxide dispersion liquid VK-L01A of Hangzhou Zhi purification science and technology Limited company and JR14W, and the nano aluminum oxide dispersion liquid can select dispersible nano aluminum oxide B8014-BM35, B8014-BM45, B8014-BM36 and the like of Tianjin Boyuan high-new materials.

The resin cross-linking agent is an isocyanate cross-linking agent and/or a polycarbodiimide cross-linking agent, and specifically, in the invention, the isocyanate cross-linking agent can be an isocyanate cross-linking agent BK0 of Ningceddy corporation, an isocyanate cross-linking agent BI799 of Shanghai potential high-tech materials science and technology Limited, and a polycarbodiimide cross-linking agent PC-40 of Guangzhou Zoneng trade Limited.

The wetting agent is at least one of a nonionic surfactant, a silicone surfactant, an organic fluorine surfactant and a zwitterionic surfactant. Specifically, in the invention, the non-ionic surfactant adopts at least one of the following substances of the Toso TRITON X-100, ECOSURF EH-9, peregal O-15, OLFINE E1010, OLFINEEXP4200 of Japan Nissan chemical industry, Surfynol420, Surfynol440 and Dynol604, and the organic silicon surfactant can be selected from at least one of TEGO WET260, TEGO WET270, BYK-342 and BYK-333 of Germany BYK; the organic fluorine surfactant can be at least one selected from Capstone FS-3100, Zonyl 321 and Zonyl 8857A of DuPont; the zwitterionic surfactant can be one or more selected from carboxylic acid betaine, sulfobetaine, dodecyl amino propionic acid, etc.

The viscosity regulator is one or more of coconut oil diethanolamide, hydrogenated castor oil such as CO-40 and CO-60, polyvinylpyrrolidone such as PVPK-90, and polyethylene glycol ester compounds such as PEG-120 and PEG-150.

The organic cosolvent can adopt one or more of glycerol, diethylene glycol, 1, 6-hexanediol, 1, 3-butanediol, 1, 5-pentanediol, triethylene glycol, tetraethylene glycol, isopropanol, 1, 4-butanediol, 1, 3-propanediol, 1, 2-propanediol, sorbitol, polyethylene glycol 200, polyethylene glycol 400, polyethylene glycol 600, ethyl acetate, ethyl lactate, thiodiglycol, dipropylene glycol methyl ether, dipropylene glycol, ethanol, isobutanol, ethylene glycol, 1.2 hexanediol, ethylene glycol butyl ether, ethylene glycol tertiary butyl ether, diethylene glycol methyl ether, diethylene glycol diethyl ether, propylene glycol methyl ether and the like, so as to prevent the printing nozzle from drying and ensure smooth printing of the pre-treated ink. Further, in the present invention, the organic cosolvent is preferably one or more selected from ethanol, isopropanol, isobutanol, ethylene glycol, 1.2-hexanediol, 1.2-propylene glycol, ethylene glycol butyl ether, ethylene glycol tert-butyl ether, diethylene glycol methyl ether, diethylene glycol diethyl ether, propylene glycol methyl ether, dipropylene glycol methyl ether, ethyl acetate, ethyl lactate, etc., having a boiling point of less than 200 ℃.

The pH stabilizer may be at least one selected from acetic acid, formic acid, potassium hydrogen phthalate, mixed phosphate, citric acid, ammonium sulfate, ammonium chloride, triethanolamine, diethanolamine, monoethanolamine, sodium hydroxide, 2-aminoethanol, sodium tartrate and sodium citrate, and preferably at least one selected from triethanolamine, monoethanolamine, ammonium citrate, ammonium sulfate, ammonium chloride, sodium tartrate and 2-aminoethanol.

The bactericide is at least one of isothiazolinone bactericides such as Preventol D7, PROXEL GXL, and cason.

The invention utilizes the same charges on the surfaces of the particles in the water-based pigment ink to repel each other and be stable under certain conditions. The greater the thickness of the electric double layer, the greater the force of mutual repulsion and the more stable the particles. The precipitator added in the pretreatment ink can neutralize the charges on the surfaces of the particles, reduce the surface charge amount and the thickness of an electric double layer, so that the repulsion among the particles is reduced, flocculent aggregation occurs, and simultaneously, pigment particles and resin emulsion particles in the water-based pigment ink are fixed by the ink absorber while being rapidly precipitated, thereby forming a clear pattern. In addition, the pre-treatment ink cross-linking agent can improve the adhesive force of the resin in the water-based pigment ink on the substrate, so that the resin in the water-based pigment ink and the cross-linking agent in the pre-treatment ink are subjected to cross-linking reaction after printing is finished to form a compact resin film, and the scratch resistance and the water resistance of the ink on the substrate are improved.

The invention also provides a preparation process of the pretreatment ink, which comprises the following steps: the components with the weight percentage are mixed and stirred for 1 to 2 hours at the temperature of between 25 and 35 ℃ until the components are dissolved and mixed evenly, then the mixture is kept stand for 12 hours at room temperature and is filtered to obtain the pretreatment ink.

Wherein the filtering treatment comprises filtering the pre-treated ink by a PP filter element with the filtering precision of 3.0mm, an N6 nylon filter element with the filtering precision of 1.2 mu m, an N6 nylon filter element with the filtering precision of 0.8 mu m and an N6 nylon filter element with the filtering precision of 0.45 mu m in turn under the filtering pressure of less than 0.1 MPa.

The pretreatment ink prepared by the method has the following physical and chemical parameters at 20 ℃: viscosity: 2-15mpa.s, surface tension: 20-40mN/m, pH value: 6-8, conductivity < 10000 mus/cm and density: 0.7-1.4g/cm³。

In addition, the invention also provides an application method of the pretreatment ink, which comprises the following steps: the pretreatment ink and the water-based pigment ink are arranged on different channels of the same printer or a plurality of printers, and the pretreatment ink and the water-based pigment ink are sequentially subjected to ink-jet printing on the base material according to the required patterns, so that the water-based pigment ink is accurately printed on the part printed by the pretreatment ink, the two inks are overlapped, the water-based pigment ink is prevented from permeating downwards and diffusing to the periphery, the definition is improved, meanwhile, the thickness of the pigment accumulated on the surface of the base material is increased, and the covering power and the color depth of the pigment on the base material are improved; and drying the finished product at 45-70 ℃ for 1-3 minutes after printing is finished. Wherein, the drying mode includes but not limited to heating by using a quartz tube, infrared heating or hot air drying and the like. In addition, the printed base material can be printed according to the requirement, and the dried finished product is baked for 1-10 minutes at 50-180 ℃.

Here, the substrate used in the present invention is not particularly limited, and any substrate commonly used in the fields of digital printing and digital printing may be used, including, but not limited to, any one of uncoated wallpaper, corrugated paper, coated paper, PVC film, PET film, PP film, dupont Paper (PE), textiles, artificial leather, kraft paper, and the like.

The invention has the advantages that the pretreatment ink is printed on a substrate before the aqueous pigment ink is used for printing, and the subsequent aqueous pigment ink printing process, namely wet printing, can be carried out without any drying treatment, thereby saving energy. More importantly, the water-based pigment ink printed in the post-printing process is accurately printed on the part printed by the pre-treatment ink and is superposed with the part printed by the pre-treatment ink, the pre-treatment ink can effectively prevent the water-based pigment ink from permeating downwards and diffusing to the periphery, the definition of a printed pattern is improved, and meanwhile, the thickness of the pigment accumulated on the surface of the base material is increased, so that the covering power and the color depth of the pigment on the base material are improved. In addition, the resin crosslinking agent in the pretreatment ink reacts with hydroxyl, carboxyl and amino groups in the resin emulsion in the aqueous pigment ink to improve the crosslinking density and further improve the fastness of the pigment ink on a substrate. By utilizing the pretreatment ink and the printing mode, the base material can obtain a printing product with clear patterns without sizing and patterning, thereby reducing the working procedure of digital printing and printing, improving the applicability of the aqueous pigment ink to the base material, simplifying the working procedure of printing the aqueous pigment ink on the base material, effectively improving the production efficiency, reducing VOC (volatile organic compound) emission, reducing sewage emission, saving materials, reducing pollution and lowering comprehensive cost.

Detailed Description

The following further describes embodiments of the present invention with reference to specific examples. Unless otherwise specified, all the raw materials used in the present invention can be obtained commercially.

Example 1

The pretreatment ink suitable for the water-based pigment ink is prepared from the following components in percentage by weight: calcium nitrate: 2%, HW-168B: 0.7%, CPL-16: 5%, BI 799: 3%, coconut oil diethanolamide 3%, ethylene glycol: 30%, 1.2 propylene glycol: 10%, OLFINE E1010: 1%, triethanolamine: 0.5%, PROXEL GXL: 0.1%, deionized water: the balance being. The preparation process of the pretreatment ink-jet ink comprises the following steps: 1) adding calcium nitrate, coconut oil diethanolamide and deionized water into a reaction kettle, stirring at 30 ℃ until the calcium nitrate, the coconut oil diethanolamide and the deionized water are completely dissolved, adding CPL-16, BI799, HW-168B, ethylene glycol, 1.2 propylene glycol and OLFINE E1010, continuously stirring for 30 minutes, finally adding PROXEL GXL, stirring for 60 minutes, cooling to room temperature and standing for 12 hours; 2) and (3) filtering the pre-treated ink after standing by a PP filter element with the filtering precision of 3.0mm, an N6 nylon filter element with the filtering precision of 1.2 mu m, an N6 nylon filter element with the filtering precision of 0.8 mu m and an N6 nylon filter element with the filtering precision of 0.45 mu m in sequence under the filtering pressure of less than 0.1MPa to obtain the pre-treated ink.

Example 2

The pretreatment ink for the water-based pigment ink is prepared from the following components in percentage by weight: polyacrylamide: 0.1%, polyaluminum chloride: 3%, B8014-BM 35: 6%, PEG-120: 5%, 1, 2-propanediol: 17% and ethanol: 10%, propylene glycol methyl ether: 8%, dodecylaminopropionic acid: 1%, ammonium citrate: 0.5%, Preventol D7: 0.3%, deionized water: the balance being. The preparation process of the pretreatment ink is similar to that of example 1, and is not repeated herein.

Example 3

The pretreatment ink for the water-based pigment ink comprises the following components in percentage by weight: calcium chloride: 2%, 7520N: 10%, KN 9511: 5%, PC-40: 5%, CO-60: 2%, 1.2-propanediol: 20%, 1.2-hexanediol: 5%, diethylene glycol diethyl ether: 6%, BYK-342: 0.1%, 2-aminoethanol: 0.3%, PROXEL GXL: 0.1%, deionized water: the balance being. The preparation process of the pretreatment ink is similar to that of example 1, and is not repeated herein.

Example 4

A pretreatment ink-jet ink for pretreatment ink of water-based pigment ink comprises the following components in percentage by weight: octadecyl trimethyl ammonium chloride: 8%, VK-L01A: 15%, BK 0: 5%, PVP K90: 1%, ethylene glycol: 25%, dipropylene glycol methyl ether: 10%, Zonyl 321: 0.5%, sodium tartrate: 0.1%, Preventol D7: 0.3%, deionized water: the balance being. The preparation process of the pretreatment ink is similar to that of example 1, and is not repeated herein.

The physical and chemical properties of each of the pre-treatment inks prepared in examples 1 to 4 were measured at 20 ℃, and the results are shown in table 1:

TABLE 1 test results of physicochemical properties of pre-treated inks

The results of the printing fluency and the standby performance tests on each of the pretreated inks obtained in examples 1 to 4 are shown in table 2:

table 2 pre-treatment ink printing fluency and standby performance test results

From the test results in table 2, the pre-treatment ink prepared by the present invention has good printing fluency and standby performance.

The prepared pretreatment ink and the water-based pigment pretreatment ink commonly used in the field are sequentially printed on a plain cotton fabric, PU leather, DuPont paper and a PVC film substrate by the same printer or different printers according to required patterns, so that when the water-based pigment ink is accurately printed on the printed part of the pretreatment ink, the two inks are superposed, a dispersion body in the water-based pigment ink can rapidly react with a precipitator in the pretreatment ink and is absorbed by an ink absorber to form a clear pattern on the substrate, and resin in the water-based pigment ink is crosslinked with a crosslinking agent in the pretreatment ink to further improve the adhesion and fastness of the water-based pigment ink on the substrate. In addition, according to the difference of the base materials, the drying process of the base materials after printing is respectively as follows: the plain-weave baking temperature of the pure cotton is 160 ℃, and the time is 3 minutes. The baking temperature of PU leather and DuPont paper (PE material) is 100 ℃, and the baking time is 5 minutes. The temperature of the PVC film and the coated paper is 60 ℃, and the time is 2 minutes.

Observing the definition of the printed and dried finished product, wherein the definition grade is divided into three grades, wherein the A grade is as follows: the printed image has clear edge and no diffusion and mutual permeation phenomenon; b stage: the mutual permeation exists between the slightly diffused colors at the edge of the printed image; c level: the printed image has serious edge diffusion and color bleed, and cannot be imaged. The results of testing the print definition of various substrates after printing with the pretreatment inks of examples 1-4 and the same aqueous pigmented ink are shown in table 3.

Table 3 substrate print definition test results

The pretreated inks of examples 1-4 above and the same aqueous pigmented ink were printed on a substrate for color fastness testing, the results of which are shown in tables 4-5, respectively: wherein, the textile pure cotton plain weave, PU leather and DuPont paper are subjected to fastness test grading according to GB/T3920-: and (3) sticking and pulling the printing surface twice by using a 3M adhesive tape, and judging whether the adhesive force meets the requirement or not according to the area of the ink layer which is stuck and pulled. Specifically, the test process of the "stick-pull method" is as follows: 1) sticking the adhesive tape on the printing ink surface, and rolling for 3 times in one direction by using a press roller with constant load; 2) standing for 5min, and preparing a sample with a length of 20cm and a width of 1.5cm according to a T-type peel strength test method; 3): testing the T-shaped peeling strength of the prepared sample on a peeling tester; and 4): whether the adhesion force is qualified or not is judged according to the size of the peeling strength value (instead of the pull-off area of the ink layer) and the damage type, and the test result is classified into A, B, C, D four grades, wherein the A grade: the adhesive force is qualified if the separating force is larger than 2N and the ink layer is pulled off; b stage: the peeling force is larger than 2N, the ink layer is not pulled off, and the adhesive force is qualified; c level: the stripping force is less than 2N, the ink layer is pulled off, and the adhesive force is unqualified; d stage: the peel force was less than 2N and the ink layer was not pulled away, requiring replacement of the tape with better adhesion to the ink film and retesting until one of A, B, C events occurred.

TABLE 4 substrate print fastness test results

TABLE 5 fastness testing of ink layers of prints

From the results in tables 3 to 5, it is clear that the aqueous pigment inks of the present invention have good definition and color fastness on various substrates by the pretreatment ink and the printing method. In addition, the pretreatment ink and the printing mode can realize the on-line coating, and reduce the procedures of digital printing and printing; moreover, the invention can use a 'wet beating' mode: namely, after the pretreatment ink is printed and led onto the base material, the patterns/designs can be directly printed by using the water-based pigment ink without drying treatment, thereby omitting the pretreatment drying process and saving energy. The covering power, the color depth and the color space of a finished product are improved, and the pretreatment ink disclosed by the invention is adopted for pretreatment printing, so that the production efficiency can be effectively improved, the VOC (volatile organic compound) emission can be reduced, the sewage emission can be reduced, the material can be saved, the pollution can be reduced, and the comprehensive cost can be reduced.

The present invention has been described in detail with reference to the preferred embodiments. However, variations and additions to the embodiments will become apparent to those of ordinary skill in the art upon a reading of the foregoing description. It is the intention of the applicants that all such variations and additions fall within the scope of the claims. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Any modification and improvement of this product, and the substitution and use of the same or similar substances within the scope or range of patents, shall fall within the scope of protection of this invention.

Claims

1. A pretreatment ink suitable for an aqueous pigment ink, characterized in that: the composition comprises the following components in percentage by weight: a precipitant: 1-15%, ink absorber: 1-15%, wetting agent: 0.1-3%, resin crosslinking agent: 1-10%, viscosity modifier: 1-5%, organic co-solvent: 5-40%, pH stabilizer: 0.1-2%, bactericide: 0.05-0.5%, deionized water: the balance being.

2. The pretreatment ink according to claim 1, wherein: the precipitant is at least one of cationic polyacrylamide, inorganic metal salt, cationic quaternary ammonium salt and cationic modifier; the ink absorber is nano silicon dioxide dispersion liquid and/or nano aluminum oxide dispersion liquid.

3. The pretreatment ink according to claim 1, wherein: the resin cross-linking agent is an isocyanate cross-linking agent and/or a polycarbodiimide cross-linking agent; the wetting agent is at least one of a nonionic surfactant, a silicone surfactant, an organic fluorine surfactant and a zwitterionic surfactant.

4. The pretreatment ink according to claim 1, wherein: the viscosity regulator is at least one of coconut oil diethanolamide, hydrogenated castor oil, polyvinylpyrrolidone and polyethylene glycol ester compounds; the organic cosolvent is at least one of glycerol, diethylene glycol, 1, 6-hexanediol, 1, 3-butanediol, 1, 5-pentanediol, triethylene glycol, tetraethylene glycol, isopropanol, 1, 4-butanediol, 1, 3-propanediol, 1, 2-propanediol, sorbitol, polyethylene glycol 200, polyethylene glycol 400, polyethylene glycol 600, ethyl acetate, ethyl lactate, thiodiglycol, dipropylene glycol methyl ether, dipropylene glycol, ethanol, isobutanol, ethylene glycol, 1.2 hexanediol, ethylene glycol butyl ether, ethylene glycol tertiary butyl ether, diethylene glycol methyl ether, diethylene glycol diethyl ether and propylene glycol methyl ether.

5. The pretreatment ink according to claim 1, wherein: the pH stabilizer is at least one of acetic acid, formic acid, potassium hydrogen phthalate, mixed phosphate, citric acid, ammonium sulfate, ammonium chloride, triethanolamine, diethanolamine, monoethanolamine, sodium hydroxide, 2-aminoethanol, sodium tartrate and sodium citrate; the bactericide is an isothiazolinone bactericide.

6. The pretreatment ink according to any one of claims 1 to 5, wherein: at 20 ℃, the viscosity of the pretreatment ink is 2-15mPa.s, the surface tension is 20-40mN/m, the pH value is 6-8, the conductivity is less than 10000 mu s/cm, and the density is 0.7-1.4g/cm³。

7. A method of preparing a pre-treatment ink according to any one of claims 1 to 6, characterized in that: the preparation method comprises the following steps: and stirring the precipitator, the ink absorber, the wetting agent, the organic cosolvent, the viscosity regulator, the resin cross-linking agent, the pH stabilizer, the bactericide and the deionized water at 25-35 ℃ for 1-2 hours until the mixture is dissolved and mixed uniformly, standing at room temperature for 12 hours, and filtering to obtain the pretreatment ink.

8. The method of claim 7, wherein: the filtration treatment comprises filtering the pre-treated ink sequentially through a PP filter element with the filtration precision of 3.0mm, an N6 nylon filter element with the filtration precision of 1.2 mu m, an N6 nylon filter element with the filtration precision of 0.8 mu m and an N6 nylon filter element with the filtration precision of 0.45 mu m under the filtration pressure of less than 0.1 MPa.

9. A method of applying a pre-treatment ink as claimed in any one of claims 1 to 6, wherein: and printing the pretreatment ink and the water-based pigment ink on a base material according to the required flower type/pattern in sequence, and drying the finished product after printing.

10. The method of application according to claim 9, characterized in that: the base material is any one of uncoated wallpaper, corrugated paper, coated paper, PVC film, PET film, PP film, DuPont paper, pure cotton, polyester cotton, leather and polyester base material.