Environment-friendly ink for ink-jet printing and preparation method thereof

Abstract

This invention discloses an environmentally friendly inkjet ink and its preparation method. The raw materials of this environmentally friendly inkjet ink, by weight, consist of 55-82 parts of an organic solvent mixture, 5-26 parts of a binder resin, 5-6 parts of a colorant, 1 part of a plasticizer, 5 parts of a conductive agent, 1 part of a leveling agent, and 1-2 parts of other additives. The organic solvent mixture is a single organic solvent A, or a mixture of organic solvent A with one or more of organic solvents B and C. This environmentally friendly inkjet ink completely avoids the need for large amounts of methyl ethyl ketone (MEK) solvent in traditional inks, overcoming the limitation of MEK's strong irritating odor, thus significantly improving its environmental performance. Simultaneously, this ink exhibits good stability, suitable fast drying, and excellent adhesion. During inkjet printing, the print is clear and not prone to clogging the printhead, demonstrating excellent durability.

Description

Technical Field

[0001] This invention belongs to the field of inkjet printing, specifically relating to an environmentally friendly inkjet ink and its preparation method. Background Technology

[0002] With rising consumer spending power and heightened awareness of quality and safety, the market is demanding higher standards for the standardization and traceability of product information labeling. In sectors directly related to health and well-being, such as food, pharmaceuticals, and cosmetics, regulations in many countries mandate the labeling of key information like production date, batch number, and shelf life to effectively protect consumer rights. Simultaneously, the improvement of corporate quality systems, increased risk awareness, and the widespread adoption of automation are driving demand for product lifecycle traceability, refined channel management, and intelligent warehousing. In this context, inkjet printing technology is playing an increasingly important role. Leveraging its efficiency, flexibility, and cost-effectiveness in barcode generation and printing, this technology effectively helps companies enhance brand image, optimize market responsiveness, improve operational efficiency, and generate significant economic benefits. Its application is gradually expanding from traditional manufacturing to more emerging fields.

[0003] As a core consumable in inkjet printing technology, the market demand for inkjet printing ink continues to expand, and the industry's development potential is significant. However, most inkjet printer inks currently on the market still use methyl ethyl ketone (MEK) as the main solvent. Although MEK has advantages such as excellent solubility and rapid drying, it is classified as a Class III precursor chemical under my country's "Regulations on the Administration of Precursor Chemicals," requiring strict regulatory requirements during purchase and use, such as prior registration with the local public security bureau, increasing compliance and management costs for enterprises. In terms of safety, MEK is a toxic chemical; long-term exposure or improper handling can harm human health. Its flash point is only -9°C, classifying it as a low-flash-point flammable liquid, posing significant fire and explosion hazards. Therefore, the widespread use of MEK as the main solvent for inkjet printing ink has obvious limitations in terms of safety, compliance, and sustainability. Faced with increasing environmental and safety demands, especially in fields with extremely high material safety requirements such as food, pharmaceutical, and cosmetic packaging, developing a general-purpose environmentally friendly inkjet printing ink has become an urgent industry issue. Research in this direction not only aligns with regulatory trends and social responsibility but also possesses broad market application prospects. Summary of the Invention

[0004] To address the above problems, this invention provides an environmentally friendly inkjet ink and its preparation method. The inkjet ink of this invention is stable, fast-drying, and has good adhesion, and it completely eliminates the need for methyl ethyl ketone (MEK) as a solvent, making it more environmentally friendly.

[0005] The environmentally friendly inkjet printer of this invention comprises the following raw materials in parts by weight:

[0006] The formula contains 55-82 parts of organic solvent mixture, 5-26 parts of binder resin, 5-6 parts of colorant, 1 part of plasticizer, 5 parts of conductive additive, 1 part of leveling agent, and 1-2 parts of other additives. The total mass of the raw materials in the formula is 100 parts.

[0007] The organic solvent mixture is a single organic solvent A, or a mixture of organic solvent A, organic solvent B, and organic solvent C. Because methyl ethyl ketone (MEK) solvent is highly toxic, regulated, and causes significant environmental pollution, the non-ketone solvent constitutes the largest proportion of the system in this invention. Most importantly, this type of solvent is not classified as a precursor chemical, and it is less toxic than MEK, inexpensive, highly soluble, and has a moderate swelling effect on the substrate, making it an ideal substitute for MEK. Its boiling point is maintained between 50 and 100°C, ensuring that the ink dries in less than 10 seconds. This type of solvent has a milder odor, providing greater protection for those working in the coding industry. In the organic solvent mixture, by volume ratio, organic solvent B accounts for 0% to 1%, organic solvent C accounts for 0% to 5%, and the remainder is organic solvent A.

[0008] The organic solvent A is one or more of ethyl acetate, isopropyl acetate, n-propyl acetate, tert-butyl acetate, and n-butyl acetate. Organic solvent A is the main solvent of the ink of this invention, and its function is to dilute the ink, dissolve components, and ensure quick drying; it is one of the most important components in the ink.

[0009] The organic solvent B is selected from benzene-based and / or naphthalene-based organic solvents. Specifically, the organic solvent B is selected from one or more of p-xylene, m-xylene, ortho-xylene, toluene, decahydronaphthalene, and tetrahydronaphthalene, preferably p-xylene and / or decahydronaphthalene. Benzene-based and naphthalene-based solvents are mainly used to dissolve some of the incompletely dissolved benzene compounds and their homologues in the system.

[0010] The organic solvent C is an organic solvent with a boiling point of 150-250℃. Specifically, the organic solvent C is selected from one of N-methylpyrrolidone, N-ethylpyrrolidone, γ-butyrolactone, γ-valerolactone, and diethylene glycol butyl ether, preferably N-methylpyrrolidone. The use of small amounts of these highly polar organic solvents is mainly to dissolve undissolved polymers and disperse carbon black solids in the system, as well as small amounts of insoluble polymers that may be generated during ink formulation.

[0011] The binder resin is acrylic resin or any one or a mixture of two of acrylic resin, chlorinated wax resin, and chlorinated polypropylene resin. If it is two of them, the mixing ratio is not limited.

[0012] in:

[0013] The chlorinated polypropylene resin is CPP814HS, CPP841HS, CPP883S, CPP822S, CPP803MWS, or CPP863HS. This chlorinated polypropylene resin exhibits excellent adhesion to polypropylene and some polar materials, but its adhesion to polyethylene is poor. The resin can be dissolved in low-molecular-weight, non-polar solvents.

[0014] The acrylic resin is B-66, BR-103, BR-106, BR-83, BR-85, BR-113, BR-115, BR-116, MB-2660, MB-2952, MB-3015, or MB-7033. The acrylic resin comprises thermoplastic acrylic resin and hydroxyl acrylic resin, and possesses excellent solubility, flexibility, adhesion, and low viscosity.

[0015] The chlorowax resin is CP-430, CP-450, CP-710, TP-400M, TP-500A, or TP-500S. Binary and ternary chlorowax resins exhibit good solubility and stability, as well as excellent pigment dispersibility.

[0016] The colorant is a pigment or an oil-soluble dye.

[0017] The pigment is ariamar. TM B63、DENKA TM A mixture of one or more of conductive carbon black, Cabot VXC500 conductive carbon black, Ketjen black, carbon black 400R, and Microlith® Black CK in any proportion. The carbon black portion is conductive carbon black, which can greatly enhance the electrical conductivity of the system, but also requires a stronger dispersant for dispersion.

[0018] The oil-soluble dye is one or a mixture of two or more of Solvent Black 3, Solvent Black 4, Solvent Black 5, Solvent Black 7, Solvent Black 20, Solvent Black 22, Solvent Black 29, Solvent Black 34, Solvent Black 55, True Black 382, ​​and Y-28 in any proportion. The oil-soluble dye is completely soluble in organic solvents, the system is completely homogeneous, and there is no solid precipitate. Therefore, no dispersant is needed. The use of oil-soluble dyes also greatly enhances the stability and storability of the ink, and the printhead is less prone to clogging during printing.

[0019] The plasticizer is one or a mixture of two or more of the following in any proportion: triethyl citrate, diethyl phthalate, dioctyl phthalate, diisononyl phthalate, tricresyl phosphate, dioctyl adipate, and acetylated tributyl citrate. The plasticizer can improve the flexibility and extensibility of the ink layer, while also enhancing its adhesion, improving its low-temperature performance, and regulating its drying properties.

[0020] The conductive additive is one or more of the following in any proportion: dimethylamine hydrochloride, dibutylamine hydrochloride, tetramethylamine acetate, lithium hexafluorophosphate, lithium trifluoromethanesulfonate, tetrabutylammonium bromide, tetrabutylammonium chloride, and tetrabutylhexafluorophosphate. Different inkjet printer models have different conductivity requirements, but most machines require inks with a conductivity of 500-1500 μS / cm. Although some solvents and resins have some conductivity, their conductivity efficiency is far from sufficient. Therefore, a certain amount of conductive additive needs to be added to enhance the conductivity of the ink. However, many conductive additives have poor solubility; therefore, it is necessary to further adjust the amount of conductive additive used to achieve the best performance.

[0021] The leveling agent is BYK. TM 333, BYK TM 378, BYK TM 054-T, liquid paraffin, fluoropolymer FC TM -4430 is a mixture of one or more of these in any proportion. The leveling agent can help the ink layer eliminate surface defects, improve substrate wettability, promote flow and leveling, and improve gloss and vividness. At the same time, some leveling agents also have the function of reducing ink viscosity and preventing sticking.

[0022] The other adjuvants are Silquest A-177, Silquest A-1200, and Solsperse. TM 24000, Solsperse TM A mixture of one or more of the following: 36000, EFKA 5065, EFKA 3883, AFCONA 5065, KH-550, KH-608, KH-792, KH-560, KH-186, KH-151, KH-171, KH-172, KH-222, KH-221, KH-220, KH-223, KH-360, KH-350, KH-581, and EDTA, in any proportion. Other additives include various adhesion promoters, defoamers, dispersants, etc.

[0023] The preparation method of the environmentally friendly inkjet ink of this invention is as follows:

[0024] Dissolve the binder resin in a mixture of 50-60% organic solvent by weight, and stir at room temperature until the solution is transparent and homogeneous. Then add the conductive additive and continue stirring until completely dissolved to obtain a resin solution. In another container, dissolve the colorant in the remaining organic solvent mixture to obtain a colorant solution. Add the colorant solution to the above resin solution, continue stirring at room temperature, and add plasticizer, leveling agent and other additives. Stir thoroughly at room temperature to obtain the inkjet ink.

[0025] Among the many commonly used solvents for inks, ketone solvents have long been the main solvents used in inkjet printer inks due to their excellent performance in solubility and drying speed. Other organic solvents include alcohols, which are highly polar and hydrophilic, key components of aqueous systems, generally have low toxicity, are environmentally friendly, and biodegradable; however, they have weak solubility for non-polar substances, often requiring compounding, and their drying speed is relatively slow. Furthermore, lower alcohols (such as methanol) have specific toxicity. Benzene (aromatic hydrocarbons) have the core characteristic of strong solubility for non-polar / weakly polar substances due to their benzene ring structure, and are low in cost, leading to their widespread use. However, benzene solvent vapors are extremely toxic, some are highly carcinogenic, and cause significant environmental pollution. Esters offer a better balance between performance, safety, and environmental friendliness. They have wide applicability in solubility, adjustable evaporation rates, good leveling and film-forming properties, low toxicity, and a pleasant odor. They also have low photochemical activity and generate less ozone. Therefore, we have chosen to use some ester solvents as alternative solvents for methyl ethyl ketone (MEK).

[0026] Compared with existing technology formulations, the present invention has the following advantages:

[0027] 1. This invention completely abandons the methyl ethyl ketone (MEK) solvent used in traditional inkjet inks, and replaces MEK with a more environmentally friendly, less toxic solvent that is not classified as a precursor chemical, which greatly improves the safety of the ink and is more friendly to practitioners in the inkjet ink industry.

[0028] 2. This invention can adopt a carbon black-free solution, which greatly reduces the probability of printhead clogging caused by dispersed carbon black flying out and accumulating on the electrodes, and greatly improves the stability of ink operation in the machine.

[0029] 3. The configuration process of this invention is simple, the technical requirements for operators are not high, and the training cost is low. Detailed Implementation

[0030] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto. In the embodiments below, the total mass of the raw material formula of the coding ink is 100 parts.

[0031] The viscosity of the present invention is measured using an NDJ-8S digital rotary viscometer; the conductivity meter is a Huazhi Technology PD-T503F conductivity meter, and the measuring electrode is a CT01-A0014 conductivity electrode.

[0032] Example 1:

[0033] The raw material formula of the inkjet ink Ink-1 in this embodiment is as follows:

[0034]

[0035] Configuration process:

[0036] According to the above raw material ratio, weigh 5 parts of BR1113 acrylic resin and add them to 10 parts of ethyl acetate and 27 parts of tert-butyl acetate. Stir at room temperature until completely dissolved and homogeneous and transparent. Then add 5 parts of lithium trifluoromethanesulfonate and stir at room temperature until the conductive additive is completely dissolved. Then, in a separate container, add 5 parts of Solvent Black 34 to 45 parts of isopropyl acetate and stir at room temperature for 2 hours. Add the Solvent Black 34 solution to the above resin solution, and simultaneously add 1 part of diethyl phthalate, 1 part of liquid paraffin, and 1 part of KH-171. Continue stirring at room temperature for 12 hours to obtain the ink product.

[0037] Performance indicators: conductivity = 998 μS / cm, viscosity = 4.8 mPa·s.

[0038] Example 2:

[0039] In this embodiment, the raw material formula of the inkjet ink Ink-2 is as follows:

[0040]

[0041] Configuration process:

[0042] According to the above raw material ratio, weigh out 12 parts of CPP814HS chlorinated polypropylene resin and 14 parts of BR106 acrylic resin, and add them to 10 parts of isopropyl acetate and 25 parts of tert-butyl acetate. Stir at room temperature until completely dissolved and homogeneous. Then add 5 parts of lithium trifluoromethanesulfonate and stir at room temperature until the conductive additive is completely dissolved. Then, in a separate container, grind 5 parts of Cabot VXC500 conductive carbon black thoroughly, and add 1 part of Silquest A-177 dispersant to 10 parts of solvent A, 5 parts of N-methylpyrrolidone, and 20 parts of isopropyl acetate. Stir at room temperature for 2 hours until the carbon black particles are completely dispersed in the solvent. Add the carbon black solution to the above resin solution, and simultaneously add 1 part of dioctyl phthalate, 1 part of liquid paraffin, and 1 part of KH-570. Continue stirring at room temperature for 12 hours to obtain the ink product.

[0043] Performance parameters: conductivity = 1066 μS / cm, viscosity = 4.9 mPa·s.

[0044] Example 3:

[0045] In this embodiment, the raw material formula of the inkjet ink Ink-3 is as follows:

[0046]

[0047] Configuration process:

[0048] According to the above raw material ratio, weigh out 15 parts of BR-113 acrylic resin and 5 parts of CPP822S chlorinated polypropylene resin grease and add them to 5 parts of ethyl acetate and 30 parts of n-propyl acetate. Stir at room temperature until completely dissolved and homogeneous and transparent. Then add 5 parts of lithium trifluoromethanesulfonate and stir at room temperature until the conductive additive is completely dissolved. Then, in a separate container, add 6 parts of Solvent Black 20 to 30 parts of isopropyl acetate and 1 part of tetrahydronaphthalene and stir at room temperature for 2 hours. Add the solution of Solvent Black 34 to the above resin solution, and simultaneously add 1 part of diethyl phthalate, 1 part of liquid paraffin, and 1 part of KH-151. Continue stirring at room temperature for 2 hours to obtain the ink product.

[0049] Performance parameters: conductivity = 1360 μS / cm, viscosity = 4.3 mPa·s.

[0050] The environmentally friendly inks for inkjet printers prepared in Examples 1-3 were tested on an EC-1000 inkjet printer (ambient temperature: 25°C), and the adhesion of the inks was tested according to the following test methods:

[0051] Manual Peeling Method: Referring to GB / T 13217.7-2023 "Test Methods for Ink Adhesion", the adhesion of offset printing inks, gravure printing inks, flexographic printing inks, screen printing inks, inkjet printing inks, etc., is determined by the disc peeling method, manual peeling method, or cross-cut method. We use the manual peeling method as the second method to determine ink adhesion. The degree to which the ink film on various treated substrates containing different ink systems is adhered to or damaged by adhesive tape is expressed as the ink film integrity rate, indicating the ink adhesion. We use Scotch... ® The 600 high-grade transparent tape should be applied using the following steps:

[0052] 1. Using an EC-1000 inkjet printer, load test ink and print on various dry, flat, and clean test boards of different materials with dimensions of 3 mm × 50 mm × 200 mm. Then dry them in a ventilated place for 5 minutes.

[0053] 2. After the ink layer is completely dry and cured, apply the tape to the printed character surface and roll it back and forth three times with the tape roll to ensure that the tape adheres tightly to the ink layer. Then immediately peel off the tape smoothly at approximately 60° within 0.5 to 1.0 seconds.

[0054] 3. Observe the characters on the test section of the tape, count the number of ink dots that have fallen off and the number of ink dots remaining, and calculate using the following formula:

[0055] A = [A1 / (A1 + A2)]×100%

[0056] In the formula:

[0057] A: Ink adhesion;

[0058] A1: Number of ink dots remaining on the substrate after the tape is removed.

[0059] A2: Number of ink dots removed

[0060]

[0061] As can be seen from the data comparison in the table above, the inks described in the three examples all achieve good to excellent adhesion on various substrates, and their adhesion is comparable to that of commercial inks.

[0062] The above description is merely a general embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. An environmentally friendly inkjet printer, characterized in that... Its raw materials are composed of the following parts by mass: 55-82 parts of organic solvent mixture, 5-26 parts of binder resin, 5-6 parts of colorant, 1 part of plasticizer, 5 parts of conductive additive, 1 part of leveling agent, and 1-2 parts of other additives. The organic solvent mixture is a single organic solvent A, or a mixture of organic solvent A with one or more of organic solvents B and C; The organic solvent A is one or more of ethyl acetate, isopropyl acetate, n-propyl acetate, tert-butyl acetate, and n-butyl acetate; The organic solvent B is selected from benzene-based and / or naphthalene-based organic solvents; The organic solvent C is an organic solvent with a boiling point of 150~250℃.

2. The environmentally friendly inkjet ink according to claim 1, characterized in that: The organic solvent B is selected from one or more of p-xylene, m-xylene, phenoxyxylene, toluene, decahydronaphthalene, and tetrahydronaphthalene.

3. The environmentally friendly inkjet ink according to claim 1, characterized in that: The organic solvent C is selected from one of N-methylpyrrolidone, N-ethylpyrrolidone, γ-butyrolactone, γ-valerolactone, and diethylene glycol butyl ether.

4. The environmentally friendly inkjet ink according to claim 1, 2 or 3, characterized in that: In the organic solvent mixture, by volume ratio, organic solvent B accounts for 0%~1%, organic solvent C accounts for 0%~5%, and the remainder is organic solvent A.

5. The environmentally friendly inkjet printing ink according to claim 1, characterized in that: The binder resin is acrylic resin or any one or a mixture of two of acrylic resin, chlorinated wax resin, and chlorinated polypropylene resin.

6. The environmentally friendly inkjet ink according to claim 1, characterized in that: The colorant is a pigment or an oil-soluble dye.

7. The environmentally friendly inkjet ink according to claim 1, characterized in that: The plasticizer is one or more of the following in any proportion: triethyl citrate, diethyl phthalate, dioctyl phthalate, diisononyl phthalate, tricresyl phosphate, dioctyl adipate, and acetylated tributyl citrate.

8. The environmentally friendly inkjet ink according to claim 1, characterized in that: The conductive additive is one or more of the following in any proportion: dimethylamine hydrochloride, dibutylamine hydrochloride, tetramethylamine acetate, lithium hexafluorophosphate, lithium trifluoromethanesulfonate, tetrabutylammonium bromide, tetrabutylammonium chloride, and tetrabutylhexafluorophosphate.

9. The environmentally friendly inkjet ink according to claim 1, characterized in that: The leveling agent is BYK. TM 333, BYK TM 378, BYK TM 054-T, liquid paraffin, fluoropolymer FC TM -4430 is a mixture of one or more of these in any proportion.

10. A method for preparing the environmentally friendly inkjet ink according to any one of claims 1-9, characterized in that... Includes the following steps: Dissolve the binder resin in a mixture of organic solvents and stir at room temperature until the solution is transparent and homogeneous. Then add the conductive additive and continue stirring until completely dissolved to obtain a resin solution. In another container, dissolve the colorant in the remaining mixture of organic solvents to obtain a colorant solution. Add the colorant solution to the above resin solution, continue stirring at room temperature, and add plasticizer, leveling agent and other additives. Stir thoroughly at room temperature to obtain the inkjet ink.

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