Author: Lei Limeng Technical Exchange Hotline: 13928864478
Puhler Group, Germany, Sales Director, Greater China, Guangzhou Peller Machinery Equipment Co., Ltd.
With the rapid development of digital technology, inkjet printers have become the main choice for office and family because of their low price and high printing capacity. The increasing market of inkjet printers has promoted the rapid growth of the application of inkjet inks in the past few years, which is mainly reflected in the improvement of the technical capabilities of inkjet systems in various fields of inkjet inkjet applications, the surprise of faster and higher resolution inkjet equipment and the commercialized products of new inkjet inkjet and printing media. Human growth. There are three parts in inkjet printing technology: inkjet printer, printing ink and inkjet printing receiving medium. Ink-jet ink affects the color brightness, water resistance, light resistance and preservation characteristics of inkjet printing images. Ink-jet ink is an important element of digital image technology output, and plays a vital role in the quality of hard copy of digital image output. Here is a brief introduction to inkjet ink.
Classification and composition of inkjet ink
Ink-jet ink can be generally divided into two types: pigmented ink and dye-based ink. The dyes of dye-based ink are completely dissolved or dispersed in the medium, while the pigment particles of pigmented ink are floating or suspended in the medium.
Contrast the properties of pigmented and dyed inks:
1. This phenomenon occurs when black dye ink and color dye ink are used simultaneously (left image)
Show).
(1) Black handwriting diffuses to yellow area
(2) The edges of printed text and lines are not smooth.
Printing with black pigmented ink and color dyed ink has smooth and sharp edges (shown in the right).
This is because dye inks are easily influenced by the type and quality of paper used because of their own characteristics, and paper fibers absorb dye inks to a certain extent. If non-glossy paper with high fibre content is used for printing, the edge of the handwriting will have a hairy edge. Pigment ink contains pigment particles suspended in water, which are small enough to pass through fine nozzles, but too large to disperse on paper, so the pigment particles only stay on the surface of paper fibers.
(1) Pigment ink has better light resistance than dye ink.
(2) The water resistance of pigmented ink is much better than that of dye ink.
(3) The disadvantage of pigmented ink is that pigments can be erased from paper, so it is dirty-resistant and can not be used in official documents. Pigmented ink is not suitable for slide presently because it is not easy to dry and has insufficient adhesion on the negative.
Generally, any ink consists of the following components: solvent (water-borne, solvent-based or oily), dye (liquid, powder), or pigment, additive-mdash; & mdash; mainly the following:
(1) Moisturizer: prevent ink from drying out before printing;
(2) Preservatives: to prevent the growth of bacteria and fungi;
(3) Additives for controlling pH value;
(4) Additives for adjusting viscosity;
(5) Additives that give ink special properties are trade secrets.
Requirements for the quality of water required for the production of high-quality inkjet ink:
1. Water quality requirements are extremely pure: conductivity & lt; 0.2 & mu; S (micro Siemens), which shows that water quality is better than automobile battery water or even better than medical distilled water;
2. Low hardness;
3. The requirement of pH-value is neutral (approximately 7);
4. Special water purification equipment such as reverse osmosis and ion exchange should be used. Step 1: reverse osmosis, water treatment capacity: 400L purified water/h@10μ step 2: ion exchange, water treatment capacity 400L purified water/h@0.1μ and step S, besides high purity water quality, the purity of solvent used should be more than 99.5%.
II. Main Properties of Inkjet Ink
The main properties of inkjet ink are: color (black, cyan, yellow, magenta...), drying time, light density, brightness of each color, color of a set of ink (ink for the same color cartridge) and light resistance.
1. Color metric, gamut of ink
If the tone of compatible ink is different from that of original ink, most people (end users) will not recognize the difference in black ink. If printing only uses one independent color (chart, color text title, line, etc.), the sensitivity will not be very high. If printing pictures and photographs of multiple colors, only one will be. The color difference of the ink will affect the effect of the whole image.
2. Optical density
Optical density indicates the blackness of printed text. As shown in the following figure, the development trend of optical density of original HP cartridge shows that the requirement of printing quality of terminal customers is constantly improving.
In addition, pigmented inks have higher optical density than dye inks, so pigmented inks print text with better blackness and better effect.
3. Light Tolerance
Light resistance-mdash, also known as ultraviolet resistance, is one of the characteristics of ink, which is affected by many factors, such as:
(1) Exposure time of prints in sunlight
(2) Chromatography and Light Intensity
(3) Printing media used
(4) Other factors affecting the surrounding environment
The fading degree of dye-based ink depends on the basic color and the anti-fading ingredients in its formulation, while the pigment-based ink does not show obvious fading in the long term. Different colors of dyes have different light resistance. Generally speaking, most blue and blue dyes are not easy to fade, followed by yellow dyes, and red and magenta dyes are the least light-resistant. It can be seen that the fading of printing products is related to the change of color when dye ink is used. The fading of printing products becomes more blue.
3. Physical and Chemical Parameters of Inkjet Ink
Physical and chemical parameters affect the rheological properties of ink and its function in cartridges. Chromaticity represents the color quality of printing output and forms visual effect. The rheological properties and color of ink determine the quality of inkjet printing. Physical and chemical parameters of ink mainly include surface tension, viscosity, PH value, conductivity, specific gravity, chroma and so on.
　In order to ensure the high quality and stability of the product, the quality of each batch of ink should be tested by a precise instrument, and the Batch Certificate of the product should be recorded in detail. The effects of physical and chemical properties of ink on printing quality are described in detail below.
1. Surface tension (interfacial tension)
The compressive force acting perpendicularly on a unit length along a liquid surface is called surface tension.
Surface tension is very important for the size of ink droplets in printer cartridges and nozzles and the flow of ink. Liquid with low surface tension has better wettability than liquid with high surface tension. The surface tension of water is about 72 mN/m. The surface tension of water-based dye inks is 26-40 mN/m. Some black inks can reach 50-55 mN/m or higher (tested at 20 ~C). The surface tension of ink is closely related to the sponge in the cartridge. In order to ensure the smooth flow of ink, the surface tension of ink and the physical characteristics of sponge in the cartridge must be coordinated. Normally, sponges should not be replaced at will before performance testing.
2. Viscosity
All liquids have certain resistance to shape change. The frictional properties of this liquid are called viscosities.
Viscosity characterizes the flow characteristics of ink. The viscosity of dilute liquids is low, while that of concentrated, slow-flowing liquids is high. How much ink viscosity is required depends on the printer/printer nozzle/cartridge requirements, as well as the surface tension and printing quality requirements.
Surface tension and viscosity both affect the ink flow in ink cartridges during printing, especially those with sponges inside, and also affect the quality of printing, including the penetration of ink on different paper. Every different printer or printing nozzle or even printing technology needs ink with specific surface tension and viscosity, so all ink must be developed and prepared according to specific requirements, which is why there is no universal ink.
3. pH Value
Ink usually has a pH range of 4.5-mdash; 9. If the pH value is too low (acidic), the ink will corrode the cartridge; on the contrary, if the pH value is too high (alkaline), it will produce additional salt, which will reduce the service life (corrosion) of the cartridge and improve the conductivity. Usually, the ink used for filling should have the same pH range as the original ink, so it is possible to be compatible with the residual original ink inside the cartridge (if there is no cleaning inside the cartridge). Moreover, in order to ensure good stability of the ink, the PH value of the ink must be equal to that of the dye.
4. Conductivity
Conductivity is the reciprocal of resistance, and its unit is Siemens, usually micro Siemens & mu; S and millisiemens mS. For electrolyte solution, two parallel electrodes with an area of 1 m2 are placed in the electrolyte solution. When the distance between the two electrodes is 1 m, the conductivity of the solution is the conductivity.
It indicates the concentration of ions in the ink. Usually the conductivity of public water is 600-1800 & mu; S, which depends on the concentration of inorganic salts (sodium, potassium, magnesium, etc.). Too much inorganic salt in ink can easily crystallize at the nozzle and cause damage to cartridges. Therefore, the conductivity of deionized water used in ink making is 0.2-10μ S. But ink has a higher conductivity because the dyes (organic salts) in the ink composition have ionic properties. But the ionicity of dyes does not damage cartridges as inorganic salts do.
5. Specific gravity
The specific gravity is determined by the composition of the ink, usually between 1.0 and 1.08g/cm3. Density is very important for calculating the surface tension of ink, but it hardly affects the function of ink itself.
6. Chromaticity
Lab color space is the most common color system for measuring ink color and comparing different color differences. In three coordinates, one axis from left to right - A - +a (green to red), the other from back to front + B & mdash; & mdash; - B (yellow to blue), and the third from top to bottom is called L axis (for brightness). Each point in the coordinate system represents a color. The instrument is a photometer, even if it is very close to the difference between two colors (the difference between two colors can not be recognized by the naked eye).
However, because of the different types of paper, the color will also vary. In order to ensure that ILT ink has the closest color performance to the original ink, ILT will select the same paper as the original one in the chromaticity test. For example, in the detection of EPSON compatible ink, ILT will use EPSON-specific printing paper, while in the detection of HP-compatible ink, it will choose HP-specific printing paper.
With the rapid development of digital technology, inkjet printers have become the main choice for office and family because of their low price and high printing capacity. The increasing market of inkjet printers has promoted the rapid growth of the application of inkjet inks in the past few years, which is mainly reflected in the improvement of the technical capabilities of inkjet systems in various fields of inkjet inkjet applications, the surprise of faster and higher resolution inkjet equipment and the commercialized products of new inkjet inkjet and printing media. Human growth. There are three parts in inkjet printing technology: inkjet printer, printing ink and inkjet printing receiving medium. Ink-jet ink affects the color brightness, water resistance, light resistance and preservation characteristics of inkjet printing images. Ink-jet ink is an important element of digital image technology output, and plays a vital role in the quality of hard copy of digital image output. Here is a brief introduction to inkjet ink.
IV. Manufacturing Method and Testing of Inkjet Ink
The most important way to prepare inkjet ink is to select suitable solvents (or dispersants) and colorants (dyes or pigments), and then add certain additives according to different types of ink.
1. Preparation of dye-based ink (water-based ink)
First, the dyes are dissolved in deionized water, then water soluble and appropriate additives are added, stirred, stationary and filtered.
Process:
(1) Take deionized water of 89-90 degrees, add direct black dye and stir for 1 hour.
(2) After adding polyols, heterocyclic compounds, aromatic carboxylic acids and sodium chlorophenol in turn according to the prescription dosage, stirMix for 1 hour.
(3) Stay for 4 days.
2. Preparation of Pigment Ink
Example 1: In order to obtain better ink, disperse dyes and pigments are best made of ultrafine particles (nano-scale), which requires the use of grinding and grinding steps, such as ball milling. The process may be:
(1) Mixing the components and adding a certain amount of water to adjust the viscosity necessary for grinding;
(2) In conventional grinding machines (such as Pyler Ultrafine Nano-Bead Mill), the grinding cycle lasts until the required fineness is reached.
(3) Transfer to the mixer and add water until the required amount of water is reached.
(4) Filtration.
Example 2: Epson's Ink with Pigment as Colorant:
Carbon black 15 g, styrene acrylic copolymer 3 g, triethanolamine 7 g, water 75 G.
Preparation process:
(1) Mixing carbon black with dispersant in dispersing medium;
(2) When the liquid pressure is greater than 1-times and 107 kg/m.sec2, the dispersed phase enters the dispersed chamber through a small hole, and the pigment particles are crushed under low pressure of the surrounding liquid.
(3) Centrifugal filtration resulted in uniform dispersion of pigment particles.
(4) Dilute the dispersant to the required concentration.
Note: The above is just an example, not necessarily accurate.
3. Nanotechnology and Ink
Dye components are easy to crystallize, which results in blockage of ink jet head and irreparable printer failure.
By means of nano-ultrafine technology, high-pigmented carbon black is used as the main component, chemical reagent as the auxiliary component and water as the solvent to form a stable colloidal dispersion system-sol. The average particle size of ink is 66 nanometers. The characteristics of the ink are as follows:
(1) No plugging;
(2) Non-fading;
(3) Indium-free water;
(4) Strong weather resistance: after freezing at minus 20 degrees, the ink will recover, and the ink performance will remain unchanged.
(5) Wide adaptability.
The working principle of nanotechnology is that the processed products are mixed into suspension and loaded by high pressure pump (working pressure is 100 kg-mdash; & mdash; 1500 kg) into various channels composed of two streams at high speed or three artificial single crystal diamond sheets with diameter of 8 cm, which collide with each other. After shunt outflow. Because of the high velocity of the liquid (700 kg pressure, 300 M/S per hour), the shock wave of 450 MPa is generated when the fluid collides with each other, which stimulates the diamond wafer to produce high frequency and super-strong ultrasonic field (biochemical theory), and makes the processed particles in the suspension instantaneously comminute, disperse, emulsify and synthesize.
5. Deep Exploration of Inkjet Ink
In the industry, the application of inkjet printer ink has been very popular, whether imported compatible inks or domestic inks, in the production, inspection and application of a very wide range, especially high-quality and low-cost domestic inks in all aspects also tend to mature. However, due to the absence of national standards with unified guidance, the use of products with different good and bad causes great inconvenience to users. Combining with the relevant production practice experience, this paper discusses the ink from the aspects of manufacturing, testing and application, and summarizes the solution of inkjet hydrolysis. It is hoped that this solution will have a certain reference significance for consumables manufacturers and users, in order to gain the role of special reference.
1. Production Control Solutions
(1) Research and development equipment
Pyler ultrafine nano-grinding machine, quantum analyzer, spectrophotometer, chromatograph, ultrasonic detector, surface tensiometer, viscometer, conductivity meter, aging testing machine, etc.
(2) Manufacturing Control
Purification of colorants: Screening of colorants, desalting, refining and purification.
Purification equipment: ultrafine filtration, ion exchange, electrodialysis and reverse osmosis filtration of water.
Ink filtration: vacuum dust-free nanofiltration, simulated flocculation sedimentation filtration.
Ink water treatment: ultrasonic defoaming, aging test.
(3) Quality Control
ISO 9001 International Quality System Control, etc.
2. Quality Inspection Solutions
(1) Ink test pH value, viscosity, surface tension, conductivity, material compatibility (plastic compatibility, sponge compatibility, binder compatibility), ink compatibility, volatility, stability (color stability, weather resistance), non-toxicity, etc.
(2) Printing test: color density, fluidity, fast drying, permeability, resolution, color transition, color stability (sunproof, anti-ultraviolet, waterproof, friction stability), etc.
3. Solution of Ink Application
(1) Matching and application solutions for consumables manufacturers
(2) User Application Solutions
Focus on inks inspection and application; Ink application solutions: ink hydrolysis solutions for cartridge production.
Requirements for ink in cartridge production:
A Ink compatibility with various cartridge materials (plastic shell, sponge, silica gel sealing ring, filter screen, spring, steel ball, etc.).
At present, most of the sponges used in cartridges are polyurethane, which requires that the chemical composition of the ink do not react with polyurethane. The aging test can be used to verify whether there are chemical changes over a long period of time. When stainless steel materials such as filter screen are immersed in ink, it can be judged by controlling the conductivity value of ink. If the conductivity is too high, salt corrosion or electrochemical reaction may occur to stainless steel, resulting in corrosion to stainless steel, which indicates that ink has potential harmfulness. Whether the solvents and additives in ink react to the components of plastic shell (including PP, PS, ABS, etc.) and penetrate the welding wire. Similar aging experiments were conducted on other materials to verify the compatibility of ink and materials. The aging experimental conditions should simulate all kinds of weather conditions (such as high and low temperature, humidity, pressure, light, etc.).
B Ink Printing Fluency (Sponge, Kapok Core)
There are four main factors affecting ink printing fluency: compatibility and matching of ink with sponge and kapok core, which can be changed by adjusting ink viscosity or surface tension, or choosing sponge and kapok core suitable for ink; in addition, it may be ink.The stability of the ink is not good, the flocculation precipitation of the ink produces, blocking the filter screen or nozzle, resulting in poor printing. This is because other soluble impurities in the ink produce electrochemical reaction, forming condensation, or the ink solvent volatility is strong, dyes or pigments crystallization precipitation caused by printing blockage; the other two cases are with ink cartridges. The structure of the nozzle, the ink storage chamber and the structure of the nozzle are related to the formation of bubbles, resulting in poor ink setting (e.g. no sponge cartridge), and the aging degree of the printing head itself. This is not to be reported for the time being.
VI. Application and Prospect of Inkjet Ink
Ink-jet ink includes water-based ink-jet mode, solvent-based ink-jet and self-curing inkjet ink, which are more and more widely used, and the field is wider and wider over the past month, and there are also special types of ink developed in many applications. Inkjet printing will be one of the fastest growing areas in the future. The advantages of inkjet technology in printing field are firstly the operability and low cost for short-term production and printing with variable data. Secondly, inkjet printing enables non-contact printing to be carried out on various materials, such as different kinds of paper, cardboard and non-absorptive materials such as plastics. The third production advantage is that plate-making is not needed, the production process is simplified and the cost is reduced. In addition, ink-jet printing has a wide selectivity for ink, such as water-based ink-jet, solvent-based ink and so on. Industry insiders predict that by 2010, digital printing will account for 20% of all printing, of which inkjet printing will account for a large share.
The combination of inkjet printing and traditional printing technology makes possible the application of new inkjet technology for new uses such as photographs, ceramic tile printing, short-term textiles, labels, decorative coatings and electrical appliances manufacturing. Wide-width inkjet imaging is one of the fastest growing inkjet technologies, with an expected growth of 10-20%. The new field of inkjet ink application is mainly wide-width inkjet printing. Wide-width inkjet printing is being widely used in various new applications, so the growth of inkjet ink in the wide-width printing market is several times the growth of inkjet ink in other fields.
The application of flat panel technology and self-curing inkjet technology provides new possibilities for the expansion of inkjet technology applications. Environmental protection, durability and reliability of printing on various substrates, including the ability to print on hard materials, make inkjet developers see new market opportunities.