what is UV ink and its development history?
Date: Aug 04 2024 From: Star Color
First, what is UV ink and its development historyUV ink definition:
UV ink, the full name of ultraviolet curing ink, is a special ink that can quickly cure into a film under ultraviolet (UV) irradiation. It is unique in that its drying process does not rely on traditional solvent volatilization or thermal curing methods, but through the chemical reaction triggered by ultraviolet radiation to achieve rapid curing of the ink.
Specifically, the composition of UV inks mainly includes polymeric prepolymers, photoinitiators, photosensitive monomers (also known as active diluents), coloring pigments, and fillers and additives that may be added. Among them, the polymeric prepolymer is the main film forming substance of ink, which determines the basic properties of ink film after curing. The photoinitiator is the "trigger" of the whole curing process, which produces free radicals after absorbing UV energy, and then triggers the cross-linking polymerization of the polymeric prepolymer and the photosensitive monomer. The photosensitive monomer, as the reaction medium, participates in the curing process and regulates the viscosity of the ink. Coloring pigments give the ink color, but also affect the ink's hiding power, light resistance, heat resistance and other properties; Fillers and auxiliaries are used to improve the fluidity, stability and other physical properties of the ink.
During the curing process of UV ink, when the ink is exposed to ultraviolet light, the photoinitiator rapidly absorbs light energy and transforms into free radicals. These free radicals then initiate a chain polymerization reaction between the polymeric prepolymer and the photosensitive monomer, forming a highly cross-linked three-dimensional network structure. This reaction process is very rapid, usually only a few seconds to a few minutes to complete, so that the rapid curing of the ink.
The development of UV ink:
- 1960s: Scientists first discovered UV-curable ink, creating the development of the UV ink industry.
- 1970s: UV ink began to be widely used in the printing industry, especially in the packaging industry and printed circuit board industry.
- In the 1980s, the UV ink industry entered a stage of rapid development, the market continued to expand, and the application field gradually expanded.
- 1990s: The production technology of UV ink has been a major breakthrough, product quality has been continuously improved, and market competitiveness has been continuously enhanced.
- Since the beginning of the 21st century: the UV ink industry continues to innovate, product quality and technical level continue to improve, and the application field has been further expanded to electronics, packaging, plastics, glass, ceramics and other industries. UV ink has become a more mature ink technology and has been widely used in the world.
Second, the principle of UV inkThe principle of UV ink is that the photochemical reaction of the ink is caused by the radiation of the ultraviolet light source to the ink, so as to achieve the purpose of ink curing. There are two main chemical reactions in the drying process:
Photochemical reaction: When UV ink is exposed to ultraviolet light, the photopolymerization initiator (photoinitiator) in the ink absorbs the ultraviolet light energy and transitions from the ground state to the excited state to form free radicals or ions. This step is the starting point of the curing process and the key to the whole reaction.
Chain reaction: The free radicals generated by the photochemical reaction are highly active, and they can trigger the chain polymerization reaction of unsaturated polyfunctional group prepolymers, multifunctional crosslinking agents, active diluents, etc., in UV ink. In this process, the free radicals constantly react with the surrounding molecules to form new free radicals, forming a growing polymer chain. These chain molecules are cross-linked to form a three-dimensional network structure, so as to realize the curing of the ink.
With the progress of the chain reaction, the polymer compounds in the UV ink are gradually cross-linked into a network structure to form a strong solidified film. This film has the advantages of good adhesion, wear resistance, chemical resistance and color brightness.
It should be noted that the curing process of UV ink is affected by a variety of factors, including the wavelength, intensity, irradiation time and the formula of the ink. Among them, the wavelength of ultraviolet light has a significant effect on the curing effect. In general, UV inks are most sensitive to near-ultraviolet light with a wavelength of 300 ~ 400nm, especially in the wavelength range of 350-420nm, where the pigment of the ink has the greatest transmittability, so the curing effect is the best.
Third, the formula of UV inkUV inks are mainly composed of the following key components: polymeric prepolymers, photoinitiators, photosensitive monomers (also known as active diluents), coloring pigments, and possibly added fillers and a variety of additives.
3.1. Cohesive prepolymers
Definition and function: The cohesive prepolymer is the most basic formulation component of UV ink, and it is also a film forming substance. It plays a decisive role in the performance of solidified ink film, such as hardness, friction resistance, adhesion, light resistance, chemical resistance and water resistance.
Type: The polymeric prepolymers mainly include methyl acrylyl, unsaturated polyester resin, polyether acrylic resin and so on. These resins contain unsaturated double bonds in their internal chemical structure, which is the main component of forming cured films.
Classification basis: The aggregate prepolymer is usually classified according to the skeleton structure, and the different skeleton structure determines the difference in its performance after curing.
3.2. Photoinitiator
Definition and function: Photoinitiator is a key component in UV inks, its role is to absorb ultraviolet light energy, produce free radicals or ions, thereby triggering polymerization. The choice of photoinitiator directly affects the curing speed and curing effect of ink.
Type: Photoinitiators are divided into two types: hydrogen capture type and cracking type. Hydrogen-grabbing photoinitiators extract hydrogen atoms from different alkyl groups and aryl groups and stimulate them to become excited complexes. Lytic photoinitiators act by stimulating direct decomposition into free radicals.
Selection principle: When selecting a photoinitiator, it is necessary to consider the factors of high absorption efficiency, good relative stability and low cost in the UV range.
3.3. Photosensitive monomer (active thinner)
Definition and function: Photosensitive monomer, also known as active diluent, is a functional monomer. It not only provides viscosity for the UV ink, but also participates in the curing reaction, increases the curing speed, and becomes part of the curing film.
Type: Photosensitive monomers mainly include monofunctional compounds and bifunctional or multifunctional compounds. The former is like styrene, and the latter is like acrylates of polyols.
Selection principle: When selecting photosensitive monomers, it is necessary to follow the principles of low viscosity, good dilution effect, fast curing and leaving no odor in the coating.
3.4. Coloring pigments
Definition and function: Coloring pigment is an essential component of UV ink, it gives the ink color, and affects the ink's hiding power, light resistance, heat resistance and other properties.
Type: UV ink commonly used color pigments are benzidine yellow, Hansha yellow, phthalocyanine blue, phthalocyanine green, permanent red, big red powder; The achromatic pigments are titanium dioxide, high pigment carbon black and so on.
Influence: The addition of pigments will change the rheological properties of the ink and affect the gloss of the printing film. At the same time, the absorption, reflection or scattering of UV light by the pigment will also reduce the curing and drying speed of the ink.
3.5. Fillers and additives
Fillers: fillers are mainly used in ink to increase the solid content, improve the rheological properties of ink, and reduce the price of ink. Commonly used fillers are calcium carbonate, aluminum hydroxide, silicon dioxide and so on. However, the addition of fillers may also hinder the absorption of UV light by the ink and reduce the drying rate of the ink.
Additives: In order to improve the printability and quality of UV ink, it is also necessary to add a variety of additives. These additives include anti-polymerization agents (to prevent ink cross-linking during storage), defoamer (to eliminate ink bubbles during manufacturing and use), leveling agents (to improve the leveling of ink layers) and so on.
Fourth, classification of UV inkUV ink classification methods are diverse, here we mainly discuss the classification according to printing technology, UV ink according to printing technology classification, can be mainly divided into the following types, each type has its specific application scenarios and advantages. Here is a detailed explanation of these types:
4.1. UV offset ink
Application scenario: UV offset printing ink is widely used in books, magazines, packaging and other printed matter printing. It is suitable for high-speed continuous printing, which can maintain bright color and stable printing quality.
Features:
Fast curing speed: Through ultraviolet light irradiation, UV offset printing ink can be cured quickly in a short time, improving production efficiency.
Bright color: The ink is full of color and can show high definition printing effect.
Environmental protection and energy saving: no heating is required during the curing process, and almost no volatile organic compounds (VOCs) are produced, which meets environmental requirements.
4.2. UV screen printing ink
Application scenario: UV screen printing ink is mainly used for screen printing, suitable for printing small area, raised patterns, such as glass bottles, ceramics and so on.
Features:
Strong adhesion: UV screen printing ink can be firmly attached to the surface of the substrate, not easy to fall off.
Good toughness: The printed pattern has good toughness and can adapt to various shapes and surfaces of the substrate.
Fast curing: Also through ultraviolet irradiation to achieve fast curing.
4.3. UV flexographic ink
Application scenario: UV flexo printing ink is suitable for printing on absorbent/non-absorbent substrate surface, flat/rough substrate surface, thin/thick substrate surface. It has been widely used in packaging printing fields such as flexible packaging, cartons, labels and corrugated boxes.
Features:
Good printability: can adapt to the printing needs of different materials and surfaces.
Low cost: Compared with other printing technologies, UV flexographic inks have certain advantages in cost.
Energy saving and environmental protection: The curing process does not require a lot of energy, and meets the environmental requirements.
4.4. UV inkjet ink
Application scenario: UV inkjet ink is mainly used for inkjet printers, suitable for various digital printing needs, such as personalized customization, short printing and so on.
Features:
High precision: inkjet technology can achieve high precision printing effect.
Fast curing: Through ultraviolet irradiation, the ink can be quickly cured and improve production efficiency.
Wide range of application: suitable for a variety of substrate materials, including paper, plastic, metal, etc.
4.5. UV gravure ink
Application scenario: UV gravure ink is suitable for gravure printing, mainly used in plastic film, paper, plastic bags and other materials printing.
Features:
Strong adhesion: the ink can be firmly attached to the substrate surface, not easy to fall off.
Good wear resistance: The printed pattern has good wear resistance and can adapt to various use scenarios.
High resolution: gravure printing technology can achieve high resolution printing effect, so that the pattern is more delicate.
Five, the development and prospects of UV inkWith the growth of the global economy and the increase in consumer spending, the demand for UV ink market continues to grow. According to the report, worldwide, the UV ink market shows a growth trend, the global market size in 2023 reached 20.629 billion US dollars, is expected to reach 40.581 billion US dollars by 2029.
The application field of UV ink is constantly expanding, covering many industries such as printing, packaging, advertising, and electronic products. Especially in the packaging and advertising industries, UV inks are widely welcomed for their high gloss, good adhesion and environmental performance.
With the increasing demand for personalized customization, UV printing technology can achieve highly personalized design and printing to meet the customization needs of different industries and customers, and further promote the development of UV ink market.
With the continuous progress of science and technology, the formula and production process of UV ink are constantly innovative and improved. The development of new monomers, resins and additives enables UV inks to have better performance, such as faster curing speed, higher wear and chemical resistance, and better printing results.
The popularity of digital printing technology has also promoted the development of UV digital printing systems, which has further improved the printing speed and accuracy of UV inks.
With the increasing awareness of environmental protection, the requirements of the UV ink market for environmental performance are also increasing. New UV ink products often have low volatile organic compound (VOCs) emissions, low energy consumption and low pollution to meet environmental regulations and consumer demand for green products.
UV ink industry is in a stage of rapid development, technical barriers are high, but the profit space is large. With the growth of market demand and continuous progress of technology, the industry will usher in more development opportunities.
Especially in the fields of digital printing, personalized customization and environmental protection inks, UV inks will show greater development potential.
Huizhou StarColor Technology Co., Ltd. is a company specializing in the development and production of water-based ink, flexographic, gravure and UV environmental protection ink. With excellent technology research and development capabilities and forward-looking market insight, the company has always stood at the forefront of the industry to provide high-quality ink products for the printing industry.
StarColor has a professional R & D team and advanced production equipment, committed to the development and innovation of UV ink technology. The company continues to introduce advanced technology and management experience at home and abroad to improve product performance and quality to meet the changing needs of the market.
With the increasingly strict environmental regulations and the growing market demand for high-quality printed matter, the UV ink market has a broad prospect. StarColor will continue to adhere to the development concept of "innovation, environmental protection and efficiency", increase research and development investment, improve product performance and quality, and provide customers with better quality ink products and services. At the same time, the company will also actively expand domestic and foreign markets to promote the green and sustainable development of UV ink industry.
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