Keywords: UV ink UV light source matching the promotion of the use of UV ink, has greatly solved the thermal printing paper and other special printing materials in the printing of high-speed printing problems. However, due to the different characteristics of the material itself, the phenomenon of poor drying was still found in the production of UV inks. why? This is because the matching of the UV ink with the UV light source is ignored.
First, UV ink 1. Composition UV ink is under the irradiation of UV light, cross-linked polymerization occurs, instantly cured film forming ink. It is mainly composed of a photopolymerizable prepolymer, a photosensitive monomer, a photopolymerization initiator, an organic pigment, and an additive. Among them, the photopolymerization initiator is the most important component of the entire UV ink and is the beginning of photopolymerization reaction. Commonly used photopolymerization initiators include aromatic ketones and esteroin ethers.
2. Features (1) Instant drying at low temperature;
(2) Good gloss and high adhesion;
(3) No solvent, good stability;
(4) strong printability, to meet the needs of a variety of substrates;
(5) Save energy and improve efficiency;
(6) Small environmental pollution.
3. Curing Mechanism Under the irradiation of UV light, the photopolymerization initiator in the UV ink absorbs photons of a certain wavelength, excites excited states, and forms free radicals or ions. Then, a polymer such as a polymerizable prepolymer and a photosensitive monomer is brought into an excited state by energy transfer between molecules, and a charge transfer complex is produced. These complexes continuously crosslink and polymerize to form a film. Its photochemical reaction history can be expressed as:
Among them, D is a photopolymerization initiator, and A is a photopolymerizable prepolymer and a photosensitive monomer. In the course of UV ink curing, the photopolymerization initiator is excited to the excited state, which is a crucial step, and it determines the efficiency of the entire photochemical reaction.
![]()
It means that the photopolymerization initiator under the irradiation of UV light has a change in the distribution of electrons in the molecule, and the molecule is excited into an excited state to generate radicals. As we all know, due to the different molecular motion states, the molecule contains many kinds of energy. Among them, electron energy is the main body. Its energy distribution is not continuous, but is similar to the step-like energy level distribution. The change of the molecular motion state is that the molecule absorbs radiation of a certain wavelength and excites from the low energy level to the high energy level to form an excited state. According to the law of photochemical equivalence, the light absorption of a substance is performed in units of photons, and the molecule can only absorb one photon at the same instant; and only when the energy of the photon is exactly equal to the difference between the two energy levels of the molecule can it be absorbed by the molecule. which is:
E2-E1=hÏ…...............(1)
In formula (1): E1 is the energy level before the molecule absorbs light energy, E2 is the energy level reached after the molecule absorbs light energy, h is the Plank constant, and Ï… is the frequency of the absorbed light. By formula (1) know:
Ï…=(E2-E1)/h
For A, B two different molecules, there are:
Ï…A=(EA2-EA1)/h
Ï…B=(EB2-EB1)/h
Different molecules: EA2-EA1≠EB2-EB1:
υA≠υB
That is, the two molecules A and B absorb light of two different wavelengths (λ=C/υ, C is the speed of light), that is, the material molecules selectively absorb light. Different UV inks have different photopolymerization initiators. The photons they choose to absorb are also different. Therefore, each UV ink is only sensitive to light of a specific wavelength in the spectrum of the UV light source.
Moreover, the photochemical reaction is related to the number of effective photons. The more effective photons, the greater the chance that the photopolymerization initiator will absorb such photons and the faster the photochemical reaction rate. Assuming that the total energy of a UV light source radiates light is E, and the energy of light with a frequency of Ï… is EÏ…, and the ratio of EÏ… in E is k, then:
EÏ…=kE
In formula E2-E1=hυ, hυ represents the energy of a photon, so the number of photons of frequency 为 is N=Eυ/hυ=kE/hυ
Visible: N is proportional to k, E. That is, the number of photons is determined by the total energy of the radiated light of the UV light source and the distribution of the light energy of each wavelength.
From the above, it can be known that the UV ink selectively absorbs photons of UV light, and its drying is affected by the total energy of the light irradiated by the UV light source and the distribution of light energy of different wavelengths.
Second, UV light source 1. Construction UV light source is a device that emits UV light in a UV curing system. Usually consists of light boxes, lamps, mirrors, power supplies, controllers, and cooling devices. According to the different materials filled in the lamp, they can be divided into metal halide lamps, high pressure mercury lamps, and ozoneless lamps. Its performance parameters mainly include: arc length, characteristic spectrum, power, working voltage, operating current and average life.
2. Spectral characteristics Although the UV light source emits mainly UV light, it is not a single wavelength light but a light in one wavelength band. For different UV light sources, the wavelength range of the emitted light is different, and the spectral energy distribution in the waveband is also different. Take the example of the M08-L41 metal halide lamp imported from Japan. Its spectral distribution is shown in the figure.
As can be seen from the figure, the UV light source radiates light in one wavelength band, and the energy distribution of the respective wavelength light is not the same. The energy distribution of light with a wavelength of 300-310 nm and 360-390 nm is high. If the photopolymerization initiator in the UV ink used is selected to absorb light of this part of wavelength, its drying effect will be better. This effect is especially noticeable when large ink volumes are printed.
We encountered such a problem when producing printed black marks (black marks require a large amount of ink): the same UV light source, the same amount of ink, the same working conditions, the use of Japanese imports of SPA concentrated UV black ink when the blot is not dry , And to use the domestic Hanghua UV161 black ink, dry well. why? I think this is a question of matching UV inks to UV light sources.
III. Matching of UV ink and UV light source The matching of UV ink and UV light source means that the light quantum selected and absorbed by the photopolymerization initiator used in the UV ink is the part with the highest energy distribution in the UV light source spectrum. For a printing company, it is unrealistic to rely on the analysis of the spectral characteristics of UV light sources and the photosensitivity of UV inks on their own, which deviates from the company's production goals. However, companies should not ignore this problem. Technical departments should obtain technical data on the spectral characteristics of UV light sources from their equipment suppliers, and then select from the ink supplier UV inks whose ink formulation response curve matches the UV light source spectrum. This can better solve the match between the two, but also provides the precondition for considering other factors that affect drying.
Solving the problem of matching the UV ink with the UV light source is beneficial to accelerating the drying speed of the ink, improving the labor productivity, improving the utilization rate of the energy, and reducing the production cost of the enterprise. (Liu Binhui Wuxi Shuanglong Information Paper Co., Ltd.)
First, UV ink 1. Composition UV ink is under the irradiation of UV light, cross-linked polymerization occurs, instantly cured film forming ink. It is mainly composed of a photopolymerizable prepolymer, a photosensitive monomer, a photopolymerization initiator, an organic pigment, and an additive. Among them, the photopolymerization initiator is the most important component of the entire UV ink and is the beginning of photopolymerization reaction. Commonly used photopolymerization initiators include aromatic ketones and esteroin ethers.
2. Features (1) Instant drying at low temperature;
(2) Good gloss and high adhesion;
(3) No solvent, good stability;
(4) strong printability, to meet the needs of a variety of substrates;
(5) Save energy and improve efficiency;
(6) Small environmental pollution.
3. Curing Mechanism Under the irradiation of UV light, the photopolymerization initiator in the UV ink absorbs photons of a certain wavelength, excites excited states, and forms free radicals or ions. Then, a polymer such as a polymerizable prepolymer and a photosensitive monomer is brought into an excited state by energy transfer between molecules, and a charge transfer complex is produced. These complexes continuously crosslink and polymerize to form a film. Its photochemical reaction history can be expressed as:
Among them, D is a photopolymerization initiator, and A is a photopolymerizable prepolymer and a photosensitive monomer. In the course of UV ink curing, the photopolymerization initiator is excited to the excited state, which is a crucial step, and it determines the efficiency of the entire photochemical reaction.
E2-E1=hÏ…...............(1)
In formula (1): E1 is the energy level before the molecule absorbs light energy, E2 is the energy level reached after the molecule absorbs light energy, h is the Plank constant, and Ï… is the frequency of the absorbed light. By formula (1) know:
Ï…=(E2-E1)/h
For A, B two different molecules, there are:
Ï…A=(EA2-EA1)/h
Ï…B=(EB2-EB1)/h
Different molecules: EA2-EA1≠EB2-EB1:
υA≠υB
That is, the two molecules A and B absorb light of two different wavelengths (λ=C/υ, C is the speed of light), that is, the material molecules selectively absorb light. Different UV inks have different photopolymerization initiators. The photons they choose to absorb are also different. Therefore, each UV ink is only sensitive to light of a specific wavelength in the spectrum of the UV light source.
Moreover, the photochemical reaction is related to the number of effective photons. The more effective photons, the greater the chance that the photopolymerization initiator will absorb such photons and the faster the photochemical reaction rate. Assuming that the total energy of a UV light source radiates light is E, and the energy of light with a frequency of Ï… is EÏ…, and the ratio of EÏ… in E is k, then:
EÏ…=kE
In formula E2-E1=hυ, hυ represents the energy of a photon, so the number of photons of frequency 为 is N=Eυ/hυ=kE/hυ
Visible: N is proportional to k, E. That is, the number of photons is determined by the total energy of the radiated light of the UV light source and the distribution of the light energy of each wavelength.
From the above, it can be known that the UV ink selectively absorbs photons of UV light, and its drying is affected by the total energy of the light irradiated by the UV light source and the distribution of light energy of different wavelengths.
Second, UV light source 1. Construction UV light source is a device that emits UV light in a UV curing system. Usually consists of light boxes, lamps, mirrors, power supplies, controllers, and cooling devices. According to the different materials filled in the lamp, they can be divided into metal halide lamps, high pressure mercury lamps, and ozoneless lamps. Its performance parameters mainly include: arc length, characteristic spectrum, power, working voltage, operating current and average life.
2. Spectral characteristics Although the UV light source emits mainly UV light, it is not a single wavelength light but a light in one wavelength band. For different UV light sources, the wavelength range of the emitted light is different, and the spectral energy distribution in the waveband is also different. Take the example of the M08-L41 metal halide lamp imported from Japan. Its spectral distribution is shown in the figure.
As can be seen from the figure, the UV light source radiates light in one wavelength band, and the energy distribution of the respective wavelength light is not the same. The energy distribution of light with a wavelength of 300-310 nm and 360-390 nm is high. If the photopolymerization initiator in the UV ink used is selected to absorb light of this part of wavelength, its drying effect will be better. This effect is especially noticeable when large ink volumes are printed.
We encountered such a problem when producing printed black marks (black marks require a large amount of ink): the same UV light source, the same amount of ink, the same working conditions, the use of Japanese imports of SPA concentrated UV black ink when the blot is not dry , And to use the domestic Hanghua UV161 black ink, dry well. why? I think this is a question of matching UV inks to UV light sources.
III. Matching of UV ink and UV light source The matching of UV ink and UV light source means that the light quantum selected and absorbed by the photopolymerization initiator used in the UV ink is the part with the highest energy distribution in the UV light source spectrum. For a printing company, it is unrealistic to rely on the analysis of the spectral characteristics of UV light sources and the photosensitivity of UV inks on their own, which deviates from the company's production goals. However, companies should not ignore this problem. Technical departments should obtain technical data on the spectral characteristics of UV light sources from their equipment suppliers, and then select from the ink supplier UV inks whose ink formulation response curve matches the UV light source spectrum. This can better solve the match between the two, but also provides the precondition for considering other factors that affect drying.
Solving the problem of matching the UV ink with the UV light source is beneficial to accelerating the drying speed of the ink, improving the labor productivity, improving the utilization rate of the energy, and reducing the production cost of the enterprise. (Liu Binhui Wuxi Shuanglong Information Paper Co., Ltd.)
Catch Balls ,Catch Ball,Catch The Ball,Catching A Ball
Ningbo Sno Stationery & Sports Articles Co., Ltd. , https://www.snotoy.com