What it is?

Why is UV printing so good?

Why pay more?

The principle of UV printing

Ultraviolet printing (UV printing) is a type of printing using UV-curable ink by inkjet printing directly on the material. When exposed to UV radiation of a certain wave, such ink instantly polymerizes and turns into a solid state. Since the ink does not absorb into the material and does not spread over the surface, this allows you to create bright and saturated images.

UV ink has a matte finish after curing, so additional lacquer treatment is required to make it glossy. But if you use printing on glass on the reverse side, the images are juicy and glossy. Thus, the image can be applied to any surface. Glossy surfaces are treated with a special solution before application, which helps the ink to adhere to the surface of the material. Even without varnish, after polymerization, the ink stops evaporating harmful solvents and becomes harmless to humans.

When printing on transparent materials (glass, plexiglass) with white color, we get several layers: base (glass) + primer (for adhesion to the surface) + colored UV inks + white UV ink + white protective security film.

What are the advantages of printing with UV inks?

• Fortitude
  UV ink is very resistant to environmental influences. In addition, they are more durable - they do not fade in the sun and do not dissolve in water and solvents.
• Environmental friendliness
  ​The components that make up UV inks, unlike solvent inks, do not contain resin-based solvents. In the process of working with ink, harmful effects on the atmosphere and humans are practically eliminated. This allows you to use UV printing in places with high sanitary requirements (schools, kindergartens, hospitals) and in the interior.
• Large selection of materials and surfaces
  UV ink is not absorbed into the material, but remains on the surface. That is why you can print on any materials: flexible or hard, with smooth or uneven surfaces.
• Bright and vibrant colors
  Because UV ink is not absorbed and does not spread, the colors do not lose juiciness, and the lack of spreading allows you to print clear images as in the original file. That is why you can print on any surface without loss of juiciness and clarity.
• Durability
  In indoor advertising, the service life of UV printing is 10-15 years, and in outdoor advertising it is limited to 4-5 years. This is due to the fact that outdoor advertising materials are still exposed to ultraviolet radiation and significant temperature fluctuations.
• Printing in white
  ​Currently, very few printers can boast the ability to print in white. At the same time, white color can be a substrate, opaque, and just as a 5th additional color when printing on dark surfaces.

So why pay for UV printing?

The UV printing technology itself is much more expensive than simple interior printing with solvent plotters. But when using printing on a solvent plotter, there are a number of significant drawbacks, including those that are harmful to health, since even after a few days the solvent ink continues to evaporate from the surface of the film. And it is better not to pronounce the list of diseases that it causes in a decent place. For example, let's look at the most common case - the manufacture of skinali (kitchen apron) So, skinali is installed in the kitchen between the lower and upper drawers, in close proximity from cooking. It is natural in this case to use more environmentally friendly products. The tempered glass behind the gas stove is in an area with temperature fluctuations, and the film in such places can "float", with the appearance of bubbles and drying of the film to the center of the glass, which in turn leads to the appearance of transparent stripes along the edges of the skinal. This is especially critical at the junctions of individual glasses. UV printing is deprived of all this, because. it is applied directly to the glass and is not afraid of high temperatures. An additional bonus is the high quality of the picture and printing to the edge of the glass, even bevels are sealed. The difference in the cost of one square meter of photo printing on film and UV printing is 600-800 rubles. With an apron length of 4 p.m. additional costs will amount to 1.5 - 2 thousand rubles. But for this money you will get bright colors, without dust and debris under the film, without transparent edges, with a guarantee for 10-15 years. You deserve a good product for the money spent!

Polymers are active chemicals that have recently gained wide popularity due to the mass consumption of plastic products. Every year, the volume of world production of polymers is growing, and materials made using them are gaining new positions in the household and industrial sectors.

All product tests are carried out in laboratory conditions. Their main task is to identify environmental factors that have a devastating effect on plastic products.

The main group of adverse factors that destroy polymers

The resistance of specific products to negative climatic conditions is determined taking into account two main criteria:

• the chemical composition of the polymer;
• type and strength of external factors.

In this case, the adverse effect on polymer products is determined by the time of their complete destruction and the type of impact: instant complete destruction or subtle cracks and defects.

Factors affecting the degradation of polymers include:

• microorganisms;
• thermal energy of varying degrees of intensity;
• industrial emissions containing harmful substances;
• high humidity;
• UV radiation;
• x-ray radiation;
• an increased percentage of oxygen and ozone compounds in the air.

The process of complete destruction of products is accelerated by the simultaneous action of several unfavorable factors.

One of the peculiarities of conducting climatic tests of polymers is the need for test expertise and study of the influence of each of the listed phenomena separately. However, such evaluation results cannot accurately reflect the picture of the interaction of external factors with polymer products. This is due to the fact that under normal conditions, materials are most often subjected to combined effects. In this case, the destructive effect is markedly enhanced.

Effect of ultraviolet radiation on polymers

There is a misconception that plastic products are particularly damaged by the sun's rays. In fact, only ultraviolet radiation has a destructive effect.

Bonds between atoms in polymers can be destroyed only under the influence of rays of this spectrum. The consequences of such adverse effects can be observed visually. They can be expressed:

• in the deterioration of the mechanical properties and strength of the plastic product;
• increased fragility;
• burnout.

In laboratories, xenon lamps are used for such tests.

Experiments are also carried out to recreate the conditions of exposure to UV radiation, high humidity and temperature.

Such tests are needed in order to draw conclusions about the need to make changes in the chemical composition of substances. So, in order for the polymer material to become resistant to UV radiation, special adsorbers are added to it. Due to the absorbing ability of the substance, the protective layer is activated.

The stability and strength of interatomic bonds can also be increased by introducing stabilizers.

The destructive action of microorganisms

Polymers are substances that are highly resistant to bacteria. However, this property is typical only for products made of high quality plastic.

In low-quality materials, low molecular weight substances are added that tend to accumulate on the surface. A large number of such components contribute to the spread of microorganisms.

The consequences of the destructive impact can be noticed quite quickly, since:

• aseptic qualities are lost;
• the degree of transparency of the product is reduced;
• brittleness appears.

Among the additional factors that can lead to a decrease in the performance of polymers, it should be noted elevated temperature and humidity. They create conditions favorable for the active development of microorganisms.

Ongoing research has made it possible to find the most effective way to prevent the growth of bacteria. This is the addition of special substances - fungicides - to the composition of polymers. The development of bacteria is suspended due to the high toxicity of the component for the simplest microorganisms.

Is it possible to neutralize the impact of negative natural factors?

As a result of the research, it was possible to establish that most of the plastic products on the modern market do not interact with oxygen and its active compounds.

However, the mechanism of polymer destruction can be triggered by the combined action of oxygen and high temperature, humidity, or ultraviolet radiation.

Also, when conducting special studies, it was possible to study the features of the interaction of polymeric materials with water. Liquid affects polymers in three ways:

1. physical;
2. chemical (hydrolysis);
3. photochemical.

Additional simultaneous exposure to elevated temperature can accelerate the process of destruction of polymer products.

Corrosion of plastics

In a broad sense, this concept implies the destruction of the material under the negative influence of external factors. So, the term “polymer corrosion” should be understood as a change in the composition or properties of a substance caused by an adverse effect, which leads to partial or complete destruction of the product.

Processes of targeted transformation of polymers to obtain new material properties do not fall under this definition.

We should talk about corrosion, for example, when polyvinyl chloride comes into contact and interacts with a chemically aggressive environment - chlorine.

Recently, the idea of ​​the universality of plastics and composites, which are expected to solve most of the problems of traditional materials, has become dominant in society (including the scientific community). It is believed that new types of plastics and composites will soon replace not only metals, but also glass, heat-resistant inorganic binders, and building materials. A fairly common view is that by chemical or physico-chemical modification of plastics (for example, their filling), impressive results can be achieved.

To a large extent this is true. However, polymers have several "Achilles' heels" that cannot be corrected by the chemistry and physics of carbon and its compounds. One of these problems is heat resistance and chemical resistance under the influence of the sun and other radiation. UV stabilizers (UFS) solve this problem.

In the presence of ubiquitous oxygen, the rays of the sun have a powerful decomposing effect on polymers. It can be clearly seen from the plastic products lying in the open air under the sun - first fading and whitening, then cracking and crumbling. They behave no better in the sea either: according to environmentalists, sea water and the sun turn plastic products into dust, which the fish then confuse with plankton and eat (and then we eat such fish). In general, without UVC and anti-radiation additives (ARD), the polymer is not suitable for many of our usual applications.

Polymers are sensitive to UV radiation, so the service life of products is reduced under the influence of atmospheric factors due to light degradation of the polymer. The use of a light stabilizer concentrate makes it possible to obtain products with high resistance to UV radiation and significantly increase their service life. In addition, the use of UVC prevents color loss, haze, loss of mechanical properties and cracking in the finished product.

Light stabilizers are especially important in large-area products exposed to solar or other irradiation - films, sheets. The concept of “UV stabilization” means that the film loses no more than half of its initial mechanical strength under the action of sunlight over a certain period of time. UFS, as a rule, contains 20% of “sterically hindered” HALS amines (i.e., amines with a spatial structure that hinders the conformational movements of molecules - this makes it possible to stabilize radicals, etc.) and an antioxidant.

CharacteristicsUV Stabilizers

The mechanism of action of light stabilizers (besides UFS, there are IR stabilizers, etc.) is complex. They can simply take in (absorb) light, releasing the absorbed energy then in the form of heat; can enter into chemical reactions with products of primary decomposition; can slow down (inhibit) unwanted processes. There are two ways to introduce UVC: surface coating and injection into the polymer block. It is believed that it is more expensive to introduce into the block, but the effect of UFS is more durable and reliable. True, the bulk of products (for example, all Chinese) are stabilized by applying a polymer surface layer - as a rule, 40-50 microns. By the way, for a long service life (3–5 years or up to 6–10 seasons), it is not enough to add a lot of UVC, you also need sufficient thickness and a margin of safety. So, for a service life of 3 years, the film should be at least 120 microns thick, for 6–10 seasons, a three-layer material up to 150 microns thick, with a hardened middle layer, is required.

UFS can be subdivided into absorbers and stabilizers. Absorbers absorb radiation and convert it into heat (and their effectiveness depends on the thickness of the polymer layer, they are ineffective in very thin films). Stabilizers stabilize already formed radicals.

In the CIS, both stabilized (more expensive) and non-stabilized (cheaper) forms of polymers are sold. This largely explains the lower quality of cheap analogue products from China or other countries. It is clear that polymers (films) with cheaper stabilization will serve less than the specified period. For example, stability over 10 seasons is often declared, but the degree of stability reduction under increased loads is not indicated. As a result, the service life is often half the declared (ie 1-2 years).

Good examples of the polymer stabilization effect are polycarbonate, polyethylene and films. The validity of polycarbonate in the form of a honeycomb sheet ranges from 2 to 20 years, depending on the degree of stabilization. Due to cost savings on stabilizers, 90% of manufacturers cannot confirm the stated lifetime of PC sheets (usually 10 years). The same with films. For example, instead of 5–10 seasons, agricultural films withstand only 2–3 seasons, which leads to significant losses in the agricultural sector. Polyethylene without UVC does not work for a long time, because it is quickly decomposed by UV radiation (pay attention to the appearance and condition of 10-15-year-old PE products). Because of this, for example, polyethylene gas or water pipes are forbidden to be laid on the surface of the earth and even indoors. It is not recommended to process such large-tonnage polymers as polypropylene, polyformaldehyde, rubbers without UFS and ARD.

High-quality UFS, unfortunately, are expensive (most of them are produced by branded Western firms), and because of this, many local manufacturers save on them (they must be added in an amount of 0.1-2, or even 5%). Instead of new GOSTs, TUs and GOSTs of 20 years ago are used in production. For comparison, in the EU, stabilizer standards are updated every 10 years. Each type of UFS has features that should be considered when using. For example, amine UFS lead to darkening of the material, and it is not recommended to use them for light-colored products. For them, phenolic UVCs are used.

Note that the presence of UVC in polymers, especially films, is not yet taken for granted, which consumers should be aware of. Reputable manufacturers focus on the presence of UVC in any product. Thus, Mitsubishi-Engineering Plastics claims that their NOVAREX polycarbonate pellets contain a UV-stabilizing additive "so that cellular polycarbonate can be used for 10 years under increased exposure to sunlight." A “closer” example is the latest April release of the Belarusian enterprise “Svetlogorsk-Khimvolokno” regarding the introduction of new products - PE films with UVC. In addition to explaining why UFS is needed, the company's press service notes that UFS film "can have a service life of up to three seasons." Information from one of the oldest and most respected enterprises in the industry (founded in 1964, produces chemical fibers, polyester textile yarns, household goods) shows that the consumer must monitor the presence of UVC in the polymer himself.

A few words about the market

The global market for light and heat stabilizers is approaching the $5 billion mark - more precisely, it is expected to reach $4.8 billion by 2018. The largest consumer of stabilizers is the construction industry (in 2010, 85% of stabilizers were used for the production of profiles, pipes and cable insulation). With the growing fashion for siding (whose resistance to light exposure is essential), the share of UVC in construction can only increase. Not surprisingly, the market for light stabilizers is still in high demand - the largest consumer of stabilizers turned out to be the Asia-Pacific region, which accounts for up to half of global demand. This is followed by Western Europe and the USA. Then there are the markets in South America, the CIS and Eastern Europe, in the Middle East, where the growth in demand for UFS is ahead of the average, reaching 3.5-4.7% per year.

Since the 1970s, the world market has been replenished with offers from leading European companies. Thus, for almost half a century, Tinuvin UFS has been successfully used, to expand the production of which, in 2001, Ciba built a new plant (in 2009, Ciba became part of BASF). IPG (International Plastic Guide) has tested and launched LightformPP brand UVC concentrate for films and spunbonds (this is a non-woven polypropylene microporous vapor-permeable insulating material). New UFS, in addition to light protection, protect against the destructive effect of pesticides (including sulfur), which is especially important in the agricultural industry. New UFS have already started to be delivered to the CIS (as a rule, deliveries come from Western Europe, the USA and South Korea). UFS is being developed by Japanese Novarex, Western Clariant, Ampacet, Chemtura, BASF. Recently, Asian producers have become increasingly influential - not only South Korean, but also Chinese.

Dmitry Severin

Nylon cable ties are a versatile fixation tool. They have found application in many areas, including outdoor work. In the open air, cable clamps are exposed to multiple natural influences: precipitation, winds, summer heat, winter cold, and most importantly, sunlight.

The sun's rays are detrimental to screeds, they destroy nylon, make it brittle and reduce elasticity, leading to the loss of the main consumer properties of the product. In the conditions of central Russia, a screed installed on the street can lose 10% of the declared strength in the first 2 weeks. The reason for this is ultraviolet, electromagnetic waves invisible to the eye that are present in daylight. It is the long wavelength UVA and to a lesser extent the medium long UVB (due to the atmosphere only 10% reach the Earth's surface) UV ranges that are responsible for the premature aging of nylon screeds.

The negative impact of UV is everywhere, even in regions where there are very few sunny days, because. 80% of rays penetrate clouds. The situation is exacerbated in the northern regions, with their long winters, as the atmosphere's permeability to sunlight increases and snow reflects the rays, thus doubling UV exposure.

Most suppliers suggest using a black tie as a solution to the aging of the nylon yoke from sunlight. These screeds cost the same as their neutral white counterparts, and the only difference is that in order to obtain a black color in the finished product, a small amount of coal powder or soot is added to the raw material as a coloring pigment. This additive is so insignificant that it is not able to protect the product from UV degradation. Such screeds are commonly referred to as "weather resistant". Hoping that such a screed will work in good faith in the open air is the same as trying to keep warm in the cold by wearing only underwear.

When installed outdoors, only ties made of UV-stabilized polyamide 66 are able to reliably withstand loads for an extended period of time. Their service life, compared to standard ties under UV light, varies significantly. A positive effect is achieved by adding special UV stabilizers to the raw materials. The scenario of action of light stabilizers can be different: they can simply absorb (absorb) light, releasing the absorbed energy then in the form of heat; can enter into chemical reactions with products of primary decomposition; can slow down (inhibit) unwanted processes.

Enamel resistance to fading

Conditional lightfastness was determined on samples of dark gray RAL 7016 enamel on REHAU BLITZ PVC profile.

The conditional light fastness of the paintwork was determined in tests in accordance with the standards:

GOST 30973-2002 "Polyvinyl chloride profiles for window and door blocks. Method for determining resistance to climatic influences and assessing durability". p. 7.2, tab. 1, approx. 3.

Determining the conditional light fastness at a radiation intensity of 80±5 W/m 2 was controlled by changing the gloss of the coatings and color characteristics. The color characteristics of the coatings were determined on a Spectroton device after wiping the samples with a dry cloth to remove the formed plaque.

The change in the color of the samples during the test was judged by the change in color coordinates in the CIE Lab system, calculating ΔE. The results are shown in table 1.

Table 1 - Change in gloss and color characteristics of coatings

Samples 1 to 4 are considered to have passed the test.

The data are given for sample No. 4 - 144 hours of UV irradiation, which corresponds to GOST 30973-2002 (40 conditional years):

L = 4.25 norm 5.5; a = 0.48 norm 0.80; b = 1.54 norm 3.5.

Conclusion:

The power of the light flux up to 80±5 W/m 2 leads to a sharp drop in the gloss of the coatings by 98% after 36 hours of testing as a result of plaque formation. With continued testing, no further loss of gloss occurs. Light fastness can be characterized in accordance with GOST 30973-2002 - 40 conditional years.

The color characteristics of the coating are within acceptable limits and comply with GOST 30973-2002 on samples No. 1, No. 2, No. 3, No. 4.