Analysis of the method of producing refraction eff

2022-08-08
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Analysis of the method of producing refraction effect on the surface of metal substrate

refraction effect is the surface finishing process effect of processing on some substrate surfaces with metal texture, so that they have both changeable metal luster and clear and discernible three-dimensional images in all perspectives. It is widely used in book covers, tobacco and alcohol packaging, wall calendars, desk calendars and greeting cards, showing a magical effect of infinite change and glittering, which can greatly improve the product grade and enhance the anti-counterfeiting effect of products

to produce refractive effect, the first condition is that the surface of the substrate has metallic luster, and it is best that the luster reaches a certain specular reflection effect. The second condition is that the surface of the substrate is printed with refractive texture. Refractive texture is a texture pattern composed of a series of regularly parallel, equidistant, and very thin solid lines with several different angles. The formation of refraction effect is the result of the interaction between light and refraction texture. After the light enters the printing surface with refractive texture from all directions, due to the influence of refractive texture, the reflected light produces more directional reflection, and some light even produces interference phenomenon to strengthen the reflection effect, and finally forms a sparkling refractive effect

according to the common types, the refraction process can be divided into three types: traditional mechanical refraction, laser refraction and currently more popular printing refraction. In fact, the essence of these three methods is the same, all of which copy the refraction texture pattern to the substrate surface through imprinting. Mechanical refraction is to engrave the refractive texture pattern on the metal plate by means of laser electronic engraving or corrosion, and then use a lot of pressure to transfer the refractive texture pattern to the surface of the substrate. Mechanical refraction can be achieved by round flattening or flat flattening. The round flattening method is suitable for large-scale and mass operations; The flat pressing square type is suitable for local small area and small batch operations

the imprinting method of laser refraction is somewhat similar to mechanical refraction, but the formation of its refraction plate texture is much more complex: first, the laser records the image information on the holographic recording material, and then uses the method of electroforming to copy the refraction texture onto the rigid metal template to form a very dense grating that cannot be recognized by the human eye. Mechanical refraction and laser refraction do not need ink, just through a rigid template, use pressure to imprint the refraction texture on the surface of the substrate, and printing refraction requires ink, namely UV refraction ink. Printing refraction is to copy the refraction texture printing test sensitively to the substrate surface by means of silk printing. The printing refraction method is simple, and the technical requirements are not high. Although the production efficiency is relatively low, and the anti-counterfeiting effect is slightly inferior to mechanical refraction and laser refraction, the refraction effect is also very strong, and the average cost is low for small batch products. Therefore, Indo refraction has developed rapidly in recent years and is highly respected by many small and medium-sized enterprises

process flow of refractive printing: original design → production of electronic refractive texture → output of refractive texture film → stretching and coating photosensitive adhesive → close contact exposure of film and silk → development → revision → silk printing → UV curing

design and production of refractive texture

when making refractive texture, some pictures are generally used as the base map to be simulated by the refractive texture lines, such as company logo or Chinese and English names. The refraction texture lines of these signs and names can be represented by parallel lines. It is best to arrange the line angle at 45 ~ 60 degrees or 120 ~ 135 degrees. In this way, when the work is placed horizontally, the refraction effect of the logo or name will be very prominent. Around the refraction texture of signs and names, some central radial lines can be designed, or monotonically repeated geometric figures with regular distribution and arrangement. The angle of refraction texture lines of these geometric figures should not be too much, generally 4 ~ 7. If the angle is too large, the reflection of light will be scattered, and the refraction effect will naturally not be very strong. There is also a strict requirement for the thickness of texture lines and the design of line spacing. Generally, the thickness is required to be between 0.10 ~ 0.15mm, and the line spacing is generally equivalent to the size of line thickness. Too thin lines, such as 0.08mm, not only have high requirements for printing silk plate and ink, but also printing is difficult to restore; Although the thick lines have low technical requirements and are easy to print, the refraction effect is poor. For products that need close observation and appreciation, such as book covers, greeting cards, cigarette and alcohol packaging, thinner lines can be designed, while for works viewed from a distance, such as wall calendars, thicker lines can be designed

there are special software for the design and production of refractive texture patterns, and the domestic well-known ones include founder hyperline 3.0 anti-counterfeiting design system and Montaigne 5.0. Through them, as long as you have some art skills and master certain operating skills, you can easily design some refractive texture patterns. After designing the electronic texture pattern, you can output PDF documents, or directly output the film through the laser Imagesetter for plate making

production of refractive plate and related requirements

1. selection and tension of silk

first of all, appropriate silk should be selected, which requires good elasticity, friction resistance, very small expansion rate, large holes, and thick photosensitive material layer. In practice, we choose nylon yarn with good ink passing performance and stretched, and the mesh number is 450 mesh/inch

2. Apply photosensitive glue

the photosensitive glue solution should be slightly thicker. The coating of photosensitive adhesive should be uniform and flat, and have a considerable thickness. Generally, it needs to be coated many times to ensure that the printing ink layer has sufficient thickness

3. exposure

in order to ensure that the fine and dense refraction lines can be completely exposed, you must use a plate printer with a vacuum adsorption device to print. When printing, the film should closely fit with the photosensitive film surface of the plate, and the exposure time should be accurately controlled when printing

4. Development

put the dried silk plate into the pool in the darkroom and soak it for 1 minute. Then use a high-pressure water gun to flush water to the plate, and use water pressure to wash away the photosensitive glue in the line part of the refractive texture image. Of course, pay attention to adjust the water pressure and the uniformity of water mist during flushing. Dry the plate after full development

5. Revision inspection

check the layout for pinholes, bubbles and other defects, and repair them

6. Secondary exposure

after drying the plate, it is necessary to conduct secondary exposure to completely solidify the photosensitive film of the plate and improve the printing resistance of the plate

choice of ink

because the surface tension of mirror printing materials (such as gold, which makes fruits and vegetables durable for silver cardboard) is smaller than that of ordinary paper, the printing ink must choose the UV refractive ink dedicated to gold and silver cardboard, otherwise it is difficult to smoothly transfer the ink to the surface of the substrate with other ordinary UV inks. When printing, a certain proportion of diluent specified by the UV refractive ink manufacturer can be added appropriately according to the viscosity and transfer of the ink

silk printing

taking the use of semi-automatic silk printing machine as an example, this paper introduces some points that need to be paid attention to in the printing process

(1) the same type of UV refractive ink produced by different manufacturers. 4. Regularly check whether there is overheating and abnormal noise in each click, circuit board and electrical appliances. There are certain differences in quality and performance. Generally, it is necessary to pass the printing test first to confirm that the quality is stable and reliable before mass production

after printing, it is cured by UV device under standard conditions. Then the refractive ink, adhesion, scratch resistance and folding resistance of the printing surface are tested. If the test results do not meet the requirements, it is necessary to adjust various conditions, including ink, light intensity, temperature and humidity, until satisfactory results can be obtained. During the test, it is recommended to use UV light quantity measuring instrument

(2) the ink must be fully stirred before use

(3) pay attention to spot check the curing condition of UV refractive ink during printing, so as not to affect the hardness and adhesion fastness of the ink layer due to incomplete curing

(4) during production, pay attention to keeping the temperature of the darkroom at about 23 ℃ and the air humidity at about 60%, so as to prevent the fluidity and transfer performance of the ink from being affected by the fluctuation of environmental conditions. At the same time, pay attention to maintaining the ventilation of the darkroom to disperse the gases harmful to human health

(5) UV ink is irritating to the skin. Be careful when taking it and avoid contact with the skin. If the skin is stuck with ink, wash it immediately with soapy water

(6) the storage period of ink is generally 6 months. It should be sealed and stored at a low temperature (2 ~ 18 ℃), away from light and heat, so as to avoid the change of ink performance

the anti-counterfeiting effect of printing refraction is slightly less than that of mechanical refraction or laser refraction. It is relatively easy to imitate and make, but its appearance effect is not inferior to the latter two, and it is easy to design and make, and the cost is low. It is expected that this method will be more and more widely used. (end)

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