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Sankun UV machine printing is analysed after the concrete implementation plan of the effect of quality control
A, the concept and significance of laminating
Laminating, namely the paster, is to plastic film coated with adhesive, and paper print after heating, pressure sticking together, form a unity of paper-plastic products processing technology. The effect of print, because the surface is much more a thin, transparent layer of plastic film, more smooth shiny surface, thus improve the print gloss and color fastness, picture and text color is more bright-coloured, rich stereo feeling, also have more waterproof, anti-fouling, wear-resisting, folding resistance, resistance to chemical corrosion, etc.
B, the effect of classification is introduced
According to the effect of the process is divided into three types: dry, wet and oily. According to the different raw materials and equipment used, can be divided into the coating and coating film laminating process.
1. The coating of coated
The effect of coating operation on the thin film coating adhesive first, and then hot pressing, but the production process of fire easily.
2. The pre-coated laminating
The process for laminating equipment without glue heating drying system, laminating process is greatly simplified, and the operation is very convenient, and can be used as the boot, production flexibility, at the same time without solvent smell, no environmental pollution, more important is to be able to completely avoid air bubbles, delaminating, such as fault, the product transparency high, has a broad application prospect and popularization value.
Pre-coating film structure consists of base material and rubber, base material is usually for PET and BOPP film, considering from the cost of materials and processing technology, the vast majority of pre-coating film base material with BOPP film, thickness of 12 to 20 microns, the thickness of the rubber for five to 15 microns. According to different processing equipment and process conditions, different thickness of rubber, rubber is divided into hot melt adhesive and organic polymer resin at low temperature. The difference between the two is that the hot melt adhesive glue by the main resin, tackifier and regulator several material blending modification is made, and organic polymer resin as a single polymer copolymer in low temperature.
Because of restricted by technology, production equipment, raw materials, produced by domestic equipment pre-coating film (mostly hot melt adhesive class) are quality defects. Due to the production process is to rely on similar to the coating effect of the process, dissolved colloid with organic solvent, the rubber roller coating with concave anilox roll on the substrate membrane, thus exist insufficient solvent evaporation, operation produce peculiar smell, when using coated after solvent evaporation, the surface is easy bubbles. At the same time, because of the hot melt adhesive by several kinds of polymer blend, in use process, the temperature control is bad will cause in the hot melt adhesive polymer degradation and crosslinking, bad make coated surface. Some pre-coating film adhesive colloid easily with the external surface of the base material, cause bad coiling. Due to the thin rubber, and the surface is not the activation treatment, so easy to generate enough power to print attached defects such as. Because of the hot melt adhesive consists of several kinds of materials, the effect of transparency after significantly worse than pure resin class pre-coating film at low temperature.
3. Water-based laminating
Is carried out on the print surface processing, can improve the print surface gloss and intensity, enhance the aesthetic effect. To measure film coating quality, also need to check the brightness and strength, bond strength, etc. Water-based wet coated with its coated printing high strength, easy recycling, pollution-free characteristics favored by customers.
4. The surface coated
Is a new transfer printing technology, which can cope with exterior complex artifacts, and is suitable for different material, more because of the design, colour and lustre is vivid and significantly improve product added value. This technique is based on special chemical treatment of thin film, after printed on a color pattern, flat on the surface of the water, using water pressure, the uniform design was written in product surface, the only film is automatically dissolved, after cleaning and drying, and then on a layer of transparent protective coating, the product has a different visual effect.
Laminating process according to the cold heat, stress status and material can be divided into cold (cold), laminating, hot (hot) live coated and way of liquid coatings, etc. Thermal laminating technology refers to the precoat binder on heating activation of diaphragm, and through the diaphragm and it will print together; And cold laminating is through pressure, directly by adhesive glue film and print together. Both methods can produce uv protection film, waterproof and friction resistant film and other kinds of special membrane. Recently, also appeared a new technology, called "liquid resin coated" method. Is the transparent liquid with the brush, gun brush, roller or special laminating machine directly on the product surface on a layer of membrane. Technical operations are simple, the price is cheap, but it is not mature.
C, the effect of material selection
The commonly used plastic film are: polyvinyl chloride (PVC), polypropylene (BOPP) and polyester (PET) film and so on. BOPP film (15 to 20 PM) flexibility, non-toxic and high transparency, low price, is the ideal composite laminating process.
According to the performance of the film itself and purpose, film thickness is between 0.01 0.02 mm, subject to corona or other methods, the processing surface tension should reach below 4 pa, in order to have a good wettability and adhesive properties. Corona processing surface is uniform, the higher the transparency is better, to ensure that the print has covered the best resolution. PET transmittance general is 88-90%, several other films transmittance is usually between 92-93%. Thin film with good light resistance, not easy to change color under the light irradiation for a long time, geometry size stability.
Because the film will contact with solvents, adhesives, printing ink, etc, therefore, must have certain chemical stability. Look at the membrane surface should be smooth, no bump and wrinkles, also requires a film no bubbles, shrinkage cavity, pinhole and pitting, etc. For laminating machine adjustment ability is limited, also calls for rewinding, elastic on both sides is consistent, to ensure uniform coating. Of course, the cost is lower.
D, the composite strength
Refers to the resin coated products in plastic film and paper (plate) print the bonding between the fastness, it depends on the size of the plastic film, paper (plate) between print and binder or hot melt adhesive stick force size. Coated, sticky force mainly comes from plastic film, paper (plate) printing off product and adhesive (or hot melt adhesive) between the mechanical bonding force and physical and chemical bonding force.
Is the key to the glue coated fastness and print () ink and substrate affinity. As a film coating industry, printing ink is not selected, namely only adapt to the ink film coating is the only choice of the market, look for pre-coating film only adapt to all the performance of the ink is high quality. The strength of the composite resin coated products are affected by the effect of the process parameters in the process of production, such as laminating process of temperature, pressure, speed, adhesive coating, film tension and environmental factors. At the same time, the printing process, such as surface after printing the form printing quality status, such as ink layer thickness, the graphic size and distribution, printing ink features, thinner, the use of powder, ink layer drying condition, etc.
E, the influencing factors on the quality of the coated
1. The printing ink layer status
Refers to the nature of the paper, ink, ink layer thickness, the density of the graphic area and printing graphic, etc. When printing ink layer thick, graphic area is large, will be closed many paper fibre wool stoma, obstruct the adhesive penetration and diffusion, print and the plastic film is hard to bonding, prone to take off a layer, such as blister failure.
2. The environment humidity
Adhesive with plastic film and print, along with the changes of air relative humidity change water content. Sensitive to humidity will print due to changes in the internal stress. Such as: print longitudinal extension rate was 0.5%, the longitudinal heat-shrinkable BOPP film is 4%, if print water quantity is too large and elongation, and thin film between heat shrinkage internal stress, can lead to a curly coated products, wrinkle, sticking not firm. In addition, in humidity high environment, balance moisture value of the printed matter will also change, absorption of moisture from the air medium, in the heart of the extrusion compound process was released from the surface, stagnation in the bonding interface, local forming non sticking phenomenon. Moreover, printed matter balance moisture values change (moisture from the air medium or medium into the air into the wet) tend to occur on the edge of the printed matter, make its forming falbala or tight edges, not easily in hot pressing composite film formation good bonding with and produce wrinkles, make production can't run smoothly.
3. The temperature control
Heat can soften the film, adhesive paper and plastic film. But the temperature is high, film easy to fracture, the serious influence product quality, therefore should adopt fan cooled, close the heating wire and other measures.
F, plastic coated greening development trend
After coated paper could not be recycled and become a kind of white pollution, and in the process of the coated with toxic substances such as toluene, day take water volatilization, impair the health of people. In advocating "protect the environment, protect resources" today, plastic coated process in Europe and the United States and other countries have been eliminated, the European and American countries refused to even have a import of plastic coated all kinds of packing materials. Although there are water-based plastic laminating process and hot melt pre-coating film in dry plastic composite technology, but the former have failed to solve the problem of laminator can't print waste degradation can't recycle, which need a large amount of heat in the process of production, and waste should be carried out in 60 ℃ water to paper, plastic, the cost is higher. With the improvement of environmental awareness, the new scientific and technological achievements will out old technology products, qualitative change in the laminating process, "non-toxic and harmless, green environmental protection" naturally become inevitable trend of the development of coated process. In addition, the polishing process is favored. Just use way of printing, coating, spray, or add a layer of colorless transparent coating in the surface of printed matter, namely the glazing oil, after calender, dry treatment, increase the gloss on the surface of the printing quality, also improve its stiffness, at the same time polishing after printing quality waste can be recycled or decomposition, polluting the environment, and so on the processing technology of the light is a kind of very has the development potential, is likely to gradually occupied plastic laminating technology market. Although oily gloss and alcohol on the market at present glazing dilution machine were adopted by the toluene and alcohol, but is also harmful to the human body and adverse to the environmental protection, waterborne glazing has gradually become the mainstream of polishing process. Has now developed a water-based UV glazing process is an ideal environmental protection polishing process, is also the development direction of polishing process.