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Five improve the aesthetic level of uv ink
After corona treatment still cannot meet the requirements of a film should be replaced at this time. Poor printing eligibility film itself. Tag has been attached to the decoration and beautification of goods, due to the improvement of people's living standards and aesthetic level. High quality uv ink label virtually increases the value of the goods, to promote the sale of goods. Compared with paper labels, film label has many advantages, such as the beautiful beautiful, wear resistance, water resistance, corrosion resistance, not easily torn, transparency, good, is now widely used in daily chemical, electronics, alcohol, food, medicine, health products and other industries. Using film class the non-drying label is the label industry development trend in recent years, the quality of the film, processing eligibility and printing eligibility, has a pivotal role on the non-drying label quality. In this paper, the film adhesive labels do a analysis.
The non-drying label commonly used film information and choice
1, the non-drying label commonly used film
Common membrane materials with polyvinyl chloride (PVC, polyethylene (PE polystyrene (PS polyester (PET polypropylene (BOPP acetic acid salts and polyolefin films.
2, film choice principle
Should choose the physical, chemical indicators are qualified film. When selecting film raw materials.
Can enhance the grade of the goods,
1), according to the type of subject matter, the scale, quality, paste appearance characteristics, using the environment and the user's requirements and other comprehensive consideration. Such as made of good transparency polypropylene film can occur without a label on the label transparent bottles of fashionable feeling. Soothe purchase desire of consumers. And polyvinyl chloride (PVC) film flexibility, contractility, opaque, processing property and labeling features are very good, and bright colors, contrast is large, can attract people's attention, have the function of the promotion of goods. To ensure uniform thin film of ink absorption, with small batch print off color.
2), thin film appearance should be smooth and uniform density, density, colour and lustre is consistent, pervious to light. To be qualified strength index. Printing process of printing pressure associated with thin film thickness.
3), the film thickness evenly. If the film thickness, the printing pressure is uneven, can lead to print the handwriting or ink has deep have shallow. If poor strength of thin film, printing film tension, it is difficult to control in the process of the die cutting and waste. Rewinding tension is uniform. Thin film of good flatness.
4), thin film to level off. Uv ink in the printing correct talent when conveying, running, alignment and winding. The rewinding tension of the film is uniform properly, such as tension is too small, thin film base material is flabby, lateral misregister; Tension is too large, such as base material transverse shrinkage, color is not stable, also hard to normal printing. Ageing resistance.
5), the film to have corrosion resistance. Do not fade, the characteristics of small shrinkage, expansion ratio. Such as poor corrosion resistance, easy aging and fading, the label is not made of durable, will also affect the product sales and use. If the contraction and expansion ratio is larger, the not only influence the printing overprint precision, also can make the label deformation in use process, affect product sales and use. Especially high-grade goods, should as far as possible to prevent the goods being expired, and the label has the embarrassing situation of aging (including plastic tag aging aging and ink faded, etc) necessary to carry on the resistance to aging experiment to deal with plastic or label, testing its performance. And cannot be affected with damp be affected with damp.
6), the choose and buy of the film should be in the period of validity. Film appearance beforehand disposal and low surface tension effect detection, because most of the film are polar materials. And glue on the surface adhesion is very poor, so, want to receive attachment for uv ink fastness, requires pretreatment was carried out on the thin film material appearance. At home and abroad application of pretreatment method is the most common appearance of corona discharge. After corona treatment, film appearance in a series of physical and chemical change, surface tension is greatly increased, to improve the printing ink and adhesive on the surface wettability, greatly increased the binding force between the two.
A, the influencing factors of corona treatment effect
1, equipment factors
Applied voltage is 860 kv frequency is 1050 KHZ corona disposal device mainly has three types: solid type, the spark gap type and tube type, corona treatment device of electrode rods, high frequency generator, disposal roller, etc. Among them, the solid type corona treatment equipment quality is stable, low energy consumption, high efficiency, corona treatment device of choice.
2, the electrode gap
Corona glow zone width expansion, increase electrode gap will occur two effects: on one hand. Film glow in the area to stay longer. On the other hand, the energy distribution to the larger volume of air, and ACTS on the membrane surface would reduce the effective energy ratio. Generally, the electrode gap in 1 mm or so to get better effects of corona treatment.
3 ,the output current
Corona treatment effect is poor; Output current increases, the size of the output current has a great influence on the corona treatment effect. Output current is too low. Current disposal effect is enhanced, but when the output current reaches a critical value, the effect of the corona treatment increase is not obvious, so some kind of thin film materials for corona processing, there is a optimal output current.
4, the disposal of temperature
Chemical reaction speed, improve the disposal of the temperature. Reaction levels increase, disposal effect strengthening, but temperature shoulds not be too tall, otherwise it will form new thin layer interface, on the contrary make strength decreased. Different data, disposal of temperature is different.
5, the humidity of the air
Disposition effect will be worse, humidity is big. This is because the water molecules in the air to absorb the local ions produced by the corona. At this point, the workshop should increase exhaust air, moisture near the electrode discharge in a timely manner.
6, the film itself
Different kinds of thin film the disposal effect is not the same,
①The influence of film type. Under the condition of the same treatment. For example, if you want to achieve the same disposal effect, polypropylene film need more energy than polyethylene film.Thicker film need large energy of disposal,
②The effect of thin film thickness. Film thickness affect the disposal of strength. And in the disposal of thin film, due to the drawing speed, friction, film temperature drop less, current can also be relatively small. Corona treatment effect.
③The influence of film density. Density is too high.
7， the disposal of time
The better the results. But the treatment time is too long, thin film appearance of corona disposal the longer. Can make the material aging, produce peculiar smell, a sticky side, gloss issue such as difference of change. In production, the disposal of the length of time associated with the traction speed of film, drawing speed is slow, the treatment time is long, short conversely.
B. corona treatment effect of detection
Thin film coating on 6 cm2 observe changes of the test liquid in the film appearance. If you don't burst 2 seconds after the test fluid, corona treatment effect is through the change of surface tension or bonding strength to embody so by measuring surface tension can detect corona treatment effect. Detection method is as follows: dip in with clean cotton ball stick apply adequate amount to the test liquid. In a high surface tension test fluid test; If less than 2 seconds, test fluid and burst into water droplets shape, need to change a kind of low surface tension test fluid test again. Until a certain test fluid can not burst in film appearance adhere to 2 seconds, at this point, the test liquid surface tension is the surface tension of thin film materials.
Ink layer adhesion rickety fault analyses
Film label printing fault has rare, back glue, etc. This only do a analysis of ink rickety phenomenon.
1. Ink factors
To select the appropriate ink and the correct use of technology. It is best to use each type of film and its match, the corresponding ink, printing ink and the poor adaptability of 1 or a mixture of different types of ink. Before printing ink experiment. At the same time, in order to ensure that the printing effect, when printing, it is best to use the same manufacturer of the same batch of ink, do not mix use different manufacturer production of the same kind of ink. Cause poor drying. Certain drying temperature is highly advantageous to improve the film adhesion force, more than 2 internal residual ink solvents. So general control room temperature in 1823 ℃ advisable, and stick to the air circulation, clean environment.
2. The film factors
Low surface tension value, corona treatment bad 1 film appearance. Or membrane after the disposal of data due to poor storage environment and storage time is too long to causes such as surface tension the attenuation of the failure. Can effectively reduce the surface tension of the ink, different printing ink on the film surface tension have different requirements. Such as solvent ink surface tension of the general requirements for 3.410 2 n/m thin film material of surface tension reaches more than 3.910 2 n/m. Ethanol surface tension is 2.310-2 n/m can be used as water-based ink additives. To improve the ink adhesion fastness. Usually require thin film material surface tension is higher than the ink surface tension 1.010 2 n/m to ensure the ink in film adhesion strong appearance.
Requirement for common label film surface tension is commonly: PE acuity 3.410-2 3.510 2 n/n/mBOPP acuity mPVC acuity 3.510-2 n/mPS acuity 3.910-2 n/mPET acuity 3.810-2 n/m before the use should check whether the film surface tension to achieve the above specification. Adhesion and reduces, 2 thin film absorption of moisture. Film easy absorption of moisture in humid environment. Therefore, the film shall be stored in a dry ventilated environment. These additives will slowly precipitation, 3 additives precipitation. Film will add a certain amount of the machining process in a slip agent, antistatic agent, etc. Such as thin film storage time is too long. Film appearance to form a layer of weak interface layer, thus affect the combination of ink fastness. Therefore, the thin film should be used within the period of validity.