Basics pad printing

 

Basics pad printing.

 

Areas of application pad printing.

 

The application range of pad printing is almost unlimited.

Pad printing is used:

in the production of souvenirs;

in the automotive industry (levers, buttons, instrument panel, etc.);

in the manufacture of electronic products (switches, buttons, tapes, CDs);

in the manufacture of toys (printing on constructors, cars, trains, etc.);

medicine (syringes, tablets, capsules);

food industry (chocolate bars and candy);

the production of goods for sport and recreation: balls, balls, etc.).

 

Benefits pad printing.

 

The ability to print on curved surfaces;

high speed printing;

a small amount of paint.

 

Disadvantages pad printing.

 

Limited field of printing. (Depending on the format of a cliche form of printed products and tampon format);

a thin layer of paint (regardless of the depth of cliche tampon can not "take" of the printed form the paint);

high cost of cliches and tampons;

necessary components plot tampon.

 

Technological stages.

 

Film output for each color and size;

manufacturing of a cliche for each color and size;

manufacturing of equipment under the form of printed products;

mixing paints to Pantone;

commissioning;

print edition.

 

Required elements for tampon.

 

1. Key ingredients for pad printing.

Cliche - this plate with a recess which forms the shape of the printed image. Cliches are steel and polymer. Polymer cliches used in small print runs (5000-10000 products). Steel can withstand millions of readers.

Tampon - is resiliently elastic element made ??of silicone rubber. Dimensions, stiffness and geometry of the tampon selected on the basis of the printed image and the shape of the product.

Colorful bath with form roller (forrakel) and a cleaning device (doctor blade) or closed ink system (the role of the doctor blade and the form roller perform colorful "glass").

The blade - is a device that consists of a metal spatula (for open systems) or ceramic disk (for closed systems), its task to fill the printed image and scrape the excess paint with a cliche.

Forrakel - is a device that is a plate with a groove (sometimes roll), his task is to return the paint on the cliche, thereby filling its printed image.

Bath cliche - a device that is installed in cliches and filled with ink.

Accessories for the printing products.

2. The exposure apparatus for pad printing.

The most important equipment for platemaking are exposure apparatus. These units come from mechanical or vacuum principle. Vacuum principle preferable because it provides a more detailed slide contact with the photopolymer plate, especially when playing back images with small elements (silhouettes), including raster. Loose connections will cause a copy effect. As the light source of the exposure apparatus (ET) tube fitted more UV lamps. EI vary in format, the number and wattage.

3. Developer kit.

You can show photopolymer printing plates, using a set of manual developer:

trays for developing,

brushes for washing,

alcoholmeters,

thermometer.

4. Consumables.

set photopolymer plates,

set of necessary tampons,

set of paints, solvents, and hardeners.

 

Printed stages.

 

1. The initial state of the printing machine.

a. Tampon is above product.

b. Paint thrown over cliches (the image is a cliche paint).

c. Product is installed for printing.

2. Lowering of the blade.

a. Tampon is above product.

b. Paint thrown over cliches (the image is a cliche paint).

c. Product is installed for printing.

d. Raquel goes on cliches.

3. Moving swab and cleaning paint from cliches.

a. Swab moves toward cliche.

b. Paint peeled off with a squeegee cliche (in recesses images paint remains.)

c. Forrakel immersed in a colorful bath.

4. Lowering the swab onto the cliche.

a. Tampon falls on cliche when contacting the cliche is its deformation.

b. The paint comes into contact with the surface of the tampon.

5. Tampon fence paint from cliches.

a. Tampon rises from cliches away with their paint.

b. Paint goes on a tampon with cliches.

6. Move the swab to the product.

a. Swab moves to the product, bringing with them paint.

b. Paint is on the swab.

c. Forrakel painted on cliches, filling the printed image.

7. Lowering the swab onto the product.

a. Tampon falls on the product and deformed, repeating its shape.

b. The paint comes into contact with the workpiece.

8. Closing printing.

a. Tampon rises from an article giving him paint.

b. Ink is transferred from the swab on the product.

c. The machine returns to its original position, the print cycle is complete.

As a result, we see how to use a tampon elastic flat image is transferred to the pad on the cylindrical handle the product. Similarly it is possible to print an image on a complex surface, for example even walnut shells.

 

Printing problems and how to resolve them.

 

Problem

Reason

Elimination

"Torn" edge logo (fuzzy outline)

Too thick paint dries on clichés

  • add solvent
  • wipe pad solvent
  • increase the speed of printing
  • add retarder

Paint dries on the swab

  • increase the speed of printing
  • add retarder

Too deep cliches

Wash finer cliche

Tampon too flat

Replace swab more pointed shape

Rough surface of the tampon

Replaced by another, without damaging the surface

Oily or contaminated substrate surface products

Degrease the surface of the printing material alcohol

Tampon bad takes paint with clichés

Too thick paint dries on clichés

  • add solvent

Paint dries in clichés

  • increase the speed of printing
  • add retarder

Too shallow clichés

Wash deeper cliche

Too deep cliches

Wash finer cliche

Tampon too flat

Replace swab more pointed shape

Worn working surface of the tampon

Change to a higher quality

Oily or contaminated surface of the tampon

Clear tape

Insufficient pressure on the swab pad

Increase the pressure on the pad tampon

Tampon gives bad paint on the product

Paint dries on the swab

  • remove blowout
  • increase the speed of printing
  • add retarder

The paint is not "dosyhaet" on the swab

  • include blowout
  • add fast solvent
  • reduce printing speed

Correctly matched paint series

You must pick a series of paint that is suitable for the printing material

The irregular shape of the tampon

Swab pick the correct form

Worn working surface of the tampon

  • oil lubricated tampon
  • changed by a new

Insufficient pressure on the tampon product

Put pressure on the optimal product (tampon logo gives +15%)

Oily or contaminated substrate surface products

Degrease the surface of the printing material alcohol

Low ambient temperature

Enable heaters

Voids fine lines

Paint dries in clichés

  • increase the speed of printing
  • add retarder

Paint dries on the swab

  • remove blowout
  • increase the speed of printing
  • add retarder

Too deep cliches

Wash plate with optimum depth (smaller than the rams and thick lines)

The irregular shape of the tampon

Swab pick the correct form

Worn working surface of the tampon

  • oil lubricated tampon
  • changed by a new

Excessive pressure on the swab cliche

Reduce the pressure on the pad tampon

Heat on a tampon site

Lower the temperature by using air

Low humidity in the room

Include humidifierа

"Spraying" paint

Tampon gives bad paint

see the problem of "bad tampon gives paint"

Paint is too thick

Add solvent

Too deep cliches

Wash finer cliche

Low humidity in the room

Include humidifier

Low ambient temperature

Enable heaters

"Dot gain" logo

Too deep cliches

Wash finer cliche

Paint is too thick

Add solvent

Excessive pressure on the swab pad

Reduce the pressure on the pad tampon

The irregular shape of the tampon

Swab pick the correct form

Worn working surface of the tampon

  • oil lubricated tampon
  • changed by a new

Uneven shading

Tampon gives bad paint

see the problem of "bad tampon gives paint"

Tampon bad takes a paint

see the problem of "bad tampon takes paint"

 

Cliche for pad printing.

 

To choose the right cliche, you need to consider several important factors:

The number of copies that you want to print,

print type: multicolored, thin characters, halftone, four-color, etc.,

print quality,

type your pad printing ink system equipment (open or closed system),

whether there is an opportunity to make a printed form on this cliche.

 

Photosensitive metal plates for pad printing.

 

Thin steel plate have a thickness of 0.3 or 0.5 mm. These cliches are made of special stainless steel with superb resistance to mechanical stress and have a hardness of 53-55 Hcr.

The process of preparing printing plates includes chemical degreasing plate surface, applying and drying the copy layer exhibiting photoforms manifestation and treatment of copies, etching.

Cliches of this material more durable than photopolymer, and have a fixed etching depth. Due to its hardness such cliches do not require a raster display and intended only for the bar (bezrastrovyh) works. They also have a significantly higher run length (from 100 000 to 250 000 prints).

 

Steel plates for pad printing.

 

Cliches are made of special stainless steel, resistant to oxidation, 10 mm thick.

This cliche is adapted to be etched on both sides. Level the surface roughness corresponds to a high print quality. Hardness of steel: 61-63 Hrc.

Have a more serious run length (up to one million impressions), which is a major advantage of steel cliches. Such cliches are made on the complex, multi-technology and, as a rule, made ??to order for very long runs. Because of the extremely high cost and long manufacturing process in advertising pad printing steel cliches do not apply.

 

Photopolymer printing plates for pad printing.

 

Differ in the number of layers of the photosensitive material (single and double layer) and vymyvnym solution (spirtovymyvnye and water wash). They consist of the photosensitive coating with a thickness of about 0.2 mm, the metal substrate 0.3 mm thick and the adhesive layer providing the bond of the two layers. The photosensitive layer protects the special film. The most common use of two-layer plate.

Single-layer photopolymer printing plates are used only in cases of very clear images of small size, without any significant dice. Furthermore, they are significantly more expensive than bilayer.

When manufacturing spirtovymyvnyh cliche as a developing solution (removing portions of the photosensitive layer, corresponding to the picture elements) used alcohol. This water wash, respectively, water. Spirtovymyvnye provide better print quality and stability than water wash.

 

Process.

 

In polymer cliches rather soft surface. The blade moves along the pad at a predetermined pressure, and therefore sinks more deeply into the areas of the image (die) that are parallel to the blade edge because of what appears on the seal area with varying ink densities. This effect is called "scooping". To eliminate this effect re-used cliche exposure through raster grid (so-called "reference raster").

The "die" cease to be open recessed area on the pad, and it becomes a collection of small projections ("peaks" or "pillars"). These "pillars" support the doctor blade and eliminate "scooping", the paint layer becomes smoother. Repeated exposure is only possible when using two-layer plate.

 

Tampons for pad printing.

 

An important element in the process of obtaining a print tampon - elastic- elastic link that renders an image from the printing plate to the printing surface. Process capability and quality of the print is largely dependent on the properties of tampons - hardness and elasticity, the ability to perceive and to give the paint, abrasion resistance to the action of the components of the ink and solvents. Tampons are made of elastic- elastic materials capable of reducing compression to its original shape without significant residual deformations.

Properties tampon play an important role in the proper transmission of images. The tampon should have a smooth surface and a predetermined geometrical shape that provides contact with a printing plate and the printing surface without slippage.

Swabs used today are made of silicone rubber. They may have very different configuration, which is determined by the shape and dimensions of the flap surface.

 

The shape of the tampone.

 

Tampons have different geometric shapes, which mainly depends on the nature of the image and forms a sealed product. The shape of the tampon is selected so as to provide a "ro-ro" movement of the material of the tampon at its lowering both intake ink pad, and on the object - for printing. Without this "rolling" under the swab remains air, causing image distortion and uneven printing. All forms of tampons can be divided into three groups:

circular

rectangular

cylindrical

 

The size of the tampone.

 

A prerequisite for the achievement of high-quality print is in contact with the tampon printing plate sealing surface and the desired value of the contact zone. The width and length of the tampon is determined primarily transferred articles size.

 

The rigidity of the tampone.

 

One of the most important characteristics of tampons, affecting their performance indicators is stiffness. Stiffness is the body's ability to resist the formation of deformation. The rigidity of the tampon and the pressure created by it in the contact zone of the printed affect the completeness ink transfer from the printing form to the surface of the tampon.

The rigidity of the tampon is typically determined by the amount of silicone oil used in the molded tampon - the oil is, the less rigidity. Hard tampon printing less deformed and therefore transfers the image better. In addition, it is more durable. But there are times when the use of hard tampon is not possible. These cases include the following situations:

printing on a fragile, glass product (ORNAMENT),

print on a soft surface (rubber),

since the hard tampon can deform product,

resealable product has a large curvature (mug, glass).

In this case, soft tampon provide better ink transfer.

Swab must satisfy a number of requirements. The material of the tampon must be uniform, without any extraneous inclusions having different hardness or elasticity. The presence of this deficiency may lead to marriage, especially when printing fine details. Swab should have a smooth work surface and well-defined shape. Its hardness must be between 2-30 units. Shore A (Shore).

Shore Hardness (Shore) - method of determining hardness of very hard materials, primarily metals, the height to which bounces after hitting a special pin (Regular part Scleroscope Shore), freely and vertically falling from a certain height. Hardness Shore this method is evaluated in arbitrary units proportional to the height of the rebound of the striker. Method and scale proposed American industrialist Albert F. Shore in 1906. Denoted HS, where H - Hardness, S - Shore.

Particular attention should be paid to the tip of the swab. This is the most difficult area, especially when printing dies. If the tip of the tampon may not touch the gaps, you should use the tampon with an average angle of rolling and a more acute angle. At a corner of the flat tampon rolling would be too small and this would lead to the formation of gaps in the image. If you use too acute tampon contact areas and there would be too much pressure, which dies when printing to paint squeezed.

In some cases, the new tampon without surface pretreatment does not accept ink. Initially, the surface should be wiped with a tampon paint thinner with a soft cloth. During breaks and after work swab should be cleaned inactive solvent (eg, ethanol).

Tampon run length can vary from a few hundred to hundreds of thousands. It depends primarily on the state of the object and print circulation with a tampon. Sharp edges of printed products or dirt particles in poor cleaning and storage can greatly reduce the life of the tampon. The tampon fails primarily because of swelling in aggressive solvents. The lower hardness of the tampon, so it contains more plastfikatora which leaches and tampon swells.

 

Principles of pad printing.

 

In order to understand why the temperature fluctuations and other changes in the environment can have a profound effect on the quality of pad printing is necessary to recall the basic principles of pad printing. In order to paint silicone tampon took with cliches and moved it to the printed material, with a surface tension of paint should happen very fast changes caused by the evaporation of solvents. Moreover, pad printing - is a thin-film process. It begins with etching depth cliche - only 25 microns... and only about half of the paint takes a tampon. While 60 % of the paint falls on the solvent evaporating during the movement of the tampon, leaving only 5 - micron layer of dry paint on a portable thing.

And now it must be clear why this thin layer of paint is so sensitive to changes in temperature, humidity, static and even to change air flow caused by an open window or door to the shop. Controlling percent solvent evaporated from the paint - this is the key to overcoming the effects of the changes occurring in the environment. When the solvent evaporates too quickly, the paint did not even manage to take a cliche - it just dries to form cavities! If the solvent evaporates too slowly from the surface of the tampon may not be sufficient for the adhesive to lift ink from the depressions form. Under these extreme values ??both of which result in the same result - an insufficient amount of paint or to its absence on the swab. Furthermore, if the paint is on the tampon, the effect is similar. When the solvent evaporates too quickly, the paint dries and remains on the swab. If the solvent evaporates too slowly to pass the tampon onto the surface of only a small amount of paint.

 

Adding solvents.

 

In most cases, you will need a pad printing process to regularly add the solvent in the paint. How long will it add and how often will depend on the environmental conditions and the type of equipment you are using. Machine with closed ink system, for example, do not allow the evaporation of solvents from the colorful bath (cup), therefore, tend to enhance the solvent during operation is not required. In a warm room , with open squeegee system, pad printing process you 'll need to add solvents every 20-30 minutes. But remember, always add a fixed number - do not do it at random!

The use of certain solvents for pad printing provides full control over the process of pad printing. Various solvents for pad colors have different boiling points. Those who have low boiling point, known as rapid and volatile, the boiling point above, known as slow and evaporate slowly. Usually when selling ink for pad printing features a standard set of solvents, suitable for a standard climate. But no worries - you can always mix your own composition. Do not mix solvents from different manufacturers.

 

Control of temperature and air flow.

 

The more stable the environment, the more effectively you can control this process. It would seem, install air conditioning - and no problems! But the room temperature is not all! There are several other settings that you want to control, but which are not so obvious. For example, install the pad machine away from direct sunlight. You should not put pad printing machines close conveyor dryers. Do not place the pad machine in those areas of production facilities, which are subject to significant temperature fluctuations, even if they are air-conditioned, for example, at the entrance/exit from the premises.

If the room where you work, the air conditioning is missing, you can get away from using construction dryers or heaters. When the temperature is low, and the solvent in the paint, evaporates quickly enough, hot or even cold air flow generated by the fan or fan on a swab or on the printed surface, much will improve the result of the tampon. And then, through trial and through experimentation, you can determine the desired speed, temperature and air flow direction in the process of printing.

Do not forget about the role of temperature, regardless of the process pad printing. It is about the storage of printed materials up to, and in some cases and after the tampon. Often printed materials are kept at the warehouses, which are not heated. And when you bring these materials to a warm place, especially in the winter period, the difference in surface temperatures will lead to uruchomiono result. On the printed surface can produce a very thin layer of condensate, which is generally not visible to the naked eye. In such conditions it will be difficult to make a good impression or acceptable adhesion of paint. To prevent this, bring the materials to the shop for a few hours before printing, to give them time to Mature to a stable temperature. Products, which must be stored after printing, also may be exposed to low temperatures. If you use two-component pad paint, let's not sealed products to get to the temperature below 15 C until then, until they are fully dry (hardened). Remember that the process of hardening pad paint can last up to four days and even longer. If the temperature of the products will fall below 15 degrees Celsius, the pad paint will cease to harden and in the future may crumble with the printed product.

 

Dust control on site.

 

Keep the tampon machine away from windows and ventilation systems. For example, do not place it in a duct or vents. The circulating air is not only provides a rapid evaporation of the solvent, but also can cause contamination especially when printing images or large enough for the image printing a few times to increase the opacity of the print. Many products they work with printers pad printing , packed in cardboard boxes , which, of course, causes the formation of dust. Hence the rule: unpack the product away from the tampon machine. Dust in your workplace will fall on the sticky parts of printed materials, printed contaminate the swab. In addition, dirt will shorten the life of the tampon. The only way to overcome this problem - always maintain the cleanliness of the room where the equipment is installed tampons. Need to vacuum the floors, rather than sweep them as a broom (broom) only moves the dust and that inevitably settles on cliches colorful bath and other items tampon machine. Cleaning should be done at night, after production has stopped. Wipe all surfaces, not just the floor cloth. Use during off hours chandelier Chizhevskogo to reduce dust levels in areas where there are Tampon machines.

 

Control of humidity and static.

 

Often experienced printers pad printing boil kettle next to the tampon machine - not to make coffee and to get the water vapor in the dry cold days when the actual problem with static. Low humidity often causes problems with most types of printing processes in the same machine when using the tampon static electricity generated as tampons silicon is a dielectric, which is deformed during printing. In addition, we often print on plastic surfaces, which creates an additional source of static electricity. A typical result of static electricity on the pad printing process is the formation of non-printing elements (baldness) on the printed surface. And the reason is not lack of depth in the form (cliche) you persecuted. Unfortunately, this problem harder to solve than the notice. The simplest solution - Reduce the amount of static electricity by reducing the speed of the tampon machine in the first place on the stage of the fence paint and its impact. Tried grounded swabs and cliche, but it helps to solve this little problem. Brings more benefits to find a boiling kettle or autonomous humidifier next to the machine. If you use a humidifier, make sure it is self-regulating and can maintain the desired humidity level.

Other features that reduce static in the pad printing process is the use of antistatic agents and coronary dischargers. Antistatic devices reduce defects classic "needle-like spray" paint with tampon, but you should be careful using them, because sometimes they can destroy the chemical composition of the paint. A coronary discharger can use only when pad printing on films or other flat surfaces.

 

Control over the speed of the machine.

 

Another problem, which overlooked some printers, is how fast the tampon machine. By adjusting the speed of the tampon machine, you give more or less solvent evaporation time, allowing you to some extent to respond to changes in humidity in the premises in the workplace. By lowering the speed pad printing and also reduced the amount of static generated during tampon tampon.

The most common mistake made in this case is that the tampon are too high speeds. Speed ??reduction can often improve the quality of pad printing and reduce the number of marriage. Besides pad printing at low speeds fence provides more ink from the cliche and transfer it to the printing surface, which increases coverage. Besides decreasing the vibration machine, and in this case the operator can monitor the quality much more closely. Remember that you are critical of the number of prints of good quality, not the number of cycles performed tampon machine. Main components of the printing cycle tampon machine - it's control over the fence paint and its impact . I would not discuss the purchase of an automatic machine that does not allow to adjust the speed of the two phases (known as "dwell time"). This function allows you to fine-tune the printing process, because how tampon rose or fell on cliches and the surface determines the specific framework and tolerable amount of paint. You are trying to achieve a soft, laminating motion tampon and "soft" often means " slow". Machine without time adjustment function "dwell" is also able to work adequately, but this feature is truly irreplaceable when you encounter print quality problem and you need to maintain the speed of the machine.

 

Control of variable parameters.

 

We examined how environmental conditions may affect the print quality, but this does not exhaust the important parameters of the printing process pad printing. The key to successful tampon - in control over all parameters. But remember, whenever you are faced with the problem of quality, never change more than one parameter at a time and always write down what settings you have accomplished. Store samples and assign them numbers according to their records, so you can always see what changes have improved and which affect print quality.

 

Steps for setting up the tampon machine.

 

1. To pick up a tampon in shape and size depending on the size and shape of the logo printed surface.

2. Snap to prepare for the product. The main requirement for snap - product must be installed in a snap without play (for non-standard products using plaster molds).

3. Positioning of the printing plate relative to the tampon.

4. Position the product relative to the image, which is located on the swab.

5. Print test page.

 

Pad printing inks.

 

Pad printing uses special inks that unlike stencil should be smaller and pigments to be more intense, have a high intensity to provide sufficient opacity, moreover, the paint must be tacky, flowing and possess special print - mechanical properties.

 

The ink composition.

 

Pad printing inks include the following components:

Coloring agents (pigments or dyes).

Binder (resin).

Solvents.

Additional additives.

Colorants. Colorants are pigments or dyes. Dyes soluble dye in a medium (solvent). In the dyeing process, they penetrate into the material and form a more or less strong bond with the fibers. Pingmenty insoluble. In the ink, they are in a binder (varnish, nitrocellulose, etc.) and the properties of the paint binder is more dependent than that of the pigment. Communication with coloring materials provides a binder. Colorants typically - organic substances. Pigments mostly - small variance minerals, although they can be either organic or inorganic. The incorporation of pigments in paints is the main method of controlling the properties of decorative coatings - color and opacity (opacity). Opacifying pigment in the pigmented material if its refractive index above the refractive index of the binder. The greater the difference in refractive index of the pigment and binder, the more coverage of the pigmented material. In addition, important form of the pigment particles, such as leaf shape of the particles of pigment gives more coverage than a needle or spherical.

Binder. Problem binder glue colorant to the surface of the printed product. Depend on the properties of the binder: paint adhesion with the printed material, methods of drying, light fastness, the height of the paint layer, gloss, abrasion resistance. The basis of the binder usually is the resin with a solvent which is responsible for the consistency of the ink until it dries.

Solvents. Enable the mixture of resin and pigment move to the surface during tompopechati. Tampon printing requires fast evaporating solvents for paints predachi. Besides the use of "fast" solvent enables multicolour print "on the wet crude".

Additives. To improve the properties of the ink, there are various additives. These include plasticizers and surfactants, to improve the elasticity by paint, pigment stabilization or other characteristics important for tampon. Without them, the paint will suffer defects such as brittleness, low strength of the paint layer, the separation of pigment and poor coverage.

Listed below are the main types of them.

Solvents, inhibitors - reduce the viscosity of the ink and its rate of drying.

Flow improvers - improve spreading paint on the print, reduce the formation of fine bubbles.

Antistatic - improve the electrical conductivity of the paint, reduce the accumulation of static electricity, reduce static spatter.

Hardeners and catalysts - improve paint adhesion to difficult materials.

Matting agent, makes the paint more opaque.

Pigments, opaque toothpaste - color additives that increase the aperture ratio (saturation) and covering power of paint.

Incorrect use of additives can worsen the properties of the paint. Therefore always strictly follow the manufacturer's recommendations paint.

 

Basic parameters of paint.

 

Type of binder. Depend on the type of binder printing, maintenance and paint adhesion properties.

Drying method (natural drying, R (convection), IR (infra-red radiation), UV (ultra violet radiation). From drying process depends on the rate of drying and its adhesion to the printing material.

Degree of opacity (transparent, translucent, polukroyuschaya, the coating, the coating super). Degree of opacity shows how tightly the paint layer can close the dark color of the printing material. If you print a transparent paint to black, the color of the paint will not be seen. If the paint polukroyuschaya, the paint color is dirty because of the color of the illuminated substrate. Super opaque paints can maximize tightly black.

Height paint (low, medium, high). Height paint indicates how thick the paint layer remains after it is completely dry (relief print).

Gloss Level (paint super matte, matte, velvety matte, glossy, super glossy). Gloss paint shows how much ink layer can reflect or scatter light.

Length paint (short, long). This ability to paint or tear tensile stretch. Depends on the cohesion of the binder.

 

Properties for pad printing inks.

 

Tampon paint should be long and have low thixotropic properties. The longer the paint, the more it moves on the surface of the tampon product. The lower thixotropic properties, the sharper will be the edge of the print.

Long paint. This ability of the paint to stretch under tension. If you try to take a long spatula of paint cans, over the spatula should reach long filaments, indicating a strong cohesion.

Thixotropic properties. In pad printing inks should have a low thixotropic property. When pressure tampon paint should not become more fluid and squeezed out of cliches.

 

Types of paint.

 

Colorful systems used in the production currently can be divided into six different categories, namely:

1. paint work by solvent evaporation;

2. oxide curing;

3. reagent (i.e. curing catalyst, the two components);

4. UV curing;

5. sublimation;

6. termokraski for ceramics and glass.

 

1. Solvent-based paints.

Solvent-based paints dominated in pad printing. They dry very quickly by evaporation of the solvent for many plastics. The easiest way to check the suitability of the solvent-based paint for a particular plastic - drop a solvent which is used in the dye dilution in the surface of the material. If the solvent melts the plastic, there is every reason to believe that the paint adheres to the surface very well.

 

2. Oxidative curing paint.

This type of paint is fixed on the surface of the printed product due to the interaction of the pitch, which is part of the paint, the oxygen in the air. Pad paint oxidation curing used in pad printing relatively rare because of the slow speed of drying, but they are excellent for tampon printing on metal and glass.

 

3. Two-component paint.

Two-component paints also contain resins, capable of curing. But the need for catalyst (hardener) should be added to the ink immediately before printing. The paint is fixed on the flap surface by means of interaction with hardener binding paints. In this method of fixing the paint is done in two stages. On the first paint is fixed by evaporation the solvent, the final durability of the paint layer is not achieved (from a few seconds to several minutes). At the second stage, the paint is fixed by the chemical interaction of hardener with binding paints, thus reached the final durability of the paint layer (from several hours up to 2-4 days). Heat treatment significantly reduces the time of polymerization. Another important factor is after printing the temperature printed paint layer must not fall below 15 degrees. If this happens, the process of polymerization (curing) will be stopped.

As the name implies, this paint is made up of two components: the paint and hardener (catalyst). Before printing, paint and hardener are mixed in the ratio specified by the manufacturer of paints. From this point, the polymerization reaction begins. Time for the viability determined by the printing ink, it is generally about 8 hours and is called "pot life." Depending on the ambient temperature and a series of colors, this period may vary from 4 to 12 hours. Be particularly accurate when mixing paint with the hardener. Careless mixing of two-component paint can give uneven adhesion and other phenomena in the form of voids, etc.

The main scope of the bicomponent tampokrasok if you want good resistance to chemicals and abrasion resistance, is pad printing on difficult surfaces such as metals, some types of plastics, glass and painted surfaces.

 

4. UV-curable inks.

Since the UV inks have the solvents do not rely on evaporation of the solvents in the printing process, as with conventional paints.

But, nevertheless, manufacturers achieve the desired tackiness to the pad printing. When the etching depth for the UV ink pad about 20 microns, about 6 microns only adheres to the tampon. But since UV inks do not contain volatile liquids, colorful layer in this case is much more dense than conventional crude layer of paint colors. UV inks contain a colorant in addition to a monomer and a photoinitiator. Curing of ink occurs only under ultraviolet light. For printers significant advantage UV tampon printing technology is that small changes occurring to the environment will not affect the paint, thereby providing much greater process stability.

 

5. Sublimation inks.

Tampon sublimation inks involved in a particular process, wherein the solids circulating in the gaseous state when heated. When these paints are applied on a suitable surface and then heated to a certain temperature (about 200?C) in the ink dyes are sublimated, it becomes porous material surface and the ink penetrates into the material. This significantly changes the color of the printed material. Once the material is cooled in the sealed paint surface. Pad printing - suitable for sublimation process as the transfer of paint should be minimized to prevent migration of the pigment color. Substrates can be keyboard and other products where resistance is extremely important to wear a sealed product. Colours tampons sublimation inks and limited selection of Pantone colors is practically impossible. Another limitation to the application of the sublimation dyes of the tampon is that the surface must be a color lighter than the color inks.

 

6. Termokraski for glass and ceramics.

Termokraski used for printing on glass and ceramics, under normal conditions in the solid state. Before applying termokrasku be heated to a liquid state. Termokraski become liquid when the temperature rises to 80 C. Printing equipment used for pad printing, pad heats and colorful tanks. Unlike conventional paints wet tampon tampon is not due to solvent evaporation, and because of the cooling effect when the tampon is in contact with the paint in the recesses of a cliche. The paint is transmitted from the surface of the tampon, since the outer layer of paint is still tacky, the paint which is on the surface of the tampon. The cooling effect further creates the opportunity for complete ink transfer. Pad printing process allows us to transfer termokraskami pretty much ink in the printing process, as depth of cliche in this case more - from 30 to 50 microns. After printing products are fired, for glass at about 580?C, ceramics - 1200?C. Products termokraskoy sealed pad should not be washed in the dishwasher.

 

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