Creation and regeneration of screen printing forms

 

Tension screen mesh on the frame.

 

Preparation of screen frame.

 

1. Purification of the frame and an emulsion paint is made by using special solvents and washes.

2. Remove residual adhesive from the frame is made with the sanding belt machine. If the adhesive is on the entire surface uniformly frame, the operation may not be performed.

3. Roughening. This operation is carried out with the new frames. Roughness of the frame can be given by using sandblasting or grinding machines. Sandblasting increases the surface area of the pasted 100-150%. What respectively 2-3 times increase bonding strength.

4. Deburring and rounding corners. Presence frame sharp corners and burrs may lead to rupture in tension or in operation. After removal of the adhesive or giving it rough to the touch, check the stripped surface and corners of the frame to the absence of sharp edges and burrs faces. If any, they need to clean up with sandpaper grit medium (№ 10 - № 20).

5. Degreasing frame. Degreasing the frame, you need to apply degreaser HT-9 or A9 extra. It is also used for degreasing nets. Degreaser applied with a brush and washed off with plenty of water until the foam has come. When using other degreasers, solvents such atsenton, № 646 usually on a rag which produce oil and degreasing are fat deposits that do not mean to degreasing. The quality of degreasing depends fly off the grid or not.

6. Drying frame. After degreasing and washing of the frame should be thoroughly dried by hot air or infrared radiation. Presence of moisture in the frame may result in peeling of the printing screen. Not allowed to touch the degreased surface.

 

The tension of the printing screen.

 

1. Selection screen. Screen mesh is chosen based on the tasks that must be addressed when printing. This resolution (print subtle elements), coverage (what a coat of paint, we need to print), run length (the maximum number of prints).

2. Tension at right angles. Standard installation frame at right angles to the direction of the filaments sieve. The size of the printing screen choose equal length frames plus allowance on all sides by the tensioner. In our videos allowance is 100 mm. (each side). Example: if the frame has an outer size 500x600 mm., This case, the grid will need 700x800 mm.

3. Setting the frame in the tensioner. When installing the frame in the tensioning device must verify that the upper surface of the frame was 2-3 mm above the bottom of the clip. This ensures adherence to the sieve frame with tension. If the screen does not lie, it will not contact adhesive to the frame, respectively, the grid is not glued to the frame.

4. Position accuracy control in the direction of screen grid provided with a filament by drawing a marker line, which should be parallel to the side of the sieve. In the course of this line tension should not be twisted. If the deformity will be present, upon receipt of bitmaps we may encounter moire.

5. Installing sieve transverse clamps. Cross-clamp is the one that pulls the screen in the direction perpendicular to the movement of the doctor blade. During installation, you need to ensure that the clips in the frame rested on rollers, clips along the same lines and were docked at the ends. In the process of fixing the screen need to try that it did not move relative to the clamp.

6. Installation sieves longitudinal clips. Longitudinal clamp is the one who pulls the grid in the direction of the squeegee. During installation, you need to ensure that the clips in the frame rested on rollers and lower terminals along the same lines and were docked at the ends. In the process of fixing the screen need to try that it did not move relative to the clamp.

7. Choosing the tensile force occurs sieve manufacturer's recommendations. Tensile force depends on the number grid, filament diameter and material.

8. Tension setting. In the tension of the tensioner sieve set using gear that regulate the pressure in the cylinders. Therefore, to adjust the tension force is necessary to use a strain gauge.

9. Stretch mesh. At the beginning of the grid need to stretch in the longitudinal (along the squeegee) direction. After stretching in the longitudinal direction produce a tension in the transverse direction. Tensioning force in the transverse and the longitudinal direction is controlled by using a strain gauge.

10. Stabilization of grids. Print high-precision products (electronic boards, measuring scales, etc.) should be given sieve to stand for 1-2 hours. During this time the screen stabilizes (stops to stretch). For the standard works which do not require very high precision stabilization time can be reduced to 30 minutes.

11. And contacting the mesh of the frame. To ensure contact with the surface of the screen frame put loads on the perimeter in the places where poor contact. Loads need to put a short distance from the frame so as not to interfere with applying the glue. If you put it closer to the center, then after removing the pressure in the sieve clamping force may fall.

 

Sticking to the grid frame.

 

1. Preparation of adhesive. Spread the glue KIWOBOND 1000 HMT according to instructions. When mixing the adhesive and hardener accurately follow the recommended proportions. If you violate proportions adhesive or hardener, adhesion is not stable. Gluing printing screens with high resolution can use diluent.

2. Application of the adhesive. Glue is applied to the printing frame with a brush with short bristles. Glue is rubbed into the grid, thus no need to control the air bubbles between the grid and the frame.

3. Drying of the glue. Glue drying time depends on the room temperature and ventilation. When using glue KIWOBOND 1000 HMT 20-30 min. You can already remove the tensile force at 20C. However, a complete cure and chemical resistance acquisition, usually occurs within 24 hours. You can not make an impact on the glue solvent to 24 hours. If selected, the screen got glue, it can be gently cleaned in acetone or solvent 646. With the proper observance of technology after removing the tension, the tension of the grid falls by approximately 5-10%.

4. Pruning sieve. With a sharp knife, trim the edges of the frame in a sieve on its perimeter. Be careful and attentive not to cut the screen and hands.

 

Stages of the stencil.

 

Degreasing mesh screen.

 

1. Selecting a degreaser. Degreasing must be done by specialized drugs intended for screen printing or HT -9 A9 extra. When applying household chemicals, possibly clogging due to high numbers sieve dispersed structure of certain drugs. Granular detergents, cleaning pastes, detergents, etc., can reduce the flexibility and elasticity of the sieve by using various bases and peroxides. Saving on brand-name drugs, you can lose in term of operation screens and incur an additional financial and time costs of its constriction. At an average circulation of 500 copies and proper handling of sieves, a stencil can be reused 25-30 times.

2. Applying a degreaser. Moisten with water and squeegee the stencil and PCB side. This is done in a simpler and more economical application of degreasing agents. Apply some amount of degreaser on the grid and carefully distribute the resulting foam on both sides with a brush. Thus dirt and fats are emulsified and become water-soluble. Brush should not be rigid (hard bristles can damage the filament nets) and should only be used for degreasing.

3. Remover degreaser. Degreaser need to rinse thoroughly until no more water until foaming, and the remains of degreaser are not visible. Rinse with degreaser, you can use high-pressure pump or shower.

4. Drying screen form. To speed up the drying can remove excess water using a vacuum cleaner or a porous synthetic cloth. You can also put a frame vertically on the long side and let the water drain out. Final drying is carried out in an oven with a stream of warm air (30-40C). If the temperature is high, it may weaken the force of tension. Do not allow drying of nets in a dirty and dusty, and the need to follow the lack of dust in the air stream. Dust sieve lead to uneven application of the emulsion, the presence of bright spots on the emulsions after drying.

 

Applying emulsion.

 

1. Control of drying. Check the absence of moisture and drops on the printing screen and the frame. If moisture is present, in this case, repeat the drying process in the oven until dry screen form.

2. Purity control grid. Check the cleanliness of the screen of debris and dust. Dust on the grid leads to uneven deposition of the emulsion formation of light spots (fish eyes), and pinholes. If there is dust on the grid, then vacuum clean or wash it with water, followed by drying.

3. Selection of the emulsion. Select the type of emulsion. The emulsion is selected based on the following criteria:

a. Resistance to paints. For different types of paint (water, plastisol, solvent, etc.) need different emulsion.

b. Resolution. The higher the resolution of the emulsion, the finer details can be obtained on the stencil.

c. Solid particles. The larger the quantity of solid particles, the emulsion will shrink less after drying. Try to choose the emulsion with a high solids content.

d. The viscosity of the emulsion. The more viscous emulsion, especially for larger numbers of nets can be applied.

Recommended for all types of emulsion paints Azocol Z1, Azocol Poly-Plus S, Azocol Poly-Plus S-RX, Ceracop 2300.

4. Selection and control of the cell. Select the desired length cuvette. Amount of the emulsion which can push it depends on the radius of its edges. The larger the radius, the more the emulsion is forced through the mesh. Check the quality and purity of the cell edge. Availability faces and emulsion residues unacceptable.

5. Select a scheme application. When selecting circuit application need to know that the result depends on the radius of the cell edge. If a cell radius is small, and the other is large, in the case of the first emulsion layer is less than the second coating with the same circuits.

6. Drawing from the printing side. Application of the emulsion with the printed side of the grid do wetting and squeezing the air bubbles out of the coarse grid. Application is carried out at the frame upright and upward movement of the cuvette.

7. Applying emulsion with squeegee side. Drawing from the squeegee side emulsion do immediately after application with the printed side on crude fotemulsii. This results in the emulsion layer to the printed side. Application is carried out at the frame upright and upward movement of the cuvette.

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8. Drying the emulsion. After application, the photographic emulsion to dry in a horizontal position facing up squeegee. The drying temperature should not exceed 30°C. At high temperature drying emulsion may polymerize (zadubet) before the copying process. When printing water based inks drying should be more careful. Moisture remaining in the emulsion reduces the stencil plate run.

9. Additional applications. Additional applications emulsion after drying is done to align the print side or squeegee. Additional applications do when it is necessary.

a. Dry with a squeegee side. This application is done when you want the best squeegee glide on large grids. After each application of emulsion, stencil dry in a horizontal position squeegee side up. Application amount and drying depends on the amount of the cell. The larger the cell, the more depositions required for its alignment.

b. Dry with the printed side. This application is done when you want a little emulsion layer thickness, but its smooth surface with the printed side (printing fine lines, bitmaps). After each application of emulsion, stencil dry in a horizontal position with the printed side up. Application amount and drying depends on the amount of the cell. The larger the cell, the more depositions required for its alignment.

 

Installation of positive (imagesetter).

 

1. Checking dry emulsion. Emulsion must be thoroughly dried, should not be nedosushennyh water droplets of the emulsion and the frame.

2. Checking the dirt on the emulsion. In the emulsion should be free of dirt and dust.

3. Verification of the matte side. Positive (imagesetter) must be designed so that when mounted on the matte side of the stencil in contact with the photographic emulsion. For direct printing, matte side to read, print transfers can not be read. There are exceptions that come from the customer's requirements.

4. Checking the dirt and dust on the positive (imagesetter). On the positive (imagesetter) should not be dirt and dust. If it exists, then wipe gently with a positive spirit.

5. Checking black density. The density of the black portions to be positive for at least 3 units. This means that at lumen therethrough fluorescent light should not be visible.

6. Checking breakdowns. In dark areas of positive should not be transparent points. This can be checked on the lumen. If these are present and can retouch the black marker, but it is better to re-derive positive.

7. General recommendations for the location of the positive (imagesetter). Typically, each of the printing press there are requirements on the location of images for printing. But there are basic rules. Squeegee input field should not be larger than the field exit. The image must be located in the center of the frame along the course of Raquel. The larger field of input, output and end, the less distortion in the press, etc.

 

Exposure emulsion.

 

1. Purity control copier glass frame. If there is dust on the glass, dirt, paint and emulsion, all this will give breakdowns at the stencil, which would have to retouch the breakdown spot. And if the trial is in the bitmap, you have to redo the frame, otherwise the marriage will be in print.

2. Installing stencil copier frame. Put the frame with the printed side with a positive to the glass. Put the vacuum cord around the frame. Vacuum cord to ensure uniform vacuum around the perimeter of the stencil, thereby achieving maximum contact between the positive and the photographic emulsion (imagesetter). Close to include a frame and the vacuum pump. Ensure complete evacuation of air from the copier frame. If vakuumatsiya quality, vacuum tire fits completely inside corners of the frame.

3. Set the distance from the lamp to copy the frame. The distance depends on the quality of the copy of fine lines and exposure time. The greater the distance, the better quality and more time. The shorter the distance, the lower the quality, but less time. Minimum distance should not be less than positive diagonal copied. With increasing distance time varies with the square of distance.

4. Set during copying. Copy time may be determined by stepwise exposure. It uses filters Kiwo ExpoCheck. It consists of three films, permitting a single 9-step gray-film filter. This combination allows to determine not only the optimal time and the exposure time of admission, but also the willingness to fulfill any print job using any grid.

Parameters affecting the exposure time:

Number sieves (the larger the screen, the greater the exposure time).

Color screen (colored mesh increases the 1.5-2 times).

Emulsion layer thickness (the thicker the layer, the longer the exposure time).

Lamp life (the longer the lamp works, the greater the exposure time).

5. Exposure image. During exposure occurs overexposed those portions of the emulsion on the grid, which are not covered with black layer positive (imagesetter). In the process of copying light axis must be perpendicular to the glass frame. After the time copying relieve vacuum, open the frame and remove the stencil shape.

 

Film development stencil.

 

1. Emulsion remover is not illuminated. Dampen a photographic emulsion with warm water and squeegee printing side. Let stand 1-3 minutes emulsion (emulsion should absorb moisture). The thicker the layer of emulsion, the longer it needs to soak.

2. Flushing under pressure. Rinse off under pressure is not overexposed photo emulsion is only necessary because the printed side with the squeegee side is easier to wash overexposed emulsion. Carefully. When film development pressure better washed most subtle details and bitmap images. The distance by washing is not less than 15 cm.

3. Flushing sotto pressione. Emulsione fotografica Risciacquare sotto pressione non e sovraesposta e necessario solo perche il lato stampato con il lato seccatoio e piu facile da lavare emulsione sovraesposta. Attenzione. Quando la pressione sviluppo di pellicole lavato meglio dettagli piu sottili e immagini bitmap. La distanza dal lavaggio non e inferiore a 15 cm.

4. Drying screen form. Final drying is carried out in an oven using a stream of warm air (30-40°C).

 

Finishing stencil.

 

1. Supplementary lighting stencil. To increase the stencil plate run, and water resistance can be added to light the squeegee side for 10-20 minutes. Supplementary lighting must be done for large print runs and print when using water colors.

2. Zadublivanie emulsion. For large print runs of 10,000 prints mainly for water-based paints, it makes sense zadubit photographic emulsion using hardener KIWOSET K. As a result of this operation is greatly increased its run length, but after printing emulsion is not regenerated, becomes irreversible.

3. Retouching stencil. If you keep a clean production process and watch the glass copying frames, retouch holes on the emulsion is not necessary. This operation make if on the field of study there are openings (holes) through which they may leak paint, and along the edges of the printed photoemulsion. For this you need to select the correct type retouching (for water paints or for solvent and UV). Retouch need with the printed side thin layer. The most ideal way to put retouching flush with the emulsion. This can reduce the viscosity of retouching. After applying retouching dried in a drying cabinet.

For these works suggest the following retouching: Kiwofiller 407 Red, Kiwofiller 408 Green, Kiwofiller WR 01.

 

Regeneration screen form.

 

1. Purity control stencil paint. Screen form before regeneration must be purified from the remnants of paint and tape.

2. Preparing otslaivatelya emulsion. To peel the emulsion used aqueous solutions of drugs Pregasol EP3, Pregasol Tabs, which are bred with warm water. Also there are ready solutions Pregasol F, Pregasol P.

3. Cleaning of paint residues. This operation reduces the amount of colorful spots and improves the process of peeling emulsion.

a. For plastisol inks before regeneration is necessary to put on a photographic emulsion on both sides alkali PREGAN PASTE no more than 5 minutes. Thereafter, the shower rinse, and then treat high blood pressure. This operation clears the net from the remnants of paint and peeling easier.

b. For solvent and UV inks before regeneration is necessary to put on a photographic emulsion on both sides alkali PREGAN 244E for 10-15 minutes. This potent solvent cleans paint residues, but does not destroy the photographic emulsion. Washed molding.

4. Emulsion remover.

a. Apply a wash emulsion with a printed and squeegee side with a brush.

b. Rub the brush layer of emulsion with the printed side. Let stand in a horizontal position stencil printed side up. Do not leave more than 15-20 minutes a frame coated otslaivaetelem otherwise dried up wash emulsion will be very problematic.

c. Rinse off with water emulsion under high pressure squeegee side at a distance of 10-15 cm.

Emulsion bad exfoliate:

Applied the wrong cleaner that it Poddube. Photo emulsion for water-based paints can not be processed by solvent cleaners.

Emulsion was nedosvechena and zadubilas potsesse in print.

Oslaivatel overdone on the emulsion more time required.

5. Cleaning phantom images. Phantom of this paint residues in the form of a thin layer in the open field sieve. Visually you see a pale shadow on the sieve from previous printed images. The presence of phantoms reduces the adhesion of emulsion with a sieve, but also affect the uniformity of application of the paint layer when printing. Sometimes you can see on the new imprint the presence of parasitic images from previous orders, especially when using a high number of sieves. For the rapid removal of these images is applied chemistry, PREGAN PASTA + PREGAN COMBI-CLEAN. First applied the first component PREGAN PASTE after him just right to put the second component PREGAN COMBI-CLEAN.

The resulting mixture was triturated brushed uniformly across the surface of the printed grid and the squeegee side and allowed to stand for 10-15 minutes and plastisol inks solvent and 15-20 minutes for UV inks. After holding the stencil shower and washed under pressure.

6. Deep chemical cleaning stencil applies when the phantoms and the remains of emulsion does not wash off in faster method. Also from various chemical reactions can stay remains of emulsion, which are not washed standard products and prevent the passage of paint through a sieve. This usually occurs because of an incorrect copy of emulsion (emulsion not posvecena), violations of the technology for preparation of paints and paint wash with stencil (incompatible with emulsion paints, thinners, solvents and additives that are not recommended by the manufacturer), no regeneration of the high pressure pump. Categorically it is impossible to apply with many emulsions such as solvents (№646 650, Acetone), savings on solvent leads to the loss of a sieve, and this, as a rule, always more expensive and the Finance and time.

To remove these images applied chemistry Pregan Anti-Ghost Extra. This drug does not have a strong impact on the grid.

 

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