Screen printing rickets analysis

Screen printing rickets analysis

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In the printing production process, due to the influence of printing platen, screen plate, scraper, paint printing paste, squeegee operation and post-treatment, it is easy to cause printing defects on the fabric, which affects the appearance of the product. Reduce economic efficiency. The following is a description of the common defects in the patterning of knitted underwear fabrics and the main reasons for the analysis.

1. Inaccurate flowers (wrong version, inaccurate pattern, wrong flower)

Patterns of two or more colors, one or several patterns of all or part of the pattern on the printed fabric are unraveled or crushed, and are not printed on the position to be printed, which is inconsistent with the pattern standard, and is called Not sure about the flowers.

Reason: 1 The printing plate and the positioner on the printing table or the printing machine have too large clearance. When the positioner on the printing plate is loose, the force generated by the running of the squeegee and the plate makes the printing plate move in the direction of strong force. The pattern is not printed. Printed location. 2 The printing frame is deformed and the screen attached to the frame is partially loosened or disengaged, so that the partial pattern on the plate is moved away from the original position. 3 The degree of dryness and wetness of each printing plate in a pattern is quite different, the layout with high humidity is loose or partially loose, and the pattern of the plate moves in the direction of force when the blade is running, and the pattern on the fabric is partially Or all degrees of misalignment occur. 4 During the operation of the printing plate, the printed piece or cloth is moved to move the printed pattern on the printing table. 5 The screen tensions of the various printing plates are quite different or uneven, and the layout patterns with small or uneven screen tension are easily displaced when affected by temperature and humidity.

2. Permeation (diffusion, bleed)

The contour edge of one or several color patterns on the fabric spreads outward, and all or part of the edge of the pattern forms a rough color edge with the same color and light color, and the two different color patterns are connected or adjacent to each other. A third hue will appear, a phenomenon known as percolation.

Reasons: 1 In the paint printing paste, the content of thickener is insufficient or the amount of water is too much, and the consistency of the printing paste does not meet the requirements. Due to the faster flow speed of the printing paste, the pattern colorant on the fabric flows more than the edge of the pattern, and the pattern outline is unclear. 2 When printing, the speed of the squeegee is slow, the pressure is high, the amount of slurry is large, and the number of round trips is frequent, etc., the amount of the pattern is too much, because the amount of the fabric is more than the amount of the fabric, the color paste will bleed outside the pattern. . 3 When the pattern area is large and the fabric has a large amount of pulp, the printed fabric is stacked for a long time to increase the humidity of the fabric, and the pattern colorant is easily spread out. 4 When the printing paste is prepared, the mixing is uneven or the printing paste is directly diluted with water, which affects or destroys the stability of the printing paste in the emulsified state. 5 When the synthetic fiber fabric, the synthetic fiber is printed on the blended or interwoven fabric of the natural fiber, since the synthetic fiber is hydrophobic, the printing paste is easily bleed out to the pattern. 6 The tissue is sparsely thin, the suctioning ability is small, and it is particularly sensitive to the amount of slurry. When the amount of colorant is slightly more, it is easy to seep.

3. Outcrop (dry version)

The pattern on the fabric did not get enough color paste, and the color was light and unclear. The phenomenon that the bottom color or fine pattern of the fabric was broken was called the bottom.

Reason: 1 Due to the deformation of the frame, the layout is lifted, leaving the fabric laid on the table, so that some of the patterns are insufficient (even de-slurry). 2 When the scraper is running fast, the pressure is small, the amount of slurry is insufficient, the scraper rubber is too hard, and the cutting edge is too sharp, etc., and the pattern is easily insufficient. 3 patterns, part of the mesh blockage and the color paste is too thick, so that the color paste over-net rate is reduced, and the pattern on the fabric is insufficient. 4 Thick fabrics with thicker or sparse textures. Because the surface of the fabric is uneven, the concave portion is prone to insufficient pulp. 5 The printing pad is partially low-lying or the unevenness of the printing pad makes the pattern on the fabric insufficient. 6 The severe wrinkles of the fabric are not fully unfolded on the printing table, or severe wrinkles are caused when the cloth is applied. When the printing is folded, the inner side of the wrinkles and the sides of the raised wrinkles cannot obtain the color paste, and the background color of the fabric is exposed.

4. Color difference

The difference between the color of a certain pattern on a printed fabric and the color of the process standard or the color of a certain pattern on the printed fabric is called the color difference. Chromatic aberration is a combined result of differences in hue, brightness, and purity.

Reason: 1 The color tone, color shade, color saturation, etc. of the paint paste used do not match the production process requirements. 2 Weighing the coating is not accurate when preparing the printing paste. 3 There are different color residual pastes in the container containing the printing paste. 4 The consistency of the printing paste, the density of the fabric, the thickness, the humidity, the speed of the running of the scraper during printing, the pressure, the amount of the pulp, etc., all affect the color, brightness and purity of the pattern on the fabric.

5. The color of the pattern is uneven

The shades of the same color on the fabric are inconsistent, and when the pattern area is large, there is an irregular sheet-like or horizontal color file and a regular longitudinal color file, which is called uneven color shade.

Reason: 1 When the printing operation, the speed and pressure of the squeegee operation are inconsistent or the slurry is uneven, so that the amount of the sizing of the pattern is relatively small, and the pattern of the fabric with a large amount of pulp is darker. 2 When the running scraper is bouncing or slightly raised, the residual color paste on the pattern on the plate passes through the mesh to the fabric, resulting in a darker horizontal color. 3 The edge of the rubber scraper is not flat, and the pressure and the amount of the slurry are not uniform when the printing is performed, so that the pattern on the fabric presents a regular, vertical and inconsistent longitudinal color. 4 The partial depression or the printing plate layout of the printing table is far away from the fabric on the printing table, and the pattern is insufficient for the pulp and the color is light.

6. Reprint (ghost, double shadow, double print)

Part or all of the pattern in the pattern on the fabric presents a double image called a ghost image. Small area patterns and thin lines are easy to produce and more obvious.

Reason: 1 The artificial leather or plastic cloth on the surface of the printing table is thin or not tight, and the pressure of the squeegee is high during operation. The artificial leather or plastic cloth is slacked before the cutting edge in the running direction of the squeegee, and is laid on the printing table. The fabric is also moved so that the pattern is not printed in the position corresponding to the printed pattern, resulting in a double pattern. 2 When the printing plate is loose or severely loose, the running pressure of the scraper is slightly larger, the front plate of the cutting edge in the running direction of the scraper is slackened, the pattern on the plate is displaced, and the pattern printed on the fabric is printed. A double image is formed. 3 When the printing is used, the positioning device with the alignment function is too large or the positioner is loose. When the squeegee is running, the printing plate is pushed, and the reciprocating operation of the squeegee causes the screen to be printed. 4 The pattern printed on the fabric is not clear, and when the film is printed again, the displacement of the fabric or the plate is easy to produce reprint.

7. Twilight

The pattern of a certain color on the printed fabric partially appears to be adjacent or adjacent to the pattern, and the same color, light and unclear pattern color block or color strip is called ochre.

Reason: 1 The height of the plate lifted from the pad is not enough. When one of the plates is detached and the other locator is not completely detached, the lateral movement of the plate licks the pattern on the fabric to the outside of the edge of the pattern. The 2 plates failed to enter the pad positioner vertically and accurately, and the residual color paste in the plate pattern mesh was hung on the fabric outside the pattern position. 3 When the amount of pulp on the fabric is too large or the back side of the printing plate (contact surface with the fabric) has too much paste color on the edge of the pattern, the improper lifting and lowering of the printing plate is most likely to cause ochre.

8. Splash color (splashing, flying)

On the printed fabric, a phenomenon that there is no regular distribution and no certain size of color paste dots (ellipse when the color point is large) is called splash color.

Reasons: 1 When the scraper is running, the pressure is small or the fabric suction ability is poor. When there is more color paste remaining in the plate pattern mesh, if the surface of the printing table is more viscous, or the printing plate is loose, or the printing plate If the running speed is too fast, the color paste in the mesh will be splashed on the fabric due to the viscoelastic jump of the layout. 2 When printing a wide horizontal strip pattern, the blade will jump up and down during the running of the stencil, and it is easy to splash the excellent pulp from the blade edge and fly on the fabric of the plate. 3 Scraper runs too fast on the plate, and it is easy to produce splash when the paste viscosity is low.

9. Color point

The pattern on the printed fabric, irregularly showing small dots or small thin lines, called color points.

Reason: 1 When the printing paste is prepared, the paint paste is not fully dissolved, and the screen mesh of the printing paste is too large or the extrusion force is too large, so that the coating particles which are not dissolved are distributed through the mesh. In the paste. The color paste is printed on the fabric, and many small color spots with darker shades appear in the pattern portion, and the smaller paint particles which are not dissolved when the printing paste is stirred form a fine dark line. 2 The paint printing paste has a long time and has precipitated, and some of the paint particles that are formed together will also have a color point phenomenon when the color paste is printed on the fabric.

10. Flower shape deformation (proofing) The flower shape on the fabric has obvious deformation compared with the original pattern, which is called deformation or aliasing. The most obvious is when printing horizontal lines and geometric patterns on the piece.

Reason: 1 When the surface of the printing table is relatively sticky and the piece is hand-laid, the piece of clothing is greatly deformed due to uneven force. The piece removed from the printing pad after printing has a certain shape recovery, and the flower on the fabric The pattern is deformed as the shape of the piece is restored. 2 The surface of the printing table is too sticky. When the film is printed, the force is relatively large, so that the fabric is elongated more and the recovery degree is smaller. Because the piece is deformed, the pattern is also deformed along with the piece. 3 The printing frame is deformed or the mesh and the frame are not firmly adhered to make the partial layout loose, which causes the pattern on the plate to be deformed.

11. Printed marks, trachoma

On the printed fabric, there are regular color blocks and small color points on the outside of the pattern, which is called the print mark or the blisters. These color patches and fine color dots appear in the same position on the piece of clothing, appearing regularly on the cloth, and the pitch is equal to the running pitch of the plate.

Reason: 1 The part of the printing plate is scratched or has a through hole after being repaired. When the sealing net is not strong, there are sand holes on the printing film. When the printing is performed, the color paste passes through the through holes and is on the fabric. On, the version of the print is printed. There are small through holes on the plate other than the plate pattern. When the film is printed, the color paste passes through the small holes, and the corresponding small color points appear on the group, which is called “sand eye”. The production of sand holes is mainly caused by unclean screens, dirt or large dust on the glass of the platen, insufficient exposure time, and too thin coating of the photoresist. The operation of the scraper causes the sand to be worn.

12. Color transfer

On a printed fabric composed of a plurality of colors, one or several patterns of colors do not match the color of the pattern printing paste, and have a distinct color difference, which is called color transfer.

Reason: 1 When the patterns of two different colors are connected, the area of the first printed pattern is larger and more pulp is applied, so that the pattern is permeated or stacked on the fabric, and the printed version after printing is pressed. The color paste first printed on the fabric enters the plate through the plate mesh, causing the color paste in the post-printing plate to change color. 2 In the printing process, serious “edge pollution” occurs, so that more color paste is stacked on the printing table outside the edge of the fabric or the edge of the fabric. When the printed pattern is attached or adjacent to it, the color paste passes through the pattern net. The hole enters the plate to discolor the color paste. When the printing plate is changed to a color paste of different hue, an undried color paste remains in the gap of the plate or the scraper. When the scraper is running, the residual color paste is mixed into the color paste of the plate to discolor the color paste.

13. The pattern position is not allowed

The position of the individual pattern on the piece of clothing does not match the production requirements, which is called the position of the pattern is not allowed.

Reason: The location of the patch on the printing table is not accurate.

14. Wrinkle and lack of flowers

The pattern of the wrinkled portion of the printed fabric is incomplete.

Reason: 1 The fabric before printing has severe wrinkles. When the fabric is laid on the printing table, the folded wrinkles are not spread out flatly, and the wrinkled portion cannot be printed on the printing. 2 When laying on the printing table, if the table top is more sticky, the fabric is thinner, and if the operation is inadvertent, a wrinkle print will also occur.

15. Unacceptable flowers

The continuous pattern on the piece of cloth does not regularly show a continuous pattern of defects, which is called inaccurate flower arrangement. It is expressed as a horizontal (pitch latitude) gap or pattern overlap (produced by hand printing).

Reason: The printing position between each piece of cloth on the printing table is not accurate. If the front end of the next piece of cloth exceeds the printing position, the piece of cloth that exceeds the printing position will not be printed with a pattern, resulting in a neutral phenomenon; If the front end of the next piece of cloth is not laid on the printing position on the printing pad, the back end of the printed piece of the front piece will be overlapped and printed again.

16. Border pollution

Continuous pattern or individual pattern, and requires one or several color patterns to be printed on the printed fabric on the edge of the piece. The pattern on the edge of the fabric is severely permeated, causing the pattern to be blurred or the pattern is deformed. If the patterns of two different colors are connected or adjacent to each other, the phenomenon that the third color will appear is called edge staining.

Reason: 1 is the occlusion pattern and the paper stuck under the printing plate (the contact surface with the fabric) is far from the edge of the fabric, that is, there is a hollow pattern outside the edge of the fabric, and the pattern color outside the edge of the fabric when the squeegee is running. The pulp is stacked on the printing pad. If the color paste is continuous with the fabric, the fabric will permeate. If it is pressed by the printing plate, it will contaminate the fabric and make the pattern blurred or even deformed. A third color is produced when connected or adjacent. 2 When the scraper runs in the plate, it stops at the pattern, which not only makes the partial fabric get too much pulp, but also causes the pattern to permeate, and at the same time, the edge of the piece will also accumulate color to cause edge staining.

17. White border

Continuous pattern or individual pattern, and requires one or several colors of the pattern should be printed on the printed fabric on the edge of the piece, showing the pattern is not printed on the edge of the fabric, and the width is not wide, called white side. Reason: 1 is the occlusion pattern and the paper attached to the underside of the printing plate is not positioned properly, so that some or all of the edges of the fabric are not printed. 2 The cloth laid on the pad is too wide or the piece is too small, and the edge of the fabric exceeds the plate pattern. 3 When the fabric is laid on the printing table, the position is shifted, so that the partial edge of the fabric exceeds the printing pattern, and the white border is not printed.

18. Color matching

The printed fabric is stained with irregularities, different sizes, different shapes of variegated or regular flower prints opposite to the flower shape, called color matching.

Reason: 1 After the printed fabric is removed from the printing table or suspended, the color paste and the fabric on the fabric are rubbed or touched with each other. 2 The printed fabric removed from the stamp pad is too thick for too long, and the pattern will be smudged on the surface of the fabric. 3 The pattern on the fabric is too much, and the flower area is large. When the cloth is printed by hand, there is no drying equipment on the printing table, which is easy to produce color.

In recent years, domestic manual printing has developed rapidly. It has the advantages of simple equipment, unlimited number of color registration, easy control of quality, and so on. This traditional printing method has been recognized and widely used.