The author's words: The author contacted textile printing from 1968. In 1974, he began to work on the printing process of knitwear (cut, ready-to-wear, crepe) at the Tangshan Knitting Factory. Due to the needs of the work, according to the printing of rickets samples collected from the workshop and the experience of printing production, in 1991, the author analyzed the "Causes of the cause of plaque in the printing of flat underwear coatings", in "Screen Printing", No. 2, 1992 Published, and widely spread and applied in the national knitting printing industry. In recent years, the author has repeatedly discovered that some people have stolen this article, for example: "Guangdong Printing" 2003 06, Wang Zhenhe published "Screen Screening Disease Analysis"; "Textile Printing" 2005, Issue 5, Wang Zhenhe published " "Screen printing disease analysis"; "Screen Printing Practical Handbook 2007 Edition" (China Printing and Packaging Network) published "Texture Screen Printing Failure Analysis"; "Screen Printing Industry" 2009, Issue 6, Lin Xiaowei published "Screen Printing" Rickets analysis" and so on. The author believes that the current technology, equipment, equipment and materials of China's garment printing industry are close to the international level, and the technical articles of the previous two decades have not been changed, which will be misleading to some readers. In order to thank many readers for their attention to this article, the author adapted the original text according to the actual situation of the current printing production.
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At present, China's printed garments are mainly made of cotton fiber fabrics, and there are also blended or interwoven fabrics of cotton fibers and chemical fibers. The fabrics are knitted and woven. In the white or light-colored fabric, the coating direct printing process is adopted, which has the advantages of short process flow, simple operation, bright color, complete chromatogram, easy color matching and clear outline of printed pattern, and more mainly because of the printed fabric. It can be baked. The partial pattern and the direction of the continuous pattern pattern printed with certain position requirements are mostly printed on the piece by the lithographic screen printing method. The continuous pattern joint has no pattern in a certain direction and can be flat on the crepe. printing.
The flat net paint printing method has two methods of mechanical and manual operation. In the printing production process, it is easy to be affected by factors such as printing platen, screen plate, scraper, paint printing paste, squeegee operation and post-treatment. Printing defects on the fabric, affecting the appearance of the product and reducing economic benefits. The following is a description of some of the common forms of rickets that are common in flat-screen paint printing and analyze the main causes.
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 fabric are separated or laminated. Not printed in the corresponding position, does not match the pattern standard.
Reasons: 1 When the positioner on the screen, printing table or printing machine is loose, the force generated by the blade running and the plate makes the screen move in the direction of strong force, the pattern is not printed in the corresponding position; 2 frame is deformed and pasted in the frame The screen has partial looseness or disengagement, which causes some patterns on the layout to move to the original position; 3 each screen version has a large difference in wetness and wetness, and the layout with high humidity is loose or partially loose. Seriously, when the scraper is running, the pattern of the layout is moved toward the running direction of the scraper, so that some or all of the patterns on the fabric are misaligned in different degrees; 4 during the running of the screen, the printed cut pieces or crepe are moved, so that Reprinted pattern shift; 5 screen mesh when the screen tension is uneven or the screen tension of each screen in a pattern is large, the screen tension is small or the partial screen tension of the screen Small, when screen printing, the screen is easy to shift due to the loose pattern of the layout; 6 the screen tension is not stable after 1-5 days of stretching, and the pattern of each screen will follow the tension of the screen. The change shifts the pattern.
2, permeation (diffusion, bleed): the contour edge of one or several color patterns on the fabric expands outward, and all or part of the edge of the pattern forms a rough color edge with the same color as the pattern color, two kinds A third hue occurs when the patterns of different colors are adjacent or in close proximity.
Reasons: 1 In the paint printing paste, the content of thickener is insufficient or the water is too much. The viscosity of the printing paste can not meet the application requirements. The flow of the printing paste on the fabric flows outside the edge of the pattern. More, the pattern outline is not clear; 2 when the printing operation, the speed of the blade is slow, the pressure is too large, the amount of slurry is too much, the number of times of squeegee is high, etc., the pattern will be too much pulp, because the fabric is more than the pulp. The amount of color paste will bleed outside the edge of the pattern; 3 when the pattern area is large and the amount of the fabric is too much, the pattern colorant is easy to spread outward; 4 when the printing paste is prepared, the mixing is uneven or the printing paste is directly diluted with water. Affects or destroys the stability of the printing paste in the emulsified state; 5 when the synthetic fiber fabric, synthetic fiber is more than the natural fiber blended or interwoven fabric printing, because the synthetic fiber is hydrophobic, the printing paste is easy to extravasate to the pattern 6; tissue sparse thin fabric, less suction capacity, the fabric is particularly sensitive to the amount of pulp, a little more pulp is prone to percolation.
3, the bottom of the bottom (dry version): the pattern on the fabric did not get enough color paste, the color is light and unclear, revealing the undertone or fine pattern of the fabric is broken.
Reasons: 1 Due to the deformation of the frame, the layout is lifted off the fabric laid on the printing table, so that some of the patterns are not enough pulp (even de-slurry); 2 the blade runs fast, the pressure is small, the amount of slurry is insufficient, the scraper The rubber is too hard, the blade edge is not straight and other factors are easy to make the pattern pulp insufficient; 3 pattern mesh hole blockage or color paste is too thick, so that the color paste permeability rate is reduced, the pattern on the fabric is insufficient; 4 yarn is thicker Thick tissue or uneven fabric, the concave part is easy to get the pulp shortage; 5 the printing table is uneven, the concave part makes the pattern on the fabric insufficient; 6 the serious wrinkles of the fabric are not on the printing table When it is completely unfolded, or the fabric is laid, it causes severe wrinkles. When printing, the inside 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. Chromatic aberration: the difference between the color of a certain pattern on the fabric and the standard or the color of a certain pattern; the color difference is a comprehensive result caused by the difference in hue, brightness and purity.
Reasons: 1 The hue, color and saturation of the paint are not in conformity with the color matching process requirements; 2 the coating is not accurate when preparing the printing paste; 3 the residual color paste of different colors in the container of the printing paste; 4 printing color The consistency of the pulp, the density and thickness of the fabric and the humidity, the speed and pressure of the blade running during printing, and the amount of pulp will affect the color, brightness and purity of the pattern on the fabric.
5, the shade 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.
Reasons: 1 When the printing operation, the speed and pressure of the blade are inconsistent or the unevenness of the slurry, so that the amount of the slurry is more or less, the pattern of the fabric with a large amount of pulp is darker; 2 the running blade is beating or slightly lifting At the beginning, the color paste remaining on the pattern on the plate penetrates through the mesh to the fabric, resulting in uneven color shades; 3 rubber scraper edge is not straight, and the pressure is not uniform when the blade is running. All of them make the pattern on the fabric appear regular, dark and inconsistent longitudinal color files; 4 the printing table is partially low-lying or the screen layout is far away from the fabric on the printing table, which will also cause the pattern to be insufficiently colored.
6. Reprinting (ghosting, double shadow, double printing): The pattern in the pattern on the fabric presents a double image partially or completely, and the small area pattern and fine lines are easy to produce and obvious.
Reasons: 1 The leather on the surface of the printing table is thin or not tight, the pressure is large when the blade is running, the leather is slackened at the front end in the running direction of the blade, and the fabric laid on the printing table is also moved, and the pattern after the printing is followed. The rebound of the leather is easy to produce a double pattern; 2 when the printing plate is slack or severely loose, the blade running pressure is slightly larger, the front end of the blade in the running direction of the blade is slack, and the pattern on the plate is shifted and printed. After the scraper runs, the plate rebounds to make the pattern printed on the fabric easy to form a double image; the positioner of the 3 screen, printing table or printing machine is loose, and the screen is pushed when the blade is running, resulting in the screen printing; 4 The pattern printed on the fabric is unclear, and when the film is printed again, the displacement of the fabric or plate is easy to produce reprinting.
7. Twilight: The pattern of a certain color on the fabric partially presents the same color, light and unclear pattern color block or color strip adjacent to or adjacent to the flower (occurring when printing by hand screen printing).
Reasons: 1 The height of the screen is not enough to lift from the printing table. The lateral movement of the screen will wrap the pattern on the fabric outside the edge of the pattern; 2 before the screen is not accurately positioned, the residual color paste in the screen pattern mesh is è¹On the fabric outside the pattern position; 3 when the amount of pulp on the fabric is too large, the screen printing surface (with the fabric contact surface) is stuck with the color paste outside the edge of the pattern, and the screen is lifted and lowered improperly, which is the most likely to cause ochre.
8. Splash color (splashing point, flying color): The printing fabric presents a color paste dot with no regular distribution and no certain size. When the color point is large, it is elliptical.
Reasons: 1 When the blade is running, the pressure is small or the pattern is insufficient, and more color paste remains in the mesh pattern mesh. If the screen plate touches the surface of the printing table with a large viscosity or the screen is lifted too fast when running. Both will splash the color paste in the mesh on the fabric due to the viscoelastic jump of the layout; 2 When printing a wider horizontal strip pattern, the blade will jump up and down when running on the plate, which is easy to splash from the blade. The pulp flies down on the fabric outside the plate; 3 the blade runs too fast on the plate and is also prone to splashing.
9. Color point: the pattern on the fabric, which irregularly presents small dots or small thin lines with excellent depth.
Reasons: 1 When the printing paste is prepared, the paint paste is not fully dissolved, 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 printing paste, when the color paste is printed on the fabric, many small color points with darker shades appear in the pattern portion, and the larger paint particles which are not dissolved when the printing paste is stirred form a fine dark line. 2 The prepared paint printing paste has a long standing time and has precipitated, and some of the coated paint particles will also have a color point phenomenon when the printing paste is printed on the fabric.
10, flower shape deformation (out of sample): the flower shape on the fabric has obvious deformation compared with the pattern, the most obvious when printing horizontal straight lines and geometric patterns.
Reasons: 1 The surface of the printing table is relatively sticky and the fabric is greatly deformed due to uneven force when the fabric is hand-laid. The fabric removed from the printing table after printing has a certain shape recovery, and the pattern is along with the shape of the fabric. Responsive and deformed; 2 The surface of the printing table is too sticky, and the force is large when the fabric is removed after printing, so that the fabric extends more and the recovery degree is smaller. Because the fabric is deformed, the pattern is also deformed with the fabric; 3 screen version frame The deformation or the adhesion between the screen and the frame is not strong enough to loosen the partial layout, causing the pattern on the layout to be deformed.
11. Printed marks and sand holes: regular color blocks and fine color points appear on the fabric outside the pattern. These color blocks and fine color spots appear on the fabric at the same position and appear regularly on the cloth. The spacing is equal to the running distance of the plate.
Reasons: 1 The screen version of the screen pattern is damaged or repaired. There is also a hollowed out place. When the film is printed, the color paste is printed on the fabric through the screen and presents a print mark. 2 The outer part of the screen pattern is hollowed out. Small pinholes, when printing, the printing paste passes through the small holes, and presents corresponding small color spots on the fabric. It is commonly called “sand eyeâ€. The generated sand holes are mainly unclean when making plates, and there are dirt on the glass when printing. Or because of large dust, insufficient exposure time, and too thin coating of the photoresist, the operation of the scraper will cause the sand to be worn.
12. Color transfer: On the printed fabric composed of a variety of colors, the color of one or several patterns does not match the color of the printed color paste, and there is obvious color difference.
Reasons: 1 When the patterns of two different colors are adjacent, the size of the first printed screen pattern is larger and more pulp is applied, so that the pattern is seriously permeated or more printing paste is accumulated on the pattern, and the screen printing after printing is performed. When pressed, the color paste first printed on the fabric enters the plate through the plate mesh, causing discoloration of the color paste in the post-printing screen; 2 severe "side stain" during the printing process, so that the edge of the fabric or More printing paste is deposited on the printing table outside the edge of the fabric. When the post-printing screen pattern is adjacent or adjacent to it, the color paste enters the plate through the pattern mesh to change the color paste; 3 screen version is replaced. When the color pastes of different colors are left, the undried color paste remains in the gap of the plate or the blade. When the blade is running, the residual color paste is mixed into the printing paste of the plate to change the color of the printing paste.
13. The position of the flower pattern is not allowed: the position of the individual pattern on the fabric does not match the production requirements.
Reason: The location of the fabric on the printing table is not accurate.
14, folds and lack of flowers: printed fabrics in the folds of the pattern is incomplete.
Reason: 1The fabric before the printing has severe wrinkles. When the fabric is laid on the printing table, the folded pleats are not spread out flatly. The parts wrapped by the pleats during printing cannot be printed. 2 When laying the fabric on the printing table If the table top is relatively sticky and the fabric is thin, wrinkles may occur when the table is inadvertently operated, and flower shortage may occur in the wrinkles.
Let's talk about "analysis of the causes of sputum in flat screen paint printing"