Common defects of the hottest printing products 4

Common defects of printing products

defects caused by two-color paste

1. Eye circles

⑴ form: on the cloth surface of discharge printing, the pattern edge presents undue white circles or color circles

⑵ causes:

① excessive amount of discharge agent (stannous chloride or carved white powder)

② the color paste is too thin or the hygroscopic agent is excessive

③ when printing by hand, the printing starts before the silk is dry

④ the humidity in the steamer is too high or the lining is too damp during steaming

⑶ prevention measures:

① the amount of discharge agent should be appropriate, and the effect of cleaning should not be blindly pursued. Otherwise, the strength of the fabric will be seriously affected; Or change the type of discharge agent. Use a variety with low hygroscopicity

② choose the original paste with good water holding property, and adjust the dosage of hygroscopic agent at any time according to season and climate changes

③ before steaming, the box should be preheated, the time of large exhaust should be extended, and the cold air in the box should be exhausted; The lining cloth used should be clean and dry; Strictly control the humidity and pressure in the box, turn off the bottom steam, and keep the pressure in the box ≥ 0.25MPa

④ adopt portal steamer steaming to reduce eye circles

2. Unclear carving color

⑴ form: the discharge pattern is mixed with ground color, so that the design color is unclear or not bright. Generally, those with deep ground color and large discharge block surface are more obvious

⑵ causes:

① insufficient amount of discharge agent and incomplete destruction of ground color

② the ground color dye is improperly selected, such as the dye is not easy to be reduced, it is easy to be colored by decomposition products and has high affinity for fibers, or the fixation process is adopted after the ground color is dyed

③ the pattern is long haired or the washing is not clean

④ uneven feeding during discharge printing

⑤ not steaming in time after printing or improper steaming conditions, such as insufficient steaming pressure, too short time, unstable temperature and humidity, etc

⑶ prevention measures:

① measure the dosage and pH value of discharge agent in advance, and use discharge pulp as it is prepared. If the dosage is insufficient, it should be supplemented in time

② dye the ground color with dyes that are easy to pull out and easy to wash the decomposition products, and the color will not be fixed after dyeing

③ carefully check and wash the version before using the patterned version. In case of serious hair, replace the new version in time

④ adjust the angle and pressure of the scraper to make the slurry feeding uniform

⑤ steam in time after printing, and control the steaming process conditions

3 color dots

⑴ form: there should be undesirable same color or different color dots on the cloth

⑵ causes:

① incomplete dye dissolution

② the original paste is too thin or sticky

③ the frame is not tight

④ when manually printing on the platen, the action is too fast or the force is too heavy when lifting the pattern, so that the color paste splashes out

⑤ falling of other dyes

⑶ prevention measures:

① when mixing, the dye should be fully dissolved and filtered into the original paste. For insoluble dyes, some cosolvent or dispersant can be added appropriately to help dissolve or disperse. Do not set the color paste for a long time after mixing to prevent the dye molecules from regrouping

② the viscosity of the original paste should be moderate and the mixing should be uniform

③ tighten properly when tightening

④ the pamphlet of sizing and printing is compiled by technical experts organized by Guangxi Institute of metrology. It should be isolated to prevent heterochromatic dyes from blowing off the cloth

⑤ when scraping manually, the starting action should be light and straight

4. Uneven ground color and uneven design color

⑴ form: there are dark and light spots on the ground or flower of the cloth

⑵ causes:

① uneven degumming, wax stains or unclear water

② poor color paste penetration

③ the ground color of discharge printing is improperly selected or the amount of discharge agent is too small

④ the table surface is uneven or rough, and the degree of softness and hardness is obviously different (mostly in manual table printing)

⑤ uneven scraping pressure or uneven blade edge of scraper

⑶ prevention measures:

① the green silk should be cooked, the degumming should be uniform, and the washing should be clean. When printing block patterns on crepe fabrics, they should be flattened and stretched before printing

② for fabrics with poor moisture absorption or in the case of poor color paste permeability, an appropriate amount of penetrant can be added to the color paste

③ when discharge printing, the ground color dye should be correctly selected according to the reduction ability of discharge agent; According to the depth of ground color and the size of pattern area, the suitable dosage of discharge agent is determined through proofing test

④ keep the table level, smooth and clean. Repair the worn parts in time

⑤ select the scraper blade according to the pattern. The blade should be straight, the left and right angles should be equal, and the reciprocating scraping pressure should be the same

5. Melting and water inlet tank

⑴ form: the color of the pattern seeps around, causing the outline of the pattern to be blurred. If the fabric is opened in a large area, it is called the water inlet tank

⑵ causes:

① the color paste is too thin and the water seeps, resulting in dye migration

② the original paste has poor water holding property. If polyester silk like fabric is printed with starch paste, it is very easy to produce biochemical products

③ too much moisture in grey cloth

④ the stencil was not wiped dry after washing

⑤ during steaming, the humidity in the steamer is too high or the lining is too wet or too wet before steaming

⑥ mechanical failure, the fabric enters the water tank with the guide belt after printing

⑦ at present, in the field of fatigue performance testing in quality inspection, scientific research, universities, construction, highways, railways, bridges, automobiles, machinery, nuclear power, water conservancy, ports, tunnels, coal and other industries, the fabric tension is not adjusted properly, and the fabric is brought into the water tank

⑶ prevention measures:

① different fabrics have different requirements for the viscosity of the color paste, and the color code should be scraped before printing. The color paste is too thick and difficult to print. If the color paste is too thin, it is easy to produce biochemical opening

② when preparing the color paste, choose the original paste with good water holding property. If the water holding capacity of the factory is poor, the mixed paste can be used instead, or the original paste variety can be changed. Avoid changing the original paste when it is put into production, which will affect normal production

③ generally, three dryness should be achieved in printing, that is, the printing guide belt, the printing fabric and the flower frame should be dry

④ if the fabric needs to be wet before steaming, it should be wet evenly by spray. During steaming, the lining cloth should be dry and the humidity in the box should be well controlled

⑤ if the machine fails, check the machine immediately and repair it in time

⑥ adjust the fabric tension to separate the printed fabric from the guide belt in time

⒍ paint falling off

⑴ form: the paint on the cloth surface falls off irregularly, making the pattern fuzzy and incomplete

⑵ causes:

① improper selection, deterioration or poor adhesion of adhesive

② the grey cloth surface is too smooth or greasy, which affects the normal adhesion of the color paste

③ during manual printing, the silk surface is too dry after printing, and the silk is uncoiled too hard to avoid dust falling into the equipment too fast

⑶ prevention methods:

① slurry mixing should be less and frequent, especially in summer, to prevent deterioration

② the pretreatment of printed fabrics should meet the standard. We should combine the characteristics of printed fabrics and choose adhesives reasonably. For fabrics with particularly smooth surfaces, adhesives with strong adhesion should be selected

③ for hot platen printing, it is best to uncover the silk by rolling

⒎ unclear multicolor coating

⑴ form: the multicolor pattern on the cloth coating is fuzzy and the level is unclear

⑵ causes:

① the viscosity of paint paste is not enough

② incorrect selection of multicolor coating

③ when printing, the spacing between the front and rear two sets of stencils is too close, and the front set of color paste is not dry, and the multicolor color paste is overprinted, resulting in paste

⑶ prevention methods:

① paint color paste should be prepared less and frequently, and the dosage of adhesive and thickener should be correctly determined

② adjust the prescription of multicolor paint paste to improve its coverage

③ enlarge the printing interval between the front and back two stencils as much as possible