reducion de problemas en estampado

PRINTOP® is a registered trademark of SOCIEDAD QUÍMICA ALEMANA S.A. Central: Av. Revolución 842 – Zona Industrial – Ventanilla / Callao Lima – Perú

Phone: +(51-1) 553-4141 Fax: +(51-1) 553-4361 www.printop.com / [email protected]

GUIDE FOR REDUCING PROBLEMS IN THE

TEXTILE PRINTING PROCESS



REDUCING PROBLEMS IN TEXTILE PRINTING

The object of this article is to serve as a small source of suggestions for users of inks and other products for textile printing. There are certain to be times when problems occur that affect total or partial production and are due to failures or omissions during the production process, that if they were observed in time, could have been corrected easily, thus saving the printer concern, time and money , later.

QUALITY CONTROL

1.1. The Sample: When a sample print out is made for a client, we must assure ourselves that it can pass all the tests required by the client. It is recommended that the rigor demanded by the client is exceeded.In addition, each printer has its own tests which must also be applied to the sample. The printer must know if the sample is to be submitted to an industrial process after being printed, generally speaking this would be washing or an industrial wearing process. If this were to be the case, the rigor of the tests on the sample must be maximum. 1.2. The Process: During the printing process, tests must be made to ensure that we are obtaining the quality desired according to our sample. During a high production of the same color and design, printings number 10, 50, 200, 500, 1000, 2000, 5000, 10000, 15000, 20000, 25000, etc. (from then on, every 5000 printed). must be rigorously tested. The demand and rigor of each test must be EXACTLY EQUAL to that of the sample. The tests made must be filed for later checking, should this be necessary.

1.2.1. Heat curing: Heat curing ovens do not keep an exactly linear temperature, slight fluctuations being inevitable. These fluctuations can be critical when dealing with printings having heavy ink deposits, particularly in ribbed type fabrics, 3D (“high density”) printings or dark fabrics. When there are very thick printings, the ideal would be to reduce the velocity of the oven conveyor belt to give the thick coats of ink the necessary curing time.

1.3 Tests: The quality control tests that must be normally carried out are the following; Visual appearance, elasticity, brightness, tacking, softness, dry crock fastness and wet crock fastness. In addition,Printop suggests color matching , bleeding and dye transfer tests. If the reader wants documentation regarding these tests, he may contact us for suitable guidance.

PRIOR INFORMATION: Bedire accepting any production, the printer must receive details in writing of all the quality control tests to which the production must be submitted. The test details must be very complete and include values, where possible. Likewise, the printer’s client must provide all information on the type of weave and fiber (of the fabric, the meshes, ribs, etc.), type and form of dyeing, colorants involved (or pigments), etc. For the post printing processes to which the production will be submitted, the printer’s client must provide the widest details of these processes (it will be preferable to have a flow diagram of the each process) for example, temperatures, times, quantity of garments per lot in process, chemical products involved, etc.

VARIOUS TECHNICAL CONSIDERATIONS:

3.1. Curing Defects: When a plastisol is not completely heat cured, it normally splits or cracks. The elasticity test usually reveals whether the plastisol is well cured or not. In the case of “jersey” type fabrics with normal and similar stretching, the plastisol ink, being well printed, and with the necessary thickness, MUST NOT SPLIT, even if treated to a maximum stretch. Many times, when high production is needed in a short time, a higher speed for the oven conveyor is resorted to which causes a deficiency in the curing which is NOT VISIBLE to the naked eye.



3.2. Bleeding and Efflorescence: This problem consists if the appearance of regular or irregular stains or streaks of color on the printing. When a fabric or garment has a previous pigmentation process (dyeing with pigments), the client must be assured that the pigment used for dyeing is compatible with the plastisol. In any case, the client must provide the printer with information on the type of pigment(s) in the dyeing process.

This is important information, since with it (and better still with a previous sample of the fabric) compatibility can be determined and problems of bleeding and efflorescence avoided. It should be noted that these problems can show up in a time of 6 to 24 hours after having been printed, for which reason, losses could be very large. The majority of existing pigments ARE NOT COMPATIBLE with plastisol.

This phenomenon is also met frequently when dyed fabrics of polyester fiber or mixtures of polyester/cotton are printed., since the colorants used for dyeing polyester have a very low sublimation temperature (particularly the reds, cherry and some blues and/or mixtures of these tones) which in the end, cause staining of the printed layers of plastisol.

This article does not constitute any guarantee whatsoever relative to Sociedad Química Alemana S.A. nor to its distributors. Its preparation is based on our good faith and experience. It is the choice of the user to apply or not the suggestions appearing in the article under its absolute responsibility and risk. Sociedad Química Alemana S.A. does not assume any responsibility whatsoever, for the use, following and/or results (direct or indirect damage, loss of profit, contractual and commercial implications, etc.) arising from the application of the guidelines described herein.

reducion de problemas en estampado

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