BASIC INK FORMULA FOR SCREEN PRINTING

CÔNG THỨC CĂN BẢN CỦA MỰC IN KHUNG VẢI

PLASTISOL BASE + PIGMENT CONCENTRATE = INK

           INK MODIFICATIONS

    We can modify or adjust the ink properties to fit our purposes by adding an additive to it.

Before start using any additive, we should read or try to remember the supplier’s guidelines about the percentage,

 the opacity effect, the proper curing temperature and the pre-test.

Among of many additives, the followings are frequently used : reducer , thickener, dulling paste and catalyst

( % by weight )

Ink  +  reducer  ( 3-10 % )                          Ink becomes thinner , running and less opaque

                                                                      no hanging in the screen.

Ink  +  thickener  ( 1-3 % )                         Ink becomes thick , less flow.

Ink  +  dulling paste  ( 10 % )                    Ink loses the gloss , becomes dull , no more shiny.

Ink  +  catalyst ( 10 % )                              Ink adheres firmly to synthetic fabrics

Frequently used additives

WHAT IS THE PIGMENT CONCENTRATE ?

The pigment concentrate is a colored man made stuff or a colored natural mineral ground into very

fine powder with a plasticizer.

The fine powder only disperses in the plasticizer but does not dissolve in it.

So the pigment concentrate is completely different with the dyestuffs dissolved in a solution used for

dyeing textiles.

Evaluation of a  pigment concentrate

 - Good dispersion in plasticizer and base.

 - Color strength must be acceptable.

 - Good stability to heat.

 - Resistant to fading.                                    
 - No reaction with additives.




 WHAT IS THE PLASTISOL BASE ?

       The plastisol base is a resin polyvinyl chloride (PVC) blended with a plasticizer of high boiling temperature.

The resin is a white powder of 0.5 –2 microns. The plasticizer is a clear and oily by-product from petroleum industry. When these two components are mixed thoroughly, we get a sticky and greasy stuff called plastisol base.

Under the proper temperature, the resin softens and swells then fuses to the plasticizer or the resin absorbs completely the plasticizer .We say it is cured. The proper curing temperature is about 300 -350 *F in 3 minutes. It depends on producers.

 Plastisol pretest evaluation.

If the plastisol ink is set to dry under a no correct curing temperature, it will not resist to washing, rubbing and in later there will be a problem of pigment migration. So before running the production, we must remember to set the proper curing temperature for the dryer, and then perform tests as follows:

·          Rub a white piece of fabric on the dry ink. If the white fabric has no stain, the curing temperature is correct.

·          Use fingernail to scratch the ink film. If there are no flakes or crumbles. We get the right curing temperature.

     COMMERCIAL NAMES OF  PLASTISOL BASES 

Plastisol bases are labeled with different commercial names depending on manufacturers’ purposes.

There are also many more plastisol bases that can be cured at lower temperature.

            Ngoài thị trường mực in được quảng cáo và bán theo hai cách.

* Mực đã pha trộn sẵn. Có nhiều màu khác nhau. Chọn mua những màu theo ý  thích đem về in.

* Dùng những chất liệu có bán sẵn, tự pha trộn màu theo ý muốn.

 * Mỗi màu mực ,căn bản có những thành phần cấu tạo như sau.

- Chất keo ( plastisol ̣base+plasticizer)

- Chât́ làm mềm ( reducer )

- Chất màu ( pigments concentrate ).