Studying effect of Viscosity on Shade Depth (Strength), CMC (Change of Shade) and Staining on White Ground.

SUBJ-18:

Studying effect of Viscosity on Shade Depth (Strength), CMC (Change of Shade) and Staining on White Ground.

Chemicals:

Dye, Stock paste with varying Viscosity. Viscosity can be obtained with high concentration of Thickener. For example Viscosity chosen for this experiment was 50,000 and 15,000 for Brookfield Viscometer spindle 6 and RPM 10.

Alginate Thickener at 40g/Kg approx gives Viscosity 15,000 at 6/10.

Alginate Thickener at 80g/Kg approx gives Viscosity 50,000 at 6/10.

Note: These concentrations are for general idea. You can test at your end to adjust viscosities.

Purpose:

Purpose is to studying effect of Viscosity on Shade Depth (Strength), CMC (Change of Shade) and Staining on White Ground while using same Mercerized Fabric and controlling all external parameters which can interfere with the result like (Time & Temperature during Drying, Steaming and washing.

Back preview of low and high viscous stock paste.

Recipe:

Stock paste:

Mild. Oxidizing agent             10  g/Kg

Urea                                        100g/Kg

Sodium Bicarbonate               25g/Kg

Alginate Thickener               Xg/Kg

Water                                      Balance

Total                                       1 Kg

Xg/Kg can be

Alginate Thickener at 40g/Kg approx gives Viscosity 15,000 at 6/10.

Alginate Thickener at 80g/Kg approx gives Viscosity 50,000 at 6/10

Resist Printing

SUBJ-17:

Resist Printing

Chemicals:

Dye (1. MCT Range Dye for ground print, 2. VS Range Dye for Over print), Urea, Sodium Bicarbonate, Sodium Sulfite, Alginate Thickener.

Purpose:

Resist printing is a special effect like Discharge printing. As name suggests resist mean TO STOP. Background of fabric in this technique is colored with a dye having MCT (Mono chloro Triazine) Chemistry. Dyes having this chemistry is more stable to reducing agents like Sodium sulfite which is main player in resist printing. So, Ground printing paste has dye, thickener, mild oxidizing agent, Sodium sulfite. While Over print(Full Bloch) dyes are chosen from VS (Vinyl Sulfone) Range. These dyes are unstable to reducing agents like Sodium sulfite

Consequntly a Ground printed portion (usually design/pattern)have sulfite and will eat up all Over color (Full Bloch) on that region. So, over print will only survive those regions which don’t have ground printed. Through this mechanism we can achieve versatile designs and patterns.

Difference Between Discharge and Resist Printing:

Sometime People may confuse Discharge and Resist Printing. Both are two different methods and have versatile useage in textile industry. Results are amazing and adimreable with very low economy (No extra screens, No high class machinery, No special chemicals).

Discharge:

Ground color is eaten up/Destroyed chemically with Sodium formaldehyde sulfoxylate normally called Rangolit C.

Resist:

Over color is eaten up/Destroyed chemically through Soium Sulfite.

Industry News.

4 banks join hands to boost textile industry

The four international as well as local banks have provided trade finance coverage of 110 million euros to Ibrahim Fibers Limited to import modern German machinery for production of polyester staple fiber and polyester chips. Due to this trade finance the Ibrahim Fiber’s polyester production capacity will further be increased by 650 tons per day to 1,250 tons to make it more than double.

The MCB Bank, Asian Development Bank, International Finance Corporation and Citibank have announced that they have completed a trade transaction that will help boost the textile industry in Pakistan, a sector that accounts for over 60 percent of the country’s industrial activity, said a press release, posted on the website of the ADB.

It is to be noted that last year, ADB’s Trade Finance Program supported over $600 million of cross-border trade in Pakistan. Over the past six months, IFC has provided Pakistani banks with $328 million in trade finance guarantees, a $125 million increase in guarantees compared to the same period last year. The trade financing helps Pakistan increase cross-border trade, and benefits many important business sectors.

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Using Commercially available chemicals for the fixation of sulfur dyes in Sulfur Printing (Coating).

SUBJ-16:
Using Commercially available chemicals for the fixation of sulfur dyes in Sulfur Printing (Coating).

Chemicals:

Sodium Bicarbonate, Sodium perborate, Zinc Oxide, Resist Salt, Borax, Sodium Alginate, Soap (Polyglycolether, Nonionic).

Purpose:

Chemical Industries are offering different products for better fixation (oxidation) of sulfur dyed/Printed or coated fabric to ensure good wash fastness and to meet the requirement of buyer. Many Standards included in ISO used chemicals which are true test of color. So, meeting the need is a goal here.

Oxidation is the last step involve in printing of Sulfur Dyes. Oxidation phenomena actually brought back the dye to its original structure Big complex Molecular structure which is actually responsible for the good washing fastness of sulfur Dyes. Different Oxidation method which can be applied are

Oxidation through Air (atmospheric oxygen)

Oxidation through Chemicals

Acetic Acid

Hydrogen Peroxide

Commercially available Oxidizing agent like One of the famous in market Clariant product Diresul Oxidant BRI.

Sodium Bicarbonate

Sodium boromate
Sodium perborate
Resist Salt

Sulfur Printing (Coating).

SUBJ-15:

Sulfur Printing (Coating).

Chemicals:

Sodium Sulfide or SSodium Hydrosulfite (Na2s2o4), Acetic Acid (Conc), hydrogen peroxide, Sodium Bicarbonate, Sodium Borate, Levling Agent(If Possible), Dispersing Agent (If Possible)Sodium Alginate, Soap (Polyglycolether, Nonionic).

Purpose:

Major use of Sulfur dyes as for as printing is concerned finds in coating application of Denim and heavy GSM twill fabrics. After coating with sulfur different washing outs are carried out like

Stonewash

 Enzyme Wash

 Hypochlorite Washings.

There are three classes of sulfur dyes, which are available commercially,
1.Conventional water insoluble dyes which have no substantively to cellulosic’s.
2.Solubilised sulfur dyes , which are water soluble and non substantive to cellulosic’s.
3.Pre-reduced sulfur dyes, in the stabilized leuco compound form , which are substantive to cellulosic’s.

These Washings gives very beautiful effects to denim fabric all because of Sulfur Dyes.

Sulfur Dyes:

Sulfur dyes are cheap with good washing fastness. Procedure is also quite simple. Stages Involved are.

1. Reduction of Dye
2. Printing
3. Oxidation of Dye

Reduction

This step is generally carried out in the presence of some reducing agent. Common reducing agent being utilized are Sodium Sulfite and King of reducing agents (HYDROS F) Sodium Hydrosulfite (Na2s2o4). Recipe of Sulfur Printing describes 3% amount of Reducing agent regarding to the concentration of dye is sufficient. Sulfur Molecules are complex and larger in Size So, insoluble in water and also have no substantivity towards the fabric. They are reduced to smaller size in the presence of some suitable reducer this makes the dyes to get solubilize and dye shows substantivity towards fabric too.

Some other parameter which are generally not being practiced while printing with sulfur dyes or coating are involved in reduction of dyes during dyeing are as follow

For Dyeing

Here it is worthy to mention that. During dyeing of sulfur. In addition to reducing agent. Caustic (NaoH) is also added. Ph is normally above 10. Temperature of the reduction bath is kept to 80C.