Dyestuff Selection - manufacturers' suggestion - an important phase in processing

Selecting the proper trichromatic combination of 3 dyes that have almost similar substantivity, exhaustion and fixation properties is very important for getting the best reproducible shade matching.

Nuchem Dyestuffs P Ltd., is making the following suggestions for its customers.


General guidelines:

LIGHT SHADES	MEDIUM SHADES	DARK SHADES
For Good Light fastness and levelness: Cotfix Yellow CA Cotfix Red CA Cotfix Blue CA Cotfix Amber CA Cotfix Yellow FN2R Cotfix Red FN2BL Cotfix Blue FNR Cotfix Blue FNG For all round optimum fastness: Cotfix Yellow RR Cotfix Red RR Cotfix Blue RR Cotfix Yellow 5GL Cotfix Yellow F3R Cotfix Red F3B Cotfix Blue BB Cotfix Blue BRN	For Good Light fastness and levelness: Cotfix Yellow FN2R Cotfix Red FN2BL Cotfix Blue FNR Cotfix Blue FNG For all round optimum fastness: Cotfix Yellow RGB Cotfix Red RGB Cotfix Blue RGB Cotfix Navy RGB Cotfix Caramine RGB Cotfix Yellow NL-2R Cotfix Red NL-5B Cotfix Blue NL-BR Cotfix Navy NL-R	Dark Shades: Cotfix Yellow RGB Cotfix Red RGB Cotfix Blue RGB Cotfix Navy RGB Cotfix Caramine RGB Cotfix Ultra Yellow RGB Cotfix Ultra Red RGB Cotfix Yellow D Cotfix Red D Cotfix Navy DB Cotfix Orange D Cotfix Deep Red DB Cotfix Dark Blue DB

This guideline is only a general thumb rule and one should not come to a conclusion that this is the ultimate criteria. The dyer, based on his final requirement or end use of the dyed material, has to select proper group of dyestuff.

CA, FN and NL series would meet the wide range of fastness requirements of the industry.

RGB and Ultra RGB series are most suitable for medium and dark shades, where one would expect no metamerism.

W series are exceptionally suitable for wide range of dark shades, where economy is of prime importance. With series generally one can dye uniforms like dark browns, Olives and Dull blues.

D series posses exceptionally all sound fastness parameters and are economical too for dyeing dark and very dark shades.

HF series produce exceptionally bright shades and possess very high tinctorial values, most suitable for dyeing and printing, exhaust and CPB applications.

This classification is further elaborated as below:

1.     Lemon Yellow

2.     Yellow, Golden Yellow

3.     Orange, Scarlet

4.     Red

5.     Wine, Maroon

6.     Violet

7.     Blue, Royal

8.     Turquoise, Bright Green

9.     Navy Blue, Black

10.  Beige, Light Blue, Grey

11.  Brown

12.  Dark Green, Olive

 

Lemon Yellow

Cotfix Yellow 5GL

Cotfix Yellow ME4GL

Cotfix Yellow F4G

Yellow, Golden Yellow

Cotfix Golden Yellow F3R

Cotfix Red F3B

Cotfix Blue BB

Cotfix Yellow GR

Cotfix Orange 2R

Cotfix Orange 3R

Cotfix Orange ME2RL 

Orange, Scarlet

Cotfix Orange 3R

Cotfix Orange ME2RL

Cotfix  Oange 2R

Cotfix Yellow F4GL

Cotfix Yellow GR

Cotfix G.Yellow RNL 150%

Cotfix Red F3B

Cotfix Navy Blue BFN

 Red

Cotfix Yellow GR

Cotfix G.Yellow RNL

Cotfix Orange 3R

Cotfix Orange 2R

Cotfix Orange D

Cotfix Deep Red DB

Cotfix Red D

Cotfix Scarlet HF-3G

Cotfix Orange HF-2GL

Cotfix Blue BB

Wine, Maroon

Cotfix Yellow GR

Cotfix Yellow RNL-150%

Cotfix Deep Red DB

Cotfix Caramine RGB

Cotfix Ultra Red RGB

Cotfix Navy Blue RGB

Cotfix Navy Blue BFN

Cotfix Blue R SPL.

 Violet

Cotfix Golden Yellow F3R

Cotfix Orange ME2RL

Cotfix Red ME6BL

Cotfix Red ME4BL

Cotfix Violet 5R

Cotfix Navy Blue R SPL

Cotfix Navy Blue BFN

Cotfix Blue BRN

Blue, Royal

Cotfix Blue BRN

Cotfix Navy Blue BFN

Cotfix Golden Yellow R 150

Cotfix T/Q Blue H2GP, G

Cotfix Blue R spl

Cotfix Blue BB

Turquoise, Bright Green

Cotfix Yellow F4G

Cotfix Golden Yellow F3R

Cotfix Yellow ME4GL

Cotfix Blue R SPL

Cotfix T/Q Blue H2GP

Cotfix Blue BB

Navy, Black

Cotfix Golden Yellow R 150

Cotfix Red ME6BL

Cotfix Red RGB

Cotfix Red ME4BL

Cotfix Navy Blue R spl

Cotfix Navy Blue BFN

Cotfix Black ECO

Cotfix Black WNN

Cotfix Supra Black G

Cotfix Black B 133%

Beige, Light Blue, Grey

Cotfix Blue BRN

Cotfix Yellow RR

Cotfix Red RR

Cotfix Blue RR

Cotfix Yellow CA

Cotfix Red CA

Cotfix Blue CA

Cotfix Red HF-G

Brown

Cotfix Golden Yellow WR

Cotfix Red WB

Cotfix Navy Blue WB

Cotfix Orange W3R

Cotfix Dark Blue WR

Cotfix Yellow RGB

Cotfix Red RGB

Cotfix Blue RGB

Cotfix Navy RGB

Cotfix Caramine RGB

Cotfix Ultra Yellow RGB

Cotfix Ultra Red RGB

Cotfix Yellow D

Cotfix Red D

Cotfix Navy DB

Cotfix Orange D

Cotfix Deep Red DB

Cotfix Dark Blue DB

 Dark Green, Olive

Cotfix yellow RGB

Cotfix Red RGB

Cotfix Blue RGB

Cotfix Navy RGB

Cotfix Yellow D 

Cotfix Red D

Cotfix Navy DB

Cotfix Orange D

Cotfix Deep Red DB

Cotfix Dark Blue DB

Discharge Printing/Dyeing - Dischargeable dyes - How to select dyestuffs for dischrge print?

Discharge Printing

Pre-Conditions for Fabrics to Be Printed

There are 3 basic conditions a fabric must possess to be considered for today’s Unit Print or T-Shirt Print market.  These are:

  1. Uniformity in Print Bottom.

  2. Dis-chargeable to Sulfite Based Discharging agents.

  3. Dyed Bottom Compatibility with Print Vehicle.

The first point includes such considerations as uniform washing and scouring, the use of "print friendly" add-on (softeners, wetting agents, resins, etc.), and uniform absorbency.

The second point describes the pre-dying step and the fact that dye selection for shade matching must include the behavior of the dyed fabric after finishing.  The print vehicle at use in the majority of the Digital Thermal Printers contains solvents and emulsifiers which will have an affinity of the dyes on the fabric.   The Dyeing process for reactive dyes includes a washing step to remove the excess dye. However,  subsequent  finishing  with  acid products  can  cause  certain  reactive  dyes  to  release  some  of  the  fixed  dye  and  this would then "Bloom" into the print due to the heat of curing and fixing of the print. The Reactive dyes are not affected by the acid treatment and would not be subject to breakdown in this manner.

The other dye classes for cotton such as direct, sulfur, vats and pigment are more prone to exhibit a tendency to bloom than the reactive dyes. In the case of Polyester or Polyester/Cotton blended fabrics the polyester dye must be dyed without carrier and given a good reductive scour or some disperse dye remains on the cotton and all disperse dyes are soluble  to some extent  in  the solvent of  the print vehicle.

The phenomenon of dye transport in the fiber is a reversible physical/chemical reaction.  This means that even with a good dying procedure, dye will return to the surface of the fiber and be accessible to the print vehicle after any heat processing (drying, etc.).  The  fact  that  the  dying  process  is  not  a  guarantee  of  a  print-friendly mandates  the selection of dyes based on  solubility  in  the print  vehicle.   Some of  this  information  is known  but  testing  of  existing  shades  should  be  done.   The dyeing for testing should always be made on the Polyester/Cotton fabric in the absence of the cotton dye but the fabric should be subjected to the Cotton dye procedure.

The third point is dis-chargeability of the Cotton dye.  The most popular and used dyes for the cotton fabrics are the reactive dyes.    Not all reactive dyes are dis-chargeable completely and there must be a selection of dyes used to match shades that are to be marketed as dis-chargeable. As a group, the fiber reactive dyes offer the widest selection for this criterion.

COTFIX DYES:  DISCHARGE and RESIST

The terminology used to describe these two processes is sometimes confusing to the Textile Industry.    The  first  order  of  business, then,  has  to  be  a  definition  and description of these two processes.

R E S I S T

 Resist  is  the  term  used  to  describe  the  Prevention  of    the  Dyeing  Process brought  about  by  the  application  to  the  fabric  of  a Mechanical, Physical  or Chemical Substance  to prevent Dye Access  to  the Fabric.   This done  in such a manner  that a Pattern is realized in the Dyed Goods.

D I S C H A R G E

 Discharge is the term used to describe the displacement of a dyed shade by a Chemical Process in such a manner that a pattern is imparted to the dyed fabric.

·         The fabric is Dyed First.

·         The Discharge Agent is applied to the fabric normally by Printing.

·         The fabric is processed to get the discharge.

·         Then the fabric is washed to remove the Byproducts of Discharge.

·         If color is added to the Discharge Agent, this is the Illuminating or Discharge Color.

·         If No color is added to the Discharge Agent, the result is a White Discharge.

The most common Discharge Agents are chemicals based on Sufoxylate Formaldehyde Chemistry.

DISCHARGE AGENTS

    The most common Discharge Agents are chemicals based on

·         Sufoxylate Formaldehyde Chemistry.

·         Sodium Sulfoxylate Formaldehyde   *  Vat Discharge

·         Zinc Sulfoxylate Formaldehyde    *  Pigment & Acid

·         Sodium Hydro Sulfite

·         Potassium Sulfoxylate Formaldehyde

·         Thiourea Dioxide Compounds

    * Hypo Chlorites are also used for specific articles

Cleavage products that must be removed by washing to get to the final shade are left on the fabric.    These may  be  amides  that  are  easily  saponified  and  removed  by washing.  They may or may not be colored themselves. 

COTFIX DYES FOR DISCHARGE PRINT: GROUND SHADE PRODUCTION

The  following  COTFIX  Dyes  are  dis-chargeable  by  either  the  alkaline  or  the  acid Sulfoxylate Formaldehyde Procedures.

The maximum concentration of dye used to make a shade match affects the discharge obtainable. The maximum recommended amounts of each Cotfix Dye are included.

This list  should be used  for all dyeing  that  requires  that  the  shade be dischargeable. 

The most trouble free dyes for this procedure are marked by  Good & Fair. 

Cotfix Dye	Discharge	Max.Conc	REMARKS
Br. Yellow 4GL	Yes	50 gpl	Good
Br.Yellow GL	Yes	50 gpl	Fair
Golden Yellow RNL	Yes	50 gpl	Good
Br.Orange 3R	Yes	50 gpl	Good
Br.Red F3B	Yes	30 gpl	Fair
Br.Red 5B	Yes	50 gpl	Good
Br.Violet 5R	Yes	30 gpl	Fair
Blue BB	Yes	30 gpl	Fair
T.Blue G, H2GP, H5G	Yes	15 gpl	Fair
Navy RGB	Yes	60 gpl	Good
Black B	Yes	80 gpl	Good
Black RGB	Yes	80 gpl	Good

 

 

All Turquoise Dyes are very difficult to discharge and should not be recommended for this procedure.  The exception is in cases where Turquoise is needed for Green shades. Shade discharge is dependent on the dyestuff used and NOT the Technique used to make the dyeing.

Cotfix Dyes:

Selection for Dischargeable Shade Production

Black  

      Cotfix Black B

      Cotfix Black NF 

      Cotfix Deep Black RGB

      Cotfix Navy R-GB                               

      Cotfix Golden Yellow RNL 

      Cotfix Brill. Red F3B                          

              

Navy

      Cotfix Black B               

      Cotfix Navy Blue R-GB        

      Cotfix Brill. Red F3B        

      Cotfix Orange 3R   

     

Dark Green

      Cotfix Orange 3R

      Cotfix Navy RGB

      Cotfix Brill. Blue BB

Blue  

      Cotfix Brill. Blue BB

      Cotfix Navy RGB

Royal  

      Cotfix Brill. Blue BB   

      Cotfix Brill. Red F3B        

      Cotfix Brill. Violet 5R 

                                                        

Turquoise

      Cotfix Turquoise G-A Maximum 1%: 10 g/l

      Cotfix Brill. Blue BB 

      Cotfix Navy RGB         

                                                        

Bright Green

      Cotfix Brill. Yellow 4GL 

      Cotfix Brill. Blue BB     

                                                         

Teal   

      Cotfix Brill. Yellow 4GL 

      Cotfix Brill. Blue BB    

      Cotfix Navy RGB        

       

Bright Red 

      Cotfix Brill. Red F3B        

      Cotfix Golden Yellow RNL

Red

     Cotfix Brill. Red F3B

Wine    

      Cotfix Brill. Violet 5R 

      Cotfix Brill. Blue BB 

      Cotfix Brill. Red F3B

Maroon

      Cotfix Brill. Violet 5R 

      Cotfix Brill. Orange 3R

      Cotfix Brill. Red F3B

Violet

      Cotfix Brill. Violet 5R 

      Cotfix Brill. Red F3B

      Cotfix Brill. Blue BB New

Scarlet

      Cotfix Brill. Red F3B                           

      Cotfix Brill. Yellow GL                        

       

                                                                  

Orange

      Cotfix Brill. Orange 3R                    

                                                                           

Golden Yellow

  Cotfix Golden Yellow RNL                                                        

                                                                                 

                                                                           

Lemon Yellow

  Cotfix Brill. Yellow 4GL                    

Note that the bright royal shades and the shades requiring the use of a   turquoise dye are difficult to match with the available dyes.

The use, even very sparingly, of both the Cotfix Turquoise G and the Cotfix Brilliant Blue R Special is not recommended if a consistently dis-chargeable bottom is desired.  It is customary for these shades to be matched either for discharge but slightly dull or for optimum brightness but not dis-chargeable.

Any shade can be matched using the list of dischargeable dyes and a reasonable result will be obtained.   The listing by shade groups insures the most reliable results from a performance view point.

This listing and grouping is far from a complete dictionary for dyeing and discharge but is our experience.    The  use  of  dischargeable  direct  dyes  would  be  similar  in  shade grouping but  the  resultant problems with  the dye diffusion  into  the solvent  in  the print vehicle would be greatly increased.

 

Cotfix Bifuntional Dyestuffs - for better exhaustion - most suitable dyes for knits.

Cotfix Bi-functional Dyes


The poor exhaustion and fixation properties of Vinylsulphone dyes that lead to lot of dyestuff wastage have given birth to the bi-functional dyes with medium exhaustion and better fixation properties.

Bifunctional dyes have filled a big vacuum of various hues of bright shades, which were not possible with vinyl sulphone type. The dyes were conventional Dichlorotriazine type, with the end condensation of ß-sulphato ethyl sulphone to have different type of reactive group in a single molecule. Being a dual reactive, the primary mode of fixation is from vinyl sulphone group and the dyeing temperature is same as vinyl-sulphone, which enables good, inter compatibility in between the two classes.

Methods of dyeing:

These bifunctional dyes are most suitable for exhaust dyeing and Pad Batch and continuous. Can be freely mixed in combinations with Vinyl Sulphone dyes.

Cotfix High Exhaust (HE) dyes - most suitable for garment dyeing!

Cotfix HE Dyes



Cotfix HE dyes are basically bis monochlorotriazine reactive dyes with low reactivity and high substantivity. These dyes are characterized by high but slow exhaustion and high fixation values. Washing off of dyed goods is easier due to higher fixation.

Due to the high fixation (85% and more) pollution problems are also minimized since the drained liquor contains minimal of unfixed dyes.


Characteristics of Cotfix HE dyes:

• Better reproducibility and hence batch to batch variation is minimized.


• High tinctorial value due to excellent build up properties


• Eco friendly due to higher fixation values.


• Better fastness properties.


• Wide range of application since it is suitable for all types of cellulosic materials like yarn, fiber, piece dyeing and garments.

Cotfix HE dyes are most suitable for garment dyeing, because of their high exhaustion and fixation properties at higher temperature (80°C) that facilitate uniform and level dyeing of stitched garments on all its parts like collar, scuffs and stitched yarn. Moreover because these dyes posses outstanding fastness characters when compared to other class of reactive dyes.


These dyes are most suitable for exhaust dyeing and in particular in that machinery where you can easily achieve and maintain the 80°C on the fabric.

Cotfix Hot Brands - Printing Dyes

Our cyanuric chloride based, Cotfix 'H' brand dyes forms various chemical linkage with hydroxyl groups of cellulose. These dyes are low substantive and high fixation dyes most suitable for dyeing and printing of cotton, viscose, cuprammonium rayon and natural silk. The dyeing temperature is 80°C.

METHOD OF DYEING: By Exhaust Dyeing:

Take well pre-scoured fabric and ensure that the pH of the fabric is 7, if require adjust pH by adding Acetic Acid. Take soft water for dyeing, if the water is hard, add sequestering agent to achieve best result.

Set the dye bath at 50ºC and add pre-dissolve dye in two portion and run for 10 min.

Add 5 gms./lit. Common salt for deep shade (2.5 gms./lit. for pale shade) and run for 10 min. start raising temperature to 80ºC - 85ºC in 30 min.

During raising temperature, 20 gms./lit. Common salt (10 gms./lit. for pale shade) after first 10 min. and add 25 gms./lit. Common salt (8 - 10 gms./lit. for pale shade) after another 10 min. and continue dye for 15 min. after reaching the temperature to 80ºC - 85ºC.

Add Alkali slowly in 15 min. and continue dyeing for further 45 - 75 min.

SALT AND ALKALI REQUIREMENTS FOR REACTIVE HOT DYES

COTFIX – H BRAND DYES IN PRINTING

In conventional one-step printing with reactive dyes, urea is used to increase solubility of the dyestuffs and to improve dyestuff migration from the printing paste to the textile fiber.

Minimization or even substitution of urea is possible in the one-step method by controlled addition of moisture.

Another option is the two-step printing method, involving the following steps:

• Padding of the printing paste

• Intermediate drying

• Padding with alkaline solution of fixating agents (especially water-glass)

• Fixation by means of overheated steam

• Washing steps (to remove thickeners and improve fastness properties).

The process is carried out without urea.

A typical recipe for the printing paste is given below:

Thickening stock solution:

Fixation is carried out by means of overheated steam (90 °C to 125 °C).