Textile Chemistry

PVC-Migration:

noreply@blogger.com (Adnan Chaudhry) — Wed, 21 Dec 2011 18:08:00 +0000

PVC-Migration:

PVC, Polyvinyl chloride test is carried out in textile, Specially pigment dyeing and printing). Purpose of this test to observe the behavior of pigment at high temperature. It is solely a pigment property and varying or changing binder, fixative and other auxiliaries will not alter the results of this test. Pigment during manufacturing are sometimes tinted with disperse dyes to obtain exact tone. Raw material of pigments are often mixed up and resultantly poor fastness to PVC. Earlier, It was believed that poor PVC is inherited property of pigment but today to the present knowledge, one reason of this poor PVC fastness can be addition of disperse dyes, which. It has been due to sublimation of disperse dyes which causes this issue.

PVC test is carried out at 80°C with continuous air flow,Perspirometer can be utilized for this task. Pressure of 12.5kps is applied which is again also the requirement of perspiration test ISO 105 EO4. Apparatus or assembly consists of two glass plates. One PVC film and secondly a oil which can plasticize at higher temperature. Fabric is placed on PVC sheet and than four to five drops of oil are poured onto the fabric. Glass/Plastic plate (Resistable to heat 80°C) is placed onto the fabric and whole setup is placed in perspirometer for 3 hours at 80°C.

White PVC Plastic sheet...

To verify the above discussion, we will carry out a test. In this test we will be using a black pigment.

We will be making up one printing glass by adding these elements and will be calling it normal recipe denoted by N in our figures.

Pigment (black)

Binder

urea

Ammonia

Thickener

And second printing paste glass will be consisting of these elements and we will be calling it extra ordinary and will be denoted by EO in our figures.

Pigment (black) + Disperse dyes (Black just a tint, Very little Amount)

Binder

urea

Ammonia

Thickener

We will print these glasses and results after printing are.

Normal Recipe ( N ).......Extra ordinary Recipe ( EO )

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Understanding Data color

noreply@blogger.com (Adnan Chaudhry) — Mon, 28 Nov 2011 13:50:00 +0000

Understanding Datacolor

Datacolor is an instrument which works by emitting a single or multiple wavelengths on to substrate (target) and then records the reflectance values. Afterwards uses these values to create a skeleton or graph which shows how substrate has behaved with varying wavelength. Typical wavelength used here is of visible region that is of 400nm to 700nm. For example let say we are trying to read values of a black fabric through data color. As, we know black color absorb every wavelength which fall on to it. That’s why it appears black,

Behavior of Black fabric

Same happens with data color graph and it shows zero or near to no reflectance value. We will be getting results reverse we try to repeat this experiment with white fabric and we will be having maximum reflectance value.

Behavior of White Fabric

Visible region of Electromagnetic waves covers from 400 to 700nm and colors vary on different wavelength as we move from 400 to 700nm we see Yellow toRed .

%Reflectance value for green color and graph will be like

Behavior of Green fabric

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Comparison of Hydrogen peroxide bleaching and conventional sodium chlorite bleaching

noreply@blogger.com (Adnan Chaudhry) — Thu, 29 Sep 2011 17:20:00 +0000

Hydrogen peroxide Bleaching.

Hydrogen peroxide is most widely used bleaching agent. Beside the good removal of the seeds, there peroxide bleach delivers a high degree of whiteness, the white effects are stable and do not tend to yellow during storage.

Results expected from hydrogen peroxide bleaching

Degree of whiteness: High degree of whiteness for white goods and pastel shades.

Seed removal : Complete removal of seeds coats.

*Criteria*	*Hydrogen peroxide*	*Sodium Chlorite*
Accelerated Continuous process	Yes	No
Applicability by all possible methods, e.g. cold bleach	Yes	No
Suitability for natural fiber	Yes	Yes
Efficient removal of husks	Yes	Limited
High water absorbing power	Yes	NO
Odor Irritation	No	YES
Corrosion problems(Vessel of resistant material required)	No	Yes
Suitability for combination processes (Boiling off/Bleaching)	Yes	No
One bath application with brighteners for cellulosic fiber	Yes	Limited
Deposits on fabrics and machines	Limited	No

On the whole, there are so many points in favor of hydrogen peroxide bleaching that it is easy to understand why it so widely used.

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Utilizing Bifunctional reactive dyes for reactive printing.

noreply@blogger.com (Adnan Chaudhry) — Thu, 08 Sep 2011 13:42:00 +0000

SUBJ:

Utilizing Bi functional reactive dyes for reactive printing.

Chemistry of dyes which are used in reactive printing is different from other classes. Among them one is MCT (Mono chlor Triazine), A dye having single chlorine attached to functional Triazine.

This Chemistry of dyes (MCT) provided better fastnesses, Specially washing fastness ISO 105 CO3, Dipping fastness.

A common practice is to use other family of reactive dyes in printing although this fulfills the task and advantages associated with this phenomena are
1) cheap/Economical dyes.
2) Bulk amount available
3)Nearly same shade depth and tone

But, disadvantages are poor fastnesses. Commonly in use dyes for reactive dyeing includes bi functional dyes including new generation high built dyes. These dyes have high fixation values and percentage of hydrolyze dye in dye bath is quite low but these dyes can not stand on with alkaline medium for longer period of time.

Stock paste used for printing include alginate, mild oxidizing agent, urea and above all quite huge quantity of soda ash (25g/Kg), which is recommended for fixation of reactive dyes in printing. As, already mentioned these dyes are not quite good with alkaline medium when left for longer period of time. So, when these dyes are mixed with stock paste and not printed soon or after immediate addition. These start to hydrolyze and lose up its strength and tone. Temperature work as catalyst here. Temperature effect inversely to the hydrolyzation. More the temperature more quickly dye is going to hydrolyze. As, major areas of Pakistan are hot and quite hardly hit in summer. So, for this experiment 50°C is chosen to check the hydrolyzation rate of bi functional and Purely MCT dyes.

For a clear Preview, Right click on image and open in new Tab or in new Window

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How reactive dye works?

noreply@blogger.com (Adnan Chaudhry) — Wed, 24 Aug 2011 14:26:00 +0000

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White discharge on 100% Polyester Knit Fabric dyed with disperse dyes in exhaust process.

noreply@blogger.com (Adnan Chaudhry) — Tue, 07 Jun 2011 18:45:00 +0000

Object:
White discharge on 100% Polyester Knit Fabric dyed with disperse dyes in exhaust process.

Chemicals:
Leveling agent, Swelling agent, Caustic solid Pellets, Special Thickener modified (to sustain high alkaline ph), Sodium Hydro sulfite.

Detail:
Discharging, disperse dyed fabric is more difficult as compared to reactive dyed cotton fabric and knit fabric adds more complexity. For discharging polyester common in use chemicals are Rangolit C and Tin chloride (Later one is strong reducing agent and expensive too). Results with these two are satisfactory when fabric is woven and just have undergone through padding and not fixed, in other words these reducing agents work well at pre fixation stage but if disperse dye is fixed its quite hard to remove or cut dye from selected area. In case of knit as dyeing is done in exhaust phase, at temperature 130°C so discharging reaches near to impossible. So, here what we have selected is, Two very cheap chemicals, Which will play their part in changing the chemistry of disperse dyes to obtain our result. These two legends are Caustic (NaOH) and Sodium Hydrosulfite (Na2SO4). Principle of discharge is simple and that is” no disperse dye can with stand high alkaline medium generated by 100% Caustic, Although we do listen some dyes are stable to alkaline medium but believe no dye have a chance to with stand such high alkaline medium.” So, basing on this principle we can utilize these chemicals, One can ask why not than choose only one chemicals between Sodium hydro sulfite and caustic? Answer to this question is very simple. Sodium hydrosulfite works well until its critical concentration reaches and above this it will not work efficiently, we can call this a saturation limit, in addition it has very pungent order. On the other hand concentration of caustic above 10% start to causing tear and weakens the fabrics too much. So our typical recipe will be as follow.

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Polyester (PES) Discharge/Disperse Discharge through Alkali (Soda Ash, Na2CO3)

noreply@blogger.com (Adnan Chaudhry) — Mon, 07 Mar 2011 17:48:00 +0000

SUBJ-20:

Polyester (PES) Discharge/Disperse Discharge through Alkali (Soda Ash, Na2CO3)

Chemicals:

Synthetic Thickener (Polysacchride), Soda Ash, Sodium Hydro sulfite and Caustic for Reduction Cleaning (although not necessary, it is done to have shin and glorious effect), Disperse Dyes

1. Stable to Alkali

2. Not Stable to Alkali.

Bit Discussion:

Polyester dyed or printed fabric can also be discharged but discharging requires more severe conditions like chemicals and parameters to obtain good results. Discharge of Polyester is more crucial and every dye cannot be discharged.

Normally there are two ways to Discharge a polyester fabric printed through Disperse dyes. First, utilization of simple alkali like soda ash which provides alkaline medium required to carry out discharge and other is done through utilization of Ragolit C and Tin Chloride.

Here in this post we are going to utilize former method in which we will be discharging though alkali soda ash. There are two kind of disperse dyes. One, Which are not stable to Alkaline medium at all and Second, Those disperse dyes which can bit stand with alkaline medium. So, this is basic principle which we are going to utilize in our both discharges, white and color Discharge.

Process:

Dyeing Recipe:

Padding Liquor{Continuous Process}

Disperse Dye (Not stable to Alkali) 30 g/Kg

Acetic Acid To Adjust Ph between 5-6

Water Balance

Total 1 Kg

Pad at pressure 2bar with pick up 70 to 80.

Dry at 110C° for 1Min.

After Dyeing, Not fixed Yet and remember, we need not to fix it here.

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Pigment Printing

noreply@blogger.com (Adnan Chaudhry) — Mon, 28 Feb 2011 18:23:00 +0000

SUBJ-19:

Pigment Printing

Pigment Printing:

For me design/Pattern is printing for others combination of thickener (Paste) and Screen (Design) is called printing. Dyeing can hold single color where as printing can handle 12 to 20 colors in single go. Printing can simply be classified according to Technique, Fiber type and Dye Class.

Note: On graph Bigger the pie {portion of circle} bigger the percentage of that part have. For example Rotary screen on first have more than 50% portion of the circle meaning internationally more than 50% printing is done through rotary printing.

As, Chart Describes major portion of textile printing is covered by Pigment Printing so it becomes an important topic to discuss.To print on different substrates different chemistry is required for example printing on natural cellulose is majorly done with reactive dyes. Polyester is printed with disperse dyes, Cotton is printed with sulfur dyes, but, Pigment printing can be applied to various type of fibers like Cotton, Polyester, Blend PC, Polyamide and many more. Isnt that great enough that one learns a technique of printing and now can apply on every type of substrate. This is really big advantage in the court of pigment printing that makes it more ecological, eco-friendly, efficient and safe.

Pigment Printed on 100% Cotton, Unmercerized

Pigment printing can be taken as wall painting, literally wall painting{Distemper}. If we look at the major constituents involved in wall paint are Binder, COLOR{Pigment}, Thickener, Drying Oil, Drying Agent, Fillers etc. Ok, Lets now see the composition of pigment printing paste its Binder, COLOR{Pigment}, Urea {for controlling formaldehyde}, Thickener, Ammonia{for adjustment of pH}. So, Closely looking the constituents will evaluate that around 65 to 80% components are same in pigment printing and Wall painting Distemper. In simple same constituents same chemistry that wholly relays on the working of Binder and of course we will love it to discuss with you.

Pigment Printed

Understanding Binder:

Nor Pigment printing neither Wall painting is possible without Binder. Binders plays key role in both former and later fields. Binder are mononers which on heating get converted into polymers. Yes I said by simple heating, no pressure , no steaming , no electricity.

Binders{Monomer}------Heat----------> Plasticizer/Plastic{Polymer}

Yeah, binders form plastic but, its too soft and transparent that its difficult to see it but we can feel its harshness on the fabric. That’s why pigment printed fabric have more harshness when compared to other printing techniques. Binder actually hold the pigment color and sandwich it between fabric surface and plastic coating and this coating help color to stick there and stand with high and severe conditions.

In addition to binder an other component is also added to the textile pigment printing paste and that is called fixer. Fixers are mostly formaldehyde based. Have you ever heard word UREA-FORMALDEHYDE, haana? Actually this is a plastic and used to make plastic plates and dishes with two component Urea {NH2}2CO and Formaldehyde {HCHO} as name suggests. So, Here in our paste formaldehyde work in same manner and form plastic which helps in strengthening of binder to hold on pigment

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Studying all possible Fixation Modes of Reactive Printing. Evaluating CMC and Strength Report through Data Color

noreply@blogger.com (Adnan Chaudhry) — Sun, 27 Feb 2011 11:27:00 +0000

SUBJ-3:

Studying all possible Fixation Modes of Reactive Printing. Evaluating CMC and Strength Report through Data Color

Chemicals:

Dye, Stock paste.

Purpose:

Purpose is to propose different fixation modes other than recommended (Steaming) with little or no compromise on yield and tone of shade.

Recipe:

Stock paste:

Mild. Oxidizing agent 10 g/Kg

Urea 100g/Kg

Sodium Bicarbonate 25 g/Kg

Alginate Thickener 25 g/Kg

Water Balance

Total 1 Kg

Dye Glass:

Dye 50 g/Kg

Stock paste Balance

Total 1 Kg

Options:

Options which are being tried are as follow.

Fixation through Curing/Heating only at strenter (Oven) without Air Flow Control.

Fixation through Curing/Heating only at strenter with Air Flow Control.

Fixation through Steaming by utilizing Saturated Steam.

In addition to these modes different other parameters like time was also varied to see the behavior of the dyes on varying fixation Modes.

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Jeans/Denim pents/trousers seem first resistance to Snake bites

noreply@blogger.com (Adnan Chaudhry) — Sat, 26 Feb 2011 10:53:00 +0000

Narrated and Coated "When I was a medical student, I served a summer externship in 1975 with the Indian Health Service at Fort Belknap in Harlem, Montana. On some hot summer evenings, I went fishing at a place the locals called "Snake Lake," which was loaded with cutthroat trout, and surrounded by rocky outcroppings that were home to scores of rattlesnakes. I was advised to stay away from the rocks, and to always wear long pants.

In the December, 2009 issue of the Annals of Emergency Medicine (Ann Emerg Med 2009;54:830-836), there appeared an article reporting a study by Shelton Herbert, PhD and William Hayes, PhD entitled "Denim Clothing Reduces Venom Expenditure by Rattlesnakes Striking Defensively at Model Human Limbs." The purpose of the study was to determine whether ordinary clothing (denim material from blue jeans) interferes with the kinematics of venom delivery, thereby reducing the amount of venom injected by a typical snake into a (model) human limb.

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Discharge is like ABC...

noreply@blogger.com (Adnan Chaudhry) — Sat, 26 Feb 2011 08:14:00 +0000

Self Explanatory Video

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Color Discharge on Reactive Printed/Dyed fabric through Sulfur Dyes.

noreply@blogger.com (Adnan Chaudhry) — Sat, 12 Feb 2011 15:33:00 +0000

SUBJ-19:

Color Discharge on Reactive Printed/Dyed fabric through Sulfur Dyes.

Chemicals:

Urea, Sodium Bicrarbonater, Sulfur Dyes, Reactive Dyes, Rangolit C (Sodium formaldehyde Sulfoxylate HOCH2SO2Na). Sodium perborate, Textile Washing off agent.

Discharge:

Discharge is not a new term for a textile Person. Discharge is classified into white and Color Discharge. Term Discharge may be mixed up or used instead of stripping which is not right as stripping is to lower the depth of shade (usual dyers term) where as during discharge screens are used to create patterns by removing partial or full color of the fabric (Textile Printers term).

Printing is now done on variety of fabrics consequently with variety of dyes. In this post we are just focusing on discharging cotton fabric printed/Dyed with Reactive dyes. Suitable discharging agent for reactive dyes or printed fabric is Rangolit C (Sodium formaldehyde Sulfoxylate HOCH2SO2Na). It is prepared by chemically reacting dilute solution of formaldehyde with Sodium Hydrosulfite. So, like Hydrosulfite it is also strong reducing agents. That why no dye can stand with Rangolit and get reduced consequently ending up by losing their colors. Therefore discharging reactive with reactive is not frequently heard process.

Black Ground Discharged with Yellow Sulfur Dye.

As, discussed Earlier discharge can be of two types White or color Discharge. White is done with rangolic C and later one is majorly carried out with Pigment and Binder system, Such binders are considered which are stable with rangolit C. so Rangolit C (Sodium formaldehyde Sulfoxylate HOCH2SO2Na) discharges ground dyed/Printed Fabric and resultantly pigment take over the white ground produced by rangolit C. The only drawback in this process is that pigment printed fabrics have very poor rubbing and washing fastnesses. So, One has to compromise at this end. So, why not to propose some other method rather than a typical pigment binder color discharge.

Purpose:

Purpose is to propose an other method else than pigment binder for color discharge on reactive Printed/Dyed Fabric.

Sulfur Dye Suitability:

Sulfur dyes are reduced before dyeing or Printing.Normally this is done with reducing agent like Sodium Hydrosulfite Na2S2O4. As, we have discussed earlier Rangolit C (Sodium formaldehyde Sulfoxylate HOCH2SO2Na) is a reducing agent which can replace Hydro sulfite but, Here need of Rangolit will be much greater as it has to perform two tasks one, Iit has to reduce the dye and secondly it has to discharge the ground color.

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

noreply@blogger.com (Adnan Chaudhry) — Fri, 28 Jan 2011 15:22:00 +0000

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

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Resist Printing

noreply@blogger.com (Adnan Chaudhry) — Fri, 14 Jan 2011 17:14:00 +0000

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.

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Industry News.

noreply@blogger.com (Adnan Chaudhry) — Wed, 12 Jan 2011 11:53:00 +0000

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).

noreply@blogger.com (Adnan Chaudhry) — Wed, 12 Jan 2011 11:27:00 +0000

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

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Sulfur Printing (Coating).

noreply@blogger.com (Adnan Chaudhry) — Sun, 02 Jan 2011 11:06:00 +0000

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.

Reduction of Dye
Printing
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.

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Pre Wash with Acetic acid can control back staining specially in the case of Turquoise Color.

noreply@blogger.com (Adnan Chaudhry) — Thu, 30 Dec 2010 12:47:00 +0000

SUBJ-14:

Pre Wash with Acetic acid can control back staining specially in the case of Turquoise Color.

Chemicals:

Acetic Acid (Conc), Sodium Alginate, Soap (Polyglycolether, Nonionic).

Process:

Purpose is to control back staining during washing in reactive printing. Some red and all turquoise bleed a lot during washing. Washing fastness like ISO 105 CO3 and 105 CO6/C2S also shows that turquoise are have very poor fastness, Any way in this post we are only concerning about the reacting after washing off of freshly printed fabric. We are not concerned with any kind of fastness like washing, Perspiration and Dipping etc.

Recipe:

Stock paste:

Mild. Oxidizing agent 10 g/Kg

Urea 100g/Kg

Sodium Bicarbonate 25g/Kg

Alginate Thickener 25g/Kg

Water Balance

Total 1 Kg

Dye Glass:

Dye 50g/Kg

Stock paste Balance

Total 1 Kg

Process:

Print and dry at 110-120°C for 1Min.

Cure at 200C for 1 Min

Prewash

With and Without Acetic Acid

With..................Without...............

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Pakistan asks India to keep up promise of cotton export

noreply@blogger.com (Adnan Chaudhry) — Tue, 28 Dec 2010 16:34:00 +0000

With Pakistan reeling from the after-effects of floods, its textile mill sector has appealed to India to honour the commitments for dispatching raw cotton, in letter and in spirit.

After floods devastated large tracts of farm land, cotton production in Pakistan was affected along with other major crops. In such a situation, Pakistani textile mills not only require the contracted amount of cotton from India, but a liberal gesture in the form of additional raw cotton as well.

Addressing a press conference here, All-Pakistan Textile Mills Association vice chairman Shahzad Ali Khan pointed out that India exported only one lakh bales out of the contracted quantity of 10 lakh bales. What the industry needed was not just the entire contracted amount, but an additional quantity. India had so far exported about 30 lakh bales of cotton to other countries and was in a position to assist the Pakistani textile industry.

Urging India to “help a neighbour,” Mr. Khan expressed the hope that the remaining quantity of nine lakh bales would be shipped at the earliest. Pakistan faces a severe supply crunch on the raw cotton front due to floods in parts of cotton growing areas in the country. Pakistan lost about 25 lakh bales of cotton and faces an overall deficit of 40 lakh bales.

The Pakistan Textile Mills Association, he said, had already submitted a request in this regard to the Indian High Commission in Islamabad. A similar plea has been lodged with the Pakistan High Commission with the hope that it would be followed up with the Indian industry and the government. Desperate for succour from India, the Pakistani textile industry has also taken up the issue with the cotton exporters in Mumbai.

Source:

INDIAN NEWSPAPER THE HINDU

Discharge Printing on direct dyed fabric with Potassium permanganate(KMnO4).

noreply@blogger.com (Adnan Chaudhry) — Mon, 27 Dec 2010 16:41:00 +0000

SUBJ-13:

Discharge Printing on direct dyed fabric with Potassium permanganate(KMnO4).

Chemicals:

Potassium permanganate (Oxidizing agent), Sodium bisulfite (Reducing agent), Acetic Acid (Conc), Special Thickener (inorganic compound based on silicate), Soap (Polyglycolether, Nonionic).

Process:

Purpose is to discharge all direct dyed substrate through Oxidation reaction of Potassium permanganate in acidic pH and than Reduction through Sodium Bisulfite again in acid pH. than finally soaping.

Recipe:

Stock paste:

Special Thickerner 35g/Kg

Potassium permanganate 40g/Kg

Acetic Acid 10g/Kg

Water Balance

Total 1 Kg

Processing Steps Involved:

¯ Print and Dry at 100-120C.

¯ Washing off in a reduction for fifteen minutes at 70C, bath containing

1. Sodium Bisulfite 10g/L

2. Acetic Acid 0.5g/L

Wash for 10Min at 70C with Soap (Polyglycolether, Nonionic).

¯ Rinse Warm and Cold.

Remarks by:

Direct dyes have been used for quite long time for dyeing cellulosic fabric. These dyed fabric can be easily discharged through Sodium formaldehyde sulfoxylate (commonly called Rangolit C) or this can also be done through Potassium permanganate, Results are quite fine. Whole process is in front of you.

Testing and recommending commercial chemicals for controlling back staining in reactive printing washing and wash down effects of Denim ( Enzyme Wash, Stone Wash, Moon Wash)..

noreply@blogger.com (Adnan Chaudhry) — Fri, 24 Dec 2010 17:25:00 +0000

SUBJ-12:

Testing and recommending commercial chemicals for controlling back staining in reactive printing washing and wash down effects of Denim ( Enzyme Wash, Stone Wash, Moon Wash)..

Chemicals:

Dye( Tuquoise was taken for experiment as it is famous for a lot of back staining), Stock paste (Containing Urea, Bicarbonate, Mild oxidizing agent ), Hydrogen per oxide 35%, Soda ash, Routing soap for reactive washing(generally acrylic acids).

Purpose:

Back staining is quite a famous issue among printers as it stains white area and minimizes contrast effect and eventually compromising the added value. This is not only the issure for reactive printers but also for Denim industry, Who are busy in dyeing warp yarn of denim and leaving white weft and weaving style ending up with eye catching effect of jean. Now days, Different washes are very famous for carrying out different effects like Stone Wash, Enzyme wash and Moon Wash. When these washes are done dye is released from the warp yarn into liquor (containing some enzyme, acetic acid for maintaining appropriate Ph) these dyes bounce back towards fabric and stick to weft yarn so, again less contrast between warp and weft. New tint of blue from weft also fade down the actual Denim concept. So, what can be added to over washing recipe to control this issue.

With out H2O2... With H2O2...

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Sulfuric Acid ...King of Chemicals

noreply@blogger.com (Adnan Chaudhry) — Mon, 20 Dec 2010 15:27:00 +0000

Laboratory hazards

The corrosive properties of sulfuric acid are accentuated by its highly exothermic reaction with water. Burns from sulfuric acid are potentially more serious than those of comparable strong acids (e.g. hydrochloric acid), as there is additional tissue damage due to dehydration and particularly secondary thermal damage due to the heat liberated by the reaction with water.

The danger is greater with more concentrated preparations of sulfuric acid, but even the normal laboratory "dilute" grade (approximately 1 M, 10%) will char paper by dehydration if left in contact for a sufficient time. Therefore, solutions equal to or stronger than 1.5 M are labeled "CORROSIVE", while solutions greater than 0.5 M but less than 1.5 M are labeled "IRRITANT". Fuming sulfuric acid (oleum) is not recommended for use in schools as it is quite hazardous.

The standard first aid treatment for acid spills on the skin is, as for other corrosive agents, irrigation with large quantities of water. Washing is continued for at least ten to fifteen minutes to cool the tissue surrounding the acid burn and to prevent secondary damage. Contaminated clothing is removed immediately and the underlying skin washed thoroughly.

Preparation of the diluted acid can also be dangerous due to the heat released in the dilution process. The concentrated acid is always added to water and not the other way round, to take advantage of the relatively high heat capacity of water. Addition of water to concentrated sulfuric acid leads to the dispersal of a sulfuric acid aerosol or worse, an explosion. Preparation of solutions greater than 6 M (35%) in concentration is most dangerous, as the heat produced may be sufficient to boil the diluted acid: efficient mechanical stirring and external cooling (such as an ice bath) are essential.

On a laboratory scale, sulfuric acid can be diluted by pouring concentrated acid onto crushed ice made from de-ionized water. The ice melts in an endothermic process while dissolving the acid. The amount of heat needed to melt the ice in this process is greater than the amount of heat evolved by dissolving the acid so the solution remains cold. After all the ice has melted, further dilution can take place using water.

Source:

Wikipedia.org

The Textile Industry in Canada: Focus on Technical and Other Value Added Textiles

noreply@blogger.com (Adnan Chaudhry) — Fri, 17 Dec 2010 12:20:00 +0000

e Canadian textile industry has lost much of its competitiveness since the global elimination of quotas at the end of 2004, particularly in mass markets. Between 2005 and 2009 total factory sales by textile mills and textile product mills fell by 44% while sales by the clothing manufacturing industry dropped by 50%.

The textile industry has faced a number of challenges, including: competition from developing countries; offshore manufacturing by its traditional main customer, the clothing industry; availability, retention and training of the workforce; the strength of the Canadian dollar; trade regulation; capital availability; and access to specialised markets.

By 2006 it was apparent that the industry needed to diversify into specialised materials such as technical usage textiles (TUTs) and other value added textiles (OVATs). By targeting TUTs and OVATs the industry would be better able to meet, and stimulate, customer demand for products which met special requirements and offered heightened performance.

To ensure widespread adoption of this strategy, it was proposed that the strengths of the entire value chain be focused on TUTs or OVATs. This was to be achieved through: the utilisation of scientific and technical resources; the implementation of dynamic research and development cooperation platforms; innovation; commercialisation; and business networking.

The aim of this initiative is to help the industry to compete in the international market place and develop a critical mass. Consequently, its image will improve in the eyes of the public, the business community and the financial community, and the industry will be taken more seriously when major public and private clients are structuring their projects.

The initiative has already achieved some success. Between March 2007 and June 2009 the number of companies involved in technical and other value-added textiles rose from 241 to about 400, and in mid-2010 it was estimated that this figure had been more or less maintained.

Source:
http://www.just-style.com/market-research/the-textile-industry-in-canada-focus-on-technical-and-other-value-added-textiles_id98227.aspx?lk=ud79

Burn out printing on Blend PC (Polyester/Cotton ).

noreply@blogger.com (Adnan Chaudhry) — Thu, 16 Dec 2010 17:32:00 +0000

SUBJ-11:

Burn out printing on Blend PC (Polyester/Cotton ).

Chemicals:

Synthetic Thickener, Sodium Bisulfate, Penetrating Agent, Glycerin and Water.

Purpose:

Burnout is a beautiful effect, Which is carried out on blend fabric and specially for those blends which have high percentage of cotton and are reserved dyed (mean polyester portion is either dyed or printed), when cotton burns down dyed polyester gives full shade and vacant spaces. One can literally see across this type of effect.

One can take simple white fabric, blend of course. Dye or print it with disperse dye in acidic medium than apply burn out recipe afterwards go for reduction cleaning which is required for polyester. This cleaning will also wash down burned cotton.

Cotton can be chemically burnt out at 200C in presence of Sodium bisulfate (other chemicals were also tested in order to substitute sodium bi sulfate , which is discussed in later portion)

As a big house Masood textile on its website expresses.

Preview this picture on large scale

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Denim Discharge or Jeam Discharge

noreply@blogger.com (Adnan Chaudhry) — Thu, 16 Dec 2010 17:24:00 +0000

SUBJ-10:

Indigo Discharge, Vat Discharge, Denim Discharge or Jeam Discharge all in one.

Chemicals:

Potassium permanganate (Oxidizing agent), Sodium bisulfite (Reducing agent), Acetic Acid (Conc), Special Thickener, Soap (Polyglycolether, Nonionic).

Process:

Purpose is to discharge Blue or Black color Denim through Oxidation reaction of Potassium permanganate in acidic pH and than Reduction through Sodium Bisulfite again in acid pH. Finally soaping.

Recipe:

Stock paste:

Special Thickerner 35g/Kg

Potassium permanganate 40g/Kg

Acetic Acid 10g/Kg

Water Balance

Total 1 Kg

Processing Steps Involved:

¯ Print and Dry at 100-120C.

¯ Washing off in a reduction for fifteen minutes at 70C, bath containing

1. Sodium Bisulfite 10g/L

2. Acetic Acid 0.5g/L

Wash for 10Min at 70C with Soap (Polyglycolether, Nonionic).

¯ Rinse Warm and Cold.

Remarks:

This will clearly give you good discharge result. I will try to upload photo effects of these discharges. I also tried some other temperatures for drying which was 150 and 180C but, results were not too good (mean no big change). One can try other oxidizing agent and reducing agent like sodium pryrosulfite (Sodium meta bisulfite), Sodium Hydro sulfite.

Please Note Thickeners (Including both natural, Synthetic) are not compatible with potassium per manganate and acetic acid. They form jelly and heat is evolved during stirring. So, special thickeners are need for this kind of process. That’s why I used word “Special Thickener”. Still need to look for the chemistry of this special Thickener. If you are familiar with the chemistry of Special thickener. Comments are welcomed.

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