Textile Chemistry

Fluorescent Pigment Dyeing

noreply@blogger.com (Adnan Chaudhry) — Mon, 29 Feb 2016 06:05:00 +0000

These days garment dyeing has been very common and very attractive to entrepreneurs. The major supporting bars are low investment, Variety of color and wash down effect, which can be achieved through same machinery with change of Dyes/Chemicals and processes. There is no limit to what can be achieved with this techniques.

Normally bleached twill/Knit with and without Lycra is procured/purchased and stitched in house to make garments. Woven twill for bottom wear and Knits for making T-Shirts and Hoodies.

These articles are then loaded to machines. Two kinds of machinery which is very famous here in this part of World is either Barrel Machine or Front Loading Machine.

Front loading machines have become very popular. As these are more controllable and can be programed to start/stop, In take chemicals, Dose/Inject and KMNO4 can be sprayed to garments. Sometime called Batik Effect. These are of course expensive compared to barrel machines. Major brand is Tonello Machinery.

Whereas with Barrel machines manual temperature and chemicals dosages are controlled. Chinese barrel machine suppliers have embedded automatic system in these machines also. With these atomization these can also control Temperature and PH and can perform several other important tasks.

Most of the textile dyer avoid pigment dyeing as according to them it would be difficult to wash off remains of binder on the machine but those days are gone. With today technology and available polymers it’s not a issue at all. We have done some working with different chemicals to show you the quality of levelness and shade which can be achieved with new performance dyes and chemicals.

Today in pigment dyeing, top of the list is Fluorescent pigment dyeing. One can achieve excellent levelness and great results.

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Phenolic Yellowing

noreply@blogger.com (Adnan Chaudhry) — Fri, 19 Feb 2016 18:04:00 +0000

Yellowing as name called on very pale to full white fabric (Knit/Woven). Recently, had chance to visit a towel facility who is facing yellow streaks on towels.When full white OBA treated towels were tested for core ph. it was fount that ph is above 8.5 and present of Nitrogen dioxide in air has triggered the reaction.The wet storage for long period further catalyzed the yellowing.

A good definition of phenolic yellowing is expressed as "Yellowing is caused due to the presence of phenolic compounds on the textile material, reacting with the oxides of nitrogen in an alkaline medium. "

Oxides of nitrogen are generated in warehouses/households from direct heating systems or from automobile emissions in the urban environment. Neither the oxides of nitrogen nor the phenolic compounds by themselves cause yellowing, but when united, form the yellowing products.

BHT (Butyl Hydroxy Toulene) is added in polyethylene bags as anti oxidant to increase life of packaging bags and avoid air oxidation/Aging. It is good as for packaging material but, when this BHT reacts with textile material it caused yellowing. So, textile materials are often advised to not be placed in poly bags which have anti oxidents like BHT.This chemistry of BHT is low in cost and highly effective. Due to its low vapor pressure it is volatile and can be transferred to textile goods easily.

Polyamide (Nylon) is more prone to yellowing than cotton. This is due to the cationic amino groups present which react with anti oxidants.

Archroma product UMIDOL APY reacts with these cationic amino groups and block them to react with Anti oxidant and hence chances of yellowing minimizes.

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Silver Based Anti-Microbial Finish

noreply@blogger.com (Adnan Chaudhry) — Sun, 03 Feb 2013 08:48:00 +0000

Anti-Microbial Finish

Undergarments/Socks possess huge potential for this special finish. Buying houses and marketers like Mark & Spencer have done projects in past like “Undercover Agents” anti-microbial treatment on Underwear and “Fresh Feet” athletics socks which remains Fresh and Bacteria free for longer period.. Huge potential for this finish is still unexposed and will be shown up as awareness and Know how about working and advantages increases.

Microorganisms are life-forms of microscopic size (ca. 10-8 to 10-6 m), such as bacteria, fungi.Bacteria especially lead to body odor due to bacterial degradation of perspiration infection and illness

Microorganisms require certain conditions to exist, such as food, temperature, moisture and large surface areas. Hence, textiles worn, such as underwear, socks and are ideal for microorganisms.

Human Sweat

Sweat contains mainly water. It also contains minerals, lactate, and urea. Mineral composition varies with the individual; An indication of the minerals content is sodium (0.9 gram/liter), potassium (0.2 g/l), calcium (0.015 g/l), magnesium (0.0013 g/l). Source: www. wikipedia.org

Chemically saying Human perspiration/Sweat should not be smelly

The smell

Sweat by itself does not have much of an odor. Most of the smell is caused by bacteria which live on the skin and in clothing. These bacteria use the sweat for growing themselves. On average bacteria can double their numbers after every 10Minutes. Damped environment provides favorable medium for microorganisms growth.

We can find two kinds of anti-microbial finsh available in market. Silver and Non Silver Based Anti-Microbial.

Silver Based Anti-Microbial Finish

From old days silver has been successfully used as a Sterilizing agent. In the past silver coins were placed in vessels to preserve milk. Today the inside of refrigerators is made of silver-containing coatings to avoid buildup of bacteria resultantly fresh food for longer period.

In the food sector silver is used as an additive, e.g. for sweet coatings or decorating chocolates.

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Steam boilers for textile:

noreply@blogger.com (Adnan Chaudhry) — Wed, 23 Jan 2013 14:56:00 +0000

Steam boilers for textile:

Textile industry is suffering from energy crisis specially Gas, Low pressure and high demand among residence in winter causes complete breakdown. So, it’s high requirement to shift on alternate energy resources e.g. Coal. Country is very rich with its coal reserves and it can serve for quite long. In this post we will discuss possible energy alternates for textile industry, Economical aspect (Costing), Merits and demerits involved. Major focus is on costing to evaluate efficiency of different energy resources.

Industry utilizes different kind of boilers with varying pressure and of different capacities as per unit requirement.

Coal is being burnt down to provide heat Energy for boiler

Case Study:

Let’s assume a boiler working at pressure 5Bar and producing steam of Two Tons per hour. Efficiency of this boiler is approx. 80%.

What would be cost of producing 2Tons of steam per hour on Natural Gas, Coal and Furnace Oil?

Our solution to this scenario is a simple formula which says:

Efficiency(n) = Output Quantityof Steam(Qs) X Energy in Steam(hf)

Input Qt of Fuel (Qf) X Gross Cal. Val. (GCV) X Sp. Gravity of fuel

Omitting Specific Gravity of fuels to simplify and Shifting variables of formula from here to there and vice versa. So, that Final shape becomes.

Qf = Qs X hf

GCV X n

So, Here what these are

Qf = Quantity of fuel needed to produce 2Tons steam per hour at 5 Bar

Qs = Qunatity of steam. This is fixed value 2000Kg per hour

Hf = Enthalpy of evaporation which is Fix Value taken from Steam table,2757KJ/Kg of Steam.(Means One Kilogram of steam has this much energy at Pressure 5 Bar)

GCV = Gross caloric value, Different for each combustible material.

N = Efficiency of Boiler, Fixed quantity taken as 80%, we will put 0.8 in formula.

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Contact Us

noreply@blogger.com (Adnan Chaudhry) — Sun, 16 Dec 2012 13:19:00 +0000

For your precious and valuable feedback, Conatct Us page has been uploaded. You can ask anything related to posts. We will try our best to reply & revert back to you.

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Polyester dyeing with Carrier.

noreply@blogger.com (Adnan Chaudhry) — Tue, 16 Oct 2012 16:58:00 +0000

Textile Carrier.

A carrier is an organic chemical that has affinity to polyester and swells it. Chemicals such as Biphenyl, Orthophenylphenol, Benzyl benzoate, Benzyl benzoate and Butyl Phathalamide have been used as disperse dyes carriers. The use of Carrier at 100°C increases the amount of dye absorbed and decrease staining on other fibers. Carrier normally have unpleasant odour that require the dyebath to be enclosed and they may also be toxic.

Above swatches are Disperse dyed at 100°C, Exhaust

1. Dyed without carrier

2. Dyed with Carrier of Company X.

3. Dyed with carrier of Company Y.

What Carriers do?

Carrier helps in further penetration and resultantly better washing, rubbing and sublimation than with same dyeing depth without carrier at elevated temperature. Dyeing at high temperature without carrier is more economical than dyeing with carriers.

Experiment

Let’s do a test to confirm that Carriers can enhance fastness. We will dye two fabrics with same dye same concentration at elevated temperature of 130°C but, one with and other without carrier than we will do RC(Reduction Cleaning) and finally will apply test Sublimation test ISO 105 PO1 210°C.

Right one Without Carrier and left with carrier.

One can observe obvious improvement in sublimation fastness due to addition of career.

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Sulfur Dyeing -The way we do

noreply@blogger.com (Adnan Chaudhry) — Thu, 13 Sep 2012 18:54:00 +0000

Sulfur Dyeing -The way we do

Chemistry of sulfur dyes according to many books is still mystery and still could not get exact picture of nature of binding and activity but, with practical work we know many interesting things about sulfur dyes. Basic application of sulfur dyes is very simple “FIRST YOU REDUCE AND LATER YOU OXIDIZE”. Reduction is necessary to make these dyes soluble and to reduce we have two routes either to go with inorganic based reducing agents like sodium hydrosulfite or we can also reduce with organic reducer which are more environment friendly like glucose in presence of strong alkaline medium. Complete reduction of dyes can be determined through redox potentio meter a reading of -700 to -750 shows good reduction. It may need PH of above 10 to achieve that high reduced potential. After complete reduction this bath contain reduced dyes could be utilized for dyeing cellulose either in exhaust or continuous on pader. A typical reduction ready to dye recipe could be.

Recipe:

Sequester = 2g/L

Caustic(Solid = 5 to 7g/L

*Reducing agent = 3 to 15g/L

**Sulfur dyes (Liq = 80 to 200g/L

Penetrating agent = 2g/L

*(3 for inorganic based strong reducing agent like sodium hydrosulfite and 15 for organic based reducer.

** (Depends upon shade depth, preferably use pre-reduced liquid dyes.

Process:

Pad with 65 to 70% pick up.,

Dry at 120 to 130°C for 2 to 3 Min.

“FIRST YOU REDUCE AND LATER YOU OXIDIZE”. So, let’s oxidize now. Do you know oxidation of sulfur dyes can also be done by Hydrogen peroxide? Doesn’t it seem to be interesting as hydrogen peroxide is famous for its bleaching effect but we also know its oxidizing agent and that’s what we here required? Alternate to hydrogen peroxide we can also utilize commercially available oxidizing agents with acetic acid to oxidize.

What actually oxidation does is to cause insolubility of dyes. This insolubility of dyes helps in two ways. Firstly, by insoluble dyes got stuck into cellulose and secondly these dyes have now no affinity toward water and during washing it does not move away from fabric toward water hence showing average to good washing fastness.

Problems/Troubleshooting:

Sulfur dyeing is never been easy. It’s been of devils thing. There are many issues involved in sulfur dyeing and king of them is oxidation when we do not need of it. Oxidation of dyes in open container exposed to air. Oxidation of prepared liquors even pre mature oxidation of padded or exhaust dyed fabric resultantly variation in shades. To counter this in exhaust mode we utilize Tonello air tight packed machines. On pader we do it immediately after liquor prepared and never let it to stay and expose to air for longer.

An other problem is of tailing on padder. These dyes have high substantivity and it varies from color to color. Let’s study a scenario to make it easy to understand. Suppose we have a shade in which we are going to utilize two sulfur based dyes first one is black and second is orange. Black has more substantibity towards fabric than orange so what does it goanna do. So, when we started padding fabric as black dye was more substantive it rushed more quickly toward fabric rather than orange and resultantly after some time padder contains more orange than black and eventually changing shde tone.

With single component element strength keeps on losing up as dyeing progresses.

Solution could be to utilize apporx same substantive dyes.

Use not more than two dyes to make shade.

Pad with low liquor volume.

Go with high speed.

And speed is what counts after all…..

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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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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.