Fluorescent Pigment Dyeing

 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.

Phenolic Yellowing

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.

Silver Based Anti-Microbial Finish

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.

Steam boilers for textile:

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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Polyester dyeing with Carrier.

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.

Sulfur Dyeing -The way we do

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

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

Comparison of Hydrogen peroxide bleaching and conventional sodium chlorite bleaching

 

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.

Utilizing Bifunctional reactive dyes for reactive printing.

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.

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