What Is The Chemical Cloth Finishing Process For Textiles & Why It Is Needed?Chemical finishing entails the use of chemicals to modify some property of the fiber so as to change the function, performance or aesthetic properties of the cloth or garment. The scope of chemical cloth finishing process is almost unlimited, but this chapter is mainly concerned with the achievement of dimensional stability in woolen and cellulosic knitted goods, wet and dry cross linking reactions, conferment or water and flame repellency and with the modification of the handle of synthetic fiber produce by softeners and stiffeners, etc. A limited number of specialty textile finishes, such as anti-static, are also considered.

Procesess of Textile Cloth Printingby Textile Engineer · 0 comments

There are enormous processes to textile cloth printing. But in textile industry, it is a crucial thing to go ahead with textile cloth printing by choosing a correct printing method. There are several methods of textile cloth printing. These are-

1. Direct Printing

2. Printing by Azoic or Napthol base.

3. Printing by Vat dyes.

4. Printing by rapid fast color.

5. Textile cloth printing by rapidjon color.

6. Textile printing by oxidation color.

7. Cloth printing by thelogen color.

8. Printing by Polyamide nylon fabric.

9. Textile printing of acrylic clothes.

10. Printing by reactive color.

Printing with Pigment Dye | Pigment Printing Concept

by Textile Engineer · 3 comments

Basics of Pigment Printing:

Due to the complexity of the printing with several so called dyes the printer are inclining to the pigment printing. Now a day, the percentage of using the pigment printing are increasing day by day because of the abundance of organic pigments and the binders that are used during printing textiles. There is always having a risk with using general dyestuffs as printing in case of the finishing treatment like fixing steam and washing that must have to be implemented.

Dyes are selected for printing by following the ability of the dyes that they are reproducible or not in case of different variations or the fabric and color condition. Researchers found from a survey that, the Azoic dyes is used in textile printing industry about 3%, disperse dyes are used about 10%, Vat dyes are used about 9%, Reactive Dyes are used about 25%. And the extent of the using of pigments in printing is about 50%.

Uses of Pigment Printing:

Pigment printing has wide range of uses. The garments of the women which are made by cotton, polyester or viscose blends are printed by pigments if the medium color depths are needed. Decorative curtain, towels are printed by pigments. Pigment printing also used in bed linen, aprons, children’s garments, night wear dresses, various cottons and cellulose materials.

Some advantages of pigment printing:

1. The great advantages of pigment printing are, if any mistakes are found during printing process, it can be easily detected.2. The process of pigment printing is very fast and economical as sampling can be done quickly and don’t need the washing.3. If the pigment print paste are created by proper process by selecting materials than it will have exclusive light fastness and other basic fastness properties also.4. Pigment print is very reliable and needs less labors and equipments.

Some disadvantages of pigment printing:

1. Handling properties of the pigment printing is rough because of having excessive cross linking agents.2. Creates problem on the roller printing because of the bulky products and more engraved rollers.3. It is not possible to apply it directly on the fabric. Binder must be used to apply the pigment dye on the fabric. Thus, a coat is created on the surface of the fabric.4. During second time printing it has very low effect that is not desirable.

Features & Types of Pigment That Are Used by Textile Dyers

Pigments are similar to dye and mostly used in textile printing industries. Pigments have some great feature. Here I will mention these features and different types of pigments that are usually used in industry.Features of Pigments

1. Pigment has excellent light and weathering fastness.

2. By pigment the high curing is possible and has a good backing stability.3. It has high tintorial strength.4. Pigment yield bright and sharp0 color in printing.5. It provides excellent solvent resistance6. Pigments are easily dispersible.7. By using pigment; you can create consistent and uniqueness of shed.

Various Types of Pigment Dyes

1. Organic Pigments.2. In-organic Pigments.3. Azo-Pigments.4. Mettalic Pigments.5. Fluorescent Pigments.

On the basis of color, pigments are divided into two classes:

1. White Pigments.2. Colored Pigments.

What Is The Difference Between Dyes & Pigment?by Textile Engineer · 1 comment

I have seen a lot of Textile Engineers who are confused about the difference between dyes and pigments.

There are some basic differences between dyes and pigments from which you can be clear about the main features of these two.

Dyes are the material which can be applied on the fabric or yarn surface and shows color visible to they human eyes in the presence of light. Dyes can be found in liquid and solid forms. And on the other hand; Pigments are colored, white or fluorescent particulate organic and inorganic solids which usually are insoluble in water and physically, chemically unaffected by the substrates in which they are incorporated. Generally Dyes are soluble in Water. Pigments are 100% insoluble. Dyes are composed of Organic substances. Pigments are organic and inorganic materials. Dyes materials have three components; these are – Chromophor, Auxhochromo and Chromogen. Other end; pigments have two parts like Chromophore and chromogen. Dyes are selectively applied. Pigments can be applied to all fibers. The fastness properties of Dyes are good. Fastness property of Pigment is average. Dyes are widely used in Dyeing. Pigments are widely used in Printing.

Dyes are comparatively expensive. Pigments are comparatively cheap.

A long period is needed for dyestuff to be applied. Pigments need lower time to be applied.

Dyes have direct affinity to fibers. Pigment has no affinity to fibers. Pigments need other modifier to increase affinity to textile fibers.

These are the basic difference between dyes and pigments.

Pretreatment For Fabrics Before Dyeing & PrintingTo produce colored Fabric whether dyed or printed needs pre-treatment of those fabrics of those fabrics before dyeing and printing . The pretreatment operations involved for cotton fabric are described systematically below:

Singeing:

It is the process of burning out projecting hairy fibres from surface of the grey fabric by assigns the fabric through a gas flame. Both sides of the fabric are burnt out by the flame. It helps in subsequent chemical process of the fabric. After dyeing or printing of singed fabric, brightness and luster of color and fabric becomes better.

Desizing:

it is the pr4ocess of removing starch materials present in the gray fabric. Generally enzyme is used to degrade and remove the starch present in the grey fabric. If those size materials are not removed from the grey fabrics, then the subsequent chemical treatments on the fabric will be irregular, which will cause he defective dyeing and printing.

Scouring:

It is the process of removing natural impurities present in the cotton fibre. The natural impurities are pectin’s, pectos, ash, wax, mineral compounds, etc. if those impurities present in the cotton fibres are not removed, then it will be difficult to dye or print the fabric uniformly. Normally caustic soda ash is used as main reagent fro scouring of cotton fabric.

Bleaching:

It is the process of removing natural coloring matters present in the cotton fibre. For his purpose, hydrogen peroxide, bleaching powder or other bleaching agents are used. Hydrogen peroxide is the best and most commonly used bleaching agent. If this bleaching treatment is not carried out before dyeing or printing hen the color yield and shade matching may be a great problem.

Mercerization:

It is a special chemical pre-treatment on cotton fabric t improves the properties and performance of cotton fabric. The cotton fabric is treated under tension in the 20% caustic soda solution which is called mercerization many properties of cotton fabric is improved, some of them are mentioned below:

1.Increases fabric strength2.Increases absorbency power3.Increases fabric luster4.Increases fabric softness and handle property5.Reduces dye consumption6.Reduces chemical consumption in dyeing.

What Precaution Should Be Taken Before Dyeing a Garments?

Garments made from cotton grey fabric are dyed in garments with the garments dyeing machine. Before garments dyeing some precautions are needed to avoid dyeing problems that may occur during garments dyeing.The precautions of Garment Dyeing are discussed below:

1. Garments design should be made from engineering point of view.2. if garmet is made after desizing, scouring and bleaching of grey fabrics and then dyed in garments form, then the possibility of problems will be reduced,3. if possible, garments should be made from the grey fabrics of the same lot and same source.4. the seams should not be too tight or too loose especiallu in the areas containing elastic like waistband, cuff aetc which may create irregular dye penetration resulting irregular dyeing.5. the garmens which are produced from woven and knitted fabrics combindly, he knit fabric should be pre-shrunked, otherwise seam pucker may develop after garments dyeing.6. if the garment fabric is of mixed fibres, during gaments dyeing, dye selection should be done carefully, having equqal dye pick up to avoid irregular dyeing.7. poor quality metals should bot be used as accessories in the garments, which may vbe damaged duing dyeing by the action of salt and alkali. If any metal component is used in the garments should be made from nickel or its alloy.8. sewing thread used for making the garment should be of same fibre like the garment fabric, other43wise colour difference may occur between garments fabric and sewing thread.9. button used in the garments should be selected carefully. Buttons made from casin, cellulose, mylon etc. may be damaged during garments dyeing but polyester button is safe in this project.10. if elastic is used in the garments and the elastic is made from natural rubber of polyurethance fibre like lycrea amy create problelm during garments dyeing. To avoid such problem dye should be selected made of copper free. During bleaching, polyurethance fibres may be damaged by the chlorine. Polyester type elastomeric fibre is safe in peroxide bleaching.11. interlining is used in most garments. Only those interlinings should be sed in the garments to be dyed only recommended for garments dyeing, otherwise the performance of interlining may

be destroyed.12. the garments made from compactly woven cotton fabric should be dyed with hot brand reactive dyes, otherwise problem of irregular dye penetration may occur.13. for some specific colour, if specific dyes are dused then the dyeing cost will be lower. For example, navy blue and black colour could be procuce in the garments by using sulpher dyes at lower cost.14. presence of mineral impurities in the cotton fibres may vary which may impede the stability of peroxide liquor during bleaching with bydrogen peroxide. Even insoluble compounds may form during hydrogen peroxide bleaching. Those insoluble compounds may redposit on chemicals are available to avoid such problem.15. Crease marks may develop in the cotton garments during dyeing. To avoid such problem, special chemicals like “Imacol Brand” may be used.

Advantages & Disadvantages of Hand Screen Printing In Textile IndustryAdvantages of Hand Screen Printing:

There are several advantages of Hand Screen Printing that we must have to know. These are -

Less Investment Cost: As there is no machine required in hand screen printing and it is possible to print in a shorter space; the total investment in hand screen printing is comparatively lower than other screen printing system.

No Risk: No heavier instrument or machine tools are used in hand screen printing. So, there is no risk.

Multi-color Design Can be Printed: In hand screen printing procedures various colors can be used effectively.

Less Floor Space Is Required: As no heavier and bigger machines and related tools are used, the hand screen printing requires lower space to install.

Suitable For Small Scale Production: If you want to install a screen printing factory for you local business, you can choose the hand screen printing at the initial stage as it requires lower cost or investment.

Disadvantages of Hand Screen Printing:

Besides the advantages of hand screen printing; we have to know about the disadvantages of Hand Screen Printing too. Because it is needed for developing the process or solving any problems occurred during installation.

Slow Production Rate: As no machine is used and all of the process are done by manually; the production rate becomes lower than other printing process.

Small Scale Production: If you want to own a big screen printing factory or if you have some bigger plan in future; the hand screen printing is not for you. Due to some reason this kind of printing process provides you lesser production rate.

Labor Intensive Process: A labor has to work manually and all of the process of the hand screen printing is done by the hands. So it needs more time to produce a product.

Fastness Properties Are Average: As all of the process is done manually, the fastness properties of the printed fabric is not well.

Difficult to maintain even penetration and print paste.

Skilled Man-Power is required.

Why Garments Dyeing is more benefited?The important advantages or benefits of Garments Dyeing are summarized below:–

1. Comparatively lower cost of production for any item of any color and shade.2. Comparatively less time is required to produce and supply garments.3. No possibility of shade variation within the garments.4. Small lots of different items could be produced at lower cost within less time.5. Old garments could be redyed hence, becomes like new garments.6. Desizing , scouring, bleaching, dyeing and finishing could be done n he same machine.7. Comparatively lower capital investment cost to set up a garments dyeing project.8. In some cases, lower liquor ration in garments dyeing requires lower water, steam and chemical consumption, hence lower garments dyeing cost.9. During fabric cutting approximately 15% fabric is cut out as wastage, if this 15% fabric is cut out as rey fabric rather than coloured fabric. Then the wastage cost will be saved.

You can consider these steps to be evaluate before making any decision of dyeing. Hope, garment dyeing will be rock to you.

Detergent for Textile Pretreatment| Detergent effects/impacts on textileby Textile Engineer · 0 comments

Detergent:

Detergents are surface active compounds which get orient at the interface (between water and air) and reduce interfacial tension. It removes dirt from the surface of the textile material by emulsification and suspends the dirt in cleaning liquid. Detergent effects on textile drastically.

Classification of Detergent:

Detergents impacts on textile are classified mainly in two- 1. Ionic 2. Non-ionic.

Ionic detergent also divided into three – 1. Anionic 2. Cationic 3. Amphoteric.

1. Anionic Detergent: After being ionized, anion is the dominating ion. For example – Soap. The reaction is-

C17H35CooNa C17H35Coo- + Na+

C17H35Coo- this portion is very large and dominating ion.

2. Cationic Detergent: After being ionized, cation is the dominating ion. Example- Catyl Pyridinium Chloride.

3. Amphoteric Detergent: Soluble in water and produces both cation & anion. This detergent –a) posses affinity to wool and cellulose fibres. B) Has lubricating properties. C) Behave like anionic in the alkaline solution.

4. Non-ionic Detergent: When dissolved, get oriented at the surface and reduce surface tension. Don’t get ionized and contains hydrophilic head and hydrophobic tail.

Here Hydrophobic means it does not attract the water and the Hydrophillic means it attracts the water.

What is Surface Active Agents or Surfactant Used As Textile ChemicalsDefinition of Surface Active Agent: Surfactant or Surface Active Agents can be defined as the textile chemicals, which-

1. has balanced solubility in water and in oil.2. preferentially gets oriented at the interface between air and water in which it is dissolved.3. lowers the surface tension of water substantially. When dissolved in it in the concentration

range 0.1 – 10 g/L at the room temperature which is 27 to 30 degree centigrade.

Classification of Surfactant or Surface Active Agents:

Chemistry of Surfactants

Surfactants is of two kinds – 1. Ionic Surfactants. 2. Non- Ionic Surfactants.

Ionic Surfactants is of three kinds like 1. Anionic Surfactants, 2. Cationic 3. Amphoteric.

Ionic Surfactants :

Anionic, Cationic & Amphoteric Surface Active Agents are called Ionic Surfactants or Surface Active Agents.

Anionic Surfactants:

It can be defined as those surfactants which when dissolved in water ionize into long Anions and small cations.

Cationic Surfactants:

Cationic Surfactants can be defined as those surfactants which when dissolved in water ionize into long Cations and small Anions.

Amphoteric Surfactants:

Amphoteric Surfactants or surface active agents are those agents which when dissolved in water ionize and produce large segments carrying both anionic and cationic charges.

Non-Ionic Surfactants:Non-Ionic surfactants are those surfactants which are soluble in water and reduce the surface tension of water, but, they do not generally ionize when dissolved in water.

How to Select Proper Reactive Dye For Dyeing?

Properly Dyestuff Selection for Reactive Dyeing:

Reactive Dyestuff Selection:

The selection of reactive dyestuff for a tri-chromatic or bi-chromatic combination plays a very important role in the performance and reproducibility of reactive dyeing in textile processing. There are some crucial Points that should be in your head while you are selecting the reactive dyes for dyeing fabric.

Solubility Characteristics of Reactive Dye:

Solubility of individual dyestuff in g/l without salt (straight) and with salt should be checked importantly to dye selection for a combination shade. In a tri-chromatic combination, all the reactive dyes should have almost similar solubility characterized. The reactive dyestuff that gets affected by the presence of salt would, a) produce tonally different shade,b) produce poor rubbing and wash fast dyeingc) batch to batch difference in depth and tone would result.

You must consider the following things while reactive dyeing:

Using of Primary Colors:

One should try to use the Basic Colors such as Red, G.Yellow and Blue. The secondary colors should be avoided as far as possible.The Red’s and Blue’s varies with shade and requirement of fastness properties.

Dyes with similar Exhaustion and Fixation values:

The Reactive dyeing takes place in three steps. viz.,1. Exhaustion2. Fixation3. Wash offNormally two types of exhaustion take place while dyeing. These are primary and secondary exhaustion.Primary Exhaustion is the amount of dyestuff migrated on the substrate in the presence of salt. While secondary exhaustion is the total amount of dye migrated on the substrate in the presence of salt and alkali.While selecting a combination, one has to ensure that the Percentage Exhaustion (PE) and The Percentage Fixation (PF) of dyes should be similar.In the case ofReactive ME Dyes PE is 60 to 70%Reactive HE dyes PE is 70 to 80%Reactive VS dyes PE is 40 to 50%If is always preferable to use dyes with PE about 60 to 70%, i.e., ME dyes. Patchy dyeing may occur if peoper care is not taken while using dyes with higher PE, or lower PE.

Dyes With Similar Affinity:

Generally the dyes are classified as Low, Medium, High and Very High affinity dyes.For Exhaust dyeing, High and very high affinity dyes and preferred. Where as low affinity dyes are used in continuous dyeing.

If you follow the above steps you will be able to properly select reactive dye.

Factors Affecting the Choice of Dyeing Methods in TextileThe following is a list of factors which dictate the choice of conditions under which particular blends might best be dyed:

1. Coloristic effect required. Check is it union, serve, tone-in-tone or what-else? Ask your buyers that what he wants from you and dye the fabric or any other textile materials as per buyer requirements.

2. Colorfastness required of the resultant dyeing. It is worth mentioning that – before starting a dying process in textile you must have to ask your buyer that, what type of colorfastness property he/she wants. Use grayscale to measure the colorfastness of the sample that you have dyed and let the buyers informed about it.

3. Suitability of the dyeing for subsequent finishing processes. Finishing is the crucial point to consider. Every dyeing process might have different finishing process. Check what kind of finish you can serve.

4. Compatibility of dyes from different application categories with one another. Blended fiber or Blend textile requires particular and fiber specific dyes to be properly dyed. It is seen that; if you use usual dyestuff to make a blended fiber or blended fabic dyed, then some parts of that fabric has been dyed and some other parts haven’t been dyed.

5. Availability of particular types of batch, semi-continuous and continuous dyeing equipment. If you don’t have the required instruments, materials, dyes and batches; how would you dye? So, check and dye the fabric or fiber if all of the required instruments and materials are available.

6. Cost of the dyes and chemicals involved. It does totally depend on the buyers and on the services you give. If your buyers want a blended dyeing with good color fastness and good conditioned; then you might have to rush to buy good chemical and good dyes. And most importantly; good services mean producing good product by using good materials. So it varies the cost.

7. Economics of the overall process. The last thing one must have to consider; which is Money. How about your budget? How much money do you want to spend to dye these fabrics or fibers?

Some or all of these points should be involved in any decision to proceed with a particular method of dyeing a given blend.

How to Mordanting, Fixing and then Dyeing the Textile Fibres?Cellulose Fiber has no affinity for basic dyes. So chemicals are applied (Mordanting Process) to create affinity in Cotton Fibre Dyeing.The fibre Dyeing Sequence is as follows:

Mordanting

Firstly use Tertaremetic Acid. Then use Fibre+ Tannic Acid Fixation to create Tannin Mordanting Cellulose. In this cases the alternating synthetic mordents may be used.

Mordanting Fixing:

Tannic Acid=4% Tertaremetic Acid=2%M : L= 1:20 M : L = 1:20Time = 2 hrs Time = 30 MinTemp = Boiling Temp= Boiling

3. Dyeing:

Dye→1%M : L→ 1 : 20Time → 1 hrsTemperature → above 70◦

By following above mentioned three steps the Textile Fibre is dyed usually which have no affinity to dyes directly.

Different Dyes Which Are Used To Dyeing The Fabric & YarnDyeing Fabric using different dyestuff is the most common things that every Textile Engineers should have to know. There are many kind of dyes are used to dyeing fabric. Maximum of them are suitable for fabric dye and yarn dyeing.

Dye staffs used to fabric dyeing are:

Direct dyes:

These dye staffs are generally sodium salt of sulphonic acid. They have direct affinity to cellulosic fibre. They are water soluble and needs salt addition in the dye bath. Should be applied at alkaline or neutral condition. Poor fastness to wash but cheaper for fabric dyeing.

Basic dyes:

These are generallyu ammonium, sulphonium or a uxonium salt. Famous for bright shade during dyeing fabric. Water soluble and application on cotton and other cellulosic fibre and leathers.

Acid dyes:

chemically acid dyes belongs to various subclasses such as nitro nitroso, monoazo, diazo, xanthance azine, quinoline, anthraquinone etc. they are water soluble and have affinity to wool, silk and nylon fibres to dyeing. They are applied to the fibres through neutral or acid dye bath.

Mordant dyes:

They are the oldest natural dyes. They have no affinity to textiles but can be applied to cellulose or protein fibres in order to dyeing fabric when they have been mordented previously with metallic salt. These dye staffs are capable of combining with metallic oxides to form insoluble colour on the fibre .

Sulpher dyes:

These are complex organic compounds containing sulphur. They are insoluble in water but sluble under reduced condition . they are usually applied cotton for cheaper shades, have high wet fastness but poor light fastness during dyeing fabric.

Azoic dyes:

These are not ready made dyes. Fibres are firstly impregnated with a coupling component like bita nepthol and then combined with a diazotized base to producer insoluble dye staffs into the fibre. Their main use on cotton but also can be used to dyeing wool silk and fur.

Vat dyes:

These are very fast color on cotton and insoluble in water. They are reduced by strong reducing agent to pr9oduce leuco vat and at this stage they are soluble in water. After impregnation they are again oxidized to their original insoluble form.

Reactive dyes:

These dye staffs directly combinds with cellulose by chemical bonding i.e. covalent bonds are produced. They have excellent wash fastness. Mainly used on cotton dyeing . can also be applied on wool, silk and nylin dyeing. Dyeing is carried out in an alkine bath.

Disperse dyes:

These dye staffs are very suitable for synthetic fibres for example polyester, nylon, acrylic, cellulosic acetate, etc. high temperature dyeing methods are suitable for these dye staffs but carrier dyeing method can also be applied.

In the above mentioned dyestuff, the Reactive Dyestuff is mostly used in today’s Textile Industry.