Thickener in Textile Printing: Types, Function, Role and Uses

Md. Amir Khasru
B.Sc. in Textile Engineering
Department of Yarn Engineering, SARSTEC
Email: [email protected]

Introduction:
Textile dyeing and printing is moving very fast towards new design and fast fashion. It is a part of textile wet processing industry. To ensure textile sectors new demand, textile should focus new trends. Thickener is an auxiliary, substances that are used in textile printing and dyeing. Thickener in textile printing possessed 60-70% weight of total print paste. It used to hold colorant on to the fabric surface.

Definition of Thickener:
Thickener is a thick material, added to liquids to make them more viscous without significantly altering their other characteristics. In terms of textiles, thickener is an adhesive that is used to create viscous printing pastes in water. It is important to impart % plasticity.

Function of Thickener in Printing:

• To provide the desired viscosity to the printing paste.
• To keep hold and fixed dye molecules & the ingredients of the printing paste on the fabric surface.
• To stop the printing paste from leaking and spreading.

Types / Classification Thickener in Textile Printing:

1. Natural thickeners: Natural thickeners are extracted polysaccharides from plant exudates, seaweeds, seeds, roots and such as other natural sources. Starch, derivative of starch, soluble cellulose derivatives and gums are most effective natural thickener in printing.

a) Cereals starch:

1. Maize starch
2. Wheat starch

b) Plant exudates:

1. Gum tragacanth
2. Gum Arabic
3. Karaya gum

c) Root & seeds:

1. Guar gum: It is a thickener agent, an organic gum that is obtained from the guar seeds.
2. Locust beam gum

d) Sea weeds:

1. Na-alginate

2. Synthetic thickeners: A long-chain polymers with party cross-linked carboxylic groups is called synthetic thickeners. It can be tailored to a specific situation.

a) Acrylic:

1. Polyacrylic acid
2. Polyacrylic amides

b) Vinyl:

1. Polyvinyl chlorides
2. Polyvinyl acetate
3. Polyvinyl alcohol

3. Modified Natural thickeners: It modified from natural thickeners by chemical, physical & thermal methods. Bio-degradable materials are regarded as one of the most important areas of material engineering. It also has properties like transparency, good film-forming properties, high-quality thermal stability and mechanical and processing properties.

a) Starch derivatives:

1. British gum
2. C.M.C

b) Cellulose derivatives:

1. C.M.C
2. HEC

c) Gum derivatives:

1. Meypro gum
2. Indalca

Roles of Thickener in Printing Paste:

1. Viscosity control in textile printing: Thickener is used to maintain required viscosity of the printing paste. Ensure thickness that could easily fix in the fabric surface.
2. Print sharpness of textile printing: Ensure thickness for clear and well patterned printing in the fabric surface.
3. Adhesiveness of printing: It provides adhesiveness to the printing paste which prevents the colors from bleeding.
4. Pattern retention: In printing process, thickeners are used to draw extra-ordinary pattern onto surface. Thickener in textile printing helps to keep the colorant as pattern in the surface.
5. Wash and fastness: Thickener improves the fastness and wash properties of the printed fabric. Prevent from color extraction from fabric surface.

Qualities of Good Thickener in Printing:

1. In textile printing, the thickener has to be stable and work well with the dyes and auxiliary materials that will be applied.
2. A thickener has to have certain chemical and physical qualities, as well as the ability to moisten and adhere, viscosity, and flow characteristics.
3. Thickener used in textile printing needs to dry completely to avoid color bleeds on the fabric’s surface.
4. Thickener used in printing shouldn’t have any chemical or color affinity.
5. Because the thickening film transfers color while steaming, it should be simple to remove the used thickener.
6. Textile printing thickener must to be reasonably priced and easily accessible.

Paste Preparation of Thickener:
Wheat starch is the widely used as thickener in textile printing. It gives good workability than others. Keeping qualities, it may used either alone or in combination with other thickening agents like gum tragacanth. Wheat starch (10 – 12 %) forms a paste having thick consistency & allowing the dyes to penetrate into the fabric.

1. In the preparation of a 10% stock paste, 100 gm of the starch is stirred up with cold water by 4 ml of castor oil & 996 ml of water.
2. It is boiled with continuous stirring until a paste is obtained when the boiling is stopped and the paste is cooled with stirring

Selection of Thickener in Textile Printing:

1. Should have stability.
2. Must have some chemical & physical properties.
3. Good properties of dried film in thickener.
4. In steaming, proper extraction of water should be maintained.
5. No affinity to dye and no keeping of dyes from fabric.
6. It should be economical and also available.
7. Selected thickener in textile printing should be compatible with dyes and auxiliaries.
8. Simpleness of installation & removal

Working Procedure of Thickener in Textile Printing:

1. First of all, the thickener is mixed with water to give desired viscosity.
2. Other chemicals and dyes or pigment are added with thickener in textile printing.
3. Using various printing techniques like screen printing or roller printing is applied to the fabric surface.
4. Then the printed fabric should be dried to fix the print paste.
5. Finishing process used to improve color fastness, washing fastness.
6. In every process, we must ensure that the prints are sharp, vibrant, and durable.

Uses of Thickener in Textile Printing:

1. Thickeners are used to
2. Prevent bleeding or spreading of pastes.
3. Ensure precise, vibrant patterns.
4. Ability to adhere well to the fabric.
5. Support past to fix with fabric surface.
6. Give the fabric a good appearance with pigment or dyeing.

Conclusion:
Thickener is an integral part of the printing process. It offers stability, viscosity and precision to create vibrant durable prints. Wheat starch and plant gums are extracted from natural sources. Some are modified from natural thickeners and some are synthetically designed. Every types of thickener play a crucial role in modern textile design. To enhance the fabric appearance, thickener is important in printing.

Image courtesy:

1. https://ars.els-cdn.com/content/image/1-s2.0-S2405844024072554-gr1_lrg.jpg
2. http://www.ajindustries.in/textile-printing-thickener.htm

References:

1. A. Ebrahim , Ahmed G. Hassabo and Hanan A. Osman, Natural Thickener in Textile Printing
2. http://www.definetextile.com/2013/06/quality-of-good-thickener.html
3. https://en.wikipedia.org/wiki/Textile_printing
4. Lecture sheets of Emran Hossain, Assistant professor, BUTex.
5. https://textileengg.blogspot.com/2015/12/thickener.html

Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. He is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.

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