Anti crease finishes1.pptx

finishing of texties

1. ANTI CREASE FINISHES

2. Definition The ability of a fabric to resist the formation of crease or wrinkle when slightly squeezed is termed as crease resistance. The ability of a fabric to recover to a definite degree is called crease recovery of the fabric.

3. Crease resistant finish : A crease resisting process in which resins are formed inside the fibre was developed for making the materials anti crease. This makes them resist deformation and enable to recover from crumpling without affecting the inherent qualities of the fabric such as drape etc. The trade name is Tebilised fabrics.

4. This finish is used to bring the improvements in the fabric such as reduced tendency to shrinkage, better handle and feel, increased dry and wet strength. Easy care finishes There are three types of easy care finishes, Anti-crease finishes Wash and wear finishes Durable-press finishes

5. All the above finishes are produced by similar technique. The fabric is treated with a precondensate of a resin or a cross linking agent in the presence of a catalyst followed by curing to set the resin or to form cross links or both.

6. Wash and wear fabrics are those which after washing can be dried and the garments made from them can be worn without ironing or pressing. This finish imparts crease recovery only and is un-suitable where pressed in creases are required or where the formation of sharp creases during ironing is hindered.

7. For shape retention and freedom from ironing, the fabric is given a durable press or permanent press finish which after washing and drying retain their shape permanently. Curing is done after the garment has been cut, sewn and pressed to shape.

8. The following are some of the cross linking agents mostly used for crease resistant finishing. DMU (Di methylol Urea) DMEU(Di methylol Ethylene Urea) DMDHEU(Di methylol Di hydroxy Ethylene Urea) DMPU(Di methylol Propylene Urea) TMM(Tri methylol melamine/Melamine formaldehyde

9. Under neutral or slightly alkaline conditions urea and formaldehyde condense to give monomethylol urea ( MMU ) or dimethylol urea ( DMU ). These products are known as precondensates are used to deposit the resin in the fibre. Prepared by treating 100 parts of formaldehyde adjusting its pH to 7 by adding caustic soda, with 44parts of urea raising the pH of the mixture to 9 with caustic soda and add equal amount of water. Anti-crease finish (DMU)

10. Heat the mixture to 80 º c for 15 min and then cool it rapidly. Molar ratio of urea to formaldehyde is 1:1.6. The fabric is padded with the precondensate solution (100 to 300 g/l solid content) containing an acid catalyst like ammonium chloride with upto 70% pick up.

11. It is dried carefully on a stenter at 80 º c and cured at 150 º c for 2 to 3 min. The synthetic resin is formed by polymerisation and is deposited in the fibre forming a three dimensional structure, thus becomes crease resistant.

12. Urea formaldehyde resins (DMU )   Highly reactive. It has to be used within a few hours in the finishing bath. Low stability to hydrolysis, low durability to laundering. High Chlorine retention. High content and release of formaldehyde. Very high elastic resilience. End product: DMU  

13. Anti-crease garment

14. These finishes are based on cyclic ethylene ureas and triazone and constitute the second stage of progress in easy-care-finishes. Ethylene urea is dissolved in formaldehyde (molar ratio 1:2) to give dimethylol ethylene urea(DMEU) which does not contain –NH- groups, which cause chlorine retention. Wash and wear finish

15. The cloth is padded with a diluted solution of DMEU containing a non-ionic softener and a catalyst (diammonium hydrogen phosphate); polyethylene emulsion is added to the pad liquor to improve tear strength and abrassion resistance. The fabric is dried and cured at 150 º c for 3 minutes and washed with an anionic detergent (3 g/l) and soda ash (4 g/l) at 60 º c for 10 minutes and then rinsed with hot water first and then with cold water .

16. DMEU directly reacts with cellulose and is highly effective in producing crease resistance of wash and wear type with good chlorine resistance. DMEU treated fabrics have high crease recovery angles( 250 to 260) It gives a soft handle and the finish is fast to washing.

17. Triazone formaldehyde condensates give excellent crease recovery and wash-wear properties. Triazones are prepared by reacting urea, formaldehyde and aliphatic amines. Addition of ethylamine to dimethylol urea (dmu) gives triazone (urea 1 mole, ethylamine 1 mole and formaldehyde 4 moles).

18. Before application dimethylol triazone is diluted with water and other ingredients like non-ionic wetting agent, poly ethylene emulsion and catalyst are added. The fabric is padded with above liquor, dried at 90 º c and cured at 150 º c for 4 minutes, then washed with a non-ionic detergent (3 g/l) and soda ash (4 g/l) at 60 º c for 15 min and rinsed with hot and cold water.

19. Wash and wear garment

20. In durable press, the fabric is impregnated with high concentration of resin and cured at high temperature for a longer time. Dihydroxy dimethylol ethylene urea type resins were the first to be used for this purpose. Dimethylol propylene urea ( DMPU ), dimethyl hydroxy ethylene urea ( DMDHEU ) and ethyl carbamates are the only resins being used successfully for durable press treatment . Durable press finishes

21. Because of the combination of high resin content and prolonged curing at high temperature, there is loss in strength and reduction in abrassion resistance of the fabric. The fabric is first impregnated with a cross linking agent and a catalyst. It is then delivered to the garment maker. Drying is carried out in such a way that only partial cross linking takes place.

22. The garment is then fabricated and the creases or pleats are inserted and are made permanent by hot pressing and curing at the appropriate temperature. DMDHEU is most commonly used for this purpose. Dimethylol ethyl carbamate has been successfully used for deferred cure technique. durable press process 1 . wet fixation process or polyset process 2. curing process

23. The resin is first fixed and the fabric is kept in a batch on a rotating roller at 70 º c for 2 hours, then washed and dried. It is then again padded with a catalyst (zinc nitrate as a cross linking catalyst) and zirconium acetate (as polymerisation catalyst) and dried. After stitching the garment and hot pressing the shape and creases, it is cured at 160 º c for 10 to 15 min.

24. Recipe for deferred cure process for a heat-set blended cotton/polyester fabric: 10-12 % cross linking agent 0.5-1 g/l wetting agent 3-4 5 catalyst (mgcl2.6h2o) 1-10 g/l additive (polyacrylate emulsion to improve abrasion resistance) The goods are impregnated with the carbamate, a catalyst, a wetting agent and an additive to improve abrassion resistance.

25. They are then dried in a stenter and stored for 4 to 6 months. Within this period the fabric is cut and made into garments, creased and pleated into shape carefully with a hot iron. Finally the garment is cured at 160 º c for ten minutes, washed and dried.

26. Durable press finished products

27. Glyoxal Resins N,N-Dimethylol-4,5 dihydoxyethylene urea (DMDHEU ) This chemical is the basis for about 90% of easy-care and durable press finish products on the market . DMDHEU is synthesized from urea, glyoxal and formaldehyde . It is less reactive than DMU and TMM and therefore requires more active catalyst . It is more stable than finish baths with DMU and TMM.

28. Main properties of DMDHEU products Low to very low reactivity (when ether modified ). Excellent durability and laundering. Low chlorine retention. Medium to very low formaldehyde release. The most commonly used durable press products.

29. DMEDHEU doesn’t contain formaldehyde. It is synthesized from the relatively expensive N,N-dimethyl urea and glyoxal. They are less reactive than DMDHEU types because of their hydroxyl groups . Stronger catalysts or harsher reaction conditions are needed for successful crosslinking. Non-formaldehyde products (DMEDHEU)

30. DMEDHEU costs about twice as much as DMDHEU products. In order to achieve comparable easy-care and durable press effects to DMDHEU, nearly twice the amount of DMEDHEU is needed. However, a 1:1 mixture of DMDHEU and DMEDHEU is popular because of its reduced formaldehyde levels with slightly inferior physical properties at an acceptable cost.

31. M ain properties of DMEDHEU products Formaldehyde free. Very low reactivity. Very low chlorine retention. Limited durability to laundering. Yellowing effect when not ether modified. Development of unpleasant odors, depending on the product formulation.

32. The reaction of DMDHEU with cellulose requires an acid catalyst for acceptable yields under conditions suitable for textile processing. The most common catalysts are Lewis acids such as magnesium chloride and zinc nitrate that generate acid conditions during curing process, thus providing neutral liquors and good finish bath stability. Catalysts for easy-care and durable press finishes

33. Sulfuric and hydrochloric acids and their ammonium salts serve as excellent catalysts but also lead to undesirable fiber degradation.

34. It improves the Crease Resistance and Crease Recovery property. It reduces the shrinkage of the fabric during laundering. It imparts a smooth and quick drying property. It improves Resilience, Handle and Draping quality. It improves the weight and Dimensional stability. Advantages of finishes

35. It increases the strength of RAYON in both wet and dry state. It gives resistance to degradation by light and laundering. It improves the fastness to Light and Washing of many dyestuffs. It prevents the Inter molecular slippage in the fiber core. It becomes partially water proof and Rot proof.

36. An unavoidable side effect of the cellulosic crosslinking finishes is reduction in elasticity and flexibility of the cellulose fibers . This produces a considerable decrease in abrasion resistance, tear and tensile strength on cellulose. Disadvantages