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Creponarea

Creponarea materialelor din bumbac in mediul alcalin

Operatia se aplica tesaturilor din bumbac 100% caracterizate prin legaturi tip panzaintre fire.Prin creponare se realizeaza o fixare a tesaturii intr-o anumita forma.

Efectul obtinut cu agentii de umflare, cu NaOH concentrat, trebuie sa fie rezistent in

timp, la un numar ridicat de spalari.

Principiul creponarii alcaline

Pe tesaturile usoare de bumbac, la sfrsitul pregatirii sau al fluxului complet de finisare

(material vopsit sau imprimat) se imprima in directia urzelii dungi de NaOH concentrat. In locurile

imprimate cu astfel de solutie, tesaturile se umfla si se contracta iar in spatiile netratate cu solutie

alcalina, fortele de contractie diferite realizeaza suprafata creponata.

Tehnologia creponarii alcalineEfectul de creponare poate fi obtinut pe o masina de imprimare cu o singura culoare si

anume: se imprima in dungi in directia urzelii, cu solutie de NaOH concentrat (38 OBe) adus la

vascozitatea corespunzatoare cu aglutinant.

In compozitia pastei de imprimare se gasesc: hidroxid de sodiu 38OBe sau 441g/l; monagum W

2,5%; solvitase 3% si star Keater WJ 3,5%.

Fixarea concentratiei pastei de imprimat se realizeaza cu apa rece. Urmeaza agitarea si

fierberea pastei.

In locurile fasiilor imprimate cu pasta alcalina, tesatura se contracta din cauza umflariisi firele se apropie intre ele. In locurile neatinse, fortele de contractie onduleaza tesatura formand

astfel suprafata creponata. Patrunderea si actiunea NaOH concentrat necesita timp si tesaturaimprimata este depozitata 30 minute. Aceasta operatie are loc pe banda de relaxare cu trei nivele.

O altă reţeta utilizata pentru creponare este:

-  440g/l NaOH (soda caustica);-  Prisulon CMS10 (Starch ether) 

-  timp de 30-45 min

Caracterizare substanţe folosite : PRISULON CMS 10

Starch ether(flakes)

Universal thickener as colour-intensify additive with other thickeners. Versatile use,good stability to alkali. Combined with other thickeners in printing with vat, disperse,

acid and direct dyestuffs.

applicatiom amount:9.0-10.0% in stock

50.0-60.0g/l¸ in the print pastepH in stock:9.5-11.5

ionic charcater:anionic

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Dupa ondularea dorita, NaOH inactiv si aglutinantul se indeparteaza prin spalare in bazine tip haspel

urmand apoi clatirea si neutralizarea. Tesatura este purtata prin aceste bazine sub formanetensionata, in forma de funie. Urmeaza o neutralizare care are drept scop indepartarea mediului

alcalin de pe material supus operatiei de gofrare. Aceasta operatie se efectueaza pe o masina de

spalat in foaie lata cu mai multe cazi. In primele cazi se raalizeaza o spalare cu apa calda 40-50OC, o

spalare cu apa rece dupa care neutrlizarea propriuzisa se face in cada a treia cu solutie de 10g/lCH3COOH. Indepartarea CH3COOH de pe material se face in urmatoarea cada prin spalare cu apa

rece.

Dupa neutralizare urmeaza uscarea pe rame, sub forma de foaie intinsa in latime, cu oconducere de 18% avans in lungime, pentru asigurarea efectului de creponare. Temperatura

aerului in camera de uscat este de 120-130OC, iar viteza de deplasare a tesaturii este de 30m/min.

[20, pag.328] Utilajul folosit la operatia de creponare este masina de imprimat cu cilindriigravati.

Etape:1.  Imprimare pe o maşină de imprimat (cu cilindri gravaţi sau cu şabloane

plane);

2.  Depozitare 30- 45 minute)3.  Spalare la 40-50 ˚C (sub formă de funie)

4.  Clătire rece (sub formă de funie) 5.  Neutralizare cu 10 g/l acid acetic (sub formă de foaie lată) 

6.  Clătire cu apă rece

7.  Uscarea pe ramă la 120-130˚C (cu 30 m/minut) 

Caracterizarea substanţelor folosite

Monagum

Monagum is, according to PRO Chemical & Dye, a modified starch gum that is the only

thickener for discharge printing with hypochlorite ("chlorine") bleach that stays thick, rather than

breaking down and becoming thin quite soon after mixing with the bleach. We do not use it tothicken reactive dyes.

Starch is not used

Starch, a polysaccharide which is used as a thickener in foods, is not used with reactive dyes.

This is because the starch will itself react with the dye, resulting in lower color yields; dyed

starch may also loosely bind to the fiber, washing out only gradually over the course of manywashings and making it appear as though the dyed fabric is not washfast. In theory, starch could

be used with acid dyes, but I have never seen this recommended.

Methyl Cellulose

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Methyl cellulose is a thickener commonly used for marbling. The water is thickened with methyl

cellulose so that it will support fabric paint which is floated on top of it.

Methyl cellulose can also be used to make print paste for acid dyes. You might be able to find it

in a specialty wallpaper shop under the name of 'cellulose adhesive.'

Guar gum

Guar gum is another thickener that is commonly used (in more purified form) in foods. It is used

to thicken the caustic paste used to make devoré patterns on mixed fibers. It is not used with

fiber reactive dyes such as Procion MX because it reacts with them, competing with the fiber thatis being dyed, but it is used to thicken vat dyes and acid dyes. See ProChem's recipe for Colored

Discharge Printing using PRO Vat Dyes. Guar gum is superior to alginate in thickening Lanaset

dyes.

Print Paste

PRO Chemical & Dye sells two convenient sodium alginate mixtures, PRO Print Paste Mix Fand PRO Print Paste Mix SH. Pro Print Paste F (for silk) contains urea, low viscosity alginate

and metaphos, while Pro Print Paste SH (for cotton) contains urea, high viscosity alginate and

metaphos. (Metaphos is ProChem's name for the water softener, sodium hexametaphosphate).

SOLVITOSE™ FC 100

Solvitase FC100 is a revolutionary starch-based additive for earth moist concrete.

SOLVITOSE™ FC 100 chiefly works as a thickener. A high water-cement ratio can be used

without loss of green strength, creating a stable mix and allowing the cement to hydratecompletely. The blocks retain their shape and the process is less sensitive towards variations in

water content.

Because the water volume is less critical, it is much easier to control the manufacturing process.

Moreover, since compactibility of the concrete is improved, the product moulds can be removedsooner, and less vibration and tamping are needed. As a result, production speed increases and

machinery wear is reduced.

330 grams of SOLVITOSE™ FC 100 per cubic meter of concrete is sufficient to get excellentresults. Special, easy-to-use dosing equipment is available.

Thorough testing in real manufacturing situations proves that SOLVITOSE™ FC 100 lives up toall the promises.