Lenzing Processing

7/31/2019 Lenzing Processing

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Technical lecture:

Karin Kmpf

Customer Service

Lenzing AG - AUSTRIA

Dyeing & finishing of Lenzing speciality fibres


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Preparation, Dyeing and Finishing

TENCEL Standard by Enzym process (Air jet / Rope tumbler)

TENCEL

Standard by Resin Beat (Air jet / Rope tumbler)

TENCEL LF and TENCEL A100 Dye only (Softflow, Overflow, Jet)


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Expectations on the fabric aspect

TENCEL Standard

Cool and silky fabric aspect with no fabric hairiness

Faintly hairy fabrics with a minor bulky aspect

TENCEL LF and TENCEL A 100

With a slightly hairy fabric aspect giving a warm and bulky handle


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Different surface aspect

fibrillated hairy


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Fibrillation

undesired fibrillation

(fuzziness)

desired fibrillation

(peach skin)


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Fuzziness - primary fibrillation


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Peach skin - secondary fibrillation


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Clean surface after enzyme treatment


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TENCEL Standard / TENCEL LF/ TENCEL A100

Process overview of chemical properties

Technical Benchmark TENCEL


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Detailed discussion of processes andgeneral recipes for jersey knits

Preparation:

Heat-setting (Elastane blends)

Scouring

Alkaline peroxide bleaching

Reductive bleaching

Combined Bleaching system (oxidative/reductive)

Rinsing after preparation


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Dyeing:

Parameters for discontinuous dyeing

Why TENCEL A100 is different

Rinsing after dyeing


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Finishing:

Importance of fabric pH

Obtaining a clean surface

Optimum Wash Pilling performance

Optimum ICI Pilling performance


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Routes to achieve a clean fabric

Resin Beat (Mechanical Polishing) - TENCEL Standard

Air Jet / Air tumbler (with resin finsh)

Standard discontinuous process - TENCEL LF or TENCEL A100

Softflow or Overflow Jet


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Resin Beat - Mechanical Polishing

TENCEL Standard

Machine: Process:

Air Jet Scour and Primary fibrillation

Air Jet Rinse and neutralise

Air Jet DyeingAir Jet Rinsing, neutralising, soaping (pH check fabric)

Stenter / Dryer Dimensional control

Pad + Stenter Apply resin and catalyst (approx. pH 4.5)

Stenter / Hotflue Resin Cure: temperature and time = f (resin)

Air Tumbler Defibrillation = Dry tumbling, 400-800 m/min

Pad + Stenter Top softening: application of softeners

Result: Excellent clean fabric with good wash performance


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Dye Only: Softflow / Overflow Jet

TENCEL LF and TENCEL A100

Machine: Process:

Softflow Scour

Softflow Rinsing and neutralising

Softflow Dyeing

Softflow Rinsing, neutralising, soaping

Softflow Application of softeners

Stenter Drying: Dimensional control

Sanfor Optional: Dimensional control, fabric touch and lustre

Result: Clean fabric with good wash performance

Result affected by yarn quality, jet processing conditions and overall time +

chemical auxillaries


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Technical Benchmark TENCEL


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Preparation of TENCEL Jersey Knits


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Heat-setting

TENCEL Blends with Elastane

What is the recommended temperature for the elastane type used?

Typically: 190C approx. 45 sec

Material construction: Fusing effect in jersey knit constructions

22 dtex Elastane, 1:1 knitting construction (1 course TENCEL, 1 course

elastane), heat-setting will achieve a fusing effect between the elastane

filament with the adjacent TENCEL

yarns, producing a more stable fabric


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Scouring

Temperature 85-90C

Non-ionic or anionic washing agents

At neutral pH or with soda ash

Rinse properly if using soda ash in scour

Jersey knits - Possible substances to be removed:

Silicone oils, waxes and parafin, knitting oils


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Alkaline Peroxide Bleaching

Temperature 85-90C

Soft water or hard water without catalysts


Alkali: soda ash or caustic soda (low quantities of caustic)

Peroxide stabilising agent (optional addition of Mg chloride or sulphate

Do not use standard cotton bleaching recipes

TENCEL LF


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Alkaline Peroxide Bleaching

Temperature 80C

Soft water or hard water without catalysts


Alkali: soda ash (A100 is sensitive to caustic soda)

Peroxide stabilising agent (optional addition of Mg chloride or

sulphate)

Generally not blended with cotton


TENCEL A100


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Neutral Reductive Bleaching

Temperature 80 - 85C (Type: Blankit IN)

Soft water


Neutral pH (7-8) No hydro and caustic soda for LF or A100

Full White: Optional addition in 2nd stage of combined bleaching

system, oxidative + reductive, optical brighteners

Tencel LF / cotton blend: Full White with optical brighteners


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Combined Bleaching System

1st Step - Peroxide 2nd Step - Neutral Reductive Bleach

Full White: oxidative, reductive + optical brighteners


Consider the chemical resistance of the blended fibre

Cotton / TENCEL LF


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Dyeing of TENCEL Jersey Knits


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TENCEL LF

Procedures: Isothermal, Migration, Temperature rise

Temperatures: 50C, 60C, 70C, 80C, (90C for migration)

Stable to all alkaline systems and concentrations used for reactive dyeing

Use anti-creasing agent in dyeing and soaping baths


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TENCEL A100

Procedures: Isothermal, preferably Migration process

Temperatures: preferably 80C (90-95C for migration)

Stable to all alkaline systems and concentrations used for reactive dyeing

Use anti-creasing agent in dyeing and soaping baths

Note the higher exhaustion speed of TENCEL A100,

- decrease salt concentration

- extend dosing times


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Reactive Dye 60C

0

10

20

30

40

50

60

70

80

90

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106 113 120 127 134 141 148 155 162 169 176 183 190 197 204 211 218 225 232

time

exhaust%

TENCEL A100

TENCEL LF

TENCEL St.

Cotton

TENCELA100

Dyebath exhaustion: LR 50:1 Note different higher exhaustion


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Reactive dyeing summary

Use dye migration methods. Consider higher liquor ratio

Dyes with high reactivity and low to medium substantivity:

- longer dosing times (alkali), less salt (dosing of salt)

Dyes with lower reactivity and medium to high substantivity:

- decrease salt concentration, dosing of salt

- Longer dosing of alkali

pH control at the beginning of dyeing

Soft action jet

TENCEL A100:


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Reactive Dyeing: Aftertreatment

Rinse directly after dyeing to remove main quantity of salt and alkali

Neutralise:

- TENCEL LF at 30-35C (low temperature is important)

- TENCEL

A100 at 30-50CRinse at 50C to remove the acid liquor

Soap Off: 100% TENCEL fabrics only need 90C for soaping

Rinse after soaping at 60 to 80C

Soften


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Rinsing Process:

Soft water liquor pH fabric pH

Dye bath end

1st rinse 50C 5 min

2nd rinse 50C 5 min

3rd rinse: acidifying 35C 20 min check at the end

4th rinse 50C 10 min

5th rinse: soaping 90C 10 min neutral

6th rinse: 70C 10 min7th rinse overflow 5 min

8th rinse 40C 15 min neutral

Acidifying: x ml/l acetic acid 60%


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Important Points: TENCEL LF & A100

Preparation: Use only well stabilised peroxide bleaching systems andrecommended bleaching temperatures & alkali concentrations

Reactive Dyeing:

check pH of fabric before dyeing

allow for the higher and quicker dye-uptake of TENCELA100

Aftertreatment:

Alkali is trapped in the core of TENCEL fibres. Longer neutralisingtime required: 15 to 20 min

Use low neutralising temperature, 30-35C only, for TENCEL LF

Soap off at 90C for 100% TENCEL fabrics

Softening: Non-ionic hydrophilic softeners are recommended

Check pH of fabric according to AATCC Test Method 81 or DIN 1413 (pH7 - 7,5)


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Finishing of TENCEL Jersey Knits


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First check: evaluation of fabric pH

Morapex: Hot Water extraction: short time, reliable

DIN 1413: Room temperature extraction: long time, reliable

AATCC Test method 81: Boiling extraction: medium time, reliable

Check two samples for a more reliable result


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Yarn properties - Hairiness of yarn

Singeing of knitwear

Gentle Discontinuous Treatment / Wet Processing

Chemical Finishing and Resination

Clean surface (General parameters)


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Reduce machine loading, higher liquor ratio

Processing speed, as fast as necessary or as slow as possible

Start loading the machine at 50C (wet stiffness), load slowly

Use anti creasing agents for Preparation and Dyeing

Check all your processes: reduce overall time if possible

Prefer processing in tubular form: better rope reorientation

Use softflow machines

Turn the tube, face side inside

Clean surface (Wet processing)


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Chemical Finishing and Resination

Crosslinking Polyurethane

Non-ionic hydrophilic softeners

Polyethylene softener - optional

Silicone softeners - optional, but only small quantities

Combination with cross linking resin product gives the best effect

Clean surface (Finishing Parameters)


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Factors to be considered for the resination of TENCEL standard fabrics

Check pH value of fabric before resination: pH 6,5

Check the active content of your resin product

Check the actual wet pick up of your fabrics

Do not use citric acid as an additive to adjust the pH value

Using 2 separate passages for drying and curing helps achieve a proper

resination effect

Check to determine the exact fabric temperature whilst curing

Finishing Parameters


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Wash Pilling: Optimum performance

Decrease hairiness of yarn

Singeing of knit

Gentle Discontinuous Processing

Resin + crosslinking Polyurethane finish

Contact your auxiliary supplier for pre-trials on TENCEL fabric


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ICI Pilling: Optimum performance

Decrease hairiness of yarn

Singeing of knit

Gentle Discontinuous Processing

Resin + optional crosslinking Polyurethane finish

Higher resin quantity - optimum curing conditions

Additives: Polyethylene and Silicone compounds

Contact your auxiliary supplier for pre-trials on TENCEL fabric


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Summary TENCEL Jersey Knits


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Technical Summary

Chemical Fiber Properties: TENCEL LF & TENCEL A100

Processing Limits: peroxide bleaching

Processing Routes & Machine Facilities

Clean, Peach and Casual Peach

The Final Product: Consider and check all technical issues

Preparation - Dyeing - Finishing


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TENCEL A 100

Singing

Prewash neutral / soda ash 85-90C

Bleaching 90C ! x

Bleaching 98C / 120C x

Neutral reductive bleaching

Reactive, direct dyeing

PES, PA, WO dyeing

Stripping with Hydros and caustic soda x

Finishing - improve utility values !

Causticising / Mercerising


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TENCEL LF

Singing

Prewash neutral / soda ash 85-90C

Bleaching 90C !

Bleaching 98C / 120C x

Neutral reductive bleaching

Reactive, direct dyeing

PES, PA, WO dyeing x

Stripping with Hydros and caustic soda ! x

Finishing - improve utility values !

Causticising / Mercerising x


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Customer Service Lenzing AG

Tel. +43 7672 701- 3448

Fax.+43 7672 701- 3222

Email: [email protected]

http://www.lenzing-fibers.com/news

Lenzing Processing

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