[1]General Size Proof and Recipe Recommendations for Desizing

Most errors occur during the pretreatment of sized woven goods.

These errors do not only occur because the kind of size is unknown, but also

the preparation layers, and the loom oils have to be taken into consideration

for the pretreatment processes.

Today, sizing agents are offered which satisfy all pretreatment technicians.

Nevertheless, many problems may be encountered when washing out these sizes.

During the washing processes it is very important to adjust to the correct pH-value corresponding to the kind of size, otherwise the size cannot e removed or will coagulate.

Further influence criteria:

- the washing temperature and washing time should be adhered to

- there should be a sufficient water exchange,

- the appropriate washing auxiliaries should be used.

Size analysis cannot be avoided to obtain an optimum pretreatment.

Therefore test methods which can be carried out in an industrial laboratory, without sophisticated analytical equipment are of great importance.

In literature we can find a great number of analytical procedures which are too complicated in practice, and which will not be explained in this brochure.

2.
Practice-orientated size determination

If the fibre composition of a sample is unknown it should be determined.. It will be mainly possible to predict the kind of size applied one knows the fibre type, but of course there are always exceptions.

On PES and PA-fibres only synthetic sizes will have sufficient adhesion.
Natural sizes such as starch and starch derivates and synthetic polymers will be found on cellulose fibres.

There are following examination possibilities to determine the size types:

-Size proof directly on the surface of the fabric
- Size proof in aqueous extract

The iodine test is a well known method to determine starch. When spotting iodine/potassium iodide solution on the material which has been sized with starch or starch derivatives it will show as an intensive dark-blue colour.
Polyvinyl alcohol sizes will also give a blue shade in this reaction, but this is a very greenish blue.

Preparation of a 0.1 N lodine/potassium iodide solution:

Due to the fact that the iodine can be contaminated by chlorine, bromine and cyaniodine and moisture one will take technical grade and will only prepare an approximate 0.1 N solution. For the preparation of a 0.1 N iodine/potassium iodide solution ampouls from Merck can be used, thus eliminating these possible impurities.

Preparing the Reagent:

12.8 g to 13.0 g iodine(equivalent weight 126.93)are placed into a litre measuring flask in which 20 to 25g KI free of iodine have been diluted in approx.50ml distilled water. The closed flask is shaken until all the iodine is dissolved, then distilled water is added to the measure-mark.

The iodine solution should be stored in a brown bottle, closed with a glass stopper in a dark and cool place. The bottle should only be opened for a short time when using the liquid because of the volatility of the iodine.

As already mentioned the PVA-size can be proved by iodine/potassium iodide solution. Small concentrations in size mixtures with starch cannot be determined because of its similar colour to starch indication. The spotting test with chromic acid/caustic soda has to be prefered because of this. There will be an indispotable brown staining with small concentrations of polyvinyl alcohol.

For this test chromic acid is dropped on the sample which is put on a glass plate. After 1-2min. 2-3 drops of a 50% caustic soda solution is added to the spotted area, only then are they rubbed with a glass rod. of polyvinyl alcohol is present it will become brown. if there is no polyvinyl alcohol there will be a yellow or green shade.

Preparation of chromic acid solution:

11.8 g potassium bichromate are diluted in 50ml hot distilled water while stirring. After cooling, add cautiously 25ml 98% sulphuric acid and re-cool. If sulphuric acid is added to orange coloured bichromate solution chromium trioxide will separate as red needles, but they will not interfere.

The cooled solution is stored in a brown glass bottle with glass stopper.

Due to the fact that chromium compounds are very poisonous the test with iodine, boric acid solution has to be prefered..

When spotting with boric acid solution dark brown to grey blue shades will develop in case of polyvinyl compounds.

Preparation of iodine-boric acid solutions:

20ml of 0.1N iodine solution(Merck) are mixed with 80ml of 1.4 dioxane and 1g boric acid is diluted while heating. The solution is cooled to 25¡Eand adjusted with 1.4 dioxane up to 100ml. 7ml water are added and then mixed.

Store in a brown glass bottle with glass stopper.

In some dyeing tests the sizes are not determined themselves but special components or final groups of the molecules. For example the reaction of basic dyestuffs with anionic groups in polyacrylate, polyester and polyvinyl acetate sizes. In most cases it is possible to distinguish between sizes on PES and PA fibres by combining different tests.

Application:

The dyeing tests are used to prove sizes based on:

-Polyacrylates
-Polyesters
-Polyvinyl alcohols
-Polyvinyl acetates

Realization of the dyeing tests:

1. Proof of polyacrylate-or Polyester sizes:

Reagent:1.0% acetic acid solution of BEZACRYL RED BL LIQ.50% or 0.5% acetic acid solution of Astrazon Red F3BL

A sample of approx. 10㎠ is put into the reagent solution until it is completely wet-out(approx.5sec.). Then the sample remains on the glass plate for about 30 sec. Then the sample is rinsed in a beaker with water (liquor ratio 1:500 up to 1:1000)during 60 sec. while stirring, it is taken out, dipped in fresh water for a short time(approx.2sec.)and finally dried on a glass plate in the air or in a drying cabinet at approx. 100℃.

2. Proof of polyvinyl acetate size:

Reagent: 0.01 N lodine-potassium iodide solution

A sample of approx. 10㎠ is put into a reagent solution until it is completely wer-out(approx.5sec.), then the sample remains on a glass plate for approx. 30sec. then the sample is rinsed in a beaker with water(liquor ratio 1:500 up to 1:1000)during 15sec. while stirring, it is taken out and air-dried on a glass plate.

Evalution of the dyeing test:

In the presence of polyacrylate or polyester size the sample treated according to 1. is stained from clear to intensive red, depending on the size concentration.

Polyvinyl acetate sizes will become red with BEZACRYL RED BL LIQ. 50%or Astrazon Red f3bl. The dyeing test according to 2. with 0.01 iodine-potassium iodide must at any rate be carried out in order to be able to distinguish between this size and polyacrlate or polyester size.

Polyvinyl acetate and polyvinyl alcohol sizes will become brown to purple brown with 0.01 N iodine-potassium iodide solution. After air-drying the sample sized with polyvinyl alcohol becomes colourless. The sample sized with poyvinyl acetate still has a brown colour. If both sizes are absent, the sample is dyed slightly yellow.

Characteristics:

Some polyacrylate sizes are applied as ammonium salts. The sizes show only a slight red dyeing with BEZACRYL RED BL LIQ.50% or Astrazon Red F3BL, thus indicating a small size layer. In case of a slight dyeing of the raw material after a treatment according to 1. a new sample is wet-out for 2sec. with a 0.1N caustic soda solution and tested according to 1. without intermediate rinsing. The sample treated in this way will show an intensive red dyeing in case of a size based on an ammonium salt, thus confirming the test indication.

Some polyvinyl acetate sizes are used as copolymers with the ammonium salt of the acrylic acid. These sizes do not become purple brown with iodine/potassium iodide solution. With BEZACRYL RED BL LIQ .50% or Astrazon Red F3BL there is only a slight colouration of these sizes. A sample as treated under 2. is treated with 0.01 N iodine solution in potassium iodide in order to identify these sizes clearly; before rinsing with water drop 0.1 N caustic soda on the sample. If the size described above is present a purple brown ring will develop.

The spotting test with mixed indicator 5 is another possibility to distinguish between different kinds of sizes.

Synthetic sizes have strong or weak acid groups and can be neutralized with strong or weak bases.

Strong acid polyester groups will give a blue spot with intensive red edge together with this indicator, i.e. there is a separation of the indicator mixture.

With acrylate sizes there will be no or only a very weak separation of the indicator mixtrue. This becomes obvious with a brown spot. Strongly acid reacting sizes will have an orange edge which is not defined clearly. in case of polyvinyl acetate sizes green spots will develop. With this indicator it is not possible to distinguish between polyvinyl acetate and polyvinyl alcohol.

In case of the presence of preparations (different ionic character)the identification with the mixed indicator may be impaired, because they have similar ph-values as sizes and impair the specific proof.

On pages 10 and 11 the colour reactions are indicated.

2.2
Size proof in aqueous extract

Additional substances insoluble in water such as paraffins, fats, waxes etc. will make the separation of sizes more difficult and will partially impair the proof reaction. Therefore it is recommended to carry out a treatment with petroleum ether even before carrying out an aqueous extraction. it is completely sufficient to immerse the fabric for 10 min . in these proofs too, it becomes obvious that sizes with the same or similar final groups very often react with the same substances.

By using different tragents and a systematic analysis the different sizes cam be distinguished from one another.

PVA, Starch, Starch ether
+lodine/potassium iodide
→PVA brown, purple brown
→Starch, starch ether blue

Distinction starch/starch ether PVA
Treatment with : 2,0 g/l BEISOL LZV at 50℃
or WITH 2,0 ㅎ/ㅣ BEISOL HTS AT 98℃
→starch is decomposed enzymatically after 10min
→starch ether after 15min
→PVA green to blue-green

Examination PVA
after enzymatic treatment extract with dilut. HCI+0.1N iodine/potassium iodide solution, + add a spatula poing of borax
→ blue dyeing of the borax : PVA positive

CMC(Carboxyl methyl cellulose)
The aqueous extract is mixed with 10% CuSO4-solution
→white deposit : CMC positive
→the white deposit will dissolve completely in acetic acid.
Add cationactive substances to the aqueous extract.
→white deposit: CMC positive

Polyacrylate
Add 10% HCI-solution to the aqueous extract.
→white deposit : polyacrylate positive
Add cationic substance to the aqueous extract.
→white deposit: polyacrylate positive
Add 10% cuso4-solution to the aqueous extract.
→white deposit which is only partly soluble in acetic acid: polyacrylate positive

Distinction of CMC polyacrylate by means of the MOLISCH reaction:
1 ml of approx. 10% solution of a-Naphthol in chloroform(must always be prepared fresh) is added to approx. 1ml of the aqueous extract. Then underlet cautiously with 1-2ml 98% h2so4, by adding it very slowly.
→Red-violet ring at the border of both liquids : CMC positive
Be careful : in case of cotton material do not boil the aqueous extract but immerse it cold, otherwise the proof will always be positive

Polyester and Polyvinyl acetate
Add a 10% HCI-solution to the aqueous extract:
→white deposit : polyester and polyvinyl acetate positive
add a cationic substance to the aqueous extract:
→white deposit : polyester and polyvinyl acetate positive
add a 10% cuso4-solution to the aqueous extract:
→white deposit : polyester and polyvinyl acetate positive

Polyvinyl acetate
Polyvinyl acetate can be proved as polyvinyl alcohol after saponification.

Reagents
- 0.01n iodine/potassium iodide solution
- 0.1 n iodine/potassium iodide solution
- BEISOL LZV or BEISOL HTS
- Borax
- 10% cuso4-solution
- 10% HCI-solution
- 10% solution of a-Naphthol in chloroform
- H2SO4 98%
- cationic auxiliary
- ammonia solution

Literature
1) Schlichtmann, Textilveredlung 15(1980)386-390
2) TEGEWA:Textil Praxis,36(1981)1331-1332,1349-1350
3) Denter,Dugal,Schollmeyer, Melliand 66(1985)142
4) spankers, scheer, lorenz, melliand 63(1982)254-261
5) Dugal, Heidemann, melliand 65(1984)216-217
6) brown, Olson, keegan, American dyestuff reporter(1967)703-707
7) schlichtmann, deutscher farberkalender, 1987
8) Agster, farberei-und textilchemische untersuchungen,10.auflage, springer verlag
9) Deuter, Schollmeyer, melliand 73(1992)267-274

3.
Desize of synthetic polymer sizes

In the following we have listed procedure proposals for desizing different synthetic polymer sizes.

Only two of our detergents are mentioned.

It goes without saying that all other detergents of our product assortment which have a good washing, dispersing or soil suspending property and a good wetting property can be used.

PES-size

Trade name : Eastman wd, Eastman mps, Gerol PHS

Chemical name : ester of the lsophtalic acid with Diolen

Structural formula:

Washing conditions : ph-value : 8,5'80-98℃

Remark: pH controlled by electrometer, over ph8.5 coagulation!
use Na4P2O7 discontinuously as alkali. sensitive to electrolytes!

Trade name : Bevaloid-, Vinarol-, Alkuzet-and inex-types

chemical name: partially saponified or modified polyvinyl acetate

structural formula:

washing conditions: PH-value:7-9;80-98℃

Remark: Dwelling times slightly longer than with synthetic sizes. use alkali, over ph10 coagulation of the PVA contained in the size.

Pure Acrylate size

trade name: size CB, Gerol ACR, size ca, synthoplex sl916

chemical name: polyacrylic acid as nh4+,Na+,Ca++ -salts or as pure polyacrylic acid

structural formula:

washing conditions: ph-value: for neutralized and partly neutralized acrylates ph9-10;80-98℃ for acrylic acid sizes pH12-13;80-98℃

Remark : NaOH or soda ash should be used as alkali. the first rinsing baths mustbei alkaline! control the ph-value!

Co-and block polymer

Trade name : Achalin PES

Chemical name : Polyvinyl acetat(polyvinyl alcohol-)-polyacrylic acid-copolymer

Struftural formula:

Washing conditions: ph-value:7.5;80-98℃

Remark : In case of longer dwelling times in hot liquors causes coagulation.
Higher liquor ratios in the first baths are necessary because it will split off more rapidly.