GB2230533A

GB2230533A - Production of dyestuff granules and pellets

Info

Publication number: GB2230533A
Application number: GB9006704A
Authority: GB
Inventors: Juergen Haverbier
Original assignee: Bayer AG
Current assignee: Bayer AG
Priority date: 1989-03-30
Filing date: 1990-03-26
Publication date: 1990-10-24
Anticipated expiration: 2010-03-26
Also published as: CH678729A5; GB9006704D0; GB2230533B; FR2645164A1; DE3910275C1

Description

Process for the production of dyestuff granules The present invention

relates to the production of dye is stuff granules in cylindrical form which, in addition to the dyestuff# optionally contain dispersing agents, extenders, dedusting agents, emulsifiers, granulating liquid and the like.

The cyclindrical pellets preferably have a diameter of 1 to 3 mm and a length of 2 to 15 mm. Particularly preferred pellets have a diameter of about 2 mm and a length of 5 to 10 mm, In factories where dyestuff& are used, for example in the textile industry, dyestuffs of the most diverse kinds are required. The dyestuffs are predominantly used in the form of powder&, This does however have various disadvantages The greatest disadvantage is the in some 30 cases extensive development of duct from the powder# added to which it is very difficult to disperse and dissolve powder in water because it spreads poorly and tends to form lumps# In addition# powder cannot be used Le A 26 729 for metering units and has a high packing volume because of its relatively low bulk density.

If the dyestuff is processed into granules a number of advantages resultThe granules$ for examples cylindrical pellets, can be easily strewn into the water present in the vessel employed and dissolve or become dispersed within a short period of time without lump formation or adherence to the vessel walls The pellets are ideally suitable for metering units since they have good flow properties and ideal metering properties, do not stick is to each other and do not adhere to silo walls. The bulk density is 1.5 to 2 times greater than that of powder, thus resulting in a considerable saving in packaging.

Further advantages over the powder form and other granulating processes are:

- low investment costs small amount of space required for the extrusion unit high production capacity minimal maintenance costs rapid product changeover low manpower requirements low energy costs no variation in product quality - no lump formation Le A 26 729 1 1 The disadvantage of the known cylindrical pellets is their low abrasion resistance which results, inter alia, in undesired dust formation.

It has now been found that these disadvantages can be avoided if dyestuff powders having a specific degree of residual moisture are extrusiongranulated.

The invention therefore relates to a process for the production of dyestuff granules in cylindrical form, characterised in that dyestuff powders having a water content of 5-10, preferably 7-12 % by weight, are subjected to extrusion granulation.

The dyestuffs contained in the granules according to the claims can belong to the most diverse classes, such as, for example, azo dyestuffs, anthraquinone dyestuffs, triphenylmethane dyestuffs, sulphur dyestuffs, pigment dyestuffs, methine dyestuffs and triarylmethane dyestuffs.

Water-soluble dyestuffs, for the textile, paper and leather industry are preferred, Reactive dyestuffs and non-reactive acid dyestuffs are particularly preferred.

Suitable dispersing agents which can be contained in the dyestuff preparations are: surfactants from the group comprising condensed aromatic sulphonic acids, such as, for example, naphthalenesulphonic acid/formaldehyde condensates, and lignin sulphonates etc. (cf. for example DE-A 2,317,175).

Le A 26 729 1 - 4 Suitable extenders are preferably inorganic salts such as, for example, sodium, magnesium and potassium sulphate, sodium and potass.ium chloride, monosodium and disodium phosphate and borax.

Dedusting agents which may be mentioned are: dibutyl phthalate, dimethyl phthalate, fatty alcohols, poly ethers and mineral oils.

Suitable emulsifiers are alkoxylated fatty alcohols and amines.

is The preferred granulating liquid is water.

The cylindrical granules have, for example, the following composition:

Acid dyestuff types 65.0 - 75.0 % of dyestuff 0.0 - 10.0 % of extenders 0.4 - 0.8 % of dedusting agents 0.1 - 0.2 % of emulsifier and 10.0 - 15.0 % of water 2. Reactive dyestuff types 30.0 - 85.0 % of dyestuff 0,0 - 600 % of dispersing agents 0,0 - 600 % of extenders 0.4 - 1.2 % of dedusting agents 0,1 - 0.3 % of emulsifiers and 10.0 - 15.0 % of water, Le A 26 729 the sum of the constituents in.each case being 100% by weight.

The starting materials for the production of the pellet are dyestuffs in powder form which form a slight to small degree of dust. The powders are obtained, for example, by spray-drying the aqueous filter cakes to which auxiliaries have optionally been added.

Flat die presses manufactured by Amadeus KAHL GmbH & Co., D-2057 Reinbek bei Hamburg, have proven to be suitable machines for carrying out the process.

Le A 26 729 6 Description of the process

The KAHL press operates acdording to the process of extrusion agglomeration with the aid of a flat die and rollers as the pressing tools. The dyestuff powder is metered vertically from above into the press chamber and forms a layer of material on the die. The rollers roll over and compact this layers The compressive force increases constantly as the rollers roll in the direction of the press channel until it has become so high that the product is pressed by the rotating rollers through the nozzle grid = die and is shaped to form endless strands of uniform density. The adjustable cutting device below the die cuts the shaped strands to the desired length. It is not generally necessary to subsequently dry the pellets.

The process can be used both continuously and discon tinuously.

It will be understood that the invention has been described above purely by way of example, and that various modifications of detail can be made within the ambit of the invention.

:1 1 Le A 26 729

Claims

Patent Claims

14 Process for producingdyestuff granules in cylindrical form, characterised in that dyestuff powders having a water content of 5-15% by weight are subjected to extrusion granulation.
2 Process according to Claim 1, characterised in that the cylindrical pellets have a diameter of 1 to
3 mm and a length of 2 to 15 mm, 3. Process according to Claim 1, characterised in that the extrusion granulation is carried out using a flat die.
4, Process for producing dyestuff pellets in cylindrical form# characterised in that dyestuff powders having a water content of 5-15% by weight are subjected to extrusion agglomeration and the shaped strands are cut to the desired length without subsequent drying.
5. Any one of the processes according to claim 1, substantially as hereinbefore specifically described.

Le A 26 729 Published 1990at7Ine Patent 0MU.StAtCHOUBC.68?1 High Rolborn. London WC1R 4TP. PurLher copies be obtdt=m The PatentOtfice