GB1578859A - Sublimable dye preparations and processes for their production - Google Patents

Description

(54) SUBLIMABLE DYE PREPARATIONS AND PROCESSES FOR THEIR PRODUCTION (71) We, YORKSHIRE CHEMICALS LIMITED, a British Company, of Black Bull Street, I.eeds, LS 10 lHP, West Yorkshire, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to finely divided dye preparations which are particularly suitable for printing ink preparation, and to a process for their manufacture.

It is well known that printing formulations containing binders and solvents and/or water together with a sublimable dye, can be applied to paper and subsequently the dye can be partially or wholly transferred on to textiles by heat treatment. This process is known as transfer printing. The dyes which are suitable for this application are usually insoluble or only very sparingly soluble in water and may be for example an azo, anthraquinone. diphenylamine, methine or naphthoquinone type. They must also be capable of transferring by sublimation at relatively low temperatures e.g.

1600 to 2209C. In some processes this transfer by sublimation may take place under pressures less than atmospheric. These dyes are often commercially available as disperse dves, in which large amounts of water soluble dispersing agents are associated with the dye itself in both powder and liquid forms of commercial dyes. For example, the dye:dispersant weight ratio might be 1:0.5 for liquid dye and 1:1 for a powder form of dve. When used in the preparation of transfer printing inks, high strengths, stability and suitable rheological properties are difficult to achieve with these products.

Thus dry filter cake, completely free of dispersing agent is often employed for the above application. whereby the ink maker grinds the dyestuff, in admixture with solvents and ink binders in. for examnle, a ball mill or stirred mill until the particular are below 10 lm. nreferahly below S Jm We have now discovered that it is possible to manufacture finely divided dyestuff preparations, which are eminently suitable for the above application by milling or grinding the dyestuff in a solvent or water in the presence of a small amount of an amphoteric grinding aid. The resulting liquid is preferably dried to produce a concentrated dry powder suitable for subsequent dispersion in either a solvent or aqueous based ink medium.In the complete absence of a suitable grinding aid, the mechanical comminution of dvestuffs in a liquid medium results in viscosity build up to an extent whereby comminution to the required particle size becomes aumost impossible.

The products of the current invention are finely divided dye preparations con taining only small amounts of an amphoteric grinding aid and are therefore free of the difficulties encountered with conventional disperse dyes in the above application.

In addition they allow the ink maker to reduce considerably the time taken to produce an ink with a particle size substantially below 10 um, using a ball mill or stirred mill or alternatively he may be able to cmploy equipment devoid of milling media such as high shear mixers, rotor/stator mixers, or high speed impellors and still produce an ink of acceptable particle size distribution.

According to the present invention, a process is provided in which at least one dyestuff which is suitable for transfer printing and which under the conditions of transfer will sublime at temperatures between 160 and 220"C. is milled or ground in a solvent or in water, at a concentration of 10 to 60% by weight, in the presence of 0.1 to 20% preferably 0.5 to 5 /O by weight on the weight of dry dyestuff used, of at least one amphoteric grinding aid selected from compounds of general formula::

and salts thereof, where Rl represents a saturated or unsaturated alkyl group of from two to twenty carbon atoms, R2 represents a straight or branched chain alkylene group from three to seven carbon atoms, X represents a methylene group or a secondary amino group, Rs represents a straight or branched chain alkylene of from one to seven carbon atoms, and Y represents a hydrogen atom, a carboxyl group, an alkyl group or an alkyl carboxy group such that the sum of the carbon atoms in groups Y and Rs is from one to seven, until the particle size of the dyestuff is below 10 /tom, preferably less than 5 pm.

The resulting dispersion may be employed directly for producing inks where the ink solvent and grinding solvent are compatible, or the dye dispersion may be processed further, for example by filtration and/or evaporation, to produce a dry powder.

The resulting dry dyestuff preparation contains from 0.1 to 20% by weight of grinding aid relative to the weight of dry dye used in its preparation.

If R' is the residue of a commercially available mixture of hydrocarbons in which the main components contain from two to twenty carbon atoms, it may also contain smaller amounts of lower and higher hydrocarbons.

The part of the molecule consisting of R'--XX-RRZ--NH- may for example be derived from a primary amine such as R1-CH2-R2-NH,, or from a diamine of the type R1-NH-R2-NH,.

In a further embodiment of the invention there is provided a dyestuff preparation (both liquid and powder dyestuff preparations are included) comprising at least one sublimable dye, as defined above, and 0.1 to 20% by weight based on the weight of dry dye, of at least one grinding aid selected from amphoteric amines of general formula I as defined above and their salts.

In the case of a liquid preparation the dry solids content of said liquid lies between 10% and 60%, preferably 20% and 60%, by weight.

Where more than one amphoteric grinding aid selected from amphoteric amines of general formula I and their salts is used, the total weight of such compounds should be from 0.1 to 20% by weight.

The sublimable dyestuff may be employed as wet filter-cake particularly for predominantly aqueous milling or dried, preferably by tray oven or vacuum drying prior to comminuting or grinding according to the process of the invention. Comminution may be conveniently carried out in, for example, a ball mill, bead mill or stirred mill.

As a variation on the process, the amphoteric milling aid may be added stepwise during the milling process or in the case of dyestuffs produced by coupling or another similar chemical process, the amine may be added to the suspension obtained by said coupling or other chemical process and removed by filtration together with the dyestuff. Further additions of the amine may be made during milling.

Suitable solvents are those in which the dyestuff has a solubility less than 1.0 gm/litre at 250C. and is preferably less than 0.1 gm/litre at 250C. Preferred suitable solvents are trichloroethylene, tetrachloroethylene, chloroform, toluene, xylenes and high boiling point paraffins such as white spirit and in particular, water.

When aqueous milling is employed, additional amounts of water miscible solvents may be added, for example, alcohols, or the solvent may be used to aid the dispersion/ dissolution of the amine prior to its addition to the milling composition. For example, the amphoteric grinding aids of Formula 1 may be soft or waxy type solids which are difficult to mix or blend with the dyestuff and water. Predispersion of the amphoteric amine in alcohol/water mixtures produces a low viscosity fluid which is more readily blended with the dye/water mixture.

Optional other additives during milling include the resin binders or dye carriers used in the preparation of transfer printing inks, and small quantities of the usual water-soluble dispersing agents for disperse dyes such as ionic or non-ionic surface active compounds e.g. lignin sulphonates and naphthalene sulphonic acid/formaldehyde condensates.

After milling, the dyestuff now in the form of a fine dispersion is preferably filtered to remove any large undispersed particles, milling medium etc. It may then be used directly to prepare inks or liquid dyestuff preparations which can be used subsequently for ink manufacture.

Alternatively the above dyestuff dispersion may be dried by conventional methods such as freeze drying, vacuum drying or spray drying etc. to produce a concentrated finely divided dry dye powder. By "dry" dye powder is meant a product of sufficiently low solvent or water content so that it can be ground into a free flowing powder.

After drying, the product may be blended in the dry state with compatible diluents such as carrier resins, surface active agents and inert compounds to provide a dry dyestuff preparation.

Thus the products of the current invention enable high strength inks to be produced with reduced milling/dispersion effort so that, for example, deep shades can be produced by various transfer printing techniques on polyester, or other hydrophobic fibre fabrics, using a variety of ink formulations, both aqueous and solvent based.

In a further embodiment of the invention, ink preparations are provided in which the dye preparations as described above have been incorporated.

The amphoteric amines of the present invention may be prepared, for example, by reacting an alkyl amine or diamine with a suitably ethylenically unsaturated carboxylic acid. Listed in the table below are examples of suitable grinding aids.

TABLE TABLE 1

Amine Acid Formula 1 CH, ample 2 Oleic propylene - Angelic Acid C,a-H37-NH-C3H,-NH-CH-CH-COOH di amine I CH3 ample 3 Laurylamine Crotonic Acid C,2H2sNH-CH-CH2-COOH COOH ample 4 Stearylamine Maleic Acid C,8H37-NH-CH-CH2-COOH The invention will be more clearly understood by reference to the following Examples, in which the grinding aids illustrated in Table 1 are utilised. The Examples are purely illustrative and all parts and percentages are by weight.

Example 1.

90 pts. of the filter cake of C.I. Disperse Red 59 containing 30 pts. dye, are dispersed in 60 pts. of water and 1.0 pt. of a 30% solution of Sample 1 in isopropyl alcohol is added. The suspension is passed through a bead mill containing 1.0 mm.

glass beads until the particle size is substantially below 5 um. The milled suspension is discharged from the bead mill free of glass beads and is spray dried to produce a finely divided dye preparation. A sample of unmilled filter-cake is oven dried and ground for comparison purposes.

Gravure inks are prepared by mixing 9 pts. of the two dye samples prepared as above, each with 43 pts. ethyl alcohol, 43 pts. isopropyl alcohol and 5 pts. of ethyl cellulose. The latter has an ethoxyl content of 47.0 to 49.0% and a 5.0 /O sclution in 80:20 toluene:ethyl alcohol has a viscosity of 25"C. of 18 to 24 cps.

The dye samples are dispersed using a high speed rotor-stator mixer to produce ink having a viscosity of 15 to 30 seconds on a No. 4 Ford Cup. Using the sample prepared according to the current invention, an ink of suitable particle size is obtained, whereas the sample of dried press-cake does not break down to give an acceptable dispersion. The results are confirmed by preparing paper prints and transfer printing the dye on to polyester fabric by heating for 30 seconds at 2100C., using conventional techniques. The well dispersed ink gives considerably better colour yield and definition.

A similar result is obtained by using xylene in place of both ethyl alcohol and isopropyl alcohol and otherwise carrying out the procedures as described above.

Example 2.

In the preparation of C.I. Disperse Yellow 3 (C.I.11855), 11 pts. of the coupling component para-cresol are slurried in an alkaline solution to which 0.5 pts.

of Sample 2 are added. The coupling solution is cooled and added slowly to 14.5 pts.

diazotised para-aminoacetanilide dispersed in 500 pts. of water, when a bright yellow precipitate is obtained. When the reaction is complete, the mixture is warmed, filtered hot, and dried to produce a dyestuff containing 1 to 2% of the sample preparation No. 2. 10 pts. of dry dyestuff together with 55 pts. of trichloroethylene are ground in a ball mill with 350 pts. of ceramic milling media (2 mm. diameter) until the particles are substantially below 5 Lum. The resulting suspension is separated from the milling media and vacuum dried to produce a finely divided dye preparation.

A finely dispersed ink is produced according to the procedure described in Example 1, and a similarly good result is obtained when the ink is evaluated by the transfer printing process described Example 3.

133 pts. of filter-cake containing 40 pts. of dry C.I. Disperse Yellow 54 (C.I.47020) are charged together with 67 pts. of water and 1.0 parts of Sample No. 3 into a bottle containing 700 pts. of 1 to 2.0 mm. ceramic milling media and agitated on a paint shaker until the particle size of the dye is substantially below 5 glum. The dispersion is now separated from the milling media and filtered to produce a filter-cake of 30 /O solids content. 100 pts. of Glascol 86T, a 40% active acrylic copolymer. ("Glascol" is a registered trade mark of Allied Colloids Ltd.), are diluted with 16 pts. of water and 4 pts. of monoethanolamine. 120 pts.

of the wet filter-cake prepared above are added to the acrylic polymer and mixture re-shaken with the same milling media until the dyestuff is completely dispersed.

After separation from the milling media, the dispersion is adjusted to pH 8.5 to produce a water-based ink with good stability which is suitable for flexographic printing processes.

Alternatively, the dye dispersion obtained initially is dried to produce a finely divided dye preparation and the ink prepared by dispersing 36 parts of dry dyestuff in 100 parts of acrylic emulsion. 100 parts of water and 4 parts of ethanolamine.

Using dried press-cake of C.I. Disperse Yellow 54, ink of similar quality may be produced, but dispersion of the dye in the ink medium takes considerably longer to achieve.

WHAT WE CLAIM IS: 1. A process for making a dyestuff preparation which comprises milling or grinding, in a solvent or water, at least one dyestuff which is suitable for transfer printing and which under the conditions of transfer will sublime at temperatures between 160 and 220"C. at a concentration of 10 to 60% by weight, in the presence of 0.1 to 20% by weight based on the weight of dry dyestuff used, of amphoteric grinding aid comprising at least one compound selected from amphoteric amines of general formula:

and salts thereof, where R' represents a saturated or unsaturated alkyl group of from two to twenty carbon atoms, R2 represents a straight or branched chain alkylene group from three to seven carbon atoms,

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (16)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   The dye samples are dispersed using a high speed rotor-stator mixer to produce ink having a viscosity of 15 to 30 seconds on a No. 4 Ford Cup. Using the sample prepared according to the current invention, an ink of suitable particle size is obtained, whereas the sample of dried press-cake does not break down to give an acceptable dispersion. The results are confirmed by preparing paper prints and transfer printing the dye on to polyester fabric by heating for 30 seconds at 2100C., using conventional techniques. The well dispersed ink gives considerably better colour yield and definition.

   A similar result is obtained by using xylene in place of both ethyl alcohol and isopropyl alcohol and otherwise carrying out the procedures as described above.

   Example 2.

   In the preparation of C.I. Disperse Yellow 3 (C.I.11855), 11 pts. of the coupling component para-cresol are slurried in an alkaline solution to which 0.5 pts.

   of Sample 2 are added. The coupling solution is cooled and added slowly to 14.5 pts.

   diazotised para-aminoacetanilide dispersed in 500 pts. of water, when a bright yellow precipitate is obtained. When the reaction is complete, the mixture is warmed, filtered hot, and dried to produce a dyestuff containing 1 to 2% of the sample preparation No. 2. 10 pts. of dry dyestuff together with 55 pts. of trichloroethylene are ground in a ball mill with 350 pts. of ceramic milling media (2 mm. diameter) until the particles are substantially below 5 Lum. The resulting suspension is separated from the milling media and vacuum dried to produce a finely divided dye preparation.

   A finely dispersed ink is produced according to the procedure described in Example 1, and a similarly good result is obtained when the ink is evaluated by the transfer printing process described Example 3.

   133 pts. of filter-cake containing 40 pts. of dry C.I. Disperse Yellow 54 (C.I.47020) are charged together with 67 pts. of water and 1.0 parts of Sample No. 3 into a bottle containing 700 pts. of 1 to 2.0 mm. ceramic milling media and agitated on a paint shaker until the particle size of the dye is substantially below 5 glum. The dispersion is now separated from the milling media and filtered to produce a filter-cake of 30 /O solids content. 100 pts. of Glascol 86T, a 40% active acrylic copolymer. ("Glascol" is a registered trade mark of Allied Colloids Ltd.), are diluted with 16 pts. of water and 4 pts. of monoethanolamine. 120 pts.

   of the wet filter-cake prepared above are added to the acrylic polymer and mixture re-shaken with the same milling media until the dyestuff is completely dispersed.

   After separation from the milling media, the dispersion is adjusted to pH 8.5 to produce a water-based ink with good stability which is suitable for flexographic printing processes.

   Alternatively, the dye dispersion obtained initially is dried to produce a finely divided dye preparation and the ink prepared by dispersing 36 parts of dry dyestuff in 100 parts of acrylic emulsion. 100 parts of water and 4 parts of ethanolamine.

   Using dried press-cake of C.I. Disperse Yellow 54, ink of similar quality may be produced, but dispersion of the dye in the ink medium takes considerably longer to achieve.

   WHAT WE CLAIM IS: 1. A process for making a dyestuff preparation which comprises milling or grinding, in a solvent or water, at least one dyestuff which is suitable for transfer printing and which under the conditions of transfer will sublime at temperatures between 160 and 220"C. at a concentration of 10 to 60% by weight, in the presence of 0.1 to 20% by weight based on the weight of dry dyestuff used, of amphoteric grinding aid comprising at least one compound selected from amphoteric amines of general formula:

   and salts thereof, where R' represents a saturated or unsaturated alkyl group of from two to twenty carbon atoms, R2 represents a straight or branched chain alkylene group from three to seven carbon atoms,

   X represents a methylene group or a secondary amino group, Rs represents a straight or branched chain alkylene of from one to seven carbon atoms, and Y represents a hydrogen atom, a carboxyl group, an alkyl group or an alkyl carboxy group such that the sum of the carbon atoms in groups Y and R' is from one to seven, until the particle size of dyestuff is below 10 um.
2. 2. A process as claimed in Claim 1, in which 0.5 to 5% by weight of the amphoteric grinding aid is present.
3. 3. A process as claimed in Claim 1 Of 2, in which the grinding or milling is carried out until the particle size of the dyestuff is less than 5 im.
4. 4. A process as claimed in any one of the preceding claims in which the sublimable dyestuff is employed as wet filter-cake.
5. 5. A process as claimed in any one of the previous claims in which comminution is carried out in a ball mill, bead mill or stirred mill.
6. 6. A process as claimed in any one of the previous claims in which trichloroethylene tetrahydroethylene, chloroform, toluene, a xylene or a high boiling point paraffin is used as solvent.
7. 7. A process as claimed in any one of the preceding claims in which the dyestuff dispersion produced during milling is subsequently dried to produce a concentrated finely divided dry dyestuff preparation.
8. 8. A process as claimed in Claim 7, in which after drying, the product is blended in the dry state with compatible diluents.
9. 9. A process for making a dyestuff preparation substantially as hereinbefore described in any one of the foregoing Examples.
10. 10. A dyestuff preparation comprising at least one sublimable dye, as defined in Claim 1, and 0.1 to 20% by weight, based on the weight of dry dye, of grinding aid comprising at least one compound selected from amphoteric amines of general formula I as defined in Claim 1 and their salts.
11. 11. A dyestuff preparation as claimed in Claim 10, which is in liquid form and the dry solids content of said liquid lies between 10% and 60% by weight.
12. 12. A dyestuff preparation as claimed in Claim 11, in which the dry solids content of said liquid lies between 20% and 60% by weight.
13. 13. A dyestuff preparation as claimed in any one of Claims 10 to 12, comprising from 0.5 to 5% by weight of grinding aid.
14. 14. A dyestuff preparation as claimed in Claim 10, substantially as hereinbefore described in any one of the foregoing Examples.
15. 15. An ink preparation in which a dye preparation as claimed in any one of Claims 10 to 14 has been incorporated.
16. 16. An ink preparation substantially as hereinbefore described in any one of the foregoing Examples.