CN1088236A - dry leuco sulfur dye granules - Google Patents

Abstract

The production method of water-soluble dry leuco sulfur dye (L), wherein, Put the sulfur dye (S) in an aqueous medium at a temperature > 60°C with An effective amount of reducing carbonyl compound (A) is reacted and dried, and the reaction is In the presence of alkali metal hydroxide (B) and may be present Sulfate and/or alkali metal bisulfite (C) OK. Wherein said drying finishes with spray drying, and drying time＜4 minute. Thus, sulfide-free, stable and water-soluble leuco sulfur can be obtained chemical dye (L). It is especially suitable for sulphide-free dyeing, specifically It is suitable for dyeing polyamide fibrous objects, especially wool.

Description

In British Patent Application No. 9210931.3 (publication date: November 25, 1992, No. 2255981, hereinafter referred to as GB-A-2255981, corresponding to Chinese Patent Application No. 92-103925.5, the contents of which are incorporated herein by reference) discloses the following method of producing dry water-soluble leuco sulfur dyes: in the presence of alkali metal hydroxides and optionally alkali metal sulfites and/or alkali metal bisulfites, the sulfur dyes Reacting with an effective amount of a reducing carbonyl compound at >60°C and drying in a medium, wherein the reacting and drying may be at least partially simultaneous.

It has now been found that if the reaction mixture is spray dried, especially with hot air, drying, preferably reacting and drying, can be accomplished in a very short time, less than 4 minutes, especially within seconds .

The present invention relates to said spray-drying method, to the corresponding dried product and its use in dyeing.

The present invention therefore provides a process for the production of a water-soluble dry leuco sulfur dye (L), wherein the sulfur dye (S) is mixed with an effective amount of a reducing carbonyl compound (A) in an aqueous medium at a temperature >60°C reacting and drying, the reaction is carried out in the presence of alkali metal hydroxide (B) and may exist alkali metal sulfite and/or alkali metal bisulfite (C); wherein said drying is accomplished by spray drying, Drying time <4 minutes. If the reaction and drying are carried out separately, the components (S), (A), (B) and (C) and their corresponding amounts and reaction conditions are as defined in the above GB-A2255981. (S) may be any commercially available sulfur dye, or may also be an oxidized and/or acidified sulfur reaction product, preferably in wet form, preferably washed filter cake. (A) Specifically, a monomeric or oligomeric ketose or aldose or hydroxyacetone, preferably an aldopentose monomer or an aldohexose monomer. (B) and (C) which can be used are in particular the corresponding lithium, sodium or potassium compounds, among which the sodium compounds are preferred. The amount of (A) is preferably in the range of 1-40% by weight of (L), more preferably 5-15%. The weight ratio of (A)/(S) is preferably in the range of 5/100-40/100, more preferably 10/100-20/100. The (B)/(S) weight ratio is preferably such that an excess of (B) is present in the final product, preferably 0.5-20% by weight of (L), more preferably 3-10%. The amount of (C) is advantageously within the range of 1-40% by weight of (L), preferably 2-24%, and most preferably 5-10%. The weight ratio of (C)/(S) is preferably in the range of 5/100-40/100, more preferably in the range of 10/100-20/100. The weight ratio of (A)/(C) is preferably in the range of 1/5-5/1, most preferably 2/1-1/2. The water content in the mixture to be dried, i.e. the total water content of the reaction mixture at the beginning of drying is at least advisable with the following conditions: the mixture is easy to spray, and the water phase represents the continuous phase; the water content≤95% by weight is more favorable, as mentioned in GB-A2255981 As stated in, 10-90% by weight is preferred, and 20-80% by weight is the best.

Drying can be accomplished by any conventional spray-drying system known per se, for example by spray-freeze drying (if the reaction has been completed) or preferably by hot gas (G).

Suitable gases (G) are those which are substantially inert to (L) under the spray-drying conditions, ie which do not cause substantial chemical modification of the product (L) during spray-drying. Gases (G) that come into consideration are, for example, nitrogen, superheated steam or/and air. For the production of leuco sulfur dyes (L) readily oxidizable by hot air, the gas is preferably an inert gas substantially free of oxygen, most preferably nitrogen or a mixture of air and nitrogen. For leuco sulfur dyes (L) that are more resistant to air oxidation, such as leuco sulfur dyes (L) that have a higher threshold of incipient hot air oxidation and are not destroyed by short-term hot air treatment in a spray dryer [e.g. For dyes of Color Index Leuco Sulfur Black 1 and 2 (L)] hot air can be used as hot gas (G). Suitable hot air is generally preferred for industrial reactions; its suitability for spray drying of a given dye (S) and dye (L) respectively can be determined by a few preliminary tests. Most preferred (G) is nitrogen.

Drying with hot gas (G) is of particular advantage at least partially concurrent with the reduction reaction; preferably the reduction reaction is carried out concurrently with the drying so that the moisture content of the reaction mixture corresponds to that of the mixture to be dried.

Drying can be carried out within the temperature range indicated in GB-A2255981, or even at higher temperatures, depending on the drying system in the spray dryer. The inlet temperature of the hot gas (G) entering the dryer (i.e. the temperature at which (G) is sent into the spray dryer) can be within the range of conventional operating temperatures known per se, specifically >70°C, ≥ 105°C is more favorable, >150°C is the best, the upper limit of (G) inlet temperature is mainly determined by the performance and size of the dryer, ≤300°C is more favorable, ≤280°C is the best, for (G) into the spray The inlet temperature of the dryer, the preferred range is 150-300°C, especially 165-300°C, the preferred temperature when (G) is sent into the dryer is the temperature at which drying starts, that is, it is greater than the boiling temperature of water, specifically It is in the range of 105-300°C, preferably in the range of 150-280°C, especially ≥200°C.

The gas (G) is fed into the dryer at a suitable superatmospheric pressure, e.g. in the range 2-50, preferably 2.5-25, especially 3-12 kg/cm.

Preferably, the mixture to be dried is fed into the spray dryer at an elevated temperature, preferably below the boiling temperature of the mixture, preferably in the range of 50-100°C, preferably 70-98°C, and It is best in the range of 85-98°C. Drying in a spray dryer is suitably carried out under such conditions and parameters that the outlet temperature of the gas (G) (i.e. the temperature at which (G) leaves the spray dryer) is between 60-180°C for hot air and/or nitrogen It is more favorable in the range of 100-150°C; or for superheated steam, it is more favorable in the range of 105-250°C, preferably 150-240°C. The dryer is suitably operated in the following way: During the fall of the sprayed particles in the dryer, the temperature of the reaction mixture is greatly increased, and the dried particles are 10-60°C higher than the temperature of the mixture to be dried being fed into the dryer. , It is best to leave the dryer with an outlet temperature 15-40°C higher.

The spray dryer can be, for example, a dryer for conventional spray drying, in particular a dryer that sprays the liquid composition to be spray-dried into a dry product by atomization, specifically nozzle atomization, rotary atomization or acoustic atomization. device. The hot gas (G) can be introduced cocurrently or countercurrently with the spray particles. According to a preferred method of operation, spray drying is accomplished by injection atomization. Another preferred method is to use rotary atomization, especially vertical rotary atomization (eg also with a steam turbine).

The nozzles or other feed means (e.g. cups, pans, turbines) used to spray the composition into the dryer are preferably selected to be compatible with the incoming composition. Specifically, if the composition to be sprayed is a dispersion containing (S), the type, shape and size of the spraying device should be selected to suit the dispersion to be sprayed. According to a preferred feature of the invention, the composition to be sprayed, in particular the composition containing the sulfur dye (S) which has not been reduced with (A) is preferably treated in the absence of (A) and (C) Preheat to the right temperature to make it more runny or liquid. The suitable temperature is ≤100°C, specifically in the range of 50-98°C, preferably 60-95°C. It is advantageous to proceed as follows: in this step, (S) has not yet reacted to a large extent to (L) but has just been solubilized with (B). (A) and optionally (C) are preferably mixed with a preheated aqueous mixture of (S) and (B) [where (S) is preferably solubilized with (B)] and immediately fed into the spray dryer .

The drying time, specifically, the reaction and drying time <2 minutes is more favorable, preferably within 1-60 seconds, and most preferably within 2-30 seconds. The feed rate of the composition to be dried, specifically to be reacted and dried, should be determined according to other parameters and the moisture content of the composition, and can be, for example, in the range of 100-100001/hour, preferably 200-50001/hour. hours, for example about 4m ³ /hour, which also depends on the capacity of the dryer.

If according to the preferred mode, the reaction in the hot gas (G) and the spray-drying are carried out at least partly simultaneously, it is even better if the unreacted reactant mixture is sprayed into the drier and the reduction reaction is simultaneously carried out completely in the drier; During the drying process of the falling spray droplets, the reaction of (S) with (A) in the presence of (B) and possibly (C) takes place in each spray particle, and within seconds Dried granules of water-soluble leuco sulfur dyes (L). In particular, if, in a preferred manner, the composition contains unreacted sulfur dyes (S), during drying of the granules with hot gas (G), the sulfur dyes (S) are gradually converted into The reaction product (L), which is at least partially soluble in the water present in the granules; however during spray drying the water is evaporated, therefore, when during drying the outside (L) of the granules is enriched , in the interior of the particles, the water still present promotes the further reaction of the (S) still present, and at the end of the drying of the particles, the reaction of (S) to (L) in each particle is practically complete.

The reaction proceeds surprisingly completely and the product obtained is a particulate water soluble dry leuco sulfur dye (L), preferably in a pourable particle size.

As dry product, in particular dry product (L), is meant a solid leuco sulfur dye as obtainable by the drying process, in particular a solid leuco sulfur dye with a water content as follows: by weight of product , with a water content of ≤5%, preferably ≤2%, and preferably ≤0.5%.

Depending on the system and configuration of the spray dryer and the operating parameters used, the dried particles obtained can be of corresponding shape, size and consistency. Examples of forms are: rigid porous granules or/and hollow granules or/and crushed granules or/and flattened granules or flakes or other forms. Depending on the configuration and operating conditions of the spray dryer, the dried product can be obtained in various particle sizes, specifically in the range of 1 μm-2 mm. For example in preferred nebulizer systems the particle size is predominantly in the range 1-20 [mu]m. If the particle size of the dry granules is particularly fine, especially fine powder with a particle size of ≤5 μm or even 10 μm, it has the advantage of being able to accumulate into larger particle size agglomerates, preferably within the range of 0.01-10mm, preferably 0.01 -4mm, especially in the range of 0.05-4mm is better; this is conducive to obtaining a substantially dust-free product, for example preferably in the form of flakes or granules with a particle size in the range of 0.2-2mm.

If necessary, a suitable accumulation system can be directly fixed or connected to the outlet of the dryer so that the fine powder can be sent directly into the accumulation device. The agglomeration device may be any conventional suitable system such as a mixer, granulator, pelletizer or any other system suitable to provide particles of the desired size. To agglomerate the fine powder into larger particles, suitable, preferably non-aqueous, water-soluble additives can be used, especially additives commonly known for dust control, such as glycerol, _C2 - _C4 alkylene di Alcohols, oligo-(C _2-4 -alkylene)-glycol ethers and their C _1-4 alkyl monoethers, preferably mono- or dipropylene glycol-methyl ether. The amount of these anti-dust additives can be very small, specifically, the amount is in the range of 0.5-8 parts by weight per 100 parts by weight (L), preferably 1-4 parts by weight. The selection of the optimal amount may vary according to the size and shape of the powder particles and the desired particle size and consistency of the aggregated product and also according to the system used.

In terms of subsequent accumulation, especially with anti-dust additives, the dry powder at the outlet of the spray dryer is preferably cooled to <100°C, for example in the range of 50-100°C or even lower, to be particularly suitable for Corresponding equipment and additives.

The obtained dry products (L) are practically free of inorganic sulphides and are stable against air oxidation; they are also very soluble in water, even at temperatures ≤ 40 °C, for example in the temperature range 5-25 °C Soluble in water, they are therefore very suitable for direct use in dyeing, even for low-temperature dyeing methods, and for the preparation of stock solutions.

The leuco sulfur dye (L) obtained according to the present invention is suitable for dyeing any dyeable object dyeable with sulfur dye, especially cellulose dyed object, with the leuco form of sulfur dye; in addition, because it does not contain sulfide and has Good solubility and therefore also suitable for dyeing polyamide substrates, especially fibrous substrates, such as synthetic polyamides, wool and leather (eg also leather with wool), wool being particularly preferred. Dyeing can be accomplished by conventional methods known per se, in particular impregnation with (L)-containing impregnation compositions [it is advantageous to heat-treat the impregnated dyed object (for example with superheated steam)] and from the leuco stage to sulfur dyes The decisive oxidation of the dyeing stage is accomplished, or by the exhaustion (exhaustion) and the decisive oxidation of the dyeing from the leuco stage to the sulfur dye stage by an aqueous solution containing (L) (addition of electrolytes such as sodium sulfate is more advantageous). . The aqueous dyeing solution preferably also contains antioxidant additives, such as reducing sugars, hydroxyacetone, thiourea dioxide, sodium bisulfite or/and formaldehyde sulfoxylate. The dyeing of polyamide to be dyed can be carried out in aqueous medium under the following conditions: weakly acidic to weakly alkaline, for example, the pH value is in the range of 6-8.5, preferably 6.5-8.5, and the suitable temperature is less than 100°C Favorable, better in the range of 40-90°C, 70-85°C is the best; after washing and rinsing, the leuco form can be applied to the dyed object by using an oxidizing agent, preferably H ₂ O ₂ Oxidized to form sulfur dyes, the oxidation is carried out under the following conditions: weakly acidic (for example with acetic acid), the temperature is preferably in the range of 30-60 ° C, especially 35-50 ° C, for a short time, such as 10 seconds to 10 minutes, preferably 30 seconds to 4 minutes, according to the needs of the corresponding dyed objects and dyeing. The leuco sulfur dyes (L) can be used in any concentration suitable for the respective dyed material and desired color intensity. The resulting aqueous solution of leuco sulfur dye (L) may have a concentration of, for example, 50-100 g/l, or even higher.

It is possible to obtain dyeings with enhanced shade and outstanding fastnesses, especially light and wet fastnesses.

Since the dry product (L) is substantially free of inorganic sulphides, there is no interfering, organ-perceivable evolution of _H2S during the dyeing process. The exhausted mother liquors can be recycled for further dyeing or/and in the remaining solution (eg from washing and rinsing), the remaining (L) can be obtained by methods known per se, e.g. Metal ions are either precipitated and separated by desolubilization with mineral acids.

The stock solution is stable for several hours without interfering oxide film formation. The dyeing operation can be carried out in the dyeing machine substantially free of any disturbing oxidative deposits.

The following examples illustrate the present invention, wherein the percentages are by weight and the temperatures are in degrees Celsius.

Example 1

200g of 2,4-dinitrochlorobenzene was reacted with 169g of 50% sodium hydroxide aqueous solution at 100°C for 2 hours. The resulting product was added to a mixture of sodium sulphide (200g) in water (200g) and 127g of sulfur, the mixture was heated to 116-120°C and refluxed at this temperature for 10-15 hours. The mixture was then diluted with 200 g of water and the solution was bubbled with air until the dye was precipitated. The resulting mixture is then filtered and washed with water to obtain a black dye cake with a water content of 40-60%. The obtained filter cake was mixed with 120 g of a 50% aqueous sodium hydroxide solution, the mixture was heated to 90° C. and 28 g of glucose and 28 g of sodium bisulfite were added thereto. The resulting mixture was immediately injected into a hot air spray dryer at a rate of 445 liters/hour through an injection sprayer nozzle; air was introduced at a superatmospheric pressure of 4-7 Kg/ ^cm2 and a temperature of 165°C. The outlet air is 118°C, and the drying is complete after 5-15 seconds. The temperature of the dried product at the outlet was 105-110°C. The product leaving the dryer is a fine powder with a particle size of 5-10 μm.

Example 2

Example 1 was repeated with 100-fold quantities (particularly composition and feed ratios) under industrial-scale operating conditions with an inlet air temperature of 220°C and an outlet air temperature of 120°C.

Example 3

Example 2 was repeated, but with a different hot gas (G), nitrogen instead of hot air.

Example 4

Example 3 was repeated except that the nitrogen inlet temperature was 280°C and the nitrogen outlet temperature was 105°C.

Example 5

Example 3 was repeated except that the nitrogen inlet temperature was 300°C and the nitrogen outlet temperature was 110°C.

The reaction mixture used in the above examples was the non-dried mixture of Example 8 of GB-A2255981.

Other non-dried mixtures exemplified in each of Examples 1-7, 9-14 and 8 (two)-11 (four) of GB-A 2255981 can be dried in the same manner as in Examples 1-5 above.

Example 6

The powder obtained in Examples 1-5 was mixed with 2% dipropylene glycol-methyl ether in a mixer to obtain particle agglomerates, the particle size of which was in the range of 0.2-2mm.

All products obtained are readily soluble in water and practically free of inorganic sulfides.

Application Example A

5 g of the dry product obtained according to Example 1 were dissolved in 90 g of water within 5 minutes, and 2.5 g of glucose and 2 g of 50% aqueous caustic soda were added thereto. A piece of cotton fabric was soaked with the solution until the liquid absorption rate reached 100%, and then washed under steam at 102°C for 1 minute. The fabric was then oxidized by treating it with an aqueous solution containing 5 g/l _H₂O₂ (30%) and 5 g/l acetic acid (80%) at ₄₀ °C for 1 minute, then washed and dried to give a deep black dyeing.

Application Example B

0.7 g of the black dry product of Example 1 was dissolved in 200 g of water containing 4 g of sodium sulfate and 0.5 g of thiourea dioxide. A piece of wool fabric weighing 10 g was dyed in this solution for 1 hour at 75-80°C and pH 6.5-8.5 (adjusted with acetic acid if necessary). The treated woolen fabric was then washed and oxidized in a manner similar to that described in Application Example A, and finally the dyed woolen fabric was washed and dried to obtain a deep black woolen fabric with outstanding wet and light fastness properties.

Similar to the dried product of Example 1, each dried product of the above Examples 2, 3, 4, 5 or 6, or use the drying method of the above Example 3 or 4 to combine the embodiments 1-7, 9 of GB-A 2255981 - 14 and 8 (two) - 11 (four) The corresponding products obtained after drying the undried mixture listed in each are used in the above application examples A and B to obtain dyeing with corresponding color and luster and fastness.

Claims (12)

1. A method for producing a water-soluble dry leuco sulfur dye (L), wherein the sulfur dye (S) is reacted with an effective amount of a reducing carbonyl compound (A) in an aqueous medium at a temperature > 60° C. Drying, the reaction is carried out in the presence of alkali metal hydroxide (B) and the presence of alkali metal sulfite and/or alkali metal bisulfite (C); Wherein said drying is accomplished by spray drying, and the drying time is less than 4 minutes. 2. A process according to claim 1, wherein the spray drying is carried out with hot gas (G). 3. A process according to claim 2, wherein the hot gas (G) is hot air or hot nitrogen. 4. A method according to any one of claims 1 to 3, wherein the aqueous mixture is sprayed into the drier by atomization. 5. A process according to any one of claims 2 to 4, wherein the gas (G) has an inlet temperature > 150°C. 6. A process according to any one of claims 1 to 5, wherein drying and reducing are carried out at least partly simultaneously. 7. A process according to any one of claims 1 to 6, wherein reduction and drying are carried out in a time of <2 minutes. 8. A process according to any one of claims 1 to 7, wherein the dry granules obtained are agglomerated into granule agglomerates having a particle size in the range 0.01-4 mm. 9. Use of a dry leuco sulfur dye (L) obtainable according to any one of claims 1 to 8. 10. A method for dyeing a dyeable object dyeable with a sulfur dye, which comprises treating a leuco form of a sulfur dye and then oxidizing the leuco form into a sulfur dye form; wherein the leuco sulfur dye according to claim 9 (L) is used as a leuco sulfur dye. 11. A method according to claim 10, which is used for dyeing polyamide fibrous objects. 12. A method according to claim 11 for the dyeing of wool.