WO2014032134A1

WO2014032134A1 - Concentrated sugar preparation as reducing agent for sulfur dyes

Info

Publication number: WO2014032134A1
Application number: PCT/BR2012/000327
Authority: WO
Inventors: Helio Haruo USHIJIMA; Silvana MARQUEZ
Original assignee: Cargill Inc
Current assignee: Cargill Inc
Priority date: 2012-08-30
Filing date: 2012-08-30
Publication date: 2014-03-06
Anticipated expiration: 2015-02-28
Also published as: AR092395A1; BR112015004395A2

Description

CONCENTRATED SUGAR PREPARATION AS REDUCING AGENT FOR SULFUR

DYES

FIELD OF THE INVENTION

The present invention generally concerns a concentrated sugar preparation comprising (a) raffinate derived from the citric acid recovery industry and (b) a sugar-containing solution useful as reduction agent for sulfur dyes.

BACKGROUND OF THE INVENTION

Dyes are natural or synthetic substances that appear to be colored because they absorb certain wavelengths of light more than others. Sulfur dyes are the most commonly dyes used for textiles (mainly cotton) as dark colors such as black, brows, or dark blue.

The basic technology referring to the oxidation- reduction of dyes to provide color in textile materials is old and wide (for instance US 5,586,992, Basf AG, 1996).

Once sulfur dyes are water insoluble, reduction and oxidation reactions are used during the dyeing. Reduction compounds are used to break such dyes into small particles to improve affinity to the fabric and oxidation compounds are subsequently used to return insolubility, fixing the dye and revealing the color.

Commonly sulfur dyes are absorbed by fabrics from a bath containing sodium sulfide or sodium hydrosulfite during the reduction step (for instance GB 2,201,165, Sandoz AG, 1988) .

However, such reduction compounds in the waste stream generate bad odor, toxicity and high chemical oxygen demand (COD) . Recent advances in dyeing technologies seek the substitution of toxic sulfide reducing agents.

In this sense, attempts to introduce glucose as an ecological substitute for traditional reduction agents have failed.

The state of the art teaches that although glucose has a high ecological advantage, its use turns out to be disadvantageous as the equilibrium of the redox potential is reached comparatively slowly and unsatisfactory for complete reduction (Marken: Dyes and Pigments, 2006 cited in WO2009051569 ; Vuorema et al: Anthraquinone catalysis in the glucose-driven reduction of indigo to leuco-indigo, Phys . Chem. Chem. Phys . , 2009, 11, 1816-1824; Vuorerna et al: Electrochemical and sonoelectrochemical monitoring of indigo reduction by glucose, Dyes and Pigments, 76 (2), pp. 542-549, 2008; Magdalena Nunez: New developments in electrochemistry research, Science, 2005) .

A number of patent references also corroborate that the use of glucose reduction agents for sulfur dyes is not efficient, for instance DE 4,115,452 (Basf AG, 1992), US 5,244,549 (Verein Zur Forderung der Forschung und Entwicklung in der Textilwirtschaft , 1993), EP 699,797 (Sandoz Ltd, 1996), US 6,093,221 (Sudzucker

Aktiengesellschaft , 2000) .

Thus, there remains a need in the art for an ecological and efficient reduction agent for sulfur dyes in order to replace traditional sulfide reducing agents.

DESCRIPTION OF THE INVENTION

In order to overcome the inconveniences mentioned above, specially concerning pollution and toxicological effects, a specific concentrated sugar preparation was developed to be used as reduction agent for sulfur dyes in general, which is able to increase the redox potential, but mainly maintain it after the addition of electrolytes necessary for the conclusion of the dyeing.

Such a reduction agent according to the present invention comprises (a) raffinate and (b) sugar-containing solution .

According to the present invention the raffinate (a) is an aqueous solution effluent (for instance syrup or liquor) from fermentation processes (residuary or not) . Raffinate (a) is an aqueous solution comprising at least citric acid, inorganic matter (such as minerals), proteic matter and sugar matter.

Typically, sugar matter includes carbohydrate selected from fructose, dextrose, maltose and/or polyol selected from arabitol, erythritol, or mixtures thereof. The inorganic matter is measured by analyzing ashes and typically includes nitrogen, phosphorus, potassium, calcium, magnesium, sulphur, iron, manganese, copper, zinc, boron, sodium or mixtures thereof.

In a particular embodiment, raffinate (a) is a by-product derived from the citric acid recovery process, for instance as disclosed in the patent US 4,994,609, assigned to Cargill Inc. (1991), incorporated herein as reference. The raffinate (a) ingredients ratio depends on the performance of the recovery industry. One advantage of this invention resides in the fact that a by-product without commercial application is used as raw material for the manufacture of a commercial product, also avoiding the cost with waste disposal treatment.

The sugar-containing solution (b) may be obtained from several sources, for instance corn, sugar cane, cassava, potato, wheat, rice, etc. In a particular embodiment such a solution may be syrup, i.e. a viscous liquid with sugar content. Such a component also includes enzymatic or acid conversion syrup, independently from the conversion grade.

Sugar, according to the present invention, is selected from carbohydrates or saccharides in general, including monosaccharides, disaccharides, oligosaccharides, polysaccharides; or mixture thereof. For instance, the solution (b) comprises monosaccharide such as glucose (dextrose), fructose (levulose) , galactose, xylose or ribose; disaccharides such as sucrose, maltose or lactose; oligosaccharides such as raffinose or stachyose; polysaccharides such as or starch, amylose, amylopectin, cellulose, chitin; hydrolysates (for instance inverted sugar), derivatives or mixtures thereof.

According to the present invention the sugar- containing solution (b) may be a viscous concentrated solution of sugar, in water or other liquids (for instance alcohols) . Such a solution may also include other ingredients such as coloring agents, flavors or thickening agents .

In a particular embodiment component (b) contains about 40% equivalent dextrose in relation to about 80% total solids. For instance, such an ingredient is commercialized as Glucogill 40/82 by the Cargill group in Brazil .

The concentrated sugar preparation comprises:

(a) from about 10 to about 90%, preferably about 50% raffinate from a citric acid recovery process, and

(b) from about 10 to about 90%, preferably about 50% glucose syrup.

As a second aspect, the present invention also concerns a process for manufacturing a reducing agent comprising the following steps of:

(i) Evaporation of raffinate component (a) up to about 65% solids;

(ii) mixing sugar-containing solution (b) until complete homogenization; (iii) controlling the viscosity by addition of sugar-containing solution (b) if necessary, considering a minimum of about 500 and a maximum of about 2, 500 cP (at 25°C) .

The resulting reducing additive according to the present invention presents the following characteristics:

(a) % Brix (sugar parameter) from about 70 to about 75.

(b) Viscosity: a minimum of about 500 and a maximum of about 2, 500 cP (at 25°C) .

The % Brix is analyzed by a refractometer . The viscosity is measured by cooling the sample at 25 °C and 20 rpm in a Brookfield viscometer DV I.

Due to the characteristics of the additive according to the present invention, especially with respect to controlled concentrations of sugar, as well as physical characteristics (viscosity) , it is possible to obtain an improved ingredient able to act as efficient reduction agent for sulfur dyes while it is environment friendly.

By "efficient reduction agent" according to the present application it is understood an agent that is able to increase the redox potential and maintain it after the addition of electrolytes necessary to the conclusion of the dyeing process, i.e. comparable to the traditional sulfide reducing agents.

It was found that the application of sugars alone (for instance glucose) as reduction agent for sulfur dye is not possible, due to its poor redox performance. Contrary to what one would expect in view of the prior art, the raffinate (a) is able to regulate the sugar-containing solution redox activity. Moreover, there is created a use of a waste derived from the citric acid industry, providing a low-cost and environment friendly reducing product, while avoids the use of pollutant sulfide reduction agents.

The concentrated sugar additive according to the present invention may also comprise other ingredients well known in the art, such as fragrances, surfactants, biocides, pH adjusters, thickeners, etc.

The present invention also concerns the use of the preparation as described above as reduction agent for sulfur dyes and a method for reducing sulfur dyes during the dyeing process that comprises applying a reducing amount of a preparation as described above.

The following examples are provided for illustrative purposes only, and are not intended as a limitation to the scope of the present invention, other than what is described in the attached claims.

EXAMPLES

OBTAINING OF RAFFINATE

A raffinate sample was obtained from the citric acid recovery process disclosed in the patent US 4,994,609, assigned to Cargill Inc. (1991) .

Such an ingredient was evaluated in order to identify organic and mineral contents.

One test was carried out to verify the mineral ingredients contained in the raffinate (a) . Therefore, ashes without organic elements (i.e. water, citric acid, raw protein and sugar not converted) were evaluated and the following composition was identified:

Table 1 - Raffinate characteristics: inorganic elements

(<1.0%)

Ingredient Amount

Nitrogen 0.58%

Phosphorus 0.12%

Potassium 35.0 ppm

Calcium 148.0 ppm

Magnesium 25.0 ppm

Sulphur 0.25 ppm

le include: Table 2- Raffinate characteristics: organic elements

The analyzed sample also contains solids (15%) and trace ingredients (<100ppm) . C/N ratio = 19 and pH = 3.

PREPARATION OF THE REDUCTING AGENT PREPARATION

A sample of the reducing agent was prepared by:

(a) evaporation of a raffinate stream according to a process disclosed in the patent US 4,994,609 up to 65% solids ;

(b) mixing 5 kg of the raffinate obtained in the step (a) with 5 kg of glucose syrup, commercialized as Glucogill 40/82, until complete homogenization.

The viscosity and sugar content of the resulting mixture was then analyzed: (a) % Brix (sugar parameter) from about 70 to about 75.

(b) Viscosity: below 1, 500 cP (25°C) .

REDOX PERFORMANCE - SUGAR SOLUTIONS

The redox potential is a fundamental factor to keep the sulfur dye in the soluble state during the dyeing process. Therefore, the smaller the difference between the initial and final redox, better the efficiency of the reduction agent.

For the tests below:

- Initial redox: value measured immediately after the addition of antioxidant.

- Final redox: value measured after the addition of salt (electrolyte) .

The reducing agents were evaluated in view of their capability for increasing and maintaining redox value after addition of electrolyte.

Test parameters:

The moisture content of each product was discounted to calculate the amount to be applied.

The working conditions were reproduced;

alkaline pH (60 ml/1 NaOH at 38°Be) .

20 g/L of glucose anti-oxidant .

25 g/L of NaCl.

redox potential mV at 50°C with Pt.

Table 3 - Results

Sample initial final Final Δ Average redox redox redox Equivalent mV mV mV Dextrose

Mono Dextrose 680 530 150 99, 5

Glucose syrup 590 300 290 38-40

Maltose Syrup 600 380 220 45-55 Glucose syrup 680 510 170 75-80 75DE

Glucose syrup 690 600 90 60-64 63DE

As tle initial and final redox values are important to maintain the sulfur dye in the soluble state during the dyeing process, one can observe that glucose syrup 63DE had the best performance.

REDOX PERFORMANCE - COMPARATIVE TESTS

Each sample below was diluted to 10% solids. The measurement of redox potential was carried out using an ORP (oxydation reduction potential) electrode.

Comparing the results above one can observe the best performances were obtained by two samples according to the present invention. Sample 1 with controlled viscosity presents a Δ redox more than 2 times better than traditional glucose.

The information contained in the foregoing, as well as in the examples, allows a person skilled in the art to perform alternative embodiments not expressly described, but which perform the functions taught herein with the results revealed herein. Such equivalent embodiments are encompassed by the scope of the invention and are therefore covered by the claims presented further on.

Claims

1. REDUCING AGENT FOR SULFUR DYES comprising a mixture of (a) raffinate and (b) a sugar-containing solution .

2. REDUCING AGENT, according to claim 1, wherein raffinate (a) is a by-product derived from a citric acid recovery process.

3. REDUCING AGENT, according to one of claims 1 or 2, wherein raffinate (a) is an aqueous solution comprising at least citric acid, inorganic matter, proteic matter and sugar matter.

4. REDUCING AGENT, according to claim 3, wherein sugar matter comprises carbohydrate selected from fructose, dextrose, maltose and/or polyol selected from arabitol, erythritol, or mixtures thereof.

5. REDUCING AGENT, according to claim 3, wherein inorganic matter includes nitrogen, phosphorus, potassium, calcium, magnesium, sulphur, iron, manganese, copper, zinc, boron, sodium, or mixtures thereof.

6. REDUCING AGENT, according to one of claims 1 to 5, comprising from about 10 to about 90% raffinate.

7. REDUCING AGENT, according to one of claims 1 to 6, comprising about 50% raffinate.

8. REDUCING AGENT, according to claim 1, wherein the sugar-containing solution (b) comprises monosaccharide, disaccharide, oligosaccharide, polysaccharide; or mixture thereof .

9. REDUCING AGENT, according to one of claims 1 or 8, wherein the sugar-containing solution (b) comprises glucose, fructose, galactose, xylose, ribose, sucrose, maltose, lactose, raffinose, stachyose, starch, amylose, amylopectin, cellulose, chitin, hydrolysates, derivatives or mixtures thereof.

10. REDUCING AGENT, according to one of claims 1, 8 or 9, wherein the sugar-containing solution (b) is Glucogill 40/82.

11. REDUCING AGENT, according to one of claims 1 or 8 to 10, comprising from about 10 to about 90% sugar- containing solution (b) .

12. REDUCING AGENT, according to one of claims 1 or 8 to 11, comprising about 50% sugar-containing solution (b) .

13. REDUCING AGENT, according to one of claims 1 or 8 to 12, wherein the sugar-containing solution (b) contains about 40% equivalent dextrose in relation to about 80% total solids.

14. REDUCING AGENT, according to one of claims 1 or 8 to 13, wherein the sugar-containing solution (b) is derived from corn.

15. REDUCING AGENT, according to one of claims 1 to 14 presenting the following characteristics:

(a) % Brix from about 70 to about 75;

(b) viscosity of a minimum of about 500 and a maximum of about 2, 500 cP (at 25°C) .

16. PROCESS FOR MANUFACTURING THE REDUCING AGENT according to one of claims 1 to 15 comprising the steps of:

(a) evaporation of raffinate component (a) up to about 65% solids;

(b) mixing sugar-containing solution (b) until complete homogenization

(c) controlling the viscosity by addition of glucose syrup component (b) if necessary, considering a minimum of about 500 and a maximum of about 2,500 cP.

17. USE OF THE AGENT according to one of claims 1 to 15 for reducing sulfur dyes during textile dyeing process .

18. METHOD FOR REDUCING SULFUR DYES comprising applying a reducing amount of an agent according to one of claims 1 to 15 during textile dyeing process.

19. METHOD FOR DYEING TEXTILES comprising applying a reducing amount of an agent according to one of claims 1 to 14 during textile dyeing process.