Bleaching Composition

Abstract

This disclosure relates to bleaching laundry compositions comprising a chlorine bleach, an optical brightener, preferably of the sulfonated triazole class, and a reducing agent such as inorganic sulfites, organic sulfinates, water-soluble phosphites, and inorganic alkaline materials combined with hydrogen peroxide. The presence of the reducing agent enables the composition to enhance brightening of the fabric being cleaned without adversely affecting the bleaching thereof to any appreciable extent. The optional addition of a detergent or surface active agent, also beneficially affects the brightener intensity.

Parent Case Text

This application is a continuation of Serial No. 679,506, filed October 31, 1967, now abandoned.

Description

The present invention relates to a bleaching composition containing a chlorinated bleach, and a stabilized optical brightener system.

The use of optical brighteners in chlorine bleach compositions to effect brightening on clothes is common practice. However, the problem of incompatability of brighteners of desirable hue with the chlorine bleach compound is well recognized in the art. This difficulty has been overcome in the past by the use of specific classes of optical brighteners. However, it has been found that chlorine bleach compositions, particularly chloroisocyanurate bleach is non-compatible with most brighteners of desirable hue and of reasonable cost, the neutral blue fluorescence being preferable.

Another problem encountered with the optical brighteners is its instability towards the chlorine bleach in the wash solution, whereby it is destroyed by the chlorine prior to its adherence to the fabric. This difficulty has been solved in the past by the use of ultra-marine blue pigment which attempts to mask any yellowing due to repeated bleaching or the inherent color of the fluorescent brightener. Another solution to this problem involves the compounding of a solid core of bleach with an outer contiguous coating which contains the optical brightener, detergent and other additives; whereby the outer coating dissolves first and permits the attachment of the brightener to the fabric before it can be destroyed by the chlorine bleach. The destroyed action of the bleach resulting from the aforementioned solid composition has only limited utility in view of the fact that the fabric must be present in the wash solution prior to the dissolution of the bleach therein. There must be a fabric onto which the brightener can adhere, otherwise the effectiveness of the brightener is destroyed by the chlorine bleach. Thus, it is apparent that the many solutions to the problem of a stabilized optical brightener coexisting with a chlorine bleach have been partial and incomplete.

It has now been found that the addition of a reducing agent to a chlorine bleach composition containing an optical brightener effects improved whiteness of fabric. Presumably the reducing agent provides a more easily oxidizable substance than the brightener for the initial action taken by the chlorine bleach, thereby protecting the brighteners until it is absorbed onto the fabric. Moreover, in addition to the protection afforded to the brightener it is conceivable that dye and fabric damage as evidenced by localized bleaching and weakness of fiber would also be diminished by the presence of a reducing agent.

Accordingly, the present novel bleaching compositions containing optical brightener and reducing agent have the advantage of being suitable in a laundering medium even though the introduction of textile materials be delayed for a reasonable time. It permits the addition of the fabric to the wash solution which is the conventional method of home laundering, without appreciable, if any, loss in the whitening by bleach and with appreciable increased brightening effect by the brightener. The small, if any, loss in whitening by the bleach due to the presence of reducing agent is more than compensated by the appreciable increase in the efficiency of the brightener.

More specifically, the instant invention relates to a bleaching composition comprising a chlorine bleach, an optical brightener, and a reducing agent readily oxidizable in aqueous medium.

Any chloride bleaching agent, organic or inorganic (e.g. calcium hypochlorite and the like) capable of liberating chlorine ions in an aqueous medium is suitable for use in the instant novel compositions. Particularly efficient are dry, granular, organic bleaching compounds such as trichloroisocyanuric acid (TCCA), dichloroisocyanuric acid (DCCA) and the sodium and potassium salts of dichloroisocyanuric acid (NaDCC and KDCC). The weight of chlorine bleaching agent to be used in a dry composition will be dependent upon the available chlorine content of the bleach ingredient selected. Compositions of this invention can be formulated to provide aqueous wash solutions with a wide range of available chlorine content, and mixtures of these. Preferably, the compositions to be used in aqueous solution will deliver between 40 to 400 ppm of available chlorine.

The optical brightener which is an essential ingredient in a wash solution, are fluorescent materials that are substantive to cloth and provide thereby a desirable hue, preferably blue. They are commonly used in heavy duty laundry products. Unfortunately, not all fluorescent brighteners are compatible for use with a chlorine bleaching agent. Consequently, this difficulty is one of the major reasons for the use of a mixture of optical whitening agents in laundry products. In this respect the 2-stilbymonotriazole, benzimidazole, and dibenzothiophene dioxide type brighteners are characterized by a significant degree of resistance to chlorine bleach. On the other hand, the less expensive and exceptionally strong cotton brighteners having the trizinyl stilbene structure are generally classified as being ineffective in the presence of a chlorine bleach.

The optical brightener is an essential ingredient in the instant composition since it enhances the brightness of textiles and counteracts the yellowing of fabric due to repeated bleaching. Although any optical brightener characterized above as being possessed of a significant degree of resistance to chlorine bleach can be utilized herein, the sulfonated triazoles are preferred. An example of a 2-stilbemonotriazole type brightener is sodium 2-sulfo-4-(2-naphtho-1,2 triazole) stilbene of the following formula: ##SPC1##

Also, the presence of a small amount of sodium sulfite in a wash solution containing certain triazinyl type brightener and chlorine bleach will effect a significant improvement in the deposition of brightener onto fabric. For this class of brightener, the disodium salt of 4,4'-bis (4-anilino-6-morpholino-S-triazin-2-yl-amino) 2,2' stilbenedisulfonate is preferred. It is represented by the following formula: ##SPC2##

A small but significant amount of brightener is necessary to effect the brightness onto the fabric, about 0.05 to 1.0 percent of the total composition. Preferably the brightener-bleach composition will provide a wash solution containing about 3-10 ppm of the 2-stilbyltriazole brightener.

The chloroisocyanurates are usually mixed with dry, water soluble salts preferably alkaline salts as carrier agents to provide bulk and alkalinity to the bleaching compound when dissolved in water. Sodium tripolyphosphate and sodium carbonate are commonly used to provide desirable alkalinity and sodium sulfate or sodium chloride are often used as filler. Such compositions in the presence of certain brighteners as for example the monosulfostilbene naphthomonotriazole, sodium 2-sulfo-4(2-naphtho-1,2 triazole) stilbene, are able to whiten clothes by reason of the bleaching agent and also the optical whitener. However, the magnitude of the fluorescent intensity on fabric is dependent upon the conditions of use and the formulation of the product. For example, in a hand soaking operation or mechanical washing machine, the brightener effectiveness is related to the time of bleach and brightener contact prior to the addition of fabric and to whether an organic surfactant detergent, preferable of the anionic sulfonate or sulfate class, is present in the solution in a sizable amount. Minimum time elapse prior to addition of textile materials to the bleach solution and the presence of a substantial amount of an organic detergent in the solution provides for better overall whitening of the textiles being cleaned. To omit the organic detergent from a wash solution containing otherwise the same concentration of brightener, bleach and inorganic builders will invariably result in less brightener substantivity on fabric being washed. Moreover, the effect of sodium tripolyphosphate concentration toward brightener substantivity on fabric being washed in a bleach-brightener solution not containing anionic detergent indicates that brightener ability is not dependent, at least entirely, on pH conditions. Instead, the behavior of bleach-brightener systems suggests the possibility that an initially fast reacting and strong oxidizing material or medium associated with initial hydrolysis of the chloroisocyanurate tends to destroy the small amount of brightener present before it adheres to the fabric unless a more easily oxidizable substance, presumably the alkylbenzene sulfonate, is present. Indeed, as shown in the examples of this invention, by the use of a small amount of reducing agent in a brightener-bleach solution containing inorganic salts, the same or better fluorescent intensity on fabric can be obtained as would be achieved by use of a substantial amount of a detergent composition containing organic surfactant.

In addition to sodium tripolyphosphate, sodium carbonate, sodium sulfate and sodium chloride, other suitable inorganic salts may serve to adjust pH and also to act as carrier or dispersion medium for the bleaching agent or brightener, such as: potassium carbonate, sodium and potassium silicate, borax, trisodium phosphate, tetra sodium pyrophosphate, disodium hydrogen phosphate, pentapotassium tripolyphosphate, and nitrilotriacetic acid (including alkaline metal salts).

The proportion of inorganic build salts which is used may vary widely. Most desirably, sodium tripolyphosphate and sodium sulfate comprise the bulk of the inorganic salt content. Formulated compositions without or with minor amounts of organic surfactant should preferably deliver under use condition between 150-450 ppm of sodium tripolyphosphate to the wash solution.

The reducing agent which is another essential ingredient of the instant invention may be any water soluble salt that is easily oxidizable such as sodium and potassium sulfite, sodium and potassium hypophosphite, sodium thiosulfate, sodium dodecylbenzenesulfinate, sodium toluenesulfinate, sodium benzenesulfinate, sodium perborate and sodium percarbonate. In solution, sodium percarbonate and sodium perborate release oxygen in the presence of chloroisocyanurate and the resulting effervescence aids in the disintegration or dissolution of the product.

Depending on conditions and desirable degree of fluorescence relative to bleaching the quantity of reducing agent used may vary considerably. An effective amount of reducing agent is related to the bleaching composition used, particularly to the selected chlorine compound used therein. The purpose of the reducing agent may be to enhance brightener intensity on textiles with appreciable loss in bleaching of the fabric or its purpose may be to obtain optimum fluorescent intensity while obtaining a lower though satisfactory level of bleaching by the chlorine compound. Accordingly, the effectiveness of the brightener-bleach composition to brighten textiles will be related to the moles quantities of reducing agent and chlorine compound that could theoretically react completely in solution. In general the amount of reducing agent will vary from about 30 percent to about 80 percent and preferably from about 5 percent to about 25 percent of the stoichiometric requirement for completing reaction with the bleach compound. To exemplify the specific system such as sodium sulfite-KDCC, it will be noted that the stoichiometric quantities are 2 moles of sodium sulfite to 1 mole of KDCC. Preferred system for use in this invention would employ on a molar basis 0.06 to 0.40 moles of sodium sulfite per mole of KDCC.

The bleaching compositions of the instant invention are dry, water-soluble powders, which may be packaged in bulk in assorted containers or in individual, premeasured water-soluble packets. The water-soluble polyvinyl alcohol film is particularly useful as packet material since it has long shelf life and is resistant to gases, oil and grease.

The compositions suitably may contain additional constituents such as water-soluble organic surface active agents which are stable in the presence of the chlorine-liberating compounds. Such surface active agents may be anionic detergent salts having alkyl group of eight to 22 carbon atoms such as the water-soluble olefin sulfonates, paraffin sulfonates and the higher fatty acid alkali metal soaps, e.g. sodium myristate and sodium palmitate; water-soluble sulfated and sulfonated anionic alkali metal and alkaline earth metal detergent salts containing a hydrophobic higher alkyl moiety (typically containing from eight to 22 carbon atoms) such as alkyl mono- or poly-nuclear aryl sulfonates having from 10 to 16 carbon atoms in the alkyl group (e.g. sodium dodecylbenzenesulfonate, magnesium tridecylbenzene sulfonate, lithium or potassium pentapropylene benzene sulfonate); alkali metal salts of higher alkyl naphthalene sulfonic acids, sulfated higher fatty acid monoglycerides such as the sodium salt of the sulfated monoglyceride of coconut oil fatty acids and the potassium salt of the sulfated monoglyceride of tallow fatty acids; alkali metal salts of sulfated fatty alcohols containing from 10 to 18 carbon atoms (e.g. sodium lauryl sulfate and sodium stearyl sulfate); alkali metal salts of higher fatty acid esters of low molecular weight alkylol sulfonic acids, e.g. fatty acid esters of sodium salt of isethionic acid; the fatty ethanolamide sulfates; the fatty acid amides of amino alkyl sulfonic acids, e.g. lauric acid amide of taurine; as well as numerous other anionic organic surface active agents such as sodium toluene-sulfonate, sodium xylene-sulfonate, sodium napthalene sulfonate; and mixtures thereof. In general these organic surface active agents are employed in the form of their alkali metal salts or alkaline earth metal salts as these salts possess the requisite stability, solubility, and low cost essential to practical utility. It has been found that a long chain alkylbenzene-sulfonate is particularly effective in the enhancement of brightener intensity. The amount of organic surface active agent utilizable herein may vary from 0 to 35 percent of the composition.

Minor amounts of optional ingredients which do not interfere with the bleaching and brightening action of the composition may be included such as coloring materials, perfumes, corrosion inhibitors, binders, suds suppressors, etc.

The following examples are illustrative of the invention and it will be understood that the invention is not limited thereto.

EXAMPLES I AND II

Ingredients Examples __________________________________________________________________________ I II __________________________________________________________________________ alkylbenzenesulfonate detergent* - 1.5 g. Potassium dichloroisocyanurate 0.4 g. 0.4 g. Sodium tripolyphosphate (NaTPP) 0.4 g. 0.4 g. Sodium sulfate 1.0 g. 1.0 g. Sodium sulfite (reducing agent) 75 mg. 75 mg. Monosulfostilbene naphthomonotriazole brightener I 3.0 mg. 3.0 mg. pH (completion of Wash) 7.4 8.5 *Contains: 21% Sodium tridecylbenzenesulfonate, 35% sodium tripolyphosphate, 27% sodium sulfate, 7% sodium silicate, 1% Borax, 9% moisture.

Each of the dry powder compositions given in Examples I and II was dissolved in a liter of water and pre-agitated in a tergotometer at 120.degree.F for two minutes. Then, to each test solution was added 6 cotton, 3 nylon, and 3 dacron non-soiled swatches having the dimensions of 3 .times. 6 inches. These test fabrics were subjected to a 10-minute wash cycle in the brightener-bleach solution and then rinsed and dried at 140.degree.F for 2 hours in a forced draft oven. After a period of about 18 hours at room temperature, fluorescent intensities (F.I.) of the test fabrics treated in each of the test solutions were obtained by means of a fluorimeter. The results clearly showed that the fluorescent intensity of the above treated fabrics was far greater than that of fabrics washed with bleach-brightener compositions containing no reducing agent.

EXAMPLE III

Ingredients Amounts __________________________________________________________________________ Sodium tridecylbenzenesulfonate detergent 2.0 g. Potassium dichloroisocyanurate 0.4 g. Sodium tripolyphosphate 0.6 g. Sodium sulfate 1.0 g Monosulfostilbene naphthomonotriazole, brightener I 3.0 mg. Sodium sulfite (reducing agent) 50.0 mg.

This dry powder composition was dissolved in a liter of water and pre-agitated in a tergotometer at 120.degree. for 5 minutes, conditions which are far more severe for chlorine and brightener stability than ordinarily experienced under actual use. Test fabrics, either 12 sulfur dyed swatches (3 .times. 6 inches) or 12 white cotton swatches (3 .times. 6 inches) were introduced into the receptacle containing the brightener-detergent bleach solution and subjected to a 10 minute wash cycle (pH 8.6). The fabrics were rinsed, dried and tested for brightness and bleaching improvement. The fluorescent intensity measurements with fluorimeter of the above treated fabrics were far greater than that of fabrics washed with bleach-brightener compositions containing the same ingredients except that the reducing agent was omitted. Reflectance measurements taken with Gardner Color Difference Meter on sulfur dyed swatches showed that the small amount of sulfite used to improve the brightener intensity has little, if any, adverse effect on bleaching.

EXAMPLE IV

The sodium sulfite content of Example III was doubled and the composition then evaluated as before. Fluorescence intensity of the white cotton fabric was superior to those treated in Example III. The reflectance value for the sulfur dyed fabric was slightly lower than obtained in Example III but the bleached fabric had the same fluorescent intensity as in Example III.

EXAMPLE V

The composition given in Example I was dissolved in a liter of water and pre-agitated in a tergotometer at 120.degree. for either 0-, 2-, or 5 minutes prior to the addition of 12 white cotton swatches (3 .times. 6 inches). After a 10 minute wash period, the fabrics were rinsed, dried and compared against fabrics subjected to the same treatment with the exception that sodium sulfite was omitted from the composition. Average fluorimeter readings for test fabrics treated with a solution of composition containing sulfite were 86, 88, 90 for 0, 2 and 5 minute pre-wash times respectively versus only 33, 25 and 12 readings on fluorimeter for fabrics treated with solution not containing sulfite. At the end of the wash cycle with 5 minute pre-wash pH of sulfite solution was 7.5 and available chlorine loss amounted to 18 percent. The pH of solution without sulfite was 7.9 and available chlorine loss amounted to 8 percent.

EXAMPLE VI

The disodium salt of (dimorpholino s-triazin-2-ylamino) stilbenedisulfonic acid (Brightener II) was used in place of the triazole brightener in Example V. Fabric treated with this brightener-bleach sodium sulfite solution exhibited superior brightness both visually and when measured on the fluorimeter.

EXAMPLES VII, VIII AND IX

Ingredients VII VIII IX __________________________________________________________________________ anhydrous sodium sulfate 0.997g. 0.997g. 0.997g. Brightener (the triazole of Example I) 0.003g. 0.003g. 0.003g. Potassium dichloroisocyanurate 0.4g. 0.4g. 0.4g. Sodium thiosulfate 0.1g. 0.08g. 0.15g. Sodium tripolyphosphate 0.6g. 0.6g. 0.6g.

The use of sodium thiosulfate as the reducing agent in the bleach-brightener composition yielded similarly superior brightness in fabrics treated therewith as in the previous examples.

EXAMPLE X

Ingredients Compositions __________________________________________________________________________ Potassium dichloroisocyanurate 0.4 g. Sodium tripolyphosphate 0.4 g. Sodium sulfate 1.0 g. Sodium hypophosphite monohydrate 50.0 mg. Monosulfostilbene naphthomonotriazole brightener I 3.0 mg.

In a tergotometer at 120.degree.F, a solution of this composition was agitated for 5 minutes prior to addition of test fabrics. The 6 white cotton, 3 coffee/tea stained and 3 sulfur dye stained swatches were washed in the solution for 10 minutes and then evaluated for brightening and bleaching as described in previous examples. By visual observation and by measurements taken on a Gardner Color Difference Meter, the coffee/tea stained and sulfur dyed fabrics were strongly bleached to the same extent as were fabrics washed under the same conditions but no hypophosphite. However, the fluorescent intensity on the white fabric treated with the solution containing hypophosphite was considerably higher, measured on a fluorimeter than white fabric treated with a solution of this composition that did not contain sodium hypophosphite. The pronounced difference was discernible to the eye in the presence of ultraviolet light. This demonstrates inter alia, that in a mixed load of stained and unstained goods, equivalent bleaching is achieved on the stained goods (i.e. vis-a-vis treatment with no reducing agent) along with superior brightening of the unstained goods.

On completion of the wash cycle, the solution had a pH of about 7.6 and available chlorine loss of about 19 percent, which was similar to the result obtained by a solution minus the hypophosphite reducing agent. ##SPC3##

The presence of organic sulfinates as the reducing agent is a brightener-bleach composition improves brightener intensity on fabric, similarly to the compositions of Examples I thru X. Moreover, the effectiveness of the organic sulfinates for cleaning and brightening efficiency is particularly noticeable when the solution contains from 0.2 to 0.5 g. of organic sulfinate and the same type and quantity of brightener, bleach and phosphate as given in Example III but the sulfonate detergent is not present.

EXAMPLES XXIV - XXX

The organic sulfinates of the previous examples were replaced by 0.025, 0.05, 0.075, 0.1, 0.2, 0.3, 0.4 g. of sodium perborate (H.sub.2 O.sub.2 content, 21 percent) with similarly superior brightness results, the fluorescent intensity increasing progressively as the concentration of the perborate increased.

EXAMPLES XXXI - XXXVII

The perborates of the previous examples were replaced by 0.025, 0.050, 0.075, 0.10, 0.20, 0.30 and 0.40 g. of sodium percarbonate (H.sub.2 O.sub.2 content 25 percent). The treated fabrics were whiter and brighter as clearly evidenced by the fluorescent intensities measured on a fluorimeter which progressively increased with an increase in the concentration of the percarborate.

EXAMPLE XXXVIII

The following composition is prepared:

KDCC 0.145 g. TCCA 0.036 g. NaTPP 0.400 g. K.sub.2 CO.sub.3 0.050 g. Na.sub.2 SO.sub.3 0.050 g. Na.sub.2 SO.sub.4 0.050 g. Brightener I 0.003 g.

The results are comparable to Example I.

The compositions of all the aforementioned examples may be packaged in individual substantially water-soluble packets. These dry, powdered compositions may also be bulk-packaged in suitable containers such as cardboard boxes, plastic containers, etc. The powder may also be pressed into tablet form and suitably packaged. The reducing agent can be incorporated into detergent composition for separate addition to any brightener-bleach solution.

Although the present invention has been described with reference to particular embodiments and examples, it will be apparent to those skilled in the art that variations and modifications of this invention can be made and that equivalents can be substituted therefor without departing from the principles and true spirit of the invention.

Claims

I claim:

1. A powdered bleaching composition consisting essentially of a chlorine bleaching agent capable of liberating chlorine ions in an aqueous medium, about 0.05 to 1.0 percent of a chlorine resistant optical brightener of the sulfonated triazole class, and a water soluble reducing salt readily oxidizable in an aqueous medium by said chlorine bleaching agent, the ratio of said reducing agent to said bleaching agent ranging from 0.03:1 to 0.8:1 on a Stoichiometric basis, said reducing salt being more readily oxidizable by said chlorine bleaching agent than said brightener.

2. A composition in accordance with claim 1, wherein the reducing salt is sodium sulfite.

3. A composition in accordance with claim 1, wherein the reducing salt is sodium thiosulfate.

4. A composition in accordance with claim 1, wherein the reducing salt is sodium perborate.

5. A composition in accordance with claim 1, wherein the chlorine bleach is selected from the class of di or tri chlorinated isocyanurates and mixtures thereof.

6. A composition in accordance with claim 1, wherein the amount of reducing salt is from 5 to 25 percent of the stoichiometric requirement for complete reaction with the bleach compound.

7. A composition in accordance with claim 1, which also contains an alkaline, water-soluble inorganic salt and mixtures thereof, other than said reducing agent.

8. A composition in accordance with claim 1, wherein the reducing salt is sodium or potassium hypophosphite.

9. The composition of claim 1 wherein the amount of chlorine bleaching agent provides in an aqueous medium 40 to 400 ppm available chlorine.

10. A composition in accordance with claim 1, which also contains a water-soluble organic surface active agent stable in the presence of the chlorine bleaching agent.

11. A composition in accordance with claim 2, wherein the chlorine bleach is a di or tri chlorinated isocyanurate and mixtures thereof.

12. A composition in accordance with claim 5, wherein the chlorine bleach is a mixture of potassium dichloroisocyanurate and trichloroisocyanuric acid in a ratio of 4:1.

13. A composition in accordance with claim 5, wherein the reducing salt is sodium or potassium hypophosphite.

14. A composition in accordance with claim 5, wherein the chlorine bleach is potassium dichloroisocyanurate.

15. A composition in accordance with claim 6, wherein the reducing salt is sodium sulfite and the chlorine bleach is a di or tri chlorinated isocyanurate and mixtures thereof.

16. A composition in accordance with claim 7, wherein the surface active agent is a C.sub.8 to C.sub.22 alkyl benzene sulfonate.

17. A powdered bleaching composition consisting essentially of a chlorine bleaching agent capable of liberating chlorine ions in an aqueous medium, a chlorine resistant optical brightener of the sulfonate triazole class and a water soluble reducing salt readily oxidizable in an aqueous medium by said chlorine bleaching agent, said chlorine bleaching agent being present in an amount to provide in aqueous medium from 40 to 400 ppm available chlorine, said optical brightener being present in an amount to provide in aqueous medium 3 to 10 ppm thereof and said reducing salt being present in an amount from 5 to 25 percent of the Stoichiometric requirement for complete reaction with said bleaching agent, said reducing salt being more readily oxidizable by said chlorine bleaching agent than said brightener.