Stabilized liquid hydrogen peroxide bleach compositions, Exams of Technology

Download Stabilized liquid hydrogen peroxide bleach compositions and more Exams Technology in PDF only on Docsity! © Publication number: 0 2 0 9 2 2 8 A 1 02) E U R O P E A N PATENT A P P L I C A T I O N (ay Application number: 86303980.6 © Int. CI.4: C1 1 D 3/39 , C1 1 D 3 / 3 9 5 © Date of filing: 27.05.86 © Priority: 17.06.85 US 745617 © Applicant: The Clorox Company 1221 Broadway @ Date of publication of application: Oakland California 94612(US) 21.01.87 Bulletin 87/04 © Inventor: Mitchell, James D. © Designated Contracting States: 320 East Angela Street BE CH DE FR GB IT LI LU NL SE Pleasanton California 94566(US) Inventor: Farr, James P. 4885 Harrison Street Pleasanton California 94566(US) Inventor: Carty, Daniel T. 50 Tyrrel Court Danville California 94526(US) © Representative: Ford, Michael Frederick et al MEWBURN ELLIS & CO. 2/3 Cursitor Street London EC4A 1BQ(GB) £) Stabilized liquid hydrogen peroxide bleach compositions. curopaiscnes fatentamt European Patent Office Office europeen des brevets (57) Aqueous peroxide bleaching compositions that include surfactant, fluorescent whiteners and dyes are effectively stabilized by the addition of a heavy metai chelating agent and a free radical scavenging agent. Both agents must be present to achieve maxi- mum stability. Particularly preferred chelating agents are the amino polyphosphonates. Particularly pre- ferred free radical scavenging agents are the hydrox- ybenzenes and especially substituted phenols. Not only is the peroxide oxidizing agent stabilized, but surfactant, fluorescent whitener, and dye as well. w N Ti u erox Copy Centre 1 0 209 228 2 STABILIZED LIQUID HYDROGEN PEROXIDE BLEACH COMPOSITIONS This invention relates to household fabric bleaching compositions, but more particularly to liquid peroxide, e.g., hydrogen peroxide based bleaching compositions including additional ad- juncts such as surface active agents, fluorescent whiteners, and dyes. The bleaching compositions have the peroxide and certain adjuncts therein sta- bilized by the addition of agents to chelate heavy metal cations and scavenge free radicals. Liquid bleaches have been used in households for at least 50-75 years as aids in the bleaching and cleaning of fabrics. Hypochlorite bleaches have been used most extensively for this purpose since they are highly effective, inexpensive and simple to produce. In an attempt to broaden and extend the utility of bleaches for household use, other bleach sys- tems have been introduced in recent years. Promi- nent among these are dry powdered or granular compositions, most usually based upon peroxy- compositions; or upon perboro-compositions. Such materials must be placed into aqueous solution to release the bleaching action. Liquid bleaching compositions utilizing peroxy compounds have generally been utilized less in the household market than the solid forms referred to above. Although hydrogen peroxide compositions effectively bleach a broad range of fabric materials; are less harsh than hypochlorite bleaches; and do not release objectional gases or odors; they have not found as much use in the household market as hypochlorite bleaches. This lack of use in the household market has been partially attributable to the instability of peroxide solutions. This instability is mediated principally by metal ion contamination even in extremely low concentrations. Considerable effort has been expended in the search for stabiliz- ing agents for hydrogen peroxide compositions. Perhaps one reason why stabilized hydrogen peroxide compositions have not been successful is the fact that it is very desirable to add other or- ganic components to commercial bleaching com- positions, especially where the compositions are intended to be used as "pre-spotters". Such "pre- spotter" compositions most advantageously include surfactants for their detergent effect; fluorescent whiteners (also known as optical brighteners) to increase fabric reflectance and the user's percep- tion of increased whiteness; and dyes for produc- ing a pleasing color to the bleach solutions. All of the above components, in addition to the bleach compounds themselves have been found to be necessary in a liquid peroxygen bleaching com- position to achieve full acceptance in the house- hold market. Unfortunately liquid bleaching compositions based upon peroxide not only deteriorate from the presence of contaminants, e.g., trace metal cations (0.5ppm or greater); but the surfactant, fluorescent 5 whiteners, and dyes are attacked by the peroxide itself, as it is a powerful oxidizing agent. Thus peroxide based bleaching compositions including surfactants, fluorescent whiteners, and dyes dete- riorate quite rapidly. The surfactants are oxidized 70 and lose their detergency; the fluorescent whiten- ers are oxidized and lose their effect; and the dyes are oxidized and lose their color, or are changed to undesirable colors. The present invention is directed to methods 75 for stabilizing liquid hydrogen peroxide based com- positions, and more especially to stabilizing liquid peroxide bleaching compositions that also include surfactants, fluorescent whiteners, and dyes. The invention is also directed to compositions produced 20 by such methods. More particularly the present invention relates to liquid hydrogen peroxide bleaching compositions (including the aforementioned additional compo- nents) that are stabilized by the addition of a metal 25 chelating agent as well as a free radical scavenging agent thereto. The presence of both the chelating agent and free radical scavenging agent are neces- sary to achieve the desired stability. The metal chelating or sequestering agent may 30 be selected from among the known metal chelating agents. A preferred group of such chelating agents are the amino polyphosphonates which are known to sequester metal ions such as Fe+ + * and Cu + + . The free radical scavenging agent may be se- 35 lected from organic antioxidants, especially the substituted mono-and di-hydroxybenzenes and their analogs. Stabilization of hydrogen peroxide composi- tions including the associated fluorescent whiteners 40 (also known as optical brighteners), surfactant, and dye components relies upon the presence of both the metal chelating agent and the free radical scavenging agent. The stabilizing agents need only be present in very small amounts, e.g., tenths to 45 hundredths of a percent by weight of the liquid composition, in order to effectively prevent deterio- ration and retention of the desired strengths of the various components over extended periods of time. As utilized herein, "stabilization" refers to the so retention of physical and chemical properties at, or somewhat below their initial levels by each of the liquid bleach composition components for extended periods of time; and a significant reduction in the . rate of deterioration of such components in com- parison to unstabilized formulations. Thus, in the 2 0 209 228 8 agent ana tne Tree raaicai scavenger appears to possess synergistic action in improving stability of liquid peroxide compositions containing organic components. Referring to the stabilized peroxide composi- tions of the invention, a peroxide source is present as the principal active ingredient and functions as the bleaching agent. The peroxide is normally present as hydrogen peroxide and is present in the range of about 0.05-50 weight %, most usually at about 0.1-35 wt.%, and most preferred at 0.5-15 wt.%. The hydrogen peroxide is a staple article of commerce available from a number of commercial sources. In making up the bleaching compositions, ordinarily the peroxide is purchased as a con- centrated aqueous solution, e.g., 70%, and diluted with deionized water to the desired strength. The FMC Corp. of Philadelphia, Pennsylvania is one source of hydrogen peroxide. Surfactants are desirable for use in the bleach- ing compositions. Not only do they perform the normal soil removing function; but, in the present formulations, they also assist in emulsifying the free radical scavenger into the aqueous bleach formulation. As will be noted hereinafter, the free radical scavenger component is somewhat hydro- phobic. The surfactant therefore assist mixing of free radical scavenger into the bleach composi- tions. As will be also noted hereinafter, the surfactant component can provide a thickening effect; espe- cially when used in higher concentrations, such as when exceeding about 5 wt.%. The most preferred surfactants are nonionics. Suitable nonionics include polyethoxylated alco- hols, ethoxylated alkyl phenols, polyoxyethylene or polyoxypropylene block co-polymers, anhydrosor- bitol esters, aikoxylated anhydrosorbitol esters, and the like. Other potentially suitable surfactants are disclosed in the Kirk-Othmer Encyclopedia of Chemical Technology. 3rd Edition, Volume 22, pp. 360-377 (1983), the disclosure of which is incor- Dorated herein by reference. Such nonionic surfac- tants may be obtained from any number of com- Tiercial sources. One such source for polyethox- ylated alcohols is the Shell Chemical Co. of Hous- :on, Texas and are known under the tradename "Neodol". One suitable surfactant is "Neodol 25- f"\ This Neodol is an ethoxylated alcohol, wherein tie alcohol has from 12-15 carbons to which 7 3thoxy groups are attached. Anhydrosorbitol esters Including sorbitan esters) are available from Atlas Dhemical Industries under the tradenames Tween" and "Arlacel". The surfactant may be present in the composi- ions in about 3-4 weight %, although this level is lot critical. Lower, or higher surfactant concentra- ions are acceptable within the ranges noted. The preferred range for surfactant is 0-50 wt.%; the more preferred range is 0-20 wt.%; and the most preferred range is 0-10 wt.%. At higher levels, and, as noted above, the surfactants may beneficially 5 have a thickening effect on the liquid compositions. Such thickening would aid in the dispersion of particulate components such as dyes and whiten- ers. Also, as noted above, the surfactants may also assist in emulsifying the liquid compositions and to aid in the suspension of some of the free radical scavengers since they tend to be somewhat insolu- ble in aqueous medium. Mixtures of the surfactants are also suitable. Fluorescent whiteners (also referred to as op- 75 tical brighteners, or FWA's) are also included in the bleaching formulations. Such whiteners are also common commercial products. Such products are fluorescent materials, very often substituted stii- benes and biphenyls, having the ability to flu- 20 oresce, by absorbing ultraviolet wavelengths of light, and then emitting visible light, generally in the blue wavelength ranges. The whiteners settle out or deposit onto the fabrics during the bleaching or washing process to thereby impart the desired 25 whiteness. The whiteners may be present in the bleaching compositions in the order of several hun- dredths to about 5 wt.%, more preferably 0-1 wt.%, and most preferably 0-0.6 wt.%. One source of such whiteners is the Ciba Geigy Corp. of Greens- jo boro, North Carolina, under the tradename "Tinopal". Other useful whiteners are disclosed in U.S. Patent 3,393,153 to Zimmerer et. al., at col- umns 3-5, which disclosure is incorporated herein by reference. ?5 Several different whiteners may be combined in the compositons. Such selection is governed by the fact that certain whiteners have affinity for cel- lulose fibers, e.g., cotton; while others have affinity for synthetic fibers, e.g., nylon. Since the bleaching to compositions of the invention are intended for all types of fabrics, both natural and synthetic, it is advantageous to include whiteners of both types. One stilbene based product, "Tinopal RBS" has affinity for synthetic fibers. A distyrylbiphenyl prod- is uct "Tinopal CBS-X" has affinity for cellulose fi- bers. Small amounts of dye are also included in the preferred bleaching compositions. While the dye is only a very small percentage (perhaps 0.0005) of ;o the compositions, it plays an important part in consumer's acceptance of the product. It is pre- ferred that such dye be present in the range of 0-1 wt.%, more preferably 0-0.1 wt.%, and most prefer- ably 0-0.001 wt.%. Dyes such as the anth- 5 raquinones are particularly suitable. Such anth- raquinone dyes are available from the Sandoz Co. of Charlotte, North Carolina. One suitable dye is "Nylosan 2AL" from the aforementioned company. g 0 209 228 10 Other dyes of the desired color with resistance to bleaching can also be used. In some instances, inorganic pigments may be used. Such preferred pigments are those which have the metallic cations substantially or completely complexed, e.g., copper phthalocyanines. A fragrance may also be used in the bleaching formulations, if desired. Any fragrance oil may be used, ordinarily in small quantities, e.g., 0.01%, so long as it is as stable as the other components. The preferred range is 0-5 wt.%. The more pre- ferred range is 0-1 wt.%; while the most preferred range is 0-0.1 wt.%. In addition to the aforementioned components, buffer is added to the composition in order to adjust the final pH into the 1-8 range, more prefer- ably 1-6, and most preferably 2-4. Phosphoric acid Is preferred for this purpose when acidic pH is desired. pH can be adjusted by proper amounts of acid or base. As noted above, the stabilizing system is vital to the bleaching compositions. Both the chelating agent and the free radical scavenger must be present. Tests have shown that neither agent is as effective individually as when present in combina- tion. Synergistic forces are obviously involved in the stabilization, and prolonged stability of the bleaching compositions results only when both 5 agents are present. The chelating agent may be selected from any number of known agents with the caveat that any agent selected must be effective in chelating heavy metal cations, such as Cu + +and Fe+ + + . The 70 chelating agent should also be resistant to hydroly- sis; and not easily oxidized by hydrogen peroxide. Preferably it should have an acid dissociation con- stant, i.e., pKa of about 1-9, indicating that it dis- sociates at low pH's to permit bonding to the metal 75 cations. In this regard, the amino polyphosphonates have been found to be most useful in the present bleaching compositions. The amino poly- phosponates are commercially available com- 20 pounds sold under the trademark "Dequest" by the Monsanto Co. of St. Louis, Missouri. These com- pounds have structures such as: 25 ( H 2 0 3 P C H 2 ) 2 - N - C H 2 - C H 2 - N - ( C f ^ P O ^ ) 2 C H 2 P 0 3 H 2 H 2 0 3 P C H 2 - N - C H 2 P 0 3 H 2 and: ( H 2 0 3 P C H 2 ) 2 - N - ( C H 2 ) 2 - N - ( C H 2 ) 2 - N - ( C H 2 P 0 3 H 2 ) 2 C H 2 P Q 3 H 2 45 Such "Dequest" compounds are extremely ef- fective as chelating agents in the bleach composi- tions. Other related chelating agents such as the pyrophosphates may also be utilized. The selected chelating agent should be present in the compositions in an amount sufficient to thor- oughly tie up any heavy metal cations present in the aqueous solution. One or two tenths of a per- cent is sufficient. The chelating agent may be present in the range of 0.02-5 wt.%. The more preferred range is 0.04-0.3 wt.%. The most pre- ferred range is 0.06-0.12 wt.%. 50 55 The second vital stabilizing agent is the free radical scavenger. For this purpose, the substituted phenols, or more broadly, hydroxybenzenes are preferred. Of this class of compounds butylated hydroxy toluene (BHT) and mono-tert-butyl hydroquinone (MTBHQ) have been found to be especially effective. The free radical scavengers must resist oxida- tion by Hj05 and therefore, cannot be too strong a reducing agent. Strong reducing agents would more likely react with the peroxide. 6 11 0 209 228 12 nnaiiy it is aesiraoie tnat the free radical scavenging hydroxybenzenes be partially hindered, i.e., have a substituent alkyl or similar group at- tached to some of the reactive sites on the ring structure. If too many reactive sites are left un- blocked, it may be possible to react with more than one available free radical and polymerize, thus causing phase separation. Any such phase separa- tion is undesirable and would remove free radical scavenging agent from the bleach solution. The aforementioned BHT and MTBHQ satisfy all the above criteria and are therefore preferred as the free radical scavenging agent. BHT is commer- cially available from the Uniroyal Chemical Co. 5 while MTBHQ is commercially available from the Eastman Chemical Co. of Kingsport, Tennessee. Only very small amounts of the free radical scavenger are necessary in the bleach composi- tions. Generally, one to several hundredths of a w percent provides effective free radical scavenging. The preferred range is 0.005-0.04 wt.%. The more preferred range is 0.007-0.03 wt.%; however the most preferred range is 0.01-0.02 wt.%. As an example, a typical stabilized bleach for- 15 mutation is set forth below: e & h U L A & h U S T A B I L I Z E D BLEACHING F O R M U L A T I O N S C o m p o n e n t Nonion ic s u r f a c t a n t ( N e o d o l ) F l u o r e s c e n t w h i t e n e r - d i s t y r y l b i p h e n y l - s t i l b e n e Blue dye - a n t h r o q u i n o n e F r a g r a n c e H Z ° 2 P h o s p h o n a t e c h e l a t i n g a g e n t Free r a d i c a l s c a v e n g e r P h o s p h o r i c a c i d ~ d e i o n i z e d m numDer or tests were performed to ascertain the effectiveness of the stabilizing system of the aresent invention. Several samples of hydrogen seroxide bleach compositions were prepared hav- ng variations in components and percentages thereof. *5 Wt. % 2- 4 0 . 1 - 0 . 7 0 . 0 1 - 0 . 3 0 . 0 0 0 2 - 0 . 0 0 1 0 . 0 1 3- 7 0 . 0 6 - 0 . 2 5 0 . 0 0 5 - 0 . 0 2 s u f f i c i e n t t o a d j u s t pH to 2 . 3 ' r e m a i n d e r 1 One formulation had the composition: 5 1 / 0 209 228 18 5 70 70 FORMULATION B T a b l e 2i 4 Week S t o r a g e S t a b i l i t y T e s t 120° F ioo° F B l e a c n F o r m u l a t i o n B l e a c h F o r m u l a t i o n o i e a c n + u e q u e s t a c h + D e q u e s t l a t i o n + BHT l a t i o n + B H T , ( u n s t a b i l i z e d ) + l p p m Fe + l p p m Cu C ( U n s t a b i l i z e d ) + l p p m Fe 3+ lppm Cx (•s r e m a i n i n g ) (% r e m a i n i n g ) (% r e m a i n i n g ) - (% r e m a i n i n g ) _ + _ B ^ 3 . , _ H 2 U 2 W h i t e n e r D y e 28 43 99 93 80 96 68 72 99 100 98 J5 in anotner sway, similar aging tests were con- Jucted for a period of eight weeks at storage emperatures of 70 °F, 100°F, and 120°F. Table 3 )elow presents the results of these longer aging ests. 5 0 19 0 209 228 20 FORMULATION B Table 3: 8 Week Stability T e s t 1 Storage Temp. 70°F 100°F 120°F *2 3 *2 3 *2 Component S Uns. S Uns. S U n s , H2Oz 100 92.3 97 77 96 56 Whitener 100 57 94 13 56 10 Dye 96.8 51 83 0 55 0 The numbers shown r e p r e s e n t the % of the component remaining a t the end of the test p e r i o d . "S" ind ica tes stabilized composi t ion "Uns" indicates uns tabi l ized composit ion in some further tests, stabilized samples of Formulation B and C above were aged at various temperatures in order to follow the deterioration of the various components with time. Catalyzing metal cations (5 ppm) were added to the stabilized for- mulations. The results are set forth in Table 4 and 5 below: 35 to >o 1 21 0 209 228 22 F O R M U L A T I O N C T a b l e 4: 8 Week S t a b i l i t y T e s t S t o r a g e T e m p . ; 100°F ' 1 2 0 ° F C o m p o n e n t H 2 ° 2 W h i t e n e r D y e 96 97 77 95 74 48 *The n u m b e r s shown r e p r e s e n t the % of the c o m p o n e n t r e m a i n i n g a t end of t e s t p e r i o d . F O R M U L A T I O N B T a b l e 5: 8 Week S t a b i l i t y T e s t S t o r a g e T e m p . 1 0 0 ° F C o m p o n e n t H 2 ° 2 W h i t e n e r D y e 98 87 77 The n u m b e r s shown r e p r e s e n t the % of the c o m p o n e n t r e m a i n i n g a t end of t e s t p e r i o d . A review of the data present in Tables, 1 , 2, 3, 4, and 5 reveals that when the peroxide composi- tions were stabilized with both the chelating agent and free radical scavenger, significantly more H202, whitener, and dye remained at all aging tempera- tures as compared with unstabilized composition. It should be noted from Table 1 that the addi- tion of the chelating agent alone, or the free radical scavenger alone, did not stabilize the compositions nearly as well as did the addition of both chelating 45 50 agent and free radical scavenger. These data clear- ly indicate that both the chelating agent and the free radical scavenger must be present in order to optimize the composition's stability. Another test was conducted on a simplified peroxide formulation omitting surfactant and whit- eners. It was intended to ascertain whether the presence of surfactant was necessary to achieve good stability. The formulation was: 55 12