US3398096A - Low temperature bleaching composition - Google Patents

Description

-ABSTRACT OF THE DISCLOSURE A stable dry catalyst powder fore-nhan-cing the bleaching action of water-soluble inorganic p'ercompounds at 'low temperatures of 2050 C. Comprising a metal-ion of a transition element and a water-insoluble or hardly solu'ble powdered carrier, processes for the preparation thereof and percompound bleaching compositions containing the catalyst powder.

The invention relates to ion/carrier catalysts, to .processes for the preparation of ion/carrier catalysts and to bleaching compositions containing these catalysts. In particular, the invention relates to ion/ carrier catalysts which affect the bleaching actionof inorganicprecompounds to such an extent that effective bleaching at relatively low temperatures, e.g. 2050 C., can be achieved and to their preparation in a suitable and stable form andto their use in bleaching compositions. Such catalysts can be ad vantageously used 'in bleaching compositions containing inorganic percompounds, e.g. perborates or persulphates, to obtain low-temperature bleaching and find particular use in scouring powder formulations containing inorganic percompounds.

It isknown that certain cobalt and manganese salt solutions when freshly adsorbed on asuitable carrier, such as the alkaline carbonates of calcium,-magnesium, zinc or cadmium, exercise ahighly catalysing effect on the bleaching action of hydrogenperoxide. Such freshly prepared systems when mixed with a hydrogen peroxide solution have a bleaching effect on certain-dyestuff solutions at room temperature.

Known low-temperature bleaching compositions generally contain a chlorine-releasing compound, such as dichlorocyanuric or trichlorocyanuricacid, which has the disadvantageuof spreading a disagreeable chlorine smell, which persists for .some time after use, especially on the skin, and the further disadvantage of sometimes attacking the fibres of textiles, especially of some finished fabrics.

Another disadvantageconnected with compositions based on chlorine bleache-s is their instability on storage, resulting in a decrease of bleaching effect. These disadvantages are not presentto the same extent with bleaching compositions based on inorganic percompounds, such as perborates or persulphates. However, inorganic percompounds are relatively inactive bleaching agents at low temperatures, e.g. 20-50" C. Their bleaching effect increases with increasing temperature and attains its maximum at the boil. e

It is an object of the invention to prepare stable catalysts as a dry powder having a free moisture content of less than 15%, preferably 15%, which can be incorporated in bleaching compositions containing inorganic percompounds and particularly in scouring powder bleach formulations containing inorganic percompounds.

It is also an object of the invention to provide low-temperature bleaching compositions which are effective in the removal of persistent stains, e.g. tea stains, from hard surfaces, such as dishes, tiles and the like, and. which are r d, S ate P te ice also useful for bleaching stains on fibrous materials, such as finished and unfinished textile fabrics.

Another object is to provide detergent compositions especially for dishwashing containing inorganic percompounds having low-temperature bleaching properties A further object is to provide scouring powder compositions containing inorganicpercompounds, e.g. sodium perborate, having a bleaching effect comparable with those compositions containing chlorine bleaches.

The catalysts according to the invention comprise a metal ion adsorbed on a suitable inorganic carrier. The metal ions themselves in a non-adsorbed form may or may not have any effect on the bleaching activity of the inorganic percompound. However, when suitably adsorbed on suitable carriers these metal ions increase the bleaching activity to a large extent. It has been found that the metal ions of the transition elements in the periodic system especially those having an unpaired electron spin, such as Co Mn Ni Cr M0, or Ca are particularly-etfective. The carriers which can be advantageously used may be any water-insoluble or slightly soluble compound of Zn, Cd, Ca, Mg, Al, Sn, Be, Ti, Sb, Bi or SiO Of these possible combinations the most active catalysts are found when Co is adsorbed on: zinc silicate; titanium dioxide or hydroxide; tin dioxide; antimony trioxide; aluminium oxide, hydroxide or silicate; alkaline zinc carbonate; alkaline cadmium carbonate; cadmium carbonate, silicate or oxide. The metal-ion content may be from 1-100 mg. or more per gram catalyst, and preferably from 20-60 mg./ g. It goes without saying that the catalysts according to the invention are also effective to aid the bleaching action of inorganic percompounds on coloured solutions at low temperature.

The catalysts according to the invention may be prepared in the following ways:

(a) By dry-mixing a finely-divided powdered salt, e.g. CoCl containing the metal ion, with the finely-divided carrier in such a way that a homogeneous mixture is obtained, in which both substances are in very good contact.

(b) By adding an aqueous solution containing the metal ion, e.g. CoCl solution, to the required amount of finely powdered carrier. Water is then added and the whole mixture is stirred until a paste-like substance is obtained. The product is then dried at temperatures up to about C.vacuum may or may not be applied preferably at temperatures of 4060 C. in a vacuum of 1-15 mm. Hg. Much higher temperatures may also be applied, depending on the type of catalyst, although it is not advisable since it would affect the catalysts activity.

(0) By freeze-drying the paste-like substances as described in (b), at temperatures of 50 to 0 C. in a vacuum of 001-1 mm. Hg.

The catalysts obtained by the aforementioned methods assist bleaching at low temperatures (20 C. or even lower), as well as at higher temperatures, with sodium perborate and/ or with other inorganic percom-pounds including percompounds, such as Du Ponts Oxone (a triple salt consisting of potassium permonosulphate, potassium hydrogen sulphate and potassium sulphate in the approximate molecular ratio of 2:1:1).

It is desirable that the bleaching compositions should give an alkaline solution, preferably one having a pH value of between 7 and 11 It has been found that catalysts prepared according to the process of the present invention can be stored for some time without losing their activity. They can be drymixed with inorganic percompounds to form low-temperature bleaching compositions, preferably at weight ratios of between 1: 1 and 1:8. Such mixtures when incorporated in normal detergent compositions enable the latter to bleach effectively at relatively low temperatures. It has also been surprisingly found that the catalysts obtained from the freeze-drying process (process (c)), especially those with zinc compound carriers, are much more ac- These compositions were tested at room temperature for the bleaching of tea stains on unglazed tiles (Royal Sphinx Maastricht, 15 x 15 cm.) by applying them as a paste-like substance to the tile surface. The following test tive than the catalysts prepared from the same com- 5 method was used: pounds according to process (a) or (b)- Their ac ivity, The reflectance of a tea-stained tile was measured. however, decreases on storing under normal room condigrams powder were mixed with 7 ml. distilled water and tions to values approaching those of catalysts prepared stirred for 30 seconds. The mixture was poured on the tile according to the other processes of the invention. By a surface. After a contact time of 1 or 2 minutes the paste suitable coating of the particles it would be possible to 10 was rinsed from the tile surface with running tap water retain his extremely high activity originally obtained. Catfor at least 10 seconds. After standing in the air for about alysts prepared with carriers havingaparticle size of 30-52 24 hrs. the reflectance of the tile was measured again. mesh (British Standard Sieve) are especially suitable for In the following table the increase in reflectance of the tile coating. surface after treatment is given. From this table it can be The catalysts prepared according to the processes of seen that the type of carrier used is an important factor. the invention can be mixed with inorganic percompounds e.g. sodium perborate, to form stable low-temperature TABLE H bleaching compositions. They can also be incorporated in Increase inreflectance detergent powder formulations having a percompound Commsitlon Carrier Percent after time content of up to 30% and also in scouring powder com- 1min. 2min. positions with a percompound content of 120%, pref- I Zinc Silicate 27 42 erably 5-15 of sodium perborate. When used in scour- Cadmium carbonate 27 29 ing powder formulations it is preferable that the catalyst ififgggggagzz 3; 3 be added to the powder as the last component under Zincsilicate 26 30 thorough mixing. It is also preferable that the moisture Zmc g content of the detergent powder or scouring powder be 0 5 as low as possible. a

In order to avoid unwanted colouring of the bleaching by pf s 21 0 pared by dry mixmg' The othel catalysts were prepared solution and of the object to be bleached, which may be caused by the catalysing metal ion, sequestering agents Example 3 Y be incorporated in the bleaching composition The first four of the compositions referred to in Table sodlilm hexametfllhmRhateother Condensed phosphates II above were stored at room temperature in closed vessels particularly sod um tripolyphosphate, app reduce for two months and their bleaching effect again deterthe catalysts, actwlty' mined in the same way as described in Example 2. The Example 1 following results show that the compositions retained their bleaching activity during storage: Catalysts having a cobalt content of approximately 4% mg./ g. catalyst) were prepared in the following TABLE III wags; 100 fl 1 d d H t (100 h 40 [Results obtained after storage for 2 months] a g. ne y pow ere zinc s rca e mes British Standard Sieve) and 19 g. Co'Cl -6H 0 were Composition Carrier iii d iliiififii c t tih fii mixed together in a mortar so that a homogeneous mixture was obtained. The zinc silicate was previously dried in an oven at 80 C. under vacuum for one hour. 4 I gg g f f ig g (b) To 200 g. finely powdered ZlIlC silicate (100 mesh I Stannlc oxide 22 23 British Standard Sieve) a solution of 38 g. CoC1-6H O Antlmony oxlde 27 28 was added in 180 ml. Water and the mixture was stirred so that a homogeneous paste was obtained. Part of the What is claimed is, ji thenhdned li g z g 1. A process for the preparation of a stable dry catalyst E g Ours t e E a t y g; i i powder for enhancing the bleaching action of water solue graim es m mm at a a CB mols me C n en 0 ble inorganic percompounds at low temperatures in which 'approxlmately an aqueous solution of a salt containing a metal-ion (c) The other part of E paste was dned at gg selected from the group consisting of the transition eleperature of less i 20 and at a pressure 0 merits in the periodic system is added to a powdered car- The molsture content of the product was aprier selected from the group consisting of water-insoluble proxlmalwly or hardly soluble compounds of Zn, Cd, Ca, Mg, Al, Sn,

Examp 1e 2 Be, Ti, Sb, Bi and SiO; to form a homogeneous mixture A number f scouring Powder compositions were and the mixture is thereafter dried to a moisture content pared containing sodium perforate and catalyst prepared 60 of l n according to Example 1. For purposes of comparison two A Process for the p pf 0f 3 f y Powder compositions were also prepared, one without catalyst according Claim in Whlch the drymg 1S earned out and the other containing the metal ion without a carrier. at temperatures not exceeding C.

TABLE I Parts by Weight I II III IV Sodium dodecylbenzenesulphonate i% 5;.an;6:;:;::::::::::::" 815 1530 8:5 gggggg g gg%%ggjgg Catalyst, containing 4% 00 4. 0 4. 0 C0 012 without a carrier 3. A process according to claim 1, in which the drying is carried out under a vacuum of 1 to 15 mm. Hg and at a temperature of 40-60 C.

4. A process according to claim 1, in which the drying is carried out in the form of freeze-drying at a temperature of 50 to (l C. and at a vacuum of 0.01 to 1 mm. Hg.

'5. A low temperature bleaching composition consisting essentially of a mixture of the catalyst powder con sisting essentially of metal-ion selected from the group consisting of the transition elements in the periodic system which is adsorbed on or intimately mixed with a powdered carrier selected from the group consisting of water-insoluble or hardly soluble compounds Zn, Cd, Ca, Mg, A1, Sn, Be, Ti, Sb, Bi and SiO the metal-ion content being from about 1 to milligrams per gram of catalyst powder, and a water-soluble inorganic percompound, the weight ratio between the catalyst powder and the water-soluble inorganic percompound being from about 1:1 to about 1:8.

6. A detergent powder bleach and cleansing composi tion, for use in the presence of water, consisting essentially of the composition defined by claim 5 in amounts such that the water soluble inorganic percompound con tent is up to about percent by weight of said composition.

7. A detergent and scouring composition, for use in the presence of water, consisting essentially of the low temperature bleaching composition defined by claim 5 in an amount such that the water soluble inorganic percompound content is from about 1 percent to about 20 percent by weight of said composition.

References Cited UNITED STATES PATENTS 3,156,654 11/1964 Konecny et a1. 25299 3,207,696 9/ 1965 Shephard et a1. 252-186 3,211,658 10/1965 Hertz et a1. 252-99 LEON D. ROSDOL, Primary Examin r.

M. WEINBLATT, Assistant Examiner.