STABILISED PEROXIDE COMPOSITION AND METHOD OF PRODUCING THE SAME

Abstract: The invention provides a stabilised peroxide composi­ tion. The composition comprises succinyl peroxide admixed with a water-soluble stabilising agent which can function as a dehydrating agent but which does not react with succinyl peroxide, typically an inorganic compound in a partially hydrated form, which gives an acid pH in solution, for example, a partial hydrate of sodium or magnesium sul­ phate. The composition can be prepared by treating a paste of succinyl peroxide in water with a water-soluble dehydrat­ ing agent which does not react with succinyl peroxide, the dehydrating agent being employed in an amount sufficient to provide a dry mixture. The composition of the invention can be stored at ambient temperature with minimal decomposition.

Description: "STABILISED PEROXIDE COHPOSITION AND METHOD OF PRODUCING THE SAME" The present invention relates to a stabilised peroxide composition, in particular a composition comprising succinyl peroxide. Succinyl peroxide, which is also known as disuccinyl peroxide or succinic acid peroxide is a compound of the formula: (HOOC.CH2 CH2 CO)202 Succinyl peroxide is known for use as a polymerisation initiator, as a deodorant and as an antiseptic. In the past the compound has been sold in the dry powder form for use primarily as a polymerisation initiator, but it was found that the dry powder is friction sensitive and, under certain circumstances, could explode. In order to overcome this problem succinyl peroxide is now marketed as a 70 per cent by weight paste in water. However, succinyl peroxide as a paste in water is unstable at ambient temperatures, the peroxide decomposing by hydrolysis, and stability can only be ensured by storing the paste under refrigerated conditions, typically at -10 0C. It will be appreciated that the need to store and transport the paste under refrigerated conditions is a significant disadvantage, especially when the peroxide is required for use in applications where say relatively small unit doses of peroxide are to be stored before use, for example as an antiseptic. We have now wound surprisingly that an intimate mixture of succinyl peroxide and a water-soluble dehydrating agent which does not react with succinyl peroxide provides a composition which is stable on storage at ambient temperatures and which does not possess the friction sensitivity of dry, powdered succinyl peroxide per Se. Accordingly, the present invention provides a stabilised peroxide composition, which composition comprises succinyl peroxide admixed with a water-soluble stabilising agent which can function as a dehydrating agent but which does not react with succinyl peroxide. In the compositions of the invention the stabilising agent must be one that is water soluble and one that is sufficiently inert not to react with succinyl peroxide. The stabilising agent must also be capable of functioning as a dehydrating agent, and in particular, is preferably a dehydrating agent which can or does include water bound as water of crystallisation. Moreover, since the creation of a high pH could cause the succinyl peroxide to decompose, additionally it is preferred that the stabilising agent should generally be one capable of providing an acid pH in solution, preferably a pH of below 5, for example, about 4 to about 2.5. Most preferably the stabilising agent does not materially alter the pH of succinyl peroxide in solution. Preferred dehydrating agents are inorganic compounds which can exist as partial hydrates and especially preferred dehydrating agents are sodium and magnesium sulphates, which may be used in anhydrous form or more preferably in a partially hydrated form. Of these dehydrating agents magnesium sulphate is the most preferred, in particular as MgS04.nH20, wherein n has a value of from about 2 to less than 7, preferably about 2 to about 3. In the compositions of the invention it is preferred that for every 1 part by weight of succinyl peroxide the composition should comprise from abou-t 0.1 to about 12.5 parts by weight of bound water and from about 1 to about 50, preferably from about 1 to about 25, parts by weight of a dehydrating agent. More preferably, the proportion of bound water is from about 0.4 to about 1.0 parts by weight and the dehydrating agent is present in a proportion of from about 1.0 to about 3.5 parts by weight1 and most preferably the proportion of bound water is about 0.4 to about 0.7 parts by weight and the dehydrating agent is present in a proportion of from about 1.1 to about 2.2 parts by weight. The compositions of the invention suitably may be prepared by mixing a dehydrating agent with an aqueous paste of succinyl peroxide, typically.the 70% by weight paste now commercially available. Accordingly,the invention also provides a method of producing succinyl peroxide in a stable particulate solid form whereby it may be stored at ambient temperature with minimum decomposition, which method comprises treating a paste of succinyl peroxide in water with a water-soluble dehydrating agent which does not react with succinyl peroxide, the dehydrating agent being employed in an amount sufficient to provide a dry particulate solid mixture, preferably a dry powder. In the method of the invention the aqueous paste of succinyl peroxide typically will be the about 70% by weight paste in water which is commercially available, although pastes having a peroxide content generally down to about 40% by weight, typically down to about 50% by weight, may be employed, and the upper limit of peroxide may, if desired, be up to about 90%* While the content of the paste will usually depend on the most convenient manufacturing source available in any particular instance, whatever the content of the paste used it can be treated to provide a dry mixture by mixing generally with from about 40 to about 95% by weight of dehydrating agent, preferably a sodium or magnesium sulphate as described above, based on the total weight of dehydrating agent and the paste. Preferably from about 45 to about 80% by weight of dehydrating agent is employed based on the total weight of dehydrating agent and paste. Where the dehydrating agent employed is a partially hydrated material it is to be understood that the amount employed may have to be increased in proportion to the degree of hydration of the agent. Also, since the dehydrating agent acts to remove water from the paste the level of hydration (if any) 7.:1 the dehydrating agent will initially be below that mertioned above in connection with the compositions of the invention. Thus, in the case of hydrates of magnesium sulphate, in the formula ugS04.n'H20 the value of n' wil: be less than the corres ponging values for n mentioned Roove, and typically n' will have a value of from about T to about 4, preferably from about 1 to about 2. Preferably, the dehydrating agent is employed as a fine powder1 and the treatment ry be effected by simple mixing for a suitable time to provide a dry mixture. Generally a mixing time of from ibout 15 minutes to about 6 hours will be sufficient, and typically a mixing time of from about 30 minutes to about 4 hours may be employed. In the method of the invention, the amount of dehydrating agent and the mixing time generally are adjusted so that there is produced an intimate mixture of ingredients in particulate solid form which gives the appearance of a dry solid, for example, a dry powder. Such a dry solid is a dry mixture of the kind required herein whether or not the mixture as a whole is dry in any absolute sense. Thus, provided any water present is captured by dehydrating agent and is not free to wet the peroxide, the mixture is dry. In preparing the compositions of the invention other optional ingredients may be included as and when desired. Thus, the compositions may include one or more detergent materials, chelating agents, hydrogen peroxide donors, e.g. urea hydrogen peroxide adduct or sodium perborate, and colouring agents. For example, the compositions may include from about 1% to about 2% by weight of a solid anionic, e.g. sodium lauryl sulphate, or non-ionic detergent, and colour may be provided using either a dye-stuff or a pigment, e.g. ultramarine. In particular, the compositions preferably may include a dyestuff (typically one giving a blue colour) which is stable in the presence of succinyl peroxide when in aqueous solution at dilutions such as those mentioned below. As an example of such a dyestuff there may be mentioned the copper phthalocyanine complex C.I. Acid Blue 254. The compositions of the present invention are biocidal, and accordingly are useful as cleaning and/or disinfecting and/or sterilising and/or antiseptic compositions. The compositions by virtue of the fact that they contain succinyl peroxide are not only bactericidal but also fungicidal, sporicidal and perhaps viricidal. In particular, the compositions of the invention may be used as general purpose hard surface cleaners, as instrument sterilisers, or as a replacement for lodophor. Moreover, because the compositions are in a stable dry powder form, they may be packaged for distribution, storage and use without any special restrictions being imposed on transport and storage conditions. As shown below the compositions remain in an active condition even after a storage period well in excess of one year. When required for use the compositions are dissolved in water at a high dilution, typically at a dilution of from 0 05% to 2% w/w (based on a succinyl peroxide content of about 20% by weight) and are used immediately after they are made up in diluted form. Following is a description by way of example of the preparation of stabilised peroxide compositions in accordance with the invention Example 1 0.2 kg of a 70% by weight succinyl peroxide paste in water obtained from Laporte Industries were mixed with various proportions of sodium and magnesium sulphate to obtain a dry mixture. The dehydrating agent employed, its amount and the mixing conditions and time are shown in Table 1 below: TABLE 1 %w/w Succinyl % w/w Sodium Mixing Mixing Peroxide as a Sulpahte Sulphate Conditions Time 70% w/w paste Monhydrate -Anhydrous in water 10 90 - Tumble mixer 4 hours 20 80 - Tumble mixer 4 hours 30 70 - Tumble mixer 4 hours 50 50 - Tumble mixer 4 hours 10 - 90 Tumble mixer 4 hours 20 - 80 Tumble mixer 4 hours 30 - 70 Tumble mixer 4 hours Under storage conditions at ambient temperature each of the above-prepared dry mixtures gave results which indicated that a shelf life in excess of one year can be obtained in accordance with the present invention. In this connection, and by way of example, reference is made to the accompanying drawing which shows a graph of activity vs. time for a 70% by weight succinyl peroxide paste in water compared with two of the dry mixtures prepared as described above. The results expressed graphically were obtained from batches stored at about 20 C, the % w/w of succinyl peroxide being determined by sampling at suitable intervals and estimating the remaining succinyl peroxide by standard iodometric methods. In the drawing, curve A shows the activity of the 70% paste, from which it can be seen that activity decreases to a low level within about 60 days and at about 90 days the activity is so low as to be virtually not measurable. By contrast line B (mixture of 30% w/w of 70% paste with 70% wlw magnesium sulphate monohydrate) and line C (mixture of 30% w/w of 70% paste with 70% w/w anhydrous sodium sulphate) show that in accordance with the present invention activity is maintained at a significant level over a much longer period of time. Example 2 50 parts by weight of a 70% by weight succinyl peroxide paste in water obtained from Laporte Industries were mixed with 50 parts by weight of magnesium sulphate monohydrate to obtain a dry mixture. The initial succinyl peroxide assay given by the paste was 33.3% w/w and after 14 months of storage at ambient temperature the mixture gave a succinyl peroxide assay of 31.6% w/w. Example 3 A large scale batch of 50 kg of a stabilised peroxide composition was prepared by mixing 20 kg of a 70% by weight of succinyl peroxide paste in water with 30 kg of magnesium sulphate dihydrate to form a dry mixture. The dry mixture was then packed as 5 kg lots in polyethylene bags and those in turn were stored in a fibre board drum. The initial succinyl peroxide assay given by the paste was 29.02w/w. After mixing and storage at ambient temperature for one month there was an initial drop in the assay to a figure of 27.0% w/w, but after a total of 5 months' storage at ambient temperature the succinyl peroxide assay remained at 27.0% w/w.

Claims: CLAIMS 1. A stabilised peroxide composition which composition comprises succinyl peroxide admixed with a water-soluble stabilising agent which can function as a dehydrating agent but which does not react with succinyl peroxide. 2. A composition according to claim 1, wherein the stabilising agent is an inorganic compound in a partially hydrated form which gives an an acid pH in solution preferably of below 5, and preferably is a partial hydrate of sodium or magnesium sulphate. 3. A composition according to claim 2, wherein the stabilising agent is MgS04.nH20, where r. has a value of from about 2 to less than 7, preferably of from about 2 to about 3. 4. A composition according to any one of the preceding claims which for every 1 part by weight of succinyl peroxide comprises from about 0.1 to about 12.5 parts by weight of bound water and from about 1 to about 50 parts by weight of a dehydrating agent, preferably from about 0.4 to about 1.0 parts by weight of bound water and from about1.0 to about 3.5 parts by weight of dehydrating agent, more preferably about 0.4 to about 0.7 parts by weight of bound water and from about 1.1 to about 2.2 parts by weight of dehydrating agent. 5. A composition according to any one of the preceding claims, which also includes one or more detergent materials, chelating agents, hydrogen peroxide donors and colouring agents. 6. A composition according to claim 5, which includes from about 1% to about 2% by weight of a solid anionic or non-ionic detergent and/or a dyestuff stable in the presence of succinyl peroxide in dilute aqueous solution. 7. A method of producing succinyl peroxide in a stable particulate solid form whereby it may be stored at ambient temperature with minimum decomposition, which method comprises treating a paste of succinyl peroxide in water with a watersoluble dehydrating agent which does not react with succinyl peroxide, the dehydrating agent being employed in an amount sufficient to provide a dry particulate solid mixture, preferably a powder. 8. A method according to claim 7, wherein the paste comprises at least about 40 by weight of succinyl peroxide, the balance being water, and preferably about 70% by weight of succinyl peroxide and about 30% by weight of water. 9. A method according to claim 7 or claim 8, wherein from about 40% to about 95% by weight of dehydrating agent is employed based on the total weight of dehydrating agent and paste, and preferably from about 45% to about 800fro by weight of dehydrating agent. 10. A method according to any one of claims 7 to 9, wherein the dehydrating agent is anhydrous sodium or magnesium sulphate or a partial hydrate thereof, preferably magnesium sulphate monohydrate or dihydrate.

Inventors: BROCKLEHURST, PETER, FERGUSON, ANGUS SCOTT
Applicants: STERWIN AG.
Application year: 1982
Main classification: C07C179
IPC codes: A01N37, C07C409, C07C407, A61L9, A01N25