Activation of peroxygen bleach

Abstract

A peracid bleaching species is formed in situ in aqueous wash liquor by reaction of a peroxygen bleach precursor, such as perborate or percarbonate, and a bleach activator. The bleach activator is an acetylated ethylene diamine, that comprises at least 25% triacetyl ethylene diamine. The peracid is formed more rapidly even at low temperatures (F2) compared to use of conventional pure tetracetyl ethylene diamine (F1) and better disinfectant properties result.

Claims

1. A process for producing a peracetic acid solution comprising reacting in aqueous solution hydrogen peroxide or a precursor thereof and an N-acetylated ethylene diamine material to perhydrolyse the amide bond, characterized in that the N-acetylated ethylene diamine material comprises at least 50% by weight N, N, N-triacetylethylene diamine (TriAED), at least 5% by weight N,N,N,N-tetraacetylethylene diamine (TAED) and N,N-diacetylethylene diamine (DAED), in an amount less than 20% by weight.

2. The process according to claim 1 wherein the N-acetylated ethylene diamine material comprises less than 20% by weight TAED.

3. The process according to claim 1 wherein the N-acetylated ethylene diamine material comprises N,N-diacetylethylene diamine (DAED), in an amount less than 10% by weight.

4. The process according to claim 1 comprising the preliminary step of providing a solution of the hydrogen peroxide or precursor thereof by adding to water a particulate detergent composition containing an inorganic persalt and the N-acetylated ethylene diamine material.

5. The process according to claim 4 wherein the inorganic persalt and N-acetylated ethylene diamine material are present in the particulate detergent in separate particles.

6. The process according to claim 4 wherein the inorganic persalt is selected from percarbonates and perborates of alkali metals.

7. The process according to claim 4, wherein the particulate detergent composition further comprises surfactant, builder, sequestrant, enzymes, additional bleach activator and/or dyes.

8. The process according to claim 4 wherein the temperature of the water to which the detergent composition is added is no higher than 40 C., and peracetic acid solution is subsequently used to clean a substrate in a cleaning step, followed by a rinsing step in which the spent peracetic acid solution is rinsed from the substrate.

9. The process according to claim 4, wherein the temperature of the water to which the detergent composition is added is no higher than 40 C.

10. A particulate detergent composition comprising peroxygen bleach precursor particles and N-acetylated ethylene diamine material particles, characterized in that the said N-acetylated ethylene diamine material particles comprises at least 50% by weight N,N,N-triacetylethylene diamine, at least 5% by weight tetra-acetylethylene diamine and N,N-diacetylethylene diamine in an amount less than 20% by weight.

11. The composition according to claim 10 wherein both sets of particles have average diameters in the range 200-800 m.

12. The composition according to claim 10 wherein the N-acetylated ethylene diamine material particles are present in an amount in the range 1 to 20% by weight, of the total weight of composition, the peroxygen bleach precursor is present in an amount in the range 2 to 50% by weight, of the total weight of composition, and wherein the weight ratio of peroxygen bleach precursor to acetylated ethylene diamine material in the composition is in the range 1 to 5.

13. The composition according to claim 10 further comprising a hydrophobic bleach activator.

14. The composition according to claim 10 further comprising surfactant, builder, sequestrant, enzymes, additional bleach activator and/or dyes.

15. The composition according to claim 10 wherein the particles containing the N-acetylated ethylene diamine material additionally contain a binder.

Description

(1) The accompanying figures relate to the following:

(2) FIGS. 1 and 2 shows the rate of peracid release from an acetylation product mixtures comprising a high proportion of TriAED, as compared to a commercial TAED granule;

(3) FIG. 3 shows the biocidal efficiency of the solutions.

(4) The invention is illustrated further by the accompanying examples.

EXAMPLES

Example 1

(5) Ethylene diamine is acetylated to form DAED by reaction with acetic acid. The DAED is further reacted by acetylation using acetyl anhydride. The product mixture is predominately TriAED and TAED with residual amounts of unconverted DAED. TAED is removed from the reaction mixture by cooling, as a solid by filtration. The TriAED enriched reaction mixture is evaporated to dryness to remove volatiles and then the residue is further evaporated to yield an acetylated ethylene diamine mixture as product as distillate with the high boiling point by-products remaining as residue. By controlling the feed composition of the liquor entering this evaporation process, the proportion of TriAED in the acetylated diamine product mixture is controlled.

(6) The feed stream to the plant comprises the following levels of materials

(7) TABLE-US-00001 DAED <4% TriAED <20% TAED <4% Acetic Anhydride <80% Acetic Acid <30% Polymeric Amide <17%

(8) Composition of product stream from the plant is kept within the range

(9) TABLE-US-00002 DAED <15% TriAED <90% TAED <30%
Formulation of Acetylated Ethylene Diamine

(10) The product of the plant produced as indicated above was combined with 10% PEG 8000 binder and 1% glycerol as lubricant in an extruder with a cooled mixing zone controlled at a temperature around 43 C. and fed to an extrusion zone controlled at a temperature below 35 C. The batch (300 g) processing time is around 4 minutes. The extruder forms particle sizes having at least 95% in the range 400-1600 m (by sieve analysis).

(11) Testing of Peracetic Acid Release Rates and Biocidal Testing

(12) Testing of peracetic acid release rate is carried out according to the standard test method described above.

(13) For the biocidal tests, the capability of the activated liquor to kill microorganisms commonly contaminating fabrics and washing machines is determined.

(14) A test method based on BS EN1276 was used to determine the bactericidal efficacy of test solutions against:

(15) Escherichia coli ATCC 10536

(16) Pseudomonas aeruginosa ATCC 15442

(17) Staphylococcus aureus ATCC 6528

(18) Micro-organisms were cultured at 37 C.

(19) The following test formulations were added to 1 liter of sterile hard water, prepared for use in the test method based on BS:EN1276, at 20 C. Test solutions were stirred with an overhead paddle stirrer at 75 rpm at 20 C., F1 and F2 for 5 mins, prior to samples being taken for efficacy testing. The base used was Diao Washing Detergent Base (Nice).

(20) Test formulations F1 and F2 were calculated to deliver a theoretical maximum release of 80 ppm peracetic acid. Tri AED was delivered in the form of an extrudate containing 60.53% Tri AED, 12.99% TAED, residual DAED (7%) with 13% PEG binder, and TAED was delivered as Mykon ATC (trade mark) a commercially available particulate presentation of TAED combining CMC binder and a sequestrant.
0.125 g TAED(8.75%)+0.248 g PCS(17.35%)+1.058 g Diao base (73.90%)F1
0.25 g Tri AED extrudate*(16.07%)+0.248 g PCS(15.94%)+1.058 g Diao base(67.99%)F2

(21) *Tri AED extrudate contained60.53% Tri AED, 12.99% TAED

(22) Bacterial test suspensions were prepared according to the protocol based on the BS EN1276 test protocol. 8 mls of each test solution were inoculated into a mixture of 1 ml bacterial test suspension and 1 ml Bovine Serum Albumin (0.3 g/l BSA for simulated clean conditions) Contact time for test formulations F1 and F2 was 10 mins. Contact temperature was 20 C. After this time 1 ml was taken and added to neutraliser liquid for 5 mins. Samples were diluted down and plated out using Tryptone Soya Agar maintained at 45 C.

(23) Enumeration of bacterial colony forming units and calculation of bacterial log reduction was carried out based on test protocol.

(24) Peracid Release Results

(25) In Table 1 are results obtained for peracid release monitoring of all four of the test formulations. These are also shown graphically in FIG. 1 (ppm PAR) and FIG. 2 (% theoretical max).

(26) TABLE-US-00003 TABLE 1 Peracid Release Time (mins) F1 (ppm) F1 (% th. max) F2 (ppm) F2 (% th. max) 0 0 0 0 0 2 10 12.0 42 50 5 38 45.8 78 92.8 10 72 86.7 87 100 15 72 86.7 87 100 20 68 82.5 87 100 30 76 91.6 87 100

(27) Table 2 shows the results obtained for bactericidal efficacy:

(28) TABLE-US-00004 Test Log Reduction Log Reduction Log Reduction Formulation E.coli St. aureus Ps. aer F1 3.73 2.29 1.90 F2 6.06 4.97 3.65

(29) These are illustrated also in FIG. 3.

CONCLUSION

(30) The aim of the project was to establish the biocidal benefits of using Tri AED, at low temperature and low agitation, conditions indicative of hand wash/soak use, compared to TAED,

(31) Tri AED and TAED (Mykon ATC) were included in the test formulations at levels to deliver a theoretical maximum release of 80 ppm and 40 ppm of peracetic acid. This would allow an equal comparison and also show if faster release contributed to the benefits of the activator.

(32) The results show that the Tri AED releases peracetic acid at a much faster rate, at low agitation and temperature, compared to Mykon ATC. Tri AED reaches 92% release in 5 minutes compared to 45% for TAED. Thus the Tri AED test solution demonstrates higher levels of bactericidal activity after 5 mins generation time and 10 mins contact time (F1 and F2).

(33) The results overall do support the use of a Tri AED product to deliver a rapid hygienic effect under low temperature, hand wash/soak conditions.