METHOD OF TREATING A SUBSTRATE WITH A MULTIPLICITY OF SOLID PARTICLES

Abstract

A method of treating a substrate comprising a first step of agitating a composition comprising solid particles comprising biodegradable polyester having a number-average molecular weight of from 10,000 Daltons to 500,000 Daltons, said solid particles having a size of from 0.1 mm to 100 mm; a liquid medium; and the substrate, and a second step comprising separating the solid particles from the substrate.

Claims

1. A method of treating a substrate comprising a first step of agitating a composition comprising solid particles comprising biodegradable polyester having a number-average molecular weight of from 10,000 Daltons to 500,000 Daltons, said solid particles having a size of from 0.1 mm to 100 mm; a liquid medium; and the substrate, and a second step comprising separating the solid particles from the substrate.

2. A method according to claim 1 wherein solid particles separated in said second step are re-used in a further method comprising said first and second steps defined in claim 1.

3. A method according to claim 2 wherein the solid particles are re-used at least 10 times.

4. A method according to any of the preceding claims wherein the biodegradable polyester has a number-average molecular weight of from 30,000 Daltons to 500,000 Daltons.

5. A method according to any one of the preceding claims wherein the biodegradable polyester has a solidus of from 160° C. and 250° C.

6. A method according to any one of the preceding claims wherein the biodegradable polyester is obtained by polymerizing one or more monomers at least one of which is selected from lactic acid, lactide, glycolic acid, hydroxy butyric acid, 3-hydroxy propionic acid, hydroxy valeric acid and caprolactone, including salts thereof.

7. A method according to claim 6 wherein the biodegradable polyester is obtained by polymerizing one or more monomers, at least one of which is lactic acid or lactide including salts thereof.

8. A method according to any one of the preceding claims wherein the biodegradable polyester is obtained by ring opening polymerisation of one or more monomers, at least one of which is a cyclic ester.

9. A method according to claim 8 wherein the biodegradable polyester is obtained by ring opening polymerisation of one or more monomers, at least one of which is lactide.

10. A method according to any one of the preceding claims wherein the biodegradable polyester is completely or partially in the amorphous state.

11. A method according to any one of the preceding claims wherein the solid particles comprise the biodegradable polyester and no filler.

12. A method according to any one of the preceding claims wherein the substrate is pliable.

13. A method according to any one of the preceding claims wherein the substrate is or comprises a textile, a fibre, or a yarn.

14. A method according to any one of the preceding claims wherein the substrate comprises an animal skin.

15. A method according to any one of the preceding claims wherein the liquid medium comprises water.

16. A method according to any one of the preceding claims wherein the liquid medium has a pH in the range of from pH 3 to pH 13.

17. A method according to any preceding claims wherein the composition comprises a surfactant and/or an enzyme.

18. A method according to any one of the preceding claims wherein the liquid medium has a temperature of from 5° C. to 70° C. during the first step.

19. A method according to any of the preceding claims wherein treating is or comprises cleaning.

20. A method according to claim 19 wherein the substrate is soiled prior to the first step.

21. A method according to any one of the preceding claims wherein at least some of the solid particles have a shape which is spheroidal or ellipsoidal.

22. A method according to any one of the preceding claims wherein the solid particles comprise no releasable material.

23. A method according to any one of the preceding claims wherein all of the solid particles present comprise said biodegradable polyester.

24. A method according to any one of the preceding claims wherein the biodegradable polyester is insoluble in water.

25. A method according to any one of the preceding claims which comprises the additional step of determining the number-average molecular weight of the biodegradable polyester in the solid particles and removing and replacing the solid particles with fresh solid particles when the number-average molecular weight falls below 10,000 Daltons

Description

EXAMPLES

[0114] Materials

[0115] Polylactide material was obtained from Natureworks LLC under the tradename Ingeo 2003D.

[0116] The Polylactide material was hot melt extruded using a twin screw extruder and underwater cut into particles having an average size of 4 mm for one batch (hereinafter PLA-1) and 6.5 mm for another batch (hereinafter PLA-2). The size being the longest linear dimension. The polylactide within PLA-1 had a number average molecular weight of approximately 56,000 Daltons. The polylactide within PLA-2 had a number average molecular weight of approximately 73,000 Daltons. The molecular weights were determined by GPC using at 40° C. in tetrahydrofuran.

[0117] Nylon 6 was twin screw extruded with barium sulphate in a weight ratio of 55 wt % Nylon to 45 wt % barium sulfate and underwater cut into particles having an average size of 4 mm for one batch (Nylon-1) and 6 mm for another batch (Nylon-2). The size again being the longest linear dimension.

[0118] The detergents used in the treating of the substrates were Tide HE which is manufactured by Procter and Gamble and Pack 1 which is a detergent available from Xeros.

[0119] Pack 2 is an oxidizing stain remover which is supplied by Xeros.

[0120] The substrate used in some of the treatments were EMPA 108 stain sheets which were obtained from Swissatest, these sheets had dimensions of approximately 12 cm by 12 cm and comprised a mixture of standard stains to be cleaned.

[0121] In order to add realistic levels of soiling into some treatments SBL2004 sebum sheets obtained from WFK were used. These add soil into the treatment step in a realistic way.

CLEANING EXAMPLES

Cleaning Example 1

[0122] A Xeros washing machine having a loading capacity of 25 Kg of dry substrate as described in PCT patent publication WO 2011/098815 was used to treat (clean) the substrates in accordance with the present invention. The Xeros washing machine was loaded with a 20 Kg load comprising a British Standard ballast comprising a mixture of towels (EMPA 351), sheets (EMPA352) and pillow cases (EMPA353). In addition, 6 EMPA 108 stain sheets, 10 sebum sheets both as described in the materials section were loaded into the Xeros washing machine.

[0123] Pack 1 detergent (250 g) as described in the materials section was used for each wash load to assist the cleaning.

[0124] Solid particles (25 kgs) in the form of PLA-1 as described in the materials section were used.

[0125] Water was used as the liquid medium.

[0126] The treatment was cleaning which was performed for a period of 1 hour at a temperature of 20° C. The Xeros washing machine agitated (tumbled) the composition comprising the solid particles, the water, the substrate (EMPA 108 stain sheets) and the detergent (Pack 1).

[0127] The Xeros washing machine automatically separated the solid particles from the substrate towards the end of the 1 hour period and moved the solid particles to a separate sump.

[0128] The washing machine contents were then unloaded. The EMPA 108 stain sheets were removed from the washload, ironed using a trouser press and left overnight to dry and acclimatise.

[0129] Test Methodology

[0130] EMPA108 stain sheets obtained from Cleaning Example 1 were measured using a spectrophotometer from Konica Minolta with model number CM3600A. Each stain is measured 4×, twice on each side and an average Y value is recorded for each stain type. There were five stain types on each EMPA stain sheet. The “Sum of Y” value is then taken as the sum of each of the five average Y values for each stain.

Comparative Cleaning Example 1

[0131] Comparative Cleaning Example 1 was performed in exactly the same way as Cleaning Example 1 except that the solid particles were replaced with 25 Kg of Nylon-1 as described in the materials section.

[0132] Results

[0133] The Sum of Y values for Cleaning Example 1 and Comparative Cleaning Example 1 were as indicated below in Table 1.

TABLE-US-00001 TABLE 1 Solid Particle Sum Example type of Y Cleaning Example 1 PLA - 1 306 Comparative Cleaning Nylon - 1 301 Example 1

[0134] In this set of results a higher Sum of Y value indicates a better effectiveness of the cleaning. These results showed that, within the error margins of experimentation, the cleaning performance of the present invention is at least as good if not better than the known art which uses non-biodegradable polymers such as Nylon.

[0135] Biodegradability Testing

[0136] Solid particles (PLA-1) as described in the materials section were submersed in slightly salty water at a temperature 20° C. for a period of 6 months. After this submersion the number average molecular weight of the polymer in the solid particles was remeasured and found to be 49,000 Daltons. Thus, in the 6 months' time period the molecular weight had reduced by approximately 12%. Clearly, seawater is actively biodegrading the polyester present in the solid particles.

[0137] In contrast, Nylon-1 particles are known to be substantially invulnerable to biodegradation.

Cleaning Example 2

[0138] A Xeros washing machine having a loading capacity of 8 Kg of dry substrate as described in PCT patent publication WO2018/172725 was used to treat (clean) the substrates in accordance with the present invention. The Xeros washing machine was loaded with a 5.5 Kg load comprising a real-world substrates comprising a mixture of t-shirts, long sleeved shirts, polo shirts, jumpers, hoodies, children's clothing and jeans. In addition, 1 sebum sheet as described in the materials section was loaded into the Xeros washing machine.

[0139] Tide HE (22.5 g) as described in the materials section was used for each wash load to assist the cleaning.

[0140] Solid particles (5 kgs) in the form of PLA-2 as described in the materials section were used.

[0141] Water was used as the liquid medium.

[0142] The treatment was cleaning which was performed for a period of 1 hour at a temperature of 20° C. The Xeros washing machine agitated (tumbled) the composition comprising the solid particles, the water, the substrates and the detergent (Tide HE).

[0143] The Xeros washing machine automatically separated the solid particles from the substrate towards the end of the 1 hour period and moved the solid particles to a storage compartment in a rear portion of the drum.

[0144] The washing machine contents were then unloaded. Whilst unloading the substrates any solid particles remaining in or on the substrates were separated by hand and counted. The total number of remaining solid particles was then calculated.

[0145] Cleaning Example 2 was repeated a further 4 times (to a total of 5 times) and an average value for the total number of remaining solid particles was then calculated.

Comparative Cleaning Example 2

[0146] Comparative Cleaning Example 2 was performed in exactly the same way as Cleaning Example 2 (including the 4 repeats thereof) except that the solid particles used were Nylon-2,

[0147] Results

[0148] The average total numbers of remaining solid particles were as indicated in Table 2.

TABLE-US-00002 TABLE 2 Solid Particle Average remaining Example type total solid particles Cleaning Example 2 PLA - 2 33 Comparative Cleaning Nylon - 2 82 Example 2

[0149] A higher average number of remaining total solid particles is undesirable as such particles must be manually removed. Surprisingly, the solid particles used in the present invention resulted in markedly superior automatic separation in the Xeros washing machine.

[0150] Re-Usability

Cleaning Example 3

[0151] A Xeros washing machine having a loading capacity of 25 Kg of dry substrate as described in PCT patent publication WO 2011/098815 was used to treat (clean) the substrates in accordance with the present invention. The Xeros washing machine was loaded with a 20 Kg load comprising substrates comprising a mixture of towels (EMPA 351), sheets (EMPA352) and pillowcases (EMPA353). In addition, 4 sebum sheets both as described in the materials section were loaded into the Xeros washing machine.

[0152] Pack 1 (250 g) and Pack 2 (250 g) as described in the materials section were used for each wash load to assist the cleaning.

[0153] Solid particles (25 kgs) in the form of PLA-1 as described in the materials section were used.

[0154] Water was used as the liquid medium.

[0155] The treatment was cleaning which was performed for a period of 1 hour and 10 minutes at a temperature of 40° C. The Xeros washing machine agitated (tumbled) the composition comprising the solid particles, the water, the substrate and the detergent (Packs 1 and 2).

[0156] The Xeros washing machine automatically separated the solid particles from the substrate towards the end of the 1 hour and 10 minutes period and moved the solid particles to a separate sump.

[0157] The washing machine contents were not unloaded between repeat cleaning cycles.

[0158] The cleaning cycles were repeated to a total of 250 and 500 cycles. The same solid particles and load were used for every repeat but fresh water and detergent were used for each separate cleaning cycle.

[0159] At 250 and 500 cycles the number averaged molecular weight of the polyester in PLA-1 solid particles was re-measured.

[0160] Results

[0161] The molecular weights and the visual appearance of the solid particles at 0, 250 and 500 wash cycles was as tabulated in Table 3.

TABLE-US-00003 TABLE 3 Cleaning Solid Particle Molecular weight Visual Example 3 type (Mn) appearance  0 cycles PLA - 1 56,000 Solid particles with no visible softening or disintegration. 250 cycles PLA - 1 53,400 Solid particles with no visible softening or disintegration. 500 cycles PLA - 1 52,700 Solid particles with no visible softening or disintegration.

[0162] In Table 3 it was clearly seen that the biodegradable polyester in the solid particles was surprising capable of providing cleaning performance over at least 500 repeat cycles even at an elevated temperature of 40° C. The molecular weight and visual appearance results both confirm that many hundreds of repeat cycles are perfectly possible. What was additionally surprising was that this particular example used substantially high levels of detergent and stain remover.

[0163] The present inventors have also performed experiments similar to Cleaning Example 3 which differ in that the temperature during the wash cycle was even higher at 60° C. and using even more aggressive cleaning chemistry including cleaning agents such as oxalic acid, sodium hypochlorite, sodium hydroxide, sodium metabisulfite, Rexasol plus (a non-ionic detergent) and Xeros Pack 1. The results of this experiment also showed that solid particles comprising PLA-1 were capable of cleaning effectively for at least 50 re-use cycles.