Cleaning method

Abstract

The invention provides a method and formulation for cleaning a soiled substrate, the method comprising the treatment of the moistened substrate with a formulation comprising a multiplicity of polymeric particles, wherein the formulation is free of organic solvents. Preferably, the substrate is wetted so as to achieve a substrate to water ratio of between 1:0.1 to 1:5 w/w. Optionally, the formulation additionally comprises at least one cleaning material and, in this embodiment, it is preferred that the polymeric particles are coated with the at least one cleaning material. Preferably, the cleaning material comprises a surfactant, which most preferably has detergent properties. Most preferably, the substrate comprises a textile fiber. Typically, the polymeric particles comprise particles of nylon, most preferably in the form of nylon chips. The results obtained are very much in line with those observed when carrying out conventional dry cleaning processes and the method provides the significant advantage that the use of solvents, with all the attendant drawbacks in terms of cost and environmental considerations, can be avoided.

Claims

1. A method for cleaning a soiled substrate, said method comprising treating the soiled substrate with water to provide a premoistened soiled substrate and treating the premoistened soiled substrate with a formulation comprising a multiplicity of polymeric particles, wherein said polymeric particles contact the substrate during the cleaning process, wherein said formulation is free of organic solvents, wherein said polymeric particles comprise polyamide, polyesters or polyurethanes, or their copolymers, wherein said polymeric particles are re-used in further cleaning procedures according to the method, and wherein the soiled substrate comprises a textile fiber or leather.

2. The method as claimed in claim 1, wherein said textile fiber comprises cotton, nylon 6,6 or a polyester.

3. The method as claimed in claim 1, wherein said soiled substrate is wetted by contact with mains or tap water.

4. The method as claimed in claim 3, wherein said soiled substrate is wetted so as to achieve a substrate to water ratio of between 1:0.1 to 1:5 w/w.

5. The method as claimed in claim 1, wherein said formulation comprises at least one cleaning material selected from anionic, cationic and non-ionic surfactants.

6. The method as claimed in claim 5, wherein said at least one cleaning material is mixed with said polymeric particles.

7. The method as claimed in claim 5, wherein each of said polymeric particles is coated with said at least one cleaning material.

8. The method as claimed in claim 7, wherein said polymeric particles are coated with said cleaning material by mixing with 0.5%-10% of the material.

9. The method as claimed in claim 7, wherein said polymeric particles are coated with said cleaning material by mixing with said material and the resulting mixture is held at a temperature of between 30 C. and 70 C.

10. The method as claimed in claim 9, wherein said polymeric particles are coated with said cleaning material by mixing with said material at said temperature for a time of between 15 and 60 minutes.

11. The method as claimed in claim 1, wherein said particles to textile fiber is in a ratio of from 30:1 to 1:1 w/w.

12. The method as claimed in claim 1, wherein said polyamide particles comprise particles of nylon.

13. The method as claimed in claim 12, wherein said particles of nylon comprise nylon chips.

14. The method as claimed in claim 12, wherein said nylon comprises Nylon 6 or Nylon 6,6.

15. The method as claimed in claim 1, wherein said particles are in the shape of cylinders, spheres or cubes.

16. The method as claimed in claim 15, wherein said cylindrically shaped particles have an average particle diameter in the region of from 1.5 mm to 6.0 mm.

17. The method as claimed in claim 16, wherein the length of said cylindrical particles is in the range of from 2.0 mm to 6.0 mm.

18. The method as claimed in claim 1, wherein said particles have an average weight in the region of from 20 mg to 50 mg.

19. The method as claimed in claim 1, wherein said particles are in intimate contact with the textile fiber during the cleaning process.

20. The method as claimed in claim 1, which comprises a continuous process or a batchwise process.

21. The method as claimed in claim 1, wherein said method is carried out in an apparatus or container which encourages Newtonian Flow.

22. The method as claimed in claim 21, wherein said process is carried out in a fluidized bed.

23. The method as claimed in claim 1, wherein said treatment is carried out at a temperature of between 30 C. and 90 C.

24. The method as claimed in claim 23, wherein said treatment is carried out for a duration of between 20 minutes and 1 hour.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows the reduction in stain of pre-soiled mercerized cotton fabric after cleaning according to the method of Example 2.

(2) FIG. 2 shows the reduction in numbers of soil particles (10 magnification) in pre-soiled mercerized cotton fabric after cleaning according to the method of Example 3.

(3) FIG. 3 shows the change in colour strength illustrating extent of stain removal from soiled cotton fabric after cleaning according to the method of Example 5.

(4) FIG. 4 shows the change in colour strength illustrating extent of removal of coloured materials from soiled cotton fabric after scouring according to the method of Example 7.

DESCRIPTION OF THE INVENTION

(5) In the method according to the first aspect of the invention, which is known as the interstitial method of cleaning or scouring, the ratio of beads to substrate is based on a nominal liquor ratio in terms of a conventional dry cleaning system, with the preferred ratio being in the range of from 30:1 to 1:1 w/w, preferably in the region of from 20:1 to 10:1 w/w, with particularly favourable results being achieved with a ratio of around 15:1 w/w. Thus, for example, for the cleaning of 5 g of fabric, 75 g of polymeric particles, optionally coated with surfactant, would be employed.

(6) As previously noted, the method of the invention finds particular application in the cleaning of textile fibres. The conditions employed in such a cleaning system are very much in line with those which apply to the conventional dry cleaning of textile fibres and, as a consequence, are generally determined by the nature of the fabric and the degree of soiling. Thus, typical procedures and conditions are in accordance with those which are well known to those skilled in the art, with fabrics generally being treated according to the method of the invention at, for example, temperatures of between 30 and 90 C. for a duration of between 20 minutes and 1 hour, then being rinsed in water and dried.

(7) In the embodiment of the invention wherein the formulation comprises at least one cleaning material, it is preferred that the polymeric particles should be coated with the at least one surfactant, in order to achieve a more level distribution of the said surfactant on the particles and, consequently, on the substrate, as the particles contact the substrate during the cleaning process. Typically, this coating process requires that the polymeric particles should be mixed with 0.5%-10%, preferably 1%-5%, most preferably around 2% of the at least one surfactant, and the resulting mixture held at a temperature of between 30 and 70 C., preferably 40 and 60 C., most preferably in the region of 50 C., for a time of between 15 and 60 minutes, preferably between 20 and 40 minutes, with the most satisfactory results being obtained when the treatment is carried out for approximately 30 minutes.

(8) The results obtained are very much in line with those observed when carrying out conventional dry cleaning procedures with textile fabrics. The extent of cleaning and stain removal achieved with fabrics treated by the method of the invention is seen to be very good, with particularly outstanding results being achieved in respect of hydrophobic stains and aqueous stains and soiling, which are often difficult to remove. The method also finds application in wash-off procedures applied to textile fibres subsequent to dyeing processes, and in scouring processes which are used in textile processing for the removal of dirt, sweat, machine oils and other contaminants which may be present following processes such as spinning and weaving. No problems are observed with polymer particles adhering to the fibres at the conclusion of the cleaning process. Furthermore, of course, as previously observed, the attendant drawbacks associated with the use of solvents in conventional dry cleaning processes, in terms of both cost and environmental considerations, are avoided, whilst the volumes of water required are significantly lower than those associated with the use of conventional washing procedures.

(9) Additionally, it has been demonstrated that re-utilisation of the polymer particles is possible, and that particles can be satisfactorily re-used in the cleaning procedure, although some deterioration in performance is generally observed following three uses of the particles. When re-using particles, optimum results are achieved when using particles coated with the at least one coating material which are then re-coated prior to re-use.

(10) The method of the invention will now be exemplified, though without in any way limiting the scope of the invention, by reference to the following examples:

EXAMPLES

Example 1

(11) The polymer particles comprised cylindrical nylon chips comprising Nylon 6,6 polymer having a molecular weight in the region of 15000-16000 Daltons, with average dimensions of 4 mm in length and 2-3 mm in diameter, and an average particle weight of 30-40 mg.

(12) The fabric to be cleaned comprised soiled and stained Nylon 6,6 fibres, and the wetted dyed fabric was entered into the dry cleaning bath at 40 C. and the temperature was maintained at 40 C. for 10 minutes, then increased to 70 C. at a rate of 2 C. per minute, and then maintained at 70 C. for 20 minutes, after which time the fabric was removed, rinsed and dried. Complete removal of the soiling and staining was achieved.

Example 2

(13) The fabric to be cleaned comprised a soiled cloth of mercerised cotton stained with coffee in an aqueous transport medium, the cloth having an air dry mass of 5 g. This pre-soiled fabric sample was placed in a 2 liter sealed container with 75 g (air dry mass) of polymer particles comprising cylindrical chips of Nylon 6,6 polymer, with average dimensions of 4 mm in length and 4 mm in diameter. The pre-soiled fabric sample was wetted with tap water before commencement of cleaning to give a substrate to water ratio of 1:1. The sealed container was tumbled/rotated for 30 minutes to a maximum of 70 C. with a cooling stage at the end of the cycle. Once cleaned, the fabric was removed from the sealed container and dried flat. The colour change to the stained area after cleaning was measured spectrophotometrically and is illustrated in FIG. 1, from which it is apparent that the degree of staining was very significantly reduced following the cleaning process.

Example 3

(14) The fabric to be cleaned comprised a soiled cloth of mercerised cotton stained with city street dirt in an aqueous transport medium, the cloth having an air dry mass of 5 g. This pre soiled fabric sample is placed in a 2 liter sealed container with 75 g (air dry mass) of polymer particles comprising cylindrical chips of Nylon 6,6 polymer, with average dimensions of 4 mm in length and 4 mm in diameter. The pre-soiled fabric sample was wetted with tap water before commencement of cleaning to give a substrate to water ratio of 1:2. The sealed container was tumbled/rotated for 30 minutes to a maximum of 70 C. with a cooling stage at the end of the cycle. Once cleaned, the fabric was removed from the sealed container and dried flat. The degree of removal of particulate stain after cleaning was determined by microscopy and is illustrated in FIG. 2, from which it can be seen that a significant reduction in numbers of dirt particles was observed after the cleaning process had taken place.

Example 4

(15) The fabrics to be cleaned comprised soiled cloths (cotton and polyester stained with coffee, soil, boot polish, ball point pen, lipstick, tomato ketchup and grass) with an air dry mass of 5 g. Each pre-soiled fabric sample was placed in a 2 liter sealed container with 75 g (air dry mass) of the polymer particles (cylindrical nylon chips comprising nylon 6,6 polymer, with average dimensions of 4 mm in length and 4 mm in diameter). Each pre-soiled fabric sample was wetted with mains or tap water before cleaning commenced to give a substrate to water ratio of 1:1. The sealed container was tumbled/rotated for 30 minutes at a maximum temperature of 70 C. with a cooling stage at the end of the cycle. Once cleaned, the fabric was then removed from the sealed container and dried flat. In each case, the colour change to the stained area can be seen from the change in colour difference using E* and CIEDE2000 (1:1), and the colour difference measurements for the Lab* values are also included in Tables 1 and 2.

(16) TABLE-US-00001 TABLE 1 Colour difference for stain removal by the interstitial cleaning method for cotton fabric using the method of Example 4 Sample DL* Da* Db* E* CIE2000 DE Soil 21.48 0.57 0.20 21.49 16.59 Coffee 7.53 2.86 7.45 10.97 6.99 Boot polish 7.41 0.09 0.32 7.42 5.96 Ball point pen 4.86 1.93 7.82 9.41 8.05 Lipstick 21.54 19.34 10.07 30.65 19.92 Tomato ketchup 3.03 2.32 8.63 9.44 6.26 Grass 4.17 4.10 4.87 7.60 5.30

(17) TABLE-US-00002 TABLE 2 Colour difference for stain removal by the interstitial cleaning method for polyester fabric using the method of Example 4 Sample DL* Da* Db* E* CIE2000 DE Soil 16.15 0.63 0.26 16.16 11.78 Coffee 13.90 6.53 12.30 19.68 13.08 Boot polish 2.28 0.16 0.15 2.29 1.84 Ball point pen 17.66 0.66 1.31 17.72 14.06 Lipstick 23.79 15.45 6.92 29.20 21.25 Tomato ketchup 7.77 2.56 21.66 23.16 12.68 Grass 0.74 1.20 1.17 1.83 1.92

Example 5

(18) The fabric to be cleaned comprised a soiled cloth (cotton stained with city street dirt in an aqueous transport medium) with an air dry mass of 5 g. This pre soiled fabric sample was placed in a 2 liter sealed container with 75 g (air dry mass) of the polymer particles (cylindrical nylon chips comprising nylon 6,6 polymer, with average dimensions of 4 mm in length and 4 mm in diameter). The pre-soiled fabric sample was wetted with mains or tap water before cleaning commenced to give a substrate to water ratio of 1:2. The sealed container was tumbled/rotated for 30 minutes to a maximum temperature of 70 C. with a cooling stage at the end of the cycle. Once cleaned, the fabric was then removed from the sealed container and dried flat. The amount of removal was measured in the change in colour strength values between the fabric before and after cleaning, as shown by the change in K/S values seen in FIG. 3.

Example 6

(19) The fabric to be cleaned comprised a soiled cloth (cotton stained with boot polish, soil, coffee and tomato ketchup) with an air dry mass of 1 kg. This pre-soiled fabric sample was placed in a sealed container with 15 kg (air dry mass) of the polymer particles (cylindrical nylon chips comprising nylon 6,6 polymer, with average dimensions of 4 mm in length and 4 mm in diameter). The pre-soiled fabric sample was wetted with mains or tap water before cleaning commenced to give a substrate to water ratio of 1:0.2. The sealed container was tumbled/rotated for 30 minutes to a maximum temperature of 70 C. with a cooling stage at the end of the cycle. Once cleaned, the fabric was then removed from the sealed container and dried. In each case, the colour change to the stained area can be seen from the change in colour difference using E* and CIEDE2000 (1:1) colour difference measurements, as shown in Table 3.

(20) TABLE-US-00003 TABLE 3 Colour difference for stain removal by the interstitial cleaning method for cotton fabric using the method of Example 6 Colour difference. CIELAB CIE2000 Fabric samples DE DE (1:1) Untreated boot polish stain to 9.7216 7.8725 Cleaned boot polish stain Untreated dirt stain to 45.3258 45.0107 Cleaned dirt stain Untreated ketchup stain to 14.3544 9.2786 Cleaned ketchup stain Untreated coffee stain to 5.9278 4.0275 Cleaned coffee stain

Example 7

(21) The fabric to be scoured comprised a greige cotton cloth with an air dry mass of 5 g. This greige fabric sample was placed in a 2 liter sealed container with 75 g (air dry mass) of the polymer particles (cylindrical nylon chips comprising nylon 6,6 polymer, with average dimensions of 4 mm in length and 4 mm in diameter). The greige fabric sample was wetted with mains or tap water before cleaning commenced to give a substrate to water ratio of 1:2. The sealed container was tumbled/rotated for 30 minutes to a maximum temperature of 70 C. with a cooling stage at the end of the cycle. Once cleaned the fabric was then removed from the sealed container and dried flat. The difference in colour between conventionally scoured fabric and the fabric cleaned using the novel process was assessed by the change in colour strength values between the fabrics shown by the change in K/S values seen in FIG. 4.