METHOD FOR CLEANING MEDICAL EQUIPMENT

Abstract

A method for cleaning medical equipment by scrubbing the equipment with an open-cell melamine-formaldehyde foam comprising an antibacterial active composition, and wherein the open-cell melamine-formaldehyde foam is prepared from a melamine-formaldehyde precondensate, wherein the molar ratio melamine to formaldehyde of the melamine-formaldehyde precondensate is smaller than 0.5.

Claims

1.-11. (canceled)

12. A method for cleaning medical equipment comprising scrubbing the equipment with a melamine-formaldehyde foam comprising an antibacterial active composition, wherein the melamine-formaldehyde foam is prepared from a melamine-formaldehyde precondensate, wherein the molar ratio melamine to formaldehyde of the melamine-formaldehyde precondensate is smaller than 0.5.

13. The method according to claim 12, wherein the melamine-formaldehyde foam has an open-cell structure having an open-cell content, when measured to DIN ISO 4590, of more than 95%.

14. The method according to claim 12, wherein the melamine-formaldehyde foam has a density in the range from 8 to 12 kg/m.sup.3.

15. The method according to claim 12, wherein the melamine-formaldehyde foam has an open-cell structure which is totally or partially filled with a solution or dispersion comprising isopropyl alcohol, chlorhexidine gluconate or povidone-iodine or mixtures thereof as antibacterial active composition.

16. The method according to claim 12, wherein the melamine-formaldehyde foam comprises from 0.1 to 10 wt.-% of the antibacterial active composition.

17. The method according to claim 12, wherein the melamine-formaldehyde precondensate is essentially free from sulfite-groups.

18. The method according to claim 12, wherein the molar ratio melamine to formaldehyde of the melamine-formaldehyde precondensate is in the range from 1:2.5 to 1:3.5.

19. The method according to claim 12, wherein the melamine-formaldehyde foam is prepared in the presence of a surfactant mixture comprising 50 to 90 wt.-% of at least one anionic surfactant and 10 to 50 wt.-% of at least one nonionic surfactant, wherein the weight percentages are each based on the total weight of the surfactant mixture.

20. The method according to claim 19, wherein the surfactant mixture comprises 50 to 90 wt. % of at least one alkanesulfonate and 10 to 50 wt.-% of at least one alkyl polyethylene glycol ether.

21. The method according to claim 12, wherein a catheter or endoscope is used as medical equipment.

22. The method according to claim 21, wherein a Central Venous Catheter (CVC) system port is used as medical equipment.

Description

EXAMPLES

[0040] Hereinafter, the present invention is described in more detail and specifically with reference to the Examples, which however are not intended to limit the present invention.

Test Procedure for Cleaning Test

[0041] A test soil based on hand cream and carbon black was prepared and applied to tiles with a doctor blade to yield a film height of 300 μm. The material was subsequently burned onto tiles in an oven at 160° C. for 10 minutes. Tiles prepared by the aforementioned method were cleaned with melamine formaldehyde sponges and the number of strokes needed to remove the soil from the surface was measured.

Ram Pressure Value [N]:

[0042] All stamps pressure value measurements for evaluation of the mechanical/elastic properties of the melamine/formaldehyde foams were carried out as follows: one cylindrical steel die with a diameter of 8 mm and a height of 10 cm was applied at right angles in a cylindrical foam sample having a diameter of 11 cm and a height of 5 cm is pressed, to the foam sample broke. Up to the tearing of the foam sample maximum force applied by the plunger (unit: N), in the following also referred to as ram pressure value, provides information about the quality of the foam mechanically/elastic (reported in table 1 in each case the measurements were performed parallel to the rise direction of the foam). The larger the punch pressure values are, the better the mechanical/elastic properties of the melamine/formaldehyde foams.

Materials Used:

Melamine-Formaldehyde Precondensates:

[0043] mf-1: The melamine-formaldehyde precondensate mf-1 was a spray-dried melamine-formaldehyde precondensate having an average molecular weight (number average) Mn of 350 g/mol, which had a molar ratio of melamine:formaldehyde of 1:3, which apart from melamine comprised no further thermoset-formers and apart from formaldehyde comprised no further aldehydes and which was sulfite group free. [0044] mf-2: The melamine-formaldehyde precondensate mf-2 was a spray-dried melamine-formaldehyde precondensate having an average molecular weight (number average) Mn of 370 g/mol, which had a molar ratio of melamine:formaldehyde of 1:3, which apart from melamine comprised no further thermoset-formers and apart from formaldehyde comprised no further aldehydes, and which had a sulfite group content of 2.3 wt.-%, based on the total weight of the melamine-formaldehyde precondensate. [0045] mf-3: The melamine-formaldehyde precondensate mf-3 was a spray-dried melamine-formaldehyde precondensate, which had a molar ratio of melamine:formaldehyde of 1:1.6, which apart from melamine comprised no further thermoset-formers and apart from formaldehyde comprised no further aldehydes and which was sulfite group free. [0046] sm-1: Surfactant mixture of 80 wt. % alkanesulfonate mixture and 20 wt.-% alkyl polyethylene glycol ether mixture. [0047] sm-2: Surfactant mixture of 80 wt. % of sodium salt of fatty alcohol polyglycol ether sulfate and 20 wt.-% alkyl polyethylene glycol ether mixture.

Example 1

[0048] 70 parts by weight of a spray-dried melamine/formaldehyde precondensate mf-1 was dissolved in 30 parts by weight of water. To this mixture was added 2.75 parts by weight of sodium formate, 3.1 parts by weight of formic acid, 1.5 parts by weight of the surfactant mixture sm-1 and 17.8 parts by weight a blowing agent mixture of 80 wt.-% of n-pentane and 20 wt.-% of isopentane. This mixture was stirred vigorously and then foamed in a mould of polypropylene by irradiation of microwave energy at 2.54 GHz. The foam was afterwards cured in an oven at 100° C. and annealed at 240° C.

Example 2

[0049] 70 parts by weight of a spray-dried melamine/formaldehyde precondensate mf-2 was dissolved in 30 parts by weight of water. To this mixture was added 2.75 parts by weight of sodium formate, 3.1 parts by weight of formic acid, 1.5 parts by weight of the surfactant mixture sm-1 and 17.8 parts by weight a blowing agent mixture of 80 wt.-% of n-pentane and 20 wt.-% of isopentane. This mixture was stirred vigorously and then foamed in a mould of polypropylene by irradiation of microwave energy at 2.54 GHz. The foam was afterwards cured in an oven at 100° C. and annealed at 240° C.

[0050] Tiles prepared by the above described test procedure for cleaning test were cleaned with melamine formaldehyde sponges prepared from resins with bisulfite (Example 2) and without bisulfite (Example 1). The sponges were soaked with isopropanol before cleaning, squeezed dry and subsequently the number of strokes needed to remove the soil from the surface was measured. Results are reported in Table 1.

[0051] With the foam according to Example 1 only a mean number of 5.7 strokes were needed compared to 8.7 strokes for the foam according to Example 2. Less strokes mean more effective cleaning.

TABLE-US-00001 TABLE 1 Example 1 Example 2 melamine-formaldehyde mf-1 (sulfite- mf-2 (sulfite group pre-condensate group free) 2.3 wt.-%) Run 1 7 10  Run 2 4 7 Run 3 6 9 Mean number of strokes 5.7 ± 1.5 8.7 ± 1.5

Comparative Examples C3 and C4

[0052] 70 parts by weight of a spray-dried melamine/formaldehyde precondensate mf-3 was dissolved in 30 parts by weight of water. To this mixture was added 2.75 parts by weight of sodium formate, 3.1 parts by weight of formic acid, 1.5 parts by weight of the surfactant mixture sm-2 and 17.8 parts by weight a blowing agent mixture of 80 wt.-% of n-pentane and 20 wt.-% of isopentane. To this blowing agent containing melamine/formaldehyde precondensate 0.1 wt.-% AgNO.sub.3, based on the precondensate, was added in case of Example C4. This mixture was stirred vigorously and then foamed in a mould of polypropylene by irradiation of microwave energy at 2.54 GHz. The foam was afterwards cured in an oven at 100° C. and annealed at 240° C.

Comparative Example C5

[0053] 70 parts by weight of a spray-dried melamine/formaldehyde precondensate mf-3 was dissolved in 30 parts by weight of water. To this mixture was added 2.75 parts by weight of sodium formate, 3.1 parts by weight of formic acid, 1.5 parts by weight of the surfactant mixture sm-1 and 17.8 parts by weight a blowing agent mixture of 80 wt.-% of n-pentane and 20 wt.-% of isopentane. This mixture was stirred vigorously and then foamed in a mould of polypropylene by irradiation of microwave energy at 2.54 GHz. The obtained foam was not stable and collapsed during curing.

Examples 6 and 7

[0054] 70 parts by weight of a spray-dried melamine/formaldehyde precondensate mf-1 was dissolved in 30 parts by weight of water. To this mixture was added 2.75 parts by weight of sodium formate, 3.1 parts by weight of formic acid, 1.5 parts by weight of the surfactant mixture sm-1 and 17.8 parts by weight a blowing agent mixture of 80 wt.-% of n-pentane and 20 wt.-% of isopentane. To this blowing agent containing melamine/formaldehyde precondensate 0.1 wt.-% AgNO.sub.3, based on the precondensate, was added in case of Example 6. This mixture was stirred vigorously and then foamed in a mould of polypropylene by irradiation of microwave energy at 2.54 GHz. The foam was afterwards cured in an oven at 100° C. and annealed at 240° C.

[0055] The effect of adding 0.1 wt % AgNO.sub.3 as antimicrobial agent was tested by the above described test procedure for cleaning test for M:F ratios of greater (Comparative Examples C3 and C4) and smaller 0.5 (Examples 5 and 6) and summarized in Table 2. In both cases the pristine resins (Examples C3 and 5) perform better than the silver-modified systems (Examples C4 and 6). The mechanical/elastic properties (ram pressure) of systems with M:F <0.5 (Examples 5 and 6) are better and less strokes are needed for cleaning than for systems with M:F >0.5 (Examples C3 and C4).

[0056] This finding is also reflected in the mechanical properties according to ram pressure, where typical ram pressures for M:F <0.5 are 30N and 23N without and with 0.1 wt % AgNO.sub.3, respectively and for M:F >0.5 are 13N and 7N without and with 0.1 wt % AgNO.sub.3, respectively.

TABLE-US-00002 TABLE 2 melamine- Mean Ram formaldehyde number of pressure Example precondensate AgNO.sub.3 strokes [N] C3 mf-3 (M/F >0.5) — 11 13 C4 mf-3 (M/F >0.5) 0.1 wt.-% 12 7 6 mf-1 (M/F <0.5) — 5 30 7 mf-1 (M/F <0.5) 0.1 wt.-% 8 23