How to clean medical equipment

Abstract

1. A method for cleaning a medical instrument by scrubbing the instrument with an open-cell melamine-formaldehyde foam containing an antimicrobially active composition, wherein the open-cell melamine-formaldehyde foam is prepared from a melamine-formaldehyde precondensate, the melamine-formaldehyde precondensate having a molar ratio of melamine to formaldehyde of less than 0.5.

Description

[Technical field]

[0001] The present invention relates to a method for cleaning medical instruments by scrubbing the instrument with a melamine-formaldehyde foam that contains an antimicrobially active composition. [Background technology]

[0002] EP 1 505 105 A1 discloses a moulded article of melamine / formaldehyde foam having less than 0.1 ppm of formaldehyde determined according to DIN 55666, which is obtainable by the following steps: a) preparing a foam from a melamine / formaldehyde precondensate having a melamine:formaldehyde molar ratio of more than 0.5, b) annealing the foam obtained at less than 200°C, c) moulding the annealed foam in a press at 160-240°C and an absolute pressure of 5-100 bar in the course of 15-120 seconds to obtain a moulded article.

[0003] WO 01 / 94436 relates to a method for producing a resilient foam material based on a melamine / formaldehyde condensation product. According to the method of the invention, a precondensate having a molar ratio of melamine to formaldehyde of more than 1:2 is foamed. Substantially no formaldehyde is released from the foamed material.

[0004] WO 2012 / 035457 and US 2012 / 071578 relate to a process for producing melamine-formaldehyde foams comprising the following successive steps a) and b): a) heating a mixture comprising a melamine-formaldehyde precondensate, a hardener and a blowing agent to foam and crosslink the mixture, and b) tempering the foam obtained in step a). WO 2012 / 035457 and US 2012 / 071578 relate to a process for producing melamine-formaldehyde foams comprising the following successive steps a) ...

[0005] Patent document 5 (US 2018 / 140157 A1) discloses a cleaning implement made from a melamine-formaldehyde foam containing 0.1 to 5% by weight of at least one linear polymer, preferably polyethylene glycol, having a number average molecular weight Mn in the range of 500 to 10,000 g / mol.

[0006] Patent document 6 (WO 2008 / 110475) relates to a method for producing a foam containing at least one antibacterial active agent, which method comprises the following steps: (1) producing a solution or dispersion containing at least one precondensate of the foam to be produced and at least one antibacterial active agent, (2) heating the solution or dispersion from step (1) to foam the precondensate to obtain a foam with at least one antibacterial active agent, (3) tempering the foam obtained in step (2) at a temperature of 120 to 300 ° C. The foams thus produced can be used for thermal and sound insulation of buildings and building parts, for thermal and sound insulation of interior spaces of vehicles and aircraft, for low temperature insulation, as insulating wall coverings, as thermal insulation and impact damping packaging materials, as abrasive action cleaning, grinding and polishing sponges, in the hygiene field and as filter materials.

[0007] WO 2014 / 037233 discloses a method for producing melamine-formaldehyde foam, the process comprising heating and foaming a mixture comprising at least one melamine-formaldehyde pre-condensate, at least one hardener, a surfactant mixture, at least one salt of an inorganic acid and / or an organic carboxylic acid, and at least one blowing agent using microwave radiation.

[0008] Patent document 8 (WO 2009 / 136957) discloses a contoured (contoured) sterilisation element for wiping and sterilising surfaces of medical devices containing anti-pathogenic substances and absorbents, resilient articles such as viscoelastic polyurethane foams.

[0009] Patent document 9 (US 2010 / 200017) discloses a microbiological scrub brush with a semi-closed hydrophilic polyurethane medical grade foam insert impregnated with an antibacterial disinfectant.

[0010] WO 2016 / 044821 discloses a method and device for cleaning a central venous catheter port. The device includes a body, a coupling configured to connect the body to a hub, a cleaning cap coupled to the body, and an actuator disposed within the body for rotating and translating the cap relative to the hub. The cleaning cap includes a cap body defining a cavity and a cleaning member disposed within the cavity, the cleaning member having threads that engage threads on the hub.

[0011] Patent document 11 (US 2017 / 0333156) discloses a system for disinfecting central venous catheter (CVC) system ports using an open-cell micro-abrasive formaldehyde-melamine-sodium bisulfite foam containing a disinfectant solution. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] EP 1 505 105 A1 [Patent Document 2] WO 01 / 94436 [Patent Document 3] International Publication No. 2012 / 035457 [Patent Document 4] US 2012 / 071578 [Patent Document 5] US 2018 / 140157 A1 [Patent Document 6] International Publication No. 2008 / 110475 [Patent Document 7] International Publication No. 2014 / 037233 [Patent Document 8] International Publication No. 2009 / 136957 [Patent Document 9] US 2010 / 200017 [Patent Document 10] International Publication No. 2016 / 044821 [Patent Document 11] US 2017 / 0333156 Summary of the Invention [Problem to be solved by the invention]

[0013] The present invention has been made in view of the above-mentioned prior art, and an object of the present invention is to provide a method for killing bacteria and at the same time removing or reducing the amount of biofilm adhesion on a medical device. [Means for solving the problem]

[0014] To achieve the above object, the present invention provides a method for cleaning a medical instrument by scrubbing the instrument with a melamine-formaldehyde foam comprising an antimicrobially active composition, wherein the melamine-formaldehyde foam is prepared from a melamine-formaldehyde precondensate, the melamine-formaldehyde precondensate having a molar ratio of melamine to formaldehyde of less than 0.5.

[0015] Preferred embodiments of the method according to the invention are set out in claims 2-7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The melamine-formaldehyde foams can be produced by heating and foaming an aqueous mixture M comprising at least one melamine-formaldehyde precondensate, at least one hardener, at least one surfactant and at least one blowing agent using microwave radiation. A suitable process is described in WO 2014 / 037233.

[0017] Commercially available melamine-formaldehyde precondensates are useful in many fields of use, for example for further processing into adhesives. Melamine-formaldehyde precondensates containing sulfite groups are advantageous for use in some of these fields. Such sulfite-containing melamine-formaldehyde precondensates are obtained, for example, as described in EP-B 37470, in which 1% to 20% by weight of sodium disulfite are incorporated in the course of the condensation of melamine and formaldehyde to give co-condensed sulfite groups.

[0018] However, in the process of the present invention the melamine-formaldehyde precondensate preferably contains less than 1% by weight, preferably less than 0.1% by weight of sulfite groups, and most preferably the melamine-formaldehyde precondensate is essentially free of sulfite groups.

[0019] The mechanical / elastic properties or melamine-formaldehyde foams depend on the molar ratio of melamine to formaldehyde (M:F) in the melamine-formaldehyde precondensate. The molar ratio of melamine to formaldehyde in the melamine-formaldehyde precondensate is preferably less than 0.5, and more preferably in the range of 1:2.1 to 1:3.9, and most preferably in the range of 1:2.5 to 1:3.5. The molar ratio of melamine to formaldehyde used to prepare the melamine-formaldehyde precondensate can be determined by nuclear magnetic resonance (NMR) spectroscopy and integration of the peak areas of the methylene and methylol bridging units.

[0020] In addition to melamine and formaldehyde, the melamine-formaldehyde precondensate may contain 50% by weight and preferably up to 20% by weight of other thermosetting formers in co-condensed form (based on the weight of all co-condensed melamine-formaldehyde precondensate). Useful thermosetting formers include, for example, alkyl and aryl-alkyl substituted melamines, ureas, urethanes, carboxamides, dicyandiamides, guanidines, sulfurylamides, sulfonamides, aliphatic amines, glycols, phenols and their derivatives. Examples of useful other aldehydes are acetaldehyde, trimethylolacetaldehyde, acrolein, benzaldehyde, furfurol, glyoxal, glutaraldehyde, phthalaldehyde and terephthalaldehyde. Particularly preferred are unmodified melamine-formaldehyde precondensates, ie, melamine-formaldehyde precondensates lacking other thermoset formers or other aldehydes.

[0021] Anionic, cationic and nonionic surfactants and mixtures thereof can be used as emulsifiers for emulsifying the foaming agent and stabilizing the foam.

[0022] Useful anionic surfactants include, for example, diphenylene oxide sulfonates, alkane and alkylbenzene sulfonates, alkylnaphthalene sulfonates, olefin sulfonates, alkyl ether sulfonates, fatty alcohol sulfates, ether sulfates, α-sulfo fatty acid esters, acylaminoalkane sulfonates, acyl isethionates, alkyl ether carboxylates, N-acylsarcosinates, alkyl and alkyl ether phosphates. Useful nonionic surfactants include, for example, alkylphenol polyglycol ethers, fatty alcohol polyglycol ethers, fatty acid polyglycol ethers, fatty acid alkanolamides, ethylene oxide-propylene oxide block copolymers, amine oxides, glycerol fatty acid esters, sorbitan esters and alkyl polyglycosides. Useful cationic emulsifiers include, for example, alkyltriammonium salts, alkylbenzyldimethylammonium salts and alkylpyridinium salts.

[0023] The emulsifier is preferably added in an amount of 0.2% to 5% by weight, based on the meramine-formaldehyde precondensate.

[0024] Preferably, a surfactant mixture is used as an emulsifier comprising a mixture of 50-90% by weight of at least one anionic surfactant and 10-50% by weight of at least one nonionic surfactant, where the weight percentages are each based on the total weight of the surfactant mixture. Most preferably, a surfactant mixture of 10-50% by weight of at least one alkane sulfonate and 50-90% by weight of at least one alkyl polyethylene glycol ether is used.

[0025] As hardeners, acidic compounds that catalyze the further condensation of the melamine formaldehyde resin can be used. The amount of these hardeners is generally in the range of 0.01% to 20% by weight, and preferably in the range of 0.05% to 5% by weight, all based on the precondensate. Useful acidic compounds include those selected from the group consisting of organic and inorganic acids, such as hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, formic acid, acetic acid, oxalic acid, toluenesulfonic acid, amidosulfonic acid, acid anhydrides, and mixtures thereof.

[0026] Preferably, formic acid is used as the hardening agent.

[0027] The mixture includes a blowing agent. The amount of blowing agent in the mixture generally depends on the desired density for the foam. Preferably, in relation to the melamine-formaldehyde precondensate, this amount is such that the foam has a density of 8 to 12 kg / m 3 , more preferably 9 to 11 kg / m 3 is selected so that

[0028] In principle, the process of the present invention can use both physical and chemical blowing agents. Useful blowing agents include, for example, hydrocarbons such as pentane, hexane, halogenated, more particularly chlorinated and / or fluorinated, hydrocarbons such as methylene chloride, chloroform, trichloroethane, chlorofluorocarbons, hydrochlorofluorocarbons (HCFCs), alcohols such as methanol, ethanol, n-propanol or isopropanol, ethers, ketones and esters such as methyl formate, ethyl formate, methyl acetate or ethyl acetate in the liquid state or as a gas, air, nitrogen or carbon dioxide.

[0029] The mixture further comprises at least one blowing agent, which is present in the mixture in an amount of 0.5% to 60% by weight, preferably 1% to 40% by weight, more preferably 1.5% to 30% by weight, based on the melamine-formaldehyde precondensate. It is preferable to add a physical blowing agent having a boiling point in the range of 0 to 80° C. Pentane is preferably used as the blowing agent.

[0030] The precondensate is generally foamed by heating a suspension of the melamine-formaldehyde precondensate to obtain a foamed material.

[0031] The introduction of energy may preferably be via electromagnetic radiation, for example via high frequency radiation in the frequency range of 0.2-100 GHz, preferably 0.5-10 GHz, at 5-400 kW, preferably 5-200 kW, and more preferably 9-120 kW per kilogram of mixture. Magnetrons are a useful source of inductive radiation, and it is possible to use one magnetron or two or more magnetrons simultaneously.

[0032] The mixture to be foamed is irradiated immediately after it emerges from the foaming die. The blowing agent evaporates and the resin mixture foams and hardens at the same time. The produced foam material is finally dried to remove residual water and blowing agent from the foam. To improve elasticity, the foam may be tempered and / or pressed.

[0033] The melamine-formaldehyde foam preferably has an open-cell structure. Preferably, the melamine-formaldehyde foam has an open-cell content of more than 50%, more particularly more than 95%, measured according to DIN ISO 4590. The density of the foam is between 8 and 12 kg / m 3 is preferably 9 to 11 kg / m 3 It is more preferable that:

[0034] The melamine-formaldehyde foam comprises an antimicrobial active composition, which comprises one or more antimicrobial actives. Suitable antimicrobial actives include alcohols, such as ethanol, hexanol, n-propanol or isopropanol, quaternary ammonium compounds, such as benzalkonium chloride, or halogenated compounds, such as triclosan, 2,4-dichlorobenzyl alcohol, chlorhexidine gluconate or povidone iodine.

[0035] Preferably, a solution or dispersion containing isopropyl alcohol, chlorhexidine gluconate or povidone iodine or a mixture thereof is used as the antimicrobial active composition.

[0036] Preferably the open-cell melamine formaldehyde foam comprises 0.1 to 10% by weight of the antimicrobially active composition.

[0037] The antimicrobially active composition or substance may be incorporated into the melamine-formaldehyde foam and / or the melamine-formaldehyde foam may be coated or filled with the antimicrobially active composition prior to the step of foaming the precondensate by heating a solution or dispersion of the melamine-formaldehyde precondensate in the presence of a blowing agent as described in WO 2008 / 110475. Preferably, the melamine-formaldehyde foam is immersed in a solution or dispersion of the antimicrobially active composition and subsequently squeezed.

[0038] Preferably, the melamine-formaldehyde foam has an open-cell structure that is wholly or partially filled with a solution or dispersion containing isopropyl alcohol, chlorhexidine gluconate or povidone iodine or mixtures thereof as the antimicrobial active composition.

[0039] The method according to the invention is particularly useful for removing biofilm deposits from medical devices.

[0040] Preferably, the method is applied to clean the medical device, a catheter or endoscope, most preferably a central venous catheter (CVC) system port. EXAMPLES

[0041] The present invention will be described in more detail and specifically below with reference to examples, but the present invention is not limited to these examples.

[0042] Test procedure for cleaning test Test soils based on hand cream and carbon black were prepared and applied to tiles with a doctor blade to obtain a film height of 300 μm. The materials were then baked onto the tiles in an oven at 160° C. for 10 minutes. The tiles prepared as described above were cleaned with a melamine formaldehyde sponge and the number of strokes required to remove the soil from the surface was measured.

[0043] Ram pressure value [N]: All stamp pressure value measurements for evaluating the mechanical / elastic properties of melamine / formaldehyde foams were performed as follows: a cylindrical steel die, 8 mm in diameter and 10 cm in height, was applied perpendicularly to a cylindrical foam sample, 11 cm in diameter and 5 cm in height, pressing and breaking the foam sample. The maximum force (in N) applied by the plunger until the foam sample tears, also referred to below as the ram pressure value, provides information about the foam mechanical / elastic quality (measurements reported in Table 1 in each case were performed parallel to the foam rise direction). The higher the value of the punch pressure, the better the mechanical / elastic properties of the melamine / formaldehyde foam.

[0044] Materials used: Melamine-formaldehyde precondensate: mf-1: The melamine-formaldehyde precondensate mf-1 was a spray-dried melamine-formaldehyde precondensate having a melamine:formaldehyde molar ratio of 1:3, no further thermoset formers apart from melamine, no further aldehydes apart from formaldehyde and no sulfite groups and having an average molecular weight (number average) Mn of 350 g / mol.

[0045] 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, a melamine:formaldehyde molar ratio of 1:3, no thermosetting substances other than melamine, no more than aldehydes apart from formaldehyde, and a sulfite content of 2.3% by weight (based on the total weight of the melamine-formaldehyde precondensate).

[0046] mf-3: The melamine-formaldehyde precondensate mf-3 was a spray-dried melamine-formaldehyde precondensate with a melamine:formaldehyde molar ratio of 1:1.6, no thermosetting molding agents apart from the melamine, no further aldehydes apart from the formaldehyde, and no sulfite groups.

[0047] sm-1: A surfactant mixture comprising 80% by weight of an alkanesulfonate mixture and 20% by weight of an alkyl polyethylene glycol ether mixture.

[0048] sm-2: A surfactant mixture with 80% by weight of the sodium salt of fatty alcohol polyglycol ether sulfate and 20% by weight of a mixture of alkyl polyethylene glycol ethers.

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

[0050] Example 2 70 parts by weight of spray-dried melamine / formaldehyde precondensate mf-2 was dissolved in 30 parts by weight of water. To this mixture were added 2.75 parts by weight of sodium formate, 3.1 parts by weight of formic acid, 1.5 parts by weight of surfactant mixture sm-1 and 17.8 parts by weight of blowing agent mixture (80% by weight of n-pentane and 20% by weight of isopentane). The mixture was stirred vigorously and then foamed in a polypropylene mold by irradiating with microwave energy at 2.54 GHz. The foam was then cured in an oven at 100°C and annealed at 240°C.

[0051] Tiles prepared by the test procedure described above for cleaning tests were cleaned with melamine formaldehyde sponges prepared from resins with (Example 2) and without (Example 1) bisulfite. The sponges were soaked in isopropanol before cleaning, squeezed dry, and then the number of strokes required to remove the soil from the surface was measured. The results are shown in Table 1.

[0052] The foam from Example 1 required an average of only 5.7 strokes compared to 8.7 strokes for the foam from Example 2. Fewer strokes means more effective cleaning.

[0053] [Table 1]

[0054] Comparative Examples C3 and C4 70 parts by weight of spray-dried melamine / formaldehyde precondensate mf-3 was dissolved in 30 parts by weight of water. To this mixture were added 2.75 parts by weight of sodium formate, 3.1 parts by weight of formic acid, 1.5 parts by weight of surfactant mixture sm-2 and 17.8 parts by weight of blowing agent mixture (80% by weight of n-pentane and 20% by weight of isopentane). In the case of Example C4, 0.1% by weight of AgNO 3 based on the precondensate was added to the melamine / formaldehyde precondensate containing the blowing agent.3 The mixture was stirred vigorously and then foamed in a polypropylene mold by exposure to microwave energy at 2.54 GHz. The foam was then cured in an oven at 100°C and annealed at 240°C.

[0055] Example C5 70 parts by weight of spray-dried melamine / formaldehyde precondensate mf-3 was dissolved in 30 parts by weight of water. To this mixture, 2.75 parts by weight of sodium formate, 3.1 parts by weight of formic acid, 1.5 parts by weight of surfactant mixture sm-1 and 17.8 parts by weight of blowing agent mixture (80% by weight of n-pentane and 20% by weight of isopentane) were added. The mixture was stirred vigorously and then foamed in a polypropylene mold by irradiating with microwave energy at 2.54 GHz. The resulting foam was not stable and collapsed during curing.

[0056] Examples 6 and 7 70 parts by weight of spray-dried melamine / formaldehyde precondensate mf-1 were dissolved in 30 parts by weight of water. To this mixture were added 2.75 parts by weight of sodium formate, 3.1 parts by weight of formic acid, 1.5 parts by weight of surfactant mixture sm-1 and 17.8 parts by weight of a blowing agent mixture (80% by weight of n-pentane and 20% by weight of isopentane). In the case of Example 6, the melamine / formaldehyde precondensate containing the blowing agent was added with 0.1% by weight of AgNO 3 based on the precondensate. 3 The mixture was stirred vigorously and then foamed in a polypropylene mold by exposure to microwave energy at 2.54 GHz. The foam was then cured in an oven at 100°C and annealed at 240°C.

[0057] 0.1% by weight AgNO as an antibacterial agent 3The effect of adding was tested by the test procedures described above for cleaning tests with M:F ratios greater than (Comparative Examples C3 and C4) and less than (Examples 5 and 6) 0.5, and is summarized in Table 2. In all cases, the pristine resins (Examples C3 and 5) perform better than the silver modified systems (Examples C4 and 6). Systems with M:F < 0.5 (Examples 5 and 6) have better mechanical / elastic properties (ram pressure) and require fewer strokes to clean than systems with M:F > 0.5 (Examples C3 and C4).

[0058] This finding is also reflected in the mechanical properties as a function of ram pressure, where typical ram pressures for M:F < 0.5 are AgNO 3 None and 0.1% by mass AgNO 3 , 30N and 23N, respectively, and for M:F>0.5, AgNO 3 None and 0.1% by mass AgNO 3 , which are 13N and 7N respectively.

[0059] [Table 2]

Claims

1. 1. A method of cleaning a medical instrument by scrubbing the instrument with a melamine-formaldehyde foam containing an antimicrobially active composition, comprising: The melamine-formaldehyde foam is prepared from a melamine-formaldehyde precondensate in the presence of a surfactant mixture comprising 50 to 90 weight percent of at least one alkane sulfonate and 10 to 50 weight percent of at least one alkyl polyethylene glycol ether, each weight percentage being based on the total weight of the surfactant mixture. the molar ratio of melamine to formaldehyde of the melamine-formaldehyde precondensate is less than 0.5; A method characterized in that a catheter or an endoscope is used as the medical device.

2. 2. The method of claim 1, wherein the melamine-formaldehyde foam has an open-cell structure with an open cell content of greater than 95%, as measured by DIN ISO 4590.

3. The melamine-formaldehyde foam has a density of 8 to 12 kg / m ３ 3. The method according to claim 1, characterized in that the density is in the range of

4. 4. The method according to claim 1, wherein the melamine-formaldehyde foam has an open-cell structure which is totally or partly filled with a solution or dispersion comprising isopropyl alcohol, chlorhexidine gluconate or povidone-iodine or mixtures thereof as antimicrobial active composition.

5. 5. The method according to claim 1, wherein the melamine-formaldehyde foam comprises 0.1 to 10% by weight of the antimicrobially active composition.

6. 6. The method according to claim 1, wherein the melamine-formaldehyde precondensate is essentially free of sulfite groups.

7. 7. The process according to claim 1, wherein the molar ratio of melamine to formaldehyde in the melamine-formaldehyde precondensate is in the range of 1:2.5 to 1:3.

5.

8. The method according to any one of claims 1 to 7, characterized in that a central venous catheter (CVC) system port is used as the medical device.

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