EP2508805B1 - Lubricant - Google Patents

Description

The present invention relates to a lubricant according to the preamble of claim 1.

In the area of the pull-out guide with the application in the higher temperature range, many of the known lubricants reach the limits of material load capacity. Many of the known liquid lubricants, such as, for example, polyfluorinated compounds, can no longer be used despite their excellent lubricating and lubricating properties in the higher temperature range.

Therefore, it is a technical challenge to create a corresponding fitting, in particular a pullout guide, which always has consistently good lubricating and sliding properties below room temperature as well as at temperatures up to 600 ° C. Furthermore, a chemical resistance of the coating and a cost-effective production and application of the same is required.

The EP 1 589 291 A1 discloses a generic drawer slide, which has rolling elements which are mounted in a rolling cage. In this case, the Wälzkörperkäfig on a smear layer, which, inter alia, the inclusion of boron nitride in a paint provides. The coating extends over the entire surface of the Wälzkörperkäfigs. Since boron nitride is used only for reasons of cost in areas in which its special material properties are absolutely necessary, when using this compound, the most cost-effective application is required. A large area coating like in EP 1 589 291 A1 is therefore not useful. A similar pullout guide is in the DE10 2004 019 102A1 disclosed.

Object of the present invention is to provide a lubricant that allows for the use of low and when using high temperatures over a long period of smooth guidance.

This object is achieved by a lubricant having the features of claim 1.

The application of the lubricant is preferably carried out as a sliding paste or as a suspension. This allows the lubricant to be used for industrial series production. In addition, these application forms enable a very exact selection and coating of the application surfaces.

Both the use of the relatively inexpensive graphite as a further lubricant component and high-temperature fat as matrix and carrier additionally support the lubricating and lubricating action of boron nitride. However, while graphite emits embedded water molecules at longer heating times, which reduces its lubricating effect for a short time, it remains with boron nitride even at high temperatures, in particular over 200 ° C.

The lubricant has a temperature resistance of over 600 ° C, which allows for example in the range of cooking ovens and their purification by pyrolysis.

It is also advantageous if the lubricant has a thixotropy, which decreases in these pastes under mechanical action whose viscosity and the original viscosity sets only after prolonged standing again. As a result, the pastes can be relatively easily distributed on the surface of the drawer guides under pressure load. This is the case with BNC pastes, for example.

The viscosity of a lubricant without the addition of solids is advantageously in the range between 50-1500 mm ² / s, preferably 100-1000 mm ² / s, whereby an application of the low to medium viscosity mass can be carried out without the lubricant at the ends the lanes can flow out.

It is also advantageous if the lubricant is so hydrophobic that a bacterial or fungal attack of the lubricant is excluded.

The low surface tension in conjunction with a pronounced surface activity at 25 ° C. of 20-22 mN / m, preferably 20.9-21.2 mN / m, allows full wetting of a large surface under application despite the high viscosity of a lubricant.

Depending on the carrier substance, it is decomposed predominantly into water and carbon dioxide during the pyrolysis. By operating the pullout guide during use by the user, the boron nitride and graphite content in the lubricant mixture was uniformly distributed in the tracks of the pullout guide with the aid of the carrier material. After decomposition of the carrier substance during the pyrolysis, at least the boron nitride remains in the tracks of the pullout guide and enables a smooth operation of the pullout guide, thus it is still lubricated. Due to the mechanical load prior to pyrolysis, the boron nitride / graphite content in the mixture is incorporated into the raceways of the pullout guide. The lubricant of the invention is particularly suitable for the lubrication of fittings in household appliances such as ovens or refrigerators, through its range of use of about - 50 ° C to about 600 ° C. For other areas, the application of the lubricant is conceivable, especially in areas where a food suitability is required. In addition to pullout guides, hinges, flap fittings or other moving parts, in particular on household appliances, can also be lubricated with the lubricant according to the invention.

In order to meet all requirements for the carrier substance for their suitability for foodstuffs, it is preferred to use lubricants that comply with the FDA 21 CFR 178.3570 (US Food and Drug Administration) guideline.

In addition, the lubricants should be registered by the NSF (National Sanitation Foundation) in category H1. Reference is also made to ISO 21469.

In the United States, US DA (H1) approval may also be required. It should be noted that the relevant regulation is to become Directive 21 CFR 178.3570.

The lubricants used preferably also meet the hygiene requirements according to the German version DIN EN ISO 21469: 2006.

• Figur 1 : eine perspektivische Ansicht einer Auszugsführung in der eingefahrenen Position;
• Figur 2 : eine perspektivische Ansicht der Auszugsführung der Figur 1 in der ausgefahrenen Position;
• Figur 3 : eine Explosionsdarstellung der Auszugsführung der Figur1;
• Figur 4 : eine Schnittansicht der Auszugsführung der Figur 1, und
• Figur 5 : eine Schnittansicht der Auszugsführung der Figur 1.
• Figur 6 : ein Diagramm zur Darstellung des erfindungsbedingten Effekt auf die Auszugsführungen

The invention will be explained in more detail using an exemplary embodiment with reference to the accompanying drawings. Show it:

• FIG. 1 a perspective view of a pullout guide in the retracted position;
• FIG. 2 : a perspective view of the pullout guide of FIG. 1 in the extended position;
• FIG. 3 : an exploded view of the pullout guide of the Figur1 ;
• FIG. 4 a sectional view of the pullout guide of FIG. 1 , and
• FIG. 5 a sectional view of the pullout guide of FIG. 1 ,
• FIG. 6 : a diagram illustrating the invention-related effect on the pullout guides

A pullout guide 1 comprises a guide rail 2 and a running rail 3 movable relative to the guide rail. The guide rail 2 and the running rail 3 are made of a bent sheet steel.

The guide rail 2 can be fixed to a side wall of a baking oven and on the running rail 3, a food support can be placed accordingly. The track 3 is movably mounted on the guide rail 2 via rolling elements 4. For this purpose, the guide rail 2 in the longitudinal direction of a plurality of raceways 6 for the spherical rolling elements 4, which are held in a rolling element cage 5.

In order to ensure smooth running of the running rail 3, a lubricant 7 is applied to a portion of the raceways 6 each. By rolling the rolling elements 4 on the sections with the lubricant 7, this is distributed over the entire track 6 on the guide rail 2 and on the raceways 8, which are formed on the running rail 3.

In the illustrated embodiment, a pullout guide with a running rail 3 and a guide rail 2 is described. It is of course also possible to form the pullout guide as a full extension and to provide a center rail between the guide rail 2 and the running rail 3.

• Auftragen des Bornitrids als Gleitpaste oder Suspension
• Mischungen aus Graphit, Bornitrid und einem Polysiloxan

The application of a lubricant with boron nitride and graphite can be carried out in the following ways:

• Apply the boron nitride as a sliding paste or suspension
• Blends of graphite, boron nitride and a polysiloxane

Lubricants and lubricants are boron nitride and graphite, which, due to their hexagonal structure, are relatively easy to disperse when rubbed on a surface and subsequently prevent friction.

The mixture of powder of boron nitride BN and graphite C in the mass ratio of 10% BN / 90% C to 80% BN / 20% C leads to a powder with different gray levels. The mixture BNC has tribological and other physical and chemical properties, which makes it possible to use it as a dry lubricant with hygroscopic properties in the household appliance sector.

The powder has sufficient sliding properties after high temperature stress as it can occur in pyrolysis (self-cleaning process in the oven at 600 ° C), as well as at minus temperatures in freezers. The temperature stress has a different influence on the mixed substances at common temperatures in the oven, the sliding friction of both substances is taken. With the vesicle-containing range up to 100 ° C, as well as with high air humidity, the main lubricating effect of graphite, which unfolds its lubricating effect in the presence of moisture best. In the low temperature range and temperatures above 400 ° C, the lubricating effect is mainly at BN.

The BNC mixture can also be further processed with different methods. Suitable methods of application are spraying with a wet carrier, brushing and wet carrier, mixing by means of drum technique or dipping in a wet carrier. Furthermore, a spraying process via nozzles, even with pasty consistency of the mixture, conceivable.

If the BNC powder is mixed with a wet carrier such as water, alcohol or food oils, fats together, then depending on the Nassträger a suspension (heterogeneous solid / liquid mixture), a dispersion (homogeneous solid / liquid mixture) or an emulsion (heterogeneous liquid / liquid mixture). The subsequent mixture may consist of solid / liquid substances, which are then further processed in the above-mentioned processes.

Both boron nitride and carbon have hexagonal and cubic modifications of their crystal structure, with hexagonal carbon modification widely known as graphite and cubic modification as diamond. Similar to graphite, the hexagonal boron nitride also has a layer structure, with the overlapping layers being relatively easy to shift relative to one another and thus producing a sliding and lubricating effect. These synergies between graphite and boron nitride allow for mixing in the ratios mentioned.

The performance of the BNC-Si lubricants used is based on a physical and tribochemical effect for use in extracts and hinges. This occurs particularly advantageous in the range of -50 to + 220 ° C. With a consistently high mechanical load, you will get an almost constant viscosity within the specified temperature range. The viscosity of BNC-Si lubricant is in the range between 100-1000 mm ² / s, is determined at 25 ° C according to DIN 51562 and classifies the BNC-Si lubricants in the category of low to medium viscosity substances. Due to the high hydrophobicity of the lubricants form a corrosion protection, which leads neither to bleeding in the temperature range, nor to oil secretions, even over long periods of time. The viscosity data refer to the lubricants without added solids.

• der Viskositätstemperaturkoeffizient liegt zwischen 0,5-0,7, vorzugsweise zwischen 0,60-0,62;
• die Verdampfungswärme liegt bis 200°C zwischen 150-300 J/g, vorzugsweise zwischen 220-240 J/g;
• der Siedepunkt bei 0,5 mbar liegt zwischen 100-300°C, vorzugsweise zwischen 150-230°C;
• der Stockpunkt gemäß DIN 51583 liegt zwischen -50-10°C, vorzugsweise zischen - 30--10°C;
• der Flammpunkt liegt nach DIN 51376 zwischen 230-370°C, vorzugsweise 275-321 °C
• der Zündpunkt liegt nach DIN 51794 über 400°C, vorzugsweise über 420°C
• der Tropfpunkt liegt nach ASTM-D-445 zwischen -80°C - -30°C, vorzugsweise zwischen -65°C und -50°C.

In connection with the temperature resistance of the BNC-Si, the following properties can be mentioned:

• the viscosity temperature coefficient is between 0.5-0.7, preferably between 0.60-0.62;
• the heat of vaporization is up to 200 ° C between 150-300 J / g, preferably between 220-240 J / g;
• the boiling point at 0.5 mbar is between 100-300 ° C, preferably between 150-230 ° C;
• the pour point according to DIN 51583 is between -50-10 ° C, preferably hissing - 30--10 ° C;
• the flash point is according to DIN 51376 between 230-370 ° C, preferably 275-321 ° C.
• the ignition point is in accordance with DIN 51794 over 400 ° C, preferably above 420 ° C.
• the dropping point according to ASTM-D-445 is between -80 ° C - -30 ° C, preferably between -65 ° C and -50 ° C.

Additional disturbing noises, such as squeaking, do not occur when using BNC-Si lubricants. Here, a high pressure absorption capability comes into play. Thus, a provided with BNC silicone lubricant drawer slide even under high mass load, for example by Gargutträger, consistently good sliding properties.

After the pyrolysis treatment of the BNC paste, a lubricating film remains, which provides the functionality of the extracts.

The BNC-Si lubricant is applied with silicone oil. The low surface tension in conjunction with a pronounced surface activity at 25 ° C. of 20-22 mN / m, preferably 20.9-21.2 mN / m, allows complete wetting of a large surface area during application. In order to make the viscosities of BNC-Si lubricants variable, other solvents can be added to the lubricant.

A BNC-Si lubricant layer is highly water-repellent and chemically inert to vegetable oils, mineral oils, gases, dilute acids and alkalis as well as most aqueous solutions. Due to its highly hydrophobic properties also a bacterial or fungal attack of the lubricant is excluded. In addition, BNC-Si lubricants are radiation resistant, oxidation resistant, non-toxic, non-flammable and physiologically inert and odorless.

The color of the lubricant is adjustable by the BNC ratio.

All ingredients of the BNC-Si lubricant comply with the USDA and FDA regulations and are therefore suitable for use in the food industry.

In addition, according to the Food and Consumer Goods Act (§5, para. 1 no. 1 of 15.08.1974 BGBL.IS 1945) there are no concerns for the use of silicone carriers and phenylmethyl silicone oils, having a viscosity of ≥ 100 mm ² / s at 20 ° C, in the food industry.

In FIG. 6 Measurements are shown in the form of a diagram, which can be described the properties of a BNC-Si paste, which was applied as a lubricant on an electrodeposited aluminum surface.

1. a) Kraftaufwand beim Ausziehen der Auszugsführung (Fa) in N
2. b) Kraftaufwand beim Einfahren der Auszugsführung (Fe) in N
3. c) Laufgüte, beurteilt durch eine geschulte Prüfperson mittels Ordinalskala
4. d) Geräusche, beurteilt durch eine geschulte Prüfperson mittels Ordinalskala

In the test test, the results of which are shown in the diagram, a pull-out guide equipped with the BNC-Si paste was tested for frequent use of the pull-out guide for the following properties:

1. a) force when pulling out the pullout guide (Fa) in N
2. b) force when retracting the pullout guide (Fe) in N
3. c) running quality, assessed by a trained examiner using ordinal scale
4. d) noises, assessed by a trained examiner using ordinal scale

In the experiment, the pullout guide with 15000 double strokes, ie a extension and retraction of the pullout guide, was tested for wear. At the beginning of the measurement, the pull-out rail was subjected several times to pyrolysis cycles of 500 ° C., which were repeated once in each case after 750 double strokes. This serves to simulate the conditions to which the drawer runner is exposed in pyrolysis furnaces.

The pullout guide was loaded during this experiment with a mass of 11 kg and subjected to a total of 100 pyrolysis runs.

The forces which were used to pull out the pullout guide were in the range between 3.5 and 6.5 N, the fluctuations being relatively constant around a mean value of 5.0 N and observed no increase or decrease in the force on average is.

Similar observations can be made with the forces that must be applied to retract the drawer rail. Here, in a range from 1.5 to 4.0 N, comparably high fluctuations occur around a mean value of 2.3 N.

The measurement results show a consistent runnability with quiet running with little effort (classification 1-7, where 1 of the highest running quality, with smooth running, and 7 of the lowest running quality, with blocking and halting run, corresponds).

The measurement results also show a constant mobility with quietly pounding barrel (classification 1-7, where 1 is defined as discreet noise and 7 as disturbing, booming noise).

From material trials, the following picture emerged: test number lubrication composition double strokes pyrolysis test result test result 1 BN: C: NO paste 25:25:50 BNC: oil 17500 60 Gray coloration of the surface Running test went trouble-free 2 BN: C: Si paste series state degreased 25:25:50 15000 40 Gray coloration of the surface Running test was trouble-free 3 BN: C: NO paste degreased series 48: 48: 4 15000 44 Gray coloration of the surface Running test was trouble-free 4 C: Si: H ₂ O paste series state degreased 36: 2: 62 15000 18 Gray coloration of the surface Running test was trouble-free 5 BN: C: PFPE 25:25:50 15000 40 Gray coloration of the surface Running test was trouble-free 6 BN: C: Si paste series state degreased 25:25:50 15000 100 Gray coloration of the surface Running test was trouble-free

The compositions which are listed in the table refer in each case to percentage mass fractions. With Si, the percentage mass fractions of silicone oils or silicone pastes were characterized. NO was used to denote the percentage by weight of native oils. PFPE was used to denote the percentage by weight of perfluoroethyloxide oil.

The composition under test number 2 or 6 according to the invention. Thus, even after 100 cleaning cycles, according to test number 6, this formulation shows no change in the running properties or runnability.

The silicone oil used in this exemplary composition consists essentially of polydimethylsiloxane, moreover, the particle size of the hexagonal boron nitride used is about 5 microns and the particle size of the graphite used also about 5 microns. A particle size of about 5 microns shows a particularly good lubricating property. Investigated were investigated particle sizes in the range of 0.1 microns to 8 microns.

Due to the particle size and the roughness of the friction partners, the boron nitride and graphite particles roll into the surfaces. The rolled-in BNC particles can not be removed from the pull-out guides in the dishwasher after only 100 double strokes. After 25 cleaning applications in the intensive cleaning program, the drawer slides are still fully functional. Thus, a dishwasher resistance is achieved. Household and industrial dishwashers were used to investigate dishwasher safety.

Both the particle sizes of the boron nitride and of the graphite are subject to a certain fluctuation range. In addition, depending on the composition of the mixtures, the particle sizes can vary between 0.1-500 μm.

Use of synthetic graphite has proven to be advantageous as it is more uniform in structure and grain size distribution. Preferably, the fraction was used with a particle size of about 5 microns.

• 1.Mischung (nicht erfindungsgemäß):
  • Graphit 20-50%, vorzugsweise 30-40%
  • Silikonöl 0.5-5%, vorzugsweise 1-3%
  • Wasser 45-79.5%, vorzugsweise 57-69%
• 2.Mischung (nur bereichsweise erfindungsgemäß):
  • Bornitrid 10-40%, vorzugsweise 20-30%
  • Graphit 10-40%, vorzugsweise 20-30%
  • Silikonöl 20-80%, vorzugsweise 40-60%
  • (erreichte Viskosität beträgt hierbei 1000 mm²/s)
• 3.Mischung (nicht erfindungsgemäß):
  • Bornitrid 10-40%, vorzugsweise 20-30%
  • Graphit 10-40%, vorzugsweise 20-30%
  • Perfluorethyloxidöl 20-80%, vorzugsweise 40-60%
• 4.Mischung (nicht erfindungsgemäß):
  • Bornitrid 10-40%, vorzugsweise 20-30%
  • Graphit 10-40%, vorzugsweise 20-30%
  • Olivenöl 20-80%, vorzugsweise 40-60%
  • (erreichte Viskosität beträgt hierbei 100 mm²/s)
• 5.Mischung (nicht erfindungsgemäß):
  • Bornitrid 30-70%, vorzugsweise 40-60%
  • Graphit 30-70%, vorzugsweise 40-60%
  • Olivenöl 1-10%, vorzugsweise 1-5%
• 6. Mischung (nicht erfindungsgemäß):
  • Bornitrid 15-35%, vorzugsweise 20-30%
  • Graphit 15-35%, vorzugsweise 20-30%
  • Perfluorethyloxidöl 30-70%, vorzugsweise 40-60%
• 7. Mischung (nicht erfindungsgemäß):
  • Graphit 30-70%, vorzugsweise 40-60%
  • Silikonöl 30-70%, vorzugsweise 40-60%8. Mischung (nicht erfindungsgemäß):
    • Bornitrid 30-70%, vorzugsweise 40-60%
    • Perfluorethyloxidöl 30-70%, vorzugsweise 40-60%
• 9. Mischung (nicht erfindungsgemäß):
  • Bornitrid 30-70%, vorzugsweise 40-60%
  • Silikonöl 30-70%, vorzugsweise 40-60%

In the following, several possibilities for compositions of lubricants in the high temperature range (in mass fractions w) are listed:

• 1st mixture (not according to the invention):
  • Graphite 20-50%, preferably 30-40%
  • Silicone oil 0.5-5%, preferably 1-3%
  • Water 45-79.5%, preferably 57-69%
• 2.Mixture (only regionally according to the invention):
  • Boron nitride 10-40%, preferably 20-30%
  • Graphite 10-40%, preferably 20-30%
  • Silicone oil 20-80%, preferably 40-60%
  • (reached viscosity is 1000 mm ² / s)
• 3.Mixture (not according to the invention):
  • Boron nitride 10-40%, preferably 20-30%
  • Graphite 10-40%, preferably 20-30%
  • Perfluoroethyloxide oil 20-80%, preferably 40-60%
• 4.Mixture (not according to the invention):
  • Boron nitride 10-40%, preferably 20-30%
  • Graphite 10-40%, preferably 20-30%
  • Olive oil 20-80%, preferably 40-60%
  • (reached viscosity is 100 mm ² / s)
• 5.Mixture (not according to the invention):
  • Boron nitride 30-70%, preferably 40-60%
  • Graphite 30-70%, preferably 40-60%
  • Olive oil 1-10%, preferably 1-5%
• 6. Mixture (not according to the invention):
  • Boron nitride 15-35%, preferably 20-30%
  • Graphite 15-35%, preferably 20-30%
  • Perfluoroethyloxide oil 30-70%, preferably 40-60%
• 7. Mixture (not according to the invention):
  • Graphite 30-70%, preferably 40-60%
  • Silicone oil 30-70%, preferably 40-60% 8. Mixture (not according to the invention):
    • Boron nitride 30-70%, preferably 40-60%
    • Perfluoroethyloxide oil 30-70%, preferably 40-60%
• 9. Mixture (not according to the invention):
  • Boron nitride 30-70%, preferably 40-60%
  • Silicone oil 30-70%, preferably 40-60%

The viscosity of the liquid lubricant can be varied without departing from the scope of the inventive concept.

Other greases meeting US FDA purity requirements. Food and Drug Administration according to Directive 21 CFR 178.3570 can also be used. The same applies to greases that have been registered by the NSF (National Sanitary Foundation) in category H1 - in this case, reference is additionally made to ISO 21469.

Thus, the lubricant meets the testing standards of DIN 21469: 2006 as a food grade lubricant.

Claims (3)

1. A lubricant for fittings in domestic appliances, wherein the lubricant (7) contains boron nitride and silicone oil as a polysiloxane and has a temperature resistance of -50°C up to over 600°C and is substantially a mixture of boron nitride, graphite and silicone oil, characterized in that the lubricant contains boron nitride in a mass fraction w (boron nitride) of between 20% up to 30%, graphite in a mass fraction w (graphite) of between 20% up to 30% and silicone oil in a mass fraction w (silicone oil) of between 45% up to 55%.
2. A lubricant according to claim 1, characterized in that boron nitride is contained in a mass fraction w (boron nitride) of 25%, that graphite is contained in a mass fraction w (graphite) of 25% and that silicone oil is contained in a mass fraction w (silicone oil) of 50%.
3. Use of the lubricant according to claim 1 for lubricating fittings of ovens or cooling devices.

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