LUBRICANT SYSTEM FOR REDUCING FRICTIONAL NOISE

A lubricant system for reducing frictional noise includes: a textile fabric at least partially embedded in a lubricant, the lubricant including a comb polymer having a main polymer chain and a plurality of side chains covalently bonded to the main polymer chain. At least one of the side chains has a molecular weight of at least 60 g/mol and/or at least 5 repeat units.

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Description
CROSS-REFERENCE TO PRIOR APPLICATION

Priority is claimed to German Patent Application No. DE 10 2018 131 931.2, filed on Dec. 12, 2018, the entire disclosure of which is hereby incorporated by reference herein.

FIELD

The invention relates to a lubricant system for reducing frictional noise, in particular in the car interior. The invention further relates to a method for producing the lubricant system and to its uses.

BACKGROUND

Frictional noises that arise when surfaces (e.g. plastic surfaces) rub against one another, such as squeaking noises in the car interior, are highly undesirable, since they drastically reduce the impression of high quality, particularly in the case of high-priced products. Such frictional noises are produced by the surfaces rubbing against each other, in particular by static friction that is sometimes very high, which prevents the surfaces from sliding on each other. This effect is described as stick-slip effect in detail in the technical literature [“Origin of Stick-Slip Motion in Boundary Lubrication,” Science 1990, 250, 792-794, doi:10.1126/science. 250.4982.792]. In order to reduce frictional noise, using noise-inhibiting textile tapes is known. Such tapes are applied between the surfaces rubbing against each other and thereby reduce noise development. However, they are disadvantageous in that they significantly increase the distance between the surfaces. A further disadvantage is that they do not work in all friction situations, since their friction-reducing properties are not independent of speed and force.

Using PFPE-based lubricating greases in order to avoid creaking noises in door seals and door profiles, as described, for example, in EP 2721126 B1, is also known.

U.S. Pat. No. 9,371,498 B2 describes the production of a lubricant system by combining fibers or a fiber network as a carrier substrate and an oil or a lubricating liquid. Fibers that are oleophilic and have an affinity for the oil or the lubricating liquid are used in this case. Nonwovens fixed to surfaces can, among other things, be used as the fiber network. An essential feature of the lubricant system described is that a liquid is introduced into the fiber network and is released in a controlled manner during the lubricating process, for example by changing the pH value, the TAN value or the temperature.

The disadvantage of the system described is that there is no permanent binding of the lubricant to the carrier substrate. As a result, the lubricants leak from the carrier material when an external pressure arises, for example. To be sure, leakage of the lubricant in the described system is also necessary to obtain the desired lubricating effect. However, this has the disadvantage that the leaked lubricant leads to a negative perception and can diffuse into polymer surfaces. In addition, the lubricant is consumed thereby, which leads to shorter service life and decreasing performance.

U.S. Pat. No. 7,247,587 B2 describes a nonwoven which contains a fiber mixture of fluorine-containing and non-fluorine-containing polymers combined with a thermoset as resin. The friction-reducing effect is essentially due to the low surface energy of the fluorine-containing fibers. A disadvantage of the described system is that it consists of at least 3 different components, and fluoropolymer fibers are not standard fibers, which makes the system significantly more expensive. In addition, fluorine fibers are partially crystalline and therefore comparatively hard, which reduces their lubricating effect. Fluoropolymers also have disadvantages for environmental reasons. A disadvantage of thermosets is that they are hard and brittle and can therefore be integrally formed only with difficulty onto complex geometries, such as are found, for example, in car interiors. In addition, thermosets have undesirable stick-slip behavior with high noise development.

CN 105328938 A describes a self-lubricating composite material which is a laminate body made of a woven fabric and a fluorine-containing film. A disadvantage of the composite material described is that fluoropolymers have disadvantages for environmental reasons as described above. In addition, they only have a low mechanical strength. Furthermore, the friction-reducing effect is based only on surface effects, such that it is comparatively minor. In addition, the fluorine film must have a comparatively high thickness (up to 1000 μm) in order to compensate for the lack of mechanical strength and to provide a satisfactory friction-reducing effect.

SUMMARY

In an embodiment, the present invention provides a lubricant system for reducing frictional noise, comprising: a textile fabric at least partially embedded in a lubricant, the lubricant comprising a comb polymer having a main polymer chain and a plurality of side chains covalently bonded to the main polymer chain, wherein at least one of the side chains has a molecular weight of at least 60 g/mol and/or at least 5 repeat units.

DETAILED DESCRIPTION

In an embodiment, the present invention provides a lubricant system which at least partially eliminates the aforementioned disadvantages of the prior art. In this case, the lubricant system should reduce or preferably completely eliminate frictional noises that arise when surfaces, in particular plastics, rub against one another. Moreover, an at least constant or even improved noise reduction is to be achieved in comparison to the known solutions. In addition, the lubricant system should preferably have a broad range of applications and reduce noise development, particularly preferably independently of load, speed and duration of use.

In an embodiment, the present invention provides a lubricant system comprising a textile fabric at least partially embedded in a lubricant, wherein the lubricant contains a comb polymer having a main polymer chain and a plurality of side chains covalently bonded to the main polymer chain, and wherein at least one of the side chains has a molecular weight of at least 60 g/mol and/or at least 5 repeat units.

In the lubricant system according to the invention, a textile fabric is at least partially embedded in a lubricant which contains at least one comb polymer with a main polymer chain and a plurality of side chains covalently bonded to the main polymer chain. In this case, the textile fabric is physically enclosed by the comb polymer and the lubricant is thereby prevented from leaking from the lubricant system. In addition to embedding, a chemical, for example an ionic and/or covalent, bond may also be present at least partially.

According to the invention, it was surprisingly found that the lubricant system is capable of reducing or completely eliminating frictional noise from surfaces, for example plastic surfaces, which rub against one another. Risk priority numbers (RPZ) of 1 could thus be obtained with exemplary lubricant systems according to the invention. These results could be achieved for a wide variety of friction partners, contact pressures and friction speeds. The excellent tribological properties of the lubricant system are presumably based on the lubricant being present as a noise-damping component in the form of a solid (20° C.). This is advantageous in comparison to liquid lubricants, since the noise-damping components are fixed in place and can be particularly effective as a result.

Moreover, the lubricant system can achieve an at least constant or even improved noise reduction in comparison to the known solutions. In addition, the lubricant system has a broad range of applications and is capable of reducing noise development independently of load, speed and duration of use.

The term “lubricant” is understood according to the invention to mean a substance and/or a mixture of various substances which are suitable for lubricating and/or reducing friction and wear of surfaces rubbing against each other, for example of plastic parts in the motor vehicle interior. Advantageously, the lubricant additionally serves for force transmission, cooling, vibration damping, sealing effect and prevention of corrosion.

According to the invention, the lubricant comprises a comb polymer with a main polymer chain and a plurality of side chains covalently bonded to the main polymer chain.

The term “plurality of side chains” is to be understood according to the invention as meaning that at least two repeat units of the main chain have at least one of the side chains according to the invention. The comb polymer preferably has 2 to 10000, more preferably 50 to 3000, more preferably 100 to 2000, of the side chains according to the invention. Preferably at least 10%, for example 10% to 100%, preferably 20% to 100%, more preferably 50% to 100%, in particular 80% to 100%, of the repeat units of the main chain have at least one, preferably one to two, of the side chains according to the invention. In a further preferred embodiment of the invention, [ . . . ] have [ . . . ].

The term “main polymer chain” is understood according to the invention to be the longest covalently bonded chain of atoms of a polymer. The main polymer chain preferably has a molecular weight of at least 580 g/mol, for example from 580 g/mol to 50,000 g/mol, more preferably from 1000 g/mol to 20,000 g/mol, more preferably from 1500 g/mol to 10,000 g/mol, and/or at least 8, for example 8 to 2000, preferably 25 to 1000, in particular 25 to 500, repeat units.

The term “side chain” is understood according to the invention to mean a polymer chain and/or oligomer chain which is covalently bonded to the main polymer chain, the chain length of which is shorter than that of the main polymer chain. The side chain preferably has a molecular weight of at least 60 g/mol, preferably from 60 g/mol to 2500 g/mol, preferably from 220 g/mol to 2500 g/mol, preferably from 360 g/mol to 2000 g/mol, more preferably from 450 g/mol to 1500 g/mol, more preferably from 600 g/mol to 1500 g/mol, in particular 700 g/mol to 1500 g/mol, and/or at least 5, for example 5 to 100, preferably 8 to 50, in particular 8 to 20, repeat units.

In a preferred embodiment of the invention, the main polymer chain has on average at least 3, for example 3 to 2000, preferably 10 to 1000, more preferably 50 to 500, in particular 50 to 250, side chains. In this case, different main chains may have different numbers of side chains.

Furthermore, the comb polymer, the main polymer chain and/or the side chain preferably have a glass transition temperature as measured by DSC according to DIN EN ISO 11357-2 (edition: 2014-07) at a heating rate of 10° C./minute, from −40° C. to 80° C., preferably from −20° C. to 70° C., preferably from −20° C. to 60° C., in particular −20° C. to 40° C. Rather low glass transition temperatures are advantageous in that the lubricant generally has better lubricating properties than in the case of higher glass transition temperatures.

In a preferred embodiment of the invention, the side chain of the comb polymer comprises a base oil. The term “base oil” is to be understood as meaning the customary base liquids used for the production of lubricants, in particular oils which can be assigned to the groups I, II, II+, III, IV or V in accordance with the classification of the American Petroleum Institute (API), [NLGI Spokesman, N. Samman, volume 70, number 11, pages 14 et seq.]. Particularly preferred base oils are selected from the group consisting of esters, ethers, in particular polyglycols, phenyl ethers, perfluoropolyethers, mineral oils, synthetic hydrocarbons, in particular polyalphaolefins, natural hydrocarbons, native oils and derivatives of native oils, silicone oils and/or mixtures thereof.

Particularly preferred according to the invention are esters, ethers, preferably polyglycol ethers, in particular polyphenyl ethers, polyethylene glycol ethers and/or polypropylene glycol ethers, synthetic hydrocarbons, in particular polyalphaolefins and/or mixtures thereof. Very particular preference is given to ethers, preferably polyglycol ethers, in particular polyethylene glycol ethers and/or polypropylene glycol ether.

Preferred esters are carboxylic esters, especially monoesters, diesters, triesters, tetraesters, pentaesters, polyesters, aromatic esters and mixtures thereof. The carboxylic esters preferably have a chain length of C4 to C22.

In a preferred embodiment of the invention, the base oil is selected from the group consisting of an ester of an aromatic and/or aliphatic dicarboxylic, tricarboxylic or tetracarboxylic acid having one or a mixture of C7 to C22 alcohols, of an ester of trimethylene propane, pentaerythritol or dipentaerythritol with aliphatic C7 to C22 carboxylic acids, of an ester of C18 dimer acids with C7 to C22 alcohols, complex esters, as individual components or in any mixture.

Preferred ethers are polyglycol ethers, in particular polyethylene glycol ethers and/or polypropylene glycol ethers. These ethers may be branched or unbranched. Unbranched polyglycol ethers are preferably used.

Preferred synthetic hydrocarbons are polyalphaolefins. Polyalphaolefins are generally mixtures of oligomers or polymers consisting of an a olefin or isomerized a olefin. Examples of the a olefin are 1-octene, 1-nonene, 1-decene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, 1-docosene and 1-tetradocosene. Mixtures of these substances are normally used.

In a preferred embodiment, the fluorine content, determined by elementary analysis, in the lubricant system is less than 10 wt. %, more preferably less than 5 wt. %, in particular less than 1 wt. %, based on the total weight of the lubricant system. This is possible according to the invention, since the lubricant system has excellent lubricating properties even without fluoropolymers.

The comb polymer can be obtained by polymerizing a macromonomer having polymerizable functionalities as a precursor. The term “macromonomer” is to be understood as meaning a monomer which has a molecular weight of at least 140 g/mol, for example from 140 g/mol to 2600 g/mol, preferably from 220 g/mol to 2600 g/mol, preferably from 360 g/mol to 2000 g/mol, more preferably from 450 g/mol to 1500 g/mol, more preferably 600 g/mol to 1500 g/mol, in particular 700 g/mol to 1500 g/mol. The macromonomer may have monomers of the same and/or different chemical structure. The macromonomer is preferably a base oil, in particular a base oil as defined above.

In addition to the macromonomer, other monomers, for example commercially available acrylates and/or methacrylates, can also be used to produce the comb polymer. In order to ensure polymerizability for the comb polymer, the macromonomer contains at least one polymerizable functionality. If the macromonomer at least partially contains more than one polymerizable functionality, the macromonomer can crosslink during polymerization and thus impart a higher mechanical stability to the comb polymer formed. Thus, in a preferred embodiment, the macromonomer has at least partially 2 to 10, more preferably 2 to 5, particularly preferably 2 to 3, polymerizable functionalities. Furthermore, in a further preferred embodiment, the macromonomer has at least partially 2 to 10, more preferably 2 to 5, particularly preferably 2 to 3, polymerizable functionalities and at least partially only one polymerizable functionality. For example, if one portion of the macromonomers has only one polymerizable functionality and another portion has two polymerizable functionalities, the macromonomers having two polymerizable functionalities enable crosslinking, while the macromonomers having one polymerizable functionality positively influence the lubricating properties. Various macromonomers, each of which may have different base oils and/or different polymerizable functionalities, may be used to produce the comb polymer. It was found that the good lubricating properties of the base oil can be preserved despite polymerization.

In a further preferred embodiment of the invention, the comb polymer is therefore crosslinked. The term “crosslinking” is understood according to the invention to mean the formation of a two-dimensional and/or three-dimensional network by physical and/or chemical linking of molecules. Crosslinking can take place by reaction of a main polymer chain with a main polymer chain, of a main polymer chain with a side chain, of a side chain with a side chain and/or a combination thereof. Crosslinking generally reduces the solubility of the lubricant. This is advantageous, since the mechanical stability of the lubricant can thus be increased and the risk of leakage from the textile fabric can be reduced. Crosslinking of the comb polymer thus manifests, for example, in the crosslinked comb polymer no longer being soluble in a solvent in which the macromonomer is soluble.

The macromonomer can be introduced into the textile fabric in the liquid state, as a result of which the fibers of the textile fabric can be surrounded by the macromonomer and be embedded therein. The macromonomer can be applied to one or both surfaces of the textile fabric as a coating and/or at least partially in the interior of the textile fabric, wherein the lubricant can also have a distribution gradient. Polymerizing the macromonomer results in the macromonomer hardening, whereby mechanical fixing of the textile fabric can be achieved.

Suitable polymerizable functionalities are known to the person skilled in the art. The polymerizable functionalities can preferably be polymerized by means of free-radical, ionic polymerization, polyaddition and/or polycondensation. The polymerizable functionalities are preferably polymerizable by free-radical polymerization. Particularly suitable polymerizable functionalities are selected from the group consisting of acrylamide, acrylate, methacrylate, vinyl ether, vinyl ester, (di)alkyl fumarates, (di)alkyl maleates, maleimide, styrene, alpha-olefin functionalities and combinations thereof. Particularly suitable polymerizable functionalities are acrylamide, acrylate, methacrylate and/or vinyl ether functionalities. A particularly suitable macromonomer is selected from the group consisting of ethers, in particular polyglycols and/or esters which have one or more (meth)acrylate functionalities.

In a preferred embodiment, the ratio of macromonomer functionalized with a polymerizable functionality to macromonomer functionalized with at least 2 polymerizable functionalities is preferably from 100 wt. %/1 wt. % to 1 wt. %/100 wt. %, more preferably from 98 wt. %/2 wt. % to 25 wt. %/75 wt. %, more preferably from 95 wt. %/5 wt. % to 60 wt. %/40 wt. %.

The lubricant may be present on one or both surfaces of the textile fabric as a coating and/or at least partially in the interior of the textile fabric, wherein the lubricant may also have a distribution gradient. According to the invention, the lubricant is preferably present at least partially in the interior of the textile fabric. This is advantageous since, when the lubricant system is used, for example when it is inserted between plastic surfaces in the car interior, no leakage of lubricant occurs even with continued loading and mechanical wear occurring in the process. As a result, the lubricant obtains good mechanical strength.

According to the invention, lubricant preferably does not leak in the lubricant system even at a load below room temperature at pressures of 0.1 to 1000 N/cm2.

This is advantageous, since leakage of lubricant during use degrades the lubricating effect. In addition, leaking liquid lubricants reduce the optical impression of a component and can be detected by olfactory means.

A further advantage of the lubricant system according to the invention is that a textile fabric is used instead of loose fibers, since it has a higher mechanical strength.

The term “textile fabric” is understood according to the invention to mean a fabric which is produced from textile raw materials using textile technology. Textile raw materials can be fibers, filaments, pulp and mixtures thereof. Preferred textile fabrics are woven fabrics, warp-knitted fabrics, knitted fabrics, felts, braids, nets, fibrous webs and/or nonwovens. Nonwovens are particularly preferred, since they can be produced in a simple manner with isotropic mechanical strength distribution. This is advantageous for use for minimizing noise, since the effect is not dependent on the installation direction of the lubricant system. Nonwovens can be spunbond nonwovens, meltblown nonwovens, wet nonwovens, dry nonwovens, nanofiber nonwovens and nonwovens spun from solution. In one embodiment, spunbond nonwovens are preferred, since they can be provided with a high mechanical strength by the targeted adjustment of the distribution of the fiber thicknesses. In a further embodiment, meltblown nonwovens are preferred, since they can be provided with a low fiber thickness and a very homogeneous distribution with respect to the fiber thicknesses. In a further embodiment, dry nonwovens are preferred, since they have a high tensile strength of the fibers. In a particularly preferred embodiment, the textile fabric is a wet nonwoven, since it can be produced with a very uniform fiber distribution, a low weight and a uniform thickness of the fibers.

Preferably, the textile fabric has a thickness of 15 μm to 500 μm, more preferably of 30 μm to 500 μm, more preferably of 45 μm to 200 μm, more preferably of 60 μm to 150 μm.

The textile fabric also preferably has a weight of 10 g/m2 to 500 g/m2, more preferably 35 g/m2 to 500 g/m2, more preferably 45 g/m2 to 200 g/m2, in particular 45 g/m2 to 100 g/m2.

The nonwoven, in particular in its embodiment as a wet nonwoven, may comprise staple fibers and/or short-cut fibers. According to the invention, unlike filaments that have a theoretically unlimited length, staple fibers are fibers that have a limited length, preferably of 1 mm to 80 mm, more preferably of 3 mm to 30 mm. According to the invention, short-cut fibers are fibers with a length of preferably 1 mm to 12 mm, more preferably 3 mm to 6 mm. The mean titer of the fibers may vary depending on the desired structure of the nonwoven. The use of fibers having a mean titer of 0.06 dtex to 3.3 dtex, preferably of 0.06 dtex to 1.7 dtex, preferably of 0.1 dtex to 1.0 dtex, in particular proved to be advantageous.

Practical tests have shown that the at least partial use of microfibers having a mean titer of less than 1 dtex, preferably of 0.1 dtex to 1 dtex, has an advantageous effect on the size and structure of the pore sizes and inner surface and also on the density of the nonwoven. Proportions of at least 5 wt. %, preferably of 5 wt. % to 25 wt. %, particularly preferably of 5 wt. % to 10 wt. % of microfibers, based in each case on the total amount of fibers in the nonwoven, proved to be particularly favorable. It was thus found in practical experiments that a particularly stable encapsulation of the fibers with the lubricant and thereby a particularly wear-resistant lubricating effect can be achieved with the aforementioned parameters.

The fibers can have a wide variety of shapes, for example be flat, hollow, round, oval, trilobal, multilobal, bicomponent, and/or islands-in-sea fibers. According to the invention, the cross-section of the fibers is preferably round.

According to the invention, the fibers may contain a wide variety of fiber polymers, preferably polyacrylonitrile, polyvinyl alcohol, viscose, cellulose, polyamides, in particular polyamide 6 and polyamide 6.6, polyesters, copolyesters, polyolefins, in particular polyethylene and/or polypropylene, and/or mixtures thereof. Polyesters and/or polyolefins, in particular polyethylene and/or polypropylene, are preferred.

The use of polyesters has the advantage that they have a high mechanical strength. The use of polyolefins has the advantage that they can further improve the lubricating effect of the lubricant system according to the invention based on their hydrophobic surface.

The fibers advantageously contain the aforementioned materials in a proportion of more than 50 wt. %, preferably more than 90 wt. %, more preferably 95 wt. % to 100 wt. %. Very particularly preferably, they consist of the above-mentioned materials, it being possible for the usual impurities and auxiliary agents to be present.

The fibers of the nonwoven may be in the form of matrix fibers and/or binding fibers. Binding fibers within the meaning of the invention are fibers which, for example during the production process of the nonwoven, can form solidification points and/or solidification regions at least at some intersection points of the fibers as a result of heating to a temperature above their melting point and/or softening point. At such intersection points, the binding fibers can form firmly bonded connections to other fibers and/or to themselves. The use of binding fibers thus makes it possible to construct a framework and to obtain a thermally solidified nonwoven. Alternatively, the binding fibers can also melt completely and solidify the nonwoven in this way. The binding fibers can be formed as core-sheath fibers, in which the sheath constitutes the binding component, and/or as non-drawn fibers.

Matrix fibers within the meaning of the invention are fibers which, unlike binding fibers, are present in a significantly clearer fiber form. An advantage of the presence of the matrix fibers is that the stability of the fabric as a whole can be increased.

In a preferred embodiment of the invention, the ratio between lubricant and textile fabric in the lubricant system is 1 wt. % to 1000 wt. %, preferably 1 wt. % to 500 wt. %, more preferably 10 wt. % to 200 wt. %, more preferably 80 wt. % to 160 wt. %, based in each case on the weight of the textile fabric. It was found that a good lubricating effect with good mechanical adaptability can be achieved with these ratios.

In a further preferred embodiment of the invention, the weight of the lubricant system, measured according to test specification DIN EN 29073, is from 15 g/m2 to 600 g/m2, more preferably from 50 g/m2 to 300 g/m2, more preferably from 50 g/m2 to 180 g/m2.

In a further preferred embodiment of the invention, the thickness of the lubricant system, measured according to test specification EN 29073-T2, is from 15 μm to 600 μm, more preferably from 50 μm to 600 μm, more preferably from 60 μm to 500 μm, more preferably from 60 μm to 300 μm.

It was surprisingly found according to the invention that a good lubricating effect can be achieved even at low thicknesses. This is advantageous when used in the car interior, for example for optical reasons. Furthermore, the small thickness is advantageous in that mechanical loads can be minimized as a result.

The lubricant system according to the invention preferably has pores at least partially. The pores may be open or closed pores. The proportion of open pores can be determined by air permeability measurements. In a preferred embodiment of the invention, the air permeability of the lubricant system, measured according to test specification DIN EN ISO 9237, is 0 l/m2*s to 1000 l/m2*s, more preferably 10 l/m2*s to 500 l/m2*s, more preferably 25 l/m2*s to 300 l/m2*s.

The pores are advantageous, since they provide the lubricant system with an uneven surface. As a result, the surface has a smaller number of frictional contacts than a smooth surface, which in turn leads to a lower static friction. The uneven surface has a plurality of small frictional contacts, which in turn results in lower static friction than a very large frictional contact in the case of a smooth surface.

In a further embodiment of the invention, the lubricant system according to the invention is single-layered, i.e., there are no physical phase boundaries within the lubricant system. This is advantageous, since no components that are inoperable for the lubricating effect are used in this way.

In a preferred embodiment of the invention, the lubricant system is equipped on at least one side with an adhesive layer, for example a polyacrylate and/or natural rubber.

The lubricant system according to the invention has excellent frictional-noise-reducing properties. Thus, in one embodiment of the invention, the risk priority number of the lubricant system with a plastic as friction partner, measured according to the VDA 203-206 standard at a speed of 1 mm/s to 10 mm/s and a normal force of 5 N to 20 N, is 1 to 5, preferably 1 to 3, more preferably 1 to 2.

In a further preferred embodiment of the invention, the risk priority number of the lubricant system with a polycarbonate/acrylonitrile butadiene styrene copolymer (PC/ABS) blend as friction partner, measured according to the VDA 203-206 standard at a speed of 1 mm/s to 10 mm/s and a normal force of 5 N to 20 N, is 1 to 5, more preferably 1 to 3, in particular 1 to 2.

In a further preferred embodiment of the invention, the risk priority number of the lubricant system with polyurethane (Beneron®) as friction partner, measured according to the VDA 203-206 standard at a speed of 1 mm/s to 10 mm/s and a normal force of 5 N to 20 N, is 1 to 5, more preferably 1 to 3, in particular 1 to 2.

The lubricant may exclusively consist of the comb polymer. However, the lubricant preferably contains customary additives, such as anticorrosion additives, metal deactivators, antiwear additives and/or ion complexing agents.

The lubricant may furthermore contain solid lubricants. In principle, the lubricant may contain thickeners. However, they can be dispensed with based on the use of the comparatively viscous comb polymer. The proportion of thickeners, in particular of metal soaps, metal complex soaps, bentonites, ureas, silicates, sulfonates, polyimides, is preferably less than 20 wt. %, more preferably less than 10 wt %, in particular less than 2 wt. %.

The proportion of comb polymer in the lubricant is preferably 30 wt. %. to 100 wt. %, more preferably 75 wt. % to 100 wt. %, in particular 90 wt. % to 100 wt. %.

The invention further relates to a method for producing a lubricant system comprising a textile fabric embedded in a lubricant, comprising the following method steps:

    • 1. Providing a textile fabric;
    • 2. Impregnating and/or coating the textile fabric with a macromonomer-containing coating composition, the macromonomer having a molecular weight of at least 140 g/mol, for example of 140 g/mol to 2600, preferably of 220 g/mol to 2600 g/mol, preferably of 360 g/mol to 2000 g/mol, more preferably of 450 g/mol to 1500 g/mol, more preferably of 600 g/mol to 1500 g/mol, in particular of 700 g/mol to 1500 g/mol;
    • 3. Polymerizing the macromonomer to form a comb polymer having a main polymer chain and a plurality of side chains covalently bonded to the main polymer chain, at least one of the side chains having a molecular weight of at least 60 g/mol, for example 60 g/mol to 2500 g/mol , preferably 220 g/mol to 2500 g/mol, preferably 360 g/mol to 2000 g/mol, more preferably 450 g/mol to 1500 g/mol, more preferably 600 g/mol to 1500 g/mol, in particular 700 g/mol to 1500 g/mol, with a lubricant being formed in which the textile fabric is embedded, forming the lubricant system.

Preferred features, such as especially preferred macromonomer, textile fabrics and further components of the lubricant system, are those described within the scope of the invention with regard to the lubricant system according to the invention.

The macromonomer used in impregnation and/or coating has a molecular weight of at least 140 g/mol, preferably 140 g/mol to 2600 g/mol, preferably 220 g/mol to 2600 g/mol, preferably 360 g/mol to 2000 g/mol, more preferably 450 g/mol to 1500 g/mol, more preferably 600 g/mol to 1500 g/mol, in particular 700 g/mol to 1500 g/mol. The macromonomer may have monomers of the same and/or different chemical structure. The macromonomer is preferably a base oil, in particular a functionalized base oil as defined above.

In addition to the macromonomer, other monomers, for example commercially available acrylates and/or methacrylates, can also be used to produce the comb polymer. In order to ensure polymerizability to the comb polymer, the macromonomer has at least one polymerizable functionality. Suitable polymerizable functionalities are those mentioned above in relation to the lubricant system. If the macromonomer at least partially contains more than one polymerizable functionality, the macromonomer can crosslink during polymerization and thus impart a higher mechanical stability to the comb polymer formed. Thus, in a preferred embodiment, the macromonomer has at least partially 2 to 10, more preferably 2 to 5, particularly preferably 2 to 3, polymerizable functionalities. Various macromonomers respectively selected from different base oils, which may be functionalized with different polymerizable functionalities, may be used to produce the comb polymer.

In a preferred embodiment, the ratio of the macromonomer functionalized with one polymerizable functionality to the macromonomer functionalized with at least 2 polymerizable functionalities, is preferably 100 wt. %/1 wt. % to 1 wt. %/100 wt. %, more preferably from 98 wt. %/2 wt. % to 25 wt. %/75 wt. %, more preferably from 95 wt. %/5 wt. % to 60 wt. %/40 wt. %.

The coating composition can be applied to one or both surfaces of the textile fabric as a coating and/or at least partially in the interior of the textile fabric, wherein the coating composition can also have a distribution gradient.

The coating composition may exclusively consist of the macromonomer. However, the coating composition preferably contains customary additives, such as anticorrosion additives, metal deactivators, antiwear additives and/or ion complexing agents.

The coating composition can also contain solid lubricants. In principle, the coating composition may contain thickeners. However, they can be dispensed with based on the use of the comparatively viscous macromonomer. The proportion of thickeners, in particular of metal soaps, metal complex soaps, bentonites, ureas, silicates, sulfonates, polyimides, is preferably less than 20 wt. %, more preferably less than 10 wt %, in particular less than 2 wt. %.

The proportion of macromonomer in the coating composition is preferably 50 wt. %. to 100 wt. % and/or 50 wt. % to 90 wt. %, more preferably 75 wt. % to 100 wt. % and/or 75 wt. % to 90 wt. %, in particular 80 wt. % to 100 wt. % and/or 80 wt. % to 90 wt. %.

The coating composition may also contain suitable solvents, for example water.

The impregnation and/or coating of the textile fabric can be carried out in a conventional manner. Preferred are roll coating methods, padding, dip coating methods, spray coating methods, slot die coating methods, and/or combinations thereof.

Polymerization of the macromonomer can also be carried out in a conventional manner. The macromonomer is preferably polymerized and optionally crosslinked by means of free-radical, ionic polymerization, polyaddition and/or polycondensation.

Radiation-induced crosslinking methods are particularly preferred.

Subsequent to the polymerization, a drying step may be carried out, preferably at temperatures greater than 30° C., more preferably greater than 80° C.

The lubricant system can furthermore be equipped on at least one side with an adhesive layer, for example a polyacrylate and/or natural rubber.

A further subject matter of the present invention is the use of the lubricant system for reducing frictional noise, in particular from components exposed to frictional loads in the car interior, such as instrument panels with fittings, door trim with operating elements. In addition, the lubricant system can also be used to reduce frictional noise from moving cables, for example in aviation. The lubricant system is preferably introduced between the respective friction partners. In a preferred embodiment, the lubricant system is used simultaneously for reducing frictional noise and for sealing, for example, dynamically loaded components.

In the context of the present invention, the following measurement methods were used:

The weight of the nonwoven was measured according to test specification DIN EN 29073.

The thickness of the nonwovens according to the invention was measured according to test specification EN 29073-T2.

The invention is explained in more detail with reference to the following examples.

EXAMPLE 1 Production of a Lubricant System According to the Invention

APP wet nonwoven (weight: 50 g/m2; thickness 0.12 mm) is treated with a solution consisting of a mixture of two crosslinkable base oils, namely 211 g of a methacrylate-functionalized polyethylene glycol (PEG) (Mn PEG: 308 g/mol) and 12.5 g of a PEG diacrylate (Mn PEG: 250 g/mol), 22.8 g of water and 2.5 g of a commercially available UV radical initiator and irradiated for crosslinking with UV light for 45 seconds. The resulting nonwoven has the crosslinked base oils in the interior and on its surface. The nonwoven is then washed in a water bath and dried at 100° C. A lubricant system according to the invention having a thickness of 0.89 mm and a weight of 121.9 g/m2 is obtained. The ratio between lubricant and textile fabric in this case is (121.9 g/m2-50 g/m2)/50 g/m2=1.438, or 143.8 wt. % of the textile fabric.

EXAMPLE 2 Production of a Lubricant System According to the Invention

A PP wet nonwoven (weight: 50 g/m2; thickness 0.12 mm) is coated with a solution consisting of a mixture of two crosslinkable base oils, namely 67.5 g of an acrylate-functionalized polyethylene glycol (Mn PEG: 350 g/mol) and 10 g of a PEG diacrylate (Mn PEG: 200 g/mol), 166.3 g of water and 5.1 g of a commercially available UV radical initiator and irradiated for crosslinking with UV light for 45 seconds. The resulting nonwoven has the crosslinked base oils in the interior and on its surface. The nonwoven is then washed in a water bath and dried at 100° C. A lubricant system according to the invention having a thickness of 0.121 mm and a weight of 99.1 g/m2 is obtained. The ratio between lubricant and textile fabric in this case is (99.1 g/m2-50 g/m2)/50 g/m2=0.982, or 98.2 wt. % of the textile fabric.

EXAMPLE 3 Production of a Lubricant System According to the Invention

A PP wet nonwoven (weight: 50 g/m2; thickness 0.1 mm) is coated with a solution consisting of a mixture of two crosslinkable base oils, namely 211 g of a methacrylate-functionalized polyethylene glycol (Mn PEG: 750 g/mol) and 12.5 g of a PEG diacrylate (Mn PEG: 400 g/mol), 99 g of water and 2.0 g of a commercially available UV radical initiator and irradiated for crosslinking with UV light for 45 seconds. The resulting nonwoven has the crosslinked base oils in the interior and on its surface. The nonwoven is then washed in a water bath and dried at 100° C. A lubricant system according to the invention having a thickness of 0.117 mm and a weight of 99.2 g/m2 is obtained. The ratio between lubricant and textile fabric in this case is (99.2 g/m2-50 g/m2)/50 g/m2=0.984, or 98.4 wt. % of the textile fabric.

EXAMPLE 4 Production of a Lubricant System According to the Invention

A PP wet nonwoven (weight: 57.3 g/m2; thickness 0.105 mm) is coated with a solution consisting of a mixture of two crosslinkable base oils, namely 1387.5 g of a methacrylate-functionalized polyethylene glycol (Mn PEG: 818 g/mol) and 150 g of an N,N-methylene-diacrylamide (Mn: 224 g/mol), 1387.5 g of water and 60 g of a commercially available UV radical initiator, e.g. Irgacure 369®, and irradiated for crosslinking with UV light for 45 seconds. The resulting nonwoven has the crosslinked base oils in the interior and on its surface. The nonwoven is then washed in a water bath and dried at 100° C. A lubricant system according to the invention having a thickness of 0.117 mm and a weight of 86.5 g/m2 is obtained.

COMPARATIVE EXAMPLE 5 Production of a Lubricant System not According to the Invention

A PET wet nonwoven (weight 85 g/m2, thickness 0.12 mm) is coated with a 50% aqueous dispersion of a polyurethane acrylate and dried at 120° C. The polyurethane acrylate is not a comb polymer which has at least one side chain with a molecular weight of at least 60 g/mol and/or at least 5 repeat units. Rather, the side chains preferably have a molecular weight of 500 to 1000 g/mol. During drying, thermal crosslinking of the polyurethane acrylate occurs. A coated nonwoven having a thickness of 0.128 mm and a weight of 145 g/m2 is obtained.

EXAMPLE 6 Determination of Relevant Parameters of the Lubricant Systems and Comparison with Commercial Lubricant Systems

The thicknesses, weights and RPZ numbers of the aforementioned lubricant systems according to the invention (Examples 1 to 4) are determined and compared with the following commercial, lubricant systems not according to the invention:

    • tesa® 51608
    • tesa® 51616
    • 3M Conformable Sound Management Film 9343 (3M 9343)

TABLE 1 OVERVIEW OF THE WEIGHTS AND THICKNESSES OF THE VARIOUS LUBRICATION SYSTEMS Weight (g/m2) Thickness (mm) Example 1 121.9 0.89 Example 2 99.1 0.104 Example 3 99.2 0.117 Example 4 86.5 0.117 Comparative Example 5 145 0.128 tesa ® 51608 0.28 tesa ® 51616 0.65 3M 9343 0.58

The aforementioned lubricant systems according to the invention and comparative examples are evaluated with the aid of the SSP-04 stick-slip test bench from Zins-Ziegler by determining their RPZ numbers. Testing is carried out according to the VDA 203-206 standard.

The RPZ represents the stick-slip tendency on a scale of 1-10 and describes the tendency of a material pairing to stick-slip at a predetermined normal force and a defined speed. Stick-slip is the English term for sliding in a jerking motion. It describes the periodic change between adhesion and tear-off of two material surfaces moving over each other. It is, for example, the cause of noise phenomena, such as creaking or squeaking. For the evaluation of a material pairing, an RPZ between 1 and 3 is considered to be non-critical, at 4 or 5 to be still acceptable. With an RPZ of 6 to 10, the solution to the problem is to be regarded as not given. Unless stated otherwise, the definition of the test standard applies. Tensile bars of two materials were selected as friction partners for the examples and comparative examples: PC-ABS and Beneron®.

TABLE 2 OVERVIEW OF THE RPZS OBTAINED IN MEASUREMENTS AGAINST PC-ABS Measured parameters Normal Example Example Example Example Comparative Tesa Tesa 3M Speed force 1 2 3 4 Example 5 51608 51616 9343 1 mm/s  5N 1 1 1 1 3 1 2 2 5 mm/s  5N 1 1 1 1 4 1 2 2 10 mm/s  5N 1 1 1 1 5 1 3 2 1 mm/s 10N 1 1 1 1 4 2 2 2 5 mm/s 10N 1 1 1 1 5 2 2 1 10 mm/s 10N 1 1 1 1 3 2 3 1 1 mm/s 20N 1 1 1 1 3 2 2 2 5 mm/s 20N 1 1 1 1 4 2 1 1 10 mm/s 20N 1 1 1 1 4 2 3 1

It can be seen from Table 2 that Examples 1 to 4 according to the invention result in excellent RPZ values at all measured speeds and normal forces. In contrast, Comparative Example 5, which does not include a comb polymer-containing lubricant, exhibits significantly worse RPZ values at all measured speeds and normal forces. The commercial products also show worse RPZ values at least at some measured speeds and normal forces.

TABLE 3 OVERVIEW OF THE RPZS OBTAINED IN MEASUREMENTS AGAINST BENERON ® Measured parameters Normal Example Example Example Example Comparison Tesa Tesa 3M Speed force 1 2 3 4 Example 5 51608 51616 9343 1 mm/s  5N 1 1 1 2 4 3 2 7 5 mm/s  5N 1 2 2 2 7 7 1 5 10 mm/s  5N 1 2 2 3 5 4 1 3 1 mm/s 10N 1 1 2 2 4 6 2 7 5 mm/s 10N 1 2 2 2 6 7 3 5 10 mm/s 10N 1 2 2 3 7 6 1 4 1 mm/s 20N 1 1 1 2 4 5 2 4 5 mm/s 20N 1 2 2 2 6 4 1 1 10 mm/s 20N 1 2 2 2 5 3 1 1

It can be seen from Table 3 that Examples 1 to 4 according to the invention also result in very good RPZ values with respect to Beneron® as friction partner at all measured speeds and normal forces. The values which are slightly worsened compared to Table 2 are presumably based on the fact that Beneron® as friction partner has a higher static friction. Furthermore, it is found that Examples 1 to 4 according to the invention have uniformly low RPZ values, and that surprisingly almost independently of speed and normal force. On the other hand, the commercial products show an RPZ of 1 or 2 only under certain conditions. This is particularly remarkable, since comparative examples 3M 9343 and tesa 51616 have more than twice or five times the thickness. Moreover, comparative example Tesa 51608, which is more than twice as thick as the examples according to the invention, shows significantly worse RPZ values.

EXAMPLE 6 Determination of the Service Life of a Lubricant System According to the Invention and Comparison with a Commercial Lubricant System

The test carried out in Example 5 on a stick-slip test bench from Zins-Ziegler was used to determine the long-term stability of the lubricant system according to the invention at a simulated service performance of a car of 60000 km service performance in comparison to the commercial lubricant system tesa 51616 not according to the invention. For this purpose, the RPZs are determined after 0 km, 20000 km, 40000 km, 60000 km. The RPZ given here is the mean of the RPZs at the measured parameters given in Example 5 (speed, normal force).

0 km 20000 km 40000 km 60000 km Example 4 1.0 2.4 2.7 2.9 Tesa 51616 3.4 3.7 4.3 4.3

While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. It will be understood that changes and modifications may be made by those of ordinary skill within the scope of the following claims. In particular, the present invention covers further embodiments with any combination of features from different embodiments described above and below. Additionally, statements made herein characterizing the invention refer to an embodiment of the invention and not necessarily all embodiments.

The terms used in the claims should be construed to have the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the article “a” or “the” in introducing an element should not be interpreted as being exclusive of a plurality of elements. Likewise, the recitation of “or” should be interpreted as being inclusive, such that the recitation of “A or B” is not exclusive of “A and B,” unless it is clear from the context or the foregoing description that only one of A and B is intended. Further, the recitation of “at least one of A, B and C” should be interpreted as one or more of a group of elements consisting of A, B and C, and should not be interpreted as requiring at least one of each of the listed elements A, B and C, regardless of whether A, B and C are related as categories or otherwise. Moreover, the recitation of “A, B and/or C” or “at least one of A, B or C” should be interpreted as including any singular entity from the listed elements, e.g., A, any subset from the listed elements, e.g., A and B, or the entire list of elements A, B and C.

Claims

1. A lubricant system for reducing frictional noise, comprising:

a textile fabric at least partially embedded in a lubricant, the lubricant comprising a comb polymer having a main polymer chain and a plurality of side chains covalently bonded to the main polymer chain,
wherein at least one of the side chains has a molecular weight of at least 60 g/mol and/or at least 5 repeat units.

2. The lubricant system according to claim 1, wherein the textile fabric is physically enclosed by the comb polymer.

3. The lubricant system according to claim 1, wherein the comb polymer is at least partially chemically bonded to the textile fabric.

4. The lubricant system according to claim 1, wherein the lubricant is present as a solid at 20° C.

5. The lubricant system according to claim 1, wherein at least 10% of the repeat units of the main chain comprise at least one of the side chains.

6. The lubricant system according to claim 1, wherein the main polymer chain has a molecular weight of at least 580 g/mol, and/or at least 8 repeat units.

7. The lubricant system according to claim 1, wherein the side chain has a molecular weight of at least 220 g/mol, and/or at least 5 repeat units.

8. The lubricant system according to claim 1, wherein the side chain of the comb polymer comprises a base oil.

9. The lubricant system according to claim 1, wherein the comb polymer is obtained by polymerizing macromonomer having polymerizable functionalities, the macromonomer having at least partially more than one polymerizable functionality.

10. The lubricant system according to claim 9, wherein the polymerizable functionalities are selected from the group consisting of acrylamide, acrylate, methacrylate, and/or vinyl ether functionalities.

11. The lubricant system according to claim 1, wherein the comb polymer is present in crosslinked form.

12. The lubricant system according to claim 1, wherein the textile fabric comprises a wet nonwoven.

13. The lubricant system according to claim 1, wherein the lubricant system has a thickness of from 60 μm to 300 μm and/or a weight of 50 g/m2 to 300 g/m2.

14. The lubricant system according to claim 1, wherein the textile fabric contains polyolefin fibers and/or polyester fibers in a proportion of 50 wt. % to 100 wt. %, based in each case on a total weight of the textile fabric.

15. The lubricant system according to claim 1, wherein a proportion of comb polymer in the lubricant is 30 wt. % to 100 wt. %.

16. A method for producing the lubricant system according to claim 1, comprising a textile fabric at least partially embedded in a lubricant, comprising the following method steps:

providing a textile fabric;
impregnating and/or coating the textile fabric with a macromonomer-containing coating composition, the macromonomer having a molecular weight of at least 140 g/mol; and
polymerizing the macromonomer to form a comb polymer having a main polymer chain and a plurality of side chains covalently bonded to the main polymer chain, at least one of the side chains having a molecular weight of at least 60 g/mol, with a lubricant being formed in which the textile fabric is embedded, forming the lubricant system.

17. A method of using the lubricant system according to claim 1, comprising:

using the lubricant system to reduce frictional noise from components exposed to frictional loads in a car interior.

18. The lubricant system according to claim 3, wherein chemically bonded comprises ionically and/or covalently bonded.

19. The lubricant system according to claim 5, wherein 80% to 100% of the repeat units of the main chain comprise at least one of the side chains.

20. The lubricant system according to claim 6, wherein the main polymer chain has a molecular weight of 580 g/mol to 50,000 g/mol, and/or 8 to 2000 repeat units.

Patent History
Publication number: 20200190424
Type: Application
Filed: Dec 11, 2019
Publication Date: Jun 18, 2020
Inventors: Wolfgang Brenner (Neustadt), Michael Roth (Mainz), Frank Werner (Munich), Stefan Seemeyer (Wolfratshausen), Thomas Kilthau (Geretsried)
Application Number: 16/709,957
Classifications
International Classification: C10M 169/04 (20060101);