Patent Application
20120309573
The invention relates to a drive belt with a base made of a polymeric material with elastic properties, comprising an outer layer as belt backing and a substructure with a force-transmission zone, where
Drive belts, which are also called force-transmission belts and which in the operating condition are mostly continuous belts, can take the form of flat belts, V-belts, V-ribbed belts, toothed belts, and clutch belts. V-ribbed belts and toothed belts are particularly important, and in this connection reference is made to the following patent literature:
In order to achieve the elasticity of a drive belt, the base, and therefore the outer layer and the substructure, are composed of a polymeric material with elastic properties, and particular mention may be made here of the following two groups of materials: elastomers and thermoplastic elastomers. Elastomers based on a vulcanized rubber mixture are particularly important.
In one of the three variants mentioned in the introduction, the drive belt has at least one embedded tension member running in the longitudinal direction of the belt, and in particular here a plurality of tension members form a reinforcement layer or tensile layer. A tension member constructed as a cord is particularly important here, and the prior art gives various ideas for relevant materials. The significant types of materials are: steel, polyamide (PA), aramid, polyester, glass fibers, carbon fibers, basalt, polyether ether ketone (PEEK), polyethylene tereph-thalate (PET), and polyethylene 2,6-naphthalate (PEN). The tension member moreover has mostly been prepared with an adhesive system, for example with a resorcinol-formaldehyde latex (RFL), thus ensuring long-term effectiveness of adhesion to the surrounding polymeric material in one of the three variants mentioned in the introduction.
In particular the force-transmission zone of a drive belt has an abrasion-resistant coating, which additionally serves for noise-reduction and moreover also can have been rendered oil-resistant. The following are used here: a flock covering, in particular in the form of a cotton flock or of an aramid flock, a thin fiber-filled (for example, aramid-fiber-filled) elastic polymer layer, a textile covering, in particular in the form of a woven fabric, a warp-knitted fabric or a weft-knitted fabric, or a foil (for example, PTFE foil), or a foil composite (for example, PA PTFE foil). In respect of the relevant prior art, particular reference is made to the following patent literature:
The coating is mostly prepared on the side that has contact with the base of the drive belt, in particular with the substructure thereof, in a manner that promotes adhesion, for example by using RFL.
Developments in the field of drive belts have hitherto focused on the provision of low-noise coatings that are also abrasion-resistant, and also on the search for high-performance tension members and polymer materials.
For many products, such as household equipment, electric-powered tools, and garden equipment, there is now an increasing demand for use of materials having low pollutant content, in particular no pollutant content. In the case of polymer mixtures with applications in vehicle construction, this development work has hitherto focused on ensuring that polymer materials have low N-nitrosamine content, in particular no N-nitrosamine content.
With a view to further development, the object of the invention now consists in providing drive belts which have low pollutant content, in particular no pollutant content, and which moreover can be used without reservations in applications involving body contact.
The object is achieved in that at least the outer layer and/or the substructure is/are free from carbon black and free from polycyclic aromatic hydrocarbons (PAHs).
In the second or third variant, it is advantageous that the outer layer and the substructure, and also the intermediate layer, are free from carbon black and PAH-free. The polymer mixtures comprise by way of example silica in place of the carbon black filler which intrinsically mostly comprises PAH. The mineral-oil-based plasticizer, which likewise mostly comprises PAH, is replaced by an appropriate PAH-free plasticizer.
Since the side on which the tension member and the abrasion-resistant coating are in contact with the base has mostly been prepared with an adhesive system, it is preferable to use an adhesive system which is likewise free from carbon black and PAH-free.
The drive belt is preferably free from further pollutants, in particular free from chlorine or from any chlorine-containing substance. In particular, chloroprene rubber (CR) is avoided here.
In respect of the adhesive system for the abrasion-resistant coating, use of the following variants is preferred:
The adhesive system for the abrasion-resistant coating can also have a dye. An advantage of the RFL-free adhesive system is that it is colorless, and it is therefore possible by way of example to color the woven as desired. It is also possible to incorporate a dye by mixing into the polymer mixture of the outer layer and/or of the substructure, since carbon black filler is avoided here.
A toothed belt of the prior art (Table 1) is compared with a PAH-free toothed belt of the invention (Table 2) on the basis of a mixing formulation, specifically supplemented by a comparison of different adhesive systems. Both toothed belts had a tension member arrangement of the first variant.
Other advantageous possibilities for design of the drive belt of the invention are presented in still more detail in conjunction with the description of the figures.
The invention will now be described with reference to the drawings wherein:
The outer layer 2 and the substructure 4 here, as overall unit, form the base made of a polymeric material with elastic properties, in particular taking the form of a vulcanized rubber mixture, comprising at least one rubber component and mixture ingredients. Rubber component used in particular comprises ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), (partially) hydrogenated nitrile rubber (HNBR), fluororubber (FKM), natural rubber (NR), styrene-butadiene rubber (SBR) or butadiene rubber (BR), which are used in unblended form or a form blended with at least one further rubber component, in particular with one of the abovementioned types of rubber, for example taking the form of a EPM/EPDM blend or SBR/BR blend. HNBR, EPM, EPDM or an EPM/EPDM blend is particularly important here. The mixture ingredients comprise at least one crosslinking agent or one crosslinking agent system (crosslinking agent and accelerator). Further mixture ingredients are mostly also a filler and/or a processing aid and/or a plasticizer and/or an antioxidant, and also optionally further additives, such as fibers for increasing the strength, and color pigments. In this connection, reference is made to the general state of rubber mixture technology.
The rubber mixture is free from carbon black and PAH-free, and specifically with simultaneous avoidance of CR as rubber component.
The tension members 3 here have been embedded in the base without any intermediate layer. Each cord-structure tension member is composed of a filament material, for example of glass filaments. For a toothed belt in an oil environment, lang-lay cords are better here than normal reverse-lay cords. Further measures relating to the tension member are explained in still more detail in conjunction with
In particular the substructure 4 of the drive belt 1 can moreover comprise fibers uniformly distributed, in particular textile fibers. The fibers are composed of cotton, cellulose, aramid, in particular p-aramid, polyamide, in particular PA6 or PA.6.6, polyvinyl acetal (PVA) or polyethylene terephthalate (PET). The fibers can take the form of a pulp (fiber slurry) or short fibers. In the case of short fibers, the length is ≦8 mm, in particular ≦6 mm.
The force-transmission zone 7 of the drive belt 1 is particularly susceptible to wear due to abrasion, heat, and the effect of oils. For this reason, the force-transmission zone has a coating in the form of a textile covering 8, for example taking the form of a woven or knit. The textile covering can by way of example additionally have been saturated, as in the teaching of document WO 2005/080821 A1, with a fluorine-containing plastic which in particular is polytetrafluoroethylene (PTFE), and specifically with a high fill level of the plastic, where a polymer coating (seal) is simultaneously formed at additional oil-resistant protective layer 9. The two sublayers 8 and 9 with different functions appear here as combined protective layer.
The outer layer 2 of the drive belt 1 can also have a coating, for example in the manner described above.
The drive belt 1 in its particular embodiment as toothed belt is particularly suitable for driving an oil pump of an engine, for example of a motor-vehicle engine.
The filaments 11 are composed by way of example of glass. This means that the strands 10 and finally the cord in the form of effective tension member 3 (
The filaments 11, the strands 10 or the cord can have been prepared. The cord is often prepared in a manner that promotes adhesion, for example by using RFL. It is particularly advantageous to pre-prepare the filaments 11, thus forming prepared strands 10, and finally also a prepared cord. The preparation of the filaments is achieved here in particular with a vinylpyridine RFL to form a filament sheath.
It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2010 016 393.7 | Apr 2010 | DE | national |
This application is a continuation application of international patent application PCT/EP 2011/051429, filed Feb. 2, 2011, designating the United States and claiming priority from German application 10 2010 016 393.7, filed Apr. 12, 2010, and the entire content of both applications is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2011/051429 | Feb 2011 | US |
| Child | 13557956 | US |
