Mixing polyurethane-based power conveyor belt as well as composition and production method thereof

Abstract

A composition suitable for a material layer of a power transmission belt is described. The composition includes a kneadable polyurethane, such as a polyester-based kneadable polyurethane or a polyether-based kneadable polyurethane, such that a material layer formed from the composition is solid but flexible. The disclosed material layers may be applied to form the body portion of power conveyor belts, such as synchronous belts, V-belts, and micro-V-belts.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 276,330, filed on November 5, 2021, entitled "Mixable Polyurethane-Based Power Transmission Belts, Compositions and Production Methods Thereof," the entire text of which is incorporated herein by reference. Background Art

[0003] There are many different types of power transmission belts, including but not limited to synchronous belts, V-belts and micro-V-belts. One feature common to many types of power transmission belts is that the main body of the belt is made of polyurethane elastomeric material, including ribs or teeth that may be formed therein.

[0004] Typically, the polyurethane materials used in the production of power transmission belts are castable (i.e., liquid) polyurethane compositions. Therefore, the production of power transmission belts typically requires injection molding process steps and related equipment. In these process steps, liquid polyurethane is injected into a mold or die for the base portion of the belt having the desired shape and / or surface features (such as teeth or ribs), and the material is subsequently cured to harden the material to the shape of the mold or die. The molded material can then be removed from the mold or die and combined with other components of the belt, such as a backing layer and a surface layer.

[0005] In the production of various types of power transmission belts, the equipment required for the injection molding step can be highly specialized and therefore expensive. The cost of the specialized equipment required to perform the injection molding process step often limits the number of machines a manufacturer is willing to invest in. This can limit the total production of power transmission belts and the number of locations where power transmission belts can be produced. That is, since it is often too costly to distribute machines on a large scale over a larger area, the production of power transmission belts is more likely to be highly regionalized or localized. All of these factors result in the production cost of power transmission belts being generally higher than other production processes that use less expensive and more widely distributed machines.

[0006] Another problem associated with the use of castable polyurethanes in the production of power transmission belts is the difficult processing nature of the castable polyurethane material. Because castable polyurethanes are generally liquids, and the difficulty in handling and generally controlling liquid materials presents many complications during the production process.

[0007] Thus, there remains a need for improved materials and production methods in the field of power transmission belts. Summary of the invention

[0008] The present invention summary is provided to introduce some concepts, and these concepts will be further described in the following detailed description. The present invention summary and the previous background technology section are not used to determine the key aspects or essential aspects of the required subject matter. In addition, the present invention summary is not used to assist in determining the scope of the required subject matter.

[0009] In some embodiments, the power transmission belt includes a main body portion to which a plurality of surface features such as ribs or teeth may be molded. The composition of the main body portion comprises a remixable polyurethane, such as a polyester-based remixable polyurethane or a polyether-based remixable polyurethane. The power transmission belt may be, for example, a synchronous belt, a V-belt, or a micro-V-belt.

[0010] In some embodiments, a method for producing a power transmission belt is described, comprising the steps of constructing a plurality of layers of thick sheets on a first mold portion, encapsulating the plurality of layers with a second mold portion disposed on the first mold portion, and applying heat and / or pressure to the plurality of layers disposed in the mold to mold the plurality of layers together and form a plurality of surface features on an upper surface or a lower surface of the plurality of layers. At least one of the plurality of layers is a main body material layer, the main body material comprising a remixable polyurethane. The remixable polyurethane may be a polyester-based remixable polyurethane or a polyether-based remixable polyurethane.

[0011] In some embodiments, a millable polyurethane composition suitable for preparing a power transmission body portion material sheet includes a polyether-based or polyester-based millable polyurethane, optionally at least one additional elastomer, a curing agent, and a reinforcing filler dispersed throughout the composition.

[0012] After considering the detailed description and drawings of this article, various aspects of the technology described herein will become apparent. However, it should be understood that the scope of the claimed subject matter should be determined by the disclosed claims, rather than by whether the given subject matter solves any or all of the problems described in the background section, nor does it include any features or aspects described in the summary section. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Non-limiting and non-exhaustive embodiments of the disclosed technology, including preferred embodiments, are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various figures unless otherwise specified.

[0014] Figure 1 is a cross-sectional perspective view of a timing belt including a body portion having the composition of various embodiments described herein.

[0015] Figure 2 The flowchart of FIG. 1 depicts a method of producing a power transmission belt according to various embodiments described herein. DETAILED DESCRIPTION

[0016] The embodiments will be described more fully below with reference to the accompanying drawings, which form a part of the present invention and provide specific exemplary embodiments as examples. These embodiments are disclosed in sufficient detail so that those skilled in the art can practice the invention. However, the embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments described herein. Therefore, the following detailed description is non-limiting.

[0017] Reference Figure 1 , which describes one embodiment of a timing belt 100. The belt 100 generally includes a body portion 110, which may be made entirely of the same material. The body portion 110 includes a surface feature 111 formed on the surface of the body portion 110, such as by molding a generally flat surface of the body portion 100 during the production process of the belt 100 to form the shaped surface feature 111 in the body portion 110. Figure 1 In the embodiment of the present invention, the surface features 111 are generally in the form of teeth oriented perpendicular to the direction of travel of the belt 100. However, it should be understood that the specific shape, size and orientation of the surface features 111 are not limited. For example, the surface features 111 can be formed in the main body portion 110 so that they are oriented parallel to the direction of travel of the belt 100, in which case the surface features 111 are generally ribs.

[0018] Also like Figure 1 As shown, a plurality of tension cords 112 are embedded in the main body portion 110. The tension cords 112 are generally oriented parallel to the travel direction of the belt 100, and parameters such as the winding angle, winding tension, and spacing between adjacent windings of the cords 112 can be adjusted, for example, according to the requirements of the finished product. The material of the cords 112 is generally not limited, and in some embodiments, may include metal, polyaramid, carbon fiber, nylon, polyester, glass, ceramic, and various composite materials, and may include composite mixtures of these materials. The size (e.g., diameter) of the cords 112 themselves is not limited, and can be selected based on the final desired use of the belt 100.

[0019] Figure 1 The belt 100 is further described as including a surface layer 113 formed on the surface features 111 of the belt 100. If applicable, the material and thickness of the surface layer 113 are generally not limited and can be selected, for example, based on the specific characteristics to be imparted to the belt using the surface layer 113. For example, the surface layer 113 can be provided to adjust the coefficient of friction of the belt 100, reduce the noise of the belt 100, etc.

[0020] Based on the specific use of the belt 100, the belt 100 may optionally include Figure 1For example, tape 100 may include a backing layer formed on a surface of body portion 110 opposite the surface on which surface features 111 are formed.

[0021] Back to Figure 1 The main body 110 of the belt 100 shown, one embodiment of the technology described here uses a mixable (or mixed) polyurethane as the main component of the main body material. Mixable polyurethane generally refers to a polyurethane produced with a stoichiometrically insufficient diisocyanate and in a solid but viscous or flexible form. That is, once mixed and optionally combined with other additives, the mixable polyurethane can be provided in the form of, for example, a solid but flexible sheet. As discussed in more detail below, these solid sheets of mixed polyurethane (which may be combined with additional components) can be further processed, such as applying pressure and heat molding, to produce various products with desired shapes (including, for example, surface features).

[0022] Any suitable remixable polyurethane can be used as the remixable polyurethane component of main body material, including polyether-based remixable polyurethane or polyester-based remixable polyurethane. The specific polyether used in polyether-based remixable polyurethane is not limited usually, and can include for example polytetramethylene ether glycol (PTMEG). The specific polyester used in polyester-based remixable polyurethane is not limited usually. Polyester and polyether-based remixable polyurethane may have different attributes, making them more suitable for specific purposes. For example, polyether-based remixable polyurethane has better hydrolysis resistance and water resistance, while polyester-based remixable polyurethane has heat resistance, oil resistance and compression set resistance.

[0023] For the composition of the main body material of the belt, the composition may contain more than 50 wt% of a mixable polyurethane based on the total elastomer content of the composition. In some embodiments, the mixable polyurethane content of the composition is greater than 60 wt%, greater than 70 wt%, greater than 80 wt%, or greater than 90 wt% of the total elastomer content in the material.

[0024] The remixable polyurethane component of the composition of the main body of the band can be composed of a single remixable polyurethane, or can be a composition of different remixable polyurethanes. Any combination of remixable polyurethanes can be used to provide the composition of the main body material with required remixable polyurethane content. In some embodiments of using multiple remixable polyurethanes, remixable polyurethanes can be all polyester-based remixable polyurethanes or all polyether-based remixable polyurethanes. In other embodiments, a mixture of polyether and polyester remixable polyurethanes can be used.

[0025] The composition of the main body material of the belt can also include one or more additional elastomers (i.e., elastomers different from the aforementioned remixable polyurethane component). When other elastomers are included in the composition, the other elastomers can be less than 50wt%, less than 25wt%, or about 5-10wt% of the total elastomer content of the composition. Exemplary but non-limiting additional elastomers that can be used with remixable polyurethanes include silicone rubber, EPDM, EPR, EOM, EBM, EBT, ethylene elastomers (e.g., ethylene acrylic elastomers), chloroprene rubber, epichlorohydrin, hydrogenated nitrile rubber, natural rubber, ethylene-vinyl acetate copolymers, ethylene-methacrylate copolymers and terpolymers, styrene-butadiene rubber, nitrile rubber, chlorinated polyethylene, chlorosulfonated polyethylene, alkylated chlorosulfonated polyethylene, octene polymer rubber (transpolyoctenamer), polyacrylic rubber, butadiene rubber and mixtures thereof. Adding additional elastomers can, for example, fine-tune certain mechanical features of the main body material, such as high temperature performance and viscosity.

[0026] In some embodiments, the composition of the main body material further comprises a reinforcing material. For example, reinforcing particles can be dispersed throughout the composition. In some embodiments, the composition of the main body material comprises about 25-250 phr, such as about 25-100 phr of reinforcing particles such as carbon black, calcium carbonate, talc, clay or hydrated silica or a mixture thereof.

[0027] In the composition, the reinforcing material can also be provided in the form of reinforcing fibers. For example, in some embodiments, the composition includes discontinuous fibers dispersed in the whole material. Reinforcing fibers can be conventional staple fibers or pulp fiber reinforcements. Examples of fibers with suitable tensile modulus and wear resistance have polyaramid fibers, such as those sold by EI du Pont de Nemours & Company with trademarks KEVLAR, those sold by Teijin of Japan with trademarks TECHNORA, and those sold by Enka of the Netherlands with trademarks TWARON. Non-polyaramid fibers can also be applied, no matter whether they are synthetic or natural. The length of the staple fibers can be less than 0.25mm to about 12mm, such as about 0.5-7mm or about 1-3mm. When reinforcing fibers are applied, the composition can include reinforcing fibers of about 0.5-20vol%, such as about 1-6vol%. In some embodiments, the reinforcing fibers are oriented perpendicular to the direction of travel of the band in the main body material.

[0028] The composition of the main body material can also include a curing agent. Any curing agent capable of curing the composition of the main body material can be applied. In some embodiments, the curing agent is selected from sulfur-based and / or peroxide-based curing systems. Although not restrictive, suitable peroxide-based curing systems include diisopropylbenzene peroxide, bis-(tert-butyl peroxy) diisopropylbenzene, tert-butyl perbenzoate, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di-tert-butyl peroxyhexane and α-α-bis (tert-butyl peroxy) diisopropylbenzene. The curing effective amount of peroxide curing agent can be about 2-15phr, for example, about 4-6phr. Isocyanate curing agents can also be applied. Mixtures of different types of curing systems (for example mixed sulfur peroxide-based curing systems) can also be used.

[0029] Any other suitable additives may be included in the composition of the main body material. Although not restrictive, exemplary additives that may be included include processing oils and filler oils, antioxidants, waxes, pigments, plasticizers, softeners, anti-hydrolysis agents, etc. In some embodiments, auxiliary agents are included in the composition of the main body material. Suitable auxiliary agents are co-cured with the main curing system (e.g., peroxide curing system) and may contribute to the cured state and modulus of the enhanced composition.

[0030] As previously described, the use of a millable polyurethane in forming the material for the body portion of the belt means that a solid but flexible sheet of body portion material can be provided when producing a power transmission belt. For example, a layer or sheet of body portion material can be prepared using a millable polyurethane and other additives, and these layers or sheets can be distributed to a belt production location so that a layer or sheet of body portion material incorporating the milled polyurethane can be used during the belt production process.

[0031] The specific techniques and methods used in forming the main body material comprising the remixable polyurethane are generally not limited, as long as the flexible solid sheet or layer of the main body material has been prepared. Suitable equipment includes but is not limited to a double roll mixer, a double roll mixer, an internal mixer, a calender, a kneader, etc. In some embodiments, a double roll mixer or a calender is used to produce a layer of the main body material. In such embodiments, the remixable polyurethane (which usually has a solid but viscous consistency in its original state) passes through a double roll mixer (or an internal mixer), and then various additives (such as reinforcing materials, additional elastomers, curing agents, etc.) to be added to the remixable polyurethane passing through the double roll mixer or the internal mixer may be added. Application of regular end cutting helps to ensure that the remixable polyurethane is fully and evenly mixed with other additives. After fully mixing, a flexible solid layer or sheet of the main body material is produced. Other suitable equipment that can be used to produce the main body material includes an internal mixer, which generally also includes adding materials in order to produce a large amount of main body materials. This large amount of material may need to form a sheet or layer of material by a mixer. Generally speaking, the layer or sheet of the material can be cooled to slightly harden the material. The sheet or material is in an uncured state and contains a curing agent added during sheet preparation so that a subsequent curing step (such as during the production of the tape described in more detail below) can be performed.

[0032] Once a solid sheet of material used in forming the main body of the band is prepared, the sheet of material can be provided to any place where standard (i.e., non-dedicated) molding equipment can be applied. For example, and as described in more detail below, when the material of the main body of the band can be obtained as a solid moldable sheet, thick sheet construction technology and equipment can be applied to form the band. Since the equipment used for this type of band production technology is relatively cheap, the equipment is easy to obtain and widely distributed. This means that the band can be produced in multiple locations without being limited to places where specialized equipment can be obtained. This generally increases production capacity and reduces the total cost of producing such bands. In addition, compared with liquid materials used in other band production processes, solid sheets of the main body material formed by using mixable polyurethane are easier to transport and handle, which also reduces costs and improves output.

[0033] refer to Figure 2, a method 200 for producing a power transmission belt using a flexible solid sheet of a kneadable polyurethane-based material includes a step 210 of constructing a thick sheet of a plurality of layers on a first mold portion, wherein at least one of the plurality of layers constitutes a kneadable polyurethane-based body portion material layer, a step 220 of encapsulating the plurality of layers with a second mold portion disposed on the first mold portion, and a step 230 of applying heat and / or pressure to the plurality of layers disposed in the mold to mold the plurality of layers together and in some cases to form a plurality of surface features on an upper surface or a lower surface of the plurality of layers. The molding process is generally designed to form any type of surface features in the body portion layer of the belt (comprising the kneadable polyurethane).

[0034] For step 210, a plurality of layers are placed in a portion of a mold using a slab construction technique, the plurality of layers being various materials of the tape placed sequentially in the mold. That is, the slab construction process typically requires sequentially providing each layer of the tape structure on a portion of a mold so that the mold can be encapsulated and exposed to pressure and / or heat to form the structure of the tape, and the materials of the tape are cured into a final form.

[0035] In some embodiments, the mold for implementing the thick sheet construction process is a cylindrical drum or mandrel, and the diameter of the drum is approximately equal to the diameter of the formed belt. The specific diameter is not limited and can be any diameter required for the belt product.

[0036] In some embodiments, the first layer placed on the drum mold is a backing material. Any backing material applicable to the belt structure can be applied. Similarly, the thickness of the backing material is not limited, and can be adjusted according to the required thickness of the backing layer of the resulting belt. In some embodiments, the backing material is a rubber material, but is typically a rubber material different from the elastomeric material used with the main body of the belt. In other embodiments, the backing material can include one or more of textiles, adhesive rubbers, etc.

[0037] After the backing material is placed on the drum mold, the thick sheet construction process usually requires one or more layers of the main body material to be wound onto the backing material on the cylindrical drum. As described above, the main body material layer is a sheet of a flexible solid mixable polyurethane-based material, which is prepared before the thick sheet construction process described in more detail above. For example, these material layers can be prepared using a calendering or mixing process at a compounding location separate from the location of the implementation method 200, so that a sheet of mixable polyurethane-based material can be provided for any location where the equipment of the implementation method 200 is located.

[0038] After a certain amount of recyclable polyurethane-based sheet layers are wound around the cylindrical mold, the rope layer can be wound around the cylindrical mold. In some embodiments, usually a single rope layer is wound around the entire length / width of the mold. Can be pressed by the demand of the finished product, adjustment parameters such as the spacing between the winding angle, winding tension and the adjacent winding of the rope. Then the additional layer of recyclable polyurethane-based material is wound around the cylindrical mold, thereby the rope is embedded between the recyclable polyurethane-based material layer.

[0039] A final optional surface layer may then be applied to the millable polyurethane base material to complete the thick sheet construction process of step 210. The surface layer may be any suitable surface layer material for belt applications, such as braided tubes and polyethylene films. The thickness of the surface layer is generally not limited and may be adjusted according to the specific use of the belt being formed.

[0040] After the thick sheet construction process of step 210 is completed, step 220 is implemented to use an overmold to encapsulate the composite belt structure between the inner (drum) mold portion and the overmold portion. The overmold portion can be generally cylindrical, mirroring the inner mold drum, so that the composite belt structure can be encapsulated and a belt with uniform thickness can be formed. In embodiments where the formed belt does not have teeth, ribs, etc. formed therein, the overmold can have a flat inner surface. Alternatively, the inner surface of the overmold can have a certain profile to produce any surface features (such as teeth, ribs, etc.) required for the belt product, including providing the surface features with the size, shape and spacing generally required. In general, the size of the profile in the overmold should mold the outer layer of the recyclable polyurethane-based material, thereby forming surface features in the recyclable polyurethane material portion of the belt.

[0041] In step 230, which may occur at least partially simultaneously with step 220, heat and / or pressure is applied to the material layers loaded into the mold, thereby molding the multiple layers together, curing the material in the mold, and forming a plurality of surface features in the outer layer of the kneadable polyurethane-based material. The specific heat and pressure applied in step 230 is generally not limited, so long as the surface features (if provided) are molded into the kneadable polyurethane-based material, the composite tape structure is molded together as a whole, and any necessary curing is performed to cure the material layers of the tape.

[0042] Once step 230 has been performed, the mold can be opened and the strip removed from the mold. Any necessary subsequent processing steps can be performed, such as slicing a larger strip into multiple thinner strips, grinding, polishing, etc. Based on the above method, the strip can also be reversed so that the surface features face radially inward.

[0043] Although the above method requires the use of an inner mold in which the backing layer is first placed and an outer mold having a profile for forming surface features in the tape, it should be understood that the molding method and mold applied can be reversed. For example, the inner mold can include a profile for forming surface features in the tape, in which case the first material placed in the mold is the (optional) surface layer rather than the backing layer. The slab construction process will then continue with the placement of the kneadable polyurethane-based material layer, the rope layer, the kneadable polyurethane-based material layer and the backing layer, followed by the mold being partially encapsulated with the outer mold that does not include a profile for forming surface features.

[0044] As previously mentioned, there is no limitation on the specific type of power transmission belt formed according to the various embodiments described herein. Exemplary belt types that can be formed using the techniques described herein include, but are not limited to, synchronous belts, V-belts, and micro-V-belts. Similarly, there is no limitation on the specific application of the power transmission belt formed using the techniques described herein.

[0045] As used herein, in some embodiments, the term mixable polyurethane can be considered synonymous with mixed polyurethane. For example, in embodiments where the main body material layer has been prepared and / or used to produce a power transmission belt, the main body material includes a mixable polyurethane that has been mixed in the process of forming a layer or sheet of the main body material, so it can be considered that the material includes the mixed polyurethane at this point. The key factor is that the polyurethane used in the embodiments described here is a type with a solid state but still having viscosity, and can thus be mixed or calendered to form a soft material sheet or layer. This is different from, for example, the formation of castable polyurethane, which cannot be mixed due to its liquid properties.

[0046] From the foregoing it will be appreciated that specific embodiments of the present invention have been described for purposes of illustration, but that various changes may be made without departing from the scope of the invention. Accordingly, the present invention is limited only by the appended claims.

[0047] Although the technology has been described in language specific to certain structures and materials, it should be understood that the invention defined in the appended claims is not limited to the specific structures and materials described. Instead, the specific aspects are described as forms for implementing the claimed invention. Because many embodiments of the present invention can be implemented without departing from the spirit and scope of the present invention, the present invention is present in the claims appended hereto.

[0048] Unless otherwise stated, all numbers or expressions (such as indicating dimensions, physical properties, etc.) used in this specification (except claims) should be understood as modified by "about" in all cases. At least and not to limit the application of the principle of equivalents in the claims, each numerical parameter modified by the term "about" quoted in the specification or claims should be understood at least based on its number of significant digits and applying rounding technology. In addition, all ranges disclosed herein should be understood to cover and support any and all sub-ranges or any and all single values ​​included therein. For example, the range 1-10 should be understood to cover and support any and all sub-ranges or single values ​​between and including the minimum value 1 and the maximum value 10. That is, all sub-ranges (such as 5.5-10, 2.34-3.56, etc.) starting with a minimum value 1 or a larger value and ending with a maximum value 10 or a smaller value or any value of 1-10 (such as 3, 5.8, 9.9994, etc.).

Claims

1. A power transmission belt comprising a main body portion, the composition of the main body portion comprising a millable polyurethane.

2. The power transmission belt according to claim 1, wherein the millable polyurethane is a polyester-based millable polyurethane.

3. The power transmission belt according to claim 1, wherein the millable polyurethane is a polyether-based millable polyurethane.

4. The power transmission belt of claim 1, wherein the total elastomer content of the composition of the main body portion is greater than 50 wt% of millable polyurethane.

5. The power transmission belt of claim 1, wherein the composition of the body portion further comprises at least one additional elastomer, the additional elastomer being different from the millable polyurethane.

6. The power transmission belt according to claim 1, wherein the composition of the main body portion is a peroxide-cured composition or a sulfur-cured composition.

7. The power transmission belt of claim 1, wherein the composition of the body portion further comprises a reinforcing filler, the reinforcing filler being dispersed throughout the body portion.

8. The power transmission belt of claim 7, wherein the reinforcing filler comprises reinforcing particles, chopped fibers, or a combination thereof.

9. The power transmission belt of claim 1, wherein a plurality of surface features are formed on a surface of the body portion.

10. The power transmission belt of claim 9, wherein the plurality of surface features are ribs oriented perpendicular to the rotational axis of the power transmission belt or teeth oriented parallel to the rotational axis of the power transmission belt.

11. The power transmission belt of claim 1, wherein a plurality of tension cords are embedded in the body portion, the plurality of tension cords being oriented perpendicular to a rotation axis of the power transmission belt.

12. The power transmission belt according to claim 1, wherein the power transmission belt is a synchronous belt, a V-belt or a micro V-belt.

13. A method for producing a power transmission belt, comprising: constructing a plurality of layers of thick sheets on the first portion of the mold, wherein at least one of the plurality of layers constitutes a layer of a main body material, the main body material comprising a kneadable polyurethane; encapsulating the plurality of layers with a second mold portion disposed on or over the first mold portion; and Heat and / or pressure are applied to the plurality of layers disposed in the mold to mold the plurality of layers together and optionally to form a plurality of surface features on an upper surface or a lower surface of the plurality of layers.

14. The method of claim 13, wherein the millable polyurethane is a polyester-based millable polyurethane.

15. The method of claim 13, wherein the millable polyurethane is a polyether-based millable polyurethane.

16. The method of claim 13, wherein the total elastomer content of the body portion material is greater than 50 wt% of millable polyurethane.

17. A kneadable polyurethane composition suitable for preparing a sheet of a power transmission main body material, the composition comprising: Polyether or polyester based can be mixed with polyurethane; optionally at least one additional elastomer different from the polyether or polyester based millable polyurethane; Curing agent; and A reinforcing filler dispersed in the composition.

18. The millable polyurethane composition of claim 17, wherein the total elastomer content of the composition is at least 50 wt% millable polyurethane.

19. The millable polyurethane composition of claim 17, wherein the composition comprises at least one additional elastomer, and the at least one additional elastomer is selected from the group consisting of silicone rubber, EPDM, EPR, EOM, EBM, EBT, ethylene elastomers, chloroprene rubber, epichlorohydrin, hydrogenated nitrile rubber, natural rubber, ethylene-vinyl acetate copolymers, ethylene-methacrylate copolymers and terpolymers, styrene-butadiene rubber, nitrile rubber, chlorinated polyethylene, chlorosulfonated polyethylene, alkylated chlorosulfonated polyethylene, octene polymer rubber, polyacrylic rubber, butadiene rubber, and mixtures thereof.

20. The millable polyurethane composition of claim 17, wherein the curing agent is a sulfur curing agent, a peroxide curing agent, or a mixed peroxide-sulfur curing agent.

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