CN111819011A - Contact cleaning surface assembly and method of making the same - Google Patents

Abstract

A contact cleaning surface assembly and a method of manufacturing the same, the contact cleaning surface assembly comprising an elastomer layer having a bulk conductivity (e.g., electrical conductivity), the elastomer layer (112) having a conductive surface (114) for contacting a component to be cleaned and another conductive surface (113) for electrical contact with a conductive path (110) for extracting charge from the conductive layer (112).

Description

Contact cleaning surface assembly and method of making the same

technical field

The present invention relates to a contact cleaning surface assembly for use in a contact cleaning process, in particular, but not exclusively, to a contact cleaning surface assembly including an elastomeric layer having bulk conductivity. The present invention also relates to a method of making a contact cleaning surface assembly.

Background technique

Use contact cleaning to clean substrate surfaces. Once the substrate surface is cleaned, the substrate surface can be used in a variety of complex processes, such as for the manufacture of electronic devices, optoelectronic devices and flat panel displays. Typically, a rubber or elastomer cleaning roller is used to remove contaminating particles from the surface of the substrate, and then an adhesive roller can be used to remove the contaminating particles from the cleaning roller.

In operation, the contact cleaning roller contacts at least the upper surface of the substrate to remove debris through adhesion removal mechanisms (eg, van der Waals and adhesion forces) in which the inherent properties of the materials used to form the contact cleaning roller attract Debris and cause debris to adhere to the surface of the contact cleaning roller. It is believed that the contact cleaning roller pulls particles away from the substrate surface in this manner due to the mutually attractive van der Waals forces between the contamination particles and the roller. Therefore, existing contact cleaning rollers can ensure the effectiveness of removing contaminating particles by maximizing contact with the substrate surface.

In addition to the weak van der Waals electrostatic forces inherent in the material of the contact cleaning roller, other electrostatic charges may be generated. Contact cleaning processes rely on contact between different surfaces and can potentially be a source of electrical charges from triboelectric effects and static charge build-up. Therefore, in an electronics assembly factory, any equipment used in close proximity to a substrate (eg, within 100mm) must be non-insulating and must have a sufficiently low sheet resistance to prevent damage to the substrate from electrostatic charges.

When the contact cleaning roller has sufficient surface adhesion to clean the substrate (ie, the part to be cleaned), electrostatic charges can be generated during the contact cleaning process.

Surface resistance _Rs , defined as the ratio of voltage to current along the surface of a material, is a material property measured in ohms (Ω) and is defined as:

where U is the DC voltage and the surface current is _Is .

A well-known method for measuring surface resistance is provided in the American National Standards Institute (ANSI) ESD STM 11.11-2015 standard. According to this method, any device used by an electronic assembly factory within 100 mm of the substrate must have a surface resistance of less than 1×10 ⁹ Ω.

Bulk conductivity is usually obtained by measuring bulk resistance. A well-known method for measuring volume resistance is provided in the American National Standards Institute (ANSI) ESD STM11.12-2015 standard.

Typical rubber or elastomer cleaning rollers generally do not have a sheet resistance lower than 1 x ¹⁰⁹ Ω, in other words, they are insulating and non-conductive. It is desirable to provide a cleaning roller that allows static charge to dissipate away from the substrate to be cleaned.

It is not uncommon to use one or more additives to alter the properties of materials, such as those used in contact cleaning rollers, during the manufacturing process. However, additives will necessarily impart different properties to the original material, and changes to the original material run the risk of inhibiting its primary function (ie, contact cleaning). This risk is especially high when attempting to alter the surface properties of a contact cleaning roll if the surface is critical to the cleaning efficiency of the roll. Anything that reduces the amount of elastomer on the roll surface will likely mean that the elastomer will not be able to make adequate contact with the substrate to be cleaned, resulting in a reduced ability to contact and attract dirt and debris. Additionally, as discussed above, modifying additives may interfere with the usual process of attracting debris to the cleaning roll surface. In both cases, the cleaning efficiency of the rollers will be inhibited or reduced.

Common conductive additives, such as fibers and particles, may not be uniformly dispersed throughout the elastomeric matrix. As a result, the roller will have a non-uniform surface resistance, incorporating portions that conduct charge away from the clean surface and portions that allow charge to build up and damage the substrate.

It is a further consideration that the addition of additives to the elastomer should not affect the integrity of the elastomer or the roll. Loss of integrity or reduced wear resistance can cause the roll to wear too quickly or the surface to become damaged or pitted, further reducing its effectiveness. All of these factors can increase the operating costs of a contact cleaning process.

Furthermore, an additive material that is not sufficiently similar to the elastomer (eg, low bonding surface area) will mean that the surrounding elastomer cannot effectively bond or adhere to the additive. If the material is not firmly embedded in the elastomer, the material will be dislodged and off the surface of the roll as the roll operates, contaminating the substrate being cleaned and/or being picked up by the tacky roll, shortening its life and increasing operating costs . Additionally, if material is removed from the roll, it can result in damage to the roll surface, again reducing cleaning efficiency and increasing costs.

It is important not to use excess additives to achieve an appropriate reduction in surface resistance, as this material would not be cost effective and would likely make the contact cleaning roll cost prohibitive. Therefore, it is important to maximize the electrical connectivity provided by the additive while minimizing the amount of additive used.

Another related consequence of using large amounts of additives is that the amount of this material on the roll surface will increase and the amount of elastomer will decrease. The problem of elastomer reduction at the roll surface has been described above.

As the cleaning roller wears, it is important that its surface resistance is not affected, otherwise the risk of static build-up will increase during the life of the cleaning roller. If this happens, the rolls may need to be replaced early and operating costs will increase. Therefore, it is important that anything that improves the surface resistance of the roll must continue to do so throughout the life of the roll without loss of effectiveness.

As mentioned above, some cleaning applications are conditioned for the surface resistance of the cleaning surface to be less than 1 x ¹⁰⁹ Ω. Not only does this require the contact cleaning roller to have a surface resistance of less than 1 x 10 ⁹ Ω, but necessarily the roller must be able to allow electrostatic charge to be conducted from the cleaning surface to the ground. The roller must also do so when it is in continuous operation, ie the roller must enable electrical charge to be conducted at all times while it is rotating. Therefore, it may not be sufficient to provide a roller with low resistance in localized areas, but it must be able to conduct charge from the surface of the substrate to a suitable ground (ie, to ground) at all times during its operation.

It is an object of the present invention to alleviate or alleviate at least one or more of the above-mentioned problems.

It is an object of the present invention to alleviate or mitigate the problem of static charge build-up created by contact cleaning surface assemblies.

Another object is to alleviate or reduce the problem of static charge without reducing or inhibiting the cleaning effectiveness of the contact cleaning roller, or reducing the working life of the contact cleaning surface assembly or tacky roller.

Yet another object of the present invention is to reduce the surface resistance of a contact cleaning surface assembly to less than 1 x ¹⁰⁹ Ω, and further, while doing so, provide a path to allow conduction of electrostatic charge to ground.

Another object of the present invention is to reduce sheet resistance while minimizing the amount of non-insulating additives and maximizing their electrical connectivity.

Another object of the present invention is to improve connectivity while mitigating any reduction or improving the integrity of the contact cleaning surface assembly.

Another object of the present invention is to alleviate or reduce static charge when using a contact cleaning surface assembly for use in a suitable contact cleaning device.

In addition, it is yet another object of the present invention to provide a method of making a contact cleaning surface assembly capable of alleviating or mitigating static charges.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided a contact cleaning surface assembly comprising an elastomeric layer having a bulk electrical conductivity (eg, electrical conductivity), the elastomeric layer having a A conductive surface that the cleaned component contacts, and another conductive surface that is in electrical contact with a conductive path for extracting charge from the conductive layer.

In certain embodiments, the elastomeric layer is in electrical contact with the conductive paths.

In certain embodiments, the elastomeric layer is in intimate contact with the conductive paths.

In certain embodiments, the conductive path provides charge extraction (ie, electrical ground) from the elastomeric layer to ground.

In certain embodiments, the conductive path includes a metallic charge extraction element in contact with the conductive surface of the elastomeric layer.

In certain embodiments, the conductive paths are conductive supports of the elastomeric layer.

In certain embodiments, the elastomeric layer is in intimate contact with the support.

In some embodiments, the charge extraction path is from the conductive layer to the conductive path.

In certain embodiments, the elastomeric layer is attached to the conductive support.

In certain embodiments, the elastomeric layer is in intimate contact with the conductive support. More specifically, the elastomeric layer is in intimate contact with the support over the entire other conductive surface of the elastomeric layer. In this way, charge extraction from the elastomeric layer to the support occurs over the entire other conductive surface of the elastomeric layer.

In certain embodiments, the conductive support is formed of a metallic conductor material. More specifically, the metal conductor support is stainless steel.

In certain embodiments, the conductive support is formed of a non-metallic conductor material. More specifically, the non-metallic conductor supports are carbon fibers.

In some embodiments, the support is a shaft.

In certain embodiments, the charge extraction path is from the conductive layer to the conductive support. More specifically, the charge extraction path is from a conductive surface of the elastomeric material, through the elastomeric material to another conductive surface of the elastomeric material, to the conductive support.

In certain embodiments, the assembly is a roller.

In certain embodiments, the assembly includes a planar (or substantially planar) sheet.

In certain embodiments, the elastomeric layer includes conductive elements. More specifically, the elastomeric layer contains a modifier that contains the conductive elements. In this manner, the modifier reduces the bulk and surface resistance of the elastomeric layer and provides bulk conductivity to the elastomeric layer.

In certain embodiments, the conductive elements form a network. More specifically, the network of conductive elements is conductive. The conductive elements in the elastomeric layer are in close proximity or contact with each other so that the network of conductive elements provides a charge path from the outer conductive surface of the elastomeric layer, through the elastomeric layer to the other conductive surface of the elastomeric layer, to the conductive supporting item. In this way, electrical charge can be extracted from the substrate (ie, the part to be cleaned), passing through the elastomeric layer to the conductive support and then to the ground.

In certain embodiments, the elastomeric layer includes an interconnected network of conductive elements.

In certain embodiments, the conductive elements are elongated. In this way, the surface area of the conductive element in contact with the elastomer of the elastomeric layer is increased and the retention of the element in the elastomeric layer is enhanced.

In certain embodiments, the elongated conductive elements are hollow.

In certain embodiments, the conductive element is carbon.

In certain embodiments, the conductive elements are nanotubes.

In certain embodiments, the conductive elements are carbon nanotubes.

In certain embodiments, the nanotubes are single-walled carbon nanotubes. In this way, a balance is maintained between the cleaning properties of the elastomeric layer and its volume conductivity. The high surface area of nanotubes provides improved incorporation of carbon into elastomers compared to granular carbon or carbon fibers.

More specifically, carbon nanotubes are a single carbon atom wall thickness.

In certain embodiments, the or each conductive surface has a sheet resistance of less than 1×10 ⁹ Ω. More specifically, the surface resistance of both the conductive surface of the elastomer layer and the other conductive surface are less than 1×10 ⁹ Ω. Still more specifically, the sheet resistances of both the conductive surface and the other conductive surface of the elastomeric layer are substantially equal.

In certain embodiments, the or each conductive surface has a sheet resistance in the range of about 1×10 ⁶ Ω to about 1×10 ⁹ Ω. More specifically, the surface resistance of both the conductive surface and the other conductive surface of the elastomeric layer is in the range of about 1×10 ⁶ Ω to about 1×10 ⁹ Ω. Still more specifically, the sheet resistances of both the conductive surface and the other conductive surface of the elastomeric layer are substantially equal.

In certain embodiments, the elongated conductive elements are uniformly dispersed throughout the elastomeric material.

In certain embodiments, the conductive elements are dispersed so that they are embedded and retained in the elastomeric material.

In certain embodiments, the conductive elements are randomly oriented in the elastomeric material.

In certain embodiments, the conductive elements have a length in the range of about 5 μm to about 30 μm.

In certain embodiments, the conductive elements have diameters in the range of about 1 nm to about 200 nm.

In certain embodiments, the concentration of the conductive elements in the elastomer is at least about 0.015% by weight of the elastomer.

In certain embodiments, the elastomer includes one of silicone rubber or polyurethane.

In certain embodiments, the elastomer comprises silicone. In this way, when the carbon nanotubes are dispersed in the silicone material, a conductive silicone layer can be formed. The nanotubes are retained within the silicone polymer matrix by covalent bonding. Due to the fluidity of the silicone matrix, other additives such as particulate materials tend to migrate out of the silicone matrix. Thus, carbon nanotubes provide retention modifiers that remain within the silicone matrix.

In certain embodiments, the elastomer is a two-component room temperature cure silicone rubber.

According to another aspect of the present invention, there is provided a contact cleaning roller comprising:

core area,

and a surface region cladding the core region, wherein the surface region includes an elastomer and a plurality of elongated elements dispersed within the elastomeric material, wherein the elongated elements are formed of a non-electrically insulating material.

According to yet another aspect of the present invention there is provided the use of a contact cleaning surface assembly according to the present invention in a contact cleaning process.

According to another aspect of the present invention, there is provided a contact cleaning device comprising a contact cleaning surface assembly according to the present invention.

According to another aspect of the present invention, there is provided a method of manufacturing a contact cleaning roller, the method comprising:

provide elastomers in fluid form,

Disperse elongated elements formed from non-electrically insulating materials into an elastomer,

provide the core area of the contact cleaning roller, and

The core region is covered with elastomer.

In certain embodiments, the method then includes curing the elastomer.

According to yet another aspect of the present invention, there is provided a method of making a contact cleaning surface assembly, the method comprising:

Prepolymers to provide elastomers,

adding a polymer modifier formed from a non-electrically insulating material to the prepolymer,

cause the polymerization of the prepolymer,

The polymer is cured to form an elastomeric cleaning surface with bulk conductivity.

In certain embodiments, after curing, the conductive elements are dispersed throughout the elastomer.

In certain embodiments, after curing, the conductive elements form a network.

In certain embodiments, the conductive elements are oriented in random orientations.

Description of drawings

The invention will now be described by way of example only and with reference to the accompanying drawings, wherein:

1 is a schematic side view of a contact cleaning apparatus using a roller having a contact cleaning surface assembly in accordance with an embodiment of the present invention;

2 is a schematic cross-sectional view of a contact cleaning surface assembly in accordance with an embodiment of the present invention;

Figure 3a is another schematic cross-sectional view of a contact cleaning surface assembly according to a first embodiment of the present invention;

Figure 3b is a schematic enlarged cross-sectional view of a portion of the contact cleaning surface assembly of Figure 3a; and

4 is a schematic diagram of an elongated single-walled carbon nanotube according to an embodiment of the present invention.

Detailed ways

1 is a schematic side view of a contact cleaning device using a contact cleaning surface assembly as a roller according to an embodiment of the present invention. The contact cleaning device 1 includes a contact cleaning roller 2 and an adhesive roller 3 mounted above a conveyor 4, which carries a plurality of substrates 5 to be cleaned. The contact cleaning roller 2 is elongated and generally cylindrical, and is mounted on a support (not shown) having an axis perpendicular to the viewing plane around which the contact cleaning roller 2 is free rotate. The specific structure of the contact cleaning roller 2 will be described in more detail below. The adhesive roller 3 is generally cylindrical and comprises a body having a surface on which the adhesive is present and also mounted on a support (not shown) having a surface perpendicular to the viewing plane and with The axis of the contact cleaning roller 2 is parallel to the axis about which the adhesive roller 3 is free to rotate. The contact cleaning roller 2 and the tacky roller 3 are mounted in contact with each other so that a clockwise rotational movement of the contact cleaning roller 2 results in a counter-clockwise rotational movement of the tacky roller 3 and vice versa. From the description of use below, it will be clear that the contact cleaning roller 2 and the tacky roller 3 need to be in contact. The contact cleaning roller 2 is also mounted so that it can come into contact with the surface of the substrate 5 to be cleaned when the substrate 5 to be cleaned is conveyed on a conveyor located below the axis of the conveyor 4 .

The substrate 5 to be cleaned is processed as follows. The substrate 5 is located on the upper surface 6 of the conveyor 4 which moves from right to left as indicated by arrow A in FIG. 1 . The substrate 5 to be cleaned passes under the contact cleaning roller 2, which rotates in a clockwise direction as indicated by arrow B. Before coming into contact with the contact cleaning roller 2, the upper surface of the substrate 5 is covered with debris 7 that needs to be removed, such as dust. The contact cleaning roller 2 is in contact with the upper surface of the substrate 5, removing debris 7 by an electrostatic removal mechanism, wherein the inherent polarity of the material used to form the contact cleaning roller 2 attracts the debris 7 and makes it adhere to the contact cleaning surface of roll 2. The relative attractive force between the surface of the contact cleaning roller 2 and the debris 7 is greater than the relative attractive force between the debris 7 and the surface of the substrate 5, so the debris 7 is removed. The now cleaned substrate 5 continues along the conveyor 4 to a removal station (not shown) and the lower surface 8 of the conveyor returns, forming a loop in the left-right direction in FIG. 1 as indicated by arrow D. In order to clean the contact cleaning roller 2 , an adhesive roller that rotates counterclockwise as indicated by arrow C is brought into contact with the surface of the contact cleaning roller 2 . At this time, the adhesive force between the chips 7 and the adhesive present on the surface of the adhesive roller 3 is greater than the adhesion force holding the chips 7 to the surface of the contact cleaning roller 2, and the chips are removed. The contact cleaning roller 3 is then rotated to present a clean surface to the next substrate 5 to be cleaned.

2 is a schematic cross-sectional view of a touch cleaning surface assembly according to a first embodiment of the present invention. The contact cleaning surface assembly in the form of a roller is used as a contact cleaning roller in the contact cleaning system 1 as described above. The roller 102 includes a conductive path, which is a conductive support 110 encased in a layer 112 of conductive elastomer. The roller 102 is elongate and generally cylindrical, and is mounted via a mounting mechanism to a bracket (not shown) for use in the contact cleaning device 1 . The conductive shaft 110 is coaxial with the conductive elastomer layer 112 . The shaft 110 may be used for mounting the roller 102 and, in use, for rotational movement of the roller 102. Suitably, such a shaft 110 is formed from an electrically conductive material, such as a metallic or non-metallic or composite conductive material such as stainless steel or carbon fiber composite material. The conductive shaft 110 is encased in an elastomeric material 112 (eg, rubber or other natural or synthetic elastomeric material). The elastomeric material is substantially homogeneous.

The conductive elastomer layer 112 has a conductive outer surface 114 having a surface resistance of less than 1×10 ⁹ Ω. The conductive elastomer layer 112 has a conductive inner surface 113 having a surface resistance of less than 1×10 ⁹ Ω and is in contact with the conductive shaft 110 . In this manner, a conductive path is formed from the outer surface 114 to the inner surface 113 to the shaft 110 . During cleaning of components (not shown) using the contact cleaning roller 102 , the electrostatic charge generated at the surface 114 is conducted through the layer 112 to the conductive paths provided by the conductive shaft 110 .

Figure 3a is a schematic cross-sectional view of a contact cleaning surface assembly in the form of a roller 102 in accordance with an embodiment of the present invention. FIG. 3b is a schematic enlarged cross-sectional view of a portion of the same roll 102 . Roller 102 includes elastomeric layer 112 having outer conductive surface 114 and inner conductive surface 113 . A conductive elastomer layer 112 coats and adheres to the conductive stainless steel shaft 110 . The outer surface 114 can be used to remove debris from the substrate surface in the manner described above.

In the described arrangement, the elastomeric layer is a two-component room temperature cured silicone rubber.

The elastomeric layer 112 includes a plurality of elongated single-wall carbon nanotubes 116 dispersed and embedded within the elastomeric material. Elongated single-walled carbon nanotubes 116 are dispersed within the elastomer of layer 112 and form an interconnected network of carbon nanotubes 118 . The dispersion of the nanotubes 116 within the elastomer causes the members to be dispersed in random orientations throughout substantially the entire thickness of the surface region 112, from the inner conductive surface 113 to the outer conductive surface 114 in contact with the conductive shaft 110. The nanotubes also extend substantially over the axial width of the roll 102 . Furthermore, when the nanotubes 116 comprise a non-electrically insulating material, then the entire surface area 112 has reduced electrical resistance or increased electrical conductivity compared to the elastomer alone. In this manner, the elastomeric layer 112 has bulk conductivity provided by the interconnected network of carbon nanotubes 118 .

The bulk conductivity of the elastomeric material in layer 112 provides a charge path to ground for charges generated during cleaning operations. Thus, not only does the roller exhibit reduced electrical resistance when it is new, but even as the outer surface 114 wears, this effect will continue throughout its useful life.

The dispersion of the elongated carbon elements 116 and the formation of the network 118 results in a reduced sheet resistance (measured according to the ANSI ESD STM 11.11-2015 standard) at the conductive surfaces 113 and 114 of less than 1×10 ⁹ Ω. In addition, because the entire elastomeric layer 114 has a reduced electrical resistance, the rollers 102 can provide a path that allows electrostatic charge to conduct away from the surface of the substrate to ground.

FIG. 4 depicts an elongated single-walled carbon nanotube 116 according to an embodiment of the present invention. Nanotube 116 is one of a plurality of similar elongated single-wall carbon nanotubes dispersed within elastomeric layer 112 .

The length of each single-walled carbon nanotube 116 may vary in the range of 5-30 μm, and may have a diameter in the range of 1-200 nm. In the embodiment of Figures 3a and 3b, the single-walled carbon nanotubes comprise 0.02% by weight of the elastomer comprising the elastomeric layer 112.

The elongated single-walled carbon nanotubes 116 are dispersed such that they form a conductive network extending substantially throughout the elastomeric layer 112 (118, Figure 3b). Thus, if any static charge begins to accumulate on the outer surface 114, the static charge will dissipate from the substrate surface to the shaft 110 immediately before damaging the substrate.

The elongated single-walled carbon nanotubes 116 ensure efficient interconnectivity in the network 118 . In other words, when nanotubes 116 are added in very low amounts, nanotubes 116 substantially reduce the electrical insulating properties of the elastomer due to their low weight per unit length and high surface area per unit length. Therefore, only a small amount is required to ensure an effective reduction of the sheet resistance of the roll 102 and to provide the desired bulk conductivity to the elastomeric layer compared to other conductive additives.

The hollow shape of the elongated single-wall carbon nanotubes 116 provides a high surface area for a given weight of element, which ensures sufficient bonding with the surrounding elastomer so that each elongate member 116 is firmly embedded within the elastomeric layer 112 . Thus, the elongated elements 116 cannot separate or loosen from the roller 102 when the elastomeric layer conductive surface 114 wears in use.

Furthermore, the embedding of the elongated single-wall carbon nanotubes 116 ensures that the integrity of the elastomer does not deteriorate, and may even improve or enhance the surface area 112 .

Nanotubes 116 form a charge path from outer conductive surface 114 through interconnect network 118 to inner conductive surface 113 to conductive axis 110 . The charge may be grounded from the shaft 110 by any suitable grounding means (not shown).

Various modifications and embodiments of the described embodiments are contemplated. For example, the grounding device may be electrically connected to the contact cleaning roller by any suitable means.

In another embodiment of the present invention, the elastomer of the surface region 112 comprises polyurethane or silicone rubber. In further embodiments, the elastomer may also be a thermally cured silicone, or other material suitable for contact cleaning rollers, as known to those skilled in the art.

In embodiments of the present invention, the cleaning surface assembly may clean both sides of the substrate (ie, the part to be cleaned). Both sides can be cleaned simultaneously or separately.

Throughout the specification and claims of this specification, the words "including" and "comprising" and their conjugations mean "including but not limited to" and are not intended (and do not) exclude other parts, additives, components, whole piece or step. Throughout the specification and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, unless the context requires otherwise, the specification should be read with both the plural and the singular being considered.

Features, integers, properties, compounds, chemical moieties or groups described in connection with a particular aspect, embodiment or example of the invention should be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible with it. All features disclosed in this specification (including any accompanying claims, abstract and drawings) and/or all steps of any method or process disclosed herein may be combined in any combination except where at least some of such features and and/or in mutually exclusive combinations of steps. The invention is not limited to the details of any preceding embodiment. The invention extends to any novel one or any novel combination of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to steps in any method or process disclosed as such. Any novel one step or any novel combination.

Claims (40)

1. A contact cleaning surface assembly includes an elastomeric layer having a bulk conductivity (e.g., electrical conductivity) having an electrically conductive surface for contacting a component to be cleaned and another electrically conductive surface in electrical contact with an electrically conductive path for extracting electrical charge from the electrically conductive layer.

2. The contact cleaning surface assembly of claim 1, wherein the elastomeric layer is in electrical contact with the conductive path.

3. The contact cleaning surface assembly of claim 2, wherein the elastomer layer is in intimate contact with the conductive path.

4. The contact cleaning assembly of claim 1 or 2, wherein the conductive path is a conductive support for the elastomeric layer.

5. The contact cleaning surface assembly of claim 3, wherein the elastomeric layer is in intimate contact with the support.

6. The contact cleaning surface assembly of any of claims 1 to 5, wherein a charge extraction path is from the conductive layer to the conductive path.

7. The contact cleaning surface assembly of any of the preceding claims, wherein the assembly is a roller.

8. The contact cleaning surface assembly of any of claims 1 to 6, wherein the assembly comprises a planar (or substantially planar) sheet.

9. The contact cleaning surface assembly according to any of the preceding claims, wherein the elastomeric layer comprises conductive elements.

10. The contact cleaning surface assembly of claim 9, wherein the conductive elements form a network.

11. The contact cleaning surface assembly of claim 9 or 10, wherein the network is electrically conductive (e.g., adjacent to or in contact with each other).

12. The contact cleaning surface assembly according to any of the preceding claims, wherein the elastomeric layer comprises an interconnected network of conductive elements.

13. The contact cleaning surface assembly of claim 12, wherein the conductive elements are elongated.

14. The contact cleaning surface assembly of claim 12 or 13, wherein the elongated conductive elements are hollow.

15. The contact cleaning surface assembly according to any of claims 12 to 14, wherein the conductive element is carbon.

16. The contact cleaning surface assembly of any of claims 12-15, wherein the conductive elements are nanotubes.

17. The contact cleaning surface assembly according to any of claims 12 to 16, wherein the conductive elements are carbon nanotubes.

18. The contact cleaning surface assembly of claim 16 or 17, wherein the nanotubes are single-walled carbon nanotubes.

19. The contact cleaning surface assembly of claim 18, wherein the carbon nanotubes are of a single carbon atom wall thickness.

20. The contact cleaning surface assembly of any of the preceding claims, wherein the or each conductive surface has a surface resistance of less than 1 x 10⁹Ω。

21. The contact cleaning surface assembly of any of the preceding claims, wherein the surface resistance of the or each conductive surface is at about 1 x 10⁶Omega to about 1X 10⁹In the range of omega.

22. The contact cleaning surface assembly according to any one of claims 4 to 21, wherein the support is a shaft.

23. The contact cleaning surface assembly according to any of the preceding claims, wherein the elongated conductive elements are uniformly dispersed throughout the elastomeric material.

24. The contact cleaning surface assembly according to any of claims 9 to 23, wherein the conductive elements are dispersed such that they are embedded and retained in the elastomeric material.

25. The contact scrub roller of any of claims 9 to 24, wherein the conductive elements are randomly oriented in the elastomeric material.

26. The contact cleaning surface assembly of any of claims 9 to 25, wherein the conductive elements have a length in the range of about 5 μ ι η to about 30 μ ι η.

27. The contact cleaning surface assembly of any of claims 9 to 26, wherein the conductive elements have a diameter in the range of about 1nm to about 200 nm.

28. The contact cleaning surface assembly of any of claims 9-28, wherein the concentration of the conductive element in the elastomer is at least about 0.015% by weight of the elastomer.

29. The contact cleaning surface assembly according to any of the preceding claims, wherein the elastomer comprises one of silicone rubber or polyurethane.

30. The contact cleaning surface assembly according to any of the preceding claims, wherein the elastomer comprises one of a thermally cured silicone or polyurethane.

31. The contact cleaning surface assembly of claim 30, wherein the elastomer is a two-part room temperature curing silicone rubber.

32. A contact cleaning surface roller comprising:

in the region of the core portion,

and a surface region encasing the core region, wherein the surface region comprises an elastomer and a plurality of elongate elements dispersed within the elastomer material, wherein the elongate elements are formed of a non-electrically insulating material.

33. Use of the contact cleaning surface assembly of any one of claims 1 to 31 in a contact cleaning process.

34. A contact cleaning device comprising the contact cleaning surface assembly of any one of claims 1 to 31.

35. A method of making a contact scrub roller, the method comprising:

the elastomer is provided in the form of a fluid,

dispersing elongated elements formed of electrically non-insulating material into said elastomer,

providing a core region of a contact scrub roller, an

Coating the core region with the elastomer.

36. The method of claim 35, subsequently comprising curing the elastomer.

37. A method of making a contact cleaning surface assembly, the method comprising:

there is provided a prepolymer of an elastomer which,

adding a polymer modifier formed of a non-electrically insulating material to the prepolymer,

causing the polymerization of the pre-polymer to take place,

the polymer is cured to form an elastomeric cleaning surface having bulk conductivity.

38. A method as claimed in any of claims 35 to 37, wherein after curing, the conductive elements are dispersed throughout the elastomer.

39. A method according to any one of claims 35 to 38, wherein after curing, the conductive elements form a network.

40. A method according to any one of claims 35 to 39, wherein the conductive elements are oriented in random orientations.

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