WO2005021833A2

WO2005021833A2 - Apparatus for the coating and/or conditioning of substrates

Info

Publication number: WO2005021833A2
Application number: PCT/GB2004/003657
Authority: WO
Inventors: Luke Ward; Jas Pal Badyal
Original assignee: Surface Innovations Limited
Priority date: 2003-08-28
Filing date: 2004-08-26
Publication date: 2005-03-10
Also published as: GB2419358B; GB2419358A; GB0601542D0; WO2005021833A3

Abstract

The invention relates to apparatus and a method for the deposition and/or conditioning of coatings which are applied to substrates or a substrate which pass through the apparatus. The apparatus includes at least one coating material deposition means and a means for movement of the substrate to expose at least a portion of said substrate to the coating material in the coating chamber. Plasma generating means are provided and the said portion of substrate and coating material are exposed to the plasma. The coating material deposition means are provided to apply the said material in an atomised form into the coating chamber in which the plasma is generated and the deposited material is exposed to the plasma prior to and/or once applied to the said portion of the substrate. This allows the improved application of coating materials onto the substrates.

Description

Apparatus for the Coating and /or Conditioning of Substrates

The invention to which this application relates is apparatus for the deposition and/or conditioning of coatings which are applied to substrates or a substrate which pass through the apparatus.

There are many known types of apparatus for the application of coatings onto substrates in which the material which forms the coating undergoes conditioning via plasma either as the material approaches the substrates and/or once the material has been applied to the substrates.

This application is particularly directed to the deposition of material at a relatively high deposition rate in a plasma treatment chamber. The plasma can typically be introduced in a pulsed or non pulsed manner but do so in a manner which allows the required deposition rates to be achieved, allow the deposition of a uniform coating to be achieved and to do while the substrate is maintained at uniform tension, positioning and the like with respect to the depositing apparatus thereby overcoming the conventional problems of lack of uniformity and reliability..

The aim of the present invention is to provide apparatus in a form which enables the application of highly functionalised coatings via the rapid deposition of material and which coatings retain full monomer functionality, with the material to be deposited initially provided in an involatile liquid and/or solid/liquid slurry condition. A further aim is to provide a variation and, if required, optimisation of the coating material in the atomised form prior to the same being applied to the substrates and, typically prior to the same entering the deposition chamber. In a first aspect of the invention there is provided apparatus for the deposition of a coating onto at least one substrate, said apparatus including at least one coating material deposition means; substrate movement means for moving the substrate to expose at least a portion of said substrate to the coating material and plasma generating means for generating a plasma to which the said portion of substrate and the coating material are exposed and wherein the deposition means is provided to apply the said material in an atomised form into a coating chamber in which the plasma is generated such that the deposited material is exposed to the plasma prior to and/or once applied to the said portion of the substrate.

In one embodiment the plasma is generated in a pulsed manner.

In one embodiment, the substrate is a sheet material and is fed through the apparatus from a feed roll to a rewind or collection roll to allow, at any given time, a portion of the sheet material to be exposed to the coating procedure. In one embodiment the sheet material is fed through the apparatus in a continuous manner or, alternatively, can be fed in a stepwise manner. In whichever embodiment the apparatus includes means for controlling any or any combination of the tension, speed, and alignment of the web of sheet material and, particularly when the sheet material includes elasticity, such as for example when the sheet material has any of textile, knitted, non woven or woven characteristics, and yet further where the spacing between fibrils in the sheet material can govern the penetration of the plasma into the sheet material.

In one embodiment the apparatus includes a plurality of coating stations, each coating station including deposition means to allow a coating material to be selectively introduced into a deposition volume and a plasma deposition means for generating a plasma, typically pulsed, at each deposition volume, such that each coating station, independently of the others, applies a defined coating or conditioning effect to the portion of the sheet material substrate which is positioned at each of the coating stations.

In this embodiment it will be appreciated that the apparatus is modular inasmuch that as many coating stations can be provided in the apparatus and/or activated for the application of the coating to the same sheet material, as is required with respect to the coating speed and/or capacity of the apparatus.

In one embodiment, each of the coating stations is provided to apply the same coating material, hence building up the coating in layers as the substrate passes through the stations thereby depositing a relatively thicker coating than could be applied with a single coating station in one pass of the sheet material.

Alternatively, each coating station can be independently controlled to apply a coating with defined and independent features or provide a conditioning effect. In one embodiment at least one of the coating stations is provided to apply a coating formed from a different material introduced into that coating station. In a further embodiment or in addition, a graduated coating can be applied to the substrate by changing the deposition parameters at at least one of the coating stations to affect the character of the coating. For example, mechanically durable coatings can be obtained by initially using high duty cycle plasma to deposit cross linked material before, in later deposition volumes, using low duty cycle plasmas to deposit well defined highly functionalised surface layers. In a further example, a coating station can be controlled to apply no coating forming material and instead uses the generation of a gas plasma at the deposition volume of the station to activate the substrate surface and improve the adhesion of material subsequently applied at other coating stations.

In one embodiment the apparatus includes means for applying pre and/or post treatments, to the substrate in the case of pre treatment, and the substrate and/or coating in the case of post treatments .

In one embodiment the portion of the sheet material which is coated, in any of the embodiments of the apparatus, extends across the width of the fabric, the width being measured along an axis perpendicular to the longitudinal axis of the sheet material.

In this embodiment, when the width of the sheet material to be coated is known, a required number of material deposition means can be provided in a spaced configuration so as to ensure that an even coating of the material is achieved on the substrate.

The material deposition means can typically be of any desired form which allows the material to be deposited in an atomised manner such as, for example, an ultrasonic nozzle.

In a further aspect of the invention there is provided apparatus for the rapid deposition of a coating onto a moving substrate, said apparatus including a means of introducing an atomised coating forming material into a plasma in a deposition volume in the coating chamber, through which the substrate passes.

Typically the coating material is introduced into the coating chamber using a plurality of interfaced ultrasonic atomisation nozzles arrayed in a configuration across the width of the chamber to ensure a substantially even coating thickness across the width of the treated material.

In one embodiment the atomised coating forming material is introduced into the deposition chamber at the substantially opposite end to the pump outlet so as to maximise the residence time of the atomised material within the deposition volume and to avoid the polymerisation of the material within the ultrasonic atomising nozzles.

In a further embodiment the coating forming material passes from a reservoir to the means of atomisation through a device or series of devices which allow flow rate control and/or measurement.

Preferably the temperature of the liquid coating forming material is regulated so as to prevent volatisation prior to the liquid reaching the atomizers.

In one embodiment the coating forming material is conveyed from its reservoir to the atomizer by virtue of gravitational potential and/or pressure differential between the reservoir and the at least partially evacuated coating chamber. In one embodiment the at least partial evacuation of the chamber is augmented by the application of a positive pressure of an inert gas within the reservoir, above the pressure level of the coating forming material.

In one embodiment the reservoir is in the form of a syringe and the pressure differential between the reservoir and the deposition chamber is augmented by the use of a syringe pump .

In one embodiment the coating chamber includes at least one coating station said coating station including a pair of spaced electrodes defining the deposition volume therebetween and said substrate passes between said electrodes. In one embodiment the electrodes are positioned between a pump outlet and the point of introduction of the coating material in the atomised form.

In one embodiment in each pair of electrodes at a coating station, one electrode is connected to an RF power supply by means of a matching unit, and the other is earthed. In this case the plasma is electrically pulsed by modulating the output of the RF power supply to the live electrode using an external signal generator, such pulsed plasmas having utility in the deposition of the plasma polymer coatings by retaining the functionality of the coating forming material.

In one embodiment the electrodes are subjected to a DC bias voltage with the intention of either reducing or exacerbating the effects of bombardment by charged species from within the plasma.

Typically the coating chamber is evacuated prior to deposition by using a pump via a liquid nitrogen cooled cold trap to a user selected pressure, monitored using a pressure gauge and controlled via feedback to a butterfly valve that throttles the pump.

In one embodiment the deposition chamber may be regulated to a user designated set point by the use of coolant/ heating channels within the apparatus coupled to a heat exchange unit.

Typically the apparatus includes a multiplicity of inlets for the introduction of gases into the coating station(s) . In one embodiment the gases which are introduced are non reactive and are used to, for example, increase the process pressure or facilitate the homogeneous distribution of the atomised coating forming material.

In an alternative embodiment the gases which are introduced are reactive and are used to modify the coating material, modify the surface of the sheet material and/or for cleaning the coating chamber and the coating stations when not in use.

Typically, and in which ever embodiment, or combination of embodiments, the plasma introduced can be referred to as a low pressure plasma.

In a further aspect of the invention, there is provided apparatus for the deposition of a coating onto at least one substrate, said apparatus including at least one coating material deposition means, substrate movement means for moving the substrate to expose at least a portion of the same to the coating material and plasma generating means for generating a plasma to which the said substrate and the coating material are exposed, the deposition means provided to apply the said material in an atomised form and wherein, material, in the atomised form, enters into a vaporisation chamber and passes therethrough, prior to entering the coating chamber in which the plasma and substrate to be coated are located.

In one embodiment, the vaporisation chamber is positioned intermediate the atomiser or each of the atomisers provided in the apparatus and the coating chamber.

In one embodiment, control means are provided to allow the variation of the temperature of the vaporisation chamber. In an alternative, or in addition, control means are provided to allow the pressure within the vaporisation chamber to be controlled.

In one embodiment, the vaporisation chamber is a tube through which the atomised material passes.

In a yet further aspect of the invention there is provided a method for applying a material onto at least one substrate, said method comprising the steps of placing the substrate into a coating chamber, providing material deposition means to supply the material to be applied to the substrates, into the coating chamber, generating a plasma such that the material from the deposition means is exposed to the plasma prior to and/or during application to the substrate and wherein, the deposition means applies the material in an atomised form and said atomised material enters into a vaporisation chamber prior to entering the coating chamber in which the substrates are located.

In one embodiment, when in the vaporisation chamber, the size of the atomised material droplets is altered.

In one embodiment, the atomised material, when it enters the vaporisation chamber is in a liquid form and, when it leaves the vaporisation chamber is still largely/substantially in liquid form but with altered droplet sizes.

In an alternative embodiment, the material which enters the vaporisation chamber is in a liquid form but, when it leaves the vaporisation chamber is a gaseous vapour.

Specific embodiments of the invention are now described with reference to the accompanying drawings wherein ; Figure 1 illustrates a first embodiment of apparatus in accordance with the invention;

Figure 2 illustrates a further embodiment of the apparatus in accordance with the invention;

Figure 3 illustrates a means for guiding the substrate as it is collected on a roll; and

Figure 4 illustrates in schematic form, an illustration of apparatus in accordance with another embodiment of the invention.

Referring firstly to Figure 1 there is illustrated a first embodiment of apparatus in accordance with the invention. The apparatus includes a coating chamber 2, typically manufactured from aluminium and/or stainless steel to avoid corrosion, within which is defined a coating station 4. The coating station 4 includes first and second planar electrodes 6, 8 which are isolated by ceramic spacers 9 from the chamber housing and spaced apart and between which a substrate 10 passes as will be explained in greater detail subsequently.. The electrode 8 is connected to earth 12 and the electrode 14 is connected to a power control means comprising an LC matching unit 16, RF generator 18, pulse generator 20, oscilloscope 22 and passive voltage probe 24. These components in combination cause the generation of a pulsed plasma within the deposition volume 26 defined between the electrodes 6,8. The control means for the operation of the apparatus set the optimum peak power time on and time off characteristics of the pulsed plasma and this is largely dependent upon the deposition rate, coating quality required and the characteristics of the coating forming material, the process pressure and the flow rate within the deposition chamber. As the high throughput of this apparatus results in a low residence time within the deposition volume, a relatively high duty cycle is often necessary. Typical pulsed plasma conditions are peak power at 40W, time on 800 milliseconds and time off 10000 milliseconds.

In addition the 13.56MHz RF power supply is coupled to the live electrode via an automatic LC matching unit which minimises the standing wave ratio (SWR) of the power transmitted from the RF generator to the plasma.

The electrical connection to the reverse of the live electrode is via a single central lead which results in homogeneous plasmas at RF frequencies. The pulse function generator is used to pulse the output from the RF power supply to enable the deposition of well retained pulsed plasma polymers. The pulse width and amplitude of the output from the signal generator are monitored with a cathode ray oscilloscope and connection to a passive voltage probe allows direct monitoring of the plasma.

The substrate 10 is fed in a continuous manner in the general direction 28 through the coating station and passing along the surface or adjacent to the electrode 8, with the substrate fed from the roll 30 and gathered, once coated on the roll 32. In this embodiment the substrate moves in the same direction as the coating material flow but it should be appreciated that the substrate can be moved in the reverse direction if required and/ or may in fact be moved in both directions at different times to allow multi layered coatings to be formed with a layer formed on each pass . Control means in the form of IR sensors 34 and magnetic clutches 36 are provided to allow the tension, speed and guidance of the substrate to be controlled thereby allowing uniformity of the coating on the substrate. Figure 3 illustrates one embodiment of guiding the coated substrate 10 as it is wound onto a roll 32. The inner core 70 of the roll is gripped by an expanding chuck 72 and the substrate sheet comes off the roller, through a slit in the baffles, into the coating chamber 2, where it is guided over the electrodes via the rollers of the tension control and web guiding systems.

The linear raceway 76 supports the roll and is moved by an actuator 90 via a linkage rod 86 in response to deviations in sheet material passage detected by the infra red sensors 34. The aperture 74 is a ceramic bearing lubricated gap between the moving part of the raceway and its static base.

The movement of the roll is controlled by a magnetic particle clutch 78 connected to drive 80 and connected into the chamber 2 via a link rod 82 passing through a rotary and linear vacuum seal 84. The drive for the linear raceway 76 is also controlled via a link rod 86 passing through a rotary seal 88 to a linear actuator 90 which acts as the web guide controller.

The sheet material substrate itself is either wound onto cores that can be directly fitted into the chamber or are provided on standard cores that are fitted onto a shaft as described above with the mechanically expanding lugs. The guiding of the sheet material in an effective manner ensures consistency of coating especially with materials that possess a significant degree of elasticity or those of a woven or knitted nature. Any deviation in the sheet material passage is sensed by the infra red sensors 34 and the roll 32 can be moved in the appropriate manner. This system can be fitted to both rollers but only used on one roller at a time to allow the direction of movement of the substrate to be reversed as required. The tension of the sheet material is constantly monitored and the signals fed into a controller that continuously adjusts the torque applied to the rollers via the clutch 78 and drive 80. The material which is to be used to form the coating is held in a liquid form in a reservoir 38 which can be a syringe or a vessel with inlets for admitting a positive pressure of inert gas above the liquid, and supplied in a liquid or liquid solid slurry form to a series of ultrasonic nozzles 40 via flow meter 42 so as to allow the continued and predictable flow and supply of the material. The nozzles are typically provided with broadband power supplies and interfaced with the coating chamber using O ring sealed fittings which allow leak tight fitting with relatively easy removal for maintenance purposes. The flow meter is typically a unit consisting of a liquid mass flow controller or a coriolis meter coupled to a control valve. The nozzles are typically spaced apart across the width of the sheet material so as to ensure an even supply of the material to form the coating as the material is sprayed 44 in an atomised manner from the nozzles onto the substrate as shown. The pipework from the reservoir to the nozzles may require temperature control in order to avoid volatisation as volatilisation of the monomer before it reaches the ultrasonic nozzles has been known to interfere with the function of liquid flow control. At the same time gas can be introduced in to the coating chamber via gas inlets, 46, one of which is shown. The gas which is introduced can be non reactive or reactive depending upon the purpose required at any instant during the coating process.

In addition and to ensure that the atomised coating material 44 is influenced to move in the direction 28 along the chamber as it moves towards the substrate 10 in the deposition volume 26, a pump 52 is provided which causes fluid flow in the chamber generally in the direction 28. The pump is typically connected to the chamber 2 via a butterfly valve 54 and a cold trap 50. In one embodiment the chamber is differentially pumped in that the deposition volume is provided with pump 52 and the substrate reel areas are provided with different pumps, such as pumps 48 and 56. This arrangement will help to prevent substrate contamination before and after the application of the coating material onto the substrate and permits the coating of relatively highly hygroscopic substrates where the out gassing of the entire roll into the discharge volume would normally preclude plasma treatment. In this case the substrate containing volume may be heated to enhance water removal from the substrate prior to its treatment and prevent water reabsorption.

The cold trap is typically formed by liquid nitrogen and enables the attainment, rapidly, of base pressure after the substrate insertion and eliminates the backflow of contaminants from the pump. This is again especially useful with hygroscopic substrates e.g hydrophilic polymers such as nylon and textiles that can outgas a considerable amount of water.

The gas pressure monitoring and control in one embodiment uses a manometer pressure gauge and provides feedback to a pressure controller that by throttling the butterfly valve maintains the pressure chamber at a user defined set point.

The positioning of the nozzles upstream of the coating chamber ensures that the time for which the atomised material, typically a monomer, is in the deposition volume 26 is maximised and also prevents the plasma from causing polymerisation at the nozzles or within the same which could block the nozzles.

Figure 2 illustrates a further embodiment of the apparatus. In this case the same general components are utilised but in this case whereas in Figure 1 the coating chamber included a single coating station defined around the deposition volume 26, the coating chamber of Figure 2 includes a plurality of coating stations 60,62,64, each having its own pair of electrodes 6,8 and deposition volume 26 and array of ultrasonic nozzles 40. Once again the substrate is fed from roller 30 to roller 32 but in this case additional guides 66 are provided to ensure that the substrate passes in the required manner and at the required tension speed and the like through each of the coating stations. In this case each coating station can be independently controlled such that for example, each station may apply the same material in the same plasma conditions to simply add a layer of the coating to increase the thickness of the same as the substrate passes therethrough, or one or each of the coating stations is varied in terms of the coating applied such that for example, coating station 60 applies no material but conditions the substrate, station 62 applies a first material with a pulsed plasma and coating station 64 applies a second material in a pulsed plasma to provide a multilayered coating. This arrangement is modular in as much as any number of coating station modulus can be provided in combination and/or activated at any given time to provide a coating process as required for the particular substrate being coated at that time.

One example of the coating process is as follows:

1. The deposition chamber is cleaned before treatment using an appropriate plasma generated to remove the sources of contamination such as air, oxygen, an oxygen mixture.

2. The roll of sheet material substrate is inserted into the coating chamber forming roll 30 and a length unwound and fed to the roller 32.

3. The chamber 2 is shut and the apparatus pumped down to base pressure via the liquid nitrogen trap. If required the chamber can be heated to speed up this process .

4. The flow controller is readied for treatment and any air or gas in the lines are removed by forcing coating forming material through the purge connection into a captured vent. The detected flow rate is allowed to fall to zero.

5. The ultrasonic nozzles are activated by switching on the broadband ultrasonic generators. The flow of coating material passes from the reservoir to the ultrasonic nozzles at a preset flow rate using the flow controllers. The atomisation of coating forming material then commences.

6. The butterfly valve 54 is closed and the chamber pressure rises above the correct process pressure. The butterfly valve then reopens slowly and continuously adjusts in response to the monitored pressure until a steady state is achieved where the butterfly valve position and hence the flow rate are near constant.

7. Upon consistent attainment of the process pressure the pulsed plasma is ignited.

8. Once the pulsed plasma has been established the web starts moving across the deposition volume.

9. Once the roll has been coated the process control is turned off the RF power and web systems become inactive and the butterfly valve reopens fully. The flow of coating forming ;liquid to the ultrasonic atomisers is also stopped and after a short time to allow the atomisers to empty and the ultrasonic generators are switched off.

10. After the apparatus has been safely evacuated to base pressure the chamber can be vented to atmosphere and the roll of the coated substrate removed.

The apparatus shown in Figure 4 is similar to that of Figures 1 -3 of the application and comprises a substrate 102 which in this case is fed from a reel 104 to reel 106 across a distance within the coating chamber 108 of the apparatus. Into the coating chamber is applied a coating material 110 which, in accordance with this invention, is applied via a vaporisation chamber 112 from nozzle 114. The operation of this particular part of the apparatus is described in more detail later. Also provided is a control means 116 to allow the control and tensioning of the feed of the substrate 102 to the coating chamber and control means 118 to allow the control of the environment within the coating chamber 108 in terms of gas, vacuum, pumping and the like and these two aspects have been dealt with in more detail in the co-pending application. Further control means 120 are provided to allow the control of the plasma generating means in the form of electrodes 122 and 124 which generate a plasma within the coating chamber 108 and to which the material 110, which passes from the vaporisation chamber 112 is exposed.

In the previous embodiment the material leaves the atomising means 114 directly into the coating chamber. However, in accordance with this embodiment, the material 110 leaves the atomisation means in an atomised form of liquid droplets and passes directly into the vaporisation chamber 112. In one mode of operation, the vaporisation chamber may be set to make no difference to the atomised material and the same simply passes through the vaporisation chamber and enters the coating chamber 108 in an unchanged condition.

However, the vaporisation chamber does provide the apparatus with the ability to alter the condition of the atomised material. This can be achieved by providing control means 126 which allow the temperature in the vaporisation chamber 112 to be altered and control means 128 which allow the pressure in the vaporisation chamber 112 to be adjusted. One or both of these control means can be used to bring about the change in condition.

In one arrangement, the temperature and the pressure can be altered to bring about changes in the characteristics of the atomised coating material including mean droplet size and the proportion of the atomised material which is in the gaseous state prior to entry into the coating chamber.

In one example, the generation of a temperature in the vaporisation chamber which is significantly above the boiling point of the coating material may result in the complete conversion of the atomised droplets into a flux of vapour. The modification of the physical parameters of the coating material supplied to the coating chamber has potential utility in optimizing the deposition rate, chemical characteristics, coherency and penetration of the coating material when applied to the substrate. For example, if the surface conditions of a particular substrate are known, the material which is deposited from the vaporisation chamber may be conditioned within the vaporisation chamber so that the same specifically matches and meets the requirements of the substrate. The vaporisation chamber therefore provides a "fine tuning" effect. The characteristics of the coating and/or its penetration into, for example, porous or woven substrate could be optimised, as the degree of polymerisation occurring within the droplets, prior to and subsequent to, condensation onto the substrate and the atomised materials infiltration within the substrate are likely to exhibit a dependence on the droplet size.

In one embodiment, the vaporisation chamber is a heated column and/or can be differentially pumped and, if required, baffles can be provided within the vaporisation chamber.

The apparatus and method in accordance with this embodiment therefore provide an ability for fine tuning of the apparatus as described in terms of adapting the atomised material into a particular form which may suit application to a particular, identified, substrate. The apparatus as herein described therefore represents a significant advance in the development of the applications of coatings onto substrates such as sheet material substrates fed from rollers in particular but can also be of advantage with regard to other forms of substrates.

Claims

1. Apparatus for the deposition of a coating onto at least one substrate said apparatus including at least one coating material deposition means, substrate movement means for moving the substrate to expose at least a portion of said substrate to the coating material and plasma generating means for generating a plasma to which the said portion of substrate and a coating material are exposed and wherein the deposition means is provided to apply the said material in an atomised form into a coating chamber in which the plasma is generated such that the deposited material is exposed to the plasma prior to and/or once applied to the said portion of the said substrate.

2. Apparatus according to claim 1 wherein the plasma is generated in a pulsed manner.

3. Apparatus according to claim 1 wherein the substrate is a sheet material and is fed through the apparatus from a feed roll to a re-wind or collection roll to allow a portion of the sheet material to be exposed to the coating apparatus.

4. Apparatus according to claim 3 wherein the sheet material is fed through the apparatus in a continuous manner.

5. Apparatus according to claim 3 wherein the sheet material is fed through the apparatus in a stepwise manner.

6. Apparatus according to claim 3 wherein the apparatus includes means for controlling any or any combination of the tension, speed and alignment of the web of sheet material.

7. Apparatus according to claim 1 wherein the apparatus includes a plurality of coating stations, each coating station including deposition means to allow a coating material to be selectively introduced into a deposition volume and a plasma deposition means for generating a plasma at each deposition volume.

8. Apparatus according to claim 7 wherein at at least one coating station, there is applied a coating and/or conditioning effect to the portion of the substrate which is positioned at each of the said coating stations.

9. Apparatus according to claim 1 wherein the apparatus is modular inasmuch that a plurality of coating stations are selectively provided and/or activated for the application of the coating to said substrate.

10. Apparatus according to claim 9 wherein each of the coating stations is provided to apply the same coating material and/or conditioning effect.

11. Apparatus according to claim 9 wherein each coating station is independently controlled to apply a coating which is independently controlled with regard to that applied by the other coating stations.

12. Apparatus according to claim 1 wherein the apparatus includes means for applying pre and/or post treatments, to the substrate in the case of pre-treatment and a substrate and/or coating in the case of post-treatments .

13. Apparatus according to claim 1 wherein the portion of the substrate which is coated extends across the width of the substrate.

14. Apparatus for the deposition of a coating onto a moving substrate, said apparatus including a means of introducing an atomised coating forming material into a plasma in a deposition volume in the coating chamber through which the coating forming material passes.

15. Apparatus according to claim 14 wherein the coating material is introduced into the coating chamber using a plurality of ultrasonic atomisation nozzles arranged in a configuration across the width of the coating chamber.

16. Apparatus according to claim 15 wherein the atomised coating forming material is introduced into the deposition chamber at an end substantially opposite to a pump outlet so as to maximise the residence time of the atomised material within the deposition volume.

17. Apparatus according to claim 14 wherein the coating forming material passes from a reservoir to the means of atomisation via a device or series of devices which allow flow rate control and/or measurement.

18. Apparatus according to claim 17 wherein the coating forming material is conveyed from its reservoir to the atomiser by virtue of gravitational potential and/or pressure differential between the reservoir and the at least partially evacuated coating chamber.

19. Apparatus according to claim 18 wherein the at least partial evacuation of the chamber is augmented by the application of a positive pressure of an inert gas within the reservoir above the pressure level of the coating forming material.

20. Apparatus according to claim 19 wherein the reservoir is in the form of a syringe and the pressure differential between the reservoir and the deposition chamber is augmented by the use of a syringe pump.

21. Apparatus according to claim 14 wherein the coating chamber includes at least one coating station which in turn includes a pair of spaced electrodes defining a deposition volume therebetween and said substrate passes between said electrodes.

22. Apparatus according to claim 21 wherein the electrodes are positioned between a pump outlet and a point of introduction of the coating material in the atomised form.

23. Apparatus according to claim 21 wherein a first electrode is connected to an RF power supply and a second electrode is earthed.

24. Apparatus according to claim 23 wherein the plasma generated is electrically pulsed by modulating the output of the RF power supply to the live electrode.

25. Apparatus according to claim 21 wherein the electrodes are subjected to a DC bias voltage.

26. Apparatus according to claim 14 wherein the coating chamber is evacuated prior to deposition using a pump to supply liquid nitrogen.

27. Apparatus according to claim 14 wherein the apparatus includes a plurality of inlets for the introduction of selected gases into the coating station or stations.

28. Apparatus for the deposition of a coating onto at least one substrate, said apparatus including at least one coating material deposition means, substrate movement means for moving the substrate to expose at least a portion of the same to the coating material and plasma generating means for generating a plasma to which the said substrate and the coating material are exposed, the deposition means provided to apply the said material in an atomised form and wherein the coating material, in the atomised form, enters into a vaporisation chamber and passes therethrough, prior to entering the coating chamber in which the plasma and substrate to be coated are located.

29. Apparatus according to claim 28 wherein the vaporisation chamber is positioned intermediate the atomiser, or each of the atomisers provided in the apparatus, and the coating chamber.

30. Apparatus according to claim 28 wherein control means are provided to allow the variation of the temperature of the vaporisation chamber.

31. Apparatus according to claim 28 wherein control means are provided to allow the pressure within the vaporisation chamber to be controlled.

32. A method for applying a material onto at least one substrate, said method comprising the steps of placing the substrate into a coating chamber, providing material deposition means to supply the material to be applied to the substrate into the coating chamber, generating a plasma such that material from the deposition means is exposed to the plasma prior to and/or during application to the substrate and wherein the deposition means applies the material in an atomised form and said atomised material enters into a vaporisation chamber prior to entering the coating chamber in which the substrates are located.

33. A method according to any preceding claim wherein once in the vaporisation chamber the size of the atomised material droplets is altered.

34. An apparatus for the rapid deposition of coatings onto a moving substrate web that includes a means of introducing an atomised coating forming material into a plasma deposition chamber containing the substrate.

35. An apparatus according to Claim 34 wherein the coating forming material is introduced into the deposition chamber using a plurality of interfaced ultrasonic atomisation nozzles arrayed across the width of the deposition chamber in such a manner as to ensure a substantially even coating thickness across the width of the treated material.

36. Apparatus according to claim 34 wherein the coating forming material is a liquid or liquid/solid slurry.

37. Apparatus according to claim 34 wherein the plasma is pulsed low pressure plasma.

38. An apparatus according to claim 1 wherein the temperature of the coating forming material is regulated so as to prevent its volatilisation before it reaches the atomizers.

39. An apparatus according to claim 34 wherein the plasma deposition chamber possesses one r more deposition volumes, each described by a pair of electrodes situated largely between a pump outlet and the points of introduction for the atomised coating forming material.

40. An apparatus according to claim 39 wherein the plasma deposition chamber contains a series of sequential deposition volumes, each possessing an array of atomizers and a pair of electrodes, enabling the deposition of multiple onto a moving substrate during a single pass.

41. An apparatus according to claim 40 wherein each deposition volume deposits a substantially identical coating, enabling the deposition of thicker coatings of a given coating forming material onto a moving web than would be possible using a single deposition volume.

42. An apparatus according to claim 40 wherein each deposition volume may deposit a different coating forming material.

43. An apparatus according to claim 40 wherein variations in deposition conditions between each deposition volume are used to create gradated multi-layers of the same, or different, coating forming materials.

44. An apparatus according to claim 36 wherein the temperature of the deposition chamber is regulated to a user designated set-point by the use of coolant/heating channels within the apparatus coupled to a heat exchange unit.

45. An apparatus according to claim 34 wherein the substrate comprises a web of material (plastic, textile, knitted, non-woven, woven, moved continuously through the plasma deposition volume(s) with a reel-to-reel apparatus.

46. An apparatus according to claim 45 wherein the apparatus includes means for improving the consistency of coatings deposited onto materials possessing significant elasticity or those of a woven/knitted nature where the spacing between fibrils governs the penetration of the plasma.