Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32431—Constructional details of the reactor
  • H01J37/32798—Further details of plasma apparatus not provided for in groups H01J37/3244 - H01J37/32788; special provisions for cleaning or maintenance of the apparatus
  • H01J37/32816—Pressure
  • H01J37/32825—Working under atmospheric pressure or higher
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
  • H05H1/00—Generating plasma; Handling plasma
  • H05H1/24—Generating plasma
  • H05H1/2406—Generating plasma using dielectric barrier discharges, i.e. with a dielectric interposed between the electrodes
  • H05H1/2441—Generating plasma using dielectric barrier discharges, i.e. with a dielectric interposed between the electrodes characterised by the physical-chemical properties of the dielectric, e.g. porous dielectric
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/12—Chemical modification
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/12—Chemical modification
  • C08J7/123—Treatment by wave energy or particle radiation
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
  • H01J37/32018—Glow discharge
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
  • H01J37/32348—Dielectric barrier discharge
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32431—Constructional details of the reactor
  • H01J37/32733—Means for moving the material to be treated
  • H01J37/32752—Means for moving the material to be treated for moving the material across the discharge
  • H01J37/32761—Continuous moving
  • H01J37/3277—Continuous moving of continuous material
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
  • H05H2242/00—Auxiliary systems
  • H05H2242/20—Power circuits
  • H05H2242/26—Matching networks

Definitions

• the present invention relates to a method for surface treatment of a material, in particular of a triacetyl cellulose film.
• the present invention relates to a surface treatment apparatus.
• a method and apparatus for surface treatment of a material are disclosed in American patent US6,512,562, which discloses a protective film for a polarizing plate and a method and apparatus for producing such a film.
• an atmospheric pressure glow discharge plasma is being used to treat the protective film surface.
• polarising films which may be used in the production of e.g. liquid crystal displays
• a polarising film such as polyvinyl alcohol (PVA) may be laminated with two triacetyl cellulose (TAC) films.
• PVA polyvinyl alcohol
• TAC triacetyl cellulose
• the TAC film surface may be pre treated with alkali (saponification). This allows formation of H-bridges with the polymer for proper bonding of the two materials.
• alkali sodium bicarbonate
• a disadvantage of this process is the use of wet material with the associated handling and waste problems.
• the PVA film is pretreated before being laminated with two TAC films.
• Japanese patent application JP2002155371 discloses a method and system for manufacturing a semiconductor device.
• a transparent conductive film is deposited on a semiconductor substrate using a plasma generated in an atmosphere comprising argon, helium, neon, and/or xenon. Summary of the invention
• the present invention seeks to provide a treatment method and apparatus for triacetyl cellulose (TAC) film in particular, which does not have the disadvantages of the known methods and systems described above.
• a particular disadvantage is the formation of a white deposit upon APG treatment of an TAC film in the presence of oxygen.
• a method for surface treatment of a triacetyl cellulose film comprising generating an atmospheric pressure glow discharge plasma in a treatment space, and exposing the surface of the triacetyl cellulose film to the atmospheric pressure glow discharge plasma in the treatment space for a predetermined amount of time, in which the atmospheric pressure glow discharge plasma is generated in a substantially oxygen free atmosphere in the treatment space comprising a mixture of a noble gas, such as argon, and an inert gas, e.g. nitrogen.
• the atmosphere may comprise at least 2% of nitrogen, e.g. 20% of nitrogen.
• the triacetyl cellulose film is exposed to an atmospheric pressure glow discharge plasma which is stabilized according to methods described in for example US6774569B, or EP-A-1383359.
• the triacetyl cellulose film is exposed to an atmospheric pressure glow discharge plasma, where the plasma is e.g. stabilized by an LC matching circuit.
• the triacetyl cellulose film is exposed to a pulsed atmospheric pressure glow discharge plasma.
• a pulsed discharge plasma is another method for the control of the plasma formation and uniformity and also provides for a method to control the plasma effectiveness in relation to for example the treatment time wanted or the line speed range which is available in the plasma generation set-up
• the method may further comprise laminating the treated triacetyl cellulose film to a polarizing film, such as polyvinyl alcohol film, to efficiently provide a polarizing plate film, without the need for further treatment of the films.
• a polarizing film such as polyvinyl alcohol film
• Other methods of combining the triacetyl cellulose film to the polarizing film, such as attaching, contacting, bonding, etc. may also be used.
• the present invention relates to a surface treatment apparatus, comprising a first electrode and a second electrode for generating an atmospheric pressure glow discharge plasma in a treatment space between the first and second electrode, the first and second electrode comprising a dielectric barrier on a surface directed towards the treatment space, in which the surface treatment apparatus is further arranged to generate the atmospheric pressure glow discharge plasma in a substantially oxygen free atmosphere in the treatment space.
• the electrodes can be provided with a dielectric barrier in various arrangements. In one arrangement the dielectric barrier of at least the second electrode is formed by a triacetyl cellulose film. In another arrangement both electrodes are provided with TAC film as a dielectric barrier. In still another arrangement the electrodes can be provided with a dielectric barrier.
• PET polyethyleneterephthalate
• PEN polyethylenenaphthalate
• PTFE polytetrafiuoroethylene
• PE polyethylene
• ceramic such as silica or alumina, or combinations of these, also microporous dielectric materials attached to the electrodes can be used.
• triacetyl cellulose the film may be moveable over the associated electrode which might be a bare electrode or an electrode provided with a dielectricum, allowing for a continuous treatment process.
• the other electrode may also be provided with a stationary or moveable film, e.g. comprising polyethylene terephthalate (PET) or other polymers, as dielectric barrier.
• PET polyethylene terephthalate
• both electrodes use a triacetyl cellulose film as dielectric barrier, allowing a higher throughput.
• the surface treatment apparatus may be arranged to generate the atmospheric pressure glow discharge plasma in the atmospheres as defined in the above described method embodiments.
• the surface treatment apparatus may in a further embodiment comprise a transport device for transporting the triacetyl cellulose film over the electrode.
• the transport device may comprise a tensioning mechanism for keeping the triacetyl cellulose film in close contact with the electrode.
• the surface treatment apparatus further comprises a laminating unit positioned downstream of the treatment space, in which the laminating unit is arranged to laminate the treated triacetyl cellulose film and a polarizing film, such as a polyvinyl alcohol film.
• a laminating unit positioned downstream of the treatment space, in which the laminating unit is arranged to laminate the treated triacetyl cellulose film and a polarizing film, such as a polyvinyl alcohol film.
• the present invention also relates to a surface treatment apparatus, comprising a first electrode and a second electrode for generating an atmospheric pressure glow discharge plasma in a treatment space between the first and second electrode, the first and second electrode comprising a dielectric barrier on a surface directed towards the treatment space, in which the surface treatment apparatus is further arranged to generate the atmospheric pressure glow discharge plasma in a substantially oxygen free atmosphere in the treatment space, in which the surface treatment apparatus is arranged to generate a stabilised atmospheric pressure glow discharge plasma in the treatment space.
• the means for controlling the plasma comprise an LC matching network formed by a matching inductance and a system capacity formed by the two electrodes and the discharge space, and a pulse forming circuit in series with at least one of the electrodes.
• Fig. 1 shows a schematic diagram of a first embodiment of a surface treatment apparatus according to the present invention
• Fig. 2 shows a schematic diagram of a second embodiment of a surface treatment apparatus according to the present invention
• Fig. 3 shows a graph showing the results of water contact angle measurements for a number of tests using the surface treatment method according to the present invention
• Fig. 4 shows a graph showing the results of water contact angle measurements for a number of control tests using an air corona surface treatment method
• Fig. 5 shows a schematic diagram of an apparatus for producing a polarising plate using a treated film
• Fig. 6 shows a schematic view of a stabilising arrangement used in an embodiment of the present invention.
• a surface treatment system is shown according to a first embodiment of the present invention.
• the system comprises a parallel plate double dielectric barrier discharge geometry, having a first or upper electrode 16 and a second or lower electrode 17.
• the electrodes 16, 17 define a treatment space 15, which can be constructed according to specific requirement. Both the electrodes 16, 17 can have a width of for example 1, 2, 3, 4 cm and more while also various electrodes in series with each other can be used thereby increasing the possible treatment time.
• the length in this respect is defined as the length of the electrode 16, 17 perpendicular to the treatment direction of a web 10 to be treated, i.e. perpendicular to the drawing surface of Fig. 1.
• the electrodes 16, 17 In order to have a good and uniform plasma, the electrodes 16, 17 have to be strictly parallel over the total length, without this a stable plasma cannot be obtained. As long as the electrodes are parallel and remain parallel during the usage there is no limitation in length. The length is mainly dependant on the width of the web 10 which should be treated, so any length from 10cm (test purpose) to as long as 1.5 m or even 2.0m and 2.5m and more can be used.
• the electrodes 16, 17 may be covered with a dielectric discharge barrier like for example polyethyleneterephthalate (PET), polyethylenenaphthalate (PEN), polytetrafluoroethylene (PTFE), polyethylene (PE), ceramic such as silica or alumina, or combinations of these.
• the upper electrode 16 is provided with a dielectric barrier layer or foil on its surface directed towards the treatment space, while for the lower electrode 17, in addition to an optional dielectric layer fixed to electrode 17, the dielectric barrier layer is provided by a triacetyl cellulose (TAC) film or web 10 to be treated.
• TAC triacetyl cellulose
• the electrode gap between the dielectric foils of the electrodes 16, 17 is not limited to any particular distance but should be preferably below 5 mm, preferably below 2 mm or more preferably below 1.5 mm and can be typically 1 mm or even lower.
• the TAC film 10 is transported using a transport device including a supply roll 20 and a take up roll 21, via further rollers 22...25.
• the further rollers 22...25 are provided in an s-wrap configuration on both sides of lower electrode 17, and form a tensioning mechanism which allows alignment adjustment of the TAC film 10 over the lower electrode 17.
• the upper electrode 16 is configured to have a film 10' as dielectric barrier, which is transported from a supply roll 20' to a take up roll 21 '.
• the electrodes 16, 17 are covered with a dielectric foil 10,
• the function of the foils 10, 10' is thus to control the plasma stability and to have those foils 10, 10' exposed to the plasma in treatment space 15.
• the thickness of the dielectric foils used in general and of the TAC foils more in particular is not limited to any specific value and is merely dictated by the application for which it is used. In general the foils have a thickness of below 150 micrometer and preferably the thickness is below 100 micrometer for example 90 or 80 ⁇ m.
• the atmospheric pressure glow discharge plasma can be generated according to the methods known in the art. Preferred plasma's are those which are stabilised for example according to the principles set forth in for example US6774569B, or EP-A- 1383359. An example of a preferred embodiment of a plasma stabilisation and control arrangement is shown in Fig. 6.
• an impedance matching arrangement is provided in the plasma control arrangement, in order to reduce reflection of power from the electrodes 16, 17 back to the power supply (i.e. AC power supply means 35 and intermediate transformer stage 36).
• the impedance matching arrangement may be implemented using a known LC parallel or series matching network, e.g. using a coil with an inductance of L mato hm g and the capacity of the rest of the arrangement (i.e. formed mainly by a parallel impedance 43 (e.g. a capacitor) and/or the capacitance of the discharge space 15 between the electrodes 16, 17).
• a parallel impedance 43 e.g. a capacitor
• such an impedance matching arrangement cannot filter high frequency current oscillations, which may occur during plasma breakdown.
• the high frequency supply 35 is connected to the electrodes 16, 17 via intermediate transformer stage 36 and matching coil with inductance L matc hmg- Furthermore, a pulse forming circuit 40 is connected to the lower electrode 17.
• a further impedance 43 is connected in parallel to the series circuit of electrodes 16, 17 and pulse forming circuit 40.
• the pulse forming circuit 40 is arranged to obtain the desired pulse shaping in order to suppress (or enhance) instabilities, which may possibly form at the pulse breakdown (onset of plasma pulse) and also to suppress (or enhance) instabilities at the end of the plasma pulse (after the plasma pulse maximum.
• the main idea is to use the pulse forming circuit 40 in series with a resonant LC series circuit.
• the serial resonant circuit will be unbalanced by the need of large frequency current (due to the forcing of the power supply 35 to provide large currents) and the displacement current provided from the power supply will tend to drop.
• the simplest implementation of the pulse forming circuit 40 is a capacitor in series with the plasma electrodes 16, 17. In order to be efficient its capacity must be comparable with the plasma reactor capacity.
• the pulse forming circuit 40 can be formed out of several components. So for example it can be composed out of a choke coil in parallel with a capacitor.
• the circuit 40 of the capacitor and choke are chosen to be resonant at the frequency of the power supply 35.
• the circuit 40 is composed out of a capacitor in parallel with a series resonant LC circuit, comprising a choke and a further capacitor. Also in this case the characteristics of the components are chosen in such a way, that the circuit is resonant to the frequency of the power supply 35.
• a gas or a gas mixture has to be introduced in the electrode gap 15.
• this mixture is mixed on beforehand and subsequently injected in between the electrode gap (treatment space) 15.
• the gases preferably used in this invention are noble gases like for example neon, argon, helium and inert gases like for example nitrogen.
• mixtures of gases can be used like for example mixtures of a noble gas and an inert gas.
• a continuous treatment of a web 10 is preferable and therefore the web to be treated preferably has a continuous speed over the electrode 16, 17. This speed is dependant on the electrode width and on the electrode arrangement and the treatment time one wants to achieve. So in case of more electrodes placed behind each other the line speed can be higher giving the same treatment time as with only one electrode. Treatment times as long as 4 seconds give very good results, but already significant results can be obtained with 1 second treatment time or less.
• the line speed of the bottom web 10 and that of the upper web 10' may be the same or may be different. Line speeds are possible of more than lOcm/min to lm/min to over 30m/min and higher as stated above, dependent on the configuration used. Wrinkling of one of the foils 10, 10' is to be prevented because a condition to maintain a stable and uniform glow discharge is that the foil 10, 10' should have a uniform and intimate contact with the associated electrode 16, 17.
• Another attention point in the double layer system of Fig 2 is the amount of volatiles evaporating from the web materials used. It was observed, that stable atmospheric glow plasma's could be obtained using industrial available web materials like PET, PEN, TAC and the like and no deterioration occurred by the presence of water vapor or solvents evaporating from the dielectric barriers (foils 10, lO'at the electrode 16, 17 surface).
• plasma stability need not to be deteriorated by substituting one PET or PEN foil 10' by a second TAC film or foil 10'. In such a case the dielectric capacity of the dielectric barrier discharge gap is somewhat changing and therefore the pulse network controlling has to be adjusted slightly.
• the TAC film treated according one of the embodiments of this invention has a very low WCA. This low WCA cannot be reached using common available techniques. The low contact angle remains also after aging for several days, meaning, that the treated material can be stored until further processing.
• a specific embodiment of such manufacturing is shown schematically in Fig 5.
• the treated TAC is combined with a polarising film 11 , as shown in the simplified schematic view of Fig. 5.
• the polarising film 11 can be for example polyvinyl alcohol (PVA) film.
• PVA polyvinyl alcohol
• This film is provided from a source roll 31.
• the treated TAC films 10, 10' are provided from supply rolls 32, 33, respectively, or may be provided directly from the treatment apparatus as described above.
• the three films 10, 11, 10' are then laminated in a lamination unit 30, to produce a polarizing plate film 12.
• the lamination unit 30 may be of a known type, and may use pressure and/or heat to bond the three films 10, 11, 10' together.
• the set-up consists of a parallel plate double dielectric barrier discharge geometry (Fig 2) with a total electrode length of 15 cm and an electrode width of 4 cm (dimension in treatment direction).
• the electrode gap 15 between the dielectric foils is typically 1 mm.
• Both electrodes 16, 17 are covered with a dielectric foil to sustain the plasma stability, see the description above.
• the function of the foils is thus to control the plasma stability and to have those foils exposed to the plasma.
• the top electrode foil used comprises of a 90 um PET foil whereas the bottom foil is 80 um TAC film. The choice to mount the TAC film on the bottom roll to roll system is because of ergonomics.
• dielectric barrier discharge (DBD) system the metal electrodes 16, 17 are powered by a high frequency power generator 35 comprising of an RFPP generator LFlOa connected to an impedance matching transformer 36.
• the output of the matching transformer 36 is connected to a series resonant network, similar to the structure described with reference to Fig. 6 above.
• the APG reactor 15, 16, 17 is connected parallel to the capacitor 43.
• the resonance frequency of the system is tuned at about 120 kHz.
• the displacement current control operates within each halve cycle of the electric field (within pulse train).
• the generator 35 is set to slave mode and driven by external pulse control unit (not shown).
• the external pulse control unit can either be computer controlled or consist of two function generators where one of these generators provides the triggering of pulse trains for the other generator.
• the pulse trains consist of a series of AC pulses defined as: T 0n followed by a period of no electric field T 0 ff.
• the pulse train duration can be set from 10 microseconds to 1 second.
• the pulse on time was chosen in the millisecond range.
• the gas is mixed and subsequently injected from the left hand side in between the electrode gap.
• Line speed of the bottom roll to roll (with TAC film) was varied, whereas the line speed of the top roll to roll was set to the lowest line speed being 10 mm/min.
• % duty cycle (pulse on time divided by the pulse off time together with the pulse on time
• Fig. 3 shows the results of the water contact angle measurements for the various tests.
• the TAC films 10 were treated in a table corona unit equipped with six alumina electrodes, as known to the skilled person.
• the TAC film 10 was put on an alumina coated drum electrode rotating with a speed V. Further parameters are listed in the following table (No. rev giving the number of revolutions of the coated drum electrode resulting in the total treatment time in second(s)).
• the polarising film 11 was a polyvinyl alcohol (PVA) film 11, which is provided from a source roll 31.
• the treated TAC film 10, 10' is provided from supply rolls 32, 33, respectively,.
• the three films 10, 11, 10' were laminated in a lamination unit 30, to produce a polarizing plate film 12. Because of the APG treatment of the TAC films 10, 10', adhesion to the PVA film 11 was achieved without further pre- treatment of the TAC films 10, 10' or PVA film 11.
• the lamination unit 30 was a known type, using pressure and heat to bond the three films 10, 11, 10' together.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• Physics & Mathematics (AREA)
• Analytical Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Treatments Of Macromolecular Shaped Articles (AREA)
• Chemical Vapour Deposition (AREA)
• Lining Or Joining Of Plastics Or The Like (AREA)

Priority Applications (1)

Applications Claiming Priority (3)

Publications (1)

Family

ID=36593747

Family Applications (1)

Country Status (3)

Families Citing this family (13)

Family Cites Families (10)

• 2007
  • 2007-02-02 EP EP07715860A patent/EP1979400A1/de not_active Withdrawn
  • 2007-02-02 WO PCT/NL2007/050040 patent/WO2007089146A1/en active Application Filing
  • 2007-02-02 JP JP2008553191A patent/JP2009525381A/ja active Pending

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events