Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
  • B05D3/14—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by electrical means
  • B05D3/141—Plasma treatment
  • B05D3/142—Pretreatment

Definitions

• the present invention relates to a method for activating web-shaped Materials, especially plastic and metal foils using an atmospheric Plasma.
• finishing steps such as printing, coating, painting, Gluing, etc.
• plastic and metal foils if one sufficient wettability with solvent or water-based printing inks, Lacquers, primers, adhesives, etc. is given. In general, therefore, in or Corona treatment performed offline with the film processing.
• the web-shaped Materials exposed to an evenly distributed electrical discharge Prerequisite are two working electrodes, one with a dielectric material (Silicone, ceramic) is encased. There is a high between the two electrodes AC voltage with a frequency typically between 10 and 100 kHz, so that an even spark discharge takes place.
• the one to be treated Material is passed between the electrodes and exposed to discharge. This results in "bombardment" of the polymer surface with electrons, the energy of which is sufficient to form bonds between carbon-hydrogen and break up carbon-carbon.
• the radicals formed react with the corona gas and thereby form new functional groups.
• the corona treatment has significant disadvantages. So it happens especially at higher ones Orbital velocities to a parasitic backside corona discharge if the sheet-like materials do not rest on the roller-shaped electrode. Furthermore, the corona treatment leads to a clear electrostatic Charging the sheet-like materials that are winding the materials complicates the subsequent processing steps, such as painting, printing or Adhesion hinders and especially in the production of packaging films is responsible for powdered materials such as coffee or spices stick to the film and in the worst case contribute to leaky sealing seams. After all, the corona treatment is always a filament discharge that does not homogeneously closed surface effect. You also ask with time found that a loss of surface properties due to the migration of Foil additives occur and that a molecular rearrangement based on a Minimization of surface energy takes place.
• Corona treatment is limited to thin substrates such as plastic films and papers. For thicker materials, the total resistance is between the Electrodes too large to ignite the discharge. But it can also be too single punctures come. Corona discharge is not to be used for electrically conductive plastics. Dielectric electrodes also show metallic or metal-containing webs often only have a limited effect. The Dielectrics can burn out easily due to the permanent stress. This is particularly the case with silicone-coated electrodes. Ceramic electrodes are very sensitive to mechanical stress.
• surface treatments can also be carried out by Flames or lights are carried out.
• the flame treatment is common at temperatures around 1700 ° C and intervals between 5 and 150 mm. Because the foils temporarily reach high temperatures of around 140 ° C effective cooling must be carried out.
• the treatment results, which are already good, can be compared to the Cooling roller are brought to an electrical potential that the ions of the flame accelerated to the web to be treated (polarized flame).
• a treatment intensity that is too low leads to minor, insufficient, effects. Too strong intensities lead to one Melting of the surfaces, the functional groups submerge inwards and are therefore inaccessible.
• the high temperatures are also disadvantageous and evaluate the necessary safety precautions.
• the applicable safety regulations for example, do not allow pulsed operation of a flame pretreatment system to. It is known that the choice of burner gas is only certain reactive species (ions and radicals) and that the cost of Flame treatment are significantly higher than with corona treatment.
• the main disadvantage of the corona treatment the localized micro-discharges (Filaments) can be avoided by using a low pressure plasma become. These mostly “cold" plasmas are by means of equal, alternating or High frequency current or generated by microwaves. With only low thermal Loads on the - usually sensitive - material to be treated become high-energy and chemically active particles are provided. These bring about a targeted chemical reaction with the material surface since the processes in the gas phase low pressure in a particularly effective manner and the discharge as represents a homogeneous space discharge cloud. With microwave excitations in the Giga-Hz range can fill entire reactor vessels with plasma discharge. in the Compared to wet chemical processes are extremely small amounts of processing agents necessary.
• DE-A-195 32 412 describes a device for pretreating surfaces Described with the help of a plasma jet.
• a highly reactive plasma jet is achieved, which has approximately the shape and dimensions has a candle flame and therefore also the treatment of profile parts permitted with a relatively deep relief. Due to the high reactivity of the A very short pretreatment is sufficient for plasma jets so that the workpiece are guided past the plasma jet at a correspondingly high speed can.
• a battery consisting of several staggered plasma nozzles been. In this case, however, the equipment is very expensive required. Since the nozzles partially overlap, it can be during treatment sheet-like materials also to strip-like treatment patterns come.
• DE-A-298 05 999 U1 describes a device for the plasma treatment of surfaces described, which is characterized by a rotary head that at least an eccentrically arranged plasma nozzle for generating a parallel to the Axis of rotation directed plasma beam carries. If the workpiece is relative to that is rotated at high speed rotating head, sweeps Plasma jet is a strip-like surface zone of the workpiece, the width of which the diameter of the circle described by the plasma nozzle when rotating corresponds. In this way it is possible with a comparatively small apparatus A relatively large surface can be rationally pretreated. Yet the surface dimensions do not correspond to those as usual when processing film materials on an industrial scale.
• the task was to develop a method that Plastic and metal foils activated homogeneously and their surface tension increased so that subsequent finishing steps, such as printing, Coating, painting, gluing, etc. without wetting problems and with good ones Have adhesive properties carried out.
• the aim was to offer a process using low pressure plasmas (Batch operation, costs), corona (filament-shaped discharge, reverse side treatment, electrostatic charging, etc.) and plasma nozzles (strip-shaped Surface treatment) to avoid given disadvantages.
• this is achieved by a method which is carried out by an indirect method Plasmatron generated atmospheric plasma on the moving over pairs of rollers sheet-like metallic material with a thickness of less than 100 ⁇ m or sheet-like polymeric material can act.
• the method according to the invention can e.g. performed with an indirect plasmatron as described in EP-A-851 720 (incorporated by referenc):
• the burner is characterized by two coaxially spaced apart Electrodes.
• a direct current arc burns between these, through an cascaded arrangement of freely adjustable length is wall stabilized. By blowing it on transversely to the arch axis, can be a band-shaped, laterally flowing Exit the plasma jet.
• This burner also called plasma broad-beam burner, is also characterized in that a magnetic field exerts a force on the arc that is exerted by the flow of the plasma gas on the arc Counteracts force.
• the torch can also use various types of plasma gases be fed.
• This method is particularly characterized in that an indirect Plasmatron with an elongated plasma chamber, which is cascaded A plurality of neutrodes electrically isolated from one another, the for Generation of the plasma light gas required electrodes coaxial to the longitudinal axis the plasma chamber are arranged and the plasma jet outlet opening in parallel runs to the longitudinal axis of the plasma chamber is used.
• At least one neutrode with a permanent magnet pair to influence the shape and position of the plasma arc. Due to the number, placement and field strength of the magnets used, you can Operating parameters such as gas volume and gas speed be taken.
• At least individual neutrodes with a possibility, e.g. one Channel for supplying a gas into the plasma chamber can be provided.
• this plasma gas can be supplied to the arc in a particularly targeted and homogeneous manner become.
• the method for surface activation described according to the invention can be both after a film production and before further processing, i.e. perform before printing, laminating, coating, etc. of foils.
• the thickness of the polymeric film materials is essentially irrelevant and moves in the thickness range of 0.5 ⁇ m and 2 cm, preferably in the range between 10 and 200 ⁇ m.
• the method according to the invention is particularly characterized in that the Surface activation of the sheet-like material both over the entire surface as well can be carried out over part of the area.
• the method for surface activation described according to the invention can be used on polymeric materials, but also for the treatment of metallic substrates, but in particular on plastic and metal foils.
• the method according to the invention can also be applied to polymeric sheet-like materials which are optionally vapor-coated with metal, metal oxides or SiO X.
• plastic films in particular understood those made of a thermoplastic material, in particular Polyolefins such as polyethylene (PE) or polypropylene (PP), made of polyester such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT) or liquid crystal Polyesters (LCP), from polyamides such as nylon 6,6; 4.6; 6; 6.10; 11; 12; made of polyvinyl chloride (PVC), made of polyvinyl dichloride (PVDC), made of polycarbonate (PC) Polyvinyl alcohol (PVOH), made of polyvinyl vinyl alcohol (EVOH), made of polyacrylonitrile (PAN), made of polyacrylic butadiene styrene (ABS), made of polystyrene acrylonitrile (SAN) Polyacrylic ester styrene acrylonitrile (ASA), made of polystyrene (PS), made of polyacrylates, such as Poly methyl methacrylate (PMMA), polyethylene terephthal
• Plastic films are also understood to mean those which consist of a thermoplastic material and with a metal of the 3rd main group or the 1st or 2nd subgroup or with SiO x or a metal oxide of the 2nd or 3rd main group or the 1st or 2nd subgroup are steamed.
• Metal foils are understood to be foils made of aluminum, copper, gold, Silver, iron (steel) or alloys of the metals mentioned.
• the activation of the surface leads to an increase in the surface tension. This ensures complete wetting with polar liquids such as Allows alcohol or water. Activation occurs when atoms or molecular fragments - excited by the plasma - with surface molecules react and as a result are built into the surface. Since this is mostly fragments containing oxygen or nitrogen also speak of surface oxidation.
• the plasma gas used in the method according to the invention is included characterized in that it consists of mixtures of reactive and inert Gases.
• the high energy in the arc leads to excitation, Ionization, fragmentation or radical formation of the reactive gas. Due to the The direction of flow of the plasma gas becomes the active species from the burner chamber carried out and can specifically interact with the surface of Plastic and metal foils are brought.
• the oxidizing process gas can be used in concentrations from 0 to 100%, preferably between 5 and 95%.
• Oxygen-containing gases and / or aerosols such as oxygen (O 2 ), carbon dioxide (CO 2 ), carbon monoxide (CO), ozone (O 3 ), hydrogen peroxide gas (H 2 O 2 ), water vapor (H 2 O.) are preferably used as oxidizing plasma gases ), evaporated methanol (CH 3 OH), nitrogen-containing gases such as nitrous gases (NO x ), nitrous oxide (N 2 O), nitrogen (N 2 ), ammonia (NH 3 ), hydrazine (H 2 N 4 ), sulfur-containing gases such as Sulfur dioxide (SO 2 ), sulfur trioxide (SO 3 ), fluorine-containing gases such as terafluorocarbon (CF 4 ), sulfur hexafluoride (SF 6 ), xenon difluoride (XEF 2 ), nitrogen trifluoride (NF 3 ), boron trifluoride (BF 3 ), silicon tetrafluoride (SiF 4 ) , Hydrogen (H 2
• the active and the inert gas are preferably mixed and in a preliminary stage then introduced into the zone of the arc discharge.
• Such plasmas used in the method according to the invention are characterized in that that their temperatures in the area of the arch at several 10,000 Kelvin lie. As the escaping plasma gas still has temperatures in the range of 1000 to 2000 Kelvin is sufficient cooling of the temperature sensitive polymeric materials necessary. This can generally be done by an effectively working cooling roller.
• the contact time of plasma gas and foil material is very important. Preferably this should be reduced to a minimum so that a thermal No damage to the materials. A minimal contact time is always through reached an increased web speed.
• the web speeds of the foils is usually higher than 1 m per minute, it is preferably between 20 and 600 m per minute.
• the plastic and metal foils in very little Pass the distance past the burner opening (nozzle). This is preferably done at a distance of 0 to 40 mm, particularly preferably at a distance of 1 to 15 mm.
• each neutrode of the plasma torch has an outlet opening for the plasma gas, this can target the arc and be fed homogeneously.
• the laterally flowing, band-shaped plasma free jet therefore leads to a particularly homogeneous processing of the surface.
• the relevant properties of the following film samples were as follows measured.
• the thermal damage to the film sections was visual or by Microscopic examinations assessed.
• the determination of the surface tension was carried out with commercially available test inks from Arcotec mechanicalntechnik GmbH according to DIN 53364 or ASTM D 2587.
• the specification of the surface tension was done in mN / m.
• the measurements were carried out immediately after treatment. The measurement errors are ⁇ 2 mN / m.
• PE 1 Single-layer, 50 ⁇ thick, one-sided corona-treated, transparent blown film made of an ethylene-butene copolymer (LLDPE, ⁇ 10% butene) with a density of 0.935 g / cm 3 and a melt flow index (MFI) of 0.5 g / 10 min (DIN ISO 1133 Condition D).
• LLDPE ethylene-butene copolymer
• MFI melt flow index
• PE 2 Single-layer, 50 ⁇ thick, one-sided corona-pretreated, transparent blown film made of an ethylene-vinyl acetate copolymer (3.5% vinyl acetate) with approx. 600 ppm lubricant (erucic acid amide (ESA)) and approx. 1000 ppm antiblocking agent (SiO 2 ), with a density of 0.93 g / cm 3 and a melt flow index (MFI) of 2 g / 10 min (DIN ISO 1133 Condition D).
• ESA ppm lubricant
• SiO 2 ppm antiblocking agent
• BOPP 1 Single-layer, 20 ⁇ thick, one-sided corona-pretreated, transparent, biaxially oriented film made of polypropylene with approx. 80 ppm antiblocking agent (SiO 2 ), with a density of 0.91 g / cm 3 and a melt flow index (MFI) of 3 g / 10 min at 230 ° C.
• SiO 2 antiblocking agent
• BOPP 2 Coextruded, three-layer, 20 ⁇ thick, one-sided corona-pretreated, transparent, biaxially oriented film made of polypropylene with approx. 2500 ppm antiblocking agent (SiO 2 ) in the outer layers), with a density of 0.91 g / cm 3 and a melt flow index (MFI) of 3 g / 10 min at 230 ° C.
• SiO 2 ppm antiblocking agent
• MFI melt flow index
• PET Commercial, single-layer, 12 ⁇ thick, one-sided corona-pretreated, biaxially oriented film made of polyethylene terephthalate.
• PA Commercial, single-layer, 15 ⁇ thick, one-sided corona-treated, biaxially oriented film made of nylon 6.
• PE 1 No. 4 to 7, Table 1

Landscapes

• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• Treatments Of Macromolecular Shaped Articles (AREA)
• Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)
• Physical Or Chemical Processes And Apparatus (AREA)
• Physical Vapour Deposition (AREA)
• Replacement Of Web Rolls (AREA)
• Undergarments, Swaddling Clothes, Handkerchiefs Or Underwear Materials (AREA)
• Plasma Technology (AREA)
• Shaping Of Tube Ends By Bending Or Straightening (AREA)
• ing And Chemical Polishing (AREA)
• Application Of Or Painting With Fluid Materials (AREA)

Applications Claiming Priority (2)

Publications (3)

Family

ID=7633970

Family Applications (1)

Country Status (11)

Cited By (1)

Families Citing this family (26)

Family Cites Families (12)

• 2000
  • 2000-03-08 DE DE10011275A patent/DE10011275A1/de not_active Withdrawn
• 2001
  • 2001-02-23 DE DE50110424T patent/DE50110424D1/de not_active Expired - Fee Related
  • 2001-02-23 EP EP01103654A patent/EP1132148B1/fr not_active Expired - Lifetime
  • 2001-02-23 AT AT01103654T patent/ATE332759T1/de not_active IP Right Cessation
  • 2001-02-26 MX MXPA01002047A patent/MXPA01002047A/es not_active Application Discontinuation
  • 2001-03-01 JP JP2001056865A patent/JP2001316855A/ja active Pending
  • 2001-03-06 CA CA002339674A patent/CA2339674A1/fr not_active Abandoned
  • 2001-03-06 US US09/800,365 patent/US6419995B1/en not_active Expired - Fee Related
  • 2001-03-06 PL PL01346291A patent/PL346291A1/xx not_active Application Discontinuation
  • 2001-03-07 BR BR0100923-0A patent/BR0100923A/pt not_active Application Discontinuation
  • 2001-03-07 RU RU2001106185/12A patent/RU2001106185A/ru not_active Application Discontinuation
  • 2001-03-07 NO NO20011152A patent/NO20011152L/no unknown

Also Published As

Similar Documents

Legal Events