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
  • B05D1/00—Processes for applying liquids or other fluent materials
  • B05D1/62—Plasma-deposition of organic layers

Definitions

• the present invention relates to a method for coating polymeric substrates with a long-term stable, polar coating, a method for increasing the wettability or printability of polymeric substrates, such as in particular packaging films, containers and the like made of polymeric materials, and a stable, polar, polymeric Coating of a substrate, produced using the method according to the invention.
• polymeric substrates such as, in particular, flexible substrates
• the coating of polymeric substrates takes place, inter alia, in order to influence the surface quality or the appearance of the polymer, or to protect the surface both mechanically, physically and chemically. Be this to increase the adhesion to the surface or the printability, to prepare the surface for further functional coatings, to ensure protection against abrasion or damage, to reduce the permeability of certain gases or liquids to or through the surface of the substrate or to prevent, or to increase the chemical resistance of the substrate to certain chemicals.
• JP-59-15569 and PCT / AU89 / 00220 propose to coat a polymeric substrate by means of plasma polymerization of an organic compound, together with optionally a working gas and water or water vapor. Furthermore, it is proposed in WO95 / 04609 to treat or coat the surface by means of plasma polymerization of an organic compound in the presence of hydrogen peroxide.
• the coatings proposed from the prior art have poor adhesion to the substrate or are poorly wettable.
• the use of peroxide or water and oxygen is problematic because the "working gas" thus obtained is aggressive and can attack the surface of the substrate (etching). It is therefore an object of the present invention to propose a coating method for polymeric substrates which does not have the existing disadvantages.
• the process gas used for the plasma polymerization in a plasma reactor being anhydrous or steam-free and which contains at least one organic compound and an inorganic gas and / or carbon monoxide and / or carbon dioxide and / or ammonia and / or another N-containing gas.
• the organic compound is a hydrocarbon compound which is relatively low molecular weight or which has up to a maximum of eight carbon atoms, as a result of which the compound has a relatively high vapor pressure at room temperature.
• Alkanes, alkenes, alkynes (acetylene), polyenes, mono- or polyhydric alcohols, carboxylic acids, ethers, aldehydes and / or ketones are preferably used. These can be aliphatic, cycloaliphatic or aromatic hydrocarbon compounds.
• the use of water vapor as process gas in a gas discharge is anything but ideal and must be avoided. Furthermore, a water-containing layer has a lower chemical and thermal resistance, which will have a negative effect on the subsequent processing steps as well as the definition and stability of the layers.
• the plasma-polymerized layer according to the invention is water-free and so compact that, although it is hydrophilic, it absorbs almost no water during further processing. - 4 -
• the process gas or working gas used for the plasma polymerization is water-free or steam-free.
• the absence of water or water vapor at least in the process gas can also ensure in any case that the working gas or gas mixture may not contain any peroxide compounds which can form, for example, when water and oxygen are used in the plasma chamber.
• all known plasma methods such as, for example, microwave discharge, high or high-frequency discharge, are suitable for carrying out the method proposed according to the invention
• the method proposed according to the invention is also suitable for the coating of all known polymer substrates used today, for example for the production of packaging materials, such as polyethylene , Polyamide, polypropylene, PMMA, PVC, polyester such as PETP, PBTP, polyimide, polycarbonate etc. etc.
• packaging materials such as polyethylene , Polyamide, polypropylene, PMMA, PVC, polyester such as PETP, PBTP, polyimide, polycarbonate etc. etc.
• the polar layer can then serve as an adhesion promoter between these materials and further layers, such as, for example, corrosion protection layers, or enable the bonding of different materials, such as metal / polymer, etc.
• the polymer substrate mentioned is provided with a polar polymer-like coating or with a plasma layer with a high surface tension, in which coating polar groups are incorporated, such as hydroxyl, carboxyl, carbonyl groups (see FIGS. 2a and 2b) or NO x groups, as a result of which excellent adhesion for polar functional layers and / or polar materials can be achieved on the surface of this coating, which is expressed, for example, in very good printability.
• coating polar groups such as hydroxyl, carboxyl, carbonyl groups (see FIGS. 2a and 2b) or NO x groups
• coating polar groups such as hydroxyl, carboxyl, carbonyl groups (see FIGS. 2a and 2b) or NO x groups
• The, for example, flexible substrate to be coated such as, for example, a film, a hollow body or the like, is introduced into a vacuum chamber into which the working gas, consisting of the components mentioned, is introduced. It is essential, as already mentioned above, that this working gas is free of water, water vapor or moisture.
• a plasma-polymerized layer is then deposited on the surface of the material to be coated using the plasma process.
• the coating produced in this way by means of plasma polymerization generally has a layer thickness of a few nm, for example between 1 and 100, preferably 5 to 20 nm; however, it can also be a few ⁇ m.
• the layer thickness depends on the requirements as to whether scratch protection or an anti-fog effect should be achieved in addition to the printability, to which the coating achieved according to the invention can also make a contribution.
• the ratio between the inorganic gas component, such as oxygen, nitrogen, ammonia or carbon monoxide or carbon dioxide, and the organic compound also depends on the properties of the coating.
• the ratio can vary widely, depending on which components contain the gas mixture or the working gas. Table 1 shows a few examples. To- - 7 -
• noble gases such as argon, helium, etc.
• organic compounds are alkanes with a chain length of up to about eight carbon atoms, such as methane, ethane, propane, etc.
• alkenes such as ethylene, propylene, etc., are also suitable as organic compounds.
• acetylene or compounds based on acetylene such as the so-called alkynes.
• Polyenes are also suitable, i.e. Hydrocarbons with several double bonds, again with up to about eight carbon atoms.
• Alcohols such as methanol, ethanol, propanol etc. and polyhydric alcohols such as ethylene glycol are also suitable.
• Mono- or polyvalent organic acids, ethers, aldehydes and ketones are also suitable.
• the hydrocarbon compounds described can be aliphatic, cycloaliphatic or aromatic hydrocarbons, although all of the above-mentioned compounds can of course also be substituted, for example by amino groups, halogens, ammonia, etc.
• a plasma reactor is flooded with the process gas mixture until the desired process pressure is reached, for example 1.6 x 10 " 2 mbar.
• a microwave discharge (2.45 GHz) was then ignited, the process gases being supplied continuously.
• a layer with a polar fraction of 41% and a surface tension of 50 mN / m was achieved with a gas mixture of 48 sccm (standard cubic cm per minute) C0 2 , 12 sccm CH 4 and 12 sccm Ar, with a microwave power of 62 watts (sample 10 / PET).
• the substrate was a 12 ⁇ m thin PET film or a 20 ⁇ m thin polypropylene film (sample 2 / BOPP), representative of polymeric substrates.
• An increase in the process pressure up to atmospheric pressure will lead to a higher deposition rate and is currently the status of the optimization of the coatings.
• Table 1 also shows that the desired surface tension for the corresponding substrate can be achieved by varying the output and the process gas mixture. The comparison of the different gas mixtures in Table 1 shows that the gas mixture has a greater influence on the hydrophilicity than the variation of the power supplied to the plasma by 80 watts.
• Table 1 shows the coatings which were produced between July and October 1997 and for which the surface tension was measured again in January 1999.
• the area share 1 is 6.5%
• the area share 3 is 8.9%
• the share 5 is 20.1%
• the area share 7 is 64.5%.
• the total carbon content is 76.2% and that of oxygen is 23.8%.
• the ratio of carbon to oxygen is therefore 76.2: 23.8.
• the area share 1 is 15.4%, of area 3 2.6%, of area 5 20.0% and of area 7 61.9%.
• the share C (ls) is 70.0% and the share 0 (ls) 30.0%. - 10 -
• PET polyethylene terephthalate film 12 ⁇ m thick
• BOPP Biaxially oriented polypropylene 20 ⁇ m thick
• test conditions described above for example, only serve to explain the basic idea of the present invention in more detail.
• Coating any functional layer which is more polar in nature
• printing laminating (gluing - adhesion to polar adhesives) is made possible on such a polar surface for new printing media and adhesives based on the solvent water.
• doping of the coating with inorganic anions (nitrogen, fluorine, etc.) and inorganic cations (metals and metal oxides) are provided. This means that other properties, such as the electrical conductivity of the layer can be set accordingly for the product requirement.
• the working gases used for the plasma polymerization are water-free or free of water vapor or moisture.

Landscapes

• Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• Physics & Mathematics (AREA)
• Treatments Of Macromolecular Shaped Articles (AREA)
• Paints Or Removers (AREA)
• Coating Of Shaped Articles Made Of Macromolecular Substances (AREA)
• Laminated Bodies (AREA)
• Polarising Elements (AREA)
• Absorbent Articles And Supports Therefor (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Liquid Crystal Substances (AREA)
• Polymers With Sulfur, Phosphorus Or Metals In The Main Chain (AREA)
• Organic Insulating Materials (AREA)

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• 1999
  • 1999-02-05 DE DE59904532T patent/DE59904532D1/de not_active Expired - Lifetime
  • 1999-02-05 US US09/601,709 patent/US6746721B1/en not_active Expired - Fee Related
  • 1999-02-05 AU AU21472/99A patent/AU2147299A/en not_active Abandoned
  • 1999-02-05 EP EP99901558A patent/EP1051266B1/fr not_active Revoked
  • 1999-02-05 AT AT99901558T patent/ATE234165T1/de not_active IP Right Cessation
  • 1999-02-05 BR BR9907692-6A patent/BR9907692A/pt not_active Application Discontinuation
  • 1999-02-05 WO PCT/CH1999/000050 patent/WO1999039842A1/fr not_active Application Discontinuation
  • 1999-02-05 CA CA002318129A patent/CA2318129A1/fr not_active Abandoned
  • 1999-02-05 JP JP2000530320A patent/JP2002502688A/ja active Pending

Non-Patent Citations (1)

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