INSTITUTE FOR PLASTICS PROCESSING METALCHEM W TORUNIU ul' Marii Sklodowskiej Curie 55 87100 Torun PA

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INSTITUTE FOR PLASTICS PROCESSING
METALCHEM W TORUNIU ul. Marii
Sklodowskiej Curie 55 87-100 Torun
PAINT PLASTICS DEPARTMENT 44-100
Gliwice, ul. Chorzowska 50 Centrala
48(32) 231-90-41 Fax 48(32)
231-26-74 Kierownik Oddzialu 48(32)
231-21-81 e-mail main_at_iptif.com.pl
NIP 879-017-06-91 BZ WBK SA I O/Torun 151090
1506 0000 0000 5002 018
Autor STEFAN KUBICA

• Anticorrosive coating formulations containing
  nanocomponents showing bacteriostatic or biocidal
  action

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Mechanisms of surface protection with organic
coatings

• Electromechanical mechanism corrosion reactions
  are prevented either by metal passivation with
  anticorrosion pigments or by creation of strongly
  adherent, stable layers
• Barrier mechanism factors contributing to
  corrosion, present in the surrounding
  environment, have limited access to the surface
  These two mechanism operate simultaneously, and
  it is binder and pigment type that decides which
  one dominates.

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Effective anticorrosion pigments

• Chromium compounds (VI)
• Lead compounds,
• due to their toxicity eliminated from paint
  formulations
• Zinc phosphorate,
• considered non toxic for a long time, it has
  been placed on the list of dangerous substances
  recently (Directive 2004/73/EC R-50/53 very
  toxic for water organisms)) EU member states are
  obliged to implement rules of that Directive by
  the end of October 2005.
• Conclusion
• It is justified to assume that modern protective
  coatings will play their role only due to the
  excellent barrier properties and anticorrosion
  pigments or corrosion inhibitors will be excluded
  from their formulations.

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Effectiveness of protective properties of
organic coatings

• Structure of a coating influences its barrier
  properties and plays a crucial role in surface
  protection The barrier performance of a coating
  is determined by
• Chemical structure of a polymer/binder,
• Homogenous dispersion of solid phase (pigments
  and extenders),
• Affinity of a coating surface to polymer matrix
• Improving coatings structure
• lowers
• Water, electrolyte, and gas permeability
• increases
• Adhesion and scratch resistance as well as
  resistance to other mechanical damage
• New ideas
• Addition of new components eg, nanocomposites to
  improve barrier properties of coatings

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Nanocomposites in coatings

• Hybrid organic/inorganic coatings are obtained by
  addition of nanocomposites to a binder either
  with dispersion method or with a sol-gel method.
  Preparation of nanocomposite structure with
  surfactants prior to addition facilitates
  incorporation of a extender to a paint,
  increasing its effectiveness in a coating.
• Nanocomposites used in paints are, most
  often,silicas, silicates, titanium dioxides,
  barium sulfate, aluminium or cyrconium oxides,
  with paritcles sizes up to some hundred nm. They
  can be used in acrylic, poliurethane and epoxy
  binders, both water and solvent borne.

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Why nanocomposites ?

• Improvement of a barrier properties of coatings
  
• Corrosion resistance
• Mechanical properties,
• Combining properties of organic compounds
  (elasticity, low softening point) with properties
  of inorganic nanoparticles ( hardness,
  weathering resistance)
• Possibility to obtain coatings with homogeneity
  comprised between organic and inorganic parts
  that would be controlled on molecular level.

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Coatings with nanoparticles in automotive industry

• Growing demands of car users and car
  operating conditions are the main factor
  determinig type of coatings used by automotive
  industry. Increasing interest in coatings with
  nanoparticles is atributed to properties they can
  assure. Coatings used by automotive industry must
  show
• corrosion resistance
• resistance to splinter
• wet and water resistance
• scratch resistance
• resistance to acids, solvents and chemicals.

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Nanoparticles in coatings development directions

• Paints with nanoparticles fulfill all demands
  required from automotive coatings listed
  previously. As nanoparticles size is comparable
  with visible light wave length range (400-800
  nm), they disperse small amount of light and do
  not influence optical properties of a coating as
  such they can be used in transparent top coats.
• Special automotive coatings with diamond
  nanoparticles - material with the highest
  hardness among all known substances. Coatings
  with diamond nanoparticles show excellent impact
  and scratch resistance as well as resistance to
  chemicals (mainly solvents) such coatings are
  also resistant to dirt pick-up (coating with
  antiadhesive properties).
• Research has been done to utilize nanoparticles
  in steel and aluminium alloys coatings, that
  would enable exchanging controversial chromium
  coating and anticorrosive primer with strontium
  chromate.
• Organic/inorganic coatings for a aviation
  industry, obtained with sol-gel method are
  expected to exchange systems that utilize
  chromates and allow elimination of poliurethane
  coating.

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Heavy metals as factor inhibiting microorganisms
growth

• For many years heavy metals, either as inorganic
  salts or as organic compounds, have been used to
  destroy and inhibit growth of various
  microorganisms excellent antimicrobial
  effectiveness is observed for minor amounts of
  heavy metals e.g..
• Zinc organic compounds,
• Lead and mercury salts
• despite splendid antimicrobial and technological
  properties, their use is either completely banned
  or very strongly limited, due to the toxicity
  towards humans and animals
• Heavy metals with strong antimicrobial action
  but not toxic to humans and animals such as
  copper and silver can be used instead.

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Silver and copper ions as protection against
microorganisms

• Silver ions in concentrations as low as a few ppm
  assure effective protection against
  microorganisms AgNO3 (lapis infernalis) has
  proved to be effective aseptic medium in medicine
  for more then 100 years.
• Cu (II) or Ag (I) ions in concentrations 10-6
  mol/l inhibit growth of various bacteria. Cu (II)
  ions in concentration 10-3 mol/l are sufficient
  to inhibit growth of yeast and most of moulds.
  There are however species resistant to Ag or Cu
  ions e.g. Penicilinum sp. or Asp. niger can grow
  and proliferate in saturated CuSO4 solutions

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Conditions and ways of utilization of silver as
antimicrobial agent

• Controlled and effective release of silver ions
  into the surrounding environment or a product is
  a key factor determining its use as a
  antimicrobial agent.
• An example of such a controlled release is a AgCl
  on porous TiO2. Composition Ag/TiO2 shows
  effectiveness toward Escherichia coli,
  Staphylococcus aureus and Staphylococcus xylosus.

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The most up-to-date solutions in bacteriostatic
protection

• Titanium dioxide nanoparticles with silver.
• Silver complex compounds. It is noteworthy high
  activity against wide range of bacteria e.g.
  Aspergillus niger, Penicillum citrinum,
  Aspergillus terreus, Rhisopus stolonifer,
  Cladiosporium caldosporioides, Penicillium
  islandicum).
• Silver complex compounds, with silver bound with
  sulphur atom also show antimicrobial properties.
  However lower compared to other complexes.
• Gold complex compounds also possess antimicrobial
  properties.