Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/0081—Composite particulate pigments or fillers, i.e. containing at least two solid phases, except those consisting of coated particles of one compound
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D163/00—Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins
  • C09D163/04—Epoxynovolacs
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/08—Anti-corrosive paints
  • C09D5/082—Anti-corrosive paints characterised by the anti-corrosive pigment
  • C09D5/084—Inorganic compounds
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/80—Particles consisting of a mixture of two or more inorganic phases

Definitions

• str ⁇ -chromate-containing primers are of great importance in the manufacture of coatings for protecting metals, in particular pretreated aluminum alloys, in the aircraft industry.
• the best coating Systems for commercial aircraft have been made of a chemical conversion layer for a long time, namely a chromate, phosphate protective layer, which is created on Al surfaces by dipping, wiping, spraying or rolling as a corrosion protection and e.g. is known under the name Alodine 1200, or an acid wash primer, then an epoxyamine or polyamide anti-corrosion coating or a polyurethane (PUR) anti-corrosion coating with a high-gloss aliphatic PUR top coating. Piliform corrosion is prevented by using strontium chromate in the corrosion protection coating.
• PUR polyurethane
• Filiform corrosion is only observed on reserved substrates such as Fe, zn, Mg, steel, Ni, Cr and especially Al.
• a (star-shaped) loss of adhesion occurs between the chemically pretreated substrate and the coating from a damaged point in the paint film - preferably at atmospheric humidity of 65 - 95% and temperatures of approx. 30 ° C, which leads to the coating flaking off.
• a group of anti-corrosion pigments is also known from DE-PS 74 77 80, with inactive ones
• Fillers a compound mixture is deposited, which contains as a cation at least two of the metals calcium, strontium, barium, magnesium, zinc and as an anion chromate ion and at least one anion of carbonic, phosphoric, silica, hydrogen fluoride or boric acid. This means that a chromate is always present, and the best results are also achieved with strontium chromate.
• strontium chromate is one of the anti-corrosion pigments that, like zinc chromate, due to its carcinogenic Effects are physiologically questionable and should not be used if possible.
• Zinc phosphate and modified zinc phosphates have been tried as replacements, as shown in EU-A No. 0054266 and 0054267 and which are increasingly being used instead of zinc chromate for environmental reasons. However, these zinc phosphates do not change the filiform corrosion. Strontium hydrogen phosphates have also been studied, but these did not give the protective effect that can be seen with strontium chromate.
• EU-PS 0011223 shows a corrosion-inhibiting pigment and a phosphate-based paint, consisting of a mixture of 3 to 97% by weight of MgHPO 4 .3H 2 O, the remainder CaHPO 4 .2H 2 O.
• the pigment is particularly suitable for protecting Iron and iron alloys and can be applied as a paint or paste. Up to 95% by weight of the pigment can be exchanged for pigment extenders, for example barytes, talc, alkaline earth carbonates or wollastonite, and the pigment should be present in the dried protective layer in a pigment volume concentration of 10 to 60% by volume.
• Calcium hydrogen phosphate is not very suitable for aluminum or mixed substrates that are not exclusively made of iron and iron alloys.
• Strontium chromate are comparable. It has now been found that alkaline earth metal phosphates containing carbonate, in particular magnesium and strontium hydrogen phosphates, have better resistance to filiform corrosion than other metal phosphates, in particular also as magnesium hydrogen phosphate and strontium hydrogen phosphate without
• Carbonate component of the same alkaline earth metal Carbonate component of the same alkaline earth metal.
• the complex effect of these carbonate-containing alkaline earth phosphates is enhanced by the addition of fluorosilicates and / or
• At least 40 mol% of alkaline earth metal carbonate are required in the complex in order to provide a sufficient corrosion protection effect, even better are 50 mol% of alkaline earth metal carbonate, the remainder being alkaline earth metal hydrogen phosphate.
• a carbonate content of 80% should not be exceeded.
• fluorosilicates or fluoroborates and / or alkali or alkaline earth fluorides are relatively small and amount to about 0.05 to 3%, in particular 0.1 to 1%, with amounts of 0.1 to 0.5% often being very good
• Mol ratio of 2: 1 creates magnesium hydrogen phosphate a carbonate content of 50 mol%.
• the reaction can be carried out at temperatures between room temperature and the boiling point of the mixture, but is preferably carried out in an amount of a few kilos at temperatures from 30 to 50 ° C. for a period of 30 minutes, the time period, however, also the temperature from the amount converted depend. With a production batch of approx. 5 t, for example, the temperature rises to approx. 90 ° C due to the heat of reaction and the reaction takes approx. 3 h. The reaction time and reaction temperature are therefore longer and higher, the larger the amount used. The temperature increase also has the beneficial effect that the reaction time can be kept within reasonable limits.
• the precipitated pigments are filtered off in a customary manner, dried at 105 ° C. and ground.
• pigment 1 to 5 were compared to strontium chromate, zinc phosphate, magnesium hydrogen phosphate, strontium hydrogen phosphate in accordance with the following table in paint coating compositions which are customary for aircraft coating, by using them as a conventional 2-component coating on the basis Epoxy polyamide for aircraft was applied to aluminum sheets and then tested.
• the corrosion protection pigments mentioned were tested in comparison with strontium chromate and zinc phosphate in basic coatings in the coating structure on aluminum substrates.
• Substrate AL 2024CASTM D 1733-65) QQ-A-250/4, T 3 temper
• Base coating based on epoxy-polyamide resin (for formulations, see Tab. 2) dry film thickness 20 ⁇ m
• Top coating based on polyurethane resin
• Dry layer thickness 45 ⁇ m.
• the most important criterion for the assessment of the new corrosion protection pigments is the examination of the film shape resistance. The evaluation is carried out by measuring the average infiltration in mm at the cut.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Wood Science & Technology (AREA)
• Inorganic Chemistry (AREA)
• Composite Materials (AREA)
• Paints Or Removers (AREA)
• Pigments, Carbon Blacks, Or Wood Stains (AREA)

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• 1987
  • 1987-09-21 DE DE19873731737 patent/DE3731737A1/de active Granted
• 1988
  • 1988-09-21 US US07/734,089 patent/US5126074A/en not_active Expired - Fee Related
  • 1988-09-21 WO PCT/EP1988/000855 patent/WO1989002454A1/de not_active Ceased
  • 1988-09-21 JP JP63508029A patent/JPH0660292B2/ja not_active Expired - Lifetime
  • 1988-09-21 AU AU25334/88A patent/AU616698B2/en not_active Ceased
  • 1988-09-21 ES ES88115461T patent/ES2024605B3/es not_active Expired - Lifetime
  • 1988-09-21 EP EP88115461A patent/EP0308884B1/de not_active Expired - Lifetime
  • 1988-09-21 DE DE8888115461T patent/DE3863521D1/de not_active Expired - Lifetime

Patent Citations (2)

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