WO2022018751A1 - Revêtement protecteur à tolérance de surface et sa préparation - Google Patents

Revêtement protecteur à tolérance de surface et sa préparation Download PDF

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Publication number
WO2022018751A1
WO2022018751A1 PCT/IN2021/050694 IN2021050694W WO2022018751A1 WO 2022018751 A1 WO2022018751 A1 WO 2022018751A1 IN 2021050694 W IN2021050694 W IN 2021050694W WO 2022018751 A1 WO2022018751 A1 WO 2022018751A1
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WIPO (PCT)
Prior art keywords
composition
weight
coating
component
alkyd resin
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Ceased
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PCT/IN2021/050694
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English (en)
Inventor
Dhrubo Bhattacharya
Manish Bihani
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Individual
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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F216/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal or ketal radical
    • C08F216/38—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal or ketal radical by an acetal or ketal radical
    • 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
    • C09D129/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal, or ketal radical; Coating compositions based on hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Coating compositions based on derivatives of such polymers
    • C09D129/14—Homopolymers or copolymers of acetals or ketals obtained by polymerisation of unsaturated acetals or ketals or by after-treatment of polymers of unsaturated alcohols
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/32—Phosphorus-containing compounds
    • C08K2003/329—Phosphorus containing acids
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2205/00—Polymer mixtures characterised by other features
    • C08L2205/03—Polymer mixtures characterised by other features containing three or more polymers in a blend

Definitions

  • the present invention relates to a surface tolerant protective coating composition and preparation thereof. More particularly this invention pertains to a surface tolerant, self priming, air drying, cost effective protective coating composition for ferrous and non-ferrous metal substrates based on a vinyl terpolymer of polyvinyl formal, polyvinyl alcohol and polyvinyl acetate, an alkyd resin, and alkoxylated amino resins and also narrates a procedure for arriving at said protective coating which is user friendly, easy to apply on any type of metal surface and does not pose any environmental hazard.
  • the coating is air-drying and requires no major surface preparation such as sand/ shot/ grit blasting, when applied on new as well as old corroded steel/ metalized steel substrates.
  • the coating withstands sustained exposure to a wide range of temperature (-50°C to 150°C) and is fire retardant.
  • Self priming airdrying coatings have been developed for metal structures (U.S. Patent nos.5539032, 5427821, 5403880, 5236983, 5491185, 5202367, 5130361, and 5274021), but such formulations are not applicable on hot rolled steel with mill scale or pre-rusted steel.
  • Polysiloxane based elastomeric self priming air-drying coating has been disclosed in U.S. Patent Application no.US2011308424Al. This coating exhibits good chemical resistance and water repellency however no data has been presented on creep corrosion propagation under continuous or cyclic exposure to salt fog. Moreover, no data has been presented on oxidized steel/ metalized steel substrates.
  • the present invention addresses a pressing need for self priming air-drying protective coating devoid of toxic corrosion inhibiting agents such as lead or chromates, and ingredients containing halogens and isocyanates.
  • the said protective coat can perform on nominally prepared oxidized steel surfaces of fresh as well as pre-rusted existing structures, for cost effective, environment friendly and long-term corrosion protection.
  • the subject application incorporates some information/ data given in an earlier Patent Application no.l575/KOL/2008 which were arrived at, by one of the present applicants in the capacity of sole inventor, the said Patent Application having subsequently been withdrawn. New features and preparative procedures disclosed in the subject specification are unique and the novel coating composition has surprisingly been found to ensure dramatic reduction in life-cycle cost of structures protected therewith.
  • the principal object of this invention is to provide a surface tolerant protective coating which is long lasting, affords stability to structures coated therewith, does not necessitate repeated application at repeated intervals and ensures considerable reduction in life-cycle cost of metal substrates protected therewith.
  • a further object of this invention is to evolve a procedure to arrive at a surface tolerant protective coating composition, the application of which requires no sophisticated machinery and can be carried out under ambient conditions without being energy intensive and without damaging the environment.
  • a still further object of this invention is to maximize solids maintaining the stability of the of the subject liquid coating composition and simultaneously achieve quickest possible ambient cure using non-toxic ingredients.
  • a linear vinyl terpolymer with randomly distributed acetyl, formal, and hydroxyl groups can be incorporated with a short oil alkyd resin and a dryer therefor, alkoxylated amino resins, ortho-phosphoric acid and an acid catalyst like p-toluene sulphonic acid.
  • the composition may also incorporate extenders like mica, zinc phosphate, talc, micro-fined silica and pigment like red oxide, resulting in an air-drying coating of dry film thickness varying between 50-150 micrometers for long lasting protection of steel, metalized steel and ferrous alloys under hostile atmosphere.
  • Such coating applied on clean as well as oxidized metal substrates has been found to be quick curing, and creates a passive coating-metal interface, provides an excellent balance of thermo-mechanical properties and effective resistance to deleterious chemicals. Only loose scale, moisture, grease, residual paint and such other surface contaminants need to be removed from newly laid or existing structures/ substrates. Such coating functions equally on conventionally cleaned steel and metalized steel.
  • the essential constituents of the surface tolerant protective coating may be laid down as under, computed on the basis of 100% solid state by weight, and listing an optimal range of each of the constituents per part of the vinyl terpolymer:
  • alkyd co-resin In formulating the surface coating composition of this invention, choice of alkyd co-resin has been found to play an important role.
  • a solvent blend comprising 45-50 parts of n-butanol and 50-55 parts of toluene provides best air-drying properties.
  • suitable metallic dryer for the alkyd resin such as cobalt/ manganese/ zinc naphthenate or octoate, used singly or in combination, acid catalysts such as p-toluene sulfonic acid and o-phosphoric acid, and a combination of alkoxylated amino resins with alkyl group containing 1 to 4 carbon atoms provide accelerated cure in ambient conditions.
  • the coating may be pigmented with red oxide and produced as a two component system to be mixed prior to application. The pot life achievable is 8 hours at 30C.
  • the present invention relates to a surface tolerant, self-priming, air drying coating composition, for providing protection to ferrous and non-ferrous metal substrates, characterized in that the said composition comprises in combination a) a Vinyl terpolymer of weight average molecular weight between 20000 and 50000Daltons, constituted of randomly distributed acetyl, hydroxyl, and formal groups along the vinyl backbone with polyvinyl acetate, polyvinyl alcohol, and polyvinyl formal content by weight of 9-15% ; 6-15% ; and 70-84% respectively; b) a short oil alkyd resin of oil length approximately 40 and hydroxyl number varying between 90 and 120; c) metal dryer(s) for the alkyd resin; d) alkoxy amino resins used singly or in combination with 1-4 carbon atoms in the alkyl group; e) ortho-phosphoric acid; f) one or more acids additionally used as co-catalysts to accelerate ambient cure; g) a mix of toluen
  • This invention also pertains to preparation of the above composition which is formulated as a two component system
  • a top coat of acrylic or silicone paint may be applied.
  • the present invention may be summarized as self priming air-drying (chromate free) corrosion resistant coating composition
  • Preferred components used in the composition of this invention are a) dryer - cobalt naphthenate or octoate; b) acid catalyst - para-toluene sulphonic acid; and c) number of carbon atoms in the alkyl part of alkoxylated amino resins varying between land 4.
  • This invention also includes within its scope the procedure for arriving at the subject protective coating composition which can be briefly outlined as under:
  • a linear vinyl terpolymer with randomly distributed pendant groups of hydroxyl, acetyl and formal was selected wherein weight percentage of polyvinyl alcohol, polyvinyl acetate and polyvinyl formal in the terpolymer could vary from 6%-15%, 9%-15%, and 70-84%, respectively, and more preferably 6% - 7.5%, 10% - 13%, and 80- 83%, respectively.
  • the weight average molecular weight could vary between 20000 and 50000 Daltons, preferably between 30000 and 40000 Daltons.
  • This polymer was used in combination with a short oil alkyd resin of oil length 40 approximately and a hydroxyl number between 90 and 120, preferably between 100 and 110, with solids ranging from 70-80%, the balance being xylene.
  • Such an alkyd may be prepared by monoglyceride process, from linseed oil, glycerol and isophthalic acid with a catalyst like lithium carbonate for esterification and an aromatic solvent like xylene/ toluene.
  • the alkoxylated amino resins preferably had 1 to 4 carbon atoms in the alkyl group and preferably were a combination of a partially iso- butylated urea formaldehyde resin, containing 60% solids in a mix of xylene and iso-butanol, and a methylated melamine formaldehyde resin containing more than 97% solids.
  • the terpolymer was dissolved in the solvent mix to obtain a concentrated solution which was added to a mill base containing the alkyd, pigment and extenders.
  • Ortho-phosphoric acid and p-toluene sulfonic acid were added with the requisite amount of solvent blend required to achieve a sprayable consistency.
  • the other component comprised a blend of the alkoxylated amino resins in the solvent mix in proportions illustrated below.
  • the two components upon mixing together prior to application was found to be stable for 8 hours at 30°C.
  • the product was formulated with a solid content of a minimum of 45% by weight for the mixed composition.
  • a dry film thickness of 100 micrometers or more of the mixed coating is recommended for hot rolled/ cold rolled steel and a minimum of 50 micrometers for galvanized steel.
  • Complete ambient cure required about 10 days depending on weather conditions. This was found to be equivalent to a forced cure of one hour at 70°C.
  • the dry coating could also be top coated, if required with top coats such as acrylic or silicone paints for improved chemical resistance and/ or aggressive weather conditions.
  • EXAMPLE 2 A specific red pigmented composition was prepared from the following ingredients in the indicated weight proportions:
  • component 1 was mixed with 8 parts of component 2 to obtain the final coating composition which contained 45% solids by weight.
  • the individual components are stable for one year at 30°C.
  • the viscosity of the final mixed composition was found to be 45 ⁇ 10 seconds measured by Ford Cup B4 at 30°C, and the composition was stable and usable for at least 8 hours at 30°C. Due to low viscosity of the mixed composition the solids level of this composition may be increased up to 50% by weight.
  • Hot rolled steel comprising a) fresh with mill scale, and b) sand blasted and cold rolled steel panels were included in the investigation.
  • Cold rolled steel panels were cleaned with emery paper and washed with xylene to remove grit, oil and moisture.
  • Black hot rolled steel panels were washed with xylene and used without any mechanical cleaning to remove mill scale.
  • Sand blasted hot rolled steel panels were washed with xylene to remove all adhering particles. Coating was applied by spray on all the panels.
  • the DFT of coating on cold rolled steel panels used for all tests except salt fog corrosion test was approximately 100 micrometers while that for salt fog corrosion test (ASTM B117) was approximately 150 micrometers.
  • DFT of coating on hot rolled steel panels subjected to all tests was approximately 120 micrometers. All panels were force dried at 70°C for one hour.
  • TESTS AND RESULTS a) Drying Time, maximum i) Tack free: 4 hours at 30°C ii) hard dry: 8 hours at 30°C iii) full cure: 10 days at 30°C b) Adhesion: All coated panels exhibited excellent adhesion passing ASTM D3359, cross hatch with classification 5 A, and 2 mm grid with classification 5B. c) Hardness: Metal scratch hardness wherein a sharp steel needle loaded with a specified weight is scratched on the coated surface and the minimum weight required to expose the metal underneath the coating is recorded as scratch hardness. All types of coated panels exhibited scratch hardness of 4Kg minimum.
  • Electrochemical impedance spectroscopy This test was done only on the coated hot rolled steel panels which were top coated with an air-drying acrylic paint applied to a DFT of 50 micrometers approximately. Tests were designed to simulate marine exposure. No detectable change in polarization resistance was observed after 4350 hours of continuous exposure to salt solution containing 3.5% sodium chloride, and the value was maintained in the range of 1 to 2 xl0 10 ohm.cm 2 . At the conclusion of the test coating adherence was maintained.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Wood Science & Technology (AREA)
  • Paints Or Removers (AREA)

Abstract

Description d'un revêtement anticorrosion, séchant à l'air, à tolérance de surface et à deux composants, détaillant sa composition, sa préparation et son procédé d'application. Ce revêtement présente de multiples caractéristiques recherchées telles que la résistance thermique et l'intumescence, l'absence d'éléments toxiques dans sa composition, une remarquable résistance aux rayures et une adhérence exceptionnelle à des substrats ferreux et non ferreux préparés selon les modalités en vigueur, ce qui permet d'éviter l'étape dangereuse du sablage en préalable à son application. Une grande protection contre la corrosion est obtenue par application de ce revêtement sur de l'acier pré-rouillé et de l'acier laminé à chaud noir recouvert de calamine. La composition de revêtement comprend un terpolymère vinylique contenant des groupes acétyle, hydroxyle et formaldéhyde, une résine alkyde à acides gras à chaîne courte, des résines alcoxyaminées, des catalyseurs à base d'acide o-phosphorique et p-toluène sulfonique, des allongeurs de chaîne et un pigment, dans un mélange de solvants organiques tels que le toluène et le n-butanol. Les divers composants sont stables pendant une durée pouvant aller jusqu'à un an tandis que la composition mélangée présente une durée de vie en pot d'au moins 8 heures en conditions ambiantes.
PCT/IN2021/050694 2020-07-24 2021-07-18 Revêtement protecteur à tolérance de surface et sa préparation Ceased WO2022018751A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IN202031031663 2020-07-24
IN202031031663 2020-07-24

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WO2022018751A1 true WO2022018751A1 (fr) 2022-01-27

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1499690A1 (fr) * 2002-04-30 2005-01-26 Rotomac Electricals PVT. LTD Composition de revetement d'appret resistant a la corrosion, sans chromate et procede
US7205353B2 (en) * 2002-12-27 2007-04-17 Rotomac Electricals Pvt. Ltd. Self-priming coil coating composition and method
IN2008KO01575A (fr) * 2008-09-11 2010-03-19

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1499690A1 (fr) * 2002-04-30 2005-01-26 Rotomac Electricals PVT. LTD Composition de revetement d'appret resistant a la corrosion, sans chromate et procede
US7205353B2 (en) * 2002-12-27 2007-04-17 Rotomac Electricals Pvt. Ltd. Self-priming coil coating composition and method
IN2008KO01575A (fr) * 2008-09-11 2010-03-19

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