Petr Kalenda

A study of the effects of pigments and fillers on the properties of anticorrosive paints

Purpose – To investigate the properties of coatings containing various types of fillers from the point of view of their physical‐mechanical properties and anticorrosive properties.Design/methodology/approach – Research used fillers of different types varying in morphology and/or chemical composition; these were then compared with selected pigments and zinc phosphate, an anticorrosive pigment. The following parameters were observed for all of the fillers and pigments: oil absorption, CPVC value, density, extract pH, specific surface, particle size, and water‐soluble substances. The morphology of particles was observed by means of an electron‐scanning microscope. The coatings of these fillers and pigments were formulated on an epoxy resin binder basis cured with a polyamine hardener. The coatings prepared were subjected to the measurement of physical‐mechanical properties such as hardness and deepening resistance, flex resistance, adhesion to steel, and the gloss of the coatings. The coatings containing the...

Properties of anticorrosion pigments depending on their chemical composition and PVC value

Purpose – To identify the dependence of the anticorrosion efficiency of chemically varying pigments on their concentration in steel protecting paints.Design/methodology/approach – Anticorrosion pigments from a group of nontoxic substances were chosen and compared with a chromate pigment. With all pigments, the following parameters were observed namely, oil absorption, critical pigment volume concentration value, density, extract pH, specific surface, particle size, water‐borne substances content, and the specific electrical conductivity of pigment extracts. The aqueous extracts of pigments were used to determine the corrosion loss of steel. The morphology of pigment particles was observed by means of an electron‐scanning microscope. Paints containing these pigments were formulated on the binder basis of an epoxy resin. The paints prepared were subjected to measurement of physical‐mechanical properties such as hardness and resistance in deep drawing. Paints containing anticorrosion pigments were subjected ...

Nontoxic anticorrosion pigments of the spinel type compared with condensed phosphates

The spinel-type compounds of a general formula corresponding to AB2O4 containing as A the ions Mg2+ or Zn2+ and as B the ions Fe3+ or Al3+ or combination of both the A and B given were prepared and investigated with respect to their anticorrosive activities as pigments used in organic coatings. For comparative purposes pigments known for their efficiency as metal-corrosion-inhibiting ingredients in similar formulations were used. Condensed phosphates were also evaluated as anticorrosion pigments. The results obtained shown high anticorrosion activities of the spinel-type pigments.

Improved chemical resistance of epoxy resin-based coating compositions

Abstract The chemical resistances of epoxy resin-based compositions are significantly affected by the chemical composition, shape, size and concentration of the inorganic fillers and/or pigments used. Using a microscopic method for evaluating the diffusion of aqueous acid solutions, possibilities were found of increasing the chemical resistance of coating and casting epoxy resin-based compositions.

Ferrocene and some of its derivatives used as accelerators of curing reactions in unsaturated polyester resins

Abstract The present paper gives a discussion of the accelerating effects of ferrocene and some of its derivatives (acetylferrocene, benzoylferrocene, 1,1-dibenzoylferrocene, 1,1-diacetylferrocene, 1,2-ferrocenyl-ethane, N,N-dimethylaminomethylferrocene and chloroferrocene) in hardening unsaturated polyesters. A mechanism for the formation of active radicals which are able to initiate the hardening copolymerization reaction is proposed. These radicals are the products of ferrocene (ferrocene derivative) and a dibenzoyl peroxide reaction. By a method consisting of evaluating the resistivity values, the rate constants for hardening reactions in unsaturated polyesters and the degree of hardening achieved in the resins were determined. Differences were observed in the energies of activation for the hardening reactions using various ferrocene derivatives.

Catalytic effects of transition metals in the form of the salts of organic acids in the cross linking of alkyds

Purpose – To study the drying effects of cobalt, manganous and mixed salts for their catalytic action in cross linking reactions occurring during the creation of an alkyd resin film.Design/methodology/approach – The driers of Co‐octoate, Mn‐octoate, Mn‐octoate with an active organic ligand, and mixed drier containing the salts of Mn, Ca, and Zn were employed in the cross linking reactions of alkyls. The study verified the possibility of using manganese as an active cation in catalytic curing reactions. The course of the cross‐linking of alkyds was monitored on a model system of the reactions of drier with ethyl linoleate, using FTIR spectroscopy. Reaction‐rate constants corresponding to the first phase of cross linking were obtained. The driers under scrutiny were used to identify the time of the drying of alkyd resin modified with flax oil. The final phase of the cross linking reactions was monitored by means of measurement the hardness of the created alkyd film depending on time.Findings – The driers un...

Pigments with Ti4 + −Zn2 + , Ca2 + , Sr2 + , Mg2 + ‐based on mixed metal oxides with spinel and perovskite structures for organic coatings

Purpose – The purpose of this paper is to synthesise X2TiO4 spinel‐type anticorrosion pigments and YTiO3, perovskite‐type anticorrosion pigments, where X = Zn, Mg, Ca, Sr; Y = Ca for metal protective paints.Design/methodology/approach – Anticorrosion pigments were synthesised from oxides or carbonates at high temperature. The following pigments were synthesised: TiO2 · ZnO, 2TiO2 · ZnO, TiO2 · 2ZnO, TiO2 · MgO, TiO2 · CaO, TiO2 · ZnO · MgO, and TiO2 · ZnO · SrO. The pigments obtained were characterised by means of X‐ray diffraction analysis, measurement of particle sizes and scanning electron microscopy. The anticorrosion pigments synthesised were used to produce epoxy coatings with PVC = 10 per cent for each synthesised pigment. The coatings were tested for physical‐mechanical properties and in corrosion atmospheres. The corrosion test results were compared with those of alumino zinc phosphomolybdate.Findings – A spinel or perovskite structure was found in the pigments synthesised. High anticorrosion eff...

Possibilities of affecting the chemical resistances of the coatings formed by reaction of amino resins with alkyd resins

The paper deals with the mode of film formation from urea–formaldehyde and melamine–formaldehyde resins combined with alkyd resin based on castor oil‐modified alkyd. The properties of hardened coatings (such as hardness, chemical stability, and adhesion to substrate) were followed in dependence on the ratios of reaction components. An apparatus was built for measuring the formaldehyde emissions escaping from the solid coating films. The determination was performed by the pararosaniline method. The addition of imidazolidine in a concentration up to 10 per cent can reduce the emissions of formaldehyde escaping from the solid films to a considerable amount.

Study of the resistances of organic coatings to filiform corrosion

The filiform corrosion is a special-type atmospheric corrosion, which broadens below the organic coatings and is characterized by its manifestation in the form of fibres or filaments. An important factor for broadening the filiform corrosion involves also the barrier or chemical resistance of the organic coating. The paper deals with the modes of filiform-corrosion initiation and evaluation thereof under nonpigmented organic coatings based on various binder bases. Also the possibility of retardation of the filiform corrosion by means of zinc powder and the effects of lamellar pigment on the filament shapes are studied.

Drying activity of oxovanadium(IV) 2-ethylhexanoate in solvent-borne alkyd paints

Oxovanadium(IV) 2-ethylhexanoate was established as a new primary drier for alkyd-based paints. A series of experiments has demonstrated an excellent drying activity toward solvent-borne alkyd resins of different oil length at considerably lower metal concentration than optimal for commercial cobalt(II) 2-ethylhexanoate. The behavior in real paint was simulated on formulations bearing inhibitor of autooxidation. The detailed studies of the drying process have shown that the relatively slow initial step of autooxidation reaction, when compared with cobalt compounds, is compensated for by the absence of the induction times. Furthermore, the active oxovanadium(IV) species are not consumed during the drying processes as evidenced by EPR spectroscopic measurements.