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Article
Publication date: 1 June 2005

Nivin M. Ahmed

Kaolin (hydrated aluminum silicate) is one of few minerals that are found in nature in a relatively pure state which is abundant in many places of the world. In this…

Abstract

Purpose

Kaolin (hydrated aluminum silicate) is one of few minerals that are found in nature in a relatively pure state which is abundant in many places of the world. In this research, a simple chemical treatment using traces of ammonium molybdate was carried out to enhance the anticorrosive properties of kaolin.

Design/methodology/approach

The steps of treatment of kaolin at 1,000°C were estimated. Characterization of three different combinations of aluminum oxide with iron oxide were studied using spectroscopic methods of analysis via X‐ray diffraction (XRD), transmission and scanning electron microscopy (TEM and SEM). Also, evaluation of the prepared pigments using (oil absorption, specific gravity, water‐soluble matter, and pH) international standard testing methods were estimated. Then these prepared pigments were incorporated in anticorrosive paint formulations based on medium oil alkyd resin as a binder, the physico‐mechanical and anticorrosive properties of paint films were detected by testing them in 3.5 percent NaCl solution for 28 days.

Findings

Introduction of small amounts of ammonium molybdate in kaolin promoted its physico‐mechanical and anticorrosive properties. Although, this process of treatment is economically feasible, treated kaolin can replace expensive commercial pigments found in markets with an almost near quality to their performance.

Originality/value

Treated kaolin can be applied in many industries beside pigment manufacture, and paint formulations, it can be applied as reinforcing filler in rubber, plastics, and ceramic composites. Also it is applied in paper filling, paper coatings, and electrical insulation.

Details

Anti-Corrosion Methods and Materials, vol. 52 no. 3
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 11 January 2011

Nivin M. Ahmed and Mohamed M. Selim

Kaolin is a soft, white mineral mainly composed of coarse‐ to fine‐grained, plate‐like aluminum silicate particles. As kaolin assists with desired rheological properties…

Abstract

Purpose

Kaolin is a soft, white mineral mainly composed of coarse‐ to fine‐grained, plate‐like aluminum silicate particles. As kaolin assists with desired rheological properties that help maintain proper dispersion and provide bulk to the product, it is used as an important extender in paint manufacture. It can be used to reduce the amount of expensive pigments, such as titanium dioxide. In spite of these uses, kaolin has the disadvantage of having coarse particles and low hiding power. The purpose of this paper is to introduce a new class of pigments based on kaolin as a core and titanium dioxide as the shell.

Design/methodology/approach

In the work reported in this paper, kaolin was used as a core covered with a surface layer of titanium dioxide comprising the shell in order to combine their properties and get over kaolin's disadvantages, besides enhancing its corrosion protection properties. The pigments prepared were characterised using X‐ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Deposition of titanium dioxide on the surface of kaolin was confirmed by Energy‐dispersive X‐ray analysis (EDAX) and X‐ray fluorescence (XRF) techniques. Pigment properties were estimated according to American standard testing methods (ASTM) methods and then were incorporated in anticorrosive paint formulations based on medium oil alkyd resin. The physico‐mechanical and corrosion properties of dry paint films were determined according to ASTM methods.

Findings

The tests revealed that the concentration of titanium dioxide layer deposited on kaolin surface was inversely proportional to the anticorrosive behaviour of these pigments.

Practical implications

The pigments can be applied in other polymer composites, e.g. rubber and plastics as filler and reinforcing agent.

Originality/value

The pigments prepared are eco‐friendly that can replace other expensive pigments. These pigments can compensate for the presence of titanium dioxide in paint formulations successfully, and thus lower the costs. The main advantage of these pigments is that they combine the properties of both of their counterparts, they are of lower cost, and they also overcome the disadvantages of both its counterparts, e.g. low hiding power of kaolin, photochemical activity of titanium dioxide. Also, they can be applied in other industries other than paints, e.g. paper, rubber and plastics composites.

Details

Pigment & Resin Technology, vol. 40 no. 1
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 4 January 2013

Nivin M. Ahmed

Kaolin is a soft white mineral which has a large array of uses. It is most commonly referred to as “China clay”. Sources of this mineral can be found all over the world…

Abstract

Purpose

Kaolin is a soft white mineral which has a large array of uses. It is most commonly referred to as “China clay”. Sources of this mineral can be found all over the world, its uses are multiple and diverse. It is a mineral belonging to the group of alumino‐silicates with the chemical composition Al2Si2O5(OH)4. It is white, soft, plastic clay mainly composed of plate‐like particles. It is a unique industrial mineral, which remains chemically inert over a relatively wide pH range. The purpose of this paper is to study the difference in performances of untreated or natural kaolin, thermally treated kaolin or so‐called “calcined kaolin” and chemically treated kaolin using ammonium molybdate to convert the γ‐Al2O3 naturally found in kaolin to α‐Al2O3 which possesses one of the most known stable crystalline phases (corundum) in alkyd based anticorrosive paint formulations used for protection of steel.

Design/methodology/approach

The different kaolins were characterized using different analytical and spectro‐photometric techniques. The pigments were characterized using X‐ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Evaluation of these pigments using international standard testing methods (ASTM) was estimated. The extender pigments were then incorporated in solvent‐based paint formulations based on medium oil‐modified soya‐bean dehydrated castor oil alkyd resin. The physico‐mechanical properties of dry films and their corrosion properties using accelerated laboratory test in 3.5% NaCl for 28 days were tested.

Findings

The results of this work revealed that calcined kaolin was better in its performance in protection of steel than kaolin, while chemically treated kaolin varied in its performance according to the concentration of modifier or dopant.

Practical implications

Kaolin has a large array of uses. These pigments can be applied in other polymer composites, e.g. rubber and plastics as reinforcing agent.

Originality/value

The untreated and treated kaolins are environmentally friendly pigments which can impart high anticorrosive behaviour to paint films with concomitant cost saving.

Details

Pigment & Resin Technology, vol. 42 no. 1
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 23 March 2010

Nivin M. Ahmed and Mohamed M. Selim

The purpose of this paper is to determine a new easy route to obtain high performance and economic anticorrosive hybrid pigments based on kaolin and ferrite. The new route…

Abstract

Purpose

The purpose of this paper is to determine a new easy route to obtain high performance and economic anticorrosive hybrid pigments based on kaolin and ferrite. The new route is based on depositing a surface layer of an expensive efficient anticorrosive pigment (ferrite) on a bulk of cheap extender pigment (kaolin). The combination of these pigments can add improved properties to the new pigment different from each of its individual components. These improved properties lead to imparting new properties to paint films containing these prepared pigments.

Design/methodology/approach

The new prepared hybrid pigments contain different concentrations of deposited ferrite on kaolin surface, are determined using X‐ray fluorescence analysis to estimate the concentration of each element in the pigments. The pigments are characterised using different spectro‐photometric and analytical methods to prove the deposition of the shell layer and elucidate the structure of their particles. Then, they are incorporated in anticorrosive paint formulations, where their presence in these formulations is between 50 and 75 per cent of the total pigments in the paint formula. A model of the mechanism of protection to the metal substrate is presented.

Findings

The results show that the presence of these hybrid pigments imparts excellent corrosion protection to steel substrates, in spite of their different concentrations and loadings in the paint films.

Practical implications

These pigments can be applied in other polymer composites, e.g. rubber and plastics as filler and reinforcing agent.

Originality/value

Prepared pigments are eco‐friendly and can replace other hazardous pigments (e.g. chromates) – also it can replace original ferrite pigments. These pigments can compensate for the presence of other known pigments in markets successfully. The main advantage of these pigments is that they combine both the properties of their counter‐parts, and they are of lower cost than the original inhibitive pigment (ferrite). Also, they can be applied in other industries other than paints, e.g. paper, rubber and plastics composites.

Details

Pigment & Resin Technology, vol. 39 no. 2
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 7 September 2015

Nivin M Ahmed, Walaa M. Abd El-Gawad, Elham A. Youssef and Eglal R. Souaya

The purpose of this paper is to present the preparation of core-shell ferrites/kaolin pigments and comparing their efficiency in protecting metal substrates to original…

Abstract

Purpose

The purpose of this paper is to present the preparation of core-shell ferrites/kaolin pigments and comparing their efficiency in protecting metal substrates to original ferrites which were also prepared. Core-shell structured particles are recently gaining lots of importance due to their exciting applications in different fields; these particles are constructed from cores and shells of different chemical compositions which show ultimately distinctive properties of varied materials different from their counterparts. The new core-shell pigment is based on shell of different ferrites that comprises only 10-20 per cent of the whole pigment on kaolin (cores) which is a cheap and abundant ore that comprises 80-90 per cent of the prepared pigment. The new pigments do not only comprise two different components, but they also contain pigment and extender in the same compound; their loadings in the paint formulations ranges from 50 and 75 per cent of the whole pigment. The work showed that these eco-friendly and cheap core-shell pigments are comparable in their efficiency to that of ferrites in protecting steel substrates.

Design/methodology/approach

The different ferrites and ferrites/kaolin pigments were characterized using different analytical and spectrophotometric techniques, such as X-ray fluorescence, X-ray diffraction (XRD), scanning electron microscopy/energy-dispersive X-ray (SEM/EDAX) and transmission electron microscopy (TEM). Evaluation of these pigments was done using international standard testing methods (ASTM). After evaluation, the pigments were incorporated in solvent-based paint formulations based on medium oil-modified soya-bean dehydrated castor oil alkyd resin. The physico-mechanical properties of dry films and their corrosion properties using accelerated laboratory test in 3.5 per cent NaCl for 28 days were determined.

Findings

The results of this work revealed that ferrite/kaolin core-shell pigments were close in their performance to that of the ferrite pigments in protection of steel, and at the same time, they verified good physico-mechanical properties.

Practical implications

Treated kaolin can be applied in many industries beside pigment manufacture and paint formulations; it can be applied as reinforcing filler in rubber, plastics and ceramic composites. Also, it is applied in paper filling, paper coatings and electrical insulation.

Originality/value

Ferrite and ferrite/kaolin are environmentally friendly and can replace other hazardous pigments (e.g. chromates) with almost the same quality in their performance; also, they can be used in industries other than paints, for example paper, rubber and plastics composites.

Details

Pigment & Resin Technology, vol. 44 no. 5
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 2 March 2015

Salwa H El-Sabbagh and Nivin M. Ahmed

This paper aims to express in detail the rheological, morphological and thermal properties of unpigmented and pigmented styrene-butadiene rubber composites with new…

Abstract

Purpose

This paper aims to express in detail the rheological, morphological and thermal properties of unpigmented and pigmented styrene-butadiene rubber composites with new prepared inorganic pigment based on kaolin covered with a thin layer of calcium and magnesium oxides or mixed oxide of both together. These new pigments combine the properties of both their constituents (kaolin and metal oxides), which are a new trend in inorganic pigments called core-shell pigments. The pigments used for comparison are kaolin (K), CaO/kaolin (CaO/K), MgO/kaolin (MgO/K) and CaO.MgO/kaolin (CaO.MgO/K).

Design/methodology/approach

The different pigments were characterized using different analytical and spectrophotometric techniques, such as X-ray diffraction, scanning electron microscopy/energy dispersive X-ray and transmission electron microscopy, while rubber vulcanizates' rheological, morphological, swelling and thermal properties were examined using different standard and instrumental testing and methods.

Findings

The study revealed that there is a significant effect of the new prepared pigments on SBR properties, where the optimum pigment loading was 40 phr for CaO/kaolin, while it was 2.5 phr for MgO/kaolin. Studying the effect of different ratios of oxides on kaolin (5, 10 and 20 per cent), different loadings of these pigments ranging between 2.5 and 40 phr were done for each pigment. These modified kaolin or core-shell metal oxide/kaolin pigments imparted new and improved reinforcing properties to SBR vulcanizates.

Research limitations/implications

No research limitations were found.

Practical implications

Core-shell MgO/kaolin pigments are eco-friendly and can replace other expensive pigments that are usually used as fillers in the rubber industry with less expenses and comparable efficiency.

Originality/value

These new pigments are cheap and efficient and can be used in different fields other than rubber.

Details

Pigment & Resin Technology, vol. 44 no. 2
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 12 January 2010

Nivin M. Ahmed and Mohamed M. Selim

The purpose of this paper is to introduce a new method of pigment preparation, which is economic and highly efficient in corrosion protection properties, known as the…

Abstract

Purpose

The purpose of this paper is to introduce a new method of pigment preparation, which is economic and highly efficient in corrosion protection properties, known as the core‐shell method. According to this method, a cheap core (an extender) is covered with only a surface layer of effective pigments. Following this method of preparation, a new group of pigments is prepared in this research using the Egyptian kaolin ore as the core covered with single and mixed zinc, magnesium, and zinc‐magnesium phosphates as a shell to replace the original phosphates. These new pigments combine the properties of both its core and shell counter‐parts exhibiting improved corrosion protection properties that exceed both of kaolin and zinc phosphate individually.

Design/methodology/approach

Pigments concerned in this paper are prepared using simple chemical techniques, and then they are characterised using X‐ray diffraction, scanning electron microscopy combined with energy‐dispersive X‐ray analysis, and transmission electron microscopy. These pigments are incorporated in solvent‐based paint formulations based on medium oil alkyd resin. The physico‐mechanical properties of dry films and their corrosion properties are tested using accelerated laboratory test in 3.5 percent NaCl for 28 days, according to ASTM.

Findings

The prepared kaolin‐phosphate (core‐shell) pigments are based essentially on Egyptian kaolin ore, which is an abundant cheap ore in Egypt, and then the kaolin is covered with a surface layer of phosphates that are proved to be efficient anticorrosive pigments. These pigments are easily prepared, economically feasible and can successfully replace ordinary phosphate pigments with superior corrosion protection behaviour.

Practical implications

These pigments can be applied in other polymer composites, e.g. rubber and plastics as reinforcing agent.

Originality/value

Prepared pigments are environmentally friendly and can replace hazardous pigments (e.g. chromates) and ordinary phosphates. The main advantages of these pigments are that they combine both the properties of their core and shell counter‐parts, and they are of lower cost with similar and maybe in some cases better efficiency in corrosion protection of metals. Also, they can be applied in industries other than paints, e.g. paper, rubber and plastics composites.

Details

Pigment & Resin Technology, vol. 39 no. 1
Type: Research Article
ISSN: 0369-9420

Keywords

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Article
Publication date: 31 December 2015

Nivin M Ahmed, Walaa M. Abd El-Gawad and Eglal R. Souaya

The purpose of this study is to prepare core-shell ferrites/kaolin pigments and compare their efficiency in protecting metal substrates to original ferrites. The new…

Abstract

Purpose

The purpose of this study is to prepare core-shell ferrites/kaolin pigments and compare their efficiency in protecting metal substrates to original ferrites. The new pigments are based on precipitating a shell of different ferrites that comprise only 10-20 per cent of the whole pigment on kaolin (core), which is a cheap and abundant ore comprising 80-90 per cent of the prepared pigment. These new pigments combine the properties of both its core and shell counter-parts, exhibiting improved corrosion protection properties. Furthermore, the pigments are represented as efficient, economically feasible and eco-friendly with comparable efficiency to that of original ferrites in protecting steel substrates.

Design/methodology/approach

The new pigments were characterized using different analytical and spectrophotometric techniques, e.g. transmission electron microscopy, energy-dispersive X-ray analysis and X-ray fluorescence. The pigments were then incorporated in epoxy-based paint formulations. The physico-mechanical properties of dry films and their corrosion properties were tested using accelerated laboratory tests in 3.5 per cent NaCl for 28 days.

Findings

The results of this study revealed that ferrite/kaolin core-shell pigments performance was almost close to that of the ferrite pigments in the protection of steel, and, at the same time, they confirmed good physico-mechanical properties.

Practical implications

These pigments can be applied in other polymer composites, e.g. rubber and plastics, as fillers and reinforcing agents.

Originality/value

Ferrite and ferrite/kaolin are environmentally friendly pigments, and they can impart high anticorrosive behavior to paint films with concomitant cost savings.

Details

Anti-Corrosion Methods and Materials, vol. 63 no. 1
Type: Research Article
ISSN: 0003-5599

Keywords

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Article
Publication date: 1 September 1992

S.M. El‐Sawy

Evaluation of Egyptian kaolin as a filler and extender pigment was carried out by measuring moisture content, water soluble salt content, hydrogen ion concentration…

Abstract

Evaluation of Egyptian kaolin as a filler and extender pigment was carried out by measuring moisture content, water soluble salt content, hydrogen ion concentration, specific gravity, bulking value, oil absorption, acid and alkali resistance, particle size distribution and particle shape, and comparing it with a commercial imported sample. X‐ray and chemical analysis were used for the identification of the pigments. It was found that it is economical to use the Egyptian kaolin for it as a natural white fine mineral that is available in quantity in a relatively pure state. The physical and chemical properties peculiar to Egyptian kaolin make it an ideal choice as a filler and extender pigment, this is in comparison with the commercial imported sample.

Details

Pigment & Resin Technology, vol. 21 no. 9
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 1 February 1996

Houssni El‐Saied, Snaa M. El‐Sawy and Altaf H. Basta

Reports on tests in which barium metaborate pigment and its modified form are prepared, identified by chemical and X‐ray diffraction methods, and specified according to…

Abstract

Reports on tests in which barium metaborate pigment and its modified form are prepared, identified by chemical and X‐ray diffraction methods, and specified according to standard methods. Evaluates the modified barium metaborate as a new filler for paper making by carrying out two series of experiments. Details the results which showed that the efficiency of the filler retention when using modified barium metaborate was higher than that of the other two conventional fillers. Reveals that at relatively low filler addition (2–5 percentage weight), higher improvement in the strength properties can be obtained when using the modified pigment instead of titanium dioxide and kaolin, but observes the reverse (i.e. a detrimental effect) at relatively high filler addition (8–10 percentage weight). Discovers that the optical properties of the modified pigment‐loaded sheets lie between those of titanium dioxide and kaolin. Shows that blending barium metaborate with kaolin or titanium dioxide has a significant effect on strength properties rather than optical properties. Concludes that modified barium metaborate pigment can be successfully used in paper filling applications and that modified barium metaborate pigment‐kaolin blend (80/20 per cent) can be used instead of titanium dioxide as a paper filler.

Details

Pigment & Resin Technology, vol. 25 no. 2
Type: Research Article
ISSN: 0369-9420

Keywords

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