Search results

The number of articles on solvent‐based acrylic resins in the paint industry has decreased in the past two years. It is not entirely clear why this is, since acrylic resins serve a key function in the industrial coatings segment of the paint industry, because of their outstanding weathering performance. The fact that they are available in both thermoset and thermoplastic forms makes them highly versatile. Structurally they are capable of wide variation, as indicated by an article by Ailhaud [Peintures, Pigments, Vernis, 47, March (1971) p. 170] who reports on the properties of block copolymers based on a variety of different alkyl methacrylates.

The purpose of this paper is to study properties of intumescent coatings based on a silicone‐epoxy hybrid resin (with an aminosilane as hardener). In the first part of this study, fire‐resistance behaviour of the intumescent coating based on silicone‐epoxy resin containing intumescent additives is evaluated. The second part assesses the effect of mineral fibres on fire‐resistant properties of intumescent coatings based on the silicone‐epoxy resin.

Thermal degradation and char formation of coatings were investigated by Thermogravimetric analyses, X‐ray diffraction and X‐ray fluorescence and infrared spectroscopy (FTIR). The salt spray corrosion test was applied to study the resistance of intumescent coatings. Anticorrosion and fire‐resistant properties after one, three and seven days of exposure were evaluated.

It was shown that a silicone‐epoxy hybrid resin is suitable for applications in the field of intumescent coatings. Intumescent coatings based on this resin form a thermally stable thin ceramic‐like layer, which improves the thermal insulation properties of the char. Mineral fibres reinforced the char structure and thus improved fire‐resistant properties of intumescent coating before as well as after the salt spray test. Mineral fibres also improved anticorrosion properties.

This paper discusses only the effect of mineral fibres on properties of intumescent coatings.

A silicone‐epoxy hybrid resin has not previously been used in intumescent coatings. This type of intumescent coating can be used as an effective passive fire protection system for steel constructions.

Epoxy resins have probably provided more interesting chemistry than any other polymer the paint industry uses. In this category of interesting chemistry is Russian work [World Surface Coatings Abstracts (1978) Abstract No. 1558] which describes the preparation of structurally coloured epoxy resins — i.e. of epoxy resins which are inherently coloured. The work involves condensing bisphenol A and epichlorohydrin in the presence of small amounts (0.1 to 0.5 weight per cent) of a coloured co‐monomer dye. The dye, for example, can be the glycidyl ether of alpha aminoanthroquinone. Coloured products resulted which presumably would provide coatings with intrinsic colour. Of course, this colour could be modified by extrinsic dyes and pigments. The concept of producing coloured polymers is not a new one. One approach to making black polyethylene for black film is to carry out the polymerisation of the ethylene in a fluid bed of carbon particles. The carbon particles presumably serve as a nucleus around which the polymer forms and at the same time serves to impart a black colour to the polymer particle. This technology has never been commercialised but it is certainly of interest to the paint chemist for it presents a new concept in carrying out a major objective of the paint industry — namely, to impart colour to solutions of polymers.

Alkyd resins are among the most mature raw materials the protective coatings industry uses. At the same time they are the largest volume oil‐based vehicles used in paints around the world. This might raise the question “is there anything really new with alkyds?” The answer is a resounding “yes!” There is new commercial as well as technical activity. In the former category one finds activity in the Arab world where oil‐based affluence has created a need for protective coatings raw materials. Thus in Jordan a company known as Universal Chemical Industries has set up to produce alkyd resins as well as poly(vinyl acetate) emulsions with the objective of supplying the domestic coatings industry. Technology comes from Ashland Chemicals' European subsidiaries. Similarly, in Saudi Arabia, Arabian Gulf Resins International announced plans to build a large alkyd resin plant at Damman using Deutsche Texaco's technology.

Behind every successful technology is a great body of scientific knowledge. The paint industry managed to get along pretty well from the time of the Egyptians until World War I, a span of approximately 5,000 years, without much scientific insight. Indeed, the empirical approach to paint formulation could hardly be criticised. When one visits museums of Egyptology today, one sees coatings formulated three to five thousand years ago which are bright coloured and which still have good adhesion and film integrity. But coating mummy cases in a very dry climate is considerably less demanding than coating missiles which find themselves in a hostile environment. Although paint for mummy cases, houses, and barns and even the first assembly‐line‐produced automobiles could be made without much scientific understanding, it is fair to say that coatings for the exacting demands of modern technology could never have evolved without an understanding of the scientific principles on which the modern coatings industry is based. The scientific basis for the modern coatings industry is found in an understanding of polymer chemistry, an understanding of the chemistry of solvents, a knowledge of the chemistry of pigments, and a large body of physical chemistry relating to solubility, rheology, adhesion, cohesion, and many other important phenomena.

The coatings industry is based on a large number of scientific principles. To be sure, it developed both in ancient and modern times without regard to these. But once an empirical body of knowledge was built up, it became obvious that theoretical underpinnings were not only desirable but necessary if progress were to be made. What are some of the scientific principles which govern coatings technology? Film formation is certainly one. What causes a film to form, and what affects the properties of a film such as cohesion, adhesion, gloss, flexibility, permeability, impact resistance, and a dozen other characteristics? The problem of understanding film formation became all the more important with the advent of waterborne paints, for polymer particles suspended in water are not nearly as prone to form films as are polymer solutes in a solvent.

The coatings industry is in large measure a function of the world around it. Advances in related disciplines are scrutinised carefully by coatings chemists because of the ramifications that these new discoveries and inventions may have if applied directly to the coatings area. This is certainly true relative to new resins and other raw materials. It applies also to the development of new energy forms which reflect themselves in new ways to cure coatings. Accordingly, some of these newer advances which could eventually have important ramifications in the coatings industry will be reviewed here.

The number of new alkyd resin‐based coatings introduced decreases yearly. To be sure, alkyd resins are the most important vehicles used for solvent‐based paints. On the other hand, the technology is mature and the major variations in the products are those which must be made to accommodate needs of the user. For the most part, these do not lead to completely new types of compositions.

Reducing Level of Alcohol in Inks ‐ A medium‐sized US ink manufacturer recently needed to reduce the level of alcohol in its bases for water‐based inks. Ciba Geigy Pigments Division's Inks Technical Centre developed an improved formulation, containing half the alcohol of the previous one and 40 per cent more pigment to allow the ink producer to meet VOC limits and increase production efficiency, at no additional cost.

Polymeric systems based on polyesteramides (PEA) are high performance materials, which combine the useful properties of polyester and polyamide resins, and find many applications, most importantly as protective surface coatings. The purpose of this paper is to characterise and evaluate new modified anti‐corrosive PEA resins for use in protective coating formulations.

In the study report here, new modified PEA compositions were prepared and evaluated as vehicles for surface coating. The PEA resins were obtained by means of a condensation polymerisation reaction between phthalic anhydride (PA) and N,N‐bis‐(2‐hydroxyethyl) linseed oil fatty acid amide (HELA) as the ingredient source of the polyol used. The phthalic anhydride was partially replaced with N‐phthaloylglutamic acid NPGA as the ingredient source of the dibasic acid. The structure of the resin was confirmed by FT‐IR spectral studies. Coatings of 50±5 μm thickness were applied to the surface of glass panels and mild steel strips by means of a brush. The coating performance of the resins was evaluated using international standard test methods and involved the measurement of phyisco‐mechanical properties and chemical resistance.

The tests carried out revealed that the modified PEA based on N‐phthaloylglutamic acid (NPGA) enhanced both phyisco‐mechanical and chemical properties. Also, the resins were incorporated within primer formulations and evaluated as anti‐corrosive single coatings. The results illustrate that the introduction of N‐phthaloylglutamic acid, within the resin structure, improved the film performance and enhances the corrosion resistance performance of PEA resins.

The modified PEA compounds can be used as binder in paint formulations to improve chemical, physical and corrosion resistance properties.

Modified PEA resins are cheaper and can be used to replace other more expensive binders. These modified PEA resins can compensate successfully for the presence of many the anticorrosive paint formulations and thus lower the costs. The main advantage of these binders is that they combine the properties of both polyester and polyamide resins based on nitrogenous compound, are of lower cost, and they also overcome the disadvantages of both its counterparts. Also, they can be applied in other industrial applications.