Safe handling of colorants: hazard classification and selection of occupational hygiene strategies

Since the introduction of the COSHH regulations, manufacturers have been required to assess the risks associated with their operations. A major problem facing manufacturers in the coloration industry, however, has been the ambiguous terms of reference against which they can carry out effective assessment. The Chemical Industries Association Dyes Sector group has responded to this by drawing up a system of hazard classification and a selection of appropriate occupational hygiene strategies. The following article, prepared by the group previews a detailed guideline due to be published in the near future.     

Acquisition and use of data for assessment of the environmental impact of colorants

The Notification of New Substances Regulations 1982 require information about new chemicals to be submitted to the national competent authority prior to placing them on the European Community market. The information must be of sufficient quantity and quality to allow an assessment to be made of the new chemical's impact on the environment. The data given in the notification need to be supplemented with information about the use, release and behaviour of the new chemical. For dyes this was collected during a survey of the industry, to produce estimates of environmental concentrations. These are compared with the concentrations at which adverse effects have been recorded in ecotoxicity tests, to make an initial assessment of the effect of manufacturing and using the new chemical.     

焦油管式炉结焦的预防及处理

阐述了管式加热炉炉管结焦的机理及危害,分析了焦油管式炉结焦的原因,通过改进机械化焦油氨水澄清槽、提高二次蒸发器过热蒸汽量、降低管式炉辐射段出口温度和燃烧法清理结焦炉管等措施,解决了炉管频繁结焦问题。     

液氯槽车充装风险的防范

阐述了氯气的危害以及氯气泄漏应采取的一般防护措施;列举了氯气泄漏案例,重点介绍了河南神马氯碱发展有限责任公司防止液氯槽车充装时泄漏的具体方法和措施。     

Acetoacetanilide colorants: intramolecular bonding and their relationship with pyrazolone colorants

The possibility of C.H.O intramolecular bonds in acetoacetanilide colorants is considered. It is concluded that such bonds play an important part in keeping the molecular planar. A close relationship between the molecular configurations of acetoacetanilide and pyrazolone colorants is noted, and it is suggested that the printed representation of the former should be changed.     

Extraction and use of pigments from maize grains (Zea mays L) as colorants in yogur

The aim of the present work was to determine the potential use of anthocyanins from maize grains as colorants in yogurt. Pigments were extracted from four native maize varieties (Arrocillo, Peruano, Purepecha and Cónico), which possess a high anthocyanin concentration in the pericarp. Pericarp and aleurone layer were mechanicallly removed from grain using a Strong-Scott barley pearled. Yields of pericarp and aleurone layer fraction (PALF) were evaluated. Total anthocyanin content in this fraction was determined by a conventional spectrophotometric method and the anthocyanin profile was obtained by HPLC. One mg of anthocyanin extracts from the PALF was added to 100 g of a commercial plain yogurt. Yogurt samples were kept under refrigerated conditions and color and pH were monitored every 5 days interval, during three weeks. The yields of PALF were 48.4%, 55.1%, 40.2%, and 40.0% for Arrocillo, Peruano, Cónico and Purepecha varieties, respectivelly. The highest total anthocyanin content (259.4 mg of anthocyanins/100 g sample) was observed in Peruano PALF. The color of yogurts dyed with each of the four extracts was different. Yogurts dyed with Peruano and Arrocillo extracts showed a more intense reddish tone than those dyed with Cónico and Purepecha. After 5 to 10 days under refrigerated storage, the color of all yogurt samples changed to a slight yellowish tone according to the Hue values, Nevertheless, these changes were not visually evident.     

Synthesis of novel polymeric colorants

There are several structural types of polymeric dyes (polydyes) that have been synthesised as colorants for thermoplastic materials, particularly polyesters. This paper reviews three synthetic methods used to prepare polydyes. In method 1, anthraquinone polysulphonamide polydyes were prepared by reacting anthraquinonedisulphonyl chlorides with diamines in the presence of a base. Polymethine polydyes were prepared in method 2 by reacting bis-aldehydes containing two linked aromatic aldehyde moieties with a bis-(active methylene) component under Knoevenagel reaction conditions. In the final method, a variety of polymer types were synthesised by reacting acidic dyes containing two acidic groups with glycol sulphonates in the presence of a base. Most of the polydyes were evaluated as colorants for polyesters, by melt blending and extruding, followed by the preparation of films for further testing of properties such as fastness to light. The primary emphasis of this paper is to discuss the synthetic methods involved and to present the various types of structure that have been investigated.     

Measurement of specific surface of colorants in cellulose

A new method is described whereby the specific surface of colorants, i.e. pigments or insoluble or water-soluble dyes, in cellulose can be measured. The principle of the method is the selective adsorption of p-nitrophenol (PNP) from water by the colorant particles but not by the cellulose, thus permitting determination of the surface of the particles and the effect thereon of various treatments. Results with organic pigments in spun-dyed viscose rayon agree with calculations of specific surface from particle-size analysis of the pigments before incorporation. This shows that the whole surface of the colorants in the cellulose is accessible to PNP and thus measurements can be made with a variety of dyes. Azoic dyes and vat dyes give results that correspond to average particle diameters of ～ 0.1–0.6 μm and the method detects the increase in their particle size on soaping. A direct cotton dye of low light fastness and a reactive dye give specific surface values much too low for a monolayer and they appear to exist as multilayers in cellulose. A direct cotton dye of high light fastness appears to be present as three-dimensional aggregates of diameter ～ 0.08 μm, in agreement with published electron micrograph values for similar dyes.