Лако-красочные материалы — производство

The potential value of the application of molecular orbital methods in colour chemistry is immense. In essence, the reason for this is that the methods enable, in principle, many of the light absorption properties of dyes, from a knowledge of their chemical structure, to be calculated with the aid of a computer. Thus, the colour […]

The valence-bond (or resonance) approach to bonding in organic mol­ecules is a particularly useful approach to explaining the properties of aromatic compounds. The approach involves postulating a series of organic structures that represent a particular compound in each of which the electrons are localised in bonds between atoms. These structures are referred to as canonical, […]

Since the discovery of the first synthetic dyes in the mid-19th century, chemists have been intrigued by the relationship between the colour of a dye and its molecular structure. Since these early days, the subject has been of special academic interest to those fascinated by the origin of colour in organic molecules. In addition, an […]

Colorants may be classified usefully in two separate ways, either accord­ing to their chemical structure or according to the method of application. The most important reference work dealing with the classification of dyes and pigments is the Colour Index, a publication produced by the Society of Dyers and Colourists, Bradford, England. This series of volumes […]

Colour may be introduced into manufactured articles, for example tex­tiles and plastics, or into a range of other application media, for example paints and printing inks, for a variety of reasons, but most commonly the purpose is to enhance the appearance and attractiveness of a product and improve its market appeal. Indeed it is often […]

Most dyes and pigments owe their colour to the selective absorption of incident light. In some compounds, colour can also be observed as a result of the emission of visible light of specific wavelengths. These compounds are referred to as luminescent. The most commonly encoun­tered luminescent effects are fluorescence and phosphorescence. The transitions which can […]

The most obvious requirement of a dye or pigment to be useful in its applications is that it must have an appropriate colour. Of the many ways in which light can interact with objects, the two most important from the point of view of their influence on colour are absorption and scattering. Absorption is the […]

It is commonly stated that there are fifteen specific causes of colour, arising from a variety of physical and chemical mechanisms. These mech­anisms may be collected into five groups. (a) Colour from simple excitations: colour from gas excitation (e. g. vapour lamps, neon signs), and colour from vibrations and rota­tions (e. g. ice, halogens); (b) […]

The sensation of colour that we experience arises from the interpretation by the brain of the signals that it receives via the optic nerve from the eye in response to stimulation by light. This section contains a brief descrip­tion of the components of the eye and an outline of how each of these contributes to […]

Visible light refers to the region of the electromagnetic spectrum to which our eyes are sensitive and corresponds to radiation within the very narrow wavelength range 360-780 nm. Since the sensitivity of the eye to radiation is very low at each of these extremes, in practice the visual spectrum is commonly taken as 380 to […]