Paint bulk properties

Polymer surface modifications are omnipresent in applications where the surface properties of materials with favorable bulk properties are insufficient. By altering the surface characteristics using physical or chemical modification the desired surface properties may be achieved. Such treatments are required e.g. to enhance printability of films, the adhesion of paints, metal or other coatings, biocompatibility, protein resistances/reduced biofouling, etc. The diverse approaches met in practice include, among others, wet chemical and gas phase chemistry, plasma or corona, UV/ozone and flame treatments. In most cases surface chemical modification reactions take place that alter the surface energy in a desired way. For example,... 

Basic Operations in Paint Manufacture Oil Absorption and the Milling Process Bulk Properties of Paints Types of Mills for Paint Manufacture Stone and Colloid Mills Roller Mills Ball and Pebble Mills Sand Mills... 

CAS 471-34-1 EINECS/ELINCS 207-439-9 Uses Filler, extender for plastics, caulks/sealants, rubber, adhesives, ceramics, paper, cleansers, paints/coatings Properties Powd. 3 median particle size 99%. finer than 20 , 50%. finer than 3 fineness (Hegman) 6 dens. 22.6 Ib/solid gal bulk dens. 50 Ib/ff (loose) oil absorp. 15 brighfness 92 Hubercarb W 4 [Huber Engineered Materials Akrochem]... 

Thin polymer films are generally obtained by solution casting, in many applications, such as paints, varnishes, or adhesives. The properties of polymer films obtained from a solution differ from the original bulk properties, and this effect can have some significant consequences on the expected behavior of the final film. 

The most common infrared sampling techniques used to examine paint samples are attenuated total reflectance and photoacoustic spectroscopies. Liquid paints, dried films and paint chips may all be investigated in this way. Depth profiling can be useful when examining paint, as the surface properties will vary importantly from the bulk properties. In addition, most paint films contain two or more layers with different compositions, and so reflectance techniques are necessary for the characterization of individual layers. 

Other techniques are used to identify pigments based on their molecular fragments. These techniques include UV-visible reflectance spectroscopy, infrared (IR) spectroscopy, mass spectrometry, and X-ray diffraction (XRD). Some thermal methods exploit differences in physical characteristics that are sensitive to the bulk properties of a paint sample. Differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) are often used. Finally, separation techniques such as liquid chromatography (LC) have been used to identify a wide range of dyes. 

In surface hydrophobization, a film is formed on the coating, the film thickness possibly being 1000 A. This nonremovable film gives the surface hydrophobic properties. Bulk modification of the coating is achieved by incorporating various reagents in the paint or varnish before application. The use of such techniques modifies the bulk properties of the coating as well as surface properties. 

In a recent case study (see Svendsen et al, 2007 and also Problem 6.1), in collaboration with a paint company, the adhesion of six different epoxies-silicon systems has been studied. These paints are used in marine coating systems. Some epoxies showed adhesion problems in practice while others did not. The purpose of the study was to understand the origin of these problems and whether adhesion could be described/ correlated to surface characteristics, e.g. surface tensions. An extensive experimental study has been carried out including both surface analysis (contact angle measurements on the six epoxies, surface tension of silicon at various temperatures, atomic force microscopy (AFM) studies of the epoxies), as well as measurements of bulk properties (pull-off adhesion tests and modulus of elasticity). Theoretical analysis included both estimation of Zisman s critical surface tensions and surface characterization using the van Oss-Good theory. 

Oxides comprise a very diverse class of compounds with properties covering almost all aspects of material science and physics. Oxides can be both superconductors and insulators. The bonding characteristics may be classified as covalent for one system and highly ionic for the other. Oxides find applications in many fields of technical interest, from paint pigments via nonlinear optics to sensors and catalysis. In some cases, the bulk properties are important, as, for example, very often in nonlinear optics in other cases, the surface properties play a major role, as in catalysis. 

A useful property of liquids is their ability to dissolve gases, other liquids and solids. The solutions produced may be end-products, e.g. carbonated drinks, paints, disinfectants or the process itself may serve a useful function, e.g. pickling of metals, removal of pollutant gas from air by absorption (Chapter 17), leaching of a constituent from bulk solid. Clearly a solution s properties can differ significantly from the individual constituents. Solvents are covalent compounds in which molecules are much closer together than in a gas and the intermolecular forces are therefore relatively strong. When the molecules of a covalent solute are physically and chemically similar to those of a liquid solvent the intermolecular forces of each are the same and the solute and solvent will usually mix readily with each other. The quantity of solute in solvent is often expressed as a concentration, e.g. in grams/litre. 

A useful way of classifying chemicals is shown in Fig. 2.1. Chemicals are divided on the basis of volume and character. Bulk chemicals, or commodities, are produced in large quantities and sold on the basis of an industry specification. There is essentially no difference in the product from different suppliers. Typical examples would be acetone, ethylene oxide, and phenol. Pseudo commodities are also made in large quantities but are sold on the basis of their performance. In many cases the product is formulated and properties can differ from one supplier to another. Examples include large volume polymers, surfactants, paints, etc. 

Horn has many of the same properties as tortoiseshell but is much cheaper and easily accessible. It has been used to add bulk to tortoiseshell by welding the two materials together, for example as a small box with tortoiseshell on the outside, or just on the lid. Horn can be dyed to resemble tortoiseshell, but this takes considerable skill. The horn is hot pressed (which partially destroys the fibrous nature of the material), then boiled in nitric acid to give it a yellow hue. After neutralising it is painted by hand. Examination shows that the colour is only on the surface, and brush strokes may be visible. 

---