Kauri number

The aniline point determination is another method of establishing the solubilizing power of a solvent by simple means. Here, the temperature is measured at which a solution just becomes eloudy. Figure 2.3.21 shows that there is a good correlation between the Kauri number and the aniline point. Also dilution ratio of cellulose solution is measured by standardized methods (see Chapter 15). 

In addition to shellac a number of other natural resins find use in modem industry. They include rosins, copals, kauri gum and pontianak. Such materials are either gums or very brittle solids and, although suitable as ingredients in surface coating formulations and a miscellany of other uses, are of no value in the massive form, i.e. as plastics in the most common sense of the word. 

Kauri-butanol number A measurement of solvent strength for hydrocarbon solvents the higher the Kauri-butanol (KB) value, the stronger the solvency the test method (ASTM D1133) is based on the principle that Kauri resin is readily soluble in butyl alcohol but not in hydrocarbon solvents and that the resin solution will tolerate only a certain amount of dilution and is reflected as cloudiness when the resin starts to come out of solution solvents such as toluene can be added in a greater amount (and thus have a higher KB value) than weaker solvents such as hexane. 

The solvency of hydrocarbon solvents used in paint and lacquer formulations is empirically described by their kauri-butanol numbers, that is, the volume in milliliters... 

Prior to the introduction of the solubility parameter (solpar) concept, paint chemists used Kauri butanol values, mixed aniline points, and heptane numbers to predict the solubility of resins in aliphatic solvents. These parameters have been replaced, to a large extent, by solpars, but heptane numbers are still used, and these empirical parameters can be converted to solpar values. 

The solvency of hydrocarbon solvents used in paint and lacquer formulations is empirically described by their kauri butanol numbers, i.e. the volume in milHliters at 25 °C of the solvent required to produce a defined degree of turbidity when added to 20 g of a standard solution of kauri resin in 1-butanol [120]. Standard values are KB = 105 for toluene and KB = 40 for -heptane/toluene (75 25 cL/L). A high KB number corresponds to high solvent power. An approximately linear relationship exists between Hildebrand s 8 values and KB numbers for hydrocarbons with KB >35 8 = Q.Q6-KB+U.9 [99, 177]. 

There is a good discussion of the theory and application of various kinds of solubility parameters at http //palimpsest. stanford.edu/byauth/burke/solpar/. There are a belwindering array of solubility parameters, such as Kauri-Butanol number. 

The test method for the determination of aniline point and mixed aniline point of hydrocarbon solvents (ASTM D-611, IP 2) is a means for determining the solvent power of naphtha by estimating of the relative amounts of the various hydrocarbon constituents. It is a more precise technique than the method for kauri-butanol number (ASTM D-1133). 

The results obtained by the kauri-butanol test (ASTM D-1133) depend on factors other than solvent power and are specific to the solute employed. For this reason, the aniline point is often preferred to the kauri-butanol number. 

Existing methods use physical measurements and require suitable standards. Tests such as aniline point (ASTM D-611) and kauri-butanol number (ASTM D-1133) are of a somewhat empirical nature and can serve a useful function as control tests. Naphtha composition, however, is monitored mainly by gas chromatography, and although most of the methods may have been developed for gasoline (ASTM D-2427, ASTM D-6296), the applicability of the methods to naphtha is sound. 

The solubility parameter is a blendable property so its value for a blend can be calculated and a blend of solvents can be made to suit the solute more closely if necessary. While the value of 5can be calculated knowing only readily available information, it can also be found experimentally for hydrocarbons and chlorinated hydrocarbons by measuring the Kauri Butanol number [KB) since... 

Two standard tests. Kauri butanol (KB) number and dilution ratio, involving simple laboratory equipment can be used and there is a fair correlation (Fig. 13.4) between the former and the Hildebrand solubility... 

DOWANOL ViseosityofS% nitrocellulose solutions in DOWANOL glycol ethers, eentlstokes atTTF Blush Conditions Dilution Ratios Kauri Butanol Number... 

Figure 2.3.20. Kauri butanol number vs. Hildebrand solubility parameter.

Simpler methods are also used. In the paint industry, Kauri butanol values are determined by establishing the tolerance of a standard solution of Kauri resin in n-butanol to the addition of diluents. This method is applicable to hydrocarbons (both aromatic and aliphatic) and CFCs. Figure 2.3.20 shows that there is a good correlation between the Kauri butanol number and the Hildebrand solubility parameter. The Kauri butanol number can be as high as 1000 (amyl ester of lactic acid) or 500 (Freon solvent M-162). 

Also the paint industry, formerly the main end-user of solvents, attempted to produce a quantitative solvent power data system [5]. This related solvency to certain standard solutes, used in their industry. These could either be a well-known natural (Kauri-resin) or later a synthetic (nitrocellulose) paint binder. The result was the introduction of the Kauri-Butanol number, which applies to hydrocarbon solvents only and the NC-dilution ratio which is used for oxygenated solvents. Another test, used in conjunction with hydrocarbon solvents, is based on the fact that aniline is hardly miscible with aliphatic hydrocarbons but mixes very well with aromatics. The Kauri-Butanol (KB) number as defined in ASTM D 1133 is a measure of the tolerance of a standard solution of Kauri resin in -butanol to hydrocarbon diluent. Standard hydrocarbon solvents used to calibrate the Kauri solution are toluene (KB-number 105) and a 75% v -heptane/25% v toluene blend (KB-number 40). The KB-value increases from approx. 20 to over 100 in the order ... 

---