Gardner colour

Unmodified aliphatic hydrocarbon resins softening point = 80-100°C, Gardner colour = 3.5-7. 

Aromatic hydrocarbon resins. The polymerization procedure and variables in the reactions of the aromatic hydrocarbon resins are similar to those for the coumarone-indene resins. However, the Cg feedstreams used in the polymerization of the aromatic hydrocarbon resins do not contain significant amounts of phenols or pyridine bases, so they are submitted directly to fractional distillation. Distillation produced more byproducts than light coal-tar oils. The aromatic hydrocarbon resins obtained have softening points between liquid and 125°C and Gardner colour of 6 to 11. By changing distillation conditions, aromatic hydrocarbon resins with softening points between 65 and 170°C and Gardner colour of 5 to 10 can also be obtained. 

Generally, the acrylic polyols, which are amorphous solids at room temperature, are used as solutions (40-100% solids), in various solvents, but sometimes, special structures, which are liquid at room temperature, are used without solvents (for example the structures very rich in butyl esters). The most used solvents for acrylic polyols are xylene, naphtha, butyl acetate, 1-methoxypropyl acetate, and butyl glycol. The viscosity of acrylic polyols varies from 1000-9000 mPa-s at 25 °C. The equivalent weight varies from 400-700 (OH number varies between 80-140 mg KOH/g). Due to the presence of acrylic acid units, the acidity of acrylic polyols is relatively high (2-5 mg KOH/g). Acrylic polyols have an excellent appearance, are very light in colour (they are practically colourless polyols), the Gardner colour frequently being < 1. 

The dark colour of polyether polyols obtained in the presence of imidazoles as catalysts (Gardner colour >18) can be improved substantially by the treatment with hydrogen peroxide (50% concentration) of around 0.1-0.3% against the polyol. The dark brown colour is the colour of the catalyst and it is not a consequence of polyether destruction. A better final colour is obtained using N-substituted imidazoles (such as N-methyl imidazole) [36]. 

One of the key properties of coumarone-indene resins is the softening point. This is determined by careful selection of the feedstock, manufacturing process, level of constancy in temperature during reaction and concentration of initiating system. Coumarone-indene resins which are obtained using this procedure have softening points from liquid to 170°C and Gardner colour of 5 to 9. 

The colour can be determined by various methods such as the Gardner, Barrett, iodine colour number or US Colophonium standard methods. Usually, the Gardner or the Barrett standards are used. A comparison between the different methods to determine the colour of resins is given in Table 9. In both methods, the colour is evaluated in resin solutions. A 50 wt% resin solution in toluene is used as the Gardner standard, and a solution of 2 g resin in 25 ml toluene is used in the Barrett... 

The different instruments (Hunter, Gardner, Instrumental Colour Systems, etc.) process absorbance and reflectance data in slightly different ways, which means that the values obtained can differ slightly from one instrument manufacturer to another. Therefore, a product s defined colour has to be qualified with a statement indicating the instrument used. Notwithstanding this limitation, it is not uncommon to find a tristimulus colour meter in a manufacturer s quality assurance laboratory so that routine quantitative assessment of a product s colour can be made. This is particularly tine for tomato-based products, whose nature makes conventional spectrophotometric assessment meaningless. 

In Example 1 the results of producing hydroxylammonium acid sulphate by the conventional process and by the process according to th< invention were compared. In the preparation by the conventional process, a mixture of 4.8 moles of 1-nitropropane and sufficient water tc-make a total of 4 moles with that present in the sulphuric acid wa.-prepared and heated to reflux. There was then added 4.0 moles oi sulphuric acid, either electrolytic grade, 93% or C.P. grade, 96%. Tin. addition was made very slowly over a 3 to 4-hour period and tlu refluxing of the completed mixture was continued for a total reaction time of 8 hours. The reaction mixture was then cooled to below ahoui 115° C. and the two layers separated. The lower layer oi hydroxylammonium acid sulphate layer was analysed for HAf (hydroxylammonium acid sulphate) content and its colour determincM on the Gardner 1933 Standard Colour Scale. The upper layer Oi propionic acid layer was analysed for total acidity which. was corrected for sulphuric acid and hydroxylammonium acid sulphate content ami the per cent, yield of propionic acid calculated therefrom. The results oi these experiments are set out in Table 1A below. 

According to Cielab scale, colours were determined employing a colorimeter BYK Gardner. 

The colour of an oil is generally measured by comparing it with a known standard. The Gardner method is commonly used in the surface coatings industry and consists of 18 standard colours which are available in the form of coloured glass supplied in various comparator units. 

Iodine value Acid value Unsaponifiables Resin acids Fatty acids Colour (Gardner)... 

Colour Mixed colour for two-part adhesives, colour after cure. Those shown as, e.g. white- clear, have a colour change on curing. Thermoplastics - may state a colour numerically to the Gardner Scale. Silicones Various -several colour available, but product code may differ for coloured variants. 

Company Adhesive Base Form Colour (Gardner) Soft. Temp (V Application Temp( C) Assembly Time (sec) Service SG TS El. (%) Pg. No. 

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