Drying of soap

Liquid Diffusion The movement of liquids by diffusion in sohds is restricted to the equilibrium moisture content below the point of atmospheric saturation and to systems in which moisture and solid are mutually soluble. The first class applies to the last stages in the drying of clays, starches, flour, textiles, paper, and wood the second class includes the drying of soaps, glues, gelatins, and pastes. 

Coconut oil [8001-31-8] is one of the primary vegetable oils used in the manufacture of soap products. Coconut oil is obtained from the dried fmit (copra) of the coconut palm tree. The fmit is dried either in the sun or over open fires from burning the husks of the fmit, with the oil pressed out of the dried fmit. 

For sodium palmitate, 5-phase is the thermodynamically preferred, or equiUbrium state, at room temperature and up to - 60° C P-phase contains a higher level of hydration and forms at higher temperatures and CO-phase is an anhydrous crystal that forms at temperatures comparable to P-phase. Most soap in the soHd state exists in one or a combination of these three phases. The phase diagram refers to equiUbrium states. In practice, the drying routes and other mechanical manipulation utilized in the formation of soHd soap can result in the formation of nonequilibrium phase stmcture. This point is important when dealing with the manufacturing of soap bars and their performance. 

Soap as used in personal cleansing products has a long safe history of use. Modem soaps have been specifically formulated to be compatible with skin and to be used on a daily basis with minimal side effects. Excessive use of soap for skin cleansing can dismpt the natural barrier function of skin through the removal of skin oils and dismption of the Hpid bdayer in skin. This can result in imperfect desquamation or a dry appearance to skin and cause an irritation response or erythema, ie, reddening of the skin. Neither of these is a permanent response and the eHcitation of this type of skin reaction depends on the individual s skin type, the product formulation, and the frequency of use. 

One principal use of cyclohexanol has been in the manufacture of esters for use as plasticizers (qv), ie, cyclohexyl and dicyclohexyl phthalates. In the finishes industry, cyclohexanol is used as a solvent for lacquers, shellacs, and varnishes. Its low volatiUty helps to improve secondary flow and to prevent blushing. It also improves the miscibility of cellulose nitrate and resin solutions and helps maintain homogeneity during drying of lacquers. Reaction of cyclohexanol with ammonia produces cyclohexylamine [108-91-8], a corrosion inhibitor. Cyclohexanol is used as a stabilizer and homogenizer for soaps and synthetic detergent emulsions. It is used also by the textile industry as a dye solvent and kier-boiling assistant (see Dye carriers). 

Fig. 7. Plant for spray-drying of detergents and soaps. 1, Burner 2, air combustion 3, cold air fan 4, hot air generator 5, spray-drying tower 6, cleaning ring 7, no22les circuit 8, tower suction cyclones group 9, tower suction fan 10, double-flap dischargers 11, recovery powder cyclone 12, recovery powder fan 13, belt conveyor 14, air lift 15, air lift suction cyclones 16, air lift suction fan 17, double-flip dischargers 18, vibrating sieve.

Cobalt. Without a doubt cobalt 2-ethyIhexanoate [136-52-7] is the most important and most widely used drying metal soap. Cobalt is primarily an oxidation catalyst and as such acts as a surface or top drier. Cobalt is a transition metal which can exist in two valence states. Although it has a red-violet color, when used at the proper concentration it contributes very Httie color to clear varnishes or white pigmented systems. Used alone, it may have a tendency to cause surface wrinkling therefore, to provide uniform drying, cobalt is generally used in combination with other metals, such as manganese, zirconium, lead, calcium, and combinations of these metals. 

Powdered-product collection, as in pneumatic conveying the spray drying of milk, eggs, and soap and the manufacture of nigh-purity zinc oxide and carbon black... 

Wt % AOS in soap (dry basis) % Increase in the solubility of soap in water... 

The important but unusual fatty acid ricinoleic acid, or 12-hydroxyoleic acid, is a major component of castor oil (>87%) and is also found in useful quantities in ergot. The metal salts of the acid find use in dry-cleaning soaps but the majority is converted to aminoundecanoic acid (Scheme 6.6) which is used to make nylon 11. Nylon 11 has very good chemical and shock-resistance properties, which have led to it being used in the automotive industry. Ricinoleic triglyceride is initially transesterified to the methyl ester. This is heated to 300 °C at which temperature it is... 

Next morning, when the material has cooled, the solid cake of soap is lifted out and washed to remove adherent alkali. It may be cut into small pieces by means of a thin wire and then left to dry for several weeks. 

Soap chips are made by running a thin sheet of melted soap onto a cool cylinder and scraping off the soaps in small broken pieces. Soap granules are dried miniature soap bubbles. Soap powders and scouring soaps contain some soap, a scouring agent (abrasive) such as powdered pumice or finely divided sand, and builders like sodium carbonate and trlsodlum phosphate. Builders make the soaps act more rapidly. The cleansing action of soap has been discussed in Unit 5. 

Uses/Sources. Production of rubber-processing chemicals corrosion inhibitor in boiler feed water production of insecticides, plasticizers, and dry cleaning soaps a metabolite of the sweetener cyclamate... 

The same chemist patented somewhat Later (Ref 1, p 343) four expls contg K chlorate or perchlorate with "solidified oil (huile solidifiee), which was prepd by adding to 100 parts of soap (completely dried at 120—130°), 10 to 15 parts of castor oil and then continuing to heat for 2—3 hrs... 

While absorption is a valuable quality, more often than not absorption capacity is used to carry solutes into the matrix of a foam. If this is done after the foam is produced, the process is referred to as imbibing. It is sometimes advisable to add the solute to the water phase used to produce the polyuretliane. As long as the solute is not reactive with the prepolymer, the solute is deeply imbedded into the foam matrix. The imbibing process has a tendency to place the solute closer to the surface. The purpose is usually delivery in a controlled manner. The simplest example is to imbibe a liquid soap into a foam that is then dried. The soap diffuses out when the foam is wet. 

---