Tung oil drying

Synthetic Conjugated Oils. Tung oil dries rapidly, but is expensive, and its films discolor rapidly due to the presence of three double bonds. These defects led to efforts to synthesi2e conjugated oils, especially those containing esters of fatty acids with two conjugated double bonds. 

Problem 33.3 In paints, tung oil dries faster than linseed oil. Suggest a reason Why. (See Table 33.1.)... 

Dicyclopentadiene/linseed oil copolymer drying oil, printing inks Castor oil, dehydrated Tung oil drying oil, protective coatings Castor oil, dehydrated... 

Compared to linseed oil, a film of tung oil (conjugated) requires 48-72 h to dry without added driers with driers added, the same tung oil dried in l h. 

Tung oil is fully absorbed into a cotton cloth, 0.5 cm thick, and suspended in dry air at a uniform temperature. The properties of the tung oil and wet cloth are given below ... 

The earliest synthetic resin to be used in commerce seems to have been a polyester then termed ester gum, which was made by esterifying rosin (essentially an unsaturated monocarboxylic terpenoid acid, abietic acid) with glycerol. When cooked with tung oil (a glycerol ester of 9,11,13-octadecatrienoic acid), this provided varnishes that dried overnight. In this case, the polymer is formed by an addition copolymerisation process, but the product is nevertheless also a polyester. 

It was found that they are useful not only in nitrated form, but also straight in manuf of resins, plastics and for drying oils (to replace the imported tung oil) in paints and varnishes Following is a list of papers published during and after WWII on prepn and props of DPE and of other Polypentaerythritols ... 

Burrell prepd, in addition to DPE of mp 219-222°, TPE of mp 242-248°, a product of mp 230—240°, which proved to be a mixture of DPE TPE with probably TePE (tetrapenta-erythritol). He named this mixture the Pleo-pentaerythritol. Esterification of these technical Polypentaerythritols, (called by Heyden Co the Polypenteks) by heating with fatty acids (such as linseed) in the presence of alcohols (such as erythritol) produced drying oils, suitable as a replacement of tung oil in paints and varnishes... 

The Inks used In currency printing are complex formulations based on natural drying oils such as tung oil and linseed oil. These oils contain multiple double bonds which act as polymerization sites when exposed to oxygen. Although the details of the chemistry are not fully understood, some Important observations can be made. If a bulk Ink sample Is exposed to air for several days a hard skin forms on the surface. Underneath this skin, however, the mechanical properties of the Ink remain virtually... 

Low-odour inks for food packaging are based on odour and taint-free substances, for example, aromatic free solvents and maleic resins. So called semi-drying oils are also used. These are slow to oxidise and therefore do not develop malodorous aldehydes as they dry. However, some smell may be noticed after a long period of time as oxidation proceeds. Other solvents, such as tung oil, develop quite some odour during drying but if properly... 

Dehydration of castor oil and of castor acids gives products enriched in diene acids, some with conjugated unsaturation. These products are valuable alternatives to drying oils such as tung oil. 

Oiticica (Licania rigida). The kernel oil obtained from this Brazilian tree is characterized by its high level ( 78%) of licanic acid (4-oxo-9cllfl3f-octadeca-trienoic acid)—a keto derivative of the more familiar eleostearic acid. The oil shows drying properties but does not dry as quickly as tung oil (156). 

Oils containing Cjg polyene acids Calendula officinalis seed oil. Calendula oil (from marigold) is of interest because it contains about 58% of calendic acid (8fl0fl2c-18 3). This unusual acid is an isomer of a-eleostearic (9cllfl3f-18 3) present in tung oil, and calendula oil should also be a good drying oil. The presence of linoleic acid (30%) will add to the unsaturated nature of this oil (131-133). 

On the other hand, the high degree of unsaturation of this type of drying oil has made it a potential monomer for polymerization into useful polymers. More recently, Li and Larock (41) reported the conversion of tung oil to solid polymers by cationic copolymerization with divinylbenzene as a comonomor. The resulting polymers have proven to be thermosetting materials with good mechanical... 

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