Acetate Butyrate

Cellulose butyrate contains the bulkier butyryl group these esters are more compatible and soluble than acetates, but are too soft for most coating applications. Cellulose esterified with blends of alkyl groups can provide many intermediate properties needed in coatings. Selection of the appropriate cellulose acetate butyrate [9004-36-8] (CAB) and cellulose acetate propionate [9004-39-f] (CAP) content must be based on specific application requirements. 

Following esterification and hydrolysis, the product undergoes additional manufacturing steps that include filtration, precipitation, washing, and drying. The final product is usually a dry, free-flowing powder. 

Tennessee Eastman is presently the world s only manufacturer of CAB and CAP. Table 2.2 lists the properties of the commercially available CAB and CAP products. 

Properties. The large size and low polarity of the butyryl groups separate the cellulose chains and lowers the attraction between them. As butyryl content increases, properties are affected as follows  

2) Tolerance for diluents increases (tolerance signifies the ability to withstand inclusion of a nonsolvent in the solvent system before haze or precipitation occurs) 

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Cellulose-acetate-butyrate resin Poly(amide-imide)... 

Polycarbonate acrylonitrile-butadiene-styrene alloy Allyl-diglycol- carbonate polymer Diallyl phthalate molding Cellulose acetate Cellulose-acetate-butyrate resin... 

Gun Propellents. Low sensitivity gun propeUants, often referred to as LOVA (low vulnerabUity ammunition), use RDX or HMX as the principal energy components, and desensitizing binders such as ceUulose acetate butyrate or thermoplastic elastomers (TPE) including poly acetal—polyurethane block copolymers, polystyrene—polyacrjiate copolymers, and glycidyl azide polymers (GAP) to provide the required mechanical... 

Semipermeable membrane coating (celluose acetate butyrate)... 

Other. 2-Nitro-1-butanol is an excellent solvent for many polyamide resins, cellulose acetate butyrate, and ethylceUulose. It can be utilized in paint removers for epoxy-based coatings. 2-Hydroxymethyl-2-nitro-l,3-propanediol is usebil for control of odors in chemical toilets. Its slow release of formaldehyde ensures prolonged action to control odor, and there is no reodorant problem which sometimes is associated with the use of free formaldehyde. 2-Hydroxymethyl-2-nitro-l,3-propanediol solutions are effective preservative and embalming fluids. The slow Uberation of formaldehyde permits thorough penetration of the tissues before hardening. 

Butyric acid, the simple oxidation product of -butyraldehyde, is used chiedy in the production of cellulose acetate butyrate [9004-36-8]. Sheets of cellulose acetate butyrate are used for thermoformed sign faces, bUster packaging, goggles, and face shields. 

Cellulose acetate [9004-35-7], prepared by reaction of cellulose with acetic anhydride, acetic acid, and sulfuric acid, is spun into acetate rayon fibers by dissolving it in acetone and spinning the solution into a column of warm air that evaporates the acetone. Cellulose acetate is also shaped into a variety of plastic products, and its solutions are used as coating dopes. Cellulose acetate butyrate [9004-36-8], made from cellulose, acetic anhydride, and butyric anhydride in the presence of sulfuric acid, is a shock-resistant plastic. 

Also produces cellulose acetate butyrate (CAB) and cellulose acetate propionate (CAP) mixed esters. 

Fig. 5. Composition of cellulose acetate butyrate (propionate) as a function of butyryl (propionyl) content of esterification bath.

Mixed esters containing the dicarboxylate moiety, eg, cellulose acetate phthalate, are usually prepared from the partially hydroly2ed lower aUphatic acid ester of cellulose in acetic acid solvent by using the corresponding dicarboxyhc acid anhydride and a basic catalyst such as sodium acetate (41,42). Cellulose acetate succinate and cellulose acetate butyrate succinate are manufactured by similar methods as described in reference 43. 

From 1946 to mid-1987, Farbenfabriken Bayer AG in Germany was the European producer of cellulose acetate, cellulose acetate butyrate (CAB), and cellulose acetate propionate (CAP) before closing its faciUties. Bayer s exit from the cellulose acetate mixed esters business leaves Eastman Chemical Co. in the United States as the sole producer of CAB/CAP resins. 

The cellulose esters with the largest commercial consumption are cellulose acetate, including cellulose triacetate, cellulose acetate butyrate, and cellulose acetate propionate. Cellulose acetate is used in textile fibers, plastics, film, sheeting, and lacquers. The cellulose acetate used for photographic film base is almost exclusively triacetate some triacetate is also used for textile fibers because of its crystalline and heat-setting characteristics. The critical properties of cellulose acetate as related to appHcation are given in Table 10. 

Table 11. Application and Characteristics of Commercial-Grade Cellulose Acetate Butyrate ...

Acetyl, % Butyryl, % Hydioxyl, % Acetate Butyrate Hydroxyl AppHcation... 

Cellulose acetate butyrates with high butyryl content and low viscosity are soluble in inexpensive lacquer solvents. They are widely used in lacquers for protective and decorative coatings appHed to automobiles and wood furniture. 

An alcohol-soluble cellulose acetate butyrate containing ca 50% butyryl and ca 4.5% hydroxyls available commercially. 

Low viscosity cellulose propionate butyrate esters containing 3—5% butyryl, 40—50% propionyl, and 2—3% hydroxyl groups have excellent compatibihty with oil-modified alkyd resins (qv) and are used in wood furniture coatings (155). Acetate butyrate esters have been used in such varied apphcations as hot-melt adhesive formulations (156), electrostatically spray-coated powders for fusible, non-cratering coatings on metal surfaces (157—159), contact lenses (qv) with improved oxygen permeabiUty and excellent wear characteristics (160—162), and as reverse-osmosis membranes for desalination of water (163). 

Cellulose esters, especially acetate propionate and acetate butyrate mixed esters, have found limited use in a wide variety of specialty appHcations such as in nonfogging optical sheeting (171), low profile additives to improve the surface characteristics of sheet-molding (SMC) compounds and hulk-molding (BMC) compounds (172,173), and controlled dmg release via encapsulation (174). 

Mixed esters such as cellulose acetate sulfate [51910-28-2] (21,22), cellulose acetate butyrate sulfate [57485-48-0] (21,22), cellulose acetate propionate sulfate [67351-39-7] (23), and ethylceUulose sulfate (24) are described in the patent Hterature but are not of commercial importance. 

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