Binders deflocculation

Acryhc modifiers for cement impact strength and adhesion to substrates are discussed in reference 211. Both water-soluble acryhc and acryhc emulsion polymers are used in the ceramic industry as temporary binders, deflocculants, and additive components in ceramic bodies and glazes (212) (see Ceramcs). 

Acrylics have been nsed to impart impact strength and better substrate adhesion to cement (228). The ceramics indnstry uses both acrylic solution and emulsion pol5nners as temporary binders, deflocculants, and additives in ceramics bodies and glazes (229) (see Ceramics). 

Forming additives or processing aids (2,33—37) are commonly used to render ceramic powders more processible. Binders and plasticizers (qv) are typically added to improve or aid dry powder and plastic forming, whereas deflocculants, surfactants (qv), and antifoams are commonly used in slurry processing. 

Additives serve a variety of functions in forming , which may be divided into four categories binders, plasticizers, dispersants (also referred to as deflocculants), and lubricants. 

Use Stabilization of asphalt emulsions, ceramic binder and deflocculant, dye leveler and dispersant, drilling-fluid additive, precipitation of proteins, extender for phenolic plastics, special molded products, source of vanillin, phenol, and of a component of battery expanders. 

Material Solvent Deflocculant Binder Plasticizer Viscosity (mPa-s) Ref. 

Adhesives, binders, and deflocculants function is dependent primarily on the presence of polysilicate ions. The soluble silicate used has a ratio range of 2.5 to 4.0, where the ratio is defined as one-half of the ratio of moles of Si to moles of cation (e.g., Na+ or tetramethylammonium ion, TMA+). 

Features High mol. wt. polymeric wide compat. range from NC-systems to long oil alkyd systems strong resist, to binder and solvent shock long-term deflocculation stability high color str. 

According to their functions, the additives in ceramic process can be classified into four main groups (i) solvents, (ii) dispersants, also known as deflocculants, (iii) binders, and (iv) plasticizers. Additives with other functions, such as lubricants and wetting agents, are also used in some occasions. Successful additives have often been found by trial-and-error approaches, although information is available on chemical principles and applications of additives [71, 72]. 

A deflocculant is an additive that works in the system to keep particles apart. The role of a deflocculant in a tape casting slip is fivefold (1) to separate or hold separate the primary particles so the binder can coat them individually, (2) to increase solids loading in the powder suspension in order to maintain moderate viscosities after binder addition, (3) to decrease the amount of solvent in the powder suspension in order to save money on solvents, (4) to decrease the amount of solvent in the powder suspension in order to dry the slip faster and with less shrinkage, (5) to burn out cleanly prior to sintering in order not to contaminate the final fired part. 

That, after all, is the bottom line as it pertains to the defloccu-lant/dispersant. The purpose of dispersion and deflocculation— breaking apart the particles, wetting the particles, holding a fluid layer between primary particles, and whatever else goes on in the dispersion mill—is to prepare the particles to meet the binder and behave in a beneficial manner while the binder does its work. The separation of particles is to allow the binder to attach to each particle separately instead of surrounding groups of particles. Many, many additives exist that can fulfill this need for separation. Literally hundreds of chemicals have been looked at for this purpose over the years. While we have only looked in depth at two of these additives, some of the referenced works list many others to try. b47,52,58,59... 

One study of this interaction that we performed involved the use of polyvinyl butyral and two different dispersants, menhaden fish oil and phosphate ester. Batches were charged identically, with the exception of the dispersant. One batch was formulated with 4 wt% menhaden fish oil per powder weight, while the other was formulated with 2 wt% phosphate ester per powder weight. After dispersion milling, the MFO batch was very viscous, almost a paste (>20,000 cP), while the phosphate ester batch was extremely fluid (<100 cP). After identical plasticizer and binder additions, the slips were measured to have identical viscosities (approximately 2500 cP). In the MFO batch, the binder s dispersing action far overshadowed the fluidizing action of the MFO. Conversely, the phosphate ester was seen to be a much better dispersant/deflocculant than the MFO. The tapes cast from these slips were nominally identical, as were the fired densities and yields. 

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