Latexes formulation

Chemically related database searches can be used to estabhsh concepts and patentable ideas. For instance, searches have identified researchers using particular monomers in a potentially patentable latex formulation found precedents for a polymeric emulsifier summarized pubHcations of people being considered as consultants, expert witnesses, employees or speakers to an industrial group and provided market description information for a new pigment manufacturing firm to identify target markets. 

Metal oxides. Zinc oxide is the most effective metal oxide. The zinc oxide should have a low lead content. Zinc oxide has three main functions (a) promote cure (b) improves ageing, heat and weathering resistance (c) acid acceptor. In general, 2-5 phr zinc oxide is added in latex formulations. 

Antioxidants. Similar antioxidants as for solvent-borne CR adhesives can be used. Addition of antioxidants is important when resins sensitive to oxidation are included in polychloroprene latex formulations. 2 phr is the common amount of antioxidant in latex adhesives. 

Fillers. Addition of fillers is not common in polychloroprene latex formulations. Fillers are used to reduce cost and control rheology, solids content and modulus. However, cohesion and adhesion are reduced. Calcium carbonate, clay and silica are some of the fillers than can be added. Alumina trihydrate is often used when resistance to degradation by flame is important. 

Other ingredients. Bacterial and fungal attack can be a problem in poly-chloroprene latex formulations with pH below 10. It is manifested by odour, discolouration and gas evolution 500-1500 ppm of a biocide should be added. 

It has to be kept in mind that the polymer properties desired in polychloroprene latex formulations may be totally different from those needed in dry grades. Polychloroprene latices generally exhibit lower contactability than dry polychloro-prenes because of the presence of residual soaps and salts, appreciable gel content and segregation of tackifier [79]. For this reason, the polychloroprene latices have usually medium to low crystallinity. 

Additives in the latex formulations such as emulsifier etc. absorb in the UV range. 

Nonwoven products ranging from medical disposables to automotive fabrics are required to meet specific flammability standards. These fabrics are generally composed of cellulosic and/or synthetic fibers which are flammable. Additionally, polymer coatings are applied to the fabric to impart properties such as strength, abrasion resistance and overall binding. It is the purpose of this paper to describe the various polymer coatings commonly used in the nonwovens industry and their effect on flammability of the substrates. Additionally, the effect of flame retardant additives, commonly used in latex formulations, will be discussed. 

Effect of silanes on adhesion strength of latex formulations... 

While most studies of particle swelling have dealt with emulsion polymers containing high acid levels, we have restricted our attention to latexes containing relatively low incorporated acid (ca.2-3%) to avoid substantial solubilization of the particles. Questions under current consideration are related to the location of incorporated carboxyl groups within the latex particles, the morphology of expanded particles, and the detailed mechanism of expansion. Information of this type is valuable not only from a fundamental standpoint but is essential in the investigation of very practical problems such as the viscosity stability of latex formulations. 

Water is sometimes used as a solvent for water-soluble resins. Certain epoxy adhesives are available as water-based emulsion or latex formulations. In the early 1970s, during the time of the petroleum crisis, water-based adhesives were thought of as a possible replacement for solvent-based adhesives systems. However, water-based adhesives never met the lofty expectations primarily because of the time and energy required to remove water from the bond line, the corrosion that the water causes in drying ovens, and the poor moisture resistance of cured water-based adhesives. 

Pale yellow gel. Can be added directly to latex formulations if good compounding equipment is available but generally it is prediluted with 2 parts water in a low shear mixer. 

To determine the nature of the silicon moieties in a polymer, clearly the easiest method would be a technique that provides a direct observation of the silicon atom and meaningful, interpretable information on the atom. Nuclear magnetic resonance spectroscopy tuned to the Si isotope ( Si NMR) is a tool of this nature it can directly probe the state of the silicon atom, and with it one can often readily determine the extent to which Si-O-Si crosslinks (fi-om silanol condensation), have formed. One can observe spectra of silicon-containing compounds either dissolved in a solvent or in the solid state. Liquid-state Si NMR, while the most sensitive, cannot be used quantitatively on heterogeneous systems such a latex formulations. Therefore, one must separate the liquid and solid portions of the latex (without heat, which would promote hydrolysis and condensation) and use the solid residue for the Si NMR experiments. 

Mixed emulsifiers are commonly used in combination with electrolytes to attain oil/water interfacial tensions substantially less than 1 dyne/cm, eg. 10 1 to 10 dynes/cm (31). The stability of the resulting microemulsions is usually attributed to the formation of an interfacial film (32,33). Even though the mechanism of stabilization has not yet been resolved, the excess surfactant used in microemulsions usually assures good stability. However, due to the very low mixed emulsifier concentrations used in miniemulsions, an understanding of the interactions between mixed emulsifier molecules at oil/water interfaces should greatly facilitate the development of miniemulsion and mini-latex formulations to achieve good stability. 

This entry describes some common polymers used in latex formulations and standard synthesis methods. Particle interactions and reasons for the loss of stability will be reviewed and mechanisms of film formation will be outlined. 

Incorporation of aqueous dispersions of antimony pentoxide into latex requires a pH adjustment prior to adding it to latex to prevent latex coagulation. Dispersions of antimony pentoxide usually have a pH = 5 which is too low for use in most latex formulations. Adjustment of pH can be made with ammonia but prior to such a pH adjustment it is necessary to dilute the dispersion to a concentration below 40% SbzOs. 

Magnum-White. [RMc Minerals] Magnesium hydroxide/calcium carbonate blend fire retardant smoke suppressant filler for PVC compds., SBR-latex formulations. 

The studies just discussed do not address one of the significant contributions associative thickeners make to coatings rheology minimizing LSVs in small-particle latex formulations. 

There are several formulation components that can be present in an emulsion polymer (latex) formulation, which can be added before, during, or after the polymerization reaction. This section is intended to provide the reader with an overview on the role of each component, as well as their in impact the process and/or the product. 

The monomer, sodium styrene sulfonate (NaSS), can be included in a latex formulation to incorporate a strongly bound, acidic sulfonate group into the latex. The use of persulfate initiator will result in the incorporation of bound sulfate end-groups into the polymer chain however, these groups can become hydrolyzed... 

In addition, allyl methacrylate is often added to a latex formulation as a crosslinking/grafting monomer [52] especially in the case of core-shell latexes. This monomer is often used to promote adhesion between various polymeric layers, especially in multilayered composite latex particles, which are often used as impact modifiers [53]. 

Chain transfer agents (CTA) are added to a latex formulation to help regulate (i.e., decrease) the molar mass and molar mass distribution of the latex polymer. The extent of chain transfer can be predicted, if the chain transfer constants (Cs) are known for a given monomer system. Riddle [114] presents a table summarizing some of the chain transfer constants for methyl methacrylate with a wide variety... 

In practical latex formulations, the latex particle size can play a major role in determining the rheology obtained with a given associative thickener. A thickener which provides nearly Newtonian flow with a large particle size, relatively hydrophilic latex (such as an interior paint grade vinyl-aciylic latex) may produce veiy high low-shear viscosity, and shear thinning when a smaller particle size, more hydrophobic acrylic latex is used in the same formulation. 

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