Anionic emulsifiers

P perApplications. In beater additions, the latex is mixed with the beaten paper pulp either by addition at the beater or to the stock chest at the wet end of the paper machine. In either case, the pH of the pulp is reduced to 4.0—4.5, usually by the addition of a solution of alum to the pulp—latex mixture which has been thoroughly agitated. The latex, which for this appHcation must be based on an anionic emulsifier, coagulates as the pH drops. The latex soHds separate ia intimate associatioa with the pulp fibers. The pulp is thea screeaed and the paper web formed ia the coaveatioaal way. A latex for this purpose must possess the proper balance between mechanical and chemical stabiHty. 

Anionic emulsifiers, such as alkali salts of fatty acids, can be applied in anionic latices. Are particularly important as wetting and foaming agents in latex technology. Poly(glycol) ethers act as nonionogenic emulsifiers. 

From the various emulsifiers examined, an anionic emulsifier from the sulphonic acid group of polyglycol-ether of fatty alcohol and alkylphenol-polyglycol esters was used. The best results were achieved with the use of alkylphenol-polyglycol ester (Berol EMU27). 

Anionic complexes, tungsten, 25 386-387 Anionic copolymerization, 7 624-626 block copolymers, 7 645 Anionic emulsifiers, in VDC emulsion polymerization, 25 722 Anionic extractants, 10 750 Anionic flotation, 24 497 Anionic gels, 9 59-60... 

Conventional anionic emulsifiers are alkyl sulfates, alkyl sulfonates, aralkyl sulfonates, soaps of saturated or unsaturated fatty acids and alkaline disproportionated or hydrogenated abietic or tall oil acids (14). 

On the other hand addition of anionic emulsifiers, such as American Cyanamid Aerosol OT sodium dioctyl sulfosuccinate or Proctor Gamble Ivory Soap Flakes, markedly decreased volume resistitity. Thus, it seems that an impurity will con-... 

The latex was cleaned by ion exchange and serum replacement, which gave the cleaned latex plus six serum fractions. The cleaned latex and the serum samples were analyzed by conductometric titration. Also, the amount of anionic emulsifier in the serum was determined by Fyamine 1622 colorimetric titration and thin-film chromatography, and the amount of nonionic emulsifier by iodine-iodide colorimetric titration and thin-film chromatography. 

Thus these characterization results not only give the distribution of the acrylic acid between the aqueous serum, particle surface, and particle interior, but also account satisfactorily for the total number of strong-acid groups arising from the anionic emulsifier and initiator. In addition, both the sodium lauryl ether sulfate and the nonylphenol polyoxyethylene adduct used in the polymerization were recovered from the fractions obtained by serum replacement. 

Emulsifiable Calcium and amine salts of Anionic emulsifiers for... 

The small amount of acrylic acid is required to ensure freeze/thaw stability of the latex at a pH of 7 or higher and contributes to its mechanical stability. The anionic emulsifier (Fenopon SF 78) regulates the particle size and contributes to the stability of the system during latex preparation. The nonionic emulsifier (Tergitol NP 40) is required to obtain sufficient electrolyte stability and contributes to the mechanical and the freeze/thaw stability of the latex. Borax is used as a neutralizing agent. 

The distribution ratio of the anionic emulsifier, however, greatly affected the particle size, as illustrated in Figure 2. It was practically unaffected as long as more than about 15% of the anionic emulsifier was in the initial reactor charge. A further reduction of this amount, however, led to a steep increase in particle size. 

Figure 2. Influence of distribution of anionic emulsifier on average particle size...

To gain a better understanding of this phenomenon we followed the number of particles in the reactor with time during the monomer emulsion addition for three different distribution ratios of the anionic emulsifier. The ratios 40/60, 97/3, and 100/0 were chosen because they gave different particle sizes of the ultimate latex the first on the flat part of the curve in Figure 2, the second just in the bend, and the third on the... 

Figure 3. Number of particles during the addition period for different partitions of the anionic emulsifier...

The results of these experiments are depicted in Figure 3. They show that the number of particles formed in the initial stages of the latex preparation depends on the amount of anionic emulsifier present. When this amount was small, few particles were formed, and their number remained constant during further latex preparation. Thus, after initial particle formation, only a growth of existing particles took place. 

When a large amount of anionic emulsifier was initially present in the reactor, many particles were formed. This number decreased during the latex preparation because not enough emulsifier was added with the monomer feed emulsion to keep the surface of the particles covered. Controlled agglomeration of polymer particles occurred to a stage where... 

In actual fact, under these conditions the average particle size of the latexes was readily reproducible, but poorly so when less than 15% of the anionic emulsifier was present in the initial reactor charge. This can be understood by realizing that the number of particles formed initially cannot be very reproducible. Small variations in the induction period, for instance, will aflFect this number considerably because anionic emulsifier is added with the monomer feed emulsion. 

Figure 4. Influence of total amount of anionic emulsifier on average particle size at a constant 40/60 distribution over monomer feed emulsion and initial reactor charge...

The particle size distribution of various latices, prepared via the above monomer emulsion addition technique, was determined with the aid of an ultracentrifuge. It was found to be invariably of the log-normal type, as shown in Figure 6, independent of the way the particles are formed. This illustrates that the agglomeration of particles during latex preparation, when the initial reactor charge contained more than 15% of the anionic emulsifier, is a random and not a selective process. 

Vinyl esters of trialkylacetic acid copolymerize randomly with vinyl acetate. Paint latices with a very low residual monomer content, based on vinyl acetate-W 911 copolymers, can be prepared reproducibly via a variant of the monomer emulsion addition technique, when a relatively large part of the anionic emulsifier is present in the initial reactor charge. 

Is a water-soluble emulsifier for solvents and oils. It is a lubricant and softener for textiles and leather. It also acts as a versatile co-emulsifier with anionic emulsifiers in formulating textile dye carriers based on aromatic and aliphatic solvents. 

INTEX SCOUR 171 is a blend of solvent with an anionic emulsifier, so that the product disperses with no difficulty in water. 

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