Resin emulsion

In practice, the taffy process is generally employed for only medium molecular-weight resins (1) (n = 1-4). The polymerization reaction results in a highly viscous product (emulsion of water and resin) and the condensation reaction becomes dependent on agitation. At the completion of the reaction, the heterogeneous mixture consists of an alkaline brine solution and a water—resin emulsion and recovery of the product is accompHshed by separation of phases, washing of the taffy resin with water, and removal of water under vacuum. 

Epoxy resin emulsions are commercially available from several sources. As a group, the typical particle size of the dispersion is in the 0.5- to 3.0-pm range. Solids typically range from 50 to 65 percent, and viscosity from 10,000 to 12,000 cP. The dispersions, in general, are thixotropic as supplied. There is also a dramatic decrease in viscosity of the system with the addition of water. Table 4.7 shows the effect of dilution and Brookfield viscosity spindle speed (thixotropy) on a typical epoxy emulsion. 

Both processes are applicable to waterborne epoxy adhesives and coatings, although the emulsification process is generally used with adhesives. Preparation of epoxy resin emulsions is covered in Chap. 4. 

Table 14.4 presents formulation information for bisphenol A and polyfunctional epoxy resin emulsions that are cured with an aliphatic amidoamine curing agent. Adhesive performance data are also provided for substrates common to the automotive industry. Both formulas are based on a 1 1 epoxy-amine stoichiometry and they are reduced to 45 percent nonvolatiles with water. The working life of each system is several hours at room temperature. 

Similar information is presented in Table 14.5 for starting adhesive formulations made from an epoxy resin emulsion and dicyandiamide latent curing agent. This adhesive has exceptionally good water resistance when cured. The adhesive was applied to the indicated substrates in a manner similar to that described above, and it was cured for 3 min at 65°C followed by 10 min at 175°C. 

DGEBA epoxy resin (EPON 828, Resolution Performance Products) Epoxy resin emulsion (EPI-REZ WD-510, Resolution 100 100... 

H. Warson, The Applications of Synthetic Resin Emulsions, Ernest Beim Ltd., London, 1972. 

Warson, H., "Synthetic Resin Emulsions", Benn, London, 1972. 

Chemical nature Reactive resinous emulsion Appearance Free-flowing, off-white emulsion Solubility Dispersible in water at any concentration Density 8.6 pounds per gallon... 

A silicone resin emulsion product designed to impart durable water repellency when suitably applied and cured to various fabrics. The recommended CATALYST SL Cone, to be used in the application of RANEOFF S. 

Is a textile printing lubricant supplied as a nonionic emulsion and used to provide excellent lubricity for pigment prints in machine printing. This product is especially effective with acrylic resins and other synthetic resin emulsion bonding systems... 

This low crock is a modified organic resin emulsion designed to give excellent binder properties and is used in an aqueous pigment printing system. 

Is a very hydrophilic emulsifier used for preparing solubilized oils. It is also used as a viscosity modifier and as a softener or plasticizer in acrylic or vinyl resin emulsions,... 

Silicone resin emulsion for water-repellent finishes. 

Silicone resin emulsions. With the aid of suitable emulsifiers and stabilisers, insoluble silicone resins can be converted into water-soluble emulsions and can be diluted with water. Such emulsions are used as water-repellent additives for plaster or silicate emulsion paints as well as for the surface treatment of mineral powders such as perlite, aerated concrete granules, and so on. 

It is well known that organosilicon compounds do not become equally well attached to all mineral substrates. While silicates always readily lend themselves to coating with silane and polysiloxane [19-21], the same cannot always be said of calcium carbonate [19, 20]. Calcium carbonate (calcite), a widely used filler, is generally considered difficult to cover with silanes. Given the proven, good attachment of silicone resin to calcium carbonate fillers in silicone resin emulsion paints [2, 22], the question arises as to whether only higher polymeric siloxanes are able to form hydrophobic protective coatings on calcium carbonate. 

The fact that mineral-paint-like silicone resin emulsion paints, which have veiy open pores yet... 

The binders used for silicone resin emulsion paints [16] are almost exclusively methylsilicone resins, R-SiOsa (R = CH3), in combination with an organic polymer binder. Aqueous silicone resin emulsions predominate. As a solvent-free solution cannot be produced from a solid resin, high-viscosity silanes/siloxanes/silicone resin mixtures are used that differ initially from the solid resin in the degree of polymerization. 

The paint samples were prepared from a high-grade silicone resin emulsion paint [48] with a binder ratio of 10 wt% styrene acrylate to 10 wt% silicone resin emulsion (both 50% solids). The coatings were applied to a mineral substrate and dried at room temperature. Part of each sample was etched for a few minutes in 10% nitric acid so that the organic polymer could be visualized better. 

Silicone resin emulsion paints always contain two binders, i.e. some of the organic polymer binder in the emulsion paint is replaced by silicone resin. Silicone resin emulsion paints are predominantly formulated at high PVC (pigment volume concentration > 60%), as a result of which the overall binder content is low. The PVC is a theoretical description of the volume fraction of the... 

Theory Behind Silicone Resin Emulsion Paint... 

Fig. 2. Highly simplified model of the microstructure of a silicone resin emulsion paint.

The microstructure of a silicone resin emulsion paint is shown in Fig. 3. The overview even at low magnification (Fig. 3a) indicates that one binder forms thick films (black arrows) into which sinks some of the approx. 300-nm-sized white pigment (titanium dioxide). This is the organic polymeric binder. Because of the deficit of organic polymer, pore voids are open and voids between fillers are only partly filled (Fig. 3c), i.e., only small adhesive bridges are present (black arrows in Figs. 3a,c), which determine the binding power. 

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