Addition of Polyols

Polyols derived from e-caprolactone can be used as reactive diluents to enhance both application solids and performance of hydroxy/acrylic melamine enamels. These polyols (Tone from Union Carbide and Capa from Interox) have the following features  

The replacement of 30% hydroxy acrylic by the caprolactone based polyols in one system gave an increase in volume solids content at spray viscosity of 5%, better impact resistance and greatly improved gloss after 1000 hours exposure to the QUV Weatherometer. 

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An entirely different class of poly(ortho esters) has also been described (11). These polymers are prepared by the addition of polyols to diketene acetals. Principally due to the relative ease of... 

It was found that PU s became nonflammable in air with the addition of polyol with phosphorous. 

Figure 5 shows TG curves for PU with 0-8% of polyol containing phosphorous. The starting temperature of degradation of PU decreases with increasing the amounts of added polyol with phosphorous. This indicates that the addition of polyol with phosphorous reduces thermal stability of PU. However, it can be said that the retardation of degradation is promoted by the addition of polyol containing phosphorous at temperatures over approximately 400° C. 

Using controlled reaction conditions such as the temperature profile and rate and time of the addition of polyols, more uniform materials can be produced. The correct spacing of the hard segments required to produce the physical properties can be obtained. The controlled conditions will also help prevent the formation of undesirable side products such as allophanate, biuret, and trimers. These reactions will give branching of the polymer chains. 

If a pump is fitted to the discharge of the reactor, it can be used to fast-circulate the hot prepolymer through cooling tubes to rapidly reduce the temperature. When the temperature probes indicate a too-rapid temperature rise, the addition of polyol must be slowed down immediately. If the temperature still rises too quickly, the addition of the polyol must be stopped until the temperature is brought back under control. The temperature probes must be positioned so that the temperature of the prepolymer indicated is unaffected by the wall temperature of the reactor. A second thermocouple positioned elsewhere in the reactor can be used to detect runaway reactions. 

It is almost always desirable to have a homogenous enzyme formulation, that is, without precipitations. Unwanted crystallization in the liquid formulation of the enzyme can occur if the enzyme concentration, pH, ion strength, etc. are in the right range. This can be avoided by addition of polyols and adjustment of pH. Impurities remaining from the fermentation broth may also precipitate and can, to a certain degree, be handled by adjustment of the formulation. However, it is generally more optimal to solve these issues upstream in the production process, that is, in the fermentation or primary separation steps. 

Further effort resulted in the development of a second major famUy of POE polymers based on the addition of polyols to diketene acetals (HeUer et al, 1980), prepared by the procedure shown in Scheme n. 

Polyurethanes are manufactured by addition of polyols (polyether or polyester) with polyvalent isocyanates. Polyether-polyols are sensitive to oxygen. Thermal-oxidative degradation typically occurs during the manufacture of flexible foams when water is used to form carbon dioxide as blowing agent. Large PUR slab stock... 

A second family of polyorthoesters, derived from the addition of polyols to di-ketene acetals without forming condensation by-products, was developed by SRI International (Scheme 4B). Initial work was conducted with the monomer, diketene acetal (3,9-bis(ethylidene-2,4,8,10-tetraoxaspiro[5,5]undecane, DETOSU), derived from pentaerythritol and 1,6-hexane diol. This reaction is exothermic and proceeds to completion virtually instantaneously. Then, the diketene acetal is reacted with a polyol to synthesize the polyorthoester. Here, the hydrolytic products are the diol and pentaerythritol dipropionate the further hydrolysis of this latter compound produces propionic acid, but no autocatalytic reaction is observed because this hydrolysis proceeds much more slowly than that of orthoester bonds. 

Polyurethanes are prepared by the addition of polyols to polyfunctional isocyanates. 

Sagitani has described an alternative method for producing fine 0/W emulsions called surfactant-phase emulsification . Here, the addition of polyols like 1,3-butanediol to the usual emulsion components oil, water and surfactant is necessary. In the method, oil is added dropwise to an isotropic solution of concentrated surfactant in a water/polyol mixture. A clear gel eventually forms which is an oil-... 

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