Accelerator polyester resin

Uses Intermediate for paints, dyestuffs organic synthesis curing accelerator for unsat. polyester resins accelerator in food-contact crosslinked polyesters... 

Hazardous Decomp. Prods. Heated to decomp., emits acrid smoke and irritating fumes Uses Drier for paint, varnish, in food-contact coatings drier migrating from food pkg. adhesion promoter bonding rubber to steel and other metals catalyst accelerator in unsat. polyester resins accelerator in food-contact crosslinked polyesters Regulatory FDA 21CFR 175.300, 177.2420, 181.25... 

Cobalt chloride, 1% petrolatum (polyester resin accelerator)... 

Cobalt salts are used as activators for catalysts, fuel cells (qv), and batteries. Thermal decomposition of cobalt oxalate is used in the production of cobalt powder. Cobalt compounds have been used as selective absorbers for oxygen, in electrostatographic toners, as fluoridating agents, and in molecular sieves. Cobalt ethyUiexanoate and cobalt naphthenate are used as accelerators with methyl ethyl ketone peroxide for the room temperature cure of polyester resins. 

An interest has been developed in the use of vanadium naphthenates as accelerators. In 1956 the author found that if MEKP was added to a polyester resin containing vanadium naphthenate the resin set almost immediately, that is, while the peroxide was still being stirred in. Whereas this effect was quite reproducible with the sample of naphthenate used, subsequent workers have not always obtained the same result. It would thus appear that the curing characteristics are very dependent on the particular grade of resin and of vanadium naphthenate used. It was also observed by the author that the gelation rate did not always increase with increased temperature or accelerator concentration and in some instances there was a retardation. Subsequent workers have found that whilst the behaviour of the naphthenate varies according to such factors as the resin and catalyst used, certain vanadium systems are of value where a high productivity in hand lay-up techniques is desired. 

As small molecule fragments resulting from the initiator may plasticize the polymer and lower performance, approaches have been developed to avoid this. A dihydroxyamine can be used to form a polyester [52]. This accelerator gave a modest increase in the strength of unsaturated polyester resins. A polymerizable tertiary amine has been prepared by the reaction of A-methylaniline with glycidyl methacrylate [53] (Scheme 8). 

P.Y.97 is also used to lend color to cast epoxy resins and to unsaturated polyester resins it considerably accelerates the hardening process in the latter (Sec. 1.8.3.7). 

The binder itself (Genpol A-20 polyester resin, styrene and methyl acrylate) was combined with the necessary polymerization catalyst (methyl ethyl ketone peroxide) and an accelerator (cobalt octoate or naphthenate). 

Resin solidification (curing) occurs by a free radical addition mechanism at the double bonds. That is why no by-products are formed. Curing compositions based on polyester resins contain a large number of different components (resins, initiators, accelerators, monomers, oligomers, fillers, etc), which may have various chemical structures, and may be used in various proportions. 

Within certain restrictions, unsaturated polyester resins are made thermochromic by the addition of a methanolic Co(II) chloride solution. The unsaturated ester, CoCl2 solution, peroxide catalyst, and accelerator are combined, and the resulting composition is cured at low temperature. The cured resin is colorless at 10°C but deepens in color as the temperature rises, until a blue color is attained at 40° C. This color change is reversible however, the thermochromism is destroyed by heating to temperatures above 70°C [51]. 

Demmler, K. and Schlag, J. (1971) Accelerators for polyester resins. Journal Schlag, Farb und Lock, 77, 224. 

Use Manufacture of polyethylene, polypropylene, ethylene oxide, ethylene dichloride, ethylene glycols, aluminum alkyls, vinyl chloride, vinyl acetate, ethyl chloride, ethylene chlorohydrin, acetaldehyde, ethyl alcohol, polystyrene, styrene, polyvinyl chloride, SBR, polyester resins, trichloroethylene, etc. as a refrigerant, in welding and cutting of metals, an anesthetic, and in orchard sprays to accelerate fruit ripening. 

Secondary amines have been found to accelerate the air saturated photocuring of 1,6-hexanediol diacrylate resin" associated with the former giving alkylamino radicals which scavenge the oxygen. The photosensitivity of a series of polyester resins to an argon ion laser has been found to... 

Accelerator. [Akzo] Cobalt octoate mixtures accelerators for cure of unsat. polyester resins at R.T. and elevated temps. 

Indirect food additive—polyester resins, cross-linked solvents for inhibitors, accelerators, and catalysts... 

Two types of commercially available orthophthalate-type unsaturated polyester resins (UP) were used as liquid resins, together with a 55% DMP(dimethyl phthalate) solution of methyl ethyl ketone peroxide (MEKPO) as a catalyst and a 8% mineral turpentine of cobalt octoate (CoOc) as an accelerator. UP-2 containing CoOc accelerator of 0.75phr (parts per hundred parts of resin). The properties of the unsaturated polyester resins are listed in Table I. 

Fig. A shows the effects of CoOc and MEKPO contents on setting shrinkage of polyester resin concrete. The setting shrinkage increases with rising contents of CoOc and MEKPO. In particular, the shrinkage is remarkably affected by MEKPO (catalyst) content rather than CoOc (accelerator) content.

At 2 to 3 hours of the curing time, slight expansion of polyester resin concrete with 0.5 phr catalyst and 0.5 phr accelerator is attributed to the looseness of compaction due to the setting retardation of the concrete. 

The setting shrinkage of polyester resin concrete increases with a rise in contents of catalyst and accelerator, and is markedly affected by catalyst content rather than accelerator content. 

The industrial production of an unsaturated polyester resin is controlled by several factors, whose levels confer on it certain properties that are important to other industries that use the resin as raw material for making finished products. In the curing stage, a catalyst is added to accelerate gel formation by the resin. The time when the gel starts to form, after the catalyst is added, is an important characteristic known as gel time. 

Liquid polyester resins are often used at ambient temperatures, for applications such as glass fiber impregnation, for example, in the manufacture of boats, or for casting purposes. Curing is usually achieved by addition of peroxide initiator and accelerator immediately before use. Measurement of the time to gel, i.e., the time the operator has to impregnate the reinforcement or pour the castings, etc., is of particular relevance. 

The two most important peroxy materials used for room temperature curing of polyester resins are methyl ethyl ketone peroxide (MEKP) and cyclohexanone peroxide. These are used in conjunction with a cobalt compound such as a naphthenate, octoate, or other organic-solvent-soluble soap. The peroxides are referred to as catalysts (though, strictly speaking, these are polymerization initiators) and the cobalt compound is referred to as an accelerator. 

Amino Resins. Formaldehyde-modified amino resins (i.e., melamine, benzogua-namine, and urea resins) are the most important resins for the heat curing of hydroxyfunctional polyester resins. These resins are readily available with a low molecular mass (very good polyester compatibility, but less reactive) or in precondensed form (limited compatibility, but very reactive). In order to prevent premature reaction in the wet paint, the amino resins are blocked by etherification with, for example, methanol or butanol. Sulfonic acids (e.g., p-toluenesulfonic acid, dodecyl-benzenesulfonic acid) have proved suitable for accelerating the deblocking of amino resins during heat curing. These acids must also be used in blocked form (ammonium salts, thermolabile adducts). 

Catalysts also include accelerators for two-pack polyurethane paints (e.g., tin and zinc compounds, tertiary amines) and initiators for unsaturated polyester resins that act as radical-forming agents. 

The decomposition of initiators is induced by heat in the case of molding compounds or by accelerators at temperatures below the decomposition temperature of the initiator in the case of cast polyester resins. Two types of accelerators are used, metal salts—mainly cobalt salts—and amines. The oxidoreduction of metal salts by peroxides produces free radicals. The process is very efficient since both lower and higher valencies of cations participate in the reaction. 

Unsaturated polyester resins are mainly made by condensing a dibasic acid (1,2-propanediol) with an anhydride (maleic or phthalic anhydrides), by forming ester linkages between the dibasic acid (or their anhydrides) and glycols. Then a reactive monomer (mostly styrene or vinyl toluene, MMA or diallyl phthalate) is used to crosslink the system when needed. Unsaturated denotes the uncompleted chemical activity (double bond) in the original structure, which are used for crosslinking afterwards. In this context, an excess of styrene as the crosslinker (10 to 50 %) is usually added to have it ready in the system, as well as to reduce the viscosity. There are also certain accelerators used (such as, cobalt naphthenate or tertiary amines like dimethyl aniline) to facilitate the cure at ambient temperatures. In addition, there may be pigments, fillers, various inhibitors, accelerators, stabilisers and flame retardants, added to the system. Polymerisation is activated whenever a catalyst (i.e., benzoyl or methyl-ethyl-ketone peroxide) is added. 

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