Amine Activation of 5°C. Emulsion Copolymerizations

Abstract

T h e discovery that polyamines were effective reducers for the hydroperoxide initiator system of cold rubber prompted a further study in the preparation of butadienestyrene copolymers and an attempt to apply them to the preparation of butadiene-acrylonitrile copolymers.In the preparation of butadiene-styrene copolymers a mixture of polyamines composed of 80% diethylenetriamine and 20% tetraethylenepentamine was found best for uniform rates of conversion. The rate of conversion could be adjusted by adding ferrous iron or an iron complexing agent. Similar amines were found to be ineffective activators in the copolymerization of butadiene and acrylonitrile. The reason appeared to be the cyanoethylation of the amines with loss of reducing power. This was prevented or slowed by the addition of digested D-glucose or other source of enediol to the amine solution, whereby a reducer was formed which was not destroyed by reaction with acrylonitrile. Such hydroperoxide-reducer systems are suitable for commercial use. The advantages appear to be ease of preparation of the activator, reduced sensitivity to oxygen, preparation of synthetic rubbers in the virtual absence of iron salts, and, for butadiene-styrene copolymers, preparation in the abssnce of the sugar which tends to ferment in the latex on standing.HE use of peroxy compounds and reducers as initiator sys-T tems for free radical polymerization reactions has been studied extensively for many yeam The use of amines as reducers has also received considerable study. One aspect of the work ( 8 ) is that in which a water-soluble amine is used with a water-soluble peroxy compound in emulsion polymerization, or an oil-soluble amine is used with an oil-soluble peroxy compound in bulk polymerization. Several papers have appeared describing amines as activators in redox polymerizations of butadiene and styrene of the type in which a water-soluble reducer is used in combination with an oil-soluble peroxy compound and usually with a heavy metal carrier such rm ferrous iron. (Ethylenedinitri1o)tetraacetic acid and other chelate-forming organic nitrogen compounds (19) were effective reducers (activatnrs) in the preAence of digested wglucose and ferrous sulfate. The ferrous sulfate could be reduced in quantity or eliminated entirely with practical rates of Conversion being achieved.A significant advance waa made by Whitby el al. (21) who observed that polyethylene polyamines were effective activators without digested -glucose or ferrous sulfate. The present authors (80) enlarged this study and indicated that ferrous sulfate and digested wglucose could play important roles in the activation of a commercial recipe using polyamines. Such recipes have been used by others (6, 19). Under optimal conditions the activators are simple to prepare, the solution need not be handled with exclusion of oxygen, and the resulting recipe appears to be less sensitive to oxygen contamination (6, 19, 21). The chief disadvantage appears to be extreme sensitivity to iron contamination; this effect can be...

The Role of Alpha-Ketols in the Low-Sugar Redox Recipe for Low Temperature Emulsion Copolymerization

“…That sugars may form a complex with iron has been indicated by several publications (3,4,25,55,56,57). On the other hand the digestion (10) of dextrose may result in many compounds such a s fructose, acids, and oxidation products (12).…”

“…The work of Ernbree et al (4) strongly suggests that sugars are also able to form complexes witli amiiles which conlplexes are still powerful reductants in tlie virtual absence of iron but are not destroyed by cyanoethylation reaction with acrylonitrile (4,64). T h a t aniines and sugars may form coniplexes has been indicated (34,40,45).…”

“…by the amount of ferrous sulphate used, the other ingredients remaining in equimolar ratio. Greater detail will be found in two earlier papers (41,42) and others from this laboratory (4,39,48 For personal use only.…”

“…These lists include many of the above conlpounds also. T h e use of anlines, sugars, and ferrous iron mixed has been shown to be a versatile and effective system (4,48).…”

Polymerization of GR-S at Low Temperatures

“…Just as the sugar-free, ferrous pyrophosphate recipe has been preferred in polymerizations where at least part of the emulsifier is rosin soap, polymerizations emulsified with all-fatty-acid soap at the present time employ a so-called polyamine activation system in place of ferrous pyrophosphate. The polyamine activators, first described by Whitby et al (17) and later studied extensively by other investigators (3,9), have been found to be very versatile, and the lack of necessity for complex activator preparations has resulted in excellent reproducibility of reaction rates. In polymerizations employing all-fatty-acid soap emulsification at 41°F.…”