Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-02-04
2001-07-17
Pezzuto, Helen L. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S319000, C526S329700
Reexamination Certificate
active
06262212
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a process for manufacturing salts of polymers of dimethylaminoethyl(meth)acrylate which is particularly useful as a foam booster in shampoos, body washes, detergent formulations for dish washing or laundry, and in oilfield uses.
BACKGROUND OF THE INVENTION
Detergent compositions, e.g. liquid detergents, are well known. Typical applications include dish washing detergents, hand cleansers, and shampoos. Liquid detergents in particular have met with a high degree of acceptance due to their good cleaning performance and convenience of use.
Many detergent compositions, such as liquid hand dish washing detergents are comprised of two fundamental components, i.e. a surfactant base and a foam booster. The surfactant base, which usually consists of on or more anionic and/or nonionic surfactants, is largely responsible for the foam profile of the composition, i.e. initial copious foam height, volume, and density, and cleaning performance.
Liquid dish washing detergents can contain types of surfactants which are known to be more effective at removing specific types of soils. For example, anionic surfactants are known for their utility to remove carbohydrate and protein soils, while nonionic surfactants are especially useful for removing greasy and oily food soils. Mixtures of surfactants are commonly used to clean and remove complex soils which can be found on dishes and kitchen utensils.
For many detergents, especially liquid dish washing detergents, performance is commonly evaluated by the consumer in terms of the foaming and foam stability produced by the detergent. The consumer associates better performance with the presence of higher levels of foam and by foam that persists for extended periods of time even when exposed to various food soils. Dish detergent compositions on the market are designed to remove oily/greasy soils form glasses, dishes and other tableware and kitchen utensils while maintaining an acceptable level of foam. Consequently, there is an ongoing effort to make detergent compositions that clean and foam better and produce a more stable foam.
Foam boosters, which are also known as foam stabilizers or suds enhancers, are commonly used to prolong the persistence of the foam head generated during the dish washing process. Hand dish detergents are expected to produce copious amounts of foam in the presence of various food soils. Foam boosters provide the abundant, long-lasting foam that consumers perceive as being directly proportional to detersive utility.
SUMMARY OF THE INVENTION
This invention relates to a process of manufacturing a polymer having units derived from a salt of dimethylaminoethyl(meth)acrylate comprising polymerizing monomers comprised of dimethylaminoethyl(meth)acrylate in water and in the presence of sufficient acid to form a solution having a pH of less than 6.
DETAILED DESCRIPTION OF THE INVENTION
The homopolymers and copolymers of the present invention are prepared by subjecting dimethylaminoethyl(meth)acrylate, and one or more optional comonomers, in water, and in the presence of sufficient acid to form a solution having a pH of less than 6, to polymerization. Thus, it is necessary to first make a mixture of dimethylaminoethyl(meth)acrylate, water and a sufficient acid to form a solution having a pH of less than 6. Because the unionized form of dimethylaminoethyl(meth)acrylate tends to hydrolyze in water, it is preferred to dissolve the acid in water first to form an aqueous acid solution and to then add neat dimethylaminoethyl(meth)acrylate to the aqueous acid solution. While it is possible to first mix the monomer with water and then adjust the pH of the solution with acid, such a process will entail some hydrolysis of the monomer which could have been avoided.
The acid used to neutralize the dimethylaminoethyl(meth)acrylate may be a strong mineral acid, e.g. hydrochloric acid, sulfuric acid, or phosphoric acid, or it may be an organic acid, e.g. acetic or citric.
The amount of the acid used to neutralize the dimethylaminoethyl(meth)acrylate should be sufficient to produce an aqueous solution has a pH of less than 6, typically less than about 5.9, more typically less than about 5.8, and most typically less than about 5.7. Preferably, the pH of the solution will be less than about 5.5 and will preferably range from about 5.0 to about 5.5. The pH of the polymerization medium should be maintained at said pHs while there are significant amounts of the monomer present in the medium. In general, the acid will be added to the dimethylaminoethyl(meth)acrylate in a stoichiometric amount based on the molar amount of the acid. The control of pH avoids unnecessary loss of monomer as a result of hydrolysis thereof.
The weight ratio of dimethylaminoethyl(meth)acrylate monomer to citric acid will typically range from about 1:1 to about 2:1, more typically form about 1.3:1 to about 1.7:1, and most typically from about 1.4:1 to about 1.6:1. The amount of the monomer plus counter-ion in the polymerization medium will typically range from about 30% about 60%, more typically from about 35% to about 55%, and most typically from about 40% to about 50%.
A variety of comonomers can be used such as vinyl pyrrolidone, acrylamide, acrylic acid, vinyl acetate, methacrylic acid, acrylamidomethylpropanesulfonic acid, ethylenically unsaturated polyalkyleneoxy compounds (i.e. polymerizable surfactants such as “surfmers” such as polyoxyethylene(meth)acrylates and vinyl-benzyl ethers of polyalkoxylated fatty alcohols), and many cationic monomers (e.g. dimethylaminopropyl(meth)acrylamide and its methyl chloride/methyl sulfate quaternary versions) and mixtures thereof. Thus a variety of new polymers can be being made as illustrated immediately below.
The polymerization reaction is conducted in an oxygen-free environment, such as in the presence of an inert gas (e.g., helium, argon and the like), or nitrogen or with heating to drive off dissolved oxygen. The polymerization is carried out in an aqueous solvent, preferably water which is essentially free of organic solvents, e.g. lower alkanols such as methanol or ethanol. When essentially pure water is used as a solvent, the product will be essentially free of volatile organic compounds without the need to strip such compounds from the product.
Polymerization is initiated by making a mixture which comprises the aqueous solution of dimethylaminoethyl(meth)acrylate monomer and acid and a polymerization initiator. The initiators utilized are the usual free radical initiators. Examples include organic peresters (e.g., t-butyl peroxypivalate, t-amyl peroxypivalate, t-butyl peroxy- a-ethylhexanoate, and the like); organic azo compounds (e.g. azobisamidinopropanehydrochloride, azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, and the like); inorganic and organic peroxides (e.g., hydrogen peroxide, benzyl peroxide, and butyl peroxide and the like), and redox imitators systems, e.g. those having oxidizing agents, such as persulfates (such as ammonium or alkali metal persulfate, and the like), chlorates and bromates (including inorganic or organic chlorates and/or bromates), reducing agents, such as sulfites and bisulfites (including inorganic and/or organic sulfites or bisulfites) oxalic acid, and ascorbic acid, and combinations thereof. The preferred initiators are water soluble. The most preferred initiators are sodium persulfate and azobisamidinopropanehydrochloride. Alternatively, initiation of polymerization can be instituted by irradiation with ultra-violet light. The amount of initiator utilized is in general a sufficient amount to effect initiation of polymerization. Preferably they are present in amounts ranging from about 0.001 to about 10% by weight of monomer and more preferably less than about 0.5% by weight based on the total weight of the monomer, and most preferably from about 0.005 to about 0.5% by weight based upon the weight of the monomer. The initiator is added in the polymerization either continuously or in incremental additions. The continuous or incremental ad
Rice Richard E.
Yeung Dominic W. K.
Pezzuto Helen L.
Rhodia Inc.
Stevens Davis Miller & Mosher LLP
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