Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1997-09-08
2001-03-27
Henderson, Christopher (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C510S276000
Reexamination Certificate
active
06207780
ABSTRACT:
The present invention relates to water-soluble copolymers having OH-groups directly covalently bonded at the polymer chain and based on unsaturated mono- and dicarboxylic acids, vinyl esters or ethers, and sulfonic acid/sulfate-group-containing monomers. The present invention further relates to a process for their production and to their use in detergents and cleaners, in the inhibition of water hardness, as dispersing agents, and in the production, finishing and/or dyeing of textile fibers and textiles, and in the manufacture of leather.
Since ecological considerations have come to the fore within the last years, many of the efforts to develop new polymers have been focused on their biodegradability. Products whose application and disposal is effected in aqueous systems have been of particular interest. In some fields, for example, the papermaking industry, degradable polymers such as starches have been used as binders more frequently; in other fields, graft polymers of renewable raw materials, such as starch or sugar, and of synthetic monomers have been developed. However, for many applications there are relatively high technical requirements, and the products based on renewable raw materials are not able to meet these standards to the degree the purely synthetic polymers used until today do. A typical example is the use of polycarboxylates in mixed sizes for textile fibers; here a mixture of starch and polycarboxylate is frequently used as a compromise between degradability and sizing properties.
Another important field of application for water-soluble polymers is the use in detergents and cleaners.
During the last years, the development on this sector has been determined by the substitution of polyphosphate components which—as is generally known—result in overfertilization of the waters and, consequently, in the problems known as eutrophication.
In addition to the primary cleaning effect, polyphosphates have a favorable secondary detergent behavior; they remove alkaline-earth metal ions from the wash liquor, textiles and dirt, prevent precipitations of insoluble alkaline-earth metal salts on the textiles, and maintain the dirt in the washing liquor in disperse condition. In this manner incrustations and redepositions are suppressed even after several wash cycles. Due to their binding capacity for alkaline-earth ions and their dispersing and soil-carrying capacity, polycarboxylates, such as polyacrylic acids and acrylic acid/maleic acid copolymers, are currently on the market as substitutes for polyphosphates. The latter property is achieved in a particularly easy manner by using acrylic acid/maleic acid copolymers [Richter, Winkler in Tenside Surfactants Detergents 24 (1987) 4]. Such polymers are described, for example, in the patent applications DE 32 33 776 A1 and EP 76 992 B1.
DE 32 33 776 A1 describes a process for the production of copolymers comprising mono- and dicarboxylic units, which is characterized by using a specific hydrogen peroxide/peroxodisulfate-initiator ratio. According to this invention, 10-60%-wt. of dicarboxylic acid monomer/anhydride, 90-40%-wt. of monocarboxylic acid, and optionally 0-20%-wt. of monomers not containing carboxyl groups, which, however, are not regarded as absolutely necessary, are used and polymerized in aqueous medium at 60-150° C. under partial neutralization.
EP 76 992 B1 describes polymeric organic acids, a process for their production, and their use in detergents and cleaners. 50-95%-wt. of unsaturated monocarboxylic acid, 0.5-5%-wt. of monomers without acid function, and 0-49%-wt. of unsaturated dicarboxylic acid are reacted in a bulk polymerization process, and used in detergents as builder and incrustation inhibitor, optionally after neutralization. The acid-free monomers are selected from the group of vinyl and acrylic ester.
The problem of eutrophication has been answered with the use of polycarboxylates. However, these synthetic polymers must be regarded as being substantially inert towards degradation processes. Because of the already existing and the coming increasing spread of said polymers, the question of where they remain in the ecosystem arises. Examinations to this respect showed that about 90% of the polycarboxylates are adsorbed to and disposed by the sewage sludge, i.e. by dumping, agricultural utilization, or combustion. Biological degradation takes place to a very limited extent, the cited degradation rates amounting to between 1 and 10%. The statements to this respect can be found in the publications of J. Lester et al. “The partitioning of polycarboxylic acids in activated sludge”, Chemosphere, Vol. 21, Nos. 4-5, pp 443-450 (1990), H. Schumann “Elimination von
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C-markierten Polyelektrolyten in biologischen Abwasserreinigungsprozessen, Wasser—Abwasser (1991), pp 376-383, P. Berth “Möglichkeiten und Grenzen des Ersatzes von Phosphaten in Waschmitteln”, Angewandte Chemie (1975), pp 115-142.
Introducing large amounts of non-degradable compounds in the environment is critical from the ecological point of view. To solve this problem it seems to be obvious to use biodegradable polymers, i.e., those demineralizable to carbon dioxide and water, or to improve the effectiveness of commercial polycarboxylates in such a manner that the concentrations used can be lowered or that they can assume the functions of other detergent components in order to relieve the environment.
DE 43 27 494 A1 describes the production of polyaspartic acid imides. Such polycondensates are designed for the use as additives in detergents and cleaning agents. EP 633 310 A1 also describes the use of these polymers of limited biodegradability as builders in detergents. In general however, these polymers have a low binding and dispersing capability as compared to polycarboxylates, i.e., they are less effective. Under washing conditions, i.e., alkali and elevated temperature, they have the additional disadvantage of destroying the polymer by hydrolysis/saponification under simultaneous ammonia cleavage. These phosphate substitutes represent an ecological problem since the nitrogen bonded to the polymer would as a fertilizer promote the eutrophication of the waters already known from phosphates.
The production of a biodegradable polycarboxylate polymer based on glyoxylic acid esters is known from U.S. Pat. No. 4,144,226. To achieve technically interesting molecular weights, the mentioned polymerization method in anhydrous organic solvents requires temperatures of 0° C. or less, achieving polymer yields of only 75%, followed by further yield-reducing isolation and cleaning steps. Since the polymer is instable in the acid or alkaline pH-range, the end groups thereof must additionally be blocked chemically. Nevertheless, reduced molecular weight caused by chain scission involving loss of activity may occur during the detachment of the carboxyl groups from the ester form by means of saponification. Said polymers are not suitable for the use in large amounts in the aforementioned applications because very costly and commercially unavailable monomers and very expensive polymerization and processing techniques are to be employed, in addition they exhibit the described instability.
The patent GB 1 385 131 describes a detergent composition using a biodegradable polymer of maleic acid and vinyl alcohol units. The production process includes a precipitation polymerization in benzene, the separation and drying of the polymer, and its hydrolysis and saponification in an aqueous alkaline medium. Leaving the relatively complicated and costly production of these polymers out of consideration, additional disadvantages with respect to degradability and property profile become apparent. According to the indications relating to degradability, a drastic decrease in degradation goes along with the increase in molecular weight. A molecular weight increase from 4,200 to 18,000 already means a reduction in the degradation by 63%. With respect to the properties it must be mentioned that an inhibition of soil redeposition which is superior to sodium tripolyphosph
Berghahn Matthias
Klimmek Helmut
Krause Frank
Stockhausen Dolf
Henderson Christopher
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Rohm & Haas Company
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