DENTURE STABILIZING COMPOSITIONS

Abstract: Disclosed are adhesives and stabilizer compositions comprising a lower alkyl vinyl ether-maleic acid copolymer and their salts, said copolymer having a specific viscosity larger than 1.2, the sepcific viscosity being determined in methyl ethyl ketone at 25 DEG C and wherein said copolymer has a bulk density of from about 0.3 to about 1.2 grams per cubic centimeter and a specific surface area of from about 0.5 to about 2.5 square meters per gram.

Description: DENTURE STABILIZING COMPOSITIONS TECHNICAL FIELD This invention relates to improvements in adhesives, in par¬ ticular improved denture adhesives. BACKGROUND OF THE INVENTION Ordinary removable dentures, dental plates, and the like, com¬ prise teeth mounted in a suitable plate or base. Dentures function as a substitute for missing teeth and serve as a replacement for all or a portion of the teeth ordinarily found in the oral cavity. Although dentures generally are skillfully prepared, often they do not fit perfectly. Moreover, no matter how satisfactory at first, after a period of time the fit of the denture becomes " loose and imperfect due to natural shrinkage and changes in the gums, mucous tissues, and the like. Loose and imperfectly fitted dentures usually are corrected and stabilized by the use of a denture stabilizer. Denture stabilizers are used to fill the interstices between the dentures and the gums or tissues. Prior to placement of the denture in the oral cavity, a denture stabilizer is applied to the denture-plate surface which, for a perfect fit, should uniformly contact the gums and mucous tissues. The denture stabilizer is formulated not only for its adherent proper- ties, but also to provide a cushion or gasket between the denture and the gums or tissues, thereby positioning the denture securely in the oral cavity. Requirements and characteristics for a satisfactory denture stabilizing composition are many and are dictated by numerous factors. Desirably, one daily application of such a composition should function as an effective means for insulating, cushioning, and securely posi¬ tioning the denture. The composition should retain its characteris¬ tics and properties in the typical powder and cream forms during storage under various climatic conditions such as high temperature and humidity; be readily and easily capable of application to the denture surface; not be irritating or uncomfortable to the user; be safe and nontoxic; have no disagreeable odor or color; have no unpalatable taste; optionally provide antiseptic and germicidal properties for preventing or inhibiting the growth of organisms ordinarily found in the mouth; and function as an agent for prevention of putrefaction or malodorous decomposition of foods or secretions lodging beneath or adjacent to the denture. The stabilizing material must be capable of 5 imbibing water and saliva and swelling, so as to fill the interstices between the denture and the gum or mucous tissues. The stabilizer should not attack or damage the denture, as by causing a crazing of the denture-plate material. Additionally, the stabilizer should be stable to bacteria, molds and enzyme systems found in the oral cavity, 10 and have a pH that is nonirritating to the oral mucosa, generally 5-8.5, preferably a pH around neutrality. The mechanical strength of the stabilizing mass, be it gel or colloid, formed by imbibition of water should be great enough to securely maintain the position of the denture under normal use, and not so great as to make denture removal 15 difficult when desired, or as to damage or injure the gums, tissues or denture upon removal. There has been a considerable effort made over many years to develop improved denture adhesives. Both synthetic and natural polymers and gums have been used singly, in combination, and in 20 combination with various additives. European Patent 64,672 to Dhabhar and Schmidt, published November 17, 1982, relates to a hydrophilic denture adhesive containing an adhesive polymeric fraction comprising carboxymethylcellulose (CMC) and polyethylene oxide in a hydrophilic vehicle. 25 European Patent Application 140,486 to A.J. Des aris, filed July 31, 1984 relates to denture adhesive compositions containing a hydro- phobically modified water-soluble polymer, alone or admixed with an alkali metal salt of CMC. Hydrophobically modified hydroxyalkyl celluloses and copolymers of ethylene oxide and long chain epoxy- 30 alkanes are preferred for use in the compositions. U.S. Patent 4,280,936 to Dhabhar, Heyd and Schmidt, issued July 28, 1981, relates to improved denture adhesives containing a specified ratio of CMC and polyethylene oxide in a mineral oil base. U.S. Patent 4,474,902 to Dhabhar and Schmidt, issued October 2, 35 1984, relates to improved denture adhesives containing karaya gum in a hydrophilic vehicle. See also U.S. Patent 4,514,528, issued April 30, 1985, and U.S. Patent 4,518,721, issued May 21, 1985 to these same inventors, relating, respectively, to improved denture adhesives containing adhesive polymeric fractions consisting of admixtures of partial salts of lower alkylvinyl ether maleic anhydride-type copolymers with CMC or polyethylene oxide, as well as denture ad¬ hesives containing CMC and polyethylene oxide. See also U.S. Patent 4,522,956, issued June 11, 1985 to Dhabhar and Schmidt relating to improved denture adhesives containing polyethylene oxide as the sole adhesive component in a hydrophilic vehicle comprising certain poly¬ ethylene glycols. Other denture adhesives are described in U.S. Patents 4,530,942, issued July 23, 1989; 4,542,168, issued September 17, 1985; and 4,569,955, issued February 11, 1986. U.S. Patent 4,529,748 to H.G.P. Wienecke, issued July 16, 1985, relates to dental prosthesis adhesives formed from film-forming substances such as various cellulose derivatives, acrylate polymers, methacrylate polymers, and other film-providing substances. U.S. Patent 4,138,477 to Gaffar, issued February 6, 1979 dis¬ closes oral compositions to control mouth odor containing zinc-polymer combinations formed from zinc reacted with an anionic polymer contain¬ ing carboxylic, sulfonic and/or phosphonic acid radicals. U.S. Patent 3,003,988, to D.P. Ger ann et al., issued October 10, 1961, describes certain water-sensitized, but water-insoluble, materi¬ als for stabilizing dentures which are synthetic, hydrophilic, col¬ loidal materials comprising mixed partial salts and esters of lower alkyl (1 to 4 carbons) vinyl ether-maleic anhydride-type copolymers, said mixed partial salts and esters containing both divalent calcium and monovalent alkali (i.e., sodium, potassium and ammonium) cations. U.S. Patent 4,758,630 to Shah et al., issued July 19, 1988 relates to zinc and strontium partial salts of lower alkyl (C x to C 4 ) vinyl ether-maleic acid copolymers, wherein said zinc and strontium cations are "unmixed" with any other cations or ester functions in the copolymeric salt, the remaining initial carboxyl groups being unreact- ed. These lower alkyl vinyl ether-maleic acid copolymers are referred to hereinafter by the abbreviated term "AVE/MA copolymer" and the methyl vinyl ether-maleic acid copolymer as "MVE/MA copolymer". Further, European Patent Application 396,411, to Holeva and Gounaris published November 7, 1990, discloses mixed partial MVE/MA copolymer salts. It is known, therefore, that combinations of mixed and unmixed partial salts of lower alkyl vinyl ether-maleic anhydride-type co¬ polymers are useful as denture adhesive compositions. Yet, the search continues for denture stabilizers that will provide the above-described characteristics and, importantly, will maintain the secure fit of the denture over prolonged periods (10-14 hours) without the need for reapplication. In accordance with the present invention, improved adhesive and other characteristics are obtained in a denture stabilizing composi- tion by using specific acids and partial salt(s) of a lower alkyl vinyl ether-maleic acid copolymer with a specified bulk density and specific surface area. It is an object of the present invention to provide improved denture stabilizers which are easy to manufacture and that will be stable over prolonged periods in the oral cavity, yet will allow easy removal of the denture on demand. It is a further object to provide such stabilizers using toxico- logically-acceptable, palatable materials. It is another object herein to provide stabilizers that perform well in the presence of moisture, particularly in the presence of body fluids such as saliva, perspiration and blood. These and other objects are secured by the present invention, in the manner disclosed hereinafter. SUMMARY OF THE INVENTION The present invention encompasses adhesives and stabilizer compositions comprising: a lower alkyl vinyl ether-maleic acid copolymer consisting essentially of the repeated structural unit: wherein R represents a C x to C 4 alkyl radical, n is an integer greater than one representing the number of repeated occurrences of said structural unit in a molecule of said copolymer and n is large enough to characterize said copolymer as having a specific viscosity larger than 1.2, the specific viscosity being determined in methyl ethyl ketone at 25 β C and wherein said copolymer has a bulk density of from about 0.3 to about 1.2 grams per cubic centimeter and a specific surface area of from about 0.5 to about 2.5 square meters per gram. Preferably these copolymers are partial salts (mixed or unmixed, preferably mixed), said partial salts containing from about 10% to about 40% free acid, and as the cationic salt function, from about 0.1% to about 85% of the total initial carboxyl groups reacted with one or more of a cationic salt function selected from the group consisting of zinc cations, strontium cations, sodium cations, calcium cations, magnesium cations, potassium cations and ammonium cations and mixtures thereof and wherein said copolymer has a bulk density of from about 0.3 to about 1.2 grams per cubic centimeter and a specific surface area of from about 0.5 to about 2.5 square meters per gram. Also disclosed are denture stabilizing compositions comprising a safe and adhesively effective amount of two or more denture adhesive components wherein one of said denture adhesive components is either the copolymer or the mixed partial salt(s) of " the present invention. Bulk densities are measured according to ASTM method B-52 (02.05). Preferably these copolymers or mixed partial salts are used along with a water-sensitized polymeric material selected from the group consisting of natural gums, synthetic polymers, saccharide deriva¬ tives, cellulose derivatives, and mixtures thereof. All percentages and ratios used herein relating to the neutrali¬ zation of the salts of the present invention are based upon the stoichiometric percent of the cations present in the salt. All percentages and ratios used herein are by weight, unless otherwise specified. DETAILED DESCRIPTION OF THE INVENTION The present invention encompasses stabilizer compositions com¬ prising: a lower alkyl vinyl ether-maleic acid copolymer consisting essentially of the repeated structural unit: wherein R represents a C x to C 4 alkyl radical, n is an integer greater than one representing the number of repeated occurrences of said structural unit in a molecule of said copolymer and n is large enough to characterize said copolymer as having a specific viscosity larger than 1.2, the specific viscosity being determined in methyl ethyl ketone at 25'C and wherein said copolymer has a bulk density of from about 0.3 to about 1.2 grams per cubic centimeter and a specific surface area of from about 0.5 to about 2.5 square meters per gram. Preferably these copolymers are partial salts, said partial salts containing from about 10% to about 40% free acid, and as the cationic salt function from about 0.1% to about 85% of the total initial carboxyl groups reacted with one or more of a cationic salt function selected from the group consisting of zinc cations, strontium cations, sodium cations, calcium cations, magnesium cations, potassium cations and ammonium cations and mixtures thereof and wherein said copolymer has a bulk density of from about 0.3 to about 1.2 grams per cubic centimeter and a specific surface area of from about 0.5 to about 2.5 square meters per gram. Preferably the partial salts (preferably mixed) comprise from about 0.1% to about 85% of one or more of the above mentioned cations in the following levels: from about 0.1% to about 65%, more pre¬ ferably from about 2% to about 45%, and most preferably from about 2.5% to about 30% zinc or strontium cations (preferably zinc), and from about 10% to about 75%, more preferably from about 20% to about 65%, and most preferably from about 40% to about 65% calcium cations, from about 0.1% to about 25%, and more preferably from about 0.1% to about 20% sodium cations and from about 10% to about 40%, most pre- ferably from about 20% to about 35% free acid. The subject polymeric salts are advantageously prepared by the interaction of the AVE/MA copolymer (I) with the optional cationic calcium, sodium, ammonium and either zinc or strontium compounds having a functional group typical of reactants of carboxylic acid, such as, for example, the hydroxide, acetate, carbonate, halide, lactate, etc. in an aqueous medium. In a preferred embodiment, the oxide of zinc and the hydroxide of calcium and sodium are utilized. Since zinc hydroxide is not commercially available, its use as a reactant is readily and more economically accomplished by employing an aqueous slurry of particulate zinc oxide which, although practically insoluble in water, provides hydration to zinc hydroxide on the particulate surface. Calcium and sodium hydroxides as well as stron¬ tium hydroxide, on the other hand, are available in either crystalline or powder form and are soluble in about 50 parts water. Aqueous solutions of strontium oxide, however, which form the hydroxide when treated with water (caution: heat evolution), may also be used. Strontium carbonate may also be used. Anions that form toxic, irritating or contaminating by-products should be avoided, or special precautions and treatment provided to assure the removal and absence of such by-products from the polymeric salt end-product. The particular compound used should be substantial¬ ly pure to assure obtaining a substantially pure, substantially off-white polymeric salt end-product. The lower alkyl vinyl ether aleic acid (AVE/MA) copolymers (I) are readily obtained by copoly erizing a lower alkyl vinyl ether monomer, such as methyl vinyl ether, ethyl vinyl ether, divinyl ether, propyl vinyl either and isobutyl vinyl ether, with maleic anhydride to yield the corresponding lower alkyl vinyl ether-maleic anhydride copolymer which is readily hydrolyzable to the acid copolymer (I). Both anhydride and acid forms are also available from commercial suppliers. For example, the GAF Corporation, Wayne, New Jersey, provides both the polymeric free acid form (I) and the corresponding anhydride form under its "GANTREZ" trademark as the "GANTREZ S Series" and "GANTREZ AN Series", respectively. In the former acid series, the GANTREZ S-97 (M.W.=50,000) is particularly suitable, and, in the latter anhydride series, the GANTREZ AN-149 (M.W.=50,000), the GANTREZ AN-169 (M.W.=67,000) and the GANTREZ AN-179 (M.W.=80,000) copolymers are particularly suitable. Said acid and anhydride forms of AVE/MA copolymers, having an average molecular weight of from about 50,000 to about 80,000 (as measured by membrane osmometry in 2-butanone 1-10 grams/1000 ml solution), are also characterized by having the previ¬ ously described specific viscosity parameter of more than 1.2. When the anhydride copolymer dissolves in water, the anhydride linkage is cleaved so that the highly polar, polymeric free acid (I) is formed. Accordingly, the anhydride form, which is relatively less expensive than the acid form, may be used as a convenient and cheaper precursor for the acid. Elevated temperatures may be advantageously employed to enhance the rate of anhydride-to-acid hydrolysis. In general, the lower alkyl vinyl ether-maleic acid copolymer (I), or its corresponding anhydride, is added to water preheated to about 70-80'C with vigorous stirring to form a homogeneous mixture. If the anhydride precursor is utilized, it is recommended that the aqueous mixture be further heated to about 90 * C with stirring to ensure complete hydrolysis of the anhydride to the acid form. Heating is then discontinued although mixing is continued until the batch turns clear with a simultaneous decrease in viscosity (about 65-75'C). In a preferred embodiment, an aqueous solution of the cationic zinc or strontium salt forming compound, or, for example, an aqueous dispersion of particulate zinc oxide is combined with calcium hy¬ droxide in the form of a slurry, in an amount sufficient to provide the desired zinc and calcium cationic content desired in the end-product, is separately prepared at ambient temperature and slowly added to the hot polymeric acid solution with continuous vigorous mixing so as to prevent localized precipitation of the cationic polymeric salt. After the calcium and zinc have reacted, an aqueous solution of sodium hydroxide is added slowly, in the amount sufficient to provide the cation sodium content desired in the end-product. After addition is complete, mixing is continued to ensure that all the salt forming compounds are reacted with the copolymer. Alternatively for this preferred embodiment, an aqueous solution containing the zinc and calcium source is preheated to 70-80'C with vigorous stirring to form a homogeneous slurry. The lower alkyl vinyl ether-maleic acid copolymer (I) or its corresponding anhydride is then added to the slurry while further heating to 90 * C and stirring to ensure complete hydrolysis. Alternatively, the AVE/MA copolymer, calcium, and strontium zinc oxide powders are slurried in water at 25 * and subsequently heated to 80'C - 90'C for reaction to occur. Upon completion of this reaction step an aqueous solution of sodium hy¬ droxide is slowly added. The zinc (or strontium), calcium, and sodium cations in the resultant mixed partial salt of AVE/MA copolymer should be sufficient to give a neutralization ranging from about 10% to about 75%, prefera¬ bly from about 20% to about 65%, and most preferably from about 40% to about 65% calcium, and from about 0.1% to about 65%, preferably from about 2% to about 45%, and most preferably from about 2.5% to about 30% zinc or strontium, and from about 0.1% to about 25%, preferably from 0.1% to about 20% sodium, resulting in a salt containing free acid in the range of from about 10% to about 40%, preferably from about 20% to about 35%. The reaction batch is then dried using drum dryers maintained at 80-100 PSIG with hot steam to evaporate the water content and recover the polymeric salt with a high specific surface area, in the flake form. The resulting flakes are subjected to milling and screening to yield the desired physical properties to provide satisfactory denture stabilizing properties while maintaining the desired high specific surface areas. These surface areas can be obtained by any appropriate micronizing technique, preferably air jet milling or pin/disk or hammer milling as described in Remingtons Pharmaceutical Sciences (16th edition) pp. 1535-1539, incorporated by references herein. Said salts are friable so that appropriate particle size and bulk density can be obtained. For best results, drum dried particles should be milled to a preferred bulk density of about 0.3 to about 1.2 more preferably about 0.6 to about 1.2 and most preferably about 0.7 to about 1.2 grams per cubic centimeter while maintaining a specific surface area of about 0.5 to about 2.5, more preferably about 0.6 to about 2.5, and most preferably about 0.7 to about 2.0 square meters per gram. Ground particles should be capable of passage through a 140- to 200-mesh sieve (U.S.B.S. series) and preferably are less than 0.3 millimeters in their largest dimension. The subject acid copolymers and their respective salts have exceptional adhesive qualities when contacted with water or saliva such that they are extremely useful as denture adhesive materials in denture stabilizing compositions. For such use the salt in particu- late form is preferably characterized by a particle size of at least minus 140-mesh U.S.B.S. sieve; a bulk density greater than 0.3 gram per cubic centimeter and preferably higher then 0.6 gram per cubic centimeter; and a pH between 3 and 8 and preferably between 5 and 7.5, the pH being determined on a one percent by weight dispersion in water. Each of the subject copolymer salts may be utilized in effective adhesive amounts, preferably at least 25 percent by weight, as the sole adhesive component or as a co-adhesive in joint usage with other active adhesive components in denture stabilizing compositions. It is preferred that said copolymer salt be used along with a co-adhesive in denture stabilizing compositions. Preferably, the co-adhesive is a polymeric material selected from the group consisting of natural gums, synthetic polymers, saccharide derivatives, cellulose derivatives, and mixtures thereof. In general, from about 15 to about 70 percent, based on the total weight of the composition, of said mixed calcium/sodium/zinc or strontium salt is present. Preferred co-adhesives include a water-soluble hydrophilic colloid or polymer having the particular property of swelling upon exposure to moisture to form a mucilaginous mass. Such adhesive materials include both natural gums and synthetic polymeric gums and, among those commonly employed in denture stabilizing compositions and which are also suitable herein co-adhesive action with the subject mixeα AVE/MA copolymer salts, there may be mentioned, for example, karaya gum, gelatin, algin, sodium alginate, tragacanth, methylcellu¬ lose, acrylamide polymers, ethylene oxide polymers, polyvinylpyrroli- done, cationic polyarylamide polymers and, as the most preferred, sodium carboxymethylcellulose and mixed partial salts of poly(vinyl methylether-maleic acid) copolymer. Accordingly, a preferred aspect of the subject invention provides adhesives and denture stabilizing compositions having as a stabilizing component an effective adhesive amount of a lower alkyl vinyl ether-maleic acid copolymer consisting essentially of the repeated structural unit: OR —-CH 2 CH wherein R represents a C x to C 4 alkyl radical, n is an integer greater than one representing the number of repeated occurrences of said structural unit in a molecule of said copolymer and n is large enough to characterize said copolymer as having a specific viscosity larger than 1.2, the specific viscosity being determined in methyl ethyl ketone at 25"C and wherein said copolymer has a bulk density of from about 0.3 to about 1.2 grams per cubic centimeter and a specific surface area of from about 0.5 to about 2.5 square meters per gram. Preferably these copolymers are partial salts, said partial salts containing from about 10% to about 40% free acid, and as the cationic salt function from about 0.1% to about 85% of the total initial carboxyl groups reacted with one or more of a cationic salt function selected from the group consisting of zinc cations, strontium cations, sodium cations, calcium cations, magnesium cations, potassium cations and ammonium cations and mixtures thereof and wherein said copolymer has a bulk density of from about 0.3 to about 1.2 grams per cubic centimeter and a specific surface area of from about 0.5 to about 2.5 square meters per gram. Another preferred aspect of this invention provides a denture stabilizing composition comprising a safe and adhesively effective amount of at least two denture adhesive components, wherein one of said denture adhesive components is the acid or partial salt of a lower alkyl vinyl ether-maleic acid copolymer described above. Preferably the co-adhesive is as described above. The compositions of the present invention can optionally include from about 0.01% to about 5% of one or more components which provide the user with sensory, including flavor, benefits. Suitable compo¬ nents include menthol, menthyl lactate, peppermint oil, spearmint oil, peppermint oil, leaf alcohol, as well as those paramenthane carboxy- amides flavoring agents available from Wilkinson-Sword (such as WS-3) which are described in U.S. Patent 4,136,163 to Watson et al., issued January 23, 1979 which is incorporated by reference herein. The compositions of the present invention are manufactured in an art-recognized manner known to those skilled in the art, such as in a powder, cream, ointment, liquid, paste, water or film. The compo¬ sitions of the present invention are preferably manufactured with drum dried AVE/MA copolymers or their salts that are milled using appro¬ priate micronization techniques such as fluid energy or air jet or hammer milling of drum dried mixed partial salts of AVE/MA copolymer. Suitable examples of such formulations are disclosed in U.S. Patent 4,518,721, issued May 21, 1985 and U.S. Patent 4,514,528, issued April 30, 1985, both to Dhabhar et al . and both of which are hereby incor¬ porated by reference herein. Preferably, these compositions contain from about 10% to about 70% of one or more ointment bases. Preferably, this base is mineral oil or petrolatum, however polyethylene glycol, paraffin, glycerin and mixtures thereof are also useful. Most preferred is a mixture of mineral oil and petrolatum. It is to be recognized that the adhesive salts of the present invention can be used for a wide variety of general adhesive uses including, but not limited to, pharmaceutical uses (e.g., oral drug delivery and topical bandages); and aqueous adhesives (e.g., where adhesiveness in the presence of water is required). The following non-limiting examples illustrate embodiments of the subject invention wherein both essential and optional ingredients are combined. It is to be understood that these examples are for illus¬ trative purposes only and are not to be construed as limiting the scope of the invention thereto. Example I Into a reaction vessel equipped with a high speed stirrer and containing 94 parts (4.7 kg) of purified water heated to 85'C, is slowly added 6 parts (300 grams) methyl vinyl ether-maleic anhydride copolymer to the reaction vessel over a 15 minute period. Temperature and mixing remain constant for 60 minutes after 15 minutes, the resulting adhesive polymeric dispersion is characterized by an in¬ crease in viscosity, and a decrease and stabilization of reaction pH which is a dispersion of said material in water, said material con¬ sisting of acid form of methyl vinyl ether-maleic acid copolymer. The resultant solution of the methyl vinyl ether-maleic acid (MVE/MA) copolymer is then dried using a drum dryer maintained at 80-100 PSIG with hot steam to evaporate the water content and recover the polymeric salt with a high specific surface area, in flake form. The thus obtained dried acid form of the MVE/MA copolymer is then ground using an air jet or hammer mill to a bulk density of about 0.7 to about 1.1 grams per cubic centimeter while maintaining a specific surface area ~~ όf about 0.7 to about 1.5 square meters per gram. This copolymer is then screened through a 140-mesh sieve and then through a 200 mesh sieve (U.S.B.S. sieve series). The powder has a pH of about 2.5 for a one percent solution in water. This particular copolymer will be referred to hereinafter by the abbreviated term, "acid form of MVE/MA copolymer". The product, when used in conjunction with conventional denture adhesives and applied to wet dentures with normal usage, provides denture stabilizing characteristics superior to those obtained by the particular conventional denture adhesive itself. Example II Into a reaction vessel equipped with a high speed stirrer and containing 92.1 parts (1.842 kg) of purified water heated to 85'C, is slowly added calcium hydroxide 1.9 parts (37.9 grams), and sodium hydroxide 0.3 parts (5.8 grams). After addition is complete, the temperature of the slurry is kept constant with high speed mixing. While keeping heat and mixing constant add 5.71 parts (114 grams) of methyl vinyl ether-maleic anhydride copolymer to the reaction vessel containing the alkali dispersion over a 15 minute period. Temperature and mixing remain constant for 60 minutes. After 15 minutes the resulting adhesive polymeric dispersion is characterized by an in¬ crease in viscosity, and a decrease and stabilization of the reaction pH which is a dispersion of said material in water, said material consisting of mixed partial calcium sodium salt of methyl vinyl ether- maleic acid copolymer. The resultant solution of the calcium sodium salt of methyl vinyl ether-maleic acid (MVE/MA) copolymer is then dried using a drum dryer maintained at 80-100 PSIG with hot steam to evaporate the water content and recover the polymeric salt with a high specific surface area, in flake form. The thus obtained dried calcium sodium MVE/MA copolymer salt is then ground using an air jet or hammer mill to a bulk density of about 0.7 to about 1.1 grams per cubic centimeter while maintaining a specific surface area of about 0.7 to about 1.5 square meters per gram. This copolymer is then screened through a 140-mesh sieve and then through a 200 mesh sieve (U.S.B.S. sieve series). The powder has a pH of about 6.5 for a one percent solution in water. Analysis of the salt indicates about 70.0 percent neutrali¬ zation with calcium, 10.0 percent neutralized with sodium with 20% remaining carboxyl groups. This particular salt will be referred to hereinafter by the abbreviated term, "70% Ca/10% Na partial salt of MVE/MA copolymer". The product, when used in conjunction with conventional denture adhesives and applied to wet dentures with normal usage, provides denture stabilizing characteristics superior to those obtained by the particular conventional denture adhesive itself. Example III Into a reaction vessel equipped with a high speed stirrer and containing 92.4 parts (4.6 kg) of purified water heated to 85'C, is slowly added 0.53 parts (26.3 grams) of zinc oxide and calcium hy- droxide 1.30 parts (64.6 grams). After addition is complete, the temperature of the slurry is kept constant with high speed mixing. While keeping heat and mixing constant add 5.76 parts (288 grams) of methyl vinyl ether-maleic anhydride copolymer to the reaction vessel containing the alkali dispersion over a 15 minute period. Temperature and mixing remain constant for 60 minutes. After 15 minutes the resulting adhesive polymeric dispersion is characterized by an in¬ crease in viscosity, and a decrease and stabilization of the reaction pH which is a dispersion of said material in water, said material consisting of mixed partial calcium zinc salt of methyl vinyl ether- maleic acid copolymer. The resultant solution of the calcium zinc salt of methyl vinyl ether-maleic acid (MVE/MA) copolymer is then dried using a drum dryer maintained at 80-100 PSIG with hot steam to evaporate the water content and recover the polymeric salt with a high specific surface area, in flake form. The thus obtained dried calcium zinc MVE/MA copolymer salt is then ground using an air jet or hammer mill to a bulk density of about 0.7 to about 1.1 grams per cubic centimeter while maintaining a specific surface area of about 0.7 to about 1.5 square meters per gram. This copolymer is then screened through a 140-mesh sieve and then through a 200 mesh sieve (U.S.B.S. sieve series). The powder has a pH of about 5.4 for a one percent solution in water. Analysis of the salt indicates about 47.5 percent neutrali¬ zation with calcium, 17.5 percent neutralized with zinc with 35% remaining carboxyl groups. This particular salt will be referred to hereinafter by the abbreviated term, "47.5% Ca/17.5% Zn partial salt of MVE/MA copolymer". The product, when used in conjunction with conventional denture adhesives and applied to wet dentures with normal usage, provides denture stabilizing characteristics superior to those obtained by the particular conventional denture adhesive itself. Example IV Into a reaction vessel equipped with a high speed stirrer and containing 84.7 parts (7.6 kg) of purified water heated to 85 β C, is slowly added. 0.2 parts (18 grams) of zinc oxide and calcium hy- droxide 0.92 parts (82.7 grams). After addition is complete, the temperature of the slurry is kept constant with high speed mixing. While keeping heat and mixing constant add 3.9 parts (348 grams) of methyl vinyl ether-maleic anhydride copolymer to the reaction vessel containing the alkali dispersion over a 15 minute period. At about 15 minutes the resulting adhesive polymeric dispersion is characterized by an increase in viscosity, and a decrease and stabilization of the reaction pH which is a dispersion of said material in water, said material consisting of mixed partial calcium zinc salt of methyl vinyl ether-maleic acid copolymer. Temperature and mixing remain constant for 60 minutes. Next, 890 grams of a 1% solution of sodium hydroxide is slowly added over a 30 minute period and the reaction is allowed to go to completion as indicated by the stabilization of the reaction pH. The resultant solution of the calcium zinc salt of methyl vinyl ether-maleic acid (MVE/MA) copolymer is then dried using a drum dryer maintained at 80-100 PSIG with hot steam to evaporate the water content and recover the polymeric salt with a high specific surface area, in flake form. The thus obtained dried calcium zinc MVE/MA copolymer salt is then ground using an air jet or hammer mill to a bulk density of about 0.7 to about 1.1 grams per cubic centimeter while maintaining a specific surface area of about 0.7 to about 1.5 square meters per gram. This copolymer is then screened through a 140-mesh sieve and then through a 200 mesh sieve (U.S.B.S. sieve series). The powder has a pH of about 5.7 for a one percent solution in water. Analysis of the salt would indicate about 50 percent of the carboxyl groups neutralized with calcium, 9.9 percent neutralized with zinc and 5% neutralized with sodium with 35% carboxyl groups remaining unreacted. This particular salt will be referred to here¬ inafter by the abbreviated term, "50% Ca/9.9% Zn/ 5% Na partial salt of MVE/MA copolymer". The product, when used in conjunction with conventional denture adhesives and applied to wet dentures with normal usage, provides denture stabilizing characteristics superior to those obtained by the particular conventional denture adhesive itself. Example V Into a reaction vessel equipped with a high speed stirrer and containing 85.1 parts (7.7 kg) of purified water heated to 85 * C, is slowly added 0.1 parts (9 grams) of zinc oxide and calcium hydroxide 1.1 parts (98.9 grams). After addition is complete, the temperature of the slurry is kept constant with high speed mixing. While keeping heat and mixing constant add 3.9 parts (347.2 grams) of methyl vinyl ether-maleic anhydride copolymer to the reaction vessel containing the alkali dispersion over a 15 minute period. At about 15 minutes the resulting adhesive polymeric dispersion is characterized by an in¬ crease in viscosity, and a decrease and stabilization of the reaction pH of the dispersion of said material in water, said material con¬ sisting of mixed partial calcium zinc salt of methyl vinyl ether- maleic acid copolymer. Temperature and mixing remain constant for 60 minutes. Next, 890 grams of a 1% solution of sodium hydroxide is slowly added over a 30 minute period and the reaction is allowed to go to completion as indicated by stabilization of the reaction pH. The resultant solution of the calcium zinc salt of methyl vinyl ether-maleic acid (MVE/MA) copolymer is then dried using a drum dryer maintained at 80-100 PSIG with hot steam to evaporate the water content and recover the polymeric salt with a high specific surface area, in flake form. The thus obtained dried calcium zinc MVE/MA copolymer salt is then ground using an air jet or hammer mill to a bulk density of about 0.7 to about 1.1 grams per cubic centimeter while maintaining a specific surface area of about 0.7 to about 1.5 square meters per gram. This copolymer is then screened through a 140-mesh sieve and then through a 200 mesh sieve (U.S.B.S. sieve series). The powder has a pH of about 6.0 for a one percent solution in water. Analysis of the salt would indicate about 60% of the carboxyl groups neutralized with calcium, 5% neutralized with zinc, and 5% neutralized with sodium with 30% of the carboxyl groups re¬ maining unreacted. This particular salt will be referred to here¬ inafter by the abbreviated term, "60% Ca/5% Zn/5% Na partial salt of MVE/MA copolymer". The product, when used in conjunction with conventional denture adhesives and applied to wet dentures with normal usage, provides denture stabilizing characteristics superior to those obtained by the particular conventional denture adhesive itself. Examol e VI The procedure of Example I is repeated except that the following amounts of reactants are employed: 3.9 parts (77.3 grams) of the anhydride copolymer, 94.9 parts (1.9 kg) purified water; and 0.2 parts (3.99 grams) of zinc oxide; 0.2 parts (3.99 grams) of sodium hydroxide and 0.83 parts (16.5 grams) calcium hydroxide. The resultant powder would have a bulk density of about 0.7 to about 1.1 grams per cubic centimeter and a specific surface area of about 0.7 to about 1.5 square meters per gram. Analysis of the salt indicates about 45 percent calcium neutralization of the total initial carboxyl groups in the copolymer salt molecule; 9.9 percent neutrali¬ zation with zinc and 10% neutralization with sodium will be referred to hereinafter by the abbreviated term "45% calcium/9.9% zinc/10% sodium partial salt of MVE/MA copolymer". Example VII By following the general procedure of Example V, except that an appropriate amounts of zinc oxide, calcium hydroxide and sodium hydroxide are utilized to provide the tabulated substitutions, the following calcium/zinc/sodium salts of MVE/MA copolymer are obtained: Sodium Calcium Zinc 0 60 5 5 55 5 10 60.5 2.5 10 65 2.5 15 40 9.9 20 40 9.9 5 55 9.9 Each of the indicated MVE/MA copolymer salts, which would have, for the minus 140-mesh U.S.B.S. sieve powder, a bulk density greater than 0.5 grams per cubic centimeter, while maintaining a specific surface area greater than 0.6 square meters per gram and provides markedly beneficial denture stabilizing characteristics. Each of the indicated salts may be abbreviated by the percent of calcium/percent of zinc/percent sodium neutralization as done in Examples I through V. Example VIII The MVE/MA copolymeric anhydride-to-acid hydrolysis procedure outlined in Example V is repeated. To a vessel containing 8.5 kg of purified water heated to 85°C is added 16.5 grams of strontium hy- droxide octahydrate. With vigorous mixing, 99.4 grams of calcium hydroxide is slowly added. After addition is complete, the tempera¬ ture of the slurry is kept constant with high speed mixing. While maintaining the heat and constant mixing, 34.9 grams of methyl vinyl ether-maleic anhydride copolymer are added to the reaction vessel containing the alkali dispersion over a 20 minute period. This produces a mixed partial calcium strontium salt of methyl vinyl ether-maleic acid copolymer. Example IX Denture stabilizing powder compositions are prepared by blending together the following: A. Karaya gum Sodium carboxymethylcellulose Sodium borate 47.5% Ca/17.5% Zn mixed partial salt of MVE/MA copolymer 60% Ca/5% Zn/5% Na partial salt of MVE/Ma copolymer B. Sodium alginate Sodium carboxymethylcellulose Polyvinylpyrrolidone (average M.W.=90,000) 65% Ca/10% Zn mixed partial salt of PVM/MA copolymer 20 60.5% Ca/2.5% Zn/ 10% Na partial salt of MVE/MA copolymer . 20 100 100 C. Sodium carboxymethylcellulose 50 50 70% Ca/10% Na mixed partial salt of MVE/MA copolymer 50 30 50% Zn unmixed partial salt of MVE/MA copolymer ^ 20 100 100 D. Gantrez S-97 acid copolymer Sodium carboxymethylcellulose 70% Ca/10% Na mixed partial salt of MVE/MA copolymer Said free acid MVE/MA copolymer, and the indicated mixed or unmixed partial salts of MVE/MA copolymer which would have for the minus 140-mesh U.S.B.S. sieve powder, a bulk density greater than 0.5 grams per cubic centimeter while maintaining a specific surface area greater than 0.6 square meters per gram. In use, the above powders (typically 0.1-1 g) are placed on a premoistened denture, allowed to hydrate briefly, and the denture is inserted in the mouth and pressed into place, all in the manner of denture adhesives well-known in the art. Example X Liquid-type denture stabilizing compositions are prepared by mixing together the following: % w w Mineral oil, heavy Petrolatum Colloidal silica Sodium carboxymethylcellulose Menthol 47.5% Ca/17.5% Zn mixed partial salt of MVE/MA copolymer 55% Ca/5% Zn/10% Na mixed partial salt of MVE/MA copolymer 100.0 100.0 In use, the above liquids (typically 0.1-1 g) are placed on a premoistened denture, allowed to hydrate briefly, and the denture is inserted in the mouth and pressed into place, all in the manner of denture adhesives well-known in the art. Example XI Cream-type denture stabilizing compositions are prepared by mixing together the following: Mineral oil, heavy Sodium carboxymethylcellulose Petrolatum Silicon dioxide, colloidal Colorant (oil soluble red color dispersion) 0.060 0.060 0.060 47.5%Ca/17.5%Zn mixed partial salt of MVE/MA copolymer 33.000 55.0%Ca/5%Zn/10%Na mixed partial salt of MVE/MA copolymer 33.000 70% Ca/10% Na partial mixed salt of MVE/MA copolymer 16.500 50% Zn unmixed partial salt of MVE/MA copolymer 16.500 Said free acid MVE/MA copolymer, and the indicated mixed or unmixed partial salts of MVE/MA copolymer which would have for the minus 140-mesh U.S.B.S. sieve powder, a bulk density greater than 0.5 grams per cubic centimeter while maintaining a specific surface area greater than 0.6 square meters per gram. In use, the above creams (typically 0.1-2 g) are placed on a premoistened denture, allowed to hydrate briefly, and the denture is inserted in the mouth and pressed into place, all in the manner of denture adhesives well-known in the art. WHAT IS CLAIMED IS:

Claims: A l ower al kyl vi nyl ether-mal eic acid copolymer consi sting essential ly the repeated structural unit : wherein R represents a Ci to C 4 alkyl radical, preferably methyl, n is a integer greater than one representing the number of repeated occurrence of said structural unit in a molecule of said copolymer and n is larg enough to characterize said copolymer as having a specific viscosit larger than 1.2, the specific viscosity being determined in methyl ethy ketone at 25 β C and wherein said copolymer has a bulk density of from 0. to 1.2 grams per cubic centimeter and a specific surface area of from 0. to 2.5 square meters per gram. The partial salt of a lower alkyl vinyl ether-maleic acid copolyme consisting essentially of the repeated structural unit: wherein R represents a C_ to C 4 alkyl radical, preferably methyl, n is a integer greater than one representing the number of repeated occurrence of said structural unit in a molecule of said copolymer and n is larg enough to characterize said copolymer as having a specific viscosit larger than 1.2, the specific viscosity being determined in methyl ethy ketone at 25 * C, said partial salts containing from 10% to 40% free acid and as the cationic salt function from 0.1% to 85% of the total initia carboxyl groups reacted with one or more of a cationic salt functio selected from the group consisting of zinc cations, strontium cations sodium cations, calcium cations, magnesium cations, potassium cations an ammonium cations and mixtures thereof and wherein said copolymer has bulk density of from 0.3 to 1.2 grams per cubic centimeter and a specifi surface area of from 0.5 to 2.5 square meters per gram. The partial salt of Claim 3 wherein said cationic salt function i selected from the group of zinc, strontium, calcium, and sodium cation and mixtures thereof and comprises: (a) from 0.1% to 65% zinc or strontium cations, preferably 2.5% to 30% zinc cations,; and (b) from 0.1% to 75% calcium cations or sodium cations, preferably fro 5% to 20% sodium cations or mixture thereof; and (c) from 40% to 70% calcium cations of the total initial carboxyl groups reacted and from 10% to 40% free acid and wherein said salt has a bulk density of from 0.6 to 1.2 grams pe cubic centimeter and a specific surface area of from 0.6 to 2.5 square meters per gram. 4. A denture stabilizing composition having as a stabilizing component an effective adhesive amount of a lower alkyl vinyl ether-maleic acid copolymer consisting essentially of the repeated structural unit: wherein R represents a C x to C alkyl radical, preferably methyl, n is an integer greater than one representing the number of repeated occurrences of said structural unit in a molecule of said copolymer and n is large enough to characterize said copolymer as having a specific viscosity larger than 1.2, the specific viscosity being determined in methyl ethyl ketone at 25 β C and wherein said copolymer has a bulk density of from 0.3 to 1.2 grams per cubic centimeter and a specific surface area of from 0.5 to 2.5 square meters per gram. 5. A denture stabilizing composition having as a stabilizing component a effective adhesive amount of a mixed partial salt of a lower alkyl viny ether-maleic acid copolymer consisting essentially of the repeate structural unit: wherein R represents a C x to C 4 alkyl radical, preferably methyl, n is a integer greater than one representing the number of repeated occurrence of said structural unit in a molecule of said copolymer and n is larg enough to characterize said copolymer as having a specific viscosit larger than 1.2, the specific viscosity being determined in methyl ethy ketone at 25'C, said partial salts containing from 10% to 40% free acid and as the cationic salt function from 0.1% to 85% of the total initia carboxyl groups reacted with one or more of a cationic salt functio selected from the group consisting of zinc cations, strontium cations sodium cations, calcium cations, magnesium cations, potassium cations an ammonium cations and mixtures thereof and wherein said copolymer has bulk density of from 0.3 to 1.2 grams per cubic centimeter and a specifi surface area of from 0.5 to 2.5 square meters per gram. The partial salt of Claim 3 wherein said cationic salt function i selected from the group of zinc, strontium, calcium, and sodium cation and mixtures thereof and comprises: (a) from 0.1% to 65% zinc or strontium cations, preferably 2.5% to 30% zinc cations,; and (b) from 0.1% to 75% calcium cations or sodium cations, preferably fro 5% to 20% sodium cations or mixture thereof; and (c) from 40% to 70% calcium cations of the total initial carboxyl groups reacted and from 10% to 40% free acid and wherein said salt has a bulk density of from 0.6 to 1.2 grams pe cubic centimeter and a specific surface area of from 0.6 to 2.5 square meters per gram. A denture stabilizing composition comprising a safe and adhesivel effective amount of at least two denture adhesive components, wherein on of said denture adhesive components is a lower alkyl vinyl ether-malei acid copolymer consisting essentially of the repeated structural unit: wherein R represents a C x to C 4 alkyl radical, preferably methyl, n is an integer greater than one representing the number of repeated occurrences of said structural unit in a molecule of said copolymer and n is large enough to characterize said copolymer as having a specific viscosity larger than 1.2, the specific viscosity being determined in methyl ethyl ketone at 25 β C and wherein said copolymer has a bulk density of from 0.3 to 1.2 grams per cubic centimeter and a specific surface area of from 0.5 to 2.5 square meters per gram. A denture stabilizing composition comprising a safe and adhesively effective amount of at least two denture adhesive components, wherein one of said denture adhesive components is the mixed partial salt of a lower alkyl vinyl ether-maleic acid copolymer consisting essentially of the repeated structural unit: wherein R represents a Cj to C 4 alkyl radical, preferably methyl, n is an integer greater than one representing the number of repeated occurrences of said structural unit in a molecule of said copolymer and n is large enough to characterize said copolymer as having a specific viscosity larger than 1.2, the specific viscosity being determined in methyl ethyl ketone at 25'C, said partial salts containing from 10% to 40% free acid, and as the cationic salt function from 0.1% to 85% of the total initial carboxyl groups reacted with one or more of a cationic salt functio selected from the group consisting of zinc cations, strontium cations sodium cations, calcium cations, magnesium cations, potassium cations an ammonium cations and mixtures thereof and wherein said copolymer has bulk density of from 0.3 to 1.2 grams per cubic centimeter and a specifi surface area of from 0.5 to 2.5 square meters per gram. 9. The partial salt of Claim 3 wherein said cationic salt function i selected from the group of zinc, strontium, calcium, and sodium cation and mixtures thereof and comprises: (a) from 0.1% to 65% zinc or strontium cations, preferably 2.5% to 30% zinc cations,; and (b) from 0.1% to 75% calcium cations or sodium cations, preferably fro 5% to 20% sodium cations or mixture thereof; and (c) from 40% to 70% calcium cations of the total initial carboxyl groups reacted and from 10% to 40% free acid and wherein said salt has a bulk density of from 0.6 to 1.2 grams pe cubic centimeter and a specific surface area of from 0.6 to 2.5 square meters per gram. 10. The denture stabilizing composition of any of the preceding Claims wherei said polymeric material is selected from the group consisting of natura gums, synthetic polymers, saccharide derivatives, cellulose derivatives and mixtures thereof and which further comprises from .01% to 5.0% o menthol, menthyl lactate, peppermint oil, spearmint oil, peppermint oil leaf alcohol, and paramenthane carboxyamides, and mixtures thereof.

Inventors: DHABHAR DADI JAMSHED, GOUNARIS MICHAEL CONSTANTINOS, GRUBBS DENNIS ROBERT, MACKAY BRUCE JOHN, DHABHAR, DADI, JAMSHED, GOUNARIS, MICHAEL, CONSTANTINOS, GRUBBS, DENNIS, ROBERT, MACKAY, BRUCE, JOHN
Applicants: RICHARDSON VICKS INC, RICHARDSON-VICKS INC.
Application year: 1991
Main classification: A61K6
IPC codes: A61C13, A61K6, C08F8