Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Including a second component containing structurally defined...
Reexamination Certificate
2002-02-14
2003-09-23
Le, H. Thi (Department: 1773)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Including a second component containing structurally defined...
C162S175000, C162S181500, C162S181600, C162S187000, C162S231000, C502S064000, C502S070000, C428S328000, C428S329000, C604S368000, C604S376000
Reexamination Certificate
active
06623848
ABSTRACT:
The invention relates to absorbents for water and aqueous liquids, which absorbents are based on water-swellable, yet water-insoluble polymers wherein cyclodextrin or cyclodextrin derivatives and zeolites high in silicon have been incorporated ionically, covalently and/or as a result of mechanical inclusion.
Commercially available superabsorbing polymers essentially are crosslinked polyacrylic acids, crosslinked starch/acrylic acid graft copolymers, crosslinked hydrolyzed starch/acrylonitrile graft copolymers, crosslinked poly(maleic anhydride-co-isobutylene), or mixtures of various of the above-mentioned crosslinked polymers, wherein the carboxylic groups have been-subjected to partial neutralization with sodium and/or potassium ions. Such polymers find use e.g. in hygiene articles capable of absorbing body fluids such as urine or menstrual fluid or in absorbent pads in packagings for foodstuffs where they absorb large amounts of aqueous liquids and body fluids such as urine or blood with swelling and formation of hydrogels. Furthermore, the absorbed amount of liquid must be retained under a pressure typical of use. During the further technical development of superabsorbing polymers, the pattern of requirements to be met by these products has changed significantly over the years.
To date, the development of superabsorbers has been forced particularly with respect to the amount of absorbed liquid and pressure stability. Such crosslinked polymer products based on monomers containing acid groups are obtained by using one or more primary crosslinkers and/or one or more secondary crosslinkers and exhibit a combination of properties, namely, high retention, high absorption under pressure, low solubles, rapid absorption of liquid, and high permeability in the swollen state, which has not been achieved so far. When used in hygiene articles, these crosslinked polymer products have the advantage that secreted fluids, once absorbed by the polymer product, can no longer contact the skin. Thus, skin lesions such as diaper dermatitis can largely be avoided. Such comfort can even be increased by absorbing malodorous compounds.
According to Römpp Chemie Lexikon, the content of urine components and thus, of malodorous compounds, is subject to physiological fluctuations; also, particular substances are secreted at concentrations varying within a daily period, so that more precise data on the urine composition invariably are related to the so-called 24 hour urine which, in a healthy adult, contains e.g. urea average 20 g), uric acid (0.5 g), creatinine (1.2 g), ammonia (0.5 g), amino acids (2 g), proteins (60 mg), reducing substances (0.5 g, about 70 mg of which are D-glucose or urine sugar), citric acid (0.5 g) and other organic acids, as well as certain vitamins (C, B
12
etc.). The following inorganic ions are present: Na
+
(5.9 g), K
+
(2.7 g), NH
4
+
(0.8 g), Ca
2+
(0.5 g), Mg
2+
(0.4 g); Cl
−
(8.9 g), PO
4
3−
(4.1 g), SO
4
−2
(2.4 g). The dry content is between 50 and 72 g. Inter alia, alkylfurans, ketones, lactones, pyrrole, allyl isothiocyanate, and dimethyl sulfone have been recognized as volatile components of urine. Most of the volatile components are molecules having a molar mass below about 1000 g/mol and a high vapor pressure.
Volatile components of urine have also been investigated by, inter alia, A. Zlatkis et al. (Anal. Chem. Vol. 45, 763ff.). It is also well-known that consumption of asparagus results in an increase of the concentration of organic sulfur-containing compounds in human urine (R. H. Waring, Xeno-biotika, Vol. 17, 1363ff.). In patients who are subject to specific diets and/or ingest specific medications, or in elderly individuals with decreasing kidney function, the urine may include malodorous substances. Patients suffering from urine incontinence have an increased secretion of ureases which convert the urea contained in urine, thereby liberating toxic ammonia. Also, a pathological change is well-known which is referred to as fish smell syndrome. It results from an increased secretion of quaternary ammonium compounds. Also, menstrual fluid may acquire an unpleasant odor. Among other things, this odor is produced by microbial degradation of secreted proteins. Typical odorous substances in menstrual fluid and the smells produced by degradation of blood components are not substantially different from the smell of components occurring in urine. In this case as well, low molecular weight compounds having a molar weight of less than 1000 g/mol are involved. Predominantly, nitrogen-containing heterocycles such as pyrrole, pyridine and derivatives thereof may be mentioned. Furthermore, those smells liberated by foodstuffs may be mentioned, e.g. the smell of fish (amines).
The odorous components in vaginal secretions and menstruation fluid have been investigated by G. Huggins and G. Preti (Clinical Obstetrics and Gynecology, Vol. 24, No. 2, June 1981, 355-377), where low molecular weight substances having a molar weight below 500 g/mol have been found. Fatty acids (e.g. butyric acid, isovaleric acid) and some aromatic compounds such as pyridine, indole and thymine may be emphasized, which particularly contribute to unpleasant odors. The amount of volatile fatty acids varies over the time period of the menstrual cycle (Human Vaginal Secretions: Volatile Fatty Acid Content, Richard P. Michael, R. W. Bonsall, Patricia Warner, Science, Dec. 27, 1974, 1217-1219). Amines have not been found in vaginal secretions and menstruation fluid. This is because the pH value of the secretion in a healthy female patient is in the acidic range where, at most, ammonium salts are present which are non-volatile. It is only in pathological conditions where proteins increasingly can be converted to amines by bacterial degradation, which may enter the vapor space in case of a simultaneous increase of the pH value.
Previous approaches of achieving an odor reduction in incontinence products and Ladies' hygiene products are based on reducing the concentration of free ammonia. Basically, there are two approaches to this end: preventing additional production of ammonia from urea degradation by suitable urease inhibitors (A. Norberg et al., Gerontology, 1984, 30, 261ff.), or by protonating free ammonia and binding thereof in the form of a carboxylate ammonium salt. This method is disadvantageous in that essentially, merely ammonia and other nitrogen-containing components can be controlled. Malodorous compounds lacking basic groups, e.g. thiols, are still capable of entering the vapor space.
It is well-known to those skilled in the art that certain interstitial molecules, also referred to as endohedral or concave molecules, are capable of incorporating other, mostly smaller, so-called guest molecules, thereby forming a host-guest complex. Such complex formation has an effect on the chemical and physical properties of both guest and host molecule. Cyclodextrins are formed during starch degradation by
Bacillus macerans
or
Bacillus circulans
under the action of cyclodextrin glycosyl transferase. They are comprised of 6, 7 or 8 glucose units &agr;-1,4-linked to form a ring (&agr;-, &bgr;- or &ggr;-cyclodextrins). They are capable of entrapping hydrophobic guest molecules in varying amounts up to saturation (“molecular encapsulation”), e.g. gases, alcohols or hydrocarbons. The use of cyclodextrins as host molecule is reported comprehensively in the work of J. Szejtli (Cyclodextrin Technology, Kluwer Academic Publishers, 1988).
Polymers containing cyclodextrin are well-known. Thus, the patent application EP 483,380 A1 describes cyclodextrin-containing polymers where aldehyde groups in a protected or unprotected form are introduced into the cyclodextrin to react with nucleophilic groups of the polymer to form covalent bonds.
Crosslinked, water-swellable, hydrophilic cyclodextrin bead polymers are known from U.S. Pat. No. 5,360,899, which polymers are produced using hydroxyalkylcyclodextrins and epichlorohydrin or polyepoxide type crosslinkers with su
Brehm Helmut
Harren Jorg
Issberner Jorg
Mertens Richard
Le H. Thi
Smith Moore LLP
Stockhausen GmbH & Co. KG
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