Steiger, Fred Harold (East Brunswick, NJ)
Siragusa, Judith Ann (Hopewell, NJ)

05/403749

03/04/1975

10/05/1973

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Personal Products Company (Milltown, NJ)

604/359

604/375

A61F13/00; A61F13/15; A61L15/28; A61L15/16; A61F13/18; A61F13/00

128/284,285,29R,296,156

3269964	Water dispersible form of dialdehyde polysaccharides and process therefor	August 1966	Curtis
3340875	Deodorized sanitary napkin	September 1967	Dudley et al.

Laudenslager, Lucie H.

Lipow, Jason

What is claimed is

1. In a product for absorbing body fluids comprising an absorbent body and having deodorizing properties, the improvement wherein said product comprises aldehyde polysaccharide having amine deodorizing properties.

2. The product of claim 1 wherein said aldehyde polysaccharide has a percent conversion to the aldehyde form of at least 5 percent.

3. The product of claim 2 wherein said percent conversion is at least about 30 percent.

4. The product of claim 2 wherein said absorbent body comprises at least about 5 percent by weight of said aldehyde polysaccharide.

5. The product of claim 4 wherein said absorbent body comprises at least about 25 percent by weight of said aldehyde polysaccharide.

6. The product of claim 1 wherein at least 65 percent by weight of said aldehyde polysaccharide is distributed in the top half, by weight, of said absorbent body.

7. The product of claim 6 wherein at least 50 percent by weight of said aldehyde polysaccharide is distributed in the top one-third by weight of said absorbent body.

8. The product of claim 1 wherein said aldehyde polysaccharide comprises aldehyde cellulose fibers.

9. The product of claim 8 wherein said aldehyde cellulose fibers have a percent conversion to the aldehyde form of at least 5 percent and comprise at least about 5 percent by weight of said absorbent body.

10. The product of claim 9 wherein said aldehyde cellulose fibers have a percent conversion of at least about 30 percent.

11. The product of claim 1 wherein said aldehyde polysaccharide comprises a starch.

12. The product of claim 11 wherein said aldehyde starch has a percent conversion of at least 5 percent and comprises at least about 5 percent by weight of said absorbent body.

13. The product of claim 12 wherein said aldehyde starch has a percent conversion of at least about 30 percent.

14. The product of claim 1 wherein said aldehyde polysaccharide is in the form of alloy fibers.

15. The product of claim 1 further comprising an alkali salt.

16. The product of claim 15 wherein said alkali salt is present in quantities of about 0.05 grams per gram of total absorbent body.

BACKGROUND OF THE INVENTION

This invention is directed toward absorbent products and more particularly to such products as wound dressings, diapers or catamenial dressings which are designed to absorb fluids discharged from the body and are to be worn for a substantial period of time.

The art has long been devoted to finding a solution to the problem of embarrassing and unpleasant odors arising from the use of diapers and dressings. The body fluids absorbed by these dressings and, in particular, by catamenial dressings, contain various organic materials such as mucus, blood and blood derivatives including hemoglobin, fibrin, blood albumin and serum. When in use, these dressings provide an ideal environment for pathogenic micro-organisms such as streptococca, enterococci, diptheroids and coliform bacilli which are normally present in body orifices such as the vagina. These organisms cause the formation of decomposition products, and in particular, cause the formation of amine compounds, a major cause of embarrassing and unpleasant odor.

While it is already known that certain substances or deodorizers are capable of either inhibiting the growth of micro-organisms or masking the odor of the decomposition products resulting from these micro-organisms, the choice of deodorizers, useable in products such as sanitary napkins, tampons and diapers, is severely limited in that many such substances have undesirable effects and cause sensitization, irritation and allergenic reactions, particularly if used over an extended period of time. Further, a great many deodorizers have been found to be unstable and lose their effectiveness in storage.

Of the therefore limited choice of substances useful as deodorizers in products of this nature, the art has been still further limited in that it has heretofore been difficult to incorporate deodorizing substances into the dressings. Diapers and catamenial dressings all generally comprise an absorbent pad of loosely associated fibrous materials such as comminuted woodpulp fibers, cotton linters, rayon fibers, cotton staple, synthetic absorbent fibers and the like. It has been found to be extremely difficult to incorporate and maintain deodorizers, heretofore generally in the form of powders, within the absorbent pad of the dressings without resorting to extremely elaborate procedures which are incompatible with the high speed manufacturing and packaging techniques associated with these products. For example, blending deodorizers into the supply of fibrous material prior to the forming of the individual absorbent pad has created difficulties in that the deodorizers tend to settle causing a maldistribution which can frequently result in pads being formed which contain too much or too little deodorizer. On the other hand, incorporation of the deodorizers into the pad after their formation has been unsatisfactory in that much of the deodorizer is lost by the shaking, rubbing and the other handling which this product is subject to in subsequent manufacturing, packing and storage procedures as well as in use. Elaborate methods have been devised to obviate those problems. For example, it has been proposed that the deodorizer be dispersed in a liquid along with a dispersed resin binder. The fibers of the formed absorbent pad may be treated with the dispersion and then the liquid may be removed leaving the deodorizer held in place by the resin binder.

While such a method is effective in insuring that the deodorizer will be uniformly distributed and maintained within or upon the absorbent body, the method is inconvenient and expensive and additionally, it has been found that the resin binder, to an extent, interferes with the absorptive properties of the dressing.

Accordingly, there is a need for an effective deodorizing dressing which overcomes the drawbacks of prior methods.

SUMMARY OF THE INVENTION

In accordance with this present invention, a dressing for absorbing body fluids comprising an absorbent pad is provided which greatly reduces the unpleasant odor associated with the use of these products without the need for incorporating non-compatible, non-absorbent deodorizing materials into the absorbent pad. It has been discovered that the aldehydic polysaccharides when incorporated into the absorbent pad exhibit deodorizing properties and, in particular, greatly reduce the odor intensity of amine compounds, believed to be a chief cause of odor in diapers, wound dressings and catamenial products. Specifically, polysaccharides, such as starch and cellulose, may be chemically modified by attacking the hydroxyl groups in a portion of the anhydrous glucose units of these polymers with an oxidizing agent to convert the hydroxyl group to aldehyde groups, the products of the oxidation hereinafter being termed "aldehyde polysaccharides." It has been discovered that these polysaccharides can be provided in the form of absorbent fibers and so can obviate the problems associated with prior deodorizers in that they can conveniently and effectively be incorporated into the dressings of this invention. For example, fibrous cellulose may be oxidized to the aldehyde form and will, in all important respects, exhibit the properties of the unoxidized fibers with the exception that the oxidized fibers will be effective deodorizers. In another example, starch may be oxidized and incorporated into a viscose rayon spinning solution. In this manner, an alloy fiber having deodorizing properties may be provided. Again, the resulting fibers will have the physical characteristic of non-deodorizing fibers now commonly used in the dressings of this invention and so will be easily incorporated into these dressings in a manner compatible with current manufacturing procedures.

It has been discovered that if only a small portion of the fibers of a dressing pad comprise aldehyde polysaccharide, the odor intensity of amine compounds absorbed onto the pad is significantly reduced. The capacity for reducing the odor intensities of amines is a function of the percent conversion of the polysaccharide to the aldehyde form as well as the quantity of converted polysaccharide incorporated into the absorbent pad. In general, these parameters should be chosen to produce an odor reduction of at least about 30 percent based on an objective organoleptic evaluation test such as the one described hereinafter, using a model odorant such as dimethylamine. As an example, a pad comprising as little as 5 percent by weight of the aldehyde polysaccharide fibers (i.e., the weight percent of the fibers comprising polysaccharide treated to convert a portion of the polymers to the aldehyde form) will reduce the odor intensity of dimethylamine by almost 50 percent. A reduction of 90 percent may be accomplished by increasing the aldehyde polysaccharide fiber content of the pad to 15 percent by weight. The percent of conversion of hydroxyl groups on the polymer chain may vary widely and still produce an effective deodorizer. As used herein, the term "percent conversion" is defined as the percentage of hydroxyl groups converted to the aldehyde form based on the total number of hydroxyl groups on the unconverted polysaccharide chain.

A polysaccharide having a percentage conversion as low as 5 percent can be effective as a deodorizer. From a practical point of view, however, little additional cost is involved in converting polysaccharides to percentage conversions of about 30-60 percent with concomitant increased deodorizing effectivity. In the case of cellulose fibers, a percent conversion of more than 60 percent generally adversely affects such product-related properties as fiber grindability, product uniformity, and web strength and should be avoided where these properties are important. On the other hand, starch may be converted beyond the 60 percent level without such adverse effects.

It has further been discovered that it is advantageous to place the aldehyde polysaccharide fibers in greatest concentrations at those portions of the absorbent pad where the fluid being absorbed first enters (hereinafter referred to as the top of the pad). In this way, the efficiency of the deodorizer is greatly enhanced. Preferably, at least 65 percent by weight of the aldehyde polysaccharide fibers should be distributed in the top half of the pad and still more preferably, at least 50 percent should be distributed in the top third of the pad.

DETAILED DESCRIPTION OF THE INVENTION

The aldehyde polysaccharide, incorporated into a dressing in accordance with this invention, may be made by starting with a wide variety of natural and synthetic polysaccharide materials such as, for example, starch and such cellulosics as wood pulp, rayon, cotton, flax and the like. Preferably, the starting material chosen is one which is in the form of absorbent fibers or can be extruded or otherwise shaped into this form and will be compatible with the manufacturing and the use of the dressing when incorporated with additional absorbent material in forming an absorbent pad.

Polysaccharide, from any of these sources, may be oxidized to the herein prescribed aldehyde form by the action of an oxidizing agent attacking the hydroxyl groups on the anhydrous glucose units of the polymer chain. For example, when sodium periodate is chosen as the oxidizing agent, the vicinal hydroxyl groups in the anhydrous glucose unit are attacked to form two aldehyde groups, the resulting product having the structure: ##SPC1##

The reaction of cellulose with sodium periodate may be carried out in accordance with the teachings of U.S. Pat. No. 3,086,969, issued to James E. Slager on Apr. 23, 1963. The cellulose is contacted and allowed to react with a periodic acid solution, the percent conversion of hydroxyl groups to the aldehyde form being controlled by selecting the proper molar ratio of the reactants and the time for conducting the reaction. For example, at reaction temperatures of about 25°-40°C., the reaction time may vary from about three to about five hours. While it is preferred that the oxidizing agent by sodium periodate, it will be understood that various other agents may be used to produce an effective form of aldehyde polysaccharide. For example, such diverse oxidizing agents as chromic acid, alkaline hypocholorite, hydrogen peroxide or even ozone may be employed.

Irrespective of which method is used to oxidize the hydroxyl groups on the polymer chain, the extent of the reaction may be controlled to provide the preferred conversions prescribed herein by choosing the proper molar ratio of reactants and limiting the time of reaction, in accordance with methods well-known in the art. It has been discovered that a percent conversion of as little as 5 percent, when used in a pad, is effective as a deodorizer for obnoxious odors resulting from amine compounds. Preferably, a percent conversion of at least 30 percent should be used.

When even small amounts of aldehyde polysaccharide having the above prescribed percent conversions are combined with the other absorbent materials in the pad, a significant deodorizing effect is evidenced with respect to amines. For example, while as little as 5 percent by weight percent will produce this result, it is preferable to provide, in such products as the wound dressings, diapers and catamenial dressings at least about 10 percent weight of the prescribed aldehyde polysaccharide and preferably at least 25 percent.

The dressings of this invention are highly effective in reducing odors caused by a wide variety of amines which have been found to be present in such dressings such as, for example, mono-, or di- and trimethyl amines; mono-, di- and tri-ethyl amines; and mono-, di and tripropyl amines, in addition to the more complex, cyclic amines such as indole and skatole (methyl indole).

The specific reason for the effectiveness of the dressings of this invention is not yet known. It may be speculated that the aldehyde groups react with the primary amines in one of several ways. There could be a mono-adduct formation reaction, ##SPC2##

the formation of an adduct with two units where the aldehyde groups are on the same or different chains, ##SPC3##

the formation of a Schiff base type compound, ##SPC4##

In a similar fashion, secondary amines may react to form an adduct, ##SPC5##

In the preceding notation, R represents the polysaccharide chain and R' and R" represent alkyl or heterocyclic structures of the amines.

All of the preceding reactions are based on the presence of labile hydrogen on the amine. Inasmuch as there is no labile hydrogen group on tertiary amines, these reactions are completely unsatisfactory in explaining the observed effectiveness of the products of this invention with respect to such tertiary amines.

In accordance with this invention, the aldehyde polysaccharide fibers are incorporated in the absorbent pads used in such products as wound dressings, diapers, sanitary napkins and tampons. Generally, the absorbent pads for each of these products are formed from a bulk supply of absorbent fluff such as ground wood pulp board, regenerated cellulosic fibers, or the like. A small portion of this bulk fluff may comprise aldehyde polysaccharide, such as, for example, cellulose fibers which have been oxidized to the aldehyde form. This oxidizing treatment does not significantly alter the physical characteristics of the fibers and so the treated fibers may easily be uniformly blended with untreated fibers, the mixing being essentially that of homogeneous material and hence, a uniform mixture is easily attainable. Further, because the modified fibers are physically the same as the unmodified fibers, the problems of retention in the absorbent pads, heretofore associated with other deodorizers, is completely obviated; the modified fibers are entangled and held in place with the remaining fibers in the pad.

Alternatively, in the case where regenerated cellulose fibers are used, the aldehyde polysaccharide may be incorporated directly into the viscose dope prior to spinning the regenerated cellulose fibers through the spinnerettes. U.S. Pat. No. 2,796,656 issued to Joseph W. Schappel, et al., on June 25, 1957, describes a process for forming so called "alloy fibers" incorporating substituted cellulose such as carboxymethyl cellulose polymers into the regenerated cellulose fibers. In a like manner, the aldehyde polysaccharides of this invention, e.g., aldehyde cellulose and aldehyde starch may be incorporated to form an alloy fiber having deodorizing properties. These alloy fibers may be used alone or together with other non-deodorizing fibers in the absorbent pad.

While an effective dressing can be produced by distributing the aldehyde polysaccharide uniformly throughout the absorbent pad, it has been discovered that, particularly with thick pads, the use of the aldehyde polysaccharide is enhanced by placing the same in that portion of the pad which first contacts the body discharge (i.e., the top portion). In the case of sanitary napkins and diapers, this is the portion from which the odorants are most likely to evolve during use. For example, a pad uniformly distributed with a quantity of a specific aldehyde cellulose fiber of about 25 percent by weight of the total pad reduces the odor of a model amine odorant by 85 percent, in accordance with the organoleptic testing method herein described. In contrast with this, a pad comprising only 5 percent of the same aldehyde cellulose, distributed uniformly in only the top third of the pad (the portion on which the odorant is first introduced) reduces the odor level by 56 percent, i.e., one-fifth the deodorant accomplishes more than about two-thirds of the reduction. It is important to note, in this connection that this result is accomplished even though the odorant is first applied and then allowed to equilibrate on the pad so that it is thoroughly and uniformly distributed throughout the pad before organoleptic evaluations are made. In general, it has been found that with a given quantity of the deodorizer, a substantial increase in deodorization may be achieved by distributing the aldehyde polysaccharide fibers so that at least 65 percent by weight of such fibers (based on total weight of such fibers present in the pad) are distributed in the top half of the pad. Preferably, at least 50 percent should be distributed in the top third of the pad.

Absorbent pads, made in accordance with the teachings of the invention, are organoleptically evaluated and the examples which follow, illustrate the advantages which accrue. For the purposes of these examples, an evaluation procedure, hereinafter referred to as the Modified Ratio Scale Organoleptic Evaluation Method, is employed.

THE MODIFIED RATIO SCALE ORGANOLEPTIC EVALUATION METHOD

This method is devised so that data obtained from an organoleptic appraisal panel may produce an evaluation of a sample characterized as an absolute value for odor intensity. Thus, not only can the difference between two samples of an odorant placed in different environments (e.g., on a pad with and without deodorizer) be detected, but further, the evaluation will indicate, quantitatively, as to whether the odor intensities of the samples are strong or weak. For example, one sample may contain a deodorizer which is many times as effective as that contained in a second sample. This notwithstanding, both deodorizers may only produce a small decrease in the odor intensity, all of which is indicated by the subject evaluation method.

The first step in this method is to determine the threshold concentration of the odorant. The method used is described by Fred H. Steiger in Chemical Technology, Volume 1, p. 225, April, 1971, wherein the determination of the odor threshold concentration for ethylamine is described, applying the Weibull distribution function. Generally, this procedure requires the gathering of organoleptic data from a panel presented with a series of samples containing odorant in increasing concentrations in order to determine the concentration level at which an arbitrary percentage of the panelists can detect the odor. For the purposes of the current evaluation that arbitrary percentage is chosen as the cumulative 50 percent level. As so determined, the threshold concentration of the odorant is specific to the odorant and the conditions of the sampling procedure.

The method employed herein for panel evaluation is to present each panelist with a series of samples, in a sampling apparatus which consists of an opaque, one pint, polyethylene Mason jar having a polyethylene screw cap fitted onto its neck. The jar is internally lined with a polyethylene bag and a Buchner funnel is fitted above the cap, with the narrow outlet portion of the funnel, below the filter plate of the funnel, extending through the cap and into the lined jar. A sample is placed in the jar, the jar is capped with the Buchner funnel fitted in place and a watch glass is placed across the wide inlet portion of the funnel. The sample is then allowed to equilibrate for one hour at ambient conditions. For the purpose of the threshold determination, the samples each comprise a specific concentration of the odorant in a water solution, a total of 3 ml. of solution being placed in the jar. A panel of about 30 women are presented with a series of equilibrated samples of increasing concentration and, starting with a sample at zero concentration (water only), are asked to report the first sample having a detectable odor. The panelists are instructed to sniff each sample in turn, pausing 30 seconds between samplings. The accumulated data is organized to establish the cumulative percentage of the panel which detects an odor at each concentration level corresponding to each sample. The data, so organized, is plotted as described in the aforementioned Steiger article on Weibull Probability Paper with the concentration as the abscissa and the cumulative percentage of the panel as the ordinate. The concentration at 50 percent is then taken as the threshold concentration.

Having established the threshold value, the Modified Ratio Scale Method is applied by preparing a master curve. Using the same testing apparatus, a series of samples are prepared and presented to the panel wherein the concentrations of odorant are in multiples of the threshold concentration. One of these samples must be 20 times the threshold concentration. In accordance with the standard method of Ratio Scaling, each panelist is asked to evaluate the set of samples before her and to assign a value to the odor intensity of each sample in proportion to the intensity of the other samples. The panelists are free to choose whatever scale they wish. For example, a panelist may assign 10 to the strongest sample. A sample having half the intensity, in accordance with this panelist's evaluation, would then be assigned a value of 5. The accumulated data then consists of a series of evaluations at each multiple of threshold concentration for each panelist, each series being based upon the individual panelist's scale. Arbitrarily, a ratio scale value of 100 is assigned to the sample concentration of 20 times threshold concentration. Each of the panelists' evaluations are then proportioned to bring their individual scales to the basis of 100 for 20 times threshold concentration. For example, the evaluations of a panelist assigning a value of 10 to a first sample having a concentration of 20 times threshold concentration and 5 to a second sample having 4 times threshold concentration will be proportioned to show, for that panelist, a value of 100 for the first sample and a value of 50 for the second sample. The data is now organized so that, for each sample corresponding to a specific multiple of the threshold concentration, there is a series of Ratio Values, all on the same scale (20 times Threshold Concentration = 100) corresponding to each panelist's evaluation of this sample. The geometric means of the ratio values for each sample is calculated and that value is taken as the Ratio Value for that multiple of threshold concentration. When the log of the Ratio Value is plotted, as the ordinate, against the log of the multiple of threshold concentration, a straight line, fitted to the data points between 3 to 20 times threshold concentration gives an excellent correlation.

It has been discovered that irrespective of which amine odorant is tested, when a threshold concentration is determined for that specific odorant and the method of constructing a Master Curve as described above is followed, the resulting Master Curves are superimposable between multiples of threshold concentration of about 3 to about 20.

Interestingly, the curve obtained in this way for a chemically dissimilar material (isobutyric acid) also was superimposable on the Master Curve for the amines.

The Master Curve may now be used to evaluate the odor intensity of any odorant when placed in any environment such as, for example, on a pad of untreated cellulosic fibers or on a pad of fibers containing deodorizing material and, in addition to obtaining comparisons between the relative intensity of the samples tested, an absolute measure of the intensity of each sample may be obtained. To do this, the panel is presented with a series of samples, one of which is a standard sample consisting of a known concentration of the odorant being tested in an environment identical to that used in producing the Master Curve. Preferably, this standard sample is chosen as having 20 times the threshold concentration and hence, a Ratio Value of 100 on the Master Curve. The panelists are again asked to evaluate the series of samples using whatever scale they choose. Based on the value which each panelist gives to the intensity of the standard sample, all other values given by the panelist are proportioned so as to be consistent with the rating of the standard sample, e.g., a panelist assigning a value of 50 to the standard sample and 5 to a second sample of unknown intensity will have these values proportioned so the standard will be given a Ratio Value of 100 and the unknown sample given a Ratio Value of 10. By referring to the Master Curve, it can be determined that the panelist's now proportioned Ratio Value of 10 for the second sample is equivalent to an odor intensity of a certain number of multiples of threshold concentration as read from the Master Curve, e.g., 1.2. Said in other words, the odor intensity of the sample of unknown intensity, in the test environment, is the same as a sample having an odorant concentration of 1.2 times the threshold concentration in the standard environment.

The following examples illustrate the advantages of this invention.

EXAMPLE I

Water washed, three denier rayon is reacted in a solution of 0.5 molar sodium metaperiodate, the solution having a pH of 2. The reaction occurs at room temperature and is allowed to continue for 6 hours. Oxidized rayon fibers are obtained and are analyzed by the method of J. J. Willard and R. F. Schwenker, Jr., Textile Research Journal, 35, p. 564 (June, 1965), indicating a 20 percent conversion of the hydroxyl groups of the anhydrous glucose units to the aldehyde form. A second sample is prepared allowing the rayon to react for 24 hours. Analysis indicates a 34 percent conversion.

Threshold concentrations are determined by a panel of 17 individuals using ethylamine as the odorant and using the procedures and apparatus described above. In each case, three milliliters of a water solution of ethylamine at the concentrations shown in the table below are introduced into the sampling apparatus. A first series of samples contain only the ethylamine solution, a second contain 5 grams of unoxidized water washed rayon fibers, as a control. Third and fourth series of samples contain 5 grams of the 20 and 34 percent converted rayon fibers, respectively. Each series is presented to the panelists in order of concentration and the panelists are asked to identify the first sample which has a detectable odor. The order of presentation of each series is randomized.

The results are reported in Table I along with the cumulative 50 percent level as calculated by use of the Weibull distribution function, referenced above.

TABLE I ____________________________________________________________ ______________ PERCENTAGE OF PANEL DETECTING ODOR Solution Water Washed 20% Converted 34% Converted Only Rayon Control Rayon Rayon Concentration of Ethylamine (grams/ml × 10 ⁴ ) ____________________________________________________________ ______________ 0.00 0 0 0 0 0.88 0 0 0 0 1.8 0 6 6 12 3.5 18 12 18 12 7.0 35 47 18 12 14.0 82 88 29 24 28.0 88 100 29 24 56.0 100 100 35 24 112.0 100 100 71 35 224.0 100 100 94 53 Greater than 224 100 100 100 100 Calculated Threshold Concentration: 9.4 7.2 68 250 ____________________________________________________________ ______________

As the above table indicates, the water solution and the untreated rayon control are essentially organoleptic equivalents showing a 50 percent threshold ethylamine concentration of between 7.2 and 9.4 × 10 ^-4 gm/ml. In dramatic contrast, the threshold concentration for samples containing 20 and 34 percent converted aldehyde rayon is increased to 68 × 10 ^-4 and 250 × 10 ^-4 gm/ml, respectively. That is to say, the presence of the aldehyde rayon has so depressed the odor intensity of the ethylamine, that the cumulative 50 percent threshold level reported is about 8 times that of the controls in one case and 30 times in the other.

The Modified Ratio Scale Organoleptical Evaluation method is used to illustrate the effectiveness of aldehyde cellulose as a deodorizer when combined with wood pulp in an absorbent pad. A panel of 35 individuals is used and the standard environment consists of 3 ml of odorant solution applied to a 2.0 gram pad of wood pulp. For purposes of this example, and the following examples, the multiples of threshold concentration of the solution applied to the wood pulp pad will be referred to as the Applied Odor Units. A Master Curve is prepared, as described above, and the values reported by the panelists are averaged for each sample tested, using the geometric mean and put on a standard basis using this Master Curve. This value is referred to as the Reported Odor Units, i.e., the odor intensity which is equivalent to the intensity of a sample in the standard environment, at the concentration of the odorant equal to the Reported Odor Units times the threshold concentration.

EXAMPLE II

This example illustrates the effects of varying the percent conversion of aldehyde cellulose, uniformly distributed in an absorbent pad of untreated wood pulp. The treated cellulose consists of fibrous wood pulp which is oxidized to the extent indicated in the Table II below using periodic acid as the oxidizing agent. Each of the samples tested consists of 3 milliliters of the odorant solution applied to a 2 gram pad consisting of 1 gram of the aldehyde cellulose and 1 gram of wood pulp at the percent conversion indicated in Table II, below. Triethylamine is used as the odorant in two tests, applying two different quantities of odorant, and dimethylamine is used in a third test. The results are reported in Table II.

TABLE II ____________________________________________________________ ______________ Applied Odor Units Reported Odor Units Odorant 2 gm Untreated 1 gm Untreated 1 gm Untreated 1 gm Untreated 1 gm Untreated Pulp Pulp Pulp Pulp Pulp 1 gm 7% Con- 1 gm 40% Con- 1 gm 54% Con- 1 gm 57% Con- verted Alde- verted Alde- verted Alde- verted Alde- hyde Cellulose hyde Cellulose hyde Cellulose hyde Cellulose ____________________________________________________________ ______________ Triethylamine 20 12 4 3 3 Triethylamine 43 36 15 8 6 Dimethylamine 124 78 42 28 10 ____________________________________________________________ ______________

As Table II reveals, a pad comprising 50 percent by weight of aldehyde cellulose at the relatively low percent conversion of 7 percent will substantially reduce the odor intensity of the odorants tested. This effect is dramatically increased as the percent conversion is increased so that at a percent conversion of 57, the odor intensity is reduced down to a value of from about 8 to 15 percent of the standard value. It should be pointed out that the method of evaluating the panelists' data as used throughout this and the following examples is less reproducible at the lower odor units of 5 or less, which values approach the threshold for a number of the panelists.

EXAMPLE III

This example illustrates the effect of varying the applied odor intensity on an absorbent pad having a quantity of aldehyde cellulose of a constant percentage conversion. The absorbent pads tested each consist of 0.5 grams of aldehyde cellulose having a percentage conversion of 44 percent, uniformly blended with 1.5 gm of wood pulp. The standard sample upon which the value for applied odor units is based is the same as that of the preceding example. The odorant used is triethylamine. The results are reported in Table III below:

Table III ______________________________________ Applied Odor Units Reported Odor Units ______________________________________ 6 3 12 5 20 6 43 25 99 52 ______________________________________

As Table III indicates, the aldehyde wood pulp blend tested generally shows a relatively constant percent reduction in the odor intensity of the triethylamine, irrespective of the level of odor intensity, the reduced intensity varying from 30 to 58 percent of the standard.

EXAMPLE IV

This example illustrates the effect of placement of the aldehyde pulp in the absorbent pad. Four types of pads are prepared all having a total of 0.34 gms of 57 percent converted aldehyde cellulose and 1.66 grams of wood pulp. The pads were made up of three layers, each of which had fibers uniformly distributed therethrough in accordance with the distribution shown in Table IV below. The samples are placed in the sampling apparatus and three milliliters of a solution of dimethylamine is pipetted onto the top surface of each sample, the solution having a concentration, based on the same standard as in the preceding examples, of 110 odor units. After allowing the samples to equilibrate, they are presented to the panel and evaluated in accordance with the methods described herein. The results are reported in Table IV.

TABLE IV ____________________________________________________________ ______________ SAMPLE DISTRIBUTION REPORTED ODOR UNITS ____________________________________________________________ ______________ TOP LAYER MIDDLE LAYER BOTTOM LAYER 1 0.34 gms. alde- 0.66 gms. wood 0.66 gms. wood hyde cellulose pulp pulp 14 0.34 gms. wood pulp 2 0.66 gms. wood 0.34 gms. alde- 0.66 gms. wood pulp hyde cellulose pulp 30 0.34 gms. wood pulp 3 0.66 gms. wood 0.66 gms. wood 0.34 gms. alde- pulp pulp hyde cellulose 49 0.34 gms. wood pulp 4 0.11 gms. alde- 0.11 gms. alde- 0.11 gms alde- hyde cellulose hyde cellulose hyde cellulose 25 0.55 gms. wood 0.55 gms. wood 0.55 gms. wood pulp pulp pulp ____________________________________________________________ ______________

An examination of Table IV indicates that the best results are obtained when the aldehyde cellulose is located close to the top, i.e., the portion of the absorbent pad that first absorbs the odorant (sample 1) and the worst results are obtained with the aldehyde cellulose located close to the bottom (sample 3). Intermediate results are obtained from the two additional alternatives; sample 2, wherein the aldehyde cellulose is concentrated in the middle layer; and sample 4, wherein the aldehyde cellulose is uniformly distributed throughout the pad.

EXAMPLE V

A series of pairs of fluff pad samples are prepared; the first of the pair, a standard sample, consisting of 100 percent wood pulp and the second consisting of 0.5 grams of 57 percent converted aldehyde cellulose fibers blended with 1.5 grams of wood pulp. Samples of menstrual fluids are collected and pooled and three milliliter aliquots are pipetted onto each of the two sample pads in the series. The samples are given to a panel for evaluation, the results of which are reported below in Table V. The odor level resulting from each standard sample in the series is determined from the Master Curve by comparison with a sample containing dimethylamine having an odor intensity of 20 times threshold and the value so determined is referred to in the following Table V as the Applied Odor Units.

TABLE V ______________________________________ Applied Odor Units Reported Odor Units 0.5 gm. Aldehyde Cellulose (57%) 2 gms. Untreated Pulp 1.5 gm. Untreated Wood Pulp ______________________________________ 20 10 24 9 13 7 ______________________________________

As the above table indicates, a substantial reduction in the odor intensity is realized.

It is recognized that while amines are a chief source of the unpleasant odor associated with body fluids, such as for example, menstrual fluid, other compounds are present in such fluids. The odor intensity of these compounds may not be affected by aldehyde cellulose. One class of such compounds are the fatty acids such as, for example, butyric, isobutyric, valeric, and isovaleric acids. Accordingly, in another aspect of this invention, a small quantity of an alkaline salt is incorporated into the absorbent pad. Such alkaline salts as sodium carbonate and sodium bicarbonate may be used in quantities of about 0.05 gms. per gram of total absorbent pad and preferably about 0.1 gram/gram. To illustrate the added effects of this combination, the following example is given:

EXAMPLE VI

A 3 ml. sample of menstrual fluid having a particularly low pH of less than 6.7 is chosen and applied to the standard 2 gram untreated wood pulp pad. After aging, the odor corresponds to 30 odor units. Three ml aliquots from the same menstrual fluid source are applied to three sample pads consisting of 1.5 gms. of untreated wood pulp and 0.5 gms. of 57 percent converted aldehyde cellulose fibers; 2.0 gms. of untreated pulp on the surface of which is spread 0.1 gms. of sodium bicarbonate in powdered form; and 1.5 gms. of untreated pulp, 0.5 gms. of 57 percent converted aldehyde cellulose fibers and 0.1 gms. of sodium bicarbonate. The samples are evaluated by a panel using the methods described in the previous example. The results are reported in Table VI.

TABLE VI ____________________________________________________________ ______________ Applied Odor Units REPORTED ODOR UNITS 2.0 gms Untreated 1.5 gms Untreated Pulp 2.0 gms Untreated Pulp 1.5 gms Untreated Pulp Wood Pulp 0.5 gms 57% Aldehyde 0.1 gms NaHCO ₃ 0.5 gms 57% Aldehyde Cellulose Cellulose 0.1 gms NaHCO ____________________________________________________________ ______________ 3 30 24 15 3 ____________________________________________________________ ______________

As is illustrated in the foregoing table, the odor intensity of this selectively acidic sampling of menstrual fluid was substantially but only moderately affected by the inclusion of aldehyde cellulose. A greater reduction was accomplished by using NaHCO ₃ alone. The combination of NaHCO ₃ and aldehyde cellulose produce still greater reductions than the aforementioned systems, this greater reduction surprisingly being more effective than the sum of the individual reductions.