CA1163418A - Processes for making novel aluminum chlorhydroxide complexes - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A process for substantially improving the antiperspirant efficacy of aluminum chlorhydroxide, the process comprising aging, at a temperature below 100°C, the aluminum chlorhydroxide in an aqueous medium, at a concentration of from 5 to 40 weight percent, until the aluminum chlorhydroxide comprises at least 45 weight percent of an AlC' group of complexes. The AlC' group of complexes being characterized by having a diffusion constant in gel permeation chromatography within that range generally found for the Alb group of complexes, by exhibiting a complexing rate in the ferron test in the range of the AlC group of complexes, of at least about three days for completion of the reaction, and by at least 98 weight percent of the molecules °
within the AlC' group of complexes being less than 100 A in size in aqueous solutions.

Description

1 ~ 1 8 Aluminum chlorhydrates have long been used as antl~
perspirants. Generally such chlorhydrates in waker are complexes made up of rnixtures of polymeric species of various si~es and molecular structures. The aluminum chlorhydrates which have been found most useful as antiperspirants may be represented by the empirical formula:

A12(OH)5Cl In the past, aluminum hydroxyl polymers which are related to such aluminum chlorhydrates have been shown to be made up of three broad basic groups by spectrophotometrically following their complexing rates with 8-hydroxy-7-iodo-5-quin-olinesulfonic acid (ferron). Such basic groups have been referred to as Al , Al , and Al . The first group, Al has the fastest complexing rate (almost instan-taneously); the Alb group has an intermediate complexing rate (the reaction is complete in abdut an hour); and the AlC group has the slowest rate (generally the reaction takes a matter of days). It is known that aluminum chlorhydrates exhibit a similar phenomenon when reacted with ferron. For convenience the fastest reacting group within the aluminum chlorhydrate complexes may be referred to as Ala, the intermediate reacting group as Al and the slowest group as AlC. It is also known that when aqueous solutions of aluminum chlorhydrates are subjected to gel per-meation chromatography the three groups exhibit different retention times. The Al group has the longest retention time which is indicative that it is made up of the lowest molecular mg/~ - 2 -~ . ...
~' -` l J 6 ~ 3 size materials; the Alb group has an intermediate retention time, indicating it comprises complexes of intermediate molecular size and the AlC group has the shortest retention time indicating that it is made up of the highest molecular size complexes.
In the present invention it has been found that there is a further group of complexes within aluminum chlor-hydrates which heretofore hasn't been identified or recognized and which is more ef~icacious than the other groups heretofore characterized, Such more efficacious group of complexes, which for convenience may be referred to as AlC , is present in amounts of about 10 to 30% by weight in aluminum chlorhydrates presently available, although its presence has not been recognized or appreciated up to now. It has been further found that aluminum chlorhydrates can be modified or produced so as to contain a substantially higher amount of such more efficacious AlC group and accordingly the chlorhydrates so modified or produced are novel compositions of matter.
Generally, the aluminum chlorhydrates of this inv~ntion can be distinguished from known aluminum chlorhydrates in that they contain at least 45% by weight, preferably 60% and more preferably at least 70% of the AlC group of complexes.
According to the process aspect of this invention there is provided a process for substantially improving the antiperspirant efficacy of aluminum chlorhydroxidel the process comprising aging, at a temperature below 100C, the aluminum chlorhydroxide in an aqueous medium, at a concentration of from 5 to 40 weight percent, until the aluminum chlorhydroxide comprises at least 45 weight percent of an Al group of complexes, ~ 3 -1 1 63~

the AlC group of complexes being characterized by haviny a diffusion constant in yel permeation chromatography within that range gènerally found for the Alb group of co~plexes~ by exhibi~ing a complexing xate in the ferron test in the range of the AlC group of complexes, of at least about khree days for completion of the reaction~ and by at least 98 weight percent of the molecules within -the AlC group of complexes being less than 100 A in size in aqueous solutionsO
Even with the advanced analytical techniques avail-able today it is still not possible to determine the structure of aluminum chlorhydrate complexesO Accordingly, in defining the newly discove.red ~lc group of complexes it is necessary to ,!`'~ - 3a -~ i `

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resort to empirical procedures. sroadly, the new A] complex can be defined by its diffusion constant in gel permeation chromatography and its complexing rate in the ~erron test.
using such criteria the AlC group of complexes can be broadly characterized by having a diffusion constant in gel permeation chromatography which is within that range generally found for the ~lb group of complexes and a complexing rate in the range of the AlC complexes in the ferron test. Such anomalous results clearly indicate that the complexes within the Al group have a distinct structure not heretofore recognized or appreciated. Hereinafter (and in the claims) the term, "Al ", will refer to that group of complexes in aluminum chlorhydroxide which are more efficacious and exhibit anomalous results in gel permeation chromatography and the ferron reaction.
Generally, the diffusion rates in gel permeation chromatography and the reaction rates in the ferron complexing test will vary with the conditions under which such procedures are conducted. Accordingly, in order to more specifically define the Al group of complexes it is desirable to specify the conditions under which such procedures are conducted.
Generally, the Al group of complexes can be said to have a diffusion constant in gel permeation chromatography between 0.1 and 0.7, preferably between 0.2 to 0.65 and more preferably between 0.3 to 0.55 when such procedures are carried out under the following sets of conditions:

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Concentration of Aluminum Chlorhydra~e - 10~ by w~ight Temperature - Room Temperature Type of gel material. - Em Gel PGM-2000 (trade mark of E, Merck Co. for a polyethylene glycol dimethacrylate type gel).O
In the ferron test the AlC group of complexes requires a minimum of about 3 days for the reaction to go to completion under the follow:ing conditions-Reaction medium ~ Water ConcO of ferron - 2,8 x 10 M
ConcO of Aluminum Chlorhydrate - 2.3 x 10 4 M
Temperature - Room Temperature pH - 5 Buffer - ~ydroxylaminehydrochloride? hydrochloric acid and sodium ac tate, At least in aluminum chlorhydrates which have a pH of about 4.0 to 4O7~ eOg, A12(OH)5Cl~ the Al~ group of complexes can be further characterized by the fact that in gel permeation chromatography (using an Em* Gel) they produce a doublet within the peak in which they fall (e.g, between diffusion constants 0~3 to 0.55)~ In FigO 1 there is shown a chromatogram of an aluminum chlorhydroxide within the scope of the present invention wh~ch was run using an Em* Gel PGM-20000 The two peaks of the doublet have been found to be distinct fractions and the first peak~ presumably comprising the larger molecules of the two S~ - 5 -* trade mark cb/ , ~

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fractions, has been called H and the second L. SUC'h fractions may also be referred to as AlH and AlL .
rrhe AlC group oE complexes of this invention can be still further characterized by the fact that the molecules making up the group are less than lOOA in size in aqueous solutions.
For the purpose of this invention, the percent of the Al group in the aluminum chlorhydroxides is determined by assuming that the Al group of complexes plus the Al group of complexes is about 90% by weight of the aluminum chlorhydroxide and then multiplying 90% by the ratio of the height of the AlC
peak to the combined heights of the Al and Al peaks on a gel chromatogram such as shown in Fig. 1, i.e., %AlC = _ _ Al x 90%
AlC t Al Generally the novel aluminum chlorhydroxide of this invention may be prepared by aging the aluminum chlorhydroxide ; presently available (e.g., those containing less than about 30 of the Al group? in an aqueous medium until such aluminum ; chlorhydroxides contains at least 45% of the Al group as determined by the peak height ratio. In carrying out the aging process it has been generally found that the reaction is temper-ature, concentration and time dependent. Usually the aging should be carried out at temperatures below 100C, preferably at 90C or lower and more preferably at about 80C or lower.
Generally there is no lower limit on the aging temperature but ~ mg /J c - 1 3 ~ 3 ~

when the aging is carried out at room temperature or lower the reaction rate is considerably slower, e.g., a 10% by weight sollltion at room temperature takes about ~ive weeks. It is preferable that the aging be carried out at temperatures above 50C. As to the concentration, it has been generally found that the lower concentration should be at least 5% by weight prefer-ably at least 7.5% and more preferably 10% or above~ As to the upper limit on concentration it is generally below 40% by weight, more particularly below 35% by weight and preferably below 30%.
At between 27.5% and 7.5% and more particularly between 25%
and 10% especially good results were obtained. Within the temperature and.concentration ranges specified above, the reaction rate of the aging process will generally increase as the temperature is raised and decrease when the concentration is increased. The effect of the concentration and temperature on the reaction is illustrated in Table I which is set for-th below:
TA:BLE I
Time Required to Produce Aluminum Chlorhydroxides _(ACH) Which Contain at Least 70% Al TEMPERATURE C

50O 65 ~0 ACH CONCENTRATION
10% 1 week1 day 8 hours 15% --~ days 16 hours 25% ------ 3 weeks 1 week mg/~ - 7 -163~1~

Generally -the condi-tions whlch are most conductive for producing the aluminum chlorhydroxides of this invention will promote the depolymeri~ation of the larger si~e polymeric molecules and the overall compositions of the resulting product in water will generally be substantially free, i.e. contain less than 2% by weight of molecules greater than lOOA in size.
After the aluminum chlorhydroxides of this invention have been produced by the aging processes set forth above the reaction solutions may be concentrated by distillation.
Generally such distillakions are carried out at temperatures below 100C and more preferably below about 80C and at reduced pressures, so as not to convert the aluminum chlorhydroxide to aluminum oxide. Particularly good results were obtained by carrying out the concentration step at 34C to 38C and 28 mmHg pressure~ As the concentration of the aluminum chlorhydroxides of this invention increases by removal of water during the distillation, the concentration of the AlC group is believed to start to gradually decrease as the overall concentration of the aluminum chlorhydroxide begins to exceed about 30~. Thus, although it is possible to produce 50% solutions by distillation such solutions are not stabLe for extended periods and the amount of the Al present will gradually decrease until the amount present is below that specified for the aluminum chlorhydroxide of this invention. In light of such instability at higher concentrations it has been found that if the aluminum , chlorhydroxides are going to be used in water-based antiper-spirant compositions they should be concentrated to a range, mg /Je - 8 -1 ~ fi ~

e.g. between about 10% to about 30~ in which they wlll generally remain stable. If it is desired to produce the aluminum chlorhydroxides as powders, the reaction solutions may be concantrated, e.g. up to about 50% and then they should be converted to the powder shortly thereafter, e.g. within 2 hours under conditions in which the decrease of the AlC
group does not take place to any great extent. One such method is to rapidly convert the concentrated solu-tions to powders, e.g. by spray drying. Such spray drying processes have been successfully carried out a-t an inlet temperature of 150C and an outlet temperature of 75 to 80Canda feed rate of 280ml per minute. Another method is to convert the concentrated solutions to powders under conditions which the decrease of the AlC group will take place very gradually, e.g. freeze drying. Such freeze drying processes have been successfully carried out at -40C and a pressure of 1 mmHg.
In drying the aqueous solutions to powders, care should be taken no to remove all the bound water because as is known such total removal generally irreversibly destroys the antiperspirant activity of the material. Usually the dried powders should preferably contain 3 to 20~ by weight and more preferably 3 to 15% by weight of bound water. In powdered form the aluminum chlorhydroxides of this invention are quite stable.
The aluminum chlorhydroxides of this invention may be used as antiperspirants in the various forms well known to the art, e.g. solutions, creams, lotions, sticks, roll-ons, pads, ` ~ mg/)~ _ g _ 1 1t;3~
aerosols, etc. When they are used in water-based cornpositions or in, e.gO water-alcohol based compositions the amount of water present should preferably be such that the concentration of the aluminum chlorhydroxides in the water, alone, i.e. exclusive of all other liquids present, is in a range between about 5 and 30 by weight in which (range) the AlC group is generally stable.
The especially preferred concentratlon is between 7 5% to 27O5%~
- When the aluminum chlorhydroxides of this invention are to be used as powders in substantially anhydrous systems, usually it will not be necessary to use any special precautions because as pointed out above, they are quite stable in this form.
The aluminum chlorhydroxides of this invention are especially useful in anhydrous suspension~type systems well known to the art such as roll-ons and pump and aerosol sprays in which the powders are suspended in hydrophobic vehicles such as isopropyl myristate~ volatile cyclic sllicones, and mixtures thereof.
Such systems usually also comprise a suspending agent such as hydrophobic bentonites~ e.g~ Bentone* 34 and 38 and silicas~
e.g. Cab-O-Sil* M5. When the suspensions are used in aerosol form they will also include well known propellants such as the hydrocarbons and the halocarbons~
Unlike the presently available aluminum chlorhydroxides the efficacies of the aluminum chlorhydroxides of this invention are concentration dependent~ This can be quite advantageous in that, within limits, one may formulate antiperspirant com~ositions to provide a desired level of efficacy by merely varying the ~; - 10 * trade mark cb/~ ~'r~

~ 3 6 ~ 3 amount of active material present. Generally in aqueous systems the improved efficacies of the aluminum chlorhydroxides of this invention become more apparent and significant when they are used in amoun-ts above at least 15%, e.g. 20~ by weight. Generally in such aqueous systems at concentrations of 20% or more the aluminum chlorhydroxides of this invention were found to be at least about 20% more efficacious than the aluminum chlorhydroxides presently available.
The following non-limiting examples illustrate the preparation and use of the aluminum chlorhydroxides within the scope of this invention.
EXAMPLE I
A 10% aqueous solution of aluminum chlorhydroxide was aged at 50C for five weeks. The resulting aluminum chlorhydroxide composition which contained about 90% of the Al group was freeze dried to a powder in a laboratory freeze drier at about S mmHg. The powder (ACH') along with a control of regular aluminum chlorhydroxide (ACH) was formulated into water-based antiperspirant compositions containing 10, 15 and 20% by weight of -the aluminum chlor-hydroxides. The resulting compositions were tested for sweat reduction using a trade-recognized gravimetric procedure on thermally stimulated human subjects. The results are set forth in Table II below:

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Table II
Relative Percent Sweat Reduction-9o% Confidence Levels After Six Applications*
Concentration Relative Percent Sweat Reduction ACH AC~I
10% 36.7 ~0.5 15~ 37.8 41.8 20% 39.3 4~.1 As can be noted, especially at the 20% level, the aluminum ' chlorhydroxides of this invention are significantly superior to the presently available aluminum chlorhydroxides.

, *A number of applications of the product which the trade would recognize as being reflective of the typical efficacy of the antiperspirant.
EXAMPLE II
300 gallons of a 10% by weight aqueous solution of a commercially available aluminum chlorhydroxide were aged at ~0C for 16 hours. At the end of the aging period, a small aliquot of the composition was subjected to gel permeation chromatography. The chromatogram indicated that the aluminum chlorhydroxide present contained at least 90% of the Al group. About lOKg of the composition was freeze dried at -40C and l mmHg to provide about lKg of powdered material.
A chromatogram of a 10% reconstituted solution Gf the freeze dried material was identical to that of the mother solution thus indicating that the aluminum chlorhydroxide of this invention is stable to freeæe drying.

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EXAMPLE III
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The aluminum chlorhydroxide powders produced in Example II (ACH') were ground and sieved, using a 230 mesh sieve, and were formulated into a suspension-type, substantially anhydrous, roll-on antiperspirant composition~ along with a regular powdered ACH (control)~ The makeup of the formulations were as followso Ingredients Formulations (Percent by weight) ACH' ACH
(Control) ~CH 7 20 0 _ ___ ACH ~ 20.0 Volatile cyclic silicone 74 0 74 0 Bentone 38 (a hydrophobic quanternized bentonite clay) 3 50 . 3~50 Alcohol (200 proof) 2031 2.31 Deionized water 0 19 0.19 100~ 100~
The resulting compositions were tested for sweat reduction using a trade-recognized gravimetric procedure on thermally stimulated human subjectsO Th~ ACH' composition was found to ~e significantly superior to the ACH (control) composition in reduciny sweatO

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XAMPLE IV
A 10% aqueous solution of a commercially available aluminum chlorhydroxide was aged in a manner similar to that in Example II and concentrated to about a 50% solution at a temperature of about 3~C to 38C and a pressure of 28 mmHg.
The concentrated solution was spray dried at an inlet temperature of about 150C, an outlet temperature of about 75 to 80C and a feed rate of about 280 ml per minute.
When the resulting material was tested as an antiperspirant in a suspension-type composition similar to that of Example III, except that 25% of the material was used it gave comparable results.
In the above Examples and the work described herein i the aluminum chlorhydroxide, used, had an empirical formula of about A12(OH)5Cl D
Having thus disclosed the invention, what is claimed i s :

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Claims (11)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for substantially improving the antiperspirant efficacy of aluminum chlorhydroxide, said process comprising aging, at a temperature below 100°C, said aluminum chlorhydroxide in an aqueous medium, at a concentration of from 5 to 40 weight percent, until said aluminum chlorhydroxide comprises at least 45 weight percent of an AlC' group of complexes, said AlC' group of complexes being characterized by having a diffusion constant in gel permeation chromatography within that range generally found for the Alb group of complexes, by exhibiting a complexing rate in the ferron test in the range of the AlC group of complexes, of at least about three days for completion of the reaction, and by at least 98 weight percent of the molecules within said AlC' group °
of complexes being less than 100 A in size in aqueous solutions.

2. The process defined in claim 1, wherein said temperature is from 50°C to 80°C.

3. The process defined in claim 1, wherein said concentration is from 7.5 to 27.5 weight percent.

4. The process defined in claim 1, 2 or 3, wherein said concentration is from 10 to 25 weight percent.

5. The process defined in claim 1, 2 or 3, wherein said aging is carried out until said aluminum chlorhydroxide comprises at least 60 weight percent of said AlC' group of complexes.

6. The process defined in claim 1, 2 or 3, wherein said aging is carried out until said aluminum chlorhydroxide comprises at least 70 weight percent of said AlC' group of complexes.

7. The process defined in claim 1, 2 or 3, wherein the resulting aqueous composition is spray dried to a powder.

8. The process defined in claim 1, 2 or 3, wherein the resulting aqueous composition is freeze dried to a powder.

9. The process defined in claim 1, 2 or 3, wherein said aluminum chlorhydroxide has an empirical formula o approximately Al2(OH)5Cl.

10. The process defined in claim 1 or 2, wherein said concentration is from at least 5 to less than 30 weight percent.

11. The process defined in claim 1 or 3, wherein said temperature is from room temperature to 80°C.