CA1299810C - Synthetic polymer propellant systems - Google Patents

Abstract

Abstract Compositions and a process for manufacture are provided for synthetic polymer-propellant systems that form cohesive foamed structures from which aqueous solutions can be expressed, where the useful temperature range over which these structures form is broadened by using a propellant mixture consisting predominantly of a propellant that is a poor solvent for the polymer and has a vapor pressure in the range of 10-35 psig at 20C in combination with a small amount of a propellant that is a good solvent for the polymer; and where these coherent foamed structures can be formed even with aqueous solutions containing 0 to about 30% alcohol, provided that insoluble fine-particle solids that do not pack and become difficult to redisperse are included in the composition.

Description

' ~998~0 4' 7 Backqround Of Invention 8 ,This invention is concerned with polymer-propellant 9 compositions that are capable of forming foamed structures 10 l containing open and/or closed cells from which an aqueous ~ solution can be expressed. Similar compositions have been 12 l described by Spitzer et al U.S. Pat. Nos. 3,912,665,-6,-7, 13 patented October 14, 1975. These earlier compositions suffered 14 from a number of disadvantages includng the difficulty of 15~ preparation and the narrow temperature range over which 16 coherent foamed structures could be obtained.
17 A practical procedure for preparing polymer-propellant 18 compositions that are capable of forming foamed structures 19 containing open ~d~or closed cells is described by Osipow, et " ~
J-S 20 al in U.S. Patent 4,328,319. This process comprised coating 21 the synthetic polymer in particulate form with an inert solid 22 material insoluble in the propellant.
23 Spitzer, et al in U.S. Patent 4,422,877 described 24 synthetic polymer-liquified propellant compositions capable of 2S forming a cold foamed structure having a temperature at least 26 30C below the ambient temperature at which the cold foamed 27 structure is formed, which contain from 50 to 90% be weight of LOp~lld~l~ naVlll~ d ll~d~ OL Vd~llJLl:~dtlCJ~ L d~ L~d~ 55 29 calories per gram, and at least one liquified propellant 30 ; boiling below -lOC.

~;~99810 S~mmary of the Invention According to an aspect of the invention there is provided polymer-propellant compositions that for~ coherent fôamed structures frorn which aqueous solutions can be expressed consisting of about 5 to about 40% by weight of polymer, from about 25 to about 60% by weight of propellant based on the weight of the composition, where the useful temperature range over which such coherent foam structures can form are extended at least to the range of 15C to 32C, by employing a propellant mixture that contains from about 50 to 98~ by weight of one or ln more propellants selected from the group consisting of n-butane, isobutane and 1,2 dichlorotetrafluoroethane, and from about 2 to about 25% by weight of one or more propellants selected from the group consisting of dimethyl ether and l-chloro~ dufluoroethane.

L ,~, ;~-003 , i , ~299810 1 i ' ;~
3 ~Nature of the Invention 4 j!It has now been found that the objects of the instant 5 ¦¦ invention can be realized usinq polyisobutyl methacrylate as 6¦~ the polymer of the polymer - propellant composition. The 7 ll molecular weight of the polymer is not critical and it can 8!l range from 25,000 to about 500,000. The composition should 9!, contain from about 5 to about 40% by weight of polymer. The 10ll lower concentration levels are employed with higher molecular ~ weight polymers and the higher concentration levels with 12~l polymers of lower molecular weight. If the concentration is 13ll too low the foamed struct~re will be excessively weak, while if 14 l¦ it is too high, the polymer solution will be too viscous to mix 15 ll readily with the aqueous phase.
16,, It is necessary to plasticize the polymer, both to 17,l obtain a coherent foamed structure and to obtain a pad 18¦` structure that is soft and fle~ible, rather than harsh and 19l brittle. However, it is important not to over-plasticize, 20l~ otherwise the structure will be weak and it will stretch 21l, e~cessively during use. If still more over-plasticized, it 22 1l wili be a sticky paste rather than a foamed structure.
23 Any of the wide variety of plasticizers may be used, 24l! as shown in the prior art. It is preferable, however, to use a 25~ plasticizer that only exerts a mild placticizing effect, so 26 that small variations in dosing will not substantially change 27i! the character of the product. Vegetable oils meet this 28 , requirement. The propellants also act as fugitive 2g plasticizers, since they do not evaporate completely within the seconds that elapse between the time that the foamed structure 565-003 12998~0 "

1 is formed and it is used.
The choice of propellant plays an important role in 3 extending the temperature range over which cohesive foamed 4l structures can be obtained. In accordance with the instant 5l invention, the propellant should be a mixture of propellants 6 ! consisting predominantly o propellants that are poor solvents 7'1 for the polymer and have relatively low vapor pressures, i.e.
8 1l about 10 to 35 psig at 20C. These propellants should comprise 9 l from about 50 to about 98~ of the propellant mixture by weight 10, and should be selected from the group consisting of n-butane, 11 ! isobutane, and 1, 2-dichlorotetrafluoroethane. The use of 12~' these propellants to a predominant extent, and in particular 13~l n-butane and 1, 2-dichlorotetrafluoroethane, extends the upper 14 " temperature range at which coherent foamed structures are obtained.
16 It has now been found that the second component of the 17 propellant mixture should be a propellant that is a good 18 sclvent for the polymer and should be selected from the group 19 consisting of dimethyl ether and l-chloro-l,l difluoroethane.
These propellants should comprise from about 2 to about 25% by 21' weight of the propellant mixture. Combinations of these good 22 solvent propellants as well as com~inations of the relatively 23~ low vapor pressure propellants may be used.
24 In the absence of these good solvent propellants, at cold ambient temperatures the polymer-propellant solution ~orms 26 a coacervate consisting of a polymer-rich phase and a polymer-27 poor phase. The polymer-rich phase tends to be too viscous and 28 a coherent foamea structure does not torm. rne good solvent 29 tends to prevent the formation of a coacervate and thus it extends the lower temperature range at which coherent foamed 17~99810 565-0')3 1; ~
"

1 structures form.
In addition to these essential propellants, other 3l' liquified propellants may be used. These include n-propane, 4 11' dichlorodifluoromethane, and 1, 1 difluoroethane. The 5¦j propellant mixture comprises from 20 to 60% by weight of the 6l, composition.
7' The second liquid phase of the composition is an 8,l aqueous phase-containing emulsifying agents and active . 9 1 ingredients which may include deodorants, antiperspirants, 10l, bactericides, fungicides, antibiotics, moisturizers, keratolytic agents, etc. Until now, it has been necessary to 12 use an aqueous solution containing at least about 30% of an ., i 13 alcohol, such as ethanol or isopropanol, in order to obtain a 14 I coherent foamed structure from which the aqueous solution could 15~~ be expressed. In some instances, it has been possible to 16l replace part of the alcohol by a glycol-ether, such as 17' dipropylene glycol methyl ether. In the absence of this large 18 amount of alcohol, an aqueous foam formed. It appears likely 19`~ that the alcohol serves as an anti-foam, to repress the foaming 20 l of the aqueous phase and enables a coherent foamed structure to 21;l form.
22 It has now been discovered that various fine-particle 23 solids that are not soluble in the composition can be used 24 ' instead of all or part of the alcohol to enable coherent 25 ; structures to form. Thus, the aqueous solution may contain 26 from 0 to about 30% by weight of water-soluble alcohol, 27 provided these fine-particle materials are present. With 28 higher concentrations of alcohol, i.e., 30 to 60% of the 29 aqueous solution by weight, these fine-particle solids are not essential. It is also necessary that the powder not pack lZ99810 . ,1 1 during storage and become difficult to redisperse. The materials that have been found to be suitable are selected from 3 , the group comprising colloidal silica, bentonites, aluminum 4,' pigment and the soaps of fatty acids containing about 9 to 22 5 1¦ carbon atoms and di- and poly-valent cations, in particular, 6li the stearates and palmitates of aluminum, calcium, magnesium 7 and zinc.
81, Generally, from about 0.03 to about 3%, and preferably 91l from about 0.1 to about 1%, of fine-particle solids are used, 10 1 based on the weight of the composition. If the concentration ~ is too low, it is ineffective, while higher concentrations 12 , reduce the cohesiveness of the foamed structure.
13 Employing the propellants and fine particle solids of 14 the instant invention, as required, a surprisingly convenient 15 ll process for the manufacture of these pressurized compositions 16 has been discovered. A concentrate is prepared that is a 17 dispersion of polyisobutyl methacrylate in water. The 18 dlspersion may include all of the ingredients except the 19 propellant mixture and those ingredients that will adversely 20" affect the stability of the dispersion. The latter are 21 I combined into a second concentrate. The dispersion may be a 22 , polyisobutyl methacrylate latex to which compatible ingredients 23 ~ have been added.
24~ The concentrates are dosed into aerosol containers in the conventional manner. The propellant mixture is added, 26 either through the valve or under the valve mounting cup, as is 27 customary. It is then necessary to shake the containers for a 28 few seconds, i.e., S to ~U secon~s. lne contalners may ~e 29 shaken while on the line, either before or after passing through the water-bath test, or they may be packed into cases ~1 !

12998~ l 1l, and then shaken. The shaking action brings the dispersed polyisobutyl methacrylate particles into contact with the 3 propellant mixture and they dissolve almost instantaneously, 4l~ completinq the manufacturing process.
5 ii The compositions of the instant invention consist 6l essentially of the follcwing, in parts by weight of the total 7 ' composition:

Polyisobutyl methacrylate 5 - 40%
Aqueous solution 25 - 60%
'' Propellant 20 - 60%

12 provided that from about 50 to 9~ of the propellant mixture by 13 weight consists of propellants that are poor solvents for the 14l~ polymer and have vapor pressures in the range of lO to 35 psig 15l at 20C. Such proprellants are selected from the group 16 ` consisting of n-butane, isobutane and l, 2- dichlorotetra-17l fluoroethane, and from about 2 to about 25% of the propellant 18 mixture by weight is selected from the group consisting of 19 ' dimethyl ether and l-chloro-l, l difluoroethane, for the purpose of extending the temperature range over which coherent 21 ' foamed structures are obtained; and where the aqueous solution 22 contains less than about 30% alcohol, the composition also 23 contains from about 0.03 to about 3.0% by weight of insoluble 24 fine-particle solids selected from the group consisting of colloidal silica, bentonite, aluminum pigment and the soaps of 26 fatty acids containing 9-22 carbon atoms and di- and polyvalent 27 cations, for the purpose of insuring that a coherent foamed 28 structure will form.

29 In place of polyisobutyl methacrylate other various acrylic and methacrylic copolymers having similar 565-003 1~99810 ~, , 1ll characteristics, including solubility in the propellant may be ~ l used in the instant invention. Examples of such copolymers are 3 I normal butyl methacrylate, copolymers of ethyl methacrylate and 4 , dodecyl methacrylate, etc.
5 l¦ The coherent foamed structures that are produced in 6 ll accordance with the instant invention may be used as cleansing 7~~ pads for cleaning parts of the body or for cleaning various 8~, surfaces. Alternatively, they may be used as applicator pads 9~, that deliver aqueous solutions as well as oils along with the lOIl aqueous solution. Thus, they may be used to apply medicinal ~ agents, lubricants, furniture polishes, etc.
12 l¦ The foamed structured pads of the present invention 13l' may be used for the same purpose of those of U.S. Patent 141l 4,32~,~19. See, for example, column ll, line 38 through column 15l, 15, line 40 of the aforementioned patent.
16 Example l 17 ll ~his example illustrates an astringent facial 18~ cleansing pad that exudes an aqueous solution containing 50%
19 alcohol by weight. The composition forms coherent foamed 20 ~I structures over the temperature range 15C to 32C.
2111, 22 I Parts 8v Weight 23 I Part l 24 Sodium lauryl sarcosinate 0.1 Magnesium stearate 0.3 25 Ethanol 25.7 Water 25.7 26 Polyisobutyl methacrylate 17.4 27 Part 2 28 Polyoxypropylene(lO)cetyl ether 0.5 Corn oil 0.9 29 Mineral oil 1.5 565-003 ` 1~998~0 1 l Part 3 Isobutane 15.7 ' n-Butane 10.0 3 ll 1, Chloro-l, 1 difluoroethane 1.2 4,~ 1 5 ll The components of Part 1 are combined to form a slurry 6 l of the polymer and the magnesium stearate in the hydro-alcohol 7 solution. The components of Part 2 are combined to form an oil 8l solution, and the components of Part 3 are combined to form a 9~1 propellant mixture. Part 1 and Part 2 are separately dosed 10" into aerosol cans, the valves are crimped on, and the propellant mixture is added through the valve. The cans are 12,¦ then shaken on the line for 10 seconds to dissolve the polymer.

14 '~ EsamPle 2 15 l This example illustrates a lathering scrub pad. It is 16'l used with water like a wash cloth impregnated with soap. The 17 ' scrub pad lathers and cleans well. The hydro-alcohol solution 18 used in the composition contains 33% alcohol. The composition 19 forms coherent foamed structures over the temperature range 15C
20, to 32C.

22 Parts ay Weiqht 23 Part 1 24 Sodium lauryl sarcosinate 3.3 Magnesium stearate 0.3 251 Witch Hazel 13.3 Ethanol 16.8 26 Water 21.6 Polyisobutyl methacrylate 15.0 Part 2 Polyo~ypropylene(lO)cetyl ether 0.5 29 Corn oil 1.0 Mineral oil 1.6 30 ;

g 5-00_ ~

1 l Part 3 1299810 Isobutane 15.8 I n-Butane 8.6 3l 1, Chloro-l, 1 difluoroethane 1.7 4 i 5 I The procedure is the same as for Example 1, except 6 I that after adding the propellant, the cans are tested for 7 ¦ leakage by passing through a water bath at 130F. They are then !; packed into cases and the cases are shaken for 30 seconds to Ij dissolve the polymer.
9 jl lo !i jj ExamPle 3 IThis example illustrates a facial cleanser-freshener ~I pad that cools as well as cleanses the face. The hydro-alcohol 13 l li solution used in the composition contains 34% alcohol. The 14!!
I composition forms coherent foamed structures over the ' temperature range l5C to ~2C.

i¦ Parts BY Weiqht 18 1l, Part 1 ~, Pluronic L 121* (trade mark) O . 2 201~' Zinc stearate 0.3 ¦i Witch Hazel 10.0 21 1! Ethanol 11.6 ,I Water 15.0 22 Polyisobutyl methacrylate 14.7 23 ! Part 2 24 l Corn oil 1.3 ~, Mineral oil 1.4 25, Part 3 26 ~
!l 1, 2 Dichlorotetrafluoroethane 38.6 27 1, Chloro-l, 1 difluoroethane 6.9 ;

~Block copolymer of propylene oxide and ethylene oxide 29 ' ; The procedure is the same as for Example 1.
30,i . . .

-003 12998~0 ., . i 1, ExamPle 4 ~ll This example illustrates a vaginal and anal 3 ll deodorant-cleansing wipe. The composition does not contain any 4 ll alcohol to avoid any tendency for smarting. The composition 5 !~ forms coherent foamed structures over the temperature range 15C
6il to 32C.
Il 8j¦ Parts BY Weiqht 9 I Part 1 10 ¦ Chlorohexidene gluconate 0.9 ¦ Pluronic L 72 ~ (trade mark)O . 2 11 Colloidal silica 0.4 Water 38.3 12 ¦ Polyisobutyl methacrylate 19.3 13 ¦I Part 2 14¦l Corn oil 2.5 ¦I Mineral oil 2.5 ! Part 3 6' ¦~, n, 8utane 32.2 17,l Dimethyl ether 4.2 *~lock copolymer of propylene oxide and ethylene oxide ', The procedure is the same as for Example 2.
20j 21 ¦ ExamPle 5 22 This example illustrates the use of a latex to form a composition suitable for use in the relief of acne. The pads have good cleansing action and leave a deposit that is keratolytic and antiseptic. The composition forms coherent j foamed structures over the temperature range 15C to 32C.

- Par~s ~y Wei~ht 28 i Part 1 Polyisobutyl methacrylate latex (42%) solids 49.1 30 Colloidal silica 0.4 i65-003 11 !i Part 2 ~ I Cetyl trimethyl ammonium bromide 0 1 3 ! Salicylic acid o g Polyoxypropylene (10) cetyl ether 1.9 Tributyl citrate 1 9 4 Ethanol 19 5 5 Part 3 I
6l Isobutane 12 4 ¦ n-Butane 11 5 7 1¦ l-Chloro-l,l-difluoroethane 2.3 Il Separately, the ingredients of Part 1 and Part 2 are jj combined. Each of the two parts are dosed into aerosol cans, ¦I the valves are clinched on and the propellant mixture, Part 3, ¦¦ is added through the valve. The cans are then shaken on the ¦~ line to dissolve the polymer.
14 11 .
15¦~ ExamPle 6 16 !j This example illustrates a composition suitable for the treatment of cuts, scrapes, burns, etc. It is sufficiently ¦ cooling to provide relief from pain. It contains a stiptic to stop bleeding and an antiseptic. The level of alcohol is only ,1 15% on the hydro-alcohol solution, so that it does not cause an ¦! alcohol st~ng. The composition forms coherent foamed i structures over the temperature range 15C to 32C.
22,' 23l' j Parts BY Weiqht 24 , Pa t 1 Il Pluronic L121~ (trade mark) O . 2 26 Magnesium stearate 0.4 ,; Cetyl trimethylammonium bromide 0.1 27 ! Aluminum chlorohydrate 0.5 .i E1-hannl 28li Water 36 3 Polyisobutyl methacrylate 21 8 29 l 0,l Part 2 Corn oil 2.5 I l ~Z99810 1,l Mineral oil 2.0 2,l Part 3 3l n-Butane 26 0 4l Dimethyl ether 3 6 5 l¦ *Block copolymer of propylene oxide and ethylene oxide 6!1 The procedure is the same as for Example 1.

9 1 li 12,' 21 .

23 ' .j !

26j~
27 .
2~

Claims (9)

1. Polymer-propellant compositions that form coherent foamed structures from which aqueous solutions can be expressed consisting of about 5 to about 40% by weight of polymer, from about 25 to about 60% by weight of propellant based on the weight of the composition, where the useful temperature range over which such coherent foam structures can form are extended at least to the range of 15C to 32C, by employing a propellant mixture that contains from about 50 to 98% by weight of one or more propellants selected from the group consisting of n-butane, isobutane and 1,2 dichlorotetrafluoroethane, and from about 2 to about 25% by weight of one or more propellants selected from the group consisting of dimethyl ether and 1-chloro-1,1-dufluoroethane.

2. As in Claim 1, where the polymer is polyisobutyl methacrylate and the propellant mixture contains n-butane and dimethyl ether.

3. As in Claim 1, where the polymer is polyisobutyl methacrylate and the propellant mixture contains n-butane and 1-chloro-1,1-difluoromethane.

4. As in Claim 1, where the polymer is polyisobutyl methacrylate and the propellant mixture contains 1,2-dichlorotetrafluoroethane and dimethyl ether.

5. As in Claim 1, where the polymer is poiyisobutyl methacrylate and the propellant mixture contains 1,2-dichlorotetrafluoroethane and 1-chloro-1,1-difluoroethane.

6. As in Claim 1, where the aqueous solution contains from 0 to about 30% alcohol by weight and an insoluble, fine-particle solid that does not pack is included in the composition to enable a coherent foamed structure to form.

7. As in Claim 6, where from about 0.03 to about 3% by weight of an insoluble fine-particle solid that does not pack is employed, based on the weight of the composition, selected from the group consisting of colloidal silica, bentonites, aluminum pigment, and soaps of 9-22 carbon atom fatty acids and di-and poly-valent cations.

8. A process for the manufacture of the composition of Claim 1, where the polymer is dispersed in the aqueous solution before dosing into the individual containers, the propellant misture is added last, and the composition is then shaken.

9. As in Claim 8, where the polymer dispersion is a latex.