APPARATUS FOR MAKING A POST-FOAMING GEL

Abstract: An apparatus (10) for making a post-foaming gel comprising, a first cylinder (12) having a chamber (14) and a slidable piston (16) separating the chamber (14) into a first compartment (18) to receive a gel base and a second compartment (20), a second cylinder (22) having a chamber (24) and a slidable piston (26) separating the chamber (24) into a first compartment (28) to receive the gel base and a second compartment (30), a conduit (38, 40) connecting the first compartments (18, 28) of the first and second cylinders (12, 22), a device (72) for reciprocating the pistons in the first and second cylinders (12, 22) to cycle the gel base through the conduit (38, 40) between the first compartments (18, 28) of the first and second cylinders (12, 22), and a device (42) for introducing a foaming agent to the gel base while it is being cycled between the cylinders (12, 22).

Description: BACKGROUND OF THE INVENTION The present invention relates to an apparatus for making a post-foaming gel. Before the present invention, attempts have been made to add foaming agents, such as pentane/butane mixtures to gel bases in conventional partly filled pressure vessels to make a post-foaming gel. However, any post foaming gel of cosmetically acceptable stiffness will tend to foam spontaneously when exposed to atmospheric pressure if it contains bubbles of air or hydrocarbon. These act as nuclei for foaming, by expanding and shearing the gel in their immediate vicinity. This means that pentane/butane mixtures cannot be incorporated into gel base in a conventional, partly-filled pressure vessel, even when the headspace is pressurized with air or nitrogen. Inevitably some of the water-soluble gas will be entrained in the gel. The resulting spontaneous foaming makes filling into cans very difficult and messy. Even then the product will not settle down on storage to give a satisfactory result. Taking a potentially 'easy' situation, such as adding only isopentane (B.Pt. 29 o C) or n-pentane (B.Pt. 37 o C), there are still problems. Assuming a good gel is produced by cold mixing, you will find that at temperatures around 20 o C the mixing does vaporise significant amounts of foaming agent and the resulting gel is foamy. These bubbly gels are not suitable for packing into cans because the external propellant used with the cans gives insufficient pressure to collapse the bubbles on storage. This is largely due to the fact that these gels have a yield value such that they resist the applied pressure (or fail to transmit the full effect to the bubbles). A post-foaming gel is disclosed in U.S. patent 3,541,581. A continuous method and apparatus to make a post-foaming gel is disclosed in U.S. 4,405,489. The filling of an aerosol can containing an interior plastic bag which holds the product to be dispensed is disclosed in U.S. 4,589,452. US-A-4 350 650 discloses a method for admixing liquids. An apparatus carrying out the method comprises a cylindrical chamber, two counteracting pistons driven to slide within the chamber and a partition block which splits the chamber into two compartments communicating through a conduit in the block. Two batches of liquid fed respectively to the two compartments are repeatedly cycled between the compartments and passed through the throttling conduit whereby shear stresses in the laminar flow motion result in an intimate admixture of both liquid components. There is no possibility to control the temperature during mixing. Applicants parallel application EP-A-0 324 931 of the same effective date relates to an apparatus of the same kind as the present invention. It is directed to an arrangement connecting the two pistons equalizing the movement of both by means of a shaft arrangement including a slidable and flexible coupling to allow for volume changes in the compartments due to added foaming agent. Summary of the Invention According to the present invention an apparatus for making a post-foaming gel is provided, comprising: a first cylinder having a chamber and a slidable piston separating the chamber into a first compartment to receive the gel base and a second compartment to receive a compressed gas; a second cylinder having a chamber and a slidable piston separating the chamber into a first compartment to receive the gel base and a second compartment to receive a compressed gas; conduits connecting the first compartments of the first and second cylinders to a heat exchanger; means for reciprocating the pistons in the first and second cylinders to cycle the gel base through the conduits among the first compartment of the first cylinder, the heat exchanger and the first compartment of the second cylinder, said reciprocating means comprises a control system for sequentially introducing a compressed gas into the second compartments of the first and second cylinders; and an inlet conduit provided with a valve for introducing a foaming agent to the gel base while it is being cycled among the heat exchanger and the first compartments of the cylinders is connected to one of said conduits communicating with said first compartment of said second cylinder. DESCRIPTION OF THE DRAWINGS In the drawings: Fig. 1 is a diagrammatic view of an apparatus for making a post-foaming gel of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to Fig. 1, there is shown an apparatus generally designated 10 for making a post-foaming gel from a gel base and foaming agent. The apparatus 10 has a first vertically disposed cylinder 12 having a chamber 14 and a slidable piston 16 separating the chamber 14 into a first upper compartment 18 to receive a gel base and a second compartment 20 to receive a compressed gas. The apparatus 10 has a second vertically disposed cylinder 22 having a chamber 24 and a slidable piston 26 separating the chamber 24 into a first upper compartment 28 to receive the gel base and a second compartment 30 to receive a compressed gas, with the first and second cylinders 12 and 22 being disposed in a side-by-side configuration. The apparatus 10 has a heat exchanger 36, and a first conduit 38 connecting the heat exhanger 36 to the first compartment 28 of the second cylinder 22, and a second conduit 40 connecting the heat exchanger 36 to the first compartment 18 of the first cylinder 12. The first conduit 38 has a first valve 42 for introducing a foaming agent into the first conduit 38. The first and second conduits 38 and 40 have respective valves 44 and 46 for a purpose which will be described below. The first and second conduits have respective bleed lines 48 and 50 which will be further described below. The first conduit 38 has a pressure gauge 52, and the second conduit 40 has a pressure gauge 54 and a pressure switch 56 to relieve pressure in the event that there exists excessive pressure in the apparatus 10. The gel base is supplied by a pump 58 through a valve 60 into the second conduit 40 and apparatus 10 as will be further described below. The second conduit 40 also has a thermocouple 62 to measure the temperature of the gel base in the apparatus 10. The piston 16 of the first cylinder 12 has an elongated shaft 64 extending vertically out of the cylinder to activate a respective switch 66 when the piston is located in an upper part of the first cylinder 12. The piston 26 of the second cylinder 22 also has an elongated shaft 68 which activates a respective switch 70 when the piston 26 is located adjacent an upper part of the second cylinder 22. The switches 66 and 70 are pneumatically connected to a control system 72 of known type, in order to render the apparatus fully flame proof, which controls the passage of pressurized gas to and from a source line 74 of gas through conduits 76 and 78 to the second compartments 20 and 30 of the respective first and second cylinders 12 and 22. The gel base is made in the following manner according to the formulation set forth below: (1) Add approximately 20% of the water to a closed mixing vessel. (2) Add fatty acid to the mixing vessel and then the GMS/color then heat to 80-85°C until all powdered materials have melted. (3) Add the triethanolamine to the vessel with agitation to form a soap. Cool to 60°C. Add the Hydroxyethyl cellulose. (4) Cool to 40°C and add the Hydroxypropyl cellulose. (5) Add the sorbitol solution, with agitation, to the aqueous soap. (6) Cool the mixture to 30°C, add the perfume with agitation. The gel base has the following formulation: BASE % Palmitic Acid 8.0 - 10.0 Stearic Acid 1.0 - 3.0 Triethanolamine 5.5 - 7.5 Sorbitol - 70% solution up to 3.0 Hydroxyethyl cellulose 0.1 - 0.4 Hydroxypropyl cellulose 0.05 - 0.15 Glyceryl Monostearate 0.4 - 0.6 Perfume q.s. Coloring Material q.s. Water to 100% The finished product has the following formulation: FINISHED PRODUCT Base as above 97.0 - 98.0 Iso-Pentane 1.5 - 1.8 Iso-Butane 0.5 - 1.2 In use of the apparatus 10, first the control system 72 controls the gas pressure in the second compartments 20 and 30 to position the pistons 16 and 26 adjacent an upper part of the respective cylinders 12 and 22 in order to minimize the amount of air in the cylinders, after which the gel base is passed through the valve 60 into the apparatus 10 while bleeding air through the bleed lines 48 and 50. In this manner, the location of the pistons are controlled while filling the gel base and bleeding air in order to obtain a more controlled filling rate and discharge any residual air from the first compartments 18 and 28 and apparatus 10. Next, the gas is removed from the second compartment 30 of the second cylinder 22 by the system 72 in order to position the piston 26 adjacent the lower part of the second cylinder 22, or vice-versa, the system 72 may lower the piston 16 to a lower position while the piston 26 remains in an upper position, while the gel base is filled into the first compartment of the respective cylinder. Once the pistons 16 and 26 are located in the desired starting positions, the system 72 sequentially introduces and removes compressed gas to and from the second compartments 20 and 30 of the first and second cylinders 12 and 22 in order to reciprocate the pistons in the cylinders and cycle the gel base through the first and second conduits 38 and 40 and heat exchanger 36 while introducing the foaming agent through the valve 42 into the first conduit 38 and apparatus 10, while the system 72 compensates for the added volume of the foaming agent comprising iso-pentane and iso-butane. During foaming agent addition, the cylinders are cycled to avoid accumulation of undispersed material, and final total cycling is dependent on conditions such as formula and temperature. After cycling has been completed, aerosol cans having two compartments are filled from either valve 46 or valve 44, and adjusting air pressure to give controlled delivery of gassed gel. The aerosol valves are crimped in place and the outer compartments of the cans are gassed with a few grams of propellant after which the samples are ready for use. In this manner, a post foaming gel is formed in a simplified manner by the apparatus. According to a method of making a post-foaming gel, a gel is cycled between first and second cylinders, and a foaming agent is introduced to the cycled gel base.

Claims: An apparatus for making a post-foaming gel, comprising: a first cylinder (12) having a chamber (14) and a slidable piston (16) separating the chamber into a first compartment (18) to receive the gel base and a second compartment (20) to receive a compressed gas; a second cylinder (22) having a chamber (24) and a slidable piston (26) separating the chamber into a first compartment (28) to receive the gel base and a second compartment (30) to receive a compressed gas; conduits (38, 40) connecting the first compartments (18, 28) of the first and second cylinders (12, 22) to a heat exchanger(10); means (72, 76, 78) for reciprocating the pistons (16, 26) in the first and second cylinders (12, 22) to cycle the gel base through the conduits (38, 40) among the first compartment of the first cylinder, the heat exchanger and the first compartment of the second cylinder, said reciprocating means comprises a control system (72) for sequentially introducing a compressed gas into the second compartments (20, 30) of the first and second cylinders; and an inlet conduit provided with a valve (42) for introducing a foaming agent to the gel base while it is being cycled among the heat exchanger and the first compartments of the cylinders is connected to one of said conduits (38) communicating with said first compartment (28) of said second cylinder (22). The apparatus according to claim 1, including switches (66, 70) responsive to the location of the pistons (16, 26) and being operatively connected to said control system (72). The apparatus according to claim 2, wherein the pistons (16, 26) include shafts (64, 68) extending out of the respective cylinders, said switches (66, 70) being activated by the shafts. The apparatus according to claim 1, including valves (44, 46) for removing the resulting gel from the apparatus. The apparatus according to claim 1, including means (56) for relieving pressure responsive to excessive pressure in the apparatus. The apparatus according to claim 1, including lines (48, 50) for bleeding air from the apparatus. The apparatus according to claim 1, wherein said control system (72) is adapted to position the pistons (16, 26) with a minimum space in the first compartments (18, 28), before pumping means (58) fill the apparatus with the gel base while bleeding air from the apparatus. The apparatus according to claim 1, wherein said control system (72) is adapted to control gas pressure in the second compartments (20, 30) of the cylinders while introducing the gel base into the apparatus. The apparatus according to claim 1, wherein the first and second cylinders (12, 22) are disposed in a side-by-side configuration. The apparatus according to claim 1, wherein the cylinders (12, 22) are disposed in a vertical configuration. The apparatus according to claim 10, wherein the first compartments (18, 28) of the first and second cylinders are located in an upper part of the cylinder.

Inventors: ELLIS, ROGER DAVID, WIGGLESWORTH, PAUL
Applicants: COLGATE-PALMOLIVE COMPANY
Application year: 1988
Main classification: B01F3
IPC codes: B01F5