APPARATUS AND METHOD 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), and 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), with the first compartments (18, 28) of the first and second cylinder (12, 22) facing each other. The apparatus (10) has a shaft (34) connecting the pistons (16) of the first and second cylinders (12, 22), and a conduit (38, 40) connecting the first compartments (18, 28) of the first and second cylinders (12, 22). The apparatus (10) has a device (52) for reciprocating the pistons (16, 26) in the first and second cylinders (12, 22) to cycle the base through the conduit (38, 40) between the first compartments (18, 28) of the first and second cylinders (12, 22), and 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 and method for making a post-foaming gel. Before the present invention, attempts have been made to add foaming agents, commonly low pressure propellant mixtures, 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 pressurised with air or nitrogen. Inevitably some of the water-insoluble 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°C) or n-pentane (B Pt. 37°C), there are still problems. Assuming a good gel is produced by cold mixing, you will find that at temperatures around 20°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 -A-3,541,581. A continuous method and apparatus to make a post-forming gel is disclosed in U S -A-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 -A-4,589,452. Applicants parallel application EP-A-0 324 934 of the same effective date relates to an apparatus of the same kind as the present invention. It discloses means to simultaneously cycle the gel base, to add and admix the foaming agent and to operate a heat exchanger while the gel base is being cycled between the compartments. US-A-4 350 650 discloses a method for admixing liquids. An apparatus for 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 suggestion to couple both pistons instead of operating them independently. Reference FR-A-2 402 582 describes an apparatus adapted to simultaneously pump two components to be mixed in a predetermined proportion. Two cylinders provided with pistons act as pumps, their pistons being connected by a shaft. In this arrangement the single shaft drives two otherwise independent pumps. In accordance with the present invention an apparatus for making a post-foaming gel is provided, comprising: a first cylinder having a chamber and a slideable piston separating the chamber into a first compartment to receive a gel base and a second compartment to receive a compressed gas; a second cylinder having a chamber and a slideable piston separating a chamber into a first compartment to receive the gel base and a second compartment to receive a compressed gas, with the first compartment of the first and second cylinders facing each other; conduits connecting the first compartments of the first and second cylinders to a heat exchanger; a pneumatic control system for reciprocating the piston in the first and second cylinders to cycle the gel base through said conduits among the first compartment of the first cylinder, the heat exchanger and the first compartment of the second cylinder; 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; characterized by a shaft connecting the pistons of the first and second cylinders; said shaft comprising a pair of segments and including a slideable coupling for slideably connecting the shaft segments to each other. The present invention also provides a method of making a post foaming gel, comprising the steps of: cycling a gel base among a first compartment of a first cylinder, a heat exchanger and a first compartment of a second cylinder; and introducing a foaming agent to the gel base while it is being cycled among the heat exchanger and the first compartments of the cylinders. A feature of the present invention is that the apparatus forms a post-foaming gel from the gel base and foaming agent in a simplified manner. Another feature of the present invention is the provision of a coupling on the shaft for adjustment to allow for volume of the added foaming agent. A further feature of the present invention is that the apparatus eliminates the necessity for a motor drive pump. Yet another feature of the invention is that the apparatus is flame proof. Still another feature of the invention is that the cycle time for forming the post-foaming gel is reduced. A feature of the present invention is that the apparatus is of simplified construction and can be made at a reduced cost. Further features will become more fully apparent in the following description of the embodiments of this invention and from the appended claims. 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; and Fig. 2 is an elevational view, taken partly in section, of a coupling for the apparatus of Fig. 1 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 cylinder 12 having a chamber 14 and a slideable piston 16 separating the chamber 14 into a first compartment 18 to receive a gel base and a second compartment 20 to receive a compressed gas. The apparatus 10 has a second cylinder 22 having a chamber 24 and a slideable 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. As shown, the first and second cylinders 12 and 22 may be connected together by a pair of rods 32, with the first compartment 18 and 28 of the first and second cylinders 12 and 22 facing each other. The apparatus 10 has a shaft 34 connecting the pistons 16 and 26 of the first and second cylinders 12 and 22, respectively, such that movement of the pistons are imparted to each other by the shaft 34. The apparatus has a heat exchanger 36, and a first conduit 38 connecting the heat exchanger 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. Also, the second conduit 40 has a valve 48 for connecting the system to a vacuum in order to eliminate air from the apparatus. The shaft 34 has a coupling 50 for a purpose which will be described below. The apparatus 10 also has a device 52 for sequentially introducing and removing gas into and from the second compartments 20 and 30 of the first and second cylinders 12 and 22 in order to reciprocate the pistons 16 and 26 in the first and second cylinders 12 and 22 to cycle the gel base through the first and second conduits 38 and 40 and heat exchanger 36 between the first and second cylinders 12 and 22. The device 52 comprises a pneumatic control system which cycles the pistons based on air pressure signals from switches operated by the piston shaft. As shown in Fig. 1, the device 52 has a pair of switches 70 and 72 which are sequentially actuated by the coupling 50 as the coupling approaches the respective opposed cylinders 12 and 22. The switches 70 and 72 are connected to a control system 74 of known type which sequentially removes and introduces air under pressure from and to the second compartments 20 and 30 of the respective cylinders 12 and 22 through conduits 76 and 78 which are connected between the second compartments 20 and 30 and the control system 74. The control system 74 is connected to a pair of inlet conduits 80 and 82 to supply compressed air to the control system 74, and the control system 74 is selectively connected to an exhaust. As shown in Fig. 2, the coupling 50 comprises a hollow sleeve 60 secured to shaft segment 34a. An outer enlarged end 62 of shaft segment 34b is slidably received in the sleeve 60 through an opening 64 of the sleeve 60, and the shaft end 62 is biased away from an annular flange 66 of the sleeve 60 by a helical spring 68 extending between the flange 66 and shaft end 62. 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 powders are molten. (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: The finished product has the following formulation: As shown in Fig. 1, the first cylinder 12 has a piston 16 located such that no gel base is located in the first compartment 18, while the first compartment 28 of the second cylinder 22 is filled with gel base. Utilizing air pressure, as controlled by device 52, with suitable air control valves, the gel base is cycled back and forth between the first and second cylinders 12 and 22 through the first and second conduits 38 and 40 and heat exchanger 36. During cycling of the gel base, a foaming agent is added to the gel base through the valve 42 in the first conduit 38, with the foaming agent comprising iso-pentane and iso-butane. During addition of foaming agent to the apparatus 10, the shaft coupling 50 is adjusted to allow for the volume of the foaming agent. 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: A method of making a post foaming gel, comprising the steps of: cycling a gel base among a first compartment of a first cylinder, a heat exchanger and a first compartment of a second cylinder; and introducing a foaming agent to the gel base while it is being cycled among the heat exchanger and the first compartments of the cylinders. An apparatus for making a post-foaming gel, comprising: a first cylinder (12) having a chamber (14) and a slideable piston (16) separating the chamber into a first compartment (18) to receive a gel base and a second compartment (20) to receive a compressed gas; a second cylinder (22) having a chamber (24) and a slideable piston (26) separating a chamber into a first compartment (28) to receive the gel base and a second compartment (30) to receive a compressed gas, with the first compartment of the first and second cylinders facing each other; conduits (38, 40) connecting the first compartments of the first and second cylinders to a heat exchanger (36); a pneumatic control system (74) for reciprocating the piston in the first and second cylinders (12, 22) to cycle the gel base through said conduits (38, 40) among the first compartment of the first cylinder, the heat exchanger and the first compartment of the second cylinder; ; 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; characterized by a shaft (34) connecting the pistons (16, 26) of the first and second cylinders; said shaft (34) comprising a pair of segments (34a, 34b) and including a slideable coupling (50) for slideably connecting the shaft segments to each other. The apparatus of claim 2 including a spring (68) for biasing the shaft segments away from each other.

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