MXPA99010530A - Process for the production of a detergent composition - Google Patents

Abstract

A process for forming detergent bars comprising applying pressure to a detergent composition contained within a mould cavity. The detergent composition in the mould is in a substantially fluid or semi-solid state and the mould is substantially full before the pressure is applied.

Description

As a material is distributed to the cavity of a mold, flow fronts of the material in the cavity are created, as the material is added and the cavity is filled. The lines of union or welding in the final bars are a result of interfaces or interconnections between the flow fronts of the * f detergent material within the mold cavity, which tend to be joined together. Such bonding or welding lines may be visible to the consumer, and "may lead to weakness of the bar, which in turn may lead to cracking, in use." Therefore, there is a need for a process for the formation of detergent compositions. In bars, of good quality, which have good appearance and good physical characteristics, such process should prevent the imperfections that are associated with shrinkage and should allow the detergent composition to be fed to the mold in any desired physical state, and the bar formed in any desired way, with a well-defined logo, if required., document W096 / 25481 (Unilever) and the US Patent No. 2,813,078 (American Cynamid) discloses processes for the preparation of blocks or solid tablets of detergent compositions by compressing granular or pelletized material, respectively, in a molding press. US Patent No. 2,987,484 (Procter &Gamble) discloses a closed matrix T-molding process in which a fluid, non-soap, hot melt mixture of synthetic detergent and a binder vehicle is injected rapidly through an orifice small within a substantially closed matrix, the fluid mixture is capable of solidifying in a substantially uniform form.

The present inventors have found that if a pressure is applied to a detergent composition in a substantially fluid or semi-solid state contained within a mold cavity, then the problems associated with the shrinkage of the detergent composition as it cools can be reduced. . In addition, the problems encountered when forming bars from semi-solid material, for example, joining lines or welding, can be diminished and better definition of the logo can be obtained.

BRIEF DESCRIPTION OF THE INVENTION According to a first aspect, the present invention provides a process, for the formation of detergent bars, comprising the application of pressure to a detergent composition contained within a mold cavity, characterized in that the mold cavity is substantially filled when the pressure is applied, and the detergent composition is in a substantially fluid or semi-solid state when the pressure is first applied.

In order to maintain the total volume of the detergent material in the cavity of the mold and to improve the reproduction of the shape, the additional detergent composition can be distributed to the mold cavity as the volume of the detergent composition in the cavity decreases. of the mold, as it cools and shrinks. Thus, according to a second aspect, the present invention provides a process for the formation of detergent bars, comprising feeding a detergent composition into a mold cavity until the latter is substantially full, and then creating a pressure on the detergent composition in the mold cavity, by applying a pressure to a feed of a detergent composition in fluid contact with the material contained within the cavity. If the detergent composition that is delivered to a mold contains an amount of a compressible material, for example, a gas, then when a pressure is applied to the detergent composition contained within the mold, the volume of the compressible material will be reduced. If the mold cavity is then closed, the subsequent reduction in the volume of the detergent material (eg shrinkage or cooling) makes it possible for the volume of the compressible material to increase., thus maintaining the total shape and volume of the bar. Thus, according to a further aspect, the present invention provides a process for the formation of detergent bars, comprising the application of a pressure to the detergent composition contained within a mold cavity, characterized in that the detergent composition contains a gaseous component -fe1-compressible dispersed in it. Unless specified more generally, references herein to the invention or to any preferred features apply to all aspects of the invention.

DETAILED DESCRIPTION OF THE INVENTION The detergent compositions that are to be distributed to the mold can be of any shape, capable of being distributed to the mold. For example, the composition may be in a substantially fluid (e.g., molten, molten dispersion, liquid), substantially semi-solid or quasi-solid form, as long as the composition is plastic enough to allow the material to be distributed to the mold as it could be understood by a person of experience in the art. The present invention considers that detergent compositions that are not readily movable and voidable (for example, which are not susceptible to emptying) can be fed into a mold and formed in the form of bars by techniques such as injection molding. Preferably, the detergent composition entering the mold cavity is in a substantially fluid or semi-solid state. A detergent composition can be considered as in a semi-solid state if sufficient structure is present in the composition, so that it no longer behaves as a simple liquid, as would be understood by one of skill in the art. The term "melt", as used hereinafter, may include the detergent compositions in a substantially fluid or semi-solid state Where the pressure applied to the mold is applied over a small cross-sectional area, for example, in the gate of the mold, it will be clear to the skilled person that the benefits of the present invention will not be obtained if the material in the mold cavity is allowed to solidify to a very high degree before pressure is applied. The mold is in a substantially fluid or semi-solid state when the pressure is first applied.The material must be such that it is capable of transmitting the pressure applied for example in the gate of the mold cavity, through the cavity in the mold. Preferably, pressure is applied to the detergent material contained within the mold cavity while at least some of the detergent material therein is solidifying. The mold is substantially full when the pressure is applied. The molds used in the manufacture of detergent bars typically comprise a cavity defined by a rigid material. Typically, a mold comprises two complementary, rigid (or more) matrix parts which in the coupling define a cavity corresponding to the overall shape of the article to be manufactured in a casting or injection molding process, and a gate. The detergent melt is fed into the mold cavity through a hole or "gate" in the mold. The gate opens on one side towards the cavity and can be opened on the other side towards a neck (eg, a small channel) through which the detergent composition can be fed into the mold cavity. The neck can be designed to retain a relatively large amount of detergent material, for example up to 20% of the volume of the mold cavity, if desired. The molds are generally constructed of materials with high thermal conductivity, for example aluminum. This is to help cool the melt and therefore shorten the bar release times. The mold will be designed so that it can withstand the applied pressures, considered, without leakage, for example, by the provision of suitable sealing means such as "flanges" and notches, gaskets, etc. between the parts of the mold. The mold will also be capable of being sealed in the gate, either by contact with the means for the distribution of detergent material, or by means of a separate closing device such as a valve or plug. In a conventional pouring process, a molten detergent in a substantially fluid state and generally at a high temperature, it is fed to a mold until the mold cavity is full. If a detergent composition that is not in a fluid form is to be distributed, pressure can be applied to the detergent composition in order to distribute it to the mold cavity. Once inside the mold cavity, the detergent material is cooled, and this tends to result in a reduction in the volume of the detergent material. This can result in any of the following occurring: the detergent material being pulled away from the mold wall, often preferably over a part of the mold surface; that the detergent material shrinks away from one or more internal imperfections in the bar, leaving an "orifice" or empty spaces inside the bar; that the detergent material shrinks in the gate, leaving a depression there (a "sink mark"). The loss of contact with the mold wall is visible as dimples or wrinkles on the surface of the bar. Any depression in the gate is also easily observed. The presence of internal imperfections of the rod can be demonstrated not by intrusive X-ray transmission techniques. A problem particularly associated with the distribution of semi-solid detergent compositions to a mold is the formation of "lines of union or welding" on the bars . Without being bound by any theory, it is believed that as a material is distributed to a mold cavity, fronts of the material flow in the cavity are created, as the material is added and the cavity is filled. The connecting lines in the end bars are a result of the interfaces or interconnections between the detergent material flow fronts within the mold cavity, which have not been properly mixed together. Such bond lines may be visible to the consumer, and may lead to weakness of the bar, which may in turn lead to breakage or cracking in use. These bond lines are also detectable by X-ray techniques. The mold could be filled to the gate (for example, only the mold cavity can be filled) or more material can be added which will settle, for example, in the neck of the mold. Where a mold cavity is filled and then immediately disconnected from the feed means, any of the aforementioned phenomena may occur. If the material at the entrance of the mold cavity, or in the neck of the mold rapidly solidifies, the subsequent shrinkage of material within the cavity can result in internal voids and / or surface defects.

If the entry point to the mold cavity remains fused, it is likely that there are depressions / imperfections in the position of the gate. According to the process of this invention, a pressure is applied to the detergent composition contained within the mold cavity, once the cavity is filled. The pressure can be applied by any suitable device, for example, a piston or hydraulic or pneumatically driven piston. In a preferred embodiment, a pressure can be applied to the detergent composition fed in fluid contact with the detergent composition in the mold cavity, in order to force more material into the mold cavity, and thus to put the detergent composition in the mold cavity under pressure. The cavity of the mold can then be sealed or closed and the material contained therein is allowed to cool and solidify. The feed of detergent material to which a pressure is applied may be the same or a detergent composition different from that which is contained within the mold cavity. Instead of closing or sealing the mold or cavity of the mold once a pressure has been created on the material in the mold, the pressure can continue to be applied on the detergent composition in the mold cavity, by continuing to apply pressure to a composition detergent fed in fluid contact with the detergent composition contained within the mold cavity. Continuing to apply pressure to a powered detergent composition can mean maintaining the pressure existing on the material in the mold cavity, or even increasing it. Of course, if pressure is applied to a detergent feed in order to create a pressure on the material contained within the mold cavity, then the detergent feed must be able to transmit that pressure, for example, this is preferably in fluid or semi-solid state. In this regard, it may be necessary to maintain the detergent feed above a minimum temperature by heating the latter. Of course, any heating means present should not interfere to a significant degree with the solidification process taking place in the mold, for example these should not heat the mold or material in the mold to any significant degree, but only the feed out of the mold. In a preferred embodiment, a molten detergent is fed to a mold comprising a cavity, a gate and a receptacle for the composition of the detergent on the other side of the gate (e.g., a neck or reservoir) so that the cavity is filled and there is some "excess" detergent composition in the receptacle. Subsequently a pressure is applied to the detergent composition in the receptacle using a suitable pressure applying means, such as, for example, a plunger or piston.

In the case of an injection molding process where a pressure is applied to a feed of detergent composition in order to feed it into a mold, the pressure applied to the feed of the detergent composition to distribute it towards the mold cavity, can continue to be applied to the feed of the detergent composition after the mold cavity has been filled. The pressure created in the mold cavity by the processes of the present invention can be high. For example, such pressures may be up to 6.89 MPpa (1000 p.s.i.). Typically, pressures from 0.34 to 5.52 MPa (50 to 800 p.s.i.) may be employed. The pressure does not need to be constant with the time for which it is applied, for example it can increase or decrease. All the figures present are in MPA (psig) for example the level above the atmospheric pressure. The time over which the pressure is applied to the detergent composition after the mold cavity has been filled will vary depending on the, among other things, the properties of the detergent composition that is distributed to the mold, and the cooling regime employed. For example, compositions that are distributed to a mold in a substantially fluid state and at high temperatures may require a longer time than compositions that are distributed to a mold in a substantially semi-solid state and / or at a lower temperature. t Typically, the time is less than 2 minutes, preferably less than 1 minute, more preferably less than 30 seconds, and still more preferably less than 10 seconds. The time can be very short, for example, less than 1 second. The mold can be sealed while the pressure is being applied, for example by a valve or plug, or the pressure can be applied for a period at least long enough to allow the material at the point of entry into the mold (for example the gate) solidifies substantially, for example, allowing a seal to be formed in the gate, so that any additional pressure applied could no longer be transmitted to the material within the mold cavity. Without being bound by any theory, it is believed that when a detergent composition enters the cavity of a mold, the material closest to the walls of the mold cavity will cool and solidify more quickly than the material in the center of the cavity. of the mold. This results in the formation of a "shell or shield" around a more molten core. If the temperature of the mold is lower than the melting temperature when the mold is filled, this shell or shield is formed very quickly. Since there is no cold metal wall in the gate, the shell will tend to be thinner, and complete or even not present here. Once the "shell of the wall" has been formed and is relatively rigid to the rest of the melt, the additional reduction in volume will therefore tend to act on the gate. The melt in the gate will be pulled into the mold cavity. If the molten material is available outside the mold cavity in the gate, for example, in a neck, it will be pulled into the mold cavity. Yet another method, by which a pressure can be created on the material in the mold cavity, is by sealing or closing the cavity after it has been substantially filled, and then reducing the volume of the cavity.

This could be achieved, for example, by the movement of a wall of the mold cavity, or part thereof, for example, the logo on the inner side of the mold could be moved further into the cavity. The last method has the added advantage that it can improve the definition of a logo. In an alternative to seal or close the mold after filling, an external pressure on the detergent composition in the cavity could be maintained at any exit / entry point of the mold cavity, such as the gate, in order to maintain or even increase the pressure on the material contained within the cavity, as the volume of the cavity is reduced. The present invention also provides partial filling of a mold cavity with a detergent composition, and then reducing the volume of the mold cavity until the detergent composition fills the volume of the cavity and a pressure is created on the material therein. In a preferred embodiment, the detergent composition to be formed into sticks contains a compressible component or various compressible components, such as, for example, a gas. The detergent composition may be aerated or there may be a gas present as a result of a manufacturing process (eg, a mixing step or as a result of a chemical reaction). The volume of the gas at ambient conditions may be sufficient to create floating rods, for example, or it may be small enough not to be detectable by the consumer, for example less than 5% by volume, preferably less than 2% by volume. The detergent composition containing a compressible gaseous component is distributed to a mold cavity until the cavity is substantially full and a pressure is then applied to a feed of detergent composition in fluid contact with the detergent composition in the mold, in order to force more material into the mold cavity. The compressible component (eg gas) in the detergent composition in the mold cavity will be compressed and pressurized, and more detergent material will enter the mold cavity. The mold can then be either sealed or closed, or the pressure can be maintained on the detergent composition in fluid contact with the material within the mold cavity for a period of time, as previously described. As the "non-compressible" material inside the cavity cools and decreases in volume, the volume occupied by the compressible component will increase. In still another aspect, the present invention provides a detergent stick obtainable by the process of the present invention. By "detergent bar" is meant a solid shaped object, such as a tablet, cake or bar in which the level of active surface agent, which comprises soap, active synthetic detergent or a mixture thereof, is at least 5% by weight. % by weight based on the bar. The detergent bar may also comprise benefit agents for imparting or maintaining desirable skin properties. For example, wetting agents may be included. The detergent compositions may comprise homogeneous components or mixtures of components, or may comprise suspended or dispersed material in a continuous phase.

EXAMPLES E ng A detergent formulation A was formed in detergent sticks by an injection molding process. The detergent composition was fed into a mold cavity by means of an injection device comprising an injection chamber, an actuator, and a nozzle. The detergent composition A was in a semi-solid state when it entered the mold cavity, at a temperature of 50 to 55 ° C. In all runs, the mold was at room temperature before filling, and cooling was effected by packing C02 around the outside of the mold for the specified period of time and then holding the mold at room temperature for an additional 5 minutes.

Formulation A was as follows:% in active weight Fatty ester directly esterified 27. . 8 Sodium stearate 14,. 6 Propylene glycol 17.8 Stearic acid 12.8 PEG 8000 9.7 Cocoamidopropi lbetaine 4.9 Paraffin wax 2.9 Sodium Isethionate 0.4 Water 5.6 Minor additives (preservatives, perfume, 2.5 color, etc.) TOTAL 100.0 The "retention time" referred to in Table 1 is the "period of time over which the pressure continues to apply to the feed of the composition-detergent in the injection chamber, after the mold cavity had been filled. After the retention time elapsed, the mold was disconnected from the feed medium.The pressure measured in the injection chamber at a point just above the inlet to the nozzle is recorded as the maximum injection pressure in Table 1 The average pressure within the mold cavity (for example in a sidewall) over the period of "retention time" is recorded as the average mold pressure in Table 1. These runs illustrate that the surface quality of the bars they can be improved by applying a pressure to a detergent composition in a mold, no binding lines were observed in any of the bars.

TABLE 1 10

Claims (6)

RE I INDICATIONS

1. A process for the formation of detergent bars, comprising the application of pressure to a detergent composition contained within the cavity of a mold, characterized in the process because the mold cavity is substantially full when the pressure is applied, and the detergent composition it is in a substantially fluid or semi-solid state when the pressure is first applied.

2. A process according to claim 1, wherein pressure is applied to the detergent composition contained within the mold cavity, while at least part of the detergent composition is solidifying.

3. A process according to claim 1 or claim 2, wherein the pressure on the detergent composition contained within the mold cavity is created by applying a pressure to a feed of a detergent composition, said feed being the composition of the composition. detergent in fluid contact with the material inside the cavity.

4. A process according to any of the preceding claims, wherein the detergent composition contained within the mold cavity contains a compressible gaseous component, dispersed therein.

5. A process according to any of the preceding claims, wherein the mold is sealed while the pressure is being applied.

6. A process according to any of the preceding claims, wherein the time in which the pressure is applied to the detergent composition contained within the mold cavity, is less than 2 minutes.