EP0493197B1 - Process for molding a liquefiable material, especially soaps, and transparent or translucent soaps - Google Patents

Abstract

Process for moulding a liquefiable product, especially soap, according to which a chamber, bounded by at least one wall (4) of elastic material which is resistant to the temperature of the liquefied product, is made inside a rigid mould (1); the internal volume of the chamber (R) is less than that of the mould; the air is expelled from the chamber and it is filled with the liquefied product until it fills all the internal volume of the mould (1). The product contained in the chamber (R) is cooled in the mould and the product is removed from the mould. <IMAGE>

Description

The present invention relates to a process for molding a liquefiable material, in particular soap.

EP-A-321 179 proposes a process for molding, and optionally packaging simultaneously, a material such as soap. According to this method, at least partially a flexible material packaging is filled with the liquid or semi-liquid state, the packaging is closed in an airtight manner, the material is allowed to set mass and the material is stored in the packaging in which it was poured.

It is possible to compress the packaging during cooling between two flat surfaces or to introduce it into a mold so as to compress it.

The compression operations, or similar operations, essentially aim to ensure good contact of the material to be molded with the wall of the package, and to give the latter a shape other than that of a cushion which it would naturally take.

However, when a hot liquefied product is poured into a mold, or in its packaging, the product may, when it cools, have a significant shrinkage. The adhesion to the walls of the mold, or of the packaging, of the layer of material immediately in contact prevents this layer from following the shrinking of the mass of material. This results in significant shrinkage and appearance defects, such as hollows, which can be unacceptable. The shrinking is often accompanied by the formation of bubbles or cloudy areas in the product, which is unacceptable for transparent soaps.

This problem was not really addressed in EP-A-321 179, certain passages of which speak only of causing an extension of the envelope, for example an extension caused by heat, to better bring it into contact with the product. However, the difficulties created by shrinking the product remain silent, in particular when it comes to transparent soaps.

EP-A-0 299 113 describes a process in which products are molded in an elastic mold having the shape of an open bag.

The object of the present invention is to provide a process for molding a liquefiable product which avoids the formation of a necking and which remains economical while giving the finished product a beautiful appearance.

The present invention therefore relates to a process for molding a liquefiable product, in particular soap, characterized in that there is produced, inside a rigid mold, a chamber limited by at least one wall of material elastic resistant to the temperature of the liquefied product; that the interior volume of the chamber, at rest, is less than that of the mold in a proportion such that the wall of the chamber, to reach the volume of the mold by swelling, must undergo an elongation at least equal, in absolute value, to shrinkage of the molding product; that the air is expelled from the chamber with a wall of elastic material; that the chamber is filled with the liquefied product until, thanks to the elasticity of its wall, the chamber fills the entire interior volume of the mold; that the product contained in the chamber is cooled in the mold, and that the product is removed from the mold.

Preferably, the interior volume of the chamber at rest is such that the elongation of the wall of the chamber is at least 50% when it is filled against the walls of the mold.

The shape of the resting chamber can be substantially homothetic to that of the mold so that the elongation in the different directions of the space is relatively constant.

According to the invention the elastic wall of the chamber will, at the end of filling, uniformly line the mold, then during cooling the elastic wall exerts a practically uniform pressure on the product which it contains which shrinks during cooling . The product contained in the chamber with elastic wall will therefore peel off uniformly from the wall of the mold. This prevents the formation of shrinkage and bubbles. After assembly, a bread is obtained, having the shape of the mold.

According to the invention, to expel air from the chamber with elastic wall, it is possible either to exert a slight pressure in the mold, or to make a partial vacuum in the chamber with elastic wall.

To fill the chamber from a source of liquefied product, the interior of the mold can be placed under partial vacuum; thanks to its elasticity, the wall of elastic material of the chamber expands while filling and will occupy the entire interior volume of the mold. It is also possible to exert pressure on the liquefied product so that the chamber fills and occupies the entire interior volume of the mold.

The product is then cooled. The mold can be allowed to cool in the ambient atmosphere. The cooling process is preferably accelerated either by circulating air around the mold, or by using a double jacket mold and by circulating cold water in this double jacket. It is understood that the cooling temperature is higher than the temperature where the elastic material of the wall of the chamber is likely to freeze.

The chamber may consist of a pocket made of elastic material, in particular latex. In this case, the wall of the chamber is confused with that of the pocket.

The method with a latex bag can be applied to any product having a melting or liquefaction temperature at most equal to 85 ° C. It can be used for example for molding candles or a lipstick grape.

According to another embodiment, the elastic wall of the chamber comprises at least one sheet or plate of elastic material, in particular elastomeric material, placed in the imprint of at least one half-shell of the mold. Such a sheet or plate of elastic material can be provided in each imprint of the half-shells.

According to a preferred variant, of this embodiment, the material of the elastomer sheet is chosen from silicones. The elastomer wall preferably has a thickness of about 0.6 mm to 0.7 mm.

Advantageously, the rigid mold is provided with at least one opening, or a recess, in its side wall allowing the elastic sheet to expand during filling, in particular when hot under pressure.

The method of the invention is particularly advantageously applicable to the molding of soaps, preferably transparent or translucent soaps.

The mold used according to the invention can have any shape, ovoid, pebble, sphere, cube, or, more particularly, a shape of rectangular parallelepiped with rounded corners.

The interior volume of the mold can have different values. It is for example in the case of molding soaps, advantageously between 1 ml and 100 ml.

It is constructed of sufficient material rigid to withstand the pressures exerted during the molding process.

According to a particular embodiment, in the case where the chamber is constituted by a pocket made of elastic material, the mold is constituted by a rigid box which serves as packaging for the bread of product contained in the pocket. In this case, it is not necessary to unmold the product contained in the flexible pouch and then put it in a package. This avoids a product recovery operation.

The pocket used according to the invention can be made of natural or synthetic rubber. The rubber used must have an elongation at least equal to the constriction, that is to say, in the case of the molding of soap, at least equal to 5%.

The invention also relates to a soap, transparent or translucent, in particular obtained by the method of the invention, and characterized in that it is wrapped in a pocket of elastic material, having undergone elongation.

Pockets having various colors can be used, but preferably a pocket made of transparent or translucent material is used. The pocket advantageously includes a cutting primer to allow the envelope to be easily torn before the use of the solidified product roll.

The invention consists, apart from the arrangements set out above, of a certain number of other arrangements which will be more explicitly discussed below in the detailed description of particular embodiments, description given by way of explanation, and not limiting, with reference to the accompanying drawings.

Figures 1 a to 7 a of these drawings illustrate a first embodiment of the method of the invention.

Figures 1b to 7b illustrate a second embodiment.

Figures 1 c to 4 c illustrate another embodiment.

Figure 1 d illustrates an alternative embodiment.

Figure 8, finally, illustrates a soap obtained with the mold of Figure 1 d .

In the process of FIGS. 1 a to 7 a , in a first stage illustrated by FIGS. 1 a and 2 a , we take a mold 1 composed of two rigid half-shells 2, 3 mounted on a hinge (not shown). The half-shell 2 is provided with a tube 6 passing through the thickness of the mold.

Opposite the articulated part of the half-shells, recesses are provided in the opposite faces of the half-shells so as to form a sort of passage or tubing t (FIG. 2 a ) when the half-shells are applied. one against the other.

A pocket 4 made of elastic material, in particular natural latex, the volume of which in the free state is much less (for example at least 10 times less) than the volume of the internal space V of the mold, is placed in this space V. By volume at rest, or in the free state, of the bag 4, is meant the volume of liquid, or gas that can contain this bag without undergoing expansion or elongation. The pocket 4 is provided with a sort of neck g , forming a mouth, which passes through the passage t and which allows the pocket to be held. The pocket 4 determines, by its internal volume, a chamber R.

The mold 1 is closed so as to fix the pocket using a seal (not shown) by its mouth (see FIG. 2 a ).

To expel the air from pocket 4, we send via the pipe 6 a gas under pressure. When the bag 4 is completely flattened, it is placed in communication with a source 5 of liquefied product (FIG. 4 a ) (for example a funnel filled with product) and the tube 6 is closed.

A partial vacuum is then made in the interior volume V of the mold by putting it in communication with a vacuum pump via the tube 6.

The bag 4 fills and expands until it occupies the entire interior volume of the mold 1 (FIG. 6 a ). The liquefied product is then allowed to cool and harden. It is possible to exert a slight overpressure between the interior wall of the mold and the bag 4 by introducing a pressurized gas through the tube 6 so as to detach the bag 4 from the mold and to accompany the product during its shrinking.

When the molded product is cooled and solidified, the mold 1 is opened and the loaf P of formed product is removed which is wrapped in the bag 4. Finally, the excess product is cut at the orifice t remaining and the neck g of the pocket. The bread P of product wrapped in the bag 4 is sold as is, the bag serving as packaging, or is placed in an additional packaging such as box or paper.

The process illustrated schematically in Figures 1 b to 7 b is similar to that illustrated in Figures 1 a to 7 a , except that the internal volume of the mold 10 is not pressurized.

The numerical references of identical elements or playing roles analogous to elements of FIGS. 1 a to 7 a , are equal, in FIGS. 1 b to 7 b , to the sum of the number 10 and the reference used in FIGS. 1 a to 7 a ; their description is not repeated.

At the first stage, a pocket 14 is introduced into a mold 10 provided with a vent 16 and the mold 10 is closed (FIGS. 1 b , 2 b ). Vacuum is then made in the pocket 14 by putting its mouthpiece g into communication with a vacuum pump (FIG. 3 b ). When the pocket is flattened, its mouth is placed in communication with a source of liquefied product 15 (FIG. 4 b ). Pressure is exerted on the liquefied product so as to fill the bag 14 by expanding it until it completely fills the interior volume of the mold 10. As the bag 14 expands and elongates in in all directions, the air contained in the interior volume V of the mold is expelled by the vent 16 (FIG. 5 b ).

Then the supply of liquefied product to the bag 14 is stopped and the product is allowed to cool and solidify (FIG. 6 b ). When the liquefied product is solidified in the form of a bread P contained in the casing 14, the mold is opened and the casing 14 containing the bread P is removed.

With the method of the invention, during the cooling of the product, the wall of the pocket, because of its elasticity, will follow the product, in particular the soap, keeping any imprints of the mold while remaining stuck to the product.

The pouch filling orifice, determined by the passage t , has a reduced section so that the loss of product corresponding to the part of product solidified in this passage is reduced. In addition, the area of the finished product not covered by the pocket, corresponding to the removal of said neck portion g , is also reduced. The existence of this zone is however advantageous since it constitutes a cutting initiation facilitating the withdrawal of the envelope when the product is going to be used.

According to the embodiment illustrated in FIGS. 1 c to 4 c , the walls 24 a , 24 b of the chamber R are constituted by two sheets, or plates, or membranes of elastic material, in particular elastomer material. These sheets (or plates) are placed in the respective imprint of the two half-shells 22, 23 of the mold. When the mold 20 is closed, the edges of the elastic walls 24 a , 24 b are joined and the chamber R communicates with the outside only through the passage t formed by recesses provided in the opposite faces of the half-shells 22, 23. Each half-shell is provided with a tube 26 passing through the thickness of its wall in a central zone.

If necessary, the mold is closed so as to expel the air from the interior of the mold by putting it in communication with a vacuum pump via the tube t (FIG. 1 c ).

When the vacuum is reached, the tube t is placed in communication with a source of liquefied product 25 (FIG. 2 c ). Pressure is exerted on the liquefied product so as to fill the mold until the two elastic walls 24 a , 24 b , adhere perfectly to the walls of the mold. The tubes 26 can be connected to the suction of a vacuum pump to facilitate the application of the elastic walls 24 a , 24 b against the walls of the mold.

Before filling, the interior volume of the chamber R, delimited by the elastic walls 24 a , 24 b , unexpanded, is approximately 5% to 7% less than the total volume of the mold cavities 20.

As the elastic walls 24 a , 24 b expand, the air contained in the gap between the membranes and the internal wall of the mold is expelled by the tubing 26. In one embodiment, not illustrated, the tubing 26 is constituted by a recess (or an opening) of relatively large dimensions (for example with a diameter of the order of 2 cm or 3 cm), communicating with the outside through the side wall of the mold; the elastic wall is thus in direct communication with the atmosphere. This recess allows the elastic sheet to expand during hot filling under pressure.

The supply of liquefied product is then stopped and the tube t is hermetically closed. The product is allowed to cool and solidify (Figure 3 c ). A slight pressure can be exerted between the interior wall of the mold and the film or the elastomer plate by introducing a pressurized gas through the pipes 26 so as to peel off the elastomer membrane from the mold and to accompany the product during its shrinks when it cools.

When the liquefied product is solidified in the form of a bread P, the mold is opened and the bread P is removed (FIG. 4 c ).

Finally, the excess product remaining and the carrot g are cut at the filling orifice t .

The bar of soap obtained can then be engraved by striking.

Preferably, the two elastic walls 24 a , 24 b remain attached to the half-shells 22, 23 of the open mold. However, provision could be made for the elastic walls 24 a , 24 b to remain around the bar of soap P to form a package.

In the embodiment illustrated in FIG. 1 d , the chamber R is limited on one side of the joint plane of the half-shells 32, 33 of the mold 30 by an elastic wall 34 constituted by a sheet, or the like, of elastic material, in particular elastomeric material placed in the cavity of the half-shell 33. The rigid wall w of the cavity the other half-shell 32 comes directly into contact with the molded product. This wall w advantageously comprises patterns, letters, etc., in relief or in hollow, suitable for directly etching the product P1 during molding, without requiring a subsequent striking.

Due to the presence of the single wall 34 for monitoring the constriction, a bar of slightly asymmetrical soap P1 is obtained, as illustrated in FIG. 8.

Tubing 36 is provided in the wall of the single half-shell 33, the imprint of which is equipped with the elastic wall 34. The pressure for following the constriction is located only on the face of the bread P1 in contact with the elastic wall 34.

The internal volume enclosed by the elastic wall 34, not expanded, and the wall w , when the mold 30 is closed, is approximately 5 to 7% less than the total volume of the mold cavities 30.

Claims (16)

1. A method for moulding a liquefiable product, in particular soap wherein:

   - a chamber (R) is made which is bounded by at least one wall (4; 14; 24a, 24b; 34) made of an elastic material withstanding the temperature of the liquefied product;

   - the air is evacuated from the chamber (R);

   - the chamber (R) is filled with the liquefied product;

   - the product contained in the chamber (R) is cooled;

   - and the product (P, P1) is removed from the mould;
   characterized in that

   - the chamber (R) is obtained inside a rigid mould (1, 10, 20, 30). the internal volume of the chamber (R), at rest, being smaller than that of the mouldy in such a proportion that, in order to attain the volume of the mould by inflation, the wall of the chamber must be subjected to an elongation at least equal to the contraction of the product to be moulded in absolute terms;

   - that the chamber (R) is filled with the liquefied product until the chamber (R) fills the whole of the internal volume (V) of the mould, thanks to the elasticity of its wall;

   - and that the product contained in the chamber (R) is cooled in the mould (1, 10, 20, 30).
2. A moulding method according to claim 1, characterized in that the internal volume of the chamber (R) at rest is such that the elongation of the wall of the chamber is at least 50% at the time of its filling against the walls of the mould.
3. A moulding method according to claim 1 or 2, characterized in that the shape of the chamber (R) at rest is substantially similar to that of the mould, so that the elongation in the different directions of space is substantially constant.
4. A moulding method according to one of the preceding claims, characterized in that, in order to fill the chamber (R) from a source (15) of the liquefied product, pressure is exerted on the liquefied product.
5. A moulding method according to one of the preceding claims, characterized in that a mould (1, 10, 20, 30) is used whose wall includes at least one small tube (6, 16, 26, 36) which makes it possible in the course of the cooling to exert slight pressure between the internal wall of the mould (1) and the elastic wall (4, 14; 24a, 24b; 34) of the chamber (R).
6. A method according to one of the preceding claims, characterized in that the chamber (R) is constituted by a pouch (4, 14) made of an elastic material, in particular of latex.
7. A method according to one of claims 1 to 5, characterized in that the elastic wall (24a, 24b; 34) of the chamber (R) comprises at least one sheet or plate made of an elastic material, in particular an elastomeric material, placed into the recess of at least one half-shell (22, 23; 33) of the mould.
8. A method according to claim 7, characterized in that the wall made of an elastomer is constituted by silicone.
9. A method according to claim 7 or 8, characterized in that the wall made of an elastomer has a thickness of approximately 0.6 to 0.7 mm.
10. A method according to one of the preceding claims, characterized in that the mould has at least one opening in its side wall permitting the dilatation during the filling.
11. A method according to one of claims 7 to 9, characterized in that a sheet or plate of an elastic material constituting an elastic wall (24a, 24b) is provided in each cavity of the half-shell of the mould (20).
12. A method according to claim 7 or 11, characterized in that the internal volume enclosed by the undilated elastic wall (24a, 24b; 34) is less than approximately 5 to 7% of the total volume of the recesses of the mould (20; 30).
13. A moulding method according to one of the preceding claims, characterized in that a mould (1, 10, 20, 30) is used having an internal volume comprised between 1 ml and 100 ml.
14. A moulding method according to one of the preceding claims, characterized in that a mould is used constituted by a rigid box which serves as packing for the tablet (P) of the product contained in the pouch.
15. A transparent or translucent soap, characterized in that it is wrapped up in a pouch (4, 14) made of an elastic material having been subjected to elongation.
16. A soap according to claim 15, characterized in that the pouch enfolding the soap has an incipient cut.

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