FR2747886A1 - Flexible silicone moulds for baking pastries - Google Patents

Abstract

Hot or cold cured elastomers made of silicones are moulded to make flexible moulds, of mean thickness 1.5-2.5 mm, for the food industry particularly for the cooking or setting of foods.

Description

 The present invention relates to flexible molds based on silicones intended for the food industry and in particular for pastry making (sponge mold, cake mold, brioche, savarin, madeleine, financier mold, etc.).

 The molds of the aforementioned type have, for a long time, been made of metal (steel or aluminum) the application of a film of fatty substance (oil or butter) on their internal walls did not prevent their users from colliding when demoulding, adhesion and sticking problems significantly affecting the appearance of the final product.

 In addition, cleaning the molds thus soiled was always long and inconvenient and frequently required scraping operations favoring sticking and leading in the long run to damage to the mold and therefore to a decrease in its life.

 To solve these problems, it has been proposed to apply non-stick coatings, in particular polytetrafluoroethylene, to the internal walls of metal molds; in spite of its certain advantages, such an application has not proved completely satisfactory, in particular because of the fragility of the non-stick coatings and their great sensitivity to abrasion, the consequence of which is that they become unusable very quickly.

 In addition, the use of these non-stick coatings does not solve all the problems encountered by users during demolding, given the rigidity of metal molds: it is, in fact, often necessary, to extract the cooked product , to strike the bottom or the side walls of the mold, or even to pass the blade of a knife between the latter and the product.

 To overcome the aforementioned drawbacks, there has already been proposed, in accordance with document FR-A86 02 471, an assembly intended for cooking food and consisting of a tray of stainless steel or aluminum carrying a non-stick membrane. preformed formed by a weft of son or fibers of glass, carbon or ceramic impregnated or coated with a non-stick material, in particular silicone resin.

It was also proposed, in accordance with the document
FR-A-90 01 561, a membrane intended for deep-freezing and / or cooking of food products and consisting of a knitted weft of glass or ceramic threads comprising at least two silicone coatings, namely a first coating made with a silicone ensuring the rigidity of the material so that it is self-supporting and a second coating made with a flexible silicone with very high anti-adhesion, preferably with a very high coefficient of elongation.

 In addition to their non-stick nature, the molds described in these two publications have the advantage of being flexible, and of being able to deform during demolding, which greatly facilitates this operation; their particular configuration and their composite character make them however particularly expensive and do not allow them, moreover, not to adapt to all the geometries and in particular to the shapes comprising right angles.

 The present invention overcomes these drawbacks through the use of elastomers vulcanizing hot or cold and consisting of silicones for the manufacture, by molding, of flexible molds intended for the food industry and in particular for cooking. or freezing food.

The silicones which can be used in accordance with the invention must, of course, be edible; they can be in the form of reactive oils (cold vulcanizing elastomers - EVF), in particular of the type
RTV (Room Temperature Vulcanizing) or gums (hot vulcanizing elastomers - EVC).

 Given their lower price, EVCs are used, and in particular high molecular weight polymethylsiloxanes vulcanizing at around 150 to 1600C.

 By way of example, it is advantageous to use the product sold by the company RHONE POULENC under the name RHODORSILs reference 71-791.

 To allow vulcanization, these elastomers must, of course, be associated with a small proportion of vulcanization catalysts, in particular peroxides.

 According to another characteristic of the invention, 2 to 20 W by weight of a filler capable of improving the conduction of heat when cooking a food in the mold is added to the silicones.

 This filler can be constituted by a black dye, preferably by carbon black, for example the product sold under the reference MB-79 (SAFIC-ALCAN) or also by aluminum powder.

 It should be noted that the role of this filler is, in fact, double since it also makes it possible to color the silicone which is initially translucent, in particular in black or in gray in the case of aluminum powder.

 The invention also relates to a flexible silicone-based mold intended for the food industry and manufactured as described above.

 Such a mold is characterized in that it has an average thickness of the order of 1.5 to 2.5 mm, which gives it very great flexibility and a large capacity for deformation; moreover, the implementation of a molding process makes it possible to obtain extremely smooth and therefore highly non-stick surfaces, which avoids any risk of sticking of the cooked product on the walls of the mold.

 Another advantage of the molding process is linked to the fact that it makes it possible to reproduce all the forms of metallic molds existing today, including the most complicated and even those comprising right angles, for example plates provided with semi-spherical cells. .

 The mold, in accordance with the invention, is further distinguished by its ability to withstand a very wide range of temperatures from around -500C to + 3000C.

 It should also be noted that the mold in accordance with the invention may correspond to a sheet provided with a relief decoration making it possible to mold cookies intended for surrounding cakes; in accordance with this variant of the invention, the use of an aluminum powder filler proves to be particularly satisfactory.

 The invention also relates to a method of manufacturing by molding the above-mentioned flexible mold.

According to a first variation of the invention, this process is a compression molding process characterized by the succession of the following steps
preheating of the mold of a molding press to around 1000C
hot consisting of a punch and a die provided with a
footprint corresponding to the part to be molded, these two elements
elements being respectively fixed to the press plates,
fitting of the elastomer to be molded into the impression of the
matrix,
closing the mold and compressing the elastomer under a
pressure of the order of 240 tonnes,
keeping the mold closed for 4 to 10 min. so as to per
put the vulcanization of the elastomer,
opening of the mold and extraction of the molded part.

 This is a classic process used in a wide range of industries (aeronautics, armaments, automotive, ...) and whose different parameters are adapted to the specifics of the material to be treated and to the food industry.

According to a preferred variant of the invention, this process is a spray molding process characterized by the succession of the following steps
manufacture of a molding device consisting of an em
base fitted with a heating resistor cooperating with a
regulator and on which is fixed a molding imprint
male, preferably aluminum corresponding to the part to be
mold,
preheating to around 1000C of the mold footprint,
spray projection on this print of the elasto
mother to mold using a compressor gun,
retaining the elastomer on the heated molding impression
for 4 to 10 min. so as to allow the vulcanization of
the elastomer, extraction of the molded part.

 Such a method has the advantage of being simpler and of requiring less expensive equipment than compression molding, and therefore of enabling parts to be produced at lower cost.

 It should however be noted that, thanks to the use of a male molding imprint, the internal surfaces of the parts obtained are largely as smooth as those of the parts obtained by compression molding, and therefore these parts have similar advantages.

 According to another characteristic of the invention, a prior step of incorporating a filler and mixing is carried out on a cylinder mixer.

 This preliminary step, at the end of which the elastomer remains malleable, makes it possible to replastify the latter in order to facilitate its subsequent treatment by compression molding or by spraying.

 According to another characteristic of the invention, a final step of treatment in an oven of the molded part is carried out for approximately 16 hours at a temperature of approximately 100 "C.

 This operation makes it possible to avoid any reversion phenomenon causing degradation of the vulcanized silicone into shorter molecules, to neutralize the odors of rubber, and above all, to eliminate traces of catalysts which may have remained in the product after molding in order to make it food.

Claims (9)

10) Use of elastomers vulcanizing hot or cold and constituted by silicones for the manufacture, by molding, of flexible molds intended for the food industry and in particular for cooking or freezing food. 20) Use according to claim 1, characterized in that one implements silicones in the form of gums (elastomers hot vulcanizing - EVC) and preferably polymethylsiloxanes of high molecular weight vulcanizing at about 150 to 1600C. 30) Use according to claim 2, characterized in that a small proportion of a vulcanization catalyst, in particular a peroxide, is added to the vulcanizing elastomers when hot. 40) Use according to any one of claims 1 to 3, characterized in that there is added to the silicones, 2 to 20 W by weight of a filler capable of improving the conduction of heat during cooking. 'a food in the mold. 50) Use according to claim 4, characterized in that the filler is constituted by a black dye, preferably by carbon black. 60) Use according to claim 4, characterized in that the filler consists of aluminum powder. 70) flexible silicone-based mold intended for the food industry and manufactured in accordance with any one of claims 1 to 6, characterized in that it has an average thickness of the order of 1.5 to 2.5 mm.  8) A method of manufacturing by compression molding a flexible mold according to claim 7, characterized by the succession of the following steps  preheating of the mold of a molding press to around 1000C  hot consisting of a punch and a die provided with a  footprint corresponding to the part to be molded, these two elements  elements being respectively fixed to the press plates,  fitting of the elastomer to be molded into the impression of the  matrix,  closing the mold and compressing the elastomer under a  pressure of the order of 240 tonnes,  keeping the mold closed for 4 to 10 min. so as to per  put the vulcanization of the elastomer,  opening of the mold and extraction of the molded part. 90) A method of manufacturing by spray molding a flexible mold according to claim 7, characterized by the succession of the following steps  manufacture of a molding device consisting of an em  base fitted with a heating resistor cooperating with a  regulator and on which is fixed a molding imprint  male, preferably aluminum corresponding to the part to be  mold,  preheating to around 1000C of the mold footprint,  spray projection on this print of the elasto  mother to mold using a compressor gun,  retaining the elastomer on the heated molding impression  for 4 to 10 min. so as to allow the vulcanization of the elastomer,  extraction of the molded part. 100) Method according to any one of claims 8 and 9, characterized by the implementation of a prior step of incorporating a filler and mixing on a 9 cylinder mixer.  11) Method according to any one of claims 8 to 10, characterized by the implementation of a final step of treatment in an oven of the ground part for about 16 hours at a temperature of about 100 C.