FR3065003A1 - PROCESS FOR PRODUCING WAX FOAM - Google Patents

Abstract

A process for producing a wax foam, comprising the steps of: - injecting a wax-based melted mixture and a compound to be incorporated into the mixture in at least one static mixer (4), - cooling the foam obtained at the outlet static mixer.

Description

® FRENCH REPUBLIC

NATIONAL INSTITUTE OF INDUSTRIAL PROPERTY © Publication number:

(to be used only for reproduction orders)

©) National registration number

065 003

53035

COURBEVOIE © Int Cl ⁸ : C 08 J 9/30 (2017.01), C 08 L 91/06, B 29 B 7/32, 7/82, C 11 C 5/00

A1 PATENT APPLICATION

©) Date of filing: 07.04.17. ©) Applicant (s): DENIS ET FILS SAS Company by ©) Priority: simplified actions - FR. @ Inventor (s): DOUDARD KARINE, LOISEL CATHERINE, ARHALIASS ABDELLAH, LEGRAND (43) Date of public availability of the JACK, POULIQUEN MARIE and SAINT-JALMES SYL- request: 12.10.18 Bulletin 18/41. VAINE. ©) List of documents cited in the report preliminary research: Refer to end of present booklet (© References to other national documents ©) Holder (s): DENIS ET FILS SAS Joint-stock company related: simplified. ©) Extension request (s): ® Agent (s): CABINET NONY.

PROCESS FOR THE MANUFACTURE OF A WAX FOAM.

©) Method for manufacturing a wax foam, comprising the steps of:

- inject a molten wax-based mixture and a compound to be incorporated into the mixture into at least one static mixer (4),

- cool the foam obtained at the outlet of the static mixer.

FR 3 065 003 - A1

i

PROCESS FOR PRODUCING WAX FOAM

The present invention relates to methods of manufacturing candles, in particular decorative ones.

Chinese patent application CN 101463290A discloses a candle based on wax foam, the foam being obtained using a rotary agitator. The mixture subjected to stirring comprises, for example, from 90 to 95% of paraffin, from 1 to 5% of polypropylene, and from 1 to 5% of foaming agents.

Application CN 102358868A also discloses a method of manufacturing a wax foam using a rotary agitator.

Utility model CN 202717762U discloses a machine for making wax foam comprising a tank provided with a rotary agitator. A microcomputer control system adjusts the speed of the agitator and the temperature.

Application CN 1023 58869A discloses a wax foam forming machine, comprising a rotary agitator. The speed of rotation varies depending on the manufacturing step.

Publication CN 1478876A discloses a candle comprising as an expanding agent trichlorotrifluororoethane.

Publication CN 1715386A discloses a process for manufacturing wax foam, the foam being obtained by stirring using a rotary agitator. The mixture used may contain polyethylene.

There is a need to further improve the candle manufacturing processes, in particular in order to reduce the amount of combustible material used to make the candles and / or facilitate the incorporation therein of scented, deodorant and / or insecticide active ingredients.

The invention meets this need through a process for manufacturing a wax foam, comprising the steps of:

- inject a molten wax-based mixture and a compound to be incorporated into the mixture into at least one static mixer,

- cool the foam obtained at the outlet of the static mixer.

The compound to be incorporated is preferably a gas, in particular air.

By “wax-based mixture” is meant a mixture containing at least one wax.

The invention offers multiple advantages.

First, the invention reduces the amount of wax used to make the candles, and therefore reduces their carbon footprint. The invention makes it possible to produce larger candles for a given weight of mixture, compared to candles which are not expanded.

In addition, the invention makes it possible to avoid using a rotary agitator to make the candles, which is advantageous from an energy point of view. The static mixer can be made compactly, and the installation of an intermediate tank downstream of the mixer is not necessary, which reduces the size of the candle manufacturing installation. For an equivalent number of candles produced, the least amount of mixture also reduces the energy expenditure to melt the mixture.

The working temperature can be lower than the temperature of the mixture when the wax is not full; this results in lower energy expenditure and increased safety for operators, since the risk of burns is reduced. The expansion increases the mechanical resistance of the mixture. The invention makes it possible to use a mixture which, in the absence of expansion, would have insufficient mechanical strength for the production of a candle by virtue of its melting point. The candle has increased heat resistance.

The invention also makes it possible to produce candles which are less subject to the phenomenon of exudation compared to candles produced with a conventional non-expanded wax, which is advantageous from the point of view of appearance and touch. The tendency to exudate being reduced, it is possible to reduce the quantity of wax, in particular paraffin, in favor of oils, in particular vegetable oils, in the mixture. This makes it possible to widen the range of raw materials that can be used for formulation, and in particular to make candles if desired with mixtures of 100% vegetable materials, with less refined or less treated, or recycled materials.

Wax foam also has fewer apparent crystallization defects than conventional wax, because the thermal cycle is different, which reduces manufacturing waste.

Preferably, the mixture comprises at least one shear-thinning agent, advantageously a polyolefin, preferably polyethylene. The total mass content of water-thinning agent, in particular of polyolefin (s), relative to the total weight of the mixture is preferably between 0, 05 and 5%, better between 2 and 4%.

By "rheofluidi fiant agent" is meant an agent which modifies the viscosity of the mixture in which it is incorporated when the shear rate increases, and in particular an agent which increases the viscosity for a low shear but allows the viscosity to decrease when the shear increases.

The mass content of emulsifier in the mixture relative to the total weight of the mixture can be between 0.05% and 5%, better still between 2 and 4%. The emulsifier facilitates the expansion by facilitating the fractionation.

The amount of gas incorporated by volume, relative to the volume of the mixture, preferably ranges from 1 to 60%, better still from 40 to 60%, the volume being measured at 20 ° C. and at atmospheric pressure (1013.25 hPa). The invention makes it possible to produce bubbles of relatively small size, in particular less than or equal to 500 microns, better at 150 microns, even better at 100 microns.

The mixture can be injected into the static mixer at a temperature between 1 and 5 ° C above the freezing point of the mixture.

The mixture can be injected into the static mixer at a temperature between 45 to 55 ° C.

The static mixer can comprise more than 10 mixer units, for example between 10 and 25, this number being adapted to the nature of the mixer and to the result to be achieved.

The foam can be injected as it is produced into molds to fill them. The injection can be carried out using at least one movable piston in a chamber. This allows precise dosing of the quantity dispensed.

The invention also relates to a process for manufacturing a candle, in which a wax foam is produced using the process according to the invention, as defined above. Candle molds can be filled with the resulting foam.

The invention also relates to an installation for producing wax foam, in particular for implementing the process as defined above, comprising:

- A heating tank of a mixture comprising at least one wax, at a temperature sufficient to liquefy the wax,

- at least one static mixer,

a system for injecting the molten mixture and a compound to be incorporated into the wax, preferably a gas, in particular air, into the static mixer and forming a wax foam,

- a distributor for distributing the wax foam thus obtained.

The dispenser may include at least one piston. The invention is not however limited to a particular technique for shaping the foam, and this can be carried out generally by pressing, extrusion, casting, filling or molding.

The installation can include several tanks connected to the same pump, the mixture being taken from a tank while another tank is used for its preparation. This allows operation in masked time.

The subject of the invention is also a candle, preferably obtained by implementing the method according to the invention, comprising a wax foam advantageously comprising a shear-thinning agent such as a polyolefin, for example between 2 and 4% by mass. , and preferably an emulsifier, for example between 2 and 4% by mass relative to the total weight of the mixture. The foam may have a pore size less than or equal to 500 microns, better still 150 or 100 microns. The pore size is the average size by volume, determined with a binocular microscope and by image analysis.

The invention applies to any form of candle, for example contained in a glass, a metal cup, to a molded candle, of classic or twisted shape, tinted or not in the mass.

The invention will be better understood on reading the detailed description which follows, of an example of non-limiting implementation of the invention, and on examining the appended drawing, in which:

FIG. 1 schematically and partially represents an installation for manufacturing wax foam according to the invention,

FIG. 2 partially and schematically represents an example of a static mixer that can be used,

FIG. 3 is an experimental map of flows as a function of the speed of the foam at the outlet and the pressure of the gas at the inlet, and

- Figure 4 shows the vacuum fraction obtained, for experimental results, as a function of the apparent viscosity of the mixture.

The installation 1 for manufacturing wax foam represented in FIG. 1 comprises several tanks 2, only one of which is shown, which make it possible to receive the starting mixture and to maintain it at the desired temperature, and a pump 3 which makes it possible to send the mixture contained in the tank 2 selected in a static mixer 4.

A set of valves 13 makes it possible to isolate the tanks 2 awaiting sampling. Thus, a mixture can be prepared in a tank 2 by the introduction of the ingredients and heating, while a ready-to-use mixture is taken from the corresponding tank 2 after opening the associated valve 13. The valves 13 can be manual valves or solenoid valves, which is advantageous to allow automated operation.

The installation 1 also includes a source 5 of pressurized gas, preferably compressed air, and a solenoid valve 6 which makes it possible to control the injection of this gas upstream of the static mixer 4 and downstream of the pump 3 A flow meter 7 provides information on the flow of mixture delivered to pump 3 and a pressure gauge 8 can be used to control the pressure of the gas injected.

After passing through the static mixer 4, the wax foam can fill the chamber 15 with a piston injector which is used to inject it into molds 16, known in themselves and only one of which has been shown in Figure 1.

A valve 17 makes it possible to isolate the chamber 15 once it has been filled with the wax foam to be injected into the candle molds, before the piston descends. The molds can be provided with wicks on standby.

The static mixer 4 comprises a plurality of mixer units 11.

An example of a static mixer which may be suitable is that sold by the company Sulzer Chemtech under the name SMX. The mixer unit model SMX10 is particularly suitable, but the invention is not limited to the use of such a model. The static mixer can include 25 units or less of SMX mixer, notably SMX10.

The mixer, for example of the SMX type, can comprise several mixer units 25 which are arranged one against the other within a tube in the direction of flow.

All the units 25 can be identical and one unit can be oriented 90 ° from the previous one around the longitudinal axis of the tube, as illustrated in FIG. 2.

Each unit 11 may include a plurality of parallel bars arranged in X, for example four parallel bars which intersect with four other bars parallel to each other and perpendicular to the first. The bars can be oriented at 45 ° from the longitudinal axis of the tube.

Application US 2012/0106290 A1 discloses other examples of static mixers which may be suitable.

The shear speed on passing through the static mixer can be between 1000 and 5000 s' ¹ .

The mixture present in tank 2 is suitable for making candles.

Mixed

The mixture contains at least one wax. The total amount of wax can represent at least 30% by mass of the mixture, better between 60 and 99% by mass.

By "wax" is meant any solid or semi-solid material at room temperature, insoluble in water, in particular non-food, of plant, mineral or animal origin.

The wax can be soluble in non-polar organic solvents.

The wax may comprise or be composed of at least one carbon-chain hydrocarbon with at least 18 carbon atoms, of a fatty acid ester of alcohol (s), of a "free" fatty acid or of 'a polyetheroxide, or a mixture thereof.

The melting point of the wax is preferably greater than or equal to 45 ° C.

Preferably, the mixture comprises at least one solid paraffin, the freezing temperature of which is preferably between 50 and 62 ° C. The mixture may contain oleic, linoleic, palmitic stearic acid.

The mixture can comprise a mono-, di- or triglyceride or a fatty acid, hydrogenated or not, fractionated or not.

The mixture may include an oil, in particular chosen from vegetable oils, in particular palm and rapeseed oils.

The mixture may comprise, in one example, between 50 and 90% by mass of a solid paraffin, between 5 and 50% by mass of partially fractionated palm oil.

Preferably, the mixture comprises a shear thinning agent such as a polyolefin, the shear thinning agent preferably having a freezing point of between 92 and 100 ° C. The total proportion of shear thinning agent, by mass relative to the total weight of the mixture, is preferably between 0 and 5%, better still between 2 and 4%.

Preferably also, the mixture comprises an emulsifier, preferably an emulsifier with thickening properties, such as a monoglyceride. The melting point of the emulsifier is preferably between 60 and 70 ° C. The total proportion of mass emulsifier relative to the total weight of the mixture is preferably between 0 and 5%, better still between 2 and 4%.

The emulsifier increases the crystallization temperature of the mixture by a few degrees, while the rheofluidifier induces an increase in viscosity without modifying the crystallization temperature.

The surface tension of the mixture can be between 19 and 35 mNm ¹ .

The temperature of the mixture pumped into the tank 2 is preferably between 40 and 50 ° C.

For a given mixing flow at the input of the static mixer, there is a maximum quantity of air that can be incorporated without causing the appearance of a pocket regime, this quantity maximizing the vacuum fraction and making it possible to obtain a density. minimum for wax foam. Preferably, the fraction of air which is incorporated is between 1 and 60% by volume, better between 40 and 60%.

For a given mixture, the expansion rate (i.e. the fraction of air) is controlled by the size of the static mixer, the mixing and gas flow rates, and the temperature.

FIG. 3 represents the results obtained for a mixture comprising 60% by mass of a solid paraffin, 30% by mass of partially fractionated palm oil, with 3% of polyolefin and 3% of emulsifier (by mass).

In this figure, each point represents the limit between dispersed regime and pulsed regime.

Below the limit given by the linear regression line, the gas pressure is too high compared to the total speed, and all the gas cannot be incorporated in the form of fine bubbles, which creates gas pockets. and very large bubbles in the foam. Above the limit, the gas is incorporated in a homogeneous and complete manner. The optimum is at the limit, which makes it possible to work at the highest gas pressure and therefore at the highest air incorporation rate, without the appearance of large air bubbles.

FIG. 4 represents the vacuum fraction obtained experimentally as a function of the apparent viscosity (in Pa.s). It can be seen that the more the apparent viscosity increases, the more the quantity of incorporable air increases. The presence of polyolefin makes it possible to work at a higher temperature while having a high viscosity, and thus to move away from the crystallization temperature of the mixture. The high viscosity allows stabilization of the foam after expansion. The use of a shear thinning agent is advantageous in that it makes it possible to limit the viscosity during the circulation of the fluid within the static mixer and a recovery of viscosity at the outlet of the mixer, which contributes to stabilize the foam. .

Although the compound incorporated into the wax mixture is air in the above example, other compounds are possible in addition and / or in place of air, for example water, which makes it possible to obtain a crackling effect, and / or a perfume. The wax foam according to the invention can also be used as a candle dipping and covering agent.

To do this, use candle foam still in a liquid state (above its freezing point), place it in a container and dip pre-formed candles in it.

Claims (15)

1. A method of manufacturing a wax foam, comprising the steps of: - inject a molten wax-based mixture and a compound to be incorporated into the mixture into at least one static mixer (4), - cool the foam obtained at the outlet of the static mixer. 2. Method according to claim 1, the compound to be incorporated being a gas, preferably air. 3. Method according to the preceding claim, the amount of gas incorporated by volume relative to the volume of the mixture ranging from 1 to 60%, better from 40 to 60%. 4. Method according to any one of claims 1 to 3, the mixture comprising at least one shear thinning agent, preferably a polyolefin. 5. Method according to claim 4, the total mass content of shear-thinning agent, in particular polyolefin (s), relative to the total weight of the mixture, being between 0.05 and 5%, better still between 2 and 4%. 6. Method according to any one of the preceding claims, the mixture comprising at least one emulsifier 7. The method of claim 6, the mass content of emulsifier in the mixture relative to the total weight of the mixture, being between 0.05% and 5%, better between 2 and 4%. 8. Method according to any one of the preceding claims, the mixture being injected into the static mixer at a temperature between 45 and 55 ° C. 9. Method according to any one of the preceding claims, the static mixer comprising at least 10 mixer units (11), preferably being of the S MX type. 10. Method according to any one of the preceding claims, the foam being injected as it is produced in molds (16) to fill them. 11. Method according to the preceding claim, the injection being carried out using at least one piston. ίο 12. A method of manufacturing a candle, in which the candle is produced with a wax foam produced using the method according to any one of the preceding claims. 13. Installation for the production of wax foam, in particular for implementing the process as defined in any one of claims 1 to 11 or claim 12, comprising: - A tank (2) for heating a mixture comprising at least one wax, at a temperature sufficient to liquefy the wax, preferably a plurality of tanks, the mixture preferably being pumped into a tank using a pump (3), 10 - at least one static mixer (4), a system for injecting the molten mixture and a gas, in particular air, into the static mixer and forming a wax foam, and - A distributor (15) for distributing the wax foam thus obtained. 14. Installation according to claim 13, the dispenser comprising at least 15 a piston.