FR2781235A1 - Particles for cleaning sand, especially in sandpits, comprise cleaning agent coated with water-insoluble material - Google Patents

Abstract

Particles for cleaning sand comprise a cleaning agent coated with a material that is insoluble in water but permits release of the cleaning agent in the presence of water. Independent claims are also included for the following: (a) self-cleaning sand comprising sand grains with a base coat of cleaning agent and a top coat of a material that is insoluble in water but permits release of the cleaning agent in the presence of water or a humid atmosphere; (b) production of the self-cleaning sand by fluidizing sand grains with air at 10 - 40 deg C, spraying the sand grains with a solution of the cleaning agent, allowing the grains to dry, spraying the grains with a polymer solution, and drying and recovering the coated grains.

Description

CLEANING PARTICLES, SELF-CLEANING SAND BASED

  SUCH PARTICLES, MANUFACTURING METHOD

  The invention relates to cleaning particles. It also relates to a self-cleaning sand based on its particles as well as its manufacturing process.

  In the following description, the particles of the invention relate more particularly to the cleaning of sand. Of course, the invention can be

applied to other areas.

  By "sand" is meant a granular material, that is to say a solid formed from discrete solid components in contact, the size of which advantageously lies between 60 micrometers and 2 millimeters. This granular material of the class of arenites is a product formed of loose rocks of detrital or clastic formation, that is to say coming from the slow disintegration of rocks under the action of eroding agents and mainly water and winds. This pulverulent medium can be formed either of grains of rounded shape (rolled sands of alluvial origin) or of irregular shape with sharp angles (crushed sands) .20 The present invention applies equally to sea sand (maritime sand), earth sand (quarry sand), river sand and any material

  granular, earth science materials or ceramics in particular, the size of which is between 60 micrometers and 2 millimeters, advantageously between 25,150 and 500 micrometers.

  The authorities are increasingly concerned with the problem of the hygiene of sandboxes, in particular sandboxes intended to be used for

  collectively, which led the Agence Française de Normalization to take a standard30 (NF-S-54-206).

  This standard is draconian insofar as apart from the requirements associated with the installation and design of sandboxes, it imposes the use of sand with specific characteristics (friability coefficient, particle size, cleanliness index). In addition, the sand should be subjected to regular examinations, both parasitological and bacteriological. In addition, it is

  indicated that it must be renewed at least once a year.

  Even if this standard aims to be made more flexible, it still remains very demanding and involves significant user costs.

  Independently of the collective sandboxes, we note that many households, in particular people living in individual houses, are equipped with

  their own sandbox to allow their children to play in the garden.

  However, no hygiene standard is imposed on the sale of sand intended to fill the sandbox. Sand is therefore available from material sellers, without any special precautions. During use, the child can be easily contaminated by dirty sand, subjected to the weather, and which the animals can otherwise soil. In addition, the development of pathogenic germs is observed on the surface of the sand. In this case, the hygiene measures are very limited and are limited, most of the time, to the pure and simple change of the sand. It is then necessary to obtain sand refills, about 50

  kilograms and refill the sandbox.

  To overcome these hygiene problems, the document FR- has proposed

  A-2 674 274, a device for protecting the sandbox from animal and atmospheric stains in the form of a metal frame. It is obvious that this

  type of structure is difficult to adapt in the context of small individual sandboxes. In addition, despite the presence of protection, the sand gets dirty as it is used.

  The problem which the invention proposes to solve is to define a means making it possible to have constantly clean sand, in particular with a view to

  its use in children's sandboxes.

  Another problem which the invention proposes to solve is to develop a sand the frequency of renewal of which can be reduced.

  To do this, the invention provides a cleaning particle intended for washing sand, characterized in that it comprises at least one cleaning agent coated with a layer which is not soluble in water capable, however, of allowing the release of the cleaning agent in the presence of water. By "water" is also meant

  humidity or humid atmosphere.

  In other words, the invention resides in that cleaning particles comprising a coated cleaning agent are added to the sand so that the particle gradually releases the cleaning agent on contact with water or

  humidity and thus allows the washing of sand by contact.

  In practice, the user will therefore be able to recharge their particle sandbox

  cleaning, periodically, to keep the sand constantly clean and thus have a self-cleaning sand.

  However, and according to an advantageous form of the invention, the cleaning particle also comprises a grain of sand.

  In this case, there will be a self-cleaning sand consisting of a multitude of grains of sand each covered with at least two distinct layers, namely respectively from the inside to the outside: has a first layer comprising a cleaning agent ; To a second layer not soluble in water capable, however, of allowing the contents of the first layer to be released in the presence of water or moisture.

  In the following description and in the claims, by << agent

  cleanser >>, we designate indifferently soaps, wetting agents, detergents, disinfectants, antiseptics, taken alone or as a mixture.

  According to an advantageous embodiment of the invention, the cleaning agent is solid. Indeed, the cleaning agent dissolves in contact with water from the external environment via the non-soluble layer in the case of particles, via the second layer in the case of coated sand grains, the cleaning solution then obtained

  then diffusing through the same channels to the outside environment.

  According to another embodiment, the cleaning agent is originally in liquid form and then is made pasty by the addition of agents which consequently increase their viscosity (colloidal silica and the like). In practice, the child playing in the sandbox handles the sand in the presence of water, whether to make pies, holes or other shapes and thereby causes a "lubricated" friction of the grains between them. This friction or rolling or crushing in an environmental medium allows on the one hand a better release of the cleaning agent via the first layer, and on the other hand

  on the other hand, a distribution on the surface of the grains of the aqueous solution of cleaning agent, making it possible to obtain a constantly clean sand.

  Furthermore, the cleaning agent which must not intrinsically modify the capillary forces ensuring the compaction of the grains, must fulfill two objectives, namely :. have hypoallergenic characteristics vis-à-vis the skin and mucous membranes of the child,

  can be accidentally ingested without any consequences.

  To solve this problem, the cleaning agent is advantageously chosen from the group comprising soaps and amphiphilic products usable in the cosmetic and / or food industry.

  Advantageously, the cleaning agent is a fatty acid ester, an amide, a fatty alcohol such as stearate, palmitate, laurate .....

  Likewise and as already said, in order to avoid any release of the cleaning agent through the non-soluble coating layer of the first layer through the surface layer in the absence of any abrasive friction of the cleaning particles between them or of the grains of sand between them, the cleaning agent is of a solid or liquid nature made pasty and dissolves on contact with the water that the child uses to make the sand pies. According to a first embodiment of the invention , the cleaning agent is a soap, glycerin or not, in solid or granular form or under

glitter shape.

  According to a second embodiment of the invention, the cleaning agent is an agent with detergent properties having an HLB (balance

  hydrophilic / lipophilic) in the Griffin scale greater than or equal to 14.

  According to a third embodiment, the cleaning agent is a wetting agent having an HLB of between 6 and 12. According to another characteristic of the invention, in order to allow the contact of water with the release of the cleaning agent, then its distribution around each of the

  coated grains, the water-insoluble layer has a plurality of cracks or microchannels connecting the outer surface of the layer to its inner surface.

  In other words, the release of the cleaning agent taking place by forced passage, is linked to the quality of the porosity or of the microcracking of the

layer not soluble in water.

  According to a preferred embodiment, said layer comprises a polymer tolerated in the food industry chosen from the group of non-water-soluble polymers. However, these polymers can be hydrophilic.

  It can also be carried out using a latex or a mixture of polymers or even copolymers, one of the constituents of which is water-soluble.

  Furthermore, the proportions (by mass or by volume) of the material of this layer will be selected by a person skilled in the art so that the deposit covers the grain of sand coated with the cleaning agent, leaving residual

  micro cracks or microchannels where the exchange reactions will take place.

  Advantageously, the polymer chosen is an acrylic polymer.

  In practice, the mass of polymer in solution represents between 5 and 15% of the total mass of the sand, advantageously 10%. For a polymer mass of less than 5%, the grain recovery rate is too low. On the other hand, for a polymer mass greater than 15%, the grain recovery rate is excessive and creates a layer that is too thick to release the cleaning product.

  One can also envisage other embodiments of the sand of the invention.

  Thus, in order to obtain a self-cleaning sand presenting a pleasant odor, the cleaning particles comprising or not grains of sand may have

  an additional layer capable of diffusing a perfume during the abrasive friction of the grains between them.

  This perfume can also be incorporated into a porous material itself encapsulated or be contained in the soap which will thus be perfumed.

  Similarly, in order to detect any contamination in the sand (animal urine or the like), the cleaning particles may also have a layer comprising

a pH dependent reagent.

  Likewise, an animal repellant can be incorporated into the self-cleaning sand.

  To visually distinguish the self-cleaning sand of the invention from a conventional sand, the grains of sand may be colored. Of course, all

colors may be suitable.

  The invention also relates to the process for making sand

self-cleaning.

  According to this process: A the grains of sand are suspended in a fluidized air bed at a temperature between 10 and 40 ° C., then a first solution comprising a cleaning agent is sprayed on these grains of sand in suspension. to constitute a first layer, the grains thus treated are left to dry, * a second solution of polymer is then sprayed on these grains, in order to constitute a second layer, finally, it is dried and then the grains of coated sand thus obtained are recovered. These various operations are repeated when it is desired to produce intermediate layers in order to release a perfume, to insert a pH-dependent reagent, or a soil-detection product. Of course, the grain air flow rate, the spray rates and the spray pressures of the solutions constituting the

  first and second layers depend on the volume of sand to be treated and will be chosen accordingly.

  Advantageously, the sand is sieved beforehand, washed and dried before being placed in homogeneous suspension, in order to remove harmful impurities

  such as particles of the lutite or rudite class, fibrous materials.

  Similarly, when the cleaning agent is in solid form, it is dissolved beforehand in a solvent, then sprayed onto the grains, the solvent

  then being evaporated during the drying of the grains, before spraying of the polymer in solution in a solvent medium of the second layer constituting the envelope.

  The manner in which the invention is carried out and the advantages which result therefrom will emerge clearly from the example of embodiment below with the support of the appended figures.

  Figure 1 is a photograph of a grain of sand in the raw state before treatment described in the invention.

  Figure 2 is a photograph of a grain of self-cleaning sand treated

according to the invention.

  The examples below were carried out on a laboratory scale.

  In the two examples of preparation presented, the following operations are carried out beforehand:

  500 g of sand between 250 and 800 micrometers are sieved.

  The sand thus sieved is then incorporated into a machine known as a "Spray coating" (for example of the Glatt Pharma, Niro, etc. type) or a turbojet of the type

  Kugel Coater of H ttlin, then the sieved sand is suspended at a fluidization air temperature of 27 C and at an air flow rate between 80 m3 / hour up to 130m3 / hour.

Example 1

  The composition constituting the first layer is prepared from a solution of 5 to 10 g of flake soap in 500 cm3 of water.

  Filtering of this solution is then carried out to remove solid residues.

  The filtered solution is then sprayed onto the sand in suspension at a

  pressure of 1.5 - 2 bar and a spray rate of 8 ml / min at 30 C.

  The grains of sand coated with the first layer are then allowed to cool for a few minutes.

  The second layer consisting of 150 g of EUDRAGIT is then prepared. L30D-55 marketed by ROHM and HASS (approximately 42 g of solid compound). EUDAGIT is then sprayed onto the grains of sand beforehand

  treated at a temperature of 35 C under a pressure of 2 bars, a spray rate of 5 ml / min.

  After treatment, grains of sand are obtained, the surface coating of which is cracked as shown in FIG. 2.

Example 2

  The composition constituting the first layer is prepared by dissolving 25 g of MONTANOX 65 sold by SEPPIC in 225 g of absolute ethanol. The solution thus produced is then sprayed onto the suspended sand at a pressure of 2 bars and a spray rate of 3 ml / min, then 5 ml / min, at 37 C.

  The grains of sand coated with the first layer are then allowed to cool for a few minutes.

  The operation is then carried out as described in Example 1 to produce the second layer.

  The surface layer has the same texture as that presented on the

figure 2.

  Comparative tests were then carried out between the natural sand, the sea sand and the self-cleaning sand of the invention by calculating the following values a) The slope angle (acT) The slope angle, designated aT represents the angle of the cone measured between the horizontal and one side thereof, the cone being formed during the flow

  controlled with a quantity of sand previously sieved with a 24 mesh sieve.

  b) The angle of fall (oaQ The angle of fall, designated acC is the angle previously described determined after landslide caused by the fall of a weight from a defined height, in a

area next to the heap of sand.

  c) The difference angle (aD_ The difference angle, designated by aD corresponds to the difference between the slope angle (aT) and the fall angle (aC): D = uT - aC d) L ' tip angle (aS_ The tip angle cxS corresponds to the average between the angle of the residual cone obtained after insertion and removal of a tip of width defined in

  a bed of sand and this same angle, after unitary fall of a weight of defined mass5 positioned at the edge of the spatula.

  e) Bulk density (A) It is obtained by weighing the mass of the pulverulent product in a confined volume and of known capacity. We fill the reference volume by making

  flow the sand by vibration through a 24 mesh screen in a time between 20 and 30 seconds.

  f) Bulk density (P) It is obtained by weighing, in a confined volume and of known capacity, the mass of the pulverulent product subjected to a compaction caused by the action of an eccentric rotating at a frequency of 50 periods per minute

  (50 Hertz) for a defined time (216 seconds).

  g) The compressibility (C) It corresponds to the following formula: C = P-A x100 P with: P = compacted bulk density

A = bulk density not packed.

  h The dispersibility (D) The dispersibility (D), also expressed as a percentage, is obtained by

  measuring the residual mass retained by dropping from a defined height a known quantity (m = 10 g) of product through a calibrated cylindrical tube.

  This quantity is defined by the formula: D = (10 - P) 10.

  Il i) Coefficient of friction (F) The coefficient of friction represents the quantity associated with the tangent (tg) of the minimum angle (w) that an inclined plane takes to ensure a sliding

beginner either: F = tg w.

  Table I groups together the comparative quantities obtained.

TABLE I

  Quarry sand Sea sand Sand mm <diameter> 800mm) 200mm <diameter> self-cleaning 600mm)

35 32

CCC (0) 18 17 17

  ccD (0) 17 18 15 acS (') 30 31 29 A (g / cm3) 1.63 1.7 1.46 P (g / cm3) 1.66 1.72 1.46

C (%) 1.8 1.2 0

D (%) 45 45 45

F 0.48 0.65 0.72

  The angular values correspond to the average over five experimental values.

  It appears that the flow characteristics and the few associated physical data are almost identical between the samples of natural sand and those of self-cleaning sand with the exception of the coefficient of friction which appears

  as the only truly discriminatory parameter.

  We then composed the foaming power of the self-cleaning sand of

  the invention and that of natural sand.

  This power was defined by analyzing the amount of foam obtained after immersing in 200 cm3 of water, 150 g of self-cleaning sand or sand

  natural, for 2 hours with magnetic stirring at the speed of 750 5 revolutions / minute.

  It appeared that: - immediately after immersion, the liquid supernatant above the self-cleaning sand is cleaner, that is to say that it contains less debris than natural sand; - after 2 hours of immersion, the foaming power is visible but the quantity of foam is low, or even almost non-existent; - the renewal of the water above the two categories of sand does not modify, after 1 additional hour of agitation, the low power

foaming found.

  The advantages of the invention appear clearly from the description.

  Note in particular the ease of use and the reliability of the sand

self-cleaning of the invention.

  In fact, the user can have constantly clean sand: * either by using "conventional" sand to which he periodically adds cleaning particles,

  * or by using sand directly coated with cleaning particles.

  Indeed, this self-cleaning sand by its structure allows to have a clean sand thanks to the release of a cleaning agent on the surface of the grains, thus avoiding any contamination between the sandbox and the child. In addition, the sand can only be partially renewed by remixing the sand of the invention with used sand, which will also benefit from the effects of the cleaning agent by abrasion of the grains therebetween. There is thus a reduction in the cost of use.

Claims (13)

  1 / cleaning particle intended for washing the sand, characterized in that it comprises at least one cleaning agent coated with a layer which is not soluble in water capable, however, of allowing the release of the cleaning agent in the presence of water .   2 / Particle according to claim 1, characterized in that it further comprises a grain of sand coated with said cleaning agent.   3 / Particle according to one of claims 1 to 2, characterized in that the cleaning agent is chosen from the group comprising soaps, products   amphiphiles, wetting agents, detergents, disinfectants, antiseptics, taken alone or as a mixture.   4 / Particle according to claim 3, characterized in that the cleaning agent is a wetting agent having an HLB of between 6 and 12.   / Particle according to claim 3, characterized in that the cleaning agent   is an agent with detergent properties having an HLB (hydrophilic / lipophilic balance) greater than or equal to 14.   6 / Particle according to one of the preceding claims, characterized in that said water-insoluble layer has a plurality of cracks or   microchannels connecting its external surface to its internal surface.   7 / Particle according to claim 6, characterized in that said layer comprises at least one non-water-soluble acrylic polymer.   8 / Self-cleaning sand characterized in that it consists of a mixture of grains of sand and cleaning particles according to one of claims 1 to 7.   9 / Self-cleaning sand characterized in that it consists of a multitude of grains of sand each covered with at least two distinct layers, namely respectively from the inside to the outside: To a first layer comprising a cleaning agent ; a second water-insoluble layer capable, however, of allowing the contents of the first layer to be released in the presence of water, or humid atmosphere.   10 / Self-cleaning sand according to claim 9, characterized in that said second layer comprises at least one non-water-soluble acrylic polymer, of which   the mass represents between 5 and 15% of the total weight of the sand.   11 / Self-cleaning sand according to one of claims 9 to 10, characterized in   what the grains of sand are capable of diffusing a perfume, a repellent   12 / Self-cleaning sand according to one of claims 9 or 11, characterized in that the grains of sand also have an additional layer   including a pH-dependent reagent. 15   13 / Self-cleaning sand according to one of claims 9 to 12, characterized in that the grains of sand also have an additional layer   comprising a pH dependent reagent.   14 / A method for manufacturing self-cleaning sand according to one of claims 9 to 13, characterized in that: the grains of sand are suspended in a fluidized air bed at a temperature between 10 and 40 C, then sprayed on these grains of suspended sand a first solution comprising a cleaning agent in order to constitute a first layer, A the grains thus treated are allowed to dry, * a second solution of polymer is then sprayed on these grains, in order to constitute a second layer, finally, it is dried and then the grains of coated sand thus obtained are recovered.