FR2588263A1 - Process for the manufacture of particles of semicrystalline polymers of controlled particle size, products obtained and application of these products - Google Patents

Abstract

Process for the manufacture of particles of semicrystalline polymers, characterised in that it consists: - first of all, in dissolving this polymer in a solvent, with heating and with stirring until a solution in a homogeneous liquid phase is obtained; - then, in cooling in order to recrystallise the polymer without the appearance of a liquid-liquid phase separation; - and, finally, in removing the solvent. Envisaged application: ion exchange resins, particles for fluidisation, aqueous dispersions, film resins supporting catalysts or chemical reactants.

Description

PROCESS FOR THE MANUFACTURE OF POLYMER PARTICLES
SEMI-CRYSTALLINE CONTROLLED GRANULOMETRY, PRODUCTS
OBTAINED AND APPLICATION OF THESE PRODUCTS.

 The invention relates to a new process for the production of semi-crystalline polymer particles of controlled particle size. It also relates to the particles thus obtained; it finally relates to applications of these particles.

 There are different processes for obtaining semi-crystalline polymers and more particularly polypropylenes in powder form from the polymer obtained in the polymerization in the form of grains or from polymers in the form of granules obtained by extrusion.

 Cryogenic grinding is one of these processes, but it leads on the one hand to polymer particles with a very wide size distribution, and other Dart to various shapes, but not spherical, which can be a disadvantage for many applications.

 Another method is to emulsify the semi-crystalline polymer in water. In US Pat. No. 3,746,681, a method adapted to polyethylene is described which uses generally high temperatures, equal to or greater than 200 ° C., but also at high pressures greater than 10 bar and high agitation of the order of 8000 to 10 000 rpm related to the high viscosity of the polymer in the molten state.

The particles made in this process do not have a narrow size distribution and range from 0 microns to a few microns. In addition, these tough emulsification conditions (high temperature and high Fress) do not allow Fas to form into particle form with a narrow and controlled granulometry grafted semicrystalline polymers comprising chemical functions sensitive to hydrolysis reactions, such as for example oxirane functions or esters.

 French Patent FR-A-2,448,514 describes the coemulsification of a mixture of isotactic polypropylene and of amorphous polypropylene functionalized with acidic groups or acid anhydrides to make them self-emulsifiable, by adding a base such as that for example potash. The emulsification in water is performed at more than 1700C, so at a pressure equal to or greater than 7 bar. Under these conditions, it is not possible to emulsify an ungrafted polypropylene or a polymer having functions sensitive to hydrolysis reactions, such as for example oxirane groups or esters.

A third method consists in dissolving the polymer in a compatible liquid until a homogeneous solution is obtained, then cooling the solution until a liquid / liquid phase separation is obtained before the solidification process, and finally extracting the liquid. compatible with a solvent. The European patent
EP-A-0044052 discloses a process of the type in question for preparing porous polypropylene particles from a solution in an ester of pentaerithrol and a fatty acid. The fact of obtaining particles with a high porosity is a drawback for the main areas of use envisaged, namely materials for ion exchange resins in general and more particularly ion exchange resins with rapid exchange kinetics or realization Moreover, given the size of the particles obtained (50 to 700 microns), these particles are not dispersed.

water phase for use as an emulsion.

 In FR-A-2 362 890 it has been proposed to replace this pentaerythrol ester with a compatible liquid. A microporous polymer solid is thus obtained characterized by a three-dimensional void cellular microstructure, that is to say a series of closed cells, of substantially spherical shape, and of pores which connect neighboring cells. This method therefore does not make it possible to obtain particles.

 In short, to date, it is not known to achieve economically nonporous particles controlled particle size.

 The invention overcomes these disadvantages. It aims a process for the preparation of semi-crystalline polyolefins in the form of powder, in particular spherical particles, with a controlled particle size, these particles being perfectly adapted to the various applications envisaged.

 Another object of the invention is also to produce aqueous suspensions of fine particles, especially in the spherical form.

 Another object of the invention is to produce film resins based on functionalized polypropylene.

 Other objects of the invention will appear better in the following description.

The process of the invention for the manufacture of semi-crystalline polymer particles, in particular
polyolefins, is characterized in that it consists
firstly, to dissolve this polymer under heat and with stirring, in a solvent until a homogeneous liquid solution is obtained,
then, to cool to recrystallize the polymer, without showing a liquid / liquid phase separation,
and finally, to eliminate the solvent.

 In other words, the invention relates to a process for preparing semi-crystalline polymer particles, by recrystallization of this polymer from a homogeneous solution thereof in a good solvent and therefore without liquid phase separation. -liquid before the solidification process.

Advantageously, in practice
the semi-crystalline polymer is isotactic polypropylene, and the solvent is chosen from the group
consisting of xylene, orthodichlorobenzene, decahydronophthalene, and the decane as already said with stirring and hot
- This solution is cooled slowly in pouring, the dissolution vessel, soit this solution in a container at room temperature, or even at a lower temperature
the water is added, with stirring, to the homogeneous hot polymer solution at a temperature close to that of the hot solution, until a water-in-oil emulsion is obtained before recrystallizing the polymer during cooling.
in a variant, hot water is continued to be added to the water-in-oil emulsion until the phase inversion (oil in water) is obtained, then this emulsion is cooled; this cooling can be done essentially in two ways
quickly (on the order of a few
condes, or even minutes) and we obtain
micron-sized particles, sometimes even
less than a micron,
. be slower (of the order of the hour)
and you get bigger particles
(more than five microns)
- the added hot water contains an emulsifying agent
the solvents are removed in known manner either by extraction, washing and drying, or possibly filtering.

In an advantageous variant, the method of the invention may be associated with a functionalization process of the particles of appropriate particle size. This functionalization, which consists in grafting chemical functions onto the polymer backbone, may be carried out in various ways, and in particular by the technique described by the Applicant in the patent FR-A-2,517,682 (known
US-A-4,443,584).

 In a first embodiment, this embodiment can be performed on the starting polymer itself.

 In a second embodiment, it may be performed on the particles obtained according to the method.

 Advantageously, this functionalization can also be carried out in the polymer solution itself before cooling the composition.

 The invention also relates to applications of the polymer particles prepared according to the invention, as ion exchange resins or in the impregnation of fibers for the manufacture of composite materials or in the form of aqueous dispersions.

 The manner in which the invention can be realized and the advantages which result therefrom will emerge more clearly from the following exemplary embodiments given as an indication and not a limitation.

 If in these examples is essentially using isotactic polypropylene, it is understood that the invention is not limited to this type of polymer, since it includes all semi-crystalline polymers, including other polyolefins, such as for example polyethylene, polybutene.

Unless otherwise indicated, in these examples, the polypropylene used is a polypropylene marketed by Naphtachimie under the trademark NAPRYL 61200 ", with a molecular weight of Mw = 330 000 and a number-average molecular weight Mn = 70 000. For each type of particle population, the diameters are determined by a scanning electron microscopy examination which makes it possible to define a number average diameter Dn which is an arithmetic mean of the diameters, and a mean diameter by weight Dp given by the

<tb> relation
<tb><SEP> i <SEP> i <SEP> = <SEP> n
<tb><SEP> mi <SEP> | <SEP> E <SEP> mi <SEP> Di3
<tb><SEP> Dp <SEP> = <SEP> i
<tb><SEP> 1 <SEP> I
<tb><SEP> mi
<tb><SEP> i = o
<Tb>
mi being the mass of the particle of diameter Di and n
the number of particles measured.

~~ report of these two quantities Dp / Dn defines the
polydispersity of the particle sizes obtained.

The dissolution of the polymer is carried out in a jacketed reactor allowing the circulation of a thermostatically controlled fluid. This reactor is surmounted by a
ascending refrigerant to reach the
boiling temperature of the solvent used. This reactor
is also provided with a stirring system with a
blade in the form of anchor, to agitate the composition.

After recrystallization, the polymer is filtered on a sintered glass and then washed with acetone until
completely eliminate the residual solvent retained in
the particles of the polymer.

 Likewise, unless otherwise indicated, in the Tables, the polymer concentration C is given in grams of polymer per liter of solvent and the diameters Dn and Dp are given in microns.

Example i
Using the apparatus described above, varying amounts of NAPRYL polypropylene in 250 ml of ortho-dichlorobenzene were dissolved under stirring at 1500 ° C. The solution is cooled by transfer into a one-liter beaker. We go from 1500C to 50 C in about 45 minutes. The results obtained are collated in Table I below.

TABLE I

<tb> C <SEP> Dn <SEP> Dp <SEP> Dp / Dn
<tb><SEP> 50 <SEP> 1.7 <SEP> 2 <SEP> 1.18
<tb><SEP> 100 <SEP> 4.9 <SEP> 7 <SEP> 1.43
<tb><SEP> 267 <SEP> 61 <SEP> 81 <SEP> 1.40
<Tb>
It is observed that the particle size is a function of the concentration. For concentrations equal to or greater than 100, the particles obtained are not spherical, but of prismatic appearance.

Example 2
Example 1 is repeated but cooling is carried out more slowly in the reactor itself. The time required to go from 1500C to 50 C is four hours. The results obtained are collated in Table II below.

TABLE II

<tb><SEP> C <SEP> Dn <SEP> Dp <SEP> Dp / Dn
<tb> 270 <SEP> 116 <SEP> 147 <SEP> 1.26
<tb> 400 <SEP> 119 <SEP> 153 <SEP> 1.28
<Tb>
Thus, the concentration range for which particle size varies with concentration is more restricted for slow cooling than for rapid cooling.

Example 3
Example 1 is repeated, but the solvent is changed.

 The results obtained are collated in Table III below.

TABLE III

Solvent <SEP> Temperature <SEP> C <SEP> Dn <SEP> Dp <SEP> Dp / Dn
<tb> boiling
<tb> (C)
<tb> Xylene <SEP> 140 <SEP> 100 <SEP> 92.2 <SEP> 93.5 <SEP> 1.01
<tb> 270 <SEP> 37.3 <SEP> 39.7 <SEP> 1.06
<tb> 400 <SEP> 18.9 <SEP> 21.1 <SEP> 1.11
<tb> Decane <SEP> 173 <SEP> 150 <SEP> 147.2 <SEP> 171 <SEP> 1.16
<tb> 270 <SEP> 135.7 <SEP> 150.7 <SEP> 1.10
<tb> 400 <SEP> 251 <SEP> 278 <SEP> 1.10
<tb> Decahydronaphthalene <SEP> 190 <SEP> 270 <SEP> 67.9 <SEP> 96.8 <SEP> 1.42
<tb> 350 <SEP> 78.06 <SEP> 95.4 <SEP> 1.22
<tb> 600 <SEP> 151.2 <SEP> 188.5 <SEP> 1.24
<Tb>
Examination of the electron micrographs of the particles thus produced and whatever the solvent, shows that they are essentially spherical for polymer concentrations greater than or equal to 100 g / l and that their polydispersity in size varies with the nature of the solvent. solvent.

 In xylene, for concentrations of 100 g / l these particles are perfectly spherical and monodisperse in size. When the concentration changes, the morphological characteristics remain unchanged.

 In addition, the particle size developed in xylene by recrystallization decreases as the concentration of the polymer increases.

Example 4
Example 1 is repeated, but the temperature of the polypropylene solution from which the rapid transfer for cooling is carried out is varied.

 The solvent is also replaced by decane and the solution is dissolved at 158 ° C. with stirring.

 The solution obtained is then cooled slowly with stirring in the reactor itself to an initial temperature Ti before cooling. Once this temperature Ti is reached, the contents of the reactor are transferred to a beaker.

 The results obtained are collated in Table IV.

TABLE IV

<tb> Ti <SEP>("C)<SEP> Dn <SEP> Dp <SEP> Dp / Dn <SEP>
<tb> 158 <SEP> 86 <SEP> 130 <SEP> 1.5
<tb> 148 <SEP> 45 <SEP> 56 <SEP> 1.24
<tb> 132 <SEP> 15 <SEP> 20 <SEP> 1.33
<tb> 125 <SEP> 13 <SEP> 15 <SEP> 1.15
<tb> 110 <SEP> 13 <SEP> 14 <SEP> 1,07 <SEP>
<Tb>
The electron micrographs of the particles thus produced show that they are close to a sphere whatever the temperature Ti but that their size is highly dependent on this temperature. Finally, the lower the initial temperature of the solution, the more limited the dispersion. Thus, at 110 C, the particles are almost monodisperse.

Example 5
Example 4 is repeated, but using functionalized polypropylene having glycidyl methacrylate grafts (oxirane function). The concentration of the polymer is set at 50 g / l and the volume of decane at three liters. The results obtained are shown in Table V.

TABLE V

<SEP> Ratio of <SEP> Methacrylate <SEP> Mass <SEP> Molecular <SEP><SEP> Temperature <SEP><SEP> Dn <SEP> Dp <SEP> Dp / Dn
of <SEP> glycidyl <SEP> grafted <SEP> of <SEP> polymer <SEP> grafted <SEP> solution <SEP> before
<tb> cooling
<tb> (%) <SEP> (Mw <SEP> x <SEP> 10-3) <SEP> (C)
<tb> 10 <SEP> 124 <SEP> 132 <SEP> 18.7 <SEP> 22.4 <SEP> 1.19
<tb> 4 <SEP> 110 <SEP> 132 <SEP> 10.3 <SEP> 11.9 <SEP> 1.15
<tb> 0 <SEP> 131 <SEP> 110 <SEP> 1.3 <SEP> 1.5 <SEP> 1.15
<tb> 6 <SEP> 110 <SEP> 110 <SEP> 1.4 <SEP> 1.6 <SEP> 1.14
<tb> 10 <SEP> 124 <SEP> 110 <SEP> 2.5 <SEP> 3.0 <SEP> 1.20
<Tb>
Examination of the electron micrographs shows that the grafted polypropylene particles obtained for an initial temperature before cooling of 1500C have a roughly spherical shape with sizes between twenty and ten microns. On the other hand, the particles elaborated by recrystallization from a solution brought back to 110 C before rapid cooling, are not spherical but parallelepipedic or cubic with sizes comprised between 1.5 and 2.5 microns, contrary to the teachings of the previous example.

 Finally, for grafting levels less than or equal to 10%, it is observed that the presence of glycidyl methacrylate grafts on the polypropylene backbone does not alter the process of formation of the particles produced by recrystallization in a good solvent and does not modify sensibly the particle size of these particles.

Example 6
In a solution of 200 ml of decahydronaphthalene, at 190 ° C. with stirring, twenty grams of polypropylene and 1.5 g of polystyrene of molecular weight Mw 235,000 are dissolved. Once the dissolution is obtained at 190 ° C., stirring is stopped and the solution is slowly cooled in the reactor itself. The polystyrene is then extracted with toluene.

 The results obtained are collated in Table VI below.

TABLE VI

- <SEP> - <SEP> - <SEP>
<tb><SEP> Concentration <SEP> Dn <SEP> Dp
<tb> polypropylene <SEP> polystyrene
<tb><SEP> 100 <SEP> 7-, 5 <SEP> 18.9 <SEP> 19.9
<tb><SEP> 150 <SEP> 12.5 <SEP> 35.7 <SEP> 46.6 <SEP> 1.3 <SEP><SEP> 1 <SEP>
<tb><SEP> 200 <SEP> 15 <SEP> 106.5 <SEP> 131 <SEP> 1,2
<Tb>
Examination of electron microscopy photographs of the polypropylene particles obtained after extraction of polystyrene with toluene shows that these partiles are spherical irrespective of the concentration of the two starting polymers and have an alveolar morphology.

Example 7
Example 1 is repeated. Once the isotactic polypropylene has been dissolved while stirring, the temperature of the solution is allowed to drop to 1000 ° C. At this time, boiling water containing a non-ionic emulsifying agent, such as polyoxyethylenepolyoxypropylene marketed by BASF under the brand, is slowly introduced into the solution.
PE 6,800 (POX). This boiling water is introduced by means of a peristatic pump into the solution maintained with vigorous stirring. It is important that the concentration of the polymer solution does not cause recrystallization of the polymer solution in the temperature range of 90 ° to 100 ° C. In practice, it is sufficient that this concentration remains below 200 g / l.

 An emulsion of water is thus produced in the polymer solution which remains in a continuous medium. Then from a certain volume of water added, and depending on the agitation, the appearance of the phase inversion phenomenon is observed, the water becoming the continuous medium and the polymer solution passing in the form of droplet dispersed in the aqueous phase. Micron-sized particles are thus obtained.

 On the other hand, if this phase inversion is not achieved, the cooling of the water emulsion in polymer solution causes the formation of particles whose dimensions can vary from micron to about ten microns and whose shape is generally not spherical, but of variable shapes depending on the cooling rate.

 In practice, the residual solvent contained in the particles is removed by washing with acetone and then rinsing with water.

Example 8
Example 7 is repeated on the one hand by replacing the isotactic polypropylene with isotactic polypropylene grafted with glycidyl methacrylate and, on the other hand, by replacing the emulsifying agent with a quaternary ammonium salt marketed by Rhône.
Poulenc under the trademark "CEQUARTYL 12" to avoid hydrolysis of oxirane and ester functions.

 The cooling is carried out by pouring the hot emulsion abruptly into an equal volume of water or acetone at 15 ° C. Under these conditions, the cooling of 100 ° C. at ambient temperature only takes place in a few seconds.

Table VII summarizes the results obtained. TABLE VII

Test <SEP> Viscosity <SEP> Rate <SEP> of <SEP> Solvent <SEP> C <SEP> V <SEP> Water / <SEP> Type <SEP> of <SEP> Size
<tb> n <SEP> of <SEP> grafting <SEP> Vsolvent <SEP> cooling <SEP> particles
<tb> Polymer <SEP> in <SEP> Volume <SEP> Degradation <SEP> Dn
<tb> grafted
<tb> (Pa / s) <SEP>%
<tb> A <SEP> 1 <SEP> 200 <SEP> 11.5 <SEP> Orthodics <SEP> 100 <SEP> 3 <SEP> Water <SEP> 1 <SEP> to <SEP> 3
<tb> chloro ~
<tb> benzene
<tb><SEP> B <SEP> 70 <SEP> 9 <SEP> same <SEP> 130 <SEP> 4 <SEP> acetone <SEP> 5
<tb> C <SEP> 10 <SEP> 1.5 <SEP> Decane <SEP> 130 <SEP> 4 <SEP> Water <SEP> 1 <SEP> to <SEP> 5
<tb> D <SEP> 700 <SEP> 5.6 <SEP> Decahydro- <SEP> 130 <SEP> 4 <SEP> Water <SEP> 2 <SEP> to <SEP> 4
<tb> naphthalene
<Tb>
Example 9
Example 8 is repeated, but increasing the amount of hot water added.

 The phase inversion appears for water / solvent ratios greater than three. But this inversion is not spontaneous. It must be provoked either by the addition of a large volume of water, or by a sudden change in stirring speed, or finally by adding a small amount of an aqueous concentrated solution of the emulsifier to the emulsion.

 Phase inversion is observed by a sudden change in viscosity which then changes the stirring conditions.

 When the phase inversion is performed, the rapid cooling is obtained by a direct transfer of the reactor contents in a volume of water equivalent at room temperature or in acetone maintained. at OOC.

 After removal of the solvent, the particles obtained are spherical and very fine and have a particle size of the order of one micron with a narrow polydispersity. Thus, they are easily redispersible in water in the presence of an emulsifying agent.

 Thus, Examples 7,8 and 9 show that it is possible to emulsify isotactic polypropylene, grafted or not, under mild conditions, by means of a solution of this polymer in solvents such as orthodichlorobenzene , decane or decahydronophthalene, whereas up to now, this polymer was deemed particularly difficult to economically put in the form of emulsion. Thus, this process is particularly well suited to the production of chemically modified polypropylene particles, in particular functionalized particles comprising oxirane or ester functions, provided in particular that a cationic emulsifier such as a quaternary ammonium or chloromethylstyrene functions can be used. .

 In addition, this process which is flexible makes it possible to obtain fine isotactic polypropylene particles whose size is between one and twenty microns with an emulsion without phase inversion and of the order of one micron, or even sub-micron with inversion. phase.

Example 10
By implementing the grafting method described by the Applicant in the patent application FR-A-2,517,682 referred to in the preamble, hydroperoxide structures grafted onto the polypropylene backbone during ozonization are produced. These are decomposed at moderate temperature (50-700C) in the presence of an oxidation-reduction system based on cobalt octoate. It is then possible to initiate the radical polymerization of chloromethylstyrene and thus to carry out its grafting on the polypropylene particles.

 To improve the accessibility of the chloromethyl groups which are reactive sites for subsequent functionalizations and certain applications, the chloromethylstyrene is copolymerized with a monomer of similar reactivity such as styrene, in order to space the chloromethyl groups. It is polymerized in suspension in an organic solvent, such as dioxane.

 After polymerization, the grafted polypropylene-based resin is separated from the reaction medium by filtration and washing with pure dioxane to remove residual homopolymers. After drying, the degree of functionalization in chloromethyl groups is determined by a centesimal analysis of the chlorine.

 Chloromethylated film resins based on polypropylene having a controlled granulometry are thus obtained.

These resins can be used successfully as a replacement for Merrifield resins, because, on the one hand, they exhibit excellent dimensional stability in many organic solvents up to 100 C, probably related to the semi-crystalline nature of basic isotactic polypropylene, and on the other hand the active sites feel a great accessibility related to their skin nature
It is also conceivable to use these chloromethylated film resins in sequential peptide syntheses.

Example 11
The chloromethylated film resins of Example 10 were then used in organic synthesis as a carrier of dimethylsulfoxide (DMSO) grafted as a catalyst for the selective alkylation reaction of benzonitrile with bromomethane.

 The grafting operation of the DNSO is performed in two steps. In a first step, the chlorobenzyl groups are converted into methylbenzylsulfide groups, which in a second stage are oxidized to methylbenzylsulfoxide groups.

 A comparative study of the kinetics of this reaction with respect to those observed with supported resins of styrene divinylbenzene type functionalized at 5% and gel or macroporous type, shows that the film resins according to the invention make it possible to obtain a speed higher initial reaction than conventional resins. Thus, this initial speed is about three times greater with the compounds of the invention compared to that of the macroporous resin and is still twice that of the gel-type resin.

Example 12
The chromethylated film resins of Example 10 are quaternized with trimethylamine. The amination is carried out in suspension in methylal at the rate of 50 g of resin per 100 ml of this compound. After one hour of contact with the solvent, an aqueous solution of trimethylamine is added at a rate of 200 g: 1. The assembly is then heated for fifteen hours at 450c to obtain an aminatnon with yields generally of at least 80%. After reaction, the quaternized resin is washed with tetrahydrofuran on sintered glass and is dried under vacuum at room temperature.

 These resins may advantageously be used as ion exchange resins, especially as ion exchange resins with rapid exchange kinetics.

The excellent dimensional stability of these resins up to 100 C overcomes, advantageously the disadvantages of current resins styrene divinylbenzene type.

Example 13
By the technique described in the Applicant's patent application already cited, the particles of polypropylene are ozonized by ozonisation and the grafting of dimethylaminoethyl on these particles is carried out in suspension in heptane at 65 ° C. using a redox-based oxidation-reduction system. ferric acetylacetonate and alphahydroxybenzylphenylacetone (benzoin) to generate radicals. The film particles obtained after quaternization using dimethyl sulphate are particularly suitable as ion exchange resins and in particular as ion resins with rapid exchange kinetics.

Example 14
In a known manner, a filament yarn, whose filaments have a diameter of fourteen microns, is passed through a fluidized bed of particles of ten or twenty microns prepared according to Example 5.

 Still in a known manner, these impregnated yarns are coated by coextrusion with a polypropylene sheath.

 These yarns are advantageously used for the manufacture by molding of long fiber composite materials.

 The semi-crystalline polyolefin particles prepared according to the invention, in particular in spherical form, are characterized by a particle size as little dispersed as possible. In this way, these resins can find many applications.

 They can first be used in the form of an aqueous dispersion when these particles have for example a size equal to or less than one micron.

 Particles of dimensions between 10 and 20 microns are particularly well suited to fluidization techniques, such as surface coating, impregnation of fibers, grafting, the manufacture of reinforced or non-thermoplastic composite materials.

 Finally, with particles having dimensions of between 10 and 250 microns, film-type resins can be produced by ring grafting of functional monomer.

 In short, these particles can receive all known applications of fine particles whose dimensions are poorly dispersed.

Claims (10)

 1 / Process for the manufacture of semi-crystalline polymer particles, characterized in that it consists  first of all, to dissolve this polymer while hot and with stirring in a solvent until a homogeneous liquid solution is obtained  - then, to cool to recrystallize the polymer without showing a liquid-liquid phase separation  and finally, to eliminate the solvent.  2 / A method according to claim 1, characterized in that the polymer is isotactic polypropylene and in that the solvent is selected from the group consisting of xylene, orthodichlorobenzene, decahydronaphthalene and decane.  3 / A method according to one of claims 1 and 2, characterized in that the homogeneous polymer solution is cooled either by transferring it into a container at room temperature, or slowly in the same container dissolution.  4 / A method according to claim 1, characterized in that with stirring, is added to the homogeneous hot polymer solution of water at a temperature close to that of the polymer solution to obtain a water-in-oil emulsion before cooling.  5 / A method according to claim 4, characterized in that when the water-in-oil emulsion has been obtained, water is added to this emulsion at a temperature close to that of the emulsion, always while stirring until the phase inversion (oil in water) is obtained before cooling.  6 / A method according to one of claims 1 to 5, characterized in that the semi ~ crystalline polymer is a graft polymer.  7 / A method according to one of claims 1 to 5, characterized in that the semi ~ crystalline polymer is grafted during the dissolution and before cooling.  8 / aqueous dispersion of semicrystalline polymer, characterized in that it is formed by particles obtained by the implementation of the method according to one of claims 1 to 7.  9 / functionalized film-based resins obtained by grafting of vinyl monomers, functionalized on semi-crystalline polymer particles obtained because the implementation of the method according to one of claims 1 to 5.  10 / Ion exchange resins; characterized in that it comprises functionalized film particles according to claim 9.