FR2525492A1 - MICROPOROUS POWDERS CHARGED WITH ACTIVE PRODUCTS AND PROCESS FOR THEIR PREPARATION - Google Patents

Abstract

THE MICROPOROUS POWDERS CHARGED WITH ACTIVE PRODUCTS ARE OBTAINED BY SPRAYING IN A GAS, FOR EXAMPLE IN AIR, A HOMOGENEOUS SOLUTION CONSTITUTED BY A POLYMER AND AN ACTIVE PRODUCT, WHICH POSSIBLE CONTAINING AN ADDITIONAL INERT LIQUID. THE HOMOGENEOUS SOLUTION PREFERABLY CONTAINS A POLYMER AND AN ACTIVE PRODUCT, WHICH FORM A BINARY SYSTEM PRESENTING IN A LIQUID PHYSICAL STATE A COMPLETE MISCIBILITY AREA AND A NON-MISCIBILITY AREA. THESE POWDERS ARE CHARACTERIZED BY A POROSITY OF 60 TO 80, AN EXTERNAL FILM CONSISTING OF THE THERMOPLASTIC POLYMER WITH A THICKNESS OF 0.1 TO 1 MM AND AN OPENING DEGREE OF 2 TO 20. USE OF THESE POWDERS, IN PARTICULAR FOR THE CONTROLLED RELEASE OF ACTIVE PRODUCTS.

Description

Microporous powders loaded with active products and their process of

preparation

  The present invention relates to microporous powders

  active products for the controlled release of active products, and a process for their preparation.

  It has long been known to prepare

  in the form of powder or small granules, which are porous or microporous.

  to prepare microporous fine particles which contain

certain active products.

  It is thus described in KUNSTOFFE, vol 55, N O 5,

  year 1965 of page 389 to 390 synthetic resin foams

  which can be used for soil improvement. These are fluffy polystyrene

  a size of about 4 to 12 mm or urea-foams

  maldehyde These particles can make the soil softer and are able to absorb water to a certain extent and release it again at a later date when the soil is dry again due to lack of rain, so that they act as drainage and can regulate the soil water regime, especially in the dry regions. However, such particles are not suitable for being charged with active ingredients at first sight, active products

  which are then released in a controlled manner in the envi-

ronment.

  German Offenlegungsschrift No. 1,694,713 also discloses open pored particulate foams for use as inclusion products or carriers for various active agents. However, it is not possible to infer from this document the way of

  advantageously prepare particles charged with

  assets that are appropriate for the release of

long lasting.

  In the German patent application filed and

  in R F A 2,035,601 micro particles are described.

  polymers that have a particle size of

  2 - cules between maximum 500 and G: rliium t 0: 2 nm and which are at least one space creiux, preferably several

  hollow spaces having an average diameter of at least 200 gm.

  Also, these polyvinyl particles are not suitable for controlled release of the long life of the active products. In the published Dutch patent application 75/00873 there is finally described an antistatic agent made of polyolefins

  which can also be ground into grains or powders.

  the particles described therein, however, are not suitable for proper long-term controlled release, but instead they are added to other polymer masses, they serve as the so-called "master-batch" "masterbatch" and serve for better dispersion of the antistatic agent in

  the polymer which must acquire antistatic properties.

  It is also known to provide an impregnating agent

  powders or small porous grains which contain a

  active product Thus it is described for example in the patent

  European patent 5302 a process by which small grains are charged with an active product and by which a polyurethane film is

  close the pores Such a process is complicated and time consuming.

  Although we already know a series of powders

  microporous devices which are suitable for fixation and

  active products, there is still a need for

  microporous with which it is possible to liberate

  active products in the environment in such a way as to

  in a longer period of time. There are also

  if a need for an improved process for preparing these microporous powders that works in a simple manner

and economic.

  The object of the invention is therefore to make available

  a microporous powder which is laden with active products and which releases the active product in a period of

  longer time in a controlled and uniform manner.

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  The object of the invention is furthermore to provide

  position of the microporous powders that can be

  large quantities of active product and which, in

  of their particular structure, do not initially release a large amount of active product, even for a high initial portion of active products, to subsequently decrease

quickly in their liberation.

  The object of the invention is furthermore to provide

  position a process by which the microporous powders of the

  type mentioned are accessible in a simple and economical way.

  nomic. The object of the invention is, moreover, to provide microporous powders and a method for

  prepare, o the microporous powder, in order to improve the

  long-term fermentation, does not present a

in another matter.

  These objects are made by microporous powders

  its thermoplastic polymer, loaded with active product,

  for controlled release of the active product, which is

  with a porosity of about 60 to 80%, an outer skin consisting of the thermoplastic polymer having a thickness of about 4.1 to 1 Nom and an opening degree of about 2 to 20%, the orifices of the outer surface

  having a diameter of up to 1 gm.

  According to the invention, it is used for the pre-

  of these microporous powders loaded with active products for the controlled release of the active products a process which is characterized by the fact that it is sprayed

  in a gas a homogeneous solution of a polymer and a

  active ingredient which optionally contains an additional inert liquid.

  Porogenic active agent When using a liquid

  of additional inert, this one can be an ooro-

gene.

  In a particularly preferred form of

  the process according to the invention, a solution is

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  homogeneous mixture of a polymer and an active product, which

  a binary system which presents in the physical state a

  domain of total miscibility and a domain of non-miscibility

  where it is sprayed, in a gas which has a temperature

  Squelch below the demixing temperature, the solution having a temperature above the demixing temperature. The inert liquid may be a non-solvent for the polymer used. As appropriate, about 20 to 70% of active product is used to form the solution.

  80% of inert Quide These compositions are particularly

  advantageous when the active product is not itself pore-forming. In another particularly advantageous embodiment of the process according to the invention, one rinses

  powders after spraying.

  As a polymer, polyamide-G among others is suitable

  well, and then it can be used as an inert liquid supplement

the y-butyrolactone.

  Thermoplastic polymers that can be used

  preferably for the invention are mentioned in the

  published German Patent Application 2,737,745 and it is

  here is what was revealed in this above-mentioned application

  In this publication, a whole

  series of active products which are often referred to in this

  the publication as "functional liquids", which can be converted according to the invention together with the thermoplastic polymers into a microporous powder. Thus, as mentioned on page 89, paragraph 2 and page 90, first paragraph of the German patent application Published 2,737,745 cited, functional fluids according to the invention can be used which act as animal repellents, odoriferous agents, insecticides, drugs, odor enhancers, perfumes, pesticides, etc.

  In the examples and in the tables of the

  As indicated, a whole series of functional fluids-functional in conjunction with polymers that can be used-are expressly mentioned with reference to what is revealed therein.

  as part of this application.

  Preferably the polymer used and the product used

  tif form a system which, in the liquid physical state, exhibits a domain of complete miscibility and a field of immiscibility. A solution which is in the form of a single liquid phase is pulverized. This means that

  the solution must have a temperature that is

  above the demixing temperature of the system.

  The solution is sprayed into a gas which has a temperature below the demixing temperature below the demixing temperature, the system is two-phase, that is to say, it forms In general, two liquid phases are next to one another. It is particularly advantageous to spray the

  homogeneous solution in a gas that comes to the temperature

ordinary course.

  As gas it is possible to use air; but it is also possible to work with other gases such as

nitrogen or rare gases.

  It is particularly advantageous that the systems

  used in the liquid physical state a non-mis-

  cibilité; in this way the microporous powders acquired

  a particular pore or micropore structure

  In addition to the active product, one or more inert liquids can be used simultaneously; for this the inert liquid, the active product and the polymer must

  to form together a homogeneous solution.

  By the addition of a suitable inert liquid, the polymer and active product systems, which do not exhibit any nonmiscibility in the liquid physical state, can be converted into a system which has the physical state

  liquid a non-miscibility So it is possible by ad-

  of inert liquid is to form mainly only

  A system with a non-miscibility that is to increase the nonmiscibility, thanks to which one obtains interesting effects. By the choice of the difference in temperature between the temperature of the solution to be sprayed and the temperature

  gas in which the solution is sprayed, it is pos-

  to modify the properties of the powder.

  the choice of temperature can be used to adjust the

  powder, the type of pore volume, etc. By small differences in temperature, the shape of the

  the powder that forms in the sense of the spherical form.

  It is advantageous if the difference in temperature between the solution and the gas is as high as possible, which is why it is preferably sprayed into a gas which is

  found at ordinary temperature.

  During solidification, the powder is deposited in a more or less irregular form depending on the cooling conditions. It often still has on the outside a film of active product, through which it can

  produce a certain aptitude to become sticky Cepen-

  this ability to become tacky is not so intense

  that a separation of the different particles is impossible.

  The powder obtained in this way can instead be

  generally aim very easily at its different parts

  particles, for example by dispersion in another liquid

or also mechanically.

  It is particularly advantageous to subject the powder after solidification to washing, so that particularly fluid particles are obtained, which can be handled as dry powder, grains

  or granules For washing, a simple treatment is

  short duration with a solvent or a washing agent

  appropriate like alcohols and others.

  The viscosity of the spray solution can vary within wide limits; however it is advantageous that the

  viscosity does not exceed 5 Pa s A viscosity can be adjusted

  -7- appropriate by adjusting the concentration of the polymer,

  by the choice of the molecular weight of the polymer, by the

  and the choice of active product and liquid

  possibly used in addition.

  It goes without saying that the viscosity is adjusted to a suitable value during spraying, a value which also often depends on the spraying process, for example by the choice of the spray nozzle of the gas used, the temperature of the gas, etc.

  The polymers used in particular are

  low molecular weight mothers before a molecular weight

  up to about 40,000 daltons.

  When using inert liquids simultaneously

  it is particularly favorable to use liquid

  such as are mentioned in the German patent application 3 205 289 First of all, edible oils and

  the dietary fats named in this application,

  which expressly relate, are very suitable for many of the purposes of use, because

  in this case are non-toxic and harmless substances

  which are essential for the purposes of

more diverse.

  The gas in which the solution is sprayed according to

  according to the invention, can present conditions of pres-

  normal conditions; it is possible to work also under

  reduced pressure; but this is usually not necessary

sary.

  It was particularly surprising that it was pos-

  in accordance with the invention to prepare powders

  microporous products loaded with active product, which

  sure to release the active product in a controlled way, that is

  that is, beyond a longer period in the same quantities. The invention is applicable in a very varied manner and can be used, besides the fields of use already mentioned above, among others also for the long-term release of hormones, the most

  for animal and human medicine, in forestry

  culture and agriculture and other things of the same type.

  It is furthermore advantageous that the process of pul-

  verisation can be achieved in an extremely simple

  To atomize or spray, the

  Commonly known positive known by the process technique, as described for example in ULLMANNS ENZYKLOPADIE DER TECHNISCHEN CHEMIE, vol. I, 1951 edition, 3 edition, pages 728 to 731 or ULLMANNS ENZYKLOPADIE DER TECHNISCHEN

  CHEMIE, vol II, 1972 edition, 4 edition, pages 254 to 258.

  The preparation of the micro-powders can be carried out

  With a polymer, such as polyamide-6 and an active product, for example methylnonylketone and ybutyrolactone as inert porogens, a solution is prepared by heating. during which one can possibly agitate It is then

  advantageous to prepare a solution which has a visco-

sity of 5 Pa S maximum.

  Spraying in air or gas is a

  extremely simple process which poses no technical problem

Picnic.

  Beside the nozzles mentioned in ULLMANNS ENZYKLO-

  In addition, the nozzles as known for the preparation of the hollow fibers are suitable in the so-called "two-hole nozzles", the internal orifice can serve for the expulsion of the solution; by opening

  outside ring, a hot gas can be

  under pressure, the spray effect being

then especially improved.

  It was particularly surprising that the powders, which are prepared in the manner according to the invention, have a high proportion of internal hollow spaces.

  in which the active product and pos-

  In addition, a relatively closed surface is provided which ensures that the active product is released into the environment.

  beyond a longer time in a finely

  In this way we obtain a long-lasting action

this surprising duration.

  The surface or film of the powders, which is formed in the manner according to the invention, is relatively

  closed, so that the active product is not released pre-

  maturely and in concentrations that are too high

  release, but it has enough openings for the active product to come out of the

  powder loaded with active product to the outside.

  The present invention is illustrated by the following descriptive and nonlimiting examples

Example 1

  At about 1900 ° C., a solution consisting of 10% of polyamide-6 (viscosity of solution 2.5), 80% of γ-butyrolactone and 10% of methylnonylketone (active product) is prepared and pulverized at 2000 ° C. compressed air through a two-hole nozzle in a larger receiving tank where the ordinary temperature prevails The powder obtained has a pore volume of 62% which is determined, after extraction of the powder, by means of porosimetry

mercury.

Example 2

  A solution consisting of 10% polypropylene, 27% castor oil and 63% isopropylmyristate is sprayed into the air at about 2300 C. The polypropylene powder

  obtained at a pore volume of about 70%.

  In both examples, a filter nozzle was used.

  hollow hollow of usual structure having diameters of 1.5

0.9 and 0.65 mm.

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Claims (10)

  1. Process for the preparation of microporous powders loaded with active products for controlled release   active products, characterized by the fact that   gas in a homogeneous solution of a polymer and a   active product, which may contain an inert liquid you're extra.   2. Method according to claim 1, characterized   in that a pore-active product is used.   The process according to claims 1 and 2, wherein   terized by the fact that an inert porous liquid is gene.   4. Process according to any one of the claims   1 to 3, characterized by the fact that a homogeneous solution of a polymer and an active product, which   form a binary system presenting in the physical state   a range of complete miscibility and a field of immiscibility, and that the solution which has a temperature above the demixing temperature is sprayed into a gas having a temperature below the demixing temperature.   5. Process according to any one of the claims   1 to 4, characterized by the fact that   which is itself a non-solvent for the poly- mother employed.   6. Process according to any one of claims 1 to 5, characterized by the solution which contains 20 to 70% inert liquid.   Process according to any one of the preceding claims, characterized after spraying.   8. Process according to any one of claims 1 to 7, characterized by polymer polyamide-6. any of the claims   that one uses an active product and 30 to 80% any of the claims that the washing is done any of the claims   does that we use as 9. Process according to claim 8, characterized 11 -   in that γ-butyrolactone is used as a additional inert.   10. Microporous powders loaded with active product   made of a thermoplastic polymer for a release   controlled composition of the active product, earaeter-Jn by a porosity of 60 to 80%, an outer film consisting of the thermoplastic polymer of a thickness of 0.1 to 1 μm.   and an opening degree of 2 to 20%, the holes of the pel-   outer wing with a diameter of up to 1 m.