FR2707660A1 - Silicon elastomer system and use of the said system as agent for releasing active chlorine - Google Patents

Abstract

Elastomer system obtained by crosslinking a composition including: - (A) 100 parts by weight of an alpha , omega -di(hydroxy)diorganopolysiloxane; - (B) from 2 to 20 parts by weight of a crosslinking silane containing a hydrolysable group; - (C) from 0 to 150 parts by weight of inorganic or organic fillers; - (D) from 1 to 150 parts by weight per 100 parts of A + B + C of a solid inorganic or organic compound capable of releasing active chlorine in contact with water or moisture (preferably calcium hypochlorite); - (E) optionally a catalyst of crosslinking by polycondensation; the said composition containing at least 0.01 % of its weight of water, added and optionally generated intrinsically and optionally added extrinsically. Use of the said system as agent for releasing active chlorine, especially for water treatment.

Description

SILICONE ELASTOMERIC SYSTEM AND USE OF SAID SYSTEM

  AS ACTIVE CHLORINE RELEASE AGENT

  The subject of the present invention is a system based on a polyorganosiloxane elastomer capable of releasing active chlorine, as well as the use of said system as an agent for releasing active chlorine, in particular for the disinfection of water and in the fields hygiene and sanitary applications. According to the invention, it is an elastomeric system obtained by crosslinking a composition comprising by weight: - (A) 100 parts of an α, co-di (hydroxy) diorganopolysiloxane, of dynamic viscosity of the from 500 to 700,000 mPa s. at 25 C, preferably of the order of 700 to 20,000 mPa.s., consisting of a succession of diorganopolysiloxy units of formula R2 Si O, formula in which the symbols R, identical or different, represent alkyl radicals, alkenyls or aryls containing from 1 to 8 carbon atoms, preferably at least 80% by number of said radicals being methyl radicals; - (B) from 2 to 20 parts by weight, preferably from 3 to 15 parts by weight of a crosslinking agent of formula R Si X3 or Si X4, where R has the definition given above and X represents a hydrolyzable group ; - (C) from 0 to 150 parts by weight, preferably from 5 to 120 parts by weight of mineral or organic fillers; - (D) from 1 to 150 parts by weight, preferably from 10 to 100 parts by weight per 100 parts of A + B + C, of a solid mineral or organic compound capable of releasing active chlorine on contact with the water or moisture; - (E) optionally a catalytically effective amount of a polycondensation crosslinking catalyst; said composition containing at least 0.01% of its weight of water, preferably from 0.05 to 10% i its weight of water, supplied and optionally generated by

  intrinsic and possibly supplied extrinsically.

  The az, co-di (hydroxy) diorganopolysiloxanes (A) are essentially linear products; they can however comprise up to 2% by number of R Si O1.5 and / or Si 02 units relative to the number of diorganosiloxy units. The dynamic viscosities mentioned above are measured at 25 ° C. using a Brookfield viscometer according to the AFNOR NFT 76 102 standard.

of February 1972.

  Among the hydrocarbon radicals R, there may be mentioned the radicals:

  methyl, ethyl, propyl, trifluoro-3,3,3 propyl, cyclohexyl, cyanoethyl ...

vinyl, allyl, butenyl ...

phenyl, chlorophenyl ...

  It should be understood, according to a variant of the invention, that it is also possible to use, as polymer (A), copolymers or a mixture consisting of several polymers which differ from one another by the molecular weight and / or the nature of the

radicals linked to silicon.

  The crosslinking agent (B) has at least one hydrolyzable group such as: acyloxy of formula -O-CO R '10. alkoxy of formula -OR' amino of formula -NR1 R2 amido of formula -NR1COR2 alkenyloxy of formula -OCR1 = CHR2 aminoxy of formula -O-NR1R2

WE

  ketiminoxy of formula -O-N = CR1R2 or -O-N = C-

  1-J o R 'represents an alkyl or aryl radical having from 1 to 15 carbon atoms, R1 and R2, which are identical or different, represent alkyl or aryl radicals containing from 1 to 8 carbon atoms and T an alkylene radical containing from 4 at

8 carbon atoms.

  Among the radicals R ′, R1 and R2, mention may be made most particularly of the radicals

  methyl, ethyl, cyclohexyl, phenyl ...

  Among the radicals T, mention may very particularly be made of those of formula - (CH2) 4-;

- (CH2) 5 - ;-( CH2) 6 -...

  The crosslinking agents preferably used are the acyloxysilanes and the alkoxysilanes of formulas Rp Si (OCOR ') 4p Rp Si (OR') 4.p

  o R and R 'have the definition given above and o 0 is equal to 1 or 2.

  By way of example, mention may very particularly be made of those of formula CH3Si (OCOCH3) 3 C2H5Si (OCOCH3) 3 CH2 = CHSi (OCOCH3) 3 C6H5Si (OCOCH3) 3 CH3Si (OC2H5) 3 C2H5Si (OC2H5) 3 CH2 = CHSi ( OC2H5) 3 C6H5Si (OC2H5) 3 CH3Si (OCH3) 3 C2H5Si (OCH3) 3 CH2 = CHSi (OCH3) 3 C6H5Si (OCH3) 3 CH3Si [OCOCH (C2H5) - (CH2) 3-CH3] CF3CH2CH3S6 (OC6 (OCOCH3) 2 (OCOH (C2H5) - (CH2) 3-CH3 CH3COOSi [OCOCH (C2H5) - (CH2) 3-CH3] 3 The mineral fillers (C) can be in the form of very finely divided pigment products or non-pigmented, with an average diameter of less than 0.1 µm, such as combustion or precipitation silicas with a specific surface area generally greater than 40 m2 / g., or in the form of roughly divided products, with an average diameter of more than 0, 1 lm, such as ground quartz, diatomic silicas, calcium carbonate, calcined clay, rutile-type titanium oxide, oxides of iron, zinc, chromium, zirconium, magnesium, the different forms of alum ine, boron nitride, lithopone, barium metaborate, generally with a specific surface

less than 30 m2 / g.

  As organic fillers (C), mention may be made of polymer powders

  organic such as polyethylene, polyacrylonitrile, polyvinyl chloride ...

  Among the polycondensation crosslinking catalysts (E) which can be used, mention may be made of those based on tin, titanium and / or zirconium such as: - organotin salts of carboxylic acids such as tributyltin monooleate , 2-ethylhexanoate of tin, dibutyltin diacetate, dibutyltin dilaurate ... (a certain number of these catalysts are described in the work of NOLL entitled "Chemistry and Technology of Silicones", page 397, 2e - Academic Press 1968 -) - reaction products of organotin salts of carboxylic acids with titanium esters (US-A-3,403,753) - tin chelates (EP-B-147,323) - organic derivatives of titanium and zirconium, such as titanium and zirconic esters (US-A-4,525,565) These can be used in amounts expressed by weight of metal ranging from 50 to 300 parts per million (preferably 100 to 150 parts per million) in the in the case of a tin catalyst or from 2 to 20 parts per million (preferably from 4 to 10 parts per million) in the case of a titanium catalyst

  with respect to the set (A) + (B) + (C).

  Among the solid mineral compounds (D), mention may be made of:

  solid hypochlorites of alkali or alkaline earth metals.

  Mention may in particular be made of the commercial hypochlorites of lithium, strontium, barium and calcium; these consist of mixtures of hydrated hypochlorite,

  basic hypochlorite, carbonate ... of alkali or alkaline earth metals.

  These hypochlorites can have a triple function, that of water retentive, that of basic catalyst or basic accelerating curing agent and that

active chlorine tank.

  Particularly preferred is commercial calcium hypochlorite, which consists of a mixture of neutral calcium hypochlorite dihydrate Ca (OCI) 2,2H20 of hemibasic calcium hypochlorite Ca (OCI) 2, 1 / 2Ca (OH ) 2 5. dibasic calcium hypochlorite Ca (OCI) 2,2Ca (OH) 2

To and from CaCI2, Ca (OCI) 2, CaCO3 ...

  Among the solid organic compounds (D), there may be mentioned the compounds N-

  chlorine type: chloramine T (N-chloro-p-toluenesulfonamide) 10. chloramine B (sodium N-chlorobenzenesulfonamide) N-chlorosuccinimide trichloromelamine N-chloro derivatives of cyanuric acids such as trichloroisocyanuric acid,

  sodium dichloroisocyanurate dihydrate, ...

  15. N-chloro hydantoines such as 1-bromo-3-chloro-5,5dimethylhydantoine ...

  These solid mineral or organic compounds (D) can be used in the raw state in the form of grains or particles of the order of a few P.rm to 2 mm. The elastomer network is formed by functionalization of a, o-di (hydroxy) diorganopolysiloxane (A) by the functional crosslinking agent, hydrolysis of the X functions and crosslinking by condensation (these stages being successive or simultaneous). The water necessary for the hydrolysis reaction can be provided by the constituents of the formulation or optionally generated "in situ" at the temperature of

  crosslinking or provided by diffusion of atmospheric water vapor.

  The water provided by the constituents can come at least in part from the water of crystallization contained in the active chlorine precursors (hypochlorites in particular). The water generated "in situ" can result from the reaction of acids and bases present in the medium; these acids may in particular be those resulting from the functionalization reaction of the polymer (A) with an acyloxysilane (B); the bases may be those present for example in commercial hypochlorites such as

calcium hydroxide.

  The water necessary for crosslinking is therefore supplied at least in part by the active chlorine precursors (in particular hypochlorites) (D) themselves, which

that is the crosslinking agent (B).

  According to a variant of the invention, may also be present alongside the active chlorine precursors (D), a hardening accelerating agent (D ') containing water and / or capable of generating water; we can quote by

example:

  5. the solid hydroxides of alkali or alkaline earth metals, preferably those of lithium, barium, calcium, anhydrous or hydrated, as well as the oxides of alkaline earth metals such as barium or calcium oxides (this when the crosslinking agent (B) is an alkoxysilane or when an acid is introduced into the medium) 10. zeolites, hydrogels of natural or synthetic origin (such as those described in EP-A-314 584) in an amount allowing '' reach a total water percentage of at least 0.01%

compared to the composition.

  If necessary, a free liquid organic carboxylic acid capable of releasing water by acid-base reaction, such as acetic acid, ethanoic acid, 2-ethylhexanoic acid, can be introduced into the mixture, according to a quantity making it possible to reach a total percentage of water of at least

  0.01% based on the composition.

  Said silicone elastomer system as described above, may contain

  in addition to other additives such as in particular antimicrobial agents.

  The present invention also relates, as a new product, to the composition, comprising the constituents (A), (B), (C), (D) and optionally

  (E), as well as variants thereof, as described above.

  The crosslinking operation can be carried out at room temperature, possibly in the absence of air, in the space of 1 to a few minutes (less than 30 minutes, preferably of the order of 2 to 10 minutes); slight heating, to a

  temperature below 100 C accelerates hardening.

  The silicone elastomer system which is the subject of the invention can be in the form of matrices of various shapes, such as granules, cylinders, cubes, films, ribbons, cords, etc .; said matrices

  can optionally be integrated into cartridges.

  Said objects can be obtained by adding the solid mineral or organic compound (D), optional additional curing agents (D ') and other additives to a pasting comprising the constituents (A), (B) (C) and

  optionally (E), then shaping by extrusion, molding, coating.

  An alternative embodiment consists in dispersing the solid mineral or organic compound which is a precursor of active chlorine (D) in a part of (A) prior to its

  introduction into mash ,. or in the mixture (A) + (C).

  The elastomeric system which is the subject of the invention can be used as

  active chlorine releasing agent.

  Thus it can be used for the production of seals or films which can be used in the fields of hygiene and sanitary applications, seals or films whose antimicrobial activity, which is ensured by the release of chlorine

  active, inhibits on contact any proliferation of microorganisms.

  Active chlorine can be generated by progressive decomposition of the solid compound (D) over time, this decomposition can occur under the effects of heat, light, carbon dioxide and water; active chlorine

  can also be generated by microcracking.

  The present invention also relates to the use for the treatment of drinking water, of the above silicone elastomer system, a system in which the crosslinking agent (B) has at least one hydrolyzable group acyloxy (acetoxy in particular) and whose solid constituent precursor of active chlorine (D) is based

calcium hypochlorite.

  This system is preferably in the form of cartridges and releases the active ingredient hypochlorite Ca (CIO) 2 gradually over time,

  generally thanks to a phenomenon of micro-cracking of the silicone matrix.

  Such a system makes it possible to locally treat maintenance-free networks

  private or public water, basins, swimming pools, springs, boreholes ...

  for a long period (of the order of 1 to 4 months); at the end of their life the cartridges

can be replaced.

  The following examples are given for information only and cannot be

  considered as limiting the field and the spirit of the invention.

Example 1

  Preparation of the silicone formulation F1 A mashing is prepared by hot kneading for 3 hours at 130 ° C. of: - 100 parts by weight of oil a, co-dihydroxypolysiloxane with a viscosity of approximately 3,500 mPa.s. at 25 C - 6 parts by weight of a combustion silica (specific surface 200m2 / g) To this pasting is added: - 0.5 part by weight of rutile TiO2 then

  - 5 parts by weight of ethyltriacetoxysilane.

  Mixing at room temperature, under vacuum, for 1 Omn.

  This gives a fluid silicone formulation with a dynamic viscosity of approximately

000 mPa.s at 25 C.

Example 2

  Preparation of the silicone formulation F2 A mashing is prepared by hot mixing for 3 hours at 130 C, of: - 100 parts by weight of a, oe-dihydroxypolysiloxane oil with a viscosity of approximately 3,500 mPa.s. at 25 C - 6 parts by weight of a combustion silica (specific surface 200m2 / g) To this mashing is added:

  - 5 parts by weight of ethyltriacetoxysilane.

  Mixing at room temperature, under vacuum, for 1 Omn.

  This gives a fluid silicone formulation with a dynamic viscosity of approximately

000 mPa.s at 25 C.

Example 3

  Preparation of the silicone formulation F3 A mash of the following composition is prepared by hot kneading (3 hours at 120 ° C.): - 100 parts by weight of a, oe-dihydroxypolysiloxane oil with a viscosity of approximately 750 mPa.s. at 25 C - 6 parts by weight of a combustion silica (specific surface 200m2 / g) To this mashing is added:

  - 25 parts by weight of a diatomaceous silica.

  2.5% by weight of a crosslinking agent (ethyltriacetoxysilane) and a titanium catalyst are added as a mixture to this pasting in sufficient quantity to

  obtain a product containing approximately 5 ppm of titanium.

  This gives a fluid silicone formulation with a dynamic viscosity of approximately

8,000 mPa.s at 25 C.

Example 4

  Preparation of the silicone formulation F4 A paste of the following composition is prepared by hot mixing (3 hours at 120 ° C.): - 100 parts by weight of oil a, co-dihydroxypolysiloxane with a viscosity of approximately 3,500 mPa.s. at 25 C - 6 parts by weight of a combustion silica (specific surface 200m2 / g) To this mashing is added:

  - 25 parts by weight of a diatomaceous silica.

  2.5% by weight of a mixture of two crosslinkers (methyltriacetoxysilane + ethyltriacetoxysilane 77/23 by weight) and a titanium catalyst are added in a sufficient amount to obtain a product containing

about 5 ppm titanium.

  This gives a fluid silicone formulation with a dynamic viscosity of approximately

000 mPa.s at 25 C.

  Preparation of matrices from silicone formulations F1 to F4 Calcium hypochlorite of PROLABO origin, with 70% of active chlorine, is ground in a mortar away from air humidity, then sieved in order to '' get cuts

  different particle sizes shown in the table below.

  20g are introduced into a 100 ml reactor with a scraping anchor. of a mixture consisting of the desired quantities appearing in said table, of calcium hypochlorite of selected particle size and of silicone formulation F chosen (quantities

  expressed in% by weight relative to the total mass of 20g.).

  The mixture is kneaded under vacuum (approximately 100 to 500 Pa) for a few minutes, in order to homogenize and degas the mixture, then the product is quickly poured into

  one or more molds whose size and shape are those of the desired objects.

  After ten minutes at room temperature the product is crosslinked and takes one of the following forms: - cylinder 3cm high xl, 7cm in diameter (R) - parallelepiped of 2.5cm x 2.5cm x 3cm (P1) - parallelepiped of 5cm x 2.5cm x 1cm (P2) - parallelepiped of 5cm x 2.5cm x 0.5cm (P3)

Example 5

  A mashing is prepared by hot mixing for 3 hours at 130 ° C. of the following mixture: - 100 parts of cc oil, oe-dihydroxypolysiloxane with a viscosity of 3,500 mPa.s. to C - 6 parts by weight of a combustion silica (specific surface 200m2 / g) To this mashing is added:

  - 0.5 part by weight of rutile TiO2.

  Part A is prepared at room temperature, by mixing 280g. of

  the above mash with 300g. calcium hypochlorite.

  This mixture is introduced into the first compartment of a cartridge

  bicoposant (50/50 by volume), equipped with a static mixer.

  A Dartie B is prepared by mixing at room temperature 387g. of

  the above mash, with 33g. of ethyltriacetoxysilane.

  This mixture is introduced into the second compartment of the two-component cartridge. Parts A and B are extruded from the cartridge (at a pressure of 6 bars), which

  are thoroughly mixed in a few minutes using the static mixer.

  At the outlet of the mixer, the product is molded directly in molds of

desired shape.

  Examples 6 to 11 Monitoring the kinetics of release of active chlorine Each matrix is immersed in a closed container containing 200 ml of distilled water, water which is changed every 7 days. Regularly take 2ml of immersion water and dose the active chlorine contained therein. This assay is carried out by potentiometry according to the method described in "Methods of analytical chemistry" by G. CHARLOT -p. 695 - (MASSON. Et Cie, Editeurs, 4th

editing).

  This dosage makes it possible to trace the curves Q / Q0 = f (t), where Q0 represents the load

  initial in Ca (CIO) 2 and Q the amount of Ca (CIO) 2 released at time t.

  The results of these measurements are given by the attached curves: - Figure 1 represents the curve relating to Example 6 - Figure 2 represents the curve relating to Example 7 - Figure 3 represents the curve relating to l Example 8 - Figure 4 represents the curve relating to Example 9 - Figure 5 represents the curve relating to Example 10 Figure 6 represents the curve relating to Example 11 eAD oRIGI NA

BOARD

  Formulation Ca (CIO) 2 Times Form Example of silicone of of n Type% particle size% mix the (weight) (rm) (weight) (mn) matrix

6 F2 50 200-500 50 4 P1

7 F1 70 630-800 30 8 R

  8 F3 70 200-250 30 2 R m9 F3 70 400-500 30 3 P2

F3 60 630-800 40 2.5 P2

11 F4 70 630-800 30 2 P3

Claims (9)

  1) Elastomeric system obtained by crosslinking a composition comprising by weight: - (A) 100 parts of a ca, co-di (hydroxy) diorganopolysiloxane, of dynamic viscosity of the order of 500 to 700,000 mPa s. at 25 C, preferably of the order of 700 to 20,000 mPa.s., consisting of a succession of diorganopolysiloxy units of formula R2 Si O, formula in which the symbols R, identical or different, represent alkyl radicals, alkenyls or aryls containing from 1 to 8 carbon atoms, preferably at least 80% by number of said radicals being methyl radicals; - (B) from 2 to 20 parts by weight, preferably from 3 to 15 parts by weight of a crosslinking agent of formula R Si X3 or Si X4, where R has the definition given above and X represents a hydrolyzable group ; - (C) from 0 to 150 parts by weight, preferably from 5 to 120 parts by weight of mineral or organic fillers; - (D) from 1 to 150 parts by weight, preferably from 10 to 100 parts by weight per 100 parts of A + B + C, of a solid mineral or organic compound capable of releasing active chlorine on contact with the water or moisture; - (E) optionally a catalytically effective amount of a polycondensation crosslinking catalyst; said composition containing at least 0.01% of its weight of water, preferably 0.05 to 10% of its weight of water, supplied and optionally generated by   intrinsic and possibly supplied extrinsically.   2) elastomer system according to claim 1) characterized in that the crosslinking agent (B) has at least one hydrolyzable acyloxy group,   alkoxy, amino, amido, alkenyloxy, aminoxy, ketiminoxy ...   3) elastomer system according to claim 1) or 2) characterized in that   the solid compound (D) is a solid hypochlorite of alkali or alkaline metal earthy.   4) elastomer system according to any one of claims 1) to 3)   characterized in that the crosslinking agent (B) has at least one hydrolyzable acyloxy group and in that the solid compound (D) is hypochlorite of commercial calcium.   ) Elastomer system according to any one of Claims 1) to 4)   characterized in that it also contains a hardening accelerating agent containing water or capable of generating water, in an amount making it possible to reach a total percentage of water of at least 0.01% by compared to the composition. 6) Silicone composition comprising by weight: - (A) 100 parts of an α, co-di (hydroxy) diorganopolysiloxane, with dynamic viscosity of the order of 500 to 700,000 mPa s. at 25 C, preferably of the order of 700 to 20,000 mPa.s., consisting of a succession of diorganopolysiloxy units of formula R2 Si O, formula in which the symbols R, identical or different, represent alkyl radicals, alkenyls or aryls containing from 1 to 8 carbon atoms, preferably at least 80% by number of said radicals being methyl radicals; - (B) from 2 to 20 parts by weight, preferably from 3 to 15 parts by weight of a crosslinking agent of formula R Si X3 or Si X4, where R has the definition given above and X represents a hydrolyzable group ; - (C) from 0 to 150 parts by weight, preferably from 5 to 120 parts by weight of mineral or organic fillers; - (D) from 1 to 150 parts by weight, preferably from 10 to 100 parts by weight per 100 parts of A + B + C, of a solid mineral or organic compound capable of releasing active chlorine on contact with the water or moisture; - (E) optionally a catalytically effective amount of a polycondensation crosslinking catalyst; said composition containing at least 0.01% of its weight of water, preferably 0.05 to 10% of its weight of water, supplied and optionally generated by   intrinsic and possibly supplied extrinsically.   7) silicone composition according to claim 6) characterized in that the crosslinking agent (B) has at least one hydrolyzable acyloxy group,   alkoxy, amino, amido, alkenyloxy, aminoxy, ketiminoxy ...   8) silicone composition according to one of claims 6) or 7) characterized   in that the solid compound (D) is a solid alkali metal hypochlorite or alkaline earth.   9) silicone composition according to any one of claims 6) to 8)   characterized in that the crosslinking agent (B) has at least one hydrolyzable acyloxy group and in that the solid compound (D) is hypochlorite of commercial calcium.   ) Silicone composition according to any one of claims 6) to 9)   characterized in that it additionally contains a hardening accelerating agent containing water or capable of generating water, in an amount making it possible to reach a total percentage of water of at least 0.01% relative to at the composition.   11) Process for preparing the elastomer system which is the subject of one   any one of claims 1) to 4) by crosslinking at room temperature of   the silicone composition forming the subject of any one of claims 6) to   ). 12) Use of the elastomer system which is the subject of any one   of claims 1) to 4) as an active chlorine releasing agent.   13) Use of the elastomer system which is the subject of claim 4)   for the treatment of drinking water.