AU622462B2 - Iodine-containing organopolysiloxane composition - Google Patents

Description

-s A 1 11 11- 1. I I .14 1 11 _-1111111 11", 11 IL I

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2 462 COMMONWEALTH OF AUSTRLA PATENTS ACT 1952 QMWLXTBKPflQ NAME ADDRESS OF APPLICANT: Rhone-Poulenc Chimie Quai Paul Doumner 92408 Courbevoie France NAME(S) OF INVENTOR.(S): t 4t '$4 $44 It 4 4 4 Guy CYPRIEN Alain FISCH Johnny HAGGIAGE Hugues PORTE Thierry PRAZUCK Ghislaine TORRES ADDRESS FOR SERVICE: DAVIES COLLISON Patent Attorneys 1 Little Collins Street, Melbourne, 3000.

4* 4 4 II 4 t COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED: Iodine-containing organopolysiloxane, composition The following statement is a fulli performing it known to me/us:description- of this invention, including the best method of by Was 4. The basic application......... referred to in paralpg ph 3 of this Declaation w cation...... made in a Convention country in respect of the invention the subject nrt pc ad date Dered t nt-Fons this 29 day of MAY 1'989 Si u of d Capital 1.210,000.000 F Signature of dedrant( no R.C.S. Nanterru a 6,1 014 5?6 tletation required) 25, Qai Pau er 92408 COU 8hVulE Bernard T Note: Initial ,al alterat ev -2 The present invention relates to iodine-containing organopolysiloxane compositions, and to treating water for domestic use and for drinking using such compositions.

It is estimated that there are at present several hundred million people in the world with a deficiency or lack of iodine. The most affected geographical zones are latin America, in particular along the Cordillera of the Andes and virtually all the non-coastal countries in Africa and Asia (Pakistan, India, Nepal, China, Laos, and so on).

The main pathological consequences of iodine deficiency are well known. These are essentially, on the one f0 4 S hand, goitre and its complications, amongst which i difficulties in swallowing, respiratory disorders, cancer formation and the collateral circulation may be mentioned, S 15 and, on the other hand, hypothyroidiso and its complications, amongst which cretinism, brain disorders, premature births, miscarriages and congenital anomalies may be mentioned.

Though lack of iodine has disappeared in the f industrialized countries as a result of the iodization of cooking salt, this is not at all the case in the developing countries, where the two main actions so far taken have remained ineffective.

These actions essentially comprise, on the one hand: -the iodization of cooking salt: this is ineffective in most developing countries, because very often salt consumption is very low, the distribution channels for

A

W_ k. ftI t( t f Sft e ffC ft lA Ar tCt Cs C C f.

C C.

C f

(I

t Aft

(I

L

iC C C ft salt across the trade and commerce networks are virtually non-existent, and, finally, in the tropics, the iodine added to the salt escapes rapidly, unless it is perfectly packaged.

and, on the other hand: the intramuscular injection of iodized oil: this injection has the advantage of having a deferred action (retard action), but it also has disadvantages, in particular the risks of infection, the risks of an iodine allergy, and the risks of hyperthyroidism or hypothyroidism induced by the injection of a necessarily supra-physiological dose.

Belgian Patent BE-A-889,680 has described the introduction of oligo elements, including iodine, into the drinking water of ruminants, in the form of a dispersion in a binder such as, for example, plaster of Paris. A 15 diorganopolysiloxane can be added in order to retard the diffusion of the oligo element. The use of iodine and iodine compounds for disinfecting or purifying water is also well known. By way of example, American Patents US-A-2,347,567, US-A-2,743,208 and US-A-3,408,295 may be mentioned.

20 There is also a very large number of patents which describe the utilization of polymeric systems, in particular of silicones, for the controlled release of an active principle by means of, for example, a transdermal system (American Patent US-A-4,053,580), or by buccal absorption especially for ruminants (French Patent FR-A2,560,768).

t

V

V

1.

4 Finally, United States Patent US-A-4,384,960 describes the placing of tablets of iodine 12 into a plastic bottle into which water penetrates through a porous membrane of polymer. The water dissolves the iodine. The role of the membrane is merely to keep the iodine tablets in the bottle.

In addition, it is simply suggested that it is possible to introduce iodine (I2) into the bottle within a liquid dispersion of silicone or of a dimethylsiloxane elastomer and then to cause these to cure. This indicated solution is not feasible technically because, on the one hand, 12 is a well known inhibitor of the curing catalysts for silicone 4, elastomers which are vulcanizable at ambient temperature (see in particular the publication by W.D. MORAIN et al. Plastic 00o oo and Reconstructive Surgery 59, 2, 215-222 (1977)) and, on the 15 other hand, 12, is highly volatile and sublimes during the i4 crosslinking of the silicone elastomers under the action of heat.

oft t Moreover, there is no control of the release of "IAc iodine in this system, and the iodization of the water takes place by discontinuous or continuous addition of a few drops of highly iodized (saturated) water contained in the bottle into a receptacle of any type which contains untreated water.

It is clear that the solution proposed by US-A-4,384,960 is Simperfect, in particular because this is an individual technique which, like the intramuscular injection of iodine, requires education and a massive mobilization of I t a S 5 populations.

It is the object of the present invention to provide an iodine-containing silicone composition which, after heating (that is to say its transformation into an elastomer), can be used for the continuous treatment of water for domestic use, in particular in the water supply and treatment systems in wells and boreholes, which allows the distribution (release) of a controlled quantity of iodine suitable for assuring, on the one hand, collective treatment of the various manifestations caused by lack of iodine and, on the other hand, prophylaxis of these manifestations.

The iodine-containing silicone composition of the invention, after having been heated (transformed into an Selastomer) and immersed in appropriate fashion in the 15 water to be treated, in particular the wells and boreholes, 0° P distributes (releases) in a continuous manner, preferably over at least one year, an appropriate quantity of iodine in a form and at a therapeutically active and effective dose l.r:vel for treating the various illnesses caused by lack of S 20 iodine.

The iodine-containing silicone compositions of the 3w1' invention, when immersed (in the form of an elastomer) in appropriate fashion in the places containing the water to be treated, have no undesirable and harmful secondary action in 25 chemical and biological terms on the water which is treated.

The iodine-containing silicone elastomer of the L J f _0 i 6 invention is in a form adapted to the surroundings in which the water to be treated is located, and, in particular, to the wells and/or boreholes comprising a system for introduction into the wells and/or boreholes which permits easy replacement of the cured elastomer.

The new silicone composition is pasty and pumpable, at least before the incorporation of the iodized compound.

The silicone composition of the present invention contains: SII 4 ILi

L*

4 tI ii A) a diorganopolysiloxane oil having a viscosity of less than 300,000 mPa.s at 25 0

C,

B) an inorganic filler, C) an organic peroxide and D) at least one organic and/or inorganic watersoluble, non-toxic iodine compound in a form which is solid or liquid at ambient temperature.

The present invention also provides elastomers obtained from the composition of the present invention (after this composition has been heated) and a process for the treatment of water for domestic use using the elastomer.

As an inorganic compound of iodine, with the exception of molecular iodine 12, it is possible to use, alone or as a mixture: the iodides or iodates of the general formulae: (I-)a and (I13-)a t 4t 4 44 44i 4.

I 44

LII

i 4 I 4 4 4*i 44, i 4 1 Vi I r 1 i

C

s 7 4 4 44 1 4 446 S4 4r 4 94 4 0 4 44 in which a is an integer greater than or equal to 1 and M is a cation which can be selected from an alkali metal such as sodium and potassium, an alkaline earth metal such as magnesium and calcium, a transition metal such as iron and manganese and a quaternary ammonium (NY 4 whose radicals Y are identical or different and represent a linear or branched

C

1 -C20alkyl radical or a hydrogen atom, such as the ammonium ion NH 4 The cations Ma+ and NY 4 are selected in such a way that the corresponding iodide or iodate is a solid or liquid at ambient temperature, is soluble in water and is non-toxic.

The iodides and iodates used can in particular be those of the formulae: Nal, NaI0 3 15 KI, KIO 3 MgI 2 MgI 2 .8H 2 0, Mg(I0 3 2 .4H 2 0,

NH

4

I,

Fel2.4H20 20 MnI 2 These salts can contain water of hydration or water of crystallization.

As an iodine compound which is simultaneously organic and inorganic, it is possible to use, for example, calcium iodobehenate of the formula:

(C

2

H

4 1ICO 2 )Ca .544 4 4 4 44i 4* 4 4 44 c4 4 4- 4 44 4 4 6 I i a ii i -8 As an organic compound of iodine, iodinated polyvinylpyrrolidone may be mentioned.

For reasons of facilitating operation, solid iodine compounds are preferred, and NaI and KI0 3 are particularly preferred amongst these.

All the iodine compounds, such as those defined above, release iodine in a non-toxic and therapeutically effective form when they are in solution in the water to be treated. A non-toxic iodine compound is to be understood, according to the invention, as a compound which, in solution, is not toxic in the dosages specified by the present invention.

An iodine compound. soluble in water is to be understood as a compound having a solubility of at least 500 o ^15 mg/l at ambient temperature.

In general, 5 to 130 parts and preferably 10 to parts of iodine compound are used per 100 parts of oil

S(A).

Especially in the developing countries, the water for domestic use (for drinking, washing, irrigation, etc.) is S' essentially provided by two types of structure, namely wells and boreholes.

SFor obvious reasons of cost, effectiveness and t hygiene, a new water point is frequently created by means of a borehole.

A borehole is an air column bored through compact i V! -9rocks for a depth generally between 20 and 100 metres and with a diameter of at least abuut 10 cm. The water infiltrates this column through fissures or various interstices. The immediately available reserve of water thus consists of a column of 10 to 70 metres, generally 30 to metres, in height and is extracted, for example, by means of a submerged pump.

This water is renewed principally as a function of usage of the borehole, which depends on the season. In effect, the borehole is traditionally used less in the rainy season. By contrast, in the dry season, the borehole rt delivers, for approximately 10-12 hours per day, a quantity it t t of between, say, 5 and 10 m 3 per day over a period of about *titsix months.

t, t 15 As a general rule, a well can dry out twice during the day during the dry season, which corresponds, according to these mean statistical data, to a maximum usage of 5 to m 3 Numerous studies show that, in the zones where goitre i is highly endemic, the pre-existent level of iodine equivalent in the water from boreholes or wells is less than 2 micrograms per litre (2 It is estimated at present that a daily addition of about 100 Ag iodine equivalent per 14 1 day and per person would be sufficient for preventing development of endemic goitre, and about 150 Ag would undoubtedly be sufficient where there is regular consumption i f1 10 of goitrogenic substances. On the other hand, acute iodine poisoning can be responsible for neurological irritation, hyperthyroidism or hypothyroidism.

It is accepted in medical practice that the absorption of a dose of 3 grams of iodine equivalent by an adult person in one administration does not cause any secondary effect.

Consequently, the ability to provide an individual with 20 to 200 Ag, preferably about 100 Ag, of iodine equivalent per day constitutes the desired goal.

Since it is known that an adult individual absorbs on r average 2 litres of water per day, and on the basis of the 1 above data (a borehole having a delivery rate of 600 it thus appears desirable that one litre of treated water should %sol o 4: 15 contain about 50 jg/l of iodine, which corresponds to 50 Ag o of iodine equivalent per litre and per person, which requires the silicone elastomer to distribute 720 mg/day of iodine equivalent or 270 g of iodine equivalent for distribution trz over a year.

The system of controlled iodine release forms part of S2, 0 the matrix systems, in which the diffusion of the active principle is normally governed by Fick's law, that is to say i by half-order diffusion kinetics for only 60% by weight of the active principle. Beyond 60%, there is exhaustion of the matrix, and the diffusion flows are greatly diminished. In a surprising and unexpected manner, it has been found that the i

I

'iif ii silicone matrix system according to the invention releases iodine according to 0-order kinetics in a continuous manner, even until 80% by weight and more of the iodine compound has been released.

The considerable advantage provided by the silicone matrix is thus that it is very easy to extrapolate the continuous diffusion of the active principle after measuring the quantity released at the end of at least one month, since it is known that the diffusion kinetics are 0-order and that at least 80% of the iodine compound will be released in accordance with these kinetics.

For keeping the release of the active principle under 9 control, it is advantageous to provide the silicone matrix in the form of elementary modules (elements) of various forms O O 15 such as cubes, rectangular parallelepipeds, cylinders or spheres, the fundamental parameters of which are as follows: the nature of the iodine compound the mean diameter (particle size) g of the o 0o S00"40 particles of the iodine compound in the preferred case where the latter is a solid, the content t of the iodine compound within the matrix and the surface/volume ratio R of the module.

The nature of the iodine compound and its particle size define the diffusion rate v of the active principle across the matrix.

4 12 The smaller g, the lower is v, and vice versa.

The greater t, the higher is the flow of active principle, and vice versa.

The greater R, the higher is the flow of active principle, and vice versa.

A person skilled in the art can, from routine experiments, without difficulty and rapidly arrive at the desired result by extrapolating the theoretical elution time which will correspond to the real diffusion time of the active principle.

For NaI and KI03, which are the preferred iodine compounds, g, t and R can advantageously be selected within the following ranges: g between 1 and 300 m, t between 10 and 100 parts by weight of iodine compound per 100 parts of and R between 0.5 and 50 for a cylindrical form.

Moreover, it is desirable for the iodine compound to be homogeneously dispersed within the matrix.

In all the following or preceding text, parts and percentages are by weight, unless otherwise stated.

More precisely, the present invention relates to a silicone composition containing: 100 parts of a diorganopolysiloxane oil (or a mixture of oils), whose viscosity at 25 0 C is less than 300,000 mPa.s,

I

L.

c I i 13 5 to 90 parts Z an inorganic filler, preferably a siliceous filler, selected from pyrogenic silicas and precipitated silicas, 0.1 to 6 parts of an organic peroxide, 5 to 130 parts, preferably 10 to 90 parts, of a water-soluble and non-toxic organic and/or inorganic iodine compound which is solid at ambient temperature, and 0 to 20 parts, preferably 1 co 15 parts, of an antistructuring agent.

Advantageously, the compositions such as that defined above have a penetration ranging from 80 to 400 (measured according to French Standard NF T 60-132) before the o incorporation of the organic and/or inorganic iodine o compound. Such compositions are pasty and pumpable, at least 15 before the incorporation of the iodine compound.

*o 0 The oil (or the mixture of oils) mentioned under A has a viscosity of between 500 and 300,000 m.Pa.s. at; S-C, preferably of between 800 and 250,000 m.Pa.s at 250C. These S oils are linear polymers consisting essentially of a succession of units of the formula R 2 SiO, blocked at each end 4 t of their chain by units of the formula R 2 R'SiOO.5, in which the symbols R, which can be identical or different, represent Shydrocarbon radicals which have 1 to 8 carbon atoms and which are unsubstituted or substituted by halogen atoms and/or cyano groups, the symbo R' having the meaning of the symbols R or representing a hydroxyl radical, an alkoxy

I'

It s, i 14 i 4 4 *4 4 44 4 4 radical having 1 to 4 carbon atoms or a P-methoxyethyl radical. It is, however, not excluded that these oils contain small quantities, representing at most 1% in number, of units of the formulae RSiOI.5 and/or Si0 2 R having the meaning given above.

It is to be understood that, when the composition consists of a mixture of oils one of these oils can have a viscosity higher than 300,000 m.Pa.s, for example between 300,000 and 500,000 mPa.s at 25 0 C, but that the mixture of oils does not have a resulting viscosity higher than 300,000 mPa.s at 2F"C.

The hydrocarbon radicals, which are unsubstituted or substituted by halogen atoms or cyano groups, have 1 to 8 carbon atoms and are represented by the symbols R, comprise: 15 alkyl and halogenoalkyl radicals having 1 to 3 carbon atoms, such as the methyl, ethyl, propyl, isopropyl and 3,3,3-trifluoropropyl radicals, alkenyl radicals having 2 to 4 carbon atoms, such as the vinyl, allyl and buten-2-yl radicals, cycloalkyl and halogenocycloalkyl radicals having to 6 ring carbon atoms, such as the cyclopentyl, cyclohexyl, methylcyclohexyl and chlorocyclohexyl radicals, imnonuclear aryl and halogenoaryl radicals having 6 to 8 carbon atoms, such as the phenyl, tolyl, xylyl, chlorophenyl, dichlorophenyl and trichlorophenyl radicals, and 4

I

44I 15 cyanoalkyl radicals, the alkyl moieties of which have 2 to 3 carbcn atoms, such as the *-cyanoethyl and cyanopropyl radicals.

As concrete examples of alkoxy radicala having 1 to 4 carbon atoms and represented by the RI radicals, the methoxy, ethuL'cy, n-propoxy, isopropoxy and n-butoxy radicals may be mentioned.

As an illustration of the units essentially constituting the diorganopolysiloxane oils A, the R 2 SiO units of the formulae: t I I

I

S it-.

I I 5.5 (I SI

(CH

3 2 SiO

CH

3

(C

6

H

5 );Sio

CF

3

'CH

2

CH

2

(CH

3 )Si0

(CH

3 (CH2 CH) SiO

(C

6 11 5 2 SiO

NC-CH

2

CH

2

(CH

3 SiO

C

6

H

5

(CH

2 =CH) SiC

NC(CH

2 3(CH 3 )Sio and the R 2 R'SiQ 0 .5 units of the formulae: (1CH 3 3 Si0 0 5

CH

3

(C

6

H

5

(CH

2 =CH) SiO 0

HO(CH

3 2 Si0 0 5

CH

3 0(CH 3 2 Si0 0 5

CH

3

OCH

2

CH

2

O(CH

3 2 Si0 0

CH

2

=CH(CH

3 2 Si0 0 5

HO(CH

3

(CH

2 =CH)SiO 0

CH

3 0HI 2 0(CH 3 2

(CH

3 2

C

6

H

5 Si0 0 V SI 411 I may be mentioned respectively.

Preferably, dimethylpolysilo-xane oils containing a small quantity of vinyl radicals, representing for example 54

A

I

1.

ineffective in most developing countries, because very often salt consumption is very low, the distribution channels for -16 0.005 to 0.5% by weight of the oils, are used; these vinyl radicals are present in the form of units of the formulae

CH

3

(CH

2 =CH)SiO aid/or (CH 3 2

CH

2 =CHSiO,.5, and the oils are blocked by units of the formulae (CH 3 3 Si0 0 .5 and/or

(CH

3 2

CH

2 =CHSiO "he diorganopolysiloxane oils mentioned under A are commercially available from the silicone manufacturers; moreover, they can be easily produced by methods already known. Thus, one of the most widely used methods comprises polymerizing diorganocyclopolysiloxanes by means of catalytic quantities of alkaline or acidic agents. In the course of this polymerization, the following are added: 1 (if R' R) dic yqg.polysiloxanes of low molecular weight of the formula R 3 SiO(R 2 SiO)xSiR 3 where x 2 15 has a value sufficient to lead to a viscosity ranging from to 390 mPa.s at 25 0

C;

2 (if R' OH) water and/or an oil of the formula

HOR

2 SiO(SiR 2 O)ySiR 2 0H, where y has a value sufficient to lead Sto a viscosity ranging from 5 to 200 mPa.s at 25 0

C;

3 (if R' alkoxy or CHCH 2 CH2C0 the corresponding alcohol R'H and/or an oil of low molecular weight of the formula R'R 2 SiO(R 2 SiO)zSiR 2 where z has a value sufficient to lead to viscosity ranging from 0.5 to 120 mPa.s at 25 0

C.

Sro Preferably, the polymers obtained are purified by removing, at a temperature generally above 70 0 C and under a pressure generally below atmospheric pressure, the i especially for ruminants (French Patent FR-A2,560,7 6 8 17 17 unconverted starting compounds in order to shift the equilibrium of the polymerization reaction, as well as the polymers of low molecular weight which may have been formed in this reaction. It is recommended to neutralize the alkaline or acidic agents used as poly:nerization catalysts before the volatile products are distilled off.

The inorganic fillers mentioned under B areAused in a ratio of 5 to 90 parts, preferably 10 to 80 parts, per 100 Darts of oil mentioned under A.

These fillers can be in the form of very finely dispersed products, the mean particle diameter of which is less than 0.1 micrometre. These fillers include pyrogenic Ssilicas and precipitated silicas; their specific BET surface area is in general greater than 40 m 2 /g.

These fillers can also be in the form of more coarsely dispersed products of a mean particle diameter greater than 0.1 micrometre. Examples of such fillers which may be mentioned are crushed quartz, diatomaceous earths and calcined clay, their specific surface area being generally 20 less than 30 m 2 /g.

o These fillers can have been superficially modified by treatment with various organosilicon compounds conventionally used for this purpose. These organosilicon compounds can thus be organochlorosilanes, diorganocyclopolysiloxanes, hexaorganodisiloxanes, hexaorganodisilazanes or diorganocyclopolysiloxanes (French -0 <T O arai ngnrlgrae hn4 "g imperfect, in particular because this is an individual technique which, like the intramuscular injection of iodine, requires education and a massive mobilization of i1 -i

IIF

18 Patents 1,126,884, 1,136,885 and 1,236,505; British Patent 1,024,234). The treated fillers contain, in the majority of cases, 3 to 30% of organosilicon compounds, relative to their weight.

The fillers can consist of a mixture of several types of fillers of different particle size distribution; thus, for example, they can consist of 30 to 70% of finely dispersed silicas of a specific BET surface area greater than m 2 /g and 70 to 30% of more coarsely dispersed silicas of a specific surface area of less than 30 m 2 /g.

The quantities of treated silicas are advantageously present in a ratio of at least preferably of the quantities of silicas used.

It C The antistructuring agents mentioned under E are used t t t in a ratio from 0 to 20 parts, preferably 1 to 15 parts, per 100 parts of the diorganopolysiloxane oils mentioned under A.

Their presence prevents the compositions from undergoing an evolution in the course of time, which evolution manifests itself generally by a reduction in the penetration values.

20 They are selected in most cases from amongst: diorganopolysiloxane oils of low viscosities of the order of 5 to 500 mPa.s at 25 0 C, with each end of their chain S°I blocked by a hydroxy radical and/or an alkoxy radical having 1 to 3 carbon atoms. The organic radicals bound to the silicon atoms of these oils are preferably methyl, ethyl, vinyl, phenyl or 3,3,3-trifluoropropyl radicals.

By way of concrete examples of these oils, the i following oils may be mentioned chemical and biological terms on the water which is treated.

The iodine-containing silicone elastomer of the .119 aw-dihydroxy'dimethylpolysiloxanes, ac)-dihydroxymet-hylphenylpolysiloxafles, aw-dimethoxydimetI-hylpolysiloxanes, a w-dimethoxymethylphenylpolys ilo:.anes, having 3 to 12% of hydroxy or methoxy radicals, diphenylsilanediol and the silanes of the formulae: ~(CH -C C H Si(CH) 2

IS

(CM~(C -C (C CC 32 2 3 The organic peroxides mentioned under are used in a ratio of 0. 1 to 6 parts, preferably 0.15 to 4 parts, per 100 parts of the oil Theze are organic peroxides conventionally used for curing hot-vulcanized silicone elastomers. More especially, these peroxides are benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, dicumyl Jperoxide, 2, 5-bis- (t-butylperoxy) jJ) 15 t-butyl perbenzoate, di-t-butyl peroxide, cumyl t-butyl peroxide, t-butylperoxy isopropyl carbonate, l,l-bis-(tbutylperoxy)...3,3,5-tri-methylcyclohexale, cumyl a,a '-dimethyl-p-methylbenzyl peroxide and a, a -bis- (tbutylpveroxy) -diisopropylbenzene.

These peroxides decompose at soznietimes different temperatures and rates. They will therefore be selected

LA

(i)a and (I3-)a 20 as a function of the curing method adopted for the compositions according to the invention.

Further adjuvants can be used in the compositions according to the present invention for the purpose of improving their workability or the mechanical properties of the elastomers ob-.ained. These adjuvants include, for exmnple, silanes of the formulae given below, and their products of hydrolysis or partial cohydrolysis: CH CH-CH 0(CH Si(OR") 2 2 23 3 t i t

CM

2 =C-o0)(CMH2) 3 s1(0") 3

CH

2 =CH-Si(OR") 2 3 The symbols R" represent methyl, ethyl, n-propyl 10 or p-methoxyethyl radicals and the symbol represents a hydrogen atom or the methyl radical.

By way of concrete examples of these silanes, those of the following formulae may be mentioned: CH cH-CH 0(CH Si(OCH 2 2 23 33 0 CH2=C(C 3 )COO(CH) 3Si(OCH 3 3

CH

2 =CHSi(OCH 2

CH

2

OCH

3 3

I

San Inorganu, it 15 1 iodobehenate of the formula:

(C

21

H

4 aICO 2 )Ca E i RA4I -3 S r -21- These adjuvants are used in a ratio of 0 to parts, preferably 0.05 to 4 parts, per 100 parts of the diorganopolysiloxane oils A.

The preparation of the compositions according to the invention is carried out by intimate mixing of the various constituents A, B, C, D and E. This mixing takes place in apparatus appropriately used by rubber manufacturers. Nevertheless, in view of the choice of constituents, it is much easier to arrive at homogeneous mixtures by less powerful means and within a shorter time than for "the preparation of usual organopolysiloxane compositions i which contain diorganopolysiloxane rubbers in place of the oils A.

Sw h In particular, cylinder mixers cannot be used, which is an advantage since they consume time and energy.

By contrast, continuously or discontinuously running S kneaders or mixers with cylindrical sleeves fitted with screws may be used; in these mixers with cylindrical sleeves, the screws turn and can also be subjected to toand-fro movements.

The various constituents can be introduced into i t. the abovementioned types of apparatus in any order.

Nevertheless, if the mixtures of the constituents are heated to temperatures above 60-80°C, for example with the object of accelerating the wetting of the fillers B by the oils A and/or by the antistructuring agent mentioned under E (which allows shortening of the time of

SJI

hygiene, a new water point is frequently created by means of a borehole.

A borehole is an air column bored through compact i 22 occupation of the apparatus), it is then necessary to add the organic peroxide C last and not until the temperature of the mixtures has fallen again to a suitable level. It is also preferable in general to introduce the iodine compound at a temperature of between 20 and The compositions according to the present invention are easy to handle and, in particular, can be introduced into the feed systems of moulding presses by simple pumping with th© aid of pumps, for example piston 10 pumps. They can they can then be cured in pieces of any forms and edimensions by the traditional moulding techniques such as transfer moulding, compression moulding or injection moulding, it being understood that thhe moulding equipment used does not have to be as heavy and expensive as that employed with rubber-like organopolysiloxane compositions (this heavy and expensive equipment is described in S, particular in the work by W. LYNCH bearing the title "Handbook of silicone rubber fabrication", pages 43 to 83); light moulding equipment of the type which is used S 20 with plastic materials of low and medium viscosity in the molten state is adequate. During the operation of curing the compositions, the moulds of the presses are in general heated to a temperature above 100°C and below 250°C.

The elastomers obtained with the compositions according to the present invention are perfectly suitable for the desired use, that is to say water treatment.

-I -i day and per person would be sufficient for preventing development of endemic goitre, and about 150 Ag would undoubtedly be sufficient where there is regular consumption 23 The examples which follow illustrate the inventionL EXAMPLE 1: 1.1 Preparation of the elastomer: The following are charged to a kneader: 100 parts of an aw-bis-(dimethylvinylsiloxy) -dimethylpolysiloxane oil having a viscosity of 100,000 mPa.s at 25 0 C and containing 480 ppm (parts per million) of vinyl groupings.

8 parts of a dimethylpolysiloxane oil having a viscosity of 400,000 mPa.s at 0 C and containing 2% by weight of S, vinyl groupings in its chain.

4 parts of an aw-dihydroxydimethylpolysiloxane having a viscosity of m.Pa.s at 25 0

C.

0.3 part of a silane of the formula: CHz=C(CH 3 )COO (CH 2 Si(OCH 3 3 9 parts of precipitated silica having a specific surface area of 170 m 2 /g, commercially available from the company DEGUSSA under the trade name FK 320 DS.

parts of pyrogenic silica of the trade name AEROSIL 300, living a specific surface area of 60 m 2 /g and treated with t t d the active principle. Beyona bus, leMrt x& =cA matrix, and the diffusion flows are greatly diminished. In a surprising and unexpected manner, it has been found that the ri j

I

it

I

-1 24 octamethylcyclotetrasiloxane.

10 parts of crushed quartz (reference

SIFRACO)

0.5 part of Ca(OH) 2 The mixture is subjected to efficient kneading, is heated progressively up to 150 0 C and is then kneaded for one hour at this temperature. After cooling to 30 0

C,

parts of sodium iodide of a particle size of between 100 and 200 microns are introduced and then, after homogenization, 0.6 part of 2,5-bis-(t-butylperoxy)-2,5dimethylhexane is added to the mixture and the whole is kneaded for 5 minutes at this temperature of The composition obtained is then moulded to give an extrudate (or rod) of 9.7 mm diameter, which is then cured for 15 minutes in an oven at 170°C. This uniform rod is then cured further for 4 hours at 200 0 C. The resulting product is an elastomer of cylindrical shape.

1.2 Measurement of the elution kinetics t t I rr t C I Ce It I I I itt Ii C SI I I *It The elastomer containing Nal is cut to the desired length (22 mm) in accordance with the surface/ volume ratio (5 cm which it is desired to attain, and immersed into a vessel containing 250 ml of distilled water which is temperature-controlled at The vessel is equipped with a magnetic stirrer system actuated by a slow rotational movement (100 rpm) to ensure homogeneity of the solution. It is covered by a lid in order to minimize evaporation of the water.

0 44« BJ B O 'D The nature of the iodine compound and its particle size define the diffusion rate v of the active principle across the matrix.

II I A 00 1( 0 44 4444 0f 4 00 4 Oe 0 0- (4 (4 &r I 41 25 1 ml samples are taken daily during the initial elution time, and weekly samples are taken after 15 days of elution.

The concentration of iodine released per day is determined by titration with an iodide-specific electrode: Two millilitres of a solution (KzSO0 ionic buffer) and one millilitre of distilled water are added to one millilitre of sample from the vessel. The electrode is immersed into this solution, and the electrochemical potential of the solution is read off.

A calibration curve, established beforehand with x 10" 5 M/1 (M mole) to 5 x 10 2 M/1 iodide solutions, allows the iodide concentration in mg/l of the solution to be calculated.

The characteristics of the immersed cylinder are: diameter 9.7 mm height 22 mm surface area 9.2 cm 2 volume 1.64 cm 3 S/V 5 cm-1 total mass 2.57 g initial quantity of I (Qo) 0.652 g The results of the elution kinetics are assembled 25 in the table which follows (Table 1). *i i .1 4 i

,'L

100 parts of a diorganopolysiloxane oil (or a mixture of oils), whose viscosity at 25 0 C is less than 300,000 mPa.s, a Q i i: 4i":

I

i pB.

26 TABLE 1 TIME Q cumulative 100*Q/Qo (DAYS) (grams of active ion) 1.00 0.074 11.23 3.00 0.057 8.72 4.00 0.070 10.72 8.00 0.086 13.16 15.00 0.101 15.42 28.00 0.125 19.04 43.00 0.151 23.06 58.00 0.177 27.12 79.00 0.209 31.97 46 6 6 4 4; 4466

I

6s 4 44 I 4' 44 Q cumulative corresponds to the quantity of I equivalent (which we call active ion) eluted at the time t.

Since it is known that 80 mole% of incorporated active ion is eluted according to zero order kinetics as a function of time, it is possible to calculate the theoretical elution time (Te) in accordance with: *6

L

4 i 44L

I

L ItL t~ r are unsubstituted or substituted by halogen atoms and/or cyano groups, the symbol R' having the meaning of the symbols R or representing a hydroxyl radical, an alkoxy i i

I~

:i

X

M%,

27 0.8 x Qo Te (days) daily flux The curve Q/Qo f(t) and also the Te of the example are shown in Figure 1 of the accompanying drawings.

Example 2: The composition according to Example 1 is moulded to obtain a rod of 22.3 mm diameter, which is transformed into an elastomer by the working method described in this Example 1.

A cylinder having the following characteristics: diameter 22.3 mm height 57 mm surface area 47.7 cm 2 volume 22.25 cm 3 S/V 2.14 cm-l total mass 33.7 g initial quantity of I (Qo) 8.55 g is immersed into 500 ml of distilled water temperaturecontrolled at 20 0

C.

The results of the elution kinetics are assembled in Table 2. The curve Q/Qo f(t) and also the Te of the example are reported on the attached Figure 1.

tIj 'ii SIt V, zocnioropnenyi, aicnioropnenyi ana Lrir--.oropnenyi and

I

I

28 TABLE 2 TIME Q curitulative (DAY) (grams of active ion) 1L.00 0.038 0.44 3.00 0.141 1.64 4.00 I0.132 1.54 8.00 0.511 5.95 15.00 0.58-, 6.85 28.00 0.693 8.07 43.00 0.795 9.26 58.00 0.894 I 10.42 79.00 1.028 11.99 4.

4

I-

*4 4 4 4 'Is.

'It.

4 I I 01 4 St 4% 4 4 I 4 4 4 4 a:

Claims (19)

1. silicone composition, containing: A) a diorganopolysiloxane oil having a viscosity of less than 300,000 mPa.s at 250C, B) an inorganic filler, C) an organic peroxide and D) at least one organic and/or inorganic water- soluble, non-toxic iodine compound in a form which is solid or liquid at ambient temperature oi ec 4 Nan m\ec"kO -,r

2. composition according to Claim 1, which contains, by weight, 5 to 130 parts of iodine compound per 100 parts of the oil

3. Composition according to Claim 2 containing 10 to parts by weight of iodine compound per 100 parts of the oil

4. composition according to Claim 1,2 or 3, in which the inorganic filler is a siliceous filler.

Composition according to Claim 4 in which the inorganic filler is pyrogenic silica or precipitated silica.

6. Composition according to any one of the preceding claims, in which the iodine compound -a iodide or iodate of the general formula: Ma+) (I-)a or (I0-3) a in which a is an integer greater Jor equal to I and M is 41 0 -uurganocyclopolysiloxanes, hexaorganodisiloxanes, f hexaorganodisilazanes or diorganocyclopolysiloxanes (French RA 30 a cation of an alkali metal, an alkaline earth metal, a transition metal or a quaternary ammonium of formula (NY 4 whose radicals Y are identical or different and represent a linear or branched C 1 -C 2 0 -alkyl radical or a hydrogen atom.

7. Composition according to any one of claims 1 to 5 in which the iodine compound is NaI, NalO 3 KI, KIO 3 MgI 2 MgI 2 .8H 2 0, Mg(I0 3 2 .4H 2 0, NH 4 I, FeI 2 .4H 2 0, or MnI 2 i

8. Composition according to any one of Claims 1 to 5, in which the iodine compound is calcium iodobehenate.

9. Composition according to any one of Claims 1 to 5, in which the iodine compound is iodinated polyvinylpyrrolidone. Composition according to any one of the preceding claims, which contains by weight: 100 parts of a polysiloxane oil (or a mixture of oils), whose viscosity at 250C is less than 300,000 mPa.s, 5 to 90 parts of an inorganic filler, 0.1 to 6 parts of an organic peroxide, (D 5 to 130 parts, of a water-soluble, non-toxic organic and/or inorganic iodine compound, and 9 w J~~i l t silicon atoms of these oils are preferably methyl, ethyl, vinyl, phenyl or 3,3,3-trifluoopropyl radicals.

By way of concrete examples of these oils, the ~following oils may be mentionedi i• C 31 0 to 20 parts of an antistructuring agent.

11. Composition according to Claim 10 which contains, for each 100 parts by weight of 10 to 90 parts of and 1 to 15 parts of

12. Composition according to Claim 10 or 11 in which the polysiloxane oil has a viscosity of 800 to 250,000 mPa.s at

13. Composition according to any one of the preceding claims, in which the oil is a linear polymer consisting essentially of a succession of units of the formula R 2 SiO, blocked at each end of its chain by units of the formula R 2 R'SiO 0 5 in which the symbols R, which can be identical or different, represent hydrocarbon radicals which have 1 to 8 carbon atoms and are unsubstituted or substituted by halogen atoms and/or cyano groups, and the symbol R' has the same meaning as the symbols R or represents a hydroxy radical, an alkoxy radical having 1 to 4 carbon atoms or a p-methoxyethyl S radical.

14. Composition according to Claim 13, in which the hydrocarbon radicals of 1 to 8 carbon atoms have: alkyl, halogenoalkyl, alkenyl,cycloalkyl, halogenocycloalkyl, aryl, halogenoaryl, or cyanoalkyl radicals.

Composition according to any one of the preceding claims, which has a penetration from 80 to 400 before the in-orporation of the iodine compound.

16. Composition according to any one of the preceding claims, which is pumpable. butylperoxy)-diisopropylbenzene. These peroxides decompose at sometimes different temperatures and rates. They will therefore be selected i ii E :1: 9; ;I, 32

17. Composition according to Claim 1 substantially ar hr~rinhEofor described in ExFap\e

18. Composition according to any one of the preceding claims, which has been cured by heat to give an elastomer.

19. Process for treating water with an iodine compound, which comprises immersing in said water an elastomer as defined in Claim 18 to allow continuous release of a controlled quantity of iodine into the water. I 4r 4 4 444w 44,4 04 44 4 44 4r 44 *s 0 44 4 4 44 t B b i W i~ r- i i i ai i FI i~L: CH 2 C 4(CH 3 )COO(CH 2 3 Si(OCH 3 3 CH 2 Msi(OC 2 CH 2 OCM 3 3 F 4 33 13 n rr 1, i -A m. U, F mA =jI~~4 =J-V disclosed herein or referred to or indic the specification and/or clai is application, individuall o lectively, and any and all combinations a;;nyr ti-o or more of said steos or features. DATED this TWENTY SEVENTH day of JULY 1989 Rhone-Poulenc Chimie by DAVIES COLLISON Patent Attorneys for the applicant(s) e< J