AU629235B2 - Solid silicone-based agricultural compositions with biological action - Google Patents

Abstract

Solid compositions having a biological action in agriculture. They comprise a silicone elastomer matrix in which there is distributed an active substance having a biological action in agriculture in water-soluble form. Application in agriculture.

Description

S6292,35 COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION NAME ADDRESS OF APPLICANT: Rhone-Poulenc Agrochimie 14-20 Rue Pierre Baizet Lyon 9e France NAME(S) OF INVENTOR(S): Ghislaine TORRES Hugues PORTE Jean LAFOREST ADDRESS FOR SERVICE: DAVIES COLLISON Patent Attorneys 1 Little Collins Street, Melbourne, 3000.

COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED: Solid silicone-based agricultural compositions with biological action The following statement is a full description of this invention, including the best method of perfonning it known to me/us:-

I

i 14

-CX~

I le The present invention relates to solid silicone-based agricultural compositions with biological action, their preparation and their use for plant treatment.

The treatment of plants and in particular of crops to promote growth often requires the possibility of progressively releasing biologically active materials on or around the plants from a solid support. Many techniques have been proposed which combine a polymeric material with certain active materials, in particular agrochemicals or fertilizers.

I ,10 In fact these techniques have found limited practical applications or have not found sufficient outlets because of several disadvantages, the principal one of which is the difficulty of regulating the liberation kinetics of the active material, and as a consequence definitely to obtain a specific effect for a given content of active material, particularly when the liberation of the active material must take place in a non-liquid medium, in particular a solid S medium, preferably soil, or in a damp gaseous medium, for example ambient air Other disadvantages also lie in the insufficient harmlessness of the polymers towards the plants to be treated and the environment, as well as their cost and their use.

The object of the present invention is to overcome these disadvantages and to provide compositions with progressive biological action which allow the liberation I I 15 7 Ii of active agricultural materials in a non-liquid medium, in particular a solid medium, preferably soil, or in a gaseous medium, in particular ambient air, in a controlled manner and at low cost, and without disadvantages for the plants to be treated and the environment.

More precisely the invention relates to solid agricultural composition for promoting the growth of plants, which comprises a silicone material, which is permeable to water vapour and crosslinked or not crosslinked and dispersed in a homogeneous manner in the said silicone material, a water-soluble active agricultural material which promotes the growth of plants but which is inert towards the crosslinking of the silicone, the silicone material being such that the liberation kinetics of the water-soluble active agricultural material from the silicone material into a non-liquid or damp gaseous medium are approximately of zero order, and the active agricultural material being present in a proportion of 5 to 50 parts by weight per 100 parts by weight of the silicone material.

The invention relates more particularly to compositions of the above type in which the active material is present in the preferred quantity of 15 to parts by weight per 100 parts by weight of the starting organopolysiloxane.

920616.jnsdatUO1O67/89,2

I

44 3 Several groups may be mentioned as silicones which are usable as materials in the compositions according to the invention.

A first group comprises silicone compositions containing a diorganopolysiloxane gum, a reinforcing filler preferably siliceous, and/or an organic peroxide

(B

2 Preferred compositions contain: 100 parts by weight of a diorganopolysiloxane gum S 10 with a viscosity greater than 1 million mPa.s at 4 5 to 130 parts by weight of a reinforcing siliceous filler (B 1 chosen from pyrolysed silicas and precipitated 4 4 o silicas.

Advantageously the gum has the general formula

R

3 -a(R'O)aSiO(R 2 SiO)nSi(OR')aR 3 _a in which the symbols R, which may be identical or different, represent C 1 -Cg hydrocarbon radicals, which may be substituted by halogen atoms or cyano radicals; the symbol R' represents a hydrogen atom or a C 1

-C

4 alkyl radical, the symbol a represents zero or 1, the symbol n represents a number having a value which is sufficient to obtain a viscosity of at least 1 million mPa.s at 25*C, and at least 50% of the number of radicals represented by R are methyl radicals.

Preferably 0.005 to 0.5 mol% of the residues going to make up the gum are chosen from those of formulae

(CH

2 =CH)(R)SiO and (CH 2

=CH)R

2 -a(OR')aSiOo

I

~I-plc" 4 The gum of viscosity at least 1 million mPa.s at and preferably at least 2 million mPa.s at 25°C, is constituted along the length of its chain of R 2 SiO residues, and is terminated at each extremity of its chain with a R 3 a(R'O)aSio0.5 residue; however, the presence, mixed with these residues, of residues of different structure, for example of formula RSiOl.

5 and SiO 2 in the proportion of at the most 2% with respect to the total number of R 2 SiO and R 3 a(R'O)aSiOO.

5 is not excluded.

S 10 The symbol R represents a C 1

-C

8 hydrocarbon radical i o*o which may be substituted by halogen atoms or cyano radicals; i 0 0 it encompasses more specifically: S oo C 1

-C

5 alkyl radicals, which may be substituted by I halogen atoms or cyano radicals, such as the methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, 3,3,3trifluoropropyl, beta-cyanoethyl or gamma-cyanopropyl radicals,

C

2

-C

4 alkenyl radicals such as the vinyl, allyl or 2butenyl radicals, mononuclear C 6

-C

8 aryl radicals, which may be Ssubstituted by halogen atoms, such as the phenyl, chlorophenyl, tolyl or trifluoromethylphenyl radicals.

The CI-C 4 alkyl radicals represented by the symbol include more specifically the methyl, ethyl, propyl, isopropyl, butyl and secondary butyl radicals.

At least 50% in number, preferably at least 70%, of '2 18 the radicals represented by R are methyl radicals.

In addition, vinyl radicals are preferably also present, in appropriate quantities, in the gum they lead to residues of formula CH 2 =CH(R)SiO and

(CH

2

=CH)R

2 -4(R'0)aSi~O.

5 the number of which represents 0.005 to 0.5 mol%, preferably 0.01 to 0.45 mol.%, of the whole of the residues of general formulae R 2 SiO and

R

3 -a(RQ')aSi~O.

5 which enter the composition of the gum As concrete examples of residues constituting the gums there may be cited those of formulae:

(CH

3 2 SiO, CH 3

(CH

2 =CH)SiO, CH 3

(C

6

H

5 )Si0, (C 6

H

5 2 SiO,

CH

3

(C

2

H

5 )SiO, CH 3

CH

2

-CH

2

(CH

3 )SiO, CH 3 (nC 3

H

7 )SiO,

(CH

3 3 SiO 0 5

(CH

3 2

(CH

2 =CH)SiO 0 5

CH

3

(C

6

H

5 2 Si0 0 5 444 C 3

(C

6

H

5

)(CH

2 H)i 0

HOC

3 -i 0 5

CH

3

O(CH

3 2 Si0 0

C

2

H

5 0(CH 3 2 SiQ 0 5 nC 3

H

7

O(CH

3 2 Si0 0 5 and

HO(CH

2 =CH) (CH 3 )SiO 0 5 The gums are sold by silicone manufacturers, 4 otherwise they can easily be manufactured using techniques 4 which are abundantly described in the chemical literature.

In the majority of cases, methylvinyldimethyl- 4,4 polysiloxane gums are used which have, along the length of 0 0 their chain, (CH 3 2 SiO and CH 2

=CH(CH

3 )SiO residues and, at the end of their chain, residues chosen from those of formulae:

(CH

3 2

(CH

2 =CH)SiO 0 5

HO(CH

3

)(CH

2 =CH)SiO 0 5

(CH

3 3 Si0 0 5

C

6

H

5

(CH

3

(CH

2 =CH)Si0 0 5 and HO(CH 3 2 Si0 0 5 6 6 or dimethylpolysiloxane gums terminated at each end of their chain by one of the preceding residues containing a vinyl radical.

They generally have a viscosity of at least 2 million mPa.s at 25 0

C.

The fillers (B 1 which are preferably reinforcing silicas, are used at the rate of 5 to 130 parts of the diorganopolysiloxane gums They are chosen from the pyrolysed silicas and the precipitated silicas. They have a specific surface area, measured according to the BET methods, o of at least 50 m 2 preferably greater than 70 m 2 a mean size of the primary particles which is less than 0.1 im (micrometre) and an apparent density of less than 200 g/1itre.

S 15 These silicas can be incorporated as such, or after having been treated with organosilicon compounds normally employed for this use. Among these compounds are the S. methylpolysiloxanes such as hexamethyldisiloxane and octamethylcyclotetrasiloxane, methylpolysilazanes such as hexamethyldisilazane and hexamethylcyclotrisilazane, chlorosilanes such as dimethyldichlorosilane, trimethylchlorosilane, methylvinyldichlorosilane and dimethylvinylchlorosilane, and alkoxysilanes such as dimethyldimethoxysilane, dimethylvinylethoxysilane and trimethylmethoxysilane. During this treatment, the silicas can increase their starting weight by a factor of up to preferably about 18%.

I

20 The compositions according to the invention, that is to say the silicone compositions of the first group (that is A mixed with the active material C, can be malaxated in the cold as such, and can be extruded in the most varied forms. The forms of silicone composition obtained can be cut to the desired length such that the cut form contains a sufficient equivalent quantity of active material for release over the desired period.

In a surprising manner, it has been discovered that these uncrosslinked silicone compositions have •physical characteristics which are satisfactory for the applications envisaged.

S* Within the scope of the present invention, an 0 Sorganic peroxide (Bz) could be used in addition to (Bj) or in place of It is then necessary to crosslink the elastomeric composition under heat.

SThe organic peroxides (Bz) are used at a rate of 4* 0.1 to 6 parts, preferably 0.2 to 5 parts, per 100 parts Sof the gums They are well known to technicians, and comprise more especially benzoyl peroxide, 2,4-dichloro- "t benzoyl peroxide, dicumyl peroxide, oxy)-2,5-dimethylhexane, t-butyl perbenzoate, t-butylperoxide and isopropyl carbonate, di-t-butyl peroxide and 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane.

These various peroxides decompose at temperatures and speeds which are sometimes different. They are chosen as a function of the required hardening conditions.

21 -i 8 The silicone compositions according to the invention can contain in addition, per 100 parts of gum from 0.1 to 6 parts of a texturizing agent which is an organofluorinated polymer in the form of a powdery solid.

The fluorinated polymers are used at a rate of 0.1 to 6 parts, preferably 0.15 to 5 parts, per 100 parts of diorganopolysiloxane gums These compounds are well known to technicians; they are prepared by polymerization or copolymerization of monomers chosen, for example, from the group of tetrafluoroethylene, chlorotrifluoroethylene, vinylidene fluoride and hexa- S* fluoropropene. They are therefore polymers or copolymers 0 constituted of residues derived from the preceding 000 monomers; thus polytetrafluoroethylenes, the binary copolymers of the polytetrafluoroethylene-beta-fluoropropene type or the vinylidene fluoride-hexafluoropropene ,4 e type and the ternary copolymers of the vinylidene fluoride-hexafluoropropene-tetrafluoroethylene type are usable.

These compounds can be introduced into the compositions of the invention in the form of powders of mean particle diameter less than 100 micrometres, for example of diameter from 25 to 65 micrometres.

Preferably, when crosslinking agents (B 2 are used, up to 90% by weight of the reinforcing silicas can be replaced by semi-reinforcing or packing fillers, 22 9 the particle diameter of which is greater than 0.1 pm, such as ground quartz, calcined clays and diatomaceous earths.

The silicone compositions can contain in addition from 1 to 10 parts of dimethylpolysiloxane oils with silanol extremities, of viscosity at 25"C between 10 and 5000 mPa.s, preferably from 30 to 1000 mPa.s, per 100 parts of gum Their use is above all recommended when the quantities of reinforcing fillers are high.

10 The preparation of compositions according to the Sinvention is carried out using known mechanical means, for example kneading machines, cylinder mixers or screw eo0 i"«o mixers.

4.4a The various constituents are incorporated within these machines in an order which is capable of being any order. It is nevertheless recommended to load the gum S then, in this order, the siliceous fillers (Bi) and the active material optionally the additive and, lastly, the compound and (B 2 The compositions obtained are stable on storage; in addition, they are easily moulded and extruded, which allows very varied forms to be made. Those which contain peroxide (B 2 are crosslinked by heating. The duration of heating obviously varies with the temperature, the pressure and the nature of the crosslinking components.

It is generally of the order of several minutes at about 150-250'C and a few seconds at about 250-350"C.

I

i 23 10 The elastomers thus formed, especially those obtained by moulding, can optionally be subsequently post-heated for a period of at least one hour at a temperature of between 190 and 270'C, with the goal of achieving their crosslinking.

Nevertheless, these elastomers have, from the end of their first crosslinking phase, that is to say before the optional post-heating phase, physical characteristics which are suitable for the envisaged application.

The optionally crosslinked silicone compositions are advantageously in varied solid forms. For a given Spresentation, the quantity of active material and the duration of release is determined.

*I A second group of silicones which are usable 15 according to the invention comprises vulcanizable, preferably hot-vulcanizable silicone compositions containing: a diorganopolysiloxane gum having, per molecule, at least two vinyl groups bonded to the silicon and a viscosity at 25*C of at least 500,000 mPa.s, at least one organohydropolysiloxane having, per molecule, at least three hydrogen atoms bonded to the silicon, a reinforcing filler, and a catalytically effective quantity of a catlyst which is a compound of a metal of the platinum group.

-r I" 11 1 0 0 o i oe c i 00 00# 0000 l l 0;00«I More precisely the present invention relates to a silicone composition containing: 100 parts of a diorganopolysiloxane gum having, per molecule, at least two vinyl groups bonded to the silicon and a viscosity at 25°C of at least 500,000 mPa.s, at least one organohydropolysiloxane having, per molecule, at least 3 hydrogen atoms bonded to the silicon, in such a quantity that the numerical ratio of the .0 hydride functions of to the vinyl groups of is between 0.4 and 5 to 130 parts of a reinforcing filler, preferably siliceous, chosen from pyrolysed silicas and precipitated silicas, and a catalytically effective quantity of a catalyst which is a compound of a metal of the platinum group.

The numerical ratio of the hydride functions of to the vinyl functions of can be very variable.

It is generally between 0.4 and 10, preferably between 1.1 and 4.

*000 0 0 0 I 0 More particularly the diorganopolysiloxane gum S' has the general formula R3-.(R'O).SiO(R 2 SiO),Si(OR'),R 3 -a s in which the symbols R, which may be identical or different, represent C,-C 8 hydrocarbon radicals, which may be substituted by halogen atoms or cyano radicals; the symbol R' represents a hydrogen atom or a CI-C, alkyl radical, the symbol a represents zero or one, the symbol i i 12 n represents a number having a sufficient value to obtain a viscosity of at least 500,000 mPa.s at 25*C, and at least in number of the radicals represented by R are methyl radicals.

Preferably 0.005 to 0.5 mol% of the residues making up the gum are chosen from those of formulae

(CH

2 =CH)(R)SiO and/or (CH 2

=CH)R

2 The gum of viscosity of at least 500,000 mPa.s at preferably of at least 1 million mPa.s at 25"C, is constituted, along the length of its chain, of R 2 SiO residues, and is terminated at each end of its chain by a

R

3 -a(R'O)aSiOo.5 residue; however, the presence, mixed with 0 these residues, of residues of different structure, for +440 example of formula RSiOl.

5 and Si02, in the proportion of at most 2% with respect to the total number of R 2 SiO and R 3 residues is not excluded.

The symbol R represents a C 1

-C

8 hydrocarbon radical which may be substituted by halogen atoms or cyano radicals; it encompasses more specifically:

C

1

-C

5 alkyl radicals, which may be substituted by halogen atoms or cyano radicals, such as the methyl, ethyl, Spropyl, isopropyl, butyl, isobutyl, pentyl, 3,3,3- 0 0 trifluoropropyl, beta-cyanoethyl or gamma-cyanopropyl radicals,

C

2

-C

4 alkenyl radicals such as the vinyl, allyl or 2butenyl radicals,

I

26 13 mononuclear Cs-C, aryl radicals, which may be substituted by halogen atoms, such as the phenyl, chlorophenyl, tolyl or trifluoromethylphenyl radicals.

The C 1

-C

4 alkyl radicals represented by the symbol more specifically concern the methyl, ethyl, propyl, isopropyl, butyl and secondary butyl radicals.

At least 50% in number, preferably at least of the radicals represented by R are methyl radicals.

In addition, vinyl radicals are preferably also present, in appropriate quantities, in the gum they lead to residues of formula CH 2 =CH(R)SiO and

SCH

2 (R'O).SiO0.

5 the number of which represents 0.005 to 0.5 mol%, preferably 0.01 to 0.45 mol%, of the whole of the residues of general formulae R 2 SiO and

R

3 .a(RO')aSiOo0., which enter the composition of the gum As concrete examples of residues constituting the gums there may be cited those of formulae:

(CH

3 2 SiO, CH 3

(CH

2 =CH)SiO, CH 3

(C

6

H

5 SiO, (C 6 H) 2SiO,

CH

3

(C

2 Hs)SiO, CHC 2

-CH

2

(CHC

3 )SiO, CH 3 (nC 3 H7)SiO, (CH 3 3 Si00.

5

(CH

3 2

(CH

2 =CH)SiO 0 5

CH

3

(C

6 Hs) 2 SiO0.s, CH 3

(C

6

H,)(CH

2 =CH)Si 0 0.

5

HO(CH

3 2 SiOo 5 CH30(CH 3 2 SiO 0 5 CzH 5 O (CH 3 2 SiO0.s, nC 3 H70(CH 3 2 Si 00 s and HO(CH 2

=CH)(CH

3 )SiO 0 5 The gums are sold by silicone manufacturers, otherwise they can easily be manufactured using techniques which are abundantly described in the chemical literature.

27 7 14

Q

I*II

I I.

LIr LI L ii In the majority of cases, methylvinyldimethylpolysiloxane gums are used which have, along the length of their chain, (CH 3 2 SiO and CH 2

=CH(CH

3 )SiO residues and, at the end of their chain, residues chosen from those of formulae:

(CH(C)H

2 =CH)SiO 0

HO(CH

3 (CHz=CH) SiO 0 ,s (CH) 3 SiO 0 5 CeH 5

(CH

3

(CH

2 =CH)SiO 0 and HO(CH3),SiO 0 5 or dimethylpolysiloxane gums terminated at each end of their chain by one of the preceding residues containing a vinyl radical.

They generally have a viscosity of at least 2 million mPa.s at o The organohydropolysiloxane has a siloxane residue of mean general formula: (H)(R)dS04-d-c 2 in which R" represents methyl, phenyl and vinyl radicals, at least of these radicals being methyl radicals, c represents any number from 0.01 to 1 inclusive and d represents any number from 0.01 to 2 inclusive.

These organohydropolysiloxanes are chosen from the linear, branched or cyclic polymers constituted of residues chosen from those of formulae:

R"

2 SiO, H(R")SiO, H(R") 2 SiO0.

5 HSiO 1 R"SiO1.

5 SiO 2 and R"Si ,0s.

They can be liquid, gummy or resinous. They contain at least three 3SiH per molecule.

Concrete examples of products which are 28 15 abundantly mentioned in the literature, are described in detail in American Patents US-A-3,220,972, US-A-3,284,406, US-A-3,436,366 and US-A-3,697,473, which are mentioned as references.

The fillers which are preferably reinforcing silicas, are used at a rate of 5 to 130 parts of the diorganopolysiloxane gums They are chosen from the pyrolysed silicas and the precipitated sil',cas. They have a specific surface area, measured according to the BET methods, of at least 50 m 2 preferably greater than 70 m 2 a mean size of the primary particles of less than 4 i 0.01 pm (micrometre) and an apparent density of less than 200 g/litre.

4444 These silicas can be incorporated as such, or 0 15 after having been treated with organosilica compounds normally employed for this use. Among these compounds are the methylpolysiloxanes such as hexamethyldisiloxane and S* octamethylcyclotetrasiloxane, methylpolysilazanes such as hexamethyldisilazane and hexamethylcyclotrisilazane, chlorosilanes such as dimethyldichlorosilane, trimethylchlorosilane, methylvinyldichlorosilane and dimethylvinylchlorosilane, and alkoxysilanes such as dimethyldimethoxysilane, dimethylvinylethoxysilane and trimethylmethoxysilane. During this treatment, the silicas can increase their starting weight by a factor of up to preferably about 18%.

29 7 16 r 4, *4 4- .4l~ H It is desirable to add a catalytically effective quantity of a hydrosilylation catalyst which is a compound of the platinum group, preferably platinum, at a rate of 0.001 to preferably from 0.05 to calculated as the weight of the catalytic metal with respect to the weight of the gum and of the organohydropolysiloxane All the platinum compounds which are abundantly described in the literature as hydrosilylation catalysts are usable, in particular chloroplatinic acid HPtCls, the reaction products of chloroplatinic acid with alcohols, ethers or aldehydes (American Patent US-A-3,220,972) and the reaction products of chloroplatinic acid with vinylpolysiloxanes, which may be treated with an alkaline agent to eliminate, at least partially, the chlorine atoms (American Patents US-A-3,419,593, US-A-3,775,452 and US-A-3,814,730).

Up to 90% by weight of the reinforcing silicas can be replaced by semi-reinforcing or packing fillers, the particle diameter of which is greater than 0.1 pm, such as ground quartz, calcined clays and diatomaceous earths.

The silicone compositions can contain in addition from 1 to 10 parts of dimethylpolysiloxane oils with silanol extremities, of viscosity at 25 0 C between 10 and 5000 mPa.s, preferably from 30 to 1000 mPa.s, per 100 parts of gum Their use is above all recommended when

I

t j. ii 30 7

S.

00 C 000 00099 000 4964 17 the quantities of reinforcing fillers are high.

The preparation of compositions according to the invention is carried out using known mechanical means, for example kneading machines, cylinder mixers or screw mixers.

The various constituents are incorporated within these machines in an order which is capable of being any order. It is, however, recommended to load the gum then, in this order, the siliceous fillers and the 10 active material optionally the additive and, lastly, the compound If the composition must be stored before extrusion and/or moulding, it is desirable to add an effective quantity of an inhibitor of the catalytic action of the platinum, which will disappear on heating during vulcanization of the composition. Thus, in particular, the organic amines, the silazanes, the organic oximes, the diesters of dicarboxylic acids, the acetylenic ketones and the vinylmethylcyclopolysiloxanes can be used as inhibitors (see, in particular, US-A-3,445,420 and US-A-3,989,667). The inhibitor is used at a rate of 0.005 to 5 parts, preferably 0.01 to 3 parts, per 100 parts of constituent The compositions obtained are easily moulded and extruded, which allows very varied forms to be made. They are, in addition, able to harden into elastomers by heating under pressure or in ambient air to temperatures of the order of 100 to 350'C. The duration of heating t 9 4 1r It t C

C

31 18 obviously varies with temperature, pressure and the nature of the crosslinking compounds. It is generally of the order of several minutes at about 150-250°C and a few seconds at about 250-350°C.

The elastomers thus formed, in particular those obtained by moulding, can optionally be subsequently post-heated for a period of at least one hour to a temperature of between 190 and 270 C with the goal of i achieving their crosslinking.

10 Nevertheless, these elastomers have, from the end i of their first crosslinking phase, that is to say before ai I the optional post-heating phase, physical characteristics which are suitable for the envisaged application.

V Thus the compositions according to the invention can be malaxated cold as such and can be extruded and/or moulded and then vulcanized in the most varied forms.

A third aroup of silicones which are usable according to the invention comprises diorganopolysiloxane compositions, which are hardenable into a silicone elastomer by polycondensation reactions, containing: at least one diorganopolysiloxane oil having, at each end of the chain, at least two condensable or hydrolysable groups, or a single hydroxy group, a polycondensation catalyst for the oil, a silane containing at least three condensable or hydrolysable groups, when is an oil with hydroxy ends.

32 19 In that which follows or that which precedes, except where mentioned to the contrary, the percentages and parts are by weight.

The diorganopolysiloxane oils which are usable in the compositions according to the invention are more particularly those corresponding to formula YSi3.,0(SiR20).SiR3-,Y (1) in which: R represents monovalent hydrocarbon radicals, which may 0 10 be identical or different, Y represents hydrolysable or condensable groups, which may be identical or different, or hydroxy groups, n is chosen from 1, 2 and 3 with n 1 when Y is a hydroxy, and x is an integer greater than 1, preferably greater than The viscosity of the oils of formula is s between 50 and 106 mPa.s at 25 0 C. The alkyl radicals having 1 to 8 carbon atoms, such as methyl, ethyl, propyl, butyl, hexyl and octyl, the vinyl radicals and the phenyl radicals may be mentioned as examples of R radicals. The 3,3,3-trifluoropropyl, chlorophenyl and beta-cyanoethyl radicals may be mentioned as examples of substituted R radicals.

In the products of formula which are generally used industrially, at least 60% by number of the R radicals are methyl radicals, the other radicals generally being phenyl and/or vinyl radicals.

I

I 33 20 The amino, acylamino, aminoxy, ketiminoxy, iminoxy, enoxy, alkoxy, alkoxyalkyleneoxy, acyloxy and phosphato groups may be mentioned as examples of Y hydrolysable groups.

The n-butylamino, sec-butylamino and cyclohexylamino groups may be mentioned as examples of Y amino groups, the benzoylamino group may be mentioned as an example of an N-substituted acylamino group, the dimethylaminoxy, diethylaminoxy, dioctylaminoxy and diphenyl- '10 aminoxy groups may be mentioned as examples of aminoxy groups, and those derived from acetophenone-oxime, acetone-oxime, benzophenone-oxime, methyl ethylketoxime, *4 I diisopropylketoxime and chlorocyclohexanone-oxime may be rf mentioned as examples of iminoxy and ketiminoxy Y groups.

The groups having from 1 to 8 carbon atoms such 1 as the methoxy, propoxy, isopropoxy, butoxy, hexyloxy and octyloxy groups may be mentioned as alkoxy Y groups, and the methoxyethyleneoxy group may be mentioned as an alkoxyalkyleneoxy Y group.

The groups having from 1 to 8 carbon atoms such as the formyloxy, acetoxy, propionyloxy and 2-ethylhexanoyloxy groups may be mentioned as acyloxy Y groups.

Those groups derived from dimethyl phosphate, diethyl phosphate and dibutyl phosphate groups may be mentioned as phosphato Y groups.

Hydrogen atoms and halogen atoms, preferably chlorine, may be mentioned as condensable Y groups.

21 When, in formula above, the Y groups are hydroxy groups and n is then equal to 1, it is necessary, in order to prepare polyorganosiloxane elastomers from polymers of formula above, to use, in addition to condensation catalysts, the crosslinking agents indicated above, which are silanes of general formula: (2) in which R has the meanings given above for formula (1) and Y' represents hydrolysable or condensable groups, i0 which may be identical or different, a is equal to 3 or 4.

The examples given for the Y groups are applic- I able to the Y' groups.

It is desirable to use silanes of formula (2) even in the case in which the oil Y is not a hydroxy group.

In this case it is desirable to use Y groups of the oil which are identical to the Y' groups of the silane The alpha-omega dihydroxylated diorganopolysiloxanes of formula are generally oils, the viscosity of which varies from 500 mPa.s at 25'C to 500,000 mPa.s at 25'C, preferably 800 mPa.s to 400,000 at 25"C; these are linear polymers essentially constituted of diorganosiloxyl residues of formula (R 2 SiO). However, the presence of other residues, generally present as impurities, such as RSi0 3 2 RSiO,/ and SiO 4 is not 35 22 excluded in the proportion of at most 1% with respect to the number of diorganosiloxyl residues.

The organic radicals which are bonded to the silicon atoms of the base oils, and which are represented by the symbol R, can be chosen from the alkyl radicals having from 1 to 3 carbon atoms, such as the methyl, i ethyl and n-propyl radicals, the vinyl radical, the i phenyl radical, the 3,3,3-trifluoropropyl radical and the Sbeta-cyanoethyl radical.

1, 0 At least 60% of the whole of the R radicals are I methyl radicals, at most 1% are vinyl radicals.

|i a. As an illustration of residues represented by the iformula R 2 SiO, there may be mentioned those of formulae:

(CH

3 )zSiO; CH 3

(CH

2 =CH)SiO; CH 3

(C

6 Hs)SiO; CF 3 CHzCH 2

(CH

3 )SiO;

NC-CH

2

CH

2

(CH

3 )SiO; NC-CH 2

(C

6

H

s )SiO.

These base oils are, in the great majority, sold by silicone manufacturers. Otherwise the techniques for their manufacture are well known; they are found described, for example, in French Patents FR-A-1,134,005, FR- A-1,198,749 and FR-A-1,226,745.

More particularly the polyacyloxysilanes, the polyalkoxysilanes, the polyketiminoxysilanes and the polyiminoxysilanes may be mentioned as examples of monomeric silanes of formula and in particular the following silanes:

CH

3 Si(OCOCH 3 3

C

2 HsSi(OCOCH 3 3 (CH2=CH)Si(OCOCH 3 3

C

6

H

s Si (OCOCH 3 3; CF 3

CH

2

CH

2 Si (OCOCH 3 3 NC-CHzCHzSi (OCOCH 3 3; 36 i i 23 CHzCISi (OCOCHzCH 3 3; CH 3 Si (ON=C (CH 3

C

2 2OCHzCHzOCH 3

CH

3 Si(ON=CH-CH 3 OCHzCHzOCH 3 The silanes above, associated with alphaomega dihydroxylated polydiorganosiloxanes of formula (1) can be used in monocomponent compositions which are stable when protected from the air.

As examples of monomeric silane of formula (2) which, associated with alpha-omega dihydroxylated polydiorganosiloxanes of formula can advantageously be ,10 used in bicomponent compositions, the polyalkoxysilanes may be mentioned, and in particular those of formulae: Si (OC 2 Hs) 4; Si (O-n-C 3 H7 Si(0-isoC 3

H

7 4 Si(OC 2

HOCH

3

CH

3 Si(OCH 3 CH2=CHSi (OCH 3

CH

3 Si (OC 2 H4OCH 3 3;

CICH

2 Si(OC 2

H

5 3 CH2 CHSi(OC 2 HOCH) 3.

Polyalkoxypolysiloxanes, in which each molecule t contains at least two and preferably three Y' atoms, the other silicon valencies being satisfied by siloxane bonds SiO- and SiR, may be substituted for all or part of the monomeric silanes described above. Ethyl polysilicate may be mentioned as an example of a polymeric crosslinking agent.

Generally from 0.1 to 20 parts by weight of crosslinking agent of formula are used per 100 parts by weight of polymer of formula The polyorganosiloxane compositions of the type described above which are hardenable to an elastomer contain from 0.001 to 10 parts by weight, preferably from 37 II I I I I I I -24p0 o #O@ 0 00 ag0 0,0o0 0*0 0 0 .00 0( 0

I

tt 0 0.05 to 3 parts by weight of condensation catalyst per 100 parts by weight of polysiloxane of formula The condensation catalyst content of the monocomponent compositions is generally much lower than that used in the bicomponent compositions, and is generally between 0.001 and 0.05 parts by weight per 100 parts by weight of polysiloxane of formula The crosslinking agents of formula whether usable for the preparation of monocomponent or bicomponent 10 compositions, are products which are available on the silicone market, in addition their use in compositions which harden at ambient temperature is known, and figures in particular in French Patents FR-A-1,126,411, FR-A-1,179,969, FR-A-1,189,216, FR-1,198,749, FR-A-1,248,826, FR-A-1,314,649, FR-A-1,423,477, FR-A-1,432,799 and FR-A-2,067,636.

The compositions according to the invention can contain in addition reinforcing or semi-reinforcing or packing fillers which are preferably chosen from siliceous fillers, pyrolysed silicas and precipitated silicas. They have a specific surface area, measured according to the BET methods, of at least 50 m 2 preferably greater than 70 m 2 a mean size of the primary particles which is less than 0.1 gm (micrometre) and an apparent density of less than 200 g/litre.

These silicas can be incorporated as such, or after having been treated with organosilicon compounds 38 25 normally employed for this use. Among these compounds are the methylpolysiloxanes such as hexamethyldisiloxane and octamethylcyclotetrasiloxane, methylpolysilazanes such as hexamethyldisilazane and hexamethylcyclotrisilazane, chlorosilanes such as dimethyldichlorosilane, trimethylchlorosilane, methylvinyldichlorosilane and dimethylvinylchlorosilane, and alkoxysilanes such as dimethyldimethoxysilane, dimethylvinylethoxysilane and trimethylmethoxysilane. During this treatment, the silicas can *o10 increase their starting weight by a factor of up to preferably about 18%.

The semi-reinforcing or packing fillers have a particle diameter which is greater than 0.1 pm, and are chosen from ground quartz, calcined clays and diatomaceous earths.

ti t Generally from 0 to 100 parts, preferably from to 50 parts, of filler can be used per 100 parts of oil The bases of silicone compositions defined in a general manner above are well known to those versed in the technique. They are described in detail in the literature, in particular in numerous patents, and most are commercially available.

These compositions crosslink at ambient temperature in the presence of dampness contributed by the humidity of the air and/or contained in the composition.

They are divided into two large families. The first 39 e 26 family comprises mono-component or single package compositions which are stable in storage when protected from the humidity of the air, and harden to an elastomer in the humidity of the air. In this case the condensation catalyst used is a metallic compound, generally a tin, titanium or zirconium compound.

These mono-component compositions are called acid, neutral or basic according to the nature of the condensable or hydrolysable groups.

10 The compositions described in Patents US-At t t S. 3,035,016, US-A-3,077,465, US-A-3,133,891, US-A-3,409,573, US-A-3,438,930, US-A-3,647,917 and US-A-3,886,118 may be mentioned as examples of acid compositions.

The compositions described in Patents US-A- 3,065,194, US-A-3,542,901, US-A-3,689,454, US-A-3,779,986, GB-A-2,052,540, US-A-4,417,042 and EP-A-69,256 may, for Sexample, be used as neutral compositions.

The compositions described in Patents US-A- 3,378,520, US-A-3,364,160, US-A-3,417,047, US-A-3,464,951, US-A-3,742,004 and US-A-3,758,441 may, for example, be Sused as basic compositions.

According to a preferred variant, mono-component compositions which flow, such as those described in Patents US-A-3,922,246, US-A-3,956,280 and US-A-4,143,088 can also be used.

The second family, which is the preferred family within the scope of the present invention, comprises the 40 27 two component or two package compositions generally containing an alpha-omega dihydroxydiorganopolysiloxane oil a silane or a product coming from the partial hydrolysis of this silane, and a catalyst (C) which is a metallic compound, preferably a tin compound, and/or an amine.

Examples of such compositions are described in Patents US-A-3,678,002, US-A-3,888,815, US-A-3,933,729, US-A-4,064,096 and GB-A-2,032,936.

*t.lI0 Among these compositions the bi-component compositions containing the following are more particularly preferred: 100 parts of an alpha-omega-dihydroxydiorganopolysiloxane oil of viscosity from 50 to 300,000 mPa.s, the organic radicals of which are chosen from the methyl, ethyl, vinyl, phenyl and 3,3,3-trifluoropropyl radicals, at least 60% in number being methyl radicals, up to in number being phenyl radicals and at most 2% being vinyl radicals, 0.01 to 1 part (calculated as weight of tin metal) of a catalytic tin compound, 0.5 to 15 parts of a polyalkoxysilane or polyalkoxysiloxane, 0 to 100 parts, preferably 5 to 50 parts, of siliceous inorganic filler.

The tin catalysts are abundantly described in the above literature, and can in particular be a tin salt

I

41 I I I I 28 of a mono- or dicarboxylic acid. These tin carboxylates are described in particular in Noll's work (Chemistry and Technology of Silicones, page 337, Academic Press, 1968, 2nd edition). Dibutyltin naphthenate, octanoate, oleate and butyrate, dibutyltin dilaurate and dibutyltin diacetate may in particular be mentioned.

The reaction product of a tin salt may also be used as catalytic tin compound, in particular that of a tin dicarboxylate with ethyl polysilicate as described in 0iO Patent US-A-3,186,963. The reaction product of a dialkyldialkoxysilane with a tin carboxylate, as described in Patent US-A-3,862,919, can also be used.

The reaction product of an alkyl silicate or an alkyl trialkoxylsilane with dibutyltin diacetate, as described in Belgian Patent BE-A-842,305, can also be used.

4 *4 tI Among the crosslinking agents the alkyl trialkoxysilanes, the alkyl silicates and the alkyl polysilicates in which the organic radicals are alkyl radicals having from 1 to 4 carbon atoms are more particularly preferred.

The alkyl silicates can be chosen from methyl silicate, ethyl silicate, isopropyl silicate and n-propyl silicate, and the polysilicates chosen from the partial hydrolysis products of these silicates; these are polymers constituted of a large proportion of residues of formulae

(R'O)

3 SiOo.

5 R'OSiOi.

5

(R'O)

2 SiO and Si0 2 the symbol R 4 42 29 representing the methyl, ethyl, isopropyl or n-propyl radicals. Their characterization is normally based on their silica content, which is established by analysis of the hydrolysis product of a sample.

In particular, a partially hydrolysed -ethyl silicate sold under the brand "Ethyl Silicate-40 R by Union Carbide Corporation, or a partially hydrolysed propyl silicate, can be used as polysilicate.

The compositions according to the invention can a 0 rl0 be shaped, extruded or in particular moulded in varied forms, then can be hardened at ambient temperature to an elastomer using atmospheric humidity or by the addition of water. A slight heating, to a temperature of 20 to 150 0 C, can accelerate hardening.

In a surprising manner, it has been discovered that these crosslinked silicone compositions have suitable physical characteristics for the applications envisaged.

A fourth group of silicones which are usable according to the invention relates in fact to a polyaddition silicone composition which is hardenable to an elastomer by hydrosilylation reactions, which contains: at least one organopolysiloxane having, per molecule, at least two vinyl groups bonded to the silicon, at least one organopolysiloxane having, per molecule, at least three hydrogen atoms bonded to the -A 1- 30 silicon, a catalytically effective quantity of a catalyst which is a compound of a metal of the platinum group.

In that which follows or that which precedes, except where mentioned to the contrary, the percentages and parts are by weight.

The quantities of and are generally chosen such that the molar ratio of the hydrogen atoms bonded to the silicon in to the vinyl radicals bonded to the silicon in is generally between 0.4 and S.0 preferably between 0.6 and The vinyl groups in and the hydrogen atoms in are generally bonded to different atoms of silicon.

o These compositions crosslink by addition reaction (also called hydrosilylation reaction), catalyzed by a compound of a metal of the platinum group, of a vinyl j group of the organopolysiloxane with a hydride n function of the organopolysiloxane The vinylated organopolysiloxane can be an I 20 organopolysiloxane having siloxyl residues of formula: SY b 1 t"2 1 in which Y is a vinyl group and Z is a monovalent hydrocarbon group having no unfavourable action on the activity of the catalyst. Z is generally chosen from the alkyl groups having from 1 to 8 carbon atoms inclusive, such as the methyl, ethyl, propyl and 3,3,3-trifluoropropyl groups and the aryl groups such as xylyl, tolyl 44 31and phenyl, a is 1 or 2, b is 0, 1 or 2 and a b is between 1 and 3, optionally all the other residues being residues of mean formula: ZcSiO 4-c (2) 2 in which Z has the same meaning as above and c has a value of between 0 and 3.

The organopolysiloxane can be an organohydropolysiloxane containing siloxyl residues of formula: HdeSi4-de (3) 2 in which W is a monovalent hydrocarbon group having no unfavourable action on the activity of the catalyst and corresponding to the same definition as Z, d is 1 or 2, t e is 0, 1 or 2 and d e has a value between 1 and 3, optionally all the other residues being residues of mean formula: I. 120 W SiO (4) 2 in which W has the same meaning as above and g has a value of between 0 and 3. All the limit values of a, b, c, d and g are inclusive.

The organopolysiloxane can be formed only of residues of formula or can contain in addition residues of formula The organopolysiloxane can have a linear, branched, cyclic or net-like structure. The degree of polymerization is 2 or more, and is generally less than 45 r v- 32 5000. In .addition, if the organopolysiloxane is linear it has a viscosity at 25"C which is less than 500,000 mPa.s.

Z is generally chosen from the methyl, ethyl and phenyl radicals, at least 60 mol% of the Z radicals being methyl radicals.

The organopolysiloxanes and are well known and are, for example, described in Patents US-A- 3,220,972, US-A-3,284,406, US-A-3,436,366, US-A-3,697,473 and US-A-4,340,709.

S. Examples of siloxyl residues of formula are Sthe vinyldimethylsiloxyl residue, the vinylphenylmethylsiloxyl residue, the vinylsiloxyl residue and the vinylmethylsiloxyl residue.

Examples of siloxyl residues of formula are the Si04/ 2 dimethylsiloxane, methylphenylsiloxane, diphenylsiloxane, methylsiloxane and phenylsiloxane residues.

Examples of organopolysiloxane are the dimethylpolysiloxanes with dimethylvinylsiloxyl ends, the A methylvinyldimethylpolysiloxane copolymers with trimethylsiloxyl ends, the methylvinyldimethylpolysiloxane copolymers with dimethylvinylsiloxyl ends and the cyclic methylvinylpolysiloxanes.

The organopolysiloxane can be formed only of residues of formula or contain in addition residues of formula I I I; i-- 46 hv 33 The organopolysiloxane can have a linear, branched, cyclic or net-like structure. The degree of polymerization is 2 or more and is generally less than 5,000.

The group W has the same meaning as the group Z above.

Examples of residues of formula are:

H(CH

3 2 SiO 1

HCH

3 Si02/ 2 H(C6H 5 )Si02/2.

The examples of residues of formula are the t 10 same as those given above for the residues of formula Examples of organopolysiloxane are: S" the dimethylpolysiloxanes with hydrodimethylsilyl ends, the dimethylhydromethylpolysiloxane copolymers with trimethylsilyloxyl ends, the dimethylhydromethylpolysiloxane copolymers with hydrodimethylsiloxyl t ends, the hydromethylpolysiloxanes with trimethylsiloxyl ends and the cyclic methylvinylpolysiloxanes.

The ratio of the number of hydrogen atoms bonded to the silicon in organopolysiloxane to the number of groups with an alkenyl unsaturation in organopolysiloxane is between 0.4 and 10, preferably between 0.6 and This ratio can, however, be between 2 and 5, if it is desired to make elastomeric foams.

Organopolysiloxane and/or organopolysiloxane can be diluted in a non-toxic organic solvent which is compatible with silicones.

1 47 34 The net-like organopolysiloxanes and are at present called silicone resins.

The bases of polyaddition silicone compositions can contain only linear organopolysiloxanes and (2) such as, for example, those described in the abovementioned American Patents: US-A-3,220,972, US-A-3,697,473 and US-A-4,340,709, or can contain at the same time branched or net-like organopolysiloxanes and such as, for example, those described in the abovementioned American Patents: US-A-3,284,406 and US-A-3,436,366.

The catalysts are also well known.

c so so Preferably platinum or rhodium compounds are I *used.

In particular the complexes of platinum with an organic product described in American Patents US-A- 3,159,601, US-A-3,159,602 and US-A-3,220,972 and European Patents EP-A-57,459, EP-A-188,978 and EP-A-190,530 and the complexes of platinum with vinylated organopolysiloxane described in American Patents: US-A-3,419,593, US- A-3,715,334, US-A-3,377,432 and US-A-3,814,730 may be S" used.

S 4 4 4 .4r In particular the rhodium complexes described in British Patents GB-A-1,421,136 and GB-A-1,419,769 may be used.

The generally preferred catalyst is platinum.

In this case, the quantity by weight of catalyst calculated as weight of platinum metal, is generally "IV 48 6 35 between 2 and 600 ppm, in general between 5 and 200 ppm based on the total weight of the organopolysiloxanes (A) and The preferred compositions, within the scope of the present invention, are those which contain: 100 parts of a diorganopolysiloxane oil terminated at each end of its chain by a vinyldiorganosiloxyl residue in which the organic radicals bonded to the silicon atoms are chosen from the methyl, ethyl and S 10 phenyl radicals, at least 60 mol% of these radicals being o 0 methyl radicals, of viscosity 100 to 500,000, preferably from 1,000 to 200,000 mPa.s at at least one organohydropolysiloxane chosen from oo4 the liquid linear or net-like homopolymers and copolymers having, per molecule, at least 3 hydrogen atoms bonded to different silicon atoms'and in which the organic radicals bonded to the silicon atoms are chosen from the methyl sa and ethyl radicals and 60% at least of these radicals oo being methyl radicals, the product being used in a a quantity such that the molar ratio of the hydride functions on the vinyl groups is between 1.1 and 4, a catalytically effective quantity of a platinum catalyst.

In a still more preferred manner up to 50% by weight of polymer is replaced by a net-like copolymer containing trimethylsiloxyl, methylvinylsiloxyl and SiO,4/ residues in which 2.5 to 10 mol% of the silicon I -49- FYYnmnl Oa -7.

I

36 atoms carry a vinyl group and in which the molar ratio of the trimethylsiloxyl groups to the Si0 4 group is between and 1.

The compositions according to the invention can contain in addition reinforcing or semi-reinforcing or packing fillers which are preferably chosen from the siliceous fillers.

The reinforcing fillers are chosen from pyrolyzed silicas and precipitated silicas. They have a specific '.ol surface area, measured according to the BET methods, of t at least 50 m 2 preferably greater than 70 m 2 a mean *4Sc size of the primary particles of less than 0.1 micrometre I,*4 and an apparent density of less than 200 g/litre.

These silicas can be incorporated as such, or after having been treated with organosilica compounds normally employed for this use. Among these compounds are the methylpolysiloxanes such as hexamethyldisiloxane and octamethylcyclotetrasiloxane, methylpolysilazanes such as hexamethyldisilazane and hexamethylcyclotrisilazane, chlorosilanes such as dimethyldichlorosilane, trimethylchlorosilane, methylvinyldichlorosilane and dimethylvinylchlorosilane, and alkoxysilanes such as dimethyldimethoxysilane, dimethylvinylethoxysilane and trimethylmethoxysilane. During this treatment, the silicas can increase their starting weight by a factor of up to preferably about 18%.

I

50 1 37 The semi-reinforcing or packing fillers have a particle diameter greater than 0.1 pm, and are chosen preferably from ground quartz, calcined clays and diatomaceous earths.

Generally from 5 to 100 parts, preferably from to 50 parts of filler can be used per 100 parts of the sum of organopolysiloxanes The polyaddition compositions are generally stored in two packages. In fact they crosslink as soon as both these constituents are mixed. If it is wished to retard this crosslinking to obtain good homogenization of S the active material, an inhibitor of the platinum cata- 0 o""o lyst can be added to the composition. These inhibitors 0* 0 are well known. In particular the organic amines, the silazanes, the organic oximes, the diesters of dicarboxylic acids, the acetylenic alcohols, the acetylenic a ketones and the vinylmethylcyclopolysiloxanes (see for example US-A-3,445,420 and US-A-3,989,667) can be used.

The inhibitor is used at a rate of 0.005 to 5 parts, preferably 0.01 to 3 parts, per 100 parts of constituent 0 In order to obtain a good homogenous distribution of the active material, it is in fact desirable that the silicone matrix has a certain viscosity, of the order of 5,000 to 30,000 mPa.s at 25'C, Such a viscosity can be obtained by pre-crosslinking, this pre-crosslinking being stopped at the desired viscosity by addition of a, I 38 inhibitor.- Thus sufficient time is available to homogenize the active material well within the silicone matrix.

Crosslinking is then finished by heating the matrix to a temperature such that the inhibitor no longer has an effect on the catalytic action of the platinum.

The compositions according to the invention can be malaxated in the cold as such, and can be formed, in particular moulded, into varied forms.

The four groups of silicones described above have the same property, that is to say that when they contain an active material in a water-soluble form which is I dispersed in a uniform manner, the compositions obtained can liberate the active material in a controlled manner in a non-liquid medium, in particular a solid medium, or in a damp gaseous medium, in particular humid ambient air, then into the plant to be treated over a long period.

Processes for the manufacture of compositions according to the invention by intimate mixtures of polysiloxane bases with the active material in a watersoluble form, preferably solid, and then manufacture of the filled elastomer, have been described. This latter technique is preferred but any other technique can be used which allows these compositions to be obtained.

A system of controlled liberation in the matrix form (active material dissolved or dispersed in the polymeric matrix) has liberation kinetics which are ~I r vr mu ThljYT7"rrTn'K hOW AOlnrr~ 4 -39 normally governed by Fick's law, that is to say by diffusion kinetics of the order of 1/2 for only 60% by weight of the active material. Above 60% the matrix becomes exhausted and the diffusion flows are strongly reduced.

In a surprising and unexpected manner, it has been found that the silicone matrix system according to the invention liberates the active material following 0 order kinetics and in a continuous manner until 80% by weight or more of the active material is liberated.

The considerable advantage contributed by the oo silicone matrix is therefore that it is very easy to o o o o extrapolate the continuous diffusion of the active 0. material after measurement of the quantity liberated 15 which represents 10 to 15% of the initial material, since it is known that the diffusion kinetics are of the 0 order and that at least 80% of the active material will be liberated according to these kinetics.

The composition according to the invention comprising the silicone material containing the active material in the water-soluble state can be presented in the rigid or more or less elastic solid State. It can be tI it t presented in very varied forms as a function of the II S applications envisaged, in particular of the active material and the form of the plant to be treated, as well as of the problem to be resolved.

I 52 40 It- can, in particular, be presented in the form of a sheet, band or strip which can be, according to a treatment process which is also part of the invention, applied either right next to any part of the plant to be treated, or at a distance from but in the neighbourhood of the latter in a damp gaseous atmosphere, in particular in humid air.

It can also be advantageous to use the composition according to the invention in the form of small sized elements of varied forms such as cubes, rectangular parallelopipeds, cylinders or spheres, the fundamental S parameters of which are the following: S- the nature of the active material, the mean diameter (particle size) g of the particles of the active material in the preferred case in which the latter is a solid, the content t of the active material within the matrix, S the ratio R of the surface to the volume of the element, and in a general manner according to the geometry i t of the system.

The nature of the active material and its particle size define its diffusion speed V through the matrix.

The smaller g is, the slower V is, and vice versa.

-53 41 The larger t is, the higher is the flow of the active material, and vice versa.

The larger R is, the greater is the eluted flow of active material, and vice versa.

Those versed in the technique can, by routine experiments and without difficulty, arrive rapidly at the required result by extrapolating the theoretical elution time which will correspond to the real diffusion time of the active material.

Active agrochemical materials such as fungicides, o bactericides, algicides, molluscicides, insecticides, nematicides, herbicides, growth regulators or even manures or fertilizers may be mentioned as agricultural biologically active materials in the water-soluble form.

These active materials, in order to be usable according to the invention, must be water-soluble by nature or rendered water-soluble by salification or any equivalent a 0 means.

Fungicides such as the tris-0-ethylphosphonates 20 of sodium, calcium or aluminium (fosetyl-aluminium), phosphorous acid salts, in particular the alkali and alkaline-earth salts, growth regulators such as the salts of 2-chloroethylphosphonic acid (ethephon), herbicides such as substituted phenoxyacetic or phenoxypropionic acids such as the 2,4-dichlorophenoxyacetic acids (2,4 D), 2-chloro-4-methylphenoxyacetic acid (MCPA), 2,4-dichlorophenoxy-2-propionic acid 2-chloro-4-methyl-

I

RA 42phenoxy-2-propionic acid (MCPP or mecoprop), and their alkaline, alkaline-earth or amine or alkanol amine salts, the inorganic alkali, alkaline-earth, amine or alkanol amine salts of N(phosphonomethyl)glycine (glyphosate), bipyridyldiylium halides (diquat and paraquat) and insecticides such as aldoxycarb may be mentioned as examples of active agrochemical materials which are water-soluble by nature or are made water-soluble.

The following examples illustrate the compositions according to the invention and their application without this illustration limiting the scope of the o 0 +invention.

S Example 1: Preparation of component A The following constituents are homogenized at ambient temperature in a malaxater: a) Silicone resin (25 parts) comprising (CH 3 3 SiO 0 2 residues (40 mol%), (CH 3

)(CH

2 =CH)SiO2/ 2 residues (6 mol%) and SiO4/2 residues b) A dimethylpolysiloxane oil (75 parts) which is terminated at each of the ends of its chain with a (CH) (CH2=CH)SiO/2 residue, of viscosity 3,500 l mPa.s at c) Platinum metal (40 ppm by weight) supplied by a 0.25% solution of hexachloroplatinic acid prepared by stirring together at ambient temperature hexachloroplatinic acid (0.6 parts), isopropanol -43parts), xylene (55 parts) and 1,1,3,3-tetramethyl-l,3divinyldisiloxane (55 parts).

Preparation of component B The following constituents are homogenized at ambient temperature in a malaxater: d) Hydrogenated liquid silicone resin (45 parts), prepared by hydrolysis of ethyl silicate and

(CH

3 2 HSiCl, in quantities which correspond to one mole of SiO per two moles of (CH 3 2 HSiCl, in solution in toluene. This resin therefore has a theoretical molar ratio of (CH 3 HSiO 1 2 residues of 2, and a real molar ratio of 2.23.

e) Resin a) from part (12.5 parts) f) Vinylated oil b) from part (37.5 parts).

The elastomeric composition is obtained by mixing component A (10 parts) with component B (1 part).

Prenaration of the comnosition of Examnle 1 44 o 4 4 aLes LI I S l &r 4 3* 4 I I I 1 44 Preparation of the composition of Example 1--

K

2

HPO

3 of average particle size between 100 and 160 microns (25 parts) is incorporated in the elastomeric composition (100 parts). The mixture is stirred, under vacuum, for 15 minutes to degas the mixture.

The whole is then poured into a mould which has been preformed to the required dimensions, namely: 1 5 cm w 2.5 cm h 0.4 cm Curing is carried out at 100*C for 1 h 30 min.

44 Experimental protocol for the measurement of the elution kinetics in air: To verify that the active principle thus incorporated into a silicone elastomer can be dispensed into the ambient gaseous medium, we carried out the following test: The matrix is suspended, using a stainless steel boat, in a confined space in which an atmosphere of 100% relative humidity is maintained. Liberation is followed by analysis of the phosphite salt in the aqueous phase (100 ml) contained in the said recipient.

The controlled liberation curve is reported in Figure 1 which is appended.

Example 2: Preparation of the composition Composition: the following ingredients are mixed intimately using a malaxater: A dimethylmethylvinylpolysiloxane gum (100 parts) ij which is terminated at each of its two ends with a trimethylsiloxy residue, and contains in its chain dimethylsiloxy residues (99.8 mol%) and vinylmethylsiloxy residues (0.2 mol%) and has a S_ I viscosity of 10 million mPa.s at -1 A filler (43.5 parts) which is a pyrolysed silica treated with D4 (octamethylcyclotetrasiloxane) with BET specific surface area 300 m 2 /g.

FP--

i 4 4. 4 45 4* 9 4 4r

I~

tl 4 I II I, I *r U: r L C It A linear dimethylpolysiloxane (1 part) which is terminated at its two ends with dimethylhydroxysiloxane groups, of viscosity 50 mPa.s.

Octamethyltetracyclosiloxane (0.2 part).

K

2

HPO

3 of mean particle size between 100 and 160 microns (37.2 parts).

Malaxation is stopped 30 minutes after the end of the introduction of the silica. The homogeneous composition which has just been prepared, and which is called the master 10 mixture (MM) is removed from the malaxater.

The MM is transferred to a cylinder mixer to incorporate, per 100 parts of MM: a linear methylhydrosiloxane (0.43 part), of viscosity 45 mPa.s at 25°C, which is terminated at 15 each end of its chain with a trimethylsiloxy residue and contains in its chain essentially hydrosiloxy residues, a paste of hexachloroplatinic acid (0.6 part) containing 0.18% by weight of platinum metal.

The catelysed composition is easily detached from the cylinders of the mixer.

It is then injected, under a pressure of 5,000 to 20,000 psi, into a mould having the following dimensions: 1 10 cm w 10 cm h 0.4 cm 46 The mould is preheated to 200"C. Crosslinking therefore takes place in a few seconds.

Strips of: 1 5 cm w 2.5 cm h 0.4 cm i are then cut for the in vitro liberation test.

Experimental protocol for measurement of the elution c t kinetics in air i CS Working as in Example 1, with the composition of tit the present example, the liberation curve shown on Figure S 2 in the appendix is obtained.

Example 3: i A silicone strip containing dipotassium phos- 4I :4*15 phite, such as prepared in Example 1, is placed in the form of a collar, at about 3 cm from the soil, around each stem of seven potted tomato plants, variety Marmande, 5 weeks' old. The pots containing the plants are placed in an enclosure at 20*C and 90% relative humidity.

4 20 It is noted that under these conditions there is no water running over the plants. At the end of 15 days the part of the plant situated above the collar is sampled then, after removing the collar, the part surrounded by the collar and the lower part, and dipotassium phosphite is measured in each of the sampled parts, in comparison with untreated control plants.

m i

I

,1;1 :a

-B

47

I'

Analysis by gas phase chomatography shows that active material cannot be detected in the control plants (detection limit 1 mg/kg fresh weight), while in the treated plants the upper part of the plants contains on average 154 mg/kg, the part in contact with the collar contains 2600 mg/kg and the lower part contains on average 678 mg/kg of active material in relation to the weight of the fresh plants.

Example 4: Preparation of the composition: 6* 4k 4 A

I'

4 1 4 Al A 4r A Composition: the following ingredients are intimately mixed using a malaxater: a dimethylmethylvinylpolysiloxane gum (100 parts) which is terminated at each of its two ends by a trimethylsiloxy residue and containing in its chain dimethylsiloxy residues (99.8 mol%) and vinylmethylsiloxy residues (0.2 mol%) and of viscosity 10 million mPa.s at a filler (43.5 parts) which is a pyrolysed silica treated with D4 (octamethylcyclotetrasiloxane) of BET 20 specific surface area 300 m 2 /g a linear dimethylpolysiloxane (1 part) which is terminated at its two ends with dimethylhydroxysiloxane groups of viscosity 50 mPa.s octamethyltetracyclosiloxane (0.2 part) micronized aluminium ethylphosphite (43 parts) i -48- Malaxation is stopped 30 minutes after the end of the introduction of the silica. The homogeneous composition which has just been prepared, and which is called the master mixture (MM) is removed from the malaxater.

The MM is transferred into a cylinder mixer to incorporate, per 100 parts of MM: 2,5-dimethyl-di(2,5-tert-butylperoxy)hexane parts).

The catalysed composition is easily detached from the 10 cylinders of the mixer.

It is then injected, under a pressure of 5,000 to let 'Of 20,000 psi, into a mould having the following dimensions: f 4 t 4 I 1 t 4 ttE.. 1 10 cm w 10 cm h 0.2 cm 1 The mould is preheated to 200°C. Crosslinking I therefore takes place in a few seconds.

S' Strips of: 1 5 cm w 2.5 cm h 0.2 cm S k are then cut for the in vitro liberation test.

Experimental protocol for the measurement of the elution kinetics in air Working as in Example 1, with the composition of the present example, the controlled liberation curve reported in Figure 3 in the appendix is obtained.

1- 61

OC

m o

O

11 e o 4 -49- Examples 5 to 7: Three compositions are prepared in the form of strips as in, respectively, Examples 1, 2 and 4, except that the active material is replaced by K 2

SO

4 of particle size less than 50 microns (43 parts).

The elution kinetics in air, measured as in Example 1 in controlled liberation curves, are reported on Figure 4 in the appendix under the Nos. 4A, 4B and 4C.

Example 8 10 A paste is prepared by malaxation of: °8 an alpha-omega dihydroxymethylpolysiloxane oil parts) of viscosity 15,000 mPa.s at celite (diatomaceous earth) (22.2 parts) n-propyl silicate (2.3 parts) 15 a hydrated paste (0.5 part) (mixture of dimethylpolysiloxane oil and pyrolysed silica containing water.

The mixture is homogenized for 4 hours and then filtered.

To this paste (100 parts) K 2

SO

4 of mean particle size equal to 50 microns (43 parts) is added.

A flowing product is obtained, which is catalysed by the introduction of tin 2-ethylhexanoate (0.5 g).

The whole is then poured into a mould which has been preformed to the required dimensions, namely: 4** 4.

Il 62

_C_

i t* 50 1 5 cm w 2.5 cm h 0.2 cm Crosslinking is carried out for 1 h 30 min.

Experimental protocol for the measurement of the elution 0 0 9r 0 0 f kinetics in air: Working as in Example 1, with the composition of the present example, the controlled liberation curve reported on Figure 4 in the appendix under No. 4D is obtained.

00 I 0 k '1' II~ I 63 63

Claims (36)

1. A solid agricultural composition for promoting the growth of plants, which comprises a silicone material, which is permeable to water vapour and crosslinked or not crosslinked and dispersed in a homogeneous manner in the said silicone material, a water-soluble active agricultural material which promotes the growth of plants but which is inert towards the crosslinking of the silicone, the silicone material being such that the liberation kinetics of the water-soluble active agricultural material from the silicone material into a non-liquid or damp gaseous medium are approximately of zero order, and the active agricultural material being present in a proportion of 5 to 50 parts by weight per 100 parts by weight of the silicone material. o 2. The composition according to claim 1, in which the I: active agricultural material is present in a proportion of 15 to 4.0 parts by weight per 100 parts by weight of the silicone material.

3. The composition according to claim 1 or 2, in which the silicone material is a silicone composition made from (A) a diorganopolysiloxane gum, a reinforcing filler (B 1 and/or an organic peroxide (B 2

4. The composition according to claim 3, in which the filler (Bi) is a reinforcing siliceous filler. The composition according to claim 4, which comprises: 9206ijmdatoo00,478951 I I 52 100 parts by weight of a diorganopolysiloxane gum with a viscosity greater than 1 million mPa.s at 25*C, and 5 to 130 parts by weight of pyrolysed silica and/or precipitated silica.

6. The composition according to any one of claims 3 to in which the gum has the general formula R3_a(R'O)aSiO(R2SiO)nSi(OR')aR3_a in which the symbols R, which may be identical or different, each represent C 1 -Cg hydrocarbon radicals, which may be substituted by halogen 10 atoms or cyano radicals; the symbol R' represents a hydrogen i t Satom or a C 1 -C 4 alkyl radical; a represents zero or 1; n S. represents a number having a value which is sufficient for the gum to have a viscosity of at least 1 million mPa.s at and at least 50% of the radicals represented by R are I 15 methyl radicals.

7. The composition according to claim 6, in which 0.005 to 0.5 mol% of the residues in gum are of formula (CH 2 =CH)(R)SiO or (CH 2 =CH)R 2 -a(OR')aSiOo. 5

8. The composition according to any one of claims 3 to 7, which contains in addition from 0.1 to 6 parts of a texturizing agent which is an organofluorinated polymer in the form of a powder.

9. The composition according to any one of claims 3 to 8, which contains from 0.1 to 6,parts of the organic peroxide (B 2 The composition according to claim 9, in which up to -Ic 53 by weight of the reinforcing silicone filler (B3) is replaced by a semi-reinforcing or packing filler.

11. The composition according to any one of claims 3 to awen 10, hardened into an elastomer by heating.

12. The composition according to claim 1 or 2, in which the silicone material is a hot-vulcanizable silicone composition containing a diorganopolysiloxane gum having, per molecule, at least two vinyl groups bonded to the silicon o and a viscosity at 25*C of at least 500,000 mPa.s, at least one organohydropolysiloxane having, per molecule, at least three hydrogen atoms bonded to the silicon, a .4 reinforcing filler, and a catalytically effective quantity of a catalyst which is a compound of a metal of the platinum group.

13. The composition according to claim 12, in which the filler is a reinforcing siliceous filler.

14. The composition according to claim 12 or 13, which C. 4 comprises: 100 parts by weight of a diorganopolysiloxane gum 4 20 having, per molecule, at least two vinyl groups bonded to the d, silicon and a viscosity at 25"C of at least 500,000 mPa.s, at least one organohydropolysiloxane having, per molecule, at least 3 hydrogen atoms bonded to silicon, in such a quantity that the numerical ratios of the hydride functions of to the vinyl groups of is between 0.4 and 'Y -I i ^~L1~ 54 i 5 to 130 parts by weight of pyrolysed silica and/or precipitated silica, and j a catalytically effective quantity of a catalyst which is a compound of a metal of the platinum group.

15. The composition according to any one of claims 12 to 14, in which the gum has the general formula R 3 a(R'O)aSiO(R 2 SiO)nSi(OR')aR 3 -a in which the symbols R, which may be identical or different, each represent C 1 -Cg hydrocarbon radicals, which may be substituted by halogen atoms or cyano radicals; the symbol R' represents a hydrogen S atom or a C 1 -C 4 alkyl radical; a represents zero or one; n It: represents a number having a sufficient value for the gum to have a viscosity of at least 1 million mPa.s at 25"C; and at least 50% of the radicals represented by R are methyl radicals.

16. The composition according to claim 15, in which 0.005 i t to 0.5 mol% of the residues in gum are of formula (CH 2 =CH)(R)SiO or (CH 2 =CH)R 2 -a(R'O)aSiOo. 5 I 17. The composition according to any one of claims 12 to 16, which contains frm n 0 t 6 parts~ of an organohydropolysiloxane having a siloxane residue of average general formula: (R")dSi4o__ c a d 4-d-c 2 in which R" represents methyl, phenyl or vinyl, at least of these radicals being methyl, c represents a number from S4/4 a ci1 -Q 55 *o n 0 o *o o* o a 0 o o a 0 00 o 04 o f a 0 0 0.01 to 1 inclusive and d represents a number from 0.01 to 2 inclusive.

18. The composition according to any one of claims 12 to 17, in which the organohydropolysiloxanes are chosen from the linear, branched or cyclic polymers consisting of residues of formula: R" 2 SiO, H(R")SiO, H(R") 2 SiOO 0 5 HSiOl. 5 R"SiO 1 Sio 2 R"SiO 0 5 and are added in a quantity such that the numerical ratio of the hydride functions of to the vinyl groups is between 1.1 and 4. 10 19. The composition according to any one of claims 12 to 18, in which the filler is a reinforcing siliceous filler and up to 90% by weight of the reinforcing siliceous filler is replaced by a semi-reinforcing or packing filler. The composition according to any one of claims 12 to 15 19, hardened into an elastomer by heating.

21. The composition according to claim 1 or 2, in which the silicone material is a silicone composition which is hardenable into a silicone elastomer by polycondensation, comprising: at least one diorganopolysiloxane oil having, at each end of the chain, at least two condensable or hydrolysable groups, or a single hydroxy group, a polycondensation catalyst for the oil and a silane containing at least three condensable or hydrolysable groups, when is an oil with hydroxy end groups. 56

22. The composition according to claim 21, in which the diorganopolysiloxane corresponds to the general formula: YnSi3-nO(SiR 2 0)xSiR 3 -nYn (1) in which the symbols R, which may be identical or different, each represent monovalent hydrocarbon radicals, the symbols Y which may be identical or different, each represent hydrolysable or condensable groups, or hydroxy groups, n is 1, 2 or 3 with n 1 when Y is hydroxy, and x is an integer greater than 1, and preferably greater than

23. The composition according to claim 22, in which R is C 1 -C 8 alkyl, vinyl, phenyl or 3,3,3-trifluoropropyl at least 60% of the R radicals being methyl.

24. The composition according to claim 22 or 23 in which Y is amino, acylamino, aminoxy, ketiminoxy, iminoxy, enoxy, alkoxy, alkoxy-alkyleneoxy, acyloxy or a phosphate group. The composition according to any one of claims 21 to 24 in which the diorganopolysiloxane does not contain hydroxy groups and the composition also contains a silane (D) of formula: R4-aSiY'a (2) in which R is a monovalent hydrocarbon radical, Y' represents hydrolysable or condensable groups, which may be identical or different, and a is 3 or 4.

26. The composition according to any one of claims 21 to 25, which is a monocomponent composition.

27. The composition according to any one of claims 21 to I -57 which is a bi-component composition.

28. The composition according to claim 27, which contains: 100 parts by weight of an alpha-omega-dihydroxy- diorganopolysiloxane oil of viscosity from 50 to 300,000 mPa.s, the organic radicals of which are chosen from the methyl, ethyl, vinyl, phenyl and 3,3,3-trifluoropropyl radicals, at least 60% being methyl radicals, up to being phenyl radicals and at most 2% being vinyl radicals, o S 10 0.01 to 1 part (calculated as weight of tin metal) of a catalytic tin compound, 0 0.5 to 15 parts of a polyalkoxysilane or poly- alkoxysiloxane, and 0000 0 to 100 parts, preferably 5 to 50 parts, of a siliceous inorganic filler.

29. The composition according to claim 1 or 2, in which the silicone material is a silicone composition which is o. hardenable into a silicone elastomer by hydrosilylation, 6 OO comprising: at least one organopolysiloxane having, per molecule, 0 A at least two vinyl groups bonded to silicon, 0 0 at least one organopolysiloxane having, per molecule, at least three hydrogen atoms bonded to silicon, and a catalytically effective quantity of a catalyst which is a compound of a metal of the platinum group. The composition according to claim 29, in which the _I r I tt r 58 molar ratio of the hydrogen atoms bonded to silicon in to the vinyl radicals bonded to the silicon in is between 0.4 and

31. The composition according to claim 29 or comprising: A) at least one organopolysiloxane containing siloxyl residues of formula: Ya b S i (1) 2 in which Y is vinyl, Z is a monovalent hydrocarbon group which has no unfavourable action on the activity of the catalyst, a is 1 or 2, b is 0, 1 or 2 and (a b) is 1 to 3, and optionally all the other residues are residues of average formula: cSiO4-c (2) 2 in which Z has the same meaning as above and c has a value from 0 to 3; B) at least one organopolysiloxane containing siloxyl residues of formula: HdW SiO4(3) d e 4-d-e (3) 2 in which W corresponds to the same definition as above for Z, d is 1 or 2, e is 0, 1 or 2 and (d e) is 1 to 3, and optionally all the other residues are residues of average formula: t 1 '4 1 4 I 14 I 44 4 I. 59 WgSiO 4 (4) 2 in which W has the same meaning as above and g has a value from 0 to 3; and a catalytically effective quantity of a platinum compound.

32. The composition according to any one of claims 29 to 31 comprising: 100 parts of a diorganopolysiloxane oil terminated at each end of its chain by a vinyldiorganosiloxyl residue in which the organic radicals bonded to the silicon atoms are r methyl, ethyl or phenyl radicals, at least 60 mol% of these radicals being methyl radicals, of viscosity 100 to 500,000 mPa.s at at least one organohydropolysiloxane chosen from the liquid linear or crosslinked homopolymers and copolymers Shaving, per molecule, at least 3 hydrogen atoms bonded to different silicon atoms and in which the organic radicals bonded to silicon are methyl or ethyl and 60% at least of these radicals are methyl, the product being used in a quantity such that the molar ratio of the hydride functions to the vinyl groups of is between 1.1 and 4, and a catalytically effective quantity of a platinum catalyst.

33. The composition according to claim 32, in which by weight of the polymer is replaced by a crosslinked 60 copolymer containing trimethylsiloxyl, methylvinylsiloxyl and Si0 4 /2 residues in which 2.5 to 10 mol% of the silicon atoms carry a vinyl group, and in which the molar ratio of the trimethylsiloxyl groups to the SiO 4 /2 groups is between and 1.

34. The composition according to any one of claims 29 to 33, which contains in addition from 5 to 100 parts of reinforcing or semi-reinforcing siliceous filler per 100 S. parts of the sum of the organopolysiloxanes 10 35. The composition according to any one of claims 29 to o 34, which has hardened into an elastomer.

36. The composition according to any one of claims 1 to in which theagricultural material is, inherently water- soluble. S 15 37. The composition according to any one of claims 1 to 36, in which thelagricultural material is a fungicide.

38. The composition according to any one of claims 1 to *o c0cva S36, in which the agricultural material is an insecticide.

39. The composition according to any one of claims 1 to 20 36, in which the agricultural material is a herbicide. °o 40. The composition according to any one of claims 1 to 36, in which thekagricultural material is a plant growth regulator.

41. The composition according to any one of claims 1 to 36, in which thekagricultural material is a fertilizer.

42. The composition according to claim 37, in which the 8 c i *zjl I- 61 o ouo oooo 0o v ev*e 09 0004 000 o 0 0a04 o o0o 9 aoe 00 0 0 0 0 0 o0 o 0 0 r kagricultural material is phosphorous acid or one of its inorganic or organic salts.

43. The composition according to claim 37, in which the iagricultural material is aluminium tris-O-ethylphosphonate.

44. The composition according to claim 1 substantially as described in any one of the foregoing Examples. A process for the treatment of a plant with an biloegicall active agricultural material which comprises treating said plant with a composition according to any one 10 of claims 1 to 44.

46. The process according to claim 45, in which the composition is applied to all or part of the plant for sufficient time for the supply of an effective quantity of the active agricultural material. 15 47. The process according to claim 45, in which the composition is placed in the neighbourhood of the plant for sufficient time for the supply of an effective quantity of the active agricultural material.

48. The process according to claim 47, in which the 20 composition and the plant or part of the plant to be treated are in a damp gaseous atmosphere.

49. The process according to claim 47, in which the composition and the plant are in a solid medium such as soil. -62- The process according to claim 45, substantially as hereinbefore described. 63 I rrt,- A disclosed herein or referred to or 1 nd ed in the specification and/or claims is application, individually or ectively, and any and all combinations of an nr Mnr, n-f CMJ cf- 0 ,r F 4- 00 o 0 00>0 0 0.0 0 ~0 0 DATED this TWENTY THIRD day of AUGUST 1989 Rhone-Poulenc Agrochimie by DAVIES COLLISON Patent Attorneys for the applicant(s) 40 0 o 00 o 0 00 I p I p 4 0# 4j p Op I: 'p 'p 4.