WO2004092251A1

WO2004092251A1 - Method for production of linear polyorganosiloxanes

Info

Publication number: WO2004092251A1
Application number: PCT/FR2004/000791
Authority: WO
Inventors: Gérard Mignani; Thomas Deforth; Jean-Manuel Mas; Jean-Marc Pujol
Original assignee: Rhodia Chimie
Priority date: 2003-04-11
Filing date: 2004-03-30
Publication date: 2004-10-28
Also published as: FR2853656A1

Abstract

The invention relates to silicone oils and a method for the production of linear organopolysiloxanes with a dynamic viscosity greater than 3000 mm2/s, comprising terminal ethylenically-unsaturated groups at the ends of the chain by means of polymerisation and rearrangement of at least one type of monocyclic polysiloxane in the presence of a blocker with a siloxane function and a catalyst at a temperature greater than 100 °C. The method is characterised in that the catalyst is a catalytic system comprising an alkaline mineral salt and a macroheterobicyclic diamine, 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo-[8,8,8]-hexacosane.

Description

PROCESS FOR THE PREPARATION OF POLYORGANOSILOXANES

LINEAR

The field of the present invention relates to the field of silicone oils.

More specifically, the present invention relates to a process for the preparation of linear polyorganosiloxanes, of kinematic viscosity greater than 3000 mm ² / s and comprising terminal ethylenically unsaturated groups at the ends of the chain, by polymerization and rearrangement of monocyclic polysiloxanes, in the presence a siloxane blocker, an alkaline catalyst and a particular accelerator which is a macroheterobicyclic diamine.

The synthesis of these linear polyorganosiloxane oils can be carried out conventionally by polymerization and rearrangement of cyclic polysiloxanes in the presence of a siloxane blocker. This redistribution reaction requires a long implementation time due to the difficulty in opening the siloxane bond of the blocker so that the polymerization can be carried out. For these operations, it is customary to use acidic or basic catalysts.

In any event, the opening polymerization of cyclosiloxane rings using acid catalytic systems is very common and the literature includes numerous studies in which the polymerizations are initiated by strong protonic acids such as H ₂ SO, HCIO or by LEWIS acids.

When the catalyst is alkaline, the reaction scheme follows an anionic type polymerization and most often requires a supply of activation energy, for example by increasing the temperature, since this reaction is not instantaneous.

In order to accelerate the rate of polymerization, various techniques have been proposed. For example, French patent application No. 2 353 589 describes a process in which the bulk polymerization of cyclic siloxanes in the presence of linear polysiloxanes, playing the role of blocker of the polymerization reaction, is accelerated by the presence of a small amount of a catalytic system composed of an alkaline catalyst and a macrocyclic compound mono- or polycyclic chosen from monocyclic polyethers, monocyclic polythioethers, monocyclic and bicyclic polyamines.

However, for this type of process, although the polymerization speed is accelerated, it is difficult to stabilize the viscosity during polymerization as quickly as possible towards a viscosity plateau close to the desired viscosity of the final product. This level corresponds to the polymerization equilibrium between the monocyclic polysiloxane and the blocker of the polymerization reaction and is therefore a criterion. important to the reaction. This type of process therefore has drawbacks for industrial implementation because the necessary stabilization of the viscosity during polymerization to a plateau is slow. Furthermore, improvements are always desirable in economic terms and in terms of industrial operating conditions.

The industries in the technical field under consideration are therefore awaiting a process for obtaining linear polyorganosiloxanes with kinematic viscosity greater than 3000 mm ² / s and comprising ethylenically unsaturated end groups at the ends of the chain, with a process using an alkaline catalytic system allowing rapid polymerization kinetics while being efficient when the speed of obtaining a viscosity plateau during polymerization.

The main objective of the present invention is therefore to propose a process for the preparation of linear polyorganosiloxanes, of kinematic viscosity greater than 3000 mm ² / s and comprising ethylenically unsaturated end groups at the ends of the chain, using an effective catalytic system when at obtaining rapid polymerization kinetics while allowing rapid obtaining of a viscosity plateau during polymerization corresponding to the polymerization equilibrium.

These objectives among others are achieved by the present invention which relates to a process for the preparation of linear organopolysiloxanes with kinematic viscosity greater than 3000 mm ² / s and comprising ethylenically unsaturated end groups at the ends of the chain by polymerization and rearrangement of at least one type of monocyclic polysiloxane in the presence of a blocker having a siloxane function and of a catalyst at a temperature above 100 ° C., the process being characterized in that the catalyst is urr catalytic system consisting of an alkaline mineral salt (I) and a macroheterobicyclic diamine of formula (II):

(II)

The macroheterobicyclic diamine of formula (II) is also known under the chemical name 4,7,13,16,21, 24-Hexaoxa-1, 10-diazabicyclo- [8, 8, 8] -hexacosane or under the common name of Kryptofix ^® 222. The Applicant has therefore discovered by chance that the use of this compound makes it possible not only to accelerate the polymerization reaction but also to accelerate the obtaining of a viscosity plateau during the reaction, this plateau reflecting the polymerization balance between the monocyclic polysiloxane and the blocker. This advantage is not explained in the prior art.

According to a preferred embodiment, the number of moles a of the macroheterobicyclic diamine of formula (II) is chosen so that the molar ratio a / b, b being the number of moles of the alkaline mineral salt (I), is between 0.7 and 1.20 and even more preferably between 1 and 1.15.

By dynamic viscosity is meant in the context of the invention the Newtonian type viscosity, that is to say the dynamic viscosity, measured in a manner known per se at a given temperature, at a sufficiently low shear rate gradient so that the viscosity measured is independent of the speed gradient. The viscosity is measured using a "Brookfield" viscometer according to the indications of standard AFNOR NFT 76 106 of May 1982.

In the catalytic system according to the invention, the alkaline catalyst (I) consists of a salt of an alkali or alkaline earth metal. It is possible in particular to use the silanolates of an alkali metal or the siliconates of an alkali metal such as a potassium siliconate obtained by heating a mixture consisting of hexamethyldisiloxane (M ₂ ), octamethylcyclotetrasiloxane (D4) and d 'hydroxide potassium, hydroxides such as LiOH, NaOH, KOH and CsOH. Other alkali metal salts which are useful according to the invention are described in the work “Chemistry and Technology of Silicones”, published in 1968 by Académie Press, on page 227. It is in particular possible to use derivatives of these metals such as amides and alcoholates. Advantageously, the alkaline catalyst (I) is a potassium siliconate obtained by heating a mixture consisting of hexamethyidisiloxane (M), octamethylcyclotetrasiloxane (D4) and potassium hydroxide.

The implementation of the process is particularly advantageous for the preparation of linear organopolysiloxanes of kinematic viscosity greater than 3000 mm ² / s consisting of siloxyl units of general formula:

(R °) _n SiO _(4. N) / 2 (III) and terminal siloxy units of formula:

Z (R ¹ ) ₂ SiO _1/2 (IV)

formulas in which the various symbols have the following meaning:

- the symbols R ° and R ¹ are identical or different between them and represent a hydrogen atom, an alkyl radical in Cι-C ₁₂ , linear or branched, optionally substituted, an alkenyl radical, a cycloalkyl radical in C ₅ -C ₁₀ , optionally substituted, an aryl radical in Cβ-Ciβ, optionally substituted, an aralkyl radical, optionally substituted and / or an alkaryl radical;

- the symbol n is an integer equal to 1 or 2;

- the symbol Z represents ethylenically unsaturated hydrocarbon groups of 2 to 20 atoms linked to the Si atom of formula (III) by an Si-C bond and may contain one or more O or N heteroatoms.

In the present description, alkyl denotes a saturated, linear or branched hydrocarbon group, preferably Cι-Cι ₂ (such as methyl, ethyl and propyl); alkenyl denotes a linear or branched, preferably C ₂ -C _8, ethylenically unsaturated (S) hydrocarbon group (such as vinyl, allyl and butadienyl); aryl denotes an aromatic, mono- or polycyclic group, preferably C ₆ -C ₁₀ hydrocarbon (such as phenyl or naphthyl); cycloalkyle denotes a saturated, mono- or polycyclic carbocyclic group, preferably C ₃ -C ₈ (such as cyclohexyl); cycloalkenyl denotes a cycloalkyl group having one or more unsaturations, preferably Cβ-Cs (such as cyclohexenyl); aralkyl denotes for example benzyl; alkaryl denotes for example tolyl or xylyl. More generally, alkaryl and aralkyl denote groups in which the aryl and alkyl parts are as defined above.

In the context of the present invention, the monocyclic polysiloxanes, commonly called “cyclosiloxanes”, which can be polymerized have the formula (V):

(V) in which n is an integer greater than or equal to 3 and less than or equal to 9, the radicals R ² are identical or different from each other and represent a hydrogen atom, a C-ι-Cι alkyl radical ₂ , linear or branched, optionally substituted, an alkenyl radical, a C ₅ -C ₁₀ cycloalkyl radical, optionally substituted, a C _δ -C ₁₈ aryl radical, optionally substituted, an aralkyl radical, optionally substituted and / or a radical alkaryl.

By way of illustration, the radicals R ² are chosen from the methyl, vinyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, t-butyl, phenyl, dimethyl-2,3-phenyl, 0-, p-, or m-tolyl and dimethyl-3,4-phenyl.

Preferably, n 'is greater than or equal to 4 and less than or equal to 9. Advantageously, the radicals R ² represent methyl, vinyl, ethyl and / or phenyl groups.

According to a preferred characteristic of the process according to the invention, octamethylcyclotetrasiloxane (D) or a mixture of monocyclic cyclosiloxanes (V) comprising, octamethylcyclotetrasiloxane (D ₄ ) is polymerized in the context of the present invention. By way of illustration, mention may be made, among the monocyclic polysiloxanes useful in the context of the present invention:

- hexamethylcyclotrisoloxane (D ₃ ), octaphenylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane; and

- the compounds [(CH ₃ ) ₂ SiO] ₅ , [(CH ₃ ) ₂ SiO] ₆ , [(CH ₃ ) ₂ SiO3 ₇ , [(CH ₃ ) ₂ Si O ^< ] ₈ , [(CH ₃ ) ₂ SiO] ₉ , [(CH ₃ ) (C ₂ H ₅ ) SiO] ₃ , [(CH ₃ ) (C ₂ H ₅ ) SiO] ₄ , [(CH ₃ ) (C ₂ H ₅ ) Si O] ₅ , [(CH ₃ ) (C ₂ H ₅ ) SiO] 6, [(C ₂ H ₅ ) ₂ SiO] ₃ , [(C ₂ H ₅ ) ₂ SiO] _4l [(C ₂ H ₅ ) ₂ SiO] ₅ , [(C ₆ H ₅ ) ₂ Si O] ₃ , [(C ₂ H ₅ ) (C ₆ H ₅ ) SiO] ₃ , [(C ₂ H ₅ ) (C ₆ H ₅ ) SiO] ₄ , [(C ₂ H ₅ ) (C ₆ H ₅ ) SiO] ₂ [(C ₂ H5) ₂ SiO], [(C ₂ H ₅ ) (C ₆ H ₅ ) SiO] [(C ₂ H ₅ ) ₂ SiOj ₂ .

Other monocyclic polysiloxanes which can be used in the context of the present invention are described in the work "Chemistry and Technology of Silicones", published in 1968 by Académie Press, on page 272.

Preferably, the blocker having a siloxane function is defined by formula (VI):

(VI) in which:

- the symbols R ³ are identical or different from each other and represent a C ₁ -C ₁₂ alkyl radical, linear or branched, optionally substituted, an alkenyl radical, a C ₅ -C ₁₀ cycloalkyl radical, optionally substituted, an aryl radical in C ₆ -Cι ₈ , optionally substituted, an aralkyl radical, optionally substituted and / or an alkaryl radical; and

the symbols Z ² are identical or different from each other and represent ethylenically unsaturated hydrocarbon groups of 2 to 20 atoms linked to the Si atom of formula (VI) by an Si-C bond and which may contain one or more O heteroatoms or N.

In a preferred embodiment, the ethylenically unsaturated hydrocarbon groups are alkenyl or cycloalkenyl groups chosen from vinyl, 3-butenyl, 5-hexenyl, 9-decenyl, 10-undecenyl, 5.9-decadienyl, 6,11-dodecadienyl, cyclopentadienyl and dicyclopentadienyl groups.

According to a preferred characteristic of the process, the blocker (VI) having a siloxane function is tetramethyldivinyldisiloxane.

Other blockers having a siloxane function (V) useful according to the invention are described in the work “Chemistry and Technology of Silicones”, published in 1968 by Académie Press, on page 264.

According to a preferred embodiment of the invention, the method comprises the following steps: a) introducing into a reactor x mole (s) of monocyclic polysiloxane of formula (V) and y mole (s) of a blocker of formula (VI) ); x and y being chosen so that the ratio y / x is between 0.001 and 0.01; b) the mixture is heated and kept at a temperature Ti between 150 and 180 ° C; c) in order to carry out the polymerization, the catalytic system consisting of a quantity of a mole (s) of the macroheterobicyclic diamine of formula (II) is added, with a = 0.05 to 0.25 mmol / mole of monocyclic polysiloxane of formula (V), and of b mole (s) of the alkaline mineral salt (I), a and b being chosen so that the molar ratio a / b is between 0.7 and 1.20, and more preferably between 1 and 1.15; d) when the desired viscosity is reached, the mixture is neutralized by adding an acid solution (VII) after having optionally filtered and the mixture is cooled; e) optionally distilling the mixture in order to remove the molecules of low molecular mass, and f) recovering the residual oil.

According to a particular embodiment of the invention, the alkaline catalyst (l) is a potassium siliconate, prepared by heating a mixture consisting of hexamethyldisiloxane (M ₂ ), octamethylcyclotetrasiloxane (D4) and hydroxide potassium.

Acid solutions (VII) useful according to the invention are, for example solutions comprising acetic acid, formic acid, propionic acid, glycolic acid, valeric acid, butyric acid, caproic acid, caprilic acid, capric acid, octanoic acid, lauric acid, myristic acid, stearic acid, palmitic acid, oleic acid, undecylenic acid, hydrochloric acid, Hl, HBr, HCIO4, H2SO4, HNO3, H3PO4, triflic acid, paratoluene sulfonic acid, silylated esters of triflic acid, Lewis acids, acrylic acids, polyacrylic acids, polymethacrylic acids functionalized organohalosilanes, functionalized organohalosilanes combined with a disilazane, dimethylvinylsilylacetateβ or phosphorus-based compounds such as phosphorus pentoxide, trichloroethyl phosphite, tris (methylsily!) phosphate and phosphoric acid. A dry ice solution can also be considered for the acid solution (VU)

According to another preferred embodiment, the acid solution (VII) is a silylated solution comprising a mixture of phosphoric acid, hexamethyldisiloxane () and octamethylcyclotetrasiloxane (D4).

An additional step can be envisaged, for example, a standard devolatilization step can be added at the end of the process in order to remove volatile compounds of low molecular weight, for example by distillation at 180 ° C. under reduced pressure.

The following examples are given for information only and cannot be considered as limiting the scope and spirit of the invention.

EXAMPLES

Example 1: Preparation of linear pojyorganosiloxanes with kinematic viscosities greater than 3000 mm ² / s.

800 g (2.703 mol) of octamethylcyclotetrasiloxane (D4) and 1.630 g (9 mmol) of tetramethyldivinylsiloxane are introduced at ambient temperature into a 2 liter stirred stainless steel reactor. The mixture is brought to 160 ° C. under an inert atmosphere (nitrogen flow) and when this temperature is reached the catalytic system comprising 0.1052 g of potassium siliconate (catalyst), obtained by heating a mixture consisting of hexamethyldisiloxane ( ₂ ), octamethylcyclotetrasiloxane (D4) and potassium hydroxide, this solution being equivalent to a solution at 15% by weight potassium hydroxide, and a variable amount of co-catalyst. Then, the temperature of the mixture is brought to 170 ° ^C. while controlling the viscosity of the mixture at regular time intervals using a "Brookfield" viscometer as indicated in the AFNOR NFT 76 106 standard of May 1982. measures the time elapsed to reach the maximum viscosity of the mixture as well as the time elapsed to reach a stable level of viscosity. When viscosity stabilization is obtained, the mixture is cooled to a temperature of 25 ° C. and then the usual neutralization operations are carried out (neutralizing agent: a silylated solution comprising a mixture of phosphoric acid, hexamethyldisiloxane (M ₂ ) and octamethylcyclotetrasiloxane (D4)), filtration and devolatilization to remove the monomer in equilibrium with the polymer and light cyclosiloxanes (distillation at 180 ° C under a reduced pressure of 10 mm of mercury). -Ω-Divinylpolydimethylsiloxane oils are obtained, the viscosities of which are between 45,000 and 55,000 mm ² / s. a) results with co-catalyst = Kryptofix ^® 222:

These results show that Kryptofix ^® 222 makes it possible to reduce the time to reach the maximum viscosity, which corresponds to the time when the concentration of open cyclosiloxane is maximum, while reducing the time necessary to obtain a plateau in the viscosity of the reaction mixture, this level reflecting the polymerization balance between the monocyclic polysiloxane and the blocker.

Claims

Process for the preparation of linear organopolysiloxanes with a kinematic viscosity greater than 3000 mm ² / s and comprising ethylenically unsaturated end groups at the ends of the chain by polymerization and rearrangement of at least one type of monocyclic polysiloxane in the presence of a blocker having a siloxane function and of a catalyst at a temperature above 100 ° C, the process being characterized in that the catalyst is a catalytic system consisting of an alkaline mineral salt (I) and a macroheterobicyclic diamine of formula (11) :

(H)

2. Method according to claim 1 characterized in that the molar ratio a / b is between 0.7 and 1.20, and even more preferably between 1 and 1.15, a being the number of moles of the macroheterobicyclic diamine of formula (II) and b being the number of moles of the alkaline mineral salt (I).

3. Method according to one of the preceding claims, in which the linear organopolysiloxanes of kinematic viscosity greater than 3000 mm ² / s comprising siloxy units of general formula:

(R °) _n SiO _(4. _{N) / 2} (III) and terminal siloxy units of formula:

Z (R ¹ ) ₂ SiOι _{/ 2} (IV) formulas in which the various symbols have the following meaning:

- the symbols R ° and R ¹ are identical or different from each other and represent a hydrogen atom, a C1-C12 alkyl radical, linear or branched, optionally substituted, a C5-C10 cycloalkyl radical, optionally substituted, a radical optionally substituted C6-C18 aryl, an optionally substituted aralkyl radical and / or an alkaryl radical; a hydrogen atom, an alkenyl radical, an optionally substituted C5-C10 cycloalkyl radical, an optionally substituted C6-C18 aryl radical, an optionally substituted aralkyl radical and / or an alkaryl radical;

- the symbol n is an integer equal to 1 or 2; and

the symbols Z are identical or different from each other and represent ethylenically unsaturated hydrocarbon groups of 2 to 20 atoms linked to the Si atom of formula (IV) by an Si-C bond and may contain one or more O heteroatoms or NOT.

4. Method according to one of the preceding claims, in which the monocyclic polysiloxane is defined by formula (V):

(V) in which is not an integer greater than or equal to 3 and less than or equal to 9, the radicals R ² are identical or different from each other and represent a hydrogen atom, a Cι-C-ι alkyl radical ₂ , linear or branched, optionally substituted, an alkenyl radical, an optionally substituted C5-C101 cycloalkyl radical, an optionally substituted C ₆ -Cι ₈ aryl radical, an optionally substituted aralkyl radical and / or an alkaryl radical.

5. Method according to one of the preceding claims, in which the blocker having a siloxane function is defined by the formula (V):

(V) in which:

- the symbols R ³ are identical or different from each other and represent an alkyl radical in C1-C12, linear or branched, optionally substituted, an alkenyl radical, a cycloalkyl radical in C5-C10, optionally substituted, an aryl radical in C6-C18 , optionally substituted, an aralkyl radical, optionally substituted and / or an alkaryl radical; and

the symbols Z ² are identical or different from each other and represent ethylenically unsaturated hydrocarbon groups of 2 to 20 atoms linked to the Si atom of formula (IV) by an Si-C bond and which may contain one or more O heteroatoms or N.

6. Method according to claim 4 or 5 characterized in that it comprises the following steps: a) introducing into a reactor x mole (s) of monocyclic polysiloxane (s) of formula (V) and y mole ( s) a blocker of formula (VI); x and y being chosen so that the ratio y / x is between 0.001 and 0.01; b) the mixture is heated and kept at a temperature Ti between 150 and 180 ° C; c) in order to carry out the polymerization, the catalytic system consisting of a quantity of a mole (s) of the macroheterobicyclic diamine of formula (II) is added, with a = 0.05 to 0.25 mmol / mole of monocyclic polysiloxane of formula (V), and of b mole (s) of the alkaline mineral salt (I), a and b being chosen so that the molar ratio a / b is between 0.7 and 1.20, and more preferentially between 1 and 1.15; d) when the desired viscosity is reached, the mixture is neutralized by adding an acid solution (VII) after having optionally filtered and the mixture is cooled; e) optionally distilling the mixture in order to remove the molecules of low molecular mass, and f) recovering the residual oil.

7. Method according to one of the preceding claims wherein the monocyclic polysiloxane (V) is octamethylcyclotetrasiloxane (D ₄ ) or a mixture of monocyclic cyclosiloxanes (V) comprising octamethylcyclotetrasiloxane (D ₄ ).

8 Method according to claim 5 or 6 characterized in that the symbols Z ² of the compound (VI) represent alkenyl or cycloalkenyl groups.

9. Method according to claim 8 characterized in that the alkenyl and cycloalkenyl groups are chosen from vinyl, 3-butenyl, 5-hexenyl, 9-decenyl, 10-undecenyl, 5.9-decadienyl, 6,11-dodecadienyl groups , cyclopentadienyl and dicyclopentadienyl.

10. Method according to one of the preceding claims wherein the alkaline mineral salt (I) is a potassium siliconate obtained by heating a mixture consisting of hexamethyldisiloxane (M ₂ ), octamethylcyclotetrasiloxane (D4) and hydroxide potassium.

11. Method according to one of the preceding claims wherein the acid solution (VII) is a silylated solution comprising a mixture of phosphoric acid, hexamethyldisiloxane (M ₂ ) and octamethylcyclotetrasiloxane (D4).

2. Method according to one of the preceding claims in which the blocker of formula (VI) is tetramethyldivinylsiloxane.