DE1162569A - Process for stabilizing diorganopolysiloxanes - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Class: C 08 g

German class: 39 c-30

Number:
File number:
Registration date:
Display day:

D 35134 IVd / 39 c
January 9, 1961
February 6, 1964

According to a widely used process for the preparation of diorganosiloxane polymers linear diorganosilane hydrolysates and cyclodiorganopolysiloxanes, preferably cyclic trimers, in Heated in the presence of alkali metal catalysts. Alkaline catalysts very easily cause one Rearrangement of siloxane bonds and lead to an equilibrium between linear and cyclic organosiloxanes. However, since cyclic organosiloxanes are generally not reactive their removal from the polymer is mostly desirable. The easiest way to do this is to do this Heating the product in a vacuum or in a convection oven. By removing the volatile However, cyclic organosiloxanes out of equilibrium become cyclic organosiloxanes from linear polymers reproduced, which in turn are also driven out of the mixture. To get the mixture too stabilize so that the slow loss of linear polymer during the separation of the volatile If constituents are avoided, the catalyst must be neutralized.

Several methods are known for neutralizing the catalyst. After one of these procedures various organic phosphorus compounds are used, after another iodine is used. A Another method works with chlorosilanes or HCl, which, however, are only used in large quantities allowed to be sufficient to neutralize the alkaline catalyst without degrading the linear To effect polymers. In a fourth method, small amounts of silica are added. However, the presence of silica in the polymer can lead to the formation of bonds between polymers and silica and thus to the spontaneous hardening known as "tautening" to lead. In addition, the silica can be used to achieve certain properties, such as optical Kind of interfering in the final products. According to another, especially applied in the case of low-viscosity polymers The process is washed with dilute aqueous acid and then with water; this However, the procedure is cumbersome.

It has now been found that diorganopolysiloxanes containing alkali metal catalysts can stabilize by neutralizing these catalysts without using an excess of the neutralizing agent harms if the diorganopolysiloxane with such Amounts of a maximum 3 carbon atoms containing α-chlorohydrin mixes that at least one chlorine per Alkali metal is present, and then the volatile constituents are removed from the mixture by heating.

Process for stabilizing diorganopolysiloxanes

Applicant:

Dow Corning A. G., Basel (Switzerland)

Representative:

L. F. Drissl, lawyer,

Munich 23, Clemensstr. 26th

Named as inventor:

Leonard B. Bruner, Madison, Wis. (V. St. A.)

Claimed priority:

V. St. v. America of February 8, 1960 (No. 7120)

The diorganopolysiloxanes to be stabilized can be any alkali metal catalysts, such as alkali metal hydroxides, such as lithium, potassium, sodium or cesium hydroxide, or salts of these hydroxides with silanols of low molecular weight, such as

KOSi (CHg) ₂ OSi (CHg) ₈ OK or (CHg) ₈ SiONa

contain.
The polymer can have up to 1 mole percent monoorganosiloxanone units and SiO ^ units; however, the content of these polyfunctional units is preferably below 0.1 mol percent. Triorganosiloxane units can also be present in amounts up to 1 mole percent; they are particularly desirable when one of the organic radicals in the triorganosiloxane units is an alkenyl radical.

The organic radicals bonded to the silicon atoms are generally monovalent, optionally halogenated hydrocarbon radicals. Examples include: alkyl radicals such as methyl, ethyl, isopropyl, tert-butyl, 2-ethylhexyl, dodecyl, octadecyl and myricyl, alenyl radicals such as vinyl, allyl, decenyl and hexadienyl, cycloalkyl radicals such as cyclohexyl and Cyclopentyl, cycloalkenyl radicals such as cyclopentenyl, cyclohexenyl and cyclo-i ^ -hexadienyl, aryl radicals such as Phenyl, naphthyl and xenyl, aralkyl radicals such as benzyl, phenylethyl and xylyl and alkaryl radicals such as tolyl and Dimethylphenyl, as well as chloromethyl-S ^ jS-Trifluorpropyl-, 3,3,4,4,5,5,5-heptafluoropentyl-, perchlor-, phenyl-, 3,4-dibromocyclohexyl-, [«, ^, / S-trifluoro-a-chlorocyclobutyl-], α, α, α-Trifhiortolyl-, 2,4-Dibrombenzyl-,

409 507/473

Difluoromonochlorovinyl and 2-iodocyclopenten-3-yl radicals. However, in general, any diorganopolysiloxane containing an alkali metal catalyst can be used are subjected to the method according to the invention.

The α-chlorohydrins which can be used according to the invention belongs to any chlorohydrin with not more than 3 C atoms, in which one Cl atom and one OH group are bound to adjacent carbon atoms, for example

Ethylene chlorohydrin ClCHCH ₈ OH,
Propylene chlorohydrin CH ₃ CHOHCH ₂ Cl,
Grycerin-a-monochlorohydrm
CICH ₂ CHOHCh ₂ OH and
Glycerin-ay-dichlorohydrin C1CH ₂ CHOHCH ₂ C1.

an amount equivalent to about one sodium atom for every 5000 silicon atoms, polymerized to a highly viscous mass with a Williams plasticity of about 1.984 mm, are mixed according to the invention with 10 g of ethylene chlorohydrin for 1 hour at room temperature. The mixture is then heated ^{to 150 °} C. in a forced-air oven for 166 hours. The weight loss is 1.7%, of which at least 0.8% is excess ethylene chlorohydrin.

A sample of the highly viscous mass is heated to 150 ° C. in a convection oven without prior neutralization heated. After 144 hours the weight loss is 69.2%.

Example 2

For the neutralization of the alkali metal catalyst according to the invention at least as much is required «-Chlorhydrin are used that there is one chlorine atom per alkali metal cation. It is well known that this will be the case the catalysts are used in an amount which has a ratio of alkali metal atoms to silicon atoms of at least 1: 200,000, preferably between 1:20,000 and 1: 2000. It means that under favorable conditions only 0.0005 parts by weight of -chlorohydrin per 100 parts of polymer for neutralization of the catalyst are required: However, it is advisable to use a large molar excess of «-Chlorohydrin use, thus complete neutralization of the catalyst within a reasonable Period is guaranteed. Since the -chlorohydrin does not attack the siloxanes, is a fifty-fold or more excess is not harmful; generally will not be more than 1 to 2 parts by weight of -chlorohydrin used per 100 parts of polymer. However, if necessary 10 or more parts by weight of chlorohydrin can be used per 100 parts of polymer.

The -chlorohydrin is thoroughly mixed with the diorganopolysiloxane containing the alkali metal catalyst. The chlorohydrin, optionally dissolved, can be added in a solvent such as acetone, diethyl ether, benzene, toluene, heptane, butanol, dioxane or tetrahydrofuran. If the mixture is not homogeneous, speeds 1 to 4stündiges heating at temperatures up to 250 ⁰ C, if appropriate under pressure, the neutralization without substantial weight loss. After the end of the mixing process between -chlorohydrin and the polymer, the mixture is freed from volatile substances, in particular cyclic organosiloxanes, excess α-chlorohydrin in a manner known per se, ie by heating in a convection oven or in vacuo to 100 to 250 ^{° C.}

The process according to the invention is particularly suitable for stabilizing diorganosuoxane polymers, used in the manufacture of glass laminates where optical clarity is required should be.

example 1

1000 g of 3,3,3-Trffiuorpropylmethylporysiloxan, the process not claimed here with NaOH in 100 parts by weight of a copolymer of 99.858 mole percent dimethylsiloxane and 0.142 mole percent methylvinylsiloxane, the process not claimed here with KOH in an amount that corresponds to one potassium atom per each 5000 silicon atoms is approximately equivalent, has been polymerized to a highly viscous mass with a Williams plasticity of approximately 1.524 mm, are mixed according to the invention with 1 part by weight of ethylene chlorohydrin. The mixture is rolled, heated for 3 hours at 200 ⁰ C, to secure the end of the reaction, and then heated for 24 hours in a convection oven at 250 ⁰ C. The weight loss is 6.18%.

A sample of the highly viscous mass is heated in the same way without prior neutralization. A weight loss of 99.5% occurs after 24 hours at 250 ° C.

Equivalent results are obtained if the mixed polymer of dimethylsiloxane and methylvinylsiloxane units is replaced by a phenylmethylpolysiloxane which, according to the method not claimed here, contains (C ₆ H ₈ ) (CH ^ aSiONa in an amount equivalent to one sodium atom for every 4000 silicon atoms , was polymerized to a highly viscous mass with a Williams plasticity of 2.032 mm.

Equivalent results are also obtained if, according to the invention, instead of ethylene chlorohydrin each 0.25 part by weight of propylene chlorohydrin, 0.50 part by weight of glycerol-a-monochlorohydrin and 1.0 part by weight of glycerine-ay-dichlorohydrin is used will.

Claims (2)

Patent claims: 1. Process for stabilizing diorganopolysiloxanes containing alkali metal catalysts by neutralizing, characterized in that that the diorganopolysiloxane with such amounts of a maximum of 3 carbon atoms having «-chlorohydrin mixes that there is at least one chlorine per alkali metal, and then the volatile constituents are removed from the mixture by heating. 2. The method according to claim 1, characterized in that one carries out the removal of the volatiles at 100 to 25O ⁰ C. «9W7M7M.64 BuadeadrackeniBedbi