DE1224931B - Molding compositions based on organopolysiloxanes and containing metal salts or metal oxides as heat stabilizers, which are heat-curable in combination with organic peroxides or curable by high-energy radiation - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

C08g

German KL: 39 b -22/10

Number:
File number:
Registration date:
Display day:

G 31989 IV c / 39 b

April 5, 1961

September 15, 1966

Organopolysiloxane elastomers can easily be exposed to higher temperatures, however, become brittle if this happens for a long time. For the heat stabilization of in connection with organic Peroxides thermosetting or high-energy radiation curable molding compositions on the On the basis of organopolysiloxanes, ferric oxide has hitherto been added to the molding compounds. It is also already known to use iron octoate or barium zirconate for heat stabilization of the organopolysiloxane elastomers to use.

Organopolysiloxane elastomers which have been heat-stabilized using iron salts now have a characteristic Red color and can no longer be colored by adding other dyes.

It has now been found, unexpectedly, that nickel acetate, nickel octoate, nickel chloride, nickel oxide or tungsten oxide, advantageous heat stabilizers for molding compounds based on organopolysiloxanes represent. When these heat stabilizers are used, no red color unsuitable for some uses occurs, and it does furthermore, an improved heat stability effect is achieved.

The invention thus relates to molding compositions based on organopolysiloxanes, in which 100 parts of organopolysiloxane meet 10 to 200 parts of a filler and the organopolysiloxanes essentially consist of diol, which are thermosetting or high-energy radiation curable metal salts or metal oxides as heat stabilizers in connection with organic peroxides -, mono- and triorganosiloxane units are built up, have ^{a viscosity of at least 100,000 cP at 25 0} C, contain monovalent, optionally halogenated hydrocarbon radicals or cyanoalkyl radicals as organic radicals and have an average of about 1.98 to 2.01 organic radicals per silicon atom and which are characterized in that they contain nickel acetate, nickel octoate, nickel chloride, nickel oxide or tungsten oxide as heat stabilizers.

The heat stabilizers are added in such an amount that for 100 parts of organopolysiloxanes about 0.01 to 3, preferably 0.1 to 2 parts of metal. Tungsten oxide or nickel oxide can be added in an amount such that, per 100 parts of organopolysiloxanes, 0.8 to 20, preferably Hit 0.8 to 8 parts of metal.

The fillers contained in the molding compositions according to the invention can be reinforcing or semi-reinforcing or be normal fillers. The reinforcing fillers, e.g. B. silica affect In combination with organic peroxides, heat-curable or high-energy radiation curable molding compositions containing metal salts or metal oxides as heat stabilizers on the Based on organopolysiloxanes

Applicant:

General Electric Company,

Schenectady, N. Y. (V. St. A.)

Representative:

Dipl.-Ing. M. Licht and Dr. R. Schmidt, Patent Attorneys, Munich 2, Theresienstr. 33

Named as inventor:

William Joseph Bobear, Latham, N. Y. (V. St. A.)

Claimed priority:

V. St. v. America April 11, 1960 (21141) - -

the structure and, depending on their preparation, may contain hydroxyl groups, either in the form of absorbed moisture or moisture bound to the silicon atoms are present. Such fillers can be modified, for example by introducing silicon-bonded fillers Alkoxy groups instead of some hydroxyl groups, which gives certain advantages (e.g. a smaller structure) when added to an organopolysiloxane molding composition.

Sublimated silicon dioxide produced by the combustion of silicon tetrachloride or ethyl silicate in the vapor phase is preferred.

If a reinforcing filler is used, then diphenylsilanediol can be used to reduce the tautness can be added.

Examples of semi-reinforcing fillers or fillers that usually do not affect the structure are: titanium dioxide, lithopone, calcium carbonate, iron oxide or diatomaceous earth.

The organopolysiloxanes contained in the molding compositions according to the invention are known and can same or different silicon-bonded sub-

609 660/446

3 4

contain substituents (e.g. methyl, ethyl, propyl, organopolysiloxane is added.

Vinyl, allyl, phenyl, toluyl, xylyl, benzyl, hydrogen solvents are, for example, turpentine

Phenethyl, naphthyl, chlorophenyl, cyanoethyl oil substitute, toluene, benzene or xylene. Is the added one

or both methyl and phenyl radicals together), metallic compound tungsten oxide or nickel

those through carbon-silicon bonds to the 5 oxide, then an addition in solid form is recommended

Silicon atoms are bonded. with a grain size of 50 μ or less.

They can be in the form of viscous masses or from The heat stabilizer can be the organopolysiloxane

rubber-like, solid substances are present, with you during a corrective process step at

State of the degree of condensation of the starting organic mixing can be added. You can either un-

polysiloxane, the polymerization additive and the like m. IO indirectly into the organopolysiloxane polymer, into the

depends, and they can be given by condensation from a mixture of polymer and filler or,

a liquid organopolysiloxane with about 1.95, if desired, along with the filler

preferably about 1.98 to 2.01 organic residues of polymer are added. It is recommended that the

have been produced per silicon atom. As a poly heat stabilizer before the addition of the hardener dem

merization additives can add the known substances, 15 organopolysiloxane polymer, so that

such as ferric chloride hexahydrate, phenyl-eliminated undesirable side effects and the

phosphoryl chloride or alkaline condensation - best possible results are achieved,

medium, e.g. B. Potassium or sodium hydroxide, present If tungsten oxide or nickel oxide is added,

be. The organopolysiloxane usually consists of then this can during the grinding of the

a polymeric diorganosiloxane which, if desired, organopolysiloxane along with the filler

for example up to 2 mole percent of a mixed poly can be added. Becomes a metal salt in the form of a

merisats from monoorganosiloxane units contain added solution, either as a solution in a solution

e.g. a copolymer of monomethyl hydrocarbons or as an aqueous solution

siloxane and a small percentage (e.g. less also, this solution at the same time with the filling

than 1 mole) of triorganosiloxane units, e.g. to add tri-substance, so that the dispersion of the metallic

methylsiloxy units. Connection within the polymer facilitated

The starting organopolysiloxanes that are used for the her-. Before the curing of the molding compounds made of organic

Position of the polysiloxane and filler in the molding compositions according to the invention should be the excess

existing organopolysiloxanes are used, solvents are removed. By heating

preferably contain organic residues, the excessive and lively circulation of heat in the immediate vicinity

consist predominantly of monovalent, organic residues, the vicinity of the uncured compound can easily be a

by. Carbon-Si bonds to which such excess are withdrawn.

Silicon are bonded and in which almost all siloxane A corresponding hardener can be used during a

units of units with the structural formula R ₂ SiO are added to any process step; it

exist, in which R is preferably a methyl or 35, but in this case an addition after the

Is phenyl. At least 50 to 75% of the total mixing of the organopolysiloxane with the filler

R radicals are preferably methyl radicals. The polystyrene and the metallic connection. Below

Siloxane can be constructed in such a way that any siloxane can be mass molded or molded in the desired manner

Units consist of (CH ₃ ) ₂ Si0, or the siloxane can be used. If the curable organopoly-

If a copolymer of dimethylsiloxane and 40 siloxane molding compound can be formed, then a pressure of

a small amount (e.g. 1 to 20 or more moles - about 7 to 140 kg / cm ² in connection with temperatures

percent) of the units mentioned below or between about 80 and 200 ° C or more

their mixtures be: (C ₆ H ₅ ), (CH ₃ ) SiO and will. Under these conditions the hardening

(C ₆ Hg) ₂ SiO. Also a halogen atom, e.g. B. Chlorine duration depending on the type of hardener, its concentration

atom, can be bound to the phenyl nucleus. 45 and the organopolysiloxane used in each case, the

Are alkenyl residues (e.g. vinyl or allyl residues) the type and concentration of the filler, the intended

intended use and the like by carbon-silicon bonds to the silicon.

bound, then their proportion is preferably A suitable organopolysiloxane molding compound was,

between 0.05 and 2 mole percent of the total number of as described below, prepared and for the

silicon-bonded, organic residues of the organo- 50 embodiments of the invention used,

polysiloxane. 98 parts by weight of octamethylcyclopolysiloxane, 2 parts

For the purpose of hardenability of the molding compounds contain! ^, S ^ -Tetramethyl-1 ^ S ^ -tetravinylcyclotetrasiloxane

these organic peroxides, for example: benzoyl and 0.001 part potassium hydroxide, were mixed with stirring

peroxide, tertiary butyl perbenzoate or bis- (2,4-di- for about 4 hours at a temperature of about

chlorobenzoyl) peroxide. These hardeners can be heated to 55 155 ° C, making a highly viscous, in benzene

in an amount of 0.1 to over 8 percent by weight soluble mass of poor flowability is formed

or more (based on the weight of the organo- was. This substance possessed on average about

polysiloxane) can be used. The molding compounds 1.98 methyl groups and 0.02 vinyl groups per silicon atom

can also be achieved by exposure to high energy and a viscosity of about 6 million cSt.

Electrons are hardened. 60 Tungsten oxide or nickel oxide was used for the

The heat stabilizers can be used in any way as a fine powder with a grain Organopolysiloxane compositions are incorporated. size of less than 50 μ used. Nickel octoate was If the heat stabilizer is in the form of nickel octoate, in the form of a 6% solution of the metal (as octoate) If chloride or acetate is used, then it is recommended to use it in turpentile oil substitute. Nickel acetate or an additive in the form of a solution. The nickel octoate 65 nickel chloride was in the form of a 10- to 35% strength can for example be used in the form of a solution in an aqueous solution. In the execution hydrocarbon added while the examples are the metallic compounds, in Acetate or chloride in an aqueous solution based on the weight units based on metal.

The following exemplary embodiments are given for a more detailed explanation. All information relate to units of weight.

example 1

A mixture of 100 parts of organopolysiloxane obtained in the above manner and 4 parts of diphenylsilanediol was rolled on a two-roll steel, while 0.05 part of nickel was added to the polymer in the form of a 10% strength aqueous solution of nickel acetate. While the nickel salt was being added, 45 parts of sublimed silicon dioxide were gradually added to the resulting organopolysiloxane composition. After thorough mixing, 0.9 parts of a 50 ⁰ / o Benzoylperoxydpaste in dimethylpolysiloxane was added.

Molding Composition According to the Invention in Use: Test strips in the form of ASTM plates were taken from the The resulting mixture was molded at about 132 ° C for 10 minutes and at about 250 ° C for about 24 hours post-hardened. The test strips were subsequently heat aged for an additional 24 hours at 315 ° C. To The same procedure was used to make further sample strips of organopolysiloxane molding compounds with a nickel content of 0.10, 0.50, 1.0 and 2.0 parts in the form of nickel acetate.

Example 2

The procedure of Example 1 was repeated with the difference that nickel octoate in one Turpentine substitute solution containing 6% nickel to which the organopolysiloxane composition was added. That Organopolysiloxane polymer was heated to remove the turpentine oil substitute. After cooling down the hardener was added to the resulting mass and the process of Example 1 continued. Further test strips with 0.15 or 0.30 parts of nickel in the form of nickel octoate were made.

Example 3

According to the procedure of Example 1, test strips were prepared containing nickel in the form of nickel chloride contained. The various samples contained 0.5, 1.0 and 2.0 parts of nickel, respectively.

Example 4

100 parts of the curable organopolysiloxane and. Eight parts of diphenylsilanediol were placed in a batter mixer and a mixture of 40 parts of sublimed silica and 4 parts of tungsten oxide was gradually added. After the mass had been mixed for 1 hour at 110 to 115 ^° C., 2 parts of benzoyl peroxide were added. After the molding composition according to the invention was 24 hours old, test panels were cut from a film which had been formed by rolling. The samples were cured under pressure and for 1 hour at 15O ⁰ C

ίο and post-cured for 24 hours at 25O ⁰ C. Following the procedure of Example 1, test strips were then prepared. Further test strips with 8 parts and 20 parts of tungsten were made. These samples were heat aged for an additional 24 hours at 315 ° C.

Example 5

The procedure of Example 4 was repeated with the difference that 4 parts of nickel oxide were added became. Sample strips heat aged at 315 ° C for 24 hours were made from this Molding compound made.

In addition, comparative samples containing 5 parts of red iron oxide were prepared by the above procedure each contained 100 parts of organopolysiloxane polymer. Comparative samples were also made, which did not contain heat stabilizers. In addition, using ferric octoate as a Heat stabilizer comparative samples prepared according to the method of Example 1. In doing so, one achieved optimum results when 0.015 to 0.03 parts iron for every 100 parts organopolysiloxane.

After the samples of the exemplary embodiments and the comparative samples ^{had been cured under pressure for 24 hours at 250 °} C., measurements were made in accordance with the American Society for Testing Materials in accordance with the provisions Nos. D-314-58 and 412-51T, which the table leading. The hardness (H) in Shore A, the tensile strength in kg / cm ²

(Z) and the extensibility (D) were determined. After the first measurements, the test strips were subjected to a further heat treatment by placing them in an oven at 315 ^° C. for 24 hours. Subsequently, the measurements were repeated so that it could be determined whether the properties of the samples were changed by the heat aging.

The parts by weight of the metallic compounds

in the table below relate to the parts by weight of metal per 100 parts of organopolysiloxane.

additive

Parts 24 hours at 250 Z Hardened ^{0 C.} 24 hours at 315 ° Z C WE rmegealti H 65.6 H test D. 56 - for the 41.6 too brittle 0.02 - 58.0 78 39.8 5 56 77.0 71 41.2 0.10 55 65.3 64 50.6 0.50 55 64.2 60 49.9 1.0 52 71.9 57 59.2 2.0 57 60.4 63 40.6 0.15 43 43.4 58 42.6 0.30 37 76.6 56 37.2 0.5 57 70.4 65 39.2 1.0 56 63.4 62 44.6 2.0 56 71.0 62 44.2 4.0 55 46.9 60 34.3 20.0 57 72 D. 130 310 190 - 180 310 260 360 270 320 230 330 250 300 320 500 170 650 230 340 220 380 270 310 100 30th 250

without

Ferrioctoate ..
Iron oxide ...
Nickel acetate.
Nickel acetate.
Nickel acetate.
Nickel acetate.
Nickel octoate.
Nickel octoate.
Nickel chloride
Nickel chloride
Nickel chloride
Tungsten oxide
Tungsten oxide

The information in the table shows the effectiveness of the predominantly colorless metal compounds in the Molding compositions according to the invention, the hardened molding compositions produced from the organopolysiloxane Give products a significantly improved resistance to heat aging. The samples, according to Example 5 which contained nickel oxide had far better resistance to heat aging compared to samples without such addition. In addition, the metallic connections are in the Molding compositions according to the invention at least as effective as iron oxide and can be used in considerably may be contained in smaller amounts in the molding compounds without a brown discoloration.

Claims (1)

Claim: In connection with organic peroxides, heat-curable or curable by high-energy radiation Molding compositions containing metal salts or metal oxides as heat stabilizers on the 'Basis of organopolysiloxanes where meet 10 to 200 parts of a filler for 100 parts of organopolysiloxane and the organopolysiloxanes are composed essentially of di-, mono- and triorganosiloxane units, one at 25 ° C Have a viscosity of at least 100,000 cP, monovalent, optionally halogenated, organic residues Contain hydrocarbon radicals or cyanoalkyl radicals and on average about 1.98 have up to 2.01 organic radicals per silicon atom, characterized in that the molding compounds as heat stabilizers nickel acetate, nickel octoate, nickel chloride, nickel oxide or tungsten oxide. Considered publications:
German Patent No. 1019 962;
"The Rubber & Plastic Age", July 1957, p. 600 to 608; "Chemistry of Silicones" by Hunyar, 1959, Berlin, p. 88, para. 1, and p. 190, para. 2, and p. 191, para. 1. 609 660/446 9.66 © Bundesdruckerei Berlin