DE1156981B - Organopolysiloxane molding compositions containing boron compounds - Google Patents

Description

GERMAN

PATENT OFFICE

U 5317 IVc / 39 b

REGISTRATION DATE: 29 A P R I L 1958

NOTICE THE REGISTRATION AND ISSUE OF EDITORIAL: NOVEMBER 7, 1963

Organopolysiloxane elastomers have many beneficial properties that make them suitable for many uses. The elastomers adhere to the but generally poor on the metal and also do not have good binding properties when they are placed on top of one another Layers of elastomers. In order to overcome these difficulties, attempts have been made the surface of the metal or material that is brought into contact with the organopolysiloxane is to be treated with a finishing agent or binding agent that adheres to both the metal as well as to the silicone elastomer. This procedure has not always proven to be satisfactory proven.

According to another process, the organopolysiloxanes are partially cured to give elastomers, which by Are sticky in nature and easily adhere to various fabrics. Elastomers made from organopolysiloxane molding compounds, which contain boron compounds, fillers and hardeners are known.

In contrast, contain the molding compositions which are heat-curable to form elastomeric molded parts and which Organopolysiloxanes, reactive boron compounds, monomers and / or low molecular weight containing alkoxy groups polymeric silicon compounds, inorganic fillers and, if appropriate, customary catalysts have, according to the invention as organopolysiloxanes diorganopolysiloxanes.

These compositions can be cured into pressure sensitive adhesive silicone elastomers, all of which have desirable physical and electrical properties of the known silicone elastomers, in addition, after pressure application z. B. on metals, fibers, foils, textiles and others Objects made of natural or synthetic material adhere.

One form of application of the elastomers which can be produced from the compositions according to the invention is production Pressure-sensitive elastic adhesive strip without a backing, which can also be used as an insulating or reinforcing material can be used.

Furthermore, the compositions according to the invention can easily be used as a coating on metals, fibrous materials, foils, Textiles or other objects made of natural or synthetic material are applied and on these are hardened.

The compositions of the invention are suitable for the production of seals, moldings or for Coatings such as wire coatings.

The diorganopolysiloxanes contained in the compositions according to the invention have the following organic substituents:

Organopolysiloxane molding compounds,
which contain boron compounds

Applicant:

Union Carbide Corporation,
New York, NY (V. St. A.)

Representative: Dr.-Ing. F. Wuesthoff, Dipl.-Ing. G. Pulse and Dipl.-Chem. Dr. rer. nat. E. Frhr. v. Pechmann, patent attorneys, Munich 9, Schweigerstr / 2

Claimed priority:
V. St. v. America April 29, 1957

Frank Fekete, Tonawanda, NY (V. St. A.),
has been named as the inventor

a) the same or different types of saturated hydrocarbon radicals, possibly together with

b) identical or different types of olefinically unsaturated hydrocarbon radicals,

c) with identical or different types of halogen-substituted hydrocarbon radicals or

d) with identical or different cyanoalkyl radicals.

So it is z. B. to organopolysiloxanes, the organic substituents of three or more consist of various organic residues of the type described above.

The diorganopolysiloxanes can be partly linear and partly cyclic polysiloxanes, the same or can contain various saturated, optionally halogen-substituted hydrocarbon radicals.

Any olefinically unsaturated hydrocarbon radicals present should preferably be in a limited range Number and are present at a certain distance from one another along the linear polysiloxane chains.

The polysiloxane used in the molding compositions according to the invention is preferably substituted Polysiloxanes, their saturated hydrocarbon radicals

309 747/440

Are methyl, ethyl, amyl and / or phenyl radicals and any unsaturated ones that may be present Residues are vinyl, allyl and / or cyclohexenyl groups, any halogen-substituted groups thereof which may be present Hydrocarbon radicals chlorine- or fluorine- S substituted methyl, propyl, butyl and / or phenyl radicals, including polychloride or polyfluoro substituted ones Are methyl, propyl, butyl and / or phenyl radicals and their optionally present Cyanalkyl radicals / 3-cyanoethyl, y-cyanopropyl and / or (Are 3-cyanobutyl radicals.

Suitable silicon compounds containing alkoxy groups include the organosilanes and proportionally low molecular weight organopolysiloxanes, the alkoxy groups bonded to the silicon in contain a certain, limited number and contain the same or different organic groups one or more silicon atoms via a carbon-silicon bond bound included. The organic substituents can be saturated or unsaturated or halogen-substituted hydrocarbon radicals, aminoalkyl, cyanoalkyl or carbalkoxyalkyl radicals be. One can also use alkoxy-containing silicates.

Preferably, silicon compounds containing alkoxy groups and their organic substituents are used are bound via a carbon-silicon bond. You can use one or more of the contain the following residues:

a) saturated hydrocarbon radicals, namely methyl, ethyl or phenyl radicals,

b) unsaturated hydrocarbon radicals, namely vinyl, allyl or cyclohexenyl radicals,

c) halogen-substituted hydrocarbon radicals, namely chlorine or fluorine-substituted methyl, propyl, Butyl or phenyl radicals including polychloride or polyfluoro-substituted methyl, propyl, Butyl or phenyl groups,

d) cyanoalkyl radicals, namely / 3-cyanoalkyl, y-cyanopropyl, cS-cyanopropyl or e-cyanopentyl radicals,

e) Aminoalkyl radicals, namely y-aminopropyl and <5-aminopentyl radicals, ε-aminopentyl radicals, or

f) Carbalkoxy radicals, namely ß-Carbalkoxyäthyl-, /? - carbalkoxypropyl or ci-carbalkoxypropyl radicals.

The alkoxy groups are preferably methoxy, ethoxy, propoxy or Butoxy groups.

Boron compounds are e.g. B. the boric acids, their alkali or alkaline earth salts and their esters or Metal complexes, boric anhydride, the borohydrides or their complexes, the boron oxides, the saturated ones or unsaturated hydrocarbon borates, the borazoles, the boron halides or the boron anhydrides.

It is preferable to use boron compounds which contain at least one boron atom and at least one Contain oxygen atom. Boron compounds containing only boron, oxygen and hydrogen atoms, are particularly suitable.

The amount of the boron compound can vary within a wide range. You can z. B. of about 0.05 parts by weight and less up to 10 parts by weight and more, based on the organopoly-

40 siloxane, preferably in an amount of about 0.1 to 3 parts by weight per 100 parts by weight of organopolysiloxane, can be used.

The molding compositions according to the invention can contain the usual fillers of the highly reinforcing type, such as carbon black or titanium dioxide, iron oxide, aluminum oxide, diatomaceous earth, calcium carbonate, quartz, finely divided Silicon dioxide with alkoxy groups bonded to the surface, aluminum silicate, zinc oxide, Contain zirconium silicate, barium sulfate-zinc sulfide or iron oxide.

The diorganopolysiloxanes are preferably produced so that

1. The inclusion of substantial amounts of trifunctional ingredients is prevented, in order to achieve a Eliminate crosslinking of linear or cyclic polysiloxane chains by silicon and oxygen atoms and

2. The inclusion of substantial amounts of monofunctional ingredients is avoided those that are intentionally provided to act as terminal groups to control the degree of polymerization to serve. The ratio of organic groups to silicon atoms in the organopolysiloxanes is corresponding about 2.0. A deviation from this value z. B. to about 1.95 to 2.05 is practically lower Meaning.

If the diorganopolysiloxanes contain saturated and unsaturated radicals, they should preferably R (saturated) and R '(unsaturated) siloxane units along the linear polysiloxane chains in Amounts from 0.37 to 0.70 mole percent (corresponding to about 0.05 to 1.0 percent by weight of the total of moles in the linear polysiloxane chains. Polysiloxanes with defined unsaturated hydrocarbon substituents have 0.037 to 0.70% silicon atoms bonded to defined unsaturated hydrocarbon radicals. When hardening this creates around five to twenty crosslinks per molecule.

Crosslinking can also be supported by catalysts, which can be added or replaced some of the unsaturated radicals are used and a crosslinking of, for example, a methyl group to a methyl group or by unsaturated radicals.

If the organopolysiloxanes are organic in addition to the saturated and unsaturated hydrocarbon radicals Substituents, e.g. B. have halogen-substituted hydrocarbon radicals and / or cyanoalkyl radicals, for example, 0.037 to 0.70% of the silicon atoms are preferably olefinically unsaturated hydrocarbon substituents bound.

The diorganopolysiloxanes, the organic substituents of which are halogen-substituted hydrocarbon radicals and hydrocarbon radicals should average about 0.1 to 1, preferably about 0.25 to about Contain 0.75 halogen-substituted hydrocarbon radicals per silicon atom. Are the organic substituents Cyanoalkyl radicals and hydrocarbon radicals should on average be about 0.1 to 1, preferably about 0.25 to 0.75 cyanoalkyl radicals are present per silicon atom.

The silicon compounds containing alkoxy groups are preferably organic

substituted alkoxysilanes or alkoxypolysiloxanes. While the silanes only have a single silicon atom may contain the polysiloxanes, in which the silicon atoms are connected by oxygen atoms, Have 2 to 35 and more silicon atoms per molecule. The latter should preferably be linear and contain no more than about 20 silicon atoms per molecule.

The silicon compounds containing alkoxy groups have at least one, preferably at least two alkoxy groups per molecule. They can also contain up to six or more such groups. Typical alkoxysilanes are: substituted with saturated hydrocarbon or phenyl radicals Alkoxysilanes, the mixed alkoxysilanes substituted with saturated hydrocarbon radicals, which are substituted with unsaturated hydrocarbon radicals substituted alkoxysilanes, the alkoxysilanes with halogen-substituted ones Hydrocarbon radicals, the cyanoalkylalkoxysilanes, the aminoalkylalkoxysilanes, the carbalkoxyalkylalkoxysilanes, the organic silicates, e.g. B. triethyl silicate, and condensed polymers thereof or such silicates as diethoxy-di- (2-ethylhexanediol-1,3) silicate, Diethoxy-di- (triethanolamine) -silicate-N, N-dioleate, diethoxy-o, o-di- (2-ethylhexane-diol, 3) -silicate or diethoxy-o-, o-di- (triethanolamine) -silicate-N, N-dioleate.

The silicon compounds containing alkoxy groups can be used in an amount of, for. B. only 1 up to 100 parts by weight, preferably from about 4 to 80 parts by weight of alkoxy-containing material Use 100 parts by weight of organopolysiloxane.

The component containing alkoxy groups is expediently used in part as a monomeric alkoxysilane and partly as polymeric polysiloxane, namely the alkoxysilane in amounts of about 0.5 to 30 parts by weight, preferably about 1 to 10 parts by weight, based on the organopolysiloxane, and the alkoxy-containing polysiloxane in amounts of 3.5 to about 50 parts by weight, especially in amounts of about 6 to 20 parts by weight.

All organic peroxides commonly used for this purpose are suitable as hardeners.

The compositions according to the invention are prepared by mixing, for. B. on a two-roller mill to the filler, the catalyst, the boron compound and the alkoxy group-containing silicon compound are thoroughly dispersed in the mass.

example 1

In a diorganopolysiloxane, which consists of dimethylsiloxane and ethylvinylsiloxane units, was finely divided silicon dioxide incorporated on a two-roll mill. This crowd was in sixteen Portions divided. 1.2 parts by weight of di-tert-butyl peroxide were added to one portion further the same amount of catalyst and 12 parts by weight of ethoxy-endblocked dimethylpolysiloxane oil, to another the same amount of catalyst and 3.6 parts by weight of ethyltriethoxysilane and the same amount of catalyst and parts by weight of boric acid were added to another. To the rest Servings were an alkoxy-containing silicone and a boron compound in different amounts admitted. The composition of the various masses in parts by weight is given in Table 1.

Table 1

Dimensions

Diorgano-

polysuoxane

filler

catalyst

Boric acid

Ethyl-

triethoxy

silane

Ethoxyendblok-

Cated dimethyl

polysiloxane oil

A. 100 40 1.2 0.0 0.0 B. 100 40 1.2 0.0 0.0 C. 100 40 1.2 0.0 3.6 D. 100 40 1.2 1.5 0.0 E. 100 40 1.2 0.5 1.2 F. 100 40 1.2 0.5 0.0 G 100 40 1.2 0.5 3.6 H 100 40 1.2 0.5 1.2 I. 100 40 1.2 0.5 6.0 J 100 40 1.2 1.0 3.6 K 100 40 1.2 1.0 1.2 L. 100 40 1.2 0.75 3.6 M. 100 40 1.2 0.5 1.2 N 100 40 1.2 0.25 3.6 O 100 40 1.2 1.0 6.0 P. 100 40 1.2 0.75 3.6

0.0 12 * 0.0 0.0 0.0 8.0 * 12.0 * 12.0 * 12.0 * 12.0 * 12.0 * 6.0 * 6.0 * 12 ** 12 ** 12 **

• *) An ethoxy end-blocked ethoxypolysiloxane oil with an average one ethoxy group per terminal silicon atom and an ethoxy group content of 12 to 15 percent by weight.

**) An ethoxy end-blocked dimethylpolysiloxane oil with an average of 1.5 ethoxy groups per terminal silicon atom and with an ethoxy group content of up to 15 percent by weight.

The masses were cured in a mold at 171 ° C. for 20 minutes and at 249 ° C. for 24 hours post-hardened. The physical properties of the molded parts are listed in Table 2.

Table 2

hardness train Decision Tear Lengths Shore strength strength increase Dimensions A. 7o at the kg / cm ² 200 kg / cm Tear 76 64 340 13.5 ° / o A. 68 63.7 210 16.2 0 B. 75 59.5 250 12.8 0 C. 68 56 300 12.6 0 D. 65 61.2 310 18th 10 E. 60 63 300 18.9 10 F. 68 49.7 350 21.2 10 G 71 70 200 20.3 25th H 70 49.3 435 21.7 20th I. 71 40.9 245 15.6 5 J * 70 34.3 375 11.2 50 K * 68 57.4 430 19.6 35 L. 66 70.3 300 27 20th M. 62 51.4 185 20.8 20th N 72 43.4 310 20.3 10 O* 59 60.2 19.3 - · P. 15th

*) Gases are included in the samples.

The addition of small amounts of ferric oxide, for example about 1 or 4 or 5 parts per 100 parts Polysiloxane is used to stabilize the silicone masses during curing and heat aging. For example 3 parts by weight of ferric oxide were mixed with the masses H, I, J, K and these cured.

Table 3

hardness train jjjeiinung Tear Lengths Shore strength strength increase Dimensions* A. ° / o at the kg / cm ² 345 kg / cm Tear 73 70 300 21.2 % H 73 56 330 19.6 20th I. 70 60.5 360 20.1 10 J 75 56 18th 15th K 40

*) With 3 parts by weight of ferric oxide.

The dumbbell-shaped samples used in the tensile strength tests (Table 2) were placed on top of each other after tearing and pressed together by pressure with thumb and forefinger. The torn parts of the masses A and C did not adhere to each other. The torn pieces of the mass D showed little or no tendency to stick together while the torn pieces of the masses E and P strongly adhered to one another. If you look at the narrow ends of the superimposed Parts of samples E tested for tensile strength with P, forces of 3.2 to 8.2 kg had to be applied, to tear the pieces apart.

Example 2

40 parts of finely divided silicon dioxide were added to 100 parts of diorganopolysiloxane according to Example 1. The mixture was divided into thirteen portions, and each was added a boron compound and an alkoxysilane or an alkoxy-containing polysiloxane or both are added.

Table 4

Parts of additives per 100 parts of polysiloxane and 40 parts of silicon dioxide

Dimensions Boron compound Ethyl-
triethoxy
silane Ethoxy
poly-
siloxane *) 1
2 0.5 part of boric acid-2,6-di-
tert-butyl-p-cresyl-di-
allyl ester
0.5 part of boric acid-2,6-di-
tert-butyl-p-cresyl-di-
allyl ester 0
1 12th
0

Dimensions

Boron compound

Ethyl-

triethoxy

silane

Ethoxy

polysiloxane *)

3
4th
5
6th

10
11

12th
13th

0.5 part of boric acid 2,6-di-tert-butyl-p-cresyl-diallyl ester

5.0 parts of boric acid 2,6-di-tert-butyl-p-cresyl-diallyl ester

0.5 part of boric acid 2,6-di-tert-butyl-p-cresyl-di-2-ethylhexyl ester

5.0 parts of boric acid 2,6-di-tert-butyl-p-cresyl-di-2-ethylhexyl ester

0.5 part of boric acid 2,6-di-tert-butyl-p-cresyl-din-butyl ester

5.0 parts of boric acid 2,6-di-tert-butyl-p-cresyl-din-butyl ester

0.5 part of boric acid trin-butyl ester

0.5 part of boric acid amyl ester

0.5 parts boric anhydride

0.5 parts anhydrous
Sodium borate

0.5 part of boric acid tri-o-cresyl ester

1 1 1 1

1 1 1 1 1 1

*) An ethoxy end-blocked dimethylpolysiloxane oil with an average one ethoxy group per terminal silicon atom in which the ethoxy groups are 10 to 12 percent by weight turn off.

*) Note see at the end of Table 4. 1.5 parts by weight of di-ter-butyl peroxide were incorporated into masses 1, 3 and 5 and 7 to 13, while 1.5 parts by weight of dichlorobenzoyl peroxide were added to masses 2, 4 and 6 . The catalyzed with di-tert-butyl-peroxide samples were cured form for 20 minutes at 171 ⁰ C, while the spiked samples were Dichlorbenzoylperoxyd form cured by 15minutiges heating to about 121 ° C.

Physical Properties

hardness
Shore A tensile strenght
kg / cm ² strain
° / o Increase in length
when tearing Tear
strength
kg / cm Form hardened 40 to 55
45 to 55 73.5 to 84
56 to 73.5 400 to 600
300 to 400 0 to 10
0 to 15 Post-cured 24 hours at 249 ⁰ C .. 14.1 to 19.8

For the samples where 5 parts of boron compound
were used showed up after curing
Inclusions.

All hardened and post-hardened samples
adhered after applying pressure. The separation
required force of the pressed pieces
was 2.26 to 6.80 kg.

Example 3

A polysiloxane composed of about 64 percent by weight of dimethylsiloxane units and about 36 percent by weight 3,3,3 - trifluoropropylmethylsiloxane units was made in a two-roll mill with 40 parts finely divided silicon dioxide, 1 part Äthyltriäthoxysilan and 0.5 part boric acid mixed. In the crowd

1.2 parts Peroxydkatalysator then were incorporated and provided with catalyst material form cured for 10 minutes at 121 ⁰ C. The cured elastomer is a silicone rubber that adheres when pressure is applied. A preparation produced in the same way, but without ethyltriethoxysilane and boric acid, does not adhere after curing under the same conditions.

Example 4

Starting from a polysiloxane, consisting of 87.65 percent by weight of dimethylsiloxane units, 0.35 percent by weight of ethylvinylsiloxane units and 12.0 percent by weight of diphenylsiloxane units, a preparation was made by rolling, the 100 parts of polysiloxane, 40 parts of silicon dioxide, 12 parts of an ethoxy-endblocked dimethylpolysiloxane oil containing 12 percent by weight of ethoxy groups and with an average of one ethoxy group per terminal silicon atom, 1 part diphenyl diethoxysilane and contained 0.5 part of boric acid. 0.6 parts of dichlorobenzoyl peroxide were added to the mass incorporated. The catalyzed mass was heated at for 15 minutes Mold hardened at 121 ° C. The cured elastomer was then post cured at 249 ° C for 24 hours. The hardened ones as well as the post-cured substances adhered when pressure was applied.

30 Example 5

Starting from a polysiloxane which consisted of 49.65 percent by weight of dimethylsiloxane units, 0.35 percent by weight of ethylvinylsiloxane units and 50.0 percent by weight of γ-cyanopropylmethylsiloxane units, a preparation was produced by rollers containing 100 parts of polysiloxane, 40 parts of silicon dioxide, 6 parts of ethoxy-containing dimethyl polysiloxane Percent by weight of ethoxy groups, 1 part of diphenyldiethoxysilane, 0.5 part of boric acid and 2 parts of iron oxide. In the mass 0.9 parts Dichlorbenzoylperoxyd been incorporated and provided with catalyst material form cured with 15 minutes of heating to 121 ⁰ C. Part of the cured elastomer was post-cured by heating at 149 ° C for 24 hours. The silicone tapes from the form-hardened and post-hardened samples adhered after the application of pressure. Overlapping bands could be fused to a practically homogeneous mass by heating to 149 ° C.

Example 6

a) Production of the starting products in a known manner. An organopolysiloxane containing linear Polysiloxanes consisting essentially of diphenylsiloxane units (12 percent by weight), methylvinylsiloxane units (0.3 percent by weight) and dimethylsiloxane units (87.7 percent by weight) passed, was made by mixing the appropriate amounts of octaphenylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane and octamethylcyclotetrasiloxane in a suitable reaction vessel. The mixture was stirred thoroughly and with Potassium dimethylsilanolate added as a catalyst in an amount that 40 parts of potassium ions per A million parts of the mix were in place. The contents of the vessel were stirred and left on for about 3 minutes Heated to 150 ° C, causing an equilibrium reaction of the cyclotetrasiloxanes to form a rubbery polysiloxane resulted. After heating, the reaction vessel was allowed to cool left to stand at room temperature overnight. The linear polysiloxane resulted in the hardness test on the miniature pentameter a value of 65 at room temperature.

A polysiloxane oil provided with terminal ethoxy groups, which had on average one ethoxy group per terminal silicon atom of the polysiloxane chains, was prepared by first heating a mixture of 700 g of dimethyltriethoxysilane, 2336 g of octamethylcyclotetrasiloxane and 414 g of octaphenylcyclotetrasiloxane to 80 ° C with stirring. Then 3.5 g of tetramethylammonium hydroxide, dispersed in 50 g of cyclic dimethylsiloxane, were added to the mixture, and the resulting mixture was heated to 85 ° C. for 2 ¹ l for ₂ hours and then at 200 ° C. for 2 ¹ l for _{3 hours.} The reaction mixture is then allowed to cool to room temperature and filtered. The product obtained contained 306 g of the desired ethoxy-terminated polysiloxane oil containing an average of one ethoxy group per terminal silicon atom.

b) Application according to the invention. Starting from the polysiloxane shown above, consisting of Dimethylsiloxane, diphenylsiloxane and methylvinylsiloxane units, 100 parts thereof with 40 parts finely divided silica filler mixed in a two-roll mill. The mass obtained was divided into two portions. One sample (AA) was treated with 1.2 parts of di-tert-butyl peroxide, 12 parts by weight of a dimethylpolysiloxane oil provided with terminal ethoxy groups Example 1 and mixed with 3 parts by weight of boric acid. The other sample (BB) was 1.2 parts Di-tert-butyl peroxide, 1.2 parts by weight of a terminal ethoxy group and dimethyl and diphenyl units containing polysiloxane oil and mixed with 3 parts of boric acid.

This mass was 20 minutes at 160 ° C in the Form hardened and post-hardened for a further 24 hours at 250 ° C. The physical Properties of the hardened samples are summarized in the following table:

Table 5

sample hardness train strain Tear Lengths Shore strength strength increase 55 A. ° / o at the AA kg / cm ² 350 kg / cm Tear BB 62 63.3 375 19.7 Ίο 68 64.7 30.7 10 6ο 5

After curing, the samples were pressure sensitive. Strips of this were placed on top of each other and pressed between thumb and forefinger. It was found that the samples had a strong tendency possessed to cling to one another. Both samples showed excellent properties for application at

309 747/440

lower temperatures, which are likely to be due to the presence of diphenylsiloxane units.

Claims (2)

PATENT CLAIMS: 1. Molding compounds which are heat-curable to form elastomeric moldings and the organopolysiloxanes, reactive boron compounds, monomeric and / or low molecular weight polymers containing alkoxy groups Silicon compounds, inorganic fillers and, if appropriate, customary catalysts and optionally additionally a haloalkylalk- oxysilane, characterized in that they contain diorganopolysiloxanes as organopolysiloxanes. 2. Molding compositions according to claim 1, characterized in that they are used as diorganopolysiloxane contain those which contain unsaturated or halogenated hydrocarbon radicals or cyanoalkyl radicals own. Considered publications:
U.S. Patent Nos. 2,558,560, 2,721,857;
British Patent No. 563 995. © 309 747/440 10.63