DE1138933B - Molding compositions which can be thermally cured to give elastomers and contain diorganopolysiloxanes, boron compounds, customary hardeners and fillers - Google Patents

Description

INTERNAT. KL. C 08 g

GERMAN

PATENT OFFICE

U 6128 IVd / 39b

REGISTRATION DATE: APRIL 14, 1959

NOTICE
THE REGISTRATION
AND ISSUE OF THE
EDITORIAL: OCTOBER 31, 1962

Silicone elastomers have many favorable properties that make them suitable for many purposes appear. For example, they are resistant to elevated temperatures and can be used as insulating material for electrical conductors or as protective coatings for metals. the Elastomers generally adhere poorly to the substrate and also do not have good binding properties between superposed layers of elastomers.

Elastomer molded parts or coatings made from organopolysiloxanes, boron compounds, fillers and curing agents are known.

In contrast, the molding compositions which are heat-curable to give elastomers contain diorganopolysiloxanes, Contain boron compounds, customary hardeners and fillers, according to the invention additionally at least a hydroxyl-containing silane or a hydroxyl-containing polysiloxane and at least one alkoxy group-containing silane and / or alkoxy group-containing polysiloxane.

These compositions can be cured to form pressure-sensitive, adhesive silicone elastomers, which have the have desirable physical and electrical properties of the known silicone elastomers and also after applying pressure z. B. on metals, fibers, cloths and others articles made of natural and synthetic material adhere.

One application form of the elastomers which can be produced from the compositions according to the invention is that Manufacture of pressure-sensitive adhesive strips without a backing, which are elastic and used as insulation or Reinforcement material can be used. For this form of application is the adhesion of the elastomers especially important to each other. Hardened and even post-cured elastomers can be exposed to heat fused into a substantially homogeneous mass. This property was with the previously known Silicone elastomers not available.

Another use of the elastomers that can be produced according to the invention is to apply them to solids apply a coating of the cured elastomers. These solids can be metal or metal alloys be like steel, phosphate-containing steel, aluminum, anodized aluminum, copper, tin, Brass, bronze or silicon-containing substances such as glass, fiberglass, ceramic or porcelain or organic Fibers such as wool, cotton, nylon or dacron, cellulose materials such as wood, paper, cellophane, Cellulose acetate or ethyl cellulose, organic elastomers such as natural rubber, chloroprene or Molding compounds that can be thermoset to form elastomers, the diorganopolysiloxanes, boron compounds, contain usual hardeners and fillers

Applicant: Union Carbide Corporation,

New York, N.Y. (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 14, 1958 (No. 728 098)

Frank Fekete, Verona, Pa. (V. St. A.), has been named as the inventor

Butadiene-styrene copolymers and plastics such as polyvinyl chloride, polyethylene or polyacrylic ester.

The organic substituents of the diorganopolysiloxanes are a) hydrocarbon groups that are free from aliphatic are unsaturated components; in addition, one or more of the following as desired Groups: b) unsaturated hydrocarbon groups,

c) halogen-substituted hydrocarbon groups and

d) cyanoalkyl groups.

The diorgano-substituted polysiloxanes can be linear or cyclic polysiloxanes.

Preference is given to substituted polysiloxanes in which the hydrocarbon groups are free from aliphatic, unsaturated components are made up of methyl, ethyl, amyl and phenyl groups and the any olefinically unsaturated hydrocarbon groups present from vinyl, allyl and cyclohexenyl groups exist. Any halogen-substituted hydrocarbon groups present are chlorine or fluorine substituted methyl, propyl, butyl or phenyl groups. Any cyanoalkyl groups present are / J-cyanoethyl, y-cyanopropyl or <5-cyanobutyl groups.

The diorganopolysiloxanes used as starting materials, which are as free as possible from mono- and trifunctional Compounds should contain organic groups and silicon atoms in one

209 679/347

3 4

ratio that pretty much exactly 2.0 organic groups organic groups are hydrocarbon groups, per silicon atom. Slight deviations from such as phenyl, ethyl and methyl groups, as well

this ratio of 2: 1, for example 1.95: 1 unsaturated hydrocarbon groups, such as vinyl,

or 2.05: 1, do not have any disadvantages. Allyl and cyclohexenyl groups, halogen-substituted

If the diorganopolysiloxane is olefinically un- 5 hydrocarbon groups, such as mono- or polychloro-

contains saturated hydrocarbon groups, are or are fluorine-substituted alkyl or aryl groups,

preferably 0.037 to 0.070 ° / ₀ of the silicon atoms Aminoalkylgruppenwiey-aminopropyl-undo-amino-

associated with these groups. This results in butyl groups, cyanoalkyl groups, such as / 3-cyanoethyl,

during hardening, an average of five to twenty carbalkoxyalkyl-y-cyanopropyl and <5-cyanobutyl

Networking points per molecule. io groups, finally carbalkoxy groups, such as /? - Carb-

When the diorganopolysiloxanes are halogen-substituted oxyäthyl-, γ-carboxypropyl and γ-carboxypropyltuierte Hydrocarbon groups or cyanoalkyl groups. There can also be hydroxyl and alkoxy groups contain, preferably 0.1 to 1, preferred silicates are used, wise 0.25 to 0.75% of the silicon atoms with these The alkoxy groups in the alkoxy-containing silicon groups tied together. 15 compounds are preferably methoxy, ethoxy,

The diorganopolysiloxanes can be used as pourable propoxy or butoxy groups.

Liquids are used in which proportion- The silanes generally contain only one

moderately short chains of low molecular weight linear silicon atoms per molecule, while the polysiloxanes_

Polysiloxanes are present. However, 2 to at least 35 silicon atoms can also be used, preferably

Organopolysiloxanes with the same composition can contain 20 2 to 20 silicon atoms per molecule,

use which, however, have a higher viscosity, longer The polysiloxanes are preferably straight-chain.

Have chains and higher molecular weights. The hydroxyl-containing silanes contain at least

Viscosity can be so high that the mass almost solidly has one hydroxyl group, preferably at least two

is and hardly flows. Hydroxyl groups per molecule. The hydroxy-containing

The usual polysiloxanes can be used as boron compounds, in particular six or more

uses and are preferred that contain at least 1 boron atom hydroxyl groups per molecule. Examples

and contain at least 1 oxygen atom, such as the saturated hydrocarbon substituents

Biric acids. Boron compounds that only contain boron, oxygenated hydroxysilanes, such as diphenyldihydroxysilane,

and contain hydrogen atoms, are best trimethylhydroxysilane, phenyldimethylhydroxysilane,

suitable. 30 phenyltrihydroxysilane, methyltrihydroxysilane and

The amount of boron compounds can be within silicates, such as partially hydrolyzed tetraethylsilicate

vary over a wide range. There can be less and the condensed polymers produced from them,

than 0.05 parts up to more than 10 parts by weight, in addition to silicates such as diethoxy-di- (2-ethylhexane

preferably 0.1 to 4 parts by weight of the boron compound diol-1,3) silicate, diethoxy-o-o-die- (2-ethylhexanediol-

on 100 parts by weight of the diorganopolysiloxane 35 l, 3) silicate and similar compounds,

be turned. Hydroxy-containing polysiloxanes and relative

In the preparation of the organo-low molecular weight polysiloxanes with terminal hydroxyl groups according to the invention, the usual fillers of the provided polydiorganosubstituted siloxanols of the "highly reinforcing" type such as carbon black, for example, can be used. B. with one holding chains with 2 to 35 or more dihydrocarbon partial diameters of 300 to 850 Å and inorganic 40 siloxy units (R ₂ SiO) per molecule and through compounds such as finely divided silica, for example, at least one hydroxyl group per molecule. Particle sizes of less than 500 ΐημ and with a surface area of more than 50 m ² / g correspond to the general formula.

Further examples are: titanium oxide, iron oxide, zinc (OH) ₃ _ _a ^ R

oxide, aluminum oxide, aluminum silicate, zirconium 45

silicate, barium sulfate-zinc sulfide, infusor earth, Kai- R _a - Si - O -

Si - O

- Si - R ₆

cium carbonate, quartz and finely divided silica,
which are bound to alkoxy groups on their surface
contains.

Further examples of boron compounds are the 50 R = hydrocarbon-halogen-substituted carbo-esters of boric acids, boric anhydride, borohydrides; hydrogen, cyanoalkyl, aminoalkyl or carboxy removers from such hydrides with nitrogen compounds alkyl radical. R '= alkyl or aryl radical. a - number of complexes formed again diborane complex with 0 to 2, b = number from 0 to 3 and χ = number from 2 to 35. Ammonia (B ₅ H ₅ · 2 NH ₃ ), triethanolamine borate - The substituents R and R 'can identical or identical and triisopropanolamine borate; Complexes of such 55 be divorced.

Hydrides with hydrocarbons such as Diphenyl- The alkoxy-containing silicon compounds contain

decaboran; the alkali and alkaline earth metal derivatives at least one, preferably at least two alkoxy

or metal complexes of boric acids such as sodium groups, per molecule. The polysiloxanes can

borate, potassium pentaborate and magnesium borate. particular six or more alkoxy groups per molecule

Contained in the hydroxyl-containing and alkoxy-60.

group-containing silicon compounds can be They have the general formula: organosilanes or relatively low molecular weight polysiloxanes, which optionally contain Rn'Si (OR ') ₄ _ _B identical or different organic groups

contain .. Such compounds are hydroxyl 65 R "= hydrogen atom or alkyl, aryl, alkenyl

silanes, alkoxysilanes, hydroxyl-containing poly radicals, organosubstituted alkyl radicals, such as aminoalkyl,

siloxanes and polysiloxanes containing alkoxy groups. The carboxy-alkyl, cyanoalkyl, chloroalkyl radical or organo-

optionally present, silicon-bonded substituted aryl radical, such as aminoaryl, carboxy

5 6

aryl, cyanaryl or chloraryl radical. R '= alkyl or elastomeric organic peroxides used

Aryl group, η - number from 0 to 3 can be drawn, including those that have a

As alkoxy-containing polysiloxanes with terminal selective curing, especially the unsaturated ones

Effect alkoxy groups of the general formula hydrocarbon groups.

5 A particularly striking property of the

(OR ') ₃ -a / R \ (OR') ₃ -6 compositions according to the invention consists in the fact that they

I within the entire hardened mixture

R _a - Si - O - I Si - OI - Si - Rs are moderately adhesive. When the mass is cut through, each of the newly formed surfaces remains adhesive. Therefore, each of the two pieces at the cut surfaces can be preferred to the original. R = hydrocarbon, halogen objects are combined or adhered to other substances by applying substituted hydrocarbon, cyanoalkyl, amino pressure,
alkyl or carboxyalkyl radical. R '= alkyl or aryl if the filler material consists mainly of a radical, a = number from 0 to 2, b = number from 0 to 3, 15 inorganic filler, such as finely divided silica, χ - number from 2 to 35. The substituents R and R ', the elastomer as electrical insulation may be the same or different. material use, this also applies to vibration

The amount of the hydroxy containing silicon compound does not slide off or slip off. If the filler is made

can be varied within a wide range. For the most part it is made of soot, so the inventive

can use less than 1 part up to 100 parts by weight, 20 according to elastomers as electrical semiconductors

preferably 4 to 80 parts by weight of the total amount are used.

on hydroxyl-containing Si compound and on alkoxy- One of the greatest advantages of the invention

containing silicon compounds per 100 parts by weight of elastomers lies in the fact that they are pressure-sensitive

of the diorganopolysiloxane can be used. Adhesive strips can be produced without an underlay

According to the invention, a combination can also be used which are hardly or not at all sticky when touched by hydroxy-containing, alkoxy-containing silicon compounds, and that they fertilize themselves through a tensile strength that is partly monomeric from 49 to 70 kg / cm ² , an extensibility of 300 to alkoxysilanes and hydroxysilanes and on the other hand 400% and a tensile strength between 7 and part hydroxyl-containing and alkoxy-containing poly 13 kg / cm ² . The adhesive strips can contain in versiloxane. With such a different width and with a thickness of 0.102 to position, the monomeric compound is preferably 2.54 mm, preferably from 0.127 to 1.016 mm, in amounts of 0.5 to 30 parts by weight of the diorgano.

polysiloxane and the polymeric substance in quantities The pressure-sensitive adhesive polysiloxane of 3.5 to 50 parts by weight, based on the adhesive strip without a backing, are preferably to organopolysiloxane. The monomeric compound 35 rolls wound, preferably so that a piece of paper or art is preferably used in quantities of 1 to 10 weight between the surfaces, the polymeric substance preferably comes to lie in quantities of a fabric film layer. Other suitable from 6 to 20 parts by weight used. In these intermediate layers, for. B. glass fabric, paper, Of course, more than two nylon, cellophane and plastics such as polymers and can also be mixed Components must be present. 40 copolymers of vinyl chloride and polyvinylidene

Examples of alkoxysilanes are with the same or chloride, also by reaction of adipic acid

various alkyl or aryl substituents with hexamethylenediamine and products

see alkoxysilanes, unsaturated hydrocarbon-like polymers. You want paper as an intermediate layer

radicals, carrying alkoxysilanes or halogen-substituted ones, preferably with wax or another material

Hydrocarbon alkoxysilanes, cyanoalkylalkoxysilanes, 45 are treated or coated.

Aminoalkylalkoxysi] ane, Carbalkoxyalkylalkoxysilane, In some cases it is desirable to use the invented

Silicates such as tetraethylsilicate and compositions according to the invention produced therewith for 1 day to 1 week

condensed polymers, as well as silicates such as room temperature to undergo an aging process

ethoxy-di- (2-ethylhexanediol-1,3) -silicate, diethoxy-di- pull or the mixture at elevated temperatures

(triethanolamine) -silikat-n-dioleate, diethoxy-o, o-di-di-50 (above 12O ⁰ C) to age for at least 1 hour.

(2-ethylhexanediol-1,3) -silicate and diethoxy-O, O-di- This becomes the filler of diorganopolysiloxane

(triethanolamine) -silicate-n, n-dioleate. better wetted, and there are also disturbing volatile

The compositions according to the invention are suitable for removing substances.

Production of silicone adhesives and pastes, which are used as After aging, the hardening thin film coatings are applied to the mass and added to this additive, whereupon it can be hardened in the heat and hardened afterwards. The inventiveness desired a repeated heat treatment at about contemporary compositions may also be in solvents, such as 177 ° C, preferably dissolved at 25O ⁰ C for 24 hours voraromatischen hydrocarbons and is taken out. Post-curing is used to create coatings and films in these solutions - physical properties of the elastomers. 60 stabilize and also their electrical properties

For the pressure sensitive shafts of the invention to improve.

There are numerous adhesive polysiloxane elastomers. The following examples serve to illustrate the

other possible uses. You are suitable invention,

for example for the production of seals, shape example 1
bodies, pressure sensitive adhesive strips, foils and 65

Diaphragms. A diorganopolysiloxane was used in the

The amount of finely divided pebbles specified in the compositions according to the invention in Table I can be used as hardeners which is usually mixed to harden silicone acid. The results listed in Table I were then

other ingredients mixed with the mass. In each case, 1.2 parts were used as the hardener Dichlorobenzyl peroxide used on 100 parts of diorganopolysiloxane.

Table I.

Parts of diorganopolysiloxane, .. ,, ... ,,

Parts of filler material,,,

Parts boric acid,

Parts of ethyltriethoxysilane

Parts of ethoxy-endblocked dimethylpolysiloxane oil *. Parts provided with OH groups at the chain ends

Dimethylpolysiloxane oil **

B. Dimensions 100 E. A. 100 C j D 40 100 100 40 100 0.5 40 40 0 40 0 0.75 0 0 0.5 6th 3.6 0 6th 0 6th 6th 0 6th 0 6th 0 0

100
40
0.5 1.2 6

* A dimethylpolysiloxane oil end-blocked with ethoxy groups with an average of one ethoxy group per terminal silicon atom and an ethoxy group content of 12 to 15 percent by weight.

** A dimethylpolysiloxane oil with hydroxyl groups at the chain ends and an average of one hydroxyl group per terminal silicon atom and a hydroxyl group content of 2.5 to 3.2 percent by weight.

The stated above collated 25 and F blended and this cured thereon, nachGemische were 15 minutes cured at 120 ⁰ C in one and above on their physical properties form hardened and then for 24 hours at 250 ° C transactions assayed for. The resulting post-hardened. Data were as follows:

The following table shows the physical properties each of the hardened masses listed.

Table II

xi arte train Stretch Tear Percent (Shore) A strength availability strength tuale Dimensions 76 kg / cm ² ° / o kg / cm ² Duration-
defor 68 64 200 5.3 mation A. 66 66 325 6.7 0 B. 63 56 265 4.8 0 C. 68 64 300 6.9 10 D. 66 58 375 7.7 10 E. 74 430 7.4 20th F. 20th

The torn dumbbell-shaped specimens obtained in the tensile strength determinations were wrapped on top of each other (the wider parts protruded at least 1.2 cm above each other) and through one of Thumb and forefinger pressed against each other to check whether the different elastomers are used were pressure-sensitive, adhesive substances. The samples of compositions A and B showed no tendency to adhere to one another. The Compound C samples showed little or no tendency to stick together. For the samples produced according to the instructions D, E and F, on the other hand, forces from 3.4 to 8.7 kg are required to detach the superimposed parts from each other.

By adding small amounts of iron oxide, for example 1 to 5 parts per 100 parts of polysiloxane rubber (preferably 2 parts), the silicone compounds become during the curing and heat aging treatments stabilized, thereby avoiding difficulties during the hardening process. There were z. B. 2 parts by weight of iron oxide with the masses E

30th hardness
(ShoreA) Table III Stretch
availability
° / o Tear
strength
kg / cm ² Percent
tuale
Duration-
defor
mation Dimensions
35 68
69 train
strength
kg / cm ² 390
330 87
79 20th
10 E.
F. 72
61

The adhesion values to shear forces were for those manufactured according to these regulations Samples 4.8 kg and 8.2 kg, respectively.

Example 2

To produce Compound S, a polysiloxane rubber was used as the starting material, which consisted of dimethylpolysiloxane units (87.65 percent by weight), ethylvinylsiloxane units (0.35 percent by weight) and diphenylsiloxane units (12 percent by weight), plus 35 parts of a reinforcing silica filler, 4.5 parts of a dimethylpolysiloxane oil end-blocked with ethoxy groups with a content of 12 to 15 percent by weight of ethoxy groups, 4.5 parts of a dimethylpolysiloxane oil provided with hydroxyl groups at the chain ends with a content of 3 percent by weight of hydroxyl groups and 2 parts of iron (III) oxide were added. 0.5 part of diphenyl diethoxysilane, 0.5 part of diphenylsilanediol, 0.5 part of boric acid and 1.2 parts of dichlorobenzoyl peroxide were added to 100 parts of the composition S and the mixture was ground to give mixture T. The compositions S and T were cured for 15 minutes at 120 ⁰ C in the mold and post-cured for 24 hours at 25O ⁰ C. The resulting elastomer T had a highly pressure sensitive adhesive surface, while S showed no such property. The physical properties are shown in Table IV.

Table IV

10

Dimensions hardness
(Shore A) tensile strenght
kg / cm ² Extensibility
7o Tear resistance
kg / cm ² Percentage
Permanent deformation Adhesiveness
versus shear force
kg S.
T 45
53 55
61 500
370 4.2
4.4 0
25th 0
7.2

Claims (2)

PATENT CLAIMS: 1. Molding compositions which are heat-curable to elastomers and contain diorganopolysiloxanes, boron compounds, customary hardeners and fillers, characterized in that they additionally contain at least one hydroxyl-containing silane or one hydroxyl-containing polysiloxane and at least one alkoxy-containing silane and / or alkoxy-containing polysiloxane. 2. Composition according to claim 1, characterized in that at least some of the alkoxy groups Diorganopolysiloxane contains 2 to 35 silicon atoms per molecule. Considered publications:
U.S. Patent No. 2,721,857. © 209 679/347 10.62