DE2703605A1 - CURABLE ORGANOPOLYSILOXANE COMPOSITION - Google Patents

Description

The invention relates to a curable organopolysiloxane composition with an organopolysiloxane with at least two vinyl groups bonded directly to the silicon atoms of a molecule, an organohydrogenpolysiloxane with at least two directly to the silicon atoms of a molecule bonded hydrogen atoms and a platinum catalyst.

Various organopolysiloxane compositions have been proposed which have, as essential components, an organopolysiloxane with vinyl groups bonded directly to the silicon atoms, and also an organohydrogenpolysiloxane with hydrogen atoms bonded directly to the silicon atoms as well as a platinum catalyst, these constituents on heating by hydrosilation with the formation of crosslinks can harden. However, these organopolysiloxanes cannot be used in a so-called single pack for long periods of time be stored without being too lighter, and so far it had to be

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Stabilizing agents are added in order to obtain sufficient storage time at room temperature.

Stabilizing agents for this purpose are amines or amide compounds, see e.g., U.S. Patent 3,188,299; Sulfides or sulfoxide compounds, see e.g., U.S. Patent 3,453,234; Phosphine compounds, See, e.g., U.S. Patent 3,188,300; Ionic substances containing heavy metals, see, for example, US Pat. No. 3,532,649 and acetylenic compounds, see, for example, US Pat. No. 3,445,420. Organopolysiloxane compositions containing these stabilizers, however, spread unpleasant odor, contaminate the working atmosphere and increase leakage currents in electronic devices Circuit elements to which they have been applied.

Organosiloxane compositions with the conventional stabilizers can admittedly for considerable periods of time without to be stored to gel. However, heated and hardened or cured products show wrinkles or irregularities at. their "surfaces as the result of internal tensions that arise in usually caused by the curing of the compositions. These stresses start on the surface layer and then move further into the depths with a delay. This phenomenon can be explained by the fact that it is in the surface layer any stabilizing agent present is rapidly broken down by evaporation or decomposition, causing the composition to adhere to the Surface undergoes hardening and the hardening in the

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deeper areas by the stabilizing agent remaining there is delayed. Therefore, when such compositions are used as coating materials for semiconductors of complicated structure or in particular as a transition or buffer layer of integrated circuits or other electronic circuit elements are used, this can result in disadvantages such as interruption of connection points and interruptions in operation.

The object of the invention is to provide an organopolysiloxane To create a composition of the type mentioned, which can be stored for long periods of time without these disadvantages can. The stabilizing agent used for this purpose should be synthesized comparatively simply by means of conventional methods can be.

The organopolysiloxane composition of the present invention, which these Solves tasks is characterized by the fact that the

(a) Organopolysiloxane has the following average unit formula ^

^(CH 2 ^{= C1I)} a ^R b ^SiC Wb '
2

where R is the same or a different monovalent hydrocarbon group denotes without an aliphatically unsaturated radical, a has a value from 0.00025 to 0.5 and b a value from 0.75 to 2 has the proviso that the sum of a and b is 1.25 to 2.25,

(b) Organohydrogenpolysiloxane, which is not aliphatically unsaturated Has residues, is provided in such an amount that 0.5 to

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4 hydrogen atoms directly to the silicon atoms per vinyl group are provided in component (a) and that composition (d) contains an alkynyloxy group Has organopolysiloxane, which in a molecule at least a monovalent hydrocarbon group with a -CsC- bond, which is connected to the silicon atom via an oxygen / silicon bond.

The organopolysiloxane composition according to the invention can Stored for more than a year at room temperature in good condition without gelling or without increasing viscosity will; in addition, it can be hardened or hardened quickly by heating at temperatures between about 100 to 150 ° C. to produce a film that is free from wrinkles or other defects on its surface. Because These good properties in film formation can be used by the composition according to the invention in particular for coating used by electronic circuit elements such as transistors and integrated circuits with complicated structures will.

The vinyl group-containing organopolysiloxane used as component (a) in the composition of the present invention is through the specified average unit formula is described, where

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R the same or a different, substituted or unsubstituted, monovalent hydrocarbon group without

Rest is.
aliphatically unsaturated I Examples of these monovalent hydrocarbon groups R are methyl, ethyl, propyl, butyl and phenyl groups, in which the hydrogen atoms can be completely or partially replaced by halogen atoms, for example chlorine atoms. In this formula, a has a value from 0.0025 to 0.5, preferably from 0.02) to 0.3 and the value from b 0.75 to 2, preferably 0.8 to 2, with the proviso that the sum from a and b is 1.25 to 2.25, preferably 1.4 to 2.02, depending on the type of cured end product.

The organopolysiloxane as component (a) is composed of monofunctional siloxane units such as R, SiO. _c and (CH_ = «CH) R_SiO_ _c , e.g. (CH ₂ = CH) - (CH ₃ J ₂ SiO _{0 5 #} (CH ₃ J ₃ SiO _{0 5} and (CH ₂ « = CH) (CH ₃ ) (C ₆ H ₅ ) SiO, difunctional siloxane units, such as (CH_ «CH) -RSiO and R ₂ SiO, _{e.g. (CH 3} J ₂ SiO, (C ₆ H ₅ J ₂ SiO and (CH ₂ = CH) (CH ₃ ) SiO . _c and trifunctional siloxane units, such as CH ₀ = CHSiO, _ and RSiO, including

i 1.3 I # 3

CH-SiO, _c and CH _c Si0, _c , together, either alone or

J I »-> DJ 1, ->

Combinations of the same.

Examples of organopolysiloxanes containing vinyl groups as component (a) are an organopolysiloxane consisting of 55 mol% of C _<: H _c Si0 _ic units, 20 mol% of (CH,) (CH ₀ -CH) SiO units and 25 Mol% of (CH ₃ ) SiO units, an organopolysiloxane composed of 70 mol% of CH-SIO ₁ units,

J I # 3

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10 mol% of (CH ₃ ) - (CH ₂ = CH) SiO units and 20 mol% of (CH ₃ ) _Sio units and an organopolysiloxane according to the following formula

CH

where ρ is an integer of at least 2 or

^C 6 ^H 5

CH ₀ = CH-Si-OT-Si-O-

CH ₂

^CH

-Si-O-I

^C 6 ^H 5

-Si-CH = CH _2;

r ^CH 3

where q and r are positive integers.

The organohydrogenpolysiloxane as component (b) is used as a crosslinking agent according to the invention. It is required that the component is aliphatically saturated. In the context of the invention it is preferred that the component

(b) has excellent compatibility with component (a). If this compatibility is not sufficient, the component will

(b) excreted from the composition during curing,

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and the cured end products then show no satisfactory results mechanical strengths.

Examples of the organohydrogenpolysiloxanes of the invention are compounds of the following formulas

CH, / CH ^ \ / η \ CH,

I H-Si-0-j-Si-0-4-j-Si-0-j-Si-H _f

where s is a positive integer, (2)

CH,

CH, -Si-04-Si-0-4-Si-0 CH

-Si-O- -Sl-CH ₃ ,

ν ^CH 3

where t, u and ν are positive integers,

(3), _rH \

CU Q-! Π Cl tr

CH

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(4)

Si

CH

CH, H

ι 2--

Si

\ O

O

\ / Si

H CHx

Si CH,

\ I

CH, H

\ / Si

HO

St.

' \ CH, O

CH,

Si

Si

/ \ H CH

O
Il

CH / CH. I ^J

CH, O-C-CH-CH ₂ -Si-O-

CH,

I.
CH.

-Si-O

• Si — 0

/ v \ ^CH 3 -Si-O-

/ X

CH

CH,

—OCH

I CH,

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where ν, w and χ are positive integers.

According to the invention, component (b) is added in such amounts that O _r 5 to 4, preferably 1.0 to 2.0, hydrogen atoms bonded directly to the silicon atoms are present per vinyl group of component (a). If the number of these hydrogen atoms is less than 0.5, the hardened product has poor hardness; Conversely, if the number of hydrogen atoms is greater than 4, there is a tendency for hydrogen bubbles to occur during heat curing.

It should be added that a single organohydrogenpolysiloxane (b) or a mixture of the organohydrogenpolysiloxanes can be used. Through different uses of the organohydrogenpolysiloxanes in combination or as a mixture, the desired compositions can be used in large ranges changing physical properties, for example in terms of peeling or their adhesive force will.

Any plantin catalyst (c) suitable for hydrosilation can be used as the catalyst used in connection with the invention. For example, reference is made to chloroplatinic acid, which can also be modified with alcohol, according to US Patent 3,220,972 directed to the Chlorplatineäure- olefin according to US Patent No. 3,159,601 and 3,159,662, to

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Platinum black or on aluminum oxide mixed with platinum or the same silica. Chloroplatinic acid or

their complex with an olefin are preferably dissolved in a solvent such as an alcohol, a ketone, an ether or a hydrocarbon is used. The firm ones Catalysts can be used in finely divided form to improve their distribution in the compositions. The supports of the solid catalysts containing platinum preferably have a small grain size and accordingly have a large specific surface.

The amount of the platinum catalyst to be used according to the invention Component (c) depends on the desired curing rate. For economic reasons are in view on a well cured product preferably at least 0.5 ppm by weight, in particular 1 to 30 ppm by weight based on the Total weight of components (a) and (b) used when the catalyst, e.g. chloroplatinic acid or its complex, with the Organopolysiloxane is compatible, or 20 to 500 ppm by weight again based on the total weight of components (a) and (b) if the catalyst is solid, e.g. platinum black.

The alkynyloxy group-containing organopolysiloxane as component (d) according to the invention, its molecular configuration

is

preferably linear with a relatively small number of silicon atoms per molecule, for example less than 100

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at least one monovalent hydrocarbon group per molecule on, for example, an alkynyl group with a -CbC- bond, which is attached to the silicon atom via an oxygen / silicon bond connected.

If the alkynyl groups are bound directly to the silicon atoms, as in the case of an organopolysyl oxane having alkynyl groups, the stabilizing efficiency is lower than that of the component (d) according to the invention.

Preferably more than 30 mole percent of the total siloxane units of component (d) the siloxane units to which the alkynyloxy groups are bonded. The advantage of this structure has been proven experimentally when used in an equivalent Amount compared to the same organopolysiloxane with less Alkynyloxy content.

According to the invention, the alkynyloxy group of component (d) preferably has three or more carbon atoms; for example it can be a propynyloxy group CHaC-CHj-O- or es These may be higher groups such as 1,1-dimethylpropynyloxy group compared to the ethynyloxy group CHaC-O- from the standpoint of the stabilization efficiency and the ease of manufacture

CHeC-C-O-, the butynyloxy group CHeC-CHj-CH -0-, the 1-methyl-

CH ₃

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1-ethylpropynyloxy group HCs C-C-O-, and the "l-methyl-1-

C ₂ H ₅

Isobuty1propyny1oxy group

HCeC - C - 0.

CH, -C- CH, ³ H ³

The alkynyloxy group can in principle either at the ends the molecular chain or in between. According to the invention, however, it is preferred that this alkynyloxy group or groups are provided in the middle between the chain ends. With regard to its configuration, component (d) be linear or branched; it can also have a cyclic structure.

Examples of component (d) are as follows:

CH ₃ / CH ₃ \ · CH ₃ \ CH ₃

CH, - Si — 0 — L-Si 0-L — Si— θ] —Si CH,

³ I ι \ I

_CH3 \ O] \ CH _3/7 CH

CH, -C-CH

IH CH

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CH

■> I

CH

CH ₃ / CH, \ _r -Si-O L-Si-O

\'O

CH

-C-CH, I ^

III

CH

Ib CH, I -> -Si-CH,

CH

CH,

CH_ — Si — 0 ι CH,

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(5)

CH, -Si-O
-> I.

CH,

/ CH

Themselves

(6)

CH, CH,
³ I ³
HChC -C-O-Si-O
I.

CH

CH

CH ₃

Si-O
I.

CH-

CH, CH, I ^ ι 3

-Si-O-C-C = CH I I

CH,

8 ^CH 3

CH-Si-0- J ι

CH,

CH, NI ■>

-Sii

CH, I 'C III
CH CH,
I ■ *

-Si — ΟΙ

CH,

-Themselves.

CH, -Si-0

I.
CH,

Themselves-

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CH

CH, -

(10)

CH

CH, - ³

CH-CC ₉ H, ■> ι ^

C IH CH

(11)

CH, / CH,

ι 3 / ι

CH ₃ -Si-O (-Si-O

CH,

CH, —C—

C ti CH

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Component (d) preferably has excellent compatibilities with the two components (a) and (b). Bad Compatibility can result in a longer curing time, uneven and locally inadequate curing of the composition as well as making the cured product opaque.

Component (d) can be easily synthesized, for example by the following steps: addition of alcohol having an acetylene bond to an organohydrogenpolysiloxane with (CH ₃ ) (H) SiO units by dehydrogenation in a solvent in the presence of an alkali metal alcoholate or an amine, Neutralizing the reaction mixture using acid or halosilane and removing the solvent and the low-boiling compounds from the reaction mixture by distillation. The ratio of the organohydrogenpolysiloxane and the alcohol having an acetylene bond in the above reaction is such that the number of hydroxyl groups in the alcohol is at least 1 per sSi-H bond in the organohydrogenpolysiloxane. It is also recommended that the solvent and the low-boiling compounds, for example compounds with a boiling point less than 150 ⁰ C, as completely as possible to be removed. If this separation takes place in insufficient

• v to the extent that wrinkles may appear on the surface of the cured Product occur, the mechanism being such that the low-boiling compounds with the alkynyloxy groups

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evaporate from the surface layer of the connection when heated, so that the hardening reaction begins first at this surface layer and only progresses in depth with a delay.

Some examples of the alcohols containing the acetylene bond, which are used in the above reaction are as follows:

(1) 'HCeC-CH ₂ -OH

(2) HCbC-CH ₂ -CH ₂ -OH

, 3, CH ₃

CH ₃ -C-Cg CH OH

(4, CH ₃

CH, CH_— CC m CH

^ ³² I.

ν OH

(5) CH, CH

I ³ ι ³

CH, - CH - CH - C - C s CH

^{3 2} I.

OH

According to the invention, component (d) is added in such an amount

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give that 2 to 10,000 moles, preferably 100 to 50,000 moles, the -CaC- bonds per mole of the platinum atoms in component (c), ie the platinum catalyst, so that the resulting Composition a long storage option is communicated.

Werden.-If the composition of the invention can be prepared by simply mixing the components (a) to (d) is obtained it is heated to temperatures between 1OO and 150 ⁰ C or higher, a good curing reaction takes place. In principle, it can be said that the greater the proportion of component (c), the faster curing takes place. In order to prevent the possible occurrence of cracks in the hardened solid product, the hardening reaction is preferably carried out with gradually increasing the temperature.

Various additives can be added to the composition of the invention depending on the desired result. For example, to improve the strength of the resulting, cured product, an organopolysiloxane of the resin structure consisting of units of SIO, (CH-CH) R ', SiO ^,. , R "SiO,. C and optionally (CH ₀ ^ CH) R ¹ SiO

and / or R * SiO are added, where R ^{1 is} a monovalent,

Hydrocarbon group without an aliphatically unsaturated radical is like them
'for example in U.S. Patents 3,699,073, 3,284,406 and 3,436,366

are described. The amount of additives used

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is at most 40, preferably 30 wt .-% of the total weight the organopolysiloxane constituents including components (a) and (b) are limited, and the number of directly Hydrogen atoms bound to the silicon atoms of the entire composition should be 0.5 to 4 per vinyl group »not to the silicon atoms are bonded.

The composition according to the invention can also be a filler be added with up to 70 wt .-% based on the total mixture and to reduce the shrinkage during the Curing or the coefficient of thermal expansion of the cured product or to improve such properties as thermal stability, weather resistance, chemical resistance, flammability, mechanical strength and for Reduction in gas permeability. Examples of such fillers are quartz powder, glass fibers, carbon black, metal oxides such as aluminum oxide, iron oxide and titanium oxide, and metal carbonates such as Calcium carbonate and magnesium carbonate. Pigments, dyes or antioxidants can also be used in the composition according to the invention «To be built into. The composition according to the invention can as a solution or dispersion in organic solvents, such as toluene or xylene, according to the present needs be used.

The invention is explained in more detail below with the aid of a few examples. Weight data are given in% by weight. Me, Ph and Vi denote methyl, phenyl and vinyl groups, respectively.

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Example 1:

A mixture of four parts of an organohydrogen polysiloxane

the formula

No

η— ει — οι

Me

/ H
I.

-Si-O
I.
Me

/ Me

Si-O
ι

\ Me

Me

—Si-H

/ 12 Me

and 100 parts of a dimethyl polysiloxane with vinyl chain ends and a viscosity of 50,000 centi st okes measured at 25 ⁰ C, the vinyl group content was 0.006 g mol / 100, 0.02 parts of a solution of chloroplatinic acid in butanol was added (2% platinum concentration) was added. Then one of the various compounds (d) according to the following table was added to the resulting mixture in the stated amount, followed by sufficient mixing to bring about a homogeneous composition.

The mixture obtained in this way was observed or examined ^{with regard to its appearance and the time required for gelling at 40 ° C.} Furthermore, each composition was applied to a glass plate, followed by heating and curing at 2CO ⁰ C for 30 minutes to produce a cured film. The cured films were examined for gloss and for wrinkling on their surface. The results obtained are shown in the following table:

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attempt Compo lot Appearance Gelation hardened Movie No. nent
(d) # »#» · » Time
(Days) Wrinkling shine 1 A " ^! 500 transparent 2 no excellent 2 _B ::: 500 transparent 25th no excellent 3 C "' 5OO transparent 39 no excellent 4th _D ::: 500 transparent 23 no excellent 5 Ε "= 500 somewhat opaque 23 no Well 6th _F : j: 500 transparent 1 no excellent 7 ^3:
8th-
9 »
1O » G » ^!
H " ^:
I " ³
j ::: 20th
500
500
500 opaque
opaque
transparent
transparent 28
60
1
1 sth. wrinkles
education
strong case
education
no
no no
shine
Well
excellent
excellent

Notes: ^J: Control

Me

Me — Si- Οι

Me

\ Me

Me

) J Si-O-

/ 2 \ Me

Me

-Si-

ι
/ β Me

-Me

- Me

I.
Me-Si-O-

Me

/ χ

Si
I.
\ Me

—O-j-i-Si— ( / 5 \ Me

Me ι -Si-Me

/ 3 Me

Me I.

Me — Si — Οι

Me

-Si-Οι

\ Me / 8 Me

Me

Si — Me

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** D

Me

** E

Me I.

Me — Si — Οι

Me

Si — O-U-Si — Οι / Ii

Me / 4 \ Ph Me

-Si-Me / 4 Me

* # F

Me
I.

X-Si- ΟΙ

Me

/ Me

'-Si-O I
Me

/ 6 Me

Me

-Si-X I

♦♦ G Sn (C ₇ H ₁₁ -COO).

♦♦ Η X ₂ SiPhMe

♦♦ I Me / Y \

I ■ / ι

Me-Si-O-Lsi-0

¹ '

Me \ Me

/ 2

/ Me I

-Si-O I

Me Me

-Si — Me I

6 Me

Me / Me \ Me

HC ξ C — Si — 0 — Lsi — ΟΙ ι

Me \ Me / β Me

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In the formulas AF and H, see above, X means the following group:

Me I.

HCsC - C - ΟΙ Me

In formula I, see above, Y means the following formula:

Me

HCaC — C—

Me

:::: « Q ± _e respective amount in experiments 1 to 6 and 8 to 9 is expressed in terms of the HClC / Pt molar ratio and in experiment No. 7 as the Sn / Pt molar ratio.

The same procedure as in Experiments 1 to 6 above was repeated except that the amount of component (d) was chosen instead of 500 with 5,000 to make a composition. The gel time of these compositions was in tested in the same way and found to be more than three months. Separately, each composition was tested in the same manner as above to form a cured film. It was found that the upper *

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surfaces were wrinkle-free and had excellent gloss.

Example 2; The following components became a homogeneous mixture

manufactured:

76.4 parts of an organopolysiloxane consisting of 55 mol% PhSiO,, .- units, 20 mol% ViMeSiO units and 25% Me ₂ SiO units;

13.4 parts of an organopolysiloxane of the formula

Me H

Si

/ \ H / ° ° _X ^ Me

) si. Si Me Me \ / \ ι

0 0 CH ₀ -CH-Ph

Si

/ \ H Me

9 parts of an epoxy group-containing organohydrogenpoloxane of the formula

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Me H

\ / Si

Me

Me

Si

CH _? CHpCH--CH-CH-CH ₉

Si / \ H Me

1.27 parts of an organopolysiloxane of the formula

Si-O

Me

I.
Si-O-

Me

-Si-Me

7 Me

Me-C-C = CH ι

CH ₂ Me

and 0, O64 parts of the same solution of Example 1. This mixture was allowed for three months at 25 C ⁹ are of chloroplatinic acid in butanol invention. It was found that there was practically no change in viscosity. Independently of this, the mixture was applied to an aluminum plate followed by heating at 150 ° C. for 16 hours to form a cured film which was then extremely transparent and wrinkle-free on its surface and had excellent gloss . The film showed a hardness (Shore D) of 77 to 78 and excellent adhesion to the substrate.

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Example 3:

A composition having a viscosity of 5 centipoise 1OO was obtained at 25 ⁰ C by homogeneously mixing the following ingredients:

94 parts of a dimethylpolysiloxane of the formula

Me I

Vi- Si — 0-

Me

f ^Me \
-Si-O-

Me

Si-Vi

\ Me / 450 Me

with a viscosity of about 5,000 centistokes measured at

6 parts of an organopolysiloxane consisting of 1.0 mol S10_ units, 0.05 mol ViMeSiO units, 0.044 mol Me ₂ SiO units, 0.1 mol ViMe ₀ SiO, - ^ units and 0.7 mol Me, SiO_ _- Units;

1.9 parts of a methyl hydrogen polysiloxane of the formula

Me I.

H — Si — ΟΙ Me

\ Me

Si-O-) k-Si-0

Me

/ 8 \ ϊ

Me I -Si-H;

10 Me

1.0 part of the epoxy group-containing organohydrogenpolysiloxane according to example 2;

1.0 part of titanium dioxide, 0.025 parts of the same solution of Chloroplatinic acid in butanol as in Example 1;

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Kieselguhr (fumed)
0.5 part of a filler, the surface of which has been treated with trimethylchlorosilane and a specific area of
about 2OO m / g

and 0.5 part of an organopolysiloxane containing alkynyloxy groups the formula

The composition was left at 150 ° C for four hours
held. A product was obtained which was free of creases on the surface and had a good gloss and the following properties:

Hardness (JIS) : 24 Elongation to break (%) : 180 Tensile strength (kg / cm ² ) : 5.9 specific resistance
(ohm-cm) : 1.0 χ 10 Dielectric strength
(kV / mm) : 23 Dielectric constant
(50 HzI : 2.9

After that, the composition was kept at 25 C for three months.

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was ten, their viscosity increased to 7.O0O centipoise while a mixture of the same composition but without the alkynyloxy group-containing organopolysiloxane gelled after one hour at 25 ⁰ C.

Comparative experiment:

As can be seen from Example 1, Experiment 2 was satisfactory Results obtained wherein the alkynyloxy group-containing organopolysiloxane was prepared by that one is an organohydrogenpolysiloxane of the formula

reacted with 1.1 dimethylpropargyl alcohol Hca C-CMe-OH in toluene in the presence of sodium methoxide NaOMe, followed by neutralization of the reaction mixture with trimethylchlorosilane and complete removal of the solvent and the low-boiling compounds by heating at 12O ° c under reduced pressure at 2 ranilg for 8 hours.

For comparison purposes, the removal of the solvent and the low boiling compounds by heating at 1OO ⁰ C at 3 mmHg for the same duration tent was again executed. The resulting product was used as a stabilizer, ie as component (d) in the same amount in the

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Composition of experiment 2 used. A cured one was likewise obtained with the resulting mixture Product. However, many wrinkles were observed on the surface of the same product.

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Claims (9)

PATENT CLAIMS 1. Curable organopolysiloxane composition with an organopolysiloxane with at least two vinyl groups bonded directly to the silicon atoms of a molecule, an organohydroqenpolysiloxane with at least two hydrogen atoms bonded directly to the silicon atoms of a molecule and a platinum catalyst, characterized in that the (a) Organopolysiloxane has the following average unit formula (CH ₂ -CH) where R is the same or a different monovalent hydrocarbon group without aliphatically unsaturated ones Remainder, a denotes a value from 0, 000025 to 0.5 and b has a value from 0.75 to 2 with the proviso that the sum of a and b is 1.25 to 2.25, (b) Organohydrogenpolysiloxane, which is not aliphatically unsaturated Has radicals, is provided in such an amount that 0.5 to 4 hydrogen atoms directly to the silicon atoms per vinyl group are provided in component (a) and that the composition 709831/0928 (d) an alkynyloxy group-containing organopolysiloxane which in one molecule at least a monovalent hydrocarbon group with a -CsC bond, which via an oxygen / silicon bond to the Silicon atom is connected, has. 2. Composition according to claim 1, characterized in that the amount of the platinum catalyst is at least 0.05 ppm by weight based on the total weight of components (a) and (b) and that the weight of component (d) is such that two to 10,000 moles of the -C = C bonds are present per mole of platinum atoms in the platinum catalyst. 3. Composition according to claim 1, characterized in that the boiling point of the component (d) is greater than 25O ⁰ C. 4. Composition according to claim 1, characterized in that more than 3O mol% of the siloxane units of the component (d) are those having alkynyloxy groups attached thereto. 5. Composition according to claim 1, characterized in that the alkynyloxy group has three or more carbon atoms. 6. Composition according to claim 1, characterized in that 709831/0928 that component (d) has a linear molecular configuration with less than 100 silicon atoms per molecule. 7. Composition according to claim 6, characterized in that a silo unit with the alkynyloxy group bonded to it is arranged centrally between the ends of the molecular chain. 8. Composition according to claim 1, characterized in that the alkynyloxy group is a 1,1-dimethylpropynyloxy group. 9. Composition according to claim 1, characterized in that the alkynyloxy group is a 1-methyl-1-ethylpropynyloxy group. 709831/0928