DE2632294C2 - Silyl ethers and their use as polymerization initiators - Google Patents

Description

R ¹ methyl, ethyl, phenyl, benzyl, chloromethyl, R ^: hydroxyl, methoxy, ethoxy, R ¹ or A, R- 'hydroxyl or A,

R ⁴ , R 'optionally _{substituted by C 1} to C-alkyl, methoxy, chlorine or fluorine phenyl, naphthyl or biphenylyl radicals,

R ''. R either R ⁴ or R ^ or optionally substituted by C 1 to C 4 alkyl, methoxy, chlorine or fluorine substituted alkyl radicals with 1 to 6 carbon atoms, cycloalkyl radicals with 5 to 7 carbon atoms and hydrogen,

R ^{s is} hydrogen or a silylresl of the formula II

R ¹

-Si-A

R ^:

and A is a radical of the formula IH R ⁴ R ~

I!

- O - C - C - O - R ^s R "R"

(II)

(Ul)

mean, where the compounds of the formula I have the substructure IV

R ⁴ ir
--ο —c —c —o -

R "R"

(IV)

one to twenty times enthulu η can, available by reacting 1 mole of an aryl clone or an arylaid cover of the formula V or VI

W - C - R "

I! ο

W- CHO

(V)

(VI)

R 'Lind R "has the meaning indicated above, and about an equivalent amount of a metal of the" 1st or 2nd main group of the periodic table in an inert aprotic solvent or Lösungsmittelgemiseh at -10 to +70 ⁰ C

with 0.4 to 0.8 months! of a dichloroorganosilane of Formula VII

R ¹ R- ¹ SiCI,

(VII)

or with 0.25 to 0.6 mol of a trichloroorganosilane of the formula VIII

P ¹ SiCl ₃

(VIII)

Hydrolysis and separation of the organic phase and removal of the solvent at 20 ^° C. and a pressure between 266 and 800 Pa, where R 'has the meaning given above and R ^: ' for the same substituents as stated above for R ^: but A and hydroxyl are excluded - stands.

2. Use of the silyl ethers according to claim 1 as initiators for polymerisalion reactions which can be initiated by free radicals.

The invention relates to silyl ethers, which by Umselzung base metal with α-aryl ketones or aryl aldehydes and di- or trichloroorganosilanes are available, and their use as initiators for free radicals initiable polymerization reactions.

From DF-AS 12 16 877 and 12 19 224 and from DE-OS 21 31 623 and 21 64 482 it is known that themselves l.l ^^ - Tctraaryl-l ^ -dihydroxyethane, their alkyl and silyl ethers are suitable as initiators for radical polymerization reactions. They are - as opposed to the well-known peroxide catalysts - completely safe to handle. The curing is free-radically polymerizable Substances in the presence of these initiators can be controlled easily and safely by temperature control will.

DE-OS 21 31 623 relates to a process for polymerization radically polymerizable Monomercr in the presence of Glykoldisilylcthern, such as. B. Benzpinakoldisilylcthcrn (see Examples 1-11 and 17). These initiators are free from the disadvantages of peroxidic radical formers, however, cannot meet all requirements with regard to high reactivity.

Surprisingly, it has now been found that the reaction of base metals, preferably metals of main groups 1 and 2 of the periodic table, in particular lithium, sodium, potassium, magnesium or calcium, with σ-aryl ketones or aryl aldehydes and di- or trichloroorganosilanes in one inert aprotic solvent and subsequent hydrolysis leads easily and in very high yield to silyl ethers which, even in low concentrations, sometimes cause the substances to be polymerized to cure quickly and completely ^{at temperatures from 40 ° C.}

In addition, polymerizable systems with a content of silyl ethers according to the invention are notable characterized by a relatively high storage stability. Another advantage of the initiators according to the invention is it is that when they break down into radicals they do not release any volatile substances, which are undesirable in the polymer Can cause blistering.

The invention relates to silyethers with a number average molecular weight of 500 to 5000 of the formula I.

R'R-'SiCl,

(VII)

R ¹ R ⁴ R ⁵

R ¹ - Si - O - C - C - O - R ⁸
R ³ R ⁶ R ⁷

wherein

R ¹ methyl, ethyl, phenyl, benzyl, chloromiethyl, R- ¹ hydroxyl, methoxy, elhoxy, R ¹ or A.

R ¹ hydroxyl or A,

R ⁴ , R ~ phenyl, naphthyl or biphenylyl radicals optionally substituted by C 1 to C 1 alkyl, melhoxy, chlorine or fluorine,

R '', R ⁷ either R ⁴ or R ^ or optionally _{substituted by C 1} - to Q-alkyl, methoxy, chlorine or fluorine substituted alkyl radicals with 1 to 6 carbon atoms, cycloalkylresle with 5 to 7 carbon atoms and hydrogen,

R ^{K is} hydrogen or a silyl radical of the formula II

R ¹
- Si —A

R ²
and A a res! of formula III

R ⁴ W

- O - C - CO - R ⁸
R ⁶ R ⁷

(Hl)

mean, where the compounds of the formula I have the substructure IV

R ⁴ R ⁵
- O —C —C —O-

R "R ⁷

(IV)

Can contain one to twenty times, obtainable by reacting 1 mol of an a-aryl ketone or one Arylaldehyde of the formula V or VI

R ⁴ -C R ⁶

Il ο

R ⁴ -CHO

(V)

(Vl)

wherein

R ⁴ and R ″ have the meaning given above, and approximately the equivalent amount of a metal of the 1st or 2nd main group of the periodic table in an inert aprotic solvent or solvent mixture at -10 to +70 ⁰ C with 0.4 to 0.8 mol of a dichloroorganosilane of the formula VII or with 0.25 to 0.6 mol of a trichloroorganosilane of the formula VIII

R ¹ SiCI,

(VIII)

Hydrolysis and separation of the organic phase, and removal of the solvent at 20 ° C and a pressure between 266 and 800 Pa, where R 'has the meaning given above and R ² ' for the same substituents as given above for R ² - but A and Except for hydroxyl - stands.

The invention also relates to the use of the silyl ethers according to the invention as initiators for polymerization reactions that can be initiated by free radicals.

The molecular weight of the silyl ethers according to the invention is up to a molecular weight of 3000 vapor pressure osmometric, with a molecular weight above 3000 membrane osmometric, in each case in Acetone as a solvent. The molecular weights of individual fractions of the invention The reaction mixture can be determined by gel chromatography (using calibration substances).

As examples of the aldehydes or ketones and silanes to be used as starting materials, im the following listed various reactants for the preparation of the silyl ethers according to the invention, the in turn as initiators for polymerization reactions that can be initiated by free radicals are effective.

magnesium

magnesium

magnesium

magnesium

sodium

magnesium

lithium

8) magnesium

15)
16)
17)
18)
19)
20)

magnesium
magnesium
sodium
lithium

potassium
Calcium

magnesium

sodium

magnesium

magnesium

magnesium

magnesium

magnesium

Benzaldehyde

Benzaldehyde

Benzaldehyde

Acetophenone

Acetophenone

Propiophenone

Isopropyl

phenyl ketone

Cyclohexyl

phenyl ketone

Benzophenone

Benzophenone

Benzophenone

4,4'-dimethyl

bcnzophenon

Benzophenone

4-t-butylben-

zophenon

4-chlorobenzo

phenone

2-methylbene

zophenon

2-chlorobenzo

phenone

2,4-dichloro

benzophenone

3-methoxy

benzophconon

Naphthyl

phenyl ketone

4-phenylben-

/ ophenon

Trichloromethylsilane

Trichlorophenylsilane

Dichlorodimelhylsilane

Trichloromethylsilane

Diphenyldichlorosilane

Trichloromethylsilane

Trichloromethylsilane

Trichloromethylsilane

Trichloromethylsilane dichlorodimethylsilane trichlorophenyisilane Trichloromethylsilane

Dichlorodiphenylsilane trichloromethylsilane

Trichloromethylsilane dichlorodimethylsilane Trichloromethylsilane Trichlorocthylsilane

Dichloroethoxy

methylsilane

Trichloromethylsilane

Trichloromethane silane

Inert aprotic solvents are /. B. Flavors and alkyl ammals such as benzene and toluene. Ethers such as diethyl ether. Diisopropyl heron. Dibutyl ether. Anisole. Tetrahydrofuran. Dioxane. 1.2-Dimethoxvelhan. Trial

alkyl phosphates such as triethyl phosphate, tributyl phosphate; Ν, Ν-disubstituted amides such as dimethylformamide, Ν, Ν-dimethylacetamide and phosphoric acid tris (dimethylamide). Further suitable solvents are in "Methods of Organic Chemistry" (Houben-Weyl), Vol. X1II / 2a, pp. 59-70, Georg Thieme-Verlag, Stuttgart 1973, described. As particularly suitable Solvent mixtures of 0 to 80 parts by weight of benzene or toluene and 2 to 98 parts by weight have been found Tetrahydrofuran and 2 to 98 parts by weight of triethyl phosphate or phosphoric acid tris (dimethylamide). To that Not to dilute the reaction mixture unnecessarily, as little solvent as possible is generally used. Usually it is the keto compound / solvent weight ratio of 1: 1 is completely sufficient.

It is advisable to take into account that partial decomposition under the reaction conditions is possible. So if the silyl ethers according to the invention should have a low reactivity, which is based on decomposition the compounds that are active as initiators are to be returned during the preparation, is recommended a decrease in the reaction temperature.

The silyl ethers according to the invention are distinguished by their high reactivity. So they outperform the connections according to DE-OS 2131 623 considerably in terms of their reactivity.

Some of the silyl ethers according to the invention are already effective at temperatures above 40.degree. One Complete and rapid through-hardening is generally achieved when 0.02 to 1, preferably 0.05 to 0.8 % By weight, based on the substance to be polymerized, achieved.

The start of the polymerization reaction is achieved by heating a mixture of substance to be polymerized and silyl ethers according to the invention via a specific, easily determined in individual cases Light-off temperature, reached. The curing of radically polymerizable systems usually takes place between 60 and 200 ° C.

Hardening can take place in one go, if desired in stages (see GB-PS 10 41 641).

It is possible through a simple color reaction to die Determine the light-off temperature of the initiator reaction mixtures according to the invention: that of the thermal This is because radicals formed by decomposition can discolor quinoid dyes. To carry out the test dissolves a small amount of quinoid dye, e.g. B. Methylene Blue. Thionin, or Neutral Red, in a solvent free of molecular Is oxygen, e.g. B. glycol, xylene, and uses an at least equivalent amount of the invention Reaction mixture too. The temperature at which the dye is discolored is the light-off temperature of the Initiator reaction mixture.

The light-off temperature depends heavily on the structure of the compounds according to formula I. Initiators with many space-filling (e.g. aryl) radicals are distinguished (especially in the case of ortho-substituted aryl radicals) by a relatively low light-off temperature; Initiators in which R ⁶ and R ⁷ stand for alkyl groups or f hydrogen do not disintegrate until higher temperatures and are possibly still stable in the substance to be polymerized up to 8 () ° C.

As substances whose polymerization may be initiated by the erlindungsgcmäßen silyl ethers' are all free-radically polymerisierbarcp compounds or mixtures of these, for example. B. So conjugated dienes such as butadiene. Isoprene. Chloroprene; Vinyl chloride, vinylidene chloride; aromatic vinyl compounds such as styrene, divinyibenzene; Vinyl esters, especially vinyl acetate and vinyl propionate; Vinyl ethers such as vinyl propyl ether, vinyl isobutyl ether; Acrylic acid and methacrylic acid and their derivatives such as esters, in particular with aliphatic alcohols having 1 to 5 carbon atoms, nitriles, amides, etc .; Di (vinylphenyl) carbonates; Diallyl phthalate, diallyl carbonate, diallyl fumarate; Di (allylphenyl) carbonates; Polyo! -Poly (meth) acr / late; N, N'-methylene) bis (meth) acrylamide.

Particularly suitable substances for initiating polymerization with the silyl ethers to be used according to the invention are unsaturated polyester resins, d. H. the solutions σ ^ -ethylenically unsaturated poly- ■> ester in monomers copolymerizable therewith.

Suitable ff ^ ß-ethylenically unsaturated polyesters are the usual polycondensation products with at least one c ^ -ethylenically unsaturated dicarboxylic acid usually 4 or 5 carbon atoms or their ester-forming derivatives, e.g. B. their anhydrides, optionally in Mixture with up to 200 mol%, based on the unsaturated acid components, at least one saturated aliphatic with 4 to 10 carbon atoms or a cycloaliphatic dicarboxylic acid with 8 to 10 > C atoms or their ester-forming derivatives with at least: a polyhydroxy compound, in particular Dihydroxy compound, with 2 to 8 carbon atoms - a'so polyester, as described in J. Björksten et al., »Polyesters and their Applications ", Reinhold Publishing Corp., New York 1956.

Examples of unsaturated dicarboxylic acids or their derivatives that are preferably to be used are maleic acid or maleic anhydride and fumaric acid. Can be used, for. B. but also mesaconic acid, citraconic acid, Itaconic acid or chloromalemic acid. Examples of the aliphatic saturated to be used and cycloaliphatic dicarboxylic acids or their derivatives are phthalic acid or phthalic anhydride, Isophthalic acid, terephthalic acid, hexa- or tetrahydrophthalic acid or their anhydrides, endomethylenetetrahydrophthalic acid or their anhydride, succinic acid or succinic anhydride and succinic acid ester and chlorides, adipic acid, sebacic acid. In order to produce resins which are difficult to ignite, e.g. B. Hexachlorendomethylenetetr ^ hydrophthalic acid (Hetsäure), Tetrachlorophthalic acid or tetrabromophthalic acid can be used. As dihydric alcohols ethylene glycol, 1,2-propanediol, 1,3-propanediol, Diethylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, neopentylglycoKhexanediol-Uo ^^ - bis (4-hydroxycyclohexyl) propane, bisoxalkylated bisphenol A, perhydrobisphenol and others can be used. Ethylene glycol, 1,2-propanediol, Diethylene glycol and dipropylene glycol.

Further modifications are possible by incorporating mono-, tri- and tetravalent alcohols with 1 to 6 carbon atoms, such as methanol, ethanol, butanol, allyl alcohol, benzyl alcohol, cyclohexanol and tetrahydrofuryl alcohol, Trimethylolpropane, glycerol and pentaerythritol as well as mono-, di- and triallyl ethers and benzyl ethers trihydric and polyhydric alcohols with 3 to 6 carbon atoms according to DE-AS 10 24 654, and by Eintvu monobasic acids such as benzoic acid, or long-chain unsaturated fatty acids such as oleic acid, I. and ricinic fatty acid.

The acid numbers of the polyesters are usually between 1 and 100, preferably between 20 and 70, the OH number between 10 and 150, preferably between

see 20 and 100, and the molecular weights M ₁₁ determined as / ahlenmillel between approx. 500 and 5000, preferably between approx. 1000 and 3000 (measured by vapor pressure osmometry in dioxane and acetone; if the widths differ, the lower than the correct one is measured).

As copolymerizable with the unsaturated polyesters Vinyl and vinyl dcn compounds are unsaturated which are customary in polyester technology Compounds which prefer (/ -substituted vinyl groups carry or i-substituted allyl groups, preferably styrene; but also, for example, nuclear chlorinated and -alkylated or -alkenylated styrenes, the alkyl groups May contain 1 to 4 carbon atoms, e.g. B. vinyltoluene, divinylbenzene, tf-methylstyrene, tert, -Butyistyroi, Chiorsiyroie; Vinyl esters of carboxylic acids having 2 to 6 carbon atoms, preferably vinyl acetate; Vinyl pyridine, vinyl naphthalene, vinyl cyclohexane, acrylic acid and methacrylic acid and / or their esters (preferably Vinyl, allyl and methhallyl esters) with 1 to 4 carbon atoms in the alcohol component, its amides and nitriles, maleic anhydride, half and diesters with 1 to 4 carbon atoms in the alcohol component, half and diamides or cyclic imides such as N-methyl maleimide or N-cyclohexyl maleimide; Allyl compounds such as allylbenzene and allyl esters such as allyl acetate, diallyl phthalate, diallyl isophthalate, Fumaric acid diallylesler, allyl carbonals. Diallyl carbonate, triallyl phosphate and triallyl cyanurate.

The following examples illustrate the invention.

The parts given below are parts by weight and percentages are given as percentages by weight.

A. Manufacture Example 1

24 g of magnesium and 364 g of benzophenone are placed in a solvent mixture of 500 parts of toluene, 100 parts of phosphoric tris (dimethylamide) and 50 parts of tetrahydrofuran. At a temperature of 25-40 ⁰ C are slowly added dropwise llOgTrichlormethylsilan, wherein the magnesium dissolves completely. After stirring for 4 hours at 30 ^° C., the batch is poured onto 1 l of ice. The organic phase is washed a few times with water and then ^{concentrated at 40 °} C. in a water jet vacuum. A highly viscous liquid remains as the residue, which solidifies to a glass-like solid after standing for a long time.

The gel chromatography was carried out with a low-molecular-weight column combination filled with Styragel different pore sizes (Waters measurement technique) carried out; tetrahydrofuran was used as the eluent used. The calibration was carried out with benzophenone, acetophenone and benzpinacol. Correlated with the following molecular weight distribution results.

component

idit ll.icliL'nprn / enl

1400
1700
2100
2460

\ ln (osnmmetiischi: U (II).

3 1.0

29.0

15.7

6.8

Example 2

Example 1 is modified: instead of benzophenone 240 g of acetophenone are used. A solid iiaiz remains after work-up.

(jelchroinatographic:

component Molecular weight Area pro / ent I. 120 2.5 2 242 1.9 3 700 7.5 4th 980 28.7 5 1800 38.0 6th 2400 13.2 7th 3600 8.2

Example 3

In a solvent mixture of 250 ml of abs. Tetrahydrofuran and 50 ml of triethylpliosphate, 23 g of sodium are pressed into threads. At -5 to 10 ^0. C. to dropwise a solution of I96g2-methylbenzophenone and 66 g of dichlorodimethylsilane in 200 cc of abs. Tetrahydrofuran. When the sodium has completely dissolved, the mixture is stirred for a further 3 hours and the batch is then hydrolyzed with 600 g of ice. After washing several times with ice water, the organic phase is concentrated at 20 ° C. in a water jet vacuum.

Gel chromatography:

component Molecular weight Area percentage , ι 450 0.8 2 470 5.0 1
J innn 33.5 4th 1450 25.4 5 1900 24.1 5 6 2700 11.0

The silyl ethers used in the examples below were taken from the reactants the table (pages 5 and 6) prepared analogously to Examples 1-3.

component

Molecular weight

Area percentage

1 182 1.4 2 366 5.2 3 '520 2.3 4th 940 8.4

B. Use
Example 4

An unsaturated polyester resin made from 11 parts of phthalic anhydride, 47 parts of maleic anhydride

hydride and 42 parts of 1,2-propylene glycol at 200 ° C (acid number 20. Oll number 30, viscosity at 20 ° C: 150 (1 ep), 66 "is dissolved in styrene, stabilized with 0.01 part of hydroquinone and with .3 Parts of the initiators 2, 4, 8, 9, 14, 16, 17 (cf. pages 5 and 6) Benzpinakoldi-urimethylsilyleiher) (cf. DH-OS 21 31 623, hereinafter referred to as “BPDSH” for short) or mixed benzpinacol. Kine One hour after the addition of the initiator, 20 g of an Iarzansatz.es are filled in a test tube 16 mm in diameter. Hin Hisen constantan thermal element, which is connected to a temperature-time recorder, is immersed 3 cm in the resin and the test tube, filled to 8 cm, is placed in a thermostatic oil bath after the measuring device has been switched on. Analogue to D! N 16 945, the curing lines / ,, (time until the peak temperature is reached minus the line until the 65 ° C line is exceeded) and the Peak temperature Cl ',, ) determined.

With the indicated Budlempcruturen result the following values:

ie

O U-) CC:
On On - rs
- - rs oj

Λ Λ

160 ON 210 235 250 rs r ~ j rs Λ Λ Λ 14.4 On ro _r rs
ro ' OO
rs rsi 175 190 210 235 OSZ 250 OSZ Λ Λ Λ rs
rs' 8.0 rs,
ro rs' rs' ON 190 225 250 OSZ OSZ 250 OSZ Λ Λ Λ Λ Λ 13.0 OO 4.9 ro " OO
rs' rs
CN On 190 215 240 OSZ OSZ OSZ OSZ Λ Λ Λ Λ 14.2 On ' ίο OO
rs rs
rs' On 061 OZZ OSZ OSZ 250 250 250 Λ Λ Λ Λ O O
On " ro OO rs On

O
OO O
ON rs l / ~ l
ro
rs 250 250 250 Λ Λ OO OO ro ro QO OO Tj- ro rs 220 240 OSZ O
UO
rs Λ "~ i O
UO OO
ro rs
ro ' 230 245 O
UO
rs 9.0 2 O
UO O 100 O 120 O
ro 140

Il

Example 5

Heispiel 4 is repeated with the modification clal.i the initiators with the 2, 4, are stored 8,9, 12, 14 and BPDSE abgemisL'liten llarzansätze for four days at 60 ⁰ C prior to curing. The measurements subsequently carried out did not reveal any changes in the spit / duck temperatures and the hardening times when initiators 2, 4, 8, 9, 12 and 14 were used; those with BPI) SE

Mixed approaches were already after 12 hours gelled.

Example 6

Example 4 is repeated with the difference that the initiator used is mixtures of benzyl peroxide and the initiator 9 can be used.

The curing time (min.) And the maximum temperature I ₁₁ ( ⁰ C) are determined.

Initiator mixture Bud temperatures

Share parts 4 80 ⁰ C

IVroMtl ι α! ', "

90 ° CK) II ⁰ C

L,

1 HFC

0.15 0.1 15th _ 10.5 225 5.5 250 3.4 > 25O 0.15 0.3 10 210 6.0 240 4.0 > 25O 2.8 > 250 0.15 15th 215 5.1 240 3.2 > 25O τ τ > 25O 0.25 0.1 13th 210 7.5 235 4.5 > 25O 2.8 > 25 () 0.25 0.3 9 215 4.8 245 3.5 > 25O 2.3 > 25O 0.25 10 225 4.0 > 25O 2.7 > 25O 1.9 > 250 0.5 0.1 8th 220 4.8 245 3.2 > 25O > 250 0.5 0.3 7th 228 4.0 > 25O 2.7 > 25O 2.0 > 250 0.5 6th 235 3.5 > 25O 2.3 > 25O l.S. > 250 1.0 0.1 5 235 3.4 250 2.6 > 25O 1.6 > 25O 1.0 243 2.3 > 25O 1.9 > 25O 1.5 > 250

Example 7

33.3% solutions of butyl acrylate in toluene are each with 0.1 part of initiators 9, 10 (see. Page 5), BPDSE or benzpinacol are added and the mixture is heated to the specified temperature in several portions of 30 g each.

L Samples are taken after certain times.

I, which with 1 ml of a 4% solution of hydroquinone in

Added ethyl acetate and then in an open dish

I _{I be} poured. The solvents are; evaporated [16stündiges heating to 100 ⁰ C and the remainder monomeric by annealing of the residue at 16Ü ^U C in a vacuum drying cabinet 200 Torr).

The gravimetric determination of the residues gives the following proportions of polymerized substance (% the initial weight):

Polymerization temperature: 100 ⁰ C Polymcrisationslemperatur: 120 ° C

initiator

Polymerisation time (min)

15 30 60 120 240

Benzpinacol
Initiator 9
Initiator 10
BPDSE

26th
35
28
28

41
60
54
54

51
84
76
75

87 96 91 80 initiator

Polymerization / eii iniin)

15 30 60 120 240

Benzpinacol
Initiator 9
Initiator 10
BPDSE

Polymerization temperature: 140 ° C

15th 33 58 75 96 27 48 72 84 99 24 42 68 V. 97 27 51 74 85 94

initiator

Polymerisation time (min)

15 30 60 120 240

Benzpinacol
^b0 initiator 9
Initiator 10
BPDSE

100 parts of styrene are mixed with 0.2 parts of an initiator and placed in a thermostatically controlled oil bath

21 38 59 77 97 31 60 96 98 99 30th 62 88 94 99 38 70 84 92 95 example 8th

80 ⁰ C or IHPC "polymerized. The reaction * is washed with methanol and then im

after a certain period of time by cooling the solution, yakiiiimlnekenschrank overnight at 6 () ° C

aborted and the polymerized styrene by Yernet.

The following amount of polymerized styrene should be made thin with the lünlTachen volume of methanol

slurped. ■ preserved (\ polystyrene). After 1 hour, the polymer is filtered off with suction,

Polymerization temperature: 80 ^{0 C}

Initiator polymerization / eil (mini

30 60 120 240

Initiator 9 0.7 3.8 10.0 17.3 Initiator 10 2.5 7.0 14, η 20.2 BPDSi: 3.0 6.2 11.5 19.0 Benzpinacol - - 0.2 0.4 Without initiator - _ - -

Polymerization temperature: 110 ^{0 C}

Initiator polymerisation time (min)

10 15 20 30

Initiator 4 0.3 1.4 3.4 9.6 Initiator 9 8.5 14.7 24.3 37.8 Initiator 10 8.8 15.0 22.8 34.5 BPDSE 6.0 17.0 25.0 32.5 Benzpinacol 0.9 2.8 8.9 24.8 Without initiator - - - 0.3

Claims (1)

Patent claims: 1. Silyl ethers with a number average molecular weight of 500 to 5000 of the formula I. R ¹ R ⁴ R ⁵ R - Si - Ο - C - C - O - R "R ³ R ⁶ R ⁷ (D