DE2208149B2 - Process for the production of polyether urethane foams - Google Patents

Description

R ² O-

R ¹

Si —O -

M.
POA

CH,

Si —O -

CH ₃

R ¹

Si-OR ² M POA

is used, in which m is uniform in segments or approximately uniform in segments = 5 or 6 or the index m is between 4 and 7, whereby the number of segments of the index 5 and 6 is at least twice as large as the number of segments of the index 4 and 7, n> 2, R ^{1 is} a saturated alkyl radical with 1 to 8 carbon atoms, R ^{2 has} the meaning of the radical R ¹ or the groups = POA or R \ Si-, M represents oxygen

or an alkylenoxy radical having 1 to 3 carbon atoms, a

-CH ₁ -CH-CH ₂ -O

CH ₃

- (CH ₂ J ₁₀ -CO

ίο

-CH ₂ -CH-C-O group

R ³ O

15th

with R ³ = H or CH ₃ - in which the carbon atom is linked to the silicon atom and the terminal oxygen atom is linked to the polyoxyalkylene group, and POA is a radical terminated by an alkyl radical with 1 to 8 carbon atoms or a phenyl radical with polyoxyethylene and polyoxypropylene units in the weight ratio of 50:50 to 30:70 and having a block molecular weight of 1,400 to 3,000

The essence of the present invention consists in the fact that the dimethylpolysiloxane blocks are uniform in segments, the respective segment being determined by the index m = 5 or 6. segment-like blocks are used where the index m is between 4 and 7 but has a focus at 5 and 6, r, where the number of segments of the index 5 and 6 is at least twice as large as the number of segments of the index 4 and 7. This can be illustrated using the molecular weight distribution curve, which normally appears in the form of a wide flat curve (Gaussian distribution), but here corresponds to a correspondingly narrow section with a narrow base and greater height.

The fact found according to the invention that precisely such foam stabilizers with segmental, uniform or approximately segmental (= segment-like) dimethylpolysiloxane residues show an outstanding effect, contradicts general experience, since especially when surface-active substances are used, mixtures of compounds of different fertilizers Chain length have better properties than the relatively pure substances. There was thus a prejudice against the use of the compounds to be used according to the invention. v>

Del polyoxyalkylene block (POA) has a molecular weight of 1400 to 3000. The optimum molecular weight depends on both the Foaming used starting substances as well as according to the process conditions. Especially «> a range from 1600 to 22000 is preferred. Of the Polyoxyalkylene block is composed of polyoxypropylene and polyoxyethylene units in a weight ratio from 50:50 to 70:30 together. This polyoxyalkylene block is replaced by an alkyl radical with 1 to 8 h "> Carbon atoms or a phenyl radical.

In the polyalkylene glycol polysilo? in-block mix-

lymerisat, the radical R 'is preferably a methyl radical, but other saturated alkyl radicals with 2 to 8 carbon atoms, which can be present alone or in a mixture, preferably with the methyl radical, are also possible. The same applies to the radical R ² , if it has the meaning of the radical R <, ^{however, if R 2} has the meaning of the group -POA, then the statements made for this also apply here. The group R ² , however, as a chain-terminating end member, can also represent the grouping R] -Si-, for example the grouping (CHa) ₃ Si, but the radicals R ^{1 can} also have the further meaning given for R '.

The group M represents the link between each silicon atom and the polyoxyalkylene structure. Sit has the meaning of an oxygen radical, but can also mean an alkyleneoxy radical with 1 to 3 carbon atoms. It is known to those skilled in the art that Block copolymers in which the silicon atom with the polyoxyalkylene radical via an alkyleneoxy radical is more stable to hydrolysis than those in which the polyoxyalkylene radical is connected to the via oxygen A silicon atom is linked, but this is of less importance in practice

-CH ₂ -CH-CH ₂ -O

CH ₃ - (CH ₂ J ₁₀ -CO

- CH ₂ - CH - C - O group

's " R ¹ O

mean, where the carbon atom is linked to the Siüciumatom and the terminal oxygen atom to the polyoxyalkylene ^{group. R 3 here} has the meaning of a hydrogen radical or a methyl group.

The production of such foam stabilizers to be used according to the invention and in particular of the uniform segment polysiloxane residue can be done in the following way:

1. Synthesis of

HO -

CK ₃

Si —O -

CHj

H:

Leave the polydimethylsiloxane diols of the formula mentioned used as starting materials easily synthesize by hydrolysis of the corresponding Λ, ω-dichloropolydimethylsiloxanes the formula

V ^. I.

CH ₃

CU,

O— YOURSELF,

Cl

in an aqueous medium, which by adding acid acceptors, such as amines, and strong

Stirring during the reaction is prevented from forming locally strong concentrations of hydrochloric acid. The polydimethylsiloxane diols formed can, if necessary, be distilled again in the column under reduced pressure in a well washed state.
Z Synthesis of compounds of the formula

R ¹

X-Si-X
M.

POA

X = group reactive towards SiOH, preferably chlorine or

CH ₃ -C — O -

These silanes can be produced by using olefinically end-capped polyethers, such as. B. Polyethers with terminal allyl groups on silanes of the formula

Adds hydrosilatingly, for example using platinum catalysts. This creates silanes in which the polyether block POA is connected to the silicon atom via an alkyleneoxy group. is reacted with silanes of the formula R ¹ —Si —X3, these silanes being used in a very large excess and the excess being removed by distillation after the reaction.
3. The polyalkylene glycol-polysiloxane block copolymers which can be used according to the invention can now be prepared by introducing the silanes listed under 2. and adding dropwise a mixture of the polydimethylsiloxanediols and tert-amines listed under 1. with thorough stirring Appropriate solvents, as well as dissipation of the heat of reaction by cooling. One uses λ + 1MoI of the silanes mentioned under 2. to π moles of the polydimethylsiloxanediols mentioned under 1., the latter in a mixture with 2η + 2 moles of tert-amines, it being advantageous to use the latter in a certain excess. Beifn conversion of the silanes with the Polydin'ethylsilojiandiolen shown in the molar ratio art ¹ residue at X-groups is initially unumgtfsetzt. Diener rest is thereby give to the reaction at the end ^r eight, that the reaction? Emic ^v erbint'jn55en of the formula R ² OH is added, wherein again is thus guaranteed a certain Qberschuß is indicated that the split off during hydrolysis acid SiX groups must be completely removed. After the reaction, the salts are filtered off and the products according to the invention are finally obtained by distilling off excesses - as far as possible - together with the inert solvents used

The improved foam stabilizer properties of the polyalkylene glycol-polysiloxane block copolymers to be used according to the invention are shown in particular in the fact that smaller amounts of foam stabilizers than is possible according to the prior art are usually used in the production of such foams to adequately stabilize the polyether urethane foam as 0.5% by weight of stabilizers, based on the mixture to be foamed. In accordance with the invention verwenc ¹ · ten foam stabilizers often been an addition of 0.1 wt .-% is sufficient.

In the following, the subject matter of the present invention will be explained in more detail Production of the foam stabilizers to be used according to the invention which is not claimed is shown in the example 1 shows foaming tests with the foam stabilizers to be used according to the invention a comparative experiment proving that it is possible with the foam stabilizers to be used according to the invention

jo ren succeeds with much smaller amounts of Stabilizers to make good foams. Another comparison test shows the superior effect of the stabilizers prepared by the process according to the invention versus stabilizers according to US-PS 35 07 815.

production method

for those in the method according to the invention

used stabilizers

a) Preparation of the siloxanes of the formula

Cl-

CH ₃

-Si-O-CH ₃

CH ₃
-Si-Cl

I.
I.

CH ₃

These products are made by very careful fractional distillation of a deficiency hydrolysis Mixture obtained from dimethyldichlorosilane produced on the column. The purity of the products is determined by gas chromatography checked

Table 1 shows the boiling points and the purity determined by gas chromatography:

Tabel 1 mm
mm
mm
mm
mm "/.-Salary,
gas chromatography
does not contain m boiling point 97.5
98
93.5
94
98 4th
5
6th
7th
9 105X715
L-rC / 15
154 XV15
145 C / 3
176 CV 3

b) Preparation of the siloxane of the formula

HO

CHj

-Si-O-CH ₃

The synthesis of these products takes place according to a procedure which is outlined below: 1 mol

Cl-

CH,

-Si-O

CH,

_L

C H,

-Si- Cl

CH,

is in four times the amount by weight CHjCI ,. solved. This solution is added dropwise within 2 hours to a mixture of 177.3 g (3 mol) of isopropylamine and as much H2O as Ut corresponds to the amount by weight: ~> of CH2Cl2. It is stirred vigorously and cooled so that the temperature of the reaction mixture does not exceed 35.degree. It is then neutralized with 25% acetic acid, the aqueous phase is separated off and the organic phase is washed at least five times with distilled water. The CH2Cl2 is added to a bath temperature of 5O ⁰ C and a vacuum of 12 mm distilled off. The following table 2 contains the purity grades of the products and the found OH value:

Table 2

m 'content OH content in%> n

practically theoretically

97.8
98.3
97.9
93.7
98

10.5
8.6
7.2
5.9
4.85

10.8
8.75
7.35
6.3
4.95

-T)

c) Synthesis of silanes of the formula
R ¹

Cl-Si-Cl

(CH ₂ ),
O
POA

60

This synthesis was also carried out according to methods known in the literature.

1850 g (1 mol) of an allyl butyl polyether of the formula

to oxyethylene groups of 56.5: 43.5, which are in random distribution, are mixed with 90 mg of pyridine (ethylene) PtCl ₂ and heated to 12O ⁰ C. At this temperature, 230 g (2 mol) of methyldichlorosilane are added dropwise over the course of 2 hours. The reaction is then allowed to continue for a further 5 hours at the same temperature. The excess methyldichlorosilane is then distilled off again at a bath temperature of 120 ° C. and a pressure of 15 mm. The residue has a Cl content of 3.68%, which agrees very well with the theoretically expected Cl content of 3.61%.
Synthesis of silanes of the formula

R '

CI-Si - Cl
O
PO Λ

598.4 g (4 mol) of methyltrichlorosilane are mixed with 800 ml of toluene and 111.3 g (1.1 mol) of triethylamine mixed. 1810 g (1 mol) of a polyether of the formula are added to this mixture

/ 7-C ₄ H ₉ O- (CH ₂₁ O) ₁ H

(with a weight ratio of the oxypropylene to oxyethylene groups of 56.5: 43.5, produced by the addition of ethylene oxide and propylene oxide to n-butanol, in a statistical distribution) within 2 hours. It is stirred vigorously and the internal temperature is kept at 25 ° C. by cooling. After a reaction time of 1 hour, the mixture is filtered with exclusion of moisture, the methyltrichlorosilane and the excess triethylamine are distilled off together with the toluene up to a temperature of 70 ° C and a vacuum of 15 mm. The residue is filtered again with exclusion of moisture. It has a Cl content of 3.80%, which agrees well with the theoretically expected Cl content of 3.69%
d) Synthesis of the foam stabilizers of the general formula which can be used according to the invention

R ² O-

R ¹

Si - O -

(CH ₂ ),
O
POA

CH ₃

Si-O-

CH ₃

R ¹

Si-OR ² (CH ₂ ),
O
POA

with a weight ratio of oxypropylene batch:

π mol (X ^ ö-dihydroxypolydiniethylsiloxane (prepared according to the procedure described under b)),

n + \ mole of a silane of the formula

If, according to d) 62.2 g (0.15 mol)

R ¹

Cl-Si-Cl
(CH ₂ ) ₃

O ίο

PO Λ

(produced according to the ι -, regulation described under c),

2.2 · η + 2.2 moles of triethylamine (anhydrous), 3 moles (50% excess) of the compound R ^: OH, Tuiuui in cinci amount, and a weight ratio of toluene to total amount of other substances of 2 : 1 is present.

The silane is presented together with the toluene. A mixture of the Λ, ω-dihydroxypolydimethylsiloxane and triethylamine is then added dropwise over the course of 2 hours with stirring. The reaction mixture is kept at 20 to 25 ^° C. by cooling. After a subsequent reaction of 2 hours, R ² is OH and m added after a further 2 hours of reaction time it is filtered, toluene, R up to 7O ⁰ C and 15 mm ² OH and distilled off and the residue Triäthylaminüberschuß filtered again.
If you use the η conversion shown here instead of the silanes

HO

CH,

Si —ΟΙ CH,

with 134.6 g (0.9 mol) of methyltrichlorosilane using 33.3 g (0.33 mol) of triethylamine as Reacts acid acceptor in 460 g of toluene, then according to gas chromatographic analysis 85% the theory

Cl - Si - O

C!

r "..

Si - O -

CH ₃

Si-Cl

Cl

The product purified by means of preparative gas chromatography had an acid value of 6.21 m eq / g (theory 6.24 m eq / g). That Nuclear magnetic resonance spectrum of this substance showed a signal distribution for the protons of the various Methyl groups, which also confirmed the above formula.

R ¹

Cl-Si-Cl
(CH ₂ ),
O
POA

the silanes of the formula

R ¹
Cl-Si-Cl

I. ο

POA

is used, the synthesis of which is also shown under c), polyalkylene glycol-polysiloxane block copolymers are obtained of the general formula where M = - O -.

e) Evidence that in the synthesis shown, the segmental unit of the siloxane blocks is retained remain

Examples 1-7

To check the foam stabilizer capacity of the foam stabilizers which can be used according to the invention the following recipe is used:

g polyether triol. consisting of 93 to 4) 95 wt .-% oxypropylene units and 5 to 7

% By weight of oxyethylene units, OH number 45 to 50, obtained by the addition of ethylene oxide and propylene oxide to glycerine
0.27 g of tin octoate
V) 4.05 g H ₂ O

0.15 g Ν, Ν-dimethylethanolamine
0.05 g of N-ethylmorpholine
Xg silicone foam stabilizer
g monofluorotrichloromethane

52 g toluene diisocyanate, isomer ratio 2.4 to 2.6 = 80:20

In this recipe, the amount of silicone foam stabilizer is varied and found to be up to

bo what minimum concentration is still flawless Foams are obtained. This concentration is referred to as the limit concentration. These results are summarized in Table 3: The polyoxyalkylene block (POA) has an average molecular

weight of about 1800. a weight ratio of oxypropylene to oxyethylene groups of 56.5: 43.5, the are in statistical distribution, and he is with terminated with an n-butyl group.

Table 3

example η 2 I. 4th 2 30th 3 4th 4th 30th 5 4th ft

Limit concentration

Remarks

5 CH, C ₂ II, 5 CH ₃ C ₂ H, 5 CH ₃ C ₂ H, 6th C ₂ H, i-CIl 6th C ₂ II, 1-C ₃ H ₇ 4-7 CII, i-Cll,

4-7

CH,

iC ₁ II-

- (CH ₂ ), - O- 0.3 -O- 0.2 - (CH ₂ )., - O- 0.1 - (CH ₂ ) ₁ -O- 0.2 - (CHj) ₁ -O- 0.1 - (CH ₂ ), - 0- 0.3 - (CH ₂ ), - O- 0.3

42% m = 5; 35% m = 6; 10% w = 7;

11% m = 4; 42% m = 5; 35% m = 6; 10% m = 7;

Comparative experiments I-VI

For comparison, these examples were repeated with polyalkylene glycol-polysiloxane block copolymers, which are not composed in the scope of the invention. The results are shown in Table 4.

Table 4

Comparative η
attempt

Border remarks
concentration

I. 4th 4th CH, '-C ₃ H ₇ - (CH ₂ ), -O- 0.4 II 30th 4th CH, i - C ₁ H ₇ - (CH ₂ ), -O- 0.35 III 4th 7th CH ₃ i - C ₃ H ₇ - (CH ₂ ), -0- 0.4 IV 30th 7th CH, i - C ₃ H ₇ - (CH ₂ ), -0- 0.35 V 2 9 CH, i - C ₃ H ₇ - (CH ₂ ) -, -0- 1.2 VI 2 5 CH, C ₂ H, - (CH ₂ ), -O- 1.2

very coarse foam, very coarse foam, very coarse foam strongly coarse foam strongly coarse foam

not uniform segment m = 5, but equilibrated siloxane

Comparative experiment VII

The following comparative experiment shows that the foam stabilizers used according to the invention, in lower concentrations, lead to more satisfactory foams than those in US Pat. No. 3,507,815 called foam stabilizers.

Reworking of example 4, formulation B

the US-PS 35 07 815 with foam stabilizer E-9

and one to be used in the present invention

stabilizer

The stabilizer to be used according to the invention corresponds to the general formula with m = 6 and π = 4, where R 'is a C ₂ H ₅ radical, R ^{2 is} an iC ₃ H ₇ radical and M is the group - (CH ₂ ) JO- means The POA block consists of oxyethylene and oxypropylene units in a weight ratio of 40:60 with a total molecular weight of 2000.

The prior art stabilizer, E-9, became according to the example! 1 of US-PS 35 07 815 described method prepared

A polyether very similar to polyether P-2 was used. This was with a reaction product of sorbitol and propylene oxide

-, o a hydroxyl number of 470. An additional experiment was carried out with a polyether which by

Implementation of cane sugar and propylene oxide obtained

and had a hydroxyl number of 520.

Ais crude toluene diisocyanate became commercially available

available product used. The other components were identical.

The foaming tests were foamed in a mold exactly as described in Example 4 which was designed in the form of an L. In such a

bo form, the height of rise can be determined particularly well. The height of rise is the decisive factor for a foam formulation (hard foam).

Based on 100 parts by weight of polyether polyol, 0.075.03 and 0.6 parts by weight of stabilizer were added

b5 inserted. 0.075 parts by weight correspond to the 0.11 part by weight of formulation B, which relates to 150 g of polyether polyol. The rigid foams obtained showed approximately the same foam characteristics,

where the number of cells per cm of the foams, which with the stabilizers to be used according to the invention were made, was slightly larger. The special technical effect associated with the inventive

Table 5

level of stabilizers to be used is achieved, shows in this case, the improved flowability of the foam system and thus the height of the foam. this results from table 5.

stabilizer concentration Foam height at 760 mm Hg stabilizer g / 100 g polyol l'olyol base Polyol base Sorbitol Pipe / ucker According to the invention 0.075 98 104 According to the invention 0.3 96 108 According to the invention 0.6 101 115 E-9 of U.S. Patent 3,507,815 0.075 86 94 F-O Ηργ US-PS 35 07 8! 5 0.3 83 Q7 E-9 of U.S. Patent 3,507,815 0.6 88 103

Comparative experiment VIII

Reworking of Example 9 with

Foam stabilizer E-14 of US Pat. No. 3,507,815

and with to be used according to the invention

stabilizer

It was not possible to rework Example 9 without further ado, since the polyether P-5 used is described as a polyether which has been obtained by reacting glycerol and ethylene oxide having a hydroxyl number of 56. Such a polyether would, however, have three blocks with 22 to 23 units of oxyethylene each, corresponding to the molecular weight and uniform distribution of the ethylene oxide units on the OH groups of the glycerol. However, such a product has a melting point above 50 ^° C., ie it is waxy solid and cannot be used in this form for foaming. There is obviously an error in the description of the polyether. This is also indicated by the fact that, as a rule, no flexible foams are produced with polyethers which contain only ethylene oxide. To rework Example 9, a polyether was therefore used as described in Example 1, namely a polyether consisting of 93 to 95% by weight of oxypropylene units and 5 to 7% by weight of oxyethylene units, an OH number of 45 up to 50, obtained by the addition of ethylene oxide and propylene oxide to glycerine. As can be seen from the OH number, this polyether largely corresponds to polyether P-5, but has additional oxypropylene units which lower the melting point of the product.

The foam stabilizer E-14 was used as the foam stabilizer in accordance with the prior art used, prepared according to the figures in column 13/14 and the process information of Example 1 U.S. Patent 3,507,815.

The foam stabilizer to be used according to the invention was a stabilizer of approximately the same structure as used in comparative experiment VII, with the difference that the molecular weight of the POA block 2200 was.

The foaming was carried out according to the recipe of Example 9 of US Pat. Am The number of pores per cm was determined.

The information in Table VII, Column 18 of the U.S. Patent,

y refer to cells per inch (COl). For the Foam stabilizers E-14 are given in Example 9 at 0.6% by weight of stabilizer 57.5 CPI. That corresponds to 22.6 cells per cm; a value which is very difficult to measure considering that at

in such a value the size of each cell below 0.5 mm. Such a statement is not believed to be entirely realistic.

The CPI value for the stabilizer E-14 with an addition of 0.3% by weight is given as 5. That

r, corresponds to 2 cells per cm. So this is a structure that is only vaguely similar to a foam, since the cells are on average 5 mm in size are. Such a foam can hardly be used technically.

Table 6 shows the skinning results depending on the stabilizer used and weight amount.

Table 6

stabilizer g stabilizer number lizer of cells 100 g each per cm Polyol E-14 of U.S. Patent 3,507,815 0.3 6th E-14 of U.S. Patent 3,507,815 0.6 18th According to the invention 0.3 15th According to the invention 0.6 18th

The table shows that the stabilizer to be used according to the invention even at a low concentration of 03 g per 100 g of polyol its approximated fully effective. This is in agreement with the aforementioned comparative tests. There it is shown that the limit concentration of the stabilizers to be used according to the invention is between 0.1 and 0.3% by weight, based on polyol while the limit concentration of prior art stabilizers not according to the invention is greater is

Claims (2)

Claims; 1. Process for the production of polyurethane foams by reacting polyether alcohols and polyisocyanates with additives of water or low-boiling blowing agents, catalysts and foam stabilizers on the Base of Ρο ^ βϋίνΙβηβ ^ οΚΡο ^ Βϋοχβη-ΒΙοο ^ Copolymers, characterized in that the polyalkylene glycol-polysiloxane block copolymers are those of the general formula R ² O- R ¹ CH ₃ m I. I. si — ο- Si — Ο Ι Ι M. CH ₃ I. POA R ¹ Si-OR ² I. POA is used, in which m is uniform in segments or approximately uniform in segments = 5 or 6 or the index m is between 4 and 7, whereby the number of segments of the index 5 and 6 is at least twice as large as the number of segments of the index 4 and 7, n> 2, R ^{1 is} a saturated alkyl radical with 1 to 8 carbon atoms, R ^{2 has} the meaning of the radical R ¹ or the groups -POA or R ₃ represents », M is oxygen or an alkylenoxy radical with 1 to 3 carbon atoms -CH ₂ -CH-CH ₂ -O CH ₃ - (CHJ ₁₀ -CO Il ο or - CH ₂ - CH - C - O group R ³ O with R ³ = H or CH ₃ - in which the carbon atom is linked to the silicon atom and the terminal oxygen atom is linked to the polyoxyalkylene group, and POA is a radical terminated by an alkyl radical with 1 to 8 carbon atoms or a pheny radical with polyoxyethylene and Is polyoxypropylene units in the weight ratio of 50:50 to 30:70, which has a block molecular weight of 1,400 to 3,000. 2. The method according to claim 1, characterized in that a polyalkylene glycol-polysiloxane block copolymer is used in which the Radical R 'is a methyl radical. It is from a wide variety of patents, from only the DE-PS 12 33 133 is to be mentioned as a representative, known to use polyoxyalkylene-polysiloxane block mixed polymer as foam stabilizers the. A summarizing section on the production of such polyurethane foams and the process involved Block copolymers used as foam stabilizers can also be found in the book Saunders and Frisch »Polyurethanes, Chemistry and Technology ", Volume XVI of the SeHe" High Polymers ", Interscience Pubiishers, New York, Londen, TL1 (1962) and 1X2 (1964). The block copolymers used so far What is common is that the polysiloxane block is not uniform in segments, but rather is made up of diraethylsiloxy units of different chain lengths. That means, that in addition to low molecular weight polysiloxane radicals such average molecular weight and high molecular weight exist who are. It is used in various patents as well stated to use such polysiloxane blocks whose statistical chain length distribution sjurch a Equilibration reaction corresponds to the statistical equilibrium From US-PS 35 07 815 a method for the production of Pclyäthemrethanschaunistoffen is already through Reaction of an organic polyisocyanate with a polyether which has at least two hydroxyl groups contains, in the presence of a catalyst, one Foam stabilizer which is a hydrolysis-stable siloxane-oxyalkylene block polymer and a blowing agent such as water and fluorocarbons are known The foam stabilizer can be used in a wide range of amounts between 0.1 and 10% by weight on the entire foam base. The object of the invention is to provide a process for the production of polyether urethane foams in which smaller amounts of foam stabilizers are used than is the case according to the prior art r> Technology is common and in which foams with an improved flowability and thus an improved height of the foam. this is achieved through the use of certain polyoxyalkylene glycol-polysiloxane block mixed polymers The invention therefore relates to a method for producing polyether urethane foams by Conversion of polyether alcohols and polyisocyanates with the addition of water or low boiling points Blowing agents, catalysts and foam stabilizers 4 ^r > based on polyalkylene glycol-polysiloxane block copolymers. The process is characterized in that the polyalkylene glycol-polysiloxane block copolymers are those of the general formula