Process for preparing (meth)acrylamido-functional silanes by the reaction of aminoalkyl alkoxysilanes with acrylic acid anhydride

1. A process for preparing an acrylamidoalkyl-functional silane, the process comprising:

reacting an aminoalkyl-functional alkoxysilane of formula I or a mixture comprising at least two silanes of the formula I with an acrylic anhydride of formula IV to obtain an intermediate reaction product:

(R 1 O) 3−a−b (R 2 ) a Si(B) 1+b   (I)

(CHR 5 ═CR 4 CO) 2 O  (IV); and

optionally partially removing an acrylic acid and/or reaction products of the acrylic acid from the intermediate reaction product, to form the acrylamidoalkyl-functional silane,

wherein:

R 4 is independently a hydrogen atom or a methyl group and R 5 is independently a hydrogen atom or a methyl group;

R 1 is independently a linear, branched or cyclic alkyl group having 1 to 8 carbon atoms;

R 2 is independently a linear, branched or cyclic alkyl group having 1 to 8 carbon atoms;

a is independently 0 or 1;

b is independently 0, 1 or 2; and

group B is independently a group of formula II or a group of formula III

—(CH 2 ) c —[(NH)(CH 2 ) d ] e [(NH)](CH 2 ) f ] g NH (2−h) R 3 h   (II)

—(CH 2 ) j —NH 2−p (CH 2 —CH 2 —NH 2 ) p   (III),

wherein:

R 3 is independently a linear, branched or cyclic alkyl, aryl or alkylaryl group having 1 to 8 carbon atoms;

c is independently selected from 1, 2, 3, 4, 5 and 6;

d is independently selected from 1, 2, 3, 4, 5 and 6;

e is independently selected from 0, 1, 2, 3, 4, 5 and 6;

f is independently selected from 1, 2, 3, 4, 5 and 6;

g is independently selected from 0, 1, 2, 3, 4, 5 and 6;

h is independently 0 or 1;

j=1, 2 or 3 and

p=0, 1 or 2.

2. The process according to claim 1 , wherein the reacting occurs at a temperature below 80° C.

3. The process according to claim 1 , wherein the reacting occurs essentially in the absence of a solvent or diluent, such that the solvent or diluent content in the overall composition is less than or equal to 0.5% by weight.

4. The process according to claim 1 , wherein the reacting occurs within a temperature range below 50° C., and in the absence of a stabilizer.

5. The process according to claim 1 , wherein the reacting occurs in the presence of an anhydrous aprotic or organic protic solvent at a temperature below 40° C.

6. The process according to claim 1 , wherein in the aminoalkyl-functional alkoxysilane of formula I:

a) R 1 is independently methyl or ethyl where a=0, b=0, c=1, 2 or 3 and group B is of formula II where g=0, e=1 h=0, and d=1, 2, 3;

b) R 1 is independently methyl or ethyl where a=0, b=0, c=3 and group B is of formula II where g, e and h each 0 or, in an alternative, a=0, b=0, c=3, and group B is of formula II where e=1, d=1, 2, 3, g=0, h=0 or group B is of formula II where e=g=0 or 1, and d=f=2 or 3 and h=0 with c=3 or group B is of formula III where j=3 and p=1 or 2;

c) R 1 is independently methyl or ethyl where a=0, b=0, c=2 and group B is of formula II where g, e and h each 0 or, in an alternative, where a=0, b=0, c=3, and group B is of formula II where e=1, d=1, 2, 3, and g=0, h=0 or group B is of formula II where e=g=0 or 1, and d=f=2 or 3 and h=0 with c=2 or group B is of formula III where j=3 and p=1 or 2; or

d) R 1 is independently methyl or ethyl where a=0 and b=0 with c=1 and group B is of formula II where g, e and h each 0 or, in an alternative, where a=0, b=0, c=3, and group B is of formula II where e=1, d=1, 2, 3, and with g=0, h=0 or group B is of formula II with e=g=0 or 1, and d=f=2 or 3 and h=0 with c=1 or group B is of formula III where j=3 and p=1 or 2.

7. The process according to claim 1 , wherein the aminoalkyl-functional silane of the formula I is selected from the group consisting of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 1-aminomethyltrimethoxysilane, 1-aminomethyltriethoxysilane, 2-aminoethyltrimethoxysilane, 2-aminoethyltriethoxysilane, 3-aminoisobutyltrimethoxysilane, 3-aminoisobutyltriethoxysilane, N-n-butyl-3-aminopropyltriethoxysilane, N-n-butyl-3-aminopropylmethyldiethoxysilane, N-n-butyl-3-aminopropyltrimethoxysilane, N-n-butyl-3-aminopropylmethyldimethoxysilane, N-n-butyl-1-aminomethyltriethoxysilane, N-n-butyl-1-aminomethylmethyldimethoxysilane, N-n-butyl-1-aminomethyltrimethoxysilane, N-n-butyl-1-aminomethylmethyltriethoxysilane, benzyl-3-aminopropyltrimethoxysilane, benzyl-3-aminopropyltriethoxysilane, benzyl-2-aminoethyl-3-aminopropyltrimethoxysilane, benzyl-2-aminoethyl-3-aminopropyltriethoxysilane, diaminoethylene-3-propyltrimethoxysilane, diaminoethylene-3-propyltriethoxysilane, triaminodiethylene-3-propyltrimethoxysilane, triaminodiethylene-3-propyltriethoxysilane, (2-aminoethylamino)ethyltrimethoxysilane, (2-aminoethylamino)ethyltriethoxysilane, (1-aminoethylamino)methyltrimethoxysilane and (1-aminoethylamino)methyltriethoxysilane.

8. The process according to claim 1 , wherein the acrylic anhydride of formula IV is methacrylic anhydride or (unsubstituted) acrylic anhydride.

9. The process according to claim 1 , wherein a molar ratio of nitrogen atoms in the aminoalkyl-functional alkoxysilanes of formula I to a molar ratio of the acryloylcarbonyl function released from the acrylic anhydride of formula IV is from 1:5 to 5:1.

10. The process according to claim 1 , wherein the acrylic acid is not removed in the case of reaction of aminoalkyl-functional silanes of formula I with secondary and/or tertiary nitrogen atoms.

11. The process according to claim 1 , comprising:

converting the aminoalkyl-functional alkoxysilane of formula I with addition of a defined amount of acrylic anhydride of formula IV and under temperature control; and then

removing acrylic acid.

12. The process according to claim 1 , wherein the acrylic acid is partially removed by distillation, formation of an insoluble compound or by chromatography, or is masked by addition of a complexing agent.

13. The process according to claim 1 , wherein the reacting occurs in the presence of an anhydrous aprotic or organic protic solvent or solvent mixture, with a solvent forming insoluble compounds with the acrylic acid.

14. The process according to claim 1 , wherein the acrylamidoalkyl-functional silane is of formula V:

(R 1 O) 3−a−b (R 2 ) a Si(C) 1+b   (V),

wherein:

R 1 is independently a linear, branched or cyclic alkyl group having 1 to 8 carbon atoms, or an acryloylcarbonyl of formula:

—(CO)R 4 C═CR 5 H;

R 2 is independently a linear, branched or cyclic alkyl group having 1 to 8 carbon atoms;

the C group is an acrylamidoalkyl-functional group;

a is independently 0 or 1; and

b is independently 0, 1 or 2.

15. The process according to claim 14 , wherein the C group is selected from the group consisting of

—(CH 2 ) c —[(NH)(CH 2 ) d ] e [(NH)](CH 2 ) f ] g NH (1−h) R 3 h —(CO)CR 4 ═CHR 5 ,

—(CH 2 ) j —NH(CH 2 —CH 2 —NH)—(CO)CR 4 ═CHR 5 , and

—(CH 2 ) j —NH 2−p (CH 2 —CH 2 —NH—(CO)CR 4 ═CHR 5 ) p .

16. A formulation comprising:

an acrylamidoalkyl-functional silane obtained by the process of claim 1 ;

at least one further formulation constituent selected from the group consisting of an auxiliary, a polymer, a diluent, an additive, a pigment, a filler, an acid, a base and a buffer; and

an acrylic acid.

17. The process according to claim 1 , wherein the group B is of formula II.

18. The process according to claim 1 , wherein the group B is of formula III.

19. The process according to claim 1 , comprising removing acrylic acid and/or reaction products of acrylic acid from the intermediate reaction product.