METHOD FOR PRODUCING ORGANYLOXYSILANE-TERMINATED POLYMERS

Abstract

A process for preparing silane-terminated polymers (SP) of the formula (I),

Y—[O—C(═O)—NH—(CR.sup.1.sub.2).sub.b—SiR.sub.a(OR.sup.2).sub.3-a].sub.x  (I),

includes in a 1.sup.st process step at least one polymer (OHP) of the formula (II),

Y—[OH].sub.x  (II),

being reacted with at least one isocyanate-functional silane (IS) of the formula (III),

O═C═N—(CR.sup.1.sub.2).sub.b—SiR.sub.a(OR.sup.2).sub.3-a  (III),

with the proviso that the isocyanate-functional silanes (IS) are used in an amount such that there are at least 1.05 isocyanate groups in the silanes (IS) to each hydroxyl group in the compounds (OHP). Subsequently, in a 2.sup.nd process step, the unreacted isocyanate groups of the silanes (IS) are reacted, in the reaction mixture obtained in the 1.sup.st process step, with at least one alcohol (A) of the formula (IV),

R.sup.3OH  (IV)

Subsequently, in a 3.sup.rd process step, the reaction mixture obtained in the 2.sup.nd process step is passed through an evaporation unit (VD).

Claims

1-8. (canceled)

9. A process for preparing silane-terminated polymers (SP) of the formula (I)
Y—[O—C(═O)—NH—(CR.sup.1.sub.2).sub.b—SiR.sub.a(OR.sup.2).sub.3-a].sub.x  (I), characterized in that in a 1.sup.st process step at least one polymer (OHP) of the formula (II)
Y—[OH].sub.x  (II) is reacted with at least one isocyanate-functional silane (IS) of the formula (III)
O═C═N—(CR.sup.1.sub.2).sub.b—SiR.sub.a(OR.sup.2).sub.3-a  (III) with the proviso that the isocyanate-functional silanes (IS) are used in an amount such that there are at least 1.05 isocyanate groups in the silanes (IS) to each hydroxyl group in the compounds (OHP), where Y is an x-valent polymer radical, R may be identical or different and is a monovalent, optionally substituted hydrocarbon radical, R.sup.1 may be identical or different and is hydrogen atom or a monovalent, optionally substituted hydrocarbon radical, R.sup.2 may be identical or different and is hydrogen atom or a monovalent, optionally substituted hydrocarbon radical, x is an integer from 1 to 50, a may be identical or different and is 0, 1 or 2, and b may be identical or different and is an integer from 1 to 10, subsequently in a 2.sup.nd process step the unreacted isocyanate groups of the silanes (IS) are reacted, in the reaction mixture obtained in the 1.sup.st process step, with at least one alcohol (A) of the formula (IV)
R.sup.3OH  (IV), where R.sup.3 is a hydrocarbon radical having 1 to 4 carbon atoms, and subsequently in a 3.sup.rd process step the reaction mixture obtained in the 2.sup.nd process step is passed through an evaporation unit (VD) in which the reaction mixture in a layer thickness of not more than 5 cm is exposed to a pressure of at most 80 mbar and temperatures of at most 200° C., with the carbamatosilane (CS) formed in the 2.sup.nd process step, of the formula (V)
R.sup.3O—C(═O)—NH—(CR.sup.1.sub.2).sub.b—SiR.sub.a(OR.sup.2).sub.3-a  (V), in which all the variables have the definition stated above, being at least partly evaporated and removed.

10. The process as claimed in claim 9, wherein the carbamatosilane content in the reaction mixture obtained after the process of the invention is at most 0.3 wt %, based on the total weight of the reaction mixture.

11. The process as claimed in claim 9, wherein the carbamatosilane content in the reaction mixture obtained after the process of the invention is at most 0.1 wt %, based on the total weight of the reaction mixture.

12. The process as claimed in claim 9, wherein the isocyanatosilane (IS) is used in the 1.sup.st process step in an amount such that there are at least 1.10 isocyanate groups in the compounds (IS) for each hydroxyl group of the polymer (OHP).

13. The process as claimed in claim 9, wherein the 1.sup.st and 2.sup.nd process steps are carried out in the presence of a catalyst (K).

14. The process as claimed in claim 9, wherein the 3.sup.rd process step is carried out such that the reaction mixture has a mean residence time in the evaporation unit (VD) of at most 20 minutes.

15. The process as claimed in claim 9, wherein the reaction mixture during the 3.sup.rd process step in the evaporator unit (VD) is exposed to a temperature of at most 180° C.

16. The process as claimed in claim 9, wherein all the process steps are carried out under inert gas atmosphere.

Description

EXAMPLE 1A: PREPARATION OF A POLYPROPYLENE GLYCOL HAVING TRIMETHOXYSILYLPROPYL END GROUPS AND AN AVERAGE MOLAR MASS OF 12 000 G/MOL

[0079] A 500 ml reaction vessel with stirring, cooling and heating means is charged with 400.0 g (33.33 mmol) of a hydroxy-terminated polypropylene glycol having an average molar mass M.sub.n of 12 000 g/mol (available commercially under the name Acclaim 12200 from Covestro AG, Leverkusen (DE)) and this initial charge is dried with stirring at 80° C. and 1 mbar for 2 h. Thereafter the vacuum is broken with nitrogen. The entire subsequent reaction is carried out under a nitrogen inert gas atmosphere.

[0080] To carry out the silane termination, the dried polyether is admixed at 80° C. first with 16.42 g (80.00 mmol) of isocyanatopropyltrimethoxysilane (available commercially under the name GENIOSIL® GF40 from Wacker Chemie AG, Munich (DE)) and then with 0.62 g of Borchi catalyst 315 (a catalyst containing bismuth neadecanoate, from Borchers), using an Eppendorf pipette. This corresponds to a value of 150 ppm by weight of catalyst, based on the total weight of the reaction mixture. Directly after the addition of catalyst, the reaction mixture heats up to 83-84° C. Thereafter it is stirred at a temperature of 80° C.

[0081] After 60 min, the reaction mixture is cooled to 60° C., and 0.64 g (20.00 mmol) of methanol is added. This is followed by stirring for 30 min more. Thereafter a sample of the reaction mixture is taken and is studied by IR analysis for any residues of isocyanatosilane still present. The sample is isocyanate-free.

[0082] Finally, the sample is passed at a metering rate of 160 g/h through a short-path evaporator with Teflon wipers and an internal cooling coil. The short-path evaporator has a diameter of 8 cm and a length of 26 cm. The wall temperature of the short-path evaporator is 130° C. and the applied pressure is 1 mbar. The end product is collected in the liquid-phase drain of the short-path evaporator. At 411 g, the yield is virtually quantitative.

EXAMPLE 1B: PREPARATION OF A POLYPROPYLENE GLYCOL HAVING TRIMETHOXYSILYLPROPYL END GROUPS AND AN AVERAGE MOLAR MASS OF 12 000 G/MOL

[0083] The procedure is as in example 1a, with the following amendments being made: [0084] Between 2.sup.nd process step (reaction with methanol) and 3.sup.rd process step (thin-film treatment), a sample of 50 g is taken from the reaction mixture. [0085] During the subsequent thin-film step on the remaining reaction mixture, the short-path evaporator is operated with a wall temperature of 110° C.

COMPARATIVE EXAMPLE 1C(V): PREPARATION OF A POLYPROPYLENE GLYCOL HAVING TRIMETHOXYSILYLPROPYL END GROUPS AND AN AVERAGE MOLAR MASS OF 12 000 G/MOL

[0086] This is the 50 g sample taken from the reaction mixture in example 1b before the final thin-film step.

COMPARATIVE EXAMPLE 1D(V): PREPARATION OF A POLYPROPYLENE GLYCOL HAVING TRIMETHOXYSILYLPROPYL END GROUPS AND AN AVERAGE MOLAR MASS OF 12 000 G/MOL

[0087] The procedure is as in example 1a, with the following amendments being made: [0088] Instead of the last thin-film step, a batch distillation is carried out. For this purpose, the reaction flask in which process steps 1 and 2 have been carried out is provided with a Claisen condenser. Thereafter the pressure is reduced to 1 mbar and the reaction mixture is heated to 130° C. The vacuum distillation is carried out for a period of 1 h with intense stirring of the reaction mixture, after which a sample is taken. [0089] Thereafter the vacuum distillation is continued for a further hour, and again a sample is taken.

COMPARATIVE EXAMPLE 1E(V): PREPARATION OF A POLYPROPYLENE GLYCOL HAVING TRIMETHOXYSILYLPROPYL END GROUPS AND AN AVERAGE MOLAR MASS OF 12 000 G/MOL

[0090] The procedure is as in example 1d(V), with the following amendments being made: [0091] The vacuum distillation is carried out at a temperature of 160° C. instead of 130° C.

EXAMPLE 2: DETERMINATION OF PROPERTIES OF THE POLYMER MIXTURES OBTAINED

[0092] Viscosities are determined by the method described in the description.

[0093] Hazen color numbers are determined in accordance with ISO 6271, Part 2.

[0094] The carbamatosilane (N-(3-trimethoxysilylpropyl)-O-methylcarbamate) content is determined via a GC headspace method. This method is complicated by two problems: [0095] 1. Because the carbamatosilane content is very small and is heavily dependent on the composition of the matrix, it is uncertain whether a uniform calibration plot can be used for all samples. [0096] 2. For the production of a calibration plot there is “blank sample” (i.e., a sample entirely without carbamatosilane), since small amounts of carbamatosilane are formed as a secondary product, even without addition of methanol, during the first synthesis step itself (i.e., during the reaction of polymer with isocyanatosilane).

[0097] In a method which has proven appropriate, therefore, three 50 g samples are taken from each polymer mixture to be analyzed; of these three samples, one remains unchanged, one is admixed with 0.30 wt % of carbamatosilane, and one with 0.60 wt % of carbamatosilane. When these three samples are subsequently measured by headspace GC, integration of the respective carbamatosilane peaks yields three equations with two unknowns (A1=x*c; A2=x*(c+0.3); A3=x*(c+0.6), wherein A1, A2 and A3 are the integrated peak areas, x is the proportionality factor, and c is the target concentration of carbamatosilane). The carbamatosilane peak here is easy to perceive, since it is the only peak significantly differentiating the GC spectra of the three samples.

[0098] Since even two equations with two unknowns can be solved mathematically, it is possible here, as a result of the different combination possibilities, to compute three solutions for the concentration c. These three solutions must of course lead to the same result within the bounds of measurement accuracy, i.e., with an error tolerance for the carbamatosilane content that is ±10% of the respective measurement value. If this should not be the case, the measurement must be repeated.

[0099] NB: Because the precise metering, described above, of such small amounts of carbamatosilane is not easy in practice, it is also possible to operate with a slightly different metered amount. This difference must merely be noted, and the exact value metered must be entered into the corresponding equation. If, in other words, for example, instead of the intended 0.30 wt %, 0.32 wt % was accidentally metered, the measurement can be continued nevertheless. In the final calculation, however, the corresponding equation must then read A2=x*(c+0.32).

[0100] In order to implement the headspace measurement, a 0.5 g sample is weighed out into a 20 ml headspace vial, with the vial being blown out cautiously with nitrogen for around 30 s before being closed. The vial is subsequently heated at 150° C. for 30 min, after which the gas mixture above the sample is passed directly into the GC via a hot transfer capillary at 170° C. Duplicate determinations are carried out in each case for all of the samples.

[0101] With the polymer mixtures prepared in examples 1a to 1e, the following results are obtained, set out in table 1.

TABLE-US-00001 TABLE 1 1d(V) 1d(V) 1e(V) 1e(V) Example 1a 1b 1c(V) 1 h* 2 h* 1 h* 2 h* Temperature 130 110 — 130 130 160 160 in step 3 [° C.] Viscosity [Pas] 7.3 7.2 7.1 7.2 7.1 7.3 7.5 Color number 18 17 17 31 42 88 102 Hazen Carbamatosilane 0.011 0.024 0.70 0.68 0.64 0.50 0.41 contents [wt %] *The examples labelled “1 h” describe the sample after a distillation time of 1 h, and the examples labelled “2 h” describe the sample after a distillation time of 2 h.

EXAMPLE 3: PREPARATION OF A POLYPROPYLENE GLYCOL HAVING TRIMETHOXYSILYLPROPYL END GROUPS AND AN AVERAGE MOLAR MASS OF 18 000 G/MOL

[0102] The procedure is as in example 1 b, with the following amendments being made: [0103] Instead of 400.0 g of a hydroxy-terminated polypropylene glycol having an average molar mass M.sub.n of 12 000 g/Mol, 400.0 g (22.22 mmol) of a hydroxy-terminated polypropylene glycol having an average molar mass M.sub.n of 18 000 g/mol (available commercially under the name of Acclaim 18200 from Covestro AG, Leverkusen (DE)) are used. [0104] Instead of 16.42 g (80.00 mmol) of isocyanatopropyltrimethoxysilane, 10.95 g (53.33 mmol) of the same isocyanatosilane are added dropwise. [0105] Instead of 0.64 g (20.00 mmol) of methanol, only 0.43 g (13.33 mmol) of methanol is used. [0106] After the end of the 2.sup.nd process step (i.e., reaction with methanol), a 50 gram sample (“sample 1”) is taken. [0107] The remaining amount of product is subjected, as described in example 1 b, to the 3.sup.rd process step (thin-film treatment at 110° C.). The product obtained in that step is referred to as “sample 2”.

[0108] All other parameters remain unchanged.

EXAMPLE 4: DETERMINATION OF PROPERTIES OF THE POLYMER MIXTURES OBTAINED

[0109] Viscosities, Hazen color numbers, and carbamatosilane (N-(3-trimethoxysilylpropyl)-O-methylcarbamate) contents are also determined as described in example 2.

[0110] With the samples generated in example 3, the following results are obtained, set out in table 2.

TABLE-US-00002 TABLE 2 Sample 1 Example 3 (comparative) Sample 2 Temperature in step 3 [° C.] — 110 Viscosity [Pas] 26.3 26.5 Color number, Hazen 13 13 Carbamatosilane content [wt %] 0.49 0.039

EXAMPLE 5: PREPARATION OF A POLYPROPYLENE GLYCOL HAVING ALPHA-METHYLDIMETHOXYSILYLMETHYL END GROUPS AND AN AVERAGE MOLAR MASS OF 12 000 G/MOL

[0111] The procedure is as in example 1a, with the following amendments being made: [0112] Instead of 16.42 g (80.00 mmol) of isocyanatopropyltrimethoxysilane, 12.90 g (80.00 mmol) of alpha-isocyanatomethylmethyldimethoxysilane (available commercially under the name GENIOSIL® XL 42 from Wacker Chemie AG, Munich (DE)) are used. [0113] After the end of the 2.sup.nd process step (i.e., reaction with methanol), a 50 gram sample (“sample 1”) is taken. [0114] The remaining amount of product is subjected, as described in example 1a, to the 3.sup.rd process step (thin-film treatment), with the short-path evaporator operated with a wall temperature of 90° C. The product obtained in that step is referred to as “sample 2”.

[0115] All other parameters remain unchanged.

EXAMPLE 6: DETERMINATION OF PROPERTIES OF THE POLYMER MIXTURES OBTAINED

[0116] Viscosities and Hazen color numbers of the samples from example 5 are also determined as described in example 2. The alpha-N-(methyldimethoxysilylmethyl)-O-methylcarbamate content is determined in an equivalent way to the determination for carbamatosilanes that is described in example 2. The only difference lies in the fact that, of course, the headspace GC peak analyzed is that for the carbamatosilane to be determined here.

[0117] With the samples generated in example 5, the following results are obtained, set out in table 3.

TABLE-US-00003 TABLE 3 Sample 1 Example 5 (comparative) Sample 2 Temperature in step 3 [° C.] — 90 Viscosity [Pas] 7.1 7.1 Color number, Hazen 8 8 Carbamatosilane content [wt %] 0.59 0.057

EXAMPLE 7: PREPARATION OF A POLYPROPYLENE GLYCOL HAVING ALPHA-METHYLDIMETHOXYSILYLMETHYL END GROUPS AND AN AVERAGE MOLAR MASS OF 18 000 G/MOL

[0118] The procedure is as in example 5, with the following amendments being made: [0119] Instead of 400.0 g of a hydroxy-terminated polypropylene glycol having an average molar mass M.sub.n of 12 000 g/Mol, 400.0 g (22.22 mmol) of a hydroxy-terminated polypropylene glycol having an average molar mass M.sub.n of 18 000 g/mol (available commercially under the name of Acclaim 18200 from Covestro AG, Leverkusen (DE)) are used. [0120] Instead of 12.90 g (80.00 mmol) of alpha-isocyanatomethylmethyldimethoxysilane, 8.60 g (53.33 mmol) of the same isocyanatosilane are added dropwise. [0121] Instead of 0.64 g (20.00 mmol) of methanol, only 0.43 g (13.33 mmol) of methanol is used. [0122] As in example 5, here as well, after the end of the 2.sup.nd process step (i.e., reaction with methanol), a 50 gram sample (“sample 1”) is taken. [0123] The remaining amount of product is subjected, as described in example 1b, to the 3.sup.rd process step (thin-film treatment at 110° C.). The product obtained in that step is referred to as “sample 2”.

[0124] All other parameters remain unchanged.

EXAMPLE 8: DETERMINATION OF PROPERTIES OF THE POLYMER MIXTURES OBTAINED

[0125] Viscosities, Hazen color numbers, and carbamatosilane (alpha-N-(methyldimethoxysilylmethyl)-O-methylcarbamate) contents are also determined as described in example 2.

[0126] With the samples generated in example 7, the following results are obtained, set out in table 4.

TABLE-US-00004 TABLE 4 Sample 1 Example 7 (comparative) Sample 2 Temperature in step 3 [° C.] — 110 Viscosity [Pas] 26.2 26.2 Color number, Hazen 9 9 Carbamatosilane content [wt %] 0.40 0.050