NCO-modified polyoxymethylene block copolymers

Abstract

The invention relates to a method for producing NCO-modified polyoxymethylene block copolymers comprising the step of polymerizing formaldehyde in a reaction vessel in the presence of a catalyst, the polymerization of formaldehyde in addition taking place in the presence of a starter compound comprising at least 2 Zerewitinoff active H atoms to obtain an intermediate product. The intermediate product obtained is reacted further with an isocyanate to obtain an NCO-modified polyoxymethylene block copolymer. The invention also relates to NCO-modified polyoxymethylene block copolymers obtained by a method of this type and to the use of said copolymers for producing polyurethane polymers.

Claims

1. A process for preparing NCO-modified polyoxymethylene block copolymers, comprising the step of polymerizing gaseous formaldehyde in the presence of a catalyst selected from the group consisting of basic catalysts, Lewis-acidic catalysts, and combinations thereof, to form a polyoxymethylene block copolymer intermediate, wherein the polymerization of formaldehyde is effected in the presence of a starter compound having at least two Zerewitinoff-active hydrogen atoms, giving an intermediate having a number-average molecular weight of <4500 g/mol, and reacting the intermediate with an isocyanate in the presence of a catalyst which is the same catalyst as in the preceding polymerization of formaldehyde, to give an NCO-modified polyoxymethylene block copolymer.

2. The process as claimed in claim 1, wherein the starter compound has a number-average molecular weight of 100 g/mol to 3000 g/mol.

3. The process as claimed in claim 1, wherein the starter compound is an oligomeric compound.

4. The process as claimed in claim 1, wherein the starter compound is selected from the group consisting of polyether polyols, polyester polyols, polyether ester polyols, polycarbonate polyols, polyacrylate polyols, and combinations thereof.

5. The process as claimed in claim 1, wherein the isocyanate is an aliphatic or aromatic di- or polyisocyanate.

6. The process as claimed in claim 1, wherein the polymerization is additionally effected in the presence of a comonomer.

Description

EXAMPLES

(1) The invention is illustrated in more detail by the figures and examples which follow, but without being restricted thereto. The figures show:

(2) FIG. 1 a reactor arrangement for performance of the process of the invention

(3) H-functional oligomeric compounds used:

(4) PET-1 difunctional poly(oxypropylene)polyol having an OH number of 109.6 mg.sub.KOH/g, giving the mean molecular weight M.W.=1022 g/mol and the average empirical formula HO(CH(CH.sub.3)CH.sub.2).sub.17.02H. By GPC against polypropylene glycol standards, a number-average molecular weight M.sub.n=1011 g/mol and a polydispersity index PDI=1.07 were measured.

(5) PET-2 trifunctional poly(oxypropylene)polyol (CAS No. [25791-96-2]) having an OH number of 225.5 mg.sub.KOH/g, giving the mean molecular weight M.W.=745 g/mol and the average empirical formula (C.sub.3H.sub.5O.sub.3)((CH(CH.sub.3)CH.sub.2O).sub.11.26H.sub.3. By GPC against polypropylene glycol standards, a number-average molecular weight M.sub.n=639 g/mol and a polydispersity index PDI=1.06 were measured.

(6) The formaldehyde source used was paraformaldehyde (CAS [30525-89-4]) from Aldrich (catalog number 16005, Lot#SZBB0250V).

(7) Description of the methods:

(8) The molar mass distributions were determined by means of gel permeation chromatography (GPC).

(9) Gel permeation chromatography (GPC): The measurements were effected on the Agilent 1200 Series instrument (G1310A Iso Pump, G1329A ALS, G1316A TCC, G1362A RID, G1365D MWD), detection via RID; eluent: chloroform (GPC grade), flow rate 1.0 ml/min; column combination: PSS SDV precolumn 850 mm (5 m), 2PSS SDV linear S 8300 mL (5 m). Polypropylene glycol samples of known molar mass from PSS Polymer Standards Service were used for calibration. The measurement recording and evaluation software used was the software package PSS WinGPC Unity. The GPC chromatograms were recorded in accordance with DIN 55672-1, except using chloroform as eluent rather than THF.

(10) .sup.1H NMR spectroscopy: The measurements were effected on the Bruker AV400 instrument (400 MHz); the chemical shifts were calibrated relative to the solvent signal (CDCl.sub.3, =7.26 ppm); s=singlet, m=multiplet, bs=broadened singlet, kb=complex region. The reaction of the terminal hydroxyl groups with 4-tolyl isocyanate was determined via the comparison of the integrals for the methyl groups for Tol-CH.sub.3 (2.09-2.25 ppm) and PET-1-CH.sub.3 or PET-2-CH.sub.3 (1.13-1.26 ppm).

(11) .sup.13C NMR spectroscopy: The measurements were effected on the Bruker AV400 instrument (100 MHz); the chemical shifts were calibrated relative to the solvent signal (CDCl.sub.3, =77.16 ppm); APT (attached proton test): CH.sub.2, C.sub.quart: positive signal (+); CH, CH.sub.3: negative signal (); HMBC: Hetero multiple bond correlation; HSQC: Heteronuclear single-quantum correlation.

(12) Infrared (IR) spectroscopy: The measurements were effected on the Bruker Alpha-P FT-IR spectrometer, the measurements were effected neat; signal intensities: vs=very strong (90-100/absorbance), s=strong (70-90% absorbance), m=medium (30-70% absorbance), w=weak (10-30% absorbance), vw=very weak (0-10% absorbance, in each case relative to the most intense signal); b=broadened band.

(13) Electrospray mass spectrometry (ESI-MS): The measurements were effected on the Thermo Fisher Scientific LTQ Orbitrap XL instrument; samples were diluted with MeOH.

(14) The OH number (hydroxyl number) was determined on the basis of DIN 53240-2, except using N-methylpyrrolidone rather than THF/dichloromethane as the solvent. A 0.5 molar ethanolic KOH solution was used for titration (endpoint recognition by means of potentiometry). The test substance used was castor oil with certified OH number. The reporting of the unit in mg.sub.KOH/g relates to mg[KOH]/g[polyol]. The OH number is related to the equivalent molar mass according to the following equation:
OH number [mg.sub.KOH/g]=56100 [mg.sub.KOH/mol]/equivalent molar mass [g/mol]

(15) The equivalent molar mass is understood to mean the number-average total molar mass of the material containing active hydrogen atoms divided by the number of active hydrogen atoms (functionality).

(16) The viscosity was determined on an Anton Paar Physica MCR 501 rheometer. A cone-plate configuration having a separation of 50 m was selected (DCP25 measurement system). 0.1 g of the substance was applied to the rheometer plate and subjected to a shear of 0.01 to 1000 l/s at 25 C., and the viscosity was measured every 10 s for 10 min. The viscosity averaged over all the measurement points is reported.

(17) For the reactions, an experimental apparatus consisting of two 200 mL stainless steel autoclaves which were connected via a heatable inch glass capillary (bridge) which could be shut off with a valve was used. Both reactors were equipped with a hollow shaft stirrer and manometer and were heatable independently of one another. The gas supply to reactor 1 (depolymerization reactor R1) was via an immersed tube connected to a mass flow regulator (MFC 1, capacity: 100 mL/min). The gas stream was passed through the bridge from reactor 1 into reactor 2. In reactor 2 (polymerization reactor R2) there was a gas outlet, and the offgas flow was controlled with the aid of a second mass flow regulator (MFC 2, capacity: 100 mL/min). Via MFC 1, a carrier gas stream (argon or carbon dioxide) was passed through reactor 1 with the volume flow rate {circumflex over (V)}.sub.in, and the depolymerization of paraformaldehyde to gaseous formaldehyde was conducted therein. The carrier gas stream enriched with formaldehyde gas was then passed through the heated bridge into reactor 2, in which the polymerization was conducted. By closed-loop control of MFC 2 to give a volume flow rate {circumflex over (V)}.sub.out={circumflex over (V)}.sub.in, constant pressure in the overall system was assured.

(18) The pressure reactors used in the examples had a height (internal) of 6.84 cm and an internal diameter of 5.98 cm. The reactors were equipped with an electrical heating jacket (maximum heating power 240 watts). In addition, the reactors were equipped with an inlet tube, and each was equipped with a thermal sensor of diameter 1.6 mm which projected into the reactor up to 3 mm above the base.

(19) The hollow shaft stirrer used in the examples was a hollow shaft stirrer in which the gas was introduced into the reaction mixture via a hollow shaft in the stirrer. The stirrer body mounted on the hollow shaft had four arms and had a diameter of 25 mm and a height of 7 mm. At each end of the arm was mounted a gas outlet which had a diameter of 3 mm. The rotation of the stirrer gave rise to a reduced pressure such that the gas present above the reaction mixture (CO.sub.2 and possibly formaldehyde) was sucked in and introduced through the hollow shaft of the stirrer into the reaction mixture.

Example 1

Preparation of a Bifunctional Polypropylene Oxide-Polyoxymethylene Block Copolymer and In Situ Modification with 4-Tolyl Isocyanate

(20) Reactor 1 was initially charged with a suspension of 30.34 g (1.01 mol) of paraformaldehyde, 0.67 g (2.05 mmol) of 4-dodecylbenzenesulfonic acid and 8.15 g of anhydrous 3 molecular sieve in 30 ml of undecane. Reactor 2 contained a solution of 70.0 mg (0.111 mmol) of dibutyltin dilaurate (DBTL) in 20.02 g (20.02 mmol) of PET-1. Via a bypass line connected to MFC 1, the whole system with the bridge open was pressurized to 20 bar with CO.sub.2. Then the bridge was closed and the pressure in reactor 1 was reduced to 5 bar by means of a gas outlet valve. The reaction mixture in reactor 1 was heated to 125 C. while stirring with the bridge shut off, and the reaction mixture in reactor 2 to 60 C. while stirring. The bridge temperature was adjusted to 170 C. On attainment of the reaction temperature, the pressure in reactor 2 was adjusted to a value between 17 and 19 bar. The pressure in reactor 1 was adjusted to 20 bar with CO.sub.2 via the bypass. The bypass line was closed and a constant argon flow rate {circumflex over (V)}.sub.out={circumflex over (V)}.sub.in=47.6 ml/min was established using the mass flow regulators. Directly thereafter, the bridge was opened. After 4.7 h, the bridge was closed, the system was cooled to room temperature and the pressure was released separately in reactor 1 and reactor 2. Subsequently, 5.05 mL (5.33 g, 40.0 mmol) of 4-tolyl isocyanate were introduced into reactor 2 at a flow rate of 1 mL/min while stirring at an internal temperature of 40 C. After the addition had ended, the reaction mixture in reactor 2 was stirred at 60 C. for a further 16 h. Weighing of reactor 2 before the removal of the product showed an increase in weight of 2.40 g (difference in mass minus the mass of the isocyanate fed in) for the reaction, which corresponds to a transfer of 2.40 g (79.9 mmol) of gaseous formaldehyde. 25.11 g of a viscous, colorless oil were removed from reactor 2.

(21) Viscosity: 1.744 Pa.Math.s

(22) As a result of the transfer of 2.40 g (79.9 mmol) of formaldehyde, the PET-1 used as oligomer was extended by an average of 3.95 formaldehyde units per molecule, or 1.98 formaldehyde units per chain end.

(23) By means of gel permeation chromatography (GPC) against polypropylene glycol standards, a number-average molecular weight M.sub.n=1172 g/mol and a polydispersity index PDI=1.05 were determined.

(24) .sup.1H NMR spectroscopy (400 MHz, CDCl.sub.3): =0.74-0.84 (m, 0.54; H), 0.88 (bs, 0.16; H), 0.91-1.13 (m, 25.64; H, PET-1-CH.sub.3), 1.13-1.26 (m, 2.71; H, PET-1-CH.sub.3), 2.09-2.25 (m, 3.00; H, Tol-CH.sub.3), 3.14-3.90 (m, 26.69; H, PET-1-CH/PET-1-CH.sub.2), 4.61-5.04 (kb, 1.73; H, OCH.sub.2O O/PET-1-CH(CH.sub.3)OCH.sub.2O/PET-1-CH.sub.2OCH.sub.2O), 5.23-5.38 (m, 0.98H, OCH.sub.2O), 6.92-7.02 (m, 1.79H, Tol-CH.sub.ar), 7.14-7.32 (m, 1.75H, Tol-CH.sub.ar) ppm.

(25) .sup.13C APT NMR spectroscopy (100 MHz, CDCl.sub.3): =14.0 (), 16.8 (), 17.0 (), 17.2 (), 17.3 (), 17.5 (), 17.6 (), 17.9 (), 18.1 (), 18.4 (), 20.4 (, Tol-CH.sub.3), 20.6 (, Tol-CH.sub.3), 22.5 (+), 29.2 (+), 29.5 (+), 29.5 (+), 31.8 (+), 65.4 (), 67.0 (), 67.1 (), 69.3 (+), 69.7 (+), 71.6 (+), 72.7 (+), 73.2 (+), 73.7 (+), 74.3 (+), 74.4 (+), 74.5 (), 74.8 (), 74.9 (), 75.0 (), 75.2 (), 75.3 (), 75.4 (+), 75.7 (+), 75.8 (+), 75.8 (+), 76.5 (), 82.6 (+, OCH.sub.2O), 82.7 (+, OCH.sub.2O), 85.2 (+, OCH.sub.2O), 85.8 (+, OCH.sub.2O), 88.3 (+, OCH.sub.2O), 88.5 (+, OCH.sub.2O), 88.9 (+, OCH.sub.2O), 89.8 (+, OCH.sub.2O), 90.2 (+, OCH.sub.2O), 90.4 (+, OCH.sub.2O), 90.7 (+, OCH.sub.2O), 92.0 (+, OCH.sub.2O), 92.1 (+, OCH.sub.2O). 93.8 (+, OCH.sub.2O), 94.9 (+, OCH.sub.2O), 117.8 (, Tol-CH.sub.ar), 118.8 (, Tol-CH.sub.ar), 120.8 (, Tol-CH.sub.ar), 129.2 (, Tol-CH.sub.ar), 129.4 (, Tol-CH.sub.ar), 129.5 (, Tol-CH.sub.ar), 130.1 (+), 130.7 (+), 131.5 (+), 132.3 (+), 135.2 (+, Tol-CNH), 135.4 (+, Tol-CNH), 135.6 (+, Tol-CNH), 136.7 (+, Tol-CCH.sub.3), 145.8 (+, Tol-NHC(O)O), 146.2 (+, Tol-NHC(O)O), 152.5-153.4 (+, Tol-NHC(O)O) ppm.

(26) The occurrence of a multitude of signals in the .sup.1H NMR spectrum in the range of 4.6 to 5.4 ppm, and a multitude of signals having positive polarity in the .sup.13C APT NMR spectrum in the range of 82.6 to 94.9 ppm, shows the presence of chemically nonequivalent oxymethylene groups in (CH.sub.2O).sub.n blocks having different chain lengths.

(27) In addition, the presence of the corresponding signals attributed to the carbamate in the .sup.1H and .sup.13C APT NMR spectrum shows that the reaction of the polyoxymethylene block copolymers with 4-tolyl isocyanate was successful. The comparison of the integrals for the methyl groups Tol-CH.sub.3 and PET-1-CH.sub.3 gives a ratio of 0.106 Tol-CH.sub.3 to 1 PET-1-CH.sub.3. For an average chain length of 17.02 (CH(CH.sub.3)CH.sub.2O) units per molecule, this gives an average of 1.804 4-tolyl carbamate units per molecule. The reaction of the polyoxymethylene block copolymer with 4-tolyl isocyanate accordingly proceeded with a conversion of 90%.

(28) The HMBC NMR spectrum showed long-range coupling of a PET-1 .sup.13C signal at 72.7 ppm to .sup.1H signals at 4.83 and 4.88 ppm, which, according to HSQC NMR spectroscopy, exhibited direct coupling to .sup.13C signals at about 88.9 and 90.4 ppm respectively. Both signals in the .sup.13C APT NMR have positive polarity and can be attributed to oxymethylene groups. This showed that the polypropylene oxide block is bonded covalently to the polyoxymethylene block.

(29) Additionally observed in the HMBC NMR spectrum was long-range coupling of the carbamate .sup.13C signal at about 153 ppm to .sup.1H signals at about 5.34 ppm; according to HSQC NMR spectroscopy, the latter structural unit is coupled directly to .sup.13C signals at 85.8 and 88.9 ppm. Both signals in the .sup.13C APT NMR have positive polarity and can be attributed to oxymethylene groups. Analogously, for the carbamate .sup.13C signal at 146.2 ppm, long-range coupling to CH.sub.2 groups at 5.05 (.sup.1H) and 82.7 (.sup.13C) ppm, and also 4.83 (.sup.1H) and 88.9 (.sup.13C) ppm, was observed. This showed that the tolyl carbamate groups are bonded covalently to oxymethylene groups.

(30) These long-range couplings of PET-1 end groups on the one hand and chemically nonequivalent carbamate groups on the other hand to chemically nonequivalent oxymethylene units demonstrate clearly that polyoxymethylene blocks (CH.sub.2O).sup.n having different chain length n are present, which are bonded covalently both to PET-1 and to carbamate units which originate from the reaction with 4-tolyl isocyanate. The structure of the polyoxymethylene block copolymers of the invention has thus been demonstrated beyond doubt.

(31) ESI-MS (FTMS-p): In the ESI mass spectrum, the following signal series were identified, which can be attributed to the following empirical formulae:
[H.sub.3CC.sub.6H.sub.4NHC(O)O(CH.sub.2O).sub.x(C.sub.3H.sub.6O).sub.m(CH.sub.2O).sub.yC(O)NHC.sub.6H.sub.4CH.sub.3H].sup.+

(32) Series 1 (x+y=1): m/z (%) [chain length m]=835.51583 (1.33) [9], 893.55778 (1.92) [10], 951.59968 (2.60) [11], 1009.64154 (3.03) [12], 1067.68336 (2.87) [13], 1125.72543 (2.39) [14], 1183.76712 (1.65) [15], 1241.80915 (1.05) [16].

(33) Series 2 (x+y=2): m/z (%) [chain length m]=749.47901 (3.84) [7], 807.52059 (6.67) [8], 865.56235 (8.82) [9], 923.60424 (10.15) [10], 981.64607 (10.06) [11], 1039.68768 (8.74) [12], 1097.72982 (6.52) [13], 1155.77181 (4.29) [14], 1213.81365 (2.66) [15], 1271.85565 (1.51) [16].

(34) The ESI mass spectrum shows clearly that inventive block copolymers of polypropylene oxide units (C.sub.3H.sub.6O).sub.m and polyoxymethylene units (CH.sub.2O).sub.x or (CH.sub.2O).sub.y with x+y1 have been obtained.

(35) In addition, the ESI mass spectrum shows that chains having two 4-tolyl carbamate units have been obtained, and hence the reaction with 4-tolyl isocyanate was successful.

(36) IR spectroscopy: v=3305 (b, vw, v[NH]), 2970 (w), 2929 (w), 2899 (w), 2868 (w), 1731 (w, v[CO]), 1600 (w), 1536 (b, w), 1453 (b, w), 1406 (w), 1373 (w), 1343 (w), 1315 (w), 1297 (w), 1223 (m), 1209 (w), 1093 (vs), 1004 (m), 933 (m), 853 (w), 818 (m), 768 (vw), 660 (vw), 510 (w) cm.sup.1.

(37) The IR spectrum is identical neither to the IR spectrum of paraformaldehyde nor to the IR spectrum of PPG-1000. The occurrence of an additional band at 968 cm.sup.1 indicates the presence of oxymethylene groups and hence the incorporation of formaldehyde. The NH and CO stretch vibrations can be attributed to carbamate units. The occurrence of these bands demonstrates that the reaction of the terminal OH groups with tolyl isocyanate was successful. The absence of an NCO band at 2261 cm.sup.1 shows that no free 4-tolyl isocyanate is present in the product.

Reference Example 1

Preparation of a Bifunctional Polypropylene Oxide-Polyoxymethylene Block Copolymer Using Paraformaldehyde as Formaldehyde Source and In Situ Modification of the Resultant Product with 4-Tolyl Isocyanate

(38) Reference example 1 was conducted analogously to example 1, except that the formaldehyde source used in the polymerization was paraformaldehyde rather than gaseous formaldehyde.

(39) A 300 mL stainless steel reactor with sparging stirrer was initially charged under argon with a mixture of 30.34 g (1.01 mmol) of paraformaldehyde, 20.02 g (20.02 mmol) of PET-1 and 70 mg (0.111 mmol) of dibutyltin dilaurate (DBTL), and the reactor was injected with CO.sub.2 to a pressure between 17 and 19 bar. Subsequently, the reactor was heated to an internal temperature of 60 C. On attainment of the temperature, the pressure was adjusted to 20 bar with CO.sub.2 and the reaction mixture was stirred at 60 C. for 4.7 h. Thereafter, the reactor was cooled to room temperature and the pressure was released. Subsequently, 5.05 mL (5.33 g, 40.0 mmol) of 4-tolyl isocyanate were metered in at a flow rate of 1 mL/min at internal temperature 40 C. while stirring. After the addition had ended, the reaction mixture was stirred at 60 C. for a further 16 h. After the reactor had been cooled down, 42.20 g of a waxy substance were removed.

(40) Viscosity: 20.28 Pa.Math.s

(41) The viscosity of the product obtained in reference example 1 was an order of magnitude higher than the viscosity of the product obtained in example 1.

(42) IR spectroscopy: v=3302 (b, vw, v[NH]), 2972 (w), 2922 (w), 2869 (w), 1730 (b, w, v[CO]), 1640 (vw), 1598 (vw), 1537 (b, w), 1406 (b, vw), 1406 (vw), 1374 (w), 1344 (vw), 1316 (vw), 1297 (vw), 1284 (vw), 1236 (w, PFA), 1209 (vw), 1087 (vs), 1038 (w, PFA), 963 (b, m, PFA), 928 (b, s, PFA), 908 (s, shoulder, PFA), 816 (m), 725 (w, PFA), 629 (m, PFA), 509 (w), 453 (w, PFA) cm.sup.1.

(43) The comparison of the IR spectrum of the product obtained in reference example 1 with the IR spectrum of paraformaldehyde shows that the product obtained in reference example 1, unlike the product obtained in example 1, still contained paraformaldehyde. This is indicated by the characteristic bands, some of them strong, for paraformaldehyde (PFA) at 1236, 1038, 963, 928, 908, 725, 629 and 453 cm.sup.1.

(44) The product obtained, unlike the product obtained in example 1, was not entirely soluble in chloroform. 1.74 g of the resultant product mixture were taken up in chloroform and filtered through a paper filter. The filtration residue isolated after drying was 0.19 g of an insoluble solid. The sample thus contained at least 11% by weight of an insoluble by-product.

(45) For the chloroform-soluble fraction, by gel permeation chromatography (GPC) against polypropylene glycol standards, a number-average molecular weight M.sub.n=753 g/mol and a polydispersity index PDI=1.34 were determined. The GPC showed, as well as a higher molecular weight fraction (>633 g/mol, 81.5% by weight) having a number-average molecular weight M.sub.n=1098 g/mol and a polydispersity index PDI=1.05, a low molecular weight fraction (<633 g/mol, 18.5% by weight) having a broad molecular weight distribution. This low molecular weight fraction does not arise from the reaction of PET-1 with formaldehyde and was thus an unwanted by-product.

(46) For the CDCl.sub.3-soluble fraction, the following NMR data were measured:

(47) .sup.1H NMR spectroscopy (400 MHz, CDCl.sub.3): =1.13 (bs, 24.47H, PET-1-CH.sub.3), 1.28 (bs, 1.44H), 2.29 (bs, 3.00H, Tol-CH.sub.3), 2.45 (bs, 0.37H), 3.12-3.82 (m, 24.69H, PET-1-CH/PET-1-CH.sub.2), 3.82-4.14 (m, 0.70H), 4.69-5.24 (kb, 1.99H, OCH.sub.2O/PET-1-CH(CH.sub.3)OCH.sub.2O O/PET-1-CH.sub.2OCH.sub.2O), 5.42 (bs, 1.02H, CH.sub.2O), 7.08 (bs, 2.95H, Tol-CH.sub.ar), 7.29 (bs, 1.97H, Tol-CH.sub.ar), 7.51 (s, 0.07H), 9.71 (s, 0.01H) ppm.

(48) .sup.13C APT NMR spectroscopy (100 MHz, CDCl.sub.3): =17.0 (), 17.3 (), 17.5 (), 17.7 (), 17.8 (), 18.1 (), 18.2 (), 18.5 (), 20.8 (, Tol-CH.sub.3), 70.6 (), 71.8 (+), 72.9 (+), 73.4 (+), 73.9 (+), 74.1 (+), 75.0 (), 75.1 (), 75.2 (), 75.4 (), 75.6 (), 75.7 (), 75.8 (+), 75.9 (+), 85.6 (+, OCH.sub.2O), 86.1 (+, OCH.sub.2O) 88.8 (+, OCH.sub.2O), 92.4 (+, OCH.sub.2O), 119.0 (, Tol-CH.sub.ar), 119.5 (, Tol-CH.sub.ar), 122.9 (, Tol-CH.sub.ar), 129.5 (, Tol-CNH), 135.7 (+), 152.1-154.1 (+, many signals, Tol-NHC(O)O) ppm.

(49) The NMR spectroscopy data of the CDCl.sub.3-soluble fraction show that an NCO-modified polyoxymethylene block copolymer was obtained.

(50) The product obtained using paraformaldehyde as formaldehyde source had significantly increased viscosity and lowered solubility compared to the inventive product obtained using gaseous formaldehyde (example 1). The IR spectroscopy data demonstrate that the product obtained in reference example 1 was contaminated with paraformaldehyde. The GPC data show that the product obtained in reference example 1 additionally contained low molecular weight by-products. The use of gaseous formaldehyde thus allows the inventive products to be obtained in higher purity.

Reference Example 2

Preparation of a Bifunctional Polypropylene Oxide-Polyoxymethylene Block Copolymer Using Aqueous Formaldehyde Solution and In Situ Modification of the Resultant Product with 4-Tolyl Isocyanate

(51) Reference example 2 was conducted analogously to example 1, except that the formaldehyde source used in the polymerization was aqueous formaldehyde solution rather than gaseous formaldehyde.

(52) A 300 mL stainless steel reactor with sparging stirrer was initially charged under argon with a mixture of 83.09 g of a 35.5% aqueous formaldehyde solution (corresponding to 1.01 mol of formaldehyde), 20.02 g (20.02 mmol) of PET-1 and 70 mg (0.111 mmol) of dibutyltin dilaurate (DBTL), and the reactor was injected with CO.sub.2 to a pressure between 17 and 19 bar. Subsequently, the reactor was heated to an internal temperature of 60 C. On attainment of the temperature, the pressure was adjusted to 20 bar with CO.sub.2 and the reaction mixture was stirred at 60 C. for 4.7 h. Thereafter, the reactor was cooled to room temperature and the pressure was released. Subsequently, 5.05 mL (5.33 g, 40.0 mmol) of 4-tolyl isocyanate were metered in at a flow rate of 1 mL/min at internal temperature 40 C. while stirring. After the addition had ended, the reaction mixture was stirred at 60 C. for a further 16 h. After the reactor had been cooled down, 88.12 g of a yellow-reddish, inhomogeneous liquid mixture having colorless solid components were removed.

(53) No viscosity was measurable because of the inhomogeneity of the product.

(54) IR spectroscopy: v=3400 (b, w, v[OH]), 3308 (b, w, v[NH]), 2968 (m), 2903 (m), 2872 (m), 2336.9 (vw), 1734 (w, v[CO]), 1638 (w), 1616 (w), 1595 (w), 1540 (w), 1515 (m), 1452 (w), 1406 (w), 1373 (m), 1347 (w), 1315 (w), 1295 (w), 1229 (w), 1210 (w), 1087 (vs), 1011 (s), 926 (m), 867 (w). 852 (w), 815 (m), 778 (w), 751 (w), 727 (w), 669 (w), 640 (m), 582 (m), 568 (m), 549 (w), 533 (w), 506 (m), 488 (w), 450 (w), 637 (w), 424 (vw), 409 (vw) cm.sup.1.

(55) The IR spectrum of the product obtained in reference example 2 differed fundamentally from the IR spectrum of the product obtained in example 1. The IR spectrum of the product obtained in reference example 2 showed additional signals, for example at 3400, 2337, 1638, 1616, 1373, 867, 751 cm.sup.1, and a fundamentally different fingerprint region between 400 and 700 cm.sup.1. No assignment of these bands was possible. A strong OH band at 3400 cm.sup.1 compared to the product from example 1 indicated that significant amounts of water or free OH groups were present in the product. The IR spectrum thus showed significant contamination with by-products.

(56) Gel permeation chromatography (GPC) of the chloroform-soluble fraction showed an inhomogeneous molecular weight distribution. As well as a higher molecular weight fraction (>602 g/mol, 51% by weight) having a number-average molecular weight M.sub.n=1033 g/mol and a polydispersity index PDI=1.05 (calibrated against polypropylene glycol standards), a low molecular weight fraction (<602 g/mol, 49% by weight) having a broad molecular weight distribution was detected. This low molecular weight fraction does not arise from the reaction of PET-1 with formaldehyde and was thus an unwanted by-product.

(57) For the CDCl.sub.3-soluble fraction, the following NMR data were measured:

(58) .sup.1H NMR spectroscopy (400 MHz, CDCl.sub.3): =0.89-0.94 (bs, 0.19H), 0.95-1.16 (m, 29.26H, PET-1-CH.sub.3), 1.16-1.25 (m, 0.54H, PET-1-CH.sub.3), 2.09-2.29 (kb, 3.00H, Tol-CH.sub.3), 2.35 (bs, 0.20H), 2.79 (d, J=8.5 Hz), 2.94 (bs, 2.36H), 3.06-3.16 (m, 0.67H), 3.16-3.77 (kb, 39.80H, PET-1-CH/PET-1-CH.sub.2), 3.77-3.92 (m, 0.83H, PET-1-CH/PET-1-CH.sub.2), 3.92-4.03 (m, 0.13H), 4.32-4.38 (m, 0.19H), 4.49 (s, 0.67H), 4.55-4.73 (kb, 7.06H, OCH.sub.2O/PET-1-CH(CH.sub.3)OCH.sub.2O O/PET-1-CH.sub.2OCH.sub.2O), 4.73-5.00 (kb, 11.76H, CH.sub.2O), 5.03 (s, 0.39H, CH.sub.2O), 5.14-5.15 (m, 0.08H, CH.sub.2O), 5.26 (s, 0.39H, CH.sub.2O), 5.26-5.40 (m, 0.40H, CH.sub.2O), 6.29 (d, J=15.2 Hz, 0.052H), 6.55 (d, J=8.5 Hz, 0.015H), 6.60 (s, 0.016H), 6.63 (s, 0.0064H), 6.66-6.79 (m, 0.22H), 6.79-6.87 (m, 0.24H), 6.87-7.12 (kb, 2.47H), 7.31 (bs, 0.10H), 7.43 (bs, 0.14H), 7.49 (bs, 0.12H), 7.65 (bs, 0.14H), 7.93 (s, 0.0066H) ppm.

(59) The .sup.1H NMR spectrum shows that, as well as polyoxymethylene block copolymers, a multitude of by-products were obtained. In the aromatic region between 6.2 and 8.0 ppm, unlike the product obtained in example 1, a multitude of signals was found. No multiplet in the region of 7.14-7.32 ppm with an integral ratio of about 1.5-2 to 3 in relation to the Tol-CH.sub.3 signal at 2.09-2.29 ppm was detected. This shows that the reaction of the polyoxymethylene block copolymer with 4-tolyl isocyanate was incomplete. Instead, a predominant portion of the 4-tolyl isocyanate had reacted unspecifically to give various by-products (for example in the reaction with water with elimination of CO.sub.2 to give aniline and conversion products thereof with formaldehyde).

(60) .sup.13C APT NMR spectroscopy (100 MHz, CDCl.sub.3): =16.1 (), 16.2 (), 16.7 (), 16.9 (), 17.0 (), 17.1 (), 17.2 (), 17.6 (), 17.8 (), 17.9 (), 18.1 (), 18.3 (), 18.4 (), 20.3 (), 20.4 (), 20.6 (), 21.0 (), 50.1 (), 54.3 (), 54.8 (), 54.9 (), 55.4 (), 55.5 (), 55.6 (), 55.7 (), 55.7 (), 55.8 (), 56.5 (), 57.3 (), 65.7 (), 67.1 (), 67.1 (), 86.1 (+), 69.4 (+), 71.0 (+), 71.0 (), 72.8 (+), 73.0 (+), 73.2 (+), 73.3 (), 73.4 (+), 73.5 (), 73.7 (), 73.8 (+), 74.2 (), 74.3 (+), 74.3 (+), 74.4 (+), 74.6 (), 74.6 (), 74.7 (), 74.8 (), 74.9 (), 74.9 (), 75.1 (), 75.2 (), 75.2 (), 75.2 (), 75.3 (), 75.4 (), 75.6 (+), 75.7 (+), 76.0 (+), 76.3 (), 76.3 (), 76.4 (), 76.5 (), 76.6 (), 78.6 (+), 79.5 (+), 79.5 (+), 82.1 (+), 82.6 (+), 83.3 (+), 84.2 (+), 84.4 (+), 85.6 (+), 85.6 (+), 86.3 (+), 86.7 (+), 86.8 (+), 86.9 (+), 87.0 (+), 88.1 (+), 88.3 (+), 88.5 (+), 88.7 (+), 88.8 (+), 89.0 (+), 89.2 (+), 89.4 (+), 89.5 (+), 89.7 (+), 89.9 (+), 89.9 (+), 90.1 (+), 90.5 (+), 90.5 (+), 90.8 (+), 91.2 (+), 91.3 (+), 92.1 (+), 92.5 (+), 92.6 (+), 92.7 (+), 93.1 (+), 93.2 (+), 93.3 (+), 93.4 (+), 93.5 (+), 93.6 (+), 94.9 (+), 97.3 (+), 114.6 (), 114.7 (), 114.8 (), 117.0 (), 117.6 (), 117.6 (), 118.9 (), 119.4 (), 120.1 (), 120.4 (), 120.9 (), 127.2 (), 128.0 (), 128.1 (), 129.2 (), 129.3 (), 129.4 (), 129.5 (), 129.5 (), 129.6 (), 129.6 (), 130.8 (), 130.9 (), 131.3 (+) ppm.

(61) The .sup.1H NMR and .sup.13C APT NMR spectra of the soluble fractions of the product obtained in reference example 2 were not identical to the .sup.1H NMR and .sup.13-C APT NMR spectra of the product obtained in example 1. The NMR spectra showed that the product obtained in reference example 2 was a complex product mixture which, as well as polyoxymethylene block copolymers, contained a multitude of by-products. A multitude of signals in the aromatic range (6.2 to 8.0 ppm in the .sup.1H NMR spectrum, 114 to 132 ppm in the .sup.13C NMR spectrum) shows that the reaction of the polyoxymethylene block copolymer with 4-tolyl isocyanate was incomplete and it had reacted instead in an unspecific manner to give various by-products.

(62) From a portion of 44.03 g of the resultant product mixture, the volatile components were removed at 60 C. under a reduced pressure of 30 mbar. 12.81 g of a waxy residue were obtained, which was not entirely soluble in chloroform. 1.8 g of this residue were taken up in chloroform and filtered through a paper filter. After the volatile components of the filtrate had been removed under reduced pressure, 0.78 g of a waxy substance was obtained. The filtration residue isolated after drying was 0.89 g of an insoluble solid. The sample thus contained at least 49% by weight of an insoluble by-product.

(63) For the filtrate residue, a viscosity of 2.395 Pa.Math.s was determined. The viscosity is distinctly increased compared to the product obtained in example 1.

(64) In reference example 2, unlike example 1, an inhomogeneous product mixture was obtained, which contained firstly a high water content and secondly insoluble solid fractions. The IR spectrum showed the occurrence of by-products. By GPC, for the chloroform-soluble fraction, a high level of low molecular weight by-products was detected. The .sup.1H NMR spectrum of the soluble fraction showed that the reaction with 4-tolyl isocyanate to give NCO-modified polyoxymethylene block copolymers was incomplete and a multitude of by-products was obtained. The .sup.13C APT NMR spectrum also demonstrated a high level of by-products. Comparison with example 1 shows that, on use of aqueous formaldehyde solution, the reaction with the isocyanate proceeds only incompletely and the isocyanate forms unwanted by-products unless the aqueous constituents are removed before this step.

Example 2

Preparation of a Bifunctional Polypropylene Oxide-Polyoxymethylene Block Copolymer and Ex Situ Modification of the Resultant Product with 4-Tolyl Isocyanate

(65) Preparation of a bifunctional polypropylene oxide-polyoxymethylene block copolymer:

(66) Reactor 1 was initially charged with a suspension of 30.24 g (1.008 mol) of paraformaldehyde, 0.65 g (1.99 mmol) of 4-dodecylbenzenesulfonic acid and 8.37 g of 3 molecular sieve in 30 ml of undecane. Reactor 2 contained a solution of 60.0 mg (0.095 mmol) of dibutyltin dilaurate (DBTL) in 20.01 g (20.01 mmol) of PET-1. Via a bypass line connected to MFC 1, the whole system with the bridge open was pressurized to 20 bar with CO.sub.2. Then the bridge was closed and the pressure in reactor 1 was reduced to 5 bar by means of a gas outlet valve. The reaction mixture in reactor 1 was heated to 125 C. while stirring with the bridge shut off, and the reaction mixture in reactor 2 to 60 C. while stirring. The bridge temperature was adjusted to 170 C. On attainment of the reaction temperature, the pressure in reactor 2 was adjusted to a value between 17 and 19 bar. The pressure in reactor 1 was adjusted to 20 bar with CO.sub.2 via the bypass. The bypass line was closed and a constant argon flow rate {circumflex over (V)}.sub.out={circumflex over (V)}.sub.in, 47.6 ml/min was established using the mass flow regulators. Directly thereafter, the bridge was opened. After 4.2 h, the bridge was closed, the system was cooled to room temperature and the pressure was released separately in reactor 1 and reactor 2.

(67) Weighing of reactor 2 showed an increase in weight of 1.58 g for the reaction, corresponding to a formaldehyde transfer of 52.6 mmol. Thus, the PET-1 used as monomer was extended by an average of 2.63 formaldehyde units per molecule.

(68) Viscosity: 0.1405 Pa.Math.s

(69) By gel permeation chromatography (GPC) against polystyrene standard, a number-average molecular weight M.sub.n=1015 g/mol and a polydispersity index PDI=1.08 were determined. The small increase in the measured number-average molecular weight compared to the measured number-average molecular weight of the PET-1 used as starter is attributable to different interaction of the polymer chains with the column material.

(70) .sup.1H NMR spectroscopy (400 MHz, CDCl.sub.3): =0.56-1.02 (m, 51.72H, CH.sub.3), 2.79-3.60 (kb, 51.79H, PET-1-CH/PET-1-CH.sub.2), 4.38 (bs, 0.104H, OCH.sub.2O), 4.88 (bs, 0.106H, OCH.sub.2O), 4.73-4.75 (m, 0.986H, OCH.sub.2O) ppm.

(71) .sup.13C APT NMR spectroscopy (100 MHz, CDCl.sub.3): =13.4 (), 16.4 (), 16.4 (), 16.5 (), 16.5 (), 16.6 (), 16.6 (), 16.7 (), 17.3 (), 17.4 (), 17.5 (), 17.6 (), 17.8 (), 17.9 (), 18.1 (), 18.2 (), 18.3 (), 18.3 (), 21.9 (+), 28.6 (+), 28.9 (+), 29.0 (+), 31.1 (+), 72.3 (+), 72.6 (+), 72.9 (+), 73.1 (+), 73.9 (+), 74.0 (+), 74.1 (), 74.1 (), 74.2 (), 74.2 (), 74.3 (), 74.4 (), 74.5 (), 74.7 (), 74.7 (), 75.0 (+, 0-CH.sub.2O). 88.3 (+. OCH.sub.2O), 88.8 (+, OCH.sub.2O), 89.6 (+, OCH.sub.2O), 92.7 (+, OCH.sub.2O) ppm.

(72) The signals in the .sup.1H NMR spectrum between 4.38 and 4.75 ppm, and between 75.0 and 92.7 ppm in the .sup.13C APT NMR spectrum (methylene groups having positive polarity), indicate the presence of oxymethylene units as well as polypropylene oxide units in the product. The presence of several oxymethylene signals with different chemical shifts indicates the different chain lengths n of the polyoxymethylene units (CH.sub.2O), and hence demonstrates that inventive polypropylene oxide-polyoxymethylene block copolymers having 1 oxymethylene group per polyoxymethylene unit were obtained.

(73) IR: v=3455 (b, vw, v[OH]), 2970 (w), 2930 (w), 2868 (w), 1453 (w), 1373 (w), 1344 (w), 1297 (w), 1260 (vw), 1091 (vs), 1013 (w), 968 (w), 928 (w), 864 (w), 838 (w), 665 (vw), 581 (vw), 523 (vw), 469 (vw), 436 (vw), 427 (vw), 410 (vw) cm.sup.1.

(74) The occurrence of a new band at 968 cm.sup.1 indicates the presence of oxymethylene groups.

(75) Ex situ modification of the polypropylene oxide-polyoxymethylene block copolymer with 4-tolyl isocyanate:

(76) A round-bottom flask was initially charged with 5.0 g of the resultant polypropylene oxide-polyoxymethylene block copolymer, and 1.16 mL (1.22 g, 9.16 mmol) of 4-tolyl isocyanate were added. The reaction mixture was stirred for a further 2 h. 6.20 g of a viscous, colorless oil were obtained.

(77) Viscosity: 2.543 Pa's

(78) By gel permeation chromatography (GPC) against polystyrene standard, a number-average molecular weight M.sub.n=1138 g/mol and a polydispersity index PDI=1.05 were determined.

(79) .sup.1H NMR (400 MHz, CDCl.sub.3): =0.75-0.82 (m, 0.41H), 0.91-1.13 (m, 27.78H, PET-1-CH.sub.3), 1.13-1.29 (m, 3.93H, PET-1-CH.sub.3), 2.18 (s, 3.00H, Tol-CH.sub.3), 3.12-3.72 (kb, 29.39H, PET-1-CH/PET-1-CH.sub.2), 3.72-3.92 (m, 0.38H, PET-1-CH/PET-1-CH.sub.2), 4.86-5.00 (m, 0.75H, OCH.sub.2O/PET-1-CH(CH.sub.3)OCH.sub.2O/PET-1-CH.sub.2OCH.sub.2O), 5.04 (s, 0.58H, OCH.sub.2O), 5.25-5.38 (m, 0.11H, OCH.sub.2O), 6.97 (d, J=7.9 Hz, 2.00H, Tol-CH.sub.ar), 7.16-7.29 (m, 2.10H, Tol-CH.sub.ar) ppm.

(80) .sup.13C APT NMR (400 MHz, CDCl.sub.3): =14.0 (), 16.9 (), 17.0 (), 17.2 (), 17.2 (), 17.3 (), 17.9 (), 17.9 (), 18.0 (), 18.1 (), 18.4 (), 20.6 (, Tol-CH.sub.3), 22.5 (+), 29.2 (+), 29.5 (+), 29.5 (+), 31.7 (+), 65.4 (), 67.0 (), 67.1 (), 70.2 (), 70.3 (), 71.6 (+), 71.7 (+), 71.8 (+), 72.7 (+), 72.8 (+), 72.9 (+), 73.0 (+), 73.2 (+), 73.4 (+), 73.7 (+), 74.3 (+), 74.4 (+), 74.8 (), 74.9 (), 75.0 (), 75.0 (), 75.2 (), 75.2 (), 75.4 (), 75.5 (), 88.5 (+, OCH.sub.2O), 93.4 (+, OCH.sub.2O), 118.6 (, Tol-CH.sub.ar), 118.8 (, Tol-CH.sub.ar), 129.2 (, Tol-CH.sub.ar), 131.4 (+), 132.3 (+, Tol-CNH), 135.7 (+, Tol-CCH.sub.3), 136.8 (+), 153.2 (+, OC(O)NH-Tol) ppm.

(81) The signals between 4.85 and 5.38 ppm in the .sup.1H NMR spectrum, and at 88.5 and 93.4 in the .sup.13C APT NMR spectrum show that the product contains polyoxymethylene units.

(82) Both the .sup.1H NMR and the .sup.13C APT NMR spectra show that the reaction of the polypropylene oxide-polyoxymethylene copolymer obtained and isolated beforehand with 4-tolyl isocyanate to give polyurethane-analogous compounds was successful. The comparison of the integrals for the methyl groups Tol-CH.sub.3 and PPG-CH.sub.3 gives a ratio of 0.095 Tol-CH.sub.3 to 1 PPG-CH.sub.3. For an average chain length of 17.02 (CH(CH.sub.3)CH.sub.2O) units per molecule, this gives an average of 1.610 4-tolyl carbamate units per molecule. The reaction of the polyoxymethylene block copolymer with 4-tolyl isocyanate accordingly proceeded with a conversion of 80%/o.

(83) IR: v=3301 (b, vw, v[NH]), 2971 (w), 2929 (w), 2868 (w), 1728 (w, v[CO]), 1599 (w), 1534 (w), 1453 (w), 1407 (w), 1373 (w), 1344 (w), 1315 (w), 1297 (w), 1224 (m), 1209 (w), 1091 (vs), 1017 (m), 968 (vw), 929 (w), 855 (vw), 818 (m), 768 (vw), 711 (vw), 666 (vw), 580 (vw), 543 (vw), 510 (w), 465 (vw) cm.sup.1.

(84) The IR spectrum is not identical to the IR spectrum of paraformaldehyde, to the IR spectrum of PET-1 or to the IR spectrum of the starting material. The occurrence of a new band at 968 cm.sup.1 indicates the presence of oxymethylene groups. The NH and CO stretch vibrations can be attributed to carbamate units. The occurrence of these bands demonstrates that the reaction of the terminal OH groups with tolyl isocyanate was successful. The absence of an NCO band at 2261 cm.sup.1 shows that no free 4-tolyl isocyanate was present in the product.

Example 3

Preparation of a Trifunctional Polypropylene Oxide-Polyoxymethylene Block Copolymer and In Situ Modification of the Resultant Product with 4-Tolyl Isocyanate

(85) Reactor 1 was initially charged with a suspension of 30.18 g (1.006 mol) of paraformaldehyde, 0.66 g (2.02 mmol) of 4-dodecylbenzenesulfonic acid and 8.43 g of 3 molecular sieve in 30 ml of undecane. Reactor 2 contained a solution of 110.0 mg (0.174 mmol) of dibutyltin dilaurate (DBTL) in 20.01 g (28.6 mmol) of PET-2. Via a bypass line connected to MFC 1, the whole system with the bridge open was pressurized to 20 bar with argon. Then the bridge was closed and the pressure in reactor 1 was reduced to 5 bar by means of a gas outlet valve. The reaction mixture in reactor 1 was heated to 125 C. while stirring with the bridge shut off, and the reaction mixture in reactor 2 to 60 C. while stirring. The bridge temperature was adjusted to 170 C. On attainment of the reaction temperature, the pressure in reactor 2 was adjusted to a value between 17 and 19 bar. The pressure in reactor 1 was adjusted to 20 bar with CO.sub.2 via the bypass. The bypass line was closed and a constant argon flow rate {circumflex over (V)}.sub.out={circumflex over (V)}.sub.in=72 m/min was established using the mass flow regulators. Directly thereafter, the bridge was opened. After 4.8 h, the bridge was closed, the system was cooled to room temperature and the pressure was released separately in reactor 1 and reactor 2. Subsequently, 10.7 mL (11.30 g, 84.9 mmol) of 4-tolyl isocyanate were introduced into reactor 2 at a flow rate of 1 mL/min while stirring at an internal temperature of 40 C. After the addition had ended, the reaction mixture in reactor 2 was stirred at 60 C. for a further 16 h. Weighing of reactor 2 before the removal of the product showed an increase in weight of 3.51 g (difference in mass minus the mass of the isocyanate fed in) for the reaction, which corresponds to a transfer of 3.51 g (116.9 mmol) of gaseous formaldehyde. 28.79 g of a viscous, colorless oil were removed from reactor 2.

(86) As a result of transfer of 3.51 g (116.9 mmol) of formaldehyde, the PET-2 used as oligomer was extended by an average of 4.09 formaldehyde units per molecule, or 1.36 formaldehyde units per chain end.

(87) Viscosity: 14.65 Pa's

(88) By gel permeation chromatography (GPC) against polystyrene standard, a number-average molecular weight M.sub.n=816 g/mol and a polydispersity index PDI=1.07 were determined.

(89) .sup.1H-NMR (400 MHz, CDCl.sub.3): =0.73-0.81 (m, 0.51H), 0.91-1.11 (m, 10.48H, PET-2-CH.sub.3), 1.11-1.26 (m, 3.93H, PET-2-CH.sub.3), 2.09-2.30 (m, 3.00H, Tol-CH.sub.3), 3.12-3.71 (kb, 13.80H, PET-2-CH/PET-2-CH.sub.2), 3.71-3.82 (bs, 0.40H, PET-2-CH/PET-2-CH.sub.2), 4.65 (s, 0.04H, OCH.sub.2O), 4.79 (s, 0.01H, OCH.sub.2O), 4.83 (s, 0.01H. OCH.sub.2O), 4.84-4.98 (bs, 0.78H, OCH.sub.2O/PET-2-CH(CH.sub.3)OCH.sub.2O O/PET-2-CH.sub.2OCH.sub.2O), 5.05 (s, 0.83H, OCH.sub.2O), 5.24-5.35 (m, 0.17H, OCH.sub.2O), 6.92-7.04 (m, 2.16H, Tol-CH.sub.ar), 7.08-7.29 (m, 2.10H, Tol-CH.sub.ar) ppm.

(90) .sup.13C APT NMR (400 MHz, CDCl.sub.3): =14.1 (), 17.0 (), 17.3 (), 18.2 (), 18.2 (), 18.5 (), 20.8 (, Tol-CH.sub.3), 22.7 (+), 29.4 (+), 29.7 (+), 29.7 (+), 31.9 (+), 65.6 (), 67.1 (), 67.2 (), 67.3 (), 69.5 (+), 69.8 (+), 70.5 (), 70.7 (), 70.7 (), 71.5 (+), 71.8 (+), 72.9 (+), 73.0 (+), 73.1 (+), 73.4 (+), 74.3 (+), 74.4 (+), 74.5 (+), 75.0 (), 75.2 (), 75.6 (), 75.7 (), 75.9 (), 76.0 (), 93.6 (+, OCH.sub.2O), 118.0 (, Tol-CH.sub.ar), 118.7 (, Tol-CH.sub.ar), 119.6 (, Tol-CH.sub.ar), 129.4 (, Tol-CH.sub.ar), 129.7 (, Tol-CH.sub.ar), 132.6 (+, Tol-CNH), 135.7 (+, Tol-CCH.sub.3), 153-154 (+, Tol-NHC(O)O) ppm.

(91) The signals for oxymethylene groups OCH.sub.2O in the .sup.1H and .sup.13C APT NMR spectrum show that a block copolymer consisting of polypropylene oxide and polyoxymethylene units is present.

(92) Both the .sup.1H NMR and the .sup.13C APT NMR spectra show that the reaction of the polypropylene oxide-polyoxymethylene copolymer with 4-tolyl isocyanate to give polyurethane-analogous compounds was successful. The comparison of the integrals for the methyl groups Tol-CH.sub.3 and PPG-CH.sub.3 gives a ratio of 0.208 Tol-CH.sub.3 to 1 PPG-CH.sub.3. For an average content of 11.26 (CH(CH.sub.3)CH.sub.2O) units per molecule, this gives an average of 2.342 4-tolyl carbamate units per molecule. The reaction of the polyoxymethylene block copolymer with 4-tolyl isocyanate accordingly proceeded with a conversion of 78%.

(93) IR: v=3303 (b, w, v[NH]), 2971 (w), 2928 (w), 2869 (w), 1727 (m, v[CO]), 1638 (w), 1596 (m), 1530 (m), 1453 (w), 1407 (w), 1374 (w), 1345 (w), 1315 (m), 1296 (w), 1224 (m), 1209 (m), 1160 (m), 1080 (vs), 1018 (m), 967 (w), 930 (w), 816 (m), 768 (w), 751 (vw), 708 (vw), 640 (vw), 570 (vw), 523 (vw), 507 (m), 466 (w), 451 (vw) cm.sup.1.

(94) The IR spectrum is not identical to the IR spectrum of paraformaldehyde or to the IR spectrum of PET-2. The occurrence of a new band at 967 cm.sup.1 indicates the presence of oxymethylene groups. The NH and CO stretch vibrations can be attributed to carbamate units. The occurrence of these bands shows that the reaction of the terminal OH groups with 4-tolyl isocyanate was successful. The absence of an NCO band at 2261 cm.sup.1 shows that no free 4-tolyl isocyanate is present in the product.