Reactive thermoplastic polyurethane based on blocked isocyanates

Abstract

A method for producing a shaped body, containing: producing the shaped body from a composition by a powder-based layer construction process, wherein the composition contains a thermoplastic polyurethane, obtained by reacting a polyisocyanate composition and a polyol composition, the thermoplastic polyurethane is solid at least in a temperature region below 50° C. and has end groups selected from the group consisting of first end groups and second end groups, wherein the first end groups are optionally eliminated at a first temperature, and the second end groups are optionally eliminated at a second temperature, to form reactive groups on the thermoplastic polyurethane that optionally enter into a reaction with functional groups of the thermoplastic polyurethane or functional groups of a further component of the composition, and wherein the first temperature and the second temperature are each greater than or equal to 60° C.

Claims

1. A method for producing a shaped body, the method comprising: producing the shaped body from a composition by localized heating in a powder-based layer construction process, wherein the composition comprises a thermoplastic polyurethane, obtained by a method comprising reacting at least one polyisocyanate composition and at least one polyol composition, wherein the thermoplastic polyurethane is solid at least in a temperature region below 50° C. and has end groups selected from the group consisting of first end groups and second end groups, wherein the first end groups are optionally eliminated at a first temperature, and the second end groups are optionally eliminated at a second temperature, to form reactive groups on the thermoplastic polyurethane that optionally enter into a reaction with functional groups of the thermoplastic polyurethane or functional groups of a further component of the composition, and wherein the first temperature and the second temperature are each greater than or equal to 60° C.

2. The method according to claim 1, wherein a total content of the first end groups and the second end groups is in a range from 0.01 to 50 mol% based on a content of urethane groups in the thermoplastic polyurethane.

3. The method according to claim 1, wherein the composition further comprises at least one chain extender selected from the group consisting of compounds having at least two groups that are reactive toward isocyanate groups.

4. The method according claim 1, wherein the at least one polyol composition comprises at least one chain extender selected from the group consisting of compounds having at least two groups that are reactive toward isocyanate groups.

5. The method according to claim 3, wherein the at least one chain extender is selected from the group consisting of a diamine and a diol, having a molecular weight of up to 500 g/mol.

6. The method according to claim 4, wherein the at least one chain extender is selected from the group consisting of a diamine and a diol, having a molecular weight of up to 500 g/mol.

7. The method according to claim 1, wherein the thermoplastic polyurethane has a molecular weight in a range from 2000 to 50 000 g/mol, determined by means of GPC.

8. The method according to claim 1, wherein the at least one polyisocyanate composition comprises at least one isocyanate selected from the group consisting of diphenylmethane 2,2′-, 2,4′- and/or 4,4′-diisocyanate, naphthylene 1,5-diisocyanate, tolylene 2,4- and/or 2,6-diisocyanate, 3,3′-dimethyl-4,4′-diisocyanatodiphenyl, p-phenylene diisocyanate, hexamethylene 1,6-diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane and methylenedicyclohexyl 4,4′-, 2,4′- and/or 2,2′diisocyanate, and 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane and a derivative thereof.

9. The method according to claim 1, wherein the at least one polyol composition comprises a polyol selected from the group consisting of a polyether, a polyester, a polycaprolactone and a polycarbonate.

10. The method according to claim 1, wherein the thermoplastic polyurethane is present in a form of a powder with an average particle size d50 in a range of from 10 to 500 μm.

11. A method for producing a shaped body, the method comprising: producing the shaped body from a composition by localized heating in a powder-based layer construction process, wherein a composition comprises a thermoplastic polyurethane obtained by a process comprising reacting at least one polyisocyanate composition and at least one polyol composition, wherein the at least one polyisocyanate composition comprises an isocyanate having first end groups that are optionally eliminated at a first temperature to form reactive groups, the at least one polyol composition comprises a polyol having end groups that are optionally eliminated at a second temperature to form reactive groups, or the at least one polyisocyanate composition comprises an isocyanate having the first end groups and the polyol composition comprises a polyol having the second end groups that are both optionally eliminated at the first temperature and the second temperature and, respectively, to form reactive groups, wherein the first temperature and the second temperature are each greater than or equal to 60° C., and wherein the at least one polyisocyanate composition and the at least one polyol composition are reacted at a temperature that is lower than the first temperature and the second temperature.

12. The method according to claim 11, wherein the thermoplastic polyurethane is in a form of a powder having a median particle size d50 in a range from 10 to 500 μm.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows GPC curves of the polyurethanes obtained by use example 1a, where the molecular weight is plotted in g/mol on the x axis and the normalized intensity in % on the y axis.

(2) FIG. 2 shows GPC curves of the polyurethanes obtained by use example 1b, where the molecular weight is plotted in g/mol on the x axis and the normalized intensity in % on they axis.

(3) FIG. 3 shows GPC curves of the polyurethanes obtained by use example 2a, where the molecular weight is plotted in g/mol on the x axis and the normalized intensity in % on the y axis.

(4) FIG. 4 shows GPC curves of the polyurethanes obtained by use example 2b, where the molecular weight is plotted in g/mol on the x axis and the normalized intensity in % on the y axis.

(5) FIG. 5 shows GPC curves of the polyurethanes obtained by use example 2c, where the molecular weight is plotted in g/mol on the x axis and the normalized intensity in % on the y axis.

(6) FIG. 6 shows GPC curves of the polyurethanes obtained by use example 2d, where the molecular weight is plotted in g/mol on the x axis and the normalized intensity in % on the y axis.

(7) The examples below serve to illustrate the invention, but are in no way restrictive in respect of the subject matter of the present invention.

EXAMPLES

1. Feedstocks

(8) Isocyanate 1: is diphenylmethane 4,4′-diisocyanate (4,4′-MDI), molar mass 250.26 g/mol

(9) Isocyanate 2: is a mixture of diphenylmethane 4,4′-diisocyanate (4,4′-MDI; molar mass 250.26 g/mol), N-[4-[(4-isocyanatophenyl)methyl]phenyl]-2-oxoazepane-1-carboxamides (1CL-4,4′-MDI; molar mass 363.41 g/mol) and 2-oxo-N-[4-[[4-[(2-oxoazepane-1-carbonyl) amino]phenyl]methyl]phenyl]azepane-1-carboxamides (2CL-4,4′-MDI; molar mass 476.24 g/mol) having an NCO value of 18.5%

(10) Isocyanate 3: is a mixture of diphenylmethane 4,4′-diisocyanate (4,4′-MDI; molar mass 250.26 g/mol), (1-methylpropylideneamino)-N-[4-[(4-isocyanatophenyl) methyl]phenyl]carbamates (1MEKO-4,4′-MDI; molar mass 339.39 g/mol) and (1-methylpropylideneamino)-N-[4-[[4-[1-methylpropylideneamino]oxycarbonylamino]phenyl]methyl]phenyl]carbamates (2MEKO-4,4′-MDI; molar mass 424.49 g/mol) having an NCO value of 19.4%

(11) Polymer polyol 1: polyether diol having OH number of about 112 formed from tetrahydrofuran (MW: approx. 1000)

(12) Polymer polyol 2: polyether diol having OH number of about 56 formed from tetrahydrofuran (MW: approx. 2000)

(13) Chain extender 1: is butane-1,4-diol, molar mass 90.12 g/mol

(14) Chain extender 2: is hexane-1,6-diol, molar mass 118.18 g/mol

2. Inventive Examples

(15) It has been found that, surprisingly, by the use of blocked isocyanates in a prepolymer process or as co-isocyanates in a one-shot process in the presence of free chain extenders, solid polyurethanes are preparable which increase in molecular weight at temperatures>100° C., preferably at temperatures>150° C.

2.1 Example 1

(16) TABLE-US-00001 TABLE 1 Formulations 1a and 1b Comparison 1a Comparison 1b Isocyanate 1 [g] 27.7 27.2 Polymer polyol 1 [g] 19.4 19.1 Polymer polyol 2 [g] 38.8 38.2 Caprolactam [g] 7.3 7.2 Chain extender 1 [g] 6.9 Chain extender 2 [g] 8.2

2.1.1 Example 1a

Preparation of the Prepolymer

(17) Isocyanate 1 is initially charged at 60° C. in a 250 ml four-neck neck flask provided with a PT100 thermocouple, nitrogen feed, stirrer and heating mantle, and polymer polyol 1 and 2 are added at this temperature. The reaction mixture was heated to 80° C. and stirred for 2 hours at 80° C. Next, caprolactam was added a little at a time to this reaction mixture and the mixture was stirred for a further 2 h. This resulting prepolymer was then cooled to room temperature and used without further treatment for the subsequent application.

Preparation of the Polyurethane Based on the Prepolymer

(18) The resulting prepolymer was reacted in a glass beaker or tinplate container with chain extender 1 while stirring at 80° C., and a solid white mass was obtained.

2.1.2 Example 1b

Preparation of the Prepolymer

(19) Isocyanate 1 is initially charged at 60° C. in a 250 ml four-neck neck flask provided with a PT100 thermocouple, nitrogen feed, stirrer and heating mantle, and polymer polyol 1 and 2 are added at this temperature. The reaction mixture was heated to 80° C. and stirred for 2 hours at 80° C. Next, caprolactam was added a little at a time to this reaction mixture and the mixture was stirred for a further 2 h. This resulting prepolymer was then cooled to room temperature and used without further treatment for the subsequent application.

Preparation of the Polyurethane Based on Prepolymers

(20) The resulting prepolymer was reacted in a glass beaker or tinplate container with chain extender 2 while stirring at 80° C., and a solid white mass was obtained.

2.1.3 Application of the Examples 1

Use Example 1a

(21) The solid material obtained from example 1a was treated for 5 min at 200° C. Analysis was by means of gel permeation chromatography (GPC) before (1a-1) and after (1a-2) and an increase in molecular weight was observed.

(22) Furthermore, the material obtained from example 1a was firstly heat-treated at 80° C. for 15 h, then treated for 5 min at 200° C. and subsequently heat-treated further for 20 h at 100° C. (1a-3).

(23) TABLE-US-00002 TABLE 2 Molecular weight Example Conditions/further treatment (Mw) [g/mol] 1a-1 —   7000 1a-2 5 min at 200° C. 19 000 1a-3 15 h at 80° C.; 5 min at 66 000 200° C.; 20 h at 100° C.

(24) The results of the GPC measurements are shown in FIG. 1.

Use Example 1b

(25) The solid material obtained from example 1a was treated for 5 min at 200° C. Analysis was by means of gel permeation chromatography (GPC) before (1b-1) and after (1b-2) and an increase in molecular weight was observed.

(26) Furthermore, the material obtained from example 1a was firstly heat-treated at 80° C. for 15 h, then treated for 5 min at 200° C. and subsequently heat-treated further for 20 h at 100° C. (1b-3).

(27) TABLE-US-00003 TABLE 3 Molecular weight Example Conditions/further treatment (Mw) [g/mol] 1b-1 —   9900 1b-2 5 min at 200° C. 30 000 1b-3 15 h at 80° C.; 5 min at 66 000 200° C.; 20 h at 100° C.

(28) The results of the GPC measurements are shown in FIG. 2.

2.2 Example 2

2.2.1 Preparation of Isocyanate 2

(29) Isocyanate 1 (78.6 g) was initially charged at 60° C. in a round-neck flask provided with a PT100 thermocouple, nitrogen feed, stirrer and heating mantle, and caprolactam (21.4 g) was added at this temperature. The reaction mixture was heated to 80° C. and stirred for 45 min at 80° C. Next, the isocyanate 2 obtained here was cooled to room temperature and used without further treatment for the reaction with polymer polyol and chain extender (calculated NCO: 18.5%).

General Process for Preparing the Solid Polyurethane in the One-Shot Process

(30) Polymer polyol 1 is reacted together with chain extender 2, isocyanate 1 and isocyanate 2 while stirring. The resulting reaction mixture is poured out onto a heatable and optionally Teflon-coated table and reacted to completion for approximately 60 minutes at 120° C. The thus obtained polymer sheet is then heat-treated at 80° C. for 15 hours.

(31) TABLE-US-00004 TABLE 4 Formulations 2a-2d Compar- Compar- Compar- Compar- ison 2a ison 2b ison 2c ison 2d Isocyanate 1 [g] 13.1 26.1 39.1 46.8 Isocyanate 2 [g] 49.7 33.3 16.7 6.8 Polymer polyol 1 [g] 83.0 83.0 83.0 83.0 Chain extender 2 [g] 14.8 14.8 14.8 14.8

2.2.2 Application of the Examples 2

Use Examples 2a-2d

(32) The solid material obtained from each of examples 2a-d was analyzed by means of gel permeation chromatography (GPC). Examples 2a-d were then treated for 5 min at 200° C. and subsequently heat-treated for a further 20 h at 100° C. The material was additionally stored at 100° C. for 20 h.

(33) TABLE-US-00005 TABLE 5 Molecular weights (Mw) [g/mol] Conditions/further Compar- Compar- Compar- Compar- treatment ison 2a ison 2b ison 2c ison 2d (1) — 6000   9200 20 000 29 000 (2) 20 h at 100° C. 9300 13 000 28 000 35 000 (3) 5 min at 200° C.; 69 000   62 000 88 000 59 000 20 h at 100° C.

(34) The results of the GPC measurements for examples 2a to 2d are shown in FIGS. 3 to 6.

2.3 Example 3

2.3.1 Preparation of Isocyanate 3

(35) Isocyanate 1 (1.179 kg) was initially charged at 60° C. in a round-neck flask provided with a PT100 thermocouple, nitrogen feed, stirrer and heating mantle, and methyl ethyl ketone oxime (0.247 kg) was added at this temperature. The reaction mixture was heated to 80° C. and stirred for 60 min at 80° C. Next, the isocyanate 3 obtained here was cooled to room temperature and used without further treatment for the reaction with polymer polyol and chain extender (calculated NCO: 19.4%).

General Process for Preparing the Solid Polyurethane in the One-Shot Process

(36) Polymer polyol 1 is reacted together with chain extender 2, isocyanate 1 and isocyanate 3 while stirring. The resulting reaction mixture is poured out onto a heatable and optionally Teflon-coated table and reacted to completion for approximately 60 minutes at 120° C. The thus obtained polymer sheet is then heat-treated at 80° C. for 15 hours.

(37) TABLE-US-00006 TABLE 6 Formulation 3 Comparison 3 Isocyanate 1 [g] 569.1 Isocyanate 3 [g] 78.1 Polymer polyol 1 [g] 1000.0 Chain extender 2 [g] 179.3

2.3.2 Application of Example 3

Use Example 3

(38) In each case, the solid material obtained from example 3 was analyzed by means of gel permeation chromatography (GPC). Example 3 was then treated for 5 min at 200° C. and subsequently heat-treated for a further 20 h at 100° C. The material was additionally stored at various temperatures for 20-24 h.

(39) TABLE-US-00007 TABLE 7 Molecular weights (Mw) [g/mol] Conditions/further treatment Comparison 3 (1) — 44 000 (2) 24 h at 60° C. 45 000 (3) 24 h at 80° C. 51 000 (4) 20 h at 100° C. 96 000 (5) 5 min at 200° C.; 20 h at 100° C. 95 000

3. Properties of the Solid Polyurethane and Resulting Test Specimens

(40) The following properties of the polyurethanes obtained were determined by the methods specified:

(41) Determination of molecular weight: In accordance with the prior art, the molecular weight was ascertained according to DIN55672-2. In this case calibration was performed using PMMA.

(42) NCO Value Determination: Determination of the NCO content was conducted according to EN ISO 11909: primary and secondary amines react with isocyanates to give substituted ureas. This reaction proceeds quantitatively in an excess of amine. At the end of the reaction the excess amine is subjected to potentiometric back-titration with hydrochloric acid.

(43) Determination of Average Particle Size: Determination of average particle size: by means of laser diffraction of wet-dispersed powders according to ISO Standard ISO 13320:2009.

CITED LITERATURE

(44) WO 2015/197515 A1

(45) U.S. Pat. No. 9,453,142

(46) EP 0 089 180 A1

(47) U.S. Pat. No. 4,434,126

(48) “Kunststoffhandbuch”, volume 7, “Polyurethane”, Carl Hanser Verlag, 3rd edition, 1993, chapter 3.1

(49) Kunststoffhandbuch, volume VII, edited by Vieweg and Höchtlen, Carl Hanser Verlag, Munich, 1966 (pp 103-113)

(50) “Protective Groups in Organic Synthesis”, John Wiley & Sons, Inc., 3rd edition, 1999, chapter 2.