EP0730614A1

EP0730614A1 - Process for producing thermoplastic polyurethanes by combined thethermoplastic treatment of a hydroxyl- and an isocyanate polyurethane

Info

Publication number: EP0730614A1
Application number: EP95901379A
Authority: EP
Inventors: Bernd Quiring; Walter Meckel
Original assignee: Bayer AG
Current assignee: Bayer AG
Priority date: 1993-11-26
Filing date: 1994-11-14
Publication date: 1996-09-11
Also published as: PL314586A1; WO1995014723A1; HUT74769A; CA2177168A1; JPH09505325A; HU9601417D0; CZ152096A3

Abstract

A process is disclosed for the production of thermoplastic polyurethanes by the combined thermoplastic treatment of a) a polyurethane and/or polyurethane polycarbamide with free hydroxyl groups and/or amino groups and b) a polyurethane and/or polyurethane polycarbamide obtainable by the isocyanate-polyaddition process with a characteristic number of above 100. The process is characterized by the fact that : i) in the production of component b) the characteristic number is between 110 and 150 and ii) in the thermoplastic treatment of components a) and b), the molar ratio of the theoretical isocyanate surplus of component b) to the free hydroxyl groups and/or amino groups content of component a) ranges from 1.02:1 (mol NCO:mol OH or NH2) to 100:1.

Description

A process for the production of thermoplastic polyurethanes through the combined thermoplastic processing of a hydroxyl and an isocyanate polyurethane

The present invention relates to a process for the production of thermoplastic polyurethanes, according to which a hydroxyl and an isocyanate polyurethane are processed together thermoplastically. The process products show very good properties within wide limits regardless of the mixing ratio.

Thermoplastic polyurethanes (TPU) have been known for a long time. In general, the higher their molecular weights, the better their properties.

Because of the strong dependence of their molecular weights on dosing fluctuations in the manufacturing process, it is not easy to produce these thermoplastics with constant quality.

US Pat. No. 5,089,571 describes a method of how non-specification-compliant thermoplastic polyurethanes can nevertheless be processed to give moldings with good properties. Products containing free hydroxyl groups (hydroxyl polyurethane) are mixed with a TPU which has been produced with a key figure above 100 (ie NCO: OH ratio x 100) (isocyanate polyurethane) and melted, for example by injection molding or extrusion , processed into moldings with high molecular weights and thus good strengths. The hydroxyl polyurethane and / or isocyanate polyurethane can be a TPU that was not obtained in accordance with the specification due to incorrect metering or thermal degradation, or it could also have been produced specifically for the two-component thermoplastic processing with corresponding functional groups According to the teaching of this US Pat. No. 5,089,571, both components must meet strict requirements with regard to their molecular weights, namely the average molecular weight ^ of the free isocyanate-containing component must be between 100,000 and 200,000, that of the hydroxyl-containing reaction partner is between 30,000 and 150,000 and Both components should be mixed in such a way that the resulting end product has a high molecular weight. According to the teaching of the abovementioned US patent (inter alia column 3, lines 3 et seq.), This is achieved if a calculated molar NCO: OH ratio of at least 0.96 to 1.04, preferably 0.98 to 1, for the end product, 02 and particularly preferably 0.99 to 1.01 is selected. Otherwise, the molecular weights in the end products are too low; then they are unusable. According to the teaching of the abovementioned US patent, thermoplastic polyurethanes which have been degraded thermally or by the action of water in the heat (hydrolysis) can also be used as the hydroxyl component, but this is to be regarded as difficult with regard to the mixing ratio because of their unknown, difficult to determine content of hydroxyl groups.

In addition, it is difficult to store the isocyanate component over a long period of time without changing the free isocyanate group content and thus also the molecular weight.

The above-mentioned recipe restrictions and the above-mentioned shortcomings of the prior art method call for an improvement.

The solution to this problem is a process for the two-component thermoplastic processing of polyurethanes and polyurethane ureas, which can be used much more universally and makes less precise dosing necessary.

It is particularly surprising not only that it was also possible to produce thermoplastic polyurethanes which are very easy to process outside the molecular weight limits of 100,000 to 200,000 and 30,000 to 150,000 mentioned in US Pat. No. 5,089,571, but also that these also have improved product properties, E.g.sp iel sw ei seb ei the f e sti gkeit, the solution, and the heat resistance.

The present invention relates to a process for producing thermoplastic polyurethanes by joint thermoplastic processing:

a) a polyurethane and / or polyurethane polyurea with free hydroxyl groups and / or amino groups and

b) a polyurethane and / or polyurethane polyurea, obtainable by the isocyanate polyaddition process with a key figure above 100,

characterized in that:

i) in the preparation of component b) a characteristic number of 110 to 150, preferably 110 to 135, is observed (excess isocyanate), and

ii) in the thermoplastic processing of components a) and b) the molar ratio of the calculated isocyanate excess of component b) to the content of free hydroxyl groups and / or amino groups of component a) of 1.02: 1 (mol of NCO: Mol OH or NH ₂ ) is up to 100: 1.

In a preferred embodiment, a molar ratio of the calculated isocyanate excess of component b) to the content of free hydroxyl groups and / or amino groups of at least 1.04: 1, very particularly preferably at least 1.05: 1, is maintained.

The thermoplastic processing of components a) and b) is preferably carried out by injection molding, extrusion or extrusion blow molding.

According to the invention, both fully reacted polyurethanes and non-thermoplastic polyurethanes can advantageously be used as raw materials for components a) and b) can be used. In addition, waste polyurethane material or production waste can also be used as raw materials.

Components a) and b) above are available from the following raw materials:

1) one or more, essentially linear polyols with molecular weights between 400 and 10,000,

2) one or more organic polyisocyanates and

3) a chain extender having isocyanate-reactive groups and having a molecular weight of 18 to 399, and optionally

4) auxiliaries and additives in a manner known per se.

1. According to the invention, essentially linear polyols with molecular weights between 400 and 10,000, preferably between 450 and 6,000, come in practically all known, preferably 3, optionally 3, in subordinate amounts - including more cerewitin-inactive groups (essentially hydroxyl groups ) containing polyester, polylactones, polyethers,

Polythioethers, polyesteramides, polycarbonates, polyacetals, vinyl polymers such as, for example, polybutadiene oils, polyhydroxyl compounds already containing urethane or urea groups, optionally modified natural polyols, and also other cerewitin-inactive groups such as compounds containing amino, carboxyl or thiol groups. These compounds correspond to the prior art and are described, for example, in DE-OS 23 02 564, 24 23 764 and 25 49 372 (US Pat. No. 3,963,679) and 24 02 840 (US Pat. No. 3,984,607) and in DE AS 24 57 387 (U.S. Patent 4,035,213) is described in detail. Preferred according to the invention are hydroxyl-containing polyesters of glycols and adipic acid, phthalic and / or terephthalic acid and also hydrogenation products, hydroxyl polycarbonates, polycaprolactones, - 5th

Polyethylene oxide, polypropylene oxide, polytetrahydrofuran and mixed polyether from ethylene oxide and propylene oxide and / or tetrahydrofuran.

Polyisocyanates to be used according to the invention are aliphatic, cycloaliphatic, araliphatic, aromatic and heterocyclic polyisocyanates, such as those e.g. by W. Siefken in Justus Liebigs Annalen der Chemie, 562, pages 75 to 136, for example those of the formula

Q (NCO) _n

in the

n 2 to 4, preferably 2, and

Q is an aliphatic hydrocarbon residue of 2 to 18, preferably

6 to 10 carbon atoms, a cycloaliphatic hydrocarbon radical with 4 to 15, preferably 5 to 10, carbon atoms, an aromatic hydrocarbon radical with 6 to 15, preferably 6 to 13, carbon atoms or an araliphatic hydrocarbon radical with 8 to 15, preferably means 8 to 12 carbon atoms, for example such

Polyisocyanates as described in DE-OS 28 32 253, pages 10 to 11. Q can also contain heteroatoms.

The technically easily accessible diisocyanates, e.g. 2,4- and 2,6-tolylene diisocyanate and any mixtures of these isomers ("TDI"), dicyclohexylmethane diisocyanate and 4,4 '

Diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate and any mixtures of these isomers and carbodiimide groups, urethane groups, allophanate groups or diisocyanate ("modified diisocyanates") containing urea groups, in particular those modified diisocyanates which differ from 2,4- and / or 2,6-tolylene diisocyanate or from 4,4'- and / or

Derive 2,4'-diphenylmethane diisocyanate. The functionality of the isocyanate should be at least 1.8. 3. Chain extenders having groups which are reactive toward isocyanates are compounds of molecular weight 18 to 399 with a functionality of at least 1.8. Possible reactive groups are: hydroxyl, amino, carboxyl and thiol groups. Examples include difunctional low molecular weight compounds such as

Dialcohols, diamines, amino alcohols, ether and ester alcohols and dicarboxylic acids such as e.g. Ethylene glycol, 1,4-butanediol and diethyltoluenediamine or its isomer mixture, but also water.

4. Possible auxiliaries and additives to be used are: the known fillers, reinforcing materials, antistatic agents,

Anti-aging agents, flame retardants, dyes and pigments, plasticizers, thermoplastics, inert solvents, lubricants and other processing aids, release agents, catalysts, each of an inorganic and / or organic nature, as they correspond to the prior art.

Implementation of the method according to the invention

Components a) and b) for thermoplastic processing are produced in accordance with the methods of the prior art which are known per se, but in b) while maintaining the characteristic number of at least 110 in accordance with feature i).

It is not important that the selected NCO excess is present in the product in whole or in part in the form of NCO groups, but it can e.g. also reacted to allophanate and / or biuret. As a result, the products to be processed according to the invention are largely independent of the storage. As with other polyurethanes, prolonged moisture storage of products a) and b) in the heat is not recommended.

Instead of the fully reacted components a) and b), mixtures of linear polyols 1), isocyanates 2) and chain extenders 3) and auxiliaries and additives 4) can also be used for the process according to the invention. The products can also contain monofunctional compounds, which are often referred to as chain terminators.

Individual components (polyols 1), isocyanates 2) and chain extenders 3)) can also have a functionality which is well below 1.8. This is particularly advantageous if other raw materials have a higher functionality, e.g. Have 6.

The raw materials mentioned can be used for the construction of component a) to be used according to the invention with free hydroxyl groups and also for the construction of component b) produced with an excess of NCO. Components a) and b) can be constructed from the same or different raw materials.

Components a) and b) to be used according to the invention are produced by processes known per se, such as e.g. produced in a screw reactor. In a particular embodiment, it is also possible to react fully reacted polyurethanes in the melt with alcohols, alkanolamines, diamines, dicarboxylic acids, isocyanates, preferably diisocyanates. This leads to a reduction in molecular weight. This degradation process has the advantage over the degradation process described in US Pat. No. 5,089,571 that the molecular weight and functionality of the products to be used (in the process according to the invention) can be set in a targeted manner and easily determined if required.

It is an advantage of the method according to the invention that an exact determination of the analytical data of components a) and b) is not necessary, since the mixing ratio of a) with b), in contrast to the method described in US Pat. No. 5,089,571 in one very large range is variable (feature ii).

The degradation process described for the production of components a) and b) according to the invention also enables the reuse of non-thermoplastic, for example crosslinked, polyurethane waste, such as, for example, flexible foam or elastomers. These can also just like polyurethane thermoplastics before Use for the production of components a) and / or b) have been in use for a long time (old material) or represent production waste.

It is also possible to selectively set a specific hardness of the process products according to the invention by using components a) and b) of different Shore hardness. This is also a consequence of the recipe insensitivity already mentioned.

For some processing techniques, such as extrusion, it is advantageous to achieve homogeneous process products if components a) and b) have approximately the same melt viscosities at the processing temperature. This can be achieved if e.g. the harder component a) with a large NCO deficit e.g. NCO: OH ratio of molar 0.8: 1 is produced. The method according to the invention also enables the reprocessing of polyurethanes and polyurethane ureas which have already been damaged by aging to give new products with good physical properties and good aging resistance.

The processing of the two-component polyurethane mixture according to the invention can be carried out in conventional melt processing machines, such as injection molding machines, extruders, in blow molding plants, presses, by a sintering process or powder spraying process. Of course, processing in solution, dispersion or emulsion is also possible in some cases. Components a) and b) can also have very different melting ranges, so that e.g. one component is dispersed or suspended in the other during shaping and is only melted and reacted by a later heat shock.

The process products are suitable for the production of solid and foamed moldings, coatings, foils, bonds.

The following examples illustrate the invention without, however, restricting it. Unless otherwise noted, quantities are to be understood as parts by weight or percentages by weight. Examples •

Comparative Example 1

a) Hydroxyl polyurethane

In the mixture of 100 parts by weight of a polybutanediol adipate with an average molecular weight of 2200 and 9.5 parts by weight of butanediol (1,4), 1 part by weight of ethylene diamine bisstearoylamide is uniformly distributed at 130 ° C. with exclusion of moisture. The melt is cooled to 80.degree. C. and 35.8 parts by weight of 4,4'-diphenylmethane diisocyanate heated to 60.degree. C. are homogeneously stirred in an open can, then it is poured into a bowl made of polytetrafluoroethylene, at 110.degree. C. for 1 hour and over

Maintained at 80 ° C overnight and granulated after cooling. In the product (1A) thus produced, the NCO: OH ratio is 0.95.

b) isocyanate polyurethane

The procedure is as described in Example la), but 39.7 parts by weight of 4,4'-diphenylmethane diisocyanate are used, so that a product

(1B) with an NCO: OH ratio of 1.05. Equal parts by weight of granules of products (1 A) and (1B) are mixed homogeneously and processed in an Anker V14 injection molding machine to form test specimens (IC) which are stored at 80 ° C for 16 hours; Table 1 shows the measured values determined.

Example 2

The procedure is as described in Example la), but 41.6 parts by weight of 4,4'-diphenylmethane diisocyanate are used and a product (2) with an NCO: OH ratio of 1.10 is obtained. 9 parts by weight of polyurethane (2) are mixed with 1 part by weight of polyurethane (1A) as granules and sprayed together in the injection molding machine. The molded parts (2A) have a calculated NCOOH ratio of 1.085 and are stored at 80 ° C. for 16 hours. The results of the physical tests are summarized in Table 1. - 10 -

Example 3

The procedure is as described in Example 2, but 45.3 parts by weight of 4,4'-diphenylmethane diisocyanate are used. The product (3) obtained has an NCOOH ratio of 1.20 and is mixed with product Ia in the weight ratio 1: 1 and 9: 1 (= excess product (3)) in the injection molding machine to give products (3A) NCO : OH ratio (calculated) 1.075 and (3B) NCO.OH (calculated) 1.175 processed (result see table 1).

Table 1

Test standard (IC) (2A) (3A) (3B)

Elasticity (%) DIN 53 512 46 42 42 39

Tear resistance (MPa) DIN 53 504 30 37 34 37

Elongation at break (5) DIN 53 504 432 542 473 512

Shore hardness A DIN 53 505 86 84 85 85

Compression set DIN 53 517 55 35 38 25 (24 h 70 ° C,%)

It can be seen from Table 1 that the products according to the invention are superior in their tensile strength, elongation at break and heat resistance, comparable to polyurethane (IC) produced according to the teaching of US Pat. No. 5,089,571.

Example 4

Waste of a polyurethane obtained by reaction casting consisting of 100 parts by weight of polyethanediol adipate with an average molecular weight of 2000, 4.5 parts by weight of butanediol (1,4), 0.3 part by weight of trimethylolpropane and 24 parts by weight of naphthylene ( 1,5) -diisocyanate are reacted in a twin-screw reactor with 0.82 part by weight of butanediol- (1,4) per 100 parts waste at about 230 ° C. - 1 1 -

(Polyurethane (4)). The product is processed into test specimens in an injection molding machine. For physical values see table 2.

Example 5

Approximately 3 months old production waste of a polyurethane obtained by the two-component casting process from 100 parts by weight of polyethanediol butanediol adipate with an average molecular weight of 2000, 5.9 parts by weight of butanediol (1,4) and 27 parts by weight of naphthylene (1,4 5) -diisocyanate (NCO: OH ratio = 1.11) are granulated (product (5)) and mixed in a ratio of 2 parts by weight of polyurethane (5) to 1 part by weight of polyurethane (4) and in an injection molding machine form sprayed with release agent into test specimens at about 220 ° C (product 5A). For product properties, see table 2.

Example 6

The procedure is as described in Example 4, but 2.2 parts by weight of butanediol- (1.4) are used for polyurethane (6A) and 14.1 parts by weight instead of 1,4-butanediol for product (6B) 4,4'-diphenylmethane diisocyanate used. Product (6C) is obtained by mixing and later injection molding (processing temperature 220 ° C. max.) Equal parts by weight of granules of the polyurethanes (6A) and (6B). The physical properties are summarized in Table 2. Storage of the granulate mixture for 5 months leads to spray bodies with practically the same properties.

Table 2 Properties of the products from Examples 4, 5 and 6

product

Test standard (4) (5A) (6C)

Elasticity (%) DIN 53 512 38 40 40

Tensile strength (MPa) DIN 53 504 10 21 32

Elongation at break (%) DIN 53 504 250 420 535

Shore hardness A DIN 53 505 85 87 85 Example 7

From 100 parts by weight of a hexanediol-neopentyl glycol polyadipate with an average molecular weight of approx. 2200, 25 parts by weight of butanediol (1,4), 0.5 parts by weight of ethylene bisstearoylamide and 65, 45 parts by weight of 4,4 '-Diphenylmethane diisocyanate is a thermoplastic polyurethane (7) with a Shore D hardness of 52. The NCO: OH ratio is 0.81 (molecular weight Mn = 3120). 68 parts by weight of the granules of product (7) are mixed with 58 parts by weight of product (3) and processed to test specimens (7A) by injection molding. For physical properties, see Table 3.

Table 3 Physical properties of product (7A)

Test standard product (7A)

Rebound resilience (%) DIN 53 512 43

Tensile strength (MPa) DIN 53 504 28

Elongation at break (%) DIN 53 504 539

Module 100% (MPa) DIN 53 504 9.7

Module 300% (MPa) DIN 53 504 13.8

Shore hardness A DIN 53 505 92

The results summarized in Table 3 show that it is also possible according to the process according to the invention to mix a component with free NCO- or zerewitinoffactive groups with another component with higher or lower hardness reacting with this and to process this mixture and so on selectively - within certain limits - to set a desired hardness of the end product. The NCO.Zerewitinoff active group ratio is insignificant as long as this is not significantly less than 1.00 in the end product. Example 8

A thermoplastic polyurethane is produced as described in Comparative Example 1. In contrast to Comparative Example 1, 38.6 parts by weight of 4,4'-diphenylmethane diisocyanate are used, which corresponds to an NCO: OH ratio of 1.02. Injection molded articles are produced from the granules (product 8A) and are stored in water at 80 ° C. for 14 days. After drying in air and then in a vacuum desiccator, the injection molded articles have a tensile strength of about 5 MPa as a result of the hydrolytic action. The dried spray bodies are granulated.

12 parts by weight of 1,6-hexanediol are heated to 200 ° C. under nitrogen in a three-necked flask equipped with a stirrer and reflux condenser in the presence of 50 ppm of titanium tetrabutylate. 100 parts by weight of the granules obtained from the dried, hydrolysis-aged spray bodies are added in portions so that the contents of the flask remain stirrable. The temperature is slowly raised to 220 ° C. As soon as a homogeneous melt has formed, the mixture is cooled to 180 ° C., poured into a flat Teflon dish and the melt is allowed to solidify and comminute (product (8B)).

100 parts by weight of the product (8B) are mixed with 488.5 parts by weight of the product (3) as granules, the NCO: OH ratio of the mixture is about 1.05 (theoretically), and in one Injection molding machine processed into test specimens (product (8C) (results see table 4).

Table 4 Physical properties of product (8C)

Test standard product (8C)

Tensile strength (MPa) DIN 53 504 36

Elongation at break (%) DIN 53 504 484 As can be seen from Table 4, the process according to the invention is suitable for reusing hydrolytically degraded polyester polyurethanes in practically new thermoplastics.

Example 9

The mixture of 100 parts by weight of polybutanediol adipate with an average molecular weight of 2000, 8.08 parts by weight of butanediol- (1,4), 2.82 parts by weight of diethyltoluenediamine (isomer mixture 2,6-isomer: 2, 4-isomer = approx. 35:65) and 2 parts by weight of ethylene bisstearoylamide is heated to 170 ° C. 36.7 parts by weight of 4,4'-diisocyanatodiphenylmethane (corresponding to an NCO: OH ratio of 0.94) are stirred in rapidly and poured into a flat dish made of polytetrafluoroethylene, 1 hour at 110 ° C. and 16 hours at 80 ° C stored and granulated (product (9)).

Example 10

The procedure is as described in Example 9, but 46.8 parts by weight of 4,4'-diisocyanatodiphenylmethane are used and product (10) (NCO: OH = 1.20) is obtained. The granules of products (9) and (10) are mixed in a weight ratio of 2: 3 and processed into test specimens by injection molding (10A).

Table 5 Physical properties of the product (10A)

Unit test standard product (10A)

Module at 100% elongation MPa DIN 53 504 6

Module at 300% elongation MPa DIN 53 504 20.1

Tensile strength MPa DIN 53 504 54

Elongation at break% DIN 53 504 498

Shore hardness A DIN 53 505 84

Rebound elasticity% DIN 53 512 37 Example 11

1655 parts by weight of a propylene-ethylene oxide mixed polyether started on glycerol with the OH number 56 and polypropylene oxide started on trimethylolpropane with the OH number 56 are in 140 parts by weight of hexanediol (1.6) at 230 ° C. (Polyether ratio 100: 3.5) and tolylene diisocyanate (proportion of the 2,4-isomer 80%, remainder: 2,6-isomer) as main components of the standard hot-molded foam produced are stirred under nitrogen until a homogeneous solution is obtained. Polyurethane (11) with a theoretical OH number of 74 is formed.

Example 12A

The product (11) is mixed with product (3) so that there is a theoretical NCO: OH ratio of 1.00. This mixture (12A) is sprayed off in an injection molding machine to give test specimens which have a tensile strength of 15.5 MPa and an elongation at break of 435% with a hardness of 78 Shore A.

Example 12B

The procedure is as described in Example 12A, but components (3) and (11) are mixed in such a way that a theoretical NCO: OH ratio of 1.05 results. The injection molded bodies (12B) have a tensile strength of 18.6 MPa.

Example 13A

The procedure is as described in Examples 1 to 3, but an NCO: OH ratio of 0.97 is selected. After tempering overnight at 80 ° C. at room temperature, the product (13A) gives 20% by weight dissolved in a mixture of dimethylacetamide and methyl ethyl ketone in a ratio of 4: 1, at room temperature a solution viscosity of 660 mPa.s. The melting temperature range of the tempered polyurethane is 195 ° C. Example 13B

The procedure is as described in Example 13A, but an NCOOH ratio of 1.01 is chosen and, under the same conditions, a solution viscosity of 79,000 mPa.s is measured for the product (13B).

Example 13C

The procedure is as described in Example 13A, but an NCOOH ratio of 1.30 is chosen. The product (13C) melts at about 214 ° C. It is not soluble in the solvent mixture mentioned in Example 13 A under the conditions mentioned but only swells.

Example 13D

The granules from Examples 13 A and C are mixed in a weight ratio of 1: 2.3, so that there is a theoretical NCO: OH ratio of 1.2, and then sprayed into test specimens which are stored at 80 ° C. overnight (Product (13D)). The test specimens are not soluble in the solvent mixture mentioned in Example 13 A and have a tensile strength of 27.8 MPa.

It can be seen from Examples 13 A to D that crosslinked products can also be processed by the process according to the invention.

Comparative Example 14A

The procedure is analogous to Example 3A in US Pat. No. 5,089,571 and 100 parts by weight of polytetrahydrofuran with an average molecular weight of 1000, 20.7 parts by weight of butanediol- (1,4), 0.12 part by weight of ethylene bisstearoylamide (as commercially available release agent), 0.12 part by weight of a commercially available antioxidant in the presence of 0.01 part by weight of tin (II) octoate with 78.4 parts by weight of 4,4'-diphenylmethane diisocyanate. The molar NCO: OH ratio, as described in the example of US Pat. No. 5,089,571, is 0.95 (product (14A)). Comparative Example 14B

The procedure is as described in Example 14A, but an NCO: OH ratio of 1.06 is selected as in Example 3B of US Pat. No. 5,089,571 (product (14B)).

Comparative Example 14C

The products (14A) and (14B) are mixed in a weight ratio of 4: 1 (this corresponds to the ratio claimed in US Pat. No. 5,089,571 as claimed in the invention, as in Claims 1, 3 and 4) and this mixture in an injection molding ¬ machine processed into test specimens (product (14C)). The mechanical values are summarized in Table 6.

Example 15

The procedure is as described in Comparative Example 14A, but an NCO: OH ratio of 1.12 is selected (product 15). Products (15) and (14A) are mixed in a weight ratio of 1: 4 and this mixture is processed by injection molding (product 15A). In another mixture, these two polyurethanes (15) and (14A) are hosed down in a weight ratio of 2: 1 (product 15B), for mechanical values see table 6.

Table 6 Physical properties of products (14C), (15A) and (15B)

Unit (14C) (15A) (15B)

Modulus at 100% elongation MPa 11.9 11.0 11.7

Modulus at 300% elongation MPa - 18.9 16.1

Tensile strength MPa 12.0 24.3 20.3

Elongation at break% 126 398 404

Rebound 1 elasticity% 35.8 36.8 38.7 From Table 6 it can be seen that the products (15A) and (15B) corresponding to this invention are clearly superior in strength to the product (14C) according to claims 1, 3 and 4 of US Pat. No. 5,089,571.

Claims

claims

1. A process for producing thermoplastic polyurethanes by joint thermoplastic processing:

characterized in that:

i) in the production of component b) a key figure from 110 to

150 is observed (excess isocyanate) and

ii) in the thermoplastic processing of components a) and b) the molar ratio of the calculated isocyanate excess

Component b) to the content of free hydroxyl groups and / or amino groups of component a) in the range of 1.02: 1 (mol

NCO: mol OH or NH ₂ ) is up to 100: 1.

2. The method according to claim 1, characterized in that the molar ratio of the excess isocyanate of component b) to the content of free hydroxyl groups and / or amino groups of component a) is at least 1.04: 1.

3. The method according to claim 1, characterized in that the molar ratio of the isocyanate excess of component b) to the content of free hydroxyl groups and / or amino groups of component a) is at least 1.05: 1.

4. Process according to claims 1 to 3, characterized in that the thermoplastic processing of components a) and b) is carried out by injection molding, extrusion or extinction blow molding.

5. The method according to claims 1 to 4, characterized in that for the production of components a) and / or b) fully reacted polyurethane is used as raw material.

6. The method according to claim 5, characterized in that the polyurethane used as a raw material is not a thermoplastic polyurethane.

7. The method according to claims 5 and 6, characterized in that the polyurethane used as raw material is a polyurethane waste material and / or

-production waste.

8. The method according to claim 7, characterized in that the polyurethanes A) and B) to be used according to the invention have different hardnesses.