EP2566905A1

EP2566905A1 - Polyurethane elastomers, a method for producing same, and use thereof

Info

Publication number: EP2566905A1
Application number: EP11717624A
Authority: EP
Inventors: Jens Krause; Manfred Schmidt
Original assignee: Bayer Intellectual Property GmbH
Current assignee: Bayer Intellectual Property GmbH
Priority date: 2010-05-07
Filing date: 2011-05-02
Publication date: 2013-03-13
Also published as: CN102933631A; JP2013525583A; MX2012012904A; ZA201209249B; KR20130103337A; WO2011138275A1; RU2012152518A; US20130109830A1

Abstract

The invention relates to cellular and non-cellular polyurethane (PUR) elastomers made of NCO functional prepolymers based on polyisocyanates having portions of non-monomers, to a method for producing same, and to the use thereof.

Description

Polyurethane elastomers, a process for their preparation and their use

The present invention relates to cellular and non-cellular polyurethane (PUR) elastomers of NCO-functional prepolymers based on polyisocyanates with proportions of trimers, a process for their preparation and their use.

Polyurethane elastomers are used in numerous wear-prone applications. In addition to wear due to, for example, abrasion and / or lack of tear propagation resistance, in dynamic applications, e.g. Rollers, wheels, gaskets, cellular buffer elements and cellular shoe soles, wear due to deformation and / or heat build-up after a certain number of repeated loads. These loads usually occur periodically. This leads to high permanent deformations, which make further use impossible. Also, the internal heat build-up (by non-elastic interactions) may be so high that the polyurethane heats up to burst under stress. It is also known that by increasing the functionality of the polyol above 2, the dynamic resistance increases, but at the same time the tear values decrease so much that the elastomer is destroyed by non-dynamic wear phenomena.

The object of the invention was therefore to provide an elastomer available which has a low functionality and at the same time shows a very good tear strength and a very good dynamic behavior.

Surprisingly, it has now been found that the mechanical properties (eg abrasion, tear stress, tear propagation resistance, elongation at break) of polyurethanes are produced by using special NCO prepolymers based on polyisocyanates specified below without changing the mechanical-physical properties with simultaneously improved dynamic properties can.

The invention relates to a process for the preparation of polyurethane elastomers, which is characterized in that a) monomeric polyisocyanate is reacted by means of a trimerization catalyst in an amount of 0, 1 to 2000 ppm, based on monomeric polyisocyanate, wherein the reaction with the trimerization catalyst at a content of 0.01 to 5.0 wt .-% of reacted polyisocyanate, based on the total polyisocyanate, by means of a stopper, which is used in a molar ratio of stopper to trimerization catalyst of 1: 2 to 20: 1 is stopped . b) the mixture of monomeric and reacted polyisocyanate from a) is reacted with polyols having OH numbers of 20 to 200 mg KOH / g and functionalities of 1.95 to 2.40 to give an NCO-terminated prepolymer, c) the NCO- terminated prepolymer is reacted with chain extenders and / or crosslinkers to polyurethane elastomer, wherein the monomeric polyisocyanate and / or the polyols may optionally contain auxiliaries and / or additives.

Another object of the invention is a process for the preparation of NCO-terminated prepolymers, which is characterized in that a) monomeric polyisocyanate by means of a trimerization catalyst in an amount of

0, 1 to 2000 ppm, based on monomeric polyisocyanate, is reacted, wherein the reaction with the trimerization catalyst in a proportion of 0.01 to 5.0 wt .-% of reacted polyisocyanate, based on the total polyisocyanate, by means of a stopper, b) the mixture of monomeric and reacted polyisocyanate from a) with polyols having OH numbers of from 20 to 200 mg KOH / g and is stopped in a molar ratio of stopper to trimerization catalyst of 1: 2 to 20: 1 Functionalities of 1.95 to 2.40 is converted to an NCO-terminated prepolymer, wherein the monomeric polyisocyanate and / or the polyols may optionally contain auxiliaries and / or additives.

Another object of the invention is a process for the preparation of mixtures of monomeric and non-monomeric polyisocyanates, which is characterized in that a) monomeric polyisocyanate by means of a trimerization catalyst in an amount of 0, 1 to 2000 ppm, based on monomeric polyisocyanate, is reacted wherein the reaction with the trimerization catalyst at a proportion of 0.01 to 5.0 wt .-% of reacted polyisocyanate, based on the total polyisocyanate, by means of a stopper, in a molar ratio of stopper to Trimerisierungskatalysator of 1: 2 to 20: 1 is used is stopped, wherein the monomeric polyisocyanate may optionally contain auxiliaries and / or additives.

The invention also polyurethane elastomers, which are available from a) a mixture of monomeric and non-monomeric polyisocyanate in a proportion of 0.01 to 5.0 wt .-% of non-monomeric polyisocyanate, based on the total polyisocyanate, wherein the mixture is obtainable from monomeric polyisocyanate by means of a trimerization catalyst in an amount from 0, 1 to 2000 ppm, based on monomeric polyisocyanate, and by means of a stopper in a molar ratio of stopper to trimerization catalyst of 1: 2 to 20: 1, b) polyols having OH numbers of 20 to 200 mg KOH / g and Functionalities of 1.95 to 2.40 and c) chain extenders and / or crosslinkers, d) optionally in the presence of auxiliaries and / or additives.

Another object of the invention are NCO-terminated prepolymers, which are obtainable from a) a mixture of monomeric and non-monomeric polyisocyanate in a proportion of 0.01 to 5.0 wt .-% of non-monomeric polyisocyanate, based on the total polyisocyanate wherein the mixture is obtainable from monomeric polyisocyanate by means of a trimerization catalyst in an amount of 0, 1 to 2000 ppm, based on monomeric polyisocyanate, and by means of a stopper in a molar ratio of stopper to trimerization catalyst from 1: 2 to 20: 1, and b) polyols having OH numbers of 20 to 200 mg KOH / g and functionalities of 1.95 to 2.40, d) optionally in the presence of auxiliaries and / or additives.

Another object of the invention are mixtures of monomeric and non-monomeric polyisocyanate in a proportion of 0.01 to 5.0 wt .-% of non-monomeric polyisocyanate, based on the total polyisocyanate, obtainable from a) monomeric polyisocyanate by means of a trimerization catalyst in one Amount of 0.1 to 2000 ppm, based on monomeric polyisocyanate, and by means of a stopper in a molar ratio of stopper to trimerization catalyst of 1: 2 to 20: 1.

The reaction is carried out by means of customary trimerization catalysts, as described in Houben-Weyl, Methods of Organic Chemistry, Volume E20, Part 2, Georg Thieme Verlag, Stuttgart, 1987, pp. 1739-1751, such as quaternary ammonium hydroxides, benzyldimethyl amine, triethylamine, Mannich bases of phenols or mixtures of these catalysts. Preferably, phenol Mannich bases are used, which can be obtained by reacting phenol or bisphenol A with dimethylamine and formaldehyde. The trimerization catalyst can be dissolved in a solvent such as toluene, ethyl acetate, alcohol (eg, methanol, ethanol and 2-ethyl-1-hexanol), ethers or polyethers, phosphoric acid esters such as tris (2-chloroisopropyl) phosphate (TCPP) or Triethyl phosphate (TEP) are present.

After the desired reaction, the reaction is stopped, preferably with Broenstedt or Lewis acids, such as hydrochloric acid, benzoyl chloride or organomercinic acids, e.g. Dibutyl phosphate.

The polyurethane elastomers according to the invention have very good dynamic properties combined with good mechanical-physical properties.

The polyurethane elastomers according to the invention are preferably used as cast elastomers for the production of, for example, rollers, wheels and conveyor belts.

Preferably, the polyurethane elastomer parts are produced by the casting process. Here, the NCO-terminated prepolymers are first prepared. The NCO-terminated prepolymers are reacted either directly after their preparation with a chain extender / crosslinker, or they are cooled to low temperatures (storage temperature) for the purpose of subsequent chain extension / V ernetzung and stored.

It is particularly favorable in the synthesis via NCO-terminated prepolymers that part of the heat of reaction is already produced in the synthesis of the NCO-terminated prepolymer and that thereby the exotherm in the actual polymer structure to the elastomer precipitates smaller. This has a favorable effect on the speed of the molecular weight build-up and allows longer casting times, thus represents a processing advantage.

In a particularly preferred embodiment, the NCO-terminated prepolymers are first degassed by applying a reduced pressure at room temperature or at elevated temperature and then reacted - usually at elevated temperature - with the chain extender / V ernetzer.

In the process of the invention, the NCO-terminated prepolymer is preferably heated to a temperature of 60 ° C to 110 ° C and degassed with stirring under vacuum. Thereafter, the chain extender and / or crosslinker is added in liquid form, which is optionally heated to temperatures of typically at least 5 ° C above its melting point. This reaction mixture is preferably poured into preheated molds (preferably 90 ° C to 120 ° C) and held at 90 ° C to 140 ° C for about 24 hours. The NCO-functional prepolymers are preferably prepared from the following polyisocyanates: NDI (1,5-naphthalene diisocyanate), TDI (2,4- and 2,6-toluene diisocyanate or mixtures thereof), MDI (2,2'-, 2,4 ') and 4,4'-MDI or mixtures thereof), TODI (3,3'-dimethyl-4,4'-biphenyl diisocyanate), PPDI (1, 4-paraphenylene diisocyanate) and CHDI (cyclohexyl diisocyanate) and mixtures of the polyisocyanates and / or modified compounds of the polyisocyanates, such as uretonimines, polymers of isocyanates (polymeric MDI, such as Desmodur ^® 44V20L from Bayer MaterialScience AG) or other modified isocyanates. Alternatively, but less preferably, aliphatic isocyanates such as isophorone diisocyanate, ring-hydrogenated MDI (Desmodur ^® W), and hexamethylene diisocyanate and derivatives of these isocyanates may be used or added.

In a specific embodiment, the NCO-functional prepolymers are prepared with an excess of isocyanate. In a further step, the free isocyanate is removed, so that the content of free isocyanate is reduced to <1% by weight, preferably to <0.1% by weight. The removal is usually carried out in vacuo (for example by thin layers of short and / or falling film evaporator). Optionally, this entrainment agents can be used. This can e.g. a solvent or gas, e.g. Be nitrogen.

These NCO prepolymers thus obtained may be blended, and as zweikom- ponentiges system, for example, with blocked amines, such as diaminodiphenylmethane blocked (eg Caytur ^® 31) (partially in the literature also referred to as component system) verwen- be det.

As polyols, it is possible to use, for example, polyether, polyester, polycarbonate and polyetherester polyols having hydroxyl numbers (OH numbers) of 20 to 200 mg KOH / g, preferably 27 to 150, particularly preferably 27 to 120.

Polyether polyols are prepared either by alkaline catalysis or by Doppelmetallcyanid- catalysis or optionally in stepwise reaction by alkaline catalysis and Doppelmetallcyamdkatalyse of a starter molecule and epoxides, preferably ethylene and / or propylene oxide and have terminal hydroxyl groups. Suitable starters are the compounds with hydroxyl and / or amino groups known to those skilled in the art, as well as water. The functionality of the starter is at least 2 and at most 4. Of course, mixtures of multiple starters can be used. Furthermore, mixtures of several polyether polyols can be used as polyether polyols. Alternatively, preference is given to using polyether polyols based on C p, for example polytetrahydrofuran become. Furthermore, it is also possible to use so-called C3-polyols based on 1,3-propylene glycol.

Polyester polyols are prepared in a conventional manner by polycondensation of alipahtic and / or aromatic polycarboxylic acids having 4 to 16 carbon atoms, optionally from their anhydrides and optionally from their low molecular weight esters, including ring esters, being used as the reaction component predominantly low molecular weight polyols having 2 to 12 carbon atoms come. The functionality of the synthesis components for polyester polyols is preferably 2, but in individual cases may be greater than 2, wherein the components are used with functionalities greater than 2 only in small amounts, so that the arithmetic number average functionality of polyester polyols in the range of 2 to 2.5, preferably 2 to 2.1.

Polyetheresterpolyole be prepared for example by concomitant use of polyether polyols in the Polyesterpolyolsynthese.

Polycarbonate polyols are prepared according to the prior art e.g. from carbonic acid derivatives, e.g. Dimethyl or diphenyl carbonate or phosgene and polyols obtained by polycondensation.

As chain extenders and / or crosslinkers, e.g. aromatic aminic substances, e.g. Diethyltoluenediamine (DETDA), 3,3'-dichloro-4,4'-diaminodiphenylmethane (MBOCA), 3,5-diamino-4-chloro-isobutylbenzoate, 4-methyl-2,6-bis (methylthio) -l , 3-diaminobenzene (Ethacure 300), trimethylene glycol di-p-aminobenzoate (Polacure 740M) and 4,4'-diamino-2,2'-dichloro-5,5'-diethyldiphenylmethane (MCDEA) and 4,4 '- Diamino-diphenylmethane (MDA) or salt-blocked MDA (Caytur 21, 31, etc. from Chemtura) can be used. Aliphatic aminic chain extenders and / or crosslinkers may also be used or co-used. Likewise, chain extenders and / or crosslinkers from the group of polyols, such as 1,2-ethanediol, 1, 2-propanediol, 1, 3-propanediol, 1, 4-butanediol, glycerol, trimethylolpropane and mixtures thereof can be used. Particular preference is given to using 1,4-butanediol as chain extender.

Furthermore, auxiliaries and additives, such as catalysts, stabilizers, UV protectants, hydrolysis protectants, emulsifiers, preferably incorporable dyes and color pigments, cell regulators and fillers can be used. Examples of catalysts are trialkylamines, diazabicyclooctane, tin dioctoate, dibutyltin dilaurate, N-alkylmorpholine, lead, zinc, calcium, magnesium octoate, the corresponding naphthenates and p-nitrophenolate. Examples of stabilizers are Broenstedt and Lewis acids, such as hydrochloric acid, benzoyl chloride, Organomineralsäuren, for example, dibutyl phosphate, adipic acid, malic acid, succinic acid, racemic acid or citric acid.

Examples of UV protectants and hydrolysis protectants are 2,6-dibutyl-4-methylphenol and sterically hindered carbodiimides.

Incorporatable dyes are those which have Zerewitinoff-active hydrogen atoms, so can react with NCO groups.

An overview is provided in G. Oertel, Polyurethane Handbook, ^2nd edition, Carl Hanser Verlag, Munich, 1994, ch. 3.4., Included. The polyurethane elastomers prepared according to the invention are preferred for the production of cast elastomers such as rollers, wheels, rollers, hydrocyclones, sieves, pigs and cellular and non-cellular elastomers for buffer elements.

The invention will be explained in more detail with reference to the following examples.

Examples

Used connections:

Catalyst: Accelerator 960-1 from Huntsman (2,4,6-tris (dimethylaminomethyl) phenol)

MDI Desmodur ^® 44M from Bayer MaterialScience AG (monomeric 4,4'-diphenylmethane diisocyanate); NCO content: 33.6% by weight

Polyester: molecular weight ethylene butylene adipates Mono 2000 g / mol based on, Desmophen ^® 2001 KS from Bayer MaterialScience AG

Stopper: benzoyl chloride

BDO: 1,4-butanediol prepolymer 1 (according to the invention):

The MDI was initially introduced at 60 ° C., admixed with 200 ppm based on MDI, catalyst and stirred for 1 hour 30 minutes. Thereafter, the reaction was treated with a 1.5 molar excess of stoppers. The NCO content was determined to be 32.9% by weight. 34.218 parts by weight of this mixture were added at 60 ° C with 65.682 parts by weight of polyester polyol at 60 ° C and reacted with stirring for 3 hours at 80 ° C with each other. The NCO content of the prepolymer was determined to be 8.42% by weight. The prepolymer contained undissolved particles and could be processed by hand into an elastomer.

Prepolymer 2 (according to the invention):

A portion of prepolymer 1 was removed and filtered so that undissolved particles are no longer present. Particles may be annoying when machined. The NCO content was determined to be 8.40% by weight.

Prepolymer 3 (according to the invention):

The MDI was initially charged at 60 ° C., admixed with 50 ppm, based on MDI, catalyst, and stirred for 1 hour 30 minutes. Thereafter, the reaction was treated with a 1.5 molar excess of stoppers. The NCO content was determined to be 33.5% by weight. 33.72 parts by wt. MDI were added at 60 ° C with 66.28 wt. Parts Polyesterpolyol at 60 ° C and reacted with stirring for 3 hours at 80 ° C with each other. The NCO content of the prepolymer was determined to be 8.50% by weight. The prepolymer contained no undissolved particles. Prepolymer 4 (not according to the invention):

33.61 parts by weight of MDI were added at 60 ° C with 66.39 parts by weight of polyester polyol at 60 ° C and reacted with stirring for 3 hours at 80 ° C with each other. The NCO content of the prepolymer was determined to be 8.37% by weight. The prepolymer contained no undissolved particles. Polyurethane elastomer:

In each case 100 parts by weight of prepolymer were reacted at 80 ° C with 1, 4-butanediol (amounts are given in Table 1) and poured into a hot mold at 120 ° C. The mechanical properties were measured after 7 days.

Table: Processing details and mechanical results of the respective polyurethane elastomers

Polyurethane elastomer: prepoly- prepolyPrepolyPrepolymer4 mer 1 mer 2 mer 3

comparison

NCO content [wt%] 8.37 8.42 8.4 8.5

1, 4-butanediol [parts by weight] 8,55 8,60 8,60 8,69

Pot life [sec] 225 300 300 240

Release time [min.] 45 70 70 45

mechanical

Properties:

Hardness at 20 ° C DIN 53505 Shore A 92 91 91 92

Hardness at -5 ° C DIN 53505 Shore A 95 95 95 95

Hardness at 80 ° C DIN 53505 Shore A 89 88 88 89

10% Modulus DIN 53504 [MPa] 3.3 3.2 3.4 3.4

100% Modulus DIN 53504 [MPa] 7.5 7.6 7.8 7.8

200% Modulus DIN 53504 [MPa] 10.5 1 1 10.8 1 1.1

300% Modulus DIN 53504 [MPa] 14.7 15.7 14.8 15.4

Tear stress DIN 53504 [MPa] 54 49 57 55

Elongation at break DIN 53504 [%] 557 515 570 562

Tear strength DIN 53515 [kN / m] 1 19 1 16 1 17 120

Tear strength

(scribed) DIN 53515 [kN / m] 65 63 72 66

Rebound resilience DIN 53512 [%] 47 42 45 45

Abrasion DIN 53516 [mm ³ ] 30 30 30 30

Compression set

24h / 70 ° C DIN 53517 [%] 18 17 17 18 It is clear from Table 1 that the mechanical properties do not change within the scope of the measurement accuracy due to the partial conversion.

Table 2: Dynamic results of the polyurethane elastomers Cylinders made of polyurethane elastomer with a diameter of 18 mm and a height of 25 mm were tested in each case. The cylinder was pulsed with a force of 1, 2 kN and a fixed frequency at an amplitude of 0.8 kN. The test was stopped at a deformation of 60%.

: Test was stopped after 16000 cycles. 60% deformation has not yet been achieved. From the test results, it becomes clear that a partial conversion increases the dynamic performance by a factor of 2-3 without adversely affecting the mechanical-physical properties or the processing. Even with a low conversion, elastomers with good mechanical-physical properties and very good dynamic properties are obtained, but without the formation of particles that may need to be filtered before being processed by machine.

The systems according to the invention have a unique combination of advantageous properties with respect to prepolymer viscosity, casting time, mechanical and mechanical-dynamic properties.

Claims

claims

1. A process for the preparation of polyurethane elastomers, characterized in that a) monomeric polyisocyanate by means of a trimerization catalyst in an amount of 0, 1 to 2000 ppm, based on monomeric polyisocyanate, is reacted, wherein the reaction at a level of 0.01 to 5 , 0 wt .-% of reacted polyisocyanate, based on the total polyisocyanate, by means of a stopper, which is used in a molar ratio of stopper to trimerization catalyst from 1: 2 to 20: 1 is stopped, b) the mixture of monomeric and reacted polyisocyanate from a) with polyols having OH numbers of 20 to 200 mg KOH / g and functionalities of 1.95 to 2.40 to one

NCO-terminated prepolymer is reacted, c) the NCO-terminated prepolymer is reacted with chain extenders and / or crosslinkers to polyurethane elastomer, wherein the monomeric polyisocyanate and / or the polyols may optionally contain auxiliaries and / or additives.

2. A process for preparing NCO-terminated prepolymers, characterized in that a) monomeric polyisocyanate by means of a trimerization catalyst in an amount of 0, 1 to 2000 ppm, based on monomeric polyisocyanate, is reacted, wherein the reaction at a fraction of 0, 01 to 5.0 wt .-% of reacted polyisocyanate, based on the total polyisocyanate, by means of a stopper which in a molar

B) the mixture of monomeric and reacted polyisocyanate from a) with polyols having OH numbers of 20 to 200 mg KOH / g and functionalities of 1, b) the mixture of stopper to trimerization catalyst from 1: 2 to 20: 1 is used 95 to 2.40 to an NCO-terminated prepolymer is reacted, wherein the monomeric polyisocyanate and / or the polyols may optionally contain auxiliaries and / or additives.

3. A process for the preparation of mixtures of monomeric and non-monomeric polyisocyanate, characterized in that a) monomeric polyisocyanate by means of a trimerization catalyst in an amount of 0, 1 to 2000 ppm, based on monomeric polyisocyanate, is reacted, wherein the reaction at a level of 0.01 to 5.0 wt .-% of reacted polyisocyanate, based on the entire polyisocyanate, by means of a stopper, which is used in a molar ratio of stopper to trimerization catalyst from 1: 2 to 20: 1 is stopped, wherein the monomeric polyisocyanate may optionally contain auxiliaries and / or additives.

4. polyurethane elastomers obtainable from a) a mixture of monomeric and non-monomeric polyisocyanate in a proportion of 0.01 to 5.0 wt .-% of non-monomeric polyisocyanate, based on the total polyisocyanate, wherein the mixture is obtainable from monomeric polyisocyanate by means of a trimerization catalyst in an amount of 0, 1 to 2000 ppm, based on monomeric polyisocyanate, and by means of a stopper in a molar ratio of stopper to trimerization catalyst of 1: 2 to 20: 1, b) polyols having OH numbers of 20 to 200 mg KOH / g and functionalities from 1.95 to 2.40 and c) chain extenders and / or crosslinkers, d) optionally in the presence of auxiliaries and / or additives.

5. NCO-terminated prepolymers obtainable from a) a mixture of monomeric and non-monomeric polyisocyanate in a proportion of 0.01 to 5.0 wt .-% of non-monomeric polyisocyanate, based on the total polyisocyanate, wherein the mixture is obtainable from monomeric polyisocyanate by means of a trimerization catalyst in an amount of 0.1 to 2000 ppm, based on monomeric polyisocyanate, and by means of a stopper in a molar ratio of stopper to trimerization catalyst of 1: 2 to 20: 1, and b) polyols with OH Numbers from 20 to 200 mg KOH / g and functionalities from 1.95 to 2.40, d) optionally in the presence of auxiliaries and / or additives.

6. Mixtures of monomeric and non-monomeric polyisocyanate in a proportion of 0.01 to 5.0 wt .-% of non-monomeric polyisocyanate, based on the total polyisocyanate, obtainable from a) monomeric polyisocyanate by means of a trimerization catalyst in an amount of 0, 1 to 2000 ppm, based on monomeric polyisocyanate, and by means of a stopper in a molar ratio of stopper to trimerization catalyst of 1: 2 to 20: 1.

7. Use of the polyurethane elastomers for the production of cast elastomers such as rollers, wheels, rollers, hydrocyclones, sieves, pigs and cellular and non-cellular elastomers for buffer elements.