DE1145354B - Process for the manufacture of hardened polyurethane elastomers - Google Patents

Description

INTERNAT. Tbsp. C 08 g

GERMAN

PATENT OFFICE

U6755IVc / 39b

NOTICE DAY: DECEMBER 18, 1959

NOTICE
THE REGISTRATION
ANDOUTPUTE
EDITORIAL: MARCH 14, 1963

The invention relates to a process for the production of cured polyurethane elastomers by Curing of the reaction products based on polyesters containing several OH groups an acid number less than 1, polyethers or polyester amides and excess organic Polyisocyanates by curing agents effective at both low and high temperatures under shaping. This method is characterized in that the hardening agents are in the form of Clathrates

1. an inclusive connection with immaterial inert molecular structure and

2. a) a primary amine of the general

formula

R-NH ₂

in which R is an aliphatic saturated hydrocarbon radical having 1 to 8 carbon atoms or a phenyl radical substituted by an amino group, an aminophenyl or an aminobenzyl radical, which can also carry alkyl substituents means, or

b) an aliphatic polyamine with a molecular weight of less than 300 and one Vapor pressure of more than 10 mm of mercury at 170 ° C and less than 5 amino groups, namely primary or secondary amino groups per molecule, or

c) a heterocyclic monoamine of the general formula

R '

, R,

C-R '

in which R is an aliphatic, saturated hydrocarbon radical with 0 to 3 carbon atoms, R 'and R "and Y are hydrogen atoms or aliphatic, saturated hydrocarbon radicals with 1 to 4 carbon atoms are used and that the clathrate at a temperature below its critical temperature is mixed in.

Method of manufacture
of cured polyurethane elastomers

United States Rubber Company,
New York, NY (V. St. A.)

Representative: Dr.-Ing. R. Poschenrieder, patent attorney, Munich 8, Lucile-Grahn-Str. 38

Claimed priority:
V. St. v. America January 23, 1959 (No. 788 527)

Justin James Jecker, West Milford Township, N.J.,

Julian Royden Little, Wayne, NJ,
and John Burkus, Pompton Plains, Morris, NJ

(V. St. A.),
have been named as inventors

In a preferred embodiment of the process according to the invention, the reaction takes place resinous polyhydroxyl compounds with the excess of an organic polyisocyanate in the presence of the clathrate at a temperature below the critical decomposition temperature of the clathrate, and then the mass is cured at a temperature above this critical temperature.

In the process according to the invention, preference is given to using a clathrate with a critical decomposition temperature of at least 10 ° C. above room temperature, but below 170 ° C, applied.

Up to now it has been customary to use water, various glycols and amino alcohols as curing agents for polyurethane elastomers to use. These earlier processes involved a hardener to form of a polyurethane intermediate, however, required that the intermediate very shortly thereafter, because of the limited pot life of this intermediate product.

Therefore, the polyurethane prepolymer and the curing agent had to be stored separately and separately shipped to the consumer for compression molding.

It is also known that certain diamines are effective curing agents for polyurethane elastomers are. So far, however, only the less reactive, higher molecular weight diamines were available

309 539/441

useful. Very reactive diamines, such as ethylenediamine, could not be used because the hardening occurs immediately after contact with the polyester diisocyanate prepolymer occurred and as a result inhomogeneous, overhardened, solid precipitates were obtained on the surface of the sample The interior of this sample was essentially fluid and not hardened. As far as diamines were used, The general procedure was to mix a polyester or polyether with an organic Diisocyanate was reacted beforehand and that the diamine was then added to the prepolymer, to obtain a homogeneous liquid which was then poured into a mold and heated to make the To carry out solidification or hardening. Another method is the prepolymer and then the diamine is added, followed by heating to harden. In this patent a slowly reacting diamine is used to obtain a homogeneous mass, and it is stated that the uncured product containing the diamine is not stable, it is the reason why the diamine is added after molding.

United States Patent 2,620,516 is representative of the prior art. In this patent specification it is said that a fast reacting diamine with a slow reacting organic Diisocyanate and vice versa is used. The method of this patent specification is therefore specific Limited reaction pairs determined by testing in boiling methylene chloride. aside from that a curing time of 4 to 5 hours is required according to this patent. The one in the patent specification given examples show a curing time in the range of 5 to 15 hours. Though nothing about the pot life is given, it is known to be less than 10 minutes, and experiments have shown that for certain combinations mentioned in the patent it is 1 to 5 minutes. After this According to the method according to the invention, it is possible to produce a stable, viscous, plastic polyurethane intermediate product which contains a hardening agent and which is stored and stored for an almost unlimited time can then be shaped and hardened without adding any further reagents. They can do extraordinary things reactive amines and diamines are used as curing agents for polyurethanes, d. H. in other words, connections that were previously unusable. The method according to the invention also gives the ability to reduce the time it takes to cure polyurethane without affecting the temperature significantly, precisely because much more reactive hardeners can be used, with at the same time the advantage is obtained that the pot life of the mixed reactants is greatly extended will.

Any conventional liquid polyurethane prepolymer of the above can be used in the process according to the invention designated type can be used, as shown in the following examples. Detailed descriptions the usual polyurethane prepolymer system can be found in numerous patents and can be found in the literature. In general it can be stated that the liquid used Polyurethane prepolymer a reaction product of an organic polyisocyanate (typically a Diisocyanate, although small amounts of a triisocyanate are used with the diisocyanate can be) with a polyfunctional substance.

This contains terminal hydroxyl groups and usually has a molecular weight in the range of about 300 to about 5000. Most commonly this substance is probably a polyester with an elongated Chain made from a glycol, preferably a mixture of ethylene and propylene glycols,

ίο and a saturated organic dicarboxylic acid, preferably Adipic acid. Usually the glycol contains 2 to 20 carbon atoms and the acid contains 4 to 20 carbon atoms. An excess of glycol is used in the manufacture of the polyester the acid is used so that the polyester obtained contains terminal hydroxyl groups. Usually such an amount of glycol is used that the polyester has a hydroxyl number of from 20 to 225, and preferably 36 to 75 and an acid number less than 6, preferably less than 1, has. The molecular weight the polyester usually ranges from 500 to 5000, and preferably from about 1500 to about 3000. In general, the most useful polyesters are mainly linear and

They have melting points of 90 ° C or lower. ^:

If desired, small amounts of tri-

Alcohols, such as trimethylolpropane or trimethylolethane, are also used in the production of the glycol-dicarboxylic acid polyester, and these modified forms of polyesters are also to be understood under the terms "polyester" or "glycol-dicarboxylic acid polyester" in this description.
Optionally, one or more polyethers can be used with the polyesters just described. These polyethers are typically anhydrous extended chain polyethers that have ether linkages separated from the hydrocarbon chains by either alkyl or aryl.

The ether must also contain end groups that can react with the isocyanate, such as alcoholic hydroxyl groups.

Polyethers can also be used as an additional component of the polyester molecule in the form of the polyether ester be used.

Further examples of polyesters or polyethers which are suitable for the prepolymers are the polyesters and polyethers used in the following U.S. Patents: 2 606162, 2801990, 2 801648 and 2814 606. It is required emphasize that any and all of these known polyethers and polyesters (including polyether polyesters) are suitable for reaction with a diisocyanate to form a polyurethane prepolymer, which can be cured to an elastomeric state by the action of a curing agent .. In addition The polyester and polyether amides are of course also included.

As used in this specification, the term "entrapping compound" denotes compounds that have the ability to reversibly entrap other compounds, thereby forming substances known as clathrates, ie the entrapping compound takes up another molecule or molecules and keeps them in place in an indifferent state. The term "clathrate" is found in "The Encyclopedia of Chemistry", Clark, Reinhold Publishing Corporation, 1957

on pages 249 and 250 and on page 966 as the common crystallization of two substances is defined, the molecules of one substance in solid state form a series of cages in which the atoms or molecules of the second compound fit in, but from which they cannot easily exit. By the dimensions of the educated Cages determine the size and in particular the length of the molecules that act as the second component be considered. The inclusion of a substance in a clathrate takes place without chemical bonding. The type of molecule to be included is determined only by its volume, not its chemical Condition determined (loc. Cit., P. 250). Inclusion compounds or clathrates are not subject to any value restrictions and are solid substances, which one as addition products (without common electrons or electron transfer) from two or can see more of the compounds involved (loc. cit., p. 966, see also Römpp, Chemie-Lexikon, 4th edition, P. 874, and the literature cited there). When a certain condition is met, like one temperature, the clathrate collapses and the previously trapped molecule is released. The temperature at which the substance previously entrapped by the inclusion compound begins to be released in a considerable amount is considered to be the "critical" for the purposes of the invention Temperature «. Enclosing compounds are generally very finely ground, solid substances associated with the compound to be encapsulated, preferably at the critical temperature released as a gas or liquid, can be loaded. One type of the commercially available Inclusion compound is called a "molecular sieve".

They differ from the usual absorbents, such as activated carbon or silica gel, the have no molecular sieve effect. The clathrates, which are very finely crushed, can be mixed with other liquids Substances to which the clathrate is indifferent are mixed without the enclosed hardening agent is displaced by the liquid so that it can be held until the predetermined one critical temperature is reached.

Naturally occurring and synthetic, crystalline MetaHalum mum silicates, which are commercially available as Zeolites are known to exhibit an inclusive function, and this makes them capable of forming CIathrates suitable with hardeners. The enclosing effect is achieved by the original Water from the crystal is removed by heating. Depending on the type of molecules present, d. H. whether they are polar, polarizable or unsaturated, and depending on the conditions under which the Inclusion function takes place, these zeolites show marked or stronger attraction for a particular one Molecular species which is preferred over another, and they are therefore capable of each described Selectively include curing agents of the correct molecular size and shape. The included Substance can be released again by heating the clathrate to its critical temperature.

Synthetic, crystalline zeolites can be produced from a relatively large number of substances, and their formation can be controlled to give the required crystal dimensions. It more or less space can be made available in the molecular pores of the particular zeolite. This unique feature enables certain areas of the crystal pore openings to be preserved and makes these zeolites even more selective in their effect. This still increases their value as a including compounds for hardeners as it provides a useful way to get the zeolites To prepare for their intended use with a special hardener during manufacture.

There are many naturally occurring substances that act as containment compounds. For this include the following: faujasite, chabazite, sodium and potassium mordenite, levynite, and bentonite. Further, Clathrate-forming materials are: hydroquinone, urea, thiourea and deoxycholic acid adducts.

The properties and special configurations of these and many synthetic substances known as Molecular sieves used can be found in the following literature publications. These publications, insofar as they concern the inclusion of substances in other substances, used as a revelation.

1. "Sequestration of Molecules With Aid of Crystal Sieves" by R. M. Barrer in fuel chemistry, 35, p. 325 (1954).

2. "ZeoEtes as Absorbents and Molecular Sieves" by R. M. Barrer in Ann. Reports, 41, p. 31 (1944).

3. "Zeolitic Inclusion Compounds" by R. M. Barrer and W. M. Meir in HeIv. Phys. Acta, 29,

P. 229 (1956).
35

4. "Salt Inclusion Complexes of Zeolites" by R. M.

Barrer and W. M. Meir in J. Chem. Soc, 1958, p. 299.

5. "Inclusion Complexes of faujasites With paraffin ■ '· and permanent gas" by Barrer and Sutherland in Proc Roy. Soc., 237, p. 439 (1956).

6. "Crystalline Zeolites" by Breck et al.

I Properties J. Am. Chem. Soc, 78, p. 5963

(1956).

II Crystal Structure J. Am. Chem. Soc, 78,

P. 5972 (1956).

In the aforementioned references, methods for "loading" inclusion compounds specified.

Suffice it to say for the purposes of the present invention that a suitable enclosing compound is any substance which is indifferent to polyesters, diisocyanates and the particular curing agents used and which can enclose the molecules of the particular curing agent used to render it substantially indifferent to diisocyanates .
The use of encapsulating compounds which form clathrates with hardeners is of particular importance in the use of amine-type hardeners to cure polyurethane elastomers, as this makes it possible for the first time to use a very reactive amine-type hardener in a useful manner, the can be mixed with the polyurethane prepolymer to form an intermediate product which is stored for a very long time and yet in one time

can be shaped and cured into a stable elastomer in a few minutes.

The molecular weight limit is given to only react relatively quickly Include connections. The vapor pressure limitation is necessary because 170 ° C is close to the is the highest practical curing temperature for most intermediate products and the curing agent must be released before it can be used with the Polyester diisocyanate prepolymer can react.

Examples of suitable hardeners are the following: the phenylenediamines, the tolylenediamines, 4,4-Diphenyldiamine, 4,4-DiaminodiphenyImetahn, Ethylenediamine, 1,3-Propylenediamine, 1,2-Propylenediamine, Tetramethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenitetramine, trimethylenediamine, Diethylenediamine, 3,3'-bis-aminopropylamine, Ν, Ν'-dimethylethylenediamine, N, N'-diethylethylenediamine, 1,4-diaminobutene-2, durenediamine (1,2,4,5-tetramethylbenzenediamine), methylamine, ethylamine, Propylamine, butylamine, isobutylamine, tert-butylamine, Isopropylamine, dimethylamine, trimethylamine, ethyleneimine, trimethyleneimine, pyrroudine or piperidine.

In general, any conventional method of "loading" molecular sieves, such as e.g. B. in the above Literature is described, can be used. The method according to the invention, however, for has been found to be particularly beneficial as it is very simple, yet satisfying, is the following:

The entrapping compound, generally in powder form or in a very finely divided state is dried by heating to 343 ° C in a stream of dry nitrogen. If that to

ίο hardening agents used are gaseous or vaporous Is substance, the enclosing compound is then placed in a reaction vessel and the Pressure is reduced to about 5 mm of mercury, and then one atmosphere is removed from the visible Connection created in the reaction vessel so that the pressure is reduced to approximately 500 mm Mercury is raised. This state is maintained for several hours, and then becomes Blasted nitrogen until atmospheric pressure is reached. It is observed that the pressure in falls in the reaction vessel as the hardener is taken up by the inclusion compound. The amount absorbed by the inclusion compound is calculated according to the following equation:

% Hardener in clathrate =

Weight of the clathrate - weight
the dry enclosing joint

Weight of the clathrate

If a curing agent is to be included, this is usually one at room temperature Liquid, the above procedure can be applied by simply adding the liquid hardener in the reaction vessel is done and the pressure is reduced so that the curing agent is gaseous will. If necessary, the temperature can be increased a little. When the curing agent to be included does not readily evaporate under these conditions can be, it can be dissolved in a non-polar solvent, and the enclosing compound is added to this solution, it is preferred to use the polar compound (hardener) Pick up point of non-polar solvent. After a certain time, the non-polar solvent can are filtered off, and it remains the CIathrate.

The amount of the added to the prepolymer or polyester, whichever is used Curing agent must be carefully controlled to prevent over or under curing. The required amount of the hardening agent varies depending on the kind used. In the case of primary monoamines must have 0.20 to 0.5 equivalents of curing agent per equivalent of reactive Isocyanates can be used. In the case of secondary and tertiary monoamines, 0.1 to 1.0 equivalent of curing agent used per equivalent of reactive isocyanate. In the case of polyamines 0.5 to 1.0 equivalent per reactive isocyanate must be used. 1 equivalent Amine is calculated by dividing the molecular weight by the number of active amino groups will. In the case of aromatic polyamines, the number of primary amino groups per molecule becomes Calculation used. In the case of aliphatic polyamines, the total number becomes primary plus secondary amino groups used per molecule. The number of equivalents of reactive Isocyanates can be calculated using the stoichiometric equation or by Reaction with di-n-butylamine according to the method of Stagg (Analyst, Vol. 71, p. 557 [1946]).

The amount of the entrapping compound necessary to match the amount of the amine curing agent should not be so excessive as to affect the physical properties of the polyurethane elastomer adversely affected, but neither should it be so small that it overloads with the resulting premature release of the curing agent or inability to use all of the curing agent to release within the required time results. It was found that a lot of the hardener from 5 to 20 percent by weight of the clathrate (including compound and hardener) depending on the particular system of curing agent and containing compound for those of the invention Purposes is ideally suited.

The critical temperature of the clathrate is the temperature at which the trapped Substance begins to be released in considerable quantities. This can be for any particular clathrate be determined by placing 100 g of the substance in a dry vessel and then nitrogen is passed through with heating. The temperature at which the sample gained significant weight begins to lose is the critical temperature. This critical temperature tends to increase with the Composition of the clathrate to vary. Following the above procedure, the following was found: For ethylenediamine, that in an amount of 12 percent by weight in an enclosing compound of the following composition (expressed in oxides)

Na ₂ O: Al ₂ O ₃ : 2.67 SiO ₂ : n H ₂ O

is included, the critical temperature was found to be about 80 ° C.

9 10

When carrying out the process according to the invention, the curing temperature is generally un-

driving is maintained for 30 to 60 minutes with the hardener to be used,

first a clathrate with any enclosing Da the highest useful curing temperature

Connection established in the manner described above. about 170 ° C and because it goes without saying

The powdery or finely ground clathrate is required for the polyurethane intermediate

It is not technically possible to store it in a normal, liquid polyester diisocyanate at room temperature

anate reaction product or prepolymer is desired, a clathrate with a critical temperature

greed. Another method can be used with a good temperature above 170 ° C or one with a

Results are obtained if the temperature in the area of the Zirmner

Inclusion compound loaded with medium directly to temperature or below. Preferably the critical

the polyester is added before the polyester is at a temperature of at least 10 ° C above room temperature.

the diisocyanate is reacted. This process temperature are.

stage can be carried out at room temperature with stirring. Further details of the invention are given in the

are carried out and gives a dispersion; Embodiments given,

then the diisocyanate is used in the usual way 15

regardless of the presence of the hardening example I.
by means of added to the polyester, with the exception that the temperature of the mass is kept during the 1 mole of a polyester with the total molecular weight of the addition below the critical temperature and an acid number below 1, prepared from the temperature of the clathrate. The advantage of this 20 adipic acid and a 70:30 mixture of ethylene process is that the clathrate, because of the propylene glycol and 2.2 moles of toluene diisone, has a lower viscosity of the polyester compared to cyanate 1 hour at 100 ° C with a prepolymer the viscosity of the polyester prepolymer implemented.

and diisocyanate can be dispersed more easily. Implementation according to the invention

Temperature at which the clathrate to the poly-25

ester or prepolymer, depending on what is used 80 parts by weight of this prepolymer

it is added is not very important. at room temperature in a dry reaction

The only restriction is that this temperature is brought to the vessel, and in it are 13.53 parts by weight

thoroughly dispersed below the critical temperature of the clathrate of an enclosing compound

must lie. Preferably, the addition of the Cla- 30 is gated - as an enclosing compound was a

thrates at a temperature of at least 10 ° C commercial product similar to the faujasite used, which,

given below the critical temperature of the clathrate in oxides, the following composition

carried out. Therefore, the addition in Zimmerzung can have:

temperature or at an elevated temperature, the Na ₂ O: Al ₂ O ₃ : 2.67 SiO ₂ : η H ₂ O

in some cases up to 100 ° C can go through 35

be guided. If the clathrate has during the polyurethane diameter of 12 Å, the 15 "Vol 80 equivalents of curing agent per equivalent dispersion appears because of the small size of the 40 unreacted isocyanate in the prepolymer. Clathrate particles are homogeneous. that essentially its liquid character and then it will still be a viscous liquid. The not more viscous, but it retains essentially viscous liquid was then lent into a form the relatively low viscosity of the 45 poured and 1 hour at a pressure of 280 kg / cm ² prepolymer, for an unlimited time on 1 63 ° C heated.

at room temperature or even above room temperature when it was removed from the mold. Repeatedly temperature-held elastomers can give a good appearance. After a below the critical temperature of the clathrate, post-curing period of 14 days in air with room heated with no other effects on temperature, the cured sample had a Shore A tread than the reduction in viscosity at high durometer hardness of 70 and a final breakage rate Temperatures as expected. This viscose elongation of 310%.

The change in rate is easily reversible, so that the liquid was 80% by weight polyurethane intermediate when it cools down, parts of the same prepolymer at Zimmer adopts its original viscosity. 55 temperature brought into a dry reaction vessel. If the polyurethane intermediate was too high, then 1.76 parts of ethylenediamine became critical Temperature of the clathrate added heated. It got an instant response and the hardener will be observed from inclusion solidification on the surface of the mixture released, and the hardening begins and respects. Below this reacted mass, the poly remained a polyurethane elastomer which is liquid after the transfer. Continued stirring served only lent post-curing period excellent physical to break up the surface and the solid particles Properties shows. Swirling the polyurethane intermediate in the liquid. After 10 minutes can, if necessary, before hardening or the same - the stirring was stopped and the mass in be formed early with it. Preferably the one mold is poured and heated. When opening the Polyurethane intermediate product at a temperature 65 mold showed that the entire mass did not harden, which was set at least 10 ° C above the critical, indicating that essentially that The temperature of the clathrate and generally all of the ethylene diamine is local on impact at a temperature of not less than 140 ° C. the surface of the prepolymer had reacted.

1 145 354 12th 11 Example V Example II

90 parts of the prepolymer prepared as in Example IV were poured into a dry vessel 5 stainless steel, and 19.6 parts by weight of the same containing compound therein as in Example I in which 13.5% isobutylamine was included. This gives a Ratio of 0.40 equivalents of hardener per

hardened with a tough elastomer. Example VI

A viscous liquid was produced which
Polyester, diisocyanate and clathrate in the same
Amount ratios contained as in Example I. These
Liquid was then plugged into a dry
Poured bottle. Nitrogen was passed over the liquid in order to exclude any water vapor,
and the bottle was capped and stored at room temperature. At intervals of 4 weeks, 10 equivalent of unconverted isocyanate in the preheating was the bottle in hot water on a temperature polymer.

only heated to about 50 ° C. The viscous liquid remains viscous after mixing

The fluid in the bottle thinned each time and fluid with no evidence of a hardening reaction flowed easily on the sides of the bottle. When the viscous liquid was then cooled in a shaped bottle, the liquid was poured and heated to 172 ° C for 1 hour. Viscous again after discharge, as before. In a time of 4 weeks removal from the mold, the prepolymer was no increase in viscosity, neither
observed at room temperature still at 50 ° C.
This example shows the great stability that is obtained according to the invention, in contrast to the un- 20 90 parts of the precondition prepared as in Example IV, the same substances are excreted by the over-polymer in a dry vessel

stainless steel, and 10.7 parts of the same containing compound as in Example I with 15.0% triethylamine included therein is dispersed therein. This gives a ratio of 0.30 equivalents of the curing agent per equivalent of unreacted isocyanate in the prepolymer. The material remains a viscous liquid after mixing with no evidence of a hardening reaction.

Bonding as in Example I, which had 15% ethylene-30 The viscous liquid was poured into a mold and had taken up diamine, heated to 150 ° C. at room temperature and for 1 hour. After removal of 200 parts by weight of a polyether diisocyanate adduct (1 mole of polytetramethylene glycol with a molecular weight of 900, reacted with 1.5 moles of tolylene diisocyanate) with a molecular weight of 2320 zzug- 35
give. The mixture became homogeneous
Stirred dispersion. The viscous liquid obtained
was divided into two parts. One part was at 163 ° C
Cured for 60 minutes and yielded an elastomer with

good physical properties. The other part 40 13.1% ethyleneimine are included, dispersed. was poured into a stoppered bottle and this gives a ratio of 0.4 equivalent of curing agent per equivalent of unreacted isocyanate.

The material remains a viscous liquid after mixing with no evidence of hardening reaction. The viscous liquid is then poured into a mold and heated to 150 ° C for 1 hour. After removal the prepolymer was hardened from the mold to form a tough elastomer. After a post

Liche procedures, as in the control experiment of Example I to implement.

Example ΠΙ

In order to show that the invention is also applicable to a typical polyether blend, were 25.99 parts by weight of the same including

the prepolymer was hardened from the mold to form a tough elastomer.

Example VII

90 parts of the prepolymer used in Example IV are placed in a reaction vessel, and therein 10.9 parts by weight of an including compound (as in Example I), in the

Stored for 3 weeks at room temperature; when the viscosity was then checked it was found to be the same as it was before storage.

Example IV

1 mole of a polyester with a molecular weight of 1980 and an acid number below 1, made from

Adipic acid and a 70:30 mixture of ethylene- 50 curing time of 14 days in air at room temperature- and propylene glycol, with 2.2 moles of toluene temperature, the cured sample had the following self-diisocyanate Reacted for 1 hour at 100 ° C to take advantage of:

known method to produce a prepolymer. 90 parts by weight of this prepolymer was placed in a dry stainless steel vessel at room temperature, and 36 parts by weight of the same enclosing compound as in Example I, in which 20% 4,4 ^/ -diaminodiphenylmethane was included, was well dispersed therein. This results in a ratio of 0.8 equivalents of curing agent per equivalent of unreacted isocyanate in the prepolymer.

The material remains a vissous liquid after mixing with no evidence of a hardening reaction. The viscous liquid is then poured into a mold and heated to 170 ° C for 1 hour.

After removal from the mold, the prepolymer had hardened to form a tough elastomer.

Shore A durometer hardness 60

Elongation at break 360%

Claims (3)

PATENT CLAIMS: 1. A process for the production of cured polyurethane elastomers by curing the reaction products based on polyesters containing several OH groups with an acid number of less than 1, polyethers or polyester amides and excess organic polyisocyanates by means of curing agents that are effective at both low and high temperatures, with shaping, characterized in that the hardeners are in the form of clathrates 10 1. an enclosing compound having a substantially inert molecular structure and 2. a) a primary amine of the general formula R-NH ₂ in which R is an aliphatic saturated hydrocarbon radical with 1 to 8 carbon atoms or a phenyl radical substituted by an amino group, an aminophenyl or an aminobenzyl radical, which can also carry alkyl substituents means, or b) an aliphatic polyamine with a molecular weight of less than 300 and a vapor pressure of over 10 mm of mercury at 170 ° C and less than five amino groups, namely primary or secondary amino groups per molecule, or c) a heterocyclic monoamine of the general formula R "- C C-R ' in which R is an aliphatic, saturated hydrocarbon radical with 0 to 3 carbon atoms, R 'and R "and Y are hydrogen atoms or aliphatic, saturated hydrocarbon radicals having 1 to 4 carbon atoms mean, are used and that the clathrate at a temperature below its critical temperature is mixed in. 2. The method according to claim 1, characterized in that the implementation of the resinous Polyhydroxy compounds with an excess of an organic polyisocyanate in the presence of the clathrate at a temperature below the critical decomposition temperature of the clathrate takes place and then the mass at a temperature above this critical temperature is cured. 3. The method according to claim 2, characterized in that a clathrate with a critical Decomposition temperature of at least 10 ° C above room temperature, but below 170 ° C, is applied. Considered publications:
German Patent Nos. 913 474, 946173; German Auslegeschrift No. 1022 376;
U.S. Patent No. 2,634,244;
Römpp, "Chemielexikon", Stuttgart, 1952,
P. 351. A priority document was displayed when the registration was announced. © 309 539/441 3.63