DE1595604A1 - Process for the production of polyurethanes - Google Patents

Description

COLORS FA ¹ FKTICeN BAYER AG

ι. One idea

rataat-AbttUua «ffib / BS

Process for the division of polyurethanes

It is known that polyurethanes containing uretdione groups can be crosslinked at elevated temperatures. Of that used in various procedures; be it that you subsequently convert uretdione diisocyanates into crude rubber-like Rolled sheets made of polyurethane compounds are rolled in and vulcanized, be it that uretdione diisocyanates are used from the outset Manufacture of polyurethane compounds while maintaining the uretdione ring and these at elevated temperature such as The »· plastic deformed. Mixtures of diisocyanates and uretdione diisocyanates are used here.

After the casting process "is a polyhydroxyl compound with an excess of uretdione diisocyanates, based on the free NCO groups, reacted at 100-150 ° and the reaction product with chain extenders at the same or brought to reaction at a lower temperature with shaping.

Characteristic of all known processes that involve higher molecular weight Polyhydroxy compounds and low molecular weight polyols as chain extenders on the one hand and

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Uretdione diisocyanates work on the other hand, is that the free NCO groups are present in excess over the OH groups or that the molar ratio in the Is around the equivalence point.

It is surprising that by the process according to the invention, when there is a significant excess of OH groups, based on the free NCO groups, elastic plastics with excellent physical properties can be obtained. The new process for the production of polyurethane plastics from high molecular weight predominantly linear difunktioneilen hydroxy compounds with molecular weights of 800 - 3000, and low molecular weight diols as chain lengthening agents and Uretdione is characterized in that a mixture of difunctional hydroxyl compound and low molecular weight diol at tem- w temperatures below 95 ° with Reacts uretdione diisocyanates in a molar ratio of the OH groups to the free NCO groups of 1.2 to 1.8, then reheats the reaction product at temperatures up to 120 ° until a glassy state is reached, and finally the glassy material at elevated temperature under pressure rbrmgebend baked out.

The higher molecular weight, predominantly linear, difunctional hydroxyl compounds with molecular weights between 800 and 3000 include the known polyethers, polyesters, polyacetals, Le A 9902 8098 "34 / 136U. ₂ -

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Polyester amides or polythioethers. Examples of polyethers that may be mentioned are the polymerization products of tetrahydrofuran, propylene oxide or ethylene oxide and also the addition products of these with divalent starter components. The hexanediol polyethers should also be mentioned. Among the polythioethers, the condensation products of thiodiglycol with itself or with other glycols are of particular importance. Particularly suitable polyacetals are the conversion products of diols with ¹ formaldehyde. Polyesters and polyester amides can be obtained in a known manner from essentially bifunctional alcohols and carboxylic acids, optionally with the use of diamines or amino alcohols. It is also possible to start from polyhydroxy compounds which already contain urethane or urea groups.

All low molecular weight diols are, for example, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 1,4-butenediol, 1,6-hexanediol and hydroquinone di-hydroxyethyl ether called. Of the uretdione diisocyanates, the dimeric 2,4-toluene diisocyanate comes primarily and the dimeric diphenylmethane ^^ 'diisocyanate in question.

The process is expediently carried out in such a way that the components are used in the stated proportions (OH / KCO as 1.2 to 1.8, preferably up to 1.6), optionally with addition

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of fillers at as low a temperature as possible, preferably 55-90 °, until no more segregation can occur as a result of the increase in viscosity. In most cases this is achieved after a few minutes, so that a single roller can be used with advantage. Bas material is filled into containers and reheated at temperatures of up to 120 ° until it is glassy. It is virtually unlimited shelf life in this ψ form and can readily additives at an elevated temperature, preferably 150 - are converted to 170 ° under pressure into elastic moldings which have not been achieved in dtr combination of its physical properties in this class of materials. This applies above all to the relatively low Shore hardness or the low abrasion loss with good tensile strengths.

Examples 1-8:

. 1000 parts by weight. a higher molecular hydroxyl compound (I - IV) are dehydrated at 130 ° and 15 torr and mixed with the tin chain lengthening agent 1,4-butanediol (B) or hydroquinone-di-β-hydroxyethyl ether (H) given in Table 1. Dimer toluene diisocyanate (B) is stirred in the stated amounts into the mixture at 70 ° -80 ° C. for five minutes. The resulting white mass is poured into containers and reheated for six to seven hours at 110-115 ° to form a glassy, storable material and removed from the mold.

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Table 1

example Hydroxylver
binding B. 40 BI 346 1 I. 23.5 112 - 248 2 II 42 - 244 3 II 31.6 - 310 4th II - 116 196. 5 II - 46.4 242 6th II - 116 263 7th III - 608 θ IV -

I ■ * hexanediol adipic acid polyester, OH number 132

II * Polyester urethane from I, by extension with toluene diisocyanate brought to an OH number of 58.8 (corresponding to patent application P 41 990 IVc / 39b)

III * butanediol-1,4-glycol-adipic acid polyester (1: 1: 2), OH number 56

IV = polytetrahydrofuran, OH number 125 The acid number is less than 1 in all cases.

The vitreous storable material thus obtained is pressed in Example 1-5 for 30 minutes at 160 ° to give test specimens 4 mm thick and hot demolded. The material obtained has the following mechanical properties:

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P. Vol Table 2 36 • St. Abr. ■ R «T> - 303 437 b ^ .D El. 30th SR 68 48 1 399 437 5 42 9 73 21 2 304 555 8th 27 29 65 22nd 3 407 415 7th 37 26th 80, 20th 4th 297 475 10 32 63 16 5 6th 17th

Vol.
bl.D.
El.

Tensile strength DIN 53 504 (kp / cm ² ) elongation at break
permanent elongation
Elasticity DIN 53 505
Structural strength, ring (kp) Shore hardness A DIN 53 505
Abrasion loss DIN 35 516

The vitreous materials of Examples 6-8 were given for 60 minutes pressed at 160 ° to a thickness of about 1.5 mm in panels with the following properties.

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Table 3

example 6th 7th 8th Consistency (kp / cm ² ) 420 315 353 Elongation at break (Jl) 440 600 500 Bhor hardness A 69 61 83 ■ · tear resistance
(kp / cm) 50 21 61 [OtTVf *)

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BATH ORIGINAL

Claims (1)

Le A 9902 g sheet 8 t t " Claim: Process for the production of polyurethane plastics from higher molecular weight, predominantly linear bifunctional hydroxy compounds with molecular weights from 800 to 3000, low molecular weight Diols as chain extenders and uretdione diisocyanates, characterized in that a mixture of difunctional hydroxyl compound and low molecular weight diol at temperatures below 95 ° with uretdione diisocyanates in one molar ratio of OH groups to free NCO groups from 1.2 to 1.8 reacts, then the reaction product at temperatures reheated up to 120 ° until a vitreous state is reached and finally the vitreous material at increased Heats out the temperature under pressure in a shaping manner. Le A 9902 - 8 - 909834/1359