DE1900513C3 - Stabilization of organic isocyanates - Google Patents

Description

SO ₁ -NCO

is known and is described in U.S. Patent No. 3330849. Additions of 0.5 to 5% of these sulfonyl isocyanates to aryl or alkyl! isocyanates not only a higher light stability, but also prevent a change in the diisocyanates at the same time, which is caused by di-, tri- or polymerization of the NCO groups and which is longer Storage or faster at temperatures of 50 to 100 C often made noticeable by the fact that in the Isocyanates separates a sparingly or insoluble precipitate. The changes suffer in particular the aromatic diisocyanates, which makes their processing difficult.

The proportion of z. B. during storage resulting di- or polymerization products is usually dependent on the constitution of the aromatic diisocyanate. It occurs especially at room temperature after a long storage time with the 4.4'-DiphenyImethandiisocyanat and affects z. B. visible, inter alia, in a decrease in the NCO content. As a result, it is difficult to obtain reproducible results in the production of macromolecular products, for example polyurethane elastomers, with such a stored diisocyanate. to achieve.

These difficulties can largely be eliminated if stabilization is carried out with sulfonyl isocyanates Isocyanate works. Polyurethane elastomers are obtained from diisocyanates stabilized in this way but have a significant disadvantage. They have a lower hydrolysis stability

45 liity to depen obtained from non-stabilized diisocyanates. Even after a period of hydrolysis aging at 70 ° C. and 95% humidity, a considerable drop in mechanical properties can be observed. The low hydrolytic stability is due to the stabilizer (the sulfonyl isocyanate), the hydrolysis end product of which catalyzes the hydrolytic degradation of the elastomer.

Surprisingly, it has now been found that isocyanates containing at least one

- O - CO - NCO group

contained in the molecule, an excellent Siabiiisierungsffekt for isocyanates show, d. that is, they prevent the formation of di- and polymerization products in storage and / or at elevated temperatures, differ from sulfonyl isocyanates !! but in their stabilizing effect also because the lightfastness of the stabilized isocyanates significantly improved and the hydrolysis stability of the high molecular weight which can be prepared from the stabilized isocyanates Products, e.g. B. of polyurethane elastomers, is increased significantly.

The present invention is therefore the use of compounds that at least contain an —O - CO - NCO group in the molecule, to stabilize organic isocyanates.

To achieve a sufficient stabilizing effect, In many cases, even relatively small amounts are sufficient, e.g. B. from 0.1 to 5 percent by weight, according to the invention isocyanates to be used, the. z. B. when they are crystallized, into the melted one or liquid isocyanate to be stabilized can be stirred in. The isocyanates stabilized in this way are at room temperature and at elevated temperature for several months without the formation of Polymerization products can be kept unchanged and hardly yellow in the light. Also the solution of the stabilized isocyanates in solvents that do not contain any isocyanate-reactive groups Can be kept unchanged under the above conditions.

The oxycarbonyl isocyanals to be used according to the invention are prepared according to known methods Procedure, e.g. B. either by the action of oxalyl chloride on unsubstituted nitrogen Carbamic acid ester

ROOC "NH ₂ + (COCl) ₂ -ROOC • NCO + CO ₂ + 2HCl

according to the procedure of the accompanying patent specification 6 76 352.

Compounds using 7U according to the invention with at least one - O CO NCO group

H <, C ₂ OOC NCO

OCN OCO (CH ₂ I ₄ OCO NCO

CH ₁ - (CH ₂ ) ,, -OCONCO

CH ₂ OCO NCO CH, CH ₂ C CH ₂ O (O NCO

CH ₁ -OCO NCO

are of any kind. Aliphatic and aromatic Mono- and or di-oxycarbonyl isocjanates are preferred. The following are mentioned as examples

Boiling point 120 to 121 C 760 mm
Boiling point 120 to 122 C 0.5 mm
Boiling point 122 C 0.04 mm

Boiling point 160 C 0.05 mm

H ₁ C

OCO NCO

Boiling point 1 15 to lift C 15 mm

19 OO

V- OCO-NCO

OCN-OCO

Boiling point 138 to 139 C 0.09 mm

OCN OCO h ^ h ^ermole BT Hydroxyve rbind Ungen

z. BT molecular weight 2000

_n _ _rn

Isocyanates to be stabilized according to the invention are of any type and are aliphatic. cycloaliphatic, Araliphatic and aromatic mono. Di-. Tri- and higher-valent isocyanates. Diisocyanates are preferred z. B. 4,4-diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, hexamethylene diisocyanate. Hexahydro-p-phenylene diisocyanate. isophore diisocyanate. The reaction products of isocyanates with hydroxy compounds are also possible, so-called prepolymers which still contain free NCO groups. As such, for example Prepolymers made from higher molecular weight polyethers or polyesters with diisocyanates or reaction products of bi- and tri-functional low molecular weight H) hydroxy compounds with an excess called on diisocyanates. Obtained by aniline formaldehyde and subsequent phosgenation Polyaryl-polymethylene-polyisocyanates also come into consideration. 4,4'-Diphenylmethane diisocyanate is preferred.

Examples:

Comparative experiment 1

In 200 g of an ethylene glycol adipic acid polyester dehydrated at 130 ° C. for 12 mm (OH number 56) are 80 g of non-stabilized 4,4-diphenylmethane diisocyanate at 130.degree stirred in and reacted at 130 to 140 ° C. in 20 minutes. Then you pour into the Melt 18 gliutanediol-1.4 with thorough stirring and pour the homogeneous melt into prepared molds. It freezes after a few minutes and After 24 hours of post-heating at 100 ° C., it provides an elastomeric plastic with the following properties .

Tensile strength (kg cm ² ) 299

Elongation (%) 512

Permanent elongation (%) 11

Load at 300% (kg cm ² ) 95

Tear strength (kg cm) 52

Hardness (Shore A). "77

Elasticity 36

After 14 days of hydrolysis aging at 70 ° C. and 95% humidity, these plastics measured the following values:

Strength (kg cm ² ) 225

Elongation (%) 545

Permanent elongation (%) .... 22

Load at 300% (kg cnr) 75

Tear strength (kg cm) 42

Hardness (Shore A) .. ". 77

Elasticity 3S

example 1

In 5 kg of a freshly distilled, molten 4.4'-Diphenylmethandiisocvanate at 50 to

C 50 g

CH ₃ (CH ₂ J ₁₂ - CH ₂ O

CO - NCO

stirred in. The melt solidifies when it cools. The stabilized diisocyanate melts at 39 to 43 C and has an NCO content of 33.2%.

Under the conditions and proportions given in Comparative Example 1 was below Use of the stabilized diisocyanate to obtain an elastic plastic with the following properties:

Tensile Strength (kg cnr) 322

Elongation (%) 655

Permanent elongation (%) 20.5

Load 300% (kg cnr) 88

Tear strength (kg cm) 80.5

Hardness (Shore A) .. T 79

Ek-stiziläi 37

After 14 days of hydrolysis aging, the following values were measured on these plastics:

Tensile strength (kg cm ² ) 235

Elongation (%) 682

Permanent elongation (%) 33

Load at 300% (kg cnr I 6S

Tear strength (kg cm) 53

Hardness (Shore A) 76

Elasticity 43

Comparative experiment 2

Among the in the example! specified conditions and menene ratios, but using a 4,4'-diphenylmelandiisooanate stabilized with 1% p-toluenesulfonyl isocyanate according to the USA patent specification 33 30 849, an elastic plastic was obtained with the following properties:

Tensile Strength (kg cnr) 317

Elongation (%) 598

Permanent elongation (%) 16

Load at 300% (kg; cnr) 92.5

Tear strength wedge (kg cm) 66

Hardness (Shore A) 82

Elasticity 39

After 14 days of aging by hydrolysis, this plastic measured the following values:

Tensile Strength (kg cnr) 172

Elongation (%) 672

Permanent elongation (%! "6.5

Load at 300% (kg cnr) 64

Tear strength (kg cmi 33

Hardness (Shore A) ⁷ 5

Elasticity 34

As can be seen from Comparative Example 2. takes place during the hypolysis allergy a strong Decrease in tensile strength and tear strength. Find hydroh tic degradation also speaks the height of the dei permanent elongation (76.5%).

35

19 OO 513

* ο

^ Solution in

rhhirbenzol 1. after 4 weeks Light stabilization

aj comparison c) comparison

The color number of the unstabilized 4.4'-diphenyl-5 ·, _a ,

methandiisoeyanates <! 00%; was 1, after 4 weeks the harb / ahl des mil I / "

Chen 2: the 2 ()% solution in chlorobenzene 1. after ---

4 weeks 2. H, C <^> S (J ₂ - NC CJ

b) The color number of the according to (3 Example 1 with 1 % _{| Q}

si-ibilisicrtcn 4,4'-Diphcnylmethandiisoc \ anate> Iv-CH ₃ - (CH ₂ J ₁₂ -CH ₂ - CO O - NCO | _{fug, b} j _s2 .'nach4 weeks 3; the 2Ü% igcn LiiMing

stabilized 4.4'-diphenylmethane diisocyanate, chforbenzene 1 to 2 after 4 weeks

Claims (1)

Claim: Use of compounds that have at least one - O - CO - NCO group in the molecule contain, to stabilize organic isocyanates. 20th The stabilization of aromatic and aliphatic isocyanates by adding sulfonyl isocyanates such as p-toluene sulfonyl isocyanate