DE1794108B2 - METHOD FOR STABILIZING POLYURETHANES - Google Patents

Description

AQ

where T is a tertiary alkyl radical, e.g. B. a tert-putyl, tert-amyl-, tert-octyl- or tert-dodecyl- ■ est, A is a primary or secondary alkyl radical having 1 to 12 carbon atoms or the radical T, R one primary alkyl radical of 1 to 12 carbon atoms or • an aralkyl radical, Q an OR radical, T or A • nd X hydrogen or a residue

The invention relates to a method for stabilizing polyurethane elastomers, preferably Polyurethane threads and foils, against degradation and discoloration when exposed to light or UV rays, oxygen, atmospheres, e.g. B. nitrogen oxides and heat by adding alkoxy-substituted, Seriously hindered phenols with the structural segment of a 2- (2'-hydroxy-3'-tert-alkylbenzyl) -anisole group:

OH

OCH,

OH

represents, where in the case of Q = alkyl the radical —CH ₂ · X is in the 6 position and in the case of Q = OR radical the radical —CH ₂ · X is in the 5 position, as stabilizers for polyurethane elastomers in amounts of 0, 05 to 10 percent by weight, based on the polyurethane elastomers, can be used.

2. The method according to claim 1, characterized in that that sterically hindered phenols of the formula

OH OCH ₃

CH, X

45

where Q is a primary alkyl radical from I to 8 carbon atoms or a methoxy radical and X a radical of the formula

OH

C (CH ₃ ) ₃

55

60

means as stabilizers for polyurethane elastomers in amounts of 0.05 to 10 percent by weight, based on the polyurethane elastomers.

as stabilizers.

Polyurethanes, which are made from higher molecular weight polyhydroxy compounds. Polyisocyanates and chain extenders in the form of foams, Elastomers, coatings, foils or elastomer threads are widely used - to a certain extent Dependence on their structural components - against the effects of light, but also to some extent in air at higher temperatures, unstable and are thereby degraded in their strength values, in many cases there is also strong discoloration of the polyurethanes.

Many efforts have been made by adding known antioxidants such. B. phenol-based, a to achieve some protection against discoloration and degradation, but this stabilization is generally unsatisfactory.

So were z. B. Phenols such as 4,4'-alkylidene-bis- (6 - tertiary - butyl - m - cresol), 2,6 - di-tertiary butyl-4 - methylphenol or 4,4'-methylene - bis - (2,6 - di-tert-butylphenol) have been tested as stabilizers, but these show either a disruptive initial discoloration or a failure of protection against discoloration when exposed to light or atmospheres. Furthermore, polyphenols, such as. B. 1,3,5-trimethyl - 2,4,6 - tris - (3,5 - ditertiary butyl - 4 - hydroxybenzyl) benzene used as stabilizers (DT-AS 12 43 866). In addition, a number of phenolic compounds were named, which together with hydroxybenzophenones to be suitable for stabilizing polyurethanes (DT-AS 11 06 490). However, the effect of these phenolic stabilizers is insufficient, not washable or washable. such stabilizers have an inherent color that z. B. is unsustainable for white elastomeric threads.

Other phenolic stabilizers for polyurethanes are described in US Pat. No. 3,072,605. However, these differ structurally from the stabilizers according to the invention in that they Do not allow a combination in which there is once an OH group in the 2,2 'positions to the alkylidene group and on the other hand are an alkoxy radical, and the stabilizers of US Pat. No. 3,072,605 apparently only sufficiently effective when combined with phosphoric acid can be used. They are the stabilizers used according to the invention in the stabilizing Inferior effect. This already results from the fact that in the below listed Tables contain stabilizers which are closer to those used according to the invention than to those of

US-PS 30 72 605 and still not the effectiveness of the stabilizers used according to the invention reach out.

A new class of phenolic stabilizers has now been found which, on the basis of their typical structure enables a highly effective stabilization of polyurethanes, these stabilizers are colorless, do not cause discoloration in the polyurethane and have a significantly improved, wash-resistant protection against discoloration and degradation when exposed to light and / or Cause atmospheric lilies.

The invention relates to a process for stabilizing polyurethane elastomers by means of sterically hindered phenols, characterized in that alkoxy-substituted, sterically hindered phenols of the formula

OH OR

CH, X -CH-, ■ X is in position 6 and in the case of Q = OR radical the radical -CH ₂ · X is in position 5, as stabilizers for polyurethane elastomers in amounts of 0.05 to 10 percent by weight, based on the polyurethane elastomers, can be used. Stabilizers of the formula 11 are preferred

OH

CH ₁ • X

for use, where Q is a primary alkyl radical. preferably a methyl resl, a tertiary alkyl radical, preferably a tertiary butyl or tertiary octyl radical, or a methoxy radical and X a

OH

25th

where T is a tertiary alkyl radical, e.g. B. a tert-butyl, tert-amyl, tert-octyl or tert-dodecyl radical, A is a primary or secondary alkyl radical having 1 to 12 carbon atoms or the radical T, R is one primary alkyl radical of 1 to 12 carbon atoms or an aralkyl radical, Q an OR radical, T or A and X is hydrogen or a residue

OH

represents, where in the case of Q = alkyl the remainder .Rest

CH ₃

and for the position of CH ₂ ■ X in relation to the substituent Q, the above conditions apply.

Preferably 0.2 to 3 percent by weight of the above stabilizers, based on the polyurethane elastomers, used.

The phenolic compounds used are novel compounds and can be passed through Implementation of 2-tert-alkyl-4-aIkylphenolen with o-Hydroxymethylaikoxybenzenes in the presence of catalytic Produce quantities of strong acids with elimination of water in a non-claimed manner, for example according to the following reaction equation:

OH

OCH ₃ OH

HO · H ₂ C

CH, · OH

Alkyl

p-Toluenesulfonic acid, "". ~

in sied. toluene

The major improvement made by using the alkoxy-substituted, sterically hindered Phenols is achievable, is in comparison tests against corresponding compounds, which at Place of the alkoxy substituent carry a free hydroxyl group, shown. In the comparison tests a phenol: 1,3,5-trimethyl-2,4,6-tris- (3,5-di-tert-butyl-4-hydroxybenzyl) -benzene is also included, that of the previously known phenolic compounds as one of the relatively most effective phenolic compounds can be seen (DT-AS 12 43 866).

It shows, among other things, that equivalent phenols such. B. trisphenol

OH

OH

OH

CH,

C (CH ₃ ).,

compared to the Stabili used according to the invention Sator »A«, which contains an alkoxy radical in place of the middle hydroxyl group, when exposed to UV light show a strong Eigenverfarbur.g (yellow) and thus stabilize colorless polyurethane elastomers are unsuitable. In addition, the alkoxy-substituted phenols used according to the invention show a better stabilization against degradation than z. B. the purely phenolic stabilizer 1,3,5-trimethyl-2,4,6-tris (4-hydroxy-3,5-di-tert-butylbenzyl) -benzene (according to DT-AS 12 43 866).

As alkoxy-substituted to be used according to the invention to stabilize the polyurethanes. steric hindered phenols, for example, the following compounds are suitable:

2,4-dimethyl-6- (2'-hydroxy-3'-tert-butyl-5'-methylbenzyl) -obenzylphenol,

2,4-dimethyl-6- (2'-hydroxy-3'-tert-butyl-

5'-methylbenzyl) anisole,
2-methyl-4-tert-butyl-6- (2'-hydroxy-

3-tert-butyl-5'-methylbenzyl) -anisoI, 2-methyl-4-tert-amyl-6- (2'-hydroxy-

3'-tert-butyl-5'-methylbenzyl) anisole, 2-methyl-4-tert.octyl-6- (2'-hydroxy-

3'-tert-butyl-5'-methylbenzyl) anisole, 2-methyl-4-isononyl-6- (2'-hydroxy-3'-tert-butyl-5'-methylbenzyl) anisole.

2-methyl-4-tert-dodecyI-6- (2'-hydroxy-

3'-tert-butyl-5'-methylbenzyl) anisole. 2-methyl-4-isododecyl-6- (2'-hydroxy-

3'-tert-butyl-5'-methylbenzyl) anisole. 2-methyl-4-tert-butyl-6- (2'-hydroxy-

3'-tert-butyl-5'-methylbenzyl) -o-benzylphenol, 4-methyl-2,6-bis- (2'-hydroxy-3'-tert-butyl-

5'-methylbenzyl) anisole,
4-methyl-2.6-bis (2'-hydroxy-3'-tert.amyl-5'-methylbenzyl) anisole,

4-methyl-2.6-bis (2'-hydroxy-3'-tert.octyl-

5'-methylbenzyl) anisole.
4-methyl-2.6-bis- (2'-hydroxy-3'-tert-dodecyl-

5-methylbenzyl) anisole.
4-methyl-2,6-bis (2'-hydroxy-3'-tert-butyl-

5'-methylbenzyl) -butoxyphenol, 4-tert-butyl-2,6-bis- (2'-hydroxy-3'-tert-butyl-

5'-methylbenzyl) anisole.
4-tert-butyl-2,6-bis (2'-hydroxy-3'-tert-amyl-5'-methylbenzyl) anisole.

4-tert-amyl-2,6-bis- (2'-hydroxy-3'-tert-butyl-

5'-methylbenzyl) anisole,
4-tert-octyl-2,6-bis- (2'-hydroxy-3'-tert-butyl-

5-methylbenzyl) anisole,
4-tert-dodecyl-2,6-bis- (2'-hydroxy-3'-tert-butyl-

5-methylbenzyl) anisole.
4-isononyl-2.6-bis- (2'-hydroxy-3'-tert-butyl-5'-methylbenzyl! -Anisole.

4-isopropyl-2,6-bis- (2'-hydroxy-3'-tert-butyl-

5'-methylbenzyl) anisole,
4-methyl-2,6-bis (2'-hydroxy-3'-tert-butyl-

5'-methylbenzyl) -o-benzyiphenol,
2.5-bis- (2'-hydroxy-3'-tert-butyl-5'-methyl-

benzyD hydroquinone dimethyl ether,
2,5-bis- (2'-hydroxy-3'-tert.amyl-5'-methyl-

benzyl) hydroquinone dimethyl ether,
2.5-bis- (2'-hydroxy-3'-tert.octyl-5'-methyl-

benzyl) hydroquinone dimethyl ether,
2,5-bis- (2'-hydroxy-3'-tert-dodecyl-5'-methyl-

benzyl) hydroquinone dimethyl ether,
2.5-bis- (2'-hydroxy-3'-tert-butyl-5'-isopropyl-

benzyl) hydroquinone dimethyl ether or
2.5-bis- (2'-hydroxy-3'-tert.butyl-5'4ert.butyl-

benzyD hydroquinone dimethyl ether.

The elastic polyurethanes to be stabilized, which may be in foamed form, can be prepared by known processes and from known starting materials. The polyurethanes are generally made by reacting higher molecular weight polyhydroxy compounds (e.g. polyester or polyether with a molecular weight of about 500 to 5000. Melting points preferably below 60 "C) and aliphatic, araliphatic or aromatic polyisocyanates (preferably aromatic diisocyanates such as toluene diisocyanate or diphenylmethane - 4.4'-diisocyanate) and so-called chain extenders, d. H. low molecular weight compounds (molecular weight e.g. 18 to 400) with two or more, groups that are reactive towards isocyanate (e.g. low molecular weight diols, diamines, dihydiazides or the like) Connections such as B. Amino alcohols. Aminohydrazides, hydroxyhydrazides, semicarbazide hydrazides or water) in one or more stage processes in the melt or in solvents after a A large number of known and modifiable processes are produced.

Examples of starting materials are: polyesters made from adipic acid and dialcohol from 2 to about 10 carbon atoms, preferably those with more than 5 carbon atoms, the dialcohols it is also possible to use a mixture to lower the melting points of the polyesters: polyesters from caprolactone and dialcohols, also polyalkylene ether diols, especially polytetramethylene ether diols. Polytrimethylene ether diols, polypropylene glycol or corresponding copolyethers. As diisocyanates aromatic diisocyanates such as diphenylmethane-4,4'-diisocyanate or tolylene isocyanate are preferred. araliphatic, such as m-xylylene diisocyanate, or aliphatic diisocyanates, such as hexamethylene diisocyanate or dicyclohexylmethane ^^ '- diisocyanate. used. The chain lengthening agent used is water. Di- or tri-alcohols. like butaneciol and / or p-xylylene glycols or trimethyloipropane. Diamines, such as diphenyl methane-4.4'-diamine, 3.3'-dichloro-diphenylmethane-4,4'-diamine. however, preference is given to aliphatic diamines such as ethylenediamine. Isophoronediamine. meta-xylylenediamine. as Hydrazine or dihydrazides. such as carbodihydrazide. Oxalic acid dihydrazide. Malonic acid dihydrazide or Terephthalic acid dihydride, or semicarbazide hydrazides, such as / i-semicarbazido vinyl hydrazide. to use.

Polyurethanes are preferably stabilized, which

In addition to urethane groups, they also have —NH — CO — NH groups and an essentially linear, segmented molecular structure formed _{by the reaction of isocyanate groups with water or —NH 2 terminal groups (e.g. diamines, dihydrazides, carbodihydrazide or hydrazine)} highly polar solvents, such as dimethylformamide or DimeJ.hylacetamid, are soluble and their characteristic segments can be characterized by the following formula excerpt:

—R — NH — CO — 0 — G — 0 — C — NH-R — NH-CO —HN-X — NH-CO — NH—

Herein, R is a divalent aliphatic, araliphatic or aromatic residue (of a diisocyanate), G is the residue of a higher molecular weight PoIyhydroxylverbindung a molecular weight of 500 to 5,000, and melting points below 60 ⁰ C without its terminal hydroxyl groups (eg. B. radical of a PoIyalkylenäthers, polyester, polyacetal or Poly-N-alkyl urethane) and X is the residue of a divalent chain extender with terminal NH ₂ groups without the terminal NH ₂ groups, e.g. B. an aliphatic, araliphatic, aromatic or heterocyclic radical

- NH-CO-alkylene-CO — NH radical

-NH-CO-NH- (CHj) ₂ -CO-NH-ReSt

or a bond between two N atoms. The synthesis of such polyurethanes (ureas) is extensive in the German Auslegeschrift 12 70 276 described. Polyurethane foams can, for. B. with the addition of the stabilizers to the starting components (e.g. polyethers) by known processes and recipes (see, for example, Kunststoff-Handbuch, Vol. VII. Polyurethane. Carl Hanser Verlag Munich. 1966, pp. 440 to 457, 504 to 531).

The stabilizers can be used with the polyurethanes in any manner more adapted to the process engineering requirements Manner dissolved stabilizers to solutions of the polyurethanes, z. B. to those for spinning, coating or coagulation purposes, preferred solutions in highly polar solvents, e.g. B. dimethylformamide or dimethyl sulfoxide. With the help of suitable mixing devices, such as kneaders or rollers, you can however, the stabilizers can also be incorporated into the melts or plasticized polyurethane sheets. Elastomer threads can optionally also be added to the stabilizers together with the preparation Get applied to the surface.

Another option is to use the stabilizers already add to the starting materials for polyurethane production and only with these the Carry out polyurethane synthesis. So are the alkoxy-substituted ones Compounds in the higher molecular weight polyhydroxy compounds (e.g. polyesters or polyethers) soluble. With such stabilizer-containing polyesters or polyethers can then corresponding polyurethane syntheses, e.g. B. Production of foams or elastomers carried out will. Also the diisocyanates or from higher molecular weight polyhydroxy compounds and NCO pre-adducts formed from (excess molar amounts) diisocyanates can be used as stabilizers be added before the formation of the polyurethane z. B. by spinning in aqueous diamine solutions he follows. By using the stabilizers in the conversion of NCO pre-adducts with chain extenders such as diamines, hydrazine, hydrazides or similar chain extenders In highly polar solvents such as dimethylformamide or dimethylacetamide, the polyurethanes can already be discolored prevent during their synthesis. The amount of stabilizers added is 0.05 to 10 percent by weight, preferably 0.2 to 3.0 percent by weight, based on the solid polyurethane substance.

By adding the stabilizers used as claimed to polyurethanes which contain reaction components with tertiary, aliphatically substituted amino groups in amounts of 0.02 to 1 mol, preferably 0.05 to 0.3 mol per kilogram of elastomer substance, a further increase in the light protection effect is observed. Examples of such reaction components are glycols and diamines. To name dihydrazides or polyesters or polyethers with tertiary amino groups, z. BNN-bis- {ß -hydroxypropyl) -methylamine, N, N'-bis- (fi -hydroxyethyl) -piperazine. N, N'-dimethyl, N.N'-bis - (- / - aminopropyl) ethylenediamine, N, N'-bis -> - aminopropyl) piperazine or polyethers containing tert-amino groups or tert-amino groups Polyesters which have been produced using dialcohols containing tertiary amino groups.

Preparation of the alkoxy-substituted, sterically
hindered phenols

A 2-tert-alkyl-4-alkylphenol is in the presence of catalytic amounts of a strong acid such as

z. B. p-toluenesulfonic acid, phosphoric acid, sulfuric acid, hydrochloric acid or a strongly acidic ion exchanger with an alkoxybenzene which has 1 or 2 hydroxymethyl groups in the o-position to the alkoxy radical contains, condensed in an organic solvent. The water resulting from the condensation can optionally be removed by azeotropic distillation. As a solvent, for. B. Benzene, toluene, petroleum ether, cyclohexane, methanol, ethanol, glacial acetic acid, dioxane or chlorinated hydrocarbons, such as chloroform or ethylene chloride can be used.

A preferred general embodiment of the condensation is described below:
The mixture of a 2-tert-alkylphenol and an o-hydroxymethylalkoxybenzene is in the presence of catalytic amounts of a strong acid, such as. B. p-toluenesulfonic acid. in a water-immiscible organic solvent, such as. B. toluene, heated to boiling on a water separator until

& S the elimination of water has ended. The hydroxymethyl compound can optionally be in solid form, as a solution or as a melt in small portions within a longer period of time into the

609 518/472

boiling reaction mixture are entered. The reaction product generally falls on cooling in crystalline form and is worked up as usual (filtration; recrystallization).

The alkoxybenzenes with 1 or 2 hydroxymethyl groups are known or can be used analogously Process are produced.

Preparation of 4-methyl-2,6-bis- (2'-hydroxy-3'-tert-butyl-5'-methylbenzyl) anisole

(Stabilizer A)

A solution of 200 g (1.22 mol) of 2-tert-butylp-cresol and 1 g of p-toluenesulfonic acid in 500 ml of toluene is heated to the boil using a water separator. Within 6 hours, then allowing 4-methyl-2,6-benzenedimethanol xy dripped slowly into 150 ml of toluene an heated to 100 ⁰ C solution of 100 g (0.55 mol) of 1-meth ©. The mixture is heated for another 3 hours to boiling, then at about 8O ⁰ C 1.3 1 light petroleum added, the solution is cooled and sucks

Table 1

after a few hours, the precipitated crystals stand out.

88 g are obtained

-CH,

(Stabilizer A)

in the form of colorless crystals, m.p. 188 to 19O ⁰ C.

Concentration of the filtrate gives a further 24 g of melting point 188 to 189 ° C.

The substances listed in Table 1 below were given after the implementation of the specified Starting substances in the appropriate Molver ratios prepared in an analogous procedure.

stabilizer

Starting product molar ratio

Fp. (Q of the stabilizers

OH

OCH,

OH

194 to

OH

OCH

(M.p. 88-89 "C)
OCH ₃

1: 1

119 to 120

OH

OCH

CH ₃
(Bp. 145-147 ° C / 14 Torr)

H ₂ -OH 1: 1

(Mp. 104-106 ⁰ C)
OCH,

2: 1

172

226

tert-butyl.
tert-octyl.

OCH ₃

(M.p. 162-163 ° C)

example 1

800 parts of a polytetramethylene ether diol (molecular weight 1010), 17.4 parts of NN-bis (/ <- hydroxypropyl) -N-methylamine, 306.6 parts of diphenylmethane-4,4'-diisocyanate and 284 parts of chlorobenzene are 65 to 52 minutes 70 ⁰ C heated and then cooled to room temperature. 400 parts of this NCO pre-adduct solution (1.88% NCO) are introduced within 4 minutes into a fresh suspension, prepared by adding 15 parts of solid carbonic acid to a solution of 5.93 parts of ethylenediamine in 898 parts of dimethylformamide, with thorough stirring. a homogeneous, viscous, pale yellowish solution is formed. This solution is pigmented by adding 4 percent by weight (based on solid substance) of titanium dioxide (rutile).

The solution (viscosity 423 P) is in proportions with or without added stabilizer in the usual way in Foils transferred, cut into threads and irradiated as such with UV light (fade-o-meter) (see table 2).

In a similar reaction as in the above example, the 2 percent by weight of stabilizer A (6.52 parts) not added to the finished solution afterwards (see above), but together with the

ίο Ethylenediamine dissolved in dimethylformamide and then the solution prepared with the NCO pre-adduct. It became a homogeneous, viscous, perfect colorless solution obtained, which did not discolor even when exposed to air. After shedding to movies and

is exposure of the threads was practically identical stabilizing effect against strength degradation measured under exposure.

Table 2

stabilizer

Before the exposure university! Fade-o-meter exposure

22 hours 44 hours 66 hours 88 hours

RF expansion RF expansion RF expansion RF expansion RF

(g, den) (%) (g / den) (%) (g / den) 1%) (g / den) (%) (g.'den) (%)

strain

Without stabilizer additives

+ 2% stabilizer A

0.60 584
Discoloration:
almost colorless

0.60 585

Discoloration:

colorless

<0.03 <100 yellow

0.60
colorless

586 not measurable
yellow-brown

0.59 587
almost colorless

yellow-brown

0.58 580
almost colorless

yellow-brown

0.18 330
pale yellowish

Example 2

500 parts of a mixed polyester (molecular weight 1660) of adipic acid and the diol mixture of 1,6-hexanediol and 2,2-dimethylpropanediol in a molar ratio of 65:35 are after 1 hour dehydration at 130 ^c C / 10 Torr at 55 ° C with 129 parts of N, N- Bis - (/? - hydroxypropyl) -N-methylamine and 1782 parts of diphenylmethane-4,4'-diisocyanate are added and the mixture is heated in a boiling water bath (about 70 minutes) until the NCO content of the NCO pre-adduct melt is 2.22%.

In an approximately 80 ^° C. solution of 297.5 parts / i-semicarbazidoalanyl hydrazide

(H ₂ N NHCONHCH ₂ - CH ₂ ■ CO - NH · NH ₂ )

820 g of a 33% strength titanium dioxide paste are introduced into 18,813 parts of dimethylformamide, and then 6,460 parts of the NCO pre-adduct melt are stirred in, a highly viscous solution (615 P / 20 ° C.) being formed.
According to the invention, the solution is partially mixed with various stabilizers or with comparison substances and partially exposed in the form of elastomer films in the fade-o-meter (see Table 3) or, after spinning to form elastomer threads, exposed in the fade-o-meter Threads determined (see Table 4). The spinning took place after the dry spinning process by extrusion of the solution through a nozzle with 16 bores of 0.2 mm diameter in a heated shaft (220 to 230 ° C) and pulling off the threads at a speed of about 100 m / min and winding up at about 130 m / min. The threads (total titre about 190 denier) were then tempered for 1 hour at 130.degree.

Table 3

stabilizer Discoloration after Fade-o-meter exposure from 1440 minutes 480 minutes 900 minutes yellow-brown Without addition almost colorless yellow-brown yellow 2% stabilizer almost colorless yellowish DT-AS 1243 866 colorless 0.5% stabilizer A colorless colorless colorless 2% stabilizer A colorless colorless almost colorless 2% stabilizer B colorless colorless

continuation

stabilizer

Discoloration after relade-n-metci exposure 4SI) minutes 4 (K) minutes

1440 minutes

2% stabilizer C colorless

2% stabilizer D colorless

2% stabilizer E colorless

colorless colorless colorless almost colorless
almost colorless
yellowish

Comparative experiments with a stabilizer which reveals a cycloalkyl radical in place of the tertiary alkyl radicals (Compound F)

2% compound F.

almost colorless

OH

CH,

yellowish
OCH ₃ OH

intense yellow

CH, CH ₁ CH,
(M.p. 156-157 ° C).

The results listed in the table are substituted for those used according to the invention

it can be seen that the stabilizers used according to the invention the tertiary alkyl radical by z. B. a

alkoxy-substituted. sterically hindered phenols cyclohexyl radical, the discoloration-free, sta-

have a very good stabilizing effect, which again reduces the bilising effect in polyurethanes

exceeds the effect of known good stabilizers. loren.

Table 4

Decrease in strength of elastomer threads (individual titre about 12 denier) after fade-o-meter exposure

900 minutes

1440 minutes

Before exposure 480 minutes

Tear Break Tear Break Tear Break Tear Break strength elongation strength elongation strength elongation strength elongation

(g denl (%) (g denl (% l (g den) (%) (g / den) (% l

Without stabilizer

2% stabilizer A

2% stabilizer A. but threads

Washed for 3 hours *)

2% stabilizer

DT-AS 12 43 866

* Treated for> 3 hours in a solution of 5 g / l soap + 2 g / l soda at 60 ° C.

0.54 400 0.41 350 0.12 175 - - 0.55 370 0.50 350 0.42 340 0.33 330 0.55 400 0.51 370 0.46 385 0.30 300 0.55 400 0.47 400 0.33 335 0.14 <300

Example 3

1000 parts of a polytetramethylene ether diol (OH - Z ■ 111), 20.6 parts of NN-bis (/ f-hydroxypropyl) -N-methylamine, 369 parts of diphenylmethane-4,4'-diisocyanate and 349 parts of chlorobenzene are 65 to 50 minutes 70 ^c C heated to form the NCO pre-adduct. After subsequent cooling, the NCO content is 1.69%.

5.27 parts of ethylenediamine are dissolved in 895 g of DMF, 13 parts of finely divided pigments (rutile) and then 15 parts of solid carbonic acid are added. 400 parts of the NCO pre-adduct solution are stirred into this suspension in a few minutes, a solution at 565 P / 20 ° C. being formed. Portions of the solution were each mixed with 2% of stabilizer / or B as well as corresponding known comparison substances with free hydroxyl group in place of de methoxy radical. Films were produced in known manner from portions of the solution without or with the addition of stabilizer and these in fade-o-mete exposed (see Table 5).

The results show that the stabilizers used according to the invention are far superior; they do not result in discoloration on exposure The known compounds can also delay de strength degradation somewhat, untei are, however, a strong discoloration and are therefore for colorless articles such as foils or threads not suitable.

15th

Table 5

Without stabilizer

OH

OCH,

OH

CH ₃ CH ₃

(Stabilizer A)

OH OH

CH, -f X

CH ₃ CH ₃

(Comparison substance)

OCH ₃

CH

CH ₃ OH

CH ₃

CH ₃ CH ₃

(Stabilizer C)

CH, -

(Stabilizer B)

Properties of the films after 22 hours of fade-o-meter exposure

Foils discolored yellow Strength completely degraded

Colorless foils

Maintain strength

Foils yellow-brown

Strength largely
obtain

Foils colorless

Maintain strength

Foils intensely yellow to largely firm
received yellow-brown

Colorless foils

Maintain strength

Example 4

800 parts of a polytetramethylene ether diol (OH Z 111) are mixed with 17.4 parts of N, N-bis (/ i-hydroxypropyl) -N-methylamine, 306.6 parts of diphenylmethane-4,4'-diisocyanate and 284 parts of chlorobenzene for 50 minutes heated to 65 to 70 ⁰ C and then cooled to room temperature.

800 parts of the NCO pre-adduct solution obtained (1.9% NCO) are stirred with a solution of 38.7 parts of 4,4'-diaminodiphenylmethane in 1872 parts of dimethylformamide and, after 12 hours, with 3.38 parts of diphenylmethane-4, 4'-dii: 5ocyanate added, a viscous solution (102 P / 20 ^c C) being obtained which contains 1 part of acetic anhydride per 100 parts

609 518/472

Solution is added. The solution is made by adding 4% titanium dioxide (rutile) - based on aut Solid elastomer substance - pigmented.

Proportions of the above solution are 2% of the inventive Stabilizer A used is added.

The solutions with or without a stabilizer can be used

painted on glass plates and at 100 "C / 60 minutes dried. The approximately 0.15 to 0.20 mm thick elastomer films are cut using a film cutting machine cut into threads of about 300 the thread size and then 0, 22, 66 hours in irradiated with UV light using an ATLAS fade-o-meter.

Table 6

Fade-o-meter exposure (in hours)

stabilizer

Without stabilizer additives

2% stabilizer A

Before exposure 22 hours

Tear strength Elongation at break Tear strength (g / den) (%) ⁽ 8 ^{/ den)}

44 hours

Elongation at break tear strength wedge
(%) (g / den)

Elongation at break

0.65 600

Discoloration: almost colorless

0.66 605

Discoloration: colorless

<0.05 yellow-brown

0.60 colorless 142

620

no longer measurable
yellow-brown

0.53
colorless

621

Example 5

800 parts of a polytetramethylene ether diol <OH-Z-Hl) are mixed with 18.0 parts of N, N-Bis- | ^ -hydroxypropyl) -N-methylamine, 394.5 parts of diphenylmethane-4,4'-diisocyanate and 304 parts of chlorobenzene heated to 80 ° C for 40 minutes, an NCO pre-adduct formed, which after cooling to Room temperature contained 3.58% NCO.

Solution 1

404 parts of the NCO pre-adduct solution are mixed with 3.30 parts of water in 889 parts of dimethylformamide stirred at room temperature, the solution hach turning yellow for about an hour and afterwards 24 hours results in a highly viscous and strongly yellow-colored solution. When the solution is spun the usual dry spinning process gives yellow-colored elastomer threads.

Solution Il

404 parts of the NCO pre-adduct solution are stirred with 3.30 parts of water and 6.4 parts of stabilizer A (2 percent by weight) in 890 parts of dimethylformamide at room temperature, a highly viscous, completely colorless solution being obtained after 24 hours, which after spinning conventional dry spinning process results in colorless elastomer threads which, even when exposed to light or when treated with hot air, have a significantly better stability against discoloration or strength degradation than the threads from solution 1.

The solution I is mixed with 2 percent by weight

3 °

35

40

45 Stabilizer A, weakly colored elastomer threads are obtained which, upon exposure to light or hot air treatment (e.g. 1 h / 150 ° C) are much more stable than threads from solution I without the addition of a stabilizer.

Example 6

800 parts of polytetramethylene ether diol, molecular weight 1010 are mixed with 17.35 parts of N, N-bis (/ i-hydroxypropvO-methylamine, 326.5 parts of diphenylmethane-4 4'-diisocyanate and 287 parts of chlorobenzene for 40 minutes at 70 ^° C. to form the A highly viscous (600 P) solution is obtained by stirring 408 parts of the pre-adduct into a hot solution of 10.7 parts of carbodihydrazide in 960 parts of dimethylformamide at about 60.degree. C. This solution contains 1 percent by weight of the stabilizer A (based on solid substance) added, partly left without stabilizer. Films obtained from the solutions show the following values after fade-o-meter exposure:

Table 7

5 °

55 tensile strength (in g / den)
Fade-o-meter exposure
(in hours)

22nd

44

66

Without addition

+ 1% stabilizer A

0.68 0.27 no more

measurable
0.68 0.69 0.48 0.30

Claims (1)

Patent claims: 1. Process for the stabilization of polyurethane elastomers by sterically hindered phenols, characterized in that alkoxy-substituted, sterically hindered phenols the formula OH OR