DE2065975C3 - Stabilizing polyurethanes against degradation and discoloration - Google Patents

Description

in which R is a straight-chain or branched Q- to Ci8-alkyl radical, an unsubstituted or through lower alkyl radicals substituted Cs to Ce cycloalkyl radical or a C7- to Cg-aralkyl radical, and

b) a 2- (2'-hydroxyphenyl) benzotriazole of the general formula

25th

HO

JO

in the

X is hydrogen, an alkyl radical or halogen, Y is hydrogen, a Ci- to Ciralkyl radical or

an alkylene radical with heteroatoms, R 'is hydrogen or a C _t - to Cir alkyl radical

mean, in amounts of 0.05 to 5.0 wt .-%, based on the polyurethanes, the weight ratio of a to b being 10: 1 to 1:10, for Stabilization of optionally foamed polyurethanes against degradation and discoloration during the Exposure to light through addition before, during or after the manufacture of the polyurethanes.

40 Elastomers, coatings, foils or elastomer threads are widely used, are - depending on their structural components - against the action of light, but ζ, Τ, also in air at higher temperatures, are unstable and their strength values are thereby degraded, whereby in In many cases, severe discoloration of the polyurethanes also occurs

Many efforts have been made by adding known antioxidants such. B. phenol-based, a To achieve protection against discoloration and degradation, but this stabilization is generally not sufficient.

For example, phenols such as 4,4'-alkylidene-bis- (6-tert-butyl) -m-cresol, 2,6-di-tert-butyl-4-methylphenol or 4,4'-methylene-bis (2,6-di-tert-butylphenol), tested as stabilizers, but these show either a troublesome initial discoloration or failure protection against discoloration when exposed to light or atmospheric agents. Furthermore, polyphenols, such as 1,3,5-trimethyl-2,4,6-tris- (3,5-di-tert-butyl-4-hydroxybenzyl) -benzoI, Tried as stabilizers (DE-AS 12 43 866). Furthermore, a number of phenolic compounds have been named, which are common with hydroxybenzophenones are said to be suitable for stabilizing polyurethanes (DE-AS 11 06 490). The effect of these phenolic stabilizers however, it is not sufficient. They are not washable and have an inherent color that z. B. for white elastomer thread is unsustainable

A new class of phenolic stabilizers has now been found which, due to their typical Structure enables a highly effective stabilization of polyurethanes, these stabilizers are colorless, do not cause discoloration in polyurethanes and offer significantly improved protection against Discoloration and degradation when exposed to visible and / or UV light and / or atmospheric agents (such as Cause oxygen, nitrogen oxide or combustion exhaust gases). The substances are also in the polyurethanes easily soluble and does not crystallize on the surface.

The invention relates to the use of a mixture of

2. Use of a mixture according to claim 1, according to which the bisphenols are those of the general formula

^r .o

a) bisphenols of the general formula

OH

in the R a straight-chain or branched Ci- bis

in which R denotes a methyl, t-butyl, cyclopentyl or Cir-alkyl radical, an unsubstituted or lower cyclohexyl radical, C ₅ - to Ce cycloalkyl radical or alkyl radicals

be used. 6o denotes a C7 to Ce alkyl radical, and

b) a 2- (2'-hydroxyphenyl) -bcnztriazole of the general

my formula

R '

Polyurethanes, which are made from higher molecular weight polyhydroxyl compounds, Polyisocyanates and chain extenders in the form of foams,

in the

X hydrogen, ACyl radical or halogen, Y is hydrogen, a C _r to Qr alkyl radical or a

Alkylene radical with Heteroatonjen, R 'hydrogen or a C ₁ - to Cir-alkyl radical

mean, in amounts of 0.05 to 5.0% by weight, based on the polyurethanes, the weight ratio of a to b 10; 1 to 1:10 to stabilize optionally foamed polyurethanes against degradation and discoloration when exposed to light by adding before, during or after the production of the polyurethanes.

Examples of radicals R for the compound of the formula (I) are:

Methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl-, tert-butyl-, amyl-, isoamyl-, hexyl-, Isohexyl, isooctyl or isononyl radicals, cydopentyl, cyclohexyl, 4-methylcyclohexyl, «-Methyicyciohexylreste or benzyl, α-MethyIbenzyl- or «A-dimethylbenzyl radicals.

The bisphenols of the general formula are preferred

OH

in which R is a methyl, t-butyl, cydopentyl or Cyclohexyl radical means for use.

The following stabilizers are particularly preferably used

50

OH

CH ₁ ? "

CH ₃ (V)

10

! 5

20th

25 The oA'-bis- (2-hydroxyphenyl) -l, 4-diisopropylbenzenes, which are also referred to below as bisphenols for short, are new compounds and can be converted into a ^ a'-dihydroxy-1,4- düsopropyIbenzol with ortho-substituted 4-methylphenols with elimination of water in the presence of acidic dehydration catalysts, z. B. according to the following reaction equation:

OH

OH

OH

30th

R + 2H ₂ O

in which formula R has the meaning already given for formula I.

The essential improvement that can be achieved by using the new bisphenols together with the benzotriazoles is shown in comparative tests compared to a commercially available mononuclear phenol, 2,6-di-tert-butyl-p-cresol, a binuclear phenol, methylene-bis- (2-hydroxy-3-tert-butyl-5-methylphenol, and a trinuclear phenol, 13,5-trimethyl-2,4,6-tris- (3,5-di-tert-buty] -4-hydroxybenzyl) -benzene (X) shown in 2 further examples in which a bisphenol (VI) which is unsubstituted in the ortho positions and also a bisphenol with OH groups in the p-position (VII) (as described in BE-PS 6 04 516) ) were used, the strict dependency on the effect and constitution of the B ^: sphenols is shown.

OH

HO

CH3 (Vl)

Here shows, among other things, that similarly constructed, many of -C (CH 3) only comprise phenols as stabilizers used which, however, instead of 2-grouping a -CHrGruppierung between the benzene nuclei, such as _T bis- or trisphenols such as

OH

OH _CH

CH ₂ - ^ pC-CH ₃

CH ₃

or

CH ₃
(VIII)

OH

OH

OH

(CH ₃ J ₃ C

C (CH ₃ ),

(IX)

10

15th

20 The use of 2- (2'-hydroxyphenyl) -b "nztriazolen as stabilizing additives in polymers is known, but it is quite insufficient as the sole stabilizer. Also a combination of 2- (2'-hydroxyphenyl) -benztriazo | enes and 1,3,5-trimethyl-2,4,6-tris- (3,5-ditertiary * rbutyl-4-hydroxybenzyl) -benzo | or £ 4 £ -Tetramethyl-3,6-bis- (3 £ -ditertiarbutyl-4-hy-

droxybenzyl) benzo | is used to stabilize segmen oriented polyurethanes in NL-AS 65 09 745 described. These additives show a certain, but not sufficient, protective effect and it remains that There is a need for a highly effective, permanent stabilization of elastomers, especially elastomer threads.

Benztriazoles of the following formula are preferably used as compound (b)

HO

compared to the stabilizer mixtures used according to the invention when exposed to UV light show a strong self-discoloration (yellow) and thus for stabilization colorless polyurethanes are unsuitable. In addition, the bisphenols show better stabilization against degradation as z. B. the well-known phenolic stabilizer 13 ^ -trimethyl-2,4,6-tris- (4-hydroxy-3,5-di-tert-butylbenzyl) -benzene (according to DE-AS 12 43 866). With relatively little modification of the structure of the phenols, e.g. B. Shifting the alkyl radicals, significantly lower stabilization effects or z. T. also yellow discoloration observed (see comparative experiments).

The stabilization according to the invention, which is so significantly effective for polyurethane elastomers, was surprising and not foreseen.

Surprisingly, the effectiveness of the phenols is not due to the presence of a tertiary alkyl radical restricted in the o-position to the hydroxyl group and there are compounds with secondary or primary Alkyl radical also effective.

The following formula is used as 2- (2'-hydroxyphenyl) benzotriazoles:

(Π)

HO

Here, X denotes hydrogen, alkyl radicals, halogen, Y denotes hydrogen, a Ci- to C ^ -alkyl radical or an alkylene radical with heteroatoms, preferably a tert-alkyl radical, e.g. B. tert-butyl, tert-Amy !, tert-dodecyl, R _{f is} hydrogen or a Ci- to Ci2-alkyl radical, e.g. B. methyl, ethyl, iso-propyl, tert-butyl, tert-amyl, tert-octyi or tert-dodecyl radical.

The mixture is used in a weight ratio of compounds a) and b) of 1:10 to 10: 1, whereby the polyurethanes provide a synergistically effective stabilization against discoloration and degradation upon exposure experience of light, warmth and atmospheres.

X hydrogen or chlorine,

Y is hydrogen or a Ci- to Cir-alkyl radical, preferably tert-alkyl, e.g. B. terL-butyl-, terL-amyl-, or a - N-methylenphthalimido radical and

T is hydrogen or a Ci to C | _2- alkyl radical, e.g. B. methyl, ethyl, isopropyl, terL-butyl or tert-amyl radical

represent.

As a light stabilizer based on 2- (2'-hydroxyphenyl) benzotriazole the following connections are to be named, for example:

2- (2'-Hydroxy-5'-methylphenyl) -benztriazole, 2- (2'-Hydroxy-5'-methylphenyl) -5 chlorine

bcnztriazole,
2- (2'-Hydroxy-3'-tert-butyl-5-methylphenyl) -

benzotriazole,
2- (2'-Hydroxy-3'-terL-buty! -5-methylphenyl) -

5-chlorobenzotriazole,
2- (2'-Hydroxy-3'-methyl-5-tert-butylphenyl) -

benzotriazole,
2- (2'-Hydroxy-3'-methyl-5-tert-butylphenyl) -5-chlorobenzotriazole,

2- (2'-Hydroxy-3 ', 5'-dimethylphenyl) -benztriazole, 2- (2'-Hydroxy-3 \ 5'-dimethylphenyl) -5-chloro-

benzotriazole,
2- (2'-Hydroxy-3 ', 5'-di-tert.-butylphenyl) -benztriazole,

2- (2'-Hydroxy-3 ', 5'-di-tert-butylphenyl) -5-chlorobenzotriazole,

2- (2'-Hydroxy-3 ', 5'-di-terL-amyIphenyl) -

benzotriazole,
2- (2'-Hydroxy-3 ', 5'-di-tert-amylphenyl) -5-chlorobenzotriazole,
2- (2'-Hyc ^! .Oxy-3 ', 5'-di-tert.-octylphenyl) -

benzotriazole,
2- (2'-Hydroxy-3 ', 5'-di-tert.-octyiphenylV5-chlorobenzotriazole or

2- (2'-Hydroxy-3'-N-methylenephthalimido) benzotriazole.

Further suitable hydroxyphenylbenzotriazoles are described in DE-AS 12 13 408, 12 13 409, for example.

12 13410, or in US-PS 32 13 058 listed. Acquaintance Polyurethane stabilizers (cf., for example, DE-AS 11 57 386) can also be used.

The elastic polyurethanes to be stabilized, which are optionally present in foamed form, can be produced by known processes and from the 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, melt products preferably below 60 ° C) and aliphatic, araliphatic or aromatic polyisocyanates (preferably aromatic diisocyanates, such as Tolylene diisocyanate or diphenylmethane-4,4'-diisocyanate). as well as so-called chain extenders, ie low molecular weight compounds (molar weight z. B. 18 to 400) with two or more isocyanate-reactive groups Ϊ7 R Wa ^ sc ", low molecular weight diols, diamines, dihydrazides or similar compounds, such as B. Amino alcohols, amino hydrazides, hydroxy hydrazides, aminosemicarbazides, semicarbazide hydrazides, semicarbazidocarbazine esters or corresponding mixtures of these chain extenders in single or multi-stage processes in melt or in solvents 2> by a large number of known and modifiable processes.

Examples of starting materials are: polyesters made from adipic acid and dialcohols having 2 to about 10 carbon atoms, preferably those having more than 5 carbon atoms, the dialcohols also being able to be used as a mixture to lower the melting points of the polyesters; Polyesters made from caprolactone and dialcohols, also polyalkylene ether diols, especially polytetramethylene ether diols, polytrimethylene y, ether diols, polypropylene glycol or corresponding copolyethers. Preferred diisocyanates are aromatic diisocyanates such as diphenylmethane 4,4'-diisocyanate or tolylene diisocyanate, araliphatic ones such as m-xylylene diisocyanate, or aliphatic diisocyanates such as hexamethylene diisocyanate. or dicyclohexylmethane-4,4'-diisocyanate. used. These starting materials are converted - if necessary with additionally used dialcohols - to NCO pre-adducts, which preferably have the structures given in Belgian patent 734194. The chain extenders used - optionally as a mixture or in stepwise reaction - are water and / or di- or tri-alcohols, such as butanediol. p-xylylene glycols, trimethylol- vi propane. Amino alcohols, such as ethanolamine, diamines, such as diphenylmethane-4,4'-diamine or 3,3'-dichloro-diphenyimethane-4,4'-diamine, but preferably aliphatic diamines, such as ethylenediamine, 1,2-propylenediamine, isophoronediamine or meta-xylylenediamine, as well as hydrazine or dihydrazides, such as carbodihydrazide, oxalic acid dihydrazide, glutaric acid dihydrazide, pimelic acid dihydrazide or terephthalic acid dihydrazide, or semicarbazide hydrazides, such as / J-semicarbazidalanyl hydrazide, optionally as a mixture of the chain extension means for use.

Polyurethanes are preferably stabilized which, in addition to urethane groups, also by reaction of Isocyanate groups with compounds containing water and / or NH2 end groups (e.g. diamines, dihydrazides, Carbodihydrazide, semicarbazide hydrazide or hydrazine) - NH-CO-NH groups and have an essentially linear, segmented molecular structure, in highly polar solvents, such as dimethylformamide or dimethylacetamide are soluble before they are shaped and their characteristic Segments can be characterized by the following formula excerpt:

-E-Y ■ NH · CO · NH · X · NH · CO · NHf-

this segment from the implementation of an NCO pre-adduct OCN · Y · NCO with a chain extension agent H ₂ N · X · NH _{2 may have} arisen. B. wi «be structured as follows:

-R · NH · CO · O ■ D · O ■ CO · NH · R-

or others. üblirhp ZiisammenKet7! incrpn aiifwpispn (see Belgian patent 7 34 194).

Here, R denotes a divalent aliphatic, araliphatic or aromatic radical (of a diisocyanate), D the radical of a higher molecular weight polyhydroxyl compound with a molecular weight of 500 to 5000 and melting points below 6O ⁰ C without their terminal hydroxyl groups (e.g. radical of a polyalkylene ether, polyester, polyacetal or Poly-N-alkyl urethane). X ^; rt the remainder of a divalent chain extender with terminal NH ₂ groups without the terminal NHj groups, e.g. B.

an aliphatic, araliphatic, aromatic or heterocyclic radical,

a - HN-CO-alkylene-CO-NH radical,

a -NH-CO-NH- (CHj) ₂ -CO-NH-ReSt

or

a bond between two N atoms.

The synthesis of such polyurethane (ureas) is detailed e.g. in DE-AS 12 70 276 and in BE-PS 7 34 194 described. Polyurethane foams can, for. B. with the addition of stabilizers to the Starting components (e.g. foly ether) according to known processes and recipes (see e.g. plastics manual, Volume VII, Polyurethane, Carl Hanser Verlag Munich, 1966. Pages 440 to 457, 504 to 531) will.

The stabilizer mixtures can be used with the polyurethanes in any process-related aspects be incorporated in an adapted manner. The simplest dosage is when adding ^? Γ optionally dissolved stabilizers to form solutions of the polyurethanes, e.g. 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, however, the stabilizers can also be incorporated into the melts or plasticized polyurethane sheets. Elastomer threads If necessary, the stabilizers can also be used together with the preparation on the surface of the Otter get applied.

Another option is to use the stabilizer mixtures to be added to the starting materials for polyurethane production and only with these to carry out the polyurethane syrups. So are the bisphenol compounds in the higher molecular weight polyhydroxy compounds (e.g. polyesters or poly

ether) soluble. With such stabilizer-containing polyesters or polyethers can then corresponding polyurethane syntheses, eg. B. Manufacture of foams or elastomers. Also the diisocyanates or from higher molecular weight poly- ·> hydroxyl compounds and (excess molar amounts) diisocyanates are NCO pre-adducts the stabilizers can be added before the formation of the polyurethane z. B. by spinning in aqueous diamine solutions, takes place. By using the stabilizers in the implementation of NCO pre-adducts with chain extenders such as diamines, hydrazine, hydrazides or the like Chain extenders in highly polar solvents such as dimethylformamide or dimethylacetamide, ι ■> discoloration of the polyurethanes can be prevented during their synthesis. The additional amount of the stabilizer mixture is 0.05 to 5.0 percent by weight, preferably 0.2 to 3.0 percent by weight.

By adding the stabilizer mixture to be used according to the invention to polyurethanes which 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 substance contained, a further amplification of the light-> "> protective effect observed. Examples of such reaction components are glycols, diamines and dihydrazides or polyesters or polyethers with tertiary amino groups, e.g. B.

in

N, N-bis - (/? - hydroxypropyl) -methylamine,
N, N'-bis - (/? - hydroxyethyl) piperazine,
N, N'-dimethyl-, N, N'-bis (y-aminopropyl) -ethylenediamine,

N, N'-bis-y-aminopropyl) piperazine or r,

polyethers containing tertiary amino groups or polyesters containing tertiary amino groups, which using dialcohols containing tertiary amino groups.

40

Preparation of the bisphenols of the general formula I.

of txjx'- dihydroxy 1,4-diisopropylbenzene with orthosubstituted 4-methylphenols with dehydration 4i device in the presence of acidic dehydration catalysts, such as. B. p-toluenesulfonic acid, phosphoric acid, sulfuric acid, hydrochloric acid or strongly acidic ion exchangers.

The water resulting from the condensation can> o optionally removed by azeotropic distillation. As a solvent, for. B. benzene, cyclohexane, White spirit, toluene, xylene and chlorinated hydrocarbons such as chloroform and carbon tetrachloride or tetrachlorethylene can be used.

Another method of making the bisphenols is to use (XA'-dihydroxy-1,4-diisopropylbenzene with 2 molecules of p-cresol with elimination of water according to the above procedure condense and then alkylate the free ortho positions with suitable olefins or carbinols, cycloalkylate or aralkylate.

Such processes are known as such and are also not the subject of the invention.

Rather, the following information is intended to provide a more detailed explanation of the preparation of the bisphenols as well as the two compounds VI and VH used for comparative experiments.

Λ, α'-bis (2-hydroxy-3,5-dimethylphenyl) -1,4-diisopropylbenzene
(Connection II on page 4)

220g (1.8 mol) 2,4-dimethylphenol, 97g (0.5 mol) «A'-dihydroxy-1,4-diisopropylbenzene and 500 ml of xylene were with the addition of 5 g of p-toluenesulfonic acid

Boiled for 1 hour on the water separator, 18 ml of water separating out. After cooling down, it became 500 ml of petroleum ether were added to the mixture, and the mixture was cooled to 5 ° C and sucked off the precipitated colorless crystals. These have a melting point of 178 to I79 "C on.

C ₂₈ HmO ₂ ; Molecular weight 402:

Calculated: C 83.58, H 8.46, O 7.96;
found: C 83.9, H 8.7, O 7.9.

1,4-diisopropylbenzene
(Compound III on page 4)

164 g (1 mol) of 2-tert-butyl-p-cresol, 49 g (0.25 mol) of Λ, α'-dihydroxy-1,4-diisopropylbenzene and 2.5 g of p-toluenesulphonic acid in 400 ml of mineral spirits were boiled for 1 hour on a water separator, with 9 ml of water farewell. To neutralize the catalyst were

Introduced 2 g of ammonia. The mixture was filtered and distilled to 100 ° C. in vacuo. A colorless powder precipitated out on addition of methanol. This was suctioned off and dried. Fp 105 ⁰ C.

O ₂ ; Molecular weight 486:

Calculated: C 83.95, H 9.47, O 6.58;
found: C 83.9, H 9.4, O6.0.

«, A'-bis (2-hydroxy-3-cyclopentyI-5-methylphenyl) -

1,4-diisopropylbenzene
(Compound IV on page 4)

352 g (2 mol) 2-cyclopentyl-p-cresol, 97 g (0.5 mol) Λ, α'-dihydroxy-1,4-diisopropylbenzene and 5 g of p-toluene sulfonic acid in 500 ml of mineral spirits were added for 2 hours

farewell. 2 g of ammonia were passed into the solution, filtered, and 500 ml of methanol were added. The precipitated crystals were recrystallized from toluene for further purification. Colorless crystals. Mp. 220 ⁰ C.

C ₃₀ H ₄₆ O ₂ ; Molecular weight 510:

Calculated: C 84.7, H 9.02, O 6.28;
found: C 83.9, H 9.1, O 6.3.

aA'-Qis- (2-hydroxy-3-cyclohexyl-5-methylphenyl) -

1,4-diisopropylbenzene
(Connection V on page 4)

380 g (2 mol) of 2-cyclohexyl-p-cresol, 97 g (0.5 mol) of Λ / x'-dihydroxy-i, 4-diisopropylbenzene and 5 g of p-toluenesulfonic acid in 600 ml of white spirit were boiled on a water separator for 1 hour , 18 ml of water separating out. At 50 ^° C., 2 g of ammonia were passed in. After filtering, 500 ml of methanol were added to the solution, colorless crystals separating out. Mp. 204 ⁰ C.

C ₃₈ H ₅₀ O ₂ ; Molecular weight 538:
Calculated: C 84.76, H 9.29, 0.5.95;
found: C 84.1, H 93.0 6.2.

<XA'-bis- (2-hydroxy-5-methylphenyl) -

1,4-diisopropylbenzene
(Connection Vl on page 6)

216 g (2 mol) of p-cresol, 97 g (0.5 mol), a'-dihydroxy-1,4-diisopropylbenzene, 5 g of p-toluenesulfonic acid and 500 ml of white spirit were boiled on a water separator for 1 hour, with 18 Separate ml of water. The product which had crystallized out was ^{filtered off with suction at 0 °} C. and recrystallized from benzene. Colorless crystals. Mp. 183 ° C.

example 1

2; Molecular weight 374:

Calculated: C 83.42, H 8.02, O 8.56;
found: C 83.7, H 8.0, 0 8.9.

<x, a'-bis (4-hydroxy-3,5-dimethyIphenyl) -

1,4-diisopropylbenzene
(Compound VII on page 6)

122 g (1 mole) of 2-hydroxy-1,3-dimethylbenzene, 49 g (0.25 mole) of «A'-dihydroxy-1,4-diisopropylbenzene, 2.5 g p-Toluenesulfonic acid and 300 ml of white spirit were boiled for 1 hour on a water separator, with 9 ml Separate water. 1 g of ammonia was passed into the hot solution. After filtering and cooling 250 ml of petroleum ether were added to the solution, the precipitated crystal slurry was filtered off with suction at 0 ° C, recrystallized from toluene. Colorless crystals. Mp. 160 ° C.

C28H34O2; Molecular weight 402:

Calculated: C 83.58, H 8.46, O 7.46;
found: C 83.6, H 8.6, O 8.2.

Table 1

500 parts of a polytetramethylene ether diol (molecular weight 1010), 104 parts of N, N-bis (j9-hydroxypro-

<> pyl) -N-methylamine, 1822 parts of diphenylmethane-4,4'-diisocyanate and 1740 parts of chlorobenzene are ^{heated to 60 to 68 °} C. for 68 minutes and then cooled to room temperature. 6450 parts of this NCO pre-adduct solution (2.05% NCO based on solids) are converted into a fresh suspension within 10 minutes, prepared by adding 75 parts of solid carbonic acid to a solution of 73.7 parts of ethylenediamine and 4.68 parts of 1 , 2-propylenediamine in 13,440 parts of dimethylformamide, with good stirring

n ren entered, resulting in a homogeneous, pale yellowish solution, the addition of 4% by weight (based on solid substance) titanium dioxide (rutile) is pigmented. The solution (viscosity 610 P) is in The usual proportions with or without the addition of stabilizers

2 »Transferred into foils, cut into threads and irradiated as such with UV light (fadeometer) (see table 2). Portions of these solutions were spun by the usual dry spinning process and the Threads with or without a stabilizer additive in a Xenotest exposure device irradiated (see Table 1). Do not add the 2% by weight stabilizer mixture afterwards added to the finished elastomer solution, but together with the diamines in dimethylformamide dissolved and then prepared the solution with the NCO pre-adduct, a colorless solution is obtained which does not change color when exposed to air. After potting into foils and exposing the threads, one became practical identical stabilizing effect against strength degradation measured under exposure.

Decrease in strength of elastomer threads after the dry spinning process (individual titer approx. 10 dtex total titer approx. 220 dtex) after Xenotest exposure

Before exposure

hours

145 hours

Remarks

REID- DrULIl- I \ CIU- DIULII- l \ ciu- Ui uv.ll-

strength elongation strength elongation strength elongation

g / dtex% g / dtex ° / o g / dtex%

Without stabilizer 0.59 506 0.17 372 no longer measurable only after more colorless yellowish yellowish-yellow than 200 hours 1% stabilizer II 0.61 500 0.40 480 yellowish colorless colorless colorless only after approx. 225 hours 2% stabilizer II 0.66 510 0.52 525 yellowish colorless colorless colorless synergistic B. effective Wed 133% stabilizer + 0.67% 0.66 510 0.63 510 0.60 512 schung; first m 2- (2'-hydroxy-3'-t-butyl- colorless colorless colorless after approx. 300 m 5'-methyl-phenyl) -benz- Hours yellow H triazole lich I.

Example 2

The bisphenols or comparative stabilizers given in Table rv are added to the solution (according to Example 1) redeemed in the specified amounts. After the solution has been poured and dried to form films Cut film strips and expose them in the fadeometer in the specified time

Table 2

Fadeometer exposure of film strips or cutting threads

Stabilizer additives

Before exposure

RF

g / dtex

% Dhg After fadeometer exposure of
h 44 h

RH% Dhg RH

g / dtex g / dtex

Dhg

66 h

RF

g / dtex

% Dhg

Without 0.56 f stabilizer colorless + 2% 0.72 e Stabilizer Il colorless 2% _ UV absorber *) colorless 1% 0.55 f Stabilizer Il 1% Tripnenyipliuspnii colorless 1% 0.46; Stabilizer Il 1% Triphenylphosphine colorless + 1.33% Stabilizer II 0.66% UV absorber *) colorless 2% ··) colorless Stabilizer III 2% ") colorless Stabilizer IV 2% ") colorless Stabilizer V Comparative tests: 2% colorless Compound VI 2% colorless Compound VII 2% colorless 1,3,5-trimethyl 2,4,6-tris (3,5-di- tertiary-butyl-4-hy- droxy-benzyl) -benzene (Connection X) 2% almost colorless Compound IX

657

651

613

590

<0.04 no longer measurable

yellow-brittle films, strong cracking when stretched

0.70 colorless

0.39

yellowish

0.50

laroios 0.43 652

525

620

630

almost colorless

0.62 662

(nearly)

colorless

no longer measurable

yellow

0.46 637

697

0.40

yellowish

038 653

almost colorless

0.41

tarbios 0.39

yellowish

615

678

··) colorless ") colorless ··) almost colorless ") colorless * ·) Almost colorless * ·) Pale yellow pale yellowish lich · *) Colorless · *) Almost colorless **) pale yellow pale yellowish lich ··) colorless · *) Almost colorless ") almost colorless pale yellowish pale yellow lich ·**) yellow * · *) Intense yellow ** ·) intense yellow (from 3 p.m.) **) yellow ... j "*) intense yellow (from 3 p.m.) intensive yellow "*) nearly *") yellow heavily built colorless intense yellow yellowish Strength relative well preserved yellow-brown strong yellow intense yellow

Exposure time strong cracking and significantly reduced tear strength.

As the results show, both in terms of maintaining mechanical strength and Reduction of discoloration by the stabilizer mixtures used according to the invention is a very good one Improvement achieved The use of phenyl phosphite or phosphine is not a significant one Improvement. The compounds VI and VII, which deviate only slightly from the structure of the components a) of the stabilizer mixture to be used according to the invention show an essential less favorable behavior due to strong discoloration and noticeably less protective effect. Known stabilizers, like compound IX or X, are also clearly inferior in their stabilization; either builds the polyurethane still degrades very strongly - or its strength is retained relatively well, however, discolors very strongly.

Claims (1)

Claims; 1. Use of a mixture of a) bisphenols of the general formula OH 10 IS