DE1151373B - Process for stabilizing homopolymers or copolymers of ª ‡ -olefins - Google Patents

Description

The action of oxygen or oxygen-containing Gases such as air, as well as the effect of light on polyolefins such as polyethylene, polypropylene, Polymethylbutene and polymethylpentene, in particular, lead at elevated temperature leads to a deterioration in the mechanical properties. This effect is caused by the breakdown of the polymer chain. The breakdown occurs both in solid and in the polymerization products present in dissolved form.

To prevent such degradation, there are numerous: Stabilizers available. Be like that z. B. proposed phenols with a molecular weight of at least 250 as stabilizers for polyethylene, also derivatives of 4,4'-dioxy-diphenylmethane, derivatives of dioxy-diphenyl-sulfide or pialkyl-mono- or dialkyl-disulfides, which in Combination with carbon black are very good heat stabilizers for polyethylene. All of these stabilizers but not satisfactory because they either do not cause sufficient resistance to oxidation because they discolor because they are incompatible with the polymer or because they "sweat out" over time.

It is also already known to prevent oxidation by adding a derivative of ethylene polymers To stabilize thiodipropionic acid. However, the effect of these stabilizers is not in many cases sufficient.

It has now been found that one had an excellent one Stabilization of homopolymers or copolymers of -olefins against oxygen, especially with higher temperatures, and against exposure to ultraviolet light, if you can as stabilizers, compounds of the general formula

R. OOC - R '- (S) _m - R' - COO · R

used, where R, when tn - 2, is an octadecyl radical, and when m = 3 or 4, an alkyl radical with at least 12 carbon atoms, an aryl or cycloalkyl radical and R 'represents aromatic or cycloalkylene radicals, hydrocarbon chains interrupted by heteroatoms or the group (CH ₂ ) n is where η is an integer between 1 and 20. The particular advantage of these compounds is that in their presence there is only a slight discoloration of the polymer under the influence of heat or light. For example, B. Derivatives of dioxy-diphenyl sulfide or -diphenyl disulfide, which were added as stabilizers to polypropylene, method for stabilizing homo-
or copolymers of α-olefins

Applicant:

Farbwerke Hoechst Aktiengesellschaft

formerly Master Lucius & Brüning,

Frankfurt / M., Brüningstr. 45

Dr. Claus Heuck, Hofheim (Taunus),
Dr. Otto Maiuz, Frankfurt / M.-Unterliederbach,
and Dr. Jakob Winter, Hofheim (Taunus),
have been named as inventors;

in the aging test at 140 ° C after about 14 days a strong tan. This undesirable discoloration occurred when the Di-, Trl · and Tetrasulfide dicarboxylic acid esters do not appear as stabilizers.

Of the esters, those that are longer-chain are suitable aliphatic ^ alcohol residues with. contain at least 12 carbon atoms while the esters with short-chain alcohol residues, such as the ethyl

· ■■ esters, show only a · slight stabilizing effect. Long-chain aliphatic alcohol residues are in the

■ Esters are particularly desirable because a longer paraffin chain makes the stabilizer more compatible with the polyolefin causes. In addition, the tendency of the stabilizer to sweat with growing coal water, rstpffkette decreased.

The polysulfide dicarboxylic acid esters can, for. B. in a known manner by implementing the corresponding Mercaptocarboxylic acid ester of the constitution

HS - R '- COO · R

(R '= CmH ₂ M, R has the same meaning as above) by oxidation with iron (III) chloride, with monosulfur dichloride or disulfur dichloride in petroleum ether as a solvent.

309 620/229

The polyolefins which can be found according to the invention; stabilize are homopolymers and copolymers of unsaturated hydrocarbons in general formula

..; H ₂ C = CHR "

wherein R "represents hydrogen or a hydrocarbon radical of up to about 20 carbon atoms. The stabilization proceeds particularly favorably in such cases Compounds in which -R "represents a straight-chain or branched saturated aliphatic radical. Examples include: polyethylene, polypropylene, poly-n-butene, polymethylbutene, polymethylpentene, of those, in turn, those that were produced with the help of Ziegler catalysts, the process in particular are accessible.

The total amount of anti-aging agent required is generally 0.001 to 2%> for normally stressed fittings preferably 0.05 to 1%. :

The stabilization of the polyolefins according to the invention can be carried out so that the poly-5 olefins. Stabilizing components are added after production. However, it is particularly advantageous to add the stabilizers to the polyolefins as early as in the working-up process for the polyolefins. .

example

The table below shows those measured at 140 ° C Embrittlement times for low pressure polypropylene, each 0.5% of that mentioned in column 1 Contains stabilizer, reproduced. The time in days after which a 1 mm thick pressed polypropylene film breaks when it is bent.

Stabilizer embrittlement time in days at 140 ° C

Color of the pre-plate after tempering

without stabilizer . '.

Monosuhid-diacetic acid-iThiodiglycolic-acid-dihexadecylester * Monosulfide diacetic acid (thiodiglycolic acid) didodecyl ester *. Monosuhid-diacetic acid-CThiodiglycolic acid-dioctadecyl ester *

Disulfide diacetic acid dihexadecyl ester *

Disulfide diacetic acid didodecyl ester *

Disulfide diacetic acid dioctadecyl ester

Trisulfide diacetic acid *

Trisulfide diacetic acid diethyl ester *

Trisulfide diacetic acid dioctyl ester *

Trisulfide diacetic acid didodecyl ester

Trisulfide diacetic acid dioctadecyl ester,

Tetrasulfide diacetic acid diethyl ester *

Tetrasulfide diacetic acid dioctyl ester *

Tetrasulfide diacetic acid didodecyl ester

Tetrasulfide diacetic acid dioctadecyl ester

Trisulfide dipropionic acid didodecyl ester

Didodecyl tetrasulfide dipropionate

Tetrasulfide dipropionic acid dioctadecyl ester

/ CH ₂ - CH ₂ - S - CH ₂ - CH ₂ - COO - C ₁₂ H ₂₅

^ CH ₂ -Ch ₂ -S-CH ₂ -CH ₂ -COO-C ₁₂ H ₂₅

Disulfi d-dicyclohexylcarboxylic acid dioctadecyl ester

Trisulfide dicyclohexylcarboxylic acid dioctadecyl ester

Dioetadecyl tetrasulfide dicyclohexylcarboxylate

* Comparative tests.

some hours

.1 1 1.

17 17 24

1 1

19 26 40

21 27 38

> 28 28 26

32

27 32 32

yellow

bright bright bright

yellowish yellowish yellowish

yellow

colorless

colorless

colorless

colorless

yellow colorless colorless colorless

colorless

colorless colorless light yellow

The table shows that the higher the carbon octadecyl ester, excellent stabilizers

The hydrogen chain of the ester provides the stabilization 65. . ■

effect increases very quickly. Thus, the show the superior effect of the inventively

Diethyl esters of polysulfide diacetic acids have not been used as stabilizers compared to the state of the art

Stabilizing effect, while the dodecyl and technique still shows the following comparative experiment: ■: ■■

Stabilizer (0.5% additive)

Monosulfide-dipropionic acid-dioctadecyl ester (according to USA patent specification 2,519,755)

Compounds used according to the invention:

Disulfide dipropionic acid dioctadecyl ester

Trisulfide dipropionic acid dioctadecyl ester

Embrittlement

time in days

at 140 ° C

20th

35 38

Claims (1)

PATENT CLAIM: Process for stabilizing homopolymers or copolymers of -olefins by esters of thio-dicarboxylic acids, characterized in that compounds of the general formula R · OOC - R '- (S) »- R' - COO · R are used, where R, when m = 2, an octadecyl radical and when m - 3 or 4, an alkyl radical with at least 12 carbon atoms, an aryl or cycloalkyl radical and R 'represents aromatic or cycloalkylene radicals, hydrocarbon chains interrupted by heteroatoms or the group (CH ₂ ) B is where η is an integer between 1 and 20. Considered publications:
Belgian Patent No. 562,623;
U.S. Patent No. 2,519,755.