DE2025336C2 - Use of amides as aging-resistant comonomers in a free radical polymerization of conjugated dienes - Google Patents

Description

where R _{3 is} an aryl radical, R and Ri are hydrogen or alkyl radicals with 1 to 4 carbon atoms, R _{2 is} hydrogen, alkyl radicals with 1 to 4 carbon atoms, alkoxy radicals with 1 to 4 carbon atoms or a radical of the formula

R ₄

N -

20th

R ₅

represents, where R _{4 stands} for alkyl radicals with 1 to 12 carbon atoms, cycloalkyl radicals with 5 to 12 carbon atoms, aryl radicals with 6 to 12 carbon atoms

25th or aralkyl radicals with 7 to 13 carbon atoms and R _{5 represents} hydrogen or alkyl radicals with 1 to 12 carbon atoms and R ₄ and R ₇ symbolize hydrogen or alkyl radicals with 1 to 4 carbon atoms, R, hydrogen, alkyl radicals with 1 to 4 carbon atoms, aryl radicals with 6 up to 12 carbon atoms, aralkyl radicals with 7 to 13 «? carbon atoms, cycloalkyl radicals with 5 to 12 carbon atoms, a carboxymethyl radical or a carbalkoxymethyl radical and R, hydrogen, alkyl radicals with 1 to 4 carbon atoms, aryl radicals with 6 to 12 carbon atoms, cycloalkyl radicals with 5 to 12 carbon atoms, carboxyl radicals or carbalkoxymethyl radicals mean, as aging resistant comonomers a free radical polymerization of conjugated dienes.

Practically all types of rubber, both natural and synthetic rubber types, and in particular rubbers made from dienes are known to be opposite are susceptible to destruction which is a consequence of a Oxidative aging is. Much effort has been made to develop various stabilizing agents which in effective catfish inhibit the adverse effects of aging on polymers. Unfortunately, however, many of the commercially available stabilizers are volatile when the polymeric Products are exposed to elevated temperatures during longer tent spans. Further these stabilizers are quickly removed from the polymeric masses by repeated washing with them extracted from aqueous detergent solutions or organic solvents. Such severe conditions occur when washing or dry cleaning clothes frequently. which contain rubber.

According to the status described in BE-PS 6 30 094 N- (4-Anlllnophenyl) -malelnsaurelmld adds a little volatile anti-aging agent to the technology Added to rubbers. This addition also gives the rubber a very good resistance achieved against oxidative degradation at elevated temperature. After the anti-aging agent in it however, it is not polymeric. Such stabilized rubbers have the disadvantage already set out above easy to wash out.

The object of the invention was therefore to produce of polymers that are very resistant to oil aging at elevated temperatures To use anti-aging agents and to combine with the polymer in such a way that the stabilized polymer even after repeated exposure to aqueous detergent solutions or chemical detergent liquids against oxidative aging Is very resistant to elevated temperatures.

The subject of the invention is thus the use of the amides described in the claim Formula (I). When used according to the invention, the Anti-aging agent polymerized into the polymer. It was already known from BE-PS 6 30 094. N- (4-Anlllnophenyl) -malelnsäurelmld as an antioxidant to use for rubber. However, this anti-aging agent is used as a comonomer in the polymer lsa- tion of butadiene! 1.3) not very suitable as it is only In takes part in the polymerization to a small extent and causes undesirable discoloration of the polymer. It was therefore not close to being unsaturated Amides as aging-resistant comonomers to use a free radical polymerization of conjugated dienes, since it was to be feared that that antioxidants based on unsaturated amides interfere with the described polymerization process and lead to undesirable by-products, such as the Auf occur a strong red color S.j1 the attempt of Polymerization of N- (4-Anlllnophenyl) -malelnsäuiJimId as a Known Antioxidant In Polybutadiene. On the contrary, it was surprising that from the multitude of possible unsaturated amides just these can be found duly used in contrast to the known Let N- (4-Anlllnophenyl) -malelnsäurelmid with high conversion in polybutadiene without discoloration of the copolymer. In the compounds of formula I, the carbal

bo koxymethyl radicals preferably have the following structure:

-CH ₂ - COR ₁₀ (D)

Il
ο

· "Where R, o is an alkyl radical with 1 to 4 carbon atoms is.

The carbalkoxy radicals preferably correspond to the formula

-COR ₁₁

Il ο

wherein Ru is an alkyl radical with 1 to 4 carbon atoms Is.

In the compounds of the formula I, R _{5 is} preferably a phenyl radical, but it can also be any other aryl radical, for example a naphthyl radical. R _{2 is} a radical of the formula

10

N -

15th

30th

35

then R _{2 is} preferably in the p-position. R ₆ and R ₇ preferably consist of hydrogen or methyl. In the formula I, R, preferably from hydrogen or methyl R. «and R _n , in the preferred carbalkoxymethyl radicals or carbalkoxy radicals are preferably methyl or ethyl radicals.

Representative amides that can be used in the present invention are as follows:

N- (4-Anlllnopheny I) -acrylam Id N- (4-Anlllnophenyl) -methacrylamId N- (4-Anillnophenyl) -cinnamld N- (4-anilinophenyl) crotonamide N- [4- (4-Melhylanillino) -phenyI] -acrylam! D N- [4- (4-methylate ;; ino) phenyl] methacrylamide N - [- {4-methoxyanllino) phenyl] arylamide N- [4- (4-MethoxyanIIIno) -phenyI] -methacrylamide N- [4- (4-Etoxyanlllno) -phenyl] -i3cryla. ' ^r »ld N-14- (4-ethoxyanlllno) -phenyl] -metfiacrylamide N- [4- (4-N, N-Dlmethylamlnoanlllno) phenyI] -

acrylamld

N- (4-Anillnophenyl) -maleInsauremonoamId N- (4-Anillnophenyl) -itaconsäuremonoamId _4Q

N- [4- (4-Methylanlllno) phenyl] -

malelic acid monoamld N-iAnllinophenyO-cltraconic acid monoamld

The process of making the amides of Formula I is not critical to the effectiveness of these compounds when used in accordance with the present invention.

The amides can be obtained by reacting (usually in substantially equimolar amounts) of an amine the formula like this

55

60

NH ₂

Ri R ₇

with an acid halide of the formula HC = C-C-X

I I Il

R ₉ R «O

are prepared, where in the formulas R, Ri. Rj, Ri, Rj, R «, R ₆ , R ₇ , R, and R« have the definitions given above, while X stands for chloride or bromine radicals. The reaction takes place in the presence of an agent which absorbs the acid. It can an inorganic salt, for example sodium carbonate, or an organic tertiary amine, for example triethylamine. The reaction will usually carried out in such a way that a solution of the acid chloride in an apron is dropwise Solvent is added to the solution of the amine which contains a compound in solution or in suspension, which is able to react with the hydrogen halide formed during the reaction. You can -jinen Use a slight excess of the acid halide. the Reaction is usually exothermic. The temperature is kept at a maximum of 50 ° C. during the reaction, and by means of an Els- / water bath. The reaction mixture is for a period of 1 hour or stirred over it after completion of the addition of the acid halide. The product usually falls during the Reaction off. It is then filtered off, dried and, if necessary, purified.

Examples of amines which can be used to prepare amides of the formula I are as follows:

4-An "iinodipuenylarn! N

4-Amino-4'-methyldlphenylamine

4-AmIno-4'-methoxydiphenylamine

4-Amino-4'-ethoxydiphenylamine

4-Amtno-4 '- (N, N-dimethylamino) -diphenylamine

4-Amino-4 '- isopropyldlphenylamine

Examples of acid halides that can be used to make the amides are as follows:

Acryloyl chloride Methacryloylchlorld Crotonylchlorld Cinnamic acid chloride Acryloyl bromide

The amides mentioned above are used in your Use according to the invention according to known ones. Polymerization methods based on free radicals polymerized. The polymerizations can be carried out in emulsion, suspension, in bulk or in solution will. If necessary, certain adaptations in the polymerization approach and / or with regard to the Conditions are necessary to achieve a satisfactory rate of polymer formation, and depending on the amount of the monomeric anti-aging agent and the other monomers used. These adjustments should, if necessary, serve to counteract the inhibiting effect of the monomeric anti-aging agent and to ensure its solubility in the system. Furthermore can Solvents may be required to have an appropriate To achieve solubility of the monomers with respect to one another, and optionally to other constituents to solve. Some solvents, such as Methyl ethyl ketone or isopropyl alcohol can be used to advantage in connection with an emulsion polymer solution system.

Examples of free radical initiators suitable for practicing the invention are those initiators known as "redox" initiators , e.g. B. corresponding combinations of lightened elsenic salts, sodium formaldehyde sulfoxylate and organic hydroperoxides, such as cumene and p-menthane hydroperoxide. Other initiators, such as, for example, azolesobutyronltrll, benzoylperoxide. Hydrogen peroxide and potassium persulfate are also suitable, depending on the polymerization system.

The inventive use of amides of

Formula I as aging-resistant comonomers in a polymerization taking place via free radicals of conjugated dienes includes both their use in the polymerization of at least one conjugated dienes Diens, such as butadiene- {1,3), 2-chlorobutadiene- (1,3). Isoprene and / or piperylene, as well as their use in the copolymerization of at least one these conjugated dienes with at least one comonomer from the group of vinyl and vinylidene monomers Styrene, jr-methylstyrene, divinylbenzene, vinyl chloride. Vinyl acetate, vinylidene chloride, methyl methacrylate, ethyl acrylate, vinyl pyridine, acrylonitrile, methacrylic acid. Methacrylic acid and acrylic acid. Mixtures of monomeric anti-aging agents can also be used here be used. The monomer charge weight ratio is usually 0.10 / 99.9 to 10/90, and monomeric anti-aging agent / other monomers. A batch ratio of 0.5 / 99.5 to 5.0 / 95 is preferred. The ratios will vary depending on the amount of anti-aging agent that is bound should, as well as depending on the reactivity ratios of the monomers in the particular polymerisation system.

The monomer system contains at least 50 parts by weight per 100 parts by weight, based on the total monomers, of at least one conjugated diene such as for example butadiene ^ 1,3) or isoprene.

One embodiment of the present invention provides for the use of a monomer system which is composed of 50 up to 99.9 parts of at least one conjugated diene, 0 to 49.9 parts of at least one monomer from the group of the above-mentioned vinyl monomers or vinylidene monomers, and 0.10 to 5.0 parts by weight at least of a monomeric aging inhibitor, all parts by weight per 100 parts by weight of the total Amount of monomer are. Preferably at least 0.5 part of the monomeric aging inhibitor is used. If at least 0.5 part of the monomeric anti-aging agent is used, then the upper limit is used Limit the diene monomer range at 99.5 parts, while the upper limit of the vinyl monomer and / or the vinylidene monomer is 49.5 parts.

In carrying out the invention, the monomers are selected such that elastomeric copoly · mers are generated.

The polymers that are used in the implementation of the Invention, contain monomer units of the following structures:

50

R, H

(IV)

55

60

65 in which R, Ri, Rj, Ri, R ₆ , Rt, Rs and R «idle have the meanings given above under the formula I.

To provide adequate protection against decomposition To achieve, the polymers must have 0.10 to 10.0 parts by weight of the monomer units of the amide per 100 Parts by weight of the polymer contain, however, 0.50 to 5.0 parts and 0.50 to 3.0 parts are also satisfactory Parts are preferred. As the amount of bound anti-aging agent increases, the corresponding Way changes the physical properties of the polymer. If a polymer is to be produced, which has a self-stabilizing effect, and essentially the physical properties of the comonomer or the comonomer retains, the polymer typically cannot exceed about 10.0 parts by weight of the amide monomer units. Such polymers are preferably solid, although they are also liquid could be.

These polymers, regardless of whether they are in Liquid or in solid form are of particular advantage in this respect. a! s the:! aging-resistant part is not extractable, so that the copolymers In high Dimensions are resistant to oxidative aging, even after repeated exposure from aqueous detergent solutions or from chemical cleaning liquids. This feature is of particular importance when using polymers in foam underlays used for carpets. Furthermore, this feature plays a significant role when polymers are used in In the form of a solution or in the form of a latex can be used for treating tissues, as such Products are often exposed to aqueous detergent solutions or dry cleaning liquids will.

One of the advantages of carrying out the invention is that it results in polymers that are built-in Contain stabilizers without forming noticeable amounts of gel. This means, that the polymers are essentially gel-free! are. One Gel formation is generally undesirable in a polymer, as it causes processing difficulties and directly and / or indirectly the physical properties of the polymer in its vulcanized state. Usually is a macro gel less than 50% suitable. However, a gel content of less than 10% is preferred. In very preferred catfish, an attempt is made to achieve a gel content below 5%. The gel is the one Amount of polymer contained in an organic Solvent, such as benzene, is insoluble. There is one way to measure the gel content therein, about 0.20 to about 0.30 g of the polymer in Introduce 100 ml of benzene and mix the mixture for 48 hours to let stand for a long time. The mixture is then filtered through a cloth of stainless steel wire with a mesh opening of 0.15 mm, the wire diameter of the steel wire is 1.14 mm. Then the solids content of the filtrate is determined to the Determine the amount of soluble polymer. The amount of gel is the difference between the amount of polymer, which were originally introduced into the benzene Is, and the amount of soluble Pe'.ymeren. Of the Percentage of the gel is 100 times the weight of the gel, divided by the original polymer weight.

Another advantage of the internal polymer solution monomeric anti-aging agents In the polymers through free radical polymerizations is achieved, in contrast to a mere physical

kall's incorporation of the monomeric amine of the formula I, for example by adding to the polymer latex or by grinding or processing in one Mixer, in that in the first-mentioned method, d. H. in the case of the polymer solution, a much better one Color is achieved as the worms age.

In the following examples and Amld production trials Unless otherwise stated, all parts are based on weight.

Production of monomeric anti-aging agents

N- (4-Anlllnophenyl) -acrylamid is by adding a solution of 10 g Acryloylchlorld In 50 ml Benzene In a flask containing 18.4 g of p-amldodlphenylamine, 6 g of sodium carbonate and contains 100 ml of benzene. The addition is complete after 50 minutes at 30 to 40 ° C. The mixture is used over a period of time Stirred for 2 hours, after which the precipitate formed is filtered off, washed thoroughly with water and dried will. The yield is 15.5 g (65%), while the Melting point of the product was found to be 148 to 150 ° C will.

example 1

The polymerization described below is carried out in a 120 ml bottle fitted with a screw cap with a Teflon seal. To a solution of 0.8 g of sodium dodecylbenzenesulfonate, 0.026 g of the sodium salt of naphthalenesulfonic acid condensed with formaldehyde, 0.08 g of potassium phosphate and 38 ml of water is added 1 g of N- (4-AnlllnophenyD-acrylamld. 6 inoculations of tert .-Dodecyl mercaptan, 5 g of acrylonitrile and 15 g of butadiene (1.3) were added. 3V ₂ ml of a solution containing 0.008 g of a 34% aqueous solution of a 90/10 mixture of the tetrasodium salt of EthylendlamlnotetraesslgsSurs t! I! D of the monosodium salt of NN-d! - (l-HydroxyethyD-glycol, hereinafter referred to as the chelating agent, 0.008 g FeSO ₄ 7H ₂ O and 0.006 g sodium formaldehyde sulfoxylate dissolved in water are then added, followed by addition of 0.24 ml of a solution containing 0.012 g p-menihanum hydroperoxide dissolved in benzene Shaken in a polymerization bath at a temperature of 25 ° C. for a period of 18 hours. The conversion is 84.5%. The polymer is coagulated by adding the latex to 250 ml of isopropyl alcohol. It is then washed thoroughly with water and allowed to dry.

The dry polymer is left with for 48 hours Methanol In a Soxnlet device for removal extracted from any free monomeric anti-aging agent still present, dried again and then dissolved in benzene. The benzene solutions are poured into aluminum dishes, whereupon the Solvent is allowed to evaporate. The obtained films are placed in an oxygen absorber given. The amount of oxygen absorbed in a certain period of time is determined. The corresponding Values are summarized in Table I below. The test method is described in more detail in »Industrial and Engineering Chemistry ", Volume 43, page 456 (1951) and" Industrial and Engineering Chemistry ", Volume 45, page 392 (1953).

Comparative experiment A

A polymer is produced and processed according to the procedure described in Example 1, with the exception that no amide is present in the polymer isa-uonsaneiz is used. The oxygen absorption values for this polymer are also collected and are summarized in Table I.

Comparative experiment B

In addition, the N- (4-Anlllnophenyt) -acrylamid as Common antioxidant In SBR-1006 (consisting of from 25 wt .-% styrene and 75 wt .-% butadiene ίο by polymerization at 38 ° C with a fatty acid emulsifier and coagulation with an acid and / or a salt; Mooney viscosity = 50) tested. The SBR polymer (1006) is dissolved in benzene, whereupon benzene solutions the aging inhibitors described above are added to parts of the SBR solutions, in such an amount that 1.00 part of the anti-aging agent per 100 parts of the rubbery polymer. The benzene solutions are used to

Γίκ vcri Fi'msri vsrwsniis!

rsi! in a

absorption device In the one described above Catfish tested.

Table I.

Antioxidants

Hours to 1% oxygen
are absorbed
installed in SBR-1006 at 90 ° C 100 ° C

jo none ¹ ) 1

N- (4-anilinophenyD-520
acrylamide ^:)

500

¹ l (75/25) butadiene / acrylonitrile
³ ' ^:) (75/25/5) butadiene / acrylonil / acrylamide

Example 2

The copolymerization of Example 1 is carried out in the following Catfish carried out:

The amounts of the ingredients listed below are screw-capped 120 ml bottles filled according to example 1:

Parts

Isoprene 19th Acrylonitrile 1 Methanol 6th N- (4-Anillinophenyl) acrylamide 0.2 HCl ') 70% lges HjO ₂ 0.0

ι) 0.1 mol equivalent of HCl, added per mole of N- (4-Anlllnophenyl ! -acrylamide

The bottle is capped and immersed in a water bath at 80 ° C for a period of 1? Shaken for hours. After that, it is removed from the bath and cooled in a refrigerator. Another 0.08 part of 70% H ₂ O ₂ is added to the bottle. After a further shaking for a period of 17 hours in the water bath at 80 ° C, the bottle is again cooled in a refrigerator. A small aliquot is evaporated to dryness to determine the conversion. The conversion is 38.3%.

The liquid polymer that is produced during this polymerization is obtained, is isolated and cleaned in the following way: The contents of the Polymerisatlonsflons are in a Shaken beaker containing 200 ml of methanol. the

Mixture is stirred thoroughly and the liquid polymer is allowed to settle. The supernatant serum is decanted and the polymer is dissolved in 50 ml of benzene. The liquid polymer is again by adding «200 m! Precipitated methanol, whereupon the supernatant liquid is decanted. The polymer is dissolved again, and filled with methanol, UNR ¹ although total of three times. The milky, viscous and liquid polymer is dried in a vacuum oven at 50 "C.

3 g of the liquid polymer are dissolved in 25 ml of benzene, whereupon 0.2 g of toluene isocyanate are added. Half of the solution is then put in one at a time poured from two weighed aluminum bowls. The dishes are left to stand under a hood at room temperature until the benzene has evaporated Is. They are then placed in an oven with a Temperature of 55 ° C for a period of 72 hours. The cured films are then transferred to the oxygen absorber and Tested in the same way as the Example 1 polymer. The test result obtained lsi In der Table II summarized.

Table Il

example

Antioxidants

Hours until 1% oxygen is absorbed at 90 ° C

N- (4-anilinophenyl) acrylamide ⁴ )

103

⁴ ) - (95/5/1) isoprene / acrylonitrile / acrylamide

Example 3

The following approach is used to produce a Butad! En / Styro! / Acrylam! D-Teroolymeren.

Parts

Butadlene-0.3) 75 Styrene 25th N- (4-Anylnophenyl) -acrylsäureamld 2.5 tert-dodecyl mercaptan 0.24 50/50 mash of a potassium elf disproportionated rosin acid and a sodium soap of a fatty acid 4.5 Tricallum phosphate 0.25 Sodium salt of with formaldehyde condensed naphthalenesulfonic acid 0.08 water 200 Na ₂ S ₂ O ₄ 0.056 FeSO ₄ • 7H ₂ O 0.015 Chelling agent 0.070 Sodium formaldehyde sulfoxylate 0.050 p-menthane hydroperoxide 0.12

The ingredients are poured into a 250 ml bottle, which is provided with a screw cap and a self-sealing seal so that aliquots can be removed with an injection needle in an amount which corresponds to one fifth of the batch weight, in g. The following operating regime is observed: The N- (4-anilinophenyl) acrylamide is dissolved in methyl ethyl ketone to produce a 4% solution. The soap, K ₃ PO ₄ and the sodium salt of naphthallic sulfonic acid condensed with formaldehyde are dissolved in 75% of the water and

Put in the bottle. Half of the styrene, which contains the tert-dodecyl mercaptan, and the solution of the acrylamide are added. The butadlene- (1,3) is added in a slight excess and the excess is allowed to evaporate to displace air from the bottle prior to sealing. The chilling agent FeSO ₄ · 7H ₁ O. Na ₁ S ₂ O ₄ and sodium formaldehyde sulfoxylate are dissolved in the rest of the water and added to the bottle using the injection syringe. The bottle is then placed in a water bath at a temperature of 5 ° C and shaken for about four and a half hours. The remainder of the styrene, which contains the P-menthane hydroperoxide, is added by means of an injection syringe. The bottles are shaken at 5 ° C for a period of 65 hours. The final turnover is 65%.

The polymer in the form of small crumbly particles is obtained by slowly pouring the contents of the bottles into 600 ml of methanol. Since the supernatant liquid is cloudy, 10 ml of 1.0 nH ₂ SO _{4 are} added to make this liquid acidic. This results in the formation of light blue colored crumbs in a clear supernatant liquid. The liquid is decanted off and replaced with 800 ml of acidified isopropyl alcohol to remove non-polymerised monomers and other non-rubber-like components. The crumbs are washed one more time with methanol and dried in a vacuum oven.

Example 4

A butadlene / Acrylnltrll (67/33) copolymer containing N- (4-Anlllnophenyl) -acrylamid-Elnhelten is prepared in the same way as the polymer of Example 3, except that the tert-dodecyl mercaptan and the p-menthane hydroperoxide can be dissolved in portions of the acrylonitrile, the amount of p-menirefi-hydroperoxide being increased to 0.6 parts per 100 parts of the butadlene / acrylic mixture. It is a ausreicheP'le amount of 4% lgen methyl ethyl ketone solution of / \ _w iamlds added to provide about 1.88 parts per 100 parts of les Acrylamlds Butadlen / Acrylnltrll-Mlschung available. This polymerization is carried out at 20 ° C. for a period of 4.5 hours. After this point, the conversion is 70%. The polymer is obtained in the same way as in Example 3.

The products of both Example 3 and Example 4 are made in the same way as the polymer of Example 1 extracted. The purified polymers of Examples 3 and 4 are then placed in the oxygen adsorption device in the same manner as the Polymers of Example 1 tested. The results are summarized in Table III.

Table IH

example

Antioxidants

% Oxygen, sorted from hours at 100 ° C

3 N- (anilinophenyl) - 0.5 acrylamide ⁵ )

4 N- (anilinophenyl) - 0.78 acrylamide ⁶ )

⁵ ) (75/25 / 2.5) butadiene / styrene / acrylamide

⁶ ) (67/33 / 1.88) butadiene / acrylonitrile / acrylamide

330

358

Comparative experiments C and D

If the polymerizations of Examples 3 and 4 In In the absence of the aforementioned acrylamide, the polymers absorb 1% oxygen in less than 5 hours at 100 ° C.

Example 5

A polymerization is carried out by a method which is similar to the method described in Example 3, with the exception that only 1.25 parts of 4- (anllinophenyl) acrylamide are added. The extracted polymer absorbs \% oxygen at 100 ^° C. in 323 hours.

The self-stabilizing polymers can, as already mentioned above, be liquid or solid. Number averages of molecular weights vary

from 20,000 or less (down to 5000) up to 100,000 or even 210,000.

The aging-resistant copolymers, which by chemical bond of the anti-aging agents in the Polymers are resistant to aging, regardless of whether they are vulcanized in or non-vulcanized form. You can ever after which polymers are used in the manufacture of a wide variety of products, for example in the manufacture of car elves, industrial rubber products such as z. B. Belts and hoses, as well as molded objects. They are particularly suitable for areas of application in which the products are frequently aqueous Detergent solutions or chemical detergent liquids. For example, come a use for the production of foam pads for Carpets and a use for treating fabrics in question.

Claims (1)

Claim: Use of amides of the formula R ₁ -R ₃ -NH Ri NH — C — C = HC — R, O R,