DE2145110A1 - MEANS AND METHODS TO COMPENSATE FOR THE REDUCTION OF PROCESSING TIME CAUSED BY PHENYLENEDIAMINE IN RUBBER MATERIALS - Google Patents

Description

When processing rubber materials, various components are ground together with the rubber. One of the problems encountered with such a marriage is referred to in the industry as "scorch" and relates to the pre-vulcanization of the rubber before it cures. In practice, manufacturers need time to to handle, transport and process the rubber before it is heated to form rubber products and is vulcanized.

The "scorch" time or processing time is noticeably shortened if a phenylenediamine is used in the rubber compound Antiozonant is incorporated. However, it is very desirable to use the phenylenediamine anti-ion zonant to

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to protect the product against attack by ozone. Accordingly, it is also desirable to find means to get the benefits to maintain the ozone protection and still get a sufficient "scorch" time or processing time, which allows the handling, transport and processing of the rubber compounds before final vulcanization.

It has now been found that the N-aryl-2-benzothiazolesulfenamide to compensate for the fact that a phenylenediamine antiozonant is incorporated into the rubber compound tied decrease or shortening of the processing time or "Scorch" time is used.

Any suitable N-aryl-2-benzothiazole sulfenamide is used in accordance with the present invention. Particularly preferred are for example N-phenyl-2-benzothiazole sulfenamide and the tl-substituted phenyl-2-benzothiazole sulfenamides. Specific examples include N-phenyl, N-p-methy! Phenyl and N-p-methoxyphenyl-2-benzothiazole sulfenamide. Another suitable phenyl derivative is W-p -chlorophenyl-2-benzothiazole sulfenamide. But it can also other N-alkylphenyl or N-dialkylphenyl derivatives be used. The alkyl group preferably contains 1 to 6 carbon atoms in each case. examples for this are N-p-Ethylphenyl-, N-p-Propylphenyl-, N-Buty! Phenyl-, N-Pentylphenyl-, N-p-hexylphenyl-2-benzothiazole sulfenamide and corresponding compounds in which the alkyl group

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is in the ortho or meta position, though this does not necessarily produce the same results.

Other exemplary compounds are N-3,5-dimethylphenylbenzothiazole-2-sulf enamid, "N-3,5-Dipropylphenylbenzothiazol-2-sulfenamid, N-3,5-Dibutylphenylbenzothiazol-2-sulfenamide, N-3,5-dipentylphenylbenzothiazole-2-sulfenainide and ίϊ-3,5-dihexylphenylbenzothiazole sulfenamide and corresponding compounds in which the alkyl groups are in the 2,3-position, 2,4-position, 2.5 position or 2.6 position.

The N-aryl-2-benzothiazole sulfenamides for use in accordance with the present invention are specially prepared by oxidative condensation. For example, mercaptobenzothiazole is mixed with the desired arylamine in alcohol solvents and alkali metal hypochlorite. implemented below OC and especially between -20 and OC. For example, u-phenyl-2-benzothiazolesulfenamide is prepared by preparing a solution of 2-mercaptobenzothiazole, aniline and aqueous sodium hydroxide in methanol and cooling the solution to below 0 ° C. in a! -, is-alcohol bath. An aqueous solution of sodium aypochlorite is prepared separately from this and also cooled to ^{a temperature below f> C.} The second solution is added with continued stirring

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added to the first solution and stirring is continued, until the reaction is over. The desired sulfenamide forms a solid product that emerges from the reaction mixture recovered by filtration and used as such or purified, such as by eluting with Ether from an aluminum oxide column. ·

As described above, the N-aryl-2-thiazole sulfenamide used in any rubber composition containing a phenylenediamine antiozonant. The rubber compounds, which can be treated after the present invention, include natural and synthetic rubber materials that undergo curing during their manufacture will. In general, rubber is classified as a vulcanizable diene hydrocarbon rubber and includes polymers of conjugated 1,3-dienes, either as homopolymers thereof or as interpolymers thereof with other polymerizable compounds. Natural rubber materials are, for example, Hevea rubber, rubber, Balata and Gutta-percha. Synthetic rubber materials are, for example, butadiene-styrene copolymer rubber, which is known in the art as SBR rubber, Buna-N rubber (NBR) made from butadiene-isobutylene, Neoprene rubber, ethylene propylene copolymer rubber (EP), Terpolymer rubber materials such as EP terpolymers, polychloroprene, Polyisoprene and polybutadiene. The term "rubber" is intended to include both synthetic and natural

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include natural rubber materials which undergo curing as a step in their manufacture.

The N-aryl-2-benzothiazole sulfenamide is used in conjunction with any suitable phenylenediamine antiozonant. In one embodiment, the phenylenediamine antiozonant is an NN ¹ -di-sec-alkyl-p-phenylenediamine in which each alkyl group contains 3 to about 20 carbon atoms and preferably about 6 to about 10 carbon atoms. Preferred antiozonates are those in which the alkyl group is the heptyl group, especially the 1,4-dimethylpentyl group, or the octyl group, especially the 1-ethyl-3-methylpentyl group, or in which the alkyl group is also the 1-methylheptyl group, especially the 1 -Methylpentyl- or Iräthylbuty! Group, can be. Other heptyl groups that can be used are the 1-ethylpentyl and 1-propylbutyl groups. Other alkyl groups are the octyl, especially the 1-propylpentyl, the nonyl, especially the 1-methyloctyl, 1-ethylheptyl or 1-butylpentyl, and the decyl, especially the 1-methylnonyl, 1-ethyloctyl -, 1-propylheptyl or 1-butylhexyl group.

In another embodiment, it is a phenylenediamine antiozonant an N-phenyl-N'-sec-alkyl-p-phenylenediamine, in wherein the alkyl group contains 3 to about 20, and preferably 3 to 10 carbon atoms. Antiozonants are particularly preferred according to this embodiment, in which the alkyl

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group is the 1,3-dimethylbutyl or 2-octyl group. The alkyl group can also be isopropyl, 1-methylpropyl, sec-pentyl , especially 1-methylbutyl or 1-ethylpropyl, sec-hexyl, especially 1-methylpentyl or 1-ethylbutyl, sec -Heptyl, especially 1-methylhexyl, 1-ethylpentyl, 1-ethyl-3-methylbutyl or 1-propylbutyl, sec-octyl, especially 1-ethylhexyl, 1-ethyl-4-methylpene - ^ i or 1-propylpentyl , the sec-nonyl, especially the 1-methyloctyl, 1,6-dimethylheptyl, 1-ethyl, 'heptyl or 1-propylhexyl, and the sec-decyl, especially be the 1-methylnonyl, 1,7-dimethyloctyl, 1-ethyloctyl, 1,5-diethylhexyl or 1-butylhexyl group.

In yet another embodiment, it is a phenylenediamine antiozonant an N ^ N'-dicycloalkyl-p-phenylenediamine and especially N-N'-dicyclohexyl-p-phenylenediamine.

The phenylenediamine antiozonants are commercially available or can be prepared in any suitable manner will be presented. In a preferred method, throw them prepared by reductive alkylation of p-phenylenediamine or p-nitroaniline with the desired ketone. For example becomes ^, N'-di-d-methylheptylJ-p-phenylenediamine obtained by reductive alkylation of 1 mole of p-nitroaniline with 2 moles of methylhexyl ketone. Prepares in a similar way to carry out N-phenyl-N '- (l / 3-dimethylbutyl) -p-phenylenediamine reductive alkylation of equal molar ratios of p-aminodiphenylamine, p-nitrodiphenylamine or p-nitrosodiphenyl-

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amine with methyl isobutyl ketone. Similarly, N-phenyl-N ¹ - (1-methylheptyl) -p-phenylenediamine is prepared by reductive alkylation of equal molar ratios of p-aminodiphenylamine with methylhexyl ketone. N, N ¹ -dicyclohexyl-p-phenylenediamine is also prepared by reductive alkylation of a hol p-nitroaniline with 2 moles of cyclohexanone.

The reductive alkylation is carried out in any suitable manner and generally under hydrogen pressure from about 7.8 to 205 atm or more, and preferably from about 69 to 137 atm, and at a temperature of about 93 to 260 C and preferably at a temperature of about 121 to 177 C. Generally, an excess will be used of ketone is used in the reaction mixture and this can contain up to about 20 or more moles of ketone per mole of p-nitroaniline or p-phenylenediamine. Any suitable reductive alkylation catalyst is used. A catalyst comprises an intimate mixture of copper oxide, chromium oxide and barium oxide. Other catalysts are for example those including nickel, molybdenum, platinum and / or palladium. A particularly preferred catalyst comprises a composition of alumina with about 0.1 to 10% or more platinum and optionally can also contain chlorine and / or fluorine contained in a total concentration of about 0.2 to 10% by weight.

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The phenylenediamine antiozonant is used in a sufficient Concentration used to bring about the desired stabilization. The concentration can range from about 1.5 to about 6 wt% and especially in the range of 2 to 4% by weight of the rubber, although higher or lower concentrations can also be used if desired. These concentrations affect the rubber hydrocarbon exclusively other components of the rubber compound and are used here with this meaning.

As stated above and explained by the following examples, the phenylenediamine antiozonant reduces the processing time, and such a reduction in the processing time is at least partially offset by the inclusion of the N-aryl-2-benzothiazolesulfenamide in the rubber composition. The N-aryl-2-benzothiazolesulfenamid is in an appropriate concentration is used to achieve the desired goal, and this concentration can be around 0.5 to about 3, and preferably about 1 to 2 parts by weight per 100 parts by weight of rubber hydrocarbon. The concentration figures used in the present invention are based on the rubber hydrocarbon weight calculated.

Conventional rubbers including those with extender oils can be used, and these can be excepted the phenylenediamine antiozonant and sulfenamide one or more antioxidants, retarders, fillers, plasticizers,

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Include extenders or wax reinforcing agents, examples of antioxidants are 2,6-di-tert-butyl-4-methylphenol, Phenyl-ß-naphthylamine, 6-phenyl-2, 2,4-trimethy1-1,2-dihydroquinoline, which is on the market under the trade name "Santoflex B", 2,2-methylenebis (4-methyl-6-tert-butylphenol) and the reaction product of acetone and diphenylamine, the enter of the trade name "B.L.E." is on the market. These antioxidants are generally used in a concentration of about 0.5 to about 3% by weight of the rubber hydrocarbon is used. The conventional accelerators can also be used in the rubber compound are incorporated, and these are, for example, other benzothiazole sulfenamides, other thiazoles, Thiuram sulfides, guanidine and dithiocarbamates.

If desired, the composition according to the present invention is also used together with paraffin and / or microcrystalline Wax, generally used at a concentration of about 0.5 to 3 percent by weight of the rubber.

In addition to the importance of extending the processing time, the addition must also not allow subsequent hardening adversely affect usai to make a rubber product with the maintains desired physical properties. It has been found that the variously substituted N-phenylbenzothiazole sulfenamides affect the properties of the cured product somewhat differently, and therefore will

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the N-aryl derivative taking into account the in the finished Rubber product selected properties desired.

Conventional milling procedures can be used with the N-aryl-2-benzothiazole sulfenamide in bulk either is incorporated separately or together with 1 or more other ingredients.

The following examples serve to further illustrate the invention.

example 1

N-Phenyl-2-benzothiazolesulfenamide was prepared by Preparing a solution of 34 g (0.2 MbI) 2-mercaptobenzothiazole, 46.5 g (0.5 mol) of aniline and 20 ml of a 50% aqueous solution of sodium hydroxide in methanol and cooling the Solution prepared at -8 ° C in an ice-alcohol bath. Sne a separate solution (150 ml) of 10% by weight sodium hypochlorite was prepared separately and cooled to -8 ° C. The second solution was added dropwise over a period of time of 20 minutes to the first solution with continuous stirring. The mixture continued for 30 minutes stirred and then filtered. This gave 10.5 g of solid material which consisted of the desired sulfenamide. The sulfenamide was eluted from a column of 45 g of aluminum oxide with a particle size of 74 Cleaned to 250 microns with ether (1.5 l), which is the

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N-phenylbenzothiazole sulfenamide with a melting point received from 126 to 129 ° C. The structure of the product was confirmed by nuclear magnetic resonance analysis and infrared analysis confirmed.

In essentially the same way, the corresponding N-methylphenyl- and N-p-ifethoxyphenyl-2-benzothiazole sulfenamides prepared, but instead of aniline, p-methylaniline and p-methoxyaniline were used as reactants used. In addition, other N-aryl-2-benzothiazolesulfenamides or N-aryl-2-thiazolesulfenamides manufactured by others Reactants were used in the production.

Example 2

The rubber composition of this example had the following composition:

Component parts by weight

SBR rubber 1502 100

Furnace soot 40

Zinc oxide 3

Stearic acid 2

Sulfur 2

Sulfenamide 1.25

Antiozonnns (if used) 3.32

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The ingredients were made by conventional milling methods mixed together and the composition was cured at 140 ° C for 40 minutes.

The scorch values or Verarbextungszeiten were with the large Rotor-Mooney viscometer at .121 C according to ASTM-D-1077-55 T determined. This instrument measures the torque required to operate one in a sample of the rubber material to rotate enclosed disc. An earlier version of this test is in "India Rubber World" Volume 117,

* Page 216, (1947), "Measurement of the scorch and cure rate of vulcanizable mixtures using the Mooney Plastometer ". The values recorded are the number of Minutes for a rubber containing a curing agent required to increase the viscosity, which is indicated by an increase in torque of 5.8 and then 2-3 cm / kg. This method simulates conditions that occur during milling. A high scorch value means a long processing time or a high one

t resistance to processing time reduction or a long period of time before the rubber viscosity increases.

The values in the following table are the results of the experiments.

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Experiment Benzothiazole No. sulfenamide

Antiozonation of
5.8 cm / kg

Mooney Scorch in Minutes for a Torque Down

23 cm / kg

1 N-cyclohexyl- no 56.1 60.8 2 It Yes 18.0 20.5 3 N-phenyl- no 82.6 115.2 4th Il Yes 48.0 56.4 5 Np-methyl
phenyl no 80.4 105.6 6th Ii Yes 43.7 49.8 7th Np-methoxy-
phenyl no 67.1 78.5 8th Il Yes 30.9 35.1

N ¹ -di-2-octyl-p-phenylenediamine.

As mentioned above, the sulfenamides were in one concentration of 1.25 parts by weight and the antiozonant in a concentration of 3.32 parts by weight per 100 parts by weight Rubber hydrocarbon used.

From the values in the table above it can be seen that the sulfenamides according to the present invention are satisfactory Extent to compensate for the decrease in processing time or scorch time with the addition of the antiozonant is connected to the rubber compound. For comparison purposes, it should be noted that this decrease in processing

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time was significantly less than when using N-cyclohexylbenzothiazole sulfenamides.

Example 3

The suitable hardening of the rubber compound is also important, to produce a product of the desired physical properties. The specially desired physi Physical properties depend on the end use of the rubber product. For example, the elongation is at P Breakage is an important requirement in the manufacture of rubber for use in rubber bands and the like.

In the composition described in Example 2, the sample possessed the gMche phenylenediamine antiozonant and N-cyclohexyl-benzothiazolesulfenamide contained a stretch at breakage of 550%. The samples containing the same antiozonahs and the N-phenyl, N-p-methylphenyl and N-p-methoxyphenyl derivatives had elongations at break of 445%, 520% and 575%, respectively. From this point of view Accordingly, the N-p-methoxy derivative is preferred.

Example 4

When considering the tensile strength as an essential requirement of the rubber product, apparently this is also N-p-methoxyphenyl derivative the best of the N-aryl derivatives. The sample containing the same phenylenediamine antiozonant and also contained N-p-methoxyphenylbenzothiazole sulfenamide,

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2 had a tensile strength of 195 kg / cm. This is just

2 slightly lower than the tensile strength of 211 kg / cm in the product containing the same phenylenediamine antiozonant and N-cyclohexylbenzothiazole sulfenamide.

Example 5

The rubber composition according to the recipe described in Example 2 was prepared so that it was 3 parts by weight H, N'-Di- (l, 4-dimethylpentyl) -p-phenylenediamine as an anti- ' ozonans contained per 100 parts by weight of rubber hydrocarbon. This reduces the processing time from 56.1 to 15.7 minutes for the torque increase from 5.8 cm / kg and from 60.8 to 17.1 minutes for the torque increase of 23 cm / kg. Here too, however, the incorporation of 1.5 parts by weight of N-phenyl-2-benzothiazolesulfenamide each serves 100 parts by weight of rubber hydrocarbon to this To partially offset the decrease, and such incorporation results in sufficient processing time to achieve a to allow practical handling of the rubber mass prior to vulcanization.

example 6

This example describes the use of the N-aryl-2-benzothiazole sulferiamide in a container sliding surface material of the present formulation:

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Components parts by weight

SBR rubber (Philiprene 1609) 145.0 soot 15.0 Zinc oxide 5.0 Mineral rubber (Witco 38 MR) 5.0 Stearic acid 2.0 sulfur 1.80 Santoflex DD 1.0 2
Agerite resin D 1.0 Santocure NS 0.65 DIBS 0.65 Antiozonant as stated

6-dodecyl-1,2-dihydro-2,2,4-trimethylquinoline

Polymerized trimethyldihydroquinoline N-tert-butyl-2-benzothiazolesufenamide

N, N-Diisopropylbenzothiazol-2-sulfenamide N, n'-dicyclohexyl-p-phenylenediamine

The sample of rubber produced from the basic formulation but without the antiozonant content had an increase in torque of 5.8 cm / kg at 61.3 minutes and an increase in torque of 23 cm / kg at 77.1 minutes. BeL another sample of the same basic formulation but with a content of 3 ^{parts by weight of N, N 1} -dicyclohexyl-p-phenylenediamine per 100 parts by weight of rubber hydrocarbon

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Mooney properties 27.6 minutes and 34.6 minutes for the two specified torque increases. The reduction in processing time is also achieved through incorporation of 1.5 parts by weight of N-phenyl-2-benzothiazolesulfenamide per 100 parts by weight of rubber hydrocarbons in fle Rubber mass balanced.

Example 7

Natural rubber was mixed in a conventional manner in such a way that it contains 3 parts by weight of N-phenyl-N '- (1,3-dimethylbutylp-phenylenediamine) and 1.25 parts by weight of N-p-methylphenyl-2-benzothiazole sulfenamide contained per 100 parts by weight of rubber hydrocarbon. The rubber was against breakage protected under the influence of ozone and at the same time had a higher Mooney Scorch value.

Example 8

This example illustrates the use of N-p-methoxyphenyl-2-benzothiazole sulfenamide as a processing time extender in nitrile rubber. The nitrile rubber was made mixed in a conventional manner such that it contains 3.5 parts by weight of N-phenyl-N '-sec-octyl'-p-phenylenediamine and 1.25 parts by weight of N-p-methoxyphenyl-2-benzopthiazolesulfenamide contained per 100 parts by weight of rubber hydrocarbon. Here again the rubber was against breakage protected as a result of the action of ozone and had a longer processing time.

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Claims (8)

- 18 claims 2U5110 Ij)) A method for compensating for a decrease in the processing time when a phenylenediamine antiozonant is added to a rubber material, characterized in that an N-aryl-2-benzothiazolesulfenamide is incorporated into the rubber material. 2.) Process according to Claim 1, characterized in that the sulfenamide is used in a concentration of about 0.5 up to about 3 parts by weight per 100 parts by weight of the rubber. 3.) Method according to claim 1 and 2, characterized in that that the sulfenamide is N-phenyl-benzothiazole sulfenamide used. 4.) Method according to claim 1 and 2, characterized in that that as sufenamide N-p-methylphenyl-2-benzothiazole-. sulfenamide or N-p-methoxyphenyl-2-benzothiazole sulfenamide used. 5.) Process according to claim 1 to 4, characterized in that the antiozonant is a Η, Ν'-di-sec-alkyl-p-phenylenediamine with 3 to about 20 carbon atoms in each alkyl group, preferably IT, N ¹ -di sec-octyl-p-phenylenediamine, or an N-phenyl-N'-sec-alkyl-p-phenylenediamine with 3 ' 309812/1012 _ ₁₉ _ ■ 2U5110 up to about 20 carbon atoms in each alkyl group, preferably II, N'-di-cyclohexyl-p-phenylenediamine is used. 6.) Process according to Claim 1 to 5, characterized in that the rubber used is butadieh-styrene copolymer, rubber, Natural rubber or nitrile rubber used. 7.) Vulcanizable synthetic or natural rubber, instes special diene hydrocarbon material or nitrile rubber material, characterized by the content of a combination of a phenylenediamine antiozonant and one li-Aryl-2-benzothiazole sulfenamide. 8.) Rubber according to claim 7, characterized by the content of a W-Zs.ryl-2-benzothiazolesulfenamide, in which the aryl radical a phenyl radical, an i-lower alkoxyphenyl radical Is chlorophenyl, a mono- or dialkylphenyl, the alkyl groups each having 1 to 6 carbon atoms contain. 309812/1012