DE2752345A1 - USE OF DIPHENYLAMINE AND CYCLOHEXANONE CONDENSATION PRODUCTS AS ADDITIVES TO ELASTOMERS - Google Patents

Description

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1A-50 086

Applicant: 30ZETT0 IWDU3TRIE CHIMICHE S.p.A. Via Mazzini 11 - PEDIlENGO, Italy

Title: Use of condensation products from diphenylatin and cyclohexanone as an additive to elastomers

809822/0798

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1-50 086

Applicant: Bozetto Ind,

description

The invention relates to the use of a condensation product of diphenylarain and cyclohexanone as Additive to elastomers and a process for their production. The condensation product according to the invention causes neither a Discoloration or staining and prevents both oxidation and damage during use, especially when bending the Elastoraermassen, v / ie e.g. 1,4-cis-polyisoprene rubber of natural or synthetic origin, butadiene-styrene rubbers (SBR), polybutadiene, polychloroprene or nitrile rubber (ITBR) and unfolds its effect on other polymers that are damaged or even damaged under the influence of oxygen disintegrate.

In the rubber and rubber industry, those are associated with the aging, discoloration and staining of rubber goods Problems and the need for good flexural strength in such articles are all too well known.

There is therefore a whole range of additions that can be used to circumvent or correct these difficulties tried, but such additives should be effective both before and after vulcanization and should also be effective if at all possible to develop a multiple effect, i.e. they should deal with several of the difficulties mentioned above at the same time.

—3—

809822/0798

It has now been found that this problem has been largely achieved is made by the product of a condensation of diphenylamine and cyclohexanone, which is suitable as an additive to the elastomer, to at least alleviate the difficulties mentioned.

The condensation of diphenylamine with cyclohexanone is carried out according to the invention at 130-160 ⁰ C to obtain aromatic solvents are hydrocarbons such as toluene and xylene, and used as a catalyst iodine or strong organic or inorganic acids, such as benzenesulfonic acid, p-toluenesulfonic acid or hydrochloric acid. The water released during the condensation is continuously distilled off. The reaction takes about 2 to 6 hours, after which the reaction mixture is washed out with hot water to remove the catalyst. After the aqueous layer has been drawn off, the organic phase is distilled in order to recover the solvent and the unreacted reactants; one works under a vacuum of 2 to 3 mm Hg at temperatures between 200 and 230 C.

The residue obtained in the present invention to be used as a condensation product Peststoff of ocher-brown color, which melts between 65 and 95 ⁰ C, with the precise melting point by the applied Reaktionsbeuingungen directed; the diphenylamine content is less than 0.5 '/ ό. The pick-up ratio of diphenylamine to cyclohexanone was varied between 1: 1 and 1: 2, and all pollen products were obtained which had extremely good antioxidant properties.

The condensation products were used both as additives for non-vulcanized or cured elastomers and for vulcanized or cured elastomers were tested, the latter containing the other additives customary for rubber.

809822/0798

-'s

The tests with non-vulcanized natural rubber were carried out using the oxygen absorption method. The mixture of elastomer and antioxidant, dissolved in a suitable solvent, is placed in a vessel filled with pure oxygen, in which the same pressure as in the environment is harsh and heated to a predetermined temperature. The oxidation process is followed by measuring the amount of oxygen absorbed during the test, which leads to an "induction time" which is characteristic of the particular antioxidant; The induction time is the time that elapses between the introduction of the sample into the oxygen atmosphere and the point in time at which the oxygen absorption reaches its greatest speed. In these experiments, the condensation product of diphenylamine and cyclohexanone proved to be extremely suitable for increasing the heat resistance of the rubber or gum; It was clearly superior to 2,2,4-trimethyl-1,2- ^{dihydroquinoline polymer, while it was at least as good as 2.2 l} -ethylene-bis- (4-methyl-6-tert-butyl) -phenol in non-vulcanized elastomers clearly superior to vulcanized or hardened elastomers.

The testing of the present condensation product as an antioxidant for vulcanized elastomers, which contained the usual additives for rubber, was carried out by measuring the parameters elongation at break, tensile strength and hardness as well as by determining the modulus at 200 ^ and 300 ° elongation _; which corresponds in each case to the force that is necessary to stretch the specimen by 200 or 300%; the liessungen performed respectively before aging and after aging 4-41 days in an air oven at temperatures of 90-120 ⁰ C and in an oxygen bomb at a pressure of 21 At.und 80 ⁰ C over a period of 2 days.

Comparative tests were carried out between Hishungen, which contained the condensation product of diphenylamine and cyclohexanone in various proportions as an antioxidant

809822/0798 _K

-5-

on the one hand and mixtures which either contained no antioxidant at all or, as an additive to prevent oxidation, polymers of 2,2,4 · trimethyl-1,2-dihydroquinoline, phenylbetanaphthylamine or H-isopropyl-N ¹ -phenyl-p.phenylenediamine.

The present condensation product of diphenylamine and cyclohexanone has proven to be an excellent antioxidant, especially for vulcanized elastomers; in particular, for the test pieces containing this additive, the decrease in tensile strength both before and after aging in the air oven and in the oxygen bomb was significantly less than that of the test pieces which did not contain any antioxidant. An effect of the same order of magnitude and often even more pronounced was observed compared to comparison samples which contained the known additives 2,2,4-trimethyl-1,2-dihydroquinoline, phenylbetanaphthylamine and isopropylphenyl-p.phenylenediamine. In the case of vulcanized guami mixtures, the good flexural strength brought about by the additive according to the invention corresponded to that which can also be achieved with the aid of trimethyldihydroquinoline polymer. The condensation product according to the invention has no influence whatsoever on the vulcanization or hardening process as such.

The invention is illustrated by the following examples, four of which relate to the preparation of the condensation product to be used according to the invention from diphenylamine and cyclohexanone and eight others relate to its practical use as a component of rubber mixtures which tend to disintegrate in the presence of oxygen and air , relate. The tests carried out in the oxygen bomb (BO) correspond to the regulation according to ASTI-I D 572 or AS ¹ IH 1865, the test of the mechanical properties (strength) was carried out in accordance with ASTH D 412.

- ■ 6-809822 / 0798

example 1

A reactor equipped with devices for distilling off and recycling the solvent is charged with 80 ml of toluene and 169.2 g of diphenylamine (1 mol) and heated. When the diphenylamine has completely dissolved, 3 g of iodine (0.01 mol) are added and heating is continued with stirring. When a temperature of 140 ⁰ C is reached, 98.1 g of cyclohexanone (1 Hol) are introduced, which happens over a period of 2 1/2 hours, so that the temperature of the reaction mixture is kept at 140-150 ° C. After all of the cyclohexanone another hour long is further heated to 145- 150 ⁰ C. During the reaction, which took a total of 3 1/2 hours, 18 g of water of condensation were then distilled off. The mixture is then ^{cooled to 90 °} C., whereupon 100 ml of toluene are added to it again and it is washed four times with warm water in order to remove the hydrogen yogic acid formed. The toluene and the unreacted cyclohexanone and diphenylamine are then distilled off from the reaction mixture, which is carried out under a reduced pressure of 2 mm Hg at a temperature of 220 ^° C. in the boiler and 180 ^° C. at the top. The residue was dissolved in this Pail 206 g of condensation product of diphenylamine and cyclohexanone as a tan solid which melted between 83-94 ⁰ C, obtained.

Example 2

According to Example 1, a Roaktor was charged with 80 ml of toluene and 169.2 g (1 mol) of diphenylamine. After heating and dissolving the diphenylamines 5 g '.0,01 mol) iodine were added and heating was continued with stirring until such time as the temperature was 140 ⁰ C. Then in this case 147.2 g (1.5 Hol)

-7-

809822/079 8

2 7 5 2 3 Λ 5

Cyclohexanone were added in 3 hours and the Reaktionsgetaisch kept another hour under reflux to 150 ⁰ C. 26 g of water of condensation distilled off and collected. After cooling the mixture to 90 ° and adding 100 ml of toluene, the reaction mixture was washed out and distilled as in Example. As a residue, 270 g of the condensation product obtained in this Pail, the melting range of 70 - was 80 ⁰ C.

Example 3

The procedure was as in Example 2, except that the iodine as a catalyst was replaced by 4 g (0.023 mol) of p-toluenesulfonic acid. In addition to 24 g of water of condensation, 202 g of condensation product with a melting range of 67-79 ° C. were obtained.

Example 4

In a reactor as above, 80 ml of toluene and 169 g (1 koi) Diphenylarain were heated to 60 ⁰ C, after which 5 g (0.01 mol) of iodine were added. The mixture was ^{then heated further to 140 °} C. and the addition of cyclohexanone was started, of which 196.3 g (2 hol) were added over the course of 3 hours. ! laughing hour '.7eitererhitzen to about 150 ⁰ C 34 g Synthesis of water were deposited. After cooling to 90 ⁰ C and addition of 50 ml of toluene, the mixture was washed four times / ater washed with hot V. The distillation was the product of Example 1.Es were obtained 300 g of an at 75-73 ⁰ C melting product.

Example 5

There were four solutions of rubber in 1,2,4-trichlorobenzene prepares, of which one 2/5 is natural rubber and the three another an additional $ 0.2 (based on the rubber content) one Contained antioxidant. AIg antioxidants were added to the product

809822/0798 " ⁸ "

According to Example 1, the 2,2,4-triraethyl-1,2-dihydroquinoline polymer and the 2,2 »ttethylene-bis- (4-methyl-6-tert-butyl) -phenol were used. 20 g each of the four solutions were then used subjected to the oxygen absorption test at 170 ^° C., the following induction times being measured:

Antioxidant induction time

without 87 min

Product au3 example 1 166 "

Trimethyldihydro

quinoline polymer 146 "

2,2-ethylene bis (4-methyl-
-6-tert-butyl) phenol 167 "

As can be seen, the condensate according to the invention turned out to be ious product of diphenylamine with cyclohexanone in the applied Concentration as a good antioxidant that was left over from the riraethyldihydroquinoline polymer for non-vulcanized natural rubber.

rubber mixtures of the following composition were used prepares:

Fitted parts

ITatur!: Ouchuk 100.00

ZuO 5.00

Stearin 2.00

ISAP carbon black 45.00 Schv; efol 2.00

ir-Cyclohexyl-2-benzthiazylsulfonamide 0.80

Heramid-D (Bozetto) 0.40

Antioxidant 1.00

809822/0798

In comparison with tin, the antioxidant was omitted in one of the mixtures, while the product from Example 1 (abbreviated to Pr.Ex. 1), the product from Example 2 (Pr.Ex. 2), the product from Example 4 as a component of the other mixtures (Pr.Ex.4), trimethyldihydroquinoline polymer ( ¹ J] DGt-PoI.), Phenyl-A-naphthylamine (PBIi) and K-isopropyl-K'-phenyl-p.phenylenediaain (IPPD) were used. The rubber mixtures were vulkanisie 12 minutes at 150 ⁰ C: After four days aging ia air oven at 9O ⁰ C, the various vulcanized blends had the following mechanical properties:

Table I.

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809822/0798

Tabeele I

Antioxidant elongation

tion in

^c / o

Decrease in i »

Tensile strength in

Decrease i /

in

^c / o

module

at 2Q0? S expansion. at 3 kg / m ^ kg / mm

£ stretch

without 195 (490) Pr. Ex., 1. 360 (500) Pr. Ex, 2 380 (525) Pr. Ssp. 4 " 355 (505) TDQ * oil. 345 (490) PBN 275 (510) IPPD 310 (495)

-60

-28 • 28 ■ 30

_: 30 -46 -37

0.48 (2.76) -83

2.01 (2.76) -27

2.06 (2.88) -28

1.83 (2.79) -34

1.90 (2.77) -31

1.06 (2.93) -64

1.60 (2.86) -44

- (0.66)

0.90 (0.67)

O.83 (O.6S)

0.85 (0.67)

0.89 (0.68)

0.68 (0.73)
0.87 (0.72

- (I.36) 1.62 (1.33) 1.5 3 (1.35) 1.49 (1.34) 1.62 (1.36)

- (1.40) 1.54 (1342)

Nachdera the samples in oxygen bomb for 48 hours at 21 at 80 ⁰ C and aged v / arene, some vulcanized blends had the following nechanischen properties:

Table II

Table II

Antioxidant elongation at break in ^c / o

Decline Zugfestigin ^c / 3 speed in kg / mm ^

decline

in

module

at 2OO7O stretch, kg / ατα ²

at 3QO; j stretch, kg / πα

8098 without :
Pr. Ex. Prob
1 e Deία λ
440 ltern λ zeriaj -27 IZZ \ Pr. Ex.
Pr. Ex. 2
4th 435
440 -29
-34 O 4? ^γ ϊ -23 CO
OO PBlT 445 -31 IPPD 410 -23 in heat
-12 Lien.
2.02 -17
-13 2.05
1.83 -11 2.14 -13 2.02 -17 2.19

0.71 0.67 0.63 0.77 0.71 0.34

1.28 1.26 1.14 1.39 1.27 1.52

From the tables it can be seen that the condensation product of diphenylamine with cyclohexanone for Ilaturkau-cschuk is a particularly good antioxidant and that its effectiveness, especially after jdea ^ Aging in the air oven is not less than that of TDQ-PoI, of ΡΒ1Ϊ and of IPPD.

Example 7

3 mixtures "were prepared, which were composed as follows v / aren:

Parts by weight Natural rubber 100.00 stearin 1.00 ZnO 5.00 45.00 sulfur 2.50 Mercaptobenzthiaal disulfide 1.00 antioxidant 1.00

For comparison, a mixture containing no antioxidant, whereas the other "contained both the product of Example 1 and a TDQ polymer. The mixtures were then 15 minutes at 150 ⁰ C vulkanisiert.Nachdem they have been kept in the 6 position luftofon at 90 ⁰ C were, the 3 vulcanized mixtures had the mechanical properties given in Table II (the original values are given in brackets in the table).

Table III

809822/0798

Table III

Antioxidant Brmhdeh- decrease tensile strength- decrease hardness hardness-

voltage in ^ fo in speed in in ^c / o (Shore A) Modified

kg / ma

without 165 (430) -66 0.62 (2.01) -69 62 +5

Pr. Ex. 1 265 (515) -49 1.76 (1.96) -10 70 +12

Q IDvi-Pol. 265 (500) -47 1.79 (2.07) -14 68 +11

⁰⁰ After the samples had been kept in an oxygen bomb at 21 atm and 80 ⁰ C for 48 hours, the above fourth v / ie had changed as follows:

^? Sample from ν

co example 1 475 -8 1.66 -15 59 +1 IJ =

TQO-PoI. 455 -9 1.72 -17 60 +3 '

Example 8

Two mixtures of the following composition were made:

Parts by weight cis-polybutadiene ("Europrene eis)" 100.00 soot 40.00 ZnO 3.00 stearin 2.00 sulfur 1.80 If-cyclohexyl-2-benzthiazylsulfenamide 0.80

A mixture containing no antioxidant, whereas the other is a G-ewichtsteil of the product was added to Example 2, iTach 8 Hinuten long vulcanizing at 165 ⁰ C and 26 Sage lasting aging in the air oven at 90 ⁰ C had the two samples of vulcanized mix the Mechanical properties listed in Table IV (the original parameters are in brackets):

Table IV

τ a ρ e χ ± e iv

Antioxidant elongation at break decrease tensile strength- _? decline

in 5i in # kg / mm in %

without 30 (225) -87 0.19 (0.69) -72

Pr.Ex.2 65 (235) -72 0.49 (0.68) -28

Example 9

3 mixtures with the following composition were prepared:

809822/0798 " ¹⁵ "

Parts by weight

Hitrile rubber ('Europrenc LJLT') 100.00 soot 40.00 ZnO 5.00 stearin 1 .00 sulfur 1.50 Mercaptobenzthiasol disulfide 0.50 antioxidant 1 .00

jjie comparison sample was again without an antioxidant while the other two mixtures contained the product from Example 2 and IPPD as antioxidants. laugh Vulcanizing at 150C for 20 minutes and 41 days Aging in an air oven at 90 ° the samples had the mechanical properties listed in Table V, with the original fourth are again listed in brackets.

Table V

Antioxidant Elongation at break decrease in tensile strength decrease in ⁰ Jo in ) ό kg / mm in ', &

without
Pr. Ex.2
IPPD 100 (405)
190 (425)
215 (495) 10 -75
-55
-56 0
1
1 .80 (1,
.72 (2,
.91 (2. -59
-15
-15 example became two It
rode: Mixtures following .95)
.02)
.26) Composition

Parts by weight

Polychloroprene (neoprene W) 100.00

Stearic acid 809822/0798 0.50

Ituss 50.00

I-lgO 4.00

ZnO 5.00

Ethylene thiourea (Accelerator

JO 4022, Bozetto) 1.00

The comparison sample contained no antioxidant ^ during the other mixture 1.0 parts by weight of the product from Example 2 were added. Wake up vulcanizing for 15 minutes 150 ° and aging in an air oven at 120 ° for 7 days If the samples had the mechanical properties listed in Table VI, the original data in Brackets are listed:

Table VI

Antioxidant elongation at break decrease in tensile strength decrease in fi in ° /> kg / mm ² in fi

-94 0. 92 (2 .01) -54 -52 1. 60 (2 .11) -24

without 20 (360)

Prod. From example 2 185 (585)

After aging in the oxygen bomb (4 days at 8O ⁰ C), the values were amended as follows:

without 210 pr. ex. 2 545

-42 -10

0.75
1.52

-62 -28

Example 11 prepares:

UBiI 1712
ZnO

Stearic acid carbon black

There were two mixtures of the following composition

Parts by weight

157.50

5.00

1.00

60.00

809822/0798

-17

- vr-

aromatic Ul (IiUtI ¹ Qx 729) 10.C0

Sulfur 1.üO

ii-Cyclohexyl ^ -bonzthiazylsulfenataid 1.20

While no antioxidant was added to the comparative sample, a weight-bearing product from Example 2 was added to the other. Ka ca mandrel 20 I-Iinuten continuous vulcanization at 165 ° G and aging in the air oven (21 days at 100 ⁰ G) had the two mixtures, the mechanical properties listed in '±' abelleVii_, whereby the original 7 / erte are shown in parentheses :

T a b ο 1 1 e VII

Antioxidant elongation at break decrease in - / j in / i

Tensile strength decrease kg / mra in , Ό

without 175 (7 ^ 0) -77 1.11 (1.97) -44

Pr.Bsp. 2,218 (725) -70 1.08 (1.77) -33

Example 12

There were two mixtures of the following composition prepares:

Weight parts

cis-polyisoprene ("Euro prene IP 80 ") 100.00 Stearic acid 1 .00 ZnO 5.00 soot 45.00 sulfur 2.50 Mercaptobenzthiazole dis sulfide 1.00

While an antioxidant was added to the comparative sample, one part by weight of the product from Example 2 was added to the other sample. After curing (15-I iinuten at 150 ⁰ C)

809822/0798

"« Is-

and aging in an air oven (6 days at 100 ° C) showed the vulcanized Mixtures have the mechanical properties listed in Table VIII, with the original values again in brackets

listed are: T a b e 1 1 e VII decline decline To{ in 'fo antioxidant Elongation at break in Io kg / -64 in , Ό -55 ^ strength -15 without 225 (495) -45 'mm Pr.Bsp. 2 296 (520) 0.81 (2. 1.98 (2. .23) .35)

809822/0798

Claims (4)

Claims 1. Use of condensation products from diphenylamine and cyclohexanone as an additive (antioxidant) that prevents oxidation by oxygen or air in rubber-like elastomers, 2. Use of condensation products according to claim 1 as an additive to 1,4-cis-polyisoprene, synthetic 1,4-cis-polyisoprene, Polybutadiene, styrene-butadiene rubber, nitrile rubber, etc. or polychloroprene. 3. Use of Konuensationsprodukte according to claim 1 or 2, which are prepared by a solution of Diphenylatnin and cyclohexanone, preferably iia molar ratio of 1: 1 to 1: 2, in an aromatic solvent in Gegenv / kind of iodine or a strong one ^{organic or inorganic acid as catalyst is heated to 130 to 180 °} C. for 1 to 8 hours while distilling off the water of condensation and the condensation product is isolated. 4. Use of condensation products according to claim 1 or 2, which is prepared according to claim 3 in the presence of paratoluene sulfonic acid, benzenesulfonic acid or hydrochloric acid as a catalyst. 809822/0798