DE1105604B - Process for the pretreatment of vulcanizable, filler-containing, synthetic rubber - Google Patents

Description

GERMAN

The invention relates to a method for the pretreatment of vulcanizable, filler-containing, synthetic rubber, which is obtained by polymerizing a predominant amount of olefin with a minor amount Amount of diolefin produced, e.g. B. butyl rubber, in the presence of an activator for the heat treatment, but without the addition of vulcanizing agents, at least not in such amounts as are necessary for vulcanization, this pretreatment in a heat treatment, either before mixing or kneading or at the same time, exists, but in any case before Complete mixing of the substance mixtures with vulcanizing agents, shaping and vulcanization.

So far, one used for the production of strong, tough and abrasion-resistant rubber mixtures as a reinforcing agent mainly soot, especially sewer soot. By adding it in amounts of, for. B. 50 kg to 100 kg In rubber, significant improvements in tensile strength, elastic modulus, and others have been achieved Properties of the resulting mixtures of substances after vulcanization. In particular, there were carbon black additives Natural rubber and highly unsaturated synthetic rubber are advantageous, e.g. B. with a copolymer of butadiene and styrene; however, if the channel black is simply admixed with the butyl rubber and the vulcanizing agents and subsequent vulcanization, the products obtained do not have good values for tensile strength and modulus that can be achieved with natural rubber.

Butyl rubber is a highly unsaturated synthetic olefin-multiolefin rubber with an iodine number according to Wi j s between about 0.5 and 50 and a molecular weight according to Staudinger of at least about 20,000. Its production has already been described in literature. As in four essays by A. M. Gessler in "The Rubber Age" described from October 1953 up to and including January 1954, recently succeeded Heat treatment of butyl rubber with sewer soot before adding vulcanizing agents and the Vulcanization significantly improves tensile strength and modulus.

It was hoped that a similar heat treatment would also produce strong, tough and elastic products from mixtures of synthetic rubber obtained by polymerizing a predominant amount of olefin and a minor amount of diolefin is produced, e.g. B. of butyl rubber, with inert mineral fillers, such as silica of various types and clays, would allow previously when admixed to this synthetic rubber only acted as an internal diluent. It turned out, however, that even when heat treating a mixture of z. B. 50 parts by weight of a silica or clay with 100 parts butyl rubber, at rest or under pretreatment procedures

of vulcanizable, filler-containing,

synthetic rubber

Applicant:

Esso Research and Engineering Company, Elizabeth, N.J. (V.St.A.)

Representative: Dr. W. Beil, lawyer, Frankfurt / M.-Höchst, Antoniterstr. 36

Claimed priority: V. St. v. America May 2, 1955

Hot kneading, but in any case with subsequent Treatment in one kneading stage, subsequent cooling, addition of vulcanizing agents and Vulcanization, the fully vulcanized products usually have little or no better tensile strength at all, Modules and dynamic properties showed.

It has now been found that a pretreatment of the abovementioned vulcanizable synthetic Rubber mixtures with improved physical properties in terms of strength and elasticity obtained when one of such polymers from a predominant amount of olefin and a smaller amount Amount of diolefin goes out whose molecular weight is at least 20,000 and whose iodine number is about 0.5 to 50, and these polymers are heated to 120 to 230 ° C after the addition of fillers, the specialty being that that the mixtures, the fillers of which are inert, in the presence of an organic heat conversion activator heated, consisting of an aromatic compound of the general formula

ρ - ON - Ar (R) ₄ - NR ' ₂

in which Ar is an aromatic nucleus and R and R 'are hydrogen, alkyl, aryl or other hydrocarbon radicals mean, or from a quinoid compound with at least one nitrogen- or oxygen-containing group exists on the ring, working under conditions in which vulcanization of the elastomer mixture is avoided. This pretreatment of synthetic rubbers with inert additives Although fillers alone do not improve the mixture, the addition of the heat treatment activator does before or during the heat treatment to ensure that the mixtures after the addition of customary

109 578/433

3 4

Vulcanizing agents and finished vulcanization considerably p-quinone dioxime di- (p-methoxybenzoate)

improved tensile strengths, moduli and dynamic p-quinonedioxime di- (n-amyloxybenzoate)

Have properties. p-quinonedioxime di- (m-bromobenzoate)

It has been proposed to use aromatic modified aliphatic esters

Treatment of rubber mixtures with carbon black initially 5 _,. ,. . ..,,,

in the absence of vulcanizing agents, the mixtures p-quinone dioxime di- (phenyl acetate)

to heat and thereby also mineral fillers metal compounds

to mix in. However, this known procedure resulted in the monozinc salt of quinone dioxime

No solution has yet been found for the problem at hand, the dicin salt of quinone dioxime

inert mineral fillers in such vulcanizable io zinc chloride double salt of quinone dioxime

Incorporate elastomers, the very little unsaturated mono-mercuric salt of quinone dioxime

Had bonds, and therefrom mixtures of high di-mercury salt of quinone dioxime

To maintain strength. Mercury chloride double salt of quinone dioxime

Also the replacement of the soot in the previously mentioned mono-barium chloride double salt of quinone dioxime

known mixtures by zinc oxide has with the 15 mono-copper salt of quinone dioxide

Addition of inert fillers such as silica, clay or the mono-lead salt of quinone dioxime

Silicates and the subsequent heat treatment mono-barium salt of quinone dioxime

nothing to do with the additives according to the invention, because the silver salt of p-quinone dioxime
Zinc oxide is not an inert filler in the rubber

technical sense, but has itself certain 20 core changes

vulkanisationslösungen.de properties. 1,4-naphthoquinone dioxime

The addition, which has already become known, has just as little 2,6-dimethyl-1,4-quinonedioxime

various sulfur-free reagents as Vulkani- 2-Phenyl-1,4-quinonedioxime

sation agent for various synthetic rubber 2-benzyl-1,4-quinonedioxime

to do something with the present procedure. There 25 thymoquinone dioxime

This is because this is always only about the thymo-quinonedioxime dibenzoate

use of such additives for vulcanization itself. Thymo-quinone dioxime diacetate

In the present method, however, the. ,,,.,. _Λ7 v-,

..... ^. t ^ - j. ■ j · j. Various connections

Heat conversion activators only ever before the actual ...

lent vulcanization, so not under vulcanization 30 "Phloroglucin-tnoxim

conditions, heated together with the rubber. 2, S-dimtroso-4-isopropyltoluene

One of the substances that is very useful as an activator is p-dimtrosobenzene

have been shown to be p-nitroso-dimethylanuine. This m-dinitrosobenzene

Compound has the formula Chmon-bis-chlonmm

_nv r ν υ, γηι 35 2,4-dinitro-1-naphthol

ρ υ λ · C ₆ ^ n ₄ · λ (C ± 1 ₃ ) ₂ 2,6-dichloroquinone-monochlorimine

Other related compounds have the same effect.

the general formula activator varies between about 0.1 and 5 parts,

ρ o \ · Ax (R) · \ R preferably 0.5 to 2 parts, per 100 parts by weight of the

40 polymer, ie butyl rubber. The to Erin which Ar has an aromatic nucleus, e.g. B. of benzene, the most favorable results required amounts of naphthalene or anthracene, and R is hydrogen, of the activator are generally proportional to an alkyl, aryl-alkaryl or aralkyl group. Amount of fillers.

Dibenzoquinone dioxime is a preferred activator. It has been used as butyl rubber for a number of years

Also take other organic compounds with a 45 commercially available type that have a high molecular weight

aromatic or Chinoidaufbau are useful lares copolymer of about 90 to 99.5 ° / ₀ isobutylene

if an NO is preferably bonded to their ring, and about 10 to 0.5% isoprene, which is commercially available

z. B. p- or m-dinitrosobenzene, quinone dioxime and available product in general the narrower range

Derivatives of these compounds, e.g. E.g .: from about 95 to 99% isobutylene together with 5 to 1 ° ₀

Aliphatic esters of p-quinonedioxime derivatives 5 <> Includes isoprene. The Staudinger molecular weight

p-Quinonedioxime diacetate ⁸ ^ ™ ^ 5 ¹ ^ ^{113 2} ° °°° ' ^v ° ^r _T ^z ig3weisemmdes _te n _S 30,000

ρ quinone dicaproat ^{or 40} ° ^{00 'Betra} g ^s · and can be up 100,000 or more

p-quinone dioxime dilaurate ^w f are higher. The Mooney value (8 minutes at 100 = C)

p-quinone dioxime distearate ^5θ11 ^ at least about 30, for best results

p-quinone dioxime dicrotonate ⁵⁵ ™ ^{d lei} for machinability but preferably between

p-quinonedioxime dinaphthenate ⁴⁰ ™ ^d f . The production of butyl rubber, which is not protected here, can also be used

Use other equivalent monomers (with aliphatic dibasic acids). Instead of

p-Quinonedioxime succinate of isobutylene can also be used, for. B. methyl

p-Quinonedioxime adipate 60 2-butene-1 or any other olefin, preferably

Furfural ^e i ⁿ isoolefin having from 4 to 8 carbon atoms, take.

p-Quinonedioxime-di-furancarboxylic acid ester ^{Instead of v} ™ } ^so f ™ ^can "fn ^ h of other conjugated multiolefins with 4 to 14 carbon atoms

Aromatic esters start, preferably from conjugated diolefins with

p-quinone dioxime dibenzoate 65 4 to 6 carbon atoms, e.g. B. of butadiene, piperylene,

p-quinonedioxime di- (o-chlorobenzoate) dimethylbutadiene or 2-methylpentadiene.

p-Quinonedioxime p-chlorobenzoate Among those which can be used according to the present invention

p-quinonedioxime di- (p-nitrobenzoate) mineral fillers do not belong to those made from carbon black

p-quinone dioxime di- (m-nitrobenzoate) existing fillers or pigments, such as the oxides,

p-quinonedioxime di- (3,5-dinitrobenzoate) 70 hydroxides or carbonates of silicon, aluminum,

5 6

Magnesium or titanium or their silicates or aluminates. from 1 to 2 parts of sulfur to 100 parts of rubber,

Examples of different mineral fillers are: take. In addition, about 0.5 to 2% accelerator can be used

_A1 . . .,.,. _nt .. ", n / r · Ui can be added, e.g. B. tetramethyl thiuram disulfide,

Aluminum silicate precipitated magnesium carbonate _o ? _T. , ,, ·, τ> ,, -, _, · _{1CJ π} · λ - · α.ι_ ι

" _R , ,,. ..,? , 2-mercaptobenzothiazole, benzthiazyl disulfide, bis-4-ethyl

Water containing various. .,. ,,. _{1 £} , · “. ,,.,. ^ _π . ,,,, ../

Aluminum silicate SiO ₂ : Al ^ ^{ratios 5} toazyl disulfide, diphenylguanidine, butyraldehyde-anilm-

Precipitated Precipitated hydrated condensation product zinc dimethyldithiocarbamate

Calcium carbonate calcium silicate and ° ^ other thiurams, Drthiocarbamate.Thiazolguanidme

Basic. -metasilicate λ c * π j ' u j τ, ± e τ. c -ι

., . . _lx . τι j j. · · j. Tr- ι ·· Instead of or in addition to the abovementioned sulfur

Aluminum sulfate Hydrated silica, _A ",,. . uu χ «·

.,. . ,, A Λζ \ "& λ ^{10 to} ß ^esc hleumger can also be sulfur-free

"Y j ■ _ S vulcanizing agents, such as p-dinitrosobenzene, p-quinone

Bauxite titanium dioxide,. . -, ~,. ' K _11,, . . , ^

",. _, ^J dioxim or rhiuramtetrasulfide, add.

" ^{Ao m} . ν, ° ^{ner e} ^ ^e t In addition, to the mixture prior to the vulcanization ° sation enforce other conventional ingredients such. B. These various mineral fillers should be antioxidants or other stabilizers, fine-grained powders with a fineness of 99% stearic acid (about up to 2%), zinc oxide (about up to 25%), 0.044 mm and their overall particle size desired color pigments or colors and cut down to 0.01 to 0.02 μ. The amount, if necessary, either small amounts (e.g. 1 to 10%) of the mineral fillers to be added depends on waxes, resins or oils as processing aids according to the intended use of the finished 20 or even larger amounts (about 10 to 50%). Mixtures of substances and according to the various desired volatile mineral oils or esters as extenders, physical properties, however, should normally after incorporation of the desired vulcanization between about 10 and 200, preferably about 50 and 100 agents and other additives, the mixtures receive the or 150 parts by weight of the mineral fillers to desired final shape and will ultimately be 100 parts by weight of the rubber (abbreviated%). 25 vulcanized.

For example, for electrical insulation, the mixtures according to the present invention are also

quite a large amount of mineral fillers, e.g. B. usable as a binder, d. H. in the form of dispersing

about 80 or 100 to 150%, may be desirable. Similar high sions of the activated and heat-treated mixture

Additives can be used to make various types of from butyl rubber and the mineral fillers in

Molded rubber articles may be useful at a concentration of about 5 to 40 percent by weight

z. B. for seals, tapes or floor coverings. When in a volatile solvent such as gasoline, alone or

Mixtures for the manufacture of vehicle tires with together with vulcanizing agents,

white walls, however, should be the amount of white. .

The filler is generally about 50 to 100%. example 1

The mixtures of butyl rubber, mineral 35 To demonstrate the use of an activator

Fillers and activators according to the present invention during the heat treatment of butyl rubber

can either be static (i.e. at rest) or obtainable benefits has been shown in a number of attempts

dynamic, d. H. under mechanical working through, a calcium zeolite filler with an average

be heat treated, e.g. B. carried out by hot kneading, or particle size of about 0.01 to 0.05 μ. For

alternately static and dynamic or under 40 of these attempts, a commercially available synthetic

static circulation treatment with regular under-table isobutylene-isoprene rubber with a Mooney

breaks, during which brief kneading treatments are worth (8 minutes at 100 ⁰ C) from about 61 to 70, the too

are switched on. Temperatures of heat- about 1.5 to 1.7 mole percent unsaturated. How out

Treatment should be between 120 and 230 ° C, as shown in Table I, was used in these five experiments

between 150 and 200 ° C, with the hand- 45 p-nitroso-dimethylaniline in amounts of 0.5 to 4%

The duration of the treatment is inversely proportional to the temperature and, in another experiment, 0.5% p-dinitrosobenzene

fluctuates: about 1 hour to 8 hours when used as an activator.

at 120 ° C in the resting state he warms up, up to 5 to 30 minutes For comparison, two tests were also carried out without at 175 to 230 ° C with warm kneading (heating in the activator, one with the same Barnbury or with a different dynamic heating), Go heat treatment as in the above-mentioned experiments. Combinations between these values and the other without heat treatment at all, of temperature, time and kneading or other workings are possible for the six types of work carried out with activators. Experiments and the one without activator applied Regardless of how the mixtures of butyl heat treatment consisted of one hour of warm rubber and mineral fillers hot- 55 kneading at 155 to 160 ⁰ C. The composition of the treatment, ie, whether static or under hot for all seven heat-treated and one attempt kneading or by another kneading treatment, should the mixture used without heat treatment, the heat treatment was in each case with one of the following:

Closing kneading or mixing treatment ends to make butyl rubber 100

to be sure that the mixture is homogeneous and in 60% stearic acid

a smooth, easily machinable, plastic state calcium zeolite 80

is located. Then you should apply the mixture to below heat treatment activator (see Table I)

120 ⁰ C to cool or allow to cool down when adding the

Vulcanizing agents to prevent scorching; After the hot kneading, the samples were approx then the desired vulcanizing agent 65 is added, cooled to 43 ° C. and mixed with it at about 43 ° C.

with mechanical mixing with the proportionally following accelerator mixture added:

moderate temperature, e.g. B. at about 37 to 12O ⁰ C, ZnO 5

preferably at 37 to 65 ° C. Sulfur 2

For butyl rubber you can use the usual vulcani- tetramethyl-thiuram disulfide 1

Sating agent in amounts of about 0.5 to 3, preferably 70 di-2-benzothiazyl disulfide 0.5

The samples were then cured for 8, 16, 32 and 64 minutes at 160 ° C and their physical

and electrical properties examined; the results are given in Table I below:

Table I Physical Properties

Tensile Strength, kg / cm ² - Elongation,%

Module at 100 to 200% 1 ₈ _ _Shore . _hardness

Module at 300 to 400 <% j ^{kgl Cm bhore Marte}

Parts of the ί ⁰ I. ο. ί 0.5 ■ ί 1 ί 1.5 I. ² 1 4 - 101.2 - 8th 98.4 - Vulcanization time at approx 66 95.6 - 690 56 91.4 - 160 ° C - 67 85.1 - 64 attempt Acti ί ί 7.0- 760 9.8 - 11.2- 15.5 11.2- 11.2 - 660 No. vators ί 0.5 y 19.7 - 11.9 26.0 - 16 29.5 - 33.0 28.1 - 32 25.3 - 17.6 i / o 30.9-63 680 Heat treated 660 53 101.9 - 670 36.9-68 73.9 - 85.8 - 17.6 20.4 14.1 - 19.0 91.4 - 1 7.7- 810 9.8- 40.1 - 47.8 - 38.0 - 42.9 12.7 - 640 16.2 - 11.2 23.9 - 590 52 100.9 - 30.2 - 21.1 89.3 - 23.9 101.2 - 28.8 15.5 - 660 - 57 98.4 - 42.9 10.5 - 690 11.9- 64.0 - 47.1 - 18.3 14.8 - 580 2 26.0 - 17.6 31.6 - 520 50 102.7 - 39.4 40.8 - 27.4 98.4 - 12.2 101.2 - 30.9 16.2 - 620 - 54 101.9 - 57.6-62 11.9- 600 14.1- 70.3 - 50.6 - 24.6 16.9 - 550 3 39.4 - 24.6 45.7 - 550 52 103.4 - 54.1 50.6 - 32.3 103.4 - 57.6 98.4 - 31.6 14.1- 560 - 52 104.1 - 71.0-56 11.9 - 590 14.8 - 76.6 - 51.3 - 30.9 16.9 - 520 4th 43.6 - 26.0 49.2 - 480 50 73.8 - 66.8 54.8 - 34.4 101.9 - 63.3 106.1 - 34.4 14.8 - 550 - 51 100.5 - 77.3-53 11.2 - 580 14.1 - 67.5 - 49.2 - 32.3 14.1 - 530 5 44.3 - 24.6 55.4 - 650 99.8 - 73.7 251.4 - 33.0 71.0 - 64.7 78.0 - 21.1 12.7 - 550 - 52 74.5 - 75.2-53 11.9 - 500 14.8 - 46.7 - 36.9 - 30.9 14.1 - 490 6th 42.9 - 27.4 51.3 - 75.2 49.2 - 32.3 83.7 - 57.6 93.5 - 480 - 54 101.2 - 63.3-53 8.4- 740 11.9 - 31.6 14.1 - 620 7th 22.5 - 14.1 31.6 - 63.3 38.7 - 24.6 33.0 630 55.5-53 23.2 8th 51.3

In experiments 3 to 7, p-nitroso-dimethyl-aniline was used as the activator, whereas in experiment 8, p-dinitrosobenzene was used.

Electrical Properties

attempt Parts of the Xr. vators 1 0 2 0 3 0.5 4th 1 5 1.5 6th 2 7th 4th 8th 0.5

Dielectric
constant
at 1 kHz

5.34
4.07
3.83
3.63
3.61
3.55
3.39
3.64

Power at 1 kHz

0.129
0.061
0.068
0.038
0.039
0.033
0.036
0.046

Insulation resistance

1.18 ·
2.94
4.1
1.17
3.39 ·
2.77-3.34
7.89 ·

10 ¹⁰ 10 ¹² 10 ¹³ 10 "10" 10 "10" 10 ¹³

The data in the table under the heading "Physical properties" show that as compared to the non-heat treated counterpart sample Nos. 1, the long at 32 and 64 minutes vulcanization, a tensile strength of 85.1 to 95.6 kg / cm ² and a Has a modulus of 25.3 to 29.5 kg / cm ² , in the case of the heat-treated control sample 2 without activator, which has a tensile strength of 91.4 and a modulus of 28.1 to 30.2 kg / cm ² , no significant improvement tensile strength or modulus has been achieved. On the other hand, achieved

the activated, heat-treated samples 3 to 6, in which 0.5 to 2 parts of p-nitroso-dimethylaniline were contained as activator, corresponding tensile strength between 98.4 and 105.5 kg / cm ² and, when using 0.5% activator, a Much greater increase in modulus up to 38.0 to 40.8 kg / cm ² , with the addition of 1 ° ₀ activator in sample 4 an increase in modulus to 47.1 to 50.6 kg / cm ² and finally with use from 1.5 to 2% activator for samples 5 and 6 an increase in modulus to 50.6 to 54.8.

Sample 8 is similar to sample 3, with the exception that _{it contained p-dinitrosobenzene as an activator (in a concentration of 0.5 ° 0} ) instead of p-nitroso-dimethylaniline. With p-dinitrosobenzene as the heat treatment activator, tensile strengths of 99.8 to 101.2 kg / cm ² and at 300% a modulus of 35.8 to 38.7 kg / cm ^{2 were achieved} , i.e. about the same increase as in sample 3 compared to the tensile strengths of 85.1 to 95.6 and the module 25.2 to 30.1 kg ^r cm ² in the comparison sample.

Under the heading »Electrical properties« show the heat-treated substance mixtures with activator additives all dielectric constants between 3.39 (experiment 7) to 3.83 (experiment 3), which are much lower than the value of 5.34 for the non-heat treated one

Counter sample 1 and the value 4.07 for the heat-treated comparison sample 2 without activator. The performance factors obtained according to the present invention also fluctuate between 0.033 (test 6) and 0.039 (test 5) in the case of the substance mixtures heat-treated in the presence of 1 to 4% activator. These values mean surprisingly large improvements over the 0.061 of the heat-treated comparative sample 2 without activator and the 0.129 of the non-heat-treated counter-sample 1. The addition of a smaller amount of 5% of the heat treatment activator (in experiments 3 and 8) resulted in significant improvements over the not heat-treated comparative sample 1. All heat-treated substance mixtures with activator additives had significantly better insulation resistances compared to the two comparative samples; the highest insulation resistances, namely between 1.17 · 10 ¹⁴ and 3.39 · 10 ¹⁴ , were shown by those samples (tests 4 to 7) in which at least 1% activator was contained. These numbers are approximately 100 times as large as the insulation resistance of 2.94 · 10 ¹² in the case of the heat-treated comparative sample 2 without activator and approximately 10,000 times as large as the value 1.18 · 10 ¹⁰ in the case of the non-heat-treated comparative sample 1.

Example 2

For the detection of a sodium montmorillonite in butyl rubber mixtures with activator additives If correspondingly large improvements were achieved, a further series of tests was carried out. This Additive has a fineness of less than 40 μ. This series of tests was based on the same composition as in the heat treatment experiments in Example 1, but with sodium montmorillonite instead of calcium zeolite.

For comparison, test 1 lacked heat treatment, while tests 2 to 6 included heat treatment. The heat treatment activator used was p-nitroso-dimethylaniline in amounts of about 0.5 to 4.0%, and the heat treatment in these experiments was carried out in eight stages, each with half-hour heating in steam at 165 ^° C. and after each stage, about 5 Minutes of kneading to improve the homogeneity and increase the heat treatment effect. In Experiment 7, it took 3 1.0% activator, such as in laboratory, but the heat treatment is another, namely a 1 hour Warmknetung at 155 to 160 ⁰ C.

After the heat treatment of the mixtures, they were cooled to below 43 ° C and then, as in Example 1 described, mixed with vulcanizing and accelerating agents at about 43 ° C.

The products were then vulcanized in the form of customary test plates and as in Example 1 examined their physical and electrical properties; the results are shown in Table II.

Table II

Heat treatment of butyl rubber with sodium montmorillonite. Physical properties

Tensile strength, kg / cm ² - elongation% modulus at 100 to 200% 1,. _a g, _H modulus at 300 to 400% > ^kglcm ~ ^ nore-Marte

Parts r 0 1 0.5 I. 1.0 I. 1.5 I. 4.0 1 1.0 16.9 - 8th -44 Vulcanization time at around 160 ° C 32 800 22.5 - 780 45.0 - 840 16.2 22.5 29.5 - 64 20.4 attempt Acti [ f r r 3.5 - Comparative sample 1 not heat treated 6.3 7.1 - 10.5 7.8 - 9.1 34.4-44 46.4-47 7.1 - 42.9-46 No. vator *) ( 2.0 \ 8.4 - 820 16.2 - 11.2 11.2 - 19.0-45 17.6- 14.1 660 690 11.2 - 840 610 ° / o \ 6.3 -46 3.5 - Heat treated 680 21.8 21.1 9.1 22.5 ί 24.6 - 10.5 16 9.8 - 16.9 680 47.1-46 40.1-47 52.0 - 14.1 45.7-46 7.1 - 37.3-45 11.9 96.3-690 720 8.4 - 640 1 11.2 - 800 -43 36.5 - 670 24.6-46 11.2 - 11.2 21.1- 670 22.5 66.8 - 8.4 7.1- 21.1 71.7-680 33.7 - 19.0-44 14.1 47.1-47 9.1- 14.8 14.1- 44.3-47 9.8- 101.2 - 28.8-46 660 23.9 - 700 -45 74.5 - 670 24.6 - 12.7 - 75.2-650 21.1 2 70.3 - 14.8 10.5 - 23.2 91.4 - 31.6 - 10.5 - 40.1-47 10.5 - 33.0- 26.0 - 47.8-47 11.2- 36.6 - 30.2 - 730 30.2 - 590 18.2-43 87.9 - 700 34.4 - 7.8 - 77.3 - 11.9 3 65.4 - 20.4 11.2- 20.4 15.5 - 11.2 - 20.4-44 10.5 - 42.9- 32.3 - 35.9-46 33.7 - 28.1 - 570 88.6 - 740 79.5 - 4th 92.8 - 19.0 10.5 - 11.2 11.2 - 10.5 - 37.3- 35.1 - 19.0-45 35.2 - 24.6 - 730 101.2 - 84.4 - 5 38.0 - 17.6 12.7 - 11.9- 7.7- 31.6- 28.1 - 29.5 - 14.1- 750 39.4 - 42.2 - 6th 10.5 8.4 - 7.7- 15.5 - 16.2 - 7th

*) See footnote to the second part of the table.

109 57S / 433

Electrical Properties

attempt Parts of the Tuesday
electrical Performance Isolating Xr. AKtI- constant ΙΕΐΚΐΟΓ resistance vators *) at 1 kHz at 1 kHz 1 0 5.28 0.017 6.2 -10 " 2 0.5 4.50 0.026 3.4 -10 ¹ * 3 1.0 4.48 0.025 4.82 x 10 " 4th 1.5 4.59 0.026 4.12 · 10 ¹⁴ 5 2.0 4.63 0.03 3.39 10 " 6th 4.0 4.70 0.02 4.22 · 10 ¹⁴ 7th 1.0 4.67 0.017 4.34 x 10 "

After the vulcanizing agents had been added to the basic mixtures, these were vulcanized for 16 and 32 minutes in the form of the usual test plates at 160 ^° C. and then examined for their physical properties, the following results being found:

IO

*) In experiments 2 to 7, p-nitrosodimethylaniline was used as the activator.

The data in Table II show that the non-heat treated mixture of 80 parts of sodium montmorillonite filler and 100 parts of butyl rubber when vulcanized for 32 minutes at 160 ^; C gave a very low tensile strength of only 22.5 and a very low modulus of only 11.2 kg / cm ² ; the mixtures of substances with the activator additives heat-treated according to the present invention, on the other hand, gave tensile strengths of 45.0 kg / cm ² (test 2) with the addition of 0.5 °, ' _o activator progressively up to 71.7, 91.4, 96, 3 and 101.2 kg / cm ² (experiment 3 to 6) with increasing amounts of the activator up to 4.0% and also correspondingly large increases in the modulus at 300% from 17.6 kg / cm ² in experiment 2 up to 34 , 4 in test 4 and very slight decreases to 33.7 kg / cm ² and 31.6 in tests 5 and 6. In this way, a mineral filler, which was previously worthless as a reinforcing agent for butyl rubber mixtures, was effective in achieving Tensile strengths and modulus are used which are several times the value of the corresponding numbers achieved but without the activated heat treatment according to the present invention. The electrical properties of these mixtures of butyl rubber and sodium montmorillonite are only slightly improved by this treatment.

Example 3

45

This example shows the modulus improvement achievable when the present invention is applied to mixtures of butyl rubber and an alumina mineral filler with an average particle size of about 0.01-0.02μ. 90 parts of this filler were mixed with 100 parts of commercially available butyl rubber with a Mooney value of 41 to 49 and 1.5 to 1.9 mol percent unsaturation, and with 1 part of butoxyethyl diglycol carbonate as an agent to prevent sticking to the mixing roller and 2 parts of stearic acid as Plasticizer mixed. In this way, two identical basic mixtures were prepared, one of which was treated as a comparative sample without the action of heat, while 1.5 parts of p-nitroso-dimethylanine were added to the other as an activator for the heat treatment and then kneaded at 125 ° C. for 15 minutes. The mixture was then cooled to around 43 ^° C. and a vulcanizing agent mixture of the following composition was added to the two basic ^{mixtures at around 43:> C:}

ZnO 5

Sulfur 2

Tetramethyl thiuram disulfide 1

Selenium dimethyl dithiocarbamate 1

Minutes
vulcanized

at 160 ^° C

32

Physical Properties

Tensile Strength, kg / cm ² - Elongation,%

Modulus at 200 to 400%, kg / cm ²

Heat treated
Comparative experiment _{with activator}

185.5
18.3-31.3

173.6
21.1-44.3

164.5
26.7-40.8

158.8
29.5-46.4

Although the sample treated warm with the activator had a somewhat lower tensile strength than the non-heat-treated counter sample, the treated products showed a very significant improvement in the modulus (e.g. 29.5 compared to 21.1 kg / cm ² ) as well good elastic properties.

Example 4

Similar to Example 3, a further series of tests was carried out, but the clay mineral filler was used instead now a very fine hydrated silica with an average particle size from about 0.01 to 0.02 µ. There were 49 parts of silica per 100 parts of the butyl rubber. The mixture composition, the hot kneading method and the vulcanization mixture was the same as in Example 3. The vulcanized samples were as follows Characteristics:

r Physical properties Heat treated Minutes \ Tensile Strength, kg / cm ² - Elongation,% with activator vulcanized \ Modulus at 200 to 400%, kg / cm ² 154.7 25.3-42.2 at 160 ^° C Comparative experiment 151.2 175.0 30.9-51.3 16 15.5-25.3 161.0 61 19.7-33.0

As in Example 3, these data show that the samples heat treated in accordance with the present invention had Activator additives had a surprisingly higher modulus, e.g. B. 30.8 versus 19.6.

In practicing the present invention, various modifications are made to the general method possible. With certain mineral fillers, e.g. B. Precipitated hydrated silica, which has a small Amount, e.g. B. about 5%, held in the form of hydroxyl groups bound water on the surface of the For example, it may be desirable to add a small amount, e.g. B. 0.5 to 5, preferably about 1 to 3%, of a polyhydric alcohol such as glycol, propylene glycol, glycerin, or various amines either to be added before or during the heat treatment of the butyl rubber-silica mixture. That The result is an increased heat treatment reaction. The properties are enhanced by adding glycerine of butyl silicic acid mixed in the usual way

Mixtures, d. H. not heat treated mixtures, not much improved.

Another embodiment, which is particularly advantageous when incorporating relatively large amounts of mineral fillers, consists in the addition of a small amount, e.g. B. from 0.5 to 10, preferably from about 1 to 3 ⁰ J ₀ , of a partially immiscible plasticizer to the butyl rubber mixtures mixed with mineral fillers, in order to avoid sticking to the kneading rollers. Dibutyl phthalate is preferred for this purpose. Slightly lower or higher alkyl esters can also be used for this purpose, e.g. B. the corresponding ethyl, propyl, amyl phthalates, or mixed esters such as monoethyl monoisooctyl phthalate and other plasticizers containing oxygen, nitrogen or other elements or radicals to make the plasticizer at least partially immiscible with butyl rubber. Such agents with boundary miscibility properties are particularly advantageous for mixtures of substances which contain more than 40 parts of silica pigment per 100 parts of butyl rubber; however, they can also be added if necessary with lower proportions of mineral fillers. These additives can be added to the butyl rubber and the silica either before or during the heat treatment, but preferably when the sulfur and accelerators are added just before vulcanization.

Example 5
Dibenzo-p-quinonedioxime

This example shows the influence of various additives Amounts, 0.2 to 1.0%, of the particular heat treatment activator, dibenzo-p-quinonedioxime. This Activator has proven to be very beneficial for many mixtures of butyl rubber and mineral fillers, since it has a good activating effect, but not as easily as other activators, e.g. B. Quinone dioxime alone or p-dinitrosobenzene, causes stinging.

The following mixture was assumed for this series of experiments:

Butyl rubber 100.0 "]

hydrated silica ... 40.0> basic mixture

Stearic acid 2.0 J

Zinc oxide 5.0

Sulfur 2.0

Tellurium diethyl dithio

carbamate
Mercaptobenzothiazole

Vulcanizing agent
1.0

1.0 y

40

45

The master batch was mixed on a mixer roll under normal conditions. She was in divided into five parts, one for the comparative experiment, while each of the four other parts has different levels Amounts of dibenzo-p-quinonedioxime as activator in the amounts given in the table below admitted. After adding the activator, the individual mixtures were on the same roller for 10 minutes Treated warm at 150 to 155 ° C, whereupon each mixture was allowed to cool, the vulcanizing agents in the the amounts shown above, then added them for 45 minutes in the form of conventional test plates vulcanized at 143 ° C and finally examined for their physical properties. The results are compiled in the following table III:

Table III

Module, kg / cm ² ,
for stretching

100%

200%

300%

400%

500 "/ ₀

600%

700%

Tensile strenght,

kg / cm ²

Strain, % .

Attempt. I 3 I.

Parts of dibenzo-p-quinone dioxime

0 0.2 0.4 0.7 4.9 6.3 7.0 73.8 9.8 10.5 17.6 24.6 14.1 18.3 32.3 49.0 21.1 30.9 52.7 78.0 38.7 54.5 86.8 121.0 84.3 106.9 142.3 169.4 152.5 166.5 188.0 182.8 186.4 193.3 197.5 790 765 710 675

117.1

163.5

174.0 520

These data show that the activator does not affect tensile strength or elongation much, but leads to very surprising improvements in modulus. In comparison to the module of 14 kg / cm ² for 300% elongation in the comparison sample (without the addition of activator), for. B. the addition of 0.2% activator an increase in the modulus to 18.2 kg / cm ² , and even larger amounts of activator, ie 0.4, 0.7 and 1.0 parts, led to ever higher modulus values, namely of 32.2, 49.0 and 80.5 kg / cm ² . This means that the substance mixtures heat-treated in the presence of an activator had very much better elastic properties than the counter sample.

In contrast to the corresponding heat treatment of butyl rubber with carbon black, the corresponding Heat treatment with hydrated silica as a filler in the presence of a heat treatment activator initially to an apparent scorch of the mixture; during the first few minutes on the warm kneader the mass becomes tough, brittle and dry. Knots may form and the fur may peel off loosen the kneading drum. However, if the concentration of the activator is not too high, this "burning state" lasts does not stay on for long, and if the hot kneading is continued, the mass becomes smooth again. First she will soft, so that it clings firmly to the kneading rollers, and finally the cracks and the superficial one disappear Roughness. The time required to achieve this smoothing will vary depending on the activator and its Concentration as well as depending on the strength of the heating and the kneading treatment. Although this heat treatment Occasionally difficult to perform in an open mixing drum, but it is quick and easy possible in a Banbury mixer.

If you warm the butyl rubber and the activator alone before adding the silica filler kneaded, little or no improvement can be achieved. This shows that the gain of the Butyl rubber with the silica filler - at least in part - the result of a chemical There is a bond between the filler and the butyl rubber.

To achieve the best modulus and elasticity properties, the amount of heat treatment activator to be added should be increased with the incorporation of larger amounts of mineral fillers. This is totally novel and in surprising contrast to the heat treatment of mixtures of butyl rubber and soot, where e.g. B. 0.2% activator for activation

suffice the heat treatment within a very wide concentration range of soot.

Example 6

A number of attempts have been made at 40, 50 and 70 parts of the hydrated silica with 100 parts of butyl rubber in each case heat treated with varying amounts of dibenzo-p-quinonedioxime and applied to each of the three different amounts Silica added at least four or five different concentrations of the activator, as well as in each

a comparison test, without activator

carried out. The base mixes were kneaded warm ^{at 150 to 155: C for 30 minutes.} The base mixture and the vulcanizing agents had the same composition as in Example 5, except for the varying amounts of silica, and 3 parts of dibutyl phthalate were added with the vulcanizing agents in order to prevent sticking to the kneading rollers.

For the sake of brevity, the results are summarized as follows:

The mixtures, which were heat-treated in the presence of the activator mixtures in amounts of 0.2 to 1.0% and which contained 40% silica, exhibited the addition of about 0.3 to 0.5% activator (in the most favorable concentration, which is determined graphically by interpolation was) a maximum modulus for 300% elongation of about 68.5 kg cm ² . Compared to the module of the comparison sample of only 15.5 kg / cm ² (heat-treated without activator), this represents a huge increase. resulted in an activator concentration of about 0.9 to 1.0 a maximum modulus for 300% elongation of about 72.0 kg, cm ² , while the modulus of the comparison sample was only 32.3 kg (without activator).

Similarly, the even higher amount of 70% silica when heat treated in the presence of about 0.7 to 2.4% activator resulted in an increase in modulus values from about 49.2 to a maximum of about 86.5 kg / cm ² , and a concentration of about 2.0 to 2.25% activator, compared to 28 kg / cm ² in the comparative experiment (without activator). To achieve the highest values of the module for 300% elongation, higher concentrations of silica also require larger activator additives during the heat treatment. The following table lists the physical and dynamic properties of the three substance mixtures, each with approximately the most favorable concentration of heat treatment activator for each of the three silica concentrations, as well as the corresponding comparative sample for each of them.

Table IV

Parts of hydrated silica to 100 parts of polymer I 50 I 70

Parts of dibenzo-p-quinonedioxime per 100 parts of polymer 0.4 I - 1.0 I - I

2.25

Modulus, kg / cm ² for elongation

100%

200%.

300%

400%

500%

600%

700%

Tensile strength, kg / cm ²

Strain, %

nf *) · 10 ~ ⁶ , Poisen times vibrations per second ..

Dynamic modulus K · 10 ~ ⁷ , dynes / cm

Relative damping,%

*) Internal viscosity.

The heat treatment of mixtures of butyl rubber and hydrated silica and Activators achieved surprising improvements in the elastic properties are shown very clearly when comparing the tension-elongation ratios of samples that were tested for elongation and relaxation became; especially if such a treatment was repeated several times.

The comparative samples which have not been heat-treated show at low elongations, e.g. B. up to 20 or 30%, one very undesirable stiffness, which can be seen from the unusually high load, and at relatively with little additional load, the tension rises rapidly up to about 150% elongation. With the associated Relaxation takes place undesirably slowly in the comparison sample which has not been heat-treated Contraction takes place, and after relaxation the sample still retains a 20% permanent change in shape at.

On the other hand, the mixture shows that in the presence of dibenzo-p-quinonedioxime according to the present

87.9 12.7 15.5 25.0 45.0 94.9 162.3

182.8

750 3.17 7.37 29.4

13.4 11.6 14.1 36.6 14.1 35.2 68.5 17.9 72.0 106.5 28.1 115.3 158.2 46.8 163.1 91.4 204.6 147.0 193.4 178.9 218.6 575 800 640 1.48 6.35 2.34 6.42 10.9 7.79 16.9 38.0 21.4

18.3 22.5 31.3 52.0 92.8 125.2

137.1 795

too stiff for examination

Invention was heat-treated, a softness, flexibility and elasticity in the low elongation range (10 to 50% elongation) and achieved the entire Maximum load of 500 g with an elongation of only about 100% (compared to 150% for the non-heat-treated Cross check). When relaxing, the heat-treated mixture draws faster than that Comparison sample together and almost completely returns to its original shape, with the permanent change in shape is no more than about 5% versus 20% for the non-heat treated comparative sample.

The heat treatment of butyl rubber-silica mixtures easiest to do in a Banbury mixer. As with warm kneading result from heat treatment without the addition of an activator

only minor changes; on the other hand, when activators are added, there is a rapid reaction.

Claims (1)

Claim: Process for the pretreatment of vulcanizable, filler-containing, synthetic rubber, which was prepared by polymerizing a predominant amount of olefin with a smaller amount of diolefin and whose molecular weight is at least 20,000 and whose iodine number is about 0.5 to 50, by heating to 120 to 230 ⁰ C to achieve improved vulcanizates, characterized in that the Mixtures, the fillers of which are inert, heated in the presence of an organic heat conversion activator composed of an aromatic compound of the general formula p_ON - Ar (R) ₄ -NR ' ₂
in which Ar has an aromatic nucleus and R and R ' Mean hydrogen, alkyl, aryl or other hydrocarbon radicals, or from a quinoid compound with at least one nitrogen- or oxygen-containing group on the ring, with under Conditions are used in which vulcanization of the elastomer mixture is avoided. Considered publications:
Austrian Patent No. 162 570;
British Patent No. 493,552;
Canadian Patent No. 463,237;
Rubber and Asbestos, 1951, p. 168. © 109'578 / 433 4.61