DE1105605B - Process for the production of improved vulcanizates of butyl rubber mixtures - Google Patents

Description

The present invention relates to processes for the production of mixtures which can be vulcanized together, those made from butyl rubber and natural rubber, rubber-like copolymers of butadiene and Styrene and / or rubber-like copolymers of butadiene and acrylonitrile, sulfur and / or vulcanizing agents containing sulfur, in the presence of inorganic or organic lead compounds, containing oxygen, especially lead oxides and accelerators, especially ultra-accelerators.

Using a process like the one described above, novel and improved mix-vulcanisables can be produced Produce rubber mixtures by using unvulcanized butyl rubber, regenerated butyl rubber and / or partially vulcanized butyl rubber with the above lead compounds, a highly unsaturated natural rubber, GR-S rubber and / or Buna-N rubber, which is used for vulcanization required amounts of sulfur and / or sulfur-containing vulcanizing agents and preferably in conventional amounts (i.e. about 0 to 30 parts, preferably about 5 to 10 parts by weight per 100 parts by weight of all rubber hydrocarbons) of basic metal compounds, ζ. Β. Oxides of bivalent Metals such as zinc oxide, furthermore with about 0 to 5 parts by weight of vulcanization ultra-accelerators such as thiuram derivatives, alkyl thiocarbamates, e.g. B. diethyl dithiocarbamate, zinc dithiocarbamate, etc., mixed.

Until now it was considered impossible to make a mixture of butyl rubber and more unsaturated rubbers, especially when the amount of the highly unsaturated rubber is greater than about 4 percent by weight is to produce useful vulcanizates. Such mixtures were obtained during vulcanization only products that were heavily blistered and highly porous. In general, the vulcanized products are made from these Mixtures also not homogeneous, but layered; their tensile strength is low and they tend to to crack and peel off.

The inability of ordinary butyl rubber to deal with any amount of highly unsaturated rubbers to let vulcanize together such as natural rubber or synthetic rubber, the z. B. in the output It was described in 1954 by "Synthetic Rubber" by G. S. Whitby, has hindered its more extensive application so far of butyl rubber for the manufacture of rubber-like articles.

It is shown in the following that lead compounds and in particular lead oxides cause the vulcanization of Delay butyl rubber. It has heretofore been generally believed that the large difference between the vulcanization rates of butyl rubber compared to other synthetic rubbers or natural processes for the production

improved vulcanizates

of butyl rubber compounds

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

Rubber was the main reason for the formation of inferior vulcanizates of blends of butyl rubber with these other rubbers, and it was further believed that the presence of substances which retarded the vulcanization of butyl rubber, namely lead oxides, made the difference between the vulcanization rates of butyl rubber and strong unsaturated rubbers would increase. It is therefore extremely surprising that the addition of oxygen-containing lead compounds gives butyl rubber which can be perfectly vulcanized with highly unsaturated rubbers, the vulcanization rate of the rubber mixtures according to the invention being higher than that of each individual rubber component.
The lead compounds used are lead oxides, organic lead compounds and inorganic lead salts, which contain oxygen especially in their anionic portion, e.g. B. tribasic monohydric lead sulfates, basic lead silicate sulfates and dibasic lead phosphites. Particularly suitable compounds of this type

4-5 are e.g. B. PbO, Pb ₃ O ₄ , Pb ₂ O ₂ , lead salicylate, tribasic monohydrobead maleate, dibasic lead stearate, dibasic lead phthalate, normal lead stearate.

The lead compounds are particularly effective in connection with the so-called "ultra-accelerators",

z. B. tetramethylthiuram disulfide or tellurium diethyldithiocarbamate.

The butyl rubber used generally consists of a copolymer of a major part of an olefin, for example from a relatively

109 57S / 434

low molecular weight isoolefin (ζ. Β. isobutylene) and a smaller proportion of a multiolefin, the ratio of the isoolefin to the multiolefin being preferred is about 90 to 99.5% to about 10 to 0.5%.

After vulcanization, the copolymers show good elasticity, tensile strength, and abrasion resistance Resistance to bending. The butyl copolymers can also be mixed with various fillers, pigments, Mix plasticizers and antioxidants.

The amount of butyl rubber used with the highly unsaturated rubber (s) can vary considerably, e.g. B. between 99 percent by weight butyl rubber to 1 percent by weight of the unsaturated rubber up to 1 percent by weight of butyl rubber to 99 percent by weight of the unsaturated rubber. The amounts of each of these ingredients depend largely on the end use for which the product is intended. The butyl rubber can also contain any amount of regenerated or partially vulcanized butyl rubber alone or together with the butyl rubber.

It advantageously be about 3 to 30 weight percent, preferably 3 to 4 up to 20 weight percent, lead compound, based on the known total amount of the rubber, and applied 0.1 to 2 ° / ₀ ultra-accelerator. The vulcanization can and times include temperatures between about 120 and 200 ⁰ C, preferably about 140 and 16O ⁰ C, between about one minute and several hours or more; usually vulcanization takes about 10 minutes to 2 hours.

Example I.

A basic mixture of butyl and butadiene-styrene rubber was used, usual fillers and vulcanizing agents in the following composition:

composition

Butyl rubber (GR-I-17).

Butadiene-styrene rubber

Semi-reinforcing carbon black.

Zinc oxide

Stearic acid

Tetramethylthiuram disulfide

sulfur

Parts by weight

75

25th

50 5.0 0.5 1.0 3.0

Eighteen divided portions of this mixture were each given for 40 minutes at 153 ° C in the presence of 5 parts by weight various mixed vulcanizing agents, some of which contained lead monoxide. the The results of these tests can be seen from the following table.

Vulcanizing agents

sample Effective additives PbO MnO ₂ tensile strenght
kg / cm ² More available
PbO content Pb ₃ O ₄ Barium ricinoleate 1 Pb ₂ O ₃ Regular calcium stearate 81.9 100 2 PbO ₂ HgO 87.6 100 3 Regular lead salicylate BaO 85.4 100 4th Tribasic monohydric lead sulfate 92.0 100 5 Basic lead silicate sulfate 68.0 100 6th White lead 91.0 67 7th Tribasic monohydrobead maleate 75.6 45 8th Dibasic lead phthalate 83.0 - 9 Regular lead stearate 85.0 66 10 Dibasic lead phosphite 85.0 82 11 Dibasic lead stearate 78.1 12th Ineffective additives 91.7 13th 89.2 14th 42.7 0 15th 30.1 0 16 22.1 0 17th 47.6 0 18th 37.5 0

It can be seen from this table that those mixtures which contain oxygen-containing lead compounds give products with sufficient tensile strengths, ie from about 70 to 91 kg / cm ² . Incidentally, the rubber products of Samples 1 to 13 inclusive were dense and homogeneous, while the other samples were porous and not homogeneous.

Example II

The following three basic mixes (A, B, C) were prepared in a laboratory kneader:

Natural rubber 100

Zinc oxide 5

Sulfur 3

Stearic acid 1

2-mercaptobenzothiazole 1

Butyl rubber 100

Sewer soot 50

Stearic acid 0.5

Zinc oxide 5

Tetramethylthiuram disulfide 1.25

Sulfur 2

Reclaimed butyl rubber 166

Zinc oxide 3

Tetramethylthiuram disulfide 1.25

PbO ₂ 10

These base mixes were then used in the following Parts by weight mixed together and then vulcanized at 153 ° C for 30 minutes.

1 ti together
3 ensetzu
4th ng 9
90 6th mixture 3
90 Z
2 3
45
45 9
90 9
45
45 5 A 3
90 B. C.

The following physical properties were found :

Tensile strain properties

Tensile modulus, kg / cm ² , at

100 ° / ₀ stretch

200 ° / ₀ stretch

300 ° / _o strength at break

400% elongation

500 ° / ₀ stretch

600 ° / ₀ elongation

Tensile strength, kg / cm ²

Strain, %

1 2 3 4th 5 8.4 17.9 13.3 9.8 14.7 14.7 28.1 26.0 17.5 20.3 26.6 42.0 44.1 29.7 24.5 42.0 57.4 67.2 45.9 27.7 58.8 74.9 93.8 52.5 94.5 119.1 71.1 105.0 129.2 72.1 30.5 575 645 635 540 480

14.0 24.5 37.5 54.0 73.6

90.7 585

From this it can be stated that the substance mixtures 1, 3, 4 and 6, which _{contain PbO 2} , have good physical properties, such as tensile strength, tensile strength modulus and elongation. Mixtures 2 and 5 did not contain any PbO ₂ . The mixture 2 contained little natural rubber (4.5 ° / _0), based on the total content of rubber hydrocarbons. In spite of this, the vulcanized ball showed a peculiar, porous, cracked and non-homogeneous appearance that occurs with "contaminated" butyl rubber.

Mixture 5, with 13.5% natural rubber content, based on the total content of rubber-hydrocarbons, was very blistered. Their very poor properties made them vulcanized rubber worthless.

Example III

The following three basic mixes were prepared according to the procedure described in Example II:

Natural rubber 100

Zinc oxide 5

Sulfur 3

Stearic acid 1

2-mercaptobenzothiazole 1

Butyl rubber 100

Stearic acid 0.5

Zinc oxide 5.0

Tetramethylthiuram disulfide 2

Sulfur 2

Sewer soot 50

Reclaimed butyl rubber 166

Zinc oxide 3

Tetramethylthiuram disulfide 1.25

Sulfur 1

These masterbatches were in the following amounts

mixed together and vulcanized as in Example II for 30 minutes.

mixture 1 2 Z together
3 änsetzu
4th ng ₅ 6th 50 A 9 9 9 9 9 9 D. 90 Qn 90 90 45
4S 45
45 C. 5 - 5 5 PbO ₂

Blends 1 and 2 were made from regenerated butyl rubber and contained 14.2 percent by weight Natural rubber, based on the total rubber hydrocarbon. Mixes 3 and 4 were made from butyl rubber and contained 12.6 percent by weight of natural rubber, based on the Total content of rubber hydrocarbons. Mixtures 5 and 6 were made from a mixture of Butyl rubber and regenerated butyl rubber and contained 13 percent by weight natural rubber, based on the total rubber content.

The following physical properties were determined:

Tensile load properties

Tensile modulus, kg / cm ² , at

lOO'Y yer stretch

200 ° / ₀ stretch

300 ° / _o strength at break

400 ° / ₀ iger elongation

500 ° / ₀ stretch

600 ° / ₀ elongation

Tensile strength, kg / cm ²

Elongation, ° / ₀

1 2 3 4th 5 9.8 11.9 20.3 19.6 15.4 15.4 24.1 26.6 35.1 23.1 25.9 39.9 33.6 53.2 31.4 37.1 56.7 42.0 72.2 38.5 49.1 99.8 122.5 38.5 72.5 50.4 131.0 38.5 410 495 560 635 435

20.0 37.1 57.4 78.4

100.8 485

After removal from the mold, Mixtures 1, 3 and 5, which did not _{contain PbO 2} , were porous and vesicular. The poor physical properties show that their vulcanization state is unsatisfactory. On the other hand, Mixtures 2, 4 and 6 containing PbO _{2 had} the desired appearance and physical properties and were extremely valuable vulcanizates.

This shows that mixtures of conventional mixtures of butyl rubber and natural rubber cannot be vulcanized together satisfactorily, but that the addition of PbO ₂ to these mixtures enables good vulcanizates to be produced.

Example IV

75 parts by weight of butyl rubber and 25 parts by weight of butadiene-acrylonitrile rubber were with the various compounds listed below and in the case of experiment 1 for 40 minutes at 153 ° C in the absence of lead compounds, and in the case of Experiment 2 under the same conditions vulcanized in the presence of 5 parts by weight of lead dioxide. The tensile strength modules given below were obtained and tensile strengths found:

attempt

1 2 (Blind attempt) 75 75 25th 25th 50 50 0.5 0.5 5 5 1 1 3 3 - 5 35.8 77.3 42 85.7

Butyl rubber

Butadiene-acrylonitrile rubber

Semi-reinforcing carbon black

Stearic acid

Zinc oxide

Tetramethylthiuram disulfide

sulfur

PbO ₂

Tensile modulus at 100 ° / ₀ iger

Elongation, kg / cm ²

Tensile strength, kg / cm ²

These data show that the mixture of butyl rubber vulcanized together with lead dioxide and butadiene-acrylonitrile rubber have twice the modulus and twice the tensile strength as the cross sample exhibited. In addition, the lead dioxide-containing mixture was not porous, but smooth, dense and hardly showed any cracks or blisters, while the same mixture, produced but without lead dioxide, gave vulcanizates that were very much were inhomogeneous, very rich in bubbles, cracked and porous and represented unusable vulcanizates.

Example V

The following example illustrates that high sulfur content alone or in conjunction with the addition of Lead compounds, ζ. B. lead dioxide, useful semi-hard vulcanizates are, especially with mixtures of Butyl rubber with butadiene-styrene rubber. It was z. B. found that hard but flexible Mixtures of butyl rubber and other highly unsaturated types of rubber can be produced in this way, that the sulfur content is increased to about 10 to 40, in particular about 15 to 25 parts by weight to 100 parts by weight of the total rubber hydrocarbons. When treated with or without lead dioxide or other lead compounds for at least 10 minutes these mixtures can be vulcanized in a satisfactory manner. Even when using 15 to 25 parts of sulfur without lead in the mixtures, the vulcanizates are free of cracks and bubbles and have a desired Shore hardness of about 50 to 100. However, by adding lead compounds the mixtures can be improved even further, as will be shown below.

The following mixtures were prepared and vulcanized in a conventional rubber kneader measuring 15 × 30 cm them for 40 minutes at 153 ° C.

composition

Butyl rubber

Butadiene-styrene rubber

Stearic acid

Semi-reinforcing carbon black.

Zinc oxide

Tetramethylthiuram disulfide

sulfur

PbO ₂

Appearance

75
25th

0.5
50

very
dull,
cracked,
blistered,
peeling off,
non-homogeneous

75

25th

50

smooth

glittering,

hard, 75
25th

0.5
50

1
15th

dull,
hard,

0.5

15th
5

smooth

glittering,

hard,

75
25th

0.5
50

1
25th

dull,
hard,

75
25th

0.5
50
5
1

25th
5

smooth
glittering,
very hard,

without cracks, bubbles and practically completely homogeneous

The Shore hardness was determined with a Shore hardness meter.

The vulcanized compounds B, D and F are flawless in every respect, non-porous, flexible and without bumps. Vulcanized Blends C and E showed slight surface damage, but were completely free of cracks, bubbles and layer-like peeling or other signs of incompatibilities during vulcanization. Mixture A, as indicated above, but in the absence of lead oxide was vulcanized, could not be vulcanized together, while this was quite possible with mixture B and a gave a soft and rubbery product.

The Shore hardness of mixtures C to F was around 75 to 80, so it was superior to that of mixtures A and B, which was only between around 30 and 40. Incidentally, mixtures D and F, which contained PbO ₂ and 15 and 25 parts by weight of sulfur, were not only smooth, shiny, homogeneous mixed vulcanizates, but they were also sufficiently flexible that a 0.1905 cm thick sheet could be turned over from them without cracking Let bend 180 °.

The mixed butyl rubber vulcanizates according to the present invention are particularly advantageous for production Can be used on pneumatic tires with or without inner tube.

Claims (4)

PATENT CLAIMS: 1. A process for the production of improved VuI-kanisate of mixtures of a rubber-like copolymer, which contains a larger proportion of C ₄ - to C ₈ -01efinen and a smaller proportion of a C ₄ - to C ₁₄ -Multiolefin, with a more unsaturated rubber, which contain sufficient amounts of sulfur for vulcanization, characterized in that the mixture of rubbers is vulcanized in the presence of an oxygen-containing lead compound and an ultra-accelerator in the customary manner. 2. The method according to claim 1, characterized in that the rubber-like copolymers from consists of a major proportion of an isoolefin and a minor proportion of a conjugated olefin and that, as the oxygen-containing lead compound, oxides of lead, lead salts of organic acids, inorganic ones Lead salts of oxygen-containing acids or mixtures thereof are added. 3. The method according to claim 1 and 2, characterized in that the copolymer is a butyl rubber of 85 to 99.5 percent by weight of a C ₄ - to C ₇ isoolefin and about 15 to 0.5 percent by weight of a C ₄ - to C ₁₀ multiolefin and that natural rubber, GR-S rubber, Buna-N rubber or mixtures thereof are added to this as the more unsaturated rubber. 4. The method according to claim 1 to 3, characterized in that in the mixtures sulfur in an amount of about 2 to 50 and preferably 10 to 40 parts by weight is used that the Lead compound is used in a concentration of about 3 to 30 parts by weight and that of any zinc oxide still present is about 5 to 30 parts by weight. Considered publications:
U.S. Patent No. 2,391,742;
Rubber World, 129, pp. 348 to 353 (1953);
Kluckow, Die Praxis des Gummichemikers, 1954, p. 168, 3rd paragraph. © 109 578/434 4.61