DE1133882B - Process for the production of vulcanizable rubber compounds with improved properties - Google Patents

Description

GERMAN

PATENT OFFICE

kl. 39 b 5/07

INTERNATIONAL KL.

COSc; d

D 25510 IVd / 39b

REGISTRATION DATE: 29 A PRIL 1957

NOTICE
THE REGISTRATION
ANDOUTPUTE
EDITORIAL: JULY 26, 1962

In the manufacture of rubber articles, for example tires, rubber with a reinforcing carbon black, with vulcanizing agents and other mixture components to form a vulcanizable Mixture mixed together and then vulcanized while molding.

According to the proposal of the present invention, there is the method of making vulcanizable ones Rubber mixtures in that carbon black and formaldehyde in the rubber with a condensation catalyst are mixed in, the dispersion obtained in this way for 2.5 to 40 minutes of heat treatment at a temperature between 100 and 200 ° C and incorporated after cooling in the mixture vulcanizing agent will. In practice, a temperature of around 140 ° C has proven to be very suitable.

The heat treatment is expediently done with simultaneous mechanical processing, however, the effect can also be achieved without kneading or rolling the dispersion. The after the present Mixtures obtained from the method can be vulcanized in a known manner with shaping will.

With regard to the volatility of the formaldehyde, it is advisable to use it in the form of a to add its polymers or in the form of a compound which splits off formaldehyde with the supply of heat. Such polymers and compounds include, for example, paraformaldehyde, Metaformaldehyde or hexamethylenetetramine. If hexamethylenetetramine is used, the Heating the rubber mixture releases ammonia, which acts as a condensation catalyst. In this In case it is not necessary to add a special condensation catalyst. On the other hand, however, it is not absolutely necessary to add an alkaline catalyst, since acidic catalysts, like aluminum chloride, also act with formaldehyde.

In another embodiment of the method, it is also possible to use rubber, carbon black, formaldehyde, With the exception of the catalyst, the other components of the mixture and the vulcanization accelerators of the sulfur, which is added before vulcanization, to the heat treatment.

The heat treatment is expediently carried out on the usual rubber processing machines, such as rolling mills or in kneaders. The duration of treatment is preferably between 10 and 25 minutes, depending on the type of manufacturing process used

of vulcanizable rubber compounds with improved properties

Applicant: Dunlop Rubber Company Limited, London

Representative: Dipl.-Ing. E. Rathmann, patent attorney, Frankfurt / M., Neue Mainzer Str. 40-42

Claimed priority: Great Britain dated April 28, 1956 (No. 13 085)

Roy Hickson, Basingstoke, Hampshire

(Great Britain), has been named as the inventor

working machine. So is z. B. the optimal treatment time in a kneader in which the mixture can be easily heated to 170 ° C for 10 minutes while working on one open rolling mill is usually larger. If necessary, the heat treatment can also be carried out when the bed is at rest Mixture, e.g. B. in a press or a heating cabinet.

The amount of formaldehyde is about 0.1 to 10 percent by weight based on rubber, however it has been found that amounts of about 1 to 2 percent by weight are particularly advantageous. The amount of the carbon black is the one commonly used to reinforce rubber, i. H. 5 to 150 parts by weight per 100 parts by weight rubber, preferably 5 to 75 parts by weight per 100 parts by weight of rubber. The required amount of condensation catalyst is usually between 0.1 and 0.5 percent by weight based on rubber.

The present method can be used with natural rubber as well as with synthetic rubber, especially in the case of a synthetic rubber which is a polymer of a conjugated diene, for example Polybutadiene is, or in the case of a copolymer of a conjugated diene and one with this copolymerizable compound, such as copolymers of isobutylene-butadiene, butadiene- Acrylonitrile, butadiene-styrene, or also with a polymer from a substituted, conjugate

209 627/347

gated diene with the group CH ₂ = C-Cl, such as polychloroprene. Vulcanizable regenerates can be used as well as oil-extended rubber.

Rubber compounds produced by the present process produce vulcanizates with increased hardness and elasticity, while the other physical properties remain unchanged remain or in some cases also be improved.

In the examples below, the vulcanization accelerator N-cyclohexyl-2-benzothiazylsulfenamide is used.

example 1

Two tire tread compounds were made according to the following recipe:

Natural rubber

Furnace soot with high abrasion resistance

Sewer black with medium processability

Zinc oxide

Stearic acid

mineral oil

Anti-aging, mainly made of phenyl - /? - naphthylamine
with additions of diphenylamine and diphenylp-phenylenediamine

Portions of each mixture were placed on a 153 ° C roller (mixture temperature) for 20 minutes.

100

1.27

100

_ M. 300 0 Z. F. B. D. 50 6.77 S. 6.77 2.54 BSH 2.54 3.72 E. 3.72 Bl. V.

1.27 to 145 to 148 ° C) with the addition of varying amounts Hexamethylenetetramine rolled.

The addition of hexamethylenetetramine in the case of mixture A was 2, 3.5 and 5 parts by weight and respectively for mixture B 3.5 parts by weight, based on rubber. Finally, with the addition of 2.78 parts by weight Sulfur and 0.51 parts by weight of accelerator vulcanized. For comparison were Parts of the two mixtures A and B are heat-treated without the addition of hexamethylenetetramine and then vulcanized. In addition, the mixtures were made without heat treatment and without additives vulcanized by hexamethylenetetramine. The optimal physical properties of the vulcanizates of Mixture A are shown in Table 1A and of Mixture B in Table IB. Abbreviations in these tables have the following meaning:

HMT = parts by weight of hexamethylenetetramine
on 100 parts by weight of rubber.
Module in kg / cm ² at 300%> elongation. Tensile strength in kg / cm ² .
Elongation at break in%.
Tear strength in kg / cm.
⁰ hardness (British standard).
Rebound resilience.

% permanent deformation.
30th

All mixture examples, with the exception of the first in each case in the tables, were subjected to a heat treatment before vulcanization. The vulcanization took place for 20 minutes in ^{molds heated with steam at a pressure of 2.8 kg / cm 2} with a rise time of 15 minutes.

Table IA

HMT M. 300 Z. F. B. D. S. BSH E. Bl. V. 0 128 198 440 135 63 63 29 0 123 158 380 110 57 67 36 2 176 250 420 134 69 76 28 3.5 175 242 415 150 67 76 28.5 5.0 180 246 420 138 70 75 27

Table IB

HMT M. 300 Z. F. B. D. S. BSH E. 0 71 207 600 145 59 61 0 62 130 490 56 50 63.3 3.5 99 251 575 145 61 69

Example 2

A synthetic rubber consisting of a copolymer of butadiene and styrene was made however, together with the mixture components specified below, sulfur and accelerators except, with the addition of 2, 3.5 or 5 parts by weight of hexamethylenetetramine, based on Parts by weight of rubber (samples D, E and F), rolled for minutes on a 150 ° C roller. For comparison, a control mixture containing only carbon black was subjected to the heat treatment (Pattern B). After the heat treatment and after the material had cooled down, all samples were

5 6

mixed according to the following recipe and then for 60 minutes at a steam pressure of

2.8 kg / cm ² vulcanized with a rise time of 15 minutes.

Parts by weight

Cold rubber 100.00

Sulfur 1.75

Accelerator 1.00

Stearic acid, 1.00

Zinc oxide 5.00

Mineral oil 7.00

Carbon black 50.00

Age protection as in Example 1 1.00

Hexamethylenetetramine as above

specified

An identical mixture was made with the addition of 15 tetramins to represent the vulcanization. the

2 parts by weight of hexamethylenetetramine, based on the physical properties of all of the above

Rubber, the usual vulcanizing agents and synthetic rubber mixtures are listed in Table 3

but vulcanized without heat treatment (sample reproduced. The abbreviations have the same

C). This experiment was carried out in order to reduce the sub-meaning as in Example 1. Sample A contained none

retired to a heat-treated mixture and zo hexamethylenetetramine and was made without prior

also vulcanized the influence of excess hexamethylene heat treatment.

Table 3

template HMT M. 300 Z. F. B. D. S. BSH E. Bl. V. A. 0 126 214 475 45 60 59 14.5 B. 0 152 204 395 39 59 63 14th C. 2 165 195 375 46 64 65 11 D. 2 178 221 285 45 62 69 13th E. 3.5 174 218 385 40 63 69 13th F. 5.0 174 204 365 45 63 70 12th

From the table it can be seen that a significant improvement in elasticity is achieved, without the other physical properties deteriorating significantly.

Example 3

A kneader was charged with natural rubber, carbon black and hexamethylenetetramine. The temperature the mixture rose to 190 ° C. and was held at this temperature for 10 minutes. The kneader was then emptied and the mixture was completely mixed after cooling on the roll (Pattern A).

For comparison, the same mixture was used under normal conditions and without the addition of hexamethylenetetramine manufactured (sample B).

Natural rubber

Furnace soot with high abrasion resistance

Hexamethylenetetramine

Age protection as in example 1

Zinc oxide

Stearic acid

accelerator

sulfur

mineral oil

Pattern A | Sample B parts by weight

100

65

0.5

2.5

100

The optimal physical properties of the mixtures vulcanized at a vapor pressure of 1.4 kg / cm ² can be seen in the following table:

mixture M. 300 Z. F. B. D. BSH E. S. Bl. V. A.
B. 176 183
192 225
340 74
74 74.6
64.1 103
124 22nd
29

Example 4

A natural rubber-carbon black mixture was produced on the roller, and paraformaldehyde and anti-aging agent were mixed in. This mixture was then placed in a kneader which was heated ^{with steam at a pressure of 4.2 kg / cm 2.} During kneading, finely powdered aluminum chloride was added, and the kneader punch

quickly lowered. The heat treatment lasted 20 minutes.

The mixture was then cooled and finish-mixed on the roll.

A mixture (B) was heat-treated in the same way, but without the addition of paraformaldehyde and aluminum chloride, while another comparative mixture (A) prepared in the usual manner became.

Natural rubber

Furnace soot with high abrasion resistance

Hexamethylenetetramine

Paraformaldehyde

Aluminum chloride, anhydrous

Zinc oxide

Stearic acid

accelerator

sulfur

Aging protection as in example 1.

100 50

10

0.5 2.5 2

100
50

10
2

0.5
2.5
2

100

50

10 2 0.5

2.5 2

100 50

0.25 10 2

0.5 2.5 2

Mixture C with hexamethylenetetramine was included in this series to enhance the effect of the to compare acidic and alkaline catalysis of formaldehyde condensation.

The optimal physical properties of the various mixtures are shown in the table below to see:

mixture M. 300 Z. F. B. D. S. BSH E. FSVO. A. 185 218 355 97 69 70 24 B. 211 227 340 88 65 75.5 22nd C. 220 224 320 85 70 78.5 25th D. - 214 275 71 68 78 19th

Natural rubber

Furnace soot with high abrasion resistance

Hexamethylenetetramine ...

Anti-aging protection

Zinc oxide

Stearic acid

accelerator

sulfur

mineral oil

100

From this it can be seen that the combination of part 3 was made with the addition of hexamethylene

Hardness and rebound resilience for mixtures C tetramin on a 152 ° C roller for 20 minutes

and B is better than the comparison mixtures A 35 long rolled.

and B. Mixtures 2 and 3 were then

For example, 5 recipes A or B are mixed.

A mixture of natural rubber, carbon black and anti-aging protection was made and three of the same Parts divided.

Part was mixed and vulcanized according to Recipe B as outlined below.

Part 2 was heat treated without mechanical kneading, namely

a) with and without hexamethylenetetramine in an oven for 48 hours at 70 ° C,

b) with and without hexamethylenetetramine in a press which was ^{heated with steam at 4.2 kg / cm 2} pressure, for 20 minutes.

100

50 50 1 - 2 2 5 5 2 2 0.5 0.5 2.5 2.5 5 5

The optimal physical properties of the various blends are as follows

See table:

mixture Heat treatment M. 300 Z. F. B. D. S. BSH E. FSVO. B. no 130 236 490 139 62 70.5 32 B, static j 48 hours at 70 ° C
20 minutes at 153 ° C 139
132 464
422 455
435 117
87 62
61 73.8
73.4 34.5
29 A, static -v 48 hours at 7O ⁰ C.
20 minutes at 153 ° C 171
172 517
530 ■ 455
475 134
121 66
66 75.5
75.5 31
29 A. 20 minutes at 153 ° C
rolled 156 483 440 135 63 78 33.5

It is evident that the mixtures heat-treated with the addition of hexamethylenetetramine are better compared to the others.

Claims (4)

Patent claims: 1. A method for producing a vulcanizable rubber mixture containing carbon black and formaldehyde, characterized in that carbon black and formaldehyde are mixed into the rubber with a condensation catalyst, the dispersion thus obtained 2.5 to 40 minutes of heat treatment at a temperature between 100 and 200 ° C is subjected and, after cooling, vulcanizing agents are incorporated into the mixture. 2. The method according to claim 1, characterized in that the formaldehyde is in the form a polymerisation product or in the form of a compound that releases formaldehyde when heated releases, is added. 3. The method according to claim 2, characterized in that a compound is added that releases a condensation catalyst. 4. The method according to any one of claims 1 to 3, characterized in that the heat treatment with simultaneous mechanical processing the dispersion takes place. Considered publications: Dawson and Porritt, Rubber Physical and Chemical Properties, 1935, p. 228, panel 614 (111).