DE1204404B - Process for the production of homogeneous rubber-silica mixtures - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

PEUTSCHES

PATENT OFFICE

EDITORIAL

Int. α .:

C08d

German class: 39 b -4/01

Number:
File number:
Registration date:
Display day:

1204404
C22325IVd / 39b
September 12, 1960
November 4, 1965

The subject of patent 1148 067 is a process for the production of homogeneous rubber-silica mixtures by co-precipitation of synthetic rubber dispersions and alkali silicate solutions in the presence of neutral electrolytes with acids and subsequent filtering, washing and drying, which is characterized in that a creamable rubber dispersion which contains an emulsifier resistant only in the alkaline range, mixed with the desired amount of alkali silicate solution and such an amount of aqueous neutral electrolyte solution that the electrolyte concentration is between 30 and 80 g / l, preferably between 40 and 60 g / l, in the cream obtained, then this Cream at temperatures between 15 and 30 ⁰ C with intensive stirring within 10 to 180 minutes evenly mixed with acid up to a pH value between 9 and 7, the electrolyte concentration having to be at the upper limit of the above range for shorter acid addition times, then the reaction mixture is optionally ^{heated to 80 to 100 °} C. for 10 to 120 minutes and, if appropriate, adjusted to a pH of 3 to 2 by further addition of acid.

It has been found that this method can advantageously be developed further if the The mixture is precipitated at temperatures between 0 and 15 ° C.

This makes it possible to largely reduce the amount of neutral electrolyte.

For example, the precipitation temperature, the electrolyte concentration may be in a decrease from 20 to 1O ⁰ C for 10 minutes precipitation time from 50 to 40 g / l reduce, or at constant electrolyte concentration of 40 g / l, the precipitation time of 60 to 10 minutes reduced will.

In the following examples, the relationship between the temperature of the fall and the concentration of the electrolyte is intended be set out.

example 1

666 g of a 22.5% strength ^e n butadiene-styrene rubber latex having a butadiene-styrene ratio of 76:24, which, based on the solids content, 8% of a mixture of 50 parts of the potassium salt of disproportionated resin acids and 50 parts of contains potassium stearate, 508 g of sodium water glass containing 75 g of silica, and 192.5 g of 20% strength sodium chloride solution ^e are separately cooled to 1O ⁰ C. In a 5-1 beaker are made with a method of making more homogeneous while stirring
Rubber-silica mixtures

Addition to the patent: 1148 067

Applicant:

Chemical works Hüls Aktiengesellschaft, Mari

Named as inventor:

Dr. Günter Maaß, Mari;

Dr. Paul Bernemann, Haltern (Westphalia)

Anchor stirrer of 9 cm diameter (350 rpm) latex and water glass mixed and then inside of one minute with the saline solution. The concentrations in this cream are: 30 g sodium chloride / l, 58.4 g silica / l and 116.8 g rubber / l.

Under external cooling the temperature is maintained during the subsequent precipitation at 10 ⁰ C. Within 60 minutes 350 ml of 1.5 N sulfuric acid, which has also been cooled to 1O ⁰ C, injected via a Schlickdüse, then the suspension is heated up and held for 15 minutes at 90 ⁰ C. The suspension is then adjusted to pH 3 with 165 ml of 1.5 η-sulfuric acid. It is stirred for a further 10 minutes, filtered, washed and dried. The mixture consists of a powdery powder with a silica content of 31.8%.

Example 2

666 g of the latex used in Example 1 are mixed as ^e in Example 1 with 366 g of sodium water glass containing 75 g of silica, and 256 g of 20% strength sodium chloride solution r at 5 ° C. The concentrations in the cream obtained are: 40 g sodium chloride / l, 58.4 g silica / l and 116.8 g rubber / l. With 350 ml of 1.5 η sulfuric acid at 5 to 8 ⁰ C in 10 minutes to the pH value 8, the suspension is ^{heated to 90 0} C and kept at this temperature for 10 minutes, then with 180 ml of 1.5 N -Sulfuric acid adjusted to pH 3, another 10 minutes

509 720/447

stirred, filtered, washed and dried. The silica content of the mixture is 32.55%.

Example 3

In a 300-1 container equipped with a high-speed propeller stirrer and baffle plates, 64.7 kg of a synthetic rubber latex of the composition as in Example 1 with 20.4% solids content and 28.9 kg of soda waterglass, containing 6.6 kg silica mixed and ig ^he added sodium chloride solution within 2 minutes 24.75 kg 20%. All solutions have been pre-cooled to 4 ° C. The concentrations in the cream are: 45 g sodium chloride / l, 60 g silica / l and 120 g rubber / l. While stirring vigorously, the pH is adjusted to 8 within 10 minutes with 3111.5 n-sulfuric acid, which has also been pre-cooled to 4 ° C. The temperature rises to 11 ° C during this time. The suspension is then heated to 90 ° C. and kept at this temperature for 30 minutes. The pH is adjusted to 3 with 111 1.5 η-sulfuric acid and the mixture is stirred for a further 15 minutes. The suspension is filtered through a rotary filter, then slurried twice in warm water and filtered. The product is dried in a circulating air cabinet at 80 ° C. for 10 hours. The silica content of the mixture is 31.8% »the water content 2% ·

Mixtures A and B are produced on a laboratory rolling mill according to the following recipes:

Silica-rubber mixture

according to example 3

Butadiene-styrene cold rubber

Highly active silica

Stearic acid

Zinc oxide

Amine mixture

Ethylene glycol

N-Cyclohexyl-2-benzthiazylsulfenamide
sulfur

150

2.5

2.5

2.0

3.0

Test flaps are vulcanized at 150 ° C from the deposited ready-mixed mixtures, from which ring-shaped ones are vulcanized Test specimen are punched. The test gives the following values:

Vulcanization time
(Minutes)

strength
(kg / cm ² )

Stretching (7o)

Module (kg / cm ^a ) 100 ° / "I 200% hardness (Shore A)

22 ° C

75 ° C

Elasticity (%)

22 ° C

75 ° C

Permanent
strain

CVo)

15th 116 205 30th 146 260 60 137 240 120 146 280 15th 159 565 30th 148 500 60 124 490 120 134 520

45 114 75 74 43 62 47 118 75 74 43 62 47 118 75 74 43 62 43 112 75 75 43 62

25th 37 65 65 36 53 24 40 70 67 36 52 25th 41 70 68 35 52 25th 39 70 67 34 52

For the production of these homogeneous rubber-silica mixtures other synthetic rubber dispersions can be used with equal success.

Claims (1)

Claim: Further development of the process for the production of homogeneous rubber-silica mixtures by adding a framable synthetic rubber dispersion that is only alkaline Contains area resistant emulsifier, with alkali silicate solutions and such an amount aqueous neutral electrolyte solution that the electrolyte concentration between 30 and 80 g / l in the cream obtained, this cream is precipitated with vigorous stirring within 10 to 180 minutes with acid at a pH between 9 and 7, optionally heating the Reaction mixture 10 to 120 minutes at 80 to 100 ° C and optionally adjusting to one pH value of 3 to 2 by adding further acid, according to patent 1148 067, characterized in that that the precipitation is carried out at temperatures between 0 and 15 ° C. 720/447 10.65 © Bundesdruckerei Berlin