DE1794380C3 - Use of chrysotile asbestos as a thixotropic thickener. Eliminated from: 1619771 - Google Patents

Description

The use of asbestos as a thickener in the manufacture of lubricating greases from lubricating oils is already known per se, for example from US Pat. No. 3,010,896 and from an article by C. J. B ο η e r, “Manufacture and Application of Lubricating Greases ".

It has now been found that a vastly improved thickening agent for liquids, for example for the production of thixotropic lubricating greases or thixotropic paints or similar Compositions obtained by subjecting chrysotile asbestos to a jet mill subject. After treatment in the jet mill, the asbestos is in the form of fine fibers, «Whose diameter lies in the colloidal range.

The chrysotile asbestos fibers can be produced by being under positive pressure and at a temperature a moving body in a gaseous medium between room temperature and 650 ° C produces suspended asbestos particles and in these continuously further gaseous medium in several Flowing at a temperature in said range and at a high speed with generation introduces strong turbulence in the body and thus with comminution of the suspended particles that Crushed asbestos particles together with the gaseous medium continuously withdraws and the fine Separating asbestos particles from the suspending gas. Air and steam are used as the suspending medium preferred.

Jet mills of a known type are suitable for comminuting the asbestos particles. One is preferred Jet mill, in which relatively large particles are suspended in a gas medium and around a internally arranged base are swirled and further gas is generated in the vertebral body by turbulence in the body and with crushing and attrition of the particles.

When using air as the gaseous grinding medium, the jet mill is expediently operated at a pressure of about 7 to 35 and preferably 7 to 21 kg / cm ² (above atmospheric pressure). The additional air generating turbulence can be introduced into the vertebral body containing the asbestos particles at a pressure of about 7 to 35 kg / cm ^{2, preferably about 10.5 to 17.5 kg / cm 2.} Air at room temperature is preferably used. The average particle size can be varied by regulating the air speed and temperature as well as the feed rate for the asbestos. The product can be separated from the suspending medium in any manner; before-

example 1

Production of
jet-milled chrysotile asbestos

Chrysotile asbestos particles were introduced into a commercially available jet mill with a grinding chamber diameter of 20.3 cm through a venturi injector (with compressed air from 10.5 to 17.5 kg / cm ² ) at a rate of about 25 g / min. ^{Air at room temperature with a pressure of about 21 kg / cm 2 was} blown into the vortex body of asbes; particles formed in the jet mill to generate a turbulent mass. The finely divided asbestos fibers were separated from the air flow in a bag catcher.

Details of the type and amount of the starting materials are given in Tables 1 and 2 below specified.

The particle size of the feedstock is only limited in that the material can get into the venturi injector must have imported. Asbestos particles that are too large can reduce the fiber length on the required area to be subjected to a pretreatment.

Example 2
Thickening of polyesters

As the resin, a liquid polyester resin having a viscosity of 150 was to 20OcP at 25 ⁰ C (measured in a Brookfield viscometer using a spindle no. 2 / min at 20 rpm) was used and one set at 41% styrene content. The chrysotile asbestos fibers produced according to Example 1 were used as thickening agent. The polyester was mixed with the thickener and the increase in viscosity at 6 rpm and 60 rpm was measured in a Brookfield viscometer. The viscosity of the thickened resin was determined immediately and after storage at 38 ° C. for 7 days. The settling power of the thickened polyester resins was determined by measuring the supernatant liquid.

Example 3
Thickening of polyepoxides

The resin used was a liquid polyepoxide with a viscosity of 400 to 60OcP at 25 ° C and with an epoxy equivalent of 175 to 200 is used. The thickening effect of the prepared according to Example 1 finely divided chrysotile asbestos fibers were determined as in Example 2. The results can be found in the following table 2.

794

Table 1

No. Kind of used
Chrysotile asbestos Parts thickener each
100 parts
polyester immediately gf
6 rpm viscosity in el
: rnessen
60 rpm »
after
7 days
6 rpm AbseGvermogeo,%
supernatant liquid
after 7 days 1 Chrysotile asbestos *) 0.25 1800 800 2000 10.0 2 Arizona filter
quality FM-3 0.3 160C 690 1800 9.5 3 Quebec Lake-
Asbestos 7D5 0.45 2500 940 2800 5.3 4th Chrysotile asbestos *) 0.3 2600 950 2800 3.8 5 Californian
Coalinga 1.5 3000 1880 3600 3.5 6th South African
blue crocidolite 1.2 1800 820 1600 4.0

·) Partly defibrated by acid treatment.

Table 2

Kind of used
Chrysotile asbestos

Californian
Coalinga

Parts of thickener per 100 parts of polyepoxide

2.0

Viscosity in cP measured immediately rpm I 60 rpm

200

3400

after 7 days
at 54 ° C
6 rpm

12 600

Deductibility,%

protruding

liquid

after 7 days

4.2

Claims (1)

Claim: Use of chrysotile asbestos fibers. With a diameter i: n colloidal area formed by grinding chrysotile asbestos into a Jet mill can be obtained as a thixotropic thickener. bag catchers or filters are preferably used for this purpose, but cyclone separators or can also be used other separators are used. Compared to the previously used as a thickener pickled asbestos shows the jet-milled chrysotube asbestos in the form of fibers with a diameter in the colloidal range in particular significantly improved thixotropic properties. A measure of this is that Thixotropy index; d. H. the ratio of the viscosities at 6 and at 60 rpm. To explain the invention in more detail, the The following examples are used.