DE1669900C - Thickener - Google Patents

Description

The invention relates to the use of a homogeneous mixture of (A) pure fibers, morphologically uniform polyoxymelhylene obtained by the catalytic polymerization of trioxane and (B) 5 to 50 percent by weight of highly dispersed pyrogenic or precipitated oxides, Mixed oxides or oxide mixtures of aluminum and / or titanium and / or silicon as thickeners for polyester resins or lacquers. Epoxies or hydrocarbons.

Fibrous polyoxymethylene is known by radiation-chemical polymerization of crystallized trioxane by adding the latter exposed to ionizing radiation and then at temperatures below the melting point is polymerized for a long time. Fibrous polyoxymethylene is obtained by other known processes in another way, e.g. B. by cationic polymerization of trioxane, which in weak Solvents is suspended at temperatures below its melting point, or by polymerization of solid trioxane in contact with a cationic catalyst, causing a polymerization only takes place on the surface of the trioxane particle, while the underlying layers remain unchanged Trioxane persist, produced. In the latter process, however, not only pure fiber-shaped Products obtained, but also mixtures of fibrous polyoxymethylenes with either finely crystalline, powdery polymers or unaltered trioxane.

The pure fiber. by radiation polymerisii I ion obtained polyoxymethylene products are preferably found in connection with inorganic finely divided Oxides used as thickeners. The thickening effect of e.g. B. highly dispersed Silicic acid is known to be improved by blending it with fibrous polyoxymethylene will. At the same time, this reduces the formation of dust in the silica and its incorporation in systems to be thickened much easier.

In the case of a mixture of polyoxymethylene fibers with crystalline and powdery fractions obtained by cationic polymerization using the methods customary up to now, the thickening effect is significantly less than that of pure-fiber polyoxymethylene, even in the presence of highly dispersed inorganic oxides. since the thickening values fluctuate considerably due to the irregularity in the composition of the polyoxymethylene content, so that these products cannot be used as thickeners due to the impossibility of reproducibility of the thickening values. But even the mixtures consisting of pure fiber-form polyoxyethylene and inorganic oxides do not always meet the diverse requirements placed on thickeners.

The pure fiber-shaped polyolymethylene products of the mixture used according to the invention can be obtained not only by radiation-chemical polymerization but, surprisingly, also by polymerization of solid trioxane using a Kniloni catalyst, which avoids the discontinuous method of production via radiation polymerization, which is very expensive in terms of apparatus Morphologically uniform polyoxymethylene can be obtained, for example, by homogeneously distributing a cationic catalyst in a trioxane melt, then quenching the melt to a temperature below the trioxane melting point before starting the polymerization, polymerizing the completely solidified catalyst-containing melt and removing residual monomer residues.
As suitable finely divided oxides of metals and

ίο Metalloids have become aluminum oxide, titanium dioxide and silicon dioxide. These oxides can both be pyrogenic in the arc process or be produced by flame hydrolysis as well as by precipitation on the wet route. Mixtures too these oxides with each other are related to the invention Purposes. Furthermore, in special cases in their surface in the sense of a Organophilicity or hydrophobicity modified oxides or several different oxides simultaneously in Form of a mechanical mixture or as so-called "mixed oxides" and;> oxide mixtures "(co-coagulates)" Find application. Under "mixed oxides" of metals and metalloids are in the sense the invention to dispose of such finely divided oxides

i5. stand, soft from one or more metal oxides and silicon dioxide, the primary particles of which already contain each oxide component. In contrast finely divided "oxide mixtures" also consist of one or more metal oxides and Silicon dioxide, but its to secondary particles co-coagulated primary particles of one each composed of metal oxides and silicon dioxide. The manufacture of such products can according to the method according to the Canadian patent 573 556 for the "mixed oxide" and the German Patent I 066 552 for the "oxide mixture".

example

Pure fiber-like, morphologically uniform polyoxymethylene is pre-crushed in a cutting mill and, after adding 10 to 35% of highly dispersed, inorganic oxides, mainly SiO2. AI ₂ O ₃ , TiC) ₁ . passed continuously through a blower mill, whereby a good splitting of the fiber bundles and an intimate mixing of fibers and oxides is achieved. The mixture of oxides and pure fibers is insoluble in all common organic solvents
The thickener is particularly suitable in polyester resins and varnishes. Epoxides or hydrocarbons (oils).

After adding certain amounts of the homogeneous mixture in different systems when dispersing over a three-roller, the griwi of the thickening when using the homogeneous mixture according to the invention (111) and comparative! For this purpose, a commercially available product (II), which also Polyoxymeihylenfaseffl (30%) ent- (0 Hull, soft have been prepared by Strahlenpolymerisation of trioxane, further comprising a through Strahlenpolymerisation (0.1 to O.Smegarad Sirahfungs · dosi *) of pressed trioxane A fiber as product obtained and mixed with (70%) highly dispersed silica was measured according to French patent specification 1,193,994 (IV) and a pure system to be thickened without a fibrous homogeneous mixture (!)

669 900

Conditions using a roiation viscometer at C and D = 2.72SeCf ¹

I. Filler mixture III IV Il 2.72 sec. ' cP at 0 = A. 1.6% in poly 150 8 500 4900 ester lacquer .... 4,500 B. 4.0% in 35,000 258,000 - Epoxy resin .. 67 118000 52,000 - C. 7.4% in oil. 40,000

Recipes

A. 20.0 g filler paste (8%), (3 χ three-roller),
61.6 g of an unsaturated, non-air drying one

Polyester resin with a styrene content of 34 percent by weight (Ludopal P®6 from BASF),
11.4 g monostyrene,
7.0 g paraffin solution (melting point 49 ° C),
(1% in styrene),

B. 50.0 g filler paste (8%), (3 χ three-roller),
50.0 g of a liquid epoxy resin on the base

of epichlorohydrin and diphenylolprop-n with an epoxy value of 0.48 to 0.57 (Shell Epikot _e ®828),

C. 50.0 g filler paste (10%), (3 χ Drejwalze),
18.0 g of a turbine oil for steam and water turbines according to DIN 51 515.

The viscosity rules listed in the table above show the clear superiority when using the hGdiogencn mixture according to the invention in terms of thickening capacity.
The thickening effect also changes with

ίο Storage for days at room temperature with access to air (moisture) not. The storage stability of the thickened products is very good, e.g. B. there was no change in viscosity after 3 months of storage thickened polyester varnish occurred.

Claims (1)

Claim: ίο using a homogeneous mixture (A) pure fiber, morphologically uniform, by catalytic polymerization of Polyoxymethylene obtained from trioxane and (B) 5 to 50 percent by weight of highly dispersed pyrogcn or oxides obtained by precipitation, mixed oxides or oxide mixtures of aluminum and / or titans and / or silicon as thickeners for polyester resins or lacquers. Epoxies or hydrocarbons.