CS205693B1 - Filling for the polyvinylchloride with the stabilization effect - Google Patents

Description

In the chemical treatment of magnesites and dolomites, calcium carbonate containing precipitated ammonium nitrate and magnesium carbonate is formed as a by-product. Due to the ammonium nitrate content, there was no use for this product other than as fertilizer or compost addition, although precipitated calcium carbonate is the desired filler for polyvinyl chloride (PVC).

Surprisingly, it has now been found that ammonium nitrate and nitrate anions generally do not degrade calcium carbonate as a filler in PVC, but on the contrary increase the thermal stability of the composite and even this favorable stabilizing effect is added to the stabilizing effect of other commonly used thermal stabilizers.

The thermal stability of PVC is not sufficient for the polymer to be processed without thermal decomposition, which is manifested initially by the formation of a yellow to brown-black color, accompanied by later cleavage of hydrogen chloride. Therefore, thermal stabilizers are used which are capable of preventing undesirable discolouration and the development of hydrogen chloride for a certain period of thermal stress. The most common thermal stabilizers include organic salts of calcium, barium, cadmium, organotin compounds, lead compounds, nitrous acid salts, phosphorous salts, organic epoxides and many other organic and inorganic compounds. The salts of nitric acid are not known thermal stabilizers and therefore the stabilizing effect of their admixtures in the mineral filler (calcium carbonate) is quite surprising. A similar stabilizing effect can also be achieved by additionally adding a salt of nitric acid to the mineral filler based on calcium and / or magnesium carbonate.

SUMMARY OF THE INVENTION The present invention relates to a calcium and / or magnesium carbonate stabilizing filler for polyvinyl chloride containing 0.1. up to 7% by weight of nitric acid salts.

The filler according to the invention is prepared by precipitation of calcium and magnesium cations from solutions containing nitrate anions with carbon dioxide by known methods so that the particle size of the filler is 50 µm and 2 µm.

Another possibility of preparing the filler is by mixing calcium and / or magnesium carbonate with nitrates such as ammonium, sodium, potassium, calcium, barium, cadmium or lead.

The composite may contain, in addition to the PVC and the filler according to the invention, filler surface modifying components or increasing the toughness of the composite, e.g. fatty acids, polyethylene, copolymer, ethylene-vinyl acetate or chlorinated polyethylene, where the effect is added to the stabilizing efficiency of the nitrate anions.

It is also possible to surface the filler according to the invention with impregnation with fatty acids, if necessary with ethylene vinyl acetate copolymer and other known methods.

208 083

The objective measure of the stabilizing effect of PVC thermal stabilizers is the congopaper method according to DIN 53 381, which indicates the start of the release of hydrogen chloride ^{from the} PVC powder heated to a constant temperature in a closed tube.

Another way is to determine the thermal stability on a tape thermal stability meter, where ί is monitored for the yellowing time of the PVC film heated to constant temperature.

The invention is illustrated by the following examples, which are not intended to limit or limit the invention in any way. Parts and percentages given in the examples are by weight.

Example 1

To monitor the effect of ammonium nitrate on the thermal stability of PVC mixtures, the congopaper method according to DIN 53 381 was used. The mortar was prepared by carefully mixing the mixture, the composition of which is given in Table I.

Table I Ident. PVC ¹ > mixtures 2) CaCO ₃ . O ° h £) EVA ^{3 4 5} > Stabilizer Sn ^ Stabilizer Pb ^{6 7} > Stabilizer epoxy 1 100 ALIGN! '- - - - - 2 100 ALIGN! - - - - 3 3 100 ALIGN! - - - 1,5 · - - 4 100 ALIGN!  - - - - 1.5 - '5 77 23 - - - - - 6 74 22nd - 4 - - - 7 77 23 - 7 1.5 - - 8 74 22nd - 4 1.5 - - 9 77 23 - - - - 3 10 77 23 - - - 1.5. - 11 77 ' - - 1.5 - - ' 12 77 20®} 3 ⁸ 1.5 t 1) Vestolit 6 558. 2) Sooal U 1 , laboratory impregnated with 6% stearic acid.

3) Magnesium carbonate Pure, laboratory impregnated with 6% stearic acid.

4) EVA ethylene-vinyl acetate copolymer containing 32% vinyl acetate groups. GDR Miravithen D 47 XA, applied to the surface of the filler while hot,

5) Organo-tin stabilizer Irgastab 17 M0.

6) Lead stearate.

7) Butyl ester of epoxystearic acid.

8) Laboratory sample prepared by precipitation of a solution of calcium nitrate, magnesium nitrate and ammonium nitrate with ammonium carbonate in an ammonia medium. Obtained filler

205,633 contained 15% magnesium carbonate and 0.8% ammonium nitrate. The filler was impregnated with 6% stearic acid.

To these mixtures, ammonium nitrate was added in a mortar and the mixtures were perfectly homogenized. The thermal stability, as measured by the congopaper method, is summarized in Table II. The measure of stability is time - expressed in minutes; needed to liberate hydrogen chloride at 190 ° C to color the blue congopaper.

Table II

Mark. mixtures 0% Ammonium nitrate in% 0.2% 0.4% 0.6% 0.8% 1% 1 2 7 - 8 8 - 2 • 4 - - 15 Dec - 3 23 19 Dec 20 May 21 21 21 4 23 16 - 18 19 Dec - 5 17 32 46 59 66 75 6 11 33 43 55 62 69 7 42 86 113 152 228 268 8 41 51 70 91 116 ' 133 9 50 - - 84 - - 10 46 - - 105 - - 11 38 75 ¹ ) - 93 - - 12 - - - - -

1) Ammonium nitrate was not additionally added to the mixture, but was incorporated into the filler particles upon precipitation.

Example 2

Similarly, the thermal stability of the potassium nitrate-containing compositions was measured. The denomination of the compounds is taken from the enclosed. The thermal stability, measured as in Example 1, is shown in Table III.

Table III

Mark Amount of potassium nitrate in% of the mixture 0% 0,2% 0,4% 0,6% 0,8%.

2 4-6, .7

41 44 - 52 51

Claims (1)

Object of the invention A filler for a polyvinyl chloride having a stabilizing effect on the base of calcium and / or magnesium carbonate, characterized in that it contains 0.1 to 7% by weight of nitric acid salts.