CS205846B1 - Polypropylene with improved mechanic and low-temperature properties - Google Patents

Description

. SUMMARY OF THE INVENTION The present invention relates to polypropylene having improved mechanical and low temperature properties, in particular notch toughness and frost resistance.

Polypropylene, due to its chemical and physical structure, is a material with good mechanical and electrical properties. It has a low weight and good chemical resistance. Sirgium is prevented from low toughness and low temperature characteristics, especially frost resistance ·

In principle, the toughness of polypropylene can be influenced in several ways. Among the best known are copolymerization of propylene with another monomer (U.S. Pat. No. 3,929,932) and admixture of elastomers into polypropylene (Kryezewski M. et al., J. Apl. Polym · Sci ·,

12, 1971, p. 5, 1139-1117).

While this improves the impact properties of polypropylene, it is at the cost of increased production costs.

The polypropylene according to the invention has improved mechanical and low temperature properties, in particular notch toughness, frost resistance, polymer chains oriented to fibrillar structures, and contains fibrous structures. 0.01 to 2.0% by weight of modifying additives based on inorganic or organic sulfur or nitrogen compounds, and a melting point higher than the melting point of the crystalline phase, insoluble in the polymer m e, and not degrading ea under the polypropylene processing conditions.

These additives modify the supersolecular structure of the polypropylene so that, in the crystallization of the polymer melt, they prefer the formation and formation of a crystalline structure, usually fibrillar, with better impact resistance and low temperature properties than the supersolecular structure of the original unmodified polypropylene. As a result of the formation of such a structure, more energy is needed to break the polymer sample under mechanical stress, while improving the elastic properties of the polypropylene, thereby improving notched impact strength and frost resistance.

Suitable additives are inorganic (oxides) and organic substances, in particular compounds containing dithiocarbamine - N - C-S - which are bonded via a sulfur atom

With ionic or covalent coupling with a metal atom, preferably zinc, e.g. zinc diethyldithiocarbamate, imides of dicarboxylic and dithiocarbonic acids, in particular aromatic, in which hydrogen on the nitrogen is substituted by a metal atom, e.g.

C-S-C-SH, C-NH-C-SH, C-S-OS, C-NH-C = S \ II \ II \ I I

C-N C-NH C-NH C-NH

205 840 mainly 2-aercaptobenzimidazole and its derivatives, for example · 2-mercaptobenzimidazole zinc · Additives have a melting point above the melting point of the crystalline phase of polypropylene and do not degrade and under polypropylene processing conditions ·

Polypropylene modified according to the present invention may be used in new application coatings. For example, injection molded articles, containers, fibers, and other articles may be used in harsh climatic conditions and low temperatures, under high dynamic stresses and under high stress.

The polymeric material derived from polypropylene waste can also be modified with the additives of the present invention, thereby providing better performance properties and thus a broader field of application.

The actual modification of the polypropylene according to the invention is economically unpretentious and technically easy to implement on a mechanical-technical device which is used in conventional polypropylene plants.

Example 1

The effect of PP modifiers and reflection on impact properties was found on commercially produced polypropylene Tatran PD - 14.0 with IT 3.3 g. 10 min · / measured according to ČSN 64 0861 / with specific gravity 0,91 kg. The modification of the base polymer is carried out by homogenizing PP powder containing 0.25% by weight of 2-mercaptobenzimidazole and then granulating it *.

Notch toughness specimens are prepared on a CS 195 injection molding machine under the following conditions: heating zone temperatures of 210 ° C, 220 ° C, 23 ° C; nozzle temperature 220 ° C, melt hydraulic pressure 15 MPa, working cycle 55e.

Notch toughness of comparative and modified PP samples is determined by the Charpy method according to ČSN 64 0612 ·

The low-temperature properties of PP aa are proven on an ergometer! according to CSN design Measurement of resistance of plastics to low temperatures / former PND n.p · Slovnaft no. 25,370 /.

Telescopes for ergometric determination of frost resistance aa prepared by hand cutting

of the construc - tion 1 mm thick boards pressed under the following conditions: preheating 2 mins · pressing 3 mins · cooling 5 mins · temperature 250 ®C pressing pressure 25 MPa Smoothing pressure 25 MPa

205 046

It uses a mixture of acetone and dry Back as a cooling medium.

The notched toughness of the modified polypropylene is 4.0 kJ m, not modified

2.6 kJ m ² .

The frost resistance of modified polypropylene is - 35 ° C and unmodified - 15 ° C «

Example 2

Polypropylene as in Example 1 A modification of the polypropylene powder and is made up to 0.8 wt. Potassium phthalimide followed by granulation Telieaka for mechanical testing and frost resistance measurement are prepared and tested as in Example 1.

The notched toughness of the modified polypropylene is 5.5 kJ m- ² , unmodified

2.6 kJ m ² .

The modest resistance of the modified polypropylene is - 70 ° C, the unmodified polypropylene is - 15 ° C.

Example 3

Polypropylene as in Example 1. The modification of polypropylene a and with 0.5% by weight of Hermat ZDK (zinc diethyldithiocarbamate) followed by granulation. Bodies for mechanical ecus and ergometric assays are prepared as in Example 1.

The notched toughness of the modified polypropylene is 4.4 kJ and unmodified 2.6 kJ m ² .

Frost resistance of modified polypropylene is - 60 ° C, unmodified is - 15 ° C ·

Example 4

Polypropylene ake in Example 1, the modification of polypropylene aa carried out β 1.2 wt% BaSO 4 followed by granulation.

The notched toughness of the modified polypropylene is 4.1 kJ m ² , unmodified

2.6 kJ m ² .

Frost resistance of modified polypropylene is - 30 ° C, unmodified is - 15 ⁰ C ·

Example 5

Polypropylene as in Example 1, the modification of polypropylene is carried out and 0.9 wt

2 & / NO3 / 2 followed by granulation.

20S 848 "

Notched modified polypropylene is 3 7 7 kJ unmodified

2.6 kJ m ² .

The modified resistance of the modified polypropylene is - 25 ° C, the unmodified is - 15 ^e C.

Claims (1)

Polypropylene has improved mechanical and low temperature properties, preferably enhanced, notched impact, frost-resistant, and polymeric chains oriented to a fibrillar structure, characterized in that it comprises 0.01 to 2.0% by weight, and preferably 0.7 to 1, 2 wt. modifiers based on inorganic and / or organic sulfur and / or nitrogen compounds, and a melting point higher than the melting point of the crystalline phase, insoluble in the polymer melt and non-degrading and under the conditions of polypropylene processing.