DE1285175B - Use of polycarbonates for film production - Google Patents

Description

Because of their superior properties, films made from high molecular weight aromatic carbonate polymers have become increasingly important in recent years. For example, the carbonate polymer derived from bisphenol-A 2,2-bis- (4-hydroxyphenyl) -propane is used to produce films which have excellent color, clarity, high dimensional stability, high heat and acid resistance and high Have resistance to oxidative degradation up to temperatures of 160 ^° C. The high ignition point and the high aromatic content of the carbonate polymers have the consequence that the films made from such a material are resistant to burning; at thicknesses of more than 1 mm these foils are even self-extinguishing. Furthermore, polycarbonate foils can be easily welded, they are physiologically harmless and corrosion-resistant. These properties just described, together with the good electrical characteristics over a temperature range of −100 to 135 ° C., mean that films made from aromatic carbonate polymers are exceptionally well suited for a large number of technological applications.

However, polycarbonates also have the property of having a very high static coefficient of friction to own from slide to slide. This makes the handling of polycarbonate films more difficult, in particular, the use of such films in automatic processing devices heavily trimmed, such as in packaging machines where successful processing of on the premise that the coefficients of friction of the film are considerably lower than those of the conventional prior art polycarbonate films.

The subject of the invention is the use of polycarbonates of dihydric phenols in which in more thorough. Mixing particles of silicon dioxide, Talc or mixtures thereof have been incorporated, the particles having a have an average diameter of up to 10 microns and in an amount of 0.025 to 0.50 percent by weight, based on the total weight of the polycarbonate, are present for. Produce of foils.

The addition of the modifier to the polycarbonate can be done in any way, provided that it is properly distributed in the Polycarbonate is effected. For example, the mixing of the materials can take place at any normally method used to incorporate plasticizers or fillers in thermoplastic polymers using mixing rollers, other mixers, extruders, ribbon mixers, powder mixers and other mixing devices. The mixture obtained can then with the help of conventional Extrusion devices are extruded into films.

The films that are made from polycarbonate items according to the invention are through marked a haze value of less than 1%.

The modifying agents that are added to the aromatic polycarbonates are well known commercially available materials.
For example, the silica is commercially available in the form of fine particles with an average diameter of less than 10 microns. The talc which is useful in making the resin formulations of the present invention consists of a basic magnesium tetrasilicate of the formula

Mg ₃ Si ₄ Om (OH) ₂ .

This talc can be used either in its pure form or as talc coated with zinc stearate The latter are small particles of basic magnesium tetrasilicate of the aforementioned formula, which with zinc stearate, d. H. the zinc salt of stearic acid

[CH ₃ (CH ₂ ) I ₆ ] COOH

had been treated to have an atomic layer of zinc stearate on the surface of each To create talc particles. Thus, as indicated herein, the term talc includes both zinc stearate coated talc as well as the unmodified talc.

The carbonate polymers have repeating structural units of the formula

on, where A is a divalent aromatic group of the relevant dihydric phenol, which is in the Production reaction of the polymer was used, means.

The carbonate polymers preferably have an intrinsic viscosity (measured in p-dioxane in Deciliters per gram at 30? C), which is in the range of about 0.35 to 0.75.

The documents for the Belgian patent 642 285 relate to polycarbonates, which by the Addition of glass fibers can be improved. In contrast, the invention does not use glass fibers used if additives that are technologically completely different, namely silicon dioxide or talk. Furthermore, nothing is stated in the prior publication that glass fibers are any Have an effect on the coefficient of friction, so that for this reason the average person skilled in the art could not be suggested, silicon dioxide or to replace talc with completely different additives, for example with glass fibers, to the effect of lowering the coefficient of friction aimed at and achieved with the present invention to effect.

French patent 1 366 532 relates to the treatment of the surface of polycarbonate objects, for example of films, with a dispersion of silicon dioxide in water, a wetting agent and a chlorine-substituted organic Acid with the purpose of increasing the adhesive force of the surface with respect to a second film to enhance. In contrast, the present invention is for the purpose of silicon dioxide Incorporate a reduction in the coefficient of friction into the polycarbonate. So here are those already

Objectives opposed to each other. Another difference compared to the French patent specification 1,366,532, there is also the fact that in the case of the subject matter of the invention there is no water, no Wetting agents and no chlorine-substituted organic acid use. In the. Act would have Dispersion of these substances in polycarbonates has negative effects.

All parts and percentages in the following examples are based on weight, if nothing otherwise is said. The indicated average coefficient of static friction was determined by the test method ASTM-D-1894-63 determined. The haze percentage value was determined by the test method determined according to ASTM-D-1003-61.

The polycarbonates were prepared as usual by the fact that a carbonate polymer des 2,2 bis (4 hydroxyphenyl) propane, i.e. a bisphenol A polycarbonate, the desired amount one of the modifying agents is added, care being taken that a thorough distribution of the Modifying agent takes place in the polycarbonate. This is achieved by having the modifying agent in powder form to a small amount of the polycarbonate also in powder form adds and then for good through. mixture ensures. That little amount of mix is then added to the remaining large proportion of polycarbonate powder and then the premix thoroughly mixed in a ribbon mixer. The mixture obtained is dried and closed Deformed granules. The granulate is dried and shaped into films.

For the purpose of determining the coefficient of friction and the haze value, they were prepared Films subjected to various tests. The data obtained are in the following table summarized.

Additive concentration Particle size Thickness of the
tested film Coefficient of friction Turbidity value example Weight percent
of the additive in the (Micron) (mm) (%) none mixture - 0.025 10.0 0.3 SiOo Control ¹ ) 1.0 0.025 2.7 0.38 1 SiO ₂ 0.025 1.0 0.025 1.2 0.46 2 SiOo 0.050 1.0 0.075 0.72 0.47 3 SiOo 0.050 1.0 0.125 1.22 0.61 4th SiOo 0.050 1.0 0.175 2.0 0.88 5 SiOo 0.050 0.02 0.012 3.0 0.62 6th SiO ₂ 0.10 0.02 0.025 1.02 0.44 7th SiO ₂ 0.10 0.015 0.125 0.64 0.28 8th SiOo 0.25 0.02 0.10 0.975 <l, 0 9 SiO ₂ 0.25 0.015 0.025 2.4 0.303 10 SiO ₂ 0.25 0.015 0.025 0.815 0.98 11 Talk 0.50 <5 0.025 0.9 0.53 12th Talk 0.025 <5 0.025 Ul 0.78 13th Talk «) 0.05 <5 0.025 0.9 0.53 14th Talk «) 0.025 <5 0.075 0.91 0.31 15th • Talk «) 0.025 <5 0.019 2.0 0.68 16 Talk «) 0.05 <5 0.025 1.13 0.67 17th . Talk «) 0.05 <5 0.075 0.95 0.48 18th Talk «) 0.05 <5 0.175 0.75. 0.47 19th 0.05

') = Polycarbonate of 2,2-bis (4-hydroxyphenyl) propane.

") = Talc coated with zinc stearate was used in this example.

The invention enables the production of 55 capacitors and as a base for magnetic thin, self-supporting foils made possible, tapes suitable.

which have a useful haze value and a significantly lower coefficient of Static friction are characterized as the foils, which are made of polycarbonates of the state of f> o Technology to be produced.

The films that are produced from the preparations according to the invention have a very high Wide range of uses as drawing films, as packaging and wrapping material. Further These foils are very good for use as electrical insulating tapes, as foil dielectrics for

Claims (1)

Claim: Use of polycarbonates from dihydric phenols, in which in thorough mixing Particles of silicon dioxide, talc or mixtures thereof have been incorporated with the particles having an average diameter of up to 10 microns and in an amount of 0.025 to 0.50 percent by weight, based on the total weight of the Polycarbonates, are available to manufacture of foils.