FI62117C - FOLIEBANA AV POLY-EPSILON-KAPROLAKTAM ELLER EN EPSILON-KAPROLAKTAMSAMPOLYMER - Google Patents

Description

E3F71 [B] (11) NOTICE OF PUBLICATION ^ Λ Λ 1 JNETa l JV 'UTLÄGGNI NGSSKRIFT 1' fc (45) Patent granted 10 11 1932 Patent oeddelat (51) K * .ik? /Int.a3 C 08 K 3/34, C 08 L 77/02 FINLAND —FINLAND (21) Fhtcnttlhakemw · - PKcntarwOknlni 75285 ^ (22) Hekemltpilvt - AnaBknlnpdat lU. 10.75 (23) Alkwpllvt — Glhlfhaud ·! lh.10.75 (41) Tulhit lulklMkil - BIlvK offemllf 26.0h.j6

National Board of Patents (44) NihtivUuiptnon | -

Patent- och refisterstyrelMn 'AnatMun utlkgd och ut (. * Krlft * n pubileared 30.07 · 82

(32) (33) (31) Requested otuotkou * - Begird priority 25.10.7U

25.10.7 ^ Federal Republic of Germany-Förbunds-republiken Tyskland (DE) P 21 + 50776.U, G 7 ^ 35760.1 (71) BASF Aktiengesellschaft, 67ΟΟ Ludwigshafen, Federal Republic of Germany-Förbundsrepubliken Tyskland (DE) (72) Ervin Zahn, Ludvigs Claus Cordes, Weisenheim, Franz Zahradnik, Ludwigshafen, Hans-Peter Weiss, Altrip, Federal Republic of Germany FÖrbundsrepubliken Tyskland (DE) (7M Oy Kolster Ab (51+) Foil sheet of poly-? -Caprolactam or fc-caprolactam copolymer - Folieban This invention relates to polyamide films.

Polyamide foils have the most advantageous properties. Thus, for example, they have superior mechanical strength, excellent toughness, high penetration strength and tear strength. The surface of the foils is characterized by gloss, surface hardness and suitability for printing. The foils have good transparency and are resistant to grease, oil and cold. Furthermore, the foils are characterized by aroma, gas and vacuum resistance, can be cooled to low temperatures and are free of harmful or suspicious by-products. Due to these advantageous properties, polyamido foils have a wide range of uses in technical applications and are particularly preferably used as a packaging material.

However, the industrial production of thin polyamide films with first-class processing and use properties has so far required high-molecular-weight polyamides, the relative viscosities of which generally range from 3.8 to 4.5. This is detrimental because the preparation of these high molecular weight polyamides is clearly more difficult and more time consuming than the preparation of lower molecular weight polyamides. Thus, for example, poly-ε-caprolactam can be prepared to a relative viscosity of up to about 3.1 by a one-step process by polycondensation in the melt, while higher viscosity products must be prepared in two steps, with melt polymerization involving solid phase polymerization. This requires special consumable production equipment, and the required solid phase condensation times are many times greater than the melt condensation times. Finally, an additional disadvantage in the production of polyamide films is that the high molecular weight polyamides used so far require high melt temperatures in further processing.

The invention was therefore based on the object of producing the said disadvantages while avoiding thin polyamide films which have first-class processing and use properties.

Surprisingly, it was found that this object can be solved with a foil sheet according to the invention. This foil sheet is characterized in that it consists of a polycaprolactam having a relative viscosity of 2.4 to 3.3, preferably 2.5 to 2.8, containing 0.001 to 0.01% of crystalline magnesium silicate having a particle size of less than 30, evenly and finely divided , wherein the thickness of the foil sheet is less than 50.

The foils of the invention are made by a process for preparing single or multi-layer sheet foils from copolymers of poly-ε-caprolactam or more than 70% caprolactam thereof by extruding melt through a slit nozzle onto a cooling roll and subsequently drawing the formed foil that a caprolactam having a relative viscosity of 2.4 to 3.3, preferably 2.5 to 2.8, containing 0.001 to 0.01% of naturally occurring crystalline magnesium silicate having a particle size of less than 30 microns is uniformly and finely divided, and the melt from the slit nozzle is drawn at a drawing speed of more than 30 m / min from the cooling roll into a foil with a thickness of less than 50.

The foils according to the invention are characterized by excellent use and processing properties, such as, for example, suitability for machines, whereby suitability for machines is understood as both the behavior of the foil in the manufacture itself and in further processing machines. It should be noted that the foils are very suitable for lamination and lamination due to the possible high processing speeds and the smooth flow of the foils. It is further worth mentioning the high transparency and gloss of the foils made according to the invention. Since the method of manufacturing the foil sheet according to the invention 3 621 1 7 allows working at lower melt temperatures than hitherto conventional high molecular weight polyamides, the formation of disintegration products is reduced and the cleaning interval of the machine parts in contact with the melt can be extended.

In carrying out the method, screw extruders with slit nozzles known per se can be used. In this case, work is usually carried out at product temperatures of 200-300 ° C. The extruded films are received by a cooled receiving roller, whereby the films are stiffened and strengthened and finally transported through guide rollers for rolling or further processing. The method of manufacturing the foil sheet according to the invention is also excellently suitable for implementation with tandem devices, in which case the obtained thin polyamide foils can be combined with layers of other materials, for example polyethylene foils.

The magnesium silicates used are mainly naturally occurring crystalline magnesium silicates, such as, for example, minerals of the serpentine group or fibrous chrysotile asbestos or talc. White or very bright minerals containing only small amounts of impurities are preferred. Particularly preferred are naturally occurring crystalline magnesium silicates with a MgO: SiO2 ratio of between 1: 1 and 1: 3, a water content of less than 20%, less than 0.5% Al 2 O 3, less than 0.5% Fe 2 O and less than 5% calcium carbonate. The mineral supplements must be very evenly distributed in the polyamide and must not form agglomerations. The size of the individual particles should be less than 30 pm. It must be understood that at least 99% of all particles have a size <C 30 pm. In a particular embodiment of the invention, the particle size is kept below 10. The required concentrations are between 0.001 and 0.01% by weight.

The polyamide used in the foil sheet according to the invention has a relative viscosity of less than 3.3. In a particularly preferred embodiment of the invention, the relative viscosity is between 2.5 and 2.8. The relative viscosity is then determined from the ratio of the throughputs of 1% solutions of polyamide in 96% sulfuric acid to the throughput time of pure 96% sulfuric acid in a capillary viscometer at 25 ° C.

In a further particularly preferred embodiment of the invention, poly-β-caprolactam is used, which is prepared by polycondensation alone in the molten without subsequent condensation in the solid state. In addition to pure polycaprolactams, 4,621,117 polymers containing up to 30% of other comonomers can be used. Surprisingly, despite these low viscosities, very high production rates can be achieved. In the method of manufacturing the foil sheet according to the invention, the prepared foils are drawn from a cooling roll at a speed of more than 30 m / min. In a particularly preferred embodiment of the invention, the produced foil has a drawing speed of more than 50 m / min. The temperature of the cooled take-up roll should be between 80 and 130 ° C. Roller temperatures of 90 to 100 ° C have proven to be particularly advantageous.

In the process for the production of the foil sheet according to the invention, other additives known for polyamides can also be added, which in a known manner improve the properties of the foils produced.

Thus, the polymeric starting materials used may contain, for example, stabilizers, sunscreens, waxes, colorants and pigments, or these can also be used only in the production of foils.

Example 1

To perform the experiment, an extruder manufactured by the company name Barmag with a diameter of 90 mm and a length of 25 D was used. The extruder was equipped with a three-zone screw conveyor with a pitch of 7: 3: 15 D. The compression ratio was 14: 4.5. The slit nozzle was normally a commercially available Jahnson 800 mm wide nozzle. The temperatures of the individual heating zones of the cylinder were starting from the inlet zone 185 ° C, 200 ° C, 230 ° C, 230 ° C, 230 C, 240 ° C. The screw rotation speed was 45 rpm, and the temperature of the cooled receiving roll of the extruded polyamide foil was 95 ° C. Granular poly-ε-caprolactam having a relative viscosity of 2.6 and containing 25 parts per million of talc having a particle size of c 10 μm, finely divided, was fed to the screw conveyor through a hopper. The foil was drawn to a thickness of 25. With a production of 83 kg / h, a foil drawing speed of 50 m / min was obtained. The foil could be pulled and rolled flawlessly at this speed, the foil was very transparent and flawlessly flat. The prepared foil could be layered with a polyethylene foil and printed without interference at a high processing speed.

Example 2 The same test apparatus was used in the same manner as in Example 1. The temperatures of the individual zones of the cylinder starting from the inlet zone were 205 ° C, 220 ° C, 250 ° C, 250 ° C, 250 ° C, 260 ° C. The adapter and nozzle were maintained at 260 ° C. A relative viscosity of 4.0 was added via the extruder hopper

O

poly-C caprolactam. With a foil thickness of 25 μm, there was foil