DK141073B - POLYMID FILM OF POLY-EPSILON-CAPROLACTAM AND PROCEDURES FOR PRODUCING THEREOF - Google Patents

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Vfia / OD PRESENTATION 1U1073 C 08 L 77/02 DENMARK "" ln, c | i® ®J J 5 / i | '(21) Application No. ^ 799/75 (22) Filed on Dec. 24. Otct. ί975 (23) Race Day Oct. 24 1975 (44) The application presented and ", oy_, qoa the presentation thesis published on (·)

DIRECTORATE OF

PATENT AND TRADE MARKET (30) Priority requested from it

Oct 25 1974, 2450776, DE

Oct 25 1974, 745576Ο U, DE

(71) BISP MTIENGESELLSCKAPT, Carl-Bosch-Strasse 58, 6700 Ludwigshafen, DE.

(72) Inventor: Erwin Zahn, Edenkobener Strås se 1, 67ΟΟ Ludwigshafen, DE:

Claus Cordes, HaTbergstrasse 15 »6719 Weisenheim, DE: Franz Zahrad = nik, Schwedlers tr as s e 120, 67ΟΟ Ludwigshafen, DE: Hans-Peter ~ Veiss, Moltkestrasse 58, 6701 Altrip, DE.

(74) Authorized in the course of the proceedings:

Hofman-Bang & Boutard. (64) Poly-epsilon-caprolactam polyamide foil and its method of manufacture.

The invention relates to a polyamide film and to a process for making it.

Polyamide films exhibit extremely favorable properties. Thus, e.g. excellent mechanical strength, excellent toughness, high through * impact strength and high abrasion resistance. The surface of the films is distinguished by their brilliance, surface hardness and printability. The films have a high transparency and are grease, oil and cold resistant. In addition, the films are characterized by aroma, gas and vacuum tightness, they are capable of freezing and free of harmful or contaminating foreign substances. Because of these, polyamide foils find extremely beneficial properties for technical application and are especially preferred as packaging material.

Admittedly, for commercial production of thin polyamide films with high quality processing and application properties, high molecular weight polyamides whose viscosity fraction is usually between 3.8 and 4.5 have so far been required. This is a disadvantage because the preparation of these higher molecular weight polyamides is clearly more difficult and more time consuming than the production of the smaller high molecular weight polyamides. Thus, e.g. poly-, caprolactam up to a viscosity fraction of approx. 3.1 is prepared by a one-step process of polycondensation in the melt, while in order to obtain products with higher viscosities two steps must be taken, whereby the polymerization in the melt results in a solid phase polymerization. In addition, certain cumbersome production apparatus are necessary and the required condensation times in the solid phase amount to a multiple of the required condensation times in the melt. Finally, a further disadvantage of the production of polyamide foils is also that high melting temperatures are required in the processing due to the high molecular weight polyamides needed so far.

It is an object of the invention to provide a thin polyamide film having excellent processing and use properties and of the kind set forth in the preamble of claim 1, whereby a polyamide having a lower viscosity fraction than those previously used in the manufacture of thin polyamide films can be used. with high-quality processing and use properties, as well as a process for making them.

The polyamide foil of the invention, which is of the kind set forth in the preamble of claim 1, is characterized by the feature of the characterizing part of claim 1. Surprisingly, it has been found that the object of the invention is fulfilled.

It is well known from Danish Patent No. 99,483 a linear polyamide which is stabilized against the effect of heat and light by the addition of a silicate of Group II-IV metal in the periodic system. However, the range of crystalline magnesium silicate content used in the film web of the invention is completely outside the range, namely 0.05-2% by weight, exemplified and preferred by Danish Patent No. 99,483. In addition, neither the relatively low viscosity of the polycaprolactam, the particle size of the magnesium silicate, nor the thickness of the film web used according to the invention is disclosed in Danish patent no.

99,483.

The invention also includes a process for making this film, which is characterized by the characterizing part of claim 2.

The polyamide films of the invention and the films made according to the process of the invention are characterized by excellent use and processing properties, such as e.g. machine machinability, whereby machinability is understood both by the foil's conditions during manufacture itself and in the machines for further processing. The particularly good ability of the films for lamination and printing must be highlighted. There are special advantages to lamination due to the high processing speeds that can be made large and, as a result, to the film's interference-free passage. In addition, the high transparency and brilliance of the films must be mentioned. Since the process of the invention allows one to operate at lower melting temperatures than the usual high molecular weight polyamides, the formation of degradation products is reduced and the purification intervals of the machine elements coming into contact with the melt may be required.

In the practice of the method according to the invention one can use worm extruders known per se which are provided with wide gap nozzles. This usually involves working at product temperatures between 200 and 300 ° C. The extruded films are taken over by a cooled recording roller, where they solidify and become solid, and then are transported over transfer rollers for winding or further processing.

141073 4

Magnesium silicates, mainly naturally occurring crystallized magnesium silicates, such as e.g. minerals from the $ erpentine group or fibrous crysotylasbest or talc.

White or very light minerals that contain small amounts of contaminants are preferred. Naturally occurring crystalline magnesium silicates with a ratio of MgO to SiCl3 between 1: 1 and 1: 3 with a water content of less than 20%, with less than 0.5% Al 2 O 3, below 0.5%

FeO and less than 5% calcium carbonate have been found to be particularly advantageous. The mineral additives must be very regularly distributed in the polyamide and must not form any agglomerates. The size of the individual particles must be less than 20 µm. This means that at least 99% of all particles have a size <30 µm.

In a particular embodiment of the method, the particle size is kept below 10 µm. The required concentrations are between 0.001 and 0.01% by weight.

The polyamide used has a viscosity fraction of less than 3.3, but Qver 2.4. In a particularly advantageous embodiment, the viscosity fraction has a value between 2.5 and 2.8. The viscosity fraction is hereby determined by the ratio of the throughput times of 1 percent solutions of the 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 advantageous embodiment of the process, poly-caprolactam is produced which is produced exclusively by polycondensation in the melt without subsequent solid state condensation. Despite these low viscosities, surprisingly high production rates can be achieved. In the method according to the invention, the prepared films are pulled at speeds exceeding 30 m / minute from the cooling roll. In a particularly preferred embodiment, the extraction rate of the film produced exceeds 50 m / minute. The temperature of the cooled recording roller must be between 80 and 130 ° C. Rolling temperatures between 90 and 100 ° C have been found to be particularly advantageous.

In the polyamide foils and in the process according to the invention, as mentioned, other additives known in conjunction with polyamides can also be used, which in a known way improve the properties of the foils produced. Thus, the polymeric starting materials used may e.g. contain stabilizers, light preservatives, waxes, dyes and pigments, or they may also be added first in the manufacture of the foil.

EXAMPLE 1

To carry out the experiment, an extruder from the company Barmag with a diameter of 90 mm and a length of 25 D. was used. The extruder was equipped with a three-zone screw with a division of 7: 3: 15 D. The compression ratio was 14: 4,5 · As wide gap nozzle was used a commercially usual nozzle from the company Johnson to a width of 800 mm. The temperature in the individual heating zones of the cylinder varied as one began with the entry zone, 185 ° C, 200 ° C, 250 ° C, 23 ° C, 230 ° C, 240 ° C. Adapter and nozzle were kept at a temperature of 240 ° C. The screw speed was 45 rpm and the temperature of the cooled recording roller for the extruded polyamide film was 95 ° C. The worm was provided with granulated poly-caprolactam, which had a viscosity fraction of 2.6, containing 25 x 10 6 S talc with a particle size of 10 µm in fine distribution via the filling funnel. The foil was drawn to a thickness of 25 µm.

At ejection of 83 kg / h, extraction rates of the foil of 50 m / min were obtained. The film was flawlessly peeled and wound at this speed, it was highly transparent and capable of forming a flawless plane. The manufactured foil was printed without interruption at high processing speed.

The following Examples A and B are comparative examples. They must show that usable polyamide foils with high extraction velocity can only be produced when all the technical precautions specified in the characterizing part of claim 1 are used. In Example A, a polycaprolactam with a viscosity fraction of 4.0 was used, which required processing temperatures above 250 ° C. If, as in Example B, one tries to process lower molecular weight polycaprolactam (viscosity fraction 2.75) without magnesium silicate, only lower extraction rates can be used and no usable foil is produced.

141073 6 Example a

The same test system was used in the same device as in Example 1. The temperature in the individual zones of the cylinder varied, starting from the pull-in zone, 205 ° C, 220 ° C, 250 ° C, 250 ° C, 250 ° C, 260 ° C. Adapter and nozzle were kept at a temperature of 260 ° C. Via the filling funnel of the extruder, poly-caprolactam with a viscosity fraction of 4.0 was added. At a film thickness of 25 µm, the maximum extraction speed of the film was 35 m / minute. The foil produced was printed without interruption at high processing speeds.

EXAMPLE B

The same test plant was used in the same device as in Example 1. In the heating zones of the cylinder, the adapter and the nozzle the same temperatures were set as in Example 1. Poly-caprolactam having a relative viscosity of 2 was filled via the filling funnel of the extruder. , 75 · At a film thickness of 25 µm, the maximum possible extraction speed of the film was 25 m / minute. At these extraction rates, the foil caused frequent disturbances and did not produce any flawless, smooth coil winding.

The foil did not print flawlessly at the usual production rates.