DE1495420A1 - Method and apparatus for producing polyamide molded bodies, such as rods, strips, tubes, molded bodies of any profile, and the like. by alkaline polymerization - Google Patents

Description

Method and device for the production of polyamide moldings, like @ 3 @ rods, strips, tubes. Moldings of any profile and the like. By alkaline Polymerization The present invention relates to a method and an apparatus for the manufacture of profiled polyamide moldings, such as rods, strips, tubes, Moldings of any profile and the like. By alkaline polymerization of lactams. According to the invention, the moldings or semi-finished products mentioned can be of any length be generated.

The previously known methods by which such molded bodies are it fibers, threads, rods, tubes, tapes or the like, made of polyamides continuously getting produced. go from finished polymers and the deformation must therefore at temperatures above or at least close to the melting point of the polyamide vorgsno @@ en.

Even if the production of the polymerisute directly with a continuous Deformation is coupled, one always assumes this deformation of the high molecular weight, fully polymerized or condened polyamides, regardless of which processes and which catalysts are used.

For example, a so-called fully continuous process is used carried out with non-alkaline catalysts in such a way that a polymerizing, or polyconensating @aprolactam melts in a polymerization tube continuously moved towards an outlet and, after the polymerization has ended completely the polyamide formed from this opening is at or above the melting temperature shed or spun into fibers at the necessary temperatures around or at 2700C, and residence times, calculated from the introduction of the Monomers up to the removal of the polymers, of 10 and more hours are required. So here one takes eo serious ones to enable continuous work Disadvantages, such as high working temperatures, high working pressures, high energy consumption as well as preload caused by the long thermal treatment and partially undesired change in the polymer in Kaufo Compared to these older polymerisation or polycandeation process, it was to be described as an important advance, when it became known that it is possible with the help of alkaline catalysts and more suitable Activators within a few minutes, starting from lactams to high molecular weight Polyamides to arrive. The working temperatures are above this in this process the melting point of the lactams used, but generally remain below of the melting point of the polyamides being formed The melting point of the polyamides can but also at the beginning or during the exothermic reaction are only exceeded in this case also the continuous processing of this polyamide melt possible, while with alkaline rapid polymerization below the melting point of the polyamide formed could only be worked discontinuously so far. @ In industrial production, polyamide granules or chips are used today from which at temperatures around or above the melting point of the polyamides lying, melted or softened in extruders or extrusion presses and directly subsequently be deformed. Because of the small temperature interval between the Slabs and melts are involved in the processing of polyamides with such machines special arrangements and constructions are necessary. In general, high pressures are special control devices, special temperature controls and under certain circumstances Protective gas atmosphere required.

The present invention has now set itself the task of a method and to create a device that enables profiled shaped bodies, such as Poles. Tapes, pipes and moldings of any profile continuously under utilization the alkaline rapid polymerization of lactams. It must be considered very Surprisingly, it is said that, according to the invention, this is below the melting point of the polymide that forms can remain and thereby a number of those listed above Avoids cons, It was. namely, a method and apparatus for manufacturing of profiled polyamide moldings, such as rods, strips, tubes, moldings any Profiles and similar by means of an alkaline rapid polymerization of lactams with six or more than six carbon atoms found in the lactam ring, the The method is characterized in that one is in two heated agitator vessels one or more lactams melts, the one melt the catalyst, the others contain the actuator, these melts, each of which for itself at least stable for several hours, doh. not or only under the given conditions slowly polymerizes, by metering devices in on the concentration of the activator and catalyst continuously combined in the melt-dependent proportions and mixes this combined melt continuously to a molding machine fed, the polymerization at a temperature above the melting point of the lactam but below the melting point of the polyamide being formed and then in the shape geo-machine at by the exothermic reaction and possibly increasing by active heating, but always below the melting point The temperature of the formed polymide can run down and the formed feete Profile stucco is continuously withdrawn from the shaping zone by active pulling can be used as a metering device, e.g. continuously variable gear pumps0 One Apparatus for performing the method is shown in the figures. This device is characterized in that one below the other, one above the other or the following sub-devices are arranged one behind the other: two parallel-connected, heated and closed melting devices (1), each with a feed device, RUhrterk and Schutsgaszuleitung, one connected to each Aufachmelzvorrichtung Do-Si device (2), then a common mixing device (3), subsequent Shaping device (4) with a not shown. th shaping zone, a Extractor tube (not shown), associated temperature control devices, protective gas To (11) and discharge (12) valves, furthermore a withdrawal device (5), a post-heat treatment (6) and finally a cutting or length-cutting device (7) e The shaping device is shown in Fig. 2 in several, for example in the independently thermostatically controlled sections (8), (9) and (10) divided and has a Be (11) - and a degassing valve (12) for supply and discharge of the Protective gasesa Within this illustrated device are a large number of Variations in the details of the apparatus are possible.

When the two melt components come together in the mixing device (3) and further in the shaping device (4), the polymerization of the begins Lactams, the rate of polymerization mainly due to that in the Melt prevailing temperature was influenced. The polymerization itself runs under uniform, defined conditions abO The starting temperature of the melt depends on the profile shape and the desired polymerization rate chosen. Low melting temperatures result in longer gel times (liquid times) in the upper part of the shaping zone, enable intensive mixing and good ventilation and smooth drainage, even of irregularly shaped profile pieces. but will in the subsequent Part of the additional energy suggests, so the polymerization comes in quickly there too Gear and a final temperature of 180 to 190 ° C is safely reached To "start up" the system is first of all the lower outlet opening of section (10) (Fig.2) of the shaping device (4) (Fig. 1 or 2) closed with a suitable plug or this one inserted in a suitable place of the Rohrea0 Er wlra guided and held via an extension through the trigger device (5) Here and in the following the prerequisite is made, for example, that the The melt is introduced into the shaping device from above through the valve (11) (Fig.2) with partial opening of the other valves, the entire Adequate system parts flushed with an oxygen-free @ protective gas ff ", in order to displace all existing atmospheric oxygen. Nitrogen is used as a protective gas preferred.

When the vent valve is open and after the target temperature has been reached Catalyst or activator are added to the agitator tanks Melting in suitable conditions via the mixing device through the dosing device or pumps conveyed into the shaping zone, this pipe is bæwO der upper part of the same from bottom to top facing down above the respective level of the Stopper is charged with melt as soon as the tube is filled, depending on the location of the stopper, the degassing valve (12) in question is closed and now by means of the dosing devices (gear pump0 pressurized the melt. Possible and in the majority of cases it is also advantageous to have a gas cushion in the head of the To leave shaping zone. This creates an additional soft pressure compensation created and a possible with rapid adjustment of the polymerization process Polymerization in the supply lines avoided, the section (10) located, first introduced melt ze solidifies as a result of polymerization also first during in section (9) even higher viscosity and in section (8) low viscosity melt is present The pump pressure pushes the plug towards the end of the pipe, whereby by friction or by the counter pressure generated by the trigger device Pump pressure is almost compensated. If the polymer located in section (10) has achieved sufficient strength, is immediately peeled off via the device (5), while at the top of the shaping zone via the mixing device stä @@@ g catalysed melt is supplied, if necessary, can also be done beforehand an active pull can be exerted on all plugs by means of the Abz @@ s device (5), in order not to let the pressure in the shaping zone become too great. By ent @@ computing The inlet and outlet speed is then regulated in the dosing device a quasi-steady state.

Lactams which can be used in the context of the invention are the known ones Polyamide-forming lactams, such as in particular those with six or more carbon atoms in the lactam ring, including the C substituted lactams. These include, for example Lactams that are not from caproic acid, oenanthic acid, caprylic acid. Pelargonous acid Derive capric acid, etc., preferably the known and most commonly used lactam of this series the @caproic acid lactam, also known as caprolactam for short.

According to the invention, all known caalyzers and activators can be used Can be used for alka @@sche rapid polymerization.

These include, for example, alkali or lactams; these are Er @ alkali compounds B you. z Reaction prod @ kie 4 from Lactamed and sodium or potassium or the reaction products from lactams and hydroxides, oxides, hydrides and carb @ nates of the metals mentioned in addition to acid derivatives as activators Actuators include, for example, acid halides the chlorides the esters, anhydrides, mit @ iles, amides and the like a combination of Be Accelerated is composed, for example, of the reaction product of potassium hydroxide with caprolactam and benzoyl chloride together. Further catalyst / activator combinations exist from the alkali or alkaline earth metals or their hydrides, olyden1 hydroxides, carbonates and nitrogen compounds with at least one tertiary nitrogen atom, where as a substance compound e.g. N @ acyl-lactams, N-substituted cyclic @ Imide a dicarboxylic acid can be used specifically e.g. N-acetyl-t-caprolactam, N-Actyl-N äthyl @ p-toluene sulfonamide, N-Nitroso 2 pyrrolidone and others another class Activators containing precursors with a tertiary nitrogen atom include urea and thiourea derivatives such as diphenylthiourea, N-phenyl-N'-butyl urea, Triphenylguanidine, also isocyanates such as 2-4 toluene diisocyanate, bis (Capryllactam - N - carbamido) - 1,6 - hexane, the anilide of pyrrolidone N N -carboxylic acid and many others.

As already mentioned, the lactam armlet heats up during the polymerization and when using caprolactam to temperatures in the order of magnitude of about 1800 in contrast cum metal strand casting, in which the metal melt as a result Cooling solidifies. Here, the solidification of the melt by increasing the temperature accelerated and it was even necessary to have a certain temperature in the course of the process the polymerization is achieved. For this reason the shaping @ zone is good isolated. Especially when starting up the system, energy is supplied in the cheapest Sections of the device (10 and 9) the polymerization process in the lactamachmelse influenced: By applying a rising temperature gradient in the conveying direction an increase in the rate of polymerization is achieved without. that the temperature the starting melt increases and thus impairs their handling and stability Must be depending on the profile. design of the withdrawal speed and the temperature of the starting melt forms an equilibrium state, in which - assuming sufficient insulation of the shaping device - none or only very little energy has to be supplied.

Heating with steam, for example, is suitable for such an energy supply or by means of electrical resistance pick-up body, these heating elements in different different heatable sections (8), (9) and (10) of the shaping device attached soin can. Because of the poor thermal conductivity of the lactam melt However, inductive heating or high frequency heating is preferred0 These offer the advantage of an even, controllable energy supply over the whole cross-section in relatively precisely definable sections. This gives the possibility to keep the temperature of the outgoing melts relatively low.

The speed of movement of the polymerizing or polymerized Material through the shaping device is made by acting on the melt Pump pressure and the resulting - possibly also with the support of the trigger device - Forced movement controlled in the conveying direction depending on the by the factors described above, such as the amount and type of catalysts and activators, Type of lactam temperature of the melt and temperature control, adjustable polymerization rate The pull-off device (5) at the end of the shaping device brings the eventual required counter pressure and takes over the further transport of the profile As with All polymerisation processes are also one with the polymerisation of lactams Increase in the specific Ge weight associated. The corresponding reduction in volume without taking into account thermal expansion - is about 12% of which occurs the largest Part of discontinuous processes by recharging the increasingly viscous melt in the vertical direction in appearance The shrinkage in the horizontal direction is then only about 1.5 - 2% This loss becomes whole or sum for the most part in the present process from that used in the polymerization Any heating that occurs compensates for thermal expansion. Since the polymerizing Melt in the gel-like state course before solidification easily deformable ietp In addition, according to the method according to the invention, a deformation is caused by the pump pressure of the gel-like, polymerizing lactams, which also creates a good Filling of the Forigebungesone achieved and thus the horizontal shrinkage on The cost of the vertical is further reduced, thus the emergence of a Annular gap between the wall and the solid polyamide avoided, so that the still thin Schmelse escapes into the lower part of the pipe, the application of Pressure also has the advantage that the formation of voids in the polymerizing Material is prevented0 Because after working with higher melting temperatures A certain solidification of the polyamide, however, still a slight horizontal shrinkage Direction, it can occur when creating profile rope @@ with large Cross-sectional area may be necessary, the formation of a ring gap in addition by continuously reducing the cross section in section (9) of the shaping device to prevent There is also the possibility of expediently arranged, yielding annular sealing collars attached to a suitable 0 to be determined experimentally Place of the shaping device are attached, the formation of such To prevent annular gap in this case, if necessary, af a specified Reduction of the cross-section of the pipe can be dispensed with0 It is advantageous as a material For such sealing rings, heat-resistant plastics with a low tendency to stick and a low coefficient of friction, such as @@ tetrafluoroethylene Depending on the working conditions, a continuous one can of course also be used Enlargement of the clear cross-section of the shaping device may be expedient, to compensate for an increase in volume at higher temperatures. Advantageously the shaping tube is polished on the inside with the mixing head and known release agent provided to a clean detachment of the polymeric To ensure melting and smooth sliding. A perfect separation effect is at this continuous process of particular importance, to blockages in the continuous course of the process, the formation of imperfections and cavities in the polymer to be avoided with release agents in continuous operation is not possible, they become firmly adhering Coatings made of e.g. polytetrafluoroethylene or silicone stoving enamels in the shaping zone preferred. The separating effect can be achieved by adding suitable, per se known Lubricants for Lactamohmelze can be improved, whereby under certain circumstances the very expensive coatings can be omitted.

As already mentioned above, the heating devices provided can Its so divided into different sections along the shaping device that a temperature control adapted to the respective requirements over the length The number and arrangement of the calibration tube is not critical either Cooling possibilities can be provided in this part of the device The shaping zone itself only needs to be long enough to allow the polymer to be left behind the pipe has sufficient inherent strength to be taken over by the trigger device An additional tempering of the product can be done depending on the needs still in the shaping zone or directly after the same in front of the take-off device be switched on as expedient and economically favorable or the deduction then conveys the material through a corresponding one, as shown in the illustration Oven. Combinations of such devices are of course possible, as well also the cutting of the profile parts after the suction and annealing of the semi-finished product in cut to length.

The nature of the process described above allows it to be continuous Manufacture of semi-finished products from rapidly polymerizing Iaotam melts, their cross-section largely varied can be, however, preferably circular, rectangular or other regular shape. Following the shaping other post-treatments such as smoothing the surfaces, embossing, stretching or the like. Be connected in continuous operation.

There is still a certain amount of material obtained by this process Residual monomer content, which depends on the polymerization temperature, the residence time in the plant and the duration and level of tempering fluctuates. By prolonged tempering it can be largely reduced, but there is often also one that acts as a plasticizer higher residual monomer content is absolutely desirable.

In this pallet, the degree of conversion can also be determined by adjusting the polymerization system be influenced.

E @ reads in the context of this invention, constructive modifications of the Make device according to the respective requirements. That's the way it is E.g. possible, the procedure in horizontal, ascending or descending work trip to execute. Preferably one will use gravity and the vertical one Prefer to lead the work @ run.

Claims (1)

P A T E N T A N S P R Ü C H E @) Process for producing profiled polyamide moldings, such as rods, strips, tubes, moldings of any profile and the like by way of an alkaline rapid polymerization of lactams with 6 or more ale 6 carbon atoms in the lactam ring, characterized in that there are two heated agitator vessels one or more lactams melts, one of which Then melt the satellite, the other contains the activator, these stable ones Melts that do not polymerize or polymerize slowly under the given conditions by metering devices in the concentration of the activator and catalyst continuously combined and mixed in the melt-dependent ratios, these The combined melt is fed continuously to a shaping device, whereby the polymerization at a temperature above the melting point of the lactam, but is below the melting point of the polyamide being formed, begin and then in the shaping device at by the exothermic reaction and optionally rising through active heating, but always below the enamel. point of The polyamide formed allows the permanent temperatures to subside and the solid formed The profile piece is continuously withdrawn from the shaping zone. 2.) Device for performing the method according to claim 1, characterized in that one below the other, one above the other or one behind the other two Heated and closed melting devices (1) connected in parallel, each with feed device, agitator and protective gas feed line to each melting device connected a metering device (2), then a common mixing device (3), subsequent Pormgebungsvorrichtung (4) with shaping zone, Abzugerchr, associated Tempraturregeleinrichtungem, Schutagae-Zn (11) and discharge (12) valves, furthermore following an extraction device (5), a post-heat treatment (6). and finally a cutting or trimming device (7) are arranged0 3e) device according to claim 2, characterized in that the shaping device (4) closes ) divided into several independently thermostatically controlled sections (8,9,10) and has a gas (11) and a degassing valve (12). 4e) Device according to claims 2 and 3, characterized in that that infinitely variable gear pumps are used as the metering device 5.) Device according to claims 2 to 4, characterized in that the light Cross section of the shaping device (4) i in the direction of flow of the polymerizing Masses seen, steadily decreased or increased within the polymerization zone iath 6 ..) Device according to claims 2 to 5, characterized. that in of the shaping device (4) one or more annular sealing collars are attached, which are preferably made of a plastic based on Tetranac. räthylen exist. 7.) Device according to claims 2 to 6, characterized in that that the shaping device (4) and the mixing device (3) are polished inside and optionally itt a separating layer preferably made of a plastic the base of tetrafluoroethylene are provided.