DE1959464A1 - Method and device for the continuous extrusion of endless profiles with a jacket made of thermoplastic material and a foam core and profiles produced according to this - Google Patents

Description

FARBENFABRIKEN BAYER AG

LEVERKU S EN-Beyerweik Patent department

2 6th NOV. 1969

Method and device for the continuous extrusion of endless profiles with a shell made of thermoplastic plastic and a foam core and profiles produced by this method

The present invention is directed to a method and a device for the continuous extrusion of endless profiles of any cross-section with a jacket thermoplastic plastic and a foam core and on the profile itself, taking for the manufacture of the jacket an extruder with a compression nozzle is used, and the foamable reaction mixture through a central tube in is introduced into the cavity of the shell formed. The jacket is then placed in a downstream calibration device held in the desired shape until the foamable mixture has reacted.

There is already a device of this type known in which the foamable mixture at the same time as the exit deB consisting of a thermoplastic jacket from the press nozzle by means of a second, centrally located nozzle in the

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formed tube is introduced. That way Manufactured profiles have the disadvantage that straight the edge zone of the core, i.e. near the shell, the foam core has a lower density than in the middle itself. Accordingly, the profile formed has strength properties across its cross-section, in particular in the With regard to the flexural strength, which are exactly the opposite of the desired strength properties. . Because the flexural strength of a profile can be increased very significantly by a reinforced edge zone, while a "reinforcement practically no improvement in the strength values of the middle of the body.

It has now surprisingly been found that a profile can be produced whose foam core, viewed in cross section, has a density that "drops from the edge zone of this core to its center According to the present invention, this is achieved in that the liquid reaction mixture is only introduced into the cavity formed by the extruded jacket at that point at which the temperature of the jacket is already has dropped to at least 100 ⁰ O. The temperature of the jacket at the point of entry of the reaction mixture should preferably be between 20 ⁰ G and 50 ⁰ C. This ensures that premature foaming of the liquid, foamable reaction mixture as a result of the action of the temperature of the Mantle is avoided.

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To what extent the point of introduction of the foamable mixture from the press nozzle for the production of the jacket must be removed depends on a great many factors. First of all, this is a question of the thermoplastic material of the coat. For example, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, Use polystyrene, polycarbonate and polyamide. The extrusion speed and the exit temperature from the strand] -: esse are further factors, as well as the cooling effect achieved in the calibration device. on the other hand is as further. The flow rate of the reaction mixture itself increases regard. Chemical starting components, especially those based on polyurethane, but also unsaturated ones, are suitable for this Polyester, epoxy resin, f-oaprolactam and their copolymers. As a further factor for the special choice of the upper temperature limit of the jacket at the moment of installation of the reaction mixture are the properties of the one used Propellant to be considered.

It is relatively easy to empirically determine the suitable upper temperature limit for each individual case through experiments by changing the distance between the press nozzle and the mixture feed nozzle and cutting open the profile produced and compare the cross-sectional image.

According to a particular embodiment of the invention In the process, the foaming chamber is sealed on all sides, the particular purpose of which is to ensure that the foamable, liquid mixture cannot flow back into the hotter area in the cavity formed by the jacket.

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The device for carrying out the method is based on an extruder with a compression nozzle for the formation of the jacket and a central nozzle for the foamable reaction mixture as well as a downstream, cooled calibration device. What is new and inventive can be seen in the fact that a mixture feed pipe protrudes from the extrusion head of the extruder into the cavity of the calibration device, the nozzle of which is in the area in which the temperature of the jacket has already dropped ^{to at least 100 ° C.} It does not matter whether the cavity in the jacket is achieved by a pressure acting therein, for example by means of compressed air or by suction air applied from the outside. If necessary, the feed pipe can also be designed as a shaping core, so that its outer diameter corresponds to the inner diameter of the jacket.

According to an advantageous development of the invention Device, the mixture feed pipe is mounted to be longitudinally displaceable. This has the particular advantage that the entry point for the reaction mixture corresponds to the properties the materials used, the extrusion speed and the cooling effect can be optimally adapted.

According to a further, special embodiment is on that Mixture feed pipe arranged behind the nozzle a seal which rests against the inner surface of the jacket. A This prevents the reaction mixture from flowing back behind the nozzle.

The profile according to the invention, which according to the invention Method is produced is characterized in that the density of the foam core viewed in cross section from

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its edge zone decreases towards its center, for example approximately within the limits of 1.2 g / cm to 0.3 g / cm.

example 1

A hose with a diameter of 50 mm and a wall thickness of 1 mm is extruded from standard polystyrene by means of a conventional extruder and a so-called cable nozzle (press nozzle). The exit speed is 1 m / min. The outlet temperature of the tube is 19O ⁰ C. Thanks to the intensive cooling is the hose Tempera door at a distance of 500 mm sunk behind the molding die 75 ⁰ O. At a distance of 500 mm behind the press nozzle, a polyurethane reaction mixture is continuously introduced through a wide nozzle in an amount of 1000 g / min. The polyurethane reaction mixture has the following structure:

Component A

75 parts by weight of polyether made from ammonia and propylene oxide,

OH number 590
20 "" polyether made from trimethylolpropane and hexanetriol,

reacted with propylene oxide and ethylene oxide,

OH number 37

5 »" 1,4 butanediol
7.5 "" Trichloromonofluoromethane 1.5 "" Permethylated diethylehtriamine 1.0 "" Polysiloxane-polyalkylene-glycol ether-copoly-

merisat

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BAD ORIGINAL

1 0 9 ^ 2: 3/1 9 7 _:

Component B

122 parts by weight of carbodiimide-modified diphenylmethane

4,4'diisocyanate (NCO content 31 #).

The length of the calibration section is 4.5 m. The cross-section of a plastic profile produced in this way has a massive edge zone of the polyurethane plastic of 1.6 mm with a density of 1.2 g / cm- ⁵ .

Example 2

A box section measuring 200 mm 25 mm with a wall thickness of 1.5 mm is extruded from low-pressure polyethylene with the aid of a cross-injection P head and a commercially available extruder. The exit speed at the press nozzle is 1 m / min. The exit temperature at the extrusion orifice is 175 ⁰ C. At a distance of 75.0 mm behind the molding die is the temperature of the Polyäthylenprofils decreased to 70 ⁰ C. At a distance of 750 mm behind the press nozzle, a reaction mixture is continuously introduced through a second nozzle in quantities of 2.5 kg / min.

The reaction mixture has the following composition:

^ Component A

• 150 parts by weight of an unsaturated polyester resin

3 "" of a Fa salt of sulfurized castoroleic acid in 50% aqueous solution 2.5 "" bis (dimethylethylamino) methylamine 1 "" dimethylpolysiloxane

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Component B

4.5 parts by weight of methyl ethyl ketone ■

Component 0

30 parts by weight of a crude 4,4 ^f -diphenylmethane diisocyanate.

The length of the calibration section is 5.5 m. The cross-section of the profile produced in this way has a massive edge zone of 1.7 mm with a density of 1.1 g / cm, which in the core has a value of 0.37 g / cm ⁵ decreases.

Example 3

Instead of the polystyrene jacket according to Example 1 or the polyethylene casing according to Example 2, a jacket made of ABS polymer with a wall thickness of 1 mm is produced. The nozzle outlet temperature of 180 ⁰ C. Analogously to Example 1 is 500 mm behind the molding die, the tube temperature 75 ⁰ C. Further processing takes place as in Examples 1 and 2. FIG.

Example 4

A sheath made of polyamide is extruded. The nozzle outlet temperature of 230 ⁰ C. The cooling section is 900 mm long. The wall thickness of the jacket is 1.5 mm. The temperature at the nozzle for filling of the reaction mixture at 85 ⁰ O. Further processing is analogous to Example. 1

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The method according to the invention is now based on a drawing, the device according to the invention as well as that according to the invention Profile shown in exemplary embodiments or explained in more detail, namely show:

Figure 1: The side view of the device purely schematically in section

FIG. 2: a cross section through the profile produced, and

Figure 3: the density distribution of the profile according to Figure 2.

In FIG. 1, a thermoplastic material is melted in an extruder 1 (indicated) and extruded through the press nozzle 2. The educated. The jacket 3 is immediately introduced into a calibration device 4 which is provided with a cooling jacket 5 and also has a suction chamber 6 which brings the jacket 3 to bear by the suction effect, so that the jacket 3 encloses a cavity 8 within the calibration device 4. The reactive mixture is stored in a cooling chamber 9, from which a mixture feed pipe 10 protrudes into the calibration device and which is set such that its nozzle opens into that area of the calibration device in which the temperature of the jacket 3 has already dropped ^{to at least 100 ° C} , preferably to the temperature that

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is to be regarded as optimal according to the influencing factors. To the device for the use of different materials To make adaptable, the mixture feed pipe is mounted so that it can be displaced longitudinally, so that the mixture nozzle 11 in their distance from the press nozzle 2 is adjustable. A sealing ring 12 serves to seal the cavity 8 and at the same time the guide of the longitudinally displaceable mixture feed pipe 10. Shortly behind the nozzle 11 is the mixture feed pipe 10 surrounded by a sealing ring 13, the circumferential surface of which rests against the inner surface of the jacket 3 and the Prevents the reaction mixture 14 introduced into the jacket from flowing back into the hotter area of the jacket 3. The reaction mixture 14 then foams up to form the foam core 15.

In Figure 2 shows the cross section of the manufactured profile the jacket 3 made of a thermoplastic material as well the foam core 15, which in its edge zone 16, i. immediately below the jacket 3, has a significantly greater density than in its center 17. In the edge zone (FIG. 3) the density is, for example, 1.2 g / cm, in the center of the core 17, for example, 0.4 g / cm.

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Claims (7)

Claims; A method for continuous extrusion of endless profiles, with a jacket of thermoplastic material and a Schäumst off core, wherein a cover sheet extrü- ² diert 'and according to the desired outer contour "held ^r and is introduced into the formed cavity a foamable, liquid reaction mixture, characterized marked- * indicates that the reaction mixture only takes place at that point is introduced into the cavity at which the temperature of the Mantle has already dropped to at least .100 ⁰ G. '' ^Λ ι - - ■■ - - - ■ ^: · - ■■■■ -. · ■■■ 2. The method according to claim 1, characterized in that the temperature of the jacket is between 20 ⁰ C and 50 ⁰ O at the point of entry of the reaction mixture. 3. The method according to claim 1 and 2, characterized in that that the foaming chamber is sealed on all sides. 4. Apparatus for performing the method according to claims 1 to 4, consisting of an extruder with a compression nozzle for the formation of the jacket and a central nozzle for the foamable reaction mixture and from one downstream, encased calibration device, thereby w characterized that from the extrusion head of the extrusion press (1) a grit feed pipe (10) protrudes into the cavity (8) of the calibration device (4), the nozzle (11) of which is in the area in which the temperature of the jacket (3) is already has dropped to at least 100 ^{° C.} Ie A 12 622 - 10 - 109823/197 1 5. Apparatus according to claim 4, characterized in that that the mixture feed pipe (10) is mounted so as to be longitudinally displaceable. 6. Apparatus according to claim 4 and 5, characterized in that that on the mixture feed pipe (10) behind the nozzle (11) a seal (13) is arranged, which against the inner surface of the jacket (3) is applied. 7. Profile with a jacket made of thermoplastic material and a foam core, which is produced according to the method according to Claims 1 to 3 is made, characterized in that the density of the foam core, seen in cross section, decreases from its edge to its center. Le A 12 622 - 11 - 109823/1971 Blank page ft