DE2445566A1 - METHOD AND EQUIPMENT FOR TREATMENT OF THE OUTER AND INNER SURFACE OF AN EXTRUDED PIPE MADE OF THERMOPLASTIC, RESINY MATERIAL - Google Patents

Description

PATENT ADVOCATES A. GRÜNECKER

dipl.-inö.

H. KINKELDEY 24 k 5566 w. "STOCKMAlR

DR.-INQ. AaE (CALTECH)

K. SCHUMANN

'" DR. RER. NAT. · DIIW -.- PHYS.

P. H, JAKOB

DIPL.-INQ.

G. BEZOLD

DR. RER. NAT. · 0IPL ₁ -CHEM.

MUNICH

E. K. WEIL

DR. RER. OEC. INTO THE.

LINDAU

8 MUNICH 22

MAXIMILIANSTRASSE 43

Sept. 24 P 8564-sh

MITSUI PETROCHEMICAL INDUSTRIES, LTD.

No. 2-5, Kasunigaseki 3-Chome, Chiyoda-Ku, Tokyo, Japan

Method and device for treating the external and inner surface of an extruded pipe made of thermoplastic, resinous material

The invention relates to a method and a device for Treatment of the outer and inner surfaces of an extruded thermoplastic resinous pipe Material. The method according to the invention and the device according to the invention are intended to improve the gloss on the surface of the pipe and additionally the. Increase the stability of the shape of the pipe. The. Invention relates

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also a method and apparatus for smoothing the inner surface of a tube made of a thermoplastic, resin-like material, which is produced by extrusion is generated from the extruder.

Pipes made of thermoplastic, resin-like material are usually produced by extrusion. at This process uses a tube of thermoplastic, resinous material that is extruded in a molten state is passed through a calibration nozzle or mold into a calibration so that it is calibrated. The sheen on the surface of such a pipe may vary depending on the temperature of the pipe at which it passes through the Calibration nozzle is running, may be different. Ordinary thermoplastic resinous material is the temperature that gives the highest values of the physical properties, different from the temperature, at which its surface gloss is strongest. As a rule, the physical condition is more important to improve. Therefore it has been customary to use the temperature at the expense of the surface gloss, which gives the highest values of physical properties.

Lose pipes made of thermoplastic, resin-like material their surface gloss due to the influence of temperature. This disadvantage of pipes made of thermoplastic, Resinous material is attributed to the intermittent movement of the pipes, commonly called sticking and Sliding is described and is caused by the fact that an under pressure method or internal pressure method is used the pipes are wading through the calibration nozzle. Extruded by means of an extruder Pipes made of thermoplastic, resin-like material are

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used to make a wide variety of finished products such as bottles and other hollow articles made by blow molding from the thermoplastic resinous tubes will. Conventional method of making transparent bottles using a tube a thermoplastic, resinous material such as polypropylene, and biaxial Expanding the same have the disadvantage that they are not able to produce transparent bottles because turbidity occurs in the bottles produced. Investigations carried out to avoid this disadvantage have shown that the cloudiness in the bottle body at the. Roughness of the inner surface of the bottle lies and that the surface roughness is on the inner surface of the pipe, which is an intermediate product is produced by extrusion. In particular, the refraction and irregular reflection of light are through very small irregularities on the inner surface of the object are responsible for the opacity. It is possible, the outer surface of the intermediate product or finished product by means of mechanical Smooth facilities. In the case of blow molded hollow articles, this is mechanical However, smoothing the inner surface of the intermediate product or the finished product on difficulties.

The invention is based on the object of a method and a device for treating the outer surface of a to create extruded pipe that enables ee, to produce a tube with a high surface gloss by placing the extruded tube and the inner wall of the calibration

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a lubricant is supplied to the nozzle.

This task is related to the method of treatment the outer surface of an extruded pipe made of thermoplastic, resinous material, that by extruding molten resin from an extruder and calibrating it with a calibrating nozzle is produced, solved in that a lubricant a front end portion of the calibration nozzle is fed along the front end portion which is arranged at a distance from the extruder is.

Regarding an apparatus for treating the outer surface of an extruded pipe made of thermoplastic, Resin-like material, the object is achieved by a calibration nozzle or form for calibrating the pipe, the for extrusion molding of a thermoplastic resin in a pipe shape is extruded from an extruder, and a lubricant feed device, which is attached to a front End portion of the calibration nozzle, which is opposite the extruder at a distance, is arranged and to it serves to supply a lubricant along the front end portion of the calibration nozzle.

According to one aspect of the invention there is means for supplying a lubricant to the tube at the front end the calibration nozzle on the side of the extruder. The lubricant used can be selected from one group can be selected which comprises a surfactant, wax, silicone oil and soapy water. A surface active one Means is particularly preferred because when the pipe is cooled from the pipe by means of a coolant, for example water, which is separated

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is in the cooling tank that he follows the calibration. The inventive device for supplying a Lubricant to the pipe, which is arranged in the calibration nozzle, is at a distance from the extruder. Therefore, it is not necessary to use a heat resistant lubricant as a section of the extruder extruded and lubricated tube a somewhat diminished Temperature.

One of the excellent merlanals of the invention is made in that the device for supplying a lubricant is provided at the front end portion of the calibration nozzle, as already mentioned. Because of this With this feature, it is not necessary to limit the lubricant used to one that is heat-resistant is. Furthermore, the lubricant supply device comprises a recess formed at the front end of the calibration nozzle. This feature leads to that the lubricant is fed to the pipe as a continuous stream with a constant flow rate, since the Lubricant is stored in the recess, even when the supply of the lubricant through the lubricant supply line irregularly and takes place with interruptions.

The invention eliminates the need for an additional Mount the lubricant supply device between the extruder and the calibration nozzle so that it is possible to compact overall dimensions for a device for manufacturing an extruded tube made of thermoplastic resin. . · "

According to the invention, the volume of a pipe is supplied Lubricant determined by the speed,

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with which the pipe is manufactured, so that the volume of the supplied lubricant remains constant Has value and the lubricant can be supplied in suitable quantities.

Another advantage offered by the device according to the invention for supplying a lubricant, consists in that annular grooves are provided inside the opening of the calibration nozzle. this makes possible to apply a lubricant uniformly to all sections of the outer circumference of the pipe, so that a loss of gloss and gloss irregularities caused by the calibration could be kept as small as possible.

Another object of the invention is to provide a method and apparatus for smoothing the internal Surface of an extruded pipe made of a thermoplastic resin without the use of mechanical Means whereby transparent, hollow objects can thereby be made from the tube.

This task is in terms of a method for Treatment of the inner surface of a pipe made of thermoplastic, resinous material that passes through Extrusion is generated from a tubular nozzle, which is provided with a torpedo in the central section of the nozzle is solved in that inert gas is fed into the interior of the tube so that the inner surface of the Pipe is smoothed. The object is in terms of a device for treating the inner surface of a thermoplastic, resinous material that is extruded from a tubular nozzle with a torpedo in it central section is made, solved by a

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Inert gas source, a valve connected to the inert gas source, one formed in the central portion of the torpedo Channel for inert gas and a feed line for the inert gas, which connects the channel with the valve.

According to this aspect of the invention is a device provided, which is used in · 'the bore of a tube extruded from the extruder made of thermoplastic To feed resin an inert gas, for example nitrogen gas, carbon dioxide, helium gas or the like .. A channel for the inert gas is formed in the mandrel and torpedo of the extruder and is in communication with the supply source held for the inert gas.

It is not clear why the injection of an inert gas into the bore of the thermoplastic resin pipe smooths its inner surface. It is assumed, however, that one factor that has to do with smoothing the inner surface is that a Oxidation of the resin, which is extruded in the liquid state at elevated temperature, by its presence of the inert gas is prevented and the occurrence of irregularities on the inner surface is excluded.

The invention enables a pipe made of thermoplastic Manufacture resin with a smooth inner surface when shaping the 'pipe and making one hollow object can be continuously carried out by blow molding from the tube. This feature of the invention gives the advantage of continuous production as a secondary effect. If conventional manufacturing ~ procedure is applied is the inner surface of the

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Thermoplastic resin pipe is very rough, so that it is impossible to pinch a to create perfect seal so that the air blown into the tube for blow molding is under high pressure tends to flow back to the extruder. This has often resulted in the tube near the nozzle tears at the front end of the extruder. The inner surface of a pipe made of thermoplastic resin that is produced according to the method of the invention, can be completely sealed, so that the aforementioned Disadvantage of conventional methods can be eliminated.

This invention is of particular use when the thermoplastic, resinous material is a highly crystalline, is a solid polymer of mono-α-olefins having up to six carbon atoms, for example ethylene polymers high density, isotactic polypropylene, poly-4-methyl-1-pentene, polybutene-1 or the like.

Embodiments of the invention are in the drawings and are explained in more detail below. Show it:

Fig. 1 is a flow chart showing the manufacturing steps for finished products;

Fig. 2 is a section through a calibration nozzle with a device according to the invention for Treatment of the outer surface of a pipe is provided in conjunction with the Extruder and a pipe;

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3 shows a view of the calibration nozzle shown in FIG. 2 from the left;

4 shows a section through a tubular nozzle which is equipped with a device according to the invention for Treatment of the inner surface of a pipe is provided;

5 shows a section similar to FIG. 4, but showing a further embodiment of the invention shows;

Fig. 6 (a) is a graph showing the roughness curve shows the inner surface of a bottle made by blow molding from a tube made according to the invention Procedure was manufactured;

Fig. 6 (b) is a graph showing the roughness curve of the inner surface of a Shows a bottle that has been blow molded from a tube that, after a conventional process ;.

Fig. 7 (a) is a microscopic photograph of the inner surface of a pipe made in accordance with the present invention Procedure was established; and

Fig. 7 (b) is a microscopic photograph of the inner surface of a pipe that is after a conventional method ".

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Reference is first made to FIG. 1. An extruder is used to extrude a pipe 10 made of polypropylene 11 used · The tube 10 is led through a calibrator 12 to a cooling tank 13, where it is below the crystallization temperature is cooled. If the tube 10 is made of polypropylene, crystallization can thereby occur be accelerated so that the pipe is heated to approximately below 120 ° C. A suitable one, not shown Drive device is used to drive the tube 10 from Extruder 11 to the calibrator 12 and the cooling tank 13 to move.

After the tube has been heated 10 in a heating furnace 14 again to a temperature which is slightly lower than its crystalline melting point (about 140 ⁰ C to 167 ⁰ C in the case of a tube of polypropylene), it is represented by a drawn hopper 17 a pair Molded parts 15 and 16 supplied. The mold parts 15 and 16 alternately grip the tube 10 and move it away from the heating furnace 14 through the pulling funnel 17 in order to align the tube 10. The molded part 15 engages the tube 10 and moves it away from the heating furnace 14 in order to stretch and align the tube 10. While the tube 10 is being pulled from the molding 15, the other molding 16 remains in the open position and moves towards the heating furnace 14 and stops in a position adjacent the elongated tube where it closes around and engages the tube 10 and is removed from the heating furnace 14 moved away so that a new section of the tube exiting the heating furnace 14 is stretched.

After the molding 16 has closed and as it moves away from the heating furnace 14, it opens the molded part 15, which previously detected the pipe 10 and in a

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Had moved in the direction in which it was from the warming furnace 14 moved away so that a bottle 18 is released, which is produced in the molded part 15 from the tube 10 has been. Thereafter, the molded part 15 moves to the heating furnace 14 and repeats the cycle described. The mold parts 15 and 16 are each connected to a pressure source, the mold parts 15 and 16 pressure feeds so that the tube 10 is expanded so that the bottle 18 is formed. · The thus formed Bottle 18 is moved to a finishing station where it is separated from the other bottles, press scraps removed, the neck of the bottle deburred and drilled to final size.

The invention relates to the treatment of the inner surface of the tube 10 while the tube 10 is being extruded by the extruder 11 and the outer surface of the pipe 10 while the pipe 10 is passed through the calibrator 12.

Reference is made to FIGS. 2 and 3 below. The extruded from the extruder 11 pipe 10 is from a Calibration mold or nozzle 20 calibrated, which via a vacuum line 21 with a vacuum source, not shown is connected so that calibration can be performed smoothly. The said construction is known.

According to the invention is a pipe lubrication device on the front End portion 29 of the calibration form 20 is provided, which is opposite the extruder 11 at a distance. The pipe lubrication device comprises a lubricant supply device, which has a supply opening 23 for lubricant, which is at the front End portion 29 of the calibration mold 20 is formed

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and in connection with a supply line 22 for lubricant is held, a recess 24 formed in the vicinity of the supply port 23 for lubricant is; a groove 26 extending downward from the bottom of the recess 24 to a calibration opening 25, and annular grooves 27 formed in the calibration opening 25 and somewhat within the end face thereof are arranged.

Lubricant supplied via the lubricant supply line 22 moves through the lubricant supply opening Although part of the lubricant is stored in the recess 24, the greater part of it passes through the groove 26 and reaches the calibration opening 25. The lubricant supplied in this way adheres to the outer surface of the tube 10 as it is extruded from the extruder 11 and into the calibration opening 25 is introduced. The lubricant is now in the ring-shaped Grooves 27 introduced, making it up as a thin film of uniform thickness on the outer surface of the tube 10 is distributed. This prevents the outer surface of the tube 10 from having a rough structure obtained when the tube 10 passes through the calibration nozzle 20. Test results show that the surface gloss a pipe produced according to the method according to the invention is twice or three times higher than that of one Pipe that has been manufactured by a conventional method.

In the illustrated and described embodiment two annular grooves 27 are formed in the calibration opening. With this arrangement, the lubricant can the outer surface of the tube 10 can be distributed as a thin film of uniform thickness. It goes without saying, however,

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that the invention does not apply to this number of annular Grooves is limited and that the annular grooves depending on the strength of the lubricant or accordingly other influencing variables can be provided in a suitable number.

In the following an apparatus will be described with reference to Fig. 4, which comprises an embodiment of the invention. An outer nozzle 30 is mounted in a nozzle carrier 31 so that its position in the radial direction on a Adjusting element 32 can be adjusted. Inside the nozzle 30 is an annular resin channel 34 for extruded, resinous material formed. An inner mandrel 36 is carried by a rotary holder 35, which is in the central portion of the channel 34 is arranged and at the rear end of a torpedo 37 is mounted. Molten resin coming from the extruder, not shown is extruded, is introduced through an inlet port 38 in the nozzle 30, passes through the annular resin channel 34, which is limited or formed by the nozzle carrier 31, the nozzle 30, the mandrel 36 and the torpedo 37, and is discharged from the nozzle 30 through an outlet port 39. When the resin leaves the nozzle 30, it has the Shape of a tube. The construction described is known.

According to the invention a device is provided that this serves to supply inert gas to the interior I of the tube 10 so that the inner surface S thereof becomes smooth. As shown is, a passage 40 for the inert gas is formed in the central portion of the torpedo 37 and through a valve 42 connected to an inert gas source 41 mounted outside. The inert gas flowing through valve 42 goes through a pipe .43 into an inlet port 44 which is in the

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Nozzle carrier 31 is formed from where the inert gas through a channel section 40a in the nozzle carrier 31, a Channel section 40b in rotary holder 35, a channel section 40c in mandrel 46 and a channel section 40d in the torpedo 37 flows into the interior I of the tube 10. It understands that the invention is not limited to this arrangement of the channel sections 40a to 4Qd and that the Arrangement can be changed as desired. Fig. 5 shows another arrangement of the channel sections.

The embodiment shown in Fig. 5 is essentially similar to that of Fig. 4, and like reference numerals denote like parts. In FIG. 5, the nozzle carrier 31 comprises a first carrier section 31a and a second carrier section 31b, which are connected to one another via bolts 50. The point at which the nozzle is located can be adjusted in the radial direction by means of an adjusting device 32. The torpedo 37 is disposed in the central portion of the resin channel 34 in the outer nozzle 30. The axial position of the nozzle 30 is determined by a bush 31. The mandrel 36, which has a screw section 36a, is fastened to the first support section 31a via bolts 52. A tubular member 55 in which a resin channel 54 is formed is connected to the side of the first support portion 31a. A _u f this way, the molten resin flowing through the channel 54, introduced into the nozzle 30 and is discharged therefrom through the annular channel '34, so that a tube is produced.

In this embodiment is. the gas channel 40 formed in the central portion of the torpedo 37 over a channel section 40d, a central channel section 40c in the mandrel 36 and a channel section 40a on one side

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of the dome 36 connected to a channel 44, which via the pipe 43 and the valve 42 as in the case of the previously described Embodiment is connected to the inert gas source 41. The channel section 40c is at his one end is closed by a plug 56. If so desired, however, the channel portion 40a can be omitted and the plug 56 can be omitted, so that the channel section 40c at its end with the Channel 44 can be connected.

The mode of operation of the embodiment shown in FIG. 5 and the advantages achieved thereby are those of in the embodiment shown in Fig. 4 similar.

An example of the method of the present invention is detailed with reference to the device shown in Fig. 4, which is so adapted that it Can carry out procedures in practice.

In the apparatus shown in Fig. 4, the temperature at the front end of the outer nozzle 30 was set to 240 C and then the valve 42 was set to feed carbon dioxide into the channel 40 at a rate of 5 liters per minute. A polypropylene resin was fed to the extruder 11 at a rate of 40 kg per hour; this was extruded from the extruder into the calibrator 12, producing a tube with an outside diameter of about 30 mm and an inside diameter of about 12 mm at a rate of 1.5 meters per minute. The tube produced in this way was ^{heated again to approximately 155 °} C., stretched in the longitudinal direction to approximately four times its original length, and subjected to a blow molding process by dividing the tube from a.

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metallic form was detected, so that one o. Bottle with a thickness of approximately 0.5 mm and a capacity of 65i
transparent.

like from 650 cm. The bottle was pretty

In a control experiment, instead of carbon dioxide, duct 40 was supplied with air with a throughput of 5 liters each Minute according to the state of the art. In the same way as previously described extruded a tube and blow molding the tube into a bottle. With the manufactured bottle the entire body was cloudy, and there were partially darker and lighter areas.

Some test strips were made from the side wall of each of the two different bottles so that their major axes are axially parallel to one another. The roughness of the inner surface of the sample strips of the bottles was measured using a surface roughness meter; it was a SH-3A universal surface shape testing machine manufactured by Kosaka Institute, Inc., Japan. The results of the tests are shown in Figures 6 (a) and 6 (b). It is found that the irregularities formed on the inner surface of the bottle made by the method of the present invention are only about 2 microns in size, as shown in Fig. 6 (a), whereas those formed on the inner surface of the conventionally made bottle formed irregularities are 8 microns or more in size.

To directly determine the benefit achieved by the invention, the interior surfaces

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a tube made according to the invention and a tube made in a conventional manner photographed and enlarged 30 times. The results are shown in Figs. 7 (a) and 7 (b). It can be seen that - as FIG. 7 (a) shows - the inner surface of the manufactured by the method according to the invention The tube is essentially smooth, whereas the inner surface of the tube is conventionally manufactured Rohres has irregularities of considerable size that are randomly formed therein.

Patent claims:

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Claims (4)

Claims 1, "method of treating the outer surface of a J extruded tube of thermoplastic resinous material by extruding molten resin from an extruder and calibration thereof is prepared by a sizing die, characterized in that a lubricant to a front end portion of the sizing die along the front end portion is fed, which is arranged at a distance from the extruder. 2. Apparatus for treating the outer surface of an extrusion Pipe made of thermoplastic, resin-like material, characterized by a calibration nozzle or mold (20) for calibrating the pipe (10) which is used for extrusion molding of a thermoplastic resin in pipe form has been extruded from an extruder, and a lubricant feeder (22 to 27) attached to a front end section (29) of the calibration nozzle, which opposes the extruder (11) at a distance, is arranged and serves along the front end portion to supply a lubricant to the calibration nozzle. 3. A method of treating the inner surface of a pipe made of thermoplastic, resinous material, the is produced by extrusion from a tubular nozzle provided with a torpedo in the central portion of the nozzle is, characterized in that inert gas is fed into the interior of the tube, so that the inner Surface of the pipe is smoothed. 509815 / 1U0 2U5566 4. Apparatus for treating the inner surface of a thermoplastic, resinous material that is passed through Extruding made from a tubular nozzle with a torpedo in its central section is featured through an inert gas source (41), a valve (42) connected to the inert gas source, an im central section of the torpedo (37) formed channel (40) for inert gas and a feed line (40a / 40b, 40c, 40d, 44, 43) for the inert gas, which connects the channel with the valve. 509815/1140