Underwater pelletizing apparatus and method

Abstract

An underwater pelletizing apparatus includes a die plate assembly having a melt inlet for feeding liquid melt and melt outlets for discharging a plurality of melt strands into an adjacent cutting chamber, a cutting device for producing granulate particles from the melt strands, a cutting chamber that is adjacent to the die plate assembly and can be filled with water or some other liquid, which has at least one inlet for feeding water or other liquid into the cutting chamber, and which has at least one granulate outlet for discharging a mixture of water or other liquid and granulate from the cutting chamber. The underwater pelletizing apparatus also includes where at least one gas inlet, connectable to a gas source, for feeding gas directly or indirectly into the cutting chamber in such a way that fed gas can interact inside the cutting chamber with granulate.

Description

UNDERWATER PELLETIZING APPARATUS AND METHODCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of German Patent Application No. 10 2023 119 050.4 filed on July 19, 2023, which is hereby incorporated by reference in its entirety for all purposes as if fully set forth herein.FIELD OF THE DISCLOSURE

[0002] The disclosure relates to an underwater pelletizing apparatus and to an underwater pelletizing method for producing granulate or pellets from a plastic melt, in particular a polymer melt.

[0003] The disclosure relates, in particular, to a pelletizing apparatus for producing granulate from free-flowing, curable plastic, comprising a die plate assembly having a melt inlet for feeding liquid melt and melt outlets for discharging a plurality of melt strands into an adjacent cutting chamber, a cutting device for producing granulate particles from the melt strands, and a cutting that is adjacent to the die plate assembly and can be filled with water or some other liquid and which has at least one (water) inlet for feeding water or other liquid into the cutting chamber and which has at least one (water / )granulate outlet for discharging a mixture of water or other liquid and granulate from the cutting chamber, and to a method according to the preamble of claim 9. Water is generally the preferred liquid, but other liquids or mixtures of liquids may also be used.BACKGROUND OF THE DISCLOSURE

[0004] Pelletizing apparatuses and methods are known from the prior art, for example from the EP 3 711 923 A1 or EP 3 915 747 A1 applications filed by the present applicant. In such underwater pelletizing apparatuses, a plastic made free-flowing by heating, also referred to as a melt, is fed to a die assembly comprising a die plate that has a plurality of fluid channels. The liquid melt flows through the die plate, which is arranged adjacent to a cutting chamber filled with water. Melt strands flowing out of the holes in the die plate are separated into individual granulate particles or pellets of melt by a blade which is in contact with the die plate and is generally in rotation and aredischarged into the cutting chamber, which is also referred to as a “water box”. The individual particles come into contact with the water in the cutting chamber, thus forming single granules or pellets that solidify over time. Water is fed continuously to the cutting chamber. The pellets are cooled by contact with the water and solidify in the process.

[0005] The pellets thus formed are conveyed out of the cutting chamber by the flow of water in a two-phase flow of water and pellets. In order to expedite the removal of the water / pellets mixture from the cutting chamber, WO2009 / 155196 proposed that air be introduced into a transport pipe downstream from the pelletizing apparatus in order to expedite the conveying of the water and the pellets produced to a centrifugal dryer. After removal, the pellets are separated from the water and dried in a drying process by means of a drying device. The pellets thus produced can later be melted and used to manufacture plastic products, for example in injection molding processes and machines, or in production processes, for example as a liquid adhesive.

[0006] The pellets or granulate particles formed after discharge from the die plate and cutting in the cutting chamber have irregular shapes and more or less elongate, partially curved to rounded or elliptical shapes. The aim in many cases is to approach a spherical shape, as this has advantages with regard to crystallization, flowability and packing density for transport.

[0007] The aim of the present disclosure is to specify a pelletizing apparatus and a pelletizing method for producing pellets or granulate in an underwater pelletizing process to enhance the shape of the pellets in the cutting chamber, in particular in such a way that the pellets produced are nearly spherical in shape.

[0008] The disclosure achieves its aim by means of a pelletizing apparatus according to claim 1 and a method according to claim 9.SUMMARY OF THE DISCLOSURE

[0009] In the pelletizing apparatus according to the disclosure, and analogously in the method, at least one gas inlet connectable to a gas source for introducing gas directly or indirectly into the cutting chamber is provided, such that gas introduced directly or indirectly can interact inside the cutting chamber with granulate. The gas that is introduced directly or indirectly into the cutting chamber in accordance with thedisclosure moves in the water in the cutting chamber and interacts with the initially somewhat free-flowing pellets that are emitted by the die plate assembly and float in the water in the cutting chamber (water box), and which then cool and solidify. After being introduced into the cutting chamber, the gas typically forms gas bubbles that are driven upwards by a buoyant force in the water and are thus set in motion, in addition to the flow of the water introduced into and flowing through the cutting chamber. The gas bubbles can come into contact with the pellets, they can affect the movement of the pellets in the water, can lead to mixing an additional movement of the pellets, and the like. According to the disclosure, the overall result is that, during solidification, the pellets acquire rounder, more uniform and more homogeneous shapes in the cutting chamber than is the case in the prior art. The size and homogeneity of the round or elliptical shape often aimed at for the pellets being formed can also be favorably influenced by the gas that is introduced. According to the disclosure, a better overall quality of the pellets can be achieved in the underwater pelletizing process as a result of the three-phase gas / water / pellet stream or movement in the cutting chamber. According to the disclosure, the gas introduced into the cutting chamber allows pellets or granulate having better properties to be produced; in particular, the gas introduced directly or indirectly into the cutting chamber in accordance with the disclosure allows the pellets produced to approach even more advantageously a compact, in particular spherical shape, or even, ideally, to acquire a spherical shape. Another advantage of the improved approximation of the pellets to a spherical shape in accordance with the disclosure, for example when the polyethylene terephthalate (PET) plastic is used, is that less energy is needed later to liquefy the pellets, because the subsequent crystallization behavior of the pellets is improved. By approaching a spherical shape, the pellets or granules produced acquire a higher internal heat and hence a higher degree of crystallinity or a higher crystallinity or a higher degree of crystallinity, which provides advantages when further processing the pellets in plastics processing systems, and here in particular during melting. Due to the introduced gas, the process can also be carried out better outside what are otherwise optimal operating modes, andit also possible to reduce the wear between the blade and the die plate, or blockages of the nozzle orifices in the die plate.

[0010] The gas is preferably air, but other gases or gas mixtures can also be used. The air is preferably supplied from a compressed gas source. Another factor affecting the solidification process of the plastic is thus provided in the form of the gas that is introduced and the gas bubbles that typically result. The amount of gas introduced into the cutting chamber in accordance with the disclosure, measured for example as a volumetric flow rate or mass flow, can also be used to influence the solidification process in a targeted manner, as a further variable in the process of solidification and formation of pellets with as good and homogeneous a quality as possible. According to the disclosure, chemical reactions triggered by the gas introduced into the cutting chamber are also possible, be it by gas molecules reacting with molecules of the plastic, or the like. As an alternative instead of air, it is also in accordance with the disclosure to introduce other gases or mixtures of gases directly or indirectly into the cutting chamber, for example inert gases, argon, nitrogen or the like, preferably gases of the kind that do not react with the molecules contained in the pellets. A further alternative is to introduce liquids other than water directly or indirectly into the cutting chamber, including mixtures of water and other liquids, for example.

[0011] According to an embodiment of the pelletizing apparatus according to the disclosure, a gas nozzle arrangement connectable to the gas inlet is provided with a plurality of nozzle orifices for discharging the gas directly or indirectly into the cutting chamber, the gas nozzle arrangement being arranged directly inside the cutting chamber or inside a (water) feed channel connected to the cutting chamber, in such a way that a large number of gas bubbles can be formed in the cutting chamber which can be filled with water or some other liquid. Such a gas nozzle arrangement can support the formation of bubbles, so that a large number of small gas bubbles, for example, are produced, which then interact intensively with the pellet particles in the cutting chamber.

[0012] According to another embodiment, the gas nozzle arrangement is arranged upstream from the outlet of the cutting chamber, preferably directly in or at thecutting chamber or indirectly in or at a (water) feed channel, preferably inside a (water) feed pipe. In this way, the gas can be alternatively or cumulatively introduced directly and / or indirectly into the cutting chamber. This advantageously allows a large number of gas bubbles to form, which then interact advantageously intensively with the cut pellets introduced into the cutting chamber. Due to the buoyancy of the gas, preferably the air, in the flowing water, the velocity components of the flowing water and of the buoyant gas can add up, with the result that the gas bubbles proceed at increased speed into the region where the pellets are suspended in the water, which can affect how the pellets are formed. This can have a further positive effect on the homogeneity and quality of the pellets being formed. According to the disclosure, the pellets formed come even closer to a compact shape, in particular to an optimal spherical shape, although the spherical shape is often only aimed for, but only rarely is an exact spherical shape achieved in practice. Experiments have shown that the disclosure achieves an improved approximation to a spherical or compact shape compared to the prior art. According to the disclosure, the roundness of the pellets is increased.

[0013] It is therefore expedient if the gas nozzle arrangement is arranged below the die plate assembly.

[0014] Another embodiment of the disclosure is characterized in that the gas nozzle arrangement is arranged inside a water feed pipe that forms the water feed channel and which is preferably substantially vertical in orientation and preferably arranged substantially below the die plate assembly and in operation feeds the water / gas mixture to the cutting chamber. This allows a large number of gas bubbles to be formed intensively and homogeneously in the region where water is fed in, thus achieving a strong interaction between the gas bubbles floating in the flow of water and the solidifying pellets. By using a (water) feed pipe in which the gas nozzle arrangement is arranged, a very simple design is realized, and gas connections in the immediate vicinity of the cutting chamber are avoided.

[0015] According to an advantageous development of the disclosure, it is proposed with a view to favorable and intensive mixing of air bubbles and pellets that the melt outlets of the die plate assembly are arranged in such a way that granulateparticles and the water / gas mixture move towards each other at least partially inside the cutting chamber, substantially at an angle between 60° and 120°, preferably at an angle of about 90°.

[0016] The pelletizing apparatus is preferably designed in such a way that a water / granulate discharge channel for discharging the granulate / water / gas mixture is arranged on an upper section of the cutting chamber that is preferably in the form of a pipe and is preferably arranged substantially vertically in sections at least in order to discharge the granulate / water / gas mixture during operation and to convey it further in order to separate and dry the pellets.

[0017] Bubbles can be formed particularly intensively by feeding a high volumetric flow rate of gas and by designing the gas nozzle arrangement as a ring nozzle.

[0018] The advantages described in the foregoing are achieved in equal measure by an underwater pelletizing method for producing granulate from free-flowing curable plastic, preferably using the pelletizing apparatus according to the disclosure, wherein the method according to the disclosure comprises the following steps, wherein liquid plastic in the form of a melt is fed to a die plate assembly having a die plate and is discharged in the form of a plurality of melt strands from the die plate through a plurality of flow channels in the die plate, the discharged melt strands are divided into separate granulate particles by means of a cutting device, the granulate particles are discharged into a cutting chamber filled with water or some other liquid, water or some other liquid is introduced into cutting chamber through at least one (water) inlet and water or some other liquid and granulate is conveyed out of the cutting chamber through at least one outlet, wherein gas is introduced into the cutting chamber through a gas inlet in such a way that the gas interacts with granulate particles inside the cutting chamber filled with water or other liquid. With regard to the technical effects and advantages and to avoid repetitions, reference is made to the above descriptions of the apparatus.

[0019] It is preferable that gas is fed through the gas inlet to a gas nozzle arrangement connected thereto and having a plurality of nozzle orifices, that the gas is discharged from the nozzle orifices into the cutting chamber to form a large number ofgas bubbles inside the cutting chamber or inside a (water) feed channel connected to the cutting chamber, and that the gas bubbles interact in the cutting chamber with the granulate particles and thus affect the shape of the granulates or particles when they solidify, which advantageously results in greater compactness or roundness of the pellets.

[0020] It is also that gas is introduced through the gas nozzle arrangement upstream from the outlet of the cutting chamber, preferably directly in or at the cutting chamber or indirectly in or at a (water) feed channel formed by a (water) feed pipe. It is preferable that the gas nozzle arrangement is arranged below the die plate assembly and / or that gas is introduced by means of the gas nozzle arrangement into a (water) feed pipe forming the (water) feed channel, which is preferably substantially vertical in orientation and preferably arranged substantially below the die plate assembly and in operation feeds a water / gas mixture to the cutting chamber.

[0021] In one aspect, an underwater pelletizing apparatus includes a die plate assembly having a melt inlet for feeding liquid melt and melt outlets for discharging a plurality of melt strands into an adjacent cutting chamber. The underwater pelletizing apparatus in addition includes a cutting device for producing granulate particles from the melt strands. The underwater pelletizing apparatus moreover includes a cutting chamber that is adjacent to the die plate assembly and can be filled with water or some other liquid, which has at least one (water) inlet for feeding water or other liquid into the cutting chamber, and which has at least one (water) granulate outlet for discharging a mixture of water or other liquid and granulate from the cutting chamber. The underwater pelletizing apparatus also includes characterized by at least one gas inlet, connectable to a gas source, for feeding gas directly or indirectly into the cutting chamber in such a way that fed gas can interact inside the cutting chamber with granulate.

[0022] There has thus been outlined, rather broadly, certain aspects of the disclosure in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional aspects of the disclosure that will be described below and which will form the subject matter of the claims appended hereto.

[0023] In this respect, before explaining at least one aspect of the disclosure in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The disclosure is capable of aspects in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting.

[0024] As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the disclosure. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the disclosure.BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The disclosure shall now be described with reference to embodiments and to the attached Figures, in which:

[0026] Fig. 1 : shows a schematic view of a first embodiment of a pelletizing apparatus and a pelletizing method;

[0027] Fig. 2: shows a perspective view of a second embodiment of a pelletizing apparatus;

[0028] Fig. 3: shows a side view of the pelletizing apparatus in Fig. 2;

[0029] Fig. 4: shows an enlarged side view of part of the pelletizing apparatus, with gas bubbles shown;

[0030] Fig. 5: shows a front view of the pelletizing apparatus;

[0031] Fig. 6: shows a cutaway view of the pelletizing apparatus;

[0032] Fig. 7: shows a section of the pelletizing apparatus with a gas nozzle arrangement;

[0033] Fig. 8: shows a partial section of Fig. 7;

[0034] Fig. 9: shows a section of the pelletizing apparatus with a gas nozzle arrangement according to an alternative embodiment;

[0035] Fig. 10: shows a partial section of Fig. 9;

[0036] Fig. 11 : shows a section of the pelletizing apparatus with a gas nozzle arrangement according to another embodiment;

[0037] Fig. 12: shows a partial section of Fig. 11 ;

[0038] Fig. 13: shows granulate produced according to the prior art, without gassing, in a first experiment;

[0039] Fig. 14: shows granulate produced according to the disclosure, by a method according to the disclosure in an apparatus according to the disclosure, in a first experiment

[0040] Fig. 15: shows granulate produced according to the prior art, without gassing, in a second experiment; and

[0041] Fig. 16: shows granulate produced according to the disclosure, by a method according to the disclosure in an apparatus according to the disclosure, in a second experiment.DETAILED DESCRIPTION

[0042] The two embodiments shown in Fig. 1 and in Figs. 2 - 12 each show an (underwater) pelletizing apparatus 1 and a method for producing granulate 3 or pellets 3 from free-flowing curable plastic, for example a polymer, whereby the apparatus can also be referred to as a pelletizer 1 . Figs. 1 and 4 show a large number of pellet particles or granulate 3 in schematic views. In the two embodiments, the same reference signs are used for identical or substantially identical parts and components.

[0043] In the pelletizing apparatus 1 shown in Fig. 1 and Fig. 2, a die plate assembly 6 of the kind known from the prior art, which typically has a perforated disk having a plurality of cylindrical passages, is shown, which has a melt inlet 8 for feeding liquid melt and melt outlets for discharging a plurality of melt strands into an adjacent cutting chamber 2. Cutting chamber 2 is also referred to as water box 2, because in operation it is filled with water that flows through cutting chamber 2. Other liquids or fluid mixtures may also be used in apparatus 1 instead of water.

[0044] A cutting device 12, which is not shown in Fig. 1 , but is shown in Figs. 2 - 6 and described in more detail with reference to the latter, comprises a drive means and a blade which can be rotated by the drive means, and is used to produce individual particles of granulate 3 from the melt strands which are discharged from die assembly 6, which preferably has a perforated disk, into cutting chamber 2, which is arranged adjacent to die plate assembly 6 and can be filled with water or some other fluid. Cutting chamber 2 has (at least) one water inlet 14 preferably arranged in the lower region, for feeding water, indirectly in this example, into cutting chamber 2 and (at least) one water / granulate outlet 16 arranged in the upper region for discharging a mixture of water and granulate and gas out of the cutting chamber. The water inlet 14 of cutting chamber 2 is coupled to a water feed pipe 38 connected thereto, which forms a water feed channel 36 for feeding water into cutting chamber 2. Outlet 16 in the upper region of cutting chamber 2 is coupled to a water / granulate discharge pipe 18, through which granulate 3, together with water and gas, can be discharged upwards and fed to a separator, of the kind known per se to a person skilled in the art, for separating the produced granulate 3 from the water, and preferably to a drier, not shown, for drying the produced granulate 3.

[0045] Fig. 1 , and more specifically the initial example according to Figs. 2 - 11 , shows apparatus 1 having at least one gas inlet 19 connectable to a gas source, not shown, for introducing gas into cutting chamber 2, in such a way that introduced gas, in particular and preferably in the form of moving bubbles, can interact inside cutting chamber 2 with granulate 3. In embodiments, gas inlet 19 is arranged inside the water feed pipe 38 connected to cutting chamber 2, such that introduced gas can be introduced indirectly through feed pipe 38 and then directly through inlet 14 into cutting chamber 2, in the embodiment as a water / gas mixture flowing through water feed pipe 38 and inlet 14 into cutting chamber 2. It is also within the scope of the disclosure that gas can be introduced into cutting chamber 2 through a gas inlet 19 located inside cutting chamber 2, or through a gas inlet 19 formed in a wall of cutting chamber 2, and is introduced from a gas source during operation. The gas introduced is preferably air and preferably forms a large number of gas bubbles gas bubbles that are introducedindirectly into cutting chamber 2 by flowing through feed pipe 38, as shown, or directly into cutting chamber 2, as described, where they interact with the particles of granulate 3.

[0046] Water or some other liquid can be fed from a reservoir by means of a pump through a (water) connection 40 as shown in Figs. 1 and 4, initially in a singlephase stream indicated by arrow 39, preferably upwards through vertical feed pipe 39. Gas inlet 19 is connected to a gas nozzle arrangement 20 having a plurality of nozzle orifices 44 for discharging gas into cutting chamber 2. In a manner not shown, gas nozzle arrangement 20 may be arranged inside cutting chamber 2 or, as shown in the embodiments, inside a (water) feed channel 36 formed by feed pipe 38 and connected to cutting chamber 2, wherein in both cases a large number of gas bubbles 24 are preferably formed in the cutting chamber that can be filled with water. A gas stream, indicated here by arrow 41 and in the form of bubbles 24, flows together with the fed water (arrow 39) in a two-phase stream through feed pipe 38 and through inlet 19 into cutting chamber 2, where it can interact with the produced granules 3. A stream of granulate 3, illustrated by arrow 43, then flows together with water and gas in three- phase stream (consisting of granulate particles, water and air) further upwards out of cutting chamber 2 through outlet 16 and discharge pipe 18, which is preferably arranged at least partially vertical, for further processing, in particular for separation and drying of granulate 3.

[0047] Figs. 1 and 4 - 6 illustrate the water / granulate discharge channel 17 for discharging the granulate / water / gas mixture and arranged at the upper section of cutting chamber 2, which is in the form of a discharge pipe and is preferably arranged substantially vertically in sections at least in order to discharge the granulate / water / gas mixture during operation.

[0048] As can be seen from Figs. 2 and 3 in particular, apparatus 1 has a machine frame 32 which can preferably be moved by means of rollers and on which cutting device 12 comprising a rotating blade and drive means 34 in the form of an electric motor, and a gear transmission connected between drive means 34 and the blade are arranged. In a manner known per se, the rotating blade is driven by means ofa preferably horizontally arranged shaft 33 (Figs. 4 and 6) extending through the interior of cutting chamber 2, wherein the cutting edges of the blade are in contact with the perforated disk and divide the emerging melt that is still liquid into particles, which then form granulate 3 and solidify in the water or other liquid in cutting chamber 2. Shaft 33 for driving the blade is also shown in Fig. 6.

[0049] As shown in the embodiment in Fig. 1 , cutting chamber 2 is mounted within a piping system comprising water feed pipe 38 and a water / granulate discharge pipe 18, which are each coupled to other pipelines. A three-phase stream of water (or other liquid), pellets 3 and gas, in particular air, is formed in the upper discharge pipe 18. As shown by Figs. 1 and 4, these three components of the three-phase stream flow in the direction shown by arrows 39, 41 , 43.

[0050] In a manner not shown, water connection 40 is connected to further pipelines in order to feed the water or other liquid from below through connection 40, from a reservoir and with the aid of a pump. Discharge pipe 18 can also be seen at the top of Figs. 2 - 4. The water or other liquid can be recycled.

[0051] As well illustrated by Figs. 1 - 4, the gas nozzle arrangement 20 for introducing gas into the water or other liquid through the plurality of nozzle orifices 44 is positioned inside feed pipe 38 downstream from (water) connection 40. At the same time, the gas nozzle arrangement is arranged upstream from the outlet 6 of cutting chamber 2, or is arranged directly in or at cutting chamber 2 in a manner not shown, or is arranged as shown in the embodiment in or at a water feed channel 36, preferably inside a water feed pipe 38. In the embodiment shown, the gas nozzle arrangement 20 is preferably positioned at a section of pipe 38 which is detachably attached to the other section of pipe 38. In an embodiment, nozzle arrangement 20 is arranged accordingly inside the water feed channel 36 connected to cutting chamber 2, in such a way that gas can flow in through gas inlet 19 and then into cutting chamber 2 through inlet 14. According to the disclosure, this way of introducing gas into cutting chamber 2, or also the direct introduction of gas, results in gas, preferably a large number of gas bubbles, being formed in the cutting chamber 2 filled with water. Gas nozzle arrangement 20 is arranged upstream from water inlet 14 in the region where water is fed in. As can alsobe seen from the figures, gas nozzle arrangement 20 is arranged below die plate assembly 6. In this way, the gas bubbles 24 that form rise upwards and reach the region of the melt particles discharged from die assembly 6 into cutting chamber 2, which form the granulate 3 and solidify in the water inside cutting chamber 2 as the process continues.

[0052] It can be seen from Fig. 4 that the melt outlets of perforated disk of the die plate assembly are arranged in such a way that granulate particles and the water / gas mixture move towards each other at least partially inside cutting chamber 2, substantially at an angle between 60° and 120°, preferably at an angle of about 90°. The channels inside the perforated disk are arranged substantially horizontally, and the melt flows from right to left into cutting chamber 2, whereas the (water / )gas mixture flows substantially vertically upwards through inlet 14 into melting chamber 2; see also arrows 39 and 41 in Fig. 1 . During operation, an interaction thus occurs between the gas bubbles in the water and the particles of granulate 3. The mass or volumetric flow rate of the water, the gas and melt can be adjusted and varied by adjusting the pumps, the gas supply and the water supply accordingly, and can be optimized in such a way that granulate 3 is produced in good quality, in particular in compact form.

[0053] As shown in Fig. 1 , gas can be supplied to gas nozzle arrangement 20 by means of a preferably horizontally arranged pipe 29. Pipe 29 is connected, in a manner not shown, to a source of compressed gas. It extends through an opening in the wall of feed pipe 38. The orifices 44 of gas nozzle arrangement 20, which in the embodiment are arranged in the interior of the feed pipe or, alternatively, directly in cutting chamber 2, are used to release the gas from nozzle arrangement 20 into the water or other liquid and ultimately into cutting chamber 2; see also Figs. 8 - 12. Orifices 44 may be arranged along a ring, a line, or in any random pattern. Figs. 6 and 10 illustrate how nozzle arrangement 20 is designed as a ring nozzle having a plurality of orifices 44 which lie on a circle.

[0054] The cross-sectional view in Fig. 6 shows feed pipe 38 with gas nozzle arrangement 20, arranged therein, designed as a ring nozzle having a plurality of orifices 44. Gas, together with water, enters the interior of cutting chamber 2 throughinlet 14. Granulate in the form of particles made using nozzle arrangement 6 and cutting device 12 is likewise fed into the cutting chamber, where the granulate 3 comes into contact with the water and the gas, in particular with gas bubbles 24. The mixture of granulate 3, water and gas flows out of cutting chamber 2 through outlet 16 and through pipe 18.

[0055] Figs. 7 and 8 illustrate gas nozzle arrangement 20 and pipe 29 (pipeline 29) for feeding gas / air from a compressed gas source to nozzle arrangement 20. Gas is fed through pipe 29 into the interior of the section of feed pipe 38.

[0056] Figs. 9 and 10 show that gas nozzle arrangement 20 can be designed as a ring nozzle having a plurality of orifices 44, such that a large number of gas bubbles are formed in the water stream.

[0057] Figs. 11 and 12 show an alternative embodiment of a nozzle arrangement 20. A plurality of bores with orifices 44 are formed here in the wall of a section of (water) feed pipe 38, through which orifices the gas can be fed into the interior of feed pipe 38. To that end, pipe 29 is connected to an annular space 46 (Fig. 12), and the gas can flow out of the annular space 46 through orifices 44 into the interior of feed pipe 38.

[0058] The figures described above also illustrate the underwater pelletizing method according to the disclosure for producing granulate 3 from free-flowing, curable plastic, which method is preferably carried out using pelletizing apparatus 1 . Liquid plastic in the form of a melt is fed to a die plate assembly 6 having a die plate and is discharged in the form of a plurality of melt strands from the die plate through a plurality of flow channels in the die plate. By means of cutting device 12 having at least one rotating blade, a large number of individual particles forming the granulate are produced at the die plate. The granulate particles are discharged into cutting chamber 2 (water box), which is filled with water or some other liquid. Water or some other liquid is fed through at least one (water-)inlet 14 into cutting chamber 2. Gas is fed through a gas inlet 19 directly or indirectly into cutting chamber 2 through a feed channel 36. The gas fed into cutting chamber 2 interacts with granulate particles inside the cutting chamber 2 filled with water or other liquid. Water or some other liquid and granulate 3 and gas are conveyed out of cutting chamber 2 through at least one outlet 17. Gas is preferably fedthrough gas inlet 19 to the gas nozzle arrangement 20 which is connected thereto and which has a plurality of nozzle orifices 44. The gas coming out of nozzle orifices 44 forms a large number of gas bubbles 24 inside cutting chamber 2, or previously inside the (water) feed channel 36 connected to cutting chamber 2. According to the embodiment, it is that gas is introduced by means of gas nozzle arrangement 20 into (water) feed channel 36, which is preferably substantially vertical in orientation and preferably arranged substantially below die plate assembly plate assembly 6 and in operation feeds a (water / )gas mixture to cutting chamber 2.

[0059] It is preferred that gas, preferably compressed air, is supplied continuously in accordance with the disclosure. A continuous supply of gas is understood here to mean that the volumetric flow or mass flow of the gas is constant, whereby the rate can be varied, i.e. different volumetric or mass flow rates may can be set. Alternatively, however, it is also possible in the method according to the disclosure, using the apparatus according to the disclosure, to supply the gas with variable volumetric or mass flow rates. For example, it is also possible according to the disclosure to supply to supply the gas intermittently, i.e. to switch on the gas supply during a particular phase, and to pause it during a different phase. For persons skilled in the art, it makes sense to implement a continuous or also variable or discontinuous, intermittent supply of gas. For example, respective valves can be switched on or off, and / or the gas supply can be varied, or different volumetric or mass flow rates adjusted, by means of respective throttle valves. A person skilled in the art will understand that gas, in particular air, can be provided from a gas source such as a compressed gas system. The gas supply can be controlled and adjusted by controlling the device accordingly.

[0060] Fig. 13 shows a schematic image of plastic granulate 3 produced according to the prior art. Fig. 14 shows plastic granulate 3 produced under similar production conditions according to the production method according to the disclosure, using an apparatus 1 according to the disclosure. Figs. 13 and 14 show different results, without the gassing according to the disclosure (Fig. 13) and with the gassing according to the disclosure (Fig. 14).

[0061] In this experiment, the following parameters were set: the experimental set-up as shown in the embodiment in Fig. 1 ; mass flow rate of plastic melt: 150 kg / hr; temperature of process water: 60° C.

[0062] Very irregular shape of granules (Fig. 13): Fig. 13 shows that particles produced according to the prior art are elongate and in some cases far from a compact, ideally spherical shape. The ratio of the smallest length of a particle to the longest length is far from the value 1. The value 1 is achieved with an ideal sphere.

[0063] With gassing according to the disclosure: mass flow rate of the plastic melt: 150 kg / hr, temperature of process water: 60° C, and 10% gassing with compressed air, and the shape of the granules is significantly improved in the sense of being more compact and rounder and closer to a spherical shape (Fig. 14). It can be seen from the shape of the particles in Fig. 14 (according to the disclosure) in comparison with Fig. 13 (according to the prior art) that the particles are significantly closer to a spherical shape and significantly more compact due to the gassing according to the disclosure. The ratio of the smallest width to the largest length is closer to the value 1 for an ideal spherical shape.

[0064] Fig. 15 shows a schematic image of plastic granulate 3 produced according to the prior art. Fig. 16 shows plastic granulate produced under similar production conditions according to the production method according to the disclosure, using an apparatus 1 according to the disclosure.

[0065] Figs. 15 and 16 show different results, without the gassing according to the disclosure (Fig. 15) and with the gassing according to the disclosure (Fig. 16). In this experiment, the following parameters were set: the experimental set-up as shown in the embodiment in Fig. 1 , mass flow rate of plastic melt: 200 kg / hr, temperature of process water: 50° C that results in a shape of granules that are very irregular (Fig. 15).

[0066] With gassing according to the disclosure: mass flow rate of the plastic melt: 200 kg / hr, temperature of process water: 50° C, 50% gassing with compressed air, results in little change in the shape of granules (Fig. 16), but it is clearly evident that the shape of the granules is rounded and closer to that of a sphere.

[0067] Measurements show that an improvement in the roundness of the granulate 3 is achieved by gassing according to the disclosure (Fig. 16). The roundness here improves from 0.661 to 0.765, where the number 1 .0 stands for spherically round. The roundness is determined here by calculating the quotient of the smallest length divided by the largest length of a particle.

[0068] The surface area of the individual granules is also reduced, thus indicating a positive change towards a more spherical shape.

[0069] The comparison of Figs. 13 and 15 (the prior art) with Figs. 14 and 16 (the disclosure) shows that gassing the process water in accordance with the disclosure affects the shape of the granulate formed during the solidification process. The interaction of gas bubbles in the process water in the region of cutting chamber 2 during the solidification of the granulate particles, in accordance with the disclosure, results in an improved quality of the granulate 3, such that the granulate is more compact and closer to the spherical shape than in the prior art.

[0070] List of reference signs1 Underwater pelletizing apparatus2 Cutting chamber (water box)3 Granulate or pellet (particles)6 Die plate assembly7 Die plate8 Melt inlet10 Melt outlets12 Cutting device14 (Water) inlet16 (Water / )g ran ulate outlet17 (WaterZ)granulate discharge channel18 (Water / )g ran ulate discharge pipe19 Gas inlet20 Gas nozzle arrangement24 Gas bubbles29 Pipe31 Transmission gear32 Machine frame33 Drive shaft34 Drive means (cutting device)35 Blade36 (Water) feed channel38 (Water) feed pipe39 Arrow showing direction of water flow40 (Water) connection41 Arrow showing direction of gas flow43 Arrow showing direction of granulate flow44 Nozzle orifices46 Annular space

[0071] One EXAMPLE: an underwater pelletizing apparatus includes a die plate assembly having a melt inlet for feeding liquid melt and melt outlets for discharging a plurality of melt strands into an adjacent cutting chamber. The underwater pelletizing apparatus in addition includes a cutting device for producing granulate particles from the melt strands. The underwater pelletizing apparatus moreover includes a cutting chamber that is adjacent to the die plate assembly and can be filled with water or some other liquid, which has at least one (water) inlet for feeding water or other liquid into the cutting chamber, and which has at least one (water) granulate outlet for discharging a mixture of water or other liquid and granulate from the cutting chamber. The underwater pelletizing apparatus also includes characterized by at least one gas inlet, connectable to a gas source, for feeding gas directly or indirectly into the cutting chamber in such a way that fed gas can interact inside the cutting chamber with granulate.

[0072] The above-noted EXAMPLE may further include any one or a combination of more than one of the following EXAMPLES: The pelletizing apparatus of the abovenoted EXAMPLE characterized in that a gas nozzle arrangement connectable to the gas inlet is provided with a plurality of nozzle orifices for discharging the gas directly orindirectly into the cutting chamber, where the gas nozzle arrangement is arranged directly inside the cutting chamber or inside a (water) feed channel connected to the cutting chamber, in such a way that a large number of gas bubbles can be formed in the cutting chamber which can be filled with water or some other liquid. The pelletizing apparatus of the above-noted EXAMPLE characterized in that the gas nozzle arrangement is arranged upstream from the outlet of the cutting chamber, preferably directly in or at the cutting chamber or indirectly in or at a (water) feed channel, preferably inside a (water) feed pipe. The pelletizing apparatus of the above-noted EXAMPLE characterized in that the gas nozzle arrangement is arranged below the die plate assembly. The pelletizing apparatus of the above-noted EXAMPLE, characterized in that the gas nozzle arrangement is arranged inside a water feed pipe that forms the water feed channel and which is preferably substantially vertical in orientation and preferably arranged substantially below the die plate assembly and in operation feeds a water / gas mixture to the cutting chamber.

[0073] One EXAMPLE: an underwater pelletizing apparatus includes a die plate assembly having a melt inlet for feeding liquid melt and melt outlets for discharging a plurality of melt strands into an adjacent cutting chamber. The underwater pelletizing apparatus in addition includes a cutting device for producing granulate particles from the melt strands. The underwater pelletizing apparatus moreover includes a cutting chamber that is adjacent to the die plate assembly and can be filled with water or some other liquid, which has at least one inlet for feeding water or other liquid into the cutting chamber, and which has at least one granulate outlet for discharging a mixture of water or other liquid and granulate from the cutting chamber. The underwater pelletizing apparatus also includes where at least one gas inlet, connectable to a gas source, for feeding gas directly or indirectly into the cutting chamber in such a way that fed gas can interact inside the cutting chamber with granulate.

[0074] The above-noted EXAMPLE may further include any one or a combination of more than one of the following EXAMPLES: The pelletizing apparatus of the abovenoted EXAMPLE where a gas nozzle arrangement connectable to the gas inlet is provided with a plurality of nozzle orifices for discharging the gas directly or indirectlyinto the cutting chamber, and where the gas nozzle arrangement is arranged directly inside the cutting chamber or inside a feed channel connected to the cutting chamber, in such a way that a large number of gas bubbles can be formed in the cutting chamber which can be filled with water or some other liquid. The pelletizing apparatus of the above-noted EXAMPLE where the gas nozzle arrangement is arranged upstream from the outlet of the cutting chamber. The pelletizing apparatus of the above-noted EXAMPLE where the gas nozzle arrangement is arranged upstream from the outlet of the cutting chamber directly in or at the cutting chamber or indirectly in or at a feed channel. The pelletizing apparatus of the above-noted EXAMPLE where the gas nozzle arrangement is arranged upstream from the outlet of the cutting chamber directly in or at the cutting chamber or indirectly in or at a feed channel inside a feed pipe. The pelletizing apparatus of the above-noted EXAMPLE where the gas nozzle arrangement is arranged below the die plate assembly. The pelletizing apparatus of the above-noted EXAMPLE where the gas nozzle arrangement is arranged inside a water feed pipe that forms the water feed channel and which is preferably substantially vertical in orientation and preferably arranged substantially below the die plate assembly and in operation feeds a water / gas mixture to the cutting chamber. The pelletizing apparatus of the above-noted EXAMPLE where the melt outlets of the die plate assembly are arranged in such a way that granulate particles and the water / gas mixture move towards each other at least partially inside the cutting chamber, substantially at an angle between 60 and 120, preferably at an angle of about 90. The pelletizing apparatus of the abovenoted EXAMPLE where the gas nozzle arrangement is in a form of a ring nozzle. The pelletizing apparatus of the above-noted EXAMPLE where a water / granulate discharge channel for discharging the granulate mixture and / or water mixture is arranged on an upper section of the cutting chamber that is preferably in a form of a pipe and is preferably arranged substantially vertically in sections at least in order to discharge the granulate mixture, water mixture, and / or gas mixture during operation. The underwater of the above-noted EXAMPLE preferably using the pelletizing apparatus in which: liquid plastic in a form of a melt is fed to a die plate assembly having a die plate and is discharged in a form of a plurality of melt strands from the die plate through a plurality offlow channels in the die plate, the discharged melt strands are divided into separate granulate particles by means of a cutting device, the granulate particles are discharged into a cutting chamber filled with water or some other liquid, water or some other liquid is introduced into cutting chamber through at least one inlet, and water or some other liquid and granulate is conveyed out of the cutting chamber through at least one outlet, where gas is introduced into the cutting chamber through a gas inlet in such a way that the gas interacts with granulate particles inside the cutting chamber filled with water or other liquid. The underwater of the above-noted EXAMPLE where gas is fed through the gas inlet to a gas nozzle arrangement connected thereto and having a plurality of nozzle orifices, and where the gas is discharged from the nozzle orifices into the cutting chamber to form a large number of gas bubbles inside the cutting chamber or inside a feed channel connected to the cutting chamber, and the gas bubbles interact in the cutting chamber with the granulate particles and thus affect a shape of the granulates or particles when they solidify. The underwater of the above-noted EXAMPLE where gas is introduced through a nozzle arrangement downstream from the inlet in a region where water is fed in, where a gas nozzle arrangement is preferably arranged below the die plate assembly. A method according to at least one of the preceding EXAMPLES.

[0075] It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the disclosure. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0076] It will be understood that when an element such as a layer, region, or substrate is referred to as being "on" or extending "onto" another element, it can be directly on or extend directly onto another element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" or extending "directly onto" another element, there are no intervening elements present. Likewise, it will be understood that when an element such as a layer, region, or substrate is referredto as being "over" or extending "over" another element, it can be directly over or extend directly over another element or intervening elements may also be present. In contrast, when an element is referred to as being "directly over" or extending "directly over" another element, there are no intervening elements present. It will also be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to another element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present.

[0077] Relative terms such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical" may be used herein to describe a relationship of one element, layer, or region to another element, layer, or region as illustrated in the Figures. It will be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures.

[0078] The terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes," and / or "including" when used herein specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0079] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0080] The many features and advantages of the disclosure are apparent from the detailed specification, and, thus, it is intended by the appended claims to cover allsuch features and advantages of the disclosure which fall within the true spirit and scope of the disclosure. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the disclosure to the exact construction and operation illustrated and described, and, accordingly, all suitable modifications and equivalents may be resorted to that fall within the scope of the disclosure.

Claims

CLAIMS:1 . An underwater pelletizing apparatus for producing granulate from free-flowing curable plastic, comprising: a die plate assembly having a melt inlet for feeding liquid melt and melt outlets for discharging a plurality of melt strands into an adjacent cutting chamber, a cutting device for producing granulate particles from the melt strands, and a cutting chamber that is adjacent to the die plate assembly and can be filled with water or some other liquid, which has at least one (water) inlet for feeding water or other liquid into the cutting chamber, and which has at least one (water) granulate outlet for discharging a mixture of water or other liquid and granulate from the cutting chamber, characterized by at least one gas inlet, connectable to a gas source, for feeding gas directly or indirectly into the cutting chamber in such a way that fed gas can interact inside the cutting chamber with granulate.

2. The pelletizing apparatus according to claim 1 , characterized in that a gas nozzle arrangement connectable to the gas inlet is provided with a plurality of nozzle orifices for discharging the gas directly or indirectly into the cutting chamber, wherein the gas nozzle arrangement is arranged directly inside the cutting chamber or inside a (water) feed channel connected to the cutting chamber, in such a way that a large number of gas bubbles can be formed in the cutting chamber which can be filled with water or some other liquid.

3. The pelletizing apparatus according to claim 2, characterized in that the gas nozzle arrangement is arranged upstream from the outlet of the cutting chamber, preferably directly in or at the cutting chamber or indirectly in or at a (water) feed channel, preferably inside a (water) feed pipe.

4. The pelletizing apparatus according to claim 2 or 3, characterized in that the gas nozzle arrangement is arranged below the die plate assembly.

5. The pelletizing apparatus according to at least one of claims 2 to 4, characterized in that the gas nozzle arrangement is arranged inside a water feed pipe that forms the water feed channel and which is preferably substantially vertical in orientation and preferably arranged substantially below the die plate assembly and in operation feeds a water / gas mixture to the cutting chamber.

6. The pelletizing apparatus according to at least one of the preceding claims, characterized in that the melt outlets of the die plate assembly are arranged in such a way that granulate particles and the water / gas mixture move towards each other at least partially inside the cutting chamber, substantially at an angle between 60° and 120°, preferably at an angle of about 90°.

7. The pelletizing apparatus according to at least one of the preceding claims, characterized in that a water / granulate discharge channel for discharging the granulate(Zwater) mixture is arranged on an upper section of the cutting chamber that is preferably in the form of a pipe and is preferably arranged substantially vertically in sections at least in order to discharge the granulate / water / gas mixture during operation.

8. The pelletizing apparatus according to at least one of the preceding claims, characterized in that the gas nozzle arrangement is in the form of a ring nozzle.

9. An underwater pelletizing method for producing granulate from free-flowing curable plastic, preferably using the pelletizing apparatus according to at least one of the preceding claims, in which: liquid plastic in the form of a melt is fed to a die plate assembly having a die plate and is discharged in the form of a plurality of melt strands from the die plate through a plurality of flow channels in the die plate,the discharged melt strands are divided into separate granulate particles by means of a cutting device, the granulate particles are discharged into a cutting chamber filled with water or some other liquid, water or some other liquid is introduced into cutting chamber through at least one (water) inlet, and water or some other liquid and granulate is conveyed out of the cutting chamber through at least one outlet, characterized in that gas is introduced into the cutting chamber through a gas inlet in such a way that the gas interacts with granulate particles inside the cutting chamber filled with water or other liquid.

10. The method according to claim 9, wherein gas is fed through the gas inlet to a gas nozzle arrangement connected thereto and having a plurality of nozzle orifices, and wherein the gas is discharged from the nozzle orifices into the cutting chamber to form a large number of gas bubbles inside the cutting chamber or inside a (water) feed channel connected to the cutting chamber, and the gas bubbles interact in the cutting chamber with the granulate particles and thus affect the shape of the granulates or particles when they solidify.11 . A method according to at least one of the preceding claims, characterized in that gas is introduced through the nozzle arrangement downstream from the (water) inlet in the region where water is fed in, wherein the gas nozzle arrangement is preferably arranged below the die plate assembly.

12. A method according to at least one of the preceding claims, characterized in that gas is introduced by means of the gas nozzle arrangement into a (water) feed pipe forming the (water) feed channel, which is preferably substantially vertical in orientationand preferably arranged substantially below the die plate assembly and in operation feeds a water / gas mixture to the cutting chamber.

13. An underwater pelletizing apparatus for producing granulate from free-flowing curable plastic, comprising: a die plate assembly having a melt inlet for feeding liquid melt and melt outlets for discharging a plurality of melt strands into an adjacent cutting chamber, a cutting device for producing granulate particles from the melt strands, and a cutting chamber that is adjacent to the die plate assembly and can be filled with water or some other liquid, which has at least one inlet for feeding water or other liquid into the cutting chamber, and which has at least one granulate outlet for discharging a mixture of water or other liquid and granulate from the cutting chamber, wherein at least one gas inlet, connectable to a gas source, for feeding gas directly or indirectly into the cutting chamber in such a way that fed gas can interact inside the cutting chamber with granulate.

14. The pelletizing apparatus according to claim 13, wherein a gas nozzle arrangement connectable to the gas inlet is provided with a plurality of nozzle orifices for discharging the gas directly or indirectly into the cutting chamber, and wherein the gas nozzle arrangement is arranged directly inside the cutting chamber or inside a feed channel connected to the cutting chamber, in such a way that a large number of gas bubbles can be formed in the cutting chamber which can be filled with water or some other liquid.

15. The pelletizing apparatus according to claim 14, wherein the gas nozzle arrangement is arranged upstream from the outlet of the cutting chamber.

16. The pelletizing apparatus according to claim 14, wherein the gas nozzle arrangement is arranged upstream from the outlet of the cutting chamber directly in or at the cutting chamber or indirectly in or at a feed channel.

17. The pelletizing apparatus according to claim 14, wherein the gas nozzle arrangement is arranged upstream from the outlet of the cutting chamber directly in or at the cutting chamber or indirectly in or at a feed channel inside a feed pipe.

18. The pelletizing apparatus according to claim 14, wherein the gas nozzle arrangement is arranged below the die plate assembly.

19. The pelletizing apparatus according to at least one of claim 14, wherein the gas nozzle arrangement is arranged inside a water feed pipe that forms the water feed channel.

20. The pelletizing apparatus according to at least one of claim 14, wherein the gas nozzle arrangement is arranged inside a water feed pipe that forms the water feed channel and which is substantially vertical in orientation.21 . The pelletizing apparatus according to at least one of claim 14, wherein the gas nozzle arrangement is arranged inside a water feed pipe that forms the water feed channel and which is substantially vertical in orientation and arranged substantially below the die plate assembly and in operation feeds a water / gas mixture to the cutting chamber.

22. The pelletizing apparatus according to claim 19, wherein the melt outlets of the die plate assembly are arranged in such a way that granulate particles and the water / gas mixture move towards each other at least partially inside the cutting chamber, substantially at an angle between 60° and 120°.

23. The pelletizing apparatus according to claim 19, wherein the melt outlets of the die plate assembly are arranged in such a way that granulate particles and the water / gas mixture move towards each other at least partially inside the cutting chamber, substantially an angle of about 90°.

24. The pelletizing apparatus according to claim 13, wherein a water / granulate discharge channel for discharging the granulate mixture and / or water mixture is arranged on an upper section of the cutting chamber.

25. The pelletizing apparatus according to claim 13, wherein a water / granulate discharge channel for discharging the granulate mixture and / or water mixture is arranged on an upper section of the cutting chamber that is in a form of a pipe.

26. The pelletizing apparatus according to claim 13, wherein a water / granulate discharge channel for discharging the granulate mixture and / or water mixture is arranged on an upper section of the cutting chamber that is in a form of a pipe and is arranged substantially vertically in sections at least in order to discharge the granulate mixture, water mixture, and / or gas mixture during operation.

27. The pelletizing apparatus according to claim 14, wherein the gas nozzle arrangement is in a form of a ring nozzle.

28. An underwater pelletizing method for producing granulate from free-flowing curable plastic using the pelletizing apparatus according to claim 13, in which: liquid plastic in a form of a melt is fed to a die plate assembly having a die plate and is discharged in a form of a plurality of melt strands from the die plate through a plurality of flow channels in the die plate, the discharged melt strands are divided into separate granulate particles by means of a cutting device,the granulate particles are discharged into a cutting chamber filled with water or some other liquid, water or some other liquid is introduced into cutting chamber through at least one inlet, and water or some other liquid and granulate is conveyed out of the cutting chamber through at least one outlet, wherein gas is introduced into the cutting chamber through a gas inlet in such a way that the gas interacts with granulate particles inside the cutting chamber filled with water or other liquid.

29. The underwater pelletizing method according to claim 28, wherein gas is fed through the gas inlet to a gas nozzle arrangement connected thereto and having a plurality of nozzle orifices, and wherein the gas is discharged from the nozzle orifices into the cutting chamber to form a large number of gas bubbles inside the cutting chamber or inside a feed channel connected to the cutting chamber, and the gas bubbles interact in the cutting chamber with the granulate particles and thus affect a shape of the granulates or particles when they solidify.

30. The underwater pelletizing method according to claim 28, wherein gas is introduced through a nozzle arrangement downstream from the inlet in a region where water is fed in.31 . The underwater pelletizing method according to claim 28, wherein gas is introduced through a nozzle arrangement downstream from the inlet in a region where water is fed in, wherein a gas nozzle arrangement is arranged below the die plate assembly.

32. The underwater pelletizing method according to claim 28, wherein gas is introduced by means of a gas nozzle arrangement into a feed pipe forming the feed channel.

33. The underwater pelletizing method according to claim 28, wherein gas is introduced by means of a gas nozzle arrangement into a feed pipe forming the feed channel, which is substantially vertical in orientation.

34. The underwater pelletizing method according to claim 28, wherein gas is introduced by means of a gas nozzle arrangement into a feed pipe forming the feed channel, which is substantially vertical in orientation and arranged substantially below the die plate assembly and in operation feeds a water / gas mixture to the cutting chamber.

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