Device for supplying plastic and method for metering out plastic

Abstract

The present invention relates to an apparatus (1) and a method for providing a plastic (2) formed from a component A (3) and a component B (4) and optionally formed from a first additive (6). The apparatus (1) has a mixing chamber (70) in which the component A (3) and the component B (4) are mixed to form the plastic (2) and the plastic (2) is metered out, and an additional valve unit (30) fluidly arranged upstream of an A inlet (71) of the mixing chamber (70) for the component A (3). The additional valve unit (30) has a main pipe (31) for supplying the component A (3) to the A inlet (71) and a first additional injection valve (33) for supplying the first additive (6) to the main pipe (31). The first additional injection valve (33) has an outlet nozzle (36) opening into the main pipe (31). The nozzle tip (37) of the outlet nozzle (36) is located in the central region of the flow cross-section of the main pipe (31), and the point of the flow cross-section located inside the inner part of the radial connection line between the cross-section center and the inner wall of the main pipe (31) is located in the central region, and the length of the inner part is 90% of the radial connection line.

Description

Technical Field

[0001] The present invention relates to an apparatus for supplying plastics that can be produced from component A, component B, and optionally a first additive. The present invention also relates to a method for metering out plastics.

[0002] German Utility Model No. 202005020930 discloses an apparatus in which a polyol is used as component A and an isocyanate is used as component B in the production of polyurethane. This apparatus has a container in which the polyol is stored. Further, this apparatus has a first supply source for a first additive in the form of a first colorant. Further, this apparatus has a second supply source for a second additive (second colorant). In the mixing chamber, the polyol component and the isocyanate component are mixed to form polyurethane. The polyurethane is metered out from this mixing chamber and sprayed onto a substrate to be coated, forming a polyurethane surface.

[0003] An additional valve unit or a color valve unit is connected upstream of the A inlet or the polyol inlet of the mixing chamber with respect to the flow. Upstream, there are premixing chambers for each individual colorant, where the polyol and the colorant are mixed. Each premixing chamber is assigned a pump that feeds the corresponding colored polyol to the additional valve unit via a color-separated supply line. Further, a circulation line and a circulation valve for returning unused material to the corresponding premixing chamber are provided for each color. The line extends from the additional valve unit to the polyol inlet of the mixing chamber. Thus, this apparatus makes it possible to supply plastics with different properties, i.e., different colors in this case. The structure of the apparatus disclosed in German Utility Model No. 202005020930 is relatively complex.

[0004] U.S. Patent Application Publication No. 2007 / 0145641 discloses an apparatus for supplying colored polyurethane. In this apparatus, a polyol source, an isocyanate source, and supply lines from two additional sources open into a mixing chamber. These supply lines store, on the one hand, a mixture of polyol and blowing agent and, on the other hand, a mixture of polyol and coloring agent. Due to the multiple inlets, the mixing chamber has a complex structure. Furthermore, only the colored polyol can be introduced into the mixing chamber, and it is expected to be very time-consuming to remove the previous coloring agent from the apparatus before using another coloring agent.

[0005] Accordingly, an object of the present invention is to provide an apparatus for supplying plastic that has a simple structure and can be operated without great effort even when the properties of the plastic change.

[0006] The object to be solved by the present invention is achieved by the combination of features according to claim 1. Embodiments of the present invention are described in the dependent claims of claim 1.

[0007] According to the present invention, the additional valve unit has a main pipe for supplying component A to inlet A and a first additional injection valve for supplying a first additive to the main pipe. The first additional injection valve has an outlet nozzle that opens into the main pipe, and the nozzle tip of the outlet nozzle is located in the central region of the flow cross-section of the main pipe. The central region of the flow cross-section includes all points of the flow cross-section that are located inside the inner part of the radial connection line between the cross-section center and the inner wall of the main pipe, and the length of the inner part is 90% of the radial connection line.

[0008] In one embodiment, the flow cross-section of the main pipe is circular, and the radial connection line corresponds to the radius R of the circle. According to the present invention, the nozzle tip of the outlet nozzle is located within a central circle having a radius R corresponding to 90% of the radius R. m

[0009] ​The inner diameter of the round main pipe may be from 4 mm to 10 mm. When the inner diameter is, for example, 6 mm, the radius R is half, that is, 3 mm. The radius R m is 2.7 mm. According to the present invention, the nozzle tip is located within the middle circle with a radius R m = 2.7 mm.

[0010] The flow cross-section of the main pipe may be elliptical or polygonal, for example, rectangular. The cross-section center of the rectangular flow cross-section is located at the intersection of the diagonals of the rectangular flow cross-section. The central region where the nozzle tip of the outlet nozzle is located is delimited by a central rectangle whose cross-section center coincides with the cross-section center of the flow cross-section. The length of the side of the intermediate rectangle is 90% of the length of the side of the rectangular flow cross-section.

[0011] For the arrangement according to the present invention of the nozzle tip of the outlet nozzle of the first additional injection valve in the intermediate region of the flow cross-section, the first additive is introduced into the main flow of component A flowing through the main pipe and can thus be carried along with component A. In this way, contact between the first additive and the inner wall of the main pipe can be prevented. This has the advantage that the first additive does not precipitate on the inner wall of the main pipe. The precipitation of the first additive on the inner wall of the main pipe can lead to carry-over if the plastic is no longer intended to contain the first additive and thus to change its properties. For example, the first additive may be a first colorant that colors the white plastic.

[0012] Therefore, component A corresponds to a coating for the first additive, thereby preventing or at least significantly reducing direct contact between the additive and the inner wall of the main pipe. This has the advantage that a plastic with properties immediately changed when the additive is stopped is obtained. The new plastic, that is, the plastic that does not contain the previously used additive, contains no or only a small amount of the previously used additive during the transition phase. If the additive is a colorant, streaks of color appear in the new plastic, that is, white or transparent plastic, for a short time and to a small extent.

[0013] The length of the inner portion of the connecting line passing through the plane of the flow cross-section between the cross-section center and the inner wall of the main pipe may be only 70% or 50% of the length of the radial connecting line. In an embodiment with a circular flow cross-section, the radius R of the inner circle (inner region) m is 70% (or 50%) of the radius R of the flow cross-section.

[0014] In one embodiment, the main pipe is linear and at least linear in the region where at least the color injection valve opens into the main pipe. Preferably, the main pipe extends substantially vertically so that the A component can flow from top to bottom through the main pipe. In one embodiment, the main pipe extends strictly vertically.

[0015] To make the additional valve unit compact, the central axis of the first additional injection valve may be arranged substantially perpendicular to the central axis of the main pipe. In the case of a vertical main pipe, this means that the central axis extends in a horizontal plane.

[0016] The additional valve unit may comprise a plurality of additional injection valves, for example 4 to 10 additional injection valves. In one embodiment, 7 additional injection valves are provided. Thus, the additional valve unit may have at least a second additional injection valve that serves to supply a second additive. If the additives are each a coloring agent, the apparatus according to the present invention can be used to produce plastics of different colors. The additive may be a catalyst or the like.

[0017] The central axis of the second additional injection valve and the central axes of further additional injection valves may extend substantially perpendicular to the central axis of the main pipe. In one embodiment, the central axes of all the additional injection valves are perpendicular to the central axis of the main pipe.

[0018] The first additional injection valve and the second additional injection valve may be arranged one behind the other when viewed in the longitudinal direction range of the main pipe. In other words, the additional injection valves may be connected in series when viewed in the flow direction.

[0019] The central axis of the first additional injection valve may be offset from the central axis of the second additional injection valve when viewed in the circumferential direction of the main pipe. Thereby, a plurality of additional injection valves can be accommodated even in a relatively short main pipe. The arrangement of the additional injection valves may be selected such that all the additional injection valves are arranged only in a circumferential region smaller than 180° (for example, only in one quadrant (meaning an angular region of 90°)). Thereby, flexible response to a given limited space becomes possible.

[0020] The first additional injection valve may include a needle valve and a gear pump. In this case, the central axis of the additional injection valve coincides with the central axis of the needle of the needle valve. The needle valve and the gear pump may be accommodated in a common housing or in separate housings. The needle valve and the gear pump are fluidly connected to each other such that the pressure generated by the gear pump acts on the needle valve. The first additional injection valve may be designed as an eccentric screw pump. The pump and valve components are combined in one design.

[0021] The above and below descriptions regarding the design and arrangement of the first additional injection valve are similarly applicable to other additional injection valves. Preferably, all the additional injection valves used in the additional valve unit have the same structure.

[0022] The device may comprise an A metering valve for controlling or regulating the flow rate of component A into the mixing chamber. The A metering valve may be arranged between the main pipe and the A inlet of the mixing chamber. In one embodiment, the main pipe extends substantially perpendicular to the central axis of the A metering valve, and component A enters the A metering valve from a side inlet. The inlet and outlet of the metering valve may be substantially perpendicular to each other. That is, within the A metering valve, component A makes a directional change of about 90° or exactly 90° together with the first additive (or another additive) therein. This directional change causes the additive protected by component A in the main pipe to come into contact with the inner wall of the A metering valve, and the additive may settle in areas of the A metering valve that are not sufficiently covered by the main flow through the A metering valve. This is accompanied by deposits when the additive is exchanged and the corresponding risk of carry-over or contamination.

[0023] To avoid, as much as possible, one undesirable deposition of the additive in the A metering valve, the nozzle tip of the first additional injection valve is preferably arranged between the cross-sectional center of the main pipe and the longitudinal half on the outlet side of the main pipe. Such an arrangement of the nozzle tip has been shown to improve the transport of the additive through the A metering valve, particularly in the part of the valve where a 90° directional change takes place.

[0024] The cross-section of the outlet nozzle of the first additional injection valve may be circular, elliptical, or teardrop-shaped. An outlet nozzle protruding into the flow cross-section would be an obstacle to the flow of component A through the main pipe. With an outlet nozzle cross-section optimized for the flow with the smallest possible flow resistance for component A, there is no sharp directional change in the vicinity of the color injection site that would promote the mixing of component A and the first additive. However, according to the present invention, good mixing within the main pipe is not desired regardless of the specific design of the cross-section of the outlet nozzle. Rather, the first additive should be embedded in the main flow of component A, and contact between the additive and the inner wall of the main pipe should be avoided. The intense mixing of the first additive with component A (and component B) takes place only within the mixing chamber. The mixing chamber may be a static mixer.

[0025] The outlet nozzle can have various shapes. In one embodiment, it is linear and extends coaxially with the central plane of the first additional injection valve. In an embodiment where the central plane of the first additional injection valve is perpendicular to the central axis of the main pipe, the first additive is injected into the A component perpendicular to the main flow direction. Alternatively, the outlet nozzle of the first additional injection valve may have an angle of about 90° such that the nozzle tip faces the longitudinal direction of the main pipe or the main flow direction. In this case, the first additive exits from the nozzle tip in the direction of the main flow of the A component. Also, an inclination angle between 20 and 70° may be provided between the (linear) outlet nozzle and the central axis of the first additional injection valve.

[0026] A further object of the present invention, which provides a method for metering out plastic, is achieved by the combination of features according to claim 13.

[0027] Embodiments of the method according to the present invention may be described in the claims dependent on claim 13.

[0028] According to the present invention, the device described herein, in particular the device according to any one of claims 1 to 12, is used in a metering method, and the first additional injection valve is controlled such that after the first additive is metered out, a small portion of the A component is drawn into the outlet nozzle of the first additional injection valve. In the next metering step, this drawn-in portion of the A component is returned to the main pipe.

[0029] In one embodiment of the method according to the present invention, an apparatus having a plurality of additional injection valves is used. When viewed in the flow direction of the main pipe, the first additional injection valve is arranged upstream of the second additional injection valve, and the first additive formed as a coloring agent is lighter than the second additive formed as a coloring agent. When there are a plurality of additional injection valves, they may be arranged in order in the flow direction according to the lightness of the additives (coloring agents) to be injected. The additional injection valve with the lightest additive is the farthest from the A metering valve. The RGB model may be used to determine the brightness of the additive. The RGB model is an additive color mixing model, and the color becomes brighter as the colors are mixed.

[0030] Between the metering through the first additional injection valve and the metering through the second additional injection valve, the following procedure may be used for rinsing regardless of whether the additive is a coloring agent or not. First, the metering through the first additional injection valve is stopped, and the A component continues to flow through the main pipe. Then, the first additional injection valve is controlled to draw back a part of the first additive and, if necessary, draw out a part of the A component from the main pipe. Then, the first additional injection valve is closed.

[0031] Subsequently, metering is carried out from the second additional injection valve. The metering of the second additive is started and continued until the concentration of the first additive in the A metering valve becomes substantially zero (the ratio of the first additive to the A component, for example, less than 0.1%). Then, the mixing chamber is rinsed with a cleaning agent, and the last color residue of the first additive is removed from the mixing chamber. After rinsing, the metering of the second color is started again.

[0032] A preferred use of the present apparatus and method is to supply polyurethanes of different colors, where the A component is a polyol and the B component is an isocyanate. The viscosity of the polyol is in the range of 50 to 1,000,000 mPas, preferably 1,000 to 100,000 mPas. The viscosity of the isocyanate is 10 to 100,000, preferably 50 to 5,000 mPas. The A component and the B component may be other substances, such as silicone, epoxy, and MS polymer.

[0033] The viscosity of the first additive (and other additives) may be from 10 to 100,000 mPas. In one embodiment, the viscosities of the first additive and the second additive are each from 200 to 10,000 mPas.

[0034] The total discharge at the outlet of the mixing chamber may be from 0.2 to 150 g / s, preferably from 3 to 30 g / s. The mixing ratio of component A and component B may be from 10:1 to 1:10. When producing polyurethane, the mixing ratio of polyurethane and isocyanate is preferably between 1:1 and 10:1. The ratio of the total discharge of the additives used in each case may be from 0.5 to 20%, preferably from 1 to 5%.

[0035] It should be noted that two or more additional injection valves can meter corresponding additives into the main pipe simultaneously. When the additive is a coloring agent, the plastic is colored by the mixed coloring agent. Thereby, for example, in the case of five additional injection valves, it becomes possible to supply five or more colors to the plastic.

[0036] The present invention will be described in more detail with reference to the embodiments shown in the figures.

Brief Description of the Drawings

[0037]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Best Mode for Carrying Out the Invention

[0038] FIG. 1 shows an apparatus generally designated by the numeral 1. The apparatus 1 can be used for the production and metering of plastic 2. The plastic 2 is a multi-component plastic consisting of component A 3 and component B 4. In this case, the multi-component plastic is intended to be polyurethane, and component A is a transparent polyol. Component B is an isocyanate. It is also possible to use a white polyol instead of the transparent polyol.

[0039] Component A or polyol 3 is stored in an A supply source 10 designed as a pressure vessel. The pressure vessel 10 is filled with compressed air 5. Component A 3 is circulated by a pre-circulation pump 11. A pressure control valve 12 is installed in the circuit to control the pressure of the pre-circulation circuit. The pre-circulation pump 11 preferably operates continuously at a constant speed.

[0040] Component A 3 is supplied to an A metering pump 13 via the pressure of the pre-circulation circuit. The A metering pump 13 supplies component A to an additional valve unit 30 delimited by a dashed rectangle in the view of FIG. 1. The first additive 6, the second additive 7, or the third additive 8 is supplied to component A 3 by the additional valve unit 30. Additives 6-8 are examples of a plurality of different additives. For example, seven types of additives may be provided.

[0041] The additives may be various colorants. It is possible for the additional valve unit 30 to simultaneously add the first additive (colorant) 6 and the second additive (colorant) 7 to component A 3 and color the plastic 2 in the corresponding mixed color. The first additive 6 is supplied, for example, from a first additional supply source 14 which may be a container. The second additive 7 and the third additive 8 are supplied from a second additional supply source 15 and a third additional supply source 16, respectively. An embodiment of the additional valve unit 30 can be seen in FIG. 2, which will be described in detail later.

[0042] Downstream of the additional valve unit 30 as seen in the flow direction, a metering valve 17 for component A3 (abbreviated as A metering valve 17) is provided, and a mixture of component A3 and the additive is discharged into the mixing chamber 70 using this valve. The A metering valve 17 should be arranged immediately upstream of the A inlet 71 of the mixing chamber 70.

[0043] The mixing chamber 70 is provided with a further inlet 72 (B inlet) for component B4. Component B4 is supplied from a B supply source 18 (designed as a container in this specification) and is supplied to the mixing chamber 70 via a B metering pump 19 and a B metering valve 20. In the mixing chamber 70, component B4 and component A3 containing one of the additives 6, 7, 8 or a mixture of the additives 6, 7, 8 are vigorously mixed with each other to form a colored multi-component plastic 2. Depending on the additive added to component A3 in the additional valve unit 30, the plastic 2 has different properties. Therefore, if the additive is formed as a coloring agent, plastics 2 of different colors can be supplied by the apparatus 1.

[0044] Figure 2 shows an embodiment of the additional valve unit 30. The additional valve unit 30 includes a main pipe 31 having a circular flow cross-section. The main pipe 31 opens into the side inlet 21 of the A metering valve 17. The A metering valve 17 is formed as a needle valve having a needle 22 arranged movably along the central axis 23 of the A metering valve 17. The needle 22 enables the opening and closing of the outlet 24 of the A metering valve 17. The outlet 24 may be connected to the A inlet of the mixing chamber 70 without the need for an intermediate line or other components (such as pumps, valves, etc.). The central axis 32 of the main pipe 31 coincides with the central axis 27 of the side inlet 21. The central axis 32 of the main pipe 31 and the central axis 23 of the A metering valve 17 are perpendicular to each other.

[0045] The needle 22 is disposed within a cylindrical valve chamber 25 that is fluidly connected to the side inlet 21. An annular or hollow cylindrical cavity is formed between the needle 22 and the inner wall of the valve chamber 25, through which the component A 3 flows together with the first additive 6. At the lower end 26 on the inlet side of the valve chamber 25, on the side opposite to the opening of the side inlet 21, it has been found that the flow through the A metering valve is relatively weak. Therefore, in the component A 3, color residues may mainly gather and deposit at the lower end 26.

[0046] The component A 3 is supplied vertically from above to the main pipe 31. The component A 3 flows through the main pipe 31 and reaches the A metering valve 17 through the inlet 21. The volumetric flow rate of the component A 3 from the outlet 24 to the mixing chamber 70 can be controlled via the axial position of the needle 22.

[0047] The structure of the needle valve is known in principle. The details or components of the needle valve covered by the white ellipse are not particularly related to the present invention. This also applies to other needle valves shown in FIG. 2. There too, details not related to the present invention are covered by the white ellipse.

[0048] As can also be seen from FIG. 2, a first additional injection valve 33 comprising a needle valve 34 and a gear pump (not shown in FIG. 2) opens into the main pipe 31. The first additional injection valve 33 is also schematically shown in FIG. 1. The gear pump is provided with the reference numeral 35 in FIG. 1.

[0049] The needle valve 34 of the first additional injection valve 33 or the additional injection valve 33 has an outlet nozzle 36 having a nozzle tip 37. The outlet nozzle 36 of the additional injection valve 33 projects into the main pipe 31. Therefore, the first additional injection valve 33 can be used to introduce the first additive 6 (see FIG. 1) into the main pipe 31. The pressure at which the first additive 6 is introduced into the flow of the component A is such that the first additive 6 is enveloped by the flow of the component A and is carried along with the component A without intense mixing of the component A 3 and the first additive 6 occurring.

[0050] Without being bound by this theory, a separation boundary layer is formed between the component A 3 and the injected additive 6, thereby preventing the first additive 6 from contacting the inner wall of the vertical main pipe 31. In order for the component A 3 to be able to perform the above-described surrounding function, according to the present invention, it is provided that the nozzle tip 37 of the outlet nozzle 36 is located in the central region of the flow cross-section of the main pipe 31. Then, the first additive 6 can be completely confined within the main pipe. If the outlet nozzle 36 directly terminates at the inner wall of the main pipe, there is a risk that the first additive 6 wets the inner wall and adheres thereto.

[0051] The central axis 38 of the needle valve 34 is intended to represent the central axis of the first additional injection valve 33 and is perpendicular to the central axis 32 of the main pipe. The needle 39 is arranged to be movable along the central axis 38, whereby the flow rate through the needle valve 34 can be adjusted.

[0052] In FIG. 2, in addition to the first additional injection valve 33, a second additional injection valve 40 and a third additional injection valve 41 having the same structure as the first additional injection valve 33 are shown. Due to the same structure, the same reference numerals are assigned to the features or components of the additional injection valves 40 and 41 that are the same as the features or components of the first additional injection valve 33. In particular, these additional injection valves 40 and 41 each also include an outlet nozzle 36 having a nozzle tip 37. The outlet nozzle 36 of the second additional injection valve 40 and the outlet nozzle 36 of the third additional injection valve 41 both project into the main pipe 31. The second additional injection valve 40 serves to introduce the second additive 7 (see also FIG. 1) into the flow of the component A 3. The third additive 8 can be injected into the main pipe 31 through the third additional injection valve 41.

[0053] While the central axis 38 of the first additional injection valve 33 and the central axis 38 of the third additional injection valve 41 are located in the drawing plane, the second additional injection valve 40 is inclined with respect to the drawing plane.

[0054] Figure 3 is a schematic diagram showing the cutouts of the main pipe 31 and the additional injection valves 33, 40, 41. The outlet nozzle 36 of the first additional injection valve 33 is linear and extends along the central axis 38 of the first additional injection valve 33. It can be seen that the nozzle tip 37 is located very close to the central axis 32 of the main pipe 31.

[0055] Figure 4 showing a cross-section along line IV-IV of Figure 3 shows the circular flow cross-section of the main pipe 31. The flow cross-section is defined by a radius R, which can be understood as the connecting line between the center of the cross-section and the inner wall of the main pipe 31. The center of the cross-section is located on the central axis 32. The nozzle tip 37 is located in the central region limited by the dashed circle 42 having a radius R m According to the present invention, the relationship of R m / R is 0.9. According to the present invention, points outside the circle 42 do not belong to the central region. In one embodiment, the relationship of R m / R is only 0.5, which approximately corresponds to the relationship in Figure 4.

[0056] Compared with the first additional injection valve 33, the second additional injection valve 40 has an improved outlet nozzle 43. The nozzle tip of the improved outlet nozzle 43 is indicated by 44 and is located in the central region of the flow cross-section of the main pipe 31, similar to the nozzle tip 37 of the first additional injection valve 33. The outlet nozzle 43 has an angle of 90° such that the second additive 7 introduced into the main pipe 31 through the second additional injection valve 40 passes through the nozzle tip 44 in the flow direction of the main pipe 31. The third additional injection valve 41 has an outlet nozzle 45 inclined with respect to the central axis 38. The inclination angle between the outlet nozzle 45 and the central axis 38 is indicated by α in Figure 3 and is about 40° to 50° in the illustrated embodiment. Here too, the nozzle tip 46 of the inclined outlet nozzle 45 is located in the central region of the flow cross-section of the main pipe 31.

[0057] FIG. 5 shows various cross-sections of the outlet nozzle 36 of the first additional injection valve 33. The cross-section of the outlet nozzle 36 corresponds to the cross-section along line V-V in FIG. 3. FIG. 5A shows a circular cross-section of the outlet nozzle 36. FIG. 5B shows a rectangular cross-section of the outlet nozzle 36. The cross-section of the outlet nozzle 37 can be optimized to achieve a small flow resistance caused by the outlet nozzle 36 protruding into the main pipe 31, for example, by an elliptical cross-section (see FIG. 5C) or a teardrop shape of the outlet nozzle 36.

[0058] FIGS. 3 to 5 show various embodiments of the outlet nozzles of the additional injection valves 33, 40, 41. For example, it goes without saying that all the additional injection valves 33, 40, 41 can have the structure shown as an example for the first additional injection valve 33 in FIG. 3. Further, all the additional injection valves 30, 40, 41 or a subgroup thereof may have an angled outlet nozzle 43 or an inclined outlet nozzle 45.

[0059] FIGS. 1 and 2 are intended to be used to explain the so-called color change in the apparatus 1. Assume that the first additional injection valve 33 injects the first additive (colorant) 6 into the main pipe 31 while the flow of the A component through the main pipe 31 is constant. The A component 3 encloses the first additive 6 exiting from the outlet nozzle 36. The A component flows through the A metering valve 17 together with the first additive 6. In the mixing chamber 70, the A component 3 is mixed with the first colorant 6 and the B component 4. The plastic 2 colored by the first colorant 6 is metered out.

[0060] After the plastic 2 colored by the first colorant 6 is metered out, the plastic 2 colored by the second additive (colorant) 7 is metered out. For this purpose, the first additional injection valve 33 is closed, or alternatively, the gear pump 35 is rotated in reverse to operate so as to draw back the colorant 6 and / or a small portion of the A component that has already been metered out immediately before to the needle valve 34. After closing or operating the first additional injection valve 33 in reverse, the second additional injection valve 40 is opened, and the second colorant 7 is introduced into the flow of the A component 3. Due to the arrangement of the nozzle tip 37 according to the present invention, there is no area in the main pipe 31 or in the valve chamber 25 of the A metering valve 17 where the previously metered first colorant 6 accumulates or deposits. In particular, when the nozzle tip 37 is located in the half of the central region facing the outlet 24 of the A metering valve 17 (in the figure of FIG. 2, this is the half of the central region on the left side of the central axis 32), there is substantially no significant color residue at the lower end 26 of the valve chamber 25 that makes color change difficult or delays it. After a relatively short time since the second colorant 7 starts to be metered out, streaks or contamination due to the color residue of the first colorant 6 are no longer visible in the plastic 2. Thus, the device 1 according to the present invention can achieve color change between different colorants 6, 7, 8 without much effort. Therefore, the period during which the plastic 2 shows contamination due to color change can be shortened. Also, the labor required for flushing during color change can be minimized.

Explanation of Signs

[0061] 1 Device 2 Plastic 3 A Component 4 B Component 5 Air 6 First Additive / First Colorant 7 Second Additive / Second Colorant 8 Third Additive / Third Colorant 10 A Supply Source / Pressure Vessel 11 Pre - circulation Pump 12 Pressure Control Valve 13 A Metering Pump 14 First Additional Supply Source 15 Second Additional Supply Source 16 The 3rd additional supply source 17 A metering valve 18 B supply source 19 B metering pump 20 B metering valve 21 Side entrance 22 Needle 23 Central axis 24 Outlet 25 Valve chamber 26 Lower end 27 Central axis 30 Additional valve unit 31 Main pipe 32 Central axis 33 The 1st additional injection valve 34 Needle valve 35 Gear pump 36 Outlet nozzle 37 Nozzle tip 38 Central axis 39 Needle 40 The 2nd additional injection valve 41 The 3rd additional injection valve 42 Circle 43 Outlet nozzle 44 Nozzle tip 45 Outlet nozzle 46 Nozzle tip 70 Mixing chamber 71 A inlet 72 B inlet

Claims

1. A device (1) for supplying a plastic (2) formed from component A (3) and component B (4), and optionally a first additive (6), The aforementioned device (1) is The aforementioned component A (3) and component B (4) are mixed to form the plastic (2), and a mixing chamber (70) is used to weigh and dispense the plastic (2), An additional valve unit (30) is fluidly positioned upstream of the A inlet (71) of the mixing chamber (70) for component A (3), and Equipped with, The additional valve unit (30) includes a main pipe (31) for supplying component A (3) to the A inlet (71) and a first additional injection valve (33) for supplying the first additive (6) to the main pipe (31). The first additional injection valve (33) has an outlet nozzle (36) that opens into the main pipe (31), The nozzle tip (37) of the outlet nozzle (36) is located in the central region of the flow cross-section of the main pipe (31), The point of the flow cross section located in the inner portion of the radial connection line between the center point of the cross section and the inner wall of the main pipe (31) is located in the central region, Apparatus (1), wherein the length of the inner portion is 90% of the radial connection line.

2. The apparatus (1) according to claim 1, wherein the flow cross-section of the main pipe (31) is circular, and the radial connection line corresponds to the radius (R) of the circle.

3. The apparatus (1) according to claim 1 or 2, wherein the main pipe (31) extends substantially vertically.

4. The apparatus (1) according to claim 1 or 2, wherein the central axis (38) of the first additional injection valve (33) is positioned substantially perpendicular to the central axis (32) of the main pipe (31).

5. At least a second additional injection valve (40) is provided to supply the second additive. The apparatus (1) according to claim 1 or 2, wherein the second additional injection valve (40) has an outlet nozzle (36) that opens into the main pipe (31), and the tip of the nozzle (37) is located in the central region of the flow cross-section of the main pipe (31).

6. The apparatus (1) according to claim 5, wherein the first additional injection valve (33) and the second additional injection valve (40) are arranged sequentially with respect to each other within the longitudinal range of the main pipe (31).

7. The apparatus (1) according to claim 5, wherein, when viewed in the circumferential direction of the main pipe (31), the central axis (38) of the first additional injection valve (33) is offset from the central axis (38) of the second additional injection valve (40).

8. The apparatus (1) according to claim 1 or 2, wherein a metering valve A is provided, the main pipe (31) extends substantially perpendicular to the central axis (23) of the metering valve A (17), and component A (3) enters the metering valve A (17) from the side inlet (21).

9. The apparatus (1) according to claim 8, wherein the A metering valve (17) has an outlet (24), and the nozzle tip (37) of the first additional injection valve (33) is located between the center of the cross-section and the outlet-side longitudinal half of the main pipe (31).

10. The apparatus (1) according to claim 1 or 2, wherein the cross-section of the outlet nozzle (36) of the first additional injection valve (33) is circular, elliptical, or teardrop-shaped.

11. The apparatus (1) according to claim 1 or 2, wherein the outlet nozzle (36) of the first additional injection valve (33) has an angle of approximately 90°, and the nozzle tip (37) is oriented in the longitudinal direction of the main pipe (31).

12. The apparatus (1) according to claim 1 or 2, wherein an inclination angle between 20° and 70° is provided between the outlet nozzle (36) and the central axis (38) of the first additional injection valve (33).

13. A method for weighing and dispensing plastic (2) using the apparatus (1) according to claim 1 or 2, wherein the first additional injection valve (33) is controlled such that, after the weighing and dispensing step, a small portion of component A (3) is drawn into the outlet nozzle (36) of the first additional injection valve (33).

14. A method according to claim 13 using the apparatus (1) described in claim 5, When viewed in the flow direction of the main pipe (31), the first additional injection valve (33) is located upstream of the second additional injection valve (40), and the first additive (6) is formed as the first coloring agent (6) and is lighter than the second additive (7) which is formed as the second coloring agent (7), by

15. Between the dispensing through the first additional injection valve (33) and the dispensing through the second additional injection valve (40), the following steps are taken for rinsing purposes: The metering and dispensing through the first additional injection valve (33) is stopped, and component A (3) continues to flow. The first additional injection valve (40) is controlled to pull back and close a portion of the first additive (6), Metering is initiated and continued through the second additional injection valve (40) until the concentration of the first additive (6) in the A metering valve (17) becomes substantially zero. The mixing chamber (70) is rinsed with a cleaning agent. After rinsing, the dispensing of the second additive (7) is restarted. The method according to claim 14, wherein the action is initiated.

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