RU2268144C2 - Method and a device for junction of streams of materials in the process of a joint extrusion - Google Patents

Abstract

FIELD: chemical industry; food industry; methods and devices for junction of streams of materials during a joint extrusion.

SUBSTANCE: the invention is pertaining to the method and the device for junction of streams of materials during a joint extrusion of materials, for example, thermoplastic polymeric compounds, inorganic pastes and some sorts of foodstuff. In the indicated method a material "B" is extruded on a material "A" through a hole. At that the separating wall between the streams of materials "A" and "B" is made in the form of a shutting valve operating in the capacity of a reverse valve for the stream of the material "B" being extruded on the material "A". Extrusion of the material "B" through the hole is conducted in a pulsing mode. Pulsations may be caused by opening and closing the shutting valve, or by a means of a mechanical pulses transmitting gear, or due to production of differences of the pressures acting on the valve from the streams of the material "A" and-or material "B". The invention also presents the extruding machine for realization of the method (versions). The invention allows to distribute uniformly the material "B" with a low viscosity at its extrusion on the material "A" with a higher viscosity, ensures production of sheets or pipes with interleaving sections with various pliability or a coextrusion of a stream of solid particles with a stream of a fluid material.

EFFECT: the invention ensures the uniform distribution of the material "B" with a low viscosity at its extrusion on the material "A" with a higher viscosity and production of sheets or pipes with interleaving sections with various pliability or a coextrusion of a stream of solid particles with a stream of a fluid material.

47 cl, 12 dwg

Description

The invention relates to a method for co-extrusion of the type defined in the restrictive part of paragraph 1 of the claims, and to a device for implementing this method. The method is applicable for extrusion of essentially all materials that can be extruded, for example, such as thermoplastic polymers, inorganic pastes, for example, for molding ceramic materials and some types of food products.

The invention has three different aspects related to three different objectives. The first aspect relates to the use of coextrusion to coat, on one or both sides, the extrudable material A, which during the extrusion process has a high specific viscosity, with a thin layer or thin layers of material B having a significantly lower specific viscosity. In such cases, the coating usually becomes very uneven or may even be absent on part of the surface using conventional technology, since the energy required to make the flow of material B evenly distributed in the form of a thin stream, more energy is needed to force the material In flow in the form of narrow jets of greater thickness.

A second aspect of the invention relates to co-extrusion of sheets or pipes in which portions of one component alternate with portions of another component, with alternation taking place along the direction of extrusion. As an important example of such an aspect, a pipe can be given in which rigid sections alternate with flexible sections (in this case, the product has relative stiffness).

Another third aspect of the invention relates to the co-extrusion of a stream of solid, substantially dry particles with a stream of truly fluid material such that the stream of solid particles absorbs the fluid material (i.e., the fluid material is mixed with the solid particles).

An important example of the implementation of this aspect is the method of mixing Teflon particles (polytetrafluoroethylene - PTFE) with molten liquid polyamide and extruding sheets, tapes or pipes from the mixture. In addition, this aspect of the invention can be used in the manufacture of special ceramic products, especially porous products, by a method in which solid inorganic particles, for example containing short reinforcing fibers, are mixed with a prepolymer, which subsequently cures, or with an aqueous solution or dispersion of an inorganic material, which after drying and heat treatment will act as a binder. Similarly, a third aspect of the invention can be used in co-extrusion of a belt of median material that can be pulverized to tablets.

U.S. Pat. that in the patents issued in the name of Cloeren, it is called the “curling effect”, that is, the formation of some profile of a co-extruded film, which has the form of a pattern with a length along the transverse axis, formed at the place where the two streams from which the sheets form are connected with each other, if these flows have different rheological properties, and especially also in the case of their joint cracking in approximately equal amounts. These four patents provide for the use of one or more dampers that can be rotated and which end where the flows are connected to each other. In the first three patents, means are provided for adjusting the dampers so that the ratio between the flow rates at the place where they are connected corresponds to the rheological properties and output of the components. The last mentioned patent provides for the use of one or more freely rotating, pivotally mounted rotary shutters, which provide automatic adaptation to various rheological properties and output of the components, namely in such a way that the pressure becomes the same on both sides of the shutter. The "effect of the will", which these four patents are aimed at, represents a problem that differs from the problem that is addressed by the first aspect of the present invention (see above) and which is associated with the formation of stripes not in the transverse, but in the longitudinal direction. It was found during experiments that the measures disclosed in the four patents mentioned do not solve this problem.

US Pat. No. 4,469,475 to Krysiak discloses an extruder suitable for the manufacture of food products containing a core and a shell. The extruder comprises a closure element which is designed to prevent the material forming the sheath from entering the channel through which the filling is extruded. The closing element is located close to the exit of the extruder.

International publication WO-A-0060959 describes an extruder and process that are within the scope of the claims of this application. The above invention is entitled to priority from the filing date of the relevant PCT application, on the basis of which this application claims priority. Therefore, the method and apparatus disclosed in this international publication do not represent the prior art with respect to the present invention.

Each of the three different goals is achieved by essentially the same means, namely, by developing a new method for co-extrusion of a stream of extrudable material A with a stream of extrudable material B in the joint zone in the head for co-extrusion (this term covers the adapter located in front of the forming head to obtain the final product), in which the extrusion of material B onto material A occurs through the hole (3), and two materials pass together through the channel (7) towards the exit (8) wafer, the dividing wall between the flows immediately before its end in the hole (3) is made in the form of a closing flap (4), configured to act as a check valve for the flow of material B, extruded onto material A, characterized in that the extrusion of the material (B) through the hole (3) occurs in a pulsating manner.

In accordance with the first aspect of the invention, the ripple occurs in the form of impacts to ensure uniform distribution of material B on material A along the entire length of the opening 3, and unevenness along the flow direction caused by the ripple is smoothed out, at least partially, during the joint passage of components A and B through the end of the co-extrusion die, as will be further explained below.

According to a second aspect of the invention, the method allows the closing flap (or closing flaps if material B is extruded on both sides of the material A during co-extrusion) to function as valves that stop at least substantially the flow of material A during each The “pulse” of discontinuous extrusion of material B. This aspect will also be discussed in more detail below. In accordance with a third aspect of the invention, material A is pushed using a plunger (22) located immediately in front of the junction of the flows along the course of the flow.

In the present description, the term “damper” or “closing damper” refers to an element that is rotatably mounted along one side and which can rotate about an axis of rotation, for example, under the action of a drive means or fluid pressure acting on the damper. In each of the three embodiments of the invention, the closing flap is preferably substantially flat and, as a rule, is a spring knife [blade], possibly, but not necessarily, with a thicker or harder portion at its end, located downstream ( claim 2). The spring knife can be made of steel or other suitable material and can even be made of rubber material if the extrusion temperature is low enough to allow the use of such material. A possible, but optional, thicker or harder portion at the downstream end serves to stabilize the opening and closing of the shutter and can be almost mandatory if the rubber material is selected as the material to serve as a flexible knife (hinge) . The pulsation of the flow of material B is usually best done upstream of the closing flap using one or more plungers or by opening and closing valves (claim 3). Alternatively, this ripple can be accomplished by opening and / or closing the closing flap using mechanical transmission means (claim 4). The first possible embodiment is illustrated in FIGS. 1 and 3c, and the last possible embodiment is illustrated in FIG. 4a.

In order to ensure the most ordered combination of components A and B, both of them should preferably be flat streams at least in the immediate vicinity of the part where they are combined, and should be substantially parallel to the damper at this point (claim 5).

The invention can be directly applied for co-extrusion of a flat sheet or strip from a co-extrusion slit die (claim 6), while use in an annular extrusion die may require special precautions. In such annular extrusion heads, the components usually (but not in all cases) flow essentially in the axial direction where they join, and the end of the wall that separates the components before joining them has a substantially circular cylindrical shape. For the present invention, this means that the spring knife should form a ring of a substantially cylindrical shape, and such a shape, as a rule, exhibits such a great resistance to bending that component B will be applied unevenly to component A.

This problem can be solved by manufacturing an annular closing flap with surfaces substantially perpendicular to the specified axis of the extrusion head (claim 7).

In this regard, the two components, preferably at least in the immediate vicinity of their junction, are forced to flow in a substantially radial direction (which may be an outward or inward direction with respect to the axis of the annular extrusion head), and after the flows are connected, they can be directed essentially in the axial direction and exit essentially in the axial direction from the circular outlet opening forming the final product of the channel intended to obtain the final product (paragraph 8 claims). However, the present invention can also be used in so-called "peripheral" extrusion heads, that is, heads in which material is extruded in the radial direction from an annular exit slit, a slot in the cylindrical wall of the extrusion head. Such "peripheral" extrusion heads are known from food extrusion technology. In this application, the two streams, after combining, extend substantially radially all the way to the round outlet opening forming the final channel product.

As a preferred embodiment of ring extrusion, a spiral flow extrusion method is claimed (claim 24), and an extrusion die for this method is claimed in claim 39.

As indicated above, the extrusion of material B occurs in a pulsating manner, wherein said pulsation is usually carried out upstream of the closing flap (4), and this pulsation can be achieved using one or more plungers or by opening and closing the valves. These devices should preferably be close to where the components are connected. They should interact normally with (conventional) previous injection or extruding agents. If a plunger is used, a check valve is preferably used to prevent the plunger from pumping the material in the wrong direction (claim 9).

The term "check valve" in this case means not only a valve that closes under the action of backpressure, but also a valve that is actuated by means of control means, which causes it to close at the right time in the production cycle.

In most cases, the invention can be successfully used to apply not only one stream of material B, but also two streams of materials B (B1 and B2) onto the stream of material A, while material B1 is applied to one side of material A and material B2 to the other side of the material A. Materials B1 and B2 may be identical or different in composition (paragraph 10 of the claims).

As mentioned in the introduction, a first aspect of the invention relates to co-extrusion directed to coating material A, which during extrusion has a high specific viscosity, in thin layers of material B having a significantly lower specific viscosity.

The problems arising in this regard and the solution of problems through the use of the present invention have been explained in the introduction. The solution is more clearly shown in paragraph 11 of the claims and is further specified in paragraph 12 of the claims. Namely, material B or materials B1 and B2 have a lower specific viscosity compared to material A, and during each pulsation, the difference between the pressures in the flow or flows of material (s) B "and" in the flow of material A is sufficient to ensure uniform the deposition of material (s) B on the material A over the entire length of the hole (3), while the dimensions of the common channel (7) are adapted to provide a shear sufficient to make the thickness of the layers of materials B1 and B2 substantially uniform before the exit (8 ) at the end of the channel (7). In this case, the cross-sectional area of the channel (7) decreases in the direction of the end (8) located downstream. The need to create a significant pressure difference at each pulse between the flow or flows of material (s) B and the flow of material A, in other words, the need for shock-type pulsations, depends on the difference in specific viscosities. The speed of each flow of material B when it comes in contact with the flow of material A should preferably be in most cases, but not in all cases, substantially equal to or greater than a value equal to the flow rate of material A times the ratio of the specific viscosity of material A and the specific viscosity of the material In (under real conditions). The term “shock” refers to a pulsation of short duration, but with a high amplitude, that is, to a pulsating change in speed.

Thus, it becomes economically feasible to use even very expensive copolymers to modify the surface properties of cheap durable polymers - in this regard, reference is made to paragraphs 13 and 14 of the claims. Namely, material A preferably consists of high molecular weight polyethylene or high molecular weight polypropylene, and material B1 or materials B1 and B2 consists or consists of a polymer or a mixture of polymers that adheres to material A in the final product and has or has a flow index, at least 10 times and preferably at least 20 times the yield strength of material A. Moreover, materials B1 and B2 preferably occupy together less than 10% of the thickness of the combined stream.

In such cases, preferably there should be at least 5 pulsations per second.

The term “substantially uniform” means that material B should cover the surface of material A essentially continuously, but in addition, the ratio of the thicknesses of materials B and A should preferably not change by more than ± 50%, and more preferably should not change more than ± 25% of the average value of the ratio of the thickness of materials B and A.

In addition, components B1 and B2, applied as indicated in paragraph 11 of the claims, can have a significant lubricating effect and thereby cause a decrease in back pressure, for example, in the combinations stated in paragraphs 13 and 14 of the claims.

A second aspect of the invention, which has already been discussed in the introduction, is defined in paragraphs 15, 16 and 17 of the claims.

Namely, it is preferable that, at each pulsation, the pressure of materials A and B on the closing flap (4) is sufficient to substantially completely stop the flow of material A to obtain a segmented flow from components A and B with respect to the direction of extrusion. In addition, it is preferred that materials A and B have substantially the same specific viscosity. And it is most preferred that the combined stream after extrusion is cured, wherein materials A and B in the final solid form of the manufactured article have different elastic moduli.

In accordance with this aspect, the channel from the joint zone to the exit of the co-extrusion die should preferably be short in order to maintain a pronounced segment structure.

In a third aspect of the invention, a method is provided whereby a stream of solid, substantially dry particles is extruded together with a stream of truly fluid material, the stream of solid particles, which is component A, is pushed through a plunger (22) into a channel (18) that leads directly to the hole (s) (3) through which the truly fluid material, which is material B, is coextruded (claim 18 and FIGS. 5a and b). When material B combines with material A, the composite stream of materials A and B is preferably mixed and / or densified with one or more stamping elements or flaps (24 and 25) that move back and forth in directions transverse to the main direction of the composite stream ( claim 19).

In each of the three aspects of the invention, the co-extrusion process can be further continued so that several B / A or B1 / A / B2 material streams are combined into a “flat multi-layer structure”, this term indicating that the smallest size in the final product parallel to the smallest size of the individual layers or, alternatively, the flows can be combined into a “high multilayer structure”, that is, a design in which the smallest size in the finished product is essentially perpendicular to the smallest size ial layers. In the patent literature (for example, in the earlier patents of the applicant), the latter case is called “layered extrusion”.

In the event that the present invention is used in "layered extrusion" so that there are many exits (8) arranged in a linear order or around a circle, the composite flows exiting from these exits can be mechanically divided into segments, and between these segments segments can be introduced from another material extruded from other outlets arranged in the same linear or ring order to form a cellular structure, and this is explained in a pending patent application For an entity owned by the applicant for this application, see WO 00/60959.

As is apparent from the foregoing, the present invention is not limited to co-extrusion of synthetic polymers, but is also in many cases applicable for co-extrusion of food components (claim 20), or for production by co-extrusion or ceramic product (claim 22), or medical tablets (paragraph 23 of the claims). In the last two cases, component A can be extruded either as a stream of solid, substantially dry particles ejected by the plunger, as explained above, or it can be extruded as a paste containing particulate solids.

Regarding the co-extrusion of food components, it can often be very difficult or impossible to “tailor” their rheological properties to the extent necessary to achieve sufficient uniformity of layer thickness using conventional means, and in such cases the present invention is of particular importance . Thus, material B can be molten chocolate, sugar, or a caramel cooler, while material A is a higher specific viscosity material (claim 21). In this regard, reference is made to an example in which thin layers of molten, relatively flowing chocolate are extruded onto a plastic consistency marzipan.

In a preferred embodiment of the co-extrusion process, an annular extrusion die is used having an inlet and a substantially circular outlet, wherein to streamline the material flow through the outlet around the entire circumferential periphery of the latter, the material flow between the inlet and the outlet is divided into many partial spiral flows shape or spiral shape with the ability to control overflow between partial flows, and partial flows with overflows gradually merge are pulled into one common annular flow (paragraph 24 of the claims).

Moreover, it is preferable that the inlet channel is located closer to the axis of the annular extrusion head than the outlet, and the extrudable material extends outward towards the outlet.

Most preferably, the outlet is located closer to the axis of the annular extrusion head than the inlet, and the extrudable material extends inward toward the outlet.

Also proposed is an extruder containing an extrusion head for co-extrusion of a stream of extrudable material A with a stream of extrudable material B, while the extrusion head contains a connection zone in which material B is extruded onto material A through hole (3), outlet (8) and channel ( 7), through which the connected materials A and B pass from the hole (3) to the outlet (8), while the dividing wall between the flows immediately before its end in the hole (3) is made in the form of a closing flap (4) made with possibility to act as a check valve for the flow of material B to material A extruded, the extruder comprises means for extruding the material in through the hole (3) in a pulsating manner.

In this case, the closing flap is a spring knife, preferably with a thicker or harder portion at its end, located downstream.

Preferably, the pulsation device comprises one or more plungers or actuated valves located upstream of the closing flap (4).

Preferably, the pulsation means comprises a mechanical transmission means (4c) opening and / or closing the closing shutter (4).

Preferably, at least in the immediate vicinity of the opening (3), the extrusion head is configured so that both material flows A and B are flat flows that are substantially parallel to the closing damper (4).

In one preferred embodiment, the co-extrusion die is a slotted die for extrusion of a flat sheet or tape.

According to another preferred embodiment, the coextrusion extrusion die is an annular extrusion die designed for coextrusion of tubular flows, in which the closing flap (4) is made in the form of a ring with surfaces substantially perpendicular to the axis of the extrusion die.

In this case, it is preferable that the extrusion head is configured so that materials A and B, at least in the immediate vicinity of the hole (3), extend outward or inward in a substantially radial direction, and after connecting the flows, they are directed essentially in the axial direction and they exit essentially in the axial direction from the round outlet (8) to obtain the final product.

Preferably, the pulsation means comprises a plunger or plungers (1) with prior interacting injection or extruding means, characterized in that the check valve (2) prevents the material from being pumped back by the plunger in the direction of said previous means.

Preferably, the extruder is configured to attach two streams of material (s) B1 and B2 to both major surfaces of material A.

Preferably, the dimensions of the common channel (7) are selected with the possibility of providing a shift sufficient to make the thickness of the layers of materials B1 and B2 substantially uniform before the exit (8) at the end of the channel (7).

Preferably, the cross-sectional area of the channel (7) is reduced in the direction of the downstream end (8).

Preferably, the extruder comprises an extrusion head having an inlet (10) for the extrudable material and a substantially circular outlet located at different radial distances from the axis of the extrusion head, and there are channels between the inlet and the outlet for the extrudable material to pass through, one inlet channel passing from the entrance, branches at least once to form at least two channels (11, 12, 13) for partial flows, each of these channels is designed to create the flow of extrudable material, while the channels (11, 12, 13) for partial flows have a spiral slope and are located essentially in the plane or on the surface of the cone, and the channels for partial flows are gradually connected together.

Preferably, the outlet is located radially inward with respect to the inlet, the channels for partial flows spiraling inward towards the outlet.

Preferably, the outlet is radially outward from the inlet, the channels for partial flows spiraling outward towards the outlet.

Preferably, each of the channels (11) for partial flows following the inlet channel branches out to form two additional channels (12) for partial flows.

Preferably, each of the additional channels (12) for partial flows branches out to form two output channels (13) for partial flows that extend to the outlet.

Preferably, the means for extruding material A comprises a plunger (1) in a channel (18) leading directly to the hole (3).

Preferably, there is one or more stamping elements or flaps (24 and 25) downstream of the opening 3, which reciprocate in the direction transverse to the direction of extrudate flow to allow mixing and / or compaction of the composite material stream B and A.

Also provided is an extruder comprising a co-extrusion die for co-extruding a stream of extrudable material A, from which a sheet or tape is formed with a stream of extrudable material B, from which a sheet or tape is formed, wherein the extrusion head contains a connection zone in which the extrusion of material B onto material A through the hole (3), the outlet (8) and the channel (7) through which the connected materials A and B pass from the hole (3) to the exit (8), while the dividing wall Between the flows immediately before its end in the hole (3) is made in the form of a closing flap (4) for acting as a check valve for the flow of material B, extruded into the material A, characterized in that the extrusion head for co-extrusion is an annular extrusion head, intended for co-extrusion of tubular flows, in which the closing flap (4) is made in the form of a ring with surfaces essentially perpendicular to the axis of the extrusion head.

Preferably, the extrusion head is configured so that materials A and B, at least in the immediate vicinity of the opening (3), extend outward or inward in a substantially radial direction, and after connecting the flows, they are directed substantially in the axial direction and they exit essentially in the axial direction from the round outlet (8) to obtain the final product.

As an example of the use of the present invention in the process of co-extrusion, intended for the formation of ceramic products, we can cite the process of manufacturing porous membranes.

The invention will now be described in more detail with reference to the drawings, in which:

Figure 1 shows the distinctive part of the slit extrusion head for co-extrusion during operation according to the invention. The drawing is a section parallel to the direction of processing and perpendicular to the main surfaces of the flows of materials A, B1 and B2, from which a sheet or tape is formed.

2a and b are flowcharts graphically illustrating processes in annular extrusion heads for co-extruding pipes according to the invention. In FIG. 2 a, the flows move substantially from the outside inward, and in FIG. 2 b in a substantially opposite direction.

Figa and b show suitable designs of the distribution zones respectively in Fig.2a and b. They are images through the distribution channels for component A.

Fig. 3c, which is a modification of Fig. 1, shows a pool area (including plungers and an outlet) in the extrusion head of Fig. 2a. The drawing shows a section passing through the axis (9) of the annular extrusion head, but the distribution part of the extrusion head is omitted. The drawing also shows the area of association in the extrusion head according to fig.2b, but in this case, it is necessary to consider the axis (9) as located outside the sheet and under the drawing.

FIGS. 4a, b, c and d show various modifications of the component pooling zone, wherein these modifications relate to the design of the slotted extrusion head of FIG. 1 and / or to the ring structure of FIG. 3.

Figures 5a and b show a modification of the extrusion head of Figure 1, adapted to work with the substantially dry particulate component A and to expel it using a plunger. Fig. 5a is a section corresponding to the section of Fig. 1, while Fig. 5b, which is an image of only the area in the immediate vicinity of this plunger, shows a section aa of Fig. 5a.

Figure 1 shows that the three components A, B1 and B2 are fed into this part of the extrusion head for co-extrusion, as shown by three arrows. This feed is provided using basic, conventional feed means (extruders or pumps) that are not shown in the drawing. Conventional distribution means may be provided between these extruders or pumps and the device shown to ensure uniform distribution of the components across the width. Usually, material A passes in a continuous flow (but in some cases it can be extruded in a pulsating manner), while materials B1 and B2 are extruded in a pulsating manner, which is done using plungers (1), which ensure the combination of flows created by the main feed means . Check valves (2), which guarantee proper operation of the plungers, can, for example, be formed from spring knives.

At the holes (3), where materials B1 and B2 enter the chamber intended for material A, there are two spring knives (4), which are the protruding ends of the wall (4a) of the chamber intended for material A, or connected to this wall. Knives (4) are installed in the form of check valves. When they are under sufficient pressure created by material B1 and / or B2, they can even act as shutters for material A, so that after the flows are connected, segments (sections) of material A will alternate with segments (sections) of materials B1 + B2 (these two materials may have the same composition). However, this does not occur in the embodiment shown in the drawing. In this case, materials B1 and B2 are connected to material A in the form of “lumps [cones]” (5) on each of its surfaces. Since a sheet or tape is formed from the flows of materials A, B1 and B2, the shape of the knife (4) is adapted to this, these “lumps” will be transverse “threads”, the main direction of which is perpendicular to the image plane. The drawing shows the situation at the end of the ripple, when the knives (4) are in a position close to the position of closing the holes (3). The plungers (1) still continue to extrude, and therefore the check valves (2) are closed. The previously extruded “lump” is shown as an element with a reference number (6). In this case, the application of the invention, the specific viscosities of materials B1 and B2 are significantly lower than the specific viscosities of material A, the consequence of which is that the “lumps” will gradually be smeared or shifted to almost uniform layers, while the flow of B1-A-B2 will pass through a common channel ( 7) in the direction of exit (8) from the extrusion head for co-extrusion.

Consequently, the “lump” (6) is shown with smaller sizes in comparison with the “lump” (5), and further along the course no “lump” is shown.

Each of the plungers (1) can extend over the entire width of the flows of materials B1 and B2 from which a sheet or tape is formed, or preferably a number of plungers for material B1 and a row for material B2 can be provided (depending on the mechanical construction). However, in this case, it must be guaranteed that uniform pressure will be created from one to the other lateral edge of each of the flows when they enter the hole (3). This can be achieved due to the size of the chambers for materials B1 and B2, the distance between the plungers and the pressures of materials B1 and B2 during the process.

In the event that the plungers (1) extend over the entire width of the material A flow, the inlet channels (4b) for materials B1 and B2 in the area located upstream of the valves (2) must also pass in this way, but if provided rows of plungers, the feed to each plunger should preferably be from a separate channel. It may be necessary that the distance from the closing flap (4) to the opposite wall of the channel 4b along the length of this flap is very short with respect to the length of the flap (4), since otherwise this flap may be excessively bent towards the opposite wall when pressure material B1 or B2 will be minimal, and the pressure of material A will be high.

In some cases, especially in connection with the second aspect of the invention, in which the ripple frequency is generally not as high as in the first and third aspects of the invention, only one ripple producing narrow plunger (1) can be used for each of the components B for "Maintenance" of the entire width of the co-extrusion, even when this width is significant, provided that it is possible to efficiently distribute between this plunger and the hole (3), where the components are combined.

Flow charts 2a and b show consecutive zones in respective extrusion heads for co-extrusion ring according to the invention, while the drawings of FIGS. 3a and b, as already mentioned, illustrate a preferred corresponding component distribution system A. This system begins with a branching system, which was first described in US Pat. No. 2,820,249, in which it is used in connection with coating products by co-extrusion.

Component A is fed into this system through port (10), then it branches into two partial flows in channels (11), continues in the form of 4 partial flows in channels (12), and in the form of 8 partial flows in channels (13). (Depending on the size of the extrusion head, more or less partial flows can naturally be formed, but in any case their number should be even). Partial flows in the channels (13) continue in the “spiral” distribution system, pass through the grooves (14), as a result of which rheological calculations create the proper balance between the flows passing through the spiral grooves (14), and the overflow between the latter, which has a place in narrow gaps in spaces (15), the beginning of which is shown by lines (16).

A similar branching system can be rationally used for components B1 and B2, however, when an annular row of plungers is used, as shown, and these plungers are located quite close to each other, there is no need for a spiral distribution of these components, since each of the partial flows, which occurs as a result of separation, in this case can pass directly to the plunger, which is more practical. In addition, if the viscosities of components B1 and B2 are significantly lower than the viscosities of material A, a lower degree of branching of these two components will be sufficient.

In practice, the distribution system, which is designed for material A and shown in figa and b, can be implemented in an extrusion head or zone of the extrusion head, consisting of two disks that are screwed together. Channels (grooves) can be formed only in one of these disks, or preferably a part of each channel is formed in one and another part in another disk, while these parts of the channels are interfaced with each other.

However, as indicated in connection with FIG. 1, under certain conditions, one plunger will be sufficient for each component B, but in this case an effective distribution between the plunger and the hole (3) is required.

As indicated, figa, which shows in detail the "zone of association" of figa, is a modification of Fig.1. Reference numbers denote the same elements. It should be noted that the spring knives (4) in figure 1 are shown flat, but in this case, of course, they are made in the form of flat ring-shaped disks.

Similarly, if the chambers for materials B1 and B2, located directly in front of the check valves (2) along the flow, are cylindrical chambers around the entire extrusion head, as they may be, then the two valves (2) are also made in the form of flat, annular disks and can be installed in the system, as shown here, however, as follows from the foregoing, it is usually more practical to allow each of the partial streams that result from the separation to pass through edstvenno to the plunger on a separate channel, in which case the construction similar to that shown in Figure 1, is also applicable.

As shown in the drawing, the annular extrusion head should usually be adapted to extrude the composite stream B1 / A / B2 outward in a substantially axial direction when it leaves the outlet (8).

The plungers (1) can be actuated using direct mechanical, hydraulic, pneumatic or electromagnetic means. Usually more convenient is the actuation by hydraulic means. In the extrusion system (FIG. 2a), plungers are easily accessible from the outside of the extrusion head, however, in the outward extrusion system (FIG. 2b), one row of plungers must be driven through an open hole in the middle of the extrusion head. This open hole can also be used for other pipelines or connections, for example, for piping for cooling the extrudable pipe from the inside. It is obvious that the design of the extrusion head, in which the flows move inward (FIG. 2a), is best suited for the production of a tube plate or pipes of relatively small diameter up to 10 mm or less, while another design (FIG. 2b) is best used when they want to get a product with a relatively large diameter, for example, up to 5 m or more.

In the manufacture of pipes in which hard sections alternate with soft sections, the structure shown in FIG. 2a should be used.

The modifications shown in FIGS. 4b, c and d can be considered as modifications to the slotted extrusion head shown in FIG. 1, as well as modifications to the annular extrusion head shown in FIG. 3. The modification shown in Fig. 4a applies only to slotted extrusion heads (to Fig. 1), since if we consider the annular extrusion head, the closing flap becomes conical, and, naturally, in the form shown in Fig. 4a, she can't work.

A significant decrease in the thickness of the flow, which is seen in Fig. 4a, may be preferable if there is a need to reduce the back pressure of component A, as well as when using the lubricating action of components B1 and B2, and in this case, the flow at the end has the form of a relatively thin sheet.

Fig. 4a also illustrates the feature that the closing shutter (4) can be opened and / or closed using a mechanical transmitting means (4c) instead of using pressure fluctuations caused in component B (or B1 and B2), and, in addition to 4a, as well as FIGS. 4b-d, show a closing flap (4) in the form of a flexible knife ending in a thicker or harder part (4b) intended to reinforce and provide stability. Indeed, this part (4b) can be the main part of the shutter (4), while the shorter flexible part serves as a hinge.

The mechanical transmission means (17) in FIG. 4a are shown in the form of rods that push the thicker or harder part (18) of the closing flap. In the event that a significant pressure difference is required between component B (or B1 and B2) and component A (see paragraph 11 of the claims), it is obvious that the closing flap (4) must be adapted to withstand this differential pressure and keep the hole closed when it is not mechanically actuated. In an alternative embodiment of the invention, the mechanical transmission means (17) can be pivotally mounted on the parts (18) and can act by pulling or pushing-pulling.

The various arrangements and structures of the channels shown in FIGS. 4b, c and d can be selected in those cases where structural problems may arise while allowing the flows of components A and B to flow substantially parallel to each other before being combined. However, the abrupt change in flow direction shown in these sketches can, under certain circumstances, cause dangerous stagnation.

Figures 5a and b show that a substantially dry particulate product (A), which, for example, can be a starting material for ceramic products, plastics, for example polytetrafluoroethylene composite materials, food products or medical tablets due to gravity from the hopper through the feed chamber (17) to the channel (18) for the extrusion of material A. Air is preferably pumped out of the hopper, since air can create problems when performing joint extrusion, mixing and seals.

5 a, the upstream and downstream boundaries of the feed zone are shown with dashed lines 19 and 20. A vibrator or other mixing means (not shown) can facilitate the flow of material A due to gravity. Material A is pushed through the channel (18) using a plunger (21). In the rearward position of this plunger, its front surface substantially coincides with the rear boundary of the feed zone (dashed line 19). Before moving the plunger (21) forward to push material A, the connection between the hopper and the channel (18) is closed with a sliding closing element (22), as shown by arrow (23).

Fluid components B1 and B2 (which are usually identical) are extruded together in a pulsed manner by two plungers (1) through channels (4b) for extruding components B1 and B2 to an opening (3) containing a check valve (4), which is a closing valve a shutter, as explained in connection with FIG.

The movements of three plungers, one (21) of which is for material A and two (1) for components B1 and B2, can be simple reciprocating movements, but in particular for components B1 and B2 it is usually preferable that the plungers work was a sequence of moves forward, followed by a continuous retreat to its original position. The lubrication of the plunger (21) is preferably provided either by component B1 / B2, or by means of a fluid, which can be considered compatible with components B1 and B2 for reasons depending on the purpose of use of the final product. This lubricant may be introduced from the rear of the plunger or otherwise in a well-known manner. Means for this are not shown.

Advantageously, the lubricant must be injected into the co-extrusion system in amounts that are sufficient not only to lubricate the plunger (21), but also to lubricate the displaced material stream A as it passes to the bore (3).

The flowing components B1 and B2, which are extruded together on two surfaces of the flow of dry particles, may be able to penetrate into the middle of the flow of material A without using any mechanical mixing means, but usually such means are necessary if it is desired to obtain a sufficiently homogeneous mixture of materials A, B1 and B2. In the drawing, these means are flaps (24) that quickly vibrate, and their synchronous vibration is provided with respect to each other, and thereby subject the composite stream to a shear that occurs in a direction transverse to the main direction of flow. Shows transmitting the movement of the rods (24A), designed to implement these vibrations.

The combination of coextrusion and mixing in accordance with this aspect of the invention is particularly preferred if the ratio between the fluid components (B1 and B2) and the component (A), which is essentially dry particles, is relatively low, so that the mixed product as a whole is still has the appearance of particulate matter (as opposed to paste). When the composite stream has this form, it may be necessary to seal the material before it leaves the extrusion head. If only a small compression is required, a narrowing of the channel (7) may be sufficient, but the probability of blocking the narrowing channel by such particulate products is very high, and a situation may arise in which even the increased pressure acting on the plunger (21) will not provide the possibility of overcoming such blocking. This problem is solved by performing compression in the transverse direction using rapidly vibrating stamping elements (25), which are out of phase synchronized, so that they alternately move towards each other and from each other. These stamping elements cover the entire width of the composite flow, and the front of at least one of them is deflected relative to the main direction of flow, so that they provide a gradual decrease in the clearance of the channel. In the position in which the stamping elements are closest to each other, the distance between them should preferably be slightly less than the clearance of the outlet 8.

Instead of two stamping elements (25), only one can be used.

In this drawing, the mixing means (24) are shown in the form of flaps, but in the alternative, they can be made in the form of stamping elements (that is, represent an element that performs mixing in a substantially straight direction), while the means for compression are shown in the form stamping elements, but in the alternative, they can be sashes.

On figa it is seen that the surface of the flaps (24) and the front parts of the stamping elements (25) with some approximation can be considered essentially parallel to the surfaces of the co-extruded layers of components B1 and B2. However, this third aspect of the invention can also be implemented in such a way that a part of the device located behind the dashed line 26 along the course of the flow is considered to be rotated 90 ° around an axis parallel to the main direction of flow. Thus, it is possible to implement a device for co-extrusion with several outputs (8) located close to each other in a given order for the “layered coextrusion”, which was mentioned above. When using this embodiment of the invention, “layered extrusion” can be used, for example, as an improved method for the manufacture of medical tablets that release active substances in the body in several stages with predetermined time intervals, that is, they realize the function of tablets, which in itself is good known.

Example

This example illustrates the use of the invention for the production of a new confectionery product, which can be expected to have an attractive presentation, namely for the production of corrugated (wavy) thin pieces of marzipan, coated on both sides with thin layers of dark chocolate. In principle, this can be accomplished using conventional co-extrusion, when the chocolate is in a semi-molten, highly viscous state with a specific viscosity quite close to the specific viscosity of the plastic mass of marzipan. However, the temperature range at which dark chocolate can be in the molten state is very small, and chocolate has a great tendency to supercool and thereby remain virtually fluid instead of partially curing when it is gradually cooled from the molten state. This means that it is very difficult to “tailor” the rheological properties of dark chocolate to such a joint extrusion. Therefore, the present invention is used, and the chocolate is held in a substantially molten and fluid state while it is coextruded with a plastic mass of marzipan.

The process is performed on an experimental co-extrusion line, in which the extrusion head has essentially the same design as shown in figure 1, however, the output of the extrusion head, starting from the point where the channel (7) begins to narrow, gradually changes to a wavy shape, then there are sides of the slit are parallel and have a wavy shape, while the angle at the midpoints is approximately 30 ° relative to the direction of the wave. The clearance of the output part (8) is 2.5 mm, and the width of this and the corresponding channels in the extrusion head is 30 mm. The height of the channel (7) before narrowing is 4.0 mm, the height of the channel for component A (marzipan) before combining is 3.0 mm. The height of the two channels for component B (chocolate) is 2.0 mm at the beginning, but varies up to 1.0 mm along the knives (4). This low height is chosen to ensure that the knives (4) will not bend improperly under pressure from the component A. The length of the knives (4) is 16 mm and the thickness of the knives is 0.20 mm in the first 5 mm and 0.40 mm on the rest of the length. The length of the channel (7) before narrowing is 100 mm.

Component A (marzipan) is continuously fed by means of a conventional hydraulically driven plunger extruder, and component B (molten chocolate) is also mainly fed by a conventional plunger extruder (not shown), but in this case with a pneumatic drive. The reason for using a hydraulic actuator to drive the plunger for component A is because of the relatively high required pressure, while the reason why the plunger for component B is driven by a pneumatic drive is partly because of the lower required pressure and partly as needed achieving a certain “buffer” effect so that the pressure in component B located upstream of the check valves (2) along the flow does not increase excessively when these valves are closed.

Due to the very small width of the extrusion head in this experimental line, no distribution means are used between the main plungers and the parts of the extrusion head shown in FIG.

Each of the (auxiliary) plungers (1) located directly in front of the unification zone along the course of the flow covers the entire width of the flows. Their pistons have a rectangular cross-section with a cross-sectional size of 29.95 mm × 1.95 mm. Their movements are carried out using a direct mechanical drive with adjustable strokes. They perform successively 10 moves forward, followed by a return to their original position.

The temperature of the material B is maintained at 40 ° C, and the temperature of the material A is maintained at 15 ° C until these components enter the extrusion head. The reason for using this relatively low temperature is to help cool material B.

The temperature of the extrusion head is maintained at 32 ° C. Under equilibrium conditions, the chocolate will be partially melted at a given temperature, but under real conditions of this extrusion it becomes supercooled and remains truly fluid except where it comes in direct contact with cold marzipan.

The pressure in the plunger for material A is adjusted to provide a capacity of 15 g / s. Under real conditions, this corresponds to a pressure of approximately 50 bar (5 × 10 ⁶ Pa). The main plunger for material B extrudes at a pressure of approximately 10 bar (1 × 10 ⁶ Pa).

Auxiliary plungers (1) for material B operate with strokes lasting approximately 0.05 s with a period (stroke + break) of 0.1 s, which corresponds to 10 strokes per second. The stroke amplitude is adjusted to obtain a chocolate coating [thickness] of 0.4 mm on each side of the marzipan.

The wavy “ribbon” of chocolate coated marzipan is rather stiff when it leaves the outlet (8) of the extrusion head. It travels a distance of 2 mm without leaning on a support, and after that it is transported using a conveyor. Cold air is blown to cool. While the “belt” is on the conveyor belt, it is cut into short pieces.

Claims (50)

1. The method of co-extrusion of the stream of extrudable material A with the flow of extrudable material B in the joint zone in the head for co-extrusion, in which the extrusion of material B onto the material A through the hole (3), two materials pass together through the channel (7) the outlet side (8) of the head, while the separation wall between the streams immediately before its end in the hole (3) is made in the form of a closing flap (4), configured to act as a check valve for the flow of material B, extrudable onto material A, characterized in that the extrusion of material B through the hole (3) is carried out in a pulsating manner. 2. The method according to claim 1, characterized in that the closing flap is a spring blade, mainly with a thicker or harder section at its end, located downstream. 3. A method according to any one of claims 1 and 2, characterized in that the pulsation is carried out using one or more plungers (1) or by opening and closing valves located upstream of the closing flap (4). 4. The method according to any one of claims 1 and 2, characterized in that the pulsation is carried out by opening and / or closing the closing flap (4) using mechanical transmitting means (4c). 5. The method according to any one of claims 1 to 4, characterized in that at least in the immediate vicinity of the opening (3) the flows of materials A and B are plane flows that are essentially parallel to the closing shutter (4). 6. The method according to any one of claims 1 to 5, characterized in that the extrusion head for co-extrusion is a slotted extrusion head, extruding a flat sheet or tape. 7. The method according to any one of claims 1 to 5, characterized in that each of the materials A and B at the junction forms a tubular flow, and the extrusion head for co-extrusion is an annular extrusion head in which the closing flap (4) is made in in the form of a ring with surfaces substantially perpendicular to the axis of the extrusion head. 8. The method according to claim 7, characterized in that the materials A and B, at least in the immediate vicinity of the hole (3), extend outward or inward in a substantially radial direction, and after connecting the flows, they are directed essentially in the axial direction and they exit essentially in the axial direction from the round outlet (8) forming the final product. 9. The method according to any one of claims 1 to 8, characterized in that the plunger or plungers (1) are used in conjunction with upstream injection or extruding means, and the check valve (2) prevents the material from being pumped back by the plunger in the opposite direction funds. 10. The method according to any one of claims 1 to 9, characterized in that two streams of materials B1 and B2 are attached to both main surfaces of the material A. 11. The method according to any one of claims 1 to 10, characterized in that the material B or materials B1 and B2 have a lower specific viscosity compared to material A, and during each pulsation, the difference between the pressures in the stream or flows of material B and the flow of material A is sufficient to ensure uniform deposition of material B on material A along the entire length of the hole (3), while the dimensions of the common channel (7) are adapted to provide a shear sufficient to make the thickness of the layers of materials B1 and B2 substantially uniform per d outlet (8) at the end of the channel (7). 12. The method according to claim 11, characterized in that the cross-sectional area of the channel (7) decreases in the direction of the end (8) located downstream. 13. The method according to p. 12, characterized in that the material A consists of high molecular weight polyethylene or high molecular weight polypropylene, and material B1 or materials B1 and B2 consist of a polymer or a mixture of polymers that adheres to material A in the final product, and have a yield index of at least 10 times and preferably at least 20 times that of material A. 14. The method according to item 13, wherein the materials B1 and B2 together occupy less than 10% of the thickness of the combined stream. 15. The method according to any one of claims 1 to 10, characterized in that, at each pulsation, the pressure of materials A and B on the closing flap (4) is sufficient to substantially completely stop the flow of material A to obtain a segment flow from components A and B with respect to to the direction of extrusion. 16. The method according to clause 15, wherein the materials a and b have essentially the same specific viscosity. 17. The method according to any one of paragraphs.15 and 16, characterized in that the combined stream after extrusion is cured, and materials A and B in the final solid form of the manufactured product have different elastic moduli. 18. The method according to any one of claims 1 to 10, characterized in that the material A consists of substantially solid dry particles, and the material B consists of a fluid material, the flow of material A being expelled using a plunger (21) in the channel (18) that leads directly to the hole or holes (3) through which material B is coextruded. 19. The method according to p. 18, characterized in that after the connection of material B with material A, the combined stream is subjected to mixing and / or compaction using one or more stamping elements or wings (24 and 25), which move reciprocally in the directions transverse to the main direction of the combined flow. 20. The method according to any one of claims 1 to 12, characterized in that the materials A and B are composed of food components. 21. The method according to claim 20, characterized in that the material B is a molten chocolate, sugar or caramel cooler, and the material A is a material having a higher apparent viscosity compared to material B. 22. The method according to any one of claims 1 to 10, 18, 19, characterized in that at least component A contains solids in the form of particles for the formation of ceramics. 23. The method according to any one of claims 1 to 10, 18, 19, characterized in that at least component A contains solids in the form of particles for the formation of tablets for medical purposes. 24. A method according to any one of claims 7 and 8, characterized in that they use an annular extrusion head having an inlet and a substantially circular outlet, while for aligning the flow of material through the outlet across the entire peripheral periphery of the latter, the material flow between the inlet and the output is divided into many partial flows of spiral shape or spiral shape with the ability to control overflow between partial flows, and partial flows with overflows are gradually combined into one common rotating arm flow. 25. The method according to paragraph 24, wherein the inlet channel is located closer to the axis of the annular extrusion head than the outlet, and the extrudable material extends outward towards the outlet. 26. The method according to paragraph 24, wherein the outlet is located closer to the axis of the annular extrusion head than the inlet channel, and the extrudable material extends inward toward the outlet. 27. An extruder comprising an extrusion head for co-extruding a stream of extrudable material A with a stream of extrudable material B, wherein the extrusion head contains a connection zone in which material B is extruded onto material A through hole (3), exit (8) and channel ( 7) through which the connected materials A and B pass from the hole (3) to the outlet (8), while the dividing wall between the flows directly in front of its end in the hole (3) is made in the form of a closing flap (4) made with the possibility of act as a check valve for the flow of material B, extrudable into material A, characterized in that it contains means for extruding material B through the hole (3) in a pulsating manner. 28. The extruder according to item 27, wherein the closing flap is a spring knife, preferably with a thicker or harder section at its end, located downstream. 29. An extruder according to any one of paragraphs.27 and 28, characterized in that the pulsation means comprises one or more plungers or actuated valves located upstream of the closing flap (4). 30. An extruder according to any one of paragraphs.27 and 28, characterized in that the means for effecting pulsations comprises a mechanical transmitting means (4c) opening and / or closing the closing shutter (4). 31. The extruder according to any one of paragraphs.27-30, characterized in that, at least in the immediate vicinity of the hole (3), the extrusion head is configured so that both material flows A and B are flat flows that are essentially parallel to the closing flap (4). 32. The extruder according to any one of paragraphs.27-31, characterized in that the extrusion head for co-extrusion is a slotted extrusion head for extrusion of a flat sheet or tape. 33. An extruder according to any one of paragraphs.27-31, characterized in that the co-extrusion extrusion head is an annular extrusion head designed for co-extrusion of tubular flows, in which the closing flap (4) is made in the form of a ring with surfaces essentially perpendicular axis of the extrusion head. 34. The extruder according to claim 33, wherein the extrusion head is configured so that materials A and B, at least in the immediate vicinity of the hole (3), extend outward or inward in a generally radial direction, and after joining their streams are directed essentially in the axial direction, and they exit essentially in the axial direction from the round outlet (8) to obtain the final product. 35. An extruder according to any one of paragraphs.27-34, characterized in that the means for effecting pulsation comprises a plunger or plungers (1) with previous interacting injection or extruding means, wherein the check valve (2) prevents the material from being pumped back in the plunger side of the foregoing funds. 36. The extruder according to any one of paragraphs.27-35, characterized in that it is made with the possibility of attaching two streams of materials B1 and B2 to both main surfaces of the material A. 37. The extruder according to any one of paragraphs.27-35, characterized in that the dimensions of the common channel (7) are selected with the possibility of providing a shift sufficient to make the thickness of the layers of materials B1 and B2 essentially uniform before the exit (8) at the end channel (7). 38. An extruder according to claim 37, characterized in that the cross-sectional area of the channel (7) decreases in the direction of the end (8) located downstream. 39. The extruder according to any one of paragraphs 33 and 34, characterized in that it comprises an extrusion head having an inlet (10) for the extrudable material and a substantially circular outlet located at different radial distances from the axis of the extrusion head, located between the inlet and channels for the passage of extrudable material through them, and one inlet channel passing from the entrance branches at least once to form at least two channels (11, 12, 13) for partial flows, with each of these channels It is intended to create a partial flow of extrudable material, while the channels (11, 12, 13) for partial flows have a spiral slope and are located essentially in the plane or on the surface of the cone, and the channels for partial flows are gradually connected together. 40. The extruder according to § 39, wherein the outlet is located radially inside relative to the inlet, and the channels for partial flows pass in a spiral inward towards the outlet. 41. The extruder according to § 39, wherein the outlet is located radially outward relative to the inlet, and the channels for partial flows pass in a spiral outward towards the outlet. 42. An extruder according to any one of claims 39 to 41, characterized in that each of the channels (11) for partial flows following the inlet channel branches out to form two additional channels (12) for partial flows. 43. The extruder according to claim 42, characterized in that each of the additional channels (12) for partial flows branches out to form two output channels (13) for partial flows that pass to the outlet. 44. The extruder according to claim 27, wherein the means for extruding the material A comprises a plunger (1) in a channel (18) leading directly to the hole (3). 45. The extruder according to claim 44, characterized in that there is one or more stamping elements or flaps (24 and 25) downstream of the hole (3) that reciprocate in the direction transverse to the direction of flow of the extrudate to allow mixing and / or sealing the composite flow of materials B and A. 46. An extruder containing an extrusion head for co-extrusion of a stream of extrudable material A with a stream of extrudable material B, while the extrusion head contains a connection zone in which the extrusion of material B through material A through the hole (3), the outlet (8) and the channel ( 7) through which the connected materials A and B pass from the hole (3) to the outlet (8), while the separation wall between the flows immediately before its end in the hole (3) is made in the form of a closing flap (4) to act as a back valve for the flow of material B, extrudable into material A, characterized in that the co-extrusion extrusion head is an annular extrusion head designed for co-extrusion of tubular flows, in which the closing flap (4) is made in the form of a ring with surfaces, essentially perpendicular to the axis of the extrusion head. 47. The extruder according to claim 46, wherein the extrusion head is configured so that materials A and B, at least in the immediate vicinity of the hole (3), extend outward or inward in a substantially radial direction, and after joining their streams are directed essentially in the axial direction, and they exit essentially in the axial direction from the round outlet (8) to obtain the final product. Priority on points: 04/13/2000 according to claims 1, 2, 3-6, 9-17, 20, 22, 27-29, 31, 32, 35-38, 44; 12/22/2000 according to claims 4, 7, 8, 21, 24-26, 30, 33, 34, 39-43, 46, 47; 04/11/2001 according to claims 18, 19, 23, 45.

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