DE2335055B2 - METHOD AND DEVICE FOR MANUFACTURING A COMPOSITE, STRUCTURED FILTER STRAND FOR TOBACCO SMOKE FILTERS OR THE LIKE - Google Patents

Description

same direction is promoted with him, that

Extniders to form an endless tubular Workpiece is extruded, the tubular workpiece conveyed away from the opening mentioned

Workpiece with a cross-sectional dimension ex- 15 becomes a cohesive, but tension-free cable is truded, which is larger than the cross-section of several continuous threads of beveled filler material in the workpiece and in the same direction is conveyed to him, the workpiece with a cross

extrusion dimension that is greater than

Final dimensions of the envelope, the tubular
Workpiece uniformly in a ring against the endless cable and sufficiently close to it.

is pulled to compress the cable radially, 20 the final cross-sectional dimensions of the sheath that by the workpiece through the opening of a tubular workpiece uniformly annular ge-closing device of substantially the same dimension as the final outer dimension

Solution of the shell is promoted, whereby the shell

the endless cable is pulled tight enough onto it.

_öm; In such, from US-PS 35 79 623

via 7aV κΥίεΓ ^ οπηΐ becomes, and * then * the 25 (DT-AS 19 36429) known method is obtained tubular workpiece is cooled to the one cigarette filter rod, the shell of a smooth to fix its outer dimension, thereby having outer and inner surface, whereby the Hafk e η η ζ e i c h η e t that the molten ther- ment between the filter mass and the thermoplastic Contains blowing agent and during its see envelope is relatively small and the mouthpiece movement through the extruder at least one paper during the application of the cigarette passage from a zone substantially above the paper adheres poorly

Atmospheric pressure of increased pressure to an Aus US-PS 34 04104, 35 02 754 and 32 99192

Zone in which a sudden drop in pressure are also foamed extrusion processes takes place in the thermoplastic material, plastics, for example in the form of pipes and is subjected to the development of foamed 35 the use of foamed plastic coatings for ■ - - - ■ Wires and cables known. From US-PS 34 63 652 is

a method for producing a foam-covered, oriented fiber is known in which

a coating of a molten

Means from the thermoplastic material to facilitate making the thermoplastic material foams and is placed in an expanded state.

2. The method as claimed in claim 1, characterized in that the thermoplastic material denotes the blowing agent, that the thermoplastic material is kept at a temperature above the decomposition temperature of the blowing agent, but below the melting temperature of the fiber material. The procedure and the device, however, is not suitable for pulling open the casing of a cigarette filter rod.

Compared to US-PS 35 79 623 the object of the invention is to provide a method by the production of a cigarette filter rod with improved adhesion between the fiber mass

for extruding the foamed shell from 50 and the shell on the one hand and the shell and the thermoplastic material in the form of an end-tip paper on the other hand,
loose hoses, a second device for conveying the fiber mass into the endless hose

material polyethylene is used.

3. The method according to claim 1, characterized in that the thermoplastic material is used Polypropylene used.

4. Apparatus for performing the method according to claims 1 to 3, containing a Nozzle device with a passage through which the thermoplastic material is conveyed,

and in the same direction with this and a Einpp

According to the invention, this object is achieved in that the molten thermoplastic blowing agent contains and during a movement through the Ex-

direction for cooling the assembled gear 55 at least one pass from a zone object, characterized in that the increased by significantly above atmospheric pressure Implementation of a restricted flow zone of pressure to a zone in which there is a sudden drop (38) and a low pressure foaming zone of pressure in the thermoplastic material instead- (40) takes place downstream of the flow restriction zone, is subjected to the development of the (38) in the flow direction of the thermoplastic 60 blowing agent from the thermoplastic material

Contains material and that the nozzle on the front surface of the nozzle outlet (42) with a plate (62) is provided to prevent the extruded material from adhering to the front surface of the nozzle outlet (42) to prevent.

5. Apparatus according to claim 4, characterized in that the nozzle has a channel (44) for the passage of the thermoplastic material

facilitate, whereby the thermoplastic material foams and puts it in an expanded state will.

The thermoplastic material used is preferably polyethylene or polypropylene.

The invention also relates to a device for performing the aforementioned method, which has a nozzle device with a

tion, through which the thermoplastic material is conveyed, for extruding the foamed Sheath made of thermoplastic material in the form of an endless tube, a second device for Conveying the fiber mass in the endless tube and in the same direction with this and a device for cooling the assembled article contains

To carry out the method according to the invention, such a method, likewise from US Pat. No. 3,579,623 known device developed in such a way that the implementation of a flow restriction zone and a low pressure expansion zone downstream of the flow restriction zone of the thermoplastic material and that the nozzle on the front surface of the nozzle outlet is provided with a plate to prevent the extruded material from adhering to the front surface the nozzle outlet.

Preferably, the nozzle has a channel for the passage of the thermoplastic material, which is angled is arranged to the conveying direction of the fiber mass.

The advantages brought up by the invention exist in particular that the application of a shell made of a foamed plastic material a filter rod is made possible in a continuous process. The one tied to the fiber strand Sheath made of the foamed thermoplastic material can also be relatively thin

The term »draw-down« used at the beginning is customary in the industry and relates on the ratio of the diameter of the extrudate after it emerges from the nozzle to the diameter of the finished product. This ratio must be greater than 1 so that there is enough space at the nozzle remains to extrude the strand without bonding and still cause the thermoplastic Sheath grips the filter rod and compresses it. This will hold the strand tightly together guaranteed by the thermoplastic shell and eliminated the possibility of cavities that the tobacco smoke could bypass the filter.

In the drawings is

F i g. 1 is a partially sectioned side view of an apparatus for producing the with a filter rod provided with a cover made of foamed plastic according to the invention,

F i g. 2 is a partial view of a device for deforming the strand and for covering it with plasticizer before being put into the device of FIG. 1 is introduced,

F i g. Figure 3 is a perspective view of a fiber optic cable-filled one made according to the invention Filter rod,

F i g. Figure 4 is a side elevational view, partially in section, of a nozzle assembly that is particularly useful suitable for carrying out the method according to the invention,

FIG. 5 is a side view of the mandrel of FIG. 4 nozzle arrangement shown,

6 is a partial plan view along line AA of FIG. 5 and

F i g. Figure 7 is a side view, partially in section, of another modification of the nozzle portion the device of FIG. 4th

The invention relates in particular to a device and a method for coating a Strand of filter material or similar objects with a thin cover made of a foamed ♦ en Thermoplastics. The device for producing such a product has a nozzle arrangement which is designed as shown in FIG. 1 of the aforementioned US-PS 35 79 623 shown, with the difference, however, that the nozzle arrangement is modified so that the method according to the invention can be carried out can. The modified nozzle arrangement according to the invention will be described in more detail below will. However, the cooling chamber portion of the device according to the invention is essentially like the cooling chamber described in the aforementioned US-PS 35 79 623.

In order to facilitate understanding of the invention, reference should first be made to FIGS. 2 and 3 are referred to will. F i g. 3 shows a short piece of a cigarette filter rod 10, which has a thin-walled outer shell 12 made of foamed plastic of circular cross-section with an outer surface 13, which is a Filter 16 comprises a fiber mass or a tow of cellulose acetate filaments, the tow al? Filter medium is used when a short piece or a plug of this strand is inserted into a cigarette will have.

As a preliminary stage for the production of the cigarette filter rod 10, the filter medium is made of a Preformed tow of cellulose acetate fibers as shown in FIG. 2 illustrates. To be from a supply Fibers or threads 18 passed through a preform chamber 20, in which they with a suitable amount of Plasticizers, for example a solution of 9 percent by weight triacctin, are coated. Of the Plasticizer is used for its usual purpose, i.e. H. for connecting the fibers in the cable to one another used at the contact or crossing points to form a continuous fiber mass. After exiting the chamber 20, the cable is guided through a set of feed rollers 22 and follows a U-shaped path. as indicated at 24 so that the tension in the cable is in the The longitudinal direction is canceled because the cable to be processed later preferably does not have any tension should have. Thereafter, the cable enters a collecting chamber 26 and is from there into a cross-head 28, which is shown in FIGS. 1 and 4 is introduced. The diameter of the out of the collection chamber 26 exiting strand is larger than the inner diameter of the casing to be produced, however smaller than the diameter of the extrudate emerging from the crosshead 28.

The cross-head 28 has a body 30 and a mandrel 32 supported therein in a known manner on. The body 30 includes an annular passageway 34 for introducing the molten mass of thermoplastic material from an extruder (not shown). Body 30 and mandrel 32 are like that arranged that they the passage 34 through which the mass of molten thermoplastic in a tapered zone or passageway 36, a flow restriction zone or passageway 38 and then into a low pressure zone or a passageway 40 in which the foaming of the thermoplastic material takes place, limit. The passageway 40 is in contact with the atmosphere Compound and is therefore kept at atmospheric pressure. While the mass of melted

thermoplastic material flows through the passage 36, the pressure initially falls, increases but then in the flow restriction zone or the passage 38, which is designed so that the pressure in it can rise to significantly above atmospheric pressure. When the crowd is out thermoplastic material enters the passageway 40 is due to the sudden slackening the pressure causes a foaming of the thermoplastic mass, which makes it possible to apply the coating to produce the extrudate as it emerges from the nozzle 42.

This structure is extremely important because otherwise the foaming in an uncontrollable manner takes place at nozzle outlet 42, making it extremely difficult, if not impossible, to apply the coating to pull up on the extrudate.

The passage 38 is a relatively short conduit which is designed so that the pressure can increase therein before the mass of thermoplastic material in the passage 40, in which starts foaming occurs.

Was led around the mass of thermoplastic material ^'1 by a channel 44 which extends at an angle to thy nozzle outlet 42 to the mandrel. This angular arrangement is essential because it allows a desired orientation and more uniform distribution of the mass of thermoplastic material around the entire mandrel. If desired, the channel 44 can be designed so that it ends in a compensating rib at 44a (FIG. 5) in order to bring about a pressure equalization and thus to improve the mixing effect for the mass of thermoplastic material. For its use with the foaming plastic, however, the nozzle is preferably designed in such a way that the channel 44 is a channel running continuously on the circumference of the dome 32.

If desired, the body 30 can be provided with an adjustable insert ring 46. This Insert ring 46 is used to adjust the width of the passageways 36 and 38 when he is in his with Threaded seat 46 a is adjusted axially to allow better pulling.

After it emerges from the nozzle outlet 42, the filter rod coated with the foam becomes passed through a cooling assembly 48 where the final product is formed. This cooling arrangement is essentially the same as the cooling chamber 40 and associated parts disclosed in the referenced U.S. Patent 35 79 623 described in detail and shown in FIG. 1 of that U.S. Patent. Of course, minor Modifications may be required to the cooling arrangement shown there for the purpose of the present Adapt invention. For example, while several dressing rings 54 to 58 are provided in the known device, suffice for the Implementation of the method according to the invention two or three such rings. Further modifications can, insofar as they prove necessary, be carried out by a specialist without further ado will.

According to FIG. 4, the filter rod is guided through the passage 49 in the core 50 of the nozzle arrangement. When the strand is softened, the core 50 is provided with cooling tubes 52 in a cooling channel 54 with a water inlet at 56 and a water outlet (not shown). If, however, a non-plasticized cable is used, cooling ducts and cooling pipes as well as water inlet and outlet can be omitted.
A channel 58, which is connected to a vacuum source (not shown), for example at 60, can also be assigned to the core 50. Although this arrangement is not essential, it makes it easier to connect the foam casing made of the thermoplastic material to the filter rod and enables the casing to be partially pulled open before it enters the cooling arrangement 48.

During the operation of the device described here, the foaming mass from the thermoplastic Material has a certain tendency to adhere to the surface of the nozzle at its exit 42. This accumulation of foamed plastic significantly interferes with the operation of the device and must therefore be prevented. As shown in FIG. 7 shown by the fact that the front surface of the nozzle outlet 42 with a relatively thin outer plate 62, preferably from Polytetrafluoroethylene or other similar materials. The plate 62 has an opening that is equal to the outer diameter of the nozzle opening and is in alignment with it. The plate 62 can by means of a steel retaining ring 64 or any other suitable means on the nozzle body be attached. The retaining ring 64 has an opening that is slightly larger than the opening of the nozzle, the possibility of contact with the mass of foamed thermoplastic material largely reduce. On the other hand, the opening must of course not be much larger than that Plate 62, as this plate can otherwise slide off the front surface. The preferred difference dei The diameter of these two openings is about 0.32 cm.

For the operation of the above-described device according to the invention, an extruder is used suitable polyolefin (e.g. polyethylene) having about 0.35 to about 0.70 weight percent of one suitable blowing agent mixed, either by agitation or by other means, and the mixture is then placed in a (not shown) filling

nozzles introduced. The nozzle is kept at a temperature in the range from about 182 to about 227 ° C. and a window ^{pressure between about 10 6} Pa and about 1.7 × 10 ⁷ Pa, depending on the speed and the thermoplastic used

is worked so that the mass of the thermoplastic material in the molten state ge will hold. Under these conditions there decomposes; Blowing agent, so that it rushes inside the nozzle Forms foam. The polyethylene mass flows ir the passageways 34 and 36 and strides under the The effect of the extruder against the nozzle outlet 4i continues, begins to foam at the passage 40 and from the nozzle outlet 42 of the extruder a coherent foam tube (sleeve 12

made of polyethylene and is made by conventional «devices, such as those in Fig. 1 of the aforementioned US-PS 35 79 623 are shown, promoted further. Ai at this point is the cross-sectional dimension of the Ex trudats considerably larger than intended "

Cross-sectional dimension of the finished filter rod, unc the extrudate is plastically deformable and has tough ( Interior surfaces. In addition, the foamed extrudate has a surface configuration at this point

which is essentially the same as that of the finished product.

Simultaneously with the exit of the foam sleeve 12 from the nozzle, this proceeds as above Referring to FIG. 2 through the crimped cable 14 formed in the mandrel 32 Passage 38 continues. The cable 14 slides axially into the extrudate as it exits the nozzle 28 from the foamed thermoplastic and progresses in the same direction as this. It has Cable at this point has a diameter that is at least slightly larger than the inner diameter of the Shell (of the foam extrudate) when it is completely worked up. Stand for a short distance the extrudate 12 and the cable 14 after their exit in the same direction from the Cross-head 28 not in contact with each other. As this distance progresses, the extrudate can shrink, so that the first contact with the cable only immediately before entering the cooling chamber 48 takes place.

After exiting the nozzle outlet 42, the assembled object is passed through the cooling chamber 48 out and there essentially, as described in the aforementioned US-PS 35 73 623, cooled, with the exception that only two dressing rings are used in the cooling chamber. The usage of more than two dressing rings is generally not necessary, as with two such Wrestling a product with a smooth outer surface is obtained.

When using the modified nozzle according to the invention, draw-up ratios of at least about 2: 1 can be achieved. However, the nozzle device according to the invention is general designed to achieve a draw-up ratio of about 1.7: 1.0.

The foam-covered filter plugs according to the invention have a much better one Ability to hold the cable in place as corresponding items made by conventional methods on. This improvement is due to the rough inner surface of the filter plug and it is considerably improved Pulling up, which is caused by the formation of the nozzle, can be traced back.

As mentioned above, blowing agents are used in the foam generation zone of the nozzle assembly to foam a plastic. These blowing agents are the ones that are among the most applied Operating conditions do not evaporate, but instead give off gaseous substances, through which the plastic is foamed, decompose. Such blowing agents are known. Examples of this are Ι, Γ-azobisformamide, 2,2'-azobisisobutyronitrile, 4,4'-oxybis (benzenesulfone hydrazide). Dinitrosopentamethylenetetramine. Trihydrazino-s-triazine and the like

The following examples illustrate the invention.

cell-screw extruder, which is equipped with a cross-head, as shown in FIG. 4 is shown, was connected, filled. The nozzle orifice and dome diameters were 1.425 and 1.37 cm, respectively. A 3.3 denier / 35,000 total denier crimped cellulose acetate tow that had been spread, preformed, and softened with a 10% triacetin solution was passed through a cooling trough with two circular dressing plates with a 0.813 cm diameter passageway to a take-off device, which reached an operating speed of 76.3 m / min. The extruder rotation speed was 32 rpm and the window pressure was 1.44 x 10 ⁷ Pa. The extruder consisted of three zones which were kept at temperatures of 180, 193 and 221 ° C, respectively. The nozzle throat and body temperatures were 260 ° C and the cooling water temperature was 10 ° C at the first zone of the extruder and 7 ° C at the second zone. The cooling tank was kept under a vacuum of 2.5 cm of water.

The product obtained was somewhat translucent, uniform and slightly roughened Exterior surface. The thickness of the coating was 0.028 cm and its circumference was about 24.6 mm. The weight the plug wall was about 27% less than that of a corresponding product that after coated using a conventional method and without foaming the thermoplastic material

Example 2

100 parts of polypropylene resin having a density of 0.90 g / ml and a melt index of 5.0 as in Example 1, mixed with 0.3 parts of paraffin oil in a V-type mixer. After that, the mixture 0.5 parts Ι, Γ-azobisformarnide and 0.52 parts Zinc oxide powder was added and the ingredients were added thoroughly mixed. The Gemiscr obtained was in the filler neck of an extruder mi a cross-head as in example 1. The conditions applied in this example i was:

Pick-up speed 61 ra'min

Extruder, 40 rpm

Window pressure 1.6-10 ⁷ Pa

Extruder zone 1 191 ° C

Extruder zone 2 204 ° C

Extruder zone 3 221 ° C

Nozzle neck 260 ° C

Nozzle body 260 ° C

Vacuum no

Cooling water zone 1 13 ⁼ C

Cooling water zone 2 10 ^c C

example 1

Polyethylene with a density of 0.924 g / ml and a nominal melt index of 1.1 was used with 0.3 parts by weight of paraffin oil (N.F. grade) were circulated in a mixer, and the mass became 0.5 parts by weight Ι, Γ-azobisformamide added. The mixture was then circulated for an additional 10 minutes. This Mixture was poured into the filler neck of a one-The product obtained was hot and opaque m: a rough surface and a wall thickness of 0.02 cm.

Example 3

The procedure of Example 1 was repeated using the same polyethylene, 0.3 part: len paraffin oil, 1.0 part of titanium dioxide and 0.5 part

len Ι, Γ-azobisformamide. The ones used in this example Conditions were:

Extruder, 30 rpm

Window pressure 1.34 · 10 ⁷ Pa

Extruder zone 1 182 ⁰ C

Extruder zone 2 188 ° C

Extruder Zone 3 21O ⁰ C

Nozzle throat 232 ° C

Nozzle body 232 ° C

Vacuum no

Cooling water zone 1 10 ⁰ C

Cooling water zone 2 7.8 ° C

Decrease 61 m / min

The product obtained was opaque and white with a wall thickness of 0.023 cm and a circumference of 25.0 mm.

Example 4

The procedure of Example 1 was repeated using the same polyethylene and 0.3 parts of paraffin oil, 114 parts of talc powder, 0.35 parts Zinc oxide and 0.5 parts Ι, Γ-azobisformamide. The conditions used in this example was:

Extruder, rpm 42

Window pressure 1.6 · 10 ⁷ Pa

Extruder zone 1 166 ° C

Extruder zone 2 177 ° C

Extruder zone 3 188 ° C

Nozzle throat 238 ° C

Nozzle body 238 ° C

Vacuum no

Cooling water zone 1 13 ° C

Cooling water zone 2 10 ° C

Decrease 61 m / min

The product obtained was white and opaque with a rough outer surface. It had a wall thickness of 0.038 mm and a circumference of 24.6 mm.

For this purpose 3 sheets of drawings

Claims (1)

Claims: which is arranged at an angle to the conveying direction of the 1st method for producing a composite fiber mass.
set, structured filter rod for tobacco ^ ____
smoke filter or the like, which contains a fiber mass,
which are enclosed in a tubular envelope
is in which molten thermoplastic material through the extrusion orifice of a
Is the extruder is extruded to form a continuous tubular workpiece, the tube- * -. "... - Shaped workpiece is closed by the mentioned opening ", in which melt-fluid is thermally conveyed away, a cohesive, but chip-plastic material
tension-free cable made of several continuous threads
fibrous filler material in the workpiece and in The invention relates to a method for producing a composite, structured filter rod for tobacco smoke filters or the like, which contains a fiber mass that is inserted in a tubular casing