DE2317696A1 - Meat extrusion - with coextruded plastic casing - Google Patents

Abstract

A plastic coating material such as a protein is coaxially extruded to surround an extruded meat prod. The extrusion block includes an insulating layer of air which separates the coating and core prior to extrusion so that the meat is not scorched by the high temps. necessary for the coating. A vacuum line is connected to a conduit which terminates at the position where the coating and meat core meet so that gases produced by the contact may be removed to prevent the coating being damaged by trapped gas bubbles. The appts. is typically used to cover a weiner meat emulsion with a wheat gluten coating.

Description

Method and device for the joint extrusion of substances The invention relates to a method and apparatus for extrusion, and more particularly for co-extruding a heat-sensitive material and a hot one plastic wrapping.

It is already known to enclose products in an envelope or film. These products include fresh and dry sausages, especially wiener sausages. Such products have previously been produced by having a shell, for example made of protein or cellulose, extruded and later a meat mass into the casing has filled. In some cases the prepared meat mass or filling is used boiled before placing in the casing, in some cases the casing is filled and then smoked the product.

The joint extrusion of material components is also part of the state of the art. For example, it has recently been found that protein-based edible casings and meat mass can be extruded together. Although one is acceptable Products has received, the properties of the meat mass and the casing material lead to common extrusion to certain difficulties. For example, the for a satisfactory production of a hot plastic protein mass for the extrusion of a casing required high temperatures and can set the meat or dry out or burn the prepared meat mass in the extrusion die. On the other hand, the hot plastic material can be caused by early cooling heat loss to the cold meat can be adversely affected. It is also possible that the filling material or the shell material generates gaseous products, those causing bubbles or pockets to form between the filler material and the envelope resulting in unsightly appearance of the product. For example a hot shell material of a preferred type of water vapor and / or other ~ gaseous Generate fumes.

The object on which the invention is based is to provide a method and to create a device of the type mentioned above, with which these disadvantages essentially eliminated.

This task is accomplished with the extrusion apparatus described in the opening paragraph Kind of an extrusion die for co-extruding any heat sensitive Material and a hot plastic wrapping material and by an extrusion die for coextruding a hot plastic mass and a heat sensitive one Material solved. The mold or extrusion tool includes a first channel 'through the hot plastic mass is extruded, a second channel adjacent the first channel through which the thermosensitive material is extruded, and a thermal barrier disposed between the first channel and the second channel.

The extrusion die for the {g'eme, insame # 'exiru # ieren includes a Housing which delimits an elongated chamber. In the chamber is spaced from the housing a tubular mandrel is arranged, whereby there is a first therebetween Receives channel for extrusion. A tube is at least partially in the mandrel arranged, whereby a heat-insulating gas chamber is delimited between them. The inside of the tube forms the second channel for extrusion.

The device for co-extruding a heat-sensitive Material and a hot plastic mass as a cover for the heat-sensitive Material has an extrusion die, means for feeding the heat-sensitive Materials to the extrusion tool under extrusion pressure and facilities for Feeding the hot plastic wrapping material to the extrusion die under extrusion pressure. The extrusion die for the common extrusion facilities, which delimit a central channel through which the heat-sensitive material extrudes can be, devices that delimit a tubular channel through which the Sheath material can be extruded, this tubular channel coaxially the Surrounds central channel, as well as a thermally insulating device, which is a thermal barrier generated between the central channel and the tubular channel. One embodiment the device for co-extruding meat and protein material as Casing of the meat includes an extrusion die for co-extrusion with a housing which delimits a channel for the extrusion, a first tubular mandrel which is arranged in the channel spaced from the housing, whereby between the housing and the first mandrel a channel for the extrusion of the casing is limited, a second tubular mandrel at least partially in the first tubular mandrel is spaced therefrom, creating a gas channel between the first mandrel and the second mandrel, means for extruding of meat mass through the second tubular mandrel, devices for extruding a hot plastic mass as a shell material through the extrusion channel for the cladding, creating a thin film or layer of hot plastic Mass is applied around the extruded meat, and means for Applying a partial vacuum to the gas duct, creating between the extruded Gaseous products formed from meat and the extruded casing are removed, a tight adhesion between meat and shell is achieved and the moving ones gaseous products create a heat insulating barrier between the first mandrel and the form the second mandrel.

The method according to the invention comprises joint extrusion a thermosensitive material and one surrounding the thermosensitive material hot plastic layer by an extrusion die used for molding respectively.

a spray nozzle and maintaining an insulating barrier between the heat-sensitive material and the hot plastic material in passage through the extrusion die.

A preferred method according to the invention is that a extrudable hot plastic mass is produced that at the same time the hot plastic Mass through an annular nozzle or an annular extrusion die for formation a shell and a filling, consisting of a flowable heat-sensitive Material, placed in the center of the shell that is being formed, with the interior the envelope is substantially filled. Between the hot plastic shell material and an insulating barrier is formed on the heat-sensitive material, while the substances go through the extrusion tool or nozzle. Preferably creates a partial vacuum between the shell and the thermosensitive material on the Extrusion point generated, whereby the formation of gas-filled pockets between the shell and the thermosensitive material is reduced or eliminated. In particular According to the invention, a meat emulsion and a hot plastic protein casing are used extruded together.

Under the term "thermosensitive material11" as used is to understand any edible or immeasurable material obtained by coextruding can be enclosed in a hot plastic filaterial, of which only The exception to this is that the heat-sensitive material is affected by the temperature of the hot plastic material is not adversely affected. This adverse effect can lead to degradation such as charring of the meat this adverse effect from a change in the physical state of solid or semi-solid to liquid, as is the case with jelly and cheese, for example Case is. Typical heat-sensitive substances are meat, cheese, pudding, and jelly various substances that become solid or semi-solid at reduced temperatures.

Any material can be used as the hot plastic shell material become plastic when heated and processed, as in a screw extruder and the production of a satisfactory envelope around the thermosensitive Material permitted. Typical filling materials are protein, cellulose, polyethylene, Polypropylene2 polyvinyl chloride, polyvinylidene chloride and the like. As wrapping materials it is preferred to use simple proteins which cannot be coagulated by heat (US patent application 20,799, corresponding to P ......,).

With reference to the accompanying drawings, the invention is exemplified explained in more detail.

Fig. 1 shows schematically an embodiment of an inventive Device for the joint extrusion of a protein casing and a meat emulsion filling.

Fig. 2 shows the device in longitudinal section.

Fig. 3 shows the device of Fig. # '2 exploded.

Fig. 4 shows a second embodiment of the extrusion tool in longitudinal section.

Fig. 5 shows a third embodiment of an extrusion die in longitudinal section The device 10 shown in Fig. 1 has a nozzle or

an extrusion die 11 for co-extrusion, a feeder 12 for the meat to be extruded (Zuber E-Z-PAC), means 43 for moving an insulating fluid, for example a pump, and a feed 14 for the hot plastic material to be extruded (Wayne extruder).

The extrusion tool 11 shown in Figures 1 to 3 for common extrusion has a rear section ~ <6 "a middle section 17 and a front section 18.

The rear section 16 has a housing part 19 with one provided therein Opening or a channel 20 limited therein, which by a screw connection with a line 21 for the supply of meat from a screw conveyor 12 can be connected is. The rear section 16 also has a plurality of openings 22 in the housing part 19, the purpose of which will be discussed later. A meat tube 23 extends in the housing part 19 and is arranged therein to form a piece with the housing part 19.

The middle section 17 has a housing part 24 with a centrally arranged Opening or a centrally delimited channel 25.

The opening 25 is aligned with the opening 20 in the section 16. The housing part 24 has an opening 26 with a threaded part for engagement with a gas line 27.

The opening 26 thus creates a connection between the gas line 27 and the central opening 25. The housing part --- 24 has a plurality of openings 28, which are aligned with the openings 22 in the rear section 16. The openings 28 can be provided with a thread for receiving screws 29 which connect the rear section 16 to the central section 17. The screws 29 may be suitably thermally insulated from the rear portion 16, for example by isolating intermediate rings 71.

A suitable seal 31 can be placed between the sections 16 and 17 are provided. The seal 31 serves as a thermal barrier between the sections 16 and 17 and prevents the escape of gas between the sections. The middle section 17 also has a plurality of openings 32, the purpose of which will be explained later. The middle section 17 may have a forwardly extending part 33, whose cross-sectional area is reduced. The reduced part 33 can be a recess have, in which an annular seal 34 sits, the front section 18 has a housing part 35 with a centrally arranged opening or a channel 37, which is aligned with the Openings 2o and 25 is aligned in the housing part 21 and 23, respectively. The opening 37 is used as a channel for the materials to be extruded. The opening 37 has a part 38 with an enlarged diameter adjacent to the central section 17, a part 39 with reduced diameter at the front end of section 18 and a central part 30 with an intermediate diameter. The housing part 35 has a thread provided opening 40 for engagement with the conduit 41, which the hot plastic Enclosing material promotes.

A mandrel 42 is arranged in the opening 37 in the section 18.

The mandrel 42 has a tubular portion 43, a shoulder portion 44 and a retaining flange 45. The tubular part 43 has an outer diameter that is slightly is smaller than that of the opening 37 at the front end of the section 18, so that sufficient Space in between for extruding a film or layer of the desired Thickness is created. The shoulder portion 44 has an outer diameter that is substantially is just as large as the diameter of the central part 30 of the opening 37.

The retaining flange 45 has an outer diameter that is substantially is just as large as the enlarged part 38 of the opening 37. The retaining flange 45 may have a recess for receiving an annular seal 46, which is for a sealing engagement between the retaining flange 45 and the front portion 18 cares. The shoulder part 44 and the flange 45 can be machined can be made from a single piece. The mandrel 42 has a pin 50 to the aligned alignment of the leading edge of shoulder 44 with the desired stream of the plastic material. The pin 50 is aligned with the Opening 72 is aligned in the front section 18 'and extends into this opening into it.

The housing part 35 has a multiplicity of openings 47. Screws 48 extend through openings 32 in housing part 24 and are threadedly engaged with the openings 47, whereby the section 17 is attached to the section 18. One A plurality of screws 55 is screwed into the housing part 35, the reason being this will be explained later. The front section 18 has a plurality of heating elements 49 in order to keep the wrapping material in a plastic state. The heating elements 49 can be attached to the outside of section 18 as shown in Fig. 2 is shown. They can also be inserted into suitable openings in the Housing part 35 of section 18 are provided.

The extrusion tool 11 can, as can be seen in FIGS can be assembled by inserting the mandrel 43 into the section 18 so that that the tubular part 43 extends through the opening 37 and that the flange 45 lies in the enlarged part 38 of the opening 37. The tubular part 43 has a diameter that is slightly smaller than that of the opening 37, thereby creating therebetween a channel for the wrapping material is limited. The central portion 17 can be attached to the front section 18 are attached so that the part 33 is in the opening 37 extends and rests against the flange 45. A plurality of screws 48 extend through openings 32 in section 17 and is in openings 47 in section 18 screwed in, whereby the sections are fastened together.

The rear section 16 can be attached in that the meat tube 23 through the opening 25 in section 17 and through the hollow mandrel 42 extends. The outer diameter of the tube 23 is slightly smaller than the inner diameter of the part 43 of the mandrel 42, whereby a gas channel 52 is defined therebetween. That Tube 23 and the part 43 of the mandrel 42 are thus combined so that a heat insulating effective barrier between the cold meat and the hot plastic casing material is formed. The outer diameter of the tube 23 is also slightly smaller than that Diameter of the opening 25, as a result of which a gas channel 53 is delimited. The tube 23 extends preferably slightly over the front edge of the housing part 35, so that the meat is protected from the heat of the housing part 35. A variety of Screw 29 extends through openings 22 'in section 16 and is in openings 28 screwed into section 17, whereby the sections are fastened to one another. The assembled extrusion tool 11 can be connected to the line 21 for the meat supply, the gas line 27 and the supply line 41 for the wrapping material are connected.

The device according to the invention works as follows: the Device lo can be put into operation by using a suitable wrapping material the screw 14 is fed, where it is mixed and processed until there is a is plastic mass. The term "plastic" means that the shell material is continuous and permanent in any direction without tearing as well as forming a uniform Film layer can be extruded.

The extrudable plastic mass can when using protein be a simple protein and a liquid, mostly water. The weight ratio protein to liquid can be about 1: ~ to 6: 1, which is some of the specific proteinaceous substance used.

Various suitable protein raw materials are commercially available or are produced by known processes.

For example, wheat gluten is obtained by separating wheat by means of a functional device that is also available in stores. For the The purposes of the invention are commercially available spray-dried and quick dried wheat gluten. A preferred product is a quick-dried, germinable wheat gluten (Pro-80, General Mills, In.) 1 that has several percent moisture can contain and on a moisture-free basis about 80% germinable wheat gluten, Contains 5 to lo% fat and lo to 15% starch. The raw material preferably contains gluten at least about 80% germinable wheat gluten, the remainder being diluents such as residual fat or liquid, starch, flour or the like. The snail 14 (Brabender, extruder 200; Wayne extruder) presses the mass of the plastic shell material through the tube 41 into the front section 18 of the extrusion die 11. The hot plastic mass enters channel 51 and flows around the tubular part 43 of the mandrel 42. The front edge of the shoulder 44 'can be inclined so that it Distribute the hot plastic mass around the tubular part 43 contributes. The front section 18 is at a temperature by the heating elements 49 preheated, in which the shell material sufficiently plastic for a uniform Current or throughput is. The temperature of section 18 in the case of protein as a wrapper material - ranges from about 135 ° C to 175 ° C (275 to 350) F) what depends on the extrusion speed.

In the channel 52 between the meat pipe 48 and the mandrel 42 can be compressed Gas to be pushed. The gas inflates the extruded sheath 53. The mandrel 42 can can now be centered by adjusting the screws 55 so that you have a sheath with uniform wall thickness. The extruder 12 is meat, for example as Emulsion for wieners or other sausages, fed through the meat pipe 21 in the rear section 16 of the extrusion tool 11 for the common extrusion is pressed. The meat is forcibly in-the meat pipe 23 and out of it on front end of the extrusion tool 11 led out. When the meat from the front At the end of the extrusion tool 11 emerges as a strand, there is a partial vacuum in the anal 52 created. The vacuum should be sufficient to move gaseous products between the to remove extruded meat and the extruded casing and to move between them to promote good adhesion between the two materials. The vacuum should be smaller as the value at which meat and / or casing material is drawn into the channel 52 will. For example, the vacuum can be on the order of 1 to 5 mmHg. The pump or aspirator 13 draws off all gaseous substances that are between -the casing 53 and the meat emulsion 54 are generated, which, for example, water vapor or vapor of another liquid. The passage of these gases through the channel 52 holds an isolating barrier between the mandrel 42 and the meat pipe 23 upright, eliminating overheating or scorching the meat as well premature cooling of the hot plastic mass in channel 51 is prevented. If necessary during operation, the meat pipe 23 to clean, the. rear section 16 can be removed without dismantling '' or an interruption of the extrusion of the plastic mass of the plastic mass is required.

The second embodiment of an extrusion die shown in FIG liA is built similar to the extrusion die 11, with the exception that the Extrusion die 11 A does not have a central section. The extrusion die 11A has a front section 18A with a central channel 37A. Section 18A has one Opening 40A, which connects between the feed pipe 41A for the wrapping material and the central channel 37A. Section 18A can be just like section 18 of the extrusion tool 11 can be built. The mandrel 42A, which is identical to the mandrel 42 is located in the channel 37A.

The extrusion tool liA has a rear portion 16A with a Opening 20A through which the meat emulsion into the extrusion die 11A from the Feed line 21A enters. The rear section 16A also has an opening 26A for receiving conduit 27A through which gaseous substances enter the extrusion die llA can enter or leave this. The meat pipe 23A can be caused by heat or screwing at the rear into section 16A. The meat pipe-23A extends forward through mandrel 42A. The extrusion die 11A is simpler built as the extrusion die 11, but the meat pipe can be used for cleaning cannot be removed without halting production of the casing. The way of working of the extrusion die 11A is essentially the same as that of the extrusion die 11 is identical and therefore does not need to be explained in more detail.

The third embodiment of an extrusion die shown in FIG IB has a rear section 16B, a middle section 17B and a front Section 18B. The rear section 16B has a housing part 1913 with a mit opening 2oB. The opening 20B has a front part 55 and a rear part 56 with reduced diameter. An opening 57 extends rearward and radially outward from part 55 of opening 20B. The opening 57 is used for the extrusion die 1113 to be connected to the feed line 21B for the meat. The meat pipe 23B is hollow with the exception of a one-piece, solidly threaded rod portion 5d extending through rear portion 56 of opening 20B.

A nut 59 secures the tube 23B to section 16B. The meat pipe 23B has a rear opening 61 through which the meat from opening 57 enters. The meat pipe 23B widens radially at its front end 60.

The central section 17B has a housing part 24B with a central channel 25B and a radially extending opening 26B through which gas enters the extrusion tool ilB can enter or leave this. The rear section 16B and the middle section 17B are connected to each other by screws 2913.

The front section 18B has a housing part 35B with a central opening 37B aligned with openings 20B and 25B in housing parts 18B and 24H, respectively is aligned.

The opening 37B has an enlarged rear part 38B and a reduced one front part 3913. A mandrel 42B is arranged in opening 37B. The housing part 35B has a channel 40B which is a source of hot plastic material with the Central opening 37B connects. The housing part 35B has a front part 64 with reduced Cross-section. A heating jacket 62 surrounds the part 64 and is fixed by a clamp 63.

The operation of extrusion die 1113 is essentially to 'that of the extrusion tool 11 is identical and is not explained in more detail, except attaching and removing the meat pipe 23B. Since the meat pipe 23B is a widening front part 60 which is larger than part 39B of the opening 3713, the meat pipe 23B is assembled by pulling it from the front end of the extrusion die 1113 is inserted through openings 3713, 25B and 20B. The mother will then be 59 screwed to the rod part 58 of the Pleischrohr 23B. The pipe 23B is thereby removed that the nut 59 unscrewed and the tube 23B forward from the extrusion tool 1113 is pulled out. This allows the meat pipe 23B to be removed, without having to disassemble sections 16B, 17B and 18B. In addition, can removes the meat tube 23B without interrupting the extrusion of casing material will.

The invention is explained in more detail using the example below. By mixing in a Hobart mixer for 10 to 15 minutes 2000 g of gluten, 1200 g water, 160 ml of 15 normal ammonium hydroxide, 20 g sodium sulfite, 100 g Cab-o-Sil A casing material for sausage is produced with EH 5 and 660 g of glycerine. Cab-o-Sil EH 5 is a fused silica with the following properties: Specific Surface area 390 + 40 m / g (BET), particle size o, oo7 #, remainder at 'a 325 mesh sieve o, o2, density max. 0.037 g / cm3, loss of ignition at 100 ° C on moisture-free Base 2.5 ~, pH value in 4 ~ aqueous dispersion 3.5 to 4.2.

The mixture is in a dispersion mill with three rollers and then in a Wayne extruder with a 1 "diameter (61 cm) screw Length # (24 ") processed.

The extruder runs at 40 rpm and has an extrusion pressure of 105 atmospheres (1500 psig). The operating temperature is 60 ° C, (14o0F). -The wrapping material is Plasticized in the Wayne extruder and an extrusion die with common Extrusion as shown essentially in FIG. The extrusion tool has a temperature of about 1500C (3000F), the gap between the mandrel and the Housing of the front section is about o f 15 mm (0.06 ~). The extruded Foil or film layer has a thickness of about 0.1 to 0.13 mm (0.04 to 0.05 ").

When starting up, air is supplied with a pressure of 0.14 to 0.28 atmospheres (2 to 4 psig) is fed to the extrusion die 11 to collapse the extruded To prevent sheath. A prepared meat mass, as it is traditionally used for wieners made from minced pork, minced Beef and seasoning is made up of the rear section of the extrusion die at a pressure of 5.6 to 7 atmospheres (80 to 100 psig) with a filler device of the Zuber E-Z-PAC type is used. If the meat as a strand from the front Exits the end of the extrusion tool, the pump 13 is switched so that the Channel 52 is placed under a partial vacuum of approximately 3 mm Hg. Then a product can which can be satisfactorily referred to as Wiener can.

Claims (14)

PATENT CLAIMS S device for co-extruding a heat-sensitive Material and a hot plastic mass to encase the heat-sensitive Material, being an extrusion die, means for feeding the heat-sensitive Material to the extrusion line under extrusion pressure and means for feeding it of the hot plastic shell material to the extrusion die under extrusion pressure are provided, characterized by an extrusion tool (11, 11A, 11B) for the # common extrusion with devices that delimit a central channel (23), through which the heat sensitive material (54) can be extruded, means, which delimit a tubular channel (51) through which the casing material (53) extrudes can be, wherein the tubular channel (51) surrounds the central channel (23) coaxially, and with heat-insulating means (52) which have a heat barrier between create the central channel (23) and the tubular channel (51). 2. Apparatus according to claim 1, characterized in that the heat insulating acting devices of the extrusion tool (11, 11A, 1113) for the common Extrude comprising a fluid-conducting channel (52). 3. Apparatus according to claim 1 or 2, characterized in that the fluid-carrying channel (52) of the extrusion tool (11, 11A, 11B) under one Partial vacuum is and with the interface between the hot shell material (53) and communicates with the thermosensitive material (54) at a location where these materials leave the extrusion die (11, 11A, 11B) so that each gaseous material between the shell material (53) and the heat-sensitive material (54) is removed. 4. Device according to one of the preceding claims, characterized in that that the extrusion tool (11, 11A, 1113) for the common extrusion heating devices (49, 62) for heating the tubular duct (51) and the covering material (53). 5. Device according to one of the preceding claims with an extrusion die for co-extruding a hot plastic mass and a heat sensitive one Materials, characterized in that the extrusion tool (11, llA, llB) a first channel (51) through which the hot plastic mass (53) is extruded, a second channel (23) adjacent to the first channel (51) through which the heat-sensitive Material (54) is extruded, and has a thermal barrier (52) interposed between the first channel (51) and the second channel (23) is arranged. 6. Device according to one of the preceding claims, characterized in that that the extrusion die (11, 11A, 1113) for common extrusion has a housing (35) with an elongated chamber (37), a tubular mandrel (42), which in the chamber (37) spaced from the housing (35) to create an intermediate first channel (51) is arranged for the extrusion, and at least partially in the mandrel (42) at a distance from the mandrel (42) arranged tube (23), whereby a gas chamber (52) serving for thermal insulation is delimited therebetween and that Inside the tube (23) forms a second extrusion channel. 7. Device according to one of the preceding claims, characterized in that that means (27) are provided to the gas chamber (52) under a partial vacuum to put. 8. Device according to one of the preceding claims, characterized in that that means (49, 62) are provided to heat the housing (35). 9. Apparatus for co-extruding meat and a protein material characterized as a casing for the meat according to one of the preceding claims 1 by an extrusion die (11, 11A, 11B) for co-extrusion with a Housing (35-), in which an extrusion channel (37) is provided, through a first tubular mandrel (42) which is arranged in the channel (37) at a distance from the housing (35) is, whereby a channel (51) between the housing (35) and the first mandrel (42) to Extrusion of the casing is limited by a second tubular mandrel (23), which is arranged at least partially in the first tubular mandrel (42) at a distance therefrom is, whereby a gas channel (52) between the first mandrel (42) and the second mandrel (23) is limited by devices (12) for extruding the meat mass (54) through the second tubular mandrel (23), through means (14) for extrusion the hot plastic mass (53) of the shell material through the channel (51) for the Extruding the shell, creating a thin film layer of hot plastic mass around the meat (54) exiting the extruder, by means (27) for applying a partial vacuum to the gas channel (52)> whereby gaseous products removed that. between the extruded meat (54) and the extruded Forming wrapping material (53) so that a tight adhesion between the meat and the Shell material is achieved, the moving gaseous products have a heat insulating create effective barrier between the first mandrel (42) and the second mandrel (23) lo. Device according to one of the preceding claims, characterized in that the housing (35) has heating means (49, 62) to keep the protein material in the plastic State while extruding. 11. Method of co-extruding a heat-sensitive Material and a hot plastic mass, in particular with a device according to one of the preceding claims, characterized in that the hot plastic Mass in the form of a hot plastic film layer together with the heat-sensitive one Material 'is extruded through a shaping extrusion tool so that the hot plastic mass surrounds the heat-sensitive material in the form of a film layer, and that an insulating barrier layer between the thermosensitive material and the hot plastic mass as it passes through the extrusion die is maintained. 12. The method according to claim 11, characterized in that the insulating effective barrier is a moving gas stream. 13. The method according to claim 11 or 12, characterized in that the isolating barrier is a zone with a partial vacuum. 14. The method according to any one of claims 11 to 13, characterized in, that gaseous substances between the heat-sensitive material and the hot plastic Film or foil layer are generated when they emerge from the extrusion die and that a tight adhesion between the material and the film layer is achieved, whereby the vacuum removes the gaseous products.