DE102005017937A1 - Thermal ductile, heat shrinkable multi layer film for the production of thermal formed heat shrinkable hollow packing, comprises carrier, adhesion mediator, oxygen-close barrier and seal layers - Google Patents

Abstract

The mediator layer has a thickness of 20 mu m and is based on ethyl vinyl acetate copolymer having vinyl acetate content of 3-18 mol%. The carrier layer has a thickness of 5-100 mu m and is based on polyethylene, ethyl copolymer, polypropylene and propylene copolymer. The seal layer has a thickness of 5-25 mu m and is based on polyolefins, olefin copolymers, polyalkylmethacrylate and/or alkylmethacrylate copolymers. A heat shrinkage has a stretching ratio of 1:5-1:3. The adjacent layer has a thickness of 50-250 mu m. The barrier layer has a thickness of 5-50 mu m and is based on polyvinylidene chloride copolymer and ethyl/vinylalkohol copolymer. Independent claims are included for: (1) a method of producing a thermal formed heat shrinkable hollow packing; (2) the production of a packing; (3) a packing machine; (4) the production of a packing using heat shrinkable multilayer film; and (5) sealing an upper foil on a hollow packing.

Description

The The invention relates to multilayer films which are thermoformable and simultaneously are heat shrinkable, wherein the heat shrinkability is practically unaffected by thermoforming.

Food become more and more common nowadays offered in plastic packaging containing a packaging tray, in which the food is placed, and a lidding film, with which the packaging tray is sealed include.

The Packaging troughs are usually by thermoforming, usually by deep drawing, from a thermoformable Multi-layer film under the action of heat produced. After introduction of the packaged goods also takes place Sealing the packaging tray with the cover sheet under the action of heat, i. by heat sealing.

It Packaging of this type are known in which the lidding film a heat-shrinkable multilayer film is.

Heat-shrinkable multilayer films are common biaxially oriented and used in the packaging of food, especially perishable foods such as poultry or Fresh meat used, these multilayer films preferably have a gas and / or aroma-dense barrier layer. Heat-shrinkable multilayer films have the property, to their original, not oriented Shrink dimensions, when heated to their softening point. Biaxially oriented Multilayer films are both in the longitudinal and in the transverse direction according to her Stretched production process and often have a heat shrinkability (Shrinkability) of 35% in both longitudinal and also in the transverse direction.

It there is a need for packaging in which not (only) the lidding film, but also the film web from which the packaging tray made is a heat-shrinkable multilayer film is. However, this is difficult to realize. So stands with conventional Packaging materials usually the required to form the packaging tray thermoformability the material of simultaneous heat shrinkability opposite. On the one hand leads the thermoforming conventional Heat-shrinkable multilayer films often for delamination. On the other hand, the thermoforming conventional thermoformable multilayer films to packaging trays, which in the thermoformed areas usually no or only slightly pronounced Thermoshrinkability exhibit.

Packaging materials, which are thermoformable (preferably deep drawable) and at the same time heat shrinkable, have special advantages. With such packaging materials, the Packaged goods be tightly enclosed, especially if both the packaging tray as well as the cover sheet of a heat-shrinkable material is formed. On such packaging materials are special Requirements regarding their thermal and mechanical properties posed. So the shrinking process should be initiated as possible can, after the formation of the packaging tray by thermoforming and the seal with the lidding foil is done in this way a controlled enclosure of the packaging material can be achieved. Accordingly, on the one hand a thermoforming can be done to the packaging tray, without that with the associated heat effect of the shrinking process is initiated. On the other hand, a seal, i. a thermal welding the packaging tray can be done with the lid film, without that with the associated heat effect of the shrinking process is initiated.

The invention has for its object to provide a packaging material which has advantages over the packaging materials of the prior art. In particular, the packaging material should be thermoformed into a packaging tray, preferably deep-drawn, and sealed subsequent to the introduction of the packaging material with the lidding film, without a significant shrinkage of the packaging material has taken place by then. Only then should the shrinking process be able to be initiated by the action of heat, as a result of which the sealed packaging fits tightly against the packaged goods. In this case, after the thermoforming and the heat sealing on the one hand, a sufficient bond adhesion should be ensured and on the other hand also a sufficient heat shrinkage ability be present.

These Task can be solved are made by a thermoformable, preferably deep-drawable multilayer film with a heat shrinkability in longitudinal and in the transverse direction of at least 20% each, wherein the heat shrinkability is not substantially affected by thermoforming. Prefers is the heat shrinkability the multilayer films according to the invention in longitudinal and in each case at least 25%, more preferably at least, in the transverse direction 30%, more preferably at least 35%, most preferably at least 40% and in particular at least 45%.

It was surprising found that multilayer films can be produced which on the one hand thermoformable and even after the thermoforming have sufficient bond strength, and which otherwise are heat shrinkable, the heat effect in the course of thermoforming with suitable devices practical does not affect this property.

"Not essentially influences "or" virtually none Influence "in the sense The description preferably means that the heat shrinkability the multilayer film according to the invention before thermoforming and heat shrinkability the multilayer film according to the invention after thermoforming are only slightly or practically unchanged. Should with the thermoforming a reduction in heat shrinkability go along, so is these preferably less than 10%, more preferably less than 7.5% and in particular less than 5%, relative to the original one Thermoshrinkability the multilayer film.

Prefers is the multilayer film according to the invention heat sealable, preferably the heat shrinkability the multilayer film also by heat sealing substantially is not affected.

• • eine Trägerschicht (T) basierend auf zumindest einem thermoplastischen Polymer;
• • eine Haftvermittlerschicht (H₁) basierend auf zumindest einem Polymer mit einer Schmelzflussindex MFI im Bereich von 0,1 bis 2,0 g/10 min, bestimmt nach DIN ISO 1133 bei 190°C und 2,16 kg, wobei ihre Schichtdicke größer ist als die Schichtdicke zumindest einer der unmittelbar an die Haftvermittlerschicht (H₁) angrenzenden Schichten;
• • ggf. eine sauerstoffdichte Barriereschicht (B);
• • ggf. eine Haftvermittlerschicht (H₂) basierend auf zumindest einem Polymer mit einer Schmelzflussindex MFI im Bereich von 0,1 bis 2,0 g/10 min, bestimmt nach DIN ISO 1133 bei 190°C und 2,16 kg, wobei ihre Schichtdicke größer ist als die Schichtdicke zumindest einer der unmittelbar an die Haftvermittlerschicht (H₂) angrenzenden Schichten; und
• • eine Siegelschicht (S), welche eine der beiden Oberflächenschichten der Mehrschichtfolie bildet und auf zumindest einem thermoplastischen Polymer basiert.

In one embodiment, the invention relates to a thermoformable, preferably deep-drawable, heat-shrinkable multilayer film comprising the following layers:

• A backing layer (T) based on at least one thermoplastic polymer;
• A bonding agent layer (H ₁ ) based on at least one polymer having a melt flow index MFI in the range of 0.1 to 2.0 g / 10 min, determined according to DIN ISO 1133 at 190 ° C and 2.16 kg, wherein their layer thickness is greater is at least one of the layers directly adjacent to the adhesion promoter layer (H ₁ );
• • if necessary, an oxygen-tight barrier layer (B);
• Optionally an adhesion promoter layer (H ₂ ) based on at least one polymer having a melt flow index MFI in the range of 0.1 to 2.0 g / 10 min, determined according to DIN ISO 1133 at 190 ° C and 2.16 kg, with their Layer thickness is greater than the layer thickness of at least one of the immediately adjacent to the adhesive layer (H ₂ ) adjacent layers; and
• A sealing layer (S) which forms one of the two surface layers of the multilayer film and is based on at least one thermoplastic polymer.

The sequence of the individual layers within the multilayer film preferably corresponds to the order of their designation in the above list, ie (T) // (H ₁ ) // (B) // (H ₂ ) // (S). Here, "//" marks the boundary of two adjacent layers. It is not mandatory that two layers separated by "//" immediately follow one another, ie touch each other - it is also possible that further layers are inserted. Multilayer films of the layer sequences (T) // (H ₁ ) // (S) and (T) // (H ₁ ) // (B) // (H ₂ ) // (S) are particularly preferred according to the invention.

The melt flow index MFI of the adhesion promoter layer (H ₁ ) and of the adhesion promoter layer (H ₂ ) present may be the same or different in the range from 0.2 to 1.9 g / 10 min, more preferably 0.3 to 1.8 g / 10 min, more preferably 0.4 to 1.7 g / 10 min, most preferably 0.5 to 1.6 g / 10 min and in particular 0.6 to 1.5 g / 10 min, determined according to DIN ISO 1133 at 190 ° C and 2.16 kg.

In principle, various polymers, copolymers or mixtures thereof are suitable for the adhesion promoter layers (H ₁ ) and optionally (H ₂ ). Preferably, the adhesion promoter layer (H ₁ ) and the optionally present adhesion promoter layer (H ₂ ) are the same or different on an ethylene-vinyl acetate copolymer. It is particularly preferable that the same or different is an ethylene-vinyl acetate copolymer having a vinyl acetate content in the range of 3 to 18 mol .-%, more preferably 5 to 17 mol .-%, most preferably 10 to 16 mol .-% determined according to ASTM E-168. It is possible that the ethylene-vinyl acetate copolymer is further modified. To be mentioned in this connection are acid / acrylate-modified ethylene-vinyl acetate copolymer, anhydride-modified ethylene-vinyl acetate copolymer or a polymer blend at least one of the aforementioned polymers.

In a preferred embodiment, the layer thickness of the adhesion promoter layer (H ₁ ) is in each case greater than the layer thickness of both immediately adjacent to the adhesion promoter layer (H ₁ ) adjacent layers, and / or the layer thickness of the optionally present adhesion promoter layer (H ₂ ) each greater than the layer thickness of both immediately adjacent to the adhesive layer (H ₂ ) adjacent layers. It has surprisingly been found that by suitable choice of the layer thickness of the adhesion promoter layer (H ₁ ) and the possibly present adhesion promoter layer (H ₂ ) the delamination of the layers respectively connected by the adhesion promoter layers in the course of thermoforming can be avoided.

Particularly preferably, the adhesion promoter layer (H ₁ ) and the optionally present adhesion promoter layer (H ₂ ) identically or differently have a layer thickness of at least 20 μm, more preferably at least 25 μm, more preferably at least 30 μm, most preferably at least 35 μm and in particular at least 40 μm on.

In a preferred embodiment the multilayer film according to the invention forms the carrier layer (T) one of the two surface layers the multilayer film.

The carrier layer (T) of the multilayer film according to the invention is preferably based on at least one polyolefin, olefin copolymer, polyester or a mixture thereof. It is preferably at least one polymer selected from the group consisting of polyethylene, ethylene copolymer, polypropylene and propylene copolymer. Preferred polyolefins are polyethylene, in particular polyethylene having a density of at most 0.92 g / cm ³ , polypropylene (PP), ethylene copolymer, in particular ethylene-vinyl acetate copolymer and / or propylene copolymer. Particularly preferably, the carrier layer (T) is based on polypropylene, a propylene copolymer (in particular a propylene random copolymer or a propylene block copolymer) or a mixture thereof.

The backing (T) can be usual Additives, e.g. Anti-blocking agents, antistatic agents and / or lubricants are included.

Preferably is the layer thickness of the carrier layer (T) less than 50%, preferably less than 25% of the total layer thickness the multilayer film according to the invention. Preferably, the carrier layer (T) a layer thickness in the range of 5 to 100 μm, more preferably 6 to 75 μm, more preferably 7 to 50 μm, most preferably 8 to 35 μm and in particular 9 to 15 microns on.

The Sealing layer (S) of the multilayer film of the invention based preferably at least one polymer selected from the group consisting from polyolefins, olefin copolymers, polyalkyl methacrylates, Alkyl methacrylate copolymers, Ionomers, or their mixture.

In a preferred embodiment, the sealant layer (S) is based on at least one polyethylene selected from the group consisting of metallocene-made polyethylene (m-PE), high density polyethylene (HDPE), low density polyethylene (LDPE), and linear low density polyethylene (LLDPE). The sealing layer (S) is particularly preferably based on m-PE, LDPE, LLDPE or a mixture thereof. Preferably, the sealing layer (S) is based on at least one polyethylene, more preferably on a mixture of m-PE (metallocene polyethylene), more preferably with a density equal to or greater than 0.9 g / cm ³ , and a linear low density polyethylene (LLDPE ), preferably having a density equal to or greater than 0.9 g / cm ³ . In a preferred embodiment, the mixture contains 70 to 85 wt.% M-PE, 30 to 15 wt.% LLDPE and optionally up to 5 wt.% Of conventional additives, in each case based on the total weight of the sealing layer (S). The sealing layer (S) can also be based on at least one polypropylene and / or propylene copolymer, preferably a propylene-ethylene copolymer. In a preferred embodiment, the sealing layer (S) based on at least one acrylic acid copolymer, in particular ionomer, ie on an ethylene-acrylic acid copolymer or ethylene-methacrylic acid copolymer, each at least partially, preferably up to 35%, as a salt, preferably as Na or Zn salt are present (preferably Surlyn ^® , for example at least partially as a zinc salt). The sealing temperatures are preferably in the range of 100 ° C to 140 ° C. The melting temperature of the sealing layer (S) is preferably 90 to 140 ° C, more preferably 95 ° C to 130 ° C. The sealing layer (S) can be equipped with the usual excipients such as antistatic agents, lubricants, anti-blocking agents, antifoggants, and / or spacers.

The layer thickness of the sealing layer (S) is preferably at most 25% of the total layer thickness of the multilayer film according to the invention. Preferably, the sealing layer (S) has a layer thickness in the range of 5 to 25 microns, more preferably 7.5 to 20 microns and especially 10 to 20 microns on.

In a preferred embodiment, the multilayer film according to the invention comprises, in addition to the carrier layer (T), the adhesion promoter layer (H ₁ ) and the sealing layer (S), an oxygen-tight barrier layer (B) and / or an adhesion promoter layer (H ₂ ), preferably both an oxygen-tight barrier layer ( B), as well as a primer layer (H ₂ ).

The barrier layer (B) is preferably based on polyvinylidene chloride, a vinylidene chloride copolymer, in particular a vinylidene chloride / methacrylic acid copolymer with up to 10% by weight of methacrylic acid units, or a mixture thereof. Ethylene-vinyl alcohol copolymer (EVOH) is also suitable in principle. The person skilled in suitable methods for measuring the oxygen tightness are known. The permeability to oxygen is preferably at most 70, more preferably at most 50, even more preferably at most 40, most preferably at most 30 and in particular at most 20 [cm ³ m ^-2 d ^-1 bar O ₂ ], determined according to DIN 53380. Preferred is the thickness of Barrier layer selected such that this barrier effect is achieved. It should be noted that due to the thermoforming of the thermoformed areas of the multi-layer film is a reduction in the layer thickness. Preferably, the permeability to oxygen after thermoforming is the above-mentioned values.

In a preferred embodiment the barrier layer (B) has a layer thickness in the region of 5 up to 50 μm, more preferably 7.5 to 25 μm and in particular 9 to 15 microns on.

Basically the multilayer film according to the invention independently in one or more layers additionally customary additives or auxiliaries contain. For varying the sliding properties of the multilayer film may contain at least one layer of lubricant. The lubricants should preferably in the carrier layer (T) and / or the Sealant layer (S) may be included, but may also in addition be contained in at least one of the intermediate layers. Furthermore, the multilayer film in one or more layers conventional stabilizers, Antioxidants, plasticizers, processing aids, UV absorbers, fillers, Anti-flame retardants, Antistatic agents, etc. included. Such substances are those skilled in the art known.

Particularly preferred embodiments of the multilayer film according to the invention are summarized in the following table, wherein the multilayer film has the structure (T) // (H ₁ ) // (B) // (H ₂ ) // (S)

A particularly preferred multilayer film according to the invention has the following structure:

The inventive multilayer film may contain additional layers, for example layers same or differently based on at least one polymer selected from the group consisting of polyolefins, olefin copolymers and polyesters.

The inventive multilayer film can be printed, wherein at least one layer of the multilayer film printed and / or by the addition of additives such as organic or inorganic dyes and pigments are colored can.

In a preferred embodiment is the multilayer film according to the invention transparent. The term "transparent" within the meaning of the invention means that a packaged by the thermoformable multilayer film through with bare Eye can be considered. The transparency is preferred with Help of densitometers quantified. Such methods are the Specialist familiar. Preferred may be used as a measure of transparency the cloudiness measured as optical value. The measurement of the turbidity takes place preferably according to the ASTM test standard D 1003-61 m, Procedure A, after calibration of the measuring instrument with turbidity standards between 0.3 and 34% haze. For example, a Hazemeter of the Fa is suitable as a measuring instrument. Byk-Gardner with integrating sphere integrated in a solid angle of 8 ° to 160 ° Measurement of diffuse light transmission allowed. The multilayer films of the invention preferably have one after the above after thermoforming described turbidity of less than 20%, more preferably less than 18%, more preferably less than 15%, most preferably less than 10% and especially less than 8%. Has preferred the thermoforming on the optical properties of the multilayer films according to the invention no or only minor influence (related to material of the same Strength).

The inventive multilayer film is thermoformable, preferably deep drawable. The term "deep drawing" in the context of the invention defines a material which is heated under suitable conditions Device can be "deep drawn", i. under the action of pressure (and / or vacuum), for example, to a open container, preferably can be formed into a trough. It deals this is a material which has thermoplastic properties so that it is heated Condition is deformable, but sufficient at room temperature dimensional stability such that the shape given by thermoforming (e.g. first is maintained before the shrinking process is initiated by heat.

The inventive multilayer film is heat shrinkable. To it is preferably biaxially oriented, preferably one draw ratio longitudinal (i.e., in the machine direction) from 1: 5 to 1: 3, preferably 1: 3.5 to 1: 4.5 and in the transverse direction from 1: 5 to 1: 3, preferably from 1: 3.5 to 1: 4.5. The layer thickness information in the description are understood as the layer thickness of the respective layer of the multilayer film according to the invention after the longitudinal and transverse orientation.

at the multilayer film according to the invention can to improve their wear and / or puncture resistance one or all layers are networked together. This networking For example, using β-radiation (high-energy electrons) be achieved. The radiation source may be any electron beam generator which ranges from about 150 kV to about 300 kV is working. The irradiation becomes common at a dose up to 60 kGy, with a preferred Dose is in the range of 2 to 15 Mrad.

The inventive multilayer film preferably has a total layer thickness in the range of 50 to 250 microns, more preferably 60 to 200 μm, more preferably 70 to 170 μm, most preferably 80 to 150 and especially 90 to 130 microns.

The Production of the Multilayer Film According to the Invention can as part of a blow, flat film, coating, extrusion, Coextrusion or corresponding coating or laminating method include. Combinations of these methods are possible. such Methods are known in the art. In this context can for example, on A.L. Brody, K.S. Marsh, The Wiley Encyclopedia of Packaging Technology, Wiley-Interscience, 2 edition (1997); W. Soroka, Fumdamentals of Packaging Technology, Institute of Packaging Professionals (1995); J. Nentwig, plastic films, Hanser textbook (2000); and S.E.M. Selke, Understanding Plastics Packaging Technology (Hanser Understanding Books), Hanser Gardner Publications (1997) to get expelled. There are known, customary in the prior art manufacturing plants into consideration. In the case of flat film coextrusion are preferred Plants with rapid cooling, How big Chill rolls, used.

The are polymers used for layer construction of the multilayer film commercially available and adequately described in the art. They usually become for producing the multilayer films according to the invention as pellets or granules, if necessary mixed in conventional mixing equipment, and processed by melting, preferably by means of extruders. If the multilayer film is intended for food packaging, so are all the polymers used for use in food packaging authorized.

The inventive multilayer film is ideal for packaging goods, preferably food, especially preferred from perishable foods. The multilayer film is suitable for example the packaging of foodstuffs such as meat, fish, vegetables, fruits, Dairy products, smoked Prepared meals, cereals, cereals, bread and pastries, but also from other goods, such as. medical products.

One Another object of the invention relates to the use of a thermoformable, heat-shrinkable, preferably the multilayer film according to the invention for producing a packaging or a packaging tray, preferably for a Food. In the manufacture of a packaging is preferred from the multilayer film first by thermoforming a heat-shrinkable packaging tray produced. Because of the special properties of the multilayer film is preferably the heat shrinkability, especially in the thermoformed region of the multilayer film, essentially unaffected by thermoforming.

Further the invention relates to a method for producing a thermoformed, Heat-shrinkable packaging tray comprising the thermoforming of a thermoformable, heat-shrinkable, in particular the multilayer film according to the invention under conditions where the heat shrinkability is not substantially affected in the thermoformed area.

The Thermoforming is preferably carried out as deep drawing. It can be different Deep drawing conditions realized be, for example, from 1: 2 to 1: 5, preferably 1: 4.5. the It is known to a person skilled in the art that the individual layer thickness of the multilayer film can be adapted to the intended thermoforming ratio, so even in the deep-drawn areas afterwards a still sufficient thickness is available.

The The invention also relates to a thermoformed, heat shrinkable packaging tray, which is obtainable by the method described above.

The inventive multilayer film can on conventional Apparatus thermoformed or deep-drawn. It is preferred however, for thermoforming the multilayer film of the invention, i. to Formation of a thermoformed, heat-shrinkable packaging tray, the device described below for the production of deep-drawn Used packaging trays. In that sense, the property is the multilayer film according to the invention, that their heat shrinkability is essentially unaffected by thermoforming, preferably also to a thermoforming with the aid of these below referred to device.

Apparatus for the production of deep-drawn packaging trays:

It is a device for producing deep-drawn Packaging trays made of a film web with a deep-drawing tool, wherein the thermoforming tool is cooled during deep drawing. Preferably the thermoforming tool for the cooling during deep drawing coolant on. Such coolants can for example, cooling lines be, which are located in the area of the thermoforming tool and through the one cooling medium, for example, a cooling liquid or a cooling gas, circulated.

Preferably the device has holding means, so that the film between the holding means and the thermoforming tool is clamped. Preferably the film web is fixed with the holding means before deep drawing he follows. In a preferred embodiment, this retaining means also provided with a coolant, that to the same coolant circuit as the thermoforming tool or connected to another cooling circuit can. As a coolant is particularly suitable for a coolant, for example, in refrigerators and the same application finds.

Preferably is at least one coolant circuit regulated, for example, temperature controlled, so that the thermoforming tool and / or the holding means always a nearly constant temperature having.

Farther Preferably, the device comprises a heating means, more preferably a heating plate, with the film web in particular before Thermoforming is heatable. After the film has been heated and most preferably before deep drawing, the heating medium is restored removed from the film web and / or turned off to overheat avoid the film web and to prevent the cooling of the Thermoforming tool or the holding means are dissipated too much heat got to. Preferably, the heating takes place locally very well, so that only the desired ones Areas and especially not the areas that will be cooled later should be heated. The skilled artisan recognizes that the heating and cooling can be done simultaneously to avoid that certain Areas of the film web during their warming miterwärmen and / or an undesirable one warming of these areas.

In a further preferred embodiment the device has vacuum and / or Pressure medium, with the film web in the thermoforming tool pushed or is drawn in and thereby receives its final form.

The Device is particularly suitable for the manufacture of packaging trays for packaging. she may be part of a packaging machine, preferably one so-called form-fill-seal packaging machine or a so-called Trayformers.

Under Application of the device described above is the film web cooled during deep drawing and thereby a thermoformed packaging tray from a film web produced. Preferably, the film web is doing before deep drawing clamped. Furthermore, the film web is preferred before thermoforming warmed up. Preferably, the warm-up takes place and cooling offset in time, wherein the warming preferably takes place before cooling. Preferably, a surface becomes the film web warmed up and the opposite surface cooled. Deep drawing can be done in any manner known to those skilled in the art. Preferably, however, the deep drawing is done by over- and / or Negative pressure (vacuum).

Preferred embodiments of the device are associated with 1 to 5 explained in more detail. 1 shows the device before deep drawing. 2 shows the heating of the film web. 3 shows the thermoforming of the packaging tray. 4 shows the release of the bracket. 5 shows the resulting packaging tray. The in connection with the 1 to 5 used reference numbers do not apply to the 6 and 7 ,

In 1 the device is shown, which is a thermoforming tool 3 with several thermoforming chambers 10 having. This thermoforming tool is cooled, the cooling in the present case by drilling 2 takes place through which a cooling medium is passed. Above the thermoforming tool 3 is the film web to be deformed 1 between the thermoforming tool 3 and a clamping frame 4 is clamped. The clamping frame 4 is in the present case by means of the bore 5 through which a coolant is passed, also coolable. Above the film web 1 there are heating plates 7 as by the double arrows 6 represented, can be raised or lowered. The person skilled in the art knows that the thermoforming tool 3 is also vertically movable.

2 shows the heating between the clamping frame 4 and the thermoforming tool 3 clamped film web 1 , For that the heating plates were 7 lowered, so that they are preferably in contact with the film web. The film web is warmed up until it has the desired temperature in the region of the hot plate. Preferably, the heating is timed.

Once the film has been heated sufficiently, the heating plates are raised again and the deep drawing of the film web 1 for the production of packaging trays 8th he follows ( 3 ). In the present case, the thermoforming chambers are 10 acted upon with vacuum, with which the film web is deformed as shown. During the entire heating and deep drawing process, the thermoforming tool and the clamping frame are cooled.

One One skilled in the art recognizes that deep-drawing is also possible by means of a stamp or can be done by combination of stamp and vacuum.

Once the packaging trays 8th are deep-drawn ( 4 ), becomes the thermoforming tool 3 lowered, so that the packaging trays 8th from the thermoforming tool 3 removed from the mold. The thermoforming tool will lowered so far that the produced packaging trays can be transported out of the deep drawing area and a new deformation of the film web 1 can be done.

In 5 the finished packaging troughs are shown. By cooling the thermoforming mold are the packing edges 9 and / or the bottom of the package just because the film web shrinks after deep drawing or only very slightly after or during deep drawing. The obtained deep-drawn packaging troughs are therefore heat-shrinkable, their heat-shrinkability being substantially unaffected by thermoforming.

One Another aspect of the invention relates to a thermoformed, heat shrinkable packaging tray, preferably comprising a multilayer film according to the invention or from a multilayer film according to the invention shaped, the heat shrinkability in the thermoformed area in longitudinal and in each case at least 20%, preferably at least, in the transverse direction 25%, more preferably at least 30%, even more preferably at least 35%, most preferably at least 40% and especially at least 45% is.

The thermoformed according to the invention, Heat-shrinkable packaging tray may be advantageous for producing a package, preferably for a Food, to be used. For this purpose, the packaging material is preferred into the thermoformed, heat-shrinkable packaging tray introduced and a preferably heat-shrinkable lid film over the opening of the Packaging trough brought. Subsequently, the heat seal takes place the heat-shrinkable lidding film on the thermoformed, heat-shrinkable packaging tray in conditions where both the heat shrinkability the packaging tray in the thermoformed area as well as the heat shrinkability the lidding film is not affected substantially.

The Invention also relates to a sealed, heat-shrinkable package, which is obtainable by the method steps described above.

Prefers is used for heat sealing the thermoformed, heat shrinkable packaging tray and the preferably heat-shrinkable lidding film uses the sealing device described below. In this Meaning is the property that the heat shrinkability the multi-layer film or thermoformed packaging tray and the Thermoshrinkability the lidding film through the heat seal is not substantially affected, preferably to a heat seal with reference to this sealing device described below.

sealer

It is a sealing device with a lower tool and an upper tool, wherein only the lower tool is heated.

The Tool that extends below the substantially horizontal Film webs is located, is heated. This tool therefore points preferably a heating medium, which is necessary for sealing Temperature available provides. Overall, however, the lower tool of the sealing device can also only partially heated.

Preferably the lower tool is vertically displaceable.

Farther Preferably, the lower tool on sealing jaws, the particular preferably either own heating means or from the lower tool be heated with. In the latter case, it is particularly advantageous when the heater is placed at least near the sealing jaws is.

The Upper tool is preferably arranged vertically displaceable. Further preferably, the upper tool is cooled in order to avoid that It heats up over time and thus an unwanted shrinkage the heat-shrinkable lidding film causes.

The Sealing device is particularly suitable for the production of packaging. It may therefore be part of a packaging machine, preferably a so-called form-fill-seal packaging machine or a so-called Traysealer.

Using the sealing device described above, the heat-shrinkable cover sheet is fixed before sealing. Fixed in this sense means that the respective film web too at least in one direction, preferably transverse to the transport direction of the film can not contract. The fixing of the respective film web can for example be done by the sealing tools themselves, but also by other parts of a packaging machine, such as the transport chains.

In a preferred embodiment the heat input takes place for the Sealing of the heat-shrinkable lidding film opposite side of the packaging. Preferably, the heat input takes place the seal in this procedure from below.

It prevents an unwanted, initiated by the sealing tool Shrinking the heat-shrinkable lidding film he follows. Preferably, the sealing foil facing the cover foil is cooled. These embodiment has the advantage that the lid foil facing tool a Shrinkage of the lid film is not activated unintentionally. It is basically too possible, that the lidding film itself was deep-drawn prior to sealing is.

Preferred embodiments of the sealing device are associated with 6 and 7 explained in more detail. 6 shows the sealing of a shrink film on a thermoformed film web. 7 shows the sealing of a thermoformed shrink film to a non-shrinkable cover sheet. The in connection with the 6 and 7 used reference numbers do not apply to the 1 to 5 ,

6 shows the sealing device 9 made from an upper tool 3 and a lower tool 6 consists. The sealing device is part of a packaging machine. Between the upper and the lower tool are the shrinkable lid foil 2 and the non-shrinkable film web 1 into which packaging troughs 7 have been incorporated by deep drawing, arranged. The foil web 1 is fixed and transported by two chains (not shown) in a packaging machine (not shown). The cover foil 2 gets to the film web 1 sealed to the packaging trays 7 to close. The cover foil 2 is not fixed by chains or the like and is known to be due to its connection to the lower film 1 transported. The lower tool 6 has sealed jaws 4 on, with which the seal of the two slides 1 . 2 he follows. Furthermore, the lower tool has heating elements 5 on, with which the heat required for the sealing is developed. The person skilled in the art recognizes that these heating means do not have to be restricted to the region shown hatched, but that they can fully or partially heat the lower tool. As by the double arrow 8th shown, the lower tool is vertically displaceable. The upper tool is not heated in the present case and is possibly even cooled to avoid that it heats up. The upper tool is arranged vertically displaceable and acts as an abutment for the lower tool. Due to the fact that in the present example the lower tool is heated and there is still a film web between the heated sealing tool and the shrink film or the heat input of the seal is from the side of the package to be produced facing away from the shrink film, there is no danger that the sealing tool will shrink the shrinkage cover film 1 activated.

7 shows the sealing device according to 6 , In the present case, however, the shrinkable film is the film web 1 , in the packaging troughs 7 have been formed. This film web 1 is fixed by two chains (not shown) and transported along a packaging machine, not shown. The cover foil 2 with which the packaging trays 7 is in the present case, a non-shrinkable relatively rigid and thick film web, which is not fixed by the packaging machine. Although in this example the shrinkable film web 1 in direct contact with the heated lower tool 6 stands, there is no uncontrolled by the sealing tool activated shrinkage of the film web 1 because the film web 1 is fixed by the chains of the packaging machine and thus effectively suppresses a shrinkage, at least reduced. The registration of the heat for the seal by the shrinkable comparatively thin film web 1 has the advantage that the seal is faster and that the temperature of the sealing tool can be chosen comparatively low. The warm sealing tool to arrange on the same side as the shrinkable film web is possible because the shrinkable film web 1 has been fixed before sealing.

It can be seen that when combining the in 6 and 7 described cases, ie when sealing a heat-shrinkable packaging tray and a heat-shrinkable lidding film, the sealing device described above can also be used advantageously.

• (a) eine vorstehend beschriebene Vorrichtung zur Herstellung von tiefgezogenen Kunststoffverpackungsmulden aus einer Folienbahn mit einem Tiefziehwerkzeug, wobei das Tiefziehwerkzeug beim Tiefziehen gekühlt ist; und
• (b) eine vorstehend beschriebene Siegelvorrichtung mit einem Unterwerkzeug und Oberwerkzeug, dadurch gekennzeichnet, dass das Unterwerkzeug beheizbar ist.

One aspect of the invention relates to a packaging machine for processing a thermoformable, heat-shrinkable, preferably multi-layer film according to the invention

• (A) an apparatus described above for the production of deep-drawn plastic packaging trays from a film web with a thermoforming tool, wherein the thermoforming tool during deep drawing ge is cool; and
• (B) a sealing device described above with a lower tool and upper tool, characterized in that the lower tool is heatable.

The above separately in connection with the device for manufacturing of deep-drawn plastic packaging troughs or with the sealing device described, preferred embodiments also refer to the packaging machine according to the invention.

• (i) Herstellen einer tiefgezogenen, wärmeschrumpffähigen Verpackungsmulde wie vorstehend beschrieben durch Tiefziehen einer Folienbahn aus einer thermoformbaren, wärmeschrumpffähigen, vorzugsweise der erfindungsgemäßen, Mehrschichtfolie, wobei die Folienbahn beim Tiefziehen gekühlt wird; und
• (ii) Herstellen einer versiegelten, wärmeschrumpffähigen Verpackung wie vorstehend beschrieben durch Siegeln einer wärmeschrumpffähigen Deckelfolie auf die in Schritt (i) erhaltene tiefgezogene, wärmeschrumpffähige Verpackungsmulde, wobei die Deckelfolie und vorzugsweise auch die Verpackungsmulde vor der Siegelung fixiert werden.

A further aspect of the invention relates to a method for producing a packaging from a thermoformable, heat-shrinkable, in particular multilayer film according to the invention, comprising the steps

• (i) producing a deep-drawn, heat-shrinkable packaging tray as described above by deep drawing a film web of a thermoformable, heat-shrinkable, preferably the multilayer film of the invention, wherein the film web is cooled during deep drawing; and
• (ii) producing a sealed, heat-shrinkable package as described above by sealing a heat-shrinkable lidding film to the deep-drawn, heat-shrinkable packaging tray obtained in step (i), wherein the lidding film, and preferably also the packaging tray, are fixed prior to sealing.

The above separately in connection with the device for manufacturing of deep-drawn plastic packaging troughs or with the sealing device described, preferred process variants also relate to this inventive method for the production of a packaging.

With Help the packaging machine described above or by The method described above becomes a sealed, heat-shrinkable package received or is a sealed, heat-shrinkable packaging available, which as a packaging element thermoformed the invention Packaging trough and as another packaging element, a heat-shrinkable lidding film comprises, wherein the two packaging elements edge to each other are sealed. Because neither by the thermoforming nor by the Heat sealing the shrinking process is initiated, the heat shrink properties of Packaging tray and lidding film even after heat sealing essentially unaffected. Both are preferred the heat shrinkability the packaging tray in the thermoformed area as well as the heat shrinkability the lid foil in longitudinal and in the transverse direction at least 20%, preferably at least 25%, more preferably at least 30%, more preferably at least 35%, most preferably at least 40% and in particular at least 45%.

The so obtained inventive sealed, Heat-shrinkable packaging will be final Shrunk so that both the thermoformed packaging tray, and wrap the lidding foil tightly to the packaged goods invest. The shrinking process is initiated by heat, for example in a thermal chamber.

The The invention also relates to a shrunken packaging, which by the above-described shrinkage of the sealed heat-shrinkable package available is.

The displaced by the shrinking process the atmosphere can escape, for example, through a small opening in the packaging, the opening finally is closed. Alternatively, the packaging may be during or be evacuated after sealing.

One Another aspect of the invention relates to a packaging system comprising the multilayer film according to the invention and the packaging machine according to the invention.

Method to exam the shrinkability

to Measurement of shrinkability a film according to the invention will be on the test Foil pattern a crosshair 10 × 10 cm recorded with a foil pen, with a beam in the Machine direction (md), d. H. Extrusion direction and the second Bars of the crosshairs drawn crosswise to the machine direction (cma) becomes. The water bath, in which the foil pattern for 6 sec immersed, has a temperature of 93 ° C.

To 6 sec, the pattern is taken and measured by measuring the shortening of the Crosshair for the respective direction indicated in%.

Claims (46)

Thermoformable, heat-shrinkable multilayer film with a heat shrinkability in longitudinal and in the transverse direction of at least 20% each, wherein the heat shrinkability is not substantially affected by thermoforming. Multilayer film according to claim 1, characterized in that that they are heat sealable is. Thermoformable, heat-shrinkable multilayer film comprising the following layers: a backing layer (T) based on at least one thermoplastic polymer; A bonding agent layer (H ₁ ) based on at least one polymer having a melt flow index MFI in the range of 0.1 to 2.0 g / 10 min, determined according to DIN ISO 1133 at 190 ° C and 2.16 kg, wherein their layer thickness is greater is at least one of the layers directly adjacent to the adhesion promoter layer (H ₁ ); • if necessary, an oxygen-tight barrier layer (B); Optionally an adhesion promoter layer (H ₂ ) based on at least one polymer having a melt flow index MFI in the range of 0.1 to 2.0 g / 10 min, determined according to DIN ISO 1133 at 190 ° C and 2.16 kg, with their Layer thickness is greater than the layer thickness of at least one of the immediately adjacent to the adhesive layer (H ₂ ) adjacent layers; and • a sealing layer (S) which forms one of the two surface layers of the multilayer film and is based on at least one thermoplastic polymer. Multilayer film according to Claim 3, characterized in that the layer thickness of the adhesion promoter layer (H ₁ ) is in each case greater than the layer thickness of both directly adjoining the adhesion promoter layer (H ₁ ) layers and / or that the layer thickness of the adhesion promoter layer (H ₂ ) is greater than the layer thickness of both immediately adjacent to the adhesive layer (H ₂ ) layers. Multilayer film according to Claim 3 or 4, characterized in that the adhesion promoter layer (H ₁ ) and the optionally present adhesion promoter layer (H ₂ ), identically or differently, have a layer thickness of at least 20 μm. Multilayer film according to one of claims 3 to 5, characterized in that it is based on an ethylene-vinyl acetate copolymer based. Multilayer film according to Claim 6, characterized that the ethylene-vinyl acetate copolymer identical or different, a vinyl acetate content in the range of 3 to 18 mol .-%. Multilayer film according to one of claims 3 to 7, characterized in that the carrier layer (T) on at least a polyolefin, olefin copolymer, polyester or a mixture thereof based. Multilayer film according to claim 8, characterized in that that the carrier layer (T) based on at least one polymer selected from the group consisting polyethylene, ethylene copolymer, polypropylene and propylene copolymer. Multilayer film according to one of claims 3 to 9, characterized in that the carrier layer (T) has a layer thickness in the range of 5 to 100 μm having. Multilayer film according to one of claims 3 to 10, characterized in that the sealing layer (S) on at least a polymer based selected from the group consisting of polyolefins, olefin copolymers, Polyalkyl methacrylates, alkyl methacrylate copolymers, ionomers, or their mixture. Multilayer film according to one of claims 3 to 11, characterized in that the sealing layer (S) has a layer thickness in the range of 5 to 25 μm having. Multilayer film according to one of claims 3 to 12, characterized in that it comprises a barrier layer (B), which on polyvinylidene chloride, a vinylidene chloride copolymer or their mixture is based. Multilayer film according to one of claims 3 to 13, characterized in that it comprises a barrier layer (B), which has a layer thickness in the range of 5 to 50 microns. Multilayer film according to one of claims 3 to 14, characterized in that the carrier layer (T) the other of the two surface layers forms. Multilayer film according to one of claims 3 to 15, characterized in that it has a heat shrinkability in longitudinal and in the transverse direction of at least 20% each, wherein the Thermoshrinkability is not substantially affected by thermoforming. Multilayer film according to one of the preceding claims, characterized characterized in that it has a stretching ratio of 1: 5 to 1: 3 in the longitudinal direction and from 1: 5 to 1: 3 in the transverse direction. Multilayer film according to one of the preceding claims, characterized characterized in that the directly adjacent layers are cross-linked with each other. Multilayer film according to one of the preceding claims, characterized characterized in that it has a total layer thickness in the range of 50 to 250 μm having. Use of a thermoformable, heat-shrinkable multilayer film according to one of the claims 1 to 19 for the production of a thermoformed, heat-shrinkable packaging tray. Method for producing a thermoformed, Heat-shrinkable packaging tray comprising the thermoforming of a thermoformable, heat-shrinkable multilayer film according to one of the claims 1 to 19 under conditions where the heat shrinkability is not substantially affected in the thermoformed area. Thermoformed, heat-shrinkable packaging tray comprising a heat-shrinkable multilayer film according to one of the claims 1 to 19, wherein the heat shrinkability in the thermoformed area in longitudinal and in each case at least 20% in the transverse direction. Use of a thermoformed, heat shrinkable packaging tray according to claim 22 for the preparation of a package. Use according to claim 23, characterized that the packaging for a food is. Method for producing a packaging comprising - the procedure according to claim 21 and - the Heat sealing the thus obtained thermoformed, heat-shrinkable packaging tray with a heat-shrinkable lidding foil in conditions where both the heat shrinkability the packaging tray in the thermoformed area as well as the heat shrinkability the lidding film is not affected substantially. Packaging comprising a thermoformed, heat shrinkable packaging tray according to claim 22 and a heat-shrinkable lidding film, where both the heat shrinkability the packaging tray in the thermoformed area as well as the heat shrinkability the lid foil in longitudinal and in the transverse direction is at least 20%. Method of heat shrinkage a package according to claim 26 comprising supplying heat. Packaging machine for processing a multilayer film according to one of the claims 1 to 19 inclusive (a) a device for the production of thermoformed plastic packaging trays from a film web with a thermoforming tool, wherein the thermoforming tool during deep drawing chilled is; and (b) a sealing device with a lower tool and upper tool, characterized in that the lower tool is heated. Packaging machine according to claim 28, characterized that the device for the production of deep-drawn plastic packaging trays coolant having. Packaging machine according to claim 28 or 29, characterized in that in the device for the production of deep-drawn plastic packaging troughs the film web between a holding means and the thermoforming tool can be clamped, wherein the holding means is preferably cooled with coolants. Packaging machine according to one of claims 28 to 30, characterized in that the device for the production Of deep-drawn plastic packaging wells a heating means, preferably a heating plate, with which the film web is heatable, wherein the heating plate is preferably designed as a deep-drawing punch. Packaging machine according to one of claims 28 to 31, characterized in that the device for the production from deep-drawn plastic packaging troughs vacuum and / or pressure medium for deep drawing of the film. Packaging machine according to one of claims 28 to 32, characterized in that in the sealing device, the lower tool Having heating means. Packaging machine according to one of claims 28 to 33, characterized in that in the sealing device, the lower tool is vertically displaceable. Packaging machine according to one of claims 28 to 34, characterized in that the sealing device sealing jaws has, which are preferably heatable. Packaging machine according to one of claims 28 to 35, characterized in that in the sealing device, the upper tool chilled and / or is arranged vertically displaceable. Packaging system comprising a thermoformable, Heat-shrinkable multilayer film according to one of the claims 1 to 19 and a packaging machine according to one of claims 28 to 36th Method for producing a packaging from a thermoformable, heat-shrinkable multilayer film, in particular according to one of claims 1 to 19, comprising the steps (i) making a deep-drawn, heat-shrinkable packaging tray by deep drawing a film web of the multilayer film, wherein the Film web cooled during deep drawing becomes; and (ii) making a sealed, heat-shrinkable package by sealing a heat-shrinkable lidding film on the deep-drawn, heat-shrinkable packaging tray obtained in step (i), wherein the lidding film is fixed before the seal. Method according to claim 38, characterized in that in that in step (i) the film web is clamped before deep-drawing becomes. Method according to claim 38 or 39, characterized that in step (i) the film web is heated prior to deep drawing. Method according to one of claims 38 to 40, characterized that in step (i) a portion of the film web is warmed up and a portion of the film web is cooled. Method according to one of Claims 38 to 41, characterized that in step (i) the film web is deformed by overpressure and / or underpressure becomes. Method according to one of claims 38 to 42, characterized that in step (ii) fixes the cover sheet of sealing tools becomes. Method according to one of Claims 38 to 43, characterized in step (ii), the deep-drawn, heat-shrinkable packaging tray is fixed by transport chains. Method according to one of claims 38 to 44, characterized in step (ii), the sealing foil facing the cover foil chilled becomes. Method according to one of claims 38 to 45, characterized that it includes the step (iii) shrinking in step (ii) the resulting sealed heat-shrinkable package by heat.