EP1492665A1

EP1492665A1 - Dry lamination method using non-reactive, monomer-free lamination adhesives

Info

Publication number: EP1492665A1
Application number: EP02745227A
Authority: EP
Inventors: Conrad Henkens; Karl PÖLLMANN
Original assignee: Hueck Folien GmbH and Co KG
Current assignee: Constantia Pirk and Co KG GmbH
Priority date: 2002-04-11
Filing date: 2002-04-11
Publication date: 2005-01-05
Also published as: AU2002316845A1; US20040234792A1; WO2003084742A1

Abstract

The invention relates to flexible film composites comprising two or more layers that are characterized by exceptionally high composite strength and high chemical resistance. The inventive film composites are especially useful for packaging sensitive or aggressive goods and products as they do not release any harmful migration products into the product.

Description

DRY LAMINATING PROCESS WITH NON-REACTIVE, MONOMER-FREE LAMINATING ADHESIVES

The invention relates to flexible film composites, in particular for packaging purposes.

Foil composites are used extensively in packaging technology, since special properties of the packaging can be achieved through a suitable combination of the individual foils.

For example, by using a metal foil, for example an Al foil, light, vapor and aroma-impermeable packaging foils can be produced, e.g. for goods sensitive to light or moisture, which may, however, have a poor resistance to aggressive filling goods.

Plastic films, for example made of thermoplastic materials, such as polypropylene, polyethylene, polyester, polyamide or polyvinyl chloride films are essentially chemically excellent, but usually not sufficiently vapor and aroma impermeable and can only be made largely opaque by additives. Furthermore, plastic films are usually not sufficiently dimensionally stable for a wide variety of packaging purposes.

Composites made of metal with plastic foils or different plastic foils combine the advantages of the individual foil types mentioned above. Mainly 2-layer or 3-layer composites are used for most packaging purposes, but multilayer composites are also conceivable for certain purposes.

Such composites are usually manufactured using reactive adhesives, for example those based on polyurethanes or epoxy resins. However, complete polymerization is not possible during the manufacture and processing of the polyurethane adhesive, so that residual monomers can remain in the adhesive.

From these isocyanate monomers, usually aromatic isocyanates, aromatic amines, which are carcinogenic, can then form in the composite and can migrate into the product. Furthermore, cleavages are possible under unfavorable conditions, which can also lead to aromatic amines.

This is not only disruptive in the case of food packaging, baby and children's food packaging, but also packaging for pharmaceuticals and cosmetics, but is also extremely questionable and risky.

In addition, when reactive adhesive systems are used after the production of the film composite, a certain curing time is necessary, so that the film composite cannot be processed directly, that is, cut, hemmed or deformed. This means a great restriction of economy, high costs, among other things due to the necessary storage time, and also high logistical effort in the production of such film composites.

Another option for producing flexible film composites is the use of an extrusion coating process. However, the disadvantage of this method is that relatively large amounts of laminating adhesive have to be used, with application amounts of approximately 15 g / m ² . Furthermore, the process is relatively complex and, because of the large mechanical and energy expenditure, is not suitable for small batch sizes and is not economically justifiable.

The object of the invention is therefore to provide a flexible two-layer or multilayer film composite which is designed such that the side of the film composite facing the goods to be packaged is selected such that possible migrates from this film of the film composite are harmless and in which no questionable migrates from the film composite itself, ie neither from the laminating agent nor from the films, can get into the packaged goods. Furthermore, the film composite should be able to be further processed immediately after manufacture, that is to say cut, hemmed, deformed and / or printed.

The invention therefore relates to two-layer or multilayer flexible film composites consisting of one or more plastic films and optionally one or more metal films, characterized in that at least the film facing a product to be packaged is a plastic film which is formed by means of a laminating adhesive derived from the composition of the film , which is in the form of a dispersion or solution, is connected in a dry lamination process to one or more plastic and / or metal foils.

The plastic film facing the goods to be packaged can be a

Polyolefin film, for example a polypropylene or polyethylene film or a polyvinyl chloride film. Polypropylene films and

Polyvinyl chloride films used.

Depending on the application, in particular the required stability, tear resistance,

Resistance and the like, these inner films have a thickness of about

50 μm to 120 μm, preferably 12 to 80 μm, particularly preferably 20 μm to

60μm.

This inner film is connected to at least one further plastic or metal film.

Polyester or polyamide films, for example, come into consideration as further plastic films. Depending on the intended use, these foils can have a thickness of 5 to 50 μm, preferably 10 to 25 μm. Aluminum or copper foils are preferably considered as metal foils. These foils can have a thickness of 5 to 150 μm, preferably 7 to 60 μm, particularly preferably 15 to 45 μm.

The inner film is connected to the further films with a laminating adhesive that can be varied according to the composition of the film.

To bond a polypropylene or polyethylene film to a metal film or a polyester or polyamide film, a polypropylene or polyethylene dispersion is used, for example, as a laminating adhesive. This polypropylene dispersion preferably has a viscosity of 50-500 mPa.s and a specific weight of 0.75-0.85 g / cm ³ . The solids content of the polypropylene dispersion is preferably 10 to 20%. The polymer is preferably dispersed in aliphatic, preferably high-boiling, hydrocarbons.

The polyethylene dispersion is a preferably aqueous dispersion with a viscosity of 250 to 1000 mPa.s and a solids content of 10-60%.

For example, solutions of a terpolymer consisting of vinyl chloride, maleic acid and vinyl acetate or vinyl alcohol are used to connect a polyvinyl chloride film to a further plastic film or a metal film.

Examples of suitable solvents are ethyl acetate, optionally in a mixture with acetone.

After removal of the solvent, the lamination adhesive according to the invention preferably has a defined melting range in which the dry lamination then takes place. The corresponding laminating adhesive polymer dispersion or the corresponding laminating adhesive polymer solution is used in an amount of about 2-5 g / m ² .

The improvement of the adhesion between 2 foils of the foil composite can be achieved if necessary by using an adhesion promoter. A commercially available adhesion promoter, for example the A1120 from OSI, is suitable for this. The adhesion promoter is applied in an amount of <0.5 g / m ² , preferably <0.1 g / m ² .

If necessary, this composite of an inner plastic film and a further plastic or metal film, preferably an aluminum film, can also be connected on the outer side facing away from the goods to be packaged with one or more further plastic films, for example polyolefin, polyester or polyamide films.

In this case, the lamination adhesives described above can be used for lamination, if appropriate using an adhesion promoter.

If the film of the above-described two-layer composite on the side facing away from the goods to be packaged is a metal film, in particular an aluminum film, additional plastic and / or metal films can optionally also be laminated on in a conventional manner, for example using reactive adhesive systems, since the metal foil forms a barrier layer against the migration of undesirable monomer components and / or additives and / or fillers and additives of the adhesive system.

However, the lamination system according to the invention is preferably used. Another object of the invention is a process for the production of the two-layer or multilayer flexible film composites according to the invention, which is characterized in that the dispersion or the solution of the laminating adhesive is applied to the plastic or metal film provided, and then the dispersing agent in a drying tunnel. or solvent is completely evaporated, whereupon the film is connected in a laminating unit at the melting temperature of the dry laminating agent under pressure to the second plastic or metal foil and, if necessary, in further steps this second plastic or metal foil with further plastic and / or Metal foils is connected.

Another object of the invention is a device for performing the method according to the invention, characterized in that the device from a roll-off station 1 for providing the first film, an applicator 2 for applying the solution or dispersion of the laminating agent, a drying tunnel 3, in which the Laminating adhesive is dried until solvent-free, there is a second unwinding station 4 for providing the second film, a laminating station 5 for connecting the first to the second film and subsequent further processing units 6.

These further processing units can be, for example, a roll-up station for rolling up the composite, a cutting or seaming station, a printing station or also a further device for producing a multilayer composite.

Such a device is shown schematically in FIG. 1, a reeling station being shown here as a further processing unit 6.

If necessary, the second plastic film can be treated with an adhesion promoter. If the further foils are laminated on in accordance with the method according to the invention, any further foil may additionally be treated with an adhesion promoter. When using other lamination systems, for example reactive systems for producing the connection of a two-layer flexible film composite produced by the method according to the invention with further plastic and / or metal foils, the treatment of the further laminated foils with the adhesion promoter may optionally be omitted.

To carry out the method, the first film, for example an aluminum film, is provided by the unwinding station 1 and a solution or dispersion of the laminating adhesive is applied in the application unit 2. The application can be carried out in any conventional manner by means of brushing, spraying, printing (gravure, flexo or screen printing) or roller application techniques

In the drying duct 3, the laminating adhesive is used depending on the solvent or Dispersant dried at elevated temperature. Subsequently, the Al film treated in this way is laminated in the laminating unit 5 at elevated temperature, for example approximately at 110-200 ° C. under a pressure of approximately 20-45 N / cm, to a plastic film provided by the unwinding station 4.

The web speed can be 40-180 m / min, preferably 80-140 m / min.

The temperature in the laminating station is preferably about 120-190 ° C. the pressure about 25 - 40 N / cm.

After the laminating station, the flexible film composite is ready and can be processed immediately. No further curing, reaction or storage times are required. The flexible film composite can then be cut, hemmed or deformed immediately.

The film composite can then, for example, be printed immediately or otherwise refined using a known printing process. However, it is also possible to supply a corresponding film in the laminating unit in a printed or finished state, although care must be taken that the printing inks used are sufficiently heat-resistant so that they are not impaired by the temperatures in the laminating unit that depend on the laminating agent used.

The flexible film composite is particularly characterized by high bond strengths, complete freedom from harmful migrants, excellent chemical resistance and excellent ductility. Furthermore, the composites can be sterilized, depending on the plastic films used.

The flexible film composites according to the invention have substrate-independent bond strengths of> 6 N / 15 mm (cohesive failure), preferably> 8 N / 15 mm (according to DIN 53357).

The flexible film composite can be deep-drawn, for example, for the production of blister packs, the deep-drawing ability being significantly better than the deep-drawing ability of the previously known flexible film composite, i.e. the composite can be drawn deeper and more precisely than the previously known flexible film composites without impairing the properties of the composite.

Due to their properties described above, the flexible film composites according to the invention are particularly suitable for use in packaging in the food, feed or pharmaceutical or cosmetics industries, as packaging in the construction industry, in the chemical industry, but also as packaging for cleaning agents, for gardening and Agricultural needs, such as soil, fertilizer, mulch or agricultural chemicals. Examples of such applications in the food industry are milk and dairy products, beverages, in particular also fruit juice beverages, vegetables and salads, in particular as finished products, for example in marinades or with additives for increasing the shelf life; in the feed industry packaging for pet food, dry feed or wet feed and feed supplements; as well as for animal care products; in the pharmaceutical industry, packaging for medicines, tablets, dragees, ointments, gels, emulsions, enemas, dose packs for liquid pharmaceutical formulations, such as juices and drops and the like; in the cosmetics industry, packaging for body and face, cleaning and care products and sample packs of liquid, creamy or emulsified, foam or solid products such as shower baths, shampoos, lotions and the like; in the construction industry, packaging for solid, powdery, liquid or tough building materials or building additives, such as lime, cement, plasticizers, hardening retardants, mold control agents and the like; in the chemical industry as packaging for liquid and solid synthesis starting materials, catalysts, fertilizers, crop protection agents, acidic or basic solutions, cleaning agents and the like; Furthermore, the film composites according to the invention can be used as technical films, for example also as packaging for battery acid and the like.

This enumeration of the possible uses of the flexible film composites according to the invention is not taxative and is only exemplary.

Examples:

Example 1 :

A polypropylene dispersion in Isopar M (C9-C12-i-alkanes) with a solids content of 12% and a viscosity of 120 mPa.s was applied to an aluminum foil with a thickness of 20 μm as laminating adhesive.

The laminating adhesive was dried in the drying tunnel at 180 ° C. In the laminating station, the aluminum foil treated in this way was brought together with a polypropylene foil with a thickness of 20 μm and laminated under a pressure of 20 N / cm and at a temperature of 180 ° C. The web speed was 140 m / min.

The flexible film composite produced in this way was then rolled up and samples were taken to determine the bond strength and the migrate. The flexible film composite has a bond strength of 12 N / 15mm according to (DIN 53 357). The migrates of the composite were determined by gas chromatography in dodecane (60 ° C., 2 days) against polypropylene film as a reference. No qualitative differences were found.

Example 2:

A polyester film with a thickness of 15 μm was 0.08 g / m ² of

Adhesion promoter A1120 (from OSI) coated and then with a

Laminating adhesive consisting of a polypropylene dispersion in Isopar M with a solids content of 10% and a viscosity of 70 mPa.s coated. The laminating adhesive was then added to the drying tunnel

Dried 180 ° C.

In the laminating plant, the polyester film treated in this way was coated with a

Example 1 produced composite film merged and at one

Laminated temperature of 180 ° C under a pressure of 20 N / cm.

The finished 3-layer flexible film composite had a bond strength of 7N / 15mm between the polyester and aluminum layers. The following composites were produced in an analogous manner: Table 1:

The following bond strengths were measured: Table 2:

Claims

claims

1) 2- or multi-layer flexible film composites consisting of one or more plastic films and optionally one or more metal films, characterized in that at least the film facing the goods to be packaged is a plastic film which by means of a laminating adhesive derived from the composition of the film, which in Form is a dispersion or solution, is connected in a dry lamination process with one or more plastic and / or metal foils.

2) 2- or multi-layer flexible film composites according to claim 1, characterized in that the plastic film facing the goods to be packaged consists of polyethylene, polypropylene or PVC.

3) 2- or multilayer flexible film composites according to one of claims 1 or 2, characterized in that an aluminum foil or a copper foil is used as the metal foil.

4) 2- or multi-layer flexible film composites according to one of claims 1 to 3, characterized in that the plastic film facing away from the goods to be packed consists of polyamide or polyester.

5) 2- or multi-layer flexible film composites according to one of claims 1 to 4, characterized in that at least one film of the film composite is printed. 6) 2- or multilayer film composites according to one of claims 1 to 5, characterized in that the plastic film facing the goods to be packaged has a thickness of 5 to 120 microns.

7) Process for producing the two-layer or multilayer flexible film composites according to the invention, characterized in that the dispersion or the solution of the laminating adhesive is applied to the plastic or metal film provided, and then the dispersant or solvent is completely evaporated in a drying channel, whereupon the film is connected to the second plastic or metal foil under pressure at the melting temperature of the dry laminating agent and, if necessary, this second plastic or metal foil is connected to further plastic and / or metal foils in further steps.

8) Method according to claim 7, characterized in that the laminating adhesive is applied in an amount of 2- 5 g / m ² .

9) Method according to one of claims 7 or 8, characterized in that an adhesion promoter is applied to improve the adhesion.

10) Method according to claim 9, characterized in that the adhesion promoter is applied in an amount of <0.1 g / m ² .

11) Method according to one of claims 7 to 10, characterized in that the composite is produced in the laminating unit at a temperature of 110-200 ° C under a pressure of 25 to 40 N / cm.

12) Method according to one of claims 7 to 11, characterized in that the web speed in the laminating unit is 40 to 180 m / min. 13) Method according to one of claims 7 to 12, characterized in that the film composite is then further processed inline, in particular printed and / or cut and / or hemmed and / or deformed.

14) Method according to one of claims 7 to 12, characterized in that the film composite is then further processed in separate work steps, in particular printed and / or deformed and / or cut and / or hemmed.

15) Device for carrying out the method according to the invention, characterized in that the device consists of a roll-off station 1 for providing the first film, an applicator 2 for applying the solution or dispersion of the laminating adhesive, a drying channel 3 in which the laminating adhesive dries until it is solvent-free a second unwind station 4 for providing the second film, a laminating station 5 for connecting the first to the second film and subsequent further processing units 6.

16) Use of the flexible film composites according to one of claims 1 to 6, as packaging materials in the food, feed, pharmaceutical or cosmetics industry, for aggressive technical or agricultural products, in the fertilizer and

Pesticide industry, building materials industry and chemical industry.