EP1235723A1

EP1235723A1 - Packing drum with a melt adhesive and charging with adhesive

Info

Publication number: EP1235723A1
Application number: EP00990656A
Authority: EP
Inventors: Paul Mrgan; Gerald Petry; Franz-Georg Henrichs
Original assignee: Henkel AG and Co KGaA
Current assignee: Henkel AG and Co KGaA
Priority date: 1999-12-10
Filing date: 2000-12-06
Publication date: 2002-09-04
Anticipated expiration: 2020-12-06
Also published as: CN1407940A; US20020190109A1; WO2001042105A2; WO2001042105A3; ATE270238T1; AU3006601A; EP1235723B1; JP2003516286A; PL355492A1; CA2393800A1; BR0016202A; DE50006981D1; DE10060535A1

Abstract

The invention relates to a packing drum containing a moisture cross-linking melt adhesive (8) which is surrounded by a moisture-tight can comprising a lid (2) made of a composite material, PE- or PP-coated white sheet metal consisting of a casing (1) and a floor. The floor has the form of a moisture-tight flexible membrane (3). The packing drum can in particular be charged in a very economic manner with adhesive.

Description

Containers with a hot melt adhesive and filling the adhesive

The invention relates to a container containing a moisture-crosslinking hotmelt adhesive which is enclosed by a moisture-tight can which has a lid, a jacket made of composite material and a base.

The invention relates in particular to a container which contains a reactive hot melt adhesive, in particular a moisture-crosslinking polyurethane hot melt adhesive. Such adhesives are suitable for particularly high-quality adhesive bindings. They are characterized by very good adhesion properties and excellent strength. They are applied at around 120 ° C and, after cooling, react with the air humidity or the paper to form high-molecular, hardly fusible compounds. The high final strength is achieved through the chemical reaction of free isocyanate groups with surface moisture and with H-active chemical groups on the substrate surfaces. In addition, they are characterized by high chemical resistance, e.g. B. against printing ink oil, as well as high temperature and aging resistance. They require special melting and application equipment and a high processing effort.

These solid, quick-curing hot melt adhesives made of polyurethane are used in the automotive industry, the wood and furniture industry, the graphics industry and bookbinding, the textile industry, the shoe industry, the PE bag production, in the general industry and the electrical and electronics. Examples of these adhesives are the products manufactured by the applicant with the brand names Purmelt, Macroplast QR and Tero-rehm MC. The moisture-curing adhesives are melted by the user and are usually sprayed onto the substrate to be bonded through very fine nozzles. Clogging of the nozzles due to adhesive particles that have already cured with moisture must be avoided, as this would lead to the system coming to a standstill. Therefore, these adhesives must be provided by the manufacturer in almost absolutely moisture-proof packaging, which has a long shelf life without the ingress of moisture, e.g. B. allow humidity from the outside.

It is therefore known to fill the adhesive in a hot, liquid state into a film bag and to seal it airtight and under vacuum after the hot melt adhesive has cooled. The bag consists of an aluminum foil laminated with polyethylene, whereby the aluminum ensures the tightness against air humidity.

The user cuts the film with a knife and pulls the film off the solid product. Undercuts and, in particular, folds in the film are of considerable disadvantage, because in this case the film cannot be removed from the solid hot-melt adhesive block, or only with great difficulty. In addition, the foil bag cannot be completely emptied.

A container of the type mentioned at the outset is known from European patent application EP 0 844 186 A1. The can has a jacket and a base, both of which consist of a composite material and have an internal volume of 0.5 to 5 liters and preferably of 1 to 3 liters. Outside is a moisture-proof layer, e.g. B. made of aluminum or plastic. The inner layer is made of a material that does not adhere to the hot melt adhesive, e.g. B. from polymers based on silicone, PTFE or the like. The middle layer ensures the stability of the container and is made of paper, cardboard or plastic. A rigid lid closes the can thus formed.

However, this container is only suitable for hot melt adhesives that do not have any significant thermal volume contraction when cooled from the liquid state, since otherwise the can would deform. This restriction is also mentioned in the patent application in column 2, lines 36 to 40. If moisture-curing adhesives are to be packaged with a clear volume contraction when cooling from the liquid state, the packaging known from EP 0 844 186 A1 is not suitable. Unless you leave this practically unyielding packaging largely empty, for example only half full. However, this is uneconomical.

In the prior art, the film bags already mentioned are used for this. After the hot melt adhesive has been filled into the foil pouch, it is temporarily sealed to protect it from moisture. When the block of adhesive has reached its final volume after cooling, open the foil bag on the top and seal it again under vacuum. This has the advantage that a possible leakage can be recognized immediately by the user, since in this case the foil bag no longer lies closely against the block of adhesive.

Disadvantages here are the relatively complex filling process and in particular the relatively long period from filling the hot melt adhesive to the final sealing of the film bag. This period is essentially determined by the cooling time.

The object of the invention is therefore to develop a container of the type mentioned at the outset which allows the packaging to be finally closed immediately after the hot and liquid hotmelt adhesive has been filled in, so that the entire filling time is considerably shortened. The container is said to be particularly suitable for hot melt adhesives with a significant thermal volume contraction during cooling. Furthermore, as with the above-mentioned film bag, it should be recognizable to the user whether the container is still airtight and moisture-tight.

This object is achieved according to the invention in the container mentioned at the outset in that the base is designed as a moisture-proof flexible membrane and a bead is preferably integrated in the lid.

For filling, the lid is removed from the can and the hot and liquid hot melt adhesive is poured into the can. The flexible membrane initially curves downwards. After the moisture and airtight When the can is closed with the lid, the filling process is finished. The volume of the hot-melt adhesive decreases during cooling. Because of the dense structure of the can and the lowest possible gas volume in the packaging, the membrane located on the underside of the can and, if applicable, the bead located in the lid bulge inwards, so that a compensation for the volume contraction is created in addition to the volume compensation through the membrane. By looking at the lid, the user can see whether the packaging is still sealed against moisture and air. If the bead is still in the inward position, the packaging is faultless. However, if the can is damaged, the bead can bulge outwards again, which indicates the error.

The behavior of the flexible membrane would not be surprising if the hot filled mass remained a liquid even after cooling and thus the flexibility of the membrane was retained. It is highly surprising, however, that the flexible membrane in the bottom of the packaging is also a suitable means for solids to compensate for the volume contraction when the melt cools, as a rule from far more than 100 ° C. to room temperature (20 ° C.). Because it was feared _^ that the melt solidifies upon impinging on the flexible membrane on the bottom of the package and it is determined, precisely there first and to the greatest extent. The solidified "bottom layer" of the cooled mass of deformation of the flexible membrane into the interior of the packaging would thus stand in the way of itself if the melt in the interior of the package cools and thereby reduces its volume.

It has turned out to be advantageous if the membrane allows a change in the internal volume of the can from 1:50 to 1: 500, in particular 1: 100 to 1: 300, based on the internal volume of the can.

It is also advantageous if the membrane consists of aluminum and has a thickness of 30 to 100 μm. However, a membrane (= flexible layer) made of one or more other materials can also be used. Composites with an Al layer are particularly useful.

A can with an internal volume of 1,000 ml to 20,000 ml is also preferred. In order to prevent the ingress of air humidity from the outside and at the same time to achieve a stable container at only relatively low costs, the jacket preferably consists of cardboard or cardboard on the outside with at least one moisture-proof inner layer. Adhesion of the hot melt adhesive to the inner layer is advantageously prevented if the moisture-tight inner layer has an outer metal layer, in particular an aluminum foil, which thus forms the middle layer of the can jacket, and an inner plastic layer, in particular made of polyethylene or polypropylene. The selection of this plastic layer is based on the requirement to prevent the hot melt adhesive from adhering.

The jacket is preferably designed as a tube wound and welded or glued from a coated cardboard or cardboard web. Such a so-called cardboard wrap can is known per se and allows easy tearing along the adhesive or weld seam.

To glue the individual layers of the moisture-tight can, especially the cardboard wrap can, at high filling temperatures of e.g. Suitable adhesives at 100 to 200 ° C. are expedient, in particular plasticizer-free, highly polymeric dispersion adhesives and 1- or 2-component polyurethane adhesives. For example, Melting of 170 ° C in cardboard wrap cans can be filled without difficulty if they were glued with Adhesin A 7093, an adhesive from Henkel.

The tightness of the jacket against moisture coming in from the outside is guaranteed in a further embodiment with a high degree of security if the moisture-proof lining on the inside of the jacket is pulled over the edges of the cardboard or cardboard web and at the welding or adhesive edges Linings of the adjacent edges lie directly on top of one another in a moisture-tight manner. Such a design of the jacket is for moisture-proof packaging of food and luxury items, for. B. for soluble coffee powder, known from the prior art. However, such an embodiment has not previously been used for packaging moisture-crosslinking hot-melt adhesive. It is also proposed that the lid be made of sheet metal, in particular tinplate. The lid is generally so stable that it does not deform when the hot melt adhesive cools. Only the membrane attached to the underside deforms by arching inwards. All parts in contact with the product are coated with PE or PP.

To protect the membrane, in particular during transport, it is advantageous if an additional cover with a ventilation opening, in particular removable, is attached to the bottom of the can. The vent is required to allow pressure equalization when the diaphragm moves.

Furthermore, the invention also relates to a method for filling a hot melt adhesive into a container of the type according to the invention mentioned above.

In general, the melt which is more than 50 ° C., in particular more than 100 ° C., is filled into the can, which is expediently cooled at least on the bottom. If the can is largely filled, in particular full to the brim, it is sealed airtight and moisture-tight with the lid. If necessary, the not completely filled can with a gas volume of at most 10, in particular at most 5 vol .-%, based on the volume of the filled melt, is previously flushed with a dry protective gas, in particular with nitrogen. The sealed can with the hot melt adhesive is then cooled further to room temperature.

As has already been explained above, particularly economical filling is achieved if the hot liquid hotmelt adhesive is filled into the can, the can is closed with the lid in an airtight and moisture-tight manner, where appropriate flushing beforehand with dry protective gas, in particular nitrogen, and then let the hot melt cool down.

The protective gas must be inert to the reactive groups of the reactive hot melt adhesive. Epoxy, siloxane and in particular isocyanate groups are particularly suitable as reactive groups. They are chemically bound to a thermoplastic polymer, in particular polyurethane, and cause it to crosslink with reactive substances, in particular with water in liquid or gaseous form. Reactive epoxy and polyurethane hot melt adhesives are specifically mentioned. The hot melt adhesives can also be used for sealing, coating, filling and for producing molds.

An exemplary embodiment of the invention is explained in more detail below with reference to drawings. Show it

FIG. 1 shows a perspective view of the can according to the invention from below with the lower cover removed,

FIG. 2 shows a coated cardboard web for the production of the can jacket,

FIG. 3 shows a longitudinal section through the container according to the invention, filled with the hot-melt adhesive, in longitudinal section before the adhesive cools and

Figure 4 is a longitudinal section corresponding to Figure 3, but after the adhesive has cooled.

In all drawings, the same reference symbols have the same meaning and are therefore only explained once, if appropriate.

The can, which can advantageously also be filled automatically, shown in FIG. 1, consists essentially of a wound, internally coated cardboard jacket 1, an upper, tightly closing and stable lid with a bead 2 made of tinplate and a membrane 3 made of aluminum foil which is glued or welded in at the bottom. All parts in contact with the product are PE - or PP coated.

The coating of the cardboard web 4 is shown in Figure 2. The moisture-proof lining 5, which consists of an inner aluminum foil and an outer plastic film, is drawn around the edge 6 of the cardboard web 4, the lining 5 lying inside on the finished can and the edge 5 'lying directly on the corresponding lining of the adjacent winding layer, in order to obtain a moisture-proof can jacket 1. The side 7 of the cardboard web 4, which is only partially visible in FIG. 2, is on the outside of the finished can and is made of cardboard. After the moisture-crosslinking hot melt adhesive 8 has been filled into the can, the can is closed with the lid 2 in an airtight and moisture-tight manner without waiting for the hot melt adhesive 8 to cool down. Due to its weight, the hot melt adhesive 8 presses the membrane 3 outwards, as can be seen from FIG.

When the adhesive 8 cools, it reduces its volume. Since the can is airtight, only the membrane 3 and the bead in the lid can bulge inwards, as shown in FIG. 4. For this purpose, the stable additional cover 9 placed on the underside of the can to protect the membrane 3 has a ventilation opening 10.

As can be seen from FIGS. 3 and 4, the membrane 3 is attached with its edge to the inner lower edge of the jacket 1, in particular welded or glued. The membrane 3 can advantageously be an aluminum foil coated with plastic, the plastic layer being on the inside and allowing the hot melt adhesive 8 to be detached by the user.

One advantage of the container according to the invention is that the filling can take place particularly quickly and, in contrast to the prior art, can also be automated. If the bead in the lid 2 (FIG. 4) points inwards, the user sees that the can is undamaged and that no moisture has penetrated the hot melt adhesive. Undercuts or folds as in the known foil pouch do not occur with this container. If desired, the space 11 above the hot melt adhesive 8, which in a typical 2 kg can has a height of about 2 cm, can be protected with a protective gas, e.g. B. filled with nitrogen. The packaging is particularly easy to remove due to the way the jacket is wrapped. For this purpose, the cover 2 is first cut off from the jacket 1 and then the jacket 1 is peeled off from the adhesive block together with the membrane 3.

The block of adhesive is preferably cylindrical. It is therefore able to roll down an incline.

The 2 kg containers according to the invention are particularly suitable in the wood, shoe and automotive industries and for book production. It is typical of this that the reactive hot melt adhesive is used continuously in large quantities in order to firmly and securely bond paper, cardboard, wood, metals, glass and plastic, in particular elastomers, to one another. It can also be provided that the membrane 3 is connected directly to the additional cover 9. However, the embodiment shown in the drawings is preferred.

LIST OF REFERENCE NUMBERS

coat

Cover with bead

membrane

Cardboard web, 5 'lining

edge

page

Hot melt adhesive additional lid 0 vent 1 room

Claims

claims

1. Container containing a moisture-crosslinking hot melt adhesive (8) which is enclosed by a moisture-tight can, which has a lid (2), a jacket made of composite material (1) and a base, characterized in that the base is flexible as a moisture-proof Membrane (3) is formed.

2. Container according to claim 1, characterized in that the membrane (3) allows a change in the internal volume of the can from 1:50 to 1: 500, in particular from 1: 100 to 1: 300, based on the internal volume of the can.

3. Container according to one of the preceding claims, characterized in that the membrane (3) consists of aluminum.

4. Container according to the preceding claim, characterized in that the membrane (3) has a thickness of 30 to 100 microns.

5. Container according to one of the preceding claims, characterized in that the can has an internal volume of 1000 ml to 3000 ml.

6. Container according to one of the preceding claims, characterized in that the jacket (1) consists of cardboard or cardboard with at least one moisture-proof inner layer (5).

7. Container according to the preceding claim, characterized in that the moisture-proof inner layer (5) has an outer metal layer, in particular an aluminum foil, and an inner plastic layer, in particular made of polyethylene or polypropylene.

8. Container according to claim 6 or 7, characterized in that the jacket (1) as a from a coated cardboard or cardboard web (4) is wound and welded or glued tube.

9. Container according to the preceding claim, characterized in that the moisture-proof lining (5) on the inside of the jacket (1) over the edges (6) of the cardboard or cardboard web (4) is pulled around and on the welding or adhesive edges, the linings (5, 5 ') of the adjacent edges lie directly on top of one another in a moisture-tight manner.

10. Container according to one of the preceding claims, characterized in that the lid (2) consists of sheet metal, in particular tinplate.

11. Container according to one of the preceding claims, characterized in that an additional lid (9) with a vent opening (10), in particular removable, is attached to the bottom of the can.

12. A method for filling a hot melt adhesive into a container according to any one of the preceding claims, characterized in that the hot liquid hot melt adhesive (8) is filled into the can, the can is closed with the lid (2) in an airtight and moisture-tight manner, if appropriate rinsed beforehand with dry protective gas, in particular nitrogen, and then allowed to cool the hot melt adhesive (8).