WO2000034129A1

WO2000034129A1 - A process for packaging pressure-sensitive hotmelt adhesive

Info

Publication number: WO2000034129A1
Application number: PCT/US1999/027920
Authority: WO
Inventors: Gary Stufflebeme; Michael Czmok; Carlos-Colameo Motta; Juan Carlos Figueroa
Original assignee: Henkel Kommanditgesellschaft Auf Atkien
Priority date: 1998-12-10
Filing date: 1999-12-09
Publication date: 2000-06-15
Also published as: AU2347700A; AR021622A1

Abstract

Separate portions of a pressure-sensitive hotmelt adhesive are produced and packed in a bag of plastic film which is suitable for melting together with the hotmelt adhesive and which has no surface tackiness at normal storage temperatures. According to the invention, the temperature of the separate portions is so low that the portions have substantially no surface tackiness. The temperature of the portions is kept sufficiently low to avoid suface tackiness until the portions have been bagged. A distinctly improved process is provided, little or no air being trapped in the film pack. The process is also very reliable in operation, easy to handle and easy to automate.

Description

A PROCESS FOR PACKAGING PRESSURE-SENSITIVE HOTMELT ADHESIVE

Field of the Invention

This invention relates to a process for packaging pressure-sensitive hotmelt adhesive in which separate portions of the hotmelt adhesive are produced and packed in a bag of plastic film which is suitable for melting together with the hotmelt adhesive and which has no surface tackiness at normal storage temperatures, more particularly at temperatures of up to 50°C.

Background of the Invention

Hotmelt adhesives are solventless adhesives which are capable of effectively wetting surfaces of materials after heating and in the liquid state and of firmly adhering to those surfaces after cooling and solidifying. They generally consist of a mixture of substances which form the adhesive, the cohesive and the additive component.

In the production process, the components are melted together, mixed and then made up. Particular difficulties in regard to making-up, which are discussed in more detail hereinafter, are presented by the so-called pressure- sensitive hotmelt adhesives, i.e. hotmelt adhesives which are permanently tacky, even at room temperature. Merely by pressing onto a surface to be bonded, they adhere to that surface without having to be heated or melted. The pressure-sensitive hotmelts used in industry are supplied in the form of large blocks which are heated in melting pans which in turn feed adhesive pumps and nozzles in order to apply the adhesives to laps of packing boxes, for the production of furniture, disposable diapers for infants, feminine hygiene products, doctor coats, textiles for surgeons and the like. The hotmelt adhesive is used as a structural adhesive for articles such as these, especially for disposable articles. Application of the hotmelt adhesives can be carried out by various application systems depending on the nature of the article to be produced and the surfaces to be bonded.

However, the large pressure-sensitive hotmelt blocks are difficult to handle on account of their weight and their high surface tackiness and, moreover, take a relatively long time to melt.

Several alternative proposals to simplify the use of pressure-sensitive hotmelts are known. Firstly, it has been proposed to pour the molten adhesive into a sausage-like container (cf. for example DE 24 13 575 A1).

The container can even be filled at an adhesive temperature higher than the softening temperature of the container providing the container is externally cooled with water or immersed in water during filling. The container is made of plastic or a plastic composition which is soluble in and compatible with the molten adhesive.

The advantage of wrapping individual portions in a film such as this is that the individual "sausages" do not adhere to one another which is also known as blocking and which leads to very serious difficulties in the case of pressure-sensitive hotmelts, the so-called pressure-sensitive hotmelts, which are tacky even at room temperature.

One disadvantage lies in the high cost of the necessary equipment because this process requires a specially modernized plant for the production of sausages. Another disadvantage of the process known from DE 24 13575 A1 lies in the danger that the hotmelt adhesive wrapped in the film contains air bubbles or air interstices. The air can be present inside the adhesive or even at the ends of the adhesive portions. The adverse effects of the air component are explained in more detail hereinafter.

According to another proposal, several homogeneous portions of the adhesive composition are prepared, the portions are sufficiently hardened and are then formed into a batch which is substantially completely surrounded with a plastic film (German Utility Model DE 91 16 662 U1 , H.B. Fuller Licensing & Financing, Inc.). The portions may assume the form of small "pillows" which are wrapped in a film, the pillows in turn being packed in bags of normal size (in the kg range). The plastic film of which the individual wrappings and the bag itself consists is designed to melt together with the adhesive composition and to be miscible with the molten adhesive composition, the nature and quantity of the plastic film being selected so that, on incorporation in the adhesive composition, they do not adversely affect its properties.

The process steps of forming the portions into a batch and wrapping the individual pillows are necessary because otherwise the pillows would adhere to one another (blocking) on their way to the bagging station. This is because, on account of their weight, they tend to apply pressure to one another, to flow (cold flow) and hence to adhere to one another because hotmelt adhesives are generally relatively low-melting thermoplastic compositions. Since the tendency of the hotmelt adhesive to block prevents the pillows simply being poured into bags, the portions have to be hardened and wrapped in the plastic film.

Another disadvantage is that the portions have to be homogeneous. This is because the uniformity of the pillow size leads to a relatively large amount of air in the filled bags. This air component cannot be readily and completely removed in the user's melting pan and passes with the molten hotmelt adhesive to the application nozzle where it causes uneven application of the adhesive to the substrate. Thus, after the troublesome air has escaped, a particularly large amount of molten adhesive is released from the nozzle and, for example when applied to the plastic film of a disposable diaper, can melt a hole in the film, thus damaging the diaper. In addition, a process for granulating hotmelt adhesives is known.

However, the hotmelt adhesives used have no surface tackiness at room temperature. Free-flowing granules of the adhesive are obtained as follows from the melt.

The molten adhesive is transported through an extruder or a melt pump to a heated extrusion die where it is forced through bores arranged in a circle.

A stream of water flows past the outlet side of the extrusion die. Rotating blades arranged on this side of the extrusion die cut the strands of adhesive issuing from the extrusion die and surface-hardened by the stream of water. The adhesive granules are transported by the stream of water to a preliminary draining stage where most of the water is separated from the granules. The residual water remaining is then removed from the granules in a dryer. An underwater granulator suitable for this known process is described in DE 37 02 841 C2 (Gala Industries, Inc.). In the final stage of the process, the dry granules, which are at about room temperature, are collected in a container or directly packed in cardboard boxes.

The known process is unsuitable for the granulation of pressure- sensitive hotmelt because the surface tackiness of the granules formed makes them adhere to one another in the drying stage which would make packaging or making up impossible.

Although it would be possible in principle to coat the granules with a release agent before they are packed in boxes, the granules would block - despite their coating - at the high storage temperatures often encountered in practice and under the pressure prevailing during packaging. Another disadvantage is the presence of the release agent which, in general, adversely affects the performance properties of the pressure-sensitive hotmelt and, above all, its adhesive strength.

Summary of the Invention

The problem addressed by the invention was distinctly to improve the process for packaging pressure-sensitive hotmelt adhesive known from German Utility Model DE 91 16 662 U1 (H.B. Fuller Licensing & Financing, Inc.), more particularly in regard to the process step where the portions are formed into a batch. In addition, no air would be trapped in the film wrapping.

The process according to the invention would also be very reliable in operation, easy to handle and easy to automate. Moreover, the process would be universally usable for all pressure-sensitive hotmelts and would only require limited capital investment. According to the invention, the solution to the problem stated above is characterized in that the temperature of the separate portions is so low that the portions have substantially no surface tackiness and in that the temperature of the portions is kept sufficiently low to avoid surface tackiness until the portions have been bagged. According to the invention, maintaining a low temperature of the granules for a certain time, i.e. until the granules have been bagged, is crucially important. Relatively small granules are advantageous in this regard because they can be rapidly cooled to the desired temperature. The upper temperature limit for any pressure-sensitive hotmelt adhesive can readily be determined by tests.

It is expressly pointed out that all quantitative data in the present Application - except for the Examples - are meant to be interpreted in the sense of "approximately".

Detailed Description of the Invention

The following advantages are achieved by the process according to the invention. The machinery for carrying out the process according to the invention consists of standard commercial units, namely a mixer for the molten composition, an adjoining unit for making the separate portions of the hotmelt adhesive and a bagging unit. In contrast to the known process mentioned above for filling sausage-like containers with the pressure-sensitive hotmelt adhesive, there is no need to construct a special new plant or to modify similar plants. It is sufficient to make up the machinery from conventional units, as will be explained in more detail hereinafter.

Carrying out the process with standard commercial units is operationally very reliable, easy to handle and easy to automate. The process may be used for packaging all types of hotmelt adhesives. The capital investment required for a machine suitable for carrying out the process according to the invention is lower than for a machine for packaging the hotmelt adhesives in sausage-like containers.

In contrast to the known process, the individual portions do not have to be kept separate during their solidification. There is also no need to combine the batch of portions intended for one bag before they are bagged because the portions are free-flowing granules, at least for the period until they are bagged. The individual portions do not have to be provided with an abhesive substance, for example a non-tacky film, which could adversely influence the adhesive composition and its performance properties. In contrast to the process according to DE 91 16 662 U1 , the percentage of plastic film wrapping in the overall volume of the packaged hotmelt adhesive is considerably lower because the individual small portions no longer have to be wrapped in a plastic film before they are bagged. Another advantage over the known process is that the amount of air present in the filled bag can be significantly reduced so that the above-mentioned difficulties which users encountered when applying the hotmelt adhesive, i.e. uneven discharge of the adhesive from the application nozzle with the unwanted consequences mentioned, are avoided. If the individual portions have a range of irregular shapes and sizes, better packing density and less inclusion of air are achieved. The portions can assume the form of short cylindrical granules, tablets, pellets, prills, fine powder or the like.

Finally, another advantage of the process according to the invention is the increased packaging rate of the hotmelt adhesive.

Suitable Hotmelt Adhesives and Bag Materials

The process according to the invention is suitable for packaging almost any type of hotmelt adhesive composition providing it is compatible with the material selected for the bag so that the bag is able to dissolve readily in the molten hotmelt adhesive at the user. Olefinic films, such as polyethylene and poly-(ethylene-co-vinyl-acetate), are compatible with aliphatic and aromatic hydrocarbon hotmelt adhesives. Commercial hotmelt adhesive compositions of this type contain hotmelt adhesives based on ethylene/vinyl acetate copolymer and amorphous propyiene-α-olefin (APAO). Any hotmelt adhesives based on styrene/butadiene/styrene (SBS) A-B-A-B-A multiblock copolymers, structural hotmelt adhesives based on styrene/butadiene/styrene (SB)_n radial copolymers and structural hotmelt adhesives based on styrene/isoprene/styrene (SIS) A-B-A copolymers may also be packaged. Polyamide-based hotmelt adhesives may also be packaged by the process according to the invention, in which case a bag of a corresponding polyamide film compatible with the hotmelt adhesive during their simultaneous melting is preferably used.

For example, the packaging process according to the invention can be applied to hotmelt adhesives which have been produced from synthetic resins and gums such as polyethylene, polypropylene, polyurethane, polyacrylate, polyvinyl acetate, copolymers of ethylene and vinyl acetate and polyvinyl alcohol. The process according to the invention is of particular advantage for hotmelt adhesives with serious handling problems, for example for the above- mentioned PSA hotmelts which are still tacky even at room temperature. Special examples include hotmelt adhesives produced from the following components:

1) elastic polymers, such as block copolymers, for example styrene/butadiene, styrene/butadiene/styrene, styrene/isoprene/styrene, styrene/ethylene/butylene/styrene, styrene/ethylene/propylene/styrene;

2) ethylene/vinyl acetate polymers, other ethylene esters and copolymers, for example ethylene/methacrylate, ethylene/n-butyl acrylate and ethylene/acrylic acid;

3) polyolefins, such as polyethylene and polypropylene; 4) polyvinyl acetate and copolymers therewith;

5) polyacrylates;

6) polyamides;

7) polyesters;

8) polyvinyl alcohols and copolymers therewith; 9) polyurethanes;

10) polystyrenes;

11 ) polyepoxides;

12) copolymers of vinyl monomers and polyalkylene oxide polymers;

13) resins prepared from aldehydes such as phenol aldehyde, urea aldehyde, melamine aldehyde and the like.

Components for improving adhesion (tackifiers), plasticizers (flexibilizers), wax components, diluents, stabilizers, antioxidants, dyes and fillers may also be present. Examples of adhesion-improving components are

1) natural and modified resins,

2) polyterpene resins, 3) phenol-modified hydrocarbon resins,

4) aliphatic and aromatic hydrocarbon resins,

5) phthalate esters and

6) hydrogenated hydrocarbons, hydrogenated resins and hydrogenated resin esters.

Examples of diluents are liquid polybutene or polypropylene, petroleum waxes, such as paraffin and microcrystalline waxes, semiliquid polyethylene, hydrogenated animal, fish and vegetable fats, mineral oil and synthetic waxes and also hydrocarbon oils.

Examples of the other additives can be found in the literature. As already mentioned, the choice of the material for the bags used is determined by the requirement that the film should be completely and homogeneously miscible with the hotmelt adhesive in the user's melting pan and should not adversely affect the properties of the hotmelt adhesive after mixing beyond commercially acceptable limits. Since the bag is sealed preferably by welding after it has been filled, the film used should also lend itself to welding.

Suitable films may be formed from ethylene-based polymers, such as ethylene/vinyl acetate copolymers, ethylene/acrylate copolymers, ethylene/methacrylate copolymers, ethylene/methyl acrylate copolymers, ethylene/methyl methacrylate copolymers, HD and LD polyethylenes, polyethylene blends and chemically modified polyethylenes, copolymers of ethylene and mono- or di-unsaturated C_1-6 monomers, polyamides, polybutadienes, polyesters, such as polyethylene terephthalate (PET), polybutylene terephthalate, etc.; thermoplastic polycarbonates, atactic poly-α- olefins, including atactic polypropylene, thermoplastic polyacrylamides, polyacrylonitriles, copolymers of acrylonitrile and other monomers, such as butadiene, styrene, etc., polymethylpentenes, polyphenylene sulfides, aromatic or aliphatic polyurethanes, styrene/acrylonitrile copolymers, acrylonitrile/butadiene/styrene copolymers, styrene/butadiene rubber, and/or acrylonitrile/butadiene/styrene elastomers.

In a preferred embodiment, the film is comprised of a polymer selected from the group which consists of polyethylenes, ethylene/vinyl acetate copolymers and mixtures thereof.

In a particularly preferred embodiment, the polymer comprising the film is LD (low-density) polyethylene or ethylene/vinyl acetate copolymer which contains up to 10% by weight of vinyl acetate in polymerized form and, in particular, has a melting point below 120°C.

The film may contain, in addition to the aforementioned polymers, any of the conventional plastic additives known in the art such as, for example, plasticizers, stabilizers, antioxidants, dyes, fillers and the like. In addition, the weight of the bag preferably makes up 0.2 to 3.0% by weight of the hotmelt adhesive.

Another embodiment is characterized in that the film has a thickness of 2 to 150 μm and, more particularly, in the range from 10 to 100 μm.

Production of the Separate Portions of the Hotmelt Adhesive

In another embodiment, the separate portions of the hotmelt adhesive are produced by extruding the molten adhesive and size-reducing the resulting strands into granules. This enables the process to be carried out rapidly and continuously. The temperature of the molten adhesive is preferably selected so that its viscosity during the extrusion process is at least 2,000 mPas. The preferred temperature of the pressure-sensitive hotmelt adhesive during the extrusion process depends on its composition. With standard pressure- sensitive hotmelts, it has been found to be of advantage for the temperature of the adhesive during extrusion to be in the range from about 80 to about

150°C and, more particularly, in the range from about 110 to about 130°C.

The low temperature of the separate portions until they have been bagged is crucial to the invention. This requirement is satisfied particularly economically if the molten adhesive is extruded into a cooling fluid, more particularly into a water bath, of which the temperature is sufficiently low for the separate portions to have substantially no surface tackiness. The temperature of the cooling fluid depends on the adhesive composition. For standard pressure-sensitive hotmelts, the temperature of the cooling fluid is preferably at most about 8°C and, more preferably, at most about 6°C.

In general, cooling is sufficient to prevent surface tackiness of the separate portions until they have been bagged. However, in order to support the cooling effect, the cooling fluid may contain a release agent, more particularly a fatty acid derivative and, in a particularly preferred embodiment, a stearate. Where a release agent is used, the temperature of the cooling fluid does not have to be as low as without the release agent and/or the time elapsing from cooling of the separate portions to bagging can be lengthened. However, the process according to the invention can also be carried out without a release agent, in which case weakening of adhesive strength or any other adverse effect on the product properties is avoided.

In the practical application of the bagged portions of pressure-sensitive hotmelt adhesive, a minimal amount of air in the bags is advantageous, as explained in the foregoing. Accordingly, another embodiment of the invention is characterized in that the separate portions are granules substantially spherical in shape and in that the granules have different diameters. Where the adhesive is extruded into a water bath, this requirement can be satisfied by using a multiple-bore extrusion die with different bore diameters. In this way, the bags can be filled with far fewer inclusions of air. In one particularly preferred embodiment, the granules have two different diameters, the diameter of the smaller granules being selected so that they fit into the empty spaces of a close packing formed from the large spherical granules and, to meet this requirement, the smaller granules have above all the largest possible diameter. Accordingly, this embodiment of the invention is directed towards filling the empty spaces formed during bagging of the large granules with the smaller granules which, in a particularly preferred variant, adjoin the surface of the larger granules on all sides.

The mixing of granules differing in size can be achieved in various ways. First, the extrusion die can have different bore diameters so that the granules differing in size can be simultaneously produced and mixed in the same granulator. Second, the granules differing in size can also be produced in granulators with different bore diameters and mixed in a subsequent step.

In addition, to obtain dense packing of the bags, it is of advantage for about 20 to about 40% by weight and more particularly about 30% by weight of the pressure-sensitive hotmelt adhesive to consist of the smaller diameter granules.

After the separate portions have been produced and cooled by a cooling fluid, more particularly water, the cooling fluid should be removed from the pressure-sensitive hotmelt adhesive. It has surprisingly been found that this can be done by drying in a drum dryer with warm air having a temperature of about 30 to about 40°C without the separate portions of pressure-sensitive hotmelt adhesive adhering to the walls of the dryer or to one another and forming lumps.

Packing of the Separate Portions in Bags (Bagging)

After their production, the separate portions of pressure-sensitive hotmelt adhesive are packed in bags. In another embodiment of the invention, the bags are welded and, to reduce the amount of air present, are evacuated above all before or during the welding step.

Bagging is preferably carried out in two ways. First, the dried granules can flow directly and continuously from the dryer into the bags. Second, the dried granules can first be collected, the low temperature necessary having to be maintained. The desired portions of granules can then be removed from the collecting container and bagged.

The bags are advantageously sealed by welding. If the hotmelt adhesive is stored at a temperature above its softening point, the adhesive is prevented from flowing out from the film by the weld seams. Storage temperatures as high as this occur repeatedly in practice, for example in hot summers on trucks or other uncooled storage facilities, especially in subtropical or tropical regions. In cases such as these, temperatures of up to 50°C and higher are reached so that the hotmelt adhesive softens. Accordingly, sealing of the film by bonding with the hotmelt adhesive is not sufficient in such cases because if pressure is applied to the bag, for example by other bags lying on top, the bond will open and adhesive will flow from the bag so that on the one hand it can no longer be used and, on the other hand, can cause considerable soiling which has to be cleaned up. The evacuation step advantageously avoids or at least considerably reduces the presence of air in the bags. However, it is not absolutely essential for carrying out the process according to the invention. The air present in the bags can also be forced out by squeezing the bags.

Another alternative method of avoiding or at least reducing the presence of air in the filled bags is to carry out the bagging process in the presence of a gas which condenses at room temperature or a gas which dissolves in the particular pressure-sensitive hotmelt adhesive, for example C0₂ or N₂0.

Further Treatment of the Filled Bags

It is of particular advantage if, in a final step, the evacuated and welded bag is exposed to pressure and/or elevated temperature so that homogeneous bag contents are obtained. By exposing the bag to pressure and/or elevated temperature, the inhomogeneous structure of the bag contents disappears so that a compact PSA hotmelt adhesive tightly surrounded by the bag film is obtained. Even if air could penetrate through the film over a period of time, it would be unable to enter the interior of the bag because the hotmelt adhesive is in close pressure-sensitive everywhere with the inside of the bag film. In addition, the bag can be given a shape particularly favorable for packaging, more particularly a square shape. This is because the bags are normally packed in relatively large boxes which are intended to be filled at tightly as possible with the bags.

The overall close pressure-sensitive of the hotmelt adhesive with the inside of the bag film, besides keeping air out of the bag, has another advantage during the melting process carried out by the user. The individual film zones of the bag do not melt separately, but always together with the adhesive adhering to the film so that the film material mixes with the adhesive during the actual melting process. By contrast, film zones of the bag which are not in close pressure-sensitive with the adhesive would melt separately so that individual droplets consisting of film material would be present in the melting pan in addition to the molten adhesive. These droplets of film material dissolve much more slowly in the adhesive than molten droplets which consist both of hotmelt adhesive and of film material.

The present invention also relates to a packaged pressure-sensitive hotmelt adhesive produced by the process described above.

Example

The Example was carried out with the extremely tacky pressure- sensitive hotmelt Euromelt 654 (a product of Henkel KGaA). It consists essentially of a rubber-based polymer, mineral oils and resins. The softening point, as measured by the ring and ball method and expressed as the R+B value, is 95°C; the viscosity is 2,000 mPas at 160°C, 4,900 mPas at 140°C and 17,000 mPas at 120°C.

The product was conventionally produced from the raw materials in a mixer at 160°C. To increase the viscosity, the product was introduced into the mixer and left therein to cool. Two days later, the product had reached a temperature of 115°C and was further processed at this temperature in a

Gala Industries machine suitable for the underwater granulation of non- surface-tacky hotmelt adhesives. To maintain the product temperature of 115°C, a secondary heating system with a temperature of 120°C was present. The product was pumped by a melt pump (speed 10-25 r.p.m.) through a Gneuβ filter (T = 115°C) and a startup gate (T = 115°C) directly to a heated multiple-bore extrusion die (T = 130°C).

The melt was forced through 50 bores of the extrusion die arranged in a circle. The bores had a diameter of 2.8 mm. The product throughput was varied between 90 and 380 kg/h. The blades rotating at 1600 r.p.m., which were positioned directly on the outlet side of the extrusion die, i.e. also underwater, chopped up the issuing strands of adhesive.

The stream of water was guided directly past the outlet side of the extrusion die. The water was kept at a temperature of 6°C by addition of ice. In this Example, 3% of the release agent SPL 117 (a product of Henkel KGaA based on calcium stearate) was added to the water. However, the process according to the invention can also be carried out with good results without the addition of release agents.

The spherical granules formed were transported by the stream of water to the preliminary drainage stage known per se. The water removed was recirculated. It can be kept at the desired temperature by means of a heat exchanger and/or a cooling unit.

The drained granules were then dried for about 15 mins. in a drum dryer using warm air (T = 30°C). By cooling the granules to about 6°C, surface tackiness could be prevented for about 20 mins. to such an extent that, surprisingly, even drying in the drying drum was possible without any problems.

Immediately after leaving the drying drum, the dried granules with a residual moisture content of less than 0.3% were packed in bags with a filling weight of 300 to 1 ,000 grams and preferably 600 grams. The bags consisted of 30 μm thick polyethylene film (low-density polyethylene, LD-PE). However, bags with a film thickness of 50 μm may also be used. They have the advantage of remaining substantially impermeable to air for a longer period. Immediately after evacuation, the bags were welded and packed in cardboard boxes. Accordingly, a film bag filled with the pressure-sensitive hotmelt adhesive is obtained as the end product.

Claims

1. A process for packaging a pressure-sensitive hotmelt adhesive in which separate portions of the hotmelt adhesive are produced and packed in a bag of plastic film which is suitable for melting together with the hotmelt adhesive and which has no surface tackiness at normal storage temperatures, characterized in that the separate portions are maintained at a temperature sufficiently low to substantially avoid surface tackiness until the portions have been bagged.

2. A process as claimed in claim 1 , characterized in that the plastic film is comprised of one or more polymers selected from the group consisting of polymers based on ethylene, polyamides, polybutadienes, polyesters, polycarbonates, atactic poly-α-olefins, thermoplastic polyacrylamides, polyacrylonitriles, acrylonitrile copolymers, polymethyl pentenes, polyphenylene sulfides, aromatic polyurethanes, styrene/acrylonitrile copolymers, acrylonitrile/butadiene/styrene copolymers, styrene/butadiene rubber, polyethylene terephthalates and mixtures thereof.

3. A process as claimed in claim 1 , characterized in that the plastic film is comprised of one or more polymers selected from the group consisting of polyethylene, ethylene/vinyl acetate copolymer and mixtures thereof.

4. A process as claimed in claim 1 , characterized in that the plastic film is comprised of LD polyethylene or ethylene/vinyl acetate copolymer containing up to 10% by weight of vinyl acetate in polymerized form and having a melting point below about 120°C.

5. A process as claimed in claim 1 , characterized in that the weight of the bag amounts to about 0.2 to about 3.0% by weight of the pressure-sensitive hotmelt adhesive.

6. A process as claimed in claim 1 , characterized in that the plastic film has a thickness of about 2 to about 150 μm.

7. A process as claimed in claim 1 , characterized in that, to produce the separate portions of hotmelt adhesive, the hotmelt adhesive is melted, the molten adhesive is extruded into one or more strands, and the strands are chopped into granules.

8. A process as claimed in claim 7, characterized in that the temperature of the molten adhesive during extrusion is selected so that the molten adhesive has a viscosity of at least about 2,000 mPas.

9. A process as claimed in claim 7, characterized in that the temperature of the molten adhesive during extrusion is about 80°C to about 150°C.

10. A process as claimed in claim 7, characterized in that the molten adhesive is extruded into a cooling fluid, which is maintained at a temperature sufficiently low for the granules to have substantially no surface tackiness.

11. A process as claimed in claim 10, characterized in that the temperature of the cooling fluid is at most about 8°C.

12. A process as claimed in claim 7, characterized in that the molten adhesive is extruded into a cooling fluid containing a release agent.

13. A process as claimed in claim 1 , characterized in that the separate portions are granules and are substantially spherical in shape and in that the granules have different diameters.

14. A process as claimed in claim 13, characterized in that the granules have two different diameters, the diameter of the smaller granules being selected so that the smaller granules fit into the empty spaces of a close packing formed from the larger granules and, to meet this requirement, the smaller granules have the largest possible diameter.

15. A process as claimed in claim 14, characterized in that about 20 to about 40% by weight of the granules consists of the smaller diameter granules.

16. A process as claimed in claim 13, characterized in that the granules are dried before bagging.

17. A process as claimed in claim 16, characterized in that the granules are dried in a drying drum at a temperature of about 30°C to about 40°C.

18. A process as claimed in claim 1 , characterized in that the bags filled with the separate portions are welded and are evacuated before or during the welding step.

19. A process as claimed in claim 18, characterized in that the evacuated and welded bag is exposed to pressure, elevated temperature, or a combination of elevated temperature and pressure so that homogeneous bag contents are obtained.

20. A packaged hotmelt adhesive produced by the process claimed in claim 1.

21. A process for packaging a pressure-sensitive hotmelt adhesive in which separate portions of the hotmelt adhesive are produced and packed in a bag of plastic film which is suitable for melting together with the hotmelt adhesive and which has no surface tackiness at normal storage temperatures, said process comprising the steps of

(a) extruding the hotmelt adhesive in melted form into one or more strands; and (b) chopping the strands into granules.

22. The process of claim 21 wherein the plastic film is comprised of low density polyethylene or ethylene/vinyl acetate copolymer containing up to 10% by weight of vinyl acetate in polymerized form and having a melting point below about 120°C.

23. The process of claim 21 wherein the weight of the bag amounts to about

0.2 to about 3.0% by weight of the pressure-sensitive hotmelt adhesive.

24. The process of claim 21 wherein the plastic film has a thickness of about 10 to about 100 μm.

25. The process of claim 21 wherein the molten adhesive is maintained at a temperature during extrusion such that the molten adhesive has a viscosity of at least about 2,000 mPas.

26. The process of claim 21 wherein the molten adhesive is maintained at a temperature during extrusion in the range of about 110°C to about 130°C.

27. The process of claim 21 wherein the molten adhesive is extruded into a water bath maintained at a temperature which is sufficiently low for the granules to have substantially no surface tackiness.

28. The process of claim 27 wherein the temperature of the water bath is at most about 6°C.

29. The process of claim 27 wherein the water bath contains a release agent.

30. The process of claim 29 wherein the release agent is a fatty acid derivative.

31. The process of claim 21 wherein the separate portions are granules, are substantially spherical in shape, and have two different diameters, the diameters of the smaller granules being selected so that the smaller granules fit into the empty spaces of a close packing formed from the larger granules and, to meet this requirement, the smaller granules have the largest possible diameter.

32. The process of claim 31 wherein from about 20% to about 40% by weight of the granules consists of the smaller diameter granules.

33. The process of claim 21 wherein the granules are dried before bagging in a drying drum at a temperature of about 30°C to about 40°C.

34. The process of claim 21 wherein the bags filled with the separate portions are welded and are evacuated before or during the welding step.

35. The process of claim 34 wherein the evacuated and welded bag is exposed to pressure, elevated temperature, or a combination of elevated temperature and pressure so that homogeneous bag contents are obtained.

36. The process of claim 21 wherein the pressure-sensitive hotmelt adhesive is comprised of a polymer selected from the group consisting of styrene- containing block copolymers, ethylene/vinyl acetate copolymers, ethylene/methacrylate copolymers, ethylene/n-butyl acrylate copolymers, polyolefins, polyvinyl acetates, polyacrylates, polyamides, polyesters, polyvinyl alcohols, polyurethanes and mixtures thereof.

37. A packaged hotmelt adhesive produced by the process of claim 21.

38. A process for packaging a pressure-sensitive hotmelt adhesive comprising the steps of

(a) extruding the hotmelt adhesive in melted form into strands in a cooling fluid; (b) chopping said strands into granules, the cooling fluid being maintained at a temperature which is sufficiently low to render the surface of the granules substantially non-tacky;

(c) separating the granules from the cooling fluid;

(d) packing the granules in a bag of plastic film which is suitable for melting together with the hotmelt adhesive and which has no surface tackiness at normal storage temperatures.

39. The process of claim 38 wherein the plastic film is comprised of one or more polymers selected from the group consisting of poyethylene, ethylene/vinyl acetate copolymers, and mixtures thereof.

40. The process of claim 38 wherein the weight of the bag amounts to about 0.2 to about 3.0% by weight of the pressure-sensitive hotmelt adhesive and the plastic film has a thickness in the range from about 10 to about 100 μm.

41. The process of claim 38 wherein the temperature of the molten adhesive during extrusion is selected so that the molten adhesive has a viscosity of at least about 2,000 mPas.

42. The process of claim 38 wherein the cooling fluid is comprised of water and, optionally, a release agent.

43. The process of claim 38 wherein the cooling fluid is maintained at a temperature of at most about 6°C.

44. The process of claim 38 wherein the granules are substantially spherical in shape and have two different diameters, the diameter of the smaller granules being selected so that the smaller granules fit into the empty spaces of a loose packing formed from the larger granules and, to meet this requirement, the smaller granules have the largest possible diameter.

45. The process of claim 38 wherein the granules are dried in a drying drum at a temperature of about 30°C to about 40°C before step (d).

46. The process of claim 38 wherein subsequent to step (d) the bag is welded and is evacuated before or during the welding step.

47. The process of claim 46 wherein the evacuated and welded bag is exposed to pressure, elevated temperature or a combination of elevated temperature and pressure so that the granules in said bag are homogenized.

48. A packaged hotmelt adhesive produced by the process of claim 38.