EP0173179A2 - Method for making surfaces slip-proof - Google Patents

Abstract

Process for the non-slip finishing of surfaces, in particular packaging materials, by applying a hot melt adhesive. This can be a fine-thread tangled nonwoven, the diameters of the threads being essentially between 300 and 10 µm, in particular 150 and 30 µm, and the adhesive mass being firmly fused together at the crossing points, or else being foam-like, with the foamed hot-melt adhesive being used by means of suitable application devices is applied to the surfaces in thin strands of 1 to 5 mm at intervals of 10 to 100 mm.

Description

The invention relates to a method for the non-slip finishing of surfaces, in particular packaging, both made of smooth plastics such as foils and other packaging materials based on paper and / or cardboard.

The non-slip finishing of a wide variety of surfaces has been causing problems for a long time, since contradicting properties are required in some cases from the suitable means. For example, a means for non-slip finishing of the most varied of surfaces should not lead to sticking or blocking of the rack pieces after prolonged exposure, because the surface, which can be printed, for example, is thereby affected when the individual parts are taken apart. On the other hand, however, it must be required that perfect adhesion is guaranteed even against the most varied movements such as shaking and bumping.

The interest initially focused on packaging materials made of cellulose materials such as paper and cardboard. Here, for example, aqueous dispersions of paraffins and / or polyalkylenes have been used, a certain content of paraffin or polyethylene, based on the mixture, which still determines Amounts of modified natural resins and / or natural resins and synthetic rubber contained were necessary. Such compositions, as are known from DE-PS 20 31 881, were primarily used as anti-slip agents in packaging made of paper or cardboard.

Aqueous coating agents have also proven successful with cellulose hydrate. It is known from DE-PS 15 19 433 to use aqueous polyvinylidene chloride dispersions with up to 3 percent by weight, based on the polymer of wax and / or paraffin. In addition, the presence of certain nonionic emulsifiers was essential.

These known agents were generally less suitable for carrying out transport securing for plastic films, for example made of polyethylene, polypropylene, polyesters, atactic copolymers of ethylene with butylene and polyamide films. In practice, a solution has become known in this regard in which a thin film has been pretreated in such a way that it has been given a rough surface by mechanical treatment or the application of plastic. These partially surface-treated foils are known commercially under the name "friction foil", but are expensive due to the very complex preparation and are therefore uneconomical for many packaging processes.

The object of the present invention was therefore to produce a non-slip surface layer on smooth surfaces made of plastics, in particular on packaging films and also on other sensitive surfaces, before or after packaging the material. This can be applied to the film before filling or, if necessary, applied to packaging items that have already been cooled to -40 ° C.

The process according to the invention for the non-slip finishing of surfaces, in which the disadvantages described above are avoided, consists in that a fine-thread or foamed application is carried out on the surface by means of hot melt adhesive, which after solidification without contact with other packaging material surfaces provides permanent non-slip equipment causes.

According to the invention, a fine-thread application of strands of these materials can be produced using the hot-melt adhesive mentioned, which has the shape of a fine-thread tangled nonwoven, the diameters of the threads being essentially between 300 and 10 μm, in particular 150 and 30 μm, and the melt adhesive mass at the crossing points are firmly fused together and the fleece was applied in 1 to 4, in particular 1 to 2, layers. Furthermore, the hotmelt adhesive can be applied with equal success in the form of foamed thin strands of 1 to 5 mm, in particular 1 to 3 mm in diameter at intervals of 10 to 100 mm, in particular 20 to 60 mm, from one another on the surface to be equipped.

Commercial hot melt adhesives are used as the basis for producing the tangled nonwoven from hot melt adhesives, which are sprayed above their melting point at temperatures between about 150 and 210, in particular 160 and 190 ° C. When spraying, the hot melt adhesive can be applied without any additional aids. In many cases, however, it is beneficial to use air or nitrogen heated to 60 to 120 ° C as a carrier.

It goes without saying that the external conditions are set in such a way that there is essentially no melting of the surface on which the hot-melt adhesive is applied in fine thread form. Only in the mic area, it may be appropriate that the surface to be coated softens somewhat and thus there is good anchoring between the threads of the hot melt adhesive and the film to be secured against slipping.

The filamentary hot melt adhesive can be applied directly by spraying onto the film to be used for packaging purposes. It is possible in particular; easily reproducible way to pre-treat packaging films and get an optimal order. Furthermore, it is possible to apply the anti-slip covering to objects already packaged only at certain points, either on one side of the packaging or on different sides, as well as in stripes, dots or in some other pattern.

The random fleece or the hot melt adhesive is applied by means of industrial applicators equipped with differently shaped application nozzles. The use of so-called swirl nozzles is a preferred embodiment because it enables an application that is relatively sharply delimited at the edges. Such nozzles were used in the examples below.

A variant of the method according to the invention for the non-slip finishing of surfaces using hot melt adhesives, in which the disadvantages described above are also avoided, consists in the fact that hot melt adhesives are foamed into thin strands of 1 to 5 mm, in particular 11 to 3 mm, by means of suitable application devices Diameter, at intervals of 10 to 100 mm, in particular 20 to 60 mm, from each other is applied to the surface to be equipped.

Commercial hot melt adhesives, as described above, are used as the basis for producing the foamed hot melt adhesive.

It has proven to be expedient to foam with a pressure of 2 to 8 bar from nozzles with a diameter between 0.15 to 0.6 mm at outlet temperatures between approximately 150 ° C. and 190 ° C. Known application devices are used for foaming, in which a gas which is largely inert to the hot adhesive is used as foam gas or carrier gas. This can be air, nitrogen-enriched air, nitrogen, carbon dioxide, argon or mixtures of these gases.

The hot melt adhesives themselves consist of conventional thermoplastic polymers which have a corresponding softening point or are adjusted to a practicable softening point with plasticizing resins.

The processing temperature of the hot melt adhesive is expediently between approximately 150 and 210 ° C., but in particular between 150 and 190 ° C. Polyolefins or copolymers of olefins, such as polyethylene, polypropylene themselves, and copolymers of ethylene with vinyl acetate, if appropriate with the use of vinyl propionate or of ethylene with methyl methacrylate or polymers of propylene with butene or copolymers of propylene, ethylene and butene, may be used Addition of dicyclopentadiene. Finally, from the series of ethylenic polymers, those are suitable which are formed from dicyclopentadiene and vinyl acetate, optionally with the addition of maleic acid monoethyl ester.

Another large group are the linear polyesters, which can also be structured in segments and are also available as commercial products. They can also be produced on the basis of adipic acid, optionally with the use of terephthalic acid and azelaic acid in the acid component, while the alcohol component consists of ethylene glycol, diethylene glycol, triethylene glycol or also low molecular weight polyethylene glycols with a molecular weight of 300 to 800.

Furthermore, good results have also been achieved with polyamides which have been prepared on the basis of dimerized fatty acids, if appropriate with the concomitant use of dicarboxylic acids such as sebacic acid or adipic acid and low-chain amines such as ethylene amine, propylene amine, optionally with the addition of polyether diamines with molecular weights between about 400 and 2,000.

Finally, the hot melt systems can also contain synthetic hydrocarbon resins or also polyterpene or polyinden resins. Since the melts often have to be heated to higher temperatures for a longer period of time, the addition of heat stabilizers is recommended. Phenolic such as substituted monophenols or organic disulfides such as e.g. Laurylstearylthiodipropionic acid ester.

; It may be useful to incorporate coloring substances to make the application of the hot melt adhesive more visible.

• Man trägt bei Wirrvliesen aus Düsen eines Durchmessers von 0,5 bis 2,5 mm 0 die Schmelzklebermasse bei Temperaturen von 150 bis 210 °C auf. Es wird ein Überdruck von 0,5 bis 8 bar angewendet.

i With regard to the procedures of the order, it has proven to be advantageous to observe the following conditions:

• In the case of tangled nonwovens, the melt adhesive mass at tempera is carried from nozzles with a diameter of 0.5 to 2.5 mm doors from 150 to 210 ° C. An overpressure of 0.5 to 8 bar is used.

In the case of the foamed hotmelt adhesive, a pressure of 2 to 8 bar is applied from nozzles with a diameter between 0.15 to 0.6 mm at outlet temperatures between about 150 and 190 ° C.

In the case of tangled nonwovens, hot-melt air or nitrogen from 60 to 120 ° C can be used to apply hot-melt adhesive mass from 150 to 190 ° C to packages that are already frozen to -40 ° C and have a plastic surface, on one or both sides of the contacting surfaces of the Apply stacking packages.

The foamed hot melt adhesive can be applied directly to the film to be used for packaging purposes. It is thus possible to pre-treat packaging films in a particularly reproducible manner and to obtain an optimal order. Furthermore, it is possible to apply the anti-slip covering not only in stripes, but also in punctiform or patterned fashion to items already packaged only at certain points, either on one side of the packaging or on non-contacting sides.

If the hot-melt adhesive is highly saturated with air or inert gas, the adhesive can also be applied to very thin thermoplastic films without them being melted. The problem of melting does not occur with thicker films.

The incorporated air or the carrier gas not only greatly reduces the influence of heat on the surface, but also the degree of saturation of the gas in the melt and the thickness of the coating Set liability variably. It is thus possible to go from a pure anti-slip coating to a weak bond which can be easily separated when depalletizing and which retains the anti-slip effect even after repeated palletizing.

The invention accordingly also relates to non-slip surfaces on plastic surfaces of packages, consisting of an arbitrarily arranged system of thin strands of foamed hotmelt adhesives, as can be produced from foam hotmelt adhesives according to the procedure described above.

By varying the saturation with different foam gas as well as the diameter and temperature of the strands, the compressibility of the applied foam can be adjusted in the desired manner and an optimal contact surface can be achieved in relation to the weight of the filling material.

Examples

• A) Ataktisches Copolymerisat aus Propylen und Butylen im molaren Verhältnis von etwa 1 : 1 mit untergeordneten Mengen (zwischen 0,1 und 0,05 Mol) an Ethylen, dessen Erweichungsbereich zwischen 74 und 80 °C lag. Die Viskosität bei 180 °C lag zwischen 7 000 und 9 000 mPa·s.
• B) Ein Hotmelt aus einer Mischung von 82,5 Gew.-% Ethylenvinylacetat-Copolymerisat (28 Mol-% Vinylacetat), 11,0 % eines handelsüblichen Kohlenwasserstoffharzes (Erweichungspunkt 85 °C), 6,0 Gew.-% Mikrowachs und 0,5 Gew.-% Butylhydroxytoluol. Die Viskosität bei 180 °C dieses Hotmelts betrug 19 000 mPa·s.
• C) Der Hotmelt bestand aus 60 Gew.-% ataktischem Polypropylen, 20 Gew.-% eines handelsüblichen Polyterpenharzes (Erweichungspunkt 105 °C), 19,1 Gew.-% handelsüblichen Tallharzes (Erweichungspunkt 75 °_C), 1,0 Gew.-% Butylhydroxytoluol.

The following adhesive mixtures A, B and _{C were used} to finish surfaces.

• A) Atactic copolymer of propylene and butylene in a molar ratio of about 1: 1 with minor amounts (between 0.1 and 0.05 mol) of ethylene, the softening range of which was between 74 and 80 ° C. The viscosity at 180 ° C was between 7,000 and 9,000 mPa · s.
• B) A hot melt composed of a mixture of 82.5% by weight of ethylene-vinyl acetate copolymer (28 mol% of vinyl acetate), 11.0% of a commercially available hydrocarbon resin (softening point 85 ° C.), 6.0% by weight of micro wax and 0 , 5% by weight of butylated hydroxytoluene. The viscosity at 180 ° C of this hot melt was 19,000 mPa · s.
• C) The hot melt consisted of 60% by weight of atactic polypropylene, 20% by weight of a commercially available polyterpene resin (softening point 105 ° C.), 19.1% by weight of commercially available tall resin (softening point 75 ° _C. ), 1.0% by weight. -% butylated hydroxytoluene.

Example 1

With a hot-melt gun for industrial purposes from Heinrich Bühnen KG, at 180 to 190 ° C outlet temperature using a 0.8 mm φ nozzle and a pressure of 4 bar and preheated air, threads were applied to a 60 µm thick film in a tangled position. The application thickness was about 1 to 2 layers on the film. A coating was obtained which looked like a microfine tangled nonwoven without enlargement.

At a microscopic magnification of 10 x 12.5, an image was obtained in which one could see significantly larger and smaller threads, which were fused together in the most diverse places, to a lesser extent lying loosely on one another. A characteristic section is shown in Figure 1.

5 boxes each, which were filled with 500 g deep-frozen spinach (-36 ° C), were packed and stacked on a pallet at a height of 12 on the base side.

This pallet was transported in a refrigerator truck for 250 km and then unstacked and stored in the cold room. There was practically no movement of the packages against each other during transport. Re-stacking was not a problem. The packaging could also be easily lifted apart.

Example 2

Gray boxes were sprayed ^p paratur for holding ice cream portion packs (2 ₀ pieces / carton) the dimension at a rate of 15 g / m ² of the hot melts according to B) in the manner as described above Auftragsa. The result was a fine-thread tangled nonwoven similar to Figure 1. After the packs had been filled with the portion packs, they were stacked by hand in the cold room. The backup was excellent.

Pallets with these packages were also transported in the refrigerated truck for 250 km and then reloaded into a cold store. Slipping of the packages was not observed during transport or during reloading into the cold room.

Example 3

The mixture according to C) was kept in the premelting vessel of an industrial application device for hot melt adhesive at 170 ° C. and applied through the application part via a 0.5 mm Ø nozzle with heated air by means of an overpressure of 0.8 bar to packages covered with shrink film. The packages consisted of 5 boxes of pizza and were frozen to -36 ° C. They were guided past the applicators so that a strip-like coating in the outer shape of a random fleece was achieved on the bottom surface and top surface (application about 0.5 g / pack, area about 800 cm ² ). The transport test was also carried out with this packaging in the refrigerated truck, which was passed without any problems.

Figure 2 shows a section of the 6-fold enlargement of the application of the melt adhesive web on the shrink film.

Example 4

On a cardboard with the dimensions 600 mm x 400 mm, two longitudinal strands each 2 mm wide and each with a length of 100 mm of the foamed hot melt adhesive according to B were transferred at the four corners parallel to the two longitudinal edges at a distance of 50 and 100 mm from the edge a nozzle with a diameter of 0.25 mm was applied, the adhesive application, based on the coated area, being approximately 12 g / _m ² . The adhesive was applied with air at a nozzle outlet temperature of 180 ° C., a pressure of 3 bar and a degree of saturation of 20%.

In this way, a permanently slip-resistant coating was achieved, which also withstood frequent repacking without diminishing the effect.

Example 5

Packets of 5 x 200 x 300 x 18 mm department store catalogs shrink-wrapped with PE film of 80 µm were applied with 25% nitrogen-saturated hot melt adhesive to C in two strips of 1 mm width over a length of 200 mm. The application temperature was 160 ° C, the pressure 2 bar, the adhesive consumption per package was 0.05 g.

A permanent anti-slip effect was achieved.

Claims (6)

1) A method of friction-finishing of surfaces, in particular Verpackunasstoffen with a smooth plastic surface by applying moving-inhibiting substances, characterized in that a fine denier or foamed job has been generated by strands of these materials on the surface by means of hot melt adhesive, which is either the shape of a feinfädi ^g en tangled nonwoven, the diameters of the threads are essentially between 300 and 10 microns, in particular 150 and 30 microns and the hot melt adhesive mass is firmly fused together at the crossing points and the application of the nonwoven in 1- to 4-, in particular 1- to 2 layered, or the shape of foamed hot melt adhesive in thin strands of 1 to 5 mm, in particular 1 to 3 mm in diameter, which were applied at intervals of 10 to 100 mm, in particular 20 to 60 mm, from one another on the surface to be equipped . 2) Method according to claim 1, characterized in that in the case of the tangled nonwoven from nozzles with a diameter of 0.5 to 2.5 mm Ø, the hot-melt adhesive is applied at temperatures of 150 to 210 ° C, an excess pressure of 0.5 to 8 bar is applied. 3) Process for the non-slip finishing of surfaces according to claim 1, characterized in that in the case of the foamed hot melt adhesive with a pressure of 2 to 8 bar from nozzles with a diameter between 0.15 to 0.6 mm at outlet temperatures between about 150 and 190 ° C applies. 4) Process according to claims 1 and 3, characterized in that by means of heated air or nitrogen from 60 to 120 ° C, a hot melt composition from 150 to 190 ° C * on already up to -40 ° C deep ^g efrorene packages comprising a plastic surface have, one or both sides on the contacting surfaces of the packages to be stacked. 5) Non-slip surface on plastic surfaces of packages, consisting of a fine-thread tangled nonwoven made of thread-like hot melt adhesive, the threads essentially having a diameter of 300 to 10 µm, in particular 150 to 30 µm, and at the points of intersection and contact with one another and also with the plastic surface are fused and the order of the mat 1 to 4, in particular 1 to 2 is ^la-g ig. 6) Non-slip surface on plastic surfaces of packages, consisting of an arbitrarily arranged system of thin strands of foamed hot-melt adhesive according to claims 1 and 3.

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