EP0949013B1 - Process for manufacturing an adhesion promoting layer - Google Patents

Description

The invention relates to a method for producing at least one-sided Adhesive tapes, wherein between the carrier and adhesive for adhesion promotion Adhesive layers are applied to the carrier.

It is known that primer layers on sheet-like materials for a variety different applications are used. Examples are packaging materials, Adhesive tapes or protective films in which adhesion promoter layers in each case are provided in order to achieve sufficient strength of the composite layer. For adhesive tapes, this is often particularly problematic because generally high Requirements for the adhesion between adhesive and carrier material are made. A detachment of the adhesive from the carrier should neither during the removal of the adhesive tape of the role (before use) still when removing the tape of any Substrate (after use) take place.

To increase the adhesion of layers to web-like materials, in particular of adhesives on substrates with adhesive tapes, will be different Method used.

These are either methods for pretreating the sheet-like materials or for Coating with adhesion-promoting layers. As a pretreatment u. a. Corona treatment, flame pretreatment, fluorination or low pressure plasma treatment used. Adhesive layers, also called primers can, for example, as a wet chemical coating from solution (Solvent or water) are applied, with subsequent drying and / or networking is necessary.

All methods of increasing adhesion have specific disadvantages. The corona and The flame pretreatment are in many cases not effective enough to provide adequate Adhesion of subsequent coatings on the web-shaped materials too achieve. One example is the adhesion of acrylate-based adhesives to web-shaped adhesives Polyolefin-based materials. The same applies to the fluorination, which additionally with high safety effort is connected.

Another disadvantage of the flame pretreatment is the high thermal load of the treating materials, so that in particular temperature-sensitive materials can not or only partially be treated.

By the Niederdruckplasmavorbehandlung, with non-polymerizing gases (eg. As noble gases, oxygen or nitrogen) is carried out, it is generally possible to achieve better adhesion than with a flame or corona treatment. However, the high costs for the necessary vacuum equipment are problematic especially in the treatment of web-shaped materials. In many cases, the increase is the adhesion also lower than wet chemical primer, so that the use Plasma pretreatment is not useful for web-like materials.

The low-pressure plasma polymerization is not yet for the industrial production of Adhesive layers applied to web-like materials, although for dormant substrates already processes for a variety of different applications exist. Examples are the coating of plastic bottles with permeation barrier layers or the scratch-resistant coating of plastic surfaces. In web-shaped Materials is the use of low pressure plasma polymerization so far in general not useful, since the deposition rates are too low, so that coating time of Minutes or hours. For this is the production of coatings by low-pressure plasma polymerization in sheet-like materials, in particular the production of adhesive layers, uneconomical.

The use of primers, which are applied wet-chemically, usually brings high costs associated with the equipment of the sheet material with a primer a complete additional coating process means. There are also some Primer under environmental and health aspects classified as questionable, in particular because for wet chemical coating of the primer solvents are necessary.

The use of wet chemical primer is also problematic in rough web-shaped Materials, since it is difficult in these cases, a constant, even Layer thickness to achieve. In addition, temperature-sensitive materials can only conditionally coated with wet chemical primers, as an economical primer drying when processing web-shaped materials normally drying temperatures of at least 80 ° C is required.

Another problem exists when a particular layer, for example a Adhesive layer, on a particular sheet-like material with none of known methods can be sufficiently well adhered.

The object of the invention is to avoid the disadvantages of the prior art, at least diminish. In particular, it is the object of the invention in adhesive layers on carriers to achieve a significant liability increase, the Liability increase must be long-term stable, no solvents are used should and the procedure and the adhesive layers health and under Environmental aspects should be safe.

The object is achieved by a method for producing at least one-sided Adhesive tapes, wherein between the carrier and the adhesive for adhesion promotion adhesion promoter layers be applied to the carrier, as characterized in detail in the main claim is. The subject of the dependent claims are particularly advantageous embodiments of the procedure.

Accordingly, the invention relates to a method for producing at least one-sided Adhesive tapes, wherein between the carrier and the adhesive for adhesion promotion adhesion promoter layers be applied to the carrier by means of low-pressure plasma polymerization, by passing the carrier continuously through a plasma zone in which a low-pressure plasma is present, by electrical discharge, in particular kHz, MHz or GHz discharge is generated.

Important process parameters, the process of deposition of the adhesion-promoting Layers and thus control the layer properties are the monomers used or carrier or additional gases, the gas or gas mixture pressure during the coating and the electrical discharge used for plasma excitation. The variation of Process parameters serve to optimize and adapt the adhesive layers to the technical boundary conditions in the respective application. Especially can by way of appropriate choice of process parameters, as in the examples by way of example explains, a significant increase in the deposition rate compared to the state of Technique can be achieved so that coating times of less than 1 second result.

Preferably, it is coated at a gas pressure or mixed gas pressure of 10 ^-3 to 20 mbar.

Furthermore, it has proved to be advantageous if pulsed electrical discharges be used to generate the plasma.

In a further advantageous embodiment, the carrier is at a speed of more than 0.1 m / min, in particular greater than 50 m / min, through the coating zone emotional.

Further preferably, the coating times are shorter than one minute, in particular less than a second.

It is advantageous if the unwinding station of the carrier, the winding station and the Plasma zone in a vacuum chamber are located (batch operation) or the carrier means Vacuum locks is guided through the plasma zone, what as a so-called air-to-air operation referred to as.

To form the low-pressure plasma, in particular saturated hydrocarbons having chain lengths of C ₁ to C ₆ , in particular methane, ethane or propane, and / or mono- or polyunsaturated hydrocarbons having chain lengths of C ₁ to C ₆ , preferably acetylene or ethylene, and / or or oxygen or hetero element substituted compounds of the saturated or unsaturated hydrocarbons, such as ethylene oxide used.

As a carrier or additional gases are preferably non-polymerizable gases such Noble gases, oxygen, hydrogen, nitrogen or compounds respectively Gas mixtures used.

Additional and carrier gases are used to control the layer deposition and in particular, to increase the uniformity and the stability of the plasma.

The carriers are preferably Kunstoffolien, foam carrier, fabric carrier, non-woven carrier or paper carrier used.

The use of the adhesion promoter layers produced by means of the process according to the invention has proved to be particularly advantageous in at least one-sided adhesive tapes for bonding adhesion between the support and the adhesive.
A strong improvement in adhesion is particularly typical for the combination of acrylate-based vehicles and adhesives.

For plasma excitation, various forms of electrical discharge can be used become. This is preferably done by kHz, MHz or GHz discharge. critical for selection of the excitation form are the procedural constraints, for example, necessary coating speed or gas mixture pressure, during the coating.

A particular advantage of the method compared to the prior art is the possibility the process of layer deposition and thus the adhesion-promoting effect of To be able to control coatings by varying the process parameters. this makes possible an optimal adaptation of the coating properties to the respective application.

Another advantage of the novel process is the absence of solvents and the Possibility of using substances that are considered health or environmental aspects are to be avoided.

An additional advantage of the method is the ability to evenly with rough carriers Coating adhesive layers to coat.

In addition, the thermal load of the carrier due to the low pressure plasma used low, so that in particular temperature-sensitive materials such Polyethylene, polypropylene or foams can be coated without damage.

Another advantage is the high long-term stability of the novel adhesive layers, since these are highly cross-linked and thermally stable due to the novel process. In addition, these are insoluble in common solvents, so that their use, in particular for adhesion between carrier and wet-chemical applied Coatings, leads to very good results.

In the following, particularly advantageous embodiments of the invention Be presented method without wanting to restrict unnecessary.

Figur 1

den Aufbau einer erfindungsgemäßen Vakuumbeschichtungsanlage und

Figur 2

eine alternative Anordnung der Elektroden aus Figur 1.

It show the

FIG. 1

the structure of a vacuum coating system according to the invention and

FIG. 2

an alternative arrangement of the electrodes of Figure 1.

According to FIG. 1, the carrier 1 is moved from an unwinding station 2 through the plasma coating zone 3 moves. In the plasma coating zone 3, which is bounded by boundaries 8 from Remains of the vacuum chamber 7 is separated, monomers via a monomer 4 initiated. The plasma excitation and thus the fragmentation of the monomers takes place via a high-frequency alternating field which is applied between the electrodes 5 and 6. Electrode 5 is designed as a grounded cooling roller and thus serves the same time Transport of the carrier 1. Finally, the carrier 1 after coating a Winding station 9 fed.

An alternative arrangement of the electrodes 10, 11 is shown in FIG. 2. Both of these are Electrodes 10, 11 formed flat and the carrier 1 is non-contact by the Leaded electrode gap.

The selection of the respective electrode arrangement depends on the specific application from. In a plasma excitation by GHz discharge, the electrodes are by appropriate Replace GHz couplings.

Finally, the inventive method is exemplified, but without them also want to limit this unnecessarily.

example 1

On a polyester film (Hostaphan RN 25 film Hoechst AG, Frankfurt), transparent, 500 mm wide and with a thickness of 25 microns, a primer layer is applied by means of low-pressure plasma polymerization. The coating takes place in a plant according to FIG. 1 with an acetylene flow of 500 sccm and an oxygen flow of 50 sccm at a process pressure of 0.5 mbar. The film is passed at a speed of 100 m / min through the plasma zone (length 200 mm), so that a coating time of 0.12 sec results with a layer thickness of 130 nm. The plasma excitation takes place by means of kHz discharge. Subsequently, a transparent acrylate adhesive (self-polymer of 48% butyl acrylate, 48% ethylhexyl acrylate, 4% acrylic acid) is applied from solution to the adhesion-promoting layer (solvent acetone / gasoline, adhesive application after drying: 40 g / m ² ). The adhesion between adhesive and carrier film is checked by an anchoring test. For this purpose, an adhesive tape with the bonding agent layer according to the invention and a width of 20 mm is glued and rolled onto a PVC sheet (steel roll, 80 mm diameter, 2 kg weight, is pushed over the adhesive tape at about 10 m / min five times). and rolled over). Subsequently, the entire composite of adhesive tape with inventive adhesive layer and PVC plate for 3 days at 40 ° C and a humidity of less than 75% stored. The adhesion between Trägerfölie and adhesive is tested after storage by deduction of the test strip at a speed of 2400 mm / min at an angle of 180 ° or 90 °. Due to the adhesion-promoting layer according to the invention, the adhesion between the carrier film and the adhesive is increased substantially and surprisingly strongly and permanently, so that cohesive splitting of the adhesive occurs during the test. The adhesion between adhesive and carrier film is thus significantly better than comparative adhesive films in which instead of the primer layer according to the invention wet-chemical primer or a corona or flame pretreatment were used. In the case of the comparative adhesive tapes, an adhesive failure between the carrier film and the adhesive was observed in all cases, and thus a significantly poorer adhesion between the adhesive and the carrier foil.

Example 2

On a polypropylene film, transparent, 500 mm wide and with a thickness of 25 m, a primer layer is applied by means of low-pressure plasma polymerization. The coating takes place in a plant according to FIG. 1 with an acetylene flow of 500 sccm at a process pressure of 3 mbar. The film is passed at a speed of 50 m / min through the plasma zone (length 200 mm), so that there is a coating time of 0.24 sec with a layer thickness of 180 nm. The plasma excitation takes place by means of MHz discharge. Subsequently, a transparent acrylate adhesive (self-polymer of 47% butyl acrylate, 47% ethylhexyl acrylate, 6% acrylic acid) is applied from solution to the adhesion-promoting layer (solvent acetone / gasoline, adhesive application after drying: 40 g / m ² ). The adhesion between adhesive and carrier film is checked by an anchoring test. For this purpose, adhesive tape with the bonding agent layer according to the invention and a width of 20 mm are glued and rolled on PVC sheets (steel roll, 80 mm diameter, 2 kg weight, is rolled back and forth five times over the adhesive strip at about 10 m / min ). Subsequently, the entire composite of adhesive tape with inventive adhesive layer and PVC plate for 3 days at 40 ° C and an air humidity of 50% or 100% stored. The adhesion between backing film and adhesive is tested after storage by subtracting the test strips at a speed of 2400 mm / min at an angle of 180 ° or 90 °. Due to the adhesion-promoting layer according to the invention, the adhesion between the carrier film and the adhesive is increased substantially and surprisingly strongly and permanently, so that cohesive splitting of the adhesive occurs during the test. The adhesion between adhesive and carrier film is thus significantly better than comparative adhesive films in which instead of the primer layer according to the invention wet-chemical primer or a corona or flame pretreatment were used. In the case of the comparative adhesive tapes, an adhesive failure between the carrier foil and the adhesive was observed in all cases and thus a significantly poorer adhesion between the adhesive and the carrier foil.

Example 3

On a polypropylene film, transparent, 500 mm wide and with a thickness of 25 m, a primer layer is applied by means of low-pressure plasma polymerization. The coating takes place in a plant according to FIG. 1 with an ethylene flow of 1000 sccm at a process pressure of 0.5 mbar. The film is passed through the plasma zone (length 200 mm) at a speed of 20 m / min. The plasma excitation takes place by means of kHz discharge. Subsequently, a transparent acrylate adhesive (self-polymer of 47% butyl acrylate, 47% ethylhexyl acrylate, 6% acrylic acid) is applied from solution to the adhesion-promoting layer (solvent acetone / gasoline, adhesive application after drying: 20 g / m ² ). The adhesion between adhesive and carrier film is checked by an anchoring test. For this purpose, Kfir strip with the bonding agent layer according to the invention and a width of 20 mm are glued and rolled on PVC plates (steel roll, 80 mm diameter, 2 kg weight, is rolled back and forth five times over the adhesive strip at about 10 m / min ). Subsequently, the entire composite of adhesive tape with inventive adhesive layer and PVC plate for 3 days at 40 ° C and an air humidity of 50% or 100% stored. The adhesion between backing film and adhesive is tested after storage by subtracting the test strips at a speed of 2400 mm / min at an angle of 180 ° or 90 °. Due to the adhesion-promoting layer according to the invention, the adhesion between the carrier film and the adhesive is increased substantially and surprisingly strongly and permanently, so that cohesive splitting of the adhesive occurs during the test. The adhesion between adhesive and carrier film is thus significantly better than in comparison adhesive films in which wet-chemical primer or a corona or flame pretreatment were used instead of the adhesion promoter layer according to the invention. In the case of the comparative adhesive tapes, an adhesive failure between the carrier foil and the adhesive was observed in all cases and thus a significantly poorer adhesion between the adhesive and the carrier foil.

Example 4

On a polypropylene film, transparent, 500 mm wide and with a thickness of 35 microns, a primer layer is applied by means of low-pressure plasma polymerization. The coating takes place in a plant according to FIG. 1 with an acetylene flow of 500 sccm at a process pressure of 3 mbar. The film is passed through the plasma zone (length 200 mm) at a speed of 25 m / min to give a coating time of 0.48 sec with a layer thickness of 750 nm. The plasma excitation is carried out by pulsed MHz discharge at a pulse frequency of 10 ³ Hz and a duty cycle of 0.3. Subsequently, a transparent acrylate adhesive (Primal PS 83 D, Rohm and Haas GmbH, Frankfurt) is applied from solution to the adhesion-promoting layer (solvent water, adhesive application after drying: 20 g / m ² ). The adhesion between adhesive and carrier film is checked by an anchoring test. For this purpose, adhesive tape with the bonding agent layer according to the invention and a width of 20 mm are glued and rolled on PVC sheets (steel roll, 80 mm diameter, 2 kg weight, is rolled back and forth five times over the adhesive strip at about 10 m / min ). Subsequently, the entire composite of adhesive tape with inventive adhesive layer and PVC plate for 3 days at 40 ° C and an air humidity of 50% or 100% stored. The adhesion between backing film and adhesive is tested after storage by subtracting the test strips at a speed of 2400 mm / min at an angle of 180 ° or 90 °. Due to the adhesion-promoting layer according to the invention, the adhesion between the carrier film and the adhesive is increased substantially and surprisingly strongly and permanently, so that cohesive splitting of the adhesive occurs during the test. The adhesion between adhesive and carrier film is thus significantly better than comparative adhesive films in which instead of the primer layer according to the invention wet-chemical primer or a corona or flame pretreatment were used. In the case of the comparative adhesive tapes, an adhesive failure between the carrier foil and the adhesive was observed in all cases and thus a significantly poorer adhesion between the adhesive and the carrier foil.

Example 5

On a foam carrier (Alveolit TEE 1000.8, Alveo AG, Lucerne, Switzerland), 300 mm wide and with a thickness of 600 microns, a primer layer is applied by means of low-pressure plasma polymerization. The coating takes place in a plant according to FIG. 1 with an acetylene flow of 500 sccm and an argon flow of 50 sccm at a process pressure of 0.5 mbar. The film is passed at a speed of 20 m / min through the plasma zone (length 200 mm), so that a coating time of 0.6 sec results. The plasma excitation is done by means of kHz-discharge. Subsequently, a transparent acrylate adhesive (self-polymer of 47% butyl acrylate, 47% ethylhexyl acrylate, 6% acrylic acid) is applied from solution to the adhesion-promoting layer (solvent acetone / gasoline, adhesive application after drying: 50 g / m ² ). The adhesion between adhesive and carrier film is checked by an anchoring test. For this purpose, an adhesive strip with the adhesion promoter layer according to the invention (width 20 mm), as described in Example 1, is laminated to the foam carrier with the adhesion promoter layer according to the invention and the adhesive described. Subsequently, the entire composite is stored at 40 ° C and a humidity of 50% for 3 days in a drying oven. The adhesion between foam carrier and adhesive is tested after storage by deduction of the test strip. Due to the adhesion-promoting layer according to the invention, the adhesion between the carrier film and the adhesive is increased substantially and surprisingly strongly and permanently, so that cohesive splitting of the foam or detachment of the test strip occurs. The adhesion between adhesive and foam carrier is thus significantly better than in comparison samples in which a corona or flame pretreatment was used instead of the adhesion promoter layer according to the invention. In the case of the comparative samples, an adhesive failure between the foam carrier and the adhesive and thus a clearly poor adhesion was observed in all cases.

Example 6

On a polypropylene film, transparent, 500 mm wide and with a thickness of 35 microns, a primer layer is applied by means of low-pressure plasma polymerization. The coating takes place in a plant according to FIG. 1 with an acetylene flow of 500 sccm at a process pressure of 3 mbar. The film is passed through the plasma zone (length 200 mm) at a speed of 100 m / min. The plasma excitation is carried out by pulsed MHz discharge at a pulse frequency of 10 ³ Hz and a duty cycle of 0.3. Subsequently, a rubber adhesive (self-polymer of 43% natural rubber, 3% Sillithin Z 86 white, 12% zinc oxide, 21% Escorez® 1202 (exon), 20% Escorez® 365 (exon), 0.4% AS MBI 2 PLV® (Bayer), 0.6% Sontal® (Bayer)) from solution to the adhesion-promoting layer (adhesive application after drying: 20 g / m ² ). The adhesion between adhesive and carrier film is checked by an anchoring test. For this purpose, adhesive tape with the bonding agent layer according to the invention and a width of 20 mm are glued and rolled on PVC sheets (steel roll, 80 mm diameter, 2 kg weight, is rolled back and forth five times over the adhesive strip at about 10 m / min ). Subsequently, the entire composite of adhesive tape with inventive adhesive layer and PVC plate for 3 days at 40 C and a humidity of 50% stored. The adhesion between backing film and adhesive is tested after storage by subtracting the test strips at a speed of 2400 mm / min at an angle of 180 ° or 90 °. Due to the adhesion-promoting layer according to the invention, the adhesion between the carrier film and the adhesive is increased substantially and surprisingly strongly and permanently, so that the test strips can be completely removed again. The adhesion between adhesive and carrier film is thus significantly better than comparative adhesive films in which instead of the primer layer according to the invention wet-chemical primer or a corona or flame pretreatment were used. In the case of the comparative adhesive tapes, an adhesive failure between the carrier foil and the adhesive was observed in all cases and thus a significantly poorer adhesion between the adhesive and the carrier foil.

Claims (11)

1. Process for producing at least one-sided adhesive tapes, in which adhesion promoter layers are applied to the backing, between backing and adhesive composition, by means of low-pressure plasma polymerization for promoting adhesion, the backing being guided continuously through a plasma zone in which there is a low-pressure plasma which is generated by electrical discharge, especially kHz, MHz or GHz discharge.
2. Process according to Claim 1, characterized in that coating is carried out at a gas pressure or gas-mixture pressure of from 10^-3 to 20 mbar.
3. Process according to Claim 1 or 2, characterized in that pulsed electrical discharges are used to generate the plasma.
4. Process according to Claims 1 to 3, characterized in that the backing is conveyed through the coating zone at a rate of more than 0.1 m/min, in particular more than 50 m/min.
5. Process according to Claims 1 to 4, characterized in that the coating times are shorter than one minute, in particular lower than one second.
6. Process according to Claims 1 to 5, characterized in that the unwinding station of the backing, the winding station and the plasma zone are located in a vacuum chamber.
7. Process according to Claims 1 to 5, characterized in that the backing is guided through the plasma zone by means of vacuum locks.
8. Process according to Claims 1 to 7, characterized in that monomers used to form the low-pressure plasma are saturated hydrocarbons having chain lengths from C₁ to C₆, especially methane, ethane or propane, and/or mono- or polyunsaturated hydrocarbons having chain lengths from C₁ to C₆, preferably acetylene or ethylene, and/or oxygen- or heteroelement-substituted compounds of the saturated or unsaturated hydrocarbons.
9. Process according to Claims 1 to 8, characterized in that carrier gases or additional gases employed are non-polymerizable gases such as noble gases, oxygen, hydrogen, nitrogen or compounds, or gas mixtures.
10. Process according to Claims 1 to 9, characterized in that the adhesion promoter layers are virtually or completely transparent.
11. Process according to Claims 1 to 10, characterized in that backings that are employed are polymer films, foam substrates, woven substrates, non-woven substrates or paper substrates.

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