DE102007063021A1 - Self-adhesive tape consisting of adhesive mass layer on supporting layer, is subjected to corona treatment to improve adhesive shear strength - Google Patents

Abstract

In the production of a self-adhesive tape by applying adhesive mass layer(s) onto supporting material layer(s), the adhesive layer is subjected to corona treatment after application to the supporting layer. Independent claims are included for: (1) a self-adhesive tape obtained by the process; (2) a method for applying a self-adhesive tape, consisting of adhesive mass layer(s) on supporting material layer(s), onto a surface to be bonded, where at least one adhesive mass layer is subjected to corona treatment before application to the surface, the tape preferably being applied within a week of (especially immediately after) the corona treatment; (3) the use of corona treatment for (a) improving the shear strength of an adhesive mass, specifically the adhesive mass of a pressure-sensitive adhesive tape, or (b) improving the flow of a pressure-sensitive adhesive onto a substrate to be bonded; and (4) a dispenser for delivering a self-adhesive tape (5) (preferably a tape as described above), comprising a receiver (1) for a roll of the tape and (as the novel feature) at least one corona treatment device (3).

Description

The The present invention generally relates to the improvement of adhesive properties an adhesive and in particular a method for producing a self-adhesive tape, consisting of at least one carrier material layer and at least one layer of an adhesive, wherein first the adhesive layer is applied to the substrate layer a self-adhesive tape obtainable by this process, a method for applying such an adhesive tape to a To be glued surface and a dispenser for dispensing a such tape.

PSAs in particular UV-crosslinkable and UV-polymerizable PSAs - at These are mainly the polyacrylates to call - are have long been known and have a steadily growing importance the production of pressure-sensitive labels and adhesive tapes. They offer various advantages over the conventional, thermally crosslinkable systems. So can be UV-crosslinkable Acrylate polymers, for example, from the solution a carrier be applied flat, through Variation of the activator concentration and the UV dose in the desired Be networked way. The control of the crosslinking density and thus the product properties is thus in addition to the dosage also by the process parameters - here the UV dose - easily possible. Such dynamically controllable polymer systems are particularly advantageous in a modern production structure when a complex product portfolio based on a few basic building blocks to be realized.

in the The simplest case is a pressure sensitive adhesive base, for example a polyacrylate, a photoinitiator added, this sheet coated on a support material and by means of a UV radiation source irradiated. The result is a cross-linked pressure-sensitive adhesive layer that to an uncrosslinked mass by a substantial higher cohesion.

In the case of the UV activators added, a distinction is made between Type 1 and Type II activators: the former split off hydrogen atoms after UV activation, the latter abstracting them after UV activation. In particular, blended type I photoinitiators are generally incapable of producing crosslinkable radicals on a common saturated polyacrylate. Therefore, this strategy often does not result in efficient UV crosslinking of sheet-coated pressure-sensitive adhesives. This is more efficient in the published patent application DE 100 49 669 in which also an added a-splitter (eg oligo [2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] -propanone]) leads to a sufficient UV crosslinking of pressure sensitive polyacrylates leads.

Often it proves to be cheaper to incorporate the photoinitiator - for example by copolymerization or by polymer-analogous reaction - in the polymer. There are many examples of this. That's how it describes DE 24 43 414 A1 a process for the preparation of self-adhesive products with an adhesive based on crosslinked polyacrylic acid derivatives, wherein the adhesive comprises 0.01 to 5% of an acrylic acid or methacrylic acid [(2-alkoxy-2-phenyl-2-benzoyl) ethyl] ester as Contains photopolymerized polymerized and crosslinked by short-term irradiation with ultraviolet light. In the DE 27 43 979 A1 describes a process for the preparation of products which are coated with a self-adhesive composition based on crosslinked polyacrylic acid derivatives by copolymerization of a photoinitiator in the adhesive and subsequent crosslinking on the support material by short-term UV irradiation, wherein 0.01 to 5 as the photoinitiator Wt .-% benzoin acrylate or methacrylate are copolymerized in the self-adhesive. The EP 0 578 151 B1 describes the use of polyacrylate-based pressure-sensitive adhesives with polymerized benzoin derivatives for large-scale continuous melt-coating of medical products with subsequent crosslinking of the adhesive by UV irradiation. BASF AG describes polymerizable benzophenone derivatives which can abstract hydrogen atoms after UV irradiation ( EP 0 343 467 ; US 5,047,443 ; US 5,264,533 ). In contrast to the cleavable activators, these photoactivators do not form any low molecular weight constituents which can evaporate out of the hardened mass layer and adversely affect their properties. Thus, after UV irradiation, it forms, inter alia, in the patent DE 27 43 979 A1 systems described benzaldehyde, which can be perceived as a disturbing smell. Increasing the efficiency, it is also to incorporate unsaturated groups by polymer-analogous reaction in the polymer to be crosslinked. So will in US 5,391,406 and US 5,416,127 proposed to incorporate the polymer-bound vinyl groups targeted by a polymer-analogous reaction with dimethyl meta-isopropylenyl-benzyl-isocyanate (m-TMI). Such functionalized polymers can be coated from the melt without gelation since the temperature of the thermal polymerization of the isopropenyl group is below the coating temperature. When a photoinitiator is added to the polymer, the mass is UV-crosslinkable. Offenlegungsschrift DE 100 29 553 A1 describes the polymer-analogous reaction with (isocyanatoethyl) acrylic acid esters, and in the published patent application DE 100 29 554 A1 will benefit the use an extruder used to functionalize UV-crosslinkable polyacrylates.

In addition, there are so-called UV-polymerized coatings for many years. In this process, acrylate monomers are polymerized thermally or by UV irradiation until they have a sufficient coating viscosity. They are then coated while avoiding atmospheric oxygen on a substrate and then cross-linked by UV irradiation. This procedure is used in the US 4,181,752 and a variety of subsequent patents. A disadvantage compared to Hotmeltverfahren is the relatively high residual monomer content in the product.

When Special feature of UV-crosslinkable PSAs are still the over called a cationic mechanism crosslinkable masses. Here is an example of the Kraton Liquid concept. Furthermore also UV-crosslinkable synthetic rubbers are known.

All UV-crosslinkable pressure-sensitive adhesives share a more or less pronounced cross-linking profile (see also Donatas Satas, Handbook of Pressure Sensitive Adhesive Technology, 3rd. Edition 1999, page 532ff ). The ratio of incident light (I ₀ ) and translucent light (I) follows the dependence according to the Lambert-Beer law. As a consequence, the side facing the radiation source is more strongly networked than the side facing away from it. The cross-linking profile depends on the photoinitiator concentration, the layer thickness and the extinction coefficient. The cross-linking profile is enhanced when the side facing the radiation source is still particularly hot (IR radiation from the UV source) and the opposite side is particularly cold (non-reflecting cooling roller). The profile can counteract a reflection of the UV radiation or a double-sided UV irradiation. Both, however, is difficult to implement in practice.

For Some special requirements of adhesive tapes can be a strong one pronounced networking profile even be favorable, because this allows the Aufziehverhalten the mass on a substrate be reduced. However, a networking profile affects the setting of a balanced balance between adhesion and cohesion considerably. This is special in technical adhesive tapes, which is a high requirement put on the shear load at high weight load and over a wide temperature range stable adhesive technology Properties must have essential. Especially a high shear strength is a quality-determining Feature of such high performance adhesive tapes.

In the case of masses which are coated from the solution, this disadvantage of UV-crosslinked PSAs can be compensated in part by a particularly high molecular weight or the use of a high proportion of cohesion-increasing co-monomers, such as acrylic acid. However, this is not possible with acrylate hotmelt because a high molecular weight would render melt-coatability almost impossible, and cohesion-enhancing co-monomers also lead to a disproportionate increase in coating viscosity. Minor improvements result from the method according to DE 100 36 801 A1 (Tempo) and DE 100 30 217 (RAFT) using polyacrylates as hot melt pressure sensitive adhesives having a narrow molecular weight distribution (low polydispersity). Compared to more widely distributed polyacrylates of the same molecular weight, the more narrowly distributed masses are significantly more cohesive after crosslinking. This allows a reduction in the average molecular weight (Mw) of about 30% while maintaining the cohesion. Although these narrowly distributed polyacrylates promise high cohesiveness even at low molecular weight after crosslinking, quality degradation remains due to the crosslinking profile. In addition, the manufacturing process of these narrowly distributed masses is more complicated, since such regulators slow down the polymerization process.

An improvement of acrylate PSAs in the hotmelt process and the subsequent UV crosslinking is achieved by the preparation of closely distributed acrylate PSAs with copolymerized photoinitiators - as in US Pat DE 101 49 084 A set out - achieved.

task The present invention was therefore, adhesives, in particular PSAs with an improved adhesion behavior and improved shear strength to deliver. For UV-curable and UV-polymerizable PSAs should their benefits can be used, wherein at the same time overcome the disadvantages caused by the profile of crosslinking should be.

Surprisingly Corona treatment was found to be the adhesion properties of Adhesives significantly improved and a significant increase the shear strength leads.

Corona treatment is a chemical-thermal process for increasing the surface tension / surface energy of polymeric substrates. Between two electrodes are in a high voltage Discharge strongly accelerates electrons, which leads to an ionization of the air. When a plastic substrate is placed in the path of these accelerated electrodes, the accelerated electrodes thus produced strike the substrate surface at 2-3 times the energy needed to superficially disrupt the molecular bonds of most substrates. This leads to the formation of gaseous reaction products and highly reactive, free radicals. These free radicals can react rapidly in the presence of oxygen and the reaction products to form various chemical functional groups on the substrate surface. Functional groups resulting from these oxidation reactions contribute most to increasing the surface energy. The corona treatment can be done with two-electrode, but also with single-electrode systems.

The Corona treatment is commonly used to treat non-polar surfaces and foils used so that their Wettability increases. So are plastic films before printing or the application of adhesives subjected to a corona treatment. It is also known to apply an adhesive to a corona treatment subject if another adhesive is laminated on it should, in order to better adhesion of the further adhesive here to reach on the first adhesive.

Of the Specialist would therefore have expected that the corona treatment a pressure-sensitive adhesive for a degradation of the upper layers of this adhesive layer This would lead to the result that weight bearing this degraded polymers form a weak layer and lubricates the mass (Lubricating layer).

Surprisingly Instead, it was found that a corona treatment z. B. one UV or a chemically-thermally crosslinked layer to a significant Improvement of the shear strength (shear adhesion) leads.

Becomes A coated PSA corona-treated, so become surfaces Close bonds partially broken, and it form free Radical. These oxidize rapidly with the available atmospheric oxygen and resulting gaseous reaction products, resulting in a partial functionalization of the surface leads. In addition, the breaking up of the surfaces leads close Bonds to a reduction in molecular weight and thus to a better Auffließverhalten the PSA on the substrate surface. For strongly cross-linked, cohesive PSAs, this leads to a change in the Fracture in shear test from adhesion failure to cohesive failure. After flowing up the broken bonds recombine partly again, it comes to a "post-crosslinking" and thus a significantly increased shear strength. Amazingly, could be found that the corona treatment also the shear strength significantly increased by chemically-thermally crosslinked PSAs, z. B. in isocyanate crosslinking.

According to the invention an adhesive prepared in a known manner and in as well known manner coated on a carrier film. In the Adhesive is preferably a pressure-sensitive adhesive and particularly preferably a chemically-thermally crosslinked, an electron beam (ESH) crosslinked, an uncrosslinked cohesive or in particular a UV-crosslinked PSA, as the latter by the way good properties one for many applications inadequate Having shear strength.

When In addition, adhesives can, in essence all known adhesives are used.

So the adhesive of the adhesive tape can be based on an adhesive of solvent-borne natural rubber, synthetic rubber and acrylate adhesives. Preference is given to adhesives Basis of acrylate dispersions, particularly preferred are adhesives based on styrene-isoprene-styrene block copolymers, especially Adhesives based on hotmelt are preferred. These adhesive technologies are known and used in the tape industry.

The adhesive tapes can be produced by known processes. An overview of customary production methods can be found, for example, in Donatas Satas in Handbook of Pressure Sensitive Adhesive Technology, second edition, edited by Donatas Satas, Van Nostrand Reinhold New York pp. 767-808 , The known methods for drying and cutting the adhesive tapes can also be found in the Handbook of Pressure Sensitive Adhesive Technology, pages 809-874. Particularly noteworthy are hot melt or solvent based processes.

An adhesive which is particularly suitable on acrylate hotmelt basis which has a K value of at least 20, in particular greater than 30 (measured in each case in 1% strength by volume solution in toluene, 25.degree. C.), obtainable by concentrating a solution of such a composition into a system which can be processed as a hotmelt.

The Concentration can take place in appropriately equipped boilers or extruders, especially in the associated Degassing is a vented extruder preferred.

Such an adhesive is in the DE 43 13 008 C2 disclosed. The acrylate masses produced in this way is completely removed in an intermediate step, the solvent. The K value is determined in particular in analogy to DIN 53 726 ,

at The described method will additionally additional volatile Best shares removed. After coating, remove from the melt these masses only small amounts of volatile components on. Thus, all of the above-mentioned patent claimed monomers / formulations are taken over. One Another advantage of the compositions described in the patent is to see that these have a high K value and therefore a high molecular weight exhibit. The skilled person is aware that systems with higher Crosslink molecular weights more efficiently. This decreases accordingly the percentage of volatile components.

in the Case of the solvent-based pressure-sensitive adhesives, the Solution of the mass 5 to 80 wt .-%, in particular 30 to 70 Wt .-%, solvent included. Preferably are doing commercially available solvents used, in particular low-boiling hydrocarbons, ketones, alcohols and / or esters.

in the Processes are preferably single-screw, twin-screw or Multi-screw extruder with one or in particular two or more Deaeration units used.

In an adhesive based on Acrylathotmelt-based benzoin derivatives may be copolymerized, such as benzoin acrylate or benzoin methacrylate, acrylic acid or methacrylic acid ester. Such benzoin derivatives are in the EP 0 578 151 A described.

adhesives Acrylathotmelt-based can be UV-crosslinked. Other Types of networking are also possible, such as the electron beam crosslinking.

In a particularly preferred embodiment are as Self-adhesive co-polymers of (meth) acrylic acid and their esters having 1 to 25 carbon atoms, maleic, fumaric and / or Itaconic acid and / or esters thereof, substituted (meth) acrylamides, Maleic anhydride and other vinyl compounds, such as Vinyl esters, in particular vinyl acetate, vinyl alcohols and / or vinyl ethers used.

Of the Residual solvent content should be less than 1 wt .-%.

Farther It is possible to use an adhesive which is from the group of natural rubbers or the synthetic rubbers or from any blend Natural rubbers and / or synthetic rubbers consists, wherein the Natural rubber or natural rubbers basically made all available qualities such as Crepe, RSS, ADS, TSR, or CV types, as needed Level of purity and viscosity, and the synthetic rubber or the synthetic rubbers from the group of random copolymerized Styrene-butadiene rubbers (SBR), butadiene rubbers (BR), the synthetic polyisoprenes (IR), the butyl rubbers (IIR), halogenated butyl rubbers (XIIR), acrylate rubbers (ACM), of the ethylene-vinyl acetate copolymers (EVA) and of the polyurethanes and / or whose misery can be chosen.

Farther preferably, the rubbers can improve the Processability of thermoplastic elastomers by weight be added from 10 to 50 wt .-%, based on the Total elastomer fraction.

vicarious At this point, especially the most compatible ones should be mentioned Styrene-isoprene-styrene (SIS) and styrene-butadiene-styrene (SBS) types.

To improve the bond strength, tackifying resins may be added. Without exception, all previously known adhesive resins described in the literature can be used. Mention may be made representative of the rosins, their disproportionated, hydrogenated, polymerized, esterified derivatives and salts, the aliphatic and aromatic hydrocarbon resins, terpene resins and terpene phenolic resins. Belie Bige combinations of these and other resins can be used to adjust the properties of the resulting adhesive as desired. On the representation of the knowledge in the "Handbook of Pressure Sensitive Adhesive Technology" by Donatas Satas (by Nostrand, 1989) be explicitly noted.

Hydrocarbon resin is a collective name for thermoplastic, colorless to intense brown colored polymers with one molecular weight of generally <2000.

she can be divided into three large groups according to their provenance to divide: in petroleum, coal tar and terpene resins. The most important Coal tar resins are the coumarone-indene resins. The hydrocarbon resins are by polymerization of the unsaturated from the raw materials isolable Won connections.

The hydrocarbon resins are also calculated by polymerization of monomers such as styrene or by polycondensation (certain formaldehyde resins) accessible polymers having a correspondingly low molecular weight. Hydrocarbon resins are products with a softening range varying from <0 ° C (at 20 ° C liquid hydrocarbon resins) to> 200 ° C in a wide range and a density of about 0.9 to 1.2 g / cm ³ .

she are soluble in organic solvents like Ethers, esters, ketones and chlorinated hydrocarbons, insoluble in alcohols and water.

Under Rosin resin is understood to be a natural resin that is obtained from the crude resin of conifers. There are three Rosin types: Balsam resin as distillation residue of turpentine oil, root resin as an extract of coniferous rootstocks and tall resin, the distillation residue of tall oil. The In terms of quantity, the greatest importance has balsam resin.

rosin is a brittle, transparent product from red to brown Colour. It is insoluble in water, but soluble in many organic solvents like (chlorinated) aliphatic and aromatic hydrocarbons, esters, ethers and ketones as well as in vegetable and mineral oils. The softening point of rosin is in the range of about 70 up to 80 ° C.

rosin is a mixture of approx. 90% resin acids and 10% neutral substances (Fatty acid esters, terpene alcohols and hydrocarbons). The most important rosin resin acids are unsaturated Carboxylic acids of the formula C20H30O2, abietic, neoabietin, Lepopimar, Pimar, Isopimaric, and Palustric Acid, alongside hydrogenated and dehydrated abietic acid.

The Quantities of these acids vary in Dependence on the provenance of the rosin.

When Plasticizers can all be known from the tape technology plasticizing substances are used. These include including the paraffinic and naphthenic oils, (functionalized) oligomers such as oligobutadienes, isoprenes, liquid Nitrile rubbers, liquid terpene resins, vegetable and animal oils and fats, phthalates, functionalized acrylates.

To the The purposes of thermally induced chemical crosslinking are all previously known thermally activatable chemical crosslinkers such as accelerated Sulfur or sulfur donor systems, isocyanate systems, reactive Melamine, formaldehyde and (optionally halogenated) phenol-formaldehyde resins or reactive phenol resin or Diisocyanatvernetzungssysteme with the corresponding activators, epoxidized polyester and acrylate resins and their combinations can be used. The crosslinkers are preferably activated at temperatures above 50 ° C, in particular at temperatures of 100 ° C to 160 ° C, very special preferably at temperatures of 110 ° C to 140 ° C.

The Thermal excitation of the crosslinker may also be due to IR rays or other high-energy alternating electromagnetic fields take place.

In the next step, the adhesive is subjected to a corona treatment. The corona treatment is preferably carried out at a dose of 1 to 150 W · min / m ² . Particularly preferred is a dose of 25 to 100 W · min. / M ² and in particular a dose of 25 to 50 W · min. / M ^2. The electrode used is preferably a 5-rib profile electrode. The distance between the electrode and the adhesive is preferably 1,500 to 1,600 μm for a sample thickness> 100 μm. The web speed is - depending on the Device - at doses> 100 W · min. / M ² z. B. 30 to 50 m / min.

The process according to the invention can also be carried out under a protective gas atmosphere, z. B. under nitrogen, are performed.

According to the invention finds the corona treatment use in improving the shear strength of Adhesives, in particular pressure-sensitive adhesives, as well as in the improvement the flow of adhesives, in particular pressure-sensitive adhesives on the substrate to be bonded.

According to one Another aspect of the present invention is a self-adhesive tape provided after that described above Method is available. Such a self-adhesive tape has, in particular if it is an adhesive tape with UV or chemically-thermally crosslinkable Pressure-sensitive adhesive is one, compared to conventional Self-adhesive tapes significantly improved adhesion and shear strength.

at Such a self-adhesive tape may be the substrate layer both a permanent and a temporary carrier material layer be. In the case of a temporary substrate layer such "release" properties are especially preferred. Such adhesive tapes are used as a transfer tape, which enable a pressure-sensitive adhesive to be incorporated, d. H. without Carrier, to apply.

About that In addition, generally come as support materials in particular Crepe, paper, foils of polyester, PET, PE, PP, BOPP or PVC, Nonwovens, fabrics and fabric films and possibly release paper are used.

As generally known, the corona effect can not be permanently preserved, d. H. the effect decreases over time from. Therefore, the invention according to another Aspect of a dispenser for dispensing a self-adhesive tape available a susceptor for receiving a roll of the adhesive tape as well optionally a device for separating the adhesive tape from the dispenser, such as As a cutting device, and / or an Appliziervorrichtung such as B. comprises a pressure roller and / or a housing, and in the further at least one corona treatment device is integrated. This allows the pressure-sensitive adhesive tape to be applied immediately before application surface side are surface treated. To this end can a corresponding corona plant in a hand-held dispenser or with automatic application directly into the applying system such as B. an industrial robot can be integrated. For Hand dispensers are sufficiently small corona systems, for example with the spot generators HP-S and HP-D (HP-S: 650W / HP-D: 1300W double-spot) the Tantec as (Denmark) / tantec GmbH (Germany) on the market available.

at a corona dispenser, the electrodes of the corona systems are between to integrate the roll of pressure-sensitive adhesive film and the place of application. For both sides to be treated transfer tape must accordingly electrodes are integrated on both sides. Available in the market are both standard corona systems with electrode and counter electrode (usually an electrically conductive roller) and systems such as the spot generators of the company tantec, where the Discharge between two electrode straps within the Discharge head is generated and an electronic fan this discharge presses against the substrate surface, causing no Counter electrode required outside of the discharge head becomes.

Further the invention also provides a method of applying an adhesive tape, consisting of at least one carrier material layer and at least one adhesive layer, on a surface to be bonded available in which the at least one adhesive layer before applying to the surface of a corona treatment as described above.

advantageously, the application of the adhesive tape takes place within one week, preferably within one day, more preferably within one day Hour, and more preferably immediately after the corona treatment.

The The invention will be described in greater detail below with reference to examples described from which further advantages and design variants emerge.

example 1

When Example 1 is a PSA from BASF with the trade name ACResin 258 UV is used.

Example 2

As Example 2, a laboratory pressure-sensitive adhesive B is prepared as follows: A 2 L glass reactor conventional for radical polymerizations was reacted with 4 g (1% by weight) of acrylic acid, 4 g (1% by weight) of 2-hydroxyethyl methacrylate, 32 g (8 wt .-%) of methyl acrylate, 180 g (45 wt .-%) of butyl acrylate and 180 g (45 wt .-%) of 2-ethylhexyl acrylate and 266 g of solvent mixture [acetone / isopropanol (92.5: 7.5 )]. After gaseous nitrogen was passed through the reaction batch with stirring for 45 minutes, the reactor was heated to a temperature of 58 ° C and 0.2 g of 2,2'-azobis (2-methylbutyronitrile), [trade name Vazo 67 ^™ , DuPont ] added. Subsequently, the outer heating bath was heated to a temperature of 75 ° C and the reaction was carried out constantly at this temperature. After one hour reaction time, an additional 0.2 g of 2,2'-azobis (2-methylbutyronitrile) was added. After 4 and 8 hours each was diluted with a further 100 g of the solvent mixture. To reduce the residual initiators, 0.6 g of bis (4-tert-butylcyclohexanyl) -peroxy-dicarbonate [trade name: Perkadox 16 ^™ , Akzo Nobel] was added after 8 and 10 hours, respectively. The reaction was stopped after 24 hours and the reaction mixture was cooled to room temperature. From the polyacrylate, the laboratory adhesive was prepared with a terpene phenolic resin [trade name: Dertophene T 135 ^™ , DRT] [polyacrylate / terpene phenolic resin (70:30)]. Subsequently, the PSA was blended with 0.4% by weight hexamethylene-1,6-diisocyanate homopolymer [trade name: Desmodur XP2410, Bayer] (addition as 10% solution in acetone) (quantitative information based on the polyacrylate).

Example 3

When Example 3 is a finished natural rubber based product (NOPI 4349 of the Applicant).

Sample preparation

• (Dosen ermittelt mit UV Power Puck, Electronic Instrumentation and Technology Inc.)

The pressure-sensitive adhesives were coated on a 23 .mu.m support film by the method familiar to the person skilled in the art. The pressure-sensitive adhesive AcResin 258 UV was then crosslinked with an Eltosch UV laboratory dryer (medium-pressure mercury vapor radiator) with the following UV spectrum: UVA UVB UVC UVV 0.239 J / cm ² 0.199 J / cm ² 0.052 J / cm ² 0.169 J / cm ²

• (Cans detected with UV Power Puck, Electronic Instrumentation and Technology Inc.)

The Lab Haftklebasse B was crosslinked for 15 minutes at 120 ° C.

Corona treatment

Subsequently the samples were taken with a laboratory corona unit (VETAPHONE Corona Plus, generator: 2 kW CP-LAB, 5-rib profile electrode) on the ground side surface-treated. For this, the pattern is made by means of adhesive tape fixed on the counter electrode (roller), and the 5-rib profile electrode is over a defined distance of 1,600 or 1,500 um lowered the counter electrode with the pattern. The sample is with a rotation speed of 50 or 30 m / min. Corona-treated.

Adhesive testing

Directly after the corona treatment were standard Gel value, Shear life (RT, 40 ° C, 70 ° C), bond strength tested on steel and the micro-shear path.

Holding Power

A 13 mm wide strip of the respective sample pattern (adhesive tape) was applied to a steel plate. The steel plates were previously wiped four times with acetone and left for at least 1 minute, a maximum of 10 minutes in the air. The application area was 20 mm × 13 mm (length × width). The adhesive tape was then pressed four times onto the steel support by a 2 kg roller. A 1 kg weight was attached to the tape. The measured shear times are given in minutes and correspond to the average of three measurements. The measurement is carried out under normal conditions (23 ° C, 50% relative humidity; DIN 50014-23 / 50-1 ) and at 40 ° C and 70 ° C in a warming cabinet.

180 ° bond strength test

One 20 mm wide strip of the respective sample sample (adhesive tape) was applied to steel plates. The steel plates were previously Wiped four times with acetone and at least 1 minute, a maximum of 10 Minutes, left in the air. The pressure-sensitive adhesive strip was ten times with a 4 kg roll on the substrate. The tape was then immediately at 300 mm / min and subtracted from the substrate at 180 ° angle. The measurement results are given in N / cm and are averaged out of three measurements. All Measurements were carried out at room temperature. For calibration of the measurement procedure became a commercial test tape for testing non-adhesive coatings (type "tesa 7475" from tesa AG; on steel according to specification: 31.25 N / 25 mm) according to this Measurement method examined.

microshear

This Test is used to quickly test the shear strength of adhesive tapes under temperature load.

One from the respective sample pattern cut adhesive tape (length 50 mm, width 10 mm) is applied to a steel test plate cleaned with acetone glued so that the steel plate projects beyond the tape right and left and that the tape around the test plate at the top 2 mm surmounted. The bonding surface of the sample is height × width = 13 mm × 10 mm. The bond is then followed by a 2 Rolled over at a speed of 10 m / min six times. The tape will be flush with a sturdy tape reinforced, as a support for the position sensor serves. The sample is perpendicular by means of the test plate suspended.

The Sample samples to be measured are weighted at the bottom loaded by 100 g. The test temperature is 40 ° C, the test duration 30 minutes (15 minutes load and 15 minutes discharge).

The Shear distance after the given test duration at constant temperature is expressed as the result in μm, as the maximum value ["Max"; maximum shear distance through 15-minute loading]; as minimum value ["min"; Shear distance ("Restauslenkung") 15 min after Relief [with relieving a return movement takes place through Relaxation]. Also indicated is the elastic fraction in percent [ "Elast"; elastic proportion = (max - min) · 100 / max].

Gelwertbestimmung

Tyvek nonwoven bags [trade name: Tyvek L-1058 D ^™ , DuPont) are numbered with a toluene-solid pin and then weighed. 20 cm ^{2 of} the sample to be determined are punched out by means of an iron band and glued into the fleece bags. In addition, a blank test of the carrier is to be carried out. Then the edges of the non-woven bags are sealed with a foil sealer and the non-woven bags are re-weighed with the samples. In each case a maximum of 25 non-woven bags are transferred to a 1 L screw-cap glass, the glass filled to 75% with toluene and shaken for a total of 3 days, with daily change of toluene. At the end of the extraction, pour off the toluene, fill the glass with petrol (boiling point petrol 60 ° C-95 ° C) and shake again for 1 hour. The fleece bags are then removed, dried at 100 ° C-110 ° C in a convection oven and weighed again. In each case, the insoluble polymer residue (gel) of the sample is to be calculated. A possible loss of extraction of the carrier and other soluble or insoluble constituents of the sample should be taken into account and, if necessary, excluded. In each case, the arithmetic mean of three individual results is formed and specified in percent to a maximum of one decimal place.

Results

Table 1 shows the results of the adhesive testing. Example 1: AcResin 258 UV Example 2 Laboratory Adhesive - tesa without corona 50 Wmin / m ² without corona 50 Wmin / m ² Shear life (10 N, 13 × 20 mm) [minutes / fractional image], RT 443 (A) min 10000 min 5703 min 10000 min 40 ° C 239 (A) min 10000 min 803 min 10000 min 70 ° C 25 (M) min 2923 (K) min 47 min 10000 min adhesive power stole 4.4 N / cm 4.5 N / cm 8.0 N / cm 7.9 N / cm gel value 54 % 55.1 % 69.9 % 70.3 % microshear Max. 125 microns 122 microns 57 microns 55 microns 40 ° C, 2 x 15 min. elast. 94 % 90 % 85 % 82 %

Clear the increase in the shear strength after the corona treatment can be seen, otherwise virtually constant adhesive properties. The fracture pattern at the shear times changes accordingly from adhesion failure to cohesion failure. Consequently it is possible, strongly networked or very cohesive PSAs with a lack of adhesion or deficient Auffließverhalten by the corona treatment in high grade shear resistant systems.

Corona cans

• fM: flächig Massepunkte

The dependence of the shear strength on the corona dose was tested both on the pressure-sensitive adhesive AcResin 258 UV, as well as on the laboratory adhesive B and on the natural rubber all-purpose masking tape NOPI 4349. The results are shown in Tables 2 and 3. Laboratory adhesive - tesa AcResin 258 UV dose SSZ-RT B SSZ-40 ° C B SSZ-70 ° C B SSZ-RT B SSZ-40 ° C B SSZ-70 ° C B 0 Wmin./m ² 5703 A 803 A 47 A 443 A 239 A 25 A 25 Wmin./m ² > 10000 > 10000 > 10000 > 10000 > 10000 1460 K 50 Wmin./m ² > 10000 > 10000 > 10000 > 10000 > 10000 2923 K 75 Wmin./m ² > 10000 > 10000 > 10000 9685 K 384 K 2373 K 100 Wmin./m ² > 10000 > 10000 > 10000 6135 K 202 K 2188 K 125 Wmin./m ² > 10000 > 10000 > 10000 4442 K 244 K 1690 K 150 Wmin./m ² > 10000 > 10000 7168 K 6538 K 788 K 2025 K Table 2: Shear Times Examples 1 and 2 NOPI 4349 (natural rubber) dose SSZ-RT 0 Wmin./m ² 5063 sc 25 Wmin./m ² 6529 sc 50 Wmin./m ² > 10000 100 Wmin./m ² 8001 sc Table 3: Shear Times Example 3

• fM: areal mass points

The results show for the UV-crosslinkable pressure-sensitive adhesive AcResin 258 UV a strong improvement in the shear strength, which is relatively independent of the doses used. In the case of the chemically-thermally crosslinkable laboratory PSA B, particularly good values for shear strength are obtained at room temperature and 40 ° C. at doses of 25 or 50 Wmin./m ² , in the case of the natural rubber masking tape at a dose of 50 W min./ m ² .

In The attached figures are schematically different embodiments a corona dispenser shown.

there shows

1 a corona dispenser without counter electrode for a single-sided pressure-sensitive adhesive tape;

2 a corona dispenser without counter electrode for a double-sided pressure-sensitive adhesive tape;

3 a corona dispenser with counter electrode for a single-sided pressure-sensitive adhesive tape; and

4 a corona dispenser with counter electrode for a double-sided adhesive tape.

In the figures is a supply roll 1 shown on a pressure-sensitive film 5 is wound up. The pressure-sensitive adhesive film 5 runs over a pinch roller 2 with which it is applied to the substrate to be applied. In the case of a dispenser without counter electrode is, as in 1 and 2 shown between supply roll 1 and pinch roller 2 the electrode 3 arranged a corona system. In the case of in 1 the one-sided pressure-sensitive adhesive tape shown is the electrode 3 only on one side of the pressure-sensitive adhesive tape, on the one carrying the adhesive. In the case of double-sided pressure-sensitive adhesive tape, as in 2 shown on both sides of the tape in each case an electrode 3 arranged.

In the case of a corona system with electrode 3 and counter electrode 4 is in the case of in 3 shown one-sided pressure-sensitive adhesive tape between supply roll 1 and pinch roller 2 the electrode 3 again arranged on the side of the pressure-sensitive adhesive tape which carries the adhesive. On the other side is the counter electrode 4 , In 4 the arrangement for a double-sided pressure-sensitive adhesive tape is shown in which between supply roll 1 and pinch roller 2 two electrode / counter electrode pairs 3 . 4 are arranged, in such a way that on each side of the adhesive tape both an electrode 3 as well as a counter electrode 4 located.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 10049669 A [0004]
• - DE 2443414 A1 [0005]
• - DE 2743979 A1 [0005]
• - EP 0578151 B1 [0005]
• EP 0343467 [0005]
• - US 5047443 [0005]
• - US 5264533 [0005]
• - DE 2743979 A [0005]
• - US 5391406 [0005]
• US 5416127 [0005]
• - DE 10029553 A1 [0005]
• DE 10029554 A1 [0005]
• - US 4181752 [0006]
• - DE 10036801 A1 [0010]
• - DE 10030217 [0010]
• - DE 10149084 A [0011]
• - DE 4313008 C2 [0025]
• - EP 0578151 A [0029]

Cited non-patent literature

• - Donatas Satas, Handbook of Pressure Sensitive Adhesive Technology, 3rd. Edition 1999, page 532ff [0008]
• - Donatas Satas in Handbook of Pressure Sensitive Adhesive Technology, second edition, edited by Donatas Satas, Van Nostrand Reinhold New York pp. 767-808 [0022]
• - DIN 53 726 [0025]
• - "Handbook of Pressure Sensitive Adhesive Technology" by Donatas Satas (by Nostrand, 1989) [0036]
• - DIN 50014-23 / 50-1 [0066]

Claims (13)

A method for producing a self-adhesive tape, comprising at least one carrier material layer and at least one layer of an adhesive, wherein the adhesive layer is first applied to the carrier material layer, characterized in that after applying the adhesive layer to the carrier material layer, the former is subjected to a corona treatment. Method according to claim 1, characterized in that the adhesive is a PSA. Method according to claim 2, characterized in that that the adhesive is a UV-crosslinked PSA. Method according to claim 2, characterized in that the adhesive comprises a chemically-thermally crosslinked PSA is. Method according to claim 2, characterized in that that the adhesive is an electron beam (ESH) crosslinked PSA is. Method according to claim 2, characterized in that in that the adhesive composition comprises a urea crosslinked, pressure-sensitive adhesive is. Method according to one of the preceding claims, characterized in that the corona treatment with a dose between 1 and 150 W · min. / M ² , preferably 25 and 100 W · min. / M ² and in particular 25 and 50 W · min. / M ² takes place. Adhesive tape available after one of the Claims 1 to 7. Method for applying an adhesive tape, consisting from at least one carrier material layer and at least an adhesive layer, on a surface to be bonded, characterized in that the at least one adhesive layer before applying to the surface of a corona treatment is subjected. Method according to claim 10, characterized in that that applying within a week, preferably within one day, more preferably within an hour and especially preferably takes place immediately after the corona treatment. Using a corona treatment for improvement the shear strength of an adhesive, in particular an adhesive a pressure-sensitive adhesive tape. Using a corona treatment for improvement the flow of a pressure-sensitive adhesive onto the adherend Substrate. Dispenser for dispensing a self-adhesive tape ( 5 ), in particular according to claim 8, comprising a sensor ( 1 ) for receiving a roll of the adhesive tape ( 5 ), characterized in that the dispenser further comprises at least one corona treatment device ( 3 . 4 ).