DE102004033516A1 - Self-adhesive medical product comprises an adhesive layer with a gel value profile such that the degree of crosslinking is highest on the support side and lowest on the application side - Google Patents

Abstract

Medical product with self-adhesive layer on one side of a support comprises an adhesive layer with a gel value profile such that the degree of crosslinking is highest on the support side and lowest on the application side. Independent claims are also included for: (1) analyzing the gel value profile of a medical product as above by dividing the product into surface-parallel sections with a cryomicrotome, extraction the sections and calculating the gel value as a function of depth from the weight loss during extraction; (2) controlling the crosslinking of adhesives in medical products as above, where a sensor-assisted measuring system for online determination of gel value varies the crosslinking of the adhesive via the effective radiation power when the gel value deviates from a predetermined target value; (3) producing medical products by applying an adhesive onto a support and irradiating the adhesive through the support.

Description

The Development concerns a medical product, being the medical one Product over the entire surface or partially self-adhesive and an adhesive layer having a gel profile and a method of preparation of the medical product by irradiation, with an adhesive layer vessel equipped Support material by means of electron beams and / or UV rays, the irradiation from the substrate side and a method of analysis of the trained gel profile in the medical product.

It is known to be olefinic unsaturated Monomers by UV radiation in the presence of sensitizers, such as benzoin, benzoin derivatives or azo compounds, to Polymeristion to be stimulated. With concomitant use of polyunsaturated Monomers can also while or crosslinking takes place after the polymerization.

The Radiation crosslinking takes place in the manufacture of medical, self-adhesive products are widely used, especially at the crosslinking of adhesives, which then carrier materials how plastic films, fabrics or nonwovens can be coated.

For example is in the case of acrylate PSAs for the production of outstanding adhesive properties a networking required. This also applies to rubbers achieved an improvement of the adhesive properties.

at the production of adhesive tapes indicates the application of radiation crosslinking by UV radiation or electron beam (ES) have particular advantages over the chemical / thermal crosslinking process.

mit D = Dosis in %, U_B = Beschleunigungsspannung in kV und X = durchstrahltes Flächengewicht in g/m2, bestehend aus Flächengewicht des Vakuumfensters, Luftspalt zwischen Vakuumfenster und Produkt und Tiefe im Produkt.The depth distribution of the absorbed dose of radiation in an accelerated electron irradiated product is known for any given acceleration voltage. Various authors have developed empirical functions for this purpose (for example Heger, beta-gamma 1, 20, 1990). Neuhaus-Steinmetz published the following empirical function at RadTech Europe, Mediterraneo 1993:

with D = dose in%, U _B = acceleration voltage in kV and X = radiated basis weight in g / m2, consisting of basis weight of the vacuum window, air gap between vacuum window and product and depth in the product.

Enough due to the high basis weight of a product the maximum acceleration voltage of the electron beam system for one enough uniform radiation not in the literature, the possibility of irradiation of described on both sides, with the same for both sides Acceleration voltage and radiation dose can be adjusted.

at UV crosslinking depends on the penetration depth of UV radiation the recipe and of the UV wavelengths at which to crosslink necessary photo initiator is stimulated.

at UV-crosslinkable adhesives, it is advantageous if the photoinitiator not released freely in the adhesive is, but chemically attached to the polymer chains of the adhesive is. This attachment typically occurs during polymerization, Otherwise, after the networking still existing photoinitiators cohesion decrease.

Furthermore, it is advantageous to use photoinitiators that do not react to sunlight and not to the light of incandescent or fluorescent lamps, because otherwise an uncontrolled post-crosslinking can occur. It follows that advantageously only photoinitiators are used, which at Wellenlän <300 nm are sensitive.

at However, the UV polymerization of adhesives does not come this or little to bear, as in the state of the art known UV polymerization as complete as possible the monomers to polymers is to be achieved. An after-reaction would in primarily to incorporate residual monomers, which is rather advantageous as harmful would. Accordingly One likes to use photoinitiators that intervene at UV wavelengths 300 and 400 nm are sensitive. Do you use these photoinitiators for the Polymerization of pure acrylate adhesives, this can be layer thicknesses significantly more than 1000 microns polymerize with good success.

For adhesive tapes with Shear-resistant UV-crosslinking adhesives are currently mainly photoinitiators used in the range of 250 to 260 nm their main sensitivity to have.

at The UV radiation generally decreases the intensity of the radiation in an exponential function with the depth off, if no side effects available. In pure acrylate adhesives, the UV intensity at a wavelength of 250 nm typically at a depth of about 25 to 35 nm only half the strength like on the surface. Accordingly, no later than from layer thicknesses of 60 to 90 μm severe impairment expect the adhesive properties, since then either the UV lamps facing away Page almost not cross-linked or facing the UV lamps Page heavily cross-linked becomes.

at many tapes With acrylate adhesives, the adhesive layers have strengths around 100 μm and also more. At these layer thicknesses For example, UV crosslinking is at wavelengths around 250 to 260 nm reasons described above already very problematic. Accordingly, such products typically thermally or electron beam crosslinked.

to Optimization of adhesive properties are often resins in the adhesives mixed. In the wave range of interest they absorb the UV radiation, however, quite strong, so that the production of a double-sided Adhesive tapes with adhesive layers of 50 microns is problematic and also in the resin selection in addition on one as possible low UV absorption must be respected.

The DE 198 46 901 A1 discloses a method for the radiation-crosslinking of adhesive tapes coated on one side, wherein the adhesive tape is irradiated by the carrier material of the adhesive tape to the adhesive so that the carrier material and the adhesive side facing the carrier material receive a dose of 30 to 200 kGy and the acceleration voltage during irradiation is chosen so that the dose on the open sticking side has dropped to 0 to 60 kGy.

hereby is achieved by that the high crosslinking of the adhesive layer on the wearer facing Page no migration of components to the open side of the carrier can take place while the adhesive properties of the tape on the networking in the area the open adhesive side over the electron beam dose decrease with the irradiated depth in Product to be discontinued.

The DE 198 46 902 A1 describes a process for the radiation-crosslinking of double-sided adhesive tapes, wherein a carrier material coated on both sides with adhesives in an irradiation device is irradiated asymmetrically from both sides with different doses.

• a) Beschichten eines Trägermaterials mit einem Kleber A,
• b) ES-Vernetzung des Teilproduktes Kleber A/Träger auf der Klebmasseseite mit einer an der ES-Anlage eingestellten Dosis A und Beschleunigungsspannung A,
• c) Eindecken des Klebers A mit einem Releaseliner,
• d) Beschichten der zweiten Seite des Trägermaterials mit dem Kleber B und
• e) ES-Bestrahlung des Verbundes auf die offene Seite der Klebmasse B mit einer an der ES-Anlage eingestellten Dosis B und Beschleunigungsspannung B, wobei die Seite mit dem Releaseliner vorzugsweise auf einer Kühlwalze durch die Elektronenbestrahlung geführt wird und wobei die Dosis A und die Dosis B und/oder die Beschleunigungsspannung A und die Beschleunigungsspannung B unterschiedliche Werte aufweisen.

In one of the preferred embodiments disclosed therein, the process for radiation-crosslinking of double-sided adhesive tapes consists of the process steps:

• a) coating a carrier material with an adhesive A,
• b) ES crosslinking of the partial product adhesive A / carrier on the adhesive side with a dose A set at the ES system and acceleration voltage A,
• c) covering the adhesive A with a release liner,
• d) coating the second side of the carrier material with the adhesive B and
• e) ES irradiation of the composite on the open side of the adhesive B with a set on the ES system dose B and accelerating voltage B, wherein the side with the release liner is preferably performed on a cooling roller by the electron beam irradiation and wherein the dose A and the Dose B and / or the acceleration voltage A and the acceleration voltage B have different values.

Typical irradiation devices used in the design of the method, represent linear cathode systems, scanner systems or multi-longitudinal cathode systems, if they are electron beam accelerators.

The Acceleration voltages range between 40 kV and 350 kV. The dose rates range between 5 and 150 kGy.

Prozeßananlysen have revealed that the epidermal and technological product properties, in particular through the depth dependence of the degree of crosslinking (gel value) are influenced. So far gave there is no way to set up a gel depth profile in the adhesive layer and analyze.

The known from the prior art self-adhesive medical support materials have a homogeneous adhesive layer, which is a compromise between the optimal degree of crosslinking on the carrier side and on the adhesive side represents. To get optimal adhesion on the skin is a lower cross-linking of the adhesive to the skin facing Page needed, so a good adhesion too is obtained in the skin pores. On the substrate side is a high Networking needs, so that the adhesive layer does not migrate into the substrate, i. is "absorbed" by the most open-porous carrier material or in this "infiltrated". The adhesive layer must have one have some minimum thickness to buffer between the regidem support material and to form the elastic skin. The adhesive layer also has to the task, the carrier material to shield from the skin.

So far the degree of crosslinking is only integrally by the so-called Gelwert characterized. Further information about the depth dependence the crosslinking reaction provide the previous chemical analysis methods Not.

Based on this known prior art, it is an object of the invention to provide advantageous and one-sided self-adhesive medical products, the adhesive layer having a gel profile, the highest degree of crosslinking at the transition from the carrier material to the adhesive layer (carrier side) prevails and the area with the lowest crosslinking in the area the application side (adhesive side) is formed, wherein the gel profile is constructed by selective radiation-chemical crosslinking with accelerated electrons or UV rays, by irradiation through the substrate. ( 1 ).

aim It is also the object of the invention to provide a self-adhesive medical To provide a product that is a prior art improved Rewinding behavior, d. H. a residue-free Removability from the skin and a higher anchoring force or a higher one adhesiveness on the skin due to more flexible consistency of the adhesive.

There the crosslinking reaction is the cohesion and adhesion properties the adhesive affects a targeted adaptation of the performance characteristics a medical tape (adhesion, rewinding, etc.) by knowing the local Distribution of the degree of crosslinking in the coated pressure-sensitive adhesive layer respectively.

1 shows the dependence of the cohesion and the adhesion of the gel value, wherein the corresponding decrease of the adhesiveness at the interface skin / adhesive with an increase of the cohesion (residue-free patch removal or reduction of the detachment of the adhesive from the carrier material) is associated with higher gel values or crosslinking energies. Conversely, too low degrees of crosslinking, due to the lower anchoring forces of the adhesive on the transition adhesive / carrier material promote the Klebmasseumspulung / transfer to the skin. Optimal medical products are therefore only available if a high cohesive force prevails at the adhesive / carrier material interface and high adhesion force at the skin / adhesive interface.

Be solved the problems described by a method as claimed 4 is laid down. The subclaims describe advantageous embodiments of the procedure.

• - die Klebmasse auf ein Trägermaterial aufgebracht wird,
• - das beschichtete Trägermaterial durch das Trägermaterial hindurch, bestrahlt wird.

Accordingly, the invention relates to a method for irradiating web-shaped coated with an adhesive carrier materials by means of electron beams and / or UV rays, wherein

• the adhesive is applied to a substrate,
• - The coated carrier material through the carrier material therethrough, is irradiated.

It is according to the invention also, that the coated substrate optionally guided by a second irradiation, in which the adhesive is irradiated on the second open, previously unexposed side.

• a) einer mit UV-Strahlung eines bestimmten Wellenlängenbereiches vernetzbaren Klebemasse und
• b) einem für diesen Wellenlängenbereich semitransparenten Trägermaterial kann ein in Bestrahlungsrichtung wirkender Vernetzungsgradient in der Klebemasse erzeugt werden (s. 1), der folgende vorteilhafte Eigenschaften aufweist: • Die der Haut zugewandte Seite der Kleberschicht wird durch die Absorption der UV-Strahlung in zunehmender Kleberschichttiefe immer geringer vernetzt, als beim Strahlungseintritt am Übergang Träger/Kleber. Damit ist die Klebemasse an der Kontaktstelle zur Haut weicher und kann sich den Unebenheiten und dem jeweiligen Rauhigkeitsprofil der menschlichen Haut besser anpassen. Die daraus folgende höhere Benetzung des betreffenden Hautareales ermöglicht ab einer bestimmten Schichtstärke einen intensiveren Kontakt des Schmelzhaftklebers mit der Haut und damit eine verbessertes Hauthaftvermögen (s. Ausführungsbeispiel). • Die dem Träger zugewandte Seite der Kleberschicht wird durch die höhere, nur teilweise durch den Träger absorbierte bzw. gestreute UV-Bestrahlungsdosis insbesonders am Übergang Träger/Kleber stärker vernetzt. Die damit einhergehende höhere Kohäsivität der Klebemasse bewirkt eine intensivere Verankerung der direkt oder im Transferverfahren beschichteten Klebemasse mit dem Trägermaterial. Bei der späteren Entfernung des klebenden Produktes von der Haut werden unerwünschte Kleberrückstände auf Haut oder Kleidung durch Klebmasseumspulung oder Aufreissen der Klebmasseschicht vermieden. • Zur Erzielung ausreichender Hautverklebungskräfte von Pflastern, Wundverbänden, Tapes usw. mit z.B. offenen Gewebe- oder Vliesträgern ist ein ausreichend dickes Klebmassepolster auf der jeweiligen Trägerstruktur erforderlich, um den zuvor genannten guten Kontakt des Schmelzhaftklebers mit der rauhen Hautoberfläche zu gewährleisten. Bei nicht ausreichend vernetzten Klebemassen sinkt die Klebmasse durch den sog. „kalten Fluss" allmählich in den Träger ein, sodass sich über die Zeit eine Klebkraftdepression einstellt. Diesen Effekt kann man in Grenzen durch ein erhöhtes Klebmasseauftragsgewicht versuchen zu kompensieren. Durch die vorliegende rückseitige UV-Bestrahlung wird insbesondere die für das Einsinken in den Träger verantwortliche Klebmassefraktion in Trägernähe relativ stärker vernetzt und damit am Träger „eingefroren", sodass die Klebmasse nicht mehr in den Träger einsinken kann und das Klebmassepolster auf dem Träger erhalten bleibt. (2) Hierdurch kann der sonst erhöhte Klebmasseauftrag abgesenkt werden. • Die im Stand der Technik üblicher Weise angewandte direkte UV-Bestrahlung der Kleberschicht erfordert insbesonders bei höheren Klebmasseaufträgen von z.B. >70g/m² eine genaue und aufwendige Prozesskontrolle der UV-Dosisenergie, um a) Übervernetzungen an der Klebmasseoberfläche und damit absinkende Klebkräfte zu vermeiden, aber b) gleichzeitig eine noch ausreichende Vernetzung an der Klebmasse/Träger-Grenze zu gewährleisten, um Klebmasseumspulungen bzw. Einsinken der Klebmasse in den Träger zu verhindern. In DE10163545 erfolgt die UV-Vernetzung durch eine doppelseitige Kombinationsbestrahlung und zwischengeschalteter Transferbeschichtung von einer Beschichtungswalze. Damit würden aber die zuvor angegebenen Vorteile der UV-Vernetzung via Rückseitenbestrahlung durch den Träger verloren gehen.

Due to the carrier-side irradiation of a laminar composite

• a) a crosslinkable with UV radiation of a certain wavelength range adhesive and
• b) a carrier material which is semitransparent for this wavelength range, a crosslinking gradient acting in the direction of irradiation in the adhesive can be produced (s. 1 ), which has the following advantageous properties: The skin-facing side of the adhesive layer is crosslinked by the absorption of UV radiation in increasing adhesive layer depth ever lower than when the radiation enters the carrier / adhesive transition. Thus, the adhesive is softer at the point of contact with the skin and can better adapt to the unevenness and the respective roughness profile of the human skin. The resulting higher wetting of the skin area in question allows a more intense contact of the hotmelt PSA with the skin and thus improved skin-care ability (see embodiment) above a certain layer thickness. The side of the adhesive layer facing the wearer is more strongly crosslinked by the higher UV irradiation dose, which is only partially absorbed or scattered by the wearer, in particular at the carrier / adhesive transition. The associated higher cohesiveness of the adhesive causes a more intensive anchoring of the directly or in the transfer process coated adhesive with the carrier material. In the subsequent removal of the adhesive product from the skin unwanted adhesive residue on skin or clothing by Klebmasseumspulung or tearing the adhesive layer are avoided. • In order to achieve sufficient skin adhesion of plasters, wound dressings, tapes, etc. with eg open fabric or non-woven backing, a sufficiently thick adhesive pad on the respective support structure is required to ensure the aforementioned good contact of the hot melt adhesive with the rough skin surface. In the case of adhesives that are not sufficiently cross-linked, the adhesive gradually sinks into the carrier due to the so-called "cold flow", so that an adhesive force depression occurs over time.This effect can be counteracted by an increased adhesive application weight In particular, the adhesive mass fraction responsible for sinking into the carrier in the vicinity of the carrier is relatively more crosslinked and thus "frozen" to the carrier so that the adhesive can no longer sink into the carrier and the adhesive pad is retained on the carrier. ( 2 ) As a result, the otherwise increased adhesive application can be lowered. The direct UV irradiation of the adhesive layer which is customary in the state of the art requires, especially at higher adhesive application rates of, for example,> 70 g / m ² an accurate and complex process control of the UV dose energy, in order to avoid a) cross-linking to the surface of the adhesive and thus decreasing adhesive forces , but b) at the same time to ensure a sufficient cross-linking at the adhesive / carrier boundary in order to prevent Klebmasseumspulungen or sinking of the adhesive into the carrier. In DE10163545 the UV crosslinking is carried out by a double-sided combination irradiation and intermediary transfer coating from a coating roller. This would, however, lose the previously stated advantages of UV crosslinking via backside irradiation by the carrier.

In a preferred embodiment is the adhesive with a nozzle, in particular slot die, Two- or multi-channel nozzle or adapter nozzle, web form formed.

Preferably For example, the adhesive may be sheet-shaped in a two-roll or multi-roll application system be and by means of another transfer roller on the the carrier material running, transfer the material to the substrate become.

Also, according to the invention, the medical product after it has been stained by the carrier material through, possibly a second UV or electron irradiation, the however, the other now open-sided side is subject to being subjected.

If the material is adhesive in some form, it is particularly advantageous to equip the transport device / anti-adhesive and / or transport of the material over the transport device / s by means of an anti-adhesive pad to be carried out.

In a further preferred embodiment of the method, a process release liner is used as the anti-adhesive backing, which does not necessarily have to remain in the product and which may be can be used several times. This is advantageously performed on a roll-up and coated with the adhesive. The adhesive is then transferred with a laminating roller to a support, which typically remains in the product.

These preferred embodiment the procedure is also for Electron beam crosslinking suitable. The resulting radiation doses in the adhesives can preferably up to 100 kGy and above, and ES acceleration voltages can chosen from 40 to 500 kV become.

In A particularly preferred variant of the method is the adhesive applied to a transport device in the form of a lay-up roller which is coated with a fluid or an antiadhesive coating, whereby the adhesion of the adhesive to the roll surface is prevented becomes.

The process module of the roll with an anti-adhesive coating is described in detail in US Pat DE 199 05 934 A1 as well as the process module of humidification by means of a fluid is described in detail in the DE 199 05 935 A1 disclosed. Both documents are hereby incorporated by reference, and the content of both documents forms part of this invention and thus becomes part of this disclosure.

When Adhesives can For example, acrylates, rubbers from solution, are used Dispersion, hotmelt adhesives, mixtures of acrylates and rubbers or mixtures of acrylates and tackifier resins, wherein the adhesives additionally still filled, colored and / or foamed could be.

When support materials for the mentioned tapes can for example, those made of PET, thermoplastic polymers, MOPP, BOPP, HDPE, LDPE, polyester, PVC, paper, nonwovens or foams.

Of importance in the medical field in particular, the water vapor permeability of the support materials, so is according to the invention, the use of permeable or semi-permeable carrier materials, such as Gore-Tex ^® membranes or open-pored PU foams.

Particularly advantageous are support materials of polyester-polyether copolymers, such as the Arnitelfolie ^® the company ACE.

When Substrate or carrier material can all known textile carriers such as woven, knitted fabric, scrim, Nonwovens or micro fleeces are used, wherein under "fleece" at least textile sheet according to EN 29092 (1988) and stitchbonded nonwovens and similar Systems are to be understood.

Also, lamination fabrics and knitted fabrics can be used. Such spacer fabrics are used in the EP 0 071 212 B1 disclosed. Spacer fabrics are mat-shaped laminates with a cover layer of a fibrous or filament nonwoven fabric, a backing layer and individual layers or tufts of retaining fibers present between these layers, which are needled through the particle layer distributed over the surface of the laminate body and interconnect the cover layer and the backing layer. As an additional but not required feature are according to EP 0 071 212 B1 particles of inert rock particles, such as sand, gravel or the like, are present in the holding fibers.

The Hold needled holding fibers through the particle layer the cover layer and the backing layer at a distance from each other and they are connected to the cover layer and the backing layer.

spacer fabric or -keepers are u. a. described in two articles, namely an article from the journal "Kettenwirk-praxis 3193", 1993, pages 59 to 63 "Raschelgewirkte Spacer "and an article from the journal "Kettenwirkpraxis 1/94", 1994, pages 73 to 76 "Raschelgewirkte Spacer "on the content of which is hereby incorporated by reference and the content thereof is part of this Revelation and invention will be.

knitwear are textile fabrics made of one or more threads or thread systems by Meshing (thread grinding), in contrast to woven goods (fabrics), at the area made by crossing two thread systems (warp and weft threads) is and the nonwovens (fiber composites), where a loser Fleece by heat, Needling, sewing or solidified by water jets.

knitwear can be knitted fabrics in which the threads in the transverse direction through the Textile run, and in knitted fabrics, in which the threads pass longitudinally through the textile run. Knitted fabrics are characterized by their mesh structure in principle, yielding, cuddly textiles, because the Mesh in length and width can stretch and endeavor to return to their starting position. They are very durable with high quality material.

When Nonwovens are particularly solid staple fiber webs, however also filament, meltblown and spun nonwovens in question, the most additionally to solidify. As possible Solidification methods are for Nonwovens mechanical, thermal and chemical hardening known. Become the mechanical fibers in most cases the fibers by turbulence of the individual fibers, by meshing of fiber bundles or by sewing of additional Threads in held together mechanically, can be characterized by thermal as also by chemical methods adhesive (with binder) or cohesive (binder-free) achieve fiber-to-fiber bonds. These can be with suitable formulation and process control exclusively or at least predominantly restrict to fiber nodes, so that under Maintaining the loose, open structure in the fleece nevertheless a stable, formed three-dimensional network.

Especially Advantageously, nonwovens have been found, in particular by oversewing with separate threads or solidified by meshing.

such solidified nonwovens are, for example, on stitchbonding machines of the "Malivlies" type from Karl Meyer, formerly Malimo, manufactured and are among others at the companies Naue Fasertechnik and Techtex GmbH available. A Malivlies is characterized in that a Cross-fiber fleece through the formation of stitches of fibers of the fleece is solidified.

When carrier can also be a fleece of the type Kunitvlies or Multiknitvlies be used. A Kunitvlies is characterized in that it out the processing of a longitudinally oriented Nonwoven fabric to a sheet This results in stitches on one side and meshes on the other or pile fiber pleats, but neither threads nor prefabricated sheets has. Such a nonwoven, for example, on stitchbonding machines of the type "Kunitvlies" of the company Karl Mayer for a long time Time made. Another characteristic feature of this fleece is that it as longitudinal fiber fleece in longitudinal direction high tensile forces can record. A Multiknitvlies is compared to the Kunitvlies thereby characterized in that Fleece by the two-sided piercing with needles both on the Hardened above as well as on the bottom.

Finally are also sewing fleeces suitable as a precursor to form an adhesive tape. A sewing fleece is out a nonwoven material formed with a plurality of mutually parallel seams. These seams caused by sewing or sewing of continuous textile threads. For this Type fleece are stitchbonding machines of the type "MaliwatC the company Karl Mayer, formerly Malimo, known.

Farther Particularly advantageous is a staple fiber fleece, which in the first step is pre-consolidated by mechanical processing or that is a wet web, hydrodynamically, with between 2% and 50% of the fibers of the nonwoven are melt fibers, in particular between 5% and 40% the fibers of the fleece.

One Such nonwoven fabric is characterized in that the fibers are wet or, for example, a staple fiber nonwoven through the formation of stitches of fibers of the fleece or by needling, sewing or Air and / or water jet machining is preconsolidated.

In a second step is the heat setting, the strength of the nonwoven by the melting or melting of the melt fibers again elevated becomes.

The Solidification of the fleece carrier let yourself also without binders, for example by hot embossing with structured rolls reach over with Pressure, temperature, residence time and the stamping geometry properties such as Strength, thickness, density, flexibility and. Ä. Can be controlled.

For the use of nonwovens, the adhesive bonding of mechanically pre-consolidated or wet-laid nonwovens is of particular interest, and this can be achieved by addition of binder in solid, liquid, foamed or pasty form. Basic forms of administration are variously possible, for example solid binders as powders for trickling, as a foil or as a grid or in the form of binding fibers. Liquid binders are dissolved in water or organic solvents or can be applied as a dispersion. about Binding dispersions are chosen for adhesive bonding: thermosets in the form of phenolic or melamine resin dispersions, elastomers as dispersions of natural or synthetic rubbers or usually dispersions of thermoplastics such as acrylates, vinyl acetates, polyurethanes, styrene-butadiene systems, PVC and the like. Ä., And their copolymers. Normally these are anionic or nonionogenically stabilized dispersions, but in special cases cationic dispersions may also be advantageous.

The Type of binder application can be made according to the prior art and is for example in standard works of the coating or the Nonwoven technology such as "nonwovens" (Georg Thieme Verlag, Stuttgart, 1982) or "textile technology nonwovens production" (employers circle Gesamttextil, Eschborn, 1996).

For mechanical Pre-consolidated nonwovens that already have sufficient bond strength have, offers the one-sided spray application of a binder on to surface properties to change specifically.

Next the economical use of the binder is in such operation The energy required for drying is also significantly reduced. There no Squeegee needed and the dispersions predominantly in the upper region of the Nonwoven remains, can unwanted hardening and stiffening of the nonwoven be largely prevented.

For a sufficient adhesive Solidification of the fleece carrier is generally binder in the order of 1% to 50%, in particular 3% to 20%, based on the weight of the fiber web, admit.

The Addition of the binder can already in the nonwoven production, at the mechanical pre-consolidation or in a separate process step carried out, which are carried out inline or offline can. After the binder addition, a condition temporarily needs to be established for the binder in which this becomes adhesive and adhesive Fibers connect - this can while drying, for example of dispersions, but also achieved by heating being, being over area or partial application of pressure further variations given are. The activation of the binder can be in known Drying tunnels, with suitable binder selection but also by means of infrared radiation, UV radiation, ultrasound, radio frequency radiation or the like respectively. For the later one End-use, it makes sense, but not mandatory, that the binder lost its stickiness after the end of the nonwoven manufacturing process Has. It is advantageous that by thermal treatment volatile Components such as fiber adjuvants are removed and thus a fleece with cheap Foggingwerte arises, so that at Use a low-fogging adhesive tape with special Great Fogging values can be produced.

A another special form of adhesive Consolidation is that the Activation of the binder by dissolving or swelling occurs. In principle, you can here also the fibers themselves or mixed special fibers the Take over the function of the binder. Therefore however, most polymeric fibers have such solvents from an environmental point of view are questionable or problematic in their handling, This method is rarely used.

When Starting materials for the textile carrier are in particular polyester, polypropylene, viscose or cotton fibers intended. The choice is not on the materials mentioned limited, but it can, for the Professional recognize without having to be inventive, a Variety of other fibers used for the production of the nonwoven become.

When support materials continue to find particular use laminates and nets, however also films (for example, a polyolefin from the group of polyethylenes (For example, HDPE, LDPE, MDPE, LLDPE, VLLDPE, copolymers of ethylene with polar comonomers)) and / or the group of polypropylenes (For example, polypropylene homopolymers, Polypropylene random copolymers or polypropylene block copolymers), mono- or biaxially oriented polypropylene, polyester, PVC, PET, Polystyrene, polyamide or polyimide), foams, foam, for example made of polyethylene and polyurethane, foamed films and creped and uncreped papers. Next you can these materials are pre- or post-treated. Common pretreatments are corona irradiation, impregnation, Coating, lacquering and hydrophobing; common aftertreatments are Calendering, tempering, laminating, punching and covering.

A low flammability of the carrier material and the entire adhesive tape can be achieved by adding flame retardants to the carrier and / or the adhesive. These may be bromoorganic compounds, if necessary with synergists such as antimony trioxide, but in view of the absence of halogen of the adhesive tape red phosphorus, organophosphorus, mineral or intumescent Ver compounds such as ammonium polyphosphate are used alone or in combination with synergists preferred.

When Adhesives can essentially all known adhesives are used which UV or ES partially transparent are.

When Adhesive is suitable for such on acrylate hot melt base, the has a K value of at least 20, in particular greater than 30 (measured each in 1 wt .-% solution in toluene, 25 ° C), available through Concentrate a solution Such an adhesive to a processable as a hot melt system.

Of the K value is determined in particular in analogy to DIN 53 726.

The Concentration can take place in suitably equipped boilers or extruders take place, especially in the concomitant degassing is a degassing extruder prefers.

Such an adhesive is in the DE 43 13 008 C2 explained. These acrylate masses produced in this way are completely removed from the solvent in an intermediate step.

In addition will be while more volatile Best shares removed. After coating, remove from the melt these adhesives only small amounts of volatile components. Thus everyone can in the above Patent claimed monomers / formulations are taken. Another advantage The adhesives described in the patent can be seen in that these have a high K value and thus a high molecular weight. The skilled person is aware that Systems with higher Crosslink molecular weights more efficiently. This decreases accordingly the proportion of volatile Ingredients.

The solution the adhesive may be from 5 to 80% by weight, in particular from 30 to 70% by weight solvent contain.

Preferably become commercial solvent used, in particular low-boiling hydrocarbons, ketones, Alcohols and / or esters.

Further preferably, single-screw, twin-screw or multi-screw extruders with one or in particular two or more degassing units are used. In the 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.

The Adhesive on Acrylathotmelt-based can be UV-crosslinked. Other Types of networking are also possible, for example electron beam crosslinking.

In a particularly preferred embodiment are used as self-adhesive copolymers of (meth) acrylic acid and their esters having 1 to 25 carbon atoms, maleic, fumaric and / or itaconic acid and / or their esters, substituted (meth) acrylamides, maleic anhydride and other vinyl compounds, such as vinyl esters, especially vinyl acetate, Vinyl alcohols and / or vinyl ethers used.

Of the Residual solvent content should be less than 1% by weight. Furthermore, an adhesive can be used which are from the group of natural rubbers or synthetic rubbers or from any blend of natural rubbers and / or synthetic rubbers consists, wherein the natural rubber or natural rubbers in principle all available qualities such as Crepe, RSS, ADS, TSR, or CV types, depending on the purity required. and viscosity level, and the synthetic rubber or the synthetic rubbers from the group the random copolymerized styrene-butadiene rubbers (SBR), the Butadiene rubbers (BR), the synthetic polyisoprenes (IR), the Butyl rubbers (IIR), the halogenated butyl rubbers (XIIR), the acrylate rubbers (ACM), the ethylene vinyl acetate copolymers (EVA) and the polyurethanes and / or their blends selected can be.

Farther preferably the rubbers to improve the processability thermoplastic Elastomers added at a weight fraction of 10 to 50 wt .-% be, based on the total elastomer content.

Representative may be mentioned at this point especially the most compatible styrene iso pren-styrene (SIS) and styrene-butadiene-styrene (SBS) types.

When Tackifying resins are invariably all known and in the Literature described adhesives used. Called to be representative the rosin resins whose disproportionated, hydrogenated, polymerized, esterified derivatives and salts, aliphatic and aromatic Hydrocarbon resins, terpene resins and terpene phenolic resins. any Combinations of these and other resins can be used to adjust the properties of the resulting adhesive as desired. On the presentation of the state of knowledge in the "Handbook of Pressure Sensitive Adhesive Technology "by Donatas Satas (von Nostrand, 1989) is explicitly pointed out.

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

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

To The hydrocarbon resins are also by polymerization of Monomers such as styrene or by polycondensations (certain formaldehyde resins) accessible Calculated polymers with correspondingly low molecular weight. Hydrocarbon resins are products with within wide limits of <0 ° C (at 20 ° C liquid Hydrocarbon resins) to> 200 ° C varying Softening range and a density of about 0.9 to 1.2 g / cm3.

she are soluble in organic solvents such as ethers, esters, ketones and chlorinated hydrocarbons, insoluble in alcohols and water.

Under Rosin resin becomes natural Resin understood that is obtained from the crude resin of conifers. There are three types of rosin: 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.

When Plasticizers can all softening substances known from adhesive tape technology be 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 phenolic resin or diisocyanate crosslinking systems 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 up to 160 ° C, most 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.

through the method according to the invention in particular in the further developed process variants is in for example a doubling of the sufficiently homogeneously irradiable layer thickness reachable. Especially with UV irradiation can thus also at smaller layer thicknesses of the exponential decrease of the total UV dose counteracted with the depth, whereby, for example, a Optimization between adhesion and cohesion better succeed.

Just when the method is used for the crosslinking of adhesive tapes, is in the case of UV crosslinking, a marked increase in the crosslinkable layer thicknesses or achieved a much more constant networking with the depth. In the case of electron beam crosslinking can be at a given maximum acceleration voltage doubling the networkable Layer thicknesses or the setting of desired depth dose profiles to reach.

Especially with structured surface supports such as fabrics, nonwovens and Pa It is advantageous to allow the absorbed radiation dose to rise from the open side to the wearer, but under certain circumstances also with smooth supports. As a result, a higher internal strength of the adhesive or a higher solvent resistance of the product is achieved while largely maintaining the surface properties of the adhesive sides.

Instead of A crosslinking can also be carried out in the described embodiments, a polymerization.

According to the invention, a all-over or partial coating with adhesives also by common coating methods such as printing (e.g., screen or offset printing), spraying, curtain Coating, spinfiber coating or double coating of the carrier material respectively.

Finally is the inventive method for the radiation-chemical crosslinking of coated support materials used advantageously, wherein a chemical reaction between the support material and the adhesive is initiated, creating covalent bonds between molecules the adhesive and molecules of the Adhesive are formed.

For the determination the degree of crosslinking makes use of the fact that high polymers Substances generally form gels in suitable solvents. gels are colloidal solutions, with the restriction, that the molecules not independent of each other and thus are not free to move. In contrast, uncrosslinked form Polymers either brine or real solutions, in any case theirs general solubility significantly better than the crosslinked polymer chains. By skillful Choice of solvent and In the experimental setup one can separate the gel from the sol in the solution and thus determine the gel content, which in turn then the degree of crosslinking characterized.

Method of analysis of the gel value

The Gelwertbestimmung is based on the principle of extraction, in which a substance mixture substance with the aid of a suitable solvent quititatively removed becomes.

m_Pv

= Probengewicht vor Extraktion

m_Pn

= Probengewicht nach Extraktion

m_T

= Trägergewicht der Probe

The gel value GW as an expression of the degree of crosslinking is calculated by the following relationship: GW = (m pv - m T ) / (M pn - m T ) * 100% With

m _pv

= Sample weight before extraction

m _Pn

= Sample weight after extraction

m _T

= Carrier weight of the sample

Inventive solvents have a boiling point below 150 ° C at normal pressure and a molecular weight between 40 and 200 grams per mole.

at the choice of solvent it is important that yourself this does not chemically react with the substance to be extracted, but only single substances dissolves.

Especially Advantageously, the extraction is carried out in a Soxhlet apparatus, wherein the extraction material by means of an extraction sleeve of filter paper in the Apparatus is introduced.

Of the Extraction loss of the pure carrier material is determined by blanks.

Method of analysis of the gel profile

in the context of the invention is also the method for the quantitative determination of the gel profile of adhesive layers of the inventive products.

The detection of the crosslinking process with a spatial resolution of 2 to 100 microns is carried out according to the following analysis method:
The direct experimental determination of the depth dependence of the degree of crosslinking succeeds according to the invention by the use of a cooled below the glass transition point of the adhesive Kryomikrotoms with the UV-irradiated adhesive layer surface-parallel with cuts of 2 to 100 microns thickness is mechanically divided. The gel values of the individual sections were then determined in the extraction method.

m

= Masse des Mikrotomschnittes

A

= Fläche der ausgestanzten Mikrotomprobe

ρ

= Dichte der Klebemasse

The model system used to determine the crosslinking gradient consists of a UV-transparent PP film which is coated with the polyacrylate mass to be crosslinked in a sufficiently high amount in order to completely absorb the crosslinking UVC radiation within the adhesive without disturbing reflections. The layer thickness h of the individual microtome sections is calculated from: h = m / (A · ρ) With

m

= Mass of microtome section

A

= Area of the punched microtome sample

ρ

= Density of the adhesive

The Number and layer thickness of the sections to be extracted for calculation the gel profile is based on the penetration depth of the UV radiation, to measure another measurable cross-linking effect. For meaningful results 15-20 cuts should be extracted.

Process Control / Onlinegrozesskontrolle of the gel profile

effective activities to ensure constant production conditions of UV-crosslinked adhesives, should be on a fast and continuous gel analysis based to the quality influencing deviations of the process parameters at an early stage recognize and correct.

The method according to the invention for the gel value detection in time intervals <100 ms is based on the absorption measurement of photoinitiator cleavage products which form during UV / ES irradiation. The concentration of these reaction products is proportional to the number of crosslinking centers in the adhesive and thus represents a measure of the gel value G. The transmission T in the wavelength interval 305-318 (λ ₁ ) nm can thus be determined by the spectral extinction coefficient K (depending on the respective gel value). G) of the reaction products with known layer thickness d by the following relation: T = exp (-K (G) .d)

Disturbing influences of the carrier material are eliminated by scaling the measurement signal to the adjacent transmission range at 335-350 nm (λ ₂ ), which is untouched by the crosslinking reaction. The gel value determination is thus reduced to a comparatively simple relative measurement. G = const · {InT (λ 1 ) - InT (λ 2 )} / D

Following the principle of a 2-channel photometer, the radiation of a low-intensity UV lamp is directed via a glass fiber optic onto the surface of the semitransparent carrier web coated with an already crosslinked adhesive. On the back of the carrier, a second fiber optic absorbs the UV radiation scattered by the adhesive and the carrier. The carrier web moves with the typical for coating processes web speeds between the permanently installed fiber optics. The transmitted UV radiation is separated by a beam splitter and 2 optical filters in the wavelength intervals (λ ₁ ) and (λ ₂ ) and measured their individual intensities with suitable detector elements (eg photodiodes). The time profile of the signal ratio of (λ ₁ ) and (λ ₂ ) is continuously calculated in an analog electronic divider, amplified and can be further processed via an analog / digital converter in a measuring PC. The time sequence of the measurement signal represents a measure of the current gel value of the UV-crosslinked adhesive via the above-mentioned formula relationship.

Assignment of the transmission values to gel profile over Comparative measurements (calibration curves)

Example for determination of the Gelwertgrofils:

A 70μ polypropylene film (measured transmittance 87% in the wavelength interval of 250-260nm) as a carrier material and a 150g / m ² coated acrylate adhesive with polymerized photoinitiator Benzoinacrylat (focal wavelength of crosslinking at 249.7nm), covered with siliconized release paper for ease of handling, was by unilateral irradiation by the PP carrier with already corrected by the carrier transmission UVC energies of 50mJ / cm ² , 25 mJ / cm ² and 10 mJ / cm ² in the wavelength interval of 250 to 260 nm with a microwave-excited UVC mercury radiator F450 (120W / cm) irradiated by Fusion system. The measurement of the carrier transmission and the irradiation dose was determined using a UVIMAP UVC meter from EIT.

The direct experimental determination of the depth dependence of the degree of crosslinking succeeds according to the invention the use of one at -30 cooled to C grade Cryomicrotome from Jung, with which the UV-irradiated adhesive layer surface parallel with sections of 5 μm Thickness was mechanically divided. The gel values of the individual sections were then determined by the Soxleth method and graphically evaluated.

3 shows the graphical representation of the gel profile as a function of the irradiation power.

From the typical forms of the gel value depth profiles ( 3 ) shows that both the height of the gel value and the maximum penetration depth of the crosslinking reaction is determined almost exclusively by the irradiated UVC energy. The significant decrease in the degree of crosslinking thus makes it possible to conclude on a property profile of the adhesive layers which varies continuously with the layer thickness.

Based The figures described below will be particularly advantageous versions closer to the invention explains without being unnecessarily limited by the choice of the figures shown want.

Comparison between adhesive mass side and carrier side radiotherapy

A sheet-like acetate fabric carrier of the company. Conze + Colsmann with a grammage of 95g / m ² and a web width of 1020mm was dried with the 249.7nm UV-curable solvent-based adhesive cello 33.33 with a Feststoffauftragsgewicht 70-75g / m ² in a tangential dryer , Directly at the dryer outlet, the coated support was UV-crosslinked in a 1450 mm wide U.V. irradiation channel of Fa.IST with 4 high-pressure mercury lamps with an electrical energy input of 120 W / cm at different web speeds and irradiation directions (carrier or adhesive side):
Sample A: Adhesion-side irradiation, v = 30 m / s
Sample B: Adhesion-side irradiation, v = 40 m / s
Sample C: Adhesion-side irradiation, v = 50 m / s
Sample D: carrier-side irradiation, v = 12 m / s

The irradiation energy measured at 15 m / min web speed with the UVIMAP was 190 mJ / cm ² . The measured transmission of the carrier was about 13%.

Of the Degree of crosslinking of samples A-D was by extraction of the uncrosslinked Polymer components of the adhesive matrix by means of a suitable solvent determined in a nonwoven using a Soxhlet apparatus.

The determined gel values of the samples AD were all in the range of 68-77%, the samples irradiated on the adhesive side as expected showing a slight increase with decreasing process speed, ie increasing UV dose with fixed irradiation power:

The so-crosslinked test patterns were applied in strips on the backs of 30 subjects below the scapula permutatively swapped for 24 hours. Thereafter, the patterns were examined for adhesion and rewrap of the adhesive scale during and after removal. The assessment of the adhesion was carried out according to the following rating key:
100 = ideal bonding, good adhesion
98 = approx. 2% of the surface detached
96 = approx. 4% of the surface detached
94 = approx. 6% of the surface detached
92 = approx. 8% of the surface detached
90 = approx. 10% of the surface detached
85 = approx. 15% of the surface detached
80 = approx. 20% of the surface detached
75 = approx. 25% of the surface detached
70 = approx. 30% of the surface detached
60 = approx. 40% of the surface detached
40 = approx. 60% of the surface detached
20 = approx. 80% of the surface detached
0 = pavement dropped

The mean of the individual values forms a measure of the skin health capacity HV. The comparison of the table values of the measured samples AD shows a slightly increasing tendency of HV of the adhesive-side irradiated samples AC with decreasing gel value. On the other hand, the skin-care capacity of sample D, which was exposed to the back-side irradiation according to the invention, was markedly improved:

The Example shows that by means of back exposure with defined Crosslinking dose generated Vernetzungsientenienten and appropriate adjustment the cross-linking decrease to the transition Adhesive / skin surface a significantly improved skin health while maintaining the necessary cohesiveness and adhesive anchoring with the carrier material can be achieved.

It demonstrate:

1 : Dependence of the cohesion and the adhesion of the gel value, whereby the corresponding decrease of the adhesion capacity at the skin / adhesive interface is accompanied by an increase of the cohesion (residue-free patch removal or reduction of the detachment of the adhesive from the carrier material) with higher gel values or crosslinking energies. Conversely, too low degrees of crosslinking, due to the lower anchoring forces of the adhesive on the transition adhesive / carrier material promote the Klebmasseumspulung / transfer to the skin. Optimal medical products are therefore only available if a high cohesive force prevails at the adhesive / carrier material interface and high adhesion force at the skin / adhesive interface.

2 : Schematic representation of the gel profile in the form of Vernetzngsgrades, in the irradiation of the with an adhesive ( 1 ) coated support material ( 2 ) by a radiation source ( 3 ).

3 : Representation of the gel profile as a function of the irradiation power, at irradiation powers of 50 mJ / cm ² , 25 mJ / cm ² and 10 mJ / cm ² .

Claims (8)

One-sided self-adhesive medical product, characterized in that the adhesive layer has a gel profile, wherein the highest degree of crosslinking prevails at the transition from the carrier material to the adhesive layer (carrier side) and the area with the lowest crosslinking in the region of the application side (adhesive side) is formed, wherein in particular the gel profile is built up by selective radiation-chemical crosslinking with accelerated electrons or UV rays, by irradiation through the support material. Method for analyzing the gel profile of a medical Product according to claim 1, characterized in that the product by means of cryomicrotome in surface parallel Cuts is cut, extracts the cuts of the same depth of cut and from the mass loss in the extraction of the gel value dependent on the depth, is calculated. Method for controlling the crosslinking of adhesives in medical products according to claim 1, characterized in that the one sensor-based Meßssystem for the online registration of the gel value in case of deviations from a given Target value, the crosslinking of the adhesive over the effective radiation power varied. Process for the production of medical products, in which - the Adhesive on a carrier material is applied, - the Adhesive through the carrier material through, irradiated by means of electron beams and / or UV rays becomes. Method according to at least one of the preceding Claims, characterized in that the carrier material consists of one or more layers. Method according to at least one of the preceding Claims, characterized in that as support materials those made of MOPP, BOPP, HDPE, LDPE, polyester, PVC, paper, nonwovens or foams be used. Method according to at least one of the preceding Claims, characterized in that as adhesives Acrylates and rubbers from solution, from dispersion or hotmelt adhesives, which are used preferably filled, colored and / or foamed are. Method according to at least one of the preceding Claims, characterized in that the Irradiation with UV and / or electron beams a crosslinking and / or causes a polymerization of the adhesive.