DE102019203269A1 - Process for the manufacture of fiber materials - Google Patents

Abstract

The invention relates to a method for assembling fiber material objects, the fiber material object being stabilized by an adhesive film in at least one of the assembling steps, the adhesive film comprising a layer of an adhesive for bonding to the fiber material, which is obtainable by I. radical polymerization of the following monomer composition (a) 52 to 88% by weight of one or more acrylic acid esters with linear and / or branched alkyl radicals with 4 to 10 carbon atoms, (b) 2 to 8% by weight of one or more monomers selected from the list from acrylic acid, methacrylic acid, itaconic acid, (c) 10 to 40% by weight of one or more acrylic acid esters with a linear alkyl radical having 12 to 20 carbon atoms, the percentages by weight being based on the monomer composition of components (a), (b) and (c ) are related, II. Subsequent crosslinking of the polymer obtained in the presence of at least one crosslinking reagent containing at least two active crosslinking groups with an equivalent weight EW, based on the crosslinking groups, in the range from 80 to 220 g / eq, which is in an initial amount of (0.005 * | EW |) to ( 0.025 * | EW |) parts by weight, based on 100 parts by weight of the monomer composition, is present in the polymer up to a degree of crosslinking of at least 90%, as well as the use of a corresponding adhesive film for adhesive film for stabilization in at least one of the steps the assembly of fiber material objects.

Description

Composite materials, also known as composite materials or composites, are materials made of two or more materials that are connected to one another. The composite material has different overall properties than the individual components.
Composite materials are widely used in the manufacture of products and components of all kinds, replacing, for example, metals or other plastics. Fiber composite materials are composites in which fibers, fiber braids, fiber fabrics or the like are embedded in a matrix component - often polymer compounds, such as a casting resin, are used for this purpose. Three-dimensional composite materials are often built up in layers by pouring individual layers of the composite material onto them. The embedded fiber system gives such a composite material particular strength.
Fiber composite materials are state of the art. Reference is made to the relevant literature.

In the production of fiber composite materials, the fibers - in particular fiber braids, fiber scrims, fiber fabrics - are often cut into a predefined shape in order to then be potted with the matrix material. For the production of the composites, typically comprised of dry lay-up or preforming processes, for example non-woven fabrics or fabrics (fiber mats) as well as individual fiber strands (so-called rovings) are used. Well-known examples are glass fiber or carbon fiber mats. An early production step then involves cutting the fiber mats before they are placed in a mold in a specific configuration and embedded in the matrix. Often a multiple or large number of fiber mats or the like are layered on top of one another and these “bundles” are then cut in a common step. Then the individual layers must be separated from one another again.

In order to guarantee the mechanical properties of the end product, the raw material must be shaped precisely and without any defects. The material can then be reshaped again, if necessary, which often takes place at an elevated temperature before a polymer matrix and the primary material create the end product.

The cutting of the fiber material object - such as fiber mats, fabrics, fabrics, fleeces, rovings, etc. - is done by various methods, such as cutting blades (cutters), cutting robots, water jet cutting systems or the like. All cutting methods have in common that they often lead to imperfections in the material, for example in particular fiber fraying in the cut edge area. This effect is increased when using blunt knives. Since fiber composite materials are relatively abrasive, the knife service life is usually short. Missing or inadequate fixation on a base or insufficient friction on the base - the layer then slips during cutting - also increases the problem mentioned.
In addition, the fiber material can be overstretched or overstretched; often in a certain critical direction. This effect occurs particularly when using relatively loosely laid or woven fiber materials, when using blunt knives, which can then pull the fibers along, or when handling the fiber material after the actual cutting process, such as separating jointly cut fiber material layers. In particular, there is a deformation of the material because frayed fibers are caught in one another.
If multi-layer bundles of fiber mats or the like are cut in one process step, the individual layers must then be separated from one another again. The frayed fibers are often caught in one another in the area of the cut edge. When the layers are separated, further imperfections can arise in the fiber arrangement of the individual mats, such as the woven structure.

Such imperfections contribute to significant defects in the composite material after the polymer matrix has cured. Optical imperfections at the cut edges and / or outside of these areas, such as those caused, for example, by overstretching the material, are unattractive for the final end product. However, structural weaknesses are much more critical. If the stacked layers are not optimally on top of each other, the design specifications are more difficult to adhere to. In addition, quality measurements have proven that even small imperfections in the fiber material lead to strength losses in the composite material and that this no longer meets the quality requirements. If the composite material is installed in a safety-relevant area - for example in automobile or aircraft construction or for the blades of wind turbines - weaknesses in stability are extremely problematic.

• Zum einen werden Masking Tapes mit einer hinreichenden Haftung / Tack verwendet, die die Fasern im Schneidprozess sicher fixieren. Beim anschließenden Ablösen sorgt eine zu hohe Klebkraft des Tapes auf den Fasern aber zu einer Überstreckung oder Dislokation der Fasern. Im schlimmsten Fall sogar zu Klebmasserückständen auf den Fasern.
• Andererseits werden Masking Tapes verwendet, die sich durch sehr geringe Haftung auf den Fasern auszeichnen und sich rückstandsfrei und ohne Überstreckung oder Dislokation der Fasern ablösen lassen. Die geringe Haftung führt jedoch dazu, dass beim Schneidprozess Fasern nicht sicher fixiert werden können und es so zu Störstellen kommt.
• Einseitige oder doppelseitige Klebebänder werden zudem üblicherweise entweder mit einer Trennbeschichtung und oder einem Trennmaterial dargereicht. Dabei handelt sich es beispielsweise um silikonhaltige Beschichtungen. Diese Stoffe mit anti-Hafteigenschaften können beispielsweise von der Klebmasse auf die Faser übertragen werden und führen später zu einer schlechten Verbindung zwischen Polymermatrix und verstärkendem Fasermaterial oder zu einer Schwächung der Matrix an sich.

In the prior art, attempts have been made to overcome the problems mentioned by using a one-sided adhesive tape (a so-called masking tape) for fixing. The cut then takes place along or through the tape. However, there are three basic problems with using masking tapes:

• On the one hand, masking tapes with sufficient adhesion / tack are used, which securely fix the fibers in the cutting process. When the tape is then detached, if the adhesive strength of the tape on the fibers is too high, the fibers are overstretched or dislocated. In the worst case, even residues of adhesive on the fibers.
• On the other hand, masking tapes are used, which are characterized by very low adhesion to the fibers and can be removed without leaving any residue and without overstretching or dislocating the fibers. However, the low level of adhesion means that fibers cannot be securely fixed during the cutting process, which leads to imperfections.
• One-sided or double-sided adhesive tapes are also usually presented either with a release coating and / or a release material. These are, for example, silicone-containing coatings. These substances with anti-stick properties can, for example, be transferred from the adhesive to the fiber and later lead to a poor connection between the polymer matrix and the reinforcing fiber material or to a weakening of the matrix itself.

In an alternative procedure, the material is fixed to a (cutting) base with a spray adhesive. Disadvantages of this method, however, are negative influences on people and the environment (VOC pollution), the occurrence of extremely flammable, toxic and possibly sensitizing aerosols and the introduction of foreign material into the end product using the method mentioned, since complete subsequent removal of the foreign material is very difficult .

In another procedure, the fiber material to be cut is cut wet using liquid resin or the like. Any excess resin in the soaked material is dabbed off and a release paper (e.g. wax paper) is placed on both sides. One side is fixed to a cutting pad with double-sided tape, and the desired shape is cut through the entire layer structure. Disadvantages are the pollution and the additional processing of hazardous substances, as well as the risk of additional material overstretching.

Furthermore, the bond strength on sensitive substrates can be reduced by means of the wetted surface. An example of this are crepe tapes in which a pearl polymer is used. The wetted surface, and thus also the adhesive strength, has a significantly lower effect on such products, and not all individual fibers can be fixed evenly.

Problems similar to those mentioned above occur not only in the production of composite materials, but always when fiber material systems are cut. For example, cutting wood - sawing, milling or the like - often leads to the formation of splinters at the cut edge, which also leads to optical or structural problems. In addition, the risk of injury increases when using such processed materials. When cutting textiles, fraying often occurs.

The objective task is therefore to reduce the aforementioned problems when cutting fiber materials - in particular, but not only when producing composite materials -, at best even to avoid them.

Because of the weaknesses mentioned that arise when an adhesive tape is used - namely the mentioned unsuitability up to the intensification of the actual problem - the person skilled in the art in search of a solution to the objective problem is led away from the use of adhesive tapes. However, a solution to the problem mentioned unexpectedly arises precisely through the use of a specific adhesive tape.

1. I. radikalische Polymerisation der folgenden Monomerzusammensetzung
   1. (a) 52 bis 88 Gew.-% eines oder mehrerer Acrylsäureester mit linearen und/oder verzweigten Alkylresten mit 4 bis 10 Kohlenstoffatomen,
   2. (b) 2 bis 8 Gew.-% eines oder mehrerer Monomere gewählt aus der Liste aus Acrylsäure, Methacrylsäure, Itaconsäure,
   3. (c) 10 bis 40 Gew.-% eines oder mehrerer Acrylsäureester mit einem linearen Alkylrest mit 12 bis 20 Kohlenstoffatomen,
   wobei die Gewichtsprozentanteile auf die Monomerzusammensetzung aus den Komponenten (a), (b) und (c) bezogen sind, und
2. II. anschließende Vernetzung des erhaltenen Polymerisats in Gegenwart zumindest eines zumindest zwei vernetzungsaktive Gruppen aufweisenden Vernetzungsreagenz mit einem Äquivalentgewicht EW, bezogen auf die vernetzungsaktiven Gruppen, im Bereich von 80 bis 220 g/eq, der in einer Anfangsmenge von (0,005 * |EW|) bis (0,025 * |EW|) Gew.-Teile, bezogen auf 100 Gew.-Teile der Monomerzusammensetzung, im Polymerisat vorliegt, bis zu einem Vernetzungsgrad von mindestens 90 %.

Accordingly, the invention relates to a method for processing fiber material objects, the fiber material object being stabilized by an adhesive film before at least one of the processing steps, the adhesive film comprising a layer of an adhesive for bonding to the fiber material, which is obtainable by

1. I. radical polymerization of the following monomer composition
   1. (a) 52 to 88% by weight of one or more acrylic acid esters with linear and / or branched alkyl radicals with 4 to 10 carbon atoms,
   2. (b) 2 to 8% by weight of one or more monomers selected from the list of acrylic acid, methacrylic acid, itaconic acid,
   3. (c) 10 to 40% by weight of one or more acrylic acid esters with a linear alkyl radical with 12 to 20 carbon atoms,
   wherein the percentages by weight are based on the monomer composition of components (a), (b) and (c), and
2. II. Subsequent crosslinking of the polymer obtained in the presence of at least one crosslinking reagent having at least two active crosslinking groups with an equivalent weight EW, based on the crosslinking active groups, in the range from 80 to 220 g / eq, which in an initial amount of (0.005 * | EW |) Up to (0.025 * | EW |) parts by weight, based on 100 parts by weight of the monomer composition, is present in the polymer, up to a degree of crosslinking of at least 90%.

The equivalent weight EW based on the respective crosslinking-active centers is defined in accordance with the epoxide equivalent weight DIN EN ISO 3001: 1999-11 and indicates the solid content of the substance in question in grams (g) for each active group (eq), i.e. g / eq. | EW | then means the amount without units of the corresponding unit-related (g / eq) equivalent weight.
The degree of crosslinking here relates to the gel value GW determined from the crosslinked samples. This is determined by determining the proportion of polymer still soluble (uncrosslinked) in ethyl acetate after crosslinking by extraction. This method is described in detail in the experimental section.

• - für den Tack (die Anfassklebrigkeit) ≤ 180 mm, besonders bevorzugt ≤ 160 mm (Messung: Rolling-Ball; kleine Wegstrecken bedeutet hohen Tack),
• - und/oder für die Klebkraft auf Glas ≤ 1,5 N/cm, besonders bevorzugt ≤ 0,5 N/cm,
• - insbesondere bei einer Klebkraftzunahme auf Glas von ≤ 20 % (Messung: Klebkraft, „Peel Adhesion“), besonders bevorzugt ≤ 15 % innerhalb von 14 Tagen;
• - für die Kohäson (Messung Scherstandtest) ≥ 6000 min, besonders bevorzugt ≥ 10000 min,
• - für den Mikroscherweg ≤ 15 µm , besonders bevorzugt ≤ 5 µm.

The adhesive used for the process according to the invention has a very high tack and, at the same time, a very low bond strength with very good cohesion. Preferred values are (based on the measurement methods specified in the experimental section):

• - for the tack (the tackiness) ≤ 180 mm, particularly preferably ≤ 160 mm (measurement: rolling ball; short distances mean high tack),
• - and / or for the bond strength on glass ≤ 1.5 N / cm, particularly preferably ≤ 0.5 N / cm,
• - in particular with an increase in bond strength on glass of 20% (measurement: bond strength, “peel adhesion”), particularly preferably 15% within 14 days;
• - for cohesion (measurement of shear resistance test) ≥ 6000 min, particularly preferably ≥ 10000 min,
• - for the microshear travel ≤ 15 µm, particularly preferably ≤ 5 µm.

The adhesive has transparent properties. It is advantageous - but not mandatory - that it is coated on a transparent or translucent carrier material so that the original fiber structure remains visible or recognizable. This makes the cutting process easier.

The invention further relates to the use of an adhesive film for stabilization during the processing of fiber material objects, the adhesive film comprising a layer of an adhesive for bonding to the fiber material, which is as defined above, namely obtainable by radical polymerization according to step I. and subsequent crosslinking according to step II.

Finally, the invention relates to an adhesive film as it is suitable for the method according to the invention and the use according to the invention.

The subclaims relate to advantageous embodiments of the method according to the invention, the use according to the invention or the adhesive film according to the invention.

A “fiber material object” refers to all spatial structures that are, consist of, or include a fiber material. Examples of fiber material objects - in the narrower sense - are scrims, woven fabrics, knitted fabrics, fleeces, textiles, rovings (bundles, strands or multifilament yarns made of filaments arranged essentially in parallel) and the like. Boards - like wooden boards - are made in the In the context of this document, counted to the fiber material objects in the broader sense, even if they differ from the previously mentioned fiber material objects as a rule by a significantly higher rigidity.

Fiber materials can be or comprise individual fibers or a plurality or multiplicity of individual fibers. Fibers can be of natural origin (natural fibers) or of artificial origin (synthetic fibers, man-made fibers). A fiber is a linear, elementary structure that consists of a fiber material and has an outer fiber shape (longitudinal shape: plain, curled; cross-sectional shape: round, angular, etc.). The fiber can be endless or of limited length and is a thin, flexible structure in relation to its length.
Natural fibers can be of animal, vegetable or mineral origin, wood fibers also counting among the natural fibers for the purposes of the present application. Examples of natural fiber materials are wood, raffia, flax, hemp, silk, wool, cotton, jute, kanaf, ramie, sisal, hair, and silicates, not to mention just a few.
Man-made fibers are fibers produced artificially from natural and / or artificial raw materials, in particular polymer fibers. Some, likewise non-limiting examples of chemical fibers are polylactide fibers, polyamide fibers, casein fibers, acetate fibers.
Other artificially produced fiber materials that can be used according to the invention and are used in particular in the production of fiber composites are glass (glass fibers), carbon and carbon-containing materials (carbon fibers, carbon fibers, carbon fibers), ceramics (ceramic fibers), liquid crystal polymers - in particular aramids (aramid fibers), like Kevlar, boron or materials containing boron (boron fibers), basalts (basalt fibers), steel (steel fibers), nylon (nylon fibers).

Adhesive films in the sense of the present application are all essentially flatly extended objects whose extension in two spatial directions (x-direction and y-direction; length and width) is significantly greater than in the third spatial direction (z-direction; thickness). Adhesive films have a layer of adhesive on at least one side. Adhesive films can be single-layer (single layer of adhesive), two-layer (in particular carrier layer and layer of adhesive, adhesive on one side) or multilayer (for example three-layer, layers of adhesive on both surfaces of a carrier material). Adhesive films within the meaning of this document can be designed differently with regard to the x and y directions. Adhesive foils can have regular surface shapes (circle, square, rectangle, ellipse, etc.) or irregular surface shapes. An adhesive film having essentially two parallel longitudinal edges, in which the length is usually significantly greater than the width, is also referred to as an adhesive tape. Sections of adhesive tape are also known as labels. Adhesive foils can also be offered as “diecuts, frame-shaped etc.”. The term “adhesive film” in the sense of the present document includes all possible configurations of such a flat structure. In particular, adhesive tapes and adhesive tape sections are used for the use according to the invention, but the teaching of the invention is not restricted to this.

According to the invention, the term “assembly” of fiber material objects can encompass individual or a plurality of - in particular successive - processing steps. In production and technology, assembly is used to describe any type of division, length division or definition of application-specific molded parts, end pieces and dimensions; the term is used accordingly in this document. In particular, at least one of the assembly steps - that is to say one of the assembly steps - is or includes cutting, such as cutting to length, cutting to size, shape cutting, punching or the like. In one embodiment of the invention, this cutting represents the assembly. The cutting of the fiber material object can according to the invention in particular with a blade - such as a cutter knife -, a punch, a saw or precision saw, a cutting robot, by means of water jets - such as with a special water jet cutting machine -, by means of laser beams - for example with a special laser cutting machine. A combination of two or more of the aforementioned and / or other cutting techniques can also be used. If the term “cutting” is used in the context of this document, the techniques mentioned and the other cutting techniques known from the prior art are subsumed under this.
For the assembly process, in particular the cutting process, it can be advantageous if the fiber material object to be cut or the bundle of fiber material objects lies on a planar, hard surface, such as a ceramic plate, a metal plate, a hard plastic plate or the like.

The method according to the invention has succeeded in reducing or completely avoiding the deformation of the fiber structure and the fiber order or fiber arrangement, the pulling out and kinking of fibers and the fraying and structural damage during assembly, especially when cutting, of fiber material objects. The same applies to the splintering of wood and brittle fiber materials.

The use of a specific adhesive for bonding the adhesive film to the fiber material object was essential for the success of the invention. What is required is an adhesive with high tack and high shear strength, but low adhesive strength on the fiber material object. Tack (also referred to as “tack”) denotes the property of the adhesive to adhere to the substrate with low pressure and short contact times. The shear strength is a measure of the resistance of the adhesive to mechanical stress (tension or compression). The bond strength (adhesion), in turn, denotes the bonding strength of the adhesive layer to the substrate, as it develops after some time. If the adhesion is high, there will be strong binding forces. High tack and high shear strength guarantee process reliability in the method according to the invention or in the use according to the invention. A low adhesion guarantees that the adhesive film can finally be removed again without causing any damage to the fiber material object itself - for example a cut edge in particular - such as pulling out and kinking of fibers that are pulled along by the adhesive and thus causing a fray.

1. (a) 52 bis 88 Gew.-% eines oder mehrerer (Meth-)Acrylsäureester mit linearen und/oder verzweigten Alkylresten mit 4 bis 10 Kohlenstoffatomen,
2. (b) 2 bis 8 Gew.-% eines oder mehrerer Monomere gewählt aus der Liste aus Acrylsäure, Methacrylsäure, Itaconsäure,
3. (c) 10 bis 40 Gew.-% eines oder mehrerer (Meth-)Acrylsäureester mit einem linearen Alkylrest mit 12 bis 20 Kohlenstoffatomen,

wobei die Gewichtsprozentanteile auf die Monomerzusammensetzung aus den Komponenten (a), (b) und (c) bezogen sind. Die Gewichts-Prozente der Komponenten (a), (b) und (c) können sich dabei in bevorzugter Vorgehensweise zu 100 Gew.-% addieren; in Abwandlungen der Erfindung ergeben diese Gewichtsanteile weniger als 100 Gew.-% in Summe, wobei der fehlende Anteil dann durch ein oder mehrere copolymerisierbare Comonomere, wie andere (Meth-)Acrylmonomere oder vinylgruppehaltige Monomere, ergänzt wird.The adhesive used according to the invention is based on a polyacrylate which is formed from the following monomers:

1. (a) 52 to 88% by weight of one or more (meth) acrylic acid esters with linear and / or branched alkyl radicals with 4 to 10 carbon atoms,
2. (b) 2 to 8% by weight of one or more monomers selected from the list of acrylic acid, methacrylic acid, itaconic acid,
3. (c) 10 to 40% by weight of one or more (meth) acrylic acid esters with a linear alkyl radical with 12 to 20 carbon atoms,

wherein the percentages by weight are based on the monomer composition of components (a), (b) and (c). The weight percentages of components (a), (b) and (c) can add up to 100% by weight in a preferred procedure; In modifications of the invention, these proportions by weight result in a total of less than 100% by weight, the missing proportion then being supplemented by one or more copolymerizable comonomers, such as other (meth) acrylic monomers or monomers containing vinyl groups.

(Meth) acrylic monomers, which are very preferably used as monomer component (a), include acrylic and methacrylic acid esters with alkyl groups consisting of 1 to 10 carbon atoms. In an advantageous procedure, acrylic monomers are preferred to methacrylic monomers for monomer component (a). The monomers of component (a) are particularly preferably chosen such that their corresponding homopolymer has a static glass transition temperature T _G of <-30 ° C. Specific examples of corresponding compounds of component (a) are - without wishing to be unnecessarily restricted by this list - n-butyl acrylate, n-pentyl acrylate, n-hexyl acrylate, n-heptyl acrylate, n-octyl acrylate, n-nonyl acrylate, 2-ethylhexyl acrylate, 2-propyl heptyl acrylate and isooctyl acrylate.

(Meth) acrylic monomers, which are very preferably used as monomer component (c), include acrylic and methacrylic acid esters with a linear alkyl radical with at least 12 carbon atoms. The monomers of component (c) are advantageously chosen such that their corresponding homopolymer has a static static glass transition temperature of at least 30.degree. Specific examples are - without wishing to be unnecessarily limited by this list - n-lauryl acrylate and stearyl acrylate.

An adhesive particularly suitable according to the invention is attributable to a monomer composition consisting of 70 to 80% by weight ethylhexyl acrylate, 16 to 27% by weight stearyl acrylate and 3 to 6% by weight acrylic acid (also referred to as adhesive K +); preferably consisting of 76% by weight of 2-ethylhexyl acrylate, 20% by weight of stearyl acrylate and 4% by weight of acrylic acid (also referred to as K ++ adhesive).

In principle, all free-radical or free-radical-controlled polymerizations can be used to prepare the copolymers according to the invention, as can combinations of different polymerization processes. It can in principle be polymerized in solution or in the melt. In addition to conventional free radical polymerization, z. B. the ATRP, the nitroxide / TEMPO-controlled polymerization or the RAFT process called, so in particular those processes that allow a control of the chain lengths or the polymer architecture. The usual initiators known for acrylates can be used as free radical initiators for the free radical polymerization. Examples of radical sources are peroxides, hydroperoxides and azo compounds. Reference is made to the general state of knowledge on this.
The result of the polymerization in step I, i.e. the totality of the polyacrylate macromolecules obtained, is also referred to as “polymer” in the context of this document (regardless of whether any solvent is still present or not; the polymer can therefore still comprise solvent or be solvent-free be).

The number average molar mass M _{n of} the polyacrylate copolymers obtained in this way is, before crosslinking, preferably between about 10,000 and about 600,000 g / mol, more preferably between 30,000 and 400,000 g / mol, particularly preferably between 50,000 g / mol and 300,000 g / mol .

In order to set the properties required according to the invention, the adhesive must also have a certain degree of crosslinking. This can be achieved if at least one crosslinking reagent having at least two crosslinking-active groups (also referred to as “crosslinker” for short) is used in a certain amount, based on the crosslinking-active groups. The at least one crosslinking reagent is present in an initial amount in a specific range, as indicated below. The addition of the crosslinker can in principle take place at different times; What is essential is the presence of the amount of crosslinking agent at the beginning of crosslinking (initial amount). As a result of the crosslinking reaction, this amount will decrease in the course of the crosslinking.
The equivalent weight EW, based on the groups active in crosslinking, is in the range from 80 to 200 g / eq. The amount of crosslinker advantageously used according to the invention is then in a range from (0.005 * | EW |) to (0.025 * | EW |) parts by weight, per 100 parts by weight of the monomer composition, more preferably in a range of (0 .01 * | EW |) to (0.02 * | EW |) parts by weight, per 100 parts by weight of the monomer composition. For a crosslinker named as an example with an equivalent weight of 100 g per crosslinking-active group (EW = 100 g / eq), 0.5 to 2.5 parts by weight, preferably 1.0 to 2 parts by weight, would be according to the invention . -Parts of monomer composition to be used.
If two or more crosslinkers are used at the same time, the calculation formula for calculating the amount of crosslinker must be adapted so that the amount of active crosslinking groups is again in the relevant range; instead of | EW | the sum Σ (x _v * | EW _v |) over all crosslinkers present would then have to be inserted and the formula to be solved accordingly [xv = proportion of the respective crosslinker V in%, | EW _v | = Equivalent weight of the respective crosslinker V].
The amount of the crosslinking-active groups is defined by the amount based on the equivalent weight.

The at least one crosslinker [the one or more crosslinkers] must be present in the polymer obtained in step I at the beginning of the crosslinking reaction, in particular homogeneously distributed and in particular in the initial amount. The step of introducing the crosslinker is initially not limited in time in this regard. In one variant of the invention, the at least one crosslinker - provided it is stable enough - is added to the reaction mixture during the polymerization, and / or it is added to the polymer obtained after the polymerization. It is also conceivable to add it to the monomer mixture before the polymerization, but this will often be impractical due to the heat sensitivity of a large number of crosslinkers and the prevailing polymerization conditions. It is also possible to divide the crosslinker into several batches and to add these or, if several crosslinkers are present, these several crosslinkers in several steps, it being possible for these several addition steps to take place during and / or after the polymerization.
It is particularly preferred to add one or more batches after the polymerization to the polymer obtained in step I, and particularly preferably shortly before the further processing of the polymer (such as shaping into a layer) and the subsequent crosslinking.

In the case of reactive crosslinkers in particular - such as those described below as preferred crosslinkers - it is advisable to add them to the polymer shortly before crosslinking, in particular shortly before shaping into a layer (see below), and to distribute them homogeneously in it. Polymers with mixed-in reactive crosslinkers may have processing times (“pot lives”) of a few hours, within which further processing - in particular the shaping into a layer - should take place. Processing within 2 hours is advisable for the crosslinkers listed below as preferred. The pot life is due to the fact that the crosslinking reaction starts after the addition of the crosslinker and already takes place under the prevailing conditions - such as room temperature 23 ° C - but to such a small extent that homogeneous and even processing is still guaranteed. After the pot life has expired, the cohesion begins to increase to such an extent that further processing becomes problematic and the layer formation becomes, for example, irregular (for example "specks" or "nodules" can be found in the adhesive layer).

Before the crosslinking or before the essential part of the crosslinking of the adhesive, the polymer is formed into a layer (after the addition of the crosslinker, the crosslinking may already take place to a small extent, which is harmless as long as the resulting increase in cohesion does not hinder the uniform layer formation). The coating can be carried out from solution or from the melt using the known techniques. If the polymerization was carried out in solution, the solvent or a Part of it can be removed before coating. The coating can be done on the later carrier of the adhesive film or on a temporary carrier material (so-called process liner), which is subsequently - this can be done before or after the crosslinking - re-coated - for example re-laminated - on the final carrier. The adhesive is optionally freed from solvent after coating, but before or during crosslinking.

The crosslinking in step II during the production of the adhesive can in principle already take place at room temperature, but is promoted in particular by the supply of heat, for example in the range from 50.degree. C. to 150.degree. As a rule, higher temperatures accelerate the crosslinking process; however, the temperature limit results from the temperature resistance of the respective adhesive and / or the carrier material. In contrast, moderately increased temperatures can lead to a somewhat longer-lasting crosslinking, but possibly a more uniform crosslinking profile.
The crosslinking can take place simultaneously with the drying of the polymer layer produced (adhesive layer), that is to say with the removal of solvent. The drying phase usually lasts from a few seconds or minutes to a few hours. Usual drying times (residence times) in the tunnel dryer are about a few seconds to a few minutes, about 30 to 60 s, in the case of adhesive compositions to be dried of up to about 100 μm. Drying times in hanging drying can range from a few minutes to more than 15 minutes, for example.
Up to the desired degree of crosslinking, it can be advantageous to allow the adhesive layer to be postcrosslinked for some time, for example several hours up to a few days. The crosslinking is carried out up to a crosslinking conversion of at least 90%, preferably at least 95% (so that at least 90%, preferably at least 95% of the polymer is no longer soluble in ethyl acetate in the gel index test). A gel value of more than 95% is accordingly regarded as essentially complete crosslinking.

Crosslinkers containing epoxy groups are preferably used. The equivalent weight EW, based on the groups active in crosslinking, then corresponds to the epoxide equivalent weight EEW. The crosslinkers containing epoxy groups which are preferably used are therefore those in which the epoxy equivalent weight is in a range from 80 to 220 g / eq.

• • N,N,N',N'-tetrakis(2,3-epoxypropyl)-m-xylen-a,a'-diamin (CAS 63738-22-7, Tetraglycidyl meta-Xylendiamin),
• • N,N,N',N'-Tetrakis(2,3-epoxypropyl)cylohexan-1,3-dimethylamin (CAS 65992-66-7, Tetraglycidylcylohexandimethylamine), beide genannten Vernetzer mit einem EEW von ca. 100 g/eq (je nach Charge 95 bis 110 g/eq), dann jeweils einsetzbar in einer Menge von 0,50 bis 2,50 Gew.-Teile, bevorzugt 1,00 bis 2,00 Gew.-Teile auf 100 Gew.-Teile Monomerzusammensetzung, sowie
• • ein Epoxidharz aus Bisphenol A und Epichlorhydrin [(Poly)Bisphenol A-co-epichlorhydrin; CAS 25068-38-6] gemäß der allgemeinen Formel
  
  wobei n gewählt ist aus den natürlichen Zahlen einschließlich 0, insbesondere derart gewählt, dass das EEW der eingesetzten Vernetzercharge gleich ca. 185 g/eq (je nach Charge 182 bis 190 g/eq) ist, dann jeweils einsetzbar in einer Menge von 0,92 bis 4,63 Gew.-Teile, bevorzugt 1,85 bis 3,70 Gew.-Teile auf 100 Gew.-Teile Monomerzusammensetzung,
• • oder dessen hydrierte Form [4,4'-(1-methylethylidene)bis-cyclohexanol, Polymer mit 2-(chloromethyl)oxiran, CAS 30583-72-3] gemäß der allgemeinen Formel
  
  wobei n gewählt ist aus den natürlichen Zahlen einschließlich 0, insbesondere derart gewählt, dass das EEW der eingesetzten Vernetzercharge gleich ca. 210 g/eq (je nach Charge 205 bis 215 g/eq) ist, dann jeweils einsetzbar in einer Menge von 1,05 bis 5,25 Gew.-Teile, bevorzugt 2,10 bis 3,15 Gew.-Teile auf 100 Gew.-Teile Monomerzusammensetzung,

Preferred crosslinkers which can be used very advantageously, in particular also in conjunction with the preferred adhesives K + and K ++, are

• • N, N, N ', N'-tetrakis (2,3-epoxypropyl) -m-xylen-a, a'-diamine (CAS 63738-22-7, tetraglycidyl meta-xylenediamine),
• • N, N, N ', N'-Tetrakis (2,3-epoxypropyl) cyclohexane-1,3-dimethylamine (CAS 65992-66-7, tetraglycidylcylohexanedimethylamine), both of the mentioned crosslinkers with an EEW of approx. 100 g / eq (depending on the batch 95 to 110 g / eq), then each usable in an amount of 0.50 to 2.50 parts by weight, preferably 1.00 to 2.00 parts by weight, per 100 parts by weight of monomer composition , such as
• • an epoxy resin made from bisphenol A and epichlorohydrin [(poly) bisphenol A-co-epichlorohydrin; CAS 25068-38-6] according to the general formula
  
  where n is selected from the natural numbers including 0, in particular selected such that the EEW of the crosslinker batch used is equal to approx. 185 g / eq (depending on the batch 182 to 190 g / eq), can then be used in an amount of 0, 92 to 4.63 parts by weight, preferably 1.85 to 3.70 parts by weight per 100 parts by weight of monomer composition,
• • or its hydrogenated form [4,4 '- (1-methylethylidene) bis-cyclohexanol, polymer with 2- (chloromethyl) oxirane, CAS 30583-72-3] according to the general formula
  
  where n is selected from the natural numbers including 0, in particular selected in such a way that the EEW of the crosslinker batch used is equal to approx. 210 g / eq (depending on the batch 205 to 215 g / eq), can then be used in an amount of 1, 05 to 5.25 parts by weight, preferably 2.10 to 3.15 parts by weight per 100 parts by weight of monomer composition,

The adhesive film used according to the invention comprises at least one layer of the adhesive in question and a carrier layer. The simplest embodiment of the invention is accordingly a single-sided, two-layer adhesive film made of the aforementioned layers. In principle, according to the invention - depending on the application - multilayer and double-sided adhesive films can also be implemented, for example a double-sided adhesive product made from a carrier film coated on both sides with adhesive. In such a double-sided adhesive product, both layers of adhesive can be formed by the adhesive of the invention, or only one of the layer of adhesive is an adhesive of the invention and the other layer of adhesive is a different adhesive. Double-sided adhesive tapes are usually covered on at least one side with a temporary separating layer, a so-called release liner, for handling and are therefore more likely to be used in cases where the issues presented below with regard to the release agent used play no or only a minor role.

The material of the carrier film used can in principle be freely selected. Films such as, for example, made of polyamide, polyurethane or polyvinyl chloride, polyolefins or polyester, preferably a polyester made of PET (polyethylene terephthalate), are suitable as the carrier film. The film itself can in turn consist of several individual layers, for example of layers coextruded to form a film.
In addition to polyolefins, copolymers of ethylene and polar monomers such as styrene, vinyl acetate, methyl methacrylate, butyl acrylate or acrylic acid are suitable. It can be a homopolymer such as polyethylene [high density polyethylene (HDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE)] or a copolymer of ethylene or another olefin such as propene, butene, hexene or octene [for example linear polyethylene low density (LLDPE)]. Polypropylenes are also suitable (for example polypropylene homopolymers, polypropylene random copolymers or polypropylene block copolymers). A transparent or translucent carrier film is preferably used in order to be able to see the processing area of the fiber material object through the applied adhesive film, which simplifies the processing steps - for example precisely positioned cutting. A carrier film based on polyester, in particular made of polyethylene terephthalate, has proven to be particularly advantageous.

It is advantageous if the carrier film for anchoring the pressure-sensitive adhesive layer is at least on the side to which the adhesive layer is applied - in the embodiments in which an adhesive layer is provided on both sides of the carrier film, on one or both of its sides, preferably at least on the side on which the adhesive used according to the invention is provided - was previously etched. One way of roughening and chemically modifying the polymer structure is through wet-chemical etching of the carrier material. In general, the anchoring of the PSA can be improved by roughening the carrier material. In addition to etching, pretreatment can also be carried out in other ways. In order to improve the anchoring, the carrier materials can be physically and chemically pretreated. For the physical treatment, the film is preferably treated with flame or corona or plasma. However, there is always the risk of damage to the back of the carrier, which can be disadvantageous for the method according to the invention in certain applications. For chemical pretreatment, the carrier material is provided with a primer. Suitable primer materials are e.g. Reactive primer. However, this method in turn has the disadvantage that the chemicals used can have a detrimental effect on the quality of a fiber composite material. Etching is therefore the preferred pre-treatment method.

The adhesive film used according to the invention and in particular the carrier used for this purpose are very advantageously free of release agents. Release agents (also referred to as release agents) are anti-adhesive substances - such as in particular silicones, fluorosilicon compounds, polydimethylsiloxanes, release agents based on long-chain alkyl groups (for example carbamates - such as polyvinyl stearyl carbamates, polyvinyl octadecyl cabamates -, caramides - such as polyethyleneimine stearyl carbamides - such as chromium complexes of C14 to C28 fatty acids, stearyl copolymers etc .; if necessary with additives such as titanium dioxide), acrylic polymers with perfluorinated alkyl groups, or other substances with low surface energy - and are regularly used as a back coating or back coating of carrier materials for single-sided adhesive tapes or used as a coating for so-called release liners for double-sided adhesive tapes in order to avoid (permanent or strong) sticking of the adhesive layer on the back of the underlying layer when winding the adhesive film strip into a roll, and to avoid the problem To facilitate the removal of wound adhesive film strips or to enable them at all. Such materials, in particular silicones and silicone-containing materials, however, often adversely affect the properties and reliability of fiber composite materials, since they could, for example, migrate into the matrix and / or react with it, and should therefore be avoided as far as possible. The use of the adhesive composition used according to the invention nevertheless makes it possible to wind the adhesive film strips into a roll and to easily unroll them again even without coating the back of the carrier material.

The thickness of the carrier used can be chosen favorably depending on the application; carrier foils with a thickness of about 35 to 75 μm are advantageous for one-sided adhesive, in particular two-layer adhesive films, and carrier foils with a thickness of approximately 35 to 75 μm and for double-sided adhesive, especially three-layer adhesive films (without taking into account a possible liner) Thickness of 12 to 75 µm highlighted.
The thicknesses of the adhesive layers can also be varied in relation to the application; typical layer thicknesses are up to 100 μm, advantageously approximately 50 μm.

The adhesive film is used in the method according to the invention or in the use according to the invention to maintain the structure, in particular the fiber layer or fiber arrangement, when processing the fiber material object, in particular when cutting the fiber material object. Here, for example, an adhesive film strip - also referred to as adhesive tape - is stuck in the cutting direction onto the area of the fiber material object to be cut and then the adhesive film strip is cut through together with the fiber material object. The adhesive film strip stabilizes and supports the fiber material object, so that there is a clean cut edge with a smooth and regular cut.

In a very advantageous embodiment of the invention, the use of the adhesive film is temporary. For this purpose, the adhesive film is applied to the fiber material object, such as the fiber mat, before the structurally damaging processing step (s) - for example including a cutting process -, in particular - during a cutting process - as shown above. Then the processing step (s) can be carried out with reduced or avoided damage to the fiber material object. After the processing step (s), the adhesive film is removed again, in particular peeled off. Due to the special choice of adhesive, there is also no damage to the fiber material object during removal, in particular no pulling, fraying or kinking of fibers, no ladder formation or the like, as has regularly been the case with the use of adhesive films not designed according to the invention was watching. Instead, the processing point - in particular a cut seam - is largely, in many cases even completely free of damage and defects.

During a cutting process, parts of the adhesive film strip used remain on the two cut products and each form a common cut edge with them. It is very advantageous to proceed in that these adhesive film strip parts are carefully peeled off essentially in the direction of the cut edge in order to make the load on the cut edge itself as low as possible. To this end, it is advantageous to equip the adhesive film strip used with the adhesive layer only in the middle, that is to say to leave it free of adhesive on one or both longitudinal edges. Such adhesive-free areas on one or both longitudinal edges of the adhesive tape can be, for example, a few millimeters to a few centimeters. Alternatively, it is possible to subsequently equip the adhesive film strip with adhesive-free gripping aids which can extend over the entire length of the adhesive strip or can be provided in the form of individual local gripping tabs. Such gripping aids - for example made of paper strips, film strips or the like - can for example be glued under the outer edge of the adhesive to the longitudinal edges of the adhesive film strip, or they can also be applied to the carrier film from above.

According to the invention, not only can individual fiber material objects be processed, in particular cut, with the method according to the invention, but also bundles of a plurality or multiplicity in particular fiber material objects placed on top of one another. The same applies to the use according to the invention. For example, appropriately dimensioned blades, but especially water jet cutting or laser cutting, can be used for cutting such bundles.
Advantageously, in the area of the processing points, in particular interfaces, each individual layer is then stabilized with a single-sided adhesive film and processed, in particular cut, according to the method according to the invention or the use according to the invention and their special designs. In an alternative procedure, a double-sided adhesive film equipped on both sides with an adhesive according to the invention is glued in in the area of the processing points, in particular interfaces, between two fiber material objects lying on top of one another, in order to increase the stabilization.

The method according to the invention and the use according to the invention are particularly suitable for cutting fiber mats (individual or fiber mat bundles), in particular in the production of fiber composite materials, for example those that are themselves further processed in automobile construction, in aircraft construction, in shipbuilding and boat building the manufacture of blades for wind turbines, etc. As mentioned above, imperfections in the fiber material objects in the composite material ultimately produced from them lead to weak points which are intolerable, especially in safety-related use, as in the aforementioned areas of application. In the case of such fiber materials, damage by the process according to the invention and by the use according to the invention could be completely avoided.

For the production of fiber composite materials, the processed - in particular cut - fiber material objects in one embodiment of the invention are cast into a matrix in at least one further processing step. Duromers (thermosetting plastics, synthetic resins), elastomers and / or thermoplastics, for example, are suitable as matrix materials. Duromers and elastomers are usually used in liquid form. Thermoplastics are usually softened or liquefied at elevated temperature or dissolved in a solvent and then used to impregnate the fiber material objects. Due to the different properties of the matrix materials used, fiber composites with different mechanical properties can be produced. Duroplastic synthetic resins usually lead to rather brittle products, elastomers can be used to produce elastic products, and thermoplastics usually lead to thermoformable products.

1. I. radikalische Polymerisation der folgenden Monomerzusammensetzung
   1. (a) 52 bis 88 Gew.-% eines oder mehrerer Acrylsäureester mit linearen und/oder verzweigten Alkylresten mit 4 bis 10 Kohlenstoffatomen,
   2. (b) 2 bis 8 Gew.-% eines oder mehrerer Monomere gewählt aus der Liste aus Acrylsäure, Methacrylsäure, Itaconsäure,
   3. (c) 10 bis 40 Gew.-% eines oder mehrerer Acrylsäureester mit einem linearen Alkylrest mit 12 bis 20 Kohlenstoffatomen,
   wobei die Gewichtsprozentanteile auf die Monomerzusammensetzung aus den Komponenten (a), (b) und (c) bezogen sind,
2. II. anschließende Vernetzung des erhaltenen Polymerisats in Gegenwart zumindest eines zumindest zwei vernetzungsaktive Gruppen aufweisenden Vernetzungsreagenz mit einem Äquivalentgewicht EW, bezogen auf die vernetzungsaktiven Gruppen, im Bereich von 80 bis 220 g/eq, der in einer Anfangsmenge von (0,005 * |EW|) bis (0,025 * |EW|) Gew.-Teile, bezogen auf 100 Gew.-Teile der Monomerzusammensetzung, im Polymerisat vorliegt, bis zu einem Vernetzungsgrad von mindestens 90 %.

The invention further provides an adhesive film suitable for the method according to the invention or the use according to the invention, comprising at least one layer of an adhesive which can be obtained by

1. I. radical polymerization of the following monomer composition
   1. (a) 52 to 88% by weight of one or more acrylic acid esters with linear and / or branched alkyl radicals with 4 to 10 carbon atoms,
   2. (b) 2 to 8% by weight of one or more monomers selected from the list of acrylic acid, methacrylic acid, itaconic acid,
   3. (c) 10 to 40% by weight of one or more acrylic acid esters with a linear alkyl radical with 12 to 20 carbon atoms,
   where the percentages by weight are based on the monomer composition of components (a), (b) and (c),
2. II. Subsequent crosslinking of the polymer obtained in the presence of at least one crosslinking reagent having at least two active crosslinking groups with an equivalent weight EW, based on the crosslinking active groups, in the range from 80 to 220 g / eq, which in an initial amount of (0.005 * | EW |) Up to (0.025 * | EW |) parts by weight, based on 100 parts by weight of the monomer composition, is present in the polymer, up to a degree of crosslinking of at least 90%.

Furthermore, the remarks already made regarding this adhesive and the adhesive film comprising this adhesive layer apply.

• - Eine Klebefolie, bei der eine wie vorstehend definierte Klebemasse auf zumindest einer Seite einer transparenten Polyethylenterephthalat-Trägerschicht aufgebracht ist. Die Trägerschicht ist auf zumindest der Oberfläche, die zu der Klebmassenschicht gewandt ist, geätzt.
• - Eine Klebefolie wie hiervor beschrieben, bei der aber auf beiden Seiten einer beidseitig geätzten Polyethylenterephthalat-Trägerschicht eine jeweilige Klebmassenschicht aufgebracht ist.
• - Eine Klebefolie wie zuvor beschrieben, die silikonfrei, carbamatfrei und frei von anderen Trennmitteln (siehe hierzu weiter oben) ist. Dies betrifft sowohl die Klebmasse, die keine solchen Stoffe als Additive oder in sonstiger Form aufweist. Dies betrifft auch die Trägerfolie, die keine entsprechende Trennbeschichtung und keinen entsprechenden Trennlack aufweist. Insbesondere liegt auch auf keiner der Seiten des Klebebandes ein Releaseliner vor.
• - Ein Klebeband als in Längsrichtung ausgedehnter Streifen einer wie im Rahmen dieser Schrift beschrieben Klebefolie, mit definierter Breite und im Wesentlichen parallel verlaufenden Längskanten.
• - Ein Klebeband wie hiervor beschrieben, wobei auf mit Klebmasse ausgerüsteten Oberfläche des Trägermaterials an zumindest einer der Längskanten, bevorzugt an beiden Längskanten, ein klebmassenfreier Bereich vorgesehen ist. Dieser Bereich kann im Wesentlichen parallel zur entsprechenden Klebebandkante verlaufe (also die Kante der entsprechend eingerückten Klebemassenschicht verläuft dann parallel zur Klebebandkante). Die Einrückung kann beispielsweise einige Millimeter oder einige Zentimeter betragen und als „Anfasser“ beziehungsweise „Abzugshilfe“ bei der Demontage von dem Fasermaterialobjekt dienen (siehe hierzu weiter oben). Bei einseitig mit Klebmassenschicht ausgerüsteten Klebebändern kann ein solcher klebmassenfreier Bereich an einer der Längskanten, insbesondere an beiden Längskanten vorgesehen sein. Bei doppelseitigen Klebebändern können klebmassenfreie Bereiche an einer oder an beiden Längskanten und auf einer oder auf beiden Trägeroberflächen vorgesehen sein.

Reference is once again made explicitly to the following advantageous embodiments according to the invention:

• - An adhesive film in which an adhesive composition as defined above is applied to at least one side of a transparent polyethylene terephthalate carrier layer. The carrier layer is etched on at least the surface facing the adhesive layer.
• An adhesive film as described above, but in which a respective adhesive layer is applied to both sides of a polyethylene terephthalate carrier layer etched on both sides.
• - An adhesive film as described above that is silicone-free, carbamate-free and free of other release agents (see above). This applies both to the adhesive, which does not contain any such substances as additives or in any other form. This also applies to the carrier film, which has no corresponding release coating and no corresponding release lacquer. In particular, there is also no release liner on either side of the adhesive tape.
• - An adhesive tape as a longitudinally extended strip of an adhesive film as described in the context of this document, with a defined width and essentially parallel longitudinal edges.
• An adhesive tape as described above, an adhesive-free area being provided on the surface of the carrier material equipped with adhesive on at least one of the longitudinal edges, preferably on both longitudinal edges. This area can run essentially parallel to the corresponding edge of the adhesive tape (that is to say the edge of the correspondingly indented layer of adhesive then runs parallel to the edge of the adhesive tape). The indentation can be a few millimeters or a few centimeters, for example, and serve as a “handle” or “pull-off aid” when dismantling the fiber material object (see above). In the case of adhesive tapes provided with a layer of adhesive on one side, such an adhesive-free area can be provided on one of the longitudinal edges, in particular on both longitudinal edges. In the case of double-sided adhesive tapes, areas free of adhesive mass can be provided on one or on both longitudinal edges and on one or on both carrier surfaces.

Finally, the invention relates to an adhesive tape wound into a roll (mathematically more precisely: an Archimedean spiral), one or both sides of which is provided with a layer of an adhesive according to the invention. The adhesive tape can have any design as shown in this document. In particular, no release coating and no release material (such as a silicone-containing or silicone-coated release film or release paper) is provided between the individual winding layers. Usually, double-sided adhesive tapes in particular are provided with such a release liner on at least one side before they are wound up in order to enable the roll to be unwound again (since the layers lying one on top of the other, in particular when two layers of adhesive are placed on top of one another, would otherwise not be separated from one another that a layer of the adhesive of the invention can easily be peeled off from one another again from a non-etched surface of the carrier material and even two superimposed layers of the adhesive of the invention. Therefore, when winding into a roll, both with adhesive tapes equipped on one side with the adhesive of the invention and with two-sided Adhesive tapes equipped with the adhesive of the invention surprisingly do not have release layers.

Experimental part

Reference and measurement methods

Information on the parameters mentioned in this document and measurements of the parameters mentioned relate to the methods given below, unless otherwise stated in detail.

molar mass

The figures for the number average molar mass Mn in this document relate to the determination by gel permeation chromatography (GPC). The determination is carried out on 100 µl clear-filtered sample (sample concentration 4 g / l). Tetrahydrofuran with 0.1% by volume of trifluoroacetic acid is used as the eluent. The measurement takes place at 25 ° C.
A column type PSS-SDV, 5 µm, 103 Å, 8.0 mm x 50 mm (information here and in the following in the order: type, particle size, porosity, inner diameter, length; 1 Å = 10 ^-10 m) is used as the guard column. used. A combination of PSS-SDV columns, 5 μm, 10 ³ Å, 10 ⁵ Å and 10 ⁶ Å each measuring 8.0 mm × 300 mm is used for separation (columns from Polymer Standards Service; detection using a Shodex RI71 differential refractometer ). The flow rate is 1.0 ml per minute. The calibration takes place at Polyacrylates against PMMA standards (polymethyl methacrylate calibration) and otherwise (resins, elastomers) against PS standards (polystyrene calibration).

Glass transition temperature

Information on the glass transition temperature is based in each case on the determination by means of dynamic differential calorimetry (DSC; differential scanning calorimetry) DIN 53765: 1994-03 , namely to the local glass transition temperature value Tg.

Thickness measurement

The thicknesses of foils (carrier foils), adhesive layers and adhesive tapes were measured using a commercially available thickness measuring device from SIOS, the display accuracy set to 0.01 μm. Test climate: temperature 23 ± 1 ° C, rel. Humidity 50 ± 5%

Peel adhesion

The test of the peel strength (bond strength) was based on the PSTC-1 method (Test Methods for Pressure Sensitive Adhesive Tapes, 15th Edition; publisher: Pressure Sensitive Tape Council, Northbrook (Illinois), USA).
A 2 cm wide strip of the pressure-sensitive adhesive tape is bonded to the test substrate - here a cleaned, fat-free glass plate (float glass; air side) - by rolling it over twice using a 4 kg roller.
Identical samples were obtained within 1 minute after rolling on ("immediately") and after a storage time of 14 days after rolling on ("14 days"; storage in standard climate temperature 23 ± 1 ° C, 50 ± 5% rel. Humidity) measured as follows.
The plate is clamped in and the self-adhesive strip is peeled off at its free end on a tensile testing machine at a peel angle of 180 ° at a speed of 300 mm / min, and the force required for this is determined. Test climate: temperature 23 ± 1 ° C, 50 ± 5% rel. Humidity. The measurement results are given in N / cm and averaged over three measurements (arithmetically). The value is given as KKS (bond strength steel).

Tackiness ("Rolling Ball Tack")

• - Verwendung von Edelstahl-Kugellagerkugeln (Edelstahl 1.4401), Durchmesser 7/16 Zoll, Masse 5,7 g
• - Vorbereitung der Kugeln: Gründliche Reinigung mit Zellstoff und Aceton; die sauberen Kugeln werden vor der Messreihe für 15 min in einem Acetonbad gelagert (Kugeln sind vom Aceton vollständig umgeben); mindestens 30 min vor Beginn der Messung werden die Kugeln dem Acetonbad entnommen und zum Trocknen und Konditionieren offen im Normalklima (23 ± 1 °C, 50 ± 5 % rel. Feuchte) gelagert
• - Jede Kugel wird nur für eine Messung verwendet.

The so-called “rolling ball tack” was measured as a measure of the tack with a very short contact time (of the tack).
The rolling ball tack was determined using the PSTC-6 method (Test Methods for Pressure Sensitive Adhesive Tapes, 15th Edition; publisher: Pressure Sensitive Tape Council, Northbrook (Illinois), USA), with the following modifications:

• - Use of stainless steel ball bearing balls (stainless steel 1.4401), diameter 7/16 inches, mass 5.7 g
• - Preparation of the balls: thorough cleaning with cellulose and acetone; the clean spheres are stored in an acetone bath for 15 min before the series of measurements (spheres are completely surrounded by acetone); At least 30 minutes before the start of the measurement, the spheres are removed from the acetone bath and stored in the open in a normal climate (23 ± 1 ° C, 50 ± 5% relative humidity) for drying and conditioning
• - Each sphere is only used for one measurement.

An approximately 30 cm long strip of the adhesive tape was fastened horizontally on the test plane with the adhesive side up under tension. For the measurement, the steel ball was accelerated by rolling down a 65 mm high ramp (angle of inclination: 21 °) in the gravitational field of the earth (test climate: temperature 23 ± 1 ° C, 50 ± 5% relative humidity). The steel ball was directed from the ramp directly onto the adhesive surface of the sample. The distance covered on the adhesive until the ball came to a standstill was measured. The length of the taxiway determined in this way serves as an inverse measure of the tack of the self-adhesive (that is, the shorter the taxiway, the higher the tack, and vice versa). The respective measured value resulted (as length specification in mm) from the (arithmetic) mean of five individual measurements on five different strips of the adhesive tape.

Micro shear path

The measuring arrangement corresponds to that in 4th of the WO 2017/042221 A ; incorporated into this disclosure by reference; the reference numerals there are used below.
From the adhesive film to be tested, 10 mm × 50 mm large pieces of surface were cut and the adhesive film sample (71) obtained in this way with the adhesive-coated side onto a polished, temperature-controllable, 13 mm wide steel test plate (72) cleaned with acetone (blank: material no 1.4301 according to DIN EN 10088-2 ; Roughness approx. 50 nm, then polished and cleaned with acetone; Acetone removed by evaporation for five minutes) glued in such a way that the longitudinal direction of the adhesive film pattern was aligned in the transverse direction of the steel plate, the bond area had dimensions I xb = 13 mm x 10 mm and the adhesive film had the steel plate on one side by a piece of length z = 2 mm towered over. To fix it, the adhesive film was then rolled over six times with a 2 kg steel roller at a speed of 10 m / min. On the side of the adhesive film (71) facing away from the steel plate (72), the adhesive tape (71) was flush with the edge protruding beyond the steel plate by the length z with a stable adhesive strip (73) (dimensions 4 mm x 25 mm; carrier 190 µm thick PET film), which served as a support for a displacement sensor (not shown). The arrangement prepared in this way was suspended vertically in such a way that the piece of length z of the adhesive film pattern (71) projecting beyond the steel plate (72) pointed upwards. The steel test plate (72) with the bonded adhesive film sample (71) was tempered to 40 ° C. and the adhesive tape sample (71) to be measured at the lower end by means of a clamp (74) (own weight 6.5 g) at time to = 0 loaded a weight (75) of 100 g. The deformation of the specimen under shear was measured over a period of 15 minutes (starting at to) at a temperature of 40 ° C. and a relative humidity of 50 ± 5% using the displacement sensor.
The shear distance after 15 min (maximum value; downward travel of the upper edge of the sample during the measurement) is given as the result in µm. The shear path measured in this way is a quantitative measure of the state of crosslinking of the measured sample.
After the specified test duration of 15 minutes, the weight (75) is removed and the sample is given another 15 minutes to relax. The upper edge of the sample moves upwards. The difference between the position of the upper edge of the specimen when the weight was removed (75) and its position after relaxation for 15 minutes is given as the negative distance in µm.

Shear Life:

The adhesive film test sample was cut rectangular to a width of 13 mm and the adhesive side was placed on a steel plate (blank: material no. 1.4301 according to DIN EN 10088-2 ; Roughness depth approx. 100 nm, then polished and cleaned with acetone; Acetone removed by evaporation for five minutes) glued in such a way that one end of the adhesive film pattern protruded over the (straight running) edge of the steel plate and the longitudinal edges of the adhesive film pattern ran perpendicular to this steel plate edge. The bond area is 20 mm x 13 mm (length x width). After gluing, the back of the adhesive film was rolled back and forth twice with a 2 kg roller. After an opening time of 10 to 15 minutes, a clip (weight 6.5 g) was attached to the protruding end of the adhesive film sample, and a weight with a tensile load of 10 N was again attached to this clip. The steel plate was then hung on a suitable device in such a way that the protruding adhesive film strip was pointing downwards at an angle of 179 ° +/- 1 ° - based on the horizontally aligned steel plate with the adhesive film strip lying on top (i.e. deviating by +/- 2 ° from the vertical). This ensured that the three-layer composite could not peel off the lower edge of the panel. As a result, the adhesive film strip was loaded with a tensile force of 10 N, so that the adhesive film strip began to slide off the steel plate. The measured shear life, the time between loading and falling of the sample, is given in minutes and corresponds to the median of three measurements. The measurement is carried out in a normal climate (23 ° C ± 1 ° C temperature and 50% ± 5% rel. Humidity).

Gel value (degree of crosslinking):

m_n = Gewicht der Probe + Vlies nach der Extraktion [g]
m_v = Gewicht der Probe + Vlies vor der Extraktion [g]
m_T = Gewicht des Trägers der Probe [g]
m_VI = Gewicht des Vlieses [g]
GW = Gelwert [%]The test is carried out with the crosslinked adhesive film sample. Approx. 1 g of the solvent-free adhesive film sample is welded into a fleece bag made of polyethylene (Tyvek fleece). The gel value GW, i.e. the weight fraction of the polymer that is not soluble in ethyl acetate, is determined as follows from the difference between the sample weights adjusted for the weight of the carrier film before the extraction and after the extraction with ethyl acetate: $$\text{GW}=\frac{{\text{m}}_{\text{n}}-{\text{m}}_{\text{VI}}-{\text{m}}_{\text{T}}}{{\text{m}}_{\text{v}}-{\text{m}}_{\text{VI}}-{\text{m}}_{\text{T}}}*100\%$$

m _n = weight of the sample + fleece after extraction [g]
m _v = weight of the sample + fleece before extraction [g]
m _T = weight of the carrier of the sample [g]
m _VI = weight of the fleece [g]
GW = gel value [%]

This value is a direct measure of the degree of crosslinking.

Production of the tested adhesive film samples

Basic recipe for polymerization

A 2 L glass reactor conventional for free radical polymerizations was filled with 16 g of acrylic acid, 304 g of 2-ethylhexyl acrylate, 80 g of stearyl acrylate and 266 g of acetone: special boiling point spirit 60/95 (1: 1). After nitrogen gas had been passed through for 45 minutes with stirring, the reactor was heated to 58 ° C. and 0.2 g of 2,2-azobis (2-methylbutyronitrile), Vazo 67 ™, from DuPont) dissolved in 10 g of acetone was added. The external heating bath was then heated to 75 ° C. and the reaction was carried out constantly at this external temperature. After a reaction time of 1 hour, another 0.2 g of 2,2-azobis (2-methylbutyronitrile), Vazo 67 ™, DuPont) dissolved in 10 g of acetone was added. After a reaction time of 5 hours, 0.6 g of bis (4-tert-butylcyclohexanyl) peroxydicarbonate (Perkadox 16 ™, Akzo Nobel) dissolved in 10 g of acetone was added. After 6 hours, the mixture was diluted with 100 g of special-boiling-point spirit 60/95. After a reaction time of 7 hours, 0.6 g of bis (4-tert-butylcyclohexanyl) peroxydicarbonate (Perkadox 16 ™, Akzo Nobel) dissolved in 10 g of acetone were added. After 10 hours, the mixture was diluted with 150 g of special-boiling-point spirit 60/95. The reaction was terminated after a reaction time of 24 hours and the mixture was cooled to room temperature. The number average molar mass M _n was 80,000 g / mol.

Networking addition

The polyacrylate, produced according to the basic recipe, was mixed with the amount of N, N, N ', N'-tetrakis (2,3-epoxypropyl) -m-xylene-a, a'-diamine (ERISYS® GA-240 , CVC Specialty Chemicals Inc.) as a crosslinker, diluted to a solids content of 33% with special boiling point spirit 60/95 and then coated directly (within a few minutes) from solution onto an etched PET film (thickness 50 μm). After drying for 5 minutes at 60 ° C., the application rate was 35 g / m ² .

The adhesives obtained give the following results in the aforementioned test methods:

The resulting adhesive tape samples from Examples 1 to 6 are each cut into 25 mm wide strips (adhesive tapes) and bonded to a glass fiber scrim (163 g / m ² , twill scrim 2/2, R&G Faserverbundwerkstoffe GmbH). A cutting pad serves as the substrate under the fiberglass scrim. A cutter is then used to cut through the laminate along a ruler along the center of the respective adhesive tape (lengthwise direction).
The adhesive tape was then carefully peeled from the resulting parts of the scrim material in a direction perpendicular to the cut edge. The quality of the cutting process and the dismantling was assessed:

It can be seen from the examples that when crosslinking with 0.5 to 2.5 parts by weight of the selected crosslinker [with an equivalent weight of 100 g / eq] per 100 parts by weight of base polymer, an adhesive is obtained No deformation of the fibers occurs during a cutting process through the fiber material object, slight deformations occur when crosslinking with 2.5 parts by weight of the crosslinker per 100 parts by weight of polymer. If 3 parts by weight of crosslinker per 100 parts by weight of polymer are crosslinked, clear deformations can be seen.

In addition, it turns out that when crosslinking with 0.5 to 3 parts by weight of the crosslinker [equivalent weight of 100 g / eq] per 100 parts by weight of base polymer, an adhesive is obtained with its Use when dismantling the adhesive tape reduces fiber tears, in the range ≥ 1 part by weight of crosslinker to 100 parts by weight, fiber tears can be completely avoided.
The crosslinker is therefore preferably used in the areas as defined in this document.

Example 7 (not according to the invention)

A 2 L glass reactor conventional for radical polymerizations was charged with 12 g of acrylic acid, 174 g of 2-ethylhexyl acrylate, 174 g of butyl acrylate, 40 g of methyl acrylate and 266 g of acetone: special boiling point spirit 60/95 (1: 1). After nitrogen gas had been passed through for 45 minutes with stirring, the reactor was heated to 58 ° C. and 0.2 g of 2,2-azobis (2-methylbutyronitrile), Vazo 67 ™, from DuPont) dissolved in 10 g of acetone was added. The external heating bath was then heated to 75 ° C. and the reaction was carried out constantly at this external temperature. After a reaction time of 1 h, another 0.2 g of Vazo 67 ™ dissolved in 10 g of acetone was added. After a reaction time of 5 hours, 0.6 g of bis (4-tert-butylcyclohexanyl) peroxydicarbonate (Perkadox 16 ™, Akzo Nobel) dissolved in 10 g of acetone were added. After 6 hours, the mixture was diluted with 100 g of special-boiling-point spirit 60/95. After a reaction time of 7 hours, 0.6 g of bis (4-tert-butylcyclohexanyl) peroxydicarbonate (Perkadox 16 ™, Akzo Nobel) dissolved in 10 g of acetone were added. After 10 hours, the mixture was diluted with 150 g of special-boiling-point spirit 60/95. The reaction was terminated after a reaction time of 24 hours and the mixture was cooled to room temperature. The polyacrylate, with 1.0 part by weight of N, N, N ', N'-tetrakis (2,3-epoxypropyl) -m-xylene-a, a'-diamine crosslinker (ERISYS® GA-240, CVC Specialty Chemicals Inc.) mixed to 100 parts by weight of polymer, diluted to a solids content of 33% with special boiling point spirit 60/95 and then coated from solution onto an etched PET film. After drying for 5 minutes at 60 ° C., the application rate was 35 g / m ² . The gel value was 96%.

Example 8 (not according to the invention)

A 2 L glass reactor conventional for radical polymerizations was charged with 4 g of acrylic acid, 198 g of 2-ethylhexyl acrylate, 198 g of butyl acrylate and 266 g of acetone: special boiling point spirit 60/95 (1: 1). After nitrogen gas had been passed through for 45 minutes with stirring, the reactor was heated to 58 ° C. and 0.2 g of 2,2-azobis (2-methylbutyronitrile), Vazo 67 ™, from DuPont) dissolved in 10 g of acetone was added. The external heating bath was then heated to 75 ° C. and the reaction was carried out constantly at this external temperature. After a reaction time of 1 h, another 0.2 g of Vazo 67 ™ dissolved in 10 g of acetone was added. After a reaction time of 5 hours, 0.6 g of bis (4-tert-butylcyclohexanyl) peroxydicarbonate (Perkadox 16 ™, Akzo Nobel) dissolved in 10 g of acetone were added. After 6 hours, the mixture was diluted with 100 g of special-boiling-point spirit 60/95. After a reaction time of 7 hours, 0.6 g of bis (4-tert-butylcyclohexanyl) peroxydicarbonate (Perkadox 16 ™, Akzo Nobel) dissolved in 10 g of acetone were added. After 10 hours, the mixture was diluted with 150 g of special-boiling-point spirit 60/95. The reaction was terminated after a reaction time of 24 hours and the mixture was cooled to room temperature. The polyacrylate, with 1.0 part by weight of N, N, N ', N'-tetrakis (2,3-epoxypropyl) -m-xylene-a, a'-diamine crosslinker (ERISYS® GA-240, CVC Specialty Chemicals Inc.) mixed to 100 parts by weight of polymer, diluted to a solids content of 33% with special boiling point spirit 60/95 and then coated from solution onto an etched PET film. After drying for 5 minutes at 60 ° C., the application rate was 35 g / m ² . The gel value was 97%.

The bond strength to glass and its behavior over time were investigated using the methods given above.

25 mm wide strips of the resulting adhesive tape samples from Examples 7 and 8 are glued to a glass fiber scrim (163 g / m ² twill scrim 2/2, R&G Faserverbundwerkstoffe GmbH), and a cutter knife is used to cut through the laminate (in a corresponding manner to the Examples 1 to 6). The adhesive tape was then peeled off from the scrim material (again in accordance with the procedure in Examples 1 to 6). The quality of the cutting process and the dismantling was assessed:

It can be seen from reference examples 7 and 8 that the basic composition of the monomer mixture is also important. If the monomer composition is different - even if the crosslinker used according to the invention is used in amounts according to the invention - there are no positive results. In both examples - with a basically similar composition - component (c) is absent, and both examples do not lead to the success of the invention.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• WO 2017/042221 A [0061]

Non-patent literature cited

• DIN EN ISO 3001: 1999-11 [0014]
• DIN 53765: 1994-03 [0056]
• DIN EN 10088-2 [0061, 0062]

Claims (17)

Method for assembling fiber material objects, wherein the fiber material object is stabilized by an adhesive film in at least one of the assembling steps, characterized in that the adhesive film comprises a layer of an adhesive for bonding on the fiber material, which is obtainable by I. radical polymerization of the following monomer composition (a ) 52 to 88% by weight of one or more acrylic acid esters with linear and / or branched alkyl radicals with 4 to 10 carbon atoms, (b) 2 to 8% by weight of one or more monomers selected from the list of acrylic acid, methacrylic acid, itaconic acid, (c) 10 to 40% by weight of one or more acrylic acid esters with a linear alkyl radical having 12 to 20 carbon atoms, the percentages by weight being based on the monomer composition of components (a), (b) and (c), II. subsequent Crosslinking of the polymer obtained in the presence of at least one at least two crosslinking-active groups en having crosslinking reagent with an equivalent weight EW, based on the crosslinking active groups, in the range from 80 to 220 g / eq, which is based in an initial amount of (0.005 * | EW |) to (0.025 * | EW |) parts by weight to 100 parts by weight of the monomer composition, is present in the polymer, up to a degree of crosslinking of at least 90%. Use of an adhesive film for stabilization in at least one of the steps in the assembly of fiber material objects, characterized in that the adhesive film comprises a layer of an adhesive for bonding to the fiber material, which is obtainable by I. radical polymerization of the following monomer composition (a) 52 to 88 % By weight of one or more acrylic acid esters with linear and / or branched alkyl radicals with 4 to 10 carbon atoms, (b) 2 to 8% by weight of one or more monomers selected from the list of acrylic acid, methacrylic acid, itaconic acid, (c) 10 up to 40% by weight of one or more acrylic acid esters with a linear alkyl radical having 12 to 20 carbon atoms, the percentages by weight being based on the monomer composition of components (a), (b) and (c), II. subsequent crosslinking of the polymer obtained in the presence of at least one crosslinking reagent having at least two crosslinking-active groups with an eq equivalent weight EW, based on the active crosslinking groups, in the range from 80 to 220 g / eq, which is in an initial amount of (0.005 * | EW |) to (0.025 * | EW |) parts by weight, based on 100 wt. Parts of the monomer composition present in the polymer up to a degree of crosslinking of at least 90%. Procedure according to Claim 1 or use after Claim 2 , characterized in that the percentages by weight of components (a), (b) and (c) add up to 100% by weight, ie the monomer composition does not comprise any further comonomers. Method or use according to one of the preceding claims, characterized in that the initial amount of the at least one crosslinking reagent (0.01 * | EW |) to (0.02 * | EW |) parts by weight, based on 100 wt. Parts of the monomer composition. Method or use according to one of the preceding claims, characterized in that one or more representatives is / are selected from the following list as the crosslinking reagent: N, N, N ', N'-tetrakis (2,3-epoxypropyl) -m- xylen-a, a'-diamine (CAS 63738-22-7), • N, N, N ', N'-tetrakis (2,3-epoxypropyl) cyclohexane-1,3-dimethylamine (CAS 65992-66-7 ), • Poly) bisphenol A-co-epichlorohydrin (CAS 25068-38-6), • 4,4 '- (1-methylethylidene) bis-cyclohexanol, polymer with 2- (chloromethyl) oxirane (CAS 30583-72-3 ). Method or use according to one of the preceding claims, characterized in that the polymer obtained in step I and comprising at least one crosslinking reagent is applied as a layer to a permanent or temporary support, and the predominant part of the crosslinking in step II takes place after this layer has been formed . Method or use according to one of the preceding claims, characterized in that the manufacturing step in which the fiber material is stabilized by the adhesive film is or includes cutting the fiber material, in particular cutting with a blade, a cutting robot and / or by means of a water jet. Method or use according to one of the preceding claims, characterized in that the stabilization is temporary in that the adhesive film is applied before the manufacturing step in which the fiber material is stabilized by the adhesive film and is removed again after this manufacturing step. Method or use according to one of the preceding claims, characterized in that the fiber material object is a scrim, woven, knitted fabric, fleece, textile, roving (bundles, strands or multifilament yarns made of filaments arranged essentially in parallel), a fiber mat or wood or a multitude of the aforementioned objects is formed. Method or use according to one of the preceding claims, characterized in that the fiber material object is wood, bast, flax, hemp, silk, wool, cotton, jute, Kanaf, ramie, sisal, hair, silicate fibers, polylactide fibers, polyamide fibers, casein fibers, acetate fibers, glass fibers, Carbon fibers, fibers made from carbonaceous materials (carbon fibers, carbon fibers, carbon fibers), ceramic fibers, liquid crystal polymer fibers (aramid fibers such as Kevlar), boron fibers, basalt fibers, steel fibers and / or nylon fibers. Adhesive film comprising at least one layer of an adhesive which is obtainable by I. radical polymerization of the following monomer composition (a) 52 to 88% by weight of one or more acrylic acid esters with linear and / or branched alkyl radicals with 4 to 10 carbon atoms, (b) 2 to 8% by weight of one or more monomers selected from the list of acrylic acid, methacrylic acid, itaconic acid, (c) 10 to 40% by weight of one or more acrylic acid esters with a linear alkyl radical with 12 to 20 carbon atoms, the percentages by weight being based on the monomer composition of components (a), (b) and (c), II. Subsequent crosslinking of the polymer obtained in the presence of at least one crosslinking reagent containing at least two crosslinking-active groups and having an equivalent weight EW, based on the crosslinking-active groups, in the range from 80 to 220 g / eq, in an initial amount of (0.005 * | EW |) to (0.025 * | EW |) parts by weight, in particular from (0.01 * | EW |) to (0.02 * | EW |) parts by weight , based on 100 parts by weight of the monomer composition, is present in the polymer, up to a degree of crosslinking of at least 90%. Adhesive film after Claim 10 , characterized in that an adhesive layer as in Claim 10 defined on at least one side of a transparent or translucent polyethylene terephthalate carrier layer which is etched on at least the adhesive side. Adhesive film after Claim 11 , characterized in that an adhesive layer as in Claim 10 defined on both sides of a transparent, double-sided etched polyethylene terephthalate carrier layer is applied. Adhesive film after one of the Claims 10 to 12 , characterized in that the adhesive film is silicone-free, carbamate-free and free of other release agents. Adhesive tape made from an elongated strip of adhesive film following one of the Claims 10 to 13 . Tape after Claim 15 , characterized in that an adhesive-free area is provided on the surface of the carrier film equipped with adhesive on at least one, preferably on both, longitudinal edges. Roll of adhesive tape, represented by an adhesive tape wound into an Archimedean spiral after one of the Claims 14 or 15th , characterized in that no separating material is provided between the individual windings.