EP3452558A1

EP3452558A1 - Rubber-based self-adhesive compound

Info

Publication number: EP3452558A1
Application number: EP17718053.6A
Authority: EP
Inventors: Tobias von Wedel-Parlow; Axel Burmeister; Kai Ellringmann; Julia SCHWARZBACH
Original assignee: Tesa SE
Current assignee: Tesa SE
Priority date: 2016-05-06
Filing date: 2017-04-13
Publication date: 2019-03-13
Also published as: WO2017190935A1; US20190106604A1; KR20190005921A; DE102016207822A1; JP2019516000A; CN109072026A

Abstract

The invention relates to a self-adhesive compound consisting of a mixture containing: rubber, particularly natural rubber; at least one adhesive resin where said adhesive resins are present at an amount of 40 to 130 phr; and expanded polymer microbeads.

Description

tesa Societas Europaea

Norderstedt

description

Self-adhesive based on rubber

The invention relates to the composition of a (natural) rubber self-adhesive composition and to the use thereof.

Pressure-sensitive adhesives, also referred to as self-adhesive compositions, are known to those skilled in the art and are very widely used. As pressure-sensitive adhesives are simplified called adhesives that allow even under relatively low pressure a permanent connection with the primer and can be replaced after use substantially residue-free from the primer again.

Adhesive tapes, which are equipped with pressure-sensitive adhesives, so-called pressure-sensitive adhesive tapes, are today used in a variety of industrial and private sectors. Usually pressure-sensitive adhesive tapes consist of a carrier material, often a carrier film, which is equipped on one or both sides with a pressure-sensitive adhesive. There are also pressure-sensitive adhesive tapes that consist exclusively of a pressure-sensitive adhesive layer and no carrier film, the so-called transfer tapes. The composition of the pressure-sensitive adhesive tapes can be very different and depends on the respective requirements of the different applications. The carriers are usually made of plastic films such as polypropylene, polyethylene, polyester or paper, woven or nonwoven fabric.

The self- or pressure-sensitive adhesives usually consist of acrylate copolymers, silicones, natural rubber, synthetic rubber, styrene block copolymers or polyurethanes.

Natural rubber is an elastic polymer based on plant products, especially latex (latex). Natural rubber is processed as an essential raw material into natural rubber adhesives. For setting application-specific properties, pressure-sensitive adhesives can be modified by admixing tackifier resins, plasticizers, aging inhibitors, processing aids, fillers, dyes, optical brighteners and / or stabilizers.

Fillers are used, for example, to increase the cohesion of a pressure-sensitive adhesive. Often, a combination of filler / filler interactions and filler / polymer interactions results in the desired reinforcement of the polymer matrix.

Fillers are also added to increase the weight or volume of paper, plastics, adhesives, paints and other products. The filler addition often improves the technical usefulness of the products and has an influence on their quality, for example strength, hardness, etc. The natural, inorganic and organic fillers such as calcium carbonate, kaolin, talc, dolomite and the like are produced mechanically.

Even with rubber and synthetic elastomers can be improved by suitable fillers, the quality, such as hardness, strength, elasticity and elongation. Frequently used fillers are carbonates, in particular calcium carbonate, but also silicates (talc, clay, mica), silica, calcium and barium sulfate, aluminum hydroxide, glass fibers and spheres, and carbon blacks.

It is possible to distinguish inorganic and organic fillers according to their density. Thus, the inorganic fillers often used in plastics and adhesives, such as chalk, titanium dioxide, calcium and barium sulfate increase the density of the composite, since they themselves have a density which is higher than that of the polymer. For the same layer thickness, the basis weight is then higher.

There are also fillers that can reduce the overall density of the composite. These include hollow microspheres, very voluminous lightweight fillers. The balls are filled with gases such as air, nitrogen or carbon dioxide, the spherical shells are made of glass, in some products also from a thermoplastic.

Foamed PSA systems, especially foamed with microballoons, are also described in the prior art. In principle, polymer foams can be produced in two ways. On the one hand by the action of a propellant gas, whether it is added as such or resulting from a chemical reaction, on the other hand by the incorporation of hollow spheres in the material matrix. Foams made in the latter way are called syntactic foams.

In a syntactic foam, hollow spheres such as glass spheres or ceramic hollow spheres (microspheres) or microballoons are incorporated in a polymer matrix. As a result, the voids are separated from one another in a syntactic foam and the substances (gas, air) located in the cavities are separated from the surrounding matrix by a membrane.

With micro hollow balls foamed masses are characterized by a defined cell structure with a uniform size distribution of the foam cells. With hollow microspheres, closed-cell foams are obtained without cavities, which are distinguished, among other things by a better sealing effect against dust and liquid media compared to open-cell variants. In addition, chemically or physically foamed materials are more prone to irreversible collapse under pressure and temperature, and often exhibit lower cohesive strength.

Particularly advantageous properties can be achieved if expandable microspheres (also referred to as "microballoons") are used as microspheres for foaming. By virtue of their flexible, thermoplastic polymer shell, such foams have a higher adaptability than those which are compatible with non-expandable, non-polymeric hollow microspheres (for example They are more suitable for compensating for manufacturing tolerances, which are the rule for injection molded parts, for example, and because of their foam character they can also better compensate for thermal stresses For example, even if the foam has a lower density than the matrix, it is possible to produce foams having a higher cohesive strength than the polymer matrix alone foam properties such as adaptability rough substrates with a high cohesive strength for self-adhesive foams can be combined.

From DE 10 2013 207 467 A1, a polymer foam with high bond strength and improved compression hardness behavior is known. This is achieved by cavities formed by the polymer foam of microballoons and 2 to 20% by volume, based on the total volume of the polymer foam, of cavities enclosed by the polymer foam matrix. The subject of the application is also a process for producing a polymer foam.

Furthermore, pressure-sensitive adhesives containing expanded microballoons are known from DE 10 2008 004 388 A1. It is essential to the invention that the adhesive force of the adhesive containing the expanded microballoons is particularly preferred by at most 30%, preferably at most 20%, in comparison to the bond strength of a compositionally weighted and formulation-identical adhesive which is defoamed due to the destruction of the cavities formed by the expanded microballoons 10% is reduced

Floor coverings, for example carpets, PVC floor coverings or the like, are usually fixed with solvent-containing, liquid contact adhesives in areas which are exposed to particular tread stresses. For example, this applies to the area of the aisles in public transport such as airplanes, buses or trains, wherein in a corresponding flooring installation both the substrate is coated with corresponding contact adhesives and the back of the flooring itself and wherein when bringing these two adhesive coated parts achieved a firm connection becomes.

This known procedure is laborious on the one hand and on the other hand, the corresponding liquid contact adhesives usually contain solvents, which should be avoided, as these may be harmful to one hand and on the other hand may even be explosive. Especially in airplanes, therefore, the use of solvent-containing adhesives is viewed as very critical.

Furthermore, there is the possibility of flooring, especially carpets, with double-sided carpet laying tapes or double-sided self-adhesive tapes To bond floors. Typically, these tapes for laying a floor covering on a floor of a substrate with a plastic film, which is equipped on both sides with a pressure-sensitive adhesive coating.

A Bodenbelagsverklebung with such an adhesive tape has the advantage that immediately an adhesive force is established. In the long term, however, under certain loading conditions, there may be a possibility that the adhesive force to the flooring may not be as high as in the case of the liquid contact adhesives described above because the adhesive coating of such adhesive tape is different than the contact adhesives described above - Can not flow into the carpet back, so as to permanently enter into a particularly strong connection with all marketable backs of corresponding floor coverings. Thus, at particularly loaded treads, which may be exposed to increased shear and tensile load and increased friction, a correspondingly paved flooring replace over time again or bulge at appropriate points. Since corresponding self-adhesive films adhere particularly well to smooth backs of floor coverings, the described problem can be reinforced in carpet backing on fabric or textile basis, which make up the vast majority. Furthermore, there are special requirements for all materials used, especially in aircraft construction. These must in principle have certain properties in order to be used or allowed.

First, they must be as flammable as possible or generally have good fire protection.

Adhesive tapes, which are used for the bonding of floor coverings in the aisles of aircraft, in addition, the requirement is made that they are as light as possible, to a low, but still not negligible weight saving in order to reduce fuel costs and increase the payload over alternative solutions entail.

Then the floor coverings in aircraft aisles (or similar vehicles) have to be regularly replaced due to the considerable loads they are subjected to. In this case, it is necessary that the adhesive tapes used for bonding residue can be removed in particular from the ground so that (time) consuming cleaning work can be avoided.

On the other hand, the adhesive tapes should permanently provide a secure anchoring of a floor covering on a floor, even in particularly stressed areas, for example in the aisles of an aircraft.

During the application of the floor covering on the floor, therefore, a high initial bond strength is of great importance. This applies in particular to the cases in which the floor covering is in the form of a sheet-like material which is unrolled shortly before or during the application. In these cases, it may be due to the Vorkrümmung of the material in particular at the Verklebungsrändern to set up the flooring. This leads to an increased load on the bond area. For the residue-free recyclability, it is still crucial that the initial bond strengths do not take over the time of use.

The object of the invention is to demonstrate a possibility with which self-adhesive compositions based on (natural) rubber are available for technical applications, in particular for the bonding of temporary substrates such as textile floor coverings on permanent substrates such as floors, for example in an aircraft which has a lower density than have conventional adhesives, which show a sufficient bond strength, which are as far as possible redetachable and which show an improvement in flame resistance.

This object is achieved by a self-adhesive composition, as laid down in the main claim. The subject of the dependent claims are advantageous developments of the subject invention. Furthermore, the invention comprises the use of this self-adhesive composition.

Accordingly, the invention relates to a self-adhesive composition consisting of a mixture containing rubber, in particular natural rubber and tackifier resins, wherein the proportion of tackifier resins is 70 to 130 phr, preferably 80 to 120 phr, and expanded polymeric microspheres.

The information given below in phr means parts by weight of the relevant component based on 100 parts by weight of all elastomeric or Rubber polymer components of the PSA (solid / solid), ie (natural rubber) component or other elastomers and thus, for example, without consideration of the (polymeric) adhesive resins.

The statement wt .-% is always below based on the composition of the total PSA.

Self-adhesive compositions, also referred to as pressure-sensitive adhesives, are in the sense of the invention in particular those polymeric compositions which are permanently tacky and tacky at the application temperature (unless otherwise defined, at room temperature), optionally by suitable addition with further components such as adhesive resins, and at a plurality of Adhere surfaces to contact, in particular immediately adhere (a so-called "tack".) They are able, even at the application temperature without activation by solvents or by heat - but usually by the influence of a more or less high pressure - to adequately wet a substrate to be bonded, so that adequate interactions can form between the compound and the substrate for adhesion, for which the influencing parameters include pressure and contact time Among other things, the PSAs are based in particular on their viscoelastic properties. Thus, for example, weakly or strongly adhering adhesives can be produced; furthermore, those which can be glued only once and permanently, so that the bond can not be released without destroying the adhesive and / or the substrates, or those which are easy to redetach and, if necessary, can be glued multiple times.

Pressure-sensitive adhesives can in principle be produced on the basis of polymers of different chemical nature. The pressure-sensitive adhesive properties are influenced inter alia by the nature and the proportions of the monomers used in the polymerization of the polymers on which the PSA is based, their average molecular weight and molecular weight distribution, and by the nature and amount of the PSA additives such as tackifier resins, plasticizers and the like.

To achieve the viscoelastic properties, the monomers on which the PSA-based polymers are based, as well as the optional further components of the PSA, are chosen such that the PSA has a glass transition temperature (according to DIN 53765) below the application temperature (ie usually below room temperature ) exhibit. By means of suitable cohesion-increasing measures, such as, for example, crosslinking reactions (formation of bridge-forming linkages between the macromolecules), the temperature range in which a polymer composition has pressure-sensitive adhesive properties can be increased and / or shifted. The scope of the PSAs can thus be optimized by adjusting the flowability and cohesion of the mass.

A PSA is permanently tacky at room temperature, so it has a sufficiently low viscosity and high tack, so that it wets the surface of the respective Klebegrunds already at low pressure. The adhesiveness of the adhesive is based on its adhesive properties and the removability on their cohesive properties.

The PSAs according to the invention are removable due to their composition.

According to the invention, the adhesive contains rubber, in particular natural rubber. Furthermore, the adhesive of the invention synthetic rubbers such as synthetic rubber or the synthetic rubbers from the group of random copolymerized styrene-butadiene rubbers (SBR), the butadiene rubbers (BR), the synthetic polyisoprenes (IR), the butyl rubbers (II FR ), the halogenated butyl rubbers (XI IR), the polyarcylates, the acrylate rubbers (ACM), the polybutadienes (PB), the ethylene-vinyl acetate copolymers (EVA) and the polyurethanes and / or their blends individually or in any mixture containing natural rubber.

The particularly preferred natural rubber or natural rubbers can in principle be selected from all available qualities such as Crepe, RSS, ADS, TSR or CV types, depending on the required level of purity and viscosity. Preferably, to improve the processability, thermoplastic elastomers, such as synthetic rubbers, may be added to the natural rubber at a level of up to 5% by weight.

Representative may be mentioned at this point especially the most compatible styrene-isoprene-styrene (SIS) - and styrene-butadiene-styrene (SBS) types. Preferably, the base polymer of the PSA consists of natural rubber, more preferably, in addition to natural rubber, no further elastomeric polymer is present in the PSA.

In this case, the pressure-sensitive adhesive is a composition of natural rubber, one or more adhesive resin (s), preferably anti-aging agent (s) and expanded polymeric microspheres, which is a preferred embodiment. In addition, in addition, the later explained fillers and / or dyes may optionally be present in small amounts. By the term "tackifier resin", the skilled person understands a resin-based substance which increases the tackiness.

In particular, hydrogenated and unhydrogenated hydrocarbon resins and polyterpene resins can be used as adhesive resins in the case of the self-adhesive composition as main component. Among others, hydrogenated polymers of dicyclopentadiene (for example Escorez 5300 series, Exxon Chemicals), hydrogenated polymers of preferably Cs and Cg aromatics (for example Regalite and Regalrez series, Eastman Inc. or Arkon P series, Arakawa) are particularly suitable. These can flow by hydrogenation of polymers of pure aromatic streams or based by hydrogenation of polymers based on mixtures of different aromatics. Also suitable are partially hydrogenated polymers of Cs and Cg aromatics (for example Regalite and Regalrez series, Eastman Inc. or Arkon M, Arakawa), hydrogenated polyterpene resins (for example Clearon M, Yasuhara), hydrogenated Cs / Cg polymers (for example ECR-373; Exxon Chemicals), aromatically modified, selectively hydrogenated dicyclopentadiene derivatives (e.g., Escorez 5600 series; Exxon Chemicals). The aforementioned adhesive resins can be used both alone and in admixture.

Other non-hydrogenated hydrocarbon resins, non-hydrogenated analogs of the hydrogenated resins described above may also be used.

Furthermore, rosin-based resins (for example, foral, foralyn) can be used.

The rosin resins mentioned above include, for example, natural rosin, polymerized rosin, partially hydrogenated rosin, fully hydrogenated rosin, esterified products of these rosins (such as glycerol esters, Pentaerythritol esters, ethylene glycol esters and methyl esters) and rosin derivatives (such as disproportionating rosin, fumaric acid-modified rosin and lime-modified rosin). Adhesive resins preferred according to the invention are (partially) hydrogenated hydrocarbon resins based on Cs, C5 / C9 or C9 and also polyterpene resins based on α-pinene and / or β-pinene and / or δ-limonene and terpene-phenol resins.

Very particular preference is given to terpene-phenolic resins, in particular only terpene-phenolic resins, without the use of other types of resin.

To stabilize the PSA, it is customary to add primary antioxidants, for example sterically hindered phenols, secondary antioxidants, for example phosphites or thioethers and / or C radical scavengers. The natural rubber-based pressure-sensitive adhesive may contain additives such as fillers, dyes or anti-aging agents (antiozonants, light stabilizers, etc.) for adjusting optical and adhesive properties.

As additives to the adhesive are typically used:

· Primary antioxidants such as sterically hindered phenols

• secondary antioxidants such as phosphites or thioethers

• Sunscreens such as UV absorbers or hindered amines

The fillers can be reinforcing or non-reinforcing. Above all, mention should be made here of silicas (spherical, needle-shaped or irregular, such as pyrogenic silicas), calcium carbonates, zinc oxides, titanium dioxides, aluminum oxides or aluminum oxide hydroxides.

The concentration of the additives which influence the optical and adhesive properties is preferably up to 20% by weight, more preferably up to 15% by weight. The listed substances are not mandatory, the adhesive also works without these are added individually or in any combination, ie without fillers and / or dyes and / or anti-aging agents. The foam is obtained by expanded polymeric microspheres.

Microspheres, also referred to as "microballoons", are understood as meaning elastic hollow microspheres which are expandable in their ground state and which have a thermoplastic polymer shell These spheres are filled with low-boiling liquids or liquefied gas The polyacrylonitrile, PVDC, PVC or polyacrylates, in particular, are used as the shell material Suitable low-boiling liquids are, in particular, hydrocarbons of the lower alkanes, for example isobutane or isopentane, which are enclosed as liquefied gas under pressure in the polymer shell.

By acting on the microballoons, in particular by a heat, softens the outer polymer shell. At the same time, the liquid propellant gas in the casing changes into its gaseous state. The microballoons expand irreversibly and expand in three dimensions. The expansion is completed when the internal and external pressures equalize. As the polymeric shell is preserved, this results in a closed-cell foam.

There are a variety of types of microballoons available commercially, which differ essentially by their size (6 to 45 μηη diameter in the unexpanded state) and their expansion required for starting temperatures (75 to 220 ° C). An example of commercially available microballoons are the Expancel DU ^® types (DU = dry unexpanded) from Akzo Nobel.

Unexpanded microballoon types are also available as an aqueous dispersion having a solids or microballon content of about 40 to 45 wt%, and also as polymer bound microballoons (masterbatches), for example, in ethylvinyl acetate having a microballoon concentration of about 65 wt%. Both the microballoon dispersions and the masterbatches, like the DU types, are suitable for producing a foamed PSA according to the invention. Foaming can also be produced with so-called pre-expanded microballoons. In this group, the expansion takes place even before the mixing into the polymer matrix. Pre-expanded microballoons are commercially available, for example under the designation Dualite ^® or with the type designation Expancel xxx DE yy (Dry Expanded) from Akzo Nobel, "xxx" represents the composition of the Mikroballonsabmischung. "Yy" is the size of the microballoons in expanded Status.

Preferably, the microballoons are selected such that the ratio of the density of the polymer matrix to the density of the (not or only slightly pre-expanded) microballoons to be incorporated into the polymer matrix is between 1 and 1: 6, ie:

Density of the polymer matrix

Density of the incorporated microballoons is. Only after or immediately after incorporation does the expansion take place. In the case of solvent-containing compositions, the microballoons are preferably expanded only after incorporation, coating, drying (solvent evaporation).

DU types are therefore preferably used according to the invention. According to the invention, at least 90% of all cavities formed by microballoons in the pressure-sensitive adhesive preferably have a maximum diameter of 10 to 200 μm, more preferably 15 to 150 μm. The maximum diameter is defined as the maximum extent of a microballoon in any spatial direction, and the diameters are determined using a cryobreakedge in a scanning electron microscope (SEM) at a magnification of 500. The diameter of each individual microballoon is determined graphically.

The microballoons can be fed to the formulation as a batch, paste or as a cut or blended powder. Furthermore, they may be suspended in solvent.

The proportion of the microballoons in the pressure-sensitive adhesive is according to a preferred embodiment of the invention between greater than 0 wt .-% and 30 wt .-%, in particular between 1, 5 wt .-% and 10 wt .-%, each based on the total composition of the PSA.

The data refer to unexpanded microballoons. A pressure-sensitive adhesive containing expanded polymeric microspheres may also contain partially incomplete or non-expanded microspheres. In the process, rather, a distribution of different expansion states occurs.

In the context of the invention, expanded microballoons include fully or partially expanded microballoons. Unexpanded microballoons may additionally be present.

An expandable hollow microspheres containing polymer composition may additionally contain non-expandable hollow microspheres. The decisive factor is that almost all caverns containing gas are closed by a permanently impermeable membrane, regardless of whether this membrane consists of an elastic and thermoplastically expansible polymer mixture or of elastic and / or - in the range of possible temperatures in plastics processing - non- thermoplastic glass.

Also suitable for the PSA are - regardless of other additives - solid polymer beads such as PMMA beads, glass bubbles, glass beads, phenolic resin beads, ceramic hollow beads, ceramic solid beads and / or full carbon carbon beads ("Carbon Micro Balloons"), preferably the components mentioned are not in the The absolute density of the foamed PSA is preferably 350 to 900 kg / m ³ , more preferably 450 to 700 kg / m ³ , in particular 500 to 600 kg / m ³ .

The relative density describes the ratio of the density of the foamed PSA to the density of the formulation-identical, unfoamed PSA. The specific gravity of the pressure-sensitive adhesive is preferably 0.35 to 0.99, more preferably 0.45 to 0.97, especially 0.50 to 0.90.

The foamed PSA is a syntactic foam. In a syntactic foam, the cavities are separated from each other and the substances in the cavities (gas, air) through a membrane of the separated surrounding matrix. As a result, the material is much stronger than conventional foams with unreinforced gas inclusions.

The PSA preferably consists of the following constituents:

Containing pressure-sensitive adhesive

a) 30 wt .-% to 59.9 wt .-%, preferably 45 wt .-% to 53.5 wt .-% natural rubber

b) 40 wt .-% to 69.9 wt .-%, preferably 45 wt .-% to 55 wt .-% terpene phenolic resin

c) 0.1 wt .-% to 30 wt .-%, in particular between 1, 5 wt .-% and 10 wt .-% expanded polymeric microspheres (based on unexpanded microballoons) and

With particular preference, the PSA consists of the following constituents:

Containing pressure-sensitive adhesive

d) 30% by weight to 59.9% by weight, preferably 45% by weight to 53.5% by weight

natural rubber

e) 40 wt .-% to 69.9 wt .-%, preferably 45 wt .-% to 55 wt .-% of at least one adhesive resin, in particular terpene phenolic resin

f) 0.1 wt .-% to 30 wt .-%, in particular between 1, 5 wt .-% and 10 wt .-% expanded polymeric microspheres (based on unexpanded microballoons) and g) 0 wt .-% to 20 Wt .-%, preferably up to 5 to 10 wt .-% of other additives

More preferably, the adhesive composition is as follows:

Containing pressure-sensitive adhesive

a) 45 wt .-% to 53.5 wt .-% natural rubber

b) 45% to 55% by weight terpene phenolic resin

c) 1, 5 wt .-% and 10 wt .-% expanded polymeric microspheres (based on unexpanded microballoons) and

d) 0 wt .-% of other additives

Surprisingly and in no way foreseeable by the person skilled in the art, a pressure-sensitive adhesive of the invention, which is foamed with microballoons, passes the flame test, as the examples show. This is very surprising insofar as readily flammable gases such as isobutane and / or pentane are used as blowing agents in the microballoons. That is, a foamed pressure-sensitive adhesive of the present invention shows better fire behavior than a non-foamed of the same composition and layer thickness, although in the foamed a much larger surface is available and although combustible gases such as isobutane and / or pentane are introduced into the adhesive.

Even if the PSA according to the invention already passes the flame test without the addition of flame retardants, it may be necessary for certain applications to further increase the flame resistance by adding additional flame retardants. Many different flame retardants are known to the person skilled in the art from the prior art. These differ both in their mechanism of action and in their chemical structure. For use in the pressure-sensitive adhesive of the invention, good compatibility with the polymer matrix as well as the influence on the density of the overall structure are decisive. In addition, the addition of flame retardant, as well as other fillers, adversely affect the bond strength. For use in the pressure-sensitive adhesive of the invention is a variety of flame retardants. Flame retardants based on organic phosphorus compounds (for example DOPO or a reaction product of DOPO and another compound in which the H of the P-H bond is substituted by an organic radical) have proved to be particularly suitable. In any case, no halogenated flame retardants are added to the pressure-sensitive adhesive of the invention. Due to the good flame retardancy properties of the PSAs of the invention, their proportion can be significantly reduced with the addition of flame retardants compared to previous PSAs. Preference is given to using from 0% by weight to 20% by weight, preferably from 5 to 10% by weight, of flame retardant, with no further additives being used at the same time.

As already described, it is of great importance for the use of the PSA according to the invention for bonding temporary substrates on permanent substrates that no residues remain on the permanent substrate when the PSA is removed.

Advantageously, the cohesion of the mass is set sufficiently high for this purpose. Among other things, this can also be achieved by crosslinking the PSA or parts of the PSA, for example the base polymer. For this is one Variety of chemical or physical methods known. For unsaturated elastomers, in particular the particularly suitable natural rubber, electron beams can be used in addition to sulfur or resole crosslinking. These provide a radical formation and subsequent crosslinking of the isoprene units. Such a downstream crosslinking is particularly important in the compounding of the PSA according to the invention in an extruder. The shearing forces occurring during the extrusion can lead to a reduction in the molecular weight of the natural rubber polymer chains, which is accompanied by a lowering of the cohesion. The person skilled in this process is known as mastication. Accordingly, a networking and thus a reconstruction of the polymer network is of great importance. In this respect, the PSAs according to the invention are preferably crosslinked and, in the case of isoprene-based rubbers, preferably crosslinked with electron beams. Thus, it is prevented or at least reduced that the mass split cohesively during redetachment and thus leaves a high proportion of residues. Irradiation with electrons can bring about an improvement. In this case, the dose must be selected in particular so that the bond strength is not lowered too far by the crosslinking, the skilled person being aware of the dose to be selected.

Preferably, the pressure-sensitive adhesive is used in adhesive tapes.

Adhesive tapes in the context of the invention are understood to mean all flat or band-shaped carrier structures coated on one or both sides with the adhesive of the invention, ie labels, sections, diecuts (punched flat carrier structures coated with adhesive), two-dimensionally extended structures (for example films ) and the like, also multi-layer arrangements.

Furthermore, the term "adhesive tape" also includes so-called "transfer tapes", that is, an adhesive tape without a carrier. In the case of a transfer adhesive tape, the adhesive is applied before application between flexible liners, which are provided with a release layer and / or have anti-adhesive properties. For application, a liner is first removed, the adhesive is applied and then the second liner is removed.

A liner (release paper, release film) is not part of an adhesive tape or label, but only an aid for their production, storage or for further processing by punching. In addition, unlike a tape carrier, a liner is not firmly bonded to an adhesive layer.

In addition to the abovementioned transfer adhesive tapes, double-sided adhesive tapes are preferred in which the support, in particular the carrier film, is provided on both sides with the PSA according to the invention.

The tape can be provided in fixed lengths such as by the meter or as an endless product on rolls (Archimedean spiral).

The application (coating thickness) of the adhesive (be it on a liner, be it in the sum of the two adhesive layers on a carrier film) is preferably between 10 and 300 g / m ² , more preferably between 15 and 250 g / m ² , very particular preferably between 15 and 200 g / m ² .

Furthermore, a double-sided self-adhesive tape preferably has an asymmetrical structure in which the two sides are coated with a different application of the pressure-sensitive adhesive or of the PSAs. In this case, the mass application of one side is between 10 and 100 g / m ² and the application of the other side is between 50 g / m ² and 300 g / m ² .

As support materials for the pressure-sensitive adhesive tape, the usual and familiar to those skilled carrier materials such as paper, fabric, non-woven or films of, for example, polyester such as polyethylene terephthalate (PET), polyethylene, polypropylene, stretched polypropylene, polyvinyl chloride used. Particular preference is given to support materials which are not or only very weakly extensible, such as BOPP and in particular PET.

As materials for the film polyester, in particular polyethylene terephthalate, polyamide, polyimide or mono- or biaxially stretched polypropylene are used. Also possible is the use of multilayer laminates or coextrudates.

Preferably, the film is single-layered. In order to achieve very good results for the roughening, it is recommended to use as reagent for etching the film trichloroacetic acid (C C -COOH) or trichloroacetic acid in combination with inert crystalline compounds, preferably silicon compounds, particularly preferably [SiO 2] x.

The purpose of the inert crystalline compounds is to be incorporated into the surface of the PET film to enhance roughness and surface energy.

The thickness of the film according to a preferred embodiment is between 5 and 250 μm, preferably between 6 and 120 μm, in particular between 12 and 100 μm, very particularly between 12 and 50 μm.

Preferably, the film consists of polyethylene terephthalate and has a thickness between 12 and 50 μηη. The carrier films may also contain other additives such as UV protectants or halogen-free flame retardants.

A suitable film is available under the trade name Hostaphan® RNK. This film is highly transparent, biaxially oriented and consists of three coextruded layers.

For the production of the film, it may be appropriate to add additives and other components which improve the film-forming properties, reduce the tendency to form crystalline segments and / or specifically improve or even worsen the mechanical properties.

The tensile strength of the film is preferably greater than 100 N / mm ² , preferably greater than 180 N / mm ² (in the longitudinal direction) and greater than 200 N / mm ² , preferably greater than 270 N / mm ² (in the transverse direction).

The elongation at break of the film is preferably less than 300 N / mm ² , preferably greater than 200 N / mm ² (in the longitudinal direction) and less than 300 N / mm ² , preferably greater than 120 N / mm ² (in the transverse direction).

The film significantly determines the tensile strength or elongation at break of the pressure-sensitive adhesive strip. The adhesive tape containing the film carrier preferably has the same tensile strength and elongation at break values as stated above. The support material may be equipped on one or preferably both sides with the PSA according to the invention. In the case of the adhesive tape provided on both sides with the pressure-sensitive adhesive of the invention, at least one layer forms the pressure-sensitive adhesive of the invention.

The pressure-sensitive adhesive tape is formed by partially or completely applying the adhesive to the carrier. The coating can also take the form of one or more strips in the longitudinal direction (machine direction), optionally in the transverse direction, but in particular it is full-surface. Furthermore, the adhesives can be applied in the manner of a grid dot by means of screen printing, whereby the dots of adhesive can also be distributed differently and / or differently, by webs connected in the longitudinal and transverse direction by gravure printing, by screen printing or by flexographic printing. The adhesive may be in dome form (made by screen printing) or in another pattern such as mesh, stripes, zigzag lines. Furthermore, it can also be sprayed on, for example, which results in a more or less irregular application pattern.

It is advantageous to use an adhesion promoter, a so-called primer layer, between the carrier and the adhesive or a physical pretreatment of the carrier surface to improve the adhesion of the adhesive to the carrier.

As primers, the known dispersion and solvent systems can be used, for example, based on isoprene- or butadiene-containing rubber, acrylate rubber, polyvinyl, polyvinylidene and / or cyclic rubber. Isocyanates or epoxy resins as additives improve the adhesion and in part also increase the shear strength of the pressure-sensitive adhesive. The adhesion promoter can also be applied by means of a coextrusion layer on one side of the carrier film. For example, flame treatment, corona or plasma or coextrusion layers are suitable as physical surface treatments.

Furthermore, the backing material (in the case of a single-sided adhesive tape) can be subjected to an antiadhesive physical treatment or coating on the reverse or top side, ie the adhesive mass side, in particular with a release agent or release (optionally blended with other polymers). Examples are stearyl compounds (for example polyvinyl stearyl carbamate, stearyl compounds of transition metals such as Cr or Zr, ureas of polyethyleneimine and stearyl isocyanate or polysiloxanes.) The term stearyl is synonymous with all straight or branched alkyls or alkenyls having a C number of at least 10, such as Example octadecyl.

Suitable release agents further include surfactant release systems based on long-chain alkyl groups such as stearylsulfosuccinates or stearylsulfosuccinamates, but also polymers which may be selected from the group consisting of polyvinyl stearyl carbamates such as Escoat 20 from Mayzo, Polyethyleniminstearylcarbamiden, chromium complexes of C14 to C28 Fatty acids and stearyl copolymers, as described for example in DE 28 45 541 A. Also suitable are release agents based on acrylic polymers with perfluorinated alkyl groups, silicones, for example based on poly (dimethyl-siloxanes) or fluorosilicone compounds. Next, the carrier material can be pre- or post-treated. Common pretreatments are hydrophobing, corona pretreatments such as IS Corona or plasma pretreatments, common post-treatments are calendering, tempering, laminating, stamping and covering. The adhesive tape may also be laminated with a commercially available release film or paper which is usually coated from a base material of polyethylene, polypropylene, polyester or paper coated on one or both sides with polysiloxane.

The pressure-sensitive adhesive tape according to the invention preferably has an adhesion to an aluminum substrate of at least 2.0 N / cm, preferably at least 6.0 N / cm and very particularly at least 8.0 N / cm.

For efficient production, it is of great advantage to produce a double-sided self-adhesive tape with only one formulation in order to minimize the cleaning effort of the system components.

In adhesive tapes made with the pressure-sensitive adhesive of the invention, however, it is advantageous that the two outer adhesive layers are designed such that they have similar bond strengths on both substrates to be bonded. This is especially true in the bonding of textile floor coverings on substrates.

Since the substrates to be bonded prove to be different affinities, the two sides must have very different bond strengths on a substrate. In order not to have to produce an adhesive tape with two different formulations, it has proven to be advantageous to adapt the layer thicknesses of the two sides. The layer thickness, which is glued to the less affine ground, should be greater. For the substrates used in practice, a layer thickness ratio of greater than or equal to 1: 2, but in particular 1: 4 has proven to be advantageous.

It is also advantageous to adjust this bond strength gradient by controlling the density of the two layers. For this purpose, it is sufficient to vary only a portion of a recipe ingredient, preferably the proportion of microballoons. Due to the high width of bonding substrates, the ratio of the two layer thickness or density ratios can be so great that a substantially non-foamed thin layer of adhesive is used for one side of the article according to the invention.

For a secure bonding of the temporary substrate, it is important that the PSA has a sufficiently high bond strength both to the temporary (carpet) and to the permanent substrate (aircraft floor). Pressure-sensitive adhesives according to the invention therefore preferably have an adhesive force on the backing of greater than 0.5 N / cm, preferably greater than 1 N / cm and very particularly preferably greater than 2 N / cm. The measurement of the adhesive force on the carpet is carried out analogously to the measurement of the bond strength on a steel plate, wherein previously a strip of the carpet, for example by means of a double-sided adhesive tape (with a sufficiently high bond strength) is fixed with the top on a steel plate.

The adhesive force of, for example, a natural rubber-based adhesive is usually adjusted by the weight ratio of the natural rubber to the adhesive resin or by the addition of plasticizers. It has been shown that for microballoon-containing, ie foamed masses, the choice of the adhesive resin is of crucial importance. Adhesive resins based on polyterpenes or other hydrocarbons (Cs resins, Cs / Cg resins, (partially) hydrogenated variants of Cs or Cs / Cg resins) sometimes do not achieve sufficiently high bond strengths. Particularly preferred therefore Terpenphenolharze, because with these sufficiently strong adhesive masses can be produced.

According to the invention, the adhesive tape formed with the pressure-sensitive adhesive is used to temporarily bond a temporary substrate to a permanent substrate.

According to a preferred embodiment, the temporary substrate is a textile floor covering such as a carpet and the permanent substrate is a substrate, preferably a metallic substrate, in particular aluminum, as it is installed in aircraft floors.

Floor coverings can be divided into textile coverings (carpet, fitted carpet) and non-textile coverings. Non-textile coverings include elastic coverings such as homogeneous plastic coverings (PVC, polyolefin coverings), multilayer plastic coverings, linoleum or cork coverings. Also include hard flooring (laminate or parquet), eventually tiles or stone pavement.

As a carpet (also knitted, spanned carpet) refers to a textile floor covering. Carpeting is any textile floor covering that can be laid all over in a room.

A carpet consists of several layers, of the carrier layer and the wear layer. The upper layer, the wear layer (Pol), consists of fibers. The fibers can be synthetic, natural or a mixture. Then, in some carpets, a middle layer with adhesive follows, which connects the fibers to the carrier fabric. The lower layer (carrier layer) is the carpet bottom, which can also consist of natural or synthetic materials.

If the temporary substrate in the form of the carpet is damaged and / or soiled, it should be able to be detached from the permanent substrate together with the pressure-sensitive adhesive of the invention. On the permanent substrate as few residues of the temporary composite should remain.

The adhesive of the invention fulfills these requirements.

Included within the scope of the invention is an adhesive tape having the PSA according to the invention, the PSA being applied in one layer to a liner, in particular with a thickness between 10 μηη and 3000 μηη, preferably between 10 μηη and 150 μηι.

Furthermore, an adhesive tape with the PSA according to the invention is within the inventive concept, wherein in the PSA layer, a carrier, in particular a film carrier is present.

Particularly advantageous due to the described and proven advantages of the adhesive tapes for bonding of temporary substrates such as textile floor coverings on permanent substrates such as substrates, in particular of aluminum, are suitable.

Further details, objects, features and advantages of the present invention will be explained in more detail with reference to several preferred embodiments illustrative figures. Show it

FIG. 1 shows a one-sided pressure-sensitive adhesive tape,

FIG. 2 shows a double-sided pressure-sensitive adhesive tape,

FIG. 3 shows a carrier-free pressure-sensitive adhesive tape (transfer adhesive tape). FIG. 1 shows a single-sided pressure-sensitive adhesive tape 1. The pressure-sensitive adhesive tape 1 has an adhesive layer 2 which has been produced by coating one of the previously described pressure-sensitive adhesive onto a carrier 3. The PSA coating is preferably between 10 and 50 g / m ² . In addition (not shown) may still be provided a release film, which covers the adhesive layer 2 before using the pressure-sensitive adhesive tape 1 and protects. The release film is then removed from the adhesive layer 2 prior to use.

The product structure shown in FIG. 2 shows a pressure-sensitive adhesive tape 1 with a carrier 3, which is coated on both sides with a pressure-sensitive adhesive and thus has two adhesive layers 2. The PSA per side is again preferably between 10 and 200 g / m ² .

Also in this embodiment, at least one adhesive layer 2 is preferably covered with a release film. With a rolled-up tape, this can be a release film optionally also cover the second adhesive layer 2. But it can also be provided more separation films.

Furthermore, it is possible that the carrier film is provided with one or more coatings. Furthermore, only one side of the pressure-sensitive adhesive tape can be provided with the inventive PSA and on the other side another PSA can be used.

The product structure shown in Figure 3 shows a pressure-sensitive adhesive tape 1 in the form of a transfer adhesive tape, that is, a carrier-free pressure-sensitive adhesive tape 1. For this purpose, the pressure-sensitive adhesive is coated on one side on a release film 4 and thus forms a pressure-sensitive adhesive layer 2. The pressure-sensitive adhesive composition is usually between 10 and 50 g / m ^{2 here} . Optionally, this pressure-sensitive adhesive layer 2 is still covered on its second side with a further release film. To use the pressure sensitive adhesive tape, the release liners are then removed.

As an alternative to release films, for example, release papers or the like can be used. In this case, however, the surface roughness of the release paper should be reduced in order to realize the smoothest possible PSA side.

Test Methods

The measurements are, unless otherwise stated, at a test climate of 23 ± 1 ° C and 50 ± 5% rel. Humidity carried out.

Adhesive strength aluminum, steel, carpet (back)

The peel strength (bond strength) was tested on the basis of PSTC-1.

A 2 cm wide strip of pressure-sensitive adhesive tape is adhered to the test substrate such as a steel plate, an aluminum plate or a carpet strip previously fixed to a solid steel substrate by rolling it five times with a 4 kg roller. The surface of the steel or aluminum plate is previously cleaned with acetone, the surface of the back of the carpet is not cleaned. The plate is clamped, and the self-adhesive strip over its free At a speed of 300 mm / min subtracted at a speed of 300 mm / min on a tensile tester under a peeling angle of 180 °, and determined the force required for this. The measurement results are given in N / cm and averaged over three measurements. The value is given as KK steel (bond strength steel) KK Alu (bond strength aluminum) and KK carpet (bond strength carpet back).

For the measurements carried out in this application the carpet Aero collection 5ED-121426 of the Desso Aviation Carpet was used. However, the good and advantageous results of the self-adhesive compositions according to the invention were also achieved on other different carpets of different manufacturers.

flame test

The flame tests were performed according to ASTM F501 (Airbus AITM 20005B). The test is considered passed if a maximum burning distance of 203 mm and a maximum burning time of 15 seconds are not exceeded. The samples were bonded to an aluminum plate before the test and kept at 23 ± 1 ° C and 50 ± 5% rel. For 3 days. Humidity conditioned.

absence of residues

In order to find a suitable measure for the determination of the residue freedom, an adhesive tape section (transfer adhesive tape) with a surface 5 x 20 cm is glued to a plate made of aluminum as a substrate. After 4 weeks of storage at 40 ° C on the permanent substrate, the tape is peeled off. The residual soil residues are determined by weighing the base plate and extrapolated to an area of one square meter.

In the following, the invention will be explained in more detail with reference to several examples, without thereby wanting to limit the invention unnecessarily. Examples

Example 1a Example 1 b Example 2 Comparative Example 5 Example 4

Standard 4 weeks KW resin

Raw material SolideinFesteinFesteinStamp scale [%] balance [%] balance [%] balance [%] balance [%]

Natural rubber (Type 41, 0 41, 0 41, 0 41, 0 41, 0 SVR 3L)

Piccotac 1 100E 37.0

Novares TK 90 12.0

Dertophene T 105 49.0 49.0 49.0 49.0

920 DU 40 5.0 5.0 5.0 5.0 5.0 Chemical

propellant

azodicarboxamide

Wingtack 10 5.0 5.0 5.0 5.0 5.0

DOPO

Flame retardants

ADP

Flame retardants

Comparative Comparison Comparative Example 3 Example 4 Example 1 Example 2 Example 3

Non-foamed Physical Chemical Flame Retardant Flame Retardant

Foaming foaming

Natural rubber (Type 43.0 43.0 42.0 37.3 33.9 SVR 3L)

Piccotac 1 100E

Novares TK90

Dertophene T 105 51, 0 51, 0 51, 0 44.5 40.5

920 DU 40 5.0 5.0

Azodicarboxamide 2.0

Wingtack 10 6,00 6,00 5,0 4,0 5,0

DOPO 9.2

Flame retardants

ADP 16.6 flame retardant

Piccotac 1 100-E aliphatic hydrocarbon resin

Eastman Chemical Middelburg B.V.

920 DU 40 micro balloons from Expancel

DOPO = (9,10-dihydro-9-oxy-10-phosphaphenanthrene-10-oxide)

ADP = aluminum diethylphosphinate

Using the adhesives prepared according to the above recipes, double-sided adhesive tapes are produced by applying the PSA to the top and bottom sides of a PET film etched with trichloroacetic acid on both sides over a thickness of 23 μm. Measurement results:

Comparative Comparison Example 3 Example 4 Example 1 Example 2 Example 3

Non-foamed Physical Chemical Flame Retardant Flame Retardant

Foaming foaming

Density 980 kg / m ³ 630 kg / m ³ 495 kg / m ³ 620 kg / m ³ 680 kg / m ³

Thick side Alu 20 μιη 32 μιη 40 μιη 32 μιη 29 μιη

KK aluminum 6.20 N / cm 7.50 N / cm 9.20 N / cm 4.8 N / cm 4.5 N / cm

Thick side carpet 85μιη 135 μιη 172 μιη 137 μιη 125 μιη

KK carpet 2.90 N / cm 1, 80 N / cm 2.40 N / cm 1, 2 N / cm 1, 7 N / cm

KK Alu 9.30 N / cm 8.50 N / cm 9.80 N / cm 7.9 N / cm 7.5 N / cm

Peel off the carpet no no no no no when removing

Layer Thickness Gradient 4.2 4.2 4.2 4.2 4.2

Flame test without fail did not pass passed passed additional FR

Residues on aluminum 1 g / m ² 13 g / m ² 15 g / m ² 4 g / m ² 4 g / m ² Example 1 b results from Example 1a by storage for 4 weeks (23 ± 1 ° C. and 50 ± 5% relative atmospheric humidity) in the bonded state. For the preferred application, it is important that the composite carpet (temporary substrate adhesive tape from the permanent substrate can be removed from the carpet without stretching even after a prolonged bonding period, without increasing the bond strength, and according to the invention, the bond strength on the permanent substrate does not increase over time.

In addition to the foaming with microballoons according to the invention, the comparative experiments also show the so-called chemical and physical foaming, in which case free unstabilized gas bubbles are produced in the polymer compound. It can be seen that both the chemical and the physical foaming when the adhesive tape of the invention is peeled off lead to an approximately central mass splitting.

According to the invention, products with very low density and very low residues (on the permanent substrate) can be produced. With chemical and physical foaming, however, residues increase with a reduction in density.

The PSA of the invention is further characterized in that the difference between the initial bond strength and the bond strength after storage in the bonded state (40 ° C, 28 d) is very low.

Preferably, the difference is at most 4 N / cm, most preferably at most 3 N / cm. The investigations have shown that, in particular, masses based on natural rubber (poly-cis-isoprene) fulfill the abovementioned conditions and are therefore preferred.

Claims

claims

Self-adhesive composition consisting of a mixture comprising:

• Rubber, in particular natural rubber

• at least one adhesive resin, the proportion of adhesive resins being 40 to 130 phr.

Expanded polymeric microspheres

Self-adhesive composition according to claim 1,

characterized in that

the proportion of tackifier resins is 80 to 120 phr.

Self-adhesive composition according to at least one of the preceding claims,

characterized in that

the density of the self-adhesive composition decreases after activation of the microballoons to up to 150 kg / m ³ and is preferably between 300 and 800 kg / m ³ .

Self-adhesive composition according to at least one of the preceding claims, characterized in that the self-adhesive composition can be removed as far as possible residue-free after bonding.

Self-adhesive composition according to Claim 1 or 2,

characterized in that

as adhesive resins Terpenphenolharze, in particular isolated, can be used.

Self-adhesive composition according to at least one of claims 1 to 3,

characterized in that

the proportion of the microballoons based on the total adhesive before expansion in the self-adhesive between greater than 0 wt .-% and 30 wt .-%, in particular between 1, 5 wt .-% and 10 wt .-%, each based on the total composition the pressure-sensitive adhesive is.

Self-adhesive composition according to at least one of the preceding claims,

characterized in that

the PSA has the following composition:

a) 30 wt .-% to 59.9 wt .-%, preferably 45 wt .-% to 53.5 wt .-% natural rubber

b) 40 wt .-% to 69.9 wt .-%, preferably 45 wt .-% to 55 wt .-% terpene phenolic resin c) from 0.1% by weight to 30% by weight, in particular from 1.5% by weight to 10% by weight, of expanded polymeric microspheres (based on unexpanded microballoons)

Self-adhesive composition according to at least one of the preceding claims,

characterized in that

the PSA has the following composition:

a) 30 wt .-% to 59.9 wt .-%, preferably 45 wt .-% to 53.5 wt .-% natural rubber

b) 40 wt .-% to 69.9 wt .-%, preferably 45 wt .-% to 55 wt .-% of at least one adhesive resin, in particular terpene phenolic resin

c) 0.1 wt .-% to 30 wt .-%, in particular between 1, 5 wt .-% and 10 wt .-% expanded polymeric microspheres (based on unexpanded microballoons) and d) 0 wt .-% to 20 % By weight, preferably up to 5 to 10% by weight, of further additives. 9. Self-adhesive composition according to at least one of the preceding claims,

characterized in that

the PSA has the following composition:

a) 45 wt .-% to 53.5 wt .-% natural rubber

b) 45% to 55% by weight terpene phenolic resin

d) 0 wt .-% of other additives

Self-adhesive composition according to at least one of the preceding claims,

characterized in that

the self-adhesive comprises further blending components such as plasticizers, aging inhibitors, processing aids, fillers, dyes, optical brighteners, stabilizers, in particular flame retardants.

1 1. Self-adhesive composition according to at least one of the preceding claims,

characterized in that

besides natural rubber, no further elastomeric polymer is present in the PSA.

12. Self-adhesive composition according to at least one of the preceding claims,

characterized in that

the pressure-sensitive adhesive flame retardants, in particular be added based on organic phosphorus compounds.

13. A self-adhesive composition according to at least one of the preceding claims,

characterized in that

the PSA is crosslinked.

14. Double-sided adhesive tape having at least one PSA according to at least one of the preceding claims, wherein the pressure-sensitive adhesive (s) have a thickness between 10 μηη and 600 μηη, preferably between 10 μηη and 500 μηη.

15. Adhesive tape with a pressure-sensitive adhesive according to at least one of the preceding claims, wherein in the PSA layer, a carrier, in particular a film carrier, especially polyester, especially polyethylene terephthalate, polyamide, polyimide or mono- or biaxially stretched polypropylene, is present.

16. Double-sided adhesive tape according to claim 15, where both PSAs are formulation-identical.

17. Double-sided adhesive tape according to claim 15, wherein the two pressure-sensitive adhesives have a layer thickness ratio of greater than 1, preferably 2, more preferably 4.

18. Double-sided adhesive tape according to claim 15, wherein the adhesives used have different densities.

19. Adhesive tape according to claim 15, wherein one of the two adhesives is unfoamed.

Use of an adhesive tape according to any one of claims 14 or 15 for the bonding of temporary substrates such as textile floor coverings on permanent substrates such as substrates, in particular metallic substrates, more particularly aluminum.