KR20190105140A - Adhesive strip with some foamed self-adhesive material - Google Patents

Abstract

The present invention relates to an adhesive strip having at least one layer (SK1) of self-adhesive material partially foamed into microballoons, wherein the degree of foaming of layer (SK1) is at least 20% and less than 100%. The invention also relates to a method of manufacturing the same, and in particular to the use thereof for adhesively bonding parts such as batteries and electronic devices, for example, especially mobile devices.

Description

Adhesive strip with some foamed self-adhesive material

The present invention relates to a pressure-sensitive adhesive strip having some foamed self-adhesive composition, to a process for its preparation, and to a combination of parts, for example, accumulators and electronic devices, for example, mobile devices. It is about a use.

Adhesive tapes are often used for the bonding of micro components, for example in devices in the consumer electronics industry. To enable this, it is essential that the shape of the adhesive tape section matches the part shape. In this case, demanding geometries are often, also, necessary, which are obtained by die-cutting of the adhesive tape. Accordingly, it is never uncommon for a component width of several millimeters or even less in a die-cut part. In the application of such sensitive adhesive tapes to parts, often die-cut parts are deformed.

It has been found to be advantageous to incorporate films, such as PET films, into adhesive tapes as intermediate laminas in order to suppress or at least reduce strain in order to absorb tensile forces in the application.

If the part is impacted, the use of this bond with adhesive tape is increasing. In particular, the impact resistant bond was found to be a bond with a viscoelastic, syntactically foamed core, a stabilizing film, and a pressure sensitive adhesive strip having two self adhesive bonding layers on the outer lamina.

Such pressure sensitive adhesive strips can exhibit such high performance that cohesive failure in pressure sensitive adhesive strips is observed under impact. The bond between the foamed core and the stabilizing film is broken and the foam and film are separated from each other.

Foamed pressure sensitive adhesive composition systems have been known for a long time and are described in the prior art.

In principle, the polymer foam can be produced in two ways. One way is by the effect of blowing gas, added on its own or formed by chemical reaction, and the second way is by the introduction of hollow beads into the material matrix. The foam formed by the latter pathway is referred to as syntactic foam.

In the case of syntactic foam, hollow beads, for example glass beads or hollow ceramic beads (microbeads) or microballoons, are introduced into the polymer matrix. As a result, in the syntactic foam, the voids are separated from each other, and the materials (gas, air) present in the voids are separated from the surrounding matrix by the membrane.

Compositions foamed with hollow microbeads are notable for a defined cell structure with a homogeneous size distribution of the foam cells. When using hollow microbeads, void-free closed cell foams are obtained, the characteristics of which include better sealing action against dust and liquid media compared to open-cell variants. In addition, chemically or physically foamed materials have a tendency to collapse irreversibly under pressure and temperature, and often exhibit lower cohesive strength.

Particularly advantageous properties can be achieved when the microbeads used for foaming are expandable microbeads (also referred to as "microballoons"). Due to its flexible, thermoplastic polymer shell, this class of foams has a higher adaptation capacity than foams filled with non-expandable, non-polymeric hollow microbeads (eg hollow glass beads). This has a better suitability for compensating for manufacturing tolerances, for example, in the case of injection molded parts, as well as better compensating for thermal stress due to its foam characteristics.

It is also possible to further influence the mechanical properties of the foam through the selection of the thermoplastic resin of the polymer shell. For example, even when the foam has a lower density than the matrix, it is possible to produce foams with higher cohesive strength than the polymer matrix alone. For example, conventional foam properties, such as the ability to adapt to rough substrates, can be combined with the cohesive strength for self-adhesive foams.

Among the devices of the consumer electronics industry, in the context of the present application, within the limits of electronic, optical and precision devices, in particular electronic, optical or precision devices, the International Classification of Goods and Services for the registration of marks for the Registration of Marks), devices classified in the ninth edition of the tenth edition (NCL (10-2013)), and also clocks and time-measurements according to the fourteenth category (NCL (10 2013)). Device,

For example, in particular

_● Scientific, marine, surveying, photographic, film, optical, weighing, measuring, signaling, monitoring, structural and indicating devices and instruments;

_• devices and appliances for conducting, converting, converting, storing, regulating and monitoring electricity;

_● image recording, processing, transmitting and reproducing apparatus, for example, television and the like;

_● sound recording, processing, transmitting and reproducing apparatus, for example, the broadcast apparatus, and the like;

_● computer, calculation unit and the data processing device, the mathematical instruments and devices, computer accessories, office equipment - for example, a printer, fax, copier, typewriter-, the data storage device;

_● Multi-function device and a communication device with a communication function, for example, a telephone and an answering machine;

_● chemical and physical measuring devices, control devices, such as battery chargers, Meter (multimeter), and the lamp current meter (tachometer);

_● nautical instruments and devices;

_● optical instruments and devices;

_● those for medical equipment and devices, and sportsmanship;

_● Clock and chronometer;

_● the solar cell module, for example, electrochemical dye solar cell, an organic solar cell, and a thin film battery;

_• Include extinguishing equipment.

Technological developments are increasingly moving toward smaller and lighter designs, in which the device is always possessed by the owner and can usually be carried. This is increasingly achieved by the realization of low weight and / or suitable size of such devices today. Such a device is also referred to as a mobile device or a portable device for the purposes of this specification. With this development trend, more and more (and) electronic components are provided in precision and optical devices, increasing the possibility of minimization. Due to the portability of mobile devices, they are subject to increased loads, in particular permanent movements associated with themselves impacting or dropping edges, touching other hard objects in the bag, or simply being carried in other ways. Is affected by mechanical load. However, mobile devices are also generally more affected by load due to moisture exposure, temperature effects, etc. than “floating” devices that are installed indoors and move little or no movement.

The present invention thus relates particularly preferably to mobile devices since the pressure-sensitive adhesive strips used according to the invention have particular advantages here because of their unexpectedly good, ie further improved properties (very high impact resistance). . A number of portable devices are listed below, wishing that the representative examples specifically set forth in the list below do not impose any unnecessary limitations on the subject matter of the present invention.

_● camera, a digital camera, shooting accessories (e. G., Light meter (light meter), a flash gun (flashgun), a diaphragm (diaphragm), the camera case, lens, etc.), a film camera, a video camera,

_● small computer (mobile computer (mobile computer), portable computers (handheld computer), handheld calculator), laptops, notebooks, netbooks (netbook), Ultrabooks (ultrabook), a tablet computer (tablet computer), handheld (handheld), Electronic diary and organizer (so-called "electronic organizer" or "personal digital assistant", PDA, palmtop, modem,

_● operation for computer accessory and the electronic device unit, for example, a mouse, a drawing pad (drawing pad), a graphics tablet (graphics tablet), a microphone (microphone), speaker (loudspeaker), a game console (games console), a game pad (game pad ), Remote control, remote operating device, touchpad,

_● monitor, a display, a screen, a touch-sensitive screen type (touch-sensitive screen) (screen sensor, a touch screen device (touchscreen device)), the projector (projector),

_● reading device for e-books (“E-books”),

_● Mini TV, Pocket TV, movie player, video player,

_● radio (including mini and pocket radio), Walkman (Walkman), disc man (Discman), Music player (music player), for example, CD, DVD, Blu-ray (Blue-ray), Cassette, USB, MP3 , Headphones,

_• cordless phones, cell phones, smartphones, two-way radios, hands-free telephones, human recall devices (pager, beeper),

_● portable defibrillator (mobile defibrillator), blood glucose meter, blood pressure monitor, the step counter (step counter), Pulsecomputer (pulse meter),

_● flashlight (torch), a laser pointer (laser pointer),

_● Mobile Detector (mobile detector), optical magnifiers (optical magnifier), binoculars (binocular), night vision devices (night vision device),

_● GPS device, a navigation device (navigation device), a portable interface device for satellite communication (portable interface device),

_● Data storage devices (USB stick (stick), an external hard drive (external hard drive), memory cards (memory card)),

_• Watches, digital watches, pocket watches, chain watches, stopwatches.

For such a device, a particular requirement for the adhesive tape is to have a high holding performance.

It is also important that the holding performance of the adhesive tape does not degrade when the mobile device, for example the mobile phone, falls to the floor and is impacted. Accordingly, the adhesive strip must have very high impact resistance.

EP 2 832 780 A1 relates to pressure sensitive adhesive foams comprising a crosslinking agent selected from the group of rubber elastomers, at least one hydrocarbon tackifier and a multifunctional (meth) acrylate compound.

JP 2010 / 070,655 A relates to a composition comprising a styrene-based thermoplastic elastomer (A), a tackifier (B) and a thermally expandable blowing agent in the form of microcapsules.

DE 10 2008 056 980 A1

A polymer blend consisting of thermoplastic and / or non-thermoplastic elastomers having at least one vinylaromatic block copolymer comprising a proportion of 1,2-bonded dienes in an elastomer block in an amount greater than 30% by weight,

At least one tackifying resin,

A self-adhesive composition consisting of a mixture comprising expanded polymeric microbeads.

WO 2009/090119 A1 is a pressure sensitive adhesive composition comprising an expanded microballoon, wherein the bonding force of the adhesive composition comprising the expanded microballoon is the same basis weight and formulation deflected by breakage of voids formed by the expanded microballoon. To a pressure-sensitive adhesive composition reduced by up to 30% compared to the binding strength of the adhesive composition of the present invention.

WO 2003/011954 A1 is a foamed pressure-sensitive adhesive article, wherein the article comprises a) a polymer comprising at least one styrene block copolymer and at least one polyarylene oxide, and b) at least one foamable polymer microbead It relates to a foamed pressure-sensitive adhesive article.

WO 00/006637 A1 is an article comprising a polymer foam having an essentially smooth surface having an R _a value of less than about 75 μm, wherein the foam contains a plurality of microbeads, at least one of which is an expandable polymer micro It relates to a bead-in item.

WO 2010/147888 A2 discloses a polymer, a plurality of at least partially expanded expandable polymer microbeads and a silicone having a surface area of at least 300 square meters per gram according to ASTM D1993-03 (2008), from 0.3% to 1.5% by weight. It relates to a foam comprising a dioxide.

DE 10 2015 206 076 A1 is a residue-free and non-destructive manner, essentially stretchable at the bonding surface, comprising a pressure-sensitive adhesive composition all foamed with a microballoon and at least one adhesive composition, optionally consisting of at least one intermediate carrier layer. A pressure-sensitive adhesive strip that can be detached back to a pressure-sensitive adhesive strip, the pressure-sensitive adhesive strip consisting solely of the mentioned adhesive composition layer and any intermediate carrier layer present, wherein one outer upper surface and one outer lower surface of the pressure-sensitive adhesive strip are A pressure sensitive adhesive strip is formed by an adhesive composition layer (s). Removable pressure sensitive adhesive strips are noteworthy for their pronounced impact resistance.

DE 10 2016 202 479 A1 describes a four-layer adhesive tape in which the foamed inner layer is further reinforced by a PET stabilized film. Due to this structure, it is particularly possible to provide an impact resistant adhesive tape.

Patent application DE 10 2016 209 707 from the same applicant as this document not published on the priority date of the present application discloses an inner layer (F) of a non-extensible film carrier, on one of the surfaces of the film carrier layer (F). A layer (SK1) consisting of a self-adhesive composition based on an acrylate composition and foamed on and based on an acrylate composition arranged and foamed on the opposite surface of the film carrier layer (F) from layer (SK1) A pressure sensitive adhesive strip consisting of three layers is described that includes a layer (SK2) of one self-adhesive composition. Due to this structure, it was likewise possible to provide particularly impact resistant adhesive tapes.

Likewise, EP 17 182 443, which is not published on the priority date of the present application, is disposed on one of the inner layer (F) of the non-extensible film carrier, the surfaces of the film carrier layer (F) and foamed with microballoons. A layer (SK1) of the self-adhesive composition based on the aromatic block copolymer composition, and a vinylaromatic block copolymer composition disposed on the opposite surface of the film carrier layer (F) from the layer (SK1) and foamed with a microballoon. A pressure-sensitive adhesive strip consisting of at least three layers, comprising a layer (SK2) of self-adhesive composition on the basis, wherein the average diameter of the cavities formed by the microballoons in the self-adhesive composition layers (SK1 and SK2) is in each case It relates to a pressure-sensitive adhesive strip independently of 20 to 60 μm. Pressure-sensitive adhesive strips have high impact resistance.

Likewise, EP 17 182 447, which is not published on the priority date of the present application, includes a pressure sensitive adhesive strip comprising at least one layer SK1 of a self-adhesive composition based on a vinylaromatic block copolymer composition foamed with a microballoon. As an example, the present invention relates to a pressure-sensitive adhesive strip having an average diameter of 45 to 110 μm of the cavity formed by the microballoons in the self-adhesive composition layer SK1. Pressure-sensitive adhesive strips have, in particular, improved lifetime under high temperature shear.

It is an object of the present invention in connection with the prior art to provide additional pressure sensitive adhesive strips having high impact resistance. Impact resistance is preferably further improved. In particular, such pressure sensitive adhesive strips are required in the production of mobile devices in which adhesive bonds with high impact resistance are implemented.

This problem is surprisingly solved by, according to the invention, a pressure sensitive adhesive strip of the general type as described in the independent claim 1. The subject matter of the dependent claims includes advantageous embodiments of the pressure sensitive adhesive strip.

Accordingly, the present invention provides a pressure-sensitive adhesive strip comprising at least one layer SK1, preferably exactly one layer SK1 of a partially foamed self-adhesive composition with microballoons MB, the layer SK1 The degree of foaming relates to pressure-sensitive adhesive strips that are at least 20% and less than 100%.

The pressure sensitive adhesive strips of the present invention with some foamed self-adhesive compositions are surprisingly similar in impact resistance to corresponding pressure sensitive adhesive strips with fully foamed self-adhesive compositions from the prior art, and often compared to these corresponding pressure sensitive adhesive strips. Further improved impact resistance. For example, impact resistance in the z direction (penetration impact resistance) and preferably, impact resistance in the x, y direction (lateral impact resistance) are similar or often further improved. In addition, pressure sensitive adhesive strips with some foamed self-adhesive compositions typically have improved bond strength (bonding force) compared to corresponding pressure sensitive adhesive strips with fully foamed self-adhesive compositions from the prior art.

The present invention also provides a process for producing such a pressure-sensitive adhesive strip, in which the self-adhesive composition layer SK1 partially foamed with microballoons and optionally the self-adhesive composition layer SK2 comprises an unexpanded microballoon. A process is produced by heat treating a corresponding self-adhesive composition layer at a temperature suitable for foaming at a temperature at which a desired degree of foaming is achieved after subsequent cooling of the layer.

The invention also relates to the use of pressure-sensitive adhesive strips for the joining of parts, for example accumulators and electronic devices, for example especially mobile devices, for example mobile phones. Regarding its property profile, the use of the pressure sensitive adhesive strips of the invention is contemplated in the automotive field, in construction, and in the printing industry.

When a layer of self-adhesive composition comprising an unexpanded microballoon, also referred to as a "unfoamed" self-adhesive composition layer in the context of the present invention, is treated with a suitable elevated temperature, the microballoon expands, This results in foaming of the layer. Heating of the microballoons increases the internal pressure of the blowing agent present therein, and the shell softens as the temperature further increases, at which time the microballoons expand. If the temperature is kept constant or further increased, this results in a much thinner shell and a much larger microballoon diameter through continuous expansion. Many unexpanded microballoon types are commercially available, which differ in nature in terms of their size and the starting temperature (75-220 ° C.) they are required for expansion. One skilled in the art recognizes that the temperature selected for foaming depends not only on the type of microballoon but also on the desired foaming rate. The absolute density of the foam decreases as a result of continuous foaming over a certain time. The conditions of the lowest density are referred to as full expansion, full foaming, 100% expansion or 100% expansion. In processes from the prior art, the microballoon-containing layer is typically fully expanded, because the desired properties of the layer will be achieved with a minimum microballoon content or the properties of the layer will be optimized with the provided microballoon content. Because it is assumed. Thus, full expansion is considered economically and technically advantageous. Subsequently, however, the expanded microballoons contract again at the selected foaming temperature, an overexpanded state is achieved, and the density of the layer increases again in the overexpanded state. The reason for the overexpansion is that the blowing agent begins to diffuse gradually through the shell and forms free gas bubbles in the surrounding polymer. Overexpansion is not desired, especially because the exhaust gas collects in the surrounding polymer, where it forms much larger free gas bubbles with increasing time, which reduces aggregation. In addition, these free gases diffuse over time into the environment through the surrounding polymer, and the polymer loses the foam content.

Conversely, when the layer is cooled before achieving full foaming, the expansion of the microballoons is stopped, which reduces the layer density. Here and below, the term “cooling” also includes passively allowing cooling, ie, typically at room temperature (20 ° C.), by removing heating. In addition, the term "cooling", according to the invention, also encompasses heating at relatively low temperatures. The result is some foamed layer. The foaming process with microballoons, through the proper selection of parameters of temperature and time, allows for infinitely variable adjustment of the degree of expansion of the microballoons, which, of course, also includes a degree of expansion of 100%, ie full foaming. . The energy input required to achieve the desired degree of expansion is also dependent on the thickness of the bonding layer to be foamed, and as the thickness increases, higher energy input is required. In practice, the various parameters are typically changed repeatedly until the desired degree of foaming is achieved. 3A-4E illustrate unfoamed, partially foamed, fully expanded, and overexpanded self-adhesive composition layers under a reflected light microscope.

The degree of expansion (expansion) of some foamed layers can be calculated as follows:

Degree of foaming = (density of layer containing unexpanded microballoons-density of some foamed layers) / (density of layer containing unexpanded microballoons-density of fully foamed layer)

Accordingly, the degree of foaming is a quotient of:

(i) the difference between the density of the layer comprising unexpanded microballoons and the density of some foamed layers, and

(ii) the difference between the density of the layer containing the unexpanded microballoons and the density of the fully foamed layer.

As an alternative to the determination of the degree of foaming through the density of unfoamed, partially foamed, and fully foamed layers, the degree of foaming is also similarly through the thickness of the unfoamed, partially foamed, and fully foamed layer. Can be determined.

The degree of foaming is in this case identified as the following share:

(i) the difference between the thickness of some foamed layers and the thickness of the layer comprising unexpanded microballoons, and

(ii) the difference between the thickness of the fully foamed layer and the thickness of the layer comprising unexpanded microballoons.

In this formula the layers comprising uninflated microballoons, some foamed layers and fully foamed layers, as well as the same in terms of basis weight and formulation, are the same in which some foamed and fully foamed layers are at suitable temperatures. And foaming of a layer comprising microballoons that have not been inflated for a suitable time.

The degree of foaming of some foamed layers can alternatively also be ascertained subsequently, i.e., originating from already foamed final products. Here, it is also possible to use one of the above formulas. The fully foamed layer can be provided by further foaming of some foamed layers at a suitable temperature and for a suitable time. However, the layer comprising the unexpanded microballoons is replaced in each case by those layers of the same basis weight and formulation saturated by the destruction of the voids in some foamed layers resulting from the expanded microballoons. In order to break the foamed microballoons in some foamed layers, the specimens tested are compressed under reduced pressure. The parameters of the press are as follows:

Temperature: 150 ℃

-Contact force: 10 kN

Vacuum: 0.9 bar (ie 0.9 bar gauge or 100 mbar absolute)

Compression time: 90 s

Thus, the degree of foaming of the fully expanded layer is 100%. In the case of an overexpanded layer, a negative degree of foaming is reported. What is found here is the rate of increase in the thickness lost again, or a decrease in density additionally obtained by subsequent overexpansion upon transition from the unexpanded state to the fully expanded state.

Some foamed self-adhesive composition layers of the present invention having a degree of foaming of from 20% to less than 100% have similar or more improved impact resistance compared to the corresponding fully expanded layer, depending on some degree of foaming which is clearly selected. The fact is that it is particularly surprising in that the microballoons in some foamed systems foam less significantly than in fully foamed systems. Accordingly, those skilled in the art will also expect that some foamed self-adhesive composition layers will have poorer impact resistance than the corresponding fully foamed self-adhesive composition layers.

Pressure sensitive adhesive strips of the invention having at least one self-adhesive composition partially foamed into microballoons are typically storage-stable. According to the invention this means that some foaming degree of some foamed self-adhesive composition (s) present in the pressure-sensitive adhesive strip, in each case, is 5 relative percent, at room temperature (20 ° C.) within 10 minutes. ), Preferably less than 1 relative percent.

Preferably, the pressure sensitive adhesive strip consists of a single self-adhesive composition layer SK1, whereby the pressure sensitive adhesive strip is a one-layer system. Such single layer adhesive tapes, double sided adhesive tapes with self-adhesive on both sides, are also referred to as "transfer tapes".

The self-adhesive composition layer (s) of the pressure-sensitive adhesive strip of the present invention typically have a thickness of 10 to 2000 μm. In a preferred embodiment, it has a thickness of less than 75 μm, more preferably less than 20 μm, even more preferably up to 15 μm, for example 10 μm. In an alternative, likewise preferred embodiment, the self-adhesive composition layer can also have a thickness of from 80 μm to 2000 μm and in particular from 100 to 300 μm, for example 150 μm.

In another preferred embodiment, the pressure-sensitive adhesive strip not only comprises layer SK1, but also comprises a layer T of (permanent) carriers, in particular a film carrier, wherein layer SK1 is a carrier layer T Is arranged on one of the surfaces of the. This pressure sensitive adhesive strip is a single sided adhesive tape. More preferably, the single-sided adhesive tape consists solely of layer SK1 and carrier layer T. According to the present application, the terms "pressure sensitive adhesive strip" and "adhesive tape" are used synonymously.

The layer T of carriers is also referred to synonymously in the context of this document, simply as a carrier or as a carrier layer.

In a particularly preferred embodiment, the pressure sensitive adhesive strip further comprises a layer SK2 of the self-adhesive composition arranged on the opposite surface of the carrier layer T from the layer SK1. Preferably, layer SK2 is based on a composition partially foamed with microballoons, wherein the degree of foaming of layer SK2 is at least 20% to less than 100%. This pressure sensitive adhesive strip is a double sided adhesive tape. More particularly, the double-sided adhesive tape consists solely of layer SK1, layer SK2, and carrier layer T.

In such single-sided or double-sided adhesive tapes, the (film) carrier layer preferably has a thickness of 5 to 150 μm. The film carrier layer may be non-stretchable, in which case it preferably has a thickness of 5 to 125 μm, more preferably 5 to 40 μm and in particular less than 10 μm, for example 6 μm. Alternatively, the film carrier layer may be stretchable, in which case the film carrier layer is preferably from 50 to 150 μm, more preferably from 60 to 100 μm and in particular from 70 to 75 μm, for example 70 Have a thickness of μm.

According to the present invention, "non-extensible film carrier" means more particularly preferably a film carrier having less than 300% elongation at break in both the longitudinal and transverse directions. The non-extensible film carrier is preferably, also preferably, independently less than 200%, more preferably less than 150%, even more preferably less than 100%, and especially 70 in both the longitudinal and transverse directions. Less than%, for example less than 50% elongation at break. The reported values are in each case based on test method R1 described below.

According to the present invention, " extensible film carrier " means more particularly preferably a film carrier having an elongation at break of at least 300%, both in the longitudinal and transverse directions. The stretchable film carrier also preferably has an elongation at break of at least 500%, for example at least 800%, independently in both the longitudinal and transverse directions. The reported values are in each case based on test method R1 described below.

Some foaming allows for the production of pressure sensitive adhesive strips, the layer of the microballoon-containing self-adhesive composition in particular having a very small thickness of less than 20 μm, for example 10 to 15 μm. In some such foamed self-adhesive composition layers, the average diameter of the voids formed by the microballoons is typically less than 20 μm, more preferably up to 15 μm, for example 10 μm. The average diameter of the voids formed by the microballoons in the self-adhesive composition layer is determined using the cryofracture edge of the pressure-sensitive adhesive strip in a scanning electron microscope (SEM) with a 500x magnification. The diameter of the microballoons in the tested self-adhesive composition layer, as seen in the scanning electron micrographs of the five different freeze breaking edges of the pressure sensitive adhesive strip, in each case is determined by graphical means and arithmetic of all identified diameters The mean constitutes the average diameter of the voids formed by the microballoons in the self-adhesive composition layer in the context of the present application. The diameter of the microballoons seen in the micrographs is determined by graphical means in such a way that the maximum size in any (two-dimensional) direction is estimated from the scanning electron micrographs for each individual microballoon in the layer of self-adhesive composition tested. Is determined and considered as its diameter. The use of such thin pressure-sensitive adhesive strips is particularly contemplated for the coupling of such components and electronic devices, especially when there is little space available for bonding, such as in mobile devices, for example mobile phones.

Accordingly, the pressure-sensitive adhesive strip in the form of a single-sided adhesive tape preferably has a thickness of 15 to 2150 μm. Accordingly, the pressure-sensitive adhesive strip in the form of a double-sided adhesive tape having a (permanent) carrier preferably has a thickness of 20 to 2300 μm.

In the present application, the "array" of layers SK1 and SK2 on the surface of the carrier layer T means that the layers SK1 and SK2 are in direct contact with the surface of the carrier layer T, ie , May refer to an array arranged directly on the surface. Alternatively, it is also possible at least one between the surface of the layer SK1 and the carrier layer T and / or between the opposite surface of the carrier layer T from the layer SK2 and the layer SK1. It can mean an arrangement in which additional layers are present. Preferably, in the pressure-sensitive adhesive strip of the invention with carrier layer T, layer SK1 and, if present, layer SK2 are formed from one of the surfaces of carrier layer T, or from layer SK1. Is in direct contact with the opposite surface of the carrier layer (T).

The outer surface of the bondable pressure-sensitive adhesive strip is preferably formed by the layer of some foamed self-adhesive composition of the present invention having a degree of foam of from 20% to less than 100%. This in particular effectively implements the advantages of the high impact resistance found in accordance with the invention. The most important meaning of impact resistance is some foam present in the self-adhesive composition layer (SK1) and layer (SK2).

Accordingly, the single-sided adhesive tape of the present invention is preferably a pressure-sensitive adhesive strip consisting of the carrier layer T and the self-adhesive composition layer SK1 arranged on one of the surfaces of the carrier layer T. The outer face of the pressure-sensitive adhesive strip available for bonding is formed by the layer of some foamed self-adhesive composition SK1 according to the invention.

Accordingly, the double-sided adhesive tape of the present invention having a carrier is likewise preferably a self-adhesive composition layer SK1 arranged on one of the surfaces of the carrier layer T, the carrier layer T, and the layer ( Pressure-sensitive adhesive strip consisting of a self-adhesive composition layer SK2 arranged on the opposite surface of the carrier layer T from SK1). One of the two outer faces of the pressure-sensitive adhesive strip available for bonding is formed by the layer of some foamed self-adhesive composition SK1 according to the invention. More preferably, layer SK2 is likewise based on a composition which is partially foamed into microballoons and has a foaming degree of at least 20% to less than 100%.

In the pressure-sensitive adhesive strip of the present invention having one or more layers of self-adhesive composition, preferably, all included self-adhesive composition layers are self-adhesive composition layers based on some foamed compositions with microballoons, wherein The degree of foaming of the layer is at least 20% and less than 100%. This class of pressure sensitive adhesive strips have particularly high impact resistance. Accordingly, the double-sided adhesive tape of the present invention having carriers partially foamed with microballoons such that both the self-adhesive composition layer (SK1) and layer (SK2) provide a degree of foaming of at least 20% to less than 100% is particularly high. It has impact resistance.

The layer (SK1) of the self-adhesive composition (SK1) and the layer (SK2) of the self-adhesive composition are simply layers in the context of this document, also as the self-adhesive composition layer (SK1) and the self-adhesive composition layer (SK2). (SK1) and layer (SK2) or else referred to as outer layer, adhesive composition layer or pressure-sensitive adhesive composition layer (SK1 and SK2). The term "outer" herein, in particular, preferably consists of a (permanent) carrier and some foamed layers SK1 and SK2, irrespective of any liner present on the outer side of the self-adhesive composition layer, It relates to a three-layer structure of the double-sided adhesive tape of the present invention (see further below).

Preferably, the degree of foaming of some foamed self-adhesive composition layer (SK1) and / or self-adhesive composition layer (SK2), preferably each layer (SK1) and layer (SK2) is independently 25% to 98 %, More preferably 35% to 95%, even more preferably 50% to 90% and especially 65% to 90%, for example 70% to 80%. Pressure-sensitive adhesive strips containing this layer of some foamed self-adhesive composition have particularly high impact resistance.

Preferably, in some foamed self-adhesive composition layer (SK1) and / or self-adhesive composition layer (SK2), preferably, the proportion of microballoons in each of layers SK1 and SK2 is in each case a self-adhesive. 12 wt% or less, preferably 0.25 wt% to 5 wt%, more preferably 0.5 wt% to 4 wt%, even more preferably 0.8 wt% to 3 wt%, based on the total composition of the composition layer, In particular from 1% to 2.5% by weight, for example from 1% to 2% by weight. Within this range, a pressure-sensitive adhesive strip containing a self-adhesive composition layer or such a self-adhesive composition layer and having particularly good impact resistance can be provided.

It is usually 400 to 990 kg / m 3, preferably 500 to 900 kg / m 3, more preferably 600 to 850 kg / m 3 and especially 650 to 800 kg / m 3, for example 700 to 800 kg / m 3. Some foamed self-adhesive composition layer (SK1) and / or self-adhesive composition layer having an absolute density of m 3 and / or a relative density of 0.35 to 0.99, preferably 0.45 to 0.90, and in particular 0.50 to 0.85 Cause SK2). Relative density describes the ratio of the density of some foamed self-adhesive compositions to the density of non-foamed self-adhesive compositions having the same formulation. Within this range, a pressure-sensitive adhesive strip containing a self-adhesive composition layer or such a self-adhesive composition layer and having particularly good impact resistance can be provided.

In a double-sided adhesive tape with a carrier, the self-adhesive composition layer (SK2) is preferably based on a composition partially foamed with microballoons, wherein the degree of foaming of the layer (SK2) is at least 20% to less than 100% to be. In a particularly preferred embodiment of the pressure-sensitive adhesive strip, this is the case where some foamed compositions of the two self-adhesive composition layers SK1 and SK2 are chemically identical and advantageously also have additives added thereto. Have the same symmetrical structure with respect to the composition of the layer in that the same and used in the same amount. More particularly, the pressure-sensitive adhesive strip is characterized in that both surfaces of the carrier T are equally pretreated and that the two self-adhesive composition layers SK1 and SK2 have the same thickness and density, ie two parts. With regard to both the chemical composition of the foamed self-adhesive layers SK1 and SK2 (including the additives present therein) and its structural composition, it is a fully symmetrical structure. “Fully symmetrical” relates, in particular, to the z direction of the pressure sensitive adhesive strip (“thickness,” the direction perpendicular to the face of the pressure sensitive adhesive strip), but of course additionally also the surface side (the x and y directions of the pressure sensitive adhesive strip). , Ie, length and width).

Preferably, the double-sided adhesive tape with a carrier has a structurally symmetrical structure in the z direction in that the two self-adhesive composition layers SK1 and SK2 have the same thickness and / or have the same density. According to the invention, it is also possible to realize self-adhesive composition layers SK1 and SK2 having the same thickness and / or the same density but chemically different double-sided adhesive tape.

The following references are expressly and without exception, and also relate to a fully symmetrical execution variant of the double-sided adhesive tape of the present invention.

The self-adhesive composition of the layers SK1 and SK2 is a pressure sensitive adhesive (PSA) composition, respectively. The terms "self-adhesive" and "pressure sensitive adhesive" are used synonymously in this context within the scope of this document.

The pressure sensitive adhesive composition exhibits permanent tack and adhesion, especially at the temperature of use (unless otherwise specified, at room temperature, ie 20 ° C.), by suitable addition of additional components such as tackifying resins, where appropriate. It is such a polymer composition that adheres upon contact with a plurality of surfaces and, in particular, adheres directly (with so-called "tackiness" (tackiness or touch-tackiness). This is possible, even at operating temperatures, without activation by solvents or heat, but usually wetting the substrate sufficiently to allow sufficient interaction on adhesion to be formed between the composition and the substrate, through the effect of rather large or small pressures. Can be mad. Essential influence parameters in this regard include pressure and contact time. The excellent properties of the pressure sensitive adhesive composition are derived, inter alia, from their viscoelastic properties. For example, adhesive compositions that adhere weakly or strongly; And also forming what can only be combined once and permanently, or which can be easily re-divided and repeatedly combined where appropriate so that the bond cannot be separated without breaking the adhesive and / or the substrate. It is possible.

The pressure sensitive adhesive composition can in principle be formed on the basis of polymers of different chemical properties. The pressure sensitive adhesive properties are characterized by the properties and proportions of the monomers used in the polymerization of the polymer on which the pressure sensitive adhesive composition is based, their average molecular weight and molar mass distribution, and the properties and amounts of additives such as tackifying resins, plasticizers, etc., to the pressure sensitive adhesive composition. Affected by arguments containing.

In order to achieve the viscoelastic properties, the monomers that underlie the polymer on which the pressure sensitive adhesive composition is based, and any additional components present in the pressure sensitive adhesive composition, in particular, may be used, particularly if the pressure sensitive adhesive composition is used at a temperature (ie, typically below room temperature, That is, to have a glass transition temperature (for DIN 53765) of less than 20 ° C.

In some cases, it is desirable to expand and / or shift the temperature range at which the polymer composition has pressure sensitive adhesive properties by suitable agglomeration-promoting means, such as crosslinking reactions (forming bridge-forming connections between macromolecules). May be advantageous. Accordingly, the application range of the pressure sensitive adhesive composition can be optimized through the setting between the flowability and cohesion of the composition.

The pressure sensitive adhesive composition has a permanent pressure sensitive adhesion at room temperature (20 ° C.), ie has a sufficiently low viscosity and high touch-adhesiveness to wet the surface of the individual adhesive substrate even at low contact pressures. The binding capacity of the adhesive composition is based on its adhesive properties and the resorption capacity is based on its cohesive properties.

In a preferred embodiment, the pressure-sensitive adhesive strip can be detached again, essentially without stretching, with no residue or breakdown on the bonding side. By "residue-free desorption" of the pressure-sensitive adhesive strip according to the invention is meant that no adhesive residue is left on the bonded surface of the components upon desorption. Furthermore, according to the invention, "nondestructive desorption" of the pressure-sensitive adhesive strip means that it does not damage, for example, destroy the bonded surface of the components upon desorption.

In order for the pressure-sensitive adhesive strip to be detachable again in a residue-free and non-destructive manner by stretching at the joining surface, it must have certain adhesive properties. For example, the tackiness of the pressure-sensitive adhesive strip should be clearly deteriorated during stretching. The lower the bonding performance in the stretched state, the less damage to the substrate upon desorption or the lower the risk of residue on the bonding substrate. This property is particularly evident in the case of pressure-sensitive adhesive compositions based on vinylaromatic block copolymers whose tack drops by less than 10% in the area of yield point.

In order for the pressure-sensitive adhesive strip to be easily detachable by stretching and in a residue-free manner, it must also have certain mechanical properties as well as the adhesive properties described above. Particularly advantageously, the ratio of breaking strength (tear strength) and stripping force is greater than two, preferably greater than three. The stripping force is such a force that must be consumed to re-detach the pressure-sensitive adhesive strip from the adhesive bond by stretching at the bonding surface. The stripping force consists of the force required as described above for the detachment of the pressure sensitive adhesive strip from the bonding substrate, and the force that must be consumed for the deformation of the pressure sensitive adhesive strip. The force required to deform the pressure sensitive adhesive strip depends on the thickness of the pressure sensitive adhesive strip. The force required for desorption is, on the contrary, independent of the thickness of the pressure-sensitive adhesive strip within the thickness range of the pressure-sensitive adhesive strip under consideration.

If reference is made to the following concerning the "self-adhesive composition layer" or "self-adhesive composition layer" according to a preferred embodiment of the invention, this is the layer (SK1), layer (SK2), unless expressly stated otherwise. Or else it may relate to both layers.

Self-adhesive composition layer usable according to the invention

The layer SK1 of the pressure-sensitive adhesive strip of the present invention is based on a self-adhesive composition partially foamed with microballoons. The layer SK2 of the pressure-sensitive adhesive strip of the present invention in the form of a double-sided adhesive tape with a carrier is likewise based on a self-adhesive composition, preferably partially foamed with microballoons.

The pressure sensitive adhesive composition layer present in the pressure sensitive adhesive strips of the present invention may be based on various polymer compositions, typically with tackifying resins. “Based on” a polymer or a particular polymer composition in this context typically means primarily the polymer, assuming the function of the elastomer component. Preferably, the polymer is provided solely as an elastomeric component, but in any case is provided in the range of at least 50% by weight based on the total content of all elastomeric components.

Preferably, this is based on chemically or physically crosslinked synthetic rubber compositions, such as vinylaromatic block copolymer compositions. Synthetic rubbers typically have high tackiness (by tackifying resins), achieve good results with very good bonding to polar and nonpolar substrates such as polypropylene and polyethylene, and are suitable for a broad spectrum of uses.

The pressure sensitive adhesive composition may likewise be preferably based on the acrylate composition. These are typically transparent, have good stability to aging, temperature, UV radiation, ozone, humidity, solvents, or plasticizers, and have very good binding to polar substrates.

Also contemplated are pressure sensitive adhesive compositions based on natural rubber compositions. This typically achieves good results by high tackiness (through tackifying resin), very good bonding to polar and nonpolar substrates, and residue-free removal.

(a) Self-adhesive composition layer based on vinylaromatic block copolymer composition

Layers SK1 and / or SK2 may be based on vinylaromatic block copolymer compositions.

Preferably, the vinylaromatic block copolymers used in layers SK1 and / or SK2 are in the form of block copolymers having the structure AB, ABA, (AB) _n , (AB) _n X or (ABA) _n X. At least one synthetic rubber is:

here,

A blocks are independently polymers formed by the polymerization of at least one vinylaromatic,

The B blocks are independently polymers formed by polymerization of conjugated dienes having 4 to 18 carbon atoms, or some hydrogenated derivatives of such polymers,

X is a radical of a coupling reagent or initiator,

n is an integer of 2 or more.

More preferably, all synthetic rubbers in the self-adhesive composition layer of the present invention are block copolymers having the structure AB, ABA, (AB) _n , (AB) _n X or (ABA) _n X as described above. . Accordingly, the self-adhesive composition layer of the present invention may also comprise a mixture of various block copolymers having the structure as described above.

Accordingly, suitable block copolymers (vinylaromatic block copolymers) comprise at least one rubber block B (soft block) and at least one glass block A (hard block). More preferably, at least one synthetic rubber in the self-adhesive composition layer of the present invention is a block copolymer having the structure AB, ABA, (AB) ₂ X, (AB) ₃ X or (AB) ₄ X, wherein The meaning is applicable to A, B and X. Most preferably, all synthetic rubbers in the self-adhesive composition layer of the present invention are block copolymers having the structure AB, ABA, (AB) ₂ X, (AB) ₃ X or (AB) ₄ X, wherein the above meanings Is applicable to A, B and X. More particularly, the synthetic rubber in the self-adhesive composition layer of the invention has an AB, ABA, (AB) ₂ X, (AB) ₃ X or (AB) ₄ X structure, preferably at least diblock copolymer AB and And / or triblock copolymer ABA and / or (AB) ₂ X. A mixture of block copolymers.

Also advantageous are mixtures of diblock copolymers and triblock copolymers and (AB) _n or (AB) _n X block copolymers, where n is at least 3.

Also advantageous are mixtures of diblock copolymers and multiblock copolymers and (AB) _n or (AB) _n X block copolymers, where n is at least 3.

Thus, the vinylaromatic block copolymer used may be, for example, diblock copolymer A-B in combination with another of the mentioned block copolymers. It is possible to use a fraction of the diblock copolymer to adjust the adaptation characteristic of the self-adhesive composition and its bonding strength. The vinylaromatic block copolymers used according to the invention preferably have a diblock copolymer content of 0% to 70% by weight and more preferably 15% to 50% by weight. Higher fractions of diblock copolymers in the vinylaromatic block copolymers result in a marked reduction in the cohesion of the adhesive composition.

The self-adhesive composition used is preferably a polymer block (i) (A block) formed mainly from vinylaromatics, preferably styrene, and at the same time a block (ii) (B block formed by polymerization of mainly 1,3-diene) ), For example block copolymers comprising butadiene and isoprene or based on two copolymers.

More preferably, the self-adhesive composition of the present invention is based on styrene block copolymers, for example, the block copolymer of the self-adhesive composition has a polystyrene terminal end.

Block copolymers formed from A and B blocks may contain the same or different B blocks. The block copolymer can have a linear A-B-A structure. It is likewise possible to use radially shaped block copolymers and star-shaped and linear multiblock copolymers. Additional components present may be A-B diblock copolymers. All the above-mentioned polymers can be used alone or in mixture with each other.

Especially in the vinylaromatic block copolymers used according to the invention, such as styrene block copolymers, in particular the fraction of polyvinylaromatics such as polystyrene is preferably at least 12% by weight, more preferably at least 18% by weight and particularly preferably At least 25% by weight, and likewise preferably at most 45% by weight and more preferably at most 35% by weight.

Rather than the preferred polystyrene blocks, the vinylaromatics used are also polymer blocks based on other aromatic-containing homo- and copolymers (preferably C ₈ to C ₁₂ aromatics) having glass transition temperatures higher than 75 ° C., for example For example, it may be an α-methylstyrene-containing aromatic block. In addition, it is also possible for the same or different A blocks to be present.

Preferably, the vinylaromatics for the formation of the A block include styrene, α-methylstyrene and / or other styrene derivatives. Accordingly, the A blocks may be in the form of homo- or copolymers. More preferably, the A block is polystyrene.

Preferred conjugated dienes as monomers for soft block B are, in particular, butadiene, isoprene, ethylbutadiene, phenylbutadiene, piperylene, pentadiene, hexadiene, ethylhexadiene, and dimethylbutadiene, and any desired such monomers. Selected from the group consisting of mixtures. The B blocks may also be in the form of homopolymers or copolymers.

More preferably, the diene conjugated as monomer for soft block B is selected from butadiene and isoprene. For example, soft block B is a polymer formed from polyisoprene, polybutadiene or some hydrogenated derivatives of one of these two polymers, for example polybutylene-butadiene or a mixture of butadiene and isoprene. Most preferably, the B block is polybutadiene.

A block in the context of the present invention is also referred to as "hard block". Correspondingly, the B block also refers to a "soft block" or an "elastomer block." This is the choice of the invention of the block according to its glass transition temperature (at least 25 ° C. for A blocks, more particularly at least 50 ° C., and for B blocks up to 25 ° C., more particularly at most, −25 ° C.). To reflect.

Preferably, the fraction of vinylaromatic block copolymers, such as, in particular, styrene block copolymers, based on the total self-adhesive composition layer, is at least 20% by weight, preferably at least 30% by weight, more preferably At least 35% by weight. Too low vinylaromatic block copolymer fractions result in relatively low cohesion of the pressure sensitive adhesive composition.

Based on the total self-adhesive composition, the maximum fraction of vinylaromatic block copolymers, eg, styrene block copolymers, in total is at most 75% by weight, preferably at most 65% by weight, more preferably at most 55% by weight. %to be. Too high vinylaromatic block copolymer fractions also rarely cause any pressure sensitive adhesion in the pressure sensitive adhesive composition.

Accordingly, the fraction of vinylaromatic block copolymers, for example, styrene block copolymers, preferably, based on the total self-adhesive composition, is preferably at least 20% by weight, more preferably at least 30% by weight in total. , More preferably at least 35% by weight, and at the same time up to 75% by weight, more preferably at most 65% by weight, most preferably at most 55% by weight.

Pressure-sensitive adhesion of the self-adhesive composition can be achieved by the addition of a tackifying resin that is miscible with the elastomeric phase. The self-adhesive composition generally includes at least one tackifying resin, as well as at least one vinylaromatic block copolymer, to increase the adhesion in the desired manner. The tackifying resin should be miscible with the elastomeric block of the block copolymer.

An "adhesive resin" (adhesive agent), according to the general understanding of a person skilled in the art, does not contain any tackifying resin and compares the pressure-sensitive adhesive composition (adhesiveness, intrinsic tackiness) in comparison with other identical pressure-sensitive adhesive compositions. It is understood to mean a low molecular weight oligomer or polymer resin that increases).

When the tackifying resin is present in the self-adhesive composition, it is preferably a DACP (diacetone alcohol cloud point) higher than 0 ° C., preferably higher than 10 ° C., at least 50 ° C., preferably at least 60 ° C. Mixed methylcyclohexane aniline point) and / or a resin having a softening temperature (ring & ball) of at least 70 ° C., preferably at least 100 ° C., is selected to a size of at least 75% by weight (based on total resin content). . More preferably, the tackifying resins mentioned at the same time have a DACP value of less than 50 ° C. if no isoprene block is present on the elastomer, or a DACP value of less than 65 ° C. if an isoprene block is present on the elastomer. Furthermore, more preferably, the described tackifying resins simultaneously have a MMAP value of up to 90 ° C. when no isoprene blocks are present on the elastomer, likewise up to 100 ° C. when isoprene blocks are present on the elastomer. Likewise, more preferably, the softening temperature of the tackifying resins mentioned is no greater than 150 ° C.

More preferably, the tackifying resin comprises at least 75% by weight hydrocarbon resin or terpene resin or mixtures thereof based on the total resin content.

Tackifiers that can be advantageously used for the pressure sensitive adhesive composition (s) are in particular hydrogenated and nonhydrogenated polymers of nonpolar hydrocarbon resins, for example dicyclopentadiene, C ₅ , C ₅ / C ₉ or C ₉ monomers. Identification of non-hydrogenated, partially, optionally or fully hydrogenated hydrocarbon resins based on a stream of monomers, and polyterpene resins based on α-pinene and / or β-pinene and / or δ-limonene. It became. The tackifying resins described above can be used alone or in mixtures. It is possible to use resins that are solid or liquid at room temperature (20 ° C.). The tackifying resins in the hydrogenated or non-hydrogenated form containing oxygen also optionally and preferably contain, in the adhesive composition, the total mass of resins such as rosin and / or rosin esters and / or terpene-phenolic resins. As a basis, up to 25% rate can be used.

In a preferred variant, the fraction of optionally available resins or plasticizers that are liquid at room temperature (20 ° C.) is 15% by weight or less, preferably 10% by weight or less, based on the total self-adhesive composition.

In a preferred embodiment, the self-adhesive composition layer is from 20% to 60% by weight of at least one tackifying resin, preferably the self-adhesive composition layer, based on the total weight of the self-adhesive composition layer. Thus, 30 wt% to 50 wt% of at least one tackifying resin is included.

Further additives which may be conventionally used are as follows:

_● a plasticizer, for example, a plasticizer oil, or a low molecular weight liquid polymers, e.g., low molecular weight polybutene, preferably a self-, based on the total weight of the adhesive composition has a ratio of 0.2% to 5% by weight,

Having a ratio of 0.2% to 1% by weight by weight based on the total weight of the adhesive composition, - _● 1 primary antioxidants, for example, a sterically hindered phenol, preferably self-

Having a ratio of 0.2% to 1% by weight by weight based on the total weight of the adhesive composition, - _● 2 primary antioxidant, e.g., phosphite, thioester or thioether, preferably self-

_● process stabilizers, for example, becomes a carbon radical scavenger, preferably a self-, based on the total weight of the adhesive composition has a ratio of 0.2% to 1% by weight,

_A light stabilizer, for example a UV absorber or a sterically hindered amine, preferably having a proportion of 0.2% to 1% by weight, based on the total weight of the self-adhesive composition,

_● the processing aid, preferably a self-, based on the total weight of the adhesive composition has a ratio of 0.2% to 1% by weight,

_An endblock reinforcement resin, preferably having a ratio of 0.2% to 10% by weight based on the total weight of the self-adhesive composition, and

Optionally, preferably elastomeric nature of the polymer adults _●; Correspondingly usable elastomers are inter alia pure hydrocarbons such as unsaturated polydienes such as polyisoprene or polybutadiene formed naturally or synthetically, essentially chemically saturated elastomers such as saturated ethylene -Propylene copolymers, α-olefin copolymers, polyisobutylenes, butyl rubbers, ethylene-propylene rubbers, and chemically functionalized hydrocarbons such as halogenated, acrylated, allyl or vinyl ether-containing polyolefins Including, preferably, having a proportion of 0.2% to 10% by weight based on the total weight of the self-adhesive composition.

The nature and amount of blend components can be selected as desired. Furthermore, the adhesive composition is in accordance with the present invention when it does not have some and preferably any mixtures mentioned in each case.

In one embodiment of the invention, the self-adhesive composition also comprises additional additives; Non-limiting examples include crystalline or amorphous oxides, hydroxides, carbonates, nitrides, halides, carbides or mixed oxides / hydroxides of aluminum, silicon, zirconium, titanium, tin, zinc, iron or alkali metal / alkaline earth metals. / Halide compounds. These are essentially aluminas such as aluminum oxide, boehmite, viarite, gibbsite, diaspore, and the like. Sheet silicates such as bentonite, montmorillonite, hydrotalcite, hectorite, kaolinite, boehmite, mica, vermiculite or mixtures thereof are very particularly suitable. However, it is also possible to use carbon black or additional carbon polymorphs, for example carbon nanotubes.

The adhesive composition may also be colored with a dye or pigment. The adhesive composition may be white, black or colored.

The metered plasticizer can be, for example, mineral oil, (meth) acrylate oligomers, phthalates, cyclohexanedicarboxylic acid esters, water soluble plasticizers, plasticizing resins, phosphates or polyphosphates.

Addition of surface-modified precipitated silica with silica, advantageously dimethyldichlorosilane, may be used to further enhance the thermal shear strength of the self-adhesive composition.

In a preferred embodiment of the invention, the adhesive composition consists solely of vinylaromatic block copolymers, tackifying resins, microballoons and optionally, the additives described above.

More preferably, the adhesive composition consists of the following composition:

● Vinyl aromatic block copolymer 20 wt% to 75 wt%

● Tackifying Resin 24.6 wt% to 60 wt%

● Microballoons 0.2 wt% to 10 wt%

● additive 0.2 wt% to 10 wt%

More preferably, the adhesive composition consists of the following composition:

● Vinyl aromatic block copolymer 35 wt% to 65 wt%

● Tackifying Resin 34.6 wt% to 45 wt%

● Microballoons 0.2 wt% to 10 wt%

● additive 0.2 wt% to 10 wt%

More preferably, the adhesive composition consists of the following composition:

● Vinyl aromatic block copolymer 30 wt% to 75 wt%

● Tackifying Resin 24.8 wt% to 60 wt%

● Microballoons 0.2 wt% to 10 wt%

The self-adhesive composition (SK1) of the present invention was partially foamed into the microballoons, and the self-adhesive composition (SK2) of the present invention was preferably partially foamed into the microballoons. Some foaming is typically achieved in each case by the introduction and subsequent expansion of the microballoons.

"Microballoon" is understood to mean a hollow microbead that is elastic and thus expandable in its bottom state with a thermoplastic polymer shell. These beads are filled with a low boiling liquid or liquefied gas. Shell materials used are in particular polyacrylonitrile, PVDC, PVC or polyacrylates. Suitable low boiling liquids are, in particular, hydrocarbons from lower alkanes, such as isobutane or isopentane, enclosed in the polymer shell under pressure as liquefied gas.

In particular, the action of the microballoons by the action of heat causes softening of the outer polymer shell. At the same time, the liquid blowing gas present in the shell is converted into its gaseous state. This causes irreversible expansion and three-dimensional expansion of the microballoons. Full expansion was achieved when internal pressure and external pressure were balanced. According to the invention, expansion is stopped in advance by cooling or by allowing cooling to cause a degree of foaming of at least 20% to less than 100%. Since the polymer shell is preserved, what is achieved is a closed-cell foam.

Many unexpanded microballoon types are commercially available, which differ in nature in terms of their size and starting temperature (75-220 ° C.) required for expansion. An example of a commercially available unexpanded microballoon is the Expancel® DU product (DU = dry unexpanded) from Akzo Nobel. In the product name Expancel xxx DU yy, "xxx" indicates the composition of the microballoon mixture and "yy" indicates the size of the microballoon in the expanded state.

Unexpanded microballoon products are also in the form of aqueous dispersions having a solid / microballoon content of about 40% to 45% by weight, and additionally also in the form of polymer-bound microballoons (masterbatches), for example , Ethylene-vinyl acetate with a microballoon concentration of about 65% by weight. Both masterbatch and microballoon dispersions, such as DU products, are suitable for the production of the foamed self-adhesive compositions of the invention.

Some expanded self-adhesive compositions (SK1 and / or SK2) of the present invention may also be formed to a certain degree with pre-expanded, ie, some expanded microballoons. In the case of this group, some expansion already occurs before mixing into the polymer matrix.

Already in some expanded microballoon-type processing, due to its low density in the polymer matrix into which the microballoons are introduced, it is likely that the microballoons will tend to float, ie rise upwards in the polymer matrix during processing operations. It is possible. This causes a heterogeneous distribution of microballoons in the layer. In the upper region of the layer (z direction), more microballoons are found in the lower region of the layer, thus allowing a density gradient to be established across the layer thickness.

In order to almost or very substantially avoid this density gradient, according to the invention only a low level in the polymer matrix of layer (SK1) or (SK2) or, preferably, both (SK1) and (SK2) In any case, preference is given to introducing pre-expanded microballoons. Only after being introduced into the layer, the microballoons expand to the desired degree of foaming. In this way, a more homogeneous distribution of the microballoons in the polymer matrix is obtained.

Preferably, the microballoons are selected such that the ratio of the density of the polymer matrix to the density of the microballoons (non-preexpanded or only slightly preexpanded) introduced into the polymer matrix is 1 to 1: 6. Thereafter, some expansion follows immediately or occurs directly in the introduction process. In the case of solvent-containing compositions, the microballoons are preferably expanded only after introduction, coating and drying (solvent evaporation). Thus, according to the invention, it is preferred to use DU products.

If some foaming is achieved by the microballoons, the microballoons can be fed into the formulation as batches, pastes or unblended or blended powders. In addition, these may be suspended in a solvent.

The self-adhesive composition (SK1 or SK2) of the present invention comprising expandable hollow microbeads may additionally also contain non-expandable hollow microbeads. It is important to note that almost all gas-containing cavities are permanently closed by an impermeable membrane, and such membranes are elastic and thermoplastically extensible polymer mixtures, or, for example, elastic, ie spectrum of temperatures possible in plastic processing Within, it does not matter whether it is made of non-thermoplastic glass.

(b) Self-adhesive composition layer based on acrylate composition

In another preferred embodiment, the self-adhesive composition layer (SK1) and / or the self-adhesive composition layer (SK2), preferably both the layer (SK1) and the layer (SK2) are based on the acrylate composition.

In one embodiment, the self-adhesive composition used is (meth) acrylic acid and esters thereof having 1 to 25 carbon atoms, maleic acid, fumaric acid, and / or itaconic acid and / or esters thereof, substituted (meth) Acrylamide, maleic anhydride and other vinyl compounds, for example vinyl esters, in particular vinyl acetate, vinyl alcohol and / or vinyl ethers. The residual solvent content should be less than 1 weight percent.

Another preferred embodiment is a pressure sensitive adhesive composition comprising a polyacrylate polymer. It is a polymer obtainable by free-radical polymerization of acrylic monomers, which is also understood to mean methacryl monomers and optionally further copolymerizable monomers.

According to the invention, it may be a polyacrylate crosslinkable with an epoxy group. Thus, the monomers or comonomers used may preferably be functional monomers capable of crosslinking with epoxy groups, the monomers used here being in particular acid groups (especially carboxylic acid, sulfonic acid or phosphonic acid groups) and / or hydrides. Preferred are monomers which contain monomers having hydroxyl groups and / or acid anhydride groups and / or epoxy groups and / or amine groups, and which contain carboxylic acid groups. It is particularly advantageous that the polyacrylates comprise polymerized acrylic acid and / or methacrylic acid.

Additional monomers that can be used as comonomers for polyacrylates include, for example, acrylic and / or methacrylic acid esters having up to 30 carbon atoms, vinyl esters of carboxylic acids having up to 20 carbon atoms, 20 Vinylaromatic compounds having the following carbon atoms, ethylene unsaturated nitriles, vinyl halides, vinyl ethers of alcohols containing 1 to 10 carbon atoms, aliphatic hydrocarbons having 2 to 8 carbon atoms and 1 or 2 double bonds Or mixtures of these monomers.

Preferably, the acrylate composition of the self-adhesive composition layer is formed using polyacrylate, which may be derived from the following monomer composition:

(i) acrylic acid (ester) and / or methacrylic acid (ester) of the formula

CH ₂ = C (R ¹ ) (COOR ² )

(Wherein R ¹ is H or CH ₃ and R ² is H, or a linear, branched or cyclic, saturated or unsaturated alkyl radical having 1 to 30, more particularly 4 to 18 carbon atoms),

(ii) olefinically unsaturated comonomers, optionally with functional groups causing crosslinking with epoxy groups,

(iii) additional acrylate and / or methacrylate and / or olefinically unsaturated monomers, optionally copolymerizable with component (i).

Preferably, (i) comprises acrylic esters and / or methacrylic esters of the formulas mentioned.

More preferably, in order to use the polyacrylate as a pressure sensitive adhesive, the proportions of the corresponding components (i), (ii) and (iii) are chosen such that the polymerization product has a glass transition temperature of not more than 15 ° C in particular.

The monomer of component (i) is selected at a ratio of 45% to 99% by weight, the monomer of component (ii) is selected at a ratio of 1% to 15% by weight, and the monomer of component (iii) is 0% by weight. It is very advantageous to produce pressure sensitive adhesive compositions selected in proportions of from 40 to 40% by weight (the numbers being based on the monomer mixture for the "base polymer", ie without the addition of any additives, eg resin, to the final polymer). One).

The monomers of component (i) are in particular plasticized and / or nonpolar monomers. For monomer (i), preference is given to using acrylic monomers comprising acrylic and methacrylic esters having alkyl groups of 4 to 18 carbon atoms, preferably 4 to 9 carbon atoms. Examples of such monomers include n-butyl acrylate, n-butyl methacrylate, n-pentyl acrylate, n-pentyl methacrylate, n-amyl acrylate, n-hexyl acrylate, hexyl methacrylate, n- Heptyl acrylate, n-octyl acrylate, n-octyl methacrylate, n-nonyl acrylate, isobutyl acrylate, isooctyl acrylate, isooctyl methacrylate and their branched isomers, for example 2 Ethylhexyl acrylate or 2-ethylhexyl methacrylate.

For component (ii), preference is given to using monomers having functional groups selected from the following list: hydroxyl, carboxyl, sulfone or phosphonic acid groups, acid anhydrides, epoxides, amines.

Particularly preferred examples of the monomer (ii) include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, aconitic acid, dimethylacrylic acid, β-acryloyloxypropionic acid, trichloroacrylic acid, vinylacetic acid, vinyl phos. Phonic acid, itaconic acid, maleic anhydride, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, 6-hydroxyhexyl methacrylate, allyl alcohol, glycidyl Acrylate, glycidyl methacrylate.

Monomers mentioned as examples for component (iii) include methyl acrylate, ethyl acrylate, propyl acrylate, methyl methacrylate, ethyl methacrylate, benzyl acrylate, benzyl methacrylate, secondary-butyl acrylate , t-butyl acrylate, phenyl acrylate, phenyl methacrylate, isobornyl acrylate, isobornyl methacrylate, tert-butylphenyl acrylate, tert-butylphenyl methacrylate, dodecyl methacrylate Latex, isodecyl acrylate, lauryl acrylate, n-undecyl acrylate, stearyl acrylate, tridecyl acrylate, behenyl acrylate, cyclohexyl methacrylate, cyclopentyl methacrylate, phenoxyethyl acrylic Latex, phenoxyethyl methacrylate, 2-butoxyethyl methacrylate, 2-butoxyethyl acrylate, 3,3 , 5-trimethylcyclohexyl acrylate, 3,5-dimethyladamantyl acrylate, 4-cumylphenyl methacrylate, cyanoethyl acrylate, cyanoethyl methacrylate, 4-biphenyl acrylate, 4- Biphenyl methacrylate, 2-naphthyl acrylate, 2-naphthyl methacrylate, tetrahydrofurfuryl acrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, dimethylaminoethyl acrylate, dimethyl Aminoethyl methacrylate, 2-butoxyethyl acrylate, 2-butoxyethyl methacrylate, methyl 3-methoxyacrylate, 3-methoxybutyl acrylate, phenoxyethyl acrylate, phenoxyethyl methacrylate Latex, 2-phenoxyethyl methacrylate, butyldiglycol methacrylate, ethylene glycol acrylate, ethylene glycol monomethyl acrylate, Methoxy polyethylene glycol methacrylate 350, methoxy polyethylene glycol methacrylate 500, propylene glycol monomethacrylate, butoxy diethylene glycol methacrylate, ethoxy triethylene glycol methacrylate, octafluoropentyl acrylate, octa Fluoropentyl methacrylate, 2,2,2-trifluoroethyl methacrylate, 1,1,1,3,3,3-hexafluoroisopropyl acrylate, 1,1,1,3,3 , 3-hexafluoroisopropyl methacrylate, 2,2,3,3,3-pentafluoropropyl methacrylate, 2,2,3,4,4,4-hexafluorobutyl methacrylate, 2,2,3,3,4,4,4-heptafluorobutyl acrylate, 2,2,3,3,4,4,4-heptafluorobutyl methacrylate, 2,2,3,3 , 4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctyl methacrylate, dimethylaminopropylacrylamide, dimethylaminopropylmethacrylamide, N- (1- Methyl undecyl) acrylamide, N- (n-butoxymethyl) acrylamide, N- (butoxymethyl) methacrylamide, N- (ethoxymethyl) acrylamide, N- (n-octadecyl) acrylamide And also N, N-dialkyl-substituted amides such as N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N-benzylacrylamide, N-isopropylacrylamide, N- Tert-butylacrylamide, N-tert-octylacrylamide, N-methylol acrylamide, N-methylol methacrylamide, acrylonitrile, methacrylonitrile, vinyl ethers, for example vinyl methyl ether , Ethyl vinyl ether, vinyl isobutyl ether, vinyl esters, for example vinyl acetate, vinyl chloride, vinyl halide, vinylidene chloride, vinylidene halide, vinylpyridine, 4-vinylpyridine, N-vinylphthalimide, N Vinyllactam, N-vinylpyrrolidone, styrene, α- and p-methylstyrene, α-butylstyrene , 4-n-butylstyrene, 4-n-decylstyrene, 3,4-dimethoxystyrene, macromonomers such as 2-polystyreneethyl methacrylate and poly (methylmethacrylate) ethyl methacrylate have.

The monomers of component (iii) may advantageously be selected such that they also contain functional groups which assist subsequent radiation-chemical crosslinking (eg by electron beam, by UV). Suitable copolymerizable photoinitiators include, for example, benzoin acrylate and acrylate-functionalized benzophenone derivatives. Monomers that assist crosslinking by electron impact include, for example, tetrahydrofurfuryl acrylate, N-tert-butylacrylamide, allyl acrylate, but this enumeration is not definite.

The pressure sensitive adhesive composition may also comprise a crosslinking agent, in particular a crosslinking agent based on epoxides. The materials containing epoxy groups used are in particular multifunctional epoxides, ie having at least two epoxy units per molecule (ie at least bifunctional). These may be aromatic or aliphatic compounds. Epoxy-based crosslinkers can also be used in oligomeric or polymeric form.

The mixture of acrylates may also more preferably have the following composition:

(I) 90% to 99% by weight of n-butyl acrylate and / or 2-ethylhexyl acrylate,

(II) ethylenically unsaturated monomers having from 1% to 10% by weight of acid or acid anhydride functionality

Here, the sum total of (I) and (II) becomes 100 weight% preferably.

Preferably, monomer (I) more preferably consists of a mixture of the same part of 2-ethylhexyl acrylate and n-butyl acrylate.

Useful monomers (II) advantageously include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid and / or maleic anhydride. Preference is given to acrylic acid or methacrylic acid, optionally two mixtures.

In order to achieve pressure sensitive adhesive properties, the adhesive composition should preferably be above its glass transition temperature at the processing temperature in order to have viscoelastic properties. Accordingly, the glass transition temperature of the pressure sensitive adhesive formulation (polymer-tackifier mixture) is less than + 15 ° C.

Possible additions of tackifiers inevitably increase the glass transition temperature by about 5 to 40 K depending on the amount added, compatibility and softening temperature. Accordingly, acrylate copolymers having a glass transition temperature of 0 ° C. or less are preferred.

Likewise, preferably, the pressure sensitive adhesive composition comprises at least two components:

(P) a first, polyacrylate-based component, ie a polyacrylate component, and a second, elastomer-based polymer component, ie, preferably one or more, that is immiscible with the (E) polyacrylate component. An elastomer component formed by or comprising at least one synthetic rubber.

The polyacrylate-based polymer component (P) is in a proportion of 60% to 90% by weight, more preferably 65% to 85% by weight of the total of the two components (P) and (E) (100% by weight). And the elastomer-based polymer component (E) is preferably present in a proportion of 10% to 40% by weight, more preferably 15% to 35% by weight. The overall composition of the adhesive composition may in particular be limited to these two components, but it is also possible for other additional components to be present, such as additives, and the like.

According to the invention, the second polymer component (elastomer component (E)) is essentially immiscible with the first polymer component (polymer component (P)) such that the adhesive composition in the adhesive composition layer is at least two Exist as distinct phases. More particularly, one phase forms a matrix and the other phase forms a plurality of domains arranged in the matrix.

Homogeneous mixtures are materials mixed at the molecular level, whereby the homogeneous system is a single phase system. Base materials are referred to in a synonymous manner in the context of this document as being "homogeneously miscible" and "commercially compatible". Thus, two or more components are not "homogeneously miscible" and "commercially compatible" synonymously when they do not form a homogeneous system after intimate mixing and are at least two phases. Synonymously "some homogeneously miscible" and "some commercially compatible" components form at least two phases upon intimate mixing with one another (eg, by shearing, in the melt or solution and subsequently by removing the solvent). Each of these is considered as abundant in one of the components, but one or both of the phases may each contain more or less portions of the other components in a homogeneous mixture.

The polyacrylate component (P) is preferably a homogeneous phase. Elastomeric component (E) may be essentially homogeneous, as known from microphase-separated block copolymers, or may itself have intrinsic polyphasicity. In the present context, the polyacrylate component and the elastomer component are chosen such that after intimate mixing, these are not inherently miscible at 20 ° C. (ie, typical use temperatures for adhesive compositions). “Essentially immiscible” is not homogeneously miscible with one another, such that no phase homogeneous mixture contains a proportion of a second component, or the components are partially miscible with one another at such a slight level, That is, one or both components can only homogeneously absorb a small proportion of the individual other components, and some miscibility is not essential to the present invention, that is, it is not detrimental to the teachings of the present invention. In such cases, the corresponding components are considered in the context of this document to be "essentially free of" individual other components.

Thus, the adhesive composition used according to the invention is present in at least a biphasic morphology at room temperature (20 ° C.). Very preferably, the polyacrylate component (P) and the elastomer component (E) are not essentially homogeneously miscible within the temperature range of 0 ° C to 50 ° C, even more preferably -30 ° C to 80 ° C.

In the context of this document, components are defined as “essentially miscible with one another”, in particular when the formation of at least two stable phases can be detected physically and / or chemically, wherein one phase is one component, ie , Abundantly in the polyacrylate component (P), and the second phase is rich in other components, that is, the elastomer component (E). One example of a suitable analysis system for phase separation is scanning electron microscopy. However, phase separation can also be recognized, for example, in that different phases have two independent glass transition temperatures. Phase separation exists when, according to the present invention, it can be manifested by at least one of the analytical methods.

Phase separation, in particular, is one component (essentially formed from one of the components and free of other components) in a continuous matrix enriched with other components (essentially formed from other components and without the first component). It can be implemented in that there are abundant distinct regions ("domains").

Phase separation for the adhesive composition used according to the invention takes place in particular in that the elastomer component (E) is present in dispersed form in the continuous matrix of the polyacrylate component (P). The region (domain) formed by the elastomer component (E) preferably has an essentially spherical form. The regions (domains) formed by the elastomeric component (E) can also escape from the spherical shape and in particular can be distorted, eg long and oriented in the coating direction. The size of the elastomeric domain of the largest dimension is typically 0.5 μm to 150 μm, in particular 1 μm to 30 μm, although this need not be the case. Other domain forms, for example sheet or rod forms, are likewise possible, where they can also deviate from the ideal structure in terms of their shape, for example bent or distorted.

Each of the polyacrylate component (P) and elastomer component (E) is a homopolymer, copolymer, or mixture of polymers (homopolymer and / or copolymer), and optionally, additives (co-components, additives) Is done. In the simplified form, the base polymer component is referred to below as "base polymer," but this is not intended to exclude polymer mixtures for individual base polymer components, and correspondingly, "polyacrylate base polymer" is a polyacrylate. It is understood to mean the base polymer component of the component, and “elastomer base polymer” is understood to mean the base polymer component of the elastomer component of the adhesive composition.

Each of the polyacrylate component (P) and / or the elastomer component (E) may be in the form of a 100% system, ie based solely on its individual base polymer component, without further addition of resins, additives, and the like. . In a further preferred manner, one or both of these two components have been mixed with the base polymer component as well as additional components such as a resin.

In an advantageous embodiment of the invention, the polyacrylate component (P) and the elastomer component (E) consist solely of their individual base polymer components, so that no further polymer components are present, in particular the resin is present. I never do that. In another development, the entire adhesive composition does not contain any additional ingredients other than the two base polymer components.

The polyacrylate-based adhesive composition or polyacrylate component (P) is particularly advantageously mixed with one or more crosslinking agents for chemical and / or physical crosslinking. However, since radiation-chemical crosslinking of the polyacrylate component (P) is also possible in principle, a crosslinking agent is not necessarily present.

Crosslinkers can react with suitable groups of polymers that are crosslinked under selected crosslinking conditions, in particular functional groups, thereby binding two or more polymers or polymer moieties to each other (forming a "bridge") and thus crosslinking It is usually a low molecular weight compound, in particular a bi- or multifunctional compound, which can produce a polymer or a network of polymers. This generally increases cohesion. The degree of crosslinking depends on the number of bridges formed.

In the present context, crosslinkers are in principle all crosslinking systems known to those skilled in the art for the formation of covalent, coordinating, or associative linkage systems with suitably modified (meth) acrylate monomers, depending on the nature of the polymer selected and the functional groups thereof. Examples of chemical crosslinking systems are di- or polyfunctional isocyanates or di- or polyfunctional epoxides or di- or polyfunctional hydroxides or di- or polyfunctional amines or di- or polyfunctional acid anhydrides. Combinations of different crosslinkers can likewise be considered.

Further suitable crosslinkers include chelating formers which, in combination with acid functionality in the polymer chain, form complexes that act as crosslinking points.

For effective crosslinking, it is particularly advantageous for at least some of the polyacrylates to have functional groups which can react with the individual crosslinkers. For this purpose, preference is given to using monomers having functional groups selected from the group comprising hydroxyl, carboxyl, sulfo or phosphonic acid groups, acid anhydrides, epoxides, amines.

Particularly preferred examples of monomers for polyacrylates include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, aconitic acid, dimethylacrylic acid, β-acryloyloxypropionic acid, trichloroacrylic acid, vinylacetic acid, Vinylphosphonic acid, maleic anhydride, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, 6-hydroxyhexyl methacrylate, allyl alcohol, glycidyl acrylic Latex, glycidyl methacrylate.

0.03 to 0.2 parts by weight, in particular 0.04 to 0.15 parts by weight of N, N, N ', N'-tetrakis (2,3-epoxypropyl) -m- based on 100 parts by weight of the polyacrylate base polymer as crosslinking agent. It was found to be particularly advantageous to use xylene-α, α'-diamine (tetraglycidyl-meth-xylenediamine; CAS 63738-22-7).

Alternatively or additionally, it may be advantageous to crosslink the adhesive composition by radio-chemical means. Useful radiation for this purpose includes ultraviolet light (especially when a suitable photoinitiator is added to the formulation, or at least one polymer of the acrylate component contains a comonomer having units of photoinitiation functionality) and / or an electron beam. do.

Radiation-induced crosslinking may be advantageous when some of the monomers used contain functional groups that assist in subsequent radiation-chemical crosslinking. Examples of suitable copolymerizable photoinitiators are, for example, benzoin acrylate and acrylate-functionalized benzophenone derivatives. Monomers that assist crosslinking by electron impacts include, for example, tetrahydrofurfuryl acrylate, N-tert-butylacrylamide, and allyl acrylate.

For chemical and / or physical and / or radiation-induced crosslinking, particular reference is made to the related prior art.

In order to achieve the desired properties of the pressure sensitive adhesive composition, for example to achieve sufficient cohesion of the pressure sensitive adhesive composition, the pressure sensitive adhesive composition is generally crosslinked, which means that the individual macromolecules are bonded to each other by bridging bonds. it means. Crosslinking can be accomplished in different ways. For example, physical, chemical, or thermal crosslinking methods exist.

Crosslinking of a polymer, in particular, refers to a reaction in which several macromolecules, linear or branched, are joined by the formation of bridges between individual macromolecules to provide a somewhat branched network. Bridges are formed, in particular, by the reaction of suitable chemical molecules, called crosslinkers or crosslinker materials, with certain functional groups of macromolecules, for example macromolecules which can be particularly attacked by individual crosslinker molecules. Sites in crosslinker molecules that attack macromolecules are generally referred to as "reactive centers". The crosslinker molecule may react with one and the same crosslinker molecule with two different macromolecules, that is, in particular with at least two reactive centers, or the crosslinker molecule may also have one single crosslinker molecule and also three or more macromolecules with each other. Two macromolecules can be bonded to each other in that they can have more than two reactive centers to bind. Intramolecular reactions may occur as side reactions when one and the same crosslinker molecule attacks one and the same macromolecule having at least two of its reaction centers. In the context of effective crosslinking of the polymer, such side reactions are generally not desired.

It is possible to distinguish the following different types of crosslinkers:

1) Covalent crosslinkers, ie crosslinkers which covalently attack the macromolecules to which they are bound, thus forming a covalent chemical bond between the corresponding reaction center and the attacking site on the macromolecule, ie, in particular a functional group. Useful chemical reactions include in principle all conceivable chemical reactions which form covalent bonds.

2) a coordinating crosslinking agent, ie a crosslinking agent coordinatingly attacking the macromolecule to which it is bound, thus forming a coordinating bond between the corresponding reaction center and the attacking site on the macromolecule, ie in particular the functional group. Useful chemical reactions include in principle all conceivable chemical reactions that form coordination bonds.

The present invention also relates to crosslinked pressure sensitive adhesives which can be obtained by crosslinking the self-adhesive composition layer (SK1) and / or the self-adhesive composition layer (SK2), preferably both layer (SK1) and layer (SK2). It is about a strip.

The self-adhesive composition layer based on the acrylate composition may comprise further components, for example, microballoons, tackifying resins and / or additives. With regard to the type and amount thereof, reference is similarly applicable with regard to the layer of self-adhesive composition based on the vinylaromatic block copolymer composition.

(b.1) Specific practice of self-adhesive composition layers based on acrylate compositions

The adhesive composition of layer (SK1) or layer (SK2), or preferably both layer (SK1) and layer (SK2), is preferred in particularly preferred embodiments of the invention, referred to below as "specific embodiments". Preferably, the crosslinkable adhesive composition comprises the following components:

(a) at least one first base component comprising (a1) and (a2):

(a1) a first polymer component, homopolymer, copolymer, or two or more homopolymers, two or more copolymers, or a mixture of one homopolymer and one or more copolymers, wherein at least one or copolymers of homopolymers At least one of them, in particular all polymers of the base polymer component, have a functional group that exhibits in particular a crosslinkability with the epoxy groups, and

(a2) optionally, further components homogeneously compatible with or soluble in the base polymer component, for example resins, additives, monomer residues, short-chain polymerization products, as by-products and / or impurities,

(b) optionally, a second component comprising the following (b1) and (b2):

(b1) As further polymer components, polymers which are not inherently homogeneously miscible with the base polymer component, in particular polymers having groups which are not crosslinkable, and

(b2) Optionally, further components, such as certain resins or additives, which are not inherently homogeneous miscible with the base polymer component and which are not soluble in such components, wherein component (b2) is a further polymer component ( particularly completely or partially homogeneously miscible with b1),

(c) crosslinking agents, ie

(c1) at least one covalent, in particular epoxy-based, crosslinker, and / or

(c2) at least one coordination crosslinker, and

(d) optionally a solvent or solvent residue.

More particularly, the crosslinkable self-adhesive composition (SK1 and / or SK2) consists of the components (a), (b), (c) and optionally (d).

The first base component (a) may in particular be a polyacrylate component (P) and the second component (b) may in particular be an elastomer component (E) within the meaning of the foregoing.

Useful polymers for the base polymer component (a1) for certain embodiments include those polymers and polymer mixtures that can be crosslinked, in particular, by covalent or coordinating crosslinking agents. These are especially polymers with free acid groups available for crosslinking. Preferred base polymers which can be used are acrylate copolymers, in particular those polymers (copolymers, polymer mixtures) which can be derived up to at least 50% by weight from acrylic monomers. The comonomers chosen for the introduction of crosslinkable groups are copolymerizable monomers with free acid groups, with acrylic acid being particularly preferred. For example, acrylic acid containing acid groups have properties that affect the pressure-sensitive adhesive properties of the pressure-sensitive adhesive composition. If acrylic acid is used, it is preferably used in proportions up to 12.5% by weight, based on the total monomers of the base polymer component. Depending on the amount of crosslinking agent used in each case, the amount of acrylic acid included in the polymer is preferably at least sufficient to have sufficient acid groups to cause an essentially complete reaction of the crosslinking agent.

For some of these, the polyacrylate component (a) of the advantageous pressure sensitive adhesive composition of certain embodiments preferably constitutes a homogeneous phase. Elastomeric component (b) may be intrinsically homogeneous or may itself have intrinsic polyphase as known from microphase-separated block copolymers. In the present context, the polyacrylate component and the elastomer component are selected such that after intimate mixing, these are not inherently miscible at 20 ° C. (ie, typical use temperatures for adhesive compositions). “Inherently miscible” means that the components are not homogeneously compatible with each other at all, or that the components are only partially miscible with each other such that no phase contains a proportion of the second component in the homogeneous mixture, ie, one Or both components can only homogeneously absorb a low proportion of the individual other components, with some miscibility not essential to the invention and not deleterious to the teachings of the invention. In such cases, corresponding components are considered to be "essentially free" of the individual other components in the context of this document.

Accordingly, the advantageous adhesive compositions of certain embodiments are present in at least two phase morphology at least at room temperature (20 ° C.). Very preferably, the polyacrylate component and the elastomer component are not essentially homogeneously miscible within the temperature range of 0 ° C to 50 ° C, even more preferably -30 ° C to 80 ° C.

Each of the polyacrylate component and / or elastomer component may be in the form of a 100% system, ie, based solely on its individual polymer component ((a1) or (b1)), without further addition of resins, additives, and the like. Can be. In a further preferred manner, one or both of these two components as well as the base polymer component are mixed with additional components, for example resins. In one development, the polymer component for the entire adhesive composition, other than the two polymer components (a1) and (b1), does not include any additional components (crosslinking agent and any present in terms of component (c) Independent of solvent / solvent residue (d)).

The polyacrylate component (a) of the advantageous adhesive composition of certain embodiments includes one or more polyacrylate-based polymers that make up the base polymer component (a1).

The polyacrylate-based polymers are, in particular, as monomers (hereinafter referred to as "acrylic monomers"), acrylic esters and / or methacrylic esters, and optionally, at least most, ie in particular 60 weights from their free acids. Polymers that can be derived to a degree above%. Polyacrylates can preferably be obtained by free-radical polymerization. The polyacrylate may optionally contain additional units based on additional non-acrylic copolymerizable monomers. The polyacrylates may be homopolymers and / or copolymers in particular. The term "copolymer" in the context of the present invention refers to copolymers in which the comonomer used in the polymerization is introduced in a purely random manner, and there is a gradient in the comonomer composition and / or local enrichment of the individual types of comonomers in the polymer chain. And copolymers in which the entire block of monomers is present. Alternate comonomer sequences may be considered or.

The polyacrylates can be, for example, linear, branched, star-shaped, or grafted structures, which can be homopolymers or copolymers. Advantageously, the average molecular weight (weight-average MW) of at least one of the polyacrylates of the polyacrylate of the polyacrylate base polymer, and the plurality of polyacrylates, are advantageously present in a dominant proportion of the polyacrylate weight and In particular, when all polyacrylates are present, the average molecular weight ranges from 250,000 g / mol to 10,000,000 g / mol, preferably from 500,000 g / mol to 5,000,000 g / mol.

In a very preferred procedure, the crosslinkers of component (c) of certain embodiments are optionally homogeneously miscible in the base component, after prior dissolution in a suitable solvent.

The covalent crosslinker (component (c1)) used for certain embodiments is preferably glycidylamine. Examples of particularly preferred crosslinkers according to the invention are N, N, N ', N'-tetrakis (2,3-epoxypropyl) cyclohexane-1,3-dimethylamine and N, N, N', N'- Tetrakis (2,3-epoxypropyl) -m-xylene-α, α'-diamine.

It is also advantageously possible to use multifunctional epoxides, in particular epoxycyclohexyl carboxylates, as covalent crosslinkers. Particular mention may be made here of 2,2-bis (hydroxymethyl) propane-1,3-diol or (3,4-epoxycyclohexane) methyl 3,4-epoxycyclohexylcarboxylate as an example herein.

In addition, multifunctional aziridine can also be used according to the invention. One example of these is trimethylolpropane tris (2-methyl-1-aziridinepropionate). The covalent crosslinker used may more preferably be an isocyanate, in particular a polyfunctional isocyanate compound. The polyfunctional isocyanate compounds used are, for example, tolylene diisoisocyanate (TDI), tolylene 2,4-diisoisocyanate dimer, naphthylene 1,5-diisoisocyanate (NDI), tolylene o-di Isoisocyanate (TODI), diphenylmethane diisoisocyanate (MDI), triphenylmethane triisoisocyanate, tris (p-isocyanatophenyl) thiophosphite, polymethylene polyphenyl isocyanate. These may be used alone or in combination of two or more types thereof.

In certain embodiments, according to the invention, at least one covalent crosslinker is used, but it is also possible to use two or more covalent crosslinkers, for example two above-mentioned diamine compounds in combination with one another.

Useful coordinating crosslinkers (component (c2)) for certain embodiments include chelate compounds, in particular multivalent metal chelate compounds. The term "polyvalent metal chelate compound" is understood to mean a compound in which the polyvalent metal is coordinated to one or more organic compounds. The polyvalent metal atoms used are Al (III), Zr (IV), Co (II), Cu (I), Cu (II), Fe (II), Fe (III), Ni (II), V (II) , V (III), V (IV), V (V), Zn (II), In (III), Ca (II), Mg (II), Mn (II), Y (III), Ce (II) Ce (IV), St (II), Ba (II), Mo (II), Mo (IV), Mo (VI), La (III), Sn (II) Sn (IV), Ti (IV), And the like. Among these, Al (III), Zr (IV) and Ti (IV) are preferred.

In certain embodiments the ligand used for the coordinating crosslinker may in principle be any known ligand. However, the atoms used for the coordinating bond of organic compounds may in particular be atoms with free electron pairs, for example oxygen atoms, sulfur atoms, nitrogen atoms, and the like. Organic compounds used may be, for example, alkyl esters, alcohol compounds, carboxylic acid compounds, ether compounds, ketone compounds, and the like. In particular, titanium chelate compounds such as titanium dipropoxide bis (acetylacetonate), titanium dibutoxide bis (octylene glycolate), titanium dipropoxide bis (ethylacetoacetate), titanium dipropoxy Side bis (lactate), titanium dipropoxide bis (triethanol aluminate), titanium di-n-butoxide bis (triethanol aminate), titanium tri-n-butoxide monostearate, butyl titanate dimer, poly (Titanium acetylacetonate), and the like; Aluminum chelate compounds such as aluminum diisopropoxide monoethyl acetate, aluminum di-n-butoxide monomethylacetoacetate, aluminum di-i-butoxide monomethylacetoacetate, aluminum di-n-butoxide mono Ethylacetoacetate, aluminum di-secondary-butoxide monoethylacetoacetate, aluminum triacetylacetonate, aluminum triethylacetoacetonate, aluminum monoacetylacetonate bis (ethylacetoacetonate), and the like, and zirconium chelate compounds, For example, zirconium tetraacetylacetonate, and the like are listed for illustrative purposes. Among these, aluminum triacetylacetonate and aluminum dipropoxide are preferred. These may be used alone or in combination of two or more types thereof.

The covalent crosslinking agent (c1) is, in certain embodiments, preferably 0.015 to 0.04 and preferably 0.02 to 0.035 parts by weight, very preferably 0.03% by weight, based on 100 parts by weight of the base polymer component (a1) Used as

The coordinating crosslinking agent (c2) is used in certain embodiments, preferably in amounts of 0.03 to 0.15 and preferably 0.04 to 0.1 parts by weight, based on 100 parts by weight of the base polymer component (a1).

More preferably, the covalent crosslinker and the coordinating crosslinker are used in certain embodiments in such a way that the coordinating crosslinker is present in molar excess relative to the covalent crosslinker. Within the above-mentioned range, the crosslinking agent is described in detail in a molar ratio of covalent crosslinking agent to coordinating crosslinking agent, that is, a ratio of molar amount (n _cov ) of covalent crosslinking agent used to molar amount (n _coord ) of coordinating crosslinking agent used is from 1: 1.3 to 1 : 4.5; Accordingly, it is preferable to use in a manner in which 1.3 ≦ n _coord / n _cov ≦ 4.5. A very preferred molar ratio of covalent crosslinker to coordinating crosslinker is from 1: 2 to 1: 4.

(b.2) Elastomeric component of a layer of self-adhesive composition based on acrylate composition

As mentioned above, even in the form of certain embodiments thereof, the adhesive composition used according to the present invention may comprise a polyacrylate component or a base polymer, in particular a polymer that is not inherently homogeneously miscible with the elastomer component. For some of these, the elastomer component, which is essentially incompatible with the polyacrylate component, advantageously comprises one or two independently selected synthetic rubbers as the base polymer component.

The synthetic rubber used is preferably at least one vinylaromatic in the form of a block copolymer having the structure AB, ABA, (AB) _n , (AB) _nX or (ABA) _n X, ABX (A'-B ') _n. Block copolymers, where

The A or A ′ blocks are independently polymers formed by the polymerization of at least one vinylaromatic, for example styrene or α-methylstyrene;

The B or B 'blocks are independently polymers formed by polymerization of conjugated dienes having 4 to 18 carbon atoms, and / or isoprene, butadiene, farnesene isomers or mixtures of butadiene and isoprene or butadiene and styrene Polymers formed from mixtures or containing all or part of ethylene, propylene, butylene, and / or isobutylene;

X is a radical of a coupling reagent or initiator;

n is an integer of 2 or more.

More particularly, all synthetic rubbers are block copolymers having the structure as described in detail above. Accordingly, the synthetic rubber may also comprise a mixture of various block copolymers having such a structure.

Accordingly, suitable block copolymers (vinylaromatic block copolymers) include one or more rubber-like blocks B or B '(soft blocks) and one or more glass-shaped blocks A or A' (hard blocks). Particular preference is given to block copolymers having the structure AB, ABA, (AB) ₃ X or (AB) ₄ X, wherein the meaning is applicable to A, B and X. Most preferably, all synthetic rubbers are block copolymers having the structure AB, ABA, (AB) ₃ X or (AB) ₄ X, wherein the meaning is applicable to A, B and X. More particularly, the synthetic rubber comprises a mixture of block copolymers having an AB, ABA, (AB) ₃ X or (AB) ₄ X structure, preferably at least a diblock copolymer AB and / or a triblock copolymer ABA. Mixture.

Also advantageous are mixtures of diblocks of triblock copolymers and (AB) _n or (AB) _n X block copolymers, where n is at least 3.

In some advantageous embodiments, block copolymers that are multi-arm block copolymers are additionally or exclusively used. This is described by the following general formula:

Q _m -Y

Wherein Q represents one arm of the multi-arm block copolymer and m represents the number of arms, where m is an integer of at least 3. Y is, for example, a radical of a multifunctional binding reagent derived from a coupling reagent or a multifunctional initiator. More particularly, each arm Q independently has the formula A ^* -B ^* , wherein A ^* and B ^* in each case, independently of the other cancers, are defined above for A / A 'and B / B'. Are selected such that each A ^* represents a glassy block and B ^* represents a soft block. It will also be understood that it is possible to select the same A ^* and / or the same B ^* for multiple cancer Qs or all cancer Qs.

Blocks A, A 'and A ^* are referred to collectively as A blocks below. Blocks B, B 'and B ^* are correspondingly referred to collectively as B blocks below.

Blocks are generally glassy blocks, each having a glass transition temperature above room temperature (in the context of the present invention room temperature should be understood to mean 20 ° C.). In some advantageous embodiments, the glass transition temperature of the glassy block is at least 40 ° C, preferably at least 60 ° C, even more preferably at least 80 ° C or very preferably at least 100 ° C.

Vinylaromatic block copolymers generally have one or more rubber-like B blocks that also have a glass transition temperature below room temperature (20 ° C.). In some embodiments, the Tg of the soft block is below -30 ° C, or even below -60 ° C.

As well as the inventive and particularly preferred monomers mentioned for the B blocks, further advantageous embodiments include polymerized conjugated dienes, halogenated derivatives of polymerized conjugated dienes, or combinations thereof. In some embodiments, the conjugated diene contains 4 to 18 carbon atoms.

Preferred conjugated dienes as monomers for soft block B are, in particular, butadiene, isoprene, ethylbutadiene, phenylbutadiene, piperylene, pentadiene, hexadiene, ethylhexadiene and dimethylbutadiene, and any desired mixtures of these monomers. It is selected from the group consisting of. The B blocks may also be in the form of homopolymers or copolymers.

Examples of further advantageous conjugated dienes for the B block additionally include ethylbutadiene, phenylbutadiene, piperylene, pentadiene, hexadiene, ethylhexadiene and dimethylbutadiene, wherein the polymerized conjugated diene is homo It may be in the form of a polymer or copolymer.

More preferably, the conjugated diene as monomer for soft block B is selected from butadiene and isoprene. For example, soft block B is a polyisoprene, polybutadiene or a polymer formed from some or all hydrogenated derivatives of one of these two polymers, polybutylene-butadiene, or a mixture of butadiene and isoprene. Most preferably, the B block is polybutadiene.

The proportion of A blocks based on the total block copolymer is preferably on average from 10% to 40% by weight, more preferably from 15% to 33% by weight.

Preferred polymers for the A block are polystyrenes. Preferred polymers for the B block are polybutadiene, polyisoprene, polyfarnesene and some or all hydrogenated derivatives thereof such as polyethylene-butylene, polyethylene-propylene, polyethylene-ethylene-propylene or polybutylene-butadiene or Polyisobutylene. Polybutadiene is very preferred.

Mixtures of different block copolymers can be used. Preference is given to using triblock copolymer ABA and / or diblock copolymer AB.

The block copolymer can be linear, radial or star-shaped (multi-arm).

(b.3) Crosslinking of the self-adhesive composition layer based on the acrylate composition

The layer (SK1), layer (SK2) or preferably both layer (SK1) and layer (SK2) based on the acrylate composition are preferably in crosslinked form in the pressure-sensitive adhesive strip of the present invention. Crosslinking preferably takes place in the form of a layer or film in the pressure sensitive adhesive composition.

The crosslinking reaction can in particular proceed as follows:

In an advantageous procedure, the two materials are applied to the polymer in solution as either a pure material or predissolved in a suitable solvent, after which the polymer is thoroughly mixed with a crosslinking agent, coated on a temporary or permanent carrier, and then suitable conditions Under drying and crosslinking occurs under these conditions.

In an optional procedure that is particularly suitable for highly reactive systems, first, one of the crosslinkers is added to the polymer solution in pure or predissolved form. The second crosslinker is not supplied until immediately before coating, for example through in-line metered addition and subsequent coating and drying to a downstream active or static mixer.

The pot life (processing time) of the coordination crosslinker can be increased by adding the ligands described above to the polymer / crosslinker solution. Excess ligand is then removed during the drying process, only after that, the coordination crosslinker (completely) is reactive.

Drying conditions (temperature and residence time) are very preferably chosen such that not only the solvent is removed but also the crosslinking is completed to a large extent, such that a stable level of crosslinking is achieved, especially at relatively high temperatures. More particularly, the adhesive composition is fully crosslinked.

Crosslinking of the adhesive composition is, according to the present invention, in the case of repeated (eg daily) micro-shear measurements within a period of 48 hours when the adhesive composition is stored at room temperature (20 ° C.) under different standard conditions, Under the conditions specified herein, it is understood that the maximum shear movement “max” in the micro-shear movement test only changes within the accuracy of the test method (eg up to 5% or less).

According to the field of use of the adhesive composition, the detection of complete crosslinking can also be carried out for other temperatures (eg 40 ° C., in particular those temperatures corresponding to the individual use temperatures).

In an advantageous manner, the pressure sensitive adhesive strips of the invention can be used for the joining of components for precision-mechanical, optical, electrical and / or electronic devices, for example in their fabrication, repair or decoration, and the like. Examples of materials used for bonding herein may include plastics, glass, metals, and the like.

carrier

The carrier material optionally used in the pressure-sensitive adhesive strips of the present invention can in principle be any known (permanent) carrier, such as nonwoven scrims, woven fabrics, knitted fabrics, nonwoven fabrics, papers, tissues, and films. have. Films are commonly used, in which case they may be foamed (eg thermoplastic foam) or not foamed. Film carriers are typically formed using film-forming or extrudable polymers which may additionally be uniaxial or biaxially oriented.

The film carrier may have a single layer or multiple layers, preferably a single layer. In addition, the film carrier may have an outer layer, such as a barrier layer, which prevents penetration of components from the adhesive composition into the film, or vice versa. This outer layer may thus also have a barrier property to prevent penetration-diffusion of water vapor and / or oxygen.

The back side of the film carrier may be treated with an anti-adhesive physical treatment or coating.

For the production of film carriers, it is desirable to add additives and additional ingredients that improve the film-forming properties, reduce the tendency of the formation of crystalline segments and / or, where appropriate, selectively improve or otherwise deteriorate the mechanical properties. May be appropriate.

The film carrier optionally present in the pressure sensitive adhesive strip of the present invention may be a non-extensible film carrier or an extensible film carrier.

The use of non-extensible film carriers in the pressure sensitive adhesive strips of the present invention promotes the processability of the resulting pressure sensitive adhesive strips, and more particularly, the die-cutting process can be facilitated. In addition, in the pressure-sensitive adhesive strip of the present invention, the use of a non-extensible film carrier, for example made of polyethylene terephthalate (PET), can result in improved impact resistance compared to the use of stretchable film carriers. The impact resistance of the pressure sensitive adhesive strips of the present invention not only affects some foamed self-adhesive composition (s) but can also be affected by the nature of the film carrier used and its thickness.

The material used for the film of the non-extensible film carrier (T) is preferably polyester, in particular polyethylene terephthalate (PET), polyamide (PA), polyimide (PI) or uniaxial or biaxially stretched polypropylene (PP). More preferably, the non-extensible film carrier consists of polyethylene terephthalate. Likewise, it is also possible, in particular, to use multilayer laminates or coextrusions of the above mentioned materials. Preferably, the non-extensible film carrier has a single layer.

In an advantageous procedure, one or both surfaces of the non-extensible film carrier layer T have been physically and / or chemically pretreated. Such pretreatment can be achieved, for example, by etching and / or corona treatment and / or plasma pretreatment and / or primer treatment, preferably by etching. If both surfaces of the carrier layer have been pretreated, the pretreatment of each surface may be different, or more particularly, the same pretreatment may be provided on both surfaces.

In order to achieve very good results on roughening, trichloroacetic acid (Cl ₃ C-COOH) is used as a reagent for the etching of films in combination with powder compounds, preferably silicon compounds, more preferably [SiO ₂ ] _x. Or trichloroacetic acid. Points of inert compounds are introduced into the surface of the film, in particular PET film, in order to improve the roughness and surface energy in this way.

Corona treatment is a chemical / thermal process for improving the surface tension / surface energy of a polymer substrate. The electrons are greatly accelerated during the high voltage discharge between the two electrodes, which results in ionization of the air. When a plastic substrate is introduced into the path of this accelerated electrode, the resulting accelerated electrode impinges the substrate surface at two to three times the energy required to break molecular bonds at the surface of most substrates. This results in the formation of gaseous reaction products and highly reactive free radicals. These free radicals can react quickly in the presence of oxygen and reaction products and form various chemical functional groups on the substrate surface. The functional groups formed from this oxidation reaction contribute most to the increase in surface energy. Corona treatment can be accomplished with a two-electrode system, or else with a one-electrode system. During corona pretreatment, it is possible to use different process gases such as nitrogen to form a protective gas atmosphere (as well as general air) or to enhance corona pretreatment.

Plasma treatment, ie, low pressure plasma treatment, is a known process for surface pretreatment of adhesive compositions. The plasma results in surface activity in terms of higher reactivity. This causes chemical changes to the surface, and as a result thereof, may affect the properties of the adhesive composition, for example with respect to polar and nonpolar surfaces. This pretreatment essentially involves surface development.

Primer generally refers to a coating or basecoat, in particular having an adhesion-promoting and / or passivation and / or corrosion-inhibiting effect. In the context of the present invention, this is a particularly important adhesion-promoting effect. Adhesion-promoting primers, also often referred to as adhesion promoters, are in many cases known in the form of articles or from the technical literature.

Suitable non-extensible film carriers are available under the Hostaphan® RNK brand name. This film is highly transparent, biaxially stretched, and consists of four coextruded layers.

The tensile strength of the non-extensible film carrier is, according to the invention, preferably in the longitudinal direction, preferably above 100 N / mm 2, more preferably above 150 N / mm 2, even more preferably above 180 N / mm 2, and In particular, greater than 200 N / mm 2, for example greater than 250 N / mm 2, and in the transverse direction, preferably greater than 100 N / mm 2, more preferably greater than 150 N / mm 2, even more preferably 180 N / mm 2 Greater than, and in particular, greater than 200 N / mm 2, for example greater than 250 N / mm 2 (values are each reported in connection with test method R1 specified below). The film carrier is important for determining the tensile strength of the pressure sensitive adhesive strip. Preferably, the pressure sensitive adhesive strip has the same value for the tensile strength and the film carrier used.

The elastic modulus of the non-extensible film carrier is preferably greater than 0.5 GPa, more preferably greater than 1 GPa and especially greater than 2.5 GPa in both the longitudinal and transverse directions.

When stretchable film carriers are used in the pressure sensitive adhesive strips of the present invention, the stretchability of the film carriers is typically sufficient to ensure detachment of the pressure sensitive adhesive strip through stretching essentially at the bonding surface. The stretchable film carrier is preferably a carrier having an elongation at break of at least 500%, in particular at least 800%, and optionally greater than 50% elasticity. Preferably, the film carrier has a specified elongation at break and / or specified elasticity in both the longitudinal and transverse directions. The film carrier used may be, for example, a very extensible film. Examples of stretchable film carriers which can be used advantageously are embodiments from WO 2011/124782 A1, DE 10 2012 223 670 A1, WO 2009/114683 A1, WO 2010/077541 A1, WO 2010/078396 A1 to be. Preferably, the tensile strength of the extensible carrier material is adjusted such that the pressure-sensitive adhesive strip can be detached from the adhesive bond again by stretching and resealably in a residue-free and non-destructive manner.

In a preferred embodiment of the stretchable film carrier, polyolefins are used. Preferred polyolefins are prepared from ethylene, propylene, butylene and / or hexylene, where in each case it is possible to polymerize pure monomers or copolymerize mixtures of the monomers mentioned. Through the polymerization process and by the choice of monomer, it is possible to control the physical and mechanical properties of the polymer film, for example to control the softening temperature and / or elongation at break. Polyethylene, in particular polyethylene foam, is particularly preferred.

It is also advantageously possible to use polyurethane as starting material for the extensible film carrier. Polyurethanes are typically chemically and / or physically crosslinked polycondensates formed from polyols and isocyanates. According to the properties and the proportions of use of the individual components, stretchable materials can be obtained which can be used advantageously in the context of the present invention. Raw materials available to the formulator for this purpose are described, for example, in EP 0 894 841 B1 and EP 1 308 492 B1. Those skilled in the art will recognize additional raw materials capable of forming the stretchable film carrier of the present invention. Polyurethane foams are particularly preferred.

It is also advantageous to use rubber-based materials in stretchable film carriers to achieve stretchability. As starting materials for stretchable film carriers, rubbers or synthetic rubbers or blends produced therefrom, natural rubbers, in accordance with the desired levels and viscosities, are in principle any available product, for example crepe, RSS, ADS, Can be selected from TSR or CV type, the synthetic rubber (s) being randomly copolymerized styrene-butadiene rubber (SBR), styrene block copolymer (SBC), butadiene rubber (BR), synthetic polyisoprene (IR), butyl Rubber (IIR), halogenated butyl rubber (XIIR), ethylene-vinyl acetate copolymers (EVA) and polyurethanes and / or blends thereof.

Particularly advantageously usable materials for stretchable film carriers are block copolymers. Individual polymer blocks herein are covalently bonded to each other. Block bonds may be in linear form or else star-shaped or graft copolymer variants. One example of a block copolymer which can advantageously be used is a linear triblock copolymer, the two end blocks of which have a softening temperature of at least 40 ° C., preferably at least 70 ° C., the intermediate block of which is at most 0 ° C., preferably , Has a softening temperature of up to -30 ° C. Higher order block copolymers, such as tetrablock copolymers, can likewise be used. Each of the at least two polymer blocks of the same or different class present in the block copolymer has a softening temperature of at least 40 ° C., preferably at least 70 ° C., and a softening temperature of 0 ° C. or less, preferably -30 ° C. or less. It is important to be separated from each other in the polymer chain by at least one polymer block. Examples of polymer blocks are polyethers such as polyethylene glycol, polypropylene glycol or polytetrahydrofuran, polydienes such as polybutadiene or polyisoprene, hydrogenated polydienes such as polyethylene-butylene Or polymer blocks of polyethylene-propylene, polyester, for example polyethylene terephthalate, polybutanediol adipate or polyhexanediol adipate, polycarbonate, polycaprolactone, vinylaromatic monomers, for example polystyrene or poly- [α] -methylstyrene, polyalkyl vinyl ethers and polyvinyl acetates. Corresponding softening temperatures are known to those skilled in the art. Alternatively, those skilled in the art can, for example, see Polymer Handbook [J. Brandrup, E. H. Immergut, E. A. Grulke (eds.), Polymer Handbook, 4th ed. 1999, Wiley, New York. The polymer block may be formed from the copolymer.

In particular, when the self-adhesive composition layer in the pressure-sensitive adhesive strip of the present invention is based on vinylaromatic block copolymers such as styrene block copolymers, the extensible film carrier is preferably a polyvinylaromatic-polydiene block copolymer, In particular, they are based on polyvinylaromatic-polybutadiene block copolymers and, typically, tackifying resins. Such film carriers achieve impressive results, in particular due to the low stripping force, which enables easy resorption of the pressure sensitive adhesive strip, and a low tendency to tear upon redeposition of the pressure sensitive adhesive strip.

Further contemplated stretchable film carriers are foams in sheet form (eg polyethylene or polyurethane).

In addition, polyacrylate cores are contemplated as stretchable film carriers. According to the invention, these are not foamed.

In order to better fix the self-adhesive composition on the extensible film carrier, the film carrier may be pretreated by known means such as corona, plasma or flame. The use of primers is also possible. Ideally, however, it is possible to omit the preprocessing.

Preferred Configuration of Pressure Sensitive Adhesive Strip

Advantageously, the outer exposed surface of the outer adhesive composition layer of the pressure sensitive adhesive strip of the present invention may be provided with an anti-stick material, such as a release paper or a release film, also specifically called a liner as a temporary carrier. The liner may also be a material having an anti-stick coating on both sides, for example a double sided siliconized material. The liner (release paper, release film) is not part of the pressure sensitive adhesive strip, but only an aid for its production and / or storage and / or for further processing by die-cutting. Also, the liner is not firmly bonded to the adhesive layer, as opposed to the adhesive tape carrier.

A typical final form of the pressure sensitive adhesive strip of the invention is an adhesive tape roll, in particular the pressure sensitive adhesive strip in the form of a sheet can be formed in the form of a roll, that is, for example, an adhesive strip as obtained in the form of a die cut and Archimedes can be wound in a spiral.

Preferably, all the layers have an essentially cuboid shape. More preferably, all the layers are bonded to each other over the entire area. Such bonding can be optimized by pretreatment of the film surface.

The general expression “adhesive strip” (pressure sensitive adhesive strip), or synonymously “adhesive tape” (pressure sensitive adhesive tape), in the context of the present invention, refers to a film or film section extending in two dimensions, an extended length and a limited width. Tapes, tape sections, etc., and finally, also all sheet-like structures such as die-cut parts or labels.

Accordingly, the pressure sensitive adhesive strip has a longitudinal size (x direction) and a lateral size (y direction). The pressure sensitive adhesive strip also has a thickness (z direction) running perpendicular to the two sizes, and the lateral size and the longitudinal size are many times larger than the thickness. The thickness is very substantially the same, preferably exactly the same, over the entire area size of the pressure-sensitive adhesive strip determined by its length and width.

The pressure-sensitive adhesive strip of the present invention has a sheet form, in particular. A sheet is understood to mean an object, whose length (size in the x direction) is many times larger than its width (size in the y direction) and the width over the entire length remains approximately and preferably exactly the same. .

The use of non-extensible film carriers in the pressure sensitive adhesive strips of the present invention results in advantageous ease of use of the pressure sensitive adhesive strips, in particular comprising fine pore die-cut parts. Non-extensible film carriers usable in the pressure-sensitive adhesive strips of the present invention cause significant stiffness of the die-cut parts so that the die-cutting process and the alignment of the die-cut parts are simplified. Die-cut parts formed from the pressure-sensitive adhesive strips of the present invention and having non-extensible film carriers can, in particular, have outer die-cut edges and inner openings, which thus have a frame shape. Here, it is possible for the individual components to have a width of less than 5 mm, or less than 2.5 mm, or even less than 1 mm.

The use of stretchable film carriers in the pressure sensitive adhesive strips of the present invention allows for other advantageous product configurations. In particular, pressure-sensitive adhesive strips can be obtained which can be detached in a non-destructive manner from bonding under the residue-free and by stretching.

According to the invention, the film carrier layer (T), the self-adhesive composition layer (SK1) and optionally the self-adhesive composition layer (which is essentially residue-free at the bonding surface by stretching and re-desorbable in a non-destructive manner) Particular preference is given to pressure-sensitive adhesive strips comprising SK2), wherein the layers SK1 and / or SK2, preferably both layers SK1 and SK2 are

Contain at least one type of polyvinylaromatic-polydiene block copolymer, preferably an elastomer portion (a1) based on polyvinylaromatic-polybutadiene block copolymer, wherein the elastomeric portion (a1) is at least 90 Consisting of weight percent polyvinylaromatic-polydiene block copolymers, wherein the size of the polyvinylaromatic in the polyvinylaromatic-polydiene block copolymer is at least 12% by weight and at most 35% by weight, and preferably at least 20% by weight. % And up to 32% by weight, the weight ratio of the elastomeric part a1 based on the corresponding layer (SK1 or SK2) is at least 40% by weight and at most 55% by weight, and preferably at least 45% by weight,

A tackifying resin portion (a2) comprising at least one class of tackifying resin, wherein the tackifying resin portion (a2) is at least 90% by weight, preferably at least 95% by weight Consisting of a hydrocarbon resin that is inherently miscible with the diene block and not inherently miscible with the polyvinylaromatic block, wherein the proportion of the tackifying resin portion (a2) is at least 40 based on the corresponding layer (SK1 or SK2) Weight percent and up to 60 weight percent,

Optionally contains a soft resin part (a3), wherein the soft resin part (a3) is from 0 to 5% by weight, based on the corresponding layer (SK1 or SK2),

Optionally contains further additives (a4),

Here, preferably, the unfoamed film carrier layer T

An elastomeric part (b1) based on at least one class of polyvinylaromatic-polydiene block copolymers, wherein the elastomeric part (b1) is at least 90% by weight polyvinylaromatic-polydiene block copolymer , Preferably, polyvinylaromatic-polybutadiene block copolymers and / or polyvinylaromatic-polyisoprene block copolymers, wherein the polyvinylaromatic content in the polyvinylaromatic-polydiene block copolymer is at least 20% by weight and At most 45% by weight, preferably at least 25% by weight and at most 35% by weight, and the proportion of at least one triblock copolymer or linear or radial multiblock copolymer in the elastomer portion is at least 80% by weight, preferably at least 90 % By weight, wherein the molar mass (maximum molar mass MP by GPC) of the triblock copolymer or multiblock copolymer is at least 85,000 g / mol, the proportion of the diblock copolymer is less than 20% by weight, preferably up to 10% by weight and in particular 0% by weight of the elastomer (b1) based on the formulation of the film carrier layer (T) The proportion is at least 40% by weight and at most 60% by weight, preferably at least 45% by weight and at most 55% by weight,

A tackifying resin portion (b2) comprising at least one class of tackifying resin, wherein the tackifying resin portion (b2) is at least 90% by weight, preferably at least 95% by weight, Consisting of a hydrocarbon resin that is inherently miscible with the polydiene block and not inherently miscible with the polyvinylaromatic block, the proportion of the tackifying resin portion (b2) being based on the overall formulation of the film carrier layer (T) , At least 40% by weight and up to 60% by weight,

Optionally contains a soft resin portion (b3), wherein the soft resin component (b3) is from 0% to 5% by weight, based on the total formulation of the film carrier layer (T),

Optionally contains further additives (b4),

Here, the density of the film carrier layer T is at least 950 g / cm 3.

Preferably, the tackifying resin portion a2 and the tackifying resin portion b2 are chemically identical.

Preparation of Pressure Sensitive Adhesive Strips

The production and processing of the self-adhesive compositions SK1 and SK2 usable according to the invention can be carried out from solution or from melt (hotmelt). Application of the self-adhesive compositions SK1 and SK2 usable according to the invention to the carrier layer can be carried out by direct coating or by lamination, in particular hot lamination.

In a conventional method for preparing the self-adhesive composition layer of the present invention, all components of the adhesive composition are dissolved in a solvent mixture, for example benzine / toluene / acetone. The microballoons are, for example, converted into slurries in benzine and stirred into the dissolved adhesive composition. To this end, it is possible in principle to use known compounding and stirring units, which must be ensured that the microballoons do not yet expand during the mixing process. As soon as the microballoons are homogeneously distributed in solution, the adhesive composition can be coated, for which the coating system of the prior art can be used again. For example, coating may be accomplished by doctor blades on conventional PET liners. In the next step, the coated adhesive composition is dried, for example at 100 ° C. for 15 minutes, and optionally crosslinked. There is no random expansion of the microballoons in any of the above steps. After drying, the adhesive layer is covered with a second ply or carrier of the PET liner and partially foamed in an oven, for example at 130 ° C. to 180 ° C., in order to create a particularly smooth surface, in particular two liners Between or between the liner and the carrier. Some foaming is achieved by timely cooling at room temperature (20 ° C.), for example, to establish the desired degree of foaming.

If the dried adhesive layer is foamed between two liners, the result is the pressure sensitive adhesive strip of the present invention consisting of a self-adhesive layer. When the self-adhesive layer is foamed between the liner and the carrier, the result is the pressure-sensitive adhesive strip of the present invention in the form of a single-sided adhesive tape.

Alternatively, before foaming the dried self-adhesive layer localized between the liner and the carrier, the unfoamed 3 consists of an inner carrier and two self-adhesive layers in direct contact with the carrier and provided with a liner on its outer surface. To provide a layer composite, it is possible to laminate a second, similarly dried microballoon-containing self-adhesive layer applied to the liner from the dried self-adhesive layer onto the opposite surface of the carrier. Such a three layer composite may also be provided by directly or simultaneously coating the carrier (T) with an unfoamed self-adhesive composition containing microballoons, after which the self-adhesive composition layer is for example at 100 ° C. 15 After drying for minutes, it is covered with a liner. After drying, the adhesive layer is partially foamed in the oven (see above) in a suitable temperature / time window to produce a particularly smooth surface, in particular covered between two liners. The result is the pressure-sensitive adhesive strip of the present invention in the form of a double-sided adhesive tape with a carrier.

The surface of some expanded self-adhesive composition layers prepared by the solvent method typically has _a roughness Ra of less than 15 μm, preferably less than 10 μm, more preferably less than 5 μm, most preferably less than 3 μm. . The surface roughness (R _a) constitutes an average absolute distance from the center line of the roughness profile within an industry standard unit for the final quality of the surface treatment, the average height of roughness, in particular rating range. In other words, R _a is the arithmetic mean roughness, that is, the arithmetic mean of all profile values in the roughness profile. In the present application, R _a is measured by laser triangulation. Low surface roughness has certain advantages that result in improved impact resistance of the pressure sensitive adhesive strip. The result is usually improved binding force.

The particularly low surface roughness (R _a ) of the partially expanded self-adhesive composition layer, typically less than 3 μm, preferably less than 2 μm, and in particular less than 1 μm, surprisingly suggests that the self-adhesive composition layer is a single layer of microballoons. In the case of a layer, a suitable degree of foaming can be produced by the solvent method once selected. The self-adhesive composition layer comprises a single layer of microballoons when there are no multiple microballoon layers on top of each other in the self-adhesive composition layer. Preferably, the microballoons in the self-adhesive composition layer are present on approximately one side (FIGS. 5A and 6A). Such a monolayer may be provided such that, for example, the layer of self-adhesive composition has a coat weight measured in g / m 2, which is smaller than the average diameter of the voids formed by the microballoons in the layer of self-adhesive composition. Can be. In the context of the present application, the coat weight is based on the dry weight of the adhesive mixture applied. Preferably, the ratio of the coat weight (g / m 2) of the pressure-sensitive adhesive layer to the average diameter (μm) of the voids formed by the microballoons is 0.6 to 0.9, more preferably 0.7 to 0.8. By suitable choice and combination of adhesive composition, liner and foaming process, and also due to the particle size distribution in the adhesive tape with a smooth product surface, it is possible to maintain larger microballoons likewise present in the self-adhesive composition layer. Foaming between two liners facilitates, for example, the creation of pressure-sensitive adhesive strips having a particularly smooth surface. Accordingly, the present invention is low at the same time thin and the surface roughness (R _a), therefore it is possible to provide a pressure-sensitive adhesive strip having a high bonding strength and impact resistance. Pressure-sensitive adhesive strips of this kind are particularly important for the adhesion of electronic components and such components, which in particular have little space available for adhesion, such as mobile devices, for example mobile phones.

In contrast, inadequate foaming parameters can result in microballoons, in particular protruding from the adhesive composition, resulting in a rough surface. In particular, the self-adhesive composition when the thickness of the thin layer, in particular a high level of foam, such as fully expanded microballoons this is protruding from the adhesive layer after firing may have a roughness (R _a) an increased effect. This phenomenon can be prevented by some degree of foaming which is obvious to those skilled in the art, in particular taking into account each coat weight and each type of microballoon by only a few experiments.

The chosen expansion temperature is higher than the drying temperature, especially to avoid expansion of the microballoons during the drying process.

Alternatively, the self-adhesive composition layers SK1 and SK2 can be prepared from the melt. The degree of foaming is typically established through the temperature and residence time of the adhesive mixture in the extruder.

Accordingly, the present invention is, for example, a process for producing a layer of the self-adhesive composition of the present invention,

_The components for formation of the adhesive composition, such as polymers, resins or fillers and unexpanded microballoons, are mixed in a first mixing unit, heated to an expansion temperature,

_● and micro balloon is partially inflated during mixing,

_The adhesive composition mixture with the partially expanded microballoon is formed into a layer with a roll applicator,

_● and with the partially expanded microballoons and a step that is applied to the carrier or the release material in the form of a sheet, optionally the adhesive composition mixture.

The present invention provides a process for producing a self-adhesive composition layer of the present invention,

_The components for formation of the adhesive composition, such as polymers, resins or fillers and unexpanded microballoons, are mixed in a first mixing unit, heated to an expansion temperature under elevated pressure,

_● When microballoons are discharged from the mixing unit is partially expanded,

_The adhesive composition mixture with the partially expanded microballoon is formed into a layer with a roll applicator,

_The process further comprises the application of the adhesive composition mixture, optionally together with the partially expanded microballoons, to the carrier or release material in the form of a sheet.

The present invention is similarly a process for producing the self-adhesive composition layer of the present invention,

_The components for the formation of an adhesive composition such as a polymer, resin or filler together with the unexpanded microballoons are mixed in a first mixing unit under elevated pressure and heated to a temperature lower than the expansion temperature of the microballoons,

_● moves to a particularly homogeneous adhesive composition to the second mixing unit mixture from the first mixing unit, and heated to the expansion temperature,

_● When microballoons in the second mixing unit, or the second discharge from the mixing unit is partially expanded,

_The adhesive composition mixture with the partially expanded microballoon is formed into a layer with a roll applicator,

_{A process wherein the} adhesive composition mixture together with a partially expanded microballoon is optionally applied to a carrier or release material in sheet form.

The present invention is similarly a process for producing the self-adhesive composition layer of the present invention,

_The components for the formation of an adhesive composition, such as a polymer, resin or filler, are mixed in a first mixing unit,

_● is introduced first it is that the, in particular a homogeneous mixture of the adhesive composition from the mixing unit move to the second unit, which is also the non-expanded microballoons,

_● When microballoons in the second unit, or exiting the second unit is partially expanded,

_The adhesive composition mixture with the partially expanded microballoon is formed into a layer with a roll applicator,

_{A process wherein the} adhesive composition mixture together with a partially expanded microballoon is optionally applied to a carrier or release material in sheet form.

Accordingly, the hotmelt process for producing the self-adhesive composition layer of the present invention described is a process in which a pressure-sensitive adhesive strip, ie a transfer tape, each composed of a single self-adhesive composition layer can be provided. Optionally, the self-adhesive composition layer may be covered here with a release material in the form of a sheet, ie in the form of a liner. Preferably, the self-adhesive composition layer is covered with a liner on both sides.

In the described process, when the resulting self-adhesive composition layer is applied to a carrier material in the form of a sheet, ie a film carrier, the result is a single-sided adhesive tape. Optionally, it is thus possible to cover the opposing surface of the self-adhesive composition layer from the carrier layer T with a release material in the form of a sheet, ie a liner.

In a three layer system consisting of a carrier layer (T), a self-adhesive composition layer and a liner, an additional self-adhesive composition layer is thus applied to the opposite surface of the carrier layer (T) from the self-adhesive composition layer, The result is a double sided adhesive tape of the present invention with a carrier. Optionally, it is thus possible to cover the opposing surface of the self-adhesive composition layer from the carrier layer T with a release material in the form of a sheet, ie a liner.

In general, it is not necessary to degas some foamed composition with microballoons before coating to obtain a uniform and continuous coating. Partially expanded microballoons displace air entrained in the adhesive composition during compounding. Nevertheless, for high throughput, it is desirable to degas the composition prior to coating to obtain a homogeneous feed of the composition in the roll gap. Degassing is ideally performed immediately upstream of the roll applicator with a pressure difference between the mixing temperature and the ambient pressure of at least 200 mbar.

In addition, the following cases are advantageous:

_● a first mixing unit is a continuous unit, in particular a planetary roll extruder, a twin-screw extruder or the extruder pin,

_● a first mixing unit is a batch-type unit unit, in particular Z kneader or an internal mixer,

_● a second mixing unit is a planetary roll extruder, a single screw extruder or twin-screw extruder or the extruder pin, and / or,

_The molding unit in which the adhesive composition is molded together with the partially expanded microballoon to provide a layer is a gap formed by a calender, a roll applicator or a roll and a fixed doctor.

The hotmelt process of the present invention allows solvent-free processing of all previously known components of the adhesive composition and of the components described in the literature, in particular of the self-adhesive component.

Many units are known for the continuous production and processing of solvent-free polymer systems. Generally, screw machines such as single and twin screw extruders with different processing lengths and different equipment are used. Alternatively, a wide variety of different types of continuous kneaders are used for this operation, including, for example, combinations of kneaders and screw machines, or else planetary roller extruders.

Planetary roll extruders have been known for some time and were first used in the processing of thermoplastics, for example PVC, where they were mainly used for the filling of downstream units such as calender or roll systems. The advantages of high surface regeneration, short dwell time and narrow dwell time spectrum for materials and heat exchange, which can quickly and effectively remove the energy entering through friction, especially require a mode of operation with excellent temperature control. The range of use has recently been extended to the foundry process.

Planetary roll extruders exist in various designs and sizes depending on the manufacturer. According to the desired throughput, the diameter of the roll cylinder is typically 70 mm to 400 mm.

The planetary roll extruder generally has a filling section and a compounding section.

The filling section consists of a conveying screw in which all solid components are continuously metered. The feed screw then transfers the material into the compounding section. The area of the filling section with the screw is preferably cooled to avoid caulking of material on the screw. However, there are also embodiments without screw sections, where the material is applied directly between the central spindle and the planetary spindle. However, this is not critical to the efficacy of the process of the present invention.

The compounding section consists of several planetary spindles and a drive center spindle that rotates about a central spindle in one or more roll cylinders with internal helical gearing. The speed of the central spindle and thus the peripheral speed of the planetary spindle can vary and is therefore an important parameter for the control of the compounding process.

The material is circulated between the central spindle and the planetary spindle, ie between the planetary spindle and the helical gearing of the roll section, so that the material is dispersed under the influence of shear energy and external temperature control to provide a homogeneous compound.

The number of planetary spindles rotating in each roll cylinder can be varied and thus adapted to the needs of the process. The number of spindles affects the free volume in the planetary roll extruder and the residence time of the material in the process and further determines the size of the area for heat and mass exchange. The number of planetary spindles influences the compounding result through the shear energy introduced. Given a constant roll cylinder diameter, larger numbers of spindles can be used to achieve better homogenization and dispersion performance or to increase product throughput.

The maximum number of planetary spindles that can be installed between the central spindle and the roll cylinder depends on the diameter of the roll cylinder and the diameter of the planetary spindle used. When using larger roll diameters or smaller diameters for planetary spindles as needed to achieve throughput at production scale, roll cylinders can be equipped with a larger number of planetary spindles. Typically, for roll diameters of D = 70 mm, up to seven planetary spindles are used, whereas for roll diameters of D = 200 mm, for example ten planetary spindles can be used, D = 400 mm For a roll diameter of, for example, 24 planetary spindles can be used.

According to the present invention, it is proposed that the coating of some foamed adhesive composition is carried out in a solvent-free manner using a multiroll applicator system. These may be applicator systems consisting of at least two rolls having at least one roll gap and up to five rolls having three roll gaps.

In addition, a coating system such as calender (I, F, L calender) may be considered such that some foamed adhesive composition is molded to the desired thickness as it passes through one or more roll gaps.

Preferred four-roll applicators are formed by a metering roll, a doctor roll that determines the layer thickness on the carrier material and is arranged parallel to the metering roll, and a transfer roll disposed below the metering roll. In a lay-on roll forming a second roll gap with the transfer roll, the composition and material in sheet form are brought together.

In order to improve the transfer properties of the composition layer molded from one roll to another roll, anti-stick finishing rolls or pattern rolls can also be used. In order to produce an adhesive film of sufficiently precise shape, the peripheral speed of the roll may be different.

Depending on the nature of the carrier material in the form of the sheet to be coated, the coating can be carried out in a co-rotating or counter-rotating process.

In addition, the forming system may be formed by a gap formed between the roll and the fixed doctor. The fixed doctor may be a knife-type doctor, or it may be a fixed (semi-) roll otherwise.

When forming the adhesive composition mixture to provide a layer with the roll applicator, the partially expanded microballoons are pushed back into the polymer matrix of the adhesive composition, thus creating a smooth surface. Accordingly, the decrease in the bonding force due to the microballoons can be significantly reduced. The surface of the resulting self-adhesive composition layer typically has _a roughness Ra _a of less than 15 μm, more preferably less than 10 μm and most preferably less than 3 μm.

It has been found useful to adjust the temperature of the roll to the expansion temperature of the microballoons. Ideally, the roll temperature of the first roll is higher than the expansion temperature of the microballoons to enable further foaming of the microballoons with the desired degree of foaming without breaking the microballoons. The final roll should have a temperature below the expansion temperature so that the microballoon shell can solidify and form a smooth surface of the present invention.

Alternatively, the roll temperature of all rolls can be at or below the expansion temperature of the microballoons, so that the microballoon shells can solidify at an early stage, which minimizes further foaming. Even in this procedure, the smooth surface of the present invention is formed.

The transfer roll may have a temperature above the foaming temperature of the selected microballoon type while the receiving rolls have a temperature below the foaming temperature to prevent uncontrolled foaming, and all rolls may be individually set to a temperature of 30 to 220 ° C. In this way, it has been found to be particularly advantageous to select a temperature regime for the individual rolls so that controlled further foaming can occur in some cases.

drawing

With reference to the drawings described below, particularly advantageous embodiments of the present invention will be described in detail without any intention of unnecessarily limiting the present invention.

1 shows a schematic structure of a three-layer pressure sensitive adhesive strip of the invention consisting of three layers 1, 2, 3 in cross section.

The strip comprises an extensible film carrier 1 (layer T), for example based on vinylaromatic block copolymers. Alternatively, the strip comprises an unextensible film carrier 1 (layer T), for example in the form of a transparent PET film. On the upper and lower surfaces of the film carrier 1 are two outer partially foamed self-adhesive composition layers 2, 3 (layers SK1 and SK2), preferably based on vinylaromatic block copolymers, respectively. exist. The self-adhesive composition layers 2, 3 (layers SK1 and SK2) are also covered by the liners 4, 5 on each side in the exemplary embodiment shown.

2 shows a schematic structure of the one-layer pressure-sensitive adhesive strip of the present invention consisting of one layer 2 in cross section.

The strip preferably comprises some foamed self-adhesive composition layer 2 (layer SK1) based on vinylaromatic block copolymer. The self-adhesive composition layer 2 (layer SK1) is covered by liners 4, 5 on each side in the exemplary embodiment shown.

FIG. 3A is a reflected light microscope of some foamed self-adhesive composition layer (SK1) of the present invention, based on vinylaromatic block copolymer (Microballoon type: Expancel 920 DU20, degree of expansion: 44%) from Example 4. An image is shown.

FIG. 3B is a reflected light microscope of some foamed self-adhesive composition layer (SK1) of the present invention, based on vinylaromatic block copolymer (Microballoon type: Expancel 920 DU20, degree of expansion: 49%) from Example 5. An image is shown.

FIG. 3C shows reflected light of an unfoamed self-adhesive composition layer based on vinylaromatic block copolymer (microballoon type: Expancel 920 DU20, degree of expansion: 0%) from Comparative Example 6 (not the present invention). The microscope image is shown.

FIG. 3D shows reflected light of a fully foamed self-adhesive composition layer based on vinylaromatic block copolymer (microballoon type: Expancel 920 DU20, degree of expansion: 100%) from Comparative Example 7 (not present invention). The microscope image is shown.

FIG. 3E shows an overexpanded self-adhesive composition layer based on vinylaromatic block copolymer (microballoon type: Expancel 920 DU20, degree of expansion: -88%) from Comparative Example 8 (not present) The reflected light microscope image is shown.

4A is a reflected light microscope of some foamed self-adhesive composition layer (SK1) of the present invention, based on vinylaromatic block copolymer (Microballoon type: Expancel 920 DU40, degree of expansion: 29%) from Example 9 An image is shown.

4B is a reflected light microscope of some foamed self-adhesive composition layer (SK1) of the present invention, based on vinylaromatic block copolymer (Microballoon type: Expancel 920 DU40, degree of expansion: 69%) from Example 10. An image is shown.

4C shows reflected light of an unfoamed self-adhesive composition layer based on vinylaromatic block copolymer (microballoon type: Expancel 920 DU40, degree of expansion: 0%) from Comparative Example 11 (not the present invention). The microscope image is shown.

FIG. 4D shows reflected light of a fully foamed self-adhesive composition layer based on vinylaromatic block copolymer (microballoon type: Expancel 920 DU40, degree of expansion: 100%) from Comparative Example 12 (not present) The microscope image is shown.

FIG. 4E shows an overexpanded self-adhesive composition layer based on vinylaromatic block copolymer (microballoon type: Expancel 920 DU40, degree of expansion: -12%) from Comparative Example 13 (not present) The reflected light microscope image is shown.

FIG. 5A is a portion of the present invention based on vinylaromatic block copolymer (Microballoon type: Expancel 920 DU20, degree of expansion: 73%, coat weight: 10 g / m 2, thickness: 13 μm) from Example 17. Scanning electron microscopy image of freeze destruction of the foamed self-adhesive composition layer (SK1) is shown. Microballoons exist here as a single layer. The surface of the layer SK1 is smooth. The monolayer of microballoons is also illustrated by a diagram of the self-adhesive composition layer SK1 in FIG. 5B.

FIG. 6A is a portion of the present invention based on vinylaromatic block copolymer (Microballoon type: Expancel 920 DU20, degree of expansion: 73%, coat weight: 10 g / m 2, thickness: 13 μm) from Example 17. Scanning electron microscopy image of freeze destruction of the foamed self-adhesive composition layer (SK1) is shown. Likewise, microballoons exist here as a single layer. It is noted that as a result of the particle size distribution the larger microballoons present in the adhesive composition layer are also retained in the adhesive tape with a smooth product surface. The single layer of microballoons is also illustrated by a diagram of the self-adhesive composition layer SK1 in FIG. 6B.

The invention is illustrated in detail by the following several examples. With reference to the embodiments described below, particularly advantageous implementation of the invention will now be described in detail without any intention of unnecessarily limiting the invention.

Example

A description follows for the preparation of the pressure-sensitive adhesive strip of the invention, each consisting of a single self-adhesive composition layer (SK1) based on some foamed adhesive composition with microballoons (MB). There are variations in base adhesive composition, microballoon type and content, and coat weight. Coat weight is based on the dry weight of the adhesive solution applied here.

Example 1:

Pressure-sensitive adhesive strips of the invention were prepared based on styrene block copolymer (SBC) compositions.

To this end, first, a 40 wt% adhesive solution in benzine / toluene / acetone is prepared from 50.0 wt% Kraton D1102AS, 45.0 wt% Dercolyte A115, 4.5 wt% Wingtack 10 and 0.5 wt% Irganox 1010 Aging Stabilizer (Also called adhesive solution 1). The weight ratio of dissolved components is based on the dry weight of the resulting solution, respectively. The above components of the adhesive composition are characterized as follows:

Kraton D1102AS: Styrene-butadiene-styrene triblock copolymer from Kraton Polymers with 17 wt% diblock and block polystyrene content: 30 wt%

Dercolyte A115: solid α-pinene tackifying resin with ring and ball softening temperature of 115 ° C. and DACP of 35 ° C.

Wingtack 10: Liquid Hydrocarbon Resin from Cray Valley

Irganox 1010: Pentaerythritol tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate) from BASF SE

The solution was then mixed with 3.3% by weight of unexpanded Expancel 920 DU20 microballoons using microballoons in the form of a slurry in benzene. In the examples, the weight ratio of the microballoons is based on the dry weight of the solution to which they are added (ie the dry weight of the solution used is fixed at 100%). The resulting mixture is subsequently evaporated at 100 ° C. for 15 minutes, followed by drying the composition layer and then on a PET liner provided with a silicone release layer in a layer thickness such that the coat weight is 75 g / m ² . It was coated directly onto the coating.

Thereafter, after laminating the second PET liner on the free surface of the resulting dried adhesive composition layer, the adhesive composition layer was partially foamed between two liners in an oven at 140 ° C. for 30 seconds. Room temperature then cooled in (20 ℃), (without the PET liner) adhesive composition layer is also 76% of the foam and had a 111 ㎛ thickness, 674 ㎏ / ㎥ density and less than 10 ㎛ surface roughness (R _a) of the . By die-cutting, pressure sensitive adhesive strips of the desired dimensions were obtained.

Comparative Examples 2 and 3:

Comparative Example 2 was a pressure sensitive adhesive strip from Example 1 but before foaming. The adhesive composition layer (without the PET liners) had a less than 75 ㎛ of thickness, density and 10 ㎛ of 1000 ㎏ / ㎥ surface roughness (R _a).

Comparative Example 3 was obtained from Example 1 except that the preparation included full expansion of the adhesive composition layer between the two liners at 175 ° C. for 30 seconds in the oven starting at Example 1, ie 100% expansion. It was a pressure sensitive adhesive strip. Room temperature (without the PET liners) was cooled in (20 ℃), the adhesive composition layer had a thickness of less than 131 ㎛, density and 10 ㎛ of 572 ㎏ / ㎥ surface roughness (R _a).

By die-cutting, in each case a pressure sensitive adhesive strip of the desired dimensions was obtained.

Examples 4 and 5:

The adhesive solution 1 (from Example 1) was mixed with 1% by weight of unexpanded Expancel 920 DU20 microballoons using microballoons in the form of a slurry in benzene. The resulting mixture is subsequently evaporated at 100 ° C. for 15 minutes, followed by drying the composition layer and then on a PET liner provided with a silicone release layer with a layer thickness such that the coat weight is 38 g / m ² . Coating immediately coated.

Thereafter, after laminating the second PET liner on the free surface of the resulting dried adhesive composition layer, the adhesive composition layer was applied at 140 ° C. for 30 seconds (Example 4) or at 175 ° C. for 10 seconds (Example 5). Some foaming was carried out between the two liners in the oven. After cooling at room temperature (20 ° C.), the adhesive composition layer (without PET liner) from Example 4 had a foaming degree of 44%, a thickness of 42 μm, a density of 906 kg / m 3 and a roughness of less than 10 μm (R _a ); Embodiment the adhesive composition layer (without the PET liners) from 5 it had a roughness (R _a) of less than 49% degree of foaming, 42 ㎛ thickness, density, and 10 ㎛ of 895 ㎏ / ㎥.

By die-cutting, in each case a pressure sensitive adhesive strip of the desired dimensions was obtained.

Comparative Examples 6 to 8:

Comparative Example 6 was a pressure sensitive adhesive strip from Examples 4 or 5 but before foaming. The adhesive composition layer (without the PET liners) had a roughness (R _a) of less than 38 ㎛ thickness, density, and 10 ㎛ of 1000 ㎏ / ㎥.

Comparative Example 7 is that Example 4, except that the preparation comprises a full expansion of the adhesive composition layer between two liners at 175 ° C. for 15 seconds starting from Example 4 or 5, i. Or a pressure sensitive adhesive strip from 5. After cooling at room temperature (20 ℃), had the adhesive composition layer (without the PET liners) is of 48 ㎛ thickness, 786 ㎏ / ㎥ density and less than 10 ㎛ surface roughness (R _a) of the.

Comparative Example 8 is obtained from Examples 4 or 5 except that preparation comprises overexpansion to -88% of the adhesive composition layer between two liners at 175 ° C. for 120 seconds in an oven starting from Example 4 or 5 Pressure sensitive adhesive strip. The value of "-88%" here means that the increase in thickness of the unexpanded pressure-sensitive adhesive strip for the fully expanded pressure-sensitive adhesive strip as a result of overexpansion was lost again by 88%. Room temperature (without the PET liners) was cooled in (20 ℃), the adhesive composition layer had a thickness of less than 39 ㎛, density and 10 ㎛ of 975 ㎏ / ㎥ surface roughness (R _a).

By die-cutting, in each case a pressure sensitive adhesive strip of the desired dimensions was obtained.

Examples 9 and 10:

Adhesive solution 1 (from Example 1) was mixed with 1.5% by weight of unexpanded Expancel 920 DU40 microballoons using microballoons in the form of a slurry in benzene. The resulting mixture is subsequently evaporated at 100 ° C. for 15 minutes, thus drying the composition layer and then on a PET liner provided with a silicone release layer with a layer thickness such that the coat weight is 60 g / m ² . Coating immediately coated.

Thereafter, after laminating the second PET liner on the free surface of the resulting dried adhesive composition layer, the adhesive composition layer was applied at 140 ° C. for 30 seconds (Example 9) or at 175 ° C. for 10 seconds (Example 10). Some foaming was carried out between the two liners in the oven. After cooling at room temperature (20 ° C.), the adhesive composition layer (without PET liner) from Example 9 had a foaming degree of 29%, a thickness of 71 μm, a density of 885 kg / m 3 and a roughness of less than 10 μm (R _a ); Embodiment the adhesive composition layer (without the PET liners) from 10 it had a 69% foaming degree, (R _a) of less than the thickness of 89 ㎛, density and 10 ㎛ of 722 ㎏ / ㎥ roughness.

By die-cutting, the pressure-sensitive adhesive strips of the invention in each case of the desired dimensions were obtained.

Comparative Examples 11 to 13:

Comparative Example 11 was a pressure sensitive adhesive strip from Examples 9 or 10 but before foaming. The adhesive composition layer (without the PET liners) had a less than 61 ㎛ of thickness, density and 10 ㎛ of 1000 ㎏ / ㎥ roughness (R _a).

Comparative Example 12 is Example 9 except that the preparation comprises a full expansion of the adhesive composition layer between the two liners at 175 ° C. for 15 seconds starting from Example 9 or 10, ie 100% expansion. Or pressure-sensitive adhesive strip from 10. Room temperature (without the PET liners) was cooled in (20 ℃), the adhesive composition layer had a surface roughness (R _a) of less than 103 ㎛ thickness, density, and 10 ㎛ of 595 ㎏ / ㎥.

Comparative Example 13 is from Example 9 or 10 except that the preparation includes overexpansion to -12% of the adhesive composition layer between two liners at 175 ° C. for 60 seconds in an oven starting from Example 9 or 10. Pressure sensitive adhesive strip. A value of “-12%” here means that the thickness increase of the unexpanded pressure-sensitive adhesive strip on the fully expanded pressure-sensitive adhesive strip as a result of overexpansion was lost again by 12%. Room temperature (without the PET liners) was cooled in (20 ℃), the adhesive composition layer had a thickness of less than 95 ㎛, density and 10 ㎛ of 645 ㎏ / ㎥ surface roughness (R _a).

By die-cutting, in each case a pressure sensitive adhesive strip of the desired dimensions was obtained.

Examples 14-18:

The adhesive solution 1 (from Example 1) was mixed with 1.5% by weight of unexpanded Expancel 920 DU20 microballoons using microballoons in the form of a slurry in benzene. The resulting mixture is subsequently evaporated at 100 ° C. for 15 minutes, followed by drying the composition layer and then on a PET liner provided with a silicone release layer with a layer thickness such that the coat weight is 10 g / m ² . Coating immediately coated.

Thereafter, after laminating the second PET liner on the free surface of the resulting dried adhesive composition layer, the adhesive composition layer was allowed to proceed at 130 ° C. for 10 seconds (Example 14) and at 130 ° C. for 20 seconds (Example 15). And some foaming between the two liners in an oven for 60 seconds at 130 ° C. (Example 16), 20 seconds at 140 ° C. (Example 17) or 60 seconds at 150 ° C. (Example 18). After cooling at room temperature (20 ° C.), the adhesive composition layer (without PET liner) from Example 14 had a foaming degree of 27%, a thickness of 11 μm, a density of 913 kg / m 3 and a roughness of less than 10 μm (R _a ); Embodiment the adhesive composition layer (without the PET liners) from 15 had a roughness (R _a) of less than 38% degree of foaming, and a density of 11.5 ㎛ 10 ㎛ of thickness, 878 ㎏ / ㎥; Had performed an adhesive composition layer (PET liner is not) it is also less than 59% of the foam, of 12.5 ㎛ thickness, density, and 10 ㎛ of 813 ㎏ / ㎥ roughness (R _a) from Example 16; Embodiment had an adhesive layer composed of the roughness degree of the foam is 73% (without the PET liners), and a density less than 10 ㎛ a thickness of 13 ㎛, 768 ㎏ / ㎥ ( R a) from Example 17; Embodiment the adhesive composition layer (without the PET liners) from 18 had a 86% foaming degree, the roughness (R _a) of less than 13.5 ㎛ of thickness, density and 10 ㎛ of 725 ㎏ / ㎥ of.

By die-cutting, the pressure-sensitive adhesive strips of the invention in each case of the desired dimensions were obtained.

Comparative Examples 19 to 21:

Comparative Example 19 was a pressure sensitive adhesive strip from Examples 14-18 but before foaming. The adhesive composition layer (without the PET liners) had a thickness of less than 10 ㎛, density and 10 ㎛ of 1000 ㎏ / ㎥ roughness (R _a).

Example 14 compares Example 14 except that the manufacture includes a full expansion of the adhesive composition layer between two liners at 170 ° C. for 20 seconds in an oven starting from Examples 14-18, that is, a degree of expansion of 100%. Pressure sensitive adhesive strips from to 18. After cooling at room temperature (20 ° C.), the adhesive composition layer (without PET liner) had a thickness of 14 μm and a density of 680 kg / m 3.

Comparative Example 21 is from Examples 14-18 except that the preparation includes overexpansion to -62% of the adhesive composition layer between two liners at 170 ° C. for 60 seconds in an oven starting from Examples 14-18. Pressure sensitive adhesive strip. The value of "-62%" here means that the thickness increase of the unexpanded pressure-sensitive adhesive strip on the fully expanded pressure-sensitive adhesive strip as a result of overexpansion was lost again by 62%. After cooling at room temperature (20 ° C.), the adhesive composition layer (without PET liner) had a thickness of 11.5 μm and a density of 880 kg / m 3.

By die-cutting, in each case a pressure sensitive adhesive strip of the desired dimensions was obtained.

Example 22:

Pressure sensitive adhesive strips of the present invention based on acrylate compositions were prepared.

For this purpose, the base polymer P1, ie polyacrylate, was prepared in solution via free-radical polymerization. Here a conventional reactor for free-radical polymerization was charged with 47.5 kg 2-ethylhexyl acrylate, 47.5 kg n-butyl acrylate, 5 kg acrylic acid and 66 kg benzine / acetone (70/30). After passing nitrogen gas for 45 minutes with stirring, the reactor was heated to 58 ° C. and 50 g of AIBN was added. The external heating bath was then heated to 75 ° C. and the reaction was continued at this external temperature. After 1 hour, another 50 g of AIBN was added and after 4 hours the mixture was diluted with 20 kg of benzine / acetone mixture. After 5.5 and 7 hours, 150 g of additional bis (4-tert-butylcyclohexyl) peroxydicarbonate initiator was added at each time. After 22 hours of reaction time, the polymerization was stopped and the mixture was cooled to room temperature (20 ° C.). The average molecular weight M _w of the polyacrylate was 386,000 g / mol and the polydispersity PD (M _w / M _n ) was 7.6.

Thereafter, 100% by weight of base polymer P1 was adjusted to 38% by weight of solids content by the addition of benzine and acetone. Then, based on the weight of the base polymer used, 0.075% by weight of the covalent crosslinker Erysis GA 240 (N, N, N ', N'-tetrakis (2,3-epoxypropyl) -m from Emerald Performance Materials) Xylene-α, α'-diamine) was added. The mixture was stirred while adding 2% by weight of unexpanded Expancel 920 DU20 microballoons in benzine / acetone at room temperature (20 ° C.) for 15 minutes. The resulting mixture is subsequently evaporated at 100 ° C. for 15 minutes, followed by drying the composition layer and then on a PET liner provided with a silicone release layer with a layer thickness such that the coat weight is 85 g / m ² . Coating immediately coated.

Thereafter, after laminating the second PET liner on the free surface of the resulting dried adhesive composition layer, the adhesive composition layer was partially foamed between two liners in an oven at 160 ° C. for 20 seconds. After cooling at room temperature (20 ℃), had an adhesive layer composed of the roughness of the road firing of 78% (without the PET liners), less than the density and 10 ㎛ of 105 ㎛ _{thickness, 805 ㎏ / ㎥ (R a} ). By die-cutting, pressure-sensitive adhesive strips of the desired dimensions were obtained.

Comparative Examples 23 and 24:

Comparative Example 23 was a pressure sensitive adhesive strip from Example 22 but before foaming. The adhesive composition layer (without the PET liners) had a roughness (R _a) of less than the thickness of 80 ㎛, density and 10 ㎛ of 1056 ㎏ / ㎥.

Comparative Example 24 was prepared from Example 22 except that the preparation started from Example 21 and included in the oven a full expansion of the adhesive composition layer between the two liners at 160 ° C. for 30 seconds, ie 100% expansion. It was a pressure sensitive adhesive strip. (Without the PET liners), the adhesive composition layer was cooled at room temperature (20 ℃) had a roughness (R _a) of less than 10 and a density of 115 ㎛ ㎛ thickness, 735 ㎏ / ㎥.

By die-cutting, in each case a pressure sensitive adhesive strip of the desired dimensions was obtained.

Example 25:

Pressure sensitive adhesive strips of the invention were prepared based on polyacrylate-styrene block copolymer (SBC) blends.

To this end, a mixture was prepared under Example 21 comprising 42.425 wt% base polymer P1, 37.5 wt% Dertophene T resin and 20 wt% Kraton D 1118 as described above. Dertophene T is a terpene-phenolic resin (softening point 110 ° C .; M _w = 500 to 800 g / mol; PD = 1.50) from DRT resin. Kraton 1118 is a styrene from Kraton Polymers with 78 weight percent 3-block, 22 weight percent 2-block, 33 weight percent block polystyrene content and 150,000 g / mol 3-block component molecular weight (M _w ). Butadiene-styrene block copolymer. The addition of benzine resulted in a solids content of 38% by weight. The mixture of polymer and resin was stirred until the resin was clearly completely dissolved. Thereafter, 0.075% by weight of the covalent crosslinker Erysis GA 240 (N, N, N ', N'-tetrakis (2,3-epoxypropyl) -m-xylene-α, α'-diamine) from Emerald Performance Materials Was added. The weight ratios of the dissolved components are based on the dry weight of the solutions respectively formed. The mixture was stirred for 15 minutes at room temperature (20 ° C.) with the addition of 0.8% by weight of unexpanded Expancel 920 DU20 microballoons. The resulting mixture is subsequently evaporated at 100 ° C. for 15 minutes, followed by drying the composition layer and then on a PET liner provided with a silicone release layer with a layer thickness such that the coat weight is 130 g / m ² . Coating immediately coated.

Thereafter, after laminating the second PET liner on the free surface of the resulting dried adhesive composition layer, the adhesive composition layer was partially foamed between two liners in an oven at 160 ° C. for 20 seconds. After cooling at room temperature (20 ℃), it had an adhesive layer composed of the roughness (R _a) of (without the PET liners) is less than even 40% of the foam, density and 10 ㎛ of 105 ㎛ thickness, 963 ㎏ / ㎥. By die-cutting, pressure-sensitive adhesive strips according to the invention of the desired dimensions were obtained.

Comparative Examples 26 and 27:

Comparative Example 26 was a pressure sensitive adhesive strip from Example 25 but before foaming. The adhesive composition layer (without the PET liners) had a roughness (R _a) of less than 127 ㎛ thickness, density, and 10 ㎛ of 1024 ㎏ / ㎥.

Comparative Example 27 was obtained from Example 25 except that the preparation started from Example 24 and included in the oven a full expansion of the adhesive composition layer between the two liners at 160 ° C. for 30 seconds, ie 100% expansion. It was a pressure sensitive adhesive strip. After cooling at room temperature (20 ℃), it had an adhesive layer composed of the roughness (R _a) of (without the PET liners) is less than 149 ㎛ thickness, density, and 10 ㎛ of 872 ㎏ / ㎥.

By die-cutting, in each case a pressure sensitive adhesive strip of the desired dimensions was obtained.

Table 1 below shows the impact resistance (penetration resistance) and bonding strength to steel for the single layer pressure sensitive adhesive strips of the present invention (examples) and as a comparative example for the single layer pressure sensitive adhesive strips.

Table 1: Impact and Bond Strength of Single Layer Pressure Sensitive Adhesive Strips of the Invention and Comparative Example

Exemplary pressure sensitive adhesive strips show that some foamed self-adhesive compositions are surprisingly similar and even actually have improved impact resistance compared to corresponding pressure sensitive adhesive strips having fully foamed self-adhesive compositions. For example, impact resistance (penetration resistance) in the z direction is similar or often even improved. Especially for foaming degrees of from about 65% to about 90%, for example from about 70% to about 80%, in permeability with respect to full foaming regardless of the base polymer, microballoon type and the content used and coat weight. A marked improvement is usually found once again.

When using blends consisting of polyacrylate and styrene block copolymers in pressure sensitive adhesive strips, a marked improvement in penetration resistance was also found at foaming levels of only about 40% compared to the corresponding pressure sensitive adhesive strips with full foaming. ; Example 25 and Comparative Example 27 Comparison.

In particular, pressure sensitive adhesive strips having a very low coat weight of 10 g / m 2 with some suitable degrees of foaming have been found to be advantageous in terms of impact resistance over corresponding fully foamed pressure sensitive adhesive strips; Comparison of Examples 17 and 18 with Comparative Example 20. Without being bound by this theory, this is due in particular to the formation of a clear monolayer by microballoons in some foamed self-adhesive composition layers (see FIGS. 5A and 6A). In contrast, for such low coat weights, even the relatively small unexpanded Expancel 920DU20 microballoons used frequently protrude from the adhesive composition after full foaming, which is undesirable according to the present invention. In addition, exemplary pressure sensitive adhesive strips with some foamed self-adhesive compositions typically have improved bond strengths, ie binding strength, as compared to corresponding pressure sensitive adhesive strips with fully foamed self-adhesive compositions from Comparative Examples. .

The unfoamed and overexpanded pressure sensitive adhesive strips from the comparative examples, in contrast, decrease with respect to impact resistance compared to the corresponding fully foamed pressure sensitive adhesive strips.

Further, the preparation of the pressure-sensitive adhesive strip of the present invention, which is then constructed from permanent carriers coated on both sides with a self-adhesive composition layer SK1 based on a partially foamed vinylaromatic block copolymer adhesive composition each with a microballoon (MB) Is described.

The adhesive solution, microballoon type (Expancel 920DU20) and content (1.5 wt.%) And coat weight (10 g / m 2), used in the preparation of the self-adhesive composition layer, are each specified in Examples 14 to 18, unless otherwise specified. Corresponds. The type and thickness of the carriers varied.

Examples 28-30:

After coating the mixture comprising the unexpanded microballoons in each case with a coat weight of 10 g / m 2 on a PET liner equipped with a silicone release agent, the solvent is evaporated at 100 ° C. for 15 minutes and thus The composition layer was dried.

Thus on the clean surface of the resulting adhesive composition dried 36 um thick transparent etched PET film (Example 28), 23 um thick transparent etched PET film (Example 29) or 12 um thick black PET film (Example 30) was laminated.

A second similarly dried adhesive composition layer (similarly 10 g) produced in the same manner to form a symmetrical three-layer composite composed of two adhesive composition layers provided with an inner film layer and a liner on its second surface. Clean surface) (with a coat weight of / m < 2 >).

After drying, the adhesive layer was partially foamed between two liners in an oven at 138 ° C. for 15 seconds. After cooling to room temperature (20 ° C.), the adhesive composition layer was obtained with a foaming degree of 88% and a density of 720 kg / m 3 (Example 28), a foaming degree of 78% and a density of 750 kg / m 3 (Example 29) or It had a degree of foaming of 94% and a density of 700 kg / m 3 (Example 30). The thickness of the three layer system (without PET liner) was 70 μm (Example 28), 54 μm (Example 29) or 44 μm (Example 30). By die-cutting, the pressure-sensitive adhesive strips of the invention in each case of the desired dimensions were obtained.

Comparative Examples 31 to 33:

Comparative Examples 31-33 were pressure sensitive adhesive strips from Examples 28-30, but before foaming. In each case the density of the adhesive composition layer was 1000 kW kg / m 3. The thickness of the pressure-sensitive adhesive strip (without PET liner) was 62 μm (Comparative Example 31), 52 μm (Comparative Example 32) or 36 μm (Comparative Example 33). By die-cutting, in each case a pressure sensitive adhesive strip of the desired dimensions was obtained.

Example 34:

Example 34 was a pressure sensitive adhesive strip from Example 28, except that a colorless polyurethane film (PEP film) having a thickness of 30 μm was used in place of the transparent etched PET film. After cooling to room temperature (20 ° C.), the adhesive composition layer had a foaming degree of 69% and a density of 780 kg / m 3. The thickness of the three layer system (without PET liner) was 57 μm. By die-cutting, pressure-sensitive adhesive strips of the desired dimensions were obtained.

Comparative Example 35:

Comparative Example 35 was a pressure sensitive adhesive strip from Example 34 but before foaming. The density of the adhesive composition layer was 1000 kg / m 3. The thickness of the pressure sensitive adhesive strip (without PET liner) was 54 μm. By die-cutting, pressure-sensitive adhesive strips of the desired dimensions were obtained.

Example 36:

Example 36 was a pressure sensitive adhesive strip from Example 28 except that a polyethylene foam core (PE foam core) having a thickness of 70 μm was used in place of the transparent etched PET film. After cooling to room temperature (20 ° C.), the adhesive composition layer had a foaming degree of 78% and a density of 750 kg / m 3. The thickness of the three layer system (without PET liner) was 107 μm. By die-cutting, pressure-sensitive adhesive strips of the desired dimensions were obtained.

Example 37:

Example 37 was a pressure sensitive adhesive strip from Example 36 except that the two adhesive composition layers were in each case characterized by a coat weight of 35 g / m 2. After cooling to room temperature (20 ° C.), the adhesive composition layer had a foaming degree of 81% and a density of 740 kg / m 3. The thickness of the three layer system (without PET liner) was 165 μm. By die-cutting, pressure-sensitive adhesive strips of the desired dimensions were obtained.

Comparative Example 38:

Comparative Example 38 was a pressure sensitive adhesive strip from Example 36 but before foaming. The density of the adhesive composition layer was 1000 kg / m 3. The thickness of the pressure sensitive adhesive strip (without PET liner) was 97 μm. By die-cutting, pressure-sensitive adhesive strips of the desired dimensions were obtained.

Example 39:

Example 39 was a pressure sensitive adhesive strip from Example 28 except that a film based on styrene block copolymer (SBC) having a thickness of 70 μm was used in place of the transparent etched PET film. In addition, some foaming was performed at 150 ° C. for 20 seconds rather than at 138 ° C. for 15 seconds. After cooling to room temperature (20 ° C.), the adhesive composition layer had a foaming degree of 78% and a density of 750 kg / m 3. The thickness of the three layer system (without PET liner) was 100 μm. By die-cutting, pressure-sensitive adhesive strips of the desired dimensions were obtained.

Comparative Examples 40-42:

Comparative Example 40 was a pressure sensitive adhesive strip from Example 39 but before foaming. The density of the adhesive composition layer was 1000 kg / m 3. The thickness of the pressure sensitive adhesive strip (without PET liner) was 92 μm. By die-cutting, pressure-sensitive adhesive strips of the desired dimensions were obtained.

Comparative Examples 41 and 42 were pressure sensitive adhesive strips from Example 39 except that they each fully foamed at 170 ° C. for 20 seconds. In Comparative Example 42, a film based on styrene block copolymers and with a lower thickness of 50 μm was also used. The adhesive composition layer in each case had a density of 680 kg / m 3. The thickness of the pressure-sensitive adhesive strip was 111 μm (Comparative Example 41) or 100 μm (Comparative Example 42). By die-cutting, in each case a pressure sensitive adhesive strip of the desired dimensions was obtained.

Table 2 below shows the performance of the drop-top test (as described in the Test Methods section) for a three layer pressure sensitive adhesive strip of the present invention (example) and as a comparative example for a three layer pressure sensitive adhesive strip which is not the invention. It indicates the impact resistance (penetration resistance) and destruction type registered in.

The properties of the three layer pressure sensitive adhesive strips from the examples or comparative examples of Table 2 enable the same conclusion as the single layer pressure sensitive adhesive strips of Table 1. For example, what is more specifically found is that the three layer pressure sensitive adhesive strip with some foamed self-adhesive composition is surprisingly comparable to the impact resistance (penetration resistance) against the corresponding pressure sensitive adhesive strip with fully foamed self-adhesive composition. Has In addition, there is a marked decrease in the penetration resistance of pressure-sensitive adhesive strips with unfoamed self-adhesive compositions compared to corresponding pressure-sensitive adhesive strips with some foamed self-adhesive compositions.

Table 2: Impact Resistance and Fracture Types of Three Layer Pressure Sensitive Adhesive Strips of the Invention and Comparative Example

In addition, the comparison of Examples 36 and 37 shows that only 35 g / m 2 of partially foamed self-adhesive composition layer (SK1), for the coat weight of some 10 g / m 2 of partially foamed self-adhesive composition layer (SK1) It is shown that it is possible to provide a three-layer pressure sensitive adhesive strip having an impact resistance comparable to that of a corresponding pressure sensitive adhesive strip having a coat weight (see especially values from the drop-top test). Thus, the thinner partially foamed self-adhesive composition layer SK1 surprisingly does not cause a lower impact value here.

In addition, experiments in which the degree of foaming of the self-adhesive composition layer increased in the drop-top test showed a tendency to foam splitting the self-adhesive composition layer rather than breaking the adhesive (see pressure-sensitive adhesive strip comprising PET, PU or SBC carriers). ). When using a carrier made of PE foam, partial expansion of the outer layer (self-adhesive composition layer) results in that the entire structure is from anchoring fracture, that is, PE foam in the breakdown between the self-adhesive composition layer and the PE foam carrier. It is also interesting to have the effect of moving to division of the carrier. It is apparent that some foaming of the self-adhesive composition layer improves its fixation with the PE foam carrier. Example 36 also shows that even with a coat weight of some foamed self-adhesive composition layer (SK1) of only 10 g / m ² , 3 with a polyethylene foam carrier whose destruction type is splitting of polyethylene foam in the drop-top test. To provide a layer pressure sensitive adhesive strip (here also with a coat weight of 35 g / m ² ; see Example 37).

In addition, the experiments by chance show that in the drop-top test, the type of failure depends not only on the degree of foaming of the self-adhesive composition layer but also on the type of carrier used. For example, Examples 29, 36, and 39 may divide or otherwise divide some foamed self-adhesive composition layer or foamed carrier with the same degree of foaming (and the same chemical composition) of the self-adhesive composition layer depending on the carrier used. Indicates that adhesive breakage can be considered. Thus, the desired breaking profile can be adjusted via the degree of foam or through the carrier used.

Test Methods

Unless otherwise stated, all measurements were performed at 23 ° C. and 50% relative air humidity.

Mechanical and adhesion data were confirmed as follows:

Tensile Strength, Breaking Strength (breaking force) and Elongation at Break (Test Method R1)

For example, elongation at break, fracture strength and tensile strength of film carriers were measured using a test strip type 2, a test strip having a width of 20 mm at a separation rate of 100 mm / min according to DIN EN ISO 527-3. The initial distance between the gripping clamps was 100 mm. Test conditions were 23 ° C. and 50% relative air humidity.

Separation

Separation force (striping force or stripping stress) is determined using a pressure sensitive adhesive strip having a length of 50 mm x 20 mm in width with a grip tab area that is non-touch-tacky at the top. It became. The pressure-sensitive adhesive strips were joined in a matching arrangement with each other and between two steel sheets having dimensions of 50 mm x 30 mm in each case at a contact pressure of 50 Newtons. Each of the steel sheets has a hole at the bottom for receiving an S-shaped steel ring. The bottom of the steel hook has an additional steel plate, whereby the test apparatus can be fixed for measurement in the lower clamping jaw of the tensile tester. The binder was stored at + 40 ° C. for 24 hours. After conditioning again at room temperature (20 ° C.), the pressure-sensitive adhesive strip was separated at a strain of 1000 mm / min parallel to the bonding surface and in a non-contact manner with respect to the edge regions of the two steel plates. At the same time, the required separation force in Newtons (N) was measured. What is reported is the average (in N / mm 2) of the stripping stress values measured in the region where the pressure-sensitive adhesive strip is separated from the steel substrate over a bond length of 10 mm to 40 mm.

cohesion

Determination of the binding force (according to AFERA 5001) was performed as follows. The prescribed substrate used was a galvanized steel sheet (supplied from Rocholl GmbH) with a thickness of 2 mm. The pressure-sensitive adhesive strip to be inspected was cut into a width of 20 mm and a length of about 25 cm provided with a handling section and immediately pressed onto the selected bonding substrate five times at a forward speed of 10 m / min with a 4 kg steel roll. Immediately after this, the pressure-sensitive adhesive strip was pulled out of the bonding substrate at a speed of v = 300 mm / min with a tensile tester (from Zwick) at an angle of 180 °, and the required force (20 ° C.) was measured at room temperature. The measured value (N / cm) is obtained as the average value from three individual measurements.

thickness

For example, the thickness of the adhesive composition layer, or of the carrier layer, of the pressure sensitive adhesive strip can be determined by a commercial thickness measurement instrument (caliper test instrument), which typically has an accuracy of less than 1 μm. The thickness of the adhesive composition layer is usually subtracted from the thickness of the section (used or separately measurable) of the used carrier or liner of the same dimensions in the thickness of the section defined in terms of the length and width of that layer applied to the carrier or liner. It confirmed by determining. Once the variation in thickness was confirmed, the average of the measurements at at least three representative positions was reported. That is, more particularly, no measurements were made in creases, folds, spots, and the like. In this application, Mod. A 2000 F precision thickness gauge was used for the measurement of the thickness, which had a circular caliper with a diameter (plane) of 10 mm. The measuring force was 4N. The value was read 1 second after loading.

density

The density of the layer, for example the adhesive composition layer, was confirmed by forming a quote of the thickness and the applied mass of the layer applied to the carrier or liner.

The coat weight of a layer, for example, an adhesive composition layer, may be determined by the mass of the section of the used carrier or liner of the same dimension in the mass of the section of such layer applied to the carrier or liner, defined in terms of its length and width ( This can be confirmed by determining by subtracting the mass (measurable separately).

The thickness of a layer, for example an adhesive composition layer, may be determined by the thickness of the section of the used carrier or liner having the same dimensions (known or separately) in the thickness of the section of such layer applied to the carrier or liner, defined in terms of its length and width. Can be determined by subtracting the measurable thickness). The thickness of the layer can be determined by commercial thickness measuring instruments (caliper test instruments), which typically have an accuracy of less than 1 μm. Once the variation in thickness was confirmed, the average of the measurements at at least three representative positions was reported. That is, more particularly, no measurements were made in creases, folds, spots, and the like. In this application, Mod. A 2000 F precision thickness gauge was used for the measurement of the thickness, which had a circular caliper with a diameter (plane) of 10 mm. The measuring force was 4N. The value was read 1 second after loading.

DuPont test in the z direction (penetration resistant)

The frame-shaped square sample (outer dimension 33 mm x 33 mm; border width 2.0 mm; inner dimension (window cut-out) 29 mm x 29 mm) was cut from the adhesive tape (pressure sensitive adhesive strip) to be inspected. This sample was attached to a PC frame (outer dimension 45 mm x 45 mm; border width 10 mm; inner dimension (window cut-out) 25 mm x 25 mm; thickness 3 mm). A 35 mm by 35 mm PC window was attached to the other side of the adhesive tape. The combination of the PC frame, the adhesive tape frame and the PC window was performed in such a way that the geometric center and the diagonals were on top of each other (corner-to-corner). The bonding area was 248 mm 2. The bond was pressurized at 248 N for 5 seconds and stored for 24 hours under conditions of 23 ° C./50% relative humidity.

Immediately after storage, the adhesive composite consisting of the PC frame, adhesive tape and PC window was reinforced by the protruding edges of the PC frame in the sample holder with the composites arranged horizontally and the PC window beneath the frame. The sample holder was then inserted centrally into the intended receptacle of the DuPont Impact Tester. A weight of 190 g impact head was used in such a way that a circular impact geometry with a 20 mm diameter would impact in the center and be flush with the window side of the PC window.

A weight with a mass of 150 g guided by two guide rods was allowed to fall vertically from a height of 5 cm onto a composite consisting of a sample holder, a sample and an impact head, thus arranged (test conditions: 23 ° C., relative humidity). 50%). The additional falling height was increased at 5 cm intervals until the introduced impact energy destroyed the sample as a result of the impact stress and the PC window separating from the PC frame.

In order to be able to compare the experiments with different samples, the energy was calculated as follows:

E [J] = height [m] ^* weight [kg] ^* 9.81 m / s ²

Five samples per product were tested and the average energy was reported as an index for penetration resistance.

Drop Tower Test Method (Permeability)

Drop tower test methods, such as the instrument drop device test, serve to measure penetration resistance.

Square samples in the form of frames were cut out from the adhesive tape to be inspected (outer dimensions 33 mm × 33 mm; border width 2 mm; inner dimensions (window cut-out) 29 mm × 29 mm). This sample was fixed to an acetone cleaned steel frame (outer dimensions 45 mm × 45 mm; border width 10 mm; inner dimensions (window cutout) 25 mm × 25 mm). The acetone cleaned steel window (outer dimension 35 mm × 35 mm) was bonded to the other side of the adhesive tape. The combination of the steel frame, the adhesive tape frame and the steel window was performed so that the geometric center and the diagonal overlap each other (corner-to-corner). The bonding area was 248 mm 2. The binder was pressurized at 248 N for 5 seconds and stored for 24 hours under conditions of 23 ° C./50% relative humidity.

Immediately after storage, the test specimens were placed in the sample holder of the instrument dropping device so that the composite was horizontal with the steel window facing down. Measurements were performed with instrument monitoring and automatically using a load weight of 5 kg and a drop height of 10 cm. The kinetic energy introduced by the load weight broke the bond by breaking the adhesive tape between the window and the frame, and the force was recorded by the piezoelectric sensor every second. The accompanying software thus provided a graph of the force / time progression after measurement, from which the maximum force (F _max ) could be determined. The speed of the falling weight was determined by two beams just before the rectangular impact structure affected the window. Assuming that the energy introduced is large relative to the impact resistance of the binder, the progress of the force, the time taken for separation and the speed of the drop weight were used to identify the work performed by the binder, ie separation, before complete separation. Five test specimens of each sample were examined; The final impact resistance result consists of the average of the separation operations or the maximum force on these five samples.

Shock resistance (x, y side)

Square samples in the form of frames were cut out from the adhesive tape to be inspected (outer dimensions 33 mm × 33 mm; border width 2.0 mm; inner dimensions (window cut-out) 29 mm × 29 mm). This sample was attached to a PC frame (outer dimension 45 mm x 45 mm; border width 10 mm; inner dimension (window cutout) 25 mm x 25 mm; thickness 3 mm). A 35 mm by 35 mm PC window was fixed to the other side of the double sided adhesive tape. The combination of the PC frame, the adhesive tape frame and the PC window was performed so that the geometric center and the diagonal overlap each other (corner-to-corner). The bonding area was 48 mm 2. The binder was pressurized at 248 N for 5 seconds and stored for 24 hours under conditions of 23 ° C./50% relative humidity.

Immediately after storage, the adhesive composite consisting of PC frame, adhesive tape and PC sheet was fixed by the protruding edge of the PC frame in the sample holder such that the composite was aligned vertically. The sample holder was then inserted centrally into the intended receptacle of the "DuPont Impact Tester". A weight of 300 grams of impact head was used in such a way that a rectangular impact structure with dimensions 20 mm x 3 mm influenced the center and the end face of the PC window was flushed up.

A weight with a mass of 150 g guided by two guide rods was allowed to fall perpendicularly to the composite consisting of the sample holder, sample and impact head at a height of 5 cm (test conditions: 23 ° C., 50% relative humidity). The additional falling height was increased in 5 cm steps until the impact energy introduced destroyed the sample as a result of the transverse impact stress and the PC window separated from the PC frame.

In order to be able to compare the experiments with different samples, the energy was calculated as follows:

E [J] = height [m] ^* weight [kg] ^* 9.81 m / s ²

Five samples per product were tested and the average energy reported as an index for lab impact.

diameter

The average diameter of the voids formed by the microballoons in the self-adhesive composition layer was determined using the cold cut edge of the pressure sensitive adhesive strip in a scanning electron microscope (SEM) with a 500x magnification. The diameter of the microballoons in the layer of self-adhesive composition to be examined, as seen in the scanning electron micrographs of the five different cold cut edges of the pressure sensitive adhesive strip, was determined in each case graphically and confirmed in the five scanning electron micrographs. The arithmetic mean of all diameters made up constituted the average diameter of the voids formed by the microballoons in the self-adhesive composition layer in the context of the present application. The diameter of the microballoons seen in the micrographs is deduced from the scanning electron micrographs for each individual microballoon in the layer of self-adhesive composition to be examined and considered as its diameter As determined by the graphic means.

Static glass transition temperature (T _g )

The glass transition point (synonymously referred to as the glass transition temperature) is determined at DIN 53 765, with a uniform heating and cooling rate of 10 K / min in all heating and cooling steps (compare DIN 53 765; Section 7.1; Note 1). In particular, it is reported as a measurement result by differential scanning calorimetry (DSC) according to sections 7.1 and 8.1. Sample weight was 20 mg.

DACP

5.0 g of test substance (the tackifying resin sample to be tested) are weighed into a dry test tube and 5.0 g of xylene (isomer mixture, CAS [1330-20-7], ≥ 98.5%, Sigma-Aldrich # 320579 or similar) Is added). The test material was dissolved at 130 ° C. and then cooled to 80 ° C. Any exiting xylene was supplemented with fresh xylene, thus again 5.0 g of xylene was present. Subsequently, 5.0 g of diacetone alcohol (4-hydroxy-4-methyl-2-pentanone, CAS [123-42-2], 99%, Aldrich # H41544 or similar) was added. The test tube was shaken until the test substance completely dissolved. For this purpose, the solution was heated to 100 ° C. Test tubes containing the resin solution were then introduced into a Novomatics Chemotronic Cool cloud point measuring instrument and heated therein to 110 ° C. It was cooled at a cooling rate of 1.0 K / min. The cloud point was optically detected. For this purpose, a temperature of 70% turbidity of the solution was registered. The results were reported in ° C. The lower the DACP value, the higher the polarity of the test substance.

MMAP

5.0 g of test substance (tacked resin specimen under irradiation) were weighed into the dried sample glass and 10 ml of dry aniline (CAS [62-53-3], ≥ 99.5%, Sigma-Aldrich # 51788 or similar). And 5 ml of dry methylcyclohexane (CAS [108-87-2], ≥ 99%, Sigma-Aldrich # 300306 or similar). The test tube was shaken until the test substance completely dissolved. For this purpose, the solution was heated to 100 ° C. Test tubes containing the resin solution were then introduced into a Novomatics Chemotronic Cool cloud point measuring instrument and heated therein to 110 ° C. It was cooled at a cooling rate of 1.0 K / min. The cloud point was visually detected. For this purpose, a temperature of 70% turbidity of the solution was registered. The results were reported in ° C. The lower the MMAP, the higher the directionality of the test material.

Softening temperature

For example, the softening temperature of tackifying resins, polymers or polymer blocks is known as rings & balls and is determined according to the relevant methodology standardized according to ASTM E28.

Gel Permeation Chromatography (GPC)

(i) M _P : GPC An analytical method suitable for determining the molar mass of individual polymer modes in a mixture of different polymers. The molar mass distribution of the block copolymers that can be used for the purposes of the present invention and prepared by living anionic polymerization, is typically a polymer mode that can be assigned to triblock copolymers, diblock copolymers or multiblock copolymers. It is narrow enough so that it can appear in sufficient resolution with each other in grams. The peak molar mass for the individual polymer mode can then be read from the elgram. Peak molar mass (M _P ) is determined by gel permeation chromatography (GPC). The eluent used was THF. The measurement was performed at 23 ° C. The precolumns used were PSS-SDV, 5μ, 10 ³ mm ³ , ID 8.0 mm x 50 mm. For separation, the columns used were PSS-SDV, 5 μ, 10 ³ mm ³ and 10 ⁴ mm ³ and 10 ⁶ mm 3, ID 8.0 mm × 300 mm, respectively. Sample concentration was 4 g / l and flow rate was 1.0 mL per minute. Measurements were performed on the PS standard (μ = μm; 1 A = 10 ^-10 m).

(ii) M _n , M _w , PD: number-average molar mass (M _n ), weight-average molecular weight (M _W ) And values for polydispersity (PD) were based on measurements by gel permeation chromatography. The measurement was performed using a clearly filtered 100 μl sample (sample concentration 1 g / L). The eluent used was tetrahydrofuran with 0.1% by volume trifluoroacetic acid. The measurement was performed at 25 ° C. The precolumns used were columns of PSS-SDV type, 5 μ, 10 ³ mm ³ , ID 8.0 mm × 50 mm. For separation, PSS-SDV type, 5 μ, 10 ³ μs and 10 ⁵ μs and 10 ⁶ μs, ID 8.0 mm × 300 mm columns (column from Polymer Standards Service; detected by Shodex RI71 Differential Refractometer) Used. The flow rate was 1.0 mL per minute. Calibration was performed on PMMA standards (polymethylmethacrylate calibration) or polystyrene in case of (synthetic) rubber.

Elasticity / elasticity

To measure the elasticity, the film carrier was stretched to 100% and this stretch was held for 30 seconds before stopping. After the waiting time of 1 minute, the length was measured again.

Elasticity was then calculated as follows:

R = ((L ₁₀₀ -L _end ) / L ₀ ) * 100

R = elasticity (%)

L ₁₀₀ : Length of film carrier after 100% elongation

L ₀ : Length of film carrier before stretching

L _end : Length of film carrier after 1 minute stop

Elasticity here corresponds to elasticity.

Modulus

Modulus of elasticity refers to the mechanical resistance that a material provides against elastic deformation. This is determined as the ratio of strain (σ) required for the achieved elongation (ε), where ε is the index of the length change ΔL and the length L _{0 in} the Hook's deformation regime of the specimen. Definition of elastic modulus is described, for example, in Taschenbuch der Physik [Physics Handbook] (H. Stoecker (ed.), Taschenbuch der Physik, 2nd ed., 1994, Verlag Harri Deutsch, Frankfurt, p. 102-110). It is explained.

In order to determine the elastic modulus of the film, tensile strain characteristics were applied according to DIN EN ISO 527-3 / 2/300, according to DIN EN ISO 527-3 / 2/300, using Type 2 specimens (150 mm long and 15 mm wide rectangular test film strips). Test speeds of mm / min, clamping length of 100 mm, and initial forces of 0.3 N / cm were confirmed, where the test strips were sized with sharp blades for verification of data. Zwick tensile tester (model Z010) was used. Tensile strain characteristics were measured in the machine direction (MD). A 1000 N (Zwick Roell Kap-Z 066080.03.00) or 100 N (Zwick Roell Kap-Z 066110.03.00) load cell was used. The modulus of elasticity was confirmed by graphical means from the measurement curve and reported in GPa by determining the slope of the starting region of the curve, which is characteristic of the behavior associated with Hook's law.

Surface Roughness (R _a )

The surface roughness (R _a) were determined by laser triangulation.

The PRIMOS system used consisted of a lighting unit and a recording unit. With the aid of a digital micro-mirror projector, the lighting unit projected a line onto the surface. These projected parallel lines were deflected or modulated by the surface structure. To register the modulated lines, a CCD camera was used that was arranged at a particular angle called a triangulation angle.

Size of the measuring field: 14.5 × 23.4 ㎡

Profile length: 20.0 mm

Area roughness: 1.0 mm from the edge (Xm = 21.4 mm; Ym = 12.5 mm)

Filtering: 3rd-order polynomial filter

The surface roughness (R _a) represents the average absolute distance from the center line (regression line) of the roughness profile within the average height of roughness, in particular, evaluation range. In other words, R _a is the arithmetic mean roughness, that is, the arithmetic mean of all profile values in the roughness profile.

 Corresponding measuring equipment can be purchased from suppliers including GFMesstechnik GmbH (Teltow, Germany).

Claims (17)

Comprising at least one layer (SK1), preferably exactly one layer (SK1) of the self-adhesive composition partially foamed with microballoons, wherein the degree of foaming of the layer (SK1) is at least 20% to less than 100%, Pressure sensitive adhesive strip. 2. The pressure sensitive adhesive strip according to claim 1, wherein the pressure sensitive adhesive strip can be detached again in an essentially residue-free and non-destructive manner at the bonding surface by stretching. The pressure sensitive adhesive strip according to claim 1 or 2, characterized in that the pressure sensitive adhesive strip consists of a layer (SK1). 3. The pressure-sensitive adhesive strip according to claim 1, wherein the pressure-sensitive adhesive strip comprises a layer SK1 and also a layer T of a carrier, in particular a film carrier, said layer SK1 being the surface of the carrier layer T. Pressure-sensitive adhesive strip, characterized in that arranged on one of them. The pressure sensitive adhesive strip further comprises a layer (SK2) consisting of a self-adhesive composition arranged on an opposing surface of the carrier layer (T) from the layer (SK1), said layer (SK2) Preferably, the pressure sensitive adhesive strip is based on a composition partially foamed with microballoons, wherein the degree of foaming of the layer (SK2) is at least 20% to less than 100%. The self-adhesive composition layer (SK1) and / or self-adhesive composition layer (SK2), preferably the degree of foaming of each layer (SK1) and layer (SK2) according to any one of the preceding claims. Are independently 25% to 98%, more preferably 35% to 95%, even more preferably 50% to 90% and especially 65% to 90%, for example 70% to 80%. Pressure-sensitive adhesive strip. 7. The microballoon according to claim 1, wherein the self-adhesive composition layer (SK1) and / or the self-adhesive composition layer (SK2), preferably in each layer (SK1) and layer (SK2). A pressure-sensitive adhesive strip, characterized in that the average diameter of the voids formed by is independently less than 20 μm, more preferably less than 15 μm. 8. The self-adhesive composition layer (SK1) and / or the self-adhesive composition layer (SK2), preferably each layer (SK1) and layer (SK2) independently of any one of the preceding claims. Pressure-sensitive adhesive strip, characterized in that it has a thickness of less than 20 μm, more preferably 15 μm or less. The self-adhesive composition layer (SK1) and / or the self-adhesive composition layer (SK2), preferably each layer (SK1) and layer (SK2) independently of any one of the preceding claims. A coat weight (g / m 2) less than the average diameter (μm) of the voids formed by the microballoons in the corresponding self-adhesive composition layer, and the average of the voids formed by the microballoons of the self-adhesive composition layer A pressure-sensitive adhesive strip, characterized in that the ratio of coat weight (g / m 2) to diameter (μm) is preferably from 0.6 to 0.9, and in particular from 0.7 to 0.8. The self-adhesive composition layer (SK1) and / or the self-adhesive composition layer (SK2), preferably both layer (SK1) and layer (SK2) are micro A pressure-sensitive adhesive strip, characterized in that it has a single layer of balloons. The self-adhesive composition layer (SK1) and / or the self-adhesive composition layer (SK2), preferably each layer (SK1) and layer (SK2) independently of any one of the preceding claims. , 15 ㎛ less than, the preferably, 10 ㎛ less, more preferably, less than 5 ㎛, even more preferably, less than 3 ㎛, in particular, less than 2 ㎛, for example, surface roughness of less than 1 ㎛ (R _a) Characterized in that it has a pressure-sensitive adhesive strip. The film carrier layer (T) is not stretchable and the film carrier layer (T) is preferably 5 to 125 μm, more preferably 5 to 40 μm. And in particular, having a thickness of less than 5 to 10 μm, for example 6 μm. The film carrier layer (T) is stretchable and the film carrier layer (T) is preferably from 50 to 150 μm, more preferably from 60 to 100 μm and In particular, the pressure-sensitive adhesive strip, characterized in that it has a thickness of 70 to 75 μm, for example 70 μm. The method according to claim 13, wherein the stretchable film carrier layer T is a film based on vinylaromatic block copolymers, preferably styrene block copolymers, wherein the film is preferably not foamed. Adhesive strips. The self-adhesive composition layer (SK1) and / or the self-adhesive composition layer (SK2), preferably both layer (SK1) and layer (SK2) are vinyls. A pressure-sensitive adhesive strip, characterized in that it is based on an aromatic block copolymer composition or an acrylate composition, and in particular on a vinylaromatic block copolymer composition. 16. A method of making a pressure sensitive adhesive strip according to any one of claims 1 to 15, comprising the steps of: applying a corresponding self-adhesive composition layer comprising unexpanded microballoons at a temperature suitable for foaming, During the period in which the desired degree of foaming is achieved after cooling, the heat treatment produces a partially foamed self-adhesive composition layer (SK1) and optionally, a self-adhesive composition layer (SK2) with microballoons. The pressure-sensitive adhesive according to any one of claims 1 to 15 for the coupling of parts, for example accumulators and electronic devices, for example mobile devices, for example mobile phones. Use of the strip.

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