Method for producing a multi-phase polymer system

Abstract

The invention relates to a method for producing polymers on the basis of monomers with functionalised vinyl groups. By virtue of the method, polymers with a controlled architecture can be efficiently produced without the need for a subsequent thermal loading process in that the achieved polymer architecture and the polymer mechanical properties based thereon are maintained during further processing of the polymers. This is achieved by a method for producing a polymer system present in at least two phases, comprising the following steps: a) polymerizing a monomer composition I, comprising in total at least 80 wt.% of one or more monomers selected from the group consisting of methacrylic acid esters, methacrylamides and monomers with at least one polymerisable vinyl group, in order to form a polymerisate A; and b) polymerizing a monomer composition II, comprising in total at least 80 wt.% of one or more monomers selected from the group consisting of methacrylic acid esters, methacrylamides and monomers with at least one polymerisable vinyl group, wherein at least 50 wt.% of the monomers in monomer composition II differ from those in monomer composition I, in the presence of polymerisate A in order to form a polymerisate B, thereby obtaining a polymer system which is present in at least two phases and comprises polymerisates A and B. The method is characterized in that step b) is carried out in a closed casing.

Description

[0001] Process for producing a multiphase polymer system

[0002] The present invention lies in the technical field of polymerization processes, which are used in a wide variety of ways, both with regard to the equipment used and the process conditions, for the targeted production of plastics with specific property profiles. More specifically, the invention proposes a process for producing a multiphase polymer system that comprises two polymerization stages and initially leads to a first polymer, in the presence of which the polymerization is then continued in a closed shell. The most important application background for the multiphase polymer systems produced in this way is pressure-sensitive adhesives for adhesive tapes, which are used to generate both temporary and permanent material bonds in various fields of technology.

[0003] For industrial adhesive tape applications, polymers based on the polymerization of monomers with functionalized vinyl groups are often used. A well-known example of such polymers is poly(meth)acrylate. Poly(meth)acrylates offer several advantages over other plastics used as a basis for adhesive applications. For example, they are highly stable against high-energy radiation and oxidizing substances. In contrast to poly(meth)acrylates, synthetic rubbers and natural rubbers often contain carbon-carbon double bonds, which make these polymers, and thus also adhesive components based on them, vulnerable to UV radiation, oxygen, and ozone, for example. Furthermore, poly(meth)acrylate-based plastic formulations can be transparent and can be used over a wide temperature range.

[0004] In the past, polymers based on monomers with functionalized vinyl groups were regularly produced from solution by free radical polymerization. The polymers are coated from solution onto a support material using a coating bar or similar tool and then dried. To increase cohesion, the polymers are usually crosslinked, which is usually achieved either thermally, by UV radiation, or by electron beam irradiation. The solvent process is economically inefficient overall and environmentally damaging, as the solvents are either not recycled and then pollute the environment, or must be recycled at high energy costs.

[0005] In addition, quality issues also regularly arise. For example, adhesive tapes with higher mass application based on the polymers described are often difficult to produce without bubbles.

[0006] To mitigate these disadvantages, attempts have been made to apply the polymers from the melt to the carrier material using a hot-melt process. However, this technique also has limitations. Since the polymers are still largely produced from solution, the solvent must be removed from the melt before processing. This is done, for example, in a dry extruder. The drying process involves high temperatures and shearing effects on the polymers, so that higher molecular weight polymers in particular experience relatively severe damage during processing. For example, gelling can occur, making the polymers impossible or difficult to coat.Molecular weight reduction can lead to a significant concentration of low-molecular-weight components, which then act as lubricants and cause undesirable properties such as poor shear strength. The prior art describes, in particular, various approaches for processing poly(meth)acrylates into pressure-sensitive adhesives using hot-melt processes.

[0007] Thus, WO 00 / 06637 A1 discloses a process for producing an article, the process comprising: a) melt-mixing a polymer composition and a plurality of microspheres, at least one of which is an expandable polymeric microsphere, under process conditions including temperature and shear rate selected to form an expandable, extrudable composition; b) extruding the expandable, extrudable composition through a die to form a foam having a smooth surface with an Ra value of less than 75 pm; c) at least partially expanding one or more of the expandable polymeric microspheres before the polymer composition leaves the die.WO 2010 / 112346 A1 relates to a process for producing a foamed mass system containing thermally sensitive substances, in which the mass system is foamed in a first step at a first temperature and the thermally sensitive substances, which may be, for example, thermal crosslinkers, are added to the mass system in a subsequent step at a second, lower temperature than the first temperature.

[0008] WO 2008 / 122489 A1 describes a process for the thermal crosslinking of polyacrylates having functional groups which are suitable for entering into linking reactions with epoxy groups, wherein a crosslinker-accelerator system comprising substances containing epoxy groups (crosslinkers) and at least one substance which has an accelerator effect for the linking reaction at a temperature below the melting temperature of the polyacrylate is used.

[0009] Attempts have also been made in the prior art to combine the polymerization and processing of acrylate polymers in a continuous process. WO 2004 / 101627 A1 describes a process for the continuous polymerization of acrylic monomers to polyacrylates in the presence of polymerization-regulating substances, wherein at least one polymerization step is carried out within at least one reaction extruder. Disadvantages of such processes have been identified as including low throughput, high investment costs, and limited flexibility in formula changes.

[0010] Another aspect that influences the properties of polymers based on monomers with functionalized vinyl groups is the polymer architecture. In the distant past, most work was done with statistical copolymers, in which the monomers were randomly distributed throughout the polymer chain. In recent decades, polymers with controlled structures, such as block copolymers or copolymers with a monomer distribution gradient, have come into focus. Attempts are therefore being made to specifically control the property profile of the polymers and the plastic formulations based on them via the distribution or arrangement of the monomers. In this way, it is possible to achieve essentially contradictory properties with one and the same polymer base. In this context, methods of controlled (meth)acrylate polymerization, in particular, have been described in the prior art.WO 2004 / 101627 A1 describes a process for the continuous polymerization of acrylic monomers to polyacrylates in the presence of polymerization-regulating substances, wherein at least one polymerization step is carried out within at least one reaction extruder.

[0011] WO 2013 / 072120 A1 relates to a process for producing acrylate-based polymers, in which a controlled radical polymerization reaction of a reaction mixture comprising at least one acrylate-based monomer is first carried out in the presence of at least one regulator substance having at least one functional group SC=X, where X = S, O or N, wherein the regulator substance is selected from the group comprising dithioesters, dithiocarbonates, dithiocarbamates, trithiocarbonates, imidodithiocarbonates and xanthates (“RAFT regulators”), wherein the majority of the regulator substance molecules are incorporated into the resulting polymer chains, after which the respective polymer chain has the functional group of the incorporated regulator, characterized in that at least one chemical compound having at least two conjugated double bonds (hereinafter referred to as “conjugated diene”) is brought into contact with the polymers thus obtained,so that hetero-Diels-Alder reactions are effected between the double bonds C=X of the functional groups SC=X incorporated into the polymer chains and the conjugated double bonds of the conjugated diene.

[0012] EP 2 607394 A1 discloses a process for producing pressure-sensitive adhesives, in which a controlled radical polymerization reaction of a reaction mixture comprising one or more monomers is carried out in the presence of at least one radical initiator to produce at least one polymer, characterized in that at least one cyclic 1,4-diradical is used as the radical initiator, which is produced by means of a cyclization reaction from a compound having at least two unsaturated CC bonds ("diradical-forming compound"), wherein the polymerization reaction is carried out in the presence of at least one regulator substance ("polymerization regulator").

[0013] WO 2013 / 055978 A1 describes acrylic copolymers that feature a controlled placement of specific functional groups within the polymer structure. The copolymers contain at least two reactive segments and are produced via a controlled radical polymerization process. The copolymers are useful in the production of adhesives and elastomers.

[0014] WO 2018 / 118905 A1 describes a crosslinkable composition comprising a) a polymeric material of the formula wherein

[0015] Ri is hydrogen, alkyl, fluorinated alkyl, aryl, arylky or substituted aralkyl;

[0016] X is oxygen or -NR2, wherein R2 is hydrogen, alkyl, fluorinated alkyl, aryl, aralkyl or substituted aryl; each R3 is alkoxy, fluorinated alkoxy or -N(R4)2, wherein each R4 is alkyl or fluorinated alkyl or together with the nitrogen to which they are both attached form a heterocyclic ring; each P is a polymeric block comprising a polymerized product of a first monomer composition comprising at least one monomer having a single ethylenically unsaturated group; y is an integer from 1 to 5; and b) a second monomer composition miscible with the polymeric material of the formula and comprising a crosslinking monomer having at least two ethylenically unsaturated groups.WO 2018 / 178829 A1 describes controlled radical initiators, reaction mixtures containing them and various ethylenically unsaturated monomers; polymeric materials formed from these reaction mixtures; crosslinkable compositions containing the polymeric materials, and crosslinked compositions formed from them. The controlled radical initiators are bis-dithiocarbamate and bis-dithiocarbonate compounds with a single carbon atom between the two dithiocarbamate or dithiocarbonate groups.

[0017] There is a continuing need for processes for the production of polymers based on monomers with functionalized vinyl groups that can be operated economically and ecologically efficiently and lead to polymers with a controlled architecture that are available for straightforward further processing. The problem remains that polymerization is easiest to handle in solution, but the solvent must be removed for further processing of the polymers. This is often associated with high temperatures, for example, in the feed preheating unit of concentration extruders.These cause a thermal degradation of the regulator substances used, especially in polymers produced by controlled polymerization, which on the one hand often results in a strong odor nuisance and on the other hand, depending on the position of the regulator substances in the polymer, can also lead to polymer degradation and to a change in the mechanical properties of the polymer systems.

[0018] It was an object of the invention to avoid the problems known from the prior art and to provide a process for the production of polymers based on monomers with functionalized vinyl groups, with which polymers with controlled architecture can be produced efficiently and without the need for subsequent thermal stress in such a way that the achieved polymer architecture and the mechanical properties of the polymers based thereon are retained during their further processing.

[0019] It was a further object of the invention to offer such a process that offers high flexibility for changes in the polymer formulation and the desired polymer architecture.

[0020] A supplementary object of the invention was to provide the resulting polymers in an efficient manner so that they can be easily stored and transported and yet are available for efficient further processing both from the melt and from solution.

[0021] A supplementary object of the invention was to provide polymers that can be produced in this way and have good cohesion and good melt processability.

[0022] It was a further additional object of the invention to provide polymers based on monomers with functionalized vinyl groups which are particularly suitable for adhesive tape applications.

[0023] A first and general subject matter of the invention, with which these objects are achieved, is a process for producing a polymer system which is present in at least two phases, comprising the following steps: a) polymerization of a monomer composition I comprising a total of at least 80% by weight of one or more monomers selected from the group consisting of methacrylic acid esters, methacrylamides and monomers having at least one polymerizable vinyl group to form a polymer A; b) polymerization of a monomer composition II comprising a total of at least 80% by weight of one or more monomers selected from the group consisting of methacrylic acid esters, methacrylamides and monomers having at least one polymerizable vinyl group, wherein the monomer composition II consists of at least 50% by weight of-% of its monomers differs from those of the monomer composition I, in the presence of the polymer A to form a polymer B to obtain a polymer system present in at least two phases comprising the polymers A and B; characterized in that step b) takes place in a closed shell.

[0024] Details and embodiments of the invention are described below. Those embodiments that are designated as preferred in any form below are combined in particularly preferred embodiments with features of other embodiments that are designated as preferred in any form below. Combinations of two or more of the embodiments that are designated as particularly preferred in any form below are thus very particularly preferred. Likewise preferred are embodiments in which a feature of one embodiment that is designated as preferred to any extent is combined with one or more further features of other embodiments that are designated as preferred to any extent.

[0025] To the extent that both specific amounts or proportions of an element and preferred embodiments of the element are disclosed below, the specific amounts or proportions of the preferably configured elements are also disclosed. Furthermore, it is disclosed that, with the corresponding specific total amounts or total proportions of the elements, at least some of the elements can be preferably configured, and in particular, that preferably configured elements can in turn be present in the specific amounts or proportions within the specific total amounts or total proportions.

[0026] According to the invention, the term "polymer system" refers to both a single polymer and a mixture of two or more different polymers. In accordance with the expert's understanding, a "polymer" or "a single polymer" is understood not only to refer to a single macromolecule, but also to a multitude of macromolecules that originate from one and the same polymerization process and have a specific molecular weight distribution among themselves.

[0027] The polymer system resulting from the process according to the invention exists in at least two phases. A person skilled in the art understands this to mean that one phase is rich in one component of the polymer system, for example polymer A, or consists essentially of this component, and the other phase is rich in another component, for example polymer B, or consists essentially of this component. The presence of small amounts of one component in the other, which does not preclude the formation of multiphases, is considered irrelevant. If the polymer system resulting from the process according to the invention has more than two phases, the above applies accordingly to all of these phases.

[0028] The phase separation is particularly preferably realized in such a way that discrete regions (“domains”) that are rich in polymer A or polymer B - i.e., are essentially formed from polymer A or polymer B - are present in a continuous matrix that is rich in the other polymer - i.e., is essentially formed from the other polymer. A polymer system resulting from the process according to the invention is considered to be present in at least two phases in particular if at least one of the following criteria a) - c) is met: a) Phase boundaries can be identified in a height profile analysis or an analysis of the Young's modulus of an atomic force microscopy (AFM) image of the polymer system. b) At least two independent glass transition temperatures are obtained from a differential scanning calorimetry (DSC) measurement carried out on the polymer system.c) At least two tan δ maxima are obtained from a dynamic mechanical analysis (DMA) performed on the polymer system.

[0029] According to the invention, the polymer system present in at least two phases also comprises a microphase-separated polymer system, i.e. a polymer system in which the discontinuous phase is present in microscopically fine distribution.

[0030] The process according to the invention comprises a step a) in which the polymerization of a monomer composition I which comprises at least 80% by weight, based on the total weight of the monomer composition I, of one or more monomers selected from the group consisting of methacrylic acid esters, methacrylamides and monomers having at least one polymerizable vinyl group, to form a polymer A.

[0031] The monomer composition I preferably comprises one or more monomers selected from the group consisting of methacrylic acid esters, methacrylamides, and monomers having at least one polymerizable vinyl group to an extent of at least 85% by weight, more preferably at least 90% by weight, particularly preferably at least 95% by weight, in particular at least 98% by weight. Most preferably, the monomer composition I exclusively comprises one or more monomers selected from the group consisting of methacrylic acid esters, methacrylamides, and monomers having at least one polymerizable vinyl group.

[0032] The polymerization of step a) can, in principle, be carried out in any desired manner. It is preferably carried out in a reactor, in particular in a reactor designed for processing highly viscous materials, or in a closed shell; more preferably, it is carried out in a planetary mixer or in a closed shell.

[0033] The polymerization of step a) is also preferably carried out in the absence of solvent. Solvent concentrations in very small ranges, e.g., resulting from production residues or in the range of the ubiquitous concentration, are considered irrelevant.

[0034] The polymer A resulting from the polymerization of step a) is preferably a polymer block from which or to which at least one further, distinguishable polymer block can be polymerized.

[0035] The process according to the invention comprises a step b) in which, in the presence of the polymer A, the polymerization of a monomer composition II which comprises at least 80% by weight, based on the total weight of the monomer composition I, one or more monomers selected from the group consisting of methacrylic acid esters, methacrylamides and monomers having at least one polymerizable vinyl group, wherein the monomer composition II differs from those of the monomer composition I in at least 50% by weight of its monomers, to a polymer B to obtain a polymer system comprising the polymers A and B which is present in at least two phases.

[0036] The monomer composition II preferably comprises one or more monomers selected from the group consisting of methacrylic acid esters, methacrylamides, and monomers having at least one polymerizable vinyl group to an extent of at least 85% by weight, more preferably at least 90% by weight, particularly preferably at least 95% by weight, in particular at least 98% by weight. Most preferably, the monomer composition II exclusively comprises one or more monomers selected from the group consisting of methacrylic acid esters, methacrylamides, and monomers having at least one polymerizable vinyl group.

[0037] According to the invention, the polymerization of step b) takes place in a closed shell. This is understood to mean any system, in principle, whose design does not interfere with the polymerization process and which spatially delimits and completely surrounds the composition to be polymerized or in the process of polymerization, at least limiting, and preferably preventing, the passage of at least air, water, and the enclosed monomers. The closed shell is preferably elastic.

[0038] The material of the closed shell is preferably selected from the group consisting of ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, polyethylene, polypropylene, polybutadiene, ionomer films, and mixtures thereof; more preferably, it is selected from polyethylene, ethylene-vinyl acetate copolymers, and mixtures thereof. The thickness of the material of the closed shell is preferably 30 to 100 μm, more preferably 35 to 70 μm, in particular 40 to 60 μm. The thickness of a closed shell filled with the materials to be polymerized is preferably 2 to 22 mm, more preferably 5 to 21 mm, in particular 7 to 20 mm. The materials mentioned are not critical for initiating polymerization by means of UV radiation.

[0039] The closed sleeve is produced, for example, by overlapping two film webs and heat-sealing them along the long sides and the bottom edge. The monomer mixture is then poured into the sleeve using a liquid form, fill, and seal machine. The sections are then sealed through the liquid level, creating several filled, closed sleeves that are then separated from each other.

[0040] The polymerization of step b) preferably takes place in the absence of solvent. Solvent concentrations in very small ranges, e.g., resulting from production residues or in the range of the ubiquitous concentration, are considered irrelevant. Particularly preferably, the process according to the invention is carried out entirely in the absence of solvents.

[0041] In a preferred embodiment of the process according to the invention, in step b), the polymer A is dissolved in the monomer composition II. This can in principle be done in any way known to the person skilled in the art, for example by stirring the polymer A into the monomer composition II. If the polymerization of step a) has taken place in a closed shell and the polymer A is thus present in the closed shell, the shell material

[0042] - destroyed at least to such an extent - preferably mechanically - that polymer A can be removed and introduced into monomer composition II, and then separated from polymer A or the mixture of polymer A and monomer composition II. It goes without saying that, in this context, monomer composition II is not to be considered a solvent in the above sense and therefore does not fall under the characteristic "in the absence of solvents."

[0043] Preferably, if the polymerization of step a) has taken place in a closed shell and the polymer A is thus present in the closed shell, the closed shell with the polymer A contained therein is introduced into a mixing apparatus, more preferably into a kneader; wherein the mixing apparatus already contains the monomer composition II or the monomer composition II is subsequently introduced into the mixing apparatus; the polymer A is brought into contact with the monomer composition II, more preferably dissolved in the monomer composition II, while destroying the closed shell; the shell material is separated from the mixture of polymer A and monomer composition II by means of filtration; and the mixture of polymer A and monomer composition II is introduced into a further closed shell.

[0044] Preferably, at least the polymerization in step b) of the process according to the invention is a controlled radical polymerization. A "controlled polymerization" is understood to mean a polymerization that allows at least control of the lengths of the resulting polymers or the resulting polymer blocks and the polymer architecture. Controlled radical polymerizations include, for example, atom transfer radical polymerization (ATRP), nitroxide / TEMPO-controlled polymerization, and the RAFT process.

[0045] In one embodiment of the invention, at least the polymerization in step b) of the process according to the invention is a RAFT polymerization. "RAFT polymerization" stands for "reversible addition-fragmentation chain transfer polymerization." This refers to a polymerization in which the reaction is controlled by reversible chain transfer reactions. An active, growing radical chain adds to a special regulator substance, the so-called RAFT agent, which is already linked to another chain and thus exists as a higher-molecular-weight RAFT agent (macro-RAFT agent). The addition of the active radical chain creates an intermediate that, due to its structure, has the potential to fragment in various directions. This process again produces a macro-RAFT agent and an active radical chain available for propagation, although the latter does not necessarily have to correspond to the previously active radical chain.In this way, the propagation probability is evenly distributed across all chains, resulting in a narrow molecular weight distribution.

[0046] In this embodiment, the polymerization of step a) is also preferably a controlled radical polymerization, particularly preferably a RAFT polymerization.

[0047] Regardless of the specific embodiment, the polymerization in step a) is preferably a radical polymerization, i.e., it is initiated by a radical-forming substance and then proceeds via a radical propagating by monomer addition. Radical formation and thus polymerization in step a) are preferably initiated by radiation, particularly preferably by UV radiation. In step b), radical formation and thus polymerization are also preferably initiated by radiation, particularly preferably by UV radiation.

[0048] In accordance with the above, at least the polymerization in step b) is preferably carried out in the presence of at least one regulator substance containing at least one sequence -SC(=X)-, in which X represents S, O, or NR', where R' represents an organic radical. More preferably, the polymerization in step a) is also carried out in the presence of such a regulator substance.

[0049] The regulator substance containing at least one sequence -SC(=X)- is preferably selected from the group consisting of

[0050] Dithioesters, i.e. compounds of the general structure (1)

[0051] (1 );

[0052] Dithiocarbonates, i.e. compounds of the general structure (2)

[0053] (2); xanthates, i.e. compounds of the general structure (3)

[0054] (3);

[0055] Dithiocarbamates, i.e. compounds of the general structure (4)

[0056] (4);

[0057] Trithiocarbonates, i.e. compounds of the general structure (5)

[0058] (5); and

[0059] Imido-dithiocarbonates, i.e. compounds of the general structure (6) wherein in the general structures (1) to (6), the substituents R each independently represent an organic or inorganic, preferably an organic, radical. In particular, at least one substituent R in the general structures (1) to (6) comprises a polymer chain formed during the polymerization in the relevant step. The regulator substance particularly preferably contains at least one sequence -SC(=X)- selected from trithiocarbonates and xanthates; in the above sense, therefore, preferably from compounds according to the general structures (3) and (5).

[0060] Very particularly preferably, the regulator substance containing at least one sequence -S- C(X)- in its original state, i.e. still without encompassed growing polymer chains, is selected from the group consisting of dibenzyl trithiocarbonate, O-ethyl-S-(1-methyloxycarbonyl)ethyl xanthate, 1,4-phenylenebis(methylene)didodecyl tricarbonotrithioate, 2,2'-[carbonothioylbis(thio)]bis[2-methylpropanoic acid] and 4-cyano-4-

[0061] (((dodecylthio)carbonothioyl)thio)pentanoic acid.

[0062] In one embodiment of the process according to the invention, at least the polymerization in step b) is carried out in the presence of at least one regulator substance containing at least one sequence -SC(=X)-, wherein X is S, O or NR', where R' is an organic radical, and is initiated by at least one radical-forming photoinitiator present alongside the at least one regulator substance. A "photoinitiator" is understood to be a substance that forms radical species under the influence of light of certain wavelengths, usually at least under the action of UV radiation, optionally also UV radiation in the wavelength range of visible light (approx. 300 - 500 nm). The at least one radical-forming photoinitiator is preferably selected from the group consisting of 1-hydroxycyclohexylphenyl ketone and 2,2-dimethoxy-2-acetophenone.

[0063] Preferably, the polymerization in step a) is also carried out in the presence of at least one regulator substance containing at least one sequence -SC(=X)-, wherein X is S, O or NR', where R' is an organic radical, and initiated by at least one photoinitiator which forms radicals and is present in addition to the at least one regulator substance.

[0064] However, within the scope of the process according to the invention, it is also possible for the polymerization in one or both of steps a) and b) to be carried out in the presence of at least one regulator substance containing at least one sequence -SC(=X)-, wherein X stands for S, O or NR', where R' stands for an organic radical, and for the regulator substance itself to act as a polymerization initiator. In this case, the polymerization can be initiated without an additional initiator and can be carried out overall without the use of an additional polymerization initiator. Such regulator substances are also known to those skilled in the art under the name "initiator" since they combine the functions of an initiator, transfer agent and terminator. From this perspective, the regulator substance is preferably a trithiocarbonate.

[0065] A preferred subject matter of the invention is a process for producing a polymer system which is present in at least two phases, comprising the following steps: a) UV-initiated, radical polymerization of a monomer composition I comprising a total of at least 80% by weight of one or more monomers selected from the group consisting of methacrylic acid esters, methacrylamides and monomers having at least one polymerizable vinyl group to form a polymer A; b) UV-initiated, radical polymerization of a monomer composition II comprising a total of at least 80% by weight of one or more monomers selected from the group consisting of methacrylic acid esters, methacrylamides and monomers having at least one polymerizable vinyl group, wherein the monomer composition II comprises at least 50% by weight of-% of its monomers differs from those of the monomer composition I, in the presence of the polymer A to form a polymer B to obtain a polymer system present in at least two phases comprising the polymers A and B; characterized in that step b) takes place in a closed shell.

[0066] Even more preferred is a process for producing a polymer system present in at least two phases, comprising the following steps: a) UV-initiated RAFT polymerization of a monomer composition I comprising a total of at least 80% by weight of one or more monomers selected from the group consisting of methacrylic acid esters, methacrylamides and monomers having at least one polymerizable vinyl group to form a polymer A; b) UV-initiated, radical polymerization of a monomer composition II comprising a total of at least 80% by weight of one or more monomers selected from the group consisting of methacrylic acid esters, methacrylamides and monomers having at least one polymerizable vinyl group, wherein the monomer composition II comprises at least 50% by weight of-% of its monomers differs from those of the monomer composition I, in the presence of the polymer A to form a polymer B to obtain a polymer system present in at least two phases comprising the polymers A and B; characterized in that step b) takes place in a closed shell.

[0067] The process according to the invention is intended to result in a polymer system consisting of at least two phases. Another aim of the invention was to provide the two- or multi-phase polymer system with the highest possible cohesion. Therefore, it seemed important to consider these and, if necessary, other properties of the final polymer system when selecting the monomers used in the two polymerization steps.

[0068] Against this background, in one embodiment of the invention, one of the monomer compositions I and II comprises a total of at least 50 wt. %, more preferably a total of at least 60 wt. %, in particular a total of at least 75 wt. % of one or more monomers having a glass transition temperature of the homopolymer in question of <0 °C, more preferably of <-10 °C, in particular of <-20 °C; and the respective other of the monomer compositions I and II comprises a total of at least 60 wt. %, more preferably a total of at least 70 wt. %, in particular a total of at least 80 wt. % of one or more monomers having a glass transition temperature of the homopolymer in question of >50 °C, more preferably of >75 °C, in particular of >100 °C.

[0069] In a continuation of this embodiment, one of the monomer compositions I and II preferably comprises at least 50% by weight in total, more preferably at least 60% by weight in total, in particular at least 75% by weight in total, of one or more monomers selected from the group consisting of ethyl acrylate, n-butyl acrylate, isobutyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-heptyl acrylate, n-heptyl acrylate, 2-ethylhexyl acrylate, 2-octyl acrylate, n-octyl acrylate, isooctyl acrylate, n-nonyl acrylate, isononyl acrylate, n-decyl acrylate, isodecyl acrylate, 2-[[(butylamino)carbonyl]oxy]ethyl acrylate, 2-cyanoethyl acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, phenoxyethyl acrylate, iso-stearyl acrylate, docosyl acrylate, and 2-[2-(2-methoxyethoxy)ethoxy]ethyl acrylate; and the other of the monomer compositions I and II comprises a total of at least 60% by weight, more preferably a total of at least 70% by weight,insbesondere zu insgesamt mindestens 80 Gew.-% ein oder mehrere Monomere ausgewählt aus der Gruppe bestehend aus Isobornylacrylat, Norbornylacrylat, Benzylacrylat, 3,3,5- T rimethylcyclohexylacrylat, Cyclohexylacrylat, 4-[(6-Acryloyloxy)hexyloxy]4‘-cyanobiphenyl, N-Succinimidylacrylat, 1 -Ethylcyclopentylacrylat, N-tert-Octylacrylamid, N-tert-Butylacrylamid, Dimethylacrylamid, Diethylacrylamid, N-iso-Propylacrylamid, Acrylamid, N-[3- (Dimethylamino)propyl]acrylamid, Diacetonacrylamid, N-(Butoxymethyl)acrylamid, N- Phenylacrylamid, N-[2-(Dimethylamino)ethyl]acrylamid, N-[2-(Diethylamino)ethyl]acrylamid, Methylmethacrylat, Ethylmethacrylat, Cyclohexylmethacrylat, Benzylmethacrylat, Isobornylmethacrylat, Glycerolformalmethacrylat, 2-Dimethylaminoethylmethacrylat, Phenoxyethylmethacrylat, 9-Anthrylmethylmethacrylat, 2-Ethyl-2-adamantylmethacrylat, 2- (Acetoacetyloxy)ethylmethacrylat, 2-lsopropyl-2-methacryloyloxyadamantan, iso- Propylmethacrylat, iso-Butylmethacrylat,tert-Butylmethacrylat, Furfurylmethacrylat, 2- Methacryloyloxy-2-methyladamantan, 2-Morpholinoethylmethacrylat, Phenylmethacrylat, N- Succinimidylmethacrylat, 2-(tert-Butylamino)ethylmethacrylat, 2-Cyclohexylpropan-2-yl- methacrylat, 1 -Adamantylmethacrylat, 1 -Methylcyclopentylmethacrylat, 3- Dimethylaminopropylmethacrylamid, N-tert-Butylmethacrylamid, N-,

[0070] (Methoxymethyl)methacrylamid, N,N-Dimethylmethacrylamid, Methacrylamid, N- Phenylmethacrylamid, N,N-Dimethylmethacrylamid, N-iso-Propylmethacrylamid, N-

[0071] Vinylformamid, N-Vinylpyrrolidon, N-Vinylcaprolactam, N-Vinylcrbazol, N-Vinylimidazol, Vinylmethyloxazolidinon und N-Vinyl-N-methylacetamid.

[0072] More preferably, one of the monomer compositions I and II comprises a total of at least 50% by weight, more preferably a total of at least 60% by weight, in particular a total of at least 75% by weight of one or more monomers selected from the group consisting of n-butyl acrylate, iso-amyl acrylate, n-heptyl acrylate, 2-ethylhexyl acrylate, 2-octyl acrylate, iso-octyl acrylate, n-octyl acrylate, n-decyl acrylate, iso-decyl acrylate and lauryl acrylate; and the respective other of the monomer compositions I and II comprises a total of at least 60 wt.%, more preferably a total of at least 70 wt.%, in particular a total of at least 80 wt.% of one or more monomers selected from the group consisting of isobornyl acrylate, norbornyl acrylate, tert-butyl methacrylate, benzyl acrylate, N-isopropylacrylamide, N-tert-octylacrylamide, N-tert-butylacrylamide and dimethylacrylamide.

[0073] In a further development of this embodiment, one of the monomer compositions I and II preferably comprises a total of at least 50% by weight, more preferably a total of at least 60% by weight, in particular a total of at least 75% by weight of one or more monomers selected from the group consisting of ethyl acrylate, n-butyl acrylate, iso-butyl acrylate, iso-amyl acrylate, n-hexyl acrylate, n-heptyl acrylate, 2-heptyl acrylate, 2-ethylhexyl acrylate, 2-octyl acrylate, n-octyl acrylate, iso-octyl acrylate, n-nonyl acrylate, iso-nonyl acrylate, n-decyl acrylate, iso-decyl acrylate, 2-

[0074] [[(Butylamino)carbonyl]oxy]ethyl acrylate, 2-cyanoethyl acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, phenoxyethyl acrylate, iso-stearyl acrylate, docosyl acrylate, and 2-[2-(2-methoxyethoxy)ethoxy]ethyl acrylate; to a total of not more than 35 wt.%, more preferably to a total of not more than 25 wt.%, in particular to a total of not more than 20 wt.% of one or more monomers selected from the group consisting of isobornyl acrylate, norbornyl acrylate, methyl methacrylate, dimethylacrylamide, diethylacrylamide, 4-tert-butylcyclohexyl acrylate, tert-butyl acrylate, tert-butyl methacrylate, cyclohexyl methacrylate and cyclohexyl acrylate; to a total of not more than 10 wt.% of one or more functionalized monomers; and the other of the monomer compositions I and II comprises a total of at least 60 wt.%, more preferably a total of at least 70 wt.%, in particular a total of at least 80 wt.-% one or more monomers selected from the group consisting of isobornyl acrylate, norbornyl acrylate, benzyl acrylate, 3,3,5- trimethylcyclohexyl acrylate, cyclohexyl acrylate, , 4-[(6-acryloyloxy)hexyloxy]4'-cyanobiphenyl, N-succinimidyl acrylate, 1-ethylcyclopentyl acrylate, N-tert-octylacrylamide, N-tert-butylacrylamide, dimethylacrylamide, diethylacrylamide, N-iso-propylacrylamide, , N-[3-.

[0075] (Dimethylamino)propyl]acrylamid, Diacetonacrylamid, N-(Butoxymethyl)acrylamid, N- Phenylacrylamid, N-[2-(Dimethylamino)ethyl]acrylamid, N-[2-(Diethylamino)ethyl]acrylamid, Methylmethacrylat, Ethylmethacrylat, Cyclohexylmethacrylat, Benzylmethacrylat, Isobornylmethacrylat, Glycerolformalmethacrylat, 2-Dimethylaminoethylmethacrylat, Phenoxyethylmethacrylat, 9-Anthrylmethylmethacrylat, 2-Ethyl-2-adamantylmethacrylat, 2- (Acetoacetyloxy)ethylmethacrylat, 2-lsopropyl-2-methacryloyloxyadamantan, iso- Propylmethacrylat, iso-Butylmethacrylat, tert-Butylmethacrylat, Furfurylmethacrylat, 2- Methacryloyloxy-2-methyladamantan, 2-Morpholinoethylmethacrylat, Phenylmethacrylat, N- Succinimidylmethacrylat, 2-(tert-Butylamino)ethylmethacrylat, 2-Cyclohexylpropan-2-yl- methacrylat, 1 -Adamantylmethacrylat, 1 -Methylcyclopentylmethacrylat, 3- Dimethylaminopropylmethacrylamid, N-tert-Butylmethacrylamid, N-

[0076] (Methoxymethyl)methacrylamid, N,N-Dimethylmethacrylamid, , N-Phenylmethacrylamid, N,N- Dimethylmethacrylamid, N-iso-Propylmethacrylamid, N-Vinylformamid, N-Vinylpyrrolidon, N- Vinylcaprolactam, N-Vinylcrbazol, N-Vinylimidazol, Vinylmethyloxazolidinon und N-Vinyl-N- methylacetamid; sowie zu insgesamt maximal 10 Gew.-% one or more functionalized monomers, wherein the functionalized monomers are selected from the group consisting of 1 - acryloyloxy-3-hydroxyadamantane, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 2-hydroxy-3-phenoxypropyl methacrylate, 4-hydroxyethyl acrylamide, acrylic acid, methacrylic acid, 2-acryloyloxyethyl succinate, methacryloxyethyl succinate, sulfoethyl methacrylate, acrylamide, methacrylamide, glycidyl acrylate, glycidyl methacrylate, 3,4-epoxycyclohexyl methyl acrylate, 3,4-epoxycyclohexyl methyl methacrylate, 4-hydroxybutyl acrylate glycidyl ether, 4- Hydroxybutylmethacrylate glycidyl ether, isocyanatoethyl acrylate, isocyanatoethyl methacrylate, 2-[2-(methacryloyloxy)ethyloxy]ethyl isocyanate, 2-[2-(acryloyloxy)ethyloxy]ethyl isocyanate and a,a-dimethyl-m-isopropenylbenzyl isocyanate.

[0077] In particular, one of the monomer compositions I and II comprises a total of at least 50% by weight, more preferably a total of at least 60% by weight, in particular a total of at least 75% by weight of one or more monomers selected from the group consisting of n-butyl acrylate, iso-amyl acrylate, n-heptyl acrylate, 2-ethylhexyl acrylate, 2-octyl acrylate, iso-octyl acrylate, n-octyl acrylate, n-decyl acrylate and isodecyl acrylate; a total of not more than 35% by weight, more preferably a total of not more than 25% by weight, in particular a total of not more than 20% by weight of one or more monomers selected from the group consisting of isobornyl acrylate, norbornyl acrylate, methyl methacrylate, dimethylacrylamide and a total of not more than 10% by weight.-% of one or more monomers selected from the group consisting of acrylic acid, methacrylic acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 3,4-epoxycyclohexyl methyl acrylate, 3,4-epoxycyclohexyl methyl methacrylate, glycidyl acrylate and glycidyl methacrylate; and the respective other of the monomer compositions I and II comprises a total of at least 60 wt.%, more preferably a total of at least 70 wt.%, in particular a total of at least 80 wt.% of one or more monomers selected from the group consisting of isobornyl acrylate, norbornyl acrylate, tert-butyl methacrylate, benzyl acrylate, N-isopropylacrylamide, N-tert-octylacrylamide, N-tert-butylacrylamide and dimethylacrylamide; and a total of not more than 10 wt.-% one or more monomers selected from the group consisting of acrylic acid, methacrylic acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 3,4-epoxycyclohexyl methyl acrylate, 3,4-epoxycyclohexyl methyl methacrylate, glycidyl acrylate and glycidyl methacrylate.

[0078] In a specific embodiment of the process according to the invention, at least the monomer composition II is free from methyl methacrylate; more preferably, it is free from methacrylic acid esters and methacrylamides; in particular, it is free from any methacrylic compounds.

[0079] Preferably, the monomer composition I is also free from methyl methacrylate; more preferably, it is free from methacrylic acid esters and methacrylamides; in particular, it is free from any methacrylic compounds.

[0080] As has been shown, the exclusion of the above-mentioned compounds has a beneficial effect on the polymerization rate.

[0081] The invention further relates to a polymer system which is present in at least two phases and in a closed shell and which is obtainable by a process according to the invention.

[0082] The polymer system resulting from the process according to the invention is preferably a block copolymer. The polymer blocks of this block copolymer are preferably formed by polymers A and B. More preferably, the polymer system resulting from the process according to the invention is a triblock copolymer, in particular a triblock copolymer of the form ABA or BAB, where A and B represent polymers A and B.

[0083] The polymer system resulting from the process according to the invention is also preferably an elastomer.

[0084] The invention further provides for the use of a polymer system according to the invention as at least one polymer component in an extrusion process for producing an adhesive, in particular a pressure-sensitive adhesive. A pressure-sensitive adhesive, as understood by those skilled in the art, is an adhesive that has pressure-sensitive adhesive properties, i.e., the ability to form a permanent bond to a substrate even under relatively light pressure. Such adhesives or pressure-sensitive adhesive tapes are generally permanently tacky even at room temperature, meaning they exhibit a certain viscosity and tackiness, so that they wet the surface of a substrate even under light pressure.Without wishing to be bound by this theory, it is often assumed that a pressure-sensitive adhesive can be viewed as an extremely viscous liquid with an elastic component, which consequently exhibits characteristic viscoelastic properties that lead to the permanent inherent tack and pressure-sensitive adhesive capacity described above. It is assumed that, upon mechanical deformation, pressure-sensitive adhesives undergo both viscous flow processes and the build-up of elastic restoring forces. The partial viscous flow serves to achieve adhesion, while the partial elastic restoring forces are particularly necessary to achieve cohesion. The relationships between rheology and pressure-sensitive tack are known in the art and are described, for example, in "Satas, Handbook of Pressure Sensitive Adhesives Technology", Third Edition, (1999), pages 153 to 203.To characterize the degree of elastic and viscous components, the storage modulus (G') and the loss modulus (G") are usually used, which can be determined by means of dynamic mechanical analysis (DMA), for example using a rheometer. For the purposes of the present invention, an adhesive is preferably understood to be pressure-sensitive and thus a pressure-sensitive adhesive if, at a temperature of 23°C in the deformation frequency range from 10° to 10 1 rad / sec G' and G“ each at least partly in the range of 10 3 up to 10 7 Pa lie.

[0085] To produce an adhesive, in particular a pressure-sensitive adhesive, in an extrusion process, the polymer system of the invention present in the closed shell is heated in the extruder to a temperature at which the shell material melts and can thus be homogeneously incorporated into the polymer system. As has been shown, the influence of the shell material on the properties of the adhesives produced with the polymer system of the invention lies below the limit of technical relevance. The polymer system is heated to such an extent that it is deformable, in particular flowable. As has been established, the specific polymer systems of the present invention frequently have lower viscosities and thus better deformability and flowability than conventional polymers used, in particular, for the production of pressure-sensitive adhesives.The polymer system according to the invention can thus be processed into an adhesive in an extruder under the influence of heat and shear, optionally also with the incorporation of additional components, and finally molded. The temperatures typically used do not lead to the decomposition of the regulator substances incorporated into the polymer frameworks and thus also do not lead to polymer degradation. A key advantage of the invention is that prior to processing the polymer systems in the extruder, there is no need to remove solvents, which regularly leads to the degradation processes just described.

[0086] Further process steps such as mixing with additives, filtration, or degassing can also take place in the extruder. The resulting adhesive, particularly the pressure-sensitive adhesive, can be formed into a desired layer shape, for example, using a calender on a carrier or release liner.

[0087] During the processing of the polymer system into an adhesive, in particular a pressure-sensitive adhesive, the polymer system can be mixed with additional components. These additional components can be selected from the group consisting of additional polymers; adhesive strength-enhancing resins; fillers, for example electrically conductive fillers, thermally conductive fillers, and the like; flame retardants, for example ammonium polyphosphate and its derivatives; foaming agents; anti-aging agents; light stabilizers; plasticizers, and compounding particles.

[0088] The invention further provides a composition for producing a pressure-sensitive adhesive comprising a polymer system according to the invention, wherein the polymer system is no longer present in the closed shell and the composition is free of crosslinkers. A significant advantage of the present invention is that polymer systems produced according to the invention often already possess such intrinsic cohesion that they can serve as the basis for pressure-sensitive adhesives without the need for further crosslinking. They thus differ from conventional polymer systems used for producing pressure-sensitive adhesives based on monomers with functionalized vinyl groups, which are generally crosslinked by means of high-energy radiation or thermally to achieve sufficient cohesion buildup. Examples

[0089] Measurement and testing methods:

[0090] Method 1 - Determination of the glass transition temperature of polymers

[0091] The static glass transition temperature of the polymers was determined using dynamic scanning calorimetry (DSC). For this purpose, 5 mg of an untreated sample of the polymer in question was weighed into an aluminum crucible (volume 25 pl) and sealed with a perforated lid. A DSC 204 F1 from Netzsch was used for the measurement. The measurement was carried out under nitrogen for inerting. The sample was first cooled to -150 °C, then heated at a heating rate of 10 K / min to +150 °C and cooled again to -150 °C. The subsequent second heating curve was again run at 10 K / min and the change in heat capacity was recorded. Glass transitions are detected as steps in the thermogram (heat flow-temperature diagram, see Figure 1).

[0092] The glass transition temperature T g is obtained as follows (see Figure 1 ):

[0093] The linear sections of the measurement curve before and after the step are extended in the direction of increasing (area before the step) or decreasing (area after the step) temperatures (extension lines © and ®). In the step region, a best-fit line ® is placed parallel to the ordinate so that it intersects the two extension lines, creating two areas ® and @ (between the extension line, the best-fit line, and the measurement curve) of equal area. The intersection point of the best-fit line positioned in this way with the measurement curve yields the glass transition temperature.

[0094] Method 2 - Determination of molecular masses

[0095] The weight-average molecular weight M wThe measurements in this document refer to the conventional method of determination by gel permeation chromatography (GPC). The determination is carried out on 100 μl of a clear-filtered sample (sample concentration 3 g / l). Tetrahydrofuran is used as the eluent. The measurement is carried out at 25 °C.

[0096] The guard column is a column type PSS-SDV, 5 pm, 10 3 Ä, 8.0 mm * 50 mm (information here and below in the order: type, particle size, inner diameter * length; 1 Ä = 10 -1 ° m). For separation, a combination of columns of the type PSS SDV, 5 pm, 10 3 Ä and 10 5 Ä and 10 6 Ä with 8.0 mm * 300 mm each (columns from Agilent; detection by means of differential refractometer PSS SECcurity 2). The flow rate is 1.0 ml per minute. Calibration is performed using the commercially available ReadyCal Poly(styrene) high kit from Agilent. This is universally converted to polymethyl methacrylate (PMMA) using the Mark-Houwink parameters K and alpha, so that the data are expressed in PMMA mass equivalents.

[0097] The polydispersity (PDI) is determined in a manner known to the person skilled in the art as the quotient of the weight-average and number-average molecular weight.

[0098] Method 3 - Dynamic Mechanical Analysis (DMA)

[0099] G' and G" are determined using a rheometer. The material under test is subjected to a sinusoidal oscillating shear stress in a plate-on-plate arrangement. Shear stress-controlled devices measure the deformation as a function of time and the temporal offset of this deformation relative to the application of the shear stress. This temporal offset is referred to as the phase angle δ.

[0100] The storage modulus G' is defined as follows: G' = (i / y) * cos(ö) (T = shear stress, y = deformation, ö = phase angle = phase shift between shear stress and deformation vector). The definition of the loss modulus G" is: G" = (i / y) * sin(ö) (T = shear stress, y = deformation, ö = phase angle = phase shift between shear stress and deformation vector). tan ö = G“ / G'.

[0101] Device: deformation-controlled rheometer (ARES), plate-plate, o 25 mm

[0102] Deformation: 1%

[0103] Frequency: 10 rad / s.

[0104] Method 4 - Determination of static shear strength (shear life)

[0105] The shear strength is a measure of the internal strength of the adhesive and was tested in the so-called static shear test as follows: The test was carried out under standard climate (23 °C, 50% relative humidity) using a weight of 1 kg. A 1.3 cm wide strip of the sample (50 μm polymer layer on 36 μm etched PET film) was bonded to a polished steel plate over a length of 2 cm by rolling over it with a 2 kg roller (twice back and forth). The platelets were equilibrated for 30 minutes under test conditions, but without load. The test weight (1 kg) was then attached so that a shear stress was applied parallel to the bonding surface, and the time until the bond failed was measured. The measurement result is given in minutes. The median of three individual measurements is given.

[0106] Preparing the cover material:

[0107] Two sheets of an ethylene-vinyl acetate copolymer film (5% VA) were superimposed and heat-sealed at three of the four side edges to form a rectangular bag with a width of 10 cm and a length of 20 cm.

[0108] Example 1, step a) - Polymer 1 A

[0109] To prepare polymer 1A, 120 g of a reaction mixture consisting of 99.2 wt.% IBOA (isobornyl acrylate), 0.5 wt.% DBTTC (dibenzyl trithiocarbonate), and 0.3 wt.% Irgacure® 184 (1-hydroxycyclohexyl phenyl ketone) were filled into the bag prepared as above on a liquid form, fill, and seal machine. The reaction mixture was rendered inert by passing nitrogen through it for 30 minutes. The bag was then sealed at the top in the transverse direction. The thickness of the filled bag was 8 mm.

[0110] The bag was placed in a water bath heated to 20 °C so that it was completely surrounded by water. A Heraeus Semray LIV2000 LED 365 nm UV lamp was placed on the top and bottom at a distance of 23 cm. It was illuminated for 10 minutes with an intensity of 10 mW / cm resulting from the described setup. 2 irradiated.

[0111] The weight-average molecular weight (M w ) and the polydispersity (PDI) of the prepared polymer 1 A are given in Table 1.

[0112] Example 1, step b) - Polymer 1 B

[0113] Polymer 1A from step a) was mechanically separated from the bag material. Subsequently, 17 wt.% of polymer 1A was dissolved in 83 wt.% n-butyl acrylate. The resulting reaction mixture was filled into another bag prepared as described above and inertized for 30 minutes by passing nitrogen through it. The bag was sealed at the top with the monomer.

[0114] The bag contents were irradiated in the same way as in step a).

[0115] The weight-average molecular weight (M w ) and the polydispersity (PDI) of the prepared polymer 1B are given in Table 1. Example 2, Step a) - Polymer 2A

[0116] To prepare polymer 2A, 120 g of a reaction mixture consisting of 99.2 wt.% nBA (n-butyl acrylate), 0.5 wt.% BM1812® (phenylenebis(methylene)didodecyl dicarbonotrithioate), and 0.3 wt.% Irgacure® 184 (1-hydroxycyclohexyl phenyl ketone) were filled into a bag prepared as above. The reaction mixture was rendered inert by passing nitrogen through it for 30 minutes. The bag was then sealed at the top in the transverse direction.

[0117] The bag contents were irradiated in the same manner as in Example 1, step a).

[0118] The molar mass (M w ) and the polydispersity (PDI) of the prepared polymer 2A are given in Table 1.

[0119] Example 2, step b) - Polymer 2B

[0120] Polymer 2A was mechanically separated from the bag material. Subsequently, 83 wt.% of Polymer 2A was dissolved in 17 wt.% IBOA (isobornyl acrylate). The resulting reaction mixture was filled into another bag prepared as described above and inerted for 30 minutes by passing nitrogen through it. The bag was sealed at the top.

[0121] The bag contents were irradiated in the same manner as in Example 1, step a).

[0122] The weight-average molecular weight (M w ) and the polydispersity (PDI) of the prepared polymer 2B are given in Table 1.

[0123] Example 3, step b) - Polymer 3B

[0124] Polymer A from Example 1, step a) was mechanically separated from the bag material. Subsequently, 25 wt.% of this polymer was dissolved in 75 wt.% LA1214F® (a mixture of lauryl acrylate and myristyl acrylate). The resulting reaction mixture was filled into another bag prepared as described above and rendered inert for 30 minutes by passing nitrogen through it. The bag was sealed at the top.

[0125] The bag contents were irradiated in the same manner as in Example 1, step a).

[0126] The weight-average molecular weight (M w ) and the polydispersity (PDI) of the prepared polymer 3B are listed in Table 1.

[0127] Example 4 (Comparative Example) To prepare polymer 4, 120 g of a reaction mixture consisting of 82.2 wt.% nBA (n-butyl acrylate), 17 wt.% iBOA (isobornyl acrylate), 0.11 wt.% DBTTC (dibenzyl trithiocarbonate), and 0.3 wt.% Irgacure® 184 (1-hydroxycyclohexyl phenyl ketone) were filled into a bag prepared as above. The reaction mixture was rendered inert by passing nitrogen through it for 30 minutes. The bag was then sealed at the top in the transverse direction.

[0128] The bag contents were irradiated in the same manner as in Example 1, step a).

[0129] The molar mass (M w ) and the polydispersity (PDI) of the prepared polymer 4 are given in Table 1.

[0130] Table 1 : Weight-average molecular weight, polydispersity and shear stability time of the polymers

Claims

Patent claims 1. A process for producing a polymer system which is present in at least two phases, comprising the steps of: a) polymerising a monomer composition I comprising, to a total of at least 80% by weight, one or more monomers selected from the group consisting of methacrylic acid esters, methacrylamides and monomers having at least one polymerisable vinyl group to form a polymer A; and b) polymerising a monomer composition II comprising, to a total of at least 80% by weight, one or more monomers selected from the group consisting of methacrylic acid esters, methacrylamides and monomers having at least one polymerisable vinyl group, wherein the monomer composition II is present in at least 50% by weight.-% of its monomers differs from those of the monomer composition I, in the presence of the polymer A to a polymer B to obtain a polymer system present in at least two phases comprising the polymers A and B; characterized in that step b) takes place in a closed shell.

2. Process according to claim 1, characterized in that at least the polymerization in step b) is a controlled radical polymerization.

3. Process according to one of claims 1 and 2, characterized in that at least the polymerization in step b) is carried out in the presence of at least one regulator substance containing at least one sequence -SC(=X)-, in which X represents S, O or NR', where R' represents an organic radical.

4. The method according to claim 3, characterized in that the regulator substance is selected from the group consisting of trithiocarbonates and xanthates.

5. Process according to one of the preceding claims, characterized in that the material of the closed envelope is selected from the group consisting of ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, polyethylene, polypropylene, polybutadiene and ionomer films.

6. Process according to one of the preceding claims, characterized in that in step b) the polymer A is dissolved in the monomer composition II.

7. Process according to one of the preceding claims, characterized in that the polymerization of step b) takes place in the absence of solvent.

8. A polymer system present in at least two phases and in a closed shell, obtainable by a process according to any one of the preceding claims.

9. Polymer system according to claim 8, characterized in that the Polymer system is a block copolymer.

10. Polymer system according to one of claims 8 and 9, characterized in that the polymer system is an elastomer.

11. Use of a polymer system according to any one of claims 8 to 10 as at least one polymer component in an extrusion process for producing an adhesive.

12. A composition for producing a pressure-sensitive adhesive comprising a polymer system according to any one of claims 8 to 10, wherein the polymer system is no longer present in the closed shell and the composition is free of crosslinkers.

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