JP2012508309A - Method for producing telechelic polymer having bimodal molecular weight distribution - Google Patents

Abstract

  The present invention relates to a controlled polymerization process for producing telechelic polymers based on (meth) acrylates and having a bimodal molecular weight distribution, as well as its use as a binder in adhesives or sealants.

Description

  The present invention relates to a controlled polymerization process for producing telechelic polymers based on (meth) acrylates and having a bimodal molecular weight distribution, as well as its use as a binder in adhesives or sealants. Tailor-made copolymers with defined composition, chain length, molecular weight distribution, etc. are one broad area of research. A distinction is made in particular between gradient polymers and block polymers. Various applications are conceivable for such materials. Some of them are briefly introduced below.

  The polymers can be produced, for example, by ionic polymerization methods or by polycondensation or polyaddition. In these methods, there is no problem in the production of products with functionalized end groups. However, construction of an appropriate molecular weight is a problem.

  The polymer obtained by the free radical polymerization method clearly shows an index of molecular weight distribution exceeding 1.8. That is, in such a molecular weight distribution, inevitably very short-chain polymers and long-chain polymers are present in the entire product. Short polymer chains exhibit low viscosity in the melt or solution and high mobility in the polymer matrix compared to long chain components. This leads on the one hand to improved processability of such polymers and on the other hand to increased availability of polymer-bonded functional groups in the polymer material or coating. In contrast, long chain by-products lead to excessive thickening of the polymer melt or solution. The migration of such polymers in the matrix is also clearly reduced.

  However, a drawback of this type of binder produced by free radicals is the random distribution of functional groups in the polymer chain. Furthermore, it is not possible to synthesize a rigid / soft / rigid triblock structure by a free radical polymerization method or to synthesize individual polymer blocks with a narrow molecular weight distribution.

  As living polymerization methods or controlled polymerization methods, in addition to anionic polymerization or group transfer polymerization, modern methods of controlled radical polymerization, for example RAFT polymerization, are also suitable. The ATRP method (atom transfer radical polymerization) was decisively developed in the 1990s by Prof. Matyjazewski et al. 272, p.866). ATRP provides a narrowly distributed (homo) polymer with a molecular weight range of Mn = 10000 to 120,000 g / mol. A special advantage in this case is that the molecular weight can be controlled. As living polymerisation, it is further possible to properly construct polymer structures, for example random copolymer or block copolymer structures. The controlled radical method is also suitable for proper functionalization of vinyl polymers in particular. Of particular interest is the functionalization at the end of the chain (so-called telechelic polymer) or near the end of the chain. In contrast, in the case of radical polymerization, proper functionalization at the chain ends is almost impossible.

  Binders having a defined polymer design can be provided by controlled polymerization methods, for example polymerization methods in the form of atom transfer radical polymerization. For example, ABA triblock copolymers having an unfunctionalized B block and a functionalized outer A block are described. EP 1475397 describes such polymers having OH groups, WO2007 / 033877 is olefinic, WO2008 / 012116 has amine groups and DE102008002016, which has not yet been published, Those having a silyl group are described. However, all the polymers described in these documents have a very narrow molecular weight distribution.

  With respect to the so-called controlled polymerization methods described above, no method is described that can produce a polymer having a single molecular weight or a plurality of blocks having a molecular weight distribution of an appropriate width.

  One method that has already been established is the end group functionalization of poly (meth) acrylates with olefin groups and subsequent hydrosilylation of the groups. Such a method is described in particular in EP 1024153, EP 1085027, and EP 1153942. However, it is not a block copolymer and it has been demonstrated that the molecular weight distribution of the product is less than 1.6. Another disadvantage of such products for polymers with multi-functionalized outer blocks is that it is likely to obtain products that are not functionalized on one side. The low degree of functionalization obtained each time for the polymers according to the invention results in a low degree of crosslinking in the subsequent reaction, for example in the course of curing of the sealant composition, which impairs mechanical stability and chemical resistance. . In addition to telechelic polymers and block structures, ATRP synthesized (meth) acrylate copolymers with a random distribution and a narrow molecular weight distribution, for example silyl, are one alternative. The disadvantage of such binders is narrow cross-linking. Such binder systems also do not have the advantage that the polymer chains obtained in the system are particularly long or particularly short, based on the narrow molecular weight distribution.

Other methods besides ATRP are also used to synthesize functionalized polymer structures. Another related method is briefly described below. In so doing, a distinction is made between the product and the method. In this case the advantages of ATRP over other methods in particular become clear:
In the case of anionic polymerization, bimodality can occur. However, these polymerization methods can only produce specific functionalizations.

  For ATRP, a bimodal distribution for the system is described. However, the bimodality of these polymers is in each case caused on the one hand by the presence of block copolymers and on the other hand by the presence of unreacted macroinitiators. The disadvantage of this method is that it produces a product consisting of a mixture of two different polymer compositions.

Challenges A new stage of development is the telechelic polymers described below. A telechelic polymer is understood to be a polymer having exactly the same functional groups at both chain ends. In the sense of the present invention, this is a polymer having these functional groups in at least 75%, preferably at least 85% of the chain ends.

  The challenge was to provide a method for synthesizing telechelic polymers having a total polydispersity index of at least 1.8. In particular, it was an object to provide a method for synthesizing a telechelic polymer having a bimodal molecular weight distribution.

  In one embodiment of the present invention, it was an object to provide a method for synthesizing a telechelic triblock polymer of structure ABA composed of poly (meth) acrylate. In this case, these polymers are A blocks having a narrow molecular weight distribution of less than 1.6 and B blocks having a bimodal molecular weight distribution on the one hand with long polymer chains and on the other hand with particularly short polymer chains. Should consist of In particular, the B block having a bimodal molecular weight distribution is an ABA triblock copolymer having a polydispersity index of at least 1.8, wherein the ABA triblock copolymer has a total polydispersity of at least 1.8. There is a need for ABA triblock copolymers having B blocks with a sex index. The ABA triblock copolymer can then be equated with a pentablock copolymer of composition ACBCA or CABAC.

  In parallel, the object of the present invention was to provide a method for separating a transition metal complex from a polymer solution, which can be realized industrially by a functionalization method step. At the same time, the new method should be cheap and fast to implement. Another challenge was to achieve a low residual concentration of transition metal complex, already after the filtration step.

The above problems have been solved by providing a novel polymerization method based on atom transfer radical polymerization (ATRP). The problem has been solved in particular by adding the bifunctional initiator in several batches to the polymerization solution and interrupting the polymerization by adding an appropriate sulfur compound. In particular, the present invention provides a method for producing a (meth) acrylate polymer, characterized in that the (meth) acrylate polymer produced according to the present invention has a polydispersity index greater than 1.8. In this case, a polymer with a bimodal molecular weight distribution is produced by a method that splits the start in two.

  A bimodal molecular weight distribution of a polymer or a mixture of polymers, according to the invention, is a total molecular weight distribution consisting of two different individual molecular weight distributions with different average molecular weights Mn and Mw. And understand. In doing so, both molecular weight distributions may be completely separated from each other and overlap as long as they have two distinguishable maximums, or they form a shoulder in the total molecular weight distribution As long as it is duplicated. The total molecular weight distribution is measured by gel permeation chromatography.

  Furthermore, a method is provided for interrupting the polymerization by adding a suitable functional sulfur compound. In this case, the end of each chain is functionalized by selecting an appropriate sulfur compound. At the same time, the halogen atoms are removed from the polymer at the ends and the transition metal required for the polymerization is almost completely precipitated. This can then be easily separated by filtration.

  In one variation of the present invention, a method of synthesizing a telechelic ABA triblock copolymer having a polydispersity index greater than 1.8 is a continuously performed atom transfer radical polymerization (ATRP), A method is provided wherein a difunctional initiator is added to the polymerization solution and the block copolymer as a whole and the type B block also has a polydispersity index greater than 1.8. By selecting a continuous polymerization method, this method corresponds to the production of a polymer having no block structure. An ABA triblock copolymer or CABAC pentablock copolymer is constructed by the addition of the second monomer mixture A, and optionally subsequent addition of the monomer mixture C at a time offset. The start of the polymerization, the polymerization of the central block B, and the interruption of the polymerization by addition of an appropriate sulfur compound are carried out in the same manner as in the production of a polymer having no block structure. Accordingly, both structures can be considered identical in view of the following description.

Block copolymers are produced by a continuous polymerization process. This means, for example, that the monomer mixture for synthesizing the block of A is only obtained after the polymerization time t ₂ when at least 90%, preferably at least 95% of the monomer mixture for synthesizing the block of B has reacted. It means to add to. This method ensures that the B block contains no monomer of composition A and that the A block contains less than 10%, preferably less than 5% of the total amount of monomer of composition B. According to this definition, block boundaries exist at each point of the chain where the first repeating unit of the monomer mixture to be added (mixture A in this example) is present. The reaction rate of only 95% has the advantage of allowing an efficient transition to the polymerization of the second monomer composition, in particular the methacrylate composition, especially when the residual monomer is an acrylate. Yes. In this way, the yield of block copolymer is clearly improved.

In the process according to the invention, the initiator for polymerizing the monomer mixture B with respect to the monomer mixture or block copolymer is added in two batches to the polymerization solution. Polymerization is initiated by the first batch and, in total, a relatively long polymerization time forms a polymer chain with a relatively high molecular weight. After time may vary depending on the desired molecular weight t _1, with the proviso that at least 30 minutes, preferably after at least 60 minutes, adding a second monomer batch. This second initiation first forms a polymer of composition B having a relatively low molecular weight. The first initiator batch is then 10% to 90%, preferably 25% to 75% of the total initiator amount. Alternatively, it is possible to add the initiator in more than two batches. In this way, a macroinitiator of composition B for the continuous construction of block copolymers of composition ABA is formed. These macroinitiators themselves have a molecular weight distribution with a polydispersity index of 1.8 to 3.0, preferably 1.9 to 2.5. When synthesizing a block copolymer, the addition of the monomer mixture A, after a polymerization time t _2. The polymerization time t ₂ is at least a further 60 minutes, preferably at least 90 minutes. Due to the properties of ATRP, at this point both polymer species of composition B previously initiated are subjected to polymerization, and polymer block A is constructed under the already known assumptions of ATRP. These segments of the polymer chain themselves have a correspondingly narrow molecular weight distribution. In this case, in the case of pentablock polymers, type C or D blocks can also be constructed correspondingly.

  Another advantage of the present invention is further that recombination is prevented. For example, this method can also suppress the formation of a particularly high molecular weight. Such polymer components can contribute to an excessive increase in solution viscosity or melt viscosity. Rather, the widely dispersed unimodal polymer produced by the present invention has a new type of polymer distribution. The charge of a portion of the initiator for the initial initiation provides the longest polymerization time and thus forms the chain with the highest molecular weight in the final product. Thus, in addition to a high molecular weight, a polymer having the properties of a polymer produced by a more controlled polymerization is obtained. However, this distribution is similar to products produced by conventional radical polymerization for low molecular weights or shows a significant spread of molecular weight distributions wider than that. The total molecular weight distribution of the polymer produced according to the present invention has a polydispersity index greater than 1.8.

  According to the present invention, the polydispersity index, which is the quotient of the molecular weight mass average and number average, is described as a measure for the heterogeneity of the molecular weight distribution. Molecular weight is measured against PMMA standard solution by gel permeation chromatography (GPC).

  Another object of the present invention is to appropriately functionalize ABA, CABAC, ACBCA or CDBDC block copolymers having a broad unimodal molecular weight distribution at the chain ends. This problem has been solved by adding a suitable sulfur compound after ATRP has been performed to precipitate the transition metal compound and at the same time functionalize the chain ends of the polymer. In this way the chain ends are functionalized up to at least 75%, preferably up to at least 85%.

  Advantageously, according to the invention, the reaction reagent added to the polymer solution after or while the polymerization is interrupted is a compound containing sulfur in an organically bound form. Particularly advantageously, these sulfur-containing compounds used for precipitating transition metal ions or transition metal complexes have an SH group and at the same time a second functional group. The second functional group is particularly preferably a hydroxy group, an acid group or a silyl group. Particularly advantageous compounds are those which are readily available on the market and are used as regulators in free radical polymerization. The advantages of these compounds are their availability, low cost, and a wide range of changes that allow the precipitation reagent to be optimally adapted to the respective polymerization system. However, the present invention is not limited to these compounds.

  As organic compounds, particularly advantageously functionalized mercaptans and / or other functionalized or unfunctionalized compounds, one or more thiol groups and one or more other functional groups And / or a compound capable of forming a corresponding thiol group and / or one or more other functional groups under dissolution conditions.

The hydroxy-functional sulfur compound may be an organic compound such as mercaptoethanol, mercaptopropanol, mercaptobutanol, mercaptopentanol or mercaptohexanol. The acid functional sulfur compound may be, for example, an organic compound such as thioglycolic acid or mercaptopropionic acid. The silyl-functional sulfur compound may be, for example, a compound that is readily available in a market that is industrially important as a fixing agent. The advantages of these compounds are their availability and low price. One example of such a compound is 3-mercaptopropyltrimethoxysilane, commercially available from Evonik Industries under the name DYNALYSAN® MTMO. Other available silanes are 3-mercaptopropyltriethoxysilane or 3-mercaptopropylmethyldimethoxysilane (ABCR). So-called α-silanes are particularly reactive. In these compounds, the mercapto group and the silane group are bonded to the same carbon atom (that is, R ¹ is usually —CH ₂ —). Such types of corresponding silane groups are particularly reactive and thus lead to a wide range of applications in the subsequent preparation. An example of such a compound is mercaptomethylmethyldiethoxysilane (ABCR). In free radical polymerization, the amount of modifier is often described as 0.05% to 5% by weight, based on the monomer to be polymerized. In the present invention, the amount of sulfur compound used is not relative to the monomer, but relative to the concentration of the polymerization active chain ends in the polymer solution. The polymerization active chain end means the sum of the dormant chain end and the active chain end. The sulfur-containing precipitant according to the invention is used in this sense in an amount of 1.5 molar equivalents, preferably 1.2 molar equivalents, particularly preferably 1.1 molar equivalents, and very particularly preferably 1.05 molar equivalents. Is done. The remaining amount of residual sulfur can be easily removed by changing the subsequent filtration step.

  One skilled in the art will recognize that the described mercaptans cannot further affect the polymer upon addition of the polymer solution, during or after the interruption of the polymerization, with the exception of the described substitution reaction. It is easy to understand. This is especially true with respect to molecular weight distribution, molecular weight, additional functional groups, glass transition temperature or melting temperature in partially crystalline polymers and polymer structures.

  The telechelic polymer or block copolymer according to the invention may have additional functional groups that may correspond to the end groups or may differ from the end groups. In the block copolymer, these additional functional groups can be suitably incorporated into one or more blocks. The following listings are merely examples for illustrating the invention and are not intended to limit the invention in any way. For example, the telechelic polymer may have additional OH groups. Suitable hydroxy-functional (meth) acrylates for this purpose are preferably linear, branched or alicyclic hydroxyalkyl (meth) acrylates of diols having 2 to 36 carbon atoms, for example 3-hydroxypropyl (meth) acrylate, 3,4-dihydroxybutyl mono (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2, 5-Dimethyl-1,6-hexanediol mono (meth) acrylate, particularly preferably 2-hydroxyethyl methacrylate. Examples of the amine group include 2-dimethylaminoethyl-methacrylate (DMAEMA), 2-diethylaminoethyl-methacrylate (DEAEMA), 2-t-butylaminoethyl-methacrylate (t-BAEMA), 2-dimethylaminoethyl-acrylate (DMAEA). , 2-diethylaminoethyl-acrylate (DEAEA), 2-t-butylaminoethyl-acrylate (t-BAEA), 3-dimethylaminopropyl-methacrylamide (DMAPMA) and 3-dimethylaminopropyl-acrylamide (DMAPA) It can be produced by polymerization.

  The polymer having an allyl group can be realized, for example, by copolymerization of allyl (meth) acrylate. The polymer having an epoxy group is obtained by copolymerization of glycidyl (meth) acrylate. The acid group can be realized by copolymerization of t-butyl (meth) acrylate and subsequent saponification or separation of isobutene by heat.

Examples of (meth) acrylate bound silyl _{group, -SiCl 3, -SiMeCl 2, -SiMe} 2 Cl, -Si (OMe) 3, -SiMe (OMe) 2, -SiMe 2 (OMe), - Si (OPh ) ₃ , -SiMe (OPh) ₂ , -SiMe ₂ (OPh), -Si (OEt) ₃ , -SiMe (OEt) ₂ , -SiMe ₂ (OEt), -Si (OPr) ₃ , -SiMe (OPr) ₂ , -SiMe ₂ (OPr), -SiEt (OMe) ₂ , -SiEtMe (OMe), -SiEt ₂ (OMe), -SiPh (OMe) ₂ , -SiPhMe (OMe), -SiPh ₂ (OMe),- SiMe (OC (O) Me) 2, -SiMe 2 (OC (O) Me), - SiMe (O-N = CMe 2) 2 or _{-SiMe 2 (O-N = CMe} 2) and the like. In that case, the abbreviation Me represents a methyl group, Ph represents a phenyl group, Et represents an ethyl group, and Pr represents an iso-propyl group or an n-propyl group. A commercially available monomer is, for example, Dynasylan® MEMO from Evonik Degussa GmbH. This is 3-methacryloxypropyltrimethoxysilane.

  The description method (meth) acrylate represents an ester of (meth) acrylic acid, and here also represents methacrylates such as methyl methacrylate, ethyl methacrylate, etc., acrylates such as methyl acrylate, ethyl acrylate, etc., as well as mixtures of both. Monomers that are polymerized in both block A and block B are (meth) acrylates, for example alkyl (meth) acrylates of linear, branched or alicyclic alcohols having 1 to 40 carbon atoms. For example, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, 2-ethylhexyl (meth) Acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, aryl (meth) acrylate, for example, each unsubstituted or substituted aryl group 1 to 4 times Benzyl which may have Of (meth) acrylate or phenyl (meth) acrylate, other aromatic substituted (meth) acrylates such as naphthyl (meth) acrylate, ethers having 5 to 80 carbon atoms, polyethylene glycol, polypropylene glycol or mixtures thereof Mono (meth) acrylates such as tetrahydrofurfuryl methacrylate, methoxy (m) ethoxyethyl methacrylate, 1-butoxypropyl methacrylate, cyclohexyloxymethyl methacrylate, benzyloxymethyl methacrylate, furfuryl methacrylate, 2-butoxyethyl methacrylate, 2-ethoxyethyl Methacrylate, allyloxymethyl methacrylate, 1-ethoxybutyl methacrylate, 1-ethoxyethyl methacrylate Over DOO, ethoxymethyl methacrylate, poly (ethylene glycol) methyl ether (meth) acrylate and poly (propylene glycol) is selected from the group consisting of methyl ether (meth) acrylate.

  In addition to the (meth) acrylate, the composition to be polymerized may contain the (meth) acrylate and further unsaturated monomers copolymerizable with ATRP. This includes in particular 1-alkenes such as 1-hexene, 1-heptene, branched alkenes such as vinylcyclohexane, 3,3-dimethyl-1-propene, 3-methyl-1-diisobutylene, 4-methyl. -1-pentene, acrylonitrile, vinyl esters such as vinyl acetate, styrene, substituted styrenes having an alkyl substituent on the vinyl group, such as α-methyl styrene and α-ethyl styrene, one or more alkyl substituents on the ring Substituted styrenes such as vinyl toluene and p-methyl styrene, halogenated styrenes such as monochlorostyrene, dichlorostyrene, tribromostyrene and tetrabromostyrene, heterocyclic compounds such as 2-vinylpyridine, 3-vinylpyridine, 2-methyl- 5-vinylpyridine, 3-ethyl-4-vinylpyridine, 2,3-dimethyl-5-vinylpyridine, vinylpyrimidine, 9-vinylcarbazole, 3-vinylcarbazole, 4-vinylcarbazole, 2-methyl-1-vinyl In imidazole, vinyl oxolane, vinyl furan, vinyl thiophene, vinyl thiolane, vinyl thiazole, vinyl oxazole and isoprenyl ether, maleic acid derivatives such as maleic anhydride, maleimide, methylmaleimide and dienes such as divinylbenzene and A block respectively. Hydroxy functionalized and / or amino functionalized and / or mercapto functionalized compounds. Furthermore, these copolymers may be prepared such that the copolymer has a hydroxy functionality and / or an amino functionality and / or a mercapto functionality in one substituent. Such monomers include, for example, vinylpiperidine, 1-vinylimidazole, N-vinylpyrrolidone, 2-vinylpyrrolidone, N-vinylpyrrolidine, 3-vinylpyrrolidine, N-vinylcaprolactam, N-vinylbutyrolactam, vinyl hydride. Thiazole and hydrogenated vinyl oxazole. Particularly advantageously, vinyl esters, vinyl ethers, fumaric acid esters, maleic acid esters, styrene or acrylonitrile are copolymerized with the A block and / or B block.

This process can be carried out in any halogen-free solvent. Preferably toluene, xylene, H ₂ O, acetate, preferably butyl acetate, ethyl acetate, propyl acetate, ketone, preferably ethyl methyl ketone, acetone, ether, aliphatic compounds, preferably pentane, hexane, Biodiesel, or also a plasticizer, such as low molecular weight propylene glycol or phthalate.

  A block copolymer of composition ABA is produced by continuous polymerization.

  Besides solution polymerization, ATRP can also be carried out as emulsion polymerization, miniemulsion polymerization, microemulsion polymerization, suspension polymerization or bulk polymerization. The polymerization can be carried out at standard pressure, reduced pressure or overpressure. The polymerization temperature is not critical. However, the temperature is generally in the range from -20 ° C to 200 ° C, preferably from 0 ° C to 130 ° C and particularly preferably from 50 ° C to 120 ° C.

  The polymers according to the invention preferably have a number average molecular weight of from 5000 g / mol to 100,000 g / mol, particularly preferably from 7500 g / mol to 50000 g / mol and very particularly preferably not more than 30,000 g / mol.

As bifunctional _{initiators, RO 2 C-CHX- (CH} 2) n -CHX-CO 2 R, RO 2 C-C (CH 3) X- (CH 2) n -C (CH 3) X- _{CO 2 R, RO 2 C-} CX 2 - (CH 2) n -CX 2 -CO 2 R, RC (O) -CHX- (CH 2) n -CHX-C (O) R, RC (O) - _{C (CH 3) X- (CH} 2) n -C (CH) 3 X-C (O) R, RC (O) -CX 2 - (CH 2) n -CX 2 -C (O) R, XCH _{2 -CO 2 - (CH 2)} n -OC (O) CH 2 X, CH 3 CHX-CO 2 - (CH 2) n -OC (O) cHXCH 3, (CH 3) 2 CX-CO 2 - ( _{CH 2) n -OC (O)} CX (CH 3) 2, X 2 CH-CO 2 - (CH 2) n -OC (O) CHX 2, CH 3 CX 2 -CO 2 - (CH 2) n - OC (O) CX ₂ CH ₃ , XCH ₂ C (O) C (O) CH ₂ X, CH ₃ CHXC (O) C (O) C (O) CHXCH ₃ , XC (CH ₃ ) ₂ C (O) C (O) CX (CH ₃ ) _{2 , X 2 CHC (O) C} (O) CHX 2, CH 3 CX 2 C (O) C (O) CX 2 CH 3, XCH 2 -C (O) -CH 2 X, CH 3 -CHX-C ( _{O) -CHX-CH 3, CX} (CH 3) 2 -C (O) -CX (CH 3) 2, X 2 CH-C (O) -CHX 2, C 6 H 5 -CHX- (CH 2) _{n -CHX-C 6 H 5,} C 6 H 5 -CX 2 - (CH 2) n -CX 2 -C 6 H 5, C 6 H 5 -CX 2 - (CH 2) n -CX 2 -C 6 H _5, o-, m- or _{p-XCH 2 -Ph-CH 2} X, o-, m- or _{p-CH 3 CHX-Ph-} cHXCH 3, o-, m- or p- (CH _{3) 2 CX-Ph-CX (CH 3} ) 2 , O-, m- or _{p-CH 3 CX 2 -Ph-} CX 2 CH 3, o-, m- or _{p-X 2 CH-Ph-} CHX 2, o-, m- or p-XCH ₂ -CO _{2 -Ph-OC (O) CH} 2 X, o-, m- or _{p-CH 3 CHX-CO 2} -Ph-OC (O) cHXCH 3, o-, m- or p- (CH _{3) 2} CX _{-CO 2 -Ph-OC (O)} CX (CH 3) 2, CH 3 CX 2 -CO 2 -Ph-OC (O) CX 2 CH 3, o-, m- or p-X ₂ CH-CO ₂ -Ph-OC (O) CHX ₂ or o-, in m- or _{p-XSO 2 -Ph-SO 2} X ( wherein, X represents chlorine, bromine or iodine, Ph is a phenylene (C ₆ H ₄₎ R represents an aliphatic group having 1 to 20 carbon atoms, the group having a linear, branched or cyclic structure May be saturated, monounsaturated, polyunsaturated, and may have one or more aromatics, or may not have aromatics, and n is 0 Can be used). 1,4-butanediol-di- (2-bromo-2-methylpropionate), 1,2-ethylene glycol di- (2-bromo-2-methylpropionate), 2,5 Use dibromo-adipic acid-di-ethyl ester or 2,3-dibromo-maleic acid-di-ethyl ester. The ratio of initiator to monomer results in a later molecular weight when all monomers have reacted.

Catalysts for ATRP are described in Chem. Rev. 2001, 101, 2921. Although mainly copper complexes are described, in particular compounds of iron, rhodium, platinum, ruthenium or nickel are used. In general, any transition metal compound capable of forming a redox cycle with an initiator or a polymer chain having a transferable atom can be used. For this purpose, for example, copper starts from Cu ₂ O, CuBr, CuCl, CuI, CuN ₃ , CuSCN, CuCN, CuNO ₂ , CuNO ₃ , CuBF ₄ , Cu (CH ₃ COO) or Cu (CF ₃ COO). Can be added to the system.

One alternative to the described ATRP is a variation thereof. In so-called reverse ATRP, compounds with higher oxidation numbers, such as CuBr ₂ , CuCl ₂ , CuO, CrCl ₃ , Fe ₂ O ₃ or FeBr ₃ , can be used. In these cases, the reaction can be initiated by classical radical formers such as AIBN. In this case, the transition metal compound is first reduced. This is because transition metal compounds react with radicals generated from classical radical formers. This reverse ATRP is described in Macromolecules (1995), 28, 7572, especially by Wang and Matyjaszewski.

  One variation of reverse ATRP is to additionally use a zero oxidation number metal. The predicted equalization reaction with higher oxidation number transition metals promotes the rate of reaction. This method is described in detail in WO 98/40415.

  The molar ratio of transition metal to difunctional initiator is generally in the range from 0.02: 1 to 1-20: 1, preferably in the range from 0.02: 1 to 6: 1 and particularly preferably from 0. Although the range is 2: 1 to 4: 1, the molar ratio should not be limited thereby.

  In order to increase the solubility of the metal in the organic solvent and at the same time avoid the formation of a stable and thereby polymerization-inactive organometallic compound, a ligand is added to the system. The ligand additionally relaxes the abstraction reaction of the transferable atomic group by the transition metal compound. A list of known ligands is described, for example, in WO 97/18247, WO 97/47661 or WO 98/40415. The coordination component often has one or more nitrogen, oxygen, phosphorus and / or sulfur atoms of the compounds used as ligands. Particularly advantageous in this case are nitrogen-containing compounds. Particularly advantageous are nitrogen-containing chelating ligands. Examples include 2,2'-bipyridine, N, N, N ', N ", N" -pentamethyldiethylenetriamine (PMDETA), tris (2-aminoethyl) amine (TREN), N, N, N', N ' -Tetramethylethylenediamine or 1,1,4,7,10,10-hexamethyltriethylenetetramine. Valuable suggestions for the selection and combination of the individual components can be found by the person skilled in the art in WO 98/40415.

  These ligands can form a coordination compound in situ with the metal compound or they can be first prepared as a coordination compound and subsequently added to the reaction mixture. The ratio of ligand (L) to transition metal depends on the number of ligand coordination sites and the coordination number of transition metal (M). This molar ratio is generally in the range from 100: 1 to 0.1: 1, preferably in the range from 6: 1 to 0.1: 1 and particularly preferably in the range from 3: 1 to 1: 1. Should not be limited by. After ATRP is complete, the transition metal compound is precipitated by the addition of the sulfur compound. For example, by addition of mercaptan, the halogen atom at the chain end is replaced with the generation of hydrogen halide. A hydrogen halide, such as HBr, is protonated at the ligand L coordinated to the transition metal to an ammonium halide. This process quenches the transition metal-ligand complex and precipitates the “bare” metal. Subsequently, the polymer solution can be easily purified by simple filtration. Said sulfur compound is preferably a compound having an SH group. The sulfur compounds are particularly preferably regulators known from radical polymerization.

  A broad field of application arises for these products. The choice of application is not suitable for limiting the use of the polymers according to the invention. Advantageously, telechelic polymers with reactive groups can be used as prepolymers for moisture curable crosslinking. The prepolymer can be crosslinked by any polymer. Advantageous applications of telechelic polymers, for example with silyl groups, according to the invention are in sealants, reactive melt adhesives or adhesive materials. Used in particular in the field of construction of vehicles, ships, containers, machinery and aircraft, as well as in the electronics industry and in sealants in the manufacture of household equipment. Other advantageous fields of application are sealants for the field of architecture, the field of heat sealing or assembly adhesives.

  However, possible applications of the material produced according to the invention are not only as a binder for sealants, or as an intermediate step for introducing other types of functional groups. EP 1510550 describes, for example, a coating composition consisting in particular of acrylate particles and polyurethane. The polymers according to the invention lead to improved processing and crosslinking properties in the corresponding preparations. Possible applications are, for example, powder coating preparations.

  With the novel binder it is possible to produce, for example, crosslinkable one-component and two-component elastomers for the applications described above. Other conventional components of the preparation are solvents, fillers, pigments, plasticizers, stabilizing additives, water scavengers, fixing agents, thixotropic agents, crosslinking catalysts, thickeners (tackifiers), etc. .

  To lower the viscosity, solvents such as aromatic hydrocarbons such as toluene and xylene, esters such as ethyl acetate, butyl acetate, amyl acetate and cellulose acetate, ketones such as methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone and the like Can be used. The solvent can already be added during the radical polymerization process.

  For example, crosslinking catalysts for hydrosilylated binders in preparations containing the corresponding polyurethanes are conventional organotin, lead, mercury and bismuth catalysts such as dibutyltin dilaurate (eg BNT Chemicals GmbH), dibutyltin disulfide. Acetate, dibutyltin diketonate (eg, Metan740 from Acima / Rohm + Haas), dibutyltin dimaleate, tin naphthenate, and the like. Reaction products of organotin compounds, such as the reaction product of dibutyltin dilaurate and silicate esters (eg DYNASIL A and 40), can also be used as crosslinking catalysts. In addition, titanate (eg, tetrabutyl titanate, tetrapropyl titanate), zirconate (eg, tetrabutyl zirconate), amine (eg, butylamine, diethanolamine, octylamine, morpholine, 1,3-diazabicyclo [5. 4.6] undecene-7 (DBU) etc.) or their carboxylates, low molecular weight polyamides, aminoorganosilanes, sulfonic acid derivatives and mixtures thereof.

  The advantages of block copolymers are that they are colorless and have no odor in the manufactured product. Another advantage of the present invention is that the number of functional groups is limited. A high proportion of functional groups in the binder leads to premature gelling in some cases, or at least an additional increase in solution or melt viscosity.

  The examples described below are intended to illustrate the invention in more detail, but are not intended to limit the invention to the features disclosed herein.

Examples Number average molecular weight Mn or mass average molecular weight Mw, and polydispersity index D = Mw / Mn as a measure of molecular weight distribution are measured by gel permeation chromatography (GPC) against PMMA standard solution in tetrahydrofuran. .

  The following examples are limited to the synthesis of ABA triblock copolymers. It should be readily apparent to those skilled in the art that these results can be readily transferred to polymers or pentablock copolymers that do not have a block structure.

Comparative Example 1
N-Butyl acetate under a N ₂ atmosphere in a double-walled vessel equipped with a stirrer, thermometer, reflux condenser, nitrogen inlet tube and dropping funnel (see Table 1 for exact amounts), 180 mL ethyl acetate, copper (I) oxide (see table 1 for amounts) and N, N, N ', N ", N" -pentamethyldiethylenetriamine (PMDETA, see table 1 for amounts) Was loaded. The solution was stirred at 70 ° C. for 15 minutes. Subsequently, at the same temperature, a certain amount of initiator 1 (see Table 1) 1,4-butanediol-di- (2-bromo-2-methylpropionate) (BDBIB, the total amount of initiator was acetic acid Dissolved in 26 mL of ethyl) was added. After a polymerization time of 3 hours, a sample is taken to determine the average molecular weight Mn (by SEC) and a mixture of 100 mL ethyl acetate and methyl methacrylate (see Table 2 for exact amounts) Added. The mixture was polymerized until the expected reaction rate of at least 95% was achieved and interrupted by the addition of 2.0 g mercaptoethanol and further stirred at 75 ° C. for 50 minutes. The solution was worked up by filtration through silica gel and subsequent removal of volatile components by distillation. The average molecular weight was finally measured by SEC measurement.

Comparative Example 2
The polymerization was carried out in the same manner as in Comparative Example 1 with the addition of the amounts listed in Table 1. The reaction was interrupted by adding 2.0 g of thioglycolic acid.

Comparative Example 3
The polymerization was carried out in the same manner as in Comparative Example 1 with the addition of the amounts listed in Table 1. The reaction was interrupted with the addition of 5.0 g of Dynasylan MTMO.

  Comparative Examples 1-3 show that the conventional initiator addition in one batch results in a polymer with a relatively narrowly distributed internal block and a polydispersity index less than 1.4. .

  After removal of the solvent, the silyl functionalized product can be stabilized by the addition of a suitable desiccant. In this way, good storage stability is ensured without further increase in molecular weight.

Example 1
N-Butyl acrylate under N ₂ atmosphere in a double-walled vessel equipped with stirrer, thermometer, reflux condenser, nitrogen inlet tube and dropping funnel (see Table 1 for exact amounts) 180 ml of ethyl acetate, copper (I) oxide (see table 1 for amounts) and N, N, N ′, N ″, N ″ -pentamethyldiethylenetriamine (PMDETA, see table 1 for amounts) ). The solution was stirred at 70 ° C. for 15 minutes. Subsequently, at the same temperature, a certain amount of initiator 1 (see Table 1) 1,4-butanediol-di- (2-bromo-2-methylpropionate) (BDBIB, the total amount of initiator was acetic acid Was dissolved in 26 mL of propyl). After a reaction time of 2 hours, a certain amount of initiator 2 (see Table 1) 1,4-butanediol-di- (2-bromo-methylpropionate) (BDBIB) was added to the reaction solution. . After all of the initiator has been added, the polymerization solution is stirred for a further 2 hours at the polymerization temperature, then a sample is taken to determine the average molecular weight Mn (by SEC) and methyl methacrylate (the exact amount listed is (See Table 1). The mixture was further stirred at 75 ° C. for 2 hours and subsequently interrupted by addition of 2.1 g mercaptoethanol. The solution was worked up by filtration through silica gel and subsequent removal of volatile components by distillation. The average molecular weight was finally measured by SEC measurement.

Example 2
Polymerization was carried out in the same manner as in Example 1 by adding the amounts listed in Table 2. The reaction was interrupted by adding 2.3 g of thioglycolic acid.

Example 3
Polymerization was carried out in the same manner as in Example 1 while adding the amounts shown in Table 2 and maintaining the times shown in the table. The interruption of the reaction was carried out by adding 4.9 g of Dynasylan MTMO.

  The molecular weight distribution of the first polymerization stage is bimodal in each case and has a polydispersity index D greater than 1.8. The final product has a correspondingly large, but smaller polydispersity index compared to the pure B block. This effect is generally a result of the higher molecular weight, but also indicates that the polymerization of the A block proceeds in a controlled manner and that the block itself has a narrow molecular weight distribution.

The diversion of this result to a pentablock copolymer of the composition ACBCA or CABAC can be done similarly. The synthesis of copolymers with such a narrow distribution is described, for example, in the unpublished patent application DE 102008002016 by the same applicant. This method can be transferred to a polymer having no block structure without any problem. In this case, the mercaptan is added directly after the polymerization time t _{2 in place} of the monomer mixture A.

  For ATRP, a bimodal distribution for the system is described. However, the bimodality of these polymers is in each case caused on the one hand by the presence of block copolymers and on the other hand by the presence of unreacted macroinitiators. The disadvantage of this method is that it produces a product consisting of a mixture of two different polymer compositions. EP 1637550 describes the synthesis of MMA-nBA-MMA-triblock copolymers for use in thermoplastic elastomers. The person skilled in the art knows that such materials have a very narrow molecular weight distribution in all blocks at most. Paris et al. (European Polymer Journal, 44, 5, 1403-13, 2008) introduce a triblock copolymer having an A block consisting of allyl methacrylate. Here, the B block has a unimodal narrow molecular weight distribution, while the A block is bimodal, broad and branched. In WO 99/20659, polymers having a total distribution of less than 2.5 on the one hand and triblock copolymers on the other hand are pointed out, but the teachings on the synthesis of widely distributed triblock copolymers or such polymers themselves Is not listed.

Claims (22)

  In a process for producing a polymer by continuous atom transfer radical polymerization (ATRP), a bifunctional initiator is added to the polymerization solution in two batches, and the end of the polymer chain is attached to a second functional group. A process for producing a polymer, characterized in that it is functionalized by the addition of a suitable sulfur compound having a group and the block copolymer of composition ABA has a molecular weight distribution with a polydispersity index generally greater than 1.8.   The two batches of initiator are added separately in time from each other and the first initiator batch is 10% to 90%, preferably 25% to 75% of the total initiator amount The method for producing a polymer according to claim 1, wherein:   3. A process according to claim 2, characterized in that the second initiator batch is added at least 30 minutes, preferably at least 60 minutes after the first initiator batch.   The method for producing a polymer according to claim 1 or 2, wherein the sulfur compound has an acid group, a hydroxy group, a silyl group, an allyl group or an amine group as the second functional group.   The method for producing a polymer according to claim 4, wherein the addition of the sulfur compound simultaneously removes the halogen atom at the end of the polymer chain and precipitates the ATRP catalyst.   Process for producing a polymer according to claim 4, characterized in that the chain ends are functionalized to at least 75%, preferably at least 85%, by addition of sulfur compounds.   The method for producing a polymer according to claim 1, wherein the polymer is polyacrylate, polymethacrylate, or a copolymer composed of acrylate and methacrylate.   8. The method for producing a polymer according to claim 7, wherein the polymer or the one or more polymer blocks further contain an acrylate and / or methacrylate having an additional functional group.   The polymer, or one or more polymer blocks, further contains vinyl ester, vinyl ether, fumarate ester, maleate ester, styrene, acrylonitrile, or other monomer polymerizable by ATRP, Item 8. A method for producing a polymer according to Item 7.   2. A process for producing a polymer according to claim 1, characterized in that the polymer has a number average molecular weight of 5000 g / mol to 100,000 g / mol, preferably 7500 g / mol to 50000 g / mol.   11. A process for producing a polymer according to any one of claims 1 to 10, characterized in that the polymer is a block copolymer, preferably a block copolymer of the composition ABA, ACBCA or CABAC.   Block A is a copolymer having a monomodal molecular weight distribution with a polydispersity index less than 1.6, and Block B has a bimodal molecular weight distribution with a polydispersity index greater than 1.8 12. A process for the production of a block copolymer of composition ABA according to claim 11, characterized in that it is a copolymer, in which the monomer may be (meth) acrylate or a mixture of (meth) acrylates.   Blocks A and C are copolymer blocks having a unimodal molecular weight distribution, each having a polydispersity index of less than 1.6, wherein the monomer comprises (meth) acrylate or a mixture of (meth) acrylates The method for producing a block copolymer of composition ACBCA or CABAC according to claim 11, characterized in that no monomer having another functional group is used in block C.   The initiator is added in two batches separated in time from each other, and the first initiator batch is 10% to 90%, preferably 25% to 75% of the total initiator amount. 14. A process for producing a polymer according to claim 12 or 13, characterized in that   15. A process according to claim 14, characterized in that the second initiator batch is added at least 30 minutes, preferably at least 60 minutes after the first initiator batch.   15. The block copolymer according to claim 14, characterized in that the addition of the second initiator batch is added to the polymerization solution at least 60 minutes, preferably at least 90 minutes before the addition of the monomer mixture A or C. Production method.   In the polymer, at least 75%, preferably at least 85% of the chain ends have functional groups that do not have halogen atoms, and the molecular weight distribution is bimodal and polydisperse 11. A sex index greater than 1.8, characterized in that the monomer is obtained by the method according to any one of claims 1 to 10, wherein the monomer is selected from (meth) acrylate or a mixture of (meth) acrylates. A polymer.   In the ABA triblock copolymer, at least 75%, preferably at least 85% of the chain ends have functional groups that do not have halogen atoms, and the polydispersity index is from 1.8 A large ABA triblock copolymer having a monomodal molecular weight distribution with a polydispersity index less than 1.6 and a bimodal molecular weight distribution with a polydispersity index greater than 1.8 An ABA triblock, characterized in that it is obtained by the process according to claim 12, wherein the monomer is selected from (meth) acrylates or mixtures of (meth) acrylates Copolymer.   In a pentablock copolymer of composition ACBCA or BACAB, the chain ends have at least 75%, preferably at least 85%, functional groups that do not have halogen atoms, and the polydispersity index is Blocks A and C, which are pentablock copolymers greater than 1.8 and having a unimodal molecular weight distribution with a polydispersity index less than 1.6, and a polydispersity index greater than 1.8 14. A composition obtainable by the process according to claim 13, comprising a block B having a bimodal molecular weight distribution and wherein the monomer is selected from (meth) acrylate or a mixture of (meth) acrylates. ACBCA or BACAB pentablock copolymer.   20. Use of a polymer according to any one of claims 16 to 19 for producing a melt adhesive, a flowable adhesive, a pressure sensitive adhesive, an elastic sealant, a coating or a foamed material precursor.   20. Use of a polymer according to any one of claims 16 to 19 for producing a heat sealing material.   20. Use of a polymer according to any one of claims 16 to 19 in a crosslinkable composition wherein the block copolymer has reactive functional groups.