Process for producing functionalised polymers

The invention relates to a process for the preparation of functionalized polymers by means of radical solid-phase graft polymerization of α, β-ethylenically unsaturated compounds having functional groups onto olefinic and / or diene thermoplastics and elastomers.

It is known to use both olefinic homopolymers and copolymers and also dienic homopolymers and statistical or alternating copolymers, and especially block copolymers, in many cases also in selectively hydrogenated form, for which a broad range of applications, ie from the usual thermoplastics to technically important ones Rubbers and thermoplastic elastomers (TPE) is available for various important areas of application by subsequent polymerisation of specific functional group-containing monomers (so-called functional monomers) to be chemically modified in the parent or backbone polymer chain.

In addition to the homopolyolefins (PO), such as polyethylenes (PE) and polypropylenes (PP), the backbone polymers used are, above all, olefinic and / or diene copolymers and block copolymers, in particular ethylene / propylene copolymers (EPM), ethylene / propylene / diene (dicyclopentadiene and / or norbornene) terpolymers (EPDM), ethylene / vinyl acetate copolymers (EVA, EVM), ethylene / (meth) acrylate copolymers (EAM), styrene / ethylene-butylene / styrene (SEBS) and styrene / ethylene-propylene / Styrene three-block copolymers (SEPS), including their mixtures with one another, such as EPM or EPDM / PO (PE and / or PP) and SEBS or SEPS / PO and / or EPM or EVA, and last but not least also the classic rubbers based on conjugated dienes, such as 1.4 cis-polybutadiene (BR), polyisoprene (IR) or natural rubber (NR), statistical styrene / butadiene copolymers (SBR), acrylonitrile / butadiene copolymers (NBR) and styrene / butadiene or isoprene two-block copolymers (SB, SI) or the corresponding three or Four-block copolymers (SBS, SIS or SBSB and the like) or radial styrene / butadiene block copolymers ((SB)_n X with n = 3-12, X = coupling agent). In addition to the use of the functionalized base polymers as an adhesion-resistant film and coating material (US 4,394,485), they are particularly suitable as a well-adhering or compatible component in composite films, laminates and preferably in different thermoplastic molding compositions.

The technical thermoplastics used particularly in the automotive, household appliance and electrical or (micro) electronics sector generally require an adhesion promoter or compatibility agent, in particular with respect to other polymer components, but also non-polymer materials, which usually also results in a significant (notch) impact resistance improvement .

Of the thermoplastics generally used for the above-mentioned fields of application, which are often chemically easily modifiable due to their terminal reactive groups, the polyamides and saturated polyesters in particular have thermoplastic polyurethanes, polyphenyl ethers, polyphenylene sulfides, among others, including their combinations with one another and blends with the inclusion of others Thermoplastics, especially PO, polystyrene (PS) or styrene copolymers, the greatest importance. (DE 2622973 and US 4,174,358, US 4,172,859; EP 0279 578, EP 0234 819, EP 0180 302; US 4,628,072, US 4,657,970, US 4,657,971; EP 0415 344; US 3,668,274, US 3,972,961, US 4,017,557; Ide and Hasegawa, J. Appl. Polym. Sci. 18 (1974), 963, US 4,427,828, US 4,508,874, US 3,972,961, US 4,017,557, US 4,863,996; WO 87/00540, WO 86 / 04076; US 4,594,386; WO 88/07065).

The olefinic and also (unsaturated) dienic polymers can be modified by various graft polymerization processes. Because of their inefficiency and the overall low degree of modification that can be achieved, solution and dispersion grafting technologies which are based on the use of liquid organic and / or aqueous carrier phases (EP 0074811, EP 0187659, DE 2023154, DE 2329780, DE 2420942) have for the functionalization of olefinic backbones little or no commercial importance. Even unhydrogenated and selectively hydrogenated styrene / conjugated diene block copolymers can be functionalized in an organic solvent (analog to maleinization of polyisoprene (JP 20294/74)) by grafting mono- and dicarboxylic acids and their derivatives, in particular maleic anhydride (MSA) (US 4,308,353, EP 0173,380). But here too, working with large quantities of solvents, including their recovery / reprocessing and taking physiological and fire protection aspects into account, has proven to be an obstacle to commercial use.

The majority of the functionalized olefinic thermoplastics / elastomers used are produced on an industrial scale by means of free-radical melt grafting, generally in an extruder or kneader at temperatures between 150 and 300 ° C (EP 0128775, EP 0235876, EP 0266221, EP 0287140, EP 0299499 , EP 0371001, DE 1694126, DE 2242324, DE 2326589, DE 2401149, US 3873643, US 3987122, US 4578429, US 4927889).

Unsaturated styrene / butadiene / styrene three-block copolymers (SBS) are also functionalized by grafting on unsaturated mono- or dicarboxylic acids or their derivatives, in particular MSA, under melt mixing conditions in the absence of a radical initiator, using radical inhibitors to suppress unwanted crosslinking or gel formation (US 4,292,414). In order to carry out such an addition functionalization, also referred to as "ENE" reaction, a minimum proportion of unsaturated bonds in the diene soft segments is necessary. Since the selectively hydrogenated styrene / diene / block copolymers also have a mostly low (between 0.2 and 20%) but sufficient degree of residual unsaturation in their olefin blocks, they can be functionalized by means of the "ENE" reaction (US 4,427,828, US 4,508,874 , EP 0155995). When using MSA as the functional monomer, the MSA addition leads to succinic anhydride groups preferably attached in the allyl position, which are extremely unstable thermally and are relatively easily split off again ("contra-ENE" reaction). The melt-modified SBS or SIS three-block copolymers, including their products crosslinked by mono-, di- or trivalent metal ions, can be used for the processing and application technology of polystyrene (PS) (US 4,308,353), PS / PO mixtures (DE 4217470, DE 3643008, US 4,518 681, EP 0289926, EP 0310051) as well as for the modification of technical thermoplastics and high-performance plastics, such as especially polyamides (PA), thermoplastic polyesters such as polyethylene and polybutylene terephthalate (PET and PBT), polycarbonate (PC) and polyester carbonate (PEC), polyphenylene ether (PPE), polyphenylene sulfide (PPS), thermoplastic polyurethane (TPU), polyoxymethylene (POM), polymethacrylate (PMMA), saponified Ethylene-vinyl acetate copolymers / ethylene-vinyl alcohol copolymers with different degrees of saponification (EVAL) and others, including their blends with styrene polymers and PO, can be used (GB 2053238). Thermally stable and essentially uncrosslinked (gel-free) graft products with improved processing and application properties overall are obtained by grafting carboxyl group-containing monomers and their derivatives, in particular MSA, onto block copolymers with a low degree of ethylenic unsaturation in the polymerized diene block, in particular SEBS and SEPS with a mostly high 1,2-configuration corresponding to high vinyl group contents of the diene middle blocks in the unhydrogenated starting product (SBS and SIS), generally obtained under melt grafting conditions using a radical peroxidic initiator in the extruder (EP 0173380, EP 0262691, EP 0371001, EP 0282664, US 4,578,429, US 4,628,072, US 4,657,970, US 4,657,971). In this case, the grafting of the MSA or the other functional monomers - in contrast to the "ENE" addition - takes place predominantly on the tertiary and secondary carbon atoms of the olefin (EB or EP) segments (US 4,578,429).

Functionalization in the form of maleinization or carboxylation in the melt, despite its many technical uses, is associated with a number of general problems. This is mainly due to the high temperatures, generally between 200 and 300 ° C in the extruder or kneader under high shear forces, and the associated undesirable reactions, in particular polymer crosslinking and degradation reactions and side reactions (homopolymer formation) and / or low or only partial polymerization (escape of volatile monomers) of the functional monomers.

Since the grafting of the melt under the above-mentioned conditions must take place overall in short reaction times, generally between about 3 and a maximum of 20 minutes, the possible melt-grafting systems are limited to those reactants and components which - while simultaneously ensuring their chemical stability, the greatest possible prevention of their escape from the reaction zone and the avoidance of their corrosive effect on the tool material - distribute themselves well in the reaction medium and not suddenly (risk of high homopolymer formation or low grafting yield and a very low degree of grafting) but almost completely in the short reaction time available must be implemented.

It can be concluded from the above that higher monomer and initiator concentrations are prohibited from the outset in order to achieve higher degrees of functionalization. Therefore, practically only a few functional monomers, apart from the MSA that is preferably used, mostly only higher unsaturated (di) carboxylic acids or their anhydrides, are well suited for grafting onto the various backbone polymers. The possibility of variation with regard to the adjustability of the concentration of carboxyl or acid anhydride groups or also of other functional groups and thus the adhesive (adherence or compatibility) effect is thus severely limited.

If the grafting reaction is carried out below the polymer backbone melting temperature, generally between 40 and 130 ° C. with the exclusion of liquid aqueous and / or organic suspension (emulsion) or solvent phases, including the monomer (s) themselves as an independently liquid phase, can be composed especially of predominantly styrene and a functional monomer, such as acrylic acid, monomer mixtures in specially designed PO or Olefin copolymer / monomer gel mixed phases (DD 135 622) or - in the presence of the monomers in the gaseous state (IT 867340, US 3,162 697) - in the form of a gas phase graft (JP 03285936, JP 03285937, JP 03285938), the latter in particular for the preparation of compatibility agents for PA / PO, PC / PO and PBT / PO blends can be copolymerized.

In contrast to the graft functionalization of the thermoplastics and elastomers used as backbone polymers in the polymer melt or in liquid aqueous and / or organic media, this graft polymerization process can be termed solid-phase grafting due to the "solid" consistency of the reaction mixture up to the final conversion of the monomers.

A number of the disadvantages that are fundamental for melt functionalization are avoided and / or avoided by using the extremely economically viable radical solid phase grafting technology. weakened, the various possible backbone polymers - practically from the thermoplastics (PO, such as PE and PP or EVA) via the thermoplastic elastomers (TPE), especially those based on hard PS segment / soft (elastic) diene or olefin oligomer segment / hard PS segment (TPE-S) or from cross-linked EP (D) M / PO compounds (TPE-O) to elastomers (EPM, EPDM, EVM; BR, IR, SBR, NBR; SB, SI ) - and the different graft monomers or Graft monomer mixtures, including compositions of functional and non-functional additional comonomers, can be used, taking into account the specific conditions for the individual grafting systems (DD 136971, DD 275159, DD 275160, DD 275161, DD 266358, DD 290431, DD 290432, DD 300977, DE 4123972, DE 4217469, DE-A P 4342605.0, EP 0469693, EP 0263887, EP 0265527).

A problem of the functionalized thermoplastics / elastomers obtained by means of solid-phase grafting technology, which is not or only insufficiently solved for a whole series of interesting graft systems, is their generally very high degrees of crosslinking, which may even be advantageous for different areas of application, but are very disadvantageous for other uses. This applies above all to the more demanding and at the same time much more expensive rubbers and TPEs, in particular those with higher molecular weights (Mw ≥ 100,000), and the use of monomers containing carboxyl groups in higher concentrations (> 2% by mass) while at the same time ensuring high monomer conversions and grafting yields , both essential prerequisites for highly effective impact modifiers, especially in the low temperature range (0 ° C to approx. -50 ° C), taking into account an overall high level of mechanical and thermal properties and good processability of the thermoplastic molding compositions modified with the functionalized polymers.

The invention is therefore based on the object of developing a process for the production of functionalized polymers using olefinic and / or diene backbone polymers and various α, β-ethylenically unsaturated compounds with functional groups (functional monomers) based on an economic graft technology with simultaneous elimination of the disadvantages which occur under graft polymerization conditions in the liquid aqueous and / or organic phase or in the melt, in particular with regard to the narrowly limited choice of functionality of the olefinic and / or diene graft substrates and the thus restricted graft product characteristic level, with a higher adhesive strength compared to the graft products obtained by known solid-phase graft polymerisation or modifying effect when used as an adhesion promoter / impact modifier in a large number to develop.

According to the invention, the functionalized polymers are prepared by solid-phase graft polymerization using olefinic homo- and / or (block) copolymers and / or conjugated dienic homo- as well as statistical or alternating copolymers and / or block copolymers, including the corresponding selectively hydrogenated polymers, with weight average molecular weights Mw of 10,000 to 1,000,000 as backbone polymers and from 0.05 to 50 parts by weight, based on 100 parts by weight of backbone polymer, of at least one grafted-on molecular unit containing at least one radio -ional group, selected from mono- and dicarboxyl groups, including groups derived therefrom, such as amide or Imide, half-ester and especially anhydride groups, hydroxyl and epoxy groups, amino groups and silane groups, and optionally at least one further co-grafted molecular unit without the functional groups mentioned, such as styrene or Substituted styrene and / or (meth) acrylate units, in a mass ratio of monomer (s) with functional groups (functional monomer (s)) to monomer (e) without named functional groups (additional comonomer (s)) 1 to 100% to 0 to 99%, the total proportion of grafted-on functional plus additional comonomers based on the backbone polymer composition being 0.05 to 50%, the backbone polymer composition being a portion of a mineral, pre-functionalized grafting reaction in particular paraffinic and / or naphthenic and / or aromatic oil and / or a native, in particular vegetable oil in an amount of 10 parts by weight up to a maximum concentration corresponding to the absorption capacity of the polymers used as backbone polymers while maintaining their dry, flowable consistency over the entire graft polymerization process in the limits of 20 to 400 parts by mass, in particular up to 200 parts by mass, each based on 100 parts by weight of backbone polymer.

The addition of an oil quantity which can be selected within wide limits, taking into account the absorption capacity of the individual backbone polymer and which is in particular a cost-reducing action, leads to functionalized graft products with a surprisingly broadly variable modification effect when they are incorporated into different thermoplastic molding compositions, including polymer blends and composites. With a suitable choice of the grafting system, especially using special thermoplastic elastomers with higher molecular weights (<maths id="math0001" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0805827B1_D0001.tif" /></maths>w ≥ 200,000) as backbone polymers which are generally difficult to functionalize without the addition of oil, in particular only with a low grafting yield , as well as acrylic and / or methacrylic acid or Their homologues and / or MSA and other functional monomers, which are grafted onto the backbone up to graft levels of ≥ 2% by mass, result in functionalized, preferably carboxylated, polymers which give a large number of thermoplastic molding compositions a high, often abruptly increasing low-temperature toughness while ensuring all other important ones Give application and processing properties at the required level for demanding applications. This surprisingly reveals the solution according to the invention, which is directly attributable to the specific technological possibilities of solid-phase graft modification using a very wide range of backbone polymers, functional monomers and, if appropriate, additional comonomers. In addition to the general usability of native oils, especially vegetable oils (glycerides of predominantly unsaturated fatty acids), such as beet or Rapeseed oils, soybean oils, etc., and also animal oils (glycerides of predominantly saturated fatty acids) (ULLMANN Vol. 11, pp. 455-524 "Fette und Öle"; Verlag Chemie Weinheim 1976), are especially the well-known saturated mineral oils that are used for paraffinic, for the relatively naphthenic or naphthenic, for the relatively aromatic or Aromatic process oil type belong and are often used in rubber products as mineral oil plasticizers, suitable for the functionalized polymers according to the invention. Other oily hydrocarbon products, such as liquid polybutenes, can also be used in the products according to the invention. Mineral oils of the paraffinic or relatively naphthenic or naphthenic process oil type which have a carbon distribution C_Aromat. to C_Naphthen. to C_Paraffin. from 0 to 10 to 20 to 45 to 45 to 80 and to which viscosity density constants (VDK) between 0.80 and 0.90 can be assigned (E. Balint, rubber, fibers, plastics (<u>GAK</u>) (1993) 6, pp. 286-290). Possible oil additions to the melt or solution graft polymerization approach are known (EP 0173380, EP 0266221), but are only of minor importance or do not represent a mandatory measure that significantly influences the grafting process and especially the properties of the functionalized graft products expect, because due to the specific melt and solution grafting conditions such an addition is not or only effective to a small extent, since the oil, especially when using higher proportions, is largely outside the reaction phase, which also leads to sensitive technical and technological disruptions within the overall process. In addition, in the production of selectively hydrogenated styrene / diene block copolymers maleinized in the melt, the effectiveness of oil as a flow improver which can be added to the graft polymerization batch is not demonstrated anywhere (EP 0173380).

And the possible addition of mineral oil to the melt graft batch in the production of exclusively peroxidically highly crosslinked (high gel content) graft-functionalized olefin elastomers, which act as polyamide impact modifiers (EP 0266221), is a limited measure that is only related to the melt grafting and has no connection whatsoever with the present inventive task .

In general, the more expensive thermoplastic elastomers, such as the TPE-S based on unsaturated and selectively hydrogenated (saturated) styrene / diene block copolymers, if appropriate also in a functionalized form, are not used directly, but instead taking into account optimal usage properties and significantly cheaper use "blended" different additives, a wide range of TPE-S can be set in hardness settings from &lt;30 Shore A to&gt; 65 Shore D, or thermoplastic molding compounds are added as an elasticizing component or impact modifier.

Also known in this context is the oil stretching customary for elastomers, ie the addition of a mineral process oil - not as part of the polymerization batch, but directly during the production of the rubber mixture that can be processed - in amounts of 50 to 300 parts by weight per 100 parts by weight of elastomer, for example TPE-S in the form of a mixture of SEBS and maleinized SEBS, which may optionally contain a PO (US H 1022) as a further component or generally further elastomers and resins (EP 0085115, EP 0216347).

The functionalized polymers according to the invention, in particular the carboxylated thermoplastic elastomers of the type TPE-S and also TPE-O, are distinguished from known functionalized thermoplastics / elastomers, produced by the commercially used melt grafting technology or the extremely uneconomical graft functionalization in liquid organic or aqueous phase or the solid phase graft functionalization without the addition of oil in the graft polymerization batch, as well as compared to the functionalized products obtained by these processes, which have only been oil-drawn after the functionalization reaction, by a significantly higher modifying effect. This is expressed above all - taking into account the accessibility of the broad backbone polymer range that can only be achieved by means of the solution according to the invention, particularly with regard to high-molecular TPE<maths id="math0002" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0805827B1_D0002.tif" /></maths>w ≥ 200,000) - even in the event of a sudden increase in toughness, in particular the notched impact strength values ​​at low temperatures (0 ° C. to approx. -50 ° C.), of the thermoplastic molding compositions finished with the graft-functionalized polymers according to the invention - while maintaining or even mostly increase the overall mechanical level (strength and stiffness and hardness parameters) and the heat resistance compared to the polymer molding compounds equipped with known comparable modifiers.

Since the desired modification effect is achieved when using, above all, the functionalized TPE according to the invention with significantly lower proportions, compared to the known TPE having approximately the same or similar degrees of functionalization, the use of the products according to the invention results in addition to those already achieved by oil stretching improved economy, additional cost savings. The broad selection of known olefinic homo-, saturated and unsaturated copolymers and block copolymers can be used as possible backbone polymers for the production of the functionalized polymers according to the invention. The most important polyolefins (PO) that can be used are:<ul id="ul0001" list-style="none"><li>Low density polyethylene (0.900-0.932 g / cm³), including small amounts (≤ 3% by mass) of higher olefins, according to the high pressure process (PE-LD);</li><li>linear low density polyethylene (0.915-0.935 g / cm³) using low pressure polymerization (PE-LLD) (H. Münstedt and H.-J. Walter, Kunststoffe 83 (1993) 10, pp. 725 - 728);</li><li>High density polyethylene (0.940-0.980 g / cm³) obtained by means of different low-pressure or medium-pressure polymerization processes, if appropriate using small amounts of higher olefins (PE-HD) (C. Gondro, Kunststoffe 83 (1993) 10, pp. 729-732);</li><li>Isotactic polypropylenes (PP), including the random or block copolymers obtained by polymerizing higher olefins, preferably produced by means of suspension (slurry), gas phase processes or a combination of bulk (bulk) and gas phase polymerizations, whereby in addition to the standard products, those which are technical Correspond to plastics in important properties and are traded under the name "PP based Advanced Materials" (PPAM), can be used (... Kunststoffe 83 (1993) 10, pp. 732 - 737);</li><li>further olefinic homopolymers, such as polybutene-1 (PB), polyisobutylene (PIB) and C₅- to C₁₂Polyolefins.</li></ul>

The main olefin copolymers are:

Nonpolar copolymers and terpolymers based on the polymerization of olefin mixtures, optionally with the addition of non-conjugated dienes (dicyclopentadiene, 5-ethylidene-2-norbornene, etc.), such as the elastomeric peroxide-crosslinkable ethylene / propylene copolymers (EPM) and the sulfur crosslinkable ethylene / propylene / diene terpolymers (EPDM), including the corresponding EP (D) M / PO (PE, PP) compounds, representatives of the TPE-O class (W. Hofmann, Kunststoffe 84 (1994) 2, S. 109-111; ibid. 80 (1990) 10, pp. 1204-1209, 1210-1212).

In addition to the non-polar olefin copolymers, polar olefinic copolymers composed of olefin and vinyl ester units and / or (meth) acrylic acid ester units can also be used as backbone polymers. The wide range of ethylene / vinyl acetate (VA) copolymers (EVA) with different compositions corresponding to VA contents of about 5 to 95% by mass, including the partial range of ethylene / vinyl acetate rubbers (EVM) with a VA- Content between about 40 and 80% by mass (H. Streib et al., Kunststoffe 67 (1977) 3, pp. 118-121; E. Rohde, Kautsch. + Gum.-Kunstst. 45 (1992) 12, pp. 1044-1051; K. Adler u. K. -P. Paul; Kunststoffe 70 (1980) 7, p. 411-418; DE 1126613, DE 1495660, DE 1495767, DE 2927088).

Furthermore, the ethylene / acrylate rubbers (AEM) composed of the broad EVA / EVM range, e.g. ethylene / ethyl acrylate (EEA), ethylene / n-butyl acrylate (EBA) and ethylene / (methyl) methacrylate copolymers ( EMA), are used as backbone polymers.

A relatively new and very promising olefin polymer product class with specifically controllable and variable microstructures and molecular weights has been developed by using metallocene catalysts, also referred to in terms of their action as "single-site" catalysts. (EP 0416.815; J. Okuda, Nachr. Chem. Tech. Lab. 41 (1993) 1, pp. 8-14; R. Mühlhaupt, Nachr. Chem. Tech. Lab. 41 (1993) 12, pp. 1341- 1351).

With the metallocene technology in particular olefin copolymers of ethylene (propylene) and higher α-olefins, preferably octene, the proportion of which in the reactor via the number of C₆-Side chains decides to be preserved. As backbone polymers according to the present invention, various olefin copolymers of this new product class which are already commercially available or which are about to be launched on the market can preferably be used. This applies in particular to the copolymers obtained from predominantly ethylene and up to a maximum of 20% from octene, known under the name of polyolefin plastomers (POPs), and the corresponding “softer” copolymers with more than 20% octene and as polyolefin elastomers (POEs) designated, furthermore the cycloaliphatic olefin homo- and copolymers as well as styrene / ethylene copolymers with a high styrene content and high molecular weight and also - analogously to syndiotactic polystyrene (SPS) - the syndiotactic polypropylene (SPP) (J. Wolters, Kunststoffe 83 (1993) 12, pp. 985-987).

Another group of usable backbone polymers are the partially crystalline thermoplastic block copolymers that are on the market in contrast to the amorphous POPs and POEs. They consist of crystalline (hard) PO blocks, mostly PE blocks with melting temperatures of about 95 to 110 ° C, and amorphous ( soft) PO blocks with glass transition temperatures between -40 and -60 ° C.

Ultimately, chlorinated polyethylenes (PE-C, CM) and chlorosulfonated polyethylene rubbers (CSM) can also be used as backbone polymers or backbone polymer components.

In general, the backbone materials are compounds consisting of at least two different olefinic thermoplastics and / or (crosslinked or uncrosslinked) elastomers, optionally with the addition of a fibrous or particularly particulate filler from the range of known assortments in the usual concentrations of approx. 5 to 100 parts by weight, preferably from 10 to 50 parts by weight, based on 100 parts by weight of polymeric backbone material, can be used.

The olefinic / vinylaromatic block copolymers occupy a preferred position as usable backbone materials. They are obtained by selective hydrogenation (GB 1030306, US 3700633) of differently structured (linear and radial) block copolymers from monovinyl-substituted aromatic hydrocarbon segments (polyvinylaryl blocks), preferably from styrene or blocks composed of alkylated and / or halogenated styrenes (S), and conjugated diene segments, preferably composed of blocks (B or I) composed of butadiene (1,3) or methylbutadiene (1,3) (isoprene), the different blocks can be sharply separated from one another or can have “smeared” transitions (tapered section), with olefinic unsaturation levels of generally ≤ 20%, preferably ≤ 5%.

The styrene / ethylene-butylene / styrene triblock copolymers (SEBS.) Obtained by selective hydrogenation of styrene / butadiene / styrene triblock copolymers (SBS), the butadiene center block of which has a vinyl group content of between 10 and 80%, preferably between 25 and 65%, are particularly suitable ) and the corresponding styrene / ethylene-propylene / styrene triblock copolymers (SEPS) obtained from the styrene / isoprene / styrene three-block copolymers with weight-average molecular weights <maths id="math0003" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0805827B1_D0003.tif" /></maths>w between 20,000 and 1,000,000.

Due to the thermodynamically incompatible phase behavior between the hard fusible vinylaryl blocks and the soft elastic polydiene or polyolefin blocks, these three and possibly multi-block copolymers are typical TPE (TPE-S coded as polystyrene-containing TPE). The group of TPE-S, which can be used particularly inexpensively in the form of backbone polymer compounds, mainly includes SEBS / PO or SEPS / PO blends, whereby PP, PE-LD, PE-LLD and EPM are preferably suitable as PO components and the compounds can optionally also contain a filler content for the purpose of adjusting certain hardness levels while at the same time achieving a cost reduction. The basic morphological characteristics of the TPE-S are not or only slightly changed by the polymeric and / or inorganic additives mentioned.

In general, fibrous and particularly particulate fillers can be added in an amount of up to approx. 70% by mass, preferably between 5 and 50% by mass, with, in addition to the preferred spherical calcium carbonates, in particular chalks, optionally also platelet-shaped potassium aluminum silicates , such as mica, feldspar and kaolin, or magnesium silicates, such as talc, and acicular calcium silicates, such as wollastonite, can be used. In addition to the olefinic backbone polymers mentioned, unsaturated backbone polymers based essentially on copolymerized diene units, some of which are already mentioned among the olefin copolymers, can also be used for the production of functionalized polymers according to the invention, in particular olefin interpolymers such as, for example uncrosslinked EPDM, and styrene / conjugated diene three-block copolymers (SBS, SIS) as well as the corresponding two-block copolymers (SB, SI) and multiple block copolymers, with different structures, symmetrical or asymmetrical, linear and star-branched (radial) structure (GB 985614, DE 2125344, DE 1959922, US 3281383), the block copolymers having only sharp transitions between the segments or "smeared", ie essentially contain statistical copolymer segments (tapered section) (DE 2550226, DE 2550227, GB 888624, GB 1044862, NL 6713383).

The vinyl group content of the segment unit formed from the conjugated diene can be 10 to 80%, preferably 25 to 65%. The weight average molecular weight <maths id="math0004" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0805827B1_D0004.tif" /></maths>w of the styrene / diene block copolymers is between 20,000 and 1,000,000, preferably between 50,000 and 500,000. Each PS block S can have the same or a different number average molecular weight <maths id="math0005" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0805827B1_D0005.tif" /></maths>n from 4,000 to 100,000 and each polydiene block B or I. <maths id="math0006" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0805827B1_D0006.tif" /></maths>n have between 10,000 and 200,000.

Polydienes and statistical diene elastomers, in particular the commercially available butadiene rubbers (BR), natural rubbers (NR), isoprene rubbers (IR), butyl rubbers (IIR), styrene / butadiene rubbers (SBR), acrylonitrile / butadiene rubbers, (NBR), can also be used as backbone polymers. Chloroprene rubbers (CR) and the like, including the corresponding hydrogenated rubbers (H-BR, H-NBR, etc.) can be used.

In addition, the by grafting olefinic and / or vinyl group-containing monomers, especially styrenes, (meth) acrylonitrile and (meth) acrylates, on diene rubbers and olefin or Acrylate rubbers obtained top graft polymer products, such as those corresponding to the monomer combinations acrylonitrile / butadiene / styrene (ABS), methyl methacrylate / butadiene / styrene (MBS), methyl methacrylate / acrylonitrile / butadiene / styrene (MABS) and acrylate / styrene / acrylonitrile according to the invention (ASA) suitable backbone polymers. The thermoplastics and elastomers, in particular TPE, used as backbone polymers are graft-functionalized using the following preferred functional monomers:<ul id="ul0002" list-style="none"><li>1.) which have at least one mono- or dicarboxyl group or a group derived therefrom (corresponding derivatives), in particular an anhydride group, representative of this class of compounds being acrylic acid (AS), methacrylic acid (MAS), fumaric acid (FS) and maleic anhydride (MSA ) and the corresponding higher molecular weight homologues are to be mentioned,</li><li>2.) which have at least one epoxy or hydroxy group, glycidyl methacrylate (GMA), hydroxyethyl acrylate (HEA) and hydroxypropyl methacrylate (HPMA) being representative of this class of compounds,</li><li>3.) which have at least one aminic, amidic or imidic group (both of the latter can also be classified as derivatives of the above 1st functional monomer class), acrylamide and 2-dimethylaminoethyl methacrylate (DMAEMA) being typical representatives of this class of compounds, and</li><li>4.) which have at least one silane group, such as (y-methacryloyloxypropyl) trimethoxysilane and especially tris (2-methoxyethoxy) vinylsilane as selected representatives of this type of functional monomer.</li></ul>

Functionalization - generally up to a maximum of about 33% by mass of functional monomer grafted on - is of course also possible with the monomers which have two or more different polar functional groups.

After the graft functionalization has taken place, secondary reactions on or via the grafted-on functional groups, such as, for example, a free-radical reaction or, in particular, reaction with metallic salts or hydroxides, an ionic crosslinking reaction (EP 0086159) and also a subsequent reaction of the functional groups with low-molecular substances can react with the grafted polar groups, such as with an N-substituted imide, amide or N-substituted hydroxyethyl monomer (EP 0128775) or with bis- or tris-carbodiimides (US 4,689,372).

The functional monomers can be used alone or also as a mixture of two or more functional monomers and, advantageously, with the addition of one or more comonomers which preferably have no reactive functional groups or only significantly weaker polar groups, such as, for example, ester groups.

Especially by using styrene as a comonomer, the mass ratio of functional monomer to comonomer being able to be varied within a very wide range, preferably from 90 to 10% to 10 to 90%, independently of the other selectable grafting process and product parameter control variables, such as Initiator type and concentration, Ratio of the monomer to the backbone polymer content and, last but not least, the oil content that can be added within wide limits - important application properties of the functionalized polymers are significantly influenced. The process oil plays a central role in the graft polymerization process and the functionalized graft product. For the functionalized thermoplastics and elastomers according to the invention, a large number of different oils which have been added to the backbone polymer or polymer compound (unfilled / filled) before the graft functionalization stage - if appropriate in a special pre-compounding stage - have proven to be suitable. This applies primarily to the well-known, highly refined, high-boiling mineral oils, preferably those with a paraffinic and / or naphthenic but possibly also aromatic structure, generally not decomposing below 300 ° C, clear and odorless, without toxic components (suitable for the food sector). Furthermore, taking into account the intended special intended use, including the use of the functionalized products in the various thermoplastic molding compositions, native oils, such as especially the known vegetable oils (rapeseed oil, soybean oil, etc.), can also be used as a component according to the invention in the graft polymerization batch.

The known organic peroxides and diazo compounds, including corresponding initiator mixtures, with a ten-hour half-life temperature (measured in 1.0 m benzene solution) between 40 ° C. and 90 ° C., preferably the known diacyl peroxides, such as dilauroyl peroxide ( DLPO) and dibenzoyl peroxide (DBPO), dialkyl peroxidicarbonates and perneodecanoates.

The entire graft polymerization batch, consisting of backbone polymer (compound), oil component, monomer (s) (functional monomer and optionally additional comonomer) and radical initiator, is initially introduced into the reactor at room temperature, in which the reaction mixture, in a first, generally ten-minute to half-hour, dispersion phase, essentially in an almost dry to "oil-moist" powdery and / or crumbly and / or flaky or scale-like to flaky and / or coarse-grained (granular) state, is brought into a form favorable for graft polymerization.

At this point, it should be pointed out that for the purpose of improving the dispersing action - as well as for possible pre-compounding stages (e.g. mixing the backbone polymer, optionally with the addition of a second polymer and / or a filler, with the oil,) - work is carried out in an inert water medium can, the inert water content between 20 and 500 parts by mass, based on 100 parts by mass of solid / oil, can be selected.

In principle, the subsequent stage, the actual graft functionalization, can also be carried out in the presence of inert water as the dispersing auxiliary medium and / or additional heat transfer and heat dissipation medium (taking into account the specific reactor design, including the stirring device), without fundamentally changing the grafting process.

In the second phase, the reaction phase, generally a period of between 1 and 10 hours, preferably between 2, is maintained in compliance with a temperature-time regime which is dependent on the reaction components and the final reaction temperature with which the radical initiator selected also corresponds and 5 hours, the chemical grafting reaction was carried out.

A characteristic feature of this type of solid phase grafting - without the possible addition of inert water mentioned above - is the maintenance of the dry to possibly oil-moist consistency of the reaction medium.

Functionalization levels that are particularly advantageous in terms of technology and product have been the use of 0.2 to 10 parts by weight of AS and / or MAS and / or MSA or GMA or HPMA as functional monomers, based on 100 parts by weight of backbone material, and of graft monomer mixtures from the corresponding Functional monomers and a non-polar or Comonomers having less reactive polar groups, preferably styrene and / or α-methylstyrene and / or an alkyl (meth) acrylate with a functional / comonomer mass ratio of 1 to 5 to 5 to 1, have been obtained.

Because of their excellent adhesive properties, the functionalized polymers according to the invention can be used as coatings on different substrates, in laminates and the like (adhesives). The main use - both for economic reasons and because of their particularly high effectiveness - is that as impact modifiers for a large number of thermoplastics, in particular for a number of the most important technical and high-performance plastics.

Embodiment

Production of the functionalized polymers

100 parts by mass of a polymer or polymer compound from the series of the backbone polymers summarized in Table 1, each of which contains a certain proportion of a process oil (oil characteristic values ​​in Table 2) specified in Table 1, are placed in a temperature-controlled reactor equipped with a stirring device and oxygen-free rinsed , submitted. At room temperature the monomer or Monomer mixture (functional monomer and additional comonomer) corresponding to the species and proportions listed in Table 3 together with the free radical initiator, in most cases a diacyl peroxide for polymerization end temperatures Tpm from 70 to 90 ° C, optionally for lower Tpm (55 to 75 ° C) also a dialkyl peroxidicarbonate or a diazo compound.

In addition to the backbone polymers and oils listed in Tables 1 and 2, the following feedstocks were used:

Functional monomer

Acrylic acid (AS), maleic anhydride (MSA), hydroxypropyl methacrylate (HPMA), glycidyl methacrylate (GMA), 2-dimethylaminoethyl methacrylate (DMAEMA) and tris (2-methoxyethoxy) vinyl silane (V-silane)

Additional comonomers

Styrene (S), α-methylstyrene (MS) and ethyl acrylate (EA)

Initiators

Mostly dibenzoyl peroxide and dilauroyl peroxide in concentrations between 0.1 and 3%, preferably between 0.2 and 1.5%, based on the backbone polymer mass, in some cases also dicetyl peroxidicarbonate or 2,2-azo-bis (isobutyronitrile) within the concentration range mentioned .

filler

Chalk (coated) with an average particle diameter of 2.5 µm (contained in the backbone polymer compound) (see Table 1).

After the feed substances (dispersion phase) have been mixed for about 30 minutes, the functionalization of the backbone polymer (reaction phase) takes place in accordance with a temperature-time program which is dependent on the individual concentrations of the graft polymerization batch and is generally fixed over 2 to 5 hours. The reaction is terminated after reaching a monomer conversion, which is between 50 and almost 100% depending on the respective grafting system, by cooling the reactor, flushing with nitrogen (if necessary separate recovery of unreacted and expelled residual monomers) and emptying. The graft products, which are mostly free of monomers, are characterized directly by analysis (see Table 3).

The following are determined:<ul id="ul0003" list-style="dash"><li>Degree of functionalization FG (percentage mass fraction of polymerized functional monomer, based on the total graft product polymer mass), determined by back titration with 0.1 molar HCl of the 0.1 molar potassium hydroxide solution not neutralized by the carboxylic acid content (AS, MSA) or by elemental analysis of the oxygen ( Control determination AS and MSA and exclusively for HPMA and GMA), nitrogen (for DMAEMA) and silicon (for V-silane);</li><li>Gel content m_gel as a measure of the degree of crosslinking, ie the insoluble fraction of the functionalized polymer determined in boiling xylene and given in mass%.</li></ul>

Table 3 shows the backbone systems (backbone polymer or polymer compound / oil additive) taken from Table 1 with the serial numbers given in column 1 of Table 1. No. (1 to 70) listed. In addition, some representative comparison products (see No. / column 1 of Table 3) are given, which each have the same product number. - but manufactured without the addition of oil. In addition, the technology used to obtain the comparison products - either by means of analog solid-phase grafting without oil (FP) or by melt grafting (SP, 190-210 ° C. / twin-screw extruder). An essential characteristic of the graft products is their degree of functionalization (FG).

After separation of the copolymer fractions formed from the functional monomers or from functional / comonomer mixtures by fractional precipitation, the grafting yield can be seen as the ratio of the mass of grafted functional monomer to the total polymerized functional monomer mass or the degree of grafting as that on the backbone polymer mass related grafted functional monomer mass can be determined.

Particularly high grafting yields (≥90%) are obtained for the olefinic backbone polymers, in particular PE-LD, EPM, EVA, SEBS, SEPS or SEPS / PO compounds, which correspond to the grafting formulation according to the invention (oil content, type and concentration of the monomers and the Initiators) lead to functionalized polymers with highly effective modifier properties.

On the basis of the gel content given as the second important characteristic value in Table 3, it can be seen that, if the grafting system consisting of graft backbone / oil and functional monomer / additional comonomer is chosen accordingly, gel-free systems (m_gel ≤ 5%) or low-level functionalized graft products (m_gel ≤ 20%) can be obtained (exception: only PE-LD backbones). On the other hand, it is also possible to produce functionalized polymers with a high gel content.

In this connection, it should be pointed out once again that the graft technology according to the invention and the functionalized polymers obtained therewith have the advantage that particularly high molecular weight backbones (<maths id="math0007" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0805827B1_D0007.tif" /></maths>w&gt; 200,000), such as, for example, the styrene / olefin / styrene three-block copolymers which are of technical interest for the present invention (see in particular the SEPS used or the corresponding SEPS compounds as the backbone), which are caused by the addition of oil and then by the use of solid phase grafting technology brought into a neat, graftable form and can be functionalized without any technical-technological difficulties (among other things no reactor inner product approaches / graft products with a very uniform particle shape).

Furthermore, the technology according to the invention discloses further advantages, which were also taken into account, inter alia, in the individual examples in Table 3. Thus, especially when using MA as a functional monomer, without an additional comonomer being present in excess, significantly higher graft yields are obtained due to the oil content (approx. 70-80% compared to 50 to a maximum of 60% without oil in the graft batch). Analogously, the oil content according to the invention - in contrast to the addition of oil in the same concentration after the graft functionalization has taken place - causes a reduction in the gel content m_gel, which is otherwise achieved by increasing the proportion of comonomer, in particular in the form of a considerable excess of styrene. Higher proportions of styrene, in turn, generally lead to a lower backbone functionality and thus a lower adhesive effect (adhesiveness) or limited modifier effectiveness, especially in molding compositions (blends, composites) based on polar thermoplastics. On the other hand, however, the technology according to the invention allows functionalization with a very clear excess of additional comonomers, in particular styrene, for the purpose of producing only very little or, in the extreme case, non-functionalized, styrene-grafted olefinic and / or diene backbone polymers. The graft polymer products obtained in this way, which practically have a graft PS block structure, include Particularly suitable for the modification of blends based on PS / PO and possibly other thermoplastics.

Production of the ionically crosslinked functionalized polymers

The neutralization and thus the ionic crosslinking of some of the carboxylated polymers or polymer compounds listed in Table 3 was carried out using conventional extrusion technology (see also US 3,969,434) using a salt combination of ZnO, Zn acetate and Zn stearate (in the form of a concentrate previously produced from 50% by mass carboxylated polymer and 50% by weight salt combination) corresponding to a Zn cation concentration, which permitted a degree of neutralization of the grafted-on acrylic acid between 30 and 80 mol% in a Brabender plastograph (see information in Table 4). The ionic crosslinking reaction was carried out analogously using KOH (see also US Pat. No. 4,308,353). Using a 43 mm twin-screw extruder (L = 38 D) with a degassing zone, a selected carboxylated TPE using Mg (OH)₂ ionically cross-linked (see also US 4,666,988, US 4,774,290). Table 4 lists the ionically crosslinked functionalized polymers obtained in this way, including two comparative ionomers prepared without oil in the graft-functionalization approach.<tables id="tabl0001" num="0001"><img file="EP0805827B1_D0008.tif" /></tables><tables id="tabl0002" num="0002"><img file="EP0805827B1_D0009.tif" /></tables><tables id="tabl0003" num="0003"><img file="EP0805827B1_D0010.tif" /></tables><tables id="tabl0004" num="0004"><img file="EP0805827B1_D0011.tif" /></tables><tables id="tabl0005" num="0005"><img file="EP0805827B1_D0012.tif" /></tables><tables id="tabl0006" num="0006"><img file="EP0805827B1_D0013.tif" /></tables><tables id="tabl0007" num="0007"><img file="EP0805827B1_D0014.tif" /></tables><tables id="tabl0008" num="0008"><img file="EP0805827B1_D0015.tif" /></tables><tables id="tabl0009" num="0009"><img file="EP0805827B1_D0016.tif" /></tables><tables id="tabl0010" num="0010"><img file="EP0805827B1_D0017.tif" /></tables><tables id="tabl0011" num="0011"><img file="EP0805827B1_D0018.tif" /></tables><tables id="tabl0012" num="0012"><img file="EP0805827B1_D0019.tif" /></tables><tables id="tabl0013" num="0013"><img file="EP0805827B1_D0020.tif" /></tables><tables id="tabl0014" num="0014"><img file="EP0805827B1_D0021.tif" /></tables>