WO2003037942A1

WO2003037942A1 - Particulate, partially or fully cross-linked rubber and the use of the same

Info

Publication number: WO2003037942A1
Application number: PCT/EP2002/012122
Authority: WO
Inventors: Graham Edmund Mckee; Helmut Schmiedberger; Christian Lach
Original assignee: Basf Aktiengesellschaft
Priority date: 2001-10-30
Filing date: 2002-10-30
Publication date: 2003-05-08
Also published as: DE10153386A1; TW200302834A; EP1448637A1

Abstract

The invention relates to a particulate, partially or fully cross-linked rubber having a glass transition temperature which is lower than 0 °C. Said rubber has cross-linking points which are interconnected by network arcs having a mean molecular weight of between 10,000 g/mol and 50,000 g/mol. According to the invention, the average nuclear magnetic transversal relaxation time (T2m) of the rubber protons is between 3 and 15 ms, when measured at a temperature of 140 °C, and has an at least bimodal relaxation time distribution (h(T2)). A first fraction, representing at least 70 %, has a mean transversal relaxation time (T2s) of between 2 and 10 ms. The inventive rubber is preferably used as an impact-resistant modifier for moulding materials, in a grafted or non-grafted form.

Description

Particulate, partially or fully crosslinked rubber and its use

The present invention relates to a particulate, partially or fully crosslinked rubber and the use thereof, in grafted or ungrafted form. Such rubbers can be used, for example, to increase the notched impact strength of thermoplastic or thermosetting molding compositions, but also for other purposes. The invention also relates to a method for producing such a rubber and a method for checking such rubbers or derived products made from these rubbers.

The impact resistance of plastics is usually increased by adding elastic components to the polymer matrix. The addition can also be carried out, for example, by copolymerization or graft polymerization. For example, elastic polymers are used to increase the impact strength of thermoplastic or thermosetting molding compounds. Such impact-modified molding compounds are used to produce molded parts for a wide variety of applications, for example for household items, motor vehicle components, housings for electrical appliances, toys and sports articles, pipes, etc.

So-called ABS polymers are widely used, for example, in which the impact strength of styrene / acrylonitrile copolymers is increased by incorporating a butadiene rubber. This is generally done by graft copolymerization of styrene and acrylonitrile in the presence of the rubber, and, if appropriate, by subsequent mixing of this graft product with a separately produced hard component which generally consists of a styrene / acrylonitrile copolymer. Such a thermoplastic molding composition is described, for example, in European patent application EP 0 022 200 AI. The rubber is incorporated in the form of particles in a matrix formed by the hard component. According to EP 0 022 200 AI, ABS molding compositions with improved impact strength at lower temperatures and good gloss are obtained if, as an impact modifier, a graft copolymer with polybutadiene as the graft base and a graft shell made from styrene and acrylonitrile is used in the form of particles which have an average particle diameter from 0.2 to 0.45 µm (dso value of the integral mass distribution), the transverse nuclear magnetic relaxation time (T _2m relaxation time) of the insoluble fraction isolated from the molding composition being 0.7 to 1.5 ms. However the impact strength of the rubbers at higher temperatures is still unsatisfactory for many applications.

ABS plastics are sensitive to sunlight and weathering due to the double bond contained in the butadiene polymer. Therefore, impact modifiers which are produced on the basis of double-bond-free or low-double-bond rubbers are often used, in particular for areas of use in which the molded parts produced from impact-modified molding compositions are exposed to environmental influences. Examples here are, in particular, polymers based on an alkyl acrylate, in particular based on n-butyl acrylate or 2-ethylhexyl acrylate. The corresponding particulate chewing-elastic polymers which can be used without grafting or grafted as impact modifiers are typically composed of a component ai) 50-100% by weight of an alkyl acrylate with an alkyl radical of

1-30 carbon atoms, and a component a ₂ ) 0-50 wt.% By weight of at least one further monomer which can be copolymerized with ^a ι). The glass transition temperature of such a polymer should be lower than 0 ° C, preferably lower than -15 ° C.

in the present context, the term “glass transition temperature” means the glass transition temperature determined by the DSC method (differential scanning calorimetry, 20 ° C./min, midpoint) (see ASTM D 3418-82). The person skilled in the art will use a suitable monomer mixture to set the desired glass transition temperature when producing a corresponding polymer. According to Fox (TG Fox, Bull Am. Phys. Soc. (Ser. II) 1, 123 [1956] and Ullmann's Encyclopedia of Industrial Chemistry, 4th edition, Volume 19, Verlag Chemie, Weinheim (1980), pages 17, 18) applies to the glass transition temperature T _g of copolymers with large molar masses in good nutrition

τ _g τ ⁺ τ - τ \ where X ¹ , X ² , ..., X ^{n are} the mass fractions of the monomers 1, 2, ..., n and T ¹ _g , T ² _g , ... T ⁿ _g the Glass transition temperatures of the polymers built up in each case from one of the monomers 1, 2,..., N in degrees Kelvin. The glass transition temperatures of homopolymers are known to the person skilled in the art, for example from Ullmann's Encyclopedia of Industrial Chemistry, 50th Edition, VDH, Weinheim, Volume A 21 (1992) page 169 or J. Brandrup EH Immergut, Polymer Handbook, 2nd Edition, J. Wiley, New York 1975, pages 139-192.

Such particulate alkyl acrylate rubbers are already used as impact modifiers for acrylonitrile-styrene copolymers. These systems are known under the name ASA and consist of a poly (styrene-acrylonitrile) matrix (PSAN) which contains, for example, polybutyl acrylate particles which are preferably grafted with polystyrene-acrylonitrile. However, the impact strength of the known copolymers is not yet sufficient for special areas of application.

The present invention is therefore based on the technical problem of providing novel, particulate, partially crosslinked rubbers which enable the production of thermoplastic and thermosetting molding compositions with significantly higher impact strength.

So far, the search for suitable impact modifiers has been extremely tedious and time-consuming. First of all, a large number of different rubbers had to be manufactured. The rubber particles were then grafted in most cases and then incorporated into a thermoplastic or thermosetting matrix under defined conditions. Suitable test specimens were then produced from the resulting molding compound and tested mechanically. It was only on the basis of the results of the mechanical tests on the test specimens that it was possible to assess whether or not certain rubber particles led to an improvement in the impact strength of the molding compositions.

The present invention is based on the surprising finding that particulate, partially crosslinked rubbers, the polymeric network of which are arcs, i.e. Polymer chains between adjacent crosslinking points, with a certain minimum length and a certain mobility, when incorporated into a thermoplastic or thermosetting matrix lead to a particularly strong increase in impact strength, in particular the notched impact strength of the resulting molding compositions.

The present invention therefore relates to a particulate, partially or fully crosslinked rubber with a glass transition temperature which is lower than 0 ° C., the rubber having crosslinking points which are connected to one another by network arches. The rubber according to the invention is characterized in that the average molecular weight of the mesh sheets is between 10,000 and 50,000 g / mol. This is preferably average molecular weight of the mesh sheets between 13,000 and 40,000 g / mol and particularly preferably between 14,000 and 30,000 g / mol.

For given monomers, the average molecular weight of the mesh arches is a measure of the mesh arch length. Various methods are known for estimating the network arc length of a polymer network, for example swelling tests. However, the network arc length is preferably determined using nuclear magnetic resonance methods, as will be explained in more detail below. Nuclear magnetic methods, in particular a determination of the so-called transverse relaxation time T _2, are particularly suitable because these methods also allow statements about the mobility of the network arcs. It has been found that a particularly significant increase in impact strength can be determined if the mesh arches have a mobility which can be described by a transverse relaxation time (T _2m ) of ¹ H-nuclei of the rubber, which is in the range from 3 to 15 ms , The relaxation time must be determined at a temperature which is above the NMR glass transition temperature T _g 'of the rubber, the NMR glass transition temperature being defined as the start of the steep rise in a T ₂ (T) diagram. Because of the effective frequency in the kHz range, T _g 'is shifted to higher temperatures in comparison to the statically determined glass transition temperature T _g . Accordingly, the relaxation time should be determined at a sample temperature of at least 30-50, but preferably more than 80 ° C. above the static glass transition temperature T _{g of} the rubber. It is particularly preferred to measure at a temperature of more than 100 ° C. above the static glass transition temperature, because in this temperature range, also referred to as the T ₂ plateau, the measured T ₂ relaxation times only increase slightly with increasing temperature.

The present invention therefore also relates to a particulate, partially crosslinked rubber with a glass transition temperature which is lower than 0 ° C., which is characterized in that a relaxation of a transverse magnetization of ^ cores of the rubber by a transverse relaxation time (T _2m ) is writable, which is in the range of 3 to 15 ms when measuring at a temperature of 140 ° C.

However, according to the invention, particular preference is given to rubbers which are in the claimed range both in terms of the length of the mesh arch and in terms of the transverse relaxation time. The person skilled in the art is familiar with the determination of the transverse nuclear magnetic relaxation time (which is also referred to as spin-spin relaxation time). The hydrogen nuclei ( ¹ H nuclei) of the polymer chains serve as molecular probes. For this purpose, a sample of the material is placed in a static magnetic field, which imparts a preferred direction to the nuclear spins of the hydrogen nuclei. After resonant excitation with high-frequency pulses, magnetization is generated perpendicular to the preferred direction defined by the static magnetic field. Due to the dipolar interaction of the hydrogen nuclei with each other, the transverse magnetization decreases over time. The time in which the magnetization has dropped to the e-th part of its initial value corresponds to the transverse relaxation time T. In the simplest case, the decay of the transverse magnetization can be described by an exponential function with a time constant T ₂ . The relaxation process in polymer networks usually shows a more complex behavior that can no longer be described by a simple exponential function. An analysis of the measured relaxation curve of the transverse magnetization can then be described by a distribution of T ₂ values. For example, in the case of an essentially biexponential relaxation drop, a bimodal T ₂ distribution is obtained. The time in which the transverse magnetization drops to the e-th part of its initial value therefore corresponds to an average of the different transverse relaxation times and is referred to in the present application as T _2m .

It is known that the transverse relaxation time in polymer networks enables statements to be made about the chain dynamics and the crosslinking density, since the crosslinking points limit the range of practically feasible chain conformations and thus prevent isotropic averaging of the dipolar interaction between the hydrogen nuclei. The transverse relaxation time T _2m therefore represents an averaged measure of the movement of the polymer chains. The transverse relaxation time T _2m found according to the invention in the range of 3-15 ms surprisingly corresponds to a network topology of the rubber particles which leads to a particularly advantageous increase in the impact strength of lead thermoplastic and thermosetting molding compounds.

Numerous advantages are associated with the characterization of the polymer according to the invention by the transverse nuclear magnetic relaxation time: Nuclear magnetic (NMR) relaxation measurements are characterized by a short measuring time, good reproducibility availability and ease of use of the measuring instruments. NMR investigations generally have no special requirements for the consistency and shape of the samples. A particular advantage of the present invention proves, however, that it is possible 5 to test the ungrafted rubbers for their suitability as modifiers for increasing the impact strength of molding compositions. It has been shown that the advantageous properties as impact modifiers are determined crucially by the ungrafted polymer. On the one hand, if the measured

If the relaxation times of the ungrafted polymer are not in the range recognized as advantageous according to the invention, the subsequent grafting step does not lead to satisfactory results either. In many cases, one can therefore dispense with complex further processing stages. On the other hand, a

15 g of the graft copolymer composed of the particulate, rubber-elastic polymer according to the invention would be particularly advantageously suitable as an impact modifier for thermoplastic or thermosetting molding compositions.

The present invention therefore also relates to a graft copolymer prepared by grafting 0.1 to 99.9% by weight, preferably 5 to 95% by weight and particularly preferably 10 to 90% by weight of a graft base consisting of the particulate according to the invention , partially or fully cross-linked chewing

25 chuk with 0.1 to 99.9% by weight, preferably 5 to 95% by weight and particularly preferably 10 to 90% by weight of graft monomers. The graft monomers preferably consist of styrene, acrylonitrile, an ester of (meth) acrylic acid or a mixture of these monomers.

30

The present invention also provides the use of teilchenformigen, partially or fully crosslinked rubber of the invention and / or the Propfmischpolymerisats according to the invention for the modification of Kunststoffformmasssen, in particular for ER- 3 ₅ notched impact resistance heightening of thermoplastic or thermosetting molding compositions.

The present invention finally also relates to a thermoplastic or thermosetting molding composition containing 1 to

40 99 parts by weight, preferably 5 to 95 parts by weight and particularly preferably 10 to 90 parts by weight of a thermoplastic or thermosetting polymer as a matrix, 1 to 99 parts by weight, preferably 5 to 95 parts by weight and particularly preferably 10 to 90 parts by weight of the particulate

45 genes, partially or fully crosslinked rubber and / or the graft copolymer according to the invention, and up to 50 parts by weight of conventional additives, the non-isolated from the molding composition soluble portion has a transverse relaxation time (T _2m ), which is in the range of 3 to 10 ms when measured at a temperature of 140 ° C.

Depending on the composition, the molding compositions according to the invention can have notched impact strengths at 23 ° C. of more than 40 kJ / m ² , particularly preferably more than 50 kJ / m ² . The notched impact strength is measured in accordance with ISO 179 with an Izod test specimen which has dimensions of 4 mm × 10 mm × 79.2 mm and which is produced by injecting the molding compound at a temperature of 270 ° C. into a mold heated to 50 ° C. becomes. The notched impact strength given here relates to a molding composition according to the invention which contains no additives. However, the molding composition preferably contains up to 50 parts by weight of conventional additives. Certain additives, for example glass fibers, can have a negative impact on the notched impact strength, so that molding compositions according to the invention which contain such additives can also have a lower notched impact strength than the aforementioned 40 kJ / m ² .

The invention also relates to molded parts made from such molding compositions.

The particulate rubber according to the invention is particularly preferably not characterized by a single transverse relaxation time, but by a relaxation time distribution h (T ₂ ), the relaxation time T ₂ usually being scaled logarithmically, that is to say h (lnT ₂ ). The invention is based on the consideration that the real polymer network (gel) of the acrylic rubber has network arches, that is to say polymer chains between adjacent cross-linking points, of different lengths, the different mobility of which is also reflected in different relaxation times. There are also so-called free chain ends, ie polymer chains that only end at a crosslinking point, as well as shorter chain segments and monomers that are not integrated in the network. The free chain ends and the free chain sections (sol) are characterized by a particularly high degree of mobility and, accordingly, also by long T ₂ relaxation times. It has now been found that the polymer, which is suitable as a basis for a particularly pronounced increase in the impact resistance of thermoplastic or thermosetting molding compositions, has an at least bimodal relaxation time distribution h (lnT), a first fraction, the proportion of which at least 70% based on the The number of hydrogen cores is, has an average transverse relaxation time T _2s in the range from 2 to 10 ms, preferably from 2.8 to 10 ms and particularly preferably from 3.0 to 8 ms. One assumes that this first fraction is defined by the mobility of the polymer chains fixed by two cross-linking points, ie the so-called network arches. The second, more mobile fraction, which to a certain extent reflects the defects in the polymer network, such as free chain ends and sol, has an average transverse relaxation time T _2f of more than 10 milliseconds. Their share is advantageously at most 15%. The indices "s" or "f" stand for "slow" or "fast" and denote the less mobile (slow) or the more mobile (fast) fraction.

To determine the distribution of the transverse relaxation times, the person skilled in the art can again use numerous NMR methods known per se. So-called Hahn 'see spin echo methods are used particularly advantageously, in which the original free induction decay FID (Free Induction Decay) is refocused with the aid of high-frequency pulse sequences after a certain development time. The T ₂ distribution sought is determined from the experimental NMR data using numerical methods. The distribution function h (InT ₂ ) is essentially determined by an inverse Laplace transformation with the aid of a predefined basic function from the time profile of the magnetization M (t). In the present case, an exponential function exp (-t / T ₂ ) is advantageously chosen as the basic functions. It is assumed that the polymer is so flexible that a purely exponential T ₂ decay results for each individual chain. This requirement can be approximated experimentally by carrying out the relaxation measurement significantly above the glass transition temperature of the rubber, for example at about 140 ° C. in the case of the polymers according to the invention. The numerical problem can be traced back to the solution of a first-order Fredholm integral equation from noisy experimental data. Commercial software packages are available to solve the problem. The FTIKRG (Fast Tikhonov Regulatory) program from Scientific Consulting Group GmbH, Freiburg, is one example. A more detailed description of the underlying numerical method can be found, for example, in Continuum Mechanics and Thermodynamics 2 (1990) 17-30 and Computer Physics

Communications 69. (1992) 99-111.

From the mean transverse relaxation time T ₂ one can calculate the mean length of the network arc between two neighboring network points. In the so-called T ₂ plateau, ie when the sample temperature is at least 100 ° C above the glass transition temperature, the average number of statistical segments z between two network points can be calculated as where a = 6.2 ± 0.1 is a theoretical value for aliphatic protons of the main chain and T _{2r is} the T ₂ value of the swollen sample below the glass transition temperature (see Fry et al., Macromolecules 21 (1988), 1292). The average molecular weight can then be determined according to Simon et al., Macromolecules 25 _. (1992), 3624-3628 calculate as ^M c = M _U zcn < ^χ T ₂ where M _{u is} the molecular weight of a monomer unit, c _∞ the number of main chain bonds of a statistical segment and n the number of bonds in the main chain. T _2s only takes into account chains that form mesh arches (gel), while mesh defects contribute to T _2f . The effective net arc length of the gel fraction can then be determined from T _2s as z = ^ and the average molar mass of the net arcs as

M _c g / mol] = M _U zc _∞ / n ~ 5505 T ^ [ms].

According to the invention, the mean network arc length of the polymer according to the invention is advantageously more than 10,000 g / mol, preferably more than 13,000 g / mol and particularly preferably more than 14,000 g / mol.

It was surprisingly found that the grafting of the rubber and the subsequent incorporation into the hard matrix did not significantly change the T ₂ relaxation times described above. In general, after the base rubber has been grafted, T ₂ relaxation times are reduced by up to 20% and the length of the net arch is correspondingly shorter. The T _2m relaxation time of the grafted rubber is advantageously 2.7 to 10 ms, preferably 2.8 to 10 ms and particularly preferably 2.9 to 8 ms. In the case of the graft rubbers according to the invention, the mesh length is in any case greater than 10,000 g / mol, preferably 10,300 g / mol and particularly preferably greater than 10,500 g / mol. The relaxation time T _{2s of} the grafted rubber is then advantageously in the range from 2.4 ms to 10 ms, preferably 2.6 ms to 10 ms and particularly preferably 2.65 to 8 ms. The relaxation time distribution of the grafted rubber is, however, more complicated than that of the ungrafted rubber, since in particular with shorter relaxation times additional immobile fractions appear, which can be assigned, for example, spins to the graft shell. Even after installing the grafted rubber as an impact modifier in a hard material matrix, the characteristic relaxation times of the rubber dispersion according to the invention can be demonstrated. Compared to the grafting stage, increased values are measured, which can almost reach the values of the base rubber. The T _m value in such mixtures is advantageously more than 3.1 ms, preferably more than 3.15 ms and particularly preferably more than 3.2 ms. The mesh length of the base rubber in the hard material matrix is more than 11,500 g / mol, preferably more than 11,750 g / mol and particularly preferably more than 12,000 g / mol. The T _2s relaxation time is preferably in the range from 2.7 to 10 ms, preferably 2.8 to 10 ms and particularly preferably 2.9 to 10 ms.

The rubber incorporated into the hard material matrix can be recovered from the matrix as an insoluble fraction by solvent extraction. After removal of the thermoplastic or thermosetting matrix, this insoluble portion shows the length of the net arch and relaxation times which essentially correspond to those of the particulate, partially or fully crosslinked rubber according to the invention. The T _2s value is then advantageously more than 2.9 ms, preferably more than 3.0 ms and particularly preferably more than 3.1 ms.

Particulate, partially crosslinked rubbers which are suitable according to the invention and have the claimed network structure are composed, for example, of the following monomers whose polymers have a T _g below 0 ° C.: -C 1 -C ₈ -alkyl (meth) acrylates, in particular, -C 1 -C ₂ -alkyl (meth) acrylates, siloxanes such as dimethylsiloxane or diphenylsiloxane, C ₂ -C ₃₂ -01efins, di-olefins such as 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-methyl-1,3- butadiene, 2-ethyl-l, 3-butadiene, 1, 3-pentadiene, 2-methyl-l, 3-pentadiene, 1, 3-hexadiene, 2-phenyl-l, 3-butadiene, 3,4- Dimethyl-1,3-hexadiene, 1,3-heptadiene, 1,3-octadiene, 4,5-diethyl-1,3-octadiene, 3-methyl-1,3-pentadiene and 4-methyl-1,3- pentadiene. The monomers can be copolymerized with other monomers whose T _{g is} above 0 ° C., such as, for example, syrene, (meth) acrylonitrile, (meth) acrylic acid and its derivatives. Preferred types of rubber are branched polyethylenes, copolymers of olefins (with one another and with polyolefins), such as, for example, EP and EPDM rubbers, ethene copolymers with C - to Cio-olefins, polybutadienes, polyisoprenes and their copolymers with styrene, acrylonitrile and (meth) acrylates and polysiloxanes. However, particularly preferred are acrylate rubbers which are composed of ai) 50 to 100% by weight of an alkyl acrylate with an alkyl radical of 1 to 30 C atoms and only one C = C bond, and a ₂ ) 0 to 50% by weight of at least one further monomer which can be copolymerized with al)

The rubber according to the invention is advantageously from 80 to 99.9% by weight of component ai) and 0.1 to 20% by weight of component a ₂ ), preferably from 90 to 99.8% by weight of ai) and 0.2 to 10% by weight .% a ₂ ) built up.

Component ax) is particularly preferably selected from n-butyl acrylate and 2-ethylhexyl acrylate.

Component a ₂ ) preferably contains 0.1 to 10% by weight, based on ai) + a ₂ ), of a crosslinking agent. The crosslinker can have, for example, at least two, preferably differently reactive, double bonds. Preferred crosslinking agents are dihydrodicyclopentadienyl acrylate (DCPA, see DP 1 260 135)) and alkyl (meth) acrylate.

In the case of acrylate rubbers, the graft shell preferably consists of styrene, acrylonitrile, an ester of (meth) acrylic acid or a mixture of preferably two or three of these monomers.

The rubber dispersion can be prepared by all known polymerization methods, for example in solution, in dispersion, in suspension, as microsuspension, emulsion, mini-emulsion, etc., radical, anionic, cathionic or coordinative polymerization processes being able to be used. Processes are preferably used which already lead to particle-like polymers, for example emulsion, mini-emulsion, suspension and microsuspension processes. Radical polymerization is particularly preferred.

The resulting polymer dispersion then typically has a solids content of 5 to 80% by volume, preferably 10 to 75 and particularly preferably 15 to 70% by volume. The average particle diameter is in the range from 25 nm to 1 mm, preferably 50 nm to 100 μm and particularly preferably 50 nm to 10 μm.

Typical monomers copolymerizable with ai) include dienes, preferably butadiene, derivatives of (meth) acrylates with an alcohol residue of up to 32 carbon atoms, glycidyl (meth) acrylate, (meth) acrylamide, butadiene, isoprene, styrene, acrylonitrile and crosslinking agents such as DCPA and allyl (meth) acrylate represent particularly preferred comonomers a ₂ ). The particulate rubber-elastic polymer is produced in such a way that the transverse core magnet table relaxation time is in the range specified above. Such a polymer can be obtained, for example, by dispersing components ai) and a ₂ ) in water, if appropriate using an emulsifier. Component a ₂ ) contains up to 50% by weight, preferably 0.1 to 20% by weight and particularly preferably 0.2 to 10% by weight, based on ai) and a ₂ ) of a crosslinker, for example a crosslinker with at least one two, preferably differently reactive double bonds. The dispersion is then polymerized with a radical polymerization initiator at a temperature in the range from 0 to 150 ° C., preferably 20 to 80 ° C. and particularly preferably about 20 to 60 ° C.

With this method, by combining a crosslinker with at least two, preferably differently reactive, double bonds, such as DCPA or allyl (meth) acrylate, a network with a relatively long network arc length is obtained, which leads to T ₂ relaxation times in the claimed range. Since the polymerization is carried out at a comparatively low temperature, chain extension is preferably carried out on the more reactive double bond, while crosslinking takes place less frequently on the less reactive double bond.

The polymer according to the invention can be used grafted or ungrafted as an impact modifier. When used as a graft copolymer, the graft shell is preferably constructed from the same monomers from which the hard matrix to be modified is made. The alkyl acrylate rubber is preferably grafted with styrene-acrylonitrile (SAN, methyl methacrylate (MMA) or SAN-MMA) as a graft base for modifying a styrene-acrylonitrile copolymer (PSAN matrix) (likewise a Pa-methylstyrene-AN matrix, a Poly-butylene-glycol terephthalate (PBT matrix) or a matrix of polycarbonate (PC), of poly-oxymethylene (POM), of polyvinyl chloride (PVC), polyethylene-glycol terephthalate (PET) and polyethylene naphthalate ( PEN), or polymethyl methacrylate (PMMA) In addition to MMA, acrylates or reactive groups such as carboxalic acid, maleic acid and their anhydrides are preferably used for the impact modification of polyamide. In addition to SAN and SAN-MMA, reactive groups are also used for the modification of thermoplastic urethane (TPU) To modify a polyphenyl ether matrix (PPE), polystyrene (PS) is preferably used as the graft shell, and the rubber dispersion can be used to modify a poly (ether) sulfone matrix on ungrafted or grafted with SAN. Styrene is preferably used as a graft shell to modify a syndiotactic polystyrene (SPS) matrix. A thermosetting matrix, such as epoxy resin, can be modified by the ungrafted or SAN-grafted rubber dispersion. For modification styrene / polyester duromers are preferably modified by an ungrafted or PS grafted rubber dispersion.

The particulate rubber-elastic polymer according to the invention can also be used in blends such as, for example, ASA / PC, PBT / ASA, PA / ASA, PVC / ASA, ASA / TPU, PPE / PA-ASA, PET / ASA, PEN / ASA, PP-ASA, PE-ASA, PC-P-Ester-ASA, PC-TPU-ASA.

Butyl acrylate rubbers according to the invention have a mesh length between 11,500 and 50,000, preferably between 13,000 and 40,000 and particularly preferably between 14,000 and 30,000 g / mol. At a sample temperature of 140 ° C, transverse relaxation times T _2m of 3.2 to 15 ms are found. When determining the relaxation time distribution, at least 70% of a fast fraction with an average transverse relaxation time T _{2s is} in the range from 2.7 to 10 ms, preferably from 2.8 to 10 ms and in particular from 3.0 to 8 ms.

The knowledge on which the present invention is based can also be used in production and quality control. In any production stage, ie after the rubber has been produced, after the rubber has been grafted or after the molding compound has been produced, a sample can be examined and the relaxation times or the distribution of the relaxation times described above can be checked. The invention thus also relates to a process for the quality control of particulate, partially crosslinked rubbers, a sample of the particulate, partially crosslinked rubber or a graft copolymer prepared on the basis of the rubber or a molding composition containing the rubber or graft copolymer being obtained and by means of a nuclear magnetic resonance method Relaxation time distribution h (T ₂ ) or h (2nT)) of the transverse magnetization was determined.

The invention is explained in more detail below by examples.

Production of the Particulate Rubber-Elastic Polymer:

Unless otherwise stated, the following chemicals were used: Deionized water saturated with nitrogen;

Emulsifier: the sodium salt of the C ₂ -C paraffin sulfonic acid in 40% aqueous solution (emulsifier K30 from Bayer); n-butyl acrylate (BA): after distillation in a rotary evaporator;

Crosslinker: DCPA;

Catalyst: Disolvine E-Fe 13 from Akzonobel (this is a 0.1% aqueous solution of an iron salt of ethylenediaminetetraacetic acid (EDTA iron III sodium salt). Styrene and acrylonitrile were obtained from BASF AG and without further purification used.

Production of the seed latex:

3,353 g of deionized water, 55.5 g of emulsifier K 30 as a 40% aqueous solution, 6.7 g of potassium persulfate and 8.6 g of NaHC0 ₃ were placed in a round glass flask. The reaction mixture was heated to 60 ° C under nitrogen. 217.6 g butyl acrylate and 'g DCPA were added quickly. Another 1,958.4 g butyl acrylate and 39.6 g DCPA were added over the following three and a half hours. The post-reaction time was 2 hours. The solids content of the latex thus obtained was 39.8%.

Determination of notched impact strength:

The notched impact strength was determined in accordance with ISO 179 using a Jzod test specimen measuring 4 mm × 10 mm × 79.2 mm. For this purpose, the graft copolymer prepared in Examples 1 and 2 and Comparative Examples 3 and 4 was incorporated into a matrix of a copolymer consisting of 67% by weight of styrene and 33% by weight of acrylonitrile, a 0.5% solution of the copolymer in dimethylformamide being one Has a viscosity of 80 ml / g (measured at 23 ° C; DIN 53726). For this, 41.7% % of the graft copolymer in 58.3% by weight of the copolymer in an extruder (ZSK 30, Werner & Pfleiderer) and extruded at 270 ° C into a mold at 50 ° C. The molding compound had a melt volume index of more than 30 ml / 10 min. (Measured according to ISO 1133 B with a granulate of the molding compound at 220 ° C. and a load of 2.16 kg).

Determination of the relaxation time distribution (NMR measurements)

The dispersions were poured out in a layer thickness of approximately 1 mm and the water of the dispersions was vented for 12 hours at 23.degree. Approximately 500 mg dried The basic or grafting stage was introduced into a measuring tube (filling height 10 mm), the free volume was flushed with gaseous nitrogen and the measuring tube was melted off. The T ₂ measurements were carried out at a sample temperature of 140 ° C. in an NMR analyzer (model MQ20 from Bruker). Measurement and evaluation methods for T ₂ determination are known to the person skilled in the art. In the examples, a method was used that is described in Andreis et al., AdvPol. Sci. 69. (1989), 89.

To determine the relaxation time distribution of the "insoluble" gel portion of the molding composition, 10 g of the molding composition is added to 160 ml of methyl ethyl ketone at 23 ° C. and left to stand for 24 hours. Then centrifuge for 1.5 hours at 14,000 revolutions per minute and then decant. This process is repeated two more times. Thereafter, the "insoluble" portion obtained is dried for 16 hours at 60 ° C. in vacuo at a pressure of 1 torr. The relaxation time distribution is then determined.

example 1

To prepare the basic rubber stage, 1,310 g of deionized water, 23.7 g of emulsifier K 30 (40% aqueous solution) (1% based on monomers), 929.0 g of butyl acrylate and 19.0 g of DCPA were added to a glass reactor and heated to 40 ° C under nitrogen. Over a period of 2 hours, 120.0 g of water and 5.7 g of potassium persulfate were added to the reaction mixture, the temperature of which was kept at 40 ° C. The post-reaction time was 9 hours. A sample of the dispersion thus obtained was taken and analyzed. The solids content of the sample was 38.2%. The T ₂ relaxation time distribution and the mesh length of the rubber are summarized in Table 1 (row IG).

To prepare the graft stage, 2,195.0 g of water were first added and the reaction mixture was heated to 60.degree. After adding 2.4 g of potassium persulfate, 457.3 g of styrene and 152.4 g of acrylonitrile were run in over the course of 130 minutes. Polymerization was carried out at a temperature of 60 ° C. for a further 2 hours. After the reaction had ended, a sample of the grafting stage was taken and analyzed (Table 1: 1P). The solids content of the sample was 29.5%. The average particle size was 170 nm.

A molding composition as described above was produced and analyzed accordingly (Table 1: 1B). The notched impact strength of the molding composition (measured at 23 ° C.) was 51.5 kJ / m ² . subse- The insoluble gel fraction was extracted from the molding composition as described above and also analyzed (Table 1: 1U).

Example 2

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1,055.0 g of deionized water were placed in a glass reactor. 12.7 g of seed latex, 3.8 g of NaHC0 ₃ and 4.0 g of disolvine solution were added and the mixture was brought to 40 ° C. under nitrogen

10 warms. The following was run in within 5 hours:

1) 1000 g butyl acrylate and 20.4 g DCPA;

2) 243.0 g deionized water, 4.5 g ascorbic acid and 15.3 g 40% K30 solution;

3) 243.0 g deionized water and 15.0 g 30% hydrogen peroxide solution in water.

The polymerization was continued for 100 minutes with stirring. The solids content of the basic stage thus obtained was 38.7% (measurement results in Table 1: 2G).

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To prepare the grafting step, 1578.9 g of deionized water and 4.7 g of the 40% K30 solution of the dispersion were added and the mixture was then heated to 60.degree. Then 1.8 g of potassium persulfate are added. 221 g of styrene are added within 60 minutes. After a post-reaction time

25 of 60 minutes, a mixture of 344.3 g of styrene and 114.7 g of acrylonitrile was run in within 2 hours. The mixture was then polymerized for 3 hours. The solids content of the grafting stage thus obtained was 34.1% and the average particle size was 150 nm (analysis results in Table 1: 2P).

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We produced and analyzed the molding compound and the insoluble fraction of the molding compound (results in Table 1: 2B and 2U). The notched impact strength of the molding compound thus obtained (measured at 23 ° C.) was 49.3 kJ / m ^2nd

Example 3 (comparative example)

₄₀ 4,140.4 g deionized water and 51.9 g seed latex were placed in a glass reactor and heated to 65 ° C. under nitrogen. 9.3 g of potassium persulfate and 11.9 g of NaHC0 ₃ were added. The following mixtures were allowed to run into the reactor:

1) 3031.0 g butyl acrylate and 61.9 g DCPA; 45 2) 518.0 g water and 46.3 g 40% K30 solution.

10% of the mixture 1) were added within 20 seconds and the rest within 5 hours. Mixture 2) was left run in within 5.5 hours. The temperature of the reaction mixture was kept at 65 ° C. Polymerization was then continued for 135 minutes and a sample of the basic rubber stage thus obtained was taken. The solids content of the sample was 39.2%. (Table 1: 3G).

To prepare the graft stage, the basic stage dispersion was filtered (mesh size: 500 μm). 3765 g of the dispersion, 1467 g of water and 12.8 g of emulsifier K30 (40% strength aqueous solution) were placed in a round glass flask and heated to 65.degree. Then 3.9 g of potassium persulfate were added. The dispersion was grafted in a two-step process. 320.6 g of styrene were added within 90 minutes. This was followed by a post-reaction time of 1 hour. Then 499.4 g of styrene and 166.5 g of acrylonitrile were added within 90 minutes. The mixture was allowed to polymerize further for two hours. The solids content of the graft stage thus obtained was 39.1%. The mean particle size was 580 nm. The results are summarized in Table 1 (3P). The molding compound and the insoluble fraction of the molding compound were analyzed in accordance with Example 1 (3B and 3U). The notched impact strength of the molding compound produced in this way (measured at 23 ° C.) was only 13.2 kJ / m.

Example 4 (comparative example)

2966 g of deionized water and 28.5 g of seed latex were placed in a round glass flask and heated to 60 ° C. under nitrogen. Then 6.6 g of potassium persulfate and 8.5 g of NaHC0 _{3 were} added. A mixture of 2165 g of butyl acrylate and 44.2 g of DCPA was run in within 3.5 hours and a mixture of 370 g of water and 33.1 g of K30 solution in the course of 4 hours. The post-polymerization time was 2 hours. The base rubber thus obtained had a solids content of 38.9% (Table 1: 4G).

To graft the rubber, 2229 g deionized water, 19.3 g K30 solution and 5.9 g potassium persulfate were added to the basic stage at 60 ° C. 481 g of styrene were run in within one hour. This was followed by a post-polymerization time of 1 hour. A mixture of 749 g of styrene and 250 g of acrylonitrile was then allowed to run in over the course of 2 hours, and the reaction mixture was then polymerized further for 2 hours. The grafting stage thus obtained had a solids content of 39.1% and an average particle size of 500 nm (measurement results in Table 1: 4P). The molding composition and the insoluble fraction of the extracted molding composition were analyzed in accordance with Example 1 (Table 1: 4B and 4U, respectively). The notched impact strength of the molding composition thus obtained (measured at 23 ° C.) was only 18.5 kJ / m ² .

table

Claims

claims

1. Particulate, partially or fully crosslinked rubber with a glass transition temperature which is lower than 0 ° C., the rubber having crosslinking points which are connected to one another by network sheets which have an average molecular weight between 10,000 g / mol and 50,000 g / mol.

2. Rubber according to claim 1, characterized in that the average molecular weight of the mesh sheets is between 13,000 g / mol and 40,000 g / mol, preferably between 14,000 g / mol and 30,000 g / mol.

3. Particulate, partially crosslinked rubber with a glass transition temperature which is lower than 0 ° C., characterized in that a relaxation of a transverse magnetization of ⁱ H-nuclei of the rubber can be described by a transversal relaxation time (T _2m ) which is in the range from 3 to 15 ms when measuring at a temperature of 140 ° C.

4. Rubber according to claim 3, characterized in that the relaxation of the transverse magnetization can be described by an at least bimodal relaxation time distribution (h (T ₂ )), a first fraction, the proportion of which is at least 70%, an average transverse relaxation time (T _2s ) in the range from 2 to 10 ms, preferably from 2.8 to 10 ms and particularly preferably from 3.0 to 8 ms.

5. Rubber according to claim 4, wherein a second fraction, the proportion of which is at most 30%, has an average transverse relaxation time (T _2f ) of more than 10 ms.

6. Rubber according to one of claims 3 to 5, characterized in that the polymer between adjacent crosslinking points has mesh arches whose average molecular weight is more than 10000 g / mol, preferably more than 13000 g / mol and particularly preferably more than 14000 g / mol ,

7. Rubber according to one of claims 1 to 6, characterized in that the rubber is composed of ai) 50 to 100 wt.% At least one alkyl acrylate with an alkyl radical of 1 to 30 carbon atoms and only one C = C bond, and a ₂ ) 0 to 50% by weight of at least one further monomer which can be copolymerized with ai).

8. Rubber according to claim 7, composed of 80 to 99.9% by weight of component ai) and 0.1 to 20% by weight of component a ₂ ), preferably 90 to 99.8% by weight of a ^ and 0.2 to 10% by weight of a ₂ ).

9. Rubber according to one of claims 7 or 8, characterized in that component ai) is selected from n-butyl acrylate and 2-ethylhexyl acrylate.

10. Rubber according to one of claims 7 to 9, wherein component a ₂ ) contains 0.1 to 10 wt.% Based on aχ) + a ₂ ) of a crosslinking agent.

11. A process for producing the rubber according to any one of claims 7 to 10 in water, wherein ai) 50 to 100 wt.% Of an alkyl acrylate with an alkyl radical of 1 to 30 carbon atoms and only one C = C bond, and a) 0 up to 50% by weight of at least one further monomer which can be copolymerized with ai) and contains at least 0 to 10% by weight, based on aχ) + a ₂ ), of a crosslinking agent, if appropriate using a surface-active agent with a radical polymerization initiator at one temperature in the range from 30 to 50 ° C, preferably 35 to 45 ° C and particularly preferably from about 40 ° C.

12. The method according to claim 11, characterized in that the crosslinked DCPA or allyl (meth) acrylate is used.

13. The method according to any one of claims 11 or 12, characterized in that component ai) is selected from n-butyl acrylate and 2-ethylheyl acrylate.

14. Graft copolymer, produced by grafting 0.1 to 99.9% by weight, preferably 5 to 95% by weight and particularly preferably 10 to 90% by weight of a graft base consisting of the rubber according to one of claims 7 to 10 with 0 , 1 to 99.9% by weight, preferably 5 to 95% by weight and particularly preferably 10 to 90% by weight of a graft shell.

15. Graft copolymer according to claim 14, wherein the graft shell contains styrene, acrylonitrile, an ester of (meth) acrylic acid or a mixture of these monomers.

16. Use of the rubber according to one of claims 1 to 10 or of the graft copolymer according to one of claims 14 or 15 to increase the notched impact strength of thermoplastic or thermosetting molding compositions.

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17. Thermoplastic or thermosetting molding composition containing 1 to 99 parts by weight, preferably 5 to 95 parts by weight and particularly preferably 10 to 90 parts by weight of a thermoplastic or thermosetting polymer as a matrix, 1 to 99

10 parts by weight, preferably 5 to 95 parts by weight and particularly preferably 10 to 90 parts by weight of the rubber according to one of claims 7 to 10 and / or a graft copolymer according to one of claims 14 or 15, and up to 50 Parts by weight of conventional additives, the iso- from the molding compound

15 insoluble portion has a transverse relaxation time (T _2m ) which is in the range from 3 to 10 ms when measured at a temperature of 140 ° C.

18. Molding composition according to claim 17, characterized in that the 20 relaxation of the transverse magnetization of the rubber can be described by a bimodal relaxation time distribution h (T ₂ ), a first fraction, the proportion of which is at least 85%, an average transverse relaxation time (T _2s ) in the range from 2 to 10 ms, preferably from 2.8 to 25 10 ms and particularly preferably from 3.0 to 8 ms.

19. Moldings from molding compositions according to one of claims 17 or 18.

30 20. Method for quality control of particulate, partially crosslinked rubbers, characterized in that a sample of the particulate, partially crosslinked rubber or a graft copolymer prepared on the basis of the rubber or one of the rubber or the graft copolymer

35 molding compound containing lymerisate is obtained and the relaxation time distribution h (T ₂ ) of the transverse magnetization is determined by means of a nuclear magnetic resonance method.

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