CA2266467A1 - New polymer compositions, graft copolymers and thermoplastic compounds with cross-linking gradients made of such compositions - Google Patents

Abstract

A hard segment H1 is disclosed with a glass transition temperature of at least 10 ~C which contains at least one polymerised vinyl aromatic monomer as monomer or one among two or several monomers that can be copolymerised together, at least one cross-linking agent with two or more functional groups of different reactivities and at least one cross-linking agent with two or more functional groups of the same reactivity. The concentration of at least one cross-linking agent varies in the hard segment. A process for producing these segments is also disclosed, as well as graft copolymers which contain these segments, a process for producing these graft copolymers and thermoplastic compounds containing these graft copolymers, moulded bodies, foils, fibres and coatings which contain at least one of the disclosed segments, graft copolymers and thermoplastic compounds.

Description

NEW POLYMER COMPOSITIONS, GRAFT COPOLYMERS AND
THERMOPLASTIC COMPOUNDS WITH CROSS-LINKING
GRADIENTS MADE OF SUCH COMPOSITIONS

The present invention relates to a hard segment Hl having a glass transition temperature of at least 10~C, contain-ing, as polymerized units, at least one vinylaromatic monomer as the monomer or as one of two or more monomers copolymerizable with one another and at least one cross-linker having two or more functional groups of different reactivity and at least one crosslinker ha~ing two or more functional groups of the same reactivity, the concentration of at least one crosslinker in the hard segment varying.

The present invention furthermore ~elates to a process for the preparation of these segments and graft copoly-mers which contain these segments, processes for the preparation of these graft copolymers and thermoplastic materials which contain these graft copolymers. The present invention also relates to moldings, films, fibers . and coatings which contain or use at least one of the novel segments, graft copolymers and thermoplastic materials.

Graft copolymers, which are frequently referred to as core-shell particles, are known, for example, as impact modifiers for plastics such as gtyrene/acrylonitrile copolymers, polyvinyl chloride (PVC), polymethyl meth-acrylate or polycarbonate. They may be composed of two or more stages-CA 02266467 l999-03-24 ' - 2 -The grafting base, the core, may consist of an elasto-meric soft segment, ie. one having a glass transition temperature of less than about 24~C, for example less than 0~C, or a nonelastomeric, hard segment, ie. one having a glass transition temperature of more than about 25~C, for example more than 50~C. The graft layer or shell may accordingly be hard or soft or, in the case of multistage graft copolymers, may be alternately hard and ~oft or soft and hard.

The glass transition temperature of the individual stage~
may be influenced in each case by the choice of the mon~m~rs and furthermore by the addition of one or more crosslinkers. For example, mono~rs which have two or more functional groups capable of reacting with the monomers forming the grafting base or graft layer have a crosslinking action. If all functional groups of the polyfunctional monomers react at the same rate, these ~onomers have only a crosslinking effect. However, if the crosslinkers contain functional groups of different reactivity, the functional groups which have not reacted can serve as grafting points, for example for bonding a graft layer to the grafting base. Such crosslinkers thus have not only a crossl; nk; ng action but also a gra$t-linking effect.

The purposes for which graft copolymers can be used, for example the way in which they influence optical quality, colorability, stability to weathering or impact cracking and stress crack corrosion in molding materials, depend on their composition as well as on their size and morphology.

It has not been possible to date to prepare graft copoly-mers (for example those composed of a polystyrene core, a first shell of polybutyl acrylate and a second shell of styrene/acrylonitrile copolymer) which have a large particle size and a genuine core-8hell structure if core and shell materials were incompatible with one another (cf. for example H. Okubo, Makromol. Chem., Macromol.
Symp. 35/36 (1990), 307-325). Above certain particle diameters of the grafting base (from about 100 to 150 nm and o~erall particle sizes from about 200 nm), it is in fact found that the grafting base and graft layer form no defined core-shell structure in such graft copolymers.
The core is not surrounded completely and essentially concentrically by the graft layer. The grafting base and graft layer are partially mixed or part of the core material forms the outer phase boundary of the core-ehell particle. This gi~es rise to a raspberry-like morphol-ogy. Also disclosed therein is a copolymer comprising a soft segment and a hard segment, ie. polybutyl acrylate and polystyrene, respecti~ely, wherein the soft segment is present as a matrix and the hard segment as ~omA; n~
without a defined core-shell morphology being formed.

The graft copolymers known to date which have a defined core-shell structure and whose core and shell materials are incompatible with one another therefore ha~e only a small core diameter or a core diameter which is only small in relation to the total size of the graft copoly-mers or they contain a grafting base comprising material which is compatible with the graft layer.

The compatibility of two polymer components is understood a8 meAn; ng in general the miscibility of the components or the tendency of one polymer to dissol~e in the other polymer component (cf. B. Vollmert, Grundri~ der makro-molekularen Chemie, Volume IV, page 22 et seq., E.
Vollmert-Verlag 1~79). ~wo polymers are all the more compatible the smaller the difference between their solubiIity parameters. Such parameters and the enthalpy pf m; Y; ng cannot be determined in a ~tAn~Ard way for all polymers 80 that the solubility can be determined only .. . .

. CA 02266467 1999-03-24 indirectly, for example by torsional ~ibration or differ-ential therm~l analysis (DTA) measurements.

Examples of polymers which are miscible, ie. compatible, with one another are documented in detail in various monographs (for example, J. Brandrup and E.H. Immergut:
Polymer Handbook, 3rd Edition, 1989).

Thus, US-A-4 108 946 disclosed a grafting base which has a particle size of up to 240 nm, comprises crosslinked mo~nm~r mixture~ of styrene/acrylonitrile or styrene/
acrylonitrile/methyl methacrylate and is provided with a graft layer of acrylates. It is stated that pure poly-styrene is undesirable as the grafting base.

DE-A-33 00 526 disclosed graft copolymers which are each composed of a nonresilient core having diameters of up to 500 nm, preferably up to 200 nm, and a crosslinked acrylate shell. Preferably, methyl methacrylate is pre~m;n~ntly used for the monomer material of the core.

US-A-3 793 402 likewise disclosed graft copolymers whose grafting bases are crosslinked. Polyvinylbenzenes, such as divinyl- or trivinylbenzene, are described as cross-linkers for grafting bases which preferably consist of styrene or substituted styrenes, but the novel, advanta-geous crosslinker combinations are not used.

In addition, DE-A-22 44 519 disclosed graft copolymers which each contain a grafting base based on vinylaromatic compounds and up to 10% by weight of crosslinking mono-mers. Furthermore, DE-A-41 32 497 describes graft copolymer~ whose gxafting base~ are col~osed predominant-ly of vinylaromatic monomers and which may contain crosslinkers having a crosslinking as well as graft-~1; nk; ng action. Either graft copolymers which contain small cores (up to about 150 nm) or those which have no .... . . . . . .

. CA 02266467 1999-03-24 defined core-shell morphology can be obtained by the process described there.

In order to obtain impact-resistant, thermoplastic materials, graft rubber6 are added to the polymers which are brittle at room temperature and form the matrix. The preparation of such impact modifiers has long been known and is described, for example, in DE-A-12 60 135, DE-A-23 11 129 and DE-A-28 26 925. If the matrix consists of polystyrene or styrene copolymers, it is possible to observe that the efficiency of the graft copolymers with respect to their impact-modifying effect increases with increasing size of the graft copolymers. When small-particled graft rubbers are used, there is simultaneously the problem that the toughness of the impact-modifying material depends to a great extent on the processing temperature.

Materials having improved impact strength in combination with good colorability can be obtained by m;Y;ng a large-particled rubber component with a small-particled one (bimodal rubber particles), as described in DE-A-28 26 925. The impact strength, in particular the low-temperature impact strength, of the materials which is achieved there is often insufficient for high stress. In addition, the impact strength cannot be increased by ~1; ng any desired amounts of the large-particled rubber since otherwise the colorability deteriorates substantially.

It is an object of the present invention to provide plastics, in particular thermoplastic materials, which, 3C e~pecially at low temperature~, for example be ow O"C, preferably independently of the processing temperature, have better impact strength and stress crack corrosion and in particular better multiaxial toughness and can be more readily colored and have surfaces which are more resistant, and whose surface characteristics, in particu-lar gloss and dullness, can be readily adjusted.

In this context, it is a further object of the invention to provide graft copolymers in which the particle size and a defined phase transition can be established, the establishment of small particles (~ 200 nm) and large particles (2 200 nm) with defined phase transitions being particularly important and large particles being particu-larly preferred.

It is a further object of the present invention to provide products which are resistant to weathering and are based on acrylonitrile/styrene/acrylate (ASA3 polymers, in particular those having a polystyrene-co-acrylonitrile matrix, which, in addition to the advanta-geous properties of the known materials, such as resis-tance to weathering and to aging, have very good tough-ness in combination with good colorability and indepen-dence of the toughness of the processing temperatures.

We have found that these objects are achieved, surpris-ingly, by the hard segment defined at the outset and by the novel graft copolymers and thermoplastic materials.

The hard segments are denoted by H. The nl~her following H numbers the hard segments consecutively. The numbering following this number denotes the monomers or cross-linkers or crosslinker components which are used in thehard segment. The graft copolymers are denoted by P. P
numbers the graft copolymers consecutively. If an ' follows this number, the graft copolymer has a soft 3eg~.9rlc a~3 the gra~ting base; if ~ follow~ the number, the graft copolymer denoted in this way has a hard segment as the grafting base. The following number consecutively numbers the segments which contain the graft copolymer. In preferred novel graft copolymers in which the order of the successive segments i8 not r~n~r~m but fixed, the n~her 1 denotes the grafting base and the numbers 2, 3, etc. denote in se~uence the graft layers following the grafting base. The third number following P denotes the monomers, crosslinkers or crosslinker components contained by the segment. T denotes the novel thermoplastic materials. The number following T consecu-tively numbers the thermoplastic materials. The Roman numerals written in lower case letters denote the com-ponents contained by the materials.

The no~el hard segment Hl preferably has one or more ofthe following features:
a) that the concentration of at least one crosslinker having two or more functional groups of different reactivity, preferably dihydrodicyclopentadienyl acrylate, ~aries, but preferably increases, from the inside to the outside of the hard segment H1;
b) has a glass transition temperature of at least 25~C;
c) contains at least H1.1) from 50 go 99.8% by weight of at least one vinylaromatic ~onnmer, Hl.2) from 0 to 49.8% by weight of at least one monomer copolymerizable with monomer Hl.l, Hl.3) from 0.1 to 25% by weight of a crosslinker component comprising ~) from 0.1 to 100% by weight of dihydro-dicyclopentadienyl acrylate and ~) from 0 to 99.9% by weight of at least one further crosslinker ha~ing two or more functional group~ of different reactivity, the ~um of the percentages by weight of ~ and ~ being 100, and H1.4) from 0.1 to 25% by weight of at least one ~ crosslinker having two or more functional groups of the same reactivity, the sum of the percentages by weight of Hl.l to H1.4 being 100 .

The novel hard segments Hl having a glass transition temperature of at least 10~C, preferably at least 25~C, contain at least one vinylaromatic ~o~omer as the monomer or as one of two or more ~onom~rs copolymerizable with one another and at least one crosslinker having two or more functional groups of different reactivity and at least one crosslinker having two or more functional groups of the same reactivity, the concentration of at least one crosslinker in the hard segment H1 varying. In a particularly preferred embodiment of the novel hard segment H1, preferably the concentration of the cross-linker having functional groups of different reactivity varies. In a further novel embodiment of the hard segment Hl, however, preferably the croeslinker having two or more functional groups of the same reactivity varies. However, it may also be preferable if both the concentration of the crosslinker having functional groups of different reactivity and the concentration of the crosslinker having functional groups of the same reacti-vity vary in the novel hard segment Hl.

Furthermore, it is particularly preferred according to the invention that the concentration of at least one crosslinker having two or more functional groups of different reactivity increases from the inside to the outside of the hard segment. This is preferably accom-panied by a decrease in the concentration of at least one crosslinker having two or more functional groups of the same reactivity from the inside to the outside of the har~1 ~egment }I1.

The hard segment H1 has an essentially spherical shape, particularly when it is used in a graft copolymer and preferably when it is used as the grafting base. When - .. CA 02266467 1999-03-24 the hard segment Hl is used as the graft layer, it preferably has an essentially shell-like shape. However, it may also be preferable according to the invention if the novel hard segment Hl has essentially the form of a layer.

If the novel hard segment Hl is used as an essentially spherical grafting base, it is preferable if the concen-tration of at least one crosslinker having two or more functional groups of different reactivity increases from the inside to the outside of the essentially spherical hard segment.

If the novel hard segment Hl is used as an essentially layer-like or preferably shell-like graft layer, it is preferable if the concentration of at least one cross-linker having two or more functional groups of differentreactivity increases from the inner to the outer surface of the essentially shell-like or layer-like hard segment.

According to the invention, the added amount over the period of at least one crosslinker having two or more functional groups of different reactivity may be varied and the added amount of at least one crosslinker having two or more functional groups of the same reactivity may remain constant over the time of addition, if such a crosslinker is used.

According to the invention, it may be preferable if the decrease and/or the increase is monotonic, preferably strictly monotonic. Preferably, the increase and/or decrease is linear, preferably exponential. According to ~ha invention, it may also be preferable ir the increa~e or decrease is stepwise, for example in the form of a staircase or in the form of a sawtooth pattern or in the form of a term having one or more irregularities or in the form of a sinusoidal wave function. According to the ' CA 02266467 1999-03-24 invention, it may furthermore be particularly preferable if two or more of the abovementioned forms of the in-crease or decrease are combined with one another.

The manner in which the crosslinkers are present in the S novel hard segment H1 preferably depends on the method of metering the crosslinkers. For example, monotonically, preferably strictly monotonically, increasing crosslinker addition results in a hard segment in which the concen-tration of the correspo~;ng crosslinker, preferably having two or more functional groups of different reac-tivity, likewise increases monotonically, preferably strictly monotonically, from the inside to the outside.

The novel hard segments Hl preferably have a glass transition temperature of at least 10~C, preferably at least 25~C, particularly preferably at least 50~C, it being particularly preferred according to the in~ention if the hard segments have a glass transition temperature of from 80 to 130~C.

The novel hard segments Hl may have a mean particle size (d50) of from 40 to 2000 nm, preferably from 50 to 1000 nm, particularly preferably from 60 to 800 nm, if the hard segment Hl is used as the essentially spherical or core-like grafting base. In a particularly preferred embodiment in which the hard segment H1 is used as the essentially core-like grafting base, said hard segment has a mean particle size (d50) of from 150 to 2000 nm, in particular from 250 to 1000 nm, particularly preferably from 250 to 800 nm. In another novel embodiment, the hard segment H1 has a mean particle size (d50) of from 40 to 20C n~, preferab y from 50 to 150 nm, particillarly preferably from 60 to 120 nm, if it is used as the essentially core-like grafting base.

The stated mean particle size is in all cases the weight , . . ~

. ~ CA 02266467 1999-03-24 average of the particle size, as determined by means of an analytical ultracentrifuge according to the method of E. Scholtan and H. Lange, ~olloid-Z. und Z.-Polymere 250 (1972), 782-796. The ultracentrifuge measurements give the integral mass distribution of the particle diameter of a sample. From this it is possible to determine the percentage by weight of particles which have a diameter equal to or less than a certain size. The mean particle diameter, which is also referred to as the d50 value of the integral mass distribution, is defined as the par-ticle diameter at which 50% by weight of the particles have a smaller diameter than the diameter which corres-ponds to the d50 value. Furthermore, 50% by weight of the particles have a larger diameter than the d50 value.

A hard segment H1 preferred according to the invention contains H1.1) from 50 to 99.8% by weight of at least one aroma-tic monomer, H1.2) from 0 to 49.8% by weight of at least one mo~omer copolymerizable with the monomer H1.1, H1.3) from 0.1 to 25% by weight of a crosslinker com-ponent comprising ~) from 0.1 to 100% by weight of dihydrodicyclo-pentadienyl acrylate and ~) from 0 to 99.9% by weight of at least one further crosslinker having two or more func-tional groups of different reactivity, the sum of the percentages by weight of ~ and being 100, and Hl.4) from 0.1 to 25% by weight of at least one cross-linker having two or more functional groups of the same reactivity, where the crossiinlers stated under Hl.3 or Hl.4 may be varied in their concentration in the manner described above.
, 35 The novel hard segments Hl are preferably used for graft ~ ~ CA 02266467 l999-03-24 copolymers.

Preferred among these graft copolymers is the novel graft copolymer P1 which contains, in any desired sequence, at least one soft segment, having a glass transition tem-- perature of not more than 10~C and cont~in;ng at least one acrylate as a mo~omer or as one of two or more mo~n~ers copolymerizable with one another and at leaQt one crosslinking agent, and one hard segment H1, as described above.

The following ~tatements apply to novel hard Qegments in general and in particular to the hard segment H1, and vice versa.

A preferred embs~iment of the graft copolymer P1 is the graft copolymer P1'. This contains the soft segment as grafting base Pl'.1 and the hard segment H1 as graft layer P1'.2, the concentration of at least one cross-linker in the soft segment preferably being varied.

A particularly preferred embodiment of the graft copoly-mer P1 i8 the graft copolymer P1'', which contains the hard segment H1 as grafting base P1''.1 and the soft segment as graft layer P1''.2.

A further embodiment preferred according to the invention is the graft copolymer P2. In one embodiment, this contains the graft copolymer P1 with any sequence of the ~oft segment and of the hard segment.

In a particularly preferred embodiment of the graft copo~ymer P2, ~he graf~ cop~ly~.er P2' prefeiably contain~
the soft segment P1'.1 a~ grafting base P2~1. and the hard segment P1'.2 as graft layer P2'.2.
'! , In a further preferred embodiment of the graft copolymer '. CA 02266467 1999-03-24 P2, the graft copolymer P2'' preferably contains the hard segment P1''.1 as grafting base P2''.1 and the soft segment Pl''.2 as graft layer P2''. 2.

In addition, the novel graft copolymers P2, P2' and P2'' contain a further graft layer in the form of a soft segment having a glass transition temperature of not more than 10~C and cont~ining at least one acrylate as a mo~om~r or as one of two or more mo~o~ers copolymerizable with one another and at least one crosslinker (P2. 3, P2' .3 and P2''.3).

A graft copolymer P2' having a soft segment P2'1., which corresponds to the soft segment Pl'.1, and a hard segment P2'.2, which corresponds to the hard segment Pl'.2 or H1, and a further soft segment P2'3 described above is particularly preferred according to the invention.

The following statements relating to the novel graft copolymers P1 and P2 also apply in particular to their preferred embodiments Pl' or P1'' and P2' or P2''.

In the novel graft copolymers P1 or P2, it is preferable for the concentration of at least one crosslinker to be varied at least in the hard segments, as explained above in the description of the hard segment H1. According to the invention, however, it may also be preferable if the concentration of at least one crosslinker varies in the other segments of the novel graft copolymers P1 and P2 in addition to the hard segment.

Where the soft segments present in the novel graft copolymer~ P1 or P2 con'ain at least one cro~linker and two or more functional groups of different reactivity and at least one crosslinker having two or more functional qroups of the same reactivity, the concentration of one or more of these crosslinkers may vary, as stated for the ~ CA 02266467 l999-03-24 hard segment H1.

Accordingly, it may be preferable if, in the case of the graft copolymer Pl, both at least one crosslinker of the soft segment and at least one crosslinker of the hard segment vary in their concentration. In the case of the graft polymer P2, both at least one crosslinker in a soft segment and in the hard segment may vary and at least one crosslinker in both soft segments and in the hard segment may vary.

Furthermore, it is particularly preferable if, in the case of the graft copolymers P1' or P2', the concentra-tion of at least one crosslinker i~ varied both in the soft segment forming the grafting base and in the hard segment forming the subsequent graft layer, it being possible for the concentrations of different crosslinkers to be varied in the soft segment and in the hard segment.
Here, it is preferable according to the invention if the concentration of at least one crosslinker having two or more groups of different reactivity, which is identical for the soft segment and for the hard segment, increases.
According to the invention, it is particularly preferable here if this crosslinker is DCPA.

The preferred novel embodiments of the hard segments H1 preferably contain at least one vinylaromatic monomer as the monomer or as one of two or more monomers copolymer-izable with one another and at least dihydrodicyclopenta-dienyl acrylate as a crosslinker having two or more functional groups of different reactivity and at least divinylbenzene as a crosslinker having two or more 3G functional group~ of the ~ame reactivity.

Further particularly preferred embodiments of the novel pard segments H1 preferably contain at least one vinyl-aromatic mo~om~r as the mo~ome~ or as one of a plurality ~ ' CA 02266467 l999-03-24 of monomers copolymerizable with one another and at least dihydrodicyclopentadienyl acrylate as a crosslinker having two or more functional groups of different reac-tivity and at least butanediol diacrylate as a cros~-linker having two or more functional groups of the samereactivity.

Particularly preferred embodiments of the novel hard segments Hl preferably contain at least one vinylaromatic monomer as the monomer or as one of two or more monomers copolymerizable with one another and dihydrodicyclopenta-dienyl acrylate, divinylbenzene and/or butanediol diacrylate.

Hard segments H1 are preferably composed of from 50 to 99.8, especially from 60 to 99, particularly preferably from 60 to 98, % by weight, based on the components H1.1 to H1.4, of at least one vinylaromatic m~omer H1.1.

Novel vinylaromatic m~o~ers preferably having not more than 20 carbon atoms are, for example, styrene, ~-methyl-styrene or styrenes alkylated on the nucleus, such as p-methylstyrene or p-tert-butylstyrene, styrene, ~-methyl-styrene or p-methylstyrene or mixtures thereof being preferably used and styrene being particularly preferably used.

In addition to the monomer H1.1, the novel hard segments H1 may also have, for example, monomers H1.2, preferably nonvinylaromatic ones, which are copolymerizable therewith.

MonGmers H1.2 preferably having not more than 2G carbon atoms are, for example, n-butyl acrylate, acrylonitrile, methacrylonitrile, acrylic acid, methacrylic acid, methyl ~ethacrylate, glycidyl methacrylate, maleic anhydride, tert-butyl acrylate or vinyl methyl ether and mixtures ' CA 02266467 1999-03-24 thereof. Monomers Hl.2 preferred according to the invention are acrylonitrile, a-methylstyrene and methyl methacrylate. The amount of the mo~o~?rs H1.1 i8 from 0 to 49.8, preferably from 0 to 39, particularly preferably from 0 to 38, % by weight, based on the components H1.1 to H1.4.

The hard segments H1 furthermore preferably contain a crosslinker component H1.3 in an amount of from 0.1 to 25, preferably from 0.5 to 10, particularly preferably from 1 to 5, % by weight, based on the component H1.1 to Hl.4.

The crosslinker component may contain dihydrodicyclo-pentadienyl acrylate (~) of the formulae Ia and Ib ~ o C CH--CHl ~) <'~. J

O--C C~H C~H2 ~b) alone or in combination with at least one other cross-linker having functional groups of different reactivity (~) .

According to the invention, the crosslinker component preferably con~i~t~ of from 0.1 to 100, espec.ially ~ron 25 to 100, particularly preferably from 50 to 100, % by weight, based on ~ and ~, of ~ and from 0 to 99.9, ~especially from 0 to 75, particularly preferably from 0 to 50, % by weight, based on ~ and ~, of ~.

- ~ CA 02266467 1999-03-24 Examples of suitable crosslinkers ~ are ethylenically unsaturated mo~ rs which carry epoxy, hydroxyl, carbox-yl, amino or acid anhydride groups. These include hydroxyalkyl acrylates or hydroxyalkyl methacrylates, such as hydroxy-Cl-C10-alkyl acrylates or hydroxy-Cl-C10-alkyl methacrylates, in particular hydroxyethyl acrylate or hydroxy-n-propyl acrylate. Allyl methacrylate, methallyl methacrylate, acryloylalkoxysilanes or meth-acryloylalkyloxysilanes of the general formula II
o H~C==CR2--C~O--(CH2)p--SiRI0(3n)~ (Il) where Rl is Cl-C3-alkyl or phenyl, preferably methyl, R2 is hydrogen or methyl, n is an integer from 0 to 2 and p is an integer from 1 to 6, preferably from 1 to 4, are preferred. Preferred examples are:

~-methacryloyloxyethyldimethoxymethylsilane, r-methacryloyloxy-n-propylmethoxydimethylsilane, ~-methacryloyloxy-n-propylmethoxymethylsilane, ~-methacryloyloxy-n-propyltrimethoxysilane, ~-methacryloyloxy-n-propyldimethoxymethylsilane, ~-methacryloyloxy-n-propyldiethoxymethylsilane and ~-methacryloyloxy-n-butyldiethoxymethylsilane.

The preferred mixtures of the crosslinkers ~ and include dihydrodicyclopentadienyl acrylate and hydroxy-ethyl acrylate; dihydrodicyclopentadienyl acrylate and allyl methacrylate; dihydrodicyclopentadienyl acrylate, hydroxyethyl acrylate and allyl methacrylate; dihydro-dicyclopentadienly acrylate, allyl methacrylate and ~-methacryloyloxyethyldimethoxymethylsilane; dihydro-dicyclopentadisnyl acrylat2 and ~3-methacryloyloxyethyl-dimethoxymethylsilane.

~he novel hard segment H1 preferably has, as H1.4, from 0.1 to 25, especially from 0.5 to 10, particularly ~ CA 02266467 1999-03-24 : - 18 -preferably from 1 to 7, % by weight, based on the com-ponents H1.1 to H1.4, of at least divinylbenzene as a crosslinker ha~ing two or more functional groups of the same reactivity.

A further novel hard segment H1 has from 0.1 to 25, preferably from 0.5 to 10, particularly preferably from 1 to 7, % by weight, based on the components H1.1 to H1.4, of at least butanediol diacrylate as a crosslinker having two or more functional groups of the same reactivity.
.

Examples of suitable crosslinkers H1.4, which may be used in addition to divinylbenzene and/or butanediol di-acrylate but also on their own, are mono-, di-, tri- or tetraalkylene glycol diacrylates, preferably Cl-C4-mono-alkylene glycol diacrylates, such as ethylene glycoldiacrylate, n-propylene glycol diacrylate, 1,3-n-butylene glycol diacrylate or 1,4-n-butylene glycol diacrylate.
Mono-, di-, tri- or tetraalkylene glycol dimethacrylates are also suitable, preferably Cl-C4-monoalkylene glycol dimethacrylates, such as ethylene glycol dimethacrylate, n-propylene glycol dimethacrylate, 1,3-n-butylene glycol dimethacrylate or 1,4-n-butylene glycol dimethacrylate.
Acrylates or methacrylates of glycerol, trimethylol-propane, pentaerythritol, inositol or similar sugar alcohols are also suitable crosslinkers H1.4. Examples of further suitable crosslinkers H1.4 are acrylamides or methacrylamides of ethylenediamine or other aliphatic di-or polyamines. Diallyl maleate, diallyl fumarate or diallyl phthalate, triacrylamides or trimethacrylamides, triallyl cyanurate or triallyl isocyanurate and trivinyl-benzene may also be u-sed as crosslinker Xl,4.

Preferably the hard segments H1 have from 50 to 99.8% by weight of at least one vinylaromatic mo~o~er (H1.1), from 0 to 49.8% by weight of at least one monnmer (H1.2) , ' CA 02266467 1999-03-24 copolymerizable with the monomers Hl.l, from 0.1 to 25%
by weight of a crosslinker component with from 0.1 to 100% by weight of at least one crosslinker having two or more functional groups of different reactivity (Hl.3) and from 0.1 to 25% by weight of divinylbenzene and/or butanediol diacrylate, preferably butanediol diacrylate (Hl.4).

In addition, a preferred novel hard segment Hl has from 0.1 to 25, preferably from 0.5 to 10, particularly preferably from 1 to 7, % by weight, based on the com-ponents Hl.l to Hl.4, of divinylbenzene and/or butanediol diacrylate, preferably butanediol diacrylate.

An additional novel hard segment Hl preferably differs from the preceding hard segments in that the component Hl.3 contains at least (a) from 0.1 to 100% by weight of dihydrodicyclopentadienyl acrylate and (~) from 0 to 99.9% by weight of at lea~t one further crosslinker having two or more functional groups of different reactivity.

In a further novel hard segment Hl, preferably from 0.1 to 100, especially from 25 to 75, particularly preferably from 50 to 70, % by weight of dihydrodicyclopentadienyl acrylate are used as component Hl. 3, and from 0.1 to 25%
by weight, especially from 0.5 to 10, particularly preferably from 1 to 5, % by weight of divinylbenzene and/or butanediol diacrylate are used as component Hl.4.

The sums of the percentages by weight of a and ~ and the sums of the percentages by weight of Hl.l to P.1.1. 4 ~hould each be 100.

The choice of the crosslinkers depends on the form which ~he network of the hard segment is to have. A compact network is obtained, for example, if the preceding - ' CA 02266467 1999-03-24 crosslinker ~ is used with divinylbenzene and/or butane-diol diacrylate, preferably butanediol diacrylate, whereas a relatively loose network is formed if, for example, crosslinker ~ is used together with tetra-ethylene glycol diacrylate or dimethacrylate.

The particularly preferred crosslinker mixtures include dihydrodicyclopentadienyl acrylate and butanediol di-acrylate; dihydrodicyclopentadienyl acrylate and divinyl-benzene; dihydrodicyclopentadienyl acrylate and ethylene glycol diacrylate; and dihydrodicyclopentadienyl acrylate and tetreethylene glycol dimethacrylate. Further pre-ferred crosslinker mixture~ are dihydrodicyclopentadienyl acrylate, butanediol diacrylate and allyl methacrylate;
dihydrodicyclopentadienyl acrylate, butanediol diacrylate and hydroxyethyl acrylate; dihydrodicyclopentadienyl acrylate, butanediol diacrylate and divinylbenzene;
dihydrodicyclopentadienyl acrylate, hydroxyethyl acrylate and divinylbenzene or diethylene glycol diacrylate or tetraethylene glycol dimethacrylate; dihydrodicyclopenta-dienyl acrylate, hydroxyethyl acrylate, allyl meth-acrylate and di~inylbenzene or diethylene glycol di-acrylate or tetraethylene glycol dimethacrylate; dihydro-dicyclopentadienyl acrylate, allyl methacrylate, ~-methacryloyloxyethyldimethoxymethylsilane and divinyl-benzene or diethylene glycol diacrylate or tetraethylene glycol dimethacrylate; dihydroxydicyclopentadienyl acrylate,~-methacryloyloxyethyldimethoxymethylsilaneand divinylbenzene or diethylene glycol diacrylate or tetra-ethylene glycol dimethacrylate.

Other novel hard segments Hl preferably contain Hl.4 in ~mo~lt~ of from 0.5 to 5% by weight, based on the com-ponents Hl.l to Hl.4. In principle, the components Hl.3 and Hl.4 may be present in any ratio to one another.
~owever, preferred hard ~egments Hl contain the com-ponents Hl.3 and Hl.4 in a ratio of from 1:0.5 to 1:3.
-- CA 02266467 l999-03-24 Howe~er, the amount of the component H1.4 may also be lower and may be, for example, 1:0.3. Larger amounts of H1.4 are also suitable, for example up to 1:10 for H1.3:H1.4, the ratios of H1.3 to H1.4 preferably being from 1:0.5 to 1:3 or from 1:1 to 1:3, in particular from 1:0.5 to 1:2, particularly preferably from 1:0.75 to 1:1.

The novel hard segment H1 is prepared by varying the concentration of at least on crosslinker by metering in the one or more crosslinkers, it being particularly preferred if the variation, preferably increase, of at least one crosslinker having two or more functional groups of different reactivity, preferably dihydro-dicyclopentadienyl acrylate, is effected by metering in the one or more crosslinkers.

The novel hard segment H1 is preferably prepared by ~arying the metered amount of at least one crosslinker o~er the metering period.

The metering period is the time span which is defined by the beg; nn; ng and end of the addition of at least one monomer - in the case of the hard segment, of at least one vinylaromatic mo~omer as the mo~omer or as one of two or more mQnomers copolymerizable with one another and, in the case of the soft segment, of at least one acrylate as the mo~omer or as one of two or more monomers copolymer-izable with one another.

The variation of the metered amount of at least one crosslinker o~er the metering period may start and end at any desired time within the metering period. It is also po~ible $or the ~ariation or at least Gne cro~slinker over the metering period to start and end ~e~eral times.
The variation of at least one crosslinker may start after ?the first third, preferably after the first fourth, particularly preferably with the beg; nni ng of the CA 02266467 l999-03-24 metering period and _ay be ended before the beg;nn;ng of the last third, preferably before the beg;nn;ng of the last fourth, particularly preferably before the end of the metering period. These statements also apply to the beginning and end of the metering of the crosslinkers whose metered amount remains constant over the metering period.

In the preparation of the novel hard segment H1, it is preferable if the metered amount of at least one cross-linker having functional groups of different reactivity increase~ over the metering period. It is particularly preferable if the metered amount of at least one cross-linker having two or more functional groups of different reactivity increases over the metering period and the metered amount of at least one crosslinker having two or more functional groups of the same reactivity remains constant over the metering period.

Furthermore, it is preferable according to the invention if the hard segment H1 is prepared by emulsion polymer-ization in the aqueous phase in the presence of one or more emulsifiers and initiators at from 20 to 90~C.

The novel hard segments H1, preferably for grafting bases, are preferably prepared by a process wherein at least one vinylaromatic mo~omer, as the ~o~nmer or as one of two or more monomers copolymerizable with one another, and a crosslinker component which contains at least one crosslinker having two or more functional groups of different reactivity, preferably at least dihydrodicyclo-pentadienyl acrylate, are polymerized in a first step and thP product i3 polymerized, in a ~econd ~tep, with at least one vinylaromatic monomer as the monomer or as one of two or more monomerE copolymerizable with one another ~nd at least one crosslinker having two or more function-al groups of different reactivity, preferably at least .. .... ~. .~ . .

' " CA 02266467 1999-03-24 ~ - 23 -dihydrodicyclopentadienyl acrylate, and at least one crosslinker having two or more functional groups of the same reactivity, preferably at least divinylbenzene and/or butanediol diacrylate, the metered amount of at least one crosslinker varying over the metering period.
The preparation process described above for the novel soft segment Hl is particularly preferred if the metered amount of at least one crosslinker is varied over the metering period in the second step.

Furthermore, it is preferable according to the invention if, in the second step of the process described above, the metered amount of at least one crosslinker having functional groups of different reactivity increases over the metering period and the amount of at least one crosslinker having functional groups of the same reactiv-ity decreases over the metering period.

When the hard segment Hl is used as the grafting base, in particular in the case of the graft copolymers Pl'' and P2'', it is preferable to prepare the hard segment forming the grafting base by means of a seed latex in which preferably the metered amount of at least one crosslinker having two or more functional groups of different reactivity increases over the metering period, and by further addition of at least one mo~o~r, prefer-ably the same one, and of at least one further cross-linker, preferably that used in the seed latex. Here, it is particularly preferable if in addition at least one crosslinker having two or more functional groups of the same reactivity is added over the metering period for the addition of at least one further monomer. In this addition of at least on~ monom~r and at least one cro~s-linker, following the preparation of a seed latex, it is also advantageous if the metered amount of at least one crosslinker having two or more functional groups of different reactivity increases over the metering period.

. . ~ . . .

The two-step process described above is preferably used for the preparation of hard segments Hl which are used as the grafting base in a graft copolymer. Furthermore, it may be in accordance with the invention to use the two-step process for the preparation of hard segments which are used as the grafting base in a graft copolymer.

The two steps for the preparation of the novel hard segments Hl are preferably carried out as an emulsion polymerization, preferably in the aqueous phase, in the presence of one or more emulsifiers and initiators, which may be identical or different for each step, at tempera-tures which are identical or different for each step and are in the range from 30 to 90~C, preferably from 50 to 80~C, particularly preferably from 55 to 75~C.

For the preparation of the hard segments Hl, a cross-linked seed latex of the monomer Hl.lj preferably sty-rene, and a crosslinker ~ and/or ~, preferably dihydro-dicyclopentadienyl acrylate, is preferably first produced in one step. In general, the novel seed latex preferably has a mean particle size (d50) of from 20 to 150 nm, preferably from 50 to 100 nm. The seed latex is then reacted, in a further step, with further monomers Hl.l, preferably styrene, and crosslinkers, preferably cross-linkers having two or more functional groups of different reactivity and/or the same reactivity, emulsifiers, polymerization assistants and initiators to give the novel hard segments Hl.

It is also possible to prepare the hard segments Hl in a one-step process. In such a process, at least one viny.aromatic monomer, as the monom2r or a~ one of two or more mo~omers copolymerizable with one another, and a crosslinker component which contains at least one cross-linker having two or more functional groups of different reactivity, preferably at least dihydrodicyclopentadienyl ~ ' CA 02266467 1999-03-24 acrylate, and one crosslinker having two or more func-tional groups of the same reactivity, preferably at least divinylbenzene and/or butanediol diacrylate, are polymer-ized, the metered amount of at least one crosslinker varying over the metering period.

However, it is particularly preferable if the metered amount of at least one crosslinker having functional groups of different reactivity increases over the meter-ing period. Here too, suitable emulsifiers, initiators and polymerization assistants, such as surfactants, may be present.

Furthermore, the second step may be effected before the first step. In this case, at least one vinylaromatic monomer, as the monomer or as one of two or more monomers copolymerizable with one another, and one crosslinker component which contains at least one crosslinker having two or more functional groups of different reactivity, preferably at least dihydrodicyclopentadienyl acrylate, and at least one crosslinker having two or more function-al groups of the same reactivity, preferably at leastdivinylbenzene and/or butanediol diacrylate, are first polymerized and, in a subsequent step, at least one vinylaromatic monomer, as the mo~n~r or as one of two or more monomers copolymerizable with one another, and a crosslinker component which contains at least one cross-linker having two or more functional groups of different reactivity, preferably at least dihydrodicyclopentadienyl acrylate, are polymerized.

In this procedure, it should preferably be ensured that the metered amount of at least one crosslinker ~arie~
over the metering period, it being particularly prefer-able if the metered amount of at least one crosslinker paving functional groups of different reactivity in-creases over the metering period.

. . ~ ~

Furthermore the novel hard segments H1 can be prepared by processes having more than two steps, for example three, four, five, six and seven steps. In these multistep preparation processes, the steps may be combined in any sequence, the metered amount of at least one crosslinker varying over the metering period or, preferably, the metered amount of at least one crosslinker having func-tional groups of different reactivity increasing over the metering period.

The morphology of the hard segment H1 depends on the preparation variant. Thus, the hard segment H1 which was prepared in one step has a uniform morphology. The hard segments H1 which were prepared in two-step or multistep processes have different regions of different morphology, dep~n~;ng on the number of steps.

If the novel hard segment H1 is used as a grafting base, a preparation process having two or more steps is pre-ferred. Where the novel hard segment H1 is used as a graft layer, the preparation process t~k;ng place in one step is preferred.

The novel soft segments preferably have a glass transi-tion temperature of not more than 0~C, especially not more than - 20~C, particularly preferably from -100 to -30~C. The main particle size (d50) of the soft segments is up to 150 nm, in particular from 40 to 110 nm, parti-cularly preferably from 50 to 100 nm, if these are used as grafting bases in a graft copolymer. However, graft-ing bases comprising a soft segment having a mean par-ticle size (d50) of from 60 to 150 nm are particularly preferred.

The mean particle size (d50) of the soft segments may -likewise be from 100 to 2000 nm, preferably from 350 to 1000 nm, particularly preferably from 400 to 550 nm, if ' CA 02266467 1999-03-24 these are used as grafting bases in a graft copolymer.

The novel soft segments contain at least one acrylate as the ~Q~-r or as one of two or more mQ~omers copolymer-izable with one another and at least one crosslinker.

S If the novel soft segments are used as the grafting base, they preferably contain, as crosslinkers, at least one crosslinker having two or more functional groups of different reactivity and/or at least one crosslinker having two or more functional groups of the same reactiv-ity, the concentration of at least one crosslinker in the soft segment being varied.

When soft segments are preferably used as the grafting base, it is particularly advantageous if the concentra-tion of at least one crosslinker having two or more functional groups of different reactivity increases from the inside to the outside of the soft segment.

The novel soft segments will now be described by way of example with reference to the soft segment Pl'.1.

The novel soft segments Pl'.l are preferably composed of from 50 to 99.9, preferably from 75 to 99.9, particularly preferably from 90 to 99.9, % by weight of an acrylate (Pl'.l.l), from 0 to 50, preferably from 0 to 25, parti-cularly preferably from 0 to 10, % by weight of a monomer (P1'.1.2) copolymerizable with the monomer Pl'.l.l, and from 0.1 to 20, preferably from 0.1 to 5, particularly preferably from 0.1 to 3, % by weight of at least one crosslinker (Pl.1.3).

Further novel soft segments Pl'.l preferably contain at least one alkyl acrylate Pl'.l.l and, if desired, at least one monomer Pl'.1.2 copolymerizable with the ~onQ~?rs Pl'.l.l, and at least one crosslinker ~ or ~ or a mixture (P1'.1.3) thereof. According to the invention, the amount of the alkyl acrylates P1'.1.1 is preferably from 30 to 99.9% by weight, that of the monomers P1'.1.2 is from 0.1 to 50% by weight and that of the crosslinkerg P1'.1.3 is from 0 to 20% by weight. Preferably, the soft segments P1'.1 contain from 60 to 99.9, in particular from 65 to 99, % by weight of P1'.1.1, from 0 to 39.9, preferably from 0 to 30, % by weight of P1'.1.2 and from 0.1 to 10, preferably from 1 to 5, % by weight of P1'.1.3. The stated weights are each based on the sum of the components P1'.1.1 to P1'.1.3.

Preferred mono~ers P1'.1.1, preferably acrylates, parti-cularly preferably alkyl acrylates, preferably of not more than 20 carbon atoms, are alkyl acrylates, phenyl-alkyl acrylates or phenoxyalkyl acrylates of up to 18 carbon atoms, in particular those having 2 to 8 carbon atoms in the alkyl radical, alone or as a mixture. n-Butyl acrylate and ethylhexyl acrylates, eg. ethyl-n-hexyl acrylate, are particularly suitable. Furthermore, all other known ~o~mers forming rubber elastomers, such as dienes, for example 1,3-butadiene, and organosilo-xanes, such as dimethylsiloxanes, may be used.

Examples of the monomers P1'.1.2, preferably of not more than 20 carbon atoms are acrylic acid derivatives or methacrylic acid derivatives differing from P1'.1.1, including preferably the esters or amides thereof. In addition, styrene, styrene substituted on the nucleus, ~-methylstyrene, acrylonitrile and dienes, such as buta-diene or isoprene, are suitable as copolymerizable ~o~o~ers P1'.1.2. It is of course also possible to use mixtures of different monomers ~1'.1.2. The monomers P1'.1.2 should be copolymerizable with the monomers P1'.1.1.

Preferred crosslinkers Pl'.1.3 are one or more of the conventionally used, crossl;n~;n~ mono-ers, which may be employed either individually or as a mixture with one another. A preferred crosslinker component may contain dihydrodicyclopentadienyl acrylate (~) alone or in combination with at least one other crosslinker having two or more functional groups of different reactivity (~). According to the invention, the crosslinker com-ponent preferably consists of from 0.1 to 100, preferably from 25 to 100, in particular from 30 to 100, % by weight, based on ~ and ~, of ~ and from 0 to 99.9, preferably from 0 to 75, particularly preferably from 0 to 70, % by weight, based on ~x and ,~, of ,l~. Particularly preferably, the crosslinker component contains from 50 to 100% by weight of ~ and from 0 to 50% by weight of ~.

Examples of suitable crosslinkers ~ and ~ for the soft segment P1'.1 correspond to the crosslinkers ~ and ~
mentioned for H1. The mixtures of the crosslinkers ~ and preferred in the case of H1 are also preferred here in the case of P1'.1. The list of further suitable cross-linkers H1.4 also applies to suitable crosslinkers P1'.2.3 having two or more functional groups of the same reactivity.

The choice of the crosslinker P1'.1.3 depends, for example, on the network which the soft segment P1'.1 is to have, either as grafting base or as graft layer. A
compact network is obtained, for example, if crosslinker is used together with divinylbenzene and/or butanediol diacrylate, whereas a relatively loose network is ob-tained if, for example, crosslinker ~ is used with tetraethylene glycol diacrylate or dimethacrylate.

The particularly preferred crosslinker mixtures include dihydrodicyclopentadienyl acrylate and butanediol di-,acrylate; dihydrodicyclopentadienyl acrylate and divinyl-benzene; dihydrodicyclopentadienyl acrylate and di-~ ~ CA 02266467 1999-03-24 ethylene glycol diacrylate; and dihydrodicyclopentadienyl acrylate and tetraethylene glycol dimethacrylate.
Further crosslinker mixtures for the soft segments P1'.1 correspond to the lists of crosslinker mixtures for the hard segment H1.

In the soft segments P1'.1, crosslinkers having two or more functional groups of the same reactivity and cross-linkers having two or more functional groups of different reactivity may thus be present, each alone or in combination.

The soft segments can be prepared either in one step or in a plurality of steps, for example 2, 3, 4, 5 or 6, preferably two or three, particularly preferably two, steps. If a no~el soft segment is used as the grafting base, the preparation of a seed latex in the form of a one-step synthesis is particularly preferred.

An embodiment of the one-step synthesis of the soft segment is present when either a crosslinker having two or more functional groups of the same reactivity or a crosslinker having two or more functional groups of different reactivity is used. In a further embodiment, one or more crosslinkers of both generic types can be used in the one-step synthesis. The one-step synthesis can be used for the preparation of both grafting bases and graft layers comprising soft segments.

Furthermore, grafting bases and graft layers comprising soft segment can be prepared by a ~ultistep synthesis.
The one-step or multistep synthesis is carried out similarly to the ~orresponding ~ynthe~es of Hi, using the monomers and crosslinkers described above by way of example for P1'.1.
.~
If the synthesis is carried out in one step, the soft ~ CA 02266467 1999-03-24 segment generally has a uniform morphology. If the synthesis i8 carried out in a plurality of steps, the soft segment may have a morphology comprising different phases.

However, it may also be preferable, according to the invention, to prepare the soft eegments without varying the metered amount of one or more crosslinkers. However, it is particularly preferred according to the invention if, in a novel graft copolymer, the concentration of at least one crosslinker is also varied in at least one soft segment of this graft copolymer in addition to the variation of at least one crosslinker in a hard segment.
The graft copolymer having a soft segment as a grafting base, in which the concentration of at least one cross-linker is varied only in this soft segment and in thesubsequent hard segment, is preferred over and above this in this context, the soft segment preferably being present in the form of a seed latex and the statements with regard to the seed latex under hard segment Hl being applied to this case. The further soft segments of this graft copolymer exhibit no variation of the crosslinker concentration.

In general, it is true for the preparation of soft segments whose crosslinker concentration varies that the metered amount of at least one crosslinker varies over the metering period, preferably the metered amount of at least one crosslinker having functional groups of differ-ent reactivity increases over the metering period.

The soft segments preferably have, as a rule, gel con-~0 tent~ of at least 90%, praferably at least 95%, and swelling indices of in general from 7 to 15.

Furthermore, the novel graft copolymers Pl and P2 representative of Pl' and P1'' on the one hand and P2' and P2'' on the other hand - may preferably contain at least one, especially from 1 to 7, particularly prefer-ably from 1 to 3, additional segments, namely Pl.3 and P2.4, respecti~ely, this segment or these segments preferably accounting for from 0.1 to 90, particularly preferably from 5 to 50, % by weight of the graft copoly-mer then formed. This segment, referred to below as Pl.3 as representative of P1.3 and P2.4, preferably contains at least one ~inylaromatic monomer as mentioned specifi-cally under Hl.l. Moreover, Pl.3 can, if required,contain further mo~omers, preferred ~o~ers being those which are copolymerizable with the ~inylaromatic mo~Q~?r.
If required, the segment Pl.3 may contain one or more crosslinkers, the crosslinkers described under H1 being particularly preferred. P1.3 preferably consists of one or more polymer compositions P1.3.1 and P1.3.2, prefer-ably in any desired sequence. According to the inven-tion, it is particularly preferable if the polymer compositions Pl.3.1 and Pl.3.2, beg; nn;ng with Pl.3.1, alternate with one another. The number of successive and preferably alternating polymer compositions P1.3.1 and P1.3.2 is from 2 to 10, preferably from 2 to 7, parti-cularly preferably from 2 to 5.

A particularly preferred segment Pl.3 contains, in any desired ~eguence, preferably in thi~ sequence, a polymer composition Pl.3.1, containing Pl.3.1.1) from 30 to 99.9% by weight of at least one ~inylaromatic monomer, P1.3.1.2) from 0 to 50% by weight of at least one ~o~nmer copolymerizable with P1.3.1.1, P1.3.1.3) from 0.1 to 20% by weight of a crosslinker or ~ or mixtures thereof and/or, preferably and, a second polymer composition P1.3.2, containing P1.3.2.1) from 50 to 100% by weight of at least one vi~ylaromatic monomer and .

' CA 02266467 1999-03-24 Pl.3. 2.2) from 0 to 50% by weight of at least one monomer copolymerizable with Pl.3. 2.1, the sum of the percentages by weight of Pl.3.1..1 to Pl.3.1.3 and of Pl.3.2.1 to P.1.3.2.2 each being 100.

Where a plurality of polymer compositions Pl.3.1 and/or Pl.3.2 succeed one another, it is preferably according to the invention if the compositions of the individual com-ponents of the successive polymer compositions can vary within the abovementioned limits.

The preparation of the segment Pl.3 can be carried out in one step or in a plurality of steps. A synthesis in one step is preferred when no crosslinker or only one cross-linker is used. A preparation performed in a plurality of steps is advantageous when two or more crosslinkers are used. The preparation performed in a plurality of steps is particularly preferred for polymer compositions of the type Pl.3.1. The statements made with regard to the preparation of the hard segment H1 are also appli-cable to the preparation performed in one or more stepC, the variation of the metered amount of crosslinker preferably not being important here.

In general, the grafting bases P1.1 and P2.1 used in the novel graft copolymers P1 and P2, respectively (the following data also apply to P1' and P1'' and to P2' and to P2'') have a mean particle size (d50) of from 60 to 150 nm, preferably from 80 to 120 nm, particularly preferably from 85 to 110 nm.

Grafting base and first graft layer of the novel graft ~opolymers P1 and P2 preferably have a mean particle ~ize (d50) of from 200 to 800 nm, especially from 200 to 500 nm, particularly preferably from 200 to 350 nm.

The novel graft copolymer P2 with first and second graft layers has a mean particle size of from 300 to 1500 nm, preferably from 350 to 800 nm, particularly preferably from 400 to 550 nm.

The novel graft copolymers Pl and P2, together with the segments P1.3 and P2.4, respectively, preferably each have a mean particle size (d50) of from 350 to 2,000 nm, especially from 400 to 800 nm, particularly preferably from 450 to 600 nm.

The graft copolymerization for the preparation of novel graft copolymers P1 and P2 is preferably controlled in general in such a way that the weight ratios of the grafting bases, preferably compri6ing soft segments, and of the graft layers, preferably comprising hard segments, are from 1:1 to 1:100, preferably from 1:10 to 1:50.
Other preferred novel graft copolymers have a weight ratio of soft segment to hard segment of from 1:20 to 1:40. The graft layers of the novel graft copolymers P1 and P2 can in principle have any layer thicknes6; they preferably have an average layer thickness of either up to 120 nm, preferably from 10 to 110 nm, particularly preferably from 20 to 100 nm, or from 100 to 2000 nm, preferably from 350 to 1000 nm, particularly preferably from 450 to 600 nm. The average layer thickness is developed from the individual layer thicknesses according to the mean particle size.

The graft copolymer may have either a narrow or a broad particle size or layer thickness distribution. They preferably have a narrow particle size or layer thickness distribution. The particle size distribution is defined a8 the quotient Q = (dgo ~ dlo)/dso The dlo ~~~ the dgo value is defined similarly to the d50 value, except that it is based on 10 and 90% by weight, respectively, of the particles. Further preferred novel graft copolymers P1 and P2 have Q values of 5 0.3, preferably 5 0.15, parti-J ' CA 02266467 1999-03-24 cularly preferably from 0.15 to 0.01. The abo~e state-ment also applies to the layer thickness distribution.

Even in the case of large particle ~izes of the grafting base, for example of from 400 to 800 nm, or if substan-tially more grafting base is present in relation to the grafting bases following the graft layer, for example with a weight ratio of grafting base to graft layer of from 1:1 to 50:1, particularly preferably from 5:1 to 20:1, the no~el graft copolymers preferably ha~e a virtually perfect core-shell morphology. The grafting base forms a core with defined phase boundaries with the graft layer. This is surrounded essentially concentric-ally by the graft layer. As a rule, the width of the phase boundary between the grafting base and the graft layer and that between the ~arious graft layers is on average at least 50 nm, preferably at least 10 nm, particularly preferably at least 5 nm, or in the range from 0.1 to 50 nm, preferably from 0.1 to 10 nm, particu-larly preferably from 0.01 to 5 nm.

The width of the phase boundary can be determined by electron microscopy. For this purpose, sections ha~ing a thickness of less than 100 nm are prepared by means of a cryo-ultramicrotome and are coated with ruthenium tetroxide by vapor deposition for 20 minutes at 30~C.

2 5 Only the particles cut along the equator are measured, and the mean value of the distance of the phase bound-aries of 10 particles to be e~aluated is determined.

In addition to the width of the phase boundary of the novel graft copolymers P1 and P2, it is also possible to control the type of transition ~t the pnase boundary. A
sharp transition or a diffuse transition may be present in the graft copolymers. Graft copolymers having a sharp ~ransition preferably have a very narrow phase boundary with an abrupt phase transition. The width of the phase ' CA 02266467 1999-03-24 boundary in the case of sharp transitions is from 0.1 to 10 nm, preferably from 0.1 to 5 nm, particularly prefer-ably from 0.1 to 3 nm. Preferred graft copolymers having a diffuse transition are those in which the diffuse transition is very uniform along a straight line r~nn;ng from the grafting base, viewed from the inside to the outside. In the case of the diffuse transitions, larger phase boundary ranges are preferred, for example from 0.1 to 5 nm, preferably from 4 to 10 nm, particularly preferably from 10 to 100 nm.

According to the invention, the width and the type of the transition are preferably controlled by varying the crosslinkers. However, it is also preferable according to the invention if the control is effected by the combination of the crosslinker variation and the choice of suitable feed rates.

Thus, in a novel embodiment, a sharp phase transition can be produced by decreasing the concentration of at least one crosslinker having two or more functional groups of the same reactivity and by means of a small ratio of the feed rates. A decrease of at least one crosslinker having two or more functional groups of the same reactiv-ity and a large ratio of the feed rates results in a diffuse phase transition. In an embodiment in which at least one crosslinker having two or more functional groups of different reactivity increases and the ratio of feed rates is small, a sharp phase transition i8 formed.
However, if the concentration of at least one crosslinker having two or more functional groups of different reac-tivity decreases and the ratio of the feed rates to oneanother is larger, a diffuse phase tran~ition is prefer-ably formed. In a further novel embodiment, a sharp phase transition is preferably formed when both at least ~ne crosslinker having two or more functional groups of the same reactivity and at least one crosslinker having CA 02266467 l999-03-24 two or more functional groups of different reactivity decrease in their concentration, this being the case with a small ratio of the feed rates. The ratio of the feed rates F1 to F2 is described by way of example with reference to graft copolymer Pl.

F1 correspond6 to the amount of monomers and crosslinker6 P1.1.1 to P1.1. 4 [g/h]/amount of the mo~mer6 Pl.2.1-to Pl.2.3 ~g/h]; F2 is equal to the amount of emul6ifier for P1.1 ~g/h~/amount of emul6ifier for Pl.2 ~g/h].

Small ratios of the feed rates which are preferred according to the invention are from 0.05 to 1, preferably from 0.1 to 0.99, particularly preferably from 0.2 to 0.75. Large ratios of the feed rate6 which are preferred according to the invention are from 1 to 10, preferably from 1 to 5, particularly preferably from 1 to 3.

The preparation of the novel graft copolymers can be carried out by the method6 disclosed, inter alia, in DE-B-12 60 135, DE-A-23 11 129, DE-A-28 26 925, EP-A-81 761, EP-A-450 485 and US-A-3 691 260.

In the preparation of the novel graft copolymers, it i6 preferable to note that they are prepared by emulsion polymerization in an aqueous phase, in which the varia-tion in the concentration of at lea6t one cro6slinker is effected by metering in the one or more crosslinkers, it being preferable if the variation, preferably increase, in the concentration of at least one crosslinker having two or more functional groups of different reactivity, preferably dihydrodicyclopentadienyl acrylate, is effect-ed by metering in the one or more cros~iinker~. Varying the concentration is understood as meaning in each case varying the concentration of at least one crosslinker in tlhe correspon~;ng segment.

' CA 02266467 1999-03-24 First, the grafting base is polymerized from its com-ponents, preferably in aqueous emulsion at from 20 to 100~C, especially from 40 to 80~C, particularly prefer-ably from 50 to 70~C. Conventional emulsifiers, for example alkali metal salts of alkanesulfonic or alkyl-arylsulfonic acids, alkylsulfates, fatty alcohol sul-fonates, salts of higher fatty acids of 10 to 30 carbon atoms or resin soaps, may be used. The potassium or sodium salts of alkanesulfonates or of fatty acids of 10 to 18 carbon atoms are preferably used for this purpose.
It is advantageous to use the emulsifiers in an amount of from 0.1 to 5, preferably from 0.2 to 2, % by weight, based on the total weight of the monomers used for the preparation of segments forming the grafting base.

In general, a water/mo~o~er ratio of from 4:1 to 0.7:1, preferably from 2:1 to 0.8:1, particularly preferably from 1.5:1 to 1:1, i8 used. The polymerization initia-tors used are in particular the conventional persulfates, for example potassium peroxodisulfate; however, redox -20 systems are also suitable. The amount of the initiators - for example from 0.1 to 2.5% by weight, based on the total weight of the monomers - depends in a known manner on the desired molecular weight conventional buffer substances by means of which the pH can be brought to, preferably, 6-9, for example sodium bicarbonate and sodium pyrophosphate, and up to 3% by weight of a molecu-lar weight regulator, such as mercaptans, terpinol or ~-methylstyrene, may be used as polymerization assistants.

The first graft layer is applied to the grafting base by polymerizing the components of the segments forming the graft layer in ~he presence of the graf~:ing base, which is preferably a latex. This is preferably effected in an aqueous emulsion under the same conditions as described in the case of the preparation of the grafting base.

. .

- ' CA 02266467 1999-03-24 The graft layer can be applied to the grafting base in one step or in a plurality of steps, the reaction being carried out in five, preferably three, particularly preferably two, steps.

The next graft layers are applied to the copolymer, consisting of grafting base and first graft layer, by polymerizing the components of the segments forming the further graft layer with one another in the presence of this copolymer. This is preferably effected in an aqueous emulsion under conditions similar to those described in the case of the preparation of the copolymer comprising grafting base and first graft layer.

It is advantageous to carry out the graft copolymeriza-tion of each additional graft layer, for example P2. 3, once again in aqueous emulsion in the presence of the graft copolymers consisting of grafting ba~e and two graft layere. However, the graft copolymerization can also be carried out by the suspension, mass or solution method. It may be effected in the system of the polymer-izations preceding it, and it may be preferable to addfurther emulsifier and initiator, which need not corres-pond to those used before. The statements made with regard to the preparation of the grafting base are applicable to the choice and combination of emulsifiers.

The novel graft copolymers are obtainable in particular by a process in which the segments forming the grafting base and the corresponding graft layers are polymerized from their monomers in succession in an emulsion at from 20 to 90~C, preferably from 50 to 80~C, particularly preferably from 55 to 75~C. It may be partlcularly preferable according to the invention if the reaction temperatures for the preparation or grafting-on of a hard ~segment are from 20 to 80~C, preferably from 40 to 80~C, particularly preferably from 60 to 80~C. Where a soft .. . . . .

' CA 02266467 1999-03-24 segment is prepared or grafted on, it i8 particularly preferable if the reaction temperature iB from 20 to 80~C, preferably from 50 to 70~C, particularly preferably from 60 to 70~C.

The type of phase transition between two segments may be controlled by the amount of residual monomer of the segment first polymerized in the polymerization of the subseguent segment. The higher the proportion of resi-dual ~7~m-rs, the more diffuse i8 the phase transition between the two segments.

The novel hard segments Hl and graft copolymers Pl and P2 can be used both alone and as a mixture with other graft copolymers or copolymers. They are preferably suitable as impact modifiers for, preferably in, thermoplastic materials. The novel graft copolymers Pl and P2 are particularly suitable as impact modifiers for thermo-plastics which have a glass transition temperature of at least 25~C, preferably at least 60~C, particularly preferably at least 80~C. Examples are polyvinyl chlor-ide (PVC), polymethyl methacrylate and copolymers ofvinylaromatic ~Q~Qm~rs and polar copolymerizable, ethylenically unsaturated monomers and mixtures thereof.

Particularly preferred copolymers are styrene/
acrylonitrile copolymers or ~-methylstyrene/acrylonitrile copolymers. In addition, the thermoplastic, likewise novel materials may contain other thermoplastics, in particular polycarbonates.

The preferred thermoplastic materials (Tl) include those which contain Tl.i) from 0.1 to 95% by weight of at least one of the graft copolymers Pl to P5 and at least one of the mixtures Ml to M5, Tl.ii) from 0 to 94.9% by weight of at least one graft - ~ CA 02266467 1999-03-24 copolymer and/or mixture differing from Tl.i, Tl.iii) from 5 to 99.9% by weight of at least one copoly-mer of Tl.iii.1) from 50 to 100% by weight of at least one vinylaromatic mo~nmer~ C1-Cl8-alkyl acrylate, C1-C18-alkyl methacrylate or mixtures thereof, Tl.iii.2) from 0 to 50% by weight of acrylo-nitrile, methacrylonitrile, maleic anhydride, N-substituted maleimides or a mixture thereof, the sum of the per-centages by weight of Tl.iii.1 and Tl.iii.2 being 100, Tl.iv) from 0 to 90% by weight of at least one poly-carbonate and Tl.v) from 0 to 50% by weight of additives, the sum of Tl.i to Tl.iv being 100.

Furthermore, it is particularly preferred according to the invention if small-particled and large-particled graft copolymers of Pl and of P2, respectively, are preferably used in the thermoplastic materials. These mixtures contain from 10 to 95, preferably from 30 to 90, particularly preferably from 60 to 85, % by weight of the small-particled graft copolymer and from 5 to 90, prefer-ably from 10 to 70, particularly preferably from 15 to 40, % by weight of the large-particled graft copolymer.

Preferred graft copolymers ii are composed of a grafting base comprising a material having a glass tran~ition temperature of at least 25~C, preferably at least 80~C, in particular 80 - 130~C, ie. a hard, nonresilient material. These graft copolymerr3 ii contain two or more graft layers; preferably, they contain not more than three graft layers.
, Preferred graft copolymers ii contain _ CA 02266467 1999-03-24 ii.1) 5- 90% by weight of a grafting base of a material having a glaes transition temperature of at least 25~C, comprising ii.1.1) 50 - 99.9~ by weight of at least one ~inylaromatic mo~m~r, ii.1.2) 0 - 49.9% by weight of at least one mon~m~r copolymerizable with ii.l.l and ii.1.3) 0.1 - 10% by weight of at least one crosslinker and ii.2) 4.9 - 90% by weight of a graft layer of a materi-al ha~ing a glass transition temperature of not more than 0~C, comprising ii.2.1) 50 - 100% by weight of at least one C1-C1O-alkyl acrylate, diene or dialkyl-siloxane, ii.2.2) 0 - 50% by weight of at least one monomer copolymerizable with the mono-mers ii.2.1 and ii.2.3) 0 - 20% by weight of at least one crosslinker and ii.3) 0.1 - 85% by weight of a second graft layer of a material having a glass transition temperature of at least 25~C, comprising ii.3.1) 50 - 100% by weight of at least one vinylaromatic monomer, ii.3.2) 0 - 50% by weight of at least one mo~omer copolymerizable with the mono-mer ii.3.1 and ii.3.3) 0 - 20% by weight of at least one crosslinker and ii.4) 5 - 90% by weight of a third graft layer of a material having a glass transition temperature of at least 25~C, comprising ii.4.1) 1 - 99% by weight of at least one vinylaromatic monomer ii.4.2) 1 - 90% by weight of at least one monomer copolymerizable with the mono-mer ii.4.1), where the sums of the percentages by weight of the indi~i-dual component group6 should be 100%
in each case.

Particularly preferred graft copolymers ii contain 5 - 20% by weight of ii.l, 40 - 65% by weight of ii.2, 10 - 25% by weight of ii.3 and 10 - 40% by weight of ii.4, the sum of the components ii.l to ii.4 being 100.

The grafting base ii.l is preferably composed of 60 -99.8, in particular 70 - 99.5, % by weight of ii.1.1, 0 - 39.8, in particular 0 - 29.5, % by weight of ii.1.2 and 0.1 - 10, in particular 0.5 -3, % by weight of ii.1.3.

Preferred graft copolymer6 ii are composed of a grafting base of a material having a glass transition temperature of not more than 0~C, preferably not more than -10~C, in particular of -30~C, ie. a soft, resilient material.
These graft copolymers ii contain two or more graft layers; they preferably contain not more than three graft layers.

Further preferred graft copolymers ii contain ii.l) 4.9 - 94.9% by weight of a graft layer of a material having a glass transition temperature of not more than 0~C, comprising ii.1.1) 50 - 100% by weight of at lea6t one C1-' CA 02266467 1999-03-24 C18-alkyl acrylate, diene or dialkyl-siloxane, ii.l.2) 0 - 50% by weight of at least one monnm~r copolymerizable with the mono-mers ii.2.1 and ii.l.3) 0 - 20% by weight of at least one crosslinker and ii.2) 0.1 - 85% by weight of a second graft layer of a material having a glass transition temperature of at least 25~C, comprising ii.2.1) 50 - 100% by weight of at least one vinylaromatic monomer, ii.2.2) 0 - 50% by weight of at least one mo~om?r copolymerizable with the mono-mer ii.3.1 and ii.2.3) 0 - 20% by weight of at least one cros~linker and ii.3) 5 - 90% by weight of a third graft layer of a material having a glass tran~ition temperature of at least 25~C, comprising ii.3.1) 1 - 99% by weight of at least one vinylaromatic mo~Qmer and ii.3.2) 1 - 99% by weight of at least one monomer copolymerizable with the mono-mer ii.3.1), where the sums of the percentages by weight of the indivi-dual component groups should be 100 in each case.

Further particularly preferred graft copolymers ii 3C contain 5 - 50% by weight of ii.1, -~0 - 65% by weight of ii.2 and 10 - 30% by weight of ii.3, '- CA 02266467 l999-03-24 the sum of the components ii.1 to ii. 3 being 100.

The grafting base ii.1 is preferably composed of 60 -99.8, in particular 70 - 99.5, % by weight of ii.1.1, 0 -39.8, in particular 0 - 29.5, % by weight of ii.1.2 and 0.1 - 10, in particular 0.5 - 3, % by weight of ii.1. 3.

The preceding statements for soft and hard segments ha~ing ~imilar composition are applicable to the choice of monomers and of crosslinkers and to preparation processes and mean particle diameters, etc. The graft copolymers ii can be prepared by methods known per se, 80 that reference is made here to, for example, EP-A-450 485.

As a rule, materials which contain only the components iand ii form a bimodal particle mixture.

In addition to the components i and ii, the material may contain, as component iii, one or more copolymers in amounts of, preferably, 5 - 95% by weight, based on the components i to ~. Preferred molding materials contain 20 - 79.9, in particular 40 - 74.9, % by weight, based on the component i to v, of the component iii.

Preferred copolymers contain 60 - 80% by weight, based on the components iii.1 and iii. 2, of monomers iii.1 and 20 - 40% by weight, based on the components iii.1 and iii.2, of morlomers iii. 2.

Preferred copolymers iii are those which comprise at least one mo~o~er selected from the group consisting of styr~ne, ~-methylstyrene, 3tyrenes substituted on the nucleus, such as p-methylstyrene, and methyl meth-acrylate, copolymerized with at least one monomer select-~d from the group consisting of acrylonitrile, meth-acrylonitrile and maleic anhydride.

Particularly preferred copolymers iii are those compris-ing styrene, acrylonitrile and, if required, methyl methacrylate. Other particularly preferred copolymers iii contain a-methylstyrene, acrylonitrile and, if required, methyl methacrylate. In addition, copolymers iii comprising styrene, a-methylstyrene and acrylonitrile and, if required, methyl methacrylate are particularly preferred. Copolymers of styrene and maleic anhydride are also among the particularly preferred copolymers iii.
The copolymers iii are as a rule resin-like, thermo-plastic and rubber-free.

In a further embodiment, the thermoplastic materials and the components present therein, in particular the novel graft copolymers and mixtures thereof as well as the components ii and iii, are rubber-free, in particular diene rubber-free, particularly preferably butadiene rubber-free and/or isoprene rubber-free, in order to comply with DIN 16777/2 and ISO 6402/1.

The copolymers iii are known per se or can be prepared by methods known per se, for example free radical polymer-ization, in particular emulsion, suspension, solution or mass polymerization. They have in general vi~cosity numbers of 40 - 60, preferably 60 - 100, ml/g. This corresponds to weight average molecular weights Mw of from 50,000 to 250,000 g/mol. The copolymers iii may likewise have a molecular weight of from 1500 to 50,000 g/mol. In addition the copolymers iii may prefer-ably be present as a mixture of only the low molecular weight copolymers iii having a molecular weight of from 1500 to 50,000 g/mol or as a mixture with the high molecular weight copolymer~ iii having a molecular weight of from 50,000 to 250,000 g/mol.

The copolymers iii are often also formed as byproducts in the graft copolymerization for the preparation of the no~el graft copolymers P1 to P5, particularly when large amounts of mo~ rs are grafted onto small amounts of grafting base.

The materials may contain 0 - 90, preferably 0 - 80, % by weight of at least one polycarbonate as component iv.

The polycarbonates iv are known per se and are described in the literature.

These polycarbonates can preferably be prepared by reacting carbonic acid derivatives, such as phosgene or diphenyl carbonate, with diphenols. It iB possible in principle to use all diphenols, as mentioned, for exam-ple, in the monograph by ~. Schnell, Chemistry and Physics of Polycarbonates, Interscience Publishers, 1964, and in US-A-2 999 835 and DE-A-22 48 817.

Dihydroxydiphenyl, di(hydroxyphenyl)alkanes and di-(hydroxyphenyl) ether and mixtures thereof are particu-larly preferred diphenols.

Suitable diphenols are, for example, 1,3-dihydroxy-benzene, 1,4-dihydroxybenzene, 2,6-dihydroxynaphthalene, di(4-hydroxyphenyl)methane, 1,1-di(4'-dihydroxyphenyl)-ethane, 2,2-di(4'-hydroxyphenyl)propane (bisphenol A), 2,2-di(3'-chloro-4'-hydroxyphenyl)propane, 2,2-di(3',5'-dichloro-4'-hydroxyphenyl)propane, 2,2-di(3',5'-dibromo-4'-hydroxyphenyl)propane, 2,2-di(3',5'-dimethyl-4'-hydroxyphenyl)propane, 2,4-di(4'-hydroxyphenyl)-2-methyl-butane, di(4'-hydroxyphenyl)pentane, 1,1-di(4-hydroxy-phenyl)cyclohexane, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydlphenyl sulfite and 4,4~-dihydroxydiphenyl ether.

~IParticularly preferred diphenols are bisphenol A and-its mixtures with other diphenols. The amount of bisphenol ~ ' CA 02266467 l999-03-24 A in such mixtures i8 in general 70 - 98% by weight.

Both homopolymers and copolymers of mixtures of different diphenols may be used. It is also possible to use block copolymers, such as diorganosiloxane-containing polycarbonates.

The polycarbonate iv can be branched by incorporating small amounts, for example from 0.05 to 2 mol %, based on the sum of the diphenols used, of compounds having a functionality of three or more, such as those having three or more phenolic OH groups.

Processes for the preparation of polycarbonate iv are known per se. Thus, the polycarbonates can be prepared, for example, in the heterogeneous phase, ie. by the phase boundary method, or in the homogeneous phase, ie. by the pyridine method. Processes for the preparation of polycarbonate are described, for example, in DE-A-22 48 817, 13 00 266, 14 95 739 and 33 34 782 and in US-A-2 999 835.

The relative viscosity of the polycarbonates iv is in general 1.2 - 1.5, preferably 1.28 - 1.4, dl/g, measured in 0.5% strength by weight solution in dichloromethane at 25~C.

The thermoplastic materials may contain additives as components v. The amount thereof is in general O - 50, preferably 0.1 - 20, % by weight, based on the total weight of the components i to v.

Conventional additives are, for -x-mple, gl~ss fibers, flameproofing agents, stabilizers and antioxidants, heat stabilizers and W stabilizers, lubricants and mold 3 0 release agents, dyes and pigments and plasticizers.

Glass fibers comprising E, A or C glass may be used. In general, the glass fibers are pro~ided with a size and an adhesion promoter. The diameter of the glass fibers is in general from 6 to 20 ~m. Both ro~ings and cut glass fibers having a length of 1 - 10 mm, preferably 3 - 6 mm, may be incorporated.

Pigments and dyes are present in general in amounts of up to 6, preferably 0.5 - 5, in particular 0.5 - 3, % by weight, based on the components i to ~.

The pigments for coloring thermoplastics are generally known, cf. for example R. Gachter and H. Muller, Taschen-buch der Runststoffadditi~e, Carl Hanser Verlag, 1983, pages 494-510. A first preferred group of pigments comprises white pigments, for example zinc oxide, zinc sulfide, lead white (2 PbCO3 ~ Pb(OH)2), lithophone, antimony white and titanium dioxide. Of the two most co~-o~ly used crystal modifications (rutile and anatase type) of titanium dioxide, in particular the rutile form is used for imparting whiteness to the molding materials.

Black pigments which may be used are, for example, iron oxide black (Fe3O4), spinel black (Cu(Cr,Fe)2O4), manga-nese black (mixture of manganese dioxide, silica and iron oxide), cobalt black and antimony black and particularly preferably carbon black, which is generally used in the form of furnace black or gas black (cf. in this context G. Benzing, Pigmente fur Anstrichmittel, Expert-Verlag (1988), page 78 et seq.).

It is of course possible to use inorganic colored pig-ments, such a3 chrGme oxide green, or organic colored pigments, such as azo pigments or phthalocyanines, for obt~; n; ng certain hues. Such pigments are in general commercially available.

Antioxidants and heat ~tabilizers which may be added to the novel thermoplastic materials are, for examp}e, halides of metals of group I of the Periodic Table, for example sodium, potas~ium and lithium halides, if neces-sary in combination with copper(I) halides, for example chlorides, bromides or iodides. The halides, in particu-lar of copper, may also contain electron-rich 7r ligands.
Examples of such copper complexes are copper halide complexes with, for example, triphenylphosphine. Zinc fluoride or zinc chloride may also be used. Sterically hindered phenols, hydroquinones, substituted members of this group, ~econdary aromatic amines, if necessary in combination with phosphorus-cont~; n; ng acids, for example the salt~ thereof, and mixtures of these compounds may also be employed, preferably in concentrations of up to 1% by weight, based on the components i to v.

Examples of W stabilizers of various substituted resor-cinols, salicylates, benzotriazoles and benzophenones, which are used in general in amounts of up to 2% by weight, based on the components i to v.

Lubricants and mold release agents, which are generally added to the thermoplastic material in amounts of up to 1% by weight, are stearic acid, stearyl alcohol, alkyl stearates and stearamides as well as esters of penta-erythritol having long-chain fatty acids. Salts of cal-cium, zinc or of aluminum with stearic acid and dialkyl ketones, for example distearyl ketone, may also be used.

Examples of plasticizers are dialkyl phthalates, for example dioctyl phthalate.

The thermoplastic material can preferably be prepared by methods known per se, by mixing the components in conven-~tional m;Y;ng apparatuses, for example screw extruders, Brabender mills or Banbury mills, and then carrying out extrusion. After the extrusion, the extrudate is cooled and comminuted. The thermoplastic materials are dis-tinguished by high impact strength, in particular at low temperatures. At the same time, the thermoplastic materials have high weathering resistance and aging resistance. Moreover, they can be readily colored. In thermoplastic materials containing novel small-particled graft copolymers which preferably have a mean particle size (d50) of not more than 200 nm, the mechanical properties are in particular independent of the processing temperature, and further properties, in particular the colorability, are preferably the same or better.

They can be processed to give moldings, films, coatings or fibers. They can also be applied, for example by means of known coextrusion methods, in the form of layers (preferably having layer thicknesse~ of from 100 ~m to 10 mm) on surfaces, preferably on thermoplastics, such as styrene/acrylonitrile copolymers, acrylonitrile/buta-diene/styrene terpolymers (ABS), methyl methacrylate/butadiene/styrene (MABS), polystyrene, high impact polystyrene (HIPS) or PVC. The materials can be used, for example, in the automotive sector and household sector and for leisure articles. They can be processed, for example, to give automotive parts, road signs, window profiles, lamp covers, garden furniture, boats, surf-boards or toys.

An embodiment of the graft copolymer P1', preferred according to the invention and having a defined core-30 shell morphology, contains P1'.1) from 0.1 to 99.8% by weight of at least one grafting base comprising a soft segment having a glass transition temperature of not more than 0~C and a mean particle size (d50) of at least 50 nm, composed of - '' CA 02266467 1999-03-24 P1'.1.1) from 50 to 100% by weight of at least one acrylate, Pl'.1.2) from 0 to 50% by weight of at least one mons~mer copolymerizable with the monomer P1 ' .1.1 and Pl'.1.3) from 0 to 20% by weight of at least one crosslinker a or ,~ or a mixture thereof, whose concentration in-creases from the inside to the out-side of the grafting base, Pl'.2) from 0.1 to 99.8% by weight of at least one graf t layer comprising a hard segment having a glass transition temperature of at least 25~C, composed of Pl'.2.1) from 50 to 99.8% by weight of at least one vinylaromatic mo~omer, Pl'.2.2) f rom 0 to 49.8% by weight of at least one r~?nr~m r copolymerizable with the monomer Pl'.2.1, Pl'.2.3) from 0.1 to 25% by weight of a crosslinker component whose concen-tration increases f rom the inside to the outeide of the graf t layer and which comprises CY) from 0.1 to 100% by weight of dihydrodicyclopentadienyl acrylate and ~) from 0 to 99 . 996 by weight of at least one further crosslinker havingtwo or more functional groups of di f f erent reactivity and Pl'.2.4)from 0.1to 23~6 by weight of at least one crosslinker having two or more functional groups of the same reactivity, and P1'.3) from 0.1 to 99.8% by weight of at least one further segment at least cont~; n; ng a ~inyl-aromatic monomer, the sum of the percentages by weight of P1'.1 to P1'.3 and of P1'.1.1 to P1'.1.3 and P1'.2.1 to P1'.2.4 being 100% in each case.

A preferred embodiment of the no~el graft copolymer P1'' having a defined core-shell morphology contains Pl''.1) from 0.1 to 99.8% by weight of at least one grafting base comprising a hard segment having a glass transition temperature of at least 25~C
and a mean particle size (d50) of at least 50 nm, composed of P1''.1.1) from 50 to 99.8% by weight of at least one ~inylaromatic monomer, P1''.1.2) from 0 to 49.8% by weight of at least one ~?~mer copolymerizable with the mo~smer P1''.1.1, P1''.1.3) from 0.1 to 25% by weight of a crosslinker component increasing from the inside to the outside of the grafting base and comprising ~) from 0.1 to 100% by weight of dihydrodicyclopentadienyl acrylate and ~) from 0 to 99% by weight of at least one further crosslinker ha~ing two or more functional groups of different reacti~ity and Pli'.1.4) from 0.1 to 25% by weight of at lea~t Gne cros~linker having two or more functional groups of the same reacti~ity, ~P1''.2) from 0.1 to 99.8% by weight of at least one graft layer comprising a soft segment ha~ing a CA 02266467 l999-03-24 glas~ transition temperature of not more than 0~C, composed of P1''.2.1) from 50 to 100% by weight of at least one acrylate, P1''.2.2) from 0 to 50% by weight of at least one monomer copolymerizable with the monomer Pli'.2.1 and P1''.2.3) from 0 to 20% by weight of at least one crosslinker ~ or ~ or a mixture thereof, increasing from the inside to the outside of the graft layer, and P1''.3) from 0.1 to 99.8% by weight of at least one further segment at least cont~; n; ng a vinyl-aromatic monomer, the sum of the percentages by weight of P1''.1 to P1''.3 and P1''.1.1 to P1''.1.4 and P1''.2.1 to P1''.2.3 being 100% in each case.

A pre$erred embodiment of the novel graft copolymer P2' contains P2'.1) from 0.1 to 95% by weight of at least one grafting base comprising a soft segment having a glass transition temperature of not more than 0~C and a mean particle size (d50) of at least 50 nm, composed of P2'.1.1) from 50 to 100% by weight of at least one acrylate, P2'.1.2) from 0 to 50% by weight of at least one mo~omer copolymerizable with the monom~r P2~.1.1, and P2'.1.3) from 0 to 20% by weight of at least one crosslinker ~ or ~ or a mixture thereof whose concentration in-~ creases from the inside to the out-side of the grafting base, '' CA 02266467 1999-03-24 P2'.2) from 0.1 to 95% by weight of at least one graft layer comprising a hard segment having a glass transition temperature of at least 25~C, com-posed of P2'.2.1) from 50 to 99. 8% by weight of at least one vinylaromatic mQ~omer, P2'.2.2) from 0 to 49.8% by weight of at least one monQ~r copolymerizable with the mo~nmer P2'2.1, P2'.2.3) from 0.1 to 25% by weight of a crosslinker component whose concen-tration increases from the inside to the outside of the graft layer and which comprises a) from 0.1 to 100% by weight of dihydrodicyclopentadienyl acrylate and ~) from 0 to 99.9% by weight of at least one further crosslinker having two or more functional groups of different reactivity and P2'.2.4) from 0.1 to 25% by weight of at least one crosslinker having two or more functional groups of the same reactivity, ~2'.3) from 4. 7 yo 9 8. 7% by weight of a second graft layer comprising a soft segment having a glass transition temperature of not more than 0~C, compo8ed of P2'.3.1) from 50 to 100% by weight of at least one acrylate, P2'.3.2) from C to 50~ by weight of at least one monomer copolymerizable with mo~Qmer P2'.3.1) and P2'.3.3) from 0 to 20% by weight of at least one crosslinker a or ~ or a mixture thereof and P2'4) from 0.1 to 99.7% by weight of at least one further segment at least contA;n;ng a ~inyl-aromatic monomer, the sum of the percentages by weight of P2'.1 to P2'.4 and P2'.1.1 to P2'.1.3, P2'.2.1 to P2'.2.4 and P2'.3.1 to P2'.3.3 being 100% in each case.

B~ANPL~S

Testing of perfo-mAnce characteristics The weight average particle sizes (d50) were determined by means of an analytical ultracentrifuge according to the method described by W. Scholtan and H. Lange, Rolloid-Z. and Z.-Polymere 250 (1972), 782-796.

The ultracentrifuge measurement gi~es integral mass distribution of the particle diameter of a sample. From this it is possible to determine the percentage by weight of the particles which ha~e a diameter equal to or less than a certain size. The mean particle diameter, which is also referred to as the d50 value of the integral mass distribution, is defined as the value at which 50% by weight of the particles have a smaller diameter and 50%
by weight of the particles a larger diameter than the d50 value.

The notch impact strengths (ak [kJ/m2~) were measured at the stated temperatures according to ISO 179/leA, using stAn~Ard small bars which were injection molded and then milled (A notch).

Two ~ample series which have been produced at different processing temperatures were in~estigated in each case.
~he mean ~alue from the testing of 10 samples per 6ample series is stated in each case.

CA 02266467 l999-03-24 The viscosity numbers VN tcm3/g]) were deter~;ne~ in each case in a 0.5~ strength solution in dimethylformamide at 23~C. Insoluble gel components were removed by centri-fuging prior to the measurement, and the sample weight was appropriately corrected.

~E is a measure of colorability and was determined according to DIN 6174. The AE ~ralue was calculated from the difference between the opacities of 2 mm thick circular disks injection molded at 200~C over a white and a black background. If the difference AE thus determined is small, this means that the samples are difficult to color.

The gloss was determined according to DIN 67530 by a procedure in which light of certain intensity was direct-ed at the sample at an angle of incidence of 45~ and the intensity of the reflected light was measured by means of a photogoniometer.

The solids contents of the emulsion indicate the contentof all solids in percent by weight, based on the total mass of the respective emulsions.

A~ ~v~ations Polybutyl acrylate PBA
Polystyrene PS
Dihydrodicyclopentadienyl acrylate DCPA
n-Butanediol diacrylate BDA
Sodium salt of a C12-C10-paraffinsulfonic acid Na salt Potaxsium peroxodisulfate KPDS
Sodium pyrophosphate NaPP
Graft copolymer GCP
n-Butyl acrylate BA
Styrene S

Acrylonitrile AN
Seed latex SL
Core C
Graft layer GL

Preparation of the graft copolymers I1, I2 Preparation of the seed latex (ISLl) 4500 g of water, 30 g of the Na salt, 9 g of KPDS, 12 g of sodium bicarbonate and 1 g of NaPP were heated to 65~C
while stirring and under nitrogen, and 2940 g of S were added in the course of 3 hours. 60 g of DCPA were metered in in such a way that there was a linear increase in the metered amount of DCPA over 3 hours, simultaneous-ly with the metering of the S. After the end of the monomer addition, the emulsion was kept at 65~C for a further hour. The PS latex thus obtained had a mean particle diameter (d50) of 80 nm. The solids content of the PS emulsion was 39.9%.

PreParation of the seed latex (ISL2) for comParison The PS grafting base ISL2 was prepared similarly to ISLl, except that S and DCPA were metered in together in the course of 3 hours. The PS latex thus obtained had a mean particle diameter (dSo) of 83 nm. The solids content of the PS emulsion was 39.9%.

Preparation of the core (IlCl) 4200 g of water, 3 g of the Na salt, 1.75 g of ~PDS, 2.5 y of ~odium bicarbonate, 1 g of NaPP and 40 g of the emulsion prepared according to ISLl were heated to 65~C.
475 g of styrene and 15 g of BDA were then added in the i~course of 1 hour. 10 g of DCPA were metered in in such a way that there was a linear increase in the metered _ 59 amount of DCPA over 1 hour, simultaneously with the metering of styrene. After the end of the monomer addition, the emulsion was kept at 65~C for a further hour. The core comprising ISLl and IlCl had a mean particle diameter (d50) of 237 nm. The solids content of the emulsion was 8.7%.

PreParation of the core (IlC2) for comParison .

The graft layer IlC2 was prepared similarly to IlCl, except that styrene, DCPA and BDA were metered in to-gether in the course of 1 hour. The core comprising ISL2and IlC2 had a mean particle diameter (d50) of 241 nm.
The solids content of the emulsion was 8.8%.

PreParation of the PBA ~raft laYer (IlGLl) 20 g of the Na salt, 7.5 g of KPDS and 10 g of sodium bicarbonate and 2 g of NaPP were added to 4700 g of the emulsion prepared above (IlCl). At 65~C, 2459 g of BA
were added in the course of 3.5 hours. 50 g of DCPA were metered in in such a way that there was a linear increase in the metered amount of DCPA over 3 hours, simultaneous-ly with the metering of the BA. After the end of the mo~omer addition, stirring was continued for a further 2 hours at 65~C. The graft copolymer comprising ISL1, IlCl and IlGLl had a mean particle diameter (d50) of 443 nm.
The solids content of the emulsion was 38.8%.

PreParation of the qraft laYer (IlGL2) for comParison The second graft layer IlGL2 was prepared similarly to IlGL1, except that BA and DCPA were metered in toye~her in the course of 3.5 hours. The graft copolymer compris-ing ISL2, IlC2 and IlGL2 had a mean particle diameter ~(d50) of 450 nm. The solids content of the emulsion was 38.2%.

PreParation of the qraft laYer (I2GLl) 5000 g of the emulsion of the graft copolymer comprising ISLl, IlCl and IlGLl were diluted with 2400 g of water, and 5 g of the Na salt and 3. 5 g of RPDS were added. At 65~C, a mixture of 675 g of styrene and 225 g of AN was added dropwise in the course of 2 hours and stirring was carried out for a further 2 hours at 65~C. The graft copolymer comprising ISLl, IlCl, IlGLl and I2GLl had a mean particle diameter (d50) of 535 nm. The solids content of the emulsion was 39.3%.

Preparation of the qraft laYer (I2GL2) for comparison The third graft layer I2GL2 was applied to the graft copolymer consisting of ISL2, IlC2 and IlGL2 and prepared similarly to I2GLl. The graft copolymer comprising ISL2, IlC2, IlGL2 and I2GL2 had a mean particle diameter (d50) of 530 nm. The solids content of the emulsion was 39.5%.

Preparation of the qraft co~olYmers II1 and II2 The preparation of the segments of the graft copolymer~
II1 and II2 is shown in Table 1.

, .. . . . .

~ CA 02266467 1999-03-24 Preparation of the graft copolymers II1 and II2 ComponentPreparation as forMean particleSolids content diameter (d50) 1%
[nml IISLI ISLI 85 39.8 (S was replaced by BA) IISL2 ISL2 85 39.9 (cv~ a- ;SUII)(S was replaced by BA) IIIKI IIKI 240 8.8 IIIK2 IIK2 238 8.7 (comparison) IIIPAI IIPAI 435 38.9 III PA2 IIPA2 445 38.5 (Culll~l isOIl) II2PAI I2PA1 541 39.5 II2PA2 I2PA2 535 39.7 (comparison) s Blending experiments Graft copolymer Il (according to the invention) consists of:
ISLl, IlKl, IlPAl and I2PAl Graft copolymer I2 (comparison) consists of:
lO ISL2, IlK2, IlPA2 and I2PA2 Graft copolymer IIl (according to the invention) consists of:
IISLl, IIlKl, IIlPAl and II2PAl Graft copolymer II2 (comparison) consists of:
IISL2, IIlK2, IIlPA2 and II2PA2.

For the preparation of the blends, a styrene/

AMENDED SHEET

acrylonitrile copolymer ha~ing an acrylonitrile content of 34% and a viscosity number of 78 ml/g (the viscosity numbers were determined in a 0.5% strength solution in DMF at 23~C) was used as component III. The precipitated and dried graft copolymers I1, I2, II1 and II2 were blended with the component II in an extruder at 260~C.
This mixture was converted into shaped articles, for which the colorability ~E (color difference measurement according to DIN 6174 o~er white and black bachyLo~d) and the gloss (according to DIN 67530, using circular disks injection molded at a melt temperature of 250~C, at an angle of incidence of 45~) were determined. St~n~rd small bars were injection molded for deter~;n;ng the notched impact strength according to DIN 53453. The results are shown in Table 2.

.

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~ ENDED SHEET 1,

Claims (16)

We claim:-

1. A hard segment H1 having a glass transition temperature of at least 10°C, containing, as polymerized units, at least one vinylaromatic monomer as the monomer or as one of two or more monomers copolymerizable with one another and at least one crosslinker having two or more functional groups of different reactivity and at least one crosslinker having two or more functional groups of the same reactivity, the concentration of at least one crosslinker in the hard segment varying.

2. A hard segment H1 as claimed in claim 1, which comprises one or more of the following features:
a) that the concentration of at least one cross-linker having two or more functional groups of different reactivity, preferably dihydrodicyclopentadienyl acrylate, varies, but preferably increases, from the inside to the outside of the hard segment H1;
b) has a glass transition temperature of at least 25°C;
c) contains at least H1.1) from 50 go 99.8% by weight of at least one vinylaromatic monomer, H1.2) from 0 to 49.8% by weight of at least one monomer copolymerizable with monomer H1.1, H1.3) from 0.1 to 25% by weight of a cross-linker component comprising .alpha.) from 0.1 to 100% by weight of dihydrodicyclopentadienyl acrylate and .beta.) from 0 to 99.9% by weight of at least one further crosslinker having two or more functional groupe of different reactivity, the sum of the percentages by weight of .alpha.
and .beta. being 100, and H1.4) from 0.1 to 25% by-weight of at least one crosslinker having two or more functional groupe of the same reactivity, the sum of the percentagee by weight of H1.1 to H1.4 being 100.

3. A process for the preparation of a hard segment H1 as claimed in claim 1 or 2, wherein the variation in the concentration of at least one crosslinker ie effected by metering in the one or more crosslinkers.

4. A process as claimed in claim 3, wherein the variation, preferably increaee, in the concentration of at least one croeslinker having two or more functional groups of different reactivity, preferably a dihydrodicyclopentadienyl acrylate, is effected by metering in the at least one crosslinker.

5. A process ae claimed in either of claims 3 or 4, which is carried out as an emulsion polymerization in an aqueoue phase in the preeence of one or more emulsifiers and initiators at from 20 to 90°C.

6. Uee of a hard segment H1 as claimed in any of claims 1 to 4 for graft copolymers.

7. A graft copolymer P1 containing, in any desired sequence, at least one soft segment having a glass transition temperature of not more than 10°C, which contains at least one acrylate ae the monomer or as one of two or more monomers copolymerizable with one another and at least one crosslinker as polymerized units, and at least one hard segment H1 as claimed in any of claims 1 to 4.

8. A graft copolymer P1' as claimed in claim 7, which contains the soft segment as grafting base P1'.1 and the hard segment as graft layer P1'.2.

9. A graft copolymer P1'' as claimed in claim 7, which contains a hard segment as grafting base P1''.1 and the soft segment as graft layer P1''.2.

10. A graft copolymer P2, at least containing a graft copolymer as claimed in any of claims 7 to 9 and a further graft layer (P2.3) comprising a soft segment having a glass transition temperature of not more than 10°C, which contains at least one acrylate as the monomer or as one of two or more monomers copolymerizable with one another and at least one crosslinker.

11. A graft copolymer as claimed in any of claims 7 to 10, containing a further segment at least comprising a vinylaromatic monomer.

12. A process for the preparation of a graft copolymer as claimed in any of claims 7 to 11 by emulsion polymerization in an aqueous phase, wherein the variation in the concentration of at least one crosslinker is effected by metering in the one or more crosslinkers.

13. Use of at least one of the graft copolymers as claimed in any of claims 7 to 11 for thermoplastic materials.

14. A thermoplastic material (T1), at least containing T1.i) from 0.1 to 95% by weight of at least one of the graft copolymers P1 and P2, T1.ii) from 0 to 94.9% by weight of at least one graft copolymer differing from T1.i and/or a mixture thereof, T1.iii) from 5 to 99.9% by weight of at least one copolymer of T1.iii.1) from 50 to 100% by weight of at least one vinylaromatic monomer, C1-C18-alkyl acrylate, C1-C18-alkyl methacrylate or mixture thereof, and T1.iii.2) from 0 to 50% by weight of acrylonitrile, methacrylonitrile, maleic anhydride, N-substituted maleimides or a mixture thereof, the sum of the percentages by weight of T1.iii.1 and T1.iii.2 being 100, T1.iv) from 0 to 90% by weight of at least one polycarbonate and T1.v) from 0 to 50% by weight of additives, the sum of T1.i to T1.iv being 100.

15. A molding, film, fiber or coating, containing at least one of the graft copolymers as claimed in any of claims 7 to 11 and/or thermoplastic materials T1 as claimed in claim 14.

16. Use of one of the graft copolymers as claimed in any of claims 9 to 13 and/or thermoplastic materials T1 as claimed in claim 14 for moldings, films, fibers or coatings.