CA1087340A - Transparent polymer mixtures having high impact strength - Google Patents
Transparent polymer mixtures having high impact strengthInfo
- Publication number
- CA1087340A CA1087340A CA272,390A CA272390A CA1087340A CA 1087340 A CA1087340 A CA 1087340A CA 272390 A CA272390 A CA 272390A CA 1087340 A CA1087340 A CA 1087340A
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- Prior art keywords
- monovinyl
- weight
- aromatic compound
- star
- block copolymer
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L25/00—Compositions of, homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Compositions of derivatives of such polymers
- C08L25/02—Homopolymers or copolymers of hydrocarbons
- C08L25/04—Homopolymers or copolymers of styrene
- C08L25/06—Polystyrene
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L53/00—Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
- C08L53/02—Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers of vinyl-aromatic monomers and conjugated dienes
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- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Graft Or Block Polymers (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Manufacture Of Macromolecular Shaped Articles (AREA)
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Abstract
ABSTRACT OF THE DISCLOSURE: Mixtures of polystyrene and a block copolymer of a monovinyl-aromatic compound and a conjugated diene.
The mixture contains a thermoplastic, non-elastomeric block co-polymer having a star-shaped branched structure, the branches being of at least two types of different average composition, and at least 50% by weight of the monovinyl-aromatic compound being present as terminal polymer blocks in one or more of the branches.
The mixtures, which exhibit good transparency and high impact strength, are particularly suitable for the manufacture of moldings and packaging materials.
The mixture contains a thermoplastic, non-elastomeric block co-polymer having a star-shaped branched structure, the branches being of at least two types of different average composition, and at least 50% by weight of the monovinyl-aromatic compound being present as terminal polymer blocks in one or more of the branches.
The mixtures, which exhibit good transparency and high impact strength, are particularly suitable for the manufacture of moldings and packaging materials.
Description
1~)87340 .
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OOZo 31,895 TRANSPARENT POLYMER MIXTURES HAVING HIGH IMPACT STREN~TH
The present invention relates to mixtures of a polystyrene and a branched block copolymer of a monovinyl-aromatic compound and a conjugated diene, which exhibit good transparency and high impact strength. - ~-Polystyrene is a hard thermopiastic distinguished, in parti-cular, by its transparency. However, its brittleness and low ~ ;
impact strength are disadvantages in numerous applications~
It is known to improve the mechanical properties of poly~styrene, especially its impact strength, by modification with rubber~ materials, either by mixing the rubber with the polystyrene or by polymerizing styrene in the presence of the rubberO The rubbery materials used to improve the impact strength are, in par-~.
ticular, homopolymers and copolymers of oonjugated dienes, eOg~
polymers of butadiene or isoprene. Particularly advantageous pro-ducts, in respect of their mechanical properties, are obtained ~` by employing elastomoric block copolymers of styrene and a con-jugated dieneO These compri~e~a predominant proportion of the con-jugated diene and a minor proportion of styrene and may have a linear or star-shaped branched structureO
However 9 when rubbery materials are incorporated into poly-styrene, the transparency of the latter is destroyed, so that the ~ --1--,.
- 1 0 ~3 4 0 OOZ~ 313895 styrene polymers of improved impact strength9 thus obtained, are unsuitable for many applications, for example in the packag;ng sectorO
It has also been disclosed that styrene polymers having high impact strength and good mechanical properties may be obtained by manufacturing non elastomeric block copolymers of styrene and a conjugated diene, comprising a predominant proport;on of the ~ormer and a lesser propsrtion of the latterO For example, ~erman Laid-Open Application DOS 1,959,922 discloses branched block copolymers 10 having a star-shaped structure, comprising a predominant proportion ~:
of styrene and a lesser proportion of a conJugated diene, which - :
exhibit, at one and the same time, good impact strength, clarity, ~ :
good processability and extreme stabilityO These branched block copolymers are obtained by coupling styrene-diene two-block copoly- -~
mers in which the terminal polystyrene blocks are of varying lengths.
It is true that these products exhibit a pattern of properties which is satisfactory in many respects and are both impact-resistant and transparent; however, becaùsè of the involved process of manufacture they are comparatively expensiveO~
It is an object of the present invention to improve the mechanical properties of polystyrene, whilst retaining its trans-parency, by an economical method which in particular gives products having good impact strength which are, at the same time, substan-tially glass-clear and readily processableO
We have found that this o~ject is achieved, according to -~he invention, by blending polystyrene with a non elastomeric, star- -shaped block copolymer of a monovinyl-aromatic compound and a con-jugated diene, the non-elastomeric star-shaped block copolymer having a specific structureO
Accordingly, the present invention relates to mixtures com-prising essentially A) from 10 to 70 per cent by weight of polystyrene and ~B) from 90 to 30 per cent by weight of a thermoplastic star-
.. ;,: ~
`.
OOZo 31,895 TRANSPARENT POLYMER MIXTURES HAVING HIGH IMPACT STREN~TH
The present invention relates to mixtures of a polystyrene and a branched block copolymer of a monovinyl-aromatic compound and a conjugated diene, which exhibit good transparency and high impact strength. - ~-Polystyrene is a hard thermopiastic distinguished, in parti-cular, by its transparency. However, its brittleness and low ~ ;
impact strength are disadvantages in numerous applications~
It is known to improve the mechanical properties of poly~styrene, especially its impact strength, by modification with rubber~ materials, either by mixing the rubber with the polystyrene or by polymerizing styrene in the presence of the rubberO The rubbery materials used to improve the impact strength are, in par-~.
ticular, homopolymers and copolymers of oonjugated dienes, eOg~
polymers of butadiene or isoprene. Particularly advantageous pro-ducts, in respect of their mechanical properties, are obtained ~` by employing elastomoric block copolymers of styrene and a con-jugated dieneO These compri~e~a predominant proportion of the con-jugated diene and a minor proportion of styrene and may have a linear or star-shaped branched structureO
However 9 when rubbery materials are incorporated into poly-styrene, the transparency of the latter is destroyed, so that the ~ --1--,.
- 1 0 ~3 4 0 OOZ~ 313895 styrene polymers of improved impact strength9 thus obtained, are unsuitable for many applications, for example in the packag;ng sectorO
It has also been disclosed that styrene polymers having high impact strength and good mechanical properties may be obtained by manufacturing non elastomeric block copolymers of styrene and a conjugated diene, comprising a predominant proport;on of the ~ormer and a lesser propsrtion of the latterO For example, ~erman Laid-Open Application DOS 1,959,922 discloses branched block copolymers 10 having a star-shaped structure, comprising a predominant proportion ~:
of styrene and a lesser proportion of a conJugated diene, which - :
exhibit, at one and the same time, good impact strength, clarity, ~ :
good processability and extreme stabilityO These branched block copolymers are obtained by coupling styrene-diene two-block copoly- -~
mers in which the terminal polystyrene blocks are of varying lengths.
It is true that these products exhibit a pattern of properties which is satisfactory in many respects and are both impact-resistant and transparent; however, becaùsè of the involved process of manufacture they are comparatively expensiveO~
It is an object of the present invention to improve the mechanical properties of polystyrene, whilst retaining its trans-parency, by an economical method which in particular gives products having good impact strength which are, at the same time, substan-tially glass-clear and readily processableO
We have found that this o~ject is achieved, according to -~he invention, by blending polystyrene with a non elastomeric, star- -shaped block copolymer of a monovinyl-aromatic compound and a con-jugated diene, the non-elastomeric star-shaped block copolymer having a specific structureO
Accordingly, the present invention relates to mixtures com-prising essentially A) from 10 to 70 per cent by weight of polystyrene and ~B) from 90 to 30 per cent by weight of a thermoplastic star-
-2-1~7340 OOZo 31~ 895 shaped block copolymer of a monovinyl-aromatic compound and a conjugated diene, wherein component B is a non-elastomericg star=shaped block co-polymer which comprises from 60 to 95 per cent by weight of the monovinyl-aromatic compound and from 40 to 5 per cent by weight of a conjugated diene and which possesses at least two types, of different average composition, of copolymer blocks which ~orm the branches, at least 50 per cent by weight of the total monovinyl-aromatic compound present as copolymerized units in the star-shaped block copolymer being contained therein, as blocks 3 in the terminal polymer segment of one or more of the copolymer blocks of the branchesO
Though polystyrene and non-elastomeric, star-shaped block co-polymers comprisin~ a predominant proportion of a monovinyl-aromatic compound and a minor proportion of a conjugated diene are inherently transparent products, it was extremely surprising that the trans-parency was retained on blending the two components in accordance with the present invention, since the refractive indices of the two components are distinctly different and the known blends of polystyrene with branched block copolymers, having an elastomeric character, of a monovinyl-aromatic compound and a conjugated diene give significantly turb;d or even opaque productsO It is to be assumed that the tranæparency of the mixtures according to the invention is due to compatibility of the two components, and such compatibility is extremely rarely observed in polymer mixturesO
The polystyrene to be employed as eomponent A of the mixtures according to the invention may be manu~actured in the conventional manner by mass polymerization, solution polymerization or aqueous dispersion polymerization of styrene~ Preferably, a polystyrene obtained by mass polymerization or solution polymerization is employed; this material is conventional amorphous polystyreneO-The viscosity-avera~e molecular weight of the polystyrene is in ~eneral from 50,000 to 1,000,000, preferably from 100~000 to
Though polystyrene and non-elastomeric, star-shaped block co-polymers comprisin~ a predominant proportion of a monovinyl-aromatic compound and a minor proportion of a conjugated diene are inherently transparent products, it was extremely surprising that the trans-parency was retained on blending the two components in accordance with the present invention, since the refractive indices of the two components are distinctly different and the known blends of polystyrene with branched block copolymers, having an elastomeric character, of a monovinyl-aromatic compound and a conjugated diene give significantly turb;d or even opaque productsO It is to be assumed that the tranæparency of the mixtures according to the invention is due to compatibility of the two components, and such compatibility is extremely rarely observed in polymer mixturesO
The polystyrene to be employed as eomponent A of the mixtures according to the invention may be manu~actured in the conventional manner by mass polymerization, solution polymerization or aqueous dispersion polymerization of styrene~ Preferably, a polystyrene obtained by mass polymerization or solution polymerization is employed; this material is conventional amorphous polystyreneO-The viscosity-avera~e molecular weight of the polystyrene is in ~eneral from 50,000 to 1,000,000, preferably from 100~000 to
-3-101!~7340 o o z o 31 3 895 500~000O The mixtures contain from 10 to 70 per cent by weight ofpolystyrene~ based on the sum of the components A and Bo Component B of the mixtures according to the invention, employed in amounts of from 90 to 30 per cent by weight, based on the sum of A and B, is a non-elastomeric, star-shaped block copolymer comprising a predominant proportion of a monovinyl- ~:
aromatic compound and a minor proportion of a conjugated dieneO
Examples of monovinyl-aromatic compounds which may be used to synthesize the branched block copolymers are styrene, styrenes 10 with alkyl side-chains, e~gO o~-methylstyrene, and nuclear-substi- ~:
tuted styrenes, eOgO vinyltoluene or ethylvinylbenzene~ The mono-vinyl-aromatic compounds may be employed individually or as mix-tures with one anotherO However, the use of styrene alone is pre-ferredO The conjugated dienes employed are in general of ~ to 8 carbon atomsO Examples of conjugated dienes which may be employed, individually or as mixtures with one another, for the manufacture of the branched block copolymers are butadiene, isoprene and 2,3-dimethyl-butadieneO Butadiene and isoprene give particularly advantageous results, and of the two, butadiene is preferred~
The branched block copolymers of the mixtures according to the invention should contain a total of from 60 to 95 per cent-by weight, especially from 70 to 90 per cent by weight, of the mono- .
vinyl-aromatic compound and from 40 to 5 per cent by weight, pre-ferably from 30 to 10 per cent by weight, of the conjugated diene, in each case based on total monomers employed, as copolymerized unitsO The molecular weight of the branched block copolymers is as a rule from 100,000 to 1,000,000 and preferably from 150,000 to 500,000~ These data relate to the weight-average molecular weight, determined by viscosity measurements on an 005 per cent strength by weight toluene solution at 25C~
The starshaped branched block copolymers to be employed according to the invention have branches consisting of copolymer blocks in which the monovinyl-aromatic compound and the conJugated ~0~7340 oO z o 31~895 diene units are present as blocks, forming individual polymer seg-mentsO These copolymer blocks) themselYes of block structure, which form the branches, are chemically coupled to one another by means of a coupling agentO The star-shaped block copolymers have at least 3, in general from 3 to 10, and preferably 3 or 4, such branches, and these branches should comprise at least two types of copolymer blocks of different average composition~ Furthermore, at least 50 per cent by weight, preferably at least 60 per cent by weight, of all the monovinyl-aromatic compound present as copolymerized units in the star-shaped block copolymer should be contained in the ; terminal homopolymer segment of one or more of the copolymer blocks of the branchesO
The preferred component B of the mixtures of the invention is a star-shaped block copolymer, the most probable average structure of which is represented by one of the ~eneral formulae (I), (II) or (III) below:
(I) (A-B)k-X , (II) (Al_B1 ~ A2)n-X-(A2 ~---- B )m (III) (A3-A4-B2 __~ A5) -X-(A5 ~ B2~A )m ~
In these general formulae (I) - (III), A and A1-A5 are non-elastomeric polymer segments of the mono~inyl-aromatic com-pound, of which the polymer segments A in the polymer (I) should have a polymodal, preferably bimodal, molecular weight distribu-; tion, whilst the individual polymer segments Al-A5 in the poly-mers ~II) and (III) should each have a unimodal molecular weight distribution, B, B and B are elastomeric polymer segments based on the conjugated diene, X is a radical of a polyfunctional cou~ling agent by means of which the copolymer blocks forming the branches are chemically coupled to one another, k is an integer not less ; 30 than 3, in general from 3 to 10 and preferably 3 or 4 and m and n are numbers, m being equal to or greater than n and the sum of m ~7340 o~ z o 31,895 and n bein~ at least 3, in ~eneral an integer from 3 to 10 and preferably 3 or 40 ~.
The symbol ~ in the general formulae (II) and (III) means that the transition between the polymer segments concerned is gradual rather than sharpO
Star-shaped block copolymers of the general formula (A-B)k X (I) have already been dislcosed in German Laid-Open Application DOS 1,959,9220 In these, the non-elastomeric polymer se~ment A is, in particular, a homopolystyrene segment~ The mole-1~ cular weight and polymodality depend pr;mar;ly on the intendedapplication of the end productO As explained in more detail below, the molecular weight is decided by the amount o~ initiator employed per mole of monomer in the manuracturing process; the polymodality depends on the number of times that initiator is added dur;ng the polymerization and is preferably 2 or 3 and espec;ally 2~ The elastomeric polymèr sègment B based on the conjugated dienes is preferably a homopolydiene segment, especially a homopolybutadiene or a homopolyisoprene segment. It may however also contain small amounts, of up to about 30 per cent by weight, preferably of less than 20 per cent by weight, based on polymer segment B, of other copolymerizable monomers, especially of styrene, as copolymerized unitsO
In the star-shaped branched block copolymers which have the most probable average structure of the general formula (II) (A1-B~ A2)n-X-(A2 ~--- B1)m the non-elastomeric polymer segment A1 advantageously contains, as copolymerized units, from 50 to 80 per cent by weight, prefer- ;
ably from 60 to 78 per cent by wei~ht, of the total monovinyl-aromatic compound employed for the manufacture of the branched block copolymer, and is, in particular, a homopolystyren~ segment.
~ Its molecular weight depends primarily on the-application envisaged : for the end product and is preferably from 50,000 to 250,0000 1~7340 O~Z0 31,895 The elastomeric polymer segmtnt B1 is a copolymer block comprising essentially the conjugated diene and a minor proportion of monovinyl-aromatic compound, the distribution of the monomers being sub-stantially randomO The proportion of the monovinyl-aromatic com-pound in the polymer segment B1 is in general less than about 30 per cent by weight and especially less than abcut 20 per cent by weight, based on the amount of monovinyl-aromatic compound of the branched block copolymer not in the form of un;ts o~ the polymer segment A1D The transition between the polymer segments A1 and B1 is sharp, whilst the transition between the polymer segments B1 and A2 is gradual in the sen-e that the proportion of the monovinyl-aromatic compound in the polymer segment B1 increases progressively in the direction of the polymer segment A2 and the proportion Or the conjugated diene accordingly decreases progressivelyO The non-elastomeric polymer segments A2 are, like the polymer segment A1, pref~rably homopolystyrene segments7 The molecular weight o~ the polymer blocks (B1 - A2) is preferably from 10,000 to 100,000.
In the star-shaped branched block copolymers which have most probable average structure of the general formula (III) (A3-A4-B2 ~ A5)n-X-(A5 ~-- B2-A4)m the non-elastomeric polymer segment A3 advantageously contains, as copolymerized units, from 50 to 80 per cent by weight, prefer-; ably from 60 to 75 per cent by weight, of the total monovinyl-aromatic compound employed for the manuracture of the branched block copolymer, and is, in particular, a homopolystyrene segmentO i Its molecular weight is preferably from 509000 to 250,0000 The polymer segments A4 correspond to the polymer segments A3 except that they have a lower molecular weight, usually from 5,000 to 50,0000 They contain, as copolymerized un;ts, from 1 to 30 per cent 3 by weight, preferably from 5 to 25 per cent by weight, of the total monovinyl-aromatic compound, but the sum of the monovinyl-aromatic compound copolymerized in the polymer segments A3 and A4 should ~0~7340 oOz~ 319895 not exceed 90 per cent by weight of the total amount of monovinyl-aromatic compound employed for the manufacture of the branched block copolymersO The elastomeric polymer segment B2 is a copolymer block comprising ess~ntially the conjugated d;ene with a minor proportion of monovinyl-aromatic compound, the distribution of the :~
monomers being substantially randomO The proportion o~ the mono-vinyl-aromatic compound in the polymer segment B2 is in general less than about 30 per cent by weight and especially less than about 20 per cent by weight, based on the amount of monovinyl-aromatic compound not present as units in the polymer segments A3 and A40 The transition between the polymer segments A4 and B2 is sharp, whilst the transition between the polymer segments B2 and A5 is gradual~ The non elastomeric polymer segments A5 are, like the polymer segments A3 and A4, preferably homopolystyrene segments.
The molecular weight of the polymer blocks (A3_A4_B2 _-~ A5) is preferably from 100,000 to 500,000 whilst that of the polymer blocks (A4_B2 > A5) is from 10,000 to lOO~OOOo According to a preferred embodiment of the invention, non-~- elastomeric, star-shaped block copolymers in which the content of - 20 olefinic double bonds has been reduced by selective hydrogenation to less than 5%, preferably less than 2%, are employed as the com-ponent Bo Where selectively hydrogenated derivatives of star shaped branch~d block copolymers of the general formula (I), in which the polymer segment B, prior to hydrogenation, is a polybutadiene seg-ment, are employed, it is necessary to ensure that this polybuta-diene se ment has a 1,2-vinyl content of from 10 to 50 per cent by weight and that after hydrogenation the polymer segment B has a crystallinity of less than 5%, preferably of less than 2% 9 if products having the desired properties are to be obtained~ The 30 crystallinity of the hydrogenated polymer segments B is determined ~.
by differential calorimetry using a Perkin-Elmer DSC calorimeterO
The special composition, and the structure, of the star-shaped branched block copolymers df-pend on, and are determined by, the ` 10~7340 oOzO 31~895 conditions chosen for the polymerization of the monomersO In general, the non elastomeric, star~shaped block copolymers suitable for use :
as component B in the mixtures of the invention are manufactured by successive polymeriza~ion of the monomers ;n solution ;n the presence of a monolithium-hydrocarbon as the initiator, with step-wise addition of monomer and initiator and subsequent coupling of the resulting living linear block copolymers with a polyfunctional reactive compound as the coupling agentO
The initiators used are the conventional mono lithi~m-hydro- :
carbons of the general formula RLi, where R is an aliphatic, cyclo-aliphatic, aromatic or mixed aliphatic-aromatic hydrocarbon radical.
The latter may be of 1 to about 12 carbon atomsO The following may be mentioned as examples of suitable lithium~hydrocarbon initiators:
methyl-lithium, ethyl-lithium, n , secO- and tertO-butyl-lithium, isopropyl-lithium, cyclohexyl-lithium, phenyl lithium and p-tolyl-lithiumO The use of monolithium-alkyl compounds, where alkyl is of 2 to 6 carbon atoms, is preferred, n-butyl-lithium and secO-butyl-lithium being particularly preferredD
The polymerization of the monomers is carried out in solution in an inert organic hydrocarbon solventO Suitable hydrocarbon solvents are aliphatic, cycloaliphatic or aromatic hydrocarbons which are liquid under the reaction conditions and which are pre-ferably of 4 to 12 carbon atomsO Examples Or suitable solvents are isobutane, n pentane, isooctane, cyclopentane, cyclohexane, cyclo-heptane, benzene, toluene, the xylenes, and the likeO Mixtures of these solvents may also be employed, Furthermore, the polymerization can be carried out in the presence of small amounts 3 ;n general from 10 3 to 5 per cent by weight, based on the total colvent, of ethers, e DgO tetrahydrofuran, dimetho~yethane and anisole, thereby 3o influencing, ;n the conventional manner, the rate of polymerization, the configuration of the diene polymer segments and the random transition between the segment B1 and A2, or B2 and A5, in the products of the general formula (II) and (III), respectivelyO
_g_ 1~87340 O~Z~ 319895 The concentration of the monomers in the reaction solution is not critical and can be so chosen that any desired apparatus can be used for the polymerizationO In general, the polymerization is carried out in a solution of from 10 to 30 per cent strength in the inert solvents The polymerization is carried out under the conventional con-ditions for anionic polymerization with lithium-organic compounds, for example in an inert gas atmosphere, with exclusion of air and moistureO The polymerization temperature may be from 0 to 120C
and is preferably kept at from 40 to 80Co The polyfunctional coupling agent used for the coupling reaction carried out after the polymerization should be at least tri~unctional, i.e. it should be capable of reacting with at least three of the active, linear block copolymer chains formed, at their terminal lithium-carbon bonds, to form a chemical bond, so that a single, coupled and accordingly branched block copolymer is formedO The coupling of lithium-terminated living polymers with polyfunctional coupling agents is known in the art and is disclosed, for example, in British Patent 985,6140 Examples of suitable coup-iing agents for the manufacture of the star-shaped block copolymers to be employed according to the invention are polyepoxides, e.g.
epoxidized linseed oil, polyisocyanates, eOgv benzo-1,2,4-triiso- ~-cyanate, polyketones, eO~0 1,3,6-hexanetrione or 1,4,9,10-anthra-cenetetrone, polyanhydrides, eOgO pyromellitic dianhydride, or polyhalidesO Dicarboxylic acid esters, eOgO diethyl adipate or the like, may also be used as coupling agentsO A further preferred group of coupling agents comprises the silicon halides, especially `-silicon tetrachloride, silicon tetrabromide, trichloroethylsilane and 1,2-bis-(methyldichlorosilite)-ethaneO Polyvinyl-aromatics, 0 especially divinylbenzene, may also be used as coupling agents, as disclosed, for example, in UOSo Patent 3,280,0840 In that case, a few divinylbenzene units undergo addition with crosslinking; to form a branching center, by means of which the preformed polymer blocks are bonded to one anot~grO
10~7340 oOzO 31,895 The nature of the polyfunctional coupling agent employed is not critical, provided it does not significantly impair th~ desired properties of the end productO The use of a tri~unctional or tetra-functional coupling agent of the type described3 or o~ divinyl-benzene, is preferredO In general9 the poly~unctional coupling .
agent is added to the reaction solution in amounts equivalent to the total amount of the living polymer blocks, iOe~ equivalent to the number o~ the active lithium-carbon bonds in the previously formed linear copolymer blocksO The reaction Or the living, linear block copolymers with the coupling agent is preferably carried out under the same reaction conditions as the preceding polymerization of the monomersO
Specifically, the non-elastomeric, star-shaped block copoly-mers to be employed in the mixtures o~ the invention are manufactured as follows: in a ~irst processsta~e, a substantial part of the total amount of monovinyl-aromatic compound, in general from 50 to 80 per cent by weight and in particular from 60 to 75 per cent by weight of the total amount of monovinyl-aromatic compound employed for the manufacture of the star-shaped block copolymers, i8 poly-20 merized by means o~ a relatively small amount of the monolithium- :
hydrocarbon initiator until the monovinyl-aromatic compound employed has been completely convertedO The amount of initiator employed in the first process sta~e depends above all on the desired molecular weight of the polymer and is in general from Ool to 5 mmole~ per mole o~ the monovinyl-aromatic compounds employed in this first process stageO Preferably? the polymerization in the first process stage is carried out with from 0~4 to 2~5 mmoles of initiator per mole of the monovinyl-aromatic compounds employed in thls stage~ :
This gives a solution o~ non elastomeric, living polymers of the monovinyl-aromatic compound, with active terminal lithium-carbon bonds, to which further monom~rs can addO In a second process stage~
the remaining monomers are added, all at once or in several successive - stages, to the above reaction solution, after addition of a further ~o~7340 oOzO 31,895 amount of init;ator~ which should be as great or greater than the original amounts of initiator employed ln the first process stage of the polymerizationO Preferably, the amount of fresh ;nitiator added in the second process sta~e is from 1 to 15 times, and especially from 1 to 10 times, the amount of initiator originally employed. It is particularly advantageo~s if this factor ls rrom 1 to 5, especially if trifunctional or tetrafunctional coupling a~ents are employed in the subsequent coupling reaction~ Preferably, the initiator used is the same as in the flrst process stageO It is advanta~eous to introduce the additional fresh initiator into the reaction solution before adding the remaining monomersO
The composition and structure of the resulting block copolymers can be decided, and varied, by varying the manner in which the :
remaining monomers, iOeO both the remaining portion o~ the mono-vinyl-aromatic compound and the conjugated diene, are added to the reaction solution produced in the first process ~tage. For example, the remaining portion of the monovinyl-aromatic compound and the conjugated diene can be added in a single stage, as a mixture;
they can however also be added in several successive stages, for example by separately adding first the remaining portion of the monovinyl-aromatic compound and then the conjugated diene, or first a further partial amount of the monovinyl-aromatic compound and then a mixture of the remaining portion of the monovinyl-aromatic compound and the conjugated diene~ A~ter each fresh addition of monomers in the second process stage, the polymerization is taken to complete conversion of the added monomers before adding further monomer or before ultimately adding the coupling agent If appropriate, further additional amounts of initiator may also be employed repeatedly in the second process stage To produce star-shaped block copolymers of the general formula (I) (A-B)k-X which have a polymodal distxibution in the non-elastomeric polymer segments A formed from the monovinyl-aromatic compounds, the procedure followed is9 for example, first to add ~37340 OOZo 319895 the remaining monovinyl-aromat;c compound, iOeO ~rom 20 to 50 per cent by we;ght, preferably from 25 to 40 per cent by weight9 of the total monovinylaromatic compound employed for the manufacture of the branched block copolymerg in one or more port;ons to the reaction solution manufactured in the first process stage, each addition of a portion of the monovinylaromatic compound being accompanied by the addition Or a further amount of initiator which is as great or greater than the original amount of initiator employed in the rirst process stage of the polymerizationO Though it is possible to add the remaining portion of the monovinyl aromatic compound in as many portions as desired ~o the reaction solution in the course of the second process stage, it ;s pre- -ferred to add the remaining monovinyl-aromatic compound to the polymerization solution in 1 or 2 portions in the course o~ the said process stage, the addition ;n one portion having proved particularly advantageousO The monovinyl-aromatic compounds added in the second process stage undergo addition at the active, lithium-terminated chain ends of the previously formed polymers and also form new chains of living polymers whenever rresh ini-tiator is also addedO Accordingly, after complete polymerization of the remaining monovinyl-aromatic compound, the solution obtained contains polymers of the monovinyl-aromatic compound with difrerent average chain lengths, i~eO the non-elastomeric polymer segements A rormed from the monovinyl aromatic compounds have a polymodal distribution, with the polymodality of the polymer segments A
corresponding to the total number of additions o~ initiator and monomerO Therearter, in a second step, the total amount o~ the conjugated diene i8 added and polymerized to complete conversion.
In the course thereof, the conJugated diene undergoes addition at the active, lithium-terminated chain ends of the previously ~ormed polymodal, non elastomeric polymer segments A to form the elasto-meric polymer segments B, so that the reaction solution contains the copolymer blocks (A-B) which form the branches and which -13~
J~0~73~0 o o z o 31 9 895 possess an active reactive lithium~carbon bond at the ~ree end of the elastomeric diene polymer segment B; these blocks are sub-sequently coupledO
To manufacture star-shaped branched block copolymers of the general formula (II) (Al-Bl ~ A2)n X~(A2 ~ Bl)m the procedure followed in the second process stage o~ the poly-merization is to add, to the fully polymerized reaction solution from the first process stage, first an additional amount of initiator and then a mdxture of the remaining monovinyl aromatic compound and the total amount of the conjugated diene, and to polymerize the mixtureO In the course thereo~, the monomers added in the second process stage undergo addition at the active, living chain ends of the previously formed polymer segments A1, and also form new chains of living polymers, as a result of the fresh initiator addedO Because of the different copolymerization para-meters, the conjugated dienes polymerize substantially more rapidly than the monovinyl-aromatic compounds so that, after addition of the monomer mixture in the second process stage, it is first predominantly the conjugated dienes which undergo polymerization, and only occasionally are units of the monovinyl aromatic compounds copolymerized. Only toward the end of the diene polymerization, iOe. when almost all the conjugated diene has polymerized, does the polymerization of the monovinyl-aromatic compounds commence to a significant degree, so that the predominant proportion ~ as a rule more than 70 per cent by weight, and in most case~ more than 80 per cent by weight - of khe monovinyl aromatic compounds contained in the monomer mixture only polymerizes after the con-jugated dienes have been consumedO Accordinglyg in this case, the second process stage first results in the formation of the elastomeric polymer segment B , based on the conjugated diene, this segment being a copolymer segment mainly comprising the con-~)8 7340 0 Z0 31,895jugated diene, w;th small amounts of the monovinyl aromatlc compound, after which the non-elastomeric polymer segment A~ is ~ormed~ wh;ch is made up of the monovinyl-aromatic compound onlyO S;nce ~he pro~
portion of the monovinyl-aromatic compound progressively increases toward the end of the polymer segment B1 and the proportion of the conjugated diene accordingly progressi~ely decreases~ the transition between the polymer segments B1 and A2 thus formed is not s~arp and instead occurs gradually; this is therefore also frequently described as a blurred tran~ition between the segmentsO After com plete polymerization of the monomer mixture in the second process stage, the reaction solution thus contains a mixture of the linear block copolymers of the type (A1~B1 --j A2~ and (B~ A2)9 with active reactive lithium-carbon bonds in each case at the free end of the polymer segments A29 from which block copolymers the branches are formedO The ratio of the two types of block copolymers in the reaction solution corresponds to the initiator ratio in the first and second process stagesO The mixture of these two types of block copolymers is then coupled, by adding a polyfunctional .
reactive compound, to act as the coupling agent, to the reaction 20 solution.
To manu~acture star-shaped branched block copolymers of the general ~ormula (III) (A3_A4_B2 ~_~ A5~ X~(A5 ~ B2 A4) the procedure ~ollowed in the second process stage of the poly-merization is to add9 to the completely polymeriæed reaction solution from the first process stage~ first a further amount of ;nitiator ~nd then a further 1 30 per cent by weight, preferably 5 - 25 per cent by weight, of the total amount of the monovinyl-aromatic com-pounds used overall for the manufacture of the branched block co-polymersO The sum of the amount of monovinyl-aromatic compound employed in the first and second process stage should however be at most 90 per cent by weight of the total amount of the monovinyl-.. . . .. . .
3~ 0 OOZo 313~95 aromatic compound whîch is employed for the m~nu~actura of the branched block copolymersO The monovinyl aroma~1c compounds added undergo addition at the act;ve, lithium~termînated chain ends of the polymer segments A3 t formed be~orehand in the first process stage, so as now to form the polymer segments A4 a and also ~orm new chains of living polymers of the mono~inyi~aromatic compound as a result of the fresh initiator addedO After complete polymeri-zation of the monovinyl-aromatic compound initially added in the second process stage, the solution obta;ned thus contains living polymers of the monovinyl-aromatic compound with two different average chain lengths, namely, on the one hand9 active liv;ng polymer segments of type (A3-A4~ 9 which have been ~ormed by addition of the monovinyl-aromatic compound, first added in the second pro-cess stage, onto the active livin~ polymer segments A3 formed be-forehand in the first process stage, and, on the other hand9 active living polymer segments of type A4, which have been ~ormed by poly-merization o~ the monovinyl-aromatic compound, ~irst added in the second process stage, with the rresh initiator init;ally introducedO
The ratio in which these two types of non-elastomeric polymer segments based on the monovinyl-aromatic compounds are present in the reaction solution accordingly corresponds to the initiator ratio of the ~irst and second process stagesO Both types o~ polymer :~ segments, (A3 A4) and A4, have active, reactive lithium carbon bonds, capable of undergoing addition of ~urther monomers, at one chain endD A monomer mixture of the remaining monovinyloaromatic compound and the total amount of the conjugated diene is then added to this reaction solution and polymerized until the monomers are virtually completely converted~ As described above~ the polymeri-zation of the monomer mixture comprising the remainin~ monovinyl-aromatic compound and the conJugated d;ene results~ because o~
the different copolymerization parameters of the monomers, rirst in the formation of the elastomeric polymer segment B2 based on the conjugated diene, which segment is a copolymer comprising ~09~7340 O d Z 0 3~,895 mainly the conjugated diene with small amounts of the monovlnyl-aromatic compound, and thereafter in a nonelas~omeric polymer segment A5 which comprises only the monovinyl~aromatic compounds~
Since the monovinyl-aromatic compound is thus copolymerized to a progressively greater degree toward the end of the polymer segment B and the proportion of the conjugated diene accordingly progres-sively decreases, the transition between the polymer segments B2 and A5 which are formed is not sharp but gradualO After complete polymerization of the monomer mixture comprising the remainlng monovinyl-aromatic compound and the conjugated diene, the reaction solution contains a mixture of the linear block copolymers of type (A3-A4-B2 ~ A5) and (A4-B2 ~ A5), having active, reactive lithium;carbon bonds in each case at the free end of the polymer segments A5, which block copolymers form the branches and are subsequently coupled to produce the star-shaped block copolymerO
The branched block copolymers obtained are isolated from the reaction solution in the conventional manner, for example by pre~
cipitating the polymer from the reaction solution and filtering offO
Following the coupling reaction and advantageously prior to isolating the reaction product from the reaction solution, the olefinic double bonds of the branched block copolymers obtained may be subjected to selective hydrogenationO The latter may be carried out in the conventional manner, using molecular hydrogen and catalysts based on metals, or salts of metals, of group 8 of the periodic table, as described, for example, ;n UOSo Patent 3,1~3,986, German Published Application ~AS 1,222,260, German Laid-; Open Application DOS 2,013,263 or UOSo Patent 3,70096330 Accordlng to these publications, the selective hydrogenation of the olefinic double bonds of the branched block copolymer is preferably carried out in a homogeneous phase, using catalysts based on salts,especially carboxylates, enolates or alkoxides, of nickel~ cobalt or iron, which have been reduced with metal alkyls, e~pecially aluminum-alkyls, at hydrogen pressures of from 1 to ~00 bars and ~7340 03Zo 319895 at from 25 to 150Co me selective hydrogenation is continued until the content of olefinic double bonds in the branched block copoly mer has been reduced to less than 5% and pre~erably less than 2%~
This res;dual content is determined by a Wij~ titration or by analysis by IR spectroscopyO In particular, the hydrogenation is continued until the olefinic double bonds have been reduced vir~
tually completelyO Preferably, the hydrogenation is carried out under conditions such that the aromatic double bonds of the branched block copolymer are not attacked at the same timeO
Components A and B of the mixtures of the invention can be homogeneously mixed with one another in the conventional manner using known methods, ~or example by mixing in the melt, using suitable mixing equipment, eOgO kneaders, internal mixers or extrudersO The mixtures may in addition contain the conventional additives for polystyrene, eOgO antistatic agents, stabilizers and the like.
The mixtures of the invention exhibit good transparency and clarity, like polystyrene itself~ The proportion o~ light scattered on passage through a film or sheet serves as a measure of the transparency and clarity. Compared to polystyrene, the mixtures of the invention exhibit substantially improved mechanical proper-ties, and in particular improved impact strength and notched impact strengthO Compared to the non-elastomeric, star-shaped branched block copolymers disclosed in German Laid-Open Application DOS
1,959,922, the mixtures of the invention are cheaper without en-tailing a significant decrease in impact strength and notched impact strength, even if the proportion of polystyrene is relatively higho The mixtures of the invention may be processed easily by conventional methods used for thermoplastics, eOgO extrusion, deep-drawing or injection molding, and are above all suitable ~or the manufacture of shaped articles, eOgO thick and thin ~ilms, sheets and the like, and packaging materialsO
The Examples which ~ollow illustrate the inventionO Unle~s 0OZo 31,895 stated otherwise, parts and percentages are by weight~ Either the intrinsic viscosity, measured in an 0O5 per cent strength solution in toluene at 25C, ;s recorded as a measure of the molecular weight, or the viscometrically determined weight~average molecular t weight is quoted directlyO The impact strength an and notched impact strength ak were determined by the method of DIN 539453, on injection-molded specimensO The transparency was assessed visually, using a 500tU thick filmO In all the Examples, component A of the mixture was a mass-polymerized polystyrene having a molecular weight of ;~
about 200,000 (intrinsic viscosity 85 cm3/g) 9 with an impact strength an of 4~4 kJ/m2 and a notched impact strength a~ of 0.61 kJ/m2O
Component B employed was a star-shaped branched block copoly-mer of the type of the general formula (II), with an average (most probable) structure [polystyrene-poly(butadiene/styrene) --~ polystyrene~ 2-Si-~olystyrene ~ poly(styrene/butadiene~ 2 The overall proportion of styrene in the block copolymer was 73%
20- and the proportion of butadiene was 27%o The terminal free poly-styrene segment contained 76% of the total styrene employed, as copolymerized units, and had an intrinsic viscosity of 37.1 (cm3/g).
The intrinsic viscosity of the star-shaped block copolymer was 90 (cm3/g)O The star-shaped block copolymer was manufactured by successive polymerization of styrene and of a mixture of butadiene and styrene, using n-butyl-lithium as the catalyst, in toluene as the solvent, the initiator being added stepwise and the product then being coupled with silicon tetrachlorideO
The polystyrene (component A) and the star-shaped branched block copolymer (component B) were mixed homogeneously in the ratio of 1O2 in the melt, using an extruderO The mixture had an impact . r .. -19 -` 10~7340 oOZ0 31~895 strength an of 1603 kJ/m2 and a notched impact strength a~ of 2.63 kJ/m20 A film produced from this mixture was transparentO
Component B employed was a star-shaped branched block copoly~ :-mer of the type of the ~eneral formula (I~ 9 with an average ~most probable) structure (polystyrene I - polybutadiene)2 Si~(polybutadiene-polystyrene II)2 The proportion of styrene in the total block copolymer was 75% ~-and the proportion of butadiene was 25%o The polystyrene I segment had an mean molecular weight of 65~000~ whilst that of the poly styrene II segment was lO~OOOo The branched block copolymer had been manufactured by successive polymerization of styrene and butadiene with n-butyl-lithium as the catalyst, the initiator being added in two equal portions in the course of the polymerization of the styrene. Coupling was effected by means Or silicon tetra- :
chlorideO
A mixture produced from the polystyrene (component A) and:. ~
the star-shaped block copolymer (component B) in the ratio of A:B = :~ :
1:2 had an impact strength an of 1603 kJ/m2 and a notched impact strength ak f 20 63 kJ/m20 A film produced from the mixture was -~
transparent.
Component B employed was a star-shaped branched block copolymer of styrene and butadiene of the type of the general formula (I), the olefinic double bonds of the copolymer having been selectively : .
hydrogenatedO The star-shaped block copolymer was manufactured as follows: ;
' 20 7 kg of cyclohexane and 525 g of styrene were titrated with secO-butyl-lithium ;n a 6 l pressure kettle under an inert gas atmosphere, with exclusion of moisture, and were then polymerized with 0033 g of sec. butyl-lithium for 30 minutesO The temperature was initially 54Co 0022 kg of cyclohexane, 009 g of secO-butyl-lithium 1~7340z ~l ~ 8g 5 and 225 g of styrene were added to the active reaction solution at 71C and polymerization was carried out ~or one hour; 10 g of tetrahydro~uran and 250 g of butadiene were then polymerized ~nto the product in the course of one hour at about 74Qco F;nally~
coupling was carried out with 10 ml o~ Epoxol g-5 ~as marketed by Swift Chemical CorpO3 in 150 ml of tolueneO The intrinsic vis-cosity was 91o9 [cm3/g~ The olefinic double bonds o~ the resulting star-shaped block copolymer were then selective1.y hydrogenated9 using a Ni hydro~enation catalyst, until ~he residual content o~
the olefinic double bonds in a block copolymer was less than 1%o Three mixtures, with different ratios o~ the two components, were then produced from the polystyrene (component A) ~nd the selectively hydrogenated star-shaped block copolymer (component B)o The properties of these mixtures are summarized in the Table belowO
All the mixtures have transparent ~ilms~
TABLE
Mixing ratio A:B 1:2 1:1 201 Impact strength an (kJ/m23 140 1 1200 1102 Notched impact strength ak 1053 1036 0091 (kJ/m2 ) .
6(~ ~6~C~Ve2~
. .
.
aromatic compound and a minor proportion of a conjugated dieneO
Examples of monovinyl-aromatic compounds which may be used to synthesize the branched block copolymers are styrene, styrenes 10 with alkyl side-chains, e~gO o~-methylstyrene, and nuclear-substi- ~:
tuted styrenes, eOgO vinyltoluene or ethylvinylbenzene~ The mono-vinyl-aromatic compounds may be employed individually or as mix-tures with one anotherO However, the use of styrene alone is pre-ferredO The conjugated dienes employed are in general of ~ to 8 carbon atomsO Examples of conjugated dienes which may be employed, individually or as mixtures with one another, for the manufacture of the branched block copolymers are butadiene, isoprene and 2,3-dimethyl-butadieneO Butadiene and isoprene give particularly advantageous results, and of the two, butadiene is preferred~
The branched block copolymers of the mixtures according to the invention should contain a total of from 60 to 95 per cent-by weight, especially from 70 to 90 per cent by weight, of the mono- .
vinyl-aromatic compound and from 40 to 5 per cent by weight, pre-ferably from 30 to 10 per cent by weight, of the conjugated diene, in each case based on total monomers employed, as copolymerized unitsO The molecular weight of the branched block copolymers is as a rule from 100,000 to 1,000,000 and preferably from 150,000 to 500,000~ These data relate to the weight-average molecular weight, determined by viscosity measurements on an 005 per cent strength by weight toluene solution at 25C~
The starshaped branched block copolymers to be employed according to the invention have branches consisting of copolymer blocks in which the monovinyl-aromatic compound and the conJugated ~0~7340 oO z o 31~895 diene units are present as blocks, forming individual polymer seg-mentsO These copolymer blocks) themselYes of block structure, which form the branches, are chemically coupled to one another by means of a coupling agentO The star-shaped block copolymers have at least 3, in general from 3 to 10, and preferably 3 or 4, such branches, and these branches should comprise at least two types of copolymer blocks of different average composition~ Furthermore, at least 50 per cent by weight, preferably at least 60 per cent by weight, of all the monovinyl-aromatic compound present as copolymerized units in the star-shaped block copolymer should be contained in the ; terminal homopolymer segment of one or more of the copolymer blocks of the branchesO
The preferred component B of the mixtures of the invention is a star-shaped block copolymer, the most probable average structure of which is represented by one of the ~eneral formulae (I), (II) or (III) below:
(I) (A-B)k-X , (II) (Al_B1 ~ A2)n-X-(A2 ~---- B )m (III) (A3-A4-B2 __~ A5) -X-(A5 ~ B2~A )m ~
In these general formulae (I) - (III), A and A1-A5 are non-elastomeric polymer segments of the mono~inyl-aromatic com-pound, of which the polymer segments A in the polymer (I) should have a polymodal, preferably bimodal, molecular weight distribu-; tion, whilst the individual polymer segments Al-A5 in the poly-mers ~II) and (III) should each have a unimodal molecular weight distribution, B, B and B are elastomeric polymer segments based on the conjugated diene, X is a radical of a polyfunctional cou~ling agent by means of which the copolymer blocks forming the branches are chemically coupled to one another, k is an integer not less ; 30 than 3, in general from 3 to 10 and preferably 3 or 4 and m and n are numbers, m being equal to or greater than n and the sum of m ~7340 o~ z o 31,895 and n bein~ at least 3, in ~eneral an integer from 3 to 10 and preferably 3 or 40 ~.
The symbol ~ in the general formulae (II) and (III) means that the transition between the polymer segments concerned is gradual rather than sharpO
Star-shaped block copolymers of the general formula (A-B)k X (I) have already been dislcosed in German Laid-Open Application DOS 1,959,9220 In these, the non-elastomeric polymer se~ment A is, in particular, a homopolystyrene segment~ The mole-1~ cular weight and polymodality depend pr;mar;ly on the intendedapplication of the end productO As explained in more detail below, the molecular weight is decided by the amount o~ initiator employed per mole of monomer in the manuracturing process; the polymodality depends on the number of times that initiator is added dur;ng the polymerization and is preferably 2 or 3 and espec;ally 2~ The elastomeric polymèr sègment B based on the conjugated dienes is preferably a homopolydiene segment, especially a homopolybutadiene or a homopolyisoprene segment. It may however also contain small amounts, of up to about 30 per cent by weight, preferably of less than 20 per cent by weight, based on polymer segment B, of other copolymerizable monomers, especially of styrene, as copolymerized unitsO
In the star-shaped branched block copolymers which have the most probable average structure of the general formula (II) (A1-B~ A2)n-X-(A2 ~--- B1)m the non-elastomeric polymer segment A1 advantageously contains, as copolymerized units, from 50 to 80 per cent by weight, prefer- ;
ably from 60 to 78 per cent by wei~ht, of the total monovinyl-aromatic compound employed for the manufacture of the branched block copolymer, and is, in particular, a homopolystyren~ segment.
~ Its molecular weight depends primarily on the-application envisaged : for the end product and is preferably from 50,000 to 250,0000 1~7340 O~Z0 31,895 The elastomeric polymer segmtnt B1 is a copolymer block comprising essentially the conjugated diene and a minor proportion of monovinyl-aromatic compound, the distribution of the monomers being sub-stantially randomO The proportion of the monovinyl-aromatic com-pound in the polymer segment B1 is in general less than about 30 per cent by weight and especially less than abcut 20 per cent by weight, based on the amount of monovinyl-aromatic compound of the branched block copolymer not in the form of un;ts o~ the polymer segment A1D The transition between the polymer segments A1 and B1 is sharp, whilst the transition between the polymer segments B1 and A2 is gradual in the sen-e that the proportion of the monovinyl-aromatic compound in the polymer segment B1 increases progressively in the direction of the polymer segment A2 and the proportion Or the conjugated diene accordingly decreases progressivelyO The non-elastomeric polymer segments A2 are, like the polymer segment A1, pref~rably homopolystyrene segments7 The molecular weight o~ the polymer blocks (B1 - A2) is preferably from 10,000 to 100,000.
In the star-shaped branched block copolymers which have most probable average structure of the general formula (III) (A3-A4-B2 ~ A5)n-X-(A5 ~-- B2-A4)m the non-elastomeric polymer segment A3 advantageously contains, as copolymerized units, from 50 to 80 per cent by weight, prefer-; ably from 60 to 75 per cent by weight, of the total monovinyl-aromatic compound employed for the manuracture of the branched block copolymer, and is, in particular, a homopolystyrene segmentO i Its molecular weight is preferably from 509000 to 250,0000 The polymer segments A4 correspond to the polymer segments A3 except that they have a lower molecular weight, usually from 5,000 to 50,0000 They contain, as copolymerized un;ts, from 1 to 30 per cent 3 by weight, preferably from 5 to 25 per cent by weight, of the total monovinyl-aromatic compound, but the sum of the monovinyl-aromatic compound copolymerized in the polymer segments A3 and A4 should ~0~7340 oOz~ 319895 not exceed 90 per cent by weight of the total amount of monovinyl-aromatic compound employed for the manufacture of the branched block copolymersO The elastomeric polymer segment B2 is a copolymer block comprising ess~ntially the conjugated d;ene with a minor proportion of monovinyl-aromatic compound, the distribution of the :~
monomers being substantially randomO The proportion o~ the mono-vinyl-aromatic compound in the polymer segment B2 is in general less than about 30 per cent by weight and especially less than about 20 per cent by weight, based on the amount of monovinyl-aromatic compound not present as units in the polymer segments A3 and A40 The transition between the polymer segments A4 and B2 is sharp, whilst the transition between the polymer segments B2 and A5 is gradual~ The non elastomeric polymer segments A5 are, like the polymer segments A3 and A4, preferably homopolystyrene segments.
The molecular weight of the polymer blocks (A3_A4_B2 _-~ A5) is preferably from 100,000 to 500,000 whilst that of the polymer blocks (A4_B2 > A5) is from 10,000 to lOO~OOOo According to a preferred embodiment of the invention, non-~- elastomeric, star-shaped block copolymers in which the content of - 20 olefinic double bonds has been reduced by selective hydrogenation to less than 5%, preferably less than 2%, are employed as the com-ponent Bo Where selectively hydrogenated derivatives of star shaped branch~d block copolymers of the general formula (I), in which the polymer segment B, prior to hydrogenation, is a polybutadiene seg-ment, are employed, it is necessary to ensure that this polybuta-diene se ment has a 1,2-vinyl content of from 10 to 50 per cent by weight and that after hydrogenation the polymer segment B has a crystallinity of less than 5%, preferably of less than 2% 9 if products having the desired properties are to be obtained~ The 30 crystallinity of the hydrogenated polymer segments B is determined ~.
by differential calorimetry using a Perkin-Elmer DSC calorimeterO
The special composition, and the structure, of the star-shaped branched block copolymers df-pend on, and are determined by, the ` 10~7340 oOzO 31~895 conditions chosen for the polymerization of the monomersO In general, the non elastomeric, star~shaped block copolymers suitable for use :
as component B in the mixtures of the invention are manufactured by successive polymeriza~ion of the monomers ;n solution ;n the presence of a monolithium-hydrocarbon as the initiator, with step-wise addition of monomer and initiator and subsequent coupling of the resulting living linear block copolymers with a polyfunctional reactive compound as the coupling agentO
The initiators used are the conventional mono lithi~m-hydro- :
carbons of the general formula RLi, where R is an aliphatic, cyclo-aliphatic, aromatic or mixed aliphatic-aromatic hydrocarbon radical.
The latter may be of 1 to about 12 carbon atomsO The following may be mentioned as examples of suitable lithium~hydrocarbon initiators:
methyl-lithium, ethyl-lithium, n , secO- and tertO-butyl-lithium, isopropyl-lithium, cyclohexyl-lithium, phenyl lithium and p-tolyl-lithiumO The use of monolithium-alkyl compounds, where alkyl is of 2 to 6 carbon atoms, is preferred, n-butyl-lithium and secO-butyl-lithium being particularly preferredD
The polymerization of the monomers is carried out in solution in an inert organic hydrocarbon solventO Suitable hydrocarbon solvents are aliphatic, cycloaliphatic or aromatic hydrocarbons which are liquid under the reaction conditions and which are pre-ferably of 4 to 12 carbon atomsO Examples Or suitable solvents are isobutane, n pentane, isooctane, cyclopentane, cyclohexane, cyclo-heptane, benzene, toluene, the xylenes, and the likeO Mixtures of these solvents may also be employed, Furthermore, the polymerization can be carried out in the presence of small amounts 3 ;n general from 10 3 to 5 per cent by weight, based on the total colvent, of ethers, e DgO tetrahydrofuran, dimetho~yethane and anisole, thereby 3o influencing, ;n the conventional manner, the rate of polymerization, the configuration of the diene polymer segments and the random transition between the segment B1 and A2, or B2 and A5, in the products of the general formula (II) and (III), respectivelyO
_g_ 1~87340 O~Z~ 319895 The concentration of the monomers in the reaction solution is not critical and can be so chosen that any desired apparatus can be used for the polymerizationO In general, the polymerization is carried out in a solution of from 10 to 30 per cent strength in the inert solvents The polymerization is carried out under the conventional con-ditions for anionic polymerization with lithium-organic compounds, for example in an inert gas atmosphere, with exclusion of air and moistureO The polymerization temperature may be from 0 to 120C
and is preferably kept at from 40 to 80Co The polyfunctional coupling agent used for the coupling reaction carried out after the polymerization should be at least tri~unctional, i.e. it should be capable of reacting with at least three of the active, linear block copolymer chains formed, at their terminal lithium-carbon bonds, to form a chemical bond, so that a single, coupled and accordingly branched block copolymer is formedO The coupling of lithium-terminated living polymers with polyfunctional coupling agents is known in the art and is disclosed, for example, in British Patent 985,6140 Examples of suitable coup-iing agents for the manufacture of the star-shaped block copolymers to be employed according to the invention are polyepoxides, e.g.
epoxidized linseed oil, polyisocyanates, eOgv benzo-1,2,4-triiso- ~-cyanate, polyketones, eO~0 1,3,6-hexanetrione or 1,4,9,10-anthra-cenetetrone, polyanhydrides, eOgO pyromellitic dianhydride, or polyhalidesO Dicarboxylic acid esters, eOgO diethyl adipate or the like, may also be used as coupling agentsO A further preferred group of coupling agents comprises the silicon halides, especially `-silicon tetrachloride, silicon tetrabromide, trichloroethylsilane and 1,2-bis-(methyldichlorosilite)-ethaneO Polyvinyl-aromatics, 0 especially divinylbenzene, may also be used as coupling agents, as disclosed, for example, in UOSo Patent 3,280,0840 In that case, a few divinylbenzene units undergo addition with crosslinking; to form a branching center, by means of which the preformed polymer blocks are bonded to one anot~grO
10~7340 oOzO 31,895 The nature of the polyfunctional coupling agent employed is not critical, provided it does not significantly impair th~ desired properties of the end productO The use of a tri~unctional or tetra-functional coupling agent of the type described3 or o~ divinyl-benzene, is preferredO In general9 the poly~unctional coupling .
agent is added to the reaction solution in amounts equivalent to the total amount of the living polymer blocks, iOe~ equivalent to the number o~ the active lithium-carbon bonds in the previously formed linear copolymer blocksO The reaction Or the living, linear block copolymers with the coupling agent is preferably carried out under the same reaction conditions as the preceding polymerization of the monomersO
Specifically, the non-elastomeric, star-shaped block copoly-mers to be employed in the mixtures o~ the invention are manufactured as follows: in a ~irst processsta~e, a substantial part of the total amount of monovinyl-aromatic compound, in general from 50 to 80 per cent by weight and in particular from 60 to 75 per cent by weight of the total amount of monovinyl-aromatic compound employed for the manufacture of the star-shaped block copolymers, i8 poly-20 merized by means o~ a relatively small amount of the monolithium- :
hydrocarbon initiator until the monovinyl-aromatic compound employed has been completely convertedO The amount of initiator employed in the first process sta~e depends above all on the desired molecular weight of the polymer and is in general from Ool to 5 mmole~ per mole o~ the monovinyl-aromatic compounds employed in this first process stageO Preferably? the polymerization in the first process stage is carried out with from 0~4 to 2~5 mmoles of initiator per mole of the monovinyl-aromatic compounds employed in thls stage~ :
This gives a solution o~ non elastomeric, living polymers of the monovinyl-aromatic compound, with active terminal lithium-carbon bonds, to which further monom~rs can addO In a second process stage~
the remaining monomers are added, all at once or in several successive - stages, to the above reaction solution, after addition of a further ~o~7340 oOzO 31,895 amount of init;ator~ which should be as great or greater than the original amounts of initiator employed ln the first process stage of the polymerizationO Preferably, the amount of fresh ;nitiator added in the second process sta~e is from 1 to 15 times, and especially from 1 to 10 times, the amount of initiator originally employed. It is particularly advantageo~s if this factor ls rrom 1 to 5, especially if trifunctional or tetrafunctional coupling a~ents are employed in the subsequent coupling reaction~ Preferably, the initiator used is the same as in the flrst process stageO It is advanta~eous to introduce the additional fresh initiator into the reaction solution before adding the remaining monomersO
The composition and structure of the resulting block copolymers can be decided, and varied, by varying the manner in which the :
remaining monomers, iOeO both the remaining portion o~ the mono-vinyl-aromatic compound and the conjugated diene, are added to the reaction solution produced in the first process ~tage. For example, the remaining portion of the monovinyl-aromatic compound and the conjugated diene can be added in a single stage, as a mixture;
they can however also be added in several successive stages, for example by separately adding first the remaining portion of the monovinyl-aromatic compound and then the conjugated diene, or first a further partial amount of the monovinyl-aromatic compound and then a mixture of the remaining portion of the monovinyl-aromatic compound and the conjugated diene~ A~ter each fresh addition of monomers in the second process stage, the polymerization is taken to complete conversion of the added monomers before adding further monomer or before ultimately adding the coupling agent If appropriate, further additional amounts of initiator may also be employed repeatedly in the second process stage To produce star-shaped block copolymers of the general formula (I) (A-B)k-X which have a polymodal distxibution in the non-elastomeric polymer segments A formed from the monovinyl-aromatic compounds, the procedure followed is9 for example, first to add ~37340 OOZo 319895 the remaining monovinyl-aromat;c compound, iOeO ~rom 20 to 50 per cent by we;ght, preferably from 25 to 40 per cent by weight9 of the total monovinylaromatic compound employed for the manufacture of the branched block copolymerg in one or more port;ons to the reaction solution manufactured in the first process stage, each addition of a portion of the monovinylaromatic compound being accompanied by the addition Or a further amount of initiator which is as great or greater than the original amount of initiator employed in the rirst process stage of the polymerizationO Though it is possible to add the remaining portion of the monovinyl aromatic compound in as many portions as desired ~o the reaction solution in the course of the second process stage, it ;s pre- -ferred to add the remaining monovinyl-aromatic compound to the polymerization solution in 1 or 2 portions in the course o~ the said process stage, the addition ;n one portion having proved particularly advantageousO The monovinyl-aromatic compounds added in the second process stage undergo addition at the active, lithium-terminated chain ends of the previously formed polymers and also form new chains of living polymers whenever rresh ini-tiator is also addedO Accordingly, after complete polymerization of the remaining monovinyl-aromatic compound, the solution obtained contains polymers of the monovinyl-aromatic compound with difrerent average chain lengths, i~eO the non-elastomeric polymer segements A rormed from the monovinyl aromatic compounds have a polymodal distribution, with the polymodality of the polymer segments A
corresponding to the total number of additions o~ initiator and monomerO Therearter, in a second step, the total amount o~ the conjugated diene i8 added and polymerized to complete conversion.
In the course thereof, the conJugated diene undergoes addition at the active, lithium-terminated chain ends of the previously ~ormed polymodal, non elastomeric polymer segments A to form the elasto-meric polymer segments B, so that the reaction solution contains the copolymer blocks (A-B) which form the branches and which -13~
J~0~73~0 o o z o 31 9 895 possess an active reactive lithium~carbon bond at the ~ree end of the elastomeric diene polymer segment B; these blocks are sub-sequently coupledO
To manufacture star-shaped branched block copolymers of the general formula (II) (Al-Bl ~ A2)n X~(A2 ~ Bl)m the procedure followed in the second process stage o~ the poly-merization is to add, to the fully polymerized reaction solution from the first process stage, first an additional amount of initiator and then a mdxture of the remaining monovinyl aromatic compound and the total amount of the conjugated diene, and to polymerize the mixtureO In the course thereo~, the monomers added in the second process stage undergo addition at the active, living chain ends of the previously formed polymer segments A1, and also form new chains of living polymers, as a result of the fresh initiator addedO Because of the different copolymerization para-meters, the conjugated dienes polymerize substantially more rapidly than the monovinyl-aromatic compounds so that, after addition of the monomer mixture in the second process stage, it is first predominantly the conjugated dienes which undergo polymerization, and only occasionally are units of the monovinyl aromatic compounds copolymerized. Only toward the end of the diene polymerization, iOe. when almost all the conjugated diene has polymerized, does the polymerization of the monovinyl-aromatic compounds commence to a significant degree, so that the predominant proportion ~ as a rule more than 70 per cent by weight, and in most case~ more than 80 per cent by weight - of khe monovinyl aromatic compounds contained in the monomer mixture only polymerizes after the con-jugated dienes have been consumedO Accordinglyg in this case, the second process stage first results in the formation of the elastomeric polymer segment B , based on the conjugated diene, this segment being a copolymer segment mainly comprising the con-~)8 7340 0 Z0 31,895jugated diene, w;th small amounts of the monovinyl aromatlc compound, after which the non-elastomeric polymer segment A~ is ~ormed~ wh;ch is made up of the monovinyl-aromatic compound onlyO S;nce ~he pro~
portion of the monovinyl-aromatic compound progressively increases toward the end of the polymer segment B1 and the proportion of the conjugated diene accordingly progressi~ely decreases~ the transition between the polymer segments B1 and A2 thus formed is not s~arp and instead occurs gradually; this is therefore also frequently described as a blurred tran~ition between the segmentsO After com plete polymerization of the monomer mixture in the second process stage, the reaction solution thus contains a mixture of the linear block copolymers of the type (A1~B1 --j A2~ and (B~ A2)9 with active reactive lithium-carbon bonds in each case at the free end of the polymer segments A29 from which block copolymers the branches are formedO The ratio of the two types of block copolymers in the reaction solution corresponds to the initiator ratio in the first and second process stagesO The mixture of these two types of block copolymers is then coupled, by adding a polyfunctional .
reactive compound, to act as the coupling agent, to the reaction 20 solution.
To manu~acture star-shaped branched block copolymers of the general ~ormula (III) (A3_A4_B2 ~_~ A5~ X~(A5 ~ B2 A4) the procedure ~ollowed in the second process stage of the poly-merization is to add9 to the completely polymeriæed reaction solution from the first process stage~ first a further amount of ;nitiator ~nd then a further 1 30 per cent by weight, preferably 5 - 25 per cent by weight, of the total amount of the monovinyl-aromatic com-pounds used overall for the manufacture of the branched block co-polymersO The sum of the amount of monovinyl-aromatic compound employed in the first and second process stage should however be at most 90 per cent by weight of the total amount of the monovinyl-.. . . .. . .
3~ 0 OOZo 313~95 aromatic compound whîch is employed for the m~nu~actura of the branched block copolymersO The monovinyl aroma~1c compounds added undergo addition at the act;ve, lithium~termînated chain ends of the polymer segments A3 t formed be~orehand in the first process stage, so as now to form the polymer segments A4 a and also ~orm new chains of living polymers of the mono~inyi~aromatic compound as a result of the fresh initiator addedO After complete polymeri-zation of the monovinyl-aromatic compound initially added in the second process stage, the solution obta;ned thus contains living polymers of the monovinyl-aromatic compound with two different average chain lengths, namely, on the one hand9 active liv;ng polymer segments of type (A3-A4~ 9 which have been ~ormed by addition of the monovinyl-aromatic compound, first added in the second pro-cess stage, onto the active livin~ polymer segments A3 formed be-forehand in the first process stage, and, on the other hand9 active living polymer segments of type A4, which have been ~ormed by poly-merization o~ the monovinyl-aromatic compound, ~irst added in the second process stage, with the rresh initiator init;ally introducedO
The ratio in which these two types of non-elastomeric polymer segments based on the monovinyl-aromatic compounds are present in the reaction solution accordingly corresponds to the initiator ratio of the ~irst and second process stagesO Both types o~ polymer :~ segments, (A3 A4) and A4, have active, reactive lithium carbon bonds, capable of undergoing addition of ~urther monomers, at one chain endD A monomer mixture of the remaining monovinyloaromatic compound and the total amount of the conjugated diene is then added to this reaction solution and polymerized until the monomers are virtually completely converted~ As described above~ the polymeri-zation of the monomer mixture comprising the remainin~ monovinyl-aromatic compound and the conJugated d;ene results~ because o~
the different copolymerization parameters of the monomers, rirst in the formation of the elastomeric polymer segment B2 based on the conjugated diene, which segment is a copolymer comprising ~09~7340 O d Z 0 3~,895 mainly the conjugated diene with small amounts of the monovlnyl-aromatic compound, and thereafter in a nonelas~omeric polymer segment A5 which comprises only the monovinyl~aromatic compounds~
Since the monovinyl-aromatic compound is thus copolymerized to a progressively greater degree toward the end of the polymer segment B and the proportion of the conjugated diene accordingly progres-sively decreases, the transition between the polymer segments B2 and A5 which are formed is not sharp but gradualO After complete polymerization of the monomer mixture comprising the remainlng monovinyl-aromatic compound and the conjugated diene, the reaction solution contains a mixture of the linear block copolymers of type (A3-A4-B2 ~ A5) and (A4-B2 ~ A5), having active, reactive lithium;carbon bonds in each case at the free end of the polymer segments A5, which block copolymers form the branches and are subsequently coupled to produce the star-shaped block copolymerO
The branched block copolymers obtained are isolated from the reaction solution in the conventional manner, for example by pre~
cipitating the polymer from the reaction solution and filtering offO
Following the coupling reaction and advantageously prior to isolating the reaction product from the reaction solution, the olefinic double bonds of the branched block copolymers obtained may be subjected to selective hydrogenationO The latter may be carried out in the conventional manner, using molecular hydrogen and catalysts based on metals, or salts of metals, of group 8 of the periodic table, as described, for example, ;n UOSo Patent 3,1~3,986, German Published Application ~AS 1,222,260, German Laid-; Open Application DOS 2,013,263 or UOSo Patent 3,70096330 Accordlng to these publications, the selective hydrogenation of the olefinic double bonds of the branched block copolymer is preferably carried out in a homogeneous phase, using catalysts based on salts,especially carboxylates, enolates or alkoxides, of nickel~ cobalt or iron, which have been reduced with metal alkyls, e~pecially aluminum-alkyls, at hydrogen pressures of from 1 to ~00 bars and ~7340 03Zo 319895 at from 25 to 150Co me selective hydrogenation is continued until the content of olefinic double bonds in the branched block copoly mer has been reduced to less than 5% and pre~erably less than 2%~
This res;dual content is determined by a Wij~ titration or by analysis by IR spectroscopyO In particular, the hydrogenation is continued until the olefinic double bonds have been reduced vir~
tually completelyO Preferably, the hydrogenation is carried out under conditions such that the aromatic double bonds of the branched block copolymer are not attacked at the same timeO
Components A and B of the mixtures of the invention can be homogeneously mixed with one another in the conventional manner using known methods, ~or example by mixing in the melt, using suitable mixing equipment, eOgO kneaders, internal mixers or extrudersO The mixtures may in addition contain the conventional additives for polystyrene, eOgO antistatic agents, stabilizers and the like.
The mixtures of the invention exhibit good transparency and clarity, like polystyrene itself~ The proportion o~ light scattered on passage through a film or sheet serves as a measure of the transparency and clarity. Compared to polystyrene, the mixtures of the invention exhibit substantially improved mechanical proper-ties, and in particular improved impact strength and notched impact strengthO Compared to the non-elastomeric, star-shaped branched block copolymers disclosed in German Laid-Open Application DOS
1,959,922, the mixtures of the invention are cheaper without en-tailing a significant decrease in impact strength and notched impact strength, even if the proportion of polystyrene is relatively higho The mixtures of the invention may be processed easily by conventional methods used for thermoplastics, eOgO extrusion, deep-drawing or injection molding, and are above all suitable ~or the manufacture of shaped articles, eOgO thick and thin ~ilms, sheets and the like, and packaging materialsO
The Examples which ~ollow illustrate the inventionO Unle~s 0OZo 31,895 stated otherwise, parts and percentages are by weight~ Either the intrinsic viscosity, measured in an 0O5 per cent strength solution in toluene at 25C, ;s recorded as a measure of the molecular weight, or the viscometrically determined weight~average molecular t weight is quoted directlyO The impact strength an and notched impact strength ak were determined by the method of DIN 539453, on injection-molded specimensO The transparency was assessed visually, using a 500tU thick filmO In all the Examples, component A of the mixture was a mass-polymerized polystyrene having a molecular weight of ;~
about 200,000 (intrinsic viscosity 85 cm3/g) 9 with an impact strength an of 4~4 kJ/m2 and a notched impact strength a~ of 0.61 kJ/m2O
Component B employed was a star-shaped branched block copoly-mer of the type of the general formula (II), with an average (most probable) structure [polystyrene-poly(butadiene/styrene) --~ polystyrene~ 2-Si-~olystyrene ~ poly(styrene/butadiene~ 2 The overall proportion of styrene in the block copolymer was 73%
20- and the proportion of butadiene was 27%o The terminal free poly-styrene segment contained 76% of the total styrene employed, as copolymerized units, and had an intrinsic viscosity of 37.1 (cm3/g).
The intrinsic viscosity of the star-shaped block copolymer was 90 (cm3/g)O The star-shaped block copolymer was manufactured by successive polymerization of styrene and of a mixture of butadiene and styrene, using n-butyl-lithium as the catalyst, in toluene as the solvent, the initiator being added stepwise and the product then being coupled with silicon tetrachlorideO
The polystyrene (component A) and the star-shaped branched block copolymer (component B) were mixed homogeneously in the ratio of 1O2 in the melt, using an extruderO The mixture had an impact . r .. -19 -` 10~7340 oOZ0 31~895 strength an of 1603 kJ/m2 and a notched impact strength a~ of 2.63 kJ/m20 A film produced from this mixture was transparentO
Component B employed was a star-shaped branched block copoly~ :-mer of the type of the ~eneral formula (I~ 9 with an average ~most probable) structure (polystyrene I - polybutadiene)2 Si~(polybutadiene-polystyrene II)2 The proportion of styrene in the total block copolymer was 75% ~-and the proportion of butadiene was 25%o The polystyrene I segment had an mean molecular weight of 65~000~ whilst that of the poly styrene II segment was lO~OOOo The branched block copolymer had been manufactured by successive polymerization of styrene and butadiene with n-butyl-lithium as the catalyst, the initiator being added in two equal portions in the course of the polymerization of the styrene. Coupling was effected by means Or silicon tetra- :
chlorideO
A mixture produced from the polystyrene (component A) and:. ~
the star-shaped block copolymer (component B) in the ratio of A:B = :~ :
1:2 had an impact strength an of 1603 kJ/m2 and a notched impact strength ak f 20 63 kJ/m20 A film produced from the mixture was -~
transparent.
Component B employed was a star-shaped branched block copolymer of styrene and butadiene of the type of the general formula (I), the olefinic double bonds of the copolymer having been selectively : .
hydrogenatedO The star-shaped block copolymer was manufactured as follows: ;
' 20 7 kg of cyclohexane and 525 g of styrene were titrated with secO-butyl-lithium ;n a 6 l pressure kettle under an inert gas atmosphere, with exclusion of moisture, and were then polymerized with 0033 g of sec. butyl-lithium for 30 minutesO The temperature was initially 54Co 0022 kg of cyclohexane, 009 g of secO-butyl-lithium 1~7340z ~l ~ 8g 5 and 225 g of styrene were added to the active reaction solution at 71C and polymerization was carried out ~or one hour; 10 g of tetrahydro~uran and 250 g of butadiene were then polymerized ~nto the product in the course of one hour at about 74Qco F;nally~
coupling was carried out with 10 ml o~ Epoxol g-5 ~as marketed by Swift Chemical CorpO3 in 150 ml of tolueneO The intrinsic vis-cosity was 91o9 [cm3/g~ The olefinic double bonds o~ the resulting star-shaped block copolymer were then selective1.y hydrogenated9 using a Ni hydro~enation catalyst, until ~he residual content o~
the olefinic double bonds in a block copolymer was less than 1%o Three mixtures, with different ratios o~ the two components, were then produced from the polystyrene (component A) ~nd the selectively hydrogenated star-shaped block copolymer (component B)o The properties of these mixtures are summarized in the Table belowO
All the mixtures have transparent ~ilms~
TABLE
Mixing ratio A:B 1:2 1:1 201 Impact strength an (kJ/m23 140 1 1200 1102 Notched impact strength ak 1053 1036 0091 (kJ/m2 ) .
6(~ ~6~C~Ve2~
. .
.
Claims (8)
1. A mixture which essentially comprises A) from 10 to 70 per cent by weight of polystyrene and B) from 90 to 30 per cent by weight of a thermoplastic, non-elastomeric, star-shaped block copolymer of from 60 to 95% by weight of a monovinyl aromatic compound and from 40 to 5% by weight of a conjugated diene of 4 to 8 carbon atoms, which block copolymer possesses at least two types, of different average composition, of copolymer blocks which form the branches, in which mixture at least 50% by weight of the total monovinyl-aromatic compound present as copolymerized units in the star-shaped block copolymer are present as blocks, in the terminal polymer segment of one or more of the copolymer blocks of the branches.
2. A mixture as claimed in claim 1 which contains, as com-ponent B, a non-elastomeric, star-shaped block copolymer, whereof the olefinic double bonds have been reduced to a residual propor-tion of less than 5% by selective hydrogenation, and whereof the selectively hydrogenated segments have a crystallinity of less than 5%.
3. A mixture as claimed in claim 1, in which the star-shaped block copolymer comprises from 70 to 90% by weight of a monovinyl, aromatic compound and from 30 to 10% by weight of a conjugated diene of 4 to 8 carbon atoms, and at least 60% by weight of the total copolymerized monovinyl aromatic compound in the star-shaped block copolymer is contained in the terminal polymer segment of one or more of the copolymer blocks of the branches.
4. A mixture as claimed in claim 1, in which the star-shaped block copolymer has a viscosity-average molecular weight of from 100,000 to 1,000,000.
5. A mixture as claimed in claim 1, in which a star-shaped block copolymer comprising styrene and butadiene is employed.
6. A mixture as claimed in claim 1, in which a star-shaped block copolymer of the general formula (A-B)k-X is employed, where A is a polymer segment comprising the monovinyl-aromatic compound and having a polymodal molecular weight distribution, B is an elastomeric polymer segment based on a conjugated diene, k is an integer not less than 3 and X is the radical of a polyfunctional coupling agent, by means of which the copolymer blocks (A-B) which form the branches are coupled chemically to one another.
7. A mixture as claimed in claim 1, in which a star-shaped block copolymer of the general formula (A1-B1?A2)n-X-(A2?B1)m is employed, where A1 and A2 are non-elastomeric polymer segments of the monovinyl-aromatic compound, and A1 contains from 50 to 80%
by weight of the total monovinyl-aromatic compound, B1 is an elastomeric polymer segment based on the conjugated diene, the transition between the polymer segments A1 and B1 being sharp whilst the transition between B1 and A2 is gradual, X is a radical of a polyfunctional coupling agent by means of which the copolymer blocks (A1-B1?A2) and (B1?A2), which form the branches, are chemically coupled to one another at the polymer segments A2, and m and n are numbers, m being greater than or equal to n and the sum of m and n being an integer not less than 3.
by weight of the total monovinyl-aromatic compound, B1 is an elastomeric polymer segment based on the conjugated diene, the transition between the polymer segments A1 and B1 being sharp whilst the transition between B1 and A2 is gradual, X is a radical of a polyfunctional coupling agent by means of which the copolymer blocks (A1-B1?A2) and (B1?A2), which form the branches, are chemically coupled to one another at the polymer segments A2, and m and n are numbers, m being greater than or equal to n and the sum of m and n being an integer not less than 3.
8. A mixture as claimed in claim 1, in which a star-shaped block copolymer of the general formula (A3-A4-B2?A5)n-X-(A5?B-A4)m is employed, where A3, A4 and A5 are non-elastomeric polymer seg-ments of the monovinyl-aromatic compound, and A3 contains from 50 to 80% by weight, and A4 from 1 to 30% by weight, of the total monovinyl aromatic compound, but A3 and A4 together do not contain more than 90% by weight of the total monovinyl-aromatic compound, B2 is an elastomeric polymer segment based on the conjugated diene, the transition between the polymer segments A4 and B2 being sharp whilst the transition between B2 and A5 is gradual, X is the radical of a polyfunctional coupling agent by means of which the copolymer blocks (A3-A4-B2 ? A5) and (A4-B1 ? A5), which form the branches, are chemically coupled to one another at the polymer segments A5, and m and n are numbers, m being greater than or equal to n and the sum of m and n being an integer not less than 3.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2610068A DE2610068C2 (en) | 1976-03-11 | 1976-03-11 | Transparent impact-resistant polymer blends |
| DEP2610068.5 | 1976-03-11 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1087340A true CA1087340A (en) | 1980-10-07 |
Family
ID=5972079
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA272,390A Expired CA1087340A (en) | 1976-03-11 | 1977-02-21 | Transparent polymer mixtures having high impact strength |
Country Status (10)
| Country | Link |
|---|---|
| BE (1) | BE852321A (en) |
| CA (1) | CA1087340A (en) |
| DE (1) | DE2610068C2 (en) |
| DK (1) | DK155369C (en) |
| FR (1) | FR2343777A1 (en) |
| GB (1) | GB1570404A (en) |
| IT (1) | IT1075927B (en) |
| NL (1) | NL183359C (en) |
| NO (1) | NO152755C (en) |
| SE (1) | SE416404B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3035637A1 (en) * | 1980-09-20 | 1982-05-06 | Basf Ag, 6700 Ludwigshafen | THERMOPLASTIC MOLDING MATERIAL, USE OF THE MOLDING MATERIAL AND MOLDING PARTS THEREOF |
| DE3248746A1 (en) * | 1982-12-31 | 1984-07-05 | Basf Ag, 6700 Ludwigshafen | THERMOPLASTIC MOLDING |
| DE3816294A1 (en) * | 1988-05-13 | 1989-11-23 | Basf Ag | TRANSPARENT, THERMOPLASTIC SHAPING MATERIAL, METHOD FOR THEIR PRODUCTION AND THEIR USE |
| DE4437501A1 (en) | 1994-10-20 | 1996-04-25 | Basf Ag | Thermoplastic molding compounds |
| DE102008009735A1 (en) | 2008-02-19 | 2009-08-20 | Basf Se | Device for extruding molding compounds |
| EP3019548B1 (en) | 2013-07-02 | 2019-01-30 | INEOS Styrolution Group GmbH | Process for the manufacturing of abs-molding compositions |
| ES2658079T3 (en) | 2013-07-11 | 2018-03-08 | Ineos Styrolution Group Gmbh | Procedure for the production of thermoplastic molding masses, as well as thermoplastic molding masses produced according to it |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1528314A (en) * | 1966-11-07 | 1968-06-07 | Phillips Petroleum Co | Process for preparing polystyrene compositions and novel products thus obtained |
| NL133447C (en) * | 1966-11-07 | |||
| US3639517A (en) * | 1969-09-22 | 1972-02-01 | Phillips Petroleum Co | Resinous branched block copolymers |
| DE2219756C3 (en) * | 1972-01-05 | 1984-04-12 | The General Tire & Rubber Co., 44329 Akron, Ohio | High impact molding compound and process for the production of such molding compounds |
| JPS5232774B2 (en) * | 1974-02-02 | 1977-08-24 | ||
| JPS5216496B2 (en) * | 1974-03-09 | 1977-05-10 |
-
1976
- 1976-03-11 DE DE2610068A patent/DE2610068C2/en not_active Expired
-
1977
- 1977-02-08 IT IT20060/77A patent/IT1075927B/en active
- 1977-02-21 CA CA272,390A patent/CA1087340A/en not_active Expired
- 1977-02-23 NL NLAANVRAGE7701947,A patent/NL183359C/en not_active IP Right Cessation
- 1977-03-03 NO NO770739A patent/NO152755C/en unknown
- 1977-03-08 FR FR7706738A patent/FR2343777A1/en active Granted
- 1977-03-10 SE SE7702728A patent/SE416404B/en not_active IP Right Cessation
- 1977-03-10 BE BE175673A patent/BE852321A/en not_active IP Right Cessation
- 1977-03-10 DK DK104977A patent/DK155369C/en not_active IP Right Cessation
- 1977-03-10 GB GB10099/77A patent/GB1570404A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| FR2343777B1 (en) | 1983-09-16 |
| NL7701947A (en) | 1977-09-13 |
| IT1075927B (en) | 1985-04-22 |
| SE416404B (en) | 1980-12-22 |
| DE2610068A1 (en) | 1977-09-29 |
| SE7702728L (en) | 1977-09-12 |
| NL183359C (en) | 1988-10-03 |
| GB1570404A (en) | 1980-07-02 |
| NO152755B (en) | 1985-08-05 |
| NO770739L (en) | 1977-09-13 |
| DK155369C (en) | 1989-08-07 |
| DE2610068C2 (en) | 1987-02-19 |
| BE852321A (en) | 1977-09-12 |
| FR2343777A1 (en) | 1977-10-07 |
| DK104977A (en) | 1977-09-12 |
| NO152755C (en) | 1985-11-13 |
| DK155369B (en) | 1989-04-03 |
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