WO2001068769A1

WO2001068769A1 - Polymeric composition

Info

Publication number: WO2001068769A1
Application number: PCT/EP2001/003125
Authority: WO
Inventors: Olivier Roumache
Original assignee: Shell Internationale Research Maatschappij BV; Kraton Polymers Research BV
Current assignee: Shell Internationale Research Maatschappij BV; Kraton Polymers Research BV
Priority date: 2000-03-16
Filing date: 2001-03-16
Publication date: 2001-09-20
Anticipated expiration: 2002-09-16
Also published as: AU2001250391A1

Abstract

The present invention relates to a curable polymeric composition comprising (i) a thermoplastic block copolymer containing at least two polymer blocks A separated by at least one polymer block B, wherein polymer block A is primarily a poly(monovinyl aromatic hydrocarbon) block or primarily a poly( C3-C7 alkenoic acid ester) block, and polymer block B is primarily an aliphatic elastomeric polymer block; (ii) a radically polymerisable compound that is at least partially compatible with polymer blocks A, and not compatible with polymer block B, wherein the weight percentage of radically polymerisable compound is in the range from 0.1 to 3 times the weight percentage of polymer blocks A, where both weight percentages are basis the total of block copolymer and radically polymerisable compound; and (iii) a radical initiator that is at least partially compatible with the polymer blocks A and/or the radically polymerisable compound, and not compatible with polymer block B. The present invention further relates to a process for the preparation of a cured polymeric composition; to a cured polymeric composition; to a block copolymer obtainable by curing the curable polymeric composition; to a thermoplastic blend containing the curable polymeric composition or the cured polymeric composition and a polyolefin; and to articles containing any one of the above compositions.

Description

POLYMERIC COMPOSITION

Field of the Invention

The present invention relates to a curable polymeric composition. In particular, it relates to a curable polymeric composition comprising a thermoplastic block copolymer, a radically polymerisable compound and a radical initiator. The invention further relates to a process for curing the curable polymeric composition; to a cured polymeric composition; to a block copolymer; to a thermoplastic blend; and to articles containing the curable polymeric composition, the cured polymeric composition, the block copolymer or the thermoplastic blend.

Background of the invention

Thermoplastic elastomers are well known in the art and many thermoplastic elastomers are available commercially. An important class of thermoplastic elastomers is the class of styrenic block copolymers. These block copolymers are typically characterised by at least two polymer blocks of primarily polymerised monovinyl aromatic hydrocarbon monomers, separated by at least one olefinic polymer block, such as an optionally hydrogenated polymer block of primarily polymerised conjugated diene monomers.

A generally accepted theory to explain the behaviour of styrenic block copolymers is the so-called domain theory. It is thought that the monovinyl hydrocarbon polymer block (s) of a block copolymer molecule form domains with other monovinyl aromatic hydrocarbon blocks of other block copolymer molecules . The domains form physical cross-links between the block copolymer molecules . At a temperature above the glass transition temperature of the olefinic polymer block, but below the glass-transition temperature of the monovinyl aromatic hydrocarbon polymer blocks, the block copolymer is physically cross-linked and elastomeric.

Upon heating the block copolymer above the glass-transition temperature of the monovinyl aromatic hydrocarbon blocks, the domains are softened and the block copolymers become melt-processable . Upon cooling, the domains are formed again.

The glass-transition temperature of e.g. a styrene polymer block is about 95 °C. Upon heating of a styrenic block copolymer, containing styrene polymer blocks as the monovinyl aromatic hydrocarbon blocks, above this glass-transition temperature, the viscosity and the elasticity of the block copolymer remains high due to the non-Newtonian behaviour of the melt, even at high shear rates, compared to homopolymer of the same molecular weight. This behaviour is attributed to the persistence of a two-phase "domain" structure that persists in the melt below the so-called order-disorder transition temperature. In such a domain structure, flow can only take place by the polystyrene polymer blocks of the block copolymer being pulled out of the domains. Selectively hydrogenated block copolymers containing at least two monovinyl aromatic hydrocarbon blocks, e.g. polystyrene blocks, separated by at least one hydrogenated conjugated diene block have very high and very non-Newtonian viscosities because of their extreme segmental incompatibility. Accordingly, processing is difficult and must take place under high shear conditions .

In many applications, a glass-transition temperature of about 95 °C for polystyrene blocks is not sufficient. To increase the high temperature resistance, a so-called "endblock" resin with a much higher glass-transition temperature is often added. Examples of such endblock resins include polyphenylene oxide and poly (α-methylstyrene) . The endblock resin is typically compatible with the monovinyl aromatic hydrocarbon block, but not with the olefinic polymer block.

Although the glass—transition temperature of the aromatic domains can be increased by this method, and, hence, the operating window, the proper blending of the end-block resin into the block copolymer has to take place at a very high temperature, well above the glass transition temperature of the end-block resin. Moreover, the blend viscosity is increased relative to the block copolymer at moderate processing temperature. Accordingly, it would be desirable if a polymeric composition could be found, capable of decreasing the viscosity of styrenic block copolymers during processing and, preferably, capable of imparting good high temperature properties, whilst preferably retaining other useful properties of the polymeric composition.

Surprisingly, such a polymeric composition has now been found. Summary of the invention

The present invention relates to a curable polymeric composition comprising

(i) a thermoplastic block copolymer containing at least two polymer blocks A separated by at least one polymer block B, wherein polymer block A is primarily a poly (monovinyl aromatic hydrocarbon) block or primarily a poly(C3~C7 alkenoic acid ester) block, and polymer block B is primarily an aliphatic elastomeric polymer block; (ii) a radically polymerisable compound that is at least partially compatible with polymer blocks A, and not compatible with polymer block B, wherein the weight percentage of radically polymerisable compound is in the range from 0.1 to 3 times the weight percentage of polymer blocks A, where both weight percentages are basis the total of block copolymer and radically polymerisable compound; and (in) a radical initiator that is at least partially compatible with the polymer blocks A and/or the radically polymerisable compound, and not compatible with polymer block B.

The radically polymerisable compound is at least partially compatible, preferably compatible, with polymer blocks A and acts as a solvent, weakening the domains formed by the A blocks. Upon curing, the radically polymerisable compound forms a resin that is typically compatible with the same polymer blocks A, but not with polymer blocks B and preferably imparts good high temperature properties on the cured polymeric composition. In one preferred embodiment, the cured polymeric composition is typically still thermoplastic. The present invention further relates to a process for the preparation of a cured polymeric composition, which comprises radically polymerising the radically polymerisable compound in the curable polymeric composition as described herein at a temperature below the order-disorder transition temperature of the polymeric composition.

The present invention further relates to a cured polymeric composition, obtainable by curing the curable polymeric composition as described herein; and to a block copolymer containing at least two polymer blocks A, and at least one polymer block B, wherein polymer block B is primarily an aliphatic elastomeπc polymer block and polymer block A is primarily a monovinyl aromatic hydrocarbon polymer block further containing polymerised (radically polymerisable compound), obtainable by curing the curable polymeric composition as described herein. In addition, the present invention relates to articles containing the curable polymeric composition, the cured polymeric composition or the block copolymer.

For the purposes of this specification, the order-disorder transition temperature (ODT) is the temperature at which the A and B blocks of the block copolymer are sufficiently compatible to form a single phase. The order-disorder transition temperature is well known m the art and described extensively in e.g. Thermoplastic Elastomers - A Comprehensive Review, edited by N.R. Legge, G. Holden and H.E. Schroeder (1987), Carl Hanser Verlag Munich, Chapter 12/3 by T. Hashimoto, incorporated herein by reference.

The order-disorder transition temperature is dependent on any other components in the polymeric composition that may strengthen or weaken the domain structure of the block copolymer m the polymeric composition. The order-disorder transition temperature is determined by small-angle X-ray scattering (SAXS) profiles, as described in the above referenced publication. The order-disorder transition temperature can be approximated by alternative methods such as proton NMR or DMTA as described by CD. Han and J. Kim m ^ΛMacromolecules (1989), 22, p.383-394' and m ^Λ Journal of polymer science Part B: Polymer Physics 25, p.1741 (1987) and 26, p.677 (1988)'). A particularly suitable method to determine the order-disorder temperature via Dynamic Mechanical Thermal Analysis (DMTA) is described by J. LaMonte Adams, William W. Graessley and Richard A. Register in 'Macromolecules (1994), 27, 6026-6032'. In the latter reference, the microphase separation transition temperature (Tmst), in other words the order-disorder transition temperature (Todt), is measured by an abrupt drop in the isochronal curve plot of G' (at low frequencies) versus temperature. For the purposes of this specification, the compatibility between two ingredients can be assessed via the transparency and macroscopic homogeneity of a mixture of the two considered ingredients at their weight ratio used in the formulation and at room temperature. Such mixture is said to be compatible if transparent and without any bleeding out or macroscopic separation of one ingredient from the mixture. At the opposite, two ingredients are said to be incompatible if the said mixture exhibits a non-transparent (i.e. milky) appearance and/or if at least one ingredient has a macroscopically evident tendency to bleed out of the mixture. This compatibility concept has been described in US patent specification No. 3,917,607, incorporated herein by reference.

If an ingredient I is at least partially compatible with a polymer block A and not compatible with a polymer block B, then a mixture of I with a pure B polymer must exhibit more incompatibility than the equivalent mixture where the pure B polymer is replaced by a block copolymer of A and B blocks. Detailed description of the invention

Block copolymers are well known in the art and available commercially. A variety of polymerisation processes can be employed, but anionic polymerisation in the presence of an organic alkali-metal-containing initiator is preferred.

Polymer block A is primarily a poly (monovinyl aromatic hydrocarbon) block or primarily a poly(C3~C7 alkenoic acid ester) block, such as a poly (acrylate) block. Both polymer blocks are anionically polymerisable.

For the purposes of this invention "primarily" means in relation to polymer block A, that the polymer block A is composed of at least 75% by weight, preferably at least 90% by weight of monovinyl aromatic hydrocarbon or C3-C7 alkenoic acid ester as the case may be. The remainder of the block is typically a polymerised olefinic monomer or, respectively, a C3-C7 alkenoic acid ester or a monovinyl aromatic hydrocarbon. Obviously, also mixtures of several C3-C7 alkenoic acid esters or several monovinyl aromatic hydrocarbons may be employed. More preferably, polymer block A is substantially composed of the same polymerised monomer, that is, more preferably, polymer block A is composed of at least 95% by weight of a monovinyl aromatic hydrocarbon or a C3-C7 alkenoic acid ester.

Preferably, polymer block A is a poly (monovinyl aromatic hydrocarbon) block.

Polymer block B is primarily an aliphatic elastomeric polymer block.

For the purposes of this invention "primarily" means in relation to polymer block B, that the polymer block B is composed of at least 75% by weight, preferably at least 90% by weight of an aliphatic elastomer. The remainder of the block is typically polymerised C3-C7 alkenoic acid ester and/or monovinyl aromatic hydrocarbon. More preferably, polymer block B is substantially composed of the same polymerised monomer, that is, more preferably, polymer block B is composed of at least 95% by weight of an aliphatic elastomer. Preferably, polymer block B is a hydrogenated poly (conjugated diene) block.

The block copolymer typically has the structure A-B-A' , A-B-A'-B', (A-B)nX or (A-B) pX (B' ( -A' ) r ) q, wherein X is the residue of a coupling agent, A' and B' are polymer blocks of the same or different molecular weight as polymer blocks A and B respectively and polymer blocks A' and B' are selected from the same group of chemical compounds as polymer blocks A and B respectively; n > 2; p > 1; r is 0 or 1; q > 1; and (r*q + p) > 2. Preferably, n < 100 and (p + q) < 100; more preferably n < 20 and (p + q) < 20; in particular n < 6 and (p + q) ≤ 6.

The block copolymer may be a blend of block copolymers and/or may contain up to 80% by weight of a diblock copolymer containing one polymer block A and one polymer block B, basis the total block copolymer content. The preferred amount of diblock copolymer very much depends on the targeted end-use. Thus, if for instance it is desired to provide a tacky adhesive composition, the desired amount of diblock copolymer may be rather high.

Preferably, the diblock copolymer content, if any, is not more than 40% by weight, more preferably not more than 30% by weight. According to one embodiment, the block copolymer does not contain diblock copolymer. As outlined before, the block copolymer may be prepared by any method known in the art and is typically be prepared by anionic polymerisation. For example, the block copolymer may be prepared by anionic polymerisation using the well-known full sequential polymerisation method, optionally in combination with re-initiation, or the coupling method. Anionic polymerisation of block copolymers is well known in the art and has e.g. been described in US patent specification Nos. 3,595,942; 3,322,856; 3,231,635; 4,077,893; 4,219,627; and 4,391,949, and International and European patent application publication Nos. EP 0413294, EP 0387671, EP 0636654, and WO 94/22931, incorporated herein by reference .

To prepare an aliphatic polymer block B via anionic polymerisation, typically first a conjugated diene is polymerised and the olefinic unsaturation selectively hydrogenated using hydrogenation catalysts. Selective hydrogenation of conjugated dienes is also well known in the art and has e.g. been described in US patent specification Nos. 3,595,942, 3,700,633, 5,925,717; 5,814,709; 5,886,107; and 5,952,430, incorporated herein by reference.

In the selectively hydrogenated block copolymer to be used in the polymeric composition of the present invention, typically at least 80%, preferably at least 90%, more preferably at least 95%, in particular at least 99% of the double bonds in the conjugated diene block (s) is hydrogenated. The hydrogenation degree can be analysed using the nuclear magnetic resonance (NMR) method. Preferably not more than 25% by weight, more preferably not more than 10%, in particular not more than 5% of any monovinyl aromatic hydrocarbon is hydrogenated.

Preferably, the monovinyl aromatic hydrocarbon is chosen from the group of styrene, C^-C^ alkylstyrene and C_]_-C_] dialkylstyrene, in particular styrene, α-methylstyrene, o-methylstyrene or p-methylstyrene, 1, 3-dimethylstyrene, p-tert . -butylstyrene or mixtures thereof, more preferably styrene or α-methylstyrene, most preferably styrene.

Preferably, the C3-C7 alkenoic acid ester is a compound containing C3-C7 alkenoic acid ester groups of formula B,

wherein R]_ is hydrogen or a C1-C4 alkyl group; R₂ is a C_]_-C3 alkane group; R3 is a C^-Cø arene, alkane or cycloalkane group; R4 is hydrogen or a methyl group; a is 0 or 1, more preferably 0. The C3-C7 alkenoic acid ester is even more preferably chosen from the group of acrylates, methacrylates, methylacrylates and methylmethacrylates (that is, in formula B, a is 0 and Ri and R4 are hydrogen or methyl), most preferably butylacrylate (i.e. in Formula B, a is 0; R_j_ and R4 are hydrogen and R3 is a butyl group) .

Preferably, the conjugated diene is chosen from conjugated dienes containing from 4 to 24 carbon atoms, more preferably from 4 to 8 carbon atoms, in particular butadiene or isoprene. If the conjugated diene is butadiene it is preferred to polymerise a substantial part of the butadiene via 1,2-addition rather than 1, 4-addition. Preferably, the amount of butadiene that is polymerised via 1,2-addition is at least 25% of the total amount of polymerised butadiene. In other words, the so-called 1,2-vinyl content prior to hydrogenation is preferably at least 25%, more preferably in the range from 30 to 90%. Techniques to enhance the vinyl content of the butadiene portion are well known and may involve the use of polar compounds such as ethers, amines and other Lewis bases and more in particular those selected from the group consisting of dialkylethers of glycols. Most preferred modifiers are selected from dialkyl ether of ethylene glycol containing the same or different terminal alkoxy groups and optionally bearing an alkyl substituent on the ethylene radical, such as monoglyme, diglyme, diethoxyethane, 1, 2-diethoxy-propane, l-ethoxy-2, 2-tert- butoxyethane, of which 1, 2-diethoxypropane is most preferred.

Preferably, the polymer blocks A comprise from 5 to 90% by weight of the block copolymer, more preferably from 10 to 60% by weight, even more preferably from 10 to 45% by weight, in particular from 13 to 35% by weight .

The polymer blocks A typically have a weight average molecular weight in the range from 3,000 to 100,000; preferably from 4,000 to 60,000; more preferably from 5,500 to 15,000 g/mol . The polymer blocks B typically have a weight average molecular weight m the range from 10,000 to 300,000; preferably from 30,000 to 180,000; more preferably from 35,000 to 100,000 g/mol . The total block copolymer typically has a weight average molecular weight in the range from 16,000 to 1,000,000; preferably from 25,000 to 900,000. If the block copolymer is linear, more preferably the weight average molecular weight is m the range from 30,000 to 200,000, m particular m the range from

35,000 to 150,000. If the block copolymer is radial, more preferably the weight average molecular weight of each arm is in the range 10,000 to 100,000 and the total weight average molecular weight is m the range 35,000 to 500,000.

Weight average molecular weight as referred to herein is real weight average molecular weight in gr/mole. It is re-calculated, taking into account the actual chemical composition of the polymer, its structure and the precise measurement of the real A blocks molecular weight determined by gel permeation chromatography in accordance with ASTM D 3536 using pure A homopolymer standards.

The radically polymerisable compound must be at least partially compatible with polymer blocks A and is not compatible with polymer blocks B. Moreover, preferably, the radically polymerisable compound after polymerisation is still compatible with polymer blocks A.

For the purposes of this specification, "compatible" is defined as outlined herein above. The radically polymerisable compound is preferably present in an amount such that the weight percentage of radically polymerisable compound is less than 2.5 times the weight percentage of polymer blocks A, wherein both weight percentages are basis the total of block copolymer and radically polymerisable compound. More preferably, the weight percentage of radically polymerisable compound is in the range from 0.5 to 2 times the weight percentage of polymer blocks A, on the same basis.

The radically polymerisable compound can suitably be any compound that satisfies the above criteria. It is thought that the solubility parameter of the radically polymerisable compound is typically close to the solubility parameter of polymer block A and not close to the solubility parameter of polymer block B. The solubility parameter is well known to those skilled in the art and has been described in 'Polymer Handbook' third edition (1989) edited by J. BRANDRUP and E.H. IMMERGUT, John Wiley & Sons (ISBN 0-471-81244-7), incorporated herein by reference. The book describes a group contribution method, which can be used to estimate the solubility parameter of a chemical compounds based on the knowledge of their chemical structure and their density. Solubility parameters calculated using the group contribution method and using the measured densities listed in the same book are ( (cal/cm^) 1/2 } : amorphous polystyrene: 9.02; amorphous polyethylene: 8.26; amorphous polypropylene: 7.77; amorphous polybutene-1 : 7.89.

Typically, the solubility parameter of the radically polymerisable compound should be in the range from

-0.5 to +1.0 { (cal/cm.3) 1/2 } of the solubility parameter of the polymer block A, preferably, in the range from -0.15 to +0.5.

If e.g. the polymer blocks A are poly (styrene) blocks, the radically polymerisable compound preferably has a solubility parameter in the range from 8.52 to 10.02, preferably, in the range from 8.87 to 9.52.

The radically polymerisable compound is preferably chosen from the group of styrene, C;[-C4-alkylstyrene, Cι_C4-dialkylstyrene, compounds containing C3-C7 alkenoic acid ester groups, divinyl benzene, and divinyl C1-C4 alkyl benzene.

More preferably, the radically polymerisable compound is a compound containing C3-C7 alkenoic acid ester groups of formula A,

wherein Rη_ is hydrogen or a C1-C alkyl group; R is a C -C3 alkane group; R3 is a C_-Cg arene, alkane or cycloalkane group; R4 is hydrogen or a methyl group; a is 0 or 1; and b is an integer in the range from 1 to 6.

More preferably, the compound containing C3-C7 alkenoic acid ester groups is selected from those compounds represented by formula A in which a is 0 and b is an integer in the range from 1 to 4.

According to one embodiment, the curable polymeric composition is still thermoplastic after curing. Thus, according to a preferred embodiment of the invention, a thermoplastic polymeric composition can be prepared that is still processable at high temperatures and returns to the original form e.g. at room temperature. Accordingly, a thermoplastic composition can now been provided that is easily processable prior to curing, and after curing is still processable and has certain improved properties such as a higher temperature resistance. The processability of the polymeric composition after curing is considered important e.g. from an environmental point of view as it allows recycling of the polymeric composition .

For a curable polymeric composition that is still thermoplastic after curing, it is preferred that the radically polymerisable compound is chosen from monovinyl containing compounds, more preferably chosen from the group of styrene, C;[-C4-alkylstyrene, C]_-C4~dialkyl- styrene, and saturated compounds containing one C3-C7 alkenoic acid ester group. Alternatively, it is also possible to obtain a curable polymeric composition that is still thermoplastic after curing when the radically polymerisable compound is chosen from divinyl or polyvinyl containing compounds . However, in that case it is important that the weight percentage of polymer block A, radically polymerisable compound, radical initiator, and any polymer block A compatible oil or resin is not more than 30%, and preferably not more than 25% by weight basis the total block copolymer and auxiliaries that are compatible with either the A or the B polymer blocks; and moreover it is preferred that the total weight average molecular weight of the block copolymer is not more than 125,000. According to another embodiment, the present invention relates to a curable polymeric composition that is thermoset after curing, wherein the radically polymerisable compound is chosen from divinyl or polyvinyl containing compounds; wherein the total weight average molecular weight of the block copolymer is more than 160,000 if the weight percentage of polymer block A, radically polymerisable compound, radical initiator, and any polymer block A compatible oil or resin is less than 30% by weight basis the total block copolymer and auxiliaries that are compatible with either the A or the B polymer blocks. Cured thermoset polymeric compositions are known in the art. Known cured thermoset polymeric compositions, however, are often cross-linked through the polymer block B. This has an adverse effect on elastomeric properties of the cured polymeric composition. It would be desirable if a system could be found that cross-links the polymer blocks A rather than B.

US patent specification No. 4,556,464 describes an endblock cross-linked block copolymer composition. The block copolymer has the structure A-B-A, wherein B stands for a not-hydrogenated conjugated diene polymer block and A stands for a not-hydrogenated copolymer block of a conjugated diene and an aromatic hydrocarbon. An acrylate that was compatible with the A blocks was used to cross-link the system. Despite the higher concentration of cross-links in the A blocks, a significant amount of cross-links were still made in the B block.

US patent specification No. 4,151,057 describes a cured adhesive composition which comprises a di-to-tetra-functional acrylate or methacrylate as cross-linking agent and a selectively hydrogenated

S-EB-S block copolymer, where S stands for a polystyrene block and EB stands for an ethylene/butylene block (which is the structure that forms when hydrogenatmg a butadiene block) . The polymeric composition is cured by electron beam radiation, which results m cross-linking through primarily the B blocks .

US patent specification No. 5,066,728 describes block copolymers of structure A-B-A, where the A blocks are more reactive than the B blocks when cured with electron beam radiation. The A blocks consist of poly (2-phenyl- butadiene) and the B blocks consist of polybutadiene or polyisoprene. The patent specification describes that the amount of cross-linking in the A blocks is significantly higher than for alternative polymeric systems known at the time. However, if good heat-agemg resistance, weatherability and resistance to oxidation are desired, then selectively hydrogenated block copolymers are preferred .

The curable polymeric composition of the present invention comprises a block copolymer containing little, if any, olefinic unsaturation; and upon curing the block copolymer is primarily cross-linked through the polymer blocks A and not through the polymer blocks B.

The curable polymeric composition of the present invention must comprise a radical initiator. The radical initiator should be at least partially compatible with the polymer blocks A and/or the radically polymerisable compound, and, preferably, is not compatible with the B blocks. Examples of suitable radical initiators include photo-mitiators and thermal radical initiators, that is, radical initiators which decompose at a certain temperature to form radicals.

Examples of such thermal radical initiators are peroxide compounds and azo compounds. Many of such compounds are well known in the art and available commercially. Specific compounds differ m the temperature at which they decompose to form radicals. It s important to know the half-life of the thermal radical initiator for determining ts useful temperature range.

Thus, e.g. the temperature at which the half-life t_]_/ of benzoyl peroxide is one hour is 91 °C and the temperature at which the half-life is ten hours is 71 °C. For t-butyl perbenzoate the temperature is 125 °C or 105 °C for t_]_/ being 1 hour or 10 hours respectively. For l,l'-azobιs- (cyclohexanecarbonitπle) the temperature is 105 °C or 88 °C for t]_/ being 1 hour or 10 hours respectively.

It belongs to the skilled of the skilled person to select an appropriate thermal radical initiator, with the appropriate half-life at the right temperature. As will be discussed in more detail herein after, care should be taken that the thermal radical initiator is used at a temperature that is below the order-disorder transition temperature of the block copolymer in the polymeric composition. Azo compounds and peroxy compounds have been discussed in detail in the Encyclopedia of Polymer Science and Engineering, John Wiley & Sons (1988), volume 2, pages 143-157 and volume 11, pages 1-21 respectively, incorporated herein by reference. It is expected that a particular useful group of thermal radical initiators are those initiators that are commonly used in the radical polymerisation of styrene to manufacture of polystyrene. Examples of commercially available compounds are (see also volume 16, page 26 of the above encyclopaedia): 2, 2' -azobis (isobutyronitrile) ; 2,2'-azobis(2, 4 -dimethyl aleronitrile) ; l,l'-azobis- (cyclohexanecarbonitrile) ; benzoyl peroxide; t-butyl 2-methylperbenzoate; dicumyl peroxide; t-butyl cumyl peroxide; di-t-butylperoxide; 1 , 1-di ( t-butyl- peroxy) -3, 3, 5-trimethylcyclohexane; dilauroyl peroxide; di (2-ethylhexyl ) peroxydicarbonate; t-amyl peroctoate; t-butyl peracetate; t-butyl perbenzoate; 2 , 5-bis (benzoyl- peroxy) -2, 5-dimethylhexane; di-t-butyldiperoxyazelate; and 1, 1-di ( t-butylperoxy) cyclohexane .

According to one preferred embodiment, the radical initiator is a photo-initiator. Photo-initiators are known in the art and examples of suitable photo-initiators have been disclosed in European patent specification No. 0 696 761 and US patent Nos. 4,894,315; 4,460,675 and 4,234,676. Typically, the photo-initiator is selected from optionally substituted polynuclear quinones, aromatic ketones, benzoin and benzoin ethers and 2 , 4 , 5-triarylimidazolyl dimers . The photo-initiator is preferably selected from the group consisting of: (1) a benzophenone of the general formula (I) - I f

wherein R¹ to R⁶ independently represent hydrogen or an alkyl group having from 1 to 4 carbon atoms, preferably methyl, and wherein R^ and/or R^ have the same meaning as R^ to R^ or represent in addition alkoxy or 1 to 4 carbon atoms and wherein n has a value of 0, 1, or 2, optionally in combination with at least one tertiary a ine,

(2) a sulphur-containing carbonyl compound, wherein the carbonyl group is directly bound to at least one aromatic ring and is preferably of the general formula II wherein R", R!0, and RU each may represent hydrogen, alkyl of 1 to 4 carbon atoms, or an alkylthio having 1 to 4 carbon atoms, and

(3) mixtures of (1) and (2) .

Examples of suitable compounds of category (1) are benzophenone, 2 , 4 , 6-trimethylbenzophenone, 4-methylbenzo- phenone, and eutectic mixtures of 2 , 4 , 6-trimethylbenzophenone and 4-methylbenzophenone (ESACURE TZT), or 2, 2-dimethoxy-l, 2-diphenylethan-l-one (IRGACURE 651) (ESACURE and IRGACURE are trademarks) . These compounds may be employed in combination with tertiary amines, such as e.g. UVECRYL 7100 (UVECRYL is a trademark) . Category (2) embraces compounds such as, e.g., 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino- propanone-1, commercially available as IRGACURE 907. An example of suitable mixtures (category (3)) is a mixture of 15 percent by weight of a mixture of 2-isopropyl- thioxanthone and 4-isopropylthioxanthone, and 85 percent by weight of a mixture of 2, 4 , 6-trimethylbenzophenone and 4-methylbenzophenone . This mixture is commercially available under the trade name ESACURE X15. Photo-initiators of any one of the above categories (1), (2), and (3) may also be used in combination with other photo- initiators, such as e.g. UVECRYL P115 (a diamine) . Particularly useful is a combination of benzophenone or IRGACURE 651 and said UVECRYL P115.

In a more preferred embodiment of the present invention the photo-initiator is selected from the group consisting of (i) benzophenone, or 2 , 2-dimethoxy-l , 2-di- phenylethan-1-one (IRGACURE 651) , (ii) a mixture of benzophenone or IRGACURE 651, and a tertiary amine, and (iii) 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino- propanone-1. Of these 2-methyl-l- [ 4- (methylthio) phenyl] - 2-morpholinopropanone-l or 2, 2-dimethoxy-l , 2-diphenyl- ethan-1-one are most preferred.

Typically, the photo-initiator is present in an amount from 0.005 to 15 parts by weight per 100 parts by weight of radically polymerisable compound, preferably from 0.1 to 5 parts by weight.

The curable polymeric composition as described herein may further comprise an aliphatic or cycloaliphatic diluent, or a mixture of diluents, compatible with polymer blocks B, but not with polymer blocks A preferably not with the radically polymerisable compound or the radical initiator.

Examples of suitable aliphatic and cycloaliphatic diluents are: paraffinic process oils (e.g. CATENEX SM925); naphthenic oils; fully or highly hydrogenated process oils (e.g. ONDINA N68 or PRIMOL 352); waxes; liquid hydrogenated aromatic resins (e.g. REGALITE R1010) ; liquid polyalphaolefins (e.g. DURASYN 166) ; and liquid polymers such as hydrogenated polyisoprene, hydrogenated polybutadiene or polybutene-1 (CATENEX, ONDINA, PRIMOL, REGALITE and DURASYN are trademarks) .

The diluents, if present, may typically be present in an amount up to 2000 parts by weight per "100 parts by weight of polymer blocks B" , depending on the end-use application. In general, the amount of diluent will be in the range from 20 to 400 parts by weight.

In addition, or alternatively, the curable polymeric composition may further comprise a tackifying resin compatible with polymer blocks B, but not with polymer blocks A. Tackifying resins are well known to those skilled in the art. A wide variety of different tackifying resins are available commercially. The tackifying resin to be used in the present invention is preferably a partially or fully hydrogenated aliphatic hydrocarbon resin or rosin ester or a fully hydrogenated aromatic hydrocarbon resin.

Specific examples of suitable tackifying resins are: hydrogenated styrene-based resins such as REGALREZ resins designated as 1018, 1033, 1065, 1078, 1094 and 1126; REGALREZ 6108, a 60% hydrogenated aromatic resin; hydrogenated tackifying resins based on C5 and/or C9 hydrocarbon feedstocks such as ARKON P-70, P-90, P-100, P-125, P-115, M-90, M-100, M-110 and M-120 resins and REGALITE R-100, MGB-63, MGB-67, and MGB-70 resins; hydrogenated Polycyclopentadienes such as ESCOREZ 5320, 5300 and 5380 resins; hydrogenated polyterpene and other naturally occurring resins such as CLEARON P-105, P-115, P-125, M-105 and M-115 resins and EASOTACK H-100, H-115 and H-130 resins (REGALREZ, ARKON, ESCOREZ, CLEARON and

EASOTACK are all trademarks) .

The tackifying resin typically has a softening point as determined by the Ring and Ball method (ASTM E 28) of at least 70 °C, preferably in the range of from 75 to

125 °C, more preferably 80 to 105 °C.

According to a particularly preferred embodiment, the tackifying resin is a fully hydrogenated hydrocarbon resin . The tackifying resins, if present, may typically be present m an amount of up to 500 parts by weight per

"100 parts by weight of polymer blocks B" , depending on the desired end-use application. In general, the amount of tackifying resin, if present, will be in the range from 10 to 200 parts by weight.

The curable polymeric composition, optionally comprising tackifying resins and/or diluents, may be blended with a polyolefm. Examples of suitable polyolefms are polyethylene, polypropylene, polybutene-1, copolymers of these polyolefms, EPDM and other polyolefm elastomers, including those lower density polyolefms made with so-called metallocene catalysts .

The polyolefms, if present, may typically be present in an amount of up to 2500 parts by weight per "100 parts by weight of polymer blocks B" , depending on the desired end-use application.

If polyolefms are present in an amount such that they form the matrix of the blend with the curable polymeric composition, a thermoplastic blend may be produced upon curing of the curable polymeric composition, even if the said composition as such would be thermoset after curing.

It is contemplated that a thermoplastic vulcamsate can be formed by dynamic vulcanisation (curing) of the curable polymeric composition, whilst blending with a polyolefin in an extruder. The extruder should operate at a temperature below the order-disorder temperature of the curable polymeric composition, but this is easily achievable, especially if relatively high molecular weight (Mw > 160,000 g/mol) block copolymers are used.

Therefore, the present invention further relates to a thermoplastic blend comprising from 125 to 2500 parts by weight, preferably from 150 to 2000 parts by weight, of a polyolefin per 100 parts by weight of a curable polymeric composition or a cured polymeric composition as described herein. Preferably, the polymeric composition as such is thermoset after curing.

Stabilisers such as antioxidants/UV stabilisers/ radical scavengers may in addition be present in the curable polymeric composition.

Especially hindered phenols, organo-metallic compounds, aromatic amines, aromatic phosphites and sulphur compounds are useful for this purpose. Preferred stabilisers include phenolic antioxidants, thio compounds and tris (alkyl-phenyl) phosphites.

Examples of commercially available antioxidants/ radical scavengers are pentaerythrityl-tetrakis (3, 5-di- tert-butyl-4-hydroxy-hydrocinnamate) (IRGANOX 1010); octadecyl ester of 3,5-bis ( 1, 1-di-methylethyl) -4-hydroxy benzene propanoic acid (IRGANOX 1076); 2,4-bis (n-octyl- thio) -6- (4-hydroxy-3, 5-di-tert-butylanilino) -1,3, 5-tria- zine (IRGANOX 565); 2-tert-butyl-6- (3-tert-butyl-2 ' -hy- droxy-5-methylbenzyl ) -4-methylphenyl acrylate (SUMILIZER GM) ; tris (nonylphenyl) phosphite; tris (mixed mono- and di-phenyl) -phosphite; bis (2 , 4-di-tert-butylphenyl) - pentaerythritol diphosphite (ULTRANOX 626) ; distearyl pentaerythritol diphosphite (WESTON 618); styrenated diphenylamine (NAUGARD 445); N-l, 3-dimethylbutyl-N ' - phenyl-paraphenylenediamine (SUMILIZER 116 PPD) ; tris (2, 4-dι-tert-butylphenyl) phosphite (IRGAFOS 168); 4,4- butylidene-bis- ( 3-methyl-6-tert-butylphenol ) (SUMILIZER BBMS) (IRGANOX, SUMILIZER, ULTRANOX, WESTON, NAUGARD and IRGAFOS are trademarks) . The stabiliser (s ) is (are) typically present m the curable polymeric composition in a total amount from 0.01 to 5% by weight, basis the total curable polymeric composition, preferably 0.2 to 3% by weight.

Other well-known components that may be present include polymerisation inhibitors, anti-ozonants , colorants, fillers or reinforcing agents. It belongs to the skill of the skilled person to select the appropriate additional components in the appropriate amounts.

Curing processes that induce radical polymerisation with a radical initiator are well known in the art. As set out herein before, it is important that the curing is carried out at a temperature below the order-disorder transition temperature of the polymeric composition. If the curing is carried out above this temperature, little cross-linking in the polymer blocks A will take place (for thermoset compositions) and e.g. the high temperature properties or other desired properties will not improve at all or not to the same extent.

If a photo- itiator is present, the curable polymeric composition is cured by actinic radiation. This can be daylight or an artificial actinic radiation source. Usually, the photo-mitiator used is most sensitive in the ultraviolet range. Therefore, preferably, the artificial radiation source should furnish an effective amount of this radiation, more preferably having an output spectrum the range from 200 to 500 nm, even more preferably in the range from 230 to 450 nm. Particularly suitable UV sources are FUSION bulb lamps having output maxima at 260-270 nm, 320 nm and 360 nm ("H" bulb), at 350-390 nm ("D" bulb) or at 400-430 nm ("V" bulb) (FUSION is a trademark) . Combinations of these FUSION bulb lamps may also be used. H and D bulb lamps are particularly useful, while a combination of D bulb and H bulb can also be suitably applied. A further example of a suitable source of UV radiation is a mercury-vapour lamp such as a 300 W/inch (300 W/2.5 cm) UV mercury medium pressure lamp from American UV Company.

Upon curing of a curable composition as described herein, it was found that also new block copolymers are formed. Thus, the gel permeation chromatogram of cured block copolymers contained higher molecular weight species than originally present prior to curing. Without wishing to be bound to a particular theory, it would appear that radically polymerisable monomer, in particular acrylate monomers, oligomers and/or polymers are grafted onto polymer blocks A, m particular poly (styrene) blocks A.

Therefore, the present invention further relates to a block copolymer containing at least two polymer blocks A, and at least one polymer block B, wherein polymer block B is primarily an aliphatic elastomeπc polymer block and polymer block A is primarily a monovmyl aromatic hydrocarbon polymer block further containing polymerised radically polymerisable compound, which block copolymer is obtainable by curing a curable polymeric composition as described herein.

The cured polymeric composition can be used many end-use applications where e.g. a better temperature resistance is required and/or there is a need for easier processing of the polymeric composition.

Typical end-use applications include oil gels, adhesives, sealants, coatings, printing plates, polymer modification and elastomeπc compounds for a variety of applications. The low viscosity of the curable polymeric composition opens up a whole new array of possible products. For example, it should now be possible to provide a solvent-less transparent DIY sealant that comprises the curable polymeric composition and a photo-initiator. The sealant is applied with shear at room temperature and the polymeric composition cures under the influence of daylight.

Therefore, the present invention further relates to articles containing the curable polymeric composition as described herein; or the cured polymeric composition (or the block copolymer) as described herein.

The invention will now be further described with reference to the following Examples . Examples

In the experiments described in the following Examples hexanediol diacrylate (HDDA) ; octyl-decyl acrylate (ODA) ; and oxyethylated phenol acrylate (EBECRYL 110) have been used as radically polymerisable compound. 651 (2 , 2-dimethoxy-l, 2-diphenylethan-l-one) is used as photo-initiator. The following table gives the solubility parameter δ for the various ingredients and the difference with the solubility parameter of polystyrene and of an ethylene/propylene rubber (EBECRYL is a trade mark) .

N.D. = not determined

Block copolymers that were used in the experiments according to the invention are described in the following table :

* PS : Polystyrene

** EB : Ethylene-Butylene block, or hydrogenated polybutadiene block

*** EP : Ethylene-Propylene block, or hydrogenated polyisoprene block.

Example 1

In the experiments described in this example four types of styrenic block copolymers were compared. Block copolymer bcA has been described herein above. KRATON D-1101 is a polystyrene-polybutadiene-polystyrene block copolymer (SBS) (KRATON is a trade mark) . KRATON D-1107 is a polystyrene-polyisoprene-polystyrene block copolymer (SIS). KRATON G-1750 is a (Ethylene-Propylene ) n star polymer of a molecular weight above 160,000 gr/mole containing no A block. 100 parts by weight of each formulation (see Table I) was dissolved in 25 parts by weight of toluene. The resulting homogeneous mix was poured into a siliconised tray and dried for 3 days in air at room temperature and 2.5 days at 30 °C in an oven under vacuum. The resulting cast film of a thickness close to 1.5mm was then irradiated by 20 passes at 10 m/minute under a 300 W/2.5cm (300 W/inch) UV lamp. The cured cast films were then immersed in toluene for 24 hours. The resulting systems were filtered with 10 mesh filters. The filtrate, if any, (a swollen gel) was dried and weighed.

The drop point temperature was measured by placing the sample in a cup containing a hole at the bottom which is 0.28 cm in diameter. The sample was heated at a rate of 5 °C/min. The temperature at which a drop of sample flows through the hole of the cup is called the drop point temperature. A very similar test is described in ASTM D3104-87: test method for softening point of pitches (Metier softening point method) . In order to measure the drop point of cured systems, the uncured system were put in cups and the cups were then irradiated in the same way as the films.

Table I

# = not according to the invention

(%w)^a : gel content after curing : (dried gel weight/ cured film weight) *100

It can be seen in Table I that the cured polymeric composition 1/1 and 1/6 according to the invention, containing a hydrogenated styrenic block copolymer, does not form a macroscopically visible insoluble gel after curing, demonstrating that the cured polymeric composition according to the invention is still thermoplastic. The comparative experiment 1/4, when compared with experiments 1/5 and 1/6 demonstrates the necessity of block A in the saturated block copolymer structure to observe improved temperature performance after curing. Experiment 1/5 demonstrates in addition the possibility to obtain a cured thermoset system, with cross-links via the A blocks, while still having all the advantages of the saturated B blocks compared to unsaturated systems as presented in the comparative experiments 1/2 and 1/3. Example 2

In this example two experiments with curable polymeric compositions according to the invention containing at least partially compatible radically polymerisable compounds are compared with two comparative experiments. In the curable polymeric composition of comparative experiment II/3 a "B block" compatible radically polymerisable compound is used and the comparative experiment II/4 is a polymeric system without radically polymerisable compound. The composition of the polymeric compositions and the drop point temperature results are given in Table II.

Experiment II/l demonstrates the lower drop point temperature experienced before curing compared to the non modified comparative experiment II/4. In addition, both II/l and II/2 demonstrate the higher temperature resistance obtained after curing compared to both II/3 and II/4, while keeping the cured system thermoplastic. Experiments : Table II

# = not according to the invention. Example 3

In this example it is demonstrated that a minimum of radical polymerisable compound is required. This minimum radically polymerisable compound weight percentage is demonstrated to be 0.1 times the weight percentage of polymer blocks A, where both weight percentages are based on the total of block copolymer and radically polymerisable compound. The comparative experiment III/2, just below this limit, presents a marginal temperature improvement over the non modified system (III/l) while the experiment III/3, just above the limit, presents a significant increase in drop point compared to the non modified system (III/l) . Experiments :

Table III

# = not according to the invention.

(rpc%/pba%) * : radical polymerisable compound %w/polymer block A %w. Example 4

This example demonstrates the improved temperature resistance of a cured polymeric composition according to the invention.

The curable polymeric composition IV/2 (see table IV) was prepared as follows . The photo-mitiator was first mixed in the liquid HDDA at room temperature. Both this premix and the diluent (ONDINA N68 oil) were then ^λdry mixed' with the block copolymer powder. Finally, this premixed compound was fed into a single screw extruder and extruded twice at 140 °C.

The strands (± 1 cm diameter) were then cured via twenty passes under a 300 W/2.5 cm (300 W/mch) UV bulb at 10 m/mm . The cured strands where then cut m pieces and re-fed into the single screw extruder at 180 °C. The polymeric composition IV/1 was prepared in an analogous fashion, but no HDDA was added and the polymeric composition was not cured.

A sample of the uncured and the cured reprocessed polymeric compositions were analysed via Dynamic Mechanical Thermal Analysis (RDAII rheometer from Rheometrics) . The test conditions were: a temperature sweep at 5 °C/min ranging from -100 °C to 200 °C at 10 rad/s in a plate/plate 2 mm gap geometry. The following table IV summarizes the key characteristics of the measured curves:

Table IV

# = not according to the invention.

The temperature at which tanδ = maximum (B phase Tg) is identical for both polymeric compositions. This indicates that the cured radically polymerised compound (HDDA) is not compatible with the rubber phase (the "B" polymer block phase) .

However, the elastic modulus (G' ) at room temperature (corresponding to the tanδ minimum) is more than double in IV/2 indicating the cohesion reinforcement induced by the cured radically polymerised compound. The crossover point temperature referred to in the table as "maximum temperature at which tanδ = 1" clearly indicates a large increase of the elastic temperature resistance of IV/2 compared to IV/1. The crossover point temperature is the transition temperature above which the viscous behaviour of the cured polymeric composition is predominant over the elastic behaviour.

While the cured polymeric composition IV/2 is predominantly elastic when measured by DMTA even at 200 °C, it was easily reprocessed at 180 °C in the extruder, demonstrating its thermoplasticity . Example 5

In this example the temperature resistance of various hot-melt systems was compared. 100 parts of block copolymer bcA was hot-melt mixed with 100 parts of diluent (ONDINA N68) and then modified by hot-melt extruder mixing with 30 parts of various reinforcing resins (see table V) . Formulation V/l was UV cured, as described in Example 4, experiment IV/2) . The formulations were then compressed at 230 °C to obtain a homogeneous 6 mm thick sample at rest (DIN 53517) . The initial thickness (dO) was measured precisely. The samples were then compressed to a thickness of 4.50 mm (dl) for 24 hours at 70 °C. Subsequently the samples were allowed to recover at room temperature for 30 minutes. Their final thickness was measured (d2). The percentage of recovery is then expressed as 100* (d2-dl) / (dO-dl) which is equivalent to 100 - compression set percentage. At 70 °C, formulation V/l according to the invention is found to be more elastic (better recovery) than all other systems and far better than the unmodified reference V/5. Table V

ENDEX 155 is an endblock resin of polymerised alpha methyl styrene

PMMA is polymethyl methacrylate

PBT is polybutylene terephthalate

Example 6

Formulations VI/1, VI/2 and Vl/3 were made by blending in a glass container at 140-150 °C the various ingredients. The order-disorder transition temperature

(ODT) , was measured via DMTA by the abrupt drop in the isochronal curve plot of G' (0.3 Hz) versus temperature. The curing was obtained by passing the formulation

(sitting in the drop point cup) 20 times under a 300 W/inch (300 W/2.5 cm) UV bulb at 10 m/min.

VI/3 and VI/3b were first radiation cured at a temperature of about 140 °C (above its order-disorder transition temperature of 105 °C) , whereas VI/2 and VI/2b were first radiation cured at room temperature (below its order-disorder transition temperature) . Both VI/2b and VI/3b were cured a second time at room temperature. The results are set out in Table VI . Table VI

# = not according to the invention

The drop point temperature of VI/2 and VI/3 prior curing was 81 °C, which is lower than the comparative formulation VI/1 without HDDA. This demonstrates that prior to curing the HDDA acts as a solvent for the polystyrene domains. After curing the drop point temperature of VI/1 is unchanged, whereas the drop point temperature of VI/2 is increased by 25 °C to reach a value 17 °C above the reference VI/1 showing the effective reinforcing effect. VI/2 was thermoplastic even after curing. Repeated curing at room temperature (VI/2b) did not result m a further increase of the drop point temperature .

VI/3 was cured above the order-disorder transition temperature (ODT) and the increase in drop point was only 9 °C. The reached final drop point temperature is again similar to the drop point of the unmodified reference VI/1. Like VI/2, VI/3 was thermoplastic after curing. A second curing step at room temperature, below the ODT, did not result in any increase of the drop point temperature (see VI/3b) .

Without wishing to be bound by a particular theory, it would appear that above the ODT the HDDA is dispersed, like the polystyrene polymer blocks, in the aliphatic phase where it cross-links without substantially reinforcing the polystyrene polymer blocks.

Claims

C L A I M S

1. Curable polymeric composition comprising

(i) a thermoplastic block copolymer containing at least two polymer blocks A separated by at least one polymer block B, wherein polymer block A is primarily a poly (monovinyl aromatic hydrocarbon) block or primarily a poly(C3~C7 alkenoic acid ester) block, and polymer block B is primarily an aliphatic elastomeric polymer block;

(ii) a radically polymerisable compound that is at least partially compatible with polymer blocks A, and not compatible with polymer block B, wherein the weight percentage of radically polymerisable compound is in the range from 0.1 to 3 times the weight percentage of polymer blocks A, where both weight percentages are basis the total of block copolymer and radically polymerisable compound; and

(iii) a radical initiator that is at least partially compatible with the polymer blocks A and/or the radically polymerisable compound, and not compatible with polymer block B.

2. Curable polymeric composition as claimed in claim 1, wherein the radical initiator is a photo-initiator.

3. Curable polymeric composition as claimed in claim 1 or 2, wherein the radically polymerisable compound is compatible with polymer blocks A.

4. Curable polymeric composition as claimed in any one of the preceding claims, wherein the radically polymerisable compound after polymerisation is still compatible with polymer blocks A.

5. Curable polymeric composition as claimed in any one of the preceding claims, wherein the block copolymer, polymer block B is a hydrogenated poly (conjugated diene) block.

6. Curable polymeric composition as claimed in any one of the preceding claims, wherein the block copolymer, polymer block A is a poly (monovinyl aromatic hydrocarbon) block .

7. Curable polymeric composition as claimed in any one of the preceding claims, wherein the block copolymer has the structure A-B-A', A-B-A' -B', (A-B)nX or (A-B)pX(B' (-A' ) r)q, wherein X is the residue of a coupling agent; A' and B' are polymer blocks of the same or different molecular weight as polymer blocks A and B respectively and polymer blocks A' and B' are selected from the same group of chemical compounds as polymer blocks A and B respectively; n > 2; p > 1; r is 0 or 1; q > 1; and (r*q + p) > 2.

8. Curable polymeric composition as claimed in claim 7, wherein n < 100 and (p + q) < 100.

9. Curable polymeric composition as claimed in any one of the preceding claims, further comprising an aliphatic or cycloaliphatic diluent, compatible with polymer blocks B, but not with polymer blocks A or with the radically polymerisable compound.

10. Curable polymeric composition as claimed in any one of the preceding claims further comprising a tackifying resin compatible with polymer blocks B.

11. Curable polymeric composition as claimed in any one of the preceding claims further comprising a polyolefin.

12. Curable polymeric composition as claimed in any one of the preceding claims, wherein the weight percentage of radically polymerisable compound is less than 2.5 times the weight percentage of polymer blocks A, wherein both weight percentages are basis the total of block copolymer and radically polymerisable compound.

13. Curable polymeric composition as claimed in any one of the preceding claims, wherein the radically polymerisable compound is chosen from the group of styrene, C -C4~alkylstyrene, Cχ-C4-dialkylstyrene, compounds containing C3-C7 alkenoic acid ester groups, divinyl benzene, and divinyl C1-C4 alkyl benzene.

14. Curable polymeric composition as claimed in claim 13, wherein the radically polymerisable compound is a compound containing C3-C7 alkenoic acid ester groups of formula A,

wherein R_ is hydrogen or a C -C4 alkyl group; R₂ is a C -C3 alkane group; R3 is a Cχ-Cg arene, alkane or cycloalkane group; R4 is hydrogen or a methyl group; a is 0 or 1; and b is an integer in the range from 1 to 6.

15. Curable polymeric composition as claimed in claim 14, wherein the compound containing C3-C7 alkenoic acid ester groups is selected from those compounds represented by formula A in which a is 0 and b is an integer in the range from 1 to 4.

16. Curable polymeric composition as claimed in any one of claims 1 to 12 that is thermoplastic after curing, wherein the radically polymerisable compound is chosen from monovinyl containing compounds.

17. Curable polymeric composition as claimed in claim 16 that is thermoplastic after curing, wherein the radically polymerisable compound is chosen from the group of styrene, Cχ-C4-alkylstyrene, Cχ-C4-dialkylstyrene, and saturated compounds containing one C3-C7 alkenoic acid ester group.

18. Curable polymeric composition as claimed in any one of claims 1 to 12 that is thermoplastic after curing, wherein the radically polymerisable compound is chosen from divinyl or polyvinyl containing compounds; the weight percentage of polymer block A, radically polymerisable compound, radical initiator, and any end-block resin and polymer block A compatible oil and resin is not more than 25% by weight basis the total block copolymer and auxiliaries that are compatible with either the A or the B polymer blocks; and moreover the total weight average molecular weight of the block copolymer is not more than 125,000.

19. Curable polymeric composition as claimed in any one of claims 1 to 12 that is thermoset after curing, wherein the radically polymerisable compound is chosen from divinyl or polyvinyl containing compounds; wherein the total weight average molecular weight of the block copolymer is more than 160,000 if the weight percentage of polymer block A, radically polymerisable compound, radical initiator, and any end-block resin and polymer block A compatible oil and resin is not more than 25% by weight basis the total block copolymer and auxiliaries that are compatible with either the A or the B polymer blocks .

20. Curable polymeric composition as claimed in claim 2, wherein the photo-initiator is selected from the group consisting of:

(1) a benzophenone of the general formula (I)

wherein R1 to R" independently represent hydrogen or an alkyl group having from 1 to 4 carbon atoms, preferably methyl, and wherein R^ and/or R^ have the same meaning as R! to R" or represent in addition alkoxy or 1 to 4 carbon atoms and wherein n has a value of 0, 1, or 2, optionally in combination with at least one tertiary amine, (2) a sulphur-containing carbonyl compound, wherein the carbonyl group is directly bound to at least one aromatic ring and is preferably of the general formula II wherein R^, R10^ and RU each may represent hydrogen, alkyl of

1 to 4 carbon atoms, or an alkylthio having 1 to 4 carbon atoms, and

(3) mixtures of (1) and (2) .

21. Curable polymeric composition as claimed in claim 2 or 20, wherein the photo-initiator is present in an amount from 0.1 to 5 parts by weight per 100 parts by weight of radically polymerisable compound.

22. Curable polymeric composition as claimed in any one of the preceding claims, wherein polymer blocks A are poly (styrene) blocks and the radically polymerisable compound has a solubility parameter in the range from 8.87 to 9.52.

23. Process for the preparation of a cured polymeric composition, which comprises radically polymerising the radically polymerisable compound in the curable polymeric composition as claimed in any one of the preceding claims at a temperature below the order-disorder transition temperature of the polymeric composition.

24. Process for the preparation of a cured polymeric composition as claimed in claim 23, which process comprises radically polymerising the radically polymerisable compound in the presence of a photo- initiator by actinic radiation.

25. Process for the preparation of a cured polymeric composition as claimed in claim 23, which process comprises radically polymerising the radically polymerisable compound in the presence of a thermal radical initiator.

26. Cured polymeric composition, obtainable by curing a curable polymeric composition as claimed in any one of claims 1 to 22.

27. Block copolymer containing at least two polymer blocks A, and at least one polymer block B, wherein polymer block B is primarily an aliphatic elastomeric polymer block and polymer block A is primarily a monovinyl aromatic hydrocarbon polymer block further containing polymerised (radically polymerisable compound) , obtainable by curing a curable polymeric composition according to the process as claimed in any one of claims 23-25.

28. Thermoplastic blend comprising from 125 to 2500 parts by weight of a polyolefin per 100 parts by weight of a curable polymeric composition as claimed in any one of claims 1 to 22 or a cured polymeric composition as claimed in claim 26.

29. Articles containing the curable polymeric composition of any one of claims 1 to 22; or the cured polymeric composition of claim 26; or the block copolymer of claim 27; or the thermoplastic blend of claim 28.