Rubber-reinforced vinylaromatic (CO)polymers and process for the preparation thereof

Abstract

A rubber-reinforced ethylene aromatic (co)polymer comprising: (a) a polymer matrix comprising at least one ethylene aromatic monomer and at least one comonomer; (b) rubber particles obtained by a continuous mass process from functionalized low-cis polybutadiene rubber (LCBR) dispersed therein, characterized by the following facts: (i) the average volume diameter of the rubber particles is between 0.25 μm and 0.37 μm, preferably between 0.26 μm and 0.36 μm, more preferably between 0.27 μm and 0.35 μm; (ii) the volume of the rubber particles having a diameter greater than 0.40 μm relative to the total volume of the dispersed rubber particles is between 20% and 50%, preferably between 25% and 45%, more preferably between 30% and 40%; (iii) The ratio of encapsulated rubber particles to unencapsulated rubber particles (including encapsulated particles / unencapsulated particles) is between 0.9 and 1.9, preferably between 1.0 and 1.8, and more preferably between 1.2 and 1.7. The aforementioned rubber-reinforced ethylene aromatic (co)polymers possess high aesthetic properties, particularly in terms of gloss and gloss sensitivity; and high mechanical properties, particularly in terms of impact resistance and puncture resistance. The aforementioned rubber-reinforced ethylene aromatic (co)polymers can be advantageously used in a variety of applications, such as injection molding.

Description

Technical Field

[0001] This invention relates to a rubber-reinforced ethylene aromatic (co)polymer.

[0002] More specifically, the present invention relates to a rubber-reinforced ethylene aromatic (co)polymer comprising: (a) a polymer matrix comprising at least one ethylene aromatic monomer and at least one comonomer; and rubber particles obtained by a continuous mass process from a functionalized low-cis polybutadiene rubber (LCBR) dispersed therein, having specific characteristics in terms of size and morphology.

[0003] The aforementioned rubber-reinforced ethylene aromatic (co)polymers have high aesthetic properties, particularly in terms of gloss and gloss sensitivity; and high mechanical properties, particularly in terms of impact resistance and puncture resistance.

[0004] The aforementioned rubber-reinforced ethylene aromatic (co)polymers can be advantageously used in a variety of applications, such as injection molding.

[0005] A further objective of the present invention is a method for preparing the aforementioned rubber-reinforced ethylene aromatic (co)polymer. Prior Technology

[0006] It is known that the balance between the aesthetic and mechanical properties of rubber-reinforced ethylene aromatic (co)polymers depends on the rubber concentration in the finished (co)polymer and the average volume diameter distribution of the rubber particles dispersed in the polymer matrix.

[0007] For example, to obtain a rubber-reinforced ethylene aromatic (co)polymer, such as an acrylonitrile-butadiene-styrene (ABS) copolymer, with good mechanical properties and high surface gloss, it is necessary that the rubber concentration in the copolymer is higher than 13% by mass and that the rubber particles have an average volume diameter of less than 0.5 micrometers and a wide volume diameter distribution between 0.1 and 0.5 micrometers, preferably bimodal. If any of these parameters are not met, the desired mechanical properties and surface gloss will not be obtained, and therefore the resulting (co)polymer will be unsuitable for the final application. For example, a rubber-reinforced ethylene aromatic (co)polymer with 15% by mass of rubber particles having an average particle volume diameter of 0.2 micrometers and a narrow volume diameter distribution between 0.1 and 0.3 micrometers will have high surface gloss but will not have good mechanical properties.

[0008] The morphology of the rubber particles dispersed in the polymer matrix is ​​also very important in defining the aesthetic and mechanical properties of the rubber-reinforced ethylene aromatic (co)polymer. In order to precisely adjust these properties, the elastomeric phase (i.e., rubber particles) dispersed in the polymer matrix needs to include particles with small to medium volume diameters (typically less than 0.3 micrometers) and spherical or capsule-shaped morphologies (containing a single inclusion), as well as particles with larger average volume diameters (between 0.3 and 0.5 micrometers) and "salami" (or multiple inclusion) morphologies.

[0009] For example, EP Patent 0390781 and US Patent 4,713,420 relate to rubber-modified acrylonitrile-butadiene-styrene (ABS) copolymers comprising three different types of rubber particles. Specifically, the rubber particles are: 1) rubber particles with a small average volume diameter between 0.05 μm and 0.25 μm, manufactured by an emulsion method; 2) rubber particles with a large average volume diameter between 0.4 μm and 2 μm, manufactured by an emulsion method; and 3) rubber particles with a large average volume diameter between 0.5 μm and 10 μm, manufactured by a bulk method. In particular, these patents show how rubber particles with an average volume diameter greater than 0.5 μm promote the mechanical properties of the copolymer, but this is detrimental to its aesthetic properties, especially its gloss. Therefore, to ensure a proper balance between mechanical and aesthetic properties, in these patents, the rubber-modified acrylonitrile-butadiene-styrene (ABS) copolymer is obtained by precisely mixing multiple components, particularly multiple rubber particles based on their average volume diameter and morphology. The aforementioned patented rubber-modified acrylonitrile-butadiene-styrene (ABS) copolymer is believed to have an excellent balance between aesthetic and mechanical properties.

[0010] U.S. Patent 6,211,298 relates to a modified rubber-modified polymer composition comprising: (a) a continuous phase matrix comprising an interpolymer of a monoethylene aromatic monomer and an ethelated unsaturated nitrile monomer; and (b) discrete rubber particles dispersed in the matrix at a weight of 5% to 40% by weight relative to the total weight of the polymer composition, wherein the dispersed rubber particles comprise: (1) at least 33% by weight of particles manufactured by a bulk method and having an average volume diameter relative to the total rubber content. (1) rubber particles with a volume diameter between 0.15 micrometers and 0.40 micrometers; (2) rubber particles with a small average volume diameter between 0.05 micrometers and 0.30 micrometers, manufactured by an emulsion method, relating to the total rubber content of 15% to 67% by weight; and (3) rubber particles with a large average volume diameter greater than 0.30 micrometers and up to 2.0 micrometers, manufactured by an emulsion method, relating to the total rubber content of 0% to 35% by weight; wherein the rubber particles have an average light absorption ratio of less than 1.4. The aforementioned composition, which includes a high percentage of bulk-manufactured rubber particles with small to medium volume diameters, is believed to be less expensive and able to maintain excellent gloss and good impact properties. Compared with similar compositions having similar gloss and gloss sensitivity, the aforementioned composition is also believed to have improved thermal and color stability.

[0011] As is known in the art, rubber particles can be manufactured by two types of methods: emulsion polymerization and continuous bulk polymerization.

[0012] It is known that in emulsion polymerization methods, the size of the rubber particles is arbitrarily adjusted in an early stage of the process by free radical polymerization of butadiene in an aqueous emulsion. Then, the rubber particles with the defined size are grafted with styrene and acrylonitrile. The product of this reaction is called a grafted acrylonitrile-butadiene-styrene (ABS) copolymer, characterized by a high polybutadiene concentration. The presence of this chemically grafted styrene-acrylonitrile (SAN) copolymer is fundamentally important for the compatibility of polybutadiene in the styrene-acrylonitrile (SAN) copolymer, as the two polymers are incompatible. The emulsion manufacturing method of this acrylonitrile-butadiene-styrene (ABS) copolymer includes the step of compounding the grafted acrylonitrile-butadiene-styrene (ABS) copolymer with separately manufactured styrene-acrylonitrile (SAN) copolymer to obtain the desired product. More details about this emulsion polymerization method can be found, for example, in Bouquet G.'s "Ruber Particle Formation in Mass ABS, Modern Styrenic Polymers: Polystyrenes and Styrenic Copolymers" (2003), edited by J. Scheirs and DB Priddy in Wiley & Sons, Chapter 14, pp. 305-319.

[0013] On the other hand, in this continuous bulk polymerization method, the formation of rubber particles dispersed in the matrix begins with a solution of polybutadiene dissolved in a mixture of monomer (styrene) and diluent (normally ethylbenzene). A second monomer (acrylonitrile) is added to the solution only before the continuous bulk polymerization reaction. This precaution is necessary because the presence of acrylonitrile at the temperature at which the rubber dissolves will cause the rubber to precipitate. Once the reaction mixture has been prepared, it is subjected to free radical polymerization: when this free radical polymerization reaction proceeds, styrene-acrylonitrile (SAN) copolymer segments are formed in the polybutadiene-monomer-diluent mixture of the main polymer phase, polybutadiene. At a certain degree of monomer inversion, the volume of the polybutadiene phase in the reaction system will be equal to the volume of the styrene-acrylonitrile (SAN) copolymer phase: this moment is called phase inversion. The monomer conversion occurs during the formation of the styrene-acrylonitrile (SAN) copolymer. In the reaction mixture, the main phase is composed of the styrene-acrylonitrile (SAN) copolymer, while the dispersed phase is composed of polybutadiene particles dispersed within the main phase of the styrene-acrylonitrile (SAN) copolymer. Immediately following this phase inversion, the diameter and morphology of the dispersed rubber particles are defined.

[0014] It is also known that the main parameters affecting the diameter and morphology of the rubber particles are: - Shear stress (or "shear") imposed on the reaction mixture; - The interfacial tension between the two polymer phases [polybutadiene and styrene-acrylonitrile (SAN) copolymer] present in the reaction mixture; - The viscosity ratio between the polybutadiene phase and the styrene-acrylonitrile (SAN) copolymer phase.

[0015] Furthermore, in this continuous bulk polymerization method, to obtain an acrylonitrile-butadiene-styrene (ABS) copolymer comprising rubber particles with an average volume diameter of less than 0.5 micrometers and to maximize the gloss and mechanical properties of the final product, the following is required: - By mechanical stirring, the shear stress (shear) imposed on the reaction mixture is maximized; - Appropriately adjust the formation of the graft copolymer to precisely adjust the interfacial tension; - To minimize the viscosity ratio between the polybutadiene phase and the styrene-acrylonitrile (SAN) copolymer phase, it is necessary to use a low-viscosity rubber and maximize the viscosity of the styrene-acrylonitrile (SAN) copolymer formed during the reaction.

[0016] In the literature, there are various technical solutions for synthesizing acrylonitrile-butadiene-styrene (ABS) copolymers using rubber particles with an average particle volume diameter of less than 0.5 micrometers via continuous bulk polymerization, which provides a combination of using low-viscosity rubber to maximize the grafting reaction.

[0017] It is known that, in the early stages of this polymerization reaction, at temperatures below 115°C, the use of a difunctional radical polymerization initiator results in an increase in both styrene-acrylonitrile (SAN) copolymers grafted onto polybutadiene and high molecular weight styrene-acrylonitrile (SAN) copolymer phases. However, for the low weight average molecular weight (Mw) polybutadiene concentration greater than 9% in the initial reaction mixture and the high weight average molecular weight (Mw) styrene-acrylonitrile (SAN) copolymer formed before phase inversion, the condition for partial crosslinking of the elastomeric phase (i.e., rubber particles) is met because the polymer chains of the styrene-acrylonitrile (SAN) copolymer can be grafted onto two polymer chains of two distinguishable polybutadiene rubber particles.

[0018] For example, U.S. Patent 5,414,045 relates to a composition obtained by a continuous bulk polymerization method through the reaction of a continuous phase comprising an ethylene aromatic monomer, an unsaturated nitrile monomer, and a diene polymer rubber dissolved in the monomer. The composition comprises a graft copolymer and a free rubber copolymer. The graft copolymer comprises a diene rubber substrate and an ethylene aromatic / unsaturated nitrile copolymer grafted onto the substrate. The rubber substrate has an average particle diameter of less than 0.3 micrometers, and has both internal and external surfaces with a cellular morphology. The cellular morphology is defined as a network having a spherical surface and including a rubber film encapsulated within the ethylene aromatic / unsaturated nitrile copolymer. The unsaturated ethylene aromatic / nitrile copolymer is grafted into both the internal and external surfaces of the rubber substrate. The composition, measured at 60° using a Grader gloss meter, has a gloss level greater than 90%. The polymerization reaction is carried out in a plug flow reactor (PFR), and the reaction mixture leaving the reactor is fed into a continuous stirred tank reactor (CSTR) with a higher content of ethylene aromatic / unsaturated nitrile copolymer to complete the reverse inversion.

[0019] US Patent 7,132,474 relates to a continuous bulk method for preparing an acrylonitrile-butadiene-styrene (ABS) copolymer, comprising the following steps: a) preparing a solution comprising styrene monomer and acrylonitrile monomer by adding 5%-10% by weight of a mixture of styrene monomer and acrylic monomer to a reaction solvent; b) preparing a polymerization solution by dissolving butadiene rubber in the solution comprising styrene monomer and acrylonitrile monomer; c) performing polymerization by injecting the solution prepared in step b) and an initiator in a grafting reactor; performing polymerization by adding, in a reverse-rotation reactor, 90%-95% by weight of the reaction mixture obtained in step c) relative to the total weight of the reaction mixture of styrene monomer and acrylic monomer; and e) further polymerizing the reaction mixture obtained in step d) at 130°C-160°C. The aforementioned composition is believed to have excellent impact resistance and excellent gloss.

[0020] However, the aforementioned methods are complex and involve the use of a continuous stirred tank reactor (CSTR), which is generally not recommended for the manufacture of acrylonitrile-butadiene-styrene (ABS) copolymers because they require frequent cleaning and cannot guarantee the quality of the final product.

[0021] Another way to increase the graft polymer concentration in the manufacture of rubber-reinforced styrene (co)polymers, such as impact-resistant polystyrene (HIPS), via a continuous bulk method is by using diblock rubber.

[0022] It is known that in the manufacture of high-impact polystyrene (HIPS), a styrene-polybutadiene block copolymer, comprising 60% by weight of polybutadiene, is fed into the elastomer phase to obtain rubber particles with an average volume diameter of less than 0.5 micrometers (single-encapsulation) and high gloss. Unfortunately, polybutadiene-styrene-acrylonitrile block copolymers (polybutadiene-SAN) cannot be used in the synthesis of acrylonitrile-butadiene-styrene (ABS) copolymers because acrylonitrile cannot be anionicly polymerized.

[0023] However, the reported known techniques emphasize and advocate the "in-situ" formation of the grafted polybutadiene-styrene-acrylonitrile (polybutadiene-SAN) copolymer during the polymerization of the polybutadiene, styrene, and acrylonitrile mixture. To emphasize the reaction between the polybutadiene and the mixture of styrene and acrylonitrile monomers, a rubber whose molecular structure includes active radical sites that can be activated at the temperatures used in the free radical polymerization method is used.

[0024] For example, EP Patent 1,592,722 relates to a bulk / solution method for manufacturing a polymeric rubber modified with ethylene aromatic monomers using a functionalized rubber. This method involves polymerizing the ethylene aromatic monomers in the presence of a rubber via a linear process using one or more polymerization reactors. The rubber comprises a functionalized styrene-butadiene block copolymer having: a) a solution viscosity (5% in styrene, at 20°C) of 5 cps to less than 50 cps; and b) each rubber polymer chain having at least one functional group capable of controlling free radical polymerization to form the grafted rubber particles and disperse them in a matrix containing the polymerized ethylene aromatic monomers with a wide single-mode size distribution, and wherein the rubber is present in an amount between 5% by weight and 25% by weight relative to the total weight of the polymer mixture. The modified polymeric rubber thus obtained is believed to have high gloss and high hardness.

[0025] U.S. Patent 7,115,684 relates to a rubber-modified polymer composition obtained by continuous bulk polymerization, comprising: a matrix consisting of a continuous phase comprising a polymer of a monoethylene aromatic monomer and selectively, vinylated unsaturated nitrile monomers; and discrete rubber particles dispersed in the matrix, the rubber particles being manufactured from a rubber component comprising 5% to 10% by weight of a functionalized diene rubber, wherein each rubber polymer chain of the diene rubber has at least one functional group capable of controlling free radical polymerization; wherein the composition is further characterized by: a) the average volume diameter of the rubber particles being approximately 0.15 micrometers to 0.35 micrometers; the total volume of the rubber phase relative to the total weight of the matrix and the rubber particles being 12% to 45% by weight; c) the portion of the rubber phase having rubber particles with an average volume diameter greater than 0.40 micrometers being between 2% and 20%; and d) the crosslinked rubber component being at least 85% by weight relative to the total weight of the rubber particles. The aforementioned components are believed to have high gloss and high gloss sensitivity, while maintaining good hardness properties.

[0026] In the aforementioned EP patent 1,592,722 and US patent 7,115,684, the rubber, whose each polymer chain is functionalized with at least one functional group that promotes the formation of graft copolymers, is obtained by anionic polymerization of polybutadiene and styrene. The termination reaction of this anionic reaction is carried out using a compound containing a nitro functional group (i.e., an organic compound containing a nitrogen-oxygen bond) so that the styrene-butadiene rubber (SBR) includes this group as the polymer chain terminator. When the rubber is used in a continuous bulk polymerization method for the manufacture of acrylonitrile-butadiene-styrene (ABS) copolymers, the nitro functional group dissociates, generating terminal radical sites on the styrene-butadiene rubber chain (SBR) that can react with the styrene and acrylonitrile monomers, thereby forming a grafted polybutadiene-styrene-acrylonitrile copolymer (polybutadiene-SAN) "in situ". The description of the rubber synthesis method using polymer chain terminals including nitro groups is described, for example, in U.S. Patent 5,721,320, cited in the aforementioned reported EP Patent 1,592,722 and U.S. Patent 7,115,684.

[0027] However, the industrial applications of the aforementioned EP patent 1,592,722 and US patent 7,115,684 are limited by the uncommercial availability of the functionalized rubber. Furthermore, to minimize the viscosity ratio between the polybutadiene phase and the styrene-acrylonitrile (SAN) matrix (which is another fundamental parameter for obtaining rubber particles with an average volume diameter of less than 0.5 micrometers), functionalized styrene-butadiene block copolymers are used in these patents. This need stems precisely from the method used in these patents, which in fact provides a rubber solution prepared in a monomer mixture that must undergo the polymerization process. Industrially, the preparation of this mixture requires the polybutadiene to undergo a process of dissolving in the monomer mixture: therefore, it is necessary to manufacture the polybutadiene, then subject it to a finishing process (removal of the solvent phase in which it has been synthesized), and then milling it to undergo the dissolution process. When the viscosity of the rubber is particularly low, as described in the aforementioned patents, this finishing step and subsequent milling step are technically difficult, if not impossible. Therefore, it is necessary to structurally modify the rubber by incorporating polystyrene blocks into the polymer chain to increase the rubber's own viscosity and allow for the completion phase and subsequent grinding.

[0028] However, as described in U.S. Patent 5,721,320 reported above, the use of styrene-butadiene rubber (SBR) in the synthesis of that acrylonitrile-butadiene-styrene (ABS) copolymer would be economically unfavorable for two reasons : the inherent cost of styrene-butadiene rubber (SBR);and forced to feed more styrene-butadiene rubber (SBR) in the fabrication method of this acrylonitrile-butadiene-styrene (ABS) copolymer due to comparison with polybutadiene rubber. In fact, the properties of the acrylonitrile-butadiene-styrene (ABS) copolymer are dependent on the polybutadiene concentration in the final product: because in that styrene-butadiene block rubber (SBR), the polybutadiene content is less than 100%, it is necessary to feed more styrene-butadiene (SBR) rubber blocks to achieve the desired polystyrene-butadiene-butadiene-butadiene concentration in the acrylonitrile-butadiene (SBR) rubber block. Finally, the fact that needs to be taken into account is the need to provide a mixture of functionalized styrene-butadiene rubber (SBR) and unfunctionalized rubber should it be necessary to adjust the amount of grafted copolymer produced “in situ” using that rubber. In fact, as reported in the foregoing patents EP 1,592,722 and US 7,115,684, the functionalized rubber must include at least one functional group per rubber polymer chain. If the amount of the grafted copolymer formed by the functionalized rubber is used in this manner in excess, it is necessary (as also mentioned in an embodiment of the previously mentioned patent) to reduce the active site concentration in the reaction mixture by resorting to the addition of the unfunctionalized rubber, wherein the rubber chain includes on average a number of less than one active site. The use of two types of rubber includes complicating the manufacturing method and increasing manufacturing costs.

[0029] Other useful methods of obtaining polymers functionalized with nitrosyl groups that can facilitate subsequent grafting reactions are also known.

[0030] For example, U.S. Patent 6,525,151 relates to a method of preparing a grafted polymer in which a stable nitroxide radical is grafted into the polymer in that first step A) comprising heating the polymer with the stable nitroxide radical ( NO·); and in that second step B), the grafted polymer of the step A) is heated in the presence of the vinylized unsaturated monomer or oligomer to a temperature at which the nitrosyl-polymer bond breaks and the vinylized unsaturated monomer or oligomer begins to polymerize on the polymer radical; the temperature is maintained for continuous polymerization and subsequent cooling to a temperature below 60°C.

[0031] The functionalization method described in the aforementioned U.S. Patent 6,525,151 is highly effective and allows for arbitrary adjustment of the amount of nitro bonds formed in a single rubber polymer chain. In cases where it is necessary to use polybutadiene polymer chains with fewer than one active site per polymer chain, the use of two rubbers (one functionalized and one unfunctionalized) is not forced. However, the functionalization method described in the aforementioned patent specifies that the functionalization reaction is carried out on molten polymer: at the industrial level, this involves an additional processing step compared to standard methods, thus increasing costs.

[0032] U.S. Patent 6,335,401 relates to a graft copolymer comprising a graft group having general formula (I): -O-PM 1-(PM 2)-T (I) in: - PM 1 represents a polymer block obtained by free radical (co)polymerization of at least one monomer M 1; - PM2 exists selectively, representing a polymer block obtained by free radical (co)polymerization of at least one monomer M2; and - T represents a stable free radical T* residue.

[0033] This (co)polymer system is synthesized by reacting a polymer (e.g., polyethylene) with ozone, and then growing it with a monomer (e.g., styrene) in the presence of stable nitro radicals. However, even this method, while extremely efficient, is difficult to apply industrially.

[0034] A method is known that is further useful in solution for obtaining polymers that can be nitrofunctionalized to promote subsequent grafting reactions.

[0035] For example, U.S. Patent 6,255,402 relates to a method for synthesizing a functionalized rubber, particularly high-impact polystyrene (HIPS), having a group capable of generating stable free radicals (e.g., nitro group). This method comprises heat-treating the elastomer in the presence of a stable free radical, a free radical initiator capable of inducing protons from an elastomer, and a solvent, and in the absence of an ethylene aromatic monomer, so that the rubber is functionalized with an average of 0.1 to 10 functional groups capable of generating stable free radicals per rubber polymer chain. Subsequently, the functionalized rubber thus obtained, such as nitro-functionalized polybutadiene, is subjected to free radical polymerization in the presence of an ethylene aromatic monomer, such as styrene, to form a grafted polybutadiene-polystyrene copolymer "in situ". The functionalization reaction is carried out by dissolving the polybutadiene in a diluent (normally ethylbenzene) used in the subsequent synthesis of high-impact polystyrene (HIPS) in the presence of a free radical initiator and a compound including a stable nitrocellulose free radical. The resulting reaction mixture is heated to a temperature sufficient to facilitate the decomposition of the free radical initiator. After the addition of styrene and additives, the functionalized rubber solution in the diluent is subjected to free radical polymerization to obtain the final high-impact polystyrene (HIPS). The final properties of the high-impact polystyrene (HIPS), in terms of balancing mechanical and aesthetic properties, are varied by modifying the amount of the free radical initiator / stable nitrocellulose free radical system in the diluent during the functionalization reaction of the rubber.

[0036] The functionalization reaction of polybutadiene in solution is an effective technique, and it also allows for arbitrary adjustment of the amount of nitro functional groups generated in a single polymer rubber chain by reacting the stable nitro radical with the polybutadiene. Therefore, in cases where it is necessary to use polybutadiene comprising fewer than one active site per rubber polymer chain, the use of two rubbers (one functionalized and one unfunctionalized) is not forced. However, this method also has drawbacks due to the maximum amount of polybutadiene achievable in the final polymer. In the embodiment reported in the aforementioned U.S. Patent 6,255,402, the functionalization reaction of the rubber is, in fact, carried out by preparing a 20% by weight polybutadiene dissolved in a diluent. The subsequent addition of styrene results in a polybutadiene concentration of 6% in the reaction, while the diluent dosage in the reaction is 24%. The amounts of these reagents are suitable for the synthesis of high-impact polystyrene (HIPS), but not for the synthesis of acrylonitrile-butadiene-styrene (ABS) copolymers. In fact, the minimum rubber concentration in acrylonitrile-butadiene-styrene (ABS) copolymers, which achieve a high balance of mechanical strength and aesthetic properties, must be at least 13%. Assuming the same amount of diluent (24%) is used, the polybutadiene concentration during the dissolution / functionalization stage of the rubber should be at least 40%. Due to the high viscosity of the rubber solution in the diluent, this rubber concentration is technically unmanageable in continuous bulk manufacturing plants. Furthermore, a 24% diluent concentration during the reaction reduces the plant's own capacity, thus increasing manufacturing costs.

[0037] Methods for producing rubber-reinforced styrene polymers in the presence of stable nitro radicals without any functionalization reaction are also known. However, in this case, a broad distribution of the average volume diameter of the rubber particles is always obtained.

[0038] For example, U.S. Patent 6,262,179 relates to a method for manufacturing a composition comprising an ethylene aromatic polymer or copolymer matrix in which rubber particles are dispersed, the method comprising a polymerization step in the presence of at least one ethylene aromatic monomer and at least one rubber, during which an inversion occurs, resulting in the formation of rubber particles; the polymerization is initiated by heat or a polymerization initiator, characterized by the presence of a stable free radical (e.g., a nitroradical) during the polymerization step, the amount of which is at least 10 ppm relative to the total amount of the ethylene aromatic monomer (e.g., styrene); and the rubber particle size distribution is broad compared to when the stable free radical is absent. In this way, a broad rubber particle size distribution is obtained, the rubber particles having an average size always higher than that required to guarantee the properties of the acrylonitrile-butadiene-styrene (ABS) copolymer a (i.e., less than or equal to 0.5 micrometers).

[0039] US Patent 6,815,500 relates to a method for preparing a composition comprising an ethylene aromatic polymer matrix including rubber particles, comprising the step of polymerizing at least one ethylene aromatic monomer in the presence of rubber, a polymerization initiator, and a stable free radical, wherein the ratio is: [F SFRx(SFR)]:[F AMOx(AMO)] The values ​​are in the range of 0.05 to 1, where FFSR and FAMO represent the functionality of the stable free radical and free radical initiator, respectively, and (SFR) and (AMO) represent the molar amounts of the stable free radical and initiator free radical, respectively. The above composition is believed to have impact resistance and / or gloss. The aforementioned polymer composition may contain at least 90% single-encapsulated rubber particles (capsules) with an equivalent diameter between 0.1 μm and 1.0 μm. Alternatively, the aforementioned composition may also include multiple encapsulated "sausage-like" particles, and preferably: 1) 20% to 60% of the total area is occupied by rubber particles consisting of rubber particles with an equivalent diameter between 0.1 μm and 1.0 μm; 2) 5% to 20% of the total area is occupied by rubber particles consisting of rubber particles with an equivalent diameter between 1.0 μm and 1.6 μm; 3) 20% to 75% of the total area is occupied by rubber particles consisting of rubber particles with an equivalent diameter greater than 1.6 μm. In all these cases, the size of the rubber particles is not suitable for ensuring a balance between the mechanical and aesthetic properties of the obtained acrylonitrile-butadiene-styrene (ABS) copolymer.

[0040] The rubber functionalization reaction can also be carried out, for example, in the presence of a free radical initiator and stable nitro radicals, in a solution including a diluent and monomers to reduce the rubber concentration at this step of the method, as described in patent applications WO 2005 / 100425 and WO 2006 / 063719. However, even in this case, the maximum concentration of polybutadiene obtainable in the final product is compatible with the synthesis phase of high-impact polystyrene (HIPS), but not with the synthesis of acrylonitrile-butadiene-styrene (ABS) copolymers.

[0041] The rubber functionalization reaction can also be carried out directly downstream of the anionic polymerization of butadiene by promoting the termination reaction of the polybutadiene chain with bromoalkane and stable nitrocellulose radicals, as described, for example, in patent application WO 2010 / 020374. However, even in this case, limitations arise because the maximum polybutadiene concentration obtainable in the final product is not compatible with the synthesis of acrylonitrile-butadiene-styrene (ABS) copolymers. Summary of the Invention

[0042] Because rubber-reinforced ethylene aromatic (co)polymers, especially acrylonitrile-butadiene-styrene (ABS) copolymers, which possess high aesthetic and mechanical properties, continue to attract considerable attention, research on novel rubber-reinforced vinyl (co)polymers continues to receive significant attention.

[0043] Therefore, the applicant raises the issue of identifying novel rubber-reinforced ethylene aromatic (co)polymers, particularly acrylonitrile-butadiene-styrene (ABS) copolymers, that possess high aesthetic properties, especially in terms of gloss and gloss sensitivity, and high mechanical properties, especially in terms of impact resistance and puncture resistance.

[0044] The applicant has now found a rubber-reinforced ethylene aromatic (co)polymer comprising: (a) a polymer matrix comprising at least one ethylene aromatic monomer and at least one comonomer; and (b) rubber particles obtained by a continuous bulk method from a functionalized low-cis polybutadiene rubber (LCBR) dispersed therein, having specific characteristics in terms of size and morphology.

[0045] The aforementioned rubber-reinforced ethylene aromatic (co)polymers possess high aesthetic properties, particularly in terms of gloss and gloss sensitivity; and high mechanical properties, particularly in terms of impact resistance and puncture resistance.

[0046] The aforementioned rubber-reinforced ethylene aromatic (co)polymers can be advantageously used in a variety of applications, such as injection molding.

[0047] Therefore, the objective of this invention is a rubber-reinforced ethylene aromatic (co)polymer comprising: (a) A polymer matrix comprising at least one ethylene aromatic monomer and at least one comonomer; (b) Rubber particles, obtained by a continuous bulk method from functionalized low-cis polybutadiene rubber (LCBR) dispersed therein, characterized by the following fact: (i) The average volume diameter of the rubber particles is between 0.25 micrometers and 0.37 micrometers, preferably between 0.26 micrometers and 0.36 micrometers, and more preferably between 0.27 micrometers and 0.35 micrometers; (ii) The volume of the rubber particles having a diameter greater than 0.40 micrometers relative to the total volume of the dispersed rubber particles is between 20% and 50%, preferably between 25% and 45%, and more preferably between 30% and 40%; (iii) The ratio of encapsulated rubber particles to unencapsulated rubber particles (including encapsulated particles / unencapsulated particles) is between 0.9 and 1.9, preferably between 1.0 and 1.8, and more preferably between 1.2 and 1.7.

[0048] For the purposes of this specification and the following claims, unless otherwise specifically indicated, the definition of a numerical range always includes the endpoints.

[0049] For the purposes of this specification and the following claims, the term "comprising" also includes the terms "essentially composed of" or "consisting of".

[0050] According to a preferred embodiment of the invention, the ethylene aromatic monomer may, for example, be selected from ethylene aromatic monomers having the general formula (I): R refers to hydrogen atoms or methyl groups; n refers to zero or an integer between 1 and 5; Y refers to halogen atoms such as, for example, chlorine, bromine, or alkyl or alkoxy groups having 1 to 4 carbon atoms.

[0051] According to a preferred embodiment of the invention, the ethylene aromatic monomer having the general formula (I) may be selected, for example, from the following: styrene, α-methylstyrene, methylstyrene, ethylstyrene, butylstyrene, dimethylstyrene; mono-, di-, tri-, tetra- and penta-chlorostyrene, bromostyrene, methoxystyrene, acetoxystyrene, or mixtures thereof. Styrene and α-methylstyrene are preferred.

[0052] For the purposes of this invention, an ethylene aromatic monomer having the general formula (I) may be used alone, or a mixture thereof may be used in up to 50% by weight with other copolymerizable monomers.

[0053] According to a preferred embodiment of the invention, the comonomer may be selected, for example, from the following: (meth)acrylic acid; C1-C4 alkyl esters of (meth)acrylic acid, such as, for example, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, isopropyl acrylate, butyl acrylate; acetamides and nitriles of (meth)acrylic acid, such as, for example, acrylamide, methacrylamide, acrylonitrile, methacrylonitrile; aceimides, such as, for example, N-phenylmaleimide; diethylene aromatic monomers, such as, for example, divinylbenzene; anhydrides, such as, for example, maleic anhydride; or mixtures thereof. Acrylonitrile and methyl methacrylate are preferred.

[0054] According to a preferred embodiment of the invention, in the rubber-reinforced ethylene aromatic (co)polymer, the polymer matrix comprising at least one ethylene aromatic monomer and at least one comonomer has a weight average molecular weight (Mw) of less than or equal to 145,000 g / mole, preferably less than or equal to 140,000 g / mole, and more preferably between 90,000 g / mole and 135,000 g / mole.

[0055] According to a preferred embodiment of the invention, in the rubber-reinforced ethylene aromatic (co)polymer, the functionalized low cis polybutadiene rubber (LCBR) is present in an amount between 5% by weight and 35% by weight, more preferably between 8% by weight and 30% by weight, and even more preferably between 10% by weight and 25% by weight.

[0056] According to a preferred embodiment of the present invention, in the rubber-reinforced ethylene aromatic (co)polymer, the rubber particles obtained by a continuous bulk method from functionalized low-cis polybutadiene rubber (LCBR) are obtained from functionalized low-cis polybutadiene rubber (LCBR) having the following characteristics: - The weight-average molecular weight (Mw) is between 40,000 g / mol and 110,000 g / mol, preferably between 50,000 g / mol and 100,000 g / mol, and even more preferably between 55,000 g / mol and 95,000 g / mol; - The polydispersity index (PDI), i.e., the ratio between the weight average molecular weight (Mw) and the number average molecular weight (Mn) (Mw / Mn), is less than or equal to 1.4, preferably less than or equal to 1.3, and more preferably less than or equal to 1.2; - The isomer composition (microstructure) of the double bonds in the rubber chain: the content of 1,4-cis units is between 10 wt% and 70 wt%, preferably between 20 wt% and 60 wt%, more preferably between 30 wt% and 50 wt%; the content of 1,4-trans units is between 20 wt% and 80 wt%, preferably between 30 wt% and 70 wt%, more preferably between 40 wt% and 60 wt%; the content of 1,2-vinyl units is between 0 wt% and 25 wt%, preferably between 0 wt% and 20 wt%, more preferably between 5 wt% and 15 wt%.

[0057] The low-cis polybutadiene rubber (LCBR) is functionalized with functional groups, wherein the functional groups can promote controlled chain radical polymerization mediated by stable nitro radicals; and each rubber polymer chain of the low-cis polybutadiene rubber (LCBR) has a number of functional groups less than or equal to 1, preferably between 0.05 and 1, more preferably between 0.2 and 0.8, and even more preferably between 0.3 and 0.7.

[0058] According to a preferred embodiment of the present invention, in the rubber-reinforced ethylene aromatic (co)polymer: - The weight average molecular weight (Mw) of the free functionalized low cis polybutadiene rubber (LCBR) is between 8,000 g / mole and 70,000 g / mole, more preferably between 10,000 g / mole and 60,000 g / mole, and even more preferably between 15,000 g / mole and 50,000 g / mole; - The degree of polymerization distribution index (PDI) of the free functionalized low-cis polybutadiene rubber (LCBR), which is the ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn), is greater than or equal to 1.3, preferably greater than or equal to 1.4, and more preferably greater than or equal to 1.5; - The isomer composition (microstructure) of the double bonds of the free functionalized low cis polybutadiene rubber (LCBR) is as follows: the content of 1,4-cis units is between 10 wt% and 70 wt%, preferably between 20 wt% and 60 wt%, more preferably between 30 wt% and 50 wt%; the content of 1,4-trans units is between 20 wt% and 80 wt%, preferably between 30 wt% and 70 wt%, more preferably between 40 wt% and 60 wt%; and the content of 1,2-vinyl units is between 0 wt% and 25 wt%, preferably between 0 wt% and 20 wt%, more preferably between 5 wt% and 15 wt%.

[0059] According to a preferred embodiment of the present invention, in the rubber-reinforced ethylene aromatic (co)polymer, the weight-average molecular weight (Mw) of the free functionalized low-cis polybutadiene rubber (LCBR) (MwLCBR l, expressed in g / moles), the average volume diameter of the rubber particles (Dvm, expressed in micrometers), the volume of rubber particles with a diameter greater than 0.40 micrometers (particles > 0.4 micrometers%), the ratio of encapsulated rubber particles to unencapsulated rubber particles (ratio of encapsulated particles / unencapsulated particles), and the weight-average molecular weight (Mw) of the polymer matrix (MwSAN, expressed in g / moles) are linked by the following relationships: ; The preferred option is: ; Better to be: , The π series equals 3.14 and the NSG series is defined according to the following formula: .

[0060] According to a preferred embodiment of the present invention, the rubber-reinforced ethylene aromatic (co)polymer has the following properties: - The gloss value measured at 20° is greater than or equal to 50, preferably greater than or equal to 55, and even more preferably greater than or equal to 60; - The gloss sensitivity is less than or equal to 0.7, preferably less than or equal to 0.6, and even more preferably less than or equal to 0.5; - The impact resistance measured at 23°C is greater than or equal to 12 kJ / m², preferably greater than or equal to 14 kJ / m², and even more preferably greater than or equal to 16 kJ / m². - Puncture resistance is calculated as the product of fracture displacement (in millimeters) and fracture energy (in joules), which is greater than or equal to 400 joules per millimeter, preferably greater than or equal to 450 joules per millimeter, and more preferably greater than or equal to 500 joules per millimeter.

[0061] As described above, the present invention also relates to a method for preparing the rubber-reinforced ethylene aromatic (co)polymer reported above.

[0062] Therefore, a further objective of the present invention is a method for preparing rubber-reinforced ethylene aromatic (co)polymers, comprising the following steps: (a) Obtaining a functionalized low-cis polybutadiene rubber (LCBR) having a weight average molecular weight (Mw) in a low-boiling-point solvent between 40,000 g / mole and 110,000 g / mole, preferably between 50,000 g / mole and 100,000 g / mole, and even more preferably between 60,000 g / mole and 95,000 g / mole; (b) The low-boiling-point solvent is exchanged discontinuously with ethylene aromatic monomers; (c) Based on the obtained functionalized low-cis polybutadiene rubber (LCBR) grade, the functionalized low-cis polybutadiene rubber (LCBR) solution in ethylene aromatic monomers is stored in a buffer tank; (d) The solution of functionalized low-cis polybutadiene rubber (LCBR) stored in a buffer tank in an equal proportion of ethylene aromatic monomers is fed into a vessel; and another equal proportion of ethylene aromatic monomers (to achieve the desired rubber concentration in the reaction mixture), at least one solvent, at least one free radical polymerization initiator, at least one chain transfer agent, and other known additives are added; (e) The solution obtained in step (d) is continuously fed into a first plug flow reactor (PFR) (R1), and immediately before entering the first reactor (R1), a stream comprising at least one comonomer is fed; (f) The reaction mixture exiting the first reactor (R1) is continuously fed into a second plug flow reactor (PFR) (R2), which is also continuously fed into a solution of at least one chain transfer agent in a solvent; (g) Recover the rubber-reinforced ethylene aromatic (co)polymer from the polymerization plant; The functionalized low-cis polybutadiene rubber (LCBR) is characterized by the following facts: its weight-average molecular weight (Mw) (expressed in grams per mole), the chain transfer agent dosage (expressed in ppm, i.e., by weight, the amount of chain transfer agent fed into the first plug flow reactor (PFR) (R1) [step (e)]), and the average volume diameter (expressed in micrometers) of the functionalized low-cis polybutadiene rubber (LCBR) particles are linked by the following relationship: , The preferred option is: , Better to be: ,

[0063] It should be noted that in the aforementioned relationship: When the value is less than or equal to 0.5, the obtained rubber-reinforced ethylene aromatic (co)polymer has low aesthetic properties, particularly in terms of gloss and gloss sensitivity, and high mechanical properties, particularly in terms of impact resistance; conversely, when the above ratio has a value greater than 1.6, the obtained rubber-reinforced ethylene aromatic (co)polymer has high aesthetic properties, particularly in terms of gloss and gloss sensitivity, and low mechanical properties, particularly in terms of impact resistance.

[0064] The functionalized low-cis polybutadiene rubber (LCBR) can be obtained by performing step (a) of the aforementioned method as described in the art.

[0065] For this purpose, poly(1,3-diene), preferably 1,3-polybutadiene, is obtained by anionic radical polymerization of at least one 1,3-diene monomer, preferably 1,3-butadiene, in the presence of at least one aliphatic or cycloaliphatic low-boiling solvent or a mixture thereof and at least one initiator, preferably alkyllithium.

[0066] To ensure the properties of the functionalized low-cis polybutadiene rubber (LCBR) useful for the purposes of this invention, the aforementioned polymerization is carried out in a batch-type reactor. In this type of reactor, the initiator, typically primary or secondary butyllithium, is added to a reaction mixture comprising at least one aliphatic or cycloaliphatic low-boiling solvent (e.g., cyclohexane) or a mixture thereof and at least one 1,3-diene monomer, preferably 1,3-butadiene, in such amounts that at the end of the polymerization, the total amount of solids in the reaction mixture does not exceed 20% by weight relative to the total weight of the reaction mixture.

[0067] It is also known that the polymerization can be carried out in the presence of at least one Lewis base, in amounts varying depending on the desired content of 1,2-vinyl units in the polymer chain. The Lewis base is typically selected from ethers or tertiary amines, particularly tetrahydrofuran (THF), in an amount equal to 100 ppm in the solvent, which can significantly accelerate the polymerization reaction while maintaining the 1,2-vinyl unit content at a concentration below 12% (in moles). In the presence of higher amounts of THF, the microstructure gradually modifies the 1,2-vinyl unit content upwards to above 40% [e.g., THF equals 5000 ppm]: however, in the field of plastics modification, when using polymers such as polybutadiene, a high amount of 1,2-vinyl units is not necessary if it is harmless, and for this purpose, it is preferable that the 1,2-vinyl unit content is less than or equal to 25%.

[0068] It is also known that polymerization reactions in the absence of ethers or tertiary amines are fast enough to ensure that the monomer is fully polymerized within one hour and at a final temperature not exceeding 120°C, and that in any case where the initial temperature of the reaction mixture is adjusted to not be lower than 35°C-40°C, the reaction is not fast enough to start and is incompatible with normal production cycles.

[0069] In a batch-type reactor, the polymerization determines the formation of a polymer with a unimodal molecular weight distribution, wherein the degree of polymerization distribution index (PDI), that is, the ratio between the weight average molecular weight (Mw) and the number average molecular weight (Mn) (Mw / Mn), is very close to 1 and is usually between 1 and 1.2, and in any case not higher than 1.4.

[0070] The polymer obtained at the end of the polymerization is a linear polymer with reactive end groups composed of lithium-polydiene species (polybutadiene in the case of 1,3-butadiene monomers). While maintaining the linear macrostructure of the molecule, the termination of the lithium-butadiene end groups may be determined by the addition of a protogen (e.g., an alcohol or carboxylic acid) or a silane derivative (e.g., trimethylchlorosilane (TMCS)) with a halogen-to-silicon ratio of 1.

[0071] Therefore, in order to deactivate the terminal groups of the still active polymer chain, at least one terminator is usually added, preferably a compound having general formula (I) or (II): R 1-OH (I) Where R1 represents C1-C18 alkyl; R 2-OH (II) R2 represents C6-C18 alkyl.

[0072] At the end of the aforementioned polymerization, a solution of low cis polybutadiene rubber (LCBR) in a low-boiling-point aliphatic or cycloaliphatic solvent is obtained.

[0073] To functionalize the low-cis polybutadiene rubber (LCBR), a catalytic polymerization system is added to a solution consisting of at least one radical initiator (G) capable of drawing protons from the polymer chain of the aforementioned polybutadiene rubber and having a functional group F, and at least one stable radical initiator including nitro(NO·)(III) radicals. The system is operated at a nitro(NO·)(III) / (G)*F molar ratio of less than 4, preferably between 1 and 2, where F is equal to the number of functional groups per molecule of radical initiator (G), wherein the initiator generates two radicals by decomposition.

[0074] The reaction mixture thus obtained is heated to a temperature such that the free radical initiator (G) decomposes and maintained at that temperature for a period of time to ensure that at least 95% of the stable free radical initiator, including nitro radicals (NO·)(III), is bonded to the polymer chain of the low cis polybutadiene rubber (LCBR).

[0075] For the purposes of this invention, NSG is defined as the number of moles of stable free radical initiators, including nitrocellulose (NO·)(III), bonded to each low-cis polybutadiene rubber (LCBR), and is calculated according to the following formula: It must be less than or equal to 1, preferably between 0.05 and 1, more preferably between 0.2 and 0.8, and even more preferably between 0.3 and 0.7.

[0076] The free radical initiator (G) capable of drawing protons from the polybutadiene rubber polymer chain can be selected, for example, from: azo derivatives, such as, for example, 4,4'-bis-(di-isobutyronitrile), 4,4'-bis(4-cyanopentanoic acid), 2,2'-azobis(2-methanemidylpropane) dihydrochloric acid or mixtures thereof; peroxides; hydroperoxides; percarbonates; peresters; persulfates, such as, for example, persulfates (e.g., potassium persulfate, ammonium persulfate); or mixtures thereof. Preferably, the free radical initiator (G) is selected from peroxides, such as, for example, tributyl isopropyl monoperoxycarbonate, tributyl 2-ethylhexyl monoperoxycarbonate, dibutyl peroxide, etc. 1,1-Di(tert-butylperoxy)cyclohexane, 1,1-Di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, tert-butyl peracetate, peroxide Tributyl peroxide, tributyl peroxybenzoate, tributyl peroxy-2-ethylhexanoate, benzoyl peroxide, or mixtures thereof.

[0077] The stable free radical initiator comprising nitro(NO·)(III) can be selected from those having the general formula (IIIa): in: - R1, R2, R5, and R6 are the same or different from each other, representing linear or branched, substituted or unsubstituted C1-C20 alkyl or alkyl-(C1-C4)-aromatic groups; - R3 and R4 may be the same or different from each other, representing linear or branched, substituted or unsubstituted C1-C20 alkyl, alkyl-(C1-C4)-aromatic groups; or R3-CNC-R4 may be, for example, a part of a cyclic structure having 4 or 5 carbon atoms, selectively fused with an aromatic ring or with a saturated ring comprising 3 to 20 carbon atoms.

[0078] Further details relating to the stable radical initiator comprising nitro(NO·)(III) and its preparation method can be found, for example, in U.S. Patent 4,581,429.

[0079] For the purposes of this invention, preferably, the stable radical initiator comprising nitro(NO·)(III) is selected from 2,2,5,5-tetramethyl-1-pyrrolidoxoxy, 2,2,6,6-tetramethyl-1-piperidoxoxy (known as trade name TEMPO), 4-hydroxy-2,2,6,6-tetramethyl-1-piperidoxoxy (known as trade name 4OH-TEMPO), and 1,1,3,3-tetraethylisoindoline-2-oxy (known as trade name TEDIO). Further details relating to the stable radical initiator comprising nitro(NO·)(III) and its preparation method can be found, for example, in patent application WO 2004 / 078720.

[0080] At the end of step (a), step (b) can be performed as follows: the low-boiling solvent is exchanged with the ethylene aromatic monomer.

[0081] For this purpose, the low-boiling-point solvent is removed and replaced with an ethylene aromatic monomer (e.g., styrene) so that, relative to the total weight of the functionalized low-cis polybutadiene rubber (LCBR) in styrene, the final concentration of the functionalized low-cis polybutadiene rubber (LCBR) in styrene is maintained between 5 wt% and 45 wt%, preferably between 5 wt% and 40 wt%, and more preferably between 5 wt% and 35 wt%.

[0082] As reported above, in step (d), after storing the functionalized low-cis polybutadiene rubber (LCBR) solution in ethylene aromatic monomers obtained in step (b) in a buffer tank [step (c)], an additional equal amount of ethylene aromatic monomers (to achieve the desired concentration of the rubber in the reaction mixture), at least one solvent, at least one free radical polymerization initiator, at least one chain transfer agent, and other known additives are added.

[0083] The ethylene aromatic monomer can be selected from those reported above (e.g., styrene).

[0084] According to a preferred embodiment of the invention, in step (d), the solvent may be selected from aromatic solvents, such as, for example, ethylbenzene, toluene, xylene or mixtures thereof; or aliphatic solvents, such as, for example, hexane, cyclohexane or mixtures thereof; or mixtures thereof. Ethylbenzene is preferred.

[0085] According to a preferred embodiment of the invention, in step (d), the amount of the at least one free radical initiator that may be added is between 0% by weight and 0.7% by weight, more preferably between 0% by weight and 0.6% by weight, and even more preferably between 0.02% by weight and 0.5% by weight, relative to the total weight of the reaction mixture.

[0086] According to a preferred embodiment of the present invention, in step (d), the at least one free radical initiator may be selected from those having an activation temperature between 40°C and 170°C, preferably between 50°C and 150°C, and more preferably between 70°C and 140°C, such as, for example, 4,4'-bis-(di-isobutyronitrile), 4,4'-bis(4-cyanopentanoic acid), 2,2'-azobis(2-methanemidylpropane) dihydrochloric acid; peroxides; hydroperoxides; percarbonates; peresters; or mixtures thereof. Preferably, the at least one free radical initiator is selected from peroxides, such as, for example, tributyl-isopropyl monoperoxycarbonate, tributyl-2-ethylhexyl monoperoxycarbonate, dibutyl-isopropyl peroxide, etc. 1,1-Di(tert-butylperoxy)cyclohexane, 1,1-Di(tert-butylperoxy)-3,3,5-trimethylcyclohexane (di-tert-butylperoxycyclohexane), tert-butyl peracetate, peroxide Tributyl tert-butyl peroxybenzoate, tributyl peroxy-2-ethylhexanoate, or mixtures thereof.

[0087] According to a preferred embodiment of the invention, in step (d), the amount of the at least one chain transfer agent that may be added is between 0.01 wt% and 1 wt% relative to the total weight of the reaction mixture, preferably between 0.1 wt% and 0.8 wt%, and more preferably between 0.15 wt% and 0.6 wt%.

[0088] According to a preferred embodiment of the invention, in step (d), the at least one chain transfer agent may be selected, for example, from thiols, such as, for example, n-octylthiol, n-dodecylthiol (NDM), tertiary dodecylthiol, mercaptoethanol, or mixtures thereof. N-dodecylthiol (NDM) is preferred.

[0089] Other known additives that may be added in step (d) may be appropriately and differently selected, depending on the application of the obtained rubber-reinforced ethylene aromatic (co)polymer, such as antioxidants, UV stabilizers, plasticizers, mold release agents, athermans, flame retardants, blowing agents, antistatic agents, dyes, and stabilizers.

[0090] According to a preferred embodiment of the present invention, step (d) can be performed at a temperature between 30°C and 90°C, preferably between 40°C and 80°C.

[0091] According to a preferred embodiment of the invention, in step (e), the amount of the at least one comonomer that may be added is between 5% by weight and 35% by weight, more preferably between 10% by weight and 30% by weight, and even more preferably between 17% by weight and 27% by weight, relative to the total weight of the reaction mixture.

[0092] According to a preferred embodiment of the invention, step (e) can be performed at a temperature between 100°C and 130°C, preferably between 110°C and 125°C.

[0093] In step (f), the at least one chain transfer agent may be selected from those reported above.

[0094] According to a preferred embodiment of the invention, in step (f), the amount of the at least one chain transfer agent that may be added is between 0.5% by weight and 2.5% by weight, more preferably between 0.7% by weight and 2.2% by weight, and even more preferably between 0.9% by weight and 2% by weight, relative to the total weight of the reaction mixture.

[0095] According to a preferred embodiment of the invention, step (f) can be performed at a temperature between 120°C and 160°C, preferably between 130°C and 155°C.

[0096] The method of the present invention is advantageously carried out in a continuous bulk polymerization plant to obtain the desired rubber-reinforced ethylene aromatic (co)polymer: further details relating to the plant can be found, for example, in EP patent 0400479. Simple Explanation of the Diagram

[0097] Figure 1 shows the dimensions of the "three-stage" plate used to determine the gloss @20° of the obtained copolymer; Figure 2 shows the hemispherical head stamping press above the top view in the lower side view; and Figure 3 shows the test results of strength (Newtons) versus displacement (millimeters) for Examples 3, 8, and 9. Implementation

[0098] To better understand and implement the present invention, some illustrative and non-limiting embodiments are provided below. [Example]

[0099] The analytical methods and characteristics reported below were used. [a)] [Molecular weight distribution] [(MWD)] [Measurement]

[0100] Gel permeation chromatography (GPC), also known as size exclusion chromatography (SEC), is used to determine molecular weight distribution (MWD). This is done by allowing a (co)polymer solution to be analyzed in tetrahydrofuran (THF) to flow through a series of columns consisting of a solid phase composed of cross-linked polystyrene with different pore sizes.

[0101] The testing equipment used consists of the following components: - Waters 2695 syringe pump system; - Waters 2414 Differential Refractive Index Detector ("Detector RI"); - UV / Vis Waters 2489 detector.

[0102] The analysis was performed on four Phenogel columns with particle sizes of 5 μm and variable porosities of 10³, 10⁴, 10⁵, and 10⁶ Å. The (co)polymer sample to be analyzed was dissolved in tetrahydrofuran (THF) for at least 5 hours, achieving a concentration of 1 mg / mL in the case of both functionalized and unfunctionalized low-cis polybutadiene rubber (LCBR); and 2.5 mg / mL in the case of free styrene-acrylonitrile (SAN) copolymer; and subsequently filtered through a 0.45 μm polytetrafluoroethylene (PTFE) filter. The analysis was performed using tetrahydrofuran (THF) as the solvent at a rate of 1 mL / min.

[0103] The equipment was calibrated using 30 monodisperse polystyrene (PS) standards with a weight average molecular weight (Mw) between 7,000,000 and 1,000 Daltons.

[0104] To obtain the molecular weights of both functionalized and unfunctionalized low-cis polybutadiene rubber (LCBR) and free styrene-acrylonitrile (SAN) copolymer, refer to the general correction theory and use the Mark-Houwink equation, employing the constants shown in the table below: K (decliters / gram) a refer to polystyrene 1.6e -4 0.706 (i) LCBR 4.57e -4 0.693 (ii) SAN (24% AN) 1.46e -4 0.739 (iii) refer to: (i) Mori S. and Barth, HG in “Size Exclusion Chromatography” (1999), pg. 199-229, Springer Ed.; (ii) Evans JM, in “Polymer Engineering and Science” (1973), Vol. 13(6), pg. 401-408; (iii) Hamielec AE, MacGregor JF, Garcia Rubio, LH in “Advanced in Chemistry Series” (1963), Vol. 203, pg. 311-344.

[0105] The Waters Empower 2 software was used to acquire and process the chromatogram. The molecular weight was calculated using the chromatogram obtained from the detector RI.

[0106] Following the termination reaction, the rubber sample in cyclohexane was taken to determine the weight-average molecular weight (Mw) of the unfunctionalized low-cis polybutadiene rubber (LCBR). The sample was dried (by gently removing cyclohexane) and the dried residue was dissolved in tetrahydrofuran (THF) at room temperature (25°C) for at least 4 hours, using toluene as an internal standard.

[0107] Following the functionalization reaction, a rubber sample in cyclohexane was taken to determine the weight-average molecular weight (Mw) of the functionalized low-cis polybutadiene rubber (LCBR). The sample was dried (by gently removing cyclohexane) and the dried residue was dissolved in tetrahydrofuran (THF) at room temperature (25°C) for at least 4 hours, using toluene as an internal standard.

[0108] In the obtained reinforced ethylene aromatic copolymer acrylonitrile-butadiene-styrene (ABS), the weight average molecular weight (Mw) of the functionalized and unfunctionalized free low-cis polybutadiene rubber (LCBR) was determined by dissolving the copolymer sample in tetrahydrofuran (THF) at room temperature (25°C) for at least 4 hours, using toluene as an internal standard. The reported method f) is the separation of the functionalized and unfunctionalized free low-cis polybutadiene rubber (LCBR) in the acrylonitrile-butadiene-styrene (ABS) copolymer.

[0109] The weight-average molecular weight (Mw) of the free styrene-acrylonitrile (SAN) copolymer was determined by the following reported method e), in which the obtained sample was dissolved in tetrahydrofuran (THF) at room temperature (25°C) for at least 4 hours, and toluene was used as an internal standard. The reported method e) is the determination of the expansion index of the acrylonitrile-butadiene-styrene (ABS) copolymer. [b)] [Functionalized and unfunctionalized low-cis polybutadiene rubber] [(LCBR)] [Determination of the microstructure of both, and free low-cis polybutadiene rubbers, both functionalized and unfunctionalized] [(LCBR)] [Both are in acrylonitrile] [-] Butadiene [-] [Styrene] [(ABS)] [Determination of microstructure in copolymers]

[0110] The determination of the microstructure of functionalized and unfunctionalized low-cis polybutadiene rubber (LCBR), and the determination of the microstructure of functionalized and unfunctionalized free low-cis polybutadiene rubber (LCBR) in acrylonitrile-butadiene-styrene (ABS) copolymer were performed using a Bruker Avance 300 MHz spectrometer at a probe temperature of 300 K (26.85 °C).

[0111] The sample was prepared as follows: approximately 100 mg of the sample (obtained as described above) was weighed on an analytical balance and transferred into a borosilicate NMR tube (Wilmad®) with a diameter of 10 mm. Subsequently, approximately 3 mL of deuterated chloroform (CDCl3) (Sigma-Aldrich 99.96 atomic %D + TMS ~0.1% V / V) was added to obtain a viscous suspension, which was heated to 50 °C on a hot plate and maintained at that temperature for 2 hours until completely dissolved.

[0112] Then, a total of two NMR spectra were recorded: one for protons and one for carbon-13, and the collected parameters are shown in the table below: probe 10 mm BBO 300 MHz S1 with z-gradient 1H - 300 MHz 13C - 75 MHz method zg30 zgpg30 Number of scans (nanoseconds) 256 16k Data Point No. (TD) 64k 32k p1 (microsecond) 9.00 18.50 d1 (seconds) 7.0 3.0 Spectral window 16 ppm 239 ppm O1P 4.0 ppm 100.0 ppm solvent CDCl 399.96 atomic% D + TMS ~0.1% v / v

[0113] The obtained FID system was processed by Fourier transformation and zero-filling correction (SI: 128k). The 1H-NMR spectrum was processed without FID apodization (WDW: none), while the 13C-NMR spectrum was processed with exponential apodization (WDW: EM) and spectral broadening at 2.0 Hz.

[0114] Phase correction can be performed automatically or manually, and the baseline can be optimized via software algorithms. The chemical shift values ​​refer to the singlet resonance of tetramethylsilane (TMS) at 0.000 ppm (both in 1H-NMR and 13C-NMR spectra).

[0115] The determination of the complete microstructure of both functionalized and unfunctionalized free low-cis polybutadiene rubber (LCBR) samples in acrylonitrile-butadiene-styrene (ABS) copolymers requires processing the proton spectrum to quantify the 1,2-butadiene groups (1,2-vinyl units) and 1,4-butadiene (1,4-cis units and 1,4-trans units) in mole percentages; and processing the 13C-NMR spectrum, which is essentially used to determine the isomeric nature of the 1,4-cis and 1,4-trans units.

[0116] The 1H-NMR spectrum was processed according to ISO 21561-1:2015 (primarily applicable to styrene-butadiene polymers, but only suitable for the microstructure analysis of polybutadiene). Specifically, by integrating the resonances at 4.97 ppm (specifically indicated by letter A in the following reported formulas: integration range from 4.80 to 5.15 ppm) and 5.42 ppm (specifically indicated by letter B in the following reported formulas: integration range from 5.20 to 5.75 ppm), the total molar percentage distribution of 1,2-butadiene (1,2-vinyl unit) and 1,4-butadiene (1,4-cis and 1,4-trans units) groups can be calculated using equations (1) and (2). (1) (2).

[0117] The percentage determination of 1,4-cis and 1,4-trans units was performed by 13C-NMR spectroscopy, as reported by Sato H., Takebayashi K., and Tanaka Y. in Macromolecules (1987), Vol. 20, pg. 2418-2423. The relative integrals of the two signals (at 24.90 ppm and 27.42 ppm) immediately following the double bond in the cis configuration and the two signals (at 30.15 ppm and 32.71 ppm) immediately following the double bond in the trans configuration were calculated according to the following equations (3) and (4): (3) (4) The letter I indicates the integral value associated with the signal; the integration range is indicated by a subscript and expressed in ppm. [c)] [Low-cis polybutadiene rubbers in styrene, both functionalized and unfunctionalized] [(LCBR)] [Concentration Measurement]

[0118] The concentrations of both functionalized and unfunctionalized low cis-butadiene rubber (LCBR) in styrene were determined thermogravimetrically using a Sartorius MA50 thermobalance at the end of step (b) of the method objective of this invention (the exchange of the low-boiling-point nonpolar solvent with styrene).

[0119] For this purpose, 3 grams of both functionalized and unfunctionalized low-cis polybutadiene rubber (LCBR) in styrene were placed in a pre-calibrated container and heated to 200°C for 30 minutes to remove the styrene. Once cooled, the container and the dried residue were weighed, and the percentage of functionalized and unfunctionalized LCBR was determined by the ratio (dry / solution) between two weighings. [d)] [In acrylonitrile] [-] Butadiene [-] [Styrene] [(ABS)] [Low-cis polybutadiene rubbers of both functionalized and unfunctionalized copolymers] [(LCBR)] [Concentration Measurement]

[0120] The concentration of functionalized low cis-butadiene rubber (LCBR) in acrylonitrile-butadiene-styrene (ABS) copolymers was determined by iodide titration according to the Wys method reported by Wys JJA in "Berichte" (1898), Vol. 31, pg. 750-752. [e)] [Determination of the Inflation Index]

[0121] The degree of crosslinking of the rubber phase (i.e., rubber particles) in an acrylonitrile-butadiene-styrene (ABS) copolymer is measured by determining the expansion index of the copolymer.

[0122] For this purpose, the following method was followed: Two 50 mL steel tubes for centrifugation were prepared, each containing 0.5 g of acrylonitrile-butadiene-styrene (ABS) copolymer and 25 mL of acetone. These tubes were left to stand overnight at room temperature (25°C) to allow for complete dissolution. After mixing the solution with a rod, the volume was reduced to approximately 30 mL using acetone and centrifuged for 20 minutes at 20,000 rpm (45,000 g) using a Sorvall Evolution RC laboratory centrifuge with an SA300 motor. At the end of the centrifugation, the supernatant was decanted and stored for analysis of the weight-average molecular weight (Mw) of the free styrene-acrylonitrile copolymer, as reported below.

[0123] Once the acetone is removed, the rubber phase that had filled the bottom of the tube was diluted by adding 10 mL of tetrahydrofuran (THF). The volume was brought to about 30 mL using tetrahydrofuran (THF), and the whole volume was centrifuged at 20,000 rpm (45,000 g) for 20 minutes and the resulting supernatant was decanted.

[0124] Simultaneously, a crucible equipped with a dry, porous Gooch separator is weighed (first weight = P1), wherein the crucible is immersed in a vessel containing tetrahydrofuran (THF) for at least one hour: the THF level is at the height of the porous separator of the crucible, and the vessel is kept in a closed container. Subsequently, the crucible is removed, the solvent on the glass wall is dried without contacting the moist porous separator, and the entire crucible is quickly weighed (second weight = P2).

[0125] Using a scraper, recover the solid residue from the two test tubes that has deposited on the porous partition of the crucible without contacting the wall, and then disperse it in a manner that completely covers the porous partition: leave everything in the vessel to swell at room temperature (25°C) for 5 hours. Remove the crucible again, dry the solvent on the glass wall without contacting the moistened porous partition or the solid deposited thereon, and weigh the entire contents again quickly (third weight = P3).

[0126] At this point, ethanol is added dropwise to the solid residue present in the crucible until the crucible is completely filled and the mixture is filtered. The solid residue remaining in the crucible is dried in an oven under vacuum at 40°C for 12 hours. Finally, the crucible and the dried gel are weighed (4th weight = P4).

[0127] The expansion index value is calculated according to the following formula (5): .

[0128] The supernatant obtained after the first centrifugation was processed as follows: after complete removal of acetone, the obtained solid residue was dissolved in a minimal amount of tetrahydrofuran (THF), reprecipitated in ethanol, filtered, dried in an oven at 40°C under vacuum for 12 hours, and subsequently subjected to gel permeation chromatography (GPC) as described above. [a)] [Molecular weight distribution] [(MWD)] The procedure described in [the determination] is the same. [f)] [in the acrylonitrile] [-] Butadiene [-] [Styrene] [(ABS)] [Free low-cis polybutadiene rubber of both functionalized and unfunctionalized copolymers] [(LCBR)] [Separation]

[0129] The weight-average molecular weight (Mw) and microstructure of the functionalized and unfunctionalized free (uncrosslinked) low-cis polybutadiene rubber (LCBR) in the acrylonitrile-butadiene-styrene (ABS) copolymer were determined by modifying the method reported by Turner RR, Carlson DW, and Altenau AG in the "Journal of Elastomers and Plastics" (1974), Vol. 6, pg. 94-102.

[0130] For this purpose, eight 50 mL steel tubes for centrifugation were prepared, each containing 0.5 g of acrylonitrile-butadiene-styrene (ABS) copolymer and 25 mL of acetone. The tubes were left to stand overnight at room temperature (25°C) to allow for complete dissolution. After mixing the solution with a rod, the volume was brought to approximately 30 mL with acetone and centrifuged at 20,000 rpm (45,000 g) for 30 minutes using a Sorvall Evolution RC laboratory centrifuge with an SA300 motor. At the end of centrifugation, the supernatant was decanted. Once the acetone was removed, the rubber phase that had filled the bottom of the tube was diluted by adding 10 mL of acetone, the volume was brought to approximately 30 mL with acetone, and the tube was centrifuged at 20,000 rpm (45,000 g) for 30 minutes. The resulting supernatant was then decanted. This process was repeated twice. The solid residue (rubber phase) deposited at the bottom of the tube was recovered and placed in the sleeve of a Kumagawa extractor. Add 200 mL of cyclohexane to the extractor and allow the mixture to reflux for 24 hours. Dry the cyclohexane solution by evaporation and subject the resulting solid residue to gel permeation chromatography (GPC) as described above. [a)] [Molecular weight distribution] [(MWD)] The weight-average molecular weight (Mw) was determined using the procedures described in [Determination of Molecular Weight]; and NMR analysis was performed as described above. [b)] [Low cis polybutadiene rubbers, both functionalized and unfunctionalized] [(LCBR)] [Determination of the microstructure of free low-cis polybutadiene rubber, both functionalized and unfunctionalized] [(LCBR)] [in the acrylonitrile] [-] Butadiene [-] [Styrene] [(ABS)] The procedure is as described in the method reported in [Determination of Microstructure in Copolymers]. [g)] [Transmission Electron Microscope] [(TEM)] [and image analysis]

[0131] The particle size and rubber phase volume of the low cis polybutadiene rubber (LCBR) were determined by transmission electron microscopy (TEM).

[0132] For this purpose, a sample (particle) of styrene-butadiene-acrylonitrile (ABS) copolymer was placed in a clamp and properly trimmed to prepare a surface suitable for subsequent ultrathin sectioning. The sample was then immersed in a 4% osmium tetroxide (OsO₄) solution (Sigma-Aldrich) for approximately 48 hours at room temperature (25°C) (“staining”). Following this treatment, the sample possessed sufficient rigidity for ultrathin sectioning at room temperature (25°C), yielding sections with a thickness of approximately 120 nanometers (determined by the interference color when the section was exposed upon cutting). These sections were collected on a copper grid and observed using a transmission electron microscope (TEM) PHILIPS CM120 at 80 kV.

[0133] Then, a series of images of the sample are digitized at equal magnification to obtain a statistically significant count of particles (typically around 1000). These images are analyzed using AnalySIS image analysis software: image analysis allows us to extract numerical parameters from these images, such as area, perimeter, diameter, extinction, optical density, transmittance, topological parameters, and similar values. Once the image has been reconstructed into numerical form using a suitable acquisition and processing system, it becomes possible to obtain information from the image using mathematical algorithms. The image analysis used for the numerical determination of the dispersed rubber phase is performed as described in U.S. Patent 7,115,684 (column 22 to column 65 of U.S. Patent 7,115,684). In particular, the "dispersion factor I" values ​​reported in Tables 2a-2d are determined as described in column 54-60 of the aforementioned U.S. Patent 7,115,684, while the average volume diameter of the rubber particles is determined as described in column 35-30 of the aforementioned U.S. Patent 7,115,684.

[0134] All image and appearance raw data have been stored and are available for further processing for any stereoscopic purpose, with the goal of reconstructing the true diameter and volume distribution of these particles in the styrene-butadiene-acrylonitrile (ABS) copolymer sample. [h)] [Measurement in the presence of encapsulated rubber particles] [ / ] [Ratio between unencapsulated rubber particles]

[0135] The ratio between unencapsulated rubber particles (hereinafter referred to as spheres) and encapsulated rubber particles (hereinafter referred to as caps and "salami") is determined by performing the method described above. [g)] [Transmission Electron Microscope] [(TEM)] [And image analysis] to pre-determine the total count of these particles.

[0136] In particular, the following definitions have been made: - Sphere: The matrix does not contain any encapsulated rubber particles; - Crown: A rubber particle whose single matrix encapsulation area occupies at least 85% of its total surface area; - "Italian sausage": rubber particles containing two or more matrices; in this type of particle, the area of ​​the matrices does not occupy more than 85% of the total surface area of ​​the particle itself.

[0137] Encapsulation is defined as a light-colored surface within the rubber particle with an area of ​​at least 0.01 square micrometers.

[0138] In order to define the relationship between unenclosed rubber particles (spheres) and enclosed rubber particles [crowns and "Italian sausages"], different colors are used to highlight particle types with the morphology defined above in the images obtained as described above.

[0139] This analysis is also performed on a statistically significant number of particles (typically around 1000). During this calculation phase, the software can process and analyze data using a single color to calculate the percentage and relative ratio of each identified particle type. The percentage of different particle types is expressed relative to the total number of particles analyzed, and also represents the number of particles of a particular type relative to that total number of particles.

[0140] The ratio of contained particles to uncontained particles is defined as follows: Including enclosed particles / Unenclosed particles = .

[0141] In this case, images and data are also stored for any future processing. [i] [)] Melt Flow Index [(MFI)] [Measurement]

[0142] The melt flow index (MFI) is measured at 220°C with a weight of 10 kg, according to ISO 1133-1:2011 standard. [l)] [Aish] [(Izod)] [Measurement] [(] [Impact Resistance] [)]

[0143] The notched Irrod value (on injection-molded samples according to ISO 294:1-2017) is determined according to ISO 180 / 1A-2020 and is expressed in kilojoules per square meter. [m)] Tensile strength

[0144] The tensile strength property (on injection-molded specimens according to ISO 294:1-2017) was determined according to ISO 527-1:2019, and the values ​​are shown below: - Elastic modulus: one million Pascals; - Yield stress: one million Pascals; - Fracture stress: one million Pascals; - Yield elongation: %; - Elongation at break: %. [n)] [Gloss Measurement]

[0145] The gloss of the styrene-butadiene-acrylonitrile (ABS) copolymer was measured using a BYG Gardner Model 4563 gloss meter at a reading angle of 20°, according to standard ASTM D523-14:2018.

[0146] The measurement was performed according to ISO 294:1-2017 on "third-order" samples obtained by injection molding using a Negri & Bossi NB60 injection molding machine (see Figure 1, which shows the dimensions of the "third-order" plate used to determine the gloss @20° of the obtained copolymer). Specifically, the gloss measurement was performed at the height of the injection point in the central portion of the plate (second order, with dimensions of 93 x 75 x 3 mm). The measured gloss value was the average reading of at least 10 samples operated under the following conditions: - Melting temperature: 240℃; - Molding temperature: 25℃. [o)] [Gloss Sensitivity Measurement]

[0147] The gloss sensitivity was measured according to ASTM D523-14:2018 standard, using a GARD PLUS model 4725 gloss meter at a reading angle of 20°.

[0148] The measurement was performed on a flat sample with dimensions of 60x60x3 mm, obtained by injection molding using an ENGEL ES 150 / 50 injection molding machine in accordance with ISO 294-3:2002 standard.

[0149] At the center of the printed plate, gloss values ​​(average of at least 10 samples) were measured at different locations under the following different operating conditions: - Melting temperature: 240℃; - Ejection velocity: 100 mm / s or 300 mm / s; - Molding temperature: 30℃ or 60℃.

[0150] Once the injection speed is defined (e.g., 100 mm / s), 10 plates are molded at different molding temperatures (30°C or 60°C). The same operation is repeated by varying the injection speed. In this way, we define the 2x2 matrix value according to the following equation (11): (11).

[0151] The gloss sensitivity value is defined according to the following formula (12): (12). [p)] [Biaxial Flexural Measurement] [(] [Puncture Resistance] [)]

[0152] The biaxial flexural strength (puncture resistance) measurement was performed using an INSTRON Model 4400 R universal testing machine (using Bluehill 2.35 control software) equipped with an upward-moving crosshead conforming to ISO 7500-1:2018 standard. This universal testing machine maintained a constant crosshead speed of 50 mm / min with a tolerance of ±10% during the test. The machine is equipped with a stamping press with a hemispherical head having a radius of curvature R = 10 mm and a circular support with an outer diameter of 148 mm to support the sample. On the upper surface of this support, there is a concentric cover with a diameter of 85 mm; this cover is useful for holding the sample in the correct position. The circular support also has a concentric hole with a diameter of 40 mm to allow the sample to deform during the test. Insert the press into the movable crosshead and fix it in place, and fasten the circular support to the base of the universal testing machine so that the vertical axis of the press overlaps with the vertical axis of the circular support.

[0153] The geometry used in the test is illustrated in Figure 2, which shows a hemispherical head press (dimensions in millimeters) above the top view in the lower side view ("Provino" = "sample"). The biaxial flexure geometry depicted in Figure 2 is determined by the extremely complex stress state in the sample during the test: in fact, by dividing the stress into radial, peripheral, and vertical components (in a coordinate system, the origin is at the center of the sample and the vertical axis is parallel to the thickness of the sample), there is a biaxial traction force at the center of the face opposite the loaded press, and a biaxial compression at the center of the face in contact with the press. Moving toward the circular support, the peripheral stress increases and the radial stress decreases, thus producing a shear stress state. The complexity of the stress state produced in the sample makes it convenient to use isotropic samples, or samples with molecular orientation states (due to, for example, injection molding), that are as geometrically simple and controllable as possible and may be very independent of the thermal and rheological characteristics of the material. For this purpose, injection-molded test specimens consisting of square plates with dimensions of 60x60x2 (mm) were used, formed according to ISO 294-3:2002. The injection molding conditions were selected according to ISO 19062-2:2019: the specimens were placed in the outer casing of the lower support so that the press could penetrate its central portion; the upper press, fastened to the crosshead, moved at a speed of 50 mm / min. The universal testing machine software acquired and plotted the force (Newtons) versus displacement (mm) data, and obtained the following output parameters from each test run: - Fracture displacement (mm): The value of this crosshead displacement corresponds to the point at which the sample begins to fracture (fracture is detected when the force measured between two successive sampling points is equal to or greater than 20%). - Fracture strength (Newtons): The force value at the point where the sample begins to fracture (see above); - Fracture energy (joules): The area value opposite to the overall curve from the highest point to the start of the fracture, which represents the energy of the sample deformed to the highest point at the start of the fracture.

[0154] As reported above, puncture resistance is calculated by multiplying the fracture displacement (in millimeters) by the fracture energy (in joules), with the unit of measurement being joules per millimeter.

[0155] As described above, the present invention also relates to a method for preparing rubber-reinforced ethylene aromatic (co)polymers.

[0156] As an example, Figure 3 shows some test results, in which the solid line indicates Example 3 (for comparison), the dashed line indicates Example 8 (for comparison), and the dimpled-dotted line indicates Example 9 (invention).

[0157] List A below shows a list of reagents used in the following examples, their characteristics, and suppliers. Table A reagents Product Name (Abbreviation) supplier feature butadiene (BDE) Versalis Purity > 99.5% Cyclohexane - Cepsa Purity > 99.5% n-Butyllithium* (nBL) Albemarle Active lithium = 15% heptanoic acid - Sigma-Aldrich Purity > 97% ethanol - Sigma-Aldrich Purity > 96% Dibenzyl peroxide Perkadox L-W75 (BPO) Akzo Nobel 75% in water 4-Hydroxy-2,2,6,6-Tetramethyl Piperidine 1-oxy (4OH-TEMPO) Sigma-Aldrich Purity > 97% styrene (SM) Versalis Purity > 99.7% Ethylbenzene (EB) Versalis Purity > 99.0% Acrylonitrile (ACN) Ineos Purity > 99.4% Europrene® SOL B183 (SBR) Versalis Bonded polystyrene: 8-12% Viscosity (@5% in styrene): 32 cPs 1,1-Bis(tert-butylperoxy) Cyclohexane Trigonox 22-E50 (Tx22E50) Akzo Nobel 50% in mineral oil n-Dodecylthiol (NDM) Arkema Purity > 97.8% Octadecyl 3-(3,5-di-)propionate (tert-butyl-4-hydroxyphenyl) ester Irganox® 1076 BASF Purity > 98.0% *The n-butyllithium is diluted from 15% to 2% with anhydrous cyclohexane (Cepsa) before use. [Example] [1(] [For comparison] [)]

[0158] The following were loaded into a 50-liter vessel equipped with a stirrer: 21.4 kg styrene, 3.7 kg ethylbenzene, 4.9 kg SBR Europrene® SOL B183 rubber, 11.5 g 1,1-bis(tert-butylperoxy)cyclohexane [Trigonox 22-E50 (Tx22E50)] (free radical initiator), and 55.6 g octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Irganox® 1076) (antioxidant). The resulting solution was continuously fed at a flow rate of 3.8 kg / h into a first 10-liter plug flow reactor (PFR) (R1) equipped with a stirrer and temperature control system. Acrylonitrile was immediately added to the solution at a flow rate of 0.7 kg / h before entering the first plug flow reactor (PFR) (R1). The thermal profile of the reactor was maintained at 113°C to 122°C with a constant stirring speed of 80 rpm. Prepolymerization, grafting, and phase inversion were carried out in the first plug flow reactor (PFR)(R1). A solution of n-dodecyl mercaptan (NDM) (chain transfer agent) in ethylbenzene (EB) was continuously added (0.15 kg / h) to the mixture leaving the first plug flow reactor (PFR)(R1) [60.0 g NDM in 0.940 kg (EB), corresponding to a NDM concentration of 6.0% in ethylbenzene], and fed into a second plug flow reactor (PFR)(R2), which was also equipped with a stirrer and temperature control system, and whose thermal profile was maintained at 139°C to 150°C with a constant stirring speed of 10 rpm.

[0159] The obtained mixture was fed into a devolatilizer operating at 255°C under vacuum to remove unreacted styrene and solvent from the copolymer, thereby obtaining the final copolymer. The reaction conditions used in this method are shown in Table 1a. The characteristics of the obtained product are shown in Table 2a. [Example] [2(] [For comparison] [)]

[0160] In a nitrogen stream, the following feed is sequentially introduced into a 300-liter reactor, which is kept anhydrous, equipped with a stirrer, and a heated shroud in which through-heated oil at 50°C is circulated: 124.4 kg of anhydrous cyclohexane, 22.0 kg of anhydrous butadiene without inhibitors and alkynes, and, when the reaction mixture has reached a temperature of 40°C, 1208.0 g of a 2% by weight n-butyllithium (nBL) solution in cyclohexane. After the conversion is complete, the reaction mixture is fed at 115°C into a second 300-liter reactor equipped with a stirrer and a heated shroud in which through-heated oil at 25°C is circulated. At this point, an equal amount of 22.0 g of ethanol is also introduced to complete the chain termination.

[0161] A sample of low-cis polybutadiene rubber (LCBR) was subjected to gel permeation chromatography (GPC) as reported above for molecular weight distribution determination. The obtained weight-average molecular weight (Mw) was 60206 g / mole and the degree of polymerization distribution index (PDI) (Mw / Mn) was 1.02.

[0162] The reaction mixture comprising the low-cis polybutadiene rubber (LCBR) obtained as described above and cyclohexane was transferred to an 800-liter batch pressure cooker equipped with a temperature controller, stirring system, vacuum control system, and condensate collection system. The pressure cooker was maintained at a constant temperature of 25°C and placed under a vacuum of 70 mbar. Once liquid was observed in the condensate collection system, 248.8 kg of styrene was slowly added while the temperature of the pressure cooker was increased to a maximum of 66°C. The solvent exchange operation was completed once 313.1 kg of condensate was collected. The concentration of cyclohexane in the styrene solution was less than 500 ppm. The final solution was stored in a buffer tank, and at the end of the solvent exchange operation, the concentration of the low-cis polybutadiene rubber (LCBR) in the styrene was equal to 26.8%.

[0163] 16.6 kg of low-cis polybutadiene rubber (LCBR) in an equivalence of 26.8% in styrene was transferred into a 50-liter vessel equipped with a stirrer, followed by feeding: 9.7 kg of styrene, 3.7 kg of ethylbenzene, 11.5 g of di-1,1-bis(tert-butylperoxy)cyclohexane [Trigonox 22-E50 (Tx22E50)] (free radical initiator), and 55.6 g of octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Irganox® 1076) (antioxidant). The resulting solution was continuously fed at a flow rate of 3.8 kg / h into a first 10-liter plug flow reactor (PFR) (R1) equipped with a stirrer and temperature control system. Acrylonitrile was immediately added to the solution at a flow rate of 0.7 kg / h before entering the first plug flow reactor (PFR) (R1). The thermal profile of the reactor increased from 113°C to 122°C while the stirring speed remained constant at 80 rpm. Prepolymerization, grafting, and phase inversion were carried out in the first plug flow reactor (PFR)(R1). A solution of n-dodecyl mercaptan (NDM) chain transfer agent in ethylbenzene (EB) [60.0 g NDM in 0.940 kg (EB), corresponding to a concentration of 6.0% NDM in ethylbenzene] was continuously added (0.15 kg / h) to the mixture leaving the plug flow reactor (PFR)(R1) and fed into a second plug flow reactor (PFR)(R2), also equipped with a stirrer and temperature control system, where the thermal profile increased from 139°C to 150°C while the stirring speed remained constant at 10 rpm.

[0164] The obtained mixture was fed into a devolatilizer operating at 255°C under vacuum to remove unreacted styrene and solvent from the copolymer, thereby obtaining the final copolymer. The reaction conditions used in this method are shown in Table 1a. The characteristics of the obtained product are shown in Table 2a. [Example] [3(] [For comparison] [)]

[0165] In a nitrogen stream, the following feed is sequentially introduced into a 300-liter reactor, which is kept anhydrous, equipped with a stirrer, and a heated shroud in which through-heated oil at 50°C is circulated: 124.4 kg of anhydrous cyclohexane, 22.0 kg of anhydrous butadiene without inhibitors and alkynes, and when the reaction mixture has reached a temperature of 40°C, 967.0 g of a 2% by weight n-butyllithium (nBL) solution in cyclohexane is introduced. After the conversion is complete, the reaction mixture is fed at 113°C into a second 300-liter reactor equipped with a stirrer and a heated shroud in which through-heated oil at 25°C is circulated, and at this time, an equal amount of 51.0 g of heptanoic acid is introduced to complete the chain termination.

[0166] A low-cis polybutadiene rubber (LCBR) sample was subjected to gel permeation chromatography (GPC) as reported above to determine its molecular weight distribution. The obtained weight-average molecular weight (Mw) was 77,561 g / mole and the degree of polymerization distribution index (PDI) (Mw / Mn) was 1.04.

[0167] The reaction mixture containing the low-cis-butadiene rubber (LCBR) obtained as described above and cyclohexane was transferred to an 800-liter batch pressure cooker equipped with a temperature controller, stirring system, vacuum control system, and condensate collection system. The pressure cooker was maintained at a constant temperature of 25°C and placed under a vacuum of 70 mbar. Once liquid was observed in the condensate collection system, 248.8 kg of styrene was slowly added while the temperature of the pressure cooker was increased to a maximum of 66°C. The solvent exchange operation was completed once 301.2 kg of condensate had been collected. The concentration of cyclohexane in the styrene solution was less than 500 ppm. The final solution was stored in a buffer tank, and at the end of the solvent exchange operation, the concentration of the low-cis-butadiene rubber (LCBR) in the styrene was equal to 23.4%.

[0168] A solution of 19.0 kg of low-cis polybutadiene rubber (LCBR) in styrene at a concentration of 23.4% was transferred to a 50-liter vessel equipped with a stirrer. The following were then fed into the solution: 7.3 kg of styrene, 3.7 kg of ethylbenzene, 11.5 g of di-1,1-bis(tert-butylperoxy)cyclohexane [Trigonox 22-E50 (Tx22E50)] (free radical initiator), and 55.6 g of octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Irganox® 1076) (antioxidant). The resulting solution was continuously fed at a flow rate of 3.8 kg / h into a first 10-liter plug flow reactor (PFR) (R1) equipped with a stirrer and temperature control system. Acrylonitrile was immediately added to the solution at a flow rate of 0.7 kg / h before entering the first plug flow reactor (PFR) (R1). The thermal profile of the reactor increased from 113°C to 122°C while the stirring speed remained constant at 80 rpm. Prepolymerization, grafting, and phase inversion were carried out in the first plug flow reactor (PFR)(R1). A solution of n-dodecyl mercaptan (NDM) chain transfer agent in ethylbenzene (EB) [45.0 g NDM in 0.955 kg (EB), corresponding to a NDM concentration of 4.5% in ethylbenzene] was continuously added (0.15 kg / h) to the mixture leaving the plug flow reactor (PFR)(R1) and fed into a second plug flow reactor (PFR)(R2), also equipped with a stirrer and temperature control system, where the thermal profile increased from 139°C to 150°C while the stirring speed remained constant at 10 rpm.

[0169] The obtained mixture was fed into a devolatilizer operating at 255°C under vacuum to remove unreacted styrene and solvent from the copolymer, thereby obtaining the final copolymer. The reaction conditions used in this method are shown in Table 1a. The characteristics of the obtained product are shown in Table 2a. [Example] [4(] [For comparison] [)]

[0170] In a nitrogen stream, the following feed is sequentially introduced into a 300-liter reactor, which is kept anhydrous, equipped with a stirrer, and a heated shroud in which through-heated oil at 50°C is circulated: 124.4 kg of anhydrous cyclohexane, 22.0 kg of anhydrous butadiene without inhibitors and alkynes, and, when the reaction mixture has reached a temperature of 40°C, 806.0 g of a 2% by weight n-butyllithium (nBL) solution in cyclohexane. After the conversion is complete, the reaction mixture is fed at 111°C into a second 300-liter reactor equipped with a stirrer and a heated shroud in which through-heated oil at 25°C is circulated, and at the same time, an equal amount of 42.0 g of heptanoic acid is introduced to complete the chain termination.

[0171] A low-cis polybutadiene rubber (LCBR) sample was subjected to gel permeation chromatography (GPC) as reported above to determine its molecular weight distribution. The obtained weight-average molecular weight (Mw) was 91,586 g / mole and the degree of polymerization distribution index (PDI) (Mw / Mn) was 1.06.

[0172] The reaction mixture containing low-cis polybutadiene rubber (LCBR) and cyclohexane, obtained as described above, was transferred to an 800-liter batch pressure cooker equipped with a temperature controller, stirring system, vacuum control system, and condensate collection system. The pressure cooker was maintained at a constant temperature of 25°C and placed under a vacuum of 70 mbar. Once liquid was observed in the condensate collection system, 248.8 kg of styrene was slowly added while the temperature of the pressure cooker was increased to a maximum of 66°C. The solvent exchange operation was completed once 289.4 kg of condensate had been collected. The concentration of cyclohexane in the styrene solution was less than 500 ppm. The final solution was stored in a buffer tank, and at the end of the solvent exchange operation, the concentration of low-cis polybutadiene rubber (LCBR) in the styrene was equal to 20.8%.

[0173] 21.4 kg of low-cis polybutadiene rubber (LCBR) in an equivalence of 20.8% styrene was transferred to a 50-liter vessel equipped with a stirrer, and then the following were fed into it: 4.9 kg styrene, 3.7 kg ethylbenzene, 11.5 g di-1,1-bis(tert-butylperoxy)cyclohexane [Trigonox 22-E50 (Tx22E50)] (free radical initiator), and 55.6 g octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Irganox® 1076) (antioxidant). The resulting solution was continuously fed at a flow rate of 3.8 kg / h into a first 10-liter plug flow reactor (PFR) (R1) equipped with a stirrer and temperature control system. Acrylonitrile was immediately added to the solution at a flow rate of 0.7 kg / h before entering the first plug flow reactor (PFR) (R1). The thermal profile of the reactor was maintained at 113°C to 122°C with a constant stirring speed of 80 rpm. Prepolymerization, grafting, and phase inversion were carried out in the first plug flow reactor (PFR)(R1). A solution of n-dodecyl mercaptan (NDM) chain transfer agent in ethylbenzene (EB) [45.0 g NDM in 0.955 kg (EB), corresponding to a NDM concentration of 4.5% in ethylbenzene] was continuously added (0.15 kg / h) to the mixture leaving the plug flow reactor (PFR)(R1) and fed into a second plug flow reactor (PFR)(R2), also equipped with a stirrer and temperature control system, where the thermal profile was maintained at 139°C to 150°C with a constant stirring speed of 10 rpm.

[0174] The obtained mixture was fed into a devolatilizer operating at 255°C under vacuum to remove unreacted styrene and solvent from the copolymer, thereby obtaining the final copolymer. The reaction conditions used in this method are shown in Table 1a. The characteristics of the obtained product are shown in Table 2a. [Example] [5(] [For comparison] [)]

[0175] In a nitrogen stream, the following feed is sequentially introduced into a 300-liter reactor, which is kept anhydrous, equipped with a stirrer, and a heated shroud in which through-heated oil at 50°C is circulated: 124.4 kg of anhydrous cyclohexane, 22.0 kg of anhydrous butadiene without inhibitors and alkynes, and, when the reaction mixture has reached a temperature of 40°C, 1208.0 g of a 2% by weight n-butyllithium (nBL) solution in cyclohexane. After the conversion is complete, the reaction mixture is fed at 115°C into a second 300-liter reactor equipped with a stirrer and a heated shroud in which through-heated oil at 25°C is circulated, and at the same time, an equal amount of 64.0 g of heptanoic acid is introduced to complete the chain termination.

[0176] A low-cis polybutadiene rubber (LCBR) sample was subjected to gel permeation chromatography (GPC) as reported above to determine its molecular weight distribution. The weight-average molecular weight (Mw) was 59,731 g / mole and the degree of polymerization distribution index (PDI) (Mw / Mn) was 1.02.

[0177] In the reaction mixture containing low-cis polybutadiene rubber (LCBR) and cyclohexane obtained as described above, 38.1 g of dibenzyl peroxide [Perkadox 1-W75(BPO)] and 31.5 g of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy (4OH-TEMPO) were added. The mixture thus obtained was kept at a constant temperature of 105°C and stirred at this temperature for 3 hours until the low-cis polybutadiene rubber (LCBR) chain was functionalized with 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy (4OH-TEMPO).

[0178] The molecular weight distribution of functionalized low-cis polybutadiene rubber (LCBR) samples was determined by gel permeation chromatography (GPC) as described above, yielding a weight-average molecular weight (Mw) of 59,254 g / mole and a degree of polymerization distribution index (PDI) (Mw / Mn) of 1.02.

[0179] The functionalized low-cis polybutadiene rubber (LCBR) solution obtained as described above was transferred to an 800-liter batch pressure cooker equipped with a temperature controller, stirring system, vacuum control system, and condensate collection system. The pressure cooker was maintained at a constant temperature of 25°C and placed under a vacuum of 70 mbar. Once liquid was observed in the condensate collection system, 248.8 kg of styrene was slowly added while the temperature of the pressure cooker was increased to a maximum of 66°C. The solvent exchange operation was completed once 315.2 kg of condensate had been collected. The concentration of cyclohexane in the styrene solution was less than 500 ppm. The final solution was stored in a buffer tank, and at the end of the solvent exchange operation, the concentration of the functionalized low-cis polybutadiene rubber (LCBR) in the styrene was equal to 27.5%.

[0180] A 16.2 kg equivalent of a functionalized low-cis polybutadiene rubber (LCBR) solution, comprising 27.5% styrene, was transferred to a 50-liter vessel equipped with a stirrer. The following were then fed into the vessel: 10.1 kg styrene, 3.7 kg ethylbenzene, 11.5 g di-1,1-bis(tert-butylperoxy)cyclohexane [Trigonox 22-E50 (Tx22E50)] (free radical initiator), 55.6 g octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Irganox® 1076) (antioxidant), and 9.3 g n-dodecyl mercaptan (NDM) chain transfer agent. The resulting solution was continuously fed at a flow rate of 3.8 kg / h into a first 10-liter plug flow reactor (PFR) (R1) equipped with a stirrer and temperature control system. Acrylonitrile was immediately added to the solution at a flow rate of 0.7 kg / h before entering the first plug flow reactor (PFR)(R1). The thermal profile of this reactor increased from 113°C to 122°C while the stirring speed remained constant at 80 rpm. In the first plug flow reactor (PFR)(R1), the prepolymerization, grafting, and phase inversion were carried out. The mixture leaving the plug flow reactor (PFR)(R1) was continuously added (0.15 kg / h) of a n-dodecyl mercaptan (NDM) chain transfer agent solution in ethylbenzene (EB) [54.0 g NDM in 0.946 kg (EB), corresponding to a NDM concentration of 5.4% in ethylbenzene], and fed into a second plug flow reactor (PFR)(R2), which was also equipped with a stirrer and a temperature control system, wherein the thermal profile of this reactor increased from 139°C to 150°C while the stirring speed remained constant at 10 rpm.

[0181] The obtained mixture was fed into a devolatilizer operating at 255°C under vacuum to remove unreacted styrene and solvent from the copolymer, thereby obtaining the final copolymer. The reaction conditions used in this method are reported in Table 1b. The characteristics of the obtained product are shown in Table 2b. [Example] [6(] [invention] [)]

[0182] In a nitrogen stream, the following feed is sequentially introduced into a 300-liter reactor, which is kept anhydrous, equipped with a stirrer, and a heated shroud in which through-heated oil at 50°C is circulated: 124.4 kg of anhydrous cyclohexane, 22.0 kg of anhydrous butadiene without inhibitors and alkynes, and, when the reaction mixture has reached a temperature of 40°C, 1208.0 g of a 2% by weight n-butyllithium (nBL) solution in cyclohexane. After the conversion is complete, the reaction mixture is fed at 115°C into a second 300-liter reactor equipped with a stirrer and a heated shroud in which through-heated oil at 25°C is circulated, and at the same time, an equal amount of 22.0 g of ethanol is introduced to complete the chain termination.

[0183] A low-cis polybutadiene rubber (LCBR) sample was subjected to gel permeation chromatography (GPC) as described above to determine its molecular weight distribution, yielding a weight-average molecular weight (Mw) of 61001 g / mole and a degree of polymerization distribution index (PDI) (Mw / Mn) of 1.03.

[0184] In the reaction mixture containing low-cis polybutadiene rubber (LCBR) and cyclohexane obtained as described above, 38.1 g of dibenzyl peroxide [Perkadox 1-W75(BPO)] and 31.5 g of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy (4OH-TEMPO) were added. The mixture thus obtained was kept at a constant temperature of 105°C and stirred at that temperature for 3 hours until the low-cis polybutadiene rubber (LCBR) chain was functionalized with 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy (4OH-TEMPO).

[0185] The molecular weight distribution of functionalized low-cis polybutadiene rubber (LCBR) samples was determined by gel permeation chromatography (GPC) as described above, yielding a weight-average molecular weight (Mw) of 61256 g / mole and a degree of polymerization distribution index (PDI) (Mw / Mn) of 1.03.

[0186] The functionalized low-cis polybutadiene rubber (LCBR) solution obtained as described above was transferred to an 800-liter batch pressure cooker equipped with a temperature controller, stirring system, vacuum control system, and condensate collection system. The pressure cooker was maintained at a constant temperature of 25°C and placed under a vacuum of 70 mbar. Once liquid was observed in the condensate collection system, 248.8 kg of styrene was slowly added while the temperature of the pressure cooker was increased to a maximum of 66°C. The solvent exchange operation was completed once 313.7 kg of condensate had been collected. The concentration of cyclohexane in the styrene solution was less than 500 ppm. The final solution was stored in a buffer tank, and at the end of the solvent exchange operation, the concentration of the functionalized low-cis polybutadiene rubber (LCBR) in the styrene was equal to 27.0%.

[0187] A 16.5 kg equivalent of functionalized low-cis polybutadiene rubber (LCBR) in styrene at a concentration of 27.0% was transferred into a 50-liter vessel equipped with a stirrer. The following were then fed into the vessel: 9.8 kg styrene, 3.7 kg ethylbenzene, 11.5 g di-1,1-bis(tert-butylperoxy)cyclohexane [Trigonox 22-E50 (Tx22E50)] (free radical initiator), 55.6 g octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Irganox® 1076) (antioxidant), and 17.0 g n-dodecyl mercaptan (NDM) chain transfer agent. The resulting solution was continuously fed at a flow rate of 3.8 kg / h into a first 10-liter plug flow reactor (PFR) (R1) equipped with a stirrer and temperature control system. Acrylonitrile was immediately added to the solution at a flow rate of 0.7 kg / h before entering the first plug flow reactor (PFR)(R1). The thermal profile of this reactor increased from 113°C to 122°C while the stirring speed remained constant at 80 rpm. In the first plug flow reactor (PFR)(R1), the prepolymerization, grafting, and phase inversion were carried out. The mixture leaving the plug flow reactor (PFR)(R1) was continuously added (0.15 kg / h) of a n-dodecyl mercaptan (NDM) chain transfer agent solution in ethylbenzene (EB) [45.0 g NDM in 0.955 kg (EB), corresponding to a NDM concentration of 4.5% in ethylbenzene], and fed into a second plug flow reactor (PFR)(R2), which was also equipped with a stirrer and a temperature control system, wherein the thermal profile of this reactor increased from 139°C to 150°C while the stirring speed remained constant at 10 rpm.

[0188] The obtained mixture was fed into a devolatilizer operating at 255°C under vacuum to remove unreacted styrene and solvent from the copolymer, thereby obtaining the final copolymer. The reaction conditions used in this method are reported in Table 1b. The characteristics of the obtained product are shown in Table 2b. [Example] [7(] [For comparison] [)]

[0189] In a nitrogen stream, the following feed is sequentially introduced into a 300-liter reactor, which is kept anhydrous, equipped with a stirrer, and a heated shroud in which through-heated oil at 50°C is circulated: 124.4 kg of anhydrous cyclohexane, 22.0 kg of anhydrous butadiene without inhibitors and alkynes, and, when the reaction mixture has reached a temperature of 40°C, 1208.0 g of a 2% by weight n-butyllithium (nBL) solution in cyclohexane. After the conversion is complete, the reaction mixture is fed at 115°C into a second 300-liter reactor equipped with a stirrer and a heated shroud in which through-heated oil at 25°C is circulated, and at the same time, an equivalent amount of 22.0 g of ethanol is introduced to complete the chain termination.

[0190] A low-cis polybutadiene rubber (LCBR) sample was subjected to gel permeation chromatography (GPC) as reported above to determine its molecular weight distribution. The weight-average molecular weight (Mw) was 60,986 g / mole and the degree of polymerization distribution index (PDI) (Mw / Mn) was 1.03.

[0191] In the reaction mixture containing low-cis polybutadiene rubber (LCBR) and cyclohexane obtained as described above, 38.1 g of dibenzyl peroxide [Perkadox 1-W75(BPO)] and 31.5 g of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy (4OH-TEMPO) were added. The mixture thus obtained was kept at a constant temperature of 105°C and stirred at this temperature for 3 hours until the low-cis polybutadiene rubber (LCBR) chain was functionalized with 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy (4OH-TEMPO).

[0192] The molecular weight distribution of functionalized low-cis polybutadiene rubber (LCBR) samples was determined by gel permeation chromatography (GPC) as described above, yielding a weight-average molecular weight (Mw) of 60,138 g / mole and a degree of polymerization distribution index (PDI) (Mw / Mn) of 1.02.

[0193] The functionalized low-cis polybutadiene rubber (LCBR) solution obtained as described above was transferred to an 800-liter batch pressure cooker equipped with a temperature controller, stirring system, vacuum control system, and condensate collection system. The pressure cooker was maintained at a constant temperature of 25°C and placed under a vacuum of 70 mbar. Once liquid was observed in the condensate collection system, 248.8 kg of styrene was slowly added while the temperature of the pressure cooker was increased to a maximum of 66°C. The solvent exchange operation was completed once 314.6 kg of condensate had been collected. The concentration of cyclohexane in the styrene solution was less than 500 ppm. The final solution was stored in a buffer tank, and at the end of the solvent exchange operation, the concentration of the functionalized low-cis polybutadiene rubber (LCBR) in styrene was equal to 27.3%.

[0194] A 16.3 kg equivalent of functionalized low-cis polybutadiene rubber (LCBR) comprising 27.3% styrene was transferred to a 50-liter vessel equipped with a stirrer, into which the following were subsequently fed: 10.0 kg styrene, 3.7 kg ethylbenzene, 11.5 g di-1,1-bis(tert-butylperoxy)cyclohexane [Trigonox 22-E50 (Tx22E50)] (free radical initiator), 55.6 g octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Irganox® 1076) (antioxidant), and 22.2 g n-dodecyl mercaptan (NDM) chain transfer agent. The resulting solution was continuously fed at a flow rate of 3.8 kg / h into a first 10-liter plug flow reactor (PFR) (R1) equipped with a stirrer and a temperature control system. Acrylonitrile was immediately added to the solution at a flow rate of 0.7 kg / h before entering the first plug flow reactor (PFR)(R1). The thermal profile of this reactor increased from 113°C to 122°C while the stirring speed remained constant at 80 rpm. In the first plug flow reactor (PFR)(R1), the prepolymerization, grafting, and phase inversion were carried out. The mixture leaving the plug flow reactor (PFR)(R1) was continuously added (0.15 kg / h) of a n-dodecyl mercaptan (NDM) chain transfer agent solution in ethylbenzene (EB) [39.0 g NDM in 0.961 kg (EB), corresponding to a NDM concentration of 3.9% in ethylbenzene], and fed into a second plug flow reactor (PFR)(R2), which was also equipped with a stirrer and a temperature control system, wherein the thermal profile of this reactor increased from 139°C to 150°C while the stirring speed remained constant at 10 rpm.

[0195] The obtained mixture was fed into a devolatilizer operating at 255°C under vacuum to remove unreacted styrene and solvent from the copolymer, thereby obtaining the final copolymer. The reaction conditions used in this method are reported in Table 1b. The characteristics of the obtained product are shown in Table 2b. [Example] [8(] [For comparison] [)]

[0196] In a nitrogen stream, the following feedstock is sequentially introduced into a 300-liter reactor, kept anhydrous and equipped with a stirrer and a heated shroud in which permeable oil at 50°C is circulated: 124.4 kg of anhydrous cyclohexane, 22.0 kg of anhydrous butadiene without inhibitors and alkynes, and, when the reaction mixture has reached a temperature of 40°C, 967.0 g of a 2% by weight n-butyllithium (nBL) solution in cyclohexane. After conversion, at a temperature of 113°C, the reaction mixture is fed into a second 300-liter reactor equipped with a stirrer and a heated shroud in which permeable oil at 25°C is circulated, and at the same time, an equal amount of 18.0 g of ethanol is introduced to complete the chain termination.

[0197] A low-cis polybutadiene rubber (LCBR) sample was subjected to gel permeation chromatography (GPC) as reported above to determine its molecular weight distribution. The weight-average molecular weight (Mw) was 73,791 g / mole and the degree of polymerization distribution index (PDI) (Mw / Mn) was 1.03.

[0198] In the reaction mixture containing low-cis polybutadiene rubber (LCBR) and cyclohexane obtained as described above, 30.5 g of dibenzyl peroxide [Perkadox 1-W75(BPO)] and 25.2 g of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy (4OH-TEMPO) were added. The mixture thus obtained was kept at a constant temperature of 105°C and stirred at that temperature for 3 hours until the low-cis polybutadiene rubber (LCBR) chain was functionalized with 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy (4OH-TEMPO).

[0199] The molecular weight distribution of functionalized low-cis polybutadiene rubber (LCBR) samples was determined by gel permeation chromatography (GPC) as described above, yielding a weight-average molecular weight (Mw) of 73,578 g / mole and a degree of polymerization distribution index (PDI) (Mw / Mn) of 1.04.

[0200] The functionalized low-cis polybutadiene rubber (LCBR) solution obtained as described above was transferred to an 800-liter batch pressure cooker equipped with a temperature controller, stirring system, vacuum control system, and condensate collection system. The pressure cooker was maintained at a constant temperature of 25°C and placed under a vacuum of 70 mbar. Once liquid was observed in the condensate collection system, 248.8 kg of styrene was slowly added while the temperature of the pressure cooker was increased to a maximum of 66°C. The solvent exchange operation was completed once 303.9 kg of condensate had been collected. The concentration of cyclohexane in the styrene solution was less than 500 ppm. The final solution was stored in a buffer tank, and at the end of the solvent exchange operation, the concentration of the functionalized low-cis polybutadiene rubber (LCBR) in the styrene was equal to 24.1%.

[0201] An equal amount of 18.5 kg of functionalized low-cis polybutadiene rubber (LCBR) comprising 24.1% styrene was transferred to a 50-liter vessel equipped with a stirrer, into which the following were subsequently fed: 7.8 kg styrene, 3.7 kg ethylbenzene, 11.5 g di-1,1-bis(tert-butylperoxy)cyclohexane [Trigonox 22-E50 (Tx22E50)] (free radical initiator), 55.6 g octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Irganox® 1076) (antioxidant), and 5.6 g n-dodecyl mercaptan (NDM) chain transfer agent. The resulting solution was continuously fed at a flow rate of 3.8 kg / h into a first 10-liter plug flow reactor (PFR) (R1) equipped with a stirrer and a temperature control system. Acrylonitrile was immediately added to the solution at a flow rate of 0.7 kg / h before entering the first plug flow reactor (PFR)(R1). The thermal profile of this reactor increased from 113°C to 122°C while the stirring speed remained constant at 80 rpm. In the first plug flow reactor (PFR)(R1), the prepolymerization, grafting, and phase inversion were carried out. The mixture leaving the plug flow reactor (PFR)(R1) was continuously added (0.15 kg / h) of a n-dodecyl mercaptan (NDM) chain transfer agent solution in ethylbenzene (EB) [45.0 g NDM in 0.955 kg (EB), corresponding to a NDM concentration of 4.5% in ethylbenzene], and fed into a second plug flow reactor (PFR)(R2), which was also equipped with a stirrer and a temperature control system, wherein the thermal profile of this reactor increased from 139°C to 150°C while the stirring speed remained constant at 10 rpm.

[0202] The obtained mixture was fed into a devolatilizer operating at 255°C under vacuum to remove unreacted styrene and solvent from the copolymer, thereby obtaining the final copolymer. The reaction conditions used in this method are reported in Table 1c. The characteristics of the obtained product are shown in Table 2c. [Example] [9(] [invention] [)]

[0203] In a nitrogen stream, the following feedstock is sequentially introduced into a 300-liter reactor, kept anhydrous and equipped with a stirrer and a heated shroud in which permeable oil at 50°C is circulated: 124.4 kg of anhydrous cyclohexane, 22.0 kg of anhydrous butadiene without inhibitors and alkynes, and, when the reaction mixture has reached a temperature of 40°C, 967.0 g of a 2% by weight n-butyllithium (nBL) solution in cyclohexane. After conversion, at a temperature of 113°C, the reaction mixture is fed into a second 300-liter reactor equipped with a stirrer and a heated shroud in which permeable oil at 25°C is circulated, and at the same time, an equal amount of 18.0 g of ethanol is introduced to complete the chain termination.

[0204] A low-cis polybutadiene rubber (LCBR) sample was subjected to gel permeation chromatography (GPC) as reported above to determine its molecular weight distribution. The weight-average molecular weight (Mw) was 78,736 g / mole and the degree of polymerization distribution index (PDI) (Mw / Mn) was 1.05.

[0205] In the reaction mixture containing polybutadiene (LCBR) and cyclohexane obtained as described above, 30.5 g of dibenzyl peroxide [Perkadox 1-W75(BPO)] and 25.2 g of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy (4OH-TEMPO) were added. The mixture thus obtained was kept at a constant temperature of 105°C and stirred at this temperature for 3 hours until the low-cis polybutadiene rubber (LCBR) chain was functionalized with 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy (4OH-TEMPO).

[0206] The molecular weight distribution of functionalized low-cis-butadiene rubber (LCBR) samples was determined by gel permeation chromatography (GPC) as described above, yielding a weight-average molecular weight (Mw) of 78201 g / mole and a degree of polymerization distribution index (PDI) (Mw / Mn) of 1.04.

[0207] The functionalized low-cis polybutadiene rubber (LCBR) solution obtained as described above was transferred to an 800-liter batch pressure cooker equipped with a temperature controller, stirring system, vacuum control system, and condensate collection system. The pressure cooker was maintained at a constant temperature of 25°C and placed under a vacuum of 70 mbar. Once liquid was observed in the condensate collection system, 248.8 kg of styrene was slowly added while the temperature of the pressure cooker was increased to a maximum of 66°C. The solvent exchange operation was completed once 298.7 kg of condensate had been collected. The concentration of cyclohexane in the styrene solution was less than 500 ppm. The final solution was stored in a buffer tank, and at the end of the solvent exchange operation, the concentration of the functionalized low-cis polybutadiene rubber (LCBR) in the styrene was equal to 22.8%.

[0208] A 19.5 kg equivalent of functionalized low-cis polybutadiene rubber (LCBR) comprising 22.8% styrene was transferred to a 50-liter vessel equipped with a stirrer, into which the following were subsequently fed: 6.8 kg styrene, 3.7 kg ethylbenzene, 11.5 g 1,1-bis(tert-butylperoxy)cyclohexane [Trigonox 22-E50 (Tx22E50)] (free radical initiator), 55.6 g octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Irganox® 1076) (antioxidant), and 13 g n-dodecyl mercaptan (NDM) chain transfer agent. The resulting solution was continuously fed at a flow rate of 3.8 kg / h into a first 10-liter plug flow reactor (PFR) (R1) equipped with a stirrer and a temperature control system. Acrylonitrile was immediately added to the solution at a flow rate of 0.7 kg / h before entering the first plug flow reactor (PFR)(R1). The thermal profile of this reactor increased from 113°C to 122°C while the stirring speed remained constant at 80 rpm. In the first plug flow reactor (PFR)(R1), the prepolymerization, grafting, and phase inversion were carried out. The mixture leaving the plug flow reactor (PFR)(R1) was continuously added (0.15 kg / h) of a n-dodecyl mercaptan (NDM) chain transfer agent solution in ethylbenzene (EB) [39.0 g NDM in 0.961 kg (EB), corresponding to a NDM concentration of 3.9% in ethylbenzene], and fed into a second plug flow reactor (PFR)(R2), which was also equipped with a stirrer and a temperature control system, wherein the thermal profile of this reactor increased from 139°C to 150°C while the stirring speed remained constant at 10 rpm.

[0209] The obtained mixture was fed into a devolatilizer operating at 255°C under vacuum to remove unreacted styrene and solvent from the copolymer, thereby obtaining the final copolymer. The reaction conditions used in this method are reported in Table 1c. The characteristics of the obtained product are shown in Table 2c. [Example] [10(] [For comparison] [)]

[0210] In a nitrogen stream, the following feedstock is sequentially introduced into a 300-liter reactor, kept anhydrous and equipped with a stirrer and a heated shroud in which permeable oil at 50°C is circulated: 124.4 kg of anhydrous cyclohexane, 22.0 kg of anhydrous butadiene without inhibitors and alkynes, and, when the reaction mixture has reached a temperature of 40°C, 967.0 g of a 2% by weight n-butyllithium (nBL) solution in cyclohexane. After conversion, at a temperature of 113°C, the reaction mixture is fed into a second 300-liter reactor equipped with a stirrer and a heated shroud in which permeable oil at 25°C is circulated, and at this time, an equivalent amount of 51.0 g of heptanoic acid is also introduced to complete the chain termination.

[0211] A low-cis polybutadiene rubber (LCBR) sample was subjected to gel permeation chromatography (GPC) as reported above to determine its molecular weight distribution. The weight-average molecular weight (Mw) was 77,568 g / mole and the degree of polymerization distribution index (PDI) (Mw / Mn) was 1.04.

[0212] In the reaction mixture containing low-cis polybutadiene rubber (LCBR) and cyclohexane obtained as described above, 30.5 g of dibenzyl peroxide [Perkadox 1-W75(BPO)] and 25.2 g of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy (4OH-TEMPO) were added. The mixture thus obtained was kept at a constant temperature of 105°C and stirred at that temperature for 3 hours until the low-cis polybutadiene rubber (LCBR) chain was functionalized with 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy (4OH-TEMPO).

[0213] The molecular weight distribution of functionalized low-cis polybutadiene rubber (LCBR) samples was determined by gel permeation chromatography (GPC) as described above, yielding a weight-average molecular weight (Mw) of 77,853 g / mole and a degree of polymerization distribution index (PDI) (Mw / Mn) of 1.05.

[0214] The functionalized low-cis polybutadiene rubber (LCBR) solution obtained as described above was transferred to an 800-liter batch pressure cooker equipped with a temperature controller, stirring system, vacuum control system, and condensate collection system. The pressure cooker was maintained at a constant temperature of 25°C and placed under a vacuum of 70 mbar. Once liquid was observed in the condensate collection system, 248.8 kg of styrene was slowly added while the temperature of the pressure cooker was increased to a maximum of 66°C. The solvent exchange operation was completed once 302.0 kg of condensate had been collected. The concentration of cyclohexane in the styrene solution was less than 500 ppm. The final solution was stored in a buffer tank, and at the end of the solvent exchange operation, the concentration of the functionalized low-cis polybutadiene rubber (LCBR) in the styrene was equal to 23.7%.

[0215] A 19.2 kg equivalent of functionalized low-cis polybutadiene rubber (LCBR) comprising 23.7% styrene was transferred to a 50-liter vessel equipped with a stirrer, into which the following were subsequently fed: 7.4 kg styrene, 3.7 kg ethylbenzene, 11.5 g di-1,1-bis(tert-butylperoxy)cyclohexane [Trigonox 22-E50 (Tx22E50)] (free radical initiator), 55.6 g octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Irganox® 1076) (antioxidant), and 16.7 g n-dodecyl mercaptan (NDM) chain transfer agent. The resulting solution was continuously fed at a flow rate of 3.8 kg / h into a first 10-liter plug flow reactor (PFR) (R1) equipped with a stirrer and a temperature control system. Acrylonitrile was immediately added to the solution at a flow rate of 0.7 kg / h before entering the first plug flow reactor (PFR)(R1). The thermal profile of this reactor increased from 113°C to 122°C while the stirring speed remained constant at 80 rpm. In the first plug flow reactor (PFR)(R1), the prepolymerization, grafting, and phase inversion were carried out. The mixture leaving the plug flow reactor (PFR)(R1) was continuously added (0.15 kg / h) of a n-dodecyl mercaptan (NDM) chain transfer agent solution in ethylbenzene (EB) [33.0 g NDM in 0.967 kg (EB), corresponding to a NDM concentration of 3.3% in ethylbenzene], and fed into a second plug flow reactor (PFR)(R2), which was also equipped with a stirrer and a temperature control system, wherein the thermal profile of this reactor increased from 139°C to 150°C while the stirring speed remained constant at 10 rpm.

[0216] The obtained mixture was fed into a devolatilizer operating at 255°C under vacuum to remove unreacted styrene and solvent from the copolymer, thereby obtaining the final copolymer. The reaction conditions used in this method are reported in Table 1c. The characteristics of the obtained product are shown in Table 2c. [Example] [11(] [For comparison] [)]

[0217] In a nitrogen stream, the following feedstock is sequentially introduced into a 300-liter reactor, kept anhydrous and equipped with a stirrer and a heated shroud in which permeable oil at 50°C is circulated: 124.4 kg of anhydrous cyclohexane, 22.0 kg of anhydrous butadiene without inhibitors and alkynes, and, when the reaction mixture has reached a temperature of 40°C, 806.0 g of a 2% by weight n-butyllithium (nBL) solution in cyclohexane. After conversion, at a temperature of 113°C, the reaction mixture is fed into a second 300-liter reactor equipped with a stirrer and a heated shroud in which permeable oil at 25°C is circulated, and at the same time, an equivalent amount of 15.0 g of ethanol is introduced to complete the chain termination.

[0218] A low-cis polybutadiene rubber (LCBR) sample was subjected to gel permeation chromatography (GPC) as reported above to determine its molecular weight distribution. The weight-average molecular weight (Mw) was 89,882 g / mole and the degree of polymerization distribution index (PDI) (Mw / Mn) was 1.05.

[0219] In the reaction mixture containing low-cis polybutadiene rubber (LCBR) and cyclohexane obtained as described above, 25.4 g of dibenzyl peroxide [Perkadox 1-W75(BPO)] and 21.0 g of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy (4OH-TEMPO) were added. The mixture thus obtained was kept at a constant temperature of 105°C and stirred at that temperature for 3 hours until the low-cis polybutadiene rubber (LCBR) chain was functionalized with 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy (4OH-TEMPO).

[0220] The molecular weight distribution of functionalized low-cis polybutadiene rubber (LCBR) samples was determined by gel permeation chromatography (GPC) as described above, yielding a weight-average molecular weight (Mw) of 90026 g / mole and a degree of polymerization distribution index (PDI) (Mw / Mn) of 1.06.

[0221] The functionalized low-cis polybutadiene rubber (LCBR) solution obtained as described above was transferred to an 800-liter batch pressure cooker equipped with a temperature controller, stirring system, vacuum control system, and condensate collection system. The pressure cooker was maintained at a constant temperature of 25°C and placed under a vacuum of 70 mbar. Once liquid was observed in the condensate collection system, 248.8 kg of styrene was slowly added while the temperature of the pressure cooker was increased to a maximum of 66°C. The solvent exchange operation was completed once 291.4 kg of condensate had been collected. The concentration of cyclohexane in the styrene solution was less than 500 ppm. The final solution was stored in a buffer tank, and at the end of the solvent exchange operation, the concentration of the functionalized low-cis polybutadiene rubber (LCBR) in the styrene was equal to 21.2%.

[0222] A 21.0 kg equivalent of functionalized low-cis polybutadiene rubber (LCBR) comprising 21.2% styrene was transferred to a 50-liter vessel equipped with a stirrer, into which the following were subsequently fed: 5.3 kg styrene, 3.7 kg ethylbenzene, 11.5 g di-1,1-bis(tert-butylperoxy)cyclohexane [Trigonox 22-E50 (Tx22E50)] (free radical initiator), 55.6 g octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Irganox® 1076) (antioxidant), and 5.6 g n-dodecyl mercaptan (NDM) chain transfer agent. The resulting solution was continuously fed at a flow rate of 3.8 kg / h into a first 10-liter plug flow reactor (PFR) (R1) equipped with a stirrer and a temperature control system. Acrylonitrile was immediately added to the solution at a flow rate of 0.7 kg / h before entering the first plug flow reactor (PFR)(R1). The thermal profile of this reactor increased from 113°C to 122°C while the stirring speed remained constant at 80 rpm. In the first plug flow reactor (PFR)(R1), the prepolymerization, grafting, and phase inversion were carried out. The mixture leaving the plug flow reactor (PFR)(R1) was continuously added (0.15 kg / h) of a n-dodecyl mercaptan (NDM) chain transfer agent solution in ethylbenzene (EB) [45.0 g NDM in 0.955 kg (EB), corresponding to a NDM concentration of 4.5% in ethylbenzene], and fed into a second plug flow reactor (PFR)(R2), which was also equipped with a stirrer and a temperature control system, wherein the thermal profile of this reactor increased from 139°C to 150°C while the stirring speed remained constant at 10 rpm.

[0223] The obtained mixture was fed into a devolatilizer operating at 255°C under vacuum to remove unreacted styrene and solvent from the copolymer, thereby obtaining the final copolymer. The reaction conditions used in this method are reported in Table 1d. The characteristics of the obtained product are shown in Table 2d. [Example] [12(] [invention] [)]

[0224] In a nitrogen stream, the following feedstock is sequentially introduced into a 300-liter reactor, kept anhydrous and equipped with a stirrer and a heated shroud in which permeable oil at 50°C is circulated: 124.4 kg of anhydrous cyclohexane, 22.0 kg of anhydrous butadiene without inhibitors and alkynes, and, when the reaction mixture has reached a temperature of 40°C, 806.0 g of a 2% by weight n-butyllithium (nBL) solution in cyclohexane. After conversion, at a temperature of 110°C, the reaction mixture is fed into a second 300-liter reactor equipped with a stirrer and a heated shroud in which permeable oil at 25°C is circulated, and at this time, an equivalent amount of 42.0 g of heptanoic acid is also introduced to complete the chain termination.

[0225] A low-cis polybutadiene rubber (LCBR) sample was subjected to gel permeation chromatography (GPC) as reported above to determine its molecular weight distribution. The weight-average molecular weight (Mw) was 90,566 g / mole and the degree of polymerization distribution index (PDI) (Mw / Mn) was 1.06.

[0226] In the reaction mixture containing low-cis polybutadiene rubber (LCBR) and cyclohexane obtained as described above, 25.4 g of dibenzyl peroxide [Perkadox 1-W75(BPO)] and 21.0 g of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy (4OH-TEMPO) were added. The mixture thus obtained was kept at a constant temperature of 105°C and stirred at that temperature for 3 hours until the low-cis polybutadiene rubber (LCBR) chain was functionalized with 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy (4OH-TEMPO).

[0227] The molecular weight distribution of functionalized low-cis polybutadiene rubber (LCBR) samples was determined by gel permeation chromatography (GPC) as described above, yielding a weight-average molecular weight (Mw) of 89,823 g / mole and a degree of polymerization distribution index (PDI) (Mw / Mn) of 1.05.

[0228] The functionalized low-cis polybutadiene rubber (LCBR) solution obtained as described above was transferred to an 800-liter batch pressure cooker equipped with a temperature controller, stirring system, vacuum control system, and condensate collection system. The pressure cooker was maintained at a constant temperature of 25°C and placed under a vacuum of 70 mbar. Once liquid was observed in the condensate collection system, 248.8 kg of styrene was slowly added while the temperature of the pressure cooker was increased to a maximum of 66°C. Once 292.9 kg of condensate had been collected, the solvent exchange operation was complete. The concentration of cyclohexane in the styrene solution was less than 500 ppm. The final solution was stored in a buffer tank, and at the end of the solvent exchange operation, the concentration of the functionalized low-cis polybutadiene rubber (LCBR) in the styrene was equal to 21.5%.

[0229] A 20.7 kg equivalent of functionalized low-cis polybutadiene rubber (LCBR) comprising 21.5% styrene was transferred to a 50-liter vessel equipped with a stirrer, into which the following were subsequently fed: 5.6 kg styrene, 3.7 kg ethylbenzene, 11.5 g di-1,1-bis(tert-butylperoxy)cyclohexane [Trigonox 22-E50 (Tx22E50)] (free radical initiator), 55.6 g octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Irganox® 1076) (antioxidant), and 9.3 g n-dodecyl mercaptan (NDM) chain transfer agent. The resulting solution was continuously fed at a flow rate of 3.8 kg / h into a first 10-liter plug flow reactor (PFR) (R1) equipped with a stirrer and a temperature control system. Acrylonitrile was immediately added to the solution at a flow rate of 0.7 kg / h before entering the first plug flow reactor (PFR)(R1). The thermal profile of this reactor increased from 113°C to 122°C while the stirring speed remained constant at 80 rpm. In the first plug flow reactor (PFR)(R1), the prepolymerization, grafting, and phase inversion were carried out. The mixture leaving the plug flow reactor (PFR)(R1) was continuously added (0.15 kg / h) of a n-dodecyl mercaptan (NDM) chain transfer agent solution in ethylbenzene (EB) [45.0 g NDM in 0.955 kg (EB), corresponding to a NDM concentration of 4.5% in ethylbenzene], and fed into a second plug flow reactor (PFR)(R2), which was also equipped with a stirrer and a temperature control system, wherein the thermal profile of this reactor increased from 139°C to 150°C while the stirring speed remained constant at 10 rpm.

[0230] The obtained mixture was fed into a devolatilizer operating at 255°C under vacuum to remove unreacted styrene and solvent from the copolymer, thereby obtaining the final copolymer. The reaction conditions used in this method are reported in Table 1c. The characteristics of the obtained product are shown in Table 2d. [Example] [13(] [For comparison] [)]

[0231] In a nitrogen stream, the following feedstock is sequentially introduced into a 300-liter reactor, kept anhydrous and equipped with a stirrer and a heated shroud in which permeable oil at 50°C is circulated: 124.4 kg of anhydrous cyclohexane, 22.0 kg of anhydrous butadiene without inhibitors and alkynes, and, when the reaction mixture has reached a temperature of 40°C, 806.0 g of a 2% by weight n-butyllithium (nBL) solution in cyclohexane. After conversion, at a temperature of 110°C, the reaction mixture is fed into a second 300-liter reactor equipped with a stirrer and a heated shroud in which permeable oil at 25°C is circulated, and at this time, an equivalent amount of 42.0 g of heptanoic acid is also introduced to complete the chain termination.

[0232] A low-cis polybutadiene rubber (LCBR) sample was subjected to gel permeation chromatography (GPC) as reported above to determine its molecular weight distribution. The weight-average molecular weight (Mw) was 91,156 g / mole and the degree of polymerization distribution index (PDI) (Mw / Mn) was 1.06.

[0233] In the reaction mixture containing low-cis polybutadiene rubber (LCBR) and cyclohexane obtained as described above, 25.4 g of dibenzyl peroxide [Perkadox 1-W75(BPO)] and 21.0 g of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy (4OH-TEMPO) were added. The mixture thus obtained was kept at a constant temperature of 105°C and stirred at that temperature for 3 hours until the low-cis polybutadiene rubber (LCBR) chain was functionalized with 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy (4OH-TEMPO).

[0234] The molecular weight distribution of functionalized low-cis polybutadiene rubber (LCBR) samples was determined by gel permeation chromatography (GPC) as described above, yielding a weight-average molecular weight (Mw) of 90,992 g / mole and a degree of polymerization distribution index (PDI) (Mw / Mn) of 1.06.

[0235] The functionalized low-cis polybutadiene rubber (LCBR) solution obtained as described above was transferred to an 800-liter batch pressure cooker equipped with a temperature controller, stirring system, vacuum control system, and condensate collection system. The pressure cooker was maintained at a constant temperature of 25°C and placed under a vacuum of 70 mbar. Once liquid was observed in the condensate collection system, 248.8 kg of styrene was slowly added while the temperature of the pressure cooker was increased to a maximum of 66°C. The solvent exchange operation was completed once 290.9 kg of condensate had been collected. The concentration of cyclohexane in the styrene solution was less than 500 ppm. The final solution was stored in a buffer tank, and at the end of the solvent exchange operation, the concentration of the functionalized low-cis polybutadiene rubber (LCBR) in the styrene was equal to 21.1%.

[0236] A 21.1 kg equivalent of functionalized low-cis polybutadiene rubber (LCBR) comprising 21.1% of styrene was transferred to a 50-liter vessel equipped with a stirrer, into which the following were subsequently fed: 5.2 kg styrene, 3.7 kg ethylbenzene, 11.5 g di-1,1-bis(tert-butylperoxy)cyclohexane [Trigonox 22-E50 (Tx22E50)] (free radical initiator), 55.6 g octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Irganox® 1076) (antioxidant), and 16.7 g n-dodecyl mercaptan (NDM) chain transfer agent. The resulting solution was continuously fed at a flow rate of 3.8 kg / h into a first 10-liter plug flow reactor (PFR) (R1) equipped with a stirrer and a temperature control system. Acrylonitrile was immediately added to the solution at a flow rate of 0.7 kg / h before entering the first plug flow reactor (PFR)(R1). The thermal profile of this reactor increased from 113°C to 122°C while the stirring speed remained constant at 80 rpm. In the first plug flow reactor (PFR)(R1), the prepolymerization, grafting, and phase inversion were carried out. The mixture leaving the plug flow reactor (PFR)(R1) was continuously added (0.15 kg / h) of a n-dodecyl mercaptan (NDM) chain transfer agent solution in ethylbenzene (EB) [33.0 g NDM in 0.967 kg (EB), corresponding to a NDM concentration of 3.3% in ethylbenzene], and fed into a second plug flow reactor (PFR)(R2), which was also equipped with a stirrer and a temperature control system, wherein the thermal profile of this reactor increased from 139°C to 150°C while the stirring speed remained constant at 10 rpm.

[0237] The obtained mixture was fed into a devolatilizer operating at 255°C under vacuum to remove unreacted styrene and solvent from the copolymer, thereby obtaining the final copolymer. The reaction conditions used in this method are reported in Table 1c. The characteristics of the obtained product are shown in Table 2d. Table 1a Example 1 (For comparison) Example 2 (For comparison) Example 3 (for comparison) Example 4 (For comparison) butadiene Kilogram - 22.0 22.0 22.0 Cyclohexane Kilogram - 124.4 124.4 124.4 nBL @2% gram - 1208.0 967.0 806.0 heptanoic acid gram - - 51.0 42.0 heptanoic acid ppm - - 348 287 ethanol gram - 22.0 - _- ethanol ppm - 150 - _- BPO gram - 0 0 0 BPO ppm - 0 0 0 4OH-TEMPO gram - 0 0 0 4OH-TEMPO ppm - 0 0 0 Styrene and solvent exchange Kilogram - 248.8 248.8 248.8 The condensate collected at the end of solvent exchange Kilogram - 313.1 301.2 289.4 LCBR concentration in styrene % - 26.8 23.4 20.8 LCBR feedstock in styrene Kilogram - 16.6 19.0 21.4 SBR Kilogram 4.9 - - - styrene Kilogram 21.4 9.7 7.3 4.9 Ethylbenzene Kilogram 3.7 3.7 3.7 3.7 Tx22E50 gram 11.5 11.5 11.5 11.5 Tx22E50 ppm 310 310 310 310 NDM in R1 gram 0 0 0 0 NDM in R1 ppm 0 0 0 0 Irganox® 1076 gram 55.6 55.6 55.6 55.6 Irganox® 1076 ppm 1500 1500 1500 1500 Acrylonitrile kg / hour 0.7 0.7 0.7 0.7 The flow rate of the reaction mixture in R1 kg / hour 4.5 4.5 4.5 4.5 T1 in R1 °C 113 113 113 113 T2 in R1 °C 122 122 122 122 R1 mixer speed rpm 80 80 80 80 The concentration of NDM in ethylbenzene at R2. % 6.0 6.0 4.5 4.5 The flow rate of NDM solution in ethylbenzene at point R2 kg / hour 0.15 0.15 0.15 0.15 NDM concentration in R2 ppm 2000 2000 1500 1500 T3 in R2 °C 139 139 139 139 T4 in R2 °C 150 150 150 150 R2 mixer speed rpm 10 10 10 10 Temperature of volatile matter removal °C 255 255 255 255 Table 1b Example 5 (For comparison) Example 6 (invention) Example 7 (For comparison) butadiene Kilogram 22.0 22.0 22.0 Cyclohexane Kilogram 124.4 124.4 124.4 nBL @2% gram 1208.0 1208.0 1208.0 heptanoic acid gram 64.0 - - heptanoic acid ppm 437 - - ethanol gram - 22.0 22.0 ethanol ppm - 150 150 BPO gram 38.1 38.1 38.1 BPO ppm 260 260 260 4OH-TEMPO gram 31.5 31.5 31.5 4OH-TEMPO ppm 215 215 215 Styrene and solvent exchange Kilogram 248.8 248.8 248.8 The condensate collected at the end of solvent exchange Kilogram 315.2 313.7 314.6 Functionalized LCBR concentration in styrene % 27.5 27.0 27.3 Functionalized LCBR feedstock in styrene Kilogram 16.2 16.5 16.3 styrene Kilogram 10.1 9.8 10.0 Ethylbenzene Kilogram 3.7 3.7 3.7 Tx22E50 gram 11.5 11.5 11.5 Tx22E50 ppm 310 310 310 NDM in R1 gram 9.3 17.0 22.2 NDM in R1 ppm 250 450 600 Irganox® 1076 gram 55.6 55.6 55.6 Irganox® 1076 ppm 1500 1500 1500 Acrylonitrile kg / hour 0.7 0.7 0.7 Flow rate of the reaction mixture in R1 kg / hour 4.5 4.5 4.5 T1 in R1 °C 113 113 113 T2 in R1 °C 122 122 122 R1 mixer speed rpm 80 80 80 The concentration of NDM in ethylbenzene at R2. % 5.4 4.5 4.5 The flow rate of NDM solution in ethylbenzene at point R2 kg / hour 0.15 0.15 0.15 NDM concentration in R2 ppm 1800 1500 1300 T3 in R2 °C 139 139 139 T4 in R2 °C 150 150 150 R2 mixer speed rpm 10 10 10 Temperature of volatile matter removal °C 255 255 255 Table 1c Example 8 (For comparison) Example 9 (invention) Example 10 (For comparison) butadiene Kilogram 22.0 22.0 22.0 Cyclohexane Kilogram 124.4 124.4 124.4 nBL @2% gram 967.0 967.0 967.0 heptanoic acid gram - - 51.0 heptanoic acid ppm - - 348 ethanol gram 18.0 18.0 - ethanol ppm 123 123 - BPO gram 30.5 30.5 30.5 BPO ppm 208 208 208 4OH-TEMPO gram 25.2 25.2 25.2 4OH-TEMPO ppm 172 172 172 Styrene exchange with solvent Kilogram 248.8 248.8 248.8 The condensate collected at the end of solvent exchange Kilogram 303.9 298.7 302.0 Functionalized LCBR concentration in styrene % 24.1 22.8 23.7 Functionalized LCBR feedstock in styrene Kilogram 18.5 19.5 19.2 styrene Kilogram 7.8 6.8 7.4 Ethylbenzene Kilogram 3.7 3.7 3.7 Tx22E50 gram 11.5 11.5 11.5 Tx22E50 ppm 310 310 310 NDM in R1 gram 5.6 13.0 16.7 NDM in R1 ppm 150 350 450 Irganox® 1076 gram 55.6 55.6 55.6 Irganox® 1076 ppm 1500 1500 1500 Acrylonitrile kg / hour 0.7 0.7 0.7 The flow rate of the reaction mixture in R1 kg / hour 4.5 4.5 4.5 T1 in R1 °C 113 113 113 T2 in R1 °C 122 122 122 R1 mixer speed rpm 80 80 80 The concentration of NDM in ethylbenzene at R2. % 4.5 3.9 3.3 The flow rate of NDM solution in ethylbenzene at point R2 kg / hour 0.15 0.15 0.15 NDM concentration in R2 ppm 1500 1300 1100 T3 in R2 °C 139 139 139 T4 in R2 °C 150 150 150 R2 mixer speed rpm 10 10 10 Temperature of volatile matter removal °C 255 255 255 Table 1d Example 11 (For comparison) Example 12 (invention) Example 13 (For comparison) butadiene Kilogram 22.0 22.0 22.0 Cyclohexane Kilogram 124.4 124.4 124.4 nBL @2% gram 806.0 806.0 806.0 heptanoic acid gram - 42.0 42.0 heptanoic acid ppm - 287 287 ethanol gram 15.0 - - ethanol ppm 102 - - BPO gram 25.4 25.4 25.4 BPO ppm 173 173 173 4OH-TEMPO gram 21.0 21.0 21.0 4OH-TEMPO ppm 143 143 143 Styrene and solvent exchange Kilogram 248.8 248.8 248.8 The condensate collected at the end of solvent exchange Kilogram 291.4 292.9 290.9 Functionalized LCBR concentration in styrene % 21.2 21.5 21.1 Functionalized LCBR feedstock in styrene Kilogram 21.0 20.7 21.1 styrene Kilogram 5.3 5.6 5.2 Ethylbenzene Kilogram 3.7 3.7 3.7 Tx22E50 gram 11.5 11.5 11.5 Tx22E50 ppm 310 310 310 NDM in R1 gram 5.6 9.3 16.7 NDM in R1 ppm 150 250 450 Irganox® 1076 gram 55.6 55.6 55.6 Irganox® 1076 ppm 1500 1500 1500 Acrylonitrile kg / hour 0.7 0.7 0.7 The flow rate of the reaction mixture in R1 kg / hour 4.5 4.5 4.5 T1 in R1 °C 113 113 113 T2 in R1 °C 122 122 122 R1 mixer speed rpm 80 80 80 The concentration of NDM in ethylbenzene at R2. % 4.5 4.5 3.3 The flow rate of NDM solution in ethylbenzene at point R2 kg / hour 0.15 0.15 0.15 NDM concentration in R2 ppm 1500 1500 1100 T3 in R2 °C 139 139 139 T4 in R2 °C 150 150 150 R2 mixer speed rpm 10 10 10 Temperature of volatile matter removal °C 255 255 255 Table 2a Example 1 (for comparison) Example 2 (for comparison) Example 3 (for comparison) Example 4 (for comparison) M w nominal LCBR SBR Europrene SOL B183 60000 75000 90000 NSG - 0 0 0 0 NDM in R1 ppm 0 0 0 0 M wSBR K / Moll 115477 - - - M wLCBR - 60206 77561 91586 M w / M nLCBR - 1.25 1.02 1.04 1.06 1,4-cis LCBR % 40.5 41.2 42.3 42.6 1,4-trans LCBR % 50.6 51.7 50.3 49.7 1,2-Vinyl LCBR % 8.9 7.1 7.4 7.7 PS% in SBR 11.3 - - - LCBR in ABS % 15.3 15.7 14.6 15.2 Acrylonitrile in ABS % 19.5 19.3 20.5 19.7 Inflation index - 13.2 16.0 16.3 13.0 M w in the polymer matrix (SAN) of ABS K / Moll 126588 123584 133183 115243 Mw / Mn of the polymer matrix (SAN) in ABS - 2.74 2.83 3.03 3.24 M w of free SBR in ABS K / Moll 37000 - - - M w of free LCBR in ABS - 21520 26537 29821 M w / M n of free LCBR in ABS - 2.02 1.96 1.96 2.02 Free LCBR in ABS: 1,4-cis % 40.8 41.6 42.6 42.8 Free LCBR in ABS, 1,4-trans % 50.7 51.1 49.9 49.8 Free LCBR of 1,2-vinyl in ABS % 8.5 7.3 7.5 7.4 Average volume diameter of rubber particles micrometer 0.448 0.368 0.450 0.451 The "dispersion factor 1" of the rubber particle diameter - 1.14 1.18 1.23 1.27 The percentage of rubber particles with a volume diameter > 0.40 micrometers % 64.9 26.2 45.1 55.8 Including enclosed particles / unenclosed particles % 2.5 1.0 1.1 1.2 0 0 0 0 MFI@220 °C / 10 kg g / 10 minutes 14.2 12.4 14.2 14.7 Impact resistance: Acrylonitrile @23℃ (ISO 180 / 1A) kilojoules per square meter 16.1 16.1 23.7 17.5 Gloss @20° - 59 63 58 60 Gloss sensitivity - 1.17 1.09 1.33 1.10 elastic modulus Million Basca 2230 2390 2410 2120 elongation at yield % 20.2 14.5 18.8 37.1 Fracture stress Million Basca 33.1 33.8 33.4 29.8 Tapping Stress Million Basca 45.5 49.3 46.2 40.7 Fracture energy joule 17.3 16.1 18.1 17.6 fracture displacement millimeters 10.1 9.8 10.7 10.9 Puncture resistance Joules * millimeters 174.7 157.8 193.7 191.8 cubic micrometer 0 0 0 0 Table 2b Example 5 (for comparison) Example 6 (Invention) Example 7 (for comparison) M w nominal LCBR K / Moll 60000 60000 60000 NSG - 0.5 0.5 0.5 NDM in R1 ppm 250 450 600 M wLCBR K / Moll 59731 61001 60986 M w / M nLCBR - 1.02 1.03 1.03 1,4-cis LCBR % 42.1 42.3 41.9 1,4-trans LCBR % 50.5 50.3 50.9 1,2-Vinyl LCBR % 7.4 7.4 7.2 M w of functionalized LCBR K / Moll 59254 61256 60138 M w / M n of functionalized LCBR - 1.02 1.03 1.02 In functionalized LCBR, 1,4-cis % 43.5 41.8 42.1 In functionalized LCBR, the 1,4-trans % 49.2 50.8 50.8 1,2-vinyl in functionalized LCBR % 7.3 7.4 7.1 Functionalized LCBR in ABS % 15.5 15.4 15.6 Acrylonitrile in ABS % 19.7 19.3 19.4 Inflation index - 17.1 12.2 10.7 M w in the polymer matrix (SAN) of ABS K / Moll 124981 109987 102986 Mw / Mn of the polymer matrix (SAN) in ABS - 2.88 2.33 2.52 M w of free functionalized LCBR in ABS K / Moll 21385 22687 21986 Mw / Mn of free functionalized LCBR in ABS - 1.99 2.01 2.00 Free functionalized LCBR in ABS: 1,4-cis % 42.5 42.5 42.1 1,4-trans-free functionalized LCBR in ABS % 50.1 49.9 50.6 1,2-vinyl-functionalized LCBR in ABS % 7.4 7.6 7.3 Volume diameter of rubber particles micrometer 0.165 0.333 0.482 The "dispersion factor 1" of the rubber particle diameter - 1.13 1.27 1.29 The percentage of rubber particles with a volume diameter > 0.40 micrometers % 0 33.9 48.6 Including enclosed particles / unenclosed particles - 0.1 1.5 2.0 3.3 0.7 0.3 MFI@220 °C / 10 kg g / 10 minutes 11.6 15.7 14.7 Impact resistance: Acrylonitrile @23℃ (ISO 180 / 1A) kilojoules per square meter 3.4 18.0 17.7 Gloss @20° - 78 71 59 Gloss sensitivity - 0.36 0.35 1.14 elastic modulus Million Basca 2310 2180 2030 elongation at yield % 6.9 21.3 22.5 Fracture stress Million Basca 44.4 29.8 30.5 Tapping Stress Million Basca 50.1 41.5 43.4 Fracture energy joule 1.3 29.2 15.8 fracture displacement millimeters 4.2 19.1 11.1 Puncture resistance Joules * millimeters 5.5 557.7 175.4 cubic micrometer 0 0.36 1.22 Table 2c Example 8 (for comparison) Example 9 (Invention) Example 10 (for comparison) M w nominal LCBR K / Moll 75000 75000 75000 NSG - 0.5 0.5 0.5 NDM in R1 ppm 150 350 450 M wLCBR K / Moll 73791 78736 77568 M w / M nLCBR - 1.03 1.05 1.04 1,4-cis LCBR % 42.9 42.5 42.3 1,4-trans LCBR % 49.5 50.2 50.1 1,2-Vinyl LCBR % 7.6 7.3 7.6 M w of functionalized LCBR K / Moll 73578 78201 77853 M w / M n of functionalized LCBR - 1.04 1.04 1.05 In functionalized LCBR, 1,4-cis % 42.2 43.1 42.5 In functionalized LCBR, the 1,4-trans % 50.3 49.3 50.3 1,2-vinyl in functionalized LCBR % 7.5 7.6 7.2 Functionalized LCBR in ABS % 15.4 15.7 15.6 Acrylonitrile in ABS % 19.3 19.2 19.4 Inflation index - 15.3 12.1 14.2 M w in the polymer matrix (SAN) of ABS K / Moll 140770 118392 117123 Mw / Mn of the polymer matrix (SAN) in ABS - 2.88 2.43 2.33 M w of free functionalized LCBR in ABS K / Moll 25842 25981 26087 Mw / Mn of free functionalized LCBR in ABS - 1.93 2.0 1.98 Free functionalized LCBR in ABS: 1,4-cis % 42.8 42.6 42.0 Free functionalized LCBR in ABS, 1,4-trans % 49.4 49.9 50.3 Free functionalized LCBR in ABS: 1,2-vinyl % 7.8 7.5 7.7 Average volume diameter of rubber particles micrometer 0.178 0.332 0.470 The "dispersion factor 1" of the rubber particle diameter - 1.11 1.26 1.29 The percentage of rubber particles with a volume diameter > 0.40 micrometers % 2.6 36.1 53.2 Including enclosed particles / unenclosed particles - 0.1 1.4 2.0 2.0 0.8 0.3 MFI@220 °C / 10 kg g / 10 minutes 9.1 14.2 13.6 Impact resistance: Acrylonitrile @23℃ (ISO 180 / 1A) kilojoules per square meter 3.5 18.9 19.2 Gloss @20° - 72 70 58 Gloss sensitivity - 0.35 0.31 1.20 elastic modulus Million Basca 2360 2170 2120 elongation at yield % 5.7 18.7 21.1 Fracture stress Million Basca 39.0 33.0 32.5 Tapping Stress Million Basca 48.9 44.7 45.0 Fracture energy joule 1.2 30.9 16.9 fracture displacement millimeters 4.1 19.8 10.2 Puncture resistance Joules * millimeters 4.9 611.8 172.4 cubic micrometer 0.06 0.43 1.29 Table 2d Example 11 (for comparison) Example 12 (Invention) Example 13 (for comparison) M w nominal LCBR K / Moll 90000 90000 90000 NSG - 0.5 0.5 0.5 NDM in R1 ppm 150 250 450 M wLCBR K / Moll 89882 90566 91156 M w / M nLCBR - 1.05 1.06 1.06 1,4-cis LCBR % 42.8 43.1 42.1 1,4-trans LCBR % 49.4 49.4 50.6 1,2-Vinyl LCBR % 7.8 7.5 7.3 M w of functionalized LCBR K / Moll 90026 89823 90992 M w / M n of functionalized LCBR - 1.06 1.05 1.06 In functionalized LCBR, 1,4-cis % 42.5 42.9 42.5 1,4-trans in functionalized LCBR % 49.8 49.4 50.3 1,2-vinyl in functionalized LCBR % 7.7 7.7 7.2 Functionalized LCBR in ABS % 15.4 15.6 15.4 Acrylonitrile in ABS % 19.1 19.4 19.3 Inflation index - 13.7 10.9 10.6 M w in the polymer matrix (SAN) of ABS K / Moll 126340 124393 109794 Mw / Mn of the polymer matrix (SAN) in ABS - 3,14 2,86 2,54 M w of free functionalized LCBR in ABS K / Moll 30856 30256 30225 Mw / Mn of free functionalized LCBR in ABS - 2.03 1.99 2.03 Free functionalized LCBR in ABS: 1,4-cis % 42.5 42.8 42.6 Free functionalized LCBR in ABS, 1,4-trans % 49.8 49.5 49.8 Free functionalized LCBR in ABS: 1,2-vinyl % 7.7 7.7 7.6 Average volume diameter of rubber particles micrometer 0.195 0.298 0.485 The "dispersion factor 1" of the rubber particle diameter - 1.11 1.21 1.33 The percentage of rubber particles with a volume diameter > 0.40 micrometers % 1.3 30.9 63.7 Including enclosed particles / unenclosed particles - 0.1 1.5 2.1 1.8 0.9 0.4 MFI@220 °C / 10 kg g / 10 minutes 12.4 13.9 15.5 Impact resistance: Acrylonitrile @23℃ (ISO 180 / 1A) kilojoules per square meter 6.2 17.2 18.1 Gloss @20° - 67 65 58 Gloss sensitivity - 0.36 0.38 1.17 elastic modulus Million Basca 2340 2120 1970 elongation at yield % 11.3 14.4 46.7 Fracture stress Million Basca 34.1 32.5 31.2 Tapping Stress Million Basca 46.7 44.2 38.9 Fracture energy joule 1.2 28.9 17.2 fracture displacement millimeters 4.1 19.6 11.5 Puncture resistance Joules * millimeters 4.9 566.4 197.8 cubic micrometer 0.05 0.028 1.99

[0238] The results shown in Tables 2a-2d are presented below.

[0239] Comparative Examples 1-4 copolymers were obtained that possess only certain properties of the target copolymers of the present invention. These were unfunctionalized styrene-butadiene rubber (SBR) (Comparative Example 1) with a weight average molecular weight (Mw) of 115,447 and unfunctionalized monodisperse low-cis polybutadiene rubber (LCBR) with different weight average molecular weights (Mw), namely 60,206 g / mole in Example 2 (comparative), 77,561 g / mole in Example 3 (comparative), and 91,586 g / mole in Example 4 (comparative). In particular, using unfunctionalized rubber could yield products with good gloss values ​​(i.e., values ​​from 58 to 63) and impact resistance (i.e., values ​​greater than 16 kJ / m²), but with high gloss sensitivity values ​​(i.e., values ​​greater than 1) and low puncture resistance values ​​[i.e., values ​​less than 400 joules per millimeter]. For these copolymers, in fact: - The volume diameter of these particles is too large [greater than 0.37 micrometers, except for Example 2 (for comparison)]; - The percentage of particles with an average volume diameter greater than 0.40 micrometers is too high [greater than 50%, except for Examples 2 (for comparison) and 3 (for comparison)]; - The ratio of particles containing inclusions to particles without inclusions is greater than 1.9, except for Examples 2 (for comparison), 3 (for comparison), and 4 (for comparison).

[0240] It should be noted that the use of functionalized low-cis polybutadiene rubber (LCBR) with functional groups allows for the acquisition of rubber particles with the average volume diameter according to the present invention. It should also be noted that, using rubbers with the same weight-average molecular weight (Mw) (see Tables 2b, 2c, and 2d), the distribution of the average volume diameter of these rubber particles is also observed to be affected by the amount of chain transfer agent n-dodecyl mercaptan (NDM) added before the reverse inversion [i.e., in the first plug flow reactor (PFR)(R1)]. In fact: - In this first plug flow reactor (PFR)(R1), the excessively low amount of n-dodecyl mercaptan (NDM) resulted in LCBR rubber particles having small to medium volume diameters [Examples 5 (comparative), Example 8 (comparative), and Example 11 (comparative)], and therefore products characterized by low impact resistance and low puncture resistance; - By increasing the amount of n-dodecyl mercaptan (NDM) in the first plug flow reactor (PFR)(R1), an increase in the average volume diameter of the LCBR rubber particles has been observed [Examples 6 (Invention), 9 (Invention), and 12 (Invention)], and thus an improvement in mechanical properties [particularly in terms of impact resistance and puncture resistance], without a deterioration in aesthetic properties [particularly in terms of gloss and gloss sensitivity]; - By further increasing the amount of n-dodecyl mercaptan (NDM) in the first plug flow reactor (PFR)(R1), a further increase in the average volume diameter of the LCBR rubber particles can be observed [Example 7 (comparative), Example 10 (comparative) and Example 13 (comparative)], which leads to a deterioration in mechanical properties [especially in terms of puncture resistance and aesthetics].

[0241] It should be noted that the combination of the weight average molecular weight (Mw) of the functionalized low cis polybutadiene rubber (LCBR) used and the weight average molecular weight (Mw) of the styrene-acrylonitrile (SAN) copolymer in reverse reaction [determined by the amount of n-dodecyl mercaptan (NDM) used in the first plug flow reactor (PFR) (R1)] allows for the correct volume distribution of the rubber particles, thus such as the correct percentage of rubber particles with a volume diameter greater than 0.40 micrometers; and the correct ratio (including encapsulated rubber particles / unencapsulated rubber particles).

[0242] Furthermore, the ratio of the aforementioned reports, namely: This condition is satisfied only in the case of rubber-reinforced ethylene aromatic copolymers obtained according to the present invention, as shown in Tables 2a-2d.

[0243] none

Claims

1. A rubber-reinforced ethylene aromatic (co)polymer comprising: (a) a polymer matrix comprising at least one ethylene aromatic monomer and at least one comonomer; (b) rubber particles obtained by a continuous mass process from functionalized low-cis polybutadiene rubber (LCBR) dispersed therein, characterized by the following facts: (i) the average volume diameter of the rubber particles is between 0.27 μm and 0.35 μm; (ii) the volume of rubber particles having a diameter greater than 0.40 μm relative to the total volume of the dispersed rubber particles is between 20% and 50%; (iii) the particle number ratio (including occlusion rubber particles / non-occlusion rubber particles) is between 0.9 and 1.9, wherein: The term includes encapsulated rubber particles as caps and salami, and unencapsulated rubber particles as balls; a cap refers to a rubber particle whose single matrix encapsulation area occupies at least 85% of the particle's total surface area; a salami refers to a rubber particle comprising two or more matrices, wherein in this type of particle, the matrix encapsulation area does not occupy more than 85% of the particle's total surface area; a ball refers to a rubber particle that does not contain any matrix encapsulation.

2. The rubber-reinforced ethylene aromatic (co)polymer of claim 1, wherein the ethylene aromatic monomer is selected from ethylene aromatic monomers having the general formula (I): wherein R is a hydrogen atom or methyl; n is zero or an integer between 1 and 5; and Y is a halogen atom such as chlorine, bromine, or an alkyl or alkoxy group having 1 to 4 carbon atoms.

3. The rubber-reinforced ethylene aromatic (co)polymer of claim 2, wherein the ethylene aromatic monomer having general formula (I) is selected from: styrene, α-methylstyrene, methylstyrene, ethylstyrene, butylstyrene, dimethylstyrene; mono-, di-, tri-, tetra- and penta-chlorostyrene, bromostyrene, methoxystyrene, acetoxystyrene or mixtures thereof.

4. A rubber-reinforced ethylene aromatic (co)polymer of any one of claims 1 to 3, wherein the comonomer system is selected from: (meth)acrylic acid; C1-C4 alkyl esters of (meth)acrylic acid, such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, isopropyl acrylate, butyl acrylate; acetamides and nitriles of (meth)acrylic acid, such as acrylamide, methacrylamide, acrylonitrile, methacrylonitrile; aceimides, such as N-phenylmaleimide; diethylene aromatic monomers, such as divinylbenzene; anhydrides, such as maleic anhydride; or mixtures thereof.

5. A rubber-reinforced ethylene aromatic (co)polymer of any one of claims 1 to 3, wherein the polymer matrix comprises at least one ethylene aromatic monomer and at least one comonomer, and the polymer matrix has a weight average molecular weight (Mw) of less than or equal to 145,000 g / mol.

6. The rubber-reinforced ethylene aromatic (co)polymer of any one of claims 1 to 3, wherein the functionalized low cis polybutadiene rubber (LCBR) is present in the rubber-reinforced ethylene aromatic (co)polymer in an amount between 5% by weight and 35% by weight of the total weight of the rubber-reinforced ethylene aromatic (co)polymer.

7. A rubber-reinforced ethylene aromatic (co)polymer as claimed in any of claims 1 to 3, wherein the rubber particles obtained by a continuous bulk method from functionalized low-cis polybutadiene rubber (LCBR) are obtained from functionalized low-cis polybutadiene rubber (LCBR) having the following characteristics: - Weight average molecular weight (Mw) between 40,000 g / mole and 110,000 g / mole; - Degree of polymerization distribution index (PDI), i.e., the ratio (Mw / Mn) between weight average molecular weight (Mw) and number average molecular weight (Mn) is less than or equal to 1.4; - The isomer composition (microstructure) of the double bonds in the rubber chain is as follows: the content of 1,4-cis units is between 10 wt% and 70 wt%; the content of 1,4-trans units is between 20 wt% and 80 wt%; the content of 1,2-vinyl units is between 0 wt% and 25 wt%; the low cis polybutadiene rubber (LCBR) is functionalized, wherein the functional group can promote controlled chain radical polymerization mediated by a stable free nitroxyl radical; and each rubber polymer chain of the low cis polybutadiene rubber (LCBR) has less than or equal to 1 functional group.

8. A rubber-reinforced ethylene aromatic (co)polymer as claimed in any of claims 1 to 3, wherein in the rubber-reinforced ethylene aromatic (co)polymer: - The weight-average molecular weight (Mw) of the free form of the functionalized low-cis polybutadiene rubber (LCBR) is between 8000 g / mole and 70000 g / mole; - The degree of polymerization distribution index (PDI) of the free form of the functionalized low-cis polybutadiene rubber (LCBR), which is the ratio (Mw / Mn) between the weight-average molecular weight (Mw) and the number-average molecular weight (Mn), is greater than or equal to 1.3; The free form of this functionalized low-cis polybutadiene rubber (LCBR) has the following isomeric composition (microstructure) of double bonds: 1,4-cis units are present in a range of 10% to 70% by weight; 1,4-trans units are present in a range of 20% to 80% by weight; and 1,2-vinyl units are present in a range of 0% to 25% by weight.

9. A rubber-reinforced ethylene aromatic (co)polymer as claimed in any of claims 1 to 3, wherein in the rubber-reinforced ethylene aromatic (co)polymer, the weight-average molecular weight (Mw) of the free functionalized low-cis polybutadiene rubber (LCBR) (Mw LCBRl, in g / mole), the average volume diameter of the rubber particles (Dvm, in micrometers), the volume of rubber particles having a diameter greater than 0.40 micrometers (particles > 0.4 micrometers%), the ratio of the number of encapsulated rubber particles to the number of unencapsulated rubber particles (particle number ratio encapsulated particles / unencapsulated particles), and the weight-average molecular weight (Mw) of the polymer matrix (Mw SAN, in g / mole) are linked by the following relationships: , π is equal to 3.14, and the term NSG is defined according to the following formula: .

10. A rubber-reinforced ethylene aromatic (co)polymer as claimed in any of claims 1 to 3, wherein the rubber-reinforced ethylene aromatic (co)polymer has the following properties: - a gloss value measured at 20°C greater than or equal to 50; - a gloss sensitivity less than or equal to 0.7; - an impact resistance measured at 23°C greater than or equal to 12 kJ / m²; - puncture resistance calculated as the product of fracture displacement (in millimeters) and fracture energy (in joules), which is greater than or equal to 400 joules * millimeters.

11. A method for preparing a rubber-reinforced ethylene aromatic (co)polymer, comprising the following steps: (a) obtaining a functionalized low-cis polybutadiene rubber (LCBR) having a weight average molecular weight (Mw) between 40,000 g / mole and 110,000 g / mole in a low-boiling solvent; (b) discontinuously exchanging the low-boiling solvent with ethylene aromatic monomers; (c) storing a solution of the functionalized low-cis polybutadiene rubber (LCBR) in ethylene aromatic monomers in a buffer tank according to the obtained grade of the functionalized low-cis polybutadiene rubber (LCBR); (d) feeding an equal volume of the solution of the functionalized low-cis polybutadiene rubber (LCBR) in ethylene aromatic monomers stored in the buffer tank into a container, and adding another equal volume of ethylene aromatic monomers to achieve a desired rubber concentration, at least one solvent, at least one free radical polymerization initiator, at least one chain transfer agent, and other known additives in the reaction mixture; (e) The solution obtained in step (d) is continuously fed into a first plug flow reactor (PFR) (R1), and immediately before entering the first reactor (R1), a stream comprising at least one comonomer is fed; (f) the reaction mixture leaving the first reactor (R1) is continuously fed into a second plug flow reactor (PFR) (R2), which is also continuously fed with a solution of at least one chain transfer agent in a solvent; (g) the rubber-reinforced ethylene aromatic (co)polymer is recovered from the polymerization plant; Its characteristics include the following facts: the weight average molecular weight (Mw) of the functionalized low cis polybutadiene rubber (LCBR) (expressed in grams per mole), the amount of chain transfer agent fed into the first plug flow reactor (PFR) (R1) [step (e)] (expressed in ppm, i.e., by weight, the amount of chain transfer agent fed in relation to the total weight of the compound fed in [step (e)]), and the average volume diameter of the functionalized low cis polybutadiene rubber (LCBR) particles (expressed in micrometers) are linked by the following relationship: .

12. The method for preparing rubber-reinforced ethylene aromatic (co)polymers as claimed in claim 11, wherein: - In step (d), the solvent is selected from aromatic solvents, such as ethylbenzene, toluene, xylene, or mixtures thereof; or aliphatic solvents, such as hexane, cyclohexane, or mixtures thereof; or mixtures thereof; and / or - In step (d), the amount of the at least one radical initiator added is between 0% by weight and 0.7% by weight relative to the total weight of the reaction mixture; and / or - In step (d), the at least one radical initiator is selected from those having an activation temperature between 40°C and 170°C, such as 4,4'-bis-(di- Isobutyronitrile), 4,4'-bis(4-cyanopentanoic acid), 2,2'-azobis(2-methylenediamine propane) dihydrochloric acid; peroxides; hydroperoxides; percarbonates; peresters; or mixtures thereof; such as tributyl-isopropyl monoperoxycarbonate, 2-ethylhexyl tributyl monoperoxycarbonate, dibutyl peroxide, di-tert-butyl peroxide, 1,1-di(tert-butylperoxy)cyclohexane, 1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, (di-tert-butylperoxycyclohexane), tributyl peroxyacetate, tributyl peroxide, tributyl peroxybenzoate, tributyl peroxy-2-ethylhexanoate, or mixtures thereof; and / or - In step (d), the amount of the at least one chain transfer agent added is between 0.01% by weight and 1% by weight relative to the total weight of the reaction mixture; and / or - in step (d), the at least one chain transfer agent is selected from thiols, such as n-octylthiol, n-dodecylthiol (NDM), tertiary dodecylthiol, mercaptoethanol, or mixtures thereof; and / or - step (d) is carried out at a temperature between 30°C and 90°C.

13. The method for preparing rubber-reinforced ethylene aromatic (co)polymers as claimed in claim 11 or 12, wherein: - In step (e), the amount of the at least one comonomer added is between 5% by weight and 35% by weight relative to the total weight of the reaction mixture; and / or - step (e) is carried out at a temperature between 100°C and 130°C.

14. The method for preparing rubber-reinforced ethylene aromatic (co)polymers as claimed in claim 11 or 12, wherein: - In step (f), the amount of the at least one chain transfer agent added is between 0.5% by weight and 2.5% by weight relative to the total weight of the reaction mixture; and / or - step (f) is carried out at a temperature between 120°C and 160°C.

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