HK1191661A - Rubber-reinforced vinyl aromatic (co)polymer, having an optimum balance of physico-mechanical properties and a high gloss - Google Patents

Description

Rubber-reinforced vinyl aromatic (co) polymers having an optimum balance of physico-mechanical properties and high gloss

The application is a divisional application of an invention patent application with application number 200980155026.0, which is proposed to the Chinese national patent office on 12, 10 and 2009.

The present invention relates to rubber-reinforced vinyl aromatic (co) polymers having an optimum balance of physical-mechanical properties and high gloss.

More particularly, the present invention relates to vinyl aromatic (co) polymers reinforced with diene rubbers, having optimum physico-mechanical characteristics such as impact resistance, tensile modulus, yield strength, ultimate tensile stress combined with high gloss.

In the present description and claims, the terms rubber and elastomer should be considered as synonyms. All information contained therein should be considered as preferred even when not explicitly stated.

Vinyl aromatic (co) polymers reinforced with rubbers, in particular diene rubbers such as polybutadiene, represent a well-known class of engineering polymers known in the market and widely described in the literature. Specific examples of such (co) polymers are, for example, styrene/acrylonitrile copolymers comprising polybutadiene particles dispersed in a polymer matrix, commonly known as ABS resins, and high impact polystyrene comprising a polystyrene continuous phase in which rubber particles, such as polybutadiene particles, are dispersed, commonly known as HIPS.

It is known that the surface gloss of vinyl aromatic (co) polymers reinforced with rubber particles can be improved by reducing the rubber particle size to values lower than 1 μm. This condition can be achieved by increasing shear during the polymerization reaction. Shear simply refers to the frictional force caused by the agitation of the mixture. The larger the force, the smaller the rubber particle size will be. Since shear is related to the number of revolutions of the stirrer of the polymerization reactor, this feature is an appliance on which certain ranges established by the engine power can be interposed.

Another parameter which can be used to adjust the size of the rubber particles dispersed in the matrix is the reduction of the viscosity in solution of the diene rubber used to prepare the vinylaromatic (co) polymer. However, since diene rubbers such as polybutadiene must have sufficient viscosity to avoid the phenomenon of "cold flow" for the purposes of handling and packaging, it has hitherto been thought impossible to produce reinforced vinyl aromatic (co) polymers having high surface gloss, using in practice solely linear low-viscosity polybutadiene homopolymers as rubbers.

Examples are known in the literature in which the preparation of ABS is described, which have improved aesthetic properties (gloss), using diene rubbers such as polybutadiene, which are modified to reduce the viscosity in solution and are suitable for preparing ABS copolymers with enhanced aesthetic properties. For example:

US patent 4,421,895 describes the use of diene rubbers in the preparation of ABS having a solution viscosity equal to or lower than 80mPa s at 25 ℃ at 5% by weight of styrene. In particular, the diene rubber proposed in this patent is a linear styrene-butadiene block copolymer. With this type of rubber, rubber particles dispersed in the matrix are obtained having a size of less than 0.7 μm, and thus ABS having high aesthetic properties (gloss).

However, an improvement in the surface gloss obtained with the styrene-butadiene linear block copolymer is achieved, compromising other physico-mechanical characteristics, in particular impact resistance. To improve this latter property, keeping the surface gloss substantially unchanged, US patent 4,524,180 describes the preparation of ABS using a mixture of diene rubber (polybutadiene) and a styrene-butadiene linear block copolymer having a low viscosity when measured in a 5% by weight solution in styrene at 25 ℃.

US4,587,294 and 4,639,494 and european patent 277,687 describe the use of star or radial rubbers having a low viscosity when measured in a 5 wt.% solution in styrene at 25 ℃ for the preparation of ABS with enhanced surface gloss. Radial or star rubbers are prepared by means of the known synthesis techniques using lithium-alcohols as initiators for the anionic polymerization of butadiene by: first a linear polymer is prepared having living chain ends with negative charges and Li + as counter-ion, and subsequently a coupling agent, such as silicon tetrachloride, is added, which is capable of reacting with the chain ends and linking the various polymer chains to silicon atoms, for example. Radial or star rubbers allow to obtain copolymers with enhanced gloss, with the same physical-mechanical properties, with respect to other known diene-based rubbers, but they have the drawback of requiring more complex processes for their preparation.

The applicant has now surprisingly found that it is possible to prepare vinylaromatic (co) polymers with enhanced gloss, having the same physical-mechanical characteristics, using diene rubbers as reinforcing elastomers. By using a linear diene rubber with a viscosity (measured in a 5% by weight solution in styrene) equal to (or even higher than) that of the block polybutadiene-polystyrene copolymer or of the radial rubber, i.e. of the diene rubber of the structure described below, it is in fact possible to obtain dispersed rubber particles with smaller dimensions and therefore a final polymer with enhanced aesthetic properties, with the same mechanical properties.

Accordingly, an object of the present invention relates to a rubber-reinforced vinyl aromatic (co) polymer comprising a polymer matrix and a rubber phase consisting of a diene rubber dispersed and/or grafted in the polymer matrix, wherein said rubber phase is selected from at least one of the following:

(i) linear diene rubbers having a solution viscosity of less than 70cPs, preferably 40 to 60 cPs;

(ii) a partial radial diene rubber having a solution viscosity lower than 70cPs, preferably from 40 to 60cPs, in which up to 15% by weight, preferably from 1 to 12%, of the polymer chains are terminated with an amount of tetrafunctional coupling agent (non-limiting example, silicon tetrachloride) to give terminal radial structures of the linear diene rubber chains;

(iii) a trialklene diene rubber having a solution viscosity lower than 70cPs, preferably from 40 to 60cPs, which is a linear diene rubber coupled with a trifunctional agent (a non-limiting example being methyltrichlorosilane having a Si: Li ratio of 1: 3);

(iv) mixtures of linear diene rubber (i) and radial diene rubber (v) in a maximum ratio between them (i)/(v) of 99.5/0.5 to 85/15.

The radial diene rubber (v) may be a commercial radial polybutadiene rubber.

The diene rubber (i), (ii), (iii) or (iv) used for the purposes of the vinylaromatic (co) polymer according to the invention can be natural or synthetic. Suitable synthetic rubbers are those composed of polymers of 1, 3-conjugated dienes containing from 4 to 6 carbon atoms, and in particular polybutadiene, high and medium cis-polybutadiene, polyisoprene.

Particularly preferred is polybutadiene having:

-a solution viscosity of 40-70cPs, preferably 40-60 cPs, measured at 25 ℃ in a 5 wt% solution thereof in styrene;

1,2 vinyl content from 5 to 35, preferably from 7 to 14,% by weight;

a 1, 4-cis content of 20 to 85, preferably 25 to 45% by weight; and

-the molecular structures described in those of (i), (ii), (iii) or (iv).

In particular, the invention relates to:

item 1: rubber-reinforced vinyl aromatic (co) polymer comprising a polymer matrix and a rubber phase of a diene rubber dispersed and/or grafted in the polymer matrix, wherein the rubber phase is selected from at least one of the following:

(i) a linear diene rubber having a solution viscosity of less than 70 cPs;

(ii) a partial radial diene rubber having a solution viscosity lower than 70cPs, in which up to 15% by weight, preferably from 1 to 12%, of the polymer chain ends have an amount of tetrafunctional coupling agent to give a radial terminal structure of linear diene rubber chains;

(iii) a three-branched diene rubber having a solution viscosity lower than 70cPs, which is a linear diene rubber coupled with a trifunctional agent;

(iv) mixtures of linear diene rubber (i) and radial diene rubber (v) having a maximum ratio of (i)/(v) to each other of 99.5/0.5 to 85/15, with a solution viscosity lower than 70 cPs.

Item 2: the vinyl aromatic (co) polymer according to item 1, wherein the diene rubber consists of a polymer of a 1, 3-conjugated diene containing from 4 to 6 carbon atoms.

Item 3: the vinyl aromatic (co) polymer according to item 2, wherein the diene rubber is a polybutadiene having the following characteristics:

a solution viscosity of 40 to 70cPs, preferably 40 to 60cPs, measured at 25 ℃ in a 5 wt% solution in styrene;

1,2 vinyl content of 5 to 35, preferably 7 to 14% by weight;

a 1, 4-cis content of 20-85, preferably 25-45 wt.%; and

(iv) the molecular structures described in (i), (ii), (iii) or (iv).

Item 4. vinyl aromatic copolymer according to any of the preceding claims, comprising acrylic comonomer in an amount of from 5 to 45 wt.%.

Item 5. the vinylaromatic (co) polymer according to any of the previous claims, where the amount of diene rubber (i), (ii), (iii) or (iv) ranges from 4 to 30% by weight.

Item 6. Process for preparing a rubber-reinforced vinylaromatic (co) polymer according to any of claims 1 to 5, which comprises polymerizing at least one vinylaromatic monomer by means of bulk polymerization, solution, emulsion and bulk suspension in the presence of at least one rubber selected from the groups (i) to (iv).

Item 7. use of a rubber-reinforced vinylaromatic (co) polymer according to any of claims 1 to 5 for the preparation of shaped bodies having a gloss at 60 ° higher than 85.

Such polybutadienes are obtained by anionic polymerization of butadiene in solution in aliphatic or cycloaliphatic solvents or mixtures thereof using alkyllithium initiators. The polymerization may be carried out in a batch reactor or a continuous reactor; in a batch reactor, an initiator, usually consisting of primary or sec-butyllithium, is added to the reaction mixture consisting of solvent and monomers, charged in an amount such that the total solids at the end of the polymerization is not higher than 20% by weight; it is known to the expert in the art that the reaction can be carried out in the presence of a higher or lower amount of Lewis base, depending on the content of vinyl groups or 1,2 units to be present in the polymer chain. Ethers are the most widely used lewis base, in particular tetrahydrofuran, already in an amount of 100ppm with respect to the solvent capable of significantly accelerating the reaction, keeping the vinyl unit content at a level of < 12%; with higher amounts of THF, the microstructure gradually changes until the vinyl unit content is higher than 40% for an amount of THF equal to 5,000 ppm. However, if it is not detrimental to the use of polybutadiene in the field of modification of plastic materials, a high vinyl unit content is not required; the content of these units preferably does not exceed a value of 15%, even though for higher grafting efficiencies polybutadienes with a higher content of 1,2 units can be used. The expert in the field also knows that the reaction, carried out in the absence of ether or tertiary amine, is sufficiently rapid to guarantee the complete polymerization of the monomers in a time not longer than 1 hour, the final temperature not higher than 120 ℃ and in any case controlled by the initial temperature of the reaction mixture, which cannot be lower than 35-40 ℃ to avoid an initial reaction that is not sufficiently rapid and incompatible with normal production cycles. The reactor may be equipped with cooling jackets, however these are not particularly effective since the volumes are never less than the unfavourable surface/volume ratio typical of commercial reactors of 20m 3; more efficient temperature control is obtained by means of partial evaporation of the solvent, which is condensed and then fed to the reaction reactor; this type of reactor, known as the "boiling reactor", is very effective for controlling the reaction temperature and represents in the prior art the best way to effectively limit the natural increase in temperature due to the heat of polymerization of butadiene. The polymerization carried out in a batch reactor results in the formation of a polymer having a monomodal molecular weight distribution, before possible addition of a coupling agent, in which the ratio between the weight-average molecular weight (Mw) and the number-average molecular weight (Mn) is very close to 1 and is generally between 1 and 1.2. In contrast, carrying out the polymerization in a continuous reactor of CSTR type or in a plurality of reactors of continuous CSTR type arranged in series results in the formation of a polymer having a monomodal molecular weight distribution with a Mw/Mn ratio of from 1.8 to 2.5, in both cases the polymer being linear at the end of the polymerization and having chain ends which are still living. These chain ends consist of polybutadiene-lithium species. It is possible to add protic reagents (for example alcohols) or silicon halo derivatives, where the ratio between halogen and silicon is equal to 1 (a non-limiting example being trimethylchlorosilane TMCS) causing the butadiene-lithium chain ends to terminate and maintain the linear macrostructure of the molecule. On the other hand, the addition of a polyfunctional substance capable of reacting with the living chain ends results in the formation of branched macrostructures, characterized by nodes, from which a number of branches having the same functionality as the polyfunctional substance used are detached. As a non-limiting example, the use of silicon tetrachloride is known to the expert in the field, which, when added to the reaction environment in a Si: Li ratio of 1:4, results in the formation of a radial polymer having four branches of the same length if the polymer is produced in a batch reactor, whereas in the case of a continuously produced polymer the four branches are different. On the other hand, if the Si: Li ratio is less than 1:4, a partial radial structure (ii) is obtained. If a trifunctional silicon compound is used as coupling agent (a non-limiting example being methyltrichlorosilane), a three-chain rubber (iii) results. The usual polybutadiene production process then involves, after the addition of a pair of antioxidants consisting of a phenolic primary antioxidant and a secondary antioxidant, usually a trivalent phosphorus organic compound, the removal of the solvent by means of the combined action of water and steam in a stirred vessel. This produces a suspension of rubber particles in water, from which, after draining on the wire, the rubber is fed into a drying zone consisting of two mechanical extruders. The extrusion operation was carried out in a first extruder (screw press), which removed most of the water discharged through the side slits of the extruder, while complete drying was carried out in a second extruder (expander), in which the mechanically acting rubber was heated to a temperature of 160 ℃ and 180 ℃. Part of the steam exits through holes (outlets) located at the end of the extruder and part exits at the outlet of the head. The rubber particles are then fed by belts or other conveying means into a packaging machine where they are packaged. The properties of polybutadiene (unsaturated rubber) require a strict control of the final product conditions, since the expert in the field knows the complications resulting from the formation of lumps of insoluble matter (gels) which are usually formed in the final product zone, in particular in the expander. These gels cause a deterioration in the quality of the rubbers intended for the field of modification of plastic materials by forming significant surface defects. Great care must therefore be taken to define the conditions of the finished polybutadiene product, and many analyses must therefore be carried out for process and product control.

The polymer matrix of the rubber-reinforced (co) polymer of the present invention may be a (co) polymer derived from one or more vinyl aromatic monomers, or a (co) polymer derived from one or more vinyl aromatic monomers and one or more comonomers, such as an acrylic comonomer. The term "vinylaromatic monomer" as used in the present description and claims includes ethylenically unsaturated compounds having the general formula

Wherein R represents hydrogen or an alkyl group having 1 to 4 carbon atoms, n is 0 or an integer of 1 to 5, and Y represents halogen or an alkyl group having 1 to 4 carbon atoms. Examples of vinylaromatic monomers having the above-mentioned general formula are: styrene, alpha-methylstyrene, ethylstyrene, butylstyrene, dimethylstyrene, mono-, di-, tri-, tetra-and penta-chlorostyrenes, bromostyrenes, methoxystyrenes, acetoxystyrenes, and the like. Preferred vinylaromatic monomers are styrene and/or alpha-methylstyrene.

The vinylaromatic monomers having the general formula (I) can be used alone or in a mixture of up to 50% by weight with other copolymerizable monomers. Examples of such monomers are (meth) acrylic acid, C of (meth) acrylic acid₁-C₄Alkyl esters such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyleneIsopropyl esters, butyl acrylates, amides and nitriles of (meth) acrylic acid such as acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, butadiene, ethylene, divinylbenzene, maleic anhydride and the like. Preferred copolymerizable monomers are acrylic monomers such as acrylonitrile and methyl methacrylate. The amounts of vinyl aromatic monomer and acrylic acid monomer used to prepare the copolymer vary with respect to the physical and mechanical properties desired in the vinyl aromatic copolymer reinforced with the final rubber. The amount of acrylic monomer is generally from 5 to 45% by weight, preferably from 15 to 35% by weight, and correspondingly the amount of vinyl aromatic monomer is from 95 to 55% by weight, preferably from 85 to 65% by weight, based on the total weight of the vinyl aromatic monomer-acrylic monomer copolymer. The amount of diene rubber (i), (ii), (iii) or (iv) in the rubber-reinforced (co) polymer is generally from 4 to 30% by weight, preferably from 6 to 25% by weight, relative to the weight of the (co) polymer.

The rubber-reinforced (co) polymer targets of the present invention may be prepared by any conventional technique for preparing crosslinked high impact copolymers, such as bulk polymerization, solution, emulsion, and bulk suspension polymerization. The samples targeted from the (co) polymers of the present invention have a gloss at 60 ° higher than 85.

Some illustrative examples are provided for a better understanding of the present invention and its embodiments, which should in no way be considered to be of a limiting nature.

Characterization of the synthetic Polymer

1．Measurement of viscosity in styrene solution

The process involves preparing a 5% by weight solution of polybutadiene in styrene and subsequently measuring the viscosity at 25 ℃ using a Cannon Fenske capillary whose dimensions must be chosen so as to avoid elution times through the capillary which are neither too short nor too long. In the case of the polymers tested, model 300, which is effective in the range of 50-250 cP, was used.

2．Measurement of the average molecular weight of SAN substrates

The measurement of the average molecular weight of the SAN matrix was carried out on a chromatographic apparatus consisting of: degasser system, pump, syringe: WATERS Alliance2695, a set of 5 micron Phenogel columns (300 × 7.6 mm), porosity 106, 105, 104, 103 angstroms, WATERS410 differential refractive index detector, UV WATERS2487 detector, chromatography software: millenium32 version 3.2 (Waters).

3．Morphological measurement of rubber phase dispersed in ABS

The size and morphology of the rubber phase dispersed in the SAN matrix was measured by T.E.M. (transmission electron microscopy), F.Lenz, A.Wiss-Mikrroscopie 63,1956, page 56. The morphology of the rubber particles was determined by visual observation of the morphology and the various structures were characterized according to the classifications described in "Teilchenbildung bei der Herstellung von Kautschukmodifiertem Polystyrol" of Adolf Echte58/89(1977), pp.175-198 and EP716,664. To calculate the statistical parameter mean volume diameter DV of the particles, the following formula is used:

wherein D_iDenotes the diameter of the ith particle, and for the calculation of the "core-shell" type or with a "hybrid" structure (labyrinth)Or brain) using the logistic method described in c.maestrini et al, Journal of Material Science, vol.27,1992, page 5994. T.e.m. analysis was performed on a transmission electron microscope Philips CM 120.

4．Other characterizations

Concentration of residual styrene monomer and acrylonitrile and other volatile organic substances was measured by gas chromatography;

the concentration of polybutadiene in ABS was measured by iodine titration according to the method Wijs, Berichte,1898, vol.31, page 750;

gel phase content (after thermal crosslinking of the rubber) and swelling index (without thermal crosslinking of the rubber) were measured by means of the Ruffing test described in US4,214,056;

melt Flow Index (MFI) measured according to standard method ASTM D1238 at 200 ℃ under a weight of 5 kg;

notched Izod values (on injection-molded samples) were measured according to the standard method ISO 180/1A-ISO 179 (values in kJ/m)²Representation). Another parameter relating to the impact resistance of the material is represented by the falling ball, which is measured on two samples of different thickness (2 mm and 3 mm) according to standard method ISO 6603/2.

Tensile strength (yield strength, elongation at yield, stress at break, elongation at break, tensile modulus) and flexural strength properties (maximum stress, elastic modulus) were measured on injection molded samples according to standard methods ISO527, ISO178 and are expressed in MPa, except that elongation at yield and elongation at break are expressed in percent.

Gloss of the material was measured according to standard method ASTM D523 using a dr. lange photometer at two read angles (20 and 60 °). The measurements were performed on three-step samples obtained by injection molding, measuring a read-out area equal to 95mm x75mm x3 mm. The molding conditions for the test samples were as follows: melt temperature 220 ℃ and mold temperature 35 ℃.

Example 1

3.6kg of linear polybutadiene (i) having a solution viscosity of 44CPs at 5% in Styrene (SM), 20g of the antioxidant ANOX PP18 in 21.8kg of styrene monomer and 7.6kg of ethylbenzene were dissolved in a 60 l batch autoclave equipped with a temperature regulator and a stirring system and stirred for 5 hours at 85 ℃. 12.4g of initiator 1, 1-di (tert-butylperoxy) cyclohexane (Tx 22E 50) was then added.

After mixing with the acrylonitrile feed under heating (at a temperature of 60 ℃) in a solution/acrylonitrile weight ratio of 82.5/17.5, the solution thus obtained is fed into a first PFR reactor equipped with a stirrer and a temperature regulation system, in which the thermal profile of the reactor is increased from 112 ℃ to 120 ℃, in which the prepolymerization is carried out with grafting and reverse phase.

48g of transfer agent n-dodecylmercaptan (NDM) were added to the mixture leaving the first reactor and then transferred to a second PFR reactor, also equipped with a stirrer and a temperature regulation system, which increased the thermal profile of the reactor from 150 ℃ to 165 ℃.

The resulting mixture was fed to a devolatilizer operating under vacuum at a temperature of 235 ℃ to crosslink the rubber and remove unreacted monomer and solvent from the polymer. The molten polymer thus obtained was pelletized to obtain a final product, the characteristics of which are shown in table 1.

Example 2

3.6kg of a partially radial polybutadiene (ii) (10% by weight branched end group content) having a solution viscosity of 45CPs at 5% in Styrene (SM), 20g of the antioxidant ANOX PP18 in 21.8kg of styrene monomer and 7.6kg of ethylbenzene were dissolved in a 60 l batch autoclave equipped with a temperature regulator and a stirring system and stirred for 5 hours at 85 ℃. 12.4g of initiator 1, 1-di (tert-butylperoxy) cyclohexane (Tx 22E 50) was then added.

After mixing with the acrylonitrile feed under heating (at a temperature of 60 ℃) in a solution/acrylonitrile weight ratio of 82.5/17.5, the solution thus obtained is fed into a first PFR reactor equipped with a stirrer and a temperature regulation system, in which the thermal profile of the reactor is increased from 112 ℃ to 120 ℃, in which the prepolymerization is carried out with grafting and reverse phase.

48g of transfer agent n-dodecylmercaptan (NDM) were added to the mixture leaving the first reactor and then transferred to a second PFR reactor, also equipped with a stirrer and a temperature regulation system, which increased the thermal profile of the reactor from 150 ℃ to 165 ℃.

The resulting mixture was fed to a devolatilizer operating under vacuum at a temperature of 235 ℃ to crosslink the rubber and remove unreacted monomer and solvent from the polymer. The molten polymer thus obtained was pelletized to obtain a final product, the characteristics of which are shown in table 1.

Example 3

3.6kg of a three-armed polybutadiene (iii) with a solution viscosity of 42CPs at 5% in Styrene (SM), 20g of the antioxidant ANOX PP18 in 21.8kg of styrene monomer and 7.6kg of ethylbenzene were dissolved in a 60 l batch autoclave equipped with a temperature regulator and a stirring system and stirred for 5 hours at 85 ℃. 12.4g of initiator 1, 1-di (tert-butylperoxy) cyclohexane (Tx 22E 50) was then added.

After mixing with the acrylonitrile feed under heating (at a temperature of 60 ℃) in a solution/acrylonitrile weight ratio of 82.5/17.5, the solution thus obtained is fed into a first PFR reactor equipped with a stirrer and a temperature regulation system, in which the thermal profile of the reactor is increased from 112 ℃ to 120 ℃, in which the prepolymerization is carried out with grafting and reverse phase.

48g of transfer agent n-dodecylmercaptan (NDM) were added to the mixture leaving the first reactor and then transferred to a second PFR reactor, also equipped with a stirrer and a temperature regulation system, which increased the thermal profile of the reactor from 150 ℃ to 165 ℃.

The resulting mixture was fed to a devolatilizer operating under vacuum at a temperature of 235 ℃ to crosslink the rubber and remove unreacted monomer and solvent from the polymer. The molten polymer thus obtained was pelletized to obtain a final product, the characteristics of which are shown in table 1.

Example 4

3.4kg of linear polybutadiene (i) with a solution viscosity of 44CPs at 5% in Styrene (SM), 0.2kg of radial polybutadiene with a solution viscosity of 209CPs at 5% in Styrene (SM) -forming a mixture (iv) with a solution viscosity of 59CPs at 5% in Styrene (SM), 20g of the antioxidant ANOX PP18 in 21.8kg of styrene monomer and 7.6kg of ethylbenzene were dissolved in a 60 litre batch autoclave equipped with a temperature regulator and a stirring system and stirred for 5 hours at 85 ℃. 12.4g of initiator 1, 1-di (tert-butylperoxy) cyclohexane (Tx 22E 50) was then added.

After mixing with the acrylonitrile feed under heating (at a temperature of 60 ℃) in a solution/acrylonitrile weight ratio of 82.5/17.5, the solution thus obtained is fed into a first PFR reactor equipped with a stirrer and a temperature regulation system, in which the thermal profile of the reactor is increased from 112 ℃ to 120 ℃, in which the prepolymerization is carried out with grafting and reverse phase.

48g of transfer agent n-dodecylmercaptan (NDM) were added to the mixture leaving the first reactor and then transferred to a second PFR reactor, also equipped with a stirrer and a temperature regulation system, which increased the thermal profile of the reactor from 150 ℃ to 165 ℃.

The resulting mixture was fed to a devolatilizer operating under vacuum at a temperature of 235 ℃ to crosslink the rubber and remove unreacted monomer and solvent from the polymer. The molten polymer thus obtained was pelletized to obtain a final product, the characteristics of which are shown in table 1.

Example 5

3.2kg of linear polybutadiene (i) with a solution viscosity of 44CPs at 5% in Styrene (SM), 0.4kg of radial polybutadiene with a solution viscosity of 209CPs at 5% in Styrene (SM) -forming a mixture (iv) with a solution viscosity of 65CPs at 5% in Styrene (SM), 20g of the antioxidant ANOX PP18 in 21.8kg of styrene monomer and 7.6kg of ethylbenzene were dissolved in a 60 litre batch autoclave equipped with a temperature regulator and a stirring system and stirred for 5 hours at 85 ℃. 12.4g of initiator 1, 1-di (tert-butylperoxy) cyclohexane (Tx 22E 50) was then added.

After mixing with the acrylonitrile feed under heating (at a temperature of 60 ℃) in a solution/acrylonitrile weight ratio of 82.5/17.5, the solution thus obtained is fed into a first PFR reactor equipped with a stirrer and a temperature regulation system, in which the thermal profile of the reactor is increased from 112 ℃ to 120 ℃, in which the prepolymerization is carried out with grafting and reverse phase.

48g of transfer agent n-dodecylmercaptan (NDM) were added to the mixture leaving the first reactor and then transferred to a second PFR reactor, also equipped with a stirrer and a temperature regulation system, which increased the thermal profile of the reactor from 150 ℃ to 165 ℃.

The resulting mixture was fed to a devolatilizer operating under vacuum at a temperature of 235 ℃ to crosslink the rubber and remove unreacted monomer and solvent from the polymer. The molten polymer thus obtained was pelletized to obtain a final product, the characteristics of which are shown in table 1.

Reference example 6

3.6kg of polybutadiene SOL B183 (modified polybutadiene containing 10% by weight of styrene, produced by Polimeri Europa) (5% solution viscosity in Styrene (SM) ═ 30 CPs), 20g of antioxidant ANOX PP18 in 21.8kg of styrene monomer and 7.6kg of ethylbenzene were dissolved in a 60 l batch autoclave equipped with a temperature regulator and a stirring system and stirred at 85 ℃ for 5 hours. 12.4g of initiator 1, 1-di (tert-butylperoxy) cyclohexane (Tx 22E 50) was then added.

After mixing with the acrylonitrile feed under heating (at a temperature of 60 ℃) in a solution/acrylonitrile weight ratio of 82.5/17.5, the solution thus obtained is fed into a first PFR reactor equipped with a stirrer and a temperature regulation system, in which the thermal profile of the reactor is increased from 112 ℃ to 120 ℃, in which the prepolymerization is carried out with grafting and reverse phase.

48g of transfer agent n-dodecylmercaptan (NDM) were added to the mixture leaving the first reactor and then transferred to a second PFR reactor, also equipped with a stirrer and a temperature regulation system, which increased the thermal profile of the reactor from 150 ℃ to 165 ℃.

The resulting mixture was fed to a devolatilizer operating under vacuum at a temperature of 235 ℃ to crosslink the rubber and remove unreacted monomer and solvent from the polymer. The molten polymer thus obtained was pelletized to obtain a final product, the characteristics of which are shown in table 1.

Example 7 (comparative)

3.6kg of polybutadiene INTENE P30 (four-armed star polybutadiene, produced by Polimeri Europa) (5% solution viscosity in Styrene (SM) ═ 45 CPs), 20g of the antioxidant ANOX PP18 in 21.8kg of styrene monomer and 7.6kg of ethylbenzene were dissolved in a 60 liter batch autoclave equipped with a temperature regulator and a stirring system and stirred for 5 hours at 85 ℃. 12.4g of initiator 1, 1-di (tert-butylperoxy) cyclohexane (Tx 22E 50) was then added.

After mixing with the acrylonitrile feed under heating (at a temperature of 60 ℃) in a solution/acrylonitrile weight ratio of 82.5/17.5, the solution thus obtained is fed into a first PFR reactor equipped with a stirrer and a temperature regulation system, in which the thermal profile of the reactor is increased from 112 ℃ to 120 ℃, in which the prepolymerization is carried out with grafting and reverse phase.

48g of transfer agent n-dodecylmercaptan (NDM) were added to the mixture leaving the first reactor and then transferred to a second PFR reactor, also equipped with a stirrer and a temperature regulation system, which increased the thermal profile of the reactor from 150 ℃ to 165 ℃.

The resulting mixture was fed to a devolatilizer operating under vacuum at a temperature of 235 ℃ to crosslink the rubber and remove unreacted monomer and solvent from the polymer. The molten polymer thus obtained was pelletized to obtain a final product, the characteristics of which are shown in table 1.

Example 8 (comparative)

3.6kg of a partially radial polybutadiene (ii) (25% by weight branched end group content) having a solution viscosity of 65CPs at 5% in Styrene (SM), 20g of the antioxidant ANOX PP18 in 21.8kg of styrene monomer and 7.6kg of ethylbenzene were dissolved in a 60 l batch autoclave equipped with a temperature regulator and a stirring system and stirred for 5 hours at 85 ℃. 12.4g of initiator 1, 1-di (tert-butylperoxy) cyclohexane (Tx 22E 50) was then added.

After mixing with the acrylonitrile feed under heating (at a temperature of 60 ℃) in a solution/acrylonitrile weight ratio of 82.5/17.5, the solution thus obtained is fed into a first PFR reactor equipped with a stirrer and a temperature regulation system, in which the thermal profile of the reactor is increased from 112 ℃ to 120 ℃, in which the prepolymerization is carried out with grafting and reverse phase.

48g of transfer agent n-dodecylmercaptan (NDM) were added to the mixture leaving the first reactor and then transferred to a second PFR reactor, also equipped with a stirrer and a temperature regulation system, which increased the thermal profile of the reactor from 150 ℃ to 165 ℃.

The resulting mixture was fed to a devolatilizer operating under vacuum at a temperature of 235 ℃ to crosslink the rubber and remove unreacted monomer and solvent from the polymer. The molten polymer thus obtained was pelletized to obtain a final product, the characteristics of which are shown in table 1.

Example 9 (comparative)

2.7kg of linear polybutadiene (i) with a solution viscosity of 44CPs at 5% in Styrene (SM), 0.9kg of radial polybutadiene with a solution viscosity of 209CPs at 5% in Styrene (SM) -forming a mixture (IV) with a solution viscosity of 85CPs at 5% in Styrene (SM), 20g of the antioxidant ANOX PP18 in 21.8kg of styrene monomer and 7.6kg of ethylbenzene were dissolved in a 60 liter batch autoclave equipped with a temperature regulator and a stirring system and stirred for 5 hours at 85 ℃. 12.4g of initiator 1, 1-di (tert-butylperoxy) cyclohexane (Tx 22E 50) was then added.

After mixing with the acrylonitrile feed under heating (at a temperature of 60 ℃) in a solution/acrylonitrile weight ratio of 82.5/17.5, the solution thus obtained is fed into a first PFR reactor equipped with a stirrer and a temperature regulation system, in which the thermal profile of the reactor is increased from 112 ℃ to 120 ℃, in which the prepolymerization is carried out with grafting and reverse phase.

48g of transfer agent n-dodecylmercaptan (NDM) were added to the mixture leaving the first reactor and then transferred to a second PFR reactor, also equipped with a stirrer and a temperature regulation system, which increased the thermal profile of the reactor from 150 ℃ to 165 ℃.

The resulting mixture was fed to a devolatilizer operating under vacuum at a temperature of 235 ℃ to crosslink the rubber and remove unreacted monomer and solvent from the polymer. The molten polymer thus obtained was pelletized to obtain a final product, the characteristics of which are shown in table 1.

Example 10 (comparative)

3.6kg of polybutadiene INTENE40 (linear polybutadiene, produced by Polimeri Europa) (5% solution viscosity 95CPs in Styrene (SM)), 20g of antioxidant ANOX PP18 in 21.8kg of styrene monomer and 7.6kg of ethylbenzene were dissolved in a 60 liter batch autoclave equipped with a temperature regulator and a stirring system and stirred for 5 hours at 85 ℃. 12.4g of initiator 1, 1-di (tert-butylperoxy) cyclohexane (Tx 22E 50) was then added.

After mixing with the acrylonitrile feed under heating (at a temperature of 60 ℃) in a solution/acrylonitrile weight ratio of 82.5/17.5, the solution thus obtained is fed into a first PFR reactor equipped with a stirrer and a temperature regulation system, in which the thermal profile of the reactor is increased from 112 ℃ to 120 ℃, in which the prepolymerization is carried out with grafting and reverse phase.

48g of transfer agent n-dodecylmercaptan (NDM) were added to the mixture leaving the first reactor and then transferred to a second PFR reactor, also equipped with a stirrer and a temperature regulation system, which increased the thermal profile of the reactor from 150 ℃ to 165 ℃.

The resulting mixture was fed to a devolatilizer operating under vacuum at a temperature of 235 ℃ to crosslink the rubber and remove unreacted monomer and solvent from the polymer. The molten polymer thus obtained was pelletized to obtain a final product, the characteristics of which are shown in table 1.

TABLE 1

Claims (9)

1. A rubber-reinforced vinyl aromatic polymer or copolymer comprising a polymer matrix and a rubber phase of a diene rubber dispersed and/or grafted in the polymer matrix, wherein the rubber phase is selected from at least one of:

(i) a linear diene rubber consisting of polybutadiene having a solution viscosity of 40 to 70cPs, a 1,2 vinyl content of 5 to 35 wt% and a 1, 4-cis content of 20 to 85 wt%, measured as a 5 wt% solution in styrene at 25 ℃;

(ii) a partial radial diene rubber having a solution viscosity lower than 70cPs, wherein at most 15% by weight of the polymer chain ends have an amount of tetrafunctional coupling agent to produce a radial terminal structure of linear diene rubber chains;

(iii) a three-branched diene rubber having a solution viscosity of less than 70cPs, which is a linear diene rubber consisting of polybutadiene coupled with a trifunctional agent, said polybutadiene having a solution viscosity of 40 to 70cPs, a 1,2 vinyl content of 5 to 35% by weight, and a 1, 4-cis content of 20 to 85% by weight, measured as a 5% by weight solution in styrene at 25 ℃;

(iv) mixtures of linear diene rubber (i) and radial diene rubber (v) having a maximum ratio of (i)/(v) to each other of 99.5/0.5 to 85/15, with a solution viscosity lower than 70 cPs.

2. The vinyl aromatic polymer or copolymer according to claim 1, wherein the diene rubber in the radial diene rubber (ii) or in the radial diene rubber (V) consists of a polymer of a 1, 3-conjugated diene containing from 4 to 6 carbon atoms.

3. A vinyl aromatic polymer or copolymer according to claim 1, wherein the diene rubber is a polybutadiene having the following characteristics:

a solution viscosity of 40 to 60cPs, measured at 25 ℃ in a 5% by weight solution in styrene;

1,2 vinyl content of 7-14 wt%;

a 1, 4-cis content of 25-45 wt.%; and

(iv) the molecular structures described in (i), (ii), (iii) or (iv).

4. A vinyl aromatic polymer or copolymer according to claim 1 wherein from 1 to 12% by weight of the polymer chain ends in (ii) have an amount of tetrafunctional coupling agent to produce a radial terminal structure of linear diene rubber chains.

5. Vinyl aromatic polymer or copolymer according to any of the preceding claims comprising an acrylic comonomer in an amount of from 5 to 45 wt%.

6. The vinyl aromatic polymer or copolymer according to any of the preceding claims 1 to 4 wherein the amount of diene rubber (i), (ii), (iii) or (iv) is from 4 to 30% by weight.

7. The vinyl aromatic polymer or copolymer according to claim 5, wherein the amount of diene rubber (i), (ii), (iii) or (iv) is from 4 to 30% by weight.

8. Process for the preparation of rubber-reinforced vinylaromatic polymers or copolymers according to any of claims 1 to 7, comprising polymerizing at least one vinylaromatic monomer by means of bulk polymerization, solution, emulsion and bulk suspension in the presence of at least one rubber selected from the groups (i) to (iv).

9. Use of a rubber-reinforced vinyl aromatic polymer or copolymer according to any of claims 1 to 7 for the preparation of shaped bodies having a gloss measured at 60 ° according to the standard method ASTM D523 of higher than 85.