MXPA00008477A - Polymer mixtures comprised of styrene polymers - Google Patents

Abstract

The invention relates to polymer mixtures containing P1) 1-85 wt.%of a rubber-elastic block copolymer which is constructed out of rigid blocks S comprised of vinyl-aromatic monomers and statistical non-rigid blocks B/S comprised of dienes and vinyl-aromatic monomers, and which at least contains the block structure S-B/S-S. The diene content is less than 50 wt.%with regard to the total block copolymers, and the portion of the soft phase formed from the blocks B/S amounts to at least 60 wt.%also with regard to the total block copolymers;P2) 5-89 wt.%of a block copolymer which differs from P1) and which is comprised of vinyl-aromatic monomers and dienes;P3) 10-94 wt.%glass-clear or impact-resistant polystyrenes or mixtures thereof, and;P4) 0-84 wt.%of additional additives, whereby the sum of the components P1) to P4) is equal to 100%.

Description

POLYMER MIXTURES PREPARED FROM STYRENE POLYMERS The present invention relates to polymer blends consisting of: Pl) from 1 to 85% by weight of a block elastomeric copolymer that has been made up of hard blocks S made of vinylaromatic monomers and random soft blocks B / S made from dienes and vinylaromatic monomers, and which contains at least the structure of the SB / SS block, where the content of dienes is less than 50% by weight and the proportion of the soft phase formed of the B / S blocks is at least 60% by weight, based in each case on the entire block copolymer, P2) from 5 to 85% by weight of a block copolymer different from Pl) and prepared from vinylaromatic monomers and from diene. P3) from 10 to 94% by weight of transparent polystyrene such as glass or impact resistant or mixtures thereof, and P4) from 0 to 84% by weight of other additives, where the total of the components Pl) to P4) It is 100%. The invention also relates to the use of polymer blends to produce fibers, films or castings, and also to the resulting fibers, films and molded parts. WO 96/20248 discloses mixtures of shock resistant elastomers and thermoplastics, which can be processed like thermoplastics. The elastomers used can be block copolymers of styrene-butadiene with a flexible soft block B / S with a random sequence of styrene-butadiene and hard blocks S made from styrene. These block copolymers are used in thermoplastics for the modification against shocks. The aforementioned thermoplastics are, among others, pllstyrene or transparent polystyrene-butadiene block copolymers such as glass or impact resistant. During the processing, these present better mechanical properties and low shrinkage of the castings. The use of these polymer blends to produce transparent, flexible films is described in WO 96/23823. The stiffness or tenacity of the thermoplastics can be increased by adding butadiene rubbers or block copolymers of styrene-butadiene. However, with this addition there is usually an associated reduction in stiffness. In addition, high proportions of butadiene in the polymers used for impact resistance can reduce thermal resistance and weather resistance. High proportions of rubbers or block copolymers also make the corresponding thermoplastic molding compositions more expensive. It is an object of the present invention to provide polymer blends that are easy to process and have high ultimate tensile strength together with rigidity which can be adjusted over a wide range. Compared to traditional polystyrene blends, polymer blends must have the same elongation at break with a very low proportion of polymers containing butadiene. We have found that this goal is achieved by means of the polymer blends mentioned at the beginning. The novel polymer blends consist of, as component Pl), from 1 to 85% by weight, preferably from 2 to 62% by weight, particularly preferably from 5 to 35% by weight of a block elastomeric copolymer which has been consisting of hard blocks S prepared from vinylaromatic monomers and random B / S soft blocks made from dienes and vinylaromatic monomers, and containing at least the block structure SB / SS, where the content of dienes is less than 50% by weight, and the proportion of the soft phase formed of the B / S blocks is at least 60% by weight, based in each case on the entire block copolymer. A feature of the block copolymers Pl) is that a B / S block of randomized and elaborate structure of diene units and vinylaromatic units occurs as the soft phase instead of a pure polydiene block in a vinylaromatic-diene block copolymer elaborated of blocks that form the hard (S block type) and soft phases. In this case the structure along the chain can, in a statistical average, be homogeneous or non-homogeneous. A block elastomeric copolymer of this type according to the invention is obtained within the aforementioned parameters by forming the soft phase of a random copolymer of a vinylaromatic compound with a diene. The random copolymers of vinylaromatic compounds and dienes are obtained by polymerization in the presence of a polar co-solvent or a potassium salt. The random incorporation of the vinylaromatic compound into the soft block of the block copolymer and the use of Lewis bases during the polymerization modify the glass transition temperature (Tg). The glass transition temperature of the soft block B / S is preferably from -50 to +25 ° C, preferably from -50 to + 5 ° C, particularly preferably from -50 to -15 ° C. The glass transition temperature of the hard block S is preferably above 25 ° C, particularly preferably above 50 ° C.

The molar mass of a S block is preferably from 1000 to 200,000 g / mol, in particular from 5,000 to 50,000 g / mol. It is very particularly preferable that the molar mass of an S block is from 10,000 to 20,000 g / mol. The S blocks within a molecule can have different molar masses. The molar mass of the B / S block is usually from 2000 to 250,000 g / mol and preferably from 20,000 to 150,000 g / mol. The B-S block, like the S block, can adopt different molecular weights within a molecule. The preferred polymer structures are S-B / S-S, X - [- B / S-S] 2 and Y - [- B / S-S] 2. X is the radical of a bifunctional coupling agent and Y is the radical of a bifunctional initiator. The random block B / S can again be subdivided into blocks (B / S) - (B / S) 2 ~ (B3 / S) 3 -... The random block is preferably composed from 2 to 15 sub - random blocks, particularly preferably from 3 to 10 sub-blocks. The division of the random B / S block into multiple sub-blocks (B / S) n has the important advantage that the total B / S block behaves like an almost perfect random polymer even if there is a gradient in its constitution within a sub -block (B / S) n > -as it is difficult to avoid anionic polymerization under industrial conditions (see below). Therefore, it is preferable to use less than the theoretical amount of the Lewis base. This increases the proportion of 1,4-diene links, reduces the glass transition temperature Tg and reduces the tendency of the polymer to crosslink. Preference is given to a block copolymer of one of the formulas S-B / S-, where S is a vinylaromatic block, and B / S is the elaborate soft phase of a randomly constituted block of diene units and vinylaroid units. The soft phase can be "subdivided into blocks (B / S)? ~ (B / S) 2r where indexes 1 and 2 represent different structures "in the sense that the vinylaromatic / diene ratio is different in the individual B / S blocks or changes continuously within a block within the limits (B / S). S) i (B / S), where the glass transition temperature Tg of each sub-block is less than 25 ° C. Particular preference is given to a soft block B / S that has been subdivided into more than one block (B / S) n of identical constitution Preference is also given to a block copolymer having, in each molecule, more than a B / S block and / or S with different molar mass.

Preferred vinylaromatic compounds for the purposes of the invention are styrene and also α-methylstyrene and vinyltoluene, and also mixtures of these compounds. The preferred dienes are butadiene and isoprene, and also piperylene, 1-phenylbutadiene and mixtures of these compounds. A particularly preferred monomer combination is butadiene and styrene. All weight and volume data in the following are based on this combination. If the technical equivalents of styrene and butadiene are used, the data must be recalculated as appropriate. The soft block B / S is preferably composed of from 75 to 30% by weight of styrene and from 25 to 70% by weight of butadiene. A particularly preferred soft block B / S has a butadiene ratio from 35 to 70% and a styrene ratio from 65 to 30%. In the case of the combination of styrene / butadiene monomers, the proportion by weight of the diene in the complete block copolymer is from 15 to 50% by weight, and that of the vinyl aromatic component is from 85 to 50% by weight. Particular preference is given to block copolymers of butadiene-styrene with a monomer formed from 25 to 40% by weight of diane and from 75 to 60% by weight of vinylaromatic compounds. The block copolymers Pl) can be obtained by anionic polymerization in a non-polar solvent with the addition of a polar co-solvent or a potassium salt, as described, for example, in WO 96/20248 or WO 97/4007. According to the invention, the weight ratio of the soft phase created from diene sequences and vinylaromatic sequences is from 60 to 95% by weight, preferably from 60 to 80% by weight and, particularly preferably from 65 to 75% by weight. The blocks S produced from the vinylaromatic monomers form the hard phase, the proportion by weight of which is in correspondence 5 to 40% by weight, preferably from 20 to 40% by weight and, particularly preferably from 25 to 35% by weight. weight. Block copolymers have a property profile very similar to plasticized PVC, but can be prepared completely without low molecular weight plasticizers that can migrate. These have high permeability to oxygen P0 and water vapor permeability Pw greater than 2000 [cm 3 - 100 μ / m2 - d 'bar] and greater than 10 [g 100 2 μ / m • d * bar] respectively, where PD is the amount of 3 oxygen in cm, and Pw is the amount of water vapor in grams that permeates through 1 m of the film with a normal thickness of 100 μ during a day and 1 bar of partial pressure difference. The novel polymer mixtures contain, as component P2) from 5 to 89% by weight, preferably from 18 to 78% by weight, particularly preferably from 25 to 55% by weight of a block copolymer composed of vihilaromatic monomers and of diene and different from Pl). The block copolymer P2) differs from Pl) if it has a breaking elongation greater than 100% and a modulus of elasticity greater than 100 MPa. The preferred compounds P2) are rigid and rigid styrene-butadiene block copolymers with a butadiene content in the range from 5 to 40% by weight, in particular from 10 to 30% by weight, of butadiene and from 60 to 95% by weight, in particular from 70 to 90% by weight of styrene, based on the entire block copolymer P2). A particularly preferred block copolymer P2) is a branched, non-elastomeric star block copolymer. Another preferred component P2) is a block copolymer with terminal hard S blocks composed of vinylaromatic monomers. The molecular weight of the block copolymers P2) is, in general, in the range from 100,000 to 1,000,000, and preferably from 150,000 to 500,000. These can be linear or branched and are obtained by the usual methods of anionic polymerization in sequence. The preparation of the suitable branched block copolymers as the component P2) is described, for example, in EP-A-0 046 862. Star-block or linear styrene-butadiene block copolymers are commercially available under the names Styrolux® (BASF), K-Resin® (Phillips Petroleum) and Finaclear® (Fina) are also examples of suitable polymers. The novel polymer blends can contain, as component P3), from 10 to 94% by weight, preferably from 20 to 80% by weight, particularly preferably from 40 to 70% by weight of a transparent polystyrene such as glass or resistant to shock, or mixtures thereof. The normal polystyrenes and shock-resistant polystyrenes according to the invention, their preparation and structure and properties, have been described in detail in the literature (A. Echte, F. Haaf, J. Hambrecht in Angew. Chem. (Int. Ed. Engl.) 20, (1981) 344-361, and also Kunststoffhandbuch, vol.4, Polytyrol, Carl Hanser Verlag (1996)). The shock-resistant polystyrenes used in addition may also have been modified in their structure by the use of specific polybutadiene rubbers, for example, those having 1,4-cis and 1,4-trans ratios or 1,2 and 1,2 linkages. 1.4 different links of traditional rubbers.

It is also possible in place of polybutadiene rubber to use other diene rubbers or else elastomers such as ethylene-propylene-diene copolymer (EPDM rubbers) or also hydrogenated dienes. Conventional normal polystyrene is prepared by the process of anionic or free radical polymerization. The lack of homogeneity of the polymer, which can be affected by the polymerization process, is of secondary importance in this case. Preference is given to normal polystyrene and impact modified polystyrene having a toluene-soluble fraction of molar mass Mw from 50,000 to 500,000 g / mol, and which has also been modified, if desired, with additives such as oil mineral, stabilizers, antistatic, flame retardants or waxes. The novel polymer blends can contain, as component P4), from 0 to 84% by weight, preferably from 0 to 60% by weight, particularly preferably from 0 to 30% by weight of other additives. Novel polymer blends can contain, as component P4), other additives such as processing aids, stabilizers, oxidation inhibitors, agents to counteract the decomposition by heat and decomposition by ultraviolet light, lubricants, mold release agents, dyes such as dyes and pigments, fillers fibrous and powdery, fibrous and pulverulent reinforcing agents, nucleating agents, plasticizers, etc., generally in proportions not greater than 70% by weight, preferably not greater than 40% by weight. Examples of the oxidation inhibitors and thermal stabilizers are metal halides of group I of the Periodic Table, sodium, potassium and / or lithium, if desired in combination with copper (I) halides, for example. chlorides, bromides, and iodides, phenols with spherical hindrance, hydroquinones, different substituted representatives of these groups and mixtures thereof, in concentrations of up to 1% by weight, based on the weight of the thermoplastic composition for molding. The UV light stabilizers which can be mentioned, and which are generally used in amounts of not more than 2% by weight, based on the molding composition, are the different resorsinoles, salicylates, benzotriazoles and substituted benzonfenones. It is also possible to use organic dyes such as nigrosine, pigments such as titanium dioxide, cadmium sulfide, cadmium phthalocyanine selenide, ultramarine blue and carbon black as colorants, and also fibrous and powdery fillers and fibrous and powdery reinforcing agents. Examples of the latter are carbon fibers, glass fibers, amorphous silica, asbestos, calcium silicate (wollastonite), aluminum silicate, magnesium carbonate, kaolin, chalk, quartz powder, mica and feldspar. The proportion of these fillers and dyes is in general up to 50% by weight, preferably up to 35% by weight. Examples of the nucleating agents that can be used are: talc, calcium fluoride, sodium phenylphosphinate, alumina, silica and nylon 2.2. Examples of mold releasing agents and lubricants, which can generally be used in amounts not greater than 1% by weight, are long chain fatty acids, such as stearic acid or behenic acid, salts of these (eg, calcium stearate) or zinc stearate) or esters (e.g., stearyl stearate or pentaerythritol tetrastearate) and also amide derivatives (e.g., ethylenebistearyl ida). To improve the processing of the film, it is possible to add to the novel molding compositions no more than 0.1% by weight of antiblocking agents based on minerals. Examples of these are amorphous or crystalline silica, calcium carbonate and aluminum silicate. Examples of the plasticizers are dioctyl phthalate, dibenzyl phthalate, butylbenzyl phthalate, hydrocarbon oils, N-n-butylbenzenesulfonamide and o- and p-tolyethylsulfonamide.

In order to further improve the flame resistance, it is possible to add any of the known flame retardants for the respective thermoplastics, in particular red phosphorus and / or flame retardants based on phosphorus compounds. The novel molding compositions can be prepared by the processes known per se. In a preferred embodiment, the preparation is by the addition of a component Pi) and, if desired, P3) to the melt of component P2). For this purpose, extruders, for example, single-screw or double-screw extruders, or other conventional plasticizing apparatus such as Brabender mixers or Banbury mixers may be useful. The novel polymer blends have good mechanical properties (strength and stiffness) and good thermo resistance. Therefore, these are suitable for producing molded parts and semi-finished products of any kind, such as lamination history sheets, expansion bellows, flexible bellows, grilles, coatings, floor coverings, shoe soles, under rugs from wall to wall, artificial skin, blow molded parts, extruded profiles, injection molded parts, extruded tubes, and also three-dimensional blow molded parts. What is surprising, it has been found that the polymer blends composed of Pl) and P2) in any mixing ratio are transparent despite the presence of a three phase system. The elastic limit of these polymer mixtures increases linearly with the proportion of P2). This allows, for example, to adjust the hardness, rigidity and flexibility in films or other applications, such as injection molded parts. Despite their constitution, the polymer blends made of Pl), P2) and P3) can cover the range of properties from transparent polystyrene, shock resistant to thermoplastic elastomers (TPE). These are particularly suitable for transparent films. The novel polymer blends with modified polystyrene (HIPS) as component P3) have higher cracking resistance than shock-resistant polystyrene.

Examples Component Pl Component Pl was prepared according to DE-A 44 20 952 A stainless steel reactor, 50 liters, capable of being heated and cooled and adapted with a cross-rod stirrer was prepared by flooding it with nitrogen and heating up to below of the boiling point with a solution of sec-butyllithium and 1,1-diphenylethylene in cyclohexane (molar ratio: 1: 1) and drying. 22.8 1 of cyclohexane and 42 ml of sec-butyllithium as initiator were placed in the reactor with 65.8 ml of tretrahydrofuran and the amounts of styrene (S) and butadiene (B) shown in Table 1 below were added according to the program of the certain time cycle. The data provided are the duration t in minutes of the polymerization and the initial and final temperatures j and TF, respectively (in ° C), and it should be noted that the duration of the polymerization was always large compared to the duration of the monomer fed. The temperature of the reaction mixture was controlled by heating or cooling the jacket of the reactor. After the reaction was over (the consumption of the monomers), the ethanol was titrated until the mixture was colorless, and the mixture was acidified with a 1.5 fold excess of formic acid. Finally, 34 g of commercial stabilizer (2-tert-butyl-6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate (Irganox® 3052; Ciba-Geigy, Basel)) and 82 g of tris (nonylphenyl) phosphite were added.

The solution was treated in a ventilated extruder (with three domes, forward and backward degassing) at 200 ° C, and granulated. The granules were mixed in a fluid mixer with 10 g of bis stearylamide (Acrawax) as an external lubricant. The block copolymer had a melt volume velocity MFR (20 ° C / 5 kg) of 12 cm 3/10 min.

Table 1 The molar masses were determined by gel permeation chromatography with a polystyrene standard (Mp = maximum peak molar mass).

Component P2-1) Styrene-butadiene block copolymer with a melt volume velocity MFR (200 ° C / 5 kg) of 14 cm / 10 min and an elastic tensile modulus of 1300 MPa (Styrolux® 693 D BASF).

Component P2-2) Styrene-butadiene block copolymer with a melt volume velocity MFR (200 ° C / 5 kg) of 11 cm / 10 min and a tensile modulus of 1550 MPa (Styrolux® 684 D of BASF).

Component P3-1) Polystyrene standard with a melt volume rate MER (200 ° C / 5 kg) of 3 cm3 / 10 min and a modulus of tensile elasticity of 3300 MPa (polystyrene 158 K from BASF).

Component P3-2) Standard polystyrene with a melt volume velocity MFR (200 ° C / 5 kg) of 2.5 cm3 / 10 min and a modulus of tensile elasticity of 3300 MPa (polystyrene 165 H from BASF).

Component P3-3) Polystyrene with high impact resistance with a melt volume rate MFR (200 ° C / 5 kg) of 3 cm / 10 min and a tensile modulus of 1800 MPa (486 M polystyrene from BASF ).

Preparation of the molding compositions The components Pl) to P4), in the proportions by weight mentioned in Table 2, were melted in a double-screw extruder (ZSK 25 of Werner &Pfleiderer) at 200 ° C and a yield of 10 kg / h, homogenized and extruded in a water bath. The dried granules were then injection molded to obtain the samples for the standard tests. Tables 2 and 3 provide the properties of the polymer blends, measured in compression molded and injection molded test samples, respectively.

Film production: Novel films, and also films produced for comparative purposes, were produced in an extruder (Battenfeld: propeller diameter 45 mm, propeller length 25 D, melt temperature 214 ° C) by the process of roller with cooling with a roller temperature of 60 ° C. The films had a thickness of approximately 250μ. The compositions of the films and the results of the measurements are mentioned in Tables 4 and 5.

Measurement methods: MFR melt volume rate (200 ° C / 5 kg) was measured in accordance with ISO 1133. The samples for the mechanical tests were injection molded at 220 ° C, the melt temperature and 45 ° C mold temperature. The modulus of elasticity, the elastic limit, the resistance to breakage, deformation and elongation to breakage were determined in the tensile test according to ISO 527 with samples for traction according to ISO 3167. The Charpy shock resistance was tested in accordance with ISO 179 / leU, and impact resistance with notch Charpy according to ISO 179 / leA in injection molded parts with dimensions of 80 x 10 x 4 mm. The brightness was determined in test samples molded by injection, flat 1.5 mm thick, with angles of incidence from 20 °, 65 ° and 85 °. 100 divisions of the scale (DS) in this case represent the total reflection in an interface. Values greater than 100 divisions of the scale indicate reflection on the upper and lower sides. The relative transparencies were determined against air in the injection molded parts with a thickness of 4 mm. The Vicat softening points VST / A and VST / B were determined in accordance with the DIN ISO 306 test specification. The falling weight test was performed in accordance with DIN 53 443. The polybutadiene fraction (Pbu) was determined by Wijs titling. The films 1 to 7 have good transparency. Films 5 to 7, which also contain small amounts of shock-resistant polystyrene, have very good stiffness with excellent strength.

Table 2: Compositions and properties of the polymer mixture (compression molded test samples) 15 Table 2 Continuation fifteen Table 2 (continued) fifteen Table 3: Properties of the polymer mixture (test samples molded by injection) JO fifteen ND: not determined F: fracture fifteen Table 4: Content and properties of the film Table 4 (continued) Table 5: Composition and properties of films 5 to 7

Claims (1)

1. REVINDICATIONS A polymer mixture containing: Pl) from 1 to 85% by weight of a block elastomeric copolymer which has been created from hard blocks S consisting of vinylaromatic monomers and random B / S soft blocks consisting of dienes and vinylaromatic monomers , and which contains at least the structure of the SB / SS block, where the content of dienes is less than 50% by weight and the proportion of the soft phase formed of the B / S blocks is at least 60% by weight, based on in each case in the complete block copolymer, P2) from 5 to 89% by weight of a block copolymer other than Pl) and vinylaromatic and diene monomer compounds. P3) from 10 to 94% by weight of transparent polystyrene such as glass or impact resistant or mixtures thereof, and P4) from 0 to 84% by weight of other additives. where the total of the components Pl) to P4) is 100%. The polymer blend as claimed in claim 1, which contains: from 2 to 62% by weight of Pl), from 18 to 78% by weight of P2), from 20 to 80% by weight of P3), and from 0 up to 60% by weight of P4). The polymer blend as claimed in claim 1, consists of: from 5 to 35% by weight of Pl), from 25 to 55% by weight of P2), from 40 to 70% by weight of P3), and from 0 up to 30% by weight of P4). The polymer blend as claimed in any of claims 1 to 3, wherein the block copolymer P2) used is a block copolymer with a breaking elongation greater than 100% and a mos of elasticity greater than 100 MPa. The polymer blend as claimed in any of claims 1 to 4, wherein the block copolymer P2) used is a branched, star-shaped, non-elastomeric block copolymer composed of: from 60 to 95% by weight of a vinylaromatic monomer and from 40 to 5% by weight of a conjugated diene. The polymer blend as claimed in any of claims 1 to 5, wherein the block copolymer P2) used is a block copolymer with terminal hard blocks S composed of vinylaromatic monomers. The use of the polymer blends as claimed in any of claims 1 to 6 to produce fibers, films or molded parts. A fiber, film or molded part that can be obtained from the polymer blends as claimed in any of claims 1 to 6.