DE19836621A1 - Polystyrene-based thermoplastic molding composition used for producing fibers, films and articles comprises an elastomeric particulate graft polymer - Google Patents

Abstract

Polystyrene-based thermoplastic molding composition comprises: (A) 30-99.9 wt.% syndiotactic vinyl aromatic polymer; (B) 0.1-70 wt.% elastomeric particulate graft polymer of D50 value 0.1-10 micro m; and (C) 0-69.9 wt.% elastomeric particulate styrene/diene block copolymer. An Independent claim is included for fibers, films and articles obtained from the above composition.

Description

The invention relates to thermoplastic molding compositions containing

• A) from 30 to 99.9 wt .-% of a vinyl aromatic polymer with syndiotactic structure
• B) 0.1 to 70 wt .-% of a rubber-elastic, teilchenfömigen graft
• C) 0 to 69.9 wt .-% of a rubber-elastic, divide-shaped Styrene / diene block copolymers whose diene content is complete or partially hydrogenated.

Furthermore, the invention relates to the use of the thermo plastic molding compounds for the production of fibers, films and Moldings, and the fibers, films and Moldings.

Syndiotactic polystyrene possesses due to its Crystallinity has a very high melting point of about 270 ° C, high Stiffness and tensile strength, dimensional stability, a low dielectric constant and high chemicals resistance. The mechanical property profile is itself at Maintain temperatures above the glass transition temperature. The production of syndiotactic polystyrene in the presence of metallocene catalyst systems is known and z. B. described in detail in EP-A 0 535 582.

Because of the brittleness of syndiotactic polystyrene is the Field of application severely limited.

There was therefore a desire for the brittleness of syndiotactic Polystyrene, hereinafter also referred to as SPS, reduce and at the same time to improve its impact resistance.

EP-A 755 972 describes SPS, which with a mixture of a Block copolymers of styrene and hydrogenated butadiene on the one hand and a core shell polymer having a butadiene polymer core on the other hand impact modified. Such modifiers are but not heat- or weather-resistant, have an un  sufficient impact resistance and are u. a. therefore not the optimal solution of the problem.

Object of the present invention, it was therefore a thermopla Static molding compound based on SPS produce the high impact toughness, high rigidity (modulus of elasticity) and good flowability (MVR, processability) combined and still witte is stable.

Accordingly, the initially defined thermoplastic form found masses.

Furthermore, the use of the thermoplastic molding compositions for the production of fibers, films and moldings found as well the fibers, films and moldings obtainable therefrom.

The novel thermoplastic molding compositions comprise as component A) from 30 to 99.9% by weight, preferably from 40 to 99% by weight, in particular from 50 to 95% by weight, of a vinylaromatic polymer having a syndiotactic structure. The term "syndiotactic structure" means here that the polymers are substantially syndiotactic, ie the syndiotactic fraction determined by ¹³ C NMR is greater than 50%, preferably greater than 60%, pentads.

Preferably, component A) is composed of compounds of general formula I.

in which the substituents have the following meanings:
R ^{1 is} hydrogen or C ₁ - to C ₄ -alkyl,
R ² to R ⁶ independently of one another are hydrogen, C ₁ - to C ₁₂ -alkyl, C ₆ - to C ₁₈ -aryl, halogen or where two adjacent radicals together have from 4 to 15 C-atoms having cyclic groups, for example C ₄ -C ₈ -cycloalkyl or fused ring systems.

Preference is given to using vinylaromatic compounds of the formula I in which
R ^{1 is} hydrogen.

Suitable substituents R ² to R ⁶ are, in particular, hydrogen, C ₁ - to C ₄ -alkyl, chlorine, phenyl, biphenyl, naphthalene or anthracene. Two adjacent radicals can also stand together for cyclic groups having from 4 to 12 carbon atoms, so that, for example, naphthalene derivatives or anthracene derivatives result as the compound of general formula (I).

Examples of such preferred compounds are:
Styrene, p-methylstyrene, p-chlorostyrene, 2,4-dimethylstyrene, 4-vinylbiphenyl, vinylnaphthalene or vinylanthracene.

It can also mixtures of various vinyl aromatic Compounds are used, but preferably only one vinyl aromatic compound used.

Particularly preferred vinyl aromatic compounds are styrene and p-methylstyrene.

As component A) also mixtures of different vinyl used aromatic polymers with syndiotactic structure However, only a vinyl aromatic polymer is preferred used, in particular syndiotactic polystyrene (SPS).

Vinyl aromatic polymers (A) with syndiotactic structure as methods for their preparation are known per se and For example, in EP-A 535 582 described. At the manufacturer The procedure is preferably such that compounds of the general formula I in the presence of a metallocene complex and a cocatalyst reacts. As metallocene complexes are in particular pentamethylcyclopentadienyl titanium trichloride, penta methylcyclopentadienyltitanium trimethyl and pentamethylcyclopenta dienyltitanium trimethylate used.

The vinylaromatic polymers having syndiotactic structure generally have a molecular weight M _w (weight average) of 5000 to 10 000 000, in particular from 10 000 to 2 000 000 g / mol. The molecular weight distributions M _w / M _n are generally in the range from 1.1 to 30, preferably from 1.4 to 10.

As vinylaromatic polymers with syndiotactic structure A) also come syntiotactic star polymers based on vinyl flavor tischer monomers in question. These star polymers are, for example example in the older German patent application 196 34 375.5-44, in particular on pages 2, line 21 to page 6, line 25, and described in the examples.

The graft polymers B), whose core polymers not by polymerization of butadiene monomer - except in small amounts as crosslinkers - but preferably by polymerization of α-β-unsaturated carboxylic acids, α-β-unsaturated carboxylic acid esters or α-β-unsaturated nitriles, such as Acrylic acid, methacrylic acid, acrylic acid esters, methacrylic acid esters, acrylonitrile, meth acrylonitrile or mixtures thereof, optionally also be set to set of crosslinkers, are preferably obtained as follows: The liquid monomer or liquid monomer mixture M _K , which polymerizes to the core polymer P _K. is to be mixed with water and a protective colloid. The polymerization initiator is either also added now or only after the dispersion of the monomer, or after the heating of the dispersion. From the heterogeneous mixture is prepared by intensive stirring at high speed, a dispersion of the smallest monomer droplets in water, for which Intensivmi shear of any type are suitable. The desired particle size within the range defined by definition can be determined, for example, by taking a light microscopic photograph and determining the number of particles having a specific diameter by counting.

Start the polymerizations by heating the dispersion. The reaction, which is now carried out with moderate stirring, in which the droplets are not further divided, is continued until the conversion based on M _{K is} more than 50%, preferably more than 85%.

If the polymerization of the grafted core is complete, the reaction with the monomers M _S , from which the corresponding shells S, consisting of the polymer P _s , are formed, is continued in a manner known per se. Suitable monomers M _s are styrene or its derivatives, acrylates, methacrylates, α-methylstyrene, acrylonitrile and methacrylonitrile. Preferably, 100% of the vinylaromatic monomers, preferably styrene or mixtures of more than 80 wt .-%, preferably 85 to 95 wt .-%, styrene and up to 20 wt .-%, preferably 5 to 15 wt .-% of acrylonitrile as monomers M _s. It is also possible to start the grafting process when the polymerization conversion of the monomer M _{K is} still incomplete and is above 50%, preferably above 85%. In this case, the shell and core form a more fluid transition, compared with the sharper demarcation of core and shell polymer in the case of the first complete conversion of the core monomers.

If the graft polymer has only one shell, which is generally sufficient, then this consists of the material P _s . In some cases, especially when the grafting nuclei are relatively small and if one wants to introduce a larger amount of the core polymer P _K in the particles, multi-shell graft polymers of the construction P _K -P _s -P _K -P _{s are} recommended, wherein the inner shells may also consist of other polymers P _X , to thereby modify the properties of the graft polymers and thereby improve.

The dispersion of the monomers M _{K is} usually carried out at a temperature of 0 to 100 ° C, preferably at room temperature and used per kilogram of monomers usually 0.4 to 10 kg of water.

The protection suitable for the stabilization of the dispersion Colloids are water-soluble polymers which are the monomer droplets and the polymer particles formed therefrom and on protect this way from coagulation.

Suitable protective colloids are cellulose derivatives such as carboxymethylcellulose and hydroxymethylcellulose, poly-N-vinylpyrrolidone don, polyvinyl alcohol and polyethylene oxide, anionic polymers such as polyacrylic acid and cationic such as poly-N-vinylimidazole. The amount of these protective colloids is preferably 0.1 to 5 wt .-%, based on the total mass of the monomers M _K. Low molecular weight surface-active compounds, for example those of the anionic and cationic soap types, are generally unsuitable for the preparation of the graft polymers according to the invention alone since they lead to polymer particles of smaller diameters, as obtained in the emulsion polymerization. However, the use of a mixture of protective colloid and soap may be advantageous to achieve a lower particle size than is usually possible with the use of protective colloids alone.

Suitable polymerization initiators are radical formers, ins particular ones which are appreciably soluble in the monomers and which preferably have a half life of 10 hours when the Temperature is between 25 and 150 ° C ("ten-hour half-value time at 25 to 150 ° C "). For example, per oxides such as lauroyl peroxide, peroxosulfates, t-butyl perpivalate and Azo compounds such as azodiisobutyronitrile. For the production of the Grafted core and the graft cups is the use of various  possible initiators. The amount of initiators is in the general 0.1 to 2.5 wt .-%, based on the amount of monomials ren.

Furthermore, the reaction mixture preferably contains buffer substances such as Na ₂ HPO ₄ / NaH ₂ PO ₄ or Na citrate / citric acid in order to establish a substantially constant pH. In the polymerization, in particular of the shell-forming monomers M _S , molecular weight regulators, such as ethylhexyl thioglycolate or t-dedecylmercaptan, are generally added as well.

In general, the polymerization of the monomers M _K P _K to the best of Henden core is 25 to 150 ° C, preferably 40 to 120 ° C. The grafting of the shells on the core is generally carried out at 25 to 150 ° C, preferably 50 to 120 ° C. The lower limits of these ranges correspond to the decomposition temperatures of the particular polymerization initiators used.

The graft polymers B) contain a phase having a glass temperature of less than 0 ° C, preferably less than -10 ° C, and in particular less than -20 ° C. As polymers having derar term glass temperatures are primarily those which contain from 50 to 100 wt .-% of (C ₂ -C ₃₆ alkyl) acrylates such as ethyl acrylate, n-propyl, iso-propyl acrylate preferably n-butyl acrylate and / or 2-ethylhexyl acrylate are constructed. In addition to these so-called "soft" monomers, up to 50% by weight of so-called "hard" monomers such as methyl acrylate, (C ₁ -C ₁₂ -alkyl) -methacrylates, styrene and α-methylstyrene, acrylonitrile are also suitable and methacrylic nitrile. These polymers usually form the core of the poly mers, but can also form a shell.

Such, usually core polymers are obtained with up to 10 wt .-%, preferably with about 0.1 to 10 wt .-% bifunctional ler or polyfunctional comonomers, eg. B. butadiene and iso prene, divinyl esters of dicarboxylic acids such as succinic acid and adipic acid, diallyl and Divinylethern bifunctional alcohols such as ethylene glycol and butane-1,4-diol, diesters of acrylic acid and methacrylic acid with said bifunctional Alko fetch, 1 4-divinylbenzene and triallyl cyanurate. Especially preferred are the acrylic acid esters of tricyclodecenyl alcohol (dihydrodicyclopentadienyl acrylate) of the formula I.

and the allyl esters of acrylic acid and methacrylic acid.

In the graft polymers B), the mass ratio of the sum of all shells to the core is about 0.05: 1 to 2.5: 1. The average diameter of the particles - which are preferably prepared by the method of microsuspension, as in DE 197 02 733.4, in particular described on page 9, line 25 to page 18, line 6 - is about 0.1 to about 10 microns, preferably 0.2 to 9 microns, more preferably 0.3 to 7 microns. The average diameter corresponds to the D ₅₀ value, according to which 50% by weight of all particles have a smaller diameter and 50% by weight have a larger diameter than the diameter corresponding to the D ₅₀ value. In order to characterize the particle size distribution, in particular its width, in addition to the D ₅₀ value, the D ₁₀ -as well as the D ₉₀ -value are often indicated. 10% by weight of all particles are smaller and 90% by weight larger than the D ₁₀ diameter. Analogously, 90% by weight of all particles have a smaller diameter and 10% by weight have a larger diameter than the one corresponding to the D ₉₀ value.

Component B) preferably has a shell that is integral with the base polymeric, ie the SPS (derivative) compatible or partially is compatible.

The amount of component B) in the molding compositions according to the invention is in the range of 0.1 to 70 wt .-%, preferably 1 to 60 Wt .-% and in particular 5 to 50 wt .-%, based on the mold Dimensions.

The rubber-elastic component C) of a styrene / diene block copolymer whose diene content completely or partially can be hydrogenated, for example, from EP-A 755 972 known and, for example, under the name Kraton® G 1651 from Shell Kaew Other examples include Cariflex® TR grades (Shell), Finaprene® types (Fina) and Europrene® types (Enichen).

The sum of component A), B) and C) is 100 wt .-%.

The thermoplastic molding compositions of the invention may optionally Additives or processing aids or mixtures thereof be added in conventional amounts.

These are, for example, nucleating agents such as salts of Carbon, organic sulfonic or phosphoric acids, preferred Sodium benzoate, aluminum tris (p-tert-butylbenzoate), aluminum trisbenzoate, aluminum tris (p-carboxymethylbenzoate) and aluminum triscaproat; Antioxidants like phenolic antioxidants,  Phosphites or phosphonites, especially trisnornylphenyl phosphite; Stabilizers such as hindered phenols and hydroquinones. Furthermore, lubricants and mold release agents, dyes, Pigments and plasticizers are used.

As flame retardants organophosphorus compounds, such as Phosphates or phosphine oxides are used.

Examples of phosphine oxides are triphenylphosphine oxide, tritolyl phosphine oxide, trisnonylphenylphosphine oxide, tricyclohexylphosphine oxide, tris (n-butyl) phosphine oxide, tris (n-hexyl) phosphine oxide, Tris (n-octyl) phosphine oxide, tris (cyanoethyl) phosphine oxide, Benzylbis (cyclohexyl) phosphine oxide, benzylbisphenylphosphine oxide, Phenylbis- (n-hexyl) phosphine oxide. Particularly preferably used be triphenylphosphine oxide, tricyclohexylphosphine oxide, Tris (n-octyl) phosphine oxide or tris (cyanoethyl) phosphine oxide.

The phosphates are especially alkyl- and aryl-substituted Phosphates into consideration. Examples are phenyl bisdodecyl phosphate, Phenylbisneopentyl phosphate, phenylethyl hydrogenphosphate, phenyl bis (3,5,5-trimethylhexyl phosphate), ethyldiphenyl phosphate, Bis (2-ethylhexyl) p-tolyl phosphate, tritolyl phosphate, trixylyl phosphate, trimesityl phosphate, bis (2-ethylhexyl) phenyl phosphate, Tris (nonylphenyl) phosphate, bis (dodecyl) p (tolyl) phosphate, Tricresyl phosphate, triphenyl phosphate, di-butylphenyl phosphate, p- Tolylbis (2,5,5-trimethylhexyl) phosphate, 2-ethylhexyldiphenyl phosphate. Particularly suitable are phosphorus compounds in which each R is an aryl radical. Especially suitable is Tri phenyl phosphate, trixylyl phosphate and trimesityl phosphate. Of other cyclic phosphates can also be used. Be Particularly suitable here is diphenylpentaerythritol diphosphate. Also preferred is resorcinol diphosphate.

In addition, mixtures of different phosphorus connections are used.

Furthermore, the inventive thermoplastic Molding materials fibrous or particulate fillers or their Containing mixtures.

These are for example carbon or glass fibers, glass mats, Glass silk rovings or glass beads and potassium titanate whisker or Aramid fibers, preferably glass fibers. Glass fibers can with a Simple and a bonding agent to be equipped. The Einar Processing of these fibers can be both in the form of short glass fibers  as well as in the form of endless strands (rovings). before ferred glass fibers contain an aminosilane size.

Furthermore, amorphous silica, magnesium carbonate, powdered quartz, mica, talc, feldspar, calcium silicates or phyllosilicates are used.

The thermoplastic Förmmassen invention can by Mixing of the individual components generally at temperatures of 270 to 330 ° C in conventional mixing equipment, such as kneaders, Banbu Ry mixers and single-screw extruder, but preferably with a twin-screw extruder are obtained. To one as possible To obtain homogeneous molding compound is an intensive mixing necessary. The mixing order of the components can be varied be, so two or possibly more components but all components can also be premixed be mixed together.

The thermoplastic molding compositions according to the invention can also with other polymers, such as atactic or isotactic homo- Polystyrene, styrene copolymers with, for example, acrylonitrile, Methacrylates and / or diphenylethylene as comonomers, or with Polyamides, polyesters or polyphenylene ethers or mixtures of the polymers, generally as described above be mixed.

The novel thermoplastic molding compositions are characterized high impact strength, high rigidity and good Flowability (processability). They are suitable for her Position of fibers, films or moldings.

Examples Production of PLC Production of syndiotactic polystyrene (SPS)

9.2 mol of styrene (1000 g) were introduced into a round bottom flask rendered inert with nitrogen, and the solution was heated to 60 ° C. and treated with 78.3 ml of methylaluminoxane (MAO) from Witco (1.53 M in toluene) and 20 ml of diisobuthyaluminum hydride DIBAH (1.0 M in cyclohexane) from the company Aldrich. Subsequently, the mixture was admixed with 91.2 mg of [C ₅ (CH ₃ ) ₅ ] TiMe ₃ . The internal temperature was adjusted to 60 ° C and allowed to polymerize for 2 h. After 2 h, the polymerization was stopped by addition of methanol. The resulting polymer was washed with methanol and dried at 50 ° C in a vacuum. The molecular weights and their distribution were determined by high temperature GPC with 1,2,4-trichlorobenzene as solvent at 135 ° C. The calibration was carried out with narrowly distributed polystyrene standards. The molecular weight was M _w = 322 100 with a distribution width of M _w / Mn = 2.1. The syndiotactic portion determined by ¹³ C NMR was <96%. The conversion was 84% based on the monomer used styrene.

Preparation of the graft rubbers

The following starting materials were used:
Styrene (St), acrylonitrile (AN), butyl acrylate (BA) and dihydro dicyclopentadienyl acylate (DCPA) are from BASF and were used without further purification.

Mowiol 8/88 from Hoechst is a polyvinyl alcohol whose Viscosity as a 4% solution in water at 20 ° C 8 mPa / s (first Digit) is measured according to DIN 53015. The degree of hydrolysis of Mowiol is 88 mol% (last two digits).

Polybutylacrylate rubber grafted with styrene (designation MS-1) and styrene and acrylonitrile (95: 5) (designation MS-2) with the compositions to

was prepared as follows.

In the graft shell of styrene and acrylonitrile was the Composition of the grafting monomers changed accordingly.

graft rubber

The following approach was carried out under nitrogen with a Dispermat Stirred for 20 minutes at 7000 rpm. The Dipermat was from the Fa. VMA-Getzman and was equipped with a 5 cm toothed disc Provided.

Approach:
1174.2 g of water
220.5 g of a 10% Mowiol 8-88 solution in water
11.0 g of a 40% solution of the emulsifier in water
1080.5 g of n-butyl acrylate
22.1 g of dihydrodicyclopentadienyl acrylate
5.5 g dilauryl peroxide

100 g of a mixture of these emulsions were in a moderately ge Stirred (250 rpm) glass flask under nitrogen at 67 ° C presented and polymerized. The dosage of the remainder of the emulsion he followed over a period of 180 minutes. For 60 minutes further polymerized. Thereafter, 2492.7 g of water and 454.7 g a 10% Mowiol 8-88 solution in water followed the batch of 1515.7 g of styrene, with the addition of the monomer per Feed was made within 150 minutes. There were another 150 Minutes at 67 ° C followed by 210 minutes at 70 ° C, auspoly merized.

The particle size distributions of the dispersions were with a Microtac UPA 150 Laser Scattering Device, Manufacturer Leeds and Northrup determined.

Rubber MS-1 (shell of 100% styrene)

Results D (10) 0.6 μm D (50) 1.0 μm D (90) 2.6 μm

Rubber MS-2 (shell of 95% styrene and 5% acrylonitrile) D (10) 0.3 μm D (50) 0.7 μm D (90) 1.2 μm

Kraton G 1651

Kraton G 1651 is a block copolymer from Shell with the following structure:
Styrene-hydrogenated butadiene-styrene block copolymer. The styrene: rubber ratio is 32: 68.

Preparation of the blends

In a ZSK 30 extruder SPS and optionally Kraton G 1651 melted and the MS dispersion (MS-1, MS-2) with a Monopump pumped directly into the polymer melt. Along the Extruders were drained by stuffing screws the water and the  finished polymer melt discharged from the extruder, cooled and granulated.

Results

The results are shown in the attached table.

comment

As can be seen, the use of MSP rubber (MS-1, MS-2) a better combination of properties such as impact toughness, MVI, Young's modulus and yield and fracture stress as Kraton alone.  

Claims (6)

1. Thermoplastic molding compositions containing

• A) 30 to 99.9% by weight of a vinylaromatic polymer having a syndiotactic structure
• B) 0.1 to 70 wt .-% of a rubber-elastic, particulate graft polymers
• C) 0 to 69.9 wt .-% of a rubber-elastic divide styrene / diene block copolymers whose Dient part may be completely or partially hydrogenated, wherein the particles of component B) has a D (50) value in the range of 0.1 to 10 μm and component B) is different from component C).

2. Thermoplastic molding compositions according to claim 1, wherein the compo nente B) by the method of microsuspension is available. 3. Thermoplastic molding compositions according to claims 1 to 2, wherein more than 50 number% of component B) in the molding composition not agglomerated. 4. Thermoplastic molding compositions according to claims 1 to 3, wherein the amount of component C) is in the range of 0 to 30 wt .-%, based on the molding composition is. 5. Use of thermoplastic molding compositions according to Claims 1 to 4 for the production of fibers, films and Moldings. 6. Fibers, films and moldings available from the Thermoplastic molding composition according to claims 1 to 4.