DE10331451A1 - High mineral oil content styrene polymers used e.g. in moldings, films or foams are obtained by screw extrusion mixing with mixers or kneaders at the oil introduction zones - Google Patents

Abstract

Production of styrene polymers with a mineral oil content >= 8 wt.% by mixing comprises: (a) using an extruder with one or more screws; and (b) introducing the mineral oil at >= 2 openings, there being mixing or kneading elements in the vicinity of the openings.

Description

• a) zum Vermischen ein Extruder mit einer oder mehreren Schnecken verwendet wird,
• b) dem Extruder das Mineralöl an mindestens zwei verschiedenen Zufuhröffnungen zugeführt wird, und
• c) der Extruder im Bereich der Mineralöl-Zufuhröffnungen, Mischelemente oder Knetelemente oder beides, aufweist.

The invention relates to a process for the preparation of mineral oil-containing styrene polymers having a mineral oil content of at least 8 wt .-% by mixing styrene polymer and mineral oil, characterized in that

• a) for mixing an extruder with one or more screws is used,
• b) the extruder is supplied with the mineral oil at at least two different feed openings, and
• c) the extruder in the range of mineral oil supply openings, mixing elements or kneading elements or both.

Farther the invention relates to those obtainable by the process containing mineral oil Styrenic polymers, their use as masterbatch, as well as masterbatches containing the mineral oil-containing Styrene polymers. After all the invention relates to thermoplastic molding compositions containing i) Styrene polymers with a mineral oil content from 0 to less than 8% by weight, and ii) the said mineral oil-containing ones Styrene polymers.

styrene polymers such as polystyrene (GPPS, general purpose polystyrene), impact polystyrene (HIPS, high impact polystyrene) or styrene-butadiene block copolymers can by adding mineral oil as an additive, to be optimized in their properties. Especially can be the mechanical properties of the styrene polymers, for example flowability and elongation at break, depending on the amount of mineral oil used set exactly.

Around Polymers with a defined amount of additive, e.g. Pigments or fillers, often, the additives are not as such, but rather used in the form of so-called masterbatches. Masterbatches contain beside a polymer (often identical to the polymer to be polymerized is) a big one Amount of additive. For example, for coloring of Polystyrene pigment masterbatches of polystyrene with up to 60% by weight Pigment content, used. Distribute dosed additives via Masterbatch more even and faster in the polymer, and less disturbing agglomerates are formed. Furthermore is the dosage of the additive due to the larger amount of substance easier, compared to the "undiluted" additive.

The Production of such masterbatches of styrene polymers and mineral oil as an additive is difficult as usual at mineral oil levels from about 6 to 8 wt .-%, phase separation in a polystyrene phase and a mineral phase he follows. U.S. Patent 3,235,529 discloses a flowable powder of styrene homo- or styrene and 10 to 40 wt .-% mineral oil, and teaches in bridge paragraph from column 1 to column 2 that such, highly oily Mixtures can not be produced in an extruder. Much more It is proposed to use as starting material a styrene polymer latex use, by spray drying a polymer powder of 0.25 to 5 microns Produce particle diameter, and then the powder in a tumbler or Mix a ribbon blender with the mineral oil. The procedure is awkward, because the polymer is not as usual Granules, but must be used as latex, energy-intensive, because the latex spray-dry is, and time consuming, because the mixing is discontinuous and the oil is slow and added in small portions shall be.

It The task was to remedy the disadvantages described. Especially the task consisted of an alternative process for the production styrene polymers of high mineral oil content.

The Procedures should require less energy and time, and especially continuous can be operated. Furthermore, the styrene polymer in its commercial Shape, e.g. as polymer powder or granules can be used.

Accordingly, became Found the initially defined method. Furthermore, the uses mentioned there, masterbatches and thermoplastic Molding compounds, found. Prefer embodiments of the invention are the dependent claims refer to.

When Styrenic polymers are all common Polymers based on styrene monomers suitable. As styrene monomers can all vinyl aromatic monomers are used, for example Styrene, α-methylstyrene, p-methylstyrene, ethylstyrene, tert-butylstyrene, vinylstyrene, vinyltoluene, 1,2-diphenylethylene, 1,1-diphenylethylene or mixtures thereof. Particular preference is given to using polystyrene (GPPS).

Suitable styrene polymers are also those which contain conventional comonomers in addition to the abovementioned styrene monomers, for example acrylonitrile, methacrylonitrile, vinyl chloride, C _1-20 -alkyl esters of acrylic acid or methacrylic acid such as methyl methacrylate (MMA), butyl acrylates (eg n-butyl acrylate), 2- ethylhexyl acrylate. Geeig Nete comonomers are also maleic acid, maleic anhydride, maleimides, vinyl ethers, vinyl formamide and other polymerizable comonomers.

The Preparation of the styrene polymers is carried out in known per se Manner, such as by mass, solution, Emulsion, suspension or precipitation polymerization the mono mers, or combinations of these types of polymerization. In As a rule, the radical, anionic or cationic initiators, as well as other auxiliaries, concomitantly.

The Styrenic polymers can be rubber-free or rubber-containing. The former includes polystyrene (GPPS), the latter become common as impact-resistant denotes, for example, impact polystyrene (HIPS) or Styrene-butadiene block copolymers. In a preferred embodiment the process is characterized in that as styrene polymer, Polystyrene (GPPS), impact resistant Polystyrene (HIPS), styrene-butadiene block copolymers, or mixtures thereof, is used. Particular preference is given to using GPPS.

The in the impact resistant Styrene polymers contained rubbers are especially those based on diene monomers. As diene monomers are all polymerizable Dienes, in particular 1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 2,3-dimethylbutadiene, Isoprene, piperylene or mixtures thereof. Preference is given to 1,3-butadiene (in short: butadiene).

When Rubbers are especially homo-polybutadiene and styrene-butadiene copolymers. Homopolybutadienkautschuk receives in a manner known per se, e.g. by solution or emulsion polymerization in the presence of radical or anionic initiators.

at The copolymer rubbers are preferably block copolymers, for example Diblock copolymers S-B, triblock copolymers S-B-S and B-S-B, respectively, and Multi-block copolymers such as S-B-S-B-S, etc., where S is a Polystyrene block and B for a polybutadiene block is. The block copolymers can be used in in a manner known per se, e.g. through sequential anionic polymerization (sectionwise polymerization of the individual blocks successively with anionic initiator). The structure of the block copolymers can e.g. be linear, comb-like or star-shaped. Comb-like polymers are usually by grafting reactions, star polymers by Coupling reaction with a conventional Coupling agent obtained.

however can also be copolymer rubbers with random distribution of Monomer units, or with so-called tapered structure, use. Tapered means that along the polymer chain a gradient of e.g. styrolarm present in styrene-rich. Likewise, you can rubbers with the above block structure described in which, however, individual blocks statistically or tapered are constructed.

In As a rule, the rubber-containing (impact-resistant) styrene polymers have a rubber content from 0.1 to 12% by weight.

The rubber-free styrenic polymers preferably have weight average Molecular weights of 100,000 to 500,000, especially 120,000 up to 400,000 g / mol.

The Styrene polymers used as starting material can be the known additives and processing aids (short: additives) in the for this Substances usual Containing amounts, e.g. Lubricants or mold release agents, colorants such as. Pigments or dyes, flame retardants, antioxidants, Stabilizers against exposure to light, fibrous and powdery fillers or reinforcing agents or antistatic agents, as well as other additives, or mixtures thereof.

In particular, the styrene polymers used may also contain mineral oil in amounts of 0 to less than 8 wt .-%. It is therefore also possible to use those styrene polymers as starting material which are already weak, ie below 8% by weight, containing mineral oil. Such products are commercially available, for example, polystyrene ^® 143E from BASF. Such to less than 8 wt .-% mineral oil-containing styrene polymers can be used particularly advantageous if the product mineral oil-containing styrene polymers with a particularly high mineral oil content, for example 20 to 50 wt .-%, to be produced.

As mineral oil, all, usually from mineral resources (petroleum, lignite, coal, wood, peat) obtained, liquid distillation products are suitable. They usually consist of mixtures of saturated hydrocarbons and are unsaponifiable. Suitable mineral oils are, for example, gasoline, diesel oils, heating oils, lubricating oils, kerosene or insulating oils. Also liquid paraffins, ie mixtures of purified, saturated aliphatic hydrocarbons are suitable.

The suitable mineral oils preferably have a density of 0.75 to 1.0 g / ml according to DIN 51757 at 15 ° C., and a viscosity (kinematic) of 50 to 90 mm ² / s according to DIN 51562 at 40 ° C.

• – Dichte: ca. 0,867 g/ml bei 15°C nach DIN 51757
• – kinematische Viskosität: ca. 70 mm²/s bei 40°C nach DIN 51562
• – Erstarrungspunkt: ca. –9°C nach DIN/ISO 3016
• – Flammpunkt: ca. 266°C nach ISO 2592
• – unlöslich in Wasser.

Preferably used as mineral oils white oils, especially those which are approved as additives for styrene polymers (polystyrenes, etc.) with food contact, food law. Particularly preferably, for example, uses the white oil Winog ^® 70 from the company Wintershall AG, a mineral oil with the following properties.:

• - Density: approx. 0.867 g / ml at 15 ° C according to DIN 51757
• - kinematic viscosity: about 70 mm ² / s at 40 ° C according to DIN 51562
• - solidification point: about -9 ° C according to DIN / ISO 3016
• - Flash point: approx. 266 ° C according to ISO 2592
• - insoluble in water.

According to the invention, the mineral oil content of mineral oil Styrene polymers at least 8 wt .-%. Preferably, it is maximum 50% by weight. The mineral oil content is particularly preferably from 8 to 50% by weight, and in particular amounts he 10 to 50 wt .-%. Most preferably, it is 15 to 40% by weight.

in the Difference to the methods of the prior art is used in the method according to the invention an extruder with one or more screws for mixing the components styrene polymer and mineral oil (feature a) of the main claim).

As the person skilled in the art is an extruder of one or more Extruder screws constructed, which rotate in a housing cylinder. The snail usually consists of one or more screw elements (also referred to as screw segments), and the housing has Supply openings, through which the individual substances, here styrene polymer and mineral oil, in the Dosing extruder.

When Extruders are e.g. Single-screw extruder, twin-screw extruder, Ring extruder, or planetary roller extruder, as well as co-kneader and Farrel kneader, suitable. With two or more screws, the screws can be or turn in opposite directions, as well as combing or not combing be arranged. Preference is given to using a twin-screw extruder, particularly preferred with the same direction rotating and combing Snails.

Well For example, extruders of the ZSK type from Coperion are suitable (Werner & Pfleiderer) or other extruder whose screw configuration is simple Way to adapt. For example, in the ZSK extruder, the screw is produced after the Modular principle by arranging individual screw elements (e.g., conveyor threads, kneading blocks, etc.) and housing elements according to the desired Order and length the screw zones. The housing elements become common sealed with sealing elements against each other, for example such the company Reintz.

Of the Screw diameter D hangs naturally of the desired Throughput is usually 15 to 400, in particular 30 to 150 mm. In this case, the screw diameter be constant along the snail. But you can also snails whose diameter changes one or more times along the screw (widens or narrowed), the transitions between narrow and wide diameter can be long or short. Prefers If you use screws of constant diameter.

The overall length L of the screw (s) usually becomes specified as a multiple of the diameter D and is in the Rule 20 to 60 D, preferably 30 to 55 D.

For example, one-, two- or three-flighted screws may be used, with the number of flights along the screw being the same or different. The snails may have a small or large flight depth. The latter, so-called deep-cut screws usually have a flight depth ratio D _{worm outside} / D _{worm inside} of at least 1.4. Preference is given to using snails, which are continuously zweigängig and deeply cut.

The extruder temperature can usually be set separately in each extruder section by tempering the corresponding housing parts. Due to the introduced by the extruder screws energy (eg friction and shear energy), the extruder contents are heated and it may be necessary to To cool extruders or parts of the extruder. Preference is given to working in the region of the feed zone (see below), ie for example over a length of about 6 D from the start of the extruder at housing temperatures of 20 to 80 ° C, and in the remaining extruder section after the feed zone at 150 to 300, in particular 180 to 280 ° C housing temperature. The product temperature of the mineral oil-containing styrene polymers leaving the extruder is preferably from 150 to 300, particularly preferably from 180 to 280 ° C.

The Extruder speed is depending on the desired Throughput and the mixing behavior, preferably 100 to 1400, in particular 150 to 1200 rpm (revolutions per minute).

It has been shown that with increasing mineral oil content of the product higher temperatures and / or higher Speeds, each within the aforementioned ranges, advantageous are. higher Temperatures (e.g., 250 instead of 200 ° C) and / or higher Speeds (e.g., 300 to 600 instead of 150 rpm) facilitate mixing larger quantities of oil.

you can the inventive method in small or large throughputs (Feed) operate, for example at 5 to 4000, especially 10 up to 2500 kg / h, based on the product obtained.

The Styrene polymers are usually added to the extruder at the start of the screw supplied in the so-called feed zone, why usual Devices in use are, e.g. Hopper, Screw conveyors, or gravimetric or volumetric dosing devices. Usually enough for the styrene polymer from a single feed opening, but you can also two or more feed openings to which the total feed of the styrene polymer is divided becomes. In the field of styrene polymer supply conventional vents may be appropriate, if required.

Such supply ports for the Styrene polymers or vents counting as well as possibly at the extruder end existing degassing, Of course not to the mineral oil supply openings.

Usually is the styrene polymer feed opening before (upstream) the first mineral oil supply opening arranged. Preferred is the distance of the styrene polymer feed opening to first mineral oil feed opening 3 to 15, in particular 6 to 12 screw diameter D.

The Styrene polymer may be commercially available Form supplied to the extruder be, for example in solid form as granules, powder, chips, or similar. In particular, it is not necessary to use it as a solution or dispersion (emulsion or suspension).

The Plastification of the styrene polymer is usually done before first mineral oil intake in a so-called. Plastication zone, which is usually downstream of the feed zone lies. However, the styrenic polymer can also only partially or completely in the area of the first mineral oil supply be plasticized.

In the feed zone or plasticizing zone are the screws in usually as usual screw conveyors educated. usual screw conveyors are e.g. Screw elements with "Erdmenger" profile (completely self-cleaning), Sliding edge elements, elements with trapezoidal profile and elements with Rectangular profile, or combination of these elements.

According to the invention is the Extruder the mineral oil supplied at at least two different feed openings (feature b) of the main claim). Preference is given to using two, three or four feed openings, more preferably two or three. Three or more openings are particularly advantageous when products with high mineral oil contents, e.g. from about 25 wt .-%, to be produced.

The supply ports are designed in a manner known per se, e.g. as round, oval, elongated or polygonal openings (e.g., recesses or bores) of the extruder barrel. Openings, which are close to each other, for example, openings whose center areas maximum one screw diameter D are separated from each other, counting as a single feed opening in the sense of the claims. For example, you can have multiple openings close together, circular around the circumference of the extruder or along an imaginary helix around the circumference of the extruder, creating a "line", a "ring" or a "helix" of openings arises. Also such arrangements count as only one feed opening. However, every feed opening exists preferably only from a single opening.

In a preferred embodiment, the distance of the feed openings from one another is 3 to 15, in particular 6 to 12 D. If three feed openings used, the distance from the first to second opening preferably 6 to 12 D, and from the second to the third opening also preferably 6 to 12 D. The aforementioned distances are understood as distances of the center areas of the openings, or at feed openings, which consist of several closely spaced openings, as the distances each other next openings.

The mineral oil is usually with usual Devices through the supply openings introduced into the extruder, for example by means of pumps or other metering devices. The required pressure depends i.a. after the pressure of the Extruder content. The temperature of the metered mineral oil directs u.a. according to the viscosity of the oil and is preferably -20 up to 200, in particular 0 to 60 ° C, for example, room temperature (23 ° C).

The Distribution of the total amount of mineral oil added to the individual supply openings is variable. The following percentages by weight refer to the Mineral oil total. at two feed openings you add preferably from 10 to 90, in particular from 20 to 70,% by weight of the first opening to, and the remaining amount of the second supply port. At three feed openings are preferably 10 to 80 and in particular 20 to 70 wt .-% of first feed opening, 10 to 80 and in particular 20 to 70 wt .-% of the second opening and the remaining amount of the third opening, added. For example, you can get about 50% by weight in the first, about 40 wt .-% in the second and the remaining about 10 wt .-% in the third feed opening dosing.

at less than two feed openings the mixing of the styrene polymer with the mineral oil is not sufficient.

According to the invention the extruder in the area of mineral oil feed openings, mixing elements or kneading elements or both, on (feature c) of the main claim). The mixing elements or kneading effect an intimate mixing of the starting materials Styrene polymer and mineral oil, et al by applying shear forces and mix the extruder contents by shearing.

When Mixing or kneading elements come familiar to those skilled components considered, for example, screw elements with low slope in the conveying direction, kneading blocks with narrow or wide, promotional or non-promotional Kneading disks (so-called promotional or non-promotional Kneading blocks) Screw elements with a slope opposite to the conveying direction, or a combination of such elements.

As well are as mixing or kneading elements so-called. Backflowing elements (damming elements) suitable. They act as an obstacle to the extruder content, the pressure builds and mixes. backwater end Elements are known to the person skilled in the art. Examples are overlaid, promotional Screw elements, screw elements with slope against the conveying direction, kneading blocks with non-promotional Kneading disks in different widths, kneading blocks with recirculating pitch, kneading blocks with promotional Gradient, cylindrical discs, eccentric discs and configured therefrom Blocks, neutral baffles (throttle plates) and mechanically adjustable Throttles (sliding housing, Radial throttles, central chokes) called.

The Selection of mixing or kneading elements with regard to their type, number and dimensioning depends on the input materials and their Quantities, in particular according to the rheological behavior, the viscosity and softening temperature as well as the miscibility of the starting materials. Also, for example extruder speed and temperature, screw length L and screw diameter D, etc., to take into account.

at each of the mineral oil feeder openings can the mixing or kneading elements used by type, arrangement and Length equal or be different.

In a particularly preferred embodiment the method is characterized in that as mixing elements or kneading elements, promotional or non-promotional kneading blocks, backwater end Elements, or combinations of these components, are used.

Of the Claim text "im Range of Mineral Oil Feed Ports "means the Mixing or kneading elements are located near the feed opening, e.g. directly to (downstream) the feed opening. As well For example, an arrangement after and before (upstream) the feed opening may be advantageous be, especially if the pressure of the extruder contents that dosed - mostly much lower viscosity - mineral oil in the direction Helix start (upstream) to displace examined. Preferably, the mixing or kneading elements are in one Area that starts from 1 to 4, preferably 1 to 2 D before the feed opening and 1 to 9, preferably 2 to 6 D after the feed opening ends.

If required, can the snails outside of the area of mineral oil supply openings contain other mixing or kneading elements.

The Number or length the mixing or kneading elements may vary depending on the feed opening. In a preferred embodiment is the inventive method characterized in that per mineral oil supply opening the length of the Mixing or kneading 2 to 12 D, where D is the diameter the extruder screw is. Preferably, said length is 3 to 8 D.

If required, the extruder can one or more so-called. Entgasungszonen contain, in which volatile Accompanying substances if necessary under negative pressure, through degassing openings be removed. Such impurities are e.g. Residual monomers and -oligomers or solvent residues. The degassing zone is usually in the range after the last mineral oil intake, i.e. before the discharge zone. The discharge zone is usually a closed one Housing part, that with a defined discharge opening (for example nozzle plate) is completed, through which the product leaves the extruder. The nozzle plate For example, the product forms strands.

In the degassing and discharge zone are the worms usually as usual Screw conveyor formed, as already described above.

In a preferred embodiment the method is characterized in that the extruder leaving mineral oil-containing Styrene polymers, with a device for strand granulation, or for underwater granulation, granulated.

at strand pelletizing, the strands of product withdrawn from the nozzle plate are first passed through Air and then through a coolant bath (e.g., water bath) and thereby solidified. The solid strands are dried and in granulated in a conventional manner with a granulator.

at the underwater pelletizing will take place instead of the described combination from strand extract, water bath and granulator a special nozzle head with following Underwater granulation used. In this case, the polymer melt occurs through a nozzle plate, their outside is under water and the (preferably circularly arranged, round) has holes. The melt is rotating under water Knives separated and cooled by the water, the polymer to more or less round, pearled grains stiffens. The polymer grains are passing by Water carried away, separated and dried. In the arrangement the nozzle plate holes are other than circular Arrangements and other than round hole shapes in use, and you can instead Water also another coolant use.

The Underwater pelletizing can be done instead of the usual nozzle plate directly at the end of the extruder or you can use the extruder leaving the product a melt pump of Unterwassergranuliervorrichtung described respectively and granulate.

The water-side surface the nozzle plate is cooled by the water, what cause it can "freeze" the polymer already in the nozzle plate holes and the nozzle plate clogged. To prevent this, operate the nozzle plate in underwater granulation, preferably at a temperature around 5 to 60 ° C higher as the extruder temperature.

Around a consolidation of the strands to ensure, are in some cases lower cooling bath temperatures and / or longer Residence times in the cooling bath (i.e., a cooling bath greater length at strand pelletizing) is required than usual, not or low containing mineral oil Polymers. Preference is given to work at cooling bath temperatures of 5 to 70, in particular 10 to 60 ° C.

When Granulating device may also be used a Wasserringgranulierung become.

Of the Extruder can about it addition, more usual Devices, e.g. Melt filters, devices for Addition of additives, etc. Such additives are in the for this Substances usual Added quantities and have already been mentioned above in the description of the Styrene copolymers as additives and processing aids (in short: Additives) mentioned. The additives can Accordingly, be already contained in the starting material styrene polymer, or / and only in the method according to the invention added become.

Preferably, the method is to be designed in such a way and to operate the extruder such that the Mi neralöl is completely absorbed by the styrene polymer. In particular, it is to be operated so that no mineral oil drips or runs out of the extruder, and that the mineral oil-containing styrene polymer on its surface shows no exudation of mineral oil and no mineral oil film. For this purpose, preference is given to the process conditions, eg the starting materials and their quantities, the type, number and spacing of the feed openings, the temperature, the screw speed and number, the screw dimensions (length L and diameter D), the screw configuration (number and depth of flights, length and sequence of the screw elements, proportion of the mixing and kneading elements in the total length), etc., according to the above explanations optimized.

It It should be noted that the product, ie a styrene polymer with at least 8% by weight mineral oil content, only macroscopic (viewed with the naked eye) homogeneous is. Viewed microscopically, for example by electron microscopy it is heterogeneous: usually is a mineral oil phase dispersed in a styrene phase. This heterogeneity is apparent to the aforementioned Phase separation (separation or immiscibility) from a mineral oil content attributed from about 6 to 8 wt .-%, and leads to, that the product - im Unlike transparent GPPS or HIPS - usually due to the different refractive indices of the phases are not transparent is.

Of the Extruder should not stress the styrene polymer more than it does Achieve a macroscopically homogeneous product is required. In particular, the screw should no longer mixing or kneading and extruder temperature and speed should not be chosen higher, as for a good mixing is required. Otherwise, only could the styrenic polymer are thermally damaged, e.g. by thermal Degradation without improving the product quality.

object The invention also relates to the mineral oil-containing styrene polymers obtainable according to the described method. They have at least 8% by weight a much higher one mineral oil content on as usual containing mineral oils Styrene polymers containing only a maximum of about 7 wt .-% mineral oil.

As mentioned It is particularly preferred to use polystyrene (GPPS) as a styrene polymer one, and so much mineral oil, the product contains 8 to 50% by weight of oil. Accordingly, are mineral oil Styrene polymers of polystyrene and 8 to 50 wt .-% mineral oil especially prefers.

The styrene polymers according to the invention are characterized by an interesting property profile. Especially they have a very high flowability on, measurable e.g. as melt volume flow rate, MVR. Remarkably, it changes the glass transition temperature Tg not noticeable with increasing mineral oil content. Rather, she stays above the entire range of 8 to, for example, 50 wt .-% mineral oil content nearly constant at about 82 to 83 ° C, determined as described in the examples.

The mineral oil-containing invention Styrene polymers can used as such, e.g. for the production of moldings, films, Filming and foaming. However, they are preferred as relatively soft products used in admixture with other polymers, for example, blended with other styrenic polymers.

Prefers are the mineral oil-containing invention Styrene copolymers used as a masterbatch. With such a mineral oil masterbatch leaves the mineral oil content of a polymer precisely to adjust.

Inventive subject matter Accordingly, the use of the mineral oil-containing styrene polymers as masterbatch, and masterbatches containing the mineral oil-containing styrene polymers.

Prefers are the mineral oil-containing invention Styrene polymers as masterbatch for other styrenic polymers such as GPPS, HIPS, styrene-butadiene block copolymers, ABS (acrylonitrile-butadiene-styrene copolymer) or ASA (acrylonitrile-styrene-alkyl acrylate copolymer), or mixtures thereof, since they deal with such styrene polymers mix quickly and evenly in them to distribute.

The so-called masterbatches, ie the incorporation of the masterbatch in the other polymers that have a defined mineral oil content should be provided, can be done in a conventional manner, for example by mixing the components in a mixer, or by melting the solid polymer in an extruder, e.g. a so-called compounding extruder, or in a Banbury mixer, Kneader, roller mill or calender. However, the components can also be used "cold" and the powdery or granular mixture is only melted and homogenized during processing.

The with a masterbatch according to the invention blended GPPS is usually transparent.

• i) Styrolpolymere mit einem Mineralölgehalt von 0 bis unter 8 Gew.-%, und
• ii) die erfindungsgemäßen mineralölhaltigen Styrolpolymere.

Thus, the invention also relates to thermoplastic molding compositions containing

• i) styrene polymers having a mineral oil content of 0 to less than 8 wt .-%, and
• ii) the mineral oil-containing styrene polymers according to the invention.

there the proportions of i) and ii) depend on the desired mineral oil content of the final product resulting from the masterbatch.

Examples:

1. Feedstocks

It rubber-free polystyrenes (GPPS) were used, either free of mineral oil or at most 5.5% by weight Winog® 70 mineral oil (see below). Table 1 summarizes the properties.

Table 1: Polystyrenes used

• – Dichte: ca. 0,867 g/ml bei 15°C nach DIN 51757
• – kinematische Viskosität: ca. 70 mm²/s bei 40°C nach DIN 51562
• – Erstarrungspunkt: ca. –9°C nach DIN/ISO 3016
• – Flammpunkt: ca. 266°C nach ISO 2592
• – unlöslich in Wasser.

As the mineral oil, the white oil Winog ^® was 70 of Fa. Wintershall AG, is used. It had the following characteristics:

• - Density: approx. 0.867 g / ml at 15 ° C according to DIN 51757
• - kinematic viscosity: about 70 mm ² / s at 40 ° C according to DIN 51562
• - solidification point: about -9 ° C according to DIN / ISO 3016
• - Flash point: approx. 266 ° C according to ISO 2592
• - insoluble in water.

2. General Details of the extrusion

It a twin-screw extruder ZSK 30 from Fa. Coperion (Werner & Pfleiderer) was used. The screw diameter D was 30 mm. The snails turned in the same direction and were two-course. The polystyrene was introduced through a feed opening at the beginning of the extruder given to the extruder.

the Extruder was fed as much polystyrene and mineral oil that the product discharge 10 kg / h. The proportions Polystyrene / mineral oil, the extruder temperature T and extruder speed, as well as the properties are to be taken from the following tables.

It nb means value not determined, and V: for comparison.

3. Properties

The granules were processed by injection molding at a melt temperature of 220 ° C and a mold surface temperature of 45 ° C, unless otherwise stated below, to the corresponding test specimens. The following properties were determined:
Molecular weights: weight average Mw and number average Mn, determined by GPC (gel permeation chromatography), columns of divinylbenzene crosslinked polystyrene gel, type P1gel Mixed-B from Polymer Laboratories, eluent tetrahydrofuran, calibration with narrow polystyrene standards, detection by refractive index or UV.
Glass transition temperature Tg: determined by differential scanning calorimetry (DSC) under the following conditions: start temperature -100 ° C, stop temperature 180 ° C, heating rate 2 K / min, determination of Tg in the second run.
Melt volume flow rate MVR: determined on granules according to EN ISO 1133 at 200 ° C test temperature and 5 kg rated load, or at 190 ° C test temperature and 2.16 kg rated load.
Modulus of elasticity E, yield stress σ _S , fracture stress σ _R , and nominal elongation at break ε _R : each determined in a tensile test according to EN ISO 527 (DIN EN ISO 527-1 and 527-2) on specimens prepared according to EN ISO 3167 at 23 ° C, where the specimens were prepared at 220 ° C / 45 ° C, 240 ° C / 60 ° C or 260 ° C / 75 ° C (extruder temperature / tool surface temperature).
Penetration energy W _tot: determined in the penetration test according to EN ISO 6603-2 on specimens at 23 ° C, the test specimen at 220 ° C / 45 ° C, 240 ° C / 60 ° C or 260 ° C / 75 ° C (extruder temperature / Mold surface temperature). From the values, the average puncture work was calculated.
Oil separation: the granules were stored for 6 months at 23 ° C on nonwoven paper. Thereafter, granules and nonwoven paper were visually inspected for oil separation, ie exudation of mineral oil.

4. Production of high mineral oil content Polystyrenes (masterbatches)

Examples 1a to 1h: extruder with two mineral oil supply openings and strand granulation

The screw length L was about 32 D. The extruder had two feed ports for the Mineral oil on. There were about 60 wt .-% of the total mineral oil in the first Supply port, and the rest in the second opening, dosed.

in the Area of feed ports contained the piebald as mixing or kneading elements: promotional Knetblöcke, non-promotional kneading blocks, and backwatering Elements with a slope opposite to the conveying direction. 45% of the screw length existed from these mixing or kneading elements.

The exiting product was by strand granulation at 40 ° C water bath temperature solidified and granulated.

table 2 summarizes the data.

Table 2: Extruder with two mineral oil feed openings and strand granulation (nb not determined, V for comparison)

In No mineral oil was used in Examples 1a-V and 1f-V. They serve as Comparison and reference point. As the examples show, could be from different polystyrenes (PS1 and PS4) products with example 25% by weight mineral oil content produce.

Also after 6 months of storage, no oil separation took place on the granules by ausschwitzendes mineral oil observed.

Examples 2a to 2g: extruder with three mineral oil supply openings and underwater granulation

The screw length L was about 39 D. The extruder had three feed ports for the mineral oil on. About 50% by weight of the total amount of mineral oil was added to the first Supply port, about 40 wt .-% in the second opening and the remainder of about 10% by weight into the third orifice, dosed.

in the Area of feed ports contained the piebald as mixing or kneading elements: promotional Knetblöcke, non-promotional kneading blocks, and backwatering Elements with a slope opposite to the conveying direction. 51% of the screw length existed from these mixing or kneading elements.

The Escaping product was by underwater pelletizing with a Underwater pelletizer LPU from Fa. Gala at 50 to 60 ° C water temperature solidified and granulated. The nozzle plate temperature was 35 ° C above the Extruder temperature.

table 3 summarizes the data.

Table 3: Extruder with three mineral oil feed ports and underwater granulation (nb not determined, V for comparison)

The Examples show that with three mineral oil supply openings also products with very high mineral oil content - up to 40 wt .-% - produce left. Comparative Example 2a-V without metered mineral oil is used as a reference point. In Examples 2a-V to 2f the polystyrene PS2 was used, already 5.5% by weight of mineral oil contained. In example 2g could also from the mineral oil-free Polystyrene PS1 a product with 35 wt .-% mineral oil are produced.

5. Production mineral oil Polystyrenes by mixing the masterbatches according to the invention in polystyrene and comparison with commercial product

Example 3a: Masterbatch with 10 wt .-% mineral oil

Out the mineral oil-free Polystyrene PS1 and the masterbatch from Example 1b (mineral oil content 10 wt .-%) was in the usual Way a mineral oil-containing Polystyrene produced. The quantities of PS1 and masterbatch were chosen so that the polystyrene had a mineral oil content of 5.5 wt .-%.

The Product was at 45, 60 or 75 ° C Mold surface temperature to test specimens whose properties were determined as above described under 3..

Example 3b: Masterbatch with 20% by weight of mineral oil

It the procedure was as in Example 3a, wherein instead of the masterbatch from Example 1b, the masterbatch from Example 1d with 20 wt .-% mineral oil content has been used.

Example 3c-V: Comparison with commercial product

Around the properties of the polystyrenes prepared according to the invention from Examples 3a and 3b with a commercially available Polystyrene, the polystyrene PS2 was compared, a commercial one Product of the same composition, processed into test specimens and examined as described in Example 3a.

table 4 summarizes the results.

Table 4: mineral oil-containing polystyrenes of masterbatches according to the invention or commercial product (temperatures denote extruder / mold surface temperature, V for comparison)

All specimens were macroscopically homogeneous and crystal clear. Examples 3a to 3c-V show that the Properties of mineral oil-containing Polystyrenes consisting of masterbatches according to the invention and polystyrene that of a commercial product (Example 3c-V) on equal footing were.

6. Production mineral oil Polystyrenes by mixing the masterbatches according to the invention in polystyrene and comparison with direct mixing of the mineral oil

Examples 4b and 4d: mixing of polystyrene and masterbatch granules

Out the mineral oil-free Polystyrene PS1, the mineral oil-containing Polystyrene PS3 and the masterbatch from Example 1d (mineral oil content 20 wt .-%) were in the usual Way mineral oil-containing Polystyrenes produced. PS1, PS3 and Masterbatch were used as Granules used, and their amounts chosen so that the product in the mineral oil content indicated in the table had.

The product obtained by strand granulation was at 45, 60 or 75 ° C tool surface temperature to test specimens processed whose properties were determined as above described under 3..

Examples 4a-V and 4c-V: Comparison with commercial products

When Comparison served commercial Products of the same gross composition. They were in a reactor cascade have been prepared, the mineral oil as such during the Preparation of the polymer had been added. That the mineral oil content was in the inventive examples 4b and 4d via mineral oil masterbatch adjusted (so-called dry blend of "dry" granules), and in the comparative examples 4a-V and 4c-V by usual oil addition already during polymer production.

table 5 summarizes the results.

Table 5: mineral oil-containing polystyrenes from masterbatches according to the invention or by customary mineral oil addition (nb not determined, V for comparison)

Therefore they were over a mixture of granules produced, which the mineral oil - except for the in the PS3 already used, small amount of mineral oil - by Masterbatch added was (Examples 4b and 4d), as good mechanical properties on like the comparison products same mineral oil content, in which the mineral oil in the usual Added way had been (Example 4a-V and 4c-V).

Claims (11)

A process for the preparation of mineral oil-containing styrene polymers having a mineral oil content of at least 8 wt .-% by mixing styrene polymer and mineral oil, characterized in that a) for mixing an extruder with one or more screws is used, b) the extruder, the mineral oil at least two c) the extruder in the region of the mineral oil supply openings, mixing elements or kneading elements or both, has. Method according to claim 1, characterized in that as styrene polymer, polystyrene, impact-modified polystyrene, styrene-butadiene block copolymers, or mixtures thereof. Process according to claims 1 to 2, characterized that the mineral oil content 10 to 50 wt .-% is. Process according to claims 1 to 3, characterized that as mixing elements or kneading elements, promotional or non-promotional kneading blocks, backwater end Elements, or combinations of these components, are used. Process according to claims 1 to 4, characterized that per mineral oil feed opening the length of the Mixing or kneading 2 to 12 D, where D is the diameter the extruder screw is. Process according to claims 1 to 5, characterized that the extruder leaving mineral oil-containing styrene polymers, with a device for strand granulation, or for underwater granulation, is granulated. mineral oil-based Styrene polymers, available according to the method according to claims 1 to 6th mineral oil-based Styrenic polymers according to claim 7, of polystyrene and 8 to 50% by weight Mineral oil. Use of the mineral oil-containing styrene polymers according to the claims 7 to 8 as masterbatch. Masterbatches containing mineral oil Styrenic polymers according to the claims 7 to 8. Thermoplastic molding compositions containing i) Styrene polymers with a mineral oil content from 0 to less than 8% by weight, and ii) mineral oil-containing styrene polymers according to claims 7 to 8th.