WO2006053711A1

WO2006053711A1 - Tenacious moulded masses containing fillers and based on styrol polymers

Info

Publication number: WO2006053711A1
Application number: PCT/EP2005/012232
Authority: WO
Inventors: Graham Edmund Mc Kee; Hans-Jürgen RENNER; Daniel Wagner; Chris Dearmitt
Original assignee: Basf Aktiengesellschaft
Priority date: 2004-11-17
Filing date: 2005-11-15
Publication date: 2006-05-26

Abstract

The invention relates to a mixture containing A) between 35 and 95 wt. % of a styrol polymer selected from acrylic nitrile butadiene styrol polymer (ABS), acrylic nitrile styrol acrylic ester polymer (ASA), and standard (GPPS) or impact-resistant polystyrol (HIPS) or mixtures thereof, B) between 1 and 10 wt. % of a styrol butadiene block copolymer consisting of at least two polystyrol blocks S and at least one styrol butadiene copolymer block S/B, and C) between 4 and 55 wt. % of an inorganic filler, the sum of A), B) and C) amounting to 100 wt. %. The invention also relates to methods for producing and using said moulded bodies for fibres, films, moulded bodies and foamed materials.

Description

Tough, filler-containing molding compositions based on styrene polymers

description

The invention relates to a mixture containing

A) 35 to 95 wt .-% of a styrene polymer selected from acrylonitrile-butadiene-styrene polymer (ABS), acrylonitrile-styrene-acrylic ester polymer (ASA), standard (GPPS) or impact-modified polystyrene (HIPS) or mixtures thereof, B) 1 to 10% by weight of a styrene-butadiene block copolymer which consists of at least two polystyrene blocks S and at least one styrene-butadiene copolymer block S / B,

C) 4 to 55% by weight of an inorganic filler,

wherein the sum of A), B) and C) gives 100 wt .-%.

Impact-resistant thermoplastic styrene-acrylonitrile copolymers (SAN) with graft rubbers based on polybutadiene or acrylic esters are known to the person skilled in the art as ABS or ASA. To change the property profile, these are also processed into blends with other thermoplastic polymers, in particular polycarbonate (PC) or polyamide (PA).

WO 00/36010 describes thermoplastic molding compositions of ABS or ASA polymers which are mixed with elastomeric styrene-butadiene block copolymers to improve their flowability and at the same time have good mold release properties.

WO 03/11964 describes thermoplastic molding compositions of impact polystyrene and an elastomeric styrene-butadiene block copolymer having improved stress cracking resistance.

WO 99/46330 discloses mixtures of elastomeric and rigid styrene-butadiene block copolymers with polystyrene. Styrene-butadiene block copolymers with random copolymer blocks and a low 1,2-vinyl content are known from WO 97/40079 and WO 00/58380.

Fillers can be incorporated into thermoplastic molding compositions based on styrene polymers to change the physical properties. Often fillers, in particular fibrous fillers are used to increase the stiffness of the moldings. Furthermore, fillers and pigments are used to change the color, gloss or electrical conductivity of the molding compositions. As a rule, the toughness and stress cracking resistance of the molding composition decreases. The object of the present invention was to remedy the aforementioned disadvantages and to find filler-containing molding compositions based on styrene polymers, which in particular have a high degree of toughness even with thin molded parts. Furthermore, the molding compositions should have a matte surface.

Accordingly, the above mixture was found.

Most preferably, the mixture contains

A) 60 to 90% by weight of a styrene polymer,

B) 2 to 5% by weight of a thermoplastic elastomer based on styrene (S-TPE),

C) 5 to 35% by weight of an organic or inorganic filler,

wherein the sum of A), B) and C) gives 100 wt .-%.

Component A

Suitable styropolymers are the polymers known as acrylonitrile-butadiene-styrene polymer (ABS) or acrylonitrile-styrene-acrylic ester polymer (ASA). They usually consist of a styrene-acrylonitrile copolymer matrix (SAN) having an average molecular weight Mw in the range from 40,000 to 250,000 g / mol and a graft rubber. The SAN matrix can be obtained in a known manner by bulk, solution suspension, precipitation or emulsion polymerization. The graft rubber usually consists of a graft core of a polydiene or acrylic ester, to which a graft shell of styrene and acrylonitrile and / or methyl methacrylate is applied.

Also suitable are standard polystyrene (GPPS or homopolystyrene), impact polystyrene (HIPS) or mixtures thereof. Toughened polystyrene can be prepared by mass or solution polymerization of styrene in the presence of polybutadiene or styrene

Butadiene block copolymers are obtained. This results in a matrix of polystyrene with trapped rubber particles that can form different morphologies, eg. Capsule particles, salami particles or cellulosic particles, and may have different average particle sizes.

Component B

Suitable styrene-butadiene block copolymers which consist of at least two polystyrene blocks S and at least one styrene-butadiene copolymer block S / B are, for example, star-branched block copolymers, as described in EP-A 0654488. However, preference is given to block copolymers having at least two hard blocks S ₁ and S ₂ of vinylaromatic monomers having at least one intervening statis¬ soft block B / S of vinyl aromatic monomers and diene, wherein the proportion of hard blocks over 40 wt .-%, based on the total Block copolymer is and the 1, 2-vinyl content in soft block B / S is below 20%, as described in WO 00/58380.

As component B, however, particular preference is given to a styrene-butadiene block copolymer having elastomeric properties, so-called thermoplastic elastomers (S-TPE).

The S-TPE preferably has an elongation at break of more than 300%, particularly preferably more than 500%, in particular more than 600%, measured to ISO 527, and is present in an amount in the range from 40 to 95% by weight. , preferably 60 to 80 wt .-%, based on the stretch film, mixed. Particularly preferred are mixed as TPE-S is a linear or star-shaped styrene-butadiene block copolymer with external polystyrene blocks S and, between these, styrene-butadiene copolymer blocks with a random styrene / butadiene distribution (S / B) _random, or with a styrene gradient NDOM

(S / B) tapβrZU.

The total butadiene content is preferably in the range from 15 to 50% by weight, more preferably in the range from 25 to 40% by weight, the total styrene content is preferably in the range from 50 to 85% by weight, particularly preferably in the range of 60 to 75% by weight.

Preferably, the styrene-butadiene block (S / B) consists of 30 to 75% by weight of styrene and 25 to 70% by weight of butadiene. A block (S / B) particularly preferably has a butadiene content of 35 to 70% by weight and a styrene content of 30 to 65% by weight.

The proportion of the polystyrene blocks S is preferably in the range of 5 to 40 wt .-%, in particular in the range of 25 to 35 wt .-%, based on the total Blockcopoly¬ mer. The proportion of the copolymer blocks S / B is preferably in the range of 60 to 95 wt .-%, in particular in the range of 65 to 75 wt .-%.

Particularly preferred are linear styrene-butadiene block copolymers of the general structure S- (S / B) -S with one or more, lying between the two S blocks, a static styrene / butadiene distribution _having blocks (S / B) _raπ do _m - such block copolymers are of medium by anionic polymerization in a nonpolar Lösungs¬ with addition of a polar cosolvent or a potassium salt obtainable, for example as described in WO 95/35335 and WO 97/40079. The vinyl content is understood to be the relative proportion of 1,2-linkages of the diene units, based on the sum of the 1,2-, 1,4-cis and 1,4-trans linkages. The 1,2-vinyl content in the styrene-butadiene copolymer block (S / B) is preferably below 20%, in particular in the range from 10 to 18%, particularly preferably in the range from 12 to 16%.

Component C

Suitable inorganic fillers are, for example, titanium dioxide, talc, chalk, kaolin, carbon black, aluminum hydroxide, magnesium hydroxide, aluminum nitrite, aluminum silicate, barium sulfate, calcium carbonate, calcium sulfate, silica, quartz powder, aerosil, alumina, wollastonite or colored pigments

The mixtures may also contain conventional dispersing aids, such as low molecular weight waxes, for. B polyethylene waxes or stearates, such as magnesium or calcium stearate.

The mixture according to the invention can be carried out by mixing methods known per se, for example by adding component C to a melt of components A and B. It is expedient to use extruders, for. b. Single-screw or twin-screw extruders or other conventional plasticizing devices, such as Brabender mills or Banbury mixers.

The fillers are preferably used in so-called masterbatches. In this case, a filler concentrate in the component A and / or B or a low-viscosity polyolefin or wax in the highest possible concentrations incorporated and this then compounded in an extruder with the other components.

Preference is given to the viscosities of components A) and B), and the conditions for incorporation of component C), e.g. Shear, temperature or Abkühl¬ speed chosen so that the morphology shown in Figure 1 is formed.

FIG. 1 shows the electron micrograph of an ultrathin section of an inventive mixture of impact polystyrene (HIPS) (component A)) and styroflex (component B)), which contains 20% by weight of CaCO 3 (component C)). Kau¬ chuk particles (2) and CaCO ₃ (3) are embedded in the polystyrene matrix (1). The component B) can be seen in cross-section as threads (4) with an average length / diameter ratio of> 5, preferably> 10, particularly preferably> 15.

If appropriate, the mixture according to the invention may comprise further thermoplastic polymers, such as polyolefins, for example homo- or copolymers of ethylene or propylene, mono- or copolymers of acrylates, for example methyl methacrylate or polyphenylene ether.

By mixing in a chemical or physical blowing agent, for example an inorganic gas such as nitrogen or carbon dioxide, the mixtures according to the invention can be processed into foam strands or sheets.

The mixtures according to the invention are distinguished by the fact that the addition of relatively high amounts of inorganic fillers compensates for the drop in mechanical properties in the thermoplastic molding composition by component B) or even increases the toughness. Furthermore, the thermoplastic molding compositions are less sensitive to foreign polymers and impurities since component B) has good compatibility with various thermoplastic polymers, in particular with various styrene polymers and polyolefins.

The mixtures according to the invention can be processed by extrusion, injection molding, vacuum or glass molding or foaming to form sheets or moldings. They have a very matt surface and can also be processed into thin-walled molded parts, such as yogurt cups.

The mixtures according to the invention have a high resistance to stress cracking, in particular in contact with oils and fats. They are therefore suitable for the production of molded parts for refrigerators, e.g. for refrigerator interior trim.

Examples:

Starting Materials:

SB1: Styroflex® 2G66 (thermoplastic elastomer based on styrene

Butadiene block copolymers with statistical S / B middle block of BASF Aktiengesellschaft)

SB2: Styrolux 3G55 (star-branched styrene-butadiene block copolymer of 25 wt% butadiene and 25 wt% styrene).

PS486M: impact polystyrene from BASF Aktiengesellschaft (melt volume MVR = 4 ml / 10 min, at 200 ° C./5 kp)

PS495F: visual non-porous polystyrene from BASF Aktiengesellschaft (melt volume MVR = 9.5 ml / 10 min, at 200 ° C./5 kp) PS2710: impact polystyrene from BASF Aktiengesellschaft (melt volume MVR = 4 ml / 10 min, at 200 ° C./5 kp)

PS145D: Standard Polystyrene from BASF Aktiengesellschaft (melt volume rate MVR = 15 ml / 10 min, at 200 ° C / 5 kp)

CaCO ₃ : Carbitol 110 S, Imerys Company, Cornwall, England with a mean

Particle size of 2 microns and a coating of stearic acid.

CaCO ₃ -batch: 60% by weight batch of calcium carbonate (Carbital 110S), prepared by melt extrusion with PS 495F on a ZSK 30 extruder.

TiO ₂ batch: 60% by weight of TiO ₂ and 40% by weight of standard polystyrene 158K (BASF AG)

Examples 1 to 4, Comparative Experiments V1 to V3

Mixtures with the indicated in Table 1 were mixed 30 extruder rpm at a temperature of 240 ° C at 200 and injection-molded at 22O ⁰ C in a ZSK. The mold temperature was 45 ° C.

The notched impact strength was measured according to ISO 179-2 / 1 EA (F).

The biaxial toughness was measured in the puncture test on 2.1 mm or 1.05 mm thick platelets in accordance with ISO 6603-2 / 40/20 / C.

Yield stress, tear strength and elongation at break were determined in the tensile test according to ISO 5270-2: 1993.

The mechanical data of Examples 1 to 6 according to the invention and Comparative Experiments V1, V2 and V3 are summarized in Table 1.

Table 1

Example 5, Comparative Experiment V4

Mixtures having the compositions shown in Table 2 were extruded directly in a ZSK 30 extruder at a temperature of 240 ^° C. at 200 rpm into plates having a thickness of 1.2 mm. The plates were then thermoformed into beakers at a cycle time of 39 cups per minute. The diameter at the upper edge was 6.8 mm and at the lower bottom 5.4 mm. The wall thickness varied between 0.15 and 0.2 mm thickness.

Table 2 shows the gloss values which were determined at a measuring angle of 60 ° in accordance with DIN 67530 with a microgloss reflector (BYK-Gardener GmbH, Geretsried) on the beakers).

The substitution of 3 parts by weight of polystyrene PS 486 (V4) with the styrene-butadiene block copolymer SB1 (B5) doubles the bursting pressure with only a slightly reduced breaking force. Table 2

Examples 6 and 7, Comparative Experiments V5 and V6

Mixtures with the compositions given in Table 3 were mixed in a ZSK 30 extruder at a temperature of 22O ⁰ C at 200 rpm and granu¬ profiled. From the granules 3 mm thick shoulder bars were pressed at 17O ⁰ C and 200 bar.

To evaluate the stress cracking resistance (ESCR), the elongation at break determined on the basis of the "flexural strip method" described in ISO 4599. For this purpose, the injection molded tensile test bars were stretched over bending templates with the radius 170 mm and a) 50 minutes in an autoclave at 300 mbar Exposed to pressure of a cyclopentane atmosphere (CP) or b) coated the surface under tension with a mixture of olive oil / oleic acid (1: 1), stored for 24 h and then measured in the tensile test according to ISO 527. As reference Tensile test bars measured without media (air).

Table 3

Claims

claims

1. mixture containing

A) from 35 to 95% by weight of a styrene polymer selected from acrylonitrile

Butadiene-styrene polymer (ABS), acrylonitrile-styrene-acrylic ester polymer (ASA), standard (GPPS) or impact-modified polystyrene (HIPS) or mixtures thereof,

B) 1 to 10 wt .-% of a styrene-butadiene block copolymer, which consists of at least two polystyrene blocks S and at least one styrene

Butadiene copolymer block S / B is,

C) 4 to 55% by weight of an inorganic filler,

wherein the sum of A), B) and C) gives 100 wt .-%.

2. Mixture according to claim 1, characterized in that the component B) from 15 to 50 wt .-% butadiene and 50 to 85 wt .-% styrene is constructed.

3. Mixture according to claim 1 or 2, characterized in that the styrene-butadiene copolymer block (S / B) of component B) is composed of 30 to 70 wt .-% of styrene and 25 to 70 wt .-% butadiene.

4. Mixture according to one of claims 1 to 3, characterized in that the styrene-butadiene copolymer block S / B of component B) has a statistical distribution of the styrene and butadiene units.

5. Mixture according to one of claims 1 to 4, characterized in that the 1, 2-vinyl content in the styrene-butadiene copolymer block (S / B) of component B) is un¬ ter 20%.

6. Mixture according to one of claims 1 to 5, characterized in that the proportion of the polystyrene blocks S in the range of 5 to 40 wt .-%, based on the component B), is located.

7. Mixtures according to one of claims 1 to 6, characterized in that it contains as component A) a styrene-butadiene block copolymer of the structure S- (S / B) -S.

8. Mixture according to one of claims 2 to 7, characterized in that it contains as inorganic filler titanium dioxide, talc, chalk, kaolin, aluminum hydroxide,

Magnesium hydroxide, aluminum nitrite, aluminum silicate, barium sulfate, calcium carbonate, calcium sulfate, silica, quartz powder, Aerosil, alumina, wollastonite or colored pigments.

9. foams, obtainable from a mixture according to any one of claims 1 to 8 by mixing a chemical or physical blowing agent and an¬ closing expansion.

10. A process for preparing a mixture according to any one of claims 1 to 8, characterized in that in an extruder, the component A and B melts and introduces the component C in the melt.

11. A process for preparing a mixture according to any one of claims 1 to 8, characterized in that one produces in a first step, a mixture of the components B) and C) and mixed in a second step with the component A).

12. Use of the mixtures according to one of claims 1 to 8 for the manufac turing of fibers, films, moldings and foams.