TALC-FILLED COMPOUND AND THERMOPLASTIC MOLDING MATERIAL

Abstract

Provided is a composition for producing a thermoplastic molding compound. The composition comprises the following: A) 35% to 85% by weight of aromatic polycarbonate, polyester carbonate, and/or polyester, B) 5% to 45% by weight of rubber-modified vinyl (co)polymer having a gel content measured as the proportion insoluble in acetone of 15% to 25% by weight based on the component B, C) 7% to 30% by weight of talc, D) 0.01% to 1% by weight of at least one dihydrogenphosphate salt having a cation selected from the group consisting of aluminum and zinc, and E) 0% to 10% by weight of polymer additives. Also provided is a process for producing a molding compound, a molding compound, a process for producing a molded article, a molded article, an autobody part, and a two-component injection molded part.

Claims

1. A composition for producing a thermoplastic molding compound, wherein the composition comprises the following: A) 35% to 85% by weight of aromatic polycarbonate, polyester carbonate, and/or polyester, B) 5% to 45% by weight of rubber-modified vinyl (co)polymer having a gel content measured as the proportion insoluble in acetone of 15% to 25% by weight based on the component B, C) 7% to 30% by weight of talc, D) 0.01% to 1% by weight of at least one dihydrogenphosphate salt having a cation selected from the group consisting of aluminum and zinc, and E) 0% to 10% by weight of polymer additives.

2. The composition as claimed in claim 1, wherein component A is aromatic polycarbonate.

3. The composition as claimed in claim 1, wherein the component B comprises polybutadiene-comprising rubber particles which are grafted with vinyl monomers and which contain inclusions of vinyl (co)polymer made of the vinyl monomers.

4. The composition as claimed in claim 1, wherein the component B comprises graft polymer having a core-shell structure having a core selected from the group consisting of silicone rubber, acrylate rubber, and silicone-acrylate composite rubber.

5. The composition as claimed in claim 4, wherein the proportion of the graft polymer having a core-shell structure having a core selected from the group consisting of silicone rubber, acrylate rubber, and silicone-acrylate composite rubber is chosen such that it contributes to the gel content measured in acetone of the component B to an extent of at least 70%.

6. The composition as claimed in claim 1, wherein zinc bis(dihydrogenphosphate) is employed as component D.

7. The composition as claimed in claim 6, wherein zinc bis(dihydrogenphosphate) in the form of the dihydrate Zn(H.sub.2PO.sub.4).sub.2.2H.sub.2O is employed as component D.

8. A process for producing a molding compound, comprising mixing the constituents of a composition as claimed in claim 1 with one another at a temperature of 200 C. to 320 C.

9. A molding compound obtained or obtainable by a process as claimed in claim 8.

10. A process for producing a molded article comprising utilizing the composition as claimed in claim 1.

11. A molded article, comprising the composition as claimed in claim 1.

12. An autobody part comprising a thermoplastic molding compound having a modulus of elasticity according to ISO 527 at 23 C. of at least 4500 MPa, a CLTE.sub.longitudinal according to DIN 53752 in the temperature interval of 23-55 C. of not more than 40 ppm/K, a longitudinal shrinkage according to ISO294-4 of not more than 0.4%, and an impact strength according to ISO 180/U at 23 C. of at least 60 kJ/m.sup.2.

13. An autobody part comprising a thermoplastic molding compound having a modulus of elasticity according to ISO 527 at 23 C. of at least 4500 MPa, a CLTE.sub.longitudinal according to DIN 53752 in the temperature interval of 23-55 C. of not more than 40 ppm/K, a longitudinal shrinkage according to ISO294-4 of not more than 0.4%, and an impact strength according to ISO 180/U at 23 C. of at least 60 kJ/m.sup.2, wherein a molding compound as claimed in claim 9 is used as the thermoplastic molding compound.

14. A two-component injection molded part consisting of (i) an opaque frame or mounting part produced from a composition as claimed in claim 1 and (ii) a transparent or translucent window or part section in direct contact with (i).

15. The two-component injection molded part of claim 14, wherein the part is an automotive glazing part, lighting article, headlight, or transilluminable decorative or functional trim or display.

16. A process for producing a molded article, comprising utilizing the molding compound as claimed in claim 9.

17. A molded article, comprising the molding compound as claimed in claim 9.

18. The molded article of claim 11, wherein the molded article is an autobody part.

19. The molded article of claim 17, wherein the molded article is an autobody part.

20. A two-component injection molded part consisting of (i) an opaque frame or mounting part produced from a molding compound as claimed in claim 9 and (ii) a transparent or translucent window or part section in direct contact with (i).

Description

EXAMPLES

[0186] Component A:

[0187] Linear polycarbonate based on bisphenol A having a weight-average molecular weight Mw of 28 000 g/mol (determined by GPC in methylene chloride against a bisphenol A-polycarbonate standard).

[0188] Component B:

[0189] Mixture of

[0190] B-1) a styrene-acrylonitrile copolymer having an acrylonitrile content of 23% by weight and a weight-average molecular weight M.sub.w of 100 000 Da (determined by GPC in tetrahydrofuran with a polystyrene standard,

[0191] B-2) an ABS polymer produced by bulk polymerization having an A:B:S weight ratio of 24%:10%:66% having a gel content measured in acetone at room temperature of 19% by weight, wherein the sol fraction of the component B-2 that is soluble in acetone has a weight-average molecular weight M.sub.w of 125 000 Da measured by GPC in tetrahydrofuran with a polystyrene as standard and

[0192] B-3) a graft polymer produced by emulsion polymerization having a core-shell structure consisting of 75% by weight of a silicone-acrylate composite rubber as the core and 25% by weight of a polymethyl methacrylate shell having a gel content measured in acetone at room temperature of 90% by weight.

[0193] As a mixture of these three constituents, the component B has a gel content measured as the fraction insoluble in acetone at room temperature of 23% by weight. This gel fraction of the component B derives to an extent of 22% by weight from the bulk ABS component B-2 and to an extent of 78% by weight from the graft polymer having a core-shell structure B-3. The proportion of the component B-1 is 53% by weight based on B.

[0194] Component C:

[0195] Jetfine 3CA: Talc (Imerys S.A., France)

[0196] Component D1:

[0197] Fabutit 289: orthophosphoric acid absorbed on silica gel (Chemische Fabrik Budenheim KG, Germany). Over 4 h at 23 C. and at a relative humidity of 50% the component D1 exhibits a water absorption of 14% of the starting mass.

[0198] Component D2:

[0199] Fabutit 313: Calcium bis(dihydrogenphosphate) anhydrous=Ca(H.sub.2PO.sub.4).sub.2 (Chemische Fabrik Budenheim KG, Germany). Over 4 h at 23 C. and at a relative humidity of 50% the component D2 exhibits a water absorption of 1% of the starting mass.

[0200] Component D3:

[0201] Budit T21: Zinc bis(dihydrogenphosphate) dihydrate=Zn(H.sub.2PO.sub.4).sub.2.2H.sub.2O (Chemische Fabrik Budenheim KG, Germany). Over 4 h at 23 C. and at a relative humidity of 50% the component D3 exhibits a water absorption of 1% of the starting mass.

[0202] Component E1:

[0203] Irganox B900 (BASF, Germany): Stabilizer

[0204] (mixture of 80% Irgafos 168 (tris(2,4-di-tert-butylphenyl) phosphite) and 20% Irganox 1076 (2,6-di-tert-butyl-4-(octadecaneoxycarbonylethyl)phenol) (BASF AG)

[0205] Component E2:

[0206] Pentaerythritol tetrastearate (demolding agent)

[0207] Component E3:

[0208] Black Pearls 800 (Cabot Corp., Belgium): carbon black pigment

[0209] Production of the Molding Compounds and Test Specimens

[0210] The components were mixed in a ZSK-25 twin-screw extruder from Coperion (Stuttgart, Germany) at a melt temperature of 260 C. Unless otherwise stated the molded articles were produced at a melt temperature of 260 C. and a mold temperature of 80 C. in an Arburg 270 E injection molding machine.

[0211] Testing of the Molding Compounds

[0212] The IZOD impact strength was determined at 23 C. on test bars having dimensions of 80 mm10 mm4 mm according to ISO 180/U (2013 version).

[0213] Total energy absorption in the puncture test according to ISO 6603-2 (2002 version) was used as a measure for material ductility under multiaxial stress. This is performed at 23 C. on test specimens having dimensions of 60 mm60 mm2 mm.

[0214] Modulus of elasticity E and elongation at break were determined on dumbbells having dimensions of 170 mm10 mm4 mm at 23 C. according to ISO 527 (1996 version) at a strain rate of 1 mm/min (modulus of elasticity) or 5 mm/min (elongation at break).

[0215] Melt viscosity was determined at a temperature of 260 C. and a shear rate of 1000 s.sup.1 according to ISO 11443 (2014 version).

[0216] The coefficient of thermal expansion (CLTE) was determined longitudinally (CLTE.sub.longitudinal) and transversely (CLTE.sub.transverse) to the melt flow direction in the temperature interval of 23 C. r to 55 C. on test specimens having dimensions of 80 mm10 mm4 mm according to DIN 53752 (1980 version) at a heating rate of 3 K/min.

[0217] The mold shrinkage was determined longitudinally (longitudinal shrinkage) and transversely (transverse shrinkage) to the melt flow direction according to ISO294-4 (2003 version) on test specimens having dimensions of 60 mm60 mm2 mm and manufactured with a holding pressure of 500 bar.

[0218] Processing stability was determined via so-called thermal injection testing. Test specimens having dimensions of 60 mm40 mm2 mm were injection molded at melting temperatures of 260 C., 280 C. and 300 C. (mold temperature at 80 C. in each case) and assessed for the presence on the sheet surface of streaking as an indication of thermal decomposition.

[0219] The sheets produced at 260 C. are furthermore also used for assessment of surface quality. Only parts exhibiting a defect-free and homogeneous surface quality are suitable for class A surfaces.

[0220] Assessment of bubble formation under exposure to hot and humid conditions is carried out on the test specimens having dimensions of 60 mm40 mm2 mm which were produced using a high-gloss polished mold. These sheets were in each case subjected to a temperature of 40 C. or 90 C. and a relative atmospheric humidity of 95% in each case for three days in a conditioning cabinet. A visual examination was then performed according to the following basis of assessment:

[0221] ++ no bubbles whatsoever

[0222] + not more than 2 small bubbles per surface (60 mm40 mm)

[0223] 2 to 5 small bubbles per surface (60 mm40 mm)

[0224] more than 5 bubbles per surface (60 mm40 mm)

TABLE-US-00001 TABLE 1 Examples of inventive compositions 1 (V) 2 (V) 3 Composition (parts by weight) A 49 49 49 B 30 30 30 C 20 20 20 D1 0.2 D2 0.2 D3 0.2 E1 0.1 0.1 0.1 E2 0.65 0.65 0.65 E3 0.05 0.05 0.05 Properties Impact strength [kJ/m.sup.2] 52 66 72 Energy absorption in puncture 6 12 12 test [J] Modulus of elasticity [MPa] 4691 4753 4685 Elongation at break [%] 9 10 12 Melt viscosity [Pas] 227 215 228 CLTE.sub.longitudinal [ppm/K] 42 38 37 CLTE.sub.transverse [ppm/K] 60 60 59 Longitudinal shrinkage [%] 0.31 0.31 0.31 Transverse shrinkage [%] 0.35 0.35 0.33 Processing stability Yes Yes No Streaking at 260 C. Streaking at 280 C. Yes Yes No Streaking at 300 C. Yes Yes Yes Surface quality (260 C.) Streaking Streaking Defect-free Homogeneously matt suitable for class A No No Yes Bubble formation (after 3 d at + ++ 40 C./95% RH) Bubble formation (after 3 d at + ++ 90 C./95% RH)

[0225] The data from table 1 show that the inventive composition 3 achieves an advantageous combination of good mechanical and rheological properties, low CLTE, low and isotropic shrinkage and a good stability under hot and humid conditions. When the composition contains the component D3, processing stability is improved and surface quality is suitable for class A. Impact strength and stability under hot and humid conditions are also particularly good.