MXPA01001803A - Compositions for termoplast molding - Google Patents

Abstract

The proposed thermoplastic molding compositions contain: (A) from 20 to 90% by weight, preferably from 30 to 80%. by weight, particularly preferably from 40 to 75% by weight of a thermoplastic polymer, and (B) from 10 to 80% by weight, preferably from 20 to 70% by weight, particularly preferably from 25 to 60% by weight of a crosslinked rubber having two or more faces, wherein the polymer A has a viscosity index, measured in a solution, to the concentration in dimethyl formamide at 23 ° C, from 50 to 70 ml / g, preferably from 55 to 65% ml / g, and where at least 80% in preference number at least 85%. in number, particularly preferably at least 90% by number of rubber particles B in the dispersion, after preparation thereof, have a diameter of < 0.2 microns, preferably < 0.18 microns, particularly preferably < 0.15 micr

Description

COMPOSITIONS FOR THERMOPLASTIC MOLDING The invention relates to thermoplastic molding compositions made from a polystyrene-acrylonitrile polymer and from a cross-linked rubber having two or more phases, and to the molded materials produced therefrom, and also to a process for producing materials molded by co-extrusion.

In certain sectors of application for thermoplastic polymeric materials, in particular in the internal accessories of automobiles and in domestic, electrical and sports equipment, there is a growing demand for an opaque, non-reflective surface. This can be for decorative or safety reasons, for example, reduced brightness for the driver of a car, or to improve the operating characteristics - it is difficult to observe marks on opaque surfaces. However, most of the commercially available impact modified molding compositions provide molded parts with glossy surfaces. Opaque molded parts can be obtained by surface treatment of a finished molded part with normal gloss, for example by roughing by mechanical treatment, such as brushing or scraping, or etching, solvating or swelling, or by applying a matte coating. However, a common factor for all these processes is a disadvantageous additional operation in the finished molding. Molded parts with a matt surface can also be produced using tools or molds with a structured surface, but the structuring of the mold wears it in a comparatively fast way. The inorganic matting agents such as silica gel or limestone can be added to the polymers, but the disadvantage is the deterioration of the mechanical properties of the molded part. This adverse effect can be avoided by the addition of suitable organic matting agents. These are composed of particles of comparatively large diameter (D> about 0.5 μ) dispersed in matrix polymers. The particles protrude to some degree from the smoothness and thus the glossy surface of the matrix polymer and thus create a diffuse reflection of the incident light (scattering), so that for an observer the surface appears matt. Many applications require polymers that are both matte and impact resistant. If a rigid, brittle polymer is to be modified in this way in an individual operation, the large matte particles must at the same time have elastomeric properties. To make the matte rubber particles compatible at least to some degree with the non-elastic matrix polymer, the former will normally have to be provided with a grafted cover made of a polymer with some degree of compatibility. EP-A 269 324 discloses graft polymers of this type which have large particle diameters and are elastomeric and also have a matt effect. However, the process for preparing the particles is very laborious, a first step prepares the elastomeric core particles, and in a subsequent step there is a swelling with newly added monomer, and then the polymerization is continued. This procedure is repeated, if desired, until the required particle size is obtained, and then the grafted cover is produced. EP-A 576 960 provides another way of obtaining matt and impact resistant molded material compositions, by producing relatively large particles through the agglomeration of small particles of grafted polymers whose grafted core consists of acidic groups and whose shell consists of basic groups, or vice versa. However, in some cases, only a limited matte effect is obtained through this way. Another requirement that is placed on the surface properties of polymeric molded materials is generally that they are uniform, with no flow lines, grooves and marks. An object of the present invention is to provide compositions for thermoplastic molding whose surface properties are improved and which are matte and without flow lines. We have found that this objective is achieved by thermoplastic molding compositions containing: A) from 20 to 90% by weight, preferably from 30 to 80% by weight, particularly preferably from 40 to 75% by weight of a thermoplastic copolymer composed of units from: a) from 60 to 85% by weight, preferably from 63 to 81% by weight , particularly preferably from 65 to 80% by weight of styrene and / or substituted styrene, in particular a-methylstyrene, a2) from 15 to 40% by weight, preferably from 19 to 37% by weight, particularly preferably from 20 to 35% by weight acrylonitrile, and a3) from 0 to 25% by weight, preferably from 0 to 20% by weight, particularly preferably from 0 to 18% by weight of other monomers copolymerizable with al and a2, and B) from 10 to 80% by weight, preferably from 20 to 70% by weight, particularly preferably from 25 to 60% by weight of a grafted rubber, crosslinked having two or more phases and composed of: bl) from 30 to 90% by weight, preferably from 40 to 70% by weight, particularly preferably from 45 to 70% by weight of a phase prepared by emulsion or mini-emulsion polymerization of: bl.l) from 80 to 100% by weight, preferably from 90 to 100% by weight, particularly preferably from 95 to 100% by weight of an acrylate, and bl.2) from 0 to 20% by weight, preferably from 0 to 10% by weight, particularly preferably from 0 to 5% by weight of other monomers, and b2 ) from 10 to 70% by weight, preferably from 30 to 60% by weight, particularly preferably from 30 to 55% by weight of at least one other phase prepared by polymerization of: b2.1) from 60 to 85% by weight , preferably from 70 to 80% by weight, of styrene, b2.2) from 15 to 35% by weight, preferably from 20 to 30% by weight of acrylonitrile, and b2.3) from 90 to 20% by weight of other monomers, in the presence of the first phase. In compositions for thermoplastic molding, polymer A has a viscosity index, measured in a solution at 0.5% concentration in dimethylformamide a 23 ° C, from 50 to 70 ml / g, preferably from 55 to 65 ml / g, and at least 80% by number, preferably at least 85% by number, particularly preferably at least 90% by number of the rubber particles B in the dispersion, after the preparation of this, has a diameter of < 0.2 μ, preferably < 0.18 μ, particularly preferably less than 0.15 μ. This class of products is known as ASA since it is composed of acrylonitrile, styrene and an acrylate. Surprisingly, it has been found that by processing the molding compositions made of a polystyrene acrylonitrile matrix and, embedded therein, crosslinked rubber particles, a rough surface is obtained which disperses the light and therefore has a matte appearance, with particles of small diameter rubber dispersed in the polystyrene-acrylonitrile matrix.

It has also been found that the surface of the resulting molded materials after co-extrusion with other plastics, in particular ABS, is free of flow lines if used, a free-flowing polystyrene-acrylonitrile matrix. Component A in novel compositions for thermoplastic molding is from 20 to 90% by weight, preferably from 30 to 80% by weight, particularly preferably from 40 to 75% by weight of a thermoplastic polymer composed of units from: ) from 60 to 85% by weight, preferably from 63 to 81% by weight, particularly preferably from 65 to 80% by weight of styrene and / or substituted styrene, in particular a-methylstyrene, a2) from 15 to 40% by weight, preferably from 19 to 37% by weight, particularly preferably from 20 to 35% by weight of acrylonitrile and, a3) from 0 to 25% by weight, preferably from 0 to 20% by weight, particularly preferably from 0 to 18% by weight of other monomers copolymerizable with al and a2. Other a3) modifiers whose use is preferred are acid (meth) acrylic and / or its derivatives, in particular methyl methacrylate, acrylamide and / or methacrylamide, and also maleic anhydride and / or phenylmaleimide. The component B in the compositions for thermoplastic molding is from 10 to 80% by weight, preferably from 20 to 70% by weight, particularly preferably from 25 to 60% by weight of a crosslinked grafted rubber having two or more phases and compound from: bl) from 30 to 90% by weight, preferably from 40 to 70% by weight, particularly preferably from 45 to 70% by weight of a phase prepared by emulsion or mini-emulsion polymerization of: bl.l) from 80 up to 100% by weight, preferably from 90 to 100% by weight, particularly preferably from 95 to 100% by weight of an acrylate, and bl.2) from 0 to 20% by weight, preferably from 0 to 10% by weight, particularly preferably from 0 to 5% by weight of other monomers, and b2) from 10 to 70% by weight, preferably from 30 to 60% by weight, particularly preferably from 30 to 55% by weight when minus another phase prepared by polymerizing: b2.1 ) from 60 to 85% by weight, preferably from 70 to 80% by weight of styrene, b2.2) from 15 to 35% by weight, preferably from 20 to 30% by weight of acrylonitrile, and b2.3) from 0 to 20% by weight of other monomers, in the presence of the first phase. The phase bl) of the cross-linked rubber B preferably has a vitreous transition temperature < 0 ° C, preferably < -10 ° C, particularly preferably < -15 ° C, and it is mainly (from 80 to 100% by weight, preferably from 90 to 100% by weight, particularly preferably from 95 up to 100% by weight) composed of acrylates, in particular butyl acrylate and / or ethylhexyl acrylate. This rubber phase bl) may contain other monomers bl.2), in particular methacrylates, styrene and / or acrylonitrile. Particularly preferred monomers bl.2) are polyfunctional crosslinking monomers, preferably selected from the following group: divinylbenzene, diallyl maleate, diallyl fumarate, diallyl phthalate, allyl methacrylate, triallyl isocyanurate, butadiene, isoprene and dihydrodicyclopentadienyl acrylate , particularly preferably dihydrodicyclopentadienyl acrylate. The rubber phase bl) is prepared by emulsion polymerization of the monomers or by mini-emulsion polymerization. The rubber B has at least one other phase, prepared by polymerizing: b2.1) from 60 to 85% by weight, preferably from 70 to 80% by weight of styrene, b2.2) from 15 to 35% by weight, preferably from 20 to 30% by weight of acrylonitrile, and b2.3) from 0 to 20% by weight of other monomers, in the presence of the first phase. The substances suitable for the other monomers b2.3) are those mentioned in bl.2) as other monomers for the first phase. The second phase b2) is generally the external phase of rubber B, that is, rubber B is generally a core-shell polymer, but this structure is not essential. The rubber phase b2) is preferably compatible at least to some degree with the matrix component A in the compositions for thermoplastic molding. The rubber B can also have other polymer phases, in particular made from polystyrene or its copolymers, preferably prepared from polystyrene and cross-linking agents and / or graft-forming monomers. These phases can be external covers or even the rubber particle cores B having two or more phases. The viscosity index or number of polymer A was measured in accordance with DIN 53726 in a solution at 0.5% concentration of the polymer in dimethylformamide at 23 ° C. The diameters of the rubber particles B, and also the number of these, was determined using ultra analytical centrifuge and the method of. Scholtan and H. Lange, Kolloid-Z. und Z -polymere 250 (1972) pp 782-796. The ultra centrifugal measurement provides the distribution of the integral mass or the distribution of the particle diameter number in a sample. This can be used to calculate the percentage by number or weight of the particles having a diameter equal to or less than a specific value. If rubber B has a third phase, it is preferably composed of at least 80% by weight of styrene and / or derivatives thereof. This preferably forms the core or an intermediate shell of the polymer particles. The compositions for thermoplastic molding preferably have a flow rate when melted of at least 2 ml / 10 min, preferably at least 4 ml / 10 min. The flow rate when melted was determined in accordance with ISO 1133 at 220 ° C and with 10 kg. The invention furthermore relates to molded materials, in particular profiles, films or sheets, produced by co-extrusion from 0.1 to 50% by weight, preferably from 2 to 20% by weight of the compositions for molding as claimed. in any of claims 1 to 3 and 50 to 99.9% by weight, preferably from 80 to 98% by weight of a second thermoplastic molding composition formed from one of the following polymers: ABS, PVC, HIPS, SAN , ASA + PC or ABS + PC. For the purposes of the present invention, and as is known, the molded materials are the products, in particular molded parts and semi-finished products, of the processing of the molding compositions. The ratio of the speed, of the flow when melted from the first composition for molding to that of the second, according to ISO 1133 at 220 ° C and with 10 kg, it is preferably from 0.5 to 10, particularly preferably from 1 to 10. The acrylonitrile content of the first molding composition is preferably greater than the content of acrylonitrile of the second composition for molding. Particularly suitable molded materials are those whose rubber particles B have network morphology, ie, where at least 80% by number of the particles has a point of contact with another particle. The object of the invention is also achieved by the blends of the thermoplastic molding compositions defined above with up to 45% by weight of the thermoplastic molding compositions having the same chemical structure, but any desired viscosity index of polymer A and any size of the rubber particles B. The invention further provides a process for producing co-extruded molded materials, wherein the co-extruded molded parts are preferably thermoformed and where the processing temperature of the first molded composition preferably it is from 200 to 300 ° C, in particular from 210 to 280 ° C. The novel molding compositions are particularly suitable for producing profiles of windows, boxes, surfaces, roofs, boats, roofs or roof boxes. The invention is described in more detail below using working examples. The sheets or sheets co-extruded 100 cm wide and with a thickness of the ABS layer of 4 mm and a thickness of the ASA layer of 0.8 mm were produced using a main extruder of a propeller, the diameter of the propeller of 90 mm, the length of the extruder equal to 30 times the diameter of the propeller, at 190 ° C in the feed section, from 260 to 270 ° C in the nozzle and in the feeder block, and with a yield of approximately 150 kg / h and using a single-screw co-extruder, the propeller diameter 45 mm, the length of the extruder equal to 25 times the diameter of the propeller, at 210 ° C in the feed section and from 260 to 270 ° C in the nozzle and in the feeder block.

The matte surface color was evaluated using brightness measurements in accordance with DIN 67530 with a measurement angle of 60 ° C. The brightness of the ASA layer was measured, and the brightness of < 30% was rated as optically matt. The appearance was visually assessed for the flow lines.

Examples 1 to 5 (Comparative) The first thermoplastic molding composition used (ASA 1) was composed of 55% by weight of polystyrene-a.crylonitrile with a viscosity index of 80 ml / g and an acrylonitrile content of 35%, and 45% by weight of monodisperse butyl acrylate grafted rubber with a particle size of 0.5 μ. The grafted rubber was prepared by emulsion polymerization: in a first polymerization step a mixture of butyl acrylate (BA) and dihydrodicyclopentadienyl acrylate (DCPA) in a stepwise ratio of 98: 2 was polymerized. In another step of polymerization, the rubber particles obtained from the first step were grafted with styrene (S) and acrylonitrile (AN). The weight ratio SAN: BA + DCPA was 40:60. After the rubber dispersion had been prepared, more than 99% in number of the rubber particles had a diameter > 0.2 μ. The particle size distribution of the dispersion was measured using an ultra centrifuge. The dispersion of the grafted rubber was coagulated and the wet rubber from the centrifuge was mixed with a PSAN melted at 260 ° C in a Werner & Pfleiderer ZSK. In Comparative Examples 1 to 5 no changes were made to the orifice composition for thermoplastic molding ASA 1, which in each case was co-extruded with a second composition for different ABS molding as mentioned below: Example 1: ABS 1: viscosity index of the matrix 80 ml g, matrix acrylonitrile content 24%, rubber content 30%, melt flow rate at 220 ° C and with 10 kg = 6 ml / 10 min , weighted average diameter 0.35 μ.

Example 2: ABS 2: viscosity index of the matrix 80 ml / g, matrix acrylonitrile content 24%, rubber content 40%, melt flow rate at 220 ° C and with 10 kg = 3 ml / 10 min, weighted average diameter 0.35 μ.

Example 3: ABS 3: viscosity index of the matrix 80 ml / g, acrylonitrile content of the matrix 35%, rubber content 28%, melt flow rate at 220 ° C and with 10 kg = 45 ml / 10 min, weighted average diameter 0.35 μ.

Example 4: ABS 4: viscosity index of the matrix 80 ml / g, acrylonitrile content of the matrix 33%, rubber content 46%, weighted average diameter 0.35 μ.

Example 5: ABS 5: Cycolac® GPX 3700 from General Electric Plastics.

In all Comparative Examples 1 to 5, glossy surfaces of the leaves were obtained. In the other Comparative Examples, 6 to 10, the first thermoplastic molding composition used was an ASA 2 molding composition made from 55% by weight of polystyrene-acrylonitrile with a viscosity index of 80 ml / g and an acrylonitrile content of 35%, and 45% by weight of butyl acrylate grafted rubber with a particle size of 0.1 μ. The weight ratio SAN: BA + DCPA was 40:60. The molding composition was prepared in the same way as ASA 1. In the obtained ASA 2 dispersion, more than 99% in number of the particles had diameter > 0.2 μ. The ASA 2 molding composition was then extruded with each of the aforementioned second ABS 1 to ABS 5 molding compositions. In all of Examples 6 to 10, the surfaces of the co-extruded sheets were matte but showed flow lines.

Examples 11 to 15 (Inventive) The first molding composition (ASA 3) used was a prepared mixture of 55% by weight of polystyrene-acrylonitrile with a viscosity index of 60 ml / g and an acrylonitrile content of 35%, and % by weight of butyl acrylate grafted rubber. The butyl acrylate grafted rubber was the same as for ASA 2. The first ASA 3 molding composition was then co-extruded in turn with, as the second molding composition, each of the ABS molding compositions 1 to 5 before mentioned. In all of Examples 11 to 15 the co-extruded sheets obtained matte surfaces free of flow lines.

Claims (1)

1. CLAIMS A composition for thermoplastic molding containing: A) desire 20 to 90% by weight, preferably 30 to 80% by weight, particularly preferably 40 to 75% by weight of a thermoplastic copolymer composed of units from: a) from 60 to 85% by weight, preferably from 63 to 81% by weight, particularly preferably from 65 to 80% by weight of styrene and / or substituted styrene, in particular a-methylstyrene, a2) from 15 to 40% by weight weight, preferably from 19 to 37% by weight, particularly preferably from 20 to 35% by weight of acrylonitrile, and a3) from 0 to 25% by weight, preferably from 0 to 20% by weight, particularly preferably from 0 to 18% by weight of other monomers copolymerizable with al and a2, and B) from 10 to 80% by weight, preferably from 20 to 70% by weight, particularly preferably from 25 to 60% by weight of a grafted rubber , reticulated having two om s phases and compound of: bl) from 30 to 90% by weight, preferably from 40 to 70% by weight, particularly preferably from 45 to 70% by weight of a phase prepared by emulsion or mini-emulsion polymerization of: bl. l) from 80 to 100% by weight, preferably from 90 to 100% by weight, particularly preferably from 95 to 100% by weight of an acrylate, and bl.2) from 0 to 20% by weight, preferably from 0 to 10% by weight, particularly preferably from 0 to 5% by weight of other monomers, and b2) from 10 to 70% by weight, preferably from 30 to 60% by weight, particularly preferably from 30 to 55% by weight of at least one other phase prepared by polymerization of: b2.1) from 60 to 85% by weight, preferably from 70 to 80% by weight, of styrene, b2.2) from 15 to 35% by weight, preferably from 20 to 30% by weight of acrylonitrile, and b2.3) from 90 to 20% by weight of other monomers, in the presence of the first phase, wherein the polymer A has a viscosity index, measured in a solution at 0.5% concentration in dimethylformamide at 23 ° C, from 50 to 70 ml / g, preferably from 55 to 65 ml / g, and when less 80% by number, preferably at least 85% by number, particularly preferably at least 90% by number of the rubber particles B in the dispersion, after the preparation thereof, has a diameter of < 0.2 μ, preferably < 0.18 μ, particularly preferably less than 0.15 μ. The composition for thermoplastic molding as claimed in claim 1, wherein the rubber B has a third phase, which is preferably prepared by polymerizing at least 80% by weight of styrene and / or its derivatives. The composition for thermoplastic molding as claimed in claim 1 or 2, which has a melt flow rate of at least 2 ml / 10 min, preferably at least 4 ml / 10 min. A molded material, in particular a profile, film or sheet, produced by coextruding from 0.1 to 50% by weight, preferably from 2 to 20% by weight of a composition for molding as claimed in any of claims 1 to 3 , and from 50 to 99.9% by weight, preferably from 80 to 98% by weight of a second thermoplastic molding composition formed from one of the following polymers: ABS, PVC, HIPS, SAN, ASA + PC or ABS + PC The molded material as claimed in claim 4, wherein the melt flow ratio of the first molding composition to that of the second is from 0.5 to 10, preferably from 1 to 10. The molded material as claimed in FIG. Claim 4 or 5, wherein the acrylonitrile content of the first molding composition is greater than the acrylonitrile content of the second molding composition. The molded material as claimed in claims 4 to 6, wherein the rubber particles B have the network morphology. A process for producing molded materials as claimed in any of claims 4 to 7 by coextrusion. The process as claimed in claim 8, wherein the co-extruded molded parts are thermoformed. The process as claimed in claim 8 or 9, wherein the processing temperature for the first molding composition is from 200 to 300 ° C, preferably from 210 to 280 ° C.