Method for using wax as modifier for filler-including plastic

The present invention is described in German Patent Application No. 10 2004 016 790.7, which was filed on April 6, 2004, which is the basis of the priority claim. It is assumed that all the contents of this German patent application specification are published in this specification.

The present invention relates to a method of using a wax, which is used as a modifier in a thermoplastic or a thermosetting plastic containing a filler and the wax.

Fillers are generally powders of organic or inorganic origin that are dispersed in an organic medium, dispersion or emulsion for the purpose of imparting certain properties to each final product or reducing the cost of making it. Means a state substance. Fillers must be distinguished between inorganic and organic materials. Of particular importance are calcium carbonate, magnesium carbonate, aluminum silicates, silicon dioxide, magnesium silicates (talc), barium sulfate, sodium potassium aluminum silicates, metals, and metal oxides, aluminum hydroxides. , Carbon black and graphite, wood powder and cork powder, wood particles, wood fiber, fiberglass and natural fiber (HP Schlumpf, Filler and Reinforcements in R. Gaechter, H. Mueller, Plastic Additives, 3rd edition, Carl Hanser Verlag Munich 1993, pp. 525-591).

Fillers are widely used. Here, the applications particularly mentioned in relation to synthetic materials are: paints, coating materials, papers, building materials, and adhesives. Depending on the application, various properties of the filler are relevant. Typical parameters are refractive index, binder absorbency, specific surface area, opacity, wear (machine wear), gloss, particle size and particle size distribution. The compatibility of the filler with the matrix is particularly important, especially in the case of fibrous fillers. For example, in order to enhance the bond between these two materials, the glass fiber is coated with a suitable substance.

Over the last few decades, the importance of fillers in plastic processing has been constantly increasing. Initially, fillers were added primarily to reduce the cost of the final product or improve the quality of the finished product, but later, the effect of the filler on the processing properties or the properties of the finished product was utilized. It has been. Fillers can also be used to optimize properties such as machining speed, dimensional stability, flammability, wear resistance, electrical tracking resistance, or mechanical properties. In the field of plastic processing, fillers are used especially for polyvinyl chloride, polyethylene, and polypropylene, as well as rubbers (natural or synthetic non-crosslinked or crosslinked (eg, vulcanized) elastomers). There are relatively few examples of filler addition to engineering thermoplastics (polycarbonate, polymethylmethacrylate, polyamide, polystyrene, etc.).

Wood-filled thermoplastics are a well-established prior art for a wide variety of applications. At this time, the material to be mixed is high-concentration wood flour, wood fiber, or wood grain. In this case, a filler concentration of 50 to 90% by weight is usually used. Commercially available thermoplastics are used as the matrix material. Particularly mentioned in this case are polyvinyl chloride, polypropylene, and various grades of polyethylene. Also, less frequently, engineering thermoplastics are also used, examples of which are polystyrene or other styrene polymers (eg ABS). In addition to the above components, additives are also used in such applications for optimization of properties. For example, a very small amount of modified polymer is added to improve the mechanical properties. Previously unsolved problems are the aging of these materials in a short period of time due to weathering and the poor dimensional stability due to the absorption of water by the wood mixed in the plastic.

Surprisingly, it has been found that the addition of wax to filler-containing plastics provides performance benefits. By using suitable materials, a noticeably favorable effect on the property profile of the part can be obtained. The level of mechanical properties for tensile and bending stresses is improved.

In addition, the absorption of water by the hydrophilic filler is delayed and reduced. At the same time, better dimensional stability is achieved. Therefore, the present invention provides a method of using wax as an additive for filler-containing plastics.

The wax preferably consists of synthetic or natural wax.

The natural wax preferably consists of petroleum wax, montan wax, animal wax, and / or vegetable wax.

Synthetic waxes preferably consist of fatty acids, fatty acid esters, fatty acid amides, Fishertropus waxes, polyolefin waxes, and / or polar modified polyolefin waxes.

The natural wax preferably consists of montan wax.

Montan wax is an ester wax and / or salt of a carboxylic acid. These consist, in particular, of the reaction products of montanwaxic acid and multivalent low molecular weight alcohols.

Examples of preferred natural waxes here are vegetable waxes such as carnauba wax or candelilla wax, or animal-derived waxes such as shellac wax. Suitable semi-synthetic waxes are, for example, decolorized or, if appropriate, chemically modified (eg, esterified and / or partially saponified) montan waxes. Suitable materials are described, for example, in Ullmann's Encyclopedia of Industrial Chemistry, 5th Edition, Vol. A 28, Weinheim 1996, Chapters 2.2, 2.3 and 3.1-3.5, pp. 110-126.

At this time, the material preferably consists of a completely synthetic non-polar or polar wax, such as a polyolefin wax. Non-polar polyolefin waxes can be produced by reducing the molecular weight of branched or non-branched polyolefins by thermal methods or by directly polymerizing olefins. Examples of polymerization methods that can be used are free-based methods in which olefins, usually ethylene, are reacted at high pressures and high temperatures to give waxes with relatively high or low branching, or ethylene and / or higher grade 1s. -A method of polymerizing an olefin using an organic metal catalyst, for example, a Chigranatta catalyst or a metallocene catalyst to obtain a non-branched or branched wax. Suitable methods for producing olefin homo- or copolymer waxes are described, for example, in Ullmann's Encyclopedia of Industrial Chemistry, 5th Edition, Vol. A 28, Weinheim 1996, Chapter 6.1.1 / 6.1.2 (High Pressure Polymerization), Chapter 6.1.3 (Chigranatta Polymerization, Metallocene Catalyzed Polymerization) and Chapter 6.1.4 (To Reduce Molecular Weight) Thermal method), pp. 146-154. The polar polyolefin wax is produced by appropriately modifying the non-polar wax. For example, it can be oxidized with air or polar olefin monomers such as α, β-unsaturated carboxylic acids and / or derivatives thereof (eg acrylic acid or maleic anhydride), and / or substituted and / or unsubstituted. Manufactured by modification with a graft of styrene and / or vinylsilane. Polar polyolefin wax can also be produced by copolymerizing ethylene with a polar comonomer, such as vinyl acetate or acrylic acid, or by reducing the molecular weight of a relatively high molecular weight non-wax-like ethylene homo or copolymer by an oxidation method. it can. For example, Ullmann's Encyclopedia of Industrial Chemistry, 5th Edition, Vol. Appropriate examples are given in A 28, Weinheim 1996, Chapter 6.1.5, p. 155.

The polyolefin wax preferably consists of homo or copolymers of various alkenes.

The polyolefin wax preferably consists of homopolymers and copolymers of ethene and propene.

The polyolefin wax is preferably a homopolymer and copolymer produced with a tigler or metallocene catalyst.

The polyolefin wax preferably consists of a polar-modified polyolefin wax.

The polar modified polyolefin wax preferably consists of an oxidation product or a graft copolymer.

The graft copolymer preferably comprises a product produced from the above-mentioned polyolefin wax and one or more polar monomers by a free radical method. The monomer preferably consists of maleic anhydride, alkoxy-substituted vinylsilane, and styrenes.

The graft copolymer preferably consists of a product having a drop point of 90-170 ° C.

The graft copolymer is particularly preferably composed of a product having a drop point of 110-150 ° C.

The graft copolymer preferably consists of a product having a melt viscosity of 0.1-10000 mPas at a temperature of 170 ° C.

The graft copolymer is particularly preferably composed of a product having a melt viscosity of 1 to 1000 mPas at a temperature of 170 ° C.

The graft copolymer preferably consists of a product having a graft degree of 0.1-20%.

The graft copolymer is particularly preferably composed of a product having a graft degree of 2-10%.

The preferred amount of wax used is 0.05 to 10% by weight based on the filler.

A particularly preferable amount of wax used is 0.5 to 5.0% by weight based on the filler.

The filler is particularly preferably an inorganic filler and / or an organic filler.

The inorganic fillers are preferably calcium carbonate, calcium magnesium carbonate, aluminum silicates, silicon dioxide, magnesium silicates (talc), barium sulfate, sodium potassium aluminum silicates, metals and metal oxides, and / or water. It consists of aluminum oxide.

Organic fillers preferably consist of carbon black and graphite, wood flour and cork flour, wood grains, wood fibers, fiberglass and natural fibers, and / or organic pigments.

The preferred amount of filler used is 1 to 99% by weight based on the entire mixture.

A particularly preferred amount of filler used is 50-90% by weight based on the total mixture.

The present invention also provides a thermoplastic or a thermosetting plastic containing the above wax-coated filler in a proportion of 1 to 99% by weight.

The material preferably comprises a thermoplastic or thermosetting plastic containing a wax coating filler in a proportion of 50-95% by weight.

Vulcanizable thermoplastics (rubbers) or thermocurable plastics are preferably polyvinyl chloride, HD (high density) polyethylene, LD (low density) polyethylene, LLD (linear low density) polyethylene, polypropylene, natural rubber. , Synthetic rubber, polycarbonate, polymethylmethacrylate, polyamide, styrene polymer, and / or a blend composed of various plastics.

There are various methods of mixing wax into the mixture. For example, the wax can be applied in the form of an aqueous dispersion in an existing step of the process or in a newly established step. It is also possible to apply the wax melt to the filler by spraying. Mixtures composed of fillers and waxes can also be homogenized in a mixing device (eg, a blade mixer). It is also possible to add the wax directly into the processing machine by volumetric or gravimetric means without premixing, and only then bring the components into contact.

Commercially available wood grains were premixed with various waxes and commercially available HD polyethylene, and then the mixture was compounded in an extruder. These compounded and pelletized materials were processed by injection molding to obtain a molded product. These members were subjected to various tests. Products readily available on the market were used for testing as a comparison. Their mixed formulations are indicated by the symbol B, which represents the prior art.

The compounding material A is composed of 70% by weight of wood grains and 30% by weight of HDPE.

Formulation B consists of 1.5% by weight of commercially available additives for wood / polyethylene, 70% by weight of wood grains, and 28.5% by weight of HDPE.

The compounding material C is composed of 1.5% by weight of maleic anhydride-grafted metallocene polyethylene wax as an additive for wood / polyethylene, 70% by weight of wood grains, and 28.5% by weight of HDPE. Features of the new additive: Polyethylene wax produced using metallocene catalysis Drop point: Approximately 120 ° C Acid value: Approximately 40 mg KOH / g Viscosity: Approximately 220 mPas at 140 ° C Formulation: All powdery components, tumbling mixer Mixed uniformly in. This mixture was processed into pellets using a co-rotating twin screw extruder. Specimen Preparation: Standard dumbbell specimens according to DIN EN ISO 294 were injection molded for all tests.

Mechanical properties were measured according to DIN EN ISO178, DIN EN ISO179 and DIN EN ISO527. Water absorption was tested according to DIN EN ISO 62.

<tables num="1"><img file="JP2005298820A_D0001.tif" /></tables>

The above test values clearly show that compounding material C has the very best properties.