Use of wax as lubricant for filler-filled synthetic resin

The present invention is based on German Patent Application No. 102004016791.5 filed on April 6, 2004 and is disclosed herein as fully described herein.

The present invention relates to the use of wax as a lubricant for thermosetting or thermoplastic synthetic resins containing fillers and containing waxes.

Fillers are generally powders or fibers of organic or inorganic origin dispersed in organic media, dispersions or emulsions to impart certain properties to individual final products or to reduce the cost of manufacturing them. It is a state product. The filler should be dispersed in inorganic and organic substances. Of particular importance are calcium carbonate, magnesium carbonate, aluminum silicate, silicon dioxide, magnesium silicate (talc), barium sulfate, sodium potassium aluminum silicate, metals and metal oxides, aluminum hydroxide, carbon black and graphite, wood flour and cork flour. , Wood Particles, Wood Fibers, Fiberglass and Natural Fibers [HP Schlumpf, Filler and Reinforcements, R. Gachter, H. Muller, Plastic Additives, 3rd Edition, Carl Hanser Verlag, Munich, 1993, pp. 525-591].

Fillers are used in a wide range of applications. Particularly here, synthetic resin applications, paints, coating materials, papers, building materials and adhesives can be mentioned. Depending on the application, various properties of the filler become a problem. Typical parameters are refractive index, binder absorbency, specific surface area, hiding power, wear resistance (wear resistance of processing machines), gloss, particle size, and particle size distribution. Especially in the case of fibrous fillers, the compatibility between the filler and the matrix is of particular interest. As an example, glass fiber is coated with a suitable substance to improve the bond between the two substances.

Over the last decade, fillers have continued to grow in importance in synthetic resin processing. Most recently, fillers are added primarily to reduce the cost of the final product or to improve the quality of the finished product. The effect of the filler on the processing properties or the properties of the finished product has then been utilized. Fillers can be used to optimize properties such as machining speed, dimensional stability, flammability, wear resistance, electrical tracking resistance or mechanical properties. In the field of synthetic resin processing, fillers are especially used in polyvinyl chloride, polyethylene and polypropylene, and also in rubbers (uncrosslinked and crosslinked, eg vulcanized natural and synthetic elastomers). Fillers are rarely added to engineering thermoplastics (polycarbonate, polymethylmethacrylate, polyamide, polystyrene, etc.).

Thermoplastic synthetic resins containing wood as a filler have been proven in a very wide range of application fields. The substances mixed in this case are high concentrations of wood flour, wood fibers or wood particles. Generally, in this case, the filler content is 50 to 90% by weight. Commercially available thermoplastic synthetic resins are used as matrix materials. Here, among others, polyvinyl chloride, polypropylene, and polyethylene of various qualities can be mentioned. Rarely, engineering thermoplastics are also used, such as polystyrene or other styrene-based polymers (eg ABS). In addition to the main ingredients mentioned above, some additives are also used in such applications to optimize their properties. For example, very small amounts of paraffin and amide wax are added to these mixtures as lubricants. This achieves a better surface profile. Polarized polypropylene wax is also used to improve the bond between the filler and the synthetic resin. Conventionally unsolved problems are poor dimensional stability due to the rapid aging of these substances when exposed to the weather and the absorption of water by the wood mixed in the synthetic resin. Moreover, the productivity achievable with conventional extruders has been very low. The production line speed is very slow compared to the prior art of other synthetic resin processing industries.

<p> An object of the present invention is to solve these drawbacks of the prior art.</p>

<p> Surprisingly, the present inventor has also found that the addition of wax to the filling-containing synthetic resin also brings benefits in terms of application technology. The use of suitable products can result in a smooth surface with high extrusion speeds in the extrusion process. In addition, the absorption of water by the hydrophilic filler is delayed and reduced. At the same time good dimensional stability is achieved.</p><p> Therefore, the present invention relates to the use of wax as a lubricant for filler-containing synthetic resins.</p><p> The wax is preferably a synthetic or natural wax.</p><p> Natural waxes are preferably petroleum waxes, montan waxes, animal waxes and vegetable waxes.</p><p> Synthetic waxes are preferably fatty acids, fatty acid esters, fatty acid amides, Fishertroph waxes, polyolefin waxes, and polar modified polyolefin waxes.</p><p> The natural wax is particularly preferably Montan wax.</p><p> Montan wax is a salt of ester wax and / or carboxylic acid. These are particularly preferably reaction products of montanwaxic acid and polyhydric low molecular weight alcohols.</p><p> These reaction products contain a mixture of montanwaxic acid, the above alcohol, a partial reaction product of montanwaxic acid and an alcohol, and a complete reaction product.</p><p> The alcohol is preferably ethylene glycerol, glycerol, butanediol, pentaerythritol, dipentaerythritol and / or trimethylolpropane.</p><p> Examples of advantageous natural waxes are vegetable waxes such as carnauba wax or candelilla wax, or animal origin waxes such as shellac wax. Suitable synthetic waxes are montan waxes that have been decolorized or, in some cases chemically modified, eg esterified and / or partially saponified. Suitable substances are described, for example, in Ullmann's Encyclopedia of Industrial Chemistry, 5th Edition, A 28, Weinheim, 1996, 2.2, 2.3, and 3.1-3.5, pp. 110-126.</p><p> Advantageous substances here are non-polar or polar fully synthetic waxes, such as polyolefin waxes. Non-polar polyolefin waxes can be produced by thermal methods by reducing the molecular weight of branched or unbranched polyolefins or by direct polymerization of olefins. An example of a polymerization method that can be used is the free group initiation polymerization method, in which the reaction of olefins, generally ethylene, at high temperature and high pressure results in waxes with relatively high or relatively low degree of branching. The method by which ethylene and / or higher 1-olefins are polymerized with an organometallic catalyst such as a Tigranatta catalyst or a metallocene catalyst results in unbranched or branched waxes. Suitable methods for producing olefin homo- and-copolymer waxes are, for example, Ullmann's Encyclopedia of Industrial Chemistry, 5th Edition, Volume A 28, Weinheim, 1996, Chapter 6.1.1 / 6.1.2 [High Pressure Polymerization (high). -pressure polymerization)), No. 6.1.3 Chapter [Ziegler-Natta polymerization, Metallocene-catalyzed polymerization, Polymerization using metallocene catalysts] and Chapter 6.1.4 [thermal processes for reducing molecular weight], pp. 146-154. Polar polyolefin wax can be obtained by appropriately modifying the non-polar wax, for example by oxidation with air or by polar olefin monomers such as α, β-unsaturated carboxylic acid and / or derivatives thereof, such as acrylic acid or maleic anhydride. Manufactured by grafting acid and / or substituted and / or unsubstituted styrene and / or vinylsilanes. It 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-waxed ethylene homo- and copolymer by an oxidation method. As an example, Ullmann's Encyclopedia of Industrial Chemistry, 5th Edition, Volume A 28, Weinheim, 1996, 1st An example suitable for Chapter 6.1.5, page 155 is provided.</p><p> Polyolefin waxes are preferably homo- and copolymers of various alkenes.</p><p> Polyolefin waxes are preferably homo- and copolymers of ethene and propene.</p><p> Polyolefin waxes are preferably homo- and copolymers produced with Ziegler-catalyzed or metallocene-catalyzed catalysts.</p><p> The polyolefin wax is preferably a polar-modified polyolefin wax.</p><p> The polar modified polyolefin wax is preferably an oxidation product or graft copolymer.</p><p> The polar modified polyolefin wax is particularly preferably an oxidation product.</p><p> The polyolefin oxide wax is preferably a product having a drip point of 90 to 170 ° C.</p><p> Oxidized polyolefin wax is particularly preferably a product having a drip point of 95-130 ° C.</p><p> The polyolefin oxide wax is preferably a product having a melt viscosity of 1 to 10,000 mPas at 140 ° C.</p><p> Particularly preferably, the polyolefin oxide wax is a product having a melt viscosity of 1 to 1000 mPas at 140 ° C.</p><p> The oxidized polyolefin wax is preferably a product having an acid value of 1 to 50 mg (KOH) / g.</p><p> The oxidized polyolefin wax is particularly preferably a product having an acid value of 5 to 30 mg (KOH) / g.</p><p> The amount of wax used advantageously is 0.05-10% by weight based on the entire composition.</p><p> A particularly advantageous amount of wax used is 1.0-6.0% by weight based on the entire composition.</p><p> The filler is preferably an inorganic and / or organic filler.</p><p> Preferred inorganic fillers are calcium carbonate, magnesium carbonate, aluminum silicate, silicon dioxide, magnesium silicate (talc), barium sulphate, sodium potassium aluminum silicate, metals and metal oxides and / or aluminum hydroxide.</p><p> Preferred organic fillers are carbon black and graphite, wood flour and cork flour, wood particles, wood fiber, fiberglass, natural fiber and / or organic pigments.</p><p> The amount of the filler used advantageously is 1 to 99% by weight based on the whole mixture. </p><p> A particularly advantageous amount of filler used is 50-90% by weight based on the total mixture. </p><p> The present invention also relates to a thermoplastic synthetic resin or a thermosetting synthetic resin containing 1 to 99% by weight of the filler coated with the wax.</p><p> In particular, a thermoplastic synthetic resin or a thermosetting synthetic resin containing 50 to 95% by weight of a wax-coated filler is advantageous.</p><p> Thermoplastic, vulcanizable synthetic resin (rubber) or thermosetting synthetic resin is polyvinyl chloride, high density polyethylene, low density polyethylene, linear and low density polyethylene, polypropylene, natural rubber, synthetic rubber, polycarbonate. , Polymethylmethacrylate, polyamide, styrene polymers and / or blends of various synthetic resins are advantageous.</p><p> There are various ways to introduce wax into the mixture. For example, the wax can be applied in the form of an aqueous dispersion at an existing or new stage of the method. It can also be applied by spraying the molten wax onto the filler. It is also possible to homogenize the mixture of filler and wax in a mixer (eg, a vane mixer). It is also possible to weigh or weigh the wax directly into the processing machine without pre-mixing so that contact between the individual components can only be achieved there.</p><p> Example: Commercially available wood particles are premixed with various waxes and mixed with commercially available polypropylene, then the mixture is blended in an extruder. The pelletized compounded substance is processed into a molded product by injection molding. These molded members are subjected to various experiments. Products readily available on the market are tested as comparative examples. These mixed formulations are labeled B and these are prior art.</p><p> The compounded substance A contains 70% by weight of wood particles, 37% by weight of PP and 3% by weight of adhesion promoter.</p><p> The compounded substance B contains 4% by weight of a commercially available wood / polypropylene-based additive and 70% by weight of wood particles, 3% by weight of an adhesion promoter and 23% by weight of PP.</p><p> The compounded substance C contains 4% by weight of polyethylene oxide wax and 70% by weight of wood particles, 3% by weight of an adhesion promoter and 23% by weight of PP as additives for wood / polypropylene.</p><p> The compounded substance D contains 4% by weight of Montan wax and 70% by weight of wood particles, 3% by weight of an adhesion promoter and 23% by weight of PP as additives for wood / polypropylene.</p><p> Particularly suitable wax features: Polyethylene oxide Wax: Drip point: Approximately 104 ° C Acid value: Approximately 17 mg (KOH) / g Viscosity: Approximately 300 mPas (120 ° C) Montan wax ester: Drip point: Approximately 76 ° C Acid Value: Up to 40 mg (KOH) / g Saponification: Approximately 148 g (KOH) / g Manufacture of compounded material: All powdered ingredients are mixed uniformly in a tumbler mixer. This mixture is processed into pellets using a biaxial screw extruder that rotates in the same direction. Water absorption was measured according to DIN EN ISO 62.</p><p><tables num="1"><img file="JP2005298819A_D0001.tif" /></tables></p><p> The test values listed in the table clearly show that the blended substances C and D have very good processability and the lowest water absorption.</p>