Use of waxes as modifying agent for filled plastics

p0001The invention relates to the use of waxes as modifying agents for fillers containing thermoplastic or thermosetting plastics containing such waxes.

p0002Fillers generally powdered or fibrous substances organic or inorganic origin are understood, which are dispersed in organic media, dispersions or emulsions, to give the respective final product specific properties or to reduce its cost price. The fillers, inorganic and organic materials to be distinguished. Of particular importance, calcium carbonate, calcium magnesium carbonate, aluminum silicates, silica, magnesium silicates (talc), barium sulfate, aluminum potassium sodium silicates, metals and oxides, Aluminiumhydoxide, carbon blacks and graphite, wood flour and cork flour, wood chips, wood fibers, glass fibers and natural fibers (<nplcit id="ncit0001" npl-type="b"><text>HP Schlumpf, "Filler and Reinforcements" in R. Gächter, H. Müller, Plastic Additives, 3rd Edition, Carl Hanser Verlag Munich 1993, S.525 - 591</text></nplcit>).

p0003Fillers are used in a wide range of applications. Specifically, here are the applications of plastics, paints, coating materials, paper, building materials and adhesives mentioned. Depending on the application various properties of the fillers are relevant. Typical parameters are the refractive index, the binder pickup, the specific surface area, the opacity, the abrasion (wear of the processing equipment), the gloss, the particle shape and the particle size distribution. Particularly in the case of fibrous fillers, the compatibility between the filler and matrix of particular interest. To improve this connection between the two materials such as glass fibers are coated with appropriate substances.

p0004Over the past decades, the importance of fillers increased in plastics processing continuously. While in the past primarily aimed either a cheapening of the final product or the quantitative increase of the finished article in the filling material, is used in the subsequent period from the influence of the fillers on the processing properties and the properties of the finished products. With the help of fillers properties such as processing speed, dimensional stability, flammability, abrasion resistance, the dielectric strength or the mechanical properties were optimized. In the field of plastics processing fillers particularly in polyvinyl chloride, polyethylene, polypropylene and rubber are (natural and synthetic non-crosslinked and crosslinked, for example by vulcanization, elastomers). Engineering thermoplastics (polycarbonate, polymethyl methacrylate, polyamide, polystyrene, etc.) are added only rarely fillers.

p0005For the most diverse applications, wood-filled thermoplastics have established as prior art. Here wood flour, wood fibers or wood chips are incorporated in high concentrations. Are usual in this case filling levels from 50 to 90 wt .-%. As matrix material commercially available thermoplastics are used. In particular, here are polyvinyl chloride, to name a polypropylene and the different types of polyethylene. Less often used engineering thermoplastics such as polystyrene or other styrene polymers (eg, ABS) are used. In addition to said main components, some additives to optimize the properties are used in such applications. Thus small amounts of modified polymers to improve the mechanical properties are added. Unsolved problems are so far the rapid aging of these materials under changing weather conditions and the poor dimensional stability due to the water absorption of the incorporated into the plastic timber.

p0006Surprisingly, it has been found that the addition of waxes to filled plastics provides performance advantages. The use of appropriate products affect the property profile of the moldings clearly positive. There are raised the mechanical characteristics under tensile and bending stress.

p0007Further, the water absorption is retarded and reduced by hydrophilic fillers. At the same time an improved dimensional stability is achieved.

p0008The invention therefore relates to the use of synthetic or natural waxes for modifying the mechanical properties, water resistance and dimensional stability of filled with organic fillers plastics.

p0009It is preferable that in the natural waxes comprise petroleum waxes, montan waxes, animal waxes and / or vegetable waxes.

p0010It is preferable that in the synthetic waxes are fatty acids, fatty acid esters, fatty acid amides, Fischer-Tropsch waxes, polyolefin and / or polar-modified polyolefin waxes.

p0011It is preferable that in the natural waxes are montan waxes. Montan waxes are ester waxes and / or salts of carboxylic acids. There are in particular reaction products of montan wax acids with polyhydric low molecular weight alcohols.

p0012It is preferable that in the natural waxes, for example, plant waxes such as carnauba or candelilla waxes or animal origin such as shellac wax into question. Suitable semisynthetic waxes are, for example, bleached, optionally chemically for example by esterification and / or by partial hydrolysis modified montan waxes. Corresponding products are, for example, in<nplcit id="ncit0002" npl-type="b"><text>Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, Vol A 28, Weinheim 1996 Chapter 2.2, 2.3 and 3.1-3.5, p. 110 -. 126</text></nplcit> described.

p0013Preferred is polar or nonpolar fully synthetic waxes, such as polyolefin. Non-polar polyolefin waxes may be prepared by thermal degradation of branched or unbranched polyolefin plastics or by direct polymerization of olefins. Examples of polymerization join radical procedure in question, which the olefins, generally ethylene, are reacted at high pressures and temperatures to more or less branched waxes; next processes in which ethylene and / or higher 1-olefins with the aid of organometallic catalysts, such as Ziegler-Natta or metallocene catalysts are polymerized to straight or branched waxes. Appropriate methods for the production of olefin homopolymer and copolymer waxes are, for example, in<nplcit id="ncit0003" npl-type="b"><text>Ullmann's Encyclopedia of Industrial Chemistry, 5th Ed., Vol. A 28, Weinheim 1996</text></nplcit> in <nplcit id="ncit0004" npl-type="b"><text>Chapter 6.1.1 / 6.1.2- (high-pressure</text></nplcit>) <nplcit id="ncit0005" npl-type="b"><text>Cape. 6.1.3. (Ziegler-Natta polymerization, polymerization using metallocene catalysts</text></nplcit>) as <nplcit id="ncit0006" npl-type="b"><text>Cape. 6.1.4 (thermal degradation), pp 146-154</text></nplcit> described. Polar polyolefin waxes are formed by appropriate modification of non-polar waxes, for example by oxidation by air or by the grafting of polar olefin monomers, such as α, β-unsaturated carboxylic acids and / or derivatives thereof, such as acrylic acid or maleic anhydride and / or subsituierte and / or unsubstituted styrenes and / or vinyl silanes. Further, polar polyolefin waxes may be prepared by copolymerization of ethylene with polar comonomers, such as vinyl acetate or acrylic acid; continue by oxidative degradation of higher molecular weight, non-waxy ethylene homo- and copolymers. Relevant examples are found in about<nplcit id="ncit0007" npl-type="b"><text>Ullmann's Encyclopedia of Industrial Chemistry, 5th Ed., Vol. A 28, Weinheim 1996, chap. 6.1.5, p 155</text></nplcit>,

p0014Preferably, in the polyolefin homo- and copolymers of various alkenes.

p0015Preferably at The polyolefin homo- and copolymers of ethene and propene.

p0016Preferably at The polyolefin homo- and copolymers prepared on Ziegler or metallocene catalyst contact.

p0017Preferably, in the polyolefin to polar-modified polyolefin waxes.

p0018It is preferable that in the polar-modified polyolefin waxes oxidation products or graft.

p0019It is preferable that in the graft to products made of radically described polyolefin and one or more polar monomers. Preferably, the monomers are maleic anhydride, alkoxy-substituted vinyl silanes and styrenes.

p0020It is preferable that in the graft products with a dropping point from 90 to 170 ° C.

p0021Particularly preferably, in the graft products with a dropping point of 110 to 150 ° C.

p0022It is preferable that in the graft to products having a melt viscosity at 170 ° C from 0.1 to 10,000 mPas.

p0023Particularly preferably, in the graft to products having a melt viscosity at 170 ° C of 1 to 1000 mPas.

p0024It is preferable that in the graft products with a degree of grafting of 0.1 to 20%.

p0025Particularly preferably, in the graft products with a degree of grafting of 2 to 10%.

p0026the waxes are preferably used in an amount of 0.05 to 10 wt .-%, based on the filler, are used.

p0027the waxes are particularly preferred in an amount of 0.5 to 5.0 wt .-%, based on the filler, are used.

p0028Preferably, the fillers are organic fillers.

p0029Preferably, the organic fillers are wood and cork flour, wood chips, wood fibers and natural fibers.

p0030The fillers are preferably present in an amount from 1 to 99 wt .-% based on the total mixture.

p0031the fillers are particularly preferably used in an amount of 50 to 90 wt .-% of the total mixture.

p0032The invention also relates to a thermoplastic or thermosetting plastic containing 1 to 99 wt .-% of a wax-coated with the above-described filler.

p0033Preferably it is a thermoplastic or thermosetting plastic containing 50 to 95 wt .-% of a wax-coated filler.

p0034It is preferable that the thermoplastic vulcanizable (rubber) or thermosetting plastic is polyvinyl chloride, polyethylene-HD (high density), polyethylene-LD (low density), polyethylene LLDPE (linear low density), polypropylene, natural rubber, synthetic rubber, polycarbonate, polymethyl methacrylate, polyamide, styrene polymers and / or blends of different plastics.

p0035For the introduction of the wax in the mixture there are various ways: For example, the wax may be applied in an existing or new process step, as an aqueous dispersion. Furthermore, it is possible to atomize a wax melt and then applied to the filler. In addition, a mixture of filler and wax in a mixer (for example, blade mixer) are homogenized. It is also possible to meter the wax without further premix directly into the processing machine volumetric or gravimetric and thus only there to establish contact between the individual components.

Examples

p0036Commercial wood chips was premixed with different waxes and a commercial polyethylene-HD and then this mixture was compounded on an extruder. The granulated compounds were processed by injection molding to give moldings. These parts were subjected to various tests. In the experiments a common product on the market was included as a comparison. These recipes are marked with B and set the state of the art. Compound A containing 70 wt .-% wood chips and 30 wt .-% HDPE. Compound B containing 1.5 wt .-% of a commercially available additive for wood / polyethylene system and 70 wt .-% wood shavings and 28.5 wt .-% PE-HD. Compound C contains 1.5 wt .-% of a maleic anhydride grafted metallocene polyethylene wax as an additive for the system Wood / polyethylene and 70 wt .-% wood shavings and 28.5 wt .-% PE-HD.

Characterization of the novel additive:

p0037Polyethylene wax prepared by metallocene catalysis<tables id="tabl0001" num="0001"><table frame="none"><tgroup cols="2" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="21mm" /><colspec colnum="2" colname="col2" colwidth="38mm" /><tbody><row><entry>Dropping point:</entry><entry>120 ° C</entry></row><row><entry>Acid number:</entry><entry>about 40 mg KOH / g</entry></row><row><entry>Viscosity:</entry><entry>about 220 mPas at 140 ° C</entry></row></tbody></tgroup></table></tables>

p0038Compound Preparation: All powdered ingredients were homogeneously mixed in a tumble mixer. This mixture was processed with a co-rotating twin-screw extruder to form a granulate.

p0039Prüfköperherstellung: All tests Standard dumbbell specimens were injection molded according to DIN EN ISO 294th

p0040The mechanical properties were determined according to DIN EN ISO 178, DIN EN ISO 179 and DIN EN ISO 527th The study of water absorption was carried out in accordance with DIN EN ISO 62nd<tables id="tabl0002" num="0002"><table frame="all"><tgroup cols="4"><colspec colnum="1" colname="col1" colwidth="57mm" /><colspec colnum="2" colname="col2" colwidth="12mm" /><colspec colnum="3" colname="col3" colwidth="12mm" /><colspec colnum="4" colname="col4" colwidth="12mm" /><thead><row><entry valign="top" /><entry align="center" valign="top">A</entry><entry align="center">B</entry><entry align="center">C</entry></row></thead><tbody><row><entry>Train Modulus [MPa]</entry><entry align="center">5730</entry><entry align="center">5680</entry><entry align="center">6880</entry></row><row><entry>Tensile strength [N / mm²]</entry><entry align="center">25.7</entry><entry align="center">28.2</entry><entry align="center">38.4</entry></row><row><entry>Tensile elongation [%]</entry><entry align="center">0.7</entry><entry align="center">0.7</entry><entry align="center">0.8</entry></row><row><entry>Impact strength [kJ / m²]</entry><entry align="center">2.2</entry><entry align="center">2.9</entry><entry align="center">3.5</entry></row><row><entry>Flexural Modulus [Mpa]</entry><entry align="center">4190</entry><entry align="center">4070</entry><entry align="center">4100</entry></row><row><entry>Flexural strength [N / mm²]</entry><entry align="center">24.4</entry><entry align="center">29.7</entry><entry align="center">40.3</entry></row><row><entry>Bending strain [%]</entry><entry align="center">0.8</entry><entry align="center">0.9</entry><entry align="center">1.2</entry></row><row><entry>Water absorption after 20 days [%]</entry><entry align="center">114</entry><entry align="center">112</entry><entry align="center">107</entry></row><row><entry>Water absorption after 50 days [%]</entry><entry align="center">116</entry><entry align="center">115</entry><entry align="center">113</entry></row></tbody></tgroup></table></tables>

p0041The measured values ​​listed clearly show that the compound C has by far the best properties.