Patent Application
20090005487
1. Field of the Invention
The present invention relates to a composite material composition comprising an inorganic compound and a resin as well as a molded article comprising the composite material composition.
2. Related Art
Hitherto, in order to improve stiffness of a molded article comprising a thermoplastic resin such as polypropylene, an inorganic filler such as talc is sometimes added to the thermoplastic resin.
However, since an inorganic filler generally has a poor affinity to a thermoplastic resin such as polypropylene, the addition of the inorganic filler invites decrease in impact strength and the like of the molded article.
Thus, as described in JP-A-7-278378, JP-A-2000-143872 and Non-Patent Document: “Journal of Applied Polymer-Science”, 1996, vol. 61, p. 1877-1885, it is known to add a polymer (polypropylene or an elastic body) having a carboxyl group as a modifying group so as to improve affinity of the inorganic filler to the thermoplastic resin.
Nonetheless, it is generally considered that, even when an inorganic filler is added in an amount more than a certain amount, it is not expected to improve stiffness of the molded article any more and also the addition lowers impact strength and the like as well as it is considered that it is difficult to homogeneously mix a large amount of the inorganic filler with a small amount of the resin. Accordingly, there are only described those containing a smaller amount of an inorganic filler (about 1 to 70% by weight, and 5% by weight, 15% by weight, and 30% by weight in Examples) and a larger amount of a resin, in JP-A-7-278378, JP-A-2000-143872 and the Non-Patent Document.
An object of the invention is to provide a composite material composition which secures a high stiffness and also has a sufficient impact strength through increasing a mixing amount of an inorganic compound as well as a molded article comprising the composite material composition.
The composite material composition of the invention comprises 50 to 95% by weight of a micro body of an inorganic compound, 0.1 to 30% by weight of a modified ethylene-butene copolymer rubber that is an unsaturated dicarboxylic acid-modified ethylene-butene copolymer rubber or an unsaturated dicarboxylic acid anhydride-modified ethylene-butene copolymer, and 1 to 48% by weight of a polypropylene resin.
Moreover, the composite material composition of the invention is formed by mixing the above raw material components and preferred is one wherein the micro body of the above inorganic compound is surrounded by a mixture of the above modified ethylene-butene copolymer rubber and the above polypropylene resin.
Furthermore, the composite material composition of the invention may contain an alicyclic hydrocarbon resin, may contain a modified polypropylene resin that is an unsaturated dicarboxylic acid-modified polypropylene resin or an unsaturated dicarboxylic acid anhydride-modified polypropylene resin, may contain both of the above alicyclic hydrocarbon resin and the above modified polypropylene resin, or may not contain both of them.
The molded article of the invention comprises the above composite material composition.
The following will exemplify embodiments of individual elements in the invention.
The inorganic compound is not particularly limited but examples thereof may include natural minerals such as calcium carbonate, talc, mica, wollastonite, silica, and clay. Preferred is at least one of calcium carbonate, talc, mica, and wollastonite. In this connection, the inorganic compound may be not only a natural mineral but also an artificially synthesized one.
The shape of the micro body of the inorganic compound is not particularly limited but examples thereof may include spherical, columnar, needle-like, flake-like ones and the like. The length of the longest part thereof is preferably 90 μm or less, more preferably 50 μm or less.
The amount for modification is not particularly limited but is preferably from 0.5 to 3% by weight. The glass transition temperature (Tg) is not particularly limited but is preferably from −70 to −50° C.
The unsaturated dicarboxylic acid-modified ethylene-butene copolymer rubber is not particularly limited but examples thereof may include maleic acid-modified, itaconic acid-modified ones and the like. Preferred is a maleic acid-modified ethylene-butene copolymer rubber.
The unsaturated dicarboxylic acid anhydride-modified ethylene-butene copolymer rubber is not particularly limited but examples thereof may include maleic anhydride-modified, itaconic anhydride-modified ones and the like. Preferred is a maleic anhydride-modified ethylene-butene copolymer rubber.
Melt flow rate (MFR: at 230° C., 2.16 kgf (21.18N)) is not particularly limited but is preferably from 20 to 150 g/10 minutes in the case of the use as a composite material composition for injection molding and is preferably from 1 to 60 g/10 minutes in the case of the use as a composite material composition for extrusion molding.
The mixing amount of the alicyclic hydrocarbon resin in the case where it is contained in the composite material composition is not particularly limited but is preferably from 0.1 to 20% by weight. Moreover, softening point is not particularly limited but is preferably from 60 to 150° C.
The mixing amount thereof in the case where it is contained in the composite material composition is not particularly limited but is preferably from 0.1 to 10% by weight. Moreover, the amount for modification is not particularly limited but is preferably from 0.5 to 3% by weight. Melting point (Tm) is not particularly limited but is preferably from 150 to 170° C. Melt flow rate (MFR: at 230° C., 2.16 kgf (21.18N)) is not particularly limited but is preferably from 1 to 100 g/10 minutes.
The unsaturated dicarboxylic acid-modified polypropylene resin is not particularly limited but examples thereof may include maleic acid-modified, itaconic acid-modified ones and the like. Preferred is a maleic acid-modified propylene resin.
The unsaturated dicarboxylic acid anhydride-modified polypropylene resin is not particularly limited but examples thereof may include maleic anhydride-modified, itaconic anhydride-modified ones and the like. Preferred is a maleic anhydride-modified propylene resin.
The molded article is not particularly limited but examples thereof may include the following:
instrument panels, pillar trims, center consoles, and the like that are interior products of automobiles;
bumpers, side moldings, and the like that are exterior products of automobiles; and
cases for electronic devices, and the like.
The method of mixing raw material components is not particularly limited but they may be mixed in a so-called batch-wise manner where individual raw material components are measured previously every mixing unit and they are then mixed together or in a so-called continuous manner where individual raw material components are continuously measured and mixed.
The mixing method for the batch-wise manner is not particularly limited but there may be specifically mentioned a method of charging one batch amount of individual raw material components into a Banbury mixer and mixing them.
The mixing method for the continuous manner is not particularly limited but there may be specifically mentioned a method of continuously measuring individual raw material components and feeding them to a molding machine such as an extruder so that the mixing ratio becomes constant every time and mixing them in the cylinder until the blend is discharged from the molding machine.
Moreover, in order to efficiently mix them, it is preferred to heat them at a temperature of 200 to 230° C. during mixing although the temperature is not particularly limited.
The method of molding a molded article comprising the above composite material composition is not particularly limited but examples thereof may include injection molding, extrusion molding, press molding, blow molding, and the like, which are methods used for molding usual resin materials.
Additives such as a plasticizer, an antiaging agent, a colorant, a dispersant, and a flame retardant can be mixed with the composite material composition unless they impair the object of the invention.
According to the invention, there can be provided a composite material composition which secures a high-stiffness and also has a sufficient impact strength through increasing a mixing amount of an inorganic compound as well as a molded article comprising the composite material composition.
The invention provides a composite material composition comprising 50 to 95% by weight of a micro body of an inorganic compound, 0.1 to 30% by weight of a modified ethylene-butene copolymer rubber, and 1 to 48% by weight of a polypropylene resin.
The composite material composition of the invention comprises a micro body of an inorganic compound, a modified ethylene-butene copolymer rubber, and a polypropylene resin, wherein, as shown in
As Examples of the invention, test pieces for evaluation were prepared with 12 kinds of mixings shown in the following Table 1 and were evaluated. Moreover, test pieces for evaluation as Comparative Examples were prepared with 4 kinds of mixings and were also evaluated. In this connection, the unit of the mixing amount of each raw material component in the columns of the mixing content in Table 1 is “% by weight”.
As the raw material components used in Examples and Comparative Examples, trade name “calcium carbonate heavy” of Maruo Calcium Co., Ltd. was used as calcium carbonate, trade name “LS 100” of Fuji Talc Kogyosho K.K. as talc, trade name “NYGLOS M15” of NYCO MINERAL, INC. as wollastonite, and trade name “B-82” of Yamaguchi Mica Co., Ltd. as mica.
Trade name “Toughmer MH7007” of Mitsui Chemicals Inc. was used as a maleic anhydride-modified ethylene-butene copolymer rubber, trade name “PPMA6252” of Clariant Japan K.K. as a maleic anhydride-modified polypropylene resin, and trade name “Toughmer MP0620” of Mitsui Chemicals Inc. as a maleic anhydride-modified ethylene-propylene copolymer rubber.
Trade name “BC06C” (MFR: 60 g/10 minutes at 230° C., 2.16 kgf (21.18N)) of Japan Polypropylene Corp. was used as a polypropylene resin and trade name “Arkon P70” of Arakawa Chemical Industries, Inc. as an alicyclic hydrocarbon resin.
A test piece to be used in each evaluation was mixed and molded as follows.
Using a 80-tons injection molding machine where temperature of the cylinder was set at 230° C., individual raw material components were measured and charged from a hopper located at a terminal edge of the cylinder so that the mixing ratio became constant each time and, after they were mixed by rotating screws in the cylinder, the mixed product was injected into a mold heated at a mold temperature of 40° C., thereby molding being effected.
In order to measure bending modulus, a test was conducted in accordance with ISO-178.
In order to measure IZOD impact strength, a test was conducted in accordance with ISO 180.
Under the above molding conditions, a square test piece having a thickness of 2 mm and a side length of 70 mm was molded and surface conditions of the test piece was visually observed and evaluated.
As evaluation results, ◯ represents good appearance and x represents bad appearance.
Residential stability, flowability, and the like of each sample at molding were evaluated in the case where molding was conducted under the above conditions.
As evaluation results, ◯ represents the case where molding is achieved without any problems on residential stability, flowability, and the like, and x shows the case where problem(s) such as insufficient flowability, bad metering, and/or the like arise.
From the above results, the molded articles of the present Examples secure a high stiffness and also have a sufficient impact strength. Moreover, injection molding can be achieved without troubles and also appearance of the molded articles is good. The results are attributable to the following reasons:
the high stiffness is attributable to the use of an inorganic compound as a matrix (high filling);
the high impact strength is attributable to the fact that, when stress is imparted, a mixture of the modified ethylene-butene copolymer rubber and the polypropylene resin and the like relieves the stress; and
the good moldability is attributable to the fact that the modified ethylene-butene copolymer rubber and the like in the mixture of the modified ethylene-butene copolymer rubber and the polypropylene resin and the like increases affinity of the micro body of the inorganic compound to the mixture and hence the polypropylene resin and the like in the mixture slides the micro body of the inorganic compound.
Furthermore, by incorporating a larger amount of the inorganic compound, a product having a high dimensional stability (ultra-low linear expansion) was formed.
Incidentally, the invention is not limited to the above. Examples and can be specified with suitably changing them without departing from the gist of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-169774 | Jun 2007 | JP | national |
