Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-10-09
2003-11-18
Yoon, Tae H. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S847000, C524S504000, C525S064000
Reexamination Certificate
active
06649685
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a long fiber-reinforced polypropylene resin composition which is suited for producing not only small-sized molded articles but also wide-ranged molded articles extending from medium-sized ones to large-sized ones and to a molded article obtained from the same. Specifically, it relates to a molded article which is excellent in a mechanical strength, particularly a mechanical strength in a direction perpendicular to a flow direction of the resin obtained especially when it is molded into a medium-sized to large-sized molded article and therefore has a small anisotropy in a mechanical strength and which is excellent as well in an impact strength and to a long fiber-reinforced polypropylene resin composition which provides the same.
BACKGROUND ART
A so-called long fiber-reinforced polypropylene resin composition obtained by impregnating a reinforcing continuous fiber bundle with a molten polypropylene resin and then pultruding it to pelletize to a length of 2 to 50 mm provides a molded article which is excellent in a mechanical strength and an impact resistance and therefore is widely used for uses in car parts, industrial parts and the like.
However, when molding a long fiber-reinforced polypropylene resin composition into medium-sized to large-sized molded articles, the mechanical strength is still unsatisfactory, and particularly the mechanical strength in a direction perpendicular to a flow direction of the resin is short. Accordingly, the molded articles have a large anisotropy in a strength, and it is the existing state that the uses thereof are restricted.
Proposed in U.S. Pat. No. 2,883,369 official gazette (Japanese Patent Application Laid-Open No. 121146/1991) as a long fiber-reinforced resin composition which is improved in a mechanical strength and an impact resistance is a long fiber-reinforced polypropylene resin composition prepared by feeding a molten mixture of a resin component comprising 98 to 50 parts by weight of a polyolefin (A) and 2 to 50 parts by weight of a modified olefin base polymer (B) modified by graft-polymerizing an olefin base polymer comprising propylene as a principal polymer structural unit with maleic anhydride from an extruding machine to a crosshead die to impregnate reinforcing continuous fibers with it. Further, it is described in the above official gazette that capable of being employed as another impregnating method is a method in which a mixture prepared by melting and kneading the polyolefin (A) and an unsaturated carboxylic acid or a derivative thereof together with an organic peroxide is used to impregnate fibers therewith and in which a part of the polyolefin (A) is reacted with an unsaturated carboxylic acid or a derivative thereof to synthesize the modified olefin base polymer (B), whereby the desired resin composition is prepared. However, investigations made by the present inventors have resulted in finding that when the composition described above is molded into a small-sized molded article, the molded article is improved in a mechanical strength and an impact strength, but when it is molded into medium-sized to large-sized molded articles, the mechanical strength and the impact strength, particularly the mechanical strength in a direction perpendicular to a flow direction of the resin are still unsatisfactory as compared with those of conventional ones.
As described above, not yet known is a long fiber-reinforced polypropylene resin composition providing a molded article which is excellent in a mechanical strength and an impact resistance even when it is molded into medium-sized to large-sized molded articles and which is improved particularly in a mechanical strength in a direction perpendicular to a flow direction of the resin and therefore has a small anisotropy in a strength. Thus, such composition has been demanded.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a long fiber-reinforced polypropylene resin composition which can solve entirely the inconveniences described above, that is, an anisotropy in a mechanical strength, an impact resistance and a strength even when it is molded into medium-sized to large-sized molded articles and which can suitably be used as well for uses in medium-sized to large-sized molded articles. Another object is to provide a molded article obtained from the same.
Intensive investigations have been repeated by the present inventors in order to obtain a long fiber-reinforced polypropylene resin composition which can solve the inconveniences described above. As a result thereof, they have found that very useful for solving the problems described above is a long fiber-reinforced polypropylene resin composition in which a matrix polymer comprises a modified propylene homopolymer having a specific isotactic pentad ratio, a specific melt flow rate and a specific Mw/Mn (Q value) in the whole amount, and they have completed the present invention based on this finding.
That is, the present invention comprises structures shown below.
(1) A long fiber-reinforced polypropylene resin composition (A) comprising 35 to 75% by weight of a matrix polymer comprising a modified propylene homopolymer (A1) which is prepared by modifying a propylene homopolymer with an unsaturated carboxylic acid or a derivative thereof and which has an isotactic pentad ratio (P value) of 96% or more, a melt flow rate (230° C., 21.18N) of 80 g/10 min or more and an Mw/Mn (Q value) of 3.5 or less and 25 to 65% by weight of a glass long fiber (A2) having a length of 2 to 50 mm.
(2) A long fiber-reinforced polypropylene resin composition prepared by compounding the long fiber-reinforced polypropylene resin composition (A) as described in the above item (1) and a propylene homopolymer and/or propylene base block copolymer (B).
(3) A molded article obtained by molding the long fiber-reinforced polypropylene resin composition (A) as described in any of the above items (1) to (2).
EMBODIMENT OF THE INVENTION
The propylene homopolymer (A1) modified with an unsaturated carboxylic acid or a derivative thereof which is the matrix polymer constituting the long fiber-reinforced polypropylene resin composition (A) of the present invention, a so-called modified propylene homopolymer has to have an isotactic pentad ratio of 96% or more, a melt flow rate (230° C., 21.18N; hereinafter abbreviated as MFR) of 80 g/10 min or more and a weight average molecular weight
umber average molecular weight (Mw/Mn ; so-called Q value) of 3.5 or less.
In this case, the isotactic pentad ratio shows an isotactic pentad ratio in terms of a pentad unit in a molecular chain and can be determined by means of a
13
C-NMR based on Macromolecules 8 687 (1975). The respective average molecular weights in Mw and Mn can be determined by means of GPC (gel permeation chromatography).
A production process for the above modified propylene homopolymer includes a process in which 100 parts by weight of a propylene homopolymer having an isotactic pentad ratio of 96% or more is molten and kneaded with 0.1 to 5 parts by weight of an unsaturated carboxylic acid or a derivative thereof and 0.01 to 0.5 part by weight of an organic peroxide. A blending amount of the organic peroxide has to be suitably controlled so that the MFR and the Q value fall in the ranges described above.
In addition thereto, any of the following processes may be used as long as the isotactic pentad ratio, the MFR and the Q value fall finally in the ranges of the present invention.
(1) Molten and kneaded are 100 parts by weight of a propylene homopolymer having an isotactic pentad ratio of 96% or more, an MFR of 80 g/10 min or more and a Q value of 3.5 or less and 1 to 10 parts by weight of a commercial modified propylene polymer into which 1 to 10% by weight of an unsaturated carboxylic acid or an anhydride thereof is introduced.
(2) Molten and kneaded are 100 parts by weight of a propylene homopolymer having an isotactic pentad ratio of 96% or more, 1 to 10 parts by weight of a commercial modified propylene polymer into which 1 to 1
Atsumi Nobukazu
Ishiwa Hideshi
Nakai Toshimori
Saito Koichi
Chisso Corporation
J.C. Patents
Yoon Tae H.
LandOfFree
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