Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Patent
1996-11-01
1998-10-20
Cain, Edward J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
525273, 525321, 5253338, 525387, C08F21000
Patent
active
058247599
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a propylene resin composition with excellent low-temperature flowability, stampable moldability, peeling strength and embossing ability, which is suitably used in the fields of interior materials including, particularly, automobile parts, electrical and electronic parts, ships, wheeled vehicles, buildings, etc., and to a molded article obtained by using the same.
BACKGROUND ART
Hot stampable molding methods are used to obtain molded articles by directly stamping semi-melt sheets which have been extruded from a die of a sheet molding machine, and they are also applied to laminates. Such molding methods are also advantageous from a cost viewpoint since they do not require reheating of once-solidified master sheets, as has been required in conventional molding methods, and such molding methods have therefore been attractive in recent years. As resins suited for this molding method there have been proposed, for example, a propylene resin having a high flowability (Japanese Patent laid-open No.2-80218, etc.) and an olefin thermoplastic elastomers (Japanese Patent laid-open No. 4-73112, No.4-73142, etc.).
However, since all of the above-mentioned resins have a high crystallization rate, they begin to solidify immediately after extrusion from a die and thus provide insufficient flowability. Therefore, it has not been considered that they are suitable for hot stampable molding. The flexibility of the molded article being obtained thus is also inferior. In order to improve it and impart a high flowability, for example, it has been proposed to add 50% by weight of oil, but it has caused the problem of bleed-out of oil from the surface of the molded article, thus notably impairing appearance thereof.
Further, as a result of research, the present inventors found that when visbreaking treatment was conducted using an organic peroxide for the above-mentioned olefin thermoplastic elastomers to impart a high flowability, new problems occurred that the rubber component became crosslinked, forming gel fish-eyes and a nonuniform flowability, and thus resulting in an inferior appearance and a low mechanical strength of the molded article. Also in laminates, another problem occurred that when the above-mentioned resin was used, an adhesive strength for a substrate was low.
Furthermore, such laminates are often subjected to unevenness treatment, i.e., so-called "embossing" for a surface thereof in order to provide the impression of high quality, but the problem occurred that embossing ability was inferior in the above-mentioned resin.
DISCLOSURE OF THE INVENTION
In light of these circumstances, an object of the present invention is to provide a propylene resin composition with a high crystallization rate, excellent low-temperature flowability, flexibility and stampable moldability, and a favorable appearance and a mechanical strength (particularly, tensile elongation), and a molded article using the same, and particularly a multilayered laminate using the above-mentioned composition having superior peeling strength and superior embossing ability.
As a result of extensive study, the present inventors have found that the above-mentioned object can be attained by using a propylene-.alpha.-olefin block copolymer having particular properties, and established the present invention bases on this finding.
That is, the present invention provides a propylene resin composition obtained by dynamic heat treatment of a blend of wherein a ratio (.eta..sub.1 /.eta..sub.2) of melt viscosity .eta..sub.1 at a shear rate of 10.sup.1 sec.sup.-1 to melt viscosity 72 .sub.2 at a shear rate of 10.sup.2 sec.sup.-1 is 3.5 to 8 as measured by a slit die method and flow rate (measured according to JIS K7210, at a temperature of 230.degree. C. under a load of 2.16 kg) adjusted to 50 to 300 g/10 minutes, a main endothermic peak temperature Tmp of 120.degree. to 150.degree. C. for melting temperature and a main exothermic peak temperature Tcp of 85.degree. to 105.degree. C. for crystallization temperatu
Nakagami Sakuyoshi
Saihata Meiko
Watanabe Kazuyuki
Cain Edward J.
Showa Denko K.K.
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