Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2002-07-12
2003-10-14
Nutter, Nathan M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S216000, C525S221000, C525S222000, C525S232000, C525S240000, C428S500000, C428S515000, C428S516000, C428S520000, C428S523000
Reexamination Certificate
active
06632885
ABSTRACT:
TECHNICAL FIELD
The present invention relates to soft syndiotactic polypropylene compositions, and more particularly to soft syndiotactic polypropylene compositions having a good balance among transparency, flexibility and heat resistance and molded products comprising the compositions.
BACKGROUND ART
Films comprising isotactic polypropylene obtained by copolymerizing propylene, ethylene and optionally an &agr;-olefin of 4 to 20 carbon atoms are widely employed for various packaging materials because they are inexpensive and have excellent flexibility, moisture resistance and heat resistance. However, if the film thickness is increased in order to prevent damage of the contents, transparency, flexibility and heat sealing properties of the film become poor. If the comonomer content in the isotactic polypropylene is increased in order to improve these properties, the tacky component increases to cause lowering of blocking resistance. Therefore, it is difficult to produce packaging materials of excellent transparency, flexibility and heat sealing properties from films of large thickness.
It is known that the syndiotactic polypropylene is obtained by low-temperature polymerization in the presence of a catalyst comprising a vanadium compound, ether and organoaluminum. The polymer obtained by this process, however, has low syndiotacticity and does not possess such elastic properties as the syndiotactic polypropylene inherently has.
Recently, it has been discovered by J. A. Ewen, et al. that high-tacticity polypropylene having a syndiotactic triad fraction of more than 0.7 is obtained in the presence of a catalyst comprising a transition metal catalyst having an asymmetric ligand and aluminoxane (see J. A. Chem. Soc., 1988, 110, 6255-6256). The polymer obtained by the process of J. A. Ewen, et al. has a high syndiotacticity and shows more elastic properties than the isotactic polypropylene. However, if the polymer is used as a soft molding material in, for example, a field where non-rigid vinyl chloride or a vulcanized rubber is used, the polymer is not satisfactory in its flexibility, elastomeric properties and mechanical strength.
Thus far, attempts to improve flexibility and impact resistance of propylene-based polymers have been made by adding thereto ethylene/propylene copolymer rubbers in which the stereoregularity of propylene units is isotactic, but molded products comprising a resin composition obtained by this process do not have sufficient flexibility and impact resistance though these properties have been improved to a certain extent.
Further, the syndiotactic polypropylene has a low crystallizing rate and thereby has a problem of winding round a take-up roll in the T-die film molding, and therefore improvement of the crystallizing rate has been desired.
Under such circumstances as described above, the present inventors have made earnest studies, and as a result, they have found that a soft syndiotactic polypropylene composition (1) comprising a specific syndiotactic propylene polymer, an &agr;-olefin polymer, and a crystal nucleating agent and/or an ethylene-based polymer has a good balance among transparency, flexibility, heat resistance and scratch resistance.
The present inventors have further found that a soft syndiotactic polypropylene composition (2) comprising a specific syndiotactic propylene polymer, an &agr;-olefin polymer, an isotactic propylene polymer, and a crystal nucleating agent and/or an ethylene-based polymer has a good balance among transparency, flexibility, heat resistance and scratch resistance, particularly a soft syndiotactic polypropylene composition (2) comprising a specific syndiotactic propylene polymer, an &agr;-olefin polymer, an isotactic propylene polymer and an ethylene-based polymer has a good balance among transparency, flexibility, heat resistance and scratch resistance and shows excellent moldability.
The present inventors have furthermore found that a soft syndiotactic polypropylene composition (3) comprising a specific syndiotactic propylene polymer, an &agr;-olefin polymer, an ethylene-based polymer, an isotactic propylene polymer and a copolymer of polar group-containing vinyl and ethylene has a good balance among transparency, flexibility, heat resistance and impact resistance and shows excellent moldability, and that films obtained from the composition have excellent tearability.
Moreover, the present inventors have found that a laminate having a layer of a thermoplastic resin and a layer of any one of the syndiotactic polypropylene compositions (1) to (3) have various useful properties. Based on the finding, the present invention has been accomplished.
DISCLOSURE OF THE INVENTION
The soft syndiotactic polypropylene composition (1) of the invention is a composition comprising:
(A) a syndiotactic propylene polymer which comprises recurring units (U
pr
) derived from propylene having a substantially syndiotactic structure, and optionally, recurring units (U
et
) derived from ethylene and/or recurring units (U
ol
) derived-from an &agr;-olefin of 4 to 20 carbon atoms, contains the recurring units (U
pr
) in amounts of 90 to 100% by mol, the recurring units (U
et
) in amounts of 0 to 10% by mol and the recurring units (U
ol
) in amounts of 0 to 9.5% by mol, and has an intrinsic viscosity (&eegr;), as measured in decalin at 135° C., of 0.5 to 10 dl/g,
(B) an &agr;-olefin polymer which comprises at least one kind of recurring units derived from an &agr;-olefin selected from &agr;-olefins of 2 to 20 carbon atoms, contains one kind of recurring units out of said one or more kinds of recurring units in amounts of 50 to 100% by mol, and has a Young's modulus of not more than 150 MPa, and optionally,
(C) a crystal nucleating agent and/or (D) an ethylene-based polymer having a density of 0.91 to 0.97 g/cm
3
,
wherein the weight ratio (A/B) of the syndiotactic propylene polymer (A) to the &agr;-olefin polymer (B) is in the range of 90/10 to 10/90.
The soft syndiotactic polypropylene composition (1) is, in an embodiment, a composition comprising the syndiotactic propylene polymer (A), the &agr;-olefin polymer (B) and the crystal nucleating agent (C), wherein:
the weight ratio (A/B) of the polymer (A) to the polymer (B) is in the range of 90/10 to 10/90, and
the crystal nucleating agent (C) is contained in an amount of 0.01 to 1 part by weight based on 100 parts by weight of the total of the polymer (A) and the polymer (B).
In this soft syndiotactic polypropylene composition,
the syndiotactic propylene polymer (A) preferably has a syndiotacticity, that is based on triad sequences of the propylene units, of not less than 0.6,
the &agr;-olefin polymer (B) preferably has an intrinsic viscosity (&eegr;), as measured in decalin at 135° C., of 0.01 to 10 dl/g, a molecular weight distribution (Mw/Mn), as determined by gel permeation chromatography (GPC), of not more than 4 and a glass transition temperature (Tg) of not higher than −5° C., and
the crystal nucleating agent (C) is preferably a sorbitol type crystal nucleating agent.
The soft syndiotactic polypropylene composition has a good balance among transparency, flexibility, heat resistance and scratch resistance.
The soft syndiotactic polypropylene composition is, in another embodiment, a composition comprising the syndiotactic propylene polymer (A) and two or more kinds of the &agr;-olefin polymers (B), wherein:
the weight ratio (A/(total of B)) of the polymer (A) to the total of the two or more kinds of the polymers (B) is in the range of 90/10 to 10/90, and
each content of the two or more kinds of the polymers (B) is at least 1% by weight.
This soft syndiotactic polypropylene composition is preferably a composition further comprising the crystal nucleating agent (C), wherein:
the weight ratio (A/(total of B)) of the polymer (A) to the total of the two or more kinds of the polymers (B) is in the range of 90/10 to 10/90,
each content of the two or more kinds of the polymers (B) is at least 1% by weight, and
the crystal nucleating agent (C) is contained in an amount of 0.01 to 1 part
Kaneko Kazuyoshi
Mori Ryoji
Morizono Kenichi
Burns Doane , Swecker, Mathis LLP
Mitsui Chemicals Inc.
Nutter Nathan M.
LandOfFree
Soft syndiotactic polypropylene composition and molded product does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Soft syndiotactic polypropylene composition and molded product, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Soft syndiotactic polypropylene composition and molded product will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3157119