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...
Patent
1991-06-17
1993-10-19
Michl, Paul R.
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...
524451, 525240, 428216, 428218, 428516, 26421112, 264230, C08J 518, C08L 2320, B32B 2708
Patent
active
052546179
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention is directed to a resin composition for producing a film, and a method for producing a film by using said resin composition. More particularly, this invention relates to a resin composition which may be formed into a film having excellent strength, water resistance and folding properties as well as texture and rigidity comparable to those of papers. This invention is also directed to a method for producing a film from said resin composition.
BACKGROUND ART
Papers, polyethylene films, polypropylene films and other polyolefin films have been used as wrapping materials Recently, polyolefins, in particular, are often used for wrapping purposes since they have excellent formability, and the films formed have excellent strength and water resistance.
Papers, however, are still used for wrapping high-class commodities since paper-wrapped commodities give higher-grade appearance. In view of such a situation, there is a demand for a paper like polyolefin film provided with excellent strength, water resistance and formability comparable to those of polyolefin films as well as texture and rigidity comparable to those of papers. For example, there is proposed in Japanese Patent Publication No. 46-41463, a paper-like polyolefin film comprising a high-density polyethylene and/or a polypropylene having calcium carbonate, talc, and other inorganic fillers added thereto.
This prior art paper-like polyolefin film was inferior in its strength, rigidity and formability compared to polyolefin films in spite of its paper-like appearance and texture.
An object of the present invention is to provide a resin composition which may be formed into a film having excellent strength, water resistance and formability inherent to the polyolefin films together with texture and rigidity comparable to those of papers. Another object of the present invention is to provide a preferable method for producing a film by using said resin composition.
DISCLOSURE OF THE INVENTION
To obviate the problems as described above, there is provided by the present invention a resin composition for producing a film comprising
(A) 35 to 87 parts by weight of a high-density polyethylene having melt flow rate at 190.degree. C. of 0.01 to 0.1 g/10 min., density of 0.938 to 0.965 g/cm.sup.3, and melt tension of at least 10 g;
(B) 3 to 25 parts by weight of a propylene-based polymer having melt flow rate at 230.degree. C. of 0.3 to 10 g/10 min.;
(C) 10 to 45 parts by weight of talc;
(D) 1 to 10 parts by weight per 100 parts by weight of (A), (B) and (C) of CaO and/or MgO; and
(E) 0.05 to 1 part by weight per 100 parts by weight of (A), (B) and (C) of a surface active agent;
wherein (C)/(B) is from 2 to 4.
According to the present invention, there is also provided a method for suitably producing a film from said resin composition wherein the film is produced by blown-film extrusion (inflation technique). This method is characterized in that the extrusion is carried out under the conditions wherein ratio R.sub.A /R.sub.E of R.sub.A, which is diameter of the bubble farther than the frost line, to R.sub.E, which is minimum diameter of the bubble between the dye outlet and the frost line, is between 2 and 6, and wherein C, which is length of the bubble in machine direction between the dye outlet and the frost line of the bubble wherein the bubble has a diameter of from 0.8 to 1.5 folds of the dye diameter, is 2 to 15 times larger than R.sub.D, which is the die diameter.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view illustrating the process of the present invention wherein a film is produced by blown-film extrusion using the resin composition of the present invention; and
FIG. 2 is an enlarged schematic view illustrating the characteristic features of the present process.
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention is hereinafter described in detail.
The high-density polyethylene, which may be used for component (A) of the resin composition for producing a film of the present invention (hereinafte
REFERENCES:
patent: 4234469 (1980-11-01), Ohta et al.
patent: 4354004 (1982-10-01), Hughes et al.
patent: 4828906 (1989-05-01), Nishimura et al.
patent: 4866117 (1989-09-01), Egashira et al.
Inoue Hiroshi
Matsunaga Takashi
Nishimura Toshihiro
Asinovsky Olga
Michl Paul R.
Mitsui Petrochemical Industries Ltd.
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