Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Particulate matter
Reexamination Certificate
1997-10-29
2001-05-29
Thibodeau, Paul (Department: 1773)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Particulate matter
C428S407000, C428S363000, C428S451000, C428S454000, C428S500000, C524S442000, C524S582000
Reexamination Certificate
active
06238793
ABSTRACT:
BACKGROUND OF THE INVENTION
This patent application claims priority to Japanese Patent Application No. 8-305510, filed Nov. 1, 1996, which is incorporated herein by reference.
1. Field of Invention
The present invention pertains to a composite material made of a low-density polyethylene and a lamellar silicate, and it further pertains to a composite material with high transparency achieved through the thorough dispersing of a lamellar silicate with a low-density polyethylene produced by inserting a low-density polyethylene between the silicate layers of a lamellar silicate. A film made of the low-density polyethylene-lamellar silicate composite material of the present invention is transparent and has excellent gas-barrier properties, and an injection molding made thereof has greater rigidity while maintaining a glossy surface, and is used effectively for moldings that require both a high-gloss surface and rigidity such as bumpers for vehicles and OA machines.
2. Background
In the past, many attempts have been made to produce a composite material by inserting an organic polymer material between silicate layers that comprise a lamellar silicate. That research is summarized in Chuzo Kato (Polymers, 1970, Vol. 19, No. 222, pp. 758-764), and Chuzo Kato and Kazuyuki Kuroda (Clay Science, 1986, Vol. 26, No. 4, pp. 292-305), etc. However, it has not been possible to increase the distance between layers through insertion of an organic polymer material between the silicate layers or dispersion of a clay mineral, even when the parallelism between layers is reduced.
As a composite material developed to eliminate the above-mentioned problem, a clay mineral/polyamide resin composition produced by polymerization of the silicate layer that forms an expandable clay mineral with an alkylamine expanding agent after performing treatment, as needed, and further impregnating with a monomer is known (Japanese Kokai Patent Application Nos. Sho 58[1983]-35211 and Sho 58[1983]-35542). Also, a composite material produced by mixing a resin containing a polyamide with a silicate layer having a thickness of the silicate layer that forms the lamellar silicate in the range of 7-12 Å (angstroms) and a layer to layer distance of at least 30 Å has been reported (Japanese Kokai Patent Application No. Sho 62[1987]-74957). In manufacturing the above-mentioned composite materials, a polymerization reaction is included in the production process; thus, production is not necessarily easy.
As a material that can be produced without difficulty in the production process, a resin composition containing a composite material produced by hot-melt kneading of a lamellar silicate/alkylamine expanded composite material prepared by first dispersing a low-density polyethylene and an alkylamine expansion agent with a polyamide to increase the distance between layers to at least 30 Å and to reduce the parallelism between layers has been reported (U.S. Pat. No. 5,385,776).
Furthermore, the applicant has developed a method for manufacturing a composite material consisting of dispersing mixing, drying and pulverizing a polar organic polymer material that can be dissolved or dispersed in water and can be hot-melt mixed with a lamellar silicate in order to produce a composite material having good thermostability that can be easily produced and is capable of dispersing a lamellar silicate even when an organic polymer material other than polyamide is used (Japanese Patent Application No. Hei 8[1996]-65355).
As shown, the above-mentioned technologies concern composite materials produced by dispersing a lamellar silicate in a polymer having a polar group in an organic polymer such as a polyamide and an ionomer, and the focus is on composite materials made primarily of a polar polymer. In this case, the low-density polyethylene includes a polar group, thus, affinity with nonpolar polymers is inadequate, and adequate dispersion cannot be achieved; as a result, transparency is lost.
However, in recent years, studies on dispersing a lamellar silicate in a nonpolar polymer have been carried out. For example, as a method for manufacturing a composite material consisting of dispersing montmorillionite in a polymer, a method in which ion-exchange treatment is performed for a sodium montmorillonite with distearyldimetylammonium in water, followed by washing, pulverization and drying to produce an organic montmorillonite, a reaction is performed with an oligomer in an organic solvent having affinity for both the polymer and the montmorillonite, followed by washing and drying, and hot-melt kneading is carried out for the polymer has been reported (Fall of 1995, Polymer Processing Technology Discussion Meeting, Lecture Material, pp. 53-54, Synthesis and Properties of PP Clay Hydrides).
Excellent dispersively can be achieved in the above-mentioned method, but the method involves many steps in the production process and is complex and not practical.
Furthermore, a composite material produced by dispersing a lamellar silicate with a low-density polyethylene used for films, etc. because of softness and transparency and having good processability using a very simple method has not been developed.
3. Problems to be Solved by the Invention
Based on the above background, the objective of the present invention is to produce a composite material by dispersing a lamellar silicate in a low-density polyethylene, which is a type of nonpolar polymer, and to provide a simple method for manufacturing thereof.
SUMMARY OF THE INVENTION
The present invention pertains to a low-density polyethylene-lamellar silicate composite material containing a low-density polyethylene, a lamellar silicate and a surfactant that remains liquid at room temperature; the above-mentioned low-density polyethylene is inserted between the silicate layers of the above-mentioned lamellar silicate.
Furthermore, the present invention is a method for manufacturing a low-density polyethylene-lamellar silicate composite material wherein a master batch is produced having a surfactant that remains liquid at room temperature between the layers of the lamellar silicate, and, subsequently, hot-melt mixing is performed for the above-mentioned master batch and a low-density polyethylene so as to insert the above-mentioned low-density polyethylene between the silicate layers of the above-mentioned lamellar silicate.
The present invention is more fully set forth in Japanese Patent Application No. 8-305510, filed Nov. 1, 1996, and in the remainder of this Specification.
REFERENCES:
patent: 5385776 (1995-01-01), Maxfield et al.
patent: 5747575 (1998-05-01), Nishida et al.
patent: 5883173 (1999-03-01), Elspass et al.
patent: 58-35542 (1983-08-01), None
patent: 58-35211 (1983-08-01), None
patent: 62-74957 (1987-04-01), None
patent: 8-65355 (1996-02-01), None
patent: WO 97/31973 (1997-09-01), None
Chuzo Kato, Complexes of Clay and Organic Polymers,Polymers, 19, No. 222, 758-764, 1970.
Chuzo Kato and Kazuyuki Kuroda, Intercalation Compounds of Clays,Clay Science, 26, No. 4, 292-305, 1986.
Makoto Kato, et al., Synthesis and Properties of Polypropylene-Clay Hybrid,Polymer Processing Technology Discussion Meeting Lecture Material, 53-54, 1995.
Arai Takayuki
Kobayashi Toshikazu
Monma Tsunemi
Takahashi Tatsuhiro
E. I. Du Pont de Nemours and Company
Rickman Holly C.
Thibodeau Paul
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