Stock material or miscellaneous articles – Hollow or container type article – Polymer or resin containing
Patent
1997-02-21
1998-08-18
Gorr, Rachel
Stock material or miscellaneous articles
Hollow or container type article
Polymer or resin containing
428 369, 604 96, 606194, 528 60, 528 76, C08G 1848
Patent
active
057956332
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates to a shaped article and a material composition. More particularly, it relates to a medical shaped article used as parts for which a high stretchability is required, such as a balloon of a catheter, and having a low toxicity, a high tear strength, a high tensile strength, a large elongation and a reduced permanent set, and to a material composition used for the medical shaped article.
2. Background Art
For medical articles used as treating living bodies such as a catheter and an artificial vessel, a low toxicity, a high tear strength, a high tensile strength, a large elongation and a reduced permanent set are required.
As a material used for a shaped article such as a balloon of a catheter, natural rubber is well known. However, it has recently been found that natural rubber contains a trace amount of protein and causes a biological allergic reaction. Therefore a material composition which can be a substitute for natural rubber is eagerly desired.
As a natural rubber substitute, a thermoplastic polyurethane is known. A thermoplastic polyurethane is a polymer prepared by a polycondensation reaction between approximately equimolar amounts of a diisocyanate and a diol or diamine. However, as is known in the art, in the case where a thermoplastic polyurethane is used for a part such as a catheter balloon, for which a 500% or higher elongation is required, when the balloon contracts, it is creased and a blood stream becomes locally stagnant and a salient amount of thrombus is produced. Further, a shaped article made of a thermoplastic polyurethane has a low tensile strength and elongation, as compared with natural rubber, and a large permanent set. Thus a thermoplastic polyurethane cannot be a perfect substitute for natural rubber.
It is conducted that molecule chains of a thermoplastic polyurethane are crosslinked with a cross-linking agent having at least three functional groups or other crosslinkers to reduced the permanent set of the thermoplastic polyurethane. However, the crosslinked thermoplastic polyurethane has a low tensile strength and tear strength, and therefore is not suitable for shaped articles for which high tenacities are required.
DISCLOSURE OF INVENTION
An object of the present invention is to provide a shaped article suitable as parts for which a high stretchability is required, and having a low toxicity, a high tear strength, a high tensile strength, a large elongation and a reduced permanent set, and to a material composition used for the shaped article.
The inventors have conducted researches to achieve the above objects, and found that, when a polyurethane made by using a specific chain extender is used, the above object can be achieved, and completed the present invention.
In accordance with the present invention, there is provided a material composition characterized as comprising, as the essential ingredients: groups capable of being additionally polymerized with an isocyanate group, functional groups capable of being additionally polymerized with an isocyanate group, and three functional groups capable of being additionally polymerized with an isocyanate group; with an isocyanate group, in compounds (c) and (d), is 1 to 35 moles per 100 moles of the isocyanate groups in polyfunctional isocyanate (a), polymerized with an isocyanate group, in compound (d), is 0.1 to 18 moles per 100 moles of the isocyanate groups in polyfunctional isocyanate (a), polymerized with an isocyanate group, in compound (b), is 60 to 100 moles per 100 moles of the isocyanate groups in polyfunctional isocyanate (a), and with an isocyanate group, in compounds (b), (c) and (d), is 80 to 110 moles per 100 moles of the isocyanate groups in polyfunctional isocyanate (a).
In accordance with the present invention, there is further provided a shaped article made of a polymer prepared by additional polymerization of polyfunctional isocyanate (a) with compound (b), compound (c) and compound (d).
BEST MODE FOR CARRYING OUT THE INVENTION
The invention will now be
REFERENCES:
patent: 4156066 (1979-05-01), Gould
patent: 4371686 (1983-02-01), Yamamoto et al.
patent: 5061254 (1991-10-01), Karakelle et al.
patent: 5468834 (1995-11-01), Finsterwalder et al.
Hiraoka Kyoko
Kidokoro Hiroto
Yokoyama Tetsuo
Gorr Rachel
Nippon Zeon Co. Ltd.
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