Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
2003-05-12
2004-02-10
Edwards, N. (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C426S394000
Reexamination Certificate
active
06689462
ABSTRACT:
TECHNICAL FIELD
The present invention relates to high-strength polyethylene fibres which can be used in a wide range of fields, as various ropes, fishing lines, netting and sheeting for engineering, construction and the like, cloth and nonwoven cloth for chemical filters and separators, sportswear and protective clothing such as bulletproof vests, or as reinforcing material for composites for sport, impact-resistant composites and helmets, and particularly as various industrial materials used at from extremely low temperatures to room temperature; where the performance of said fibres, particularly the mechanical properties such as strength and elastic modulus, undergo little variation with temperature during use in environments subject to large changes in temperature; and the present invention relates to a method for producing said fibres sufficiently quickly industrially.
BACKGROUND TECHNOLOGY
In recent years, active attempts have been made to obtain high-strength, high-elastic modulus fibres from ultrahigh molecular weight polyethylene starting material, and extremely high strength/elastic modulus fibres have been reported. For example, Japanese Unexamined Patent Application S56-15408 discloses a technique known as the “gel spinning method”, where gel-like fibres obtained by dissolving ultrahigh molecular weight polyethylene in solvent are drawn to a high draw ratio.
It is known that the high strength polyethylene fibres obtained by the “gel spinning method” are very high in strength and elastic modulus as organic fibres, and are also highly superior in terms of impact resistance, and these fibres are being evermore widely used in various fields. The abovementioned Japanese Unexamined Patent Application No. S56-15408 discloses that it is possible to provide a material having extremely high strength and elastic modulus, in order to obtain such high strength fibres. However, it is known that high strength polyethylene fibres undergo major changes in performance with temperature. For example, measuring the tensile strength while varying the temperature from about −160° C. reveals a gradual decrease as the temperature increases, and that decrease in performance is particularly marked at from −120° C. to around −100° C. With regard to temperature-related performance, then, it is anticipated that the performance of conventional high-strength polyethylene fibres could be considerably improved if their physical properties at extremely low temperatures could be maintained at room temperature.
Conventional attempts to control changes in the mechanical properties of high-strength polyethylene fibres due to changes in temperature include an attempt to improve the vibration absorption at temperatures not greater than −100° C. (referred to as the extremely low temperature region) by using a suitable ultrahigh molecular weight polyethylene starting material of a specific molecular weight and keeping the molecular weight of the resulting fibres within a suitable range, as disclosed in Japanese Unexamined Patent Application No. H7-166414, but, fundamentally, that technique increases the mechanical dispersion at extremely low temperature. Specifically, it attempts to increase the variation in elastic modulus, whereas the present invention aims to lessen the deterioration in mechanical properties.
Japanese Unexamined Patent Application Nos. H1-156508 and H1-162816 disclose attempts to reduce the creep in high-strength polyethylene fibres by means such as ultraviolet irradiation and peroxides, in the abovementioned gel spinning method. It is noted that, fundamentally, this does decrease the mechanical dispersion in &ggr; dispersion as described above, which is described in the present invention as desirable, but both inventions aim to improve the creep of high-strength polyethylene fibres, but do not decrease the variation in mechanical properties due to changes in temperature. Specifically, if the relaxation strength in the &ggr; dispersion is smaller, the temperature at which the relaxation occurs is usually shifted higher, and so as it is desirable in the present invention to decrease the variation in mechanical properties that occur on changes in temperature, that is, to shift the &ggr; dispersion temperature to a lower temperature, the conventional methods are contrary to the aim of the present invention.
Specifically, it is suggested that having a small &ggr; dispersion value for &ggr; dispersion temperatures in the range no greater than −100° C., as relaxation strength, while keeping the temperature region therefor at very low temperatures allows the good physical properties (especially strength) seen in the very low temperature region to be maintained without relaxation even for long periods at temperatures around room temperature, and such fibres would be extremely useful industrially. Fibres having such novel properties could, as described below, be substituted for conventional high-strength polyethylene fibres with no loss of the fundamental merits which said conventional fibres should have; moreover, as they are high-strength fibres, it is anticipated that they could also be drawn at extremely high speed during production processes and particularly during drawing processes. That is to say, this also has industrial significance as a novel production method which can yield high-strength polyethylene fibres of excellent performance at higher productivity.
In view of the situation described above, the present invention aims to provide high-strength polyethylene fibres characterized in that they have excellent mechanical properties at normal temperatures, and in that the mechanical properties such as strength and elasticity modulus seen on wide temperature variation, particularly in the liquid nitrogen temperature region, are maintained at a high level even at room temperature; and a novel production method therefor.
DISCLOSURE OF THE INVENTION
The first invention of the present invention provides high-strength polyethylene fibres characterized in that they are polyethylene fibres comprising mainly ethylene component having an intrinsic viscosity [&eegr;], when fibrous, of no less than 5, and have a strength of no less than 20 g/d and an elasticity modulus of no less than 500 g/d, and, in the measurement of the temperature variance of the dynamic viscoelasticity of the fibres, the &ggr; dispersion loss modulus peak temperature is no greater than −110° C. and the loss tangent (tan &dgr;) is no greater than 0.03.
The second invention of the present invention provides high-strength polyethylene fibers, characterized in that, in the measurement of the temperature variance of the dynamic viscoelasticity of the fibers, the &ggr; dispersion loss modulus peak temperature is no greater than −115° C.
The third invention of the present invention provides high-strength polyethylene fibers, characterized in that, in the measurement of the temperature variance of the dynamic viscoelasticity of the fibers, the &ggr; dispersion loss tangent (tan &dgr;) is no greater than 0.02.
The fourth invention of the present invention provides high-strength polyethylene fibers, characterized in that, in the measurement of the temperature variance of the dynamic viscoelasticity of the fibers, the crystalline &agr; dispersion loss modulus peak temperature is no less than 100° C.
The fifth invention of the present invention provides high-strength polyethylene fibers, characterized in that, in the measurement of the temperature variance of the dynamic viscoelasticity of the fibers, the crystalline &agr; dispersion loss modulus peak temperature is no less than 105° C.
The sixth invention of the present invention provides high-strength polyethylene fibers, characterized in that they have a strength of no less than 25 g/d and an elasticity modulus of no less than 800 g/d.
The seventh invention of the present invention provides high-strength polyethylene fibers, characterized in that they have a strength of no less than 35 g/d and an elasticity modulus of no less than 120
Ohta Yasuo
Sakamoto Godo
DSM N.V.
Edwards N.
Pillsbury & Winthrop LLP
LandOfFree
Process of making high-strength polyethylene fibers does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process of making high-strength polyethylene fibers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process of making high-strength polyethylene fibers will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3294093