Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2002-06-03
2004-03-30
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S021000, C524S023000
Reexamination Certificate
active
06713537
ABSTRACT:
TECHNICAL FIELD
This invention relates to a regenerated fiber. More particularly, it relates to a regenerated collagen fiber with excellent heat resistance, which can suitably be used for human hair or fur, or as thread to be wound by hand.
BACKGROUND ART
Among the protein fibers, the regenerated collagen fiber exhibits a high mechanical strength like silk; and, thus, has been used in various fields. Particularly, the regenerated collagen fiber is a protein fiber maintaining a characteristic molecular structure derived from collagen and, thus, is close in drape, luster and feel to the human hair that is a natural protein fiber having complex fine structure. Such being the case, there have been attempts to use the regenerated collagen fiber as a replacement for human hair or in an animal hair-like fiber such as a fur (for example, see Japanese Patent Laid-Open No. 168628/1998 and Japanese Patent Laid-Open No. 168629/1998).
In general, the skin or bone of an animal is used as a raw material for the regenerated collagen fiber. The regenerated collagen fiber can be produced by treating these raw materials with an alkali or an enzyme to obtain a water-soluble collagen, followed by extruding and spinning the water-soluble collagen in an aqueous solution of an inorganic salt. Since the regenerated collagen fiber thus obtained is soluble in water, some treatments are applied thereto in order to impart resistance to water to the collagen fiber. As a method for making the regenerated collagen fiber insoluble in water, there are known methods including treating the water-soluble collagen fiber with an aldehyde compound such as formaldehyde or glutaric aldehyde; treating the water-soluble collagen fiber with metal salts such as various chromium salts, aluminum salts or zirconium salts; treating the water-soluble collagen fiber with an epoxy compound; and treating the regenerated collagen fiber with a combination of the above-described methods (for example, Japanese Patent Laid-Open No. 173161/1994).
However, being produced from collagen, the fiber produced by these methods has a lower heat resistance than that of human hair or animal hair containing keratin as a major component, and is susceptible to thermal damages (contraction in length, curling or hardening of hair tips) upon styling with a hair iron or dryer, thus rendering such styling unsatisfactory in view of its inherent properties (the term “styling” as used herein means to impart a desired form to human hair by thermal treatment in a beauty parlor or at home).
An object of the invention is to provide a regenerated collagen fiber with excellent heat resistance, which is less apt to be damaged even when styled with a hair iron or dryer.
SUMMARY OF THE INVENTION
Under such circumstances, as a result of intensive investigations, the inventors have found that the regenerated collagen fiber with excellent heat resistance can be obtained by compounding 1 to 100 parts by weight of a thermoplastic resin with 100 parts of collagen. Specifically, the invention is embodied in a regenerated collagen fiber comprising 100 parts by weight of collagen and 1 to 100 parts by weight of a thermoplastic resin, with the thermoplastic resin preferably being obtained by polymerizing at least one member selected from the group consisting of alkyl acrylate monomers, alkyl methacrylate monomers, acrylic acid, methacrylic acid, vinyl cyanide monomers, aromatic vinyl monomers, and halogenated vinyl monomers. The invention is also embodied in a method of producing such a regenerated collagen fiber.
BEST MODE FOR CARRYING OUT THE INVENTION
As a raw material of collagen to be used in the invention, split leather is preferred. The split leather can be obtained from a fresh raw hides or salted hides of animals such as cows. Such split leather primarily comprises insoluble collagen fibers, and is usually used after removing flesh portions attached thereto and a salt component used for preventing the leather from becoming putrid or deteriorated.
Split leather in this condition still contains impurities; for example, lipids such as glyceride, phospholipid and free fatty acids, and proteins other than collagen, such as sugar proteins and albumin. Since these impurities greatly affect (adversely) the spinning stability in forming fiber, the quality such as luster and elongation of the resultant fiber; and the odor, it is desirable to remove these impurities in advance. They may be removed, for example, by dipping split leather in lime to hydrolyze the fat components so as to loosen the collagen fiber, followed by applying a conventional hide treatment such as an acid-alkali treatment, an enzyme treatment and a solvent treatment.
The thus treated insoluble collagen is subjected to a solubilizing treatment in order to cut the crosslinking peptide portion. As such a solubilizing treatment, there may be employed an alkali solubilizing method or an enzyme solubilizing method, each of which is commonly employed as a solubilizing treatment method.
In the case of employing the alkali solubilizng method, it is desirable to neutralize the solubilized collagen with an acid such as hydrochloric acid. It is also possible to employ the method described in Japanese Patent Publication No. 15033/71 as an improved alkali solubilizing method.
The use of an enzyme solubilizing method is advantageous in that it is possible to obtain a regenerated collagen having a uniform molecular weight. Thus, an enzyme solubilizing method can be favorably employed in the invention. As such an enzyme solubilizing method, the methods described in Japanese Patent Publication No. 25829/68 or Japanese Patent Publication No. 27513/68, for example, can be employed. Incidentally, it is possible in the invention to employ in combination both the alkali solubilizing method and the enzyme solubilizing method.
Where additional treatments such as pH adjustment, salting-out, water wash and treatment with a solvent are applied to the collagen after a solubilizing treatment has been applied, it is possible to obtain a regenerated collagen fiber having an excellent quality. Thus, it is desirable to apply these additional treatments to the solubilized collagen.
The solubilized collagen leather pieces thus obtained are dissolved in an acidic aqueous solution having the pH value adjusted to 2 to 4.5 with hydrochloric acid, acetic acid, lactic acid or the like to provide a stock solution of a predetermined concentration. For example, an aqueous solution of about 1 to about 15% by weight, preferably about 2 to about 10% by weight, of collagen is prepared.
According to the invention, a thermoplastic resin is added to either solubilized collagen leather pieces before the acid is added thereto, or to an aqueous solution of collagen to which the acid has been added. In either case, the resin is added in an amount of 1 to 100 parts by weight per 100 parts by weight of collagen.
The amount of the thermoplastic resin to be compounded is preferably 3 to 80 parts by weight, and more preferably 5 to 50 parts by weight. If the amount is less than 1 part by weight, the effect of improving heat resistance tends to become insufficient whereas, in case where there is more than 100 parts by weight, the result tends to be a fragile fiber which is difficult to handle, though heat resistance is improved.
The mechanism by which heat resistance improved by compounding the thermoplastic resin is not clear, but it may be presumed that thermoplastic resin particles existing inside the regenerated collagen fiber form some structure within the fiber which functions to inhibit deformation such as contraction of collagen molecules upon heating with a hair iron or the like.
As the thermoplastic resin to be compounded, there may preferably be used those resins which are prepared by homopolymerizing or copolymerizing two or more of the monomers such as alkyl acrylate monomers (alkyl moiety containing preferably 1 to 12, more preferably 1 to 6, carbon atoms) (e.g., methyl acrylate, ethyl acrylate, butyl acrylate or octyl acrylate); alkyl methacrylate mon
Makihara Yoshihiro
Matsumura Kunihiko
Ueda Masahiro
Ueda Takashi
Brinks Hofer Gilson & Lione
Kaneka Corporation
Rajguru U. K.
Seidleck James J.
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