Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carbohydrate or derivative as a reactant
Patent
1991-10-25
1993-04-27
Kight, III, John
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carbohydrate or derivative as a reactant
527309, C08G 218, C08B 1100, C08B 3700, C08B 3716
Patent
active
052063259
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a thermoplastic graft copolymer. More particularly, the present invention relates to a thermoplastic graft copolymer comprising monosaccharide units and/or polysaccharide units as the backbone and polyacetal units as the graft, which has both excellent biodegradability and engineering resin properties, wherein the polyacetal units impart thermoplasticity to monosaccharide or polysaccharide.
BACKGROUND ART
Polyacetal resins generally have excellent mechanical properties, such as creep characteristic, fatigue characteristic, and electric properties suitable for producing engineering resins. Polyacetal resins, because of their inherent strong mechanical properties, are widely used, for example for producing automotive, electrical, and electronic parts.
Polyacetal resins are usually obtained by homopolymerizing or copolymerizing formaldehyde or trioxane with a cyclic ether, with a compound having an active hydrogen, such as water, alcohol and the like, used as a chain transfer agent. However, polyacetal resins obtained in this manner are not biodegradable.
On the other hand, while monosaccharides and polysaccharides are biodegradable, they alone cannot be used as a thermoplastic resin. At present, polysaccharides, used as a monomer, can produce thermoplastic resins, but only in a very limited capacity. For example, cellulose can be used in injection molding, extrusion, etc., after being subjected to esterification, etherification, and the like. The problem with this type of thermoplastic resins, however, is that they do not provide the necessary engineering resin mechanical properties, fatigue characteristic etc., and therefore, are not suitable for forming engineering resins.
DISCLOSURE OF THE INVENTION
The object of the present invention is to form a novel copolymer by imparting thermoplasticity to monosaccharides or polysaccharides, or to combination of both, to produce a biodegradable thermoplastic engineering resin which has excellent mechanical properties characteristic of polyacetal resins.
The present object is attained by homopolymerizing formaldehyde in the presence of monosaccharide or polysaccharide, or combination of both, to obtain a thermoplastic graft copolymer comprising monosaccharide units or polysaccharide units as the backbone and polyacetal units consisting of repetitive oxymethylene units --CH.sub.2 O-- as the graft.
Japanese Patent Application Kokoku (Post-Exam. Publn.) No. 46-22054 (1971) discloses a method of forming a polymer by subjecting trioxane and cyclic ether to a cationic polymerization in the presence of saponified cellulose ester. However, the polymer obtained in this manner not only lacks the biodegradability of the present copolymer, it also deteriorates the useful mechanical properties that are characteristic of polyacetal resin. The polymer therefore does not provide the necessary engineering resin properties.
J. Wood Chem. Technol., 3 (1), 59 (1983) discloses a polymer formed by reacting cellulose and paraformaldehyde in dimethyl sulfoxide (DMSO). Although this method effectively imparts thermoplasticity to the cellulose, it does not result in a polymer having the necessary engineering resin properties, such as those mechanical properties characteristic of the present copolymer.
BEST MODE FOR CARRYING OUT THE INVENTION
The present inventors have made extensive studies to solve the aforementioned problems. In their studies, the inventors have discovered a novel graft copolymer comprising monosaccharide units or polysaccharide units as the backbone and polyacetal units as the graft. The present graft copolymer is not only biodegradable, it has the necessary engineering resin properties.
According to the present invention, a thermoplastic graft copolymer comprises monosaccharide or polysaccharide, each having a functional group selected from the group consisting of the hydroxyl group, carboxyl group, amino group, and amido group, and polyacetal unit which is a polymer-consisting of repetitive oxymethylene units --C
REFERENCES:
patent: 3218295 (1965-11-01), Cline
patent: 3539477 (1970-11-01), Hermann
patent: 3839173 (1974-10-01), Blaszczak
Miyagi et al. in Journal of Wood Chemistry and Technology, 3(1), 59-78, Mar. 1983, article entitled "Preparation and Thermal Properties of Acetates Derived from Cellulose Dissolved in DMSO-PF".
European Search Report, Apr. 21, 1992, Application No. EP 91 90 4347.
International Search Report completed on May 20, 1991 in the Japanese Patent Office by Kunihiko SATO citing the aforementioned Japanese prior art references.
Hata Tadashige
Matsuzaki Kazuhiko
Yahiro Shiyuzi
Asahi Kasei Kogyo Kabushiki Kaisha
Culpeper Mullis Jeffrey
Kight III John
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