Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2002-08-30
2003-05-06
Acquah, Samuel A. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S357000, C524S765000, C524S768000, C524S779000, C524S783000, C527S103000, C527S300000
Reexamination Certificate
active
06559275
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for producing aliphatic polyester and a method for using glucans such as starch, cellulose etc. as a resource.
2. Related Background Art
The conventional general-purpose plastic products are composed of polymers synthesized from petroleum resources. More specifically, polymer products such as polyester, polystyrene, nylon, polyethylene, polyvinyl chloride, polyimide, polycarbonate etc. are all synthesized from petroleum. However, the petroleum is a limited resource which is to run out sooner or later. For this reason there is strongly desired a technology for producing the general-purpose plastic products from a new raw material capable of substituting petroleum, namely a recyclable raw material.
On the other hand, starch is a polymer compound formed by dehydration polymerization of D-glucose, and is an important polysaccharide comparable to cellulose. Starch is produced from potato, sweet potato, corn etc., with the worldwide production (production amount of corn) amounting to 400 to 500 million tons per year, and is a recyclable resource having the largest production amount among the natural resources. Starch can highly be expected as a new resource which replaces the petroleum, if general-purpose plastic products can be produced therefrom.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a method for producing aliphatic polyester utilizing glucans such as starch or cellulose as a raw material.
Based on a standpoint that a novel technical development is required to provide against the exhaustion of the petroleum resources in the future, the present inventors through intensive investigation have noticed starch as a raw material which can replace petroleum and have found that aliphatic polyester can be synthesized from caproic acid that can be obtained from starch via glucose, thereby attaining the present invention. This finding opens up a way for utilizing starch as an efficient resource in obtaining plastics of high quality from starch as a starting material.
The above-mentioned object can be attained, according to an embodiment of the present invention, by a method for producing an aliphatic polyester represented by the following formula (I):
(wherein n stands for an integer within a range from 5 to 10,000), the method comprising the steps of:
(i) hydrolyzing starch to obtain glucose;
(ii) oxidizing the glucose to obtain gluconolactone;
(iii) reducing the gluconolactone to obtain caproic acid;
(iv) chlorinating the caproic acid to obtain 6-chlorocaproic acid;
(v) cyclizing the 6-chlorocaproic acid to obtain &egr;-caprolactone represented by the following formula (II):
and
(vi) executing ring-opening polymerization of the &egr;-caprolactone.
The aforementioned object can be attained also, in another embodiment of the present invention, by a method for producing an aliphatic polyester represented by the following formula (I):
(wherein n stands for an integer within a range from 5 to 10,000), the method comprising the steps of:
(i) hydrolyzing starch to obtain glucose;
(ii) oxidizing the glucose to obtain gluconic acid;
(iii) reducing the gluconic acid to obtain caproic acid;
(iv) chlorinating the caproic acid to obtain 6-chlorocaproic acid;
(v) cyclizing the 6-chlorocaproic acid to obtain &egr;-caprolactone represented by the following formula
and
(vi) executing ring-opening polymerization of the &egr;-caprolactone.
&egr;-caprolactone is a compound having an intramolecular cyclic ester structure and is well known as an industrially producible compound by oxidizing cyclohexanone. It is also known that &egr;-caprolactone easily undergoes ring-opening polymerization to provide aliphatic polyester (Japanese Patent Application Laid-Open No. 11-158172). However, there have not been known examples, except that of the present inventors, of synthesizing &egr;-caprolactone from starch and obtaining aliphatic polyester therefrom.
According to the present invention, there is also provided a method for producing an aliphatic polyester represented by the following formula (I):
(wherein n stands for an integer within a range from 5 to 10,000), the method comprising the steps of:
(i) hydrolyzing glucan to obtain glucose;
(ii) oxidizing the glucose to obtain gluconolactone or gluconic acid;
(iii) reducing the gluconolactone or the gluconic acid to obtain caproic acid;
(iv) chlorinating the caproic acid to obtain 6-chlorocaproic acid;
(v) cyclizing the 6-chlorocaproic acid to obtain &egr;-caprolactone represented by the following formula (II):
and
(vi) executing ring-opening polymerization of the &egr;-caprolactone.
According to the present invention, there is also provided a method for producing an aliphatic polyester represented by the following formula (VI):
(wherein n stands for an integer within a range from 10 to 6,000), the method comprising the steps of:
(i) hydrolyzing glucan to obtain glucose;
(ii) oxidizing the glucose to obtain gluconolactone or gluconic acid;
(iii) reducing the gluconolactone or the gluconic acid to obtain caproic acid;
(iv) chlorinating the caproic acid to obtain 5-chlorocaproic acid;
(v) cyclizing the 5-chlorocaproic acid to obtain &dgr;-caprolactone; and
(vi) executing ring-opening polymerization of the &dgr;-caprolactone.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The method of the present invention for producing aliphatic polyester, in an embodiment thereof, comprises the steps of:
(i) hydrolyzing starch to obtain glucose;
(ii) oxidizing the glucose to obtain gluconolactone or gluconic acid;
(iii) reducing the gluconolactone or the gluconic acid to obtain caproic acid;
(iv) chlorinating the caproic acid to obtain 6-chlorocaproic acid;
(v) cyclizing the 6-chlorocaproic acid to obtain &egr;-caprolactone; and
(vi) executing ring-opening polymerization of the &egr;-caprolactone to obtain aliphatic polyester represented by the foregoing formula (I).
The method for synthesizing aliphatic polyester from starch opens up a novel way of utilizing starch as a resource. From this standpoint, the method of the present invention for producing aliphatic polyester also provides a useful method for utilizing starch as a new resource.
In the following there will be explained each of the aforementioned steps (i) to (vi).
Step (i) (Starch to Glucose)
Conversion from starch to glucose can be achieved for example by hydrolysis with a dilute acid such as sulfuric acid, hydrolysis with an enzyme such as amylase or maltase, or hydrolysis with ultracritical water. The step of obtaining glucose from starch is preferably executed by hydrolysis with an acid. The reaction conditions can be suitably determined according to the already known method.
Step (ii) (Glucose to Gluconolactone or Gluconic Acid)
Conversion from glucose to gluconolactone can be achieved for example by bromine oxidation of glucose or by a method utilizing notatin which is a glucose oxidase. The step of obtaining gluconolactone from glucose is preferably executed by bromine oxidation. The reaction conditions can be suitably determined according to the already known method.
Conversion from glucose to gluconic acid can be achieved for example by oxidation with bromine and concentrated sulfuric acid, more specifically oxidizing and hydrolyzing glucose in sulfuric acid saturated with bromine, or by electrolytic oxidation of a glucose solution or by fermentation of gluconic acid utilizing bacteria of Penicillium family. The step of obtaining gluconic acid from glucose is preferably executed by oxidation utilizing bromine and concentrated sulfuric acid. The reaction conditions can be suitably determined according to the already known method.
Step (iii) (Gluconolactone or Gluconic Acid to Caproic Acid)
Conversion of gluconolactone or gluconic acid to caproic acid can be achieved for example by reduction thereof with hydroiodic acid and red phosphorus. In this reaction, it is desirable that the hydroxyl group alone of gluconolactone or gluconic acid is oxidized.
The amount of red phosphorus
Kozaki Shinya
Minami Masato
Acquah Samuel A.
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
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