Tobacco – Smoke separator or treater – Having a polymer
Reexamination Certificate
1999-11-30
2003-06-03
Griffin, Steven P. (Department: 1731)
Tobacco
Smoke separator or treater
Having a polymer
C131S331000, C131S334000, C428S364000, C428S393000, C428S339000, C106S162700, C106S162720, C106S170260, C106S170420, C106S170460, C106S171100
Reexamination Certificate
active
06571802
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a molded article of biodegradable cellulose acetate and a filter plug for a smoking article.
Cellulose acetate is widely used as various molded articles, for example, fibers for tobacco filter materials and for woven fabric for clothes, and as films, as well as molded articles prepared by an injection molding, an extrusion molding, etc.
Cellulose acetate, which is prepared by converting cellulose into an acetic acid ester, is essentially a biodegradable substance. However, the biodegradability of cellulose acetate is not necessarily satisfactory in practice.
Specifically, even if buried in, for example, soil, a molded article made of cellulose acetate retains its original shape for 1 or 2 years. It takes a very long time for the molded article to be decomposed completely by biodegradation. These molded articles are handled as waste materials in some cases so as to be used for the land reclamation. In other cases, these molded articles are not recovered so as to be left as they are in the natural environment. It follows that it is very important to accelerate the biodegradability of cellulose acetate.
Under the circumstances, various researches are being made vigorously on the biodegradability of cellulose acetate. According to reports on the researches, the biodegradability of cellulose acetate is dependent on DS (Degree of Substitution: the number of acetyl groups per anhydroglucose monomer). To be more specific, as DS of cellulose acetate decreases, the biodegradation rate of cellulose acetate becomes faster. The mechanism of biodegradation is considered to be as follows.
First of all, the acetyl group of cellulose acetate is broken by an extracellular enzyme released from bacteria, leading to decrease in the DS value of cellulose acetate. Then, the cellulose acetate having its DS value decreased is readily undergone an enzyme decomposition by cellulase, etc. widely distributed in the environment so as to receive finally a biological metabolism and, thus, to be decomposed into carbon dioxide and water. The rate-limiting step of the biodegradation rate is considered to be the initial breakage of the acetyl group.
Based on these ideas, several methods have been proposed for accelerating the biodegradation rate of cellulose acetate. For example, Japanese Patent Disclosure (Kokai) No. 6-199901 discloses a method of controlling the biodegradability of cellulose acetate by adding an acid compound having an acid dissociation constant larger than that of acetic acid to cellulose acetate. In this method, however, the cellulose acetate chemically brings about a hydrolysis under the influence of the acid compound immediately after the time when the acid compound is added to the cellulose acetate, and the DS value of the cellulose acetate begins to be decreased. Since the DS value of the cellulose acetate composition (article) having the acid compound added thereto is thus decreased with time, it is impossible to maintain the DS value of the starting cellulose acetate.
The DS value of cellulose acetate greatly affects the function of the cellulose acetate article. When it comes to, for example, a filter for tobacco, the taste of the tobacco is greatly changed by the change in the DS value of cellulose acetate. Naturally, in terms of the quality control of the tobacco article, it is quite undesirable for the DS value of cellulose acetate used as a filter for tobacco to be changed with time from the design value under the ordinary environment, up to the time when the tobacco is smoked.
Further, the chemical hydrolysis of the acetyl group of cellulose acetate occurring in the presence of the acid compound produces acetic acid with progress of the chemical hydrolysis, i.e., with decrease in the DS value of cellulose acetate. In other words, the acetyl group eliminated from cellulose acetate is liberated as acetic acid. The liberated acetic acid imparts a strong acetic acid odor to the cellulose acetate article. The acetic acid odor is not a desirable factor in various articles. In the case of, for example, a filter for tobacco, the acetic acid odor markedly deteriorates the taste of tobacco.
BRIEF SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a means for accelerating the biodegradability of cellulose acetate, which permits suppressing the change with time in the DS value of cellulose acetate and also permits suppressing the generation of the acetic acid odor.
As a result of an extensive research conducted in an attempt to achieve the above-noted object, the present inventors have found that, by complexing a certain decomposition accelerating agent which accelerates the decomposition of cellulose acetate with a certain reaction controlling agent which suppresses the decomposition reaction of cellulose acetate, the decomposition accelerating function of the decomposition accelerating agent can be suppressed under the ordinary use conditions of cellulose acetate, but the composite material dissociates its complexed state only when the cellulose acetate is brought into contact with water, to liberate the reaction controlling agent within the composite material, thereby allowing the decomposition accelerating agent to exhibit its decomposition accelerating function.
Thus, the above object is achieved according to the present invention by cellulose acetate, having contained therein, a composite material of a decomposition accelerating agent consisting of at least one compound selected from the group consisting of oxygen acid of phosphorus, oxygen acid of sulfur, oxygen acid of nitrogen, a partial ester or hydrogen salt of these oxygen acids, carbonic acid and its hydrogen salt, a sulfonic acid, and a carboxylic acid with a reaction controlling agent consisting of at least one compound selected from the group consisting of a nitrogen-containing compound, a hydroxy compound, an oxygen-containing heterocyclic compound, and a sulfur-containing heterocyclic compound.
The cellulose acetate composition of the present invention containing cellulose acetate and a composite material, contained in the cellulose acetate, of the decomposition accelerating agent with the reaction controlling agent permits suppressing the change with time in the DS value of the cellulose acetate. Therefore, the composition of the present invention permits maintaining the article performance as designed and also permits suppressing the acetic acid odor. In addition, the cellulose acetate composition of the present invention provides a molded article that begins to be decomposed only when the article is brought into contact with water.
The cellulose acetate composition of the present invention is provided as a molded article such as fibers.
According to another aspect of the present invention, there is provided a filter plug for tobacco, comprising cellulose acetate fibers, characterized in that each of the cellulose acetate fibers contains, in at least a surface region thereof, a composite material of a decomposition accelerating agent consisting of at least one compound selected from the group consisting of oxygen acid of phosphorus, oxygen acid of sulfur, oxygen acid of nitrogen, a partial ester or hydrogen salt of these oxygen acids, carbonic acid and its hydrogen salt, a sulfonic acid and a carboxylic acid, with a reaction controlling agent consisting of at least one compound selected from the group consisting of a nitrogen-containing compound, a hydroxy compound, an oxygen-containing heterocyclic compound, and a sulfur-containing heterocyclic compound.
In the present invention, it is desirable for the cellulose acetate to have a DS value of 2.0 to 2.6.
Also, in the present invention, the decomposition accelerating agent preferably consists of at least one compound selected from the group consisting of phosphoric acid, polyphosphoric acid, phytic acid, starch phosphate, cellulose phosphate, calcium hydrogenphosphate, lecithin and phosphoric acid di-2-ethylhexyl ester; and phosphoric ester of 2-hydroxyethyl methacrylate, pho
Birch & Stewart Kolasch & Birch, LLP
Griffin Steven P.
Japan Tobacco Inc.
Walls Dionne A.
LandOfFree
Molded article of biodegradable cellulose acetate and filter... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Molded article of biodegradable cellulose acetate and filter..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Molded article of biodegradable cellulose acetate and filter... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3118352