U.S. patent number 3,756,232 [Application Number 05/086,327] was granted by the patent office on 1973-09-04 for sanitary napkins disposable in water closet bowl with the use of alkaline agent.
This patent grant is currently assigned to SAID Noguchi, by said Saburi. Invention is credited to Koichi Noguchi, Masao Saburi.
United States Patent |
3,756,232 |
Noguchi , et al. |
September 4, 1973 |
SANITARY NAPKINS DISPOSABLE IN WATER CLOSET BOWL WITH THE USE OF
ALKALINE AGENT
Abstract
A water-dispersible sanitary napkin having an absorbent composed
of (a) a fibrous pad of short fibers of less than 1 cm of fibrous
carboxy methyl cellulose having a degree of etherification of 0.15
- 1.50 and an average degree of polymerization of more than 100 or
a mixture of these fibers with up to 70 percent of untreated short
fibers and (b) a solid alkaline agent having a pH less than 10 at
0.1 mol concentration or a solid alkali carbonate and a solid acid.
The absorbent may also contain up to 30 percent of alkaline carboxy
methyl cellulose fibers.
Inventors: |
Noguchi; Koichi (Tokyo,
JA), Saburi; Masao (Tokyo, JA) |
Assignee: |
SAID Noguchi, by said Saburi
(N/A)
|
Family
ID: |
27287033 |
Appl.
No.: |
05/086,327 |
Filed: |
November 2, 1970 |
Foreign Application Priority Data
|
|
|
|
|
Nov 12, 1969 [JA] |
|
|
44/90156 |
Apr 9, 1970 [JA] |
|
|
45/30618 |
Jun 12, 1970 [JA] |
|
|
45/50520 |
|
Current U.S.
Class: |
604/359; 604/364;
604/365; 604/376 |
Current CPC
Class: |
A61L
15/28 (20130101); A61L 15/28 (20130101); A61F
13/15211 (20130101); C08L 1/26 (20130101); A61F
2013/15227 (20130101); A61F 2013/530131 (20130101); A61F
2013/530145 (20130101); A61F 2013/51409 (20130101) |
Current International
Class: |
A61F
13/15 (20060101); A61L 15/28 (20060101); A61L
15/16 (20060101); A61f 013/16 () |
Field of
Search: |
;128/284,285,287,290,296 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Rosenbaum; Charles F.
Description
This invention relates to an improved sanitary napkin to be used
for women's menstruation.
The feature of this napkin is that it comprises an absorbent pad of
carboxy methyl cellulose short fibers, whose degree of
etherification and average degree of polymerization being under
control, and its combination with a solid weak alkali or an
alkaline source consisting of a solid alkali carbonate and a solid
acid, the said absorbent of the napkin being disposable by water
flush in alkaline water solution in closet bowl by
dissolution-dispersion and swelling-dispersion after its actual use
for the purpose, by throwing the napkin and the above mentioned
alkali agent or alkaline source into water in the bowl.
When cotton-wool napkins currently on the market are thrown into
water in a water closet bowl, they tend to clog the drain of the
water flush system because they do not swell-disperse nor
dissolve-disperse and therefore they are not good for disposal into
the water of a water closet bowl after their actual use. The
essence of this invention is for the absorbent of the sanitary
napkin to maintain its shape without dissolution by absorption and
storing of menstrual fluid during its use and also to
dissolve-disperse and swell-disperse quickly when the napkin is
thrown into water in the closet bowl after its use. The basic
feature with respect to the raw material for the absorbent in this
invention to satisfy this objective is to use short fibers of
fibrous glycolic acid as the raw material of the absorbent. Carboxy
methyl cellulose (hereinafter abbreviated as CMC) is not soluble in
water. However, in alkaline water solution, CMC becomes alkaline
CMC and dissolves. This property is applied to the absorbent of the
napkin in this invention.
The absorbent of the napkin is explained in detail hereunder:
It is necessary for the absorbent of the napkin to be basically a
fibrous pad of CMC short-fibers. The reasons for it are that a
fibrous pad of CMC does not give the wearer a disagreeable feeling
during use because of its soft pliability and that it has the
property of good absorption of menstrual fluid and good storage of
menstrual fluid absorbed because of its large porous space and also
that it has a good chemical property in that it dissolves and
disperses instantly in weak alkaline water solution. It is
generally very difficult to convert CMC to alkaline carboxy methyl
cellulose (hereinafter called Na-CMC, taking sodium carboxy methyl
cellulose as the most representative of alkaline carboxy methyl
cellulose,) quickly and for this purpose, a strong alkali such as
caustic soda (NaOH) and also some lengthy reaction time as well as
such treatments as heating, stirring etc. are necessary. However,
if the structure of CMC is a fibrous mass, it reacts well with weak
alkaline water solution standing still at normal temperature,
produced by a weak alkaline agent because of its very good property
of reacting to alkaline water solution. The reason for this is that
the structure of a fibrous mass being in the state that CMC short
fibers are closely associated in a tangled mass but without being
combined together and having large void spaces in it, alkaline
water solution is absorbed all at once into the fibrous pad by
wicking action when the fibrous pad is thrown into alkaline water
solution and that when the fibrous pad absorbs alkaline water
solution, the entire surfaces of the CMC short-fibers forming the
fibrous pad contact the alkaline water solution and consequently
the reactivity of the fibrous pad with the alkaline water solution
is increased substantially.
CMC short fibers to swell quickly when contacted with alkaline
water solution and the degree of swelling (hereinafter called DS)
of CMC short fibers, increases in proportion to the degree of
etherification (hereinafter called DE) of CMC short-fibers.
Therefore, CMC short-fibers of fibrous pad which absorbed alkaline
water solution swell by contact with alkaline water solution and
when the DE of CMC short fibers is large, the degree of swelling
increases further whereby the lengths of CMC fibers are shortened
and the linear structures of CMC short fibers are destroyed. In
addition to swelling of CMC short fibers, CMC short fibers react
with alkaline water solution and partly dissolve because of the
change of CMC to Na-CMC. In summing up, CMC fibrous pad reacts with
alkaline water solution thereby shrinkage of length,
swelling-decomposition and dissolution of CMC short fibers take
place simultaneously and the entanglement of CMC short fibers
forming the fibrous pad is loosened and the entire entanglement of
the fibrous mass is untied all at once and thus the fibrous pad
dissolves-disperses and swell-disperses in the alkaline water
solution. It is featured that such a dissolution-dispersion and
swelling-dispersion of the fibrous pad take place easily and
promptly in a weak alkaline water solution because the degree of
reaction of the fibrous pad to alkaline water solution is very
large. Contrary to this, it has been proven by experiments that
such CMC materials of high density as CMC-paper or CMC gauze
dissolved in strong alkaline solution (0.1 mol concentration at
normal temperature - hereinafter, pH values are all stated on this
basis) having a pH of more than 12 such as NaOH but did not
dissolve for a long time at normal temperature in saturated
alkaline water solution of sodium carbonate (Na.sub.2 CO.sub.3) the
pH of which is 11.5. On the other hand, a CMC fibrous mass reacts
very easily and dissolves, swells and disperses in a still water
solution of NaHCO.sub.3 (pH 8.3 ) at normal temperature. Since the
alkaline agent to be used with the napkin should be safe to the
human body, strong alkaline agents such as NaOH or Na.sub.2
CO.sub.3 whose pH is higher than 10, are dangerous and unfit to be
used for the napkin of this invention. However NaHCO.sub.3 (pH 8.3)
which is safe to the human body, is effectively usable. This is
because the absorbent of the napkin of this invention is formed by
a CMC fibrous mass and this is the special feature of the napkin of
this invention.
Firstly, it is necessary that the CMC fibers forming the fibrous
pad be short fibers having a length less than 1 cm. It has been
proven by experiments that if the CMC fibers forming a fibrous pad
are more than 1 cm long, the CMC fibrous pad does not
dissolve-disperse nor swell-disperse (hereinafter called, in
combination, dissolve-disperse) in a weak alkaline water solution
of an alkaline agent having a pH less than 10, due to tight
entanglement of the fibers. Therefore, in order to ensure easy and
prompt dissolution-dispersion of the CMC fibrous pad in alkaline
water solution of the alkaline agent having a pH less than 10, it
is necessary that the entanglement of CMC fibers of the fibrous pad
be loose and for this, the length of the CMC fibers must be shorter
than 1 cm.
Secondly, the effect of DE and average degree of polymerization
(hereinafter called as DP) of the CMC fibers forming the fibrous
pad to the pliability, dissolution-dispersibility and
swelling-dispersibility of the fibrous pad is explained
hereunder:
Regarding Relationship between DE and Pliability.
As the DE increases, the pliability becomes worse and the CMC-short
fibers become harder and thus become unfit for the absorbent. In
this sense, there should exist a maximum limit value for DE. When
CMC short fibers become hard, their defibration becomes impossible.
The maximum limiting value of DE is about 1.5. Of course, the
smaller the DE, the better the pliability.
Regarding Relationship between DE and
Solubility-Dispersibility.
With an increase in DE, the degree of reaction of CMC fibers to
alkaline water solution increases. That is, DE and the reactivity
are directly proportional i.e. DE and the solubility-dispersibility
are directly proportional. On the other hand, when the DE decreases
and falls below a certain limit, the reactivity between CMC fibers
and alkaline water solution decreases and the
dissolution-dispersion of the fibrous mass becomes impossible.
Thus, there should exist a minimum limit for DE at which the CMC
fibrous mass dissolves-disperses.
Regarding Relationship between DP and Pliability.
As the DP decreases, the fibers become fragile and lose pliability.
Therefore, when the DP is decreased too much, the linear structure
of the short fibers is destroyed. Thus, there should exist a
minimum limit value for DP.
Regarding Relationship between DP and
Solubility-Dispersibility.
As the DP decreases, the dispersibility increases.
Summing up the above, it is necessary to control the DE and DP in
such a way as to maintain good pliability and
solubility-dispersibility so as to make the fibrous mass suitable
as the absorbent of the napkin.
Thirdly, the alkaline agent is explained hereunder:
It is necessary that the alkaline agent be solid. As the alkaline
agent is required to be present always together with the napkin, it
is necessary that it be a solid alkaline agent convenient to be
carried and to be incorporated in the napkin.
Also, it is necessary that the alkaline agent be safe to human body
and clothing. Since the alkaline agent is to be used by an infinite
number of persons, it should always be positively safe. Therefore,
an agent having a pH higher than 10 can not be used.
Also, it must be a weak alkaline agent which will not cause the
death of bacteria which promote putrefaction of night soil in a
septic tank. Since it is said that the pH necessary to keep
bacteria alive in a septic tank is within the range of about 6 - 8,
it should be a weak alkaline agent such as NaHCO.sub.3 whose pH is
8.3, in order to maintain the pH of the liquid in the septic tank
within the range of 6 - 8.
Hereinunder the explained the features of the sanitary napkins
comprising the combination of napkin and alkaline agent covered by
this invention:
Sanitary napkins consisting of a combination of (a) an absorbent
which is a fibrous pad of short fibers of less than 1 cm of fibrous
glycolic acid of degree of etherification of 0.15 - 1.50 and of
average degree of polymerization of more than 100 or is a fibrous
pad made by mixing untreated short fibers not subjected to chemical
treatment with the above mentioned fibrous pad within 70 percent
and (b) a solid alkaline agent whose pH is lower than 10 at 0.1 mol
concentration and at room temperature, the said napkin being
disposable by water flushing by combined use of an alkaline agent,
featured by being designed for easy disposal by
dissolution-dispersion of the absorbent of the napkin in an
alkaline water solution when the used napkin and the above
mentioned alkaline agent are thrown into water in a water closet
bowl.
This napkin is explained in detail hereunder:
When the napkin is disposed in this combination, there is a problem
in that, since the solid alkaline agent, when thrown into water in
a closet bowl, sinks to the bottom of the water and commences
dissolution there, the water in the upper part does not become
alkaline for a short while after throwing the alkaline agent into
water, it being still. Therefore, in this case, it is necessary to
make the entire water alkaline quickly by stirring the water after
throwing in the alkaline agent or to delay the throwing of the
napkin for a until the upper part of the water becomes
alkaline.
As for the DE and DP of the absorbent of the napkin in this
invention, the maximum value of DE is 1.50 as aforementioned since
the absorbent fibrous pad is made of difibrated short fibers and
the minimum value of DE which is, as aforementioned, the lowest
capable of dissolving-dispersing the fibrous pad quickly, is within
the range of 0.34 - 0.27 and generally about 0.30 in case of normal
degree of polymerization (DP's of more than 500 are called normal
degree of polymerization) as illustrated in Experiment 1.
Fourthly, it was mentioned before that the dispersibility of the
CMC fibrous mass increases in accordance with the decrease in DP
and it was then examined in Experiment 2 to find out how far the
minimum DE among those capable of dissolving-dispersing the CMC
fibrous pad may be decreased from the DE (about 0.3) of normal
degree of polymerization, by lowering the DP less than the normal
degree of polymerization. Also in Experiment 2, the optimum point
in respect of the pliability of the CMC fibrous mass suitable for
napkins was examined since the pliability of the fibrous mass is
worsened when the DP is decreased. There are various methods to
decrease DP. For industry purpose for making CMC fibers, the DP may
be arbitrarily controlled by adjusting dipping time of raw material
cellulose in NaOH solution in the process of making alkaline
cellulose, i.e., the longer the dipping time, the smaller the DP.
In Experiment 2, CMC fibers were dipped in hydrogen peroxide
(H.sub.2 O.sub.2)AND DP's were controlled by length of this dipping
time. In Experiment 2, a CMC fibrous mass of DE 0.27 and of DP 564
was used as a test piece and this fibrous mass did not
dissolve-disperse in alkaline water solution as mentioned in
Experiment 1 but it dissolved-dispersed within about two seconds
after being thrown into NaHCO.sub.3 solution because its DP
decreased to 243 by dipping in H.sub.2 O.sub.2 for 48 hours. Such
being the case, a CMC fibrous mass does not dissolve-disperse in
the case of normal DP but dissolves-disperses at decreased DP.
Using this property, Experiment 3 was exercised to find out the
lowest DE at which the CMC fibrous mass was dissolved-dispersed
under the state of its DP being extremely lowered but within such a
limit of DP that the shape of the CMC fibrous mass is maintained
(DP about 100 - 200). The test pieces used in this Experiment
consisted of a CMC fibrous mass having a DP more than 500 which
were dipped in H.sub.2 O.sub.2 for 72 hours to decrease their DP's
to the range of about DP 100 - 200 and the
solubility-dispersibility was examined with the test pieces having
small DE's. In this experiment, a CMC fibrous mass of DE 0.197
dissolved-dispersed quickly but those of DE 0.148 and DE0.043 did
not dissolve-disperse. From this, it has been ascertained that the
minimum value of DE at which a CMC fibrous mass of DP 100 - 200
dissolves-disperses, was within the range of DE 0.197 - 0.148 and
was about 0.15. As for the cases in which untreated short fibers
not subjected to chemical treatment are evenly mixed with the CMC
fibrous pad of the napkin in this paragraph, it has been confirmed
in Experiment 5 that the absorbent could dissolve-disperse when the
mixing proportion was less than 70 percent. The effect of mixing
untreated short fibers is that it is naturally economical to mix as
much untreated short fibers as possible because untreated short
fibers are cheaper than CMC short fibers. Those fibers which are
mentioned here as chemically untreated short fibers are all the
fibers other than the CMC fibers essentially relating to
swelling-dispersion and dissolution-dispersion of the absorbent of
the napkin of this invention and Na-CMC fibers. For example,
alkaline cellulose fibers are the fibers which are chemically
treated but which do not dissolve-disperse by themselves in water
or alkaline water solution. Therefore, they are deemed here as
chemically untreated fibers. Also even when additive(s) are applied
to the fibers, those fibers are regarded as chemically untreated
fibers as long as they do not dissolve-disperse in water nor in
alkaline water solution by themselves.
As for the alkaline agent to be used in combination with the napkin
in this invention, it is necessary that it be a solid alkaline
agent which, as mentioned before in the paragraph concerning the
conditions of alkali, is positively safe to the human body and
clothing and does not cause death of bacteria in septic tank. For
this reason, many strong alkaline agents having a pH more than 10
as NaOH, Na.sub.2 CO.sub.3 etc. may not be used in combination with
he napkin in this invention because of their likely hazard and
trouble. Alkaline agents of pH lower than 10 are suitable as
alkaline agents to be used in combination with the napkin in this
invention because they are safe to the human body and also, the pH
in the septic tank will be lowered by the large quantity of used
for flushing. NaHCO.sub.3 is one of the most suitable examples of
the alkaline agent for this use.
Fifthly, explanations are made about a sanitary napkin consisting
of a combination of (a) an absorbent which is a fibrous pad made by
mixing alkaline carboxy methyl cellulose fibers within 30 percent,
with the fibrous mass of short fibers of less than 1 cm of fibrous
glycolic acid having a degree of etherification of 0.15 - 1.50 and
an average degree of polymerization of more than 100 or with the
fibrous mass made by mixing untreated short fibers not subjected to
chemical treatment within 70 percent with the above mentioned
latter CMC fibrous mass and (b) a solid alkaline agent whose pH is
lower than 10 at 0.1 mol concentration and at room temperature, the
said napkin being disposable by water flushing by combined use of
an alkaline agent, featured by being designed for easy disposal by
dissolution-dispersion of the absorbent of the napkin in alkaline
water solution when the used napkin and the above mentioned
alkaline agent are thrown into water in a water closet bowl, as
follows:
The absorbent of this napkin maintains its shape during its use
with absorption of menstrual fluid as long as the proportion of
Na-CMC short fibers in the absorbent is within 30 percent but it is
featured that this mixing has an effect to prevent the binding of
the short fibers of the absorbent caused by coagulation of
menstrual fluid to some extent. (Since it has been ascertained by
results of the actual application tests exercised by the inventor
that the part of the short fibers of the absorbent which are bound
together by coagulation of menstrual fluid is only 5 percent of all
short fibers of the absorbent and so it does not cause any trouble
to the disposal of the napkin in its practical use). The experiment
regarding the maximum permissible proportion of Na-CMC fibers is
illustrated in Experiment 4.
Sixthly, explanations are made about a sanitary napkin consisting
of a combination of (a) an absorbent which is a fibrous pad of
short fibers of less than 1 cm of fibrous glycolic acid having a
degree of etherification of 0.10 - 0.15 and an average degree of
polymerization of more than 100 or a fibrous pad made by mixing
untreated short fibers not subjected to chemical treatment within
70 percent with the above mentioned fibrous mass and (b) an alkali
source composed of a solid alkali carbonate and a solid acid, the
said napkin being disposable by water flushing by combined use of
an alkali source, featured by being designed for easy disposal by
dissolution-dispersion of the absorbent of the napkin in alkaline
water solution when the used napkin and the above mentioned alkali
source are thrown into water in a closet bowl, as follows:
For some time after the alkaline agent used for disposal of the
previously mentioned napkin is thrown into water in a closet bowl,
the upper part of the water does not change to the alkaline state.
Therefore, there is a defect that even when the napkin is thrown
into water after the alkaline agent is put into water, the
absorbent of the napkin does not dissolve-disperse for a long time
because it absorbs the water of the upper part and, the water
staying still, the exchange of water in it with alkaline water
solution does not take place. However, when an alkali source
composed of an alkali carbonate and an acid is used in combination
with the napkin in this invention, a large amount of CO.sub.2 gas
is generated by reaction of the alkali carbonate and acid in water
which agitates the water in the closet bowl and changes the water
evenly to an alkaline state. Therefore, in the case of the napkin
of this invention, the absorbent dissolves-disperses quickly
because, when the napkin is thrown into water after the alkali
source is put into water, an alkaline solution is forced into the
absorbent by CO.sub.2 gas. In this way, the alkali source in this
invention has a feature that, when put into water in a closet bowl,
it generates actively CO.sub.2 gas, agitates the water, thus
bringing the water quickly to an even alkaline state and also,
accelerates dissolution-dispersion of the absorbent by compulsory
forcing alkaline water solution into the absorbent. Additionally,
the alkali source in this paragraph has the following features
useful for disposal of napkins:
It has an effect to push out the menstrual fluid absorbed in the
absorbent and thus to make dissolution-dispersion of the absorbent
easy. It is because CO.sub.2 gas generated in a large quantity
penetrates forcefully into the absorbent and pushes out the
menstrual fluid already absorbed in the absorbent and, instead,
delivers alkaline solution into the absorbent so that the absorbent
may be dissolved-dispersed quickly. It has also an effect to
improve the reaction between the absorbent and the alkaline
solution because CO.sub.2 gas generated in a large quantity
penetrates forcefully and continuously into the absorbent and as a
result of this, the CMC absorbent fibrous pad contacts continuously
fresh alkaline solution and, the reactivity of the absorbent with
alkaline solution being improved, dissolution-dispersion of the
absorbent becomes easy. Also, even when the alkalinity of the
alkaline solution is weak, the absorbent dissolves-disperses easily
in the alkaline solution.
Also, it has an effect that the absorbent dissolves-disperses in
alkaline solution easily even when, the order of throw-in being
reversed, the napkin is thrown into the water in the closet bowl
prior to the alkali source. As mentioned before, when the napkin is
thrown into water prior to the alkali agent, the water penetrates
into the absorbent and, even with subsequent throw-in of alkali
agent into the water, the exchange of the water in the absorbent
with the alkaline solution does not take place since the alkaline
solution stays still and the absorbent does not dissolve-disperse
for a long time. However, in case of the alkali source in this
invention, it is featured that, even when the napkin is thrown into
water prior to the alkali source, the generation of a large amount
of CO.sub.2 gas causes quick exchange of the water in the absorbent
with the alkaline solution and the absorbent dissolves-disperses
quickly.
Also, since this alkali source contains an acid, it has a feature
that the alkalinity due to alkaline agent is reduced and thus, the
lives of bacteria in domestic septic tanks are saved.
This alkali source is entirely safe to the lives of bacteria in
septic tanks because the pH of the water in the closet bowl may be
perfectly controlled within a range of about 7.0 - 7.5 by adjusting
the quantity of the acid to that of the alkali carbonate.
The features regarding the effects of using an alkali source in
combination with the napkin are mentioned above and explanations
are made hereinafter about the solid alkali carbonate and the solid
acid composing this alkali source. Of course, a solid alkali
carbonate and a solid acid very safe to human body and clothing
should be employed and their dosages for use should be formulated
beforehand to make the alkalinity of the water in the closet bowl
within a pH range of about 7.0 - 7.5. The best example is to use a
combination of NaHCO.sub.3 as the alkali carbonate and citric acid
as the acid.
Next, as for the DE of the absorbent of the napkin in this
invention the minimum value of DE at which the absorbent can
dissolve-disperse is lower than that of the DE of the absorbent of
the aforementioned napkin (about 0.3) because the reactivity of the
absorbent is improved by CO.sub.2 gas and, as provided in
Experiment 6, it is about 0.15. The DP in this case is a normal
degree of polymerization i.e. about 500 - 600 but if the DP is
decreased to lower than normal degree of polymerization, the DE is
further lowered and it has been proven as provided in Experiment 7,
that the DE is about 0.10. The fact that the DE of the absorbent
may be decreased by the use of an alkali source means that the
pliability and sponginess of the absorbent is fully secured.
Seventhly, explanations are made about a sanitary napkin consisting
of a combination of (a) an absorbent which is a fibrous pad made by
mixing alkaline carboxy methyl cellulose fibers within 30 percent
with the fibrous mass of short fibers of less than 1 cm of fibrous
glycolic acid of degree of etherification of 0.10 - 1.50 and of
average degree of polymerization of more than 100 or with the
fibrous mass made by mixing untreated short fibers not subjected to
chemical treatment within 70 percent with the above mentioned
latter CMC fibrous mass and (b) an alkali source composed of a
solid alkali carbonate and a solid acid, the said napkin being
disposable by water flushing by combined use of an alkali source,
featured by being designed for easy disposal by
dissolution-dispersion of the absorbent of the napkin in alkaline
water solution when the used napkin and the above mentioned alkali
source are thrown into water in a closet bowl, as follows:
The special feature of this napkin is that, although the effect of
mixing Na-CMC is the same as that of the previously mentioned
napkin, the dissolution-dispersion of the absorbent is quicker and
more positive than that of the previously mentioned napkin since
the alkali source is employed.
Eighthly, the inventor illustrates hereunder the experiments on
which the foregoing explanations are based:
Experiment 1.
Experiment on DE of CMC fibers, the absorbent fibrous pad of these
CMC short fibers of less than 1 cm being capable to
dissolve-disperse by combined use of the napkin and the alkaline
agent.
Kind of material Wood-pulp of defibrated short fibers.
Size, form and weight of material
1 gram in a cylindrical form of 2 cm in diameter and 2 cm in
height.
State of material
Under pressed condition, water is absorbed in more than 2/3 parts
of the cylinder.
Length of CMC short fiber materials
2 to 4 millimeters.
Dp of material 500 - 600.
Alkaline agent NaHCO.sub.3 10 grams.
H.sub.2 o 1,000 cc
Time of dipping of material
Immediately after throwing alkaline agent into water and stirring
up the liquid.
(DE of CMC) (State of dissolution-dispersion)
1. 0.27 No dissolution-dispersion even after 30 minutes.
2. 0.34 Dissolved-dispersed within about 2 seconds.
3. 0.45 Dissolved-dispersed within about 1 second.
4. 0.50 The same as above.
5. 0.70 The same as above.
6. 0.90 The same as above.
Comment:
The minimum value of DE at which the material dissolves-disperses
is between 0.27 and 0.34. It is about 0.30.
Experiment 2.
Experiment on dissolution-dispersion of CMC fibrous pad of CMC
short fibers of DE 0.27 and DP 564, this DP having been decreased
by immersion in H.sub.2 O.sub.2 and this fibrous pad on being
thrown into water in combination with an alkaline agent.
Material of DE 0.27 in Experiment 1 was employed in this
experiment.
Kind of material, size, form and state of material etc. were the
same as those in Experiment 1.
Weight of Material 5 grams.
Length of CMC short fibers 2 to 4 millimeters
H.sub.2 o.sub.2 30 percent concentration, 500 cc.
Dp and DE of material before immersion in H.sub.2 O.sub.2
De 0.27 dp 564
alkaline agent NaHCO.sub.3 10 grams
H.sub.2 o 1,000 cc
Time of dipping of material
Immediately after throwing the alkaline agent into water and
stirring up the liquid.
(Time of immer (Average degree of (State of dissolu sion in H.sub.2
O.sub.2) polymerization: DP) tion-dispersion) hours (1) 44 319 No
dissolution-dis persion. (2) 48 243 Dissolved-dispersed within
about 2 - 3 seconds. (3) 52 227 Dissolved-dispersed within about 1
- 2 seconds. (4) 56 213 Dissolved-dispersed within about 1 second.
Most of material completely dissolved within about 1 minute. (5) 61
205 The same as above. (6) 69 151 The same as above. (7) 81 132 The
same as above. (8) 95 110 The same as above.
Comment:
Immersion for 48 hours provides DP 243 and from this DP,
dissolution-dispersion begins and all the materials of DP lower
than this dissolve-disperse but the lowest limit of DP at which the
pliability is suitable for the absorbent of the napkin is about
110.
Experiment 3.
Experiment on dissolution-dispersion of CMC fibrous pad, these CMC
short fibers being of low DE and having low DP within a range of
100 - 200 as result of immersion of CMC short fiber cotton-wool
congregation in H.sub.2 O.sub.2 for 72 hours.
Kind, size, form, state etc. of material the same as those in
Experiment 1.
Weight of material 5 grams.
Length of CMC short fibers 2 to 4 millimeters.
Dp of material 10 100 - 200
Alkaline agent NaHCO.sub.3 10 grams
H.sub.2 o 1,000 cc
Time of dipping of material
Immediately after throwing alkaline agent into water and stirring
up the liquid.
(DE of CMC) (State of dissolution-dispersion)
1. 0.043 No dissolution-dispersion even after 30 minutes.
2. 0.148 Same as above.
3. 0.197 Dissolved-dispersed within about 3 seconds.
Comment:
It has been known from this that the minimum value of DE at which
CMC fibrous mass of DP 100 - 200 fell within a range between 0.197
and 0.148.
It is about 0.150.
Experiment 4.
Experiment on durability of maintaining forms of the absorbent
during use when Na-CMC short fibers are evenly mixed in the
absorbent of CMC short fibers.
Kind, form, weight, state etc. of material the same as those in
Experiment 1
Length of CMC short fibers 2 to 4 millimeters
Length of Na-CMC short fibers 2 to 4 millimeters
Alkaline agent NaHCO.sub.3 10 grams
H.sub.2 o 1,000 cc.
Time of dipping of material
Immediately after throwing alkaline agent into water and stirring
up the liquid.
(Na-CMC mixing ratio (Durability of maintaining in % ) the form of
the material) 10 When H.sub.2 O was soaked in the material, its
form was not decomposed. 20 The same as above. 30 The form of the
material was somewhat destroyed. 40 The form of the material was
completely destroyed.
Comment:
When Na-CMC is mixed at 40 percent, the form is completely
destroyed by water. Therefore, the practical limit is 30
percent.
Experiment 5.
Experiment on solubility-dispersability of the absorbent when
chemically untreated short fibers are evenly mixed in the absorbent
of CMC short fibers.
Kind, size, form, weight, state etc. of material the same as those
in Experiment 1
Length of CMC short fibers 2 to 4 millimeters
Length of untreated short fibers 2 to 6 millimeters
Alkaline agent NaHCO.sub.3 10 grams
H.sub.2 o 1,000 cc
Time of dipping of material
Immediately after throwing alkaline agent into water and stirring
up the liquid.
(Mixing ratio of chemical- ly untreated short (Solubility- fibers
in %) Dispersability) 10 Good 20 Good 30 Good 40 Good 50 Hardly
dissolution-dispersion but dispersed by stirring the liquid 60 The
same as above. 70 No dissolution-dispersion even with agitation of
the liquid.
Comment:
When the chemically untreated short fibers are mixed at 70 percent,
the absorbent does not dissolve-disperse. Therefore, the practical
limit of the chemically untreated fibers is 70 percent.
Experiment 6.
Experiment on DE of CMC fibrous mass the CMC short fiber absorbent
of which dissolves-disperses under combined use of the napkin with
an alkali source composed of an alkali carbonate and acid.
Kind, size, form, weight,
850000000000000000000000000000000000000000000000000000000000000000
* * * * *