Note: Descriptions are shown in the official language in which they were submitted.
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BACK GROUND O~ THE INVENTION
~;eld of the Invent;on
This invention relates to a water setting (water solidifying~ paper or a
high wa-ter-absorbency material in sheet form containing high water-absorbency
resin.
Description of the Prior Art
It is generally known that paper produced from paper-making materials
containing carboxymethylcellulose (CMC-H) or corboxyethylcellulose (C~C-}I), andthe respective aluminum salt, barium salt, zinc salt, tin salt and manganese
salt thereof (CMC-~l, CMC-Ba, CMC-Zn, C~C-Sn, CMC-I~n, CEC-~l, C~C-Ba, CLC-~n,
CEC-Sn, CEC-~n) are water-soluble or have the property of becoming rapidly
dispersed in water. Water-soluble paper is utili~ed as the paper for secret
documents and for water-soluble labels. ~ethods for manufacturing paper
that is water-soluble or which disperses rapidly in water are disclosed in, for
example, Japanese Laid-open Pa-tent No. 38-(1963) 25,159, Japanese Laid-open
Patent ,No. 39-(1964? 152, Japanese Laid-open Patent No. 40-(1965) 968, JapaneseLaid-open Patent No. 42-(1967) 2,925, Japanese Laid-open Pa-tent No. 43-(1968)
1,214 and Japanese Laid-open Patent No, 48-(1973) 27,605~
Also, because high water-absorbency resins of the grafted-starch series,
cellulose series and polyacrylic acid series have higher water--absorbency than
conventional water-absorbing materials such as cotton, cloth, sponge and tissue
paper, they are used in sanitary napkins, paper diapers, underpads and the like.}ligh water-absorbency resin is used by encapsulation or inclusion of the
resin in non-woven fabrics or pulp products such as tissue paper and the like
which are then disposed at an inner portion of the sanitary napkin, paper
diaper and so forth, so that the water content of the voided urine and the like
passing through the paper is absorbed and solidified at the inner portion, with
even the surface moisture of the paper itself being absorbed, providing the
products with a clean feeling in use.
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Disposal following urination has been a prohlem in the case of
conventional urine containers such as ur;ne bottles and portable toilets, the
drawback being that urine that has been collected in the container is spilled
when the container is moved or shaken, soil;ng the surroundings. To eliminate
this drawback, conventionally high water-absorbencY resin has been placed insidethe urine bottle or other such urine container to solidify the urine.
Another method that has been advanced has involved encapsulating the said high
water-absorbency resin inside a non-waven fabric or pulp product, and inserting
the thus-prepared product into the urine container.
However, because with this method the high water-absorbency resin is
enveloped in pulp, it becomes interlocked with the long pulp fibers and is not
easily dissolved. And with respect also to disposal, because it does not
readily dissolve in water, it is not possible to flush it down flush toilets.
Therefore the only way the product could be dissolved after use was by means of
formerly used methods such as incineration.
With the method involving the spreading of high water-absorbency resin as
it is in the urine container, the spreading took time, and as the resin was
inserted in particulate form, it had the drawback of being inconvenient to storeand handle. Then again, because particulate resin reacts with small amounts
of liquid and sets starting at the surface, resin which is lying thereunder and
therefore not exposed to the surface loses any chance of being involved in the
reaction owing to the setting of the surface resin, so that in many cases it
remains in the urine container in a state of incomplete reaction ~agglomerate
state). In order to activate it, it is necessary to stir up to underlying
resin to bring it to the surface, but as in fact this is unhygienic, it is
usually disposed of in its entirety.
SUMM~RY OF TIIE INVENTION
It is an object of this invention to provide a high water-absorbency
material in sheet form water setting ~water-solidifying) paper which enables
the urine in a urine bottle or suchl;ke urine container or portable toilet to be
28025g3
disposed of easily, rapidly and hygienically and can be applied widely in many
other ways.
The water setting paper or the high water-absorbency material in sheet
form according to this invention comprises pulp fiber, water-soluble resin and
high water-absorbency resin. The compound ratio of the fiber and resin is not
an issue, but in order to raise the water absorbency it is preferable that the
pulp fibers be kept to a small (trace) amount and the water-soluble resin and
high water-absorbency resin be mixed in in a large amount (about ~0%).
Methods for forming the sheet include the above method of mixing pulp
fiber, water-soluble resin and high water-absorbency resin and forming it into
sheet, a method whereby water-soluble paper consisting of pulp-fiber and water-
soluble resin is used to sandwich the high water-absorbency resin, and a method
whereby high water-absorbency resin is bonded to water-soluble paper. There
is also a method wherein sheet formed from the said mi~ture of pulp-fiber,
water-soluble resin and high water-absorbency resin is used to sandwich the high
water-absorbency resin. Compared with the method whereby water-soluble paper
is used to sandwich high water-absorbency resin, this provides an improved
water-absorbency ratio because two high water-absorbency water-soluble sheets
are used. Also, with the method using conventional water-soluble paper to
sandwich the high water-absorbency resin, the finished sheet ;s thick and stiff,
in addition to which ;f the amount of high water-absorbency resin is increased
to raise the water-absorbency ratio, there has been the problem that the sheet
loses resiliency, but with water-soluble paPer containing high water-absorbency
resin resiliency is retained. Ilowever, the water setting (solidifying)
paper (the high water-absorbency sheet) according to this invention may be
formed using any method of manufacture, laminate state or structure, provided it
is in sheet form.
As the high water-absorbency resin for use in this invention, in addition
to natural resins such as starch there may be utili~ed various synthetic resins
produced by the crosslinking of polyacrylic acid, polystyrene sulfonic acid,
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polyvinyl pyridine, maleic anhydride, carboxylmethylcellulose, polyethylene
oxide, polyvinyl aoclhol, or cellulose ether. The high water-absorbency resin
for use in this invention is not however limited to the above ones, which are
examples of existing high water-absorbencY resins; in addition to the above,
any other resin which has high water-absorbency may also be utili~ed.
Also, carboxymethylcellulose (CMC-H) or carboxyethylcellulose (C~C-H) are
often utilized as the water-soluble resin, but the respective aluminum salt,
barium salt, zinc salt, tin salt and manganese salt thereof (C~C-~, CMC-Ba,
CMC-Zn, CMC-Sn, CMC-Mn, CEC-A1, CEC-Ba, CEC-Zn, CEC-Sn, CEC-Mn) may also be
utilized. The water-soluble resin for use in this invention is not however
limited to the above ones, which are examples of existing water-soluble resins;
in addition to the above, any other resin which is water-soluble may also
utilized. ~oreover, if required by an application, paper-making materials
such kraft pulp for paper-making, sulfite pulp, soluble pulp for synthetic
fiber and other such vegetable fibers, polyamide, polyester and other such
synthetic fibers, glass fiber, asbestos and other inorganic fibers may be mixed
in as required up to a proportion which does not impede dispersion and
dissolution in water.
High water-absorbency resins are generally of a grafted-starch system,
cellulose system, or polyacrylic acid system. It is known that when water-
soluble resin is crosslinked, as the density of the crosslinks increases the
nature of the resin changes, from water-solubili-ty to water-growth, and then to
merely lyophilic. Iligh water-absorbency resin is an application of water-
growth resin obtained from low-density crosslinking. That is, high water-
absorbency resin is made by low-density crosslinking of water-soluble resin such
as C~C, PV~, polyacrylic acid soda, starch-acrylic acid graft polymer, starch-
acrylilonitrile graft polymer hydrozylates, and possesses high water-absorbency
and low water-retentivity. Whereas pulp and tissue paper can absorb up to
2D times their own wei~ht of water, high water-absorbency resin can absorb at
least 50 to 500 timeg its own weight of water. Pulp or sponge only forms a
2a~i8
state whereby water is occluded in the ;nternal spaces thereof, so the water is
easily ejected by the application QP external pressure. When high water-
absorbency resin comes into contact with water it reacts chemically, swelling
and gelling, so that once water has been absorbed and it has swollen and jelled,water-retentivity is high, as water does not leak out even when an external
pressure is applied.
High water-absorbency resin possessing these characteristics is sandwiched
in layer form between the said water-soluble resin such as CMC-H and pulp fiber,or the high water-absorbency resin is mixed in during the paper-making process,
to produce the high water-absorbency sheet of this invention. However,
sandwiching the resin between pulp fiber layers involves a problem with regard
to sheet flexibilitY, so there is a limit to the amount of high water-absorbencyresin that is to be thus sandwiched, and accordingly the water-absorbency limit
is 20 times its own weight. Therefore, it is preferable that high water-
absorbency resin be mixed in during the paper-making process, and, if moreover
high water-absorbency resin is sandwiched between sheets produced with high
water-absorbency resin mixed therein it becomes possible to attain the said
water-absorbensy ratio of some 50 to 500 times.
When water setting paper (high water-absorbency sheet~ formed as described
above comes into contact with water or some other aqueous solution, because it
contains the said CMC-H or the like the water setting paper ~hi~h water-
absorbency sheet) first dissolves in the water, and the high water-absorbency
resin contained in the water setting paper (high water-absorbency sheet) or
which has been sandwiched therein dissolves in the water, the reaction starts,
and the water content starts to set, swelling and gelling.
Where there is water content the water setting ~solidifying)paper (high
water-absorbency sheet) dissolves, but dissolution stops when a state of
saturation is reached, leaving the water setting paper (high water-absorbency
sheet) with portions which have dissolved and portions which are still ;n sheet
form. With the next influx of water the portions of the remaining part of
the water setting (water sol;difying) 1paper ~h21g~ wa-ter-absorben(;y sheet)
involved melt, and the high water-absorbency resin contained inside the water
setting paper (higtl water-absorbency sheet) or which has been sandwiched
therein starts reacting, swelli~g and gelling.
Therefore, because unlike the conventional chemlcal agent (po~der) form of
high water-absorbency resin it is in the for~ of a sheet, it elimin~tes the
drawback of underlying particles resulting in the agent setting without the
reaction having taken place fully, so that it is possible to maintain a state
in which additional moisture can be absorbed at any time. This ;s the merit
of the entirely different sheet form, compared with the conventional chemical
agent.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will now be described in detail with reference to
the attached drawings, where
Figure 1 is a perspective view showing the water setting paper (high
water-absorbency sheet) of this invention, in place inside a urine container,
and
Figure ~ is a perspective view of a portable -toilet in which has been
placed the water setting paper ~highly water-absorbent sheet).
DESCRIPTION OF THE PREFERRED EMBODIMENT
The water setting paper (high water-absorbency sheet) merely has to be
placed in the urine container. In the case of the conventional high water-
absorbency resin powder any tilting or shaking of the container could cause the
agent to spill out, but with the water setting paper (high water-absorbency
sheet) according to this invention there is no concern that such tilting or
shaking may cause the inserted sheet to fall out.
When urine is voided into such a container, the paper component containing
the said CMC-H or the like being water-soluble therefore disperses and
dissolves in the urine, and as the water setting paper (high water-absorbency
sheet) dissolves the high water-absorbency resin contained therein is exposed or
281)25il3
is dissolved. Thus, the h;gh water-absorbency agent starts to react,
solidifying the water content, swelling and gelling. ~ovin~ or shaking the
urine container does no-t therefore cause the urine therein to spill, so there
is no soiling of the surroundings. Moreover, if high water-absorbency resin
is placed inside the urine container as it is, irrespective of the amount of
urine all of the resin is wetted, making further use thereof impossible, sothat
each time urination is performed all the resin must be replaced. ~lowever,
when the high water-absorbency resin is formed integrally with paper, as in this
invention, or when the intergrally manufactured sheet is utilized to sandwich
high water-absorbency resin, it still has water-retention capability, which is
to say it retains the sheet form, so re-use is possible and it is economical.
Also, with respect to disposal, the gelled high water-absorbency resin can be
easily washed out with water.
Furthermore, with the high water-absorbency resin reacting with the water
content, solidifying it, the voided urine or the like does not come into contact
with the air, so there is no release of unpleasant odors from the urine.
Thus, with the water setting (solidifying) paper (high water-absorbency
sheet) according to the present invention and formed as described in the
foregoing, by using high water setting paper (water-absorbency sheet) inserted
in a urine container such as a urine bottle or a portable toilet, spillage of
voided urine caused bu moving or shaking the container can be prevented. Also,
as the solidified urine can be flushed down the toilet, disposal of the urine is
simple, quick and hygienic. In addition, the ease with which it can be
handled and its water absorbency and water retentivity enable it to be applied
widely, such as to sanitary napkins and paper diapers and the like.
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