Underwear abstract
Compositions which greatly diminish, or eliminate, unpleasant smells
associated with the use of underwear and diapers are described.
These compositions are composed of superabsorbent polymers of the
polyacrylic type and of certain boron derivatives, in particular
sodium tetraborate. The sanitary articles which incorporate these
compositions do not develop unpleasant smells, ammoniacal or otherwise.
Underwear claims
We claim:
1. A process for the production of a superabsorbent composition
intended for the production of sanitary articles selected from the
group consisting of underwear, diapers and disposable diapers, wherein
the articles do not develop unpleasant smells, wherein the process
comprises
polymerizing with partial crosslinking, water-soluble ethylenically
unsaturated monomers to form a polymeric product;
swelling said polymeric product with an aqueous solution of a boron
derivative said boron derivative selected from the group consisting
of anhydrous sodium tetraborate, sodium tetraborate pentahydrate,
sodium tetraborate decahydrate, and sodium metaborate of any degree
of hydration; and
removing excess water by evaporation.
2. A process for the production of a superabsorbent composition
intended for the production of sanitary articles selected from the
group consisting of underwear, diapers and disposable diapers, wherein
the articles do not develop unpleasant smells, wherein the process
comprises
polymerizing with partial crosslinking, water-soluble ethylenically
unsaturated monomers to form a polymeric product; and
mixing with said polymeric product a borate selected from the group
consisting of sodium tetraborate or sodium metaborate, in the proportion
0.1 to 10% by weight of borate, with respect to the superabsorbent
composition.
Underwear description
The invention relates to the production of sanitary articles intended
to absorb and retain body fluids.
When the absorbing article in place is impregnated with such body
fluids, in particular urine, powerful and unpleasant smells are
produced. The predominant smells among these are ammoniacal smells
due to the ammonia originating from the hydrolysis of urea by the
ureases of bacteria (Proteus, Acinetobacter, and the like) present
on the skin and in the digestive tract.
For the purpose of suppressing these smells, widespread recourse
has been had to absorbents of smells or ammonia (U.S. Pat. No. 3,340,875,
Scott Paper Company), optionally in combination with deodorants,
fragrances, and the like. The use of pH buffers (WO-A-94 25077),
of oxidants (hydrogen peroxide, chlorine dioxide), of biocides (metals
or of metal cations), as well as of bactericides (quaternary ammoniums,
in particular), of antibiotics, of complexing agents or of surfactants,
both alone and in combination with one another, has also been recommended.
These various products present the general problem of an irritant
effect on the skin and mucosal mebranes. Absorbents of smells or
of ammonia are certainly less dangerous in this respect but they
leave the field free for a bacterial growth which remains worrying
and which it would be advisable to control from the outset. The
way which appeared necessary for the control of the bacterial emission
of ammonia from urea consists in inhibiting the enzymes which are
responsible for it, that is to say the ureases.
The use of urease inhibitors of low or moderate activity has until
now only been envisaged in combination with ammonia scavengers (JP
61-179155). Some powerful urease inhibitors, such as hydroxamic
acid derivatives (U.S. Pat. No. 3,920,015, Allied Chem. Corp.),
are advantageous but their toxicity excludes them from the targeted
use. Others, such as phenyl phosphorodiamidate (PPDA) or dimethyldithiocarbamate
(DTC), are compounds which are very effective against the formation
of ammonia but give rise, during their use, to other very unpleasant
sulfurous or alliaceous smells which are perhaps related, at least
in part, to their own decomposition by the bacterial flora present.
The search for a solution to this problem is all the more pressing
since, nowadays, the absorption capacity for body fluids of protection
articles has been very substantially increased by incorporating
superabsorbent polymers (SAP) into them, in particular hydrophilic
polymers and copolymers of acrylic acid, and since, by the same
token, the time during which they are maintained in place has been
increased, all conditions which promote the development of microbial
and enzymatic activity and of the smells which result therefrom.
It has now just been found that it is possible to formulate superabsorbent
polymers with certain boron derivatives in order to prepare therefrom
compositions which, although impregnated with urine or with biological
fluids containing it and maintained under conditions of use which
are especially propitious for bacterial growth, give rise neither
to significant evolution of ammonia nor to repellent or simply unpleasant
smells and which communicate this property to the sanitary articles
which contain them.
The invention thus consists of a superabsorbent composition intended
for production of sanitary articles of the underwear, diaper or
disposable diaper type which do not develop unpleasant smells which
comprises a polymer, which is superabsorbent with respect to water,
saline solutions and body fluids, and sodium tetraborate or sodium
metaborate in the proportion of 0.1 to 10% of boron derivative,
preferably 0.5 to 5%, with respect to the superabsorbent composition.
Superabsorbent polymers within the meaning of the present invention
are polymers which result from the polymerization, with partial
crosslinking, of watersoluble ethylenically unsaturated monomers,
in particular acrylic and methacyrlic acids and their alkaline salts,
whether they are obtained by an inverse suspension or solution polymerization
process. These polymers possess a very high capacity for absorption
and retention of water and aqueous solutions and are nowadays widely
available commercially in the form of powders with particle sizes
of between 100 and 800 .mu.m. The literature relating to them is
very extensive; reference may be made, for example, to EP-A-0,312,952
(The Dow Chem. Co.) and to EP-A-0,441,507 (Sumitomo Seika Chem.).
Within the meaning of the present invention, sodium tetraborate
(Na.sub.2 B.sub.4 O.sub.7) is the anhydrous, pentahydrate or decahydrate
(borax) salt and the metaborate (NaBO.sub.2) is also regarded independently
of its degree of hydration. These boron compounds are mixed with
the polymer in the powder form in proportions indicated above.
The preparation of the composition according to the invention is
very easy, since it is sufficient to incorporate the boron derivative
in the powder form, preferably with a particle size also of between
100 and 800 .mu.m, in the superabsorbent polymer powder by simple
mixing. However, it has been observed that, if the boron derivative
was introduced within the superabsorbent polymer particles, an odor-preventing
efficiency was obtained, at equivalent concentration, which is greater
than by simple mixing of the powders. This results in an alternative
form of the process, which also forms part of the invention, whereby
the polymer powder is swollen using an aqueous solution of boron
derivative and then the water thus introduced is evaporated.
The superabsorbent compositions of the invention become gelled
on contact with water, aqueous saline solutions or body fluids,
like the superabsorbents of the prior art, and the gels thus formed
behave in a substantially identical way. They do not suffer from
any counterindication, the boron derivatives which are the means
of the invention being rightly regarded as inoffensive and being
widely used in various mild antiseptic compositions at contents
of the order of 1% by weight. They are used in place of the ordinary
superabsorbents in the manufacture of sanitary articles such as
disposable diapers for babies, for young children, for adults or
for elderly people of both sexes. This use also constitutes a subject
of the present invention.
Assessment of the true effectiveness of odor-preventing products
is difficult to carry out. Since the invention comes within the
context of urease inhibitors, the candidate compounds which can
be envisaged for their anti-urease activity are therefore generally
classified by an IC.sub.50 value according to the results of an
enzymatic test which will be described later. Since the process
which generates smells is a biological process, it is necessary
to be able to estimate the effectiveness of various urease inhibitors
for their ability to limit the biological emission, by urea-fermenting
microorganisms, of at least the most common odorous compound, in
this case ammonia. This effectiveness is understood of the inhibitor
just as it is or in the presence of various substances with which
it is combined in the production of diapers and other sanitary articles,
in particular superabsorbent polymers. The results of this test
correlate fairly well with the IC.sub.50 values. Finally and particularly,
it is necessary to be able to decide on the satisfactory overall
result by olfactive tests under conditions which give acceptable
simulation of the conditions of use of the products in which the
superabsorbent composition which is believed to inhibit smells is
incorporated. They are carried out by impregnating a disposable
diaper with urine under standardized conditions, by heating the
combination in an oven at a low temperature and by subjecting the
object to a nose panel for overall assessment of its possible unpleasant
smells. |