Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
1997-10-14
2002-02-19
Dixon, Merrick (Department: 1774)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C428S220000
Reexamination Certificate
active
06348257
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an antibacterial water absorbing composition having excellent water absorption performance and antibacterial performance. The invention is further directed to absorbing materials particularly for absorbing urine, blood, other body fluids and the like, and to methods of producing the water absorbing composition.
2. Description of the Related Art
Water absorbing resins are widely used in water absorbing materials or water absorbing articles such as disposable diapers, incontinence pads, sanitary napkins, nursing pads, sheets for pets, absorbent materials for pets litter, excretion treating agents, waste blood gelling materials, drip absorbers and freshness retaining materials. The devices rely on the resins for their water absorbing performance, water retention capacities, gelling properties and the like. However, although the conventional water absorbing resin has excellent absorption and retention capacities for urine, blood and other body fluids, the resins do not have antibacterial properties.
Therefore, when the water absorbing resin absorbs urine, blood, and other body fluids and the like, the organic materials contained in the fluids absorbed by the resin are degraded by various fungus and microorganisms, thereby causing, for example, bad odors, skin irritations, and skin rashes. Further, the hydrogels are easily putrefied by the fungus and the microorganisms contained in the fluids being absorbed or the bacteria in the air, and bad odors may develop due to the putrefaction. To avoid these problems and to maintain a hygienic and safe environment, materials which exhibit both absorptive properties and antibacterial properties are desired. In particular, the problems of developing bad odors or rashes are serious in the water absorbing materials such as disposable diapers for the bedridden elderly and the sick. Accordingly, a continuing need exists to solve these problems.
The prior methods for providing absorbing materials with antibacterial properties include methods of spraying a water absorbing resin with an aqueous solution of specific antibacterial component as disclosed in Japanese Kokoku No. 3-14867. Other prior methods include adding an aqueous solution of a specific antibacterial component after mixing a water absorbing resin and an inorganic material together as disclosed in Japanese Kokoku No. 4-17058. The compositions prepared by these methods are proposed for use in water absorbing materials.
Although these prior compositions exhibit some antibacterial function and water absorbing function, they are not necessarily satisfactory for water absorbing materials. For example, in the method of spraying a water absorbing resin with an aqueous solution of a specific antibacterial component, the water absorbing resin easily coagulates and forms lumps when the resin contacts the aqueous solution of the antibacterial agent. Consequently, it is difficult to uniformly mix the water absorbing resin with the solution of an antibacterial component, and it is difficult to obtain a composition with the stabilized antibacterial properties. Furthermore, the spray process requires an evaporating step to remove the excess or other solvent after mixing and grinding and adjusting the particle size of the dried material, thereby complicating the production process.
The process of adding an aqueous solution of a specific antibacterial component to mixtures of a water absorbing resin and an inorganic material also forms lumps as described above, although usually not to the same extent. However, the aqueous solution of the antibacterial component is absorbed in the water absorbing resin and also in the inorganic material, so that the distribution of the antibacterial component becomes non-uniform. This causes large variations in the antibacterial performance of the composition and the material. Further, the increased likelihood of the dust escaping creates environmental concerns. The fine dust particles of the hydrophilic resins is difficult to control and remove from the air. Accordingly, there is a continuing need in the industry for improved methods of producing water absorbing resins with antibacterial properties.
SUMMARY OF THE INVENTION
The present invention is directed to antibacterial water absorbing compositions having excellent water absorption performance and antibacterial performance. The composition of the invention is a free-flowing powder having improved powder handling properties with lower amounts of dust being produced during manufacture. The composition is particularly useful for absorbing urine, blood, body fluids, and the like, and in the manufacture of absorbing materials such as disposable diapers, absorbent pads, sanitary napkins and the like.
The present invention is an antibacterial water absorbing composition comprising a mixture of powders of a water absorbing resin and an antibacterial powder mixture. The antibacterial powder mixture is prepared by allowing fine particles of porous inorganic adsorbent powders to adsorb an aqueous fluid of an antibacterial agent. The antibacterial water absorbing composition is obtained by allowing fine particles of porous inorganic powders to absorb an aqueous fluid of an antibacterial component and then mixing the particles with a particulate water absorbing resin.
Accordingly, a primary object of the invention is to provide an antibacterial water absorbing composition that is easy and economical to manufacture.
Another object of the invention is to provide an antibacterial water absorbing composition that is effective in inhibiting bacterial and fungal growth in aqueous fluids absorbed in the composition.
A further object of the invention is to provide an antibacterial water absorbing composition containing an antibacterial agent adsorbed in an inorganic porous adsorbent powder.
Still further object of the invention is to provide a method of producing an antibacterial water absorbing composition where the composition is produced by adsorbing an aqueous solution of an antibacterial agent in an inorganic porous adsorbent powder.
The objects of the invention are basically attained by providing an antibacterial water absorbing composition comprising a mixture of:
at least one particulate water absorbing resin;
and at least one antibacterial powders comprising at least one particulate inorganic adsorbent powder having adsorbed therein at least one antibacterial agent;
wherein said composition is a substantially free-flowing powder having water absorbing properties, and wherein said antibacterial agent inhibits bacterial growth in aqueous liquids adsorbed by said composition.
The objects of the invention are further attained by providing an antibacterial water absorbing material comprising at least one water absorbing substrate; and at least one water absorbent gel-forming composition, said composition comprising a mixture of a particulate water absorbing resin and an antibacterial powder comprising a particulate inorganic adsorbent powder having adsorbed therein an antibacterial agent.
The objects of the invention are also attained by providing a process for producing an antibacterial water absorbing composition comprising the step of:
mixing a particulate inorganic adsorbent and an aqueous fluid of an antibacterial agent whereby said antibacterial agent is adsorbed by said adsorbent to form an antibacterial powder, and
mixing said antibacterial powder with a particulate water absorbing resin to produce said composition.
These and other objects, advantages and salient features of the invention will become apparent from the detailed description of the invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is directed to a water absorbing composition having antibacterial properties. The composition contains an effective amount of an antibacterial agent to inhibit the growth of bacterial, fungus and other microorganisms in aqueous fluids absorbed in the composition. The invention is further directed to a method of producing the an
Fujita Masahisa
Koike Masanori
Tanaka Kenji
Dixon Merrick
Roylance Abrams Berdo & Goodman L.L.P.
Sanyo Chemical Industries Ltd.
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