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ABSORBENT MAT FOR EXCRETA
This application is a divisional of application Ser. No. 09/758,418, filed on Jan. 12, 2001, now U.S. Pat. No. 6,578,520, the entire contents of which are hereby incorporated by reference and for which priority is claimed under 35 U.S.C. §120; and this application claims priority of Application Nos. 2000-5440; 2000-233448; 2000-283174; and 2000-348550 all filed in Japan on Jan. 14, 2000, Aug. 1, 2000, Sep. 19, 2000, and Nov. 15, 2000, respectively, under 35 U.S.C. §119.
BACKGROUND OF THE INVENTION
The present invention relates to an absorbent mat for treating pet or human excreta and an excreta treating system using the same, particularly a system and a method for treating excreta of pets such as dogs and cats. The present invention also relates to a method of producing a pet excreta treating material, a pet toilet using the same, and a method of treating pet excreta using the same.
Molded granules for treating excreta discharged by pet animals such as cats and dogs and humans which comprise ground natural sand such as silica sand, and a particulate water-absorbing material such as zeolite or an absorbent polymer, are known. However, the granules have disadvantages that they tend to scatter to make surroundings dirty and generate dust during use by a pet or when handled by a pet owner; being amorphous and flowable, they are inconvenient to handle and dispose of; and they are not allowed to be disposed of as combustibles. Absorbent sheets for excreta treatment are also known. For example, Japanese Utility Model Laid-Open No. 1-105448 discloses a deodorizing and bactericidal urine sheet which is a paper-like sheet. The paper-like sheet, however, has poor absorbing capacity and poor strength so that it is inconvenient to handle and dispose of and cannot be used for a long time. Further, molded products for excreta treatment are also required to have a deodorizing effect. Molded products for excreta treatment which have a high deodorizing effect and are free from the above-described disadvantages have not been developed yet.
Japanese Patent Laid-Open No. 7-67489 proposes a bed for treating excreta of pet which has a porous member such as a metal net or a punched metal sheet partitioning the litter box into upper and lower parts, water-repellent litter placed on the porous member, and an absorbent member comprising a water-retentive absorbent polymer placed under the porous member. Urine having passed through the litter is absorbed and retained by the absorbent member.
However, the above bed gives no considerations to the urine which may stay on the porous member. Urine staying on the porous member emanates a pungent and offensive odor. Where the porous member is reinforced with ribs, etc., gaps are made between the porous member and the absorbent member. It tends to follow that liquid waste stays in film form over the entire openings of the porous member and causes an offensive odor. Further, this bed is designed to keep the litter in the upper part always dry by making the lower absorbent member absorb liquid waste. In other words, it chiefly aims at urine treatment. That is, when a pet gets rid of its solid waste, the whole litter must be exchanged for fresh one. In this respect there is no difference from a common litter, still leaving the problems of laboriousness and bad economy.
Japanese Patent Laid-Open No. 9-308403 discloses litter (pellets) prepared by heat compressing softwood sawdust
which self-disintegrates on water absorption. If this litter is used in the above-described bed of Japanese Patent LaidOpen No. 7-67489, it will disintegrate upon absorbing urine, drop through the openings of the porous member, and scatter
5 over the absorbent member. If this happens, it would be much time-consuming to exchange only the litter, and part of the disintegrated litter remains on the porous member to emanate an offensive odor. Besides, the litter must be exchanged each time the litter disintegrates on liquid absorp
SUMMARY OF THE INVENTION
An object of the present invention is to provide an absorbent mat for treating excreta which is excellent in urine 15 absorption properties and deodorizing effect, easy to handle and dispose of, and serviceable for an extended period of time.
Another object of the present invention is to provide an excreta treating system in which urine is prevented from 20 staying on the upper part of the system and from emanating an offensive odor.
Still another object of the invention is to provide an excreta treating system which is handy to exchange and serviceable for a long time.
Yet another object of the invention is to provide an excreta treating system in which both urine and excrement can be treated easily and economically.
The above objects are accomplished by providing an 30 absorbent mat for excreta treatment (hereinafter simply referred to an absorbent mat or, more simply, a mat) having a flat shape and comprising
an absorbing base material comprising at least one of plant fiber and pulp, 35 an antimicrobial surface active agent or a combination of a surface active agent and an antimicrobial agent, and at least one of a binder, a crosslinking agent and water, the absorbent mat having a thickness of 3 mm or greater, a bulk density of 0.05 to 0.3 g/cm3, a saturated water absorp40 tion of 2 g/1 g or more, and a rate of water absorption of 30 sec or shorter.
The present invention also provides an excreta treating system comprising a draining board, the above-described absorbent mat laid under the draining board, and a tray in 45 which the draining board and the mat for excreta treatment are put.
The present invention also provides an excreta treating system comprising a draining board and the absorbent mat laid underneath the draining board, the lower surface of the
50 draining board and the upper surface of the mat are in close contact with each other.
The present invention also provides a method of treating excreta comprising the steps of laying the absorbent mat under a draining board and then allowing the mat to absorb
55 pet liquid waste having been discharged on the draining board and passed through the draining board.
The present invention also provides an excreta treating system for pets comprising a draining board, the absorbent mat laid under the draining board, and an excreta treating
60 material put on the draining board, the excreta treating material comprising molded pieces of prescribed shape and having sufficient shape retention not to disintegrate on water absorption.
The present invention also provides a method of produc65 ing an excreta treating material comprising molded pieces of prescribed shape and having sufficient shape retention not to disintegrate on water absorption, which method comprises
molding a mixture of 70 to 97% by weight of a ground material of plant origin and 3 to 30% by weight of a synthetic resin into pieces of prescribed shape by use of a sprout molding machine.
The present invention also provides a pet toilet compris- 5 ing a tray, the absorbent mat put in the tray, and liquid permeable nonwoven fabric covering the entire upper surface of the absorbent mat, the nonwoven fabric being fastened at prescribed positions so as to come into close contact with the upper surface of the absorbent mat. 10
The present invention also provides a method of treating pet excrement which uses the pet toilet, in which the nonwoven fabric is unfastened after a pet gets rid of its solid waste, rolling up the nonwoven fabric with the waste inside, and disposing of the nonwoven fabric together with the 15 waste.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be more particularly described with reference to the accompanying drawings, in which:
FIG. 1 is a perspective showing usage of the absorbent mat according to the present invention;
FIG. 2 schematically illustrates a method of measuring the saturated water absorption of an absorbent mat according 25 to the invention;
FIG. 3 schematically illustrates a method of measuring the wet strength of an absorbent mat according to the invention;
FIG. 4 is a schematic illustration showing an embodiment 30 of the excreta treating system according to the present invention;
FIGS. 5A and 5B are a plan view and a cross-sectional view, respectively, of the draining board used in FIG. 4; 3J
FIG. 6A, FIG. 6B, FIG. 6C and FIG. 6D each present a typical cross-sectional contour of the parts surrounding through-holes of the draining board used in FIG. 4;
FIG. 7 is a perspective of an embodiment of the pet toilet according to the invention, with part of which is cut away; 40
FIG. 8 is an exploded perspective view of part of the pet toilet shown in FIG. 7; and
FIG. 9 shows another usage of the pet toilet shown in FIG.
DETAILED DESCRIPTION OF THE
The present invention will be described with particular reference to its preferred embodiments and the accompany- 50 ing drawings. As shown in FIG. 1, an absorbent mat 1 according to one embodiment of the invention is in a flat shape having some thickness with flat surfaces on its both upper and lower surfaces. The mat 1 is a molded article obtained by molding a mixture of (1) an absorbing base 55 material, (2) an antimicrobial surface active agent or a combination of a surface active agent and an antimicrobial agent, and (3) at least one of a binder, a crosslinking agent, and water.
The absorbing base material comprises at least one of 60 plant fiber and pulp. The mat molded from a mixture comprising plant fiber as a main component is not only porous and sparse (low density) to show excellent absorptivity for liquid but also effective in deodorization. Being combustible, it can be disposed of for incineration. The term 65 "plant fiber" as used herein means fiber that constitutes plants or an aggregate thereof Plant fiber comprises not only
cellulose but lignin, hemicellulose, a resinous component, ash, and others. The term "pulp" as used herein means plant fiber substantially freed of the components other than cellulose to have a high cellulose purity. So called chemical pulp corresponds to the "pulp".
The plant fiber includes groundwood pulp, sawdust, jute, and palm fiber. These fibers can be used either individually or as a mixture thereof From the standpoint of absorptivity, deodorizing effect, and stable supply, groundwood pulp and/or sawdust are particularly preferred. The term "groundwood pulp (GP)" as used herein is intended to include not only groundwood pulp in the narrow sense of the word but other kinds of mechanical pulp, such as stone ground pulp (SGP), refiner ground pulp (RGP) and thermomechanical pulp (TMP). Of these groundwood pulp kinds stone ground pulp is particularly preferred for its deodorizing action. The pulp may be either of softwood or hardwood. Pulp of German spruce is preferred. It is preferable to use pulp of wastepaper, which is preferably de-inked for securing absorptivity. The plant fiber and the pulp can be used as an absorbing base material either individually or as a mixture thereof. When used as a mixture, the plant fiber and the pulp are mixed at a weight ratio of 10:1 to 1:100.
It is preferred for the absorbent mat according to the invention to contain 50 to 95% by weight, particularly 70 to 90% by weigh, of the absorbing base material (the plant fiber and/or the pulp) for necessary strength as well as improved absorptivity and deodorizing effect.
The absorbent mat 1 contains an antimicrobial or nonantimicrobial surface active agent to have increased hydrophilic properties and an increased rate of absorption for urine, etc. The presence of the surface active agent as well as the low density and the porosity make the absorbent mat 1 exhibit a high water absorption and a high rate of water absorption as hereinafter described.
Where the surface active agent has antimicrobial action, growth of microorganisms, which decompose excreta to generate ammonia, in the absorbent mat 1 can be controlled so that the mat can be used for an extended period of time without emanating a pungent odor. Where the surface active agent has no antimicrobial effect, it is used in combination with an antimicrobial agent to produce the same effects.
The antimicrobial surface active agents which can be used include cationic ones and amphoteric ones. Useful cationic surface active agents having antimicrobial activity include an alkyltrimethylammonium chloride, a dialkyldimethylammonium chloride, and benzalkonium chloride, and mixtures of two or more thereof, with benzalkonium chloride being preferred for its antimicrobial effect. Useful amphoteric surface active agents having antimicrobial activity include an alkyldimethylaminoacetic acid betaine, an alkyldimefhylamine oxide, an alkylcarboxymethylhydroxyethylimidazolinium betaine, an alkylamidopropyl betaine, and mixtures of two or more thereof, with an alkyldimefhylamine oxide being preferred for its antimicrobial and deodorizing effects. If desired, the antimicrobial surface active agent can be used in combination with an antimicrobial agent to further ensure the antimicrobial activity of the mat 1. In this case, the antimicrobial agent to be combined is preferably water soluble.
To secure the improvement in absorptivity and the prevention of odor generation thereby to guarantee long serviceability, it is preferred for the absorbent mat 1 to contain 0.1 to 5% by weight, particularly 0.5 to 3% by weight, of the antimicrobial surface active agent.
The surface active agents having no antimicrobial activity include nonionic surface active agents, such as glycerol fatty
acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkyl ethers, polyoxyethylene glycol fatty acid esters, and mixtures of two or more thereof. From the standpoint of water solubility, those having an HLB of 10 to 19 as calculated by a BLB- 5 numerical system are preferred. The antimicrobial agents which can be used in combination with the nonantimicrobial surface active agent are preferably watersoluble and include sodium benzoate, chloramine T, chlorocresol, sodium salicylate, ethyltrimethylammonium 10 bromide, potassium sorbate, sodium dehydroacetate, p-chlorophenol, phenol, and mixtures of two or more thereof Sodium benzoate is preferred from the viewpoint of odor and safety to animals.
It is preferred for the absorbent mat 1 to contain 0.01 to 15 5% by weight, particularly 0.1 to 5% by weight, especially 0.1 to 2% by weight, of the non-antimicrobial surface active agent together with 0.001 to 5% by weight, particularly 0.1 to 0.5% by weight, of the antimicrobial agent.
The binder, crosslinking agent or water is used as a means 20 for binding the individual plant fibers and/or the individual pulp fibers (hereinafter these components will be inclusively referred to as an interfibrous binder). The interfibrous binder makes the absorbent mat 1 strong enough for practical use, easy to handle and dispose of, and durable for a long time. 25
The crosslinking agent serves to crosslink the fibers through a hydrogen bond and is suitably used in cases where the absorbent mat is produced by a wet process hereinafter described. The term "binder" as used herein is intended to mean an adhesive (a substance that can be used to make two solids, either of the same or different kinds, stick together) except the above-mentioned crosslinking agents.
The binders which can be used include polyvinyl alcohol, processed starch, agar, carboxymethyl cellulose, 3J polyacrylamide, and mixtures of two or more thereof Polyvinyl alcohol and/or processed starch are preferred for their water absorptivity. It is preferred for the polyvinyl alcohol and the processed starch to have a gelatinization temperature of 60° C. or higher, particularly 70 to 80° C, so as not to 4Q dissolve in the absorbent mat after use (i.e., in the wet state) at room temperature. Thus, the mat has a constant wet strength and is always easy to handle and dispose of, being prevented from shape disintegration. The binder is preferably used in an amount of 1 to 45% by weight, particularly 4J 5 to 45% by weight, especially 7 to 20% by weight, based on the mat 1.
Substances commonly used in wet papermaking as a strengthening agent can be used as the crosslinking agent. Such crosslinking agents include polyamidoamine epichlo- 50 rohydrin resins, polyacrylamide, polyethylene, mefhylolated polyacrylamide, and mixtures thereof. These crosslinking agents can be used as an interfibrous binder either alone or in combination with water as a medium. The crosslinking agent is preferably used in an amount of 0.01 to 3% by 55 weight, particularly 0.3 to 1% by weight, based on the mat 1.
Where the absorbent mat 1 contains water as a sole interfibrous binder, a preferred water content of the absorbent mat 1 is 1 to 20% by weight, particularly 5 to 20% by 60 weight.
If desired, the absorbent mat 1 can further contain additives, such as a deodorizing agent or a masking agent, in addition to the above-mentioned components (i.e., the absorbing base material, the antimicrobial or non- 65 antimicrobial surface active agent, the antimicrobial agent, and the interfibrous binder). A suitable amount of the addi
tives ranges from 0.01 to 1% by weight, particularly from 0.03 to 0.1% by weight.
The absorbent mat 1 is a flat plate having a thickness of 3 mm or greater, preferably 5 to 50 mm, still preferably 10 to 20 mm, molded out of a mixture comprising the abovedescribed essential components and necessary additives. Compared with a paper-like sheet, the mat with a certain thickness has a higher water absorption capacity and higher strength. Unlike granular litter, the mat produces little dust when handled and is easy to dispose of.
The thickness of the absorbent mat is an average of thicknesses measured with a microgauge at 10 cm intervals in the width direction.
The absorbent mat 1 has a bulk density of 0.05 to 0.3 g/cm3, preferably 0.1 to 0.25 g/cm3, still preferably 0.15 to 0.2 g/cm3. As far as the bulk density of the mat falls within this range, the mat exhibits an increased rate of absorption while retaining sufficient strength for use. Having such a low density and being porous, the absorbent mat is expected to release the water content of liquid waste once absorbed therein under a low humidity environment. Therefore, it is capable of absorbing liquid waste more than expected from the experimentally determined water absorption hereinafter described.
The bulk density (g/cm3) of the mat is obtained by weighing a 6 cm wide, 6 cm long and 1 cm thick piece cut out of the mat and dividing the weight (g) by the volume of the cut piece (36 cm3).
The absorbent mat 1 exhibits excellent absorption performance for liquid such as urine, having a saturated water absorption of 2 g/1 g or more, preferably 5 g/1 g or more, still preferably 8 g/1 g or more, and a rate of water absorption of 30 sec or shorter, preferably 10 sec or shorter, still preferably 3 sec or shorter. Such a high rate of water absorption effectively prevents the four limbs of a pet from getting wet with its own liquid waste. The upper limits of the saturated water absorption and the rate of water absorption are not limited and desirably as high as possible, but would be practically about 5 g/1 g and about 1 sec, respectively.
The saturated water absorption is measured as follows by use of a demand wettability tester shown in FIG. 2, which is well known as an apparatus for carrying out a demand wettability (DM) test. A 60 mm wide and 60 mm long specimen is cut out of the mat without changing its thickness, dried in a drier set at 105° C. for 1 hour, and then allowed to cool to room temperature in a desiccator. The thus conditioned specimen is put on a glass filter set on the same level with the liquid level of physiological saline in the burette as shown in FIG. 2. The three-way cock is opened to let the specimen absorb physiological saline. When bubbling in the burette stops, the scale of the burette which indicates the reduction of physiological saline in amount is read and divided by the weight of the specimen to obtain the amount of water (g/g) absorbed to saturation. The measurement was made on three specimens per sample (n=3) to obtain an average.
The rate of water absorption is measured as follows. A 60 mm wide and 60 mm long specimen is cut out of the mat without changing its thickness, dried in a drier set at 105° C. for 1 hour and then allowed to cool to room temperature in a desiccator. In the center of the thus conditioned specimen is dropped 2.5 cc of physiological saline, and the time required for the liquid immediately after dropped to be absorbed by the specimen is obtained as a rate of water absorption (sec). The measurement was made on three specimens per sample (n=3) to obtain an average.