Patent Publication Number: US-2022225591-A1

Title: Excrement treatment material and method for manufacturing the same

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This is a Continuation-in-part of International Application No. PCT/JP2020/039823 filed Oct. 23, 2020, which claims the benefit of Japanese Application No. 2019-228797 filed Dec. 19, 2019. The contents of these applications are hereby incorporated by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates to an excrement treatment material and a method for manufacturing the same. 
     BACKGROUND ART 
     A conventional excrement treatment material is disclosed in, for example, Patent Document 1. The excrement treatment material disclosed in Patent Document 1 is an excrement treatment material for animals, and composed of a plurality of grains. Each of the grains is a water absorbing grain that absorbs urine. As shown in  FIG. 4 , an excrement treatment material  90  configured in this way is used in a state in which a plurality of grains  92  are piled in a box-shaped toilet  94 . 
     CITATION LIST 
     Patent Document 
     Patent Document 1: JP 2007-190026 A 
     SUMMARY OF INVENTION 
     Technical Problem 
     In the toilet  94 , urine  96  is excreted from above the excrement treatment material  90 . Therefore, the urine  96  is absorbed mainly by the grains  92  located in the uppermost layer of the excrement treatment material  90  (the black-painted grains  92  in  FIG. 4 ). For that reason, it follows that most of the excreted urine  96  stays in the vicinity of the upper surface of the excrement treatment material  90 . If the urine  96  stays in the vicinity of the upper surface of the excrement treatment material  90  in this way, an odor generated from the urine  96  becomes likely to be released outside the toilet  94 . 
     Solution to Problem 
     The present invention has been made in view of the above-described problem, and it is an object thereof to provide an excrement treatment material that can restrain release of an odor generated from excreted urine, and a method for manufacturing the same. 
     An excrement treatment material according to the present invention is composed of a plurality of grains that are piled in a box-shaped toilet and have a water absorbing property. The plurality of grains include a first grain that absorbs urine excreted in the toilet, and a second grain that absorbs the urine. A water absorption rate of the second grain is smaller than a water absorption rate of the first grain. 
     This excrement treatment material is provided with the first and second grains. The water absorption rate of the second grain is smaller than the water absorption rate of the first grain. Reducing the water absorption rate of the second grain in this way makes it easier for excreted urine to be guided downward in the toilet. For this reason, urine can be dispersed widely in the depth direction of the toilet, compared to a case where only the first grain is provided. Dispersing urine in the depth direction in this way leads to reducing the ratio of urine that stays in the vicinity of the upper surface of the excrement treatment material. Thus, an odor generated from the urine can be restrained from being released outside the toilet. 
     A method for manufacturing an excrement treatment material according to the present invention is a method for manufacturing an excrement treatment material composed of a plurality of grains that are piled in a box-shaped toilet and have a water absorbing property. The method includes: a first grain forming step of forming a first grain that absorbs urine excreted in the toilet; and a second grain forming step of forming a second grain that absorbs the urine. In the second grain forming step, the second grain is formed such that a water absorption rate of the second grain is smaller than a water absorption rate of the first grain. 
     In this manufacturing method, the first and second grains are formed. The water absorption rate of the second grain is smaller than the water absorption rate of the first grain. Reducing the water absorption rate of the second grain in this way makes it easier for excreted urine to be guided downward in the toilet in the manufactured excrement treatment material. For this reason, urine can be dispersed widely in the depth direction of the toilet, compared to a case where only the first grain is formed. Dispersing urine in the depth direction in this way leads to reducing the ratio of urine that stays in the vicinity of the upper surface of the excrement treatment material. Thus, an odor generated from the urine can be restrained from being released outside the toilet. 
     Advantageous Effects of Invention 
     According to the present invention, it is possible to implement an excrement treatment material that can restrain release of an odor generated from excreted urine, and a method for manufacturing the same. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic view showing an embodiment of an excrement treatment material according to the present invention. 
         FIG. 2  is a schematic view showing a grain  10 . 
         FIG. 3  is a schematic view showing a grain  20 . 
         FIG. 4  is a diagram for illustrating a problem of the conventional excrement treatment material. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements are given the same reference numerals, and a redundant description will be omitted. 
       FIG. 1  is a schematic view showing an embodiment of an excrement treatment material according to the present invention. An excrement treatment material  1  is an excrement treatment material used for treatment of excrement (particularly urine) of humans or animals, and composed of a plurality of grains that are piled in a box-shaped toilet and have a water absorbing property. The excrement treatment material  1  includes a grain  10  (first grain) and a grain  20  (second grain). That is, the plurality of grains constituting the excrement treatment material  1  include the grain  10  and the grain  20 . 
     The grain  10  and the grain  20  have a water absorbing property, and absorb urine excreted in the toilet. The grain  10  having the water absorbing property requires the water absorption rate of 40% or more measured by the following test. First, approximate 50 grams of a plurality of the grains  10  (sample) are placed in a strainer. An empty beaker is set under the strainer. Then, 30 ml of water is dripped on the sample over 10 seconds using a syringe without a needle. After waiting 1 minute, the quantity of the water in the beaker is measured. The ratio of the value obtained by subtracting the measured water quantity from the quantity of the dripped water (30 ml) with respect to the quantity of the dripped water shall be the water absorption rate. That is, if the water quantity in the beaker is 18 ml or less, the water absorption rate is 40% or more, and therefore the grain  10  is found to have the water absorbing property. The same shall apply to the grain  20 . 
     The water absorption rate of the grain  20  is smaller than the water absorption rate of the grain  10 . When the water absorption rate of the grain  10  is A % and the water absorption rate of the grain  20  is B %, (A−B)≥10 is preferably satisfied, and (A−B)≥20 is more preferably satisfied. The water absorption rate of the grain  10  is, for example, between 70% and 100% inclusive. The water absorption rate of the grain  20  is, for example, between 40% and 70% inclusive. 
     A plurality of the grains  10  and a plurality of the grains  20  are provided. In the excrement treatment material  1 , the grains  10 ,  20  are provided in a mixed manner. The number of the grains  20  is preferably between 30% and 70% inclusive of the total number of the grains  10  and the grains  20 , and more preferably between 40% and 60% inclusive. The particle diameter of the grain  20  is larger than the particle diameter of the grain  10 . As used herein, the particle diameter is defined as the diameter of the minimum sphere that can include the grain. The particle diameter of the grain  10  is, for example, between 3 mm and 10 mm inclusive. The particle diameter of the grain  20  is, for example, between 5 mm and 15 mm inclusive. 
       FIG. 2  is a schematic view showing the grain  10 . The grain  10  takes in urine to retain it in the inside of the grain  10 . The grain  10  has a core portion  12  (first granule) and a coating portion  14  (first coating portion). The core portion  12  is granulated in a granular shape. Examples of the granular shape include a sphere, column, and ellipsoid. The core portion  12  has a function of absorbing and retaining urine. The core portion  12  contains a water-absorbent material. The core portion  12  contains the water-absorbent material as its main material. As used herein, the main material of the core portion  12  refers to the material that accounts for the highest weight ratio in the core portion  12 , out of one or more materials constituting the core portion  12 . The core portion  12  may be composed only of the water-absorbent material, or may be composed of the water-absorbent material and another material. The water-absorbent material is preferably an organic substance. As the water absorbent material that is an organic substance, for example, papers, used tea leaves, plastics, or bean curd lees can be used. In the present embodiment, the core portion  12  does not contain an adhesive material. 
     The papers refer to a material composed mainly of pulp. Examples of the papers include, in addition to ordinary paper, a vinyl chloride wallpaper classified product (paper obtained by classifying vinyl chloride wallpaper), fluff pulp, papermaking sludge, and pulp sludge. As the plastics, for example, a disposable diaper classified product (plastic obtained by classifying disposable diapers) may be used. The bean curd lees are preferably dried bean curd lees. 
     The coating portion  14  covers the core portion  12 . The coating portion  14  may cover the entire surface of the core portion  12 , or may cover only a part of the surface of the core portion  12 . The coating portion  14  has a function of bonding the grains  10 ,  20  that have absorbed urine to agglomerate them when in use. The coating portion  14  also contains a water-absorbent material as its main material. The definition of the main material of the coating portion  14  is the same as the definition of the main material of the core portion  12 . The water-absorbent material contained in the coating portion  14  is also preferably an organic substance. The coating portion  14  contains an adhesive material. As the adhesive material, for example, starch, CMC (carboxymethyl cellulose), PVA (polyvinyl alcohol), dextrin, or a water-absorbent polymer can be used. 
       FIG. 3  is a schematic view showing the grain  20 . The grain  20  takes in urine to retain it in the inside of the grain  20 . The grain  20  has a core portion  22  (second granule) and a coating portion  24  (second coating portion). The core portion  22  is granulated in a granular shape. The core portion  22  has a function of absorbing and retaining urine. The core portion  22  contains a water-absorbent material. The core portion  22  contains the water-absorbent material as its main material. The definition of the main material of the core portion  22  is the same as the definition of the main material of the core portion  12 . The core portion  22  may be composed only of the water-absorbent material, or may be composed of the water-absorbent material and another material. The water-absorbent material is preferably an organic substance. The core portion  22  may be made of a material that has the same composition as the core portion  12 , or may be made of a material that has different composition from the core portion  12 . In the present embodiment, the core portion  22  does not contain an adhesive material. 
     The coating portion  24  covers the core portion  22 . The coating portion  24  may cover the entire surface of the core portion  22 , or may cover only a part of the surface of the core portion  22 . The coating portion  24  has a function of bonding the grains  10 ,  20  that have absorbed urine to agglomerate them when in use. The coating portion  24  also contains a water-absorbent material as its main material. The definition of the main material of the coating portion  24  is the same as the definition of the main material of the core portion  12 . The water-absorbent material contained in the coating portion  24  is also preferably an organic substance. The coating portion  24  contains an adhesive material. In the present embodiment, the coating portion  24  is made of a material that has the same composition as the coating portion  14 . The thickness of the coating portion  24  may be equal to or different from the thickness of the coating portion  14 . In the case where the thickness of the coating portion  24  is different from the thickness of the coating portion  14 , the thickness of the coating portion  24  may be larger or smaller than the thickness of the coating portion  14 . 
     Next, an example of a method for manufacturing the excrement treatment material  1  will be described as an embodiment of the method for manufacturing an excrement treatment material according to the present invention. The manufacturing method includes a first grain forming step, and a second grain forming step. 
     The first grain forming step is a step of forming the grain  10 . This step includes a first granulating step, and a first coating step. The first granulating step is a step of forming the core portion  12  that constitutes the grain  10 . In this step, the core portion  12  is formed by granulating a first core portion material (material(s) constituting the core portion  12 ) with a granulation apparatus. In the present embodiment, a plurality of the core portions  12  are formed. As the granulation apparatus, for example, an extrusion granulator can be used. Prior to the granulation, the first core portion material is subjected to pretreatment such as pulverization, kneading, and adding water, as needed. 
     The first coating step is a step of forming the coating portion  14 . In this step, the coating portion  14  is formed by attaching a powdery first coating material (materials constituting the coating portion  14 ) to the surface of each core portion  12  with a coating apparatus or the like. The first coating material contains the adhesive material. The first coating material may be attached by, for example, sprinkling or spraying the first coating material. Thus, the plurality of grains  10  are obtained. 
     The second grain forming step is a step of forming the grain  20 . This step includes a second granulating step, and a second coating step. The second granulating step is a step of forming the core portion  22  that constitutes the grain  20 . In this step, the core portion  22  is formed by granulating a second core portion material (material(s) constituting the core portion  22 ) with a granulation apparatus. The second core portion material may have the same composition as the first core portion material, or may have different composition from the first core portion material. In the present embodiment, a plurality of the core portions  22  are formed. As the granulation apparatus, for example, an extrusion granulator can be used. Prior to the granulation, the second core portion material is subjected to pretreatment such as pulverization, kneading, and adding water, as needed. 
     The second coating step is a step of forming the coating portion  24 . In this step, the coating portion  24  is formed by attaching a powdery second coating material (materials constituting the coating portion  24 ) to the surface of each core portion  22  with a coating apparatus or the like. The second coating material contains the adhesive material. In the present embodiment, the second coating material has the same composition as the first coating material. The second coating material may be attached by, for example, sprinkling or spraying the second coating material. Thus, the plurality of grains  20  are obtained. 
     In the second grain forming step, the grain  20  is formed such that the water absorption rate of the grain  20  is smaller than the water absorption rate of the grain  10 . For example, the water absorption rate of the grain  20  can be made smaller than the water absorption rate of the grain  10  by using a material that has a lower water absorbing property than the first core portion material as the second core portion material. Also, the water absorption rate of the grain  20  can be made smaller than the water absorption rate of the grain  10  by making the pressure applied to the second core portion material in the granulation of the core portion  22  higher than the pressure applied to the first core portion material in the granulation of the core portion  12 . That is because gaps on the surface or in the inside of a granule decrease and therefore it becomes hard for the granule to take in urine, if the pressure in granulation is made higher. The pressure in granulation can be adjusted by, for example, changing the thickness of a die of the granulation apparatus. Specifically, the larger the thickness of a die is, the higher the pressure in granulation can be made. 
     Note that the first and second granulating steps may be performed in arbitrary order. That is, the both steps may be performed simultaneously in parallel, or either step may be performed prior to the other step. Similarly, the first and second coating steps may be performed in arbitrary order. 
     After that, the grains  10  formed in the first grain forming step and the grains  20  formed in the second grain forming step are mixed. At this time, it is preferable to mix the grains  10  and the grains  20  such that the number of the grains  20  is between 30% and 70% inclusive of the total number of the grains  10  and the grains  20 . Also, it is more preferable to mix the grains  10  and the grains  20  such that the number of the grains  20  is between 40% and 60% inclusive of the total number of the grains  10  and the grains  20 . Accordingly, the excrement treatment material  1  that includes the grains  10  and the grains  20  in a mixed manner is obtained. 
     The effects of the present embodiment will be described. In the present embodiment, the grain  10  and the grain  20  are formed. The water absorption rate of the grain  20  is smaller than the water absorption rate of the grain  10 . Reducing the water absorption rate of the grain  20  in this way makes it easier for excreted urine to be guided downward in the toilet due to the ratio of urine that is not absorbed by the grain  20  increasing in the excrement treatment material  1 . For this reason, urine can be dispersed widely in the depth direction of the toilet, compared to the case where only the grain  10  is formed. Dispersing urine in the depth direction in this way leads to reducing the ratio of urine that stays in the vicinity of the upper surface of the excrement treatment material  1 . Thus, an odor generated from the urine can be restrained from being released outside the toilet. 
     Moreover, the grain  10  and the grain  20  both have a water absorbing property. Using water absorbing grains for both of the grain  10  and the grain  20  in this way can enhance water absorbability of the excrement treatment material  1  as a whole, compared to a case where a non-absorptive grain is used for either one of the grain  10  or the grain  20 . Thus, it is possible to make a situation less likely to occur in which urine is not absorbed by the grain  10  or the grain  20  and thereby accumulates in the toilet. 
     The smaller the water absorption rate of the grain  20  is, the more easily urine is guided downward in the toilet. On the other hand, the larger the water absorption rate of the grain  10  is, the higher the water absorbability of the excrement treatment material  1  as a whole can become. From this viewpoint, when the water absorption rate of the grain  10  is A % and the water absorption rate of the grain  20  is B %, (A−B)≥10 is preferably satisfied, and (A−B)≥20 is more preferably satisfied. 
     It is advantageous that the grains  20  account for high ratio in the entire excrement treatment material  1  for making urine easier to guide downward in the toilet. From this viewpoint, the number of the grains  20  is preferably 30% or more of the total number of the grains  10  and the grains  20 , and more preferably 40% or more. On the other hand, if the ratio of the grains  20  is too high, absorption of urine by the grains  10  may be insufficient. From this viewpoint, the number of the grains  20  is preferably 70% or less of the total number of the grains  10  and the grains  20 , and more preferably 60% or less. 
     The smaller the particle diameter of a grain is, the more easily the grain moves downward through gaps between other grains. For that reason, in a case where grains having a relatively large particle diameter and grains having a relatively small particle diameter are poured into a toilet in a state of being mixed randomly, the former grains tend to be more likely to be disposed in the upper layer. Therefore, it becomes easy to dispose a lot of the grains  20  in the vicinity of the upper surface of the excrement treatment material  1  by making the particle diameter of the grains  20  larger than the particle diameter of the grains  10 . This is advantageous for reducing the ratio of urine that stays in the vicinity of the upper surface of the excrement treatment material  1 . 
     In the case where the core portion  12  and the core portion  22  are made of materials that have the same composition, it is possible to use the same core portion material as the core portion material for forming the core portion  12  (the first core portion material) and the core portion material for forming the core portion  22  (the second core portion material). This contributes to reduction in manufacturing costs of the excrement treatment material  1 . 
     In the case where the core portion  12  and the core portion  22  are made of materials that have different composition, it is possible to use a material having a relatively high water absorbing property as the first core portion material, and use a material having a relatively low water absorbing property as the second core portion material. Thus, the grain  10  and the grain  20  that have mutually different water absorption rates can easily be realized. 
     The grain  10  and the grain  20  are both provided with the coating portion (coating portions  14 ,  24 ). Thus, bonding of the coating portions between used grains  10 ,  20  is obtained, and therefore an agglomeration of the grains  10 ,  20  can be formed stably, compared to a case where only either one of the grain  10  or the grain  20  is provided with the coating portion. 
     The coating portion  14  and the coating portion  24  are made of materials that have the same composition. Thus, it is possible to use the same coating material as the coating material for forming the coating portion  14  (the first coating material) and the coating material for forming the coating portion  24  (the second coating material). This contributes to reduction in manufacturing costs of the excrement treatment material  1 . 
     The core portion  12  and the core portion  22  do not contain an adhesive material. Thus, it is possible to save the amount of the adhesive material used and thereby reduce manufacturing costs of the excrement treatment material  1 . 
     In the case where the core portion  12  and the coating portion  14  contain an organic substance as the main material, the grain  10  can be obtained that is suitable for being disposed of by incineration. Similarly, in the case where the core portion  22  and the coating portion  24  contain an organic substance as the main material, the grain  20  can be obtained that is suitable for being disposed of by incineration. When the grains  10 ,  20  are suitable for being disposed of by incineration in this way, used excrement treatment material  1  can be discarded as combustible trash, and therefore convenience for the users is improved. 
     The present invention is not limited to the above-described embodiment, and various modifications can be made. In the above-described embodiment, the first coating step and the second coating step may be performed simultaneously with the same apparatus. That is, the first and second coating steps may be performed as one step. In that step, after mixing the core portions  12  and the core portions  22 , the coating portions  14 ,  24  can be formed by attaching a common coating material (the first and second coating materials) to the surface of each of the core portions  12 ,  22  with the same coating apparatus or the like. Thus, the excrement treatment material  1  can be manufactured efficiently in which the grains  10  and the grains  20  are provided in a mixed manner. This also contributes to reduction in manufacturing costs of the excrement treatment material  1 . 
     In the above-described embodiment, an example is given in which the coating portion  24  is made of the material having the same composition as the coating portion  14 . However, the coating portion  24  may be made of a material having different composition from the coating portion  14 . In that case, it is possible to use a material having a relatively high water absorbing property as the first coating material, and use a material having a relatively low water absorbing property as the second coating material. 
     In the above-described embodiment, an example is given in which the grain  10  and the grain  20  are both provided with the coating portion. However, only either one of the grain  10  or the grain  20  may be provided with the coating portion. For example, the grain  20  may not be provided with the coating portion  24  while the grain  10  is provided with the coating portion  14 . In that case, the grain  20  has single-layer structure composed only of the core portion  22 . That is, the core portion  22  is uncovered in the grain  20 . Providing only a part of grains (the grain  10 ) with the coating portion makes it possible to save the coating material. Moreover, the bonding effect of the coating portion  14  provided in the grain  10  is also exerted on the grain  20  around the grain  10 . For this reason, even though the grain  20  is not provided with a coating portion, an agglomeration composed of used grains  10 ,  20  is formed. Accordingly, it is possible to obtain an agglomeration of the grains  10 ,  20  after use while saving the coating material. 
     Note that neither the grain  10  nor the grain  20  may be provided with a coating portion. That is, the grain  10  and the grain  20  both may have single-layer structure composed only of the core portion (core portions  12 ,  22 ). 
     In the above-described embodiment, an example is given in which the core portion  12  does not contain an adhesive material. However, the core portion  12  may contain an adhesive material. The same shall apply to the core portion  22 . 
     In the above-described embodiment, an example is given in which the particle diameter of the grain  20  is larger than the particle diameter of the grain  10 . However, the particle diameter of the grain  20  may be equal to or smaller than the particle diameter of the grain  10 . 
     LIST OF REFERENCE NUMERALS 
       1  Excrement Treatment Material 
       10  Grain (First Grain) 
       12  Core Portion (First Granule) 
       14  Coating Portion (First Coating Portion) 
       20  Grain (Second Grain) 
       22  Core Portion (Second Granule) 
       24  Coating Portion (Second Coating Portion) 
       90  Excrement Treatment Material 
       92  Grain 
       94  Toilet 
       96  Urine