Treatment agent for used absorbent article

Abstract

To provide a technique capable of efficiently dehydrating a water-absorbing resin of a used absorbent article.SOLUTION: A treatment agent for a used absorbent article is a treatment agent for a used absorbent article containing a water-absorbing resin, and contains a polyvalent metal salt, and a surface active agent composed of at least one of a nonionic surface active agent and an anionic surface active agent.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a technique for treating used absorbent articles containing a water-absorbent resin. [Background technology]

[0002] Absorbent articles such as disposable diapers may contain water-absorbent resins to enhance absorbency. Water-absorbent resins have the property of absorbing a large amount of water and swelling. For this reason, absorbent articles containing water-absorbent resins become heavy due to the water absorbed after use, which may increase the burden of disposal. Furthermore, used absorbent articles containing a large amount of water hinder incineration, which increases the environmental load.

[0003] Therefore, there are known techniques for dehydrating used absorbent articles containing water-absorbent resins. For example, Patent Document 1 discloses a technique for removing water from used disposable diapers using a treatment liquid containing divalent metal ions such as calcium chloride. Patent Document 2 discloses a technique for applying a physical force to used sanitary products in an aqueous solution containing polyvalent metal ions to dehydrate the highly water-absorbent polymer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-112725 [Patent Document 2] JP 2017-193819 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the dehydration treatments of used absorbent articles described in Patent Documents 1 and 2 require a long time until the moisture content of the used absorbent articles is sufficiently reduced, and therefore there is a demand for a technology for more efficiently dehydrating used absorbent articles.

[0006] The present invention relates to a technique capable of efficiently dehydrating a water-absorbent resin in a used absorbent article. [Means for solving the problem]

[0007] A treatment agent for used absorbent articles according to one embodiment of the present invention is a treatment agent for used absorbent articles containing a water-absorbent resin, A polyvalent metal salt; a surfactant comprising at least one of a nonionic surfactant and an anionic surfactant; Contains:

[0008] A method for treating used absorbent articles according to another aspect of the present invention is a method for treating used absorbent articles, which comprises dehydrating a water-absorbent resin contained in the used absorbent articles, the method comprising the steps of: The method includes a step of immersing the used absorbent article in a treatment liquid containing a polyvalent metal salt and a surfactant consisting of at least one of a nonionic surfactant and an anionic surfactant. Effect of the Invention

[0009] According to the present invention, it is possible to efficiently dehydrate the water-absorbent resin in a used absorbent article. [Brief description of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view of a used absorbent article according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] [Summary of the Invention] The present invention relates to a treating agent for used absorbent articles, which is capable of efficiently dehydrating a water-absorbent resin in used absorbent articles, and a method for treating used absorbent articles. In this specification, the treating agent for absorbent articles is also referred to as a "treating agent", and the method for treating used absorbent articles is also referred to as a "treating method". The water-absorbent resin used in absorbent articles has the property of being able to absorb and retain a large amount of water, but is difficult to release water. According to the technology of the present invention, the release of water from the water-absorbent resin in an absorbent state can be promoted, and the water-absorbent resin can be efficiently dehydrated. In addition, by dehydrating the absorbent resin using this technology, the weight of used absorbent articles can be reduced, and the burden of disposal can be reduced. In addition, by reducing the amount of moisture in used absorbent articles, incineration can be promoted, and the environmental burden can be reduced. Furthermore, by dehydrating the absorbent resin, it becomes easier to separate the absorbent resin from other components of used absorbent articles, and it is also possible to promote the recycling of each component of used absorbent articles.

[0012] In the present invention, the absorbent article means an article that has a water-absorbent resin and can absorb water. Examples of the absorbent article include disposable diapers, sanitary napkins, urine pads, panty liners, pet toilet sheets, drip sheets, moisture absorbents, deodorants, etc. The "drip sheet" means a water-absorbent sheet that absorbs excess water (body fluids, etc.) from food ingredients such as meat and fish. In the present invention, a used absorbent article means an absorbent article in a state in which it has absorbed moisture after use. Furthermore, in the present invention, the absorbent article is preferably an absorbent sanitary product that absorbs body fluids such as urine, menstrual blood, etc. Examples of absorbent sanitary products include disposable diapers, sanitary napkins, urine pads, panty liners, etc.

[0013] The absorbent article of the present invention preferably has, as a specific configuration, for example, an absorbent body containing a water-absorbent resin and a covering material that covers the absorbent body. Furthermore, it is more preferable that the covering material includes a leakproof sheet in order to suppress leakage of moisture absorbed in the absorbent body to the outside. Specific configuration examples of such an absorbent article will be described later. When dehydrating an absorbent resin from an absorbent article having a configuration in which the absorbent resin (absorbent body) is covered with a covering material, etc., the permeability of a treatment liquid into the absorbent article is important. According to the technology of the present invention, as described in detail below, the permeability of a treatment liquid into the absorbent article can be increased, thereby improving the dehydration efficiency.

[0014] Water-absorbent resins generally have a three-dimensional network structure in which the main chains having hydrophilic groups are crosslinked. Water-absorbent resins can retain moisture in the network formed by the main chains and crosslinked chains. Specifically, the water-absorbent resin includes at least one selected from, for example, a partially crosslinked polymer compound having a carboxyl group or a salt thereof, or a partially crosslinked polysaccharide. Examples of the partially crosslinked polymer compound having a carboxyl group or a salt thereof include, for example, a polyacrylate crosslinked product, a poly(vinyl alcohol / acrylate) copolymer (crosslinked product), a starch-acrylate graft copolymer (crosslinked product), and a polyvinyl alcohol-polymaleic anhydride graft copolymer (crosslinked product). Examples of the partially crosslinked polysaccharide include, for example, a carboxymethyl cellulose salt crosslinked product. In addition, examples of the "salt" constituting the water absorbent resin include alkali metal salts (sodium salts, potassium salts, lithium salts, etc.), alkaline earth metal salts (calcium salts, magnesium salts, barium salts, etc.), ammonium salts (quaternary ammonium salts, quaternary alkyl ammonium salts, etc.), etc.

[0015] [Treatment agent for used absorbent articles] The treatment agent according to one embodiment of the present invention contains a polyvalent metal salt and a surfactant consisting of at least one of a nonionic surfactant or an anionic surfactant. In the treatment agent according to this embodiment, the polyvalent metal salt has a dehydrating effect on the water-absorbent resin, and the nonionic surfactant or anionic surfactant is considered to increase the permeability of the polyvalent metal salt into the inside of the absorbent article. Therefore, the treatment agent can increase the dehydration efficiency of the water-absorbent resin.

[0016] The treatment agent according to the present embodiment is an agent for preparing a treatment liquid in which a used absorbent article is soaked and dehydrated. The treatment agent may be the treatment liquid itself, but from the viewpoint of facilitating distribution and storage, it is preferable that the treatment agent is an agent that can prepare a treatment liquid by mixing with water. In the latter case, the treatment agent may be in a solid or liquid form. When the treatment agent is in a solid form, it is preferable that the treatment agent is in a powder or granular form in order to increase the solubility or dispersibility in water.

[0017] (polyvalent metal salts) It is believed that the polyvalent metal salt according to this embodiment acts on the hydrophilic group of the water-absorbent resin, inhibiting the hydrogen bond between the hydrophilic group and water molecules, and releasing the water molecules. In addition, the polyvalent metal salt can form new crosslinks by bonding with multiple hydrophilic groups of the water-absorbent resin. This causes the three-dimensional network structure of the water-absorbent resin to shrink, and the water molecules held in the network are released.

[0018] In this embodiment, the polyvalent metal salt may be any salt having the above-mentioned action, but is preferably a divalent or trivalent metal salt. For example, the polyvalent metal salt in this embodiment is preferably at least one selected from an alkaline earth metal salt, a transition metal salt, and an aluminum salt. Examples of alkaline earth metal salts include salts of beryllium, magnesium, calcium, strontium, and barium.Specific examples of alkaline earth metal salts include calcium chloride, calcium nitrate, calcium hydroxide, calcium oxide, magnesium chloride, and magnesium nitrate. Examples of transition metal salts include iron, cobalt, nickel, copper, etc. Examples of transition metal salts include inorganic acid salts, organic acid salts, complexes, etc. of transition metals. Examples of inorganic acid salts include iron salts such as iron chloride, iron sulfate, iron phosphate, and iron nitrate, cobalt salts such as cobalt chloride, cobalt sulfate, cobalt phosphate, and cobalt nitrate, nickel salts such as nickel chloride and nickel sulfate, and copper salts such as copper chloride and copper sulfate. Examples of organic acid salts include iron lactate, cobalt acetate, cobalt stearate, nickel acetate, and copper acetate. Examples of aluminum salts include aluminum chloride and aluminum sulfate. Of these, the polyvalent metal salt of the present embodiment preferably contains calcium chloride from the standpoints of safety, cost, and the like.

[0019] (Surfactant) The treatment agent according to the present embodiment contains a surfactant consisting of at least one of a nonionic surfactant and an anionic surfactant. The surfactant in the present embodiment is considered to have the effect of increasing the affinity between the treatment liquid containing a polyvalent metal salt and the used absorbent article, thereby increasing the permeability of the treatment liquid into the used absorbent article.

[0020] In particular, the surfactant according to the present embodiment preferably contains at least one nonionic surfactant. It is believed that the nonionic surfactant can increase the permeability of the treatment liquid through a hydrophobic member, such as a leakproof sheet material, even when the used absorbent article contains the hydrophobic member.

[0021] Specific examples of the nonionic surfactant include polyoxyethylene sorbitan fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene alkyl ether, polyoxyethylene alkenyl ether, polyether modified silicone, alkyl glucoside, alkyl alkanolamide, alkyl glyceryl ether, higher fatty acid sucrose ester, polyglycerin fatty acid ester, polyoxyethylene hydrogenated castor oil, and alkyl saccharide. Among these, from the viewpoint of further increasing the permeability of the treatment liquid into used absorbent articles, it is preferable that the nonionic surfactant contains polyoxyethylene sorbitan fatty acid ester. The nonionic surfactant may be used alone or in combination of two or more kinds.

[0022] From the viewpoint of enhancing the permeability of the treatment liquid into used absorbent articles, the HLB (Hydrophilic-Lipophilic Balance) value of the nonionic surfactant is preferably 8.0 or more, more preferably 9.0 or more and 15.0 or less. It is considered that the nonionic surfactant having an HLB value in the above-mentioned suitable range can optimize the balance between the affinity for the aqueous treatment liquid and the affinity for used absorbent articles containing hydrophobic members, etc. The HLB value indicates the affinity of a surfactant for water and oil, and can be calculated by the Griffin method using the following formula. HLB = 20 × [(molecular weight of hydrophilic group contained in surfactant) / (molecular weight of surfactant)] When two or more types of nonionic surfactants are used, it is preferable to use two or more types of components having HLB values ​​within the above range.

[0023] In the present embodiment, the treatment agent may contain an anionic surfactant. The anionic surfactant is a surfactant having an anionic group, and includes those that exhibit anionicity by adjusting the pH. It is considered that the treatment agent contains an anionic surfactant, and thus the affinity of the treatment agent to the water absorbent resin can be increased even when the water absorbent resin contains a cation.

[0024] Examples of anionic surfactants include alkylbenzenesulfonates, alkyl or alkenyl ether sulfates, alkyl or alkenyl sulfates, olefinsulfonates, alkanesulfonates, sodium polyoxyethylene alkyl ether sulfates, saturated or unsaturated fatty acid salts, alkyl or alkenyl ether carboxylates, α-sulfofatty acid salts, N-acylamino acid salts, mono- or di-phosphate esters, and sulfosuccinate esters. The anionic surfactants may be used alone or in combination of two or more. The anionic surfactants may also be used in combination with the above-mentioned nonionic surfactants.

[0025] In the treatment agent of this embodiment, the content of the surfactant is preferably 0.01 parts by mass or more, more preferably 0.015 parts by mass or more, and preferably 0.72 parts by mass or less, more preferably 0.20 parts by mass or less, per 1 part by mass of polyvalent metal salt, in order to fully exert the effect of improving the permeability of used absorbent articles. In addition, when the surfactant contains multiple types of nonionic surfactants and / or anionic surfactants, the surfactant content is the total content of the multiple surfactants. In addition, when the treatment agent contains multiple types of polyvalent metal salts, the polyvalent metal salt content is the total content of the multiple polyvalent metal salts.

[0026] [How to dispose of used absorbent articles] A treatment method according to one embodiment of the present invention is a method for dehydrating a water-absorbent resin contained in a used absorbent article. The treatment method according to this embodiment includes at least an immersion step of immersing a used absorbent article in a treatment liquid containing a polyvalent metal salt and a surfactant consisting of at least one of a nonionic surfactant or an anionic surfactant. In the immersion step, it is considered that the at least one of the nonionic surfactant or the anionic surfactant improves the permeability of the treatment liquid into the used absorbent article, and the polyvalent metal salt promotes dehydration of the used absorbent article. In the immersion step, moisture released from the water-absorbent resin of the used absorbent article is transferred to the treatment liquid.

[0027] The treatment liquid according to the present embodiment may be prepared by mixing a polyvalent metal salt and at least one of a nonionic surfactant or an anionic surfactant in water. Alternatively, the treatment liquid may be prepared using the above-mentioned treatment agent, for example, the treatment agent itself may be used as the treatment liquid. Alternatively, the treatment liquid may be prepared by mixing the treatment agent with water. It is preferable that the treatment liquid is sufficiently mixed so that the above-mentioned contained components are dissolved or uniformly dispersed in water.

[0028] The immersion step according to the present embodiment is performed, for example, by storing the treatment liquid and the used absorbent article in a treatment tank having a sufficient volume. In the immersion step, it is preferable to stir the treatment liquid in which the used absorbent article is immersed, from the viewpoint of sufficiently reacting the treatment liquid with the used absorbent article. This can increase the permeability of the treatment liquid into the used absorbent article, and the water-absorbing resin can be efficiently dehydrated. The treatment liquid may be stirred using a stirrer or the like, or may be stirred by driving the treatment tank. In the immersion step according to the present embodiment, a washing machine may be used as an example. In this case, for example, the used absorbent article and the treatment agent are put into the washing tub of the washing machine, and the washing machine is started. As a result, water is injected into the washing tub and the washing tub rotates, and the immersion treatment with stirring is automatically performed. Furthermore, by using a washing machine, in addition to the immersion step, at least a part of the separation step, washing step, or water removal step described later can be performed in the same device.

[0029] In the immersion step according to the present embodiment, at least a part of the used absorbent article may be immersed in the treatment liquid. From this viewpoint, the amount of the treatment liquid added may be appropriately set according to the amount of the used absorbent article, the shape of the treatment tank, etc. For example, the amount of the treatment liquid added is preferably 2 parts by mass or more, more preferably 3 parts by mass or more, and is preferably 220 parts by mass or less, more preferably 150 parts by mass or less, per 1 part by mass of the used absorbent article.

[0030] The immersion time in the immersion step is not particularly limited as long as the water absorbent resin can be sufficiently dehydrated, but is preferably 3 minutes or more, more preferably 5 minutes or more, and preferably 30 minutes or less, more preferably 20 minutes or less. In the treatment method according to the present embodiment, the dehydration efficiency of the water absorbent resin can be increased, so that used absorbent articles can be treated in a short time.

[0031] From the viewpoint of reducing costs and increasing dehydration efficiency, the concentration of the polyvalent metal salt in the treatment liquid is preferably 400 ppm or more, more preferably 700 ppm or more, and preferably 3500 ppm or less, more preferably 3000 ppm or less. When the treatment liquid contains multiple types of polyvalent metal salts, the concentration of the polyvalent metal salt refers to the total concentration of the multiple polyvalent metal salts.

[0032] The concentration of the surfactant in the treatment liquid is preferably 30 ppm or more, more preferably 50 ppm or more, from the viewpoint of increasing the dehydration efficiency. Also, the concentration of the surfactant in the treatment liquid is preferably 2000 ppm or less, more preferably 700 ppm or less, from the viewpoint of reducing costs. In addition, when the surfactant contains multiple types of nonionic surfactants and / or anionic surfactants, the concentration of the surfactant is the total concentration of the multiple types of surfactants. In particular, by setting the concentration of the nonionic surfactant in the treatment liquid to 50 ppm or more, the dehydration efficiency can be improved more reliably.

[0033] [Variations] The treatment method according to this embodiment may include the following steps in addition to the immersion step. For example, the treatment method according to the present embodiment preferably includes a separation step of separating the used absorbent article from the treatment liquid after the immersion step. The separation step removes moisture released from the used absorbent article together with the treatment liquid. The specific aspect of the separation step is not particularly limited, and for example, the treatment liquid may be drained from the treatment tank used in the immersion step. A pump or a drain pipe connected to the treatment tank may be used for draining the water. Alternatively, the used absorbent article may be removed from the treatment tank containing the treatment liquid.

[0034] The treatment method according to the present embodiment may further include a washing step of washing the used absorbent article separated from the treatment liquid after the separation step. The used absorbent article can be washed, for example, by rinsing the used absorbent article with water. This makes it possible to remove excrement and the like adhering to the used absorbent article that could not be sufficiently removed in the soaking step.

[0035] Furthermore, the treatment method according to the present embodiment may include a moisture removal step of removing moisture remaining in the used absorbent articles after the separation step, preferably after the cleaning step, which can further reduce the weight of the used absorbent articles and the burden of disposal and the environmental load during incineration. In the moisture removal step, moisture may be removed by applying a physical force to the used absorbent article, or the used absorbent article may be dried. Specific treatments for applying a physical force are not particularly limited, and examples thereof include dehydration treatments using a centrifugal dehydrator, a press dehydrator, etc., and squeezing treatments using a squeezing machine, etc. Specific treatments for drying the used absorbent article include heating and air drying of the used absorbent article, etc.

[0036] [Example of composition of used absorbent products] A used absorbent article (hereinafter referred to as "absorbent article") 1 used in one embodiment of the present invention has an absorbent body 4 containing a water-absorbent resin 41, and a covering material 5 that covers the absorbent body 4, as illustrated in the cross-sectional view of Figure 1. The absorbent body 4 has a function of absorbing and retaining moisture. In addition to the water-absorbent resin 41, the absorbent body 4 may contain a hydrophilic material such as pulp fiber.

[0037] In the example shown in Fig. 1, the covering material 5 has a first sheet 2 and a second sheet 3 that face each other with an absorbent body 4 sandwiched between them. The first sheet 2 and the second sheet 3 are preferably joined by, for example, an adhesive and / or heat sealing. When the absorbent article 1 is configured as a used sanitary product, the first sheet 2 may be configured as, for example, a top sheet that is liquid permeable and is placed on the skin side of the wearer. This allows the first sheet 2 to pass through bodily fluids excreted from the wearer, allowing the absorbent body 4 to absorb the bodily fluids.

[0038] In this embodiment, the second sheet 3 is configured as a leakproof sheet having leakproof properties. The leakproof sheet is a sheet having a function of preventing the moisture held by the absorbent body 4 from leaking to the outside, and has, for example, poor liquid permeability and / or water repellency. Examples of such leakproof sheets include a film, a laminated sheet of a film and a nonwoven fabric, and a leakproof nonwoven fabric. The film may be, for example, a moisture-permeable sheet having fine air holes. When the absorbent article 1 is configured as a used sanitary product, the second sheet 3 may be configured as, for example, a back sheet arranged on the non-skin side of the wearer.

[0039] In this embodiment, the second sheet 3 is preferably configured as a leakproof nonwoven fabric. By configuring the second sheet 3 as a nonwoven fabric, the treatment liquid can easily permeate through the gaps between the fibers to the absorbent body 4 side, and the dehydration efficiency can be further improved. The nonwoven fabric used as the leakproof sheet includes a nonwoven fabric layer formed by a known manufacturing method such as a melt-blowing method, a spunbonding method, an air-through method, an air-laid method, a spunlace method, a needle punching method, an electrospinning method, a chemical bonding method, and a thermal bonding method. This nonwoven fabric may be configured as one layer or may have multiple layers. An example of a nonwoven fabric having multiple layers is a composite nonwoven fabric including a spunbonding layer and a melt-blown layer.

[0040] The leakproof nonwoven fabric is preferably a nonwoven fabric containing fibers containing a polyolefin resin and triglyceride (see, for example, Japanese Patent No. 7058378). As the polyolefin resin, for example, a homopolymer or copolymer of a lower olefin such as ethylene or propylene can be used. Specific examples include polyethylene, polypropylene, and ethylene-α-olefin copolymers. Among the polyolefin resins, polyolefins containing polypropylene and propylene as copolymerization components are preferably used from the viewpoint of high fiber forming ability and high barrier properties against liquids of the resulting nonwoven fabric.

[0041] In the nonwoven fabric, triglyceride is used to reduce the surface tension of the fibers constituting the nonwoven fabric and to enhance the barrier properties of the nonwoven fabric against liquids. The triglyceride may be present in a state of being attached to the surface of the fibers, or may be present by being kneaded into the resin constituting the fibers. As the triglyceride, it is preferable to use the following (a) or (b). (a) A triglyceride comprising a mixture of a triglyceride containing at least one group derived from a fatty acid having 16 carbon atoms in one molecule and a triglyceride containing at least one group derived from a fatty acid having 18 carbon atoms in one molecule. (b) A triglyceride containing at least one group derived from a fatty acid having 16 carbon atoms and one group derived from a fatty acid having 18 carbon atoms in one molecule. As such triglycerides, triglycerides derived from saturated fatty acids, triglycerides derived from unsaturated fatty acids, and triglycerides derived from saturated and unsaturated fatty acids can be used. In any case, the number of carbon atoms of the fatty acid can be, for example, 12 or more and 24 or less. From the viewpoint of further improving the barrier property of the nonwoven fabric against liquids, the number of carbon atoms of the fatty acid is preferably 14 or more and 22 or less, more preferably 16 or more and 20 or less. Only one type of triglyceride may be used, or a mixture of multiple types of triglycerides may be used. An example of a triglyceride that is preferably used in the nonwoven fabric is extremely hardened palm oil.

[0042] [Other embodiments] Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0043] The treatment agent and / or treatment liquid according to the present invention may contain, in addition to the above-mentioned components, any optional components within the range in which the effects of the present invention are exhibited.

[0044] In the above-described embodiment, an example was described in which the covering material 5 of the used absorbent article 1 has a liquid-permeable first sheet 2 in addition to the second sheet (leakproof sheet) 3, but the configuration of the used absorbent article is not limited to this. EXAMPLES

[0045] Examples and comparative examples of the treatment method of the present invention will be described. As examples and comparative examples of the present invention, diaper samples were prepared to simulate actual used absorbent articles. The diaper samples of each example and comparative example were immersed in a predetermined treatment liquid to perform a dehydration test, and the water retention capacity of each example and comparative example sample after dehydration treatment was calculated. A treatment liquid containing calcium chloride, which is a polyvalent metal salt, and a nonionic surfactant or an anionic surfactant was used in Examples 1 to 10. A treatment liquid containing neither a nonionic surfactant nor an anionic surfactant was used in Comparative Examples 1 to 3.

[0046] [Preparation of Samples for Example 1 and Comparative Example 1] As a sample of Example 1 and Comparative Example 1, an adult diaper (Relief Powerful Incontinence Pad Wide Night Use No. 5, manufactured by Kao Corporation) was prepared. This diaper had an absorbent body containing a water-absorbing resin, a liquid-permeable sheet (top sheet) arranged on the absorbent body, and a leakproof sheet (back sheet) arranged opposite the liquid-permeable sheet with the absorbent body sandwiched therebetween. The water-absorbing resin used was a polyacrylic acid sodium salt polymer (IM997, manufactured by SDP Global Co., Ltd.). The leakproof sheet was a moisture-permeable film having fine air holes.

[0047] [Preparation of Samples for Examples 2 to 12 and Comparative Examples 2 to 3] As the samples of Examples 2 to 12 and Comparative Examples 2 to 3, samples were prepared in which the leakproof sheet was replaced with a nonwoven fabric sheet in the same commercially available adult diaper as in Example 1. The nonwoven fabric sheet was a composite nonwoven fabric sheet consisting of a spunbond layer and a meltblown layer. The basis weight of the nonwoven fabric sheet was 21.5 g / m 2 The weight of the meltblown layer is 6.5 g / m 2 The fiber diameter of the spunbond layer was 16.5 μm. The fiber diameter of the meltblown layer was 2.1 μm. The fiber diameter of the meltblown layer was 2.1 μm. The spunbond layer was composed of fibers containing homopolypropylene and a lubricant. The fiber diameter of the meltblown layer was 2.1 μm. The meltblown layer was composed of fibers containing 67% homopolypropylene, 23% random propylene copolymer, and 10% highly hydrogenated palm oil.

[0048] [Preparation of pseudo used diapers] First, the mass of each diaper sample was measured before the test. Then, 500 g of physiological saline (manufactured by Otsuka Pharmaceutical Co., Ltd.) was poured into each diaper sample and allowed to stand for 10 minutes to prepare a simulated used diaper.

[0049] [Preparation of processing solution] 30 L of tap water was poured into a twin-tub washing machine (NA-W50B1, manufactured by Panasonic Corporation). 84 g (0.28% by mass) of calcium chloride and a surfactant shown in Tables 1 to 3 were dissolved in the tap water as a treatment agent to prepare treatment liquids for each Example and Comparative Example. In Examples 1 to 8 and Comparative Example 3, the amount of surfactant added was 15 g, and the concentration of the surfactant in the treatment liquid was 0.05% by mass (500 ppm). In Example 9, the amount of surfactant added was 0.9 g, and the concentration of the surfactant in the treatment liquid was 0.003% by mass (30 ppm). In Example 10, the amount of surfactant added was 1.5 g, and the concentration of the surfactant in the treatment liquid was 0.005% by mass (50 ppm). In Example 11, the amount of surfactant added was 3 g, and the concentration of the surfactant in the treatment liquid was 0.01% by mass (100 ppm). In Example 12, the amount of surfactant added was 60 g, and the concentration of the surfactant in the treatment liquid was 0.2 mass % (2000 ppm). Note that in Comparative Examples 1 and 2, no surfactant was added.

[0050] [Table 1]

[0051] [Table 2]

[0052] [Table 3]

[0053] Among the surfactants shown in Tables 1 to 3, Rheodol TW-L106 and Rheodol TW-L120 were nonionic surfactants and were manufactured by Kao Corporation. Emulgen 103, Emulgen 106, and Emulgen 109P were nonionic surfactants and were manufactured by Kao Corporation. KF-640 was a nonionic surfactant and was manufactured by Shin-Etsu Chemical Co., Ltd. Emal 270J was an anionic surfactant and was manufactured by Kao Corporation. Sanizol B-50 was a cationic surfactant and was manufactured by Kao Corporation. The HLB values ​​of each nonionic surfactant were as shown in Tables 1 to 3.

[0054] [Dehydration test] The following spin-drying test was carried out using the diaper samples and treatment liquid of each Example and Comparative Example. First, four pseudo-used diapers were placed in a washing tub containing the treatment liquid and agitated for 5 minutes on a standard cycle. After the immersion treatment, the treatment liquid was drained from the washing tub, and then 30 L of tap water was poured into the washing tub and agitated for 3 minutes on a standard cycle, and the diapers were rinsed to wash away excess components. After the washing treatment, the diapers were transferred to a spin-drying tub and centrifugally dehydrated for 5 minutes. The mass of each diaper after the centrifugation was measured, and the water retention capacity of each diaper was calculated using the following formula. Water retention capacity [g] = weight of diaper after dehydration [g] - weight of diaper before use [g] The average value of the water retention capacity of the four diapers in each Example and Comparative Example was calculated, and this value was regarded as the water retention capacity of each Example and Comparative Example. The results are shown in Tables 1 to 3.

[0055] [Results of Example 1 and Comparative Example 1] The results of Example 1 and Comparative Example 1 using diaper samples having a moisture-permeable film will be described. As shown in Table 1, the sample of Example 1 using a treatment agent containing a polyoxyethylene sorbitan fatty acid ester as a nonionic surfactant had a significantly smaller amount of water retention after dehydration than the sample of Comparative Example 1 using a treatment agent containing no surfactant. This result shows that the dehydration efficiency is improved by using a treatment agent containing a nonionic surfactant in addition to a polyvalent metal salt.

[0056] [Results of Examples 2 to 8 and Comparative Examples 2 to 3] The results of Examples 2 to 8 and Comparative Examples 2 to 3 using diaper samples having a leakproof nonwoven fabric sheet will be described. As shown in Table 2, the samples of Examples 2 to 8 using a nonionic surfactant or anionic surfactant had a smaller amount of water retention after dehydration than the samples of Comparative Example 2 not using a surfactant and Comparative Example 3 using a cationic surfactant. This shows that the dehydration efficiency is improved by using a treatment agent containing a polyvalent metal salt and a nonionic surfactant or an anionic surfactant. Furthermore, the average water retention of the samples of Examples 2 to 7 using a nonionic surfactant was 92.7 g, while the water retention of the sample of Example 8 using an anionic surfactant was 96 g. This result shows that the dehydration efficiency is more easily improved by using a treatment agent containing a polyvalent metal salt and a nonionic surfactant.

[0057] Next, the water retention of the samples of Examples 2 to 4 using the same kind of surfactant is compared. The samples of Examples 3 and 4 using polyoxyethylene alkyl ethers having HLB values ​​of 10.5 and 13.6 had smaller water retention after dehydration than the sample of Example 2 using polyoxyethylene alkyl ether having HLB value of 8.1. From this result, it was found that the dehydration efficiency is further improved by using a nonionic surfactant with an HLB value of 9.0 or more.

[0058] In addition, the water retention of the samples of Examples 6 and 7 using the same kind of surfactant is compared. The sample of Example 6 using polyoxyethylene sorbitan fatty acid ester having an HLB value of 13.3 had a smaller water retention after dehydration than the sample of Example 7 using polyoxyethylene sorbitan fatty acid ester having an HLB value of 16.7. This shows that the dehydration efficiency is further improved by using a nonionic surfactant with an HLB value of 15.0 or less.

[0059] Furthermore, the sample of Example 6 using polyoxyethylene sorbitan fatty acid ester had the smallest water retention among the samples of Examples 2 to 7 using the same concentration of nonionic surfactant. This shows that the dehydration efficiency is further improved by using polyoxyethylene sorbitan fatty acid ester as a nonionic surfactant.

[0060] [Results of Examples 6, 9 to 12] The results of Examples 6, 9 to 12, in which the concentration of the surfactant in the treatment liquid is different, will be described. From the results of Examples 6, 9 to 12, no clear tendency was observed that the dehydration efficiency improved depending on the surfactant concentration, but a tendency was observed in Example 10, in which the concentration was 50 ppm, and Example 11, in which the concentration was 100 ppm, in which the dehydration efficiency slightly increased. From these results, it was found that by setting the concentration to preferably 30 ppm or more, more preferably 50 ppm or more, and preferably 2000 ppm or less, more preferably 700 ppm or less, sufficient dehydration efficiency can be obtained while suppressing the amount of surfactant used. [Explanation of symbols]

[0061] 1. Used absorbent articles 2. Sheet 1 3...Leak-proof sheet (second sheet) 4…Absorbent 41…Water absorbent resin 5…Coating material

Claims

1. A treatment agent for used absorbent articles containing a water-absorbent resin, a polyvalent metal salt; a surfactant comprising at least one of a nonionic surfactant and an anionic surfactant; A treatment agent for used absorbent articles containing the above.

2. The surfactant includes a nonionic surfactant. The treatment agent for used absorbent articles according to claim 1.

3. The HLB value of the nonionic surfactant is 8.0 or more. The treatment agent for used absorbent articles according to claim 2.

4. The HLB value of the nonionic surfactant is 9.0 or more and 15.0 or less. The treatment agent for used absorbent articles according to claim 3.

5. At least one of the nonionic surfactants is a polyoxyethylene sorbitan fatty acid ester. The treatment agent for used absorbent articles according to claim 2.

6. The content of the surfactant is 0.01 parts by mass or more per 1 part by mass of the polyvalent metal salt. The treating agent for used absorbent articles according to claim 1 or 2.

7. A method for treating used absorbent articles, which dehydrates a water-absorbing resin contained in used absorbent articles, comprising: The method includes a step of immersing the used absorbent article in a treatment liquid containing a polyvalent metal salt and a surfactant consisting of at least one of a nonionic surfactant and an anionic surfactant. A method for disposing of used absorbent articles.

8. The surfactant includes a nonionic surfactant. The method for treating used absorbent articles according to claim 7.

9. The concentration of the surfactant in the treatment liquid is 30 ppm or more. The method for treating used absorbent articles according to claim 7 or 8.

10. The used absorbent article comprises: an absorbent body containing a water-absorbent resin; a covering material that covers the absorbent body, The covering material includes a leakproof sheet made of nonwoven fabric. The method for treating used absorbent articles according to claim 7 or 8.

Images