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    • 专利摘要:
    Water-absorbing resin particles comprising a cross-linked polymer comprising a monomer unit derived from a water-soluble ethylene unsaturated monomer are disclosed, at which an artificial menstrual blood swelling rate as measured in a swelling test of artificial menstrual blood conducted in the order of i), ii), and iii) is 70% or more. i) place 1.0 g of water-absorbing resin particles in a measuring cylinder with an internal diameter of 27 mm. ii) inject 10 ml of artificial menstrual blood into the cylinder at once to swell the water-absorbing resin particles. iii) measure a volume (A) of the swollen particles of water-absorbing resin after 60 seconds from the injection and calculate a rate of increase in volume of artificial menstrual blood according to Equation (I) below. Increase rate of artificial menstrual blood volume (%) = (AB) / Bx100 ... (I), A ... Volume (ml) of swollen water-absorbing resin particles, B ... Volume (ml) of injected artificial menstrual blood.
    公开号:BR112019020505A2
    申请号:R112019020505-5
    申请日:2018-03-28
    公开日:2020-06-23
    发明作者:Yabuguchi Hiroki；Hiroki Yabuguchi；Miyashita Hiromi；Hiromi Miyashita；Yokoyama Hideki；Hideki Yokoyama
    申请人:Sumitomo Seika Chemicals Co., Ltd.；
    IPC主号:
    专利说明:

    [0001] [0001] The present invention relates to water-absorbing resin particles. Knowledge Technique
    [0002] [0002] In recent years, a water-absorbent resin has been widely used for several fields, including hygienic materials such as paper diapers and sanitary napkins, agricultural and horticultural materials such as water retention materials and soil conditioners, industrial materials such as water blocking agents and dew condensation prevention agents, and the like. Among these fields, water-absorbent resin is most often used for hygienic materials such as paper diapers and sanitary napkins.
    [0003] [0003] As a water-absorbent resin, for example, a hydrolyzate of a starch graft copolymer - acrylonitrile, a neutralized product of a starch graft copolymer - acrylic acid, a saponified product of a vinyl acetate copolymer - acrylic acid ester, and a partially neutralized product of a polyacrylic acid, a hydrolyzate of an acrylonitrile copolymer, acrylamide copolymer, or crosslinked products thereof, a crosslinked product of a cationic monomer, or the like is known.
    [0004] [0004] Depending on the applications, several liquid-absorbing characteristics are required for the water-absorbent resin. For example, examples of the characteristics required in the case of application in hygienic material include (1) a high water absorption capacity, (2) a high water retention capacity (moisture holding performance in the water absorbent resin even after application). dehydration under a certain condition after water absorption), (3) a high water absorption rate, (4) a high resistance to gel after water absorption, and (5) a reduced amount of the absorbed liquid to return to the outside .
    [0005] [0005] Water-absorbent resin particles used in the field of hygienic materials are commonly appropriately cross-linked. For example, with regard to water-absorbing resins that are used in articles primarily intended for the absorption of human urine, such as paper diapers and incontinence pads, it is possible to improve the liquid absorption characteristics such as the absorption capacity of water and a gel resistance after water absorption to a certain extent controlling a degree of crosslinking.
    [0006] [0006] For the purpose of improving the liquid absorption characteristics of a water-absorbent resin to be applied to blood in particular, several techniques have been proposed. For example, in Patent Literature 1, a technique is disclosed in which a surface of a water-absorbent resin is treated with an aliphatic hydrocarbon or a specific hydrocarbon compound. In Patent Literature 2, a technique is disclosed in which a specific water-absorbent resin is coated with alkylene carbonate, and then heated to 150 ° C to 300 ° C. In addition, in Patent Literature 3, a technique is disclosed in which a water-absorbent resin having a large specific surface area and a high swelling power is used. Patent Literature Citation List
    [0007] [0007] [Patent Literature 1] JP S55-50355 A [Patent Literature 2] JP H05-508425 A [Patent Literature 3] WO 2002/085959 Summary of the Invention Technical Problem
    [0008] [0008] However, even a water-absorbent resin with a controlled degree of crosslinking has a problem that its liquid absorption characteristics such as a water absorption capacity and a water absorption rate are significantly decreased in one case. which targets blood significantly. Blood is a viscous liquid including plasma that contains protein and solid components such as erythrocytes, leukocytes, and platelets. The water-absorbent resin can absorb an aqueous solution and the like in nature, but it cannot absorb solid components. Therefore, it is considered that in a case where the blood is intended to be absorbed into water-absorbing resin particles, the solid components in the liquid adhere to the surfaces of the water-absorbing resin particles to coat the particle surfaces at a stage of early absorption, and thus further posterior absorption is stopped.
    [0009] [0009] Additionally, plasma which is a liquid component in the blood includes polymers such as a protein,
    [00010] [00010] In a case where in order to avoid gel blocking, for example, a surface of the water-absorbing resin particle is coated with materials including, for example, a hydrophobic material such as an aliphatic hydrocarbon, problems such as extremely low water absorption rate of the water absorbent resin particle itself, which thus causes rapid absorption by absorbent materials not being reached, occurs. In this sense, it cannot be said that the water-absorbent resin particles treated according to the related technique are not necessarily excellent in order to make the blood be absorbed inside the water-absorbent resin particles, in which there is an additional space for improvement.
    [00011] [00011] Therefore, an object of the present invention is to provide water-absorbing resin particles having excellent liquid-absorbing characteristics with respect to a viscous liquid containing a solid component such as blood, and an absorbent article using the same. Solution to the Problem
    [00012] [00012] The present inventors have recently discovered that water-absorbing resin particles having excellent liquid-absorbing characteristics with respect to a viscous liquid containing solid component can be obtained by increasing the volume after swelling when the water-absorbing resin particles absorb the liquid.
    [00013] [00013] That is, the present invention provides water-absorbent resin particles comprising a cross-linked polymer comprising a monomer unit derived from a water-soluble ethylene unsaturated monomer, at which an artificial menstrual blood volume increase rate 70% or more as measured in an artificial menstrual blood swelling test conducted in the following order of i), ii), and iii). i) Place 1.0 g of water-absorbing resin particles in a measuring cylinder with an internal diameter of 27 mm. ii) Inject 10 ml of artificial menstrual blood into the cylinder at once to swell the water-absorbing resin particles. iii) Measure a volume (A) of the swollen water-absorbing resin particles after a 60-second period from the injection and calculate an artificial menstrual blood swelling rate according to Equation (I) below. Increase rate of artificial menstrual blood volume (%) = (A-B) / Bx100 ... (I) A ... Volume (ml) of swollen water-absorbing resin particles
    [00014] [00014] Water-absorbing resin particles can exhibit excellent liquid-absorbing characteristics over a viscous liquid that contains a solid component such as blood.
    [00015] [00015] It is preferable that water-absorbent resin particles have a particle ratio having a particle diameter of more than 250 µm and 850 µm or less than 70% by weight or more and a particle ratio having a diameter of particle of 250 µm or less than 20% by mass or less, with respect to the total amount of water-absorbing resin particles.
    [00016] [00016] It is preferable that water-absorbent resin particles have an artificial menstrual blood absorption rate of 10 seconds or less.
    [00017] [00017] It is preferable that the water-absorbent resin particles have a physiological saline water retention capacity of 10 to 25 g / g.
    [00018] [00018] The present invention also provides an absorbent article comprising water-absorbent resin particles. The absorbent article has an excellent liquid-absorbing property for a viscous liquid that contains a solid component such as blood. Advantageous Effects of the Invention
    [00019] [00019] In accordance with the present invention, water-absorbing resin particles having excellent liquid-absorbing characteristics are provided for a viscous liquid containing a solid component such as blood, and an absorbent article using them. Brief Description of Drawings
    [00020] [00020] Fig. 1 is a photograph illustrating the results of artificial menstrual blood swelling tests in the Examples. Description of Achievements
    [00021] [00021] Hereinafter, suitable embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments. All configurations described in this specification can optionally be combined while not falling outside the scope of the present invention. For example, numerical value ranges for various characteristics can be defined using the upper limit values and the lower limit values of the numerical ranges described in this specification, or the numerical values optionally selected from the numerical values described in the Examples such as upper limit values and lower limit values.
    [00022] [00022] The water-absorbing resin particles according to the present embodiment comprise a cross-linked polymer comprising a monomer unit derived from a water-soluble ethylene unsaturated monomer. The water-absorbent resin particles according to the present embodiment have an artificial menstrual blood swelling rate of 70% or more.
    [00023] [00023] The rate of increase in artificial menstrual blood volume of water-absorbing resin particles is measured by an artificial menstrual blood swelling test conducted in the following order of i), ii), and iii). i) Place 1.0 g of water-absorbing resin particles in a measuring cylinder with an internal diameter of 27 mm. ii) Inject 10 ml of artificial menstrual blood into the cylinder at once to swell the water-absorbing resin particles. iii) Measure a volume (A) of the swollen water-absorbing resin particles after a 60-second period from the injection and calculate an artificial menstrual blood swelling rate according to Equation (I) below. Rate of increase in artificial menstrual blood volume (%) = (AB) / Bx100 ... (I) A ... Volume (ml) of swollen water-absorbed resin particles B ... Volume (ml) of blood injected artificial menstrual
    [00024] [00024] More specifically, it can be measured by the method described in the Examples which will be described below.
    [00025] [00025] An artificial menstrual blood swelling rate (60 second value) of the water-absorbent resin particles according to the present embodiment is, for example, preferably 75% or more, more preferably 80% or more, even more preferably 85% or more, and even more preferably 90% or more. In addition, the rate of increase in artificial menstrual blood volume of water-absorbing resin particles can be 95% or more, 100% or more, 110% or more, or 120% or more. In addition, the rate of increase in artificial menstrual blood volume of water-absorbing resin particles can be, for example, 200% or less, and can be 150% or less.
    [00026] [00026] An artificial menstrual blood volume increase rate (value of 300 seconds) after a period of 300 seconds from the injection of the water-absorbing resin particles according to the present embodiment can be, for example, 90% or more, 100% or more, 110% or more, 120% or more, or 130% or more, and can be 220% or less or 165% or less.
    [00027] [00027] It is considered that water-absorbing resin particles according to the present embodiment can reduce a gel blocking effect as the volumes and surface areas of the particles increase rapidly to protect voids that make it possible for a liquid from high viscosity such as blood is diffused between water-absorbing resin particles after being placed in contact with the liquid increasing the rate of artificial menstrual blood swelling. It is also considered that the particles become larger before the particle surfaces are coated with solid and similar components in the liquid to be absorbed due to the high rate of swelling of artificial menstrual blood, and appropriately, it becomes possible that the liquid is additionally absorbed into the particles while not inhibiting absorption. Therefore, the water-absorbing resin particles according to the present embodiment can exhibit high liquid absorption characteristics even with the liquid absorption after the second test.
    [00028] [00028] It is preferable that the water-absorbent resin particles according to the present embodiment have a particle ratio having a particle diameter of more than 250 µm and 850 µm or less than 70% by weight or more and a ratio of particles having a particle diameter of 250 µm or less than 20% by weight or less, with respect to the total amount of water-absorbing resin particles. In a case where the water-absorbing resin particles have the same shapes and sizes, since the particle diameters are smaller, the specific surface areas become larger, and in this sense, a technique for decreasing a particle diameter in a way increasing an absorption rate is known. On the other hand, water-absorbent resin particles according to the present embodiment having suitably large particle diameters are preferable since their liquid-absorbing characteristics with respect to a viscous liquid containing a solid component such as blood are further enhanced . In addition, in a case where the particle size distribution is within the range, the handling capacity is improved, which is preferable.
    [00029] [00029] The particle size distribution of water-absorbing resin particles can be measured using screens that have different mesh sizes. In the water-absorbent resin particles according to the present embodiment, a ratio of the particles having a particle diameter of more than 250 µm and 850 µm or less can be 75% or more, or it can be 80% by weight or more, 85% by weight or more, or 90% by weight or more, with respect to the total amount of water-absorbing resin particles. In the water-absorbent resin particles according to the present embodiment, a particle ratio having a particle diameter of 250 µm or less can be 18% by weight or less, 15% by weight or less, or 10% or less , with respect to the total amount of water-absorbing resin particles.
    [00030] [00030] The water-absorbing resin particles according to the present embodiment comprise a cross-linked polymer obtained by polymerizing monomers comprising water-soluble ethylene unsaturated monomers.
    [00031] [00031] Examples of a method for the polymerization of monomers include a reverse phase suspension polymerization method, an aqueous solution polymerization method, a mass polymerization method, and a precipitation polymerization method. Among these, from the point of view of making it easy to guarantee good liquid absorption characteristics of the water-absorbing resin particles obtained and control of the polymerization reaction, the reverse phase suspension polymerization method or the solution polymerization method aqueous is preferable.
    [00032] [00032] In order to increase the specific surface area of water-absorbing resin particles, for example, a method in which an anionic surfactant or a nonionic surfactant with a hydrophilic balance -
    [00033] [00033] Here below, a method of polymerization of water-soluble ethylene unsaturated monomers will be described by way of an example of the reverse phase suspension polymerization method.
    [00034] [00034] The water-soluble ethylene unsaturated monomer used in the production of the water-absorbing resin particles according to the present embodiment include (meth) acrylic acid ("acryl" and "methacryl" are collectively hereinafter referred to hereinafter as "( met) acryl ”, and similarly,“ acrylate ”and“ methacrylate ”are denoted as“ (met) acrylate ”) and salts thereof; 2- (meth) acrylamide-2-methylpropanesulfonic acid and salts thereof, (meth) acrylamide, N, N-dimethyl (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, N-methylol (meth) acrylamide, polyethylene glycol mono (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-diethylaminopropyl (meth) acrylate, and diethylaminopropyl (meth) acrylamide. In a case where the water-soluble ethylene unsaturated monomer contains an amino group, the amino group can be quaternized. A functional group such as a carboxyl group and an amino group, which is contained in the monomer, can function as a cross-linkable functional group in a step after cross-linking which will be described later. These water-soluble ethylene unsaturated monomers can be used alone or in a combination of two or more of the same types.
    [00035] [00035] Among these, at least one compound selected from the group consisting of acrylic acid and a salt thereof, methacrylic acid and a salt thereof, acrylamide, methacrylamide, and N, N-dimethyl acrylamide is preferably included in the monomer unsaturated with water-soluble ethylene, and at least one compound selected from the group consisting of acrylic acid and a salt thereof, methacrylic acid and a salt thereof, acrylamide, is most preferably included, from the point of view of that they are easily industrially available. At least one compound selected from the group consisting of acrylic acid and a salt thereof, and methacrylic acid and a salt thereof is even more preferably included in the water-soluble ethylene unsaturated monomer, from the point of view of enhancing additionally the water absorption characteristics.
    [00036] [00036] Like the monomer, some of the water-soluble monomers other than the water-soluble ethylene unsaturated monomers mentioned above can also be used to a degree that the display of the effect of the present invention is not inhibited. Such a monomer can be used, for example, in mixing an aqueous solution including water-soluble ethylene unsaturated monomers. An amount of the water-soluble ethylene unsaturated monomers to be used is preferably 70 to 100 mol% with respect to the total amount of the monomers. In particular, acrylic acid and a salt thereof are more preferably in the amount of 70% to 100 mol% with respect to the total amount of the monomers.
    [00037] [00037] Usually, water-soluble ethylene unsaturated monomers are used appropriately in the form of an aqueous solution. A concentration of the water-soluble ethylene unsaturated monomers in an aqueous solution of the water-soluble ethylene unsaturated monomers (hereinafter referred to as an aqueous monomer solution) can be commonly 20% by weight or more and no more than one saturated concentration, and is preferably 25% to 70% by weight, and more preferably 30% to 55% by weight. Examples of water to be used include tap water, distilled water, and ion exchange water.
    [00038] [00038] In a case where the water-soluble ethylene unsaturated monomer includes an acidic group, the aqueous monomer solution can be used after the acidic group is neutralized with an alkaline neutralizing agent. From the point of view of increasing the osmotic pressure of the water-absorbing resin particles and further improving the liquid absorption characteristics such as the water absorption rate, the degree of neutralization in the water-soluble unsaturated monomers with a alkaline neutralizing agent is 10% to 100 mol%,
    [00039] [00039] In the reverse phase suspension polymerization method, an aqueous monomer solution is dispersed in a hydrocarbon dispersion medium in the presence of a surfactant, and the polymerization of the water-soluble unsaturated monomers is carried out using a water initiator. polymerization of water-soluble radical or the like. With polymerization, an internal crosslinking agent can be used.
    [00040] [00040] Examples of the surfactant include nonionic surfactants and anionic surfactants. Examples of non-ionic surfactants include sorbitan fatty acid esters, (poly) glycerin fatty acid esters
    [00041] [00041] From the point of view that the effect with respect to the quantity of the surfactant to be used is sufficiently obtained and from the economic point of view, the quantity of the surfactant to be used is preferably 0.1 to 5 parts by weight, more preferably 0.2 to 3 parts by weight, and even more preferably 0.5 to 2 parts by weight, with respect to 100 parts by weight of the aqueous solution of the water-soluble ethylene unsaturated monomers.
    [00042] [00042] Examples of the water-soluble radical polymerization initiator include persulfates such as potassium persulfate, ammonium persulfate, and sodium persulfate; peroxides such as methyl ethyl peroxide ketone, methyl isobutyl peroxide ketone, di-t-butyl peroxide, t-butyl cumyl peroxide, t-butyl peroxyacetate, t-butyl peroxyisobutyrate, t-butyl peroxypivalate, and hydrogen peroxide; and azo compounds such as 2,2'-azobis (2-methylpropionamidine) dihydrochloride, 2,2'-azobis [2- (N-phenylamidino) propane] dihydrochloride, 2,2'-azobis [2- ( N-allylamidino) propane] dihydrochloride, 2,2'-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} dihydrochloride, 2,2'-azobis {2 - methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2,2'-azobis [2-methyl-N- (2-hydroxyethyl) -propionamide], and 4,4'- azobis (4-cyanovaleric acid). Each of these radical polymerization initiators can be used alone or in combination of two or more types thereof. In addition, the water solubility of the water-soluble radical polymerization initiator in this specification refers to the display of a solubility of 5% by mass or more in water at 25ºC.
    [00043] [00043] The amount of the water-soluble radical polymerization initiator to be used can be from 0.005 to 1 mol with respect to 100 mol of the water-soluble ethylene unsaturated monomers. In a case where the amount of the radical polymerization initiator to be used is 0.005 mol or more, the polymerization reaction does not require a long period of time, which is thus efficient. In a case where the amount of the radical polymerization initiator to be used is 1 mol or less, there is a tendency that an abrupt polymerization reaction does not occur.
    [00044] [00044] The water-soluble radical polymerization initiator can also be used as a redox polymerization initiator in combination with a reducing agent such as sodium sulfite, sodium hydrogen sulfite, ferrous sulfate, and L-ascorbic acid.
    [00045] [00045] In order to control the liquid absorption characteristics of the water-absorbing resin particles, a chain transfer agent can be included in the aqueous solution of the water-soluble ethylene unsaturated monomers used for the polymerization. Examples of the chain transfer agent include hypophosphites, thiols, thioic acids, secondary alcohols, and amines.
    [00046] [00046] Examples of a hydrocarbon dispersion medium include aliphatic chain hydrocarbons such as n-hexane, n-heptane, 2-methylhexane, 3-methylhexane, 2,3-dimethylpentane, 3-ethylpentane, and n -octane; alicyclic hydrocarbons such as cyclohexane, methyl cyclohexane, cyclopentane, methyl cyclopentane, trans-1,2-dimethylcyclopentane, cis-1,3-dimethylcyclopentane, and trans-1,3-dimethylcyclopentane; and aromatic hydrocarbons such as benzene, toluene, and xylene. These hydrocarbon dispersion means can be used alone or in combination of two or more types thereof. The hydrocarbon dispersion medium may include at least one compound selected from the group consisting of a chain aliphatic hydrocarbon having 6 to 8 carbon atoms and an alicyclic hydrocarbon having 6 to 8 carbon atoms. From the point of view that the water / oil type reverse phase suspension state is good, water-absorbing resin particles having excellent water absorption rate are easily obtained with suitable particle diameters and easily commercially available, and the quality is stabilized, the hydrocarbon dispersion medium can include n-heptane, cyclohexane, or both. In addition, from the same point of view, as a mixture of the hydrocarbon dispersion media, for example, Exxsol Heptane (manufactured by ExxonMobil Chemical: containing 75% to 85% of n-heptane and isomers thereof), which is commercially available, can be used.
    [00047] [00047] From the point of view that the heat of polymerization is appropriately removed and easy control over a temperature of polymerization is allowed, the amount of the hydrocarbon dispersion medium to be used is preferably 100 to 1,000 parts by mass , more preferably 150 to 800 parts by weight, and even more preferably 200 to 700 parts by weight, with respect to 100 parts by weight of the water-soluble ethylene unsaturated monomers. With the amount of hydrocarbon dispersion medium to be used of 100 parts by mass or more, there is a tendency that easy control over the polymerization temperature is allowed. With the amount of hydrocarbon dispersion medium to be used of 1,000 parts by mass or less, there is a tendency for polymerization productivity to be improved, which is economical.
    [00048] [00048] Internal cross-linking occurs by self-cross-linking with polymerization. The liquid absorption characteristics of the water-absorbing resin particles can be controlled by carrying out the internal crosslinking additionally with the use of an internal crosslinking agent. Examples of the internal cross-linking agent to be used include compounds having two or more reactive functional groups, such as poly- or di-tracid esters of polyols such as ethylene glycol, propylene glycol, trimethylol propane, glycerin, polyoxyethylene glycol, polyoxypropylene glycol, and polyglycerin; unsaturated polyesters obtained by reacting the above polyols with unsaturated acids such as maleic acid and fumaric acid; bis (meth) acrylamides such as N, N'-methylenebis (meth) acrylamide; (meth) acrylic di- or triacid esters obtained by reacting a polyepoxide with (meth) acrylic acid; carbamyl di (meth) acrylate esters obtained by reacting a polyisocyanate such as tolylene diisocyanate and hexamethylene diisocyanate with hydroxyethyl (meth) acrylate; compounds having two or more polymerizable unsaturated groups, such as allylated starch, allylated cellulose, diallyl phthalate, N, N ', N "-trialyl isocyanate, and divinyl benzene; polyglycidyl compounds such as (poly) ethylene glycol diglycidyl ether, (poly) diglycidyl ether glycerin, (poly) glycerin triglycidyl ether, (poly) propylene glycol polyglycidyl ether, and polyglycerol polyglycidyl ether; haloepoxy compounds such as epichlorohydrin, epibromohydrin, and α-methyl epichlorohydrin; and isocyanate compounds such as 2,4-tolylene diisocyanate and hexamethylene diisocyanate These crosslinking agents can be used alone or in combination of two or more of the same types.
    [00049] [00049] From the point of view that the water solubility properties are suppressed through the appropriate crosslinking of the obtained polymer and sufficient amounts of absorption are displayed, the amount of the internal crosslinking agent is preferably from 0 to 0.03 mol , more preferably 0 to 0.01 mol, and even more preferably 0 to 0.005 mol, per mol of the water-soluble ethylene unsaturated monomer.
    [00050] [00050] Reverse phase suspension polymerization can be carried out in a water-in-oil system by mixing water-soluble ethylene unsaturated monomers and a water-soluble radical polymerization initiator, and as desired, an internal cross-linking agent, a surfactant, a hydrocarbon dispersion medium, or the like, and heating the mixture with stirring. The order of addition of the respective components and the like can be appropriately adjusted. For example, it is preferable to mix a surfactant with a hydrocarbon dispersion medium beforehand, while mixing a water-soluble radical polymerization initiator, an internal cross-linking agent, and water-soluble ethylene unsaturated monomers beforehand, and mix separately these liquids mixed thus each obtained, thus initiating the polymerization. In addition, a multistage polymerization method in which the aqueous monomer solution is added multiple times can be used.
    [00051] [00051] A temperature for the polymerization reaction varies depending on the type of a water-soluble radical polymerization initiator to be used, but from the point of view that the reaction is carried out gently by easily removing the heat of polymerization while doing the polymerization proceeds quickly and shortens the polymerization time and thus improves the economic efficiency, the temperature is preferably 20ºC to 110ºC, and more preferably 40ºC to 90ºC. The reaction time is normally 0.5 to 4 hours. The termination of the polymerization reaction can be confirmed, for example, by stopping an increase in temperature within the reaction system. Thus, water-absorbing resin particles are normally obtained in the state of a hydrated gel.
    [00052] [00052] After the polymerization reaction, the hydrated gel obtained can be subjected to intermediate cross-linking. Through intermediate crosslinking, the degree of crosslinking of the hydrated gel can be increased to improve the liquid absorption characteristics more preferably. Intermediate crosslinking can be carried out by adding a crosslinking agent to the hydrated gel after the polymerization reaction, followed by heating.
    [00053] [00053] Examples of the crosslinking agent for carrying out the intermediate crosslinking include polyols such as ethylene glycol, propylene glycol, 1,4-butanediol, trimethylolpropane, glycerin, polyoxyethylene glycol, polyoxypropylene glycol, and polyglycerin; compounds having 2 or more epoxy groups, such as (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, and (poly) glycerine diglycidyl ether; haloepoxy compounds such as epichlorohydrin, epibromohydrin, and α-methyl epichlorohydrin; compounds having two or more isocyanate compounds such as 2,4-tolylene diisocyanate and hexamethylene diisocyanate; oxazoline compounds such as 1,2-ethylenebisoxazoline; carbonate compounds such as ethylene carbonate; and hydroxyalkylamide compounds such as bis [N, N-di (β-hydroxyethyl)] adipamide. Among these, polyglycidyl compounds such as (poly) ethylene glycol diglycidyl ether, (poly) glycerin diglycidyl ether, (poly) glycerin triglycidyl ether, (poly) propylene glycol polyglycidyl ether, and polyglyceryl polyglycidyl ether are preferable. These crosslinking agents can be used alone or in combination of two or more types thereof.
    [00054] [00054] From the points of view the hydrated gel obtained is appropriately crosslinked, and in an appropriate way, the water solubility properties are suppressed and good liquid absorption characteristics are displayed, the amount of the crosslinking agent used for the crosslinking intermediate is preferably 0 to 0.03 mol, more preferably 0 to 0.01 mol, and even more preferably 0 to 0.005 mol, per mol of the water-soluble ethylene unsaturated monomer.
    [00055] [00055] Subsequently, in order to remove moisture from the hydrated gel obtained, drying is carried out. Examples of the drying method include a method (a) in which azeotropic distillation is carried out by heating from the outside in the state where the hydrated gel is dispersed in a hydrocarbon dispersion medium, and the hydrocarbon dispersion medium is refluxed to removing moisture, a method (b) in which a polymer in the form of a hydrated gel is removed by decantation to perform drying under reduced pressure, and a method (c) in which a polymer in the form of a hydrated gel is separated by filtration and dried under reduced pressure. Among these, method (a) is used preferably due to simplicity in the production step.
    [00056] [00056] The control over the particle diameter of the water-absorbing resin particle can be accomplished, for example, by adjusting the rotation speed of a stirrer during the polymerization reaction or by adding an inorganic flocculation agent in powder into the system after the polymerization reaction or drying starts. There is a tendency that by adding the flocculating agent, the particle diameter of the obtained water-absorbing resin particle can be increased. Examples of the powdered inorganic flocculating agent include silica, zeolite, bentonite, aluminum oxide, talc, titanium dioxide, kaolin, clay, and hydrotalcite, and among these, from the point of view of the aggregation effect, silica, oxide aluminum, talc, or kaolin is preferable.
    [00057] [00057] In reverse phase suspension polymerization, as a method for adding the powdered inorganic flocculating agent, a method in which a powdered inorganic flocculating agent is dispersed in the same type of a hydrocarbon dispersion medium as that for use in a polymerization or water beforehand, followed by mixing in a hydrocarbon dispersion medium including a hydrated gel under agitation, is preferable.
    [00058] [00058] The amount of the powdered inorganic flocculating agent to be added is preferably 0.001 to 1 part by weight, more preferably 0.005 to 0.5 parts by weight, and even more preferably 0.01 to 0.2 parts by weight , with respect to 100 parts by mass of water-soluble ethylene unsaturated monomers. By adjusting the amount of powdered inorganic flocculating agent to be added within the above range, it is easy to obtain water-absorbing resin particles having a desired particle size distribution.
    [00059] [00059] The initial drying time mentioned above indicates, for example, a state where a water content of the hydrated gel is 50% by mass or more in the drying step after the polymerization reaction. A specific time point for adding the powdered inorganic flocculating agent according to the present embodiment is preferably a time point where the water content of the hydrated gel is 50% by weight or more, more preferably a time point at that the water content of the hydrated gel is 55% by mass or more, and even more preferably a point of time at which the water content of the hydrated gel is 60% by mass or more.
    [00060] [00060] The water content of the hydrated gel is calculated by the following equation. Water content = (Ww) ÷ (Ww + Ws) x100 [mass%] Ww: An amount of moisture in a hydrated gel calculated by adding an amount of moisture used, as desired, mixing an inorganic flocculating agent in powder, a post-crosslinking agent, and the like for an amount obtained by subtracting an amount of moisture extracted outwardly by the drying step from an amount of moisture included in the aqueous liquid prior to polymerization throughout the polymerization step. Ws: A fraction of solid calculated from quantities of materials to be introduced such as water-soluble ethylene unsaturated monomers that constitute the hydrated gel polymer, a cross-linking agent, and an initiator.
    [00061] [00061] At a certain stage of the drying step or later in the production of the water-absorbing resin particles according to the present embodiment, the surface portion of a hydrated gel is preferably cross-linked
    [00062] [00062] Examples of the post-cross-linking agent for carrying out post-cross-linking include compounds having two or more reactive functional groups. Examples of the compounds include polyols such as ethylene glycol, propylene glycol, 1,4-butanediol, trimethylolpropane, glycerin, polyoxyethylene glycol, polyoxypropylene glycol, and polyglycerin; polyglycidyl compounds such as (poly) ethylene glycol diglycidyl ether, (poly) glycerin diglycidyl ether, (poly) glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, (poly) propylene glycol polyglycidyl ether, and (poly) glycerol polyglycidyl ether; haloepoxy compounds such as epichlorohydrin, epibromohydrin, and α-methyl epichlorohydrin; isocyanate compounds such as 2,4-tolylene diisocyanate and hexamethylene diisocyanate; oxetane compounds such as 3-methyl-3-oxethane methanol, 3-ethyl-3-oxethane methanol, 3-butyl-3-oxethane methanol, 3-methyl-3-oxethane ethanol, 3-ethyl-3-oxethane ethanol, and 3-butyl-3-oxethane ethanol; oxazoline compounds such as 1,2-ethylenebisoxazoline; carbonate compounds such as ethylene carbonate; and hydroxyalkylamide compounds such as bis [N, N-di (β-hydroxyethyl)] adipamide. Among these, polyglycidyl compounds such as (poly) ethylene glycol diglycidyl ether, (poly) glycerin diglycidyl ether, (poly) glycerin triglycidyl ether, (poly) propylene glycol polyglycidyl ether, and polyglyceryl polyglycidyl ether are more preferable. These post-crosslinking agents can be used alone or in combination of two or more types thereof.
    [00063] [00063] The amount of the post-crosslinking agent cannot be absolutely determined as it varies depending on the type of the post-crosslinking agent, but the amount is commonly a ratio of 0.00001 to 0.02 mol, preferably 0, 0001 to 0.01 mol, and more preferably 0.0005 to 0.005 mol, in terms of a ratio to 1 mol of the water-soluble ethylene unsaturated monomers used for polymerization.
    [00064] [00064] From the point of view of sufficiently increasing the crosslink density on a surface portion of the water-absorbing resin particles to improve the gel resistance of the water-absorbing resin particles, the amount of the post-cross-linking agent preferably to be used is 0.00001 mol or more, and from the point of view of increasing the water holding capacity of the water-absorbing resin particles, the amount is preferably 0.02 mol or less.
    [00065] [00065] A dry product of the surface-crosslinked water-absorbent resin particles can be obtained through the distillation of water and the hydrocarbon dispersion medium by the known methods after the post-crosslinking reaction.
    [00066] [00066] The water-absorbent resin particles according to the present embodiment can be used in mixing with, for example, a gel stabilizer, a metal chelating agent, silica, or the like. The water-absorbent resin particles according to the present embodiment can be made to have a desired particle size distribution at the point of time by the production method mentioned above, but the particle size distribution can be set to a distribution of predetermined particle size by additionally performing operations such as adjusting a particle size by sorting with a sieve.
    [00067] [00067] The water-absorbent resin particles according to the present embodiment can have an average particle diameter of, for example, 250 to 850 µm, and is preferably 300 to 700 µm, and more preferably 300 to 500 µm .
    [00068] [00068] Water-absorbent resin particles in general take shapes such as a substantially spherical shape, a crushed shape, a granular shape, and aggregates thereof depending on a production process. From the point of view that the effect of the present invention is more easily obtained, the water-absorbing resin particles according to the present embodiment can be, for example, in a granular form. The granular shape in the present specification indicates that particles have a number of projections on their surfaces and can also be mentioned as a fine uneven shape. The water-absorbing resin particles according to the present embodiment can also be aggregated of granular particles.
    [00069] [00069] The water-absorbing resin particles according to the present embodiment have a high water absorption capacity even with respect to physiological saline. The water-holding capacity of the physiological saline solution of the water-absorbing resin particles according to the present embodiment can be, for example, 10 to 25 g / g or 15 to 25 g / g. By the way, the water absorption rate of physiological saline solution of the water-absorbing resin particles according to the present embodiment can be, for example, 10 seconds or less, and can also be 8 seconds or less, or 6 seconds or less. The water holding capacity of the physiological saline solution and the water absorption rate of the physiological saline solution are measured by the methods described in the Examples which will be described later.
    [00070] [00070] The water-absorbent resin particles according to the present embodiment preferably have an artificial menstrual blood absorption rate of 10 seconds or less. The rate of absorption of artificial menstrual blood can be 8 seconds or less, or 7 seconds or less. The rate of absorption of artificial menstrual blood can be, for example, 1 second or more, or 3 seconds or more. The rate of absorption of artificial menstrual blood is measured according to the method described in the Examples which will be described later.
    [00071] [00071] The water-absorbent resin particles according to the present embodiment are excellent at absorbing a viscous liquid containing a solid component such as blood, and thus, they can be applied in the fields of, for example, blood-absorbing articles disposable such as sanitary napkins and tampons, medical blood absorbent articles, injury protection agents, injury treatment agents, surgical drainage treatment agents, disposable paper diapers, and the like.
    [00072] [00072] In particular, for female sanitary napkins, it is possible to quickly absorb moisture in menstrual blood using the water-absorbent resin particles according to the present embodiment, and it is possible to expect an additional reduction in the leakage of menstrual blood already that the volume of water-absorbing resin particles is significantly increased after absorption, and thus the adhesiveness between a product and a portion close to the vaginal opening in the body is increased even in the case of fine sanitary napkins.
    [00073] [00073] The water-absorbent resin particles according to the present embodiment can be used suitably for absorbent materials. Absorbent materials can include, for example, water-absorbent resin particles and fibrous materials.
    [00074] [00074] The mass ratio of the water-absorbent resin particles in the absorbent material can be from 2% to 60%, and is preferably 10% to 30%, with respect to the total amount of the water-absorbent resin particles and the fibrous materials. The structure of the absorbent material can be, for example, in a form in which water-absorbing resin particles and fibrous materials are uniformly mixed, or can be in a form in which water-absorbing resin particles are held between formed fibrous materials in leaf form or in layer form, or in other forms.
    [00075] [00075] Examples of the fibrous material include cellulose based fibers such as finely pulverized wood pulp, cotton, cotton linter, rayon, and cellulose acetate, and synthetic fibers such as polyamides, polyesters, and polyolefins. In addition, the fibrous materials can be a mixture of the fibers mentioned above.
    [00076] [00076] Individual fibers can be bonded by adding an adhesive binder to the fibrous materials in order to improve the retention properties of form before and during the use of the absorbent materials. Examples of such an adhesive binder include hot melt synthetic fibers, hot melt adhesives, and adhesive emulsions.
    [00077] [00077] Examples of such hot melt synthetic fibers include binders of the completely melt type such as polyethylene, polypropylene, and an ethylene-propylene copolymer; and binders of the non-molten type completely formed of polypropylene and polyethylene in a side-by-side configuration or in a core and sheath configuration. In the binders of the non-melt type completely mentioned above, the polyethylene portion alone is hot melt. Examples of the hot melt adhesive include mixtures of base polymers such as an ethylene - vinyl acetate copolymer, a styrene block copolymer -
    [00078] [00078] Examples of adhesive emulsions include polymers of at least one or more monomers selected from a group consisting of methyl methacrylate, styrene, acrylonitrile, 2-ethylhexyl acrylate, butyl acrylate, butadiene, ethylene, and vinyl acetate . These adhesive binders can be used alone or in combination with two or more types thereof.
    [00079] [00079] The absorbent article according to the present embodiment includes the water-absorbent resin particles mentioned above. The absorbent article according to the present embodiment includes, for example, a liquid-permeable sheet, the absorbent material, and a liquid-impermeable sheet in that order. The absorbent article can be applied, for example, to disposable blood absorbent articles such as sanitary napkins.
    [00080] [00080] Examples of materials for liquid-permeable sheets include non-woven fabrics formed from polyolefins such as polyethylene and polypropylene, polyesters, polyamides, and porous synthetic resin films or the like. Examples of materials for liquid impermeable sheets include synthetic resin films formed from polyethylene, polypropylene, ethylene vinyl acetate, polyvinyl chloride, or the like; films formed from composites of these synthetic resins and non-woven fabrics; and films formed from composites of these synthetic resins with woven fabrics. These liquid impermeable sheets can also be provided with vapor transmission properties.
    [00081] [00081] The absorbent material and the absorbent article may additionally include amorphous silica, deodorants, antibacterial agents, fragrances, and the like. EXAMPLES
    [00082] [00082] Hereinafter, the present invention will be described in more detail with reference to the Examples, but the present invention is not limited to these Examples.
    [00083] [00083] [Evaluation Test on Water-Absorbing Resin Particles]
    [00084] [00084] The water-absorbent resin particles obtained in Examples 1 to 3 and Comparative Examples 1 to 4 below were subjected to each test shown below and evaluated. Hereinafter, each of the assessment test methods will be described. (1) Preparation of Artificial Menstrual Blood
    [00085] [00085] The respective following components were mixed in ion exchange water and dissolved in the same one that NaCl was at 1.00% by mass, Na2CO3 was at 0.40% by mass, glycerin was at 10.00% by mass, and carboxymethyl cellulose having a molecular weight of 25,000 was 0.45% by weight to obtain artificial test menstrual blood. (2) Water retention capacity of saline
    [00086] [00086] A cotton bag (Cottonbroad No. 60, 100 mm wide x 200 mm long) in which 2.0 g of water-absorbent resin particles were added was placed in a beaker having a capacity of 500 ml. 500 g of an aqueous solution of 0.9% by weight sodium chloride (physiological saline) was poured into the cotton bag with the water-absorbing resin particles in it at once such that the powder was not added, and the top of the cotton bag was closed with a rubber band and left to rest for 30 minutes so that the water-absorbing resin particles were swelled. The cotton bag after a period of 30 minutes was dehydrated for 1 minute using a dehydrator (manufactured by Kokusan Co., Ltd., product number: H-122) which was adjusted to a centrifugal force of 167 G, and the mass Wa (g) of the cotton bag containing the swollen gel after dehydration was measured. The same operation was repeated while adding the water-absorbing resin particles and the mass Wb (g) of the empty cotton bag when wetting was measured, and the water retention capacity of physiological saline solution was calculated by the following equation: Capacity physiological saline water retention rate (g / g) = [Wa-Wb] / 2.0 (3) Physiological Saline Water Absorption Rate
    [00087] [00087] The rate of absorption of saline water was measured in a controlled room at 25◦C ± 1◦C. 50 ± 0.1 g of physiological saline that was added in a beaker having a capacity of 100 ml was adjusted to a temperature of 25◦C ± 0.2◦C in a thermostatic bath and then stirred at 600 rpm with a bar magnetic stirrer (8 mmΦx30 mm without a ring) to generate a vortex. 2.0 ± 0.002 g of water-absorbing resin particles were added to the physiological saline solution at once, and a time (s) until the vortex disappears and the liquid surface is flat after adding the absorbent resin particles of water. water was measured. Time was taken as the water absorption rate of physiological saline from the water-absorbing resin particles. (4) Artificial Menstrual Blood Absorption Rate
    [00088] [00088] The rate of absorption of artificial menstrual blood was measured in the same operation as the rate of absorption of physiological saline, except that artificial menstrual blood adjusted to 37◦C ± 1◦C was used instead of physiological saline as a test solution. (5) Average Particle Diameter (Particle Size Distribution)
    [00089] [00089] Standard JIS sieves were mounted in sequence in descending order, with a sieve with a mesh size of 850 µm, a sieve with a mesh size of 500 µm, a sieve with a mesh size of 425 µm, a sieve with a mesh size of 300 µm, a sieve with a mesh size of 250 µm, a sieve with a mesh size of 180 µm, a sieve with a mesh size of 150 µm, and a receiving tray.
    [00090] [00090] 50 g of water-absorbent resin particles were fed to the top sieve of the combination and stirred for 20 minutes using a Ro-Tap type shaker to conduct the classification. After classification, the mass of the water-absorbing resin particles that remain in each sieve was calculated as a percentage of the total amount to determine a particle size distribution. The values calculated on the screens were integrated in descending order of particle diameters with respect to the particle size distribution, and the relationship between the mesh size of the screen and the integrated value of the mass percentages of the water-absorbing resin particles that remain in the sieve was plotted on a logarithmic probability paper. The points plotted on the probability paper were connected by straight lines, and thus, the particle diameter corresponding to 50% by mass of the integrated mass percentage was taken as the average particle diameter.
    [00091] [00091] The ratio of the presence of water-absorbing resin particles having a particle diameter of more than 250 µm and 850 µm or less is a sum of the reasons for the water-absorbing resin particles that remain in the sieves having mesh sizes 500 µm, 425 µm, 300 µm, and 250 µm, and similarly, the presence ratio of water-absorbing resin particles having a particle diameter of 250 µm or less is a numerical value obtained by adding all the ratios the water-absorbing resin particles that remain in the sieves having mesh sizes of 180 µm and 150 µm, and the receiving tray. (6) Artificial Menstrual Blood Swelling Test
    [00092] [00092] 1.0 g of water-absorbing resin particles were weighed and placed in a measuring cylinder (1 ml scale) with an internal diameter of 27 mm and a capacity of 100 ml, and arranged such that the particles of water-absorbent resin becomes uniform across the cylinder. Next, 10 ml of artificial menstrual blood (with the density of artificial menstrual blood being 1.03 g / cm3) was injected into the cylinder at once. At a point in time after a period of 60 seconds or 300 seconds from injection, a higher point in the volumes of the swollen water-absorbent resin particles was measured and the numerical value was read in a 1 ml unit and taken as one volume (ml) after swelling. An artificial menstrual blood volume increase rate was calculated according to Equation (I) below. Increase rate of artificial menstrual blood volume (%) = (A-B) / Bx100 ... (I), A ... Volume (ml) after swelling B ... Volume (ml) of artificial menstrual blood injected
    [00093] [00093] The results are shown in Table 2 and Fig. 1. In Fig. 1, (1), (2), and (3) represent the water-absorbing resin particles after swelling in the blood swelling tests artificial menstrual in Example 1, Comparative Example 1, and Comparative Example 2, respectively. (7) Pure Water Swelling Test
    [00094] [00094] Through the same operation as in the artificial menstrual blood swelling test, except that pure water was used instead of artificial menstrual blood as a test solution and the injection amount was changed to 30 ml, an increase rate volume of pure water was determined. The results are shown in the Table
    [00095] [00095] [Example 1] A separable cylindrical round bottom flask including four-position sidewall deflectors (deflector width: 7 mm) with an internal diameter of 110 mm and a capacity of 2 L, which has been equipped with a condenser reflux, a drip funnel, and a nitrogen gas introduction tube, and a stirrer having stirring blades including two sets of four inclined blade blades (surface treated with fluororesin) with a blade diameter of 50 mm, was prepared. 660 ml of n-heptane as a petroleum-based hydrocarbon dispersion medium was placed in the flask, 0.984 g of sorbitan monolaurate (trade name: Nonion LP-20R, HLB value of 8.6, manufactured by NOF Corporation) was added to it, and the mixture was heated to 50 ° C. Sorbitana monolaurate was dissolved in n-heptane by heating, and then the internal temperature was lowered to 40◦C.
    [00096] [00096] 92 g (1.02 mol) of an 80% by weight aqueous acrylic acid solution were placed in an Erlenmeyer flask having a capacity of 500 ml, and 146 g of a 21% by weight aqueous sodium hydroxide solution were added in drops to it under ice cooling from the outside to neutralize 75 mol% with respect to acrylic acid. Then 0.101 g (0.374 mmol) of potassium persulfate as a radical polymerization initiator was added to the partially neutralized aqueous acrylic acid solution thus obtained, thereby preparing an aqueous monomer solution.
    [00097] [00097] The aqueous monomer solution was added to the separable vial, and after the interior of the system had been sufficiently replaced with nitrogen, a rotary speed of the stirrer was set to 700 rpm, and the vial was immersed in a water bath in 70◦C and maintained for 60 minutes.
    [00098] [00098] Next, 0.092 g of amorphous silica (Carplex # 80, manufactured by Evonik Degussa Japan, Inc.) as a powdered inorganic flocculating agent, which was dispersed in 100 g of n-heptane beforehand, was added to a polymerization solution containing the hydrated gel produced, n-heptane, and a surfactant, and mixed for 10 minutes. Then, the flask containing the reaction solution was immersed in an oil bath in 125◦C, and 104 g of water were extracted from the system while n-heptane was refluxed by azeotropic distillation with n-heptane and water. Then, 8.28 g (0.95 mmol) of a 2% by weight aqueous solution of ethylene glycol diglycidyl ether as a post-crosslinking agent was added to it and the mixture was maintained at an internal temperature of 80◦C ± 2◦C for 2 hours.
    [00099] [00099] Next, n-heptane was evaporated and the residue was dried to obtain a dry product. The dried product was passed through a sieve having a mesh size of 850 µm to obtain 90.5 g of water-absorbing resin particles. The water-absorbent resin particles obtained were in the form in which granular (very irregular) particles were aggregated. The water-absorbent resin particles obtained were evaluated according to each test method mentioned above.
    [000100] [000100] [Example 2] A separable bottle with a cylindrical rounded bottom including four-position sidewall deflectors (deflector width: 7 mm) with an internal diameter of 110 mm and a capacity of 2 L, which has been equipped with a condenser reflux, a drip funnel, and a nitrogen gas introduction tube, and a stirrer having stirring blades including two sets of four inclined blade blades (surface treated with fluororesin) with a blade diameter of 50 mm, was prepared. 660 ml of n-heptane as a petroleum-based hydrocarbon dispersion medium was placed in the flask, 1.10 g of sorbitan monolaurate (trade name: Nonion LP-20R, HLB value of 8.6, manufactured by NOF Corporation ) was added to it, and the mixture was heated to 50 ° C. Sorbitana monolaurate was dissolved in n-heptane by heating, and then the internal temperature was lowered to 40◦C.
    [000101] [000101] 92 g (1.02 mol) of an 80% by weight aqueous acrylic acid solution were placed in an Erlenmeyer flask having a capacity of 500 ml, and 146.0 g of a 21% aqueous sodium hydroxide solution in bulk they were added in drops to it under ice cooling from the outside to carry out the neutralization of 75 mol% with respect to acrylic acid. Then 0.101 g (0.374 mmol) of potassium persulfate as a radical polymerization initiator was added to the partially neutralized aqueous acrylic acid solution thus obtained, thereby preparing an aqueous monomer solution.
    [000102] [000102] The aqueous monomer solution was added to the separable flask, and after the interior of the system was substantially replaced with nitrogen, a rotary speed of the stirrer was set to 700 rpm, and the flask was immersed in a 70 ° water bath. ◦C and maintained for 60 minutes. 0.41 g (0.047 mmol) of a 2% by weight aqueous solution of ethylene glycol diglycidyl ether as an intermediate crosslinking agent was added and the mixture was kept at 75 ° C for 30 minutes.
    [000103] [000103] Next, 0.092 g of amorphous silica (Carplex # 80, manufactured by Evonik Degussa Japan, Inc.) as a powdered inorganic flocculating agent was added to a polymerization solution containing the produced hydrated gel, n-heptane, and a surfactant under agitation, and sufficiently mixed. Then, the flask containing the reaction solution was immersed in an oil bath in 125◦C, and 109 g of water was extracted from the system while n-heptane was refluxed by azeotropic distillation with n-heptane and water. Then, 24.84 g (2.85 mmol) of a 2% by weight aqueous solution of ethylene glycol diglycidyl ether as a post-crosslinking agent was added to it and the mixture was maintained at an internal temperature of 80◦C ± 2◦C for 2 hours.
    [000104] [000104] Next, n-heptane was evaporated and the residue was dried to obtain a dry product. The dried product was passed through a sieve having a mesh size of 850 µm to obtain 90.3 g of water-absorbing resin particles. The water-absorbent resin particles obtained were evaluated according to each test method mentioned above.
    [000105] [000105] [Example 3] The same treatment as in Example 2, except that in Example 3, 111 g of water was extracted from the system while n-heptane was refluxed by azeotropic distillation with n-heptane and water, and the amount of a 2% by weight aqueous solution of ethylene glycol diglycidyl ether as a post-crosslinking agent to be added was changed to 41.40 g (4.75 mmol), it was carried out to obtain 88.9 g of absorbent resin particles from Water. The water-absorbent resin particles obtained were evaluated according to each of the test methods mentioned above.
    [000106] [000106] [Comparative Example 1] 70 g of an 80% by weight aqueous acrylic acid solution were placed in an Erlenmeyer flask having a capacity of 500 ml, and 111.1 g of a 21% by weight sodium hydroxide solution were added in drops to it under ice-cooling to perform 75 mol% neutralization with respect to acrylic acid. Then 0.084 g of potassium persulfate as a radical polymerization initiator was added to the partially neutralized aqueous acrylic acid solution thus obtained.
    [000107] [000107] [0104] 550 ml of n-heptane as a petroleum-based hydrocarbon dispersion medium and 0.84 g of sorbitan monolaurate (trade name: Nonion LP-20R, HLB value of 8.6, manufactured by NOF Corporation) as a surfactant were added to a 1.5 L four-neck cylindrical round-bottomed flask which was equipped with a stirrer, a reflux condenser, a drip funnel, and an inlet tube. nitrogen gas, and the mixture was heated to 50◦C. Sorbitana monolaurate was dissolved in n-heptane by heating, and then the internal temperature was lowered to 40◦C. Then the aqueous solution of partially neutralized acrylic acid mentioned above was added to it to prepare a suspension in reverse phase, and after the interior of the system was replaced with nitrogen, a rotating speed of the stirrer was set to 700 rpm, and the flask was immersed in a 70 ° C water bath and kept for 3 hours.
    [000108] [000108] Next, the water was removed from the azeotropic mixture of n-heptane and water by reheating. Then, 0.2 g of ethylene glycol diglycidyl ether as a surface crosslinking agent was added to it to perform a crosslinking reaction. After the crosslinking reaction, the mixture was dried by distillation of n-heptane and water in the system and passed through a sieve having a mesh size of 850 µm to obtain 70.3 g of water-absorbing resin particles. The water-absorbent resin particles obtained were evaluated according to each of the test methods mentioned above.
    [000109] [000109] [Comparative Example 2] The same treatment as Example 2, except that 129 g of water was extracted from the system while n-heptane was refluxed by azeotropic distillation with n-heptane and water, and then the amount of an aqueous solution of ethylene glycol diglicidyl ether 2% by mass as a post-crosslinking agent to be added was changed to 4.14 g (0.48 mmol), it was carried out to obtain 90.0 g of water-absorbing resin particles. The water-absorbent resin particles obtained were evaluated according to each of the test methods mentioned above.
    [000110] [000110] [Comparative Example 3] The same treatment as in Example 2, except that 91 g of water was extracted from the system while n-heptane was refluxed by azeotropic distillation with n-heptane and water, and then the amount of a solution 2% by weight aqueous ethylene glycol diglycidyl ether as a post-crosslinking agent to be added was changed to 4.14 g (0.48 mmol), was performed to obtain 90.3 g of water-absorbing resin particles. The water-absorbent resin particles obtained were evaluated according to each of the test methods mentioned above.
    [000111] [000111] [Comparative Example 4] The same treatment as in Example 2, except that a powdered inorganic flocculating agent was not added after the intermediate crosslinking reaction, the reaction solution was heated in an oil bath at 125ºC, 125 g of water was extracted from the system while n-heptane was refluxed by azeotropic distillation with n-heptane and water, and then 16.56 g (1.90 mmol) of a 2% by weight aqueous solution of ethylene glycol diglycidyl ether as a post-crosslinking agent was added, it was performed to obtain 88.9 g of water-absorbing resin particles. The water-absorbent resin particles obtained were evaluated according to each of the test methods mentioned above. [Table 1] Capacity Distribution Rate particle size Rate of more retention absorption absorption of the water diameter of the Solution of blood 250 250 medium saline solution menstr µm or µm and physiological saline minus 850 part physiological ca artifi c (%) µm or single cell (g / g) minus cial (µm) (g / g) (s) (%) Example 1 18 4 6 91 9 420 Example 2 20 4 6 94 6 397 Example 3 19 4 4 83 17 351 Example 21 2 4 24 76 199 comparative 1 Example 38 4 7 92 8 369 comparative 2 Example 22 2 4 81 19 330 comparative 3 Example 23 2 4 57 43 266 comparative 4
    [000112] [000112] As shown in Table 2, the swelling rates of the water-absorbing resin particles obtained in the Examples were high, and among these, the swelling rates in a case of absorption of artificial menstrual blood were good.
    [000113] [000113] [Evaluation of the absorbent article] (1) Preparation of absorbent material and absorbent article
    [000114] [000114] Absorbent materials and absorbent articles were prepared using the water-absorbent resin particles obtained in Examples 1 to 3 and Comparative Examples 1 to 4. 0.48 g of water-absorbent resin particles and 1.92 g of shredded pulp (Rayfloc, manufactured by Rayonier) were used and uniformly mixed using a sheet-by-air technique to prepare a core of sheet-like absorbent material having a size of 20 cm x 6 cm. Then, an absorbent material was prepared by pressing the absorbent material core while placing the core between two pieces of tissue paper, each of which is the same size as the absorbent material core and a base weight of 16 g / m2 by applying a load of 196 kPa for 30 seconds across the core. In addition, a porous liquid-permeable sheet of the air passing type which was made of polyethylene - polypropylene and had a base weight of 22 g / m2 was placed on the upper surface of the absorbent material, a liquid impermeable sheet which was made of polyethylene and had the same size and base weight was arranged on the bottom surface of the absorbent material, and then the absorbent material was positioned between them to obtain an absorbent article having a base weight of the water-absorbent resin particles of 40 g / m2 and a base weight of the hydrophilic fibers of 160 g / m2. (2) Test Blood
    [000115] [000115] As a test blood, defibrinated horse blood (hematocrit value of 40%, manufactured by Nippon Biotest Laboratories Inc.) was used. (3) Blood Infiltration Test (Absorbent material)
    [000116] [000116] First, an absorbent article was placed on a horizontal platform. A measuring device provided with a liquid injection cylinder having an internal diameter of 2 cm was placed in the central portion of the absorbent article, 7 ml of a test blood was poured into the cylinder at once, and a necessary time for the blood test on the cylinder from the introduction of the blood to disappear completely was measured using a stopwatch and taken as a first rate of blood infiltration (s). In 10 minutes after the first introduction of the test blood, 7 ml of the test blood was introduced into the cylinder again and the same operation was performed to mediate the second rate of blood infiltration (s). The results are shown in Table 3. [Table 3]
    [000117] [000117] As shown in the results in Table 3, absorbent articles using the water absorbent resin particles obtained in Examples 1 to 3 had good blood infiltration rates, and in particular, excellent blood infiltration rates in the second measurement , if compared to absorbent articles prepared using the water-absorbent resin particles obtained in Comparative Examples.
    权利要求:
    Claims (5)
    [1]
    1. Water-absorbing resin particles characterized by the fact that they comprise a cross-linked polymer comprising a monomer unit derived from a water-soluble ethylene unsaturated monomer, at which an artificial menstrual blood volume increase rate as measured in an artificial menstrual blood swelling test conducted in the following order of i), ii), and iii) is 70% or more: i) place 1.0 g of water-absorbing resin particles in a measuring cylinder with a internal diameter of 27 mm, ii) inject 10 ml of artificial menstrual blood into the cylinder at once to swell the water-absorbing resin particles, and iii) measure, a volume (A) of the swollen water-absorbing resin particles after a 60 seconds from the injection and calculate an artificial menstrual blood volume increase rate according to Equation (I) below: Artificial menstrual blood volume increase rate (%) = (AB) / Bx1 00 ... (I) A ... Volume (ml) of swollen water-absorbing resin particles B ... Volume (ml) of injected artificial menstrual blood.
    [2]
    2. Water-absorbing resin particles according to claim 1, characterized in that a ratio of particles having a particle diameter of more than 250 µm and 850 µm or less is 70% by weight or more and a particle ratio having a particle diameter of 250 µm or less is 20% by mass or less, with respect to the total amount of water-absorbing resin particles.
    [3]
    3. Water-absorbing resin particles according to claim 1 or 2, characterized by the fact that an artificial menstrual blood absorption rate is 10 seconds or less.
    [4]
    Water-absorbing resin particles according to any one of claims 1 to 3, characterized in that the water-holding capacity of the physiological saline solution is 10 to 25 g / g.
    [5]
    5. Absorbent article characterized by the fact that it comprises the water-absorbing resin particles as defined in any one of claims 1 to 4.
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    同族专利:
    公开号 | 公开日
    JPWO2018181565A1|2020-02-06|
    CN110446726A|2019-11-12|
    WO2018181565A1|2018-10-04|
    US20200038838A1|2020-02-06|
    EP3604360A4|2020-11-18|
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    法律状态:
    2021-11-03| B350| Update of information on the portal [chapter 15.35 patent gazette]|
    优先权:
    申请号 | 申请日 | 专利标题
    JP2017-070908|2017-03-31|
    JP2017070908|2017-03-31|
    PCT/JP2018/012957|WO2018181565A1|2017-03-31|2018-03-28|Water-absorbent resin particle|
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