Pulp sheet for fluff pulp, fluff mat and absorptive article

Abstract

To provide a pulp sheet for fluff pulp, for producing fluff pulp (fluff mat) capable of suppressing skin rash.SOLUTION: The present invention relates to a pulp sheet for fluff pulp, with the pH of a hot-water extraction liquid extracted therefrom, measured according to JIS P 8133 2:2013 being in a range of 7.0 to 9.5. The present invention also relates to a fluff mat and an absorptive article formed from the pulp sheet for fluff pulp.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a pulp sheet for fluff pulp, a fluff mat, and an absorbent article.

Background Art

[0002] Fluff pulp is obtained by defibrating wood pulp until it becomes cotton-like. Fluff pulp is used as a water-absorbing material in absorbent articles such as disposable diapers and sanitary napkins.

[0003] Conventionally, fluff pulp used in absorbent articles has been produced from softwood pulp with good defibratability (for example, Patent Document 1). In Patent Document 1, fluff pulp is obtained by defibrating raw pulp (softwood kraft pulp) with a moisture content of 35% or less by mechanical treatment.

[0004] Further, Patent Document 2 discloses a pulp sheet for fluff pulp containing hardwood kraft pulp and softwood kraft pulp. Here, it has been studied to obtain a pulp sheet for fluff pulp that can reduce the amount of backflow of the absorbed liquid and suppress skin irritation by setting the content ratio of hardwood kraft pulp and softwood kraft pulp within a predetermined range.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] As described above, pulp sheets for fluff pulp containing hardwood kraft pulp or softwood kraft pulp are known. However, when fluff pulp (fluff mat) is produced from conventional pulp sheets for fluff pulp and used, for example, as a component of a diaper, skin rash may occur, and improvement has been demanded.

[0007] Therefore, the present inventors have proceeded with studies for the purpose of providing a pulp sheet for fluff pulp capable of suppressing skin rash in order to solve such problems of the prior art.

Means for Solving the Problems

[0008] Examples of specific aspects of the present invention are shown below.

[0009] [1] A pulp sheet for fluff pulp, wherein the pH of the hot water extract measured according to JIS P 8133-2:2013 is 7.0 to 9.5. [2] The pulp sheet for fluff pulp according to [1], wherein the ISO whiteness measured according to JIS P 8148:2018 is 80% or more. [3] The pulp sheet for fluff pulp contains softwood pulp, The pulp sheet for fluff pulp according to [1] or [2], wherein the content of hardwood pulp with respect to all pulp components in the pulp sheet for fluff pulp is 30% by mass or less. [4] The pulp sheet for fluff pulp contains softwood pulp, The pulp sheet for fluff pulp according to any one of [1] to [3], wherein the content of hardwood pulp with respect to all pulp components in the pulp sheet for fluff pulp is 15% by mass or less. [5] A fluff mat formed from the pulp sheet for fluff pulp according to any one of [1] to [4]. [6] Add 20 parts by mass of artificial urine containing 1.94% by mass of urea, 0.8040% by mass of sodium chloride, 0.2045% by mass of magnesium sulfate heptahydrate, and 0.0835% by mass of calcium chloride dihydrate to 5 parts by mass of the fluff mat, and let it stand at 40 °C for 1 hour in a sealed state. The fluff mat according to [5], wherein the pH of the squeezed liquid of the fluff mat is 6.6 or higher. [7] An absorbent article comprising the fluff mat according to [5] or [6].

Effect of the Invention

[0010] According to the present invention, a pulp sheet for fluff pulp for producing fluff pulp (fluff mat) capable of suppressing skin rash can be obtained.

Brief Description of the Drawings

[0011]

Figure 1

Embodiments for Carrying Out the Invention

[0012] Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be based on typical embodiments or specific examples, but the present invention is not limited to such embodiments. In this specification, the numerical range represented by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value.

[0013] (Pulp Sheet for Fluff Pulp) This embodiment relates to a pulp sheet for fluff pulp, wherein the pH of the hot water extract measured in accordance with JIS P 8133-2:2013 is 7.0 to 9.5. In this specification, "fluff pulp" means defibrated pulp, which means fiberized or shredded pulp. Also, the "pulp sheet for fluff pulp" is a pulp sheet before defibration used for manufacturing fluff pulp. That is, by defibrating the "pulp sheet for fluff pulp", "fluff pulp" is obtained, and what is formed by shaping the "fluff pulp" into a sheet form is called a "fluff mat". In this embodiment, the "pulp sheet for fluff pulp" is obtained, for example, by papermaking a slurry containing raw material pulp.

[0014] In this embodiment, the pulp sheet for fluff pulp is subjected to hot water treatment by the method described in JIS P 8133-2:2013, and the pH of the obtained hot water extract is 7.0 to 9.5. More specifically, 2 g of the pulp sheet for fluff pulp is added to 100 ml of deionized water, and after continuing boiling for 1 hour, it is cooled to 25°C, and a solution obtained by filtering the content with a glass filter and adding a 1 mol / L potassium chloride solution is used as the hot water extract, and the pH is measured. The pH of the hot water extract is preferably 7.1 or more, more preferably 7.2 or more, and even more preferably 7.3 or more. Also, the pH of the hot water extract is preferably 9.4 or less, more preferably 9.3 or less, and even more preferably 9.2 or less.

[0015] In this embodiment, for example, in the manufacturing process of the pulp sheet for fluff pulp, after bleaching the pulp raw material, it is washed and subjected to a heating treatment under predetermined conditions, whereby the pH of the above-described hot water extract can be made within a predetermined range. More specifically, it is preferable to make the pH of the slurry during the heating treatment, for example, 2.0 to 9.0. Also, by appropriately adjusting the raw material of the pulp, it becomes easy to make the pH of the above-described hot water extract within a predetermined range.

[0016] In this embodiment, by adjusting the pH of the hot water extract obtained by subjecting the pulp sheet for fluff pulp to hot water treatment by the method described in JIS P 8133-2:2013 within the range of 7.0 to 9.5, the fluff pulp can be made neutral to alkaline. When a fluff mat formed from such fluff pulp is used as a constituent material of a diaper, it can neutralize acidic urine and suppress the occurrence of skin rash.

[0017] For example, it is preferable that the pH of the squeezed liquid of the fluff mat after allowing 20 parts by mass of artificial urine containing 1.94% by mass of urea, 0.8040% by mass of sodium chloride, 0.2045% by mass of magnesium sulfate heptahydrate, and 0.0835% by mass of calcium chloride dihydrate to be contained in 5 parts by mass of the fluff mat and allowing it to stand at 40°C for 1 hour in a sealed state is 6.6 or more, more preferably 6.8 or more, and even more preferably 7.0 or more. If the pH of the squeezed liquid of the fluff mat is within the above range, it means that the acidic urine has been neutralized, and the occurrence of skin rash is more effectively suppressed.

[0018] Also, in this embodiment, the reverse liquid return rate of the fluff mat is preferably 30% or less, more preferably 28% or less, even more preferably 26% or less, and particularly preferably 24% or less. The reverse liquid return rate of the fluff mat can be calculated by the following formula. Here, the reverse liquid return rate of the fluff mat can be calculated by measuring the weight of the liquid absorbed by the filter paper when 10 sheets of filter paper (manufactured by ADVANTEC Co., Ltd., No. 1640) are placed while being pressurized under the conditions described in the examples after allowing the fluff mat to absorb 20 g of artificial urine.

Equation

[0019] Furthermore, the pulp sheet for fluff pulp of the present embodiment has good defibering property during fluffing. In this specification, the defibering property can be evaluated by the defibering time (seconds) required until there is no undefibered material. Specifically, it can be determined that the shorter the defibering time, the better the defibering property. If the defibering property is good, the production efficiency of the fluff mat can be increased. Also, if the defibering property is good, it becomes easier to obtain a fluff mat with a lower liquid backflow rate. Further, if the defibering property is good, the amount of undefibered material in the fluff mat decreases, not only improving the appearance of the fluff mat but also enhancing the ability of the fluff mat to maintain its shape, and when used as an absorption layer of a sanitary material such as a disposable diaper, it can reduce the possibility that the shape of the absorption layer collapses due to movement during use and the absorption performance of the disposable diaper decreases.

[0020] In the pulp sheet for fluff pulp of the present embodiment, the ISO whiteness measured in accordance with JIS P 8148:2018 is preferably 80% or more, more preferably 81% or more, still more preferably 82% or more, and particularly preferably 83% or more. Also, the ISO whiteness of the pulp sheet for fluff pulp is preferably 93% or less. By setting the ISO whiteness of the pulp sheet for fluff pulp within the above range, a pulp sheet for fluff pulp with better appearance can be obtained. Also, by setting the ISO whiteness of the pulp sheet for fluff pulp within the above range, a fluff mat with high whiteness can be obtained.

[0021] The basis weight of the pulp sheet for fluff pulp of the present embodiment is not particularly limited, and it may be manufactured at a basis weight that can be manufactured in the papermaking apparatus used for papermaking. For example, the basis weight of the pulp sheet for fluff pulp is preferably 100 g / m 2 or more, more preferably 150 g / m 2 or more, and still more preferably 200 g / m 2 or more. Also, the basis weight of the pulp sheet for fluff pulp is preferably 1500 g / m 2 or less, and more preferably 1400 g / m 2It is more preferable that it is as follows, 1300 g / m 2 It is even more preferable that it is as follows. The basis weight of the pulp sheet for fluff pulp is measured in accordance with JIS P 8124:2011.

[0022] The density of the pulp sheet for fluff pulp of the present embodiment is not particularly limited, but it is preferably 0.3 g / cm 3 or more, more preferably 0.4 g / cm 3 or more, and even more preferably 0.5 g / cm 3 or more. Also, the density of the pulp sheet for fluff pulp is preferably 0.95 g / cm 3 or less, more preferably 0.90 g / cm 3 or less, and even more preferably 0.85 g / cm 3 or less. The density of the pulp sheet for fluff pulp is measured in accordance with JIS P 8118:2014.

[0023] The specific bursting strength of the pulp sheet for fluff pulp of the present embodiment measured in accordance with JIS P 8131:2009 is preferably 0.5 kPa·m 2 / g or more, more preferably 0.7 kPa·m 2 / g or more, and even more preferably 0.9 kPa·m 2 / g or more. Also, the specific bursting strength of the pulp sheet for fluff pulp is preferably 5.0 kPa·m 2 / g or less, more preferably 4.5 kPa·m 2 / g or less, and even more preferably 4.0 kPa·m 2 / g or less.

[0024] (Raw pulp) The pulp sheet for fluff pulp of the present embodiment preferably contains softwood pulp. The pulp sheet for fluff pulp of the present embodiment may contain hardwood pulp, but the content of hardwood pulp in all pulp components in the pulp sheet for fluff pulp is preferably 30% by mass or less, more preferably 20% by mass or less, still more preferably 15% by mass or less, even more preferably 10% by mass or less, and particularly preferably 5% by mass or less. Note that the content of hardwood pulp may be 0% by mass with respect to all pulp components in the pulp sheet for fluff pulp. By setting the content of hardwood pulp to 0% by mass, the defiberability of fluff pulp can be more effectively enhanced. On the other hand, by containing hardwood pulp within the above range, the liquid backflow rate of the fluff mat can be lowered.

[0025] The content of softwood pulp in all pulp components in the pulp sheet for fluff pulp is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 85% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. Also, the upper limit value of the content of hardwood pulp in all pulp components in the pulp sheet for fluff pulp is not particularly limited and may be 100% by mass.

[0026] Examples of the softwood pulp and hardwood pulp include chemical pulps such as sulfite pulp (SP), soda pulp (AP), bleached kraft pulp (BKP), unbleached kraft pulp (UKP), and oxygen bleached kraft pulp (OKP), semi-chemical pulps such as semi-chemical pulp (SCP) and chemigroundwood pulp (CGP), and mechanical pulps such as groundwood pulp (GP) and thermomechanical pulp (TMP, BCTMP). Also, the softwood pulp and hardwood pulp may be dissolving pulp (DP).

[0027] Among them, the softwood pulp contained in the pulp sheet for fluff pulp is preferably softwood kraft pulp. The raw material of the softwood kraft pulp preferably contains at least one selected from the group consisting of the genus Pinus, the genus Cryptomeria, and the genus Cryptomeria, and more preferably contains at least one selected from the group consisting of the genus Pinus and the genus Cryptomeria. Further, in the present embodiment, it is preferable to use the genus Pinus and the genus Cryptomeria in combination.

[0028] The Canadian Standard Freeness (CSF) of the softwood pulp measured according to JIS P 8121-2:2012 is preferably 600 ml or more, more preferably 640 ml or more, and further preferably 670 ml or more. However, this Canadian Standard Freeness (CSF) of the softwood pulp is a value measured for the softwood pulp before papermaking.

[0029] When hardwood pulp is contained in the pulp sheet for fluff pulp, the hardwood pulp is preferably hardwood kraft pulp. The raw material of the hardwood kraft pulp preferably contains at least one selected from the group consisting of the genus Acacia, the genus Eucalyptus, the genus Konara, the genus Fagus, and the genus Schima, and more preferably contains at least one selected from the group consisting of the genus Acacia and the genus Eucalyptus. Further, in the present embodiment, it is preferable to use the genus Acacia and the genus Eucalyptus in combination as the raw material of the hardwood kraft pulp.

[0030] The Canadian Standard Freeness (CSF) of the hardwood pulp measured according to JIS P 8121-2:2012 is preferably 370 ml or more, more preferably 400 ml or more, and further preferably 430 ml or more. However, this Canadian Standard Freeness (CSF) of the hardwood pulp is a value measured for the hardwood pulp before papermaking.

[0031] The pulp sheet for fluff pulp of the present embodiment may contain other raw material pulps in addition to softwood pulp and hardwood pulp. Examples of other raw material pulps include non-wood pulp, deinked pulp, and the like. Examples of non-wood pulp include cotton-based pulps such as cotton linter and cotton lint, bamboo pulp, non-wood-based pulps such as hemp, wheat straw, and bagasse. Examples of deinked pulp include deinked pulp made from waste paper. In this case, the content of other raw material pulps is preferably 10% by mass or less based on all pulp components in the pulp sheet for fluff pulp.

[0032] The length-weighted average fiber length of the softwood pulp used as the raw material pulp is preferably 1.50 mm or more, more preferably 1.75 mm or more, and even more preferably 2.00 mm or more. Also, the length-weighted average fiber length of the softwood pulp is preferably 3.50 mm or less, more preferably 3.20 mm or less, and even more preferably 3.00 mm or less. When hardwood pulp is included as the raw material pulp, the length-weighted average fiber length of the hardwood pulp is preferably 0.50 mm or more, more preferably 0.60 mm or more, and even more preferably 0.65 mm or more. Also, the length-weighted average fiber length of the hardwood pulp is preferably 1.20 mm or less, more preferably 1.10 mm or less, and even more preferably 1.0 mm or less. By setting the fiber lengths of the various pulps contained in the pulp sheet for fluff pulp within the above ranges, it becomes easier to control the thickness and density of the pulp sheet for fluff pulp within appropriate ranges. Also, by setting the fiber lengths of the various pulps contained in the pulp sheet for fluff pulp within the above ranges, when the pulp sheet for fluff pulp is fluffed, the reverse liquid return rate of the fluff mat can be more effectively reduced. The length-weighted average fiber lengths of the various pulps contained in the pulp sheet for fluff pulp are measured in accordance with JIS P 8226-2:2011.

[0033] (Optional component) The pulp sheet for fluff pulp may contain additives as required. Examples of the additives include softening agents, fillers, pigments, sizing agents, coagulants, oil-resistant agents, sulfate bands, yield improvers, drainage improvers, dry sheet strength enhancers, wet sheet strength enhancers, coloring pigments, anti-hydration agents, antistatic agents, sodium sulfate, surfactants, pH adjusting chemicals (such as sodium hydroxide), and the like. The pulp sheet for fluff pulp in this embodiment may contain a softening agent. By including a softening agent in the pulp sheet for fluff pulp, it is also possible to more effectively enhance the defibrillation property.

[0034] (Method for manufacturing pulp sheet for fluff pulp) The method for manufacturing the pulp sheet for fluff pulp in this embodiment preferably includes a cooking step of cooking a pulp raw material to obtain unbleached pulp, a bleaching step, a washing step, a heating treatment step, and a sheeting step. In addition to the above washing step, a dehydration washing step may be appropriately provided between each step. Further, a pre-hydrolysis step may be provided before the cooking step, an oxygen delignification step may be provided before the bleaching step, and a cold alkali step may be provided after the bleaching step. Furthermore, before the sheeting step, a beating step of beating the bleached pulp to a desired freeness may be provided.

[0035] (Cooking step) In the cooking step, the pulp raw material is cooked to obtain unbleached pulp. As the cooking method, a known method can be adopted. The cooking conditions in the cooking step are not particularly limited. For example, when using the kraft cooking method, the sulfidity of the cooking liquor is preferably 15 to 45%, the cooking temperature is preferably 130 to 170°C, the effective alkali addition rate is preferably 5 to 30% by mass per absolute dry wood mass, and the cooking time is preferably 45 to 500 minutes. The copper number of the unbleached pulp obtained through the cooking step is preferably 10 to 70.

[0036] (Pre-hydrolysis step) Before the cooking process, a pre-hydrolysis process can be provided. In the pre-hydrolysis process, hardwood or softwood is heated in the presence of water to perform pre-hydrolysis treatment. Here, the amount of water relative to the hardwood or softwood (liquid ratio: amount of water (parts by mass) / amount of hardwood or softwood (parts by mass)) is preferably 1.0 to 10, more preferably 1.5 to 8.0, still more preferably 2.0 to 7.0, and even more preferably 2.7 to 5.0. When the liquid ratio is 1.0 or more, hydrolysis proceeds sufficiently and the reaction becomes uniform, which is preferable. When the liquid ratio is 10 or less, the amount of heat required to heat to the desired temperature is reduced, which is economical and thus preferable. The method of adding water is not particularly limited, and water may be added from the outside, the water originally contained in the hardwood or softwood may be used, or when steam is used during heating, the water contained in the steam may be used. Further, chemicals that directly or indirectly assist in the hydrolysis of polysaccharides, such as alkalis, acids, chelating agents, etc., may be added together with water.

[0037] (Oxygen delignification process) In the process of manufacturing pulp sheets for fluff pulp, it is preferable to provide an oxygen delignification process after the cooking process and before the bleaching process. In the oxygen delignification process, alkaline chemicals and oxygen are added to the unbleached pulp, and lignin is decomposed at high temperature and high pressure and eluted into the alkaline chemicals. By delignifying in the oxygen delignification process, the amount of bleaching chemicals used in the subsequent multi-stage bleaching process can be reduced, and the deterioration of pulp quality can be minimized. As the oxygen delignification method, known medium-consistency methods or high-consistency methods can be directly applied, but the medium-consistency method performed at a pulp concentration of 8 to 15% by mass, which is currently widely used, is preferable.

[0038] In the oxygen delignification process by the medium consistency method, caustic soda or oxidized kraft white liquor can be used as the alkali, and as the oxygen gas, oxygen from cryogenic separation, oxygen from PSA (Pressure Swing Adsorption), or oxygen from VSA (Vacuum Swing Adsorption) etc. can be used. The oxygen gas and the alkali are added to the medium consistency pulp slurry in a medium consistency mixer. After sufficient mixing, the mixture of pulp, oxygen and alkali is sent to a reaction tower where it can be held under pressure for a certain period of time and delignified. The addition rate of the oxygen gas is preferably 0.5 to 3% by mass per absolute dry pulp mass, the alkali addition rate is preferably 0.5 to 4% by mass, the reaction temperature is preferably 80 to 120 °C, the reaction time is preferably 15 to 100 minutes, and the pulp concentration is preferably 8 to 15% by mass. Other conditions can be those known in the art and applied.

[0039] (Bleaching process) In the bleaching process, the pulp that has undergone oxygen delignification is bleached to obtain bleached pulp. The bleaching method is not particularly limited and can be bleached by known bleaching methods. Examples of the bleaching method include an ozone bleaching stage (Z), a chlorine dioxide bleaching stage (D), an alkali extraction stage (E), an oxygen bleaching stage (O), a hydrogen peroxide bleaching stage (E / P), a peracid bleaching stage (PA), an acid washing stage (a), or an acid treatment stage (A) etc. In the present embodiment, for example, it is preferably carried out in the order of D0-E / P-D1. Note that since the Z stage causes great damage to the pulp fibers and the fiber rigidity is lost, resulting in deterioration of the defibratability of the pulp sheet for fluff pulp, it is preferably not carried out.

[0040] The bleaching conditions in the D0 stage and the D1 stage are not particularly limited, but the addition rate of chlorine dioxide is preferably 0.05 to 5.0% by mass, the bleaching temperature is preferably 30 to 90 °C, the bleaching time is preferably 1 to 240 minutes, the pulp concentration is preferably 5 to 15% by mass, and the pH at the end of the reaction is preferably 2 to 6. Also, the bleaching conditions in the E / P stage are not particularly limited, but the addition rate of hydrogen peroxide is preferably 0.05 to 5.0% by mass, the bleaching temperature is preferably 30 to 90 °C, the bleaching time is preferably 1 to 240 minutes, the pulp concentration is preferably 5 to 15% by mass, and the pH at the end of the reaction is preferably 10 to 12.

[0041] (Cold alkali process) In this embodiment, the bleached pulp may be further subjected to an alkali treatment to obtain bleached pulp after the cold alkali treatment. The treatment method is not particularly limited, but caustic soda can be used as the alkali. The addition rate of caustic soda is preferably 5.0 to 20.0%, the bleaching temperature is preferably 20 to 50 °C, the bleaching time is preferably 1 to 240 minutes, and the pulp concentration is preferably 5 to 15% by mass.

[0042] (Washing process) After the bleaching process, a washing process is provided. The washing process is preferably a dewatering and washing process. In the dewatering and washing process, the bleached pulp is diluted and washed by combining dehydration. The washing method is not particularly limited, and a known washing machine can be used for washing. For example, a displacement washing method, a dilution - dehydration method, a press washing method, or a combination of these washing methods is used.

[0043] Note that the washing process is not limited to being after the bleaching process and may be provided as necessary between each process.

[0044] (Heating treatment process) In this embodiment, it is preferable to provide a heating treatment step after the bleaching step, the cold alkali step, or the washing step. In the heating treatment step, the pulp slurry is held at a temperature higher than room temperature for 30 minutes or more. The temperature of the pulp slurry in the heating treatment step is preferably 30°C or higher, more preferably 35°C or higher, and even more preferably 40°C or higher. Also, the temperature of the pulp slurry in the heating treatment step is preferably 100°C or lower, more preferably 90°C or lower, and even more preferably 80°C or lower. Note that the temperature of the pulp slurry in the heating treatment step is preferably within the above range, but it does not necessarily have to be at a constant temperature all the time.

[0045] The heating time in the heating treatment step is preferably 30 minutes or more, more preferably 1 hour or more, even more preferably 2 hours or more, still more preferably 3 hours or more, even more preferably 5 hours or more, yet even more preferably 8 hours or more, and particularly preferably 10 hours or more. Also, the heating time in the heating treatment step is preferably 100 hours or less.

[0046] The pH of the pulp slurry in the heating treatment step is preferably 2.0 or higher, more preferably 2.5 or higher, and even more preferably 3.0 or higher. Also, the pH of the pulp slurry in the heating treatment step is preferably 9.0 or lower, more preferably 8.5 or lower, and even more preferably 8.0 or lower. Note that the pH of the pulp slurry in the heating treatment step is preferably within the above range, but it does not necessarily have to be at a constant pH all the time.

[0047] In the heating treatment step, the concentration of the pulp slurry is preferably 0.5% by mass or more, more preferably 2% by mass or more, and even more preferably 5% by mass or more. Also, the concentration of the pulp slurry is preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less. Note that the concentration of the pulp slurry in the heating treatment step is preferably within the above range, but does not necessarily have to be a constant concentration at all times.

[0048] In this embodiment, by setting the heating conditions and the pH of the pulp slurry in the heating treatment step within the above ranges, it becomes easy to make the pH of the hot water extract obtained by subjecting the pulp sheet for fluff pulp to hot water treatment by the method described in JIS P 8133-2:2013 fall within the range of 7.0 to 9.5.

[0049] The heating method in the heating treatment step is not particularly limited. Steam may be directly introduced into the pulp slurry for heating, a jacket-type heating device may be used, or it may be left standing in a heating atmosphere at a temperature higher than room temperature. Also, a form of maintaining the temperature using the temperature of the pulp slurry maintained from the previous step may be used. When using a heating container in the heating treatment step, the material may be made of concrete, metal, or resin. Also, a dedicated heating tank may be used as the heating container, or the residence time until the sheeting step may be utilized.

[0050] Note that this embodiment may relate to a method for manufacturing a pulp sheet for fluff pulp, which includes a cooking step of cooking a pulp raw material to obtain uncooked pulp, a bleaching step, a washing step, a heating treatment step, and a sheeting step. In the heating treatment step, a pulp slurry with a pH of 2.0 to 9.0 is heated to 30°C or higher.

[0051] (Sheeting step) In the sheet-forming step, first, the bleached pulp obtained through the heat treatment step is dispersed in water to prepare a slurry. The pulp concentration contained in the slurry is preferably 0.01 to 10% by mass. Further, when an additive is added as necessary, it is preferable to add the additive to the slurry.

[0052] The sheet-forming step includes a step of forming a sheet from the slurry using a paper-making machine. The paper-making machine used in the papermaking step is not particularly limited. For example, a paper-making machine such as a Fourdrinier paper machine, a cylinder paper machine, a hybrid former, or a gap former can be used. Further, when forming the sheet, it may be formed into a single layer, or it may be formed by laminating a plurality of layers.

[0053] (Fluff mat) This embodiment relates to a fluff mat formed from the pulp sheet for fluff pulp described above. The fluff mat in this specification is obtained by forming the fluff pulp obtained by defibrating the above-described pulp sheet for fluff pulp into a sheet shape. When the fluff mat of this embodiment is used, for example, as a constituent material of a diaper, the occurrence of skin irritation can be suppressed. Further, the fluff mat of this embodiment has excellent water absorbency and can hold the liquid after absorbing the liquid. For this reason, the reverse return rate of the liquid is reduced in the fluff mat of this embodiment.

[0054] The conditions for defibrating the pulp sheet for fluff pulp are not particularly limited. For example, a known defibrator or crusher can be used.

[0055] The fluff mat is formed by laminating fluff pulp under an air flow. Specifically, it is formed by transporting the defibrated fluff pulp by air and laminating it on a metal mesh or a porous substrate such as a tissue or a non-woven fabric.

[0056] (Absorbent article) This embodiment may relate to an absorbent article having the fluff mat described above. Examples of the absorbent article include, for example, paper diapers, urine pads, light incontinence pads, sanitary napkins, and the like. Since the fluff mat of this embodiment can particularly neutralize acidic urine, the absorbent article is preferably a paper diaper, a urine pad, or a light incontinence pad.

Examples

[0057] The features of the present invention will be described more specifically below with reference to examples and comparative examples. The materials, amounts used, ratios, treatment details, treatment procedures, etc. shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

[0058] [Preparation of softwood pulp] [Digestion] Chips of the genus Pinus and the genus Cryptomeria were mixed at a dry mass ratio of 30:70, and then 200 g was collected in terms of dry mass and placed in an autoclave with a capacity of 2.5 liters. Kraft digestion was carried out under the conditions of a liquor ratio of 5, a sulfidity of the cooking liquor of 28%, an alkali addition rate of 22%, a digestion temperature of 165°C, and a digestion time of 120 minutes. Thereafter, the black liquor and the pulp were separated, and the pulp was refined with a flat screen equipped with a 10-cut screen plate to obtain an unbleached pulp with a kappa number of about 30.

[0059] [Oxygen delignification] 70.0 g of the unbleached pulp was collected in terms of dry mass, caustic soda was added so as to be 2.0% by mass based on the dry pulp mass, and then diluted with ion-exchanged water to adjust the pulp concentration to 10% by mass. This was placed in a heating autoclave, 99.9% commercially available compressed oxygen gas was injected to set the gauge pressure to 0.5 MPa, and oxygen delignification was carried out at 95°C for 60 minutes. The obtained pulp was diluted to 3% by mass with ion-exchanged water and then dehydrated and washed with a Buchner funnel.

[0060] [Bleaching] 60 g of kraft pulp after alkaline oxygen delignification was collected in terms of absolute dry mass, put into a plastic bag, and after adjusting the pulp concentration to 10% by mass using ion-exchanged water, chlorine dioxide was added so as to be 2.0% by mass based on the absolute dry pulp mass. This was immersed in a constant temperature water bath at 70 °C for 60 minutes to carry out the D0 stage treatment. The obtained pulp was diluted to 3% by mass with ion-exchanged water and then dehydrated and washed with a Buchner funnel. The pulp after the D0 stage was put into a plastic bag, ion-exchanged water was added to adjust the pulp concentration to 10% by mass, and then caustic soda was added so as to be 1.0% by mass and hydrogen peroxide was added so as to be 0.2% by mass based on the absolute dry pulp mass, and they were mixed well. Then, it was immersed in a constant temperature water bath at 70 °C for 90 minutes to carry out the E / P stage treatment. The obtained pulp was diluted to 3% by mass with ion-exchanged water and then dehydrated and washed with a Buchner funnel. The pulp after the E / P stage was put into a plastic bag, and after adjusting the pulp concentration to 10% by mass using ion-exchanged water, caustic soda was added so as to be 1.0% by mass and hydrogen peroxide was added so as to be 0.3% by mass based on the absolute dry pulp mass, and they were mixed well. Then, it was immersed in a constant temperature water bath at 70 °C for 90 minutes to carry out the P stage treatment. The obtained pulp was diluted to 3% by mass with ion-exchanged water and then dehydrated and washed with a Buchner funnel. The pulp after the P stage was put into a plastic bag, and after adjusting the pulp concentration to 10% by mass using ion-exchanged water, chlorine dioxide was added so as to be 0.2% based on the absolute dry pulp mass, immersed in a constant temperature water bath at 70 °C for 60 minutes, and the D1 stage bleaching was carried out. The obtained bleached softwood pulp was diluted to 3% by mass with ion-exchanged water and then dehydrated and washed with a Buchner funnel. The pulp after the D1 stage was put into a plastic bag, and after preparing the pulp concentration to 10% by mass using ion-exchanged water, chlorine dioxide was added so as to be 1.0% based on the absolute dry pulp mass, immersed in a constant temperature water bath at 70 °C for 60 minutes, and the D2 stage bleaching was carried out. The obtained bleached softwood pulp was diluted to 3% by mass with ion-exchanged water and then dehydrated and washed with a Buchner funnel to obtain a bleached softwood pulp slurry with a concentration of 10% by mass.

[0061] [Preparation of hardwood pulp] [Digestion] Chips of Eucalyptus and Acacia were mixed at a dry mass ratio of 30:70, and then 200 g was taken in terms of dry mass and placed in an autoclave with a capacity of 2.5 liters. Kraft pulping was carried out under the conditions of a liquor ratio of 5, a sulfidity of the cooking liquor of 28%, an alkali addition rate of 20%, a cooking temperature of 155 °C, and a cooking time of 120 minutes. Then, the black liquor and the pulp were separated, and the pulp was refined with a flat screen equipped with an 8-cut screen plate to obtain an unbleached pulp with a kappa number of about 18.

[0062] [Oxygen delignification] 70.0 g of the unbleached pulp was taken in terms of dry mass, caustic soda was added so that it was 2.0% by mass based on the dry pulp mass, and then it was diluted with ion-exchanged water to adjust the pulp concentration to 10% by mass. This was placed in a heated autoclave, 99.9% commercially available compressed oxygen gas was injected to make the gauge pressure 0.5 MPa, and oxygen delignification was carried out at 95 °C for 60 minutes. The obtained pulp was diluted to 3% by mass with ion-exchanged water and then dehydrated and washed with a Buchner funnel.

[0063] [Bleaching] 60 g of the kraft pulp after alkali oxygen delignification was taken in terms of dry mass, placed in a plastic bag, and after adjusting the pulp concentration to 10% by mass using ion-exchanged water, chlorine dioxide was added so that it was 1.0% by mass based on the dry pulp mass. This was immersed in a constant temperature water bath at 70 °C for 60 minutes for D0 stage treatment. The obtained pulp was diluted to 3% by mass with ion-exchanged water and then dehydrated and washed with a Buchner funnel. The pulp after the D0 stage was placed in a plastic bag, ion-exchanged water was added to adjust the pulp concentration to 10% by mass, and then caustic soda was added so that it was 1.0% by mass and hydrogen peroxide was added so that it was 0.2% by mass based on the dry pulp mass and mixed well. Then, it was immersed in a constant temperature water bath at 70 °C for 90 minutes for E / P stage treatment. The obtained pulp was diluted to 3% by mass with ion-exchanged water and then dehydrated and washed with a Buchner funnel. The pulp after the E / P stage was put into a plastic bag, adjusted to a pulp concentration of 10% by mass using ion-exchanged water, then chlorine dioxide was added to be 0.2% by mass based on the absolute dry pulp mass, immersed in a constant temperature water bath at 70 °C for 60 minutes, and the bleaching of the D1 stage was carried out. The obtained bleached broadleaf pulp was diluted to 3% by mass with ion-exchanged water, then dehydrated and washed with a Buchner funnel. The pulp after the D1 stage was put into a plastic bag, prepared to a pulp concentration of 10% by mass using ion-exchanged water, then chlorine dioxide was added to be 1.0% by mass based on the absolute dry pulp mass, immersed in a constant temperature water bath at 70 °C for 60 minutes, and the bleaching of the D2 stage was carried out. The obtained bleached broadleaf pulp was diluted to 3% by mass with ion-exchanged water, then dehydrated and washed with a Buchner funnel to obtain a bleached broadleaf pulp slurry with a concentration of 10% by mass.

[0064] (Example 1) 60 g of the bleached softwood pulp slurry with a concentration of 10% by mass after the D2 stage was put into a plastic bag, sulfuric acid was added to adjust the pH of the pulp slurry to 3.0, then left standing at 40 °C for 12 hours for a heating treatment. The treated pulp was diluted to a concentration of about 1.0% by mass with ion-exchanged water, and then using a circular standard hand sheet machine (manufactured by Kumagai Riki Kogyo Co., Ltd.), 2 it was sheeted to a basis weight of 750 g / m

[0065] (Example 2) In Example 1, the same operations as in Example 1 were carried out except that caustic soda was added to the bleached softwood pulp slurry with a concentration of 10% by mass to adjust the pH of the pulp slurry to 5.5 to obtain a pulp sheet for fluff pulp.

[0066] (Example 3) In Example 1, the same operations as in Example 1 were carried out except that caustic soda was added to the bleached softwood pulp slurry with a concentration of 10% by mass to adjust the pH of the pulp slurry to 8.0 to obtain a pulp sheet for fluff pulp.

[0067] (Example 4) In Example 2, ion-exchanged water was added to the sun-exposed softwood pulp slurry, and the same operations as in Example 1 were performed except that the concentration of the sun-exposed softwood pulp slurry during the heating treatment was set to 2% by mass to obtain a pulp sheet for fluff pulp.

[0068] (Example 5) In Example 2, the sun-exposed softwood pulp slurry was dehydrated, and the same operations as in Example 1 were performed except that the concentration of the sun-exposed softwood pulp slurry was set to 35% by mass to obtain a pulp sheet for fluff pulp.

[0069] (Example 6) In Example 2, the same operations as in Example 1 were performed except that the heating treatment temperature of the sun-exposed softwood pulp slurry was set to 70°C to obtain a pulp sheet for fluff pulp.

[0070] (Example 7) In Example 2, the same operations as in Example 1 were performed except that the heating treatment temperature of the sun-exposed softwood pulp slurry was set to 60°C and it was allowed to cool so as to reach 25°C at the time when 12 hours had elapsed to obtain a pulp sheet for fluff pulp.

[0071] (Example 8) In Example 2, the same operations as in Example 1 were performed except that the heating treatment time of the sun-exposed softwood pulp slurry was set to 2 hours to obtain a pulp sheet for fluff pulp.

[0072] (Example 9) In Example 2, the same operations as in Example 1 were performed except that the heating treatment time of the sun-exposed softwood pulp slurry was set to 48 hours to obtain a pulp sheet for fluff pulp.

[0073] (Example 10) In [Preparation of Softwood Pulp], the same operations as in Example 2 were performed except that chips of the genus Pinus and the genus Cryptomeria were mixed at a dry mass ratio of 70:30 to obtain a pulp sheet for fluff pulp.

[0074] (Example 11) In the same manner as in Example 2, a heating treatment was performed on a sun-exposed softwood pulp slurry with a concentration of 10% by mass. Also, 60 g of a sun-exposed hardwood pulp slurry with a concentration of 10% by mass after the D2 stage was placed in a plastic bag, caustic soda was added to adjust the pH to 5.5, and then it was allowed to stand at 40°C for 12 hours to perform a heating treatment on the sun-exposed hardwood pulp. Except that the sun-exposed softwood pulp and the sun-exposed hardwood pulp that had undergone the heating treatment were mixed at a ratio of 95:5 in terms of the absolute dry mass ratio during papermaking, the same operations as in Example 1 were performed to obtain a pulp sheet for fluff pulp.

[0075] (Example 12) In Example 11, except that the sun-exposed softwood pulp and the sun-exposed hardwood pulp were mixed at a ratio of 85:15 in terms of the absolute dry mass ratio during papermaking, the same operations as in Example 11 were performed to obtain a pulp sheet for fluff pulp.

[0076] (Example 13) In Example 11, except that the sun-exposed softwood pulp and the sun-exposed hardwood pulp were mixed at a ratio of 70:30 in terms of the absolute dry mass ratio during papermaking, the same operations as in Example 11 were performed to obtain a pulp sheet for fluff pulp.

[0077] (Example 14) [Preparation of softwood pulp] and [Bleaching] in [Preparation of hardwood pulp], the pulp after the D1 stage was prepared respectively. The sun-exposed softwood pulp after the D1 stage and the sun-exposed hardwood pulp after the D1 stage were mixed at a ratio of 85:15 in terms of the absolute dry mass ratio to obtain a mixed pulp slurry of sun-exposed softwood pulp and sun-exposed hardwood pulp with a concentration of 10% by mass. Except that caustic soda was added to the mixed pulp slurry with a concentration of 10% by mass to adjust the pH of the pulp slurry to 5.5, the same operations as in Example 2 were performed.

[0078] (Comparative Example 1) In Example 1, except that the heating treatment was not performed, the same operations as in Example 1 were performed to obtain a pulp sheet for fluff pulp.

[0079] (Comparative Example 2) In Example 1, the same operations as in Example 1 were carried out except that the pH of the sun-exposed softwood pulp was adjusted to 1.0, and a pulp sheet for fluff pulp was obtained.

[0080] (Comparative Example 3) In Example 1, the same operations as in Example 1 were carried out except that the pH of the sun-exposed softwood pulp was adjusted to 10, and a pulp sheet for fluff pulp was obtained.

[0081] (Comparative Example 4) In Example 11, the same operations as in Example 11 were carried out except that the sun-exposed softwood pulp and the sun-exposed hardwood pulp were mixed at a ratio of 50:50 in terms of absolute dry mass ratio during papermaking, and a pulp sheet for fluff pulp was obtained.

[0082] (Comparative Example 5) In Example 2, the same operations as in Example 1 were carried out except that the sun-exposed softwood pulp slurry with a concentration of 10% by mass after the D2 stage was changed to a sun-exposed hardwood pulp slurry with a concentration of 10% by mass after the D2 stage.

[0083] (Measurement and Evaluation) [ISO Whiteness] The ISO whiteness of each pulp was measured according to JIS P 8148:2018.

[0084] [pH of Extract] The pH of the hot water extract of the pulp sheet for fluff pulp obtained in the examples and comparative examples was measured according to JIS P 8133-2:2013.

[0085] [Fading Property (Change in Whiteness)] Five pulp sheets for fluff pulp obtained in the examples and comparative examples were placed in a forced-air dryer set at 105°C. One sheet was taken out after 0 minutes, 15 minutes, 30 minutes, 60 minutes, and 120 minutes, respectively, and after conditioning at 23°C and 50% relative humidity for 4 hours, the ISO whiteness was measured according to JIS P 8148:2018. The fading property (change in whiteness) was calculated according to the following formula. Fading property (change in whiteness) (pt) = (B0 (%)) - B1 (%)) / B0 (%) × 100 Here, B0 represents the ISO whiteness of the pulp sheet for fluff pulp after 0 minutes, and B1 represents the ISO whiteness of the pulp sheet for fluff pulp after 120 minutes.

[0086] [Defibrillation property] The pulp sheet for fluff pulp conditioned under an environment of 23°C and 50% relative humidity was cut into 10 mm × 10 mm squares, 3 g was weighed out, and it was put into a wonder blender (manufactured by Osaka Chemical Co., Ltd., model WB-1, rotation speed 25,000 rpm) so that there was no bias, and fluff pulp was produced by defibrillating for a predetermined time. The fluff pulp was used to produce a hand-sheet with a basis weight of 25 g / m 2 using a circular standard hand sheet machine, and the time required until there was no undefibrillated material by visual observation was defined as the defibrillation time.

[0087] [Production of fluff mat] The fluff mat was produced using the fluff mat production apparatus 100 shown in Fig. 1 under an environment of 23°C and 50% relative humidity. Here, the fluff mat production apparatus 100 includes a pulp defibrator 5 (manufactured by Maruto Seiki Co., Ltd.), a stainless-steel sieve 22 with an opening size of 180 μm (manufactured by AS ONE Corporation, inner diameter 75 mm × inner height 20 mm), a stainless-steel sieve 24 with an opening size of 150 μm (manufactured by AS ONE Corporation, inner diameter 75 mm × inner height 20 mm), a column 20 made of a PET resin plate cut to 70 cm × 40 cm (manufactured by Acrysandee Co., Ltd., Sunday PET, thickness 0.5 mm), a polypropylene powder funnel 10 (manufactured by AS ONE Corporation, model number No. 166, diameter 180 mm, outer diameter of the feet 43 mm, length of the feet 48 mm), a polypropylene powder funnel 30 (manufactured by AS ONE Corporation, model number No. 169, diameter 120 mm, outer diameter of the feet 30 mm, length of the feet 27 mm), and a household vacuum cleaner 40 (manufactured by Hitachi Home & Life Solutions, Inc., model number CV-CF4), which was assembled into the configuration shown in Fig. 1. First, the total weight of the stainless-steel sieve with an opening size of 180 μm and the column was measured in advance. Next, the pulp defibrator and the household vacuum cleaner were started. The suction force of the household vacuum cleaner was set to weak (suction work rate of about 80 W), and the fluff pulp without undefibrated matter obtained during the evaluation of [defibratability] was fed little by little from the top of the fluff mat production apparatus. Occasionally, the weight of the fluff mat formed on the stainless-steel sieve with an opening size of 180 μm was measured, and the fluff mat was formed until it reached 200 g / m 2 After reaching 200 g / m 2 After reaching, the pulp defibrator and the household vacuum cleaner were stopped. After removing the column, the surface of the fluff mat was gently pressed with a circular stainless-steel plate to shape it, and the fluff mat (diameter 75 mm) was gently taken out from the sieve with an opening size of 180 μm so that its shape would not collapse. The surface that had touched the stainless-steel mesh was defined as the wire surface of the fluff mat.

[0088] [Measurement of the reverse return rate of the fluff mat] The measurement of the reverse return rate of the fluff mat was carried out under an environment of 23°C and 50% relative humidity. For the 200 g / m fluff mat produced 2The fluff mat was placed on a 5-mm-thick acrylic plate with the wire side facing up. After sandwiching a 2-mm-thick spacer, another 5-mm-thick acrylic plate was placed on top and pressed for 10 minutes using a tabletop press. After pressing, the acrylic plate placed on top was removed and left to stand for 30 minutes. A stainless-steel base plate (5 mm thick, 11×11 cm) was placed on a horizontal experimental table, and one fluff mat was placed on it with the wire side facing up. SAP (manufactured by Sumitomo Seika Chemicals Co., Ltd., SA60SXII) was evenly sprinkled so that SAP / fluff mat = 0.35, and another fluff mat was placed on it with the wire side facing up (the total basis weight of the fluff mats was 400 g / m 2 ). On top of that, a 11-cm×11-cm square core wrap tissue (manufactured by Oji Napier Co., Ltd., basis weight 16 g / m 2 ) was placed with the paper flow direction in the vertical direction. On top of that, a strike-through plate (10 cm×10 cm, thickness 85 mm, weight 665 g) made of stainless steel with a 25-mm-diameter hole in the center was placed, and after 10 seconds, 20 g of artificial urine was poured into the hole of the strike-through plate. After the artificial urine was completely absorbed, the strike-through plate was immediately removed. Next, an 11-cm×11-cm square polyethylene sheet was placed on top of the core wrap tissue, and on top of that, an 11-cm×11-cm square chloroprene rubber sponge rubber sheet (manufactured by AS ONE Corporation, thickness 10 mm, hardness (Asker C hardness meter): 45 degrees) was placed, and on top of that, an 11-cm×11-cm square 5-mm-thick acrylic plate was placed, and on top of that, a 2.2-kg weight was placed. The total weight of the polyethylene sheet, sponge rubber sheet, two acrylic plates, and 2.2-kg weight was 2.31 kg, and the area of the fluff mat was 0.00442 m 2Therefore, the pressure applied to the fluff mat was 5.1 kPa. Pressurization was carried out at 5.1 kPa for 3 minutes. Next, two polyethylene sheets, a sponge rubber sheet, two acrylic plates, and 2.2 kg of copper were removed. Ten 11 cm × 11 cm square filter papers (manufactured by ADVANTEC Co., Ltd., No. 1640) that had been conditioned in an environment of 23°C and 50% relative humidity and had a known weight were placed such that the front surface was in contact with the paper diaper core wrap tissue. Again, a clear file, a urethane rubber sheet, two acrylic plates, and 2.2 kg of copper were placed, and artificial urine was absorbed by the filter papers while pressurizing for 2 minutes. After 2 minutes, the ten filter papers were taken out and weighed, and the reverse return rate was measured using the following calculation formula. The artificial urine used here was prepared by the following procedure. First, methylene blue (manufactured by Kanto Chemical Co., Inc.) was dissolved in ion-exchanged water to prepare a 0.50 mass% methylene blue aqueous solution. Next, 19.40 g of urea (manufactured by Kanto Chemical Co., Inc.), 8.040 g of sodium chloride (manufactured by Kanto Chemical Co., Inc.), 2.045 g of magnesium sulfate heptahydrate (manufactured by Kanto Chemical Co., Inc.), and 0.835 g of calcium chloride dihydrate were successively weighed into a 500 ml beaker. After adding an appropriate amount of ion-exchanged water, 1.50 g of the 0.50 mass% methylene blue aqueous solution was added dropwise. Then, the solution was transferred to a 1 L volumetric flask and made up to 1 L to obtain artificial urine.

[0089]

Number

[0090] [pH when fluff pulp and artificial urine are mixed] The pulp sheet for fluff pulp conditioned at 23°C and 50% relative humidity was cut into 10 mm x 10 mm squares, 3 g was weighed and put into a wonder blender (manufactured by Osaka Chemical Co., Ltd., model WB-1, rotation speed 25,000 rpm) so that there was no bias, and defibrinated for 20 seconds to produce fluff pulp. 5 g of the fluff pulp produced by the above method was taken, spread thinly on aluminum foil, and 20 g of artificial urine used in [Measurement of reverse return rate of fluff mat] was sprinkled using a pipette. Then, the fluff pulp was put into a plastic bag with a chuck and left in an oven at 40°C for 1 hour. After 1 hour, the fluff pulp was wrung by hand and the pH of the wrung liquid was measured.

[0091] [Sensory evaluation (rash)] Using the fluff mats formed from the pulp sheets for fluff pulp of the examples and comparative examples, disposable diapers were produced with reference to the description of Patent No. 5849759. The disposable diapers were worn by 20 monitors, and the presence or absence of rash was evaluated. The evaluation criteria were as follows. A: The number of people with rash is 0 B: The number of people with rash is 1 - 2 C: The number of people with rash is 3 - 4 D: The number of people with rash is 5 or more

[0092]

Table 1

[0093]

Table 2

[0094] Compared with the comparative examples, in the examples, a fluff mat capable of suppressing the occurrence of skin rash was obtained.

Explanation of symbols

[0095] 5 Pulp defibrinator 10 Polypropylene powder funnel 20 Column 22, 24 Stainless steel sieve 30 Polypropylene powder funnel 40 Vacuum cleaner (suction cleaner) Stainless steel sieve with 22 meshes and 180 μm opening 100 Fluff mat manufacturing device

Claims

1. A pulp sheet for fluff pulp, wherein the pH of the hot water extract measured in accordance with JIS P 8133-2:2013 is 7.0 to 9.

5.

2. The pulp sheet for fluff pulp according to Claim 1, wherein the ISO whiteness measured in accordance with JIS P 8148:2018 is 80% or more.

3. The pulp sheet for fluff pulp contains softwood pulp, The pulp sheet for fluff pulp according to Claim 1, wherein the content of hardwood pulp relative to all pulp components in the pulp sheet for fluff pulp is 30% by mass or less.

4. The pulp sheet for fluff pulp contains softwood pulp, The pulp sheet for fluff pulp according to Claim 1, wherein the content of hardwood pulp relative to all pulp components in the pulp sheet for fluff pulp is 15% by mass or less.

5. A fluff mat formed from the pulp sheet for fluff pulp according to any one of Claims 1 to 4.

6. The fluff mat according to Claim 5, wherein 20 parts by mass of artificial urine containing 1.94% by mass of urea, 0.8040% by mass of sodium chloride, 0.2045% by mass of magnesium sulfate heptahydrate, and 0.0835% by mass of calcium chloride dihydrate is added to 5 parts by mass of the fluff mat, and the pH of the squeezed liquid of the fluff mat after standing at 40°C for 1 hour in a sealed state is 6.6 or more.

7. An absorbent article comprising the fluff mat according to Claim 5.

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