Absorbent sheet

Abstract

An absorbent sheet according to one embodiment comprises a body part that has a water-permeable front surface sheet, a back surface sheet that is on the reverse side from the front surface sheet, and an absorption body that is between the front surface sheet and the back surface sheet. The absorption body has an absorbent core that includes thermoplastic resin fibers. The thermoplastic resin fiber fraction of the entire absorbent core is at least 30% by weight ratio. When a load of 3.0 kg has been applied for 10 minutes from the thickness direction to the body part as folded along a folding line that crosses the absorbent core and divides the body part into a first portion and a second portion and then the first portion is lifted perpendicularly, the second portion naturally separates from the first portion, and the angle formed between the first portion and the second portion is at least 145°.

Description

absorbent sheet

[0001] The present disclosure relates to absorbent sheets.

[0002] Absorbent sheets for absorbing liquids are widely used. For example, Patent Document 1 listed below describes a pet urine absorbent sheet that includes a water-permeable top sheet, a water-impermeable back sheet, and an absorbent body disposed between the top sheet and the back sheet, with the edges of the top sheet and the back sheet joined together.

[0003] Japanese Patent Application Laid-Open No. 2003-92940

[0004] Generally, absorbent sheets are sold in a folded and compressed state, compactly contained in a package. To increase compactness, it is desirable to compress the absorbent sheet strongly, but strongly compressing a folded absorbent sheet may cause creases in the absorbent sheet. If the absorbent sheet has creases, it will not be possible to deform the absorbent sheet into a desired shape according to the intended use when it is removed from the package, which may cause problems in using the absorbent sheet.

[0005] Therefore, an object of the present disclosure is to provide an absorbent sheet that is less likely to develop creases.

[0006] An absorbent sheet according to one embodiment comprises a main body portion having a water-permeable top sheet, a back sheet opposite the top sheet, and an absorbent body arranged between the top sheet and the back sheet, wherein the absorbent body has an absorbent core containing thermoplastic resin fibers, and the proportion of thermoplastic resin fibers in the entire absorbent core is 30% or more by weight, and when a load of 3.0 kg is applied in the thickness direction to the main body portion folded along a fold line that crosses the absorbent core and divides the main body portion into a first part and a second part for 10 minutes, and then the first part is lifted vertically, the second part naturally separates from the first part, and the angle between the first part and the second part is 145° or more.

[0007] When an absorbent core containing pulp is folded, the cellulose fibers, the main component of pulp, form hydrogen bonds and bind to each other, forming creases. In contrast, in this embodiment, the absorbent core contains 30% or more thermoplastic resin fibers by weight. Unlike pulp, thermoplastic resin fibers do not contain hydroxyl groups and do not form hydrogen bonds, so when the absorbent sheet is folded along the fold lines and compressed, the absorbent sheet is less likely to form creases. Therefore, when the folded absorbent sheet is removed from the package, the absorbent sheet is prevented from maintaining its folded shape and is naturally unfolded. As a result, the absorbent sheet can be formed into a desired shape depending on its intended use.

[0008] The fold line may be a fold line for folding the main body in half so that the back sheet is disposed inside. In this case, the absorbent sheet stored in half can be naturally unfolded when removed from the package.

[0009] The proportion of thermoplastic resin fibers in the entire absorbent core may be 65% or more by weight. By making the proportion of thermoplastic resin fibers 65% or more, the formation of creases in the absorbent sheet can be more effectively suppressed. As a result, the absorbent sheet can be easily unfolded when removed from the package.

[0010] The average fiber length of the thermoplastic resin fibers may be from 0.2 mm to 8.0 mm. By setting the average fiber length of the thermoplastic resin fibers within this range, it is possible to prevent creases from forming in the absorbent sheet.

[0011] The absorbent body further includes a core wrap covering the absorbent core, and the average fiber length of the thermoplastic resin fibers may be shorter than the average fiber length of the core wrap. The average fiber length of the core wrap may be 100 mm or more. By making the average fiber length of the core wrap relatively long, the absorbent core can be stably held.

[0012] The core wrap includes a first core wrap sheet disposed between the top sheet and the absorbent core, and a second core wrap sheet disposed between the back sheet and the absorbent core, and at least one of the first core wrap sheet and the second core wrap sheet may contain synthetic fibers. By including at least one of the first core wrap sheet and the second core wrap sheet in synthetic fibers, the formation of creases in the core wrap can be suppressed.

[0013] Both the first core wrap sheet and the second core wrap sheet may contain synthetic fibers, which can prevent creases from forming in the core wrap.

[0014] The first core wrap sheet may be made of tissue, and the second core wrap sheet may be made of nonwoven fabric. When the main body is folded so that the back sheet is positioned inside, the fold angle of the second core wrap sheet becomes small, making it easier for creases to form in the second core wrap sheet. By making the second core wrap sheet of nonwoven fabric, it is possible to prevent creases from forming in the core wrap. The nonwoven fabric may be an SMS nonwoven fabric.

[0015] The ratio of the thickness of the main body portion folded along the fold lines to the thickness before pressure is applied may be 94% or more when a load of 3.0 kg is applied to the main body portion folded along the fold lines in the thickness direction for 10 minutes and the load is released 3 minutes later. With this absorbent sheet, the thickness of the absorbent sheet recovers in a short time after the load is released, thereby suppressing a decrease in the water absorption performance of the absorbent sheet.

[0016] The basis weight of the thermoplastic resin fibers in the fold line region of the absorbent core may be smaller than the basis weight of the thermoplastic resin fibers in the region other than the fold line region of the absorbent core. The absorbent core may contain thermoplastic resin fibers in the fold line region. By containing the thermoplastic resin fibers in the fold line region, a restoring force acts on the main body portion folded along the fold line, allowing the absorbent sheet to naturally unfold.

[0017] The bending rigidity of the main body by the KES method is 0.20 [gf cm 2 If the bending rigidity of the main body is high, the folded portion may be stiff, which may cause discomfort to the pet. 2 / cm] or less, it is possible to suppress the discomfort felt by the pet.

[0018] The thermoplastic resin fibers may be made of an olefin resin or a PET resin. When the thermoplastic resin fibers are made of an olefin resin or a PET resin, creases are less likely to form in the absorbent sheet even when the absorbent sheet is folded along the fold lines and compressed.

[0019] The backsheet has an inner surface facing the absorbent body and an outer surface opposite the outer surface, and the outer surface of the backsheet is provided with an engagement portion that engages with a pet waste disposal sheet that absorbs pet waste, and the engagement portion may be positioned off the fold line, which prevents creases from forming in the engagement portion.

[0020] The area of ​​the main body in plan view is 400 cm ２ By making the area of ​​the main body portion significantly smaller than that of a typical excrement disposal sheet, the absorbent sheet can be used by overlapping part of the excrement disposal sheet.

[0021] Another aspect of the absorbent sheet comprises a main body portion having a water-permeable top sheet, a back sheet opposite the top sheet, and an absorbent body arranged between the top sheet and the back sheet, the absorbent body having an absorbent core containing thermoplastic resin fibers made of olefin resin or PET resin, the main body portion having a fold line that crosses the absorbent core, the back sheet having an inner surface facing the absorbent body and an outer surface opposite the top surface, the outer surface of the back sheet having an engagement portion that engages with an excrement disposal sheet that absorbs pet excrement, the engagement portion being arranged in a position offset from the fold line.

[0022] In this aspect, the absorbent core contains thermoplastic resin fibers made of an olefin resin or a PET resin that do not form hydrogen bonds, so that when the absorbent sheet is folded along the fold lines and compressed, creases are less likely to form in the absorbent sheet. Furthermore, if the engagement portions are located on the fold lines, there is a risk that creases will form in the engagement portions when the absorbent sheet is folded along the fold lines. In contrast, in this aspect, the engagement portions are located at positions offset from the fold lines, so that when the absorbent sheet is folded along the fold lines, the engagement portions are prevented from bending, and as a result, the formation of creases in the absorbent sheet is suppressed.

[0023] The proportion of the thermoplastic resin fibers in the entire absorbent core may be 30% or more by weight. By making the proportion of the thermoplastic resin fibers 30% or more, it is possible to more effectively prevent the absorbent sheet from forming creases.

[0024] The absorbent sheet is used by overlapping a portion of the excrement disposal sheet that absorbs animal excrement, and may have an area smaller than the area of ​​the excrement disposal sheet, in which case the absorbent sheet can be used by overlapping the excrement disposal sheet, for example, to cover urine stains on the excrement disposal sheet.

[0025] The thermoplastic resin fibers may be derived from pulverized nonwoven fabric, in which case the absorbent core can be manufactured using nonwoven fabric offcuts or the like as materials.

[0026] According to various aspects of the present invention, it is possible to prevent the absorbent sheet from forming creases.

[0027] 4 is a diagram showing an example of use of a pet sheet according to one embodiment. FIG. 5 is a schematic side view showing a pet sheet placed on a disposal sheet. FIG. 6 is a plan view of the pet sheet as seen from the front side. FIG. 7 is a plan view of the pet sheet as seen from the back side. FIG. 8 is a schematic cross-sectional view of the pet sheet taken along line V-V in FIG. 3. FIG. 9 is a plan view showing the pet sheet in a folded state. FIG. 10 is a schematic cross-sectional view of a package. FIG. 11 is a side view showing a pet sheet transitioning from a folded state to an unfolded state. FIG. 12 is a diagram showing the relationship between the proportion of thermoplastic resin fibers and the angle θ. FIG. 13 is a diagram showing the relationship between the proportion of thermoplastic resin fibers and the bending rigidity of the pet sheet. FIG. 14 is a diagram showing the relationship between the proportion of thermoplastic resin fibers and the compression recovery rate of the pet sheet.

[0028] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the description of the drawings, the same elements are designated by the same reference numerals, and duplicate explanations will be omitted. The drawings may be partially simplified or exaggerated for ease of understanding, and the dimensional ratios are not limited to those shown in the drawings.

[0029] A pet sheet 1 according to one embodiment will be described with reference to Figures 1 to 5. The pet sheet 1 is an example of an absorbent sheet that absorbs pet excrement. First, an example of how the pet sheet 1 can be used will be described with reference to Figure 1. Figure 1(A) shows a pet excrement disposal sheet (hereinafter referred to as "disposal sheet") 100. Typically, the disposal sheet 100 has a rectangular planar shape and includes a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorbent disposed between the top sheet and the back sheet.

[0030] The disposal sheet 100 is placed in a pet's living space (e.g., indoors) and is used to absorb and retain pet excrement to keep the space clean. That is, the disposal sheet 100 provides a space for pet excretion. The disposal sheet 100 may be placed directly on the floor or ground of the pet's living space, or may be placed on a tray.

[0031] In this specification, pets broadly encompass vertebrates and invertebrates, and typically include pet animals such as dogs, cats, rabbits, and hamsters. Pets also include animals other than mammals, such as birds, reptiles, and amphibians. Pet waste U typically includes urine, but also includes low-viscosity feces, saliva, blood, and other body fluids that can be absorbed by an absorbent. In the following explanation, an example will be described in which urine is absorbed as the waste U.

[0032] Pets tend to avoid excretion marks (urine marks) on the disposal sheet 100 when urinating. As a result, pets may urinate in an awkward position to avoid the urine marks, resulting in urination outside the disposal sheet 100 and soiling the pet's habitat. To avoid this problem, users of the disposal sheet 100 (e.g., pet owners) may replace the disposal sheet 100 with a new one even though there is usable area (area that can absorb new urine). However, replacing a usable disposal sheet 100 is not appropriate not only from an economic standpoint but also from an environmental protection standpoint.

[0033] To solve the above problem, the pet sheet 1 is used by overlapping the area of ​​the disposal sheet 100 where excrement U has been absorbed (e.g., urine stains), as shown in Figure 1(B). By placing the disposal sheet 100 over the urine stains, the urine stains can be visually concealed, preventing pets from avoiding the urine stains and urinating outside the disposal sheet 100. As a result, the disposal sheet 100 can be used repeatedly for a long period of time, which is an improvement in terms of economy and environmental protection.

[0034] On the other hand, the pet sheet 1 is sometimes sold in a folded and compressed state, compactly housed in a package. To increase compactness, it is desirable to strongly compress the pet sheet 1 before packaging, but strongly compressing the folded pet sheet 1 may cause creases in the pet sheet 1. The creases are linear wrinkles formed along the fold line L1 of the pet sheet 1.

[0035] If the pet sheet 1 is creased, it will not be possible to deform the absorbent sheet into the desired shape for its intended use when it is removed from the package. Specifically, as shown in Figure 2, if the pet sheet 1 is creased, the pet sheet 1 will not unfold naturally and will be placed on the disposal sheet 100 in a bent, mountain-shaped state. In this case, the area on the disposal sheet 100 where the pet sheet 1 is placed will appear locally raised, which will cause discomfort to the pet and may make the pet reluctant to use the disposal sheet 100.

[0036] To solve this problem, the pet sheet 1 is designed to be less likely to crease and to unfold naturally when removed from the package. The natural unfolding of the pet sheet 1 reduces the effort required for the user to unfold the pet sheet 1, and also reduces the discomfort felt by the pet because the pet sheet 1 lies flat on the disposal sheet 100. The structure of the pet sheet 1 will be described in detail below.

[0037] Fig. 3 is a plan view of an exemplary pet sheet 1 as viewed from the top sheet 2 side. Fig. 4 is a plan view of the pet sheet 1 as viewed from the back sheet 3 side. Fig. 5 is a schematic cross-sectional view of the pet sheet 1 taken along line IV-IV in Fig. 3. In the following description, the thickness direction of the pet sheet 1 is referred to as the Z direction, and the two directions perpendicular to each other as viewed from the Z direction are referred to as the X direction and the Y direction, respectively. The Y direction is parallel to the fold line L1 of the pet sheet 1, which will be described later.

[0038] As shown in Figures 3 and 4, the pet sheet 1 has a main body 10 having a rectangular planar shape. The planar shape of the main body 10 is not limited to a rectangular shape, and any shape such as a polygon, circle, or ellipse can be adopted. The size of the main body 10 is determined depending on the size or type of pet that will use the pet sheet 1. Typically, the area of ​​the pet sheet 1 in a planar view is smaller than the area of ​​the disposal sheet 100, for example, 400 cm ２ The following is the result.

[0039] The main body 10 includes a water-permeable top sheet 2, a back sheet 3 on the opposite side of the top sheet, and an absorbent 4 disposed between the top sheet 2 and the back sheet 3. The top sheet 2 provides a surface 2a that faces the pet (upward) during use. Typically, the top sheet 2 is made of a water-permeable nonwoven fabric, which transfers urine excreted by the pet to the absorbent 4. Examples of nonwoven fabrics that make up the top sheet 2 include air-through nonwoven fabrics, spunbond nonwoven fabrics, and point-bond nonwoven fabrics. The top sheet 2 may be hydrophilized with a surfactant. To ensure visual integrity, the top sheet 2 of the pet sheet 1 may be made of a nonwoven fabric of a similar color to the top sheet of the treatment sheet 100. This prevents the pet from feeling uncomfortable using the pet sheet 1.

[0040] The backsheet 3 is disposed on the opposite side of the topsheet 2 in the Z direction and is water-impermeable. The backsheet 3 has substantially the same dimensions as the topsheet 2 and is disposed so as to completely overlap the topsheet 2 when viewed in the Z direction. The backsheet 3 provides a back surface (outer surface) 3a that is placed on the treatment sheet 100 during use. Typically, the backsheet 3 is made of a water-impermeable resin film. Examples of the resin film that constitutes the backsheet 3 include polyethylene film and polypropylene film. The backsheet 3 may be made of a water-repellent or hydrophobic nonwoven fabric, or may be a laminate formed by bonding a resin film and a nonwoven fabric.

[0041] The back sheet 3 prevents urine excreted on the pet sheet 1 from migrating toward the disposal sheet 100. The back sheet 3 may be water permeable. This is because the disposal sheet 100 has the function of absorbing urine, so there is no major problem even if urine excreted on the pet sheet 1 moves toward the disposal sheet 100.

[0042] The absorbent body 4 is disposed between the topsheet 2 and the backsheet 3 and absorbs the pet's urine. The absorbent body 4 has a substantially rectangular planar shape. As shown in FIG. 3 , the absorbent body 4 is slightly smaller than the topsheet 2 and the backsheet 3 and is disposed in the center of the main body portion 10. As a result, the main body portion 10 is formed with an absorbent section 13 in which the absorbent body 4 is disposed between the topsheet 2 and the backsheet 3, and a flap section 14 in which the absorbent body 4 is not disposed between the topsheet 2 and the backsheet 3. Typically, the flap section 14 is a rectangular frame-shaped region in which the topsheet 2 and the backsheet 3 are bonded together without the absorbent body 4 interposed therebetween, and is formed to surround the absorbent section 13. In other words, the flap section 14 is formed along the outer edge of the pet pad 1.

[0043] The rigidity of the flap portion 14 is lower than that of the absorbent portion 13 due to the absence of the absorber 4. In other words, the flap portion 14 is thin and soft, making it easy to grip with your hands. The pet sheet 1 folded in half can be naturally unfolded by gripping and lifting the flap portion 14.

[0044] As shown in Figure 5, the absorbent body 4 includes an absorbent core 41 and a core wrap 42. The absorbent core 41 includes thermoplastic resin fibers made of a thermoplastic resin. The thermoplastic resin fibers are synthetic fibers made of an olefin resin such as polyethylene (PE) or polypropylene (PP), or polyethylene terephthalate resin (PET). These thermoplastic resin fibers do not contain hydroxyl groups and therefore do not form hydrogen bonds, which can cause creases.

[0045] Thermoplastic resin fibers can be produced by pulverizing synthetic resin nonwoven fabric using a pulverizer. Thermoplastic resin fibers can also be produced from nonwoven fabric scraps generated during the production of pet wipes 1, disposal sheets 100, or other products. Nonwoven fabrics typically have fiber lengths of approximately 30 mm to 51 mm. Because the thermoplastic resin fibers contained in the absorbent core 41 are produced by pulverizing nonwoven fabric, the fiber lengths of the thermoplastic resin fibers are shorter than those of typical nonwoven fabrics. The average fiber length of the thermoplastic resin fibers contained in the absorbent core 41 is, for example, 0.2 mm or more and 8.0 mm or less. The average fiber length of the thermoplastic resin fibers may also be, for example, 0.2 mm or more and 0.35 mm or less. The thermoplastic resin fibers function to absorb and diffuse pet urine into the absorbent core 41 by capillary action.

[0046] The absorbent body 4 further contains a superabsorbent polymer (SAP). Examples of the superabsorbent polymer include particulate or fibrous polymers such as polyacrylic acid, starch, and cellulose. The superabsorbent polymer is held within the absorbent core 41 by the thermoplastic resin fibers becoming entangled with the superabsorbent polymer.

[0047] The proportion of thermoplastic resin fibers in the entire absorbent core 41 is 30% or more, 40% or more, 50% or more, 60% or more, or 65% or more by weight. That is, the proportion of superabsorbent polymer in the entire absorbent core 41 is 70% or less by weight. Increasing the proportion of thermoplastic resin fibers improves urine diffusibility and shape retention of the absorbent core 41. On the other hand, increasing the weight ratio of superabsorbent polymer improves the water retention performance of the absorbent core 41. From the viewpoint of improving the shape retention of the absorbent core 41, the weight ratio of thermoplastic resin fibers may be higher than the weight ratio of superabsorbent polymer.

[0048] The absorbent core 41 may further contain pulp. For example, cellulose pulp, which is primarily composed of cellulose fibers, is used as the pulp. However, because cellulose fibers have hydroxyl groups, the cellulose fibers form hydrogen bonds and bind to each other, making the absorbent core 41 more susceptible to creases. Therefore, from the perspective of suppressing crease formation, it is preferable that the proportion of pulp in the entire absorbent core 41 be 50% or less by weight, which is lower than the proportion of thermoplastic resin fibers. The absorbent core 41 may be composed of thermoplastic resin fibers and a superabsorbent polymer without containing pulp.

[0049] The core wrap 42 is made of, for example, tissue or a nonwoven fabric sheet, and covers the upper surface 41a, side surfaces 41b, and lower surface 41c of the absorbent core 41. The core wrap 42 is adhered to the surface of the absorbent core 41 with, for example, a hot melt adhesive. The core wrap 42 may include a first core wrap sheet 42a and a second core wrap sheet 42b. The first core wrap sheet 42a is disposed between the topsheet 2 and the absorbent core 41 and covers the upper surface 41a and side surfaces 41b of the absorbent core 41. The second core wrap sheet 42b is disposed between the backsheet 3 and the absorbent core 41 and covers the lower surface 41c of the absorbent core 41.

[0050] In one embodiment, at least one of the first core wrap sheet 42a and the second core wrap sheet 42b contains synthetic fibers that do not have hydroxy groups. For example, the first core wrap sheet 42a is made of tissue, and the second core wrap sheet 42b is made of nonwoven fabric. While tissue improves urine diffusion, it is made of cellulose pulp and therefore prone to creases. On the other hand, nonwoven fabric is made of synthetic fibers that do not form hydrogen bonds and therefore is less prone to creases. For example, the nonwoven fabric that makes up the second core wrap sheet 42b is an SMS nonwoven fabric, which is made by sequentially layering spunbond, meltblown, and spunbond.

[0051] When the main body 10 is folded so that the back sheet 3 is disposed on the inside, the folding angle of the second core wrap sheet 42b, which is disposed on the inside of the folding direction relative to the first core wrap sheet 42a, becomes smaller, making it easier for creases to form in the second core wrap sheet 42b. Here, by forming the second core wrap sheet 42b from a nonwoven fabric, the formation of creases in the second core wrap sheet 42b is suppressed.

[0052] When the main body portion 10 is folded so that the topsheet 2 is positioned on the inside, the first core wrap sheet 42a may be made of nonwoven fabric, and the second core wrap sheet 42b may be made of tissue. The average fiber length of the nonwoven fabric making up the first core wrap sheet 42a is 100 mm or more. That is, the average fiber length of the thermoplastic resin fibers contained in the absorbent core 41 is shorter than the average fiber length of the nonwoven fabric making up the core wrap 42. By using a nonwoven fabric with a relatively long fiber length for the core wrap 42, leakage of the superabsorbent polymer from the absorbent core 41 is suppressed. Note that both the first core wrap sheet 42a and the second core wrap sheet 42b may be made of tissue. The average fiber length of the thermoplastic resin fibers contained in the absorbent core 41 may be shorter than the average fiber length of the tissue making up the core wrap 42.

[0053] Furthermore, both the first core wrap sheet 42a and the second core wrap sheet 42b may be made of nonwoven fabric, which can effectively prevent creases from forming in the core wrap 42.

[0054] As shown in Figures 4 and 5, the back surface 3a of the backsheet 3 is provided with an engaging portion 7 having a bonding surface 7a that can be bonded to the disposal sheet 100. For example, the engaging portion 7 is a hook-and-loop fastener that engages with the front surface of the disposal sheet 100. The engaging portion 7 may also be an adhesive surface with release paper. In the embodiment shown in Figure 4, four rectangular engaging portions 7 are provided at the corners (four corners) of the back surface 3a. These four engaging portions 7 are arranged so that the outer edge of each engaging portion 7 is spaced from the outer edge of the back surface 3a. However, each engaging portion 7 may also be arranged so that the outer edge of each engaging portion 7 coincides with the outer edge of the back surface 3a. The engaging portions 7 are provided with their bonding surfaces 7a exposed to the outside.

[0055] When the engaging portion 7 is a hook-and-loop fastener, the connecting surface 7a has a plurality of hooks protruding from the hook sheet. When the pet sheet 1 is placed on the disposal sheet 100, the hooks on the connecting surface 7a become entangled with the nonwoven fabric that constitutes the top sheet of the disposal sheet 100, thereby connecting the pet sheet 1 to the disposal sheet 100. Meanwhile, the shape of the hooks is designed so that the connecting surfaces 7a of the engaging portion 7 do not connect to each other.

[0056] The pet sheet 1 is stored folded in half along a fold line L1 extending in the Y direction. As shown in Fig. 3, the fold line L1 extends in the Y direction so as to cross the absorbent core 41 along the center line of the main body portion 10 in the X direction. In other words, the fold line L1 is a fold line for folding the pet sheet 1 in half. This fold line L1 divides the main body portion 10 into a first portion 11 located on one side of the fold line L1 (the left side in Fig. 3) and a second portion 12 located on the other side of the fold line L1 (the right side in Fig. 3).

[0057] When viewed from the thickness direction Z, the fold line L1 crosses the absorbent core 41 of the absorbent body 4. The absorbent core 41 also contains thermoplastic resin fibers in the region above the fold line L1. This applies a restoring force to the folded main body 10, making it easier for the pet sheet 1 to unfold. On the other hand, when the pet sheet 1 is folded along the fold line L1, the thermoplastic resin fibers are biased, and the basis weight of the thermoplastic resin fibers in the region above the fold line L1 of the absorbent core 41 may be smaller than the basis weight of the thermoplastic resin fibers in regions other than the region above the fold line L1 of the absorbent core 41.

[0058] As shown in FIG. 3 , the engaging portions 7 are positioned offset from the fold line L1 (not overlapping the fold line L1). More specifically, the four engaging portions 7 are positioned symmetrically with respect to the fold line L1. FIG. 6 shows the pet sheet 1 folded in half along the fold line L1 so that the back surface 3a is positioned on the inside. As described above, the four engaging portions 7 are positioned symmetrically with respect to the fold line L1. Therefore, when the pet sheet 1 is folded in half along the fold line L1, the two engaging portions 7 on the first portion 11 contact the two engaging portions 7 on the second portion 12. Here, the engaging portions 7 are designed so that the connecting surfaces 7a do not connect to each other. Therefore, when the pet sheet 1 is folded in half, the first portion 11 and the second portion 12 are not connected to each other and naturally separate from each other.

[0059] 7 is a schematic cross-sectional view showing a package 50 containing multiple pet sheets 1. The package 50 is, for example, a bag having a substantially rectangular parallelepiped shape, and is made of a synthetic resin such as polyethylene, polypropylene, or polyethylene terephthalate. A tear line (not shown) is formed in the package 50, and opening the package 50 along the tear line forms an opening for removing the pet sheets 1 contained in the package 50.

[0060] As shown in FIG. 7 , the pet sheet 1 is folded in half along the fold line L1 so that the back surface 3a is positioned inside, and is then placed in a compressed state within the packaging 50. To use the pet sheet 1, the user inserts their fingers into the packaging 50 through the opening, pinches and pulls the flap portion 14 of the first portion 11 or the second portion 12 of the pet sheet 1, and removes the pet sheet 1 from the packaging 50. The pet sheet 1 is then placed on top of the disposal sheet 100 with the back surface 3a facing the disposal sheet 100. If the pet sheet 1 has a crease along the fold line L1, the pet sheet 1 will not unfold naturally, as shown in FIG. 2 , but will instead be placed on top of the disposal sheet 100 in a mountain-shaped bent state. In this case, the area where the pet sheet 1 is placed will appear locally raised on the disposal sheet 100, causing discomfort to the pet.

[0061] Therefore, the pet sheet 1 is designed so that when the first portion 11 is lifted vertically, the second portion 12 naturally separates from the first portion 11, making the angle θ (see FIG. 2 ) between the first portion 11 and the second portion 12 145° or greater. In the following description, the state in which the pet sheet 1 is folded along the fold line L1 is referred to as the "folded state," and the state in which the first portion 11 and the second portion 12 are separated is referred to as the "unfolded state." Furthermore, the function of the pet sheet 1, in which the angle θ between the first portion 11 and the second portion 12 is 145° or greater when the first portion 11 of the pet sheet 1 compressed under specified conditions is lifted vertically, is referred to as the "unfolded function."

[0062] Whether or not the pet sheet 1 has the above-mentioned unfolding function is confirmed by the unfolding function test shown below. In the unfolding function test, first, three pet sheets 1 folded in half are placed on a horizontal table in a constant temperature and humidity environment (room temperature 20°C, humidity 60%). Next, a load of 3.0 kg (5.3 x 10 ３ [N / m ２]) is applied for 10 minutes. After that, the load on the pet sheet 1 is released, and the first portion 11 of the pet sheet 1 is lifted vertically as shown in Fig. 8(A). When the first portion 11 is lifted vertically, the second portion 12 naturally separates from the first portion 11 as shown in Fig. 8(B), and the pet sheet 1 is in an unfolded state.

[0063] Next, the angle θ between the first portion 11 and the second portion 12 is measured. The angle θ is measured for each of the three pet sheets 1, and the average value of the angle θ is calculated. If the average value of the angle θ is 145° or greater, the pet sheet 1 is determined to have an unfolding function.

[0064] The angle θ depends on the proportion of thermoplastic resin fibers in the entire absorbent core 41, and the higher the proportion of thermoplastic resin fibers, the higher the angle θ tends to be. This is because a high proportion of thermoplastic resin fibers suppresses the formation of creases and makes it easier to unfold the pet sheet 1. As described above, the pet sheet 1 has an unfolding function, with the proportion of thermoplastic resin fibers in the entire absorbent core 41 set to 30% or more by weight.

[0065] The pet sheet 1 also has a high compression recovery rate. The compression recovery rate refers to the ratio of the thickness of the pet sheet 1 in a folded state before compression to the thickness of the pet sheet 1 in a folded state after compression. The compression recovery rate depends on the proportion of thermoplastic resin fibers in the entire absorbent core 41, and tends to be higher as the proportion of thermoplastic resin fibers increases. Specifically, the ratio of the thickness of the main body 10 of the pet sheet 1 in a folded state to the thickness of the main body 10 of the pet sheet 1 in a folded state before compression, three minutes after applying a load of 3.0 kg in the thickness direction to the main body 10 of the pet sheet 1 in a folded state and releasing the load, may be 94% or more. A high compression recovery rate of 94% or more allows the thickness of the compressed pet sheet 1 to recover in a short time, thereby suppressing a decrease in the water absorption performance of the pet sheet 1. By making the proportion of thermoplastic resin fibers in the entire absorbent core 41 30% or more by weight, the compression recovery rate of the pet sheet 1 can be increased to 94% or more.

[0066] The bending rigidity of the main body 10 of the pet sheet 1 according to the KES method is 0.20 gf cm 2 / cm] or less. The bending rigidity according to the KES method is measured, for example, using a large bending tester KES-FB-L manufactured by Kato Tech Co., Ltd. When measuring bending rigidity, a 10 cm x 10 cm test piece is cut out from the absorbent portion 13 of the pet sheet 1, one end of the test piece in the longitudinal direction is attached to the first chuck of the bending tester, and the other end of the test piece in the longitudinal direction is attached to the second chuck of the bending tester. Then, the first chuck is rotated around the second chuck, and the bending rigidity of the test piece bent thereby is measured using a torque detector. A similar test is performed on five test pieces, and the average of the measured values ​​is taken as the bending rigidity. The lower the measured bending rigidity, the more flexible the sheet.

[0067] The bending rigidity depends on the proportion of thermoplastic resin fibers in the entire absorbent core 41, and tends to decrease as the proportion of thermoplastic resin fibers increases. By making the proportion of thermoplastic resin fibers in the entire absorbent core 41 30% or more by weight, the bending rigidity of the main body 10 can be reduced to 0.20 [gf cm 2 / cm] or less. By reducing the bending rigidity of the main body 10, the main body 10 deforms in accordance with the superabsorbent polymer that swells upon absorbing urine, and the formation of irregularities on the surface of the pet sheet 1 is suppressed. Also, if the bending rigidity of the main body 10 is high, the folds may be stiff and may cause discomfort to the pet. The bending rigidity of the main body 10 can be reduced to 0.20 [gf cm] 2 / cm] or less, it is possible to suppress the discomfort felt by the pet.

[0068] As described above, in the pet sheet 1, the absorbent core 41 contains 30% or more thermoplastic resin fibers by weight. Unlike pulp, thermoplastic resin fibers do not contain hydroxyl groups and do not form hydrogen bonds. Therefore, when the pet sheet 1 is folded and compressed along the fold line L1, the formation of creases in the pet sheet 1 is suppressed. Therefore, as shown in FIG. 7 , when the pet sheet 1 stored in a folded state is removed from the package 50, the pet sheet 1 naturally unfolds and can be attached to the disposal sheet 100 as is. At this time, because the pet sheet 1 has an unfolding function, the pet sheet 1 is less likely to bend into a mountain shape on the disposal sheet 100, preventing the area where the pet sheet 1 is placed from appearing locally raised. This reduces the visual discomfort felt by the pet.

[0069] In addition, because the pet sheet 1 has an unfolding function, when a user removes the folded pet sheet 1 from the packaging 50, the pet sheet 1 unfolds naturally by grasping the first portion 11 or the second portion 12 of the pet sheet 1 with one hand. This reduces the user's effort of unfolding the pet sheet 1 with both hands. Furthermore, because the pet sheet 1 is less likely to develop creases, the pet sheet 1 can be stored in a tightly compressed state within the packaging 50. This allows the pet sheet 1 to be stored compactly.

[0070] Various experimental examples of the pet sheet 1 will be described below, but the present invention is not limited to the following experimental examples.

[0071] Figure 9 shows experimental results showing the relationship between the proportion of thermoplastic resin fibers in the absorbent core 41 as a whole and the angle θ between the first portion 11 and the second portion 12 of the pet sheet 1. Specifically, pet sheet samples A to F were prepared, each containing 35% by weight of superabsorbent polymer (SAP) in the absorbent core 41 as a whole and differing proportions of thermoplastic resin fibers. The above-described unfolding function test was performed using samples A to F, and the angle θ was measured. Furthermore, samples A to F after the unfolding function test were placed on the disposal sheet 100, and the height H (see Figure 2) from the surface of the disposal sheet 100 to the fold line L1 of samples A to F was measured. The visual discomfort was also evaluated by a sensory test. In the "Uncomfortable" category in Figure 9, "A" indicates minimal discomfort, "B" indicates slight discomfort, and "C" indicates significant discomfort.

[0072] Specifically, in Sample A, the proportion of pulp (hereinafter simply referred to as "pulp") primarily composed of cellulose fiber was 65% by weight, and the proportion of thermoplastic resin fiber was 0% by weight. In Sample B, the proportion of pulp was 52% by weight, and the proportion of thermoplastic resin fiber was 13% by weight. In Sample C, the proportion of pulp was 39% by weight, and the proportion of thermoplastic resin fiber was 26% by weight. In Sample D, the proportion of pulp was 32.5% by weight, and the proportion of thermoplastic resin fiber was 32.5% by weight. In Sample E, the proportion of pulp was 26% by weight, and the proportion of thermoplastic resin fiber was 39% by weight. In Sample F, the proportion of pulp was 0% by weight, and the proportion of thermoplastic resin fiber was 65% by weight.

[0073] 9, it was confirmed that the angle θ increases as the proportion of thermoplastic resin fibers in the entire absorbent core 41 increases. In particular, it was confirmed that if the proportion of thermoplastic resin fibers is 32.5% or more by weight, the angle θ becomes 151° or more, and the visual discomfort when the pet sheet is placed on the disposal sheet can be reduced.

[0074] 10 shows the results of an experiment showing the relationship between the proportion of thermoplastic resin fibers in the entire absorbent core 41 and the bending rigidity of the main body 10 of the pet sheet 1. In this experiment, the above-mentioned samples A to F were prepared, and test pieces measuring 10 cm x 10 cm were cut out from the absorbent parts of the samples A to F, and the bending rigidity of the test pieces was measured using a large bending tester KES-FB-L manufactured by Kato Tech Co., Ltd.

[0075] As shown in Fig. 10, it was confirmed that the bending rigidity decreases as the proportion of thermoplastic resin fibers in the entire absorbent core 41 increases. In particular, when the proportion of thermoplastic resin fibers is 32.5% by weight or more, the bending rigidity is reduced to 0.20 [gf cm 2 It was confirmed that the thickness could be reduced to less than [ / cm].

[0076] Figure 11 shows the results of an experiment showing the relationship between the proportion of thermoplastic resin fibers in the absorbent core 41 as a whole and the compression recovery rate of the main body 10 of the pet pad 1. In this experiment, samples A to F described above were prepared, and a 3.0 kg load was applied to samples A to F in a folded state in the thickness direction for 10 minutes. The thickness of samples A to F was measured 3 minutes after the load was released, and the ratio of the thickness of samples A to F in a folded state before and after the load was applied was defined as the compression recovery rate. As shown in Figure 11, it was confirmed that the compression recovery rate increases as the proportion of thermoplastic resin fibers in the absorbent core 41 as a whole increases. In particular, it was confirmed that a compression recovery rate of 94% or more can be achieved by setting the proportion of thermoplastic resin fibers to 32.5% or more by weight.

[0077] Although the pet sheet 1 according to various embodiments has been described above, the present invention is not limited to the above-described embodiments and various modifications can be made without departing from the spirit of the invention. In other words, it should be noted that the above-described embodiments are for illustrative purposes only and do not limit the scope of the present invention.

[0078] In the above embodiment, the thermoplastic resin fiber accounts for 30% or more by weight of the entire absorbent core 41, but the thermoplastic resin fiber may also account for 30% or less by weight. If the absorbent core 41 contains at least thermoplastic resin fiber made of olefin resin or PET resin, the formation of creases in the pet pad 1 can be suppressed.

[0079] In the above embodiment, the fold line L1 is a fold line for folding the pet sheet 1 in half, but the fold line L1 does not have to be a fold line as long as it crosses the absorbent core 41 and divides the main body portion 10 into the first portion 11 and the second portion 12. For example, the fold line L1 may extend in a direction inclined relative to the outer edge of the main body portion 10.

[0080] 7, the pet sheet 1 is folded in half along the fold line L1 so that the back surface 3a is located on the inside and is contained within the package 50, but the pet sheet 1 may also be folded in half along the fold line L1 so that the front surface 2a is located on the inside and contained within the package 50. In this case, the engaging portion 7 will come into contact with adjacent pet sheets 1 within the package 50, but the joining surface 7a of the engaging portion 7 is designed not to join with the back surface sheet 3, so adjacent pet sheets 1 are prevented from joining together.

[0081] The pet sheet 1 does not need to have the engaging portion 7. For example, an adhesive may be applied to part or the entire back surface 3a of the back sheet 3, and a release paper may be provided on the back surface 3a. In this case, the release paper can be peeled off before the back sheet 3 is attached to the treatment sheet 100.

[0082] The present disclosure includes the following contents.

[0083] [1] An absorbent sheet comprising a main body portion having a water-permeable top sheet, a back sheet opposite the top sheet, and an absorbent body arranged between the top sheet and the back sheet, wherein the absorbent body has an absorbent core containing thermoplastic resin fibers, and the proportion of the thermoplastic resin fibers in the entire absorbent core is 30% by weight or more, and wherein, after a load of 3.0 kg is applied in the thickness direction to the main body portion folded along a fold line that crosses the absorbent core and divides the main body portion into a first portion and a second portion for 10 minutes, when the first portion is lifted vertically, the second portion naturally separates from the first portion, and the angle between the first portion and the second portion becomes 145° or more.

[0084] [2] The absorbent sheet according to [1], wherein the fold line is a fold line for folding the main body portion in half so that the back sheet is disposed inside.

[0085] [3] The absorbent sheet according to [1] or [2], wherein the proportion of the thermoplastic resin fibers in the entire absorbent core is 65% or more by weight.

[0086] [4] The absorbent sheet according to any one of [1] to [3], wherein the average fiber length of the thermoplastic resin fibers is 0.2 mm or more and 8.0 mm or less.

[0087] [5] The absorbent sheet according to any one of [1] to [4], wherein the absorbent body further comprises a core wrap covering the absorbent core, and the average fiber length of the thermoplastic resin fibers is shorter than the average fiber length of the core wrap.

[0088] [6] The absorbent sheet according to [5], wherein the average fiber length of the core wrap is 100 mm or more.

[0089] [7] The core wrap includes a first core wrap sheet arranged between the top sheet and the absorbent core, and a second core wrap sheet arranged between the back sheet and the absorbent core, and at least one of the first core wrap sheet and the second core wrap sheet contains synthetic fibers. An absorbent sheet as described in [5] or [6].

[0090] [8] The absorbent sheet according to [7], wherein both the first core wrap sheet and the second core wrap sheet contain the synthetic fibers.

[0091] [9] The absorbent sheet according to [7], wherein the first core wrap sheet is made of tissue and the second core wrap sheet is made of nonwoven fabric.

[0092]

[10] The absorbent sheet according to [9], wherein the nonwoven fabric is an SMS nonwoven fabric.

[0093]

[11] The absorbent sheet according to any one of [1] to

[10] , wherein a load of 3.0 kg is applied to the main body portion folded along the fold lines from the thickness direction for 10 minutes, and the ratio of the thickness of the main body portion folded along the fold lines to the thickness of the main body portion before pressure is applied is 94% or more 3 minutes after the load is released.

[0094]

[12] The absorbent sheet according to any one of [1] to

[11] , wherein the basis weight of the thermoplastic resin fiber in the region on the fold line of the absorbent core is smaller than the basis weight of the thermoplastic resin fiber in the region other than the region on the fold line of the absorbent core.

[0095]

[13] The absorbent sheet according to

[12] , wherein the absorbent core contains the thermoplastic resin fibers in the region on the fold line.

[0096]

[14] The bending rigidity of the main body according to the KES method is 0.20 [gf cm 2 The absorbent sheet according to any one of [1] to

[13] , wherein the surface roughness is less than or equal to [cm].

[0097]

[15] The absorbent sheet according to any one of [1] to

[14] , wherein the thermoplastic resin fibers are composed of an olefin resin or a PET resin.

[0098]

[16] The absorbent sheet according to any one of [1] to

[15] , wherein the back sheet has an inner surface facing the absorbent body and an outer surface opposite to the outer surface, and the outer surface of the back sheet is provided with an engagement portion that engages with an excrement disposal sheet that absorbs pet excrement, and the engagement portion is positioned at a position offset from the fold line.

[0099]

[17] The area of ​​the main body in a plan view is 400 cm ２ The absorbent sheet according to any one of [1] to

[16] , which is as follows:

[0100]

[18] An absorbent sheet comprising a main body including a water-permeable top sheet, a back sheet opposite the top sheet, and an absorbent body arranged between the top sheet and the back sheet, wherein the absorbent body has an absorbent core containing thermoplastic resin fibers made of olefin resin or PET resin, wherein a fold line is formed in the main body and crosses the absorbent core, and the back sheet has an inner surface facing the absorbent body and an outer surface opposite the outer surface, and wherein the outer surface of the back sheet is provided with an engagement portion that engages with an excrement disposal sheet that absorbs pet excrement, and the engagement portion is arranged in a position offset from the fold line.

[0101]

[19] The absorbent sheet according to

[18] , wherein the proportion of the thermoplastic resin fibers in the entire absorbent core is 30% or more by weight.

[0102]

[20] The absorbent sheet according to

[18] or

[19] , which is used by overlapping a part of an excrement disposal sheet for absorbing pet excrement, and has an area smaller than the area of ​​the excrement disposal sheet.

[0103]

[21] The absorbent sheet according to any one of

[18] to

[20] , wherein the thermoplastic resin fibers are derived from pulverized nonwoven fabric.

[0104] 1...pet sheet (absorbent sheet), 2...surface sheet, 2a...surface, 3...back sheet, 3a...back surface (outer surface), 4...absorbent body, 7...engagement portion, 10...main body portion, 11...first portion, 12...second portion, 41...absorbent core, 42...core wrap, 42a...first core wrap sheet, 42b...second core wrap sheet, 100...excrement disposal sheet, L1...fold line, U...excrement, θ...angle.

Claims

1. An absorbent sheet comprising a main body having a water-permeable top sheet, a back sheet opposite the top sheet, and an absorbent body disposed between the top sheet and the back sheet, wherein the absorbent body has an absorbent core containing thermoplastic resin fibers, the proportion of the thermoplastic resin fibers in the entire absorbent core being 30% or more by weight, and wherein, when a load of 3.0 kg is applied for 10 minutes in the thickness direction to the main body folded along a fold line that crosses the absorbent core and divides the main body into a first portion and a second portion, and then the first portion is lifted vertically, the second portion naturally separates from the first portion, such that the angle between the first portion and the second portion is 145° or more.

2. The absorbent sheet according to claim 1, wherein the fold line is a fold line for folding the main body portion in half so that the back sheet is disposed on the inside.

3. The absorbent sheet according to claim 1, wherein the proportion of said thermoplastic resin fibers in the entire absorbent core is 65% or more by weight.

4. The absorbent sheet according to claim 1, wherein the average fiber length of the thermoplastic resin fibers is 0.2 mm or more and 8.0 mm or less.

5. The absorbent sheet according to claim 1, wherein the absorbent body further comprises a core wrap covering the absorbent core, and the average fiber length of the thermoplastic resin fibers is shorter than the average fiber length of the core wrap.

6. The absorbent sheet according to claim 5, wherein the average fiber length of said core wrap is 100 mm or more.

7. The absorbent sheet of claim 5, wherein the core wrap comprises a first core wrap sheet disposed between the top sheet and the absorbent core, and a second core wrap sheet disposed between the back sheet and the absorbent core, and at least one of the first core wrap sheet and the second core wrap sheet comprises synthetic fibers.

8. The absorbent sheet of claim 7, wherein both said first core wrap sheet and said second core wrap sheet comprise said synthetic fibers.

9. The absorbent sheet according to claim 7, wherein said first core wrap sheet is made of tissue and said second core wrap sheet is made of nonwoven fabric.

10. The absorbent sheet according to claim 9, wherein the nonwoven fabric is an SMS nonwoven fabric.

11. The absorbent sheet according to claim 1, wherein a load of 3.0 kg is applied to the main body portion folded along the fold lines in the thickness direction for 10 minutes, and the ratio of the thickness of the main body portion 3 minutes after the load is released to the thickness of the main body portion before pressure is applied is 94% or more.

12. An absorbent sheet as described in claim 1, wherein the basis weight of the thermoplastic resin fibers in the fold line region of the absorbent core is smaller than the basis weight of the thermoplastic resin fibers in the absorbent core region other than the fold line region.

13. The absorbent sheet according to claim 12, wherein the absorbent core contains the thermoplastic resin fibers in the area on the fold line.

14. The bending rigidity of the main body according to the KES method is 0.20 [gf cm 2 2. The absorbent sheet according to claim 1, wherein the surface tension is less than or equal to [1 / cm].

15. The absorbent sheet according to claim 1, wherein the thermoplastic resin fibers are made of olefin resin or PET resin.

16. An absorbent sheet as described in claim 1, wherein the back sheet has an inner surface facing the absorbent body and an outer surface opposite the front surface, and the outer surface of the back sheet is provided with an engagement portion for engaging with an excrement disposal sheet that absorbs pet excrement, and the engagement portion is positioned at a position offset from the fold line.

17. The area of ​​the main body in plan view is 400 cm ２ 2. The absorbent sheet according to claim 1, wherein:

18. An absorbent sheet comprising a main body having a water-permeable top sheet, a back sheet opposite the top sheet, and an absorbent body arranged between the top sheet and the back sheet, wherein the absorbent body has an absorbent core containing thermoplastic resin fibers made of olefin resin or PET resin, wherein a fold line is formed in the main body and crosses the absorbent core, and wherein the back sheet has an inner surface facing the absorbent body and an outer surface opposite to the front surface, and wherein the outer surface of the back sheet is provided with an engagement portion that engages with an excrement disposal sheet that absorbs pet excrement, and wherein the engagement portion is arranged in a position offset from the fold line.

19. The absorbent sheet according to claim 18, wherein the proportion of said thermoplastic resin fibers in the entire absorbent core is 30% or more by weight.

20. The absorbent sheet according to claim 18, which is used by overlapping a portion of a pet waste disposal sheet for absorbing pet waste and has an area smaller than the area of ​​said pet waste disposal sheet.

21. The absorbent sheet of claim 18, wherein the thermoplastic resin fibers are derived from a comminuted nonwoven fabric.

Images