Hygienic paper and method for producing hygienic paper

Abstract

The present invention addresses the problem of provide hygienic paper that produces little paper dust during the production process and during use and that has good water absorbency. The present invention relates to hygienic paper comprising pulp fiber and a thermoplastic resin, wherein the content of the thermoplastic resin is 50-3000 ppm. The present invention also relates to a method for producing hygienic paper which contains pulp fiber and thermoplastic resin and in which the content of the thermoplastic resin is 50-3000 ppm.

Description

Sanitary paper and method for manufacturing sanitary paper

[0001] The present invention relates to sanitary paper and a method for producing sanitary paper.

[0002] In recent years, due to environmental concerns, efforts to eliminate plastic have been accelerating worldwide. As a result, many products are being converted to paper, and there is also a demand for recycled paper products. For example, recycled sanitary paper is being produced using waste paper such as sanitary paper broke, magazines, and copy paper.

[0003] On the other hand, when it comes to recycling paper products, paper products containing plastic are treated as prohibited waste paper, so many are disposed of without being recycled. However, in recent years, the need to recycle paper products containing plastic has increased, and technological advances have led to the advancement of recycling of paper-plastic composite products.

[0004] In addition to having excellent water absorption, sanitary paper is required to generate little paper dust during the manufacturing process (see, for example, Patent Document 1). Naturally, the same quality is required for sanitary paper manufactured using recycled materials.

[0005] JP 2016-198472 A

[0006] Sanitary paper manufactured using recycled materials such as waste paper is also required to have excellent water absorbency and to generate little paper dust during the manufacturing process and during use. However, with conventional technology, it has been difficult to achieve both excellent water absorbency and reduced paper dust generation.

[0007] Therefore, in order to solve these problems of the conventional technology, the inventors have conducted research with the aim of providing sanitary paper that generates little paper dust during the manufacturing process and during use and has good water absorbency.

[0008] Examples of specific embodiments of the present invention are given below.

[0009] [1] Sanitary paper containing pulp fibers and a thermoplastic resin, with a thermoplastic resin content of 50 to 3,000 ppm. [2] Sanitary paper according to [1], in which the curl value of the pulp fibers contained in the pulp slurry obtained by disintegrating the sanitary paper in accordance with JIS P 8220-1:2012 is 15% or less. [3] Sanitary paper according to [1] or [2], in which the sanitary paper contains softwood pulp fibers and hardwood pulp fibers, with N being the content of softwood pulp fibers relative to the total pulp mass and L being the content of hardwood pulp fibers relative to the total pulp mass, and N:L being 0:100 to 40:60. [4] Sanitary paper according to any one of [1] to [3], in which the fibrillation degree of the pulp fibers contained in the pulp slurry obtained by disintegrating the sanitary paper in accordance with JIS P 8220-1:2012 is 0.3% or more. [5] The sanitary paper according to any one of [1] to [4], wherein the proportion of fibers with a length-weighted fiber length of 1.2 mm or more contained in a pulp slurry obtained by defibrating the sanitary paper in accordance with JIS P 8220-1:2012 is 5.0% or more. [6] The sanitary paper according to any one of [1] to [5], wherein the thermoplastic resin is a polyolefin resin. [7] The sanitary paper according to any one of [1] to [6], wherein the sanitary paper contains pulp fibers and a thermoplastic resin derived from laminated waste paper from liquid containers. [8] The sanitary paper according to [7], wherein the laminated waste paper contains softwood pulp fibers and hardwood pulp fibers, and wherein, where N is the content of softwood pulp fiber relative to the total pulp mass contained in the laminated waste paper and L is the content of hardwood pulp fiber relative to the total pulp mass, N:L = 0:100 to 40:60. [9] The sanitary paper according to JAPAN TAPPI Paper Pulp Testing Method No. 32-2:2000.

[10] A method for producing sanitary paper comprising pulp fibers and a thermoplastic resin, the thermoplastic resin content being 50 to 3000 ppm.

[11] A method for producing sanitary paper according to

[10] , comprising the steps of: defibrating pulp fibers from laminated waste paper from liquid containers containing thermoplastic resin and pulp fibers to obtain a pulp slurry containing thermoplastic resin and pulp fibers; and making paper from the pulp slurry.

[12] The method for producing sanitary paper according to

[11] , further comprising a step of crushing and washing laminated waste paper from liquid containers containing thermoplastic resin and pulp fibers before the step of producing paper from the pulp slurry.

[13] The method for producing sanitary paper according to

[11] or

[12] , further comprising a drying step after the step of producing paper from the pulp slurry.

[0010] The present invention will be described in detail below. The following description may be based on representative embodiments or specific examples, but the present invention is not limited to such embodiments. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0011] (Sanitary Paper) This embodiment relates to sanitary paper that contains pulp fibers and a thermoplastic resin, and has a thermoplastic resin content of 50 to 3000 ppm. In this embodiment, by setting the thermoplastic resin content within the above range, it is possible to produce sanitary paper that generates little paper dust during the manufacturing process and during use and has good water absorbency.

[0012] The sanitary paper of this embodiment is preferably one-ply or two or more-ply sanitary paper. The number of plies of sanitary paper refers to the number of overlapping sheets of sanitary paper base paper. The number of plies is more preferably one to four, and particularly preferably one ply.

[0013] Examples of the sanitary paper of this embodiment include toilet paper, kitchen paper, disposable hand towels, tissue paper, etc. The sanitary paper of this embodiment may also be a roll product obtained by winding up these sheet-like papers into a roll.

[0014] <Thermoplastic Resin> The thermoplastic resin contained in the sanitary paper of this embodiment may be either a natural resin or a synthetic resin, such as starch derivatives, casein, shellac, polyvinyl alcohol and its derivatives, acrylic resins, ionomer resins, maleic acid resins, urethane resins, polyester resins (such as polyethylene terephthalate), styrene-butadiene resins, vinyl chloride resins, polyolefin resins, ethylene-vinyl alcohol copolymers, ethylene-acrylic acid copolymers (EAA), ethylene-methacrylic acid copolymers (EMAA), ethylene-methyl methacrylate copolymers (EMMA), styrene-acrylic copolymers, and polyamide resins (such as nylon). Among these, the thermoplastic resin is preferably a polyolefin resin, and examples of polyolefin resins include polyethylene, polypropylene, and ethylene-α-olefin copolymers (such as ethylene-propylene copolymers). The polyolefin resin is preferably polyethylene or polypropylene, with polyethylene being particularly preferred. As the polyethylene, for example, high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE) are preferably used.

[0015] The density of the polyolefin resin is 0.900 g / cm ３ It is preferable that the density is 0.910 g / cm or more. ３ The density of the polyolefin resin is more preferably 0.990 g / cm or more. ３ Preferably, it is 0.970 g / cm or less. ３ More preferably, it is 0.950 g / cm or less. ３ The melting point of the polyolefin resin is preferably 85° C. or higher, and more preferably 90° C. or higher. The melting point of the polyolefin resin is preferably 170° C. or lower, more preferably 150° C. or lower, and even more preferably 130° C. or lower.

[0016] The content of thermoplastic resin contained in the sanitary paper is preferably 50 ppm or more, more preferably 100 ppm or more, even more preferably 150 ppm or more, and even more preferably 200 ppm or more. The content of thermoplastic resin is preferably 3000 ppm or less, more preferably 2500 ppm or less, and even more preferably 2000 ppm or less. By setting the content of thermoplastic resin at or above the lower limit, the thermoplastic resin is appropriately bound to a portion of the pulp fibers, thereby suppressing the generation of paper dust during the manufacturing process and use. On the other hand, by setting the content of thermoplastic resin at or below the upper limit, the pulp fibers, which exhibit excellent water absorption, are prevented from being coated with the thermoplastic resin, resulting in sanitary paper with excellent water absorption.

[0017] The content of thermoplastic resin contained in sanitary paper can be controlled by adjusting the content of thermoplastic resin contained in the pulp slurry used in producing the sanitary paper. For example, a predetermined amount of thermoplastic resin may be added to the pulp slurry. Alternatively, as described below, the content of thermoplastic resin may be controlled by appropriately controlling the type and content of thermoplastic resin-containing waste paper used as recycled raw material (e.g., thermoplastic resin-laminated waste paper or waste paper containing a thermoplastic resin sheet). In this embodiment, the thermoplastic resin contained in the sanitary paper is preferably a thermoplastic resin derived from thermoplastic resin-containing waste paper.

[0018] In this embodiment, the thermoplastic resin is uniformly dispersed throughout the entire sanitary paper. For example, when the sanitary paper is divided into three equal parts in the thickness direction, the thermoplastic resin content in the three regions is within ±10%.

[0019] Measuring the thermoplastic resin content of sanitary paper involves an extraction process to separate the thermoplastic resin contained in the sanitary paper, as described below, and an analysis process to quantify the thermoplastic resin content using pyrolysis GC / MS. In the extraction process, sanitary paper is sampled and the thermoplastic resin in the sanitary paper is extracted using a high-speed solvent extraction device (Buchi, E-916). The extraction conditions are an extraction temperature of 180°C, an extraction pressure of 150 bar, and an extraction solvent of xylene (special grade, Wako Pure Chemical Industries). The paper is then loaded into the extraction device, and two extraction cycles of extract are collected. After extraction, the solvent is removed using a rotary evaporator (water bath at 60°C), and the paper is dried at 105°C for 12 hours to fully dry the paper, thereby obtaining the thermoplastic resin in the sanitary paper. In the subsequent analysis process, an appropriate amount of xylene is added to the extracted thermoplastic resin to achieve a concentration of 2-5 mg / ml, and the paper is dissolved at 130°C for 2 hours, with stirring during the process. Next, the xylene solution of the extract dissolved in the Eco Cup whose tare weight has been measured is placed in such a way that the extract amount is 50 to 200 μg, and the solvent is evaporated at 105°C for 2 hours, and the amount of the extract to be analyzed is measured. The extract is measured using a pyrolysis GC / MS (Shimadzu Corporation GC / MS-QP2010) to quantify the amount of thermoplastic resin. When the thermoplastic resin is polyethylene, the pyrolysis GC / MS measurement conditions are as follows: Polyethylene standard: (Tosoh 07C03C, LDPE) Column: HP-5MS (length: 30 m, inner diameter: 0.250 mm, thickness: 0.25 μm) Analysis conditions: pyrolysis temperature = 600°C, injection port temperature = 320°C, split ratio = 1:60, interface temperature = 280°C, GC column temperature conditions = 40°C (hold for 3 minutes) → 10°C / min → 325°C (hold for 15 minutes), ion source temperature = 200°C Detection: m / z 29-600 (quantitation was calculated using the mass chromatogram area value of 1,19-eicosadiene (C20) at m / z 82)

[0020] The above analytical method is an analytical method when the thermoplastic resin is polyethylene, but when quantifying the content of a thermoplastic resin other than polyethylene, the analysis can be performed in the same manner by appropriately changing the standard, analytical conditions, and quantitative m / z.

[0021] <Pulp Fiber> The sanitary paper of this embodiment contains pulp fiber. The pulp fiber content in the sanitary paper is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more. The upper limit of the pulp fiber content in the sanitary paper is the remainder excluding the thermoplastic resin.

[0022] Pulp fibers include fibers made from wood pulp, non-wood pulp, and deinked pulp. Examples of wood pulp include chemical pulps such as hardwood pulp (hardwood kraft pulp (LKP)), softwood pulp (softwood kraft pulp (NKP)), sulfite pulp (SP), dissolving pulp (DP), soda pulp (AP), unbleached kraft pulp (UKP), and oxygen-bleached kraft pulp (OKP). Other examples include semi-chemical pulps such as semi-chemical pulp (SCP) and chemi-ground wood pulp (CGP), and mechanical pulps such as groundwood pulp (GP) and thermomechanical pulp (TMP, BCTMP). Examples of non-wood pulp include cotton-based pulps such as cotton linter and cotton lint, non-wood pulps such as hemp, straw, and bagasse, and cellulose, chitin, and chitosan isolated from sea squirts and seaweed. The deinked pulp may be made from recycled paper. The pulp may be one of the above-mentioned types alone or a mixture of two or more types.

[0023] The pulp fibers preferably include softwood pulp fibers and hardwood pulp fibers, and for example, it is more preferable to use a combination of softwood kraft pulp (NKP) fibers and hardwood kraft pulp (LKP) fibers. In this embodiment, it is also preferable to use deinked pulp fibers in combination as pulp fibers, and it is preferable to include deinked pulp fibers made from recycled paper.

[0024] The sanitary paper of this embodiment preferably contains softwood pulp fibers and hardwood pulp fibers. Here, where N is the content (parts by mass) of softwood pulp fibers relative to the total pulp mass, and L is the content (parts by mass) of hardwood pulp fibers relative to the total pulp mass, the N:L ratio is preferably 0:100 to 40:60, more preferably 0:100 to 20:80, and even more preferably 0:100 to 10:90. The content of each pulp fiber can be measured according to JIS P 8120:1998.

[0025] The fibrillation degree of the pulp fibers contained in the pulp slurry obtained by defibrating the sanitary paper of this embodiment in accordance with JIS P 8220-1:2012 is preferably 0.2% or more, more preferably 0.4% or more, and even more preferably 0.5% or more. Furthermore, the fibrillation degree of the pulp fibers contained in the sanitary paper is preferably 1.5% or less. By ensuring that the fibrillation degree of the pulp fibers contained in the sanitary paper is equal to or greater than the above lower limit, the surface area of ​​the pulp fibers increases, and the water absorbency of the sanitary paper can be more effectively improved. The fibrillation degree can be adjusted to a desired range by appropriately adjusting the defibration temperature; increasing the defibration temperature increases the fibrillation degree.

[0026] The degree of fibrillation of pulp fibers is the degree of external fibrillation and is expressed by the following formula (1) described in H. R. Motamedian et al., “Mechanisms of strength and stiffness improvement of paper after PFI refining with a focus on the effect of fines”, Cellulose (2019) 26:4099-4124.

[0027]

[0028] In formula (1), External fibrillation means the degree of external fibrillation, i.e., the degree of fibrillation, and A Ｆ means the area from above the fiber, and A Ｅｘｆmeans the total area of ​​the external fibrils.

[0029] The sanitary paper of this embodiment contains a pulp slurry obtained by defibrating the paper in accordance with JIS P 8220-1:2012. The amount of long pulp fibers contained in the pulp slurry is preferably 5.0% or more, more preferably 6.0% or more, even more preferably 6.5% or more, and particularly preferably 7.0% or more. The amount of long pulp fibers is preferably 30.0% or less. By ensuring that the amount of long pulp fibers is equal to or greater than the above lower limit, it is possible to prevent short fibers from falling off due to friction during the manufacturing process or use, thereby more effectively reducing the generation of paper dust.

[0030] In this specification, the term "long fibers" refers to fibers having a length-weighted fiber length of 1.2 mm or more, and the amount of long fibers refers to the ratio (percentage of number) of the number of fibers having a length-weighted fiber length of 1.2 mm or more to the total number of pulp fibers contained in the pulp slurry. The percentage of the number of long fibers is measured in accordance with JIS P 8226:2006. Specifically, the number of fibers (n ｉ The length-weighted percentage of fibers (f ｉ ') is calculated using the following formula (2):

[0031]

[0032] f ｉ ': Percentage of length-weighted fiber count (%) n ｉ : Number of fibers in the i-th length range l ｉ : the center of the i-th length range in millimeters Σn ｉ : Total number of fibers Σn ｉ l ｉ : n calculated for all length ranges ｉ l ｉ the sum of

[0033] The percentage of long fibers is the percentage of long fibers expressed by formula (2). For long fibers, the percentage of long fibers expressed by formula (2) is calculated for each fraction of fibers with a fiber length of 1.2 mm or more, and the sum of these is taken as the percentage of long fibers. More specifically, the FS-5 UHD base unit manufactured by Valmet used in the examples measures the number of fibers in the following six fractions (Fraction 1 to Fraction 6): Fraction 1: fiber length less than 0.2 mm Fraction 2: fiber length 0.2 mm or more and less than 0.6 mm Fraction 3: fiber length 0.6 mm or more and less than 1.2 mm Fraction 4: fiber length 1.2 mm or more and less than 2.0 mm Fraction 5: fiber length 2.0 mm or more and less than 3.2 mm Fraction 6: fiber length 3.2 mm or more and less than 7.6 mm When calculating the percentage of the number of long fibers, the percentage (fi') of the number of length-weighted fibers is calculated for each of Fraction 4, Fraction 5, and Fraction 6, and the sum of these is the percentage of the number of long fibers (%).

[0034] The curl value of the pulp fibers contained in the pulp slurry obtained by defibrating the sanitary paper of this embodiment in accordance with JIS P 8220-1:2012 is preferably 15% or less, more preferably 13% or less, even more preferably 12% or less, even more preferably 11% or less, and particularly preferably 10% or less. The lower limit of the curl value of the pulp fibers is not particularly limited, but is preferably 3.0% or more. The curl value is an index that represents the gentle bending state of the fibers themselves. The closer to 0%, the more linear the fibers are and the less curl there is, i.e., the higher the curl value, the higher the elastic modulus of the single fibers. Therefore, by setting the curl value of the pulp fibers to the above upper limit or less, the elastic modulus of the pulp single fibers can be increased, and as a result, paper dust that falls off due to friction during the manufacturing process and use can be more effectively reduced.

[0035] The curl value of pulp is expressed as follows, using the fiber length (contour length, L1) when the pulp fiber is straightened and the fiber length (the distance between the two furthest points on the same fiber, L2) when the fiber is curled: Curl value (%) = (L1 - L2) / L1 × 100. Here, fiber length (L1) and fiber length (L2) are length-weighted average values ​​calculated for fibers measured with L1 between 0.2 mm and 7.6 mm. L1 and L2 are calculated by image processing. Image processing (measuring the contour length) is performed to obtain the longest fiber length, and image processing (measuring the length of the two furthest points on the same fiber) is performed to obtain the longest length in a curled (bent) state. The curl value can be adjusted to a desired range by appropriately adjusting the type of pulp raw material used. In general, softwood pulp tends to have a higher curl value than hardwood pulp, and hardwood pulp also tends to have a higher curl value than recycled paper pulp. Furthermore, increasing the concentration of the pulp slurry during beating of the pulp raw material tends to increase the curl value, so the curl value of the pulp that makes up sanitary paper can be adjusted by adjusting the concentration of the pulp slurry during beating.

[0036] <Optional Components> Examples of optional components include dry strength agents, wet strength agents, and softeners. Examples of dry strength agents include cationized starch, polyacrylamide (PAM), and carboxymethyl cellulose (CMC). Examples of wet strength agents include polyamide epichlorohydrin, urea, melamine, and thermally crosslinkable polyacrylamide. Examples of softeners include anionic surfactants, nonionic surfactants, cationic surfactants, and zwitterionic surfactants. One of the optional components may be used alone, or two or more may be mixed and used. However, the content of the optional components is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less, based on the total mass of the sanitary paper.

[0037] <Physical Properties> The sanitary paper of this embodiment preferably has a water absorption rate of 130 seconds or less, more preferably 90 seconds or less, and even more preferably 50 seconds or less, as measured by the following measurement method (drop method). The lower limit of the water absorption rate is not particularly limited, and is preferably 0.3 seconds or more, for example. (Measurement Method) 100 μl (0.1 g) of ion-exchanged water is dropped onto the surface of the sanitary paper (100 mm x 100 mm) from a height of 10 mm. The water absorption rate is determined by measuring the time (visually) until the ion-exchanged water is absorbed by the sample surface and light reflection disappears. The drop method is performed in accordance with JAPAN TAPPI Paper and Pulp Testing Method No. 32-2:2000.

[0038] The sanitary paper of this embodiment suppresses the generation of paper dust. The degree of paper dust generation can be evaluated by calculating the white area ratio using the following evaluation method. Specifically, an adhesive film (NEION PET75-H109(20) manufactured by Nichiei Shinka Co., Ltd.) is attached to a metal roll with a diameter of 7 cm and a weight of 10 kg, and rolled twice over the sanitary paper at a speed of 60 bpm to cause paper dust to adhere to the adhesive film. The adhesive film is scanned (size 5 x 5 cm, image quality 400 dpi) and the entire image is binarized into white and black areas. The white area is considered to be paper dust, and the white area ratio (%) is calculated. The white area ratio is preferably 1.00% or less, more preferably 0.70% or less, and even more preferably 0.50% or less.

[0039] The thickness (total thickness) of the sanitary paper is preferably 20 μm or more, more preferably 25 μm or more, and even more preferably 30 μm or more. The thickness (total thickness) of the sanitary paper is preferably 300 μm or less, more preferably 250 μm or less, and even more preferably 200 μm or less. By maintaining the thickness of the sanitary paper within the above range, the feel of the paper during use can be improved and sufficient water absorption can be achieved. Furthermore, by maintaining the thickness within the above range, the stiffness during use can be reduced and the feel can be improved. When the sanitary paper is a two-ply product, the thickness (total thickness) of the sanitary paper is the measured value for the two-ply sanitary paper. The paper thickness is measured under a pressure of 2.0 kPa in accordance with ISO 12625-3:2014, using sanitary paper conditioned in a humidity-controlled environment specified in JIS P 8111:1998.

[0040] The basis weight of sanitary paper is 5 g / m ２ It is preferable that the content is 7 g / m or more. ２ More preferably, it is 10 g / m or more. ２ It is more preferable that the basis weight of the sanitary paper is 100 g / m or more. ２ Preferably, it is 80 g / m or less. ２ More preferably, it is 60 g / m or less. ２ It is more preferable that the basis weight is less than 1 / 2 ply. By setting the basis weight within the above range, sufficient strength can be obtained during use and excellent water absorption can be exhibited. The above basis weight is measured in accordance with JIS P 8124:2011 using sanitary paper that has been conditioned in a humidity-controlled environment as specified in JIS P 8111:1998. When the sanitary paper has two or more plies, the above basis weight is the measured value for one ply.

[0041] The density of sanitary paper is 0.05 g / cm ３ It is preferable that the density is 0.10 g / cm or more. ３ It is more preferable that the density of the sanitary paper is 0.50 g / cm or more. ３By setting the density within the above range, sufficient strength can be obtained during use and excellent water absorption can be exhibited. The density of sanitary paper is calculated using the following formula based on the basis weight and paper thickness measured as described above, in accordance with JIS P 8118:2014. Density (g / cm ３ )=Basic weight (g / m ２ ) / Paper thickness (μm)

[0042] The geometric mean value of the dry tensile strengths in the longitudinal and transverse directions of sanitary paper (average dry tensile strengths) is preferably 0.20 kN / m or more, more preferably 0.30 kN / m or more, and even more preferably 0.40 kN / m or more. Furthermore, the geometric mean value of the dry tensile strengths in the longitudinal and transverse directions of sanitary paper (average dry tensile strengths) is preferably 5.0 kN / m or less, more preferably 4.0 kN / m or less, even more preferably 3.0 kN / m or less, and even more preferably 2.0 kN / m or less. Here, the dry tensile strength of sanitary paper is measured in accordance with JIS P 8113:2006. Sanitary paper samples are cut to a width of 15 mm and a test length of 180 mm, and measurements are taken 10 times each under conditions of a span length of 100 mm and a pulling speed of 50 mm / min, and the geometric mean value of the dry tensile strengths in the longitudinal direction and the transverse direction (average dry tensile strengths) is calculated. The dry tensile strength can be measured using, for example, a horizontal tensile tester (Kumagaya Riki Kogyo Co., Ltd.) in an environment conforming to JIS P 8111:1998 (temperature 23±1°C, relative humidity 50±2%).

[0043] <Recycled Raw Materials> The sanitary paper of this embodiment is preferably manufactured using recycled raw materials. That is, the sanitary paper of this embodiment is sanitary paper containing recycled raw materials (recycled sanitary paper). Here, the recycled raw materials constituting the sanitary paper of this embodiment are preferably waste paper, and the waste paper preferably includes thermoplastic resin-containing waste paper (e.g., thermoplastic resin-laminated waste paper or waste paper containing a thermoplastic resin sheet), and particularly preferably includes laminated waste paper (thermoplastic resin-laminated waste paper) derived from liquid containers. Examples of liquid containers include beverage containers, liquid seasoning containers, and detergent containers. Specific examples include paper cups, paper cups, milk cartons, and aseptic containers. The proportion of thermoplastic resin-containing waste paper relative to the total mass of the recycled raw materials used to manufacture the sanitary paper of this embodiment is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more. Furthermore, the proportion of thermoplastic resin-containing waste paper is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less.

[0044] In the thermoplastic resin-containing waste paper, it is preferable that the thermoplastic resin is not printed. By using such thermoplastic resin-containing waste paper, it is possible to effectively increase the adhesiveness of the thermoplastic resin to the pulp fibers in the sanitary paper.

[0045] The recycled raw materials constituting the sanitary paper of this embodiment preferably contain thermoplastic resin-containing waste paper, and in this case, the sanitary paper contains pulp fibers derived from thermoplastic resin-containing waste paper and thermoplastic resin derived from thermoplastic resin-containing waste paper. In particular, the sanitary paper preferably contains pulp fibers derived from laminated waste paper from liquid containers and thermoplastic resin derived from laminated waste paper from liquid containers.

[0046] The content of thermoplastic resin contained in the thermoplastic resin-containing waste paper is preferably 1% by mass or more, more preferably 5% by mass or more, and particularly preferably 10% by mass or more. The content of thermoplastic resin contained in the thermoplastic resin-containing waste paper is preferably 50% by mass or less, more preferably 40% by mass or less, and particularly preferably 30% by mass or less.

[0047] The thermoplastic resin-containing waste paper preferably contains softwood pulp fibers and hardwood pulp fibers in addition to the thermoplastic resin. If the content of softwood pulp fibers relative to the total pulp mass contained in the thermoplastic resin-containing waste paper is N and the content of hardwood pulp fibers relative to the total pulp mass is L, then it is preferable that N:L = 0:100 to 40:60.

[0048] The sanitary paper of this embodiment may further contain deinked pulp fibers or recycled corrugated cardboard pulp fibers made from recycled paper. Examples of deinked pulp include recycled paper pulp (Kent recycled paper pulp) made from scraps of coated printing paper collected from bookbinding and printing factories, etc., recycled magazine pulp, recycled flyer pulp, recycled newspaper pulp, recycled office paper pulp, recycled communication paper pulp, recycled cardboard pulp, and recycled paper pulp from folding cartons.

[0049] The recycled raw materials that make up the sanitary paper may be a combination of thermoplastic resin-free waste paper that does not contain thermoplastic resin and thermoplastic resin-containing waste paper. In this case, the proportion of thermoplastic resin-free waste paper relative to the total mass of the recycled raw materials used to manufacture the sanitary paper of this embodiment is preferably 99% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less. Furthermore, the proportion of thermoplastic resin-free waste paper is preferably 70% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more.

[0050] The sanitary paper of this embodiment may further contain virgin pulp fibers, in which case the proportion of virgin pulp fibers relative to the total mass of pulp fibers contained in the sanitary paper of this embodiment is preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 80% by mass or less, and particularly preferably 75% by mass or less.

[0051] It is preferable that all of the pulp fibers contained in the sanitary paper of this embodiment are pulp fibers derived from recycled materials. Thus, the sanitary paper of this embodiment is preferably 100% recycled sanitary paper.

[0052] (Method for producing sanitary paper) This embodiment relates to a method for producing sanitary paper containing pulp fibers and a thermoplastic resin, where the thermoplastic resin content is 50 to 3000 ppm. The method for producing sanitary paper of this embodiment may include a step of adding the thermoplastic resin to a pulp slurry containing pulp fibers so that the thermoplastic resin content is 50 to 3000 ppm.

[0053] The method for producing sanitary paper of this embodiment preferably includes a step of defibrating pulp fibers from thermoplastic resin-containing waste paper containing thermoplastic resin and pulp fibers to obtain a pulp slurry containing thermoplastic resin and pulp fibers, and a step of making a paper from the pulp slurry.Of these, the method for producing sanitary paper of this embodiment more preferably includes a step of defibrating pulp fibers from laminated waste paper from liquid containers containing thermoplastic resin and pulp fibers to obtain a pulp slurry containing thermoplastic resin and pulp fibers, and a step of making a paper from the pulp slurry.

[0054] In the manufacturing method of this embodiment, it is preferable to disperse a predetermined amount of thermoplastic resin in the pulp slurry. For example, a pulp slurry containing thermoplastic resin and pulp fibers can be obtained by pulverizing thermoplastic resin-containing waste paper used as a recycled raw material and dispersing the pulp in the pulp slurry. In this case, the content of the thermoplastic resin can be controlled by appropriately controlling the type and content of the thermoplastic resin-containing waste paper used as a recycled raw material.

[0055] In the process of defibrating pulp fibers from laminated waste paper from liquid containers containing thermoplastic resin and pulp fibers to obtain a pulp slurry containing thermoplastic resin and pulp fibers, the defibration temperature is preferably 10°C or higher, more preferably 15°C or higher. The defibration temperature is preferably 75°C or lower, more preferably 65°C or lower. By setting the defibration temperature within the above range, it becomes easy to control the degree of fibrillation of the pulp fibers within the desired range. This increases the surface area of ​​the pulp fibers, allowing the water absorbency of the sanitary paper to be more effectively improved.

[0056] In the process of disintegrating pulp fibers from laminated waste paper from liquid containers containing thermoplastic resin and pulp fibers to obtain a pulp slurry containing thermoplastic resin and pulp fibers, the concentration of the laminated waste paper at the time of disintegration is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 2.5% by mass or more. Furthermore, the concentration of the laminated waste paper at the time of disintegration is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less. In the disintegration process, the higher the concentration of the laminated waste paper, the larger the foreign matter (e.g., pieces of thermoplastic resin) that separates from the pulp fibers, making these foreign matter easier to remove in the dust removal process. However, the lower the concentration of the laminated waste paper, the smaller the foreign matter pieces become, making them more difficult to remove in the dust removal process. Therefore, by keeping the waste paper concentration of the laminated waste paper within the above range at the time of disintegration, it becomes easier to control the thermoplastic resin content in sanitary paper within the desired range.

[0057] In the step of obtaining the pulp slurry, in addition to the pulp fibers and the thermoplastic resin, optional components may be mixed into the pulp slurry. As the optional components, the optional components described above can be appropriately used.

[0058] The process for obtaining the pulp slurry may include a step of bleaching the pulp fiber raw material. As the bleaching agent used in the bleaching step, known bleaching agents such as oxygen bleaching agents and chlorine bleaching agents can be used.

[0059] The step of obtaining a pulp slurry may include a step of beating the pulp fibers. In the beating step, for example, a double-disc refiner or the like may be used for beating treatment. During the beating treatment, for example, the softwood pulp fibers and the hardwood pulp fibers may be beaten separately, or they may be mixed and then beaten.

[0060] In conventional technology, when thermoplastic resin is incorporated into sanitary paper, it tends to become a foreign substance, often degrading the quality of the sanitary paper, so when sanitary paper is produced using recycled raw materials, the thermoplastic resin is separated and removed. In this embodiment, by selectively using unprinted thermoplastic resin, the thermoplastic resin does not become a foreign substance and can be bound to part of the pulp fibers, thereby maintaining the quality of the sanitary paper.

[0061] Examples of paper machines for making paper from the pulp slurry include suction breast formers (cylinder type, Fourdrinier type), twin wire formers, cylinder formers (C-wrap, S-wrap), and crescent formers.

[0062] A papermaking machine that produces pulp slurry generally includes a wire section, a press section, a dryer section, a calendar section, and a reel section. The wire section is a process for dehydrating the supplied slurry to form a sheet. In the wire section, the pulp slurry is supplied to a forming unit to form a one-layer or two-layer sheet that will serve as the base paper for sanitary paper. Three-layer sanitary paper can also be produced by forming a three-layer sheet in the forming unit. In the forming unit, the component ratios of the pulp slurry that form each layer can be made different. This allows the properties of each layer that constitutes the sanitary paper to be different.

[0063] In the manufacturing method of this embodiment, it is preferable to further include a step of crushing and washing thermoplastic resin-containing waste paper derived from liquid containers containing thermoplastic resin and pulp fibers before the step of making paper from the pulp slurry. In the crushing and washing step, a crushing and washing machine is used, and a crushing step in which the thermoplastic resin-containing waste paper is crushed into small pieces using rotary blades, and a washing step in which the crushed thermoplastic resin-containing waste paper is washed with wash water are carried out consecutively. For example, this can be carried out using a crushing and washing machine (Paper Container Recycling Machine PPRS, manufactured by A-Tech Co., Ltd.). As the rotary blade used in the crushing step, it is preferable to use a uniaxial or biaxial rotary blade, and it is more preferable to use a biaxial rotary blade. Furthermore, the crush size can be adjusted by changing the number of rotary blades (number of hooks), and increasing the number of hooks allows for smaller crushing. When the crush size is set to 20 cm ２ ~150cm ２ It is preferable to adjust it so that

[0064] The washing water used in the washing step may be, for example, water, hot water, caustic soda water, ozone water, hydrogen peroxide water, etc., but it is preferable to use water. The flow rate of the washing water can be adjusted to any amount, but it is not recommended to use a flow rate of 0.1 m ３ / h or more, and 0.5 m ３ / h or more is more preferable, and 1.0 m ３ / h or more. ３ / h or less. After crushing and washing, the crushed pieces may be baled using a compressor.

[0065] In the manufacturing method of this embodiment, by providing this crushing and washing step, short fibers with a fiber length of 1.2 mm or less can be removed, which prevents short fibers from falling off due to friction during the manufacturing process or use, and as a result, the generation of paper dust can be more effectively reduced.

[0066] The manufacturing method of this embodiment preferably further includes a drying step after the step of making paper from the pulp slurry. In the drying step, the pulp sheet obtained in the papermaking step is heated and dried. The drying step is preferably, for example, a step of blowing hot air toward the wet paper or a step of pressing the wet paper against the outer surface of a Yankee dryer. The size of the Yankee dryer is preferably φ3000 mm to φ5500 mm. In the drying step using a Yankee dryer, crepe-like wrinkles can also be formed by scraping the dried paper from the Yankee dryer with a doctor blade (creping process). In this case, the crepe ratio is preferably 10 to 40%. The crepe ratio is calculated by (Yankee dryer speed - reel speed) / reel speed x 100. By maintaining the crepe ratio within the above range, the softness and strength of the sanitary paper can be effectively improved.

[0067] The drying temperature in the drying step is preferably 80°C or higher, more preferably 90°C or higher, and even more preferably 100°C or higher. The drying temperature is preferably 160°C or lower, and more preferably 140°C or lower. The papermaking speed in the drying step is preferably 500 m / min or higher, and more preferably 1000 m / min or higher. The papermaking speed in the drying step is preferably 3000 m / min or lower. By providing such a drying step, the thermoplastic resin melts and is appropriately bound to a portion of the pulp fibers, thereby preventing paper powder from falling off.

[0068] The manufacturing method of this embodiment may further include a calendering step after the drying step. The calendering step is carried out in a calender part, in which the surface of the dried sheet is stretched while being pressed to smooth the surface of the sheet.

[0069] The manufacturing method of this embodiment may include a step of winding the sanitary paper to form a roll (reel). In the step of forming the roll (reel), the winding may be performed while forming tearing perforations across the width at regular intervals along the length. In the end processing section of the winding, it is preferable to glue the end of the long sanitary paper discharged from the winding section along the width to prevent the long sanitary paper from unraveling. The resulting roll is cut to a specified width to produce a sanitary paper roll product.

[0070] The sanitary paper may be embossed before or after the process of forming the roll (winding). The embossing is performed by pressing the sheet with an embossing roll. By changing the pressing amount or pressing pressure of the embossing roll, an embossed shape with a predetermined embossing height can be formed in the sanitary paper.

[0071] The features of the present invention will be explained in more detail below with reference to examples and comparative examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be changed as appropriate 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.

[0072] Example 1 A pulp mixture of magazine waste paper pulp and crushed and washed thermoplastic resin-laminated waste paper pulp (paper cup container N:L=0:100, polyethylene resin content 15% by mass) in a mass ratio of 85:15 was disintegrated at 20°C for 15 minutes in a low-consistency pulper to obtain a thermoplastic resin-containing pulp slurry (pulp concentration 3%). The laminated waste paper was crushed and washed using a crushing and washing machine (manufactured by A-Tech, paper container recycling device PPRS, number of hooks: 6, washing water: water, flow rate: 1.5 m). ３Next, 0.25 parts by mass of polyacrylamide ("Hermid D420" manufactured by Harima Chemicals Co., Ltd.) as a dry strength agent and 0.08 parts by mass of polyamide epichlorohydrin ("WS4020" manufactured by Seiko PMC Co., Ltd.) as a wet strength agent were added to 100 parts by mass of the obtained pulp slurry (calculated as solid content) to prepare a paper stock. This paper stock was mixed with a cylinder paper machine at a set basis weight of 32 g / m ２ The paper was dried at a drying temperature of 125°C using a Yankee dryer with a diameter of 4880 mm and a paper speed of 1200 m / min, to obtain the sanitary paper of Example 1. The thermoplastic resin content was 2019 ppm.

[0073] (Example 2) Sanitary paper was obtained under the same conditions as in Example 1, except that a pulp mixture of magazine waste paper pulp and crushed and washed thermoplastic resin-laminated waste paper pulp (paper cup container N:L = 0:100, polyethylene resin content 15% by mass) in a mass ratio of 95:5 was used.

[0074] (Example 3) Sanitary paper was obtained under the same conditions as in Example 1, except that a pulp mixture of magazine waste paper pulp and crushed and washed thermoplastic resin-laminated waste paper pulp (paper cup container N:L = 0:100, polyethylene resin content 15% by mass) in a mass ratio of 99:1 was used.

[0075] Example 4 Sanitary paper was obtained under the same conditions as in Example 1, except that the pulper defibration temperature was set to 40°C.

[0076] Example 5 Sanitary paper was obtained under the same conditions as in Example 1, except that the pulper defibration temperature was set to 60°C.

[0077] (Example 6) Sanitary paper was obtained under the same conditions as in Example 1, except that a pulp mixture of magazine waste paper pulp and crushed and washed thermoplastic resin-laminated waste paper pulp (milk carton N:L = 40:60, polyethylene resin content 10% by mass) in a mass ratio of 85:15 was used.

[0078] (Example 7) Sanitary paper was obtained under the same conditions as in Example 1, except that a pulp mixture of magazine waste paper pulp and crushed and washed thermoplastic resin-laminated waste paper pulp (milk carton N:L = 40:60, polyethylene resin content 10% by mass) in a mass ratio of 95:5 was used.

[0079] (Example 8) Sanitary paper was obtained under the same conditions as in Example 1, except that a pulp mixture of magazine waste paper pulp and crushed and washed thermoplastic resin-laminated waste paper pulp (paper cup container N:L = 15:85, polyethylene resin content 15% by mass) in a mass ratio of 85:15 was used.

[0080] Example 9 Sanitary paper was obtained under the same conditions as in Example 1, except that the thermoplastic resin-laminated recycled paper pulp was not crushed and washed.

[0081] (Example 10) Papermaking conditions were changed to a basis weight of 13 g / m ２ Sanitary paper was obtained under the same conditions as in Example 1, except that:

[0082] (Example 11) Papermaking conditions were changed to a basis weight of 44 g / m ２ Sanitary paper was obtained under the same conditions as in Example 1, except that:

[0083] Comparative Example 1 Sanitary paper was obtained under the same conditions as in Example 1, except that pulp made from 100% recycled magazine paper was used.

[0084] (Comparative Example 2) Sanitary paper was obtained under the same conditions as in Example 1, except that a pulp mixture of magazine waste paper pulp and crushed and washed thermoplastic resin-laminated waste paper pulp (paper cup container N:L = 0:100, polyethylene resin content 15% by mass) in a mass ratio of 70:30 was used.

[0085]

[0086] <Measurement and evaluation methods> (Basis weight) The sanitary papers obtained in the examples and comparative examples were conditioned for 24 hours in a humidity-controlled environment specified in JIS P 8111: 1998. Thereafter, the basis weight of the sanitary papers after humidity control was measured in accordance with JIS P 8124: 2011.

[0087] (Paper Thickness) The sanitary papers obtained in the Examples and Comparative Examples were conditioned for 24 hours in a humidity-controlled environment specified in JIS P 8111: 1998. The thickness of the sanitary papers after humidity control was measured under a pressure of 2.0 kPa in accordance with ISO 12625-3: 2014.

[0088] (Density) In accordance with JIS P 8118:2014, the density of the sanitary paper was calculated from the basis weight and paper thickness measured as described above using the following formula: Density (g / cm ３ )=Basic weight (g / m ２ ) / Paper thickness (μm)

[0089] (Thermoplastic Resin Content) The thermoplastic resin content was measured by an extraction process to separate the thermoplastic resin contained in the sanitary paper, as described below, and an analysis process to quantify the thermoplastic resin using pyrolysis GC / MS. <Extraction Process> 3-5 g of the sanitary paper obtained in the Examples and Comparative Examples was collected by dry weight and placed in an extraction cell (20 ml container). Next, the thermoplastic resin in the sanitary paper was extracted using a high-speed solvent extractor (machine: Buchi, E-916). The extraction conditions were an extraction temperature of 180°C, an extraction pressure of 150 bar, and an extraction solvent of xylene (special grade, Wako Pure Chemical Industries). A 100 ml vial (Maruem, Mighty Vial No. 8) was placed in the extractor, and two extraction cycles of extract were collected. After extraction, the solvent was removed using a rotary evaporator (water bath 60°C), and the sample was dried at 105°C for at least 12 hours to obtain the thermoplastic resin in the sanitary paper. <Analysis Step> An appropriate amount of xylene was added to the dried thermoplastic resin extracted from the vial above to a concentration of 2-5 mg / ml, and the mixture was dissolved at 130°C for 2 hours with stirring. Next, the xylene solution of the dissolved extract was placed in an Eco-cup whose tare weight had been measured so that the extract amount was 50-200 μg. The solvent was evaporated at 105°C for 2 hours, and the analytical sample amount of the extract was measured. The extract was analyzed using a pyrolysis GC / MS (Shimadzu GC / MS-QP2010) to quantify the thermoplastic resin content. The pyrolysis GC / MS measurement conditions were as follows: Polyethylene standard: (Tosoh 07C03C, LDPE) Column: HP-5MS (length: 30 m, inner diameter: 0.250 mm, thickness: 0.25 μm) Analysis conditions: pyrolysis temperature = 600°C, injection port temperature = 320°C, split ratio = 1:60, interface temperature = 280°C, GC column temperature conditions = 40°C (hold for 3 minutes) → 10°C / min → 325°C (hold for 15 minutes), ion source temperature = 200°C Detection: m / z 29-600 (quantitation was calculated using the mass chromatogram area value of 1,19-eicosadiene (C20) at m / z 82)

[0090] (Long Fiber Amount) The sanitary papers obtained in the Examples and Comparative Examples were disintegrated in accordance with JIS P 8220-1:2012 to obtain a pulp slurry with a concentration of 3% by mass. The obtained pulp slurry was sampled, and the fiber length was measured and calculated using a fiber length measuring device (product number FS-5 UHD base unit, manufactured by Valmet). The percentage of long fibers was measured in accordance with JIS P 8226:2006. Specifically, the number of fibers (n ｉ The length-weighted percentage of the number of fibers (f ｉ ') is calculated using the following formula (2):

[0091]

[0092] f ｉ ': Percentage of length-weighted fiber count (%) n ｉ : Number of fibers in the i-th length range l ｉ : the center of the i-th length range in millimeters Σn ｉ : Total number of fibers Σn ｉ l ｉ : n calculated for all length ranges ｉ l ｉ the sum of

[0093] For each fraction with a fiber length of 1.2 mm or more, the percentage of the number of fibers expressed by formula (2) was calculated, and the sum of these was taken as the percentage of the number of long fibers. More specifically, the number of fibers was counted in the following six fractions (Fraction 1 to Fraction 6). Fraction 1: fiber length less than 0.2 mm Fraction 2: fiber length 0.2 mm or more and less than 0.6 mm Fraction 3: fiber length 0.6 mm or more and less than 1.2 mm Fraction 4: fiber length 1.2 mm or more and less than 2.0 mm Fraction 5: fiber length 2.0 mm or more and less than 3.2 mm Fraction 6: fiber length 3.2 mm or more and less than 7.6 mm When calculating the proportion of the number of long fibers, the percentage (fi') of the number of length-weighted fibers was calculated for each of Fraction 4, Fraction 5, and Fraction 6, and the sum of these was defined as the proportion of the number of long fibers (%).

[0094] (Fibrillation degree) The sanitary papers obtained in the examples and comparative examples were disintegrated in accordance with JIS P 8220-1: 2012 to obtain a pulp slurry with a concentration of 3% by mass. The obtained pulp slurry was sampled and the fibrillation degree (%) was measured using a fiber length measuring device (product number FS-5 UHD base unit, manufactured by Valmet).

[0095] (Curl Value) The sanitary paper obtained in the Examples and Comparative Examples was disintegrated in accordance with JIS P 8220-1:2012 to obtain a pulp slurry with a concentration of 3% by mass. A portion of the obtained pulp slurry was sampled, and the curl value was measured using a fiber length measuring device (FS-5 UHD base unit, manufactured by Valmet). The curl value of pulp is expressed as follows, using the fiber length when the pulp fibers are straightened (contour length, L1) and the fiber length in a curled state (the distance between the two furthest points on the same fiber, L2): Curl Value (%) = (L1 - L2) / L1 x 100. Here, the fiber length (L1) and the fiber length (L2) were calculated as length-weighted average values ​​for fibers with L1 of 0.2 mm or more and 7.6 mm or less. L1 and L2 were calculated using image processing. For L1, image processing (measuring the contour length) was performed so that the fiber length was at its longest, and for L2, image processing (measuring the length of the two furthest points on the same fiber) was performed so that the length was at its longest in a curled (bent) state.

[0096] (Water absorption rate / water absorption) 100 μl (0.1 g) of ion-exchanged water was dropped onto sanitary paper (100 mm x 100 mm) from a height of 10 mm, and the time (visually) until the ion-exchanged water was absorbed from the sample surface and light reflection disappeared was measured and taken as the water absorption rate (based on JAPAN TAPPI Paper Pulp Test Method No. 32-2:2000). Water absorption was evaluated according to the following criteria: A: Water absorption rate value is 50 seconds or less B: Water absorption rate value is more than 50 seconds and less than 90 seconds C: Water absorption rate value is more than 90 seconds and less than 130 seconds D: Water absorption rate value is more than 130 seconds

[0097] (White area ratio / paper dust) An adhesive film (NEION PET75-H109(20) manufactured by Nichiei Shinka Co., Ltd.) was attached to a metal roll with a diameter of 7 cm and a weight of 10 kg, and rolled twice over sanitary paper at a speed of 60 bpm to adhere paper dust to the adhesive film. The adhesive film was then scanned (size 5 x 5 cm, image quality 400 dpi) and the entire film was binarized into white and black areas. The white areas were considered to be paper dust, and the white area ratio (%) was calculated. Paper dust was evaluated according to the following criteria: A: White area ratio is 0.50% or less B: White area ratio is more than 0.50% and 0.70% or less C: White area ratio is more than 0.70% and 1.00% or less D: White area ratio is more than 1.00%

[0098]

[0099] Compared to the comparative example, the examples produced less paper dust and had good water absorbency, whereas the comparative example did not achieve both suppression of paper dust production and good water absorbency.

Claims

1. Sanitary paper containing pulp fibers and a thermoplastic resin, the content of the thermoplastic resin being 50 to 3,000 ppm.

2. The sanitary paper according to claim 1, wherein the curl value of the pulp fibers contained in the pulp slurry obtained by disintegrating the sanitary paper in accordance with JIS P 8220-1:2012 is 15% or less.

3. The sanitary paper according to claim 1, which contains softwood pulp fiber and hardwood pulp fiber, and where N is the content of softwood pulp fiber relative to the total pulp mass and L is the content of hardwood pulp fiber relative to the total pulp mass, N:L = 0:100 to 40:

60.

4. The sanitary paper according to claim 1, wherein the fibrillation degree of the pulp fibers contained in the pulp slurry obtained by disintegrating the sanitary paper in accordance with JIS P 8220-1:2012 is 0.3% or more.

5. The sanitary paper according to claim 1, wherein the proportion of fibers with a length-weighted fiber length of 1.2 mm or more contained in the pulp slurry obtained by disintegrating the sanitary paper in accordance with JIS P 8220-1:2012 is 5.0% or more.

6. Sanitary paper according to claim 1, wherein the thermoplastic resin is a polyolefin resin.

7. The sanitary paper according to claim 1, comprising pulp fibers and a thermoplastic resin derived from laminated waste paper from liquid containers.

8. The sanitary paper according to claim 7, wherein the laminated waste paper contains softwood pulp fiber and hardwood pulp fiber, and where N is the content of softwood pulp fiber relative to the total pulp mass contained in the laminated waste paper, and L is the content of hardwood pulp fiber relative to the total pulp mass, N:L = 0:100 to 40:

60.

9. The sanitary paper according to claim 1, which has a water absorption rate of 130 seconds or less as measured by the method described in JAPAN TAPPI Paper Pulp Testing Method No. 32-2:2000.

10. A method for producing sanitary paper, comprising pulp fibers and a thermoplastic resin, wherein the content of the thermoplastic resin is 50 to 3,000 ppm.

11. A method for producing sanitary paper according to claim 10, comprising the steps of: defibrating pulp fibers from laminated waste paper from liquid containers containing thermoplastic resin and pulp fibers to obtain a pulp slurry containing thermoplastic resin and pulp fibers; and making paper from the pulp slurry.

12. The method for producing sanitary paper according to claim 11, further comprising a step of crushing and washing laminated waste paper originating from a liquid container containing a thermoplastic resin and pulp fibers before the step of making paper from the pulp slurry.

13. The method for producing sanitary paper according to claim 11, further comprising a drying step after the step of making paper from the pulp slurry.