EP3907328A1

EP3907328A1 - Toilet paper

Info

Publication number: EP3907328A1
Application number: EP20766224.8A
Authority: EP
Inventors: Shuta YASUI; Minoru Iwasaki
Original assignee: Daio Paper Corp
Current assignee: Daio Paper Corp
Priority date: 2019-03-06
Filing date: 2020-02-12
Publication date: 2021-11-10
Anticipated expiration: 2040-02-12
Also published as: KR102683635B1; JP2020141870A; JP7175801B2; WO2020179379A1; EP3907328B1; KR20210134645A; CN113330158B; CN113330158A; US20220127790A1; EP3907328A4

Abstract

To provide a toilet paper that provides an excellent thick feeling, has excellent water-disintegrability, has sufficient softness, provides a security feeling to a human body during use, and is environmentally friendly.

The problem is solved by a 3-ply or 4-ply toilet paper, each ply having a basis weight of 10.5 to 12.5 g/m², containing oxygen-pulped and non-chlorine-bleached softwood kraft pulp in an amount of 50 to 100% by mass of fibers, containing a cationic fatty acid amide-based softener, each ply having a paper thickness of 80 to 100 µm, having a paper thickness of 320 to 400 µm as the entire toilet paper, and having water-disintegrability of 10 seconds or less.

Description

Technical Field

The present invention relates to a toilet paper.

Background Art

In a toilet paper, a wiping property may be required when a shower toilet, which is also called a toilet with a washing function, is used (Patent Literature 1 below).
It is desirable that a toilet paper suitable for the shower toilet is a multi-ply product such as a 3-ply or 4-ply product because it is easy for a consumer to obtain a security feeling during use of thereof.
Incidentally, in a toilet paper, pulp, which is a fiber raw material, is generally bleached with a chlorine-based bleaching agent such as chlorine, chlorine dioxide, or sodium hypochlorite in order to increase whiteness. However, there is also a demand for, for example, an environmentally friendly product made from pulp for which the chlorine-based bleaching agent is not used among consumers who place importance on a security feeling to a human body and consideration for environment.
In addition, a toilet paper is generally manufactured from a fiber raw material obtained by mixing hardwood-derived pulp with a short fiber length and softwood-derived pulp with a long fiber length. Mainly, a toilet paper containing a large amount of hardwood-derived pulp that easily improves softness and a surface property is generally used.

Citation List

Patent Literature

Patent Literature 1: JP 2011-153387 A

Summary of Invention

Technical Problem

However, pulp that has not been bleached with a chlorine-based bleaching agent contains a large amount of remaining lignin, and fibers thereof are hard. For a toilet paper containing this pulp as a main fiber raw material, hardness and surface roughness are easily felt.
Meanwhile, in order for softness to be easily felt, it is known that the strength of paper is lowered by increasing the blending amount of hardwood pulp. However, when the blending amount of hardwood pulp is increased, water-disintegrability easily deteriorates. In particular, in a multi-ply product, water-disintegrability easily deteriorates. Therefore, a multi-ply product having a larger blending amount of hardwood pulp may be unsuitable for use in a shower toilet.
Furthermore, since hardwood pulp has a short fiber length, paper dust is likely to be generated. Furthermore, when a softener is used, paper dust is more likely to be generated.
Therefore, a main object of the present invention is to provide a toilet paper that provides a thick feeling that can make a user reassured during use thereof in a shower toilet, has sufficient softness, does not easily generate paper dust, has excellent water-disintegrability, and provides a security feeling to a human body during use thereof.

Solution to Problem

A first means to solve the above problems is

a 3-ply or 4-ply toilet paper
containing oxygen-pulped and non-chlorine-bleached softwood kraft pulp in an amount of 50 to 100% by mass of fibers, and
a cationic fatty acid amide-based softener,
wherein each ply has a basis weight of 10.5 to 12.5 g/m² and a paper thickness of 80 to 100 µm, and
the toilet paper has an overall paper thickness of 320 to 400 µm and water-disintegrability of 10 seconds or less.

Advantageous Effects of Invention

The above present invention provides a toilet paper that provides a thick feeling that can make a user reassured during use thereof in a shower toilet, has sufficient softness, does not easily generate paper dust, has excellent water-disintegrability, and provides a security feeling to a human body during use thereof.

Brief Description of Drawings

Fig. 1 is a plan view of an embossment according to an embodiment of the present invention.
Fig. 2 is a schematic view for explaining a procedure for measuring the depth of the embossment according to the present invention.
Fig. 3 is a perspective view of a toilet roll according to an embodiment of the present invention.

Description of Embodiments

A toilet paper according to the present embodiment is a 3-ply or 4-ply product. That is, the toilet paper according to the present embodiment has three or four sheets stacked. When the toilet paper is a product of multi-ply exceeding 2-ply, such as a 3-ply or 4-ply product, the paper thickness of the entire paper is large while each ply is thin, and the paper can be hardly torn and can provide a security feeling while particularly "softness" is easily felt.
Note that a 2-ply product hardly exhibits a thick feeling, and is likely to provide a poor security feeling when the paper absorbs a large amount of water and wipes the water after use in a shower toilet. In addition, when the toilet paper is a 5 or more-ply product, even if each ply is thin, softness is hardly felt when the skin is wiped with the toilet paper. In addition, when a 5 or more-ply product is used at the basis weight and the paper thickness per ply according to the present invention described later, and particularly an embossment is imparted to the toilet paper, strong rigidity is felt, and softness is hardly felt.
On the other hand, in the toilet paper according to the present embodiment, the basis weight of each ply is 10.5 g/m² or more and 12.5 g/m² or less. The basis weight of each ply is preferably 10.6 g/m² or more and less than 12.4 g/m², and more preferably 10.7 g/m² or more and 12.3 g/m² or less. If the basis weight of each ply is within this range, sufficient difficulty in tearing and favorable touch can be obtained when the above 3-ply or 4-ply product is used. In addition, water-disintegrability is easily exhibited. Note that the basis weight according to the present invention is measured by the basis weight measuring method of JIS P 8124 (1998).
On the other hand, the toilet paper according to the present invention needs to be made from softwood kraft pulp in which constituent main fibers, that is, 50% by mass or more of the constituent fibers are oxygen-pulped and non-chlorine-bleached. The toilet paper according to the present invention is preferably made from softwood kraft pulp in which 80% by mass or more the constituent fibers are oxygen-pulped and non-chlorine-bleached, and particularly preferably softwood kraft pulp in which substantially 100% by mass of the constituent fibers without considering impurities and the like are oxygen-pulped and non-chlorine-bleached. More specifically, this softwood kraft pulp is also called NOKP, and is manufactured by continuously oxygen-pulping fibers in a continuous pulping pot, and particularly is not bleached with a chlorine-based bleaching agent thereafter. Here, kraft pulp (KP) used for a toilet paper includes a bleached one and an unbleached one, and an unbleached one contains a large amount of lignin. The softwood kraft pulp according to the present invention has not been bleached with a chlorine-based bleaching agent, but has been oxygen-pulped (oxygen-delignified). Therefore, about half of the content of lignin has been removed from the softwood kraft pulp. Note that the chlorine-based bleaching agent means not only chlorine but also chlorine dioxide and sodium hypochlorite. Therefore, ECF pulp is not the above softwood kraft pulp according to the present invention.
The toilet paper according to the present invention contains 50% by mass or more, preferably 80 to 100% by mass or more of softwood kraft pulp that has not been bleached with a chlorine-based bleaching agent but has been delignified by oxygen-pulping. In other words, the toilet paper is manufactured by using the softwood kraft pulp as a main fiber raw material, particularly as a whole fiber raw material. Therefore, the toilet paper provides a security feeling to a human body during use, and is environmentally friendly. Note that particularly a toilet paper containing 50% by mass or more of the softwood kraft pulp is light brown, is likely to give a visual impression of a natural product that has not been chemically treated, and gives a soft impression. Therefore, the toilet paper provides a large security feeling to a purchaser thereof.
Meanwhile, since the content of lignin has been reduced to about half of that before oxygen-pulping by the delignification treatment by oxygen-pulping. Therefore, the toilet paper exhibits softness more easily than a toilet paper containing pulp that has not been delignified at all as a raw material, and easily acquires a sufficient strength. In addition, the content of hardwood kraft pulp that is likely to reduce water-disintegrability can be at least less than 50% by mass, and particularly 0% by mass. The toilet paper easily exhibits favorable water-disintegrability, and hardly generates paper dust.
In addition, since lignin is not hydrophilic, softwood kraft pulp that contains lignin and has been oxygen-pulped and non-chlorine-bleached has a low fiber swelling property and a weak interfiber bond. Therefore, fibers are sparse, and water-disintegrability is favorable. Furthermore, softwood kraft pulp is derived from softwood, and therefore has a longer fiber length than hardwood-derived pulp. Therefore, softwood kraft pulp hardly generates paper dust, and has an excellent cushioning property in combination with lignin's action of preventing fibers from being dense.
A fiber component other than oxygen-pulped and non-chlorine-bleached softwood kraft pulp is not necessarily limited. However, it is desirable that oxygen-pulped and non-chlorine-bleached hardwood kraft pulp is used because the oxygen-pulped and non-chlorine-bleached hardwood kraft pulp has a light brown appearance and provides a security feeling that bleaching with a chlorine-based bleaching agent has not been performed. Virgin pulp or used paper pulp other than the oxygen-pulped and non-chlorine-bleached hardwood kraft pulp may be used. In a step of regenerating pulp from used paper, fibers in used paper pulp tend to be finer than pulp fibers before regeneration, and due to such a nature of the fibers, the fibers easily become dense without increasing a paper thickness, and paper strength easily increases. Meanwhile, if an excessive amount of used paper pulp is blended, texture such as flexibility is reduced. Therefore, in consideration of the characteristics of used paper pulp, the blending ratio thereof only needs to be set within a range of 0 to less than 20% by mass. Note that the type of used paper pulp is not necessarily limited. Used paper pulp made from milk carton used paper or high-quality used paper can be used.
The toilet paper according to the present invention can be a toilet paper that provides an excellent thick feeling, has excellent water-disintegrability, has sufficient softness, hardly generates paper dust, provides a security feeling to a human body during use, and is environmentally friendly by containing 50 to 100% by mass of oxygen-pulped and non-chlorine-bleached softwood kraft pulp, having a basis weight of 10.5 to 12.5 g/m² per ply, and being formed into a multi-ply product such as a 3-ply or 4-ply product.
On the other hand, it is desirable that the toilet paper according to the present invention is a non-moisturizer-applied paper to which a moisturizer has not been externally applied substantially. The moisturizer as an external additive according to the present invention is a polyol, examples of which include at least glycerin, diglycerin, propylene glycol, 1,3-butylene glycol, and polyethylene glycol. However, inclusion of the above component is not denied as long as the content of the above component is so small that an influence thereof is at a level not being worthy of a moisturizing toilet paper. The toilet paper according to the present invention provides an excellent security feeling to a human body. When a moisturizer is applied to the toilet paper, stickiness and moist feeling peculiar to the moisturizer are felt, and therefore the above security feeling to a human body is reduced.
On the other hand, the toilet paper according to the present invention contains a softener that determines softness and paper strength of a base paper itself, the softener being internally added during papermaking. The softener contained in the toilet paper according to the present invention is a cationic fatty acid amide-based softener. The cationic fatty acid amide-based softener does not reduce an effect due to inclusion of lignin, and acts to coat surfaces of the fibers. Even if the toilet paper contains a large amount of pulp containing lignin, the toilet paper has a smooth surface, remarkably reduces a stiff feeling, and enhances a fullness. As a specific example of the cationic fatty acid amide-based softener, it is desirable that the cationic fatty acid amide-based softener is a reaction product between an amide-based compound obtained by a reaction between a polyalkylene polyamine and a monocarboxylic acid, and epihalohydrin. An effect is exhibited if this cationic fatty acid amide-based softener is used. Note that when the reaction product between an amide-based compound obtained by a reaction between a polyalkylene polyamine and a monocarboxylic acid, and epihalohydrin is internally added, the product is preferably mixed with an emulsifier having an alkyl group and/or an alkenyl group having 4 to 20 carbon atoms, and water and added. The content of the cationic fatty acid amide-based softener is not necessarily limited. However, when a fixing ratio is 50 to 60%, the amount thereof added during manufacturing only needs to be 0.5 to 4.0 kg/pulp t.
Furthermore, it is desirable that a softening moisturizer is internally added to the toilet paper according to the present invention. It is desirable that the content thereof is 0.2 to 2.0 kg/pulp t. By inclusion of the softening moisturizer, suppleness is improved. A particularly preferable softening moisturizer is a reaction product obtained by causing a compound obtained by adding an alkylene oxide having 2 to 4 carbon atoms to active hydrogen of a polyalkyleneimine having a weight average molecular weight of 500 to 10,000 to react with a higher fatty acid having 12 to 24 carbon atoms and/or an ester compound of a higher fatty acid having 12 to 24 carbon atoms. By inclusion of this softening moisturizer, softness is further improved.
In the toilet paper according to the present invention, each ply has a paper thickness of 80 to 100 µm, and the toilet paper has an overall paper thickness of 320 to 400 µm. When the paper thicknesses of each ply and the toilet paper are within this range, an excellent fullness, excellent softness, and a reassuring thick feeling can be provided. The paper thickness of the toilet paper is obtained by sufficiently (usually for about eight hours) subjecting a test piece to humidity control under conditions of JIS P 8111 (1998), and then measuring the paper thickness in a 1-ply state using a dial thickness gauge (thickness measuring instrument) "PEACOCK G type" (manufactured by Ozaki MFG. Co. Ltd.) under the same conditions. Specifically, it is confirmed that there is no rubbish, dust, or the like between a plunger and a measuring table, the plunger is placed on the measuring table, a scale of the dial thickness gauge is moved to adjust a zero point, then the plunger is raised, a sample is placed on a test table, the plunger is lowered slowly, and the current gauge is read. When the toilet paper is embossed, measurement is performed such that one constituent concave (convex) is necessarily within a range of the measuring table. Note that when there are concaves with different depths, measurement is performed such that the deepest concave is located within the range of the measuring table. During this measurement, the plunger is only placed and not pressed. A terminal of the plunger is made of metal, and a circular plane thereof with a diameter of 10 mm strikes perpendicularly to a paper plane, and a load is about 70 gf when the paper thickness is measured. Note that the paper thickness is an average of values obtained by performing the measurement 10 times. Here, when the paper thickness is measured, crushing of an embossment (concave) is assumed, but the paper thickness according to the present invention is a value measured including such crushing, and such crushing may be ignored. In the present paper thickness measurement, a difference in paper thickness caused by crushing of a concave can be ignored.
It is desirable that the toilet paper according to the present invention contains pulp fibers that is not unbeaten. It is desirable that the beating degree of a papermaking raw material during manufacturing is not necessarily limited, but it is desirable to beat the papermaking raw material such that a down width of the Canadian standard freeness is 20cc to 50cc. This down width is much smaller than the beating width of a general papermaking raw material. In this case, the Canadian standard freeness of the papermaking raw material is approximately 600 cc or more. By preventing the pulp fibers from being beaten too much and preventing the pulp fibers from being unbeaten in this way, the softener is easily fixed to surfaces of the fibers when the softener is internally added so as to be contained, and the fibers are moderately entangled with each other. A small desired paper thickness is easily obtained, excellent softness is achieved, and a favorable fullness is provided. Moreover, paper dust is extremely unlikely to be generated. The paper thickness can be further adjusted with a crepe ratio.
The toilet paper according to the present invention may be embossed. An emboss pattern thereof is not necessarily limited. An embossment can be an appropriate emboss pattern such as a micro-embossment, a dot-shaped embossment, or a design embossment. However, it is desirable that the emboss pattern according to the present invention is imparted in a ply stacked state called a single embossment.
A suitable emboss pattern according to the present invention has a concave area of 1.0 to 2.5 mm², a density of 5.0 to 50 pieces/cm², and an embossment depth of 0.05 to 0.5 mm. Softness of the toilet paper is improved, and softness in a rolled state like a toilet roll is increased, which makes a consumer easily feel that the toilet paper is soft when the consumer holds the toilet paper in his/her hand. In particular, as illustrated in Fig. 1, on the entire surface of paper, square concaves 31 (Fig. 1A) in each of which a bottom surface is diagonal L4 × diagonal L4 = 1.0 to 1.5 × 1.0 to 1.5 mm or substantially square concaves 32 (Fig. 1B) obtained by extending corners of the squares diagonally outward are arranged in a lattice with a center spacing L5 of 4.5 to 5.5 mm and an arrangement angle of 45° with respect to a width direction, and there is a valley line portion 33 extending from each of the corners of the concave between the concave 31 (32) and the concave 31 (32). Note that it is desirable that the valley line portion 33 is gradually gently formed in a cross-sectional arch such that the valley line portion 33 is deepest in the corners of the concave 31 (32) and shallowest in the middle between the concaves. This emboss pattern is excellent in softness and a stool wiping property.
The depth of embossing is measured by a one-shot 3D measurement macroscope VR-3200 manufactured by KEYENCE CORPORATION or its equivalent machine, and image analysis software "VR-H1A" or its equivalent software. Measurement is performed under conditions of a magnification of 12 times and a visual field area of 24 mm × 18 mm. However, the magnification and the visual field area can be appropriately changed depending on the size of an embossment (concave). A specific measurement procedure will be described with reference to Fig. 2. Using the above software, an embossment depth (measurement cross-sectional curve) profile at a line segment Q1 crossing the longest portion of a peripheral edge of one embossment (concave) 40 in an image portion (X portion in the drawing) illustrated by a plane viewpoint is obtained. A "contour curve Q2" of an image portion (Y portion in the drawing) illustrated by a cross-sectional viewpoint is obtained by removing a component of surface roughness having a shorter wavelength than λc: 800 µm (provided that λc is the "filter that defines a boundary between a roughness component and a waviness component" described in JIS-B0601 "3.1.1.2") from the cross-sectional curve of this embossment depth profile with a low pass filter. In this contour curve Q2, a minimum value sandwiched between two concave edge points P1 and P2 that are protruding upward and have the strongest bend and concave edge points P1 and P2 is determined and defined as a minimum depth value Min. Furthermore, an average value of the depth values of the concave edge points P1 and P2 is defined as a maximum depth value Max. In this way, embossment depth = maximum value Max - minimum value Min. In addition, a distance (length) between the concave edge points P1 and P2 on the X-Y plane is defined as the length of the longest portion. The above two concave edge points P1 and P2 that are protruding upward and have the strongest bend are visually selected. Note that for the selection, a contour E in the image illustrated by a plane viewpoint of the embossment (concave) 40 during the measurement may be referred to. Similarly, the depth of an embossment (concave) is measured for the shortest portion in a direction perpendicular to the longest portion, and a larger value is adopted as the depth of the embossment (concave). The above measurement is performed for any 10 embossments on a surface of the toilet paper, and an average value thereof is defined as a final embossment depth.
Note that also for the area of each concave of the emboss pattern, a contour of an embossment concave is visually confirmed from a 3D image obtained by measurement with a one-shot 3D measurement macroscope VR-3200 or its equivalent machine and image analysis software "VR-H1A" or its equivalent software, and an area inside the contour is measured. The above measurement is performed for any 10 embossments on a surface of the toilet paper, and an average value thereof is defined as a final area of the embossment concave.
The toilet paper according to the present invention has water-disintegrability of 10 seconds or less, which is very fast. This is because 50% by mass or more, preferably 80% by mass or more, particularly 100% by mass of the constituent fibers is softwood kraft pulp containing lignin, and the fibers are easily loosened. If water-disintegrability is within 10 seconds, a risk of clogging a pipe is remarkably reduced when the toilet paper is discarded into running water in a flush toilet or the like. This water-disintegrability (easiness of loosening) is measured according to JIS P 4501 (1993). In a test for easiness of loosening, a 300 mL beaker containing 300 mL of water (water temperature 20 ± 5°C) is placed on a magnetic stirrer, and the rotation speed of a rotor is adjusted to 600 ± 10 revolutions/minute. A test piece of a 100 ± 2 mm square is put into the beaker, and a stopwatch is pressed. The rotation speed of the rotor once drops to about 500 revolutions due to a resistance of the test piece, and rises as the test piece is loosened. When this rotation speed recovers to 540 revolutions, the stopwatch is stopped, and the time is measured in units of one second. A result of easiness of loosening is expressed by an average of results of five tests. The rotor has a disk shape having a diameter of 35 mm and a thickness of 12 mm.
It is desirable that the toilet paper according to the present invention has a longitudinal dry tensile strength of 500 cN/25 mm or more and 1200 cN/25 mm or less, more preferably 600 cN/25 mm or more and 1000 cN/25 mm or less. It is desirable that the toilet paper according to the present invention has a lateral dry tensile strength of 200 cN/25 mm or more and 450 cN/25 mm or less, more preferably 200 cN/25 mm or more and 350 cN/25 mm or less. If the dry tensile strength is within this range, the toilet paper is sufficiently durable for use.
Note that the longitudinal direction of paper is also referred to as MD (Machine Direction) and is a flow direction during papermaking. The lateral direction of paper is also referred to as CD (Cross Direction), and is a direction perpendicular to a flow direction (MD) during papermaking. The dry tensile strength according to the present invention is a value measured based on JIS P 8113 (2006), and is measured as follows. As a test piece, a tissue paper cut into a size of about 25 mm (± 0.5 mm) (width) × about 150 mm (length) in both MD and CD is used. The test piece is measured in a state of multiple plies. As a tester, a load cell tensile tester TG-200N manufactured by Minebea Co., Ltd. and its equivalent machine are used. Note that a grip interval is set to 100 mm, and a tensile speed is set to 100 mm/min. The measurement is performed by tightening both ends of the test piece to a grip of the tester, applying a tensile load to the paper piece in an up-down direction, and reading an indicated value (a digital value when the value is indicated by the digital value) when the paper breaks. Five sets of samples are prepared in each of MD and CD, and each sample is measured five times. An average of the measured values is defined as a dry tensile strength in each of the directions.
It is desirable that the toilet paper according to the present invention has a wet tensile strength in MD of 50 cN/25 mm or more and 100 cN/25 mm or less. It is desirable that the toilet paper according to the present invention has a wet tensile strength in CD of 15 cN/25 mm or more and 70 cN/25 mm or less. The wet tensile strength is a value measured based on JIS P 8135 (1998), and is measured as follows. As a test piece, a tissue paper cut into a size of about 25 mm (± 0.5 mm) (width) × about 150 mm (length) in both MD and CD is used. A multi-ply tissue paper is measured in a state of multiple plies. As a tester, a load cell tensile tester TG-200N manufactured by Minebea Co., Ltd. and its equivalent machine are used. Note that a grip interval is set to 100 mm, and a tensile speed is set to 50 mm/min. The test piece used has been cured for 10 minutes in a dryer at 105°C. The measurement is performed by tightening both ends of the test piece to a grip of the tester, then horizontally imparting water to a central portion of the test piece with a width of about 10 mm using a flat brush containing water, immediately thereafter applying a tensile load to the paper piece in an up-down direction, and reading an indicated value (digital value) when the paper breaks. Five sets of samples are prepared in each of MD and CD, and each sample is measured five times. An average of the measured values is defined as a wet tensile strength in each of the directions. Wet tensile strength was also measured in a stack of a plurality of sheets according to the number of plies of a product.
It is desirable that the toilet paper according to the present invention has an MMD value of 7.5 or more and 11.0 or less, which is an indicator indicating a surface property. When the MMD is less than 7.5, the surface is too smooth, and a wiping property deteriorates. When the MMD exceeds 11.0, the toilet paper may have poor touch and may be unsuitable for use as a toilet paper. Note that in measuring MMD, while a contact surface of a friction element is brought into contact with a surface of a measurement sample to which a tension of 20 g/cm is applied in a predetermined direction at a contact pressure of 25 g, the measurement sample is moved by 2 cm in substantially the same direction as the direction in which the tension is applied at a speed of 0.1 cm/s, and a friction coefficient at this time is measured using a friction sense tester KES-SE (manufactured by Kato Tech Co., Ltd.) or its equivalent machine. A value obtained by dividing the friction coefficient by a friction distance (moving distance = 2 cm) is MMD. The friction element is formed by adjoining 20 piano wires P each having a diameter of 0.5 mm, and has a contact surface formed such that the length and the width are both 10 mm. On the contact surface, a unit bulging portion having a tip formed with 20 piano wires P (radius of curvature: 0.25 mm) is formed.
It is desirable that the toilet paper of the present embodiment has Softness of 2.0 cN/100 mm or more and 3.5 cN/100 mm or less. Softness is one of indicators of softness, in which paper is softer as the paper has a lower value of Softness. A tissue paper or a toilet paper having Softness of 3.5 cN/100mm or less is evaluated to be soft. Softness is a value measured based on a handle-o-meter method according to the JIS L 1096 E method (1990). However, a test piece has a size of 100 mm × 100 mm, and a clearance is set to 5 mm. A 1-ply product is measured five times in each of MD and CD, and an average of the total 10 values is defined as Softness. Softness is unitless, but may be expressed in units of cN/100 mm considering the size of a test piece.
In the toilet paper according to the present embodiment, the dry tensile strength and the wet tensile strength can be adjusted without using a paper strength agent such as a dry paper strength enhancer or a wet paper strength enhancer. In particular, it is desirable that the toilet paper contains no paper strength agent from a viewpoint of a user's security feeling. By blending a large amount (80% by mass or more, particularly 100% by mass) of softwood kraft pulp having a long fiber length in the toilet paper according to the present invention, entanglement between the fibers is ensured, and sufficient strength for use can be achieved even if the toilet paper contains no paper strength agent. Moreover, the toilet paper contains lignin, and therefore also has excellent water-disintegrability. That is, sufficient strength can be ensured without using a paper strength agent, and excellent water-disintegrability can be further achieved.
Note that it is desirable that the toilet paper of the present embodiment does not use a dry paper strength enhancer or a wet paper strength enhancer as described above, but the toilet paper may use the dry paper strength enhancer or the wet paper strength enhancer as necessary as long as water-disintegrability is not impaired. Examples of the dry paper strength enhancer here include starch, polyacrylamide, and carboxymethyl cellulose (CMC) or salt thereof such as sodium carboxymethyl cellulose, calcium carboxymethyl cellulose and zinc carboxymethyl cellulose.
Examples of the wet paper strength enhancer include a polyamide polyamine epichlorohydrin resin, a urea resin, an acid colloid/melamine resin, heat-crosslinkable coating PAM, TS-20 manufactured by Seiko PMC Corporation, a polymer aldehyde-functional compound such as glioxylated polyacrylamide and cationic glioxylated polyacrylamide, a copolymer of an acrylamide monomer modified with a divalent aldehyde of glyoxal and another copolymerizable unsaturated monomer, and dialdehyde starch.
On the other hand, the toilet paper of the present embodiment may have a sheet-like shape. However, as illustrated in Fig. 3, the toilet paper is suitably in a form of a toilet roll obtained by winding a belt-shaped toilet paper 10 around a paper tube (also referred to as a tube core) 20 into a roll shape.
It is desirable that the toilet roll according to the present invention has a winding diameter L2 (diameter) of 110 to 115 mm. The winding diameter of the toilet roll is defined as 120 mm or less in JIS P 4501, and a holder for setting a general toilet roll is created based on this 120 mm. The toilet roll of the present invention has a winding diameter of 110 to 115 mm, and has a size that can be sufficiently set in a general holder. Here, the winding diameter is a value measured using a diameter rule manufactured by Muratec KDS Corporation or its equivalent machine. An average of measured values at three different locations in a width direction is used as a measured value. Note that an average value for five rolls is used as an average value for products in the same manufacturing lot.
Meanwhile, it is desirable that the toilet roll has a winding length of 20 to 40m and a winding density of 0.20 to 0.30 m/cm² at this time. The winding density here is a value calculated by winding length (m)/actual cross-sectional area. The actual cross-sectional area is a value calculated by {(winding diameter/2) × (winding diameter/2) × π- (paper tube outer diameter/2) × (paper tube outer diameter/2) × π} (unit: cm²). That is, the actual cross-sectional area is an area obtained by subtracting the area of the paper tube on an opening end side from the area of an end surface. In the above roll form, when the toilet paper according to the present invention has a winding density of 0.20 to 0.28 m/cm², softness is remarkably felt when the roll is held in the hand on a peripheral surface thereof. Note it is desirable that a paper tube outer diameter (paper tube diameter) L3 is 35 to 45 mmϕ, which is similar to a general size.
It is desirable that the toilet paper of the present invention has a roll winding tightness of 1.8 to 3.0 mm. A "handy compression tester KES-G5" manufactured by Kato Tech Co., Ltd. is used to measure the roll winding tightness (mm) (T0 - TM). A toilet roll TR is placed horizontally on a horizontal pedestal made of a steel plate such that a central axis of the toilet roll TR is horizontal. A steel plate terminal having a circular plane with a compression area of 2 cm² is brought into contact with the center of an upper surface of an outer periphery of a roll trunk. With this contacted state as a zero point, the steel plate terminal is moved vertically downward at a speed of 10 mm/min from the zero point to compress the toilet roll. (T0 - TM) (mm) is defined as a roll winding tightness (mm), in which T0 (mm) represents the amount of pushing when a compression load is 0.5 gf/cm², and TM (mm) represents the amount of pushing when the compression load is 50 gf/cm². The larger the roll winding tightness (mm), the larger a pushing depth at the time of pushing at a maximum load of 50 gf/cm², which indicates that the paper is fluffy. That is, this corresponds to a fullness. Note that the above winding length and winding density can sufficiently provide the winding tightness.
Furthermore, it is desirable that the toilet roll of the present invention has a compression work amount (WC) of 3.5 to 5.5 gf·cm/cm². The compression work amount (WC) is a work amount from a time point when a steel plate terminal is brought into contact with a roll at 0.5 gf/cm² to a time point of pushing at a maximum load of 50 gf/cm². The larger the compression work amount (WC), the weaker a repulsive force at an initial stage of pushing. Therefore, at a moment when the roll is grabbed, the roll is felt to be soft. Thereafter, when the compression load is raised to 50 gf/cm² at which the roll is usually grabbed, the roll can be evaluated to be soft and fluffy.
The toilet paper according to the present invention contains oxygen-pulped and non-chlorine-bleached softwood kraft pulp containing lignin and having a long fiber length in an amount of 50% by mass or more of fibers, in which a bond between the fibers is moderately weak. Therefore, when the toilet paper is formed into the above roll form, the toilet paper has an excellent cushioning property, and softness is easily felt when the toilet paper is held in the hand as described above.
Hereinafter, the effect of the toilet paper according to the present invention will be further described with reference to Examples.

Examples

Next, for Reference Example, Examples, and Comparative Examples relating to the toilet paper of the present invention, sensory evaluation was performed on "softness", "fullness", "thick feeling", "tear and strength during use", and "how small the paper dust amount during use is". The structure of the toilet roll and the physical properties and composition of the toilet paper according to each example are illustrated in Table 1 below. Reference Example has a general fiber structure equivalent to a product using pulp bleached with chlorine-based bleaching agent, which is also called a bleached product, and contains a larger amount of LBKP, which is hardwood pulp, than NBKP, which is softwood pulp. Comparative Examples 5 and 6 are commercially available products each containing unbleached pulp. In Comparative Examples 1 to 3, the basis weight and the paper thickness are particularly higher than those in Examples. An embossment of each of Reference Example, Examples, and Comparative Examples 1 to 4 had the pattern illustrated in Fig. 1.

For the sensory evaluation, 18 subjects actually used the rolled toilet paper according to each example, and performed relative evaluation on each item of "softness", "fullness", "thick feeling", "tear and strength during use", and "how small the paper dust amount during use is" based on Comparative Example 6 (conventional product). In the evaluation, Comparative Example 3 was evaluated as 4 points (median), and scoring was performed from 7 points for a good evaluation to 1 point for a poor evaluation with a difference for one point up or down, and an average value thereof was calculated for judgement.

[Table 1]

			Reference Example	Example 1	Example 2	Comparative Example 1	Comparative Example 2	Comparative Example 3	Comparative Example 4	Comparative Example 5	Comparative Example 6	Comparative Example 7
Bleached/Unbleached			Bleached	Unbleached	Unbleached	Unbleached	Unbleached	Unbleached	Unbleached	Unbleached	Unbleached	Unbleached
Pulp	NUKP	%	0	0	0	0	0	0	0	-	-	-
	NOKP		0	100	100	100	100	100	100	-	-	-
	NBKP		35	0	0	0	0	0	0	-	-	-
	LUKP		0	0	0	0	0	0	0	-	-	-
	LOKP		0	0	0	0	0	0	0	-	-	-
	LBKP		65	0	0	0	0	0	0	-	-	-
Freeness			430 cc	640 cc	640 cc	Unbeaten	Unbeaten	Unbeaten	Unbeaten	-	-	-
Softener	Fatty acid-based softener	kg/T	0.85	0.85	0.85	1.4	1.4	1.4	1.4	-	-	-
Softener	Softening moisturizer	kg/T	0.5	0.5	0.5	0.5	0.5	0.5	0.5	-	-	-
Crepe ratio		%	20	18	18	20	20	20	20	-	-	-
Basis weight		g/m²	15.0	11.0	12.0	15.0	12.9	15.0	15.6	15.4	15.5	15.1
Paper thickness	Single ply	µm	100	86	91	138	135	135	142	92	105	96
Paper thickness	Total plies	µm	400	343	364	553	540	405	365	367	315	287
Number of plies		Sheet	4	4	4	4	4	3	3	4	3	3
Dry tensile strength	MD	cN/25mm	720	767	897	739	477	565	758	763	579	1397
Dry tensile strength	CD	cN/25mm	320	261	298	376	243	305	386	393	461	364
Softness		cN/100 mm	2.1	2.6	3.2	2.6	1.9	2.2	2.7	3.6	3.5	4.9
MMD		1/100	7.0	9.5	9.5	9.1	9.0	9.0	8.8	12.1	13.5	15.3
Water-disintegrability		Second	17	8.5	8.5	8	8	8	8	108	49	Unmeasurable (large)
Winding length		m	23.0	26	26	23.0	23.0	30.6	30.6	24.0	22.9	32.0
Winding diameter		mm	117	117	117	116	117	117	117	104	95	104
Paper tube diameter Outer diameter		mm	41	41	41	41	41	41	41	43	45	40
Winding density		m/cm2	0.24	0.27	0.28	0.25	0.24	0.24	0.24	0.34	0.31	0.33
Roll density		g/cm3	0.146	0.121	0.133	0.149	0.126	0.146	0.152	0.210	0.194	0.200
Roll width		mm	104	104	104	103	104	104	104	108	95	102
Perforation pitch		mm	114	114	114	116	117	114	114	130	105	110
Embossment		-	Present	Present	Present	Present	Present	Present	Present	Absent	Absent	Absent
Winding tightness (roll)	0.5-50gf/cm2	mm	1.60	2.60	2.22	2.11	2.06	2.12	2.12	0.64	0.54	0.52
WC	(Compression work amount)	gf·cm/cm2	3.16	5.25	4.49	4.23	4.39	4.19	4.29	1.09	0.96	0.97

Softness		1 to 7	6.3	6.7	6.5	6.2	6.4	6.4	6.1	4.2	4.0	4.4
Fullness		1 to 7	5.1	6.6	6.5	5.0	5.3	5.1	5.0	3.9	4.0	4.0
Thick feeling		1 to 7	4.9	4.5	4.5	6.8	6.6	4.9	4.3	4.3	4.0	3.7
Tear and strength during use		1 to 7	6.2	5.8	5.9	6.7	6.1	6.1	6.4	3.7	4.0	3.7
How small paper dust amount during use is		1 to 7	4.7	4.5	4.5	2.9	3.5	3.4	3.0	4.0	4.0	3.5

Examples of the present invention show much better sensory evaluation results than Comparative Examples 5 to 7, which are conventional unbleached products, in "softness", "fullness", "thick feeling", "tear and strength during use", and "how small the paper dust amount during use is". In addition, Examples of the present invention show sensory evaluation results equivalent to or higher than the bleached product (Reference Example) in "softness", "fullness", "thick feeling", "tear and strength during use", and "how small the paper dust amount during use is". That is, each of Examples of the present invention uses softwood pulp having a long fiber length as 100% by mass raw material pulp, and has high freeness, but obtained sensory evaluation results equivalent to or higher than the bleached product (Reference Example) using a papermaking raw material containing a large amount of LBKP with a short fiber length and having a low freeness. That is, each of Examples of the present invention has quality equivalent to the bleached product (Reference Example) while providing a security feeling provided by the unbleached product.
Furthermore, when Example 1 is compared with Comparative Examples 1 to 4, it is evaluated that paper dust is much less likely to be generated in Example 1.
In the form of the toilet roll, in Examples of the present invention, the compression work amount was larger than those in Reference Example and Comparative Examples, and more softness was felt when the toilet paper in the roll form was held in the hand.
As described above, the toilet paper according to the present invention provides a thick feeling that can make a user reassured during use thereof in a shower toilet, has sufficient softness, does not easily generate paper dust, has excellent water-disintegrability, and provides a security feeling to a human body during use thereof.

Reference Signs List

1: Toilet roll
10: Toilet paper
20: Paper tube (tube core)
L1: Winding diameter (diameter) of toilet roll
L2: Diameter of tube core of toilet roll
L3: Width of toilet roll
31, 32: Concave
33: Valley line portion

Claims

A 3-ply or 4-ply toilet paper, comprising:
oxygen-pulped and non-chlorine-bleached softwood kraft pulp in an amount of 50 to 100% by mass of fibers; and

a cationic fatty acid amide-based softener,

wherein each ply has a basis weight of 10.5 to 12.5 g/m² and a thickness of 80 to 100 µm, and

the toilet paper has an overall thickness of 320 to 400 µm and a water-disintegrability of 10 seconds or less.