TOILET PAPER

- Daio Paper Corporation

Provided is toilet paper which is excellent in thickness feeling and water disintegrability, has sufficient softness, gives a sense of security for human bodies during use, and is environmentally friendly. Toilet paper has three or four plies. The basis weight is 12.5 to 15.5 g/m2 per ply. 80 to 100 mass % of fiber is softwood kraft pulp that is subjected to oxygen pulping and is not bleached with chlorine. The toilet paper contains a cationic fatty acid amide-based softener, and has a paper thickness of 120 to 150 μm per ply, a paper thickness of 400 to 600 μm as a whole of the toilet paper, and a water disintegrability of 10 seconds or less.

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Description
TECHNICAL FIELD

The present invention relates to toilet paper.

BACKGROUND ART

With the spread of shower toilets, which are also called toilets with a washing function, toilet paper is also required to be suitable for use in shower toilets (Patent Literature 1 below).

It is desirable that toilet paper suitable for shower toilets be a product with multiple plies such as three plies or four plies, which gives a sense of security when used by a consumer.

Toilet paper is generally produced from a fiber raw material obtained by mixing hardwood-derived pulp having a short fiber length and softwood-derived pulp having a long fiber length, and principally, common toilet paper contains a large amount of hardwood-derived pulp that likely improves softness and surface properties.

In addition, in order to enhance the whiteness, pulp, which is a fiber raw material, is bleached with a chlorine-based bleaching chemical such as chlorine, chlorine dioxide or sodium hypochlorite, and consumers giving great importance to a sense of security for human bodies and environmental consideration desire environmentally friendly products in which pulp free of a chlorine-based bleaching chemical is used as a raw material.

CITATION LIST Patent Literature Patent Literature 1: JP 2011-153387 A SUMMARY OF INVENTION Technical Problem

However, in pulp that has not been bleached with a chlorine-based bleaching chemical, a large amount of lignin remains, and fiber is hard, and toilet paper obtained using the pulp as a main fiber raw material is likely to give a feeling of hardness or surface roughness.

On the other hand, it is known that the strength of the paper is decreased by increasing the blending amount of hardwood pulp for easily giving a feeling of softness, but when the blending amount of hardwood pulp is increased, water disintegrability is likely to deteriorate. In the case of multi-ply products, water disintegrability is likely to deteriorate in particular, and therefore when the blending amount of hardwood pulp is increased, the toilet paper may be unsuitable for use in shower toilets.

Accordingly, a main object of the present invention is to provide toilet paper which gives a thickness feeling providing security when used in a shower toilet, has sufficient softness, is excellent in water disintegrability, and gives a sense of security for human bodies during use.

Solution to Problem

The first means for achieving the above-described object is toilet paper having three or four plies, in which

80 to 100 mass % of fiber is softwood kraft pulp that is subjected to oxygen pulping and is not bleached with chlorine,

the toilet paper containing a cationic fatty acid amide-based softener, and

having a basis weight of 12.5 to 16.0 g/m2 per ply,

a paper thickness of 120 to 150 μm per ply,

a paper thickness of 400 to 600 μm as a whole of the toilet paper, and

a water disintegrability of 10 seconds or less.

Advantageous Effects of Invention

Thus, according to the present invention, there is provided toilet paper which gives a thickness feeling providing security when used in a shower toilet, has sufficient softness, is excellent in water disintegrability, and gives a sense of security for human bodies during use.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view of embosses according to an embodiment of the present invention.

FIG. 2 is a schematic diagram for illustrating a procedure for measuring an emboss depth 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

The toilet paper according to an embodiment has three plies or four plies. That is, three or four sheets are stacked. When the toilet paper has multiple plies including more than two plies, such as three plies or four plies, the overall paper thickness is large while each ply is thin, and the toilet paper hardly breaks and gives a sense of security while it is likely to feel “soft” in particular.

If the toilet paper has two plies, it is difficult to develop a thickness feeling, and the toilet paper lacks a sense of security when wiping is performed while a large amount of water is absorbed after use of a shower toilet. When the toilet paper has five or more plies, it is difficult to feel the softness during cleaning of the skin even when each ply is thinned. In addition, when the number of plies is five or more while the basis weight and the paper thickness per ply are set according to the present invention as described later, and in particular, embosses are applied, the rigid feeling is intensified, and it is difficult to feel the softness.

On the other hand, the toilet paper according to this embodiment has a basis weight of 12.5 g/m2 or more and 16.2 g/m2 or less per ply. If the basis weight of one ply is within this range, when the toilet paper has three or four plies, sufficient resistance to breakage and a good feel against the skin can be obtained, and water disintegrability is easily developed.

On the other hand, in the toilet paper according to the present invention, 80 to 100 mass %, particularly 100 mass %, of the constituent fiber is softwood kraft pulp which is subjected to oxygen pulping and is not bleached with chlorine. More specifically, this softwood kraft pulp, which is also called NOKP, is produced by oxygen pulping continuously performed in a continuous pulping kettle, and is not subsequently bleached with a chlorine-based bleaching chemical in particular. Here, kraft pulp (KP) used for toilet paper includes bleached and unbleached kraft pulp, and unbleached kraft pulp contains a large amount of lignin. The softwood kraft pulp used in the present invention is not bleached with a chlorine-based bleaching chemical, but is subjected to oxygen pulping (removal lignin with oxygen), so that about half of the lignin is removed. The chlorine-based bleaching chemical includes not only chlorine but also chlorine dioxide and sodium hypochlorite. Thus, the ECF pulp is not the softwood kraft pulp used in the present invention.

The toilet paper according to the present invention contains 80 to 100 mass % of softwood kraft pulp which is not bleached with a chlorine-based bleaching chemical and is subjected to lignin removal treatment by oxygen pulping. That is, the toilet paper is produced using such softwood kraft pulp as a main fiber raw material, particularly as all of fiber raw materials, and therefore gives a sense of security for human bodies during use and it is environmentally friendly. In particular, toilet paper containing 80 to 100 mass % of such softwood kraft pulp is light brown and thus apt to look like a natural product which has not been chemically treated. Also, such toilet paper gives an impression of being soft. Therefore, a purchaser has a great sense of security.

On the other hand, since lignin removal treatment by oxygen pulping reduces the amount of lignin to about half of that before the oxygen pulping, it is easier to develop softness and obtain high strength as compared to a case where pulp which is not subjected to lignin removal treatment at all is used as a raw material. In addition, since the amount of hardwood kraft pulp, whose water disintegrability is apt to decrease, is at most less than 20 mass %, particularly 0 mass %, it is easy to improve water disintegrability.

In addition, since lignin is not hydrophilic, lignin-containing softwood kraft pulp which is subjected to oxygen pulping and is not bleached with chlorine has low fiber swellability and weak interfiber bonding. Thus, the fibers become less dense, so that water disintegrability is improved. Further, an excellent cushioning property is obtained because softwood kraft pulp is derived from softwood and thus has a longer fiber length than that of pulp derived from hardwood and because lignin has an action of preventing densification of the fibers.

The toilet paper according to the present invention contains 80 to 100 mass % of the softwood kraft pulp and has a basis weight of 12.5 to 16.0 g/m2 per ply. The basis weight per ply is more preferably 12.7 to 15.8 g/m2. The basis weight according to the present invention is based on the basis weight measurement method of JIS P 8124 (1998). When the toilet paper contains 80 to 100 mass % of the softwood kraft pulp, and has a slightly low basis weight per ply of 12.5 to 15.5 g/m2, and multiple plies such as three plies or four plies, the toilet paper is excellent in thickness feeling and water disintegrability, easily develops softness, gives a sense of security for human bodies during use, and is environmentally friendly. Here, other pulp fibers forming the toilet paper according to the present invention are not necessarily limited. The pulp fiber may be virgin pulp or used paper pulp. In the step of regenerating pulp from used paper, the used paper pulp tends to have finer fiber than the pulp fiber before the regeneration, and due to such a property of the fiber, the fiber is easily densified to enhance the paper strength without increasing the paper thickness. On the other hand, if used paper pulp is blended in an excessive amount, texture properties such as flexibility deteriorate. Thus, in consideration of the characteristics of used paper pulp, the blending ratio may be set within the range of 0 to less than 20 mass %. The type of used paper pulp is not necessarily limited, and used paper pulp with milk carton used paper or high-quality used paper is particularly desirable. Used paper pulp contains a large amount of hardwood kraft pulp (LBKP) derived from a raw material, so that it is easy to develop paper strength.

On the other hand, it is desirable that the toilet paper according to the present invention be moisturizer-non-coated toilet paper substantially not coated with a moisturizer. The moisturizer as an external additive according to the present invention is a polyol, and includes at least glycerin, diglycerin, propylene glycol, 1,3-butylene glycol and polyethylene glycol. However, the toilet paper may contain the above-described components as long as their effect is not worthy of giving the toilet paper a moisture-retaining property. The toilet paper according to the present invention is excellent in sense of security for human bodies, and when a moisturizer is applied, a sticky feeling and a moist feeling peculiar to the moisturizer arise, so that the sense of security for human bodies decreases.

On the other hand, a softener or a softening moisturizer, that determines the softness and paper strength of the base paper itself, is internally added during papermaking to the toilet paper according to the present invention. The softener contained in the toilet paper according to the present invention is a cationic fatty acid amide-based softener. The toilet paper according to the present invention preferably contains this cationic fatty acid amide-based softener. The cationic fatty acid amide-based softener does not undergo a decrease in effect due to the presence of lignin, and acts to coat the fiber surface. Accordingly, even when pulp containing lignin is blended at a high ratio, the surface is smooth, the stiff feeling markedly decreases, and the fullness is enhanced. As a specific example of the cationic fatty acid amide-based softener, a reaction product of epihalohydrin with an amide-based compound obtained by reaction of a polyalkylene polyamine with a monocarboxylic acid is desirable. The effect is exhibited when this cationic fatty acid amide-based softener is used. In internal addition of a reaction product of epihalohydrin with an amide-based compound obtained by reaction of a polyalkylene polyamine with a monocarboxylic acid, it is preferable that the reaction product is mixed with an emulsifier having an alkyl group and/or an alkylene group with 4 to 20 carbon atoms, and water, followed by addition of the mixture. The content of the cationic fatty acid amide-based softener is not necessarily limited, and when the fixing rate is 50 to 60%, the amount added during production may be 0.5 to 4.0 kg/ton of pulp.

Further, it is desirable that a softening moisturizer be internally added to the toilet paper according to the present invention. It is desirable that the content be 0.2 to 2.0 kg/ton of pulp. Presence of a softening moisturizer improves flexibility. The softening moisturizer is particularly preferably a reaction product obtained by reacting a higher fatty acid with 12 to 24 carbon atoms and/or an ester compound of a higher fatty acid with 12 to 24 carbon atoms with a compound obtained by adding an alkylene oxide with 2 to 4 carbon atoms to active hydrogen of a polyalkyleneimine with a weight average molecular weight of 500 to 10,000. Presence of the softening moisturizer further improves softness.

Here, the toilet paper according to the present invention may be embossed. The embossed pattern is not necessarily limited. The embosses can be applied in an appropriate embossed pattern such as microembosses, dot-shaped embosses or design embosses. However, it is desirable that the embossed pattern according to the present invention be that of embosses applied in a ply-laminated state, which are called single embosses.

A suitable embossed 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 emboss depth of 0.05 to 0.5 mm. The softness as toilet paper is improved, and the softness in a rolled state like that of a toilet roll is enhanced, so that the toilet paper is likely to feel soft when a consumer holds it in the hand. In particular, as shown in FIG. 1, concaves 31 having a square bottom surface with diagonal line L4×diagonal line L4=1.0 to 1.5×1.0 to 1.5 mm (FIG. 1A) or substantially square concaves 32 in which the four corners of the square extend diagonally outward (FIG. 1B) are arranged in a grid pattern with a center spacing L5 of 4.5 to 5.5 mm and an arrangement angle of 45° with respect to the width direction, over the entire plane of paper, and valley line portions 33 extending from the four corners of the concave are present between the concave 31 (32) and the concave 31 (32). It is desirable that the valley line portion 33 be gradually gently arranged in an arch shape at a cross-section so as to be deepest at the four corners of the concave 31 (32) and shallowest at the middle point between the concaves. This embossed pattern is excellent in softness and stool wiping property.

The emboss depth is measured by a one-shot 3D measurement macroscope VR-3200 manufactured by KEYENCE CORPORATION or its equivalent, and the image analysis software “VR-H1A” or its equivalent software. The measurement is performed under the conditions of a magnification of 12 times and a viewing area of 24 mm×18 mm. However, the magnification and the viewing area can be appropriately changed depending on the size of the emboss (concave). The specific measurement procedure will be described with reference to FIG. 2. By use of the above-described software, an emboss depth (measured cross-section curve) profile at a line segment Q1 crossing the longest part of the peripheral edge of one emboss (concave) 40 in the image part (X part in the figure) shown in plan view. In the “contour curve Q2” of the image part (Y part in the figure) shown in sectional view, which is obtained by removing the component of surface roughness at a wavelength shorter than λc: 800 μm (λc is a “filter for defining a boundary between a roughness component and a wave component” as described in JIS-B0601 “3.1.1.2”) from the cross-sectional curve of the emboss depth profile, a minimum value of two concave edge points P1 and P2 projected upward and most sharply curved and a region sandwiched between the concave edge points P1 and P2 is determined, and taken as a minimum depth value Min. Further, the average of the depth values of the concave edge points P1 and P2 is taken as a maximum depth value Max. In this way, the emboss depth is determined from: emboss depth=maximum value Max−minimum value Min. Further, the distance (length) of the concave edge points P1 and P2 on the X-Y plane is taken as a length of the longest part. In addition, the two concave edge points P1 and P2 projected and most sharply curved are visually selected. In the selection, reference may be made to a contour E in the image in plan view of the emboss (concave) 40 during the measurement. Similarly, the emboss (concave) depth is measured for the shortest part in a direction perpendicular to the longest part, and the value of a larger depth is adopted as the emboss (concave) depth. The above measurement is performed for any 10 embosses on the surface of the toilet paper, and an average thereof is taken as the final emboss depth.

For the areas of individual concaves of the emboss pattern, the contour of the emboss concave is visually confirmed from a 3D image obtained by performing measurement with a one-shot 3D measurement macroscope VR-3200 manufactured by KEYENCE CORPORATION or its equivalent, and the image analysis software “VR-H1A” or its equivalent software, and the area inside the contour is measured. The measurement is performed for any 10 embosses on the surface of the toilet paper, and an average thereof is taken as the final emboss area.

On the other hand, the toilet paper according to the present invention has a paper thickness of 120 to 150 μm per ply, and a paper thickness of 400 to 600 μm as a whole of the toilet paper. When the paper thickness is in this range, the softness is improved. The method for measuring the paper thickness of toilet paper includes sufficiently humidity-conditioning a test piece under the conditions of JIS P 8111 (1998) (usually about 8 hours), and then performing measurement in a one-ply state by use of 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 dust, dirt or the like is not present between a plunger and a measuring table, the plunger is placed on the measuring table, the scale on the dial thickness gauge is moved to set to the zero point, the plunger is then raised to place a sample on a sample table, the plunger is slowly moved down, and the gauge at this time is read. When the toilet paper is embossed, it is ensured that one concave (convex) is within the range of the measuring table. When there are concaves having different depths, it is ensured that a concave having the deepest depth is within the above-mentioned range. During the measurement, the plunger is merely placed, and is not pressed. The terminal of the plunger is made of metal. A circular plane with a diameter of 10 mm perpendicularly hits the plane of paper, and the load during the measurement the paper thickness is about 70 gf. The paper thickness is an average of values obtained by performing measurement 10 times. Here, during measurement of the paper thickness, there may be collapsed embosses (concaves), but the paper thickness in the present invention is a value obtained by measuring the values including those of such collapsed embosses, and such collapse may be ignored. In the measurement of the paper thickness, a paper thickness difference caused by collapse of concaves can be ignored.

In addition, the toilet paper according to the present invention is very rapidly hydrolyzed with the water disintegrability being 10 seconds or less. This is because 80 mass % or more, particularly 100 mass %, of the constituent fiber is softwood kraft pulp containing lignin, so that the fiber is easily loosened. When the water disintegrability is 10 seconds or less, the risk of clogging pipes at the time of disposition by running water in a flush toilet or the like dramatically decreases. The water disintegrability (easiness of loosening) is measured in accordance with JIS P 4501 (1993). For the test on 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 the rotor is adjusted to 600±10 rotations/minute. A square test piece 100±2 mm on a side is put into the beaker, and the stopwatch is started. The rotation speed of the rotor once decreases to about 500 rotations due to the resistance of the test piece, and the rotation speed increases as the test piece is loosened. The time when the rotation speed recovers to 540 rotations, the stopwatch is stopped, and the time is measured on a second-by-second basis. The test is conducted five times, and an average thereof is taken as a result of ease of loosening. The rotor has a disk shape with a diameter of 35 mm and a thickness of 12 mm.

It is desirable that the toilet paper according to the present invention be one in which the Canadian standard freshness of the papermaking raw material is 650 cc or more. When the Canadian standard freshness of the papermaking raw material is 650 cc or more, the pulp fiber is hardly beaten, or fiber from an unbeaten raw material, and therefore toilet paper further excellent in water disintegrability is easily obtained.

Here, it is desirable that the toilet paper according to the present invention have a dry tensile strength of 400 cN/25 mm or more and 900 cN/25 mm or less in a longitudinal direction. It is desirable that the dry tensile strength in a lateral direction be 200 cN/25 mm or more and 450 cN/25 mm or less. The toilet paper can be sufficiently used as long as the dry tensile strength is within the above-mentioned range.

The longitudinal direction of the paper, which is also called a MD direction, is a flow direction during papermaking. The lateral direction of the paper, which is also called a CD direction, is a direction orthogonal to the flow direction (MD direction) during papermaking. The dry tensile strength according to the present invention is a value measured in accordance with JIS P 8113 (2006). The measurement is performed in the following manner. As a test piece, one obtained by cutting the paper to approximately a width of 25 mm (±0.5 mm)×length of 150 mm in both longitudinal and lateral directions, is used. The test piece is measured as it has a plurality of plies. As a testing machine, a load cell tensile testing machine TG-200N manufactured by Minebea Inc. or a machine equivalent thereto is used. The grip interval is set to 100 mm, and the tensile speed is set to 100 mm/min. The measurement is performed in accordance with a procedure in which the test piece is tightly fastened at both ends to a grip of the testing machine, a tensile load is applied to the paper piece in an up-down direction, and an indicated value (digital value) is read at the time when the paper breaks. For each of the longitudinal direction and the lateral direction, five samples are prepared, measurement is performed five times, and an average of the measured values is taken as a dry tensile strength in each of the directions. For the product, the dry tensile strength was measured with a plurality of sheets stacked to coincide with the number of plies of the product. For the base paper, the dry tensile strength was measured with a plurality of sheets stacked to coincide with the number of plies of the product.

In addition, it is desirable that the toilet paper according to the present invention have a wet tensile strength of 50 cN/25 mm or more and 100 cN/25 mm or less in a longitudinal direction. It is desirable that the wet tensile strength in a lateral direction be 25 cN/25 mm or more and 50 cN/25 mm or less. The wet tensile strength is a value measured in accordance with JIS P 8135 (1998). The measurement is performed in the following manner. A test piece cut to approximately a width of 25 mm (±0.5 mm)×length of 150 mm in both longitudinal and lateral directions. When having a plurality of plies, the tissue paper is measured as it has a plurality of plies. As a testing machine, a load cell tensile testing machine TG-200N manufactured by Minebea Inc. or a machine equivalent thereto is used. The grip interval is set to 100 mm, and the tensile speed is set to 50 mm/min. As the test piece, one cured with a dryer at 105° C. for 10 minutes is used. The measurement is performed in accordance with a procedure in which the test piece is tightly fastened at both ends to a grip of the testing machine, water is then horizontally applied to the central part of the test piece with a width of about 10 mm, a tensile load is then immediately applied to the paper piece in an up-down direction, and an indicated value (digital value) is read at the time when the paper breaks. For each of the longitudinal direction and the lateral direction, five samples are prepared, measurement is performed five times, and an average of the measured values is taken as a wet tensile strength in each of the directions. For the wet tensile strength, the wet tensile strength was measured with a plurality of sheets stacked to coincide with the number of plies of the product.

It is desirable that the toilet paper according to the present invention be one in which the MMD value that is an index showing surface properties is 7.5 or more and 9.5 or less. If MMD is less than 7.5, the surface is excessively slippery, so that the wiping property deteriorates. If MMD is more than 9.5, the toilet paper may be poor in texture, and thus unsuitable for its use purpose. In the measurement of MMD, the surface of a friction element is brought into contact under a contact pressure of 25 g with the surface of a measurement sample given a tension of 20 g/cm in a predetermined direction, and is simultaneously moved by 2 cm at a speed of 0.1 cm/s in a direction substantially identical to the direction in which the tension is given, and the coefficient of friction at this time is measured by use of a frictional feeling tester KES-SE (manufactured by KATO TECH CO., LTD.) or an equivalent machine. The value obtained by dividing the coefficient of friction by the friction distance (movement distance=2 cm) is MMD. The friction element is formed by mutually adjacent 20 piano wires P each having a diameter of 0.5 mm, and has a contact surface formed so as to have a length of 10 mm and a width of 10 mm. The contact surface is provided with a unit bulge portion having a tip formed by 20 piano wires P (curvature radius is 0.25 mm).

It is desirable that the toilet paper of this embodiment preferably have a softness of 1.8 cN/100 mm or more and 3.5 cN/100 mm or less. The softness is one of the indices of softness, and the lower the value of the softness, the softer the product. The tissue paper or the toilet paper is considered sufficiently soft when the value of the softness is 1.0 cN/100 mm or less. The softness is a value measured on the basis of a handle-o-meter method conforming to the JIS L 1096E method (1990). The size of the test piece is 100 mm×100 mm, and the clearance is 5 mm. In each of the longitudinal direction and the lateral direction, measurement is performed five times per ply. An average of a total of 10 measurements is taken as the softness. The softness has no unit, but may be expressed in a unit of cN/100 mm with consideration given to the size of the test piece.

In the toilet paper of the present embodiment, the dry tensile strength and the wet tensile strength can be adjusted without use of a dry paper strength enhancer or a wet paper strength enhancer. It is desirable that in particular, the toilet paper be free of the paper strength enhancer from the viewpoint of a sense of security for users. The toilet paper according to the present invention contains softwood kraft pulp having a large fiber length in a large amount of 80 mass % or more, particularly 100 mass %, and therefore even when a paper strength enhancer is not contained, entanglement of fibers can be secured to obtain strength sufficient for use. In addition, the toilet paper contains lignin, and is therefore excellent in water disintegrability. That is, sufficient strength can be secured without use of a paper strength enhancer, and water disintegrability can be improved.

In the toilet paper of this embodiment, it is desirable to prevent use of a dry paper strength enhancer or a wet paper strength enhancer as described above, but such an agent may be used as necessary as long as the water disintegrability is not impaired. Examples of the dry paper strength enhancer as used herein include starch, polyacrylamide, CMC (carboxymethyl cellulose), and sodium carboxymethyl cellulose, calcium carboxymethyl cellulose and zinc carboxymethyl cellulose which are salts of CMC.

Examples of the wetting paper strength enhancer include polyamide polyamine epichlorohydrin resins, urea resins, acid colloid/melamine resins, heat-crosslinkable coating PAM, TS-20 manufactured by Seiko PMC Corporation, polymer-aldehyde functional compounds such as glyoxylated polyacrylamide and cationic glyoxylated polyacrylamide, copolymers of acrylamide monomers obtained by modifying glyoxal with divalent aldehyde and other copolymerizable unsaturated monomers, and dialdehyde starch.

On the other hand, the toilet paper of this embodiment is suitable for formation of a toilet roll in which a strip-shaped toilet paper 10 is wound around a paper tube (also referred to as a tube core) 20 in a roll shape as shown in FIG. 3.

It is desirable that the toilet roll according to the present invention have 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 prepared on the basis that the winding diameter is 120 mm. The toilet roll of the present invention, which has a winding diameter of 110 to 115 mm, is sized to be thoroughly settable in a general holder. Here, the winding diameter is a value measured by use of a diameter rule manufactured by MURATEC-KDS Corp. or an equivalent machine. The measured value is an average of measurements made at three different positions in a width direction. The average in products of the same production lot is an average for five rolls.

On the other hand, it is desirable that the winding length of the toilet roll be 20 to 40 m, and here it is desirable that the winding density be 0.20 to 0.30 m/cm2. The winding density here is a value calculated from the formula: winding length (m)÷actual cross-sectional area. The actual cross-sectional area is calculated from the formula: {(roll diameter/2)×(roll diameter/2)×π−(paper tube outer diameter/2)×(paper tube outer diameter/2)×π} (unit; cm2). That is, actual cross-sectional area is an area obtained by subtracting the lateral surface area of the opening of the paper tube from the area of the end surface. When having a winding density of 0.20 to 0.28 m/cm2 in the above-described roll form, the toilet paper according to the present invention feels markedly soft when the peripheral surface of the roll is held in a hand. It is desirable that the outer diameter of the paper tube (paper tube diameter) L3 be 35 to 45 mmφ, similarly to a general size.

In addition, in the toilet paper of the present invention, it is desirable that the winding hardness of the roll be 1.8 to 2.2 mm. “Handy Compression Tester KES-G5” manufactured by KATO TECH CO., LTD. is used for measuring the winding hardness (mm) (T0-TM) of the roll. The toilet roll TR is horizontally placed on a horizontal pedestal formed of a steel plate in such a manner that the central axis of the toilet paper is horizontal, and a steel plate terminal having a circular plane with a compression area of 2 cm2 is brought into contact with the center of the upper surface of the outer periphery of the roll trunk. This contact state is taken as a zero point, and the steel plate terminal is moved vertically downward from such a zero point at a speed of 10 mm/min to compress the toilet roll. The amount of pressing at a compressive load of 0.5 gf/cm2 is T0 (mm), the amount of pressing at a compressive load of 50 gf/cm2 is TM (mm), and (T0-TM) (mm) is the winding hardness of the roll. When the winding hardness (mm) of the roll increases, the pressing depth at the time of pressing the roll to 50 gf/cm2 increases, and the roll has fluffy paper quality. That is, the winding hardness of the roll corresponds to a fullness. When the winding length and the winding density are as described above, such a winding hardness can be thoroughly obtained.

Further, it is desirable that the toilet roll of the present invention have a compression work amount (WC) of 3.6 to 4.6 gf·cm/cm2. The compression work amount (WC) is a work amount when the steel plate terminal is brought into contact with the roll at 0.5 gf/cm2 and then pressed to 50 gf/cm2. When the compression work amount (WC) increases, the repulsive force at the initial stage of pressing decreases, so that the roll feels soft at the instance when the roll is grasped, and when the roll is subsequently pressed to a large depth under a compression load of 50 gf/cm2 at which the roll is normally held, the roll can be evaluated as being soft and fluffy in quality.

In the toilet paper according to the present invention, 80 to 100 mass % of fiber is softwood kraft pulp which is subjected to oxygen pulping and is not bleached with chlorine and which contains lignin and has a large fiber length, and interfiber bonding is weak, so that in the above-described roll form, the toilet paper is excellent in cushioning property, and likely to feel soft when held in a hand as described above.

Hereinafter, the effects of the toilet paper according to the present invention will be further described with reference to examples.

EXAMPLES

Sensory evaluation was performed on “softness”, “fullness”, “thickness feeling” and “breakage and strength during use” for examples of the toilet paper of the present invention and comparative examples.

The configuration of the toilet roll and the physical properties and composition of the toilet paper according to each example are shown in Table 1 below.

For the sensory evaluation, 18 subjects actually used the rolled toilet paper of each example, and relative evaluation was performed on the items of “softness”, “fullness”, “thickness feeling” and “tear strength during use” with respect to Comparative Example 3 (conventional product). In the evaluation, Comparative Example 3 was given a score of four points (median), and scores were given at intervals of one point where the highest score was set to seven points and the lowest score was set to one point. An average of the scores was calculated.

TABLE 1 Compar- Compar- Compar- Compar- Compar- ative ative ative ative ative Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- ple 1 ple 2 ple 3 ple 4 ple 1 ple 2 ple 3 ple 4 ple 5 Bleached/ Un- Un- Un- Un- Bleached Un- Un- Un- Un- unbleached bleached bleached bleached bleached bleached bleached bleached bleached Pulp NUKP % 0 0 0 0 0 — — — — NOKP 100 100 100 100 0 — — — — NBKP 0 0 0 0 35 — — — — LUKP 0 0 0 0 0 — — — — LOKP 0 0 0 0 0 — — — — LBKP 0 0 0 0 65 — — — — Freeness Un- Un- Un- Un- 430 cc — — — — beaten beaten beaten beaten Softener Fatty acid- kg/T 1.4 1.4 1.4 1.4 0.85 — — — — based softener Soft kg/T 0.5 0.5 0.5 0.5 0.5 — — — — moisturizer Crepe ratio % 20 20 20 20 20 — — — — Weight per g/m2 15.0 12.9 15.0 15.6 15.0 15.4 15.5 15.0 15.1 square meter Paper One ply μm 138 135 135 142 100 92 105 96 96 thickness All plies μm 553 540 405 385 400 367 315 287 287 Number of Sheets 4 4 3 3 4 4 3 3 3 plies Dry tensile Longitudinal cN/ 739 477 565 758 720 763 579 612 1397 strength 25 mm Dry tensile Lateral cN/ 376 243 305 336 320 393 461 385 364 strength 25 mm Softness cN/ 2.6 1.9 2.2 2.7 2.1 3.6 3.5 3.3 4.9 100 mm MMD 1/100 9.1 9.0 9.0 8.8 7.0 12.1 13.5 11.3 15.3 Hydrolyzability Seconds 8 8 8 8 17 108 49 53 Measure- ment impossible (large) Winding length m 23.0 23.0 30.6 30.6 23.0 24.0 22.9 10.5 32.0 Winding diameter mm 116 117 117 117 117 104 95 68 104 Paper core tube mm 41 41 41 41 41 43 45 41 40 (outer diameter) Winding density m/cm2 0.25 0.24 0.24 0.24 0.24 0.34 0.31 0.34 0.33 Roll width mm 103 104 104 104 104 108 95 108 102 Stich pitch mm 116 117 114 114 114 130 105 140 110 Embossing — Done Done Done Done Done Not Not Not Not done done done done Winding hardness (roll) mm 2.11 2.06 2.12 2.12 1.60 0.64 0.54 0.66 0.52 0.5-50 gf/cm2 WC gf · 4.23 4.39 4.19 4.29 3.16 1.09 0.96 1.02 0.97 (compression work amount) cm/cm2 Softness 1 to 7 6 6 6 6 6 4 4 4 3 Fullness 1 to 7 5 5 5 6 5 4 4 4 3 Thickness feeling 1 to 7 7 7 6 5 5 4 4 4 4 Breakage and strength 1 to 7 7 6 6 6 6 3 4 4 7 during use

Examples according to the present invention showed excellent results in the sensory evaluation. In addition, for water disintegrability, markedly excellent results were obtained. In addition, in comparison with Comparative Example 1 which is comparable in winding density to examples, superior measurement results were obtained in terms of winding hardness and compression work amount (WC) when the toilet paper is in the form of a roll. Further, regarding the strength, measurement results were obtained which shows that strength sufficient to prevent breakage during use was secured.

Thus, the toilet paper according to the present invention gives a thickness feeling providing security when used in a shower toilet, has sufficient softness, is excellent in water disintegrability, and gives a sense of security for human bodies during use.

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

1. Toilet paper having three or four plies, comprising:

a softwood kraft pulp that is subjected to oxygen pulping and is not bleached with chlorine, and accounts for 80 to 100 mass % of fiber, and
a cationic fatty acid amide-based softener,
wherein the toilet paper has a basis weight of 12.5 to 15.5 g/m2 per ply,
a paper thickness of 120 to 150 μm per ply,
a paper thickness of 400 to 600 μm as a whole of the toilet paper, and
a water disintegrability of 10 seconds or less.
Patent History
Publication number: 20210401242
Type: Application
Filed: Nov 22, 2019
Publication Date: Dec 30, 2021
Applicant: Daio Paper Corporation (Ehime)
Inventors: Shuta YASUI (Shizuoka), Minoru IWASAKI (Shizuoka)
Application Number: 17/297,220
Classifications
International Classification: A47K 10/16 (20060101); D21H 27/30 (20060101); D21H 11/04 (20060101); D21H 17/07 (20060101);