Paper towels and paper towel products

Abstract

This invention provides a 3- or 4-layer paper towel that reduces the stickiness of the outer surface while ensuring necessary softness, and a method for manufacturing the same. The paper towel is a 3- or 4-layer paper towel, wherein each layer contains a water-based humectant exhibiting hygroscopic properties, and the content of the water-based humectant between each layer is in the range of 92.0% to 108.0% when the dry humectant content of the product is set to 100%.

Description

Technical Field

[0001] This invention relates to tissues, and more particularly to tissues coated with a moisturizing agent and tissue articles thereof. Background Technology

[0002] While two-ply paper towels are the mainstream, in recent years, the demand for multi-ply and thicker paper towels, such as three-ply and four-ply paper towels, has been increasing.

[0003] Such multi-layered tissues are mostly high-priced, premium products. These tissues require a certain level of "fluffiness," "smoothness of the surface," and "softness" corresponding to the number of layers.

[0004] Moreover, in the case of a multi-layered structure, if the weight per unit area of ​​each layer is increased, the paper thickness can be easily increased by the sum of the weights of each layer, thereby creating a "fluffy and fluffy feel".

[0005] However, when increasing the weight per unit area of ​​each layer in this way, it is important to show a “fluffy, fluffy feel” while ensuring softness and smoothness.

[0006] Regarding tissues, there are various types of tissues available on the market. In one category, there are tissues containing water-based moisturizers, which are called moisturizing tissues or lotion tissues.

[0007] To meet the needs of people who frequently blow their noses with tissues due to hay fever, colds, etc., traditional moisturizing tissues and lotion tissues have been redesigned to be soft and smooth, so that the skin will not turn red or hurt even after repeated use.

[0008] The way tissues are used varies from country to country. This is believed to be due to differences in lifestyle or culture.

[0009] In Japan, moisturizing tissues and facial cleansing tissues are mainly two-ply tissues, while in China, three-ply tissues are the mainstream.

[0010] Existing technical documents

[0011] Patent documents

[0012] Patent Document 1: Japanese Patent Application Publication No. 2018-171254 Summary of the Invention

[0013] The problem that the invention aims to solve

[0014] In the past, in the manufacture of three-layered moisturizing tissues or lotion tissues, moisturizer was applied only to the two outer layers, and no moisturizer was applied to the middle layer.

[0015] In the past, moisturizing tissues or lotion tissues, a certain amount of moisturizer was applied in order to make them feel soft to the user.

[0016] However, on the other hand, the application of a large amount of humectant can make the outer surface of the outer sheet feel sticky, so it is not preferred.

[0017] Therefore, the object of the present invention is to provide a 3- or 4-layer paper towel that reduces the stickiness of the outer surface while ensuring the necessary softness, and a method for manufacturing the same.

[0018] Methods for solving problems

[0019] The paper towel of the present invention, which solves the above-mentioned problems, is a paper towel with three or four layers, characterized in that,

[0020] Each layer contains a water-based humectant that exhibits hygroscopic properties.

[0021] Regarding the content of the water-based humectant between each layer, when the dry humectant content of the product is set to 100%, the dry humectant content of each layer is in the range of 92.0% to 108.0%.

[0022] Furthermore, the tissue product of the present invention is a tissue product formed by storing three or four layers of tissues in a storage body, characterized in that...

[0023] Each layer contains a water-based humectant that exhibits hygroscopic properties.

[0024] Regarding the content of the water-based humectant between each layer, when the dry humectant content of the product is set to 100%, the dry humectant content of each layer is in the range of 92.0% to 108.0%.

[0025] The effects of the invention

[0026] According to the present invention, it is possible to obtain 3- or 4-ply paper towels that reduce the stickiness of the outer surface while ensuring the necessary softness. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the method of applying the medicine solution.

[0028] Figure 2 This is an explanatory diagram of a rotary interlacing folding machine.

[0029] Figure 3 It is a summary diagram of the layered structure.

[0030] Figure 4 This is an explanatory diagram of a 3-layer implementation method.

[0031] Figure 5 This is an explanatory diagram of a 4-layer implementation method.

[0032] Figure 6 This is an explanatory diagram of a conventional 3-layer implementation.

[0033] Figure 7 This is an explanatory diagram of the conventionally assumed 4-layer implementation method.

[0034] Figure 8 It is a photo of an example of the application of the medicine.

[0035] Figure 9 These are photos of non-applied surfaces of the medication. Detailed Implementation

[0036] The present invention will be further described below while showing embodiments thereof.

[0037] It is a tissue with 3 or 4 layers.

[0038] Because it has three or four layers instead of two, it creates a "fluffy and fluffy feel".

[0039] Each layer is coated with a water-based moisturizer exhibiting hygroscopic properties (hereinafter sometimes referred to as "liquid," meaning the same thing), thus containing a moisturizer. As a water-based moisturizer exhibiting hygroscopic properties, a moisturizer with polyols as the main component, especially a moisturizer with glycerin as the main component (i.e., containing more than 50% by mass of glycerin, preferably more than 70% by mass of glycerin), can be used. Glycerin exhibits hygroscopic properties in addition to its moisturizing properties.

[0040] To improve surface properties, especially smoothness, liquid paraffin may be included. Additionally, depending on the requirements, 6.1% to 12.6% by mass of 1,3-propanediol may be included.

[0041] In addition to humectants such as glycerin, paper towels may also contain known additives. Examples of additives include humectant ingredients such as sorbitol, hydrophilic polymer gelling agents that improve the moisture retention of the paper towel, surfactants or softening agents, oily ingredients such as liquid paraffin that help to exhibit smoothness, and other emulsifiers, preservatives, and defoamers that improve the humectant's stabilizing and coating properties. Furthermore, the mixing amount of humectant ingredients and hydrophilic polymer gelling agents that improve moisture retention is set to a level that does not excessively affect the "fluffy feel," "softness," and "surface smoothness." Specifically, it can be set to 1.0% by mass or less, preferably 0.6% by mass or less, and more preferably 0.5% by mass or less.

[0042] In this embodiment, the basis weight of one layer of the paper towel is preferably 15.0 to 22.5 g / m³. 2The preferred concentration is 15.5–20.5 g / m³. 2 When the base weight of each layer is within this range, the "softness" and "loose and fluffy feel" become very apparent.

[0043] Because paper tends to become stiffer at higher basis weights and softer at lower basis weights, it is believed that basis weight has a significant impact on "softness". A "3- or 4-layer" basis weight can significantly impart a "fluffy and light feel". Furthermore, the basis weight is based on values ​​measured according to JIS P 8124 (1998).

[0044] The aforementioned water-based humectant is present in approximately equal amounts in each layer. That is, when the content of the product's drying humectant (solution) is set to 100%, the content of the drying humectant (solution) in each layer is in the range of 92.0% to 108.0%. Ideally, the content of the drying humectant (solution) in each layer should be in the range of 95.0% to 104.0%.

[0045] Figure 4 A three-layer (1R, 2R, 3R) implementation is shown. Figure 5 An implementation with four layers (1R, 2R, 3R, 4R) is shown. Figure 6 A conventional implementation with three layers (1R, 2R, 3R) is shown. Figure 7 A conventional implementation with 3 layers (1R, 2R, 3R) is shown.

[0046] Additionally, the coated surface F and the uncoated surface W of the moisturizer are shown. Since there is a significant concentration gradient of the moisturizer in the thickness direction from the coated surface F towards the uncoated surface W, this concentration gradient is illustrated in color.

[0047] As mentioned above, in traditional moisturizing tissues (also known as lotion tissues), a certain amount of moisturizer was applied to ensure a soft feel for the user. Therefore, in order to avoid... Figure 6 and Figure 7 The intermediate layer shown in the conventional implementation ( Figure 6 The middle is 2R. Figure 7 Applying a moisturizer to the outer sheet (2R and 3R) can lead to an overuse of the moisturizer, resulting in a sticky feel on the outer surface of the sheet, which is not preferable.

[0048] In contrast, the paper towel of this embodiment differs from conventional multi-layer paper towels in that it has a middle layer (intermediate sheet layer) Figure 4 The middle is 2R, Figure 5 Water-based moisturizers are also used in 2R and 3R models.

[0049] The advantage of this structure is that by including a water-based humectant in the intermediate layer (intermediate sheet), the intermediate layer (intermediate sheet) becomes soft, thereby making the entire laminate soft.

[0050] As a result, the amount of humectant contained in the outer sheet can be reduced, thereby eliminating or suppressing the stickiness caused by the humectant on the outer surface of the outer sheet (the exposed surface of the laminated sheet).

[0051] Furthermore, when the content of the drying and moisturizing agent (medicinal solution) of the product is set to 100%, as long as the content of the drying and moisturizing agent (medicinal solution) of each layer is within the above range, this advantage can be manifested substantially independently of the basis weight of each layer and the content of the moisturizing agent in each layer.

[0052] In order to make the intermediate layer (intermediate sheet) also contain water-based moisturizers, it can be done by applying a moisturizer directly to the intermediate layer in addition to the outer layer.

[0053] For example, when a humectant is applied to the outer layer of a laminated sheet, the humectant diffuses from the coated surface into the entire sheet over time. However, if external pressure, such as calendering, is applied to the outer layer of the laminated sheet, some of the humectant will transfer to adjacent sheets. However, when the amount of humectant applied is small, the amount of humectant transferred to adjacent sheets is also small.

[0054] On the other hand, when the amount of humectant applied is large, although the amount of humectant transferred to adjacent sheets increases, the transfer is still limited, and there is a clear difference in the humectant content between the outer sheet coated with humectant and the adjacent sheets.

[0055] Therefore, in order to ensure that the intermediate layer (intermediate sheet) also contains the moisturizer needed to ensure softness, a moisturizer needs to be applied directly to the intermediate layer in addition to the outer layer.

[0056] Conversely, when a large amount of humectant is applied to the outer sheet in order to transfer the humectant to the intermediate layer to ensure softness, a large amount of humectant will remain on the outer surface (exposed side) of the outer sheet, resulting in a sticky feeling.

[0057] However, by also applying the humectant directly to the intermediate layer (intermediate sheet), the amount of humectant applied to the outer surface (exposed surface) of the outer sheet can be reduced, thereby eliminating or suppressing the sticky feeling.

[0058] To impart softness to the paper towel, the sheet material is typically creased. In this embodiment, creasing is also preferred.

[0059] The optimal number of wrinkles is 38–54 wrinkles per cm.

[0060] The number of wrinkles (creases / cm) measured in one-shot 3D can be expressed as follows: draw a line shape in the MD direction, count the number of peaks with a peak-valley shape of 1.0 to 2.0 cm in the MD direction, and divide by the measured length in the MD direction to obtain the value.

[0061] When shape measurement is performed using one-shot 3D and the height profile on the XY plane is displayed on the screen, the height of the tissue surface is represented by a hue. The shape of the wrinkles in the height direction can be determined from the profile of the measured cross-section curve. Here, since wrinkles form peaks and valleys in a direction perpendicular to the MD direction by 90°, this value is obtained by counting the number of peaks with a peak-valley shape of 1.0–2.0 cm in the MD direction and dividing by the measured MD length. For one sample, the average of the measurements from 5 points is taken as this value.

[0062] The sharpness of the peak tip, "arithmetic mean curvature of the peak tip, Spc", is preferably 2.8 to 3.5 (1 / mm) (the larger the value, the sharper the small protrusions on the surface).

[0063] This creping process creates a difference in surface roughness between one side and the other side of the sheet paper.

[0064] When applying a humectant to the sheet base paper, it is preferable to apply the humectant to the surface with less unevenness caused by the wrinkling process.

[0065] That is, among different layers with surface roughness expressed as the size of the arithmetic mean height Sa based on ISO25178, it is preferable to apply a moisturizer to the surface with the smaller arithmetic mean height Sa.

[0066] Furthermore, if a moisturizer is applied to a surface with a small arithmetic mean height Sa, it will have a smooth feel and be soft because it is a surface with a small arithmetic mean height Sa and the moisturizer is present in sufficient quantity.

[0067] Because the outer layer contains a medicinal solution, when the laminated sheet is calendered after the humectant is applied, the paper is smoothed by the external pressure on the outer surface of the outer layer. The applied humectant spreads evenly on the surface, making the surface smooth and exhibiting further "surface smoothness".

[0068] Regarding the paper towels coated with a moisturizing agent in the embodiments, the arithmetic mean height Sa of the outer surface (especially the exposed surface of the laminated sheet) under non-pressure conditions is preferably 0.005 to 0.012 mm, and particularly preferably 0.006 to 0.008 mm. If this arithmetic mean height Sa is within this range, the surface is smooth and exhibits moderate unevenness, thus providing excellent wiping properties, for example, for lipstick, foundation, etc.

[0069] Here, "under non-pressurization" means that the measurement is performed in the generated ("unprocessed") state.

[0070] Conversely, if a humectant is applied to the uneven surface of the base paper layer caused by the wrinkling process, the humectant is also hygroscopic. Therefore, over time, the surface will absorb moisture and form large wrinkles, resulting in surface shrinkage and damaging the smoothness of the surface.

[0071] The arithmetic mean height Sa, as defined by ISO 25178, represents the average of the absolute values ​​of the height differences between points on the surface relative to the average surface of the defined area. A smaller value indicates a smaller absolute value of the height difference between points relative to the average surface, signifying a smoother surface; a larger value indicates a rougher surface.

[0072] Furthermore, for tissue products in which the tissue bundle is popped into the packaging, when measuring the arithmetic mean height Sa, the measurement surface of the sample taken out of the tissue bundle is set as the surface where the folded peak side is located (the arithmetic mean curvature Spc of the peak is also the same).

[0073] Regarding the paper towel of the embodiment, the arithmetic mean curvature (Spc) of the peaks of the outer surface under non-pressure conditions is preferably 2.8 to 3.5 (1 / mm). The arithmetic mean curvature of the peaks represents the arithmetic mean of the principal curvatures of the peaks in the defined region. The smaller the value, the more curved the point of contact with other objects; the larger the value, the sharper the point of contact with other objects.

[0074] Furthermore, in the sample obtained from the pop-up beam, the measurement surface is the surface where the folded peak side is located. When the arithmetic mean curvature (Spc) of the peak apex of the outer surface under no pressure is 2.8 to 3.5 (1 / mm), the surface feels smooth and has excellent wipeability for lipstick, foundation, etc.

[0075] In this manual, “arithmetic mean height Sa” and “arithmetic mean curvature of peak (Spc)” refer to values ​​measured using the “one-shot 3D shape measuring instrument VR-3200 (manufactured by KEYENCE Corporation)” (hereinafter also referred to as “3D microscope”) and similar products (non-contact 3D measuring instruments).

[0076] The "3D microscope" can measure shape using structured illumination from the projection section and based on the fringe projection image of the object projected into a monochrome C-MOS camera. In particular, it can use the obtained fringe projection image to measure the height, length, angle, volume, etc., of any part. The observation, measurement, and image analysis of images obtained through the "3D microscope" can be performed using software "VR-H2A" and equivalent software. Furthermore, the measurement conditions are set to a field of view of 24mm × 18mm and a magnification of 12x.

[0077] The specific measurement steps for the arithmetic mean height Sa and arithmetic mean curvature (Spc) of the outer surface under no pressure are as follows.

[0078] A sheet of paper towel (approximately 50mm x 50mm in the MD direction and CD direction) serving as the sample layer is placed on the measuring stage in the generated state, with the measuring instrument facing forward and the depth direction aligned with the MD direction. Furthermore, the test piece used in the measurement is a flat portion of the product.

[0079] The operating software (“VR-H2A”) displays three images of the sample surface: a main image (texture), a main image (height), and a 3D image. Next, the “texture” image, displayed by selecting “surface roughness” or similar settings in the software, is converted into a “height” image (an image represented by the intensity of hues differentiated by color along the height direction).

[0080] Next, measurements are performed using at least the maximum height (Sz), the arithmetic mean height Sa, and the arithmetic mean curvature of the peak (Spc) as measurement parameters. The measurement area is 3.0mm × 3.0mm. If using the aforementioned software, the measurement area can be set by selecting "Value Assignment" in "Adding Area". The embossed portion is excluded from the measurement area, and the measurement area is set so that the hue intensity within each measurement area on the screen appears approximately consistent when viewed visually.

[0081] Confirm the measured values ​​of the maximum height (Sz), arithmetic mean height Sa, and arithmetic mean curvature of the peak (Spc). If the maximum height (Sz) exceeds 0.1000 mm, discard the value and set another measurement range. Furthermore, the maximum height (Sz), arithmetic mean height Sa, and arithmetic mean curvature of the peak (Spc) are surface roughness parameters specified by ISO 25178. Additionally, to eliminate large undulations in the sheet material, measurements are performed with Gaussian correction applied to the filter, no S-filter, F-operation as a 2D curved surface, L-filter 0.8 mm, and end-processing enabled.

[0082] Within a 3.0 mm square area serving as the measurement range, the plane roughness measurements of "maximum height (Sz)," "arithmetic mean height (Sa)," and "arithmetic mean curvature of the peak (Spc)" are performed. The location is changed, and a total of five 3.0 mm square area plane roughness measurements are performed at these locations. The average value of these five measurements is taken as the measured value of the "maximum height (Sz)," "arithmetic mean height (Sa)," and "arithmetic mean curvature of the peak (Spc)" of the sample. The 3.0 mm square area serving as the measurement range is located in the central part of a 24 mm × 18 mm field of view where strain is minimal. Furthermore, the selection of each of the five measurement ranges and the measurement of "maximum height (Sz)," "arithmetic mean height (Sa)," and "arithmetic mean curvature of the peak (Spc)" can be performed simultaneously, or the measurement range Z can be changed.

[0083] The content of the humectant in each layer is 10.0% to 35.0%. It is particularly preferred to be 17.0% to 30.0%. If the content is too low, the softness will be insufficient. If the content is too high, in addition to causing a sticky feeling on the exposed surface, it will also easily lead to a reduction in paper strength.

[0084] The desired product is a three-layered tissue paper, with each layer having a basis weight of 15.0–22.5 g / m³. 2 The thickness of the three-layer paper is 140–270 μm, particularly preferably 176–230 μm. In such a multi-layer structure, the paper thickness has a particularly strong influence on the "softness" and "fluffiness". In the paper towel of this embodiment, if the paper thickness is within this range, the "softness", "fluffy feel", and "surface smoothness" become significant.

[0085] In the case of a four-layered paper towel, it is desirable that the basis weight of each layer is 15.0–22.5 g / m³. 2 The thickness of the 4-layer paper is 180–360 μm, and is particularly preferred to be 220–320 μm.

[0086] The paper thickness was measured under the same conditions using a dial-type thickness gauge, the "PEACOCK G type" (manufactured by Ozaki Corporation), after the test piece was fully conditioned according to JIS P 8111 (1998). Specifically, after ensuring there was no dirt or dust between the plunger and the measuring stage, the plunger was lowered onto the measuring stage, and the scale of the dial-type thickness gauge was moved to zero. Then, the plunger was raised, the test piece was placed on the measuring stage, and the plunger was slowly lowered. The thickness was read at this point. During measurement, care was taken to ensure that the terminal of the metal plunger (a circular flat surface with a diameter of 10 mm) was perpendicular to the paper surface. The load during the paper thickness measurement was approximately 70 gf. The paper thickness was the average of 10 measurements taken at different locations. For the test piece, a three-layer sheet was used, and measurements were taken avoiding creases and embossed areas.

[0087] The paper towel of this embodiment preferably has a drying strength of 220 to 420 cN / 25 mm in the longitudinal direction of 3 or 4 layers. When the longitudinal drying strength is within this range, the "softness", "fluffy feel" and "smoothness of the surface" become significant. In addition, it is within the range of sufficient strength for durability.

[0088] When using a three-layer sheet of paper with excessively high drying strength (i.e., fibers are tightly packed together in the longitudinal direction and compressed under high pressure), a sticky feeling is likely to occur on the exposed surface due to poor softness and the fact that the humectant does not penetrate between the fibers (as intended).

[0089] Furthermore, the drying strength in the lateral 3 or 4 layers is preferably 60 to 160 cN / 25 mm. If the lateral drying strength is within this range, the "softness," "fluffy texture," and "surface smoothness" become significant. Additionally, it falls within a range of sufficient strength for durability.

[0090] Furthermore, although uncertain, "transverse dry tensile strength" affects the overall "skin feel" sensory function, rather than individual functions such as "softness" or "fluffiness." When test subjects evaluated the quality of the paper towel using a comprehensive evaluation criterion like "skin feel" after free contact with the sample, rather than specific evaluation criteria such as "softness" or "fluffiness," it was found that the evaluation of "skin feel" was somewhat correlated with "transverse dry strength."

[0091] In addition, the wet paper strength of the paper towel in the transverse direction of the present embodiment is preferably 50 to 90 cN / 25 mm in 3 or 4 layers.

[0092] The ratio of transverse wet tensile strength to transverse dry tensile strength is preferably 0.62 to 0.76. Furthermore, this value is measured while maintaining a 3- or 4-layer state. By setting such a strength difference, the user will feel a sense of "firmness (strength and reassurance)" when using the paper, such as when blowing their nose, or in situations where the paper changes from dry to wet. Furthermore, it is difficult to perceive the change in paper strength during such use, which affects the perceived "smoothness" during use.

[0093] In addition, the longitudinal direction of the paper is also called the MD direction, which is the flow direction during papermaking. The transverse direction of the paper is also called the CD direction, which is perpendicular to the flow direction (MD direction) during papermaking.

[0094] Furthermore, the dry (tensile) strength of the paper towel in this embodiment is based on values ​​measured according to JIS P 8113, and is measured as follows: For the test piece, test pieces cut to approximately 25mm (±0.5mm) wide × 150mm long are used in both the longitudinal and transverse directions. The paper towel is measured while maintaining multiple layers. For the testing machine, a force sensor tensile testing machine TG-200N manufactured by Minebea Co., Ltd., or a similar product, is used. The clamping interval is set to 100mm, and the tensile speed is set to 100mm / min. The measurement is performed as follows: the two ends of the test piece are secured to the clamps of the testing machine, a tensile load is applied to the paper sheet in the vertical direction, and the indication value (digital value) at which the paper breaks is read. Five sets of samples are prepared in both the longitudinal and transverse directions, and each is measured five times. The average of the measured values ​​is taken as the dry tensile strength in each direction. The sample adjustment is based on JIS P 8111 (1998).

[0095] Furthermore, the wet (tensile) strength of the paper towel in the embodiment was measured according to JIS P 8135 (1998), and was measured as follows: Regarding the test piece, test pieces cut to approximately 25mm (±0.5mm) wide × 150mm long were used in both the longitudinal and transverse directions. When the paper towel was multi-layered, the measurement was performed while maintaining the multi-layered state. Regarding the testing machine, a force sensor tensile testing machine TG-200N manufactured by Minebea Co., Ltd., or a similar product, was used. The clamping interval was set to 100mm, and the tensile speed was set to 50mm / min. For the test piece, a test piece cured in a dryer at 105°C for 10 minutes was used. The measurement was performed as follows: After securing both ends of the test piece to the clamps of the testing machine, water was applied horizontally to the center of the test piece with a water-containing flat pen at a width of approximately 10mm. Then, a tensile load was immediately applied to the paper sheet in the vertical direction, and the indicated value (digital value) at the point of paper breakage was read. Five sets of specimens were prepared in both the longitudinal and transverse directions, and each set was measured five times. The average of the measured values ​​was taken as the wet tensile strength in each direction.

[0096] The dry tensile strength and wet tensile strength can be adjusted by adding dry paper strength enhancers and wet paper strength enhancers to the pulp or wet paper. As dry paper strength enhancers, starch, polyacrylamide, CMC (carboxymethyl cellulose), or sodium carboxymethyl cellulose, calcium carboxymethyl cellulose, zinc carboxymethyl cellulose, etc., as their salts, can be used. As wet paper strength enhancers, polyamide-polyamine-epoxychlorohydrin resin, urea resin, acid colloid / melamine resin, thermally crosslinked coated PAM, etc., can be used. Furthermore, when adding dry paper strength enhancers internally, the addition amount relative to the pulp is approximately 1.0 kg / t of pulp or less. Additionally, the wet paper strength enhancer is preferably a cationic enhancer, and its addition amount relative to the pulp is approximately 5.0 to 20.0 kg / t of pulp.

[0097] The fiber material constituting the tissue paper is pulp fiber, preferably NBKP (coniferous kraft pulp) and LBKP (broadleaf kraft pulp) used for tissue paper. Waste paper pulp can also be blended, but since waste paper pulp is unlikely to exhibit "softness," a composition consisting solely of virgin NBKP and LBKP is extremely preferred. As a blending ratio, the mass ratio is NBKP:LBKP = 25:75 to 40:60. Within this range, the paper strength and "fluffy feel" required for blowing one's nose can be felt, and "softness" and "smoothness" can be significantly perceived.

[0098] The compression work for a total of 12 layers (3 layers, 4 groups) or 12 layers (4 layers, 3 groups) is preferably 1.85–2.50 gf·cm / cm. 2The preferred value is 2.18–2.35 gf·cm / cm. 2 The compression recovery is preferably 46.0-54.5%, and particularly preferably 48.0-53.0%.

[0099] [The manufacturing method of paper towels]

[0100] The paper towel of this embodiment and the product made by bundling and packaging the paper towel can be manufactured through the following manufacturing steps.

[0101] First, a single-layered tissue paper (sheet paper) with wrinkles, obtained using papermaking equipment, is wound up to form a primary blank roll. Next, this primary blank roll is placed in three (four in the case of four layers) laminating machines, also known as laminators, from which single-layer continuous sheets are fed and stacked into three (or four) layers. Then, appropriate slitting and winding are performed to produce a secondary blank roll.

[0102] Next, using this secondary blank roll, a stacked bundle is formed in a folding device such as a staggered folding machine.

[0103] Then, after the bundle of layers is cut into appropriate sizes, it is packaged in packaging, such as a paper box or a plastic bag, to make a paper towel product.

[0104] In the series of manufacturing processes of this tissue product, or between processes, a chemical application device is set up to apply a humectant (humectant solution) containing glycerin to the tissue base paper by external addition.

[0105] Specifically, the application of moisturizing solutions can be performed by assembling flexographic printing presses, gravure printing presses, roller transfer devices, spray coating devices, or other solution application devices on any of the laminators and staggered folding machines. Alternatively, these devices can be used as separate equipment from the laminators and staggered folding machines.

[0106] In the manufacture of the paper towel according to the embodiment, a humectant is applied to each layer of the base paper. The method of application can be appropriately selected.

[0107] As a method of applying moisturizing solutions, for example, it can be set as follows: Figure 1 In this way.

[0108] That is, three layers of sheet paper are fed out from the three-layer base paper roll 6, and the moisturizing liquid is picked up from the tray 8 by the gravure roller 9 and transferred to the metal roller 7A. While passing between the opposite metal roller 7B, the moisturizing agent is applied to the exposed surfaces of the outer and middle layers respectively.

[0109] In the subsequent position, a moisturizing solution is applied to the outer surface of the second outer layer of the other of the three-layer base paper sheets in the same manner.

[0110] Sheets coated with a moisturizing solution are wound up as blank roll 10.

[0111] Although moisturizing solutions can also be applied using a flexographic method, it has been confirmed that gravure application is more effective at creating a smooth surface compared to flexographic application.

[0112] Other coating methods are given as an example. For instance, if we take a three-layer example, the first coating unit and the second coating unit are configured such that the first pickup unit picks up the humectant and the first transfer roller that receives the humectant are paired, and the second pickup roller that picks up the humectant and the second transfer roller that receives the humectant are paired.

[0113] The first sheet of base paper, which is the outer layer of one side, and the second sheet of base paper, which is the inner layer of the other side, are fed in a stacked state between the first and second transfer rollers. A moisturizing agent is applied to the outer surface of the first sheet of base paper and the outer surface of the second sheet of base paper, respectively, to the first and second transfer rollers.

[0114] In the section following the initial coating, a third coating unit is provided, which pairs a third pick-up roller for picking up the humectant with a third transfer roller for receiving the humectant. The humectant is transferred and coated onto the outer surface of the third sheet base paper, which is the outer layer on the opposite side, using the third transfer roller.

[0115] In this case, in addition to positioning the third transfer roller opposite to a suitable support roller, the first or second transfer roller can be used as a support roller, and the third transfer roller can be used to transfer and apply the humectant to the outer surface of the third layer of sheet paper.

[0116] In adjusting the amount of coating applied to the object surface by each transfer roller, in addition to adjusting the amount of pickup by each pickup roller by, for example, the scraping degree of the squeegee, the amount of coating applied to the object surface by the transfer roller can also be adjusted by the speed difference between the pickup roller formed by the anilox roller and the transfer roller.

[0117] like Figure 2 As shown, a pair of stacked blank rolls 10A and 10B of laminated sheets coated with a moisturizing solution are formed into a folded product, for example, by a rotating staggered support 11.

[0118] The folding machine used for folding can be a device that uses folding plates, also known as multi-seat type, seat type, or folding plate type, or it can be a device that uses a pair of folding rollers, also known as rotary type, for folding.

[0119] In the implementation, a rotary staggered folding machine is preferred. In the case of multi-layered tissue products with three or more layers, the large number of layers makes it easy for the layers to shift. However, with a rotary staggered folding machine, because the tension applied to the continuous sheet is weaker than with other machines, layer shift is less likely to occur, and the folding quality is more easily improved. Therefore, especially during processing, the reduction in "fluffiness" is less likely.

[0120] Furthermore, it is preferable to calender the laminated sheets. Calendering the laminated sheets easily creates a thickness difference between the outer and middle layers. Additionally, especially when folding is performed using a rotary staggered folding machine, it is preferable to apply a moisturizing solution within the staggered folding machine. Furthermore, if the first calendering process is performed before applying the moisturizing solution and the second calendering process is performed after applying the moisturizing solution, it is easier to produce a tissue that has a noticeable "fluffy feel" and exhibits significantly noticeable "softness" and "smoothness."

[0121] Figure 3 An example of a folding configuration of laminated sheets is shown. This folding configuration is known, and the laminated sheets are folded by inserting one side of the front laminated sheet S1 and one side of the rear laminated sheet S3 into the valley fold of the laminated sheet S2. As a result, the laminated sheets are sequentially removed from the package (paper box, plastic bag, etc.) being stored by popping them out.

[0122] The reasons why the "arithmetic mean roughness Sa" of the surface measured by one-shot 3D (KEYENCE Co., Ltd.), the "compression work" and "compression recovery" measured by KES-G5 (KATO TECH Co., Ltd.) are suitable for "touch-up" are roughly as follows.

[0123] A small value for the "arithmetic mean roughness Sa" will result in a smooth surface.

[0124] When the value of "compression power" is large, the compression start phase is fast and long, thus giving it good softness.

[0125] A low "compression resilience" value means that once pressed in, it is difficult to return to its original shape, thus the pressure control becomes good, which helps to easily control the increase or decrease of force when wiping lipstick or foundation.

[0126]

Example

[0127] For samples of the paper towels produced in the embodiment and conventional paper towels, the following functional tests were conducted as evaluation items for each item in the functional test section. The physical properties, composition values, etc., of each sample were measured as follows. Regarding the physical properties, composition values, and test results of each sample, the results for the 3-ply case are shown in Tables 1 and 2, and the results for the 4-ply case are shown in Tables 3 and 4.

[0128] [Basis Weight]

[0129] Measurements were performed in accordance with JIS P 8124 (1998).

[0130] [Paper thickness]

[0131] As described above, under the conditions of JIS P 8111 (1998), the thickness was measured using a dial-type thickness gauge (thickness measuring instrument) "PEACOCK G type" (manufactured by Ozaki Manufacturing Co., Ltd.) according to the thickness measurement method described above.

[0132] [Dry Tensile Strength]

[0133] As already stated.

[0134] [Wet tensile strength]

[0135] The tensile test was performed according to JIS P 8135 (1998).

[0136] Regarding the test pieces, pieces approximately 25mm (±0.5mm) wide and 150mm long were used in both the longitudinal and transverse directions. Measurements were performed while maintaining the multi-layered nature of the paper towels. For the testing machine, a Minebea TG-200N tensile testing machine with a force sensor was used. The clamping interval was set to 100mm. The measurements were performed as follows: the test pieces, cured in a 105°C dryer for 10 minutes, were secured at both ends to the machine's clamps. Then, using a water-soaked pen, water was applied horizontally to the center of the test piece with a width of approximately 10mm. Immediately afterward, a tensile load was applied to the paper in the vertical direction, and the reading at the point of paper breakage (digital value) was recorded. The tensile speed was 50mm / min. Five sets of specimens were prepared in both the longitudinal and transverse directions, and five measurements were taken in each direction. The average of the measured values ​​was taken as the wet tensile strength in each direction.

[0137] [Softness]

[0138] Measurements were performed using a tactile measurement method based on JIS L 1096 E. The test piece was set to 100mm × 100mm in size, with a gap of 5mm. Measurements were taken five times each in the longitudinal and transverse directions using a single layer, and the average of all ten measurements was expressed as cN / 100mm. Softness is one of the indicators of suppleness. Measurements were taken using a single layer. When bonding using contact embossing or similar methods, the layers were carefully peeled off to avoid any contact embossing in the center of the test piece.

[0139] [MMD]

[0140] While the contact surface of the friction element is brought into contact with the surface of a test specimen subjected to a tension of 20 g / cm along a specified direction with a contact pressure of 25 g, the contact surface of the friction element is moved 2 cm at a speed of 0.1 cm / s in a direction approximately the same as the direction of the tension. The coefficient of friction at this time is measured using a friction tester KES-SE (manufactured by KATO TECH Co., Ltd.). The value obtained by dividing the coefficient of friction by the friction distance (movement distance = 2 cm) is MMD. The friction element has a contact surface formed by 20 adjacent piano wires P with a diameter of 0.5 mm, each 10 mm in length and width. A unit bulge is formed at the end of the contact surface by the 20 piano wires P (with a radius of curvature of 0.25 mm).

[0141] Furthermore, the measurement of MMD does not include the embossed and wrinkled parts beforehand.

[0142] On the other hand, the average value of the measurement samples is obtained by collecting one set of samples from each of the three parts of the bundle of laminated sheets, namely the upper part, the middle part, and the lower part, in any odd number of groups. The sheets are designated as the first layer (outer layer), the second layer (middle layer), and the third layer (outer layer) starting from the valley side of the three-layer (three-sheet) sheet.

[0143] Note 1 in the table (Determination of the coating surface): Two test pieces, each 2cm square, cut from each sheet, are gently floated in water on a spoon with the front and back sides facing up. After 30 seconds, the side with less water is designated as the coating surface (marked "CT"), and the other side is designated as the non-coating surface (marked "NCT"). If the coating surface is unclear, it is marked with "-".

[0144] Note 2 in the table shows values ​​obtained through one-shot 3D plane roughness measurements. [Functionality Test]

[0145] Using Comparative Example 2 as a benchmark, its rating was set to "4.0", which is the average of the ratings from 1 to 7 given by 12 evaluators. The higher the rating, the higher the evaluation.

[0146] The products in Comparative Examples 1 to 4 are commercially available products in China. The reference example is the applicant's prototype.

[0147] [Table 1]

[0148]

[0149] [Table 2]

[0150]

[0151] [Table 3]

[0152]

[0153] [Table 4]

[0154]

[0155] Based on the above results, it is possible to obtain 3- or 4-ply paper towels that reduce the stickiness of the outer surface while ensuring the necessary softness.

[0156] In the above experimental example, the determination of the surface to which the medicine was applied was simply carried out, but in more detail, it was found that the following method is preferred.

[0157] (1) Prepare a flat pan with 500mL of water, a spoon, and the sample.

[0158] (2) In the 3- or 4-layer laminated sheet, except for the embossed and pleated parts, cut out 2cm×2cm pieces and divide each piece into individual sheets (3 sheets or 4 sheets). Prepare 2 sets as test sheet A and test sheet B.

[0159] (3) Take the valley side of each separated sheet as side A (test sheet A) and its back side as side B (test sheet B). Mark side A with a red ballpoint pen.

[0160] (4) Place test piece A with side A facing up and test piece B with side B facing up on the spoon of the medicine spoon (about 20cm long).

[0161] (5) Make test piece A and test piece B float gently on the surface of water in the pan at the same time.

[0162] (6) After 30 seconds, observe the state of the water film and the light reflection on the test piece by visual inspection (photograph).

[0163] (7) The side of the test piece with significantly more water reflection is designated as the uncoated side (marked "NCT"). The opposite side is designated as the coated side (marked "CT").

[0164] (8) Judge by visual inspection (photographs). If there is no obvious difference, record both sides as "-".

[0165] exist Figure 8 and Figure 9 The test example is shown in the figure.

[0166] gaze related to test piece A Figure 8 In this case, the visible side is side A, which is the area where the medicine is applied. Although water wets the surface from the back, less of the upper surface (side A, the area where the medicine is applied) is exposed to water. This is believed to be because although water reaches the upper surface from below through the gaps (pores) in the paper, it is difficult for the medicine to spread on the upper surface due to its low surface tension.

[0167] In contrast, fixation was associated with test piece B. Figure 9 In this case, the surface seen is side B (the non-coated side), where water is moistened from the back. On the upper surface (side B, the non-coated side), more water is exposed. This is believed to be because, for water passing through the gaps (pores) in the paper from below, the surface tension is higher on the upper surface due to the less coating, making it easier for the water to diffuse.

[0168] In addition, regarding the "medicine content", each sheet conditioned to the standard conditions of JIS P8111 (23°C, 50%RH) contains 10.0 to 35.0% by mass.

[0169] When measuring the drug content, the drug solution coated on multiple layers of tissue paper is peeled off, and its weight is measured under the standard conditions of JIS P 8111 (a). Using a Soxhlet extractor, the test piece is placed in a solvent with an ethanol:acetone ratio of 50:50 and kept at a slight boiling state for approximately 3 hours to allow the drug solution coated on the tissue paper to dissolve. The test piece is then removed and dried at 60°C to a comparative weight, and its weight is measured (b). "Drug content (%)" is calculated as {(a) - (b)} ÷ (a) × 100. It refers to the mass ratio of the dried drug solution contained in the product.

[0170] Label Explanation

[0171] 6: Paper roll; 9: Gravure roll; 10: Blank roll; 10A, 10B: Stacked blank rolls; 11: Rotating staggered support; 1R~4R: Layer; F: Coated surface; W: Uncoated surface.

Claims

1. A paper towel which is a paper towel laminated with 3 or 4 layers, characterized in that, each layer contains a water-based moisturizer which exhibits hygroscopicity, with respect to the content of the water-based moisturizer among the layers, when the water-based moisturizer content ratio of the product is taken as 100, the water-based moisturizer content ratio of each layer is in the range of 92.0 to 108.0, each layer has a difference in the size of the arithmetic mean height Sa based on ISO 25178 between its two faces, the outer side face of each layer located on the outer side in the laminate of 3 or 4 layers is the face in which the arithmetic mean height Sa is small, and the content of the moisturizer of the outer side face of each layer located on the outer side in the laminate of 3 or 4 layers is more than that of the inner side face of the layer.

2. The paper towel according to claim 1, characterized in that, in the paper towel laminated with 3 or 4 layers, the content of the moisturizer of the face in which the arithmetic mean height Sa is small is more than that of the face in which the arithmetic mean height Sa is large, in the outer side face of each layer located on the inner side in the laminate of 3 or 4 layers.

3. The paper towel according to claim 1 or 2, wherein, the moisturizer is mainly composed of glycerin.

4. The paper towel according to claim 1 or 2, wherein, the content of the moisturizer in each layer is 10.0% to 35.0%.

5. The paper towel according to claim 1 or 2, wherein, The paper towel is a paper towel having 3 layers of paper, 1 layer of which has a basis weight of 15.0 g / m 2 ~ 22.5 g / m 2 , and 3 layers of which have a paper thickness of 140 μm ~ 270 μm.

6. The paper towel according to claim 1 or 2, wherein, The paper towel is a paper towel having 4 layers of paper, 1 layer of which has a basis weight of 15.0 g / m 2 ~ 22.5 g / m 2 , and 4 layers of which have a paper thickness of 180 μm ~ 360 μm.

7. The paper towel according to claim 1 or 2, wherein, the arithmetic mean height Sa based on ISO 25178 of the exposed face of the laminated sheet is 0.005 mm to 0.012 mm.

8. A paper towel product which is a paper towel product in which a paper towel laminated with 3 or 4 layers is housed in a housing body, characterized in that, each layer contains a water-based moisturizer which exhibits hygroscopicity, with respect to the content of the water-based moisturizer among the layers, when the average of the content in each layer is taken as 100, the content of the water-based moisturizer among the layers is in the range of 92.0 to 108.0, each layer has a difference in the size of the arithmetic mean height Sa based on ISO 25178 between its two faces, the outer side face of each layer located on the outer side in the laminate of 3 or 4 layers is the face in which the arithmetic mean height Sa is small, and the content of the moisturizer of the outer side face of each layer located on the outer side in the laminate of 3 or 4 layers is more than that of the inner side face of the layer.

9. The paper towel product according to claim 8, characterized in that, in the paper towel product in which a paper towel laminated with 3 or 4 layers is housed in a housing body, the content of the moisturizer of the face in which the arithmetic mean height Sa is small is more than that of the face in which the arithmetic mean height Sa is large, in the outer side face of each layer located on the inner side in the laminate of 3 or 4 layers.

10. The paper towel product according to claim 8 or 9, wherein, 3 layers 4 groups total 12 layers or 4 layers 3 groups total 12 layers 2 ~ 2.50 gf・cm / cm 2 and the compression recovery is 46.0% to 54.5%.

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