Hygiene tissue paper manufacturing method and hygiene tissue paper manufacturing device

Abstract

To provide a manufacturing method of multilayer-ply hygiene tissue paper for suppressing problems such as paper breakage during a manufacturing process.SOLUTION: A hygiene tissue paper manufacturing method includes the steps of: while unwinding a sheet for forming a middle layer from a first raw material roll, unwinding two or more plies of sheets for forming an outer layer from a second raw material roll; separating the two or more plies of sheets for forming the outer layer into individual plies; and sandwiching the sheet for forming the middle layer between the respective plies to form a multilayer ply, where one ply of the outer layer forming sheet unwound from the second raw material roll is fed while coming into contact with an upper surface of the first raw material roll, the one ply of the outer layer forming sheet and the middle layer forming sheet are laminated to form a continuous sheet, and the other ply of the outer layer forming sheet joins therewith to form a multilayer ply laminated in this order.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method and an apparatus for producing sanitary thin paper. [Background technology]

[0002] Sanitary tissue paper in roll or sheet form is produced by processing one or more layers of sanitary tissue paper into a predetermined size and shape. For example, a known example of sanitary tissue paper in roll form is roll toilet paper, which is made by winding a long piece of toilet paper into a roll.

[0003] Sanitary tissue paper in roll or sheet form, which is made by stacking three or more sheets, is also manufactured and sold to improve absorbency, etc. When manufacturing a three-ply toilet roll, for example, sheets can be unwound from three roll stands and stacked together.

[0004] Patent Document 1 discloses a method for manufacturing a four-ply toilet paper roll, which includes a first step of drawing out base paper from multiple base paper rolls, a second step of introducing the multiple base papers into a stacking section and stacking the multiple base papers to form four-ply toilet paper, a third step of drying the four-ply toilet paper, and a fourth step of winding up the four-ply toilet paper to manufacture a four-ply toilet paper roll. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 7276932 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, the development of multi-ply sanitary tissue paper, in which the middle and surface layers are made of different types of sheets, has been progressing with the aim of achieving both conflicting properties such as flexibility and strength. Even when the middle and surface layers are made of different types of sheets, a roll stand corresponding to the number of sheets to be stacked is usually used. Therefore, when manufacturing sanitary tissue paper with three or more plies, if sheets are unwound from three roll stands and stacked, the number of roll stands must be increased, necessitating major modifications to the manufacturing equipment. Furthermore, increasing the number of roll stands makes management of the manufacturing process more complicated.

[0007] One possible solution to this problem is to not increase the number of raw sheet stands (for example, to use two, which is the general number of raw sheet stands). However, if there is a difference in strength between the constituent sheets or if the constituent sheets are not strong enough (for example, when flexible sheets are used), problems such as paper breakage may occur during the manufacturing process.

[0008] Therefore, in order to solve these problems of the conventional technology, the inventors have conducted research with the aim of providing a method for manufacturing multi-ply sanitary tissue paper in which problems such as paper breakage are suppressed in the manufacturing process of multi-ply sanitary tissue paper, in which the middle layer and surface layer are made of different types of sheets. [Means for solving the problem]

[0009] Examples of specific embodiments of the present invention are given below.

[0010] [1] The method includes a step of unwinding a sheet for forming an intermediate layer from a first raw roll, unwinding two or more plies of sheets for forming an outer layer from a second raw roll, separating the two or more plies of sheets for forming an outer layer into individual plies, and sandwiching the sheet for forming an intermediate layer between the individual plies to form a multi-layer ply; A method for manufacturing sanitary thin paper, in which one ply of the outer layer forming sheet unwound from the second raw roll is fed while contacting the upper surface of the first raw roll, and a multi-layer ply is formed in which one ply of the outer layer forming sheet, the middle layer forming sheet, and the other ply of the outer layer forming sheet are stacked in this order. [2] A method for producing sanitary thin paper according to [1], wherein the second raw roll is arranged upstream of the first raw roll. [3] A method for producing sanitary thin paper described in [1], wherein the first raw roll is arranged upstream of the second raw roll. [4] The method for producing sanitary thin paper according to any one of [1] to [3], wherein the sheet for forming the middle layer is a one-ply or two-ply sheet. [5] The method for producing sanitary thin paper according to any one of [1] to [4], wherein the outer layer forming sheet contains at least one selected from a moisturizing agent and a softening agent. [6] A method for producing sanitary thin paper according to any one of [1] to [5], further comprising a step of embossing the multilayer ply. [7] A first raw roll formed by winding up a sheet for forming an intermediate layer and a second raw roll formed by winding up a sheet for forming two or more outer layers, a means for feeding one ply of the outer layer forming sheet unwound from the second raw roll while bringing it into contact with the upper surface of the first raw roll; A sanitary thin paper manufacturing device in which a multi-layer ply is formed by stacking one ply of an outer layer forming sheet, a middle layer forming sheet, and another ply of an outer layer forming sheet in this order. [Effects of the Invention]

[0011] According to the manufacturing method of the present invention, problems such as paper breakage can be suppressed when manufacturing multi-ply sanitary thin paper in which the middle layer and surface layer are made of different types of sheets. [Brief explanation of the drawings]

[0012] [Figure 1]FIG. 1 is a schematic diagram illustrating the configuration of toilet paper manufactured by the manufacturing device of this embodiment. [Figure 2] FIG. 2 is a diagram showing the configuration of the manufacturing apparatus of this embodiment. [Figure 3] FIG. 3 is a diagram showing the configuration of a manufacturing apparatus according to this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will be described in detail below. The following description may be based on representative embodiments and specific examples, but the present invention is not limited to such embodiments. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0014] (Manufacturing method of sanitary tissue paper) This embodiment relates to a method for producing sanitary thin paper, including the steps of: unwinding a middle layer forming sheet from a first roll; unwinding two or more outer layer forming sheets from a second roll; separating the two or more outer layer forming sheets into individual plies; and sandwiching the middle layer forming sheet between the individual plies to form a multi-layer ply. In this method for producing sanitary thin paper, one of the outer layer forming sheets unwound from the second roll is fed while contacting the upper surface of the first roll, forming a multi-layer ply in which one of the outer layer forming sheets, the middle layer forming sheet, and the other outer layer forming sheet are stacked in this order. Note that, in this specification, "multi-layer ply" refers to a product with three or more plies.

[0015] In this embodiment, one ply of the outer layer forming sheet unwound from the second raw roll is fed while contacting the upper surface of the first raw roll, eliminating the need to install a new frame or the like in the manufacturing equipment, simplifying equipment design. Therefore, this embodiment can efficiently manufacture multi-ply sanitary tissue paper in which the middle layer and surface layer are composed of different types of sheets. This embodiment also makes it possible to laminate a highly flexible sheet on the surface layer, enabling the manufacture of highly flexible multi-ply sanitary tissue paper.

[0016] In addition, in this embodiment, one ply of the outer layer forming sheet unwound from the second raw roll is fed while contacting the upper surface of the first raw roll, so even if the strength of the outer layer forming sheet unwound from the second raw roll is weak, it is possible to prevent the outer layer forming sheet from being damaged. Furthermore, in this embodiment, one ply of the outer layer forming sheet unwound from the second raw roll is fed while contacting the upper surface of the first raw roll, so it is also possible to increase the feeding speed of the second raw roll and the first raw roll.

[0017] Examples of sanitary thin paper obtainable by the manufacturing method of this embodiment include tissue paper, toilet paper, paper towels (such as kitchen paper), toilet paper, and watting (cotton paper). Among these, toilet paper is preferably used as the sanitary thin paper. FIG. 1 illustrates a toilet roll as an example of rolled sanitary thin paper. The toilet roll is a multi-ply product, and is a multi-ply product with three or more plies. The number of plies is more preferably three to ten, and even more preferably three or four. As shown in FIG. 1, for example, the rolled sanitary thin paper obtainable by the manufacturing method of this embodiment is a three-ply toilet roll. FIG. 1 illustrates a toilet roll 100, and the toilet paper 20 constituting the toilet roll 100 is a three-ply toilet paper, having an outer layer toilet paper 20a, an outer layer toilet paper 20b, and a middle layer toilet paper 20c sandwiched between them.

[0018] FIG. 2 is a diagram illustrating the manufacturing process of sanitary thin paper according to this embodiment. As shown in FIG. 2, in this manufacturing method of sanitary thin paper, a middle layer forming sheet c is unwound from a first raw roll 30, while two or more outer layer forming sheets a and b are unwound from a second raw roll 40. The two or more outer layer forming sheets a and b are separated into individual plies, and then a middle layer forming sheet c is sandwiched between the individual plies to form a multi-layer ply e (a multi-layer ply stacked in the order b / c / a). In this embodiment, as shown in FIG. 2, one of the outer layer forming sheets a unwound from the second raw roll is fed while contacting the upper surface of the first raw roll 30. Then, the other outer layer forming sheet b joins with a continuous sheet d, which is a laminate of one of the outer layer forming sheets a and the middle layer forming sheet c, to form the multi-layer ply e.

[0019] In this embodiment, the outer layer forming sheet is a sheet with two or more plies. The number of plies in the outer layer forming sheet is preferably 2 or more and 5 or less, more preferably 2 or 4 or less, even more preferably 2 or 3, and particularly preferably 2. When the outer layer forming sheet is separated into each ply in the manufacturing process of sanitary thin paper, each ply is separated into one or more sheets. For example, if the outer layer forming sheet is a two-ply sheet, the outer layer forming sheet is separated into one ply each in the process of separating into each ply. If the outer layer forming sheet is a three-ply sheet, the outer layer forming sheet is separated into one ply and two plies in the process of separating into each ply. If the outer layer forming sheet is a four-ply sheet, the outer layer forming sheet may be separated into two plies and two plies, or one ply and three plies in the process of separating into each ply.

[0020] In this embodiment, the intermediate layer forming sheet is a sheet of one or more plies. The number of plies of the intermediate layer forming sheet is more preferably 1 to 5, more preferably 1 to 3, and even more preferably 1 or 2.

[0021] The sheets constituting the outer layer forming sheet may be different types of sheets, but are preferably all the same type of sheets from the viewpoint of the manufacturing efficiency of the raw roll. Similarly, when the middle layer forming sheet is a sheet of two or more plies, the sheets constituting the middle layer forming sheet may be different types of sheets, but are preferably all the same type of sheets from the viewpoint of the manufacturing efficiency of the raw roll.

[0022] On the other hand, the outer layer forming sheet and the middle layer forming sheet are different types of sheets. For example, the outer layer forming sheet and the middle layer forming sheet may differ in the type and content of additives contained therein, or in the type and content of pulp constituting the sheet. Furthermore, the outer layer forming sheet and the middle layer forming sheet may be made using different papermaking methods or other processing steps. As a result, the outer layer forming sheet and the middle layer forming sheet may have different physical properties. For example, since the outer layer forming sheet comes into direct contact with the user's skin during use, it is preferable that the sheet be highly flexible. By using a sheet with excellent strength as the middle layer forming sheet, sanitary tissue paper with excellent flexibility and strength can also be produced. In such cases, the outer layer forming sheet may contain at least one selected from a humectant and a softener.

[0023] The TS7 value obtained by the TSA tissue softness measuring device (hereinafter simply referred to as the TSA measuring device) when measuring two outer layer forming sheets is preferably 15 or less. On the other hand, the TS7 value of the middle layer forming sheet is preferably 16 or more. The human feel (touch) of sanitary tissue paper is affected by characteristics such as "softness," "smoothness / roughness," and "rigidity." The TSA measuring device quantifies parameters that indicate these characteristics (referred to as TS7 (softness), TS750 (smoothness / roughness), and D (rigidity) respectively) through acoustic and deformation measurements. During measurement, TS7 generates strong vibrations due to the TSA blade, while relatively soft fibers may generate weaker vibrations due to the blade. This vibration is measured at the frequency of the acoustic spectrum and processed by the TSA software to obtain TS7. It is generally believed that the higher the TS7 value of sanitary tissue paper, the harder the sanitary tissue paper. In this embodiment, the smaller the TS7 value, the softer the feel on the skin.

[0024] The geometric mean of the dry tensile strength in the longitudinal direction (MD) and the width direction (CD) of the sheet for forming an intermediate layer is preferably 1 N or more. Furthermore, the geometric mean of the dry tensile strength in the longitudinal direction (MD) and the width direction (CD) of the sheet for forming an intermediate layer is preferably greater than the geometric mean of the dry tensile strength in the longitudinal direction (MD) and the width direction (CD) of the sheet for forming an outer layer. The dry tensile strength in the longitudinal direction (MD) and the width direction (CD) of each sheet is measured using a sample width of 15 mm, a span width of 100 mm, and a pulling speed of 50 mm / min. An AUTOGRAPH testing machine manufactured by Shimadzu Corporation can be used as the tensile tester, for example.

[0025] The geometric mean of the wet tensile strength in the longitudinal direction (MD) and the width direction (CD) of the sheet for forming the intermediate layer is preferably 0.55 N or more. Furthermore, the geometric mean of the wet tensile strength in the longitudinal direction (MD) and the width direction (CD) of the sheet for forming the intermediate layer is preferably greater than the geometric mean of the wet tensile strength in the longitudinal direction (MD) and the width direction (CD) of the sheet for forming the outer layer. To measure wet tensile strength, first, a test piece is placed in a tester with a six-ply sample width of 15 mm and a span width of 100 mm. Next, a sponge measuring 20 mm in length and 5 mm in width is placed on both ends of tweezers, and the sponge is immersed in ion-exchange water. The sample is then clamped at the center to prepare a sample for wet strength measurement. The maximum load in both the MD and CD directions is immediately measured at a tensile speed of 50 mm / min. For example, an AUTOGRAPH tester manufactured by Shimadzu Corporation can be used as the tensile tester.

[0026] In this embodiment, the intermediate layer forming sheet preferably has a crepe (numerous wrinkles) and a plurality of ridge (concave and convex) structures, and in this case, the crepe and the ridge (concave and convex) preferably intersect at right angles. In this specification, the spacing between convex portions in the ridge (concave and convex) structure is preferably 0.4 to 1.5 mm, more preferably 0.4 to 1.3 mm or 0.4 to 1.1 mm. For example, it is preferable that the intermediate layer forming sheet has a crepe formed in the width direction (CD) and a plurality of ridge (concave and convex) structures formed in the longitudinal direction (MD).

[0027] As shown in Fig. 2, the second web roll 40 is preferably disposed upstream of the first web roll 30. In this case, two or more plies of the outer layer forming sheet A are unwound from the second web roll 40 disposed upstream, and the outer layer forming sheet A separated into each ply is fed while contacting the upper surface of the first web roll 30 disposed downstream. By disposing the second web roll 40 upstream of the first web roll 30, the distance over which the outer layer forming sheet A is transported in one ply can be shortened, and breakage of the outer layer forming sheet A can be effectively suppressed.

[0028] 3, in this embodiment, the first raw web roll 30 may be disposed upstream of the second raw web roll 40. In this case, two or more plies of the outer layer forming sheet are fed from the second raw web roll 40 disposed downstream, and the outer layer forming sheet A separated into each ply is fed while contacting the upper surface of the first raw web roll 30 disposed upstream.

[0029] The sheet unwinding speed from the first raw roll is preferably 5 m / min or more, more preferably 10 m / min or more, and even more preferably 20 m / min or more. The sheet unwinding speed from the first raw roll is preferably 1000 m / min or less, more preferably 900 m / min or less, and even more preferably 800 m / min or less. The sheet unwinding speed from the second raw roll is preferably about the same.

[0030] As shown in Figures 2 and 3, the tension of the unwound sheet may be controlled by fine-tuning the unwinding speed of the sheet from the first raw sheet roll 30 and / or the sheet from the second raw sheet roll 40 using a tension detection device consisting of two rolls 51, 52, 61, 62 and dancer rolls 50, 60 placed between them that are displaced by the tension of the sheet.

[0031] The method for producing sanitary thin paper of this embodiment may include a step of applying a moisturizing liquid to either or both of the outer layer forming sheet and the middle layer forming sheet. For example, by applying a moisturizing liquid to the outer layer forming sheet before the step of forming the multilayer ply, the flexibility of the outer layer can be increased, and as a result, the usability of the sanitary thin paper can be improved. Furthermore, when applying a moisturizing liquid to the outer layer forming sheet, the moisturizing liquid may be applied before forming the second raw roll. Furthermore, the method for producing sanitary thin paper of this embodiment may include a step of applying an adhesive to the middle layer forming sheet before the step of forming the multilayer ply, and the outer layer forming sheet may be laminated after applying an adhesive to the middle layer forming sheet to improve the adhesion between the sheets.

[0032] The method for producing sanitary thin paper of this embodiment may further include a step of embossing a multi-layer ply formed by stacking one ply of outer layer-forming sheets, a middle layer-forming sheet, and another ply of outer layer-forming sheets in this order. The embossing is performed by pressing the sheet with an embossing roll. By changing the pressing amount or pressing pressure of the embossing roll, an embossed shape having a predetermined embossing height can be formed in the sanitary thin paper. In this embodiment, the embossing may be performed on each sheet before the multi-layer ply is formed, or may be performed while the multi-layer ply is being formed.

[0033] In this embodiment, when embossing is performed, embossing may be performed on only some of the multi-layer plies. For example, embossing may be performed on only one of the multiple outer layer forming sheets and / or only one of the multiple middle layer forming sheets. In this way, embossing only some of the plies can more effectively prevent paper breaks during the manufacturing process. Also, in this embodiment, embossing may be performed only on the middle layer forming sheets. In this case, the outer layer forming sheets, which have relatively low strength, are not embossed to prevent paper breaks, while the middle layer forming sheets, which have relatively high strength, are embossed to form voids between the layers, improving diffusion during water absorption and increasing the thickness of the sanitary thin paper as a whole, thereby improving the feel to the touch.

[0034] Furthermore, in the present embodiment, when embossing is performed and the outer layer forming sheet is multi-ply and the middle layer forming sheet is multi-ply, the embossing may be performed in a stacked state of one outer layer forming sheet and one middle layer forming sheet. This eliminates the need to emboss only one layer of the outer layer forming sheet, even when the outer layer forming sheet is a low-strength sheet, thereby reducing the risk of paper breakage and increasing production speed. Note that when embossing is performed in a stacked state as described above, a step of separating the embossed laminated sheets after the embossing process creates a misalignment in the positions of the respective convex portions. This creates gaps between the sheets, improving absorption and diffusion, and also increases the thickness, resulting in a softer feel.

[0035] A multi-layer ply formed by laminating one ply of an outer layer-forming sheet, a middle layer-forming sheet, and another ply of an outer layer-forming sheet in this order may have narrow contact embossments (joining embossments) in the areas that will become the widthwise ends, or the ends may be coated with an adhesive or the like to bond them together. When a contact embossment is provided, it is preferable that the contact embossment be formed, for example, on both side edges in the width direction (CD) of the sanitary paper, extending along its longitudinal direction (MD). The contact embossment may be formed so as not to protrude outward in the thickness direction from either the front or back of the sanitary paper.

[0036] The sanitary tissue paper of this embodiment is preferably a roll of sanitary tissue paper. In this case, the manufacturing method of sanitary tissue paper of this embodiment preferably includes a winding step in which a multi-layer ply formed by stacking one ply of an outer layer sheet, a middle layer sheet, and another ply of an outer layer sheet in this order is wound into a roll. In the winding step, the winding may be performed while forming tear perforations that run across the width of the paper at regular intervals along the length. In the end processing section of the winding, the end of the long sanitary paper discharged from the winding section is preferably glued along the width to prevent the long sanitary paper from unraveling. The resulting roll is cut to a predetermined width to produce a sanitary paper roll product.

[0037] <Manufacturing method of raw roll> The middle layer forming sheet constituting the first raw roll and the outer layer forming sheet constituting the second raw roll can each be obtained by making a pulp slurry using a known papermaking machine. In this embodiment, the pulp slurries forming the middle layer forming sheet and the outer layer forming sheet are preferably different. For example, the pulp slurry forming the middle layer forming sheet and the pulp slurry forming the outer layer forming sheet may each contain different types or amounts of additives, or may contain different types or amounts of pulp.

[0038] Pulp components contained in the pulp slurry include wood pulp, non-wood pulp, and deinked pulp. Examples of wood pulp include chemical pulps such as hardwood pulp (hardwood kraft pulp (LKP)), softwood pulp (softwood kraft pulp (NKP)), sulfite pulp (SP), dissolving pulp (DP), soda pulp (AP), unbleached kraft pulp (UKP), and oxygen-bleached kraft pulp (OKP). Other examples include semi-chemical pulps such as semi-chemical pulp (SCP) and chemi-ground wood pulp (CGP), and mechanical pulps such as groundwood pulp (GP) and thermomechanical pulp (TMP, BCTMP). Examples of non-wood pulp include cotton-based pulps such as cotton linters and cotton lint, non-wood pulps such as hemp, straw, and bagasse, and cellulose, chitin, and chitosan isolated from sea squirts and seaweed. The deinked pulp may be made from recycled paper. The pulp may be one of the above types used alone or a mixture of two or more types.

[0039] The pulp component is preferably at least one selected from softwood pulp and hardwood pulp. In particular, in the present invention, it is preferable to use a combination of softwood pulp and hardwood pulp, and it is more preferable to use a combination of softwood kraft pulp (NKP) and hardwood kraft pulp (LKP).

[0040] Before the step of making paper from the pulp slurry, a step of bleaching the fiber raw material may be included. As the bleaching agent used in the bleaching step, known bleaching agents such as oxygen-based bleaching agents and chlorine-based bleaching agents can be used.

[0041] The step of preparing the pulp slurry may include a step of beating the pulp components. In the beating step, for example, a double-disc refiner or the like may be used for beating treatment. During the beating treatment, for example, the softwood pulp and the hardwood pulp may be beaten separately, or they may be mixed and then beaten.

[0042] The pulp slurry may contain optional components in addition to the pulp component. Examples of optional components include dry strength agents, wet strength agents, softeners, and humectants. Examples of dry strength agents include cationized starch, polyacrylamide (PAM), and carboxymethyl cellulose (CMC). Examples of wet strength agents include polyamide epichlorohydrin, urea, melamine, and thermally crosslinkable polyacrylamide. Examples of softeners include anionic surfactants, nonionic surfactants, cationic surfactants, and zwitterionic surfactants. Examples of humectants include glycerin, diglycerin, propylene glycol, 1,3-butylene glycol, polyethylene glycol, sorbitol, glucose, xylitol, maltose, maltitol, mannitol, trehalose, polyglycerin, lactic acid, and sodium lactate. In particular, the pulp slurry for forming the outer layer sheet preferably contains at least one selected from humectants and softeners.

[0043] Examples of paper machines for making paper from pulp slurry include suction breast formers (cylinder type, Fourdrinier type), twin wire formers, cylinder formers (C-wrap, S-wrap), and crescent formers.

[0044] A papermaking machine that makes pulp slurry generally includes a wire part, a press part, a dryer part, a calendar part, and a reel part. The wire part is a process in which the supplied slurry is dehydrated to form a sheet. In the wire part, the pulp slurry is supplied to a forming unit to form sheets that will become outer layer forming sheets and middle layer forming sheets. The papermaking machine can also form sheets with two or more layers. In the forming unit, the component blending ratios of the pulp slurry that form each layer can be made different. This allows the properties of each layer that constitutes the outer layer forming sheet and the middle layer forming sheet to be different.

[0045] In the process of making paper from the pulp slurry, the ratio of the water flow rate to the wire speed (jet wire ratio (J / W ratio)) may be adjusted so that the basis weight per ply of the outer layer forming sheet and the middle layer forming sheet falls within a predetermined range and the strength of each sheet falls within a desired range. The jet wire ratio is the ratio of the slurry supply rate to the wire running speed. When the jet wire ratio is greater than 1, the slurry supply rate is faster than the wire running speed, and this is called "push formation." When the jet wire ratio is 1 or less, the slurry supply rate is slower than the wire running speed, and this is called "pull formation." The jet wire ratio (J / W ratio) is preferably adjusted to, for example, 0.90 or more and 1.05 or less.

[0046] In the process of making paper from the pulp slurry, for example, a method of making paper from a pulp slurry that is a mixture of softwood pulp and hardwood pulp to form a single uniform layer of wet paper, or a method of making a softwood pulp layer and a hardwood pulp layer together to form a single sheet of wet paper, and either method may be adopted.

[0047] In the press part of a papermaking machine, pressure is applied to the sheet to dehydrate it. In the press part, pressure is applied to the sheet formed in the wire part to squeeze out the water from the sheet. By applying pressure to the sheet in the press part, the surface of the sheet is made smooth and the density of the pulp component can also be adjusted.

[0048] In the dryer part, the sheet obtained through the press part is dried. The drying process is preferably, for example, a process of blowing hot air toward the wet paper or a process of pressing the wet paper against the outer surface of the Yankee dryer. In the drying process using the Yankee dryer, the dried paper can be scraped off from the Yankee dryer with a doctor blade (creping process) to form crepe-like wrinkles. The crepe rate is calculated by (Yankee dryer speed - reel speed) / reel speed x 100. By setting the crepe rate within the above range, the softness and strength of the sanitary thin paper can be effectively improved.

[0049] The manufacturing process of the outer layer forming sheet and the intermediate layer forming sheet may include a calendering step. The calendering step is carried out in a calender part. In the calender part, the surface of the dried sheet is stretched while being pressed to smooth the surface of the sheet.

[0050] In the reel part, the sheet obtained through the above steps is wound up to form roll bodies (first raw web roll and second raw web roll). At this time, it is preferable to wind up the sheet so that the surface of the sheet that is pressed against the Yankee dryer becomes the outer peripheral surface of the raw web roll.

[0051] (Hygienic tissue paper manufacturing equipment) This embodiment relates to a sanitary thin paper manufacturing device having a first raw roll formed by winding up a middle layer forming sheet and a second raw roll formed by winding up two or more plies of outer layer forming sheets, and equipped with a means for feeding one ply of the outer layer forming sheet unwound from the second raw roll while contacting the upper surface of the first raw roll. The sanitary thin paper manufacturing device of this embodiment forms a multi-layer ply by stacking one ply of the outer layer forming sheet, the middle layer forming sheet, and the other ply of the outer layer forming sheet in this order. The sanitary thin paper manufacturing device of this embodiment can form three or more multi-layer plies by providing two raw rolls, the first raw roll and the second raw roll, even when producing three or more plies of sanitary thin paper, so that large-scale modifications to the manufacturing equipment are unnecessary and process management is easy.

[0052] As shown in FIG. 2, the sanitary thin paper manufacturing apparatus of this embodiment includes a first raw roll 30 wound with a middle layer forming sheet c and a second raw roll 40 wound with two or more plies of outer layer forming sheets a and b. The sanitary thin paper manufacturing apparatus of this embodiment includes a means for feeding one ply a of the outer layer forming sheets a and b unwound from the second raw roll 40 while bringing it into contact with the upper surface of the first raw roll 30. Examples of such a means include a paper feeding means that uses tension generated by the unwound roll and the downstream winding and embossing processes. Furthermore, by driving a roll that guides the sheet transport and assisting the sheet transport, the sheet transport can be stabilized and the risk of paper breaks can be reduced. In this embodiment, as shown in Figure 2, one ply a of the outer layer forming sheet unwound from the second raw roll is fed while contacting the upper surface of the first raw roll 30, and then the other ply b of the outer layer forming sheet joins with a continuous sheet d in which one ply a of the outer layer forming sheet and a middle layer forming sheet c are laminated, thereby forming a multi-layer ply e.

[0053] The first web roll 30 and the second web roll 40 are each rotatably attached to a web roll stand, and are driven to rotate by a sheet feeding device (not shown) to feed out their respective sheets. In this embodiment, the tension of the fed sheet may be controlled by finely adjusting the sheet feeding speed using a device that detects the tension of the sheet, such as a dancer roll.

[0054] The sanitary thin paper manufacturing apparatus of this embodiment can use any known device that can unwind each raw roll at a predetermined unwinding speed and that can continuously change this unwinding speed. The sheet unwinding device may, for example, adjust the sheet unwinding speed by controlling the rotation speed of a drive unit that can rotate a shaft inserted through the core of each raw roll. Alternatively, the sheet unwinding device may adjust the sheet unwinding speed by controlling the rotation drive speed of a rotary drive belt that contacts the outer periphery of each raw roll and rotates each raw roll. Control of the rotation speed and rotation drive speed for adjusting the unwinding speed can be achieved, for example, by changing the voltage or current supplied to the drive unit.

[0055] As shown in Fig. 2, the second web roll 40 is preferably disposed upstream of the first web roll 30. In this case, two or more plies of outer layer forming sheet are unwound from the second web roll 40 disposed upstream, and the outer layer forming sheet a separated into each ply is fed while contacting the upper surface of the first web roll 30 disposed downstream. Dancer rolls 50 and 60 may be provided downstream of the second web roll 40 and the first web roll 30, respectively. In this case, when the outer layer forming sheet a separated into each ply unwound from the second web roll 40 is fed toward the first web roll 30, the outer layer forming sheet a may be fed via the dancer roll 50 or without the dancer roll 50. 2, when the outer layer forming sheet a separated into each ply and unwound from the second raw web roll 40 is fed toward the first raw web roll 30, the outer layer forming sheet a may be fed to the top of the first raw web roll 30 via the dancer roll 50, and then the outer layer forming sheet a may be fed without passing through the dancer roll 60 provided downstream of the first raw web roll 30. This allows the dancer rolls 50 and 60 to control the unwinding speed of each raw web roll, thereby improving unwinding stability.

[0056] In this embodiment, as shown in Fig. 3, the first web roll 30 may be disposed upstream of the second web roll 40. In this case, two or more plies of outer layer forming sheet are unwound from the second web roll 40 disposed downstream, and the outer layer forming sheet a separated into each ply is fed while contacting the upper surface of the first web roll 30 disposed upstream. In the embodiment of Fig. 3 as well, dancer rolls 50 and 60 may be provided downstream of the second web roll 40 and the first web roll 30, respectively.

[0057] Examples of the outer layer forming sheets and middle layer forming sheets used in the sanitary thin paper manufacturing apparatus of this embodiment include those described above, and the manufacturing methods of these sheets can also be appropriately adopted as described above.

[0058] The sanitary thin paper manufacturing apparatus of this embodiment may include a means for applying a moisturizing liquid to either or both of the outer layer forming sheet and the middle layer forming sheet. Examples of the means for applying the moisturizing liquid include a moisturizing liquid applicator (e.g., a coater, a sprayer, etc.). For example, applying a moisturizing liquid to the outer layer forming sheet can increase the flexibility of the surface layer, thereby improving the usability of the sanitary thin paper. The sanitary thin paper manufacturing apparatus of this embodiment may also have a means for applying an adhesive to the middle layer forming sheet, and the adhesive may be applied to the middle layer forming sheet before the outer layer forming sheet is laminated to increase the adhesion between the sheets.

[0059] The sanitary thin paper manufacturing apparatus of this embodiment may include an embossing unit. The embossing unit applies pressure to the sheet using an embossing roll. By changing the pressing amount or pressing pressure of the embossing roll, an embossed shape with a predetermined embossing height can be formed in the sanitary thin paper.

[0060] The embossing means comprises a roll set consisting of an embossing roll and a backup roll, the backup roll being displaceable by any known means, for example an air cylinder.

[0061] The backup roll may be configured so that it can be selectively displaced between a first position in contact with the embossing roll and a second position spaced apart from the embossing roll by displacement of the backup roll.

[0062] The embossing roll is a roll having a concave-convex portion on its outer surface corresponding to a desired embossing pattern. At least the concave-convex portion of the embossing roll is made of metal, and the embossing roll may be a male (convex) steel roll. This embossing roll is rotated by a driving means (not shown).

[0063] The backup roll is a driven roll that is used in contact with the embossing roll and has a cylindrical outer shape. The surface of the backup roll is made of a hard rubber-like elastic material such as elastically deformable hard synthetic rubber.

[0064] When embossing, the sheet transported from each raw roll to the embossing section is inserted into a paper path passing between a backup roll and an embossing roll. The sheet is pressed against the embossing roll by the backup roll, and receives the driving force of the embossing roll, and is sent to the downstream side of the roll set. This pressure between the backup roll and the embossing roll forms embosses in the sheet.

[0065] In addition, when embossing of the sheet is not required, such as when manufacturing a non-embossed toilet roll, the sheet transported from each raw roll may be guided downstream without coming into contact with the embossing roll, for example, by being guided only to the backup roll.

[0066] Furthermore, the sanitary thin paper manufacturing device of this embodiment may be equipped with an edge joining means. The edge joining means may provide narrow contact embossments (joining embossments) in the region that will become the widthwise edge of a multi-layer ply formed by stacking one ply of an outer layer forming sheet, a middle layer forming sheet, and another ply of an outer layer forming sheet in this order, or bonding may be performed by applying an adhesive or the like to the edge. When providing contact embossments, it is preferable that the contact embossed portions are formed, for example, on both side edges in the width direction (CD direction) of the sanitary paper so as to extend along its longitudinal direction (MD direction). The contact embossed portions may be formed so as not to protrude outward in the thickness direction from either the front or back side of the sanitary paper.

[0067] A perforation forming unit and a winding unit may be further arranged in this order downstream of the embossing unit.

[0068] The sanitary tissue paper of this embodiment is preferably a roll of sanitary tissue paper. In this case, the sanitary tissue paper manufacturing device of this embodiment preferably has a winding means for winding a multi-layer ply, which is formed by stacking one ply of an outer layer sheet, a middle layer sheet, and another ply of an outer layer sheet in this order, into a roll. The sanitary tissue paper manufacturing device of this embodiment may also include a cutter that forms tear perforations that run across the width at regular intervals along the length. For example, the tear perforations may be formed by the cutter while the sanitary tissue paper is being wound. In addition, in the end processing section of the winding, the end of the long sanitary paper discharged from the winding section is preferably glued along the width to prevent the long sanitary paper from unraveling. The resulting winding is cut to a predetermined width to produce a sanitary paper roll product. [Explanation of symbols]

[0069] 20. Toilet paper 20a outer layer toilet paper 20b outer layer toilet paper 20c medium-ply toilet paper 30 First roll of raw fabric 40 Second roll of raw material 50 Dancer Roll Rolls 51 and 52 60 Dancer Roll Rolls 61 and 62 100 toilet rolls a) Outer layer forming sheet b. Outer layer forming sheet c. Middle layer forming sheet d. A sheet in which one ply a of the outer layer forming sheet and the middle layer forming sheet b are laminated. e Multi-layer ply

Claims

1. The method includes a step of unwinding a sheet for forming an intermediate layer from a first raw roll while unwinding two or more plies of sheets for forming an outer layer from a second raw roll, separating the two or more plies of sheets for forming an outer layer into individual plies, and sandwiching the sheet for forming an intermediate layer between the individual plies to form a multi-layer ply, A method for manufacturing sanitary thin paper, in which one ply of the outer layer forming sheet unwound from the second raw roll is fed while contacting the upper surface of the first raw roll, and a multi-layer ply is formed in which one ply of the outer layer forming sheet, the middle layer forming sheet, and the other ply of the outer layer forming sheet are stacked in this order.

2. The method for producing sanitary thin paper according to claim 1 , wherein the second raw roll is disposed upstream of the first raw roll.

3. The method for producing sanitary thin paper according to claim 1 , wherein the first raw web roll is disposed upstream of the second raw web roll.

4. The method for producing sanitary thin paper according to any one of claims 1 to 3, wherein the middle layer forming sheet is a one-ply or two-ply sheet.

5. The method for producing sanitary thin paper according to any one of claims 1 to 3, wherein the outer layer forming sheet contains at least one selected from a humectant and a softener.

6. The method for producing sanitary thin paper according to any one of claims 1 to 3, further comprising a step of embossing the multilayer ply.

7. The sheet has a first raw roll formed by winding up a sheet for forming an intermediate layer, and a second raw roll formed by winding up a sheet for forming two or more outer layers, a means for feeding one ply of the outer layer forming sheet unwound from the second raw roll while bringing it into contact with an upper surface of the first raw roll, A sanitary thin paper manufacturing apparatus in which a multi-layer ply is formed by stacking one ply of the outer layer forming sheet, the middle layer forming sheet, and the other ply of the outer layer forming sheet in this order.

Images