JP2016060988A - Papermaking method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a papermaking method for a tissue paper with sufficient paper durability as well as flexibility and smoothness to form excellent crepe by suppressing the paper from being peeled from the surface of a Yankee dryer roll.SOLUTION: A papermaking method includes: a first step of supplying a first papermaking raw material to which a flexibilizer, a dry paper strengthening agent and a wet paper strengthening agent are added to wires 12 and 13 of a wire part P; a second step of supplying a second papermaking raw material to which the flexibilizer, the dry paper strengthening agent and the wet paper strengthening agent are not added to the wires of the wire part; a third step in which a first paper layer mainly composed of the first papermaking raw material formed in the first step and a second paper layer mainly composed of the second papermaking raw material formed in the second step are laminated on each other; and a step of feeding a wet paper in such a manner that the second paper layer side of the wet paper Cformed in the third step can be in contact with the surface of a Yankee dryer roll 15 of a dry part P.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a papermaking method in which two layers of a first paper layer mainly composed of a first papermaking raw material and a second paper layer mainly composed of a second papermaking raw material are combined.

  As a raw material for thin paper such as tissue paper, both softwood pulp and hardwood pulp are mainly used. Normally, softwood pulp is rigid and can obtain a high tensile strength, but has a property of being inferior in flexibility and touch. On the other hand, hardwood pulp is thin and supple and has good flexibility and touch, but has a short fiber length and insufficient tensile strength. Therefore, in order to compensate for the mutual disadvantages of softwood pulp and hardwood pulp, papermaking raw materials mainly containing coniferous pulp and papermaking raw materials mainly containing hardwood pulp are taken into consideration in consideration of these characteristics. It is generally done. Such papermaking techniques are known from Patent Document 1 and Patent Document 2.

  In addition to this, a Yankee dryer is used in the dry part so that thin paper with a good hand feeling can be obtained. In this case, the surface of the paper layer mainly composed of hardwood pulp is smoothed by transferring the paper layer side mainly composed of hardwood pulp of the wet paper guided from the press part to the mirror roll of the Yankee dryer. Can be. By preparing two long base papers wound up in a roll shape in this way, pulling out the two base papers in a roll shape and stacking them so that the paper layer sides mainly composed of softwood pulp are in contact with each other In addition, a paper layer mainly composed of hardwood pulp is positioned on the surface side so that a good hand feeling can be obtained.

  Further, since this type of thin paper is required to have sufficient dry strength and wet strength, a papermaking raw material to which a dry paper strength agent and a wet strength agent are added is used. Similarly, a papermaking raw material to which a softener is further added as necessary to improve the softness of thin paper, particularly tissue paper, is also used, and these techniques are known in Patent Document 2 and Patent Document 3 and the like. Yes.

Japanese Patent No. 3216557 Japanese Patent No. 4762846 Japanese Patent No. 3010904

  When making thin paper such as tissue paper, the papermaking raw material supplied to the papermaking process contains a softening agent. This softening agent adheres to the Yankee dryer roll on the surface of the paper wrapped around it. It contains a component that lowers. For this reason, the paper is easily peeled off from the surface of the Yankee dryer roll, and it becomes difficult to form a good crepe when the paper is creped using a creping doctor.

  On the other hand, the dry paper strength agent and wet paper strength enhancer have the effect of increasing the strength of paper obtained by papermaking, but have properties that impair the flexibility and smoothness of paper obtained by papermaking. In particular, thin paper such as tissue paper contributes to a decrease in texture.

  An object of the present invention is to provide a papermaking method for thin paper, particularly tissue paper, which has a strength comparable to that of the conventional one and has a better texture.

  The papermaking method according to the present invention includes a first step of supplying a first papermaking raw material to which a softener, a dry paper strength agent, and a wet strength agent are added to a wire of a wire part, and a softener and a dry paper strength agent. And a second step of supplying a second papermaking raw material to which the wet paper strength enhancer is not added to the wire of the wire part, and a first step mainly comprising the first papermaking raw material formed in the first step. Formed in this third step, and a third step in which the second paper layer mainly composed of the second papermaking raw material formed in the second step is combined with each other. And feeding the wet paper so that the second paper layer side of the wet paper is in contact with the surface of the Yankee dryer roll of the dry part.

  In the present invention, the surface of the second paper layer mainly composed of the second papermaking raw material to which the softening agent, the dry paper strength agent, and the wet strength agent are not added is brought into contact with the Yankee dryer roll and smoothed. Define one side of the paper.

The papermaking method according to the present invention may further include a step of performing a creping process on the paper dried by the dry part. In this case, the paper to be made is preferably a thin paper having a basis weight in the range of 10 to ²⁰ g / m ² .

  The first papermaking raw material contains 20 to 100% by mass of softwood pulp with respect to the total mass of the pulp contained in the first papermaking raw material, and the second papermaking raw material is a pulp contained in the second papermaking raw material. It is effective to contain 90 to 100% by mass of hardwood pulp with respect to the total mass.

  When the ratio of the softening agent is less than 0.01% by mass with respect to the total mass of the pulp contained in the first and second papermaking raw materials, the effect of softness due to the use of the softening agent cannot be given to the paper. . On the contrary, when the ratio of the softening agent exceeds 0.5% by mass with respect to the total mass of the pulp contained in the first and second papermaking raw materials, the paper strength of the resulting paper is reduced, Accidents such as paper breaks occur during the manufacture of paper products. Therefore, it is effective to add the softening agent in the range of 0.01 to 0.5% by mass with respect to the total mass of the pulp contained in the first and second papermaking raw materials.

  Further, when the ratio of the dry paper strength agent is less than 0.02% by mass with respect to the total mass of the pulp contained in the first and second papermaking raw materials, the effect of improving the paper strength by using the dry paper strength agent. Cannot be given to paper. On the contrary, when the ratio of the dry paper strength agent exceeds 0.5% by mass with respect to the total mass of the pulp contained in the first and second papermaking raw materials, the flexibility and smoothness of the obtained paper are greatly impaired. It will be. Therefore, it is effective to add the dry paper strength agent in the range of 0.02 to 0.5% by mass with respect to the total mass of pulp contained in the first and second papermaking raw materials.

  Similarly, when the ratio of the wet paper strength enhancer is less than 0.02% by mass with respect to the total mass of the pulp contained in the first and second papermaking raw materials, the paper strength due to the use of the wet paper strength enhancer. The improvement effect cannot be given to paper. On the contrary, when the ratio of the wet paper strength enhancer exceeds 0.25% by mass with respect to the total mass of pulp contained in the first and second papermaking raw materials, the flexibility and smoothness of the obtained paper are large. It will be damaged. Therefore, it is effective to add the wet paper strength enhancer in the range of 0.02 to 0.25% by mass with respect to the total mass of pulp contained in the first and second papermaking raw materials.

  A softener, a dry paper strength agent and a wet paper strength enhancer must be added to the first papermaking raw material, and a softener, a dry paper strength agent and a wet paper strength enhancer must be added to the second papermaking raw material. What is necessary is just to add other chemical | medical agents, such as a yield improving agent and a coagulant | flocculant, to one or both of a 1st papermaking raw material and a 2nd papermaking raw material.

  According to the papermaking method of the present invention, the surface of the second paper layer to which the dry paper strength agent and the wet strength agent are not added is in contact with the surface of the Yankee dryer roll. It can be improved over things.

When the paper dried in the dry part is creped, the second paper layer does not contain a softening agent, so the adhesion to the Yankee dryer roll can be improved compared to the conventional one, and a good crepe can be obtained. It becomes possible to form. In particular, it is effective when making a thin paper such as tissue paper having a basis weight in the range of 10 to ²⁰ g / m ² .

  When the first papermaking raw material contains 20 to 100% by mass of softwood pulp with respect to the total mass of the pulp contained in the first papermaking raw material, the strength of the paper can be maintained by the first paper layer. Further, when the second papermaking raw material contains 90 to 100% by mass of hardwood pulp with respect to the total mass of the pulp contained in the second papermaking raw material, the second paper layer further increases the flexibility and smoothness of the paper. Can be improved.

  A softener is added in an amount of 0.01 to 0.5% by mass, and a dry paper strength agent is added in an amount of 0.02 to 0.5% by mass with respect to the total mass of pulp contained in the first and second papermaking raw materials. When the wet paper strength enhancer is added in an amount of 0.02 to 0.25% by mass, a paper having the required strength and desirable flexibility and smoothness can be produced.

It is a conceptual diagram which represents typically one Embodiment of the papermaking equipment of the sanitary paper by this invention. It is the conceptual diagram which extracted and expanded a part of wire part in embodiment shown in FIG.

  An embodiment in which the sanitary paper according to the present invention is applied to a set of two tissue papers will be described in detail with reference to FIGS. 1 and 2. However, the present invention is not limited to such an embodiment, and the tissue paper is not limited thereto. It can also be applied to other thin paper.

FIG. 1 schematically shows a paper making facility for manufacturing a base paper of a pair of tissue paper, and FIG. 2 schematically shows the wire part extracted and enlarged. That is, the papermaking equipment is equipped with a wire part P _W, a press part P _P, and a dry part P _D, and calendar Part P _C, and a reel part P _R.

In the wire part P _W, the paper stock in advance component is prepared contains water in large quantities and supplied to the forming unit 11 to be described later, to form a paper layer C ₁ of 2-ply combination as the prototype of the tissue paper. A large amount of water contained in the papermaking raw material is dehydrated here, and the wet paper C ₂ is formed by wires 12 and 13 (to be described later) of the forming unit 11, where the wet paper C ₂ is prepared.

In the press part P _P , pressure is applied to the wet paper C ₂ having a two-layered structure formed in the wire part P _W , and water contained in the wet paper C ₂ is squeezed out. Here, the surface of the wet paper web C ₂ is smoothed, and at the same time, the density of the pulp component constituting the main part of the wet paper web C ₂ is increased, thereby forming the strong wet paper web C ₂ .

In the dry part P _D , excess water of the wet paper C ₂ that has been wet through the press part P _P is heated by the Yankee dryer 14 to forcibly evaporate, thereby drying the wet paper C ₂ . . Paper C ₃ drying wound on the mirror roll 15 of a Yankee dryer 14, while being creped processed by creping doctor 16 is peeled off from the surface of the mirror roll 15, is transported to the calender part P _C.

In the calendar part P _C , the paper C _{3 in} a nearly completed state is passed between the pair of calendar rolls 17 so that the surface of the paper C ₃ is smoothed to increase its density and strength.

In the reel part P _R, resulting paper C _3, i.e. winding the base paper C as a single tissue paper into a roll. The material roll C _R of tissue paper obtained through this step was prepared two, by cutting by superimposing these on another process, typically a set of two sheets of tissue paper, as seen is obtained .

  The details of such a papermaking facility are well known in Japanese Patent Application Laid-Open No. 2010-275646.

The forming unit 11 in the present embodiment includes a forming roll 18, endless inner wires 12 and outer wires 13, a head box 19, a drive roll 20, a plurality of guide rolls 21, and tension rolls 22. . The driving force applied to the driving roll 20 is transmitted to the forming roll 18, the guide roll 21, and the tension roll 22 through a power transmission mechanism (not shown). These wires rotate at the same speed as they rotate synchronously. The wires 12 and 13 are respectively wound around a part of the outer periphery of the forming roll 18. As a result, a curved initial forming region Z is formed between the inner wire 12 and the outer wire 13 for papermaking of the paper layer C ₁ described later and its initial dewatering.

  The head box 19 in the present embodiment for simultaneously supplying two types of papermaking raw materials toward the curved initial forming region Z has two raw material chambers 23a and 23b therein. The first papermaking raw material obtained by the preparation equipment (not shown) is supplied to the first raw material chamber 23a, and the second papermaking raw material obtained by the preparation equipment (not shown) is supplied to the second raw material chamber 23b. Is supplied. What is important here is that most of the pulp contained in the second papermaking raw material is occupied by hardwood pulp. Further, a softening agent, a dry paper strength agent, and a wet paper strength enhancer are added to the first papermaking raw material supplied to the first raw material chamber 23a, whereas the first paper supply raw material supplied to the second raw material chamber 23b. These are not added to the papermaking raw material.

  The first papermaking raw material contains 20 to 100% by mass of softwood pulp with respect to the total mass of pulp contained in the first papermaking raw material, and a softener, a dry paper strength agent, and a wet paper strength enhancer are added. Yes.

  The softening agent is an agent for improving the softness of paper, and is added in an amount of 0.01 to 0.5% by mass with respect to the total mass of pulp contained in the first and second papermaking raw materials. As the softening agent, known ones such as anionic surfactants, nonionic surfactants, cationic surfactants, and zwitterionic surfactants can be used alone or in admixture of two or more.

  Further, the dry paper strength agent is a chemical for increasing the strength of paper in a dry state, and is 0.02 to 0.5% by mass with respect to the total mass of pulp contained in the first and second papermaking raw materials. Added. As the dry paper strength agent, known ones such as cationized starch, polyacrylamide, and carboxymethylcellulose (CMC) can be used alone or in admixture of two or more.

  On the other hand, the wet paper strength enhancer is a drug for suppressing a decrease in paper strength when the paper gets wet with water. By fixing the wet paper strength enhancer to pulp fibers that are easily loosened against water, the bond between the pulp fibers is maintained even when wet, making it difficult to loosen and break, and to increase some strength. Such an effect is obtained. As the wet paper strength enhancer, known ones such as polyamide / epichlorohydrin resin, urea resin, melamine resin, thermal crosslinkable polyacrylamide (PAM) can be used singly or in combination. This is added in an amount of 0.02 to 0.25% by mass based on the total mass of pulp contained in the first and second papermaking raw materials.

  On the other hand, the second papermaking raw material contains 90 to 100% by mass of hardwood pulp with respect to the total mass of the pulp contained in the second papermaking raw material. However, the softening agent, the dry paper strength agent and the wet paper strength enhancer are included. Does not include.

Thus, when two types of papermaking raw materials are jetted from the head box 19, the second paper layer B mainly composed of the second papermaking raw material is formed on the inner wire 12 side, and the second paper layer B is formed on the outer wire 13 side. A first paper layer A mainly composed of one papermaking raw material is formed. And these is to be conveyed to the press part P _P through the inner wire 12 a paper layer C ₁ states combined paper making two layers together from the initial forming region Z. In the present embodiment, the second paper layer B and the first paper layer A that define the paper layer C ₁ are mixed at the boundary portion, and it is possible to bring about a stronger bond between them. Therefore, at the boundary between the second paper layer B and the first paper layer A, the softening agent, the dry paper strength agent, and the wet paper strength enhancer contained in the first paper layer A are added to the second paper layer B. May penetrate to the side. However, the side that contacts each of the wires 12 and 13 is hardly affected by the mixing, and the ratios of the softwood pulp and the hardwood pulp contained in the first and second paper layers A and B, respectively, are approximately the first and second. It will appear with the ratio of the softwood pulp and the hardwood pulp contained in the second papermaking raw material. In particular, the surface of the second paper layer B is in a state where there are almost no softener, dry paper strength agent and wet strength agent.

The partition wall 24 that partitions the two stock chambers 23a and 23b extends toward the initial forming region Z. The longer the partition wall 24 is, the longer the first papermaking raw material is as a main component. Mixing between the paper layer A and the second paper layer B mainly composed of the second papermaking raw material can be reduced. For example, by projecting the partition wall 24 outward from the head box 19, the first paper layer A mainly composed of the first papermaking material and the second paper layer B mainly composed of the second papermaking material. It is possible to eliminate the mixing. The details of the wire part P _{W having} such a structure are well known in Japanese Patent Publication No. 62-38480.

In the forming unit 11 described above, the end portion of the inner wire 12 is the press part _PP.
Connect to wet paper C ₂ formed by a two-ply combined state is conveyed through the inner wire 12 on toward the press section P _P. Wet paper C ₂ in the wet state through the press part P _P is wound such that the second sheet layer B side is in contact with the surface of the mirror roll 15 of a Yankee dryer 14. For this reason, it is possible to make the surface side of the second paper layer B smoother, and to further improve the touch, coupled with the fact that the second paper layer B is mainly composed of hardwood pulp having a good touch. Is possible.

In the above-described embodiment, two types of papermaking raw materials are simultaneously supplied to the wire part P _W from one head box, but two types of papermaking raw materials are separately supplied to the wire part P _W from two head boxes. It is also possible. A more specific configuration of a papermaking facility using two head boxes is well known in Japanese Patent Application Laid-Open No. 2010-275646.

  Next, in order to confirm the effect of the present invention, Table 1 below shows the results of making thin paper using the paper making equipment shown in FIGS.

  In Table 1, the proportion of pulp in the papermaking raw material is the proportion of the total amount of pulp contained in the first and second papermaking raw materials. Thus, for example, the first papermaking raw material in Example 3 contains about 22% by mass of softwood pulp (N pulp), and the second papermaking raw material in Example 5 contains about 90% by mass of hardwood pulp (L pulp). means.

  The ratio of the additive in the papermaking raw material is the ratio of the softening agent, the dry paper strength agent, and the wet paper strength enhancer to the total amount of pulp contained in the first and second papermaking raw materials. As the softening agent, FS8010 manufactured by Seiko PMC Co., Ltd. was used. As the dry paper strength agent, Araffix 255 manufactured by Arakawa Chemical Industries, Ltd. was used. As the wet paper strength enhancer, DD4282 manufactured by Seiko PMC Co., Ltd. was used.

  The basis weight is in accordance with JIS P8124.

The dry tensile strength is based on JIS P8113. When targeting thin paper with a basis weight of about 10 to ²⁰ g / m ² , it is necessary to be 0.8 N / 15 mm or more in the vertical direction and 0.4 N / 15 mm or more in the horizontal direction. Accidents such as paper breakage occur during papermaking or paper product manufacturing.

The wet tensile strength conforms to JIS P8135. When thin paper having a basis weight of about 10 to ²⁰ g / m ² is targeted, it is 0.4 N / 25 mm or more in the vertical direction and 0.2 N / 25 mm or more in the horizontal direction. If the value is below this value, an accident such as a paper break will occur during papermaking or paper product manufacture.

  The sensory evaluation is divided into 5 levels (5: good, 4: slightly good, 3: normal, 2: slightly bad, 1: bad) regarding the flexibility and smoothness, and the average value of 20 testers for each gender The average value of 3.5 or less was ineligible.

  The stocks of Examples 1 to 6 all show the results that both the required tensile strength and the flexibility and smoothness are good.

  On the other hand, in Comparative Example 1, since the first papermaking raw material contains only about 18% by mass of N pulp, the wet tensile strength is insufficient. In Comparative Example 2, the second papermaking raw material is L pulp. Therefore, there is a problem in smoothness. Comparative Example 3 corresponds to the prior art, and since the softening agent, the dry paper strength agent and the wet paper strength enhancer are added to the second papermaking raw material, the flexibility and smoothness are examples. It can be recognized that it is inferior to 1-6. In Comparative Examples 4 and 5, which show a case where the amount of the softening agent added is too small and a case where it is too large, a decrease in flexibility and smoothness and a decrease in tensile strength occur. In Comparative Examples 6 and 7, which show cases where the amount of the dry paper strength agent added is too small and too large, a decrease in dry tensile strength and a decrease in flexibility and smoothness occur. Similarly, Comparative Examples 8 and 9 showing the case where the addition amount of the wet paper strength enhancer is too small and the case where the addition amount is too large cause a decrease in wet tensile strength and a decrease in flexibility and smoothness.

  It should be noted that the present invention should be construed only from the matters described in the claims, and in the above-described embodiment, all the changes and modifications included in the concept of the present invention are other than those described. Is possible. That is, all matters in the above-described embodiment are not intended to limit the present invention, and include any configuration not directly related to the present invention. To get.

P _W wire part P _P press part P _D dry part P _C calender part P _R reel part 11 Forming unit 12 Inner wire 13 Outer wire 14 Yankee dryer 15 Mirror surface roll 16 Creping doctor 17 Calendar roll 18 Forming roll 19 Head box 20 Drive Roll 21 Guide roll 22 Tension roll 23a, 23b Paper chamber 24 Partition wall A 2nd paper layer B 1st paper layer C ₁ paper layer C ₂ wet paper C ₃ paper C base paper C _R base paper roll Z Initial forming area

Claims (7)

A first step of feeding a first papermaking material to which the softener and the dry paper strength agent and the wet strength agent are added to the wire of the wire part;
A second step of feeding a second papermaking raw material to which the softener and dry paper strength agent and wet strength agent are not added to the wire of the wire part;
The first paper layer mainly composed of the first papermaking raw material formed in the first step and the second paper mainly composed of the second papermaking raw material formed in the second step. A third step of combining the layers together,
Feeding the wet paper so that the second paper layer side of the wet paper formed in the third step is in contact with the Yankee dryer roll surface of the dry part. .   The papermaking method according to claim 1, further comprising a step of performing a creping process on the paper dried by the dry part. The papermaking method according to claim 2, wherein the paper to be made is a thin paper having a basis weight in the range of 10 to ²⁰ g / m2.   The first papermaking raw material contains 20 to 100% by mass of softwood pulp with respect to the total mass of pulp contained in the first papermaking raw material, and the second papermaking raw material is contained in the second papermaking raw material. The papermaking method according to any one of claims 1 to 3, comprising 90 to 100% by mass of hardwood pulp with respect to the total mass of the pulp to be produced.   The softening agent is added in an amount of 0.01 to 0.5% by mass based on the total mass of pulp contained in the first and second papermaking raw materials. The paper making method according to crab.   6. The dry paper strength agent is added in an amount of 0.02 to 0.5% by mass based on the total mass of pulp contained in the first and second papermaking raw materials. The paper making method according to any one of the above.   The wet paper strength enhancer is added in an amount of 0.02 to 0.25% by mass based on the total mass of pulp contained in the first and second papermaking raw materials. The papermaking method according to any one of 6 above.