JP2016060989A - Papermaking method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tissue paper with sufficient paper durability as well as flexibility and smoothness.SOLUTION: A papermaking method includes: a first step of supplying a first papermaking raw material to which a dry paper strengthening agent and a wet paper strengthening agent are added but a flexibilizer is not 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 is added but 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 the dry part, a Yankee dryer is used. 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 A thin paper is formed by positioning a paper layer mainly composed of hardwood pulp on the surface side.

  Here, since this kind of thin paper is required to have sufficient dry strength and wet strength, a dry paper strength agent and a wet strength agent are added to the papermaking raw material. Moreover, in order to improve the softness | flexibility of a thin paper, especially tissue paper, adding a softening agent is also performed. These techniques are known from Patent Document 2 and Patent Document 3.

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

  A dry paper strength agent and a 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 the paper. On the other hand, as described above, the softening agent has the effect of improving the flexibility and feel of paper obtained by papermaking, but has the property of reducing the strength of paper.

  Since tissue paper is pulled out of a box or bag, it requires a certain degree of tensile strength, while it directly touches the skin, and therefore requires a smooth and soft texture. In order to improve the smooth and soft texture, adding softener to the papermaking raw material will reduce the strength of the paper, so more dry and wet paper strength agents will be added than when no softener is added. Therefore, it is necessary to ensure strength. However, since there is a limit to the amount of added drug that can be fixed on paper, the effect of each drug may be insufficient as a result.

  An object of the present invention is to provide a papermaking method for thin paper, particularly tissue paper, which has high strength and excellent texture.

  The papermaking method according to the present invention includes a first step of supplying a first papermaking raw material to which a dry paper strength agent and a wet strength agent are added and no softening agent is added to the wire of the wire part, and a softening agent is added. A second step of supplying a second papermaking material to which the dry paper strength agent and the wet strength agent are not added to the wire of the wire part; and the first papermaking material formed in the first step. A third step in which the first paper layer mainly composed of the second paper layer mainly composed of the second paper making raw material formed in the second step is combined with the third step; Feeding the wet paper so that the second paper layer side of the wet paper formed in the step is in contact with the Yankee dryer roll surface 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 is added and the dry paper strength additive and the wet paper strength enhancing agent are not added is in contact with the Yankee dryer roll and smoothed. Define one side of the stock to be made.

  If the amount of the softwood pulp is less than 20% by mass, the strength of the first papermaking raw material is insufficient with respect to the total mass of the pulp contained in the first papermaking raw material. In addition, the texture of the second papermaking material is inferior when the amount of hardwood pulp is less than 90% by mass with respect to the total mass of the pulp contained in the second papermaking material. Therefore, 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 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 of the pulp.

  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 dry paper strength agent and a wet paper strength enhancer are added to the first papermaking raw material, and no softening agent is added. A softening agent is added to the second papermaking raw material, and the dry paper strength agent and the wet paper strength are added. The force enhancer may not be added, and another agent such as a yield improver or a coagulant may be added to one or both of the first papermaking raw material and the second papermaking raw material.

  According to the papermaking method of the present invention, a dry paper strength agent and a wet paper strength enhancer are added to the first paper layer, and a softener is not added, and a softener is added to the second paper layer. In this case, the dry paper strength agent and the wet strength strength agent for obtaining the desired strength are obtained as compared with the case where each agent is added to both layers. The amount of the agent can be reduced. Since the amount of dry paper strength agent and wet strength agent is small, there is little flexibility and smoothness lost by the addition of these chemicals, and the flexibility and smoothness of paper are improved while ensuring the desired strength. Can do. Furthermore, the softness and smoothness can be further improved by adding a softening agent to the second paper layer for which a smooth and soft texture is desired.

  In other words, each drug is not added to all layers, but a different additive drug configuration is used, so that each drug is sufficiently fixed in each layer and each effect is sufficiently exhibited. Then, by superimposing these paper layers, flexibility and smoothness can be improved while ensuring strength. That is, it is possible to obtain a paper that sufficiently brings out the effects of each drug while suppressing the amount of the added drug.

  In addition, since the surface of the second paper layer to which the softener is added and the dry paper strength agent and the wet strength agent are not added is in contact with the surface of the Yankee dryer roll, the flexibility and smoothness are further improved. Can be made.

  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 0.02 to 0.25% by mass of the wet paper strength enhancer is added, paper having the strength required for the paper and the desired 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. In addition, 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, and a softening agent is not added, whereas it is supplied to the second raw material chamber 23b. The softening agent is added to the second papermaking raw material, and the dry paper strength agent and the wet paper strength enhancer are not added.

  The 1st papermaking raw material contains 20-100 mass% of softwood pulp with respect to the total mass of the pulp contained in this 1st papermaking raw material, and the dry paper strength agent and the wet paper strength enhancer are added. However, no softener is added.

  If the amount of softwood pulp is less than 20% by mass, the strength of the paper will be insufficient.

  Further, the dry paper strength agent is a chemical for increasing the strength of the paper in a dry state, and is added in an amount of 0.02 to 0.5% by mass based on the total mass of the pulp contained in the first papermaking raw material. . 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 papermaking raw material.

  On the other hand, the 2nd papermaking raw material contains 90-100 mass% of hardwood pulp with respect to the total mass of the pulp contained in this 2nd papermaking raw material, and the softening agent is added. However, no dry paper strength agent and wet strength agent are added.

  When the amount of hardwood pulp is less than 90% by mass, the texture is inferior.

  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 second papermaking raw material. 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.

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. Accordingly, at the boundary between the second paper layer B and the first paper layer A, the dry paper strength agent and the wet strength agent contained in the first paper layer A penetrate into the second paper layer B side. there's a possibility that. However, the side contacting the wires 12 and 13 is hardly affected by the mixing, and the ratio of the softwood pulp and the hardwood pulp contained in the first and second paper layers A and B, respectively, is 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.

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, the second paper layer B can be made smoother on the surface side of the second paper layer B, in combination with the hardwood pulp having a good touch as a main component, and added with a softener. The touch can be further improved.

Then, the reel part P _R as described above, the second sheet layer B is wound in a roll shape so that the surface. The material roll C _R are prepared two, each of the surface outside, i.e., tissue paper is made by superposing so that paper surfaces. Therefore, since the 2nd paper layer B comes on the formed tissue paper surface, smooth and soft touch can be obtained by the effect of hardwood pulp and a softening agent. On the other hand, the inner side of the tissue paper where the two base papers are in close contact with each other is the first paper layer A, so that the pulling force from the box or bag is enhanced by the effects of the softwood pulp, the dry paper strength agent and the wet strength agent. Sufficient strength can be obtained.

  Thus, depending on which side each of the two paper layers becomes in the final finished product, the roles such as strength and touch are assigned to each paper layer, and depending on the role, the additive agent for each paper layer Select. Thereby, since each paper layer does not contain a drug having a contradictory characteristic, the effect of suppressing the effect of the added drug is small, and a required addition amount is small. Therefore, the medicine is sufficiently fixed on each paper layer, and the effect of the medicine is sufficiently exhibited.

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 agent, 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 HF (hand feel value) is measured with a tissue-softness measuring device TSA (manufactured by M-Tech (Germany)), and is used as an index of texture such as flexibility and smoothness, particularly touch feeling. This numerical value must be 80 or more, and if it is lower than this numerical value, the texture is inferior, and it is not suitable.

  Each of the papers of Examples 1 to 6 shows the result that the texture such as flexibility and smoothness is good while having the required tensile strength.

  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 the texture. Comparative Example 3 corresponds to the prior art, and all the three types of softening agent, dry paper strength agent, and wet paper strength enhancer are added to the first and second papermaking raw materials. It is recognized that it is inferior to Examples 1-6. In Comparative Examples 4 and 5, which show a case where the amount of the softener added is too small and a case where it is too large, a decrease in texture and a decrease in tensile strength occur. In Comparative Examples 6 and 7, which show a case where the amount of the dry paper strength agent added is too small and a case where the amount is too large, a decrease in dry tensile strength and a decrease in texture occur. Similarly, in 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, a decrease in wet tensile strength and a decrease in texture occur.

  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 (6)

A first step of feeding a first papermaking raw material to which the dry paper strength agent and the wet strength agent are added and no softening agent is added;
A second step of supplying a second papermaking raw material to the wire of the wire part with a softener added and no dry paper strength agent and wet strength agent added;
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, 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 claim 1 or 2, comprising 90 to 100% by mass of hardwood pulp with respect to the total mass of the pulp to be produced.   4. 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.   5. 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 5 above.