JP6197621B2 - Thin paper stock preparation method, thin paper stock, thin paper manufacturing method, thin paper, and manufacturing apparatus - Google Patents

Description

  TECHNICAL FIELD The present invention relates to thin paper, particularly sanitary thin paper such as tissue paper, toilet paper, and dust paper, and relates to a preparation method of thin paper stock, thin paper stock, a method of manufacturing thin paper, thin paper and a manufacturing apparatus.

  Hygienic thin paper such as tissue paper, toilet paper, and dust paper is required to have sensory performance such as excellent softness and good touch, and strength performance that does not tear when used. As a method of improving softness, a method of adding a surfactant as a softening agent to raw pulp is known. For example, patent document 1 is disclosing the manufacturing method of the sanitary thin paper which adds a cationic surfactant in the quantity of 0.05-1 mass percent with respect to the mass of raw material pulp.

Japanese Patent No. 4044103

  However, Patent Document 1 discloses that the paper strength of thin paper decreases when the amount of the softener added is excessively increased. In recent years, demands for softness and touch are increasing, but in the method of Patent Document 1, if the sensory performance is further improved, strength performance is impaired.

  Accordingly, an object of the present invention is to provide a thin paper excellent in sensory performance such as softness while satisfying strength performance suitable for use.

The present invention for solving the above problems includes the following inventions.
(1) A method for preparing a stock for making thin paper, wherein a surfactant is added to a suspension in which raw pulp is dispersed in water, the first step of adding a cationic surfactant; And a second step of adding an amphoteric surfactant that is performed after the first step.
(2) The method for preparing thin paper stock according to (1), further comprising a stirring step of stirring the suspension between the first step and the second step.
(3) A thin paper stock prepared by the preparation method of the thin paper stock of (1) or (2).
(4) A method for producing thin paper, which includes a paper making step of making paper using the thin paper stock of (3).
(5) It further includes a preparation step for preparing the thin paper stock before the paper making step. In the preparation step, the thin paper stock is prepared by the preparation method of the thin paper stock of (1) or (2). The manufacturing method of the thin paper of (4) formed.
(6) A thin paper produced by the thin paper production method of (4) or (5).
(7) A manufacturing apparatus for preparing thin paper stock by the preparation method of (1) or (2), wherein the first means for adding a cationic surfactant and the cationic interface by the first means And a second means for adding an amphoteric surfactant after the addition of the activator.

  According to the present invention, a thin paper excellent in sensory performance such as softness can be obtained while satisfying strength performance suitable for use.

The manufacturing apparatus figure explaining the example of the paper stock preparation process which concerns on embodiment of this invention. The table | surface which shows the sensory evaluation test result of the Example of this invention.

  Hereinafter, embodiments of the thin paper and the manufacturing method thereof according to the present invention will be described. Examples of the thin paper of the present invention include sanitary thin paper such as toilet paper, tissue paper, and dust paper. The thin paper of the present invention is a paper stock preparation step for preparing a stock material which is a suspension (pulp slurry) of a raw material pulp fiber from a raw material, a raw material pulp fiber is made from the stock material, and a fiber web is formed. And a paper making process for drying the fiber web. The thin paper of the present invention is used in the stock preparation step when manufacturing the thin paper, and as a softener, a cationic surfactant and an amphoteric surfactant are added in this order and used together. Features.

[material]
The raw material which can be used for the thin paper of this invention is demonstrated. The thin paper of the present invention uses pulp as a main raw material. The raw material pulp that can be used in the present invention is not particularly limited as long as it is a fiber that can generate hydrogen bonds and can be used for papermaking. For example: mechanical pulp (MP); chemical mechanical pulp (CGP); semi-chemical pulp (SCP); kraft pulp (KP) such as hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP); soda pulp ( AP), chemical pulp (CP) such as sulfite pulp (SP), dissolving pulp (DP); synthetic pulp made from nylon, rayon, polyester, polyvinyl alcohol (PVA), etc .; deinked pulp (DIP), Waste paper pulp such as waist pulp (WP); waste pulp (TP); rag pulp made from cotton, flax, hemp, hemp, manila hemp, ramie, etc .; straw pulp, esparto pulp, bagasse pulp, bamboo pulp, kenaf pulp, etc. Raw material pulp can be appropriately selected from among stem pulp and auxiliary pulp such as bast pulp. Depending on the application of the thin paper to be produced and the required performance, one type of raw material pulp may be used, or a plurality of types of raw material pulp may be used in any ratio. The raw pulp may be unbeaten pulp, or may be beaten in whole or in part. The raw material pulp may be beaten in the stock preparation process.

  The thin paper of the present invention is characterized in that a cationic surfactant and an amphoteric surfactant are added in this order as a softening agent.

  Cationic surfactants are surfactants that ionize to have a positive (positive) charge in water. As the cationic surfactant of the present invention, for example, a quaternary ammonium salt, an amine salt, an amine, a fatty acid amide, a fatty acid ester and the like can be used.

  Zwitterionic surfactants are surfactants that can have both positive (positive) and negative (negative) charges in water. Examples of the zwitterionic surfactant of the present invention include aliphatic derivatives of secondary or tertiary amines, or heterocyclic secondary or tertiary amines containing carboxy, sulfonate, and sulfate. Etc. can be used.

  The cationic surfactant and the amphoteric surfactant can each be in the form of a polymer. Generally, only one type of cationic surfactant and amphoteric surfactant is used, but a plurality of types may be used.

  If necessary, such as dispersants, pH adjusters such as caustic soda and aqueous ammonia, antifoaming agents, preservatives, fluorescent dyes, mold release agents, water resistance agents, flow modifiers, yield improvers, paper strength enhancers, etc. Chemicals can be added.

[Manufacturing method of sanitary thin paper]
As described above, the thin paper manufacturing method of the present invention includes a stock preparation step for preparing a stock that is a suspension (pulp slurry) of a raw material pulp from a raw material, and a paper pulp made from the stock. Forming a web and drying the formed fiber web. The present invention is characterized by the stock preparation method in the stock preparation step. Each process in the manufacturing method of the thin paper based on this invention is demonstrated below.

(Paper preparation process)
The stock preparation process according to the present invention will be described.

  First, pulp fibers constituting the raw pulp are dispersed in water to obtain a suspension (pulp slurry).

  Next, a cationic surfactant is added to the suspension. Since the pulp fibers are anionic in suspension, the cationic surfactant can adsorb or bind to the pulp fibers. Due to the presence of adsorbed or bound cationic surfactant, hydrogen bonding between pulp fibers is less likely to occur, and because the spacing between pulp fibers is widened, the softness of the manufactured thin paper (final product) is improved. Conceivable.

  In order to promote the adsorption or binding of the cationic surfactant to the raw pulp fibers in the suspension, the added cationic surfactant is uniformly dispersed in the suspension. There is no particular limitation on the means for uniform dispersion. For example, stirring may be performed using any known stirrer, a similar effect may be obtained using pumping of a suspension by a pump, and pulp fibers to be performed as necessary. You may utilize the shear force etc. which arise in a disaggregation / beating process. Such treatment for uniform dispersion may be performed not only after the addition of the surfactant but also before or during the addition. Hereinafter, in this specification, terms such as “stirring”, “stirring means”, “stirring effect” are “treatment for uniform dispersion”, “means for uniform dispersion”, “uniform dispersion effect”, respectively. It shall be used synonymously.

  Next, the amphoteric surfactant is added to the suspension after the cationic surfactant is added and dispersed uniformly. Using any stirring means, the added zwitterionic surfactant is uniformly dispersed in the suspension.

  Zwitterionic surfactants can adsorb or bind to positively charged ones due to their negative charge. When the previously added cationic surfactant is adsorbed on the pulp fiber to give a positive charge to the surface thereof, the zwitterionic surfactant can be adsorbed thereto. At this time, a cationic surfactant and an amphoteric surfactant are present in layers on the surface of the pulp fiber. Such a layer structure further increases the spacing between the pulp fibers, and the softness of the manufactured thin paper (final product) is considered to increase more than when the cationic surfactant is used alone. Also, the zwitterionic surfactant can have a positive charge and can thereby adsorb or bind to anionic pulp fibers. Therefore, it is considered that the pulp fiber and the pulp fiber can be bonded via the cationic surfactant and the zwitterionic surfactant, and the strength is obtained in the manufactured thin paper (final product).

  Here, in the present invention, the order of addition of the cationic surfactant and the zwitterionic surfactant, and the stirring during the addition (treatment for uniform dispersion) are important for obtaining the effects of the present invention. is there.

  First, the importance of stirring will be described. If the surfactant is not stirred when the cationic surfactant is added, the adsorption or binding of the cationic surfactant to the pulp fibers does not occur uniformly in the suspension, so the quality of the manufactured thin paper (final product) Variation will occur. Further, if stirring is not performed, there is a possibility that the amount of the cationic surfactant that is present in the suspension without being adsorbed or bound to the pulp fiber is increased compared to the case where stirring is performed. . At this time, the zwitterionic surfactant to be added later may be adsorbed or bound to the cationic surfactant that is present in a free state, thereby forming a composite regardless of the pulp fiber. Such composites can provide softness by widening the interval between pulp fibers by being present between the pulp fibers in the thin paper as the final product. Can not be provided. In addition, such a composite may be discharged together with white water in the paper making process to be performed later, and in that case, it is considered that the effect of softening obtained with respect to the added amount of the surfactant is reduced. . Therefore, when the cationic surfactant is added to the pulp fiber suspension, stirring until the amphoteric surfactant is added is important. It is understood that stirring after the addition of the zwitterionic surfactant is also important for uniformly dispersing the zwitterionic surfactant in the suspension and causing the reaction to occur uniformly. Like.

  Next, the importance of the order of addition will be described. In the present invention in which the cationic surfactant and the zwitterionic surfactant are added in this order, the cationic surfactant and the zwitterionic surfactant are considered to exhibit the above-described behavior, and the sensory performance In addition, the effect of achieving both strength and performance can be obtained. On the other hand, when the cationic surfactant and the amphoteric surfactant are added in the reverse order of the present invention, the same effect as the present invention cannot be obtained. That is, the amphoteric surfactant generally has a lower degree of adsorption or binding to the pulp fiber than the cationic surfactant, and when the amphoteric surfactant is added first, the amphoteric surfactant is adsorbed to the pulp fiber. The proportion of the amount that is free without being bound increases. Therefore, when a cationic surfactant is added next, compared to the present invention, the ratio of formation of a complex unrelated to the pulp fibers is increased, and the pulp fibers are separated from each other by an amphoteric surfactant and a cation. It is considered that it is difficult to obtain a form that binds via an ionic surfactant. Further, when the cationic surfactant and the zwitterionic surfactant are added simultaneously, it is considered that the formation ratio of the complex unrelated to the pulp fiber is further increased, and the effect as in the present invention is still obtained. I can't. Therefore, the order of addition when the cationic surfactant and the amphoteric surfactant are added to the pulp fiber suspension is important.

  By the stock preparation process including the above steps, a stock for producing the thin paper of the present invention can be obtained.

  In the stock preparation process described above, the moisture content (pulp concentration) suitable for each step is appropriately adjusted according to a conventional method. In the paper stock preparation process, chemicals such as those exemplified above can be added to the suspension as necessary, but the materials and the addition time do not hinder the effects of the present invention described above. It is necessary to be. The stock preparation process may include a disaggregation process and / or a beating process step for unraveling or cutting the raw pulp in the suspension as necessary. There are no particular limitations on the means for the disaggregation process and the beating process, and for example, known means such as a top finer (TF) and a refiner (RF) can be used. Each addition of the cationic surfactant and the zwitterionic surfactant may be performed before, during, or after each of the disaggregation treatment and the beating treatment. It is necessary to add the zwitterionic surfactant after being sufficiently uniformly dispersed.

  One embodiment of the paper stock preparation step according to the present invention will be described with reference to the production apparatus diagram shown in FIG. This embodiment is for illustrative purposes and is not intended to limit the invention. First, raw pulp is dispersed in water with a dissolving pulper to form a suspension. The suspension is sent from the dissolving pulper to the first chest using the first pump. The suspension is then sent from the first chest to the top finalizer (TF) using a second pump. At this time, the cationic surfactant is added to the suspension by the adding means A provided immediately before the second pump. Since the pumping is performed by the second pump after this addition step, the suspension to which the cationic surfactant is added is stirred (uniformly dispersed). The suspension of raw pulp that has been disaggregated by the top finer (TF) is then beaten by the refiner (RF) and sent to the second chest. A stirring effect can also be obtained by treatment with TF and RF. In the second chest, the amphoteric surfactant is added to the suspension by the addition means B. A third pump is used to feed the suspension to the stack box or paper machine head box. Since the suspension is pumped by the third pump after this addition step, the suspension after the addition of the zwitterionic surfactant is stirred (uniform dispersion). In this way, a stock for the subsequent paper making process is manufactured.

(Paper making process)
The paper making process includes a step of making a raw material pulp from the stock obtained by the stock preparation process to form a fiber web, and a step of drying the formed fiber web. In the papermaking process of the present invention, a conventionally known papermaking method for producing thin paper can be employed. For example, thin paper can be manufactured by sequentially processing the paper stock supplied from the head box in a wire part, a press part, a dryer part, and the like. Moreover, you may perform a size press process and / or a calendar process further as needed.

Examples of the present invention will be described below.
[Example]
Softwood kraft pulp (NKP) and hardwood kraft pulp (LKP) were dispersed in water at an absolute dry mass ratio of 50%: 50% to form suspensions. To this suspension, a fatty acid-based cationic surfactant was added in an amount of 0.02% by mass based on the mass of the raw material pulp, and sufficient stirring was performed. Next, beating is performed so that the freeness down value becomes 50 cc, and an amphoteric surfactant based on an aliphatic derivative is added in an amount of 0.05% by mass with respect to the mass of the raw pulp, and further sufficient stirring is performed. The paper stock for papermaking was obtained. From this stock, thin paper having a basis weight of 14.1 g / m ² was obtained using a round net paper machine. The resulting thin paper is made up of two sheets of size 214 mm long × 218 mm wide, and 200 sets of double paper sheets are folded and combined into two so that the folded portions are alternately engaged with each other. Set.

[Reference example]
A basis weight of 14 was obtained in the same manner as in Example except that the addition amount of the amphoteric surfactant was 0% by mass with respect to the mass of the raw material pulp (that is, the amphoteric surfactant was not added). A thin paper of 1 g / m 2 was obtained. The resulting thin paper is made up of two sheets of size 214 mm long × 218 mm wide, and 200 sets of double paper sheets are folded and combined into two so that the folded portions are alternately engaged with each other. Set.

<Test content>
The sensory evaluation test was done about the thin paper of the Example and the reference example. The six test items shown below were used, and the sensory evaluation was a five-point evaluation. The average value of evaluation points by 103 testers was obtained.
(Test items)
(1) Softness: soft when removed from the tissue box.
(2) Smoothness: Smooth when taken out from the tissue box.
(3) Soft: Soft when biting nose.
(4) Moist feeling: There is a moist feel when biting the nose.
(5) Soft feeling: feels soft when you blow your nose.
(6) Skin irritation: There is little irritation to the skin when biting the nose.
(Sensory evaluation scores and standards)
5 points: I feel very much.
4 points: I feel that way.
3 points: Neither.
2 points: I don't feel that way.
1 point: I don't feel it at all.

<Test results>
The result of the sensory evaluation test is shown in the table of FIG. According to the embodiment of the present invention, the sensory performance (softness, smoothness) when taken out from a tissue box and the sensory performance (softness, moistness, softness, irritation to the skin) In any case, good results were obtained. In addition, regarding the thin paper of the example of the present invention, there was no particular tendency to be easily broken or unwound at the time of use, and it had sufficient strength performance for use.

  According to the present invention, a thin paper excellent in sensory performance such as softness while satisfying strength performance suitable for use can be obtained.

P Pump A, B Surfactant addition means

Claims (7)

A method for preparing a stock for making thin paper, wherein a surfactant is added to a suspension of raw pulp dispersed in water,
A first step of adding a cationic surfactant;
A second step of adding an amphoteric surfactant performed after the first step;
A method for preparing thin paper stock, comprising:   The method for preparing a thin paper stock according to claim 1, further comprising a stirring step of stirring the suspension between the first step and the second step.   A thin paper paper stock prepared by the thin paper stock preparation method according to claim 1 or 2.   A method for producing thin paper, comprising a paper making step of making paper using the thin paper stock according to claim 3.   The method further comprises a preparation step of preparing a thin paper stock before the paper making step, wherein the thinning paper stock is obtained by the preparation method of the thin paper stock according to claim 1 or 2 in the preparation step. The method for producing thin paper according to claim 4, wherein the thin paper is prepared. A thin paper manufactured using the thin paper sample according to claim 3 . A manufacturing apparatus for preparing thin paper stock by the preparation method according to claim 1,
A first means of adding a cationic surfactant;
A second means for adding an amphoteric surfactant after the addition of the cationic surfactant by the first means;
A manufacturing apparatus comprising:

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