JP6354647B2 - Sanitary paper and tissue paper products - Google Patents

Description

  The present invention relates to a household sanitary paper and a tissue paper product in which a plurality of sanitary papers are stacked.

  Thin sanitary paper such as tissue paper used at home requires a certain degree of tensile strength to be pulled out of a box or bag, but it touches the skin directly, so a smooth and soft texture is required. Is done. Therefore, conventionally, the blending ratio of papermaking raw materials such as softwood pulp and hardwood pulp constituting sanitary paper is adjusted, and the addition amount of chemicals such as softeners and paper strength enhancers added to these papermaking raw materials is adjusted. Attempts have been made to obtain sanitary paper that is easy to touch and excellent in strength (Patent Documents 1 to 3).

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

  However, soft and excellent touch and strong strength are contradictory properties, and even if the techniques described in Patent Documents 1 to 3 above are used, both the high strength and good touch of sanitary paper can be satisfied. It was not enough.

  Accordingly, an object of the present invention is to provide a sanitary paper that is easy to touch and excellent in strength.

  The inventor of the present invention, as a result of intensive studies on the means for solving the above problems, distinguishes the papermaking raw materials constituting the surface layer (first layer) and the back layer (second layer) of the sanitary paper, The content concentration was set to be higher than the content concentration of the softening agent in the back layer. In this way, it is possible to improve the feel of the sanitary paper by containing a large amount of softening agent on the surface layer side, and to maintain the strength of the entire sanitary paper by reducing the concentration of the softening agent on the back layer side. The inventor has conceived that the problems of the prior art can be solved based on the above knowledge, and has completed the present invention. More specifically, the present invention has the following configuration.

The first aspect of the present invention relates to sanitary paper such as tissue paper.
The sanitary paper of the present invention comprises a first surface and a second surface that is the surface opposite to the first surface. In addition, the sanitary paper of the present invention can be divided into two parts, the first layer including the first surface and the second layer including the second surface.
The softener content concentration (to the pulp dry weight ratio) in the first layer is higher than the softener content concentration (to the pulp dry weight ratio) in the second layer.

  As described above, the sanitary paper of the present invention can improve the feel and texture of the sanitary paper by containing a large amount of softening agent in the first layer. On the other hand, if a large amount of the softening agent is contained in the second layer, the strength of the entire sanitary paper is lowered. Therefore, in the present invention, the strength of the second layer is maintained by reducing the amount of the softening agent contained in the second layer or not adding the softening agent to the second layer. Thereby, it is possible to provide a well-balanced sanitary paper in which the first layer is easy to touch and the strength is maintained by the second layer.

  In the sanitary paper of the present invention, the content concentration of the softening agent in the first layer is preferably 0.04% or more. Further, the softener content in the first layer is preferably 1.5 times or more the softener content in the second layer.

  Like the said structure, the touch of a 1st layer can fully be improved by making the content density | concentration of the softening agent of a 1st layer into 0.04% or more. On the other hand, by setting the content of the softening agent in the first layer to 1.5 times or more of the content of the softening agent in the second layer, the hand of the second layer is impaired, but the strength of the second layer is increased. Can be high enough.

  In the sanitary paper of the present invention, the softener content in the first layer is preferably 0.04% or more, and it is preferable that no softener is added to the second layer.

  Like the said structure, the touch of a 1st layer can fully be improved by making the content density | concentration of the softening agent of a 1st layer into 0.04% or more. On the other hand, by not adding substantially the softening agent to the second layer, the second layer can have a sufficiently high strength although the touch of the second layer is impaired.

  In the sanitary paper of the present invention, the first papermaking raw material constituting the first layer preferably contains 90 to 100% by mass of hardwood pulp relative to the total mass of pulp contained in the first papermaking raw material. Moreover, it is preferable that the 2nd papermaking raw material which comprises a 2nd layer is 10-100 mass% of coniferous pulp with respect to the total mass of the pulp contained in this 2nd papermaking raw material.

  As in the above configuration, the sanitary paper is composed of two layers of papermaking raw materials, the first layer is a hardwood pulp main layer, and the second layer is a softwood pulp main layer. Hardwood pulp has a relatively short fiber length, is thin and supple and has good flexibility and touch, but has a characteristic that sufficient tensile strength cannot be obtained. In contrast, softwood pulp has a relatively long fiber length and is rigid and can obtain a high tensile strength, but has a property of being inferior in flexibility and touch. Therefore, in order to compensate for the mutual disadvantages of softwood pulp and hardwood pulp, taking into account these characteristics, a papermaking raw material mainly containing coniferous pulp and a papermaking raw material mainly containing hardwood pulp are used to form two layers. It is preferable to combine them.

  The second aspect of the present invention is a tissue paper product in which two or more sanitary sheets according to the first aspect described above are stacked. In the tissue paper product of the present invention, the plurality of sanitary papers are superposed such that the first surface (the surface with a high softener content) is the outer surface.

  For example, two-ply and three-ply sanitary papers are known in which a plurality of sanitary papers are stacked. As described above, the first surface of the sanitary paper is formed by the first layer to which a large amount of softening agent is added, and is excellent in touch and texture. Therefore, the first surface is directly touched to the user's skin. By using the outer surface, it is possible to provide a good feeling of use.

  ADVANTAGE OF THE INVENTION According to this invention, the sanitary paper excellent in the touch and excellent in intensity | strength can be provided.

FIG. 1 is a schematic diagram showing an example of a forming unit that can perform two-layer papermaking of papermaking raw materials. FIG. 2 is a schematic view showing an example of a method for measuring the softener-containing concentration of the surface layer and the back layer of sanitary paper. FIG. 3 is a distribution diagram in which the vertical axis represents the HF value of the tissue paper product and the horizontal axis represents the measurement result of the dry tensile strength.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. This invention is not limited to the form demonstrated below, The thing suitably changed in the range obvious to those skilled in the art from the following forms is also included.
In the present specification, “A to B” means “A to B”.

The present invention relates to a household sanitary paper used as tissue paper or toilet paper. In particular, the sanitary paper of the present invention is preferably a thin paper having a basis weight in the range of 10 to ²⁰ g / m ² . In addition, the sanitary paper of the present invention can be a two-ply product or a three-ply product or more by superimposing two or three or more sheets.

  The sanitary paper of the present invention can be manufactured using a general paper machine. A typical paper machine has 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 injected papermaking raw material (pulp) is dehydrated to form a sheet. In the wire part, the papermaking raw material whose components are prepared in advance is supplied to the forming unit in a state of containing a large amount of moisture, thereby forming a two-layered paper layer that becomes a prototype of sanitary paper. A large amount of moisture contained in the papermaking raw material is dehydrated here, and the texture of the wet paper is prepared. The specific configuration of the forming unit will be described later in detail.

  The press part is a process in which pressure is applied to the papermaking material that has been made into a sheet to further dehydrate it. In the press part, pressure is applied to the two-layer wet paper formed in the wire part and the water contained in the wet paper is squeezed out. Here, the surface of the wet paper is smoothed, and at the same time, the density of the pulp component constituting the main part of the wet paper is increased to form a strong wet paper.

  The dryer part is a process in which a sheet of papermaking raw material is introduced into the dryer and completely dried by applying heat. In the dry part, excess water is forcibly evaporated by heating the wet paper that has passed through the press part with a Yankee dryer. As a result, paper obtained by drying the wet paper is obtained. The paper wound around the mirror roll of the Yankee dryer and dried is peeled off from the surface of the mirror roll while being creped by a creping doctor, and is transported to a subsequent calendar part.

  The calendar part is a process in which the surface of the sheet after drying is stretched while being pressed to smooth the surface of the sheet. In other words, in the calendar part, the paper in a nearly completed state is introduced between a pair of calendar rolls, thereby smoothing the surface of the paper and increasing its density.

  The reel part is a step of winding a long paper obtained through each step to form a roll body in which the paper is wound in multiple layers. At the reel part, the finished paper, that is, the base paper of sanitary paper that becomes a piece of tissue paper, is wound up in a roll. After that, two sanitary paper rolls obtained through the above-mentioned process are prepared, and they are stacked and cut in a separate process, so that two sets of tissue paper products (2-ply) Can be obtained. Also, by preparing three rolls of sanitary paper base paper, it is possible to obtain a set of three (three ply) tissue paper products.

  Next, the forming unit installed in the wire part will be described in detail with reference to FIG. As shown in FIG. 1, the forming unit 11 includes a forming roll 18, endless inner wires 12 and outer wires 13, and a plurality of guide rolls 21. A driving force applied to a driving roll (not shown) is transmitted to the forming roll 18 and the guide roll 21. Then, when the forming roll 18 and the guide roll 21 rotate synchronously, the inner wire 12 and the outer wire 13 wound so as to be in contact with a part of the peripheral surface of the forming roll 18 travel at the same speed. As a result, an initial forming region Z is formed in a region between the inner wire 12 and the outer wire 13 wound around the peripheral surface of the forming roll 18. The initial forming area Z is a curved area for paper making and initial dehydration of the paper layer C, and is formed between the inner wire 12 and the outer wire 13.

  As shown in FIG. 1, the forming unit 11 further includes a head box 19. The head box 19 is an apparatus for simultaneously supplying two types of papermaking materials toward the curved initial forming region Z. Inside the head box 19, two raw material chambers 23 a and 23 b for introducing two types of papermaking raw materials to the discharge port are provided with a partition wall 24 therebetween. A first papermaking raw material prepared by a preparation facility (not shown) is supplied to the first raw material chamber 23a. Similarly, a second papermaking raw material adjusted by a preparation facility (not shown) is supplied to the second raw material chamber 23b. The first papermaking raw material in the first raw material chamber 23a and the second papermaking raw material in the second raw material chamber 23b are separated by the partition wall 24 and guided to the discharge port without being mixed with each other. . As described above, when two types of papermaking raw materials are simultaneously ejected from the head box 19, the first paper layer A mainly composed of the first papermaking raw material is formed on the outer wire 13 side, and the first paper layer A is formed on the inner wire 12 side. A second paper layer B mainly composed of the second papermaking raw material is formed. Then, the paper layer A and the paper layer B are integrated to form a paper layer (wet paper) in a two-layered state. Thereafter, the paper layer is conveyed from the initial forming area Z toward the subsequent press part via the inner wire 12.

  By using the head box 19 configured as described above, it is possible to manufacture sanitary paper including the first layer A mainly composed of the first papermaking raw material and the second layer B mainly composed of the second papermaking raw material. Then, by adjusting the first papermaking raw material and the second papermaking raw material to different components, the physical property values and other properties of the first layer A (surface layer) and the second layer B (back layer) of the sanitary paper are different. Can be made. For example, in the first papermaking raw material and the second papermaking raw material, the blending ratio of softwood pulp and hardwood pulp, the amount of softener and paper strength agent added, whether or not the pulp fibers are beaten, or the load of beating Various components and conditions such as amount can be varied. As a result, the physical properties of the front and back layers of the sanitary paper can be freely adjusted to some extent independently. As the physical properties of the sanitary paper, the fiber length, tensile strength, HF value (hand feel value), etc. of the constituent fibers constituting the sanitary paper can be given as representative examples.

  For example, when it comes to sanitary papermaking raw materials, softwood pulp has the characteristics that the fiber length is relatively long and stiff and high tensile strength is obtained, but the flexibility and the hand are inferior. Hardwood pulp, on the other hand, has a relatively short fiber length, is thin and flexible, has good flexibility and touch, but has a low tensile strength. For this reason, in order to increase the strength of sanitary paper, the blending ratio of softwood pulp may be increased. On the other hand, in order to improve the feel of sanitary paper, the blending ratio of hardwood pulp may be increased.

  As for chemicals added to papermaking raw materials, adding a paper strength enhancer such as a dry paper strength agent or a wet paper strength agent to papermaking materials has the effect of increasing the strength of sanitary paper. And the property that the smoothness decreases. In contrast, the addition of a softening agent to the papermaking raw material has the effect of improving the flexibility and feel of the sanitary paper, but has the property of reducing the strength of the sanitary paper. For this reason, a paper strength enhancer may be added to increase the strength of the sanitary paper, and a softener may be added to improve the touch of the sanitary paper.

  Also, beating the pulp fibers (conifer pulp, hardwood pulp, etc.) used as the papermaking raw material shortens the fiber length. For this reason, in order to increase the average fiber length of the constituent fibers of the sanitary paper, it is not necessary to beat the pulp fibers. Further, in order to shorten the average value of the fiber lengths of the constituent fibers of the sanitary paper, the pulp fibers may be beaten or the beating load may be increased.

  As described above, the ingredients of the papermaking material affect the physical properties such as the strength of the sanitary paper or the touch. Factors that affect the physical properties of sanitary paper include the ratio of pulp fiber, the presence or absence of chemicals, the presence or absence of beating, and the presence or absence of beating work. The physical property value changes. Further, as described above, when sanitary paper is in a two-layered state, and the first papermaking raw material constituting the surface layer and the second papermaking raw material constituting the back layer are adjusted independently, The conditions for preparing the papermaking raw material are further complicated.

  Accordingly, the inventors of the present invention have repeatedly studied focusing on the softener added to the papermaking raw material of sanitary paper. And in sanitary paper with two layers, the softener content in the front layer (first layer) including the front surface (first surface) and the back layer (second layer) including the back surface (second surface) Specifically, the concentration of softener in the surface layer (first surface) (vs. pulp dry weight ratio) and the concentration of softener in the back layer (second layer) (vs. pulp dry weight) It was found that the strength can be maintained at a high level and the touch can be improved by making the ratio higher than the ratio. In particular, the softener content in the surface layer is preferably 0.04% or more and 1.5 times or more the softener content in the back layer. Furthermore, it is preferable that the softener is not substantially added to the back layer.

  As the softening agent here, a known one used in papermaking can be appropriately employed. As the softening agent, for example, known ones such as anionic surfactants, nonionic surfactants, cationic surfactants, and zwitterionic surfactants may be used alone or in admixture of two or more. preferable. Examples of the anionic surfactant include carboxylate-based, sulfonate-based, sulfate ester-based, and phosphate ester-based surfactants. Nonionic surfactants include polyhydric alcohol monofatty acid esters such as sorbitan fatty acid ester, diethylene glycol monostearate, diethylene glycol monooleate, glycerin monostearate, glycerin monooleate, and propylene glycol monostearate. be able to. Examples of cationic surfactants include quaternary ammonium salts, amine salts, and amines. Examples of the zwitterionic surfactant include fatty acid derivatives of secondary or tertiary amines containing carboxy, sulfonate, sulfate, and fatty acid derivatives of heterocyclic secondary or tertiary amines. it can.

[Measurement method of softener content (vs. pulp dry weight ratio)]
Here, the softener content (on the basis of pulp dry weight) in the surface layer and back layer of sanitary paper can be measured by the following method. An overview of this measurement method is shown in FIG.
[1] Divide tissue paper products (two-layer) into sanitary paper, one side of the product, the side facing the outside is the surface of the sanitary paper, and the side facing the inside is the back side of the sanitary paper And
[2] The sanitary paper made into one sheet in [1] is cut into a test piece of 100 mm wide by 100 mm long, and the weight of the test piece is measured.
[3] As shown in FIG. 2 (a), an electrical insulating tape manufactured by 3M was fixed to the test bench with gum tape or the like with the adhesive surface facing upward, and the test piece obtained in [2] should be free from wrinkles. Affix to the electrical insulation tape.
[4] As shown in FIG. 2 (b), another electrical insulating tape is applied on the test piece attached to the electrical insulating tape in [3], and the test piece paper piece is attached with the two tapes. Put in a pinched state. At this time, be careful not to let air enter between the test piece and the electrical insulating tape.
[5] Adhere the specimen and the electrical insulating tape well using a roller.
[6] As shown in FIG. 2 (c), when the electrical insulating tape affixed on the test piece in [4] is peeled off, the test paper is divided into two layers, a surface layer and a back layer.
[7] The two electrical insulating tapes obtained in [6] are cut out to 100 mm × 100 mm according to the size of the test piece, and the electrical insulating tape to which the surface layer of the test piece is adhered and the back layer of the test piece Measure the weight of the electrical insulating tape with the attached (weight including the tape).
[8] The test piece divided into two layers (attached to the electrical insulating tape) is soaked in ion-exchanged water, and the fibers are removed from each tape. Evaporate to obtain dry fiber.
[9] The dried fiber obtained in [8] is pulverized by a pulverizer (MM301 manufactured by Lecce).
[10] The fiber after pulverization obtained in [9] using a pyrolysis gas chromatograph mass spectrometer (pyrolysis apparatus: PY-2020D manufactured by Frontier Laboratories, gas chromatograph mass spectrometer: 5973N manufactured by Agilent Technologies) For the minute, the concentration of the softener component (to the pulp dry weight ratio) was measured. The measurement was performed twice for each test piece, and the average value was defined as the softener concentration (vs. pulp dry weight ratio).
[Remarks]
A standard sample is prepared in advance when measuring the content of softener component in each specimen (ratio to pulp dry weight). The standard sample was prepared by adding a softening agent to dry filter paper (manufactured by Advantech Co., Ltd.) so as to have a predetermined softening agent-containing concentration (to the pulp dry weight ratio), drying, and then pulverizing with a pulverizer. After that, for a standard sample prepared in advance, a calibration curve (softening factor) was calculated from the known softener content concentration (ratio to pulp dry weight) and the peak area of the softening agent component detected by the pyrolysis gas chromatograph mass spectrometer. Agent concentration = coefficient a × peak area). Subsequently, the peak area of the softener component of each test piece was measured and substituted into the above-mentioned calibration curve equation, and the softener-containing concentration (weight ratio of pulp dry weight) of each test piece was calculated.
[important point]
When the test piece is divided in [6] above, the weight ratio of the surface layer and the back layer satisfies the following conditions.
-Surface layer / back layer (weight ratio) = 40 / 60-60 / 40
Only those satisfying the above conditions are judged to be appropriate specimens. If the above conditions are not satisfied, the measurement procedure is repeated.
In addition, the ratio (weight ratio) of the surface layer divided into two layers and the back layer is calculated by the following formula.
-Ratio of surface layer = ([surface layer + tape weight]-[tape weight]) / (weight of test piece before division)
-Ratio of back layer = 1-Ratio of surface layer

In the specification of the present application, the “front surface” means a surface of the sanitary paper that is assumed to directly touch the user's skin, and the “back surface” means a surface opposite to the front surface. For example, in a two-ply tissue paper product in which two sanitary papers are stacked, the surface corresponding to the outer surface that contacts the user's skin corresponds to the surface of the sanitary paper, and the inner surface that does not contact the user's skin corresponds to the sanitary paper. It corresponds to the back side. In other words, a two-ply tissue paper product is a stack of sanitary paper with the backs facing each other.
The “surface layer” means a layer including the surface among the sanitary paper layers divided in accordance with the procedure [6]. Similarly, the “back layer” means a layer including the back side of the sanitary paper layers divided according to the above procedure [6].

  As described above, by increasing the content of the softening agent in the surface layer (first layer) of the sanitary paper, the feel and texture of the sanitary paper can be improved. For example, the softener content in the surface layer is preferably 0.04 to 0.10% or 0.15 to 0.30%. When the content of the softening agent in the surface layer is less than 0.04%, it is impossible to give the user a feeling that the touch and texture are good. If the concentration of the softening agent in the surface layer exceeds 0.30%, the strength of the surface layer of the sanitary paper is remarkably lowered, and there is a concern that paper dust is likely to be generated during drying. For this reason, it is suitable for the content concentration of the softening agent in the surface layer to be in the range of 0.04 to 0.30%.

  In particular, the softener content in the surface layer of the sanitary paper is higher than the softener content in the back layer (second layer). For example, the softener content in the surface layer is preferably 1.5 times, 1.6 times, or 1.8 times the surface layer. In this way, by increasing the difference in the softener-containing concentration between the surface layer and the back layer, it is possible to increase the tensile strength of the entire sanitary paper while maintaining the touch of the surface layer. That is, by lowering the content of the softening agent in the back layer of the sanitary paper, the bonding strength between the constituent fibers is increased, so that the tensile strength can be increased. In this way, in the present invention, the softener content in the surface layer is increased to improve the feel, and the softener content in the back layer is decreased to maintain the overall strength of the sanitary paper. Note that the sanitary paper according to the present invention is not excellent in touch and texture on the back surface compared to the front surface. However, since the back side is not supposed to touch the skin directly to the user, even if the touch of the back side is dropped, the quality of the sanitary paper as a whole, especially the quality of tissue paper products of 2 plies or more Will not be greatly impaired. Thereby, it is possible to provide sanitary paper and tissue paper products that are easy to touch and excellent in strength.

  The content of the softening agent in the back layer is not particularly limited as long as it is less than 2/3 as compared with the surface. For example, 0 to 0.03% or 0 to 0.15% is preferable. When the content of the softening agent in the back layer exceeds 0.15%, the tensile strength of the back layer becomes weak, and the strength of the sanitary paper as a whole cannot be maintained. Therefore, the softener content in the back layer is preferably in the range of 0 to 0.15%.

  As described above, if the condition that the content of the softening agent in the surface layer is higher than that in the back layer is satisfied, a sanitary paper having a good touch and excellent strength can be obtained. In order to obtain such sanitary paper, a known manufacturing method and papermaking raw material preparation conditions may be adopted as appropriate to satisfy the above conditions.

  Examples of cellulose fiber raw materials for forming sanitary paper include chemical pulps such as kraft pulp (KP), sulfite pulp (SP) and soda pulp (AP), semi-chemical pulp (SCP), and chemiground wood pulp (CGP). Such as semi-chemical pulp such as wood pulp (GP), thermomechanical pulp (TMP, BCTMP), etc., or non-wood pulp made from straw, cocoon, hemp, kenaf, etc., cotton linter, cotton lint, etc. Examples include cotton-based pulp and deinked pulp made from waste paper. These may be used alone or in combination of two or more.

  For example, in the sanitary paper of the present invention, it is preferable that the first papermaking raw material constituting the surface layer is mainly composed of hardwood pulp. For example, it is preferable that the 1st papermaking raw material which comprises a surface layer contains 90-100 mass% of hardwood pulp with respect to the total mass of the pulp contained in this 1st papermaking raw material. On the other hand, it is preferable that the 2nd papermaking raw material which comprises a back layer contains 20-100 mass% of coniferous pulp with respect to the gross mass of the pulp contained in this 2nd papermaking raw material, Especially 20-80. It is preferable to contain 20 mass% or 20-70 mass%.

  In addition, beaten pulp fibers used as raw materials for papermaking (softwood pulp, hardwood pulp, etc.) can strengthen the bond between fibers and increase the tensile strength, but on the other hand, they become stiff so that the sanitary paper has flexibility and touch. Will be reduced. For this reason, when emphasizing the touch of sanitary paper, unbeaten pulp fibers may be used as the papermaking raw material.

  In addition, for example, a dry paper strength agent or a wet paper strength enhancer can be added to a papermaking raw material for sanitary paper. A dry paper strength agent is a chemical for increasing the strength of paper in a dry state. As the dry paper strength agent, for example, known ones such as cationized starch, polyacrylamide, and carboxymethylcellulose (CMC) can be used alone or in admixture of two or more. The wet paper strength enhancer is a drug for suppressing a decrease in paper strength when the paper gets wet. As the wet paper strength enhancer, for example, known materials such as polyamide / epichlorohydrin resin, urea resin, melamine resin, and thermal crosslinkability imparting polyacrylamide (PAM) can be used alone or in combination of two or more. .

  For example, in the sanitary paper of the present invention, it is preferable to add a softener only to the first papermaking raw material mainly composed of hardwood pulp constituting the surface layer. The softening agent may be added at 0.01 to 0.50 mass% with respect to the total mass of the pulp contained in the first papermaking raw material. In particular, the addition amount of the softening agent is preferably 0.015 to 0.20% by mass. On the other hand, it is preferable not to add a softening agent to the second papermaking raw material mainly composed of softwood pulp constituting the back layer. However, there is no problem even if a softening agent of 1/10 or less of the first papermaking raw material is added to the second papermaking raw material.

  Further, in the sanitary paper of the present invention, a paper strength enhancer such as a wet paper strength agent or a dry strength paper may be added to both or either one of the surface layer and the back layer. For example, the paper strength enhancer may be added at 0.01 to 0.15 mass% or 0.05 to 0.10 mass% with respect to the total mass of pulp contained in the papermaking raw material.

  Further, for example, the surface of the sanitary paper is preferably a surface (yankee surface) in contact with the mirror surface roll of the Yankee dryer in the above-described dryer part for drying the wet paper. On the other hand, the back surface of the sanitary paper is a surface that is not in contact with the mirror roll of the Yankee dryer (non-yankee surface). As described above, the HF value of the surface that becomes the Yankee surface is improved. On the other hand, the back surface that has become a non-Yankee surface has a lower HF value than the Yankee surface.

  As described above, if sanitary paper that satisfies the condition that the softener content in the surface layer is higher than that of the back layer, the touch is better than sanitary paper that does not satisfy either or both of these conditions. Sanitary paper with excellent strength can be obtained. Examples for confirming the effects of the present invention will be described below.

  Table 1 shows a list of various measurement results related to the examples and comparative examples of the present invention. FIG. 3 is a distribution diagram in which the horizontal axis represents the geometric mean value of the dry tensile strength of the tissue paper product, and the vertical axis represents the HF value of the tissue paper product.

  In this example and comparative example, a two-ply tissue paper product was targeted. Two-ply tissue paper products were peeled off one by one to make individual sanitary paper. As for the sanitary paper, the surface corresponding to the outer surface of the tissue paper product was the front surface (first surface), and the surface corresponding to the inner surface of the tissue paper product was the back surface (second surface).

In Example 1 of the present invention, 40% of hardwood kraft pulp (hereinafter referred to as “LBKP”) is blended in the first papermaking material constituting the front side of the whole pulp slurry (100%), and the back side is constituted. 50% of softwood kraft pulp (hereinafter referred to as “NBKP”) and 10% of LBKP were added to the papermaking raw material No. 2. That is, the weight ratio of the first papermaking raw material to the second papermaking raw material was about 4: 6. The first papermaking material was LBKP 100%, and the second papermaking material was LBKP 17% and NBKP 83%. In addition, a wet paper strength agent is added to each of the first papermaking raw material and the second papermaking raw material in the pulp slurry by 0.09% by weight (ratio to the weight of pulp), and the softening agent is added to the first papermaking raw material. Only 0.04% by weight (ratio to pulp weight) was added. The additive chemical used was a wet paper strength agent made by Arakawa Chemical Industries, Ltd. and a softener made by Seiko PMC Co., Ltd. The pulp slurry thus prepared was made using a two-layer crescent former to obtain a sanitary paper having a basis weight of 11.2 g / m ² . The sanitary paper has a Yankee surface (surface in contact with the Yankee dryer mirror roll) and a non-yankee surface (surface not in contact with the Yankee dryer mirror roll).

In Example 2 of the present invention, 50% of hardwood kraft pulp (hereinafter “LBKP”) is blended with the first papermaking material constituting the front side of the whole pulp slurry (100%), and the back side is constituted. 10% of softwood kraft pulp (hereinafter referred to as “NBKP”) and 40% of LBKP were added to the papermaking raw material No. 2. That is, the weight ratio of the first papermaking raw material to the second papermaking raw material was about 5: 5. The first papermaking material was LBKP 100%, and the second papermaking material was LBKP 80% and NBKP 20%. In addition, a wet paper strength agent is added to each of the first papermaking raw material and the second papermaking raw material in the pulp slurry by 0.09% by weight (ratio to the weight of pulp), and the softening agent is added to the first papermaking raw material. Only 0.20% by weight (weight ratio of pulp) was added. The same wet paper strength agent and softening agent as in Example 1 were used. The pulp slurry thus prepared was made using a two-layer paper crescent former to obtain sanitary paper having a basis weight of 14.0 g / m ² . The sanitary paper has a Yankee surface (surface in contact with the Yankee dryer mirror roll) and a non-yankee surface (surface not in contact with the Yankee dryer mirror roll).

  In Comparative Example 1, the softening agent was 0.02% by weight (ratio to the weight of pulp) for each of the first papermaking raw material constituting the front surface side and the second papermaking raw material constituting the back surface side. 0.04% by weight was added. In Comparative Example 1, the total amount of softening agent added is 0.04% by weight, which is the same as Example 1. However, Comparative Example 1 is only for the first papermaking raw material in that the softening agent is added to each of the first papermaking raw material and the second papermaking raw material by 0.02% by weight (ratio to pulp weight). Different from Example 1 with the addition of 0.04 wt% softener. The other papermaking conditions in Comparative Example 1 were exactly the same as those in Example 1.

  In Comparative Example 2, the softening agent was added in an amount of 0.10% by weight (ratio to pulp weight) with respect to each of the first papermaking raw material constituting the front side and the second papermaking raw material constituting the back side. 20% by weight was added. In Comparative Example 2, the total amount of the softening agent added is 0.20% by weight, which is the same as Example 2. However, Comparative Example 2 is different from the first papermaking raw material only in that the softener is added to each of the first papermaking raw material and the second papermaking raw material by 0.10% by weight (ratio to the weight of pulp). This is different from Example 2 in which 0.20% by weight softening agent was added. The other papermaking conditions in Comparative Example 2 were the same as those in Example 2.

  About each of above-mentioned Example 1, Example 2, Comparative Example 1, and Comparative Example 2, the content density | concentration of the softening agent in the surface layer and back layer of sanitary paper, the basic weight (1 ply) of tissue paper products, thickness ( 1 ply), HF value, and dry tensile strength were measured.

  Here, the content and weight ratio of the softening agent in the surface layer and the back layer of the sanitary paper were measured according to the above-described [Measurement method of softening agent content concentration (weight ratio of pulp dry weight)]. The softener content in all layers of sanitary paper was measured by the following method. That is, about 200 to 300 μg of tissue is cut out, and using a pyrolysis gas chromatograph mass spectrometer (pyrolysis apparatus: PY-2020D manufactured by Frontier Laboratories, gas chromatograph mass spectrometer: 5973N manufactured by Agilent Technologies), a softener-containing concentration (Vs. pulp) was measured. Each test piece was measured twice, and the average value was defined as the softener-containing concentration (vs. pulp).

  The measured value of the basis weight indicates the measured value of one ply (that is, individual sanitary paper) constituting the tissue paper product. The basis weight was measured in accordance with JIS P8124.

  The thickness measurement value indicates the measurement value of one ply (that is, individual sanitary paper) constituting the tissue paper product. Thickness is measured at a speed of 1 mm or less per second using a thickness gauge (manufactured by Hibridge Corporation) in an environment compliant with ISO 187 (23 ° C ± 1 ° C, humidity 50% (± 2%)). I read the value when I lowered it. In addition, the measurement measured eight samples one by one, and averaged the acquired eight thicknesses.

The HF value of tissue paper products is the value measured with 2 plies. The HF value is an objective index that comprehensively shows factors such as touch feeling of sanitary paper, texture, smoothness, suppleness, and volume. The HF value indicates that the higher the numerical value, the better the touch feeling. In this example, those having an HF value lower than 80 were judged to be ineligible because the feel and texture were poor. The measurement conditions for the HF value of tissue paper products are as follows.
[Measurement condition of HF value]
・ Measuring machine: tissue softness analyzer ・ Manufacturer: Emtec Electronic GmbH (Germany)
・ Japan agency: Nippon Luft Co., Ltd. ・ Standard sample shape: Sample cut into a circle with a diameter of about 112.8 mm ・ Measurement environment: Environment conforming to ISO 187 (23 ° C. ± 1 ° C., humidity 50% (± 2%))
・ Measurement conditions: 1 point calibration with standard sample (emtec ref.2X (nn.n)) according to the attached instruction, and the algorithm is set to facial II. The calculation software used was emtec measurement system Ver.2.98.
For the sample installed on the sample stage, the vibration frequency when the rotor with blade is pushed from above with an indentation pressure of 100 mN and rotated at a rotation speed of 2.0 (/ sec), and the sample installed on the sample stage The HF value (hand feel value) can be obtained from the amount of deformation in the vertical direction when the bladed rotor is pushed from above with a pushing pressure of 100 mN and 600 mN without rotating the bladed rotor. The measurement is performed 8 times for each sample, and the average value of 8 acquired HF values is excluded from the average value exceeding ± 2 x [standard deviation of the average value]. To get.

  The tissue paper product was dried with a two-ply tensile strength. The dry tensile strength was measured according to JIS P8113. When the geometric average of the dry tensile strength in the machine direction and the transverse direction is less than 1.5 [N / 25 mm], troubles such as paper breakage occur during paper making. For this reason, as the measurement result of the dry tensile strength, those having a geometric average of 1.5 [N / 25 mm] or less were considered inappropriate.

  In Example 1 and Example 2, although the softener is not added to the back layer, the softener is contained in the back layer because the raw materials of the first layer and the second layer are on the wire. This is because the raw material filtered by the wire (= white water) is returned to the raw material preparation system and used to dilute the paper raw materials for the front and back layers. Therefore, even if no softening agent is added to the back layer, the back layer contains white water, so the softening agent is also detected from the back layer. In Examples 1 and 2 and Comparative Examples 1 and 2, the concentration of the softener in all layers is higher than the softener concentration (weight ratio of pulp) added during papermaking raw material preparation. This is because the filtered raw material (= white water) is returned to the raw material preparation system and used to dilute the papermaking raw materials for the front and back layers.

  First, Example 1 and Comparative Example 1 are compared. As shown in Table 1 above, the sanitary paper of Example 1 has a softener content concentration of 0.05% in the surface layer and a softener content concentration in the back layer of 0.03%. The content concentration is about 0.02% higher. In this case, Example 1 had an HF value of 80.8 and a dry tensile strength (geometric mean) of 2.44 N / 25 mm, which was sufficiently excellent in terms of feel and strength. On the other hand, as shown in Table 1, the sanitary paper of Comparative Example 1 has a softener content concentration of 0.03% in the surface layer and a softener content concentration in the back layer of 0.03%. There was no difference between the softener content and the backside. In this case, Comparative Example 1 has a dry tensile strength (geometric mean) of 2.27 N / 25 mm, which is sufficient in terms of strength, but the HF value is less than 80.0, and is a product in terms of hand feeling. Was not eligible.

  Interestingly, when Example 1 and Comparative Example 1 are compared, the concentration of the softening agent remaining in all layers of the sanitary paper is obtained even though the same amount of softening agent is added to the papermaking raw material. As a result, it is 0.08% in Example 1, and 0.06% in Comparative Example 1. Thus, in Example 1, compared with Comparative Example 1, the fixing rate of the softening agent was as high as about 30%.

  Next, Example 2 and Comparative Example 2 are compared. In Example 2 and Comparative Example 2, compared with Example 1 and Comparative Example 1, respectively, the total amount of the softening agent added to the papermaking raw material is increased. As shown in Table 1 above, the sanitary paper of Example 2 has a softener content concentration of 0.17% in the surface layer and a softener content concentration in the back layer of 0.09%. The content concentration is about 0.08% higher. In this case, Example 2 had an HF value of 85.2 and a dry tensile strength (geometric average) of 1.59 N / 25 mm, which was sufficiently excellent in terms of feel and strength. On the other hand, as shown in Table 1, the sanitary paper of Comparative Example 2 has a softener content concentration of 0.10% in the surface layer and a softener content concentration in the back layer of 0.12%. There was almost no difference between the softener content. In this case, in Comparative Example 2, although the HF value is 81.4, which is sufficient in terms of touch feeling, the dry tensile strength (geometric mean) is less than 1.42 N / 25 mm, and trouble occurs during papermaking. The product was not eligible as a product.

  Interestingly, when Example 2 and Comparative Example 2 are compared, the concentration of the softening agent remaining in all layers of the sanitary paper is obtained even though the same amount of softening agent is added to the papermaking raw material. As a result, it is 0.26% in Example 2 and 0.22% in Comparative Example 2. Thus, in Example 2, compared with Comparative Example 2, the fixing rate of the softening agent was about 20% higher.

  As described above, it was confirmed that the sanitary paper is excellent in touch and has sufficient strength by making the softener content in the surface layer higher than the softener content in the back layer.

  As mentioned above, in this specification, in order to express the content of the present invention, the embodiment and the example of the present invention were described. However, the present invention is not limited to the above-described embodiments and examples, but includes modifications and improvements obvious to those skilled in the art based on the matters described in this specification.

  The present invention can be suitably used in the manufacturing industry of household sanitary paper and tissue paper products.

DESCRIPTION OF SYMBOLS 11 ... Forming unit 12 ... Inner wire 13 ... Outer wire 18 ... Forming roll 19 ... Head box 21 ... Guide roll 23a ... First raw material chamber 23b ... Second raw material chamber 24 ... Partition wall A ... First paper layer B ... second paper layer C ... paper layer Z ... initial forming area

Claims (4)

A sanitary paper having a first side and a second side opposite to the first side,
When the sanitary paper is divided into a first layer including the first surface and a second layer including the second surface, the content of softener in the first layer (ratio to pulp dry weight) is the concentration of the softener in the second layer (the pulp dry weight) rather higher than,
The first papermaking raw material constituting the first layer includes 90 to 100% by mass of hardwood pulp with respect to the total mass of pulp contained in the first papermaking raw material,
The second papermaking material constituting the second layer is sanitary paper containing 10 to 100 mass% of softwood pulp with respect to the total mass of pulp contained in the second papermaking material . The softener content in the first layer is 0.04% or more,
The sanitary paper according to claim 1, wherein the content concentration of the softening agent in the first layer is 1.5 times or more the content concentration of the softening agent in the second layer. The softener content in the first layer is 0.04% or more,
The sanitary paper according to claim 1 or 2, wherein the softening agent is not added to the second layer. A tissue paper product obtained by stacking two or more sanitary sheets according to any one of claims 1 to 3 ,
A tissue paper product in which the sanitary paper is overlaid so that the first surface is the outer surface.

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