TWI500838B - Tissue papers for household use - Google Patents

Description

Household leaf paper

The present invention relates to household tissue paper for tissue paper, paper towels, and the like, such as toilet paper, cosmetic paper, and the like, and more particularly to household thin leaf paper which is soft and has good hand touch and excellent strength. .

In the past, the pulp used for household tissue paper, such as tissue paper, paper towel, and the like, is made of chemical pulp obtained by steaming wood chips obtained from broadleaf trees and conifers. Slushed pulp in the mud state, dry pulp obtained by dehydrating and drying the soft mud pulp, or deinked old paper pulp obtained by deinking the old paper, etc. These pulps are used singly or in combination with the quality design in the state of unbleached pulp or bleached pulp, or in the state of pulp which has not been beaten or has been beaten.

The technique of how to improve the softness and hand touch of important quality indexes of facial tissue has been studied in the past, and various proposals have been made, for example, by appropriately selecting: the type of pulp to be laminated, A laminated paper having a ratio of use thereof and a method for producing the same (Patent Document 1 and Patent Document 2), a long-wire paper machine, a short-wire paper machine, a double-line paper machine, a rotary paper-type paper machine, or the like, or A softening agent for paper, for example, a fatty acid ester-based softening agent (Patent Document 3), a fourth-order ammonium salt-type cationic surfactant (Patent Document 4), a urethane or a salt thereof, or a cation Additives such as a compound (Patent Document 5), a non-cationic surfactant (Patent Document 6, Patent Document 7), a polyphosphate (Patent Document 8), and a polyoxane (Patent Document 9, Patent Document 10) In the soft muddy pulp, the method of improving the smoothness of the soft muddy pulp itself, thereby making the hand touch feeling good and soft; further, after the pulp is concentrated, the fiber is mechanically mixed and stirred to make the fiber Bending softening Patent Document 11, Patent Document 12) and the like.

The above-mentioned method of adding a drug sometimes has a good softening effect, but since the foaming property is large, there is a concern that the papermaking operation itself is inconvenient, and sometimes the paper strength and water absorption are lowered. The problem. Further, in the case where the fiber is bent by mechanical treatment, it is necessary to increase the amount of work for concentrating the raw material, and thus it is disadvantageous in terms of the energy source, and these are problems.

In addition, in order to enhance the wetting strength of the facial tissue, a moist paper strength enhancer such as polyamine, polyamine or epoxy resin is mainly used, but the facial tissue itself becomes relatively straight, in terms of softness and hand touch. In terms of it, it will have a negative impact, which is the problem.

In addition, in order to improve the smoothness of the surface, in the past, after a paper machine, one or two sets of calenders consisting of a pair of fully ground chill rolls and metal rolls are used. . However, with such a calender, in order to improve the smoothness and thereby increase the line pressure, there is a problem that the thickness becomes thin and becomes straight and the hand feel becomes hard.

[Patent Document 1] Japanese Patent Laid-Open No. 54-46914

[Patent Document 2] Unexamined Japanese Patent Publication No. 4-66992

[Patent Document 3] U.S. Patent No. 3,296,065

[Patent Document 4] Japanese Patent Laid-Open No. 48-22701

[Patent Document 5] Japanese Laid-Open Patent Publication No. 60-139897

[Patent Document 6] Japanese Patent Laid-Open No. Hei 2-99690

[Patent Document 7] Japanese Patent Laid-Open No. 2-99691

[Patent Document 8] Japanese Patent Laid-Open No. 2-36288

[Patent Document 9] Japanese Patent Laid-Open No. Hei 2-224626

[Patent Document 10] Japanese Patent Laid-Open No. 3-900

[Patent Document 11] Japanese Patent Laid-Open Publication No. 5-23262

[Patent Document 12] Japanese Patent Laid-Open No. Hei 6-14848

An object of the present invention is to provide a household thin leaf paper which is soft and has a good hand touch and has excellent strength.

As a result of continuous research, the present inventors have found that a pulp obtained by applying a pulping force generated by breaking a bubble generated by a cavitation phenomenon to a pulp fiber can be soft and has a good touch. At the same time, the invention of the thin leaf paper for household use having excellent strength has completed the present invention.

According to the present invention, it is possible to obtain a household leaf paper which is soft and has a good hand touch and has excellent strength.

[Best way to implement the invention]

The household thin leaf paper of the present invention is characterized in that it contains pulp obtained by applying a punching force generated when a bubble generated by cavitation occurs at the time of cracking to a pulp fiber. In the following description, the "crushing force generated by the cavitation generated by the cavitation phenomenon is applied to the pulp fiber" is called "cavitation treatment".

The pulp which is the object of the cavitation treatment of the present invention is not particularly limited, and a chemical pulp (bleached kraft pulp (NBKP) of coniferous tree or a chemical pulp obtained by distilling a lignocellulosic material with an alkaline distilling solution may be used. Unbleached Kraft Pulp (NUKP), Hardwood Bleached Kraft Pulp (LBKP), Mechanical Pulp (Grated Wood Pulp (GP), Mechanical Fine Ground Pulp (RGP), Thermomechanical Treatment Pulp (TMP), Chemical Thermomechanical Treatment of Pulp (CTMP), etc., deinked pulp (DIP), and the like. For chemical pulp, kraft pulp, polysulfide pulp, sodium alkali pulp, alkaline sulfite pulp, sodium carbonate alkali pulp, and oxygen-sodium alkali pulp can be used.

The chemical pulp may be obtained by adding a cyclic ketone compound (for example, hydrazine, 1,4-dihydroxy-9,10-dione oxime, etc.) as a digestion aid to the above-mentioned distillate solution. Digested pulp. Further, as the chemical pulp, particularly suitable for use in the present invention is kraft pulp, which may be composed of a divided addition of a distillate and a co-current digestion and a steaming in a continuous distillation furnace. Correct the pulp obtained by the alkaline distillation method. These chemical pulps may be used singly or in combination with the state of the unbleached pulp, the state of the bleached pulp, or the state of the unpulped pulp, and the state of the pulping pulp.

Regarding the treatment of the cavitation phenomenon, in more detail, the flushing force generated by the bubble generated by the cavitation phenomenon is applied to the pulp fiber to promote the external fibrillation of the pulp (external fuzzing), and the internal reaction is suppressed. Fibrillation to adjust the degree of filtration. As the cavitation treatment, the cavitation jet treatment described in WO 2005/012632 can be employed.

In addition, the cavitation treatment can be combined with the mechanical beating treatment to externally fibrillate the pulp fibers. In the pulp suspension, it is possible to contain, in addition to the pulp fibers, old paper or a filler contained in the paper block or inorganic fine particles contained in the printing pigment. In addition to promoting the external fibrillation of the pulp fibers, the cavitation treatment can suppress the internal fibrillation. Therefore, if the apparatus using a fine machine such as a conventional machine uses mechanical strength to compare the pulp after the beating treatment, Under the same degree of filtration, a pulp which is more bulky and has excellent strength can be obtained. Therefore, the household tissue paper containing the pulp which is treated by the cavitation treatment of the external fibrils is softer and has excellent strength.

The Canadian standard water filtration degree of the prepared pulp by the cavitation treatment is preferably in the range of 50 to 650 ml in the case of chemical pulp, and in the case of mechanical pulp or old paper (deinked) pulp. A range of 50 to 400 ml is preferred. Further, in the case where the above two kinds of pulps are mixed, the total Canadian standard water filtration degree is preferably in the range of 100 to 550 ml.

Next, the cavitation treatment will be described in detail. The so-called "cavitation phenomenon" is such as the work of Mr. Kato (edited by Kato Yoji: the basis of the new version of cavitation and the recent entry; the bookstore, published in 1999), when the cavitation bubble bursts, for a few μm The local area will produce a punching force of up to a few GPa levels, and when viewed in a microscopic manner, when the bubble bursts, the temperature rises to several thousand °C due to the thermal compression. As a result, in the case where cavitation occurs, the temperature will rise together. Based on these phenomena, the cavitation phenomenon also brings about adverse factors such as damage, vibration, and performance degradation of the fluid machine. Therefore, in the past, the technical subject has been placed: it is necessary to control it to not cause cavitation. . In recent years, research on cavitation has progressed rapidly, and it has been developed to use the hydrodynamic parameters of the cavitation jet as an operational factor, to control the occurrence of cavitation with high precision, and even to control the flushing force. the size of. As a result, by controlling the rupture force of the bubble, it is expected that the powerful energy can be effectively utilized. Therefore, the cavitation phenomenon can be controlled with high precision by performing the operation and adjustment according to the parameters of the hydrodynamics. It has been shown to maintain the stability of the technical effect, and thus is no longer the cavitation phenomenon that occurs naturally in fluid machines with uncontrollable adverse effects, but the controlled gas. The bubble generated by the hole phenomenon is actively introduced into the pulp suspension, and the use of the energy efficiently is a feature of the present invention.

In the present invention, as a means for generating a cavitation phenomenon, a method using a liquid jet, a method using an ultrasonic oscillator, a method using an ultrasonic oscillator and a horn-shaped amplifier, and a laser irradiation can be exemplified. The method, etc., but is not limited to these methods. The liquid jet method is used because the cavitation bubble generation efficiency is high, and a cavitation bubble cloud having a stronger rupture force can be formed, which is more effective for the pulp fiber. The cavitation phenomenon which occurs according to the above method is significantly different from the cavitation phenomenon which naturally occurs in the conventional fluid machine and which has an uncontrollable adverse effect.

As described above, as the cavitation treatment, it is suitable to use the cavitation jet process using the liquid jet as described in WO2005/012632, which will be described in detail below.

The term "liquid jet" refers to a jet of a fluid in which a solid particle or a gas is dispersed or mixed in a liquid or a liquid, that is, a slurry of pulp or inorganic particles or a jet of liquid containing bubbles. The gas referred to herein may also contain bubbles generated by cavitation.

The cavitation phenomenon occurs when the liquid is accelerated and the local pressure becomes lower than the vapor pressure of the liquid, so the flow rate and pressure are particularly important. For this reason, the basic non-dimensional number, Cavity Number σ system used to express the cavitation state is defined as the following formula (please refer to the new version of the cavitation edited by Kato Yoji) The basis of the phenomenon and the recent advancement, published by the bookstore in 1999).

(p _∞ : general flow pressure (absolute pressure), U _∞ : general flow velocity, p _v : fluid vapor pressure (absolute pressure), ρ: density)

Here, the term "the number of cavitation phenomena is large" means that the place where the fluid flows is in a state where cavitation is less likely to occur. In particular, in the case where cavitation occurs via a nozzle or a restriction orifice in the cavitation jet, the pressure p ₁ (absolute pressure) from the upstream side of the nozzle, the pressure p ₂ (absolute pressure) on the downstream side of the nozzle, and the sample can be obtained. The saturated vapor pressure p _v (absolute pressure) of water rewrites the cavitation phenomenon σ into the following formula (2). In the cavitation jet, because the pressure difference between p ₁ , p ₂ , and p _v is large, The line p _{1 is} much larger than the state where p _{2 is} much larger than p _v , so the cavitation phenomenon σ can be further approximated by the following equation (refer to H. Soyama, J. Soc. Mat. Sci. Japan, 47 ( 4), 381 1998).

Therefore, the number of cavitation phenomena σ can be expressed by two values of the upstream side pressure and the downstream side pressure of the nozzle. Further, the pressures measured in the embodiments of the present invention are all measured by the instrument, and the number of cavitation phenomena σ in the present invention can be expressed by the following formula (3).

[Expression 3]

σ=p4/p3

(However, p3: pressure on the upstream side of the nozzle (instrument measurement pressure), p4: pressure on the downstream side of the nozzle (instrument measurement pressure))

The condition of the cavitation phenomenon in the present invention is preferably 0.001 or more and 0.5 or less, and more preferably 0.003 or more and 0.2 or less, and more preferably 0.01 or more and 0.1 or less. When the number of cavitation phenomena σ is less than 0.001, the pressure difference between the cavitation bubble and the surrounding is very low, so the effect becomes smaller, and the pressure difference of the water flow is lower than that of 0.5. Cavitation is hard to happen.

Further, when the ejection liquid is ejected through the nozzle or the restriction tube to cause cavitation, the pressure of the ejection liquid (pressure on the upstream side of the nozzle) is 0.01 MPa (measured by the instrument) and 60 MPa (instrument measurement) The pressure is preferably below, 0.7 MPa (measured by the instrument) or more than 30 MPa (measured by the instrument); 2 MPa (measured by the instrument) is preferably 15 MPa or more. If the pressure on the upstream side of the nozzle is less than 0.01 MPa (measured by the instrument), a pressure difference is unlikely to occur between the pressure on the downstream side of the nozzle and the effect is small. In addition, if the pressure on the upstream side of the nozzle is higher than 60 MPa (measured by the instrument), a special pump and pressure vessel must be used, and the energy consumed is increased, so that the cost is disadvantageous and the pulp is made. The fiber is excessively damaged and is not suitable for use as a papermaking material. In addition, the pressure in the container (pressure on the downstream side of the nozzle) is preferably hereinafter referred to as a static pressure of 0.05 MPa (measured by instrument) or 2.6 MPa (measured by instrument). The pressure is also applied to the downstream side by pressurizing the container for accommodating the sprayed liquid (pulp suspension), so that the pressure in the rupture zone of the cavitation bubble becomes high, and the pressure difference between the bubble and the surrounding becomes large. Therefore, the bubbles can be more violently broken, making the punching force larger. In addition, if the pressure inside the container becomes too high, the cavitation phenomenon itself becomes less likely to occur. Therefore, the pressure ratio ((instrument measurement pressure) / (instrument measurement pressure)) between the pressure in the container and the pressure of the ejection liquid is preferably in the range of 0.001 to 0.5.

Further, the speed of the jet flow of the ejection liquid is preferably in the range of 1 m/sec to 200 m/sec, and more preferably in the range of 20 m/sec to 100 m/sec. If the velocity of the jet is less than 1 m/sec, the pressure drop is small, and cavitation is difficult to occur, so the effect is weak. On the other hand, if the speed of the jet flow is larger than 200 m/sec, a high pressure is required, so that a special device must be used, which is disadvantageous in terms of cost.

The cavitation treatment in the present invention can be selected in any container such as a water tank or in a pipe, but is not limited thereto. In addition, although it is also possible to perform processing in a one-pass manner, it is possible to increase the effect by circulating it several times. In addition, a plurality of cavitation generation means can be used to perform processing in a side by side manner or in a tandem manner.

The jet used to cause cavitation, although it is also possible to produce a jet in the open-air container of the pulper, in order to control the cavitation, it is preferable to generate a jet in the pressure vessel. .

In the present invention, for example, a method of generating cavitation by a liquid jet is for a pulp suspension, for example, distilled water, tap water, industrial water, reuse water recovered in a papermaking process, water-squeezed pulp, and The running water, the pulp suspension, the alcohol, and the like are sprayed as the ejection liquid, but are not limited thereto. It is preferable to spray the pulp suspension itself as a spray liquid. In addition to the effect of the cavitation phenomenon occurring around the jet, the hydrodynamic shear of the high pressure jet from the restriction orifice can be obtained. Force, so it can play a greater role. Further, when a pulp suspension is used as the ejection liquid, all the amount of pulp to be treated may be circulated and processed.

When the cavitation phenomenon is generated by the liquid jet to perform the treatment, the solid content concentration of the pulp suspension to be treated is preferably 5% by weight or less, and 3% by weight or less, from the viewpoint of bubble generation efficiency. Preferably, the range of 0.1 to 1.5% by weight is optimal.

Further, the pH of the pulp suspension at the time of the treatment is preferably pH 1 to 13, pH 3 to 12 is more preferred, and pH 4 to 11 is particularly preferred. If the pH is less than 1, the corrosion of the device or the like will become a problem, and it is disadvantageous based on the viewpoints of materials and maintenance. On the other hand, if the pH exceeds 13, the pulp fiber will be yellowed, thereby lowering the whiteness, so it is not suitable. The method of maintaining the alkaline condition is excellent in the swelling property of the pulp fiber, and it is preferable because the amount of formation of the OH active radical can be increased.

The present invention increases the injection pressure of the liquid to increase the flow rate of the spray liquid, thereby producing a more powerful cavitation phenomenon. Further, by pressurizing the container for accommodating the liquid to be ejected, the pressure in the region where the cavitation bubble is broken becomes high, and since the pressure difference between the bubble and the surrounding becomes large, the bubble is violently broken and the squeezing force is also Become bigger. The term "jetting liquid" as used herein refers to a liquid that is ejected from a restriction orifice in a high pressure state, and "injected liquid" refers to a liquid that is ejected into a container or in a pipe. The cavitation phenomenon is affected by the amount of gas in the liquid. When the gas is too much, it will cause the bubbles and the bubbles to collide with each other and merge into one. Therefore, the rupture force will be absorbed by other bubbles, resulting in The cushioning effect causes the punching force to weaken. Therefore, since it is affected by the dissolved gas and the vapor pressure, the treatment temperature must be below the boiling point above the melting point. When the liquid is water as a medium, the treatment temperature is preferably in the range of 0 to 80 ° C, and more preferably in the range of 10 ° C to 60 ° C, and a high effect can be obtained. It is generally considered that the treatment temperature is selected at the intermediate point between the melting point and the boiling point, and the punching force tends to be the largest. Therefore, in the case of an aqueous solution, it is most suitable before and after 50 ° C, but even at a temperature below 50 ° C, Since it is not affected by the vapor pressure, a high effect can be obtained as long as it is within the above range. If the temperature is higher than 80 ° C, the pressure resistance of the pressure vessel used to generate cavitation will be significantly lowered, and the container is easily damaged, so it is not suitable.

In the present invention, by adding a substance such as a surfactant which lowers the surface tension of the liquid, the energy required to generate cavitation can be reduced. The substance to be added may be a known or novel surfactant, and examples thereof include a fatty acid salt, a higher alkyl sulfate, an alkyl benzoate, a higher alcohol, an alkyl phenol, a fatty acid or the like. A nonionic surfactant such as an oxyalkylene additive, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, or an organic solvent is not limited to these surfactants. It may also be composed of a single component of these surfactants or a mixture of two or more components. The amount of addition may be any amount required to reduce the surface tension of the ejection liquid and/or the liquid to be sprayed. In addition, as for the place to be added, it may be any one of the processes ahead of the place where cavitation occurs, but if the liquid is to be recycled, even if cavitation is generated It is no problem to add the place after the phenomenon.

In the present invention, the blending ratio (content) of the pulp after the cavitation treatment with respect to the whole pulp is not particularly limited, but the higher the blending ratio, the higher the strength and the softness of the household. Thin leaf paper. From this point of view, the blending ratio (content) of the pulp after the cavitation treatment is preferably 5% by weight or more, more preferably 30 to 100% by weight, and 60 to 100% by weight, based on the absolute dry weight of the whole pulp. Very good. If the blending ratio is less than 5% by weight, the softness and hand touch are not changed, and the strength cannot be increased.

Although the household leaf tissue is composed of a single layer or a plurality of layers, the single layer or the plurality of layers may be separately subjected to papermaking by cavitation treatment, or may be mixed with two or more cavitation processes for papermaking. In addition, papermaking can also be carried out after mixing the conventional soft muddy pulp, dry pulp, and deinked pulp (DIP) in the pulp after the cavitation treatment.

In the case where two sheets of household leaf paper composed of a plurality of layers are stacked and laminated, if the layer containing the cavitation-treated pulp is placed on the outside to be overlapped, since the layer touched by the hand is the content The cavitation process treats this layer of pulp, so it can further enhance the feel of the hand. Moreover, the lamination containing the cavitation-treated pulp is attached to the Yanji dryer for drying, and the face is disposed on the outer side of the two overlapping household thin-leaf papers, which further enhances the hand touch. sense.

Further, as a cavitation treatment pulp other than pulp, for example, chemical pulp (bleached kraft pulp (NBKP) or unbleached kraft pulp (NUKP), hardwood bleached kraft pulp (LBKP)) or unbleached kraft paper can be used. Pulp (LUKP), etc., mechanical pulp (grinded wood pulp (GP), mechanical finely ground pulp (RGP), thermomechanical treated pulp (TMP), chemical thermomechanical treated pulp (CTMP), etc.), deinked pulp (DIP) The pulp is mixed and used in any ratio.

Although the pulp which has been subjected to cavitation treatment is subjected to pulp which promotes external fibrillation, in some cases, pulp having scaly outer fibrils can be obtained, which will be described below.

According to the work of Mr. Isobe (Isobe Ming, "Material Chemistry of Cellulose"; University of Tokyo Press, p68, 2001), "Pulping of pulp" means mechanically imparting pulp fibers in a hydrated state. The brushing stress creates voids (internal fibrillation) between the microfibrils inside the pulp fibers, causing the fibrils on the outer side of the pulp fibers to fluff (external fibrillation), and the specific surface area thereof is increased to increase The pulp fiber has a swellability to water, and at the same time, microfibers are obtained by partially cutting the fibers and peeling off the outer peripheral surface of the fibers.

By the pulping treatment of the pulp, the bonding area between the fibers formed during papermaking will increase, and various mechanical properties, optical properties, and liquid absorbability will change. However, if the pulp fibers are observed on the basis of the molecular size, the molecular weight of the cellulose is only slightly lowered during the beating treatment, and the degree of crystallization is hardly changed. This is considered to be because the amorphous hemicellulose fraction is capable of absorbing mechanical energy like a cushioned cushion.

In addition, according to the work of Mr. Shijiji, etc. (the organization of wood by the island, etc.; Mori Press, p55, 1976), the external fibrils observed from the wood pulp after beating in a general method. It is a filamentous structure having a width of 0.4 to 1 μm observed by an optical microscope. The term "microfibril" refers to a structural unit of the element that exists in the cell wall and has a degree of 9 to 37 nm. A collection of wide-width cellulose molecules. In the pulp of the outer fibrils having a scaly form used in the present invention, the term "external fibrils having a characteristic scaly form" means a width of 3 μm or more, preferably with The surface of the pulp fiber is peeled or fluffed to the same extent as the width of the fiber, and the microfibrils are connected in the transverse direction to form an aggregate, which becomes a layer having a large width, that is, a microfibril on the surface of the fiber wall. The peeler is produced while maintaining the layer structure. Further, the range in which the thickness is from 2 nm to 2 μm is also characteristic. In addition, when observing the fiber by an electron microscope, it is preferable to carry out the measurement in a dry state in which hydrogen bonding is prevented, because if the fiber is simply dried, the external fibril is adsorbed due to capillary action. It is difficult to discriminate into the surface of the fiber, and it is difficult to observe the fibril very accurately.

The scaly outer fibrils in the present invention are characterized by being dyed with a high molecular weight dye having a molecular weight of 10,000 or more. That is, the outer fibril means a microfibril aggregate which can adsorb a high molecular weight dye having a molecular weight of 10,000 or more. As for the dye having a molecular weight of 10,000 or more, for example, the literature of Simon et al. (FL Simons, Tappi, 33(7), 312 (1950)), and the literature of Xiaochun et al. (Y. Xiaochun) Et al., CI of Direct Orange 15 (old Color Index (CI) no, 621, or CI Constitution no. 40002/3) as described in Tappi Journal, 78(6), 175 (1995). The citrus dyes such as Constitution No. 40000 to 40006 are not particularly limited as long as they are those which can dye fibers mainly composed of cellulose.

The dye having a molecular weight of 10,000 or more is described by the literature of Xiaochun et al., and it is known that the molecule having a hydrodynamic size of 5 nm or more cannot be infiltrated into the surface of the pulp fiber by light scattering measurement. 5nm pores. On the other hand, the fibrils composed of the aggregate of microfibrils on the surface of the pulp fibers are exposed on the outer side of the pulp fibers. Therefore, the dye molecules having a molecular weight of 10,000 or more are easily accessible, so that they can be adsorbed. The fibril portion can be selectively dyed.

In order to observe optically specifically for the fibril portion, Direct Blue 1 (old Color Index (CI) no. 518, or CI Constitution no. 24410) or Direct Blue 4 is used in the manner described in the aforementioned documents. Low-molecular dyes such as Direct Blue 15, Direct Blue 22, and Direct Blue 151 dye the entire fiber to enhance contrast and make it easier to observe. Although a low molecular dye is adsorbed on the entire fiber, the dye of the polymer is more strongly adsorbed, so that the low molecular dye can be replaced. As a result, the fibril portion of the adsorbable polymer dye (citrus dye) is dyed orange, and the pore portion of the fiber which cannot adsorb the polymer dye can be dyed by the low molecular dye (blue dye), so that it can be The fibril portion is especially highlighted. The low molecular dye contains a dye having a molecular weight of less than 10,000, preferably a molecular weight of less than 2,000, more preferably 51% or more of a molecular weight of 300 to 1,500.

In the pulp having the scaly outer fibrils of the present invention, when the fibers are measured in units of one, the area ratio of the outer fibril portion expressed by the following formula 4 is 20% or more, and the following formula 5 The peripheral length of the outer fibril portion shown is preferably 1.5 or more. When the scaly outer fibrils of the pulp of the present invention are compared with ordinary fibrils, the surface area is large, and therefore these values are also increased.

Area ratio (%) of the outer fibril portion = [(area of outer fibril portion) / (area of outer fibril portion + total surface area of pulp fiber)] × 100 (Expression 4)

The peripheral length of the outer fibril portion = (the circumference of the outer fibril portion + the total circumference of the pulp fiber) / (the total circumference of the pulp fiber) (Expression 5)

[effect]

The reason why the touch feeling and the strength of the facial tissue containing the pulp treated by the cavitation phenomenon are excellent is considered to be the following reason.

In general, in the case of high loft (low density) and a smooth surface, the hand touch of the tissue can be improved. However, as described above, the pulp treated by the cavitation phenomenon is a pulp which is particularly enhanced by external fibrillation. In other words, as described in WO2006/085598, since it is capable of retaining the rigidity of the fiber and promoting the external fibrillation, it is compared with the conventional mechanical treatment such as a two-disc grinder. If the pulp is formulated to have the same degree of bulkiness, the paper strength is improved. If the pulp is blended to the same strength, the bulkiness of the paper becomes higher.

Further, if the pulp treated by the cavitation phenomenon is used, the smooth surface of the metal roller or the like can be easily transferred to the paper surface, so that the paper is easily smoothed.

For these reasons, the facial tissue containing the pulp treated by cavitation is considered to have excellent hand touch and strength.

[Examples]

Hereinafter, the present invention will be specifically described by way of Examples and Comparative Examples, but the present invention is not limited to such Examples. Further, % shown in the examples and comparative examples means: % by weight unless otherwise specified. The pulp prepared in the following Examples and Comparative Examples was subjected to papermaking using a two-line three-layer Yankee paper machine. Wrinkles are caused by dry wrinkles by taking the difference in speed between the dryer and the reel. If it is not specifically stated, the two sides of the face paper (YD face) that is in contact with the Yankee dryer are facing outward (in contact with the user's hand), and the two are overlapped. After the two sheets facing each other are laminated together, they are exposed to the Yankee dryer, and then the dried surface is calendered by a soft calender. The pulp, whether in the case of the examples or the comparative examples, is produced by using a domestically produced broad-leaved tree chip in a kraft pulp process, and the bleached hector whiteness (brightness by Hunter) is 84% of broadleaf tree bleached pulp.

Further, the evaluation methods used in the examples and comparative examples are as follows.

<Hand touch>

Ten judges were commissioned to judge the touch of the hand and the feeling of the skin. It is expressed in the following different ways.

Very good: ◎, good: ○, ordinary: △, poor: ×

<Measurement of tensile strength (longitudinal)>

Tensile strength: The sample was cut into a width of 15 mm in the MD direction and the CD direction, and the tensile strength in each direction was measured in a single layer (1 ply), and the value calculated by the following formula was regarded as stretching. strength.

Tensile strength (g) = (MD tensile strength × CD tensile strength) ^1/2

<Measurement of Bulkness>

The paper thickness (mm) when the samples were overlapped by 10 layers was taken as the bulkiness.

<Measurement of unit area weight>

The measurement was carried out in accordance with Japanese Industrial Standard JIS P 8124:1998 (ISO 536:1995).

<Adjustment of Pulp Treatment Pulp>

The cavitation treatment is performed using the cavitation jet flow processing apparatus shown in Fig. 1. In the first drawing, a pulp suspension (concentration: 1.1%) (not shown) is accommodated in the sample tank 1, and the temperature sensor 12 and the agitator 13 are inserted into the sample tank 1. The pulp suspension of the sample tank 1 is introduced into the cavitation flow nozzle 3 as a spray liquid by a predetermined pipe through which the spool pump 4 is interposed. The nozzle 2 is provided in the lower portion of the cavitation jet container 3, and more specifically, the pulp suspension of the sample tank 1 is ejected from the nozzle 2 into the jet container 3. Further, a water supply valve 9 and a circulation valve 10 are provided in a pipe from the side of the sample tank 1 toward the jet flow container 3, and the pulp suspension in the sample tank 1 is supplied as the liquid to be sprayed into the jet flow container 3. On the other pipe from the side of the sample tank 1 toward the nozzle 2, an upstream side pressure control valve 5 is interposed. Further, on the other pipe from the upper portion of the jet flow container 3 toward the sample tank 1, a downstream side pressure control valve 6 is interposed, and by adjusting the respective pressure control valves 5, 6, the feed to the nozzle 2 can be adjusted. The spray pressure of the pulp suspension. Further, one upstream side pressure gauge 7 is provided on the input side of the nozzle 2, and one downstream side pressure gauge 8 is provided on the upper side of the jet flow container 3. Further, a drain valve 11 is provided in the lower portion of the jet container 3.

[Example 1]

The raw materials of the upper layer and the lower layer among the three layers are prepared in the following manner. The pulp sheet of the hardwood bleached kraft pulp is dissociated in a low-concentration pulping machine, and after adjusting to a desired concentration, the cavitation jet processing device (nozzle diameter: 1.5 mm) shown in Fig. 1 is used to spray the liquid. The pressure (pressure on the upstream side of the nozzle) is set at 8 MPa (measurement pressure of the instrument, flow rate of the jet flow is 80 m/sec), and the pressure in the injection container (pressure on the downstream side of the nozzle) is set at 0.4 MPa (measured by the instrument), and is performed once. (one pass) processing. Further, a pulp suspension having a concentration of 3% by weight was used as a spray liquid, and a pulp suspension (concentration: 3% by weight) in the container was subjected to cavitation treatment, and the Canadian standard water filtration degree was set to 435 ml. Raw material A. The tissue paper was produced from the raw material A and the intermediate raw material B (the pulp sheet of the hardwood bleached kraft pulp was dissociated in a low-concentration pulping machine, and the Canadian standard water filtration degree was set to 500 ml). The basis weight of the paper which was taken out of paper was adjusted to 16.6 g/m ² .

[Comparative Example 1]

For the raw materials of the upper layer and the lower layer, a double-disc grinder was used for the beating treatment instead of the cavitation treatment, and the Canadian standard water filtration degree was set to 470 ml to produce the raw material C. A facial tissue is produced from the raw material C and the intermediate raw material B. The basis weight of the paper which was taken out of paper was adjusted to 16.6 g/m ² .

As shown in Table 1, when the first embodiment was compared with the comparative example 1, the hand touch was the same, but the tensile strength of the first example was improved by about 20% as compared with the comparative example 1. The strength of Example 1 was also greatly improved compared to Comparative Example 1, and the bulkiness was slightly lowered.

[Embodiment 2]

The raw materials of the upper layer and the lower layer were treated in the same manner as in Example 1, and the standard water filtration degree of Canada was set to 420 ml to prepare a raw material D. To the raw material D and the intermediate raw material B, 0.1% of the wet paper strength enhancer (relative to the absolute dry pulp weight) was added to produce a facial tissue. The basis weight of the paper which was taken out of paper was adjusted to 13.0 g/m ² .

[Comparative Example 2]

The raw materials of the upper layer and the lower layer were treated in the same manner as in Comparative Example 1, and the Canadian standard water filtration degree was set to 410 ml to produce a raw material E. To the raw material E and the intermediate raw material B, 0.1% of the wet paper strength enhancer (relative to the absolute dry pulp weight) was added to produce a facial tissue. The basis weight of the paper which was taken out of paper was adjusted to 13.0 g/m ² .

As shown in Table 2, Example 2 showed better hand touch feeling than Comparative Example 2, and the tensile strength was almost the same. Further, Example 2 was improved by about 7% as compared with Comparative Example 2.

[Example 3]

For the raw materials of the upper layer and the lower layer, a cavitation jet type processing device (nozzle diameter: 1.5 mm) was used, and the pressure of the ejection liquid (pressure on the upstream side of the nozzle) was set to 8 MPa (measured by the instrument, and the flow rate of the jet was 80 m/sec). The pressure in the container to be sprayed (pressure on the downstream side of the nozzle) was set to 0.4 MPa (instrument measurement pressure), and two passes were performed, except that the same treatment as in Example 1 was carried out, and The Canadian standard water filtration is set to 390 ml to produce the raw material F. To the raw material F and the intermediate raw material B, 0.1% of the wet paper strength enhancer (relative to the absolute dry pulp weight) was added to produce a facial tissue. The basis weight of the paper which was taken out of paper was adjusted to 15.1 g/m ² .

[Comparative Example 3]

The raw materials of the upper layer and the lower layer were treated in the same manner as in Comparative Example 1, and the Canadian standard water filtration degree was set to 470 ml to produce the raw material G. A tissue paper was prepared by adding a wet paper strength enhancer of 0.1% (relative to the absolute dry pulp weight) to the raw material G and the intermediate raw material B. The basis weight of the paper which was taken out of paper was adjusted to 15.1 g/m ² .

As shown in Table 3, Example 3 showed better hand touch feeling than Comparative Example 3, and the tensile strength was about 20% higher. In Example 3, the tensile strength was greatly improved as compared with Comparative Example 3, but the bulkiness was slightly lowered.

[Example 4]

In addition, a broad-leaved bleached kraft pulp sheet having a high strength but a low hand touch tendency (a moisture content of the pulp sheet of about 50% by weight (relative to the absolute dry pulp weight)) is used as a raw material for the upper layer and the lower layer, in addition to The same treatment as in Example 1 was carried out, and the raw material H was produced by setting the Canadian standard water filtration degree to 440 ml. To the raw material H and the intermediate raw material B, 0.1% of the wet paper strength enhancer (relative to the absolute dry pulp weight) was added to produce a facial tissue. The basis weight of the paper which was taken out of paper was adjusted to 15.1 g/m ² .

[Comparative Example 4]

Using a broad-leaved bleached kraft pulp sheet (the moisture content of the pulp sheet is about 10% by weight (relative to the absolute dry pulp weight)), which is easy to feel by hand, is used as a raw material for the upper layer and the lower layer, and other things are compared and compared. In the same treatment as in Example 1, the raw material I was produced by setting the Canadian standard water filtration to 480 ml. To the raw material I and the intermediate raw material B, 0.1% of the wet paper strength enhancer (relative to the absolute dry pulp weight) was added to produce a facial tissue. The basis weight of the paper which was taken out of paper was adjusted to 15.1 g/m ² .

As shown in Table 4, Example 4 using a broad-leaved bleached kraft pulp having a tendency to feel bad to the hand, and Comparative Example 4 using a hardwood bleached kraft pulp sheet having a hand-feeling tendency to be easily improved, in comparison The touch is almost the same. Further, in Example 4, the tensile strength was improved by about 40% as compared with Comparative Example 4.

1. . . Test slot

2. . . nozzle

3. . . Cavitation phenomenon jet container

4. . . Valve pump

5. . . Upstream pressure control valve

6. . . Downstream pressure control valve

7. . . Upstream pressure gauge

8. . . Downstream side pressure gauge

9. . . Water supply valve

10. . . Circulation valve

11. . . Drain valve

12. . . Temperature sensor

13. . . Blender

Fig. 1 is a schematic view showing a cavitation flow type jet processing apparatus used in an embodiment of the present invention.

Claims (3)

A household thin leaf paper is a household thin leaf paper composed of two or more paper layers, characterized in that at least one of the paper layers contains a punching force generated when the air bubbles generated by the cavitation phenomenon are broken. a pulp obtained by pulp fibers (cavitation treated pulp), the paper containing cavitation treated pulp is laminated to a Yanji dryer for drying; and a paper layer containing cavitation treated pulp is disposed outside . The household thin leaf paper according to claim 1, wherein the cavitation treatment pulp has scaly outer fibrils. The household thin-leaf paper according to claim 1 or 2, wherein the content of the cavitation-treated pulp is 30 to 100% by weight based on the absolute dry weight of the whole pulp.