JP6666377B2 - Absorbent paper - Google Patents

Description

  Paper for kitchens, used for wiping dirt attached to foods, draining foods, wiping drip leaching from foods, wrapping and protecting foods when storing foods, etc. in stores and kitchens handling fresh foods The present invention relates to a liquid-absorbing paper which is also called a wiping paper.

  In shops, kitchens, food processing plants, etc. that handle fresh food, wipe off dirt attached to ingredients, drain food, wipe drip leaching from ingredients such as meat and fish, wrap and protect ingredients when storing ingredients, etc. There is a liquid absorbing paper which is also referred to as kitchen paper and the like used for the above.

  This absorbent paper is made of a pulp-only fiber material, a mixture of pulp and chemical fiber, or a chemical fiber only. The "paper" produced by the wet papermaking method is inexpensive and is most widely distributed on the market. This liquid absorbing paper is required to be inexpensive because it is mainly used for business purposes, and unlike other paper used for wiping or absorbing liquid such as moisture, it has high strength and fresh food. When wrapping and storing products, it is required that the freshness of the fresh food products be maintained.

Conventional general liquid-absorbing paper is mainly made of a single-ply embossed or non-embossed paper having a relatively high basis weight of about 40 to 50 g / m ^2, which is made by dry creping. By increasing the basis weight, the liquid absorptivity is enhanced, and furthermore, unevenness is formed by embossing to reduce the contact area with the food material, thereby maintaining the freshness of the fresh food product.

  However, in the conventional liquid-absorbing paper, the crepe elongates when absorbing the liquid, and the crepe elongation reduces the height difference of the unevenness due to the embossing process, increases the contact area with fresh food products, and decreases freshness retention. There was something. In particular, the embossed material is sometimes applied with pressure, so that the liquid absorbing speed may be low, and the liquid retaining property and the liquid absorbing amount may not be sufficient. Some household kitchen papers have high liquid absorption properties, but their strength is not sufficient, and it is difficult to use them as liquid absorption papers. In particular, it is easily broken when drip is absorbed or drained.

  On the other hand, there is known a method in which irregularities are imparted to the surface during papermaking by combining a wet crepe method and a bulky wire (for example, Patent Document 1). The liquid-absorbent paper according to Patent Document 1 has a structure in which unevenness on the surface is unlikely to be crushed even during liquid absorption, and it is easy to maintain a state in which the drip or the like absorbed from the food does not easily come into contact with the food even when absorbing the liquid. The nature has increased.

  However, it is desirable that the freshness retention property of the liquid absorbing paper is higher, and although further improvement of the freshness retaining property is required, even if the contact area between the liquid absorbing paper and the food material at the time of liquid absorption is reduced, the absorbed drip And the like, the number of fungi increases with time, so it is difficult to further improve the freshness retention by merely reducing the contact area.

  On the other hand, a thin paper having a cationic antibacterial agent and a deodorizing property by providing porosity is also known as in Patent Document 2 below. However, in a liquid absorbing paper mainly used for touching foodstuffs, cationic paper is used. It is not preferable to provide an antibacterial agent or a porous material that may be detached, and such an antibacterial agent or porous material increases the cost of the liquid absorbing paper.

Japanese Patent No. 5755464 Japanese Patent No. 6130869

  Therefore, a main object of the present invention is to provide a liquid-absorbing paper that has good releasability from food materials and is particularly excellent in keeping freshness.

  The means for solving the above problems are as follows.

The first means is
A one-ply liquid-absorbent paper obtained by wet-making the fiber raw material,
Constituent fiber contains 40% by mass or more of softwood pulp,
The basis weight is 35 to 55 g / m ² ,
The specific volume is 4.0 to 7.0 cm ³ / g,
Having a crepe formed by a wet crepe method,
And has a mesh mark of bulky wire of 10 to 26 lines / inch,
Containing an organic acid and having an acidity of pH 5.5 or less;
A liquid absorbing paper characterized by the above.

A second means is the liquid absorbing paper according to the first means, which contains the organic acid salt of the organic acid.
The liquid absorbing paper according to the first means.

The third means is
The dry tensile strength in the longitudinal direction is 2100-3800 cN,
The dry tensile strength in the transverse direction is 1500-3500 cN,
The longitudinal wet tensile strength is 1000-2000 cN,
The transverse wet tensile strength is 600 to 1300 cN,
The liquid absorbing paper according to the first or second aspect.

  The fourth means is the liquid absorbing paper according to the first to third aspects, wherein the organic acid is provided on one of the paper surfaces.

  ADVANTAGE OF THE INVENTION According to this invention, the releasability with foodstuffs is good and the liquid-absorbing paper excellent in especially freshness retention is provided.

FIG. 2 is an enlarged view of a wet crepe absorbent paper having a bulky wire mesh mark. FIG. 3 is an enlarged view of a dry crepe liquid-absorbing paper having unevenness due to embossing. It is a figure for explaining the manufacturing process of the liquid absorption paper concerning the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The absorbent paper according to the present invention is used for wiping dirt attached to food, draining the food, wiping drip leaching from the food, wrapping and protecting the food during storage, etc. It is also called kitchen paper or the like.

  In particular, the liquid-absorbing paper according to the present invention can be used to prevent the drying of foods, for example, when these foods are wrapped to temporarily store vegetables, fresh fish, sashimi blocks (saku), block meat, and the like. Absorption of drip (leaching liquid) from the surface is performed. At this time, if the state where the contact area with the food material is small is maintained, it functions so that the freshness of the food material is further maintained.

  The absorbent paper according to the present invention is a so-called “paper” made by a wet papermaking method, and does not include a nonwoven fabric. In the liquid absorbing paper according to the present invention, at least 98% by mass of the constituent fibers are made of pulp fibers, and particularly, 100% by mass are made of pulp fibers. When the pulp fiber content is 100% by mass, it is easy to make a paper by an ordinary wet papermaking method, and the effects of the present invention can be exhibited. However, if it is less than about 2% by mass as far as wet papermaking is possible, chemical fibers and the like can be contained.

The liquid absorbing paper according to the present invention has one ply and a basis weight of 35 to 55 g / m ² . By using one ply, the cost can be reduced, and the workability when wrapping the food is excellent without peeling off the ply. Further, by slightly increasing the basis weight to 35 to 55 g / m ² , it becomes easy to secure the liquid absorption amount and the absorption speed. The basis weight according to the present invention is a value measured based on JIS P 8124 (1998).

The absorbent paper according to the present invention characteristically contains an organic acid and has an acidity of pH 5.5 or less. The acidity according to the present invention is a value measured by wetting a paper surface with pure water ( ² cc / 10 cm ² ) and using a flat type pH meter MJ-120A manufactured by Sato Shoji Co., Ltd. and an equivalent machine having the same measurement principle. It is. Bacterial growth is suppressed by setting the acidity to pH 5.5 or less. That is, bacteria grow over time in the liquid-absorbent paper that has absorbed the drip, and these bacteria cause deterioration of freshness and decay of the food material. Even if the contact area between the food material and the absorbent paper is reduced, the proliferation of bacteria cannot be suppressed. Here, it is said that the temperature, moisture, nutrient, and pH must be in a specific environment in order for general bacteria to grow, and the growth of many bacteria is suppressed at pH 5.5 or lower. . Therefore, in the absorbent paper according to the present invention, the acidity of the paper is adjusted to pH 5.5 or less to suppress the growth of bacteria. The lower limit of the acidity is about pH 3.0, and the preferable range of the acidity is pH 4.0 to pH 5.0. If the pH is less than 3.0, the acidity is too strong, and the ingredients may be damaged by decomposition of components such as proteins.

  In the liquid absorbing paper according to the present invention, the paper is made acidic by including an organic acid. As a technique for acidifying paper, there has been conventionally known a method of using a sulfuric acid band as an internal additive during papermaking to make acidic paper. However, the sulfuric acid band deteriorates the strength of the paper and has a problem in terms of food safety when used for absorbent paper that comes into contact with foodstuffs. Many organic acids have higher safety when used in foodstuffs compared to organic antibacterial agents represented by phenolic and piguanide types. As a liquid absorbing paper, sufficient strength and safety can be secured. As organic acids, those derived from food additives and natural products are desirable, and those that are toxic to the human body, have an excessive odor, or change the taste of foods are not desirable. Even if it has an odor or exhibits a sour taste, it may be any as long as it does not change the smell or taste of the foodstuff in such an amount that it can be adjusted to pH 5.5 or less. Specific examples include citric acid, malic acid, lactic acid, tartaric acid and the like. In order to include the organic acid, a chemical solution containing the organic acid may be applied to the base paper as described later.

  Further, the liquid absorbing paper according to the present invention preferably contains an organic acid and an organic acid salt of the organic acid. For example, when citric acid is included as the organic acid, it is desirable to include a citrate such as sodium citrate as the organic acid salt. Examples of the organic acid salt include potassium salt, sodium salt, calcium salt and the like. When an organic acid salt is contained, the food becomes less painful and freshness retention is enhanced. A buffer that suppresses a sudden pH change that is excellent in pH stability because the liquid contained in the absorbent paper contains an organic acid and an organic acid salt due to the wetting when absorbing the drip or drip. Is formed. In order to include the organic acid salt together with the organic acid, a chemical solution containing the organic acid and the organic acid salt may be applied to the base paper. Furthermore, when an organic acid salt is included together with the organic acid, a chemical solution containing the organic acid and the organic acid salt, that is, a buffer solution can be applied to the base paper, which is also advantageous in terms of corrosiveness of the papermaking equipment. In other words, the corrosion rate of iron, nickel, and castings used in paper machines decreases when the pH is less than 4, so that if they contain an organic acid salt, they can be applied as a buffer solution during production, thereby protecting the production equipment. From the viewpoint, it is preferable to include an organic acid salt. Here, the ratio between the organic acid and the organic acid salt is preferably from 1: 1 to 1: 0.5, and more preferably from 1: 1 to 1: 0.75.

  The organic acid and the organic acid salt may be impregnated into the entire liquid absorbing paper, but may be applied to only one surface of the paper and may be unevenly distributed on one surface of the paper, or may be attached to one surface of the paper. May be present. An organic acid and an organic acid salt only need to be provided on the paper surface while being in contact with the food material. In this case, there is an advantage in terms of manufacturing cost and chemical solution cost.

  In the absorbent paper according to the present invention, softwood pulp accounts for 40% by mass or more of the fiber raw material. Softwood pulp includes softwood kraft pulp (NBKP), softwood unbleached pulp (NUKP), and the like. Softwood pulp has a long fiber length and tends to develop stiffness, and easily diffuses and absorbs water quickly along the fiber. In the liquid absorbing paper according to the present invention, it is most preferable that 100% by mass of the fiber raw material is pulp fiber and 40% by mass or more of the pulp fiber is made of softwood pulp. When the proportion of the softwood pulp is 40% by mass or more, the drip absorption from the food material is excellent, and a moderate stiffness that does not drip even if the drip is absorbed can be developed. In addition, since the liquid-absorbing paper according to the present invention is used for the purpose of touching foods, it is preferable that the liquid-absorbing paper does not include waste paper pulp. Further, the proportion of softwood pulp in the fiber raw material is preferably 60% by mass or more. In particular, in the case of using unbleached pulp (NUKP) of softwood, the content is preferably 80% by mass or more, and more preferably 95% by mass or more. As the pulp fiber other than the softwood pulp in the absorbent paper according to the present invention, hardwood pulp is desirable. As the hardwood pulp, hardwood kraft pulp (LBKP) and hardwood unbleached pulp (LUKP) can be used. In particular, when unbleached softwood pulp (NUKP) is used, it is preferable to use unbleached hardwood pulp (LUKP). When softwood kraft pulp (NBKP) is used, hardwood kraft pulp (LBKP) is preferably used. desirable. When pulp fibers are composed of softwood kraft pulp (NBKP) and hardwood kraft pulp (LBKP), the ratio of softwood kraft pulp (NBKP): hardwood kraft pulp (LBKP) should be 40:60 to 60:40. Is desirable.

On the other hand, the liquid absorbing paper according to the present invention has a specific volume of 4.0 to 7.0 cm ³ / g. The larger the value of the specific volume, the larger the gap between the fibers. When the specific volume is in this range, the mixture is moderately dense and stiff. The specific volume is a value [cm ³ / g] obtained by dividing the paper thickness [μm] by the basis weight [g / m ² ]. In addition, the paper thickness may be appropriately adjusted in a range where the specific volume can be achieved in relation to the basis weight. The paper thickness here is a value measured using a dial thickness gauge (thickness measuring device) “PEACOCK G type” (Ozaki Seisakusho) under the conditions of JIS P 8118 (1998). Specifically, check that there is no dust and dust between the plunger and the measuring table, lower the plunger on the measuring table, move the memory of the dial thickness gauge to zero, and then Raise the plunger, place the sample on the test bench, slowly lower the plunger perpendicular to the paper and read the gauge at that time. At this time, just put the plunger. The terminal of the plunger is made of metal and a plane having a diameter of 10 mm is perpendicular to the plane of the paper. The load at the time of measuring the paper thickness is about 70 gf. Note that the paper thickness is an average value obtained by performing the measurement 10 times.

  On the other hand, the liquid absorbing paper according to the present invention has a crepe formed by a wet crepe method. Crepe by the wet crepe method (hereinafter, also simply referred to as wet crepe) is a crepe formed in a wet paper state, and has a property that the crepe is hardly stretched even when a liquid is absorbed. Since the liquid absorbing paper according to the present invention has wet crepe, even when absorbing the drip of foodstuff, the crepe is hardly stretched and the unevenness due to the fine crepe is easily maintained on the surface. For this reason, when wrapping and storing the food material, the crepe is hard to stretch even when the drip leaches from the food material and absorbs it, and the unevenness is easily maintained, so the contact area with the food material is hard to increase, and the freshness retention is enhanced. .

  Further, the absorbent paper of the present invention has a bulky wire mesh mark of 10 to 26 lines / inch. More preferably, it has a bulky wire mesh mark of 15 to 21 lines / inch. A bulky wire is one mode of a papermaking net used for transferring wet paper in wet papermaking, and in particular, a bulky wire of 10 to 26 lines / inch is relatively sparse. The present inventors, in addition to wet crepe, by forming a mesh mark with a bulky wire on the paper, when wrapping the food and storing, when the drip leached from the food and absorbed it, the paper surface Irregularities are maintained and the contact area with the food material is not expanded, and the above range of the irregularities is a preferable range of the contact range between the contained organic acid and the food material, and the maintenance of the unevenness and the organic acid and the like. A high freshness maintaining function is exhibited in combination with the action. Here, the characteristic mark of the bulky wire mesh in the liquid-absorbing paper of the present invention is not only a trace of each wire formed on the surface as shown in an enlarged view of the paper surface in FIG. A portion that looks like a very sparse fiber is regularly formed at a position corresponding to the hole existing therebetween (in the figure, a part of the approximate wire position of the bulky wire is shown as BW). This mesh mark can be formed by a manufacturing method described later. Then, the mesh mark is maintained even in a wet state as shown in an enlarged view of the paper surface at the time of water absorption in FIG. In other words, the liquid-absorbent paper of the present invention makes it difficult for the wet crepe and mesh marks to bend the paper surface and easily maintain the unevenness of the paper surface. A suitable contact property is maintained without sticking to the sheet, and an effect of suppressing the growth of bacteria by the organic acid is exhibited, so that a high freshness maintaining function is secured. In addition, the embossing and mesh marks enhance the releasability from the food material.

  For comparison, FIG. 2 shows an enlarged view of the surface of a conventional liquid-absorbing paper in which only the irregularities formed by embossing are formed on a conventional dry crepe paper. FIG. 2A shows the time of drying, and FIG. 2B shows the time of absorbing water. Comparing FIGS. 2A and 2B, the unevenness due to the embossing is lost by water absorption, and especially when water is absorbed, it becomes flat and easily sticks to food materials and the like.

  The liquid-absorbent paper according to the present invention may have irregularities formed by embossing, but the liquid-absorbent paper according to the present invention may have a relatively high basis weight and a dense specific volume in one ply. Desirably, since it is required to be inexpensive, it is desirable that there is no unevenness due to embossing.

  Moreover, it is desirable that the liquid-absorbent paper according to the present invention has a wet tensile strength in the vertical direction of 1000 to 2000 cN and a wet tensile strength in the horizontal direction of 600 to 1300 cN. The wet tensile strength according to the present invention refers to a value measured based on JIS P 8135 (1998). The test piece was cut into a strip having a length in the longitudinal direction of 150 mm and a length in the transverse direction of 25 mm. The wet tensile strength of the liquid absorbing paper according to the present invention is extremely high, and has an extremely high strength even when drip is absorbed. Since the liquid-absorbing paper according to the present invention is often handled with wet hands, high wet strength is excellent in workability. The wet tensile strength can be sufficiently adjusted by a wet paper strength agent or the like within the range of the grammage according to the present invention.

  On the other hand, the absorbent paper according to the present invention has a dry tensile strength in the longitudinal direction of 2100 to 2600 cN and a dry tensile strength in the transverse direction of 1500 to 2300 cN. The dry tensile strength according to the present invention refers to a value measured based on JIS P 8113 (2008). Liquid-absorbing paper is often used for business purposes, does not have a perforated portion, and is generally used by drawing out an appropriate length from a rolled state and then tearing it. is there. With the above-mentioned dry tensile strength, it is intended to be easily broken at the time of use, and has a sufficiently high strength not to be broken in a normal use mode. The dry tensile strength can be adjusted by a dry paper strength agent or the like.

Here, the liquid absorbing paper according to the present invention preferably has a water absorption of 150 to 300 g / m ² . With the liquid absorbing paper of the structure according to the present invention, it can be sufficiently within this range. With this water absorption, mesh marks and unevenness due to embossing due to wet crepe are unlikely to disappear, and the freshness retention is extremely high. It will be excellent. This water absorption is a value measured by the following procedure. The amount of water absorption is determined by cutting a test piece to a length of 100 mm x a width of 100 mm (vertical and lateral errors ± 1 mm each), preparing a test piece and measuring the weight. Distilled water is put into a pan so as to have a depth of 20 mm, the cut test piece is immersed in distilled water up to the surface of the paper, and then pulled out of the distilled water and weighed after 30 seconds. Five measurements are performed for one test piece, and the average value is used as the measured value. Water absorption = [(weight after water absorption) − (weight before water absorption)] × 100 (unit: g / m ² )

  Next, an example of a method for producing a liquid absorbing paper according to the present invention will be described with reference to FIG. FIG. 3 is a schematic diagram of the papermaking facility X1. This manufacturing method includes a wet paper web forming step P1 of discharging papermaking raw materials onto the papermaking net 10 to form a wet paper web W1, a dewatering step P2 of performing dewatering of the wet paper web in the process of transporting the wet paper web W1, A wet crepe applying step P3 in which the wet paper W2 having passed through the dewatering step P2 is transferred to the roll 20, the wet paper W3 on the roll 20 is peeled off by the blade 40 and wet crepe is applied, and the wet crepe is transferred onto the bulky wire 50; A step P4 of pressing the wet paper web W4 on the wire 50 against the Yankee dryer 60 to form mesh marks and transferring the wet paper web W4 onto the Yankee dryer 60, and a step of drying the transferred wet paper W4 with the Yankee dryer. I have. Hereinafter, each step and the like will be described in detail.

  The papermaking raw material according to the present invention is a pulp slurry using the constituent fibers of the liquid-absorbing paper of the present invention as a fiber raw material, and this pulp slurry can be adjusted by adding an appropriate agent or the like by a known method. . The pulp slurry of the absorbent paper according to the present invention preferably has a freeness of 500 to 650 cc (CSF: Canadian Standard Freeness).

  Further, a wet paper strength agent is added to the pulp slurry in order to obtain a suitable wet tensile strength of the liquid absorbing paper according to the present invention. The addition amount depends on the papermaking equipment and the constituent fiber ratio, but is preferably 15 to 35 kg / pulp t. It is also desirable to add 10 to 30 kg / pulp t of the dry paper strength agent. Use of these paper strength agents facilitates adjustment to a desired paper strength. The paper strength agent can be appropriately selected from known ones.

  In order to manufacture the liquid-absorbent paper according to the present invention, a wet paper web W1 is formed by discharging the above-mentioned papermaking raw material in an amount corresponding to the grammage of the commercial wiping according to the present invention from the inlet 1 onto the papermaking net 10. Then, the wet paper web W1 is dewatered (dewatering step) on the papermaking net 10. In the production method according to the present invention, when dewatering on the papermaking net 10, press dewatering may be performed using a press roll or the like. This makes it easier to form mesh marks.

  Next, the wet paper web W1 is picked up from the papermaking net to the roll 20, and transferred to the bulky wire 50 while being peeled off from the roll 20 by the blade 40. Here, in the liquid-absorbing paper according to the present invention, in order to ensure the formation of a mesh mark of the bulky wire, the dewatering in the papermaking net 10 is slightly increased, and the wet paper is appropriately bulked with water. It is desirable to transfer to. Here, the preferable crepe rate at the time of applying wet crepe in the present invention is 5 to 25%. If the crepe ratio is less than 5%, it is difficult for the bulk to appear, the effect of improving water absorption and oil absorption is small, and the paper is hard and work becomes difficult. If it exceeds 25%, the tensile strength in a wet state decreases and the strength at the time of peeling is poor. In the present embodiment, the crepe rate can be calculated as follows. Creep rate: {(peripheral speed of Yankee dryer in FIG. 3) − (peripheral speed of roll in FIG. 3)} / (peripheral speed of Yankee dryer) × 100.

  When the wet paper web W3 is transferred onto the bulky wire 50, traces of each wire are formed on the contact surface of the wet paper web W3 in the process of transferring the bulky wire 50. Although it is not clear, it is presumed that a portion where the fibers are sparse is also formed by dehydration from the gap between the wires.

  Next, the wet paper web W4 is transferred from the bulky wire 50 onto the Yankee dryer 60. At this time, the transfer is performed by pressing the bulky wire 50 against the Yankee dryer 60. The regular irregularities on the surface of the bulky wire 50 are transferred to the surface of the wet paper web W4, and the holes where the fibers are sparse are formed and fixed. It is desirable that the transfer is performed by pressing the bulky wire 50 against the Yankee dryer 60 with one touch roll 55. By using one touch roll 55, the internal structure and the surface structure of the liquid absorbing sheet of the bulky wire 50 can be suitably modified, and a reduction in bulk can be prevented.

  Here, the bulky wire 50 used in the present invention has a mesh size of 10 to 50 (lines / inch). The thickness of the wire constituting the bulky wire 50 is about 0.5 mmφ. In addition, it is desirable that the unevenness difference (difference between the top and the bottom) of the wet paper provided by the bulky wire 50 be 0.4 to 1.0 mm. This is adjusted by the surface configuration of the bulky wire 50, the contact pressure with the Yankee dryer 60, the thickness of the wet paper W4, the moisture content, and the like.

  Thus, mesh marks are formed by transferring the wet paper W4 to the Yankee dryer 60 via the bulky wire 50.

  The wet paper web W4 transferred to the Yankee dryer 60 is dried in a process in which the wet paper W4 adheres to the surface of the Yankee dryer and is conveyed. Thereafter, the wet paper W4 is peeled off from the Yankee dryer 60 by a blade 61, and is appropriately wound up to obtain the suction paper according to the present invention. The base paper T is a liquid paper. The sheet W5 is peeled off from the Yankee dryer 60 by the blade 61. The blade 61 is merely a trigger for peeling off the sheet W5 from the Yankee dryer 60, and at this time, is so-called dry crepe not given? This is given only to the extent that it does not affect the elongation of the liquid absorbing sheet that is almost manufactured. This is because the surface of the sheet W5 already has irregularities due to the mesh marks of the wet crepe and the bulky wire in the former stage, and the adhesive force to the Yankee dryer is reduced. Of course, it is also possible to intentionally adjust the speed of the Yankee dryer and the winding means in the subsequent stage so that excessive dry crepe is not applied.

Here, the chemical solution containing the organic acid may be applied by unwinding the base paper T from the roll of the base paper T wound up by the paper making equipment X1 and applying the solution by a roll transfer method such as a printing apparatus. It is preferable to apply to the wet paper webs W1 to W5 by a spraying method such as spray application or the like, and particularly to apply the wet paper webs W1 to W3. In the example shown in FIG. 3, the chemical liquid L is applied to the wet paper web W1 by the spray coating device 15 from one side. When the wet papers W1 to W3 are applied in a non-contact manner as described above, it can be manufactured without affecting the paper surface. The application of the chemical solution is performed only from one side of the wet paper webs W1 to W3 in the papermaking facility. However, if it is applied to the base paper T, it may be performed from both sides. As described above, if the chemical solution is applied only to one surface in contact with the food material, it can be manufactured at a low cost. On the other hand, as for the chemical solution containing an organic acid, it is desirable that the solution be a buffer solution containing an organic acid salt as described above. If the wet paper W1 to W3 is spray-coated as a buffer, the papermaking equipment is hardly corroded. In particular, if this is the case, it is preferable that the acidity of the drug solution be pH 4.0 or higher. In addition, what is necessary is just to adjust the ratio of the organic acid: organic acid salt in a chemical solution to 1: 1 to 1: 0.5. The application amount of the chemical is desirably 0.5 to 2.0 g / m ^{2 on} one side. More specifically, it can be appropriately adjusted in consideration of the application device, the viscosity of the chemical solution, the basis weight of the base paper T, the set pH value, and the like.

  The liquid absorbing paper made of the base paper T containing the organic acid thus formed is thereafter provided in a commercially available form by appropriately converting it into a rolled product by a known method.

  An example according to the present invention and a comparative example thereof were prepared, and each physical property value was measured. In addition, a test was performed on the reproduction of bacteria and retention of freshness.

  The papermaking conditions for each example are shown in Table 1, and the qualities for each example are shown in Tables 2 and 3. Table 2 shows the values immediately after the production, and Table 3 shows the values after performing an accelerated deterioration test of exposure to an environment of a temperature of 80 ° C. and a humidity of 65% for 24 hours. Table 4 shows the bacterial reproduction and freshness retention.

  As for the measurement methods such as the wet tensile strength which have already been described, the measurement was performed according to the measurement method. Further, the softness in the table was measured according to a handle ometer method according to JIS L 1096 E method. However, the test piece was 100 mm × 100 mm in size, and the clearance was 5 mm. The measurement was performed 5 times each in the vertical direction and the horizontal direction, and the average value of all 10 measurements was expressed in units of cN / 100 mm. Softness is one of the indicators of softness. The elongation was measured according to a sample related to dry tensile strength and a measurement procedure using a load cell tensile tester TG-200N manufactured by Minebea Co., Ltd. in accordance with the tensile test of JIS P 8113 (1998).

Bacterial growth in Table 4 was performed as follows based on JIS L 1902. 0.2 mL of a bacterial solution adjusted to about 1.0 × 10 ⁵ cuf / mL was cut into 10 cm × 10 cm square samples. Immediately after the inoculation and after culturing at 37 ± 2 ° C. for 18 hours, the cells were washed out with 20 mL of SCDLP, and the fungi were measured by a pour culture method using a standard agar medium. Agar culture was performed at 37 ± 2 ° C. for 40 to 48 hours.

The bacterial growth in Table 5 was carried out as follows according to JIS L 1902 by changing the conditions. 0.4 mL of a bacterial solution adjusted to about 1.0 × 10 ⁶ cuf / mL was cut into 5 cm × 5 cm square samples. Immediately after the inoculation and after culturing at 35 ± 1 ° C. for 24 hours, the cells were washed out with 10 mL of SCDLP, and the fungi were measured by a pour culture method using a standard agar medium. The agar culture was performed at 35 ± 1 ° C. for 40 to 48 hours.

  In the freshness retention test, the ingredients (beef thigh meat, chicken fillet, sashimi yellowfin tuna) were wrapped with the samples according to the respective examples, further wrapped with a food wrap film (Saran wrap manufactured by Asahi Kasei Chemicals Co., Ltd.), and refrigerator (5 to 10 ° C.) ), And the freshness of each food was checked. In the evaluation in the table, 5: no deterioration in freshness is observed, 4: slight deterioration in freshness is observed, 3: fading and deterioration in freshness are observed, 2: partially discolored and unsuitable for eating. 1: Discoloration and offensive odor.

  Comparing Tables 2 and 3, first, the examples according to the present invention are sufficiently maintained in strength and the like even in the accelerated deterioration test, and are sufficient as products.

  Further, looking at Table 4, in Example 1 and Example 2 of the present invention, the growth of bacteria was suppressed and freshness retention was lower than that of Comparative Example 1 containing no organic acid and having a pH of 6.8. You can see that it is increasing. In particular, in Example 1 having a pH of 4.8 and Example 2 having a pH of 4.6, it was confirmed that the number of bacteria was reduced, and a higher result was obtained regarding the freshness retention. In addition, looking at Table 5, the test was carried out by changing the number of bacteria and the like. In Example 3 at pH 5.5 and Example 2 at pH 5.2, the growth of fungi was suppressed. Compared with the freshness retention in the sensory evaluation, the results are superior to Comparative Examples 1 and 2. From these results, it can be said that the liquid absorbing paper according to the present invention has excellent freshness retention.

  X1: paper making equipment, 1: inlet, 10: paper making net, 15: chemical applying device (spray coating device), L: chemical containing organic acid, W1 to W5: wet paper, T: base paper, P1: wet paper forming process , P2: dehydration step, P3: wet crepe applying step, P4: transition step from bulky wire to Yankee dryer, 20: roll, 40: blade, 50: bulky wire, 55: touch roll, 60: Yankee dryer, 61 ... Blade, BW ... bulky wire position.

Claims (4)

A one-ply liquid-absorbent paper obtained by wet-making the fiber raw material,
Constituent fiber contains 40% by mass or more of softwood pulp,
The basis weight is 35 to 55 g / m ² ,
The specific volume is 4.0 to 7.0 cm ³ / g,
Having a crepe formed by a wet crepe method,
And has a mesh mark of bulky wire of 10 to 26 lines / inch,
Containing an organic acid and having an acidity of pH 5.5 or less;
Liquid absorbing paper characterized by the above.   2. The liquid absorbing paper according to claim 1, comprising an organic acid salt of the organic acid. The dry tensile strength in the longitudinal direction is 2100-3800 cN,
The dry tensile strength in the transverse direction is 1500-3500 cN,
The longitudinal wet tensile strength is 1000-2000 cN,
The transverse wet tensile strength is 600 to 1300 cN,
The liquid absorbing paper according to claim 1.   The liquid absorbing paper according to any one of claims 1 to 3, wherein the organic acid is provided on one surface of the paper.

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