JP2015209615A - Fluffed pulp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing fluffed pulp which is low-energy and is excellent in water absorption without execution of a chemical treatment.SOLUTION: Fluffed pulp is obtained by fibrillating pulp containing sulfite pulp by a mechanical treatment. Since the pulp is excellent in fibrillating properties, fluffed pulp can be produced with low energy. The fluffed pulp is excellent in water absorption and preferably used in absorbers, including paper diapers, urine absorbing pads and light incontinence pads.

Description

  The present invention relates to fluffed pulp produced from sulfite pulp as a raw material.

  Fluffed pulp is produced by defibrating wood pulp by mechanical treatment, and is used as an absorbent member for absorbent articles such as disposable diapers and air-laid nonwoven fabric materials. .

  As a method for producing fluffed pulp, a method using mercerized cellulose as a raw material in order to improve liquid absorbency and release (Patent Document 1), a method using ozone-treated cellulose fiber as a raw material (Patent Document 2) ), A method using a crosslinked cellulose fiber as a raw material (Patent Document 3), and a method of adding a hydrophobizing chemical to fluffing (Patent Document 4).

JP-A-8-13370 JP-A-8-667 JP-A-8-269869 JP-A-8-10284

  However, a large amount of energy such as electric power is required to produce fluffed pulp by completely defibrating wood pulp by mechanical treatment even in the above method. Moreover, when using fluffed pulp for the absorber used for a paper diaper etc., the improvement of the further water absorption is calculated | required.

  Then, the subject of this invention is providing the method which can manufacture a high quality fluffed pulp with low energy.

  As a result of intensive studies by the inventor in order to solve the above-mentioned problems, fluffed pulp having a low density and low density as well as having good water absorption can be obtained by fibrillating pulp containing sulfite pulp by mechanical treatment. The inventors have found that the present invention can be obtained and have completed the present invention.

  Since the sulfite pulp of the present invention has low internal bond strength and excellent defibration in the state of a pulp sheet, fluffed pulp can be produced with low energy. Moreover, since the obtained fluffed pulp is excellent also in water absorption, it can be used suitably for the absorber used for a paper diaper etc.

  The fluffed pulp of the present invention is characterized by using sulfite pulp as a raw material pulp. By using sulfite pulp, it becomes possible to improve defibration and water absorption.

  Sulphite pulp is a pulp produced by a sulfite cooking (SP) method, and has a feature that the cellulose content is higher than that of kraft pulp. The alpha cellulose content is usually 90% or more for sulfite pulp, whereas it is usually less than 90% for kraft pulp.

  The sulfite cooking method is a method of cooking wood and / or non-wood (for example, chips) with a mixture of sulfite and sulfite. The sulfite cooking method includes an acidic sulfite cooking method, a bisulfite cooking method, a neutral sulfite cooking method, etc. depending on the pH of the cooking solution, but the sulfite pulp of the present invention sufficiently removes lignin and hemicellulose. Therefore, what was manufactured by the method of either an acidic sulfite cooking method or a bisulfite cooking method is preferable.

  The acidic sulfite cooking method uses sulfite and sulfite (calcium salt, sodium salt, magnesium salt, ammonium salt) as a cooking solution, and cooking is performed at a pH of 1.5 to 2.5 and a temperature of 130 to 160 ° C. In the bisulfite cooking method, sulfite (sodium salt, magnesium salt, ammonium salt) is used as a cooking solution, and cooking is performed at pH 2.5 to 5.5 and temperature 130 to 160 ° C.

  The raw material of the sulfite pulp of the present invention is wood chips. In the present invention, it is preferable to include wood chips made of softwood, and the size and tree species are not particularly limited, and may be a single kind of wood chip or a chip in which two or more kinds of wood are mixed. In the present invention, a high-quality dissolving pulp can be efficiently produced even if it is a softwood species that is relatively difficult to digest or bleach. As a softwood chip used in the present invention, for example, a larch genus or a pine genus wood chip can be suitably used. For example, Larix (hereinafter abbreviated as L.) leptolepis (larch), L. laricina (Tamarac), L. occidentalis (Larix larch), L. decidua (European larch), L. gmelinii (Guimatsu) Etc. For Pinus radiata, Pinus radiata, etc. For Pinus radiata, for Pseudotuga (P.) menziesii (Dacrasfer), P. japonica, Cryptomeria japonica, etc. And so on. Of these, radiata pine is preferred.

  In the present invention, hardwood wood chips can be used as a raw material. As the wood chips of hardwood, for example, maple, birch, beech, acacia, eucalyptus and the like can be suitably used. For the Eucalyptus genus, Eucalyptus (hereinafter abbreviated as E.) calophylla, E. citriodora, E .; diversiccolor, E.I. globulus, E.I. grandis, E .; gummifera, E .; marginata, E.M. nesophila, E.I. nitens, E.I. amygdalina, E .; camaldulensis, E .; delegenasis, E.I. gigantea, E .; muelleriana, E.M. obliqua, E .; regnans, E .; Sieberiana, E.I. viminalis, E .; camaldulensis, E .; marginata and the like.

  In the present invention, the unbleached (unbleached) pulp obtained after cooking can be subjected to various treatments as necessary. For example, bleaching can be performed on unbleached pulp obtained after sulfite cooking.

  In one embodiment, the pulp obtained by sulfite cooking can be subjected to oxygen delignification treatment. As the oxygen delignification used in the present invention, a known medium concentration method or high concentration method can be applied as it is. In the case of the medium concentration method, the pulp concentration is preferably 8 to 15% by mass, and in the case of the high concentration method, it is preferably performed at 20 to 35% by mass. As the alkali in oxygen delignification, sodium hydroxide and potassium hydroxide can be used. As oxygen gas, oxygen from a cryogenic separation method, oxygen from PSA (Pressure Swing Adsorption), VSA (Vacuum Swing Adsorption) Oxygen etc. from) can be used.

The reaction conditions for the oxygen delignification treatment are not particularly limited, but the oxygen pressure is 3 to 9 kg / cm ² , more preferably 4 to 7 kg / cm ² , the alkali addition rate is 0.5 to 4% by mass, and the temperature is 80%. ~ 140 ° C, treatment time is 20 to 180 minutes, and other conditions can be applied. In the present invention, the oxygen delignification treatment may be performed a plurality of times.

  The pulp that has been subjected to the oxygen delignification treatment is then sent to a washing step, and after washing, it is sent to a multistage bleaching step to perform a multistage bleaching treatment. The multi-stage bleaching treatment of the present invention is not particularly limited, but acid (A), chlorine dioxide (D), alkali (E), oxygen (O), hydrogen peroxide (P), ozone (Z), It is preferable to combine a known bleaching agent such as peracid and a bleaching aid. For example, the first stage of the multistage bleaching process uses a chlorine dioxide bleaching stage (D) or an ozone bleaching stage (Z), the second stage is an alkali extraction stage (E), the hydrogen peroxide stage (P), the third stage or later. A bleaching sequence using chlorine dioxide or hydrogen peroxide is preferably used. The number of stages after the third stage is not particularly limited, but considering energy efficiency, productivity, etc., it is preferable to finish in three or four stages in total. Further, a chelating agent treatment stage with ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA) or the like may be inserted during the multistage bleaching treatment.

  In producing the fluffed pulp of the present invention, pulp other than sulfite pulp may be mixed. As pulp other than sulfite pulp, dissolved kraft pulp, kraft pulp (conifer bleached kraft pulp (NBKP) or unbleached kraft pulp (NUKP), hardwood bleached kraft pulp (LBKP)) or unbleached kraft pulp (LUKP), etc. ), Mechanical pulp (groundwood pulp (GP), refiner mechanical pulp (RGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), etc.), deinked pulp (DIP), etc. You may mix and use.

  In the fluffed pulp of the present invention, the blending ratio of sulfite pulp with respect to the total pulp content is not particularly limited, but the higher the blending ratio, the lower the internal bond strength in the state of the pulp sheet, so the defibration property is improved. Is done. Moreover, water absorption improves as the blending ratio increases. From that viewpoint, 5 mass% or more is preferable with respect to the absolute dry weight of all the pulp, 30-100 mass% is more preferable, 60-100 mass% is still more preferable. If the blending ratio is less than 5% by mass, it is difficult to improve defibration and water absorption. The water absorption in the present invention is measured according to SCAN-C33: 80 Specific volume and absorption properties. A pulp mat is prepared by molding 3 g of fluffed pulp to a diameter of 50 mm. The water absorption rate (per pulp weight) and the water absorption time when water is absorbed from the bottom surface to the top surface of the pulp mat with a weight of 100 g, 300 g, and 500 g, and the water absorption rate is divided by the water absorption time. It is what. Since the fluffed pulp of the present invention has a feature of high water absorption speed, it can be preferably used for absorbent bodies such as paper diapers.

  The fluffed pulp in the present invention is obtained by fibrillating raw pulp into fibers by mechanical treatment. In the present invention, the moisture content of the pulp before fluffing is preferably 35% or less, more preferably 20% or less, and particularly preferably 10% or less. Although the minimum of a moisture content is not specifically limited, It is about 2% or more. By defibrating the raw pulp in a dry state with a low moisture content, it is difficult to bond between fibers, and fluffed pulp can be obtained efficiently. When the water content exceeds 35%, the effect becomes small. In the present invention, the shape of the raw material pulp is not particularly limited, but it is easy to handle a pulp made into a sheet (so-called pulp sheet) or a pulp made into a sheet like a take-up roll. preferable.

  In the present invention, the apparatus used for mechanical processing for fluffing, that is, defibrating is not particularly limited, but a known defibrator used at the time of manufacturing absorbent materials such as paper diapers can be used, and mechanical A defibrator that uses frictional force or shearing force as the treatment can be suitably used. As an apparatus used for fluffing, for example, a defibrating apparatus having a toothed cylinder can be suitably used (see Japanese Patent No. 2521577). The fluffed pulp of the present invention can be produced simply by defibrating the raw pulp with a toothed cylinder of a defibrating machine, and it is not necessary to cross-link in the fiber by applying a special treatment like the above-mentioned curled fiber. Therefore, a bulky pulp can be easily obtained.

  The use of the fluffed pulp of the present invention is not particularly limited. For example, the absorbent used for a paper diaper, a urine collecting pad, a light incontinence pad, etc., or printing paper such as high-quality or medium-quality printing paper, newsprint paper It can be used for paper for various purposes such as information recording paper, base paper for coated paper, and packaging paper.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by this. In addition, unless otherwise indicated, a part and% represent a mass part and mass%.

The following items were evaluated for the hand-pulped pulp sheets of Examples and Comparative Examples and the fluffed pulps prepared therefrom, and the results are shown in Tables 1 and 2.
Internal bond strength: Measured according to JAPAN-TAPPI 18-2: 2000.
・ Measurement of undefibration rate: Weighing 3.0 g of pulp sheet and using a lab defibrator (AS ONE, small pulverizer SM-1), 75V (100V and 14000 rpm) for 15 seconds. It was fine. The fluffed pulp obtained is taken on a 100 mesh sieve, and a 10 mm diameter tube connected to a dust collector for electric tools (manufactured by Hitachi Koki Co., Ltd., RP 35RYD2, vacuum degree: about 14 kPa) is applied to the sieve under the defibrated pulp. The mass of the undefibrated pulp remaining on the sieve was measured, and the ratio to the original pulp sheet mass (3.0 g) was defined as the undefibration rate.
-Water retention: According to JAPAN-TAPPI 26, the water retention of the fluffed pulp obtained by the method described in <Measurement of undefibrated rate> was measured.
-Water absorption: According to SCAN-C33: 80 (Specific volume and absorption properties), 3 g of the fluffed pulp obtained was molded to a diameter of 50 mm by the method described in <Measurement of undefibration rate> above. A pulp mat was prepared. With a weight of 100 g, 300 g, and 500 g placed on the pulp mat, the water absorption amount and the water absorption time when water was absorbed from the lower surface to the upper surface of the pulp mat were measured, and the water absorption amount was divided by the water absorption time to obtain the water absorption speed. .
-Pulp mat height: The pulp mat was molded into a diameter of 50 mm by the method described in <Water absorption> above, the pulp mat was placed in a cylinder with a scale of 50 mm in diameter, and a pulp with a weight of 100 g placed thereon. The height of the mat was measured.

[Example 1]
Dissolve pulp sheet of sulfite pulp (trade name: NSPP-HR, α cellulose content 95%, fiber length 2.43 mm, manufactured by Nippon Paper Industries Co., Ltd.) using Radiata pine as a raw material according to JIS P 8220-1: 2012 Then, according to JIS P 8222: 1998, a hand-pulled pulp sheet having a basis weight of 250 g / m ² was prepared from the disaggregated pulp. With respect to this handmade pulp sheet, the undefibration rate and the internal bond strength were measured, and the results are shown in Table 1. Further, a fluffed pulp was prepared from the hand-made pulp sheet by the method described in the measurement of the undefibration rate. With respect to the obtained fluffed pulp, the height of the pulp mat, the water retention, the water absorption speed, and the water absorption amount were measured, and the results are shown in Table 2.

[Example 2]
Example 1 except that a sulfite pulp made from red pine (trade name: NT-EX, α-cellulose content 95%, fiber length 2.08 mm, manufactured by Nippon Paper Industries Co., Ltd.) was used. Thus, a hand-made pulp sheet was prepared. With respect to this handmade pulp sheet, the undefibration rate and the internal bond strength were measured, and the results are shown in Table 1. Further, fluffed pulp was prepared from the obtained pulp sheet in the same manner as in Example 1, and the height, water retention, water absorption rate, and water absorption amount of the pulp mat of the obtained fluffed pulp are shown in Table 2.

[Comparative Example 1]
A handmade pulp sheet was prepared in the same manner as in Example 1 except that a kraft pulp (fiber length: 2.35 mm) pulp material made from radiata pine was used. With respect to this handmade pulp sheet, the undefibration rate and the internal bond strength were measured, and the results are shown in Table 1. Further, fluffed pulp was prepared from the obtained pulp sheet in the same manner as in Example 1, and the height, water retention, water absorption rate, and water absorption amount of the pulp mat of the obtained fluffed pulp are shown in Table 2.

  As shown in Table 1, when the pulp sheets of Examples 1 and 2 and Comparative Example 1 are compared, Examples 1 and 2 have lower internal bond strength and lower undefibration rate. It was. Moreover, as shown in Table 2, when the pulp mats of Examples 1 and 2 and Comparative Example 1 were compared, even when the load was increased in Examples 1 and 2, the water absorption amount and the water absorption speed were high. . Moreover, the pulp mat height of Examples 1 and 2 is lower than that of Comparative Example 1, and these characteristics suggest that the fluffed pulp of the present application is a water-absorbing material excellent in water absorption even if it is thin.

Claims (3)

Fluffed pulp obtained by defibrating pulp containing sulphite pulp by mechanical treatment. The fluffed pulp according to claim 1, wherein the sulfite pulp is made from softwood. The fluffed pulp according to claim 2, wherein the conifer is made from radiata pine.