Cellulose pump having excellent particle capture and

Abstract

Provided are: a cellulose pulp having excellent particle trapping properties and adhesion; and a method for producing the cellulose pulp. The pulped fiber is applied to various fields due to excellent capturing properties of functional particles, but has applications that require not only particle capturing properties but also cohesiveness. Pulp-like acrylonitrile-based fibers are known as pulped fibers that give consideration to these characteristics, but in recent years, the influence of plastic waste on the environment becomes a problem, and conversion into a bio-based raw material is required. On the other hand, a conventional cellulose-containing bio-based raw material is not necessarily a satisfactory raw material in consideration of the above-mentioned characteristics. The purpose of the present invention is to provide: a cellulose pulp having excellent particle trapping properties and caking properties; and a method for producing the cellulose pulp. The cellulose pulp is characterized in that the fibril area is 15% or more, and the fibril area (%) / 100 * fine fiber (%) / 100 is 0.05 or more.

Description

Technical Field

[0001] The present invention relates to cellulose pulp having excellent particle-capturing and adhesive properties and a method for producing the same. It should be noted that particle-capturing in the present invention refers to the property of entangling particles without separating them, while adhesiveness refers to the property of connecting the fibers constituting a fiber structure to each other, thereby increasing the strength of the fiber structure. Background Art

[0002] Beaten fibers are characterized by a multi-branched structure and a high specific surface area. They also have excellent adhesive properties and the ability to capture functional particles such as activated carbon. Therefore, they are used in various fields such as papermaking, packaging materials, coatings, building materials, industrial materials, beauty, and health.

[0003] Furthermore, there are uses in which beaten fibers require not only particle-capturing properties but also adhesive properties. As such beaten fibers that achieve both particle-capturing properties and adhesive properties, for example, pulp-like acrylic fibers are known from Patent Document 1.

[0004] Meanwhile, the environmental impact of plastic waste has become a concern in recent years, prompting a shift to bio-based raw materials. However, conventional bio-based raw materials, including cellulose, are not necessarily satisfactory in achieving both the aforementioned particle capture and binding properties.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2021-181669 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] The present invention has been made in view of the above-mentioned state of the prior art, and an object of the present invention is to provide cellulose pulp having excellent particle capturing properties and binding properties, and a method for producing the same.

[0010] Solutions for solving problems

[0011] The present inventors conducted intensive research to achieve the above-mentioned purpose and found that cellulose pulp characterized by a fibril area of ​​15% or more and a fibril area (%) / 100×fine fiber (%) / 100 of 0.05 or more has excellent particle capturing properties and excellent bonding properties, thereby completing the present invention.

[0012] That is, the present invention is achieved by the following means.

[0013] (1) A cellulose pulp characterized in that the fibril area is 15% or more and the fibril area (%) / 100×fine fibers (%) / 100 is 0.05 or more.

[0014] (2) The cellulose pulp according to (1), characterized in that the fine fibers account for 85% or less.

[0015] (3) The cellulose pulp according to (1), characterized in that it is used for capturing particles.

[0016] (4) The cellulose pulp according to (1), characterized in that it is used as a binder.

[0017] (5) A structure using the cellulose pulp described in (1).

[0018] (6) A wet nonwoven fabric using the cellulose pulp described in (1).

[0019] (7) A method for producing cellulose pulp according to (1), characterized in that the cellulose raw material is beaten by a refiner.

[0020] Effects of the Invention

[0021] The cellulose pulp of the present invention is excellent in particle capturing and binding properties and can therefore be suitably used as a raw material for constituting a functional filter or the like carrying functional particles. DETAILED DESCRIPTION

[0022] The raw material for the cellulose pulp of the present invention is not limited as long as it is commonly used as a cellulose pulp raw material. Examples thereof include cellulose-based raw materials such as conifers, broadleaf trees, and bamboo. Raw materials derived from conifers, which have excellent adhesiveness, are preferred. In particular, considering the ease of processing into cellulose pulp having the properties described below and the adhesiveness, bleached kraft pulp (NBKP) derived from conifers is preferably used.

[0023] The cellulose pulp of the present invention preferably has a fibril area (%) / 100×fine fibers (%) / 100 of 0.05 or more, more preferably 0.06 or more. If the ratio is less than 0.05, the particle capturing property and the binding property may be insufficient.

[0024] Here, "fibril area" refers to a property measured by the method described below and is an indicator of the degree of branching in pulp fibers. It should be noted that, although not exact, "fibril area" can be considered to refer to the ratio of the area occupied by branched portions relative to the planar area of ​​the pulp fibers after removing the component corresponding to the "fines" (also referred to as the "fines component") described below. Furthermore, "fines," also a property measured by the method described below, is the ratio of pulp fibers with a fiber length of less than 0.2 mm in the pulp and serves as an indicator of the amount of fines in the pulp.

[0025] In the present invention, the fibril area is preferably 15% or more, more preferably 20% or more. There is no upper limit on the fibril area, but considering the time required for beating the cellulose pulp raw material, it is preferably 30% or less.

[0026] In the present invention, the fine fiber content is preferably 30% or more, more preferably 35% or more. The upper limit of the fine fiber content is preferably 85% or less, more preferably 80% or less. Below the lower limit, the formation of the primary composite (described later) will not proceed. Above the upper limit, the fibril area decreases, preventing the formation of the secondary composite (described later). Consequently, the balance between the fine fiber and fibril areas required for composite formation is disrupted, and satisfactory particle capture and bonding properties may not be achieved.

[0027] The present inventors have discovered that a larger product of the fibril area (%) and fines (%) tends to achieve a better balance between particle capture and binding properties. The reason for this is unclear, but it is speculated that the fines with a large specific surface area initially entangle particles, forming a primary complex of a certain size. The components with a large fibril area then bind this primary complex, stabilizing it as a secondary and tertiary complex, thereby improving particle capture.

[0028] The cellulose pulp of the present invention is obtained by beating a cellulose-based raw material. The method of the beating treatment is not limited, and beating equipment such as a beater, a refiner, and a high-pressure homogenizer can be used. Among them, the beating treatment by a refiner is preferred. The beating treatment by a refiner suppresses the excessive rise of fine fibers and easily increases the fibril area. Therefore, a cellulose pulp with a fibril area of ​​15% or more and a fibril area (%) / 100×fine fiber (%) / 100 of 0.05 or more can be obtained with high productivity. It should be noted that in the present invention, the cellulose raw material does not need to be treated with an enzyme such as cellulase to promote beating before the beating treatment.

[0029] The conditions for beating treatment with a refiner are not limited, but the shape of the refiner blade, the treatment flow rate, the gap, etc. need to be adjusted so that the fibril area (%) / 100×fine fibers (%) / 100 becomes 0.05 or more.

[0030] The cellulose pulp of the present invention has excellent particle-capturing and adhesive properties and can therefore be used alone or in combination with other raw materials as a structure useful in a variety of applications. In order to achieve the effects of the cellulose pulp of the present invention, the cellulose pulp of the present invention is preferably present in an amount of 5% by weight or more, more preferably 10% by weight or more, and even more preferably 20% by weight or more in such a structure.

[0031] The external form of the structure includes paper, sheet, laminate, spherical, cylindrical molded bodies, etc. The cellulose pulp of the present invention may be contained in the structure in the following forms: a substantially uniform distribution of the cellulose pulp by mixing with other raw materials such as fibers and resin compositions; a concentrated distribution in any layer (either a single layer or multiple layers) in the case of a multi-layer structure; or a distribution in each layer at a specific ratio.

[0032] The appearance, content, other raw materials constituting the structure, and other components combined with the structure of the above-mentioned example should be appropriately determined based on the functions, characteristics, and shape required for the type of final product (for example, diffusion layers and absorption layers of sanitary products (diapers, urine-absorbing pads, sanitary napkins, etc.), carbon sheets for fuel cell diffusion membranes, water purification filters, activated carbon-supported sheets, filters, binders for papermaking, papermaking products, wet friction materials, etc.), and the manner in which the cellulose pulp of the present invention contributes to the realization of the above-mentioned functions.

[0033] It should be noted that the properties of the cellulose pulp of the present invention can be effectively utilized in the aforementioned applications. For example, in applications such as absorbent layers of sanitary products and activated carbon-supported sheets, the particle-capturing properties can be used to immobilize water-absorbing resin and activated carbon particles. Furthermore, in applications such as diffusion layers of sanitary products, the hydrophilicity of the fibrils can improve the diffusibility of urine and other substances.

[0034] Example

[0035] The following examples are provided to facilitate understanding of the present invention. However, these examples are merely illustrative and the present invention is not limited thereto. In the examples, parts and percentages are expressed by weight unless otherwise specified. The various properties were measured using the following methods.

[0036] <Adhesion>

[0037] A water slurry was prepared with a weight ratio of 30 / 70 of the beaten sample / acrylic short fibers (fineness 0.4 dtex, fiber length 3.0 mm) and a square sheeter manufactured by Kumagai Riki Kogyo Co., Ltd. was used to prepare a slurry with a unit area weight of 50 g / m 2 Paper was made using a calender and dried using a heat calender to produce paper for evaluation. The resulting paper was cut into 2 cm (W) x 10 cm (L) pieces and measured for breaking strength using a tensile testing machine (RTA500 (U-1573) manufactured by A&D) at a pulling speed of 2 cm / min. A greater breaking strength indicates better adhesion. It should be noted that a strength of 20 N or greater was considered sufficient.

[0038] <Particle Capture>

[0039] 1 g of the slurried sample (in terms of solid content) was added to 1 L of pure water and stirred. 6 g of powdered activated carbon (Burokoru B-printed activated carbon manufactured by Taihei Chemical Industry Co., Ltd. / average particle size 90 μm) was added and stirred for 30 minutes. 2 ) was filtered, and the weight (A [g]) of the sample under the sieve after drying at 105°C for 5 hours was measured. The amount of activated carbon captured per 1g of sample was calculated according to the following formula. It should be noted that a particle capture rate of 30% or more was considered to be sufficient.

[0040] Particle capture (%) = A / 6×100

[0041] <Fibril area, fine fibers>

[0042] The measurement was performed using Fiber Tester Plus manufactured by Lorentzen & Wettre.

[0043] <Examples 1 to 5, Comparative Examples 1 to 4>

[0044] NBKP was beaten using a refiner while adjusting the number of passes and the gap of the refiner to obtain cellulose pulps of Examples 1 to 5 and Comparative Examples 1 to 4 having different fibril areas and fine fibers.

[0045] <Comparative Example 5>

[0046] The NBKP used above was evaluated.

[0047] Table 1 shows the evaluation results of the cellulose pulp obtained in the above-mentioned Examples and Comparative Examples.

[0048] [Table 1]

[0049]

[0050] As shown in Table 1, it can be seen that Examples 1 to 5 have good adhesiveness and particle capturing properties. On the other hand, it can be seen that Comparative Examples 1 to 5 cannot achieve both adhesiveness and particle capturing properties.

Claims

1. A cellulose pulp, characterized in that The fibril area is 15% or more, and the fibril area (%) / 100×fine fibers (%) / 100 is 0.05 or more.

2. The cellulose pulp according to claim 1, characterized in that The fine fibers are less than 85%.

3. The cellulose pulp according to claim 1, characterized in that It is used to capture particles.

4. The cellulose pulp according to claim 1, characterized in that It is used as a binder.

5. A structure comprising the cellulose pulp according to claim 1. A wet nonwoven fabric using the cellulose pulp according to claim 1.

7. A method for producing cellulose pulp according to claim 1, characterized in that: The cellulose raw material is beaten by a refiner.

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