JP6640606B2 - Non-woven - Google Patents

Description

  The present invention relates to a nonwoven fabric. More specifically, the present invention relates to a nonwoven fabric having deodorant and antibacterial functions.

  In general, a nonwoven fabric is obtained by laminating fibers including synthetic fibers without weaving and spreading them in a sheet shape, and bonding the fibers appropriately by an appropriate method. Nonwoven fabrics can be mass-produced at low cost because there is no spinning, weaving or knitting process like cloth. In addition, by combining raw materials, manufacturing methods, and other materials, it is easy to adjust various functions, such as porous permeability and filterability, which are structural features of the nonwoven fabric, according to required quality. It is. Due to these characteristics, nonwoven fabrics are used for sanitary products such as diapers, sanitary products, wipers, masks, etc., filters for filtering gas or liquid, construction materials and civil engineering applications such as roofing materials (roofing materials), automotive interior materials, clothing, etc. Widely used in various fields.

In the use of the nonwoven fabric described above, in addition to mechanical properties such as tensile strength and tear strength required for the whole nonwoven fabric, deodorant and / or antibacterial functions are often required. For example, in the use of sanitary goods such as diapers, malodor components such as ammonia, trimethylamine, hydrogen sulfide, and methyl mercaptan (smell of human waste, odor of feces, putrefaction odor, etc.), which are so-called four major malodors, are effectively removed. And it is required to suppress it continuously.
In addition, in filter applications, in addition to appropriate air permeability and particle collecting properties required for filters in general, the above-mentioned deodorizing function, and especially the growth and growth of mold and hyphae when used under high humidity. Effective and continuous suppression is required.

  Various methods have been proposed to impart these deodorant and antibacterial functions. In Patent Documents 1 and 2, one aqueous solution of a silicon compound or an aluminum compound, which is a component of zeolite, is impregnated into a hydrophilic polymer base material such as a cellulosic fiber, and a basic substance and the other aqueous solution are mixed. There has been proposed an inorganic porous crystal-hydrophilic polymer composite in which the material is further impregnated and zeolite is supported inside the cellulosic fiber. Further, it is disclosed that an antibacterial effect and a deodorizing effect can be imparted by supporting a metal on the zeolite.

  Further, Patent Document 3 discloses that an aqueous solution containing a silicon compound and a basic substance and an aqueous solution containing an aluminum compound and a basic substance are impregnated into a fibrous structure, and then heated and heated with wet heat to make the silicon compound and the aluminum inside the cellulosic fiber. A cellulosic fibrous structure that reacts with a compound to produce zeolite that is a silica-alumina porous body is disclosed. Further, it is disclosed that antibacterial properties and fungicidal properties can be imparted by introducing metal ions into the silica-alumina porous material.

  Patent Document 4 discloses an antibacterial cellulosic fiber containing one or two or more silver antibacterial agents selected from silver zeolite, silver zirconium phosphate, silver calcium phosphate, and silver-soluble glass. Further, a nonwoven fabric using the antibacterial cellulosic fiber is disclosed.

  Patent Document 5 discloses a paper base material containing oxidized pulp, wherein the amount of carboxyl groups in the oxidized pulp is 1.0 mmol / g to 2.0 mmol / g based on the absolute dry weight of the oxidized pulp. A paper substrate is disclosed, and it is also described that the paper substrate contains a certain range of fibers produced from a synthetic resin.

JP-A-10-120923 JP-A-11-315492 JP 2008-031591 A JP-A-11-107033 International Publication No. 2014/099729

However, Patent Documents 1 to 4 disclose only a simple mixture of a cellulosic fiber and an inorganic compound containing a metal component, and the cellulosic fiber and the inorganic compound containing a metal component are chemically strongly bonded. Not necessarily. In other words, inorganic compounds containing a metal component do not form a physical or chemical network like fibers, so when a nonwoven fabric is manufactured using this, the mechanical properties of the base material, such as tensile strength and tear strength, are reduced. In addition, there is a problem that the inorganic compound containing the metal component falls off from the base material.
Further, there is a problem that the deodorizing and antibacterial effects are reduced when the nonwoven fabric is placed in a high humidity environment or when it is wet. Here, the term “wet” refers to, for example, a state where the nonwoven fabric contains water at a mass ratio of 100% or more with respect to a constant mass after drying.
Further, the paper substrate described in Patent Document 5 does not have a sufficient deodorizing effect.

  Accordingly, an object of the present invention is to provide a nonwoven fabric which has good mechanical properties, can suppress the deodorant and antibacterial components from falling off, and has a deodorant and antibacterial effect independent of humidity and secured even when wet.

In order to achieve the above object, the nonwoven fabric of the present invention is characterized in that Ag, Au, Pt, Pd, Ni, Mn, Fe, Ti, Al, Zn are used for a cellulosic fiber having a carboxyl group or a carboxylate group on the surface. And a nonwoven fabric containing a metal ion-containing cellulosic fiber containing at least one metal ion selected from the group consisting of Cu and Cu, and a synthetic fiber, further comprising a cellulosic fiber not containing the metal ion .

In the metal ion-containing cellulosic fiber, it is preferable that a part of the hydroxyl group at the C6 position in the glucose unit of cellulose is oxidized to a carboxyl group.
Preferably, the metal ions are Ag ions or Cu ions .

  ADVANTAGE OF THE INVENTION According to this invention, the nonwoven fabric which has favorable mechanical characteristics, can suppress the deodorant / antibacterial component from falling off, and ensures the deodorant / antibacterial effect regardless of humidity and even when wet is obtained.

  The nonwoven fabric according to the embodiment of the present invention is based on a cellulosic fiber having a carboxyl group or a carboxylate group on the surface, from the group of Ag, Au, Pt, Pd, Ni, Mn, Fe, Ti, Al, Zn and Cu. It includes a metal ion-containing cellulosic fiber containing one or more selected metal ions, and a synthetic fiber. The details will be described below.

<1. Cellulose fiber containing metal ions>
The nonwoven fabric according to the embodiment of the present invention is selected from the group consisting of Ag, Au, Pt, Pd, Ni, Mn, Fe, Ti, Al, Zn, and Cu, for a cellulosic fiber having a carboxyl group or a carboxylate group. Metal-containing cellulosic fibers containing one or more metal ions are included.
The content of the metal ion-containing cellulosic fiber is preferably 1% by mass or more based on the nonwoven fabric. When the content is less than 1% by mass, a sufficient deodorant / antibacterial effect may not be provided. The upper limit of the content is not particularly limited and can be appropriately adjusted according to the degree of the deodorant / antibacterial effect required. However, from the viewpoint of cost and the like, the upper limit can be, for example, 95% by mass.

<2. Cellulose-based fiber not containing metal ions>
The nonwoven fabric according to the embodiment of the present invention is characterized in that, in addition to the above-mentioned metal ion-containing cellulosic fibers, cellulosic fibers containing no metal ions (hereinafter, referred to as “general cellulosic fibers”) absorb moisture, absorb water, and feel. May be contained depending on the function required.
General cellulosic fibers include, for example, wood pulp; non-wood such as bamboo, cotton, hemp, jute, kenaf, agricultural waste, animal (eg, ascidian), algae, and microorganism (eg, acetic acid bacteria (Acetobacter)) products. Pulp;
As the general cellulosic fibers, wood pulp is preferable, and one or more general cellulosic fibers can be used in combination.

  The content of the metal ion-containing cellulosic fiber is preferably 1% by mass or more, and the content of a synthetic fiber described later is preferably 5% by mass or more. It is preferable that the amount is 94% by mass or less. The lower limit of the content of general cellulosic fibers is not particularly limited, and may not include general cellulosic fibers.

The metal ion-containing cellulosic fiber, and the general cellulosic fiber, the number average fiber diameter and the number average fiber length are not particularly limited, mechanical properties such as required tensile strength and tear strength, air permeability, Any value can be used depending on the texture or the like. Further, two or more kinds of fibers having different number average fiber diameters and number average fiber lengths may be mixed and used at an arbitrary ratio.
For example, in the case of softwood kraft pulp (NBKP), which is one of natural cellulose fibers, the number average fiber diameter is about 30 to 60 μm, the number average fiber length is about 3 to 5 mm, and in the case of hardwood bleached kraft pulp (LBKP), The average fiber diameter is about 10 to 30 μm, and the number average fiber length is about 1 to 2 mm.

The metal ion-containing cellulosic fiber and the general cellulosic fiber may be subjected to beating treatment one or more times in the production process until both are contained in the nonwoven fabric. Here, the beating treatment is a treatment for applying a mechanical shearing force to the fiber. By the beating treatment, a part of the cellulosic fiber is converted into fibrillated or nanofiber, and the mechanical properties such as tensile strength are improved.
In particular, in the case of a metal ion-containing cellulosic fiber, the beating treatment can further enhance the deodorizing effect and the antibacterial effect after the metal ion is supported.

As an index of the degree of beating, freeness (CSF) is generally used. The freeness of the metal ion-containing cellulosic fiber is preferably in the range of 30 to 600 ml.
When the freeness is lower than 30 ml, the yield into the nonwoven fabric decreases in the nonwoven fabric manufacturing process, and when the freeness is higher than 600 ml, the fibrillation is insufficient, so that the deodorizing and antibacterial effects are obtained. May decrease.
Further, the freeness of the general cellulosic fiber is not particularly limited, and can be freely selected from a range of a general freeness, for example, a range of 5 to 950 ml according to a desired quality.

  The device used for beating is not particularly limited, and a known device can be used arbitrarily. Examples of beating machines include refiners, beaters, PFI mills, kneaders, dispersers, etc., in which metal or blades and pulp fibers act around the rotation axis, friction between pulp fibers, high-pressure homogenizers, ultra-high-pressure homogenizers , A nanomizer, various mills, and a mill-type grinder.

<3. Production of cellulosic fibers containing metal ions>
The above-mentioned metal ion-containing cellulosic fiber is obtained by introducing a carboxyl group or a carboxylate group into a glucose unit on the surface by chemically modifying a general cellulosic fiber as follows, and then further supporting a metal ion. Can be manufactured.
Hereinafter, a method of introducing a carboxyl group or a carboxylate group into a glucose unit on the surface of a cellulosic fiber and a method of supporting a metal ion thereafter will be described.

<3-1. Introduction of carboxyl group or carboxylate group>
Cellulose has three hydroxyl groups per glucose unit and can be subjected to various chemical denaturation treatments. In the present invention, at least a part of the cellulosic fiber is modified to introduce a carboxyl group or a carboxylate group in a step described later.
Here, the carboxyl group refers to a group represented by -COOH, and the carboxylate group refers to a group represented by -COO-. The carboxylate group counter ion is not particularly limited. In addition, a carboxyl group or a carboxylate group is collectively called an "acid group".

  The content of the acid group can be measured by the method disclosed in paragraph 0021 of JP-A-2008-001728. That is, 60 mL of a 0.5 to 1% by mass slurry is prepared using a precisely weighed dry cellulose sample, and the pH is adjusted to about 2.5 with a 0.1 mol / L aqueous hydrochloric acid solution. Thereafter, a 0.05 mol / L aqueous solution of sodium hydroxide is dropped to measure the electric conductivity. The measurement is continued until the pH is about 11. From the amount (V) of sodium hydroxide consumed until the change in the electrical conductivity indicates a gradual neutralization step of the weak acid, the amount X1 of the acid group is determined using the following equation.

X1 (mmol / g) = V (mL) × 0.05 / mass of cellulosic fiber (g)
The amount of the acid group of the cellulosic fiber is preferably 0.1 to 3.0 mmol / g. When the amount of the acid group is less than 0.1 mmol / g, the amount of metal particles present on the surface of the cellulosic fiber in the step of supporting metal ions described below is insufficient, and the deodorizing and antibacterial functions may be inferior. is there. On the other hand, when the amount of the acid group exceeds 3.0 mmol / g, aggregation of the metal particles occurs, and similarly, the deodorizing and antibacterial functions may be inferior.

  The modification method for introducing a carboxyl group or a carboxylate group is not particularly limited as long as the cellulosic fiber after modification contains a carboxyl group or a carboxylate group. , Phosphorylation, esterification, silane coupling, fluorination, and cationization. In particular, oxidation (carboxylation) and etherification are preferred. Hereinafter, these will be described in detail.

<3-1-1. Oxidation>
In the present invention, the method for oxidizing the cellulosic fiber is not particularly limited, and a known method can be used. One example is a method of oxidizing a cellulose raw material in water using an oxidizing agent in the presence of a substance selected from the group consisting of N-oxyl compounds, bromides, iodides, and mixtures thereof. According to this method, the primary hydroxyl group at the C6 position of the glucopyranose ring on the cellulose surface is selectively oxidized to generate a group selected from the group consisting of an aldehyde group, a carboxyl group, and a carboxylate group. The concentration of the cellulose raw material during the reaction is not particularly limited, but is preferably 5% by mass or less.

  An N-oxyl compound refers to a compound that can generate a nitroxy radical. Examples of the nitroxyl radical include 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO). As the N-oxyl compound, any compound can be used as long as it promotes a desired oxidation reaction.

  The amount of the N-oxyl compound used is not particularly limited as long as it is a catalytic amount capable of oxidizing the cellulosic fiber. For example, the amount is preferably 0.01 mmol or more, more preferably 0.02 mmol or more, based on 1 g of absolutely dried cellulose. The upper limit is preferably 10 mmol or less, more preferably 1 mmol or less, and still more preferably 0.5 mmol or less. Therefore, the amount of the N-oxyl compound used is preferably 0.01 to 10 mmol, more preferably 0.01 to 1 mmol, and even more preferably 0.02 to 0.5 mmol, based on 1 g of absolutely dried cellulose.

  Bromide is a compound containing bromine, and examples thereof include an alkali metal bromide that can be dissociated and ionized in water, such as sodium bromide. Further, iodide is a compound containing iodine, and examples thereof include alkali metal iodide. The amount of bromide or iodide used may be selected within a range that can promote the oxidation reaction. The total amount of bromide and iodide is preferably 0.1 mmol or more, more preferably 0.5 mmol or more, based on 1 g of absolutely dried cellulose. The upper limit is preferably 100 mmol or less, more preferably 10 mmol or less, and even more preferably 5 mmol or less. Therefore, the total amount of bromide and iodide is preferably 0.1 to 100 mmol, more preferably 0.1 to 10 mmol, and even more preferably 0.5 to 5 mmol, based on 1 g of absolutely dried cellulose.

The oxidizing agent is not particularly restricted but includes, for example, halogen, hypohalous acid, halogenous acid, perhalic acid, salts thereof, halogen oxides and peroxides. In particular, hypohalous acid or a salt thereof is preferable, hypochlorous acid or a salt thereof is more preferable, and sodium hypochlorite is further preferable because it is inexpensive and has less environmental load.
The amount of the oxidizing agent used is preferably 0.5 mmol or more, more preferably 1 mmol or more, and even more preferably 3 mmol or more, based on 1 g of absolutely dried cellulose. The upper limit is preferably 500 mmol or less, more preferably 50 mmol or less, and even more preferably 25 mmol or less.

Therefore, the amount of the oxidizing agent used is preferably 0.5 to 500 mmol, more preferably 0.5 to 50 mmol, still more preferably 1 to 25 mmol, and most preferably 3 to 10 mmol, based on 1 g of absolutely dried cellulose.
When an N-oxyl compound is used, the amount of the oxidizing agent used is preferably 1 mol or more per 1 mol of the N-oxyl compound, and the upper limit is preferably 40 mol. Therefore, the use amount of the oxidizing agent is preferably 1 to 40 mol per 1 mol of the N-oxyl compound.

Conditions such as pH and temperature during the oxidation reaction are not particularly limited, and the oxidation reaction generally proceeds efficiently even under relatively mild conditions. The reaction temperature is preferably at least 4 ° C, more preferably at least 15 ° C. The upper limit is preferably 40 ° C. or lower, more preferably 30 ° C. or lower. Therefore, the temperature is preferably 4 to 40 ° C, and may be about 15 to 30 ° C, that is, room temperature.
The pH of the reaction solution is preferably 8 or more, more preferably 10 or more. The upper limit is preferably 12 or less, more preferably 11 or less. Therefore, the pH of the reaction solution is preferably about 8 to 12, and more preferably about 10 to 11.
Usually, a carboxyl group is generated in cellulose as the oxidation reaction proceeds, so that the pH of the reaction solution tends to decrease. Therefore, in order to allow the oxidation reaction to proceed efficiently, it is preferable to add an alkaline solution such as an aqueous sodium hydroxide solution to maintain the pH of the reaction solution in the above range. As a reaction medium at the time of oxidation, water is preferable because of its easy handling properties and the difficulty of side reactions.

  The reaction time in the oxidation can be appropriately set according to the degree of progress of the oxidation, and is usually 0.5 hour or more. The upper limit is usually 6 hours or less, preferably 4 hours or less. Therefore, the reaction time in the oxidation is usually 0.5 to 6 hours, for example, about 0.5 to 4 hours.

  The oxidation may be performed in two or more stages of the reaction. For example, by oxidizing the oxidized cellulose obtained by filtration after the completion of the first-stage reaction again under the same or different reaction conditions, the efficiency can be reduced without being inhibited by the salt produced as a by-product in the first-stage reaction. Can be well oxidized.

Another example of the carboxylation (oxidation) method includes a method of oxidizing by ozone treatment. By this oxidation reaction, at least the hydroxyl groups at the 2- and 6-positions of the glucopyranose ring constituting cellulose are oxidized, and the cellulose chain is decomposed.
The ozone treatment is usually performed by bringing a gas containing ozone into contact with a cellulose raw material. The ozone concentration in the gas is preferably 50 g / m3 or more. The upper limit is preferably 250 g / m3 or less, and more preferably 220 g / m3 or less. Therefore, the ozone concentration in the gas is preferably from 50 to 250 g / m3, more preferably from 50 to 220 g / m3.

The amount of ozone added is preferably at least 0.1 part by mass, more preferably at least 5% by mass, based on 100% by mass of the solid content of the cellulose raw material. The upper limit is usually 30% by mass or less. Therefore, the amount of ozone added is preferably 0.1 to 30% by mass, more preferably 5 to 30% by mass, based on 100% by mass of the solid content of the cellulose raw material.
The ozone treatment temperature is usually 0 ° C. or higher, preferably 20 ° C. or higher. The upper limit is usually 50 ° C. or less. Therefore, the ozone treatment temperature is preferably from 0 to 50 ° C, more preferably from 20 to 50 ° C.
The ozone treatment time is usually at least 1 minute, preferably at least 30 minutes. The upper limit is usually 360 minutes or less. Therefore, the ozone treatment time is usually about 1 to 360 minutes, preferably about 30 to 360 minutes.
When the conditions of the ozone treatment are within the above-mentioned range, excessive oxidation and decomposition of cellulose can be prevented, and the yield of oxidized cellulose is improved.

  The resulting product obtained after the ozone treatment may be further subjected to an additional oxidation treatment using an oxidizing agent. The oxidizing agent used for the additional oxidation treatment is not particularly limited, and examples thereof include chlorine-based compounds such as chlorine dioxide and sodium chlorite; oxygen, hydrogen peroxide, persulfuric acid, and peracetic acid. As a method of the antioxidant treatment, for example, a method in which these oxidizing agents are dissolved in a polar organic solvent such as water or alcohol to prepare an oxidizing agent solution, and the cellulose raw material is immersed in the oxidizing agent solution may be mentioned.

  The amounts of carboxyl groups, carboxylate groups, and aldehyde groups contained in the oxidized cellulose fibers can be adjusted by controlling the oxidizing conditions such as the amount of the oxidizing agent added and the reaction time.

<3-1-2. Etherification>
As the etherification, any method may be used as long as it contains a carboxyl group or a carboxylate group in the functional group after the reaction, for the sake of introducing metal ions into the cellulosic fiber in a later step, and a known method is used. be able to. Examples include carboxyalkyl etherification such as carboxymethyl (ether) conversion, carboxyethyl (ether) conversion, carboxypropyl (ether) conversion, carboxybutyl (ether) conversion, and carboxyphenyl (ether) conversion. . The carboxymethylation method will be described below as an example.

The method of carboxymethylation is not particularly limited, and a known method can be used. For example, there is a method of mercerizing a cellulose raw material as a starting material and then etherifying the raw material. A common solvent is used for the carboxymethylation reaction. Examples of the solvent include water, alcohol (for example, lower alcohol), and a mixed solvent thereof. Examples of the lower alcohol include methanol, ethanol, N-propyl alcohol, isopropyl alcohol, N-butanol, isobutanol, and tertiary butanol.
The mixing ratio of the lower alcohol in the mixed solvent is usually 60% by mass or more or 95% by mass or less, and preferably 60 to 95% by mass. The amount of the solvent is usually 3 times the mass of the cellulose raw material. The upper limit is not particularly limited, but is 20 times by mass. Therefore, the amount of the solvent is preferably 3 to 20 times by mass.

  Mercerization is usually performed by mixing a bottoming material and a mercerizing agent. Examples of the mercerizing agent include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide. The amount of the mercerizing agent used is preferably 0.5 times or more, more preferably 1.0 times or more, and even more preferably 1.5 times or more per anhydroglucose residue of the starting material. The upper limit is usually 20 times or less, preferably 10 times or less, more preferably 5 times or less, and therefore preferably 0.5 to 20 times, more preferably 1.0 to 10 times, and more preferably 1 to 10 times. More preferably, the molar amount is 0.5 to 5 times.

  The reaction temperature for mercerization is usually 0 ° C. or higher, preferably 10 ° C. or higher. The upper limit is usually at most 70 ° C, preferably at most 60 ° C. Therefore, the reaction temperature is usually 0 to 70 ° C, preferably 10 to 60 ° C. The reaction time is usually at least 15 minutes, preferably at least 30 minutes. The upper limit is usually 8 hours or less, preferably 7 hours or less. Therefore, it is usually 15 minutes to 8 hours, preferably 30 minutes to 7 hours.

The etherification reaction is usually performed by adding a carboxymethylating agent to the reaction system after mercerization. Examples of the carboxymethylating agent include sodium monochloroacetate. The amount of the carboxymethylating agent to be added is usually preferably 0.05 times or more, more preferably 0.5 times or more, further preferably 0.8 times or more, per glucose residue of the cellulose raw material. The upper limit is usually 10.0 times or less, preferably 5 times or less, more preferably 3 times or less, and therefore preferably 0.05 to 10.0 times, and more preferably 0.5 to 10.0 times. 5, more preferably 0.8 to 3 moles.
The reaction temperature is usually 30 ° C. or higher, preferably 40 ° C. or higher, and the upper limit is usually 90 ° C. or lower, preferably 80 ° C. or lower. Therefore, the reaction temperature is usually 30 to 90 ° C, preferably 40 to 80 ° C. The reaction time is usually at least 30 minutes, preferably at least 1 hour. The upper limit is usually 10 hours or less, preferably 4 hours or less. Therefore, the reaction time is usually 30 minutes to 10 hours, preferably 1 hour to 4 hours.
The reaction solution may be stirred during the carboxymethylation reaction, if necessary.

  When the cellulose raw material is modified by carboxymethylation, the degree of carboxymethyl substitution per anhydroglucose unit in the obtained carboxymethylated cellulosic fiber is preferably 0.01 or more, more preferably 0.05 or more, and 0.10 or more. More preferably, it is the above. The upper limit is preferably equal to or less than 0.50, more preferably equal to or less than 0.40, and still more preferably equal to or less than 0.35. Therefore, the degree of carboxymethyl group substitution is preferably 0.01 to 0.50, more preferably 0.05 to 0.40, and still more preferably 0.10 to 0.30.

The carboxymethyl substitution degree per glucose unit of the carboxymethylated cellulosic fiber can be measured, for example, by the following method. That is, 1) About 2.0 g of carboxymethylated cellulose (absolutely dried) is precisely weighed and placed in a 300 mL Erlenmeyer flask with a stopper. 2) 100 mL of special-grade concentrated nitric acid is added to 1000 mL of methanol, 100 mL of a methanol nitrate solution obtained is added, and the mixture is shaken for 3 hours to convert the carboxymethyl cellulose salt (carboxymethylated cellulose) into a hydrogenated carboxymethylated cellulose. 3) 1.5 to 2.0 g of hydrogenated carboxymethylated cellulose (absolutely dried) is precisely weighed and placed in a 300 mL Erlenmeyer flask with a stopper. 4) Wet the hydrogenated carboxymethylated cellulose with 15 mL of 80% methanol, add 100 mL of 0.1 N NaOH, and shake for 3 hours at room temperature. 5) Back titrate excess NaOH with 0.1 N H2SO4 using phenolphthalein as indicator. 6) The degree of carboxymethyl substitution (DS) is calculated by the following equation:
A = [(100 × F ′ − (0.1 N H 2 SO 4) (mL) × F) × 0.1] / (absolute dry mass of hydrogenated carboxymethylated cellulose (g))
DS = 0.162 × A / (1-0.058 × A)
A: 1N NaOH amount (mL) required for neutralization of 1 g of hydrogenated carboxymethylated cellulose
F ': Factor of 0.1N NaOH F: Factor of 0.1N H2SO4

<3-2. Loading of metal ions>
For a cellulosic fiber containing a carboxyl group or a carboxylate group, ions of at least one metal element selected from the group consisting of Ag, Au, Pt, Pd, Ni, Mn, Fe, Ti, Al, Zn and Cu Alternatively, by carrying the nanoparticles, a high deodorizing effect is exhibited. Particularly, by using Ag and Cu, the antibacterial function is further improved.
In the present invention, since this metal ion and the cellulosic fiber are chemically strongly bonded, when contained in the nonwoven fabric, the metal component is hardly detached from the nonwoven fabric, and the mechanical properties such as tensile strength are also good. is there.

The method for supporting the metal ions on the cellulosic fiber is not particularly limited. For example, a dispersion of the cellulosic fiber prepared in advance and a metal compound aqueous solution may be mixed, or the cellulosic fiber may be mixed. The dispersion may be applied onto a substrate to form a film, and the film may be impregnated with an aqueous solution of a metal compound. At this time, the film may be fixed on the substrate or may be separated from the substrate.
Although the details are unknown, by these methods, the metal ion derived from the metal compound forms an ionic bond with the carboxylate group, or by coordination, when the metal ion is added to the cellulosic fiber Conceivable.

Here, the aqueous metal compound solution is an aqueous solution of a metal salt. Examples of metal salts include complexes (complex ions), halides, nitrates, sulfates, and acetates. The concentration of the aqueous metal compound solution is not particularly limited, but is preferably in the range of 10 to 80% by mass, more preferably 30 to 60% by mass, based on 100 parts by mass of the cellulosic fiber. The time for contacting the metal compound may be appropriately adjusted.
The temperature at the time of contact is not particularly limited, but is preferably in the range of 2 to 50 ° C. Further, the pH of the solution at the time of contacting is not particularly limited, but if the pH is low, it is difficult for a metal ion to bind to a carboxyl group, so it is preferably in the range of 7 to 13, and more preferably in the range of 8 to 12. Is particularly preferred.

In the present invention, metal ions can be introduced into the cellulosic fiber as described above, but a part of the metal ions may be reduced to metal nanoparticles. Also, if necessary, a part of the metal ions bonded to the metal ion-carrying cellulosic fiber may be reduced by adding a reducing agent or the like to partially form metal nanoparticles on the surface of the cellulosic fiber. Is also possible.
However, it is preferred from the viewpoint of the deodorizing effect that the entire amount of the metal compound is used as it is as the metal ion without performing a special reduction treatment.

  The fact that the cellulosic fiber contains metal ions can be confirmed by a scanning electron microscope image and ICP emission analysis of the extract with a strong acid. That is, the presence of metal ions cannot be confirmed in the scanning electron microscope image, while the presence of the metal can be confirmed in ICP emission analysis. On the other hand, for example, when the metal is reduced from ions and exists as metal particles, the presence of metal ions can be determined because the metal particles can be confirmed by a scanning electron microscope image. The presence or absence of metal ions can also be determined by scanning electron microscope images and element mapping. That is, although the metal ion cannot be confirmed in the scanning electron microscope image, the presence of the metal ion can be confirmed by performing element mapping.

  In the step of supporting the metal ions, the content of the metal ions with respect to the cellulosic fiber is preferably in the range of 10 to 60 mg / g, and more preferably in the range of 15 to 55 mg / g. Preferably, it is particularly preferably in the range of 20 to 50 mg / g. If it is less than 10 mg / g, the deodorant and antibacterial functions may be inferior. On the other hand, when it exceeds 60 mg / g, aggregation of metal particles occurs, and the deodorizing and antibacterial functions may be similarly deteriorated.

<4. Synthetic fiber>
The nonwoven fabric according to the embodiment of the present invention includes at least one kind of synthetic fiber, that is, a fiber made of a synthetic resin obtained by polymerizing a low organic molecule such as petroleum. In general, synthetic fibers are inferior in the hygroscopicity, water absorbency, flexibility and the like as compared with the above-mentioned cellulose fibers, but are excellent in dimensional stability and light resistance.
The content of the synthetic fibers is preferably 5% by mass or more based on the nonwoven fabric from the viewpoint of dimensional stability. Further, since the content of the metal ion-containing cellulosic fiber is preferably 1% by mass or more based on the nonwoven fabric, the content of the synthetic fiber is preferably 99% by mass or less based on the nonwoven fabric.

  The type of the synthetic fiber is not particularly limited. For example, polyester fibers such as polyethylene terephthalate (PET) fiber, polybutylene terephthalate (PBT) fiber, polyethylene naphthalate (PEN), polyethylene isophthalate (PEI) fiber, and polypropylene ( PP) fiber, polyethylene (PE) fiber, polyolefin fiber such as ethylene-vinyl alcohol copolymer fiber, ethylene-vinyl acetate copolymer fiber, polyacryl fiber, polyamide fiber, polyvinyl alcohol (PVA) fiber, polylactic acid (PLA) fiber, polyester copolymer resin-polyester resin, polyethylene resin-polyester resin, ethylene / vinyl alcohol copolymer resin-polyester resin, polyester copolymer resin-polypropylene resin, poly Styrene resins - polypropylene resins, ethylene-vinyl alcohol copolymer resin - polypropylene resins, ethylene-vinyl acetate copolymer resins - such as composite fibers and polypropylene resin.

<5. Other materials>
The nonwoven fabric of the present invention may contain one or more other materials, if necessary, in addition to the metal ion-containing cellulosic fiber, general cellulosic fiber, and synthetic fiber. The type of the other material is not particularly limited, for example, heat stabilizers, stabilizers such as weathering stabilizers, fillers, antistatic agents, slip agents, antiblocking agents, antifogging agents, lubricants, dyes, pigments , Natural oils, synthetic oils, waxes and the like. These may be used alone or in combination of two or more. The total content of these materials is preferably within a range not exceeding 10% by mass with respect to the nonwoven fabric.

  Examples of the stabilizer include an antioxidant such as 2,6-di-t-butyl-4-methyl-phenol (BHT); and tetrakis [methylene-3- (3,5-di-t-butyl-4-). Hydroxyphenyl) propionate] methane, β- (3,5-di-t-butyl-4-hydroxyphenyl) propionic acid alkyl ester, 2,2′-oxamidobis [ethyl-3- (3,5-di-t- Butyl-4-hydroxyphenyl) propionate], a phenolic antioxidant; fatty acid metal salts such as zinc stearate, calcium stearate, calcium 1,2-hydroxystearate; glycerin monostearate, glycerin distearate, pentaerythritol monostearate Rate, pentaerythritol distearate, pentaerythritol triste Polyhydric alcohol fatty acid esters rate, and the like.

  Examples of the filler include silica, diatomaceous earth, alumina, titanium oxide, magnesium oxide, pumice powder, pumice balloon, aluminum hydroxide, magnesium hydroxide, basic magnesium carbonate, dolomite, calcium sulfate, potassium titanate, and sulfuric acid. Examples include barium, calcium sulfite, talc, clay, mica, asbestos, calcium silicate, montmorillonite, pentonite, graphite, aluminum powder, molybdenum sulfide, and the like.

Examples of the coloring agent include inorganic coloring agents such as titanium oxide and calcium carbonate, and organic coloring agents such as phthalocyanine.
Examples of the lubricant include oleic acid amide, erucic acid amide, stearic acid amide and the like.

<6. Non-woven fabric>
The nonwoven fabric of the present invention forms an integrated layer of fibers called fleece from the above-mentioned metal ion-containing cellulosic fibers, general cellulosic fibers, synthetic fibers, and other materials contained as necessary. It can be manufactured by binding and performing processing such as dyeing, laminating, and coating as necessary.

The method for forming the fleece is not particularly limited, and a known method can be used. Examples are dry processes in which dried fibers are formed in a fixed or random arrangement by means of a machine called a card or an air flow called an air lay; the fibers are dispersed in water and laid on a net like a paper. And a spunbond method in which a melted raw resin is directly eluted and spun from the tip of a nozzle to form a fleece with continuous long fibers.
In particular, it is preferable to use a wet method because the cellulosic fibers are hydrophilic. In the case of the wet method, it can be produced using a conventional papermaking method. As the paper machine, various conventionally known ones, for example, a round paper machine, an inclined short net paper machine, a fourdrinier paper machine, a short net paper machine, and the like can be used. Can be combined. Examples of the drying step in the papermaking method include a Yankee dryer method, a multi-cylinder method, a hot air method, and an infrared heating method.

  The method for bonding the fibers is not particularly limited, and a known method can be used. For example, a chemical bond method of impregnating an emulsion-based adhesive resin or adhering to a fleece by a method such as spraying, heating and drying to bond the intersections of the fibers; a fleece mixed with a heat-fused fiber having a low melting point; Thermal bonding method in which fibers are adhered to each other by thermocompression bonding or hot air passing between hot rolls; a fleece is repeatedly pierced with a needle (needle) that moves up and down at a high speed, and a barb is formed on the needle. Needle punch method for entanglement of fibers; water entanglement method for entanglement of fibers by injecting a high-pressure water stream into a fleece in a columnar shape; In particular, the chemical bond method is preferred.

  The nonwoven fabric in the present invention may have a single-layer structure or a multilayer structure. In the case of a multilayer structure, it is necessary that at least one or more layers include the cellulosic fiber supporting the metal ions. When the total number of the layers is three or more, it is preferable that the outermost layer contains the cellulosic fiber supporting the metal ion because the deodorizing and antibacterial effects are more easily exhibited.

  The basis weight (basis weight) of the nonwoven fabric is preferably in the range of 10 to 100 g / m2, and more preferably in the range of 20 to 80 g / m2. When the nonwoven fabric has a multilayer structure, the basis weight of each layer is preferably 10 g / m2 or more from the viewpoint of producing a sheet that is uniform and has minimum strength in handling during production. Incidentally, the basis weight of the nonwoven fabric in the present invention means that a nonwoven fabric having an area of 0.05 m 2 or more is dried at 105 ° C. to a constant mass, and then left in a constant temperature room at 20 ° C. and 65% RH for 16 hours or more to reduce the mass. It means the mass (g) per m2 of the measured nonwoven fabric.

  The thickness of the nonwoven fabric is preferably in the range of 20 to 500 µm, more preferably in the range of 30 to 100 µm. When the nonwoven fabric has a multilayer structure, the thickness of each layer is preferably 20 μm or more from the viewpoint of producing a uniform sheet. The density of the nonwoven fabric is not particularly limited.

  The nonwoven fabric of the present invention may be used as it is, or may be laminated with a base material such as another nonwoven fabric, if necessary, and / or subjected to various processes such as embossing and pleating, followed by filtration of gas or liquid. It can be suitably used for various applications such as a filter for use. Other applications include sanitary products such as diapers, sanitary products, wipers, masks, etc., filters for filtering gas or liquid, building materials and civil engineering applications such as roofing materials (roofing materials), automotive interior materials, and clothing.

  Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

<Example 1>
[Manufacture of oxidized cellulose fiber]
5.00 g (bright dry) of bleached unbeaten kraft pulp (85% whiteness) derived from softwood was 39 mg (1 g of absolute dry) of TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl; Sigma Aldrich). Was added to 500 ml of an aqueous solution in which 514 mg of sodium bromide (1.0 mmol per 1 g of absolutely dried cellulose) was dissolved, and the mixture was stirred until the pulp was uniformly dispersed.
An aqueous sodium hypochlorite solution was added to the reaction system so that sodium hypochlorite became 5.5 mmol / g, and an oxidation reaction was started at room temperature. During the reaction, the pH in the system decreased, but the pH was adjusted to 10 by sequentially adding a 3M aqueous sodium hydroxide solution. The reaction was terminated when sodium hypochlorite was consumed and the pH in the system stopped changing.
The mixture after the reaction was filtered through a glass filter, and then washed twice with a sufficient amount of water and filtered twice to obtain oxidized cellulose fibers impregnated with water and having a solid content of 10% by mass. The pulp yield at this time was 90%, the time required for the oxidation reaction was 90 minutes, and the amount of carboxyl groups was 1.68 mmol / g.

[Support of metal ions on oxidized cellulose fiber]
Water is added to the oxidized cellulose fiber to form a dispersion having a solid content of 2%, and the pH is adjusted to 9.0. Then, the concentration of CuCl2 (manufactured by Wako Pure Chemical Industries, Ltd.) is adjusted to 1 g of the oxidized cellulose fiber. The mixture was added with stirring so as to have a concentration of 1.0 mmol / g, and the mixture was further stirred for 30 minutes, so that the oxidized cellulose fibers contained Cu ions.
On the other hand, by repeating water washing and filtration twice with a sufficient amount of water, unreacted metal salts are removed, and a water-impregnated Cu ion-carrying cellulose fiber having a solid content of 30% by mass (containing metal ions) Cellulosic fiber) was obtained.
The content of metal ions with respect to the oxidized cellulose fibers was 31.9 mg / g, and the freeness of the metal ion-containing cellulose fibers was 500 ml.

[Manufacture of nonwoven fabric]
Pulp (NBKP having a freeness of 600 ml; Nippon Paper Industries Co., Ltd.) as the above-mentioned metal ion-containing cellulosic fiber, cellulosic fiber containing no metal ion (general cellulosic fiber), polyester fiber (product name: Tepilus TT04N) as synthetic fiber A cut length of 5 mm, manufactured by Teijin Limited, and a wet strength agent (product name: WS4020, manufactured by Seiko PMC Co., Ltd.) were mixed at the mixing ratio shown in Table 1, and water was further added to add a solid content concentration of 0.5% by mass. Was prepared. In Table 1, the mixing ratio of each fiber and the wet strength agent is a value based on the total amount of all the fibers.
This was paper-made with a round hand-making machine, dehydrated with a press machine, and dried at 85 ° C. with a cylinder dryer to produce a round non-woven fabric having a diameter of about 16 cm.

<Example 2>
A method similar to that of Example 1 except that the aqueous solution of CuCl2 was changed to an aqueous solution of AgNO3 (concentration per gram of oxidized cellulose-based fiber: 1.0 mmol / g) in the step of supporting metal ions on the oxidized cellulose-based fiber. To prepare a nonwoven fabric.
The content of Ag ions with respect to the oxidized cellulose fibers was 20.0 mg / g, and the freeness of the metal ion-containing cellulose fibers was 500 ml.

<Example 3>
In the step of manufacturing the nonwoven fabric, the mixing ratio of the metal ion-containing cellulosic fiber to the total fiber content was changed from 20% by mass to 50% by mass, and the mixing ratio of the metal ion-free cellulosic fiber to the total fiber content was 50%. A nonwoven fabric was produced in the same manner as in Example 1, except that the mass% was changed to 20 mass%.

<Comparative Example 1>
In the process of manufacturing the nonwoven fabric, except that the metal ion-containing cellulosic fiber was not blended and the same amount of metal ion-free cellulosic fiber (NBKP pulp with a freeness of 600 ml, manufactured by Nippon Paper Industries) was used. A nonwoven fabric was produced in the same manner as in Example 1.

<Comparative Example 2>
In the step of manufacturing the nonwoven fabric, except that a commercially available metal (Cu) ion-supported zeolite high-density crystallized pulp (trade name: Copper Cellgaia, manufactured by Rengo Co., Ltd.) was used instead of the metal ion-containing cellulosic fiber, A nonwoven fabric was produced in the same manner as in Example 1.

<Comparative Example 3>
A nonwoven fabric was produced in the same manner as in Example 1, except that the treatment for supporting metal ions on the oxidized cellulose fiber was not performed and the oxidized cellulose fiber was contained in the nonwoven fabric as it was.

<Reference example>
The obtained sheet of nonwoven fabric is impregnated with a reducing agent solution of 200 ppm, a filter paper is overlaid to remove an excess aqueous solution, and dried for 15 minutes by a blow dryer at 50 ° C., whereby the sheet is contained in the metal ion-containing cellulosic fiber. A nonwoven fabric was produced in the same manner as in Example 1, except that Cu ions were reduced to Cu nanoparticles.

<Evaluation>
A test piece was prepared from the obtained non-woven fabric, and the test piece was subjected to the following methods for deodorization, antibacterial properties, tensile strength and elongation as mechanical properties, lint as an index of fine powder detachment, and a filter. The air permeability and the particle collection rate were evaluated as performance.

[Deodorant]
A gas bag with a cock containing four test pieces of 5 cm × 5 cm was filled with 1.5 L of ammonia gas having a humidity of 50% and adjusted to 300 ppm by an air pump. Next, the suction tube and the rubber tube were connected to the detection tube, and the rubber tube was connected to the gas bag. Then, the concentration of ammonia gas in the gas bag was measured 50 minutes after the air was filled.
：: Very good Residual concentration is 1/5 or less of initial value ○: Good Residual concentration is 1/4 or less of initial value △: Normal Residual concentration is higher than 1/4 of initial value and 1/3 or less ×: Poor Residual concentration is initial value In addition, the same test was performed in the case where ammonia gas adjusted to 500 ppm and humidity of 90% was used, and in a state where 0.5 ml of water was dropped on the test piece (when wet). Was evaluated.
If the evaluation is ◎, the deodorizing property is excellent.

[Antibacterial]
A qualitative test was performed by the halo method according to JIS L1902 “Testing method and antibacterial effect of textile products”. Specifically, an agar medium containing Escherichia coli was prepared, a 5 cm x 5 cm test piece was placed thereon, and after culturing at 37 ° C for 17 hours, the “growth inhibition zone” of the test bacteria formed around the sample was formed. The presence or absence was checked. Evaluation was made according to the following criteria.
：: A growth inhibition zone was observed, indicating antibacterial properties.
×: No growth inhibition zone was observed, and no antibacterial property was observed.

[Specific tensile strength]
In accordance with JIS L1913 "General nonwoven fabric test method", a test piece having a width of 25 mm and a length of 300 mm was gripped with a constant speed elongation type tensile tester (manufactured by Kumagaya Riki Kogyo Co., Ltd.) at a gripping interval of 200 mm and a pulling speed of 10 mm / min. , A load was applied until the test piece was cut, the strength at the maximum load was defined as the tensile strength, and the measurement result was divided by the grammage to obtain the specific tensile strength.

[Lint]
A dust test was performed according to JIS B9923 (tumbling method), and the measurement was performed using a particle counter (manufactured by Rion, product name “KC-01D1”). Evaluation was made according to the following criteria. The better the evaluation, the less the fine powder such as paper powder and zeolite falls. If the evaluation is ○, there is no practical problem.
○: Normal ×: Poor

[Ventilation]
According to JIS L1913 "General nonwoven fabric test method", it measured by the Gurley type method. Specifically, using a Gurley-type air permeability tester (manufactured by Toyo Seiki Seisaku-Sho, Ltd.), for a test piece of 50 mm × 130 mm, 10 pieces of the test pieces were stacked and inserted into the air jet port and tightened. The time (in seconds) required for 200 mL of air to be blown through the specimen under the load caused by the mass was measured.

[Particle collection rate]
In accordance with JIS B9908 "Performance test method for air filter unit for ventilation and electric dust collector for ventilation", test method type 3 was implemented. Specifically, eleven kinds of test powder 1 (Kanto loam, 50% median diameter 2 μm) specified in JIS Z 8901 were used as dust, and the collection efficiency was calculated by the following equation.
Particle collection rate (%) = (1-C2 / C1) × 100
C1: The number of dust particles on the upstream side of the filter C2: The number of dust particles on the downstream side of the filter Regarding the calculated results, 場合 was given when the result was equal to or more than Comparative Example 1 described below, and × was given when the result was inferior. If the evaluation is ○, there is no practical problem.

As is clear from Table 2, in each of the examples containing the metal ion-containing cellulosic fiber and the synthetic fiber, the mechanical properties (specific tensile strength) were good, and the deodorant / antibacterial effect was irrespective of the humidity. It was very high at times.
On the other hand, Comparative Example 1, which did not contain the metal ion-containing cellulosic fiber, was inferior in deodorant properties and mechanical properties.
In Comparative Example 2 containing a commercially available high density crystallized pulp supporting metal (Cu) ions instead of the metal ion-containing cellulosic fibers, the deodorizing properties were inferior to those of the examples, especially under high humidity and wet conditions. Was inferior in deodorizing property and powder fell off.
In the case of Comparative Example 3 in which the oxidized cellulose fiber did not carry metal ions, the deodorizing property was poor.

Claims (3)

Contains one or more metal ions selected from the group consisting of Ag, Au, Pt, Pd, Ni, Mn, Fe, Ti, Al, Zn, and Cu with respect to a cellulosic fiber having a carboxyl group or a carboxylate group on the surface. A metal ion-containing cellulosic fiber, and a non-woven fabric containing a synthetic fiber ,
A nonwoven fabric further comprising a cellulosic fiber containing no metal ions.   The nonwoven fabric according to claim 1, wherein in the metal ion-containing cellulosic fiber, a part of the hydroxyl group at the C6 position in the glucose unit of cellulose is oxidized to a carboxyl group.   The nonwoven fabric according to claim 1, wherein the metal ion is an Ag ion or a Cu ion.