JP2003201668A - Photocatalytic cellulose fiber and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photocatalytic cellulose fiber produced by supporting a photocatalyst composed of titanium oxide fine particles on a cellulose fiber substrate and exhibiting suppressed oxidative decomposition of the cellulose fiber caused by the titanium oxide photocatalyst. <P>SOLUTION: A slurry containing a siliceous raw material, a calcareous raw material, water and 10-125 pts.wt. (solid basis) of a cellulose fiber based on 100 pts.wt. (solid basis) of the sum of the siliceous raw material and the calcareous raw material is subjected to hydrothermal reaction to obtain a cellulose fiber substrate coated with hydrated calcium silicate and having the primary particle of the hydrated calcium silicate crystallized on the surface of each cellulose fiber constituting the cellulose fiber substrate. A photocatalyst composed of fine particles of titanium oxide is supported on the surface of the cellulose fiber substrate coated with the hydrated calcium silicate to obtain the photocatalytic cellulose fiber. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a photocatalytic property having an environmental purifying function such as deodorant, antibacterial, antifouling, water purification and decomposition of harmful substances, which is obtained by supporting a titanium oxide photocatalyst on a cellulose fiber support. Regarding the cellulose fiber, more specifically, in order to suppress the oxidative decomposition deterioration of the cellulose fiber support due to the titanium oxide photocatalyst, calcium silicate water is provided between the cellulose fiber support and the titanium oxide photocatalyst layer of the fine particles carried on the support. The present invention relates to a photocatalytic cellulose fiber having a structure in which a protective layer made of a Japanese product is formed, and a method for producing the same.

[0002]

As is well known, since titanium oxide photocatalyst has a very strong oxidizing power, it can easily decompose harmful chemical substances and malodorous substances in water and air to render them harmless. Since it also has antibacterial and antifungal properties, it has attracted attention as a functional material capable of imparting a new environmental purification function to cellulose fibers and the like.

The basic concept of titanium oxide photocatalyst and its application to various fields are described in "Light Clean Revolution-Titanium oxide photocatalyst plays an active role (Akira Fujishima, Kazuhito Hashimoto, Toshiya Watabe,
"CMC Co., Ltd., issued in January 1997)" and "Introduction to Visual Science: How Photocatalyst Works (Akira Fujishima, Kazuhito Hashimoto, Toshiya Watanabe, Nihon Jitsugyo Publishing Co., Ltd., 20
Published in October 2000), the photocatalytic function of titanium oxide is deodorized in everyday familiar environmental spaces.
Volatile organic compounds (VOCs) such as adhesives that are used for antibacterial and mildewproof purposes, and are used by a variety of people from general houses to hotels, public facilities, hospitals, nursing homes, etc. Application to a wide variety of environmental cleanups such as the decomposition of is proposed.

In the case of utilizing the photocatalytic function of titanium oxide as described above, since the photocatalytic reaction is a reaction on the particle surface, a highly active titanium oxide photocatalyst having a small particle diameter and a large specific surface area is effective. If the fine particle powder is used as it is, problems and drawbacks occur in handling and recovery, and in order to put it into practical use, it is indispensable to support the fine particle titanium oxide photocatalyst on the support.

However, since the fine-particle titanium oxide photocatalyst has a strong oxidizing power, when the support to be supported is an organic substance, the support is also decomposed. There are various restrictions in supporting fine particles of titanium oxide photocatalyst on the material.

Therefore, as a technical means for supporting a titanium oxide photocatalyst on an organic fiber support such as cellulose fiber, for example, Japanese Patent Laid-Open No. 8-173805 discloses that a water-soluble inorganic substance is allowed to act on a support made of pulp fiber. After
A technique is disclosed in which this is insolubilized to cause titanium oxide to coagulate and deposit on the surface of the water-insolubilized inorganic material to firmly hold it on the support.

Further, in Japanese Patent Laid-Open No. 9-59892,
Ultrafine titanium oxide with an X-ray particle size of 100 nm or less or modified ultrafine titanium oxide whose surface is modified with zinc oxide, etc., and an inorganic material selected from sepiolite, silica gel, bentonite, magnesium sulfate, asbestos and activated carbon supporting them. A technique is disclosed in which a filler and an organic fibrous material having a paper-making ability such as pulp are made into paper to produce a titanium oxide-containing paper.

Further, in Japanese Patent Laid-Open No. 2000-110098, oxidation produced by drying an aqueous dispersion containing silica sol or alumina sol in a mixing ratio of 5: 1 to 1: 5 with respect to titanium oxide fine powder. A technique of internally adding titanium composite particles to an organic support such as paper is disclosed.

[0009]

As seen in the above-mentioned publications, the surface of the organic fiber support is protected in advance with an inorganic substance, instead of directly supporting the fine particle titanium oxide having a high photocatalytic decomposition ability on the organic fiber support. By doing so, deterioration of the cellulose fiber support can be prevented or suppressed.

However, it is difficult to fix the inorganic substance to the support with sufficient strength by the technique of supporting the titanium oxide photocatalyst on the organic fiber support disclosed in the above-mentioned respective publications, and the titanium oxide photocatalyst is applied to cellulose. A possible problem is that it is necessary to add a considerable amount of an inorganic substance in order to prevent it from coming into contact with the fiber support.

Furthermore, the methods disclosed in the above-mentioned publications do not preliminarily support the titanium oxide photocatalyst by protecting the surface of each fiber constituting the cellulose fiber support with an inorganic substance in advance. . In other words, since each fiber constituting the cellulose fiber support is not protected by one unit, there is a possibility that there is a high possibility that the application in practical use is limited or restricted.

In view of these problems, the present invention protects the surface of each fiber constituting a cellulose fiber support by an inorganic substance to prevent or suppress the deterioration of the cellulose fiber support. The technical challenge is to provide materials that can be used for various purposes and have a new environmental purification function, not just paper materials.

[0013]

In order to achieve the above-mentioned object, in protecting the surface of each fiber constituting a cellulosic fiber support with an inorganic substance, the present inventor has filed a patent application. 2000-100101
It has been found that a natural cellulose material, in which primary particles of calcium silicate hydrate are crystallized in the form of twigs, can be used on the surface of the fiber as proposed in Japanese Patent Application Laid-Open No. 001-240458). In addition, the present inventor relates to the natural cellulose material concerned.
"Hydrothermal synthesis and papermaking properties of zonotolite-coated pulp fiber" (Keiji Takahashi et al., 33rd Autumn Meeting of the Chemical Engineering Society of Japan, B-205 (2000)) and "Xono
lite Coatingon to Pulp F
iberSurface underunder Hydroth
"Ermal Conditions" (K. Takah
ashi, at. al. , Fxend Abstra
ct and Proceedings of Jo
int 6 ^th International Sym
possumonHydrothermalReac
tions & 4 ^th International
Conference on Solvo-Ther
mal Reactions, 100 (July25-
28, 2000, Kochi, Japan).

The present invention has been completed based on the above findings, and the problems can be achieved by the present invention as follows.

That is, the photocatalytic cellulose fiber according to the present invention is a photocatalytic cellulose fiber in which a titanium oxide photocatalyst of fine particles is carried on a cellulose fiber support, and the surface of each cellulose fiber constituting the cellulose fiber support and the above An inorganic protective layer made of calcium silicate hydrate is formed between the fine particle titanium oxide photocatalyst and the titanium oxide photocatalyst in order to suppress oxidative degradation by the titanium oxide photocatalyst.

The method for producing a photocatalytic cellulose fiber according to the present invention comprises a siliceous raw material, a calcareous raw material, water, and
Solid content 10 in a mixture of the siliceous raw material and the calcareous raw material
A raw material slurry containing a cellulose fiber raw material having a solid content of 10 to 125 parts by weight with respect to 0 part by weight is subjected to a hydrothermal treatment reaction to give calcium silicate water as an inorganic protective layer on the surface of each cellulose fiber constituting the cellulose fiber support. After obtaining a calcium silicate hydrate-coated cellulose fiber support having a structure in which the primary particles of the hydrate are crystallized, a particulate titanium oxide photocatalyst is supported on the surface of the calcium silicate hydrate-coated cellulose fiber support. It is characterized by that.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

Embodiment 1.

The photocatalytic cellulose fiber and the method for producing the same in the present embodiment will be described. First, in the mixture of siliceous raw material, calcareous raw material and water, the solid content of the mixture of siliceous raw material and calcareous raw material is 100%. A raw material slurry is obtained by adding a cellulose fiber raw material having a solid content of 10 to 125 parts by weight to parts by weight and uniformly stirring and mixing under conditions such as normal temperature and normal pressure, warm normal pressure or warm press. Alternatively, a raw material slurry containing an intermediate product of CSH in the stirring and mixing process is obtained, and subsequently, the raw material slurry is subjected to a hydrothermal treatment reaction by using an autoclave to form a unit of each fiber constituting the cellulose fiber support. Calcium silicate hydrate-coated cellulosic structure with primary particles of calcium silicate hydrate crystallized on its surface as an inorganic protective layer After preparing the fiber support, the fine particle titanium oxide photocatalyst is supported on the surface of the calcium silicate hydrate-coated cellulose fiber support, and then the screening, washing and drying steps are performed to obtain the desired photocatalyst. Producing permeable cellulose fibers.

As described above, in the manufacturing process of the photocatalytic cellulose fiber in the present embodiment, the surface of each fiber constituting the cellulose fiber support is prevented in order to prevent and suppress the oxidative degradation by the titanium oxide photocatalyst. It can be roughly classified into a step of preparing a calcium silicate hydrate-coated cellulose fiber having an inorganic protective layer made of calcium silicate hydrate and a step of supporting a particulate titanium oxide photocatalyst on the fiber support.

As the siliceous raw material, silica stone, silica sand or the like may be used if it is crystalline, and diatomaceous earth, white carbon, silica fume or the like may be used if it is amorphous.

As the calcareous raw material, powdered slaked lime obtained by dry digestion of quick lime or slurry slaked lime (lime milk) obtained by wet digestion of quick lime with a large amount of water may be used.

As an example of the cellulose fiber, wood pulp can be mentioned. Wood pulp is advantageous in terms of quality and cost, and NBKP (softwood bleached kraft pulp) and LBKP (hardwood bleached kraft pulp) are preferable.

These cellulose fibers are used by being dispersed or disaggregated in an aqueous solution by using a stirrer, a juicer, or the like, or the fibers are mechanically beaten by a refiner, beater or the like to be swelled by rubbing to fibrillize the fibers. It may be used after it is caused to initiate a hydrogen bond.
By subjecting the surface of the fiber to fibrillation by the treatment, it becomes advantageous for supporting the inorganic material on the surface of the cellulose fiber support.

The mixing method of each raw material is not particularly limited, but the raw material slurry in which the respective raw materials are uniformly mixed is obtained by stirring and mixing under conditions such as normal temperature and normal pressure, warm and normal pressure, and warm and pressurization. . In addition, this stirring and mixing process reaction is promoted, and CSH
It may be a raw material slurry containing the intermediate product.

The calcium silicate hydrate is a crystalline calcium silicate hydrate generally called xonotlite or tobermorite, which is obtained by subjecting a siliceous raw material, a calcareous raw material and water to a hydrothermal treatment reaction in an autoclave. The mixing ratio of the siliceous raw material and the calcareous raw material, which is a synthesis condition for synthesizing calcium hydrate (CaO
/ SiO ₂ molar ratio) is 0.85 for zonotolite
~ 1.20 range, 0.60 for tobermorite
A range of 0.95 is preferred. Further, with respect to 100 parts by weight of a solid mixture of a siliceous raw material and a calcareous raw material, the cellulose fiber raw material has a solid content of 10 to 125 parts by weight, and in view of dispersibility in an aqueous raw material slurry, the solid content is preferably 2
It is preferable to add 5 to 75 parts by weight. The water / solid content (silicic material raw material + calcareous raw material + cellulose fiber raw material) ratio is in the range of 50 to 250, preferably 100 to 20.
A range of 0 is good.

For this reason, although the reason is not clear, in the process of forming calcium silicate hydrate by the autoclave hydrothermal treatment reaction, primary particles of calcium silicate hydrate crystallize on the surface of each fiber constituting the cellulose fiber support. As the cellulose fibers and calcium silicate hydrate are integrated (the crystallized state can be confirmed by an electron microscope), each fiber is coated with calcium silicate hydrate.

The hydrothermal treatment reaction is preferably carried out using a stirring autoclave at a reaction temperature of 150 to 230 ° C. for 1 to 12 hours, more preferably 2 to 8 hours in industrial production.

After the hydrothermal treatment reaction, the fiber product is sieved from the water-dispersible slurry state with a sieve and the calcium silicate hydrate not adhered to the fibers is washed away by washing. A raw material for supporting a fine particle titanium oxide photocatalyst. Note that sieving and washing may not be performed at this stage, and sieving and washing may be performed after the treatment for supporting the titanium oxide photocatalyst is completed.

The fine particle titanium oxide photocatalyst used has an average particle size of 5 to 150 nm and can be used in any type such as amorphous, rutile type and anatase type. Anatase type titanium oxide photocatalyst has photocatalytic activity. It is good because it is excellent in terms of. Further, those in the form of a slurry, a sol solution, a gel, a sol / gel mixture and the like having stable sedimentation and dispersibility are particularly preferable. For example, as a commercially available product, a product name “Photocatalyst sol A” manufactured by Photocatalysis Laboratory
"T series" and the like.

When amorphous titanium oxide is used, it does not crystallize in anatase titanium oxide in an amorphous state at room temperature, but it contains uniform fine particles and has excellent adhesiveness and sticking and carrying ability. Since it is high, there is no problem even if amorphous titanium oxide is first fixed and then hydrothermal heat treatment at about 120 to 200 ° C. is again performed by an autoclave to crystallize the amorphous type into the anatase type.

As a method for supporting the titanium oxide photocatalyst on the calcium silicate hydrate-coated cellulose fiber support, a water-soluble slurry in which the cellulose fiber is dispersed is added to a slurry, a sol solution, or a gel having stable sedimentation and dispersibility. The calcium silicate hydrate-coated cellulose fiber can be fixed by a simple treatment such as adding a fine particle titanium oxide photocatalyst in the form of a sol / gel mixture and stirring and mixing.

As a method for supporting fine particles of titanium oxide photocatalyst on the calcium silicate hydrate-coated cellulose fiber support, for example, a known dipping method or spraying spray method is used after a sheet or the like is prepared using the fiber. Coated on a cellulose fiber support by a coating method such as
After that, a method of natural drying or heating and drying using a dryer can be applied.

[0034]

EXAMPLES The present invention will be described with reference to Examples and Comparative Examples. However, the present invention is not limited to the following examples.

Example 1: Finely pulverized silica stone powder (SiO ₂ : 97.8%) as a siliceous raw material and slaked lime powder (CaO: 72.6%) as a lime raw material, a CaO / SiO ₂ molar ratio of 1.05. To 100 parts by weight of the raw material powder blended in
NBKP (softwood bleached kraft pulp) fiber solids 30
A part by weight of water was added, and then 100 parts by weight of the solid content of the finely ground silica stone powder, slaked lime powder, and NBKP fibers was added to water to prepare 77 times by weight water to prepare a raw material slurry. Subsequently, this raw material slurry was heated in a stirring autoclave at a stirring number of 200 rpm to a temperature of 200 ° C. in 2 hours, and after being held for 8 hours, was heated to 90 °
The hydrothermal treatment reaction was performed under the condition that the temperature was lowered to 0 ° C in 1 hour. As the NBKP fiber, swelling pulp disaggregated in water using a juicer mixer was used.

Next, the synthesized product slurry was added to 60 mes
After sieving with a standard sieve of h (mesh opening 250 μm), only the fiber component in the product was taken out and subjected to a water washing treatment for 10 minutes to thoroughly wash away the calcium silicate hydrate not adhered to the fiber.

After washing with water, a small amount of fiber was sampled and dried at a temperature of 110 ° C. for 12 hours. The fiber surface of the dried sample is a field emission scanning electron microscope (Hitachi S
-4700 type), the NBKP fiber surface was observed to have the following characteristics as seen in the electron micrographs of FIGS. 1 and 2.
It was possible to obtain calcium silicate hydrate-coated NBKP fibers in which fine acicular primary particles of calcium silicate hydrate were crystallized on the surface of each fiber.

The calcium silicate hydrate-coated NB
An X-ray analyzer (RINT-made by Rigaku-
2000 series), it was confirmed that it was a peak peculiar to the NBKP fiber and a peak peculiar to zonotolite as seen in the X-ray diffraction peak of FIG. This is NBKP used as the raw material shown in FIG.
X-ray diffraction peak of fiber and X of zonotolite shown in FIG.
It can be confirmed by coincidence with the line diffraction peak.

Although it is not clear about this production process, a zonotolite precursor in the early stage of the reaction, that is, a substance that becomes a crystal nucleus is fixed to the surface portion of the NBKP fiber having high irregularity, and as the reaction proceeds, zonotolite is formed on the surface of the NBKP fiber. It is considered that the crystals crystallize and grow to firmly adhere to the NBKP fibers through chemical bonds such as hydrogen bonds.

The calcium silicate hydrate-coated NB
KP fiber ash content test method for papermaking pulp JIS-P-8
According to the method according to 204, it was ignited at 800 ° C. for 2 hours in an electric furnace to be sufficiently ashed, allowed to cool to room temperature in a desiccator, and then weighed. In addition, this operation was repeated until the weight became constant, and the amount of the inorganic substances supported on the NBKP fiber was measured. Ash content A (%) is A = (W / S) x 100
(S: absolute dry weight of sample (g) W: ash weight (g)). As a result, the amount of inorganic substances carried on the NBKP fibers, that is, the ash content A (the amount of calcium silicate hydrate) was 26.7%.

Next, 100 parts by weight of the calcium silicate hydrate-coated NBKP fiber thus obtained is added with water so that the amount of water becomes 500 parts by weight, and the calcium silicate hydrate-coated NBK is added.
A P fiber dispersion solution was prepared. 300 rp of this dispersion solution
titanium oxide photocatalyst sol (manufactured by Photocatalyst Laboratory Co., Ltd .; AT-01: TiO ₂ content 3.48 wt.
%), NBKP fiber 100 coated with hydrated calcium silicate
₂ parts by weight of titanium oxide (TiO ₂ ) solid content with respect to parts by weight
0 part by weight was added, and the mixture was stirred and mixed at a temperature of 80 ° C. for 4 hours.

After completion of the stirring and mixing treatment of the titanium oxide photocatalyst sol, the treatment liquid is treated with a standard mesh of 60 mesh (opening 250).
(μm) to remove only the fiber content in the product,
The titanium oxide photocatalyst not adhered to the fibers was sufficiently washed off by performing a water washing treatment for 10 minutes.

After washing with water, a small amount of fiber was sampled and dried at a temperature of 110 ° C. for 12 hours. The fiber surface of the dried sample is a field emission scanning electron microscope (Hitachi S
-4700 type), fine acicular primary particles of calcium silicate hydrate were found on the surface of the NBKP fiber coated with hydrated calcium silicate, as shown in the electron micrographs of FIGS. 6 and 7. Calcium silicate hydrate coated NBKP fibers crystallized on the surface can be observed, but TiO ₂
No particles could be observed.

Next, as a result of measurement by an X-ray analyzer, an X-ray diffraction peak of titanium oxide (anatase type) was confirmed at around 25 ° as seen in the X-ray diffraction peak of FIG. This is compared with the X-ray diffraction result of the known anatase type titanium dioxide (manufactured by Wako Pure Chemical Industries, Ltd .: Wako first-class reagent) shown in FIG. 9, and when the peaks match, titanium oxide is present in the fiber. I found out that This peak corresponds to the calcium silicate hydrate coating N in FIG.
Since it was not found in BKP fiber, calcium silicate hydrate coated NB obtained by stirring and mixing titanium oxide photocatalyst sol
It was confirmed that titanium oxide (anatase type) was fixed to the KP fiber.

Ash content B (%) was determined in the same manner as described above. As a result, the amount of the inorganic substances supported on the fibers, that is, the ash content B (the total of the amount of calcium silicate hydrate and the amount of titanium oxide) was 36.1%.

Furthermore, calcium silicate hydrate-coated NBKP
Energy dispersive X-ray analysis system (HORI) for the surface of NBKP fiber supporting titanium oxide coated with calcium silicate hydrate on which the fiber and titanium oxide photocatalyst are fixed and supported.
Qualitative analysis of titanium was carried out by BA EMAX-7000). The qualitative analysis results are shown in FIGS. 10 and 11. As shown in FIG. 10, Si and Ca were mainly detected and Ti was not detected from the observed portion of the surface of the calcium silicate hydrate-coated NBKP fiber which was not subjected to the supporting treatment of the titanium oxide photocatalyst. In addition, the calcium silicate hydrate coating N subjected to the supporting treatment of the titanium oxide photocatalyst shown in FIG.
From the observed portion of the surface of the BKP fiber, mainly Si, C
a and Ti were detected.

From these results, the titanium oxide photocatalyst sol was stirred and mixed in the calcium silicate hydrate-coated NBKP fiber dispersion solution by a simple treatment method, and the titanium oxide photocatalyst sol was subjected to sufficient washing treatment, Calcium silicate hydrate coating N without all photocatalyst being detached / peeled off
It was confirmed that the BKP fibers were fixed.

Comparative Example 1: Finely pulverized silica stone powder (SiO ₂ : 97.8%) as a siliceous raw material and slaked lime powder (CaO: 72.6%) as a lime raw material were mixed in a CaO / SiO ₂ molar ratio of 105. 10 to 100 parts by weight of raw material powder
A raw material slurry was prepared by adding water so that the weight of the water became 0 times by weight. Then, this raw material slurry was stirred at a stirring speed of 200 rpm in a stirring autoclave at a temperature of 200
The temperature was raised to 2 ° C. in 2 hours, the temperature was maintained for 8 hours, and then the hydrothermal treatment reaction was performed under the condition that the temperature was lowered to 90 ° C. in 1 hour. After the reaction was completed, 30 parts by weight of NBKP fiber solid content was added to the produced slurry, and a hydrothermal treatment reaction was carried out by the same method.

As in Example 1, only the fiber component in the product was taken out, a small amount of fiber was sampled, and the temperature was adjusted to 110.
It was dried at ° C for 12 hours. When the fiber surface of the sample was observed with a field emission scanning electron microscope, NBKP
It was not confirmed that fine acicular primary particles of calcium silicate hydrate were crystallized on the fiber surface.

Further, when the fiber was measured by an X-ray analyzer, a peculiar peak of NBKP fiber could be confirmed.
No peculiar peak of xonotlite could be confirmed.

Similarly, the ash content C (%) was determined, and the amount of the inorganic substances carried on the fiber, that is, the ash content C (the amount of calcium silicate hydrate) was 1.36%.

Further, the titanium oxide photocatalyst sol and the stirring and mixing treatment were carried out in the same manner as in Example 1 except that the fibers prepared in Comparative Example 1 were used in place of the calcium silicate hydrate-coated NBKP fibers in Example 1. went.

As in Example 1, only the fiber content in the product was taken out, a small amount of fiber was sampled, and the temperature was adjusted to 110.
It was dried at ° C for 12 hours. The surface of the fiber of the sample was observed by a field emission scanning electron microscope, but it was not confirmed that TiO ₂ particles were observed, and the X-ray diffraction peak of titanium oxide (anatase type) could not be confirmed by an X-ray analyzer. . The ash content D (%) was also determined in the same manner as described above, but the amount of the inorganic substances supported on the fiber, that is, the ash content D (the total amount of calcium silicate hydrate and the amount of titanium oxide) was 2.41%.
And a small amount. Furthermore, the surface of the fiber was qualitatively analyzed for titanium by an energy dispersive X-ray analysis system.
Si, Ca and Ti were hardly detected.

From these results, NBKP fibers not coated with calcium silicate hydrate were subjected to sufficient washing treatment by a simple treatment method such as stirring and mixing the titanium oxide photocatalyst sol in the fiber dispersion solution. In some cases, it was confirmed that it was difficult to support the titanium oxide photocatalyst on the fiber.

Preparation of sheet sample for acetaldehyde decomposition test

Example 2 Calcium silicate hydrate-coated NBKP fibers carrying the titanium oxide photocatalyst obtained in Example 1 were used as a papermaking raw material to make paper using a 25 cm square sheet machine, and the basis weight was 44.6 g / to obtain a titanium oxide photocatalyst carrying calcium silicate hydrate coated NBKP fiber sheet m ^2. This sheet was cut into length x width: 100 x 100 mm to obtain a test sheet sample A.

Comparative Example 2: Using the calcium silicate hydrate-coated NBKP fiber (which does not carry a titanium oxide photocatalyst) in Example 1 as a papermaking raw material and in the same manner as in Example 1, a basis weight of 41.1 g / to obtain a calcium silicate hydrate coated NBKP fiber sheet m ^2. It was cut in the same manner as in Example 2 to obtain a test sheet sample B.

Comparative Example 3: Using the NBKP fiber obtained in Comparative Example 1 as a papermaking raw material, in the same manner as in Example 1, the basis weight was 4
A 2.4 g / m ² NBKP fiber sheet was obtained. Example 2
It was cut in the same manner as above to obtain a test sheet sample C.

Acetaldehyde decomposition test

Example 3: An acetaldehyde decomposition test was carried out to evaluate the photocatalytic performance of the sheet sample A prepared in Example 2. It was put in a 1.05 liter plastic circulation container, and the inside of the container was replaced with Air of a compressor. 3.0 μL of acetaldehyde in this circulation container
After injecting and circulating the inside of the container by an Air pump for 30 minutes, the measurement was started by irradiating with ultraviolet light intensity of 1.5 mW / cm ² using 5 black lights of 15 W as light sources. The acetaldehyde in the container was sampled with a syringe every 15 minutes, and the acetaldehyde concentration was measured by gas chromatography for 60 minutes.

Comparative Examples 4 to 5: The acetaldehyde concentration was measured by the same method as described above except that the sheet sample B in Comparative Example 2 and the sheet sample C in Comparative Example 3 were used.

The results of Example 3 and Comparative Examples 4 to 5 are summarized in Table 1 and FIG.

[Table 1]

As is clear from Table 1 and FIG. 12, it was confirmed that the sample sheet A showed a decrease in the acetaldehyde concentration in the plastic circulation container, and the sample sheets B and C showed a large decrease in the acetaldehyde concentration. Since it was not confirmed, it was confirmed that the sample sheet A produced using the titanium oxide photocatalyst-supported calcium silicate hydrate-coated NBKP fiber had excellent photocatalytic decomposition ability.

【The invention's effect】

According to the present invention, siliceous raw material, slaked lime, N
A raw material slurry containing BKP fiber and water is prepared, and the raw material slurry is subjected to a hydrothermal treatment reaction in a stirring autoclave to crystallize calcium silicate hydrate on the surface of the NBKP fiber. Calcium silicate hydrate-coated NBKP fiber Was prepared, and the titanium oxide photocatalyst sol was subjected to a simple treatment method such as stirring and mixing in a calcium silicate hydrate-coated NBKP fiber dispersion solution, and even though it was sufficiently washed with water, all of the titanium oxide photocatalyst was A sheet excellent in photocatalytic activity can be provided which can be carried on calcium silicate hydrate-coated NBKP fibers without desorption or peeling.

Therefore, it can be said that the industrial applicability of the present invention is very high.

[Brief description of drawings]

FIG. 1 Calcium silicate hydrate coating N in Example 1
It is a drawing-substitute electron micrograph showing the fiber structure of BKP fibers at a magnification of 2000.

FIG. 2 Calcium silicate hydrate coating N in Example 1
It is a drawing-substitute electron micrograph showing the fiber structure of BKP fibers at a magnification of 5000.

FIG. 3 Calcium silicate hydrate coating N in Example 1
It is a diagram which shows the analysis result of the crystal structure by the X-ray-diffraction peak of BKP fiber.

FIG. 4 is a diagram showing an analysis result of a crystal structure of an NBKP fiber in Example 1 by an X-ray diffraction peak.

FIG. 5 is a diagram showing an analysis result of a crystal structure by an X-ray diffraction peak of xonotlite in Example 1.

6 is a drawing-substitute electron micrograph showing the fiber structure of calcium silicate hydrate-coated NBKP fibers supporting a titanium oxide photocatalyst in Example 1 at a magnification of 2000. FIG.

7 is a drawing-substitute electron micrograph showing a fiber structure of calcium silicate hydrate-coated NBKP fibers supporting a titanium oxide photocatalyst in Example 1 at a magnification of 5000. FIG.

FIG. 8 is a diagram showing the analysis result of the crystal structure of the calcium silicate hydrate-coated NBKP fiber supporting the titanium oxide photocatalyst in Example 1 by the X-ray diffraction peak.

FIG. 9 is a diagram showing an analysis result of anatase type titanium dioxide (manufactured by Wako Pure Chemical Industries, Ltd .: Wako first-class reagent) crystal structure in Example 1.

FIG. 10 is a diagram showing a qualitative analysis of titanium by an energy dispersive X-ray analysis system on the surface of NBKP fibers coated with calcium silicate hydrate in Example 1.

FIG. 11 is a diagram showing a qualitative analysis of titanium by an energy dispersive X-ray analysis system on the surface of NBKP fibers coated with a titanium oxide photocatalyst-supported calcium silicate hydrate in Example 1.

FIG. 12 is a diagram showing photocatalytic performance evaluation observed in each acetaldehyde decomposition test of sample sheets A, B, and C.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C01B 33/24 101 A61L 9/00 C 4L055 D21H 11/16 9/18 // A61L 9/00 D06M 101: 06 9/18 11/12 D06M 101: 06 B01D 53/36 J G F term (reference) 4C080 AA07 AA09 BB02 BB05 BB08 CC01 HH05 JJ03 KK08 LL03 LL10 MM02 NN01 NN24 QQ03 4D048 AA19 AA21 AB03 BA07X BA41X BB08 EA01 4G069 AA03 AA08 BA04A BA04B BA29A BA29B BA48A CA01 CA05 CA10 CA11 CA17 CD10 DA06 EA03X EA03Y EC22X EC22Y EE06 FA03 FB15 FB17 4G073 BA11 CC08 FB10 FB17 FC03 UA01 UA05 UB22 4L031 AA02 BA09 BA19 DA00 4L055 AA02 AC06 AG05 AG16 AG18 AG19 AH01 AH21 AH50 BB30 EA32 FA30 GA27

Claims (3)

[Claims] 1. A photocatalytic cellulose fiber in which a fine particle titanium oxide photocatalyst is supported on a cellulose fiber support, wherein silicic acid is present between the surface of each cellulose fiber constituting the cellulose fiber support and the fine particle titanium oxide photocatalyst. A photocatalytic cellulose fiber having a protective layer formed of calcium hydrate. 2. The photocatalytic cellulose fiber according to claim 1, wherein the fine particle titanium oxide photocatalyst is anatase type titanium oxide. 3. A solid content of 100 in a mixture of a siliceous raw material, a calcareous raw material, water, and the siliceous raw material and the calcareous raw material.
A raw material slurry containing a cellulose fiber raw material having a solid content of 10 to 125 parts by weight with respect to parts by weight is subjected to a hydrothermal treatment reaction to form a primary calcium silicate hydrate on the surface of each cellulose fiber constituting the cellulose fiber support. After obtaining a calcium silicate hydrate-coated cellulose fiber support having a structure in which particles are crystallized, fine particles of titanium oxide photocatalyst are supported on the surface of the calcium silicate hydrate-coated cellulose fiber support. A method for producing a photocatalytic cellulose fiber.