JP4852880B2 - Method for producing functional sheet, functional sheet, and functional filter - Google Patents

Description

The present invention relates to a functional filter or sheet having at least one function from deodorant properties, antibacterial properties, and fungicidal properties.

Dust as house dust, dead bodies such as mold, mites, and fine particles floating in the air such as pollen themselves generate a foul odor or become allergens to cause atopic dermatitis and asthma.

In addition, skin peeled from humans, sweat, and odors generated from indoor interior materials and various household items can cause discomfort to humans and cause sick house syndrome.

Conventionally, there are various filter materials for air purifiers that purify these fine particles floating in the air, but thin nonwoven fabrics are mainly used.

However, these nonwoven fabrics themselves do not have functions such as deodorizing properties and antibacterial properties, and it is necessary to attach various chemicals to the nonwoven fabrics in order to impart functionality, and there is a problem that the processing is difficult. Moreover, since it is a chemical fiber, there are many environmental loads.

In addition, many filter materials for air cleaners mainly use activated carbon as a deodorant. Filter materials in which sheets of fibrous activated carbon are laminated, filter materials in which granular activated carbon is incorporated in a filter unit, or photocatalytic filter materials Etc. are known.

However, activated carbon has a problem in that acidic substances are removed, but basic substances such as ammonia are difficult to remove and an off-flavor remains.

In addition, the photocatalytic filter material also requires an ultraviolet ray generator for promoting photoexcitation of titanium oxide, which requires light source energy and a large space.

In contrast, for example, two or more kinds of mixtures selected from silver zeolite of 10 μm or less, silver soluble glass fine particles, quartz andesite fine particles and activated carbon are included in the pulp raw material stage, and the fine particles are aggregated on the pulp surface by a papermaking method. A functional sheet that has been adsorbed and has a deodorizing and freshness maintaining function has been proposed (see, for example, Patent Document 1).

In addition, dust filters for vacuum cleaners for home use mainly use disposable paper filters, but dust and various filth are separated and collected in the air discharged after collecting dust. There was a problem of generating a dusty odor.

Furthermore, as the aging society progresses in the future, unpleasant urine odor accompanying urinary incontinence becomes a problem in the care of elderly people such as bedridden and dementia, and countermeasures are considered necessary. The main odor component of urine odor is ammonia.

For this, a cushion having a deodorizing / deodorizing effect using a fragrance such as highly safe natural essential oil (essential oil) has been devised (for example, see Patent Document 2).

If the deodorant is added in an amount sufficient to function in the pulp by the papermaking method, the yield is poor.

In addition, deodorization and deodorization with fragrances does not reduce the problem odor by simply masking the odor itself with a strong fragrance, but there are people who like and dislike the fragrance component itself, rather it is combined with the odor component In some cases.
JP 2000-325450 A Japanese Patent Laid-Open No. 2004-243095

The object of the present invention is to modify pulp fiber, which is a natural material with no environmental load, to impart deodorant and antibacterial properties to the pulp itself, and to further combine the deodorant and antibacterial agent by papermaking and impregnation methods It is intended to provide a functional paper sheet having improved characteristics by making it, a method for producing the same, and a functional filter processed from the sheet.

The invention according to claim 1 is a modified pulp comprising a structure in which at least one of the second and third carbinol groups of the pyranose ring in the cellulose skeleton which is a constituent unit of the pulp fiber is converted to a carbonyl group. This is a method for producing a functional sheet comprising modified pulp and activated carbon particles, wherein the activated carbon particles are added to the water-dispersed slurry, and the activated carbon particles are fixed on the modified pulp and then made by a papermaking method .

According to the second aspect of the present invention, the second and third carbons of the pyranose ring in the cellulose skeleton, which is a constituent unit of pulp fiber, are cleaved, and at least one of the second and third carbinol groups. Is produced by a papermaking method after adding activated carbon fine particles to an aqueous dispersion slurry of a modified pulp containing a structure converted to a carbonyl group, and fixing the activated carbon fine particles to the modified pulp And a method for producing a functional sheet comprising activated carbon fine particles .

The invention according to claim 3 is a functional sheet manufactured by the manufacturing method according to claim 1 or 2 .

The invention according to claim 11 is a functional filter characterized in that a large number of through holes having a hole diameter of 50 μm to 5 mm are provided by punching the entire surface of the functional sheet according to claim 3 .

Since the pulp material, which is a natural material, is modified to give the pulp itself deodorant and antibacterial properties, the work and cost of combining the deodorant and antibacterial agent can be reduced, and it can be discarded as paper waste. It becomes possible to reduce the environmental load.

Further, in the case of compounding with a deodorant or an antibacterial agent in order to further improve the function, it is possible to facilitate compounding because of the strong electrical polarity and reactivity of the pulp surface.

As the carbonyl group-containing oxidized modified pulp according to the present invention, a normal pulp raw material, that is, wood fiber can be used.

Specifically, bleached or unbleached sulfite pulp or kraft pulp, groundwood pulp, thermomechanical pulp (TMP), chemical thermomechanical pulp (CTMP), etc. of softwood or hardwood are used alone or in combination of two or more. You can match them.

In addition, in the case of mixing with the modified pulp fiber of the present invention using the carbonyl group-containing modified pulp and the unmodified pulp, in addition to the above-mentioned wood pulp, the non-wood fiber It is possible to use hemp, cotton (linter), straw, bamboo, kenaf, bacus, shiogusa, esparto, cocoon, cocoon, crust, ramie, and the like. Among them, rigid kenaf is preferable.

The modified pulp relating to the functional filter or sheet of the present invention has a carbonyl group. In claim 3 of the present invention, the range of the amount of the carbonyl group is defined by a value determined by the semicarbazide method. Yes.

The semicarbazide method is a quantitative method reported by Watanabe et al. In Hokkaido University in the Journal of Paper and Pulp Technology Association (published in 1956, Vol. 10, No. 67, 534). In particular, in the present invention, semicarbazide hydrochloride having a hydrazide group highly reactive with a carbonyl group is mainly converted to an aldehyde group obtained by converting a carbinol group by periodate oxidation. The amount of carbonyl groups is quantified by iodine titration with sodium thiosulfate after adding a certain amount and reacting, and adding a certain amount of iodic acid to the remaining semicarbazide and reducing it.

Further, in claim 3 of the present invention, the amount of carbonyl groups is shown in units of mmol / g, which indicates the amount of carbonyl groups contained per gram in the absolutely dry state of the modified pulp.

The carbonyl group quantified according to the above semicarbazide method is defined in the range of 0.05 to 6.5 mmol / g. This is because the modified pulp according to the present invention exhibits the intended effect of the present invention. Range.

When converted in terms of glucose, which is a constituent unit of cellulose, since the molecular weight of glucose units is 162, it is multiplied by 162 to 0.0081 to 1.05 mol / glucose units.

The amount of carbonyl group is preferably 0.5 to 3.0 mmol / g, and if it is less than 0.05 mmol / g, there is almost no improvement or improvement in physical properties due to the modification, and it exceeds 6.5 mmol / g. It tends to aggregate and is not preferable.

Although there are many methods for oxidizing pulp, the target oxidizing agent related to the present invention is used for the purpose of oxidizing the carbinol groups at the 2nd and 3rd positions on the pyranose ring of the cellulose skeleton in the pulp. It is different from the oxidant used in bleaching (bleaching) for the purpose of pulp delignification.

Specifically, periodic acid or periodate (such as sodium periodate or potassium periodate) can be used.

Examples of periodate include sodium metaperiodate and potassium metaperiodate, and sodium periodate having high solubility in water is preferable.

In the reaction of pulp and cellulose by periodate oxidation, 1,2-diol is oxidatively cleaved mainly to produce dialdehyde cellulose.

Periodic acid oxidation is known, and dialdehyde cellulose based on it is widely studied. However, those utilizing the aldehyde group of dialdehyde cellulose are disclosed in JP-A-7-324221 “Sulfonated cellulose and preparation method”. In addition, there is no other than the modified cellulose obtained by sulfonating dialdehyde cellulose.

We have already disclosed JP2001-131891, JP2001226893, etc. as inventions utilizing dialdehyde cellulose.

In the reaction of pulp and cellulose by periodate oxidation, side reactions such as cleavage of β-1,4-glycoside bond of cellulose occur slightly, and sodium periodate is unstable to light and decomposes. Therefore, it is desirable to operate at a temperature below room temperature in a dark place.

Further, since decomposition occurs due to cleavage of the main chain due to β-elimination particularly in an alkaline atmosphere, it is desirable to carry out the reaction on the neutral or acidic side if possible. Preferably, p. H. = Around 3.0 to 7.0.

The amount of periodic acid or sodium periodate added during the reaction increases the amount of carbonyl groups produced if the amount of addition is large and the oxidation reaction time is long, but degradation of the pulp fiber due to side reactions also occurs. Adjust to take into account the desired properties.

As reaction conditions for suppressing side reactions, a temperature below room temperature in the dark, preferably a reaction temperature around 5 ° C. is preferable.

In terms of reaction mechanism, equimolar periodic acid per unit of glucose of pulp or cellulose reacts theoretically, but when added in an amount of 1.0 mol or more per unit of glucose, the water dispersibility of the product becomes worse, and between pulp fibers. And aggregation between cellulose molecules occurs.

The oxidation reaction time is less affected if the amount of periodic acid or sodium periodate added is small, but if the amount added is 0.6 mol or more per glucose unit, the reaction starts from about 72 hours of oxidation reaction time. The water dispersibility of the product becomes lower. Desirably, periodate or sodium periodate is added in an amount of 0.05 to 0.6 mol per glucose unit, and the reaction time is suitably about 24 to 65 hours.

The present inventors have high charge polarity and reactivity by selectively oxidizing the second and third carbinol groups in the cellulose molecule which is the basic skeleton of the raw pulp as described above. Converted to a carbonyl group, and in particular, the second and third carbons in the cellulose skeleton were cleaved, and both the second and third carbinol groups or one of them was converted to a carbonyl group. In particular, it has been devised to impart deodorant and antibacterial properties to the pulp itself by utilizing an aldehyde group having high reaction activity.

The aldehyde group is a functional group that binds well to amines typified by ammonia that cannot be removed by activated carbon, which is frequently used as a deodorant, and glutaraldehyde used as a chemical sterilizer / disinfectant for medical devices. As described above, since the aldehyde group has a property of easily binding to protein, the modified pulp according to the present invention already has ammonia deodorizing property and antibacterial property.

Odor-causing substances such as mercaptans, sulfides, ammonia, amines, organic acids, aldehydes, indoles, ketones, alcohols, phenols, chain and cyclic hydrocarbons, etc. Therefore, when deodorization other than amines such as ammonia is required, activated carbon may be combined.

As a composite method of the activated carbon, a method of making a mixed paper with the modified pulp fiber according to the present invention or laminating the fibrous activated carbon sheet and the modified pulp sheet according to the present invention can be used.
At that time, as other reinforcing fibers, for example, glass fibers and ceramic fibers, biodegradable resins, various synthetic fibers, etc., and as binders latexes, for example, acrylic type, ethylene-vinyl acetate type, vinyl acetate type , Polyvinyl alcohol type, styrene-butadiene type and the like may be added.
In addition, various auxiliary agents and additives that are added during normal papermaking can also be added.

Examples of other deodorants that can be combined include porous materials such as zeolite and silica gel, or photocatalytic titanium oxide, zinc oxide, and polyvalent carboxylic acid.

Furthermore, the deodorizing porous fine particles according to the present invention are roughly classified into inorganic porous materials and organic porous materials. As inorganic porous materials, silica-based (silica, silica-alumina, silica-magnesia, silica・ Titania, etc.), alumina (alumina, boehmite, etc.), natural siliceous (natural zeolite, barley stone, sepiolite, palygorskite, permiculite, etc.), various synthetic siliceous (synthetic zeolite, artificial zeolite, hydrophobic zeolite, etc.) As the organic porous material, a polymer porous material such as styrene-divinylbenzene copolymer type porous fine particles can be used.
Any of these may be commercially available.

In order to further improve the antibacterial properties, for example, quaternary ammonium salts, imidazoles, metal zeolites, alcohols, phenols, thiazoles, hinokitiols, chitosan, chitin, propolis, catechins, etc. A known antibacterial agent may be combined.
Among them, hinokitiols and catechins are preferable because they are natural plant systems.

As a method for producing the functional sheet of the present invention, the same paper making method as in a normal paper making process can be used.

That is, after modifying the pulp fiber with periodic acid or periodate, the aqueous dispersion slurry of the aldehyde group-containing pulp may be made as it is, and in order to further improve the functionality, You may make mixed paper.

In this case, since the aldehyde group-containing pulp has a high electric polarity, the yield of the deodorant and antibacterial agent to be added is higher than that of the unmodified pulp.
Further, the paper sheet may be impregnated later with a deodorant / antibacterial agent or a solution thereof.

Further, as a method for producing the functional filter of the present invention, the sheet may be left as it is as long as air permeability is sufficient, but a minute hole may be formed in the sheet, and the sheet may be corrugated or pleated, or The honeycomb structure may be processed.

In particular, a method of distributing through holes having a hole diameter of 50 μm to 5 mm by punching or the like on the entire surface of the functional filter of the present invention is also possible. The hole diameter is preferably 100 μm to 1 mm, and the number of through holes depends on desired physical properties. Set.
Within this range, it is possible to achieve both deodorization / antibacterial properties and air permeability.

The present invention will be described below in accordance with specific examples, but the present invention is not limited thereto.

The raw material pulp is made from softwood kraft pulp (NBKP) papermaking raw material which is disaggregated according to JIS-P8209 “Handling method for pulp testing” and Canada according to JIS-P8121 “Pulp freeness test method”. A pulp slurry having a 1.0 wt% concentration was prepared by diluting with a standard freeness test method having a beating degree of 350 csf with water.

For this adjusted NBKP (N.V. = 1.0 wt%, beating degree = 350 csf) aqueous dispersion slurry 10 L (absolutely dry pulp amount = 100 g), sodium periodate was converted into glucose units (molecular weight = 162) in the pulp. ) About 26 g corresponding to 0.2 mol amount was added, stirred in a cool dark place with a stirrer to carry out an oxidation reaction, the modified pulp after 48 hours of reaction time was taken out, several ml of ethylene glycol was added and unreacted After decomposition of sodium periodate, the same volume of methanol is added to reprecipitate a small amount of oxidized modified pulp, filtered through a wire mesh of about 200 mesh, thoroughly washed with water, and about 1.0 wt% of modified pulp water A dispersed slurry was obtained.

Next, the modified pulp slurry was made into a paper with a basis weight of about 80 g / m ² with a standard hand-made square paper machine, dehydrated press (3.43 × 10 ⁵ Pa) was performed for 5 minutes, and a Yankee dryer ( The modified pulp paper according to the present invention was produced by drying at a surface temperature of about 120 ° C.

The carbonyl group-containing modified pulp slurry and activated carbon fine particles (trade name; Carbon Star, manufactured by Mitsui Mining Co., Ltd.) prepared in Example 1 according to the present invention were added to the carbonyl group-containing modified pulp (1.0 mmol / 4 times the amount corresponding to g) is added and fixed at room temperature for about 10 minutes, and the mixed slurry is made into a paper with a basis weight of about 80 g / m ² with a standard hand-made square paper machine, and dewatering press (3.43 × 10 ⁵ Pa) was performed for 5 minutes and dried with a Yankee dryer (surface temperature = about 120 ° C.) to prepare a modified pulp paper according to the present invention.

<Comparative Example 1>
The unmodified NBKP (degree of beating = 350 csf) water-dispersed slurry prepared in Example 1 was used as it was as an NBKP base paper by the same procedure as in Example 1.

<Comparative example 2>
As Comparative Example 2, a commercially available activated carbon fiber sheet was used.

Next, the deodorizing effect on ammonia and methyl mercaptan was tested as follows.

Samples of Examples 1 and 2 and Comparative Examples 1 and 2 were collected as 5 × 100 × 100 mm test pieces, and the test pieces, 200 ppm of ammonia odor and 200 ppm of methyl mercaptan odor were placed on a metal lid with a 500 ml glass mayonnaise. Seal in a bottle, leave it at room temperature for 30 minutes, suck 100 ml of gas, measure residual ammonia gas concentration and residual methyl mercaptan gas concentration with a gas detector tube (Kitakawa gas detector tube), and average value of each test piece Were comparatively evaluated.

Next, antibacterial properties were evaluated as follows.

Examples 1 and 2 and Comparative Examples 1 and 2 were sampled 5 pieces of 100 × 100 mm test pieces and evaluated based on the antibacterial test method for textiles (JIS L 1902), and the average value of each test piece was compared and evaluated. did.
At that time, the test bacterial species was evaluated using Staphylococcus aureus (yellow staphylococci).

The results are shown in Table 1.

Like the result of Table 1, it turned out that the functional sheet | seat of this invention of Example 1, 2 has reduced odor and antimicrobial property compared with Comparative Example 1,2.

Next, a hole having a diameter of 1 mm was formed in the modified pulp paper produced in Example 1, and a functional filter according to the present invention having an air permeability of 500 cm ³ / cm ² / second was obtained.
It was 70% when the weight collection efficiency of 15 types of dust specified in JIS based on JIS-B-9908 was evaluated.

A hole having a diameter of 1 mm was formed in the modified pulp paper produced in Example 2, and a functional filter according to the present invention having an air permeability of 450 cm ³ / cm ² / sec was obtained.
It was 70% when the weight collection efficiency of 15 types of dust specified in JIS based on JIS-B-9908 was evaluated.

Next, a deodorization test was performed as follows as a functional filter according to the present invention.

For the deodorization test, a sealed box having an internal volume of 1 m ³ is prepared, air supply holes and exhaust holes are provided on both sides of the box, the air supply holes and the exhaust holes are connected by a blower pipe, and a blower is provided between them. A device capable of circulating air was used.
In the test method, ammonia gas and methyl mercaptan gas of a predetermined concentration in the box were sealed, and the functional filter was interposed in the air supply hole, and 100 ml of the gas after being circulated for a specified time at a flow rate of 1 m ³ per minute was sucked. The deodorization situation was investigated by measuring the residual ammonia gas concentration and residual methyl mercaptan gas concentration with a gas detector tube (Kitakawa gas detector tube).
Moreover, the case where a functional filter was not interposed was measured as a blank.

The results are shown in Table 2.

As the result of Table 2, it turned out that the functional filter of this invention of Example 3, 4 has remarkably reduced odor compared with the blank.

The functional paper sheet of the present invention and the functional filter processed from this sheet are air purifiers, fan heaters, air filters such as air conditioners that require deodorization and antibacterial properties, disposable paper filters for vacuum cleaners, It can be used in a wide range of applications such as deodorizing sheets for paper diapers, deodorizing sheets for refrigerators, and nursing sheets.

Claims (4)

Activated carbon fine particles are added to a water-dispersed slurry of modified pulp containing a structure in which at least one of the 2nd and 3rd carbinol groups of the pyranose ring in the cellulose skeleton, which is a constituent unit of pulp fiber, is converted to a carbonyl group. A method for producing a functional sheet comprising modified pulp and activated carbon fine particles, wherein the activated carbon fine particles are fixed to the modified pulp and then made by a papermaking method. Structure in which the second and third carbons of the pyranose ring in the cellulose skeleton, which is a constituent unit of pulp fiber, are cleaved, and at least one of the second and third carbinol groups is converted to a carbonyl group A functional sheet comprising a modified pulp and activated carbon fine particles, wherein activated carbon fine particles are added to a water-dispersed slurry of a modified pulp containing, and made by a papermaking method after fixing the activated carbon fine particles to the modified pulp. Production method. A functional sheet manufactured by the manufacturing method according to claim 1 . A functional filter, wherein a large number of through holes having a hole diameter of 50 μm to 5 mm are formed by punching the entire surface of the functional sheet according to claim 3 .