JP2001198203A - Fire-retardant deodorizing sheet and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fire-retardant deodorizing sheet having sufficient fire retardancy and good durability and a method of manufacturing the same. SOLUTION: A fire-retardant deodorizing sheet is constituted by fixing adsorbing particles and fire-retardant particles to a sheet base fabric 1 by using both of a binder 4 of which the weight reduction ratio by hot water treatment containing caustic soda is 1% or less and a binder of which the weight reduction ratio is 1- below 3%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame retardant deodorant sheet having deodorant properties and flame retardancy, and more particularly, to a flame retardant deodorant sheet in which a deodorant and a flame retardant are fixed to a sheet with a binder. It relates to an odor sheet body.

[0002]

2. Description of the Related Art In recent years, deodorizing materials (adsorbents) have been used in a wide range of fields due to increasing environmental problems. Such deodorants include charcoal, activated carbon,
In many cases, mineral fine powder or the like is used by being fixed to a sheet body. As a sheet having such a deodorizing function, for example, a sheet as described in JP-B-7-24476, that is, a gas-adsorbing sheet obtained by making fine powder of charcoal or the like together with pulp. Is presented. This gas-adsorbing sheet has a function of absorbing odor, has a relatively small thickness, can be freely wound and folded, and has excellent handling properties.

[0003] However, since the fine powder of charcoal is simply attached between the fibers of the pulp, the fine powder easily falls off from the sheet body and is not satisfactory in terms of durability. In particular, there is a lack of durability during cleaning. On the other hand, in this type of sheet body including the above-mentioned gas adsorbing sheet, there is a large problem that fine powder of charcoal or the like for deodorization is easily burned. That is, charcoal and activated carbon having a deodorizing function are combustibles, and once lit, it is extremely difficult to extinguish a fire. As described above, the conventional adsorptive sheet is satisfactory in terms of adsorptivity, but has a problem in that it lacks durability and is flammable.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above technical background. That is, an object of the present invention is to provide a deodorant (adsorption) sheet body with sufficient flame retardancy. Still another object of the present invention is to provide a flame-retardant deodorant sheet having good durability and a method for producing the same.

[0005]

According to the present invention, as a result of intensive studies to solve the above-mentioned problems, in addition to the adsorbent particles, the flame retardant particles are adhered to the sheet base fabric with a binder satisfying certain conditions. As a result, it has been found that flame retardancy can be sufficiently imparted and durability is obtained, and this finding has led to the present invention.

That is, the present invention relates to (1) a flame-retardant deodorant sheet in which an adsorbent and a flame retardant are fixed to a sheet base cloth, which is selected on the basis of the degree of weight reduction by hot water treatment containing caustic soda. The present invention resides in a flame-retardant deodorant sheet in which the adsorbent and the flame retardant are fixed using a binder.

(2) A flame-retardant deodorizing sheet in which adsorbed particles and flame-retardant particles are fixed to a sheet base cloth, wherein a binder whose weight loss rate by hot water treatment containing caustic soda is 1% or less is provided. The present invention resides in a flame-retardant deodorizing sheet in which the adsorbed particles and the flame-retardant particles are fixed using both a binder having a weight reduction ratio of 1% or more and less than 3%.

Further, (3) the flame-retardant deodorant sheet according to (2), wherein the basis weight of the sheet base fabric is 10 to 800 g / m ² .

Also, (4) the particle size of the adsorbed particles is 1
The flame retardant deodorant sheet according to the above (2), which has a particle diameter of not more than 00 μm and an average particle diameter of 5 to 30 μm.

[0010] (5) The flame-retardant deodorant sheet according to (2), wherein the amount of adsorbed particles carried is 10 to 50 g / m ² .

Also, (6) the particle size of the flame-retardant particles is 3
It is present in the flame-retardant deodorant sheet according to the above (2), wherein the average particle diameter is 0.0 μm or less and the average particle diameter is 0.1 to 5.0 μm.

(7) The flame-retardant deodorant sheet according to (2), wherein the amount of the flame-retardant particles is ² to 50 g / m ² .

(8) The flame-retardant deodorant sheet according to (2), wherein the adsorbed particles are charcoal, activated carbon or a porous inorganic compound.

(9) A flame-retardant deodorant sheet comprising adsorbed particles and flame-retardant particles fixed to a sheet base fabric,
The adsorbed particles and the flame-retardant particles are fixed using both a binder having a weight reduction rate of 1% or less by hot water treatment containing caustic soda and a binder having a weight reduction rate of 1% or more and less than 3%. And the basis weight of the sheet base fabric is 10
８００800 g / m ² , the particle size of the adsorbed particles is 100 μm or less, the supported amount of the adsorbed particles is 10 to 50 g / m ² , and the supported amount of the flame retardant particles is ² to 50 g / m ^2. Exist in the body.

(10) a step of mixing the adsorbed particles and the flame-retardant particles with a binder, a step of adhering the binder containing the adsorbed particles and the flame-retardant particles to a sheet base cloth, and drying the sheet base cloth. And a step of curing the dried sheet base fabric.

(11) As the binder, both a binder having a weight reduction rate of 1% or less by hot water treatment containing caustic soda and a binder having a weight reduction rate of 1% or more and less than 3% are used. (10) The method for manufacturing a flame-retardant deodorant sheet according to the above (10).

Here, the invention may employ a configuration in which two or more selected from the above 1 to 9 are combined as long as the object is met.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The flame retardant deodorant sheet of the present invention is characterized in that adsorbed particles as an adsorbent and flame retardant particles as a flame retardant are fixed to a sheet base fabric. More specifically, the present invention is characterized in that the adsorbed particles and the flame-retardant particles are fixed using a binder selected based on the degree of weight reduction by hot water treatment containing caustic soda. Here, the binder selected in consideration of the degree of weight loss includes a binder having a weight reduction rate of 1% or less by hot water treatment containing caustic soda and a binder having a weight reduction rate of 1% or more and less than 3%. It is a binder using both.

Here, the form of the sheet base fabric constituting the flame-retardant deodorizing sheet of the present invention is, for example, a breathable material such as a knitted fabric, a woven fabric, a woven fabric, a nonwoven fabric, a felt, or a combination thereof. Some are adopted. As the material, natural fibers such as wool, cotton and hemp, recycled fibers such as rayon, synthetic fibers such as polyester and polyamide, and the like may be naturally used. A sheet base fabric made of such a fiber material has flexibility (processability), is lightweight, and has high air permeability. Also, the basis weight of the sheet base fabric is 10 to 500 in consideration of the ease of handling.
g / m ² , preferably 20 to 300 g
/ M ² is adopted.

Next, as the adsorbent (adsorbed particles) for imparting a deodorizing function fixed to the sheet base cloth, any conventionally known adsorbent can be used. For example, silica gel (SiO ₂ .nH ₂ O), sepiolite (Mg ₈ H ₂ (Si ₄ O ₁₁ ) ₃ .3H ₂ O), zeolite (Na ₂ Al ₂ Si ₃ O ₁₀ .xH ₂ O) which is an inorganic compound Further, charcoal or activated carbon obtained by carbonizing an organic compound is used. Incidentally, the characteristics of these substances are that they are porous and have an adsorption function, have an ion exchange function, and have a catalytic function.

Here, the adsorbent is used in the form of particles. The amount of the adsorbent particles to be applied to the sheet substrate (ie, the amount of the adsorbent) depends on the type of the sheet substrate.
50 g / m ² is employed. If the supported amount is less than 10 g / m ² , the deodorizing power is reduced, and if it exceeds 50 g / m ² , the air permeability is reduced. The particle size of the adsorbed particles is preferably 100
μm or less, and an average particle size of 5 to 30 μm is employed.
More preferably, the particle size is 1 to 50 μm, and the average particle size is 10 to 10 μm.
20 μm. If the particle size exceeds 100 μm, many of the particles fall off from the surface to be applied due to friction or the like, and the workability deteriorates. On the other hand, if the particle size is too small, the deodorizing and humidity controlling effects are reduced.

As a flame retardant for providing a flame retardant function by being fixed to a sheet base cloth, a urethane resin, an acrylic resin, or the like is used as a binder for flame retardant processing of synthetic fibers and natural fibers (main processing). Suitable organic phosphorus compounds are suitable.
For flame retarding treatment (pre-processing) of cotton and rayon, acidic ammonium phosphate, borate, ammonium sulfamate, antimony compound, ammonium halide, alumina trihydrate and the like are suitable.

Here, the flame retardant is used in the form of particles. The amount of the flame retardant particles applied to the sheet base fabric (that is, the amount of support) depends on the type of the sheet base fabric, but is 2 to 5 times.
0 g / m ² is adopted. If the loading is less than ² g / m ² , the flame retardancy will be low, and if it exceeds 50 g / m ² , the texture will be coarse and hard, and the air permeability will also decrease. The particle size of the flame-retardant particles is preferably 30.0 μm or less, and the average particle size is 0.1 to
5.0 μm is adopted. More preferably, the particle size is between 0.
The average particle size is 0.1 to 2.0 μm. If the particle size exceeds 30.0 μm, many of the particles fall off the surface to be applied due to friction or the like, and the workability deteriorates. On the other hand, if the particle size is too small, the flame retardancy decreases.

In the present invention, specific conditions are required as a binder for fixing the adsorbent particles as the adsorbent and the flame-retardant particles as the flame retardant to the sheet base cloth. That is, a binder selected based on the degree of weight reduction due to hot water treatment including caustic soda is employed.

More specifically, a binder ("a
It is preferable to use both a binder ("b-type binder") and a binder having a weight reduction ratio of 1% or more and less than 3% ("b-type binder"). Examples of the a-type binder and the b-type binder are as follows. Group a ... Acrylic resin (acrylate,
Acrylic acid and other copolymers) Vinyl acetate resins and other copolymers thereof Group B: Copolymer of polyacrylic acid and styrene,
Copolymer of polyacrylic acid and acrylonitrile

In the present invention, the reason why the binder having the above conditions is selected is as follows. Theoretically, when the sheet is washed, if the weight of the binder is reduced by the washing liquid (alkaline aqueous solution), the adsorbed particles and the flame-retardant particles cannot be reliably held, and they are detached. The smaller the weight loss rate, the better.

As a result of many experiments conducted by the present inventor, the weight loss rate by hot water treatment containing caustic soda (a solution of 40 g caustic soda per liter of water) was 3%.
It was found that those described above were unsuitable as binders from the viewpoint of durability, and that binders having a weight reduction ratio of less than 3% were suitable. Experiments also show that when the weight loss rate is less than 3%, it is most preferable to use a binder containing both a binder having a weight loss rate of 1% or less and a binder having a weight loss rate of 1% or more and less than 3%. It was. Therefore, by using the above binder,
The adsorbed particles and the flame-retardant particles can be fixed to the sheet member accurately and in a durable state.

In order to provide the sheet body with an adsorption function and a flame-retardant function and to obtain durability, a treatment liquid containing a binder, an adsorbent and a flame-retardant is applied to the sheet base cloth so that the amount of collateral is as uniform as possible. (Coating).

The basic formulation of the treatment liquid is as follows (the weight ratio is in a preferred range). Adsorbent 18 to 28% by weight Binder a 5 to 15% by weight Binder 10 to 15% by weight Flame retardant 5 to 10% by weight Water balance １００ 100% by weight (solid content)

[Production Method of Flame Retardant Deodorant Sheet] Next, a method of producing the flame retardant deodorant sheet of the present invention will be described. The flame-retardant deodorant sheet body includes: 1) a step of mixing adsorbed particles, flame-retardant particles and a binder, 2) a step of adhering a binder containing adsorbed particles and flame-retardant particles to a sheet base fabric, and 3) adhering of a binder. It is manufactured by obtaining a step of drying the dried sheet base cloth and a step of curing the dried sheet base cloth.

The sheet base fabric may be made of a flame-retardant fiber, or may be made of a non-flame-retardant fiber in which a flame retardant is fixed with a binder a and a binder b according to the present invention. .

Hereinafter, each step will be described. 1) A step of mixing the adsorbed particles, the flame-retardant particles, and the binder, and the adsorbent particles and the flame-retardant particles obtained by pulverizing the adsorbent and the flame retardant to a predetermined particle size are mixed with the binder. As described above, as the binder, as described above, a binder having a weight reduction ratio of less than 3% after hot water treatment containing caustic soda (treatment with a solution of 40 g of caustic soda per liter for 3 hours) is used. In addition, as described above, the use of a combination of an a-type binder and a b-type binder further improves the durability.

2) A step of adhering a binder containing the adsorbed particles and the flame-retardant particles to the sheet substrate, and applying the binder (including the adsorbed particles and the flame-retardant particles) prepared in the above step 1 to the sheet substrate. It is applied so as to make the amount of loading as uniform as possible. Specifically, it is applied by using an optimal one from among a pad mangle method, a gravure roll method, a printing method, a spraying method, a coating method and the like.

3) A step of drying the sheet base cloth to which the binder has been attached, and a step of drying the sheet base cloth provided with the adsorbed particles and the flame-retardant particles formed in the step 2 by, for example, 100 to 1
Dry at 30 ° C. for an appropriate time (for example, about several minutes). Through this drying, the binder is hardened, and the adsorbed particles and the flame-retardant particles are fixed to the sheet base fabric.

4) Step of curing the dried sheet base cloth. The sheet base cloth dried in the above step 3 is cured at 140 to 160 ° C. for an appropriate time (for example, about several minutes). Through the steps 1 to 4 described above, a binder is applied to the sheet base fabric, and the adsorbed particles and the flame-retardant particles are securely fixed by using the binder as a fixing bed, and a flame-retardant deodorant sheet is completed. Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples. However, the present invention is not necessarily limited to the embodiments, and other embodiments are possible as long as they meet the purpose.

[0036]

EXAMPLES and COMPARATIVE EXAMPLES First, methods for measuring various characteristics described in the present invention are as follows.

[Evaluation of Flame Retardancy] 45 ° micro burner method: JIS L-1091 A-
1 method Coil method: JIS L-1091 D method FMVSS method: Conforms to the American automobile safety standard N0.302 method

[Ammonia deodorizing property] The ammonia concentration is 4
The sample was placed in a 500 cc plastic container in an atmosphere of 00 ppm, and the temperature was measured at 23 ° C. for 30 minutes using an ammonia concentration detection tube manufactured by Gastech Co., Ltd.

[Acetaldehyde deodorizing property] A sample is placed in a 500 cc plastic container in an atmosphere having an acetaldehyde concentration of 90 ppm, and an acetaldehyde concentration detection tube (manufactured by Gastech Co., Ltd.) after a temperature of 23 ° C and 30 minutes.
Was measured by

[Method of Adjusting Flame-Retardant Deodorant Sheet Base Fabric] Table-1. The one shown in the following was used.

[0041]

[Table 1]

The details of the adsorbent and the binder used in the present invention are as follows. Charcoal: Carbotech 21 (manufactured by Hinomaru Carbo Techno Co., Ltd.) Particle size 30 μm or less, average particle size 9.7 μm Active charcoal: Kuraray Coal Activated Carbon 4TF (Kuraray Chemical Co., Ltd.) Particle size 70 μm or less, average particle size 20 μm Sepiolite : Miraclay P-300 (manufactured by Omi Mining Co., Ltd.) Particle size: 75 μm or less, average particle size: 28 μm Binder: Binder a type: Z5211-2R1 (manufactured by Takamatsu Yushi Co., Ltd.) Acrylic resin Binder type: Ultra Sol M46 (manufactured by Ganz Kasei Co., Ltd.) Copolymer of polyethyl acrylate and styrene Binder c type: Seikaplane ER-50 (manufactured by Dainippon Seika Co., Ltd.) Acrylic ester copolymer Binder c type refers to hot water treatment containing caustic soda (solution of 40 g caustic soda per liter of water)
3% is the above binder.

Table 2 shows the details of the flame-retardant particles used in the flame-retardant treatment (main treatment) for cotton and various sheet base fabrics.

[0044]

[Table 2]

[0045]

Embodiment 1 Table-1. Was used to prepare a treatment liquid having the following composition on the sheet base cloth, and this treatment liquid was applied to the sheet base cloth by a pad mangle method. Carbotec 21 22% by weight (solid content) Z5211-2R1 7% by weight (solid content) Ultrasol M46 10% by weight (solid content) Nonnene R976- 5 7% by weight (solid content) Water residue １００ Total 100% by weight

Next, the sheet base cloth provided with the above adsorbed particles and flame retardant particles is dried at 120 ° C. for 2 minutes.
Curing was performed at 150 ° C. for 2 minutes to obtain a durable flame-retardant deodorant sheet. Table 4 shows the conditions of the sheet base fabric, and Tables 6 to 8 show the performance. Further, Table 3 shows a list of the sheet base fabric, the adsorbent, the flame retardant, and the binder in Examples and Comparative Examples.

[0047]

Example 2 A flame-retardant deodorant sheet was prepared in the same manner as in Example 1 except that Kuraray Coal 4TF was used instead of Carbotech 21 as an adsorbent. Table-4 shows the conditions of the sheet base fabric. Table 6 shows the performance. Or Table-8. It was shown to.

[0048]

Example 3 A flame-retardant deodorant sheet was prepared in the same manner as in Example 1 except that Miraclay P-300 was used instead of Carbotech 21 as an adsorbent. Table-4 shows the conditions of the sheet base fabric. Table 6 shows the performance. Or Table-8. It was shown to.

[0049]

Embodiment 4 Table-1. Polyester shown in (PET)
/ In order to carry out flame-retardant treatment of the rayon nonwoven fabric (final processing), a treatment liquid having the following composition is applied by a pad mangle method, dried at 120 ° C. for 2 minutes, and cured at 150 ° C. for 2 minutes. Then, a sheet base fabric was obtained. Furan EM1500TR 14% by weight (solid content) Z5211-2R1 7% by weight (solid content) Ultrasol M46 10% by weight (solid content) Water residue ──────────────────── １００Total 100% by weight A flame-retardant deodorant sheet was prepared in the same manner as in Example 1 except that this sheet base cloth was used. Table-4 shows the conditions of the sheet base fabric. Table 6 shows the performance. Or Table-8. It was shown to.

[0050]

Embodiment 5 Table-1. Cotton 10 shown in
A flame-retardant deodorant sheet was prepared in the same manner as in Example 4 except that a 0% woven fabric was used. Table-4 shows the conditions of the sheet base fabric.
Table 6 shows the performance. Or Table-8. It was shown to.

[0051]

Embodiment 6 Table-1. The acrylic non-woven fabric shown in Table 2 was further used as a flame retardant. A flame-retardant deodorant sheet was prepared in the same manner as in Example 1, except that B (Nikka Finon CG-5) was used. Table-4 shows the conditions of the sheet base fabric. Table 6 shows the performance. Or Table-8. It was shown to.

[0052]

Embodiment 7 Table-1. The durability and flame-retardant deodorizing sheet was prepared in the same manner as in Example 1 except that the acrylic fabric shown in (1) was used. Table shows the conditions of the sheet base fabric.
4. Table 6 shows the performance. Or Table-8. It was shown to.

[0053]

Comparative Example 1 Table-1. A non-flammable deodorant sheet was prepared in the same manner as in Example 1, except that only the a-type polyester nonwoven fabric shown in (1) was used as a binder. Table-5 shows the conditions of the sheet base fabric. Table 6 shows the performance. Or Table-8. It was shown to.

[0054]

Comparative Example 2 Table-1. A deodorant sheet was prepared in the same manner as in Example 1 except that the polyester nonwoven fabric shown in (1) was used and the flame retardant was removed. Table-5 shows the conditions of the sheet base fabric. Table 6 shows the performance. Or Table-8. It was shown to.

[0055]

Comparative Example 3 Table-1. A deodorant sheet was prepared in the same manner as in Comparative Example 2 except that the polyester / rayon nonwoven fabric shown in (1) was used. Table-5 shows the conditions of the sheet base fabric. Table 6 shows the performance. Or Table-8. It was shown to.

[0056]

Comparative Example 4 Table-1. A deodorant sheet was prepared in the same manner as in Comparative Example 2 except that the cotton fabric shown in (1) was used. Table-5 shows the conditions of the sheet base fabric. Table 6 shows the performance. Or Table-8. It was shown to.

[0057]

Comparative Example 5 Table-1. A deodorant sheet was prepared in the same manner as in Comparative Example 2, except that the polyester nonwoven fabric shown in (1) was used and Kuraray Coal activated carbon 4TF was used as an adsorbent. Table-5 shows the conditions of the sheet base fabric. To
Table 6 shows performance. Or Table-8. It was shown to.

[0058]

Comparative Example 6 Table-1. A deodorant sheet was prepared in the same manner as in Example 1, except that the polyester nonwoven fabric shown in (1) was used, and Seikaplane ER-50 of Group c was used as a binder. Table-5 shows the conditions of the sheet base fabric. Table 6 shows the performance. Or -8. It was shown to.

[0059]

The flame-retardant deodorant sheet obtained according to the present invention has deodorant properties and excellent flame retardancy.
Further, even in normal handling, the adsorbent (adsorbed particles) and the flame retardant (flame retardant particles) are prevented from falling off, thereby ensuring durability. Table-8. And Table-6. And Table-7. It was found from the comparison with that that the initial deodorant property and flame retardancy were retained even after 10 washes.

[0060]

[Table 3]

[0061]

[Table 4]

[0062]

[Table 5]

[0063]

[Table 6]

[0064]

[Table 7]

[0065]

[Table 8]

[0066]

[Brief description of the drawings]

FIG. 1 is a schematic view showing a flame-retardant deodorant sheet of the present invention.

[Explanation of symbols]

 1. 1. Sheet base cloth 2. Adsorbed particles (adsorbent) 3. Flame retardant particles (flame retardant) Binder A. Flame retardant deodorant sheet

Claims (11)

[Claims] 1. A flame-retardant deodorant sheet comprising an adsorbent and a flame retardant fixed to a sheet base cloth, wherein the adsorbent and the binder are selected using a binder selected based on the degree of weight reduction due to hot water treatment using caustic soda. A flame-retardant deodorant sheet body having a flame retardant fixed thereon. 2. A flame-retardant deodorizing sheet in which adsorbed particles and flame-retardant particles are fixed to a sheet base cloth, wherein a binder having a weight loss rate of 1% or less by hot water treatment containing caustic soda; Wherein the adsorbed particles and the flame-retardant particles are fixed using both a binder having a content of 1% or more and less than 3%. 3. A sheet base fabric having a basis weight of 10 to 800 g / m.
^3. The flame-retardant deodorant sheet according to claim 2, wherein 4. The flame-retardant deodorant sheet according to claim 2, wherein the adsorbed particles have a particle size of 100 μm or less and an average particle size of 5 to 30 μm. 5. The method according to claim 1, wherein the amount of the adsorbed particles is 10 to 50 g / m ^2.
The flame retardant deodorant sheet according to claim 2, wherein: 6. The flame-retardant deodorizing sheet according to claim 2, wherein the particle diameter of the flame-retardant particles is 30.0 μm or less, and the average particle diameter is 0.1 to 5.0 μm. 7. The flame-retardant deodorant sheet according to claim ² , wherein the carried amount of the flame-retardant particles is ² to 50 g / m ² . 8. The flame-retardant deodorant sheet according to claim 2, wherein the adsorbed particles are charcoal, activated carbon or a porous inorganic compound. 9. Adsorbed particles and flame-retardant particles are fixed to a sheet base cloth.
Flame retardant deodorized sheet, which contains caustic soda
Binder whose weight reduction rate by hot water treatment is 1% or less
And a binder having a weight reduction ratio of 1% or more and less than 3%
Using both, the adsorbed particles and the flame-retardant particles are fixed
And the basis weight of the sheet base fabric is 10 to 800 g / m.^Two,
The particle size of the adsorbed particles is 100 μm or less,
Capacity is 10 to 50 g / m ^TwoThe loading amount of the flame-retardant particles is 2 to 5
0 g / m^TwoA flame-retardant deodorant sheet body, characterized in that: 10. A step of mixing adsorbed particles and flame-retardant particles with a binder, a step of attaching a binder containing the adsorbed particles and flame-retardant particles to a sheet base cloth, a step of drying the sheet base cloth, A method for producing a flame-retardant deodorant sheet body, comprising a step of curing a sheet base fabric. 11. A binder having a weight reduction ratio of 1% or less by hot water treatment containing caustic soda;
The method for producing a flame-retardant deodorant sheet according to claim 10, wherein both a binder having a weight reduction ratio of 1% or more and less than 3% are used.