JP6607422B1 - Formaldehyde scavenger - Google Patents

Abstract

The present invention provides a formaldehyde scavenger capable of capturing formaldehyde efficiently over a long period of time under daily humidity conditions such as ambient air and room air. A formaldehyde scavenger in which urea is supported on a porous carbon material, and preferably an acidic reagent is supported together with urea. [Selection] Figure 2

Description

  The present invention relates to a formaldehyde scavenger that traps formaldehyde present in the atmosphere or the like.

  Formaldehyde (HCHO) is one of allergens that are highly harmful, such as causing chemical sensitivity and allergic contact dermatitis. In addition to being produced as a synthetic raw material, formaldehyde is emitted from combustion of coal, heavy oil, etc., and automobile exhaust gas. In addition, it is known that it is produced by a photochemical reaction from hydrocarbons released into the atmosphere from automobile exhaust gas. Furthermore, they are used in large quantities as resins and adhesives for residential furniture and wall materials, or as raw materials for plastics. Formaldehyde has high volatility, so it tends to be highly concentrated in residential spaces with poor ventilation, living spaces such as in cars, etc., and sick houses that cause allergies and health effects in living spaces are a major problem and effective reduction Establishment of technology is required.

  To date, as a reduction measure, a technique for coating a building material of a house with titanium oxide or iron ions that oxidize and decompose formaldehyde to render it harmless has attracted attention (for example, see Patent Document 1). However, titanium oxide requires sunlight, and the titanium oxide coated surface has poor air permeability and has a problem that contact efficiency with air is extremely low. Furthermore, the generation and release of unknown harmful chemical substances by incomplete oxidation is a major problem.

  As other purification technologies, research has also been conducted on capture materials using activated carbon, rush, tea catechins, etc. (see, for example, Patent Document 2), which can capture formaldehyde efficiently over a long period of time. Has not been developed.

  Furthermore, since formaldehyde has a property of being trapped by urea in a slight amount, a trapping agent in which urea is mixed with a paint agent has been studied. However, although formaldehyde can be trapped very slightly in a situation of 0% humidity. Under the humidity conditions in the daily living environment (hereinafter, sometimes referred to as daily humidity conditions), the performance was hardly exhibited. Moreover, formaldehyde could not be supplemented for a long time.

JP 2007-016460 A JP 2002-126059 A

  An object of the present invention is to provide a formaldehyde scavenger capable of capturing formaldehyde efficiently over a long period of time under daily humidity conditions such as ambient air and room air.

  As a result of various investigations on formaldehyde trapping means that adversely affect life, the present inventors have made a material in which urea is supported on a porous carbon material such as activated carbon fiber (Activated Carbon Fiber; ACF). It has been found that formaldehyde can be efficiently captured over a long period of time under daily humidity conditions such as ambient air and room air, and the present invention has been completed. Furthermore, it discovered that the capture | capture capability was further improved by carrying | supporting nitric acid in addition to urea.

That is, the present invention is as follows.
[1] A formaldehyde trapping material, characterized in that urea is supported on a porous carbon material.
[2] The formaldehyde scavenger according to [1], wherein an acidic reagent is further supported on the porous carbon material.
[3] The formaldehyde scavenger according to [2], wherein the acidic reagent is nitric acid.
[4] The formaldehyde scavenger according to any one of [1] to [3], wherein the porous carbon material is fibrous activated carbon.
[5] The formaldehyde scavenger according to any one of [1] to [4], wherein the porous carbon material is fired under an inert gas.
[6] The formaldehyde scavenger according to [5], wherein the firing temperature of the porous carbon material is 150 to 1500 ° C. and the firing time is 0.5 to 5 hours.
[7] An air filter comprising the formaldehyde scavenger according to any one of [1] to [6].

  The formaldehyde trapping material of the present invention can trap formaldehyde efficiently over a long period even under daily humidity conditions such as ambient air and room air.

It is explanatory drawing of the apparatus used for the formaldehyde aeration test (indoor test) in an Example. It is a figure which shows the relationship between the urea concentration (urea solution density | concentration) of the formaldehyde capture | acquisition material (pitch type | system | group) which carry | supported urea, and the formaldehyde capture | capture ability in a laboratory test (relative humidity 0%). It is a figure explaining the principle of formaldehyde capture | acquisition of the formaldehyde capture | acquisition material of this invention. It is a figure which shows the trapping ability of formaldehyde of materials (urea carrying | supporting, unloading) other than a porous carbon material and a porous carbon material (urea unloading) in a laboratory test (relative humidity 0%). It is a figure which shows the capture | acquisition ability of formaldehyde of the formaldehyde capture | acquisition material (pitch type) which carry | supported urea and nitric acid in a laboratory test (relative humidity 0%). It is a figure which shows the capture | acquisition ability of formaldehyde of the formaldehyde capture | acquisition material (cellulose type | system | group) which carry | supported urea and nitric acid in a laboratory test (relative humidity 0%). It is a figure which shows the capture | acquisition ability of formaldehyde of the formaldehyde capture | acquisition material (pitch type | system | group) which carry | supported urea in a laboratory test (relative humidity 40%). It is a figure which shows the capture | acquisition ability of formaldehyde of the formaldehyde capture | acquisition material (pitch type | system | group) which carry | supported urea and nitric acid in a laboratory test (relative humidity 40%).

  The formaldehyde scavenger of the present invention is characterized in that urea is supported on a porous carbon material. In the present invention, “supporting urea on the porous carbon material” means that urea is physically and / or chemically attached to the porous carbon material. In the capturing material of the present invention, urea is supported mainly on the pore inner walls of the porous carbon material (see FIG. 3).

  The formaldehyde trapping material of the present invention can trap formaldehyde efficiently over a long period even under daily humidity conditions. For example, it is effective even in an environment where the relative humidity is 10% or more, preferably 20% or more, more preferably 30% or more, and even more preferably 40% or more. Therefore, the formaldehyde scavenger of the present invention is suitable as a filter material for air filters that remove formaldehyde contained in gases and air in daily environments, and in particular, filters for air filters such as air purifiers, air conditioners, and dehumidifiers. Suitable as a material. In addition, it can be used as a material for daily necessities such as curtains, indoor walls, furniture inner walls, car mats, chair seats and the like.

<Porous carbon material>
The porous carbon material of the present invention has pores for supporting urea. Examples of the porous carbon material include fibrous, granular, and powdered activated carbon, and fibrous activated carbon (ACF) is preferable because the effects of the present invention can be more effectively exhibited. The activated carbon may be derived from any of pitch-based, cellulose-based, polyacrylonitrile-based (PAN-based), phenolic resin-based, plant-derived and the like, but among these, the effect of the present invention is more effectively achieved. Pitch and cellulose are preferable because they can be exhibited.

The porous carbon material of the present invention preferably has a specific surface area of about 300 to 3000 m ² / g, for example. Moreover, it is preferable that an average pore diameter is about 0.6-6 nm.

  The porous carbon material of the present invention may be unfired, but is preferably fired under an inert gas such as nitrogen gas or argon gas. As a result, the oxygen element (carboxyl group, carbonyl group, heterocycle), nitrogen element (heterocycle), and hydrogen element contained in the porous carbon material are decomposed and separated, making the carbon material hydrophobic and compatible with urea. , Formaldehyde scavenging ability can be improved.

  As the firing time, it is only necessary to be able to remove oxygen element or the like attached to the porous material, and depending on the firing temperature, for example, about 0.5 to 5 hours is preferable, and 0.5 to 2 hours is more preferable. . Moreover, as a calcination temperature, 150-1500 degreeC is preferable, 300-1500 degreeC is more preferable, 300-1200 degreeC is further more preferable.

<Urea>
The urea of the present invention is a substance represented by the chemical formula (NH ₂ ) ₂ CO, and a commercially available product can be used. Since urea is cheaper than other amines and has high safety, the formaldehyde trapping material of the present invention including the urea is suitable as a filter material for air filters and a material for household goods. Urea is safe and harmless because it does not generate new substances (including formaldehyde) by reaction with such gases even in an environment containing various gases, and is suitable for use in everyday environments. It is.

  The urea content in the formaldehyde scavenger of the present invention is not particularly limited as long as it can effectively exert the effects of the present invention. For example, 50 to 300 mg is preferable with respect to 1 g of the porous carbon material. 50 to 200 mg is more preferable, and 120 to 180 mg is more preferable.

<Acid reagent>
In the formaldehyde scavenger of the present invention, it is preferable to carry an acidic reagent on the porous carbon material in addition to urea. Thereby, formaldehyde can be captured more effectively and over a long period of time.

  Examples of the acidic reagent of the present invention include nitric acid, hydrochloric acid, sulfuric acid, acetic acid and the like. Among these, nitric acid is preferable because the effects of the present invention can be more effectively exhibited.

  The content of the acidic reagent in the formaldehyde scavenger of the present invention is preferably 10 to 60 mol%, more preferably 20 to 40 mol%, still more preferably 30 to 40 mol% with respect to the supported urea. When nitric acid is used as the acidic reagent, the content thereof is preferably 20 to 100 mg, more preferably 20 to 70 mg, and still more preferably 30 to 60 mg, with respect to 1 g of the porous carbon material.

<Supporting method>
As a method for supporting (attaching) a supporting reagent such as urea or an acidic reagent on the porous carbon material, a method of immersing the porous carbon material in a solution (supporting reagent solution) in which the supporting reagent is dissolved, or a supporting reagent solution can be used. Examples include a method of spraying on a porous carbon material. The dipping method is preferred because the supported reagent can be uniformly and sufficiently supported on the inner walls of the pores of the porous carbon material. The immersion time is not particularly limited as long as a desired amount can be supported, and is, for example, about 1 to 72 hours, and preferably about 6 to 24 hours. When both urea and acidic reagent are used, they may be supported separately using separate solutions, or may be supported at once using a solution in which both are dissolved.

  The solvent for preparing the solution is not particularly limited as long as urea and an acidic reagent can be dissolved, and examples thereof include water and water-soluble organic solvents. From the viewpoint of safety and the like, water and hydrous ethanol are preferable.

  Here, the urea concentration of the supported reagent solution is preferably 0.1 to 20 w / v%, more preferably 1 to 10 w / v%, further preferably 1 to 5 w / v%, and 1 to 3 w / v%. Particularly preferred. Moreover, as an acidic reagent density | concentration, 0.1-10 v / v% is preferable, 0.3-8 v / v% is more preferable, 0.5-5 v / v% is further more preferable, 0.5-3 v / v % Is particularly preferred.

  In the formaldehyde scavenger of the present invention, the breakthrough time is preferably 5 hours or more, more preferably 7 hours or more, and more preferably 10 hours or more under the conditions of the example of relative humidity 40%. More preferably, it is particularly preferably 30 hours or more.

  Examples of the present invention are shown below, but the scope of the present invention is not limited thereto.

1. Preparation of formaldehyde scavenger (sample) <Preparation of porous carbon material>
As the porous carbon material, OG5A and OG15A (both manufactured by Osaka Gas Chemical Co., Ltd.), which are coal pitch ACFs having different activation treatments, were used. Specifically, OG5A fired at 300 ° C. for 1 hour and 800 ° C. for 1 hour under a nitrogen gas stream (OG5A-H300, OG5A-H800), and OG15A fired at 1100 ° C. for 1 hour (OG15A- H1100) was prepared.
In addition, S1600 (manufactured by STACF (Shanghai, China)) which is a cellulosic ACF was used as the porous carbon material. Specifically, S1600 baked at 1100 ° C. for 1 hour under a nitrogen gas stream (S1600-H1100) was prepared.

<Preparation of supported reagent solution>
As a supported reagent solution, a urea aqueous solution having a predetermined concentration (w / v%) and a mixed aqueous solution of urea having a predetermined concentration (w / v%) and nitric acid having a predetermined concentration (v / v%) were prepared.

<Preparation of formaldehyde scavenger>
The prepared ACF was immersed in each supported reagent solution for 24 hours, and the ACF was impregnated with the supported reagent. After impregnation, filtration was performed, and further, drying was performed under reduced pressure at 75 ° C. for 24 hours to obtain a target formaldehyde scavenger (sample).
Hereinafter, for example, OG5A-H300 prepared with a urea 1 w / v% solution is referred to as OG5A-H300 (urea 1%), and OG5A-H300 prepared with a mixed solution of urea 1 w / v% and nitric acid 2 v / v%. Is referred to as OG5A-H300 (1% urea + 2% nitric acid).

2. Test <Indoor formaldehyde ventilation test>
(Test method)
An indoor formaldehyde aeration test was conducted as follows.
Each sample was filled in an amount of 0.05 g in a glass tube having an inner diameter of 8 mm, and the relative humidity (RH) was 0% in a dry gas condition (no bubbling water passage) and 40% in a humidified gas situation (bubbling water passage). 10 ppm formaldehyde containing 21% oxygen was bubbled through the sample in the glass tube at 100 ml / min (FIG. 1). The concentration of formaldehyde after aeration of the sample was measured with a detector tube (manufactured by Gastec Corporation, No. 91L, No. 92L).

(result)
[Relative humidity (RH) 0%]
FIG. 2 shows the results of a formaldehyde aeration test conducted at RH 0% for OG15A-H1100 (urea 1%), OG15A-H1100 (urea 2%), OG15A-H1100 (urea 5%), and OG15A-H1100 (urea 10%). Shown in

  As shown in FIG. 2, as the concentration of the urea aqueous solution increases to 1, 2, 5 w / v%, the time from the ventilation to the breakthrough start (breakthrough start time) becomes longer, and the capturing ability is improved. At 10 w / v%, the breakthrough start time was shorter than that of 1 w / v%. When the concentration of the aqueous urea solution is 10 w / v%, the breakthrough start time is shortened, as shown in FIG. 3, while formaldehyde is trapped by urea supported in the pores of the porous carbon material (in FIG. 3). (A)) It is considered that part of the pores are blocked with urea ((b) in FIG. 3). Therefore, the amount of urea supported is preferably determined in consideration of the size of the pores of the porous carbon material.

  As comparative examples, (1) synthetic zeolite (HS-320: manufactured by Fujifilm) (unsupported), (2) synthetic zeolite (urea 2%), (3) OG15A (unsupported), (4) OG15A-H1100 (Unsupported) (6) Quartz wool (urea 2%) was also tested in the same manner. The result is shown in FIG. In addition, the result of (5) OG15A-H1100 (urea 2%) according to the example is also shown.

  As shown in FIG. 4, (1) synthetic zeolite (unsupported) and (2) synthetic zeolite (urea 2%) slightly trapped formaldehyde, but both had a breakthrough start time of 0 hours. It was found that there was almost no trapping capability even when urea was supported on zeolite with fine pores. In addition, about the thing which carry | supported urea and nitric acid on the synthetic zeolite, the breakthrough start time was 0 hour similarly (not shown).

In addition, (3) OG15A (unsupported) and (4) OG15A-H1100 (unsupported) also slightly captured formaldehyde, but both had a very short breakthrough start time of about 10 minutes.
(6) Quartz wool (urea 2%) could not capture (remove) formaldehyde at all.

  Next, FIG. 5 shows the results of a formaldehyde aeration test conducted at RH 0% for (3) OG15A-H1100 (urea 2% + nitric acid 1%) and (4) OG15A-H1100 (urea 3% + nitric acid 1%). Show. In addition, the results of (1) OG15A-H1100 (unsupported) as a comparative example and (2) OG15A-H1100 (urea 2%) as a reference example (positive control) are also shown.

  As shown in FIG. 5, (3) OG15A-H1100 (2% urea + 1% nitric acid) supporting nitric acid in addition to urea has a scavenging effect that lasts for 24 hours. (2) OG15A-H1100 ( The scavenging effect lasted more than 16.6 hours of urea (2%). Furthermore, (4) OG15A-H1100 (urea 3% + nitric acid 1%) has a scavenging effect that lasts for 39 hours, compared to (3) OG15A-H1100 (urea 2% + nitric acid 1%) for 24 hours. Furthermore, the capture effect was sustained.

  Next, FIG. 6 shows the results of a formaldehyde aeration test conducted at 0% RH on S1600-H1100 (urea 3% + nitric acid 1%) which is a cellulose ACF instead of the pitch ACF. In addition, the results of pitch-based OG15A-H1100 (urea 3% + nitric acid 1%) are shown.

  As shown in FIG. 6, it is understood that formaldehyde can be captured over a long period of time in the cellulose ACF as well as in the case of using the pitch ACF as the porous carbon material.

[Relative humidity (RH) 40%]
FIG. 7 shows the results of a formaldehyde aeration test conducted at RH 40% for OG15A-H1100 (urea 2%). The results for RH 0% are also shown.

  As shown in FIG. 7, OG15A-H1100 (urea 2%) had a long breakthrough time of 10 hours even at RH 40%, and was able to capture formaldehyde for a long time.

  FIG. 8 shows the results of a formaldehyde aeration test conducted at RH 40% for OG15A-H1100 (urea 2% + nitric acid 3%). The results for RH 0% are also shown.

  As shown in FIG. 8, OG15A-H1100 (urea 2% + nitric acid 3%) had a breakthrough time of 17 hours under the condition of RH 40%. Usually, the capture rate decreased due to the influence of humidity, and the breakthrough time was shortened, but the breakthrough time was longer than when RH was 0% (12 hours), and an unexpected result was obtained.

  At present, there is almost no material that can sufficiently capture formaldehyde under daily humidity conditions, but the formaldehyde capturing material of the present invention can sufficiently capture formaldehyde under daily humidity conditions. Expected to be put to practical use in filters.

The formaldehyde scavenger of the present invention is industrially useful because it can adsorb formaldehyde, which is one of highly harmful allergens.

Claims (4)

A formaldehyde scavenger in which urea and nitric acid are supported mainly on the pore inner walls of fibrous activated carbon calcined under an inert gas,
A formaldehyde scavenger, wherein 50 to 200 mg of urea is supported on 1 g of fibrous activated carbon and 20 to 70 mg of nitric acid is supported on 1 g of fibrous activated carbon. An air filter comprising the formaldehyde scavenger according to claim 1 .   The fibrous activated carbon calcined under an inert gas is immersed in a mixed solution having a urea concentration of 1 to 10 w / v% and a nitric acid concentration of 0.3 to 8 v / v%, filtered, dried, and then the fibrous A method for producing a formaldehyde scavenger, characterized in that urea and nitric acid are supported on the inner wall of pores of activated carbon. Method for manufacturing a formaldehyde scavenger material according to claim 3, wherein the producing formaldehyde scavenger material according to claim 1, wherein.