JP7450874B2 - Formaldehyde gas scavenger - Google Patents

Description

The present invention relates to a formaldehyde gas scavenger that can capture formaldehyde gas in the air.

As indoor environments have become more airtight in recent years, it is known that various chemical substances are liberated from furniture, building materials, housing materials, wallpaper cloth, etc., even at low concentrations. Among them, formaldehyde is particularly widely used as an adhesive because it is inexpensive and easy to use.
On the other hand, formaldehyde is strictly regulated under the Industrial Safety and Health Act to be kept at extremely low levels in the work environment due to concerns about its negative effects on health. Furthermore, it is a regulated substance under the Building Sanitation Act in homes and offices.
Against this background, due to recent technological advances, the environment in buildings related to formaldehyde has been significantly improved by using non-formaldehyde or low-formaldehyde materials and installing appropriate ventilation equipment. In the home environment, there are still cases where incidental formaldehyde emitted from various sources using formaldehyde-containing adhesives becomes airborne formaldehyde and causes allergic symptoms in humans.
Therefore, various techniques have been devised and put into practical use to reduce the amount of formaldehyde released from the sources.
For example, Patent Document 1 discloses that a formaldehyde scavenger containing ethylene urea and ammonium salt is added to plywood as a powder or applied in a liquid state, thereby adsorbing formaldehyde generated from the plywood and dissipating it into the air. Techniques for suppressing the amount have been disclosed.
Patent Document 2 discloses a technique using an aqueous sulfanilic acid solution or an alcohol solution as a formaldehyde scavenger. When capturing formaldehyde in the air, it is said to be used by drying it and then supporting it on a solid substance.
Patent Document 3 discloses a technique using a carbodiimide compound as a formaldehyde scavenger.
Patent Document 4 discloses that a specific amine compound is effective in capturing formaldehyde floating in the air.
Many other formaldehyde trapping techniques have been disclosed, but some of them are not sufficiently effective or the trapping agents are expensive, so there is a need for a more effective formaldehyde trapping agent. It is.
Formalin is widely used for medical-related preservation work, inspection work, transport work, etc., such as moving and preserving corpses, moving and preserving organs, and inspecting and disinfecting organs. Further, since many fungi and bacteria are killed by formalin, diluted aqueous solutions are used for disinfection. However, formalin, which is an aqueous solution of formaldehyde, is colorless and transparent, has a pungent odor, and is harmful to living organisms. However, when the lid of the container containing formalin is opened during each of the above operations, it is inevitable that a considerably high concentration of formaldehyde will be scattered into the air.
It is quite difficult to efficiently capture formaldehyde once released into the air in this way, and currently there is no effective scavenger.

Japanese Patent Application Publication No. 2013-173814 Japanese Patent Application Publication No. 2013-94606 Japanese Patent Application Publication No. 2011-84563 Special Publication No. 2012-509100

The aim is to develop a new technology to remove airborne formaldehyde gas.

In order to solve the above problems, the present inventor conducted intensive studies and found that polyvinylamine crosslinked polymer particles can extremely effectively and quickly adsorb and capture formaldehyde gas in the air, leading to the present invention. The present invention will be explained in detail below.

Unlike many prior art scavengers, which include, for example, incorporation during wood composite and textile manufacturing processes (e.g., incorporation into formaldehyde-based resins), the polyvinylamine cross-linked polymer of the present invention A formaldehyde scavenger containing coalesced particles can capture formaldehyde in the air through a direct chemical reaction with formaldehyde. As such, it is essentially irreversible under ambient conditions of temperature and pressure and is therefore a highly effective method of isolating formaldehyde from re-emission.

Formaldehyde gas scavengers containing polyvinylamine crosslinked polymer particles in the present invention are used to scavenge airborne formaldehyde from the environment or space surrounding formaldehyde emitting articles.
The scavenger can be used in a variety of forms, depending on the particular application, for example. It can be dispersed loosely in trays, or it can be placed in a gas permeable container or cartridge in a formaldehyde-contaminated environment.
It can also be used, for example, in paper pouches of the type used to package silica gel and calcium oxide, which are commonly included in dehumidifying packaging products.
Furthermore, it can also be used as a formaldehyde gas absorption filter by supporting (holding) it on a nonwoven fabric sheet made of synthetic fibers or natural fibers, or a mesh member made of metal, plastic, or the like. A formaldehyde gas adsorption filter in which the present scavenger is supported on a nonwoven fabric is particularly effective. There are no particular limitations on the method of supporting the material, and examples include a method of coating with a binder, a method of supporting the material by sandwiching it between a plurality of sheets, and the like.

There are no particular restrictions on where it can be used, but it can be used in homes, offices, and sites where formalin is used, as well as warehouses, wood composite and textile production facilities where formaldehyde resin is used, attics, and air treatment systems where there is continuous air flow. Suitable for use where the airflow is concentrated near the airflow, air ducts, or inlet or outlet of a heating/cooling device.
For the effectiveness of the formaldehyde scavenger in the present invention, there is no need to actively circulate air around the compound. In fact, the formaldehyde scavenger is preferably used to remove formaldehyde passively (ie without mechanical air circulation) from the surrounding environment.

Hereinafter, the method for producing polyvinylamine crosslinked polymer particles in the present invention will be explained.

As a method for producing polyvinylamine crosslinked polymer particles in the present invention, suspension polymerization, which is generally used, is first applied. That is, N-vinylcarboxylic acid amide, a polyvinyl compound, a monomer copolymerizable with N-vinylcarboxylic acid amide, a polymerization initiator, and a cationic polymer dispersant are suspended in salt water, and any desired It can be produced by stirring vigorously to generate monomer droplets and carrying out radical polymerization. The particle size of the monomer droplets is controlled by the dispersant and stirring intensity, but is 0.01 mm to 10 mm, preferably 0.1 mm to 5 mm.

Examples of N-vinylcarboxylic acid amide monomers used in the present invention include N-vinylformamide, N-methyl-N-vinylformamide, N-vinylacetamide, N-methyl-N-vinylacetamide, and N-vinylpropion. amide, N-methyl-N-vinylpropionamide, N-vinylbutyramide, N-vinylisobutyramide and the like, with N-vinylformamide being preferred. In addition to N-vinylcarboxylic acid amide monomers, monomers that can be copolymerized with N-vinylcarboxylic acid amide may be used, such as (meth)acrylonitrile, (meth)acrylamide, N-alkyl (meth)acrylamide, N, N'-dialkyl (meth)acrylamide, N,N'-dialkylaminoalkyl (meth)acrylamide, alkali metal salt or ammonium salt of (meth)acrylamide alkanesulfonic acid, alkali metal salt or ammonium salt of (meth)acrylic acid, Hydroxyalkyl (meth)acrylate, dialkylaminoalkyl (meth)acrylate, (meth)acryloyloxyalkyltrimethylammonium salt, alkali metal salt or ammonium salt of (meth)acryloyloxyalkanesulfonic acid, N-vinylpyrrolidone, diallyldialkylammonium salt , vinylpyridine, vinylimidazole, vinylbenzyl trialkylammonium salts, alkali metal salts or ammonium salts of vinylsulfonic acid, etc., and one type of these may be used, or two or more types may be used in combination. Acrylonitrile is particularly preferred.

Examples of polyvinyl compounds include aromatic polyvinyl compounds such as divinylbenzene, trivinylbenzene, and divinyltoluene, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, glycerol di(meth)acrylate, and trimethylolpropane tri(meth)acrylate. Poly(meth)acrylates such as acrylates, methylenebisacrylamide, etc. can also be used. Preference is given to using aromatic divinyl compounds. Most preferred is divinylbenzene. The addition rate is in the range of 0.1 to 50% by mass, preferably 0.1 to 20% by mass, based on the monomer. If the amount exceeds 5% by mass, it becomes difficult to obtain spherical particles using only N-vinylcarboxylic acid amide, so it is preferable to use a monomer that can be copolymerized with N-vinylcarboxylic acid amide. The addition rate of the copolymerizable monomer is 50% by mass or less based on the total monomers. Particular preference is given to using acrylonitrile.

Examples of polymerization initiators include azo-based and peroxide-based polymerization initiators, such as 2,2'-azobis(2,4-dimethylvaleronitrile) and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile). nitrile), 2,2'-azobis(2-methylpropionitrile), 2,2'-azobis-2-amidinopropane hydrochloride, 4,4'-azobis-4-cyanovaleric acid, 2,2'-azobis [2-(5-methyl-imidazolin-2-yl)propane] hydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] hydrochloride, ammonium or potassium peroxodisulfate, Examples include hydrogen oxide, benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, succinic peroxide, t-butyl peroxy-2-ethylhexanoate, and the like. Among these, oil-soluble initiators such as 2,2'-azobis(2,4-dimethylvaleronitrile) and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) are preferred. Furthermore, two or more types of initiators may be used in combination. The addition rate is usually 0.02 to 5% by weight, preferably 0.05 to 2% by weight based on the monomer.

Cationic polymer dispersants are polymerized cationic monomers such as (meth)acryloyloxyethyltrimethylammonium chloride and dimethyldiallylammonium chloride. Copolymers can also be used. Examples of nonionic monomers include acrylamide, N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone, N,N'-dimethylacrylamide, acrylonitrile, diacetone acrylamide, 2-hydroxyethyl (meth)acrylate, etc. Can be mentioned. The weight average molecular weight of the cationic polymer dispersant is 5,000 to 2,000,000, preferably 50,000 to 1,000,000. The addition rate is usually 0.05 to 5% by weight, preferably 0.1 to 2% by weight based on water.

Examples of the salt include ammonium sulfate, sodium sulfate, ammonium chloride, sodium chloride, calcium chloride, etc. Among these, ammonium sulfate is particularly preferred. Further, these materials may be used alone or in combination. The addition rate is in the range of 30 to 100% by mass based on water; if it is less than 30% by mass, the N-vinylcarboxylic acid amide is insufficiently separated into two phases, and at 100% by mass, the effect of the salt cannot be sufficiently obtained. Therefore, it is uneconomical to add more than 100% by mass. It is preferably 50 to 90% by weight, more preferably 60 to 90% by weight.

The polyvinylamine crosslinked polymer particles in the present invention preferably have a porous structure in order to increase the contact area with formaldehyde gas as much as possible.
In order to obtain polyvinylamine crosslinked polymer particles having a porous structure, an organic solvent is used during suspension polymerization. Examples of organic solvents used include alcohols such as 1-propanol, 2-propanol, 1-butanol, 2-butanol, and tert-butanol, esters such as methyl acetate, ethyl acetate, and propyl acetate, methyl ethyl ketone, and methyl isobutyl ketone. In addition to ethers such as ketones and ethylene glycol dimethyl ether, organic solvents having polar groups such as butoxyethanol and ethoxyethanol can be used. These organic solvents are somewhat soluble in water, but by using high concentrations of salt they can be partitioned into the monomer phase. The amount of these organic solvents added is 5 to 200% by weight, preferably 10 to 100% by weight based on the total monomers.

The polymerization reaction is usually carried out at a temperature of 30° C. to 100° C. for a period of 1 hour to 15 hours.
After polymerization, salts, cationic polymer dispersants, organic solvents, unreacted monomers, etc. can be removed by washing with water. Further, the remaining organic solvent can also be removed by distillation or the like.

Polyvinylcarboxylic acid amide crosslinked polymer particles are obtained by the above manufacturing method. Thereafter, polyvinylamine crosslinked polymer particles can be obtained by hydrolysis. Hydrolysis can be carried out under either basic or acidic conditions.
The base suitable for hydrolysis is not limited as long as it can maintain a pH in the range of 8 to 14 during hydrolysis, and it is most preferable to use an aqueous solution of sodium hydroxide, potassium hydroxide, or ammonia. The addition rate is preferably 0.05 to 2.0 equivalents, more preferably 0.4 to 1.2 equivalents based on the formyl group of the polymer.

Suitable acids for hydrolysis are not limited as long as the pH can be adjusted to a range of 0 to 5 during hydrolysis, and include inorganic acids such as hydrohalic acid, sulfuric acid, nitric acid, and phosphoric acid, and acids with a carbon number of 1. Examples include organic acids such as mono- and dicarboxylic acids, sulfonic acid, benzenesulfonic acid, and toluenesulfonic acid in the range of 5 to 5, and it is particularly preferable to use hydrohalic acid and hydrogen halide gas, and use hydrohalic acid. is most preferable. The addition rate is preferably 0.05 to 2.0 equivalents, more preferably 0.4 to 1.2 equivalents based on the formyl group of the polymer.

After hydrolysis, polyvinylamine crosslinked polymer particles can be obtained by washing with water or the like.

The polyvinylamine crosslinked polymer particles in the present invention are spherical particles with a particle size in the range of 10 μm to 2 mm. Specific surface area is used as an index of porous structure. In the present invention, if the specific surface area is 1.0 m ² /g or more, it can be said that the material has a porous structure. Crosslinked polymer particles without a porous structure have a value of 0 m ² /g or close to 0 m ² /g. The specific surface area can be determined by the BET method. For example, after drying the crosslinked polymer spherical particles in vacuum, it can be determined by the BET one-point method using Quantachrome ChemBET3000 (manufactured by Quantachrome) using 30% nitrogen + helium.

The production examples of polyvinylamine crosslinked polymer particles according to the present invention and their effects as formaldehyde gas scavengers will be specifically explained below, but the present invention is not limited to the following examples.

(Manufacturing example 1)
216.0 g of demineralized water, 144.1 g of ammonium sulfate, and 9.1 g of an aqueous solution of polyacryloyloxyethyltrimethylammonium chloride (polymer concentration 20% by mass, weight average molecular weight 800,000) were placed in a 500 mL four-necked flask and stirred. The mixture was dissolved and used as a polymerization bath. 33.0 g of N-vinylformamide, 15.0 g of 80% divinylbenzene, 12.1 g of acrylonitrile, 60.1 g of ethyl acetate, azo polymerization initiator 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) ) (V-70, manufactured by Wako Pure Chemical Industries, Ltd.) (0.6 g) was mixed to prepare a monomer solution. The monomer solution and the polymerization bath were mixed and stirred at 150 rpm while purging the inside of the flask with nitrogen. After 30 minutes, the temperature was raised and polymerization was carried out at 50°C for 3 hours and then at 60°C for 1 hour. After polymerization, the polymer was filtered, washed with water, and filtered to obtain 148.1 g of polymer spherical particles in a water-containing state and free of aggregates.
35.0 g of the reaction product thus obtained was placed in a four-necked flask, 50.7 g of a 48% by mass aqueous sodium hydroxide solution and 50.1 g of water were added, and the mixture was hydrolyzed at 80° C. for 5 hours with stirring. . The mixture was washed with water and filtered to obtain 32.8 g of water-containing polyvinylamine spherical particles. As a result of microscopic observation, spherical particles of 50 μm to 1 mm were observed. After vacuum drying, the specific surface area of the white spherical particles was measured to be 14 m ² /g, indicating that they had a porous structure. The polyvinylamine crosslinked polymer particles thus obtained are referred to as sample A.

(Manufacturing example 2)
217.1 g of demineralized water, 144.0 g of ammonium sulfate, and 9.0 g of an aqueous polyacryloyloxyethyltrimethylammonium chloride solution (polymer concentration 20% by mass, weight average molecular weight 800,000) were placed in a 500 mL four-necked flask, and stirred. The mixture was dissolved and used as a polymerization bath. N-vinylformamide 49.8g, 80% divinylbenzene 4.2g, acrylonitrile 6.0g, azo polymerization initiator 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) (V-70, (manufactured by Wako Pure Chemical Industries, Ltd.) was mixed to prepare a monomer solution. The monomer solution and the polymerization bath were mixed and stirred at 140 rpm while purging the inside of the flask with nitrogen. After 30 minutes, the temperature was raised and polymerization was carried out at 50°C for 3 hours and then at 60°C for 1 hour. After polymerization, the mixture was filtered, washed with water, and filtered to obtain 118.3 g of water-containing polymer spherical particles.
105 g of the reaction product thus obtained was placed in a four-necked flask, 150.1 g of a 48% by mass aqueous sodium hydroxide solution and 150.1 g of demineralized water were added, and the mixture was hydrolyzed at 80° C. for 5 hours with stirring. The mixture was washed with water and filtered to obtain 112.1 g of water-containing polyvinylamine spherical particles. As a result of microscopic observation, spherical particles of 50 μm to 2 mm were observed. After vacuum drying, the specific surface area of the white spherical particles was measured and found to be less than 1 m ² /g. The polyvinylamine crosslinked polymer particles thus obtained are referred to as Sample B.

(Example 1)
An odor sampling bag [capacity 5 L, Tedlar bag (manufactured by As One Corporation)] containing Sample A prepared in Production Example 1 was defined as a "test measurement", and a bag without Sample A was defined as a "blank". A bag was filled with 1.5 L of the prepared odor component, and the odor concentration was measured using a detection tube after standing for 15 minutes, 30 minutes, and 60 minutes. Each sample was measured three times, and the average value is shown in Table 1.

(Table 1)

( Comparative example 1 )
The test was conducted in the same manner as in Example 1, except that Sample B was used instead of Sample A in Example 1. The results are shown in Table 2.

(Table 2)

As is clear from the test results in Tables 1 and 2, it can be seen that the polyvinylamine crosslinked polymer particles according to the present invention have very good formaldehyde trapping ability. In particular, sample A of polyvinylamine crosslinked polymer particles having a porous structure has a high collection rate and is found to have an extremely remarkable formaldehyde collection ability.

Claims (2)

N-vinylcarboxylic acid amide, polyvinyl compound, monomer copolymerizable with N-vinylcarboxylic acid amide, organic solvent, polymerization initiator, and cationic polymer dispersant are suspended in salt water and stirred at arbitrary strength. Polyvinylamine crosslinked polymer particles, which are spherical particles with a particle size in the range of 10 μm to 2 mm and have a specific surface area of 1.0 m ² /g or more , are produced by generating monomer droplets and performing radical polymerization. A method for producing a formaldehyde gas scavenger comprising: A method for producing a formaldehyde gas adsorption filter, in which a formaldehyde gas scavenger produced by the production method according to claim 1 is supported on a nonwoven fabric.