Compositions – Absorptive – or bindive – and chemically yieldive
Reexamination Certificate
2000-06-19
2003-04-01
Anthony, Joseph D. (Department: 1714)
Compositions
Absorptive, or bindive, and chemically yieldive
C252S181100, C252S181300, C252S190000
Reexamination Certificate
active
06540936
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an aldehyde gas absorbent and a process for absorbing an aldehyde gas.
The process according to the present invention pertains to a process for adding an aldehyde gas absorbent to fiber, paper, a molding resin or a coating composition, thereby imparting thereto aldehyde gas absorbing power.
2. Description of the Related Art
In recent years, there is a rapidly increasing demand for deodorization. Among offensive odors to be deodorized, that of cigarettes have been regarded as a particularly serious problem. The odor of cigarettes is mainly composed of acetaldehyde, nicotine, pyridine and acetic acid gas.
There has been an attempt to impart deodorizing properties to various furnishings such as curtains, wall paper and the like for a house, hospital or the like and to fiber utilized for the air conditioner of an automobile, filter of electric appliances, clothes or the like.
It has been known that amine compounds have high affinity with an aldehyde gas so that an aldehyde gas in an exhaust gas can be removed by bringing the aldehyde-gas-containing exhaust gas into contact with a solution having an amine compound dissolved therein (JP-A-51-44587 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”). The amine compound in the liquid form is however not suitable for use in the daily necessaries.
A gas absorbent having an amine compound carried on a heat resistant inorganic substance has been known and it is resistant to heating treatment suffered upon addition of it to a resin, paper or a film.
For example, known are a gas absorbent having an ammonium salt, aniline or the like carried on activated carbon (JP-A-53-29292, JP-A-56-53744); an absorbent having a compound, which contains in a molecule thereof a primary amino group, carried on a magnesium silicate clay mineral (JP-A-9-28778); and an absorbent having a polyamine compound carried between layers of a layered phosphate (&agr;-zirconium phosphate) (Tsubafuru, et al., PHARM. TECH. JAPAN, 12, 12, 77-87(1996)).
In addition, known are a carbon dioxide gas absorbent having an amino alcohol carried on silica (JP-B-53-23899); a deodorizer having a polyallylamine carried on silica (JP-B-63-141642); and a carbon dioxide gas absorbent having both water and an amine compound, which has a molecular weight per N atom of 110 or less and a boiling point of at least 100° C., carried on silica gel (JP-B-4-200742). However, it is hardly considered that these gas absorbents have aldehyde gas-absorbing power sufficiently satisfying requirements at an industrially level.
The gas absorbent employing activated carbon as a carrier is not usable in the sanitation-related fields because coloring occurs when it is kneaded into a resin or fiber.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an aldehyde gas absorbent which has a specific polyamine compound carried on a specific porous silicon dioxide to have an improved aldehyde gas-absorbing power.
Another object of the present invention is to provide a process for absorbing an aldehyde gas using the aldehyde gas absorbent.
A still other object of the present invention is to provide an aldehyde gas absorbing article comprising the aldehyde gas absorbent.
Other objects and effects of the invention will become more apparent from the following description.
The above-described objects of the present invention have been achieved by providing the following absorbent, process and article:
An aldehyde gas absorbent comprising:
a porous silicon dioxide having a specific surface area of from 400 to 900 m
2
/g and an average pore size of from 0.1 to 10 nm; and
a polyamine compound carried on the porous silicon dioxide in an amount of from 0.02 to 2.0 mmol/g, said polyamine compound being represented by the following formula:
H
2
N—(CH
2
CH
2
—NH)
n
—CH
2
CH
2
NH
2
wherein n stands for an integer of from 0 to 3;
A process for absorbing an aldehyde gas, which comprises incorporating an aldehyde gas absorbent as defined above in a medium; and
An aldehyde gas-absorbing article comprising a medium and an aldehyde gas absorbent as defined above.
DETAILED DESCRIPTION OF THE INVENTION
The aldehyde gas absorbent (which will hereinafter be abbreviated as “absorbent”) according to the present invention has a polyamine compound carried on the specific silicon dioxide described below. The amount of the polyamine compound carried on the silicon dioxide is 0.02 to 2 mmol, preferably from 0.2 to 1.1 mmol, per gram of the absorbent. When the amount is too small, the aldehyde gas absorbing power lowers. When the amount is too large, on the other hand, not only the polyamine compound becomes a cause for coloration, coming out from the silicon oxide by heating upon kneading with a resin or fiber but also the polyamine compound itself becomes an offensive odor, which reduces the absorption amount of an aldehyde gas. The amount of the polyamine compound carried on the silicon dioxide can be easily calculated from the nitrogen content detected by organic element analysis.
The absorbent according to the present invention preferably has an elution amount of the polyamine compound in terms of a nitrogen concentration, as measured by the following testing method, of 1 ppm or less.
(Testing Method)
In a polyethylene bottle, 1 g of a sample and 100 ml of pure water are charged, followed by shaking at 40° C. for 60 hours. The contents in the polyethylene bottle are filtered and the nitrogen concentration of the filtrate is measured.
The absorbent having less elution amount of a polyamine compound is excellent in the aldehyde gas absorbing power and heat discoloration resistance.
The absorbent according to the present invention is usually obtained in powdery form and it preferably has an average particle size of from 0.01 to 50 &mgr;m, more preferably from 0.1 to 20 &mgr;m, still more preferably from 0.1 to 5 &mgr;m. Absorbents having an average particle size less than 0.01 &mgr;m are not preferred, because it is accompanied with such problems as difficulty in handling and tendency to re-coagulation. Absorbents having an average particle size greater than 50 &mgr;m, on the other hand, are not preferred, because it is accompanied with such problems as difficulty in uniform dispersion in a resin and occurrence of yarn breakage upon spinning.
The absorbent of the present invention is effective for the absorption of an aldehyde gas. Examples of the aldehyde gas include acetaldehyde, formaldehyde, nonenal, crotonaldehyde and aryl aldehydes.
Silicon Dioxide
The silicon dioxide for use in the present invention is a porous silicon dioxide having a specific surface area of from 400 to 900 m
2
/g and an average pore size of from 0.1 to 10 nm. It preferably has a specific surface area of from 500 to 900 m
2
/g and an average pore size of from 2 to 8 nm.
Excessively small specific surface areas reduce the contact area of the polyamine compound with an aldehyde gas, thereby decreasing the gas absorption amount. Excessively large specific surface areas, on the other hand, tend to cause heat discoloration upon addition and kneading of a resin. The specific surface area can easily be determined by calculating the nitrogen absorption amount in accordance with the BET method.
Excessively large average pore sizes of the porous silicon dioxide bring about a reduction in the specific surface area, which lowers the amount of the polyamine compound carried thereon, thereby deteriorating the aldehyde gas absorption capacity. When the specific surface area is adjusted to a satisfactory size in spite of a too large average pore size, the void in the porous body becomes excessively large, which causes a deterioration in the mechanical strength or lowers the carrying capacity of the polyamine compound, resulting in the problem that the silicon dioxide inevitably releases the polyamine compound even by slight heating. When the average pore size is too small, on the other hand, the specific surface area of the silicon dioxide incr
Hirukawa Toshio
Takagi Osamu
Yamamoto Noriyuki
Anthony Joseph D.
Toagosei Co. Ltd.
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