JPH07208777A - Humidifying method - Google Patents

Abstract

PURPOSE:To provide a humidifying method of long life in which a complex film comprised of hydrophilic urethane layer and hydrophobic porous layer is used as a humidifying film, thereby its price is less expensive, a high permeability of water vapor can be attained, a high humidifying volume is obtained through cleaning, its device setting can be easily carried out and further its operation cost can be made less-expensive. CONSTITUTION:A complex member film comprised of a hydrophilic urethane layer and a hydrophobic porous layer is used as a humidifying film. As a method for making a complex state of a porous base member and the hydrophilic urethane layer, the hydrophilic urethane resin is made into a film form, thereafter water is accumulated in the porous base member or hydrophilic urethane resin solution, suspended solution or emulsion polymerization latex or the like are immersed in the porous base member, dried is illustrated. Water is contacted with the hydrophilic urethane layer having a humidifying film obtained in this way and then air to be humidified is flowed at the side of the hydrophobic porous member. In this way, steam may pass through the film, the steam is discharged at an air side of the film and the humidifying operation is carried out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for permeating water vapor to humidify a gas in the case of maintaining constant humidity conditions for food production, storage, maintenance of precision machinery, computers and the like.

[0002]

2. Description of the Related Art Conventionally, as a method for humidifying air,
There are (1) vaporization method, (2) water spray method, and (3) humidification film method.

In the vaporization method (1), bacteria contained in water,
It is possible to perform clean humidification without removing impurities such as chlorine components, but it requires electric power to heat water and has the drawback that maintenance is complicated, such as frequent cleaning of evaporation residue. .

The water spray method of (2) has an advantage that it requires less power, but has a drawback that bacteria in water and chlorine components are scattered in the air.

The humidifying membrane method of (3) has the characteristic that clean humidified air can be obtained because it is humidified through a membrane that allows water vapor to pass through. However, it has a high water vapor permeability and durability, especially resistance to bacteria. It is not put to practical use because it has no mold-resistant film. That is, as a membrane having a large water vapor permeability, a natural polymer membrane such as a cellulosic membrane is known, but these membranes are liable to be decomposed by bacteria and mold in water and cannot be used for a long time.

There is also known a method of using a hydrophobic porous body which is impermeable to water but permeable to water vapor. This is a method of partitioning water and air through a hydrophobic porous body, allowing water vapor to pass through the porous body, and humidifying the air. However, the porous body gradually loses its hydrophobicity as it is used, becomes more hydrophilic, and finally allows water to permeate, so that it cannot be used for a long time in terms of durability.

Further, as a humidifying film that can be used for a long period of time, a humidifying film composed of a composite film of an ion exchange layer and a porous body having hydrophilicity has been proposed (JP-A-2-293551). However, since a polymer having an ion exchange group is used for the ion exchange layer of this composite membrane, it becomes relatively expensive and may be disadvantageous in terms of economy.

[0008]

SUMMARY OF THE INVENTION The present invention is intended to overcome the above-mentioned drawbacks of the prior art.
Provided is a humidification method which is inexpensive and has a high water vapor permeability.
More specifically, the present invention provides a long-life humidification method that is clean, has a large humidification capacity, can be easily made into a device, and can reduce operating costs.

[0009]

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention has conducted extensive studies, and as a result, used a composite film composed of a hydrophilic urethane layer and a hydrophobic porous material layer as a humidifying film. Found that the method of doing
The present invention has been completed.

The hydrophilic urethane layer used in the present invention is water vapor permeable, and the urethane is preferably made of diisocyanate and polyol. As the diisocyanate, tolylene diisocyanate,
4,4'-diphenylmethane diisocyanate, naphthalene-1,5-diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, 4,4 '
-Dicyclohexylmethane diisocyanate, isophorone diisocyanate, etc. are exemplified, among which 4,
4'-diphenylmethane diisocyanate and 4,4
'-Dicyclohexylmethane diisocyanate is particularly preferable because it imparts a skeleton excellent in mechanical properties and elastic properties.

As the polyol, polyether polyol, polyester polyol, polycarbonate polyol, polybutadiene polyol and the like can be used without limitation, but they have high water absorption and impart flexibility.
A polyether polyol having excellent molding processability is preferable. As the polyether polyol, polypropylene glycol, polyethylene glycol and polyhexyl glycol can be used, but polyethylene glycol is particularly preferable because it has excellent hydrophilicity. Polyethylene glycol having a molecular weight of 400 to 4,000 can be used, but 1,000 to 2,000 is particularly preferable.

On the other hand, the porous substrate used in the present invention has a pore size of 0.01 to 100 μm and a thickness of 10 to 500.
Those having a hydrophobicity of μm are preferable.

The porous substrate used in the present invention includes:
Those having durability such as dimensional stability against water and temperature, mechanical strength, chemical resistance, and mold resistance can be used without limitation, and preferable examples include polytetrafluoroethylene and tetrafluoroethylene-ethylene. Copolymers, fibers of fluoropolymers such as polyvinylidene fluoride, polyethylene,
Examples include olefin polymer fibers such as polypropylene, woven fabrics, non-woven fabrics and microporous bodies made of plant fibers and carbon fibers. As the shape, any shape that can partition the water side and the air side can be used, and examples thereof include a flat shape and a hollow shape.

The composite method of the porous substrate and the hydrophilic urethane layer may be a method in which the hydrophilic urethane resin is formed into a film and then laminated with the porous substrate, or a solution, suspension or emulsion polymerization latex of the hydrophilic urethane resin. Impregnated into a porous substrate
A method of drying is exemplified.

Water is brought into contact with the hydrophilic urethane layer side of the humidifying membrane thus obtained, and the air to be humidified is flown to the hydrophobic porous body side. Thus, the water vapor permeates the inside of the film, the water vapor is released on the air side of the film, and humidification can be performed. The driving force in this case is the water vapor partial pressure difference across the membrane. The water vapor partial pressure on the water side of the membrane is considered to correspond to the saturated water vapor pressure at that temperature.

The water may be replenished or flowed in an amount not less than that reduced by permeation. Also, the water used for humidification can be sufficiently clean even if it is tap water. Of course, water treated by a water treatment device such as a deionizer may be used.

Next, the present invention will be described with reference to examples.
The present invention is not limited to such embodiments.

[0018]

EXAMPLE After polymerizing 4,4'-diphenylmethane diisocyanate and polyethylene glycol having a molecular weight of 1,000, 40 parts of toluene and 50 parts of isopropanol were obtained.
Parts and 10 parts of dimethylformamide were dissolved in a mixed solvent to obtain a 30 wt% urethane solution. This solution was cast on a porous body having a pore size of 0.6 μm, a porosity of 85%, and a thickness of 20 μm, dried at 90 ° C., and comprised of a hydrophilic urethane layer adjusted to have a thickness of 80 μm on the porous body. A humidified composite membrane was obtained.

The obtained humidifying membrane is sandwiched between cells, the hydrophilic urethane layer side is filled with water, and the porous body side is flushed with nitrogen, and the water vapor permeability is calculated from the relative humidity at the cell inlet and the cell outlet, The results are shown in Table 1.

[0020]

[Table 1]

[0021]

Industrial Applicability A novel moisturizing membrane which is economical because it can maintain high performance for a long time and is made of a relatively inexpensive polymer material is provided.

Claims (3)

[Claims] 1. A humidifying gas is brought into contact with one surface of a humidifying membrane,
A method for humidifying a gas by bringing water into contact with the other surface, wherein the humidifying film is a composite film of a hydrophilic urethane layer and a hydrophobic porous material layer. 2. The urethane of the hydrophilic urethane layer is 4,4'-
Diphenylmethane diisocyanate or 4,4'-dicyclohexylmethane diisocyanate with a molecular weight of 40
The method of claim 1 comprising 0 to 4,000 polyethylene glycols. 3. The humidifying method according to claim 1, wherein the hydrophobic porous body layer is a hollow fiber-like porous body.