JPS61197020A - Moisture absorption material and its production - Google Patents

Abstract

PURPOSE:To obtain a moisture absorption material capable of being utilized as a vessel or a packaging material of the substance to be dried wherein calcium chloride does not fall off and the producing process is simple and the producing cost is inexpensive by housing calcium chloride to the inside of the foams of formed urethane with a moisture holding agent. CONSTITUTION:A foamed urethane sheet 2 is drawn out from a material roll 1 with the drawing rolls 3 and sent to a CaCl2 blowing zone 4 and CaCl2 pow der is fed to the nozzles 5 together with the high-pressure air and blown on the sheet 2. CaCl2 particles are inserted into the inside of the sheet 2 by sucking them with a suction pump 6 from the surface of the opposite side to the foamed urethane surface blown with CaCl2 powder. Then the sheet 2 is immersed in a bath 8 of a mixed soln. of both clay mineral such as bentonite and zeolite and a weak alkali soln. in an immersion zone 7 and heated to impregnate a moisture holding agent soln. into the inside of the air foams of the foamed urethane. After drying it in a drying zone 10, paste is coated on the surface of the sheet 2 to stick air-permeable films 15, 15' on both sides and a moisture absorption material is produced by punching it in the various shapes with a pressing machine 17.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a new and useful moisture absorbent and a method for producing the same.

[Conventional technology and its problems]

Moisture absorbing agents used to remove moisture from gaseous, liquid, and solid materials include silica gel, anhydrous calcium sulfate, and calcium chloride. The moisture absorbing agent is used to dehumidify products that contain moisture (for example, foods such as seaweed and confectionery, precision electronic parts such as ICs and LSIs) during the distribution process, to keep precision equipment dry, and to dehumidify household items such as cupboards. Powdered or granular hygroscopic agents are recommended in order to increase the surface area of the hygroscopic agent.

Conventionally, powdered or granular moisture absorbents have been used by being filled into air-permeable sachets and inserted into a container for the substance to be dried, or filled into an insole at the bottom of the container. Further, the powdered moisture absorbent is formed into a disk shape and is used by being stored in a storage section inside a container cap. However, the need for special space in the container or package for the moisture absorbent requires preparation of the container or package, which is laborious and costly.

On the other hand, there is a moisture-absorbing sheet in which the voids of an air-permeable porous sheet are filled with a powdery moisture-absorbing agent, and the filled sheet is used as a container or packaging material for a substance to be dried. However, since the powdered moisture absorbent is simply contained in the voids of the breathable porous sheet, nonwoven fabric must be laminated on both sides of the porous sheet to prevent the moisture absorbent from falling off. This leads to complicated processes and a rise in manufacturing costs.

An object of the present invention is to provide a moisture absorbent body that does not have the above-mentioned drawbacks and can be used as a container or packaging material for substances to be dried, as well as a method for producing the same.

[Means for solving problems]

As a result of various experimental studies, the present inventor unexpectedly discovered that chloride, which is a moisture absorbent, is present in the urethane foam due to the moisture retaining agent (for example, clay minerals such as bentonite or zeolite) used together with the moisture absorbent. The present inventors have discovered that accommodating calcium particles is effective in achieving the above objectives, and have completed the present invention.

That is, the moisture absorbent of the present invention is characterized in that calcium chloride particles are accommodated within the urethane foam by a moisture retaining agent, particularly at least one type of clay mineral.

Furthermore, the method for producing a moisture absorbent according to the present invention is characterized by comprising the following steps.

(b) A step of spraying powdered calcium chloride onto one side of the supplied urethane foam and simultaneously sucking air from the other side of the urethane foam to draw calcium chloride particles into the urethane foam (b) Urethane foam containing calcium chloride particles Step (c) of impregnating the urethane foam with the water-retaining agent solution by placing it in a water-retaining agent bath (c) Drying the urethane foam containing the water-retaining agent solution Calcium chloride used in the present invention is an anhydrous salt, -
It may be any of a hydrate salt, a dihydrate salt, and a σ hexahydrate salt, but an anhydrous salt or a dihydrate salt is preferable.

The dimensions of the calcium chloride particles can be changed as appropriate depending on the size of the urethane foam, the parameters of the manufacturing process (spraying speed, humidity and concentration of the impregnating liquid, etc.), the desired performance of the moisture absorbent, and the like. Examples of calcium chloride particle sizes include 1μ to 1
There is 000μ.

The foamed urethane in the present invention is a polyurethane resin made by reacting isocyanates with polyols (such as polyesters or polyethers having less than OH groups), extending the chain with urethane bonds, and making it three-dimensional. During the reaction, a small amount of blowing agent (water, Freon, etc.) is added, and the carbon dioxide generated by the reaction with isocyanate is used to form a foam. The mechanical properties, shape, number and size of foam, etc. of the urethane foam can be determined as appropriate depending on the use of the moisture absorbent. In the present invention, the foamed urethane acts as a carrier for calcium chloride particles as a moisture absorbent and a moisture retention agent, and the shape of the moisture absorbent of the present invention is determined by molding the urethane into a desired shape.

The moisture retaining agent in the present invention functions to retain the water absorbed by the moisture absorbent from the substance to be dried and to assist the performance of the moisture absorbing agent, and is, for example, a clay mineral or a porous material. . Suitable clay minerals include bentonite, zeolite, attabulgite, and the like.

The moisture absorbent of the present invention contains calcium chloride particles within foamed urethane foam using a moisture retaining agent.

In the present invention, the moisture retaining agent retains moisture from deliquesced calcium chloride to prevent leakage of water to the outside, and also contains calcium chloride particles in the foam so that the calcium chloride particles are released from the urethane foam. restrain from doing.

That is, the moisture retention agent traps the calcium chloride particles within the urethane foam. This containment by a moisture retaining agent can be embodied in a variety of ways, all of which achieve the objectives of the present invention. An example of such a mode is accommodation in which calcium chloride particles are fixed to the inner wall of a bubble via a moisture retaining agent. Furthermore, it is possible to prevent the internal calcium chloride particles from detaching by filling the bubbles of at least the surface phase portion of the urethane foam with a moisture retaining agent to the extent that air permeability is not impaired.

The method for producing the moisture absorbent of the present invention involves first spraying powdered calcium chloride onto one side of supplied urethane foam, and at the same time drawing in air from the other side of the urethane foam to draw calcium chloride particles into the foam of the urethane foam. Become. However, it is not necessary to introduce it into all the foam, but it is desirable to draw it into at least the center of the urethane foam. The speed and strength of calcium chloride spraying and suction can be appropriately determined depending on the thickness, air permeability, supply rate, etc. of the urethane foam.

The urethane foam containing the calcium chloride particles within the foam is then impregnated with a water retention agent solution. At that time, the urethane is impregnated from the surface to the inside.

The water retention agent solution is prepared in advance by dissolving or slurrying the water retention agent, such as bentonite or zeolite, in a slightly alkaline aqueous solution.

Impregnation of urethane foam can be carried out in various ways.
.

For example, the urethane foam can be immersed in a bath of a water retention agent solution, or the urethane foam can be sprayed with the water retention agent solution. Content of water retention agent solution
In order to am il, it is desirable to remove excess water retention agent solution after immersion or spraying in the baths described above.

The urethane foam containing the water retention agent solution is then transferred to a drying step. This drying must be carried out sufficiently to reach the inside of the urethane foam, but any drying method may be used. For example, drying can be performed using ventilation drying, infrared irradiation drying, vacuum drying, high frequency drying, hot air drying, or the like.

Dried urethane foam can be used as a moisture absorbent, but depending on the purpose, it can be processed by cutting, molding, packaging, and covering with plastic film, paper, nonwoven fabric, etc., or stored as a moisture absorbent material. It's okay.

Note that auxiliary agents such as insect repellents and rust preventive agents may be added together with the calcium chloride particles or with the moisture retaining agent.

(Function) Although it is not necessarily theoretically clear that the moisture absorbent of the present invention and the method for producing the same are believed to function mainly as follows.

Calcium chloride particles act as hygroscopic agents and thus reduce the humidity of the atmosphere. The water absorbed by calcium chloride deliquesces the calcium chloride, but the water retaining agent (such as bentonite, zeolite, etc.) surrounding the calcium chloride absorbs the water, preventing deterioration of the moisture absorption ability of the calcium chloride. can. In addition, the moisture retention agent confines calcium chloride particles within the urethane foam foam. This is because the moisture retaining agent adheres to the inner wall of the foam and the calcium chloride particles and retains the calcium chloride particles within the urethane foam, or because the moisture retaining agent adheres to the inner walls of the foam and the calcium chloride particles, or because the moisture retaining agent adheres to the inner wall of the foam and the calcium chloride particles and retains the calcium chloride particles within the urethane foam. This is thought to be because the particles are filled to the extent that they are prevented from detaching, or because a layer of moisture retaining agent grows around the calcium chloride particles and prevents the calcium chloride particles from coming out when removed. It will be done.

In the manufacturing method of the present invention, calcium chloride particles are drawn into the urethane foam and then impregnated with a water retention agent solution.

Through this and subsequent drying, the moisture retaining agent causes the calcium chloride particles to stick to the inner wall of the foam, or the moisture retaining agent fills the surface part of the urethane foam, or a layer of moisture retaining agent grows around the calcium chloride particles. This makes it easier to contain the calcium chloride particles within the foam.

〔Effect of the invention) The present invention provides the following effects.

(b) Calcium chloride particles, which are moisture absorbers, are trapped within the foam of urethane foam by the moisture retention agent, so
Calcium chloride particles do not leak out during use of the moisture absorbent of the present invention.

Therefore, it is not essential to attach a nonwoven fabric, a film, etc. to the outer surface of the moisture absorbent, and it is possible to provide a moisture absorbent that is easy to handle.

(Ll) In the moisture absorbent of the present invention, foamed urethane is used as a carrier for calcium chloride particles, so it is extremely easy to process and mold. The moisture absorber itself can be used as a packaging material.

(c) The production method of the present invention enables continuous production and does not require complicated equipment for each process itself, so the moisture absorbent of the present invention can be produced easily and inexpensively. .

[Example] The present invention will be described in detail by showing an example of an apparatus for continuously carrying out the method for producing a moisture absorbent according to the present invention.

FIG. 1 is a schematic diagram of an example of the device.

A sheet-shaped urethane foam material roll 1 slit into a sheet with a thickness of 3non to 5mm and a width of about 100 to 900mm.
From there, the foamed urethane sheet 2 is pulled out by a pull-out roller 3. The drawn urethane foam sheet 2 is sprayed with calcium chloride on the downstream side of the drawing roller 3 in a zone 4.
supplied to In this zone 4, calcium chloride particles are supplied from a powdered calcium chloride source (not shown) together with high pressure air to a nozzle 5 to spray the calcium chloride particles onto the foamed urethane sheet. Air is taken in by the suction pump 6 from the surface opposite to the sprayed urethane foam surface. At this time, calcium chloride particles are drawn into the foamed urethane sheet.

For calcium chloride spraying, an impregnating zone 7 is provided downstream of the zone 4. The foamed urethane sheet 2 supplied to the impregnation zone 7 is immersed in a bath 8 of a mixture of bentonite or zeolide and a weak alkaline liquid. The temperature of the bath 8 is preferably 30°C to 80°C, and this heating allows more of the water retention agent solution to permeate into the cells of the urethane foam. The squeezing roller 9 inside the bath 8 as well as the restoring force of the urethane foam impregnates the required and desired water retention agent solution into the foam of the urethane foam. Subsequently, the foamed urethane sheet is pulled out of the bath.

The sheet withdrawn from the bath is then introduced into a downstream drying zone 10. In this zone, a heater 11 is provided above the seat, and a blower 12 is provided further above. The sheet passing under the heater 11 is heated by the heater 11 and at the same time is blown by the blower 12 to dry the foamed urethane sheet.

In this example of the apparatus, glue is subsequently applied to the surface of the foamed urethane sheet from the synthetic glue supply source 13, and a breathable film 15 from the film supply roll 14 is adhered to one side of the sheet. Similarly, a film 15' is applied to the working surface of the sheet by a glue source 13' and a film supply roll 14'.

The urethane foam 16 with air-permeable films attached to both sides is punched into various shapes by the brace Ia 17 and used as a moisture absorbent.

The moisture absorbent of the present invention can be processed and molded for various uses. Figures 2 to 6 show examples of such moisture absorbers. As shown in FIG. 2, the hygroscopic body of the present invention can be formed into a cylindrical shape to form a cylindrical hygroscopic body 21. A breathable film 3 is attached to the annular moisture absorbent body 31 as shown in FIG.
3 can be attached. As shown in FIG. 4, the moisture absorbent body 41 of the present invention is punched into a disk shape, a breathable film 43 is attached as in FIG. 3, and a vegetable oil film 45 is further coated on the circumferential surface. I can do it. The hygroscopic body of the present invention can be used for product cases, as shown in FIG. can do. Further, as shown in FIG. 6, the moisture absorbent body 61 of the present invention can be cut into a special shape depending on the place of use, and a breathable film 63 can be attached to the surface thereof.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of an apparatus for carrying out the #lJ manufacturing method of the moisture absorbent of the present invention, and FIGS. FIG. 3 is a perspective view showing a moisture absorbent body processed and molded accordingly. DESCRIPTION OF SYMBOLS 1... Urethane foam roll, 2... Urethane foam sheet, 3... Pull-out roller, 4... Band for calcium chloride spraying, 5... Nozzle, 6... Bong 1.7...
- Impregnation zone, 8...bath, 9...roller, 10...
Drying zone, 11... Heater, 12... Blower, 13
... Glue supply source, 14 ... Film supply roll, 15
...Film, 16...Moisture absorbent sheet, 17...
Press machine, 21... Hygroscopic body, 31... Hygroscopic body, 33
...Breathable film, 41...Moisture absorber, 43...
Breathable film, 45... Oil film, 51... Hygroscopic body,
53... Breathable film, 61... Moisture absorber, 63.
...Breathable film.

Claims (1)

[Scope of Claims] 1. A hygroscopic material characterized in that calcium chloride particles are contained within foamed urethane foam using a moisture retaining agent. 2. The hygroscopic body according to claim 1, wherein the moisture retaining agent comprises at least one type of clay mineral. 3. The moisture absorbent according to claim 1 or 2, wherein the calcium chloride particles are accommodated by fixing the calcium chloride particles to the inner wall of the bubble via a moisture retaining agent. 4. The calcium chloride particles are accommodated by filling a moisture retaining agent into the foam at least in the surface phase of the urethane foam to an extent that does not impair the air permeability of the urethane foam. The moisture absorbent according to item 1 or 2. 5. A method for producing a moisture absorbent in which calcium chloride particles are contained in foamed urethane foam using a moisture retaining agent, which comprises the following steps. (a) A step of spraying powdered calcium chloride onto one side of the supplied urethane foam and simultaneously sucking air from the other side of the urethane foam to draw calcium chloride particles into the foam of the urethane foam. (b) Foaming containing calcium chloride particles. For urethane,
A step (c) of impregnating the urethane surface with a water retention agent solution (c) a step 6 of drying the foamed urethane containing the water retention agent solution, the moisture retention agent comprising at least one type of clay mineral, claimed in claim 5. manufacturing method.