JP2002292236A - Method for manufacturing planar sealed humidity conditioning sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a planar sealed humidity conditioning sheet from which an inorganic moisture absorbent does not drop out of a cut plane or a pleat folded plane and which has improved powder dropping property in the planar sealed humidity conditioning sheet in which the inorganic moisture absorbent is sealed in two base material sheets. SOLUTION: The method for manufacturing the planar sealed humidity conditioning sheet is characterized by that the inorganic moisture absorbent and a thermoplastic binder are arranged at a fixed space on a base material, are subjected to heat treatment then another base material is superposed thereon and the base materials of both sides are bonded by heating and/or pressing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a humidity control sheet, and more particularly, to a method for producing a humidity control sheet in which an inorganic hygroscopic agent is sealed between two substrates.

[0002]

2. Description of the Related Art Conventionally, most moisture conditioning materials or moisture absorbing materials using an inorganic moisture absorbing agent are obtained by packing a particulate or powdery moisture absorbing agent in a bag of a nonwoven fabric having air permeability.
It was mainly used to prevent food from drying out. These have a bag-like shape, absorb moisture in a very limited space, and are not used for a filter for humidity control or an air conditioner having a very large processing capacity.

[0003] A method for producing a humidity control sheet in which an inorganic hygroscopic agent is sandwiched between two air-permeable sheets is such that the inorganic hygroscopic agent does not peel off and the surface of the inorganic hygroscopic agent is covered with a binder resin. It is intended to provide a humidity control sheet having a small decrease in moisture absorption effect without having an advantage that the inorganic moisture absorbent can be increased as required and the moisture absorption capacity can be increased. The practicality was particularly excellent.

However, an important problem is that in the method of sandwiching the inorganic moisture absorbent between the two base sheets as described above, the inorganic moisture absorbent is present on the entire surface of the completed humidity control sheet. When the inorganic moisture absorbing agent falls off from the cut surface, or when it is pleated (folded), there is a structural problem such that the internal inorganic moisture absorbing agent breaks through the base sheet at the folded portion.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a planar sealed humidity control sheet in which an inorganic hygroscopic agent is encapsulated in two base sheets, wherein the internal inorganic hygroscopic agent has a cut surface or folds. An object of the present invention is to provide a method for producing a planar encapsulated humidity-controlled sheet which does not fall off from the surface and has improved powder-falling properties.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to solve the above problems, and as a result, have reached the present invention.

An inorganic hygroscopic agent and a thermoplastic binder are arranged at regular intervals on a substrate, and after heat treatment, another substrate is overlaid, and the substrate on both sides is heated or pressed or both. A method for producing a planar encapsulated humidity control sheet, characterized in that:

[0008] An inorganic hygroscopic agent and a thermoplastic binder are arranged at regular intervals on a substrate, and only a binder is arranged in a region where the inorganic hygroscopic agent is not arranged. The method for producing a planar encapsulated humidity control sheet as described above, wherein the base material on both sides is adhered by laminating, heating or pressing, or both.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a humidity control sheet in which an inorganic hygroscopic agent is sealed in two base sheets (hereinafter, referred to as a base material A and a base material B). Provided is a method for producing a moisture-conditioning sheet that does not fall off from a surface or a fold-folded surface and has improved powder-falling properties.

The base material A or base material B according to the present invention includes woven fabrics, nonwoven fabrics, nets, sponges, etc., as well as general-purpose thermoplastic films such as polyethylene films, polypropylene films, and polyester films, and thin plates. Is mentioned. Of these, a sheet having poor air permeability such as a film or a thin plate may be formed into a fine hole to improve air permeability, and may be used as a gas permeable filter.

Among them, in particular, when a non-woven fabric or the like is used, not only is it possible to ensure relatively uniform air permeability, but also it is easy to enclose, so that it is advantageously used. The substrate A and the substrate B may be the same or different substrates. At least either the base material A or the base material B needs to have appropriate air permeability (moisture permeability).

The base material A or base material B according to the present invention may have antibacterial, antifungal, antiviral, insect repellent, pest repellent, moisture absorbing, deodorizing, deodorizing, raising, printing, coloring, embroidery, embossing, if necessary. A device having such a function may be used.

[0013] Woven and nonwoven fabrics include polyamide fibers,
Synthetic fiber such as polyester fiber, polyalkylene paraoxybenzoate fiber, polyurethane fiber, polyvinyl alcohol fiber, polyvinylidene chloride fiber, polyvinyl chloride fiber, polyacrylonitrile fiber, polyolefin fiber, phenol fiber, and glass Inorganic fibers such as fibers, metal fibers, alumina fibers, and inorganic moisture absorbent fibers, natural fibers such as wood pulp, hemp pulp, and cotton linter pulp, regenerated fibers, and hydrophilic, flame retardant, and moisture absorbing properties of these fibers It is manufactured by various methods using fibers or the like imparted with functions such as absorption, antibacterial properties, and the like.

There are no particular restrictions on the method for producing the woven or nonwoven fabric, and it is used according to the purpose and application. Especially for nonwoven fabrics, the web obtained by dry method, wet papermaking method, melt blown method, spun bond method, etc. It can be manufactured by appropriately combining a method and a method of developing strength by an adhesion method using an adhesive such as a resin bond.

[0015] The base material according to the present invention is an electret filter, a HEPA filter, a filter carrying a fragrance, a deodorizing filter, an adsorbent or a catalyst is kneaded in a thermoplastic resin, and a part thereof is exposed on the surface. A filter, a filter carrying an inorganic hygroscopic agent such as an enzyme, or a filter carrying a deodorant or an antibacterial agent can be used.

The electret filter according to the present invention is a filter that maintains electric polarization semipermanently and applies an electric force to the outside, and captures particles by the electrostatic force. Examples of the charging method include an electro-electret, a heat electret, a radio-electret, a mechano-electret, a photo-electret, and a magnet-electret. As a filter material, polypropylene or a propylene-based copolymer is often used.

Since the nonwoven fabric is bulky and has three-dimensional voids, it is difficult to obtain a stable charging effect by charging treatment using corona discharge or the like. However, a film that has been subjected to charging treatment by corona discharge or the like is cut into a fibrous form, and a split fiber electret filter made of non-woven fabric, or a high voltage is applied during melt blown spinning and melt spinning to charge the fiber like a heat electret. The melt blown nonwoven fabric type electret filter and the spunbond nonwoven fabric type electret filter can obtain a stable polarization charge.

Since the melt blown nonwoven fabric type electret filter has a small mechanical strength by itself, it may be used by laminating a dry nonwoven fabric or a spun bond.

The HEPA filter according to the present invention is:
An ultra-high-performance dust collection filter having a dust collection efficiency of 99.97% or more for 0.3 μm particles. Conventionally, HEPA filters have been used for special purposes such as for military use, for radioactive waste, and for clean rooms. However, in recent years, the use of HEPA filters has tended to expand to household use such as home air purifiers.

The inorganic hygroscopic agent according to the present invention is a general term for chemicals mainly used for removing moisture and water vapor in the air. Specifically, silica gel, zeolite, synthetic zeolite, activated alumina, active alumina, Examples include clay, acid clay, and calcium oxide. Charcoal or activated carbon is also within the scope of the present invention as long as it is used for humidity control. If necessary, a plurality of these inorganic moisture absorbents may be used in combination, or a hybrid inorganic moisture absorbent obtained by combining these inorganic moisture absorbents may be used.

The binder according to the present invention is a thermoplastic resin, a thermosetting resin, a hot melt, a heat seal, a two-part curing type adhesive, a moisture curing type adhesive, an ultraviolet ray or an electron beam curing type adhesive, and the like. Among them, examples of the thermoplastic resin that is used predominantly include ethylene vinyl acetate copolymers or modified products thereof, ethylene acrylate copolymers, ionomers, polyamides, nylons, polyesters, polyethylenes, polypropylenes, and polyurethane-based resins. it can.

The softening point or melting point of the binder according to the present invention is not particularly limited, and may be appropriately determined in consideration of the post-processing conditions of the humidity control sheet, the use environment temperature, the heat resistance of the base material or the inorganic moisture absorbent, and the like. Just choose.

The shape of the inorganic moisture absorbent according to the present invention is preferably in the form of powder, granules, or whiskers. The particle size of the inorganic moisture absorbent or the thermoplastic adhesive according to the present invention is preferably 5 to 500 mesh. If the particle size is less than 5 mesh, the inorganic hygroscopic agent breaks when pressurized,
There are problems such as non-uniform adhesion points between the substrates, and on the other hand, when the particle size exceeds 500 mesh, there is a problem such as separation from the eyes of the substrate. For the same reason, the shape of the binder according to the present invention can also take various forms such as powder, granule, whisker, short fiber, long fiber, and further liquid, semi-solid, sheet and the like. It is also possible to take the form.

The amount of the inorganic moisture absorbing agent according to the present invention is as follows:
Although it is not particularly limited, it is preferably 1200 g / m ² or less. If the encapsulation amount exceeds 1200 g / m ² , the adhesive strength between the substrates becomes low, and the thickness becomes large to make pleating difficult, so that the practicality decreases.

When the inorganic moisture-absorbing agent and the thermoplastic adhesive are sprayed on the substrate according to the present invention, the two may be sprayed individually, but if the moisture-absorbing property is not particularly affected, the two may be mixed in advance. It is preferable to spray what was done. As a method of spraying, spraying by free fall from the lower part of the hopper, a method of continuously supplying a roll having a concave portion such as a gravure roll and supplying the roll onto a substrate, spraying by blowing air dispersed in air,
Spray coating and die coating with aqueous dispersion can be mentioned.

In the present invention, a portion in which an inorganic hygroscopic agent is arranged at regular intervals on the inner surface of the planar enclosed humidity control sheet;
It is necessary to provide a portion in which the inorganic moisture absorbent is not provided and to bond the planar encapsulated humidity control sheet. In order to arrange the inorganic hygroscopic agent at regular intervals, a method of continuing and interrupting the drop of the inorganic hygroscopic agent from the hopper at regular intervals while the base material is running, regularly on rolls having concave portions such as gravure rolls The method of supplying the inorganic moisture absorbent on the base material regularly by creating a place where no concave portion is provided, and the supply of the inorganic moisture absorbent by regularly interrupting the ventilation in the dispersion by the air dispersed in the air. Means for controlling, means for mechanically controlling the supply of the inorganic hygroscopic agent by spray coating or die coating with aqueous dispersion and the like can be mentioned.

In the present invention, it is necessary to supply only the binder to the portion where the inorganic hygroscopic agent is not disposed on the inner surface of the planar enclosed humidity control sheet. The method can be roughly divided into two methods. The first is a method in which a binder is sprayed on the entire surface of the substrate irrespective of the presence or absence of the inorganic hygroscopic agent. The spraying of the binder is performed before or after the inorganic hygroscopic agent is sprayed. But you can.

The second is a method of disposing a binder only in a portion where the inorganic moisture absorbent is not arranged, which is completely opposite to the intermittent supply of the inorganic moisture absorbent while the base material is running. A method of continuing and suspending the dropping of the binder from the hopper as described above, the binder is regularized by another gravure roll having a concave portion only in the non-supplying portion of the gravure roll supplied with the inorganic moisture absorbing agent (ie, the arrangement of the inorganic moisture absorbing agent). A technique of intermittently supplying an inorganic hygroscopic agent, such as a method of supplying an inorganic hygroscopic agent only to a portion not to be used, can be used.

At this time, there is no problem in detecting the presence or absence of the inorganic hygroscopic agent with a timing mark or the like to determine the timing of supplying the binder.

In the present invention, the bonding of two substrates can be achieved by heating or pressurizing, or both. The heating method is not particularly limited, but when the binder is a thermoplastic resin, it is preferable to heat from the side where the binder is sprayed. The timing of heating may be any time after the thermoplastic resin is sprayed and after the non-sprayed substrate is overlaid, and heating may be performed at both timings. When heating from the side where the thermoplastic resin is sprayed, since it is difficult to heat by contact heat conduction, it is preferable to use a non-contact heating means such as hot air, among which infrared heaters and gas burner heaters Such a means using radiant heat is particularly preferred.

The pressurization after laminating the substrates according to the present invention can employ, for example, a method of passing between pressurized rolls. The degree of pressurization depends on the adhesive strength, collapse of the inorganic moisture absorbent,
What is necessary is just to set suitably in consideration of the influence on air permeability.

The present invention is directed to a planar encapsulated humidity control sheet in which an inorganic hygroscopic agent is sandwiched between two substrates, when the inorganic hygroscopic agent falls off from the cut surface or when the inorganic hygroscopic agent is pleated (folded). In the folded portion, the problem that the internal inorganic moisture absorbent breaks through the base sheet is solved, but the inorganic moisture absorbent is arranged at regular intervals on the inner surface of the planar enclosed humidity control sheet. In addition, by providing a region where the inorganic moisture absorbent is not disposed, the region where the inorganic moisture absorbent is not disposed is cut or folds of the pleats to prevent the inorganic moisture absorbent from falling off and breaking the base sheet. is there.

Further, in the present invention, an inorganic hygroscopic agent is arranged at regular intervals on the inner surface of the planar sealed humidity control sheet, and a region where the inorganic hygroscopic agent is not provided is provided. By providing only the binder in the area where is not arranged, it is possible to increase the strength in the state of bonding, and the area provided with only the binder is cut or folds of the pleats, so that the inorganic moisture absorbent falls off Or torn base material sheets.

[0034]

EXAMPLES The present invention will be described below with reference to examples, but it should not be construed that the invention is limited thereto without departing from the spirit of the present invention.

Preparation Example 1 Polypropylene fiber (4d, 38mm, 50w%), polyethylene fiber (6d, 51mm, 30w%) and viscose rayon fiber (3d, 51mm, 20w%) were mixed and dried in air by a dry method. To form a web, then
It was impregnated in acrylic latex, which is a thermoplastic binder, and was formed by bonding fibers to obtain a base material A as a nonwoven fabric. Next, this nonwoven fabric was impregnated with a coating solution containing an antibacterial agent carrying persimmon catechin and carried at 20 g / m ² to prepare an antibacterial / antifungal base material B.

Preparation Example 2 A mixture of 50 parts by weight of granular silica gel and 50 parts by weight of granular zeolite was used as an inorganic moisture absorbent, and a total of 100 parts of the mixture was mixed with a thermoplastic adhesive as a binder for the inorganic moisture absorbent. 50 parts by weight of ethylene vinyl acetate resin powder having a softening point of 90 ° C. was mixed to prepare a moisture-absorbing mixed powder.

Preparation Example 3 As a binder containing no inorganic moisture absorbent, ethylene vinyl acetate resin powder having a softening point of 90 ° C., which is a thermoplastic adhesive, was used.

Example 1 The moisture-absorbing mixed powder of Preparation Example 2 was sprayed on the substrate B of Preparation Example 1 at a rate of 100 g / m ² over a square area of 24 cm square. The square on which the moisture-absorbing mixed powder is sprayed is 2 cm from each side
At each ratio, the adjacent moisture-absorbing mixed powder is arranged through the portion where the moisture-absorbing mixed powder (inorganic hygroscopic agent) is not provided. In the production, a gravure-type rotating roll was used, the moisture-absorbing mixed powder was dropped from above the rotating roll, and the supply and non-supply of the moisture-absorbing mixed powder were determined by the arrangement of the concave portions of the gravure roll. Heating was performed from the side where the mixed powder was sprayed using a far-infrared heater having a surface temperature of 150 ° C.
After the thermoplastic binder has been plasticized, the heating is stopped, and the antibacterial and antibacterial preparations of Preparation Example 1 are immediately applied to the side of the base material B where the inorganic moisture absorbent is sprayed.
The antifungal base material A was overlaid, sandwiched between two rotating rolls, and pressure-integrated to produce a planar encapsulated humidity control sheet.
This was used as the method for manufacturing the planar enclosed humidity control sheet of Example 1.

Example 2 On the substrate B of Preparation Example 1, the moisture-absorbing mixed powder of Preparation Example 2 was sprayed on a square area of 24 cm square at a rate of 100 g / m ² . The square on which the moisture-absorbing mixed powder is sprayed is 2 cm from each side
At each ratio, the adjacent moisture-absorbing mixed powder is arranged through the portion where the moisture-absorbing mixed powder (inorganic hygroscopic agent) is not provided. The binder of Preparation Example 3 alone was sprayed at a rate of 100 g / m ^{2 on} the portion where the moisture-absorbing mixed powder (inorganic moisture absorbent) having a width of 2 cm was not provided. In the production, two gravure-type rotating rolls are used, and supply and non-supply of the moisture-absorbing mixed powder are determined by the arrangement of the concave portions of the gravure roll. Determined by Heating was performed from the side where the mixed powder was sprayed using a far-infrared heater having a surface temperature of 150 ° C. After the thermoplastic binder is plasticized, the heating is stopped, and a commercially available electret filter (PO-20ALOG, manufactured by Tonen Tapyrus Co., Ltd.) is superimposed as the base material A on the side of the base material B on which the inorganic hygroscopic agent is sprayed. The sheet was sandwiched between rotating rolls and pressurized and integrated to produce a planar enclosed humidity control sheet. This was used as the method for manufacturing the planar enclosed humidity control sheet of Example 2.

Comparative Example 1 The moisture-absorbing mixed powder of Preparation Example 2 was sprayed on the entire surface of the base material B of Preparation Example 1 at a rate of 100 g / m ² . In the production, a gravure type rotating roll was used, and the moisture-absorbing mixed powder was continuously supplied. Heating was performed from the side where the mixed powder was sprayed using a far-infrared heater having a surface temperature of 150 ° C. After the thermoplastic binder is plasticized, the heating is stopped, and the antibacterial and antifungal base material A of Preparation Example 1 is immediately superimposed on the base material B on the side where the inorganic hygroscopic agent is sprayed, and between the two rotating rolls. The sheet was sandwiched and pressurized and integrated to produce a planar enclosed humidity control sheet. Comparative Example 1
The method for producing a planar encapsulated humidity control sheet described above was used.

Comparative Example 2 In Comparative Example 1, a commercially available electret filter (manufactured by Tonen Tapils, PO-20) was used in place of the substrate A of Preparation Example 1.
Except that ALOG) was used as the base material A, a planar encapsulated humidity control sheet was produced in the same manner as in Comparative Example 1 in all cases. This was used as the method for producing the planar enclosed humidity control sheet of Comparative Example 2.

As described above, the flat enclosed humidity control sheets obtained by the production methods of Examples and Comparative Examples were subjected to a powder drop test and a pleating test by the following methods. The results are shown in Table 1.

[Powder drop test] The planar sealed humidity control sheets of the examples and the comparative examples were cut into a size of 26 cm square. 2
Ten sheets of the enclosed sealed humidity control sheet cut to 6 cm square were stacked and vigorously shaken for 5 minutes in the box. The inorganic moisture absorbent dropped in the box was collected and weighed. It is unlikely that there is no powder dropping. Therefore, under this measurement condition, 10 mg or less was evaluated as excellent, 20 mg or less being heavier than 10 mg, good being 50 mg or less being heavier than 20 mg, and the case of exceeding 50 mg was evaluated as poor.

[Pleated Folding Test] The planar sealed humidity control sheets of the examples and comparative examples were pleated at intervals of 26 cm. After being folded 100 times, it was spread again and returned to a flat shape, and the state of the front and back of the folded surface was confirmed. Under these measurement conditions, those with no breaks such as the internal inorganic hygroscopic agent protruding from the folded surface are excellent, and one or more and ten or less are lined up.
The case where the number was more than 10 was evaluated as poor. Naturally, if there is such a broken portion, there is a danger that the inorganic hygroscopic agent will fall out of the broken portion, and there is a problem that the air leaks and the dust removing performance is reduced.

[Dehumidification Test] The planar sealed humidity control sheets of Examples and Comparative Examples were cut into 26 cm squares, placed in a large desiccator, and fed with moist air to measure the dehumidification status with a hygrometer. As a result of this test, there was no significant difference in the dehumidification performance of the planar encapsulated humidity control sheets obtained in Examples and Comparative Examples, and they had substantially the same dehumidification properties.

[Adhesiveness Test] The planar sealed humidity control sheets of Examples and Comparative Examples were cut into 26 cm squares, and the base material A and the base material B were peeled off from their edge surfaces to determine the adhesiveness. Peel strength between substrates A and B measured by Tensilon is 100 gf /
Excellent adhesiveness as 25 mm or more is difficult to peel off,
Adhesion was equal when the size was greater than 50 gf / 25 mm and less than 100 gf / 25 mm, and poor when the size was less than 50 gf / 25 mm.

[0047]

[Table 1]

From the results in Table 1, it can be seen that the planar encapsulated humidity control sheet obtained by the production method of the example is compared with the planar encapsulated humidity control sheet obtained by the production method of the comparative example using the same base material. It was found that the powder drop prevention performance was very high, and that there were no breaks, so that not only the inorganic hygroscopic agent did not fall off from the fracture surface, but also the dehumidification performance was good.

[0049]

According to the present invention, in a method for producing a planar encapsulated humidity control sheet in which an inorganic hygroscopic agent is encapsulated in two base sheets, the internal inorganic hygroscopic agent falls off the cut surface or the folded surface. It is possible to provide a flat enclosed humidity control sheet having improved powder-falling properties without any need to perform.

Claims (2)

[Claims] Claims 1. An inorganic moisture absorbent and a thermoplastic binder are arranged at regular intervals on a base material, and after heat treatment, another base material is overlaid and heated or pressed, or both of the base materials are heated and pressed. A method for producing a planar encapsulated humidity control sheet, comprising bonding a substrate. 2. An inorganic moisture-absorbing agent and a thermoplastic binder are arranged at regular intervals on a substrate, and only a binder is arranged in a region where the inorganic moisture-absorbing agent is not arranged. 2. The method for producing a planar encapsulated humidity control sheet according to claim 1, wherein the materials are overlapped and the substrates on both sides are adhered by heating or pressurizing, or both.