JPH0539379A - Moisture conditioning composition and moisture conditioning molded article - Google Patents

Abstract

PURPOSE:To provide a moisture conditioning composition and a moisture conditioning molded article which have a moisture conditioning function capable of maintaining humidity constant. CONSTITUTION:The objective moisture conditioning composition prepared by mixing 100 pts.wt. thermoplastic resin with 5-400 pts.wt. magnesium sulfate represented by formula MgSO4.nH2O (wherein 0<=n<=3) and having an average particle size of 30mum or less, and the moisture conditioning molded article such as film prepared from the composition.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a humidity-controlling composition having a humidity-controlling function capable of keeping humidity at a constant humidity, and a humidity-controlling molded article obtained from the composition.

[0002]

2. Description of the Related Art Conventionally, desiccants such as silica gel, calcium chloride, quick lime, zeolite, etc. for the purpose of preventing quality deterioration of products such as foods, pharmaceuticals, electronic parts, precision machinery, etc. due to oxidation due to moisture absorption. Is used. These desiccants are in a granular or powder state,
It is used by being wrapped with paper, non-woven fabric, or the like, or being put in a packaging material together with a product in a state of being enclosed in a container or the like.

[0003]

The desiccants such as silica gel, zeolite, calcium chloride and quick lime that have been conventionally used as desiccants have strong drying power and hygroscopicity due to their physical and chemical properties, and are hermetically sealed containers. Also, when placed in a bag or the like, the water inside is taken for a short period of time, and the water inside is taken infinitely until the humidity reaches 0%. This is the chemical and physical action of each desiccant, and when used by putting it in the packaging material used to seal the product from the outside, keep the humidity constant and keep it appropriate for the contents. I couldn't keep the humidity. That is, the conventional desiccant has no humidity control function.

The present invention has a humidity-controlling composition having a humidity-controlling function which is not possible with a conventional desiccant and having a humidity-controlling function capable of maintaining an arbitrary constant humidity in the range of 60 to 10%. And a humidity-conditioning molded article obtained from this composition.

[0005]

Means for Solving the Problems The present invention has been completed as a result of intensive studies conducted by the present inventors in order to achieve the above object. By blending a specific amount, the present invention succeeded in providing a humidity-controlling composition having a humidity-controlling property and also excellent in hygroscopicity, scattering property, sustainability and deliquescent property.

That is, the humidity control composition of the present invention has the formula MgSO ₄ .nH _{2 with} respect to 100 parts by weight of the thermoplastic resin.
O (however, 0 ≦ n ≦ 3) and has an average particle size of 30
5 to 400 parts by weight of magnesium sulfate having a size of μm or less is blended.

When magnesium sulfate defined in this way absorbs moisture, hexahydrate is first formed, and as the amount of absorbed moisture increases, only hexahydrate increases, while 1-5 hydrate does not form, It is a humidity control agent that changes to 7-hydrate when the amount of the anhydrous salt becomes small, that is, when the water absorption is 43 to 48%.

The thermoplastic resin used in the present invention is not particularly limited, and known ones can be used. For example, polyethylene (PE), polypropylene (PP), polycarbonate, polyamide (PA), Ethylene-vinyl acetate copolymer (EVA), ethylene-methyl acrylate copolymer (EMA), ethylene-methacrylate
Copolymers, polyvinyl chloride, polystyrene, polyester, polyvinylidene chloride (PVDC), and the like,
One or more of these can be used.

In the present invention, the humidity control agent used together with the thermoplastic resin is represented by the formula MgSO ₄ .nH ₂
Magnesium sulfate represented by O (where 0 ≦ n ≦ 3), particularly magnesium sulfate having excellent dispersibility in the resin, is preferable. Magnesium sulfate hydrate that exceeds trihydrate, when kneading with resin, releases its own water of hydration due to the heating during kneading, which causes problems during production.
It is not possible to obtain a humidity control composition capable of exerting an effective function, and even if an attempt is made to form a molded article such as a film, a sheet or a container from this composition, a humidity control molded article having commercial value is obtained. Can't get The above-mentioned humidity conditioner has an average particle diameter of 30 μm or less. Such magnesium sulfate having a small average particle diameter has a maximum fluctuation range of the specific surface area of 4.0 to 1.5 m ² / g, and its fluctuation is small.
If necessary, magnesium sulfate having different particle diameters may be kneaded and used.

When the average particle diameter of magnesium sulfate exceeds 30 μm, the moisture absorption rate of the hygroscopic composition becomes slow. Further, when the fluctuation of the specific surface area of magnesium sulfate becomes large, and a molded article is produced from the humidity control composition,
Due to the absorption of moisture, the molded product expands, contracts, and cracks, so that the dimensional stability cannot be maintained and a practical molded product cannot be obtained.

In the present invention, the ratio of the raw materials to be blended is
The humidity control agent is 5 to 400 parts by weight with respect to 100 parts by weight of the thermoplastic resin, and is appropriately selected within this range according to the application. When the proportion of the humidity control agent is in the above range, the dispersibility of the humidity control agent in the resin is good, and the humidity control property, the hygroscopicity, the water retention property and the durability are high, and the moldability is excellent. The humidity control composition intended by the present invention can be obtained.

In the humidity control composition of the present invention, in addition to the thermoplastic resin and the humidity control agent, a foaming agent may be added as a raw material. The foaming agent is not particularly limited and widely known agents can be widely used. Examples thereof include azoisobutyronitrile, azodicarbonamide, and 4,4′-oxybenzenesulfonyl hydrazide.
The amount of the foaming agent used is 100 parts by weight of the thermoplastic resin,
0.2 to 10 parts by weight is preferable. The foamed humidity-controlling molded article obtained from the foaming humidity-controlling composition to which the foaming agent is added is lightweight and has a higher hygroscopic force because the hygroscopic effect extends to the inside of the foamed article.

Besides, a plasticizer known as an additive,
Stabilizers, lubricants, coloring agents and the like may be added as needed, as long as they do not impair the object of the present invention.

The present invention also includes a humidity-controlling molded article obtained by molding the humidity-controlling composition of the present invention.

The method for producing the humidity control composition of the present invention and the molded article thereof is not particularly limited, and it can be usually produced by the following method. That is, about 100 to about 100 parts of the above-mentioned thermoplastic resin, humidity control agent and, if necessary, other additives are mixed using a kneading machine such as mixin-gall or a kneading molding machine.
A humidity-controlling composition can be obtained by kneading at a temperature of 350 ° C. for about 5 to 40 minutes, and a humidity-controlling molded article can be obtained by molding the composition.

Further, the humidity control molded article of the present invention includes a laminated humidity control molded article obtained by laminating at least one of the humidity control laminates obtained from the humidity control composition. Other laminated materials to be laminated with the humidity-controlling laminated material include resins such as the above-mentioned thermoplastic resins which are raw materials of the composition of the present invention,
Papers, fibers, metals, various paints, various adhesives, etc. can be used. Note that at least one of the humidity-controlling laminates obtained from the humidity-controlling composition of the present invention means that two or more kinds of laminates obtained from the humidity-controlling composition of the present invention having different compositions can also be used. .. Type of laminated material,
The amount (thickness) and the number of laminated layers are not limited as long as the object of the present invention is achieved, and can be widely used.
It is selected as appropriate.

The most common example of the lamination is a film, sheet or plate laminated with the humidity control laminate. Specific examples of the resin structure in the case of this laminated structure are listed below, but the present invention is not limited to this.

Low Density Polyethylene (LDPE) / Medium Density Polyethylene (MDPE) High Density Polyethylene (HDPE) / LDPE / HDPE HDPE / LDPE / LDPE HDPE / EMA / LDPE HDPE / Ionomer PA / Ionomer PP / EVA / PP PP / EVA / LDPE PA / Adhesive PE / Ionomer-PA / Adhesive PE / EVA PA / Adhesive PE / HDPE PA / Adhesive PE / Linear low-density polyethylene (LLD)
PE) PA / adhesive LLDPE / LLDPE PA / adhesive PP / PP LDPE / PA / EVA EVA / PVDC / EVA EVA / PVDC / ionomer-LDPE / adhesive PE / PA In the above lamination example, “adhesiveness” Means laminating with an adhesive. The humidity control agent may be contained in any of the above resin layers, but it is not necessary to contain it in the outer layer since the main purpose of lamination is to produce the hygroscopic packaging material.
Further, aluminum foil or the like can be attached to block moisture and light from the outside almost completely. The stack is
Extrusion lamination method, coextrusion lamination method,
It can be easily carried out by a multi-layer injection molding method, an adhesion method or the like, and the resulting laminate can be easily further processed into a bag shape or a container shape. Thus, as the packaging material, the laminated humidity-conditioning molded article of the present invention in which a waterproof material is laminated on the outer layer and a moisture-permeable protective material is laminated on the inner layer, if necessary,
Humidity control and moisture absorption effect, its life, durability, light shielding property, antistatic property, safety and stability are improved, and it is more excellent in quality deterioration prevention effect, and more functional that can be used in all usage environments. It is a thing.

The humidity control composition of the present invention comprises extrusion molding, coextrusion molding, injection molding, blow molding, extrusion coating molding,
By a method such as cross-linking foam molding, a film shape, a sheet shape,
A humidity control molded product is obtained by processing and molding into a plate shape, a bag shape, a pellet shape, a container shape, a laminated body shape or the like. It should be noted that the term "container shape" here means not only the container itself, but also a container lid and a combination of the container and the lid.

[0020]

In the magnesium sulfate used in the present invention, when moisture absorption starts under constant temperature conditions, the vapor pressure increases as the hydration stage progresses, and the difference with the partial pressure of environmental water vapor decreases accordingly. Therefore, the rate of moisture absorption decreases, and as a result, a composition having a humidity control function while maintaining a constant humidity can be obtained.

Further, when magnesium sulfate used in the present invention absorbs moisture, hexahydrate is first produced, and only hexahydrate increases as the amount of moisture absorption increases, and 1-5 pentahydrate is not formed in the meantime. , When the amount of anhydrous magnesium sulfate becomes very small, that is, when the water absorption rate is 43 to 48%, it changes into a heptahydrate. Due to this fact, unlike other desiccants using salts capable of forming hydrates, an anhydride is present even at the time of high moisture absorption, and the composition has a humidity control function by keeping the moisture absorption power constant.

Furthermore, the magnesium sulfate used in the present invention itself exhibits a certain constant vapor pressure, and can absorb moisture up to the point where the partial pressure of water vapor in the external environment and its own vapor pressure are in equilibrium. When the above magnesium sulfate is kneaded into the resin, the composite of the resin and magnesium sulfate exhibits a constant vapor pressure. The vapor pressure at this time is different from that of magnesium sulfate alone, and is affected by the moisture permeability of the kneaded resin, and has a different value depending on the resin. In that case, naturally, the point at which equilibrium is reached is different, and the equilibrium humidity at which moisture cannot be absorbed is also different. Therefore, the constant humidity to be held can be adjusted appropriately by the resin.

[0023]

【Example】

Example 1 100 parts by weight of ethylene-methyl acrylate copolymer (EMA, density 0.942 g / cm ³ ), anhydrous magnesium sulfate (average particle diameter 4.59 μm, specific surface area 4.0 to 4.0)
After kneading 100 parts by weight of 1.5 m ² / g) with a kneading extruder (PCM45 twin screw extruder manufactured by Ikegai Tekko KK),
Hot cutting was performed to produce pellets, and a sheet having a thickness of 0.5 mm was produced by the T-die method. Low density polyethylene (density 0.921 g / cm ³ ) for comparison
100 parts by weight and 50 parts by weight of zeolite (average particle diameter 8 μm) were kneaded in the same manner, and the thickness was 2 m by an injection molding machine.
m plate was prepared. Similarly, for comparison, low-density polyethylene and silica gel (particle size 200 to 300 mesh) were kneaded in the same manner as in the case of zeolite, and a plate having a thickness of 2 mm was produced by an injection molding machine.

Using these sheets and plates as samples,
They were packed in separate glass containers (capacity 0.9 L) and the relationship between the moisture absorption rate and time in the glass containers was measured at room temperature, and the results are shown in FIG.

As is clear from the results of FIG. 1, in the case of the sample using zeolite and silica gel, the humidity in the glass container was 0%, and the humidity could not be kept constant, and the humidity control function was not achieved. You can see that there is no. On the other hand, in the case of the sample of the present invention using anhydrous magnesium sulfate,
It can be seen that the humidity can be kept at 19% and the humidity control function is provided. Example 2 100 parts by weight of polyamide and anhydrous magnesium sulfate (average particle size 4.59 μm, specific surface area 4.0 to 1.5 m ² /
g) 50 parts by weight was kneaded with the kneading extruder used in Example 1, hot cut to prepare pellets, and a sheet having a thickness of 0.5 mm was prepared by the T-die method. .. A sheet having a thickness of 0.5 mm was prepared from polypropylene and anhydrous magnesium sulfate by the same method. The former and latter sheet samples were packed in separate glass containers (capacity 0.9 L), and the temperature was adjusted to 25 ° C. in order to examine the humidity control, recovery and sustainability of the former and latter samples in the glass containers.
The recovery limit of moisture absorption in the closed space in the glass container within a fixed time (48 hours) was continuously measured in the above, and the results for the former and latter samples are shown in FIGS. 2 and 3, respectively.

As is clear from FIGS. 2 and 3, it can be seen that the samples of the present invention have a humidity control power, a recovery power, and a sustaining power. Further, it is apparent that the humidity can be adjusted to an arbitrary humidity in the present invention by changing the type of the thermoplastic resin. Example 3 (A) Low-density polyethylene (density 0.921 g / c
m ³ ) 100 parts by weight and 50 parts by weight of anhydrous magnesium sulfate used in Example 1 were kneaded by the kneading extruder used in Example 1, hot cut to prepare pellets, and then inflation. By the method, a three-layer film including a low density polyethylene film containing 33% anhydrous magnesium sulfate was prepared. As shown in FIG. 4, the contents of the three layers are, as shown in FIG. 4, an outer layer of a high-density polyethylene layer 1 having a thickness of 50 μm and an intermediate layer of 33% magnesium sulfate.
Containing a low-density polyethylene layer 2 having a thickness of 50 μm and an inner low-density polyethylene layer 3 having a thickness of 10 μm,
A three-layer inflation film 4 having a thickness of 110 μm, which is further formed from this film 4 into a bag (300 × 200 ×).
0.11 mm) was produced. (B) Magnesium sulfate-containing ethylene-methyl acrylate copolymer layer having a thickness of 50 μm, obtained by containing 33% of the above anhydrous magnesium sulfate in the ethylene-methyl acrylate copolymer used in Example 1. A three-layer inflation film was prepared in the same manner as in the above (A) except that 5 was used as the intermediate layer, and a polyethylene terephthalate (PET) layer (thickness: 12 μm) was formed on the outer layer thereof.
m) 6 / Al layer (thickness 9 μm) 7 / LDPE layer (thickness 1
5 μm) 8 and an Al coat film layer composed of 8 are laminated to form an Al coat laminating film 9 (FIG. 5) having a thickness of 146 μm.
00 × 200 × 0.146 mm) was produced. (C) The thickness of the outer HDPE layer 1 and the thickness of the intermediate magnesium sulfate-containing LDPE layer 2 are 20 μm and 30 respectively.
Three-layer inflation in the same manner as in (A), except for μm
Film produced and coated with polyvinylidene chloride on a biaxially stretched polypropylene film, Senen KOP # 20 manufactured by Taisel Chemical Co., Ltd.
The film layer (thickness 20 μm) 10 is laminated to prepare a KOP coat laminating film 11 (FIG. 6) having a thickness of 80 μm.
0 × 200 × 0.08 mm) was produced.

The moisture absorption repeating test in the bag shown in (A), (B) and (C) above was conducted at 25 ° C., and the results of the respective humidity control functions are shown in FIGS. 7, 8 and 9, respectively. Indicated. For comparison, a commercially available product for comparison, that is, a commercially available 0.06 mm-thick plastic bag for the bag (A), and a commercially available aluminum coat bag (( The same test was performed on the commercially available 0.06 mm thick polybag for the bag of C), and the results are also shown in FIGS. 7, 8 and 9, respectively.

As is clear from the results shown in FIGS. 7, 8 and 9, in the repeated moisture absorption test, the product of the present invention was not tested in any of the above cases (A), (B) and (C). It showed humidity control function while retaining humidity, but the commercial product for comparison did not show humidity control function.

Further, as described above, it is understood that the equilibrium humidity can be changed and the humidity control function can be controlled by changing the resin to be kneaded. In addition, the above (A),
As in the case of (B) and (C), by changing the amount of the layer in which magnesium sulfate is kneaded and the outer layer,
Some control of the humidity control function is possible.

Further, magnesium sulfate is kneaded into low-density polyethylene as in (A) above, and is kneaded into ethylene-methyl acrylate copolymer as in (B) above. Since the resin has a lower water vapor transmission rate than that of (A), the equilibrium humidity of (A) is higher than that of (B). In the case of (B), since the kneaded resin is an ethylene-methyl acrylate copolymer, which has a high moisture permeability, the equilibrium humidity is lower than that of (A) as described above. Like the one in C),
Even if the same resin as (A) is kneaded, the equilibrium humidity will be slightly different depending on the change in the layer structure.

As described above, by changing the combination of magnesium sulfate and the resin, it is possible to obtain a humidity control film having various humidity control functions with different equilibrium humidity.

Example 4 100 parts by weight of the low-density polyethylene used in Example 3 and 50 parts by weight of anhydrous magnesium sulfate used in Example 1 were kneaded by the kneading extruder used in Example 1, and then hot. Pellets were prepared by cutting, and pellets were similarly prepared from 100 parts by weight of the ethylene-methyl acrylate copolymer used in Example 1 and 100 parts by weight of anhydrous magnesium sulfate used in Example 1. An injection molding machine (PS-20E2VS manufactured by Nissei Plastic Industry Co., Ltd.)
E) was used to prepare two kinds of samples of the inner lid (diameter 9.2 mm, thickness 1 mm) of a 500 ml capacity wide-mouth container, and in order to investigate the humidity control function of each of these two samples,
Repeated tests of moisture absorption in a closed space in a wide-mouthed container were performed at 25 ° C., and the results are shown in FIG. For comparison, a general comparison product was also tested, and the results are also shown in FIG.

As is apparent from FIG. 10, the sample of the present invention has a humidity control power, but the general-purpose sample for comparison has no humidity control power at all. Example 5 Low density polyethylene manufactured by Sumitomo Chemical Co., Ltd. (trade name:
Sumikathene F411-1, Density 0.921 g / cm ³⁾
100 parts by weight and commercially available magnesium sulfate manufactured by Kanto Chemical Co., Ltd. (average particle size 60 μm, specific surface area 0.3 to 3.3 m)
50 parts by weight of ² / g) was kneaded by the kneading extruder used in Example 1, hot cut to prepare pellets, and a sheet having a thickness of 0.5 mm was formed by the T-die method. 50 mm × 50 mm × 0.5 mm) was produced.
Separately, the anhydrous magnesium sulfate (average particle diameter 4 μm, specific surface area 3.1 to 1.6 m ² / g) used in the present invention was used in the same manner as described above, and a sheet having a thickness of 0.5 mm was used.
A moisture absorption test was conducted under the atmosphere of a temperature of 25 ° C. and a relative humidity of 75% together with the above sheet. The results are shown in Fig. 11.

As is apparent from the results shown in FIG. 11, in the case of the sheet made of the former commercially available magnesium sulfate having a large average particle size of more than 30 μm, the latter of the present invention having a small average particle size of 30 μm or less. The moisture absorption rate is slower than the sheet produced using magnesium sulfate used in.
Further, after absorbing moisture, a microscopic photograph (magnification of 100) was taken on each sheet surface, the latter photograph of the product of the present invention is shown in FIG. 12, and the former photograph of the commercial product is shown. It is shown as FIG. The product sheet of the present invention in FIG.
In the case of G., the surface has not changed compared to before moisture absorption. On the other hand, the commercially available magnesium sulfate having a large particle size has a large variation in specific surface area, and the comparative sheet of FIG.
In this case, magnesium sulfate elutes and crystallizes after moisture absorption, causing expansion, shrinkage, and cracking of the molded product due to moisture absorption, and dimensional stability cannot be maintained, making it a practical molded product. Nakatsuta.

The anhydrous magnesium sulfate used in the present invention has a fine average particle diameter of 4 μm, and fine pores are formed in the particles, so that the stability of the molded product, the expansion, shrinkage, elution, cracking due to moisture absorption, etc. It was possible to produce a film, a sheet, and a molded product which did not occur and had a good humidity control function.

Example 6 A resin material for an upper layer in which the same weight of each of ethylene-vinyl acetate copolymer, polyethylene and calcium carbonate and the required amount of azoisobutyronitrile (foaming agent) were mixed, and ethylene-vinyl acetate copolymer Using a resin material for the lower layer in which the same weight of each of the polymer, polyethylene and anhydrous magnesium sulfate used in Example 1 and the required amount of the above-mentioned foaming agent are mixed, a blue (upper layer) and a white color are obtained by a kneading foam molding machine. It consists of two layers (lower layer) (both layers have the same thickness),
Two-layer foam product with closed cell structure [50 mm x 50 mm x 20
mm (thickness)] was obtained. Temperature 2 for this sample
5 ° C, relative humidity 75% and temperature 25 ° C, relative humidity 50%
The moisture absorption rate was measured under both conditions and the results are shown in Fig. 1.
Shown in FIG.

As is apparent from FIG. 14, the above foamed two-layer article had a high hygroscopic force. Further, this foamed two-layer product had a humidity control function because it required a long time to absorb moisture when the humidity was low and a short time to absorb moisture when the humidity was high.

Example 7 100 parts by weight of the low-density polyethylene used in Example 5 and 50 parts by weight of anhydrous magnesium sulfate used in Example 1 were kneaded by the kneading extruder used in Example 1, and then hot cut. A pellet having a thickness of 0.5 mm (50 mm × 50 mm × 0.5 mm) was produced by the T-die method. For comparison, 100 parts by weight of the above low-density polyethylene and magnesium sulfate pentahydrate (MgS
Pellets were prepared in the same manner as above from 50 parts by weight of O ₄ .5H ₂ O), and a sheet having a thickness of 0.5 mm similar to the above was prepared by the T-die method. Using these sheets as samples, a moisture absorption test was conducted under the conditions of a temperature of 25 ° C. and a relative humidity of 75%, and the moisture absorption rates were measured and compared. The results are shown in FIG.

From the results of FIG. 15, in the case of the sheet sample containing magnesium sulfate pentahydrate for comparison, as compared with the sheet sample containing anhydrous magnesium sulfate used in the present invention, It is clear that the rate of moisture absorption is slow.

A substance such as magnesium sulfate, which absorbs moisture as an anhydride of a salt becomes a hydrate, has a constant vapor pressure depending on the hydration state of the salt. This vapor pressure is
It tends to increase as the hydration stage progresses. Naturally, the vapor pressure of anhydrous magnesium sulfate is lower than the vapor pressure of pentahydrate. When both are placed in an environment of relative humidity of 75% and 25 ° C, they both start to absorb moisture quickly. However, the rate of moisture absorption of both is the difference between the partial pressure of water vapor in this environment and the vapor pressure of its own. It is decided by. If this difference is large, the moisture absorption rate will be fast, and if it is small, it will be slow. Therefore, the hygroscopic state is as shown in FIG. 15, and as described above, in the case of the sheet sample containing magnesium sulfate pentahydrate, in the case of the sheet sample containing anhydrous magnesium sulfate, Compared with this, the moisture absorption rate becomes slower.

In the case of anhydrous magnesium sulfate used in the present invention, when moisture absorption is started under constant temperature conditions, the moisture absorption rate decreases as the vapor pressure increases as the hydration stage progresses, as shown in FIG. It can be seen that such a moisture absorption curve is drawn and that it has a humidity control function while maintaining a constant humidity.

The magnesium sulfate pentahydrate for comparison, when it is kneaded with a resin in a kneading extruder, releases its own water of hydration when heated in the kneading extruder, which causes obstacles during production. Occurs, and it is not possible to obtain a humidity control composition capable of exerting an effective function, and even if an attempt is made to form a molded article such as a film, a sheet or a container from this composition, the humidity control with commercial value is obtained. A molded product could not be obtained.

[0043]

The humidity-controlling composition and the humidity-controlling molded article of the present invention have the following effects.

1) It has a function of keeping the internal humidity of a sealed container, bag or the like constant and keeping the contents at an appropriate humidity, that is, a humidity control function, and has an arbitrary constant within a range of humidity 60% to 10%. Keep in humidity.

2) Excellent stability and use as a humidity control agent because it has stable humidity control and water retention and does not cause liquefaction leakage or generation of water droplets due to corrosiveness, scattering, and moisture absorption and liquefaction phenomenon. Has the above safety. Therefore, it is possible to effectively prevent quality deterioration due to oxidation of the product.

3) At the time of use, it is not necessary to wrap it like a conventional desiccant, and when it is formed as a bag-shaped or container-shaped packaging material, the packaging material itself functions as a humidity control agent,
Since it exerts the same humidity control effect as above, it works extremely rationally.

4) The moisture absorption effect lasts for a long time.

5) It is easy to manufacture and process and has excellent industrial productivity.

6) It has a light-shielding property and an antistatic property.

7) The foamed moisture-conditioning molded article obtained as a foam is lightweight and has a higher hygroscopic effect because it has a moisture absorbing effect even inside the foam.

The humidity-controlling composition and molded article of the present invention having the above-mentioned effects are foods, pharmaceuticals, cosmetics, favorite products,
It is an epoch-making product that can be used as an excellent humidity control agent for quality protection in a wide range of fields such as precision machinery and machine parts.

[Brief description of drawings]

FIG. 1 is a curve diagram showing the humidity control functions of a sheet sample obtained in Example 1 of the present invention and a comparative plate sample for comparison.

FIG. 2 is a curve diagram showing the humidity control function of the sheet sample obtained in Example 2 of the present invention.

FIG. 3 is a curve diagram showing the humidity control function of another sheet sample obtained in Example 2 of the present invention.

FIG. 4 is an explanatory view showing the layer structure of a three-layer inflation film obtained in Example 3 of the present invention.

FIG. 5 is an explanatory view showing the layer structure of the Al co-traminate film obtained in Example 3 of the present invention.

FIG. 6 is an explanatory view showing the layer structure of the KOP co-traminate film obtained in Example 3 of the present invention.

FIG. 7 is a curve diagram showing the humidity control function of the bag of the present invention manufactured from the film shown in FIG. 4 and the bag of the commercial product for comparison in comparison.

FIG. 8 is a curve diagram showing the humidity control function of the bag of the present invention made from the film shown in FIG. 5 and the bag of the commercially available product for comparison in comparison.

9 is a curve diagram showing the humidity control function of the bag of the present invention made from the film shown in FIG. 6 and the bag of the comparative commercial product for comparison.

FIG. 10 is a curve diagram showing the humidity control functions of two samples of the inner lid of the wide-mouthed container obtained in Example 4 of the present invention and a comparative general product in comparison.

FIG. 11 is a curve diagram showing the humidity control functions of the sheet sample obtained in Example 5 of the present invention and a comparative sheet sample prepared by using commercially available magnesium sulfate.

FIG. 12 is a micrograph showing a crystal structure of a surface of a sheet sample obtained in Example 5 of the present invention after absorbing moisture.

FIG. 13 is a photomicrograph showing the crystal structure of the surface of the comparative sheet sample shown in Example 5 of the present invention after moisture absorption.

FIG. 14 is a curve diagram showing the results of a moisture absorption test on a foamed double-layered product sample obtained in Example 6 of the present invention.

FIG. 15 is a curve diagram showing the moisture absorption rates of the anhydrous magnesium sulfate-containing polyethylene sheet sample obtained in Example 7 of the present invention and the comparative magnesium sulfate pentahydrate-containing polyethylene sheet sample for comparison. ..

[Explanation of symbols]

1 ... HDPE layer, 2 ... Magnesium sulfate-containing LDPE
Layer, 3, 8 ... LDPE layer, 4 ... Three-layer inflation film, 5 ... Magnesium sulfate-containing EMA layer, 6 ... PE
T layer, 7 ... Al layer, 9 ... Al co-laminate film, 10 ... KOP layer, 11 ... KOP co-laminate film.

Claims (6)

[Claims] 1. The formula M is added to 100 parts by weight of the thermoplastic resin.
gSO ₄ · nH ₂ O (provided that 0 ≦ n ≦ 3) and an average particle diameter of 30 μm or less of magnesium sulfate 5 to
A humidity control composition containing 400 parts by weight. 2. When magnesium sulfate absorbs moisture, it first forms hexahydrate, and as the amount of moisture absorption increases, only hexahydrate increases. The humidity control composition according to claim 1, wherein the moisture control composition is changed to a heptahydrate when the water absorption rate becomes 43 to 48% at a low level. 3. The method according to claim 1, further comprising a foaming agent.
The foamable humidity control composition described. 4. A foaming and humidity-controlling molded article obtained from the foaming and humidity-controlling composition according to claim 3. 5. A film-like, sheet-like, bag-like, pellet-like or container-like humidity-conditioning molded article comprising the humidity-controlling composition according to claim 1 or 2. 6. A laminated humidity-conditioning molded article obtained by laminating at least one kind of humidity-controlling laminated material comprising the humidity-controlling composition according to claim 1 or 2.