Patent Application
20240226805
The present disclosure relates to a humidity control material, and a humidity control material with a packaging material. The present application claims priority from Japanese Patent Application No. JP2021-085885, filed on May 21, 2021, and Japanese Patent Application No. JP2021-156223, filed on Sep. 27, 2021, the contents of which are hereby incorporated by reference into this application.
Humidity control materials have a higher humidity control capability in a wide humidity range from a low to a high than widely used desiccants made of, but not limited to, B-type silica gel. Humidity control materials can be thus utilized in extensive use applications.
Patent Literature 1 discloses a hygroscopic composition containing at least one of sodium acetate and potassium acetate, as well as a water absorbing binder, wherein the ratio between the total amount of the sodium acetate and potassium acetate (Ac) and the amount of the water absorbing binder (B), Ac:B [mass ratio], ranges from 2:3 to 4:1. Accordingly, sodium acetate and/or potassium acetate, both of which are non-halogen inorganic salts, can be used, thereby offering a hygroscopic composition that is inexpensive and has high hygroscopicity, and that has a low possibility of metal rust or other things and is thus highly safe.
It is unfortunately difficult to use conventional humidity control materials in a use application where exerting a high humidity control capability in a particular humidity range is important.
One aspect of the present disclosure has been made in view of this problem. One aspect of the present disclosure aims to offer a humidity control material that can be used in, for instance, a use application where exerting a high humidity control capability in a particular humidity range is important, and to offer a humidity control material with a packaging material that can be used in the foregoing use application.
A humidity control material according to one aspect of the present disclosure includes the following: a water absorber including a water absorbing material; and a humidity control ingredient contained in the water absorbing material, and configured to absorb or release moisture. The humidity control ingredient includes a metal salt having a deliquescence point falling within a relative humidity of 30 to 80% RH inclusive.
A humidity control material with a packaging material according to another aspect of the present disclosure includes the following: the humidity control material according to the one aspect of the present disclosure; and a packaging material having moisture permeability, and packaging the humidity control material.
The embodiments of the present disclosure will be described with reference to the drawings. It is noted that with regard to the drawings, identical or equivalent components will be denoted by the same signs, and the description of redundancies will be omitted.
A humidity control material 1 according to the first embodiment illustrated in
As illustrated in
The water absorber 11 and the water absorbing material 21 have a particulate shape. The water absorber 11 and the water absorbing material 21 have a diameter of, for instance, several millimeters to several tens of millimeters.
The water absorbing material 21 can chemically or physically absorb the component that deliquesces, and that is included in the humidity control ingredient 12. This can prevent syneresis of the deliquesced component from the water absorbing material 21 due to its separation from the water absorbing material 21. When the humidity control ingredient is a humidity control liquid, the water absorbing material 21 can be impregnated with the humidity control liquid. The water absorbing material 21 of 100 parts by weight is desirably impregnated with a humidity control liquid of 1 to 1000 parts by weight inclusive. Using a humidity control liquid impregnated in the water absorbing material 21 can increase the area of the interface between the humidity control ingredient and the air when compared to an instance where the humidity control liquid is used alone. This can accelerate the speed of humidity control.
The water absorbing material 21 includes at least one selected from the group consisting of a water absorbing resin and a clay mineral.
The water absorbing resin may be an ionic resin or a non-ionic resin.
The ionic resin includes at least one selected from the group consisting of, for instance, a polyacrylic alkali metal salt and a starch-acrylate graft polymer. The polyacrylic alkali metal salt includes sodium polyacrylate for instance.
The non-ionic resin includes at least one selected from the group consisting of, for instance, a vinyl acetate copolymer, a maleic anhydride copolymer, polyvinyl alcohol, and polyalkylene oxide.
The clay mineral includes at least one selected from the group consisting of, for instance, a silicate mineral and a zeolite. The silicate mineral includes at least one selected from the group consisting of, for instance, sepiolite, attapulgite, kaolinite pearlite, and dolomite.
The humidity control ingredient 12 includes a metal salt having a deliquescence point falling within a relative humidity of 30 to 80% RH inclusive. The metal salt desirably forms hydrate crystals within the relative humidity of 30 to 80% RH inclusive. Accordingly, the humidity control ingredient 12 has a threshold humidity within the relative humidity of 30 to 80% RH inclusive; the humidity control ingredient 12 can little absorb moisture when the relative humidity of the surrounding air is lower than the threshold humidity, and the humidity control ingredient 12 can absorb moisture when the relative humidity of the surrounding air is higher than the threshold humidity. The metal salt includes a carboxylate for instance. The carboxylate includes at least one selected from the group consisting of, for instance, sodium formate, sodium acetate, and sodium propionate.
The humidity control ingredient 12 may include another component different from the foregoing metal salts. For instance, the humidity control ingredient 12 may include an additive for regulating the foregoing threshold humidity. The additive includes at least one selected from the group consisting of, for instance, another metal salt different from the foregoing metal salts, a polyhydric alcohol, and a nucleation material of a hydrate crystal of the foregoing metal salt.
The other metal salt includes at least one of, for instance, lithium chloride, calcium chloride, magnesium chloride, sodium benzoate, lithium bromide, calcium bromide, potassium bromide, sodium lactate, potassium lactate, potassium acetate, lithium acetate, potassium formate, sodium butyrate, sodium citrate, potassium citrate, sodium chloride, and potassium carbonate.
The polyhydric alcohol includes at least one selected from the group consisting of, for instance, glycerin, propanediol, butanediol, pentanediol, trimethylolpropane, butanetriol, ethylene glycol, diethylene glycol, triethylene glycol, and lactic acid, and the polyhydric alcohol desirably includes a polyhydric alcohol having three or more hydroxyls. The polyhydric alcohol having three or more hydroxyls includes glycerin for instance. The polyhydric alcohol may constitute a dimer or a polymer.
The nucleation material includes at least one selected from the group consisting of a carboxylic acid having two or more carboxyl groups, and an amide having two or more amide groups.
The metal salt having a deliquescence point within the relative humidity of 30 to 80% RH inclusive has a threshold humidity constituting a boundary between a relative humidity at which moisture absorption cannot be performed substantially, and a relative humidity at which moisture absorption can be performed substantially. The relative humidity at which moisture absorption cannot be performed substantially is a relative humidity at which the metal salt forms, together with water molecules, firm hydrate crystals, and/or a relative humidity lower than a threshold humidity including a deliquescence point for deliquescence and liquefaction. The relative humidity at which moisture absorption can be performed substantially is a relative humidity higher than this threshold humidity. Further, the humidity control ingredient 12 has a threshold humidity constituting a boundary between a relative humidity at which moisture absorption cannot be performed substantially due to its metal salt, and a relative humidity at which moisture absorption can be performed substantially. The additive is a substance having hygroscopicity and high water solubility, and the additive changes the threshold humidity of the humidity control ingredient 12 from the threshold humidity of the metal salt. Thus, including an appropriate additive in the humidity control ingredient 12 can offer the humidity control material 1 having a threshold humidity suitable for a use application.
The content of the additive within the humidity control ingredient 12 is desirably 10 to 90 wt % inclusive. For an additive content smaller than 10 wt %, changing the threshold humidity of the humidity control ingredient 12 from the threshold humidity of the metal salt tends to be difficult. For an additive content greater than the 90 wt %, the threshold humidity constituting the boundary between the relative humidity at which moisture absorption cannot be performed substantially and the relative humidity at which moisture absorption can be performed substantially tends to be unclear.
As illustrated in
A carboxylate, in particular, a carboxylic-acid sodium salt hydrates and forms, together with water molecules, firm hydrate crystals. The formed firm hydrate crystals further hydrate, deliquesce and liquefy. However, large energy is necessary for the formed firm hydrate crystals to further hydrate. Hence, upon the relative humidity reaching a first relative humidity, a carboxylate hydrates and forms, together with water molecules, firm hydrate crystals, and upon the relative humidity reaching a second relative humidity higher than the first relative humidity, these hydrate crystals deliquesce and liquefy. For instance, as shown in
As such, a carboxylate, in particular, a carboxylic-acid sodium salt has a threshold humidity including such a relative humidity as to form, together with water molecules, firm hydrate crystals, and/or including such a deliquescence point that the hydrate crystals deliquesce and liquefy. Thus, for a carboxylate, in particular, a carboxylic-acid sodium salt, further moisture absorption than that for forming hydrate crystals together with water molecules does not advance when the relative humidity of the surrounding air is lower than its threshold humidity, and moisture absorption advances abruptly to thus raise its moisture absorption rate when the relative humidity of the surrounding air becomes higher than the threshold humidity. For instance, as shown in
As such, a carboxylate has a threshold humidity constituting a boundary between a relative humidity at which moisture absorption advances little, and a relative humidity at which moisture absorption advances abruptly. For instance, as shown in
The moisture absorption rate of a moisture absorbing ingredient having no threshold humidity, and the moisture absorption rate of a humidity control ingredient having no threshold humidity increase slowly along with rise in relative humidity. For instance, as shown in
Two or more kinds of carboxylates may be combined together and included in the humidity control ingredient 12. The foregoing additive may be included in the humidity control ingredient 12 to thus affect hydrate crystal formation, thereby regulating the threshold humidity and humidity control properties.
The foregoing threshold humidity enables the humidity control material 1 to be used in a use application where exerting a high humidity control capability in a particular humidity range is important. Further, the humidity control material 1 can be dried and renewed by low-temperature air having a relative humidity lower than the threshold humidity. That is, the humidity control material 1 does not require hot-air heating when it undergoes drying for renewal. For instance, when the humidity control ingredient 12 includes sodium formate as its base component, the humidity control material 1 can be dried and renewed by low-temperature air having a relative humidity lower than about 50 to 60% RH.
As described above, the moisture absorption rate of a humidity control ingredient having no threshold humidity increases slowly along with rise in relative humidity. Thus, equilibrium humidity changes greatly as a result of change in the moisture absorption rate of the humidity control ingredient, that is, change in the humidity control amount of moisture from the humidity control ingredient. For instance, as shown in
As such, around a threshold humidity, the humidity control ingredient 12 having the threshold humidity has a high humidity control effect and has a large humidity control amount of moisture. Thus, regulating the threshold humidity of the humidity control ingredient 12 around a humidity control target humidity enables the humidity control material 1 to condition the humidity of the surrounding air so as to maintain, for a long time, the relative humidity of the surrounding air at a relative humidity close to the humidity control target humidity.
As shown in
As shown in
Further, a comparison between
As shown in
In the manufacture of the humidity control material 1, the water absorber 11 is prepared, as illustrated in
The next is preparing a humidity control liquid 31, as illustrated in
The next is taking out the formed humidity control material 1 from the remaining humidity control liquid 31, as illustrated in
The humidity control material 1 has a high dew-condensation prevention effect. The humidity control material 1 is thus suitably used for preventing dew condensation that occurs, for instance, inside a transport container that is transported from a hot and humid region to a cold region. Such dew condensation tends to occur when goods, packing materials and others that are transported with a transport container contain a lot of moisture.
Reference is made to an instance where, as illustrated in
When the temperature rises during the daytime like this, the inside temperature of a transport container 41 rises as well. For instance, as illustrated in
When the temperature becomes low during the nighttime as time goes by, the temperatures of the ceiling surface 51 and a wall surface 54, both constituting the transport container 41, become low due to the radiation from the ceiling surface 51 and wall surface 54. This reduces the amount of saturated water vapor of the air around the ceiling surface 51 and wall surface 54. Accordingly, the inside absolute humidity of the transport container 41 becomes higher than the amount of saturated water vapor of the air around the ceiling surface 51 and wall surface 54. This causes dew condensation on the ceiling surface 51 and wall surface 54.
It is noted that this temperature fluctuation inside the transport container 41 increases along with approach to the ceiling surface 51. For instance, the temperature difference in the ceiling surface 51 between the daytime and nighttime is 29° C., the temperature difference in the middle air 52 between the daytime and nighttime is 19° C., and the temperature difference in the lower air 53 between the daytime and nighttime is 10° C.
When the humidity control material 1 containing the humidity control ingredient 12 including sodium formate as its base component, and having the moisture sorption isotherm shown in
To efficiently cycle the moisture absorption and renewal by a daily temperature cycle, the threshold humidity of the humidity control ingredient 12 is regulated so as to be higher than a daytime relative humidity. This can achieve high dew-condensation prevention effect.
Table 1 shows relative values of the amount of metal corrosion with regard to chloride-free CMA, a chloride-free acetic acid compound, chloride-free sodium formate, chloride-containing sodium chloride, chloride-containing calcium chloride, chloride-containing magnesium chloride, and a chloride-containing acetic acid compound. CMA stands for calcium magnesium acetate. A chloride-containing acetic acid compound is a mixture of a chloride-free acetic acid compound and sodium chloride.
Table 1 reveals that the amounts of metal corrosion of chloride-free CMA, a chloride-free acetic acid compound, and chloride-free sodium formate are significantly smaller than the amounts of metal corrosion of chloride-containing sodium chloride, chloride-containing calcium chloride, chloride-containing magnesium chloride, and a chloride-containing acetic acid compound.
Table 1 also reveals that the amount of metal corrosion of a chloride-containing acetic acid compound is smaller than the amounts of metal corrosion of chloride-containing sodium chloride, chloride-containing calcium chloride, and chloride-containing magnesium chloride.
As can be seen from the foregoing, the amount of metal corrosion of the humidity control ingredient 12 composed of a carboxylate, such as CMA, an acetic acid compound, or sodium formate, as its base component is smaller than the amount of metal corrosion of a humidity control ingredient composed of a chloride as its base component.
Thus, the humidity control material 1, which contains the humidity control ingredient 12 composed of a carboxylate as its base component, is less likely to cause metals or other things to rust and can be thus used in many use applications. For instance, the humidity control material 1 can be used in use applications, such as moisture-controlled storage of various metal-containing articles of taste, including musical instruments and cameras, and dew condensation prevention in the insides of electric boxes and transport containers.
The water absorber 11 illustrated in
The water absorber 11 illustrated in
The water absorber 11 illustrated in
The water absorber 11 illustrated in
The water absorber 11 illustrated in
A difference between a second embodiment and the first embodiment will be described. With regard to what will not be described, a configuration similar to the configuration applied in the first embodiment is applied in the second embodiment.
As illustrated in
The indicator 23 includes a pH indicator for instance. A pH indicator can be used as the indicator 23, because the pH of the humidity control ingredient 12 changes in accordance with the moisture content of the humidity control ingredient 12.
The pH indicator is at least one selected from the group consisting of, for instance, bromocresol green, methyl orange, methyl red, methyl purple, methylene blue, bromocresol purple, bromthymol blue, bromophenol blue, chlorophenol red, neutral red, phenol red, cresol red, curcumin, phenolphthalein, α-naphtholphthalein, thymolphtalein, and alizarine yellow.
The humidity control material 2 may contain two or more kinds of pH indicators. The two or more kinds of pH indicators are desirably pH indicators where displayed color changes in pH values different from each other. This can increase color change variations that are displayed by the humidity control material 2. Consequently, a moisture-controlled humidity can be checked more strictly.
A difference between a third embodiment and the first embodiment will be described. With regard to what will not be described, a configuration similar to the configuration applied in the first embodiment is applied in the third embodiment.
A humidity control material 3 according to the third embodiment illustrated in
When the relative humidity is lower than the threshold humidity, the carboxylate is crystalized, and the scented material 24 is incorporated in the crystals of the carboxylate. Thus, the scented material 24 is prevented from vaporizing from the humidity control material 3, and the scent is prevented from released from the humidity control material 3.
When the relative humidity is higher than the threshold humidity, the carboxylate's crystal structure is loosened, thus releasing the scented material 24 from the carboxylate. Thus, the scented material 24 vaporizes from the humidity control material 3, and the scent is released from the humidity control material 3.
This can provide the humidity control material 3 with the function of an aromatic agent whose aroma is triggered by a humidity change.
The scented material includes at least one selected from the group consisting of, for instance, acetylisoeugenol, acetyloeugenol, acetylcedrene, acetophenone, anise alcohol, anisaldehyde, anethole, allylamyl glycolate, allylionone, methyl anthranilate, benzyl benzoate, ionone, indole, eugenol, n-octanal, karon, camphor, benzyl cinnamate, geraniol, cedryl acetate, cinnamyl acetate, tricyclodecenyl acetate, phenylethyl acetate, o-t-butylcyclohexyl acetate, p-t-butylcyclohexyl acetate, benzyl acetate, amyl salicylate, cyclohexyl salicylate, sandalmysore core(2-methyl-4-(2,2,3-trimethyl-3-cyclopentene-1-yl)-2-butene-1-ol)), cis-3-hexenol, citral, citronellol, methyl dihydrojasmonate, dihydromyrcenol, terpineol, damaskone, thymol, decanal, δ-decalactone, γ-decalactone decyl aldehyde, terpineol, terpinene, n-nonanal, γ-nonalactone, methyl 2-nonenoate, bacdanol, pinene, phenylethyl alcohol, allyl phenoxyacetate, 1-(2-t-butylcyclohexyloxy)-2-butanol, flutate(ethyltricyclo[5.2.1.02,6]decane-2-ylcarboxylate), styrallyl propionate, benzyl propionate, n-hexanal, allyl hexanoate, α-hexyl cinnamic aldehyde, allyl heptanoate, heliotropin, benzyl alcohol, benzaldehyde, borneol, mylacaldehyde(4-(4-methyl-3-pentenyl)-3-cyclohexene-1-carboxaldehyde)), 4-methyl-3-decen-5-ol, ethyl 3-methyl-3-phenylglycidate, 3-methyl-5-phenylpentanol, ethyl 2-methylbutyrate, lime oxide, ethyl butyrate, ligustral(2,4-dimethyl-3-cyclohexenylcarboxaldehyde), linalool, limonene, styrax oil, tonka beans, pine oil, petitgrain oil, pepper oil, peppermint oil and rosemary oil.
A humidity control material 5 with a packaging material illustrated in
The humidity control material 61 is the foregoing humidity control material 1, 2, or 3.
The packaging material 62 has moisture permeability. The packaging material 62 packages the humidity control material 61.
Accordingly, the humidity control material 61 can be prevented from direct contact with a humidity control target object, and the humidity control material 61 can condition the moisture of the humidity control target object.
The packaging material 62 is a soft case being flexible and being in the form of a bag. The packaging material 62 may be a packaging material other than a soft case. An example of the packaging material other than a soft case is a box.
The packaging material 62 includes a moisture-permeable film 71 and a light-transparent film 72. The moisture-permeable film 71 has moisture permeability. An example of the moisture-permeable film 71 is a polyester non-woven textile. The light-transparent film 72 has light transparency. An example of the light-transparent film 72 is a polyethylene terephthalate film. The light-transparent film 72 allows the state of the humidity control material 61 to be visually observed. In particular, when the humidity control material 61 is the humidity control material 2 having an indication function, the color displayed in the indication function can be visually seen through the light-transparent film 72.
The packaging material 62 includes a front-surface material 81 and a back-surface material 82. In the fourth embodiment, the front-surface material 81 is the light-transparent film 72, and the back-surface material 82 is the moisture-permeable film 71. Only part of the front-surface material 81 may be the light-transparent film 72. The edge of the front-surface material 81 and the edge of the back-surface material 82 are welded together by a heat seal.
The present disclosure is not limited to the foregoing embodiments. The present disclosure may be replaced with a configuration that is substantially the same as the configurations described in the foregoing embodiments, with a configuration that substantially exerts the same action and effect as the foregoing configurations, or with a configuration that can substantially achieve the same object as the foregoing configurations.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-085885 | May 2021 | JP | national |
| 2021-156223 | Sep 2021 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2022/015795 | 3/30/2022 | WO |
