KR100894629B1 - Desiccant Containing Indicator for Hygroscopic Level and Preparing Method Thereof - Google Patents

Abstract

The present invention relates to a desiccant comprising a hygroscopic indicator and a method for producing the same, wherein according to the present invention, methyl violet as a hygroscopic indicator is homogeneous on the surface of a porous desiccant such as silica, alumino-silicate, zeolite and montmorillonite. It is distributed so as to provide a desiccant comprising a moisture absorption indicator, the content of methyl violet is 0.0005 to 0.5wt% and the balance consists of the above-mentioned porous desiccant, and a manufacturing method thereof, and a desiccant comprising a moisture absorption indicator according to the present invention. Shows hygroscopicity indicator in acidic area, harmless to human body and environmentally friendly, and has good sensitivity to hygroscopicity. Chloride can be adjusted according to the various physical properties and forms of the desiccant. It can effectively replace the existing desiccant that used cobalt, especially the silica gel desiccant that uses cobalt chloride as an indicator, and if used in the form of card pulp or resin board or laminated on There is no fear of carelessness or food contamination by infants or children, and no children or infants can be mistaken for food and swallowed.

Silica gel, desiccant, moisture absorption, indicator, chromaticity

Description

Desiccant containing hygroscopic indicator and its manufacturing method {Desiccant Containing Indicator for Hygroscopic Level and Preparing Method Thereof}

The present invention relates to a desiccant including a hygroscopic indicator and a method for manufacturing the same, and more particularly, to a moisture absorbent or a deodorant porous of silica, alumino-silicate, zeolite and the like. The present invention relates to a porous desiccant imparting ability to give an indication capable of confirming the hygroscopicity of the desiccant by changing the chromaticity by coating or dipping an acid aqueous solution of an organic dye as an indicator, and a method of manufacturing the same.

In general, the desiccant or the desiccant is introduced into the food packaging container or the medicine packaging container to adsorb moisture in the gas in the container so that the produced product is kept constant below a predetermined moisture content standard during storage, distribution, or use, thereby deteriorating or deteriorating due to moisture. It is used for the purpose of maintaining the freshness, flavor, or chewing feeling as well as protecting the moisture, or for protecting moisture sensitive precision electrical and electronic products such as semiconductor chips and printed circuit boards from moisture. .

Various types of desiccants are currently known, and representative examples thereof include silica gel (SiO ₂ · H ₂ O), alumino-silicate beads, or clay such as montmorillonite. clay, zeolite as a molecular sieve (Na ₁₂ AlO ₃ SiO ₂ .12XH ₂ O), activated carbon, calcium oxide (CaO), calcium sulfate (CaSO ₄ ), and the like. .

Here, silica gel is an amorphous silica prepared from sodium silicate and sulfuric acid, and shows an excellent adsorption amount of about 40% relative to the weight of water. It is most widely used because it has the advantages of being corrosive, non-degradable, non-aqueous, easy to handle, inexpensive, and not causing pollution problems.

Montmorillonite or montmorillonite is a natural product of magnesium benzenite in the form of subbentonite after drying and is usually made of beads in the form of beads. The ability is also inferior to silica gel, but has the advantage of being the cheapest.

Zeolites have a microsphere structure of crystal network structure and have a very large specific surface area of 700 to 800 m2 per gram. Therefore, the zeolite does not release moisture to the product in the package due to the temperature increase such as silica gel or clay. It does not have the advantage of being relatively expensive.

Activated carbon has a very large specific surface area of about 200 to 1200 m2 per gram, which has excellent adsorption capacity, but it is not used as a desiccant for normal use due to product contamination.

Calcium oxide is an annealing or recalcinated type lime that has a water adsorption capacity of 28.5wt% or less, and is mainly used for dehumidifying food packaging of refrigerated or frozen foods because it has moisture adsorption capability at very low relative humidity. It is used.

Calcium sulfate, commercially known as Drierite, is made by dehydrating gypsum, is chemically stable, non-disintegrating, non-toxic and non-corrosive, and does not release moisture once adsorbed even at elevated temperatures. However, there is a disadvantage that the water adsorption capacity is as low as 10wt% is mainly used only in a limited range.

Among the various desiccants described above, silica gel is superior to other desiccants in terms of performance and cost, and thus is widely used not only in the packaging of food, medicine and various electronic products, but also in all industries, and is a high purity amorphous silicon dioxide (SiO ₂ ) molecule. Silica gel is composed of a large specific surface area, no chemical change, no solubility, no corrosion, water insolubility, and the particles are transparent, hard and colorless and odorless due to the well-developed pore structure inside the particles. As it is harmless to human body, it has excellent adsorption power to moisture and gas, does not change after moisture absorption, has high water resistance when used for industrial purposes, and has high stability due to low crushing rate when contacted with water.

On the other hand, various desiccants which have imparted moisture adsorption capability to the above desiccant have been conventionally proposed. The desiccant with the moisture adsorption indication removes moisture in the packaging of food or pharmaceutical packaging or precision electronics to maintain a dry state and the color change occurs as the moisture absorption of the desiccant increases. Can be used to easily determine the degree of moisture adsorption, or as an indicator of humidity change in a gas drying column, or as a moisture proof indicator for dehumidification, protection, and maintenance of transformer breathers, tank breathers, or electrical and electronic telecommunication systems. It is used widely or as a moisture proof indicator in the desiccator of a laboratory. It is reported that the desiccant having the water adsorption indication has a demand amount of about 3000 tons per year, and the demand is expected to increase according to the diversification and quality of life.

Conventionally, as a typical desiccant having a moisture adsorption indicator, a desiccant including a cobalt indicator has been widely used, for example, USP 2,460,071 (cobalt chloride containing desiccant), USP 2,460,069 (cobalt bromide containing desiccant), USP 2,460,073 ( Cobalt iodide desiccant), USP 2,460,074 (cobalt thiocyanate containing desiccant), USP 2,460,065 (cobalt sulfate containing desiccant), USP 2,460,070 (cobalt phosphate containing desiccant), etc. are mentioned.

       Desiccants containing the cobalt indicators described above generally have a color of blue at the time of absorbing moisture by impregnating a wetted silica gel or silica hydrogel with a cobalt halide solution to contain at least 0.5 wt% cobalt halide. It is prepared in the form of a blue anhydrous granular gel that turns pink.

       However, cobalt halides, in particular cobalt chloride, have been classified in the European Union as category II carcinogens (EEC Notice, 15/12/98), and from 1 July 2000 a new EU directive (Directive 98/98 / EC regulation) applies. The production and distribution of cobalt halides including cobalt chloride and products containing them, which are defined as potential carcinogens, are virtually prohibited.

In particular, considering that the target of injection of silica gel as a desiccant is food and medicine, it is expected that the use of cobalt halide worldwide will be banned in the future. Development is being requested.

Various techniques have been proposed to replace cobalt halide-containing desiccants at the request of the art.

USP 2,460,072 and USP 2,460,067 disclose copper (II) chloride and copper (II) bromide, respectively, but these compounds are potentially toxic and are not environmentally and humanly friendly and therefore desiccants in commercial food and pharmaceutical packaging. There is a problem that it is not suitable.

In addition, "Indicator properties of vanadium-modified silicas and zeolites" (Belotserkovskaya et al., Zh. Prikl. Khim. (Leningrad), 63 (8), 1674-9), "Synthesis and study of physicochemical properties of vanadium-containing silica-a humidity indicator "(Malygin, AA, Sb. Nauch. Tr. VNII Lyuminoforov I Osobo Chist. Veshchestv, 23, 24-8) and" Study of properties of vanadium-containing silica gel "(Malygin, AA et al. , Zh. Prikl. Khim. ( Leningrad), 52 (9), 2094-6) , the vanadium compound VOCl _3, when the humidity is increased to be impregnated into the silica gel as according colorless to yellow, orange, and again, gradually turned into red after Next, it is reported that the color finally shows brown color change. However, VOCl ₃ has a serious problem of being corrosive and toxic and difficult to manufacture or handle.

In addition, Korean Patent No. 676,777 discloses a desiccant for protecting a semiconductor chip or a printed circuit board. The indicator selected from thymol blue, methyl red, methyl orange, methyl red, neutral red, and aniline blue is dissolved in ethyl alcohol. Although a caustic soda solution and a cobalt-free humidity indicator solution containing a deliquescent metal chloride and an organic polymer compound are proposed, there is a problem that it is not suitable for use in food or pharmaceutical containers because caustic soda and metal chlorides are included.

In addition to the foregoing, methods for using various organic dyes and other inorganic compounds have been proposed to represent chromaticity changes with hygroscopicity as a conventional attempt to replace cobalt halides, in particular cobalt chloride, but these desiccants are safe. There is a problem that the indicator color is blue-based and the indicator color indicating a red color does not show a color change similar to the conventional cobalt chloride-containing desiccant corresponding to an accident deeply imprinted on the general consumer and trader.

Specifically, as a desiccant having a humidity indication to replace a cobalt chloride-containing desiccant, for example, a desiccant using phenolphthalein (discoloration point pH 8.3 to 10.0) changes color from yellow to colorless with increasing humidity. Using methyl orange (color change point pH 3.1-4,4), neutral red (color change point pH 6.8-8.0), thymol blue (color change point pH 6.0-7.6), or phenol red (color change point pH 6.8-8.4) The desiccant shows a change in chromaticity from red to orange and is not suitable as a desiccant with a humidity indication without rejection.

On the other hand, bromothymol blue (discoloration point pH 6.0 to 7.6), litmus (discoloration point pH 5.0 to 8.0), and bromophenol blue (discoloration point pH 3.0 to 4.6) change color from blue to red according to moisture absorption. Although there are advantages to be shown, these desiccants have a problem that the discoloration sensitivity is not sensitive when absorbing because the discoloration range is from neutral to weakly acidic or acidic regions.

In addition, referring to the shape of the desiccant having the humidity indicator, it is conventionally molded in the form of beads (beads), and then used in the pack, so that when the pack is torn by the carelessness of the user or children Even if not, depending on the type of products still be contaminated by beads, children or infants may be mistaken for food and swallowed.

Therefore, the first object of the present invention is to provide a desiccant including a hygroscopic indicator that is harmless to the human body and environmentally friendly.

A second object of the present invention is to provide a desiccant including a hygroscopic indicator which is markedly changed in chromaticity due to moisture absorption from a blue series to a red series, has a good sensitivity to moisture absorption, and exhibits a stable indicator.

A third object of the present invention is to provide a desiccant comprising a moisture absorption indicator of a new type in which the desiccant according to the first and second objects of the present invention is formed into a pulp paper or a resin board in the form of a card.

A fourth object of the present invention is to provide an effective method for preparing a desiccant according to the first to third objects of the present invention described above.

According to one preferred aspect of the present invention for smoothly achieving the first and second objects of the present invention, methyl violet as a moisture absorption indicator is homogeneously distributed on the surface of the porous desiccant, There is provided a desiccant comprising a moisture absorption indicator having a content of methyl violet of 0.0005 to 0.5 wt%, preferably 0.01 to 0.2 wt%, specifically 0.01 to 0.1 wt%, the balance being made of a porous desiccant.

According to another preferred aspect of the present invention for smoothly achieving the first and second objects of the present invention, the porous desiccant is silica, alumino-silicate, zeolite. There is provided a desiccant comprising a moisture absorption indicator, which is at least one selected from the group consisting of montmorillonite.

According to a preferred aspect of the present invention for smoothly achieving the third object of the present invention, 10 to 80 wt%, preferably 20 to 70 wt% of the desiccant, but not particularly limited to 35 to 55 wt% In the present invention, there is provided a desiccant comprising a moisture absorbing indicator molded or laminated on a pulp paper or a resin board composed of pulp or synthetic resin 20 to 90 wt%, preferably 30 to 80 wt%, and particularly 45 to 65 wt%.

According to a preferred aspect of the present invention for smoothly achieving the fourth object of the present invention described above, (A) 0.0005 to 0.5wt%, preferably 0.01 to 0.2wt% of methyl violet as a moisture absorption indicator based on the total weight of the composition. In particular, 0.01 to 0.1wt% dissolved in an acid solution to prepare a coating solution adjusted to pH 0.5 to 1.5, (B) a porous desiccant is deposited or spray coated in the coating solution to homogeneously distribute on the surface of the porous desiccant Provided is a method for producing a desiccant including a moisture absorption indicator comprising a coating step, and (C) a drying step.

According to another preferred aspect of the present invention for smoothly achieving the fourth object of the present invention described above, 10 to 80 wt%, preferably 20 to 70 wt% of the desiccant coated with the moisture absorption indicator, but not particularly limited thereto. Is mixed with 35 to 55 wt%, 20 to 90 wt% of pulp or synthetic resin, preferably 30 to 80 wt%, and particularly 45 to 65 wt%, and then made into pulp paper by papermaking and drying or by molding after melting the resin. Provided is a method of manufacturing a moisture-proofing agent including a moisture absorption indicator produced in the form of a resin board or laminated thereon.

The desiccant including the hygroscopic indicator according to the present invention exhibits hygroscopicity indicating ability in the acidic region, is harmless to the human body, environmentally friendly, and has a good sensitivity to hygroscopicity, resulting in a clear color change from blue to red based on moisture absorption. In addition, it exhibits stable indication and can adjust the point of change of chromaticity according to various physical properties and forms of the desiccant used. Therefore, the conventional desiccant using cobalt chloride, in particular, the conventional silica gel desiccant using cobalt chloride as an indicator It can be effectively replaced, and optionally used in the form of card pulp or resin board, or laminated on it, there is no user's carelessness or the risk of food contamination by infant or child, There is no fear of swallowing.

      Hereinafter, the present invention will be described in detail.

      Desiccant comprising a moisture absorption indicator according to the present invention is a moisture absorption indicator is composed of 0.0005 to 0.5wt% methyl violet (Methyl Violet) showing the indication in the acidic region and the remainder of the porous desiccant, the content of the methyl violet Preferably 0.01 to 0.2wt%, specifically 0.01 to 0.1wt% may be uniformly distributed on the surface of the porous desiccant by dipping or spray coating.

As the moisture absorption indicator to be applied to the moisture absorbent including the moisture absorption indicator according to the present invention, methyl violet, Mauveine, Tetrabromo Phenol Blue, which show color change from blue to red , Bromothymol blue, litmus, etc. are considered, but since the discoloration range of the indicator except for methyl violet ranges from a neutral region to a slightly acidic or acidic region, there is a problem that the discoloration sensitivity is not sensitive to moisture absorption, and applied to a desiccant. Tests have found that mobain, tetrabromo phenol blue, bromothymol blue, and litmus are not satisfactory enough to produce a distinct color change from blue to red desired to be obtained from the color change, whereas methyl violet Since blue and violet showed a clear and vivid color change, In the present invention, methyl violet was selected as the moisture absorption indicator.

As the porous desiccant in the desiccant including the moisture absorption indicator according to the present invention, silica, alumino-silicate, zeolite, montmorillonite, activated carbon , Calcium oxide (CaO), calcium sulfate (CaSO ₄ ), calcium chloride, or mixtures thereof, and preferably, silica gel, alumino-silicate beads, and zeolites. And most preferably silica gel, which is advantageous in terms of performance characteristics, safety, and cost considerations as a desiccant, and is most widely used.

Porous desiccant, such as silica gel, alumino-silica gel or zeolite, has a pH of less than 4.5, preferably 0.0005 to 0.5 wt%, preferably 0.01 to 0.2 wt%, and specifically 0.01 to 0.1 wt% of methyl violet organic dye. Desirably, the desiccant including a hygroscopic indicator prepared by coating or immersing an acid aqueous solution of pH 0.5 to 1.5 and then drying shows a very distinctly changeable chromaticity change at a relative humidity of 20 to 30%.

      On the other hand, when referring to the form of the moisture-proofing agent comprising the moisture-absorbing indicator according to the present invention, although the powder form is also possible, it is molded into a conventional bead shape with an average diameter of 20 ~ 300㎛ and the breathable pack It can be used in a general form to accommodate, optionally, the above-mentioned desiccant in the range of 0.5 ~ 200㎛ average diameter and then mixed with pulp or synthetic resin to be formed into a pulp paper or resin board form or laminated on it It may be.

      In this case, the amount of the desiccant including the moisture absorption indicator is 10 to 80 wt%, preferably 20 to 70 wt%, although not limited to 35 to 55 wt%, and the amount of pulp or synthetic resin is 20 to 90 wt%. It is preferably 30 to 80 wt%, and specifically 45 to 65 wt%.

      Desiccant comprising a moisture absorption indicator according to the invention can be prepared via the following steps.

      (A) 0.0005 to 0.5 wt%, preferably 0.01 to 0.2 wt%, and specifically 0.01 to 0.1 wt% of methyl violet as a moisture absorption indicator based on the total weight of the composition is dissolved in an aqueous acid solution to pH 4.5 or less, preferably preparing a coating solution adjusted to a pH of 0.5 to 1.5;

      (B) a coating step of homogeneously distributing the porous desiccant on the surface of the porous desiccant by dipping or spray coating the porous desiccant; And

      (C) drying step.

      In step (A), an acid is added to an aqueous organic dye indicator solution of methyl violet to prepare an acid aqueous solution (hereinafter referred to as "coating liquid") adjusted to pH 4.5 or lower, preferably pH 0.5 to 1.5.

The acid for preparing the above-mentioned acid aqueous solution is not particularly limited as long as it can be used with a selected organic dye indicator to form an acid of the aqueous solution. However, sulfuric acid, hydrochloric acid, acetic acid, benzoic acid, formic acid, chloroacetic acid and nitric acid are suitably used. Nitrous acid, phosphoric acid, tartaric acid, succinic acid, citric acid, maleic acid, or fumaric acid alone or a mixed solvent thereof may be used.

Here, suitably, a coating aid may be included in the acid solution so that the acid solution of the organic dye indicator can be wetted evenly with the porous desiccant. Examples of the coating aid include, for example, alcohols, In particular, ethanol may be included, but the present invention is not limited thereto, and any polar solvent which may help to improve coating dispersibility and does not react with a moisture absorption indicator is not particularly limited.

In the step (B) described above, the coating solution is wetted on the surface of the porous absorbent by dipping or coating the porous absorbent in the acid aqueous solution prepared above. Immersion or coating can generally be carried out at room temperature.

On the other hand, in the step (B) described above, a porous desiccant saturated with steam may be used to avoid the phenomenon of splashing during impregnation or coating of the porous desiccant. When the porous desiccant is directly immersed or coated in the coating solution, the particle size is slightly reduced.

In step (C), the coating solution is wet with a desiccant, and then dried, and dried at about 200 ° C. or less for 1 to 10 hours.

On the other hand, if the absorbency during use to change the chromaticity of the moisture absorbent indicator re-dried to the original state, it retains the hygroscopicity indicator ability to reuse.

Since the porous desiccant including the hygroscopic indicator according to the present invention has the hygroscopicity indicator in the acidic region, the color change occurs from blue to purple while changing from the acidic region to the neutral region according to the moisture absorption amount. .

In the case of the desiccant manufactured in various forms and properties such as silica gel, the point of change of chromaticity can be optimally controlled by precisely adjusting the pH and the amount of the indicator of the organic dye indicator aqueous solution (methyl violet aqueous solution) according to the physical properties. .

The desiccant including the hygroscopic indicator according to the present invention shows a visually identifiable change in chromaticity at a relative humidity of 10% or more, and a change in chromaticity becomes apparent at a relative humidity of 20% or more and a clear color change that is clearly distinguished at 30% or more. . When methyl violet is used as an organic dye indicator, the color becomes violet (purple) when absorbed from blue when dried.

On the other hand, the desiccant including the hygroscopic indicator according to the present invention may be prepared in the form of pulp paper or resin board or laminated on it, in which case the content of the desiccant is not limited but 10 to 80wt%, preferably 20 to 70 wt%, specifically 35 to 55 wt%, and the content of pulp or synthetic resin is not limited but is 20 to 90 wt%, preferably 30 to 80 wt%, and specifically 45 to 65 wt% based on dry weight.

First, when produced in the form of pulp paper or laminated thereon, pulp paper as a backing substrate may be a smooth paper or a pulp mold.

When the pulp paper is a general smooth paper, the following steps may be further performed.

(D1) The moisture absorbent coated with the moisture absorption indicator via step (B) described above is sprayed onto at least one area on at least one surface on a smooth paper coated or attached with an adhesive layer or a double-sided adhesive tape (spraying on the adhesive layer) step). Subsequently, (D2) the drying layer is transferred to a drying booth, for example, by drying means such as a hot air tube, an infrared heater, or the like, followed by drying at 0.5 ° C. or lower, preferably 70 ° C. to 80 ° C. for 0.5 to 4 hours, and at the same time, the desiccant is dried. By drying, the desiccant is permanently fixed on the smooth paper (curing and drying step). Optionally, (D3) the masking means is removed if a masking process for forming a specific pattern is performed. (D4) The excess desiccant not adhered to the smooth paper is then swept off by brush roller or air blowing (e.g., air cleaning for 30-50 seconds at an air pressure of 5-7 kbar) and then recovered with a recovery hopper ( Cleaning step).

The kind of the adhesive layer is not particularly limited as long as it can faithfully perform the role of permanent fixation, but may be any of those based on an aqueous acrylic copolymer or a polyurethane-based polymer, and cationic commonly used in the field of binders. , Anionic or nonionic pigments, wax oils and the like. In addition, although the above-mentioned hardening thickness of an adhesive layer is not restrictive and arbitrary in this invention, it is generally 30-300 micrometers thick, Preferably it is 50-150 micrometers thick, More preferably, it is 90-120 micrometers thick.

When the pulp paper is a pulp molding, the following steps may be further performed.

(E1) performing a step of mixing and papermaking the desiccant coated with the hygroscopic indicator via step (B) above and dissociated into the dissolved pulp liquid, and then (E2) transferring it to a drying booth and drying means as described above. By means of drying at 200 ° C. or lower, preferably 70 to 80 ° C. for 0.5 to 4 hours, or drying at room temperature for 1 to 2 days to obtain a pulp molding having a desiccant fixed in a pulp molded product shaped into a smooth paper or a specific shape. .

In addition, in the case of manufacturing in the form of a synthetic resin board or laminated thereon, (F1) melted synthetic resin such as polyethylene, polypropylene, polyurethane, etc. Spray desiccant with hygroscopic indicator (dehumidifier spreading step) and (F2) to harden so that the desiccant is fixed on at least one surface of the board (curing step), or optionally (G1) molten polyethylene, polypropylene, poly The desiccant including the moisture absorbent indicator via the above-mentioned step (B) may be mixed (synthetic desiccant mixing step) to the synthetic resin such as urethane, and the like (G2) may be performed by extruding onto a board (curing step).

The thickness of the above pulp paper or resin board is not limited in the present invention, but may be about 0.1 to 0.5 mm in thickness.

Hereinafter, the present invention will be described in more detail with reference to Examples, Comparative Examples, and Test Examples, which are intended to illustrate the present invention, but are not intended to limit the scope of the present invention, and the present invention is not limited thereto.

Example 1 Preparation of Desiccant with Methyl Violet

Methyl violet was used as a moisture absorption indicator in porous silica gel having an average particle diameter of 150 μm. A solution consisting of 0.05 wt% methyl violet, 0.5 wt% H 2 SO 3 and 5 wt% alcohol was immersed in silica gel at room temperature to be wetted, and then dried at 150 ° C. for 2 hours 30 minutes.

The silica gel absorbent thus prepared changed to violet (purple) when absorbed in blue during drying.

Comparative Example 1: Preparation of Mauveine-containing desiccant

Mauveine was used as a moisture absorption indicator in porous silica gel having an average particle diameter of 150 μm. A solution consisting of 0.05 wt% of mobine, 0.5 wt% of H 2 SO 3 and 5 wt% of alcohol was immersed in silica gel at room temperature to be wetted, and then dried at 150 ° C. for 2 hours and 30 minutes.

The silica gel absorbent thus prepared changed from red to dry when it was absorbed to blue.

Comparative Example 2: Preparation of Desiccant with Tetrabromophenol Bul

Tetrabromo Phenol Blue was used as a hygroscopic indicator in porous silica gel having an average particle diameter of 150 μm. First, a solution consisting of 0.05 wt% of tetrabromophenol bulru, 0.5 wt% of H 2 SO 3 and 5 wt% of alcohol was immersed at room temperature to be wetted, and then dried at 150 ° C. for 2 hours and 30 minutes.

The silica gel absorbent thus prepared changed from yellow to dry when it was hygroscopic.

Example 2: Preparation of desiccant pulp paper (smooth paper) containing methyl violet

The moisture absorbent coated with the moisture absorbent indicator prepared in Example 1 was sprayed onto a pulp paper coated with an epoxy adhesive layer in a rabbit shape to jump to a partial region on one surface, and dried at 150 ° C. for 2 hours and 30 minutes to cure the adhesive layer. Was permanently fixed to the pulp paper in a specific pattern and the desiccant was sufficiently dried. The weight of the desiccant was 42 wt% and the weight of the pulp paper was 58 wt%.

The pattern of the prepared pulp paper changed to violet (purple) when absorbed in blue when dried.

Example 3: Preparation of desiccant pulp paper (pulp molding) containing methyl violet

A moisture-proof indicator coated with a moisture absorbent prepared in Example 1 (60 wt% on a dry weight basis) was mixed with kraft pulp beating solution (40 wt% on a dry weight basis) and papermaking to prepare a smooth pulp molding having a thickness of 3 mm, and then 150 ° C. After drying for 2 hours and 30 minutes, the paper was made into a board shape to fix the desiccant in the pulp molding, and the desiccant was sufficiently dried.

The pulp molded product was changed to violet (purple) when absorbed in blue when dried.

Example 4 Preparation of Desiccant Synthetic Resin Board Including Methyl Violet

The moisture absorbent coated with the moisture absorbent indicator prepared in Example 1 was sprayed onto a synthetic resin board coated with an epoxy adhesive layer in a shape of a portion on one surface thereof, dried at 110 ° C. for 2 hours and 30 minutes to cure the adhesive layer, thereby specifying the desiccant beads. The desiccant was permanently fixed to the pulp paper as a pattern and the desiccant was sufficiently dried. The weight of the desiccant was 62wt% and the weight of the synthetic resin was 38wt%.

The pattern on the synthetic resin board was changed to violet (purple) when absorbed in blue when dried.

Example 5 Preparation of Desiccant Synthetic Resin Board Including Methyl Violet

A moisture-repellent indicator coated in Example 1 is coated with a desiccant (68 wt% by dry weight) and polyethylene resin (32 wt% by dry weight), melted and extruded to prepare a smooth synthetic resin board having a thickness of 2 mm Then, the desiccant was fixed in a polyethylene resin board by drying at 80 ° C. for 2 hours and 30 minutes, and the desiccant was sufficiently dried.

The produced polyethylene resin board was changed to violet (purple) when absorbed in blue during drying.

Test Example: Changes in Hygroscopicity and Chromaticity According to Relative Humidity

The moisture content and chromaticity change according to the humidity change of the desiccant of Examples 1 to 5 and Comparative Examples 1 and 2 were measured and observed, and the results are shown in Table 1 below.

Relative Humidity% 10 20 30 50 90 Chromaticity change Example 1 Silica gel 5.8 11.0 14.2 29.5 42.0 blue → violet Example 2 Silica Gel Adhesive Smooth Paper 6.2 11.3 14.8 31.4 48.6 blue → violet Example 3 Pulp moldings with silica gel 5.1 10.5 13.1 26.4 37.1 blue → violet Example 4 Silica gel adhesive resin board 4.9 9.8 12.2 21.8 34.6 blue → violet Example 5 Silica Gel Mixed Resin Board 5.8 11.0 14.2 29.5 42.0 blue → violet Comparative Example 1 Silica gel 5.5 10.5 13.5 28.5 41.5 red → blue Comparative Example 2 Silica gel 5.4 10.3 13.0 27.9 40.0 yellow → blue

In Table 1, the numerical values of Example 1 and Comparative Examples 1 and 2 represent the moisture content%.

In Examples 1 to 5, the change in chromaticity according to the hygroscopicity was found to be distinguishable from 10% relative humidity, and the change in chromaticity was apparent at a relative humidity of 20% or more and clearly distinguished at 30% or more. On the other hand, in Comparative Examples 1 and 2, the visual observation was not easy due to the change in chromatic color faded at 10% relative humidity, and only 30% of the color change could be detected.

In addition, in the case of Examples 1 to 5, when the hygroscopic agent causing the color change was re-dried at 150 ° C. for 2 hours and 30 minutes, the color was reduced to the original color.

Claims (14)

Methyl violet as a moisture absorption indicator is homogeneously distributed on the surface of the porous desiccant, The content of methyl violet is 0.0005 to 0.5wt% and the balance is composed of porous desiccant. Desiccant with moisture absorption indicator. The method of claim 1, wherein the porous desiccant is at least one desiccant selected from the group consisting of silica, alumino-silicate, zeolite, montmorillonite. Desiccant with moisture absorption indicator. The desiccant according to claim 1, wherein the desiccant including the moisture absorption indicator is in the form of pulp paper or synthetic resin board. The desiccant according to claim 1, wherein the desiccant including the moisture absorption indicator is spray-cured and fixed on at least a portion of the adhesive layer applied on at least a portion of the pulp paper or the extruded synthetic resin board. The desiccant with moisture absorption indicator according to claim 3 or 4, wherein the desiccant has a weight of 10 to 80 wt% and the pulp or synthetic resin has a weight of 20 to 90 wt%. Method for producing a desiccant comprising a moisture absorption indicator consisting of the following steps:        (A) dissolving 0.0005 to 0.5 wt% of methyl violet as a moisture absorption indicator based on the total weight of the composition in an acid aqueous solution to prepare a coating solution adjusted to pH 0.5 to 4.5 or less;        (B) a coating step of uniformly distributing the porous desiccant to the surface of the porous desiccant by dipping or spray coating the above-mentioned coating solution, and        (C) drying step of drying the coated porous desiccant. 7. The acid according to claim 6, wherein the acid used in the preparation of the aqueous acid solution is selected from the group consisting of sulfuric acid, hydrochloric acid, acetic acid, benzoic acid, formic acid, chloroacetic acid, nitric acid, nitrous acid, phosphoric acid, tartaric acid, succinic acid, citric acid, maleic acid, and fumaric acid. The manufacturing method of the desiccant containing moisture absorption indicator which is at least 1 sort (s) of solvent. The method of claim 7, wherein the acidic aqueous solution includes ethanol as a coating aid. 7. The adhesive layer according to claim 6, wherein the desiccant coated with the moisture absorption indicator is sprayed on at least one area on at least one surface on a smooth pulp paper coated or attached with an adhesive layer or a double-sided adhesive tape following step (B). A method for producing a desiccant including a hygroscopic indicator after performing the step of spraying on, followed by the drying step of (C). 10. The method of claim 9, wherein the area to which the adhesive layer or the double-sided adhesive tape is not applied or adhered is masked and the masking is removed after the drying step. The method according to claim 6, wherein the step (B) is followed by the step of mixing and papermaking the desiccant coated with the moisture absorption indicator via step (B) and dissociating it into the dissolved pulp liquid. The manufacturing method of the desiccant containing a moisture absorption indicator. 7. The method of claim 6, wherein the desiccant coated with the moisture absorption indicator via step (B) is sprayed when the molten synthetic resin is extruded onto the board, and cured to fix the desiccant on at least one surface of the board. Method for producing a desiccant containing a moisture absorption indicator to perform. The method of claim 6, wherein the moisture-absorbing agent coated with the moisture-absorption indicator via step (B) is mixed in a molten synthetic resin, extruded onto a board, and cured. The content of the desiccant including the moisture absorption indicator is 10 to 80 wt% based on dry weight, and the content of pulp or synthetic resin is based on dry weight. The manufacturing method of the desiccant containing 20 to 90 wt% of a moisture absorption indicator.