JP3176539B2 - Humidity control low density paper and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a humidity-controlling low-density paper mainly made of papermaking fibers, which has excellent moisture absorption / desorption performance and does not pollute the environment. More specifically, in a closed room, a lightweight material having a cushioning property capable of adjusting a change in indoor relative humidity (hereinafter referred to as humidity) caused by a temperature change in an external environment within a certain humidity range in a short time. The present invention relates to a low-density moisture-controllable paper which can be suitably used for a paper.

[0002]

2. Description of the Related Art Conventionally, low-density materials such as expanded polystyrene, expanded polyethylene, and expanded urethane have excellent heat insulation and heat retention, good moldability and low cost, and are used for heat insulation and cushioning. It has been widely used as a material and the like. However, these materials are inferior in natural decomposability,
In addition, there is a problem such as emission of pollutants and black smoke at the time of combustion, and in fact, it is difficult to dispose of it once disposed of. Therefore, the demand for more environmentally friendly materials is increasing. In addition, when the goods are packed with the above-mentioned materials and stored or transported, if the environment suddenly changes in temperature, dew condensation or stuffy phenomena occur in the package, which causes rust on the goods. There were problems such as generation of mold and mold.

[0003] Against this background, there have been proposed several attempts to replace paper with the above-mentioned materials by applying paper as an environmentally-friendly material, significantly improving heat insulation and cushioning properties at low density. For example, Japanese Patent Application Laid-Open No. 59-36800 proposes a method for producing low-density paper by blending polyester fibers. However, this method does not cause a significant decrease in density, and requires a large amount of chemical fibers to be incorporated. Since the effect is difficult to obtain, the obtained paper is close to synthetic fiber paper, and there is a problem that the original properties of the paper and the environmentally friendly properties are impaired.

As a method for obtaining low-density paper by blending hollow capsules, Japanese Patent Publication No. 52-39924 proposes a production method in which a shirasu balloon is internally added during papermaking. However, this method has a drawback that papermaking is difficult because the density difference between the shirasu balloon and the paper pulp is large, and the shirasu balloon floats on water.

On the other hand, foamable microcapsules which foam by heat are disclosed in US Pat.
No. 26524, JP-B-44-7344, etc., a foaming agent such as butane gas is contained in microcapsules such as a copolymer of methacrylic acid and styrene, a copolymer of acrylonitrile and styrene, and vinylidene chloride. Heating causes butane gas and the like to expand to form hollow resin spheres.

A method of producing a low-density material by applying a coating or ink mixed with these foamable microcapsules to paper, printing and stamping the paper, and heating the foam to foam the paper is also proposed. . For example, Japanese Patent Publication No. 53-31784
JP-A-54-31500, JP-A-62-2614
No. 36, Japanese Patent Application Laid-Open No. Hei 3-241099, and the like, proposals for the purpose of use as a material for wallpaper are made. These use foamable microcapsules for the purpose of imparting air permeability and unevenness, and are not intended to reduce the density of the entire paper.

[0007] Japanese Patent Application Laid-Open No. Hei 5-339898 proposes a method for producing a low-density paper by adjusting the water content of the paper before heating and foaming to 65 to 72% by weight. However, in this method, the moisture content of the wet paper before drying is much larger than the moisture content of the wet paper at the time of ordinary papermaking, so that special consideration is required in the drying step. In particular, as the density of the paper becomes lower due to foaming, heat insulating properties are developed, so that the drying efficiency is greatly reduced.

On the other hand, there have been proposed some attempts to impart humidity control performance to paper by using a moisture absorbing / releasing powder (hereinafter referred to as "humidifier"). For example, Japanese Patent Application Laid-Open No. 58-51921 discloses that a humidity control agent is made as fine as possible, and is applied to paper, cloth, nonwoven fabric, or the like together with a binder, or contained in paper to increase the surface area. A highly responsive humidity and humidity control sheet is disclosed. Further, Japanese Patent Application Laid-Open No. 2-80696 proposed by the present inventors discloses an article preservation which is excellent in both functions of humidity control and gas adsorption by using the above-mentioned humidity control agent and inorganic powder having gas adsorption performance in combination. Paper is disclosed. However, these papers and sheets are intended to contain only 20 to 80% by weight of inorganic powder and to mainly obtain only humidity control performance. In this case, in order to improve the humidity control performance, it was necessary to fill the inorganic powder, which is a humidity control agent, with a high density, and the paper was inevitably heavy and was difficult to handle.

[0009] For the packaging of fragile articles that do not like moisture, the above-mentioned synthetic resin is foamed in a sheet or molded article, and a desiccant is enclosed in the package. It responded to the storage of goods and the effect of moisture. However, when the articles are wrapped in such a method, the content of the desiccant is ubiquitous, so that the content may vary in a dry state or it may be difficult to maintain an appropriate humidity condition for the content. It became.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems. Specifically, it is an object to obtain a humidity-controlling low-density paper having the following characteristics. (1) To provide a lightweight material excellent in humidity control. (2) As a substitute for the conventional foaming resin cushioning material or heat insulating / heat insulating material, moisture absorbing / releasing powder (hereinafter referred to as "humidifying agent") is used to impart humidity control performance, and during storage and transportation. Protect the goods from rust and mold and provide eco-friendly materials with natural degradability.

[0011]

Means for Solving the Problems As a result of intensive studies, the inventors of the present invention have found that papermaking raw materials containing papermaking fibers as main materials include:
It has been found that the object to be solved by the present invention can be solved by blending a moisture absorbing / releasing powder and a foamable microcapsule to form a paper and then impregnating the paper with various impregnation liquids by a wet impregnation method. That is, the gist of the present invention is as follows: 10 to 88 parts by weight of papermaking fiber, 10 to 70 parts by weight of hygroscopic powder and 2 to 20 parts by weight of expandable microcapsules, and in some cases, 0 to 90 parts by weight of a binder.
２０20 parts by weight, and papermaking or papermaking, wherein the basis weight before drying is 50-100%
A paper binder of 0 g / m ² (in absolute dry basis weight) was mixed with a binder, and in some cases, an impregnating liquid in which foamable microcapsules were mixed and dispersed, with a wet impregnation method to obtain 5 parts of a papermaking raw material.
-40% by weight impregnation, followed by heating to expand the expandable microcapsules, having a density of 0.1-0.4
g / cm ^3, which is a method for producing a humidity-controlling low-density paper.

[0012] The humidity control performance referred to in the present invention is a property of maintaining a constant humidity in a closed container by quickly absorbing or releasing moisture against a temporary change in humidity caused by a rapid change in temperature. As a result, it is an object to keep the moisture content of the object to be preserved constant by keeping the humidity of the environment to be preserved constant. In addition, even in a container having poor airtightness, it also has an effect of reducing a bad influence on contents by making a sudden change in humidity gentle.

Next, the circumstances that led to the present invention will be described. The present inventors have disclosed in Japanese Patent Application No. 6-58155,
We have proposed a method to obtain low-density paper by mixing foamable microcapsules between paper layers by wet impregnation and heating and foaming them while the bond between pulp fibers is loose. In this wet impregnation method, the paper web is dewatered by press and then enters the impregnation step without drying. That is, since the paper used in the wet impregnation method does not yet have a bond between the pulp fibers in the impregnation step, the gap between the pulp fibers when immersed in the impregnation liquid is much larger than that in the dry impregnation method. Therefore, the infiltration of the foamable microcapsules into the inside of the paper layer can be performed uniformly and completely as compared with the dry impregnation method. As a result, when the material to be impregnated is extremely large, such as the foamable microcapsules used in the present invention, having a particle size of 5 to 30 μm as compared with the material used for ordinary impregnation processing, the impregnation into the paper layer can be prevented. The wet impregnation method is very effective in performing uniform impregnation, and low-density paper can be continuously and stably produced.

However, even with this method, penetration of the expandable microcapsules into the inside of the paper layer cannot be completely eliminated because the pulp fibers impair the filtration effect.
For this reason, as the paper web becomes thicker, the amount of the expandable microcapsules increases near the surface, and the amount of the expandable microcapsules decreases toward the inside, so that the density tends to be inclined in the thickness direction. The trend comes out.

[0015] Furthermore, in the case of a formulation having a high density as a raw material for papermaking, for example, when the fiber length of pulp is short, when the pulp has a high degree of beating, or when the formulation contains a large amount of an inorganic filler such as a humidifier, etc. Even in the wet impregnation method, a material having a large particle size, such as a foamable microcapsule, hardly penetrates freely between paper layers. As a result, the expansion ratio becomes lower, and the tendency to form a non-uniform expansion state increases.

To solve such a problem, the inventors of the present invention have conducted intensive studies. As a result, by mixing a paper with a foaming microcapsule together with a humectant to form a paper, hydrogen bonding between fibers is reduced. It has been found that an inhibitory effect is exhibited, and that the expandable microcapsules have an effect of promoting expansion when foamed. As a result, it has become possible to reduce the density even with high powder content paper.

Further, as a result of study by the present inventors,
It has been found that there is a close relationship between the voids of the low-density humidity control paper and the humidity control performance. More specifically, the low-density paper has a structure with very many voids and excellent air permeability. Therefore, the air easily passes through and easily comes into contact with the internally added humectant at that time, so that the humidity can be adjusted efficiently.

The present inventors have paid attention to the above facts and blended foamable microcapsules with papermaking raw materials to make paper.
The basis weight before drying with a water content of 50-60% by weight is 40-100.
By applying the wet impregnation method to a paper sheet of 0 g / m ² (in absolute dry basis weight), an impregnating liquid in which rubber latex and / or synthetic resin emulsion is mixed and dispersed with foamable microcapsules in some cases. Is impregnated with 5 to 40% by weight of the raw material for papermaking, and then heated and dried in a dryer cylinder to expand the expandable microcapsules, thereby producing a paper web having low density and characteristics in accordance with the design quality. I figured out a way. The wet impregnation method is a method of impregnating a formed paper web before drying by dipping it in an impregnation liquid. An example of a wet impregnation method is disclosed in US Pat.
As proposed in US Pat. No. 469, there is a method in which a wet paper web is held on a wire and immersed in an impregnating liquid and squeezed while preventing breakage of a paper layer (called a Novak method).

In the wet impregnation method, the paper web is subjected to press impregnation after being dewatered, and then enters the impregnation step without being dried. In addition, in the impregnation process, since the bonding between the pulp fibers has not yet occurred, the voids between the pulp fibers are much easier to expand when immersed in the impregnation liquid as compared with the dry impregnation processing method. A material having a large particle size, such as foamable microcapsules, can easily penetrate into the paper layer.

The pulp for papermaking used in the present invention is not particularly limited, and any pulp used in ordinary papermaking can be used. For example, softwood unbleached kraft pulp (NUKP), softwood bleached kraft pulp (NBKP),
The main material is wood pulp such as hardwood unbleached kraft pulp (LUKP), hardwood bleached kraft pulp (LBKP), softwood bleached sulphite pulp (NBSP), thermomechanical pulp (TMP), and groundwood pulp (GP). Non-wood pulp such as hemp, cotton, bamboo, straw pulp, kenaf, synthetic pulp made from polyethylene, polypropylene, polyacrylonitrile, etc., modified pulp such as cationized pulp, mercerized pulp, microfibrillated cellulose, etc. Can be used together. In addition to the above pulp, acrylic fiber, rayon fiber, polyester fiber, organic synthetic fiber such as polyamide fiber and glass fiber,
Various fibers such as carbon fibers, alumina fibers, silica / alumina silicate fibers, and inorganic fibers such as rock wool can be used alone or in combination as a mixture.

The foamable microcapsules used in the present invention are obtained by encapsulating a low-boiling solvent in resin fine particles.
3-5 times in diameter at relatively low temperature of ~ 150 ° C, 3 by volume
The particles having an average particle size of 5 to 30 μm which expand 0 to 120 times. As the resin, a thermoplastic resin composed of a copolymer such as vinylidene chloride, acrylonitrile, acrylic acid ester, and methacrylic acid ester is generally used.As the low boiling point solvent, usually isobutane, pentane, petroleum ether, hexane, and low boiling halogenated solvent are used. Use low-boiling solvents such as hydrocarbons. As a method for producing the expandable microcapsules, any conventionally known methods can be used.

When the foamable microcapsules are heated above the softening point of the resin forming the outer shell, the resin begins to soften,
At the same time, the encapsulated low-boiling solvent evaporates and the vapor pressure increases, with the result that the resin is expanded and expanded to form closed cells. Thereby, excellent heat insulating properties and cushioning properties can be obtained. These effervescent microcapsules include “Matsumoto Microsphere F-30”, “F-30GS” and “F-2” manufactured by Matsumoto Yushi Seiyaku Co., Ltd.
No. 0, F-50 and Expancel WU, DU sold by Japan Philite Co., Ltd., but the foamable microcapsules used in the present invention are not limited to these. Not something.

The amount of the foamable microcapsules is 2 to 20% by weight, preferably 4 to 15% by weight, based on the raw material for papermaking. If it is less than 2% by weight, a sufficiently low density cannot be obtained,
If the content exceeds 20% by weight, the effect will level off and it cannot be said that it is appropriate from the economical point of view. Further, the unevenness of the paper surface due to the expansion of the expandable microcapsules becomes extremely large, so that the thickness and the density are controlled. Becomes difficult.

The humidity control agent used in the present invention includes silica gel, silica alumina gel, alumina gel, activated alumina, synthetic zeolite, natural zeolite, synthetic silica, acid clay, activated clay, α-sepiolite, β-sepiolite, and palygorskite. (Attabalgite), allophane, imogolite, and other natural and synthetic inorganic powders having moisture absorption / release properties can be used alone or in combination of several types, and the amount used is 10 to 70% by weight.
If it is less than 10% by weight, the amount of moisture absorbed and released becomes small, and it is difficult to obtain a sufficient humidity control effect. If the content exceeds 70% by weight, the sheet strength is undesirably reduced.

The binder used in the internal addition or wet impregnation method in the present invention includes rubber latex such as natural rubber latex, styrene / butadiene copolymer latex, methyl methacrylate / butadiene copolymer latex and / or polyacrylate emulsion. , A synthetic resin emulsion such as a polyvinyl acetate emulsion, a polyvinyl chloride emulsion, an ethylene vinyl acetate emulsion, an ethylene acrylic emulsion, an ethylene vinyl chloride emulsion, an acrylic vinyl chloride emulsion, and an ethylene emulsion can be used alone or in combination of several kinds. . The amount of these binders used is 0 to 20 parts by weight, preferably 3 to 20 parts by weight, based on 100 parts by weight of the mixture of the papermaking pulp, the humectant and the expandable microcapsules. When low-density paper strength is not required, a binder may not be used,
Usually, when the amount is less than 3 parts by weight, the strength is weak, and powder dropping and the like are likely to occur. On the other hand, if the amount exceeds 20 parts by weight, the pores of the humidity control agent are covered by the binder, so that it is difficult to obtain a sufficient humidity control effect.

In the present invention, a known fixing / coagulant is used to fix the humidity control agent and the foamable microcapsules to the papermaking fiber. Examples of the fixing / coagulant include polyacrylamides, sodium polyacrylate, modified polyacrylamides, acrylamide / sodium acrylate copolymers, polymer coagulants such as polyethylene glycols, and aluminum salts such as aluminum sulfate and aluminum chloride. One or more known fixing and coagulants such as ferric salts such as ferric chloride, ferric sulfate and ferric nitrate, polyethyleneimine and polyepichlorohydrin can be used as appropriate. 0.02 to 5 parts by weight per minute is desirable.

Further, in the present invention, in addition to the above-mentioned main constituent materials of the humidity-controlling low density paper, a sizing agent, a paper strength enhancer, a dye,
Use known papermaking materials such as pigments, retention aids, various fillers, pH adjusters, slime control agents, stickers, preservatives, fungicides, flame retardants, etc. singly or in combination as necessary. be able to.

A typical production method of the present invention will be described by taking a wet impregnation method as an example. After adding a fixing agent to the paper stock in which the pulp for papermaking, the humectant and the foamable microcapsules are mixed and dispersed, the paper is formed by a known paper machine such as a long net, a circular net, and a short net to form a paper web. Moisture content is 50-6 by press part etc.
After dehydration to 0% by weight, put a paper web on a wire and
The foamed microcapsules are immersed in a 5% diluted synthetic resin emulsion impregnating solution, then squeezed, passed through a dryer cylinder, and dried while heating and foaming the foamable microcapsules. A humidity-controlling low-density paper having many foamed closed cells is obtained.

[0029]

EXAMPLES The present invention will be described below with reference to examples.
The grammage (g / m ² ) means a completely dried one. Example 1 40 parts by weight of softwood bleached sulphite pulp (NBSP) (in terms of dry weight, the same applies hereinafter) and 20 parts by weight of hardwood bleached kraft pulp (LBKP) were added to a moisture-absorbing and desorbing powder (trade name "Silica Gel PA-200B" Fuji) 40 parts by weight of Silysia Chemical Co., Ltd.) and 7 parts by weight of effervescent microcapsules (trade name “Matsumoto Microsphere F-30D” manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) are added, mixed and dispersed with a pulper, and then the paper stock is added. Sizing agent (trade name "Polymaron 360")
0.6 parts by weight of Arakawa Chemical Industry Co., Ltd.) and 1.5 parts by weight of a sulfuric acid band are added, and the paper is made with a fourdrinier paper machine according to a conventional method, and the paper is heated and foamed with a multi-cylinder cylinder drier and dried. Thereafter, a humidity-controlling low-density paper having a basis weight of 320 g / m ² was obtained.

Example 2 40 parts by weight of silica gel PA-200B and 7 parts by weight of Matsumoto Microsphere F-30D were added to 40 parts by weight of softwood bleached sulphite pulp (NBSP) and 20 parts by weight of hardwood bleached kraft pulp (LBKP). , A acrylate latex (trade name “Ni
pol LX811 (manufactured by Nippon Zeon Co., Ltd.) (10 parts by weight) and uniformly stirred and dispersed. 2 parts by weight of a sulfuric acid band and a polymer flocculant (trade name “High Holder 35”)
1) manufactured by Kurita Kogyo Co., Ltd.) and then papermaking was performed in the same manner as in Example 1, and the basis weight after drying was 3
15 g / m ² of a humidity-controlling low-density paper were obtained.

Example 3 A stock was prepared in the same manner as in Example 1, and the basis weight of the paper before impregnation was 290 g / m ^{2 by a} fourdrinier paper machine having a wet impregnating apparatus.
Paper and then diluted to 10% by weight
pol LX811 was immersed in an impregnating liquid to perform wet impregnation, and the squeezing conditions were adjusted so that the pickup rate became 10% by weight. Thereafter, the foam was heated and foamed in the same manner as in Example 1 to obtain a humidity-controlling low-density paper having a basis weight after drying of 319 g / m ² .

Example 4 40 parts by weight of silica gel PA-200B and 4 parts by weight of Matsumoto Microsphere F-30D were added to 40 parts by weight of softwood bleached sulphite pulp (NBSP) and 20 parts by weight of hardwood bleached kraft pulp (LBKP). And mixed and dispersed with a pulper. After adding 1.5 parts by weight of a sulfuric acid band and 0.06 parts by weight of a high holder 351 to this stock, the paper was made to have a basis weight of 280 g / m ² before impregnation in the same manner as in Example 3. And then wet-impregnated by immersion in an impregnating liquid dispersed and prepared so that Nipol LX811 is 10% by weight and Matsumoto Microsphere F-30D is 3% by weight.
The squeezing condition was adjusted so that the pickup rate became 13% by weight. Thereafter, the foam was heated and foamed in the same manner as in Example 1 to obtain a humidity-controlling low-density paper having a basis weight after drying of 316 g / m ² .

Comparative Example 1 65 parts by weight of softwood bleached sulphite pulp (NBSP) and 35 parts by weight of hardwood bleached kraft pulp (LBKP) were mixed and dispersed with a pulper, and then 0.6 parts by weight of Polymeron 360 and 0.6 parts by weight of sulfuric acid were added to the stock. 1.5 parts by weight of the band was added, the paper was made with a fourdrinier paper machine according to a conventional method, and the basis weight after drying was 320 g /
to obtain a paper m ^2.

Comparative Example 2 To 65 parts by weight of softwood bleached sulphite pulp (NBSP) and 35 parts by weight of hardwood bleached kraft pulp (LBKP), 7 parts by weight of Matsumoto Microsphere F-30D were added, mixed and dispersed with a pulper, and then mixed with Nipol. LX811 is 1
0 parts by weight were added and uniformly stirred and dispersed. After adding 2 parts by weight of a sulfuric acid band and 0.05 parts by weight of a high holder 351 to this stock, papermaking was carried out using a fourdrinier paper machine according to a conventional method.
Heated and foamed in the same manner as described above, and the basis weight after drying is 318 g.
/ M ² of low density paper.

Comparative Example 3 40 parts by weight of silica gel PA-200B were added to 40 parts by weight of softwood bleached sulphite pulp (NBSP) and 20 parts by weight of hardwood bleached kraft pulp (LBKP) and mixed and dispersed with a pulper. 1.5 parts by weight of a sulfuric acid band and 0.05 parts by weight of a high holder 351 were added to the stock, and then dried by heating with a multi-cylinder cylinder drier to obtain a basis weight of 320 g.
/ M ² was obtained.

Table 1 shows various physical properties of the low-density paper obtained for the above-described Examples and Comparative Examples. FIG.
Fig. 2 shows the change in humidity in the sealed container when the external environment was changed. Here, a is the inside of the sealed container enclosing the humidity control paper of Example 3, b is the inside of the closed container enclosing the humidity control paper of Comparative Example 3, c is the external environment, and d is no enclosing the humidity control paper. 3 shows a change in humidity in a blank closed container.

[0037]

[Table 1]

The evaluation was performed by the method described below. (1) Basis weight: JIS P-8124 (2) Thickness: JIS P-8118 (3) Tensile strength: JIS P-8113 (4) Air permeability: JIS P-8117 (5) Moisture absorption (%) :( measured weight - absolute dry weight) ÷ measurement weight × 100 (6) humidity performance: in variable air-conditioned room set up closed container 1 m ³ created in the aluminum plate, each low density paper 2Kg therein It was carried out by encapsulation. Variable air-conditioning room is 22 ° C, 5
The container was kept at 5% RH, the lid of the sealed container was opened, and after exposing for 4 hours with low-density paper, the container was sealed. Next, when the temperature in the variable air-conditioning room is alternately changed from 10 ° C. to 40 ° C. to 10 ° C. to 40 ° C. every six hours, the humidity change in the closed container is measured.
The obtained data was evaluated on a 5-point scale. 5: Excellent in humidity adjustment ability with respect to temperature change, quick response speed and little change in humidity. 4: Has the ability to adjust humidity to changes in temperature, has a fast response speed, and has little change in humidity. 3: There is a humidity adjustment ability with respect to temperature change, but the response speed is slow, and a drift is observed in humidity change. 2: Although the humidity adjustment ability with respect to the temperature change is somewhat high, the response speed is slow, and the humidity change tends to follow the temperature change. 1: Lack of humidity adjustment ability, humidity change follows temperature change.

From Table 1, it can be seen that in Examples 1 to 4, materials excellent in humidity control performance were obtained as compared with Comparative Examples. In other words, by introducing the humectant into the low-density paper, the structure is easily brought into contact with air, and a humidifying low-density paper having a quick response which has not been obtained in the past can be obtained. In the comparative example, a material having low density and humidity control performance as in the example was not obtained.

[0040]

As described above, the humidity-controlling low-density paper of the present invention has the following effects. Therefore, when storing or transporting an article requiring proper moisture maintenance, it can be used as a packaging material or underlay. And the like, and can effectively suppress deterioration and breakage of the article. (1) Excellent humidity control performance. (2) Cellulose fiber and inorganic powder are the main components,
It is an environmentally friendly material. (3) Due to the foaming effect of the foamable microcapsules, it is lighter, has a lower density, and has cushioning properties as compared with the same type of material. (4) Since hydrogen bonding between fibers is inhibited by highly filling the inorganic powder, the expandable microcapsules are more likely to expand in the process of heating and foaming, and as a result, the paper contains high powder. Nevertheless, low density can be achieved. (5) Since it has a low density, it has excellent moisture permeability and air permeability, and the effect of the humidity control agent can be efficiently obtained.

[Brief description of the drawings]

Table 1 is a table showing various physical properties of low-density papers obtained in Examples and Comparative Examples.

FIG. 1 is a diagram showing a change in relative humidity in a closed container when the temperature of an external environment is changed.

FIG. 2 shows 0 to 2 in FIG. 1 for easy understanding of the humidity control effect.
It is the figure which expanded time.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-243196 (JP, A) JP-A-54-14001 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) D21H 11/00-27/42

Claims (4)

(57) [Claims] 1. A papermaking fiber of 10 to 88 parts by weight and a hygroscopic powder of 10 to 7 parts by weight per 100 parts by weight of a moisture-controlling low-density paper.
0 to 20 parts by weight of a binder, 2 to 20 parts by weight of foamed microcapsules, and a density of 0.1 to 0.4 g / cm ^3. Density paper. 2. 10 to 88 parts by weight of papermaking fiber, 10 to 70 parts by weight of moisture-absorbing and releasing powder, 2 to 2 foamable microcapsules.
A paper stock is formed by papermaking with 0 parts by weight and, if necessary, a binder containing 0 to 20 parts by weight of a binder, and then the foamed microcapsules are foamed by heating the paper stock. A method for producing a humidity-controlling low-density paper. 3. 10 to 88 parts by weight of papermaking fiber, 10 to 70 parts by weight of a moisture-absorbing and releasing powder, 2 to 2 foamable microcapsules.
A basis weight before drying of 40 to 1000 g of a water content of 50 to 60% by weight formed by papermaking a paper material containing 0 parts by weight.
/ M ² (absolute dry basis weight) paper impregnated with a binder by 5-40% by weight with respect to the papermaking raw material by a wet impregnation method,
Subsequently, the foaming microcapsules are foamed by heating the paper web, thereby producing a humidity-controlling low-density paper. 4. A papermaking material containing 10 to 88 parts by weight of papermaking fiber and 10 to 70 parts by weight of a hygroscopic powder having a water content of 50 to 60% by weight. -10
A paper web of 00 g / m ² (absolute dry basis weight) is mainly impregnated with foamable microcapsules and a binder by 5 to 40% by weight based on a papermaking raw material by a wet impregnation method, and then the paper web is heated. A method for producing a humidity-controlling low-density paper, characterized in that foamable microcapsules are foamed with the method.