JP2903024B2 - Moisture proof paper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moisture-proof paper and, more particularly, to a water-disintegratable moisture-proof paper having excellent moisture permeability (ie, waterproofness) at a fold.

[0002]

2. Description of the Related Art Conventionally, for packaging of plain paper such as high quality paper,
Moisture-proof paper (hereinafter also referred to as laminated moisture-proof paper) is used in which a polyolefin such as polyethylene or polypropylene is laminated on a paper material with a thickness of about 15 micrometers to improve moisture permeability. When wrapping plain paper such as high-quality paper with moisture-proof paper, so-called caramel packaging in which the moisture-proof paper is folded to wrap the plain paper is performed. Although this moisture-proof paper is excellent in moisture-permeability, it does not substantially disintegrate in water even when it is tried to be recycled because it contains polyolefin, and is currently not reused.
In addition, when discarded, polyolefins do not decompose in the natural environment, so they remain in the environment and cause environmental destruction.

[0003] In recent years, wax emulsions, resin emulsions,
Moisture proof paper in which a water disintegrating desiccant such as latex or a mixture thereof is applied to a paper material has been used (for example, JP-A-53-41511, JP-A-56-14).
8997, JP-A-61-47896, JP-A-3-279492, etc.). Since this moisture-proof paper uses a water-disintegrating moisture-proofing agent, it can be easily disintegrated in water and easily regenerated.

[0004] In a moisture-proof paper coated with a water-disintegrating moisture-proofing agent,
The moisture permeability in a planar state (hereinafter, usually referred to as moisture permeability) is sufficient to be comparable to that of laminated moisture-proof paper, and some of them have reached a level that is practically acceptable. However, when the moisture-proof paper is folded and used as described above, plastic deformation of the polymer material, which is the solid content of the water-disintegrating moisture-proofing agent, occurs at the fold, and the molecular chain is cut in a microscopic manner and the macroscopically. Causes breakage and peeling, and the moisture permeability of the fold (hereinafter referred to as the fold moisture permeability) increases. When the moisture permeability of the fold increases, moisture invades from the fold and the high quality paper or the like to be packaged absorbs moisture. Double feed, in which two sheets of paper in contact with each other are sent at one time, is likely to occur. In particular, the end of the high quality paper near the fold has a large amount of moisture absorption. When feeding paper to the copier, the paper feed roller and separation pad of the copier first contact the edge of the high-quality paper,
If this end absorbs moisture, there is a problem that the probability of occurrence of double feeding becomes extremely high.

[0005]

It is conceivable to apply a large amount of a water-disintegrating desiccant in order to increase the moisture-permeability of the moisture-proof paper. Although water vapor transmission can be suppressed normally by applying a large amount of water disintegrating desiccant, the flexibility of the film decreases due to the increase in the film thickness, and rupture or peeling at the fold tends to occur. It will be raised.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a moisture-proof paper having low water vapor permeability while maintaining good water disintegration.

[0007]

SUMMARY OF THE INVENTION The present inventors have pointed out that in order to prevent double feeding in a copying machine or the like, it is important to lower the fold moisture permeability even if the moisture permeability is usually sacrificed to some extent. Attention has been paid, and as a result of intensive studies, the present invention has been completed. That is, the present invention made to achieve the above-mentioned object is a water-disintegratable moisture-proof paper obtained by applying a water-disintegratable moisture-proofing agent on a paper material, and has a water vapor permeability of 80 or more.
g / m ² · 24h or less and the following formula

[0008]

(Equation 2)

The moisture-proof paper is characterized in that the rate of decrease in moisture permeability obtained therefrom is not more than 50% (claim 1).

According to the present invention, the moisture permeability is usually 80 g / m
And ² · 24h or less, and since the moisture permeability decrease ratio is 50% or less, for example, moisture absorption is suppressed in the packaged product of quality paper or the like, effectively prevents double feeding when feeding a high quality paper in copier it can. In the present invention, the rate of decrease in moisture permeability is 50%.
In order to achieve the following, the polymer material, which is the solid content of the water-disintegrating desiccant, can follow the paper material when the moisture-proof paper is folded. Thereby, the molecular chains are prevented from being cut, broken, and peeled from the paper material. Specifically, (1) To use a polymer material having extremely excellent flexibility, or (2) To reduce the coating amount of the water disintegrating desiccant to reduce the thickness of the film and increase the flexibility of the entire film. And the like.

In particular, when the means (2) is used, the weight of the moisture-proof paper can be reduced, the production cost can be reduced, and the water-disintegrating moisture-proofing agent is mixed in the paper component after the water-disintegration. This is preferable because the ratio can be reduced to improve the quality of the recycled paper. By reducing the coating amount of the water disintegrating desiccant and reducing the film thickness, the moisture permeability usually rises to some extent, but as described above, the fold moisture permeability decreases in order to prevent double feeding in copying machines. It is urgent and usually has a moisture permeability of 8
If it is maintained at 0 g / m ² · 24 h or less, there is no practical problem. From this viewpoint, the coating amount is 5 g / m in terms of solid content.
^It is preferably from ^{2 to} 30 g / m ² (claim 2).

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of a moisture-proof paper 1 according to one embodiment of the present invention. The moisture-proof paper 1 has a coating 2 formed of a solid content of the water-disintegrating moisture-proofing agent by applying a water-disintegrating moisture-proofing agent onto the paper material 3.

As the paper material 3, for example, high-quality paper, medium-quality paper, bleached kraft paper, unbleached kraft paper, single-glazed unbleached kraft paper, liner paper, and paper tube base paper can be used. The weighing of the paper material 3 is not particularly limited.
It is appropriately selected and used from those of 0 g / m ² or more and 300 g / m ² according to the purpose of use.

As the water disintegrating desiccant used for the film 2, a conventionally used wax emulsion, resin emulsion, latex, a mixture thereof and the like are used. In order to suppress the breakage moisture permeability, it is preferable to use a water-disintegrating desiccant in which a flexible polymer material is dispersed.

[0016] When water is used defibration properties desiccant, the coating amount 5 g / m ² or more 30 g / m ² or less is preferable in terms of solid content. When the coating amount is less than the above range, the moisture permeability is usually increased, which may cause a practical problem. Conversely, if the coating amount exceeds the above range, the rate of decrease in moisture permeability will increase, and the high-quality paper or the like to be packaged may easily absorb moisture.
To sufficiently suppress the increase in the rate of decrease in moisture permeability, the coating amount is 25 g.
/ M ² or less, more preferably 20 g / m ² or less, from the viewpoint of reducing the weight of the moisture-proof paper, reducing the production cost and improving the quality of the recycled paper.

As a method of applying the water disintegrating desiccant to the paper material 3, various known methods can be adopted, and for example, it may be applied by a bar coater, a roll coater, a blade coater, a kiss coater or the like. The application of the water disintegrating desiccant may be performed not only on one side of the paper material 3 as shown in FIG. 1 but also on both sides.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.

A water-disintegrating desiccant was applied to unbleached kraft paper weighing 75 g per square meter at a coating amount shown in Table 1 below and dried. A moisture-proof paper was obtained. A commercially available moisture-proof paper coated with a styrene-butadiene copolymer-based water disintegration desiccant was used as the moisture-proof paper of Comparative Example 2. The obtained commercially available moisture-proof paper was used as the moisture-proof paper of Comparative Example 3,
A commercially available moisture-proof paper coated with an acrylic resin-based water disintegrating moisture-proofing agent was used as the moisture-proof paper of Comparative Example 4. The amount of the water disintegrating desiccant applied to this commercially available moisture-proof paper is not known in detail.
The moisture-proof paper of each of these Examples and Comparative Examples was subjected to the following evaluation.

[Water disintegration test] The moisture-proof paper was broken to an appropriate size, about 24 g was prepared in an absolutely dry amount and charged into a stirrer.
The mixture was stirred for 5 minutes under the condition of rpm. This was hand-made with a hand-making machine, and the product of water disaggregation was visually determined. In all the moisture-proof papers of Examples and Comparative Examples, water disaggregation was good.

[Moisture permeability test] B of JIS-Z-0208
Based on the method, the moisture permeability was measured with the film outside. The moisture permeability when using moisture-proof paper without fold was defined as normal moisture permeability, and the moisture permeability when using moisture-proof paper with fold was defined as fold moisture permeability. The fold is JIS-Z-1514
It was provided by bending the moisture-proof paper according to the method for testing the cold resistance in the inside. From the normal moisture permeability and the fold moisture permeability, the rate of decrease in moisture permeability was determined based on the above formula. Tables 1 and 2 below show normal moisture permeability, fold moisture permeability, and reduction rate of moisture permeability. FIG. 2 shows the relationship between the normal water vapor transmission rate and the fold water vapor transmission rate of the moisture-proof paper except for Comparative Examples 2, 3 and 4 which are commercially available products.

[Measurement of the number of times of double feeding] A4 size fine paper (trade name "My Paper" manufactured by NBS Ricoh Co., Ltd.)
After preparing 20,000 sheets each and drying them sufficiently in a constant temperature and humidity chamber, 500 sheets were wrapped with the moisture-proof paper (48 cm × 55 cm) of each Example and each Comparative Example.
The end was glued. Five of these were put into a cardboard case, and eight cardboard cases were prepared.
Put this in a constant temperature and humidity chamber at 40 degrees Celsius and 80% relative humidity.
After holding for 0 hours, the printer speed becomes 100 sheets /
min copying machine (9790KP manufactured by Fuji Xerox Co., Ltd.)
S) was used for a continuous paper passing test. A total of 20,000 high-quality papers were passed through each of the moisture-proof papers, and the number of times double feeding occurred was measured using a counter of a copying machine. The measurement results are shown in Tables 1 and 2 below.

[0023]

[Table 1]

[0024]

[Table 2]

From Table 1 and FIG. 2, it can be seen that the moisture permeability decreases with an increase in the coating amount, and that the breakage moisture permeability decreases to a certain extent with an increase in the coating amount. It turns out that it rises conversely. This is because the coating thickness increases with an increase in the coating amount, the flexibility of the coating is impaired, plastic deformation of the polymer material occurs at the fold, molecular chain breakage, breakage or separation from the paper material occurs Because it is. As a result, as shown in Table 1,
As the amount of application increases, the rate of decrease in moisture permeability increases.

Further, from Tables 1 and 2, the moisture-proof paper of each of the examples in which the rate of decrease in moisture permeability is 50% or less is shown in Comparative Examples 1, 2 and 3 in which the rate of decrease in moisture permeability is 50% or more. It can be seen that the number of double feeds is smaller than that of the moisture-proof paper of No. 3. This indicates that the rate of decrease in moisture permeability must be 50% or less in order to prevent double feeding. In addition, the moisture-proof paper of Comparative Example 4 has a moisture permeability reduction rate of approximately 45%, which is almost in a favorable range, but since the moisture permeability is usually high, the number of times of double feeding is extremely large. From this, the normal moisture permeability is 80 g
/ M ² · 24h or less. When the water disintegrating desiccant applied to the moisture-proof paper of each of these Examples and Comparative Example 1 is used, the rate of decrease in moisture permeability is 5 by controlling the applied amount to 30 g / m ² or less in terms of solid content.
0% or less, in particular, the coating amount is 25% in terms of solid content.
It can be seen that the rate of decrease in moisture permeability can be extremely reduced by setting it to g / m ² or less.

As described above, in the present moisture-proof paper, the moisture permeability is normally reduced to 50% or less and the normal moisture permeability is set to 80 g / m ² · 24h.
In other words, since both the imperviousness of the folded part and the imperviousness of the part other than the fold are compatible, it prevents moisture absorption of the high-quality paper to be packaged and suppresses double feeding. be able to.

The moisture-proof paper of the present invention has been described above by taking the case of packing high-quality paper as an example. However, the present moisture-proof paper having a small reduction rate of moisture permeability is not limited to the packaging of high-quality paper. Packaging, steel coil packaging, steel plate packaging,
It is used with a crease, such as packaging for papermaking and a material for moisture-proof corrugated cardboard, and can be applied to all applications that require moisture-proof and waterproof properties. In addition, the present moisture-proof paper is used in a curved state, such as a moisture-proof paper tube, so that it can be applied to applications in which a resin coating layer is subjected to stress. Furthermore, this moisture-proof paper does not actively break such as packaging foodstuffs, cement, seasonings, etc., but may break or wrinkle during transportation and storage. It can also be applied to applications that may roll up.

[0029]

As described above, according to the present invention,
It is possible to provide a moisture-proof paper that can suppress moisture permeability from a fold portion and a portion other than the fold while maintaining good water disintegration properties, and can prevent moisture absorption of a packaged object.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a moisture-proof paper according to an embodiment of the present invention.

FIG. 2 is a graph showing the results of a moisture permeability test.

[Explanation of symbols]

 1. Moisture proof paper 2. Film 3. Paper material

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁶ , DB name) D21H 11/00-27/42

Claims (2)

(57) [Claims] 1. A water-disintegratable moisture-proof paper obtained by applying a water-disintegratable moisture-proofing agent on a paper material, which usually has a moisture permeability of 80 g / m ² · 24 h or less and the following formula: ] A moisture-proof paper characterized in that the rate of decrease in moisture permeability obtained in (1) is 50% or less. 2. The moisture-proof paper according to claim 1, wherein the applied amount of the water-disintegrating desiccant is 5 g / m ² or more and 30 g / m ² or less in terms of solid content.