JP3531314B2 - 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 having moisture-proof and slip-proof properties and capable of being re-disintegrated.

[0002]

2. Description of the Related Art Conventionally, for the winding of high-quality paper, bleached kraft paper, unbleached kraft paper, various coated papers, and packaging of high-quality papers and coated plain papers, it is necessary to prevent the product from absorbing moisture. In order to
A wrapping paper laminated with a polyolefin-based polymer compound such as polyethylene or polypropylene to impart moisture resistance and water resistance is used. Also, cement bags, salt bags,
Heavy-duty base paper such as feed bags, fertilizer bags, and garbage bags are required to have two performances: moisture resistance and strength to withstand their weight, in order to prevent moisture absorption and water absorption of the contents after bag making and bagging. Currently, bags are made by stacking kraft paper with polyolefin-laminated paper (hereinafter referred to as poly-laminated paper) in which kraft paper is laminated with polyethylene, polypropylene, etc. However, these poly-laminated papers cannot be reused as waste papers because they do not disintegrate in water, and there is only a disposal method such as incineration or landfill, and there is concern about environmental pollution, and there are many problems.

On the other hand, as a moisture-proof wrapping paper that can be disintegrated and reused as waste paper, instead of the plastic film laminate, an aqueous emulsion obtained by adding rosin and higher alcohol to paraffin wax and petroleum resin is used on one side of kraft paper or A method for producing a moisture-proof paper by coating on both sides has been disclosed (JP-A-50-3.
6711). Also disclosed is a paper moisture-proofing composition comprising a mixture of a synthetic hydrocarbon resin and a styrene-maleic acid copolymer of wax and a surfactant, and a thermoplastic acrylic emulsion (Patent Document 1). 56-148997). Further disclosed is a method for producing a moisture-proof paper, which comprises applying a paraffin wax, an esterification product of a modified rosin and a polyhydric alcohol, liquid polybutene, and a wax emulsion mainly composed of rosin or a mixture with a synthetic rubber-based latex. (Japanese Patent Laid-Open No. 61-47896). In addition, for moisture-proof paper that can be reused as waste paper, the production of moisture-proof paper is based on applying a coating solution that mixes certain synthetic rubber latex and wax emulsion to the base paper. A method is disclosed (packaging technology, September 1982 issue, pages 42 to 46).

Moisture-proof paper having a moisture-proof layer containing such a wax component is a moisture-proof paper having re-disintegration property, and the layer formed by bleeding wax on the surface of the moisture-proof layer is moisture-proof and waterproof. It is said to exert its performance. However, if a large amount of wax component in the moisture-proof layer is blended for the purpose of improving the moisture-proof property of the moisture-proof paper, when the moisture-proof paper is wound into a roll, the wax on the surface of the moisture-proof layer is transferred to the opposite paper surface and It becomes slippery because the coefficient of friction of the paper surface is greatly reduced. In the most extreme case, if packaging is performed so that the transfer surfaces are in contact with each other, serious problems such as uneven loading of the packages and dropping during transportation occur.

In order to solve such a problem, a moisture-proof and waterproof paper having a slip-resistant layer made of an amphoteric compound on the opposite side of the moisture-proof layer is disclosed (Japanese Patent Publication No. Sho 56-1871).
2). When the slip-preventing layer is formed on the opposite surface of the moisture-proof layer in this way, slippage can be reduced, but when the winding roll is finished, the moisture-proof layer and the backside anti-slip layer come into contact with each other with a strong winding pressure, and the anti-slip layer pigment Causes minute scratches on the surface of the moisture-proof layer, and water vapor permeates through the scratched portions, so that the moisture-proof property of the moisture-proof layer is significantly deteriorated.

As described above, the moisture-proof layer containing the wax component is
The layer formed by the bleeding of the wax on the surface exhibits moisture-proof and waterproof properties, but on the other hand, it also causes a problem of slippage and does not satisfy the required quality. That is, the present situation is that no moisture-proof paper having re-disintegration property, moisture-proof property superior to that of plastic film, and causing no problem of slipping of a package has not yet been considered.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a moisture-proof paper having a moisture-proof layer containing wax as a constituent component, which has excellent moisture-proof performance and small slipperiness.

[0008]

[Means for Solving the Problems] The present inventors diligently studied the problem of slippage of moisture-proof paper containing wax. The slipperiness of the moisture-proof layer containing wax depends on the amount of wax contained in the moisture-proof layer. Therefore, after creating a moisture-proof layer in which the amount of wax in the moisture-proof layer consisting of wax and synthetic resin latex has been reduced to the utmost limit, the wax present on the surface of the moisture-proof layer is transferred to the back surface of the paper support and the sliding friction coefficient between the transfer surfaces. Was measured. It was found that the obtained results depend on the composition of the moisture-proof layer, but the coefficient of friction cannot be improved unless the wax content is 1% or less. However, even with a moisture-proof layer prepared by reducing the amount of wax thus blended, when the friction coefficient was measured again after several months, it was much less than the initial value and very slippery compared to when the moisture-proof layer was initially formed. I found out. It is considered that this is because the hydrophobic wax in the moisture-proof layer spontaneously bleeds to the surface because the air has hydrophobicity and is oriented to the surface of the moisture-proof layer.

It is considered that the bleeding wax forms a very thin layer on the very surface of the moisture-proof layer. For example, when measuring the contact angle of the moisture-proof layer surface with water,
The contact angle of the synthetic resin latex used alone was around 60 °, whereas the moisture-proof layer containing wax showed around 104 °, which was in agreement with the literature value of the surface contact angle of wax. In addition, in an environment of 40 degrees lower than the melting point of wax, 2
When the moisture-proof paper was left to stand for about 4 hours, the migration of wax in the moisture-proof layer was promoted, and the friction coefficient was lowered to the same level as natural time. A similar idea is disclosed in JP-A-53-41511. In this report, regarding the mechanism that the moisture-proof layer containing wax and synthetic resin exhibits moisture-proof property, "Wax migrates to the surface or the interface with the support. However, it forms an extremely thin hydrophobic thin layer to prevent water from entering. ”

In order to prevent the migration of the wax to the surface of the moisture-proof layer, the inventors of the present invention have further conducted extensive studies, and as a result, by mixing a specific pigment in the moisture-proof layer, the migration of the wax to the surface of the moisture-proof layer is prevented. It was clarified that the amount of wax bleeding over time to the surface of the moisture-proof layer can be reduced because of blocking in the middle of the layer Z direction. As a result, the amount of wax transferred to the back surface, which is the surface opposite to the moisture-proof layer, was reduced, and it was found that the friction coefficient can be kept high, and the present invention was accomplished.

That is, the moisture-proof paper of the present invention has the following constitution. 1. A moisture-proof paper having a moisture-proof layer containing a wax and a synthetic resin latex formed on at least one surface of a paper support, wherein the moisture-proof layer has an aspect ratio of 5 or more and a particle size of 5 to 5
Contains 0 micron tabular pigment and the wax is n
-A paraffin component is contained, the content of the n-paraffin component is 0.5 to 5.0% by weight based on the entire moisture-proof layer, and the compounding ratio of the tabular pigment and the synthetic resin latex is
Is a moisture-proof paper having a ratio of 10:90 to 70:30 . 2. 2. The moisture-proof paper according to 1, wherein the synthetic resin latex contains at least one of styrene butadiene latex, acrylic styrene latex, methacrylate butadiene latex and acrylonitrile butadiene latex. 3. 3. The moisture-proof paper according to 1 or 2, wherein the tabular pigment is a phyllosilicate mineral.

[0012]

In the present invention, the moisture-proof layer containing a wax is mixed with a tabular pigment having a specific shape to extend the water vapor permeation distance to improve the moisture-proof property and at the same time to extend the wax bleeding distance. , Reduce the amount of wax present on the surface of the coating layer. In addition, the wax is trapped in 20 to 50% of the closed cells generated in the coating layer as a secondary additive, and the amount of wax on the surface of the coating layer is further reduced.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The tabular pigment used in the present invention has an average particle size of several μm.
It is a substantially flat crystalline pigment having a particle size of m or more and an average particle diameter measured by a laser diffraction method is in the range of 1 to 200 μm. Among them, 3 to 100 μm is suitable, and more preferably 5 to 50 μm. Particularly, the particle size effective for preventing moisture and preventing wax migration is 10 to 40 μm. If the particle size is 5 μm or less, the effect is small because the orientation of the tabular pigment in the coating layer is less likely to be parallel to the support, and if it is 50 μm or more, a part of the tabular pigment is applied to the coating layer. It is presumed that the effect is lost because the thickness of the tabular pigment is about several μm and the number of oriented tabular pigments in the coating layer is reduced.

The aspect ratio is obtained by dividing the average particle diameter of the tabular pigment by the thickness, but it is necessary that the tabular pigment has an aspect ratio of 5 or more in order to exert the effects of the present invention. is there. Particularly preferred is an aspect ratio of 10
It is the above tabular pigment. Those having an aspect ratio of 5 or less cannot be oriented parallel to the coated surface, and the effect is not exhibited. The larger the aspect ratio, the greater the number of layers of the tabular pigment in the coating layer and the higher the effect.

The thickness of the tabular pigment for calculating the aspect ratio was measured by observation with an electron microscope. The thickness of the tabular pigment depends on the type of pigment, the pulverization method, and the average particle size. If the type of pigment and the crushing method are the same, the thickness increases as the average particle diameter of the pigment increases, and as a result, the magnitude of the aspect ratio hardly changes. Although the thickness can be reduced by pulverization, it is unavoidable that the particle size is simultaneously reduced by any pulverization method. For example, wet-milled muscovite having an average particle size of 40 μm has an average thickness of about 2 μm and an aspect ratio of 20.
Becomes In addition, the average particle size of muscovite mica that has been wet-milled is 20
The thickness of μm is about 1 μm and the aspect ratio is 20. Of course, even if the average particle size is 20 μm, it is 2 to 60.
It has a particle size distribution of about μm and a thickness of 0.1 to several μ.
Although it has a range of m, it becomes 1 μm on average.

When tabular pigments having these shapes are used in the moisture-proof layer of the present invention, if a pigment having an average particle size that is too small for the thickness of the coating layer is used, the pigment in the coating layer is used as a support. Since the number of those oriented in parallel with that is decreased, it is necessary to excessively increase the coating amount. Therefore, according to the studies made by the present inventors, it is preferable to use a tabular pigment having an average particle diameter of 20% or more based on the thickness of the coating layer. On the other hand, the tabular pigment having an average major axis of the coating layer thickness or more is not preferable because a part thereof may protrude from the coating layer during coating, or a void may be formed in the coating layer during bending, Even if it is used, it must be used in a small amount.

The tabular pigment used in the present invention includes a phyllosilicate mineral. Those belonging to the phyllosilicate minerals are plate-like or flaky and have clear cleavages, mica, pyrophyllite, talc (chlorite), chlorite, septe greenstone, serpentine, stilpnomelene, clay There are minerals. Among these, minerals that produce large amounts of particles when produced and have a large amount of production, for example, mica and talc are preferable. Mica includes muscovite (mascobite), sericite (serisite), phlogopite, biotite, fluorophlogopite (artificial mica), red mica, soda mica, vanadine mica, illite, Examples include chimica, paragonite, and brittle mica.

Clay minerals such as kaolin are also generally called tabular crystals. Certainly, if one crystal is taken, there is a flat plate portion, but it is granular as a whole. Of course, among the kaolin, among the deramie kaolin which is intentionally peeled off the crystal layer and cut into a flat plate, those having a particle size of 5 μm or more are included in the present invention.

Of these, the most preferred tabular pigments include muscovite, sericite and talc having a particle size, an aspect ratio,
It is preferable in terms of cost. To further describe these pigments, the composition of muscovite powder has the general formula: K2
It is expressed by O · 3Al2O3 · 6SiO2 · 2H2O. This muscovite rough stone is pulverized and classified by a dry method such as a hammer mill, and a portion having a desired particle size distribution is used, or wet pulverization such as a sand mill in which glass beads are used as a pulverizing medium in water is performed to obtain a desired particle size. Get the mica of the distribution. At this time, in order to maintain the aspect ratio, crushing without applying excessive force, or wet crushing while applying ultrasonic waves (U
By taking into consideration such as SP3240203), it is possible to obtain a mica powder having a high aspect ratio. Usually, the aspect ratio of the pigment obtained by these methods is 20 to 30 as observed by an electron microscope.
A part with an aspect ratio of about 100 can be obtained, but industrial production is difficult and the cost is high.

Sericite, which is called sericite as opposed to muscovite, has a similar chemical composition, and is composed of SiO2 / Al2.
The proportion of O3 is slightly large and the content of K2O is small. However, since sericite has finer gemstones than muscovite, the average particle size of sericite obtained by crushing and classification is generally 0.
It is about 5 to 2 μm, and most of the commercially available products are in this range. For this reason, in order to carry out the present invention, it is necessary to use sericite having a specifically large particle size distribution, which greatly eases the pulverization conditions, and the classification residual coarse particles of general-purpose products. Further classify from, and use the one with a particle size distribution that passes a mesh of the required size. By such a treatment, sericite having an aspect ratio substantially the same as that of muscovite can be obtained, and an aspect ratio of 10 to 30 is general.

Talc, which is also called roxeki, is a hydrate of magnesium silicate and is generally in the form of foil flakes. However, the particle size of talc that is generally commercially available is 0.1
It is about 3 μm, and in order to carry out the present invention, a coarse one for ceramics is used, or a particle size of about 10 μm can be obtained by performing the same crushing and classification operation as that of sericite. Further, the aspect ratio of talc is smaller than that of muscovite or sericite and is about 5 to 10.

As described above, muscovite has a larger size of rough stone than sericite and talc, and the particle size distribution can be freely selected by pulverizing and classifying. On the other hand, sericite is
The rough stone is small, but the cleavage is large, and the crushed product is flat like the muscovite, which is preferable. Although talc is not so large in particle size and aspect ratio, it can be used in a large amount because of its cost advantage.

The wax used in the moisture-proof paper consisting of wax and synthetic resin latex includes plant waxes such as candelilla wax, carnauba wax and rice wax, animal waxes such as beeswax, lanolin and its derivatives, and whale wax. , Mineral waxes such as montan wax and ceresin wax, paraffin wax and derivatives thereof, petroleum waxes such as microcrystalline wax and petrolactam wax, Fischer-Tropsch wax, polyethylene wax, montan wax and derivatives thereof, microcrystalline wax and derivatives thereof Examples thereof include hardened castor oil, liquid paraffin, and synthetic wax such as aliphatic amide such as stearic acid amide.

Among them, paraffin wax is preferable as the wax used in the moisture-proof layer of the present invention, and the normal type wax is particularly preferable. This is because the moisture-proof performance is higher than that of other plant-based, animal-based, petroleum, and synthetic waxes. Probably due to its straight-chain shape, the normal paraffin diffuses relatively easily and uniformly in the coating layer, and exhibits a high effect even when used in a small amount. The amount of iso- and cyclo-type paraffins originally present on the surface of the moisture-proof layer is higher than that of the normal type due to the difficulty of movement within the layer due to its branching and ring structure. It is not preferable because it increases.

In the present invention, the amount of wax added to the moisture-proof layer is required to be as small as possible and the amount of wax existing on the surface from the beginning of formation of the moisture-proof layer must be minimized. Paraffin is preferred.

Regarding the wax, it is necessary to consider the melting temperature distribution, not the melting point itself.
Also in the present invention, the wax moves to some extent in the moisture-proof layer with time, so that a part of the wax needs to be melted at around room temperature. In other words, in the research conducted by the present inventors,
When measured by DSC at 0 ° C / min, normal paraffin wax with a melting point of 74 ° C, which does not melt at 40 ° C at all, is inferior in moisture resistance, and conversely, normal paraffin wax that melts by 50% or more at around 40 ° C also has low moisture resistance. It was
Since the former has a melting point of 70 ° C or higher, it does not melt at 40 ° C, which is the moisture permeability measurement condition of the resulting moisture-proof paper, and the wax does not bleed, resulting in poor moisture resistance. The latter has a melting point of 40 ° C or higher. It is presumed that the effect is insufficient due to the severe melting and the large drop-off from the moisture barrier. That is, a normal paraffin wax containing a component that melts at a temperature slightly higher than room temperature, and a wax having a melting point of 50 to 70 ° C., which has a melting point distribution of 40 ° C. in part, may be used.

Of course, as in the conventional moisture-proof layer composed of wax and synthetic resin latex, maleinized or fumarized rosin and esterified product of polyhydric alcohol, polybutene, rosin, polyhydric alcohol, petroleum resin and the like are eutectic heated or mixed. An emulsion containing a wax that has been emulsified with an organic amine, ammonia, a surfactant, a styrene-maleic acid copolymer or the like after heating, or a substance that exhibits tackiness such as rosin or its ester derivative or polybutene as a component other than the wax An emulsion containing can be used.

The wax content is preferably 0.5 to 5% as a paraffin component. With the added amount of 5% or more,
The effect of adding the tabular pigment to be mixed cannot be fully exerted,
The friction coefficient on the back surface is likely to decrease. If it is 0.5% or less, the bleeding of the wax can be suppressed, but the distribution of the wax in the layer becomes non-uniform, so that the moisture-proof performance is poor and the expected performance cannot be obtained.

Examples of the synthetic resin latex used in the present invention include styrene butadiene latex (SBR), acrylic styrene latex, methacrylate butadiene latex, acrylonitrile butadiene latex and the like. SBR is preferable because it is unlikely to occur and has good water resistance. Here, the polymerizable monomer is mainly styrene and 1,3-butadiene, but other styrene and 1,3-
A monomer copolymerizable with butadiene can be used within a range that does not impair the object of the present invention. Other monomers copolymerizable with styrene and 1,3-butadiene include aromatic vinyl monomers such as α-methylstyrene, vinyltoluene, pt-butyltoluene and chlorostyrene;
Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-amyl (meth) acrylate, isoamyl (meth) acrylate, (meth)
N-Hexyl acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, (meth)
(Meth) acrylic acid ester monomers such as 2-hydroxyethyl acrylate and hydroxypropyl (meth) acrylate; cyano group-containing ethylenically unsaturated monomers such as (meth) acrylonitrile; glycidyl acrylate and methacrylic acid Glycidyl esters of ethylenically unsaturated acids such as glycidyl; glycidyl ethers of unsaturated alcohols such as allyl glycidyl ether; (meth) such as (meth) acrylamide, N-methylol (meth) acrylamide, N-butoxymethyl (meth) acrylamide Acrylamide-based monomers; and the like, and these polymerizable monomers can be used alone or in combination of two or more kinds. However, SB containing a copolymerization component (several% to several tens%) with methyl methacrylate, acrylonitrile, acrylic acid, acrylamide, etc. and many emulsifiers (several%).
Since all of these functional groups of R are more hydrophilic than styrene and butadiene, it is preferable that R is not included as a copolymerization component as much as possible.

The particle size of the synthetic resin latex is generally 100 nm to 300 nm, but the particle size is 150 nm.
In particular, a latex having a small particle diameter of about 60 to 90 nm is particularly preferable because the film-forming property is improved and a film with few defects can be formed. The glass transition temperature (Tg) of synthetic resin latex and the gel amount (the remaining amount of extraction with an organic solvent such as tetrahydrofuran and the polymer component having a molecular weight of 100,000) are the blocking of the coating layer (adhesion between the coating surface and the surface of the packaged object). ) Affects ease and film formability. A synthetic resin latex having a low Tg and a low gel amount facilitates blocking but improves film forming properties. High Tg, high gel content synthetic resin latex
Blocking becomes difficult, but film formability is reduced. Usually, the Tg is -30 to 50 ° C, preferably -15 to 30 ° C, the gel amount is in the range of 30 to 95%, preferably 60 to 90%, and the Tg and the gel amount are balanced in terms of film-forming property and blocking. To decide.

The mixing ratio of the pigment and the synthetic resin latex is 1
0:90 to 70:30, preferably 30:70 to 60:
It is appropriately determined within the range of 40. When the content of the pigment is less than 10%, the effect of adding the pigment cannot be sufficiently obtained, and the wax is liable to slip due to bleeding. Further, the film-forming performance of the synthetic resin latex is too high, and the disintegration property of the obtained moisture-proof paper is lowered, which causes inconvenience in collecting used paper. When the amount of the pigment is more than 70%, the voids between the pigment and the latex are increased, the closed cells are changed into the continuous cells, and the film-forming performance of the layer is significantly lowered, so that the expected moisture resistance cannot be obtained. In addition, the resistance against bending of the layer is lowered, which is not preferable.

The above-mentioned synthetic resin latex, tabular pigment and wax are mixed and, if necessary, diluted with water to a desired solid content concentration to prepare a coating solution. 10 to 30 g / m ^{2 of} the solid content of the coating solution is applied to the base paper as a support by a conventional method,
The coating amount is preferably 15 to 25 g / m ² . Coating amount is 10g /
If it is less than m ² , the coating rate of the paper surface of the paint is insufficient and pinholes and the like frequently occur, so that a sufficient moistureproof effect cannot be obtained. Further, even when the coating amount exceeds 30 g / m ² , the moisture resistance is slightly improved, which is economically unfavorable.

The coating can be carried out by a conventional method, and examples thereof include roll coating, bar coating, air knife coating, blade coating and gap coating. The coating liquid is applied to the base paper by such a method and then dried.

The support may be one that is easily dispersed in water by mechanical disaggregation, such as chemical pulp such as hardwood kraft pulp and softwood kraft pulp, and fine paper made from pulp selected from mechanical pulp, etc., Examples include medium quality paper, single-gloss kraft paper, Ryosara kraft paper, and kraft stretch paper. There is no particular limitation on the basis weight of these base papers, and those having a basis weight of 30 to 300 g / m ² are appropriately selected and used according to the purpose.

In the moisture-proof paper of the present invention, the amount of wax added is low, and since the tabular pigment that suppresses the bleeding is blended, slippage on the back surface is small. It also has the effect of improving the disintegration property of the coating layer by the breakage of the tabular pigment at the time of disaggregation, which is ideal for improving the slippage of moisture-proof paper containing a large amount of wax and the low disintegration property of polylaminated paper. It can be said that it is a moisture-proof paper.

The present invention will be specifically described below with reference to examples, but the following examples do not limit the present invention. All parts by weight in the examples are in solid content.

[0037]

【Example】

Example 1 Mica A21 which is a tabular pigment (muscovite, particle size 20 μm)
m, aspect ratio 20-30, manufactured by Yamaguchi Mica Industry Co., Ltd.) 10
0 parts by weight and 100 parts by weight of water were dispersed for 2 hours at a rotation speed of 2000 rpm using a Cowles disperser. 50 parts by weight of the obtained mica A21 dispersion and synthetic resin latex OX10
50 parts by weight of 60 (SBR latex, Tg 8 ° C., gel amount 70%, manufactured by Nippon Zeon Co., Ltd.) were mixed, and n-paraffin wax emulsion (melting point 67 ° C.) was used as a wax.
2 parts by weight of the moisture-proof coating obtained by hand-coating on unbleached kraft paper with a Mayer bar to a coating amount of 25 g / m2, and then using a hot air circulation dryer at 110 ° C. It was dried for 1 minute to prepare a moisture-proof paper.

Examples 2 to 7 Moisture-proof papers were prepared in the same manner as in Example 1 using the following tabular pigments. Example 2 Mica A11 (muscovite, particle size 5 μm, aspect ratio 20 to 30, manufactured by Yamaguchi Mica Industry Co., Ltd.). Example 3 Mica A31 (muscovite, particle size 33 μm, aspect ratio 20 to 30, 〃). Example 4 Mica A41 (muscovite, particle size 40 μm, aspect ratio 20 to 30, 〃). Example 5 Mica A61 (muscovite, particle size 50 μm, aspect ratio 20 to 30, 〃). Example 6 Shuwen (talc, particle size 15 μm, aspect ratio 20 to 30, manufactured by Chuo Kaolin Co., Ltd.) Example 7 Sericite ST (sericite, particle size 14 μm, aspect ratio 10 to 20, manufactured by Horie Kako Co., Ltd.) )

Example 8 Alon A was used as a synthetic resin latex.
Moisture-proof paper was prepared in the same manner as in Example 1 except that 104 (acrylic styrene, manufactured by Toagosei Co., Ltd.) was used.

Example 9 A synthetic resin latex was added to L-15.
A moisture-proof paper was prepared in the same manner as in Example 1 except that the composition was 37 (SBR, Tg 19 ° C., gel amount 70%, manufactured by Asahi Kasei Co., Ltd.).

Example 10 60 parts by weight of the flat material A21, synthetic resin latex O
A moisture-proof paper was prepared in the same manner as in Example 1 except that 4010 parts by weight of X1060 was used.

Example 11 30 parts by weight of tabular pigment A21, synthetic resin latex O
A moisture-proof paper was prepared in the same manner as in Example 1 except that X1060 was changed to 70 parts by weight.

Example 12 As a wax, 0.5 n-paraffin wax emulsion was used.
A moisture-proof paper was prepared in the same manner as in Example 1 except that the parts by weight were used.

Example 13 A moisture-proof paper was prepared in the same manner as in Example 1 except that 4 parts by weight of n-paraffin wax emulsion was used as the wax.

Comparative Example 1 A polyethylene-laminated paper obtained by laminating polyethylene on a non-bleached kraft paper with a thickness of 15 μm.

Comparative Example 2 65 parts by weight of synthetic resin latex OX1060 and 35 parts by weight of wax emulsion OKW-40 (mixed emulsion of paraffin wax, polybutene and rosin resin, manufactured by Arakawa Chemical Industry Co., Ltd.) were mixed. Moisture-proof paper was prepared by hand-coating the unbleached kraft paper with a Mayer bar so that the coating amount was 20 g / m 2.

Comparative Example 3 A moisture-proof paper was prepared in the same manner as in Example 1 except that PC talc (talc, particle size 2 μm, aspect ratio 2 to 4, manufactured by Daio Engineering) was used as the tabular pigment.

Comparative Example 4 Mica B72 (muscovite, particle size 82 μm) was used as a tabular pigment.
m, aspect ratio 20 to 30, manufactured by Yamaguchi Mica Industry Co., Ltd.), and moisture-proof paper was prepared in the same manner as in Example 1.

Comparative Example 5 A moisture-proof paper was prepared in the same manner as in Example 1 except that 7 parts by weight of n-paraffin wax emulsion was used as the wax.

Comparative Example 6 As a wax, 0.2 n-paraffin wax emulsion was used.
A moisture-proof paper was prepared in the same manner as in Example 1 except that the parts by weight were used.

Comparative Example 7 5 parts by weight of tabular pigment A21, synthetic resin latex OX
A moisture-proof paper was produced in the same manner as in Example 1 except that 1060 was used in 95 parts by weight.

Comparative Example 8 A moisture-proof paper was prepared in the same manner as in Example 1 except that a carnauba wax emulsion (vegetable wax emulsion, melting point 83 ° C.) was used as the wax.

Comparative Example 9 A moisture-proof paper was prepared in the same manner as in Example 1 except that beeswax (animal wax emulsion, melting point 60 to 67 ° C.) was used as the wax.

<Test Method> 1) Moisture Permeability Measured according to JIS Z0208 B method (cup method) with the coated surface facing outward. If it is 50g / m2 · 24h or less as a standard of moisture permeability, it is sufficiently practical. 2) Friction coefficient The moisture-proof surface was transferred to the back surface of the moisture-proof paper, and the friction coefficient between the back surfaces was measured by the method according to JIS P8147 to obtain the friction coefficient. However, the measurement speed was 150 mm / min. For the transfer of the wax on the moisture-proof surface and the back surface, the moisture-proof surface and the back surface were overlaid and the paper was passed once through a super calendar at a line pressure of 12 kg / cm. By this transfer, the coefficient of friction between the back surfaces when the moisture-proof paper is wound and manufactured is almost equal. When the moisture-proof paper is packaged with the back surface facing outside and is stacked and transported, a load collapse is likely to occur when the friction coefficient between the back surfaces is 0.4 or less. In particular, it is desirable to have a coefficient of friction of 0.5 or more in terms of safety when transporting heavy objects. 3) Disaggregation 8 g of moisture-proof paper, which had been cut into pieces of about 3 cm square, was stirred with 500 ml of water for 1 minute 30 seconds with a household mixer (the blade was scraped off with a file so as not to cut the fiber). Using the obtained slurry, a handmade sheet having a basis weight of 60 g / m ² was prepared with a laboratory handmade machine. The presence or absence of undisaggregated substances (film pieces, paper pieces) was visually evaluated, and those not containing undisaggregated substances were evaluated as ◯ and those containing undisaggregated substances were evaluated as x.

<Evaluation result>

[0056]

[Table 1]

From Table 1, the moisture-proof paper composed of the tabular pigment, synthetic resin latex and paraffin wax showed good results in terms of moisture permeability, friction coefficient and disintegration property. It is preferably within a range of ˜50 μm. On the other hand, it is understood that polyethylene laminated paper has poor disintegration property and moisture-proof paper containing a large amount of wax has a low friction coefficient.

[0058]

[Table 2]

Further, it can be seen from Table 2 that good moisture resistance and disintegration property can be exhibited by using styrene-butadiene latex, acrylic styrene latex, etc. having an appropriate Tg and gel amount as the synthetic resin latex.

[0060]

[Table 3]

It can be seen from Table 3 that when n-paraffin wax is added and the compounding ratio of the n-paraffin wax and the synthetic resin latex and the pigment is set to an appropriate amount, a moisture-proof paper having high moistureproof performance and slip resistance can be obtained.

[0062]

As shown in Tables 1 to 3, the particle size is 5 to 5
A moisture-proof paper composed of a 0 μm tabular pigment, a synthetic resin latex, and n-paraffin wax has excellent moisture-proofness and disaggregation, and has a high friction coefficient.

─────────────────────────────────────────────────── --Continued from the front page (56) Reference JP-A-55-30419 (JP, A) JP-A-7-133600 (JP, A) JP-A-9-291499 (JP, A) JP-A-9- 21096 (JP, A) JP-A-3-45675 (JP, A) JP-A-5-179600 (JP, A) JP-B-49-32771 (JP, B1) International Publication 94/028243 (WO, A1) (JP 58) Fields investigated (Int.Cl. ⁷ , DB name) D21H 11/00-27/42

Claims (3)

(57) [Claims] 1. A moisture-proof paper having a moisture-proof layer containing a wax and a synthetic resin latex formed on at least one surface of a paper support, wherein the moisture-proof layer is a flat plate having an aspect ratio of 5 or more and a particle diameter of 5 to 50 μm. Pigment-containing pigment, the wax contains an n-paraffin component, the content of the n-paraffin component is 0.5 to 5.0% by weight based on the entire moisture-proof layer, and the pigment and the synthetic resin latex Mixing ratio of
Is 10:90 to 70:30, and a moisture-proof paper. 2. The moisture-proof paper according to claim 1, wherein the synthetic resin latex contains at least one of styrene butadiene latex, acrylic styrene latex, methacrylate butadiene latex and acrylonitrile butadiene latex. 3. The moisture-proof paper according to claim 1, wherein the tabular pigment is a phyllosilicate mineral.