JP2000265391A - Readily breakable moisture-proof paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain readily breakable moisture-proof paper that is-readily breakable after use without containing water-repellent material, for example, wax by forming the moistureproof layer comprising a synthetic resin including a specific phyllosilicate salt on at least one face of the paper carrier. SOLUTION: One hundred parts by weight of a phyllosilicate salt, for example, white mica or phlogopite or the like, having an average particle size of 5-50 μm, an aspect ratio of >=5 and a shape factor of >=0.75 on the average are formulated to 0.1-5 pts.wt. of a silane-coupling agent and a synthetic resin, for example, styrene-butadiene copolymer latex at a weight ratio of 30/70-70/30 on the solid basis. Further, 100 pts.wt. of the above synthetic resin are combined with 0.01-10 pts.wt. of an active hydrogen-bearing compound, for example, polyamide-polyurea resin or the like to give the objective coating solution. The objective readily breakable moisture-proof paper is obtained by coating a paper carrier, for example, unbleached kraft paper of a basis weight of 50-350 g/m2 with the coating solution in an amount of 10-40 g/m2 each surface on the solid basis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moisture-proof wrapping paper which can be obtained without laminating a polyolefin or the like, and further does not contain a water-repellent material such as a wax so that it can be easily disintegrated even after use. The present invention relates to an easily disintegrating moisture-proof paper that can be recycled as used paper.

[0002]

2. Description of the Related Art Conventionally, for packaging of industrial and industrial products,
In order to prevent moisture and water absorption of the contents, polyolefin laminated paper (hereinafter referred to as poly-laminate paper) is used, in which a polyolefin polymer compound such as polyethylene or polypropylene, which is excellent in moisture resistance and water resistance, is laminated on a paper support. Was. Polyamide paper is used for packaging paper products, flat paper packaging such as art paper and coated paper, packaging for small-size paper stacks such as electrophotographic copying paper and inkjet paper, and heavy bags such as cement and resin. It is used for such purposes. However, polylami paper has poor disintegration properties due to its strong coating layer.Therefore, when it is recovered as waste paper and used as a raw material for pulp, the coating itself remains in a large sheet during disintegration, and the finely divided coating is used in the papermaking process. If mixed in, there will be various problems such as fusing to a cylinder dryer or the like. For this reason, polylami paper cannot be used as waste paper, and is currently incinerated after use.

On the other hand, as a method for producing an easily disintegrating paper having moisture resistance, for example, Japanese Patent Publication No. 55-22597,
JP-A-59-66598 is known. These are obtained by applying an aqueous emulsion obtained by blending a wax emulsion with a synthetic rubber latex on the paper surface. Such easily disintegrating moisture-proof paper has sufficient moisture-proof and waterproof properties and can be disaggregated as used paper, but the wax in the moisture-proof layer precipitates (bleed) on the surface of the moisture-proof layer and is transferred to the opposite back side of the moisture-proof paper. There is a problem that it becomes slippery and the wax is transferred to the contents and contaminates the contents. Also,
There is also a problem that paper manufactured using such moisture-proof paper containing wax as a raw material becomes slippery due to the wax.

[0004] The present inventors have studied the above problems, and as a result, have found that a moisture-proof paper having a moisture-proof layer containing no wax, that is, a moisture-proof layer is formed on at least one surface of a paper support. A layer having (a) a moisture-proof / film-forming synthetic resin, (b) tabular phyllosilicate compound particles having an average particle diameter of 5 to 50 μm and an aspect ratio of 5 or more;
(C) A moisture-proof paper containing a moisture-proof property improving agent was previously proposed (JP-A-9-291499).

According to the present invention, an excellent moisture-proof paper can be obtained by using a tabular phyllosilicate compound having a suitable average particle size in a moisture-proof layer. Further, such a moisture-proof paper is more excellent in the moisture-proof property as the flat phyllosilicate compound having a higher aspect ratio is used. Therefore, in order to improve the moisture-proof property or to reduce the coating amount of the moisture-proof paint, a moisture-proof layer using a tabular phyllosilicate compound having an optimized average particle diameter and a higher aspect ratio is desirable. However, in order to make the moisture-proof layer easy to disintegrate, the moisture-proof layer is formed by applying a water emulsion such as a synthetic resin latex and forming the film with the emulsion dried only to the extent that the emulsified particle shape remains. It is desirable to form by a polymer film. However, in the case of wrapping paper using a moisture-proof paper having such a moisture-proof layer, the moisture-proof layer is kept in a flat state in which the moisture-proof layer is not greatly deformed. When the moisture-proof layer is destroyed at a portion, a problem occurs in that the moisture-proof property of the portion is reduced. In particular, a decrease in moisture resistance due to the occurrence of pinholes that occur in the case of a packaging form having a vertex like a cross fold,
There has been a demand for a method of improving the moisture-proof property of the ruled line portion at the time of forming a ruled line when used as a liner of a moisture-proof cardboard.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an easily disintegrating moisture-proof paper in which the moisture-proof performance of the moisture-proof packaging paper when used in a packaging form having a fold is improved.

[0007]

The first aspect of the present invention is to provide a moisture-proof paper having a moisture-proof layer comprising a phyllosilicate compound and a synthetic resin on at least one surface of a paper support, wherein the phyllosilicate compound has an average shape factor. This is an easily disintegrating moisture-proof paper which is a mica group mineral having a value of 0.75 or more. The second aspect of the present invention is an easily disintegrating moisture-proof paper according to the preceding item, wherein the mica group mineral is treated with a coupling agent. In addition, the third of the present invention,
The easily disintegrating moisture-proof paper according to any one of the preceding items, wherein the synthetic resin is a styrene-butadiene copolymer. A fourth aspect of the present invention is the easily disintegrating moisture-proof paper according to any one of the preceding items, wherein the moisture-proof layer contains an active hydrogen-reactive compound.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have conducted intensive studies on the relationship between improvement in moisture resistance and phyllosilicate compounds which are pigments of moisture-proof paints. As a result, mica having a specific shape factor as phyllosilicate compounds has been found. The present inventors have found that the use of a group III mineral significantly improves the moisture-proof property of the folded portion, leading to the present invention. The present invention will be described in detail as follows. The phyllosilicate compound used in the present invention is a mica group mineral. Those belonging to the phyllosilicate compounds are generally plate-like or flaky and have distinct cleavages, and are composed of mica, pyrophyllite, talc, chlorite, septe chlorite, serpentine, stilp-nome. Lane, clay minerals,
Above all, mica group minerals are superior to other pigments in that they have a high aspect ratio, which is an index of tabularity, and that an optimum average particle size can be selected. Mica group minerals include muscovite (muscovite), sericite (sericite), biotite (flokopite), biotite (biotite), fluorophlogopite (artificial mica), red mica, soda mica, vanadin mica, and illite. , Chimica, paragonite, brittle mica and the like. Among such mica group minerals,
Muscovite and biotite have particle size, aspect ratio,
In view of the above, it is suitably used in the present invention.

In the present invention, these mica group minerals can be used arbitrarily, but a more preferable range of the average particle size (measured value by a laser diffraction method) is 1 μm to 100 μm.
μm, and more preferably 5 μm to 50 μm. When the average particle diameter is less than 1 μm, the orientation of the tabular pigment in the coating layer is hardly averaged with respect to the support, and 100 μm or less.
If the thickness exceeds m, a part of the tabular pigment protrudes from the coating layer, and as the thickness of the tabular pigment becomes about several μm, the number of layers of the oriented tabular pigment in the coating layer decreases. In any case, the effect of improving the moisture-proof performance is reduced. Further, in the relationship between the moisture-proof coating layer and the average particle size, it is desirable that the average particle size is not less than １ ／ of the thickness of the moisture-proof layer. If the thickness of the moisture-proof layer is less than 1/2, the orientation of the tabular pigment in the coating layer is unlikely to be parallel to the support.

The preferred aspect ratio of the mica group mineral (value obtained by dividing the average particle diameter by the thickness; the thickness is measured by observation with an electron microscope) is 5 or more, more preferably 10 or more. When the aspect ratio is 5 or less, the film cannot be oriented in parallel with the support in the moisture-proof layer, so that the moisture-proof property is poor. Also, the higher the aspect ratio, the greater the number of layers in the coating layer of the tabular pigment, so that high moisture-proof performance is exhibited.

The shape factor (ρ) in the present invention is obtained by the following equation. ρ = 4π × S / L2 That is, the shape factor (ρ) is a value obtained by multiplying the area (S) obtained by a projection from a photograph of a mica group mineral by 4π by the circumference (also obtained from the projection). L) squared. By the way, this value is 0.7 for a circle and 0.7 for a square.
85 and 0.605 for a triangle. Further, the shape coefficient of the mica group mineral having irregularities in the periphery has a small value even if it is substantially circular. The method for obtaining the shape factor will be described in more detail. First, a photograph of mica is taken with a scanning electron microscope to make a projection view. Approximately 100 mica pieces having a major diameter corresponding to the average particle diameter are taken out of the projections, and about 100 projections are taken out, magnified by an electronic copier, traced with a planimeter along the image, and the circumference of one mica and its Measure the area of the part surrounded by the circumference. The shape coefficient is calculated from the area and the circumference of about 100 individual mica pieces obtained by such a method, and a frequency curve of the shape coefficient is drawn. This cumulative number is 50%
The point at which the line is reached is taken as the average value. In the moisture-proof paper of the present invention, a moisture-proof layer using a mica group mineral having an average particle diameter of 5 to 50 μm, an aspect ratio of 5 or more, and a shape factor of 0.75 or more, more preferably 0.80 or more in average value. It has. The shape factor of the 100 mica pieces was 0.7.
The number of mica pieces of 0 or less is preferably 20 or less, and more preferably 10 or less.

Normally, mica is pulverized by a pulverization method giving strong impact energy like a jet mill type pulverizer, but the mica obtained by such a method is very irregular and has a shape factor. Only about 0.65 to 0.73 can be obtained. However, the mica preferably used in the present invention can be obtained by crushing with low impact energy and smoothing sharp corners. For example, a mica group mineral having a shape factor of 0.75 or more, which can be applied to the present invention, can be obtained by using a fine-micron type pulverizer, or by further pulverizing the pulverized product by ultrasonic wet grinding. In addition, since the energy at the time of pulverization is small, fine mica having a size of 5 μm or less is less likely to be generated, and fine irregularities remaining on the surface when one mica piece is taken out are reduced. Of course, these grinding methods are not limited to those described above. By using a mica-group mineral having such a shape factor for the moisture-proof layer, the anisotropy in the arrangement of mica in the moisture-proof layer is reduced, and it becomes uniform in both the X and Y directions. Extreme cracks are less likely to occur even when creased.

When the surface of the mica group mineral is observed with an electron microscope, fine exfoliated particles and fine powder adhering to the surface are confirmed.
When such a mica pigment is blended in the moisture-proof layer, the fine powder contained in the moisture-proof layer does not become parallel to the paper support in the coating layer, so that it is considered that a water flow path is formed in the moisture-proof layer. Further, the strips or the like attached to the surface of the plate-like particles hinder the adhesion between the synthetic resin and the mica group mineral and easily cause the formation of interfacial voids, which are also considered to be water channels. Therefore, it is considered that these fine powders and the like cause a decrease in moisture resistance. However, since the mica group mineral crushed to maintain the shape factor as described above is crushed with weak impact energy, such exfoliated fragments and fine powder hardly occur, and the surface is extremely flat. It has been confirmed that Therefore, by using a mica group mineral pulverized so as to have a shape factor of 0.75 or more as the pigment of the moisture-proof paint, it is considered that the folding moisture-proof property of the moisture-proof paper is greatly improved.

The synthetic resin used in the present invention is preferably used as an aqueous latex or an aqueous emulsion, for example, a styrene-butadiene copolymer, an acryl-styrene copolymer, a methacrylate-butadiene copolymer, An acrylonitrile-butadiene-based copolymer, an acrylic-based copolymer, a polyester-based copolymer, and a polyurethane-based copolymer are exemplified. Among these,
A styrene-butadiene copolymer having good water resistance, good elongation, and less likely to cause cracks in the coating layer due to breakage is preferred. Styrene-butadiene copolymer (SBR) is styrene, α-methylstyrene, vinyltoluene, pt
Aromatic vinyl compounds such as -butylstyrene and chlorostyrene and conjugated diene compounds such as butadiene, 1,3-butadiene, isoprene, 2,3 dimethyl-1,3-butadiene and 1,3-pentadiene, and copolymerizable with these This is a copolymer latex obtained by emulsion polymerization of a monomer composed of any other compound. Styrene is preferred as the aromatic vinyl compound, and 1,3-butadiene is preferred as the conjugated diene compound.

Other copolymerizable compounds include unsaturated carboxylic acids such as acrylic acid, methacrylic acid and crotonic acid; unsaturated polycarboxylic acids such as fumaric acid, maleic acid, itaconic acid and butenetricarboxylic acid; Partially esterified products of ethylenically unsaturated polycarboxylic acids such as monoethyl acrylate and monomethyl itaconate; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-amyl (meth) acrylate ,
Isoamyl (meth) acrylate, n (meth) acrylate
-Hexyl, 2-ethylhexyl (meth) acrylate,
(Meth) acrylates such as n-octyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate; cyano group-containing ethylenically unsaturated compounds such as (meth) acrylonitrile; glycidyl (meth) acrylate; Glycidyl ether of an ethylenically unsaturated acid of the formula:
Glycidyl ethers of unsaturated alcohols such as allyl glycidyl ether; (meth) acrylamide-based compounds such as (meth) acrylamide, N-methylol (meth) acrylamide, and N-butoxymethyl (meth) acrylamide are used. One or more of the above compounds can be used. Among these, unsaturated carboxylic acids having an active hydrogen, unsaturated polycarboxylic acids, and (meth) acrylamide compounds are preferred.

Although the composition ratio of each component of the monomer can be appropriately selected, usually, the aromatic vinyl compound 25 to 7 is used.
5 parts by weight, preferably 30 to 70 parts by weight, 20 to 60 parts by weight of the conjugated diene compound, preferably 25 to 50 parts by weight,
0 to 50 parts by weight of other copolymerizable compounds. The glass transition temperature (Tg) of the synthetic resin in the present invention is -1.
0 ° C to 40 ° C, more preferably -5 ° C to 35 ° C.
If the Tg is lower than -10 ° C, the disintegration becomes poor and blocking tends to occur. On the other hand, if the Tg exceeds 40 ° C., the moisture resistance deteriorates. In addition, the blending ratio (solid content weight) of the phyllosilicate compound and the styrene-butadiene-based latex used in the present invention is 30:70 to 70:30, preferably 35:65 to 60:40. In order to form a moisture-proof layer having disaggregation using these synthetic resins, the resin to be used is a copolymer film formed from a water emulsion such as a synthetic resin latex, and the shape of the emulsified particles remains. It is desirable to keep it dry.

In the present invention, when a coupling agent is used in the moisture-proof layer, the moisture-proof property is further improved. Examples of the coupling agent to be used include a silane coupling agent containing Si in a hydrophilic portion, a titanate coupling agent containing Ti in a hydrophilic portion, and an aluminum coupling agent containing Al in a hydrophilic portion. The structure of the coupling agent is roughly divided into a hydrophilic group that interacts with an inorganic compound such as a phyllosilicate compound, and a hydrophobic group that interacts with an organic compound such as a resin. And the like, and are obtained by hydrolyzing an alkoxy group bonded to a metal element such as Si or Si.

On the other hand, as for the hydrophobic group of the coupling agent, when the hydrophobic group is an organic oligomer, an organic polymer film is formed on the surface of the inorganic compound, and the surface is completely hydrophobized to adhere to the resin matrix. It has the effect of enhancing the nature. Further, when the hydrophobic group has a reactive organic functional group such as an epoxy group, a vinyl group, and an amino group, the functional group and the reactive functional group of the resin matrix are cross-linked, and the adhesiveness with the resin matrix is further increased. . The coupling agent includes γ-glycidoxypropyltrimethoxysilane, γ
-(2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, methyltriethoxysilane, γmercaptopropyltrimethoxysilane, vinylacetoxy Examples include silane, γ-chloropropyltrimethoxysilane, γ-anilinopropyltrimethoxysilane, and isopropyltri (N-aminoethylaminoethyl) titanate.

In the present invention, it is more desirable that the phyllosilicate compound is subjected to a surface treatment by an integral blend method or a pretreatment method using such a coupling agent before use. The integral blending method is a method in which a coupling agent is directly added to a coating solution containing a phyllosilicate compound and a synthetic resin. The pretreatment method is a method in which the surface of a phyllosilicate compound is treated in advance with a coupling agent. The addition amount of the coupling agent is 0.1 to 5 parts by weight, preferably 0.5 to 2 parts by weight based on 100 parts by weight of the phyllosilicate compound. If the amount is less than 0.1 part by weight, the surface of the phyllosilicate compound is not sufficiently coated with the coupling agent, which is not preferable. If the amount exceeds 5 parts by weight, the effect of the coupling agent will level off. Economy.

In the present invention, the moisture-proof property can be improved by adding an active hydrogen-reactive compound to the moisture-proof layer. The active hydrogen reactive compound used in the present invention reacts with an active hydrogen functional group such as a carboxyl group, an amide group or a hydroxyl group contained in the synthetic resin to crosslink the synthetic resin latex to polymerize (three-dimensional network structure). Things. Such active hydrogen-reactive compounds (1) those having a methylol group and causing a dehydration condensation reaction with the hydrophilic functional group (melamine-
(2) a compound having an aldehyde group and causing an addition reaction with the hydrophilic functional group (such as glyoxal); (3)
Those having an epoxy group and causing a ring-opening addition reaction with the hydrophilic functional group (eg, polyglycidyl ether); (4) having a polyvalent metal and forming a coordination bond and a covalent bond with the hydrophilic functional group (5) cationic compounds such as polyamine compounds and polyamide resins such as polyamidoamine resins and polyamide epichlororesins, which are cationic in aqueous solution and form ionic bonds with anionic functional groups. The amount of the active hydrogen-reactive compound is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the synthetic resin latex. When the amount of the active hydrogen-reactive compound is less than 0.01 part by weight,
It is not preferable because the reactivity between the active hydrogen reactive compound and the active hydrogen functional group is remarkably reduced. If the content exceeds 10 parts by weight, the effect on the improvement of moisture permeability and the anti-blocking property is leveled off, or the unreacted active hydrogen reactivity is reduced. It is not preferable because a problem such as precipitation of a compound occurs.

A moisture-proof paint (water-based) by mixing the above materials
But if necessary, a dispersant such as polycarboxylic acid,
An antifoaming agent, a surfactant and a color adjusting agent can be further added. This paint is applied to a paper support by a conventional method to form a moisture-proof layer. The coating equipment is not particularly limited,
A coating method such as a blade coater, a bar coater, or an air knife coater that scrapes the coating surface is preferable because it tends to promote the orientation of the tabular pigment. When coated on one side (when coated on both sides, the coated amount of both sides), the coating amount of moisture resistance and amount is 10 to 40 g / m ² as a solid content,
More preferably, it is 15 to 30 g / m ² .

The paper support used in the present invention is not particularly limited as long as it is mainly composed of pulp which is easily dispersed in water by mechanical disaggregation. Unbleached kraft paper (acid paper or neutral paper) is preferred. Although there is no particular limitation on the basis weight of the paper support, it is usually 50 to 350 g / m ² .

The moisture permeability of the moisture-proof paper of the present invention is determined by the desired moisture-proof performance.

Hereinafter, the present invention will be described specifically with reference to Examples. Unless otherwise specified, “parts” and “%” represent “parts by weight” and “% by weight”, respectively.

[0025]

<Example 1> Phlogopite is pulverized with a fine micron type pulverizer (manufactured by Hosokawa Micron Co., Ltd.), and fine powder is divided by an air classifier and coarse components are cut off with a sieve to obtain an average particle diameter of 4 μm.
Phlogopite having 0 μm, an aspect ratio of 40 and an average shape factor of 0.80 was obtained. Among them, those having a shape factor of 0.70 or less were 7 out of 100 pieces. The shape factor of the mica was obtained by enlarging a photograph taken with a scanning electron microscope and obtaining the area and the perimeter using a planimeter. Styrene butadiene latex (Tg 20 ° C, gel fraction 9
(4%, solid content: 50%), 100 parts by weight, stirred, and further, 50 parts by weight of the pulverized and classified phlogopite powder were added thereto with stirring, and the moisture-proof paint was bleached to kraft paper (basis weight: 70%).
g / m ² , thickness 100 μm) was coated on one side with a solid content of 25 g / m ² , and dried at 110 ° C. for 1 minute using a hot air drier to produce a moisture-proof paper.

<Example 2> The phlogopite was pulverized by the pulverizer used in Example 1, and further classified to cut a fine powder portion by 5% and a coarse portion by 30% to obtain an average particle diameter of 20 μm and an aspect ratio. 30, phlogopite having an average shape factor of 0.78 was obtained. Among them, those having a shape factor of 0.70 or less were 11 out of 100 pieces. To 50 parts by weight of water, 2 parts by weight of 25% aqueous ammonia and 0.5 part by weight of an aminosilane coupling agent (KBM603: manufactured by Shin-Etsu Chemical Co., Ltd., active ingredient: 99% or more) were added and stirred, and then styrene butadiene latex was added. (Tg 20 ° C., gel fraction 94%, solid content 50%)
0 parts by weight and 50 parts by weight of mica powder were added sequentially with stirring to prepare a moisture-proof coating, and a moisture-proof paper was produced in the same manner as in Example 1.

<Example 3> The muscovite was crushed by the crusher used in Example 1, and the fine powder portion was cut by air classification to obtain an average particle diameter of 45 µm, an aspect ratio of 45, and an average shape factor of 0.4. A moisture-proof paper was manufactured in the same manner as in Example 1 except that 81 mica was used. The number of the muscovite having a shape factor of 0.70 or less was 15 out of 100.

<Examples 4 and 5> A moisture-proof paper was produced in the same manner as in Example 2 except that the following coupling agent was used. Example 4: Epoxysilane coupling agent (trade name: K
Example 5: Amino titanate coupling agent (trade name: BM403, manufactured by Shin-Etsu Chemical Co., Ltd.)
(KR44, manufactured by Ajinomoto Co., Inc.)

Example 6 50 parts by weight of water, 2 parts by weight of 25% aqueous ammonia, an aminosilane coupling agent (KB)
(M603: Shin-Etsu Chemical Co., Ltd., active ingredient: 99% or more) 0.5 part by weight was added and stirred, and then a polyamide polyurea resin (SR302: Sumitomo Chemical Co., Ltd., solid content 60) was used as an active hydrogen-reactive compound. %), 100 parts by weight of styrene butadiene latex (Tg 20 ° C., gel fraction 94%, solid content 50%), and 50 parts by weight of mica having an average particle diameter of 40 μm treated in the same manner as in Example 1. The moisture-proof paint prepared by adding while stirring was applied to bleached kraft paper (basis weight 70 g / m ² , thickness 100 μm) as a solid content on one side 23.
g / m ^{2 was applied and} dried at 110 ° C. for 1 minute using a hot air drier to produce a moisture-proof paper.

Comparative Example 1 An average particle diameter of 38 μm and an aspect ratio of 28 obtained by pulverization using a jet mill were used.
A moisture-proof paper was manufactured in the same manner as in Example 1 except that phlogopite having an average shape factor of 0.70 was used. Of the 100 mica, 50 had a shape factor of 0.70 or less. <Comparative Example 2> obtained by pulverization using a roller mill,
Average particle diameter 20 μm, aspect ratio 31, shape factor 0.
A moisture-proof paper was manufactured in the same manner as in Example 2 except that 68 mica was used. Shape factor 0.70 out of 100 mica
The following were 55 items. <Comparative Example 3> obtained by pulverization using a jet mill,
A moisture-proof paper was manufactured in the same manner as in Example 3, except that muscovite having an average particle diameter of 43 μm, an aspect ratio of 47, and a shape factor of 0.65 on average was used. Of the 100 mica, 60 had a shape factor of 0.70 or less.

<Test Method> 1) Moisture-proof paper cut out in a circular shape, cut in half, and further cut in half.
Samples obtained by creased so as to be evenly divided into JIS
According to the Z0208 B method (cup method), the moisture permeability was measured at 40 ° C. and 90% (relative humidity) with the coated surface facing outward.

Table 1 shows the measurement results of the above Examples and Comparative Examples.

[0033]

[Table 1]

From Table 1, it is clear that when the mica group mineral having an average shape factor of 0.75 or more is used (Examples 1 and 2), the fold moisture resistance is remarkably improved. (Refer to Comparative Examples 1 and 2.) When the mica group mineral having a large shape factor and a coupling agent are used together (Examples 2 and 4 to 5), it is clear that better moisture-proof properties are obtained. It is. Further, by adding the active hydrogen reactive compound, the moisture proof property is further improved. (Example 6)

[0035]

According to the present invention, it is possible to provide an easily disintegrating moisture-proof paper having improved moisture-proof performance when having a fold.

[Brief description of the drawings]

FIG. 1 is a view obtained by enlarging an electron micrograph of phlogopite of Example 1 and tracing the outline thereof. FIG. 2 is an enlarged electron micrograph of the phlogopite of Comparative Example 1 and similarly traced.

Claims (4)

[Claims] 1. A moisture-proof paper having a moisture-proof layer comprising a phyllosilicate compound and a synthetic resin on at least one side of a paper support, wherein the phyllosilicate compound is a mica-group mineral having an average shape factor of 0.75 or more. An easily disintegrating moisture-proof paper characterized by the following. 2. The easily disintegrating moisture-proof paper according to claim 1, wherein the mica group mineral is treated with a coupling agent. 3. The easily disintegrating moisture-proof paper according to claim 1, wherein the synthetic resin is a styrene-butadiene copolymer. 4. The easily disintegrating moisture-proof paper according to claim 1, wherein the moisture-proof layer contains an active hydrogen reactive compound.