JP2001288694A - Moistureproof paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a moistureproof paper handleable similarly to polyethylene- laminated wrapping paper, high in moistureproofness, and easily collectible when turned into waste paper, and furthermore, substantially retaining its moistureproofness even after folded. SOLUTION: This moistureproof paper collectible when turned into waste paper is such that at least one side of a paper base as substrate is provided with a layer formed of (A) a polyvinyl alcohol-based polymer and (B) a swellable fluoromica-based mineral, preferably comprising the components A and B and substantially containing no wax, and having a moisture permeability of <=100 g/cm2.24 h.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to recoverable moisture-proof paper having a moisture-proof layer formed on a paper support. More particularly, the present invention relates to a moisture-proof paper which is easy to disintegrate when used for recycling.

[0002]

2. Description of the Related Art It is a known technique to apply or bond a polymer compound which can be melt-molded on a paper support to prevent the permeation of water vapor. However, this type of paper has a moisture barrier function because the coating layer is strong,
When recovering waste paper, there are problems such as pulp fibers remaining in a floc shape and the coating itself remaining in a large sheet shape.Therefore, there is no choice but to incinerate it.There are problems in terms of environmental protection and resource reuse. is there.

For example, polyethylene, polypropylene,
Alternatively, products coated, bonded and internally added on a support using a polymer compound such as polyvinylidene chloride have sufficient moisture-proof properties. Will be significantly inhibited.

On the other hand, a method for producing a moisture-proof paper by applying an emulsion containing a paraffin wax having a specific composition to one or both sides of kraft paper as wrapping paper from which waste paper can be recovered (Japanese Patent Laid-Open No. 50-37111). ), A mixture of a synthetic hydrocarbon resin and a wax with an emulsion obtained by dispersing the resin in water using a styrene-maleic acid copolymer and a surfactant, and a moisture-proofing composition for paper (Japanese Unexamined Patent Publication No. Sho 56). No. 148997). Further, a paraffin wax having a specific melting point, an esterified product of maleated or fumarated rosin and a polyhydric alcohol, liquid polybutene, and a wax emulsion containing rosin as a main component, or the wax emulsion and a synthetic rubber-based latex Is applied to the surface of a fibrous base material such as high quality paper or kraft paper, and dried under heating (Japanese Patent Application Laid-Open No. 61-47896).

[0005] All of these are moisture-proof papers having re-disintegration properties. However, moisture-proof papers containing these waxes may have a moisture-proof property depending on the extremely thin water-repellent layer formed by the wax. There is a tendency that the moisture-proof property of the bent portion is extremely reduced. In addition, the disintegration conditions had to be strict.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to overcome the basic disadvantages of these moisture-proof papers containing wax,
It is an object of the present invention to provide a moisture-proof paper which can be handled in the same manner as polyethylene-laminated wrapping paper, has excellent moisture-proof properties, and can easily collect used paper.

[0007]

An object of the present invention is to provide a moisture-proof paper having a paper substrate as a support, wherein at least one surface of the paper substrate has a polyvinyl alcohol-based polymer (A) and a swellable fluoromica-based material. Having a layer formed from mineral (B),
This is achieved by providing a moisture-proof paper having a moisture permeability of 100 g / m2 · 24 hr or less.

Another object of the present invention is to provide a moisture-proof paper having a paper substrate as a support, wherein at least one surface of the paper substrate has a polyvinyl alcohol polymer (A) and a swellable fluoromica mineral (B). Having a layer substantially free of wax, and having a moisture permeability of 100 g
/ M2 · 24 hr or less.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The polyvinyl alcohol polymer (A) used in the present invention is obtained by saponifying a saponified vinyl ester polymer or a copolymer of another vinyl monomer copolymerizable with the vinyl ester. can get. In carrying out the polymerization, known methods such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method can be employed. Above all, a bulk polymerization method or a solution polymerization method in which polymerization is carried out without a solvent or in a solvent such as an alcohol is usually employed, and when a polymer having a high degree of polymerization is obtained, an emulsion polymerization method is employed. Examples of the alcohol used as a solvent during the solution polymerization include lower alcohols such as methyl alcohol, ethyl alcohol, and propyl alcohol.
As the initiator used for the polymerization, for example, α, α′-azobisisobutyronitrile, 2,2′-azobis (2,4
-Dimethylvaleronitrile), 2,2'-azobis (4-
Known initiators such as azo initiators such as methoxy-2,4-dimethylvaleronitrile), benzoyl peroxide, and n-propylperoxycarbonate, and peroxide initiators are exemplified. The polymerization temperature is not particularly limited, but is in the range of -30 to 150 ° C.

Examples of the vinyl ester monomer (A) used in the above-mentioned method include vinyl formate, vinyl acetate, vinyl propionate, vinyl pivalate, and the like. In general, vinyl acetate is used.

In the present invention, as the polyvinyl alcohol-based polymer (A), a modified PVA containing an α-olefin unit having 4 or less carbon atoms is advantageously used in terms of moisture resistance. A method for producing a modified PVA containing an α-olefin unit having 4 or less carbon atoms is obtained by saponifying a copolymer of a vinyl ester and an α-olefin having 4 or less carbon atoms. The α-olefin having 4 or less carbon atoms includes, for example, ethylene, propylene, n-butene, isobutene, and the like.However, ethylene is preferred from the viewpoint of obtaining a moisture-proof paper having both the moisture-proof property and the waste paper collecting property of the present invention. Is preferred. The content of the α-olefin unit having 4 or less carbon atoms is preferably from 1 to 20 mol%, more preferably from 2 to 15 mol%, from the viewpoints of moisture proofness and recovered paper recovery. If the amount of the α-olefin is more than 20% by mole, the recovery of waste paper tends to decrease, which may cause difficulty in the process.

In the polyvinyl alcohol used in the present invention, an ethylenically unsaturated monomer copolymerizable with a vinyl ester may be copolymerized as long as the effects of the present invention are not impaired. Examples of the ethylenically unsaturated monomers include unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, fumaric acid, (anhydride) maleic acid, and itaconic acid or salts thereof, and mono- or dialkyl esters having 1 to 18 carbon atoms. Acrylamide, N-alkylacrylamide having 1 to 18 carbon atoms, N, N-dimethylacrylamide, 2
-Acrylamidopropanesulfonic acid or a salt thereof,
Acrylamides such as acrylamidopropyldimethylamine or an acid salt thereof or a quaternary salt thereof; methacrylamide, N-alkylmethacrylamide having 1 to 18 carbon atoms, N, N-dimethylmethacrylamide, 2-methacrylamidopropanesulfonic acid or the like; Methacrylamides such as salts, methacrylamidopropyldimethylamine or an acid salt or a quaternary salt thereof; N-vinylamides such as N-vinylpyrrolidone, N-vinylformamide and N-vinylacetamide; acrylonitrile, methacrylonitrile and the like. Vinyl cyanides; vinyl ethers having 1 to 18 carbon atoms such as alkyl vinyl ethers, hydroxyalkyl vinyl ethers and alkoxyalkyl vinyl ethers; vinyl chloride, vinylidene chloride, vinyl fluoride , Vinylidene fluoride, vinyl halides such as vinyl bromide; allyl acetate, allyl chloride, allyl alcohol, dimethylallyl alcohol, trimethyl- - (3-acrylamido-3-dimethylpropyl) -
Examples thereof include ammonium chloride, acrylamide-2-methylpropanesulfonate, and an α-olefin having 1 to 20 carbon atoms and containing a hydroxyalkyl group. The content of these units is preferably 20 mol% or less.

The viscosity average degree of polymerization of the polyvinyl alcohol used in the present invention (hereinafter abbreviated as polymerization degree) is not particularly limited, but the polymerization degree is usually 50 to 10,000.
Preferably 100-8000, more preferably 100-
It is selected from the range of 4000. For example, when used as a moisture-proof layer of moisture-proof paper, PVA having a degree of polymerization of usually 50 to 10,000 is preferred. If the degree of polymerization is less than 50, a desired moisture-proof paper cannot be obtained because the desired performance cannot be exhibited as a binder or a moisture-proof layer. When the degree of polymerization is greater than 10,000, the viscosity of the coating liquid for forming the moisture-proof layer becomes too high, making it difficult to handle, and a uniform layer cannot be obtained.

The degree of saponification of the polyvinyl alcohol used in the present invention must be 60 to 99.99 mol%, preferably 70 to 99.9 mol%, and more preferably 80 to 99.5 mol%.
Molar% is more preferred. When the saponification degree is less than 60 mol%, the water solubility is lowered, so that a good coating liquid cannot be obtained, and further, sufficient moisture-proof property cannot be obtained. On the other hand, when the saponification degree is more than 99.99 mol%, the viscosity stability of the coating liquid is insufficient, and the handleability is poor.

The swellable fluoromica-based mineral (B) used in the present invention is typically talc and sodium and / or
Alternatively, a material obtained by subjecting lithium to a silicide or a mixture thereof with a heat treatment may be used. As a specific method, there is, for example, a method disclosed in Japanese Patent Application Laid-Open No. 2-149415. That is, this method uses talc as a starting material, and intercalates sodium ions and / or lithium ions into the starting material to obtain a swellable fluoromica-based mineral. In this method, fluorinated mica-based minerals can be obtained by mixing talc with silicofluoride and / or fluoride and subjecting it to heat treatment at about 700 to 1200 ° C. for a short time in a magnetic crucible. The swellable fluoromica-based mineral used in the present invention is particularly preferably produced by this method.

In order to obtain a swellable fluoromica-based mineral, it is necessary that the metal constituting the silicofluoride or fluoride is sodium or lithium among alkali metals. These alkali metals may be used alone or in combination. Of the alkali metals, potassium is not preferable because swellable fluorine mica-based mica cannot be obtained, but is used in combination with sodium or lithium, and is used for the purpose of adjusting the swellability if the amount is limited. Is also possible. The amount of silicofluoride and / or fluoride mixed with talc is 10% of the whole mixture.
The range of from about 35% by weight to 35% by weight is preferable, and if it is out of this range, the production rate of the swellable fluoromica-based mineral decreases.

The swellable fluoromica-based mineral used in the present invention is typically represented by the following formula. α (MF) ・ β (aMgF2 ・ bMgO) ・ γSiO2

Here, M represents sodium or lithium, α, β, γ, a and b each represent a coefficient,
0.1 ≦ α ≦ 2, 2 ≦ β ≦ 3.5, 3 ≦ γ ≦ 4, 0 ≦ a
≦ 1, 0 ≦ b ≦ 1, a + b = 1.

In the present invention, the term "swelling property" means that a fluoromica-based mineral absorbs polar molecules such as carboxylic acids, alcohols, and water molecules between the layers, thereby increasing the interlayer distance or further swelling to cause super-swelling. Fluorine mica-based mineral represented by the above formula means a property of forming fine particles, and exhibits such a swelling property.

When the polyvinyl alcohol-based polymer (A) and the swellable fluoromica-based mineral (B) of the present invention are used for a moisture-proof layer, the wax used for ordinary moisture-proof paper is substantially contained in these layers. Is preferably not included. Here, “substantially not contained” means that it is not contained at all or contained in a very small amount. In the present invention, when the wax is not substantially contained, the bending strength of the bent portion of the moisture-proof paper hardly decreases, and the disintegration at the time of the collection operation is easy.

The composition comprising the polyvinyl alcohol-based polymer (A) and the swellable fluoromica-based mineral (B) of the present invention contains various polymers (water-soluble polymer or water-soluble polymer) as long as the object of the present invention is not impaired. Polymer emulsion or latex, etc.), fillers, surfactants (nonionic, anionic), lubricants, defoamers, dispersants, wetting agents, pH regulators, ultraviolet absorbers as appropriate for the intended use or performance Can be blended.

Examples of the water-soluble polymer or polymer dispersion include starch and derivatives thereof, cellulose derivatives such as hydroxymethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose and ethylcellulose, arabic gum, polyvinyl alcohol and alkali salts of polyacrylic acid (soda). Salt), an alkali salt of acrylic acid (or methacrylic acid) ester copolymer (such as soda salt), polyvinylpyrrolidone, acrylamide (or methacrylamide) / acrylic acid (or methacrylic acid) ester copolymer, acrylamide (or methacrylic acid) Acrylamide) / acrylic acid ester (or methacrylic acid ester) / acrylic acid (or methacrylic acid) terpolymer, styrene / maleic anhydride copolymer alkali (Soda salt), alkali salt of isobutylene / maleic anhydride copolymer (soda salt, etc.), alkali salt of diisobutylene / maleic anhydride copolymer (soda salt, etc.), polyacrylamide, sodium alginate, gelatin, casein, etc. Water-soluble polymer of polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylate, emulsion such as vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene / vinyl acetate copolymer, styrene / butadiene copolymer Latexes such as a coalesced latex and a styrene / butadiene / acrylic copolymer are exemplified.

As the filler, kaolin, clay, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, silica, colloidal silica, aluminum oxide,
Examples include aluminum hydroxide, synthetic aluminum silicate, synthetic magnesium silicate, polystyrene fine particles, polyvinyl acetate-based fine particles, urea-formalin resin fine particles, and wheat flour.

The paper base material of the present invention can be easily dispersed in water by mechanical disaggregation, for example, chemical pulp such as hardwood kraft pulp and softwood kraft pulp;
Fine paper made from pulp selected from mechanical pulp, etc.
Examples include medium-quality paper, single-gloss kraft paper, Ryoso kraft paper, kraft stretch paper, and the like. 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.

The mixing ratio {(B) / (A)} of the polyvinyl alcohol-based polymer (A) and the swellable fluoromica-based mineral (B) in the moisture-proof layer of the moisture-proof paper is 0.1 to 20.
A range of 0 (weight ratio) is preferable. More preferably,
It is in the range of 0.1 to 100 (weight ratio). If the amount is less than 0.1 part by weight, the moisture-proof effect intended by the present invention is not sufficient,
If the amount is more than 00 parts by weight, adverse effects such as a large decrease in toughness, an increase in viscosity and difficulty in coating, and an easy formation of pinholes are undesirably caused.

The coating amount of the moisture-proof layer is determined by the following equation.
S Z0208 (cup method) 100 g /
It is preferable to determine the coating amount so as to be not more than m2 · 24 hr. Specifically, the range of the coating amount is 1 to 50
g / m2 is preferred. More preferably, 5 to 40 g / m
2. If it is less than 1 g / m2, the moisture permeability is 100 g / m2.
It becomes larger than 2.24 hr. Further, if it is more than 50 g / m2, the moisture permeability does not improve, and rather, foaming in the waste paper collecting step and difficulty in drainage treatment occur. The moisture permeability is preferably 90 g / m2 · 24 hr or less, and more preferably 60 g / m2 · 24 hr or less.

The coating equipment for the moisture-proof layer can be arbitrarily selected from an air knife coater, a bar coater, a roll coater, a blade coater and the like, and in particular, such as a blade coater, a bar coater and an air knife coater. The coating method is preferable because it tends to promote the orientation of the swellable fluoromica-based mineral of the tabular pigment.

[0028]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. In the examples, unless otherwise noted.
“%” And “parts” mean “% by weight” and “parts by weight”, respectively.

Example 1 1) Preparation of Coating Solution for Moisture Proof Layer Ethylene vinyl alcohol copolymer (A) having 5.1 mol% of ethylene unit, 98.5 mol% of saponification degree of vinyl ester portion and polymerization degree of 1550 Then, 0.15 wt% of an antifoaming agent (Jorsin LB-D) was added to prepare a 10% aqueous solution (a). Swellable Fluorine Mica (Somasif ME-1)
(00: manufactured by Corp Chemical) (B) was dispersed in water so as to have a concentration of 6%, and was subjected to an ultrasonic cleaner for 2 hours to prepare a dispersion (b). While stirring 800 parts of the aqueous solution (a) at room temperature, 333 parts of the solution (b) was slowly added, and then a required amount of distilled water was added to prepare a coating solution having a concentration of 7%. / (A) = 20/80 °. 2) Coating of coating liquid for moisture-proof layer The above coating liquid was coated on unbleached kraft paper by a bar coater at 30 g / m 2, and dried at 110 ° C. for 1 minute.
A moisture-proof paper was obtained. The moisture permeability of the paper is 56g / m2 · 24hr
{Based on JIS Z0208 (cup method) B method}. 3) Disintegration 8 g of moisture-proof paper of about 3 cm square was stirred for 1 minute and 30 seconds with 500 ml of water with a household mixer (a blade was shaved off with a file so as not to cut the fiber). The obtained slurry was used as a handmade sheet having a basis weight of 60 g / m ^{2 in} a laboratory handmade machine. The presence or absence of undisintegrated materials (film pieces, paper pieces) was visually evaluated.

Example 2 A coating liquid was prepared in the same manner as in Example 1 except that the polyvinyl alcohol shown in Table 1 was used instead of the polyvinyl alcohol polymer (A) used in Example 1. It was adjusted to produce a moisture-proof paper. Table 1 shows the results. Example 3 An antifoaming agent (Jorsin LB-D) was added to an ethylene vinyl alcohol copolymer (A) having an ethylene unit of 5.1 mol%, a degree of saponification of a vinyl ester portion of 99.3 mol%, and a degree of polymerization of 550. A 10% aqueous solution was prepared by adding 0.15 wt% (a). Swellable fluorine mica (Somasif ME-10)
0: manufactured by Corp Chemical Co., Ltd.) (B) was dispersed in water to a concentration of 6%, and was subjected to an ultrasonic cleaner for 2 hours to prepare a dispersion liquid (b). While stirring 800 parts of the aqueous solution (a) at room temperature, 333 parts of the solution (b) were slowly added to the mixture to give a concentration of 8.
8% coating liquid was prepared. {Blend ratio: (B) /
(A) = 20/80 °. Furthermore, synthetic resin latex 0
X1060 (SBR latex: manufactured by Nippon Zeon Co., Ltd.
A coating solution having a concentration of 14% was prepared by mixing 160 parts by weight (solid content: 50%) {weight ratio: (B) / (A) / synthetic resin latex = 10/40/40}. This coating solution is hand-coated on unbleached kraft paper with a Meyer bar so as to have a coating amount of 30 g / m2 as a solid content, and then dried at 110 ° C. for 1 minute using a hot-air circulating drier to obtain moisture-proof paper. Was manufactured.
Further, the moisture-proof paper obtained in the above Examples 1 to 3 was JIS Z
After performing a bending test according to 6.4.2 of 1503, the moisture permeability was measured, and almost no difference was observed from the values shown in Table 1 (values before bending).

Comparative Examples 1 and 2 Instead of the polyvinyl alcohol polymer (A) and the swellable fluoromica mineral (B) used in Example 1,
A coating solution was prepared in the same manner as in Example 1 except that polyvinyl alcohol and a pigment shown in Table 1 were used, and a moisture-proof paper was produced. Table 1 shows the results.

Comparative Example 3 Polyethylene was laminated to unbleached kraft paper to a thickness of 15 μm to produce a moisture-proof paper. Table 1 shows the results.

[0033]

[Table 1]

[0034]

As is clear from the above examples, the moisture-proof paper of the present invention can be handled in the same manner as polyethylene-laminated wrapping paper, and has excellent moisture-proof properties.
Further, since the re-disintegration is easy, the recovery of the used paper is easy. When substantially no wax is contained, even if the obtained moisture-proof paper is bent, the moisture-proof property hardly decreases.

Claims (4)

[Claims] 1. A moisture-proof paper having a paper substrate as a support, wherein at least one surface of the paper substrate is formed from a polyvinyl alcohol-based polymer (A) and a swellable fluoromica-based mineral (B). With layer and moisture permeability 100g
/ M2 · 24 hr or less. 2. A moisture-proof paper having a paper substrate as a support, wherein at least one surface of the paper substrate is formed from a polyvinyl alcohol-based polymer (A) and a swellable fluoromica-based mineral (B), A moisture-proof paper having a layer substantially free of wax and having a moisture permeability of 100 g / m2 · 24 hr or less. 3. The moisture-proof paper according to claim 1, wherein the polyvinyl alcohol polymer (A) is a vinyl alcohol polymer containing 1 to 20 mol% of an α-olefin having 4 or less carbon atoms. 4. The moisture-proof paper according to claim 1, wherein the moisture-proof paper is a recoverable moisture-proof paper.