JP2000303386A - Barrier moisture-proof laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a gas barrier moistureproof laminate having excellent gas barrier properties and moistureproof properties, and capable of being easily disaggregated and reclaimed after use by forming a gas barrier layer on the surface of a paper supporter, and further laminating a moistureproof layer comprising a tabular pigment and a synthetic resin latex thereon. SOLUTION: A gas barrier layer consisting essentially of microfibrous cellulose having >=300% water retentivity (JAPAN TAPPI No. 26-78) is formed at least on one surface of a paper supporter, and a moistureproof layer obtained by formulating a tabular pigment treated with a coupling agent and having >=10 aspect ratio, e.g. a phyllosilicate compound such as white mica, sericite and phlogopite, with a synthetic resin latex such as the styrene-butadiene-based one in a weight ratio of (30:70)-(70:30), and further adding an active hydrogen- reactive compound thereto, is coated on the resultant product to provide the objective moistureproof laminate with barrier properties.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a material used for packaging of foods, medicines, electronic parts, etc., or for various paper containers, which has high gas barrier properties (especially oxygen barrier properties) and excellent moisture-proof properties. The present invention relates to a barrier moisture-proof laminate which can also be easily disaggregated and can be recycled as used paper after use.

[0002]

2. Description of the Related Art In recent years, packaging materials have not only the function of simply wrapping things, but also have a high plus α function such as various freshness preserving packaging materials and retort sterilizing packaging materials that can be distributed at room temperature. Packaging materials are being developed and marketed one after another. The functions required of these packaging materials are diverse, but especially when the contents are foods, medical products, etc., high moisture-proof and gas-barrier properties, especially oxygen barrier properties, are important to prevent deterioration of the quality. Come. Usually, a substrate having such a barrier property is coated with a gas barrier resin such as a polyvinylidene chloride resin or an ethylene-vinyl alcohol copolymer, a polyacrylonitrile on a substrate such as a polyolefin-based film or a polyester film,
Alternatively, a laminated product, a product obtained by laminating films, or a product obtained by combining these as a co-extruded film is used. Among them, particularly polyvinyl alcohol and ethylene-vinyl alcohol copolymer,
Since they exhibit extremely high oxygen barrier properties due to strong intermolecular cohesion due to hydrogen bonding and are chlorine-free, they have recently been receiving attention as the most suitable base materials for packaging materials requiring general-purpose barrier properties. However, these hydrogen-bonding substrates also suffer from the drawback that when placed in high humidity, moisture is adsorbed to the hydrophilic groups in the resin and the oxygen barrier properties are greatly reduced due to the weak intermolecular cohesion. is there.

For this reason, when these hydrogen-bonding substrates are used as a packaging material, generally, a substrate having low water vapor permeability, for example, a polyolefin film such as polypropylene or polyethylene, or a physical or A method of reducing the partial pressure of water vapor on the surface of the hydrogen bonding base material and reducing the influence of humidity by forming a multilayer with a film subjected to a chemical treatment (metal deposition, CVD, or the like) has been adopted. Examples of packaging materials that successfully apply the hydrogen bonding substrate having such problems include paper supports, saponified ethylene-vinyl acetate copolymers, partially saponified ethylene-vinyl acetate copolymers, and polyolefin-based resins. Multi-layer film laminated in the order of film
JP-A-2-24948) and a laminate in which a synthetic resin film / a saponified ethylene-vinyl acetate copolymer / polyolefin film is laminated in this order, and an adhesive layer containing a water-absorbing resin is provided between each layer (Japanese Patent Laid-Open No. JP-A-63-120643), a saponified ethylene-vinyl acetate copolymer, to which an oxidation catalyst such as a transition metal compound is added, mixed with a polyolefin resin or the like, and melt-injected and molded (Japanese Patent Laid-Open No. 4-21)
No. 1444) are disclosed. However, most of such barrier base materials have a laminated structure with a plastic film, and those obtained by melt injection molding as a mixture thereof, and even when a vinyl alcohol-based resin or the like is used alone, high humidity The oxygen barrier properties below have not yet reached a satisfactory level. Further, in recent years, as environmental problems have become more serious, the treatment of packaging waste has been taken up as a social problem, and the industry has been forced to respond. Although the above-mentioned packaging materials are all excellent in moisture-proof / gas-barrier properties, no consideration was given to recyclability. Against the background of such social trends,
Recyclable as waste paper, moisture proof and gas barrier properties,
In particular, there is still a strong need for packaging materials having oxygen barrier properties.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an easily disintegrating barrier laminate which has both excellent moisture-proofing properties and gas barrier properties, especially oxygen barrier properties, and which is easy to disintegrate and regenerate after use. Is what you do.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies in view of the present situation, and as a result, have found that the above-mentioned problems can be solved by adopting the following constitution.

That is, a first aspect of the present invention is that a fine fibrous cellulose (JAPAN TA) is formed on at least one surface of a paper support.
Gas barrier layer composed mainly of a gas barrier layer having a water retention capacity of 300% or more according to PPI No. 26-78) and a moisture barrier layer composed of a flat pigment and a synthetic resin latex are sequentially laminated. It is a laminate.

A second aspect of the present invention is the barrier moisture-proof laminate according to the preceding paragraph, wherein the plate-like pigment used in the moisture-proof layer is treated with a coupling agent.

[0008] The third aspect of the present invention is the barrier moisture-proof laminate according to the above-mentioned item, characterized in that the moisture-proof layer contains an active hydrogen-reactive compound.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
In the present invention, microfibrillar cellulose (Microfibrillated) is formed as a first layer on a paper support.
(Cellulose: hereinafter referred to as MFC). The layer mainly composed of MFC has excellent gas barrier properties, especially oxygen barrier properties, due to strong hydrogen bonding. Generally, MFCs are manufactured by a method combining chemical treatment and mechanical grinding, for example, by passing an aqueous suspension of fibrous cellulose through a small diameter orifice at a high pressure with a pressure difference of at least 3000 psi. That is, a method of treating a fibrous cellulose suspension with a high-pressure homogenizer (Japanese Patent Publication No. 60-19921, etc.) and a method of treating an aqueous suspension of pulp with a sand mill lightly (JP-A-4-1818).
No. 6), and a method of wet-grinding fibrous cellulose pretreated by an enzyme or a chemical treatment with a vibrating mill pulverizer (JP-A-6-10288). Among the above-mentioned methods, as a method for producing an MFC suitable for the present invention, a fibrous cellulose or a suspension thereof is treated with a sand mill or a vibration mill through a pulverizing medium (beads or balls). A method in which a pulp fiber is subjected to a shearing action, an impact action, a friction action, or the like and mechanically dry- or wet-pulverized is preferably used. With such a method, processing efficiency is high,
Further, the obtained MFC has high water holding power and is inexpensive. As a pulp fiber as a raw material of these MFCs, bleached or unbleached coniferous or hardwood chemical pulp, mechanical pulp, dissolved pulp, waste paper pulp, or the like can be appropriately used.

As the MFC used in the present invention, those having a water holding power of 300% or more are preferably used. Here, the water holding power is a value calculated by a measuring method according to JAPAN TAPPI No. 26-78. Pulp fibers have a higher surface area as the fibers are refined, have a higher affinity for water, have a higher viscosity, and thus have a higher ability to retain water. Conversely, it can be said that the finer the fiber, the higher the value of the water retention force. In addition, the water holding power of beating wood pulp fibers in ordinary papermaking is determined by beating hardwood kraft pulp (unbeaten freeness 620 ml, water holding power 105%) with a refiner at a treatment concentration of 2% and freeness 440 ml.
, The water holding power is about 139%. In the present invention, a slurry obtained by adjusting the above-mentioned MFC having a water holding power of 300% or more to a concentration suitable for actual coating is used as a gas barrier coating. In the present invention, when forming the gas barrier layer, various anionic, nonionic, cationic or amphoteric paper strength enhancers, sizing agents, and the like are appropriately selected and added to the gas barrier paint or coated on the surface. Etc. can be used. Since MFC is originally a cellulose fiber, it does not adversely affect the recyclability of the laminate. However, the gas barrier layer by MFC
When placed under high humidity, there is a drawback that moisture is adsorbed on the hydrophilic group, and the hydrogen bonding is weakened, so that the barrier property is greatly reduced.

Therefore, in the present invention, a moisture-proof layer comprising a flat pigment and a synthetic resin latex is further provided as a second layer on the gas barrier layer. The present inventors have previously formed a moisture-proof layer obtained by mixing a flat pigment with a synthetic resin latex with respect to such a moisture-proof layer. Since the plate-like pigments are arranged and laminated in parallel to the surface of the coating layer, the water vapor in the coating layer is transmitted while bypassing the plate-like pigments, resulting in a large required water vapor transmission distance. For this reason, it has been found that a moisture-proof layer having excellent moisture-proof performance can be obtained (Japanese Patent Application Laid-Open No. 9-21096). It has also been found that the addition of a crosslinking agent or a coupling agent to these mixed paints can further improve moisture-proof performance. In this case, the cross-linking agent increases the cross-linking density of the synthetic resin latex, and the coupling agent increases the affinity between the synthetic resin latex and the plate-like pigment to reduce minute voids at the interface between the two. It is thought that the moisture permeation performance is greatly improved by obstructing the permeation of water (Japanese Patent Application No. 7-330251).

The tabular pigment used in the present invention is not particularly limited as long as it retains tabularity (tabular shape) even after coating processing. Particularly, a phyllosilicate compound (a layered silicate compound having a layered structure) is preferable. Those belonging to the phyllosilicate compounds are plate-like or flaky and have distinct cleavages, and include kaolinite (kaolin mineral), mica, brittle mica, pyrophyllite, talc,
Examples include smectite, vermiculite, chlorite, septe chlorite, serpentine, stilp nomelane, and montmorillonite. Of these, mica and talc are particularly preferred. Mica tribe includes muscovite (muscovite), sericite (sericite), biotite (flokopite), biotite (biotite), fluorophlogopite (artificial mica), red mica, soda mica, vanadin mica, illite, Chin mica, paragonite, brittle mica and the like. Among these phyllosilicate compounds, especially muscovite, sericite,
And phlogopite are preferably used in view of the particle size, aspect ratio and the like. In the present invention, the more preferable average particle diameter (measured value by a laser diffraction method) range of these tabular pigments is 1 μm to 100 μm. When the average particle size is 1 μm or less, the orientation of the tabular pigment in the coating layer is unlikely to be parallel to the paper support, and
m or more of the tabular pigment protrudes from the moisture-proof layer when the thickness of the tabular pigment becomes about several μm,
Since the number of layers of the oriented tabular pigment in the moisture-proof layer is reduced, the effect of improving the moisture-proof performance is reduced. Also,
The preferred aspect ratio (the 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, and particularly preferably a tabular pigment having an aspect ratio of 10 or more. If the aspect ratio is 5 or less, the film cannot be oriented in parallel to the coating surface, so that the moisture-proof performance is inferior. The larger the aspect ratio, the larger the number of layers of the tabular pigment in the coating layer, so that high moisture-proof performance is exhibited.

The synthetic resin latex used in the present invention includes styrene-butadiene latex (SBR), acryl-styrene latex, methacrylate-butadiene latex, acrylonitrile-butadiene latex, etc., but has good water resistance and good elongation. Styrene-
Butadiene latex is preferred. Styrene-butadiene latex is styrene modified with (meth) acrylic acid, (meth) acrylic acid ester, (meth) acrylonitrile, (meth) acrylic acid glycidyl, (meth) acrylic acid amide, (meth) acrylic glycidyl ether, etc. -Butadiene latex (modified SBR) may be used. The mixing ratio (solid ratio) (solid ratio) of the flat pigment and the synthetic resin latex used in the present invention is 30:70 to 70:30, preferably 40:60.
65:35.

Examples of the coupling agent used in the present invention include a silane coupling agent containing Si in the hydrophilic group, a titanate coupling agent containing Ti in the hydrophilic group, and an aluminum coupling agent containing Al in the hydrophilic group. Is mentioned. The structure of the coupling agent is roughly classified into a hydrophilic group that interacts with an inorganic compound such as a plate-like pigment, for example, a phyllosilicate compound, and a hydrophobic group that interacts with an organic compound such as a resin. The portion is obtained by hydrolyzing a metal element such as Ti or Al or an alkoxy group bonded to Si. The reactivity between the hydrophilic group and the inorganic compound is high when the inorganic compound has a hydroxyl group on the surface, such as glass, silica, alumina, talc, clay, and mica. The titanate coupling agent has high reactivity even when the inorganic compound is calcium carbonate, barium sulfate, or calcium sulfate.
On the other hand, as for the hydrophobic group portion of the coupling agent, when the hydrophobic group portion is an organic oligomer, a high molecular organic film is formed on the surface of the inorganic compound, and the surface is completely hydrophobized to enhance the adhesiveness with the resin matrix. effective. Also,
When the hydrophobic group has a reactive organic functional group such as an epoxy group, a vinyl group, or an amino group, the functional group and the reactive functional group of the resin matrix are cross-linked to further enhance the adhesiveness to the resin matrix. Therefore, the composition of the hydrophobic group portion of the coupling agent is determined by the compatibility with the resin as the affinity partner. Examples of such a coupling agent include 2-glycidoxyethyltrimethoxysilane, 2-glycidoxyethyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2- (3,4 epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4 epoxycyclohexyl) ethyltriethoxysilane, 3-
(3,4 epoxycyclohexyl) ethyltrimethoxysilane, 2-aminoethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3- [N- (2-aminoethyl)
Amino] ethyltrimethoxysilane, 3- [N- (2-
Aminoethyl) amino] propyltrimethoxysilane,
3- [N- (2-aminoethyl) amino] propyltriethoxysilane, 3- [N- (2-aminoethyl) amino] propylmethyldimethoxysilane, 2-methacryloxyethyltrimethoxysilane, 2-methacryloxyethyl Triethoxysilane, 2-acryloxyethyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, methyltriethoxysilane, 2-mercaptoethyl Trimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, vinylacetoxysilane, 2-chloroethyltrimethoxysilane, 2-chloroethyltriethoxysilane,
Examples thereof include 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, γ-anilinopropyltrimethoxysilane, and isopropyltri (N-aminoethylaminoethyl) titanate. In addition, as a surface treatment method of the tabular pigment with these coupling agents, there are an integral blend method and a pretreatment method,
It can be adopted arbitrarily as needed. The integral blending method is a method in which a coupling agent is directly added to a coating liquid containing a tabular pigment and a synthetic resin latex.
Compared with the pretreatment method, the workability is excellent because a separate step is not required. In addition, the pretreatment method is a method in which a flat pigment is previously treated with a coupling agent before producing a moisture-proof paint. Excellent processing effect compared to the integral blend method. The amount of coupling agent added is 10
0.1 to 5 parts by weight (solid content or active ingredient), preferably 0.5 to 2 parts by weight, based on 0 part by weight (solid content). When the addition amount is less than 0.1 part by weight, the coating of the surface of the flat pigment with the coupling agent is insufficient, which is not preferable. When the addition amount exceeds 5 parts by weight, the effect of the coupling agent reaches a plateau and is uneconomical. It is. The planar pigment thus subjected to the coupling treatment has an increased hydrophobicity on the surface, so that when it is used as an aqueous dispersion, it may be thickened and cannot be applied, or the dispersion may be poor and aggregates may be generated. In this case, the dispersion is performed using a surfactant, a polyacrylic acid-based dispersant, or a wetting agent such as isopropyl alcohol or sodium dialkyl sulfosuccinate.

The latex crosslinking agent used in the present invention reacts with a hydrophilic functional group such as a carboxyl group, an amide group or a hydroxyl group contained in the synthetic resin latex to crosslink the synthetic resin latex to polymerize it (three-dimensional network structure). ). Examples of such a crosslinking agent include (1) a compound having a methylol group and causing a dehydration reaction with the hydrophilic functional group (such as a melamine-formaldehyde condensation reaction product), and (2) a compound having an aldehyde group and the hydrophilic functional group. (3) having an epoxy group and causing a ring-opening addition reaction with the hydrophilic functional group (eg, a polyglycidyl ether compound), and (4) having a polyvalent metal. (5) a compound which forms a coordination bond and a covalent bond with the above-mentioned hydrophilic functional group (such as zirconium carbonate); (5) a compound which is cationic in an aqueous solution and forms an ionic bond with an anionic functional group (such as a polyamidoamine polyurea resin) )and so on. The compounding amount of the latex crosslinking agent is synthetic resin latex 1
The amount is preferably 0.01 to 10 parts by weight (solid content or active ingredient), and more preferably 0.1 to 5 parts by weight, based on 00 parts by weight (solid content). When the blending amount of the crosslinking agent is less than 0.01 part by weight, the reactivity between the crosslinking agent and the hydrophilic functional group is remarkably reduced. It is not preferable because problems such as peaking out and unreacted crosslinking agent are precipitated.

The above materials are mixed to form a moisture-proof paint. If necessary, a dispersant such as polycarboxylic acid, an antifoaming agent, a surfactant, a water retention agent, a color adjusting agent, etc. may be added. Or you can. Next, the gas barrier coating and the moisture-proof coating are sequentially applied on a paper support by a conventional method to form a gas barrier layer and a moisture-proof layer. By providing a moisture-proof layer on the gas barrier layer, the laminate not only obtains moisture-proof properties, but also protects the gas barrier layer of the present invention, which is greatly reduced under high humidity, and has an effect of maintaining good barrier properties. . Therefore, the lamination order of each layer is preferably the configuration of paper support / gas barrier layer / moisture-proof layer. If necessary, the paper support may be coated with a moisture-proof layer once, and then the gas barrier layer and the moisture-proof layer may be sequentially laminated. There is no particular limitation on the coating equipment that can be used.In particular, when coating a moisture-proof layer, a coating method that scrapes the coating surface such as a blade coater, a bar coater, or an air knife coater is more suitable for a flat pigment. Is more preferable in that it tends to promote the orientation of In addition, the coating amount of each gas barrier layer and moisture barrier layer can be arbitrarily set according to the required performance, but the range of oxygen permeability that can be used for a wider application as a laminate having gas barrier properties is: 1
50 g / m ² / 24hr or less, more preferably 100 g / m ² / 24hr
In order to obtain such a laminate of the present invention, the coating amount of the gas barrier layer is desirably 10 g / m ² or more. However, when the coating amount exceeds 50 g / m ² , the oxygen barrier property tends to reach a plateau. The range of moisture permeability that can be used for a wider range of applications as a laminated paper having moisture resistance is 50 g / m ^2.
/ 24 hr or less, more preferably not more than 45g / m ² / 24hr, coating amount of the moisture barrier in order to obtain such present invention laminate is further desirable that the 10 g / m ² or more. However, when the coating amount exceeds 50 g / m ² , not only does the moisture resistance level off, but the disintegration may be poor.

The paper support used in the present invention is not particularly limited as long as it is mainly composed of pulp which is easily dispersible in water by mechanical disaggregation, but is generally used bleached or unbleached. Kraft paper (acid paper or neutral paper), or paperboard used for cardboard, building materials, white balls, chip balls, and the like are suitable. Most preferably, it is one-side glossy paper which has been forcibly dried with a Yankee dryer or the like, or bleached / unbleached kraft paper which has been subjected to a calendar treatment. When a paper support having a highly smooth surface is used as described above, particularly in the moisture-proof layer, the orientation of the plate-like pigment in the thickness direction can be easily uniformly and parallelly arranged without partially disturbing the coating surface. Therefore, the moisture-proof performance is significantly improved. Further, such a paper support has a small expansion and contraction of the base material due to a change in humidity, so that the influence of distortion on the gas barrier layer and the moisture-proof layer is reduced, and as a result, stable gas barrier properties and moisture-proof properties can be maintained. It becomes possible.

[0018]

The present invention will be described in detail with reference to the following examples. Unless otherwise specified, “parts” and “%” represent “parts by weight” and “% by weight”, respectively.

Example 1 Hardwood Kraft Pulp
A 5% water suspension was mixed with an experimental vibration mill (trade name: MB-1 type,
Wet pulverization treatment was performed using Chuo Kakoki Co., Ltd.) to produce an MFC having a water holding power of 350%, and further concentrated to a 5% slurry using a mesh to obtain a gas barrier paint.

Separately, phlogopite (trade name: W40, manufactured by Repco Co., Ltd., average particle size 25 μm) was used as a tabular pigment.
m, aspect ratio 30 to 40) 50 parts by weight, and styrene-butadiene copolymer latex (trade name: LX407S1X2, ZEON CORPORATION) as a synthetic resin latex
0.5% by weight of ammonia and 0.5 part by weight of a polyamide polyurea-formaldehyde condensation reaction product (trade name: SR302, manufactured by Sumitomo Chemical Co., Ltd.) with respect to 50 parts by weight of a solid content concentration: 49%. Was mixed and stirred, and further adjusted to a solid content concentration of 50% to obtain a moisture-proof coating. On the glossy side of unbleached kraft paper having a basis weight of 45 g / m ² , the gas barrier paint was overcoated 2-3 times using a Mayer bar so that the coating amount was 20 g / m ^2. A gas barrier layer was formed on the base paper. At this time, a cylinder dryer heated to 150 ° C for each coating (trade name: Auto Dryer L
3, manufactured by Japo Corporation). Next, a moisture-proof coating is applied on the gas barrier layer using a Mayer bar so that the coating amount is 20 g / m ^2, and is applied at 110 ° C. for 80 seconds using a hot-air circulation dryer. After drying, a barrier moisture-proof laminate of the present invention was obtained.

Example 2 A gas-barrier coating obtained in the same manner as in Example 1 was applied to the glossy side of a single-gloss unbleached kraft paper having a basis weight of 45 g / m ² using a Mayer bar. A barrier moisture-proof laminate was obtained in the same manner as in Example 1, except that the coating was repeated about 2 to 3 times so that the amount was 12 g / m ² .

Example 3 A barrier moisture-proof laminate was obtained in the same manner as in Example 1 except that an MFC having a water retention capacity of 460% was prepared and used as an oxygen barrier paint.

<Example 4> As a tabular pigment, muscovite (trade name: AB32, manufactured by Mika Yamaguchi Co., Ltd., average particle size 2)
0 μm, aspect ratio 20-30) and 54 parts by weight of styrene-butadiene copolymer latex (trade name: LX407S1X2, manufactured by Zeon Corporation, solid content concentration: 49%) as a synthetic resin latex, 0.6 parts by weight of ammonia and 0.5 parts by weight of an aminosilane coupling agent (trade name: KBM603, manufactured by Shin-Etsu Chemical Co., Ltd., 99% or more of active ingredient) were mixed and stirred to adjust the solid content concentration to 50%. A barrier moisture-proof laminate was obtained in the same manner as in Example 1, except that the moisture-proof layer was formed using a moisture-proof paint.

<Example 5> The coating amount of the moisture-proof paint was 12 g /
except that the m ² was obtained a barrier moistureproof laminate in the same manner as in Example 1.

Example 6 The coating amount of the moisture-proof paint was 8 g / m ^2.
A laminate was obtained in the same manner as in Example 1 except that the coating was performed so as to be as follows.

Comparative Example 1 A polyethylene terephthalate film having a thickness of 50 μm was used as Comparative Example 1.

Comparative Example 2 bleached kraft paper (basis weight 70 g /
m ² ), polyethylene-laminated paper in which polyethylene was laminated on one side at 20 μm was used as a barrier laminate.

Comparative Example 3 Hardwood Kraft Pulp
A 5% aqueous suspension was wet-pulverized using an experimental vibration mill to produce an MFC with a water holding power of 200%, and the same procedure as in Example 1 was carried out except that it was used as an oxygen barrier paint. I got

<Comparative Example 4> Calcium carbonate which is not a tabular pigment as a pigment (trade name: Softon BF-100, manufactured by Bihoku Powder Chemical Co., Ltd., average particle diameter 3.5 μm, aspect ratio 2)
Below) 50 parts by weight and a styrene-butadiene copolymer latex (trade name: LX40) as a synthetic resin latex
7S1X2, manufactured by Zeon Corporation, solid content concentration: 49
%) With 50 parts by weight of ammonia and 0.5 part by weight of a polyamide polyurea-formaldehyde condensation reaction product (trade name: SR302, manufactured by Sumitomo Chemical Co., Ltd.) with 0.5 part by weight and mixing and stirring to prevent moisture. A laminate was obtained in the same manner as in Example 1 except that a water-soluble paint was used.

The samples obtained in Examples 1 to 6 and Comparative Examples 1 to 4 were evaluated for disintegration, moisture permeability and oxygen permeability by the following test methods, and the results are shown in Tables 1 and 2. Show.

(Disintegration test) Using a TAPPI standard disintegrator, 45 g of a 3 cm square sample was stirred with 1500 ml of water for 10 minutes. A hand-made sheet having a basis weight of 70 g / m ² was prepared from the obtained pulp slurry. When the size of the defibrated pieces of the undisintegrated material was 1 mm × 1 mm or less, the sample was evaluated as ○, and when the size of the defibrated pieces exceeded the size, the sample was evaluated as ×. (Measurement of Moisture Permeability) The measurement was carried out according to JIS Z0208 B method (cup method) with the coated surface outside (high humidity side). (Measurement of Oxygen Permeability) According to JIS K7126 B method (isobaric method), the measurement was performed in a dry state with the coated surface facing the oxygen detector.

[0032]

[Table 1]

[0033]

[Table 2]

As is clear from Table 2, the easily disintegratable barrier laminates of the present invention have good disintegration, oxygen barrier properties, and moisture resistance (Examples 1 to 6).
On the other hand, when polymer plastic is used as the barrier substrate, the disintegration is poor, and the oxygen barrier properties of polyethylene laminated paper are significantly poor (Comparative Examples 1 and 2). When the water holding power of the MFC is less than 300%, an effective oxygen barrier property cannot be obtained (Comparative Example 3), and when the pigment used for the moisture-proof layer does not have flatness, it is satisfactory. No moisture resistance is obtained (Comparative Example 4).

[0035]

As described above, according to the present invention, it is possible to obtain an easily disintegrating barrier laminate having both excellent moisture-proofing properties and gas barrier properties, especially oxygen barrier properties, and easy to disintegrate and regenerate after use. Can be.

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Claims (3)

[Claims] 1. A gas-barrier layer mainly composed of fine fibrous cellulose (water holding power of 300% or more according to JAPAN TAPPI No. 26-78) and a flat pigment on at least one surface of a paper support. A barrier moisture-proof laminate comprising a moisture-proof layer made of a synthetic resin latex sequentially laminated. 2. The method according to claim 1, wherein the tabular pigment used in the moisture-proof layer is treated with a coupling agent.
The barrier moisture-proof laminate according to the above. 3. The barrier moisture-proof laminate according to claim 1, wherein the moisture-proof layer contains an active hydrogen-reactive compound.