JPH04334447A - Manufacture of water vapor proof packaging material - Google Patents

Abstract

PURPOSE:To obtain water vapor barrier properties, which are high over a long period of time by a method wherein polymer water dispersions, the lowest film-forming temperature of which is a specified one, are applied on the surface of paper so as to form first layer and, after that, the water dispersions of wax and polymer are applied on the first layer and dried so as to form second layer. CONSTITUTION:The water vapor proof packaging material concerned has the integral film (or composite film) of two films, one of which is moisture permeable polymer film formed on the surface of paper as base material and the other of which is wax-containing film (or water vapor proof film consisting of wax and polymer) formed out of the moisture permeable polymer film. At the manufacturing of the packaging material concerned, firstly, polymer emulsion, the lowest film-forming temperature of which is 1 deg.C or higher, is applied on the surface of paper and dried so as to form moisture permeable polymer film 2 as first layer. After that, the emulsion of wax and polymer is applied on the first layer and thermally dried so as to form wax-containing film as second layer. Thus, the water vapor proofness over a long period of time is obtained and, at the same time, the reuse of the paper becomes possible.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention has a moisture permeability (measured according to JIS Z0208) of 3 at a temperature of 40°C and a relative humidity of 90%.
The present invention relates to a method for manufacturing a moisture-proof packaging material based on resource-saving and pollution-free paper that achieves high moisture resistance of less than g/m2.24 hours. More specifically, the present invention relates to a method for producing a moisture-proof packaging material based on paper, which can be used for direct packaging of drugs, foods, etc., and for long-term moisture-proof retention.

0002

2. Description of the Related Art A general-purpose crystalline synthetic resin film having moisture-proof properties and heat-sealing strength is used in general moisture-proof packaging materials. However, for films such as polyethylene or unstretched polypropylene, moisture permeability (measured according to JIS Z0208 at a temperature of 40°C and a relative humidity of 90%; hereinafter, moisture permeability values are based on the same method unless otherwise specified). is a two-digit value, and even films made of polyvinyl chloride, polyvinyl chloride-polyvinylidene chloride copolymer, etc., which are said to have excellent moisture resistance, have a moisture permeability of about 3 to 6 g/m2.24 hours. However, even with a moisture permeability of about 3 to 6 g/m2 for 24 hours, chlorine-containing materials have limitations when used as general moisture-proof packaging materials for foods, etc. The moisture permeability of the crystalline synthetic resin film alone is said to be at least about 10 g/m 2 ·24 h. Therefore, in order to obtain higher moisture resistance, it is necessary to make the film thicker, for example, 250 microns or more.

[0003] For this reason, when greater moisture resistance is required, a crystalline synthetic resin is further laminated on top of a crystalline synthetic resin film that has heat sealability and food sanitation properties, or aluminum foil is vapor-deposited. A method of laminating layers is adopted. Combinations of resins to be laminated include biaxially oriented polypropylene/aluminum vapor-deposited polyvinylidene chloride coated polypropylene, aluminum vapor-deposited polyethylene terephthalate/polypropylene, and polyethylene/aluminum foil. However, these crystalline synthetic resin film packaging materials cannot be recovered and reused, resulting in a waste of resources, and the only way to dispose of them after use is by incinerating them or burying them in a landfill. Moreover, if packaging materials contain chlorine-containing resins such as polyvinyl chloride and polyvinylidene chloride, chlorine gas is generated during incineration, damaging the incinerator, and the dioxin generated during that process can be harmful to humans. and cause industrial pollution.

[0004] Furthermore, since the crystalline synthetic resin film itself does not decompose or disintegrate in packaging materials buried in landfills, they remain in the landfills and cause environmental pollution. Therefore, a moisture-proof packaging material that can save resources and energy by reusing materials through a recycling system and does not cause industrial pollution, that is, a moisture-proof packaging material in which a moisture-proof layer is formed on paper, has been proposed. Kosho 55-
22597, Japanese Patent Application Laid-open No. 59-66598, Japanese Patent Publication No. 2-1671). These moisture-proof packaging materials attempt to improve the insufficient moisture-proof properties of wax by providing a layer of a homogeneous mixture of wax and a polymeric substance. That is, in order to improve the moisture-proofing properties of a wax-containing moisture-proof layer, it is necessary to form a film by applying a uniform mixture of wax and a polymeric substance. However, the moisture permeability of synthetic rubber and wax emulsion coatings is 18 to 500 g/m2.
- Low moisture permeability of 24 hours
2597, Japanese Patent Application Laid-Open No. 59-66598), it is not a substitute for crystalline synthetic resin film packaging materials.

[0005] Furthermore, since the coating amount, that is, the coating layer thickness, which greatly changes the moisture permeability during moisture permeability measurement, is unknown, it is unclear how high moisture resistance is actually achieved. It is said that a certain degree of high moisture resistance can be imparted to cardboard base paper by coating a layer of a mixed emulsion (90-50:10-50) of acrylic emulsion and wax emulsion (Japanese Patent Publication No. 2-1671). . However, despite such proposals, there is a paper-based highly moisture-proof moisture-proof packaging material that can be used in place of crystalline synthetic resin film packaging materials, and which can be used in actual use. Things didn't exist. for that,
From the viewpoint of resource saving and pollution-free production, it is possible to realize highly moisture-proof paper-based packaging materials that can replace crystalline synthetic resin film packaging materials and be used for long-term storage of foods, medicines, etc. It was wanted.

[0006]

[Problems to be Solved by the Invention] The present invention can be used in place of the moisture-proof properties of conventional crystalline synthetic resin films, and can be used for long-term moisture-proof retention by directly packaging drugs, foods, etc. An object of the present invention is to provide a highly moisture-proof packaging material based on paper that can be reused through a recycling system.

[0007]

[Means for Solving the Problems] The method for producing a moisture-proof packaging material using paper as a base material according to the present invention involves coating a paper surface with an aqueous polymer dispersion having a minimum film-forming temperature of 1°C or higher to form a first layer. A moisture-proof coating consisting of the first and second layers is formed by coating the first layer with an aqueous dispersion of wax and polymer and drying under heat to form the second layer. It is characterized by forming a composite layer of color on paper.

[0008]

Effects of the Invention According to the present invention, it is possible to obtain a moisture-proof packaging material based on paper having high moisture resistance, which has been considered difficult in the past. This makes it possible to switch to moisture-proof packaging materials.

That is, in the moisture-proof packaging material according to the present invention,
Moisture permeability of 10 g/m is lower than that of crystalline synthetic resin film alone, which is used as a general moisture-proof packaging material for foods, etc.
It is possible to obtain moisture resistance with low moisture permeability of 2.24 hours or less. In particular, it is possible to obtain high moisture resistance with a moisture permeability of 3 g/m 2 ·24 hours or less, that is, higher moisture resistance than a crystalline synthetic resin film with low moisture permeability. Therefore, medicines, foods, etc. can be directly packaged and stored for a long period of time in a highly moisture-proof state. Furthermore, after use, the paper can be easily recovered in the waste paper recovery process, thereby saving paper resources.

[Detailed Description of the Invention] Specifically, the moisture-proof packaging material based on paper according to the present invention is produced by first forming a moisture-permeable polymer film on the paper surface, and then applying a wax-containing film (wax-containing film) thereon. This is a packaging material having an integral coating of both coatings, that is, a composite coating, obtained by forming a moisture-proof coating consisting of a polymer and a moisture-proof coating. The manufacturing method for the moisture-proof packaging material is to coat paper with a polymer emulsion with a minimum film-forming temperature of 1°C or higher.
Dry to form a moisture permeable polymer coating. Next, an emulsion of wax and a polymer is applied to the moisture-permeable polymer film and dried by heating to form a wax-containing film.

[0011] Regarding the composite film according to the present invention, the polymer film and wax-containing film forming the composite film,
The following matters were discovered by the present inventor. (a) The moisture resistance of the composite film is significantly higher than that of a laminated layer of a moisture-permeable polymer film and a wax-containing film formed separately. Furthermore, even if the thickness of the laminated layer is larger than that of the composite coating, its moisture resistance is significantly lower than that of the composite coating. (b) Even if only a moisture-permeable polymer coating is laminated and its thickness is greater than that of a composite coating, its moisture resistance is significantly lower than that of the composite coating. (c) By changing the type of polymer and/or the composition ratio of wax and polymer, a wax-containing film with low moisture permeability can be formed, and even if the film is thicker than the composite film, its moisture-proofing properties will still be higher than that of the composite film. considerably lower. (d) Even if a low moisture permeability polymer coating is formed by a method other than the present invention and a wax-containing coating is formed thereon from an emulsion, the moisture resistance of the coating is considerably low. (e) The polymer film in the composite film had changed to have low moisture permeability. That is, the polymer film changed from moisture permeability to low moisture permeability during the process of forming the composite film. From these, the composite film according to the present invention has a moisture-proofing function that is not found in conventional paper moisture-proofing wax-containing coatings.
It can be assumed that a moisture-proofing function different from the conventional one is generated, or that both are generated together.

<Base material> The paper used in the present invention serves as a base material for a moisture-proof packaging material. There are no particular restrictions on the paper itself, and any paper that can be used for packaging can be used regardless of its type or manufacturing method. Preferred examples of paper used in the present invention include writing paper, printing paper, packaging paper, and paperboard. However, in the case of paper with low smoothness, "uneven coating" tends to occur with ordinary coating methods. Therefore, the smoothness (J
Papers with a high smoothness (according to IS P8119) are preferred, preferably with a smoothness of 50 seconds or more, particularly preferably 100 seconds or more. If the paper is not sized or has a weak sizing, the rate of water penetration from the coated film into the paper will be too fast, again resulting in ``uneven coating'' and ``coating streaks.'' Cheap. Therefore, it is preferable to use paper whose sizing degree (according to JIS P8122) is preferably 1 second or more, particularly preferably 3 seconds or more.

[0013] Since paper is made of cellulose fibers,
It swells and contracts during the process of applying the aqueous dispersion and subsequent drying. Therefore, when the first and second layers are formed, their layer coatings also follow the swelling and contraction of the paper, and if the layer coatings cannot follow the swelling and shrinkage, "streaks" will occur in the coating. Therefore, it is preferable that the behavior of the paper from swelling to shrinkage is not large, that is, the elongation under water is small. The water immersion elongation is preferably 4% or less, particularly preferably 3% or less in terms of "horizontal" elongation.

<First Layer> In the present invention, first, an aqueous polymer dispersion having a minimum film-forming temperature of 1° C. or higher is applied to a paper surface and dried to form a first layer on the paper surface. The first layer is a moisture permeable polymer coating. That is, a coating film is formed by coating an aqueous polymer dispersion on a paper surface (paper fiber collection surface), and the coating film is dried on the paper fiber collection surface to form a film. Moreover, since the polymer coating is made of a polymer that is soft enough to provide the dispersion with film-forming properties such as a minimum film-forming temperature of 1°C or higher, a composite coating with appropriate moisture permeability, that is, high moisture resistance, is formed. It has moisture permeability suitable for.

According to the present invention, the moisture permeability of the first layer may be that of a polymer coating formed from an aqueous polymer dispersion having a minimum film forming temperature of 1° C. or higher. However, the moisture-proof packaging material according to the present invention that enjoys the effects of the present invention the most is 3 g/
It has a low moisture permeability of less than m2 ・24h.
The moisture permeability of the first layer is preferably 500 to 7000 g/
m2・24h, particularly preferably 1000 to 5000
g/m2.24h.

[0016] These moisture permeable polymer coatings have a water vapor permeability of 1
It can be obtained by a method such as selecting a polymer that provides an appropriate minimum film-forming temperature to an aqueous polymer dispersion in a temperature range of .degree. C. or higher. The selection of the polymer is made based on, for example, the type, molecular weight, glass transition point, or copolymerization ratio. For example, a polymer film having a water vapor permeability of 500 to 7000 g/m 2 ·24 h can be formed from an aqueous polymer dispersion having a minimum film forming temperature of 10 to 35° C., such as an emulsion of a styrene-butadiene copolymer. The polymer film of the first layer is formed from an aqueous polymer dispersion, so it is formed not only on the paper but also within the paper by fixing to the paper fibers.

The "aqueous polymer dispersion" is one in which the polymer is stably dispersed in water in the form of fine particles. Moreover, 1℃
It has film forming properties at the above minimum film forming temperature.
A typical example of an aqueous polymer dispersion is a polymer emulsion. The term "emulsion" is used in a narrow or broad sense. However, in the description of the invention,
The term "polymer emulsion" is used to refer to fine particles of a polymer stably dispersed in water using an emulsifier. Furthermore, the term "emulsion of a polymer and wax" is used to mean a fine particle of a polymer and wax that is stably dispersed in water using an emulsifier. Furthermore, the term "emulsion" is an abbreviation for a polymer emulsion or a polymer and wax emulsion. Furthermore, what is customarily called a "polymer emulsion" or simply "emulsion" is a synthetic resin that is stably dispersed in water using an emulsifier in the form of fine particles.
It is included in the polymer emulsion that can be used in the present invention. Furthermore, fine particles of rubber that are stably dispersed in water using an emulsifier are sometimes conventionally referred to as latex. However, since rubber is also a polymer, what is conventionally referred to as latex is also included in the polymer emulsions that can be used in the present invention.

There are no restrictions on the production of emulsions, and emulsions can be obtained directly from polymerization, such as emulsion polymerization, or by stably dispersing pre-polymerized polymers into water in the form of fine particles with an emulsifier. It may be any emulsion. Further, the emulsion may be prepared by mixing a plurality of emulsions. Note that the emulsion contains various components other than the emulsifier, such as a water-soluble polymerization initiator and a dispersion stabilizer, but there are no particular restrictions as far as the emulsion used for the first layer is concerned. Note that "minimum film forming temperature of 1° C. or higher" means that the aqueous polymer dispersion has a film forming ability at a temperature of 1° C. or higher. It should be noted that if the temperature is less than 1°C, the moisture proofing properties of the composite film according to the present invention will be low. If the minimum film-forming temperature of the aqueous polymer dispersion becomes too high, the polymer coating of the first layer will become too hard. Therefore, the upper limit of the minimum film forming temperature is preferably 60°C.

The polymer used is one that can be dispersed in water in the form of fine particles and has the property of imparting film-forming properties to the aqueous dispersion with a minimum film-forming temperature of 1° C. or higher. Furthermore, the polymer is preferably one that has adhesive properties to the paper fibers to fix the polymer film of the first layer to the paper fibers. It is preferable that the tension is small. Furthermore, it is preferable to use a material that has adhesive properties with the second layer coating. The "polymer" may be a homopolymer or a copolymer, or may contain both. Note that polymers are sometimes conventionally classified into synthetic resins and elastomers (those with high elongation and elasticity, such as rubber). Furthermore, thermoplastic resins with high elongation and elasticity are separated from elastomers and called thermoplastic elastomers, and are sometimes conventionally classified into synthetic resins, thermoplastic elastomers, and rubber. However, both are included in the "polymer" in the present invention. The same type of polymers may be used alone, or different types of polymers may be used in combination.

Specific examples of polymers include the following. (A) vinyl acetate polymer, vinyl acetate-methyl acrylate copolymer, vinyl acetate-ethyl acrylate copolymer,
Vinyl acetate-based polymers such as vinyl acetate-butyl acrylate copolymer, vinyl acetate-2-ethylhexyl acrylate copolymer, vinyl acetate-dibutyl maleate copolymer, vinyl acetate-ethylene copolymer, (B ) Methyl acrylate polymer, ethyl acrylate polymer, butyl acrylate polymer, 2-ethylhexyl acrylate polymer,
Acrylic acid ester polymers such as butyl acrylate-methyl methacrylate copolymer, butyl-styrene acrylate copolymer, tyrene-acrylic acid-2-ethylhexyl copolymer, (C) styrene-butadiene copolymer, Butadiene polymers such as nitrile-butadiene copolymer, vinylpyridine-styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, (D) isoprene polymer such as isoprene polymer, (E) styrene polymer Styrene polymers such as (F) ethylene polymers, ethylene-vinyl acetate copolymers, etc. Note that when using a polymer with poor polarity such as an ethylene polymer, it is desirable to use it together with a polymer or copolymer with high polarity.

There are no restrictions on the means for applying and drying the aqueous polymer dispersion. Drying may be either natural drying or artificial drying, but industrially it is preferable to use artificial drying by heating with a drying device. The heating drying temperature can be changed depending on the drying time. Generally, 40~
The temperature is 280°C, preferably 80-200°C. If the coating amount is too small, the coating will become too thin and the moisture-proofing ability of the composite layer will be insufficient. Furthermore, if the amount is too large, the thickness of the coating tends to be non-uniform. Therefore, the coating amount is preferably 10 to 30 g (in terms of solid content in the aqueous dispersion)/m2. The thickness of the first layer is between 5 and 40 micrometers, preferably between 10 and 30 micrometers.

<Second layer> In the present invention, the second layer is formed by applying an aqueous dispersion of wax and polymer to the polymer film of the first layer and drying it under heat. Form. The second layer is a wax-containing coating consisting of wax and polymer. By forming the second layer, an integral moisture-proof composite layer (composite coating) consisting of the first and second layers is formed. That is, when an aqueous dispersion of wax and polymer is applied onto the first layer, the underlying polymer coating (first layer) is moisture permeable and therefore contains the aqueous dispersion. In addition, the aqueous dispersion permeates through the polymer coating and spreads to the back side of the paper (the paper surface opposite to the paper surface where the first and second layers are located), and also spreads between the first and second layers. It can also spread between Therefore, the moisture permeable polymer coating of the first layer becomes loaded with the components of the second layer.

[0023] When the coating film of the first layer is heated for drying, the second layer is also heated. Therefore, the polymer coating of the first layer containing wax or the like can be changed by heating. In addition, heating can cause various effects between the coating film of the first layer and the polymer coating of the first layer, such as fusion of both coatings and migration of coating film components to the first layer. It is possible to bring about the following effects. To this end, by heating and drying the coated film to form a second layer, it is possible to add a moisture-proofing function that is not found in conventional paper moisture-proofing wax-containing coatings, and/or to create a high moisture-proofing layer that has a moisture-proofing function that is different from the conventional moisture-proofing function. A composite layer (composite film) can be produced. The heating temperature can be changed depending on the length of the heating time, but for example, 40 to 28
The temperature may be 0°C.

[0024] The effect of the present invention, that is, the moisture permeability is 3
g/m2.24h The heating temperature that produces the following extremely high moisture resistance is preferably 80 to 200°C. Typical examples of “aqueous dispersions of wax and polymer” are:
It is an emulsion of wax and polymer. The emulsion is prepared by a conventional method. The emulsion may be prepared by mixing a wax, a polymer, and each emulsion. Note that there is no restriction on the minimum film-forming temperature for the aqueous dispersion of the second layer. However, in order to make the wax-containing film of the second layer a strong continuous film with a uniform surface, it is preferable to have a low minimum film-forming temperature, that is, one in which components that provide a low minimum film-forming temperature are dispersed. .

The range of the weight ratio of wax to polymer (wax/polymer) in the aqueous dispersion is preferably 10/90.
~50/50, particularly preferably 15/85 to 25/75
, is. That is, the wax-containing coating of the second layer is
When the wax and polymer are contained in such a ratio, the moisture resistance of the film itself can be increased. Moreover, the moisture permeability of the first layer is 500-7000g/m2・24h,
Preferably 1000-5000g/m2・24h,
and the weight ratio of wax to polymer in the second layer is
With such a ratio, the moisture resistance of the composite layer can be significantly increased (for example, moisture permeability of 3 g/m 2 ·24 h or less).

[0026] When a food packaging bag is made from the moisture-proof packaging material of the present invention, the second layer becomes the surface that comes into contact with the food. Therefore, in that case, an aqueous dispersion, such as an emulsion, to which an emulsifier (surfactant) is added as permitted by the Food Sanitation Law is used. Substances that are not permitted to be used as food additives under the Food Sanitation Act, such as the antioxidant BHT, cannot be added.

Surfactants and others that are permitted as food additives include propylene glycol fatty acid esters, glycerin fatty acid esters, sorbitan fatty acid esters, sugar fatty acid esters, and lecithin. The emulsifier added to the emulsion may be in a conventional amount. For example, it is 0.5 to 2.5%. There are no restrictions on the means of applying and drying the "aqueous dispersion." The coating amount of the "aqueous dispersion" is preferably 3 to 20 g (solid equivalent of the aqueous dispersion)/m2, particularly preferably 5 to 15 g/m2.
g/m2. If the coating amount is too small, the high moisture resistance of the composite layer tends to be insufficient. If the amount is too large, the coating on the first layer will become too thick, resulting in poor crease performance.

There are no particular restrictions on the wax used in the present invention. Typical examples include those derived from natural animals and plants or petroleum. That is, animal waxes derived from natural animals and plants (typically beeswax) or vegetable waxes (typically carnauba wax) can be used. Furthermore, as those derived from petroleum, paraffin wax (crystalline wax), intermediate wax (motor oil wax), microcrystalline wax (microcrystalline wax) and polyethylene wax can be used. Among these, it is preferable to use paraffin wax. Further, the properties of wax can be expressed by melting point, penetration, uniformity, cohesiveness, shrinkage, water resistance, coagulation, etc., but the wax used in the present invention is solid at room temperature and transparent. Preferably one with low humidity. For example, it is suitable to use one having a melting point of 120°C or lower. The waxes may be of the same type or a combination of different types. Further, even if they are of the same type, those having different properties such as melting point may be used in combination.

The polymer used in the second layer may be a homopolymer or a copolymer, or may contain both. It includes all those conventionally classified as synthetic resins and elastomers, or those conventionally classified as synthetic resins, thermoplastic elastomers, and rubbers. However, it is necessary that there be a substance that can coexist with wax to form an aqueous dispersion and that can form a film by mixing with wax. A film in which wax and polymer are uniformly mixed generally has low permeability and can form a moisture-proof wax film. In particular, it is preferable that the weight ratio (wax/polymer) to wax is in the range of 10/90 to 50/50, so that the wax can be uniformly mixed to form a film and improve the moisture resistance of the film. Moreover, it is preferable that the polymer itself is a thermoadhesive polymer or contains a thermoadhesive polymer. The use of a thermoadhesive polymer provides the second layer with excellent heat-sealing properties and hot-tack properties, making it possible to make the packaging material of the present invention excellent in bag-making suitability. Here, the thermal adhesive polymer is a polymer that has adhesive properties under heating.

[0030] As the thermoadhesive polymer, for example, thermoplastic resins (including thermoplastic elastomers), rubber, etc., which have thermoadhesive properties and can be mixed with wax, can be used. The reason why the term "thermoplastic elastomer" is included here is that a thermoplastic resin having elasticity is sometimes called a thermoplastic elastomer, which is a different name from the thermoplastic resin. The polymers (including thermoadhesive polymers) may be of the same or different types.

Specific examples of polymers include the following. (A) vinyl acetate polymer, vinyl acetate-methyl acrylate copolymer, vinyl acetate-ethyl acrylate copolymer,
Vinyl acetate-based polymers such as vinyl acetate-butyl acrylate copolymer, vinyl acetate-2-ethylhexyl acrylate copolymer, vinyl acetate-dibutyl maleate copolymer, vinyl acetate-ethylene copolymer, (B ) Methyl acrylate polymer, ethyl acrylate polymer, butyl acrylate polymer, 2-ethylhexyl acrylate polymer,
Styrene-acrylic acid-2-ethylhexyl copolymer,
Acrylic acid ester polymers such as butyl acrylate-methyl methacrylate copolymer, butyl acrylate-styrene copolymer, (C) styrene-butadiene copolymer,
Butadiene polymers such as nitrile-butadiene copolymer, vinylpyridine-styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, and ethylene polymers such as (D) ethylene-vinyl acetate copolymer. Preferred are vinyl acetate polymers and acrylic ester polymers, such as styrene-2-ethylhexyl acrylate copolymer. The second layer polymer can also be of the same type as the first layer polymer. The thickness of the second layer can vary arbitrarily, but is generally preferably between 3 and 20 micrometers, particularly preferably between 5 and 15 micrometers.

<Manufacturing Conditions> In the method for manufacturing a moisture-proof packaging material according to the present invention, a highly moisture-proof composite layer can be obtained even if the conditions are changed as appropriate. For example, changing the ratio of the thickness of the first and second layers, changing the amount of wax in the second layer depending on the water vapor permeability of the first layer, or changing the minimum formulation of the aqueous polymer dispersion of the first layer. For example, the amount of wax in the second layer may be changed depending on the film temperature, or the combination of polymers in the first and second layers may be changed. Further, there are no restrictions on the production of a moisture-proof packaging bag from the moisture-proof packaging material according to the present invention, or on the size and form of the packaging bag.

[0033]

【Example】

Example 1 Minimum film-forming temperature of 30 on high-quality paper with a basis weight of 46.5 g/m2
~35℃ SBR emulsion (trade name, Crossren S
K-74 (manufactured by Takeda Pharmaceutical Co., Ltd.) with a Meyer bar 2
It was coated at a weight of 5 g/m2 and dried at 105°C for 2 minutes to form an undercoat layer (first layer). The moisture permeability of the undercoat layer is 3300g/m2・24h
Met. The moisture permeability was measured according to JIS Z0208 (moisture permeability test method for moisture-proof packaging materials (cup method)) at a temperature of 40° C. and a relative humidity of 90%. Next, 100 parts by weight of paraffin wax (not containing antioxidant) with a melting point of 70°C emulsified with sorbitan fatty acid ester and styrene-2-ethylhexyl acrylate (glass transition point -10°C) were used as main components to minimize film formation. Soap-free emulsion at temperature below 0℃ (product name: AE-933, JS
Co., Ltd.) on the undercoat layer using a Meyer bar at a coating density of 25 g/m2, and dried at 105°C for 2 minutes to form an overcoat layer (second layer). was formed. The moisture permeability of the obtained packaging material is determined by JIS
Measured according to Z0208. Measurement was carried out at a temperature of 40℃
The test was conducted at a relative humidity of 90%. Moisture permeability is 2.1g
/m2・24h. In addition, the heat sealing strength was sufficient during bag making.

Example 2 An emulsion (trade name, RIKABOND ES- J-806 (manufactured by Chuo Rika Kogyo Co., Ltd.) was coated with a Meyer bar to a coating density of 32 g/m2, and 105
C. for 2 minutes to form an undercoat layer (first layer). The moisture permeability of the undercoat layer is 1700g/m
It was 2.24 hours. Next, an overcoat layer (second layer) was formed in the same manner as in Example 1, and the moisture permeability was measured in the same manner. The moisture permeability of the obtained packaging material was 1.5g/
m2・24h.

Example 3 The same undercoat layer (first layer) was formed on high-quality paper (same as in Example 1) by the same method as in Example 1, and on top of that, a layer of melting point 70 emulsified with sorbitan fatty acid ester was applied. Microcrystalline wax (
A mixture of 100 parts by weight of an emulsion (one that does not contain antioxidants) and 400 parts by weight of a soap-free SBR emulsion (trade name, Crossren SK-72, manufactured by Takeda Pharmaceutical Co., Ltd.) with a minimum film forming temperature of 0°C. 1 with Meyer bar
It was coated at a weight of 6 g/m2 and dried at 105°C for 2 minutes to form an overcoat layer (second layer). The moisture permeability of the obtained packaging material was measured in the same manner as in Example 1, and was found to be 1.4 g/m 2 ·24 h. In addition, the heat sealability was also good during bag making.

Comparative Example 1 SBR with minimum film forming temperature of 0°C on high quality paper (same as Example 1)
Emulsion (trade name, Crossren SK-73, manufactured by Takeda Pharmaceutical Company Limited) was coated with a Meyer bar, and heated at 105°C.
It was dried for 2 minutes to form an undercoat layer. The moisture permeability of the undercoat layer was 440 g/m 2 ·24 h. Thereon, an overcoat layer was formed in the same manner as in Example 1. The moisture permeability of the obtained packaging material was measured in the same manner as in Example 1, and was found to be 220 g/m 2 ·24 h.

Comparative Example 2 16 g of the same overcoat layer (second layer) as in Example 3 was applied directly to the high-quality paper used in Example 1 without providing an undercoat layer (first layer) on the high-quality paper. /m2. The moisture permeability of the obtained packaging material was 28.9 g/m2
・It was 24 hours. Further, when the overcoat layer (second layer) was formed by coating at 22 g/m2, the moisture permeability was 21.6 g/m2·24 h.

Comparative Example 3 Emulsion (trade name: AE-933, manufactured by JSR Corporation) used for the overcoat layer (second layer) in Example 1
A soap-free acrylic emulsion (trade name, AE-932, JSR) with a minimum film-forming temperature of 40℃
The procedure was the same as in Example 1, except that the same procedure was used as in Example 1. The moisture permeability of the obtained packaging material is 1330g/m2 ・24h
Met.

Comparative Example 4 Emulsion (trade name: AE-933, manufactured by JSR Corporation) used for the overcoat layer (second layer) in Example 1
A soap-free acrylic emulsion (product name, Ricabond ES-J-) with a minimum film-forming temperature of 10℃
The procedure was the same as in Example 1 except that 806 (manufactured by Chuo Rika Kogyo Co., Ltd.) was used. The moisture permeability of the obtained packaging material is 260
g/m2・24h.

Comparative Example 5 Commercially available double-sided coated art paper (basis weight 127.9 g/m2
) was coated with the overcoat layer of Example 3 at 8 g/m2, and after drying at 105°C for 2 minutes and moisture permeable, the result was 13
It was 2.5g/m2・24h. In addition, the moisture permeability of double-sided coated art paper before providing an overcoat layer is 2.
It was 650g/m2・24h. Table 1 below shows
The results obtained in the above examples and comparative examples are tabulated.

[0041]

[Table 1]

Claims (4)

[Claims] Claim 1: A first layer is formed by applying an aqueous polymer dispersion having a minimum film forming temperature of 1° C. or higher to a paper surface, and an aqueous dispersion of wax and polymer is applied to the first layer. A moisture-proof packaging material based on paper, in which a moisture-proof composite layer consisting of the first and second layers is formed on paper by processing and drying under heat to form a second layer. Manufacturing method. 2. The first layer has a moisture permeability of 500 to 7000 g.
2. The method for producing a moisture-proof packaging material according to claim 1, wherein the second layer is formed on the second layer. 3. The first layer has a moisture permeability of 500 to 7000 g.
/m2 ・24h and a weight ratio of wax to polymer (wax/polymer) of 10/9.
2. The method for producing a moisture-proof packaging material according to claim 1, wherein the second layer is formed from an aqueous dispersion of the wax and polymer in a ratio of 0 to 50/50. 4. The moisture-proofing device according to claim 1, wherein the polymer of the aqueous dispersion of wax and polymer is a thermoadhesive polymer or a polymer containing a thermoadhesive polymer. Method of manufacturing packaging materials.