JP4757363B2 - Foam container and food packaging - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is excellent in heat insulation, heat resistance, and microwave resistance, can be heated in a state where the contents are stored and packaged, and also has excellent gas barrier properties, and deteriorates when it comes into contact with the outside air. The present invention relates to a foam container that can store easily easy contents for a long time, and a food packaging material provided with the foam container.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, foam containers have excellent heat insulation properties, and thus are frequently used for storing / packaging of refrigerated or frozen contents, storing / packaging of heated contents, and the like.
[0003]
For example, as an example of storage / packaging of refrigerated or frozen contents, specifically, processed meat products and processed fishery products are very susceptible to spoilage and deterioration, but these processed products are refrigerated or frozen. If it is stored and packaged in the foam container, it can be kept refrigerated or frozen for a long time.
[0004]
In addition, as an example of storage and packaging of heated contents, if heated food such as ramen, udon, curry, cooked rice, stew, etc. is stored and packaged in a foam container, the heated state can be kept for a long time. Can be maintained. Furthermore, the heat insulating property of the foam container makes it possible to hold a container in which the heated food is stored and packaged in a hand without the user almost feeling high temperature.
[0005]
Since the foam container is widely used for the above-described applications requiring heat insulation, the demand for the foam container is very large. Further, the foam container is provided with gas barrier properties. It is preferable. This is because the contents stored and packaged in the foam container, in particular, food can be effectively prevented from being spoiled or deteriorated, and the contents can be stored for a longer period of time.
[0006]
Specifically, the contents stored in the foam container, particularly foods, may deteriorate due to oxidation when exposed to the outside air, or aerobic bacteria, molds, etc. may grow and decay. Moreover, there is a possibility that the volatile matter such as moisture contained in the contents may be deteriorated by evaporating and diffusing. Therefore, if the gas barrier property is imparted to the foam container, the above-described problems can be effectively suppressed, so that the contents can be stored for a longer period.
[0007]
Examples of a method for imparting gas barrier properties to the foam container include a method of laminating a resin layer (gas barrier layer) having gas barrier properties on the foam container. As a method for laminating the gas barrier layer on the foam container, for example, a non-stretched co-extruded gas barrier resin layer is bonded to a foam sheet to form a laminated foam sheet, and vacuum molding is performed after the lamination. And a method of forming a foam sheet by vacuum molding or the like, and then laminating the gas barrier resin by spin coating, dipping coating, spray coating, or the like. .
[0008]
As the resin used for the gas barrier layer, an ethylene-vinyl alcohol copolymer and a polyvinylidene chloride resin are generally used. Among these, the polyvinylidene chloride-based resin has characteristics such as excellent gas barrier properties as compared with other resins and excellent chemical resistance. Further, for example, by making this polyvinylidene chloride resin into an emulsion, it becomes easy to coat the surface of the foam container as described above.
[0009]
[Problems to be solved by the invention]
However, the conventional gas barrier layer containing the above-mentioned polyvinylidene chloride resin needs to have a relatively large thickness in order to exhibit effective gas barrier properties. If the thickness of the layer is large, the thickness and amount of the layer of the different material with respect to the resin foam as the base material will increase, and the moldability after being laminated on the foam sheet will be reduced. Invite problems.
[0010]
In the case where the gas barrier layer is laminated after the foam container is first molded, there is no problem in moldability, but the amount of the gas barrier layer which is a different material increases. Since it is difficult to separate the gas barrier layer from the foam container body as a base material, there is a problem that it is difficult to recycle.
[0011]
Furthermore, incineration can be considered when recycling is difficult, but when the gas barrier layer is a polyvinylidene chloride-based resin, it contains an environmentally damaging substance such as chlorine. Therefore, if it is easily incinerated, there is a possibility of producing an organic chlorine compound and polluting the environment. Therefore, if there are many different materials, the incineration suitability will be lowered as a result.
[0012]
Therefore, conventionally, there has been a demand for a foam container that is excellent in moldability, recyclability, and incineration, and that can exhibit high gas barrier properties.
[0013]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the inventors of the present invention have a much thinner film thickness than conventional gas barrier layers if a gas barrier layer made of a resin composition having an inorganic layered compound is laminated on a foam container. Discovered that it can exhibit excellent gas barrier properties, does not contain substances that burden the environment, and can reduce the amount of gas barrier layers, which are dissimilar materials, to improve recyclability and incineration. It came to do.
[0014]
That is, the foam container of the present invention is characterized in that a gas barrier layer made of a resin composition having an inorganic layered compound is laminated on a resin foam layer in order to solve the above-described problems.
[0015]
According to the above configuration, the foam container according to the present invention is excellent in a very thin film thickness as compared with a polyvinylidene chloride resin and an ethylene-vinyl alcohol copolymer conventionally used as a gas barrier layer. It has a gas barrier layer that can exhibit its gas barrier properties. Therefore, even if the foam sheet is molded after the gas barrier layer is formed first, a high-quality foam container can be obtained without lowering the moldability.
[0016]
In addition, when the gas barrier layer is laminated after molding the foam container, the gas barrier layer can be made very thin, so that the gas barrier layer as a different material existing in the foam container can be reduced, and recyclability and Incineration suitability can be improved.
[0017]
The resin foam is molded in advance as a container, and the gas barrier layer is laminated by coating at least one of the inner surface and the outer surface of the container with a coating liquid composed of a resin composition having an inorganic layered compound. It is preferred that Moreover, it is preferable that the said container is shape | molded by the vacuum forming method or the pneumatic forming method.
[0018]
According to the above configuration, since the gas barrier layer is laminated after the container is molded in advance, the molding of the container and the lamination of the gas barrier layer can be performed with a high degree of freedom. In addition, it is preferable that the container is formed by vacuum forming or pressure forming because a thin container can be formed well.
[0019]
Instead of molding the container first as described above, the gas barrier layer is first laminated on the foam to form a laminated foam sheet, and this laminated foam sheet is molded by vacuum molding or pressure molding. May be.
[0020]
Since the gas barrier layer can have a very thin film thickness, a foam container molded with high accuracy can be obtained without hindering moldability even if it is later molded as a laminated foam sheet.
[0021]
The oxygen permeability of the foam container according to the present invention is 1 mL / m. ² ・ It is preferable that it is below day ・ atm, 0.1 mL / m ² ・ Day ・ Atm or less is more preferable, 0.05 mL / m ² -It is more preferable that it is below day-atm. When the oxygen permeability is within this range, the deterioration of the contents stored in the frozen state can be suppressed and retained for a longer period of time.
[0022]
In the foam container according to the present invention, the inorganic layered compound is preferably swollen and cleaved in a dispersion medium, and the gas barrier layer is obtained by subjecting a mixed liquid of a resin composition having an inorganic layered compound to high-pressure dispersion treatment. It is preferable that The pressure condition for the high-pressure dispersion treatment is 100 kgf / cm. ² Preferably, it is 500 kgf / cm. ² More preferably, it is 1000 kgf / cm. ² The above is particularly preferable.
[0023]
Moreover, it is preferable that the aspect-ratio of an inorganic layered compound exists in the range of 50-5000, More preferably, it exists in the range of 200-3000.
[0024]
The resin composition contains a high hydrogen bonding resin, and the weight ratio of the inorganic layered compound and the high hydrogen bonding resin is preferably (1/100) to (100/1), more preferably (1/20) to It is within the range of (10/1). In this case, the high hydrogen bond resin preferably has a hydrogen bond group or ionic group mol% per unit weight of the resin of 30% or more and 50% or less. A modified product, a polysaccharide, or an ethylene-vinyl alcohol copolymer and a modified product thereof are preferable.
[0025]
By providing each of these configurations, it is possible to further improve the gas barrier properties of the container, and to further effectively suppress the deterioration of the contents.
[0026]
The food packaging material according to the present invention includes a foam container having the above-described configuration. Therefore, it is possible to store and wrap heated food such as ramen, yakisoba, spaghetti, cooked rice, curry, stew, etc. in a cookable state, and the insulation of the foam container makes the container a tableware. Can also be used. In addition, by storing and wrapping fresh food such as processed meat products and processed fishery products in a refrigerated or frozen state, they can be kept in a refrigerated or frozen state for a long time, and the contents can be kept for a long time due to gas barrier properties It can also be possible to save.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
The embodiment of the present invention will be described with reference to FIGS. 1 to 7 as follows.
The foam container according to the present invention is formed by laminating a gas barrier layer having an inorganic layered compound on a foam container.
[0028]
The inorganic layered compound used in the gas barrier layer is an inorganic compound in which unit crystal layers are stacked on each other to have a layered structure. In the cleaved state, the particle size is 5 μm or less, the aspect ratio is about the gas barrier property. It is not particularly limited as long as it is in the range of 50 to 5000, more preferably the aspect ratio is in the range of 200 to 3000.
[0029]
If the aspect ratio is less than 50, the gas barrier property is not sufficient, and if it is more than 5000, it is technically difficult and economically expensive. Further, if the particle size is 3 μm or less, the transparency becomes better, and if the particle size is 1 μm or less, it is more preferable for applications in which transparency is important.
[0030]
Specific examples of the inorganic layered compound include graphite, phosphate derivative compounds (such as zirconium phosphate compounds), chalcogenides, and clay minerals. Here, the “chalcogen compound” is a dichalcogenide of group IV (Ti, Zr, Hf), group V (V, Nb, Ta) and group VI (Mo, W), which has the formula MX ₂ (M represents the above element, and X represents chalcogen (S, Se, Te).)
[0031]
The particle size of the inorganic layered compound refers to the particle size obtained by the diffraction / scattering method in the dispersion medium. Although it is extremely difficult to measure the true particle size in the gas barrier layer, when it is sufficiently swollen and cleaved with the same type of dispersion medium as used in the diffraction / scattering method, and combined with the resin used in the gas barrier layer, It can be considered that the particle size of the cleaved unit crystal layer 31 in the resin 32 in the gas barrier layer 3 shown in FIG. 1 corresponds to the particle size of the cleaved inorganic layered compound in the dispersion medium.
[0032]
[Method for obtaining average particle diameter]
The average particle diameter of the particles in the liquid can be determined by a diffraction / scattering method, a dynamic light scattering method, a method of changing electrical resistance, a method of image processing after microscopic photography in liquid, and the like.
[0033]
When the resin and particles coexist in the dynamic light scattering method, it is difficult to evaluate because the apparent liquid viscosity changes from that of a pure dispersion medium, and the electric resistance change method has a limitation on the electrolyte concentration of the liquid. The method using image processing after medium microscope photography has a problem of resolution and is difficult to use.
[0034]
When the diffraction / scattering method is used, a resin solution, for example, an aqueous resin liquid, has substantially little scattering (that is, transparent), and when particle-derived scattering is dominant, the particle size distribution of the particles regardless of the presence or absence of the resin. It is preferable because only information can be obtained.
[0035]
[Average particle size measurement by diffraction / scattering method]
The particle size distribution and average particle size measurement by the diffraction / scattering method is based on the diffraction / scattering pattern obtained when light is passed through a dispersion in which an inorganic layered compound that has been swollen and cleaved is dispersed in an aqueous dispersion medium. This is done by calculating the most consistent particle size distribution using the scattering theory.
[0036]
Commercially available devices include particle size measuring devices by laser diffraction / light scattering (LS230, LS200, LS100, manufactured by Coulter), laser diffraction particle size distribution measuring devices (SALD2000, SALD2000A, SALD3000, manufactured by Shimadzu Corporation), laser diffraction / Examples thereof include a scattering type particle size distribution measuring device (LA910, LA700, LA500, manufactured by Horiba, Ltd., Microtrac SPA, Microtrac FRA, Nikkiso).
[0037]
[Aspect ratio measurement method]
An aspect ratio (Z) is a ratio calculated | required from the relationship of Z = L / a. Here, L is the particle size (volume-based median diameter) of the inorganic layered compound obtained by the particle size measurement method by the diffraction / scattering method described above in the dispersion, and a is a cleaved unit shown in FIG. This is the unit thickness of the crystal layer 31. This “unit thickness a” is a value determined on the basis of the result of independent measurement of the thickness of the inorganic layered compound by a powder X-ray diffraction method to be described later.
[0038]
More specifically, as shown schematically in the graph of FIG. 2 in which the horizontal axis represents 2θ and the vertical axis represents the intensity of the X-ray diffraction peak, it corresponds to the lowest angled peak among the observed diffraction peaks. The interval determined based on the Bragg equation (nλ = 2Dsinθ, n = 1, 2, 3,...) From the angle θ to be measured is defined as “unit thickness a” (for details of the powder X-ray diffraction method) (For example, see Jiro Shiokawa's “Guide to Instrumental Analysis (a)” p. 69 (1985) published by Kagaku Dojinsha).
[0039]
When the resin composition corresponding to the gas barrier layer 3 obtained by removing the dispersion medium from the dispersion is subjected to powder X-ray diffraction, the interplanar spacing of each inorganic layered compound dispersed in the resin composition is usually shown in FIG. 1 can be obtained as the surface distance d shown in FIG.
[0040]
More specifically, as schematically shown in the graph of FIG. 3 in which the horizontal axis represents 2θ and the vertical axis represents the intensity of the X-ray diffraction peak, the diffraction peak position corresponding to the “unit thickness a” described above is used. Of the diffraction peaks observed on the low angle (larger interval) side, the interval corresponding to the peak on the lowest angle side is defined as “surface interval d” (a <d).
[0041]
As schematically shown in the graph of FIG. 4, in the case where it is difficult to detect the peak corresponding to the “surface distance d” overlapping the halo (or background), the baseline on the lower angle side than 2θd The area excluding “” is a peak corresponding to “surface distance d”. Here, “θd” is a diffraction angle corresponding to “(unit thickness a) + (width of single resin chain)” (For details of the calculation method of the interplanar spacing d, for example, Shuichi Iwao et al. Ed., “Encyclopedia of Clay”, 35 pages and 271 pages, 1985, Asakura Shoten Co., Ltd.).
[0042]
Usually, the difference between the above-mentioned surface distance d and “unit thickness a”, that is, the value of k = (da) (when converted to “length”) is one resin constituting the resin composition. It is equal to or greater than the chain width [k = (da) ≧ width of single resin chain]. Such “resin single chain width” can be determined by simulation calculation or the like (for example, see “Introduction to Polymer Chemistry”, pages 103 to 110, 1981, Chemical Dojin). In some cases, it is 4-5 angstroms (2-3 angstroms for water molecules).
[0043]
The “true aspect ratio” of the unit crystal layer 31 in the gas barrier layer 3 is extremely difficult to directly measure. The above aspect ratio Z = L / a is not necessarily equal to the “true aspect ratio” of the unit crystal layer 31 in the gas barrier layer 3. It is reasonable to approximate the “aspect ratio”.
[0044]
There is a relationship of a <d between the interplanar spacing d obtained by the powder X-ray diffraction method of the resin composition and the “unit thickness a” obtained by the powder X-ray diffraction measurement of the inorganic layered compound alone, and ( When the value of da) is equal to or greater than the width of a single resin chain in the composition, the resin is inserted between the layers of each inorganic layered compound in the resin composition. Therefore, the thickness of the unit crystal layer 31 in the gas barrier layer 3 is approximated by the “unit thickness a”, that is, the “true aspect ratio” of the unit crystal layer 31 in the gas barrier layer 3 is the above-described inorganic layered compound. There is sufficient validity to approximate by the “aspect ratio Z” in the dispersion liquid.
[0045]
As described above, the true particle size measurement of the unit crystal layer 31 in the gas barrier layer 3 is extremely difficult. However, the particle size of the unit crystal layer 31 in the resin 32 of the gas barrier layer 3 is in the dispersion ( It can be considered that it corresponds to the particle size L of the inorganic layered compound (resin / inorganic layered compound / dispersion medium).
[0046]
However, since it is considered that the particle size L in the dispersion liquid determined by the diffraction / scattering method is much less likely to exceed the major axis Lmax of the inorganic layered compound, the true aspect ratio (Lmax / a) is the present invention. The possibility of being lower than the “aspect ratio Z” used in (Lmax / a <Z) is theoretically quite low.
[0047]
From the above two points, the aspect ratio definition Z used in the present invention is considered to have sufficient validity. In the present specification, “aspect ratio” or “particle diameter” means “aspect ratio Z” defined above or “particle diameter L determined by diffraction / scattering method”.
[0048]
In view of easily giving a large aspect ratio, an inorganic layered compound having a property of swelling and cleaving in the dispersion medium is preferably used.
[0049]
The degree of the “swelling / cleavage” property of the inorganic layered compound to the dispersion medium can be evaluated by the following “swelling / cleavage” test. In the following swellability test, the swelling property of the inorganic layered compound is preferably about 5 or more (and more preferably about 20 or more). On the other hand, the cleavage property of the inorganic stratiform compound is preferably about a cleavage value of about 5 or more (and further a cleavage value of about 20 or more) in the following cleavage test. In these cases, as the dispersion medium, a liquid having a density smaller than that of the inorganic layered compound is used. When the inorganic layered compound is a natural swellable clay mineral, it is preferable to use water as the dispersion medium.
[0050]
<Swellability test>
Into a 100 mL graduated cylinder, 100 mL of the dispersion medium is added, and 2 g of the inorganic layered compound is slowly added thereto. After standing, the volume (mL) of the inorganic layered compound dispersion layer is read as a swelling value from the scale of the interface between the inorganic layered compound dispersion layer and the supernatant after 24 ° C. and 24 hours. The larger this value, the higher the swelling property.
[0051]
<Cleavage test>
Slowly add 30 g of the inorganic layered compound to 1500 mL of the dispersion medium, and circulate with a disperser [Asada Tekko Co., Ltd., Despa MH-L, blade diameter 52 mm, rotation speed 3100 rpm, container capacity 3 L, bottom-blade distance 28 mm]. After dispersing for 90 minutes at a speed of 8.5 m / sec (23 ° C.), take 100 mL of the dispersion, put it in a graduated cylinder and let stand for 60 minutes, then cleave the volume (mL) of the inorganic layered compound dispersion layer from the interface with the supernatant. Read as value.
[0052]
As the inorganic layered compound that swells and cleaves in the dispersion medium, clay minerals that swell and cleave in the dispersion medium are particularly preferably used. Such clay minerals are generally of a type having a two-layer structure having an octahedral layer with a central metal of aluminum, magnesium, etc. on the upper part of a tetrahedral layer of silica, and a tetrahedral layer of silica comprising aluminum, magnesium, etc. It is classified into a type having a three-layer structure in which an octahedral layer made of a central metal is narrowed from both sides. Examples of the former two-layer structure type include kaolinite group and antigolite group. Examples of the latter three-layer structure type include smectite group, vermiculite group and mica group depending on the number of interlayer cations. Can do.
[0053]
More specifically, these clay minerals include kaolinite, dickite, nacrite, halloysite, antigolite, chrysotile, pyrophyllite, montmorillonite, beidellite, nontronite, saponite, sauconite, stevensite, hectorite, tetra Examples include silicic mica, sodium teniolite, muscovite, margarite, talc, vermiculite, phlogopite, xanthophyllite, chlorite.
[0054]
In addition, clay minerals treated with organic substances (hereinafter sometimes referred to as organic modified clay minerals) can also be used as inorganic layered compounds (in addition, regarding clay minerals treated with organic substances, Asakura Shoten, “Clay of See Encyclopedia).
[0055]
Among the above clay minerals, the smectite group, vermiculite group and mica group are preferable, and the smectite group is more preferable from the viewpoint of swelling or cleavage. Examples of the smectite group include montmorillonite, beidellite, nontronite, saponite, soconite, stevensite, and hectorite.
[0056]
Examples of the dispersion medium for swelling or cleaving the inorganic layered compound include water, methanol, ethanol, propanol, isopropanol, ethylene glycol, diethylene glycol and other alcohols, dimethylformamide, dimethyl sulfoxide, acetone and the like in the case of natural swelling clay minerals. Alcohols such as water and methanol are more preferable.
[0057]
In the case of organically modified clay minerals, aromatic hydrocarbons such as benzene, toluene and xylene, ethers such as ethyl ether and tetrahydrofuran, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, n-pentane and n-hexane , Aliphatic hydrocarbons such as n-octane, halogenated hydrocarbons such as chlorobenzene, carbon tetrachloride, chloroform, dichloromethane, 1,2-dichloroethane, perchloroethylene, ethyl acetate, methyl methacrylate (MMA), Examples include dioctyl phthalate (DOP), dimethylformamide, dimethyl sulfoxide, methyl cellosolve, and silicone oil.
[0058]
In the foam container according to the present invention, the resin composition containing the inorganic layered compound described above is formed into a layer to form the gas barrier layer 3, and the gas barrier layer 3 is laminated on the foam container serving as a base material. There is no particular limitation. For example, the gas barrier layer 3 may be laminated after the foam container is molded first, or the gas barrier layer 3 is laminated on the foam sheet first to form a laminated foam sheet, and then molded as a container. May be.
[0059]
As a method of laminating the gas barrier layer 3 after molding the foam container first, from the method of molding the resin composition into a film and sticking it to the foam container, or a resin composition containing an inorganic layered compound The method of preparing the coating liquid which becomes and coating this coating liquid on a base material is mentioned.
[0060]
The resin used in the method for molding the resin composition into a film is not particularly limited, and any resin that does not lower the gas barrier property of the gas barrier layer 3 may be used. Further, as a method for molding the resin composition into a film, extrusion molding, calendering or the like is preferably used, but is not particularly limited.
[0061]
The foam container according to the present invention can be molded into various shapes depending on the contents to be stored and packaged. In this case, as a molding method of the gas barrier layer 3, the base is first molded into a film shape. It is preferable to use a method in which the resin composition is used as a coating liquid and the coating liquid is coated rather than the method of laminating the material.
[0062]
In the method of coating the coating liquid, since the gas barrier layer 3 can be laminated after the substrate is first molded into a desired shape, the degree of freedom in molding the foam container according to the present invention is further improved. be able to.
[0063]
The resin contained in the coating liquid is not particularly limited. For example, polyolefin resin, polyester resin, amide resin, acrylic resin, styrene resin, acrylonitrile resin, cellulose resin, halogen-containing resin, hydrogen Bonding resin, liquid crystal resin, polyphenylene oxide resin, polymethylene oxide resin, polycarbonate resin, polysulfone resin, polyether sulfone resin, polyether ether ketone resin, ethylene-vinyl acetate copolymer emulsion, acrylic resin emulsion, urethane resin And emulsions such as acrylic emulsions and acrylic-urethane copolymer emulsions.
[0064]
As an example of a preferable resin, a resin containing a high-hydrogen bonding resin having a hydrogen bonding group or an ionic group described later can be given. The content of hydrogen bonding groups or ionic groups in the high hydrogen bonding resin (when both are included, the total amount of both) is usually 20 to 60 mol%, preferably 30 to 50 mol%. is there. The content of these hydrogen bonding groups and ionic groups can be measured by, for example, nuclear magnetic resonance (NMR) techniques (1H-NMR, 13C-NMR, etc.).
[0065]
Examples of the hydrogen bonding group include a hydroxyl group, an amino group, a thiol group, a carboxyl group, a sulfonic acid group, and a phosphoric acid group. Examples of the ionic group include a carboxylate group, a sulfonic acid ion group, a phosphate ion group, and an ammonium group. And phosphonium group. More preferable examples of the hydrogen bonding group or ionic group include a hydroxyl group, an amino group, a carboxyl group, a sulfonic acid group, a carboxylate group, a sulfonic acid ion group, and an ammonium group.
[0066]
Specific examples of the high hydrogen bonding resin include, for example, polyvinyl alcohol, an ethylene-vinyl alcohol copolymer having a vinyl alcohol fraction of 40 mol% or more, polysaccharides, polyacrylic acid and esters thereof, sodium polyacrylate, Examples thereof include polystyrene sulfonic acid, sodium polystyrene sulfonate, polyethyleneimine, polyallylamine and its quaternary ammonium salt, polyvinyl thiol, polyglycerin and the like. Among the resins described above, more preferable examples include polyvinyl alcohol and polysaccharides.
[0067]
Here, the polyvinyl alcohol is, for example, a polymer obtained by hydrolysis or transesterification (saponification) of an acetate portion of a vinyl acetate polymer (that is, a copolymer of vinyl alcohol and vinyl acetate) , A polymer obtained by saponifying a vinyl trifluoroacetate polymer, a vinyl formate polymer, a vinyl pivalate polymer, a t-butyl vinyl ether polymer, a trimethylsilyl vinyl ether polymer, etc. (For details of polyvinyl alcohol, for example, Edited by Poval Society, "World of PVA", 1992, Kobunshi Publishing Co., Ltd .; Nagano et al., "Poval" 1981, Kobunshi Publishing Co., Ltd.).
[0068]
The degree of “saponification” in polyvinyl alcohol is preferably 70% or more, more preferably 85% or more, and particularly preferably 98% or more of a so-called completely saponified product. Moreover, 100 or more and 5000 or less are preferable and, as for the polymerization degree in polyvinyl alcohol, 200 or more and 3000 or less are more preferable. Furthermore, the PVA referred to in the present invention may be modified with a small amount of a copolymerization monomer as long as the object of the present invention is not impaired.
[0069]
Polysaccharides are biopolymers synthesized in biological systems by polycondensation of various monosaccharides, and here include those chemically modified based on them. Examples thereof include cellulose and cellulose derivatives such as hydroxymethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, amylose, amylopectin, pullulan, curdlan, xanthan, chitin, chitosan and the like.
[0070]
The ethylene-vinyl alcohol copolymer (hereinafter referred to as EVOH) is an EVOH having a vinyl alcohol fraction of 40 mol% to 80 mol%, more preferably 45 mol% to 75 mol%. means. The EVOH melt index (measured under conditions of a temperature of 190 ° C. and a load of 2160 g; hereinafter referred to as MI) is not particularly limited, but is 0.1 to 50 g / 10 min. Furthermore, EVOH referred to in the present invention may be modified with a small amount of a copolymerization monomer as long as the object of the present invention is not impaired.
[0071]
The modified polyvinyl alcohol and the ethylene-vinyl alcohol copolymer include, in the production process of polyvinyl alcohol, vinyl esters, particularly vinyl acetate monomers, and other unsaturated monomers copolymerizable therewith. Copolymerized. Examples of the other unsaturated monomer include olefins such as ethylene, propylene, α-hexene, α-octene, (meth) acrylic acid, crotonic acid, (anhydrous) maleic acid, fumaric acid, and itaconic acid. Unsaturated acids such as alkyl esters and alkali salts thereof, vinyl sulfonic acid, styrene sulfonic acid, sulfonic acid-containing monomers such as 2-acrylamido-2-methylpropane sulfonic acid and alkali salts thereof, dimethylaminoethyl (meta ) Acrylate, diethylaminoethyl (meth) acrylate, trimethyl-2-(-1- (meth) acrylamide-1,1-dimethylethyl) ammonium chloride, trimethyl-3- (1- (meth) acrylamidopropyl) ammonium chloride, 1-vinyl-2-ethylimidazole, Other examples include quaternizable cationic monomers, styrene, alkyl vinyl ethers, (meth) acrylamides, and others.
[0072]
The ratio of these copolymer components is not particularly limited, but is preferably about 50 mol% or less, preferably about 30 mol% or less with respect to the vinyl alcohol unit. Various forms obtained by an arbitrary method such as random copolymerization, block copolymerization, and graft copolymerization are used.
[0073]
Among these copolymers, a block copolymer obtained by copolymerizing a polycarboxylic acid component with respect to a polyvinyl alcohol component is particularly preferably used, and is particularly preferable when the polycarboxylic acid component is polymethacrylic acid. Further, the block copolymer is particularly preferably an AB type block copolymer in which a polyacrylic acid chain is extended to one end of a polyvinyl alcohol chain, and the polyvinyl alcohol block component (a) When the weight ratio (a) / (b) of the acrylic acid block component (b) is preferably 50/50 to 95/5, particularly preferable gas barrier properties are provided when it is 60/40 to 90/10, The bonding properties with the base material layer are remarkably complete. Among the other modified products, one particularly preferable embodiment is a silyl group-modified polyvinyl alcohol resin comprising a saponified vinyl ester polymer modified with at least one compound having a silyl group in the molecule. is there.
[0074]
A method for obtaining a modified polymer having such a composition is not particularly limited, but a compound having a silyl group in the molecule is added to a vinyl alcohol polymer such as polyvinyl alcohol or modified polyvinyl acetate obtained by a conventional method. Reacting to introduce a silyl group into the polymer, or activating the end of polyvinyl alcohol or a modified product thereof, introducing an unsaturated monomer having a silyl group in the molecule to the end of the polymer, and further Various types of modification methods such as graft copolymerization of monomers onto vinyl alcohol polymer molecular chains, and copolymers obtained from vinyl ester monomers and unsaturated monomers having a silyl group in the molecule , A method of saponifying this, or terminal polymerization such as polymerizing a vinyl ester in the presence of a mercaptan having a silyl group and the like. Introducing silyl groups, various methods such as are effectively used.
[0075]
As a modified polyvinyl alcohol resin obtained by such various methods, any resin having a silyl group in the molecule as a result can be used, but the silyl group contained in the molecule is an alkoxyl group or an acyloxyl group and Those having a reactive substituent such as a silanol group or a salt thereof, which is a hydrolyzate thereof, are preferred, and a silanol group is particularly preferred among them.
[0076]
Compounds having a silyl group in the molecule used to obtain these modified polyvinyl alcohol resins include trimethylchlorosilane, dimethylchlorosilane, methyltrichlorosilane, vinyltrichlorosilane, diphenyldichlorosilane, triethylfluorosilane and the like. Organosilicon esters such as organohalosilane, trimethylacetoxysilane and dimethyldiacetoxysilane, organoalkoxysilanes such as trimethylmethoxysilane and dimethyldimethoxysilane, organosilanols such as trimethylsilanol and diethylsilanediol, N-amiethyltrimethoxysilane and the like Other examples include organosilicon isocyanates such as aminoalkylsilane and trimethylsilicon isocyanate. The degree of modification by these silylating agents can be arbitrarily adjusted according to the type, amount and reaction conditions of the silylating agent used.
[0077]
Examples of the unsaturated monomer used in the method for saponifying a copolymer of a vinyl ester monomer and an unsaturated monomer having a silyl group in the molecule include vinyltrimethoxysilane, vinyltrimethylsilane. Many vinyl silane compounds such as vinyl alkoxy silanes such as ethoxy silane, vinyl methyldimethoxy silane, alkyl or allyl substitutes of vinyl alkoxy silanes typified by vinyl triisopropoxy silane, etc. And a polyalkylene glycolated vinyl silane in which a part or all of the alkoxy group is substituted with a polyalkylene glycol such as polyethylene glycol. Furthermore, (meth) acrylamide-alkylsilanes represented by 3- (meth) acrylamino-propyltrimethoxysilane, 3- (meth) acrylamide-propyltriethoxysilane and the like can also be preferably used.
[0078]
On the other hand, an alkoxysilylalkyl mercaptan such as 3- (trimethoxysilyl) -propyl mercaptan is preferred as a method for saponification after polymerizing a vinyl ester in the presence of a mercaptan having a silyl group and introducing a silyl group at the terminal. Used.
[0079]
The suitability range varies depending on the degree of modification in the modified polyvinyl alcohol resin of the present invention, that is, the content of silyl groups, the degree of saponification, etc., but it is an important factor for the gas barrier property that is the object of the present invention. . The content of the silyl group is usually 30 mol% or less, preferably 10 mol% or less, more preferably 5 mol% or less as a monomer containing a silyl group with respect to the vinyl alcohol unit in the polymer. 2 mol% or less is particularly preferably used. The lower limit is not particularly limited, but the effect is particularly remarkable when it is 0.1 mol% or more.
[0080]
The silylation rate indicates the ratio of the introduced silyl group after silylation to the amount of hydroxyl group contained in the polyvinyl alcohol resin before silylation.
[0081]
The modified polyvinyl alcohol resin into which the silyl group has been introduced is dissolved in an alcohol solvent by the presence of the introduced silyl group by heating and dissolving with an alcohol or a mixed solvent of alcohol / water. On the other hand, the modified polyvinyl alcohol resin dissolved in the solvent is cross-linked by reacting part of the introduced silyl group through a dealcoholization reaction and a dehydration reaction. In addition, the presence of water is essential for the above reaction, and it is preferable to use a mixed solvent of alcohol / water.
[0082]
Of course, these various polyvinyl alcohol resins may be used alone, but as long as they do not impair the purpose of the present invention, they may be copolymerized with other monomers that can be copolymerized or mixed. These resin compounds can be used in combination. Examples of such resins include polyacrylic acid or esters thereof, polyester resins, polyurethane resins, polyamide resins, epoxy resins, melamine resins, and others.
[0083]
The coating liquid is a liquid obtained by dispersing or dissolving the above-described inorganic layered compound and resin in a dispersion medium. From the viewpoint of gas barrier properties of the obtained foam container, the dispersion medium is preferably a liquid that swells or cleaves the inorganic layered compound described above.
[0084]
The composition ratio of the inorganic layered compound and the resin in the coating liquid is not particularly limited, but generally, the weight ratio of the inorganic layered compound to the resin (inorganic layered compound / resin) is 1/100 to 100/1. Further, it is preferably in the range of 1/20 to 10/1. The higher the weight ratio of the inorganic layered compound, the better the gas barrier properties. However, in view of the bending resistance, the range of 1/20 to 2/1 is more preferable.
[0085]
The concentration of the high hydrogen bonding resin and the inorganic layered compound in the coating solution is preferably in the range of 0.1% by weight to 70% by weight, and preferably 1% by weight to 15% by weight. % Is more preferable, and 4% to 10% by weight is even more preferable from the viewpoint of productivity.
[0086]
When the resin used for the gas barrier layer 3 of the present invention is a high hydrogen bonding tree, a hydrogen bonding group crosslinking agent can be used for the purpose of improving the water resistance of the gas barrier layer 3.
[0087]
Suitable examples of the crosslinking agent include titanium coupling agents, silane coupling agents, melamine coupling agents, epoxy coupling agents, coupling agents such as isocyanate coupling agents, water-soluble epoxy compounds, A copper compound, a zirconium compound, an organometallic compound, etc. are mentioned. From the viewpoint of improving water resistance, organometallic compounds, zirconium compounds, water-soluble epoxy compounds, and silane coupling agents are more preferably used, and organometallic compounds such as organotitanium compounds are more preferred.
[0088]
Specific examples of the zirconium compound include zirconium halides such as zirconium oxychloride, hydroxyzirconium chloride, zirconium tetrachloride and zirconium bromide; zirconium salts of mineral acids such as zirconium sulfate, basic zirconium sulfate and zirconium nitrate. Zirconium salts of organic acids such as zirconium formate, zirconium acetate, zirconium propionate, zirconium caprylate, zirconium stearate; ammonium zirconium carbonate, sodium zirconium sulfate, ammonium zirconium acetate, sodium zirconium oxalate, zirconium zirconium citrate, citric acid Examples include zirconium complex salts such as zirconium ammonium.
[0089]
Specific examples of the water-soluble epoxy compound include sorbitol polyglycidyl ether, sorbitan polyglycidyl ether, glycidyl ether epoxy resin, heterocyclic epoxy resin, glycidyl amine epoxy resin, or aliphatic epoxy resin. it can.
[0090]
Examples of the silane coupling agent include amino silane coupling agents, vinyl or methacryloxy silane coupling agents, epoxy silane coupling agents, methyl silane coupling agents, chloro silane coupling agents, and mercapto. Silane coupling agent system.
[0091]
Furthermore, as a suitable example of the crosslinking agent for the hydrogen bonding group, a reaction that forms a crosslinked structure by reacting with a plurality of functional groups of the high hydrogen bonding resin, that is, an organometallic compound that can undergo a crosslinking reaction, for example, polyvinyl The above-mentioned organometallic compound in which the metal atom of the organometallic compound and the oxygen atom of the hydroxyl group react with a plurality of hydroxyl groups of the alcohol to form a cross-linking bond by coordination bond or ionic bond is preferable.
[0092]
The organometallic compound capable of undergoing a crosslinking reaction has higher crosslinking reactivity and higher crosslinking efficiency than inorganic metal salts. However, if the crosslinking reactivity is too high, the crosslinking reaction proceeds in the coating solution and coating (coating) becomes impossible. However, the crosslinking reactivity of the organometallic compound can be changed by changing the ligand as appropriate. Easy to control. The organometallic compound is superior to the inorganic metal salt in that it has an advantage that the reactivity can be easily controlled. Among organometallic compounds, in particular, an organometallic compound having a chelating ligand such as acetylacetonate has moderate crosslinking reactivity and is preferable as a crosslinking agent for a hydrogen bonding group.
[0093]
Preferable examples of such organometallic compounds include organotitanium compounds, organozirconium compounds, organoaluminum compounds, and organosilicon compounds.
[0094]
Specific examples of the organic titanium compound include tetra-normal butyl titanate, tetraisopropyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, tetramethyl titanate, etc., titanium acetylacetonate, titanium tetraacetylacetonate , Titanium chelates such as polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate, titanium triethanolamate, titanium ethylacetoacetate, and titanium acylates such as polyhydroxytitanium stearate.
[0095]
Specific examples of the organic zirconium compound include zirconium normal propylate, zirconium normal butyrate, zirconium tetraacetylacetonate, zirconium monoacetylacetonate, zirconium bisacetylacetonate, zirconium acetylacetonate bisethylacetoacetate and the like.
[0096]
Specific examples of the organoaluminum compound include aluminum acetylacetonate and aluminum organic acid chelate. Examples of the organosilicon compound include a silicon compound having a ligand that the compound exemplified as the organotitanium compound or the organozirconium compound has.
[0097]
Among these, chelate compounds are preferable in terms of stability in the coating liquid. Moreover, in terms of the stability of the coating liquid, the stability is greatly improved by setting the coating liquid to be acidic. As said acidic conditions, pH 5 or less is preferable and pH 3 or less is more preferable. There is no particular lower limit on the pH of the coating solution, but it is usually at least pH 0.5. As the addition method, it is preferably used after diluting with alcohols. By including the mixing process of said resin and a crosslinking agent, the gas barrier layer 3 by which said resin was bridge | crosslinked can be obtained.
[0098]
The addition amount of the cross-linking agent is not particularly limited, but the ratio K (K = CN / HN) of the number of moles (CN) of the cross-linking groups of the cross-linking agent to the number of moles of hydrogen bonding groups (HN) of the resin It is preferable to use it in the range of 0.001 or more and 10 or less. The mole ratio K is more preferably in the range of 0.01 to 1.
[0099]
The blending or manufacturing method of the resin composition comprising the above-described inorganic layered compound and resin is not particularly limited. From the point of uniformity during mixing or ease of operation, for example, a solution obtained by dissolving a resin in a solvent and a dispersion obtained by previously swelling and cleaving an inorganic layered compound with a dispersion medium are mixed, and then the solvent and the dispersion medium are mixed. (Method 1), and a method of removing the dispersion medium after mixing the dispersion liquid obtained by swelling and cleaving the inorganic layered compound with the dispersion medium and dissolving the resin in the dispersion medium (Method 2) ), Adding an inorganic layered compound to a solution obtained by dissolving a resin in a solvent, swelling and cleaving the inorganic layered compound using the solvent as a dispersion medium to obtain a dispersion, and removing the solvent (Method 3); A method (method 4) of thermally kneading the inorganic layered compound can be used. From the viewpoint of easily obtaining a large aspect ratio of the inorganic layered compound, the former three methods are preferably used. Moreover, in the former three, it is more preferable from the viewpoint of the dispersibility of an inorganic layered compound to process using a high pressure dispersion device.
[0100]
Examples of the high-pressure dispersing device include an ultra-high pressure homogenizer (trade name: Microfluidizer) manufactured by Microfluidics Corporation or a nanomizer manufactured by Nanomizer, and other examples include a Manton Gorin type high-pressure dispersing device such as a homogenizer manufactured by Izumi Food Machinery.
[0101]
In the above three methods, after removing the solvent and the dispersion medium from the system and laminating, the resulting foam container is heat-aged at, for example, 110 ° C. or more and 220 ° C. or less. Water resistance (meaning gas barrier property after a water-resistant environmental test) can be improved, which is preferable.
[0102]
The aging time is not limited, but it is necessary that the foam container reaches at least the set temperature. For example, in the case of a method using contact with a heating medium such as a hot air dryer, it is preferably 1 second or more and 100 minutes or less. There is no particular limitation on the heat source, and various methods such as hot roll contact, heat medium contact (air, oil, etc.), infrared heating, microwave heating and the like can be applied. The aging treatment exhibits a particularly excellent effect in improving water resistance when the resin contains a high hydrogen bonding resin.
[0103]
As shown in FIG. 5, the high-pressure dispersion treatment in the present invention refers to high shearing or high shearing by passing a composition mixed solution in which particles to be dispersed or a dispersion medium or the like are caused to pass through and collide with a plurality of thin tubes 11. Dispersion treatment under special conditions such as high pressure.
[0104]
In such a high-pressure dispersion treatment, the composition mixture is preferably passed through a narrow tube 11 having a tube diameter of 1 μm to 1000 μm, and the maximum pressure condition is 100 kgf / cm when passing through the thin tube 11. ² The above pressure is preferably applied, and further 500 kgf / cm. ² More preferably, more preferably 1000 kgf / cm ² That's it. Further, when the composition mixed solution passes through the narrow tube 11, the maximum arrival speed of the composition mixed solution preferably reaches 100 m / s or more, and the heat transfer rate is preferably 100 kcal / hr or more.
[0105]
The principle of the high-pressure treatment in the high-pressure dispersion treatment apparatus used for the high-pressure dispersion treatment will be schematically explained. First, the composition mixture is sucked by the pump 12 into the feeder tube 13 having a tube diameter larger than that of the thin tube 11. It is captured. Subsequently, a high pressure is applied to the composition mixture in the feeder tube 13 by the pump 12. At this time, the composition mixed solution in the feeder tube 13 is pushed out toward the thin tube 11 by a backflow prevention valve (not shown) provided in the feeder tube 13. Therefore, the composition mixed solution is in a high pressure and high speed state in the thin tube 11, and the inorganic layered compound particles of the composition mixed solution collide with each other and the inner wall of the thin tube 11, so that the diameter of each inorganic layered compound particle is increased. And the thickness, particularly the thickness, is subdivided and more uniformly dispersed and taken out from the discharge pipe 14.
[0106]
For example, when the flow velocity at the point where the maximum velocity is instantaneously reached is, for example, 300 m / s with respect to the composition mixed solution which is the processing sample in the thin tube 11 portion, the volume is 1 × 10. ^-3 m ^Three 1 / (3 × 10 ^Five ) When it passes in sec and the temperature of the composition mixture rises by 35 ° C., energy is transferred to the composition mixture by pressure loss. As for the heat transfer rate, the specific gravity of the composition mixture is 1 g / cm. ^Three 3.8 × 10 at specific heat of 1 cal / g ° C. ^Four kcal / hr.
[0107]
In the foam container according to the present invention, surface treatment, for example, corona treatment, flame plasma treatment, ozone treatment, electron beam irradiation treatment, on each interface between the above-described gas barrier layer 3 and the foam container as a base material, Anchor processing may be performed. The anchor treatment is to form an anchor layer between the gas barrier layer 3 and the foam container surface. Specifically, for example, as shown in FIG. 6, an anchor layer 2 is laminated on the container 1, and a gas barrier layer 3 having an inorganic layered compound is laminated on the anchor layer 2.
[0108]
The material of the anchor layer 2 is not particularly limited, but preferably contains an isocyanate compound and an active hydrogen compound.
[0109]
Examples of the isocyanate compound contained in the anchor layer 2 include tolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), hexamethylene diisocyanate (HDI), and 4,4′-methylene. Biscyclohexyl isocyanate (H12MDI), isophorone diisocyanate (IPDI) and the like can be mentioned.
[0110]
The active hydrogen compound may be any compound having a functional group capable of binding to an isocyanate compound, such as ethylene glycol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl. Low molecular weight polyols such as glycol and trimethylolpropane, polyethylene glycol, polyoxypropylene glycol, ethylene oxide / propylene oxide copolymer, polyether polyol such as polytetramethylene ether glycol, poly-β-methyl-δ-valerolactone, poly Examples include polyester polyols such as caprolactone and polyesters from diol / dibasic acids.
[0111]
In the active hydrogen compound, a low molecular weight polyol is particularly preferable, and a diol in the low molecular weight polyol is more preferable. Here, the diol is ethylene glycol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, etc., and adipic acid, azelaic acid, sebacic acid, isophthalic acid as dibasic acids Terephthalic acid and the like. Other polyols include active hydrogen compounds such as castor oil, liquid polybutadiene, epoxy resin, polycarbonate diol, acrylic polyol, and neoprene.
[0112]
The mixing ratio of the isocyanate compound and the active hydrogen compound is not particularly limited, but the addition amount is preferably determined in consideration of the equivalent relationship between the isocyanate group and the active hydrogen group, for example, —OH, —NH, —COOH. For example, the ratio R (R = AN / BN) of the number of moles of isocyanate groups (AN) to the number of moles of active hydrogen groups (BN) of the active hydrogen compound is within the range of 0.001 or more and 10 or less. It is preferable to use for. The mole ratio R is more preferably in the range of 0.01 or more and 1 or less. When the mole ratio R is less than 0.001, the adhesive strength is poor, and when it exceeds 10, the tackiness is too high, and blocking becomes a problem.
[0113]
A method for laminating the anchor layer 2 on the foam container 1 as a base material is not particularly limited, but a coating method using an anchor coating agent solution by dissolving an anchor coating agent containing an isocyanate compound and an active hydrogen compound in a solvent. Is preferred. Specifically, as the coating method, a direct gravure method, a reverse gravure method, a micro gravure method, a two-roll beat coating method, a roll coating method such as a bottom feed three-pin reverse coating method, a doctor knife method or a die coating method, Examples thereof include a dip coating method (dipping method), a bar coating method, a spray coating method, a spin coating method, and a coating method combining these.
[0114]
In addition, the solvent component in the anchor coating agent solution is mainly an organic solvent, and alcohols, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, esters, ketones, ethers, halogenated carbons. Hydrogen and these mixed solvents are mentioned.
[0115]
Although the coating thickness which apply | coated the anchor coating agent solution to the container 1 at the film form is not specifically limited, It is preferable to set so that dry thickness may be set to 0.01 micrometer-5 micrometers. The greater the coating thickness, the better the heat seal strength, but the lower the gelboflex resistance. Therefore, the coating thickness is more preferably 0.03 μm to 2.0 μm, and still more preferably 0.05 μm to 1.0 μm.
[0116]
The stack of the gas barrier layer 3 in the present invention is preferably formed on the anchor layer 2. At this time, in order to improve the adhesion between the anchor layer 2 and the gas barrier layer 3, the gas barrier layer 3 is formed. It is preferable that contains a surfactant. The surfactant is not particularly limited as long as it can improve the adhesion between the gas barrier layer 3 and the anchor layer 2, and conventionally known surfactants, for example, anionic surfactants, A cationic surfactant, a nonionic surfactant, etc. can be mentioned.
[0117]
Examples of the anionic surfactant include aliphatic monocarboxylates, carboxylic acid types such as N-acyloyl glutamate, sulfonic acids such as alkylbenzene sulfonate, naphthalene sulfonate-formaldehyde condensate, and sulfosuccinic acid dialkyl ester. Hydrocarbon anionic surfactants, such as sulfuric acid ester type such as alkyl sulfate, alkyl sulfate polyoxyethylene salt, phosphoric acid ester type such as alkyl phosphate, boric acid ester type such as alkyl borate, Fluorine anionic surfactants such as sodium perfluorodecanoate and sodium perfluorooctyl sulfonate, and silicone anionic surfactants having an anionic group such as a polymer having a polydimethylsiloxane group and a carboxylic acid metal salt Is mentioned.
[0118]
Examples of the cationic surfactant include amine salt types such as alkylamine salts, and quaternary ammonium salt types such as alkyltrimethylammonium salts, dialkyldimethylammonium salts, and alkyldimethylbenzylammonium salts.
[0119]
Examples of the zwitterionic surfactant include carboxybetaine type such as N, N-dimethyl-N-alkylaminoacetic acid betaine, and glycine type such as 1-alkyl-1-hydroxyethyl-1-carboxymethylimidazolinium betaine. It is done.
[0120]
Nonionic surfactants include ester types such as glycerin fatty acid ester, sorbitan fatty acid ester, and sucrose fatty acid ester, polydimethylsiloxane group and alkylene oxide adduct condensation polymer, polysiloxane-polyoxyalkylene copolymer, Ether type such as polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene polyoxypropylene block polymer, ester ether type such as polyethylene glycol fatty acid ester, polyoxyethylene sorbitan fatty acid ester, alkanol such as aliphatic alkanolamide Examples include amide type, fluorine type such as perfluorodecanoic acid-diglycerin ester and perfluoroalkylalkylene oxide compounds.
[0121]
Among the above surfactants, ether type nonionic surfactants such as alkali metal salts of carboxylic acids having an alkyl chain having 6 to 24 carbon atoms, polydimethylsiloxane-polyoxyethylene copolymer ( Silicone nonionic surfactants) and fluorine-type nonionic surfactants (fluorine-based nonionic surfactants) such as perfluoroalkylethylene oxide compounds are preferred.
[0122]
When the gas barrier layer 3 is formed, for example, when a coating solution is used, the amount of the surfactant added is preferably 0.001 to 5% by weight in the coating solution from the viewpoint of the effect. -0.5 wt% is more preferable, and 0.005-0.1 wt% is particularly preferable.
[0123]
In the foam container according to the present invention, the base resin used as the container 1 for laminating the gas barrier layer 3 and the anchor layer 2 described above is not particularly limited. Specific examples of the base resin include polyethylene resin, polypropylene resin, polystyrene resin, silicone resin, cellulose acetate resin, epoxy resin, phenol resin, urea resin, urethane resin, polyvinyl chloride resin, polyamide resin, and polyester resin. And foamed elastomer resin.
[0124]
Among them, in the container 1, in particular, a polyethylene resin and a polypropylene resin are preferable, and a polypropylene resin is more preferable in terms of heat resistance. From the viewpoint of foamability, polystyrene resin is more preferable. The expansion ratio is preferably 1.5 to 50 times, and more preferably 2 to 20 times. There is no particular limitation on the foaming method, and solvent foaming using butane, chlorofluorocarbon, etc., chemical foaming using azo compound or carbonic acid compound, gas foaming using carbon dioxide gas, water, air, nitrogen gas etc. are preferably used. It is done.
[0125]
The method of further laminating the gas barrier layer 3 on the surface of the container 1 on which the anchor layer 2 is laminated is not particularly limited, but the coating liquid for applying the resin composition coating liquid to the surface of the container 1, drying, and heat treatment is performed. A method, a method of laminating the resin composition film on the anchor layer 2 later, and the like are preferable, and a method of performing the above coating is particularly preferable.
[0126]
Coating methods include direct gravure method, reverse gravure method, micro gravure method, roll coating method such as two roll beat coating method, bottom feed three reverse coating method, doctor knife method, die coating method, dip coating method (dipping method) Method), spray coating method, spin coating method, bar coating method and coating method combining these.
[0127]
The film thickness of the gas barrier layer 3 is preferably 10 μm or less, more preferably 1 μm or less, and particularly preferably in the range of 0.1 to 1 μm. In order to obtain gas barrier properties having sufficient effectiveness, the film thickness of the gas barrier layer 3 is preferably 1 nm or more.
[0128]
In the container 1, the surface on which the gas barrier layer 3 is laminated may be either the inner surface or the outer surface. If the said gas barrier layer 3 in this invention is laminated | stacked on at least one of the inner surface and outer surface of the container 1, the outstanding gas barrier property can be exhibited.
[0129]
The gas barrier layer 3 formed by the laminating method as described above can exhibit an excellent gas barrier property regardless of the shape of the container 1 molded in advance, and also has an impact resistance and is a very excellent foam container. It can be. Moreover, if the film thickness of the formed gas barrier layer 3 is in the above range, the gas barrier layer 3 as a different material that hinders recycling is reduced, so that recyclability and incineration suitability can be improved.
[0130]
In the foam container according to the present invention, a sealant layer 4 for improving heat sealability may be further laminated on the gas barrier layer 3 as shown in FIG. The resin used for the sealant layer 4 is not particularly limited, but due to the problems of desorption such as heat seal strength, food fragrance, and resin odor, polyethylene (low density, high density), ethylene-propylene copolymer, ethylene-butene copolymer. Polymer, ethylene-hexene copolymer, ethylene-4-methyl-1-pentene copolymer, ethylene-octene copolymer, polypropylene, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, ethylene- Polyolefin resins such as methyl acrylate copolymer, ethylene-acrylic acid copolymer, ionomer resin, and ethylene-vinyl alcohol copolymer; polyacrylonitrile resin (PAN); polyester resin; and the like are preferably used.
[0131]
The sealant layer 4 is preferably a sealant having a high impact strength, particularly when sealing of the contents is required. As such a resin, a metallocene catalyst or a late transition metal complex catalyst was used. Polyolefin resins such as polyethylene, ethylene-α-olefin copolymers, and polypropylene are also used.
[0132]
The method for laminating the sealant layer 4 is not particularly limited. For example, the resin used in the sealant layer 4 is dissolved in a solvent and coated on the gas barrier layer 3 made of an inorganic layered compound and the resin. Preferred examples include a method of extrusion laminating on the gas barrier layer 3 and a method of dry laminating the sealant layer 4 on the gas barrier layer 3. Further, the interface between the sealant layer 4 and the gas barrier layer 3 may be subjected to treatment such as corona treatment, flame plasma treatment, ozone treatment, electron beam treatment or anchor coating agent.
[0133]
In addition, various kinds of agents such as an ultraviolet absorber, a crosslinking agent, a colorant, and an antioxidant are applied to at least one of the container 1, the anchor layer 2, the gas barrier layer 3, and the sealant layer 4 as long as the effects of the present invention are not impaired. Additives may be mixed.
[0134]
The foam container according to the present invention has an oxygen permeability of 1 mL / m. ² ・ Day ・ atm or less, preferably 0.1mL / m ² ・ Day ・ atm or less, more preferably 0.05mL / m ² ・ It is below day ・ atm. Therefore, in the above-mentioned foam container, it is possible to effectively suppress the entry of oxygen or the like from the outside air into the foam container, and it is possible to avoid rapid deterioration of the contents. Can be stored for a long time.
[0135]
The shape of the foam container according to the present invention is not particularly limited, and specifically, for example, a tray, a cup, a pair of a vacuum / pneumatic molded container and a lid, an injection or press molded container and a lid Examples include pairs with materials, squeeze bottles, bag-in-boxes, brick-shaped containers, gable tops, composite containers, laminated tubes, plastic can containers, square bottom bag containers, paper carton containers, bottles, tanks, and the like.
[0136]
The foam container according to the present invention is suitably used for storing and packaging heated, refrigerated or frozen items as contents. Specific examples of the contents at this time include, for example, foods. It is done.
[0137]
Of the above foods, for example, fresh foods such as sugar beet, processed meat products, and processed fish products are important for freshness, and are often easily rotted and deteriorated, so that they often need to be refrigerated or frozen. Furthermore, the fresh food is easily deteriorated by contact with air or evaporation of moisture or the like. Therefore, a foam container having the gas barrier layer 3 according to the present invention is particularly suitable as a packaging material or container that keeps the refrigerated or frozen state for a long time and further suppresses contact with outside air and evaporation of volatile components. Is preferred.
[0138]
On the other hand, instant foods such as cup noodles and foods for microwave ovens are often cooked with hot water or cooked by heating with a microwave oven. The foam container according to the present invention is suitably used as a container for storing and packaging processed foods that require heating.
[0139]
Since the foam container according to the present invention has excellent gas barrier properties, it is possible to more effectively suppress the deterioration of the contents (food) stored and packaged in the foam container. Therefore, long-term storage can be made possible.
[0140]
In addition, since the foam container according to the present invention has heat insulation and heat resistance, it can be cooked by adding hot water to the food that is the contents, or cooked by heating with a microwave oven, Users can cook without feeling much heat. In particular, since the gas barrier layer 3 has microwave resistance, the gas barrier layer 3 itself is not heated even when heated by a microwave oven, and therefore, the temperature rise of the entire container can be further suppressed. . That is, the foam container can be used as a cooking container.
[0141]
Further, because of the heat insulation and heat resistance of the foam container, the user can also hold and eat the foam container containing the cooked food as it is, so the foam container can also be used as tableware. can do.
[0142]
In addition, the above-mentioned foam container has few gas barrier layers 3 as a different material like a conventional foam container, and does not contain chlorine or the like like a polyvinylidene chloride resin. Therefore, since the foam container according to the present invention can be improved in recyclability and incineration characteristics, it is easy to dispose and recycle after use, and is very suitable as a container for instant food.
[0143]
Specific examples of the instant food include types that are cooked by adding hot water such as cup ramen, yakisoba, and spaghetti; types that are cooked using a microwave oven such as cooked rice, curry, stew, and the like. It is not a thing.
[0144]
Moreover, since the foam container concerning this invention is lightweight and has a certain amount of intensity | strength, it can be used also for the packaging of the food which does not need to perform processing, such as refrigeration or freezing, and heating especially. Specifically, some confectionery and snacks are fine in shape and soft and unstable. If these foods are stored in the foam container, the foam container can be used as a dish. Can be used. In addition, confectionery and snacks can be stored for a longer period of time.
[0145]
Needless to say, the foam container according to the present invention is suitable when the confectionery or snacks need to be heated or need to be kept refrigerated or frozen. That is, the foam container concerning this invention can be used very suitably as a packaging material for foodstuffs.
[0146]
Moreover, the foam container according to the present invention is suitable for packaging quasi-drugs including medicines and toiletries, and packaging of electronic materials due to its gas barrier properties, heat insulation properties, and recyclability. .
[0147]
As described above, the foam container according to the present invention is formed by laminating a gas barrier layer made of a resin composition having an inorganic layered compound on a foam container. Therefore, an excellent gas barrier property can be imparted to the foam container, and a gas barrier layer that is much thinner than the conventional one can be obtained, so that the recyclability and the incineration suitability can be improved.
[0148]
In addition, since the food packaging material according to the present invention is provided with the above-mentioned foam container, the deterioration of the contents is more effectively suppressed as compared with the conventional food packaging material, and the long-term Can be stored. Therefore, it is not limited to foods in particular, and can be used for any packaging that takes such a form.
[0149]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention in detail, this invention is not limited to these.
In the examples and comparative examples, various physical properties of the gas barrier layer of the foam container (food packaging material) were measured as follows.
[0150]
[Thickness measurement]
The thickness of 0.5 μm or more was measured with a commercially available digital thickness gauge (contact thickness gauge, trade name: ultra-high precision deci-micro head MH-15M, manufactured by Nippon Optical Co., Ltd.). On the other hand, when the thickness is less than 0.5 μm, the actual coating film is formed by gravimetric analysis (the weight measurement value of a film of a certain area is divided by the area, and further divided by the specific gravity of the resin composition) or the IR method. A calibration curve of thickness and IR absorption was prepared and obtained from the calibration curve. Furthermore, in the case of measurement regarding the film thickness of the coating film of the resin composition of the present invention, the elemental analysis method (the specific inorganic element analysis value of the foam container (derived from the barrier layer) and the specific element fraction of the inorganic layered compound alone) It was based on the method of calculating | requiring the ratio of the barrier layer and container of this invention from ratio.
[0151]
(Particle size measurement)
Using a laser diffraction / scattering particle size distribution analyzer (LA910, manufactured by Horiba, Ltd.), the volume-based median diameter of particles considered to be inorganic layered compounds present in the resin matrix of the medium was measured as the particle size L. . The dispersion liquid stock solution was measured with a paste cell at an optical wavelength of 50 μm, and the dispersion liquid was measured with a flow cell method at an optical wavelength of 4 mm.
[0152]
[Aspect ratio calculation]
Using an X-ray diffractometer (XD-5A, manufactured by Shimadzu Corporation), diffraction measurement was performed by a powder method of the inorganic layered compound alone and the resin composition. Thereby, the unit thickness a of the inorganic layered compound was determined, and further, from the diffraction measurement of the resin composition, it was confirmed that there was a portion where the interplanar spacing d of the inorganic layered compound was widened. Using the particle diameter L obtained by the above method, the aspect ratio Z was calculated by the equation Z = L / a.
[0153]
(Oxygen permeability measurement)
Based on JIS K7126, it measured on 23 degreeC and 50% RH conditions with the oxygen-permeation-measuring apparatus (OX-TRANML: product made by MOCON).
[0154]
[Example 1]
1410 g of ion-exchanged water (specific electrical conductivity 0.7 μS / cm or less) is added to a dispersion kettle [trade name: Despa MH-L, manufactured by Asada Tekko Co., Ltd.], and polyvinyl alcohol [PVA117H; , Saponification degree: 99.6%, polymerization degree 1700], heated to 95 ° C. under low speed stirring (1500 rpm, peripheral speed 4.10 m / min), stirred for 1 hour and dissolved.
[0155]
Next, the temperature is lowered to 60 ° C. with stirring, and then 15 g of 1-butanol is added dropwise so that the final 1-butanol fraction becomes 1% by weight. Then, 25 g of natural montmorillonite [Kunipia F; manufactured by Kunimine Kogyo Co., Ltd.] was added as powder, and after confirming that montmorillonite was almost precipitated in the liquid, high-speed stirring (3100 rpm, peripheral speed 8.47 m / min) was performed. It was performed for 90 minutes to obtain a resin composition mixed solution (A) having a total solid content concentration of 5 wt%. (The particle size of the cleaved natural montmorillonite (Kunipia F) is 560 nm, the a value obtained from powder X-ray diffraction is 1.2156 nm, and the aspect ratio (Z) is 200 or more.)
Further, a liquid obtained by adding 0.18 g of nonionic surfactant SH3746 [polyoxyethylene-methylpolysiloxane copolymer, manufactured by Toray Dow Corning Co., Ltd.] to a mixed liquid of 92 g of 1-butanol and 277 g of isopropyl alcohol. Is (B).
[0156]
Liquid (B) is gradually added to liquid (A) under low speed stirring (1500 rpm, peripheral speed 4.10 m / min), and titanium acetylacetonate [TC100, manufactured by Matsumoto Pharmaceutical Co., Ltd.] is further stirred at low speed. Under the condition (1500 rpm, peripheral speed 4.10 m / min), 3.3 g was gradually added, and this was designated as coating solution 1.
[0157]
An anchor coating agent [ADCOAT AD335 / CAT10 = 15/1 (weight ratio): manufactured by Toyo Morton Co., Ltd.] was applied to a foamed polystyrene (PS) cup by vacuum molding having a thickness of 1.5 mm by a dipping method. The dry thickness of the anchor coat layer was 0.15 μm.
[0158]
Furthermore, the coating liquid 1 was applied as a TOP coating liquid by a dipping method to obtain a foamed PS cup as a foam container in which a gas barrier layer based on the coating liquid 1 was formed on the anchor coating layer. The dry thickness of the gas barrier layer was 0.2 μm. The recyclability of this foamed PS cup was good.
[0159]
[Example 2]
In Example 1, a foamed PP cup as a foam container according to the present invention was obtained in the same manner except that a foamed polypropylene (PP) cup was used instead of the foamed PS cup. The dry thickness of the gas barrier layer was 0.2 μm. The recyclability of this foamed PP cup was good.
[0160]
Thus, it can be seen that the foam container and the food packaging material according to the present invention have very excellent recyclability as is apparent from the results of the above Examples and Comparative Examples.
[0161]
【The invention's effect】
The foam container according to claim 1 of the present invention has a structure in which a gas barrier layer made of a resin composition having an inorganic layered compound is laminated on a resin foam layer as described above.
[0162]
As described above, the foam container according to the second aspect of the present invention, in addition to the configuration according to the first aspect, the resin foam is molded as a container in advance, and the gas barrier layer is inorganic. It is the structure laminated | stacked by coating at least one of the inner surface and outer surface of the said container with the coating liquid which consists of a resin composition which has a layered compound.
[0163]
The foam container according to claim 3 according to the present invention is configured as described above, in addition to the structure according to claim 1 or 2, wherein the container is formed by a vacuum forming method or a pressure forming method. It is.
[0164]
As described above, the foam container according to claim 4 of the present invention has a structure formed by a vacuum forming method or a pressure forming method in addition to the structure according to claim 3. .
[0165]
As described above, the foam container according to the fifth aspect of the present invention has an oxygen permeability of 1 mL / m in addition to the configuration according to any one of the first to fourth aspects. ² ・ Day ・ Atm or less.
[0166]
As described above, the foam container according to claim 6 of the present invention swells and cleaves in the dispersion medium in addition to the structure according to any one of claims 1 to 5. It is a configuration.
[0167]
The foam container according to claim 7 according to the present invention is, as described above, a resin composition in which the gas barrier layer includes an inorganic layered compound in addition to the structure according to any one of claims 1 to 5. This mixture is obtained by high-pressure dispersion treatment.
[0168]
The foam container according to claim 8 according to the present invention has a high-pressure dispersion treatment of 100 kgf / cm in addition to the structure according to claim 7 as described above. ² It is the structure processed by the above pressure conditions.
[0169]
As described above, the foam container according to the ninth aspect of the present invention has an aspect ratio of the inorganic layered compound in the range of 50 to 5000 in addition to the structure according to any one of the first to eighth aspects. It is the structure which is in.
[0170]
The foam container according to claim 10 according to the present invention has an aspect ratio of the inorganic layered compound in the range of 200 to 3000 in addition to the structure according to any one of claims 1 to 9 as described above. It is the composition which is.
[0171]
In the foam container according to claim 11 according to the present invention, as described above, in addition to the configuration according to any one of claims 1 to 10, the resin composition contains a high hydrogen bond resin, The weight ratio between the inorganic layered compound and the high hydrogen bonding resin is in the range of (1/100) to (100/1).
[0172]
As described above, the foam container according to the twelfth aspect of the present invention, in addition to the structure according to the eleventh aspect, is characterized in that the high hydrogen bond resin contains a mole of hydrogen bond groups or ionic groups per resin unit weight. % Is 30% or more and 50% or less.
[0173]
As described above, in the foam container according to the thirteenth aspect of the present invention, in addition to the structure according to the eleventh or twelfth aspect, the high hydrogen bonding resin may be polyvinyl alcohol and a modified product thereof, a polysaccharide or ethylene- It is the structure which is a vinyl alcohol copolymer and its modified body.
[0174]
Therefore, in the above configuration, since the gas barrier layer made of the resin composition having the inorganic layered compound is formed in the foam container, the foam having excellent gas barrier properties, heat resistance, heat insulation properties, recyclability, incineration suitability, etc. There exists an effect that a body container can be provided.
[0175]
As described above, the food packaging material according to the fourteenth aspect of the present invention has the foam container according to any one of the first to thirteenth aspects.
[0176]
Therefore, in the said structure, while serving as a cooking container and tableware, there exists an effect that the packaging material for foods which can preserve | save the contents over a long period of time can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a gas barrier layer included in a foam container according to an embodiment of the present invention.
FIG. 2 is an X-ray diffraction graph of an inorganic layered compound for calculating “unit thickness a” of the inorganic layered compound in the foam container.
FIG. 3 is an X-ray diffraction graph of the inorganic layered compound for calculating the “face spacing d” of the inorganic layered compound in the foam container.
4 calculates the “plane spacing d” of the inorganic layered compound when it is difficult to detect the peak corresponding to “plane spacing d” overlapping the halo (or background) in the graph of FIG. It is an X-ray diffraction graph.
FIG. 5 is an explanatory view schematically showing a high-pressure dispersion treatment used in manufacturing the gas barrier layer of the foam container.
FIG. 6 is a schematic cross-sectional view showing an example of a cross-sectional structure of a foam container according to an embodiment of the present invention.
FIG. 7 is a schematic sectional view showing another example of the sectional structure of the foam container according to the embodiment of the present invention.
[Explanation of symbols]
1 container
2 Anchor layer
3 Gas barrier layer
4 Sealant layer

Claims (13)

On the resin foam layer, a gas barrier layer made of a resin composition having an inorganic layered compound, a high hydrogen bonding resin and an organometallic compound having a chelating ligand is laminated ,
A foam container , wherein the high hydrogen bonding resin is polyvinyl alcohol and a modified product thereof, or an ethylene-vinyl alcohol copolymer and a modified product thereof . The resin foam is molded as a container in advance,
The foam container according to claim 1, wherein the gas barrier layer is laminated by coating at least one of an inner surface and an outer surface of the container with a coating liquid comprising a resin composition having an inorganic stratiform compound. .   The foam container according to claim 1 or 2, wherein the container is formed by a vacuum forming method or a pressure forming method.   2. The foam container according to claim 1, wherein the laminated foam having the gas barrier layer is formed by vacuum forming or pressure forming. The foam container according to any one of claims 1 to 4, wherein the oxygen permeability is 1 mL / m ² · day · atm or less.   The foam container according to any one of claims 1 to 5, wherein the inorganic layered compound swells and cleaves in a dispersion medium.   The foam container according to any one of claims 1 to 5, wherein the gas barrier layer is obtained by high-pressure dispersion treatment of a mixed solution of a resin composition having an inorganic stratiform compound. The foam container according to claim 7, wherein the high-pressure dispersion treatment is performed under a pressure condition of 100 kgf / cm ² or more.   The foam container according to any one of claims 1 to 8, wherein the inorganic layered compound has an aspect ratio in the range of 50 to 5,000.   The foam container according to any one of claims 1 to 9, wherein the inorganic layered compound has an aspect ratio in the range of 200 to 3,000.   The resin composition includes a high hydrogen bonding resin, and a weight ratio of the inorganic layered compound to the high hydrogen bonding resin is in a range of (1/100) to (100/1). The foam container according to any one of 1 to 10.   12. The foam container according to claim 11, wherein the high hydrogen bond resin has a mol% of hydrogen bond groups or ionic groups per unit weight of the resin of 30% or more and 50% or less. A food packaging material comprising the foam container according to any one of claims 1 to 12.

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