JP4278397B2 - Gas barrier composition and gas barrier film using the same - Google Patents

Description

【００５５】
【発明の効果】
この発明によると、ポリアクリルアミドと、金属アルコキシドの加水分解物及び／又はその縮合物とが重縮合反応するので、有機物と無機物とが複合した緻密な構造体ができ、この隙間を所定の架橋剤が架橋で埋めた非常に緻密で強固な構造の膜が生成する。さらに、所定の架橋剤は、上記構造体内の親水性基と容易に反応し、速やかにこれらを疎水化するため、耐熱水性に優れた膜となる。さらにまた、ポリアクリルアミドの効果で基材密着性が向上するため、高湿度条件下で優れた酸素ガスバリア性を発揮するコートフィルムが得られる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas barrier composition and a gas barrier film using the same.
[0002]
[Prior art]
In the field of food and medicine packaging, packaging materials having excellent gas barrier properties such as oxygen gas barrier properties are used for the purpose of preventing quality deterioration of contents. As such a gas barrier film, a film in which polyvinylidene chloride is laminated, a film using a polyvinyl alcohol resin, and the like are known. In particular, a film in which the above-mentioned polyvinylidene chloride is laminated is widely used for food packaging.
[0003]
However, the film in which the polyvinylidene chloride is laminated tends to be refrained from use due to environmental problems such as dioxin in recent years. Moreover, since the film using the said polyvinyl alcohol-type resin contains a hydroxyl group, it has the problem that the gas barrier property under high humidity falls.
[0004]
On the other hand, as a method for improving gas barrier properties under high humidity, a composite polymer obtained by polycondensation of a composition containing a polyvinyl alcohol resin or an ethylene-vinyl alcohol copolymer and an alkoxysilane by a sol-gel method is used as a film. Examples of coating are disclosed in Patent Documents 1 and 2.
[0005]
[Patent Document 1]
Japanese Patent No. 2556940 [Patent Document 2]
Japanese Patent No. 2880654 [0006]
[Problems to be solved by the invention]
However, the film described in each of the above patent documents may not always have sufficient gas barrier properties under high humidity.
[0007]
Therefore, an object of the present invention is to provide a gas barrier film having a significantly improved gas barrier property under high humidity.
[0008]
[Means for Solving the Problems]
The present invention provides a gas barrier composition containing at least one cross-linking agent selected from an epoxy compound and an aldehyde compound, a hydrolyzate of metal alkoxide and / or a condensate thereof, and a polyacrylamide on at least one surface of a substrate. By using the coated gas barrier film, the above-mentioned problems have been solved.
[0009]
Since polyacrylamide and the hydrolyzate of metal alkoxide and / or its condensate undergo polycondensation reaction, a dense structure in which an organic substance and an inorganic substance are combined is formed, and the gap is filled with a predetermined crosslinking agent. A very dense and strong film is formed. Furthermore, the predetermined cross-linking agent easily reacts with the hydrophilic group in the structure and quickly hydrophobizes them, so that the film has excellent hot water resistance. Furthermore, since the substrate adhesion is improved by the effect of polyacrylamide, a coated film that exhibits excellent oxygen gas barrier properties under high humidity conditions can be obtained.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below.
The gas barrier composition according to the present invention is a composition containing a predetermined crosslinking agent, a hydrolyzate of metal alkoxide and / or a condensate thereof, and polyacrylamide.
[0011]
The polyacrylamide refers to a homopolymer or copolymer of acrylamide, and includes nonionic, anionic, cationic and amphoteric ones. Of these, nonionic acrylamide homopolymers are particularly preferably used.
[0012]
Although the weight average molecular weight of the said polyacrylamide is not specifically limited, 500-15 million are preferable and 5000-10 million are more preferable. If it is less than 500, the gas barrier property of the finally obtained composition tends to be poor. On the other hand, when it is larger than 15 million, the viscosity of the aqueous solution tends to be too high.
[0013]
The said crosslinking agent means what can carry out a crosslinking reaction with the other component in the said gas-barrier composition, and means at least 1 type chosen from an epoxy compound and an aldehyde compound.
[0014]
Specific examples of the epoxy compound include ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, triethylene glycol diglycidyl ether, tetraethylene glycol diglycidyl ether, nonaethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, dipropylene glycol. Diglycidyl ether, tripropylidyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, diglycidyl ethers such as glycerol diglycidyl ether, triglycidyl ethers such as glycerol triglycidyl ether, Tetraglycidyl ethers such as pentaerythritol tetraglycidyl ether Such as Le acids, and the like.
[0015]
Specific examples of the aldehyde compound include glyoxal, malondialdehyde, succinaldehyde, glutaraldehyde, hexane dial, heptane dial, octane dial, nonane dial, decandial, dodecandial, 2,4-dimethylhexane dial. 5-methylheptane dial, 4-methyloctane dial, 2,5-dimethyloctane dial, 3,6-dimethyldecandial, orthophthalaldehyde and the like.
[0016]
When the predetermined crosslinking agent is added, the addition amount is not particularly limited, but it is preferably 0.1 × 10 ^{−3 to} 5 mol, based on 1 mol of amide group in polyacrylamide, and 0.5 × 10 ^{− 3 to} 3 moles are preferred. If the amount is less than 0.1 × 10 ⁻³ mol, the resulting layer made of the gas barrier composition lacks the density, and sufficient gas barrier properties tend to be hardly exhibited. On the other hand, when the amount is more than 5 mol, the solution tends to gel, or the performance of the obtained gas barrier film tends to deteriorate.
[0017]
The metal alkoxide refers to a compound represented by the following chemical formula (I).
M (OR) _n (I)
In the above formula (I), M represents at least one metal element selected from silicon, titanium, zirconium, aluminum and the like, R represents a lower alkyl group having 1 to 8 carbon atoms, and n represents 1 to 4 Indicates an integer.
[0018]
Since the metal alkoxide uses this hydrolyzate and / or its condensate, it is not particularly limited as long as it is hydrolyzed and condensed by the action of a catalyst. Examples of the metal alkoxide include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetra-n-propoxysilane, tetra-n-butoxysilane, tetra-tert-butoxysilane, and tetra-sec-butoxysilane. Alkoxysilane compounds, titanium alkoxide compounds such as tetramethoxy titanium, tetraethoxy titanium, tetraisopropoxy titanium, tetra-n-propoxy titanium, tetra-n-butoxy titanium, tetra-tert-butoxy titanium, tetra-sec-butoxy titanium, Tetramethoxyzirconium, tetraethoxyzirconium, tetraisopropoxyzirconium, tetra-n-propoxyzirconium, tetra-n-butoxyzirconium, tetra-tert-butoxy Zirconium alkoxide compounds such as ruthenium, tetra-sec-butoxyzirconium, trimethoxyaluminum, triethoxyaluminum, triisopropoxyaluminum, tri-n-propoxyaluminum, tri-n-butoxyaluminum, tri-tert-butoxyaluminum, tri- Examples thereof include aluminum alkoxide compounds such as sec-butoxyaluminum. Of these, alkoxysilane compounds are most preferred. At least one of these may be used, and only one may be used, or two or more may be used in combination.
[0019]
Although the usage-amount of the said metal alkoxide is not specifically limited, 50-5000 weight part is good with respect to 100 weight part of said polyacrylamide, and 1100-4000 weight part is preferable. When the amount is less than 50 parts by weight, sufficient gas barrier properties and hot water resistance tend to be hardly exhibited. On the other hand, when the amount is more than 5000 parts by weight, the brittleness of the resulting coating layer made of the gas barrier composition increases, and the performance tends to deteriorate.
[0020]
In order to perform the hydrolysis reaction or condensation reaction of the metal alkoxide, water, a catalyst for performing the hydrolysis reaction or condensation reaction, and an organic solvent are used. Furthermore, in order to further improve the bonding properties between the polyacrylamide and the hydrolyzate of metal alkoxide and / or its condensate, a silane compound having an organic functional group and a hydrolyzable group (hereinafter referred to as “specific silane compound”). .) May be added.
[0021]
The hydrolysis reaction of the metal alkoxide and the condensation reaction thereof, or the polycondensation reaction between the reaction product and the polyacrylamide are promoted under both acidic conditions and basic conditions. Examples of the catalyst under acidic conditions include mineral acids such as hydrochloric acid, nitric acid, and sulfuric acid, and organic acids such as phosphoric acid, acetic acid, citric acid, oxalic acid, and p-toluenesulfonic acid. In addition, catalysts under basic conditions include inorganic bases such as sodium hydroxide, calcium hydroxide, magnesium hydroxide, ammonia, pyridine, triethylamine, N, N-dimethylbenzylamine, tripropylamine, tributylamine, and tripentyl. And organic bases such as amines. Among these, acidic conditions are preferable, and hydrochloric acid is particularly preferable. Furthermore, these catalysts may use only 1 type and may use 2 or more types together. Furthermore, the catalyst may be divided into a catalyst for the hydrolysis reaction and a catalyst for the polycondensation reaction.
[0022]
The addition amount of said catalyst is not specifically limited, Arbitrary amounts can be added within the range in which a solution does not gel.
[0023]
The organic solvent is not particularly limited as long as it dissolves the metal alkoxide and is compatible with the polyacrylamide aqueous solution, but is preferably a lower alcohol such as methanol, ethanol, propanol, or butanol. These may use only 1 type and may use 2 or more types together.
[0024]
Although the addition amount of the organic solvent is not particularly limited, it is preferably 2 to 500 parts by weight and preferably 10 to 300 parts by weight with respect to 100 parts by weight of the metal alkoxide. When the amount is less than 2 parts by weight, the metal alkoxide is not sufficiently dissolved and the hydrolysis reaction is suppressed. On the other hand, when the amount is more than 500 parts by weight, the solubility of polyacrylamide tends to decrease.
[0025]
The gas barrier composition according to the present invention includes montmorillonite, vermiculite, swelling, in order to further improve the denseness of the gas barrier layer formed by applying the obtained gas barrier composition to at least one side of the substrate described later. Synthetic fluorine-based mica-based minerals can be added.
[0026]
The gas barrier composition may contain various additives such as a cross-linking agent, a dispersant, and a plasticizer, as necessary, as long as the performance of the finally obtained gas barrier film is not deteriorated.
[0027]
Next, the manufacturing method of the gas barrier composition concerning this invention is demonstrated. The gas barrier composition according to the present invention is produced by mixing the various raw materials described above. At this time, the metal alkoxide may be hydrolyzed in advance.
[0028]
The mixing order of the various raw materials is not particularly limited. However, when adding the metal alkoxide directly, first, an organic solvent and a catalyst are added to the polyacrylamide aqueous solution, and then the metal alkoxide and, if necessary, a specific silane. It is preferable to mix the compounds so that the solution is completely compatible, and then add a predetermined crosslinking agent and, if necessary, various other additives.
[0029]
A gas barrier film can be obtained by molding the gas barrier composition according to the present invention by a known method. The gas barrier film can also be produced by applying the gas barrier composition to at least one surface of the substrate.
[0030]
The base material may have any strength as a base material regardless of gas permeability, such as polyamide resin such as nylon 6, nylon 66, nylon 46, polyethylene terephthalate, polyethylene naphthalate, polybutylene. Examples thereof include a polymer resin film composed of at least one resin selected from polyester resins such as naphthalate, polyolefin resins such as polypropylene and polyethylene, and mixed resins thereof, and laminates of these polymer resin films. This polymer resin film may be an unstretched film or a stretched film.
[0031]
In addition, in order to improve adhesiveness, you may perform the well-known corona discharge process, a flame process, an ultraviolet-ray process, an anchor coating agent application | coating process, etc. on the surface of the said base material.
[0032]
Moreover, you may use the vapor deposition film etc. which formed the inorganic oxide vapor deposition layer on the surface of the said resin film as said base material. In this case, the gas barrier composition may be applied to the vapor deposition surface of the vapor deposition film.
[0033]
The coating is not particularly limited as long as it is a method for forming a layer composed of the gas barrier composition on the surface of the base material, and usual coating such as gravure coating, reverse roll coating, wire bar coating, die coating, etc. A coating method can be adopted. The coating may be performed before or after stretching the film.
[0034]
Drying of the gas barrier coating layer formed by applying the gas barrier composition to the substrate is not particularly limited, but can be performed at a temperature below the melting point and softening point of the substrate, and the crosslinking reaction is sufficiently performed. The temperature to be performed may be sufficient. Since the gas barrier composition of the present invention is very reactive, it does not require heat treatment at a temperature exceeding 120 ° C. for a long time for the crosslinking reaction. Drying and heat treatment at 120 ° C. or lower and for several seconds at a relatively low temperature and in a short time are sufficient.
[0035]
Furthermore, by aging the substrate coated with the gas barrier composition and dried, the crosslink density of the formed gas barrier coat layer can be increased, and the barrier property can be further improved. Although the temperature and time of this aging are not specifically limited, 1-150 hours are preferable at 20-120 degreeC, and 6-100 hours are more preferable at 30-70 degreeC.
[0036]
If the temperature is lower than 20 ° C., the aging time tends to be excessive, while if it exceeds 120 ° C., the substrate may be damaged. If the time is shorter than 1 hour, the crosslinking density may not be increased sufficiently. On the other hand, although it may exceed 150 hours, it has no effect on performance improvement.
[0037]
The gas barrier composition may have a porous structure if the organic substance and the inorganic substance are rapidly combined, for example, by an operation such as heating the solution, and sufficient performance may not be obtained. is there. For this reason, after making it apply | coat and dry to a base material and making it react gradually by operation, such as said aging, a more precise structure can be made.
[0038]
Since this gas barrier film has a gas barrier layer having a very dense structure, it exhibits a sufficient gas barrier property under high humidity conditions, and is excellent in surface smoothness and transparency.
[0039]
The barrier film according to the present invention is a high barrier film having very good gas barrier properties under high humidity, specifically at 23 ° C. and 90% RH. 23 ° C. per the gas barrier coat layer 1 [mu] m, an oxygen permeability at 90% RH ^{is, 1cc / m 2 · day ·} atm or less ^{well, 0.8cc / m 2 · day ·} atm or less. If it is greater than 1 cc / m ² · day · atm, the practicality of a high barrier packaging material is lacking.
[0040]
The gas barrier film according to the present invention can be used as it is as a gas barrier film, and at least one layer of this gas barrier film can be laminated on another film or sheet to form a laminate. This laminate can be used as a laminate having gas barrier properties.
[0041]
【Example】
The present invention will be described more specifically with reference to the following examples and comparative examples. First, the materials used and the evaluation methods are shown below.
[0042]
[Raw materials]
(Crosslinking agent)
Epoxy compound: manufactured by Nagase ChemteX Corporation: Denacol EX850 (diethylene glycol diglycidyl ether, hereinafter abbreviated as “epoxy”)
Aldehyde compound: manufactured by Nippon Synthetic Chemical Industry Co., Ltd .: Glyoxal (active ingredient 40%, hereinafter abbreviated as “aldehyde”)
[0043]
(Water-soluble polymer)
Polyacrylamide: Tokyo Chemical Industry Co., Ltd .: Reagent (10% aqueous solution, weight average molecular weight 700,000 to 1,000,000, hereinafter abbreviated as “PAM”)
Polyvinyl alcohol: manufactured by Kuraray Co., Ltd .: PVA117 (average polymerization degree 1700, hereinafter abbreviated as “PVA”)
[0044]
(Metal alkoxide)
Tetraethoxysilane: Tama Chemical Industries, Ltd .: normal ethyl silicate (hereinafter abbreviated as “TEOS”)
Tetrapropyl titanate: Matsumoto Pharmaceutical Co., Ltd .: ORGATICS TA-10 (hereinafter abbreviated as “TA-10”)
Tetrapropylzirconium: Matsumoto Pharmaceutical Co., Ltd .: Orgatics ZA-40 (hereinafter abbreviated as “ZA-40”)
[0045]
(Specific silane compounds)
-3-glycidoxypropyltrimethoxysilane ... Shin-Etsu Silicone Co., Ltd. product: KBM-403
[0046]
[Evaluation methods]
(Gas barrier properties of film) [Oxygen permeability]
The oxygen permeability in an atmosphere of 23 ° C. and 90% relative humidity was measured with an oxygen permeation tester (manufactured by Modern Control, OX-TRAN 2/20).
Since the gas barrier property of the film varies depending on the type and thickness of the base film and the thickness of the coating layer, the oxygen permeability per 1 μm of the gas barrier coating layer (P _samp1e ) (unit: cc · 1 μm / m) according to the following formula: ² · day · atm) was calculated.
1 / P _total = 1 / P _samp1e + 1 / P _base
P _total ; Measurement result P _base ; Oxygen permeability of base film P _samp1e ; Oxygen permeability of gas barrier coat layer
(Heat resistant water)
A film coated with the gas barrier composition was immersed in warm water at 80 ° C. for 30 minutes, and the weight loss of the gas barrier composition was measured. The residual ratio of weight was evaluated according to the following criteria.
A: Weight remaining rate 100%
○: Residual weight ratio of 80% or more and less than 100% ×: Residual weight ratio of less than 80%
(Examples 1-3)
After preparing 250 g of a 2 wt% polyacrylamide aqueous solution (solid content 5 g), and then adding 75 g of ethanol, an appropriate amount of the catalyst shown in Table 1 (also used as a polycondensation catalyst) was added, and then 75 g of metal alkoxide was added. Added. Next, when the liquid became uniform, 0.1 mol of the crosslinking agent shown in Table 1 was added to 1 mol of the amide group of polyacrylamide and stirred to obtain a gas barrier composition.
[0049]
The obtained gas barrier composition is applied to a corona-treated surface of a stretched polyester film (Toyobo Co., Ltd .: E5100, thickness 12 μm) as a base film so that the coating thickness after drying becomes 1 μm. Coated with. Thereafter, drying and heat treatment were performed in a hot air dryer at 100 ° C. for 5 minutes to obtain a gas barrier film. Said test and evaluation were performed using the obtained gas-barrier film. The results are shown in Table 1.
[0050]
(Comparative Example 1)
A gas barrier composition and a gas barrier film were obtained in the same manner as in Example 1 except that no crosslinking agent was added. Said test and evaluation were performed using the obtained gas-barrier film. The results are shown in Table 1.
[0051]
(Comparative Example 2)
A gas barrier film was obtained in the same manner as in Example 2 except that polyvinyl alcohol was used instead of polyacrylamide. Said test and evaluation were performed using the obtained gas-barrier film. The results are shown in Table 1.
[0052]
(Comparative Example 3)
After preparing 250 g of a 2 wt% aqueous solution of polyvinyl alcohol (solid content 5 g), and then adding 75 g of ethanol, an appropriate amount of hydrolysis catalyst shown in Table 1 was added, and then 75 g of metal alkoxide and the above specified 4 g of silane compound was added. Next, when the liquid becomes uniform, 0.1 g of N, N-dimethylbenzylamine (abbreviated as “DMBA” in Table 1) as a polycondensation catalyst is added and stirred, and the gas barrier composition Got. The obtained gas barrier composition was used in the same manner as in Example 1 to obtain a gas barrier film. Said test and evaluation were performed using the obtained gas-barrier film. The results are shown in Table 1.
[0053]
(Comparative Example 4)
A gas barrier film was obtained in the same manner as in Example 1 except that the metal alkoxide and the catalyst were not added. Said test and evaluation were performed using the obtained gas-barrier film. The results are shown in Table 1.
[0054]
[Table 1]

[0055]
【The invention's effect】
According to the present invention, polyacrylamide and a hydrolyzate of metal alkoxide and / or a condensate thereof undergo a polycondensation reaction, so that a dense structure in which an organic substance and an inorganic substance are combined is formed, and this gap is formed with a predetermined crosslinking agent. A film having a very dense and strong structure filled with crosslinks is formed. Furthermore, the predetermined cross-linking agent easily reacts with the hydrophilic group in the structure and quickly hydrophobizes them, so that the film has excellent hot water resistance. Furthermore, since the substrate adhesion is improved by the effect of polyacrylamide, a coated film that exhibits excellent oxygen gas barrier properties under high humidity conditions can be obtained.

Claims (4)

Containing at least one crosslinking agent selected from an epoxy compound and an aldehyde compound, a hydrolyzate of metal alkoxide and / or a condensate thereof, and polyacrylamide ;
The addition amount of the crosslinking agent is 0.1 × 10 ^{−3 to} 5 mol with respect to 1 mol of the amide group in the polyacrylamide ,
A gas barrier film obtained by applying a gas barrier composition in which the metal alkoxide is used in an amount of 50 to 5000 parts by weight to 100 parts by weight of the polyacrylamide on at least one surface of a polymer resin film. Containing at least one crosslinking agent selected from an epoxy compound and an aldehyde compound, a hydrolyzate of metal alkoxide and / or a condensate thereof, and polyacrylamide ;
The addition amount of the crosslinking agent is 0.1 × 10 ^{−3 to} 5 mol with respect to 1 mol of the amide group in the polyacrylamide ,
A gas barrier composition in which the metal alkoxide is used in an amount of 50 to 5000 parts by weight based on 100 parts by weight of the polyacrylamide is applied to the vapor deposition surface of a vapor deposition film provided with an inorganic oxide vapor deposition layer on a polymer resin film. Processed gas barrier film. The gas barrier film according to claim 1 or 2 , wherein the metal element constituting the metal alkoxide is at least one selected from silicon, aluminum, titanium, and zirconium. A gas barrier laminate in which at least one gas barrier film according to any one of claims 1 to 3 is laminated.