JPWO2009051158A1 - Extraction tube and manufacturing method thereof - Google Patents

Abstract

A squeezed tube that is a multilayer structure having a layer made of modified EVOH (C) and a layer made of resin (F) other than (C), wherein the modified EVOH (C) is unmodified EVOH (A) Is obtained by modification with an epoxy compound (B) having a double bond, and the amount of modification by the epoxy compound (B) is 0.1 to 10 mol% with respect to the monomer unit of EVOH (A). The squeezed tube is characterized in that at least a part of the modified EVOH (C) is crosslinked and the gel fraction is 3% by mass or more. As a result, elution of the crosslinking agent into the contents is suppressed, it is excellent in safety and is flexible, and the appearance is good even when subjected to heat sterilization, and the gas barrier property is extremely lowered even after heat sterilization. There are few squeezed tubes that are kept hygienic until they are opened.

Description

  The present invention relates to a squeezed tube that is flexible, has a good appearance even when subjected to a retort sterilization treatment or an autoclave sterilization treatment, and has extremely little deterioration in gas barrier properties even after a heat sterilization treatment. The squeezed tube of the present invention is suitable, for example, for filling and packaging contents including toothpaste, food, semi-solid high nutrition liquid food, cosmetics, pharmaceuticals, and other aromatic components. A spouted squeezed tube that is subjected to heat sterilization treatment such as retort sterilization treatment or autoclave sterilization treatment and maintains hygiene until it is opened.

  As development of materials used for packaging containers progresses, containers having characteristics that can withstand heat sterilization at a high temperature for a relatively long time, such as retort containers, are required, and many have been proposed. Among these, usually, a thermoplastic resin alone such as polypropylene and high-density polyethylene having high heat resistance, or an oxygen barrier layer such as ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as EVOH) or polyamide. In which an olefin resin layer such as polypropylene or high-density polypropylene is laminated on both sides is used. However, these tubes have a high elastic modulus and are not necessarily suitable materials for squeezed tubes that require flexibility. In the case of a multilayer structure, there is a drawback that delamination occurs after heat sterilization. .

  EVOH has an extremely small oxygen permeation amount compared to other plastics, and also has a small permeation amount of various gases and chemicals. Thus, EVOH is used for various applications such as agricultural chemicals / pharmaceutical containers and food packaging materials because of its excellent barrier properties and excellent oil resistance and chemical resistance. However, EVOH has problems such as whitening, deformation, and reduced barrier properties under high-temperature and high-humidity conditions such as retort sterilization and autoclave sterilization. There was room for.

  In order to solve the above problems, the present inventors have paid attention to a crosslinking technique aimed at modifying EVOH. Various techniques for crosslinking EVOH to maintain high gas barrier properties and improve heat resistance and hot water resistance have been studied. For example, Patent Document 1 describes that a compound having an epoxy group and an allyl group is blended in EVOH and then crosslinked by light or heat. Small and hardly cross-linked. This is presumably because the epoxy group hardly reacts with EVOH. Moreover, when manufacturing the said compound, since it is necessary to mix | blend a compound which has an epoxy group and an allyl group in large quantities, this remains, and it uses it for especially a foodstuff, a semi-solid high nutrition liquid food, a pharmaceutical, cosmetics, etc. In this case, there is a concern that it may become a sanitary problem.

  In Patent Document 2 and Patent Document 3, EVOH is added with at least one crosslinking agent and crosslinking aid selected from polyfunctional allyl compounds, polyfunctional (meth) acrylic compounds and polyhydric alcohols and metal oxides, However, there is also a concern about sanitary problems due to residual additives. In addition, the cross-linking agent gelled by reacting with EVOH at the stage of melt kneading, and there was a problem in industrial long-term operation during resin production.

  Patent Document 4 describes that EVOH is added with a compound having two or more allyl ether groups, irradiated with an electron beam, and cross-linked. However, this is also a sanitary problem because the additive remains. Conceivable.

  Patent Document 5 describes a method in which triallyl cyanurate and triallyl isocyanurate are used as a crosslinking agent, and these are melt-kneaded with EVOH and then irradiated with an electron beam to crosslink EVOH. When triallyl isocyanurate remains, particularly when used in food packaging containers, there are concerns about hygiene problems. Also. Triallyl cyanurate and triallyl isocyanurate gelled by reacting with EVOH at the stage of melt kneading, and there was a problem in long-term operation.

  Patent Document 6 describes a method in which an EVOH film is brought into contact with water to be in a water-containing state and is crosslinked by irradiation with an electron beam. However, in this method, there is a problem that it is necessary to immerse the film in water for a long time, and high-speed production is difficult.

  Patent Document 7 describes that flexibility is improved while keeping gas barrier properties as much as possible by modifying EVOH with a specific epoxy compound. However, there is a problem that the melting point is greatly lowered by modification, and as such, it is difficult to use in applications where heat resistance is required. Patent Document 8 describes a resin composition comprising modified EVOH described in Patent Document 7 and unmodified EVOH.

JP 63-8448 A JP-A-5-271498 JP-A-9-157421 JP-A-9-234833 Japanese Patent Laid-Open No. 62-252409 JP 56-49734 A WO02 / 092643 WO03 / 072653

  The present invention has been made to solve the above-mentioned problems, and since it contains almost no harmful cross-linking agent, elution of the cross-linking agent into the contents is suppressed, and is excellent in safety and flexibility. To provide a squeezed tube that has a good appearance even when subjected to retort sterilization or autoclave sterilization, and that has a very low deterioration in gas barrier properties even after such heat sterilization and maintains hygiene until it is opened. It is intended.

  That is, the present invention relates to a layer composed of a modified ethylene-vinyl alcohol copolymer (C) (hereinafter referred to as modified EVOH (C)) and a resin (F) other than the modified EVOH (C) (hereinafter simply referred to as resin ( F) is a squeeze tube which is a multilayer structure having a layer composed of a modified EVOH (C) is an unmodified ethylene-vinyl alcohol copolymer (A) (hereinafter referred to as an unmodified EVOH (A )) Is modified with an epoxy compound (B) having a double bond (hereinafter referred to as epoxy compound (B)), and the amount of modification by the epoxy compound (B) is unmodified. It is 0.1 to 10 mol% with respect to the monomer unit of EVOH (A), at least a part of the modified EVOH (C) is crosslinked, and the gel fraction thereof is 3% by mass or more. Characterize It is out of the tube.

  The present invention also includes a layer comprising a resin composition containing a modified EVOH (C) and an unmodified ethylene-vinyl alcohol copolymer (D) (hereinafter referred to as an unmodified EVOH (D)), and A squeezed tube which is a multilayer structure having a layer made of resin (F), and modified EVOH (C) is obtained by modifying unmodified EVOH (A) with epoxy compound (B) The amount of modification by the epoxy compound (B) is 0.1 to 10 mol% based on the monomer unit of the unmodified EVOH (A), and at least a part of the modified EVOH (C) is crosslinked, and The extraction tube is characterized in that its gel fraction is 3% by mass or more.

  In the squeezed tube, the ethylene content of the unmodified EVOH (A) is preferably 5 to 55 mol%, and the saponification degree is preferably 90 mol% or more. It is also preferable that the epoxy compound (B) is a monovalent epoxy compound having a molecular weight of 500 or less, particularly allyl glycidyl ether. A preferred embodiment of the extraction tube is an extraction tube for retort sterilization. Among them, a spouted extraction tube is particularly suitable.

  A preferred embodiment of the present invention is a package formed by filling a squeeze tube with contents, and the package is characterized by being heat-sterilized before or after filling the contents. is there. At this time, it is preferable that the heat sterilization process is a retort sterilization process or an autoclave sterilization process.

  Further, the present invention is a method for producing a squeezed tube which is a multilayer structure having a layer made of modified EVOH (C) and a layer made of resin (F) other than the modified EVOH (C), EVOH (A) is modified with epoxy compound (B) to produce modified EVOH (C), a multilayer tube is formed using modified EVOH (C) and resin (F), and modified EVOH (C) A method for producing a squeezed tube, characterized in that at least a part thereof is crosslinked and the gel fraction is 3% by mass or more.

  Furthermore, the present invention provides a multilayer structure having a layer comprising a resin composition containing a modified EVOH (C) and an unmodified EVOH (D), and a layer comprising a resin (F) other than the modified EVOH (C). The modified EVOH (A) is modified with the epoxy compound (B) to produce a modified EVOH (C), and the modified EVOH (C) and the unmodified EVOH. (D) is mixed to produce a resin composition, a multilayer tube is formed using the resin composition and the resin (F), at least a part of the resin composition is crosslinked, and the gel content thereof It is a manufacturing method of the extraction tube characterized by making a rate into 3 mass% or more.

  In the method for producing a squeezed tube, modified EVOH (C) or modified EVOH (by irradiation with at least one selected from the group consisting of electron beam, X-ray, γ-ray, ultraviolet ray and visible ray, or heating. It is preferable to crosslink at least a part of the resin composition containing C).

  Since the squeezed tube of the present invention contains almost no harmful cross-linking agent, elution of the cross-linking agent into the contents is suppressed, and it is excellent in safety and flexibility, and is subjected to retort sterilization treatment and autoclave sterilization treatment. Even after that, the appearance is good, and even after such heat sterilization treatment, the gas barrier property is hardly lowered, and hygiene is maintained.

  The modified EVOH (C) used in the present invention is obtained by reacting an epoxy compound (B) having a double bond with the hydroxyl group of unmodified EVOH (A).

  The ethylene content of the unmodified EVOH (A) used in the present invention is preferably 5 to 55 mol%, more preferably 20 to 55 mol%, still more preferably 25 to 50 mol%. When the ethylene content is less than 5 mol%, the water resistance is poor, and when it is greater than 60 mol%, the gas barrier property is inferior. The ethylene content of the resulting modified EVOH (C) is the same as the ethylene content of the raw EVOH (A).

  The saponification degree of the unmodified EVOH (A) is preferably 90 mol% or more, preferably 98 mol% or more, and more preferably 99 mol% or more. When the saponification degree is less than 90 mol%, the gas barrier property and the thermal stability are inferior.

  Further, as will be described later, the modified EVOH (C) of the present invention is preferably obtained by allowing the unmodified EVOH (A) and the epoxy compound (B) to react in an extruder. In addition, unmodified EVOH (A) is exposed to heating conditions. At this time, if the unmodified EVOH (A) contains an excessive amount of an alkali metal salt and / or an alkaline earth metal salt, the resulting modified EVOH (C) may be colored. Moreover, problems, such as a viscosity fall of modified EVOH (C), arise and there exists a possibility that a moldability may fall. Moreover, when using a catalyst like the after-mentioned, in order to deactivate a catalyst, it is preferable that those addition amounts are as small as possible.

  In order to avoid the above problem, the alkali metal salt contained in the unmodified EVOH (A) is preferably 50 ppm or less in terms of metal element. In a more preferred embodiment, the alkali metal salt contained in the unmodified EVOH (A) is 30 ppm or less, more preferably 20 ppm or less in terms of metal element. Further, from the same viewpoint, the alkaline earth metal salt contained in the unmodified EVOH (A) is preferably 20 ppm or less, more preferably 10 ppm or less in terms of metal element, and 5 ppm or less. Is more preferable, and it is most preferable that the alkaline earth metal salt is not substantially contained in the unmodified EVOH (A).

  The preferred melt flow rate (MFR) (under 190 ° C. and 2160 g load) of the unmodified EVOH (A) used in the present invention is 0.1 to 100 g / 10 min, preferably 0.3 to 30 g / 10 minutes, more preferably 0.5 to 20 g / 10 minutes. However, those having a melting point near 190 ° C. or exceeding 190 ° C. were measured under a load of 2160 g and at a plurality of temperatures above the melting point, and in a semilogarithmic graph, the reciprocal absolute temperature was plotted on the horizontal axis, and the logarithm of MFR was plotted on the vertical axis. The value is extrapolated to 190 ° C. Two or more kinds of unmodified EVOH (A) having different MFRs can also be mixed and used.

  The epoxy compound (B) used in the present invention preferably has one epoxy group and one or more double bonds in the molecule. That is, it is preferably a monovalent epoxy compound. The molecular weight is preferably 500 or less. Those having a plurality of epoxy groups have a problem of crosslinking during modification. The type of double bond is particularly preferably a vinyl group which is a monosubstituted olefin, and next preferably a vinylene group or a vinylidene group which is a disubstituted olefin. Next preferred are trisubstituted olefins. Tetrasubstituted olefins are not suitable for the purposes of the present invention due to poor reactivity.

  Moreover, what can remove easily what was added excessively from EVOH as an epoxy compound (B) is preferable. As the removal method, it is practical to volatilize and remove from the vent of the extruder. Therefore, the boiling point is preferably 250 ° C. or less, and more preferably 200 ° C. or less. Moreover, it is preferable that carbon number of an epoxy compound (B) is 4-10. Specific examples of such an epoxy compound having a double bond include 1,2-epoxy-3-butene, 1,2-epoxy-4-pentene, 1,2-epoxy-5-hexene, 1,2- Examples include epoxy-4-vinylcyclohexane, allyl glycidyl ether, methallyl glycidyl ether, and ethylene glycol allyl glycidyl ether, and particularly preferably allyl glycidyl ether. Moreover, it is also possible to wash and remove from the vent of an extruder, and it is also preferable in this case that an epoxy compound (B) is soluble in water.

  The reaction conditions of the epoxy compound (B) and the unmodified EVOH (A) are not particularly limited, but in the same manner as described in WO02 / 092643 (Patent Document 7), the unmodified EVOH (A ) Is preferably reacted with the epoxy compound (B). At this time, it is preferable to add a catalyst. In that case, it is preferable to add a carboxylate as a deactivator after the reaction. In the extruder, it is preferable to add the epoxy compound (B) to the molten unmodified EVOH (A) because it is possible to prevent the volatilization of the epoxy compound (B) and to easily control the reaction amount. Excess epoxy compound (B) can be removed from the vent of the extruder. Furthermore, by washing the obtained pellets with warm water, the remaining epoxy compound (B) can be removed and at the same time, the remaining catalyst can be removed.

  The catalyst used in the present invention preferably contains a metal ion belonging to Groups 3-12 of the periodic table. The most important thing as a metal ion used for a catalyst is having moderate Lewis acidity. From this point, ions of metals belonging to Groups 3 to 12 of the periodic table are used. Among these, ions of metals belonging to Group 3 or Group 12 of the periodic table are preferable because they have appropriate Lewis acidity, and ions of zinc, yttrium, and gadolinium are more preferable. Among them, a catalyst containing zinc ions is optimal because it has an extremely high catalytic activity and the thermal stability of the resulting modified EVOH (C) is excellent.

  The addition amount of metal ions belonging to Groups 3 to 12 of the periodic table is preferably 0.1 to 20 μmol / g in terms of moles of metal ions with respect to the weight of unmodified EVOH (A). When it is too much, unmodified EVOH (A) may be gelled during melt-kneading, and is more preferably 10 μmol / g or less. On the other hand, if the amount is too small, the effect of adding the catalyst may not be sufficiently achieved, and the amount is more preferably 0.5 μmol / g or more. In addition, since the suitable addition amount of the ion of the metal which belongs to periodic table group 3-12 changes also with the kind of metal to be used and the kind of below-mentioned anion, it adjusts suitably also considering those points. Is done.

  The anion species of the catalyst containing a metal ion belonging to Groups 3 to 12 of the periodic table is not particularly limited, but it is preferable that the conjugate acid contains a monovalent anion which is a strong acid equal to or higher than sulfuric acid. This is because an anion in which the conjugate acid is a strong acid usually has a low nucleophilicity, so that it is difficult to react with the epoxy compound, and anion species are consumed by the nucleophilic reaction to prevent loss of catalytic activity. Further, by having such an anion as a counter ion, the Lewis acidity of the catalyst is improved and the catalytic activity is improved.

Monovalent anions in which the conjugate acid is a strong acid equivalent to or higher than sulfuric acid include sulfonate ions such as methanesulfonate ion, ethanesulfonate ion, trifluoromethanesulfonate ion, benzenesulfonate ion, toluenesulfonate ion; chlorine Halogen ions such as ions, bromine ions and iodine ions; perchlorate ions; tetrafluoroborate ions (BF ₄ ⁻ ), hexafluorophosphate ions (PF ₆ ⁻ ), hexafluoroarsinate ions (AsF ₆ ⁻ ), hexafluoro Anions having four or more fluorine atoms such as antimonate ions; tetraphenylborate derivative ions such as tetrakis (pentafluorophenyl) borate ions; tetrakis (3,5-bis (trifluoromethyl) phenyl) borate, bis (c Deca-7,8-dicarbaundecaborate deca borate) cobalt (III) ion, bis (undecamethylene 7,8-dicarbaundecaborate deca borate) iron (III) carborane derivative ions of the ion and the like. Of these, sulfonate ions are preferable, and trifluoromethanesulfonate ions are particularly preferable.

  As described above, the catalyst used in the present invention preferably contains a monovalent anion whose conjugate acid is a strong acid equal to or higher than sulfuric acid, but all anionic species in the catalyst are the same anion. It need not be a seed. Rather, it is preferable that the conjugate acid simultaneously contains an anion which is a weak acid.

  Examples of anions in which the conjugate acid is a weak acid include alkyl anions, aryl anions, alkoxides, aryloxy anions, carboxylates, and acetylacetonates and derivatives thereof. Of these, alkoxide, carboxylate, acetylacetonate and derivatives thereof are preferably used.

  It is preferable that the number of moles of an anion in which the conjugate acid is a strong acid equal to or higher than that of sulfuric acid is 0.2 to 1.5 times the number of moles of metal ions in the catalyst. When the molar ratio is less than 0.2 times, the catalytic activity may be insufficient, more preferably 0.3 times or more, and even more preferably 0.4 times or more. On the other hand, when the molar ratio exceeds 1.5 times, the modified EVOH (C) may be gelled, and is more preferably 1.2 times or less. The molar ratio is optimally 1 time. In addition, when the raw material unmodified EVOH (A) contains an alkali metal salt such as sodium acetate, the amount of the anion whose conjugate acid is a strong acid equal to or higher than that of sulfuric acid is consumed as much as it is neutralized. You can increase the number.

  The method for preparing the catalyst is not particularly limited. As a preferred method, a metal compound belonging to Groups 3 to 12 of the periodic table is dissolved or dispersed in a solvent, and the resulting solution or suspension is mixed with a conjugate acid in sulfuric acid. And a method of adding a strong acid such as sulfonic acid equivalent to or better than the above. Examples of the metal compound belonging to Group 3-12 of the periodic table used as a raw material include alkyl metals, aryl metals, metal alkoxides, metal aryloxides, metal carboxylates, metal acetylacetonates and the like. Here, when adding a strong acid to the solution or suspension of such a metal compound, it is preferable to add little by little. The solution containing the catalyst thus obtained can be introduced directly into the extruder.

  As the solvent for dissolving or dispersing the above-described metal compound, an organic solvent, particularly an ether solvent is preferable. This is because it hardly reacts even at the temperature in the extruder and the solubility of the metal compound is good. Examples of ether solvents include dimethyl ether, diethyl ether, tetrahydrofuran, dioxane, 1,2-dimethoxyethane, diethoxyethane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, and the like. As the solvent to be used, a solvent that is excellent in solubility of the metal compound, has a relatively low boiling point, and can be almost completely removed by the vent of the extruder is preferable. In that respect, diethylene glycol dimethyl ether, 1,2-dimethoxyethane and tetrahydrofuran are particularly preferred.

  In the above-described catalyst preparation method, instead of the strong acid to be added, an ester of a strong acid such as a sulfonic acid ester may be used. Since esters of strong acids are usually less reactive than strong acids themselves, they may not react with metal compounds at room temperature, but they are active in an extruder when placed in a high-temperature extruder maintained at around 200 ° C. A catalyst can be produced.

  As a method for preparing the catalyst, another method described below can be adopted. First, an aqueous catalyst solution is prepared by mixing a water-soluble metal compound and a strong acid such as sulfonic acid having a conjugate acid equivalent to or higher than sulfuric acid in an aqueous solution. At this time, the aqueous solution may contain an appropriate amount of alcohol. The obtained catalyst aqueous solution is brought into contact with unmodified EVOH (A), and then dried to obtain unmodified EVOH (A) containing the catalyst. Specifically, a method of immersing unmodified EVOH (A) pellets, particularly porous hydrous pellets, in the catalyst aqueous solution is preferable. In this case, the dry pellets thus obtained can be introduced into an extruder.

  The catalyst deactivator used is not particularly limited as long as it reduces the function of the catalyst as a Lewis acid. Alkali metal salts are preferably used. In order to deactivate a catalyst containing a monovalent anion whose conjugate acid is a strong acid equal to or higher than sulfuric acid, it is necessary to use an alkali metal salt of an anion of an acid weaker than the conjugate acid of the anion. By doing so, the counter ion of the metal ion belonging to Groups 3 to 12 of the periodic table constituting the catalyst is exchanged with a weak acid anion, and as a result, the Lewis acidity of the catalyst is lowered. The cation species of the alkali metal salt used for the catalyst deactivator is not particularly limited, and sodium salt, potassium salt and lithium salt are preferred as examples. Also, the anionic species is not particularly limited, and carboxylates, phosphates and phosphonates are exemplified as suitable ones.

  The use of a salt such as sodium acetate or dipotassium monohydrogen phosphate as the catalyst deactivator can significantly improve the thermal stability, but it may still be insufficient depending on the application. This is because metal ions belonging to Groups 3 to 12 of the Periodic Table still have some activity as a Lewis acid and thus act as a catalyst for the decomposition and gelation of the modified EVOH (C). it is conceivable that. As a method for further improving this point, it is preferable to add a chelating agent that strongly coordinates to ions of metals belonging to Groups 3 to 12 of the periodic table. As a result of such a chelating agent being able to strongly coordinate to the ions of the metal, the Lewis acidity can be almost completely lost, and a modified EVOH (C) excellent in thermal stability can be provided. Moreover, the strong acid which is the conjugate acid of the anion contained in a catalyst can also be neutralized as mentioned above by the said chelating agent being an alkali metal salt.

  Suitable chelating agents used as catalyst deactivators include oxycarboxylates, aminocarboxylates, aminophosphonates and the like. Specifically, examples of the oxycarboxylate include disodium citrate, disodium tartrate, and disodium malate. Aminocarboxylates include nitrilotriacetic acid trisodium, ethylenediaminetetraacetic acid disodium, ethylenediaminetetraacetic acid trisodium, ethylenediaminetetraacetic acid tripotassium, diethylenetriaminepentaacetic acid trisodium, 1,2-cyclohexanediamine tetraacetic acid trisodium, ethylenediamine diacetate. Illustrative examples include monosodium acetate and monosodium N- (hydroxyethyl) iminodiacetic acid. Examples of aminophosphonates include nitrilotrismethylenephosphonic acid hexasodium, ethylenediaminetetra (methylenephosphonic acid) octasodium, and the like. Of these, polyaminopolycarboxylic acid is preferred, and an alkali metal salt of ethylenediaminetetraacetic acid is most preferred in terms of performance and cost.

  The addition amount of the catalyst deactivator is not particularly limited and is appropriately adjusted according to the type of metal ion contained in the catalyst, the number of coordination sites of the chelating agent, etc., but the catalyst with respect to the number of moles of metal ions contained in the catalyst It is preferable that the molar ratio of the deactivator is 0.2 to 10. When the ratio is less than 0.2, the catalyst may not be sufficiently deactivated, more preferably 0.5 or more, and even more preferably 1 or more. On the other hand, if the ratio exceeds 10, the resulting modified EVOH (C) may be colored and the production cost may increase, more preferably 5 or less, and even more preferably 3 or less. It is.

  The method for introducing the catalyst deactivator into the extruder is not particularly limited. However, in order to uniformly disperse the catalyst deactivator, it is preferably introduced as a solution of the catalyst deactivator with respect to the molten modified EVOH (C). In consideration of the solubility of the catalyst deactivator and the influence on the surrounding environment, it is preferably added as an aqueous solution.

  The catalyst deactivator may be added to the extruder after melt-kneading unmodified EVOH (A) and epoxy compound (B) in the presence of the catalyst. However, it is preferable to add the catalyst deactivator after melt-kneading EVOH (A) and the epoxy compound (B) in the presence of a catalyst to remove the unreacted epoxy compound (B). As described above, when the catalyst deactivator is added as an aqueous solution, the catalyst deactivator is added before removing the unreacted epoxy compound (B). This is because water mixes in the epoxy compound (B), and the separation operation takes time. In addition, it is also preferable to remove moisture by a vent or the like after adding the aqueous solution of the catalyst deactivator.

  In the production method of modified EVOH (C), when a catalyst deactivator is used, a suitable production process includes (1) a melting step of unmodified EVOH (A); (2) epoxy compound (B) and catalyst (3) Step of removing unreacted epoxy compound (B); (4) Step of adding catalyst deactivator aqueous solution; (5) Step of removing moisture under reduced pressure Is done.

  From the viewpoint of carrying out the reaction smoothly, it is preferable to remove moisture and oxygen from the system. For this reason, you may remove a water | moisture content and oxygen using a vent etc. before adding an epoxy compound (B) in an extruder.

  The modification amount of the modified EVOH (C) by the epoxy compound (B) is in the range of 0.1 to 10 mol% with respect to the monomer unit of the unmodified EVOH (A), more preferably from 0.3 to It is in the range of 5 mol%, more preferably in the range of 0.5 to 3 mol%. When the amount of modification is 0.1 mol% or less, the effect of modification is small, and when it exceeds 10 mol%, there is a drawback that gas barrier properties and thermal stability are lowered.

  The preferred melt flow rate (MFR) of the modified EVOH (C) (190 ° C. under 2160 g load) is 0.1 to 100 g / 10 min, preferably 0.3 to 30 g / 10 min, more preferably 0.5 to 20 g / 10 min. However, those having a melting point near 190 ° C. or exceeding 190 ° C. were measured under a load of 2160 g and at a plurality of temperatures above the melting point, and in a semilogarithmic graph, the reciprocal absolute temperature was plotted on the horizontal axis, and the logarithm of MFR was plotted on the vertical axis. The value is extrapolated to 190 ° C.

  Using the modified EVOH (C) thus obtained, the squeezed tube of the present invention, which is a multilayer structure having a layer composed of the modified EVOH (C) and a layer composed of the resin (F), is produced. At this time, the modified EVOH (C) may contain a resin other than the modified EVOH (C) and various additives. Among these, a particularly preferred embodiment of the squeezed tube of the present invention is a layer made of a resin composition in which unmodified EVOH (D) is blended with modified EVOH (C). In general, the production cost of the modified EVOH (C) is higher than that of the unmodified EVOH (D). Therefore, the modified EVOH (C) having a high double bond concentration and the unmodified EVOH (D) are mixed to obtain a desired two-component solution. It is economical to produce a resin composition having a heavy bond concentration. Since the modified EVOH (C) having a large modification amount can be easily produced by reacting in the extruder by the method as described above, such a resin composition can be easily obtained. It is also easy to adjust the double bond concentration of the resin composition according to the application. As the unmodified EVOH (D), the same as the unmodified EVOH (A) described above can be used.

  The blending mass ratio (C / D) in the resin composition containing the modified EVOH (C) and the unmodified EVOH (D) is not particularly limited. In order to obtain a squeezed tube excellent in hot water resistance by setting the double bond concentration of the resin composition in a desired range, the lower limit of the ratio (C / D) is preferably 2/98. Is more preferably 15/85 or more, and particularly preferably 20/80 or more. On the other hand, from the viewpoint of production cost and barrier properties, the upper limit of the ratio (C / D) is preferably 60/40, and more preferably 40/60.

  The method of blending the modified EVOH (C) and the unmodified EVOH (D) is not particularly limited. You may mix | blend by melt-kneading, and you may mix | blend in a solution. From the viewpoint of productivity, melt kneading is preferred, and for example, melt kneading using pellets of modified EVOH (C) and unmodified EVOH (D) is a preferred embodiment.

  In the resin composition containing the modified EVOH (C) and the unmodified EVOH (D), the amount of modification by the epoxy compound (B) is the monomer unit of the unmodified EVOH (A) and the unmodified EVOH (D). Preferably it is the range of 0.1-10 mol% with respect to the total amount of a monomer unit, More preferably, it is the range of 0.3-5 mol%, More preferably, it is 0.5-3 mol% % Range.

  Various additives may be added to the resin composition containing the modified EVOH (C) or the modified EVOH (C) and the unmodified EVOH (D) as necessary. Examples of such additives include sensitizers, curing agents, curing accelerators, antioxidants, plasticizers, ultraviolet absorbers, antistatic agents, colorants, fillers, or other polymer compounds. These can be blended as long as the effects of the present invention are not inhibited. Specific examples of the additive include the following.

  Sensitizer: benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzyl diphenyl disulfide, tetramethyl thiuram monosulfide, azobisbutyronitrile, dibenzyl, diacetyl, acetophenone, 2,2-diethoxyacetophenone, benzophenone, 2-chlorothioxanthone, 2-methylthioxanthone and the like.

  Curing agents: methyl ethyl ketone peroxide, cyclohexane peroxide, cumene peroxide, benzoyl peroxide, dicumyl peroxide, t-butyl perbenzoate, and the like.

  Curing accelerator: metal soap such as cobalt 2-ethylhexanoate, cobalt naphthenate, manganese 2-ethylhexanoate, manganese naphthenate, methylaniline, dimethylaniline, diethylaniline, methyl-p-toluidine, dimethyl-p- Amines such as toluidine, methyl-2-hydroxyethylaniline, di-2-hydroxyethyl-p-toluidine or salts thereof such as hydrochloric acid, acetic acid, sulfuric acid and phosphoric acid;

  Antioxidant: 2,5-dibutyl-t-butylhydroquinone, 2,6-di-t-butyl-p-cresol, 4,4′-thiobis- (6-t-butylphenol), 2,2′-methylene -Bis- (4-methyl-6-butylphenol), octadecyl-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate, 4,4'-thiobis- (6-t- Butylphenol) and the like.

  Plasticizer: dimethyl phthalate, diethyl phthalate, dibutyl phthalate, wax, liquid paraffin, phosphate ester, etc.

  UV absorber: ethylene-2-cyano-3,3′-diphenyl acrylate, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3′-t-butyl-) 5'-methylphenyl) 5-chlorotriazole, 2-hydroxy-4-methoxybenzophenone, (2,2'-dihydroxy-4-methoxybenzophenone) and the like.

  Antistatic agents: pentaerythritol monostearate, sorbitan monopalmitate, sulfated oleic acid, polyethylene oxide, carbowax and the like.

  Colorant: carbon black, phthalocyanine, quinacridone, azo pigment, titanium oxide, bengara, etc.

  Filler: Glass fiber, mica, celite, calcium silicate, aluminum silicate, calcium carbonate, silicon oxide, montmorillonite, etc.

  Other polymer compounds: polyolefins such as ethylene-butene copolymers and ethylene-propylene copolymers; modified polyolefins modified with functional groups such as carboxyl groups; polyamides, polyesters, polystyrenes, polyvinylidene chloride, polyvinyl chloride, etc. .

  The squeezed tube of the present invention is obtained using the modified EVOH (C) to which an additive is added as necessary according to the above purpose. Hereinafter, this condition will be described.

  The squeeze tube of the present invention comprises a multilayer structure. Specifically, it is a squeezed tube made of a multilayer structure having a layer made of modified EVOH (C) and a layer made of resin (F) other than (C), or modified EVOH (C) and non-modified EVOH (C). A squeezed tube made of a multilayer structure having a layer made of a resin composition containing modified EVOH (D) and a layer made of a resin (F).

  The manufacturing method of the extraction tube which consists of such a multilayer structure is not specifically limited, You may melt-mold and you may laminate using an adhesive agent. In the case of melt molding, coextrusion molding, co-injection molding, extrusion coating, etc. are employed. In the case of melt molding, the modified EVOH (C) may be used as it is without adding additives, or the modified EVOH (C), unmodified EVOH (D) and various additives may be supplied to the extruder. Alternatively, it may be molded as it is by melt-kneading. Further, it may be molded after being melt-kneaded and once pelletized, and a suitable means is adopted as appropriate. Although the molding temperature in melt molding varies depending on the melting point of the modified EVOH (C), the molten resin temperature is preferably about 120 ° C to 250 ° C.

  The resin (F) is preferably a thermoplastic resin. Examples thereof include at least one selected from the group consisting of polyolefin, polyamide, polyester, polystyrene, polyurethane, polyvinylidene chloride, polyvinyl chloride, polyacrylonitrile, polycarbonate, acrylic resin and polyvinyl ester. Examples of the polyolefin include low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ethylene-α-olefin (α-olefin having 3 to 20 carbon atoms) copolymer, ionomer, polypropylene, propylene ( Α-olefins having 4 to 20 carbon atoms) copolymers, polybutenes, polymethylpentenes or other olefins alone or copolymers, or these olefins alone or copolymers with unsaturated carboxylic acids or their anhydrides or esters. Examples include graft-modified ones. It is also preferable that the resin (F) is an elastomer.

  The layered structure of the squeezed tube of the present invention which is a multilayer structure is a modified EVOH (C) layer or a layer composed of a resin composition containing a modified EVOH (C) and an unmodified EVOH (D). C2,...), When the resin (F) layer is F (F1, F2,...), And the adhesive layer provided as necessary is Ad, not only a two-layer structure of C / F, C / F / C, F / C / F, F1 / F2 / C, F / C / F / C / F, C2 / C1 / F / C1 / C2, C / Ad / F, C / Ad / F / Arbitrary configurations such as C, F / Ad / C / Ad / F, and F / Ad / C / Ad / C / Ad / F are possible. Moreover, the resin which improves the adhesiveness of both resin may be mix | blended. Among these layer configurations, more specifically, the layer configuration of polyamide / C / polyamide / Ad / (unstretched) polypropylene or polyester / C / Ad / (unstretched) polypropylene is particularly suitable for the elderly in the medical field. It is preferably used as a spouted squeezed tube application of a semi-solid high nutrient liquid food for use, and a layer structure composed of polyamide / C / polyamide / Ad / unstretched polypropylene is particularly preferred.

  In the squeezed tube of the present invention, at least a part of the resin composition containing modified EVOH (C) or modified EVOH (C) and unmodified EVOH (D) is crosslinked, and the gel fraction is 3 mass. % Or more. The squeeze tube of the present invention is at least a part of a resin composition containing modified EVOH (C) or modified EVOH (C) and unmodified EVOH (D) in the multilayer structure obtained as described above. Can be produced by crosslinking. The above-mentioned multilayer structure before crosslinking can be crosslinked by leaving it in the air for a long time. Usually, the multilayer structure before crosslinking is subjected to electron beam, X-ray, γ-ray, ultraviolet ray and visible light. It is desirable to perform crosslinking by irradiating at least one selected from the group consisting of or heating. Irradiation can also be performed after filling the squeezed tube with contents, and at that time, two treatments, a sterilization treatment and a crosslinking treatment, can be performed simultaneously.

  When an electron beam, X-ray or γ-ray is used, the absorbed dose is preferably 1 kGy or more. More preferably, it is 1 kGy-1MGy, More preferably, it is 5 kGy-500 kGy, Especially preferably, it is 10 kGy-200 kGy. When the absorbed dose is greater than 1 MGy, EVOH is decomposed, which causes problems such as a decrease in strength and coloring, which is not preferable. On the other hand, when the absorbed dose is smaller than 1 kGy, the gel fraction is not improved and the desired performance such as hot water resistance cannot be obtained.

  Further, when the squeezed tube of the present invention is characterized by performing heat sterilization after filling the contents, as described above, it is difficult to cause whitening / deformation and deterioration of the barrier property due to improvement of hot water resistance. .

  After filling the multilayer structure with the contents, a squeezed tube having excellent storage stability can be obtained by heat sterilization, in particular, boil sterilization or retort sterilization. Here, the retort sterilization process refers to a process in which a sealed object is sterilized with hot water under heating and pressurization using a high-pressure kettle. Here, as processing conditions, it is 80-145 degreeC and 0.1-0.45 MPa normally, and is 30-90 minutes. For the retort sterilization treatment, various methods such as a recovery method, a replacement method, a steam method, a shower method, and a spray method are adopted. Immediately after performing the retort sterilization treatment, the squeezed tube of the present invention may become white and opaque, but after removing the water adhering to the surface of the squeezed tube, it is made transparent by leaving it for a while. In the case where desiccation and gas barrier properties are more reliably restored, it is preferable to dry with hot air at 40 to 150 ° C. for 1 to 120 minutes. Other heat sterilization methods include hot filling and autoclave sterilization. Here, hot filling means filling the contents at 85 ° C. or higher and sterilizing, and autoclave sterilization processing is to put a gas such as saturated water vapor or hydrogen gas inside the pressure device and heat under pressure. This refers to the process of sterilizing microorganisms.

  It is important that the squeezed tube thus obtained has an insoluble rate in the water-phenol mixed solvent, that is, a gel fraction of 3% by mass or more. When this insoluble rate is less than 3 mass%, effects, such as hot water resistance which this invention show | plays, become small. The insoluble rate is preferably 5% by mass, more preferably 10% by mass, and particularly preferably 20% by mass or more. Here, the insoluble rate of the water-phenol mixed solvent is the modified EVOH (C) layer taken out from the squeezed tube into 100 parts by mass of the mixed solvent of water (15% by mass) -phenol (85% by mass), or modified. The resin composition layer containing EVOH (C) and unmodified EVOH (D) is added in an amount of 1 part by mass, heated and dissolved at 60 ° C. for 12 hours, filtered, and the filtrate is evaporated to dryness. In this case, filtration is performed using a filter device (filter paper, filter cloth, membrane) that allows substantially 100% of the dissolved uncrosslinked EVOH to pass through. In addition, when a filler is contained in the squeezed tube of the present invention, the gel fraction is calculated by subtracting the weight of the residue remaining after heating the insoluble matter of the solvent at 500 ° C. for 1 hour.

  The squeezed tube obtained by the present invention is flexible, has a good appearance even when subjected to retort sterilization treatment or autoclave sterilization treatment, and has extremely little deterioration in gas barrier properties even after such heat sterilization treatment. Sex is also maintained. Taking advantage of these characteristics, the squeezed tube of the present invention is suitable, for example, for filling and packaging contents including toothpaste, food, semi-solid high nutrition liquid food, cosmetics, pharmaceuticals, and other fragrance components. In particular, it is useful as a spouted squeezed tube as a packaging material for semi-solid high-nutrition liquid foods that have recently started to be used as preserved foods in the medical and nursing care fields. A squeezed tube filled with such contents is preferably used because it maintains hygiene until it is opened after heat sterilization.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited at all by these Examples. The evaluation was performed by the following method.

[1] Ethylene content of EVOH and degree of modification of modified EVOH A sample used for measurement was pulverized, and low molecular weight components were extracted with acetone, followed by drying at 120 ° C. for 12 hours. This sample was subjected to ¹ H-NMR measurement using DMSO-d ₆ as a solvent (“JNM-GX-500 type” manufactured by JEOL Ltd.), and an epoxy compound having a double bond was reacted in the obtained spectrum. The area of the double bond methine peak (5.9 ppm) or the double bond methylene peak (5.2 ppm) of the modified EVOH and the ethylene moiety peak (1.4 ppm) corresponding to the EVOH monomer unit. Calculated from the ratio.

[2] Melt flow rate (MFR) of EVOH and modified EVOH
Using a melt indexer L260 (manufactured by Techno Seven Co., Ltd.), the resin flow rate (g / 10 min) was measured at a load of 2.16 kg and a temperature of 190 ° C.

[3] Elution amount of allyl glycidyl ether (hereinafter sometimes referred to as AGE; epoxy compound having a double bond) Allyl glycidyl ether (AGE): 0.02 g, solvent (methanol: chloroform = 50: 50): 20 ml Two standard solutions of 100 ml were prepared, and a calibration curve was prepared by gas chromatography (GC) under the following conditions. About 0.05 g of denatured EVOH used for measurement was precisely weighed into a 10 ml capacity vial, 1 ml of methanol was added and heated to 80 ° C. to dissolve. After cooling this solution to room temperature, 4 ml of chloroform was added little by little to precipitate a white precipitate. The solution portion and the precipitate were separated with a centrifuge, the solution portion was subjected to GC analysis, and the AGE elution amount was determined by the previous calibration curve.
GC apparatus Agilent Technologies 6890, column: DB-5 (J & W Scientific, capillary column, length 30 m, φ0.25 mm, film sickness 1.0 μm)
Measurement conditions Inj. Temp. 150 ° C., carrier gas: helium, column flow rate: 3.0 ml / min, 50 ° C. (2 min hold) → temperature rise at 20 ° C./min→200° C. (0.5 min hold)

[4] Bending resistance (ISO 178)
Using an autograph manufactured by Toyo Seiki Co., Ltd. as a measuring device, using the test pieces of 4 mm × 10 mm × 80 mm (thickness × width × length) obtained in Examples 6-7 and Comparative Examples 4-5, 23 ° C., The bending elastic modulus (MPa), bending strength (MPa), and maximum bending strain (%) were measured under the conditions of a test speed of 2 mm / min and a fulcrum distance of 64 mm at 50% RH.

[5] Evaluation of appearance after retort sterilization The appearance of the squeezed tube after retort sterilization at 120 ° C. for 90 minutes was evaluated as follows.
A: Whitening and delamination were not observed, and the appearance of the squeezed tube was good.
B: Whitening and severe delamination occurred.

Synthesis example 1
28 parts by mass of zinc acetylacetonate monohydrate was mixed with 957 parts by mass of 1,2-dimethoxyethane to obtain a mixed solution. While stirring, 15 parts by mass of trifluoromethanesulfonic acid was added to the obtained mixed solution to obtain a catalyst solution.

  A TEM-35BS extruder (37 mmφ, L / D = 52.5) manufactured by Toshiba Machine Co., Ltd. was used, and a screw, three vents, and three pressure inlets were installed. The resin feed port was cooled with water, the temperature of the screw rotation portion was set to 200 ° C., and the operation was performed at a screw rotation speed of 300 rpm. EVOH (ethylene content 32 mol%, MFR 6.0 g / 10 min, potassium content 8 ppm, phosphate group content 20 ppm, saponification degree 99 mol% or more) is charged at 20.0 kg / hr from the resin feed port. Allyl glycidyl ether (AGE) was added from the pressure inlet at a rate of 2.93 kg / hr, and the catalyst solution at a rate of 0.5 kg / hr. Sodium acetate 0.82% aqueous solution was added at a rate of 0.6 kg / hr from the second pressure inlet. Excess AGE was removed from the first vent under reduced pressure, water was added at a rate of 1 kg / hr from the third pressure inlet, and water and AGE were removed from the second and third vents under reduced pressure. As a result, a modified EVOH (EVOH-1) having an AGE modification amount of 1.7 mol%, an MFR of 2.0 g / 10 min, and a melting point of 166 ° C. was obtained. The amount of AGE eluted from the obtained EVOH-1 was measured according to [3] and found to be 0.62 μg / g.

Synthesis example 2
Ratio of 60/40 mass ratio of modified EVOH (EVOH-1) obtained in Synthesis Example 1 and unmodified EVOH (ethylene content 27 mol%, MFR 1.8 g / 10 min, saponification degree 99 mol% or more) Then, using a 25 mmφ twin screw extruder (LABO PLASTOMIL MODEL 15C300 manufactured by Toyo Seiki Co., Ltd.), the mixture was extruded and pelletized at 220 ° C. under the conditions of a screw rotation speed of 100 rpm and an extrusion resin amount of 4.5 kg / hour. Subsequently, it dried at 80 degreeC for 12 hours, and modified | denatured EVOH (EVOH-2) was obtained (allyl glycidyl ether modification amount after blending is 1.0 mol% in calculation). When the AGE elution amount from the obtained EVOH-2 was measured according to [3], it was 0.36 μg / g, and the elution amount was 0.5 μg / g or less.

Synthesis example 3
The ratio of the modified EVOH (EVOH-1) obtained in Synthesis Example 1 and the unmodified EVOH (ethylene content 27 mol%, MFR 1.7 g / 10 min, saponification degree 99 mol% or more) at a mass ratio of 30/70 To obtain modified EVOH (EVOH-3) in the same manner as in Synthesis Example 2 (the amount of AGE modification after blending was calculated to be 0.5 mol%, and the amount of AGE elution was 0.18 μg / g). Become).

Synthesis example 4
Ratio of 60/40 mass ratio of modified EVOH (EVOH-1) obtained in Synthesis Example 1 and unmodified EVOH (ethylene content 32 mol%, MFR 1.6 g / 10 min, saponification degree 99 mol% or more) Then, a modified EVOH (EVOH-4) was obtained in the same manner as in Synthesis Example 2 (the AGE modification amount after blending was 1.0 mol% in calculation, and the AGE elution amount was 0.37 μg / g). Become).

Synthesis example 5
Ratio of 30/70 mass ratio of modified EVOH (EVOH-1) obtained in Synthesis Example 1 and unmodified EVOH (ethylene content 32 mol%, MFR 1.6 g / 10 min, saponification degree 99 mol% or more) Then, modified EVOH (EVOH-5) was obtained in the same manner as in Synthesis Example 2 (the amount of AGE modification after blending was 0.5 mol% in calculation, and the amount of AGE elution was 0.18 μg / g). Become).

Example 1
(1) Modified EVOH (EVOH-2) obtained in Synthesis Example 2 and polyamide “1022FD12” (trade name, manufactured by Ube Industries, Ltd., hereinafter referred to as PA) are used as raw materials, and each is introduced into separate extruders. According to the conditions shown below, a PA / EVOH-2 / PA two-type three-layer multilayer film was produced by coextrusion molding. The thickness structure of the obtained multilayer film was 20/15/20 μm.

The configuration and operating conditions of the coextrusion molding machine are as follows.
Extruder 1 [PA]: Single-screw extruder “GT-32-A type” manufactured by Plastic Engineering Laboratory Co., Ltd., screw diameter: 32 mmφ, screw rotation speed: 62 rpm, cylinder set temperature: 2
40 ° C
Extruder 2 [modified EVOH]: single-screw extruder “Lab ME CO-NXT” manufactured by Toyo Seiki Seisakusho Co., Ltd., screw diameter: 20 mmφ, screw rotation speed: 18 rpm, cylinder set temperature: 220 ° C.
Die size: 300 mm, film take-up speed: 4 m / min, cooling roll temperature: 60 ° C.

(2) An unstretched polypropylene “RXC-18 # 60” (trade name, manufactured by Tosero Co., Ltd .; hereinafter simply abbreviated as CPP) is anchor anchor (Takelac A385 (trade name, Takeda Pharmaceutical Industries Ltd.): Takenate A50 (trade name, Takeda Pharmaceutical Company Limited): ethyl acetate = 24: 4: 53 (mass ratio)). The obtained laminate film was irradiated with an electron beam of 100 kGy (acceleration voltage 200 kV) from the side where the CPP was not laminated to crosslink EVOH-2. The oxygen transmission rate (OTR) of this multilayer film at 20 ° C. and 65% RH was measured and found to be 0.50 cc · 20 μm / m ² · day · atm. Further, at this time, using a mixed solvent having a water / phenol mass ratio (water / phenol) of 15/85, the content of the insoluble content of the film when subjected to a heat dissolution test at 60 ° C. for 12 hours, That is, the gel fraction was 90.2%.

Using this film, a cylindrical squeezed tube was formed using a blank plate in which a multilayer film was punched out, under a heat-bonding condition of 215 ° C., 3 seconds, and 3 kgf / cm ² . 30 ml of distilled water was added as the contents of the squeezed tube and heat sealed. The squeezed tube filled with distilled water was subjected to retort sterilization at 120 ° C. for 90 minutes. As a result, the appearance of the squeezed tube was not whitened or delaminated, and was good. As a result of measuring the oxygen transmission rate (OTR) of the squeezed tube after retort sterilization treatment at 20 ° C. and 65% RH, it was 0.51 cc · 20 μm / m ² · day · atm. The results obtained in the above (1) and (2) are summarized in Table 1.

Example 2
(1) A PA / EVOH-3 / PA two-type three-layer multilayer film was produced by coextrusion molding in the same manner as in Example 1 (1) except that EVOH-3 obtained in Synthesis Example 3 was used. . The thickness structure of the obtained multilayer film was 20/15/20 μm.

(2) In the same manner as in Example 1 (2), after laminating CPP on the multilayer film obtained in (1) above, EVOH-3 was crosslinked by irradiating an electron beam, and 30 ml of distilled water was enclosed. A squeezed tube was obtained. The multilayer film after electron beam irradiation before obtaining the extraction tube had an oxygen transmission rate (OTR) at 20 ° C. and 65% RH of 0.40 cc · 20 μm / m ² · day · atm. The gel fraction was 70.8%. As a result of the retort sterilization treatment of the squeezed tube at 120 ° C. for 90 minutes, the appearance of the squeezed tube was satisfactory without whitening or delamination. The oxygen permeation rate (OTR) of the squeezed tube after retort sterilization treatment at 20 ° C. and 65% RH was measured and found to be 0.40 cc · 20 μm / m ² · day · atm. The results obtained in the above (1) and (2) are summarized in Table 1.

Example 3
(1) A PA / EVOH-4 / PA two-type three-layer multilayer film was produced by coextrusion molding in the same manner as in Example 1 (1) except that EVOH-4 obtained in Synthesis Example 4 was used. . The thickness structure of the obtained multilayer film was 20/15/20 μm.

(2) In the same manner as in Example 1 (2), after laminating CPP on the multilayer film obtained in (1) above, EVOH-4 was crosslinked by irradiating with an electron beam, and 30 ml of distilled water was enclosed. A squeezed tube was obtained. The oxygen permeation amount (OTR) of the multilayer film after electron beam irradiation before obtaining the squeezed tube under 20 ° C. and 65% RH was 0.65 cc · 20 μm / m ² · day · atm. The gel fraction was 89.4%. As a result of the retort sterilization treatment of the squeezed tube at 120 ° C. for 90 minutes, the appearance of the squeezed tube was satisfactory without whitening or delamination. The oxygen permeation amount (OTR) of the squeezed tube after the retort sterilization treatment at 20 ° C. and 65% RH was measured and found to be 0.64 cc · 20 μm / m ² · day · atm. The results obtained in the above (1) and (2) are summarized in Table 1.

Example 4
(1) A PA / EVOH-5 / PA two-type three-layer multilayer film was produced by coextrusion molding in the same manner as in Example 1 (1) except that EVOH-5 obtained in Synthesis Example 5 was used. . The thickness structure of the obtained multilayer film was 20/15/20 μm.

(2) In the same manner as in Example 1 (2), after laminating CPP on the multilayer film obtained in (1) above, EVOH-5 was crosslinked by irradiating with an electron beam, and 30 ml of distilled water was enclosed. A squeezed tube was obtained. The oxygen permeation amount (OTR) of the multilayer film after electron beam irradiation before obtaining the squeezed tube under 20 ° C. and 65% RH was 0.55 cc · 20 μm / m ² · day · atm. The gel fraction was 68.1%. As a result of the retort sterilization treatment of the squeezed tube at 120 ° C. for 90 minutes, the appearance of the squeezed tube was satisfactory without whitening or delamination. As a result of measuring the oxygen transmission rate (OTR) of the squeezed tube after retort sterilization treatment at 20 ° C. and 65% RH, it was 0.56 cc · 20 μm / m ² · day · atm. The results obtained in the above (1) and (2) are summarized in Table 1.

Example 5
(1) In the same manner as in Example 1 (1), a PA / EVOH-2 / PA two-type three-layer multilayer film was produced by coextrusion molding. The thickness structure of the obtained multilayer film was 20/15/20 μm.

(2) A squeezed tube enclosing 30 ml of distilled water was obtained in the same manner as in Example 1 (2) except that the electron beam dose was 10 kGy (acceleration voltage 200 kV). The oxygen permeation amount (OTR) of the multilayer film after electron beam irradiation before obtaining the squeezed tube under 20 ° C. and 65% RH was 0.39 cc · 20 μm / m ² · day · atm. The gel fraction was 20.2%. As a result of the retort sterilization treatment of the squeezed tube at 120 ° C. for 90 minutes, the appearance of the squeezed tube was satisfactory without whitening or delamination. The oxygen permeation amount (OTR) of the squeezed tube after retort sterilization treatment at 20 ° C. and 65% RH was measured and found to be 0.38 cc · 20 μm / m ² · day · atm. The results obtained in the above (1) and (2) are summarized in Table 1.

Comparative Example 1
(1) “Eval” having an ethylene content of 27 mol% instead of modified EVOH (EVOH-2), MFR 4.0 g / 10 min (measured at 210 ° C. because of a melting point of 191 ° C.), and a saponification degree of 99 mol% or more A PA / “EVAL” L171B / PA two-type three-layer multilayer film was produced by coextrusion molding in the same manner as in Example 1 (1) except that L171B (trade name, manufactured by Kuraray Co., Ltd.) was used. The thickness structure of the obtained multilayer film was 20/15/20 μm.

(2) In the same manner as in Example 1 (2), after laminating CPP on the multilayer film obtained in (1) above, a squeezed tube filled with 30 ml of distilled water without irradiation with an electron beam was obtained. It was. Before the extraction tube was obtained, the oxygen non-irradiated multilayer film had an oxygen transmission rate (OTR) at 20 ° C. and 65% RH of 0.22 cc · 20 μm / m ² · day · atm. The gel fraction was 0%. As a result of the retort sterilization treatment of the squeezed tube at 120 ° C. for 90 minutes, the tube appearance was whitened and delamination was severely generated. The oxygen permeation amount (OTR) of the squeezed tube after retort sterilization under 20 ° C. and 65% RH could not be measured due to severe destruction of the tube. The results obtained in the above (1) and (2) are summarized in Table 1.

Comparative Example 2
(1) PA / EVOH-3 / PA two-type three-layer multilayer film in the same manner as in Example 1 (1) except that modified EVOH (EVOH-3) was used instead of modified EVOH (EVOH-2) Was produced by coextrusion. The thickness structure of the obtained multilayer film was 20/15/20 μm.

(2) In the same manner as in Example 1 (2), after laminating CPP on the multilayer film obtained in (1) above, the electron beam was not irradiated, that is, EVOH-3 was not subjected to crosslinking treatment, and distilled. A squeezed tube filled with 30 ml of water was obtained. Before the extraction tube was obtained, the oxygen non-irradiated multilayer film had an oxygen transmission rate (OTR) at 20 ° C. and 65% RH of 0.50 cc · 20 μm / m ² · day · atm. The gel fraction was 1.7%. As a result of the retort sterilization treatment of the squeezed tube at 120 ° C. for 90 minutes, the tube appearance was whitened and delamination was severely generated. The oxygen permeation amount (OTR) of the squeezed tube after the retort sterilization treatment under 20 ° C. and 65% RH could not be measured due to severe destruction of the tube. The results obtained in the above (1) and (2) are summarized in Table 1.

Comparative Example 3
(1) PA / EVOH-5 / PA two-type three-layer multilayer film in the same manner as in Example 1 (1) except that modified EVOH (EVOH-5) was used instead of modified EVOH (EVOH-2) Was produced by coextrusion. The thickness structure of the obtained multilayer film was 20/15/20 μm.

(2) In the same manner as in Example 1 (2), after the CPP was laminated on the multilayer film obtained in (1) above, the electron beam was not irradiated, that is, EVOH-5 was not subjected to crosslinking treatment, and distilled. A squeezed tube filled with 30 ml of water was obtained. Before the extraction tube was obtained, the oxygen non-irradiated multilayer film had an oxygen transmission rate (OTR) at 20 ° C. and 65% RH of 0.71 cc · 20 μm / m ² · day · atm. The gel fraction was 1.5%. As a result of the retort sterilization treatment of the squeezed tube at 120 ° C. for 90 minutes, the tube appearance was whitened and delamination was severely generated. The oxygen permeation amount (OTR) of the squeezed tube after retort sterilization under 20 ° C. and 65% RH could not be measured due to severe destruction of the tube. The results obtained in the above (1) and (2) are summarized in Table 1.

Example 6
The modified EVOH (EVOH-3) obtained in Synthesis Example 3 was used and introduced into an injection molding machine (manufactured by Toyo Seiki Co., Ltd.). A test piece of 10 mm × 80 mm (thickness × width × length) was obtained. The obtained test piece was irradiated with an electron beam of 30 kGy (acceleration voltage 200 kV) and crosslinked. At this time, the gel fraction was 34.1%. A notch (based on ISO2818) was put into the test piece after crosslinking with an electron beam with calipers, and the flex resistance was evaluated based on [4]. As a result of the measurement, the bending elastic modulus was 3340 MPa, the bending strength was 97 MPa, and it was confirmed that the flexibility was improved as compared with the conventional EVOH. The obtained results are summarized in Table 2.

Example 7
A cross-linked test piece of 4 mm × 10 mm × 80 mm (thickness × width × length) was obtained in the same manner as in Example 6 except that EVOH-5 obtained in Synthesis Example 5 was used. The obtained test piece was irradiated with an electron beam of 30 kGy (acceleration voltage 200 kV) for crosslinking. At this time, the gel fraction was 32.3%. As a result of measuring the bending resistance in the same manner as in Example 6, the bending elastic modulus was 3270 MPa, the bending strength was 95 MPa, and it was confirmed that the bending resistance was improved as compared with the conventional EVOH. The obtained results are summarized in Table 2.

Comparative Example 4
4 mm × 10 mm × 80 mm (thickness) in the same manner as in Example 6 except that “EVAL” L171B (trade name, manufactured by Kuraray Co., Ltd.) was used instead of modified EVOH (EVOH-3) and no electron beam was irradiated. A test piece of (six width x length) was obtained. At this time, the gel fraction was 0%. As a result of measuring the bending resistance in the same manner as in Example 6, the bending elastic modulus was 4080 MPa, and the bending strength was 119 MPa. The obtained results are summarized in Table 2.

Comparative Example 5
Instead of the modified EVOH (EVOH-3), an “Eval” F101B (trade name, manufactured by Kuraray Co., Ltd.) having an ethylene content of 32 mol%, MFR 1.6 g / 10 min, and a saponification degree of 99 mol% or more was used. A test piece of 4 mm × 10 mm × 80 mm (thickness × width × length) was obtained in the same manner as in Example 6 except that was not irradiated. At this time, the gel fraction was 0%. The bending resistance was measured in the same manner as in Example 6. As a result, the bending elastic modulus was 4080 MPa and the bending strength was 120 MPa. The obtained results are summarized in Table 2.

Claims (11)

  A squeezed tube which is a multilayer structure having a layer made of a modified ethylene-vinyl alcohol copolymer (C) and a layer made of a resin (F) other than the modified ethylene-vinyl alcohol copolymer (C). The modified ethylene-vinyl alcohol copolymer (C) was obtained by modifying an unmodified ethylene-vinyl alcohol copolymer (A) with an epoxy compound (B) having a double bond. The amount of modification by the epoxy compound (B) having a double bond is 0.1 to 10 mol% with respect to the monomer unit of the ethylene-vinyl alcohol copolymer (A), and the modified ethylene-vinyl alcohol system A squeezed tube, wherein at least a part of the copolymer (C) is crosslinked and the gel fraction thereof is 3% by mass or more.   A layer comprising a resin composition containing a modified ethylene-vinyl alcohol copolymer (C) and an unmodified ethylene-vinyl alcohol copolymer (D), and a modified ethylene-vinyl alcohol copolymer (C) A squeezed tube which is a multilayer structure having a layer made of a resin (F) other than the above, wherein the modified ethylene-vinyl alcohol copolymer (C) is an unmodified ethylene-vinyl alcohol copolymer (A ) Is modified with an epoxy compound (B) having a double bond, and the amount of modification by the epoxy compound (B) having a double bond is that of the ethylene-vinyl alcohol copolymer (A). 0.1 to 10 mol% with respect to the monomer unit, at least a part of the resin composition is crosslinked, and the gel fraction is 3% by mass or more Tube.   The squeezed tube according to claim 1 or 2, wherein the unmodified ethylene-vinyl alcohol copolymer (A) has an ethylene content of 5 to 55 mol% and a saponification degree of 90 mol% or more. .   The extraction tube according to any one of claims 1 to 3, wherein the epoxy compound (B) having a double bond is a monovalent epoxy compound having a molecular weight of 500 or less.   The extraction tube according to claim 4, wherein the epoxy compound (B) having a double bond is allyl glycidyl ether.   The extraction tube according to any one of claims 1 to 5, which is an extraction tube for retort sterilization treatment.   A package comprising the squeezed tube according to any one of claims 1 to 6 filled with contents, wherein the package is heat sterilized before or after filling the contents. .   The package according to claim 7, wherein the heat sterilization treatment is a retort sterilization treatment or an autoclave sterilization treatment.   Production of a squeezed tube which is a multilayer structure having a layer made of a modified ethylene-vinyl alcohol copolymer (C) and a layer made of a resin (F) other than the modified ethylene-vinyl alcohol copolymer (C) A modified ethylene-vinyl alcohol copolymer (C) is produced by modifying an unmodified ethylene-vinyl alcohol copolymer (A) with an epoxy compound (B) having a double bond. And forming a multilayer tube using the modified ethylene-vinyl alcohol copolymer (C) and the resin (F), crosslinking at least a part of the modified ethylene-vinyl alcohol copolymer (C), and And the manufacturing method of the extraction tube characterized by making the gel fraction into 3 mass% or more.   A layer comprising a resin composition containing a modified ethylene-vinyl alcohol copolymer (C) and an unmodified ethylene-vinyl alcohol copolymer (D), and a modified ethylene-vinyl alcohol copolymer (C) A method for producing a squeezed tube that is a multilayer structure having a layer made of a resin (F) other than the above, wherein an unmodified ethylene-vinyl alcohol copolymer (A) is converted into an epoxy compound ( B) to produce a modified ethylene-vinyl alcohol copolymer (C), a modified ethylene-vinyl alcohol copolymer (C) and an unmodified ethylene-vinyl alcohol copolymer (D). Is mixed to produce a resin composition, a multilayer tube is formed using the resin composition and the resin (F), at least a part of the resin composition is crosslinked, and the gel fraction thereof Method for producing a Shibode tubes characterized by a 3 mass% or more. At least one part selected from the group consisting of electron beam, X-ray, γ-ray, ultraviolet ray and visible ray is irradiated or heated to at least partially crosslink the modified ethylene-vinyl alcohol copolymer (C). The manufacturing method of the extraction tube of Claim 9 or 10.