JP2018053034A - Polyamide resin and gas-barrier multilayer molded body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyamide resin that can endure heat treatment and hot filling, is less likely to cause the discoloration during the production and secondary processing and has excellent transparency and gas barrier performance.SOLUTION: The polyamide resin is produced by polycondensation reaction of a diamine containing bis(aminomethyl)furan and a dicarboxylic acid containing an aliphatic dicarboxylic acid and an aromatic dicarboxylic acid in which the proportion of the bis(aminomethyl)furan in the diamine is 60 mol% or more; the proportion of the aliphatic dicarboxylic acid in the dicarboxylic acid is 70 mol% to 98 mol%; and the proportion of the aromatic dicarboxylic acid in the dicarboxylic acid is 2 mol% to 30 mol%.SELECTED DRAWING: None

Description

  The present invention relates to a polyamide resin having gas barrier properties and a molded product thereof.

As packaging materials for pharmaceuticals, beverages, foods, chemicals, etc., packaging containers and packaging films made of thermoplastic resins are used in the largest quantities due to their light weight, moldability, packaging productivity such as heat sealing, and cost. Has been. However, generally, packaging containers and packaging films made of a thermoplastic resin have a large gas permeation of oxygen or the like through the thermoplastic resin layer, and there is a problem in terms of storage stability of contents.
In order to prevent permeation of gas such as oxygen from the inside and outside of the molded body, a thermoplastic resin packaging container or packaging film has a multilayered wall and a gas barrier layer is used as at least one of them. Known resins used for this gas barrier layer include ethylene-vinyl alcohol copolymer resins, vinylidene chloride copolymer resins, acrylonitrile copolymer resins, and polyamide resins such as polymethaxylylene adipamide.

  Among these gas barrier resins, polyamide resins such as polymetaxylylene adipamide obtained by polycondensation of metaxylenediamine and adipic acid have excellent gas barrier properties, and other thermal stability during melting. Since it is better than other resins, it can be co-extruded or co-injected with various thermoplastic resins such as polyethylene terephthalate (PET), nylon 6 and polyolefin, and has recently been used as a gas barrier layer for multilayer structures. Are actively used.

  Furthermore, in Patent Document 1, the polyester resin having a flange carboxylate moiety in the polymer skeleton has an excellent gas barrier property against carbon dioxide gas, oxygen, etc., and can be applied to packaging films and beverage containers. Is disclosed.

  Patent Document 2 discloses that a polyamide can be synthesized from a diamine having a furan ring similar to the polyester resin and a dicarboxylic acid. However, for example, the glass transition point of polyamide obtained from the polycondensation reaction of bis (aminomethyl) furan and adipic acid is around 90 ° C. Assuming that the polyamide is used as a gas barrier layer of a multilayer structure with various thermoplastic resins in the same manner as the polymetaxylylene adipamide, for example, a multilayer structure with a polyolefin has a softening point of the polyolefin. Is higher than the glass transition point of the polyamide, and is easily crystallized during secondary processing. As a result, when secondary processing is performed in a state where crystallization has progressed, uneven thickness or whitening is observed, and there may be a case where a molded product that is satisfactory in terms of performance such as shape and transparency may not be obtained.

  Furthermore, since the thermoplastic resin is processed at a temperature equal to or higher than its melting point, for example, when a polyolefin and a polyamide having a high melting point are co-extruded to form a multilayer structure, a molten polyolefin resin layer and a polyamide resin layer are formed. Therefore, the polyolefin resin receives a severe heat history. In particular, when molding a multilayer structure with polypropylene, there are problems such as coloring and odor due to deterioration of the polypropylene resin.

Special table 2014-530948 gazette Special table 2014-524953 gazette

  An object of the present invention is to provide a polyamide resin which can withstand heat treatment and hot filling and has excellent transparency and gas barrier performance with little coloring during production and secondary processing.

  As a result of intensive studies, the present inventors have obtained a polyamide resin obtained from a polycondensation reaction between a diamine containing bis (aminomethyl) furan and a dicarboxylic acid containing an aliphatic dicarboxylic acid and an aromatic dicarboxylic acid. A polyamide resin in which the proportion of bis (aminomethyl) furan in the diamine and the proportion of aliphatic dicarboxylic acid and the proportion of aromatic dicarboxylic acid in the dicarboxylic acid are within specific ranges, respectively, solve the above problems As a result, the inventors have found out that the present invention can be achieved. Hereinafter, the present invention will be described.

  [1] A polyamide resin obtained from a polycondensation reaction between a diamine containing bis (aminomethyl) furan and a dicarboxylic acid containing an aliphatic dicarboxylic acid and an aromatic dicarboxylic acid, the bis (aminomethyl) in the diamine The proportion of furan is 60 mol% or more, the proportion of aliphatic dicarboxylic acid in the dicarboxylic acid is 70 mol% to 98 mol%, and the proportion of aromatic dicarboxylic acid is 2 mol% to 30 mol%. Polyamide resin.

  [2] The polyamide resin according to [1], wherein the aromatic dicarboxylic acid contains 50 mol% or more of isophthalic acid.

  [3] The polyamide resin according to [1] or [2], wherein the aliphatic dicarboxylic acid contains 80 mol% or more of a long-chain aliphatic dicarboxylic acid having 6 to 10 carbon atoms.

  [4] A gas barrier multilayer molded article formed by joining at least one gas barrier layer containing the polyamide resin according to any one of [1] to [3] and at least one layer containing another thermoplastic resin.

  According to the present invention, a polyamide resin having excellent transparency and gas barrier performance, which has a high glass transition point, can withstand heat treatment and hot filling, and has a relatively low melting point, is less colored during secondary processing. Can be provided.

The polyamide resin of the present invention is a polyamide resin obtained by a polycondensation reaction between a diamine containing bis (aminomethyl) furan and a dicarboxylic acid containing an aliphatic dicarboxylic acid and an aromatic dicarboxylic acid.
The polycondensation reaction for obtaining the polyamide resin may be a method in which a dicarboxylic acid and a diamine are passed through a nylon salt, or a method in which the dicarboxylic acid and the diamine are directly reacted in a molten state under normal pressure. Examples of the direct reaction include a diamine containing bis (aminomethyl) furan while raising the temperature to 160 to 300 ° C. to a molten dicarboxylic acid containing an aliphatic dicarboxylic acid in which a powdered aromatic dicarboxylic acid is dispersed. Can be added dropwise under normal pressure to cause a reaction. According to this direct reaction method, unlike the method using a nylon salt, a polyamide resin can be easily obtained without leaving a nylon salt from an aromatic dicarboxylic acid having a high melting point and bis (aminomethyl) furan in the reaction system. Can get to.

  The diamine as a raw material for the polyamide resin of the present invention contains bis (aminomethyl) furan as an essential component. The bis (aminomethyl) furan content in the diamine is preferably 60 mol% or more. When the content is less than 60 mol%, the gas barrier properties of the obtained polyamide resin may be lowered. The content of bis (aminomethyl) furan is preferably 70 mol% or more, and more preferably 80 mol% or more.

  The polyamide resin of the present invention may contain other diamines other than bis (aminomethyl) furan as the diamine. Examples of other diamines include aliphatic diamines such as tetramethylene diamine, pentamethylene diamine, hexamethylene diamine, and octamethylene diamine, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane. And aliphatic diamines having a cyclic structure such as metaxylylenediamine, paraxylylenediamine, metaphenylenediamine, and paraphenylenediamine.

The dicarboxylic acid as a raw material of the polyamide resin of the present invention contains an aliphatic dicarboxylic acid and an aromatic dicarboxylic acid as essential components, and the proportion of the aliphatic dicarboxylic acid in the dicarboxylic acid is within the range of 70 mol% to 98 mol%. The ratio of the aromatic dicarboxylic acid is in the range of 2 mol% to 30 mol%. By using aliphatic dicarboxylic acid and aromatic dicarboxylic acid in a predetermined ratio as dicarboxylic acid, the melting point of the resulting polyamide resin is lowered, and it can be molded at a lower temperature. Therefore, a high-quality multilayer without gel, odor or coloring It becomes possible to obtain a molded body. Further, since the crystallization speed of the resin is delayed, secondary workability such as deep drawing is improved.
The proportion of the aliphatic dicarboxylic acid is more preferably 75 mol% to 95 mol%, and further preferably 80 mol% to 95 mol%. The ratio of the aromatic dicarboxylic acid is more preferably 5 mol% to 25 mol%, and further preferably 5 mol% to 20 mol%.

  If the ratio of the aliphatic dicarboxylic acid exceeds 98 mol%, the melting point of the resulting polyamide resin increases and the molding temperature rises, so that gel, odor, and coloring may occur during secondary processing. If the ratio of the aliphatic dicarboxylic acid is less than 70 mol%, the resulting polyamide resin is hard and brittle, so that cracks and pinholes in the gas barrier layer may easily occur in the shape of the molded body.

  When the ratio of the aromatic dicarboxylic acid exceeds 30 mol%, the crystallization speed of the resulting polyamide resin is greatly delayed, so that the secondary processability is improved, but the melt viscosity is excessively increased and the melt viscosity is increased. Since the temperature dependency of the temperature increases, control during melt processing becomes difficult, and molding processability may be reduced. When the proportion of the aromatic dicarboxylic acid is less than 2 mol%, the obtained polyamide resin exhibits properties as a crystalline polymer, and is heated by secondary processing, hydrothermal treatment of the product obtained after the secondary processing, and the like. Since it becomes easy to whiten, there exists a possibility that heat resistance and transparency may deteriorate.

  The aromatic dicarboxylic acid used as a raw material for the polyamide resin of the present invention preferably contains 50 mol% or more of isophthalic acid. If the isophthalic acid content is less than 50 mol%, the resulting polyamide resin has a high melt viscosity, which may make melt molding difficult. The content of isophthalic acid is more preferably 70 mol% or more.

  The aromatic dicarboxylic acid may include other aromatic dicarboxylic acids other than isophthalic acid. Examples of other aromatic dicarboxylic acids include terephthalic acid, phthalic acid, naphthalenedicarboxylic acid, benzenediacetic acid, and the like.

  The aliphatic dicarboxylic acid used as a raw material for the polyamide resin of the present invention preferably contains 80 mol% or more of a long-chain aliphatic dicarboxylic acid having 6 to 10 carbon atoms. When the content of the long-chain aliphatic dicarboxylic acid is less than 80 mol%, the resulting polyamide resin may be brittle. The content of the long-chain aliphatic dicarboxylic acid is more preferably 90 mol% or more.

  Examples of the long-chain aliphatic dicarboxylic acid having 6 to 10 carbon atoms include adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid. Of these, adipic acid and sebacic acid are preferred because they are easily available industrially.

  As said aliphatic dicarboxylic acid, other aliphatic dicarboxylic acids other than C6-C10 long-chain aliphatic dicarboxylic acid may be included. Examples of other aliphatic dicarboxylic acids include succinic acid, glutaric acid, dodecanedioic acid and the like.

  The dicarboxylic acid used as a raw material for the polyamide resin of the present invention may include an alicyclic dicarboxylic acid or a heterocyclic dicarboxylic acid as another dicarboxylic acid other than the aromatic dicarboxylic acid and the aliphatic dicarboxylic acid.

  As a raw material of the polyamide resin of the present invention, the ratio of the diamine and the dicarboxylic acid is preferably -2 mol% to +2 mol% of the diamine from the viewpoint of the polymerization reaction. When the ratio of the dicarboxylic acid exceeds the range of diamine, it is difficult to increase the degree of polymerization of the polyamide resin, so that it takes a lot of time to increase the degree of polymerization, and thermal deterioration may easily occur. The proportion of dicarboxylic acid is more preferably -1 mol% to +1 mol% of the diamine.

The polyamide resin of the present invention preferably has a number average molecular weight (Mn) in the range of 10,000 to 50,000 in gel permeation chromatography (GPC) measurement. By setting the number average molecular weight (Mn) within the above range, the mechanical strength in the case of forming a molded article is stable, and the moldability has an appropriate melt viscosity that provides good workability. The number average molecular weight (Mn) is more preferably in the range of 12,000 to 40,000, and still more preferably in the range of 14,000 to 30,000.
Further, the dispersity (weight average molecular weight / number average molecular weight = Mw / Mn) is preferably in the range of 1.5 to 6.0. By setting the dispersity within the above range, the fluidity at the time of melting and the stability of the melt viscosity are increased, and the workability of melt kneading and melt molding is improved. Also, the toughness is good, and various physical properties such as water absorption resistance, chemical resistance, and heat aging resistance are also good. The degree of dispersion is more preferably in the range of 1.5 to 3.5.

  As the polyamide resin of the present invention, the polyamide resin produced by the polycondensation reaction can be used as it is, but it may be subjected to a step for further increasing the degree of polymerization. Further examples of the step of increasing the degree of polymerization include reactive extrusion in an extruder and solid phase polymerization. As a heating device used in solid phase polymerization, a continuous heating drying device, a tumble dryer, a conical dryer, a rotary drum heating device called a rotary dryer, etc., and a rotary blade inside a nauta mixer are provided. A conical heating device can be preferably used. Solid-phase polymerization is performed by, for example, polymerizing a low molecular weight polyamide resin in the form of pellets or powder and heating it in a temperature range from 150 ° C. to the melting point of the polyamide resin under reduced pressure or in an inert gas atmosphere. .

In the polycondensation reaction of the polyamide resin of the present invention, a phosphorus atom-containing compound may be added to accelerate the amidation reaction. Examples of the phosphorus atom-containing compound include phosphinic acid compounds such as dimethylphosphinic acid; diphosphorous acid such as hypophosphorous acid, sodium hypophosphite, potassium hypophosphite, magnesium hypophosphite, and calcium hypophosphite. Acid compounds; Phosphonic acid compounds such as sodium phosphonate, potassium phosphonate, potassium phosphonate, magnesium phosphonate, and calcium phosphonate; Phosphonic acid compounds: Phosphorous acid compounds such as sodium hydrogen phosphite, sodium phosphite, potassium phosphite, magnesium phosphite, calcium phosphite, triethyl phosphite and the like.
Among these, hypophosphite metal salts such as sodium hypophosphite and potassium hypophosphite are particularly preferable because they have a high effect of promoting the amidation reaction and are excellent in an anti-coloring effect.
The amount of the phosphorus atom-containing compound added is preferably 0.1 to 1000 ppm in terms of phosphorus atom concentration in the polyamide resin. When the addition amount of the phosphorus atom-containing compound is less than 0.1 ppm, the polymerization time is prolonged, the polyamide resin is colored, and the transparency may be lowered. If it exceeds 1000 ppm, the polyamide resin is likely to be gelled, or fish eyes considered to be attributable to the phosphorus atom-containing compound are mixed into the molded product, which may deteriorate the appearance of the molded product. The addition amount of the phosphorus atom-containing compound is more preferably 1 to 600 ppm, and further preferably 5 to 400 ppm.

  In the polycondensation reaction of the polyamide resin of the present invention, an alkali metal compound can be added in combination with the phosphorus atom-containing compound. In order to prevent the polyamide resin from being colored during the polycondensation reaction, it is preferable that a sufficient amount of phosphorus atom-containing compound is present, but the polyamide resin may be gelled, so that the amidation reaction rate is adjusted. It is preferable to coexist an alkali metal compound. As the alkali metal compound, alkali metal hydroxide, alkali metal acetate, alkali metal carbonate, alkali metal alkoxide, and the like are preferable. Specific examples of the alkali metal compound include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, lithium acetate, sodium acetate, potassium acetate, cesium acetate, sodium carbonate and the like. The ratio between the phosphorus atom-containing compound and the alkali metal compound is such that phosphorus atom-containing compound / alkali metal compound = 1.0 / 0.05 to 1.0 / 1. The range of 5 is preferable, the range of 1.0 / 0.1 to 1.0 / 1.2 is more preferable, and the range of 1.0 / 0.2 to 1.0 / 1.1 is still more preferable.

  The polyamide resin of the present invention includes a lubricant, a crystallization nucleating agent, an anti-whitening agent, a matting agent, a heat stabilizer, a weather stabilizer, an ultraviolet absorber, a plasticizer, and a flame retardant according to the required use and performance. Additives such as antistatic agents, anti-coloring agents, antioxidants, impact resistance improvers and the like can be added. The additive can be added as necessary as long as the effects of the present invention are not impaired. The mixing of the polyamide resin and the additive is preferably dry mixing at a low cost and not subject to thermal history. For example, a method in which a polyamide resin and the additive are put in a tumbler and mixed by rotating is mentioned.

  The gas barrier multilayer molded article of the present invention is a gas barrier multilayer having transparency and heat resistance obtained by joining at least one gas barrier layer containing the polyamide resin of the present invention and at least one layer containing another thermoplastic resin. It is a molded body. Examples of the multilayer molded body include sheets, films, tubes and bottles, containers such as cups and cans, bags, and the like composed of a layer containing the polyamide resin of the present invention and a layer containing another thermoplastic resin. It is done.

  In the gas barrier multilayer molded article of the present invention, the melting point of the polyamide resin used for the gas barrier layer is preferably in the range of 180 ° C. or higher and lower than 220 ° C., more preferably 180 ° C. or higher and 215 ° C. or lower. . By bringing the melting point of the polyamide resin close to that of other thermoplastic resins, it is possible to reduce the generation of odor and coloring due to resin deterioration during the formation of a multilayer molded body.

In the gas barrier multilayer molded article of the present invention, the oxygen permeability coefficient of the polyamide resin used in the gas barrier layer under the conditions of 20 ° C. and 65% relative humidity (hereinafter sometimes abbreviated as “RH”) is 2 It is preferably within a range of 0.0 ml · mm / m ² · day · MPa or less. The value of the oxygen permeability coefficient is preferably lower. When the oxygen permeability coefficient exceeds 2.0 ml · mm / m ² · day · MPa, the polyamide resin layer is thickened in order to obtain performance required for practical use. Therefore, not only the secondary workability is degraded, but also the mechanical properties of the multilayer molded body are degraded. Moreover, since the amount of expensive polyamide resin used is increased compared to polyolefin, PET, etc., it is economically disadvantageous.

  In the gas barrier multilayer molded article of the present invention, the thickness ratio of the gas barrier layer to the total thickness of the multilayer molded article is preferably 1 to 50%. By setting the thickness ratio of the gas barrier layer in this range, a multilayer molded article having both gas barrier performance and good secondary workability and mechanical properties can be obtained. On the other hand, when the thickness ratio is less than 1%, the gas barrier performance of the multilayer molded article cannot be sufficiently obtained. If the thickness ratio exceeds 50%, sufficient gas barrier performance can be obtained, but secondary workability such as deep drawing may be deteriorated.

  The gas barrier multilayer molded article is obtained by co-extrusion of the polyamide resin of the present invention and another thermoplastic resin, co-injection molding, and blow molding, deep drawing molding and stretching into a precursor such as a sheet, film or parison obtained. Excellent heat resistance and transparency that do not cause deformation, such as shrinkage and expansion, and whitening even in hot water treatment for sterilization purposes and high-temperature filling of foods and beverages. It is a multilayer molded article having a high gas barrier property.

  Examples of the other thermoplastic resins include polyolefin resins, polystyrene resins, polyester resins, polycarbonate resins, and other polyamide resins. Further, these resins can be used in a mixture as long as the transparency is not lost completely.

  Examples of the polyolefin resin include polyethylene, polypropylene, or two or more types of polyolefin copolymers such as ethylene, propylene, and butene, and mixtures thereof. Examples of the polyester resin include polyethylene terephthalate, polycyclohexane dimethylene terephthalate, polycyclohexane dimethylene isophthalate, polyethylene naphthalene dicarboxylate, and copolymer polyesters mainly composed of the component units of the polyester.

  Examples of the other polyamide resins include aliphatic polyamides such as nylon 6, nylon 66, nylon 11, nylon 12, nylon 46, nylon 610, and the like, and copolymer polyamides mainly composed of component units forming the polyamide. It is done.

  In the case of containers intended for water-containing foods and beverages that need to be hot-filled, the outer layer is usually separated so that the layer containing the polyamide resin of the present invention absorbs water and the gas barrier properties and mechanical properties do not deteriorate. It is preferable to use a layer containing the thermoplastic resin. Further, in order to improve the adhesion between the layers, an adhesive resin between the layer containing the polyamide resin of the present invention and a layer containing another thermoplastic resin or between layers containing two different kinds of thermoplastic resins. A multilayer molded body provided with a layer can also be used as the present invention. A multilayer molded article provided with a layer of a composition in which an adhesive resin is melt-mixed with a thermoplastic resin of polyester, polyamide, polycarbonate and polyolefin in order to improve the adhesion between layers can also be used as the present invention. .

  The multilayer molded body of the present invention can be produced by co-extrusion based on an inflation method, a T-die method, or the like, and sandwich injection in which two or more kinds of molten resins are sequentially injected into a mold and co-injection molding called two-color molding. Sheets, films, tubes and containers produced by coextrusion and co-injection molding can be used as they are, or can be used as containers or bags by some heating and heat sealing or other bonding methods. Used as a container for bottles, cups and the like by performing secondary processing with stretching such as blow molding and deep drawing including parison. Further, the sheet and the film can be used after being stretched as a bag-like material by heat sealing or other adhesion methods.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited only to these Examples. The polyamide resins obtained in Examples and Comparative Examples and gas barrier multilayer molded articles were evaluated by the following methods.

(1) Number average molecular weight and degree of dispersion Gel permeation chromatography (GPC) (manufactured by Showa Denko, trade name Shodex GPC SYSTEM-21) was used, the solvent was hexafluoroisopropanol (HFIP), and the measurement column was made by Showa Denko. Two organic solvent SEC (GPC) columns GPC HFIP-806M, two reference columns HFIP-800, the column temperature was 40 ° C., and the solvent flow rate was 1.0 mL / min. PMMA was used as the standard sample, and the number average molecular weight (Mn) and the weight average molecular weight (Mw) were determined.
The degree of dispersion was calculated from the degree of dispersion = (weight average molecular weight / number average molecular weight).
(2) Glass transition temperature and melting point Using a differential scanning calorimeter (manufactured by Shimadzu Corporation, trade name: DSC-60), DSC measurement (differential scanning calorimetry) was performed in a nitrogen stream at a heating rate of 10 ° C / min. The glass transition temperature (Tg) and the melting point (Tm) were determined.
(3) Oxygen permeability coefficient Using an oxygen permeability measuring device (Mocon, model: OX-TRAN 2 / 21SH) according to ASTM D3985, the oxygen permeability at 20 ° C. and 65% RH of a 100 μm film was measured. The oxygen permeability coefficient was converted into (ml · mm / (m ² · day · MPa)).
(4) Haze value and yellowness According to JIS-K-7105, a film sample having a thickness of about 100 μm is measured with a color difference / cloudiness measuring device (manufactured by Nippon Denshoku Industries Co., Ltd., model: COH-300A). did.

(Polyamide resin synthesis)
Example 1
In a reactor with a jacket equipped with a stirrer, a partial condenser, a cooler, a thermometer, a dropping tank, and a nitrogen gas introduction tube, 14320 g (98.0 mol) of adipic acid and 330 g of isophthalic acid (2. 0 mol), and after sufficiently purging with nitrogen, the temperature was further raised to 170 ° C. under a nitrogen stream to bring the dicarboxylic acid into a melt-flow state, and then 12550 g (99.5 mol) of 2,5-bis (aminomethyl) furan. Was added dropwise with stirring. During this time, the internal temperature was continuously raised to 245 ° C., and the distilled water was removed out of the system through a partial condenser and a cooler. After the completion of 2,5-bis (aminomethyl) furan dropwise addition, the internal temperature is raised to 255 ° C, and then the internal pressure of the reaction system is continuously reduced to 80 kPa, and the reaction temperature is continuously raised to 260 ° C. It was. After completion of the reaction, the inside of the reactor was pressurized with nitrogen gas at a pressure of 0.2 MPa, the polymer was taken out as a strand from the nozzle at the bottom of the polymerization tank, cut after water cooling, and a pellet-shaped polyamide resin was obtained.
Further, the pellets were charged into a stainless steel drum-type heating device, sufficiently purged with nitrogen, and the reaction system was heated from room temperature to 140 ° C. under a small amount of nitrogen. When the internal temperature of the reaction system reached 140 ° C, the pressure was reduced to 0.133 kPa or less, and the internal temperature was further increased to 180 ° C. The reaction was continued at 180 ° C., and after completion of the reaction, the pellet was taken out when the temperature reached 60 ° C. to obtain a polyamide resin (1). The obtained polyamide resin (1) had a number average molecular weight of 24,200, a degree of dispersion of 2.4, a melting point of 217 ° C., and a glass transition temperature of 97 ° C. A single-layer unstretched film was produced from the polyamide resin (1) using a single-screw small extruder with a T-die (Laboplast Mill manufactured by Toyo Seiki Seisakusho Co., Ltd.). The oxygen permeability coefficient of the obtained film was 0.17 ml · mm / m ² · day · MPa. Table 1 shows the resin composition and evaluation results.

(Example 2)
A polyamide resin (2) was synthesized in the same manner as in Example 1 except that 13880 g (95.0 mol) of adipic acid and 830 g (5.0 mol) of isophthalic acid were used as the dicarboxylic acid in the same reactor as in Example 1. did. The obtained polyamide resin (2) had a number average molecular weight of 24,800, a degree of dispersion of 2.4, a melting point of 213 ° C., and a glass transition temperature of 98 ° C. The oxygen permeability coefficient of the single-layer unstretched film was 0.18 ml · mm / m ² · day · MPa.

(Example 3)
A polyamide resin (3) was synthesized in the same manner as in Example 1, except that 12420 g (85.0 mol) of adipic acid and 2490 g (15.0 mol) of isophthalic acid were used as the dicarboxylic acid in the same reactor as in Example 1. did. The number average molecular weight of the obtained polyamide resin (3) was 25600, the degree of dispersion was 2.5, the melting point was 194 ° C., and the glass transition temperature was 105 ° C. The oxygen transmission coefficient of the single-layer unstretched film was 0.23 ml · mm / m ² · day · MPa.

Example 4
A polyamide resin (4) was synthesized in the same manner as in Example 1 except that 11690 g (80.0 mol) of adipic acid and 3320 g (20.0 mol) of isophthalic acid were used as the dicarboxylic acid in the same reactor as in Example 1. did. The number average molecular weight of the obtained polyamide resin (4) was 23000, the degree of dispersion was 2.6, the point was 187 ° C., and the glass transition temperature was 109 ° C. The oxygen permeability coefficient of the single-layer unstretched film was 0.24 ml · mm / m ² · day · MPa.

(Example 5)
A polyamide resin (5) was synthesized in the same manner as in Example 1 except that 10960 g (75.0 mol) of adipic acid and 4150 g (25.0 mol) of isophthalic acid were used as the dicarboxylic acid in the same reactor as in Example 1. did. The obtained polyamide resin (5) had a number average molecular weight of 22,300, a dispersity of 2.7, a melting point not detected, and a glass transition temperature of 112 ° C. The oxygen permeability coefficient of the single-layer unstretched film was 0.36 ml · mm / m ² · day · MPa.

(Example 6)
A polyamide resin (6) was synthesized in the same manner as in Example 1 except that 10230 g (70.0 mol) of adipic acid and 4980 g (30.0 mol) of isophthalic acid were used as the dicarboxylic acid in the same reactor as in Example 1. did. The number average molecular weight of the obtained polyamide resin (6) was 22200, the degree of dispersion was 2.7, the melting point was not detected, and the glass transition temperature was 117 ° C. The oxygen permeability coefficient of the single-layer unstretched film was 0.48 ml · mm / m ² · day · MPa.

(Comparative Example 1)
A polyamide resin (7) was synthesized in the same manner as in Example 1 except that 14610 g (100.0 mol) of adipic acid was used as the dicarboxylic acid in the same reactor as in Example 1. The number average molecular weight of the obtained polyamide resin (7) was 23000, the degree of dispersion was 2.4, the melting point was 220 ° C., and the glass transition temperature was 92 ° C. The oxygen transmission coefficient of the single-layer unstretched film was 0.16 ml · mm / m ² · day · MPa.

(Comparative Example 2)
A polyamide resin (8) was synthesized in the same manner as in Example 1 except that 8770 g (60.0 mol) of adipic acid and 6640 g (40.0 mol) of isophthalic acid were used as the dicarboxylic acid in the same reactor as in Example 1. did. The number average molecular weight of the obtained polyamide resin (8) was 21,800, the degree of dispersion was 2.8, the melting point was not detected, and the glass transition temperature was 122 ° C. The oxygen permeability coefficient of the single-layer unstretched film was 1.01 ml · mm / m ² · day · MPa.

(Example 7)
A polyamide resin (9) was synthesized in the same manner as in Example 1 except that 18200 g (90.0 mol) of sebacic acid and 1660 g (10.0 mol) of isophthalic acid were used as the dicarboxylic acid in the same reactor as in Example 1. did. The number average molecular weight of the obtained polyamide resin (9) was 18300, the degree of dispersion was 2.4, the melting point was not detected, and the glass transition temperature was 82 ° C. The oxygen permeability coefficient of the single-layer unstretched film was 1.37 ml · mm / m ² · day · MPa.

(Comparative Example 3)
A polyamide resin (10) was synthesized in the same manner as in Example 1, except that 20220 g (100.0 mol) of sebacic acid was used as the dicarboxylic acid in the same reactor as in Example 1. The obtained polyamide resin (10) had a number average molecular weight of 17,200, a degree of dispersion of 2.4, a melting point of 170 ° C. and a glass transition temperature of 72 ° C. The oxygen permeability coefficient of the single-layer unstretched film was 1.30 ml · mm / m ² · day · MPa.

(Manufacture of gas barrier multilayer molded products)
(Example 8)
The polyamide resin (1) obtained in Example 1 was used as a gas barrier layer, a polypropylene layer as another thermoplastic resin, and a modified polypropylene (trade name: Modic P553A, manufactured by Mitsubishi Chemical Corporation) as an adhesive layer between the two layers. In a multilayer sheet manufacturing apparatus comprising an extruder, a feed block, a T-die, and a take-up machine so that the layer structure is in the order of polypropylene layer / adhesive layer / gas barrier layer / adhesive layer / polypropylene layer, a five-layer multilayer sheet molded product Was made. The extrusion temperature of each resin during sheet production was 230 ° C. for the polypropylene layer, 200 ° C. for the adhesive layer, 230 ° C. for the gas barrier layer, and 230 ° C. for the feed block temperature. There was almost no odor due to polypropylene deterioration during extrusion. The multilayer sheet molded body thus obtained had a Haze value of 27% and a yellowness of 1.0. The total thickness of the sheet was 0.8 mm, and the thickness of the gas barrier layer was 0.04 mm.
Next, the produced multilayer sheet molded body was deep-drawn thermoformed into a cup-shaped container having a depth of 25 mm, an opening diameter of 65 mm, and a bottom diameter of 50 mm using a vacuum / pressure forming machine. The thermoforming was performed by heating the surface temperature to 170 ° C. using a ceramic heater and then quickly vacuum-pressure forming. The thermoformability to the container was very good, and a container having a uniform gas barrier layer thickness and good transparency could be obtained. The obtained container was filled with water, covered with an aluminum foil having a heat seal layer, and the oxygen permeability of the container at 20 ° C. and 65% RH in a state of being welded and sealed by a heat seal machine was 0.003 ml / package day (0.021 MPa).

(Examples 9 to 14)
Using the polyamide resins (2) to (6) and (9) obtained in Examples 2 to 7 as gas barrier layers, a 5-layer multilayer sheet molded article was produced in the same manner as in Example 8. Further, it was molded into a container by a vacuum / pressure forming machine in the same manner as in Example 8. Table 2 shows molding conditions and evaluation results.

(Comparative Examples 4-6)
Using the polyamide resins (7), (8) and (10) obtained in Comparative Examples 1 to 3 as gas barrier layers, a 5-layer multilayer sheet molded article was produced in the same manner as in Example 8. Further, it was molded into a container by a vacuum / pressure forming machine in the same manner as in Example 8. Table 2 shows molding conditions and evaluation results.

(Example 14)
The polyamide resin (2) obtained in Example 2 is used as a gas barrier layer, a polyethylene terephthalate (PET) layer as another thermoplastic resin, and the layer configuration is in the order of PET layer / gas barrier layer / PET layer / gas barrier layer / PET layer. In this manner, the injection molding machine sequentially injects into the same mold to form a parison having a multilayer structure of five layers. The obtained parison was blow-molded at a blow pressure of 20 kg / cm ² and a blow molding temperature of 110 ° C. to form a 5-layer bottle. The obtained five-layer bottle molded product had excellent transparency, had a Haze value of 1.7% and a yellowness of 0.5. The total thickness of the trunk was 360 μm, the total thickness of the gas barrier layer was 25 μm, and the oxygen transmission rate at 50% RH was 0.0075 ml / package day (0.021 MPa).

  The polyamide resins of Examples 1 to 7 all have high gas barrier performance, and also have a relatively high glass point transition temperature and a relatively low melting point, so that multilayer molding is performed as in Examples 8 to 14. When molding as a body, by setting the molding temperature low, the obtained multilayer molded body can maintain high transparency and high gas barrier performance.

  On the other hand, the polyamide resin of Comparative Example 1 has high gas barrier performance, but has a high melting point or a low glass point transfer temperature, so that it is molded as a multilayer molded body as in Comparative Example 4. When the molding temperature is increased, odor due to deterioration of the polypropylene and the adhesive layer material is generated, transparency is lowered, and the thickness of each layer is partially non-uniform so that the gas barrier property is lowered. Further, in the polyamide resin of Comparative Example 2, the gas barrier property was lowered because the mol% of the aromatic dicarboxylic acid was high. Also, fusion between the pellets occurred during drying of the pellets or in the solid phase polymerization process, and handling was reduced.

  The molded body using the polyamide resin having gas barrier properties of the present invention can withstand heat treatment and hot filling, and has excellent transparency and gas barrier performance with little coloring during production and secondary processing, It can be suitably used for packaging films, containers, beverage bottles and the like.

Claims (4)

  A polyamide resin obtained from a polycondensation reaction between a diamine containing bis (aminomethyl) furan and a dicarboxylic acid containing an aliphatic dicarboxylic acid and an aromatic dicarboxylic acid, the proportion of bis (aminomethyl) furan in the diamine 60 mol% or more, the ratio of the aliphatic dicarboxylic acid in the dicarboxylic acid is 70 mol% to 98 mol%, and the ratio of the aromatic dicarboxylic acid is 2 mol% to 30 mol%.   The polyamide resin according to claim 1, wherein the aromatic dicarboxylic acid contains 50 mol% or more of isophthalic acid.   The polyamide resin according to claim 1 or 2, wherein the aliphatic dicarboxylic acid contains 80 mol% or more of a long-chain aliphatic dicarboxylic acid having 6 to 10 carbon atoms.   A gas barrier multilayer molded article formed by joining at least one gas barrier layer containing the polyamide resin according to any one of claims 1 to 3 and at least one layer containing another thermoplastic resin.