WO2006129378A1

WO2006129378A1 - Gas barrier polymer material having novel phase separation structure

Info

Publication number: WO2006129378A1
Application number: PCT/JP2005/010437
Authority: WO
Inventors: Kikuo Arimoto; Keisuke Morikawa; Nobuhiro Moriguchi; Toshiaki Ougizawa
Original assignee: Kuraray Co., Ltd.
Priority date: 2005-05-31
Filing date: 2005-05-31
Publication date: 2006-12-07

Abstract

Provision of a gas barrier polymer material having higher gas barrier property as compared to conventional gas barrier polymer materials having the same chemical species.The gas barrier polymer material of the present invention comprises a hydroxyl group-containing gas barrier polymer having a phase separation structure comprising two or more co-continuous regions, which mainly comprises a structural unit represented by the following formula (I) wherein m and n are each an integer of 0 to 10; X1 and X2 are each a hydrogen atom, a hydroxyl group or a functional group convertible to a hydroxyl group, provided that the total of m and n is not less than 1 and at least one of X1 and X2 is a hydroxyl group or a functional group convertible to a hydroxyl group; R1, R2 and R3 are each a hydrogen atom, a hydroxyl group, a functional group convertible to a hydroxyl group, an alkyl group, an aryl group, an aralkyl group or a heteroaryl group; and R1, R2, R3, X1and X2 present in plurality are optionally the same as or different from each other.

Description

Description GAS BARRIER POLYMER MATERIAL HAVING NOVEL PHASE SEPARATION

STRUCTURE Technical Field The present invention relates to a gas barrier polymer material. More particularly, the present invention relates to a gas barrier polymer material showing extremely high gas barrier property conventionally difficult to achieve.

Background Art The gas barrier property of polymer shows values specific to each chemical species such as polyethylene (PE) , polystyrene (PS) , polyethylene terephthalate (PET) , ethylene-vinyl alcohol copolymer (EVOH) and the like. In the case of polymers belonging to the same chemical species (having the same molecular weight, molecular weight distribution, branch degree and the like) , crystalline polymers are superior to non-crystalline polymers in the gas barrier property. However, due to tangles characteristic of polymers, a single crystal material having homogeneous property in the entirety thereof cannot be obtained, and polymers generally show a high order structure wherein a crystal phase, an amorphous phase and an intermediate phase are entangled. Heretofore, for the purpose of improving mechanical strength of polymers, a technique for controlling high order structures of a crystal phase, an amorphous phase and an intermediate phase has been proposed (JP-A-2000-248128) . As the situation stands, as a technique for modifying a polymer itself for the purpose of improving gas barrier property of the polymer, the proportion of crystal phase is increased, namely, a nucleating agent and the like are added to improve the degree of crystallinity (JP-A-2002- 69320) . However, use of additives such as nucleating agent and the like is not desirable in view of the environmental problems and extra steps that become necessary, and, what is more, the modification effect afforded thereby is not entirely sufficient. Disclosure of the Invention

The present invention has been made in view of the above- mentioned situation, and the problem to be solved is provision of a gas barrier polymer material capable of expressing sufficiently high gas barrier property without addition of a nucleating agent to the gas barrier polymer material.

The present inventors have conducted intensive studies in an attempt to solve the above-mentioned problem and found that, while polymers show special phase separation (thermally induced non-equilibrium liquid - liquid phase separation) before crystallization, phase separation occurs in high density region and low density region, resulting in co-continuity of respective regions up to a certain time before the start of the crystallization under certain temperature conditions, and that the gas barrier property of a hydroxyl group-containing gas barrier polymer having a structure comprising two or more co- continuous regions having different densities is markedly improved as compared to that of polymers without such structure, and further studied based on the findings, which resulted in the completion of the present invention.

Accordingly, the present invention relates to

[1] a gas barrier polymer material comprising a hydroxyl group- containing gas barrier polymer having a phase separation structure comprising two or more co-continuous regions, which mainly comprises a structural unit represented by the following formula (I)

wherein m and n are each an integer of 0 to 10; X¹ and X² are each a hydrogen atom, a hydroxyl group or a functional group convertible to a hydroxy! group, provided that the total of m and n is not less than 1 and at least one of X¹ and X² is a hydroxyl group or a functional group convertible to a hydroxyl group; R¹, R² and R³ are each a hydrogen atom, a hydroxyl group, a functional group convertible to a hydroxyl group, an alkyl group, an aryl group, an aralkyl group or a heteroaryl group; and R¹, R², R³, X¹ and X² present in plurality are optionally the same as or different from each other,

[2] the gas barrier polymer material of the above-mentioned [1], which shows an amount of oxygen permeation at 2O⁰C, 90% RH of not more than 1 cc^§20 μm/m^2#dayatm,

[3] a packaging material comprising a gas barrier polymer material of the above-mentioned [1] or [2], and

[4] a production method of a gas barrier polymer material of the above-mentioned [1], which comprises Step A comprising cooling a molten product of the hydroxyl group-containing gas barrier polymer or a resin composition comprising the hydoroxyl group- containing gas barrier polymer to a temperature within the range of from a temperature lower than the melting point of the hydroxyl group-containing gas barrier polymer by 100°C (Tm-IOO⁰C) to the melting point (Tm⁰C) and retaining the molten product within the aforementioned temperature range for not less than 2 minutes, wherein the hydroxyl group-containing gas barrier polymer mainly comprises a structural unit represented by the following formula (I) :

(D wherein m and n are each an integer of 0 to 10;

X¹ and X² are each a hydrogen atom, a hydroxyl group or a functional group convertible to a hydroxyl group, provided that the total of iti and n is not less than 1 and at least one of X¹ and X² is a hydroxyl group or a functional group convertible to a hydroxyl group; R¹, R² and R³ are each a hydrogen atom, a hydroxyl group, a functional group convertible to a hydroxyl group, an alkyl group, an aryl group, an aralkyl group or a heteroaryl group; and R¹, R², R³, X¹ and X² present in plurality are optionally the same as or different from each other.

Since the gas barrier polymer material of the present invention comprises a hydroxyl group-containing gas barrier polymer having a phase separation structure wherein two or more regions are co-continuous, it effectively blocks or extends a gas diffusion path and shows high gas barrier property that conventional gas barrier polymers of the same chemical species (gas barrier polymer materials substantially the same in the kind of structural unit (monomer) , composition, molecular weight, molecular weight distribution, branch degree and the like) have failed to achieve, thereby affording a polymer material having sufficiently high gas barrier property.

Conventionally, for example, when a polymer material of a packaging material shows insufficient gas barrier property by itself, a gas barrier layer, such as an aluminum foil, an aluminum vapor deposition layer, a silicon oxide vapor deposition layer and the like, has been formed. Since the gas barrier polymer material of the present invention shows extremely high gas barrier property, the present invention can solve the defect that lamination of an aluminum foil, an aluminum vapor deposition layer, a silicon oxide vapor deposition layer and the like conceals the contents of packages and a problem of lower disposability of packaging materials and the like. Brief Description of the Drawings

Fig. 1 is a DSC chart of the hydrogenated poly(5- cyclooctene-l,2-diol) of Example 1.

Fig. 2 shows light scattering intensity of hydrogenated poly (5-cyclooctene-l,2-diol) of Example 1 in a retention time (0- 240 min) after melt-cooling.

Fig. 3 is a confocal scanning laser micrograph (copy) of a co-continuous phase separation structure of hydrogenated poly (5- cyclooctene-l,2-diol) of Example 1.

Fig. 4 is a DSC chart of hydrogenated poly (5-cyclooctene- 1,2-diol) of Example 2.

Fig. 5 shows light scattering intensity of hydrogenated poly (5-cyclooctene-l,2-diol) of Example 2 in a retention time (0- 110 min) after melt-cooling.

Fig. 6 is a DSC chart of hydrogenated poly(5-cyclooctene- 1,2-diol) of Comparative Example 1.

Fig. 7 shows light scattering intensity of hydrogenated poly (5-cyclooctene-l, 2-diol) of Comparative Example 1 in a retention time (0-120 min) after melt-cooling.

Fig. 8 is a confocal scanning laser micrograph (copy) of hydrogenated poly (5-cyclooctene-l, 2-diol) of Comparative Example 1.

Best Mode for Embodying the Invention The present invention is explained in detail in the following. The gas barrier polymer material of the present invention comprises a hydroxyl group-containing gas barrier polymer having a phase separation structure wherein two or more regions are co- continuous . The hydroxyl group-containing gas barrier polymer to be used in the present invention comprises a main structural unit represented by the following formula (I) :

wherein m and n are each an integer of 0 to 10;

X¹ and X² are each a hydrogen atom, a hydroxyl group or a functional group convertible to a hydroxyl group, provided that the total of m and n is not less than 1 and at least one of X¹ and X² is a hydroxyl group or a functional group convertible to a hydroxyl group/ R¹, R² and R³ are each a hydrogen atom, a hydroxyl group, a functional group convertible to a hydroxyl group, an alkyl group, an aryl group, an aralkyl group or a heteroaryl group; and R¹, R², R³, X¹ and X² present in plurality are optionally the same as or different from each other. In the above-mentioned formula (I) , X¹ and X² are each a hydrogen atom, a hydroxyl group or a functional group convertible to a hydroxyl group. However, at least one of X¹ and X² is a hydroxyl group or a functional group convertible to a hydroxyl group. When X¹ and X² are present in plurality, they may be the same as or different from each other.

As the above-mentioned functional group convertible to a hydroxyl group, for example, an epoxy group, a hydroxyl group protected by a protecting group and the like can be mentioned. As the epoxy group, a 3-membered ring structure consisting of a carbon atom bonded to X¹, a carbon atom bonded to X² and an oxygen atom can be mentioned.

As the above-mentioned hydroxyl-protecting group, for example, alkyl groups such as methyl group, ethyl group, t-butyl group and the like; alkenyl groups such as allyl group and the like; aralkyl groups such as benzyl group and the like; aryl groups such as phenyl group and the like; alkoxyalkyl groups such as methoxymethyl group, methoxyethyl group, ethoxyethyl group and the like; acyl groups such as acetyl group, propionyl group, benzoyl group and the like; alkoxycarbonyl groups such as methoxycarbonyl group, ethoxycarbonyl group, t-butoxy carbonyl group, phenyloxycarbonyl group, benzyloxycarbonyl group and the like; silyl groups such as trimethylsilyl group, t- butyldimethylsilyl group and the like; and the like can be mentioned. Of these, alkoxyalkyl groups such as methoxymethyl group, methoxyethyl group, ethoxyethyl group and the like; acyl groups such as acetyl group, propionyl group, benzoyl group and the like; alkoxycarbonyl groups such as methoxycarbonyl group, ethoxycarbonyl group, t-butoxycarbonyl group, phenyloxycarbonyl group, benzyloxycarbonyl group and the like; hydroxyl group protected by silyl group, such as trimethylsilyl group, t- butyldimethylsilyl group and the like; and the like can be preferably used, because protection and deprotection are easy. Particularly, since economical industrial preparation is available, acyl groups such as acetyl group, propionyl group, benzoyl group and the like are more preferable.

In the above-mentioned formula (I) , X¹ and X² are each preferably a hydroxyl group and/or a functional group convertible to a hydroxyl group. In the above-mentioned formula (I) , R¹, R² and R³ are each a hydrogen atom, a hydroxyl group, a functional group convertible to a hydroxyl group, an alkyl group, an aryl group, an aralkyl group or a heteroaryl group. When R¹, R² and R³ are present in plurality, they may be the same as or different from each other.

As the functional group convertible to a hydroxyl group for R¹, R² or R³, for example, those exemplified as the functional group convertible to a hydroxyl group for the above-mentioned X¹ or X² can be mentioned.

As the alkyl group for R¹, R² or R³, an alkyl group having 1 to 5 carbon atoms is preferable. As such alkyl group, for example, fatty chain alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, n-pentyl group and the like; alicyclic alkyl groups such as cyclopentyl group and the like; and the like can be mentioned.

As the aryl group for R¹, R² or R³, for example, phenyl group, naphthyl group, biphenyl group, phenanthryl group, anthryl group, triphenylenyl group, pyrenyl group and the like can be mentioned.

As the aralkyl group for R¹, R² or R³, for example, benzyl group, phenethyl group, naphthylmethyl group, biphenylmethyl group and the like can be mentioned.

As the heteroaryl group for R¹, R² or R³, for example, pyridyl group, quinolyl group, isoquinolyl group, pyrrolyl group, indolyl group, furyl group, benzofuranyl group, thienyl group, benzothiophenyl group and the like can be mentioned.

The hydroxyl group-containing gas barrier polymer to be used in the present invention preferably comprises a hydroxyl group or a functional group convertible to a hydroxyl group in a proportion of 1-500 mol%, more preferably 1-300 mol%, relative to the total mol amount of the repeat unit constituting the polymer.

Furthermore, the hydroxyl group-containing gas barrier polymer to be used in the present invention may consist only of a structural unit represented by the above-mentioned formula (I) or may comprise a structural unit other than the structural unit represented by the above-mentioned formula (I) . As the structural unit other than the structural unit represented by the above-mentioned formula (I) , for example, straight chain alkylene groups such as tetramethylene-1, 4-diyl group, pentamethylene-1, 5- diyl group, heptamethylene-l,7-diyl group, octamethylene-1, 8-diyl group and the like; branched chain alkylene groups such as 2- methylpentane-l,5-diyl group, 3-methylpentane-l, 5-diyl group and the like; alkylene groups having a ring structure such as cyclopentane-l,3-dimethylenediyl group and the like; and the like can be mentioned.

While the content of the structural unit represented by the above-mentioned formula (I) in the hydroxyl-containing gas barrier polymer to be used in the present invention is not particularly limited, it is preferably not less than 50 mol%, more preferably not less than 70 mol%, particularly preferably not less than 80 mol%, relative to the entire structural units constituting the polymer.

While the molecular weight of the hydroxyl group- containing gas barrier polymer to be used in the present invention is not particularly limited, the number average molecular weight (Mn) is preferably within the range of 1,000- 1,000,000, more preferably 1,000-200,000, still more preferably 1,000-80,000. When the number average molecular weight (Mn) is not more than 1,000,000, the polymer has suitable melt moldability. When the number average molecular weight (Mn) is less than 1,000, the mechanical strength becomes poor and film forming tends to be unattainable. As used herein, by the average molecular weight (Mn) is meant a value obtained by dissolving a hydroxyl group-containing gas barrier polymer in a solvent capable of dissolving the polymer, analyzing by gel permeation chromatography (GPC) and converting with poly (methyl methacrylate) as a standard substance.

The hydroxyl group-containing gas barrier polymer to be used in the present invention can be produced by a known production method. As examples thereof, a method according to a method comprising subjecting cyclic olefins containing at least one kind of cyclic olefin having a hydroxyl group or a functional group convertible to a hydroxyl group, to ring-opening polymerization in the presence of a metal alkylidene complex having a ligand with an imidazolidine structure (WO00/71554) , and subjecting the obtained unsaturated polymer to hydrogenation and the like can be mentioned (JP-A-2002-338621) .

The gas barrier polymer material of the present invention comprises the above-mentioned hydroxyl group-containing gas barrier polymer. The content of the hydroxyl group-containing gas barrier polymer in the gas barrier polymer material of the present invention is preferably within the range of 80-100 wt%, more preferably within the range of 90-100 wt%, still more preferably within the range of 95-100 wt%. The gas barrier polymer material of the present invention can contain components other than the hydroxyl group-containing gas barrier polymer as long as the effect of the invention is not impaired. That is, the material can be a composition (resin composition) containing a hydroxyl group-containing gas barrier polymer and components other than the hydroxyl group-containing gas barrier polymer. As such components, for example, conventionally known additives such as heat stabilizer, antioxidant, UV absorber, weather stabilizer, plasticizer, coloring agent, mold releasing agent, lubricant, flavoring, filler, surfactant and the like, and the like can be mentioned. The content of these components in the composition (resin composition) is preferably not more than 20 wt%, more preferably not more than 10 wt%, and still more preferably not more than 5 wt%. As mentioned above, it is essential that the hydroxyl group-containing gas barrier polymer contained in the gas barrier polymer material of the present invention should have a phase separation structure wherein two or more regions are co- continuous. As used herein, by the "phase separation structure wherein two or more regions are co-continuous" is meant a structure wherein two or more regions having different average densities and the like are three-dimensionally continued. A hydroxyl group-containing gas barrier polymer having such a structure effectively blocks or extends a gas diffusion path and the gas barrier property of a gas barrier polymer material can be enhanced to a higher level.

The gas barrier polymer material of the present invention can be produced by, but not limited to, Step A comprising cooling a molten product of a hydroxyl group-containing gas barrier polymer having a main structural unit represented by the above- mentioned formula (I) , or a molten product of a resin composition comprising the hydroxyl group-containing gas barrier polymer (i.e., a composition comprising the hydroxyl group-containing gas barrier polymer and a component other than the hydroxyl group- containing gas barrier polymer) to a temperature within the range of from a temperature lower than the melting point of the hydroxyl group-containing gas barrier polymer by 100°C (Tm-IOO⁰C) to the melting point (Tm⁰C) of the hydroxyl group-containing gas barrier polymer and maintaining the product within this temperature range for not less than 2 min, and then heat treating the product at any temperature. By the Step A, the hydroxyl group-containing gas barrier polymer in the molten product easily causes thermally induced non-equilibrium liquid - liquid phase separation before the start of crystallization. By the thermally induced non-equilibrium liquid - liquid phase separation, a hydroxyl group-containing gas barrier polymer forms a phase separation structure wherein two or more regions are co- continuous. Since a phase separation structure wherein two or more regions are co-continuous is formed in a hydroxyl group- containing gas barrier polymer before the start of crystallization, and then crystallization occurs, a structure having high barrier property, which comprises continuous high crystal-high density regions, is formed and a gas diffusion path is effectively blocked or extended, whereby the gas barrier property is enhanced to a higher level and sufficiently high gas barrier property conventionally unattainable can be achieved.

The treatment temperature in Step A may be constant or may vary as long as it is within the above-mentioned temperature range. In addition, Step A preferably includes a step of retaining at a temperature within the range of [any temperature selected from the above-mentioned temperature range] ±10°C for not less than 1 min, from the aspects of operability and reproducibility of properties. The heat treatment at any temperature after Step A is efficiently performed at generally (Tm-100) - Tm⁰C, preferably (Tm-70) - Tm⁰C, for about 5-120 min. The crystallization does not proceed at a temperature higher than Tm, and a temperature lower than (Tm-IOO)⁰C requires longer time for sufficient crystallization, unpreferably resulting in poor reproducibility and high cost.

In the present invention, the above-mentioned melting point of the hydroxyl group-containing gas barrier polymer is measured with a differential scanning calorimeter (DSC) .

When a gas barrier polymer material containing the aforementioned conventionally known additives (e.g., heat stabilizer, antioxidant, UV absorber, weather stabilizer, plasticizer, coloring agent, mold releasing agent, lubricant, flavoring, filler, surfactant etc.) is to be obtained, such can be obtained by melting a resin composition containing a hydroxyl group-containing gas barrier polymer and conventionally known additives and subjecting the composition to Step A. In this case, the conventionally known additives may be added during Step A, or partially added before Step A and the rest may be added during Step A.

In the present invention, the thermally induced non- equilibrium liquid - liquid phase separation of the hydroxyl group-containing gas barrier polymer in the above-mentioned Step A can be observed by light scattering methods. That is, when the thermally induced non-equilibrium liquid - liquid phase separation is in progress in the above-mentioned Step A, an exponential increase in the scattering intensity can be observed in a particular scattering vector. A phase separation structure wherein two or more regions are co-continuous, which is caused by thermally induced non-equilibrium liquid - liquid phase separation, can be also observed with a confocal scanning laser microscope and the like.

While the facility (apparatus) to be used for the production of the gas barrier polymer material of the present invention is not particularly limited, one capable of maintaining a gas barrier polymer material, which is equipped with a heat source, a control means to control the amount of heat from the heat source, a cooling means, a control means to control the amount of cooling by the cooling means and the like, and which can control the temperature of the gas barrier polymer material, is preferable.

A DSC-light scattering simultaneous measurement apparatus to be mentioned below, which comprises a DSC apparatus and an light scattering measurement apparatus in combination, can confirm in situ the formation of a desired co-continuous phase separation structure in a hydroxyl group-containing gas barrier polymer due to the thermally induced non-equilibrium liquid - liquid phase separation, since changes in the light scattering intensity of the hydroxyl group-containing gas barrier polymer can be measured simultaneously with melting of a gas barrier polymer to be used as a starting material, cooling to a given temperature after the melting and controlling temperature of the gas barrier polymer at a given temperature after the cooling.

The gas barrier polymer material of the present invention shows high gas barrier property, which is conventionally unattainable, and shows extremely high gas barrier property as evidenced by an amount of oxygen permeation of preferably not more than 1 cc-20 μm/m^2<dayatm, more preferably not more than 0.5 cc^#20 μm/m^2φdayatm, particularly preferably not more than 0.3 cc' 20 μm/m²*dayatm, under high humidity (90%RH) .

The gas barrier polymer material of the present invention can be used in the form of various molded products such as a film, a sheet, a container and the like by known forming methods for polymer materials, such as injection forming, blow molding, extrusion molding, inflation molding and the like. In addition, after processing into a film, a sheet and the like, it can be processed into various molded products by methods comprising deep draw molding such as vacuum molding, air pressure forming, vacuum air pressure forming and the like, and the like. While the use of the gas barrier polymer material of the present invention is not particularly limited as long as its extremely high gas barrier property can be effectively used, packaging materials for various products, particularly, packaging materials for food, beverage, pharmaceutical product and the like, specifically packaging materials for food. In this case, the packaging material may be in various forms such as a film, a sheet, a box, a container and the like can be mentioned. When a film or a sheet is formed, the thickness thereof is generally about 1-200 μm, preferably about 10-50 μm.

The present invention is explained in detail below by referring to Examples, which are not to be construed as limitative. The measurements in the following Examples and Comparative Examples followed the methods below. Confirmation of progress of thermally induced non-equilibrium liquid - liquid phase separation>

A DSC-light scattering simultaneous measurement apparatus was prepared by combining a differential scanning calorimeter (EXTAR6000) manufactured by Seiko and a light scattering measurement apparatus manufactured by Optec Technology Limited, and the time-course changes in the heat budget and light scattering intensity of the gas barrier polymer were measured by the apparatus. In the light scattering measurement, the scattering intensity (a.u.) was converted based on 1 μm thickness, and in the DSC measurement, the melting enthalpy (J) was converted based on 1 g weight. <measurement of melting point> Using differential scanning calorimeter DSC-7 manufactured by PerkinElmer, the temperature and melting enthalpy were corrected with lead and indium. After melting at 200°C for 5 min, the temperature was lowered to -50°C at 10°C/min and raised to 200°C at 10°C/min to determine the melting point (Tm) . <measurement of amount of oxygen permeation>

The amount of oxygen permeation of the films obtained in the following Examples and Comparative Examples was measured to evaluate the gas barrier property. MOCON OX-TRAN2/20 manufactured by Modern Control was used for the measurement of the amount of oxygen permeation, and the amount of oxygen permeation was measured under the conditions of 90%RH at 20°C according to the method described in JIS K 7126 (equal pressure method) . As used herein, the "amount of oxygen permeation" is a value of an amount of oxygen permeation (unit:cc/m²*dayatm) obtained by converting said amount measured at any membrane thickness, based on a membrane thickness of 20 μm (cc*20 μm/m^2# dayatm) . A smaller amount of oxygen permeation means more superior oxygen barrier property. <measurement of degree of crystallinity> The degree of crystallinity was measured according to the method described in Cerrada et al., Macromolecules, 31, 2259(1998) . <Reference Example 1> (a) [preparation of poly (5-cyclooctene-l, 2-diol) ]

In a separable flask (inner volume 3L) equipped with a thermometer, a dropping funnel, a refluxing tube and a stirrer were placed under an argon atmosphere 5-cyclooctene-l, 2-diol (320 g, 2.25 mol), 3-cis-hexen-l-ol (2.O g, 0.02 mol) as a chain transfer agent and tetrahydrofuran (1280 g) , and the mixture was retained at 55°C. To this solution was added dropwise with stirring a solution of 1, 3-bis (2, 4, 6-trimethylphenyl) -4, 5- dihydroimidazol-2-ylidene (tricyclohexylphosphine) benzylidene ruthenium dichloride (0.127 g, 0.15 mmol) in tetrahydrofuran (5 ml) . After 30 min, a solution of ethyl vinyl ether (2 g, 0.028 mol) in a mixed solvent of methanol (500 g) and tetrahydrofuran (250 g) was added as a terminator, and the mixture was stirred at room temperature. The reaction solution was added to hexane (20 L) , the precipitate was collected by filtration and the solvent was removed under reduced pressure to give 300 g of poly(5- cyclooctene-1, 2-diol) .

(b) [hydrogenation of poly(5-cyclooctene-l, 2-diol) ]

A solution of poly (5-cyclooctene-l, 2-diol) (300 g) obtained in the above-mentioned (a) in a mixed solvent of tetrahydrofuran (1470 g) and methanol (1230 g) was placed in an autoclave (inner volume 5 L, manufactured by Hastelloy-C) equipped with a pressure gauge, a pop valve, a hydrogen gas introduction tube, a thermometer, a sampling tube and a stirrer under a nitrogen atmosphere, and chlorotris (triphenylphosphine) rhodium (7 g, 7.6 mmol) was added. Then, the atmosphere in the autoclave was substituted 3 times with hydrogen gas, the temperature in the autoclave was raised from room temperature to 60°C over 30 min by an outside heating furnace with stirring at a hydrogen pressure of 5.9 MPa, and the mixture was maintained at the same temperature for 5 hr, during which time hydrogen was supplied to the autoclave to maintain the hydrogen pressure at 5.9 MPa. After cooling to room temperature, the reaction mixture was taken out, added to methanol (3 L) , the precipitated polymer was recovered and the solvent was evaporated under reduced pressure to give hydrogenated poly (5-cyclooctene- 1,2-diol) (290 g) . The molecular weight of the above-mentioned hydrogenated poly(5-cyclooctene-l_/2-diol) was measured using a GPC apparatus (150ALC/GPC manufactured by Waters), a column (HFIP806M manufactured by SHODEX) and a developing solvent of hexafluoroisopropanol, and converted based on standard polymethyl methacrylate. As a result, the number average molecular weight (Mn) was 9,800, and the weight average molecular weight (Mw) was 26,800. It was also found that the hydrogenation degree of the polymer as obtained by 500 MHz ¹H-NMR spectrum (DMSCHd₆ solution, measurement temperature 85°C) was 99.9%. The melting point was 147°C.

The hydrogenated poly (5-cyclooctene-l,2-diol) obtained in Reference Example l(b) was melted in a DSC-light scattering simultaneous measurement apparatus at 190°C, cooled to 145°C at 90°C/min, and maintained at the same temperature for 240 min. Fig. 1 shows the results of DSC measurement by a DSC-light scattering simultaneous measurement apparatus during the above- mentioned period, and Fig. 2 shows the results of light scattering intensity measurement at time points at 30 min intervals during the period of 0-240 min.

In Fig. 1, the transverse axis shows time (min) and the vertical axis shows heat flow (endo down) . From Fig. 1, it was found that crystallization did not proceed during this retention time (0-240 min) because the shift of heat from the sample (hydrogenated poly (5-cyclooctene-l,2-diol) ) to the outside of the system was not observed. In Fig. 2, the transverse axis shows scattering vector (q) and the vertical axis shows strength (a.u) . From Fig. 2, it was found that thermally induced non-equilibrium liquid - liquid phase separation (formation of co-continuous phase separation structure) took place because an exponential increase of the time-course increase in the light scattering intensity was observed. On the other hand, the same thermal history of the hydrogenated poly (5-cyclooctene-l, 2-diol) obtained in the above- mentioned Reference Example 1 (b) as that produced by the above- mentioned DSC-light scattering simultaneous measurement apparatus was reproduced on a temperature-controlable hot stage, and the hydrogenated poly (5-cyclooctene-l, 2-diol) was observed by a confocal scanning laser microscope. Fig. 3 shows the micrograph thereof. From Fig. 3, it was observed that a co-continuous phase separation structure was formed.

The hydrogenated poly (5-cyclooctene-l, 2-diol) obtained in Reference Example 1 (b) was melted at 190°C, cooled to 145°C at 90°C/min, and maintained at the same temperature for 60 min to allow progress of thermally induced non-equilibrium liquid - liquid phase separation, cooled to 100⁰C at 90°C/min, maintained at the same temperature for 60 min to allow sufficient progress of crystallization and cooled to 25°C to give a sample (film having membrane thickness of 200 μm) . The degree of crystallinity of the sample was 50%. The amount of oxygen permeation of the sample was measured and found to be less than

0.3 cc*20 μm/m^2#dayatm. <Example 2>

The hydrogenated poly (5-cyclooctene-l, 2-diol) obtained in Reference Example 1 (b) was melted in a DSC-light scattering simultaneous measurement apparatus at 190⁰C, cooled to 136°C at 90°C/min, and maintained at the same temperature for 120 min. Fig. 4 shows the results of DSC measurement by a DSC-light scattering simultaneous measurement apparatus during the above- mentioned period, and Fig. 5 shows the results of light scattering intensity measurement at time points at 10 min intervals during the period of 0-110 min.

From Fig. 4, it was found that crystallization proceeded during this retention time (0-120 min) because the shift of heat from the sample (hydrogenated poly (5-cyclooctene-l,2-diol) ) to the outside of the system was observed. From Fig. 5, it was found that thermally induced non-equilibrium liquid - liquid phase separation (formation of co-continuous phase separation structure) took place, because an exponential increase of the time-course increase in the light scattering intensity was observed. The increase in the light scattering intensity ended before reaching 60 min. In other words, it was found that the thermally induced non-equilibrium liquid - liquid phase separation completed during the progress of crystallization.

The hydrogenated poly (5-cyclooctene-l,2-diol) obtained in Reference Example 1 (b) was melted at 190°C, cooled to 136°C at 90°C/min, and maintained at the same temperature for 60 min to allow progress of thermally induced non-equilibrium liquid - liquid phase separation, cooled to 100°C at 90°C/min, maintained at the same temperature for 60 min to allow sufficient progress of crystallization and cooled to 25°C to give a sample (film having membrane thickness of 200 μm) . The degree of crystallinity of the sample was 50%. The amount of oxygen permeation of the sample was measured and found to be less than

0.3 cc'20 μm/m²*dayatm. <Comparative Example 1>

The hydrogenated poly (5-cyclooctene-l,2-diol) obtained in Reference Example 1 (b) was melted in a DSC-light scattering simultaneous measurement apparatus, used in the above-mentioned

Example 1, at 190⁰C, cooled to 25°C at 90°C/min, and maintained at the same temperature for 120 min. Fig. 6 shows the results of DSC measurement by a DSC-light scattering simultaneous measurement apparatus during the above-mentioned period, and Fig. 7 shows the results of light scattering intensity measurement at time points at 10 min intervals during the period of 0-120 min. From Fig. 6, it was found that crystallization completed during this retention time (0-40 min) . From Fig. 7, it was found that thermally induced non-equilibrium liquid - liquid phase separation scarcely occurred because time-course increase in the light scattering intensity was scarcely seen.

The hydrogenated poly (5-cyclooctene-l,2-diol) obtained in Reference Example 1 (b) was melted at 190°C on a temperature- controlable hot stage, cooled to 25⁰C at 90°C/min, and maintained at the same temperature for 120 min. Then, the mixture was further heated to 100°C at 90°C/min and maintained at the same temperature for 180 min. The hydrogenated poly (5-cyclooctene- 1,2-diol) after maintaining was observed with a confocal scanning laser microscope. Fig. 8 shows the results thereof and from Fig. 8, it was found that a co-continuous phase separation structure was scarcely formed.

The hydrogenated poly (5-cyclooctene-l,2-diol) obtained in Reference Example 1 (b) was melted at 190⁰C, cooled to 25°C at 90°C/min, and maintained at the same temperature for 60 min, further heated to 100⁰C at 90°C/min, maintained at the same temperature for 60 min to allow sufficient progress of crystallization and cooled to 25°C to give a sample (film having membrane thickness of 200 μm) . The amount of oxygen permeation of the sample was measured and found to be 6 cc*20 μm/m^2#dayatm. Industrial Applicability

As is clear from the foregoing explanation, a gas barrier polymer material showing extremely high gas barrier property can be obtained according to the present invention. The gas barrier polymer material obtained by the present invention has extremely high gas barrier property and fine moldability. Therefore, the material can be used as a packaging material for various products by, for example, forming into a film, a sheet or a container. Particularly, since the material shows extremely high oxygen barrier property over a wide range of from low humidity to high humidity, a gas barrier layer of a metal, a vapor deposition film of silicon oxide and the like is not necessary, whereby a packaging material for food with fine visual observability of the contents can be provided.

Claims

1. A gas barrier polymer material comprising a hydroxyl group- containing gas barrier polymer having a phase separation structure comprising two or more co-continuous regions, which mainly comprises a structural unit represented by the following formula (I)

wherein m and n are each an integer of 0 to 10; X¹ and X² are each a hydrogen atom, a hydroxyl group or a functional group convertible to a hydroxyl group, provided that the total of m and n is not less than 1 and at least one of X¹ and X² is a hydroxyl group or a functional group convertible to a hydroxyl group; R¹, R² and R³ are each a hydrogen atom, a hydroxyl group, a functional group convertible to a hydroxyl group, an alkyl group, an aryl group, an aralkyl group or a heteroaryl group; and R¹, R², R³, X¹ and X² present in plurality are optionally the same as or different from each other.

2. The gas barrier polymer material of claim 1, which shows an amount of oxygen permeation at 2O⁰C, 90% RH of not more than 1 CC20 μm/m²*dayatm.

3. A packaging material comprising a gas barrier polymer material of claim 1 or 2.

4. A production method of a gas barrier polymer material of claim 1, which comprises Step A comprising cooling a molten product of the hydoroxyl group-containing gas barrier polymer or a resin composition comprising the hydroxyl group-containing gas barrier polymer to a temperature within the range of from a temperature lower than the melting point of the hydroxyl group-containing gas barrier polymer by 100°C (Tm-IOO⁰C) to the melting point (Tm⁰C) and retaining the molten product within the aforementioned temperature range for not less than 2 minutes, wherein the hydroxyl group-containing gas barrier polymer mainly comprises a structural unit represented by the following formula (I) :