JP5162438B2 - Gas barrier materials - Google Patents

Description

  The present invention relates to a gas barrier material from which a film having excellent gas barrier properties can be obtained, a gas barrier molded article using the same, and a method for producing the same.

Since current gas barrier materials such as water vapor are mainly produced from fossil resources, they are non-biodegradable and must be incinerated. Therefore, it has been studied to produce a biodegradable oxygen barrier material using reproducible biomass as a raw material.
JP 2001-334600 A JP 2002-348522 A JP 2008-1728 A Bio MACROMOLECULES Volume7, Number6, June 2006, Published by the American Chemical Society

  Patent Document 1 is an invention relating to a gas barrier material using a water-soluble polysaccharide containing polyuronic acid as a raw material, and there is a possibility that the gas barrier property in a high humidity atmosphere is deteriorated. There is also room for improvement in water vapor barrier properties.

  Patent Document 2 is an invention relating to a coating agent containing microcrystalline cellulose and a laminated material in which the coating agent is applied to a substrate. It is described that the microcrystalline cellulose powder as a raw material preferably has an average particle size of 100 μm or less, and in the examples, only those having an average particle size of 3 μm and 100 μm are used. There is no description about the miniaturization treatment, and there is room for improvement in the denseness and film strength of the applied coating agent layer and the adhesion to the substrate.

  Patent Document 3 discloses an invention relating to fine cellulose fibers and describes the possibility of being used as a coating material, but does not describe the use for which a specific effect is shown.

  Non-Patent Document 1 does not disclose any gas barrier properties such as a water vapor barrier.

  An object of the present invention is to provide a gas barrier material capable of obtaining a film having particularly excellent water vapor barrier properties, a gas barrier molded article using the same, and a method for producing the same.

The present invention provides the following inventions as means for solving the problems.
1. A gas barrier material comprising cellulose fibers having an average fiber diameter of 200 nm or less and an oily component that is solid at 25 ° C., wherein the cellulose constituting the cellulose fibers has a carboxyl group content of 0.1 to 2 mmol / g.
2. 2. The gas barrier material according to claim 1, wherein an average aspect ratio of cellulose fibers having an average fiber diameter of 200 nm or less is 10 to 1,000. The gas barrier material according to claim 1 or 2, wherein the oil component that is solid at 25 ° C has a melting point of 30 ° C to 150 ° C.
4). A gas barrier molded article comprising the gas barrier material according to claim 1.
5. The gas barrier property molded object which has a layer containing the gas barrier material of any one of Claims 1-3 in the molded object surface used as a base material.
6). The gas barrier molded article according to claim 4 or 5, wherein a contact angle of the ion exchange water with respect to the gas barrier layer is 20 to 120 °.
7). A suspension containing the gas barrier material according to any one of claims 1 to 3 is supplied to and adhered to a molded body to be a base material or a hard surface for molding to form a film-like material The process of
Thereafter, heating the film-like material at a temperature equal to or higher than the melting point of the solid oily component at 25 ° C.
A method for producing a gas barrier molded article having
8). The method for producing a gas barrier molded article according to claim 7, wherein the suspension containing the gas barrier material is a mixed liquid of a suspension containing the cellulose fibers and an emulsion containing an oily component that is solid at 25 ° C.

  The gas barrier referred to in the present invention refers to a shielding function against various gases such as oxygen, nitrogen, carbon dioxide, organic vapor, and water vapor, and aroma substances such as limonene and menthol.

  By using the gas barrier material of the present invention, a molded body such as a film having particularly high gas barrier properties can be obtained.

<Material for gas barrier>
The gas barrier material of the present invention contains specific cellulose fibers and an oily component that is solid at 25 ° C.
1) Cellulose fiber The cellulose fiber used in the present invention has an average fiber diameter of 200 nm or less, preferably 1 to 200 nm, more preferably 1 to 100 nm, still more preferably 1 to 50 nm. An average fiber diameter is calculated | required by the measuring method as described in an Example.

  The carboxyl group content of cellulose constituting the cellulose fiber used in the present invention is 0.1 to 2 mmol / g, preferably 0.4 to 2 mmol / g, more preferably from the viewpoint of obtaining high gas barrier properties. Is 0.6 to 1.8 mmol / g, more preferably 0.6 to 1.6 mmol / g. Carboxyl group content is calculated | required by the measuring method as described in an Example. When the carboxyl group content is less than 0.1 mmol / g, the average fiber diameter of the cellulose fibers does not become 200 nm or less even when the fiber refining treatment described below is performed, and a gas barrier molded article having good performance is obtained. It becomes difficult.

  The cellulose fiber used in the present invention has a content of carboxyl group of cellulose constituting the cellulose fiber in the above range, but depending on the control state such as oxidation treatment in the actual production process, the cellulose fiber after oxidation treatment What exceeds the said range may be contained in it as an impurity.

  The cellulose fibers used in the present invention have an average aspect ratio of 10 to 1,000, preferably 10 to 500, more preferably 100 to 350. An average aspect ratio is calculated | required by the measuring method as described in an Example.

  The cellulose fiber used by this invention can be manufactured by the following method, for example. First, about 10 to 1000 times the amount (mass basis) of water is added to the raw natural fiber (absolute dry basis), and processed with a mixer or the like to form a slurry.

  Examples of natural fibers that can be used as raw materials include wood pulp, non-wood pulp, cotton, and bacterial cellulose.

  Next, the natural fiber is oxidized using 2,2,6,6, -tetramethyl-1-piperidine-N-oxyl (TEMPO) as a catalyst. In addition, 4-acetamido-TEMPO, 4-carboxy-TEMPO, 4-phosphonooxy-TEMPO and the like, which are derivatives of TEMPO, can be used as the catalyst.

  The amount of TEMPO used is in a range of 0.1 to 10% by mass with respect to natural fibers (absolute dry standard) used as a raw material.

  During the oxidation treatment, an oxidant such as sodium hypochlorite and a bromide such as sodium bromide are used in combination with TEMPO as a co-oxidant.

  As the oxidizing agent, hypohalous acid or a salt thereof, hypohalous acid or a salt thereof, perhalogenic acid or a salt thereof, hydrogen peroxide, a perorganic acid, or the like can be used. Alkali metal hypohalites such as sodium bromite. The amount of the oxidizing agent used is in a range of about 1 to 100% by mass with respect to the natural fiber (absolute dry standard) used as a raw material.

  As a co-oxidant, it is preferable to use an alkali metal bromide such as sodium bromide. The usage-amount of a co-oxidant is the range used as about 1-30 mass% with respect to the natural fiber (absolute dry standard) used as a raw material.

  The pH of the slurry is desirably maintained in the range of 9 to 12 from the viewpoint of allowing the oxidation reaction to proceed efficiently.

  The temperature of the oxidation treatment (temperature of the slurry) is arbitrary at 1 to 50 ° C., but the reaction is possible at room temperature, and temperature control is not particularly required. The reaction time is preferably 1 to 240 minutes.

  After the oxidation treatment, the used catalyst or the like is removed by washing with water or the like. At this stage, since the reaction fiber is not refined, it can be performed by a purification method in which washing and filtration are repeated. If necessary, a dried or fibrous oxidized cellulose can be obtained.

  Thereafter, the oxidized cellulose is dispersed in a solvent such as water and subjected to a fine treatment. Refinement treatment is performed by a disaggregator, a beater, a low-pressure homogenizer, a high-pressure homogenizer, a grinder, a cutter mill, a ball mill, a jet mill, a short-axis extruder, a twin-screw extruder, an ultrasonic stirrer, and a domestic juicer mixer. And can be adjusted to length. The solid concentration in this step is preferably 50% by mass or less. Beyond that, it is not preferable because very high energy is required for dispersion.

  By such refinement treatment, cellulose fibers having an average fiber diameter of 200 nm or less can be obtained, and the average aspect ratio is 10 to 1,000, more preferably 10 to 500, and still more preferably 100 to 350. A certain cellulose fiber can be obtained.

  Thereafter, a suspension of cellulose fibers (a liquid that is visually colorless and transparent or opaque) with a solid content adjusted as necessary, or a cellulose powder that is dried as necessary (provided that the cellulose fibers are agglomerated) And does not mean cellulose particles). In addition, when making into suspension, what used only water may be used, and the mixed solvent of water, other organic solvents (for example, alcohol, such as ethanol), surfactant, an acid, a base, etc. was used. It may be a thing.

  By such oxidation treatment and refinement treatment, the hydroxyl group at the C6 position of the cellulose structural unit is selectively oxidized to a carboxyl group via an aldehyde group, and the carboxyl group content is 0.1 to 2 mmol / g. Highly crystalline cellulose fibers that are made of cellulose and have an average fiber diameter of 200 nm or less can be obtained. This highly crystalline cellulose fiber has a cellulose I-type crystal structure. This means that the cellulose fiber is a fiber that is refined by surface oxidation of a naturally-derived cellulose solid raw material having an I-type crystal structure. In other words, natural cellulose fibers have a high-order solid structure built up by bundling fine fibers called microfibrils produced in the process of biosynthesis. The fine cellulose fiber is obtained by weakening the hydrogen bond) by introducing an aldehyde group or a carboxyl group, and further through a refinement treatment.

  Then, by adjusting the oxidation treatment conditions, the cellulose fiber content can be increased or decreased within a predetermined range, the polarity can be changed, the electrostatic repulsion of the carboxyl group or the above-mentioned fine processing can be applied to cellulose fibers. The average fiber diameter, average fiber length, average aspect ratio, and the like can be controlled.

Cellulose fibers obtained by the above oxidation treatment and refinement treatment can satisfy the following requirements (I), (II), and (III).
(I): The mass fraction of cellulose fibers that can pass through a glass filter having an aperture of 16 μm is 5% or more with respect to the mass of cellulose fibers in the cellulose fiber suspension diluted to a solid content of 0.1 mass%. To obtain cellulose fibers with good performance.
(II): The cellulose fiber suspension diluted to a solid content of 1% by mass does not contain cellulose granules having a particle size of 1 μm or more.
(III): The light transmittance of the cellulose fiber suspension diluted to a solid content of 1% by mass is 0.5% or more.

  Requirement (I): When the suspension having a solid content of 0.1% by mass obtained by the above oxidation treatment and refinement treatment is passed through a glass filter having an aperture of 16 μm, the suspension before passing through the glass filter is suspended. A mass fraction of 5% or more with respect to the total amount of cellulose fibers contained in the suspension can pass through the glass filter (the mass fraction of fine cellulose fibers that can pass through the glass filter is defined as the content of fine cellulose fibers). To do). From the viewpoint of gas barrier properties, the fine cellulose fiber content is preferably 30% or more, more preferably 90% or more.

  Requirement (II): The suspension having a solid content of 1% by mass obtained by the above-described oxidation treatment and refinement treatment has a refined natural fiber used as a raw material, and is a cellulose granule having a particle diameter of 1 μm or more. What does not contain a body is preferable. Here, the granular material is substantially spherical, and the ratio of the major axis to the minor axis (major axis / minor axis) of the rectangle surrounding the projected shape obtained by projecting the shape onto a plane is 3 or less at the maximum. . The particle diameter of the granular material is an arithmetic average value of the lengths of the major axis and the minor axis. The presence / absence of the granular material was determined by observation with an optical microscope described later.

  Requirement (III): The cellulose fiber suspension having a solid content of 1% by mass obtained by the above oxidation treatment and refinement treatment preferably has a light transmittance of 0.5% or more, from the viewpoint of gas barrier properties. More preferably, it is 40% or more, and further preferably 60% or more.

  And, the above-mentioned control produces hydrogen bonds and cross-linking strong interactions between fine cellulose fibers, for example, it is possible to suppress the permeation and diffusion of oxygen molecules and to develop gas barrier properties such as high oxygen barrier properties. It is done. Moreover, since the void density between the cellulose fibers after molding (after film formation) can be changed depending on the width and length of the cellulose fibers (that is, the molecular sieving effect can be changed), a molecular selective barrier is achieved. In addition to expectation, the light transmittance can be controlled.

  Examples of oily components that are solid at 25 ° C. used in the present invention include hydrocarbon-based, aliphatic-based, and silicone-based waxes. For example, selected from microcrystalline wax, paraffin wax, carnauba wax, polyethylene wax, ceresin, low molecular polyolefin, beeswax, candelilla wax, stearic acid, stearyl alcohol, alkyl ketene dimer, alkenyl succinic anhydride resin, silicone wax, etc. Can be mentioned. The form is used in the state of powder, melt, or emulsion, and preferably in the state of emulsion.

  The oily component that is solid at 25 ° C. used in the present invention preferably has a melting point of 30 to 150 ° C. or less, more preferably a melting point of 50 to 100 ° C.

  The gas barrier material of the present invention contains the above-described specific cellulose fiber and an oily component that is solid at 25 ° C. The content ratio of the specific cellulose fiber and the oil component solid at 25 ° C. is preferably 0.5 to 50 parts by mass, more preferably 1.0 to 25 parts by mass with respect to 100 parts by mass of the cellulose fiber. 5 to 15 parts by mass is more preferable.

  The gas barrier material of the present invention can be made into a suspension of cellulose fibers obtained by mixing a suspension containing the above-mentioned specific cellulose fibers and an emulsion containing an oil component that is solid at 25 ° C. Can be dried to form a solid.

  The gas barrier material may be a known filler, colorant such as pigment, ultraviolet absorber, antistatic agent, water-resistant agent (silane coupling agent, etc.) within the range of types and amounts that can solve the problems of the present invention. , Clay minerals (montmorillonite, etc.), crosslinking agents (additives having reactive functional groups such as epoxy groups, isocyanate groups, etc.), metal salts, colloidal silica, alumina sol, titanium oxide and the like can be blended.

<Gas barrier molding>
The gas barrier molded article of the present invention is
(I) What is obtained by molding a gas barrier material without using a base material,
(II) having a layer made of a gas barrier material on the surface of a molded body to be a base material,
Can be either.

  As the molded body serving as the base material, a thin film such as a film, a sheet, a woven fabric, and a non-woven fabric having a desired shape and size, and a three-dimensional container such as a box or bottle having various shapes and sizes can be used. These molded products may be made of paper, paperboard, plastic, metal (a material having a large number of holes or a wire mesh, which is mainly used as a reinforcing material), or a composite of these. Among them, it is preferable to use plant-derived materials such as paper and paperboard, biodegradable materials such as biodegradable plastics, or biomass-derived materials. The molded body serving as the base material can have a multilayer structure made of a combination of the same or different materials (for example, adhesiveness and wettability improver).

  The plastic used as the base material can be appropriately selected according to the application, but polyolefins such as polyethylene and polypropylene, polyamides such as nylon 6, 66, 6/10, and 6/12, polyethylene terephthalate (PET), and polybutylene. One or more selected from polyesters such as terephthalate, aliphatic polyester, polylactic acid (PLA), polycaprolactone, and polybutylene succinate, cellophane such as cellulose, and cellulose triacetate (TAC) can be used.

  The thickness of the molded body serving as the base material is not particularly limited, and may be appropriately selected so that strength according to the application can be obtained. For example, the thickness can be in the range of 1 to 1000 μm.

  The thickness of the layer made of the gas barrier material (gas barrier layer) is not particularly limited, and may be appropriately selected so as to obtain gas barrier properties according to the application. For example, the thickness may be in the range of 20 to 5000 nm. it can.

<Method for producing gas barrier molded article>
When the gas barrier molded product does not include a molded product as a base material, the gas barrier material is cast on a substrate such as a glass plate and then dried by a drying method such as natural drying or air drying. To form a film. Thereafter, the film is peeled off from the substrate to obtain the gas barrier molded article (gas barrier film) of the present invention.

  In the case of forming a layer made of a gas barrier material on the surface of a molded body to be a base material, for example, on one side or both sides of the base material, preferably by a known method such as a coating method, a spray method, a dipping method, etc. A gas barrier material (base material + gas barrier layer) is obtained by attaching a gas barrier material by a coating method or a spraying method, and then drying by a method such as natural drying or blow drying.

  The gas barrier material used in this step is a suspension of cellulose fibers obtained by mixing a suspension containing the specific cellulose fibers and an emulsion containing an oily component that is solid at 25 ° C. The concentration of the specific cellulose fiber in the suspension is preferably about 0.05 to 30% by mass, and more preferably 0.5 to 5% by mass.

  In the next step, the gas barrier molded body formed in the previous step is heat-treated at a temperature equal to or higher than the melting point of the solid oil component at 25 ° C. contained in the gas barrier material.

  The heating temperature is preferably in the temperature range of 10 to 150 ° C. higher than the melting point of the solid oily component at 25 ° C., more preferably 30 to 100 ° C. If the heating temperature is low, heating takes too much time, and if the heating temperature is too high, there is a problem of deformation (for example, shrinkage or curling) or alteration (for example, thermal decomposition) of the base material or the barrier layer. What is necessary is just to select a heating time suitably in the range which can melt | dissolve a solid oil-based component at 25 degreeC, and a deformation | transformation and quality change of a base material or a barrier layer do not occur, for example, can be set as the range for 1 to 120 minutes.

  By this heat treatment, the gas barrier property can be improved as compared with the case where the heat treatment is not performed. Although the detailed mechanism of such gas barrier property improvement is unclear, the solid oily component is once softened at 25 ° C. contained in the gas barrier layer and fused together to form a continuous phase of solid oil. This is presumed.

  The contact angle between the gas barrier layer surface of the gas barrier molded article of the present invention and ion-exchanged water is the content of carboxyl groups in cellulose fibers, the type of oily components that are solid at 25 ° C, and the amount of oily components that are solid at 25 ° C. Although it can adjust with heating temperature and heating time, it is preferable that the contact angle is 20-120 degrees, More preferably, it is 30-110 degrees.

  The gas barrier molded article of the present invention is suitable as a packaging material in various fields where water vapor barrier properties, oxygen barrier properties and the like are required.

  Each measuring method in the examples is as follows.

(1) Properties of Cellulose Fiber Suspension (1-1) Light Transmittance Using a spectrophotometer (UV-2550, manufactured by Shimadzu Corporation), a suspension having a concentration of 1% by weight has a wavelength of 660 nm and an optical path length of 1 cm. The light transmittance (%) was measured.

(1-2) Mass fraction of fine cellulose fiber in cellulose fiber suspension (fine cellulose fiber content) (%)
A cellulose fiber suspension was prepared to 0.1% by mass, and its solid content concentration was measured. Subsequently, the cellulose fiber suspension was subjected to suction filtration with a glass filter having a mesh size of 16 μm (25GP16, manufactured by SHIBATA), and then the solid content concentration of the filtrate was measured. The (C1 / C2) value obtained by dividing the solid content concentration (C1) of the filtrate by the solid content concentration (C2) of the suspension before filtration was calculated as the fine cellulose fiber content (%).

(1-3) Observation of suspension One drop of the suspension diluted to a solid content of 1% by mass was dropped on a slide glass, and a cover glass was placed on it to prepare an observation sample. Arbitrary five places of this observation sample were observed with an optical microscope (manufactured by ECLIPSE E600 POL NIKON) at a magnification of 400 times to confirm the presence or absence of cellulose granules having a particle diameter of 1 μm or more. The granular material is substantially spherical, and the ratio of the major axis to the minor axis (major axis / minor axis) of the rectangle surrounding the projected shape obtained by projecting the shape onto a plane is 3 or less at the maximum. The particle diameter of the granular material is an arithmetic average value of the lengths of the major axis and the minor axis. At this time, it can be confirmed more clearly by crossed Nicols observation.

(2) Cellulose fiber (2-1) Average fiber diameter and average aspect ratio The average fiber diameter of the cellulose fiber was obtained by dropping a suspension diluted to 0.0001% by mass onto mica and drying it as an observation sample. The fiber height was measured with an atomic force microscope (Nanoscope III Tapping mode AFM, manufactured by Digital instrument, probe using Point Probe (NCH) manufactured by Nano Sensors). In an image in which cellulose fibers can be confirmed, five or more were extracted, and the average fiber diameter was determined from the fiber height.

  The average aspect ratio was calculated from the viscosity of a diluted suspension (0.005 to 0.04% by mass) obtained by diluting cellulose fibers with water. The viscosity was measured at 20 ° C. using a rheometer (MCR300, DG42 (double cylinder), manufactured by PHYSICA). From the relationship between the mass concentration of the cellulose fiber and the specific viscosity of the cellulose fiber suspension with respect to water, the aspect ratio of the cellulose fiber was calculated by the following formula to obtain the average aspect ratio of the cellulose fiber.

(The theory of Polymer Dynamics, M.DOI and DFEDWARDS, CLARENDON PRESS / OXFORD, 1986, P312) The viscosity formula (8.138) of a rigid rod-like molecule was used (here, rigid rod-like molecule = cellulose fiber) ). (8.138) equation and _{^{Lb 2 × ρ 0 = M /}} N equation 1 from the relation of _a is derived. here, eta _sp is specific viscosity, [pi is circle ratio, ln is natural logarithm, P Is the aspect ratio (L / b), γ = 0.8, ρ _s is the density of the dispersion medium (kg / m ³ ), ρ ₀ is the density of cellulose crystals (kg / m ³ ), and C is the mass concentration of cellulose (C = ρ / ρ _s ), L is the fiber length, b is the fiber width (the cross section of the cellulose fiber is square), ρ is the concentration of the cellulose fiber (kg / m ³ ), M is the molecular weight, and N _A is the Avogadro number. )
(2-2) Carboxyl group content (mmol / g)
About 0.5 g of the dry weight of oxidized pulp is put in a 100 ml beaker, and ion exchange water is added to make a total of 55 ml. Then, 5 ml of 0.01 M sodium chloride aqueous solution is added to prepare a pulp suspension. Stir with a stirrer until dispersed. Then, 0.1M hydrochloric acid is added to adjust the pH to 2.5 to 3.0, and then 0.05M sodium hydroxide aqueous solution is injected under the condition of a waiting time of 60 seconds using an automatic titrator (AUT-501, manufactured by Toa DK Corporation). Then, the electric conductivity and the pH value of the pulp suspension every minute were measured, and the measurement was continued until the pH became about pH11. And the sodium hydroxide titration amount was calculated | required from the obtained electrical conductivity curve, and carboxyl group content was computed. Natural cellulose fibers exist as aggregates of highly crystalline microfibrils formed by collecting about 20 to 1500 cellulose molecules. In the TEMPO oxidation reaction employed in the present invention, a carboxyl group can be selectively introduced onto the surface of the crystalline microfibril. Therefore, in reality, carboxyl groups are introduced only on the crystal surface, but the carboxyl group content defined by the measurement method is an average value per cellulose weight.

(3) Measurement of average particle diameter of wax emulsion The particle diameter of the wax emulsion was measured using a laser diffraction particle size distribution analyzer (SALD-300V, manufactured by Shimadzu Corporation).

(4) Measurement of Melting Point of Wax The melting point of wax was measured using a suggestion scanning calorimeter (manufactured by Seiko Denshi Kogyo Co., Ltd .: DSC220) at a temperature rising rate of 2 ° C./min.

(5) Contact angle on the gas barrier layer surface After about 1 μl of ion-exchanged water is dropped on the gas barrier layer surface of the gas barrier film, the contact angle after 10 seconds is measured using an interfacial tension measuring instrument (manufactured by Kyowa Interface Science Co., Ltd., FAMAS). The measurement was performed under conditions of 20 ° C. and 50% RH.

(6) Water vapor permeability (g / m ² · day)
Based on JIS Z0208, the measurement was performed under conditions of an environment of 40 ° C. and 90% RH using a cup method.

(7) Oxygen permeability (differential pressure method) (cm ³ / m ² · day · Pa)
Based on the ASTM D-1434-75M method, a gas permeation measuring device (model M-C3, manufactured by Toyo Seiki Seisakusho Co., Ltd.) was used, and the sample was measured under the condition of 23 ° C. after being evacuated for 24 hours.

Production Example 1 (Production of specific cellulose fiber)
(I) Raw material, catalyst, oxidizing agent, co-oxidant Natural fiber: Bleached kraft pulp of conifers (Manufacturer: Fletcher Challenge Canada, trade name “Machenzie”, CSF 650 ml)
TEMPO: Commercial product (Manufacturer: ALDRICH, Free radical, 98%)
Sodium hypochlorite: Commercial product (Manufacturer: Wako Pure Chemical Industries, Ltd. Cl: 5%)
Sodium bromide: Commercial product (manufacturer: Wako Pure Chemical Industries, Ltd.).

(II) Production procedure First, 100 g of bleached kraft pulp fiber of the above-mentioned coniferous tree was sufficiently stirred with 9900 g of ion-exchanged water, and then TEMPO 1.25% by mass, sodium bromide 12.5% by mass, hypoxia with respect to 100 g of pulp mass. Sodium chlorate (28.4% by mass) was added in this order, and a pH stud was used to maintain the pH at 10.5 by dropwise addition of 0.5M sodium hydroxide, and an oxidation reaction was performed at a temperature of 20 ° C. The dripping was stopped at an oxidation time of 120 minutes to obtain oxidized pulp.

  Next, the oxidized pulp was sufficiently washed with ion-exchanged water and dehydrated. Thereafter, 100 g of oxidized pulp and 9900 g of ion-exchanged water are stirred for 120 minutes with a mixer (Vita-Mix-Blender ABSOLUTE, manufactured by Osaka Chemical Co., Ltd.), thereby performing fiber refining treatment, and transparent cellulose fibers. A suspension was obtained. The obtained cellulose fiber had a carboxyl group content of 1.2 mmol / g, an average fiber diameter of 3.1 nm, and an average aspect ratio of 240. The resulting suspension had a solid content concentration of 1.5% by mass, a light transmittance of 97.1%, and a fine cellulose content of 90.9%. The suspension did not contain cellulose granules having a particle size of 1 μm or more.

Examples 1-5,
The suspension of cellulose fibers obtained in Production Example 1 and a wax emulsion (solid content concentration: 1.0% by mass) were mixed. As the wax emulsion, trade name: Cerozol 524 (manufactured by Chukyo Yushi, main component carnauba wax, melting point 82.5 ° C., average particle size 0.167 μm), trade name: Cellozol H620 (manufactured by Chukyo Yushi, main component paraffin wax, melting point) 67.4 ° C., average particle diameter 0.3 μm), trade name: AD1602 (manufactured by Starlight PMC, alkyl ketene dimer, melting point 61.3 ° C., average particle diameter 0.329 μm) was used. A suspension of cellulose fibers and a wax emulsion were mixed so that the solid content ratio of cellulose fibers and wax was as shown in Table 1 to obtain a gas barrier material.

  Next, a polylactic acid (PLA) sheet (corona discharge-treated product, sheet thickness 25 μm, trade name PG Pal Green LC-4: manufactured by Tosero Co., Ltd.) or polyethylene terephthalate (PET) sheet (trade name: Lumirror, Toray Industries, Inc.) The gas barrier material was applied by bar coating on one side of a sheet having a sheet thickness of 7 μm and dried at 23 ° C. for 6 hours or longer to obtain a gas barrier molded article of the present invention.

  Thereafter, the dried gas barrier molded body was heated in a constant temperature drying oven (natural convection) at 105 ° C. and 150 ° C. for 30 minutes to obtain a heat-treated gas barrier molded body of the present invention.

  Comparative Example 1 is a polylactic acid (PLA) sheet (corona discharge-treated product, sheet thickness 25 μm, trade name PG Pal Green LC-4: manufactured by Tosero Co., Ltd.). In Comparative Example 2, the cellulose fiber suspension of Production Example 1 (excluding wax) was applied to the sheet of Comparative Example 1 with a bar coat, and then dried at 23 ° C. for 6 hours or more. Comparative Example 3 is a polyethylene terephthalate (PET) sheet (trade name: Lumirror, manufactured by Toray Industries, Inc., sheet thickness: 7 μm). In Comparative Example 4, the cellulose fiber suspension of Production Example 1 (excluding wax) was applied to the sheet of Comparative Example 3 by bar coating, and then dried at 23 ° C. for 6 hours or more.

As is apparent from comparison between Examples 1, 2, 3, and 4 and Comparative Example 1 and Example 5 and Comparative Example 3, the gas barrier molded article of the present invention has improved water vapor barrier properties and oxygen barrier properties. Further, when Examples 1, 2, and 4 are compared with Comparative Example 2 and Example 5 and Comparative Example 4 are compared, the barrier molded article of the present invention has a wax content of 10% by mass in the gas barrier layer. Regardless of the type, the water vapor barrier property was improved while maintaining the oxygen barrier property equivalent to the sheet coated only with the cellulose fiber suspension. Furthermore, oxygen barrier property and water vapor | steam barrier property improved by adding heat processing. In particular, when heated at a temperature 30 ° C. higher than the melting point of the wax, the oxygen barrier property and the water vapor barrier property were remarkably improved. When Example 3 and Comparative Example 2 are compared, when the wax in the gas barrier layer is 30% by mass, the oxygen barrier property is lower than that of the sheet coated only with the cellulose fiber suspension, but by heat treatment The water vapor barrier property was improved.
When attention is paid to the contact angle on the surface of the gas barrier layer of the example, when the contact angle is 30 ° or more, the oxygen barrier property and the water vapor barrier property are improved.

Claims (8)

  A gas barrier material comprising cellulose fibers having an average fiber diameter of 200 nm or less and an oily component that is solid at 25 ° C., wherein the cellulose constituting the cellulose fibers has a carboxyl group content of 0.1 to 2 mmol / g.   The gas barrier material according to claim 1, wherein an average aspect ratio of cellulose fibers having an average fiber diameter of 200 nm or less is 10 to 1,000.   The gas barrier material according to claim 1 or 2, wherein the oil component that is solid at 25 ° C has a melting point of 30 ° C to 150 ° C.   A gas barrier molded article comprising the gas barrier material according to claim 1.   The gas barrier property molded object which has a layer containing the gas barrier material of any one of Claims 1-3 in the molded object surface used as a base material.   The gas barrier molded article according to claim 4 or 5, wherein a contact angle of the ion exchange water with respect to the gas barrier layer is 20 to 120 °. A suspension containing the gas barrier material according to any one of claims 1 to 3 is supplied to and adhered to a molded body to be a base material or a hard surface for molding to form a film-like material The process of
Thereafter, heating the film-like material at a temperature equal to or higher than the melting point of the solid oily component at 25 ° C.
A method for producing a gas barrier molded article having   The method for producing a gas barrier molded article according to claim 7, wherein the suspension containing the gas barrier material is a mixed liquid of a suspension containing the cellulose fibers and an emulsion containing an oily component that is solid at 25 ° C.