JP2019151681A - Lignin clay composite film and method for producing the same - Google Patents

Abstract

To provide a lignin clay composite film that contains lignin and clay mineral, and can have excellent ultraviolet absorption properties or the like.SOLUTION: A lignin clay composite film contains lignin and clay mineral, and has an incombustibility corresponding to V-0 in vertical combustion test UL94 and shows 90% or more ultraviolet absorption properties at 400 nm. The lignin used herein is low modified lignin with a yield of an aromatic compound monomer, obtained by alkaline nitrobenzene oxidation reaction, of 15% or more.SELECTED DRAWING: None

Description

  The present invention relates to a lignin clay composite film and a method for producing the same.

  A clay film formed by molding a specific clay material into a film and then heat-treating it is a functional material having various functions including gas barrier properties (Patent Document 1). However, these clay films have difficulty in combustibility due to the low heat resistance of the organic polymer serving as a clay binder. Aromatic polymer lignin, which is a plant biomass, is expected to be a binder that gives heat resistance because of its excellent heat resistance, but conventional lignin has a deep black color so that the transparency of the film is lost (Non-patent Document 1). ). Further, since a third component other than clay and lignin is required for film formation, it is difficult to impart nonflammability. Furthermore, since the conventional light-transmitting clay film allows light in the ultraviolet region (400 nm or less) to pass through, it cannot play a role as ultraviolet protection (Non-Patent Document 2).

  On the other hand, the cell wall component which is the main component of the plant-based material is mainly composed of cellulose, hemicellulose, and lignin. Since these three components are complexly bound to each other in the cell wall, it is not easy to separate them as they are. Several cell wall component separation technologies have been developed and carried out in the field of paper and pulp production. In these methods, component separation is performed under extremely strong reaction conditions such as acid, alkali, or high temperature. Although hemicellulose can be obtained satisfactorily, lignin is significantly modified. Under such circumstances, as a technique for extracting low-denatured lignin from cell wall components without using a strong acid or strong alkali at 60 ° C. or lower, a plant raw material is wet-ground in the presence of a saccharifying enzyme, and the pulverized product. It is known from Patent Document 2 and Non-Patent Document 3 that solid-liquid separation is performed to obtain low-denatured lignin.

JP 2008-247695 A JP 2011-92151 A

Adv. Mater., 2017, 29, 1606512 Adv. Mater., 2007, 19, 2450 Green. Chem., 2016, 18, 5962

  An object of the present invention is to provide a lignin clay composite film that contains lignin and a clay mineral and can have excellent ultraviolet absorption characteristics while maintaining translucency.

In order to solve the above problems, the present invention provides the following inventions.
(1) A low-modified lignin having a yield of aromatic compound monomer obtained by alkaline nitrobenzene oxidation reaction of 15% or more and a clay mineral, nonflammability equivalent to vertical combustion test UL94 V-0, and 90 at 400 nm A lignin clay composite film having an ultraviolet absorption property of at least%.
(2) The lignin clay composite film according to (1), wherein the film thickness is 3 to 100 μm.
(3) The lignin clay composite film according to the above (1) or (2), wherein the mass ratio of the low-modified lignin and the clay mineral is 5 parts by mass: 95 parts by mass to 40 parts by mass: 60 parts by mass.
(4) A plant raw material containing cellulose, hemicellulose and lignin is wet pulverized in the presence of cellulose and hemicellulose saccharifying enzyme to obtain a pulverized product, and the pulverized product is subjected to an nitrobenzene oxidation reaction with a liquid component containing a saccharide. The resulting aromatic compound monomer is solid-liquid separated into a solid component containing low-modified lignin having a yield of 15% or more, and then mixed on the support after mixing the solid component dispersion and clay mineral. And drying to produce a lignin clay composite film containing low-denatured lignin and clay mineral, having a nonflammability equivalent to the vertical combustion test UL94 V-0 and an ultraviolet absorption property of 90% or more at 400 nm. A method for producing a lignin clay composite film.
(5) The manufacturing method of the lignin clay composite film as described in said (4) whose film thickness is 3-100 micrometers.
(6) The manufacturing method of the lignin clay composite film as described in said (4) or (5) whose mass ratio of low modified | denatured lignin and a clay mineral is 5 mass parts: 95 mass parts-40 mass parts: 60 mass parts.
(7) The method for producing a lignin clay composite film according to any one of the above (4) to (6), wherein the lignin clay composite film is heat-treated at 100 to 200 ° C. to make it water resistant.

  The present invention can provide a lignin clay composite film having excellent nonflammability and ultraviolet absorption characteristics while maintaining translucency. A functional membrane can be obtained only by plant components and clay minerals without using petroleum-derived components, and can impart moisture permeability, gas permeability, and proton conductivity in addition to excellent nonflammability and ultraviolet absorption ability.

  The lignin clay composite film of the present invention contains lignin and a clay mineral and has an ultraviolet absorption property of 90% or more at 400 nm.

  As the lignin, low-modified lignin is used in which the yield of the aromatic compound monomer obtained by the alkaline nitrobenzene oxidation reaction is 15% or more. For example, when lignin is derived from a conifer, the nitrobenzene oxidative degradation rate may be, for example, 15% or more, 18% or more, 20% or more, 22% or more, 25% or more, or 27% or more. When lignin is derived from hardwood, the nitrobenzene oxidative degradation rate is, for example, 15% or more, 18% or more, 20% or more, 22% or more, 25% or more, 27% or more, 30% or more, 35% or more , 40% or more, 45% or 50% or more.

  The plant-based raw material used as the raw material for lignin is not particularly limited, and is a plant-based biomass containing cellulose, hemicellulose and lignin as cell wall components. Wood or herbs such as rice straw, bagasse and bamboo are used.

  These plant-based materials are preferably wet pulverized (ie, saccharified pulverized) in the presence of a saccharifying enzyme, and are preferably coarsely pulverized to 5 mm or less in advance before wet pulverization. For the coarse pulverization, a known pulverizer such as a cutter mill, a chipper, or a rotary cutter can be used.

  The saccharifying enzyme is an enzyme that saccharifies cellulose, hemicellulose and the like contained in the cell wall of the plant-based raw material, and examples thereof include cellulase, hemicellulase, and pectinase. It is preferable to use cellulase and hemicellulase in combination. The amount of saccharifying enzyme used at the time of wet pulverization is not particularly limited, and can be appropriately set according to the amount of plant raw material used.

  Cellulase is an enzyme that hydrolyzes the glucoside bond of β-1,4-glucan, an endoglucanase that cleaves from the inside of the cellulose molecule and an exoglucanase that breaks down from the reducing or non-reducing end of cellulose to release cellobiose, Furthermore, it is an enzyme containing β-glucosidase that cleaves the glucoside bond of cellobiose and converts it into glucose. Hemicellulase is an enzyme that degrades polysaccharides other than cellulose and pectin among the polysaccharides that constitute the cell wall of the plant body. Pectinase is a polygalacturonase, pectin lyase having a catalytic function for degrading pectin, Enzymes such as pectin esterase and pectin methyl esterase. At the time of wet pulverization, for example, an enzyme such as a proteolytic enzyme may be used in addition to the saccharifying enzyme.

  The wet pulverization is pulverization in a slurry state in which an object to be pulverized is suspended in a liquid. For example, a ball mill or a bead mill can be used.

  The liquid used for the wet pulverization is not limited as long as it can hold the object to be pulverized in a slurry state without inactivating the saccharifying enzyme, and preferably includes water and an organic solvent such as alcohol.

  The conditions for wet pulverization are as follows: medium pH 2.0 to 11.0, mass ratio of medium to pulverized object 1: 1 to 100: 1, pulverizer bead diameter 0.1 to 20 mm, bead peripheral speed 0.3 to 50 m / sec, slurry flow rate 0.1 ~ 10L / min, vessel temperature can be selected as appropriate within the range of 0-100 ° C, and measure the particle size and slurry viscosity of the pulverized material over time, for example, preferably when the average particle size is 1μm or less Can do.

  After completion of the wet pulverization, the obtained pulverized product is solid-liquid separated into a liquid component containing saccharide and a solid component containing low-denatured lignin by solid-liquid separation means such as centrifugation. The amount of saccharide eluted in the obtained liquid component is measured by a known method such as the Somogy Nelson method. If the degree of saccharification is not sufficient, a buffer solution and an enzyme are added to the solid component as required, The saccharification may be further promoted by stirring the mixture.

  The solid component obtained by solid-liquid separation can be washed with water and dried to obtain low-denatured lignin. The resulting low-denatured lignin retains better β-ether bonds and has fewer condensed carbon-carbon bonds than lignin obtained by existing extraction methods. It is possible to obtain a low molecular weight satisfactorily by performing a selective lignin decomposition reaction, and to obtain an aromatic compound monomer such as vanillin, vanillic acid, syringaldehyde, or syringic acid with high efficiency.

  Alkaline nitrobenzene oxidation is a decomposition method proposed by Freudenberg, Germany, in 1939. Decomposition can yield about 20 to 28% monomeric aromatic compounds from coniferous lignin and about 50% at most from hardwood lignin. Is the method. Add wood flour or lignin to an aqueous solution previously made alkaline with a reagent such as sodium hydroxide, add nitrobenzene in an amount equivalent to 0.1 to 2.0 times the amount of lignin, and add 1 at an arbitrary temperature of 100 to 200 ° C in an autoclave. It is a decomposition method of heating with stirring for 3 hours.

  In the present invention, the low-denatured lignin is obtained from a solid component obtained by saccharifying cellulose and hemicellulose contained in a cell wall of a plant-based raw material with a saccharifying enzyme as described above, and is subjected to alkaline nitrobenzene under the conditions described in Examples described later. The aromatic compound monomer obtained by the oxidation reaction has a yield of 15% or more.

  After mixing the solid component dispersion and the clay mineral, the obtained uniform dispersion was applied onto the support, dried and peeled off from the support, and contained low-modified lignin and clay mineral, and the vertical combustion test UL94 V- A lignin clay composite film having non-combustibility equivalent to 0 and ultraviolet absorption characteristics of 90% or more at 400 nm can be produced. Water is preferably used as the dispersion medium. The obtained lignin clay composite film behaves as a free-standing film even if it is peeled off from the support.

  As clay minerals, natural or synthetic materials, preferably, for example, bentonite, mica, vermiculite, montmorillonite, beidellite, saponite, hectorite, stevensite, magadiite, illite, kanemite, illite, sericite, and mixtures thereof Is mentioned. These clay minerals are more preferably used by exchanging the interlayer ions with lithium ions, protons, ammonium ions, or the like.

  The mass ratio of lignin and clay mineral is preferably selected from 5 parts by mass: 95 parts by mass to 40 parts by mass: 60 parts by mass.

  It is preferable to forcibly stir the mixed liquid composed of lignin and clay mineral to produce a uniform dispersion. The method for obtaining a uniform dispersion is not particularly limited as long as it can vigorously stir, and includes a stirrer equipped with a stirrer, a shaker stirrer, a homogenizer, and the like. In order to eliminate this, a method using a homogenizer at the final stage of dispersion is preferable. When lumps remain in the dispersion, it can be made a uniform dispersion by filtering the dispersion with a filter. Next, the dispersion is degassed as necessary. Examples of the deaeration process include evacuation, heating, and centrifugation, but a method including evacuation is more preferable. The steps of dispersing, filtering and defoaming may be repeated once or a plurality of times.

  Next, the dispersion is applied to the support surface with a constant thickness. Application can be by casting, baker application, and the like. Next, the dispersion medium is slowly evaporated, and the remainder is formed into a film. As the support, fluororesin, polyethylene terephthalate resin, glass and the like are preferably used. The film-like solid thus formed is preferably dried by, for example, any one of vacuum drying, freeze vacuum drying and heat evaporation, or a combination of these methods.

  Furthermore, by heating the obtained membranous solid, water resistance is imparted and translucent (for example, total light transmittance of 56%) can be exhibited. This heating is usually performed at 100 to 200 ° C. for about 30 minutes to 3 hours.

  The film thickness of the lignin clay composite film of the present invention can be selected depending on the application, but is usually 3 to 100 μm, preferably 10 to 50 μm.

  The lignin clay composite membrane of the present invention can be used as a self-supporting membrane separated from a support, and can be easily cut into an arbitrary size and shape with scissors, a cutter or the like.

  The lignin clay composite film of the present invention is a functional film composed of a plant-derived aromatic polymer, which is a low-denatured lignin, and a clay mineral. In addition to excellent ultraviolet absorbing ability, it has nonflammability and water resistance. It has high moisture permeability and oxygen gas permeability because it has a porous structure. In addition, it retains 10% by weight or more of free water and has proton conductivity because it has ions derived from clay.

  EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited at all by these Examples.

Reference example <Preparation of low-denatured lignin>
Cedar or rice straw was pulverized to about 0.02 to 5 mm by a cutter mill or a jet mill to obtain a plant powder. Immerse 500 g of plant flour in 4.5 L of 100 mM phosphate buffer (pH = 5.0) overnight, and then add it to the wet pulverizer LMZ4 (Ashizawa Finetech) together with the buffer solution. The cellulase / hemicellulase mixture solution (OptimashXL and OptimashBG, 50 mL each) was added, and wet grinding was started while maintaining the temperature at 50 ° C. The beads used for LMZ4 were 0.5 mm diameter made of zirconia metal. After the plant powder was put into LMZ4, the particle size of the wood flour was measured, and when the average particle size reached 10 μm, the beads were replaced with a 0.1 mm diameter, and wet grinding was performed for a total of 4 hours. As the wet milling proceeded, the viscosity of the vegetable powder suspension decreased. The average primary particle size of the obtained powder was 30 to 40 nm.

  After completion of the pulverization, the supernatant and the residue were separated by centrifugation. The sugar in the supernatant was quantified by the Somogie Nelson method. After the residue was washed with water, a saccharification reaction was performed by adding a cellulase / hemicellulase mixture and 1 L of phosphate buffer to the residue and stirring at 50 ° C. for 12 hours. After completion of the reaction, the supernatant and the residue were separated by centrifugation, and lignin (low-denatured lignin) was obtained as the residue. The amount of sugar was quantified in the same manner for the obtained supernatant. The total amount of sugar in the obtained supernatant was about 83%. It was confirmed that about 83% of cellulose and hemicellulose contained in the plant powder were decomposed and eluted into the supernatant as sugar.

<Measurement of nitrobenzene oxidative degradation rate>
100 mg of air-dried low-denatured lignin powder, 7 mL of 1 N NaOH solution, and 0.4 mL of nitrobenzene were placed in a 10 mL stainless steel autoclave and reacted at 170 ° C. with stirring for 2.5 hours. After completion of the reaction, 15 mg of p-hydroxybenzoic acid was added as an internal standard. Extraction was performed three times with an equal amount of diethyl ether to remove nitrobenzene and side reactions aniline and azobenzene. Hydrochloric acid was added to the remaining aqueous layer to adjust to pH 1.0, and then extracted again with an equal amount of diethyl ether three times. The obtained extract was dried under reduced pressure to obtain an aromatic compound produced from low-denatured lignin. The obtained aromatic compound was dissolved in a 10 mM phosphoric acid solution containing 10% acetonitrile, and the produced aromatic compound was qualitatively and quantitatively analyzed by high performance liquid chromatography. As an aromatic compound, 20.926 mg of vanillin, 1.72 mg of vanillic acid, and 1.87 mg of syringaldehyde were obtained, and a monomeric aromatic compound was obtained in a proportion of 24.5% from the low-denatured lignin used. That is, the nitrobenzene oxidative degradation rate of the low-denatured lignin was 24.5%. On the other hand, when sulfite lignin and kraft lignin obtained in the conventional pulp production process were similarly measured for the nitrobenzene oxidative degradation rate, they were 7 to 11%.

<Preparation of low-denatured lignin ultrapure water dispersion>
The low-denatured lignin obtained by the above method was washed in the following steps in order to remove impurities such as buffers and enzymes. About the simultaneous enzymatic saccharification and grinding residue containing low-denatured lignin, the supernatant was removed and dispersed in ultrapure water one or two times by centrifugation at 21000 xg for 90 minutes, and low-denatured lignin ultrapure water dispersion A liquid was obtained. The low-denatured lignin ultrapure water dispersion was 7 to 10% by weight and was a uniform dispersion that did not settle for half a year in a refrigerated state. Thermal mass spectrometry of dried cedar-derived lignin or rice straw-derived lignin using TG-8120 made by Rigaku showed a mass loss of 11% to 13% by heating up to 200 ° C. It was thought to be derived from desorption of attached water.

Example 1 <Preparation of Clay Mineral-Low-Modified Lignin Composite Film>
Add ultrapure water (105.4 g) to a gel-like dispersion (20 wt%; 40 g) of lithium exchange-type purified bentonite (“Kunipia M”: Kunimine Kogyo Co., Ltd.) and use a homogenizer at 6000 rpm for 15 minutes. Mixed. After mixing, a cedar-derived low-denatured lignin ultrapure water dispersion (3.5 wt%; 57.1 g) was added, and the mixture was mixed with a homogenizer at 6000 rpm for 25 minutes. After mixing, the mixture was air-cooled by standing for 30 minutes, and mixed in a rotating / revolving mixer under a mixing mode of 2000 rpm for 5 minutes. Thereafter, the obtained dispersion was passed through a sieve having an opening of 53 μm, and mixed in a rotating / revolving mixer under a mixing mode of 2000 rpm for 2 minutes. Further, the mixture was mixed in a defoaming mode at 2200 rpm for 10 minutes with a rotating and rotating mixer. The finally obtained dispersion was placed on a PET (polyethylene terephthalate) sheet and stretched using a casting knife. At this time, the clearance of the casting knife was 0.6 mm. The stretched dispersion was dried at room temperature. After drying, the membrane was separated from the PET sheet and heated in an electric furnace at 150 ° C. for 2 hours. By this heat treatment, a clay mineral-low-modified lignin composite film having a film thickness of 24 μm was obtained. The ratio of “Kunipia M” and cedar-derived low-denatured lignin in the composite membrane was “Kunipia M”: Low-denatured lignin = 80 wt%: 20 wt%.

  The obtained film retained the form before heating, and was a film having flexibility and handling properties. When the total light transmittance and haze value of the clay mineral-cedar-derived low-modified lignin composite film were evaluated by Nippon Denshoku Industries HAZE METER (NDH5000), they were 56% and 41%, respectively.

  The resulting film was measured for ultraviolet-visible absorption spectrum with a spectrophotometer (HITACHI U-2910), and the transmittance for each wavelength was evaluated. The transmittance at 400 nm was 9.6%, and the ultraviolet region below that ( Even at 400 nm or less, it was 10% or less. The π-conjugate derived from the aromatic network structure of lignin is considered to absorb light in the ultraviolet wavelength region.

  When the obtained film was subjected to thermal mass spectrometry using TG-8120 manufactured by Rigaku, the mass loss by heating up to 200 ° C was 8.7% by weight, which is considered to be derived from desorption of adhering water. It was.

Further, the water vapor permeability of the obtained film was measured by a cup method (moisture permeability test method for moisture-proof packaging material; JIS K 8123). The permeability at a measurement time of 24 hours was 873 g / m ² / day.

In addition, the membrane obtained was evaluated for oxygen permeability by the Mocon method (plastic-film and sheet-gas permeability test method-part 2: isobarometric method; JIS K 7126-2: 2006). According to the oxygen gas permeability test method using the electric field sensor method, a coulometric oxygen permeability measurement device (OX-TRAN 2 / 22L manufactured by MOCON) has a temperature of 40 ° C, a relative humidity of 90%, an oxygen gas concentration of 5%, and a permeation area. When measured under the condition of 5 cm ² , the oxygen permeability at a measurement time of 24 hours was 406 cc / m ² / day / atm.

  Further, the mechanical strength of the obtained film was evaluated by a tensile breaking test. When a uniaxial extension test was performed using a JTT LSC-005 / 30 type tensile tester, the Young's modulus was 1.29 GPa, the tensile strength at break was 0.49 GPa, and the tensile strain at break was 0.06 mm / mm.

The proton conductivity of the obtained membrane was measured with a Toyo Technica membrane resistance measurement system (MTS740 type). Under the conditions of 10 MHz to 10 Hz and OVDC 20 mV, proton conductivity was on the order of 10 ⁻⁵ S / cm at 80 ° C. and 90% humidity, and on the order of 10 ⁻⁷ S / cm at 25 ° C. and 20% humidity.

  Moreover, the flame retardance based on the flame retardance test UL94 (vertical combustion test) was evaluated about the obtained film | membrane. Based on the 20 mm vertical combustion test (IEC60695-11-10 Method B, ASTM D3801), a strip sample of 125 ± 5 mm × 13.0 ± 0.5 mm × 24 μm was mounted vertically on the clamp, and a 10-second indirect flame with a 20 mm flame was applied. When the flame retardancy was classified by the combustion behavior twice, the clay mineral-cedar-derived low-modified lignin composite film showed flame retardancy compatible with V-0.

Example 2 <Preparation of clay mineral-low-modified lignin composite film>
A dispersion similar to that of Example 1 was prepared using a rice straw-derived low-denatured lignin ultrapure water dispersion, stretched on a PET sheet under the same conditions, and dried at room temperature. After drying, the membrane was separated from the PET sheet and heated in an electric furnace at 150 ° C. for 2 hours. By this heat treatment, a clay mineral-low-modified lignin composite film having a film thickness of 26 μm was obtained. The ratio of “Kunipia M” and low denatured lignin derived from rice straw in the composite membrane was “Kunipia M”: Low denatured lignin = 80 wt%: 20 wt%.

  The obtained film retained the form before heating, and was a film having flexibility and handling properties. The total light transmittance and haze value of the clay mineral-rice straw-derived low-modified lignin composite film were evaluated by HADEN METER (NDH5000) manufactured by Nippon Denshoku Industries Co., Ltd., and were 56% and 57%, respectively.

  The resulting film was measured for ultraviolet-visible absorption spectrum with a spectrophotometer (HITACHI U-2910), and the transmittance for each wavelength was evaluated. The transmittance at 400 nm was 5.6%, and the ultraviolet region below that ( Even at 400 nm or less, it was 10% or less. The π-conjugate derived from the aromatic network structure of lignin is considered to absorb light in the ultraviolet wavelength region. Compared with the low-denatured lignin derived from cedar, the low-denatured lignin derived from rice straw has a syringyl structure that creates a number of cross-linked structures.

  When the obtained film was subjected to thermal mass spectrometry using TG-8120 manufactured by Rigaku, the mass loss by heating up to 200 ° C was 13% by weight, which is considered to be derived from desorption of adhering water. It was.

Further, the water vapor permeability of the obtained film was measured by a cup method (moisture permeability test method for moisture-proof packaging material; JIS K 8123). The permeability at a measurement time of 24 hours was 1092 g / m ² / day. Compared to cedar-derived lignin, the water content of rice straw-derived lignin is high, so water vapor permeability is expected to be relatively high.

In addition, the membrane obtained was evaluated for oxygen permeability by the Mocon method (plastic-film and sheet-gas permeability test method-part 2: isobarometric method; JIS K 7126-2: 2006). According to the oxygen gas permeability test method using the electric field sensor method, a coulometric oxygen permeability measurement device (OX-TRAN 2 / 22L manufactured by MOCON) has a temperature of 40 ° C, a relative humidity of 90%, an oxygen gas concentration of 5%, and a permeation area. When measured under the condition of 5 cm ² , the oxygen permeability at a measurement time of 24 hours was 52.8 cc / m ² / day / atm. The water content of rice straw-derived lignin is higher than that of cedar-derived lignin, so gas permeation is inhibited and oxygen permeability is expected to be relatively low.

  Further, the mechanical strength of the obtained film was evaluated by a tensile breaking test. When a uniaxial extension test was conducted using a JTT LSC-005 / 30 type tensile tester, the Young's modulus was 0.77 GPa. In addition, a clear break point was not confirmed in the strain range of 0 to 0.5 mm / mm.

The proton conductivity of the obtained membrane was measured with a Toyo Technica membrane resistance measurement system (MTS740 type). Under the conditions of 10 MHz to 10 Hz and OVDC 20 mV, proton conductivity was on the order of 10 ⁻⁵ S / cm at 80 ° C. and 90% humidity, and on the order of 10 ⁻⁷ S / cm at 25 ° C. and 20% humidity.

Moreover, the flame retardance based on UL94 (vertical combustion test) was evaluated about the obtained film | membrane. Based on the 20 mm vertical combustion test (IEC60695-11-10 Method B, ASTM D3801), a strip sample of 125 ± 5 mm × 13.0 ± 0.5 mm × 24 μm was mounted vertically on the clamp, and a 10-second indirect flame with a 20 mm flame was applied. When the flame retardancy was classified by the combustion behavior twice, the clay mineral-rice straw-derived low-modified lignin composite film showed flame retardancy suitable for V-0.
Example 3 <Preparation of clay mineral-low-modified lignin composite film>
Under the same conditions as in Example 1, composite membranes were prepared in which the ratios of “Kunipia M” and rice straw-derived low-modified lignin were 90 wt%: 10 wt% and 70 wt%: 30 wt%, respectively. The film thickness was about 30 μm. The total light transmittance and haze value of the obtained film were 50%, 76% (90% by weight: 10% by weight) to 37%, 63% (70% by weight: 30% by weight), respectively. The transmittance at 400 nm was 4.2% (90% by weight: 10% by weight) to 2.4% (70% by weight: 30% by weight).

Example 4 <Preparation of clay mineral-low-modified lignin composite film>
Under the same conditions as in Example 1, a composite membrane in which the ratio of Li-Stevensite and cedar-derived low-modified lignin was 80% by weight: 20% by weight was prepared. The film thickness was about 20 μm. The total light transmittance and haze value of the obtained film were 65% and 12%, respectively. In addition, the mass loss upon heating up to 200 ° C. was 13% by weight, which was considered to originate from the desorption of adhering water.

  The lignin clay composite membrane of the present invention is a functional membrane composed of a plant-derived aromatic polymer and clay mineral, and has excellent ultraviolet absorbing ability, nonflammability, moisture permeability, gas permeability, and proton conductivity. Therefore, it can be used in a wide range of applications such as architectural / automotive window films, waterproof / waterproof sheets, battery separators, and the like.

Claims (7)

  It includes a low-modified lignin and a clay mineral whose yield of aromatic compound monomer obtained by alkaline nitrobenzene oxidation reaction is 15% or more, nonflammability equivalent to vertical flammability test UL94 V-0, and 90% or more at 400 nm. Lignin clay composite film having the ultraviolet absorption characteristics of   The lignin clay composite film according to claim 1, wherein the film thickness is 3 to 100 μm.   The lignin clay composite film according to claim 1 or 2, wherein a mass ratio of the low-modified lignin and the clay mineral is 5 parts by mass: 95 parts by mass to 40 parts by mass: 60 parts by mass.   A plant raw material containing cellulose, hemicellulose and lignin is wet pulverized in the presence of cellulose and hemicellulose saccharifying enzyme to obtain a pulverized product, and the pulverized product is obtained by an nitrobenzene oxidation reaction with a liquid component containing a saccharide. The solid component is separated into a solid component containing a low-modified lignin having a yield of 15% or more of the group compound monomer, and then the solid component dispersion and the clay mineral are mixed and then coated on the support and dried. To produce a lignin clay composite film containing a low-modified lignin and a clay mineral and having an incombustibility equivalent to the vertical combustion test UL94 V-0 and an ultraviolet absorption property of 90% or more at 400 nm. A method for producing a lignin clay composite film.   The method for producing a lignin clay composite film according to claim 4, wherein the film thickness is 3 to 100 μm.   The method for producing a lignin clay composite film according to claim 4 or 5, wherein the mass ratio of the low-modified lignin and the clay mineral is 5 parts by mass: 95 parts by mass to 40 parts by mass: 60 parts by mass.   The manufacturing method of the lignin clay composite film of any one of Claims 4-6 which heat-processes a lignin clay composite film at 100-200 degreeC, and makes it water resistance.