JP5115973B2 - Method for producing molded article made of natural material using cross-linking reaction of polymer tannin - Google Patents

Description

  The present invention relates to a method for producing a molded article made of a natural material from a plant fiber material, in particular, a plant residue using a crosslinking reaction of polymer tannin.

  Plant residues such as wood flour, bamboo flour, tea grounds, coffee lees, soybean pomace, and fruit juice lees were simply discarded, burned, or used as feed, and had little utility value. .

  Patent Document 1 describes a biodegradable plastic obtained by mixing and molding a vegetable fiber material and a binder made of a natural material such as persimmon.

  However, the biodegradable plastic of Patent Document 1 has a decrease in strength due to low water repellency and high water absorption, so that commercialization as a life chemical product is limited.

  Non-Patent Document 1 describes a method for making wood flour with polymer tannin using formaldehyde as a crosslinking agent.

  Boards made in this way are highly durable and can withstand boiling for 72 hours, but formaldehyde is toxic and should be avoided as much as possible.

JP 2005-23262 A H. Yano, P.J.Collins and Y. Yazaki, Jour.Materials Sci., 36, 1932-1942 (2001)

  An object of the present invention is to provide a molded article made of a natural material that is friendly to humans and the environment, using plant fiber materials, particularly plant residues.

  As a result of repeated studies in view of the above problems, the present inventors have found that the above problems can be solved by utilizing an oxidase reaction or an enzyme-like reaction, and have completed the present invention.

That is, the gist of the present invention is as follows.
(1) A plant fiber material and a polymer tannin are mixed, treated with (i) hydrogen peroxide and peroxidase, or (ii) hydrogen peroxide and a metalloporphyrin complex, and then molded by heating and pressing. A manufacturing method for molded products made of natural materials.
(2) The method according to (1) above, wherein the plant fiber material is a plant residue.
(3) The method according to (1) or (2) above, wherein the polymer tannin is condensed tannin.
(4) The method according to any one of (1) to (3), wherein the metalloporphyrin complex is an iron-protoporphyrin complex.
(5) A molded product obtained by the method according to any one of (1) to (4).

  According to the present invention, it is possible to provide a molded article made of a natural material from a plant fiber material, particularly a plant residue, using a method that is friendly to humans and the environment.

  Hereinafter, the present invention will be described in detail.

  The plant fiber material used in the present invention is not particularly limited as long as it is a material derived from plants and mainly composed of cell walls or cellulose. Further, as the plant fiber material used in the present invention, a material obtained by performing a defibrating process to remove components other than cellulose can be used. However, from the viewpoint of effective use of plant waste, a defibrating process is required. It is preferable to use the vegetable residue as it is. The plant residue is not particularly limited as long as it is derived from a plant and has a cell wall as a main component. For example, wood flour, bamboo flour, tea powder, coffee lees, soybean lees (for example, tofu lees (o )), Fruit juice squeezed rice cake, vegetable scraps, vegetable cooking scraps and the like.

  The plant fiber material is usually pulverized and used as a dry powder of about 100 mesh.

  When using plant residues as plant fiber materials, it is preferable to deaerate the plant residues in advance by high-pressure steam treatment from the point of penetration of the tannin solution over the details of the dry powder, and high cross-linking at the time of cross-linking From the viewpoint of securing the degree, it is preferable to remove the low molecular weight compound by filtration.

  The high-pressure steam treatment is preferably carried out using an apparatus such as an autoclave at a high temperature of about 100 to 140 ° C., preferably about 115 to 130 ° C. for 15 to 30 minutes (similar effects are expected even with boiling treatment for the same time). Is possible). It is desirable to degrease vegetable residues (such as coffee lees and squeezed lees from soybeans) with a high oily content. The filtration is preferably No. It is carried out with a filtration device comparable to the conditions for filtering with about 2 filter paper.

  Tannins are natural products extracted from plant trunks, skins, leaves, fruits, etc., and are environmentally friendly substances. Tannin includes pyrogallol-based hydrolyzable tannin and catechol-based condensed tannin.

  The polymer tannin used in the present invention is a polyphenol polycondensate extracted from plant trunk, skin, leaves, fruits, etc. with hot water, alcohol, etc., exhibits astringency, strongly binds to many proteins and precipitates. In general, the molecular weight is about 2,000 to about 1,000,000, preferably 10,000 or more. In the present invention, any of hydrolyzed and catechol-based condensed tannins may be used, but catechol-based condensed tannins are preferred. Examples of the high molecular tannin include high molecular tannin contained in heartwood and bark such as quebracho tannin, mimosa tannin and wattle tannin; high molecular tannin contained in immature fruits such as banana, apple and oyster; carob beans, grapes, etc. High-molecular-weight tannin contained in unripe pods and seeds.

  In general, polyphenols such as catechin and the like contained in green tea and black tea called “tannin” are low in molecular weight, have almost no skin tanning action, weakly bind to proteins, have a molecular weight of 290 catechins, and even large ones from 400 500, which is different from the polymeric tannin used in the present invention.

  The polymer tannin is usually dried and used as a powder after extraction from the raw material, but the extract from the raw material may be used as it is.

  The raw materials for high molecular tannin (for example, persimmon astringent for oyster tannin) contain organic acids, amino acids, etc. in addition to high molecular tannin. May be.

  In the present invention, the weight ratio (as dry weight) of the plant fiber material freeze-dried or hot-air dried and the polymer tannin is usually 50: 1 to 1: 1, preferably 20: 1 to 5: 1. The plant fiber material and the polymer tannin are usually mixed in an aqueous solvent such as water or a buffer solution. Usually, the dried or wet plant fiber material (vegetable residue) and the polymer tannin solution are kneaded in a weight ratio of 1: 2 to 2: 1, preferably 1: 1.

  It is preferable that the mixture of the plant fiber material and the polymer tannin solution is sufficiently stirred so that the plant residue is sufficiently covered with the polymer tannin and the cell walls are bonded and bonded with the polymer tannin. Stirring is preferably carried out with sufficient stirring for 1 to 6 hours in a kneader.

  In the present invention, the mixture of the plant fiber material and the polymer tannin is crosslinked using an oxidase reaction or an enzyme-like reaction.

  In the present specification, “oxidase reaction” refers to treatment with hydrogen peroxide and peroxidase, and “enzyme-like reaction” refers to treatment with hydrogen peroxide and a metalloporphyrin complex.

  In order to promote the reaction effectively while shortening the drying time, the enzyme reaction and the enzyme-like reaction are preferably performed in a muddy state. Therefore, it is preferable to add a polymer tannin solution in an equal amount (weight ratio) to the dry powder of plant fiber (plant residue) and knead well.

  When crosslinking is performed using an oxidase reaction, the polymer tannin concentration in the reaction solution is usually 1 to 25% by weight, preferably 2.5 to 15% by weight, more preferably 5 to 10% by weight, and the pH is Usually, 4 to 10, preferably 5 to 9, and more preferably 5.5 to 7. If necessary, the pH may be adjusted with a buffer solution, an acid such as dilute hydrochloric acid, sulfuric acid, acetic acid or citric acid, or a base such as dilute sodium hydroxide, potassium hydroxide, sodium carbonate or ammonia.

The peroxidase used in the present invention is an oxidoreductase that catalyzes the reaction of AH ₂ + H ₂ O ₂ → 2H ₂ O + A (AH ₂ is an electron donor), and is derived from animals, plants, microorganisms, or genetic engineering means. Can be used. In the present invention, peroxidase catalyzes a reaction that oxidizes the phenolic hydroxyl group of polymer tannin using hydrogen peroxide as an oxidizing agent. In general reactions involving low-molecular-weight polyphenols, phenolic hydroxyl groups are oxidized by peroxidase to form quinones, and this highly reactive quinone reacts with the surrounding benzene ring and phenolic hydroxyl groups, and it is assumed that crosslinking occurs. In high molecular weight tannins, it is speculated that the same reaction occurs mainly, but the details are under investigation. The concentration of peroxidase in the reaction solution is usually 0.001 to 100 mg, preferably 0.01 to 10 mg per 200 ml of the reaction solution (muddy suspension).

  Hydrogen peroxide is usually used as a 1 to 20% by weight aqueous solution. The concentration of hydrogen peroxide in the reaction solution is usually 15 to 120 mM, preferably 50 to 80 mM.

  The treatment temperature is usually 0 to 70 ° C., preferably 5 to 70 ° C., more preferably 10 to 40 ° C., and the treatment time is usually 30 seconds to 48 hours, preferably 30 minutes to 24 hours.

  The reaction may be either a stationary reaction or a stirring reaction. However, in order to produce a homogeneous product, it is desirable that the reaction is allowed to stand for a long time after sufficient stirring. The reaction is stopped by adding an amino acid or protein having an active amino group or cystenyl group.

  When crosslinking is performed using an enzyme-like reaction, the polymer tannin concentration in the reaction solution is usually 1 to 25% by weight, preferably 2.5 to 15% by weight, more preferably 5 to 10% by weight, and the pH is Usually around neutral. If necessary, the pH may be adjusted with a buffer solution, an acid such as dilute hydrochloric acid, sulfuric acid, acetic acid or citric acid, or a base such as dilute sodium hydroxide, potassium hydroxide, sodium carbonate or ammonia.

  The metal porphyrin complex used in the present invention is preferably a metal protoporphyrin complex, a metal deuteroporphyrin complex, a metal diacetyl deuteroporphyrin complex, a metal mesoporphyrin complex, a metal diformyl porphyrin complex, a metal tetraphenyl porphyrin complex, or a metal octaphenyl porphyrin complex. An ethyl porphyrin is mentioned. The central metal is preferably iron or cobalt, particularly iron (III).

で示されるヘミン及びヘマチンが挙げられる。金属ポルフィリン錯体の反応溶液中の濃度は、反応溶液（ドロドロの懸濁液）２００ｍｌ当たり、通常０．００１〜１００ｍｇ、好ましくは０．０１〜１０ｍｇである。 As a specific example of a preferable metal porphyrin complex,
The following formula:

The hemin and hematin shown by these are mentioned. The concentration of the metal porphyrin complex in the reaction solution is usually 0.001 to 100 mg, preferably 0.01 to 10 mg per 200 ml of the reaction solution (muddy suspension).

  Hydrogen peroxide is usually used as a 1 to 20% by weight aqueous solution. The concentration of hydrogen peroxide in the reaction solution is usually 15 to 120 mM, preferably 50 to 80 mM.

  The treatment temperature is usually 10 to 30 ° C., preferably 20 to 25 ° C., and the treatment time is usually 8 to 48 hours, preferably 12 to 24 hours.

  The reaction may be either a stationary reaction or a stirring reaction. However, in order to produce a homogeneous product, it is desirable that the reaction is allowed to stand for a long time after sufficient stirring. The reaction is stopped by adding an amino acid or protein having an active amino group or cystenyl group.

  The polymer tannins in the mixture, the polymer tannins and the cell wall lignin or structural protein are crosslinked and reinforced by the crosslinking reaction utilizing the oxidase reaction or the enzyme-analogous reaction.

  After completion of the crosslinking reaction, the reaction solution can be dried by, for example, freeze drying to obtain a crosslinked product powder.

  The crosslinked product powder obtained as described above is placed in a mold and molded by heating and pressing to produce a molded product made of the desired natural material, such as a flat board or various containers. Can do. Heating and pressurization may be performed at the same time, heating after pressurization, or pressurization after heating. The heating temperature is usually 160 to 220 ° C., preferably 180 to 200 ° C., and the pressure condition is usually 30 to 130 MPa, preferably 60 to 100 MPa.

  Various additives can be used for this invention in the range which does not impair the effect of this invention as needed.

  The molded product made of the natural material of the present invention is made of 100% natural material that is friendly to humans and the environment, and can be burned as a fuel after use. Is expensive.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, the scope of the present invention is not limited to these Examples.

  In the following examples, purified oyster tannin powder obtained from Maruzen Pharmaceutical Co., Ltd. (Onomichi, Hiroshima Prefecture) was used as oyster tannin.

(Example 1) Formation of board by cross-linking reaction using metal porphyrin complex (1) Coating / adhesion with polymer tannin 100 mesh commercial cedar wood flour (undried product (estimated moisture content 20-30%)) 100 g Distilled water was added to (volume of about 500 ml) to make 1.5 L, and autoclaved (at 121 ° C. for 20 minutes). After decantation at room temperature (3 to 5 times), filtration under reduced pressure was performed with a Buchner funnel (wet weight 203 g).
Distilled water is added to 10 g of oyster tannin powder (freeze-dried product), 110 ml of 5% tannin aqueous solution prepared in a constant volume of 200 ml is added to 203 g (whole amount) of wet cedar wood powder after vacuum filtration, and kneading machine For about 1 hour. Since the sample remained on the bottom and side of the bowl, the sample was mixed with a spatula every 5 minutes.
(2) Crosslinking reaction 400 mg of hematin powder well pulverized in a mortar was mixed with the wet wood powder of the above (1) and sufficiently stirred with a stirrer. The reaction was carried out at room temperature for 3 hours while adding 10 ml of a 5% aqueous hydrogen peroxide solution every 15 minutes (12 times, 120 ml added in total). The reaction mixture (about 400 g) was transferred to a large petri dish and incubated overnight in a 35 ° C. incubator to promote the reaction. Twenty-four hours later, the two halves were combined into one in a 1 L beaker, 70 ml of distilled water was added, and the mixture was stirred with a stirrer for 1 hour. After about 24 hours, it was taken out, 5 g of milk casein was added, and the mixture was sufficiently stirred for 1 hour in a kneader. The sample increased in viscosity and changed into a bowl shape. Furthermore, it was placed in a 35 ° C. incubator overnight. And it preserve | saved overnight at -30 degreeC freezer and frozen. Thereafter, freeze-drying was performed to prepare a dry powder (108 g).
(3) Heating / Compression The temperature of the press machine was set to 180 ° C. both in the upper and lower directions. 15 g of the sample (2) was placed in a cylindrical die having a diameter of 7 cm. At this time, samples were taken little by little, and packed so as to overlap thin layers. After confirming that the temperature of the press was approaching 180 ° C., the cylindrical die was placed in the center of the press plate, and pressing was started. The pressure was increased until the pressure reached 30 MPa, and the mixture was left for 10 minutes after reaching 30 MPa. (Since this time, the pressure gradually decreased, pressure was applied as needed to maintain 30 MPa.) After 10 minutes, the sample was taken out. Further, the pressure was increased to 85 MPa and maintained for 10 minutes.
Thereafter, a sample was taken out to prepare a disk-shaped board (thickness 3 mm, diameter 7 cm).

(Example 2) Formation of board by cross-linking reaction using peroxidase enzyme (1) 100 g of commercially available cedar wood flour (undried product (estimated moisture content 20-30%)) of 100 mesh was subjected to high-temperature steam treatment and after cooling Decantation (gradient method) was performed 3 to 5 times to remove as much water-soluble substances as possible. Then, no. Excess water was removed by filtration under reduced pressure using a Buchner funnel set with No. 2 filter paper. (187g)
(2) 100 ml of a 5% cachytannin aqueous solution was added at a weight ratio of 2 to 1, and the mixture was sufficiently stirred and kneaded at room temperature for 2 hours.
(3) 1 ml of an aqueous solution of 1 mg / ml of commercially available horseradish peroxidase was added, and 10 ml was added dropwise while adding 5% aqueous hydrogen peroxide while stirring and kneading well, and stirring was continued.
(4) This was done 6 times at 10-minute intervals for 1 hour, and continued for a total of 2 hours.
(5) After the addition, the entire suspension in a muddy state was reacted at 35 ° C. overnight in an incubator.
(6) After the reaction, a solution of milk casein in a 5 g / 50 ml solution was added and sufficiently stirred and kneaded for 1 hour.
(7) Placed in Tupperware and frozen overnight.
(8) It dried with the freeze dryer. (Dry powder: 106g)
(9) 15 g of the dry powder was put into a cylindrical stainless steel mold having a diameter of 7 cm, and compressed by a hot press machine under conditions of 180 ° C., 90 MPa, 30 minutes. A disk board with a thickness of about 3 mm was made.

(Example 3) Evaluation of created board (1) Appearance and feel From the color and feel of the molded product, it was determined how much the original wood flour changed. Insufficient molding was a powdery texture. The finished product had a touch and texture like pottery. Also, the sound when hit was close to pottery.
(2) Strength test by bending test and bending strength test A tensile test was performed using a small tabletop testing machine. Many samples were molded using a hot press die (JIS-K7171 type) and tested. In addition, a disk-shaped board was cut with a saw to create a rectangular section, and a strength test was also conducted. In the strength test by the tensile test and the bending strength test, relatively weak hot press conditions (for example, 30 MPa, 10 minutes, 180 or 170 ° C.) were selected in order to clarify the influence of the material.
(3) Water-repellent test A disc-shaped molded article (diameter 7 cm) prepared from 10 g or 15 g of lyophilized powder was immersed in hot water at 35 ° C. for 20 hours, and the change in weight and thickness was examined. When making a disk-shaped molded product, relatively strong hot pressing conditions (usually 180 ° C., 60 MPa at 10 to 30 minutes) were selected.
(4) Results It was revealed that the addition of 5% or 10% milk casein to the addition of 5% and 10% kakitannin to the wood flour increases the strength and water repellency. Using this material, hot press (180 ° C, 90MPa, 30 minutes) under stronger conditions creates a board that absorbs almost no water in the immersion process at 35 ° C for 24 hours without losing the woody texture. I was able to confirm that it was possible.

  FIG. 2 shows the influence of the ratio of oyster tannin and milk casein (MC) on the strength in the tensile strength test of the key board molded product (tannin concentration: 5%, milk casein concentration: 0 to 20%, cross-linking reaction: to Min and hydrogen peroxide, hot press conditions: 180 ° C., 30 MPa 10 minutes to 60 MPa 10 minutes, sample amount: 7 g).

  FIG. 3 shows the influence of the ratio of kakitannin (KT) and milk casein (MC) on the bending strength in the bending strength test of the key board molded product (tannin concentration: 5%, milk casein concentration: 0-20%, Crosslinking reaction: hemin and hydrogen peroxide, hot press conditions: 180 ° C., 30 MPa 10 min to 60 MPa 10 min, sample amount: 7 g).

  2 and 3, “STROKE” indicates the elongation (mm) of the sample during pressurization during the strength test. In FIG. 3, “Wfoundly” indicates a case where only wood flour is used.

  FIG. 4 shows the effect of the ratio of oyster tannin (KT) and milk casein (MC) on water repellency in a water repellency test of a disk-shaped board molded product (tannin concentration: 5%, milk casein concentration: 0-20%, Crosslinking reaction: hemin and hydrogen peroxide, hot press conditions: 180 ° C., 30 MPa 10 minutes to 60 MPa 10 minutes, sample amount: 10 g). In FIG. 4, “WFOnly” indicates a case where only wood flour is used.

  The bowl-shaped molded product shown in FIG. 5 was prepared based on this result (tannin concentration: 5%, milk casein concentration: 5%, crosslinking reaction: hemin and hydrogen peroxide, hot press conditions: 180 ° C., 60 MPa. , 30 minutes). Under similar conditions, it was also possible to produce molded products not only from wood flour, but also from bamboo flour, coffee residue, tea husk, soybean meal, and orange juice juice.

  The molded product of the present invention can be used, for example, as a disposable beverage or food container, tableware, lunch box, or the like, a home appliance, a car, a mobile phone, or a personal computer board.

It is a photograph which shows the representative example of the disk-shaped board molding for water-repellent tests, and the key-type board molding for a tensile strength test and a bending strength test. It is a figure which shows the influence which the ratio of oyster tannin and milk casein (MC) gives to intensity | strength in the tensile strength test of a key-type board molded product. It is a figure which shows the influence which the ratio of kakitannin (KT) and milk casein (MC) gives to bending strength in the bending strength test of a key-type board molded product. It is a figure which shows the influence which the ratio of oyster tannin (KT) and milk casein (MC) has on water repellency in the water repellency test of a disk-shaped board molded product. It is a photograph showing a 100% natural product bowl-shaped molded product based on wood flour.

Claims (5)

Mixing the plant fiber material and polymeric tannins, after treatment with hydrogen peroxide and metal porphyrin complexes, heating and moldings method of manufacturing consisting of natural materials, characterized in that pressurized molding.   The method of claim 1, wherein the plant fiber material is a vegetable residue.   The method according to claim 1 or 2, wherein the polymer tannin is condensed tannin.   The method according to any one of claims 1 to 3, wherein the metalloporphyrin complex is an iron-protoporphyrin complex.   The molded article obtained by the method of any one of Claims 1-4.

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