JP2008155531A - Method for manufacturing plant fragment containing molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new technical means which enables the manufacturing of an extrusion molded article of a plant origin by using no plastic when using a plant fragment containing hemicellulose as a raw material and obtaining a molded article containing a plant fragment by using no adhesive by using as an adhesion composition a composition contained in a plant fragment or the modified material thereof. <P>SOLUTION: The plant fragment containing hemicellulose is adjusted so that the water content may become ≥20% and ≤200%, and the extrusion molding is carried out with an extrusion molding machine, thereby manufacturing the plant fragment containing molded article. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention uses a plant strip containing hemicellulose as a raw material, a component contained in the plant strip or a modified substance thereof as an adhesive component, and a method for producing a plant strip-containing molded product obtained without using an adhesive It is about.

  2. Description of the Related Art Conventionally, in the plastic field, extrusion molding by combining a resin such as vinyl chloride and polypropylene with wood flour has been widely performed. Since wood powder alone is not plastic and has no adhesiveness, efforts have been made to thermoplasticize wood by esterification or etherification, but since sufficient fluidity cannot be secured, resin is added to wood powder. The resin is melted and plasticized, and the resin is solidified to form a molded product.

  A molded product in which a resin and a wood powder are combined has a texture similar to that of a wood member, and a cheap wood powder is used as an extender.

  However, when the ratio of the resin is high, there is a problem that the ratio of petroleum-derived materials increases in addition to high cost and a texture close to that of a wooden member. In recent years, as interest in environmental issues such as global warming has increased, attention has been focused on low-emission and carbon-neutral plant-derived materials from petroleum-derived materials. It is desired to achieve performance such as a required degree of fixation as a product.

  Moreover, when vinyl chloride etc. are used as resin, there exists a concern that the plasticizer etc. which are contained in the resin are environmental hormones. When a resin containing formaldehyde is used as the resin, harmful components such as formaldehyde volatilize, which may adversely affect the health of residents. Furthermore, in the case of incineration, there is also a problem that harmful gases are generated due to the combustion of the resin.

  From these viewpoints, development of a plant-derived extruded product that can be molded without using a resin is strongly desired.

  Therefore, conventionally, without using resin, plant strips such as particles and fine fibers are heat-press molded with a press, and plant strips are bonded to each other with adhesive components contained in plant strips. It is proposed to be a product. For example, a method for producing a binderless board by heat-pressing a plant material such as bagasse, corn stalk, sunflower stalk, flax stalk, etc. as a raw material (Patent Document 1) or a mallow bast fiber plant as a lignocellulose material Various proposals have been made such as a method of manufacturing a binderless board by heat-press molding using a material (Patent Document 2).

However, all of the conventionally proposed methods are limited to those by heat and pressure molding of plant strips, and can be continuously molded, improving the productivity and the value of product diversification. For extrusion molding, which is expected to be achieved, it has been difficult to obtain a molded product without using a resin.
Japanese Unexamined Patent Publication No. 60-30309 Japanese Patent No. 3034956

  In view of the background as described above, an object of the present invention is to provide a new technical means that makes it possible to produce a plant-derived extruded product without using a resin.

  The present invention provides a manufacturing method having the following characteristics.

  First: A plant strip containing hemicellulose is adjusted so that its moisture content is 20% or more and 200% or less, and extrusion molding is performed with an extruder to produce a plant strip-containing molded product.

  Second: In the above method, plant fragments containing hemicellulose are obtained by pulverizing a kenaf stalk.

  Third: The kneading and molding temperature in the extruder is 150 ° C. or higher and 240 ° C. or lower.

  According to the first invention method as described above, by adjusting the water content of the plant strip containing hemicellulose to 20% or more and 200% or less by adding water to the plant strip, etc., the plant strip Can be kneaded in the extruder, and the moisture in the plant fragments becomes water vapor in the extruder to hydrolyze the hexcellulose in the plant fragments and recondensate to modify the adhesive component. Then, the plant strips are bonded to each other by bonding with other components such as cellulose, lignin, or their pyrolysates, thereby enabling the molding of an extruded product.

  Thereby, without using a resin, only a plant-derived material can be used to achieve extrusion of a plant-strip-containing molded product that is highly productive and valuable as product diversification.

  In addition, according to the second invention method using a kenaf stalk pulverized plant fine piece, the kenaf stalk has a high content of hemicellulose component, so more reliably performance such as adhesion strength. An excellent plant strip-containing molded product can be produced.

  Furthermore, according to the third invention method in which the kneading and molding temperature in the extruder is 150 ° C. or more and 240 ° C. or less, by promoting the thermal decomposition of cellulose, lignin and the like, the physical properties of the molded product are improved, Denaturation and discoloration can be suppressed more effectively.

  In the present invention, the plant material used as the raw material of the plant strip is not particularly limited, but a plant of annual or biennial vegetation, or grains, vegetable oil, plant sugar, plant fiber, etc. are collected. Later agricultural waste can also be used. Specifically, for example, hemp plants such as kenaf, jute and flax, and stems such as rice, hagas, wheat, corn and sunflower can be used. By using these, resources can be effectively used. In particular, the core of kenaf, jute, flax and other hemp plants, especially kenaf, excluding the bast, which is the epidermis of the stem, is mainly composed of cellulose, hemicellulose, and lignin, as is the case with softwood and hardwood. However, compared with wood, the content of the hemicellulose component is high and the adhesive component is rich, which is suitable as the material of the present invention.

  In the present invention, for example, water content is adjusted by adding water to a strip obtained by cutting or pulverizing a stem portion of these plant materials, plasticizing, and kneading in an extruder is possible. In the extruder, the moisture in the plant pieces becomes water vapor when the temperature is 100 ° C. or higher, and the hemicellulose in the plant pieces is hydrolyzed in a water vapor atmosphere and then recondensed to be modified into an adhesive component. The adhesive component is bonded in the extruder. By combining with other components or with other components such as cellulose and lignin, the plant pieces are adhered to each other so that an extruded product can be extruded.

  In the present invention, the moisture content of the plant strip is preferably 20% or more and 200% or less. Here, the moisture content is defined as calculated by the following formula.

(Weight before drying-Weight after drying) / Weight after drying The moisture content defined as described above is difficult to extrude because the fluidity in the extruder is low if it is less than 20%. Bonding effect is small. If it exceeds 200%, moisture will be excessive at the time of molding, and the temperature of the extruder will not rise, and moisture will remain in the molded product even after extrusion, forming a cavity inside, or bursting the molded product. In order to prevent this, it is necessary to evaporate water by slowing the extrusion speed, and the extrusion time is prolonged and the molding efficiency is lowered, and the residence time in the extruder is lengthened. Denaturation, discoloration, etc. will be caused.

  Furthermore, when the moisture content of the plant pieces is 30% or more and 100% or less, the fluidity in the extruder is high, and the hemicellulose in the plant pieces is hydrolyzed in a steam atmosphere in the extruder and then recondensed to form an adhesive component. It is more preferable because it has a great effect of promoting bonding, and moisture remains in the molded product after extrusion, and there are no problems such as formation of cavities, bursting of the molded product, or discoloration.

  Adjustment of the moisture content of 20% or more and 200% or less can be achieved by adding water to plant strips, for example, by adding water by spraying, dipping, etc., or by nature, or by drying by heating, or a combination thereof It can be carried out.

  The shape of the strip is not particularly limited as long as the moisture content is adjusted to be 20% or more and 200% or less and has a shape having plasticity. These plant materials, for example, by pulverization, can be processed into granular strips having a diameter of several hundred μm to several cm. Although not particularly limited, in the extrusion molding of the present invention, it is preferable that the average particle size of the plant strips be in the range of about 0.4 to 8 mm.

  In addition, although the extrusion molded article of this invention adheres a plant strip with the adhesive component contained in a plant strip, you may make it adhere | attach using some synthetic resins etc. together.

  In the present invention, the kneading / molding temperature in the plant strip extruding machine is preferably 150 ° C. or higher and 240 ° C. or lower. The temperature at which the hemicellulose in the plant strip is hydrolyzed in a steam atmosphere and then recondensed to denature into a strong adhesive component is preferably 150 ° C. or higher. If it exceeds 240 ° C., the thermal decomposition of the components in the plant such as cellulose and lignin becomes intense, which causes deterioration of physical properties, modification, discoloration, etc. of the molded product. From the aspect of molding efficiency, a range of 160 ° C. or higher and 210 ° C. or lower where the rate at which the hemicellulose in the plant strip is hydrolyzed in a steam atmosphere and then re-condensed and modified into an adhesive component is more preferable.

  Examples of the extrusion molding machine used for this molding include a uniaxial and biaxial extruder generally used conventionally, and a kneader ruder that performs kneading in a patch type, but is not particularly limited.

  The plant strip-containing molded article produced in the present invention may have various dimensions (thickness, width, length) and shapes (for example, board, sheet, columnar shape, linear shape, etc.). The use may be various for construction / construction, industrial use, agricultural use, medical use, and so on.

  Then, it demonstrates still more concretely by an Example next. Of course, the present invention is not limited to the following examples.

(Example 1)
After removing the bast fibers that form the outer skin of the kenaf stalk core, the kenaf stalk core is used as a plant material, pulverized with a pulverizer, and sieved with a 1 mm mesh. Obtained. The average particle size of the crushed powder was 0.7 mm. Water was added to the pulverized powder by spraying to adjust the water content to 30%.

  Next, the kneading part, the extruding part and the die part of the extrusion kneader (Kasamatsu Kneader Kruder KR-35) are heated to 150 ° C., and this crushed powder is put into a 500 g kneading part and kneaded for 2 minutes. Rotate the screw to extrude the kneaded material from the die part (opening height 0.5 cm, width 4 cm) at a speed of 0.4 cm / min, take it up by the conveyor, cut the length direction, and length 10 cm A molded article having a width of 4 cm and a height of 0.5 cm was formed.

(Example 2)
A molded product was molded in the same manner as in Example 1 except that the extruded portion and the die portion were heated to 200 ° C.

(Example 3)
A molded product was molded in the same manner as in Example 2 except that the moisture content of the kenaf stalk core crushed powder was adjusted to 100%.

(Comparative Example 1)
The water content of the same kenaf stalk core crushed powder as in Example 1 was adjusted to 10%.

  Next, the kneading part, the extruding part and the die part of the extrusion kneader (Kasamatsu Kneader Kruder KR-35) are heated to 150 ° C., and this crushed powder is put into a 500 g kneading part and kneaded for 2 minutes. The screw was rotated to try to push the kneaded material from the die part (opening height 0.5 cm, width 4 cm) at a speed of 0.2 cm / min. I couldn't do it.

  The extruding part and the die part were heated to 200 ° C. to try to extrude, but similarly, the crushed powder was not caught in the screw part, and the extruding could not be performed.

(Comparative Example 2)
As in Comparative Example 1, when the moisture content of the plant strip was low, the fluidity was low and extrusion molding could not be performed. Therefore, a molded product obtained by extrusion molding by combining polyethylene and wood powder was prepared as Comparative Example 2.

  A baitsuga wood flour having an average particle size of 0.7 mm was used as a plant material, and this wood flour was adjusted to have a moisture content of 5%.

  Next, the kneading part, the extruding part and the die part of the extrusion kneader (Kasamatsu Kneader Kruder KR-35) are heated to 150 ° C., and 425 g of this wood powder and polyethylene pellets (trade name: NOPATEC HJ-490, manufacturer) : Nippon Polyethylene Co., Ltd.) 75 g was added to the kneading part and kneaded for 4 minutes, and then the screw of the extrusion part was rotated to move the kneading part from the die part (opening height 0.5 cm, width 4 cm) to 0.4 cm / min. The product was extruded at a speed of 1, and taken up by a conveyor, and then the length direction was cut to form a molded product having a length of 10 cm, a width of 4 cm, and a height of 0.5 cm.

  The molded products obtained in Examples 1 to 3 and Comparative Example 2 above were measured for specific gravity and bending strength based on JIS A 5908. The results are shown in Table 1.

実施例１〜３の通り、ケナフ茎芯破砕粉の含水率を２０％以上２００％以下に調整し、混練押出温度を１５０℃以上２４０℃以下とすることで、樹脂を添加することなしに、押出成形品が成形できた。比較例１の通り、植物細片の含水率が低い場合は、流動性が低く押出成形を行うことが出来なかった。

As in Examples 1 to 3, the water content of the kenaf stalk core crushed powder is adjusted to 20% or more and 200% or less, and the kneading extrusion temperature is set to 150 ° C. or more and 240 ° C. or less without adding a resin. An extruded product could be formed. As in Comparative Example 1, when the moisture content of the plant strip was low, the fluidity was low and extrusion molding could not be performed.

  Further, the physical properties were higher than those of Comparative Example 2 prepared by adding polyethylene to wood flour. The hemicellulose in the plant strip is hydrolyzed in a water vapor atmosphere and then recondensed to be modified into an adhesive component, so that it is considered that sufficient strength has been developed.

  When Examples 1 to 3 are compared, there is a water content and kneading extrusion temperature at which hemicellulose in plant strips is efficiently hydrolyzed in a steam atmosphere and then recondensed to modify the adhesive component, and the water content is 50 %, The physical properties of Example 3 in which the kneading extrusion temperature was 200 ° C. were the highest.

Claims (3)

A method for producing a plant strip-containing molded article, comprising adjusting plant moisture pieces containing hemicellulose so that the moisture content thereof is 20% or more and 200% or less and extruding with an extruder. The method for producing a plant fine particle-containing molded product according to claim 1, wherein the plant fine particle containing hemicellulose is obtained by pulverizing a kenaf stalk. The method for producing a plant strip-containing molded product according to claim 1 or 2, wherein the kneading and molding temperature in the extruder is 150 ° C or higher and 240 ° C or lower.