JP5493499B2 - Method for producing thermoplastic resin composition - Google Patents

Description

  The present invention relates to a method for producing a thermoplastic resin composition. More specifically, the present invention can contain a large amount of plant fiber in a thermoplastic resin, and prevents thermal degradation of the plant fiber due to heat storage based on heat generated during kneading and mixing, and is produced by injection molding or the like. The present invention relates to a method for producing a thermoplastic resin composition in which a decrease in physical properties of a plastic resin molded product is suppressed.

  In recent years, from the viewpoint of the global environment, composite materials in which a thermoplastic resin and a plant material are mixed have been studied for various uses. For example, a method for producing a polyolefin resin composition by melting and kneading a mixed material containing a polyolefin resin and a predetermined length of wood flour, cooling and pulverizing a molten resin kneaded product is known. (For example, refer to Patent Document 1). Patent Document 1 describes that a molded article having a woody texture such as a pseudo tree can be produced by indentation molding using the resin composition produced by this method. Furthermore, plant-based fillers such as timber, cutting waste such as pulp, and pulverized plant fibers such as kenaf and thermoplastic resin are melt-kneaded, extruded, cooled, pelletized, and composite pellets A method of manufacturing is known (for example, see Patent Document 2).

JP 2004-269709 A Japanese Patent Laid-Open No. 2002-210736

  Patent Document 1 describes that a molded body such as a pseudo tree is manufactured by indentation molding using a resin composition containing up to 200 parts by mass of wood flour with respect to 100 parts by mass of polyolefin resin. However, the resin composition is manufactured by extrusion molding, and there is no particular mention regarding prevention of thermal degradation of wood flour and fluidity of the resin composition. Furthermore, Patent Document 2 describes that a composite material pellet containing a large amount of plant-based filler is produced, but the apparatus used has a complicated structure and is complicated to operate.

  The present invention has been made in view of the above-described conventional situation, and a thermoplastic resin can contain a large amount of plant fiber, and heat deterioration of the plant fiber due to heat storage based on heat generation during kneading and mixing is achieved. It is an object of the present invention to provide a method for producing a thermoplastic resin composition that is prevented and prevents a decrease in physical properties of a thermoplastic resin molded article produced by injection molding or the like.

The present invention is as follows.
1. A method for producing a thermoplastic resin composition comprising a thermoplastic resin and plant fibers, wherein the total amount of the thermoplastic resin and the plant fibers is 100% by mass, and the plant fibers are 50 to 95% by mass. A mixing step of kneading and mixing the thermoplastic resin and the vegetable fiber to obtain a resin fiber mixture, and a rolling step of rolling the resin fiber mixture to obtain a flat rolled product ,
The rolling device used in the rolling step includes a drawing roll for drawing the resin fiber mixture, and a rolling roll for rolling the resin fiber mixture fed from the drawing roll into a flat plate shape,
A process for producing a thermoplastic resin composition, wherein the attracting roll has protrusions on its peripheral surface .
2. The rolling roll is disposed below the attracting roll,
The resin fiber mixture delivered from the attracting roll is supplied to the rolling roll while falling downward . The manufacturing method of the thermoplastic resin composition as described in any one of.
3. The mixing device used for the kneading and mixing includes a mixing chamber in which the mixing is performed and a mixing blade disposed in the mixing chamber, and the heat that is heated and melted by rotation of the mixing blade in the mixing chamber. 1. The plastic resin and the plant fiber are kneaded and mixed. Or 2. The manufacturing method of the thermoplastic resin composition as described in any one of.
4). The 1 wherein rolling roll having a cooling function. The manufacturing method of the thermoplastic resin composition as described in any one of.
5. The said 1. provided with the grinding | pulverization process which grind | pulverizes the resin fiber mixture obtained in the said mixing process to make a grinding | pulverization mixture. To 4. The manufacturing method of the thermoplastic resin composition of any one of these.
6). 4. A pelletizing step of pressing and solidifying the pulverized mixture to form a pellet. The manufacturing method of the thermoplastic resin composition as described in any one of.
7). The plant fiber is a kenaf fiber. To 6. The manufacturing method of the thermoplastic resin composition of any one of these.
8). The thermoplastic resin is a polypropylene resin or an acid-modified polypropylene resin. To 7. The manufacturing method of the thermoplastic resin composition of any one of these.
9. The acid-modified polypropylene resin is 1 to 30% by mass when the total of the polypropylene resin and the acid-modified polypropylene resin is 100% by mass. The manufacturing method of the thermoplastic resin composition as described in any one of.

According to the method for producing a thermoplastic resin composition of the present invention, a resin fiber mixture obtained by mixing a thermoplastic resin and a vegetable fiber is rolled into a flat plate shape, and heat generated during mixing is dissipated from the resin fiber mixture. Is not stored. Therefore, equipment such as a water spray device and a drying device or a cooling booth and a process using them are not required. Therefore, the apparatus is complicated and the operation is not complicated, and the resin fiber mixture is sufficiently cooled to prevent the thermal deterioration of the plant fiber, the deterioration of physical properties is suppressed, and a thermoplastic resin molding that is preferable from the viewpoint of practicality. A body (hereinafter abbreviated as “molded body”) can be produced. Further, it can contain a large amount of 50 to 95% by mass of vegetable fiber, and can be made into a thermoplastic resin composition having sufficient fluidity when molded by a method such as injection molding. A molded body having a flexural modulus or the like can be manufactured.
Further, since the rolling device used in the rolling process includes a drawing roll for drawing the resin fiber mixture and a rolling roll for rolling the resin fiber mixture fed from the drawing roll into a flat plate shape, the rolling device is discharged from the mixing device. The resin fiber mixture is fed to the rolling roll without stagnation, and the resin fiber mixture can be efficiently converted into a flat rolled product.
Further, the mixing device used for kneading and mixing includes a mixing chamber in which mixing is performed and a mixing blade disposed in the mixing chamber, and a thermoplastic resin heated and melted by rotation of the mixing blade in the mixing chamber; When plant fibers are kneaded and mixed, they can be efficiently mixed in a short time without the need for external heating, and the cost can be reduced.
In addition, when the rolling roll has a cooling function, it is possible to more reliably prevent the heat storage of the resin fiber mixture and more efficiently prevent the thermal degradation of the plant fiber, compared to the case of only heat dissipation by cooling. Can do.
Furthermore, when a pulverization step is performed by pulverizing the resin fiber mixture obtained in the mixing step, the pulverized mixture can be used as it is or as a pellet as a raw material for injection molding, etc. It is easier to handle than a lump-shaped resin fiber mixture, and a molded product can be easily produced.
In addition, when a pelletizing step is performed in which the pulverized mixture is pressed and pelletized, it can be pelletized without heating, so that the thermal degradation of the thermoplastic resin is suppressed, and the pellet is easy to handle and injection molding. It can be supplied more easily and more uniformly to a machine or the like, and the mechanical properties of the molded body can be further improved.
Furthermore, when the plant fiber is a kenaf fiber, it is an annual grass with a very high growth rate, and by using kenaf having excellent carbon dioxide absorption, the amount of carbon dioxide in the atmosphere can be reduced, and plant resources can be obtained. Can contribute to the effective use of
When the thermoplastic resin is a polypropylene resin or an acid-modified polypropylene resin, a thermoplastic resin composition having higher fluidity can be obtained, and a molded article having excellent mechanical properties can be obtained. be able to.
Furthermore, when the total of the polypropylene resin and the acid-modified polypropylene resin is 100% by mass, when the acid-modified polypropylene resin is 1 to 30% by mass, the effect of using the acid-modified resin together is A thermoplastic resin composition that is sufficiently produced and has particularly high fluidity can be obtained, and a molded article having excellent mechanical properties can be obtained.

It is a part of system used for manufacture of a thermoplastic resin composition, Comprising: It is typical explanatory drawing when a mixing device, a rolling device, a grinding device, and a pelletizing device are arranged in parallel. It is typical sectional drawing of an example of a mixing apparatus. It is a typical side view of an example of the mixing blade | wing arrange | positioned at the mixing apparatus. It is a typical perspective view of the principal part of an example of a roller disc die type pelletizer.

Hereinafter, the present invention will be described in detail with reference to the drawings.
[1] Method for producing thermoplastic resin composition The thermoplastic resin composition contains a thermoplastic resin and a vegetable fiber, and the total amount of the thermoplastic resin and the vegetable fiber is 100% by mass. It is -95 mass%, and is equipped with the mixing process which knead | mixes and mixes a thermoplastic resin and a vegetable fiber, and makes it a resin fiber mixture, and the rolling process which rolls a resin fiber mixture and makes it a flat rolled product It can be manufactured by a method.
Furthermore, in this manufacturing method, the rolling apparatus used in the rolling step includes a drawing roll for drawing the resin fiber mixture and a rolling roll for rolling the resin fiber mixture fed from the drawing roll into a flat plate shape. The roll has a protrusion standing on the peripheral surface.

[1] Material (1) Thermoplastic Resin The “thermoplastic resin” is a resin mixed with plant fibers in the mixing step. This thermoplastic resin is not particularly limited, and various thermoplastic resins can be used. Examples of the thermoplastic resin include polyolefin, polyester resin, polystyrene, acrylic resin, polyamide, polycarbonate, polyacetal, and ABS resin. Further, as the thermoplastic resin, polylactic acid, polycaprolactone, polybutylene succinate, and the like can be used. Among these, polyolefins such as polyethylene, polypropylene, and ethylene-propylene copolymer are preferable, and polypropylene, ethylene-propylene copolymer, and particularly ethylene-propylene block copolymer are more preferable. Two or more thermoplastic resins may be used in combination, but only one type is often used.

  In particular, when a polyolefin is used as the thermoplastic resin, it is preferable to use an acid-modified polyolefin in combination. By using the acid-modified polyolefin, it is possible to further improve the mechanical properties of a molded article molded using the thermoplastic resin composition. As the base resin of the acid-modified polyolefin, the above-mentioned various polyolefins can be used. Furthermore, the non-modified polyolefin contained in the thermoplastic resin composition and the base resin used for acid modification are preferably the same type of resin. Further, when the resins are the same type, it is more preferable that the difference in average molecular weight, density, etc. of each resin is small, and when it is a copolymer, the difference in the proportion of each monomer unit is more small. preferable.

  The method for introducing an acid group into the acid-modified polyolefin is not particularly limited, but it can be introduced by so-called graft polymerization, which is usually carried out by reacting a polyolefin-containing compound with an acid group. The compound having an acid group is not particularly limited, and examples thereof include maleic anhydride, itaconic anhydride, succinic anhydride, glutaric anhydride, adipic anhydride, maleic acid, itaconic acid, fumaric acid, acrylic acid and methacrylic acid. These may be used alone or in combination of two or more. Of these, acid anhydrides are often used, and maleic anhydride and itaconic anhydride are often used.

The amount of acid groups introduced in the acid-modified polyolefin is not particularly limited, but is preferably an amount introduced so that the acid value is 5 or more. If the introduction amount is such that the acid value of the acid-modified polyolefin is 5 or more, the mechanical properties of the molded article can be sufficiently improved without adding a large amount of the acid-modified polyolefin. The acid value is more preferably 10 to 80, particularly 15 to 70, and further preferably 20 to 60.
The acid value can be measured according to JIS K0070.

Furthermore, the average molecular weight of the acid-modified polyolefin is not particularly limited, but the weight average molecular weight is preferably 10,000 to 200,000. That is, it is preferably a relatively low molecular weight acid-modified polyolefin. By using such an acid-modified polyolefin, the fluidity of the thermoplastic resin composition can be sufficiently improved, and a molded article having excellent mechanical properties can be obtained. The weight average molecular weight is 15,000 to 150,000, particularly 25,000 to 120,000, and more preferably 35,000 to 100,000.
The weight average molecular weight can be measured by gel permeation chromatography.

  Moreover, when using together acid-modified polyolefin, when the whole thermoplastic resin is 100 mass%, it is preferable that acid-modified polyolefin is 1-30 mass%, 1-25 mass%, especially 1-20 mass%. Furthermore, it is more preferable that it is 1.5-10 mass%. If the blending amount of the acid-modified polyolefin is 1 to 30% by mass, the fluidity of the thermoplastic resin composition at the time of molding such as injection molding can be dramatically improved and the mechanical properties of the molded body are improved. Can be made. Furthermore, as the thermoplastic resin, it is more preferable to use a polypropylene resin, for example, polypropylene and / or an ethylene-propylene copolymer, particularly an ethylene-propylene block copolymer, and a resin obtained by acid-modifying these in combination. Thereby, the fluidity of the thermoplastic resin composition at the time of molding such as injection molding and the mechanical properties of the molded body can be sufficiently improved.

(2) Plant fiber The “plant fiber” is a fiber derived from a plant. This plant fiber includes kenaf, jute hemp, manila hemp, sisal hemp, husk, cocoon, cocoon, banana, pineapple, coconut, corn, sugar cane, bagasse, palm, papyrus, cocoon, esparto, sabugrass, wheat, rice, bamboo, Examples thereof include fibers of various plants such as conifers (cedars, firewood, etc.), hardwoods, and cotton. This plant fiber may be used alone or in combination of two or more. Among these, Kenaf's fiber is an annual plant that grows very fast, has excellent carbon dioxide absorption, and can contribute to reducing the amount of carbon dioxide in the atmosphere and effectively using forest resources. Is preferred. Moreover, the site | part used among plants is not specifically limited, Any site | parts which comprise plants, such as a non-wood part, a wood part, a leaf part, a stem part, and a root part, may be sufficient. Furthermore, only a specific part may be used and two or more different parts may be used in combination.

  Kenaf is a fast-growing annual plant with a woody stem and is a plant classified as a mallow. Examples of the kenaf include hibiscus cannabinus and hibiscus sabdariffa in scientific names, as well as red hemp, cuba kenaf, western hemp, taykenaf, mesta, bimli, ambari and bombay, etc. in common names. When using the fiber which kenaf has as a plant fiber, the outer-layer part called a bast which has a tough fiber can be used.

  The fiber length and fiber diameter of the plant fiber are not particularly limited, but the ratio (L / t) of the fiber length (L) to the fiber diameter (t) is preferably 5 to 20000. Moreover, the fiber length of a vegetable fiber is 10-300 mm normally, and a fiber diameter is 10-150 micrometers normally. This fiber length is a value measured on a measuring scale by stretching one plant fiber straight without stretching in the same manner as in the direct method in JIS L1015. On the other hand, a fiber diameter is the value which measured the fiber diameter in the center part of the length direction of a fiber using the optical microscope about the vegetable fiber which measured fiber length.

Further, the average fiber length and the average fiber diameter of the plant fiber are not particularly limited, but the average fiber length is preferably 100 mm or less (usually 10 mm or more). By using a plant fiber having an average fiber length of 100 mm or less, it can be easily mixed with a thermoplastic resin. This average fiber length was measured for a total of 200 fibers by taking out single fibers at random by a direct method in accordance with JIS L1015, stretching them straight without stretching, and measuring the fiber length on a measuring scale. Average value. The average fiber diameter is preferably 100 μm or less (usually 15 μm or more). This average fiber diameter is an average value measured for a total of 200 fibers by taking out single fibers at random and measuring the fiber diameter at the center in the length direction of the fibers using an optical microscope.
In addition, the plant fiber used as this raw material fiber is usually cut and used.

  Further, the plant fiber may be mixed with the thermoplastic resin without any processing, or may be cut or pulverized and mixed with the thermoplastic resin as a predetermined length of plant fiber. Further, the plant fiber is made into a fiber pellet having a predetermined shape and size by a pelletizing device (for example, see FIG. 4 describing the main part of the device used for pelletizing the thermoplastic resin composition). You may mix with a plastic resin.

  The thermoplastic resin composition can contain other components excluding the thermoplastic resin and plant fibers. Other components are not particularly limited, and examples thereof include various additives such as antioxidants, ultraviolet absorbers, antistatic agents, flame retardants, antibacterial agents, and coloring agents. Each of these additives may be used alone or in combination of two or more. Although the process of mix | blending these other components is not specifically limited, Usually, it mix | blends and contains in a mixing process.

[2] Process The manufacturing method of the thermoplastic resin composition of the present invention includes a mixing process in which the thermoplastic resin and plant fiber are kneaded and mixed by the mixing apparatus 1 (see FIGS. 2 and 3 in detail), and a rolling apparatus 30. A rolling step of rolling the resin fiber mixture into a flat plate shape (see FIG. 1 which is an explanatory diagram).

(1) Mixing Step The “mixing step” is a step of kneading and mixing the thermoplastic resin and the vegetable fiber.
In this mixing step, an extrusion type kneading and mixing apparatus excluding a mixer is used. Although this mixing apparatus is not specifically limited, What is necessary is just to be able to mix a lot of vegetable fibers with a thermoplastic resin, for example, the mixing apparatus described in FIG. 2, 3 can be used. When this specific mixing apparatus is used, a thermoplastic resin composition having higher fluidity can be more easily produced.

  This mixing apparatus [FIG. 2 (FIG. 2 is cited from FIG. 1 of the pamphlet of International Publication No. 04/076044 obtained from the Patent Electronic Library of the JPO)] and FIG. 3 (FIG. 3 is obtained from the Patent Electronic Library of the JPO. As the reference] (refer to FIG. 2 of the acquired International Publication No. 04/076044 pamphlet), the mixing device 1 described in the International Publication No. 04/076044 pamphlet is preferable. That is, the mixing apparatus 1 includes a material supply chamber 13, a mixing chamber 3 connected to the material supply chamber 13, and a rotary shaft 5 that is rotatably provided through the material supply chamber 13 and the mixing chamber 3. A screw blade 12 disposed on the rotary shaft 5 in the material supply chamber 13 and for conveying the mixed material of the thermoplastic resin and the plant fiber supplied to the material supply chamber 13 to the mixing chamber 3, and a mixing chamber It is preferable to include mixing blades 10a to 10f that are disposed on the rotary shaft 5 in the unit 3 and mix the mixed material.

  Using the mixing apparatus 1, the thermoplastic resin and the plant fiber are put into the material supply chamber 13, conveyed to the mixing chamber 3 by the screw blades 12, and the mixing blades 10a to 10f are rotated, so that the thermoplastic resin and the plant are rotated. Both fibers are pressed toward the inner wall of the mixing chamber 3, hit the inner wall, and pushed forward in the rotation direction of the mixing blades 10 a to 10 f, and the thermoplastic resin softens in a short time by the heat generated by the collision between the materials. And then melted, kneaded and mixed with the plant fiber. The mixture (thermoplastic resin composition) thus produced is imparted with excellent fluidity capable of injection molding, for example.

  The mixing blades 10a to 10f are opposed to the axial direction at a position spaced apart by a constant angle in the circumferential direction of the rotating shaft 5 and are attached to the rotating shaft 5 at an attachment angle such that the opposing interval becomes narrow in the rotating direction. It is arranged and is constituted by at least two mixing blades (10a to 10f). The angle of attachment of the mixing blades 10a to 10f with respect to the rotating shaft 5 is preferably the same from the root portion of the mixing blades 10a to 10f attached to the rotating shaft 5 to the distal end portion in the radial direction. The planar shape of the mixing blades 10a to 10f is preferably rectangular. Furthermore, it is more preferable that the mixing chamber 3 includes a mixing chamber cooling means that can circulate a cooling medium around the constituent walls. By setting it as such a structure, it can suppress that a mixing chamber heats up too much, and can prevent or at least suppress the thermal deterioration of a thermoplastic resin.

  Various conditions in the mixing step are not particularly limited. For example, the temperature during mixing is preferably controlled to 200 ° C. or less, particularly 150 ° C. or less, and further 120 ° C. or less, and the temperature of the outer wall surface of the mixing chamber is 50 ° C. As described above, it is particularly preferable to control the temperature at 60 ° C. or higher, and further 80 ° C. or higher. The time for reaching this temperature is preferably within 10 minutes, particularly within 5 minutes. By reaching the predetermined temperature in a short time, moisture can be rapidly evaporated and mixed, and deterioration of the thermoplastic resin can be suppressed more effectively. Furthermore, it is preferable that the time for maintaining the temperature range is within 15 minutes, particularly within 10 minutes. Moreover, it is preferable to control this temperature by the rotational speed of the mixing blade of the mixing apparatus. More specifically, it is preferable to control the peripheral speed at the tip of the mixing blade to be 5 to 50 m / sec. By controlling the peripheral speed within this range, the thermoplastic resin can be efficiently softened and mixed with the plant fiber more uniformly while being melted.

  Furthermore, the end point of this mixing is not particularly limited, but can be determined by a change in torque applied to the rotating shaft. That is, it is preferable to measure the torque applied to the rotating shaft and stop mixing after the torque reaches the maximum value. Thereby, a thermoplastic resin and a vegetable fiber can fully be mutually disperse | distributed. Further, it is more preferable to stop the mixing after the torque reaches the maximum value and starts to decrease. Furthermore, it is particularly preferable to stop the mixing when the torque reaches 40% or more, particularly 50 to 80% of the maximum torque. Thereby, while being able to disperse | distribute a thermoplastic resin and a vegetable fiber more fully mutually, a mixture (thermoplastic resin composition) can be taken out from the mixing chamber at the temperature of 160 degreeC or more, and thermoplasticity is mixed in a mixing chamber. It can prevent more reliably that the resin composition adheres and remains.

  Further, the “plant fiber” contained in the thermoplastic resin composition (a fiber having a form different from the plant fiber used as the raw fiber to be kneaded and mixed with the thermoplastic resin. In addition, the pulverization step and pelletization are performed. In the case where the step is provided, the fibers are further different in these steps.) The content of 50 to 95% by mass when the total of the thermoplastic resin and the plant fiber is 100% by mass. . This content is usually the same as the blending amount of the plant fiber blended into the thermoplastic resin during the production of the thermoplastic resin composition. That is, when the total amount of each of the thermoplastic resin and the plant fiber is 100% by mass, the amount of the plant fiber is 50 to 95% by mass. The plant fiber content (blending amount) is preferably 55 to 65% by mass. When the content (blending amount) of the plant fiber is 50 to 95% by mass, it can have a superior flexural modulus and the like and can be a preferable molded body from the viewpoint of practicality.

(2) Rolling process The "rolling process" is a process of rolling the resin fiber mixture discharged from the mixing apparatus.
The rolling may be a method using a pair of rolling rolls or a method using a press machine, but a method using a rolling roll capable of continuously rolling the resin fiber mixture continuously discharged from the mixing device. High efficiency and preferable. The rolling apparatus used in the rolling process includes a drawing roll for drawing the resin fiber mixture and a rolling roll for rolling the resin fiber mixture fed from the drawing roll into a flat plate shape, and the drawing roll is on the circumferential surface. A protrusion is erected. For example, as shown in FIG. 1, the resin fiber mixture C discharged from the mixing device 1 is called in, the drawing roll 301 for sending out the drawn resin fiber mixture C, and the lower side of the drawing roll 301 are arranged and called in A rolling device 30 provided with a rolling roll 302 for rolling the resin fiber mixture C that is called into the roll 301 and fed out can be used.

The drawing roll 301 is provided with protrusions on the peripheral surface in order to reliably draw the resin fiber mixture C without causing it to stay and to feed the resin fiber mixture C toward the rolling roll 302. This protrusion may be a dot-like protrusion or a linear protrusion. In the case of a point-like protrusion, the shape of the cross section is not particularly limited, and may be any of a circle, an ellipse, a polygon such as a triangle and a quadrangle. Moreover, it is preferable that this point-like protrusion has a protruding shape on the tip side. Furthermore, when it is a linear protrusion, the protrusion may be provided in the width direction of the roll or may be provided in an oblique direction, but if it is in the radial direction, the resin fiber mixture C is efficiently drawn in. It is not preferable because it cannot Each protrusion may be provided over the entire width of the roll or may be provided over a predetermined dimension in the width direction. Furthermore, it is preferable that this linear protrusion also has a protruding shape on the tip side (smaller in size than the peripheral surface side).
The clearance between the rolls is not particularly limited, and depends on the size of the resin fiber mixture, but the minimum dimension between the protrusions is 5 to 100 mm, particularly 10 to 50 mm, and the dimension between the peripheral surfaces is 10 to 150 mm, particularly 20 to 100 mm. can do. Moreover, when it is set as such clearance, the height of a protrusion will be 2.5-25 mm, especially 5-25 mm.

  On the other hand, the rolling roll 302 is a normal roll having a smooth peripheral surface, and is rolled when the resin fiber mixture C passes between pairs of rolls. The clearance between the rolls is preferably set according to the desired thickness of the rolled resin fiber mixture (rolled product C1). The clearance is determined by the thickness of the rolled product C1, the type of thermoplastic resin, and the resin fiber mixture C. It is preferable to set the temperature in consideration of the temperature. Moreover, in order to accelerate | stimulate cooling of the rolling product C1 and prevent heat storage more reliably, it is preferable that the rolling roll 302 has a cooling function. Such a cooling function can be normally imparted to the refrigerant flow path provided in the roll by, for example, air cooling for circulating air and water cooling for circulating water. Although the temperature of a refrigerant | coolant is not specifically limited, It is not necessary to make it too low temperature, and can be 0-50 degreeC, especially 10-30 degreeC.

The thickness of the rolled product C1 is not particularly limited, and the heat and heat of the rolled product C1 which is discharged from the mixing device and is usually rolled at 220 to 240 ° C. and high temperature is sufficiently cooled. Good. Moreover, the thickness should just be the thickness which can be efficiently grind | pulverized with a general grinder. This thickness can be, for example, 1 to 10 mm, in particular 2 to 8 mm. In this case, the clearance between the rolling rolls 302 can be 1 to 10 mm, particularly 2 to 8 mm. Usually, the thickness of the rolled product C1 is substantially the same as the clearance between the rolling rolls 302.
In addition, the rolled product C1 obtained by rolling the resin fiber mixture C into a flat plate shape in the rolling process is usually pulverized or pulverized and pelletized to be used as a raw material of a molded body.

  The diameter and the rotational speed of each of the attracting roll 301 and the rolling roll 302 are not particularly limited, and the delivery speed of the rolled product C1 from the rolling roll 302 is 0.2 to 5 m / min, particularly 0.5 to 3 m / min. Further, the diameter and the rotation speed are preferably 0.7 to 2 m / min. For example, the diameter of the attracting roll 301 can be 20 to 300 mm, particularly 30 to 200 mm, and the rotation speed (circumferential speed at the tip of the protrusion) can be 0.2 to 5 m / min, particularly 0.5 to 3 m / min. The diameter of the rolling roll 302 can be 50 to 500 mm, particularly 100 to 350 mm, and the rotation speed (circumferential speed) can be 0.2 to 5 m / min, particularly 0.5 to 3 m / min.

(3) Grinding step The method for producing a thermoplastic resin composition of the present invention may include other steps except for the mixing step and the rolling step. As this other process, the grinding | pulverization process which grind | pulverizes the rolling product C1 and makes a grinding | pulverization mixture is mentioned. When this crushing step is provided, the crushing apparatus is not particularly limited as long as the rolled product C1 can be pulverized efficiently. As such an apparatus, a pulverizing apparatus generally used for pulverizing a resin composition can be used. For example, a Z series grinder with high grinding efficiency manufactured by Horai Co., Ltd. can be used. Further, the shape and particle size of the particles of the pulverized mixture are not particularly limited, and operations such as sizing are not particularly required, and the pulverized mixture can be used as a raw material for a molded body. The particle diameter (maximum dimension) is preferably 1 to 10 mm, particularly preferably 3 to 8 mm. If the particle diameter is 1 to 10 mm, it is easy to handle and can be easily supplied to a molding machine such as an injection molding machine.

(4) Pelletization step (a) Pelletization of thermoplastic resin composition The pulverized mixture obtained by the pulverization step can be used as it is as a raw material of the molded body, but is preferably used after being pelletized. Is formed into pellets to facilitate molding such as injection molding. The pelletizing method is not particularly limited. For example, a pulverizing apparatus and a pelletizing apparatus can be arranged in parallel and pelletized continuously with the pulverization. Pelletization can also be performed without reheating the pulverized mixture, and the pulverized mixture discharged from the pulverizer can be melt-kneaded by an extruder or the like and extruded to be pelletized.

  The pulverized mixture is preferably heated and pelletized without heating. Thus, without heating, by pressing and solidifying into pellets, the thermal history to the thermoplastic resin composition can be reduced compared to pelletizing the pulverized mixture using an extruder or the like, The mechanical properties of a molded article molded using this thermoplastic resin composition can be further improved.

  Any apparatus and means may be used in the step of pressing and solidifying without heating, and it is particularly preferable to use pelletization by various compression molding methods. Examples of the compression molding method include a roller molding method and an extruder molding method. Among these, the roller molding method is a method using a roller molding machine, in which the pulverized mixture is pressed into the die by a roller that rotates in contact with the die, and then extruded from the die and pelletized. Examples of the roller type molding machine include a disk die type (roller disk die type molding machine) and a ring die type (roller ring die type molding machine), which have different die shapes. On the other hand, the extruder type molding method is a method using an extruder type molding machine, in which a pulverized mixture is pressed into a die by rotation of a screw auger, and then extruded from the die to be pelletized. Among these compression molding methods, a method using a roller disk die type molding machine with high compression efficiency is more preferable.

Furthermore, in this method, it is particularly preferable to pelletize by using the following specific roller disk die type molding machine 90 (see FIG. 4 showing the main part). That is, a disk die 91 having a plurality of through holes 911, a press roller 92 that rolls on the disk die 91 and pushes an uncompressed material (a pulverized mixture) into the through holes 911, and drives the press roller 92. It is particularly preferable to use a roller disk die molding machine provided with the main rotating shaft 93. In this molding machine, the disk die 91 has a main rotation shaft insertion hole 912 that penetrates in the same direction as the through hole 911, and the main rotation shaft 93 is inserted through the main rotation shaft insertion hole 912 and the main rotation shaft 93. And a press roller fixing shaft 94 provided perpendicularly to the main body. The press roller 92 is rotatably supported by the press roller fixed shaft 94 and rolls on the disk die 91 as the main rotating shaft 93 rotates.
In this roller disk die type molding machine 90, in addition to the above configuration, it is more preferable that the surface of the press roller 92 is provided with unevenness 921. It is more preferable that a cutting blade 95 that is rotated in accordance with the rotation of the main rotating shaft 93 is provided.

  In the roller disk die type molding machine 90, for example, in FIG. 4, the pulverized mixture charged from above the main rotating shaft 93 is caught by the unevenness 921 provided in the press roller 92 and pushed into the through hole 911, and the back surface of the disk die 91 Extruded in a string form from the side. The pulverized mixture in the form of a string is cut into an appropriate length by a rotating cutting blade 95, pelletized, and dropped downward to be collected. Moreover, the shape and dimension of the pelletized thermoplastic resin composition are not particularly limited, but a columnar shape such as a columnar shape is preferable. Furthermore, the maximum dimension is preferably 1 mm or more (usually 20 mm or less), more preferably 1 to 10 mm, and particularly preferably 2 to 7 mm.

(B) Pelletization of plant fibers When pelletizing plant fibers, the pelletizing apparatus is not particularly limited, but the above-mentioned roller disk die type molding machine is used in the same manner as the pelletization of the thermoplastic resin composition of (a). Can be used. By pelletizing the plant fiber in this way, the difference in bulk density between the plant fiber and the thermoplastic resin can be reduced, workability is improved, and uneven distribution of each material during mixing can also be suppressed. it can. Moreover, it can be set as the thermoplastic resin composition by which the vegetable fiber and the thermoplastic resin were disperse | distributed more uniformly mutually, and the mechanical strength of the molded object using this composition can be improved more.

(5) Continuous process from mixing step to pelletizing step The mixing step and the rolling step are steps in which the mixing device 1 and the rolling device 30 are arranged in parallel, continuously mixed, and rolled as shown in FIG. It is preferable that That is, the resin fiber mixture C discharged from the mixing apparatus 1 is dropped toward the attracting roll 301 included in the rolling apparatus 30 and is attracted between the rolls. It is preferable to send out toward the rolling roll 302 arrange | positioned below, and to roll between rolls to make the flat rolled product C1 of predetermined thickness.

  The flat rolled product C1 obtained in the rolling step is usually pulverized or pulverized and pelletized to be used as a raw material for a molded body. When pulverizing in this way, or when pulverizing and pelletizing, the pulverizing step and the pelletizing step are preferably continuous with the rolling step. For example, the rolled product C1 discharged from the rolling device 30 can be pulverized to some extent [for example, even if the temperature is lowered to 100 ° C. or lower and room temperature (20 to 30 ° C.), there is no particular problem. ], The temperature may be directly fed into the pulverizer 50 as it is. Further, when the rolled product C1 is at a higher temperature (for example, 110 to 150 ° C., particularly 120 to 130 ° C.), the rolled product C1 is radiated while being conveyed by the belt conveyor 40 as shown in FIG. You may throw into the apparatus 50. FIG.

  The material of the belt conveyor 40 is not particularly limited, and may be any of rubber or metal. Further, if the belt conveyor 40 is made of metal and mesh-like, the cooling of the rolled product C1 is further promoted, so that the rolled product C1 can be pulverized even if the rolling roll 302 does not have a cooling function. The temperature can be lowered to any extent. Further, the length of the belt conveyor 40 is not particularly limited, and may be 1 to 5 m, particularly 2 to 4 m. Moreover, the moving speed of the belt conveyor 40 is not particularly limited. The moving speed of the belt conveyor 40 is such that the time during which the rolled product C1 is dissipated while moving on the belt conveyor 40 is 10 to 60 seconds, particularly 20 to 40 seconds. It is preferable to set the length of the belt conveyor 40 in consideration of the length.

  Further, when the pulverized mixture is pelletized, the pulverizing device 50 and the pelletizing device 90 are arranged in parallel, and the pulverized mixture obtained by pulverization by the pulverizing device 50 is conveyed in the transport duct hose 60 to be contained in the cyclone 70. It is preferable that the dust is collected by collecting the dust, and then the air is cut by the rotary valve 80 and the pellets are put into the pelletizing device 90 to be pelletized.

[3] Method for Producing Molded Body A thermoplastic resin composition produced by the method of the present invention (preferably a pulverized pulverized mixture or a pellet obtained by pelletizing the pulverized mixture after rolling) is formed by injection molding, extrusion. The molded body can be formed by various molding methods such as molding and compression molding. This thermoplastic resin composition has excellent fluidity even though it contains a large amount of plant fiber, and can therefore be used for injection molding that requires particularly sufficient fluidity. If the thermoplastic resin composition is pelletized at the time of this injection molding, the measurement time, the injection time, etc. can be shortened. As a result, the molding cycle can be shortened and the molding efficiency can be improved. Also, the apparatus and molding conditions used for various moldings such as injection molding are not particularly limited, and may be appropriately selected and set depending on the type of thermoplastic resin, the shape of the molded body, the use, and the like.

  The shape and dimensions of the molded body are not particularly limited, and the use is not particularly limited. Examples of the molded body include interior materials, exterior materials, and structural materials such as automobiles, railway vehicles, ships, and airplanes. Among these, automotive materials include interior materials, instrument panels, exterior materials, etc., specifically, door base materials, package trays, pillar garnishes, switch bases, quarter panels, armrest core materials, door trims. Seat structural materials, seat backboards, ceiling materials, console boxes, dashboards, instrument panels, deck trims, bumpers, spoilers, cowlings and the like. Furthermore, examples of other uses other than the above-described automobiles include interior materials such as buildings and furniture, exterior materials, and structural materials. For example, a door cover material for a building, a door structure material, a cover material for various furniture such as a desk, a chair, a shelf, and a bag, a structural material, and the like. Still other examples include packaging bodies, containers such as trays, protective members, partition members, and the like.

Hereinafter, the present invention will be described specifically by way of examples.
[1] Production of thermoplastic resin composition Example 1
(1) Production of thermoplastic resin composition (see FIG. 1)
360 g of kenaf fiber [fiber length: 5 to 7 mm (the fiber from which the raw fiber was cut)] and 240 g of polypropylene (manufactured by Nippon Polypro Co., Ltd., trade name “NOVATEC NBC03HR”, melt flow rate; 30 g / 10 min) (The kenaf fiber is 60% by mass in terms of mass ratio) is introduced into the material supply chamber 13 of the mixing apparatus 1 (apparatus described in WO2004-076044) in FIG. 3, the mixing blades (10a to 10f in FIG. 3) were rotated at a rotational speed of 1750 rpm, kneaded and mixed. Then, the load (torque) applied to the mixing blade increased, and after 4 seconds had elapsed since reaching the maximum value, the mixing was stopped and the resin fiber mixture C was discharged from the mixing apparatus 1. The discharged mass resin fiber mixture C having a maximum size of 10 to 20 cm was as high as 220 to 240 ° C.

(3) Rolling, crushing, and pelletizing The lump-shaped resin fiber mixture C produced and discharged in the above (1) is a drawing roll 301 of the rolling device 30 disposed below the discharge port [the roll diameter is 50 mm. The clearance (between protrusions) is 20 mm. Then, it is fed toward a rolling roll 302 (with a roll diameter of 150 mm and a clearance of 5 mm) in which cooling water of 20 ° C. is circulated, and has a thickness of about 5 mm. The rolled product C1 was rolled into a flat plate (the delivery speed of the rolled product C1 is 1.5 m / min), and then the rolled product C1 was dropped onto one end of the conveyor 40 and conveyed while dissipating heat. Thereafter, the temperature was lowered (the temperature was about 100 ° C.), and the rolled product C1 (the weight of one piece was about several tens to 100 g) was pulverized from the other end of the conveyor 40 (made by Horai Co., Ltd.). , Type “Z10-420”), pulverized, and passed through a screen having an opening of 5 mm. Next, the obtained pulverized mixture is transported through a transport duct hose 60 and charged into a cyclone 70 for dust collection, and then air-cut by a rotary valve 80 and roller disk die pelletizer 90 (Kikukawa). Steel type, type “KP280”, using a die with a through-hole diameter of 4.2 mm and a thickness of 25 mm) to form a cylindrical pellet having a diameter of about 4 mm and a length of about 5 mm. And dried for 24 hours at 100 ° C. to produce pellets of the thermoplastic resin composition.

[2] Characteristic evaluation of thermoplastic resin composition The pellets of the thermoplastic resin composition of Example 1 obtained in [1] above were dried in an oven at 100 ° C. for 5 hours, and then an injection molding machine (Sumitomo). By a heavy machine industry, type “SE100DU”), injection molding was performed under conditions of a cylinder temperature of 190 ° C. and a mold temperature of 40 ° C. to produce a test piece having a length of 80 mm, a width of 10 mm, and a thickness of 4 mm. Was subjected to a bending test to calculate the bending strength and the bending elastic modulus. In addition, injection molding was similarly performed using a bar flow mold, and the flow length was evaluated. As a result, the flexural modulus was 5700 MPa and the bar flow length was 200 mm. Thus, it can be seen that the thermoplastic resin composition of Example 1 has sufficient bending properties and excellent fluidity with the bar flow length as an index.

  The method for producing a thermoplastic composition of the present invention can be used in a wide range of applications such as automobile-related fields and construction-related fields, and is used for interior materials, exterior materials, and structural materials for automobiles, railway vehicles, ships, airplanes, and the like. In particular, it can be suitably used in the field of automobile-related products such as automotive interior materials, automotive instrument panels, and automotive exterior materials.

  DESCRIPTION OF SYMBOLS 1; Mixing device, 3; Mixing chamber, 5; Rotating shaft, 10 and 10a-10f; Mixing blade, 12; Spiral blade, 13; Material supply chamber, 30; Rolling device, 301; , 40; Conveyor for conveyance, 50; Grinding device, 60; Duct hose for conveyance, 70; Cyclone, 80; Rotary valve, 90; Roller disk die molding machine, 91; Disc die, 911; Rotating shaft insertion hole, 92; press roller, 921; uneven portion, 93; main rotating shaft, 94; press roller fixed shaft, 95; cutting blade.

Claims (9)

A method for producing a thermoplastic resin composition comprising a thermoplastic resin and plant fibers, wherein the total amount of the thermoplastic resin and the plant fibers is 100% by mass, and the plant fibers are 50 to 95% by mass. There,
Kneading and mixing the thermoplastic resin and the vegetable fiber to mix and make a resin fiber mixture, and rolling the resin fiber mixture to make a flat rolled product ,
The rolling device used in the rolling step includes a drawing roll for drawing the resin fiber mixture, and a rolling roll for rolling the resin fiber mixture fed from the drawing roll into a flat plate shape,
A process for producing a thermoplastic resin composition, wherein the attracting roll has protrusions on its peripheral surface .   The rolling roll is disposed below the attracting roll,
  2. The method for producing a thermoplastic resin composition according to claim 1, wherein the resin fiber mixture delivered from the attracting roll is supplied to the rolling roll while falling downward. 3. The mixing device used for the kneading and mixing includes a mixing chamber in which the mixing is performed and a mixing blade disposed in the mixing chamber,
The method for producing a thermoplastic resin composition according to claim 1 or 2 , wherein the thermoplastic resin that has been heated and melted by rotation of the mixing blade and the vegetable fiber are kneaded and mixed in the mixing chamber. . Manufacturing method of the rolling rolls of the thermoplastic resin composition of claim 1 having a cooling function.   The manufacturing method of the thermoplastic resin composition of any one of Claims 1 thru | or 4 provided with the grinding | pulverization process which grind | pulverizes the resin fiber mixture obtained in the said mixing process to make a grinding | pulverization mixture.   The method for producing a thermoplastic resin composition according to claim 5, further comprising a pelletizing step of pressing and solidifying the pulverized mixture. The said vegetable fiber is a kenaf fiber, The manufacturing method of the thermoplastic resin composition of any one of Claims 1 thru | or 6.   The method for producing a thermoplastic resin composition according to any one of claims 1 to 7, wherein the thermoplastic resin is a polypropylene resin and an acid-modified polypropylene resin.   The production of the thermoplastic resin composition according to claim 8, wherein the acid-modified polypropylene resin is 1 to 30% by mass when the total of the polypropylene resin and the acid-modified polypropylene resin is 100% by mass. Method.

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