JP5211571B2 - Method for producing thermoplastic resin composition and method for producing molded body - Google Patents

Description

  The present invention relates to a method for producing a thermoplastic resin composition and a method for producing a molded body. More specifically, the present invention relates to a method for producing a thermoplastic resin composition containing a thermoplastic resin and cellulose nanofibers, and a method for producing a molded body using the thermoplastic resin composition.

In recent years, materials using biological resources such as plants and animals and their technologies have attracted attention from the viewpoint of reducing carbon dioxide emissions and protecting the environment. In particular, attempts to switch from resins using mineral resources such as petroleum to resins using biological resources, and using mineral resources by mixing resins obtained from mineral resources with reinforcing agents obtained from biological resources Attempts have been made to reduce the amount. However, resins obtained from mineral resources have been imparted with excellent properties through various physical property controls. On the other hand, resins obtained from biological resources, such as polylactic acid, are improved in heat resistance and increased in crystallization speed to achieve better physical properties. Some parts are still inferior in properties compared to the obtained resin.
With respect to this problem, as disclosed in the following Patent Document 1 and Patent Document 2 below, a technique of mixing natural materials is known from the viewpoint of imparting higher strength to the resin.

JP 2004-50482 A JP 2006-206913 A

The above Patent Documents 1 and 2 are both techniques for obtaining an excellent strength improvement effect. However, mixing a natural material into a resin is difficult to mix due to a large specific gravity difference between the resin and the natural material. There is. Further, although the strength of the resin can be supplemented by using a large amount of natural material, there is an aspect that the properties such as moldability which are excellent with the resin alone are deteriorated. For this reason, there is a need for a technique that can achieve a high characteristic improvement effect with a smaller amount of addition, and a technique that can be used in combination with mixing of natural materials.
The present invention has been made in view of the above prior art, and a method for producing a thermoplastic resin composition from which a thermoplastic resin composition containing a thermoplastic resin and cellulose nanofibers is obtained, and the thermoplastic resin composition. It aims at providing the manufacturing method of the molded object using this.

This inventor examined mixing with resin and a cellulose nanofiber. Cellulose nanofibers can only maintain a defibrated state as a dispersion coexisting with a dispersion medium such as water, and once the dispersion medium is lost, the fibers are aggregated into a lump, and then the dispersion medium is added. Even the defibrated state cannot be restored. Furthermore, since it has extremely high hydration properties, it usually exhibits a clay shape, and even an aqueous dispersion having a solid content concentration of about 10% by mass has high viscosity. For this reason, it is difficult to form an aqueous dispersion having a high solid content concentration. In mixing with a resin, mixing with a large amount of water is performed, and operations such as normal kneading cannot be performed.
On the other hand, the present inventor has found that cellulose nanofibers can be dispersed and contained in the thermoplastic resin by directly mixing the thermoplastic resin and the aqueous dispersion, thereby completing the present invention. It was.

That is, the present invention is as follows.
(1) A method for producing a thermoplastic resin composition in which an aqueous dispersion of cellulose nanofibers and a thermoplastic resin are mixed with a stirrer to obtain a thermoplastic resin composition ,
The stirrer includes a mixing chamber for performing the mixing,
A method for producing a thermoplastic resin composition, comprising vaporizing water contained in the aqueous dispersion by the mixing and pressurizing the mixing chamber.
( 2 ) The said thermoplastic resin is a manufacturing method of the thermoplastic resin composition as described in said (1) which is a biodegradable resin.
( 3 ) The method for producing a thermoplastic resin composition according to (1) or ( 2 ), wherein a plant material is further mixed with the aqueous dispersion of the cellulose nanofibers and the thermoplastic resin with the agitator.
( 4 ) The method for producing a thermoplastic resin composition according to ( 3 ), wherein the plant material is kenaf core.
( 5 ) A molded article obtained by extrusion molding or injection molding a thermoplastic resin composition obtained by the production method according to any one of (1) to ( 4 ) above. Production method.

According to the method for producing a thermoplastic resin composition of the present invention, an aqueous dispersion of cellulose nanofibers and a thermoplastic resin can be directly mixed. In particular, mixing can be performed in one step, and the mass productivity is excellent. Further, the obtained thermoplastic resin can improve the strength as compared with the case of using only the thermoplastic resin, and is particularly excellent in the effect of improving the bending property.
Since the pressure of the mixing chamber water is vaporized contained in the aqueous dispersion, it can be performed more quickly and efficiently mixed.
When the thermoplastic resin is a biodegradable resin, the environmental impact is small, non-mineral resources can be used as raw materials, and the use of mineral resources can be suppressed while obtaining practical properties such as high mechanical strength. .
When plant materials are mixed with an aqueous dispersion of cellulose nanofibers and a thermoplastic resin with a stirrer, the specific gravity is extremely small compared to the cellulose nanofibers and thermoplastic resins, and more difficult to mix. The plant material can be mixed in one step and is particularly excellent in mass productivity. Further, the obtained thermoplastic resin can improve the strength as compared with the case of using only the thermoplastic resin, and is particularly excellent in the effect of improving the bending property.
When the plant material is a kenaf core, it is possible to obtain a thermoplastic resin composition that can form a molded article that is lighter and particularly excellent in flexural modulus. Kenaf is an annual plant that grows very fast and has excellent carbon dioxide absorption, so it can contribute to reducing the amount of carbon dioxide in the atmosphere and effectively using forest resources.
According to the method for producing a molded article of the present invention, it is possible to obtain a molded article having excellent strength, containing cellulose nanofibers and a thermoplastic resin.

[1] A method for producing a thermoplastic resin composition A method for producing a thermoplastic resin composition in which an aqueous dispersion of cellulose nanofibers and a thermoplastic resin are mixed with a stirrer to obtain a thermoplastic resin composition ,
The stirrer includes a mixing chamber for performing the mixing,
A method for producing a thermoplastic resin composition, comprising vaporizing water contained in the aqueous dispersion by the mixing and pressurizing the mixing chamber .

The “cellulose nanofiber” is a fiber made of cellulose and / or a derivative of cellulose, and the diameter of the single fiber is not particularly limited, but is 4 to 2000 nm. The length of the single fiber is not particularly limited, but is 100 to 1000 μm. Further, in the aqueous dispersion, the single fiber may be formed into a fibrous shape by collecting a plurality of filaments. Cellulose nanofibers have a strong hydration property and can stably maintain a dispersed state (dispersed state) by being hydrated in an aqueous medium.
As a cellulose nanofiber used by this invention, the diameter of a single fiber has preferable 20-30 nm. The length of the single fiber is not particularly limited, but is preferably 0.1 to 1000 μm (more preferably 0.1 to 100 μm). These ranges of single-fiber cellulose nanofibers are particularly suitable for mixing by the present method.

  The aqueous dispersion of cellulose nanofibers may contain fibers having a diameter of a single fiber exceeding 2.0 μm, but is 10% by mass or less (preferably 5% by mass) with respect to the entire aqueous dispersion of cellulose nanofibers. Or less). If it is this range, the reinforcement effect by containing a cellulose nanofiber can be acquired more effectively.

  The kind of cellulose nanofiber used for this method is not specifically limited, The manufacturing method is also not specifically limited. For example, as cellulose nanofibers, (1) fiber raw materials (pulp, etc.) obtained by microfibrillation with a homogenizer (high pressure homogenizer, high pressure homogenizer), (2) fiber raw materials (pulp, etc.) Obtained by microfibrillation with a friction machine (grinder, grinder, etc.), (3) obtained by microfibrillation of a fiber raw material (pulp, etc.) with a refiner (conical refiner, disc refiner, etc.), (4 And the like produced by various bacteria (bacterial cellulose). Further, the fiber raw material (pulp or the like) may be subjected to chemical treatment (phosphate esterification treatment, acetylation, cyanoethylation, etc.) and then various microfibrillations. These various cellulose nanofibers may be used alone or in combination of two or more.

Moreover, as a fiber raw material of a cellulose nanofiber, any of a plant-derived fiber raw material, an animal-derived fiber raw material, and a microorganism-derived fiber raw material may be used, or two or more of these may be used in combination. . Examples of plant-derived fiber materials include pulp and plant materials. Among these, recycled pulp, kraft pulp and mechanical pulp are mentioned as pulp. These may use only 1 type and may use it in combination of 2 or more type. Furthermore, the plant material mentioned later can be applied as it is as the plant material. Examples of the animal-derived fiber raw material include cellulose derived from sea squirt. Furthermore, bacterial cellulose is mentioned as a fiber raw material derived from microorganisms.
In addition, the cellulose nanofiber referred to in the present invention includes various fine fibers referred to as microfibril cellulose, microfibril-like fine fiber, microfiber cellulose, microfibrillated cellulose, super microfibril cellulose, etc. It is meant to include fibers in which at least one of these is further refined.

  The “water dispersion” is a dispersion containing the cellulose nanofibers, and is a dispersion containing water as a dispersion medium. The total amount of this dispersion medium is preferably water, but other liquids (for example, lower alcohols having 3 or less carbon atoms) that are partially compatible with water can also be used. The solid content concentration of the aqueous dispersion is not particularly limited, but is preferably 50% by mass or less (more preferably 40% by mass or less). Moreover, it is preferable that it is 1 mass% or more (more preferably 5 mass% or more).

  The blending amount of cellulose nanofibers (in terms of solid content) in this method is not particularly limited, but when the total of cellulose nanofibers and thermoplastic resin is 100% by mass, cellulose nanofibers are 1% by mass or more (more preferably). Is preferably 5% by mass or more and usually 70% by mass or less. In this range, the strength improvement effect by mixing cellulose nanofibers with a thermoplastic resin can be obtained, and in particular, the bending strength and the bending elastic modulus can be effectively improved. Further, the blending amount is particularly preferably 15% by mass or more. By setting it as 15 mass% or more, a remarkably high reinforcement effect can be acquired rather than with respect to the compounding quantity less than it. In addition, content of the cellulose nanofiber contained in the thermoplastic resin composition obtained by this method is usually the same as the blending amount of the cellulose nanofiber.

The “thermoplastic resin” is not particularly limited, and various types can be used. For example, polyolefin (polypropylene, polyethylene, etc.), polyester resin {(aliphatic polyester resin such as polylactic acid, polycaprolactone), (aromatic polyethylene resin such as polyethylene terephthalate)}, polystyrene, polyacrylic resin (methacrylate, acrylate, etc.) ), Polyamide resin, polycarbonate resin, polyacetal resin and the like. These may use only 1 type and may use 2 or more types together.
Among these, at least one of polyolefin and polyester resin is preferable. Of the above polyolefins, polypropylene is more preferred.

On the other hand, among polyester resins, polyester resins having biodegradability (hereinafter also simply referred to as “biodegradable resins”) are preferable. Biodegradable resins include (1) homopolymers of hydroxycarboxylic acids such as lactic acid, malic acid, glucose acid and 3-hydroxybutyric acid, and co-polymerization using at least one of these hydroxycarboxylic acids Caprolactone-based aliphatic polyesters, such as hydroxycarboxylic acid-based aliphatic polyesters, (2) polycaprolactone, and copolymers of at least one of the above hydroxycarboxylic acids with caprolactone, (3) poly And dibasic acid polyesters such as butylene succinate, polyethylene succinate and polybutylene adipate.
Among these, polylactic acid, a copolymer of lactic acid and other hydroxycarboxylic acid excluding lactic acid, polycaprolactone, and a copolymer of caprolactone with at least one of the above hydroxycarboxylic acids are particularly preferable. Polylactic acid is preferred.
These biodegradable resins may be used alone or in combination of two or more.
The lactic acid includes L-lactic acid and D-lactic acid, and these lactic acids may be used alone or in combination.

  The blending amount of the thermoplastic resin in this method is not particularly limited, but when the total of the cellulose nanofibers and the thermoplastic resin is 100% by mass, the thermoplastic resin is 99% by mass or less (more preferably 95% by mass or less). And usually 30% by mass or more). In this range, the strength improvement effect by mixing cellulose nanofibers with a thermoplastic resin can be obtained, and in particular, the bending strength and the bending elastic modulus can be effectively improved. In addition, content of the thermoplastic resin contained in the thermoplastic resin composition obtained by this method is the same as the compounding quantity of the said thermoplastic resin normally.

  The “stirrer” is a stirrer described in International Publication No. 04/076044, and is an apparatus for mixing an aqueous dispersion of cellulose nanofibers and a thermoplastic resin. This stirrer 10 (refer to FIG. 1 and FIG. 2 below) is a stirrer capable of pressurizing a mixing chamber in which water contained in an aqueous dispersion is vaporized to mix cellulose nanofibers and a thermoplastic resin. It is. That is, a pressure vessel is provided as the mixing chamber 11.

Further, as such a stirrer 10, a material supply chamber 12, a mixing chamber 11 connected to the material supply chamber 12, and the material supply chamber 12 and the mixing chamber 11 are rotatably provided. The rotating shaft 13, the spiral blade 14 disposed on the rotating shaft 13 in the material supply chamber 12 and transporting the mixed material supplied to the material supply chamber 12 to the mixing chamber 11, and the mixing A stirrer provided on the rotating shaft 13 in the chamber 11 and provided with a mixing blade 15 for mixing the mixed material is preferable.
By using this stirrer, steam is efficiently discharged from the mixing chamber to the outside of the stirrer while efficiently evaporating the water contained in the water dispersion (steam leakage to ensure safety is good). It is held in the mixing chamber, and the mixing chamber can be maintained at a high temperature and high pressure. As a result, it is considered that the thermoplastic resin is softened or melted and the defibrated state of the cellulose nanofiber can be maintained, and the thermoplastic resin and the cellulose nanofiber can be mixed by the mixing blade. The mixed material means all materials to be mixed in the mixing chamber. Further, the spiral blade is preferably a spiral blade that can prevent the vapor generated in the mixing chamber from leaking to the material supply chamber side.

In addition, the mixing blade 15 is arranged on the rotary shaft 13 at an attachment angle so as to face each other in the axial direction at a portion of the rotary shaft 13 at a constant angular interval in the circumferential direction and so that the opposing interval becomes narrow in the rotational direction. It is constituted by at least two mixing blades (15a to 15f) provided, and the mounting angle of the mixing blade 15 with respect to the rotary shaft 13 is radially outward from the root portion of the mixing blade 15 attached to the rotary shaft 13. It is preferable to be the same up to the distal end, and it is preferable that the mixing blade 15 has a rectangular plate shape.
With this configuration, it is considered that the mixing blade can be struck and pushed so as to press the mixed material toward the inner wall of the mixing chamber. For this reason, the mixed material in the mixing chamber can be efficiently heated, and the water contained in the water dispersion can be vaporized to pressurize the mixing chamber. Further, with this configuration, the cellulose nanofibers and the thermoplastic resin can be mixed more efficiently under suitable conditions in the mixing chamber.

More preferably, the mixing chamber further includes a mixing chamber cooling means that can circulate a cooling medium through the walls constituting the mixing chamber. With this configuration, an excessive temperature rise in the mixing chamber can be suppressed and decomposition of the thermoplastic resin can be prevented.
Furthermore, the bearing portion supporting the rotating shaft is provided with a groove for venting the mixing chamber and the outside of the mixing chamber, and air outside the mixing chamber can be sucked into the mixing chamber through the groove, and the mixing is performed in the mixing chamber. It is particularly preferred that sometimes dehydrated components that have been dehydrated due to heat generation due to shearing, friction and / or compression of the material can be discharged, and it is further preferred that the groove is helical. With this configuration, it is possible to prevent the mixing chamber from being excessively pressurized and perform pressure release in the mixing chamber. For this reason, a thermoplastic resin composition can be manufactured more safely.

  The “mixing” is performed using a stirrer. It is not certain what kind of phenomenon occurs in this mixing, but it is considered that the following phenomenon occurs. That is, each mixed material is heated by shearing, friction and / or compression by the mixing blade in the mixing chamber, and the water contained in the water dispersion is vaporized. However, since there is no steam discharge path to the outside of the mixing chamber (the groove provided in the bearing of the rotating shaft can be formed as a discharge path, but the pressure inside the mixing chamber does not decrease to normal pressure) The mixing chamber is pressurized. Thereby, it is thought that the cellulose nanofiber which should not be able to maintain a defibrated state, if water is vaporized from an aqueous dispersion normally, can maintain a defibrated state. Further, when the temperature in the mixing chamber is raised to the softening or melting temperature of the thermoplastic resin, the thermoplastic resin is softened or melted in the mixing chamber. Thereby, it is thought that a thermoplastic resin and a cellulose nanofiber can be physically mixed with a mixing blade. Furthermore, even when water having a very low affinity with the thermoplastic resin is present at the time of mixing, since it exists as a vapor, there is little intrusion into the mixed thermoplastic resin, and cellulose nanofibers and the thermoplastic resin It is thought that it does not inhibit the mixing with.

Various conditions in this mixing are not particularly limited, but it is preferable to carry out the pressurization in the mixing chamber by evaporating the water contained in the aqueous dispersion as described above.
The pressure in the mixing chamber at the time of mixing is not particularly limited, but is a pressure exceeding normal pressure (for example, 0.1013 MPa). Although the upper limit of the pressure is not particularly limited, it is preferably 100 MPa or less (more preferably 7 MPa or less, further preferably 5 MPa or less, particularly preferably 3 MPa or less). Further, the temperature is not particularly limited, but the temperature of the outer wall of the mixing chamber is preferably controlled to 200 ° C. or lower (more preferably 150 ° C. or lower, more preferably 120 ° C. or lower), and more preferably 50 ° C. or higher (more preferably). 60 ° C. or higher, more preferably 80 ° C. or higher). The temperature is preferably reached within 10 minutes (more preferably within 5 minutes). The temperature can be rapidly evaporated and the above mixing can be performed by raising the temperature in a short time, and the time for dissociating the cellulose nanofibers from the dispersion medium can be shortened to easily maintain the defibrated state. The deterioration of the resin can also be suppressed. Further, the temperature range is preferably within 15 (more preferably within 10 minutes).

Moreover, it is preferable to control the said temperature by controlling the rotational speed of the mixing blade of a stirrer. More specifically, it is preferable to control the rotation speed at the tip of the mixing blade to be 5 m / sec to 50 m / sec. By controlling within this range, the vaporization efficiency of water in the aqueous dispersion can be particularly improved, and the cellulose nanofibers and the thermoplastic resin can be mixed more strongly.
In addition to the mixing blade, the temperature and pressure can be controlled by adding the above-described mixing chamber cooling means and / or rotating shaft cooling means.

  Furthermore, although the end point in this mixing is not specifically limited, it 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 cellulose nanofiber can be mixed in a thermoplastic resin with sufficient dispersibility. Furthermore, it is more preferable to stop the mixing after the torque starts to decrease after reaching the maximum value of the torque. It is particularly preferable to stop the mixing in a torque range of 40% or more (particularly preferably 50 to 80%) with respect to the maximum torque. As a result, the cellulose nanofibers can be mixed in the thermoplastic resin with better dispersibility, and the mixture (thermoplastic resin composition) can be taken out from the inside of the mixing chamber at a temperature of 160 ° C. or more. It can prevent more effectively that a composition adheres and remains.

In the thermoplastic resin composition of the present invention, components other than the aqueous dispersion of cellulose nanofibers and the thermoplastic resin can be mixed. Other ingredients include plant material.
That is, it can be set as the manufacturing method of the thermoplastic resin composition which mixes a vegetable material with a stirrer further with the aqueous dispersion and cellulose resin of a cellulose nanofiber.
This plant material includes kenaf, jute hemp, manila hemp, sisal hemp, husk, cocoon, cocoon, banana, pineapple, coconut, corn, sugar cane, bagasse, palm, papyrus, cocoon, esparto, saprograss, wheat, rice, bamboo, Examples include plant materials obtained from various plants such as various conifers (such as cedar and cypress), broad-leaved trees, and cotton. This plant material may use only 1 type and may use 2 or more types together.

Moreover, the adoption site | part of the plant body used as said plant material is not specifically limited, Any site | part which comprises plant bodies, such as a wood part, a non-wood part, a leaf part, a stem part, and a root part, may be sufficient. Furthermore, only plant material obtained from a specific part may be used, or plant materials obtained from two or more different parts may be used in combination.
In addition, the kenaf in this invention is an early-growing annual grass which has a wooden stem, and is a plant classified into the mallow family. Hibiscus cannabinus and hibiscus sabdariffa etc. under the scientific name are included, and further, red burdock, cucumber kenaf, western hemp, taykenaf, mesta, bimli, umbari and bombay hemp etc. are included under common names.
The jute in the present invention is a fiber obtained from jute hemp. This jute hemp shall include hemp and linden plants including jute (Chorus corpus capsularis L.), and hemp (Tunaso), Shimatsunaso and Morohaya.

  Furthermore, among the plant materials, plant materials obtained from kenaf are preferable, and it is particularly preferable to use kenaf fibers obtained from kenaf bast and / or kenaf core obtained from kenaf wood. Among these, in particular, when a kenaf core is used, it is lighter and can have a higher bending elastic modulus than when a kenaf fiber is used.

Moreover, although the shape of plant material is not specifically limited, A fibrous body and a granular material are mentioned. That is, for example, fibrous materials such as plant fibers (kenaf bast fibers) extracted from plant materials, and granular materials (such as kenaf core pulverized products) obtained by crushing and / or crushing plant materials. However, in the case of a fibrous body, the single fiber diameter exceeds 2 μm and is usually 10 μm or more.
Among these, when it is a fibrous body, the fiber length can be 10 mm or more. If the fiber length is 10 mm or more, it is easy to obtain higher strength (such as bending strength and bending elastic modulus) in a molded body using the obtained thermoplastic resin composition. The fiber length is preferably 10 to 150 mm, more preferably 20 to 100 mm, and particularly preferably 30 to 80 mm. Further, the fiber diameter is usually more than 2 μm and 1 mm or less. If the fiber diameter exceeds 2 μm and is 1 mm or less, particularly high strength can be obtained in the molded product. The fiber diameter is preferably 0.01 to 1 mm, more preferably 0.05 to 0.7 mm, and particularly preferably 0.07 to 0.5 mm. Furthermore, it is preferable that it is 1-10 dtex. Moreover, it is preferable to suppress the fiber of the form which remove | deviates from the said range to 10 mass% or less of the whole plant material. Thereby, the strength of the molded body obtained can be maintained high.
On the other hand, when using a granular material (including pulverized particles, plate chips, irregular crushed materials, etc.) as the plant material, the average particle size (average maximum length) is 7 mm or less (preferably 0.3 to 5 mm). , More preferably 0.5 to 3 mm, usually 0.1 mm or more).

  When the plant material is contained in the thermoplastic resin composition, the amount of the plant material to be used is not particularly limited. However, when the total of the plant material, the cellulose nanofiber and the thermoplastic resin is 100% by mass, the plant material is 30% by mass. % Or more (preferably 50% by mass or more, more preferably 60% by mass or more, and usually 90% by mass or less). Within this range, synergistically superior strength (particularly flexural strength and flexural modulus) can be obtained by including plant material and cellulose nanofibers.

The thermoplastic resin composition according to the present method can contain other components in addition to the cellulose nanofibers, the thermoplastic resin, and the plant material. As another component, the carbodiimide compound in the case of using the said polyester resin as a thermoplastic resin is mentioned.
Examples of the carbodiimide compound include dicyclohexylcarbodiimide, dicyclohexylcarbodiimide, diisopropylcarbodiimide, and 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride. These may use only 1 type and may use 2 or more types together.

  Although the usage-amount of carbodiimide is not specifically limited, 0.1-5 mass parts is preferable when the said polyester resin (especially polylactic acid) to be used is 100 mass parts. In this range, the hydrolysis-inhibiting action of the biodegradable resin due to the use of the carbodiimide compound can be obtained more effectively. Furthermore, the amount of the carbodiimide compound is more preferably 0.1 to 2 parts by mass, and particularly preferably 0.5 to 1.0 part by mass. In this range, it can be obtained particularly effectively in view of the hydrolysis-inhibiting action and cost of the carbodiimide compound.

In addition, in this method, other components other than cellulose nanofiber, thermoplastic resin, plant material, and carbodiimide can be blended. Furthermore, as other components, various antistatic agents, flame retardants, antibacterial agents, colorants and the like can be mixed. These may use only 1 type and may use 2 or more types together.
Further, the mixing of the above-mentioned other components and further other components may be performed together with (1) mixing of the cellulose nanofiber aqueous dispersion and the thermoplastic resin, and (2) cellulose nanofiber water. Other components may be mixed in the mixture of the dispersion and the thermoplastic resin, or (3) they may be mixed in other steps. Among these, the above (1) is preferable from the viewpoint of production efficiency.

[2] Manufacturing method of molded body The manufacturing method of the molded body of the present invention is characterized in that a molded body is obtained by extrusion molding or injection molding of the thermoplastic resin composition obtained by the manufacturing method of the present invention. Manufacturing method of a molded object.
The thermoplastic resin composition obtained by the method for producing a thermoplastic resin can be shaped by extrusion molding or injection molding. These moldings can be performed by connecting an extruder or an injection molding machine to a stirrer. Moreover, after cooling the obtained thermoplastic resin composition and chipping using a crusher etc., you may shape | mold by throwing this chip | tip into an extrusion molding machine or an injection molding machine.

  The shape, size, thickness and the like of the molded body obtained by this method are not particularly limited. Further, its use is not particularly limited. This molded body is used for, for example, interior materials, exterior materials, and structural materials such as automobiles, railway vehicles, ships, and airplanes. Among these, examples of the automobile article include an automobile interior material, an automotive instrument panel, and an automotive exterior material. Specifically, door base material, package tray, pillar garnish, switch base, quarter panel, armrest core material, automotive door trim, seat structure material, console box, automotive dashboard, various instrument panels, deck trim, Examples include bumpers, spoilers, and cowlings. Furthermore, for example, interior materials such as buildings and furniture, exterior materials, and structural materials may be mentioned. That is, a door cover material, a door structure material, a cover material of various furniture (desk, chair, shelf, bag, etc.), a structural material, etc. are mentioned. In addition, a package, a container (such as a tray), a protective member, a partition member, and the like can be given.

  The thermoplastic resin composition (the thermoplastic resin and the cellulose nanofibers are mixed by mixing the thermoplastic resin and the aqueous dispersion of cellulose nanofibers by the method for producing a thermoplastic resin composition described in [1] above. A thermoplastic resin composition that does not contain plant material), and then blends the fiber made of thermoplastic resin into a fiber shape by spinning the thermoplastic resin composition and the plant material. Etc.) and can be directly molded into a mat shape or a board shape to obtain a molded body.

Hereinafter, the present invention will be specifically described with reference to examples.
[1] Manufacture of thermoplastic resin composition and manufacture of molded body (test piece)
<Example 1>
270 g of a polylactic acid resin (manufactured by Toyota Motor Corporation, product name “U's S-12”), which is a thermoplastic resin, and 300 g of an aqueous dispersion of cellulose nanofibers (solid content concentration 10% by mass) are mixed with a stirrer ( After being put into the material supply chamber of M & F Technology Co., Ltd. (equipment shown in WO 2004-076044), the mixed material (polylactic acid resin and aqueous dispersion of cellulose nanofibers) was stirred and kneaded in the mixing chamber. . Then, the load (torque) applied to the rotating shaft on which the mixing blades were arranged increased, and when it began to decrease after reaching the maximum value, stirring was stopped (mixed for about 150 seconds). When stopped, the thermoplastic resin constituting the thermoplastic resin composition in the mixing chamber was in a semi-molten state. The obtained thermoplastic resin composition was discharged from a stirrer and allowed to cool to obtain a thermoplastic resin composition (block) containing 10% by mass of cellulose nanofibers.

  The obtained thermoplastic resin composition was crushed to about 5 mm square using a crusher to obtain a thermoplastic resin composition chip. The obtained thermoplastic resin composition chip was put into an injection molding machine (model “MD350S-IIIDP” manufactured by Ube Industries Co., Ltd.), and injection molded under conditions of a cylinder temperature of 190 ° C. and a mold temperature of 50 ° C. A plate-shaped test piece having a size of 4 mm, a width of 10 mm, and a length of 110 mm was obtained.

<Example 2>
The same procedure as in Example 1 was performed except that the blending amount of the polylactic acid resin was 240 g, the blending amount of the aqueous dispersion of cellulose nanofibers (solid content concentration: 10% by mass) was 600 g, and the mixing (stirring) time was 180 seconds. Thus, a thermoplastic resin composition (block) containing 20% by mass of cellulose nanofibers was obtained. Thereafter, a test piece was obtained in the same manner as in Example 1.

<Example 3>
120 g of polylactic acid resin (similar to Example 1), 800 g of an aqueous dispersion of cellulose nanofibers (similar to Example 1), and 200 g of kenaf core pulverized material (average particle size 1.0 mm) as a plant material After being put into the material supply chamber (same as in Example 1), the mixed material (polylactic acid resin, aqueous dispersion of cellulose nanofiber and kenaf core pulverized product) was stirred for 240 seconds in the mixing chamber as in Example 1. And kneaded to obtain a thermoplastic resin composition (lump) containing 20% by mass of cellulose nanofibers and 50% by mass of crushed kenaf core. Thereafter, a test piece was obtained in the same manner as in Example 1.

<Comparative Example 1>
Only a polylactic acid resin (same as in Example 1) was used, and a test piece was obtained by injection molding (however, the mold temperature was 40 ° C.) in the same manner as in Example 1.

<Comparative Example 2>
180 g of polylactic acid resin (same as in Example 1), without blending an aqueous dispersion of cellulose nanofibers, 420 g of kenaf core pulverized material (same as in Example 1), and a stirrer (same as in Example 1) After feeding into the supply chamber, the mixed material (polylactic acid resin and kenaf core pulverized product) is stirred and kneaded in the mixing chamber for 130 seconds in the same manner as in Example 1, and a thermoplastic resin in which 70% by mass of the kenaf core pulverized product is blended. A composition (lump) was obtained. Thereafter, a test piece was obtained in the same manner as in Example 1.

[2] Evaluation of molded body (test piece) (1) Characteristic evaluation of bending strength and flexural modulus Each test piece obtained in Examples 1 to 3 and Comparative Examples 1 to 2 (thickness 4 mm, width 10 mm, The bending strength and bending elastic modulus of the plate having a length of 110 mm were measured. In this measurement, while supporting each test piece at two fulcrums (curvature radius 5 mm) with a distance (L) between the fulcrums of 64 mm, the speed is 2 mm / min from the action point (curvature radius 5 mm) arranged at the center between the fulcrums. The bending strength and bending elastic modulus were calculated according to JIS K7171.

[3] Effects of Examples From the results of Examples, according to this method, dehydration of cellulose nanofibers and mixing with a thermoplastic resin can be simultaneously performed in an extremely short time. In particular, mixing cellulose nanofibers and a thermoplastic resin in one step is excellent in mass productivity. Moreover, the nonuniformity of the thermoplastic resin composition by visual observation is not recognized, and it turns out that the cellulose nanofiber is uniformly disperse | distributed in a thermoplastic resin also from the result of bending strength and a bending elastic modulus.

  Moreover, from the result of Table 1, compared with the test piece which consists only of the polylactic acid resin of the comparative example 1, the test piece which added the cellulose nanofiber of Example 1 has few compounding quantities of a cellulose nanofiber as 10 mass%. Nevertheless, it can be seen that the bending strength is improved by 12% and the bending elastic modulus by 21%.

  Similarly, when Comparative Example 2 is compared with Example 3, both the bending strength and the elastic modulus are improved when cellulose nanofibers are used in combination, compared with the case where the kenaf core pulverized product is added alone (Comparative Example 2). You can see that That is, it can be seen that Example 3 is improved as compared with Comparative Example 2 with a bending strength of 22% and a bending elastic modulus of 6%. It can also be seen that this effect is superior in bending strength.

Further, when Example 1 and Example 2 are compared, the blending amount of cellulose nanofiber is 20% by mass, so that the bending strength is 27% and the flexural modulus is 20% with respect to Example 1. Compared to 1, a significant strength improvement effect was observed. In particular, when Comparative Example 1 is compared with Example 2, it can be seen that the bending strength is extremely effectively improved to 43%.
From the results of Examples 1 to 3 and Comparative Examples 1 and 2, by adding cellulose nanofibers, the brittleness is improved as compared to the conventional case, and a molded product having a hard and moderate flexibility can be obtained. I understand that I can do it.

  The method for producing a thermoplastic resin composition and the method for producing a molded product of the present invention are widely used in the fields related to automobiles and fields related to construction. It is particularly suitable for interior materials, exterior materials, and structural materials for automobiles, railway vehicles, ships, airplanes, etc., and among them, it is suitable for automobile interior materials, automotive instrument panels, automotive exterior materials, etc. is there. Specifically, door base material, package tray, pillar garnish, switch base, quarter panel, armrest core material, automotive door trim, seat structure material, console box, automotive dashboard, various instrument panels, deck trim, Examples include bumpers, spoilers, and cowlings. Furthermore, it is also suitable for interior materials, exterior materials and structural materials such as buildings and furniture. Specifically, door cover materials, door structure materials, cover materials for various furniture (desks, chairs, shelves, bags, etc.), structural materials, and the like can be given. In addition, it is also suitable as a package, a container (such as a tray), a protective member, and a partition member.

It is a typical sectional view showing an example of an agitator. It is a typical side view which shows an example of the mixing blade | wing arrange | positioned by the stirrer.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10; Stirrer, 11; Mixing chamber, 12; Material supply chamber, 13; Rotating shaft, 14; Spiral blade, 15 and 15a-15f;

Claims (5)

A method for producing a thermoplastic resin composition in which an aqueous dispersion of cellulose nanofibers and a thermoplastic resin are mixed with a stirrer to obtain a thermoplastic resin composition ,
The stirrer includes a mixing chamber for performing the mixing,
A method for producing a thermoplastic resin composition, comprising vaporizing water contained in the aqueous dispersion by the mixing and pressurizing the mixing chamber.   The method for producing a thermoplastic resin composition according to claim 1, wherein the thermoplastic resin is a biodegradable resin. The manufacturing method of the thermoplastic resin composition of Claim 1 or 2 which mixes a plant material with the said stirrer further with the said aqueous dispersion of the cellulose nanofiber and the said thermoplastic resin. The method for producing a thermoplastic resin composition according to claim 3 , wherein the plant material is kenaf core. A method for producing a molded body, characterized in that a molded body is obtained by extrusion molding or injection molding the thermoplastic resin composition obtained by the manufacturing method according to any one of claims 1 to 4 .

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