WO2009116501A1

WO2009116501A1 - Process for production of thermoplastic resin composition, and process for production of thermoplastic resin molded article

Info

Publication number: WO2009116501A1
Application number: PCT/JP2009/055083
Authority: WO
Inventors: 正典羽柴
Original assignee: トヨタ紡織株式会社
Priority date: 2008-03-21
Filing date: 2009-03-16
Publication date: 2009-09-24
Also published as: JP2009227806A

Abstract

Disclosed is a process for producing a thermoplastic resin composition which has excellent injection molding performance in spite of a fact that the composition contains 50 to 95% by mass of a plant-derived material. Also disclosed is a process for producing a molded article by using a thermoplastic resin composition. The process for producing the composition involves a mixing step of mixing a plant-derived material (e.g., a kenaf fiber, a kenaf core) with a thermoplastic resin (e.g., polyprolylene) in a mixing/kneading apparatus. In the mixing step, an acid-modified thermoplastic resin (e.g., polypropylene　modified with maleic anhydride) is used in an amount of 0.5 to 30% by mass relative to the total amount (100% by mass) of the thermoplastic resin components. The process for producing the molded article involves a molding step of injection-molding the thermoplastic resin composition produced by the aforementioned process to form the molded article.

Description

Method for producing thermoplastic resin composition and method for producing thermoplastic resin molded article

The present invention relates to a method for producing a thermoplastic resin composition and a method for producing a thermoplastic resin molded article. More specifically, the present invention relates to a method for producing a thermoplastic resin composition containing as much as 50 to 95% by mass of a plant material and a method for producing a thermoplastic resin molded article.

In recent years, plant materials such as kenaf that grow rapidly and have a large amount of carbon dioxide absorption are attracting attention from the viewpoints of reducing carbon dioxide emissions, fixing carbon dioxide, and the like, and are expected to be used in combination with resins.
However, it is particularly difficult to mix a large amount of plant material with the resin and to mold the resulting composite material. This is considered to be because it is difficult to give the composite material sufficient fluidity equivalent to the conventional resin. The following Patent Documents 1 and 2 are known as techniques for handling composite materials containing a large amount of plant material.

JP 2005-105245 A JP 2000-211981

In the above-mentioned Patent Document 1, when the content of kenaf fiber exceeds 50% by mass, the fluidity of the resin composition is remarkably lowered, so that there is a problem that a satisfactory product shape and product form cannot be obtained in injection molding. It has been shown to occur. On the other hand, in Patent Document 2, when only rosin or plasticizer is not added to the resin and only the plant fiber is blended, the plant fiber is difficult to be uniformly dispersed, and the affinity between the resin and the plant fiber is poor. It is shown that only materials with poor strength and the like, lack of uniformity of quality, and poor practicality can be obtained.
That is, in any document, it is shown that it is difficult to obtain an injection-moldable thermoplastic resin containing a large amount of plant material exceeding 50% by mass.

The present invention has been made in view of the above, and uses a method for producing a thermoplastic resin composition excellent in injection moldability while containing a large amount of plant material in an amount of 50 to 95% by mass, and a thermoplastic resin composition. An object of the present invention is to provide a method for producing a molded article.

That is, the present invention is as follows.
(1) A thermoplastic resin composition comprising a plant material and a thermoplastic resin, and the plant material and the thermoplastic resin in a total amount of 100% by mass, the plant material being contained in an amount of 50 to 95% by mass. A method for manufacturing a product,
A mixing step of mixing the plant material and the thermoplastic resin with a mixing and melting apparatus;
The method for producing a thermoplastic resin composition, wherein in the mixing step, 1 to 30% by mass of an acid-modified thermoplastic resin is used when the total amount of the thermoplastic resin is 100% by mass.
(2) The said vegetable material is a manufacturing method of the thermoplastic resin composition as described in said (1) containing vegetable fiber.
(3) The method for producing a thermoplastic resin composition according to (2), wherein the vegetable fiber has an average fiber length of 0.5 to 20 mm.
(4) The method for producing a thermoplastic resin composition according to any one of (1) to (3), wherein the plant material is kenaf.
(5) The method for producing a thermoplastic resin composition according to any one of (1) to (4), wherein the acid-modified thermoplastic resin has an acid value of 5 or more.
(6) The method for producing a thermoplastic resin composition according to any one of (1) to (5), wherein the acid-modified thermoplastic resin has a weight average molecular weight of 10,000 to 200,000.
(7) The mixing and melting apparatus includes a mixing chamber for performing the mixing and a mixing blade disposed in the mixing chamber,
The thermoplastic resin according to any one of (1) to (6), wherein the mixing step mixes the thermoplastic resin melted by rotation of the mixing blade in the mixing chamber and the plant material. A method for producing a resin composition.
(8) The thermoplastic according to any one of (1) to (7), further comprising a pelletizing step after the mixing step, wherein the mixture obtained in the mixing step is pressed and consolidated without heating. A method for producing a resin composition.
(9) A molding step of obtaining a molded body by injection molding the thermoplastic resin composition obtained by the method for producing a thermoplastic resin composition according to any one of (1) to (8) above is provided. A method for producing a thermoplastic resin molded article.

According to the method for producing a thermoplastic resin composition of the present invention, an excellent injection moldability can be obtained as compared with the prior art while containing a large amount of plant material at 50 to 95% by mass. In particular, a high fluidity can be obtained, and a thermoplastic resin composition that can be molded at a low injection filling pressure can be obtained. Further, this makes it possible to form into a larger shape and a finer shape with excellent formability. Furthermore, excellent mechanical properties can be obtained with a molded body using this thermoplastic resin composition.
In the case where the plant material contains plant fibers, the fluidity is further improved and high formability can be obtained. In addition, excellent mechanical properties can be obtained with a molded article obtained using this thermoplastic resin composition.
When the average fiber length of the vegetable fiber is 0.5 to 20 mm, particularly high fluidity can be obtained, and further excellent formability can be obtained. In addition, excellent mechanical properties can be obtained with a molded article obtained using this thermoplastic resin composition.
When the plant material is kenaf, kenaf is an extremely fast growing annual grass and has an excellent carbon dioxide absorbability, so that it can contribute to the reduction of the amount of carbon dioxide in the atmosphere and the effective use of forest resources.
When the acid value of the acid-modified thermoplastic resin is 5 or more, particularly high fluidity can be obtained, and further excellent formability can be obtained. In addition, excellent mechanical properties can be obtained with a molded article obtained using this thermoplastic resin composition.
When the weight average molecular weight of the acid-modified thermoplastic resin is 10,000 to 200,000, particularly high fluidity can be obtained, and further excellent formability can be obtained. In addition, excellent mechanical properties can be obtained with a molded article obtained using this thermoplastic resin composition.
When mixing the thermoplastic resin melted by the rotation of the mixing blade and the plant material in the mixing chamber, the mixing can be performed in a particularly short time, and the thermoplastic resin is not required from the outside. A composition can be produced. Furthermore, since heating is not required and a separate heating means is not required and mixing can be performed in a short time, a thermoplastic resin composition can be produced at low cost.
When equipped with a pelletizing step that obtains pellets by pressing and solidifying the mixture obtained in the mixing step without heating, it is possible to suppress thermal degradation of the thermoplastic resin to perform pelletization without heating, and to obtain a thermoplastic resin molding The mechanical properties of the body can be improved.
According to the method for producing a thermoplastic resin molded article of the present invention, a thermoplastic resin composition can be molded by injection molding despite containing a large amount of plant material. Furthermore, these moldings can be performed at a low filling pressure, and in addition, formability (moldability) is also excellent. For this reason, the shaping | molding excellent in productivity can be performed. Moreover, in the obtained molded object, a high mechanical characteristic is acquired.

It is a graph which shows the correlation with the ratio of the acid-modified thermoplastic resin in a thermoplastic resin, injection filling pressure, and bending strength. It is a graph which shows the correlation with the ratio of the vegetable fiber in plant material, injection filling pressure, and bending strength. It is an example of the manufacturing method of a thermoplastic resin composition, Comprising: It is typical explanatory drawing explaining the case where a pelletizing process is provided in addition to a mixing process. It is typical sectional drawing which shows an example of a mixing-melting apparatus. It is a typical side view which shows an example of the mixing blade | wing arrange | positioned by the mixing-melting apparatus. It is a typical perspective view which shows an example of the principal part of a roller disc die type molding machine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1; Stirrer, 3; Mixing chamber, 5; Rotating shaft, 10 and 10a-10f; Mixing blade, 12; Spiral blade, 13; Material supply chamber, 500; Roller disk die type molding machine (pelletizing apparatus), 50; Roller disk die type molding part (pelletizing part), 51; Disc die, 511; Through hole, 512; Main rotation shaft insertion hole, 52; Press roller, 521; Concavity and convexity, 53; Main rotation shaft, 54; Press roller fixed shaft 55; cutting blade.

Hereinafter, the present invention will be described in detail.
[1] Method for producing thermoplastic resin composition The method for producing the thermoplastic resin composition of the present invention comprises:
Production of a thermoplastic resin composition comprising a plant material and a thermoplastic resin, wherein the plant material and the thermoplastic resin are 100% by mass, and the plant material is contained in an amount of 50 to 95% by mass. A method,
A mixing step of mixing the plant material and the thermoplastic resin with a mixing and melting apparatus;
The mixing step is characterized in that 1 to 30% by mass of an acid-modified thermoplastic resin is used when the total thermoplastic resin is 100% by mass.

The “mixing step” is a step of mixing the plant material and the thermoplastic resin with a stirrer.
The “plant material” is a material derived from a plant. These plant materials include kenaf, jute hemp, manila hemp, sisal hemp, husk, cocoon, cocoon, banana, pineapple, coconut palm, corn, sugar cane, bagasse, palm, papyrus, cocoon, esparto, sabaigrass, wheat, rice, bamboo And 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. Of these, kenaf is preferred. This is because kenaf is an annual plant that grows very fast and has excellent carbon dioxide absorptivity, which contributes to reducing the amount of carbon dioxide in the atmosphere and effectively using forest resources.
Moreover, the 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 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.

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. in scientific names are included, and further, red, heba, cubane kenaf, western hemp, taikenaf, mesta, bimli, ambari, and bombay are known as 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.

The shape of the plant material (plant material before mixing) is not particularly limited, and is fibrous, powdery (including granular and spherical), chip (including plate and flakes), and irregular shape ( And the like). Although these may use only 1 type and may use 2 or more types together, it is preferable that vegetable fiber is contained as said plant material especially. That is, in this method, only plant fiber is used as the plant material, or a combination of plant fiber and non-fiber plant material (hereinafter simply referred to as “non-fiber plant material”), Is preferred.

In this method, although the reason is not clear, when the vegetable fiber and the acid-modified thermoplastic resin are used in combination, the fluidity of the resulting thermoplastic resin composition is significantly improved, The fluidity of the thermoplastic resin composition can be further improved by increasing the proportion of vegetable fibers in the plant material (see FIG. 2). That is, by using a vegetable fiber and an acid-modified thermoplastic resin in combination, it is possible to obtain a thermoplastic resin molded article having excellent mechanical properties, as well as high formability, and to a finer shape. And larger moldings can be formed. Moreover, such a molded body can be manufactured at a lower cost.

The plant fiber is a fiber taken out from a plant body and has a ratio L / t of the fiber diameter t to the fiber length L of 5.0 to 20,000. Those outside this range are non-fibrous plant materials in the present invention. In the vegetable fiber, the fiber length L is usually 0.5 to 300 mm, and the fiber diameter t is usually 0.01 to 1 mm. This fiber length is a value (L) measured on a measuring scale by stretching a single plant fiber straight without stretching, as in the direct method in JIS L1015. On the other hand, a fiber diameter is the value (t) which measured the fiber diameter in the center of the fiber length direction using the optical microscope about the vegetable fiber which measured fiber length.

Furthermore, the average fiber length and the average fiber diameter of the vegetable fiber are not particularly limited, but the average fiber length is preferably 20 mm or less. By using a vegetable fiber having an average fiber length of 20 mm or less, the above-described effect by using the vegetable fiber can be better obtained. The average fiber length is more preferably 1 to 15 mm, further preferably 2 to 10 mm, and particularly preferably 3 to 7 mm. This average fiber length is determined according to JIS L1015 by taking out single fibers one at a time by the direct method, stretching straight without stretching, and measuring the fiber length on a measuring scale. It is the measured average value.
On the other hand, the average fiber diameter is preferably 0.2 mm or less. By using vegetable fibers having an average fiber diameter of 0.2 mm or less, the above-mentioned effect by using vegetable fibers can be obtained better. The average fiber diameter is more preferably 0.01 to 0.15 mm, and particularly preferably 0.01 to 0.1 mm. 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, when using the above-mentioned non-fibrous plant material, that is, for example, when using powdery, chip-like and amorphous plant materials, the size of the non-fibrous plant material is not particularly limited. The maximum length (maximum particle size in the case of granules) is 20 mm or less (usually 0.1 mm or more, more preferably 0.3 to 20 mm, even more preferably 0.3 to 15 mm, particularly 1 to 10 mm). Is preferred.
In the thermoplastic resin composition obtained by this method, the shape and size of the plant material before mixing may or may not be maintained as it is in the thermoplastic resin composition. The case where it is not maintained includes a case where it is further finely pulverized during mixing and contained in the thermoplastic resin composition.

The blending ratio of the vegetable fiber to the whole plant material is not particularly limited, but when the whole plant material is 100% by mass, the plant fiber is 5% by mass or more (may be 100% by mass). It is preferable. In this range, the fluidity of the thermoplastic resin composition can be effectively improved while obtaining the effect of improving the mechanical properties of the thermoplastic resin molded article due to the inclusion of vegetable fibers. As described above, this ratio is 100% by mass when all of the plant material is plant fiber, but when the plant fiber and the non-fiber plant material are used in combination, the ratio is 5 to 5%. It is preferable to set it as 99 mass%. In this range, it is particularly easy to obtain a fluidity improving effect by blending vegetable fibers. Further, this ratio is more preferably 10 to 90% by mass, further preferably 20 to 80% by mass, and particularly preferably 25 to 75% by mass.

In addition, when kenaf is used as the plant material, kenaf core can be used as the non-fibrous plant material. Kenaf consists of an outer layer part called bast and a core part called core. Among these, bast is highly useful because it has tough fibers, whereas the core is the whole kenaf. Although it occupies as much as 60% by volume, it cannot be made into a vegetable fiber. Furthermore, since the apparent specific gravity is small and bulky, handling is poor, kneading with the resin is difficult, and the core is often discarded or made into fuel. However, according to this method, the fluidity of the thermoplastic resin composition can be sufficiently enhanced while using kenaf core as a plant material.

The plant material contained in the thermoplastic resin composition obtained by this method is 50 to 95% by mass. This content is usually the same as the blending amount of the plant material blended during production. That is, when the total of the plant material and the thermoplastic resin is 100% by mass, 50 to 95% by mass of the plant material is blended. The blending amount is preferably 50 to 90% by mass, more preferably 52 to 87% by mass, further preferably 54 to 85% by mass, particularly preferably 56 to 83% by mass, and particularly preferably 58 to 80% by mass.

The “thermoplastic resin” is a resin mixed with the plant material in the mixing step. The thermoplastic resin used in this mixing step (100% by mass of the entire thermoplastic resin) contains 1 to 30% by mass of an acid-modified thermoplastic resin that is an acid-modified thermoplastic resin. In this method, by using this acid-modified thermoplastic resin, the mechanical properties of a thermoplastic resin molded article using the thermoplastic resin composition according to this method can be improved.
In the present invention, hereinafter, among the thermoplastic resins, other thermoplastic resins excluding the acid-modified thermoplastic resins are also referred to as “non-acid-modified thermoplastic resins”.

The “acid-modified thermoplastic resin” is a thermoplastic resin having an acid group. Examples of the acid-modified thermoplastic resin include those obtained by introducing an acid group into the following thermoplastic resin (hereinafter, a resin in which no acid group is introduced is also referred to as “base resin”).
Namely, polyolefin, polyester resin, polystyrene, acrylic resin (resin obtained using methacrylate and / or acrylate), polyamide resin, polycarbonate resin, polyacetal resin, ABS resin, olefin elastomer resin, styrene elastomer resin, nitrile Mixed resin of rubber (NBR) and olefin resin (NBR-added olefin resin), mixed resin of ethylene-propylene-diene rubber (EPDM) and NBR-added olefin resin, styrene-butadiene-styrene block copolymer (SBS) Examples thereof include a mixed resin of a hydrogenated styrene-butadiene-styrene block copolymer (SBBS) and a styrene-ethylene-butylene-styrene block copolymer (SEBS). These may use only 1 type and may use 2 or more types together.

Among the above base resins, examples of the polyolefin include polypropylene, polyethylene, and ethylene / propylene random copolymer. Examples of the polyester resin include aliphatic polyester resins such as polylactic acid, polycaprolactone, and polybutylene succinate, and aromatic polyester resins such as polyethylene terephthalate, polytrimethylene terephthalate, and polybutylene terephthalate.

The type of the acid group is not particularly limited, but is usually a carboxylic acid anhydride residue (—CO—O—OC—) and / or a carboxylic acid residue (—COOH). This acid group may be introduced at the copolymerization stage or may be grafted. The acid group may be introduced by any compound, and examples of the compound include maleic anhydride, itaconic anhydride, succinic anhydride, glutaric anhydride, adipic anhydride, maleic acid, itaconic acid. , Fumaric acid, acrylic acid, and methacrylic acid. These may use only 1 type and may use 2 or more types together. Of these, maleic anhydride and itaconic anhydride are preferred, and maleic anhydride is particularly preferred.

Although the amount of acid groups introduced into the acid-modified thermoplastic resin is not particularly limited, the acid value is preferably 5 or more. This is because by using such an acid-modified thermoplastic resin, a high addition effect can be obtained while suppressing the addition amount of the acid-modified thermoplastic resin. The acid value is more preferably 10 to 80, further preferably 15 to 70, and particularly preferably 20 to 60. This acid value is according to JIS K0070.

Furthermore, the molecular weight of the acid-modified thermoplastic resin is not particularly limited, but is preferably 10,000 to 200,000 in terms of weight average molecular weight. That is, an acid-modified thermoplastic resin having a relatively small molecular weight is preferable. By using such an acid-modified thermoplastic resin, it is possible to obtain a high addition effect while suppressing property changes to the entire thermoplastic resin composition due to the addition of the acid-modified thermoplastic resin. Furthermore, it is considered that the fluidity of the resulting thermoplastic resin composition can be improved by using an acid-modified thermoplastic resin in this range. The weight average molecular weight is more preferably 15,000 to 150,000, still more preferably 25,000 to 120,000, and particularly preferably 35,000 to 100,000. The weight average molecular weight is based on the GPC method.

On the other hand, the resin other than the acid-modified thermoplastic resin constituting the thermoplastic resin (that is, non-acid-modified thermoplastic resin) is not particularly limited except that it is thermoplastic. As this non-acid-modified thermoplastic resin (type of non-acid-modified thermoplastic resin), polyolefin, polyester resin, polystyrene, acrylic resin (resin obtained using methacrylate and / or acrylate, etc.), polyamide resin, polycarbonate resin , Polyacetal resins and ABS resins. Among these, as the polyolefin, polypropylene, polyethylene, ethylene / propylene copolymer (ethylene / propylene block copolymer, ethylene / propylene random copolymer) and the like can be mentioned. Examples of the polyester resin include aliphatic polyester resins such as polylactic acid, polycaprolactone, and polybutylene succinate, and aromatic polyester resins such as polyethylene terephthalate, polytrimethylene terephthalate, and polybutylene terephthalate. These non-acid-modified thermoplastic resins may be used alone or in combination of two or more.

The base resin constituting the acid-modified thermoplastic resin and the non-acid-modified thermoplastic resin may be the same (same type) or different (even different types), but they are the same. It is preferable that both are polyolefins. Polyolefin is easy to handle and can improve productivity. Further, high flexibility and excellent moldability can be obtained. In particular, since the resin is originally excellent in injection moldability, higher fluidity can be obtained by applying this method compared to the case of using other resins. Among polyolefins, polypropylene, polyethylene, ethylene / propylene copolymer, and mixed resin (alloy) of polypropylene and polyethylene are preferable. Furthermore, as the non-acid-modified thermoplastic resin, polypropylene or the above mixed resin is particularly preferable, and as the base resin constituting the acid-modified thermoplastic resin, polypropylene is particularly preferable.
Therefore, as the non-acid-modified thermoplastic resin, polypropylene or the above mixed resin is particularly preferable, and as the acid-modified thermoplastic resin, maleic anhydride-modified polypropylene is particularly preferable.

Further, when the thermoplastic resin is 100% by mass as a whole, the ratio of the acid-modified thermoplastic resin is 1 to 30% by mass. If the blending amount is within this range, it is a matter of course that the mechanical properties of the resulting molded body (thermoplastic resin molded body) can be improved by the combined use with the non-acid-modified thermoplastic resin. The fluidity at the time can be dramatically improved. In addition, fluidity can be further improved by using plant fiber as the plant material. The amount is preferably 1 to 27% by mass, more preferably 1 to 22% by mass, and still more preferably 1.5 to 17% by mass.

The above-mentioned “mixing and melting apparatus” is an apparatus that melts and mixes a thermoplastic resin and a vegetable material, and excludes an extrusion type apparatus. The type of the mixing and melting apparatus is not particularly limited, but the following mixing and melting apparatus is particularly preferable. When this mixing and melting apparatus is used, in addition to the blending of the acid-modified thermoplastic resin and the blending of the vegetable fiber, higher fluidity can be obtained.

This mixing and melting apparatus (hereinafter, FIG. 3 and FIG. 4 (FIG. 4 is cited from the pamphlet of International Publication No. 04/076044 obtained from the Patent Electronic Library of the Patent Office) and FIG. 5 (FIG. 5 is the patent office patent). As the reference}, reference is made to the International Publication No. 04/076044 pamphlet obtained from the electronic library), and the mixing and melting apparatus 1 described in the International Publication No. 04/076044 pamphlet is preferable. That is, the mixing and melting apparatus 1 includes a material supply chamber 13, a mixing chamber 3 connected to the material supply chamber 13, and a rotation provided rotatably through the material supply chamber 13 and the mixing chamber 3. A spiral shape that is arranged on the shaft 5 and the rotating shaft 5 in the material supply chamber 13 and that supplies the mixed material (plant material and thermoplastic resin) supplied to the material supply chamber 13 to the mixing chamber 3. A mixing and melting apparatus including blades 12 and mixing blades 10a to 10f disposed on the rotating shaft 5 in the mixing chamber 3 and mixing the mixed material is preferable.

By using the mixing and melting apparatus, the plant material and the thermoplastic resin are put into the mixing and melting apparatus 1 (material supply chamber 13), and the mixing blades 10a to 10f of the mixing and melting apparatus 1 are rotated, whereby the plant material and the heat Both the plastic resin is struck and pushed so as to be pressed against the inner wall of the mixing chamber 3, and the thermoplastic resin is softened and melted in a short time by the energy (heat amount) that the materials collide with each other. And kneaded. Moreover, the fluidity which can be injection-molded is expressed in the obtained mixture (thermoplastic resin composition before pelletization).

The mixing blades 10a to 10f are arranged on the rotary shaft 5 at an attachment angle so as to face each other in the axial direction at a constant angular interval in the circumferential direction of the rotary shaft 5 and to narrow the opposing interval in the rotational direction. The mixing blades 10a to 10f are provided with at least two mixing blades (10a to 10f), and the angle of attachment of the mixing blades 10a to 10f with respect to the rotary shaft 5 is the base of the mixing blades 10a to 10f attached to the rotary shaft 5 To the radially outer tip, and the mixing blades 10a to 10f preferably have a rectangular plate shape.
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 and thermal deterioration of the thermoplastic resin can be suppressed (and further prevented).

Various conditions in the above “mixing” are not particularly limited. For example, the temperature during mixing is not particularly limited, but the temperature of the outer wall of the mixing chamber is 200 ° C. or lower (more preferably 150 ° C. or lower, more preferably 120 ° C. or lower). It is preferable to control, and it is preferable to control to 50 degreeC or more (more preferably 60 degreeC or more, still more preferably 80 degreeC or more). The temperature is preferably reached within 10 minutes (more preferably within 5 minutes). By making the temperature high in a short time, the water can be rapidly evaporated and the above mixing can be performed, and the deterioration of the thermoplastic resin can be more effectively suppressed. Further, the temperature range is preferably within 15 minutes (more preferably within 10 minutes).
The temperature is preferably controlled by controlling the rotation speed of the mixing blade of the mixing and melting apparatus. More specifically, it is preferable to control the rotational speed at the tip of the mixing blade to be 5 m / sec to 50 m / sec. By controlling within this range, it is possible to more strongly (more uniformly) mix with the plant material while efficiently softening and melting the thermoplastic resin.

Furthermore, the end point in 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. As a result, the plant material and the thermoplastic resin can be mixed with each other with good 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. Thereby, the plant material and the thermoplastic resin can be mixed with each other with good dispersibility, and the mixture (the thermoplastic resin composition before pelletization) can be taken out from the inside of the mixing chamber at a temperature of 160 ° C. or higher. It can prevent more reliably that a thermoplastic resin composition adheres and remains in a room | chamber interior.

In the production method of the present invention, other components can be blended in addition to the plant material and the thermoplastic resin. As another component, the carbodiimide compound in the case of using the said polyester resin as a thermoplastic resin is mentioned. In addition, various antistatic agents, flame retardants, antibacterial agents, coloring agents, and the like can be blended. These may use only 1 type and may use 2 or more types together. These other components may be blended in any step, but are usually blended in the mixing step.

Further, in the method for producing a thermoplastic resin composition of the present invention, other steps can be provided in addition to the mixing step. As another process, the process (pelletization process) of pelletizing the thermoplastic resin composition obtained at the said mixing process is mentioned (refer FIG. 3). The thermoplastic resin composition of the present invention can then be injection-molded, but in this case, it is preferable that the thermoplastic resin composition is pelletized.

This pelletization may be done in any way. That is, for example, when using an apparatus in which the melt mixing apparatus and a pelletizing apparatus that can be pelletized (subdivided) before the obtained thermoplastic resin composition is removed from heat are integrally used, Mixing and pelletization can be performed continuously to obtain pellets. In addition, when using an apparatus that does not have a pelletizing apparatus as described above, since a bulk thermoplastic resin composition is usually obtained from a mixing and melting apparatus, the bulk thermoplastic resin composition is pelleted. Pellets can be obtained.

In the latter method (when a bulk thermoplastic resin composition is obtained from a mixing and melting apparatus), the mixture (thermoplastic resin composition before being pelletized) obtained in the mixing step is heated after the mixing step. It is preferable to provide a pelletizing step in which pellets are obtained by pressing and compacting (see FIG. 3). In this way, by pressing and solidifying without heating, for example, the thermoplastic resin composition obtained in the mixing step is melted again and pelletized using a general method such as a twin screw extruder. Compared with the case, since the heat history to a thermoplastic resin composition can be reduced, the mechanical characteristic of the molded object obtained can be maintained higher.

Any device and means may be used in the pelletizing step in which the pellets are pressed and consolidated without heating, and various compression molding methods are particularly preferable. Examples of the compression molding method include a roller molding method and an extruder molding method. The roller-type molding method is a method using a roller-type molding machine, in which a mixture is pressed into a die by a roller rotated in contact with the die, and then extruded from the die and molded. 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) having different die shapes. On the other hand, the extruder type molding method is a method using an extruder type molding machine. After the mixture is pressed into the die by the rotation of the screw auger, the mixture is extruded from the die and molded. Among these compression molding methods, a method using a roller disk die molding method is particularly preferable. The roller disk die type molding machine used in this compression molding method is particularly suitable because of its high compression efficiency.

Furthermore, in this method, it is particularly preferable to pelletize by using the following specific roller disk die molding machine 500 (FIG. 3 and main parts are illustrated in FIG. 6). That is, a disk die 51 having a plurality of through holes 511, a press roller 52 that rolls on the disk die 51 and pushes an uncompressed material (mixture) into the through hole 511, and the press roller 52 The disk die 51 has a main rotation shaft insertion hole 512 that is penetrated in the same direction as the through hole 511, and the main rotation shaft 53 is the main rotation shaft 53. The press roller fixing shaft 54 is inserted through the insertion hole 512 and perpendicular to the main rotation shaft 53, and the press roller 52 is rotatably supported by the press roller fixing shaft 54 so as to rotate the main rotation. A roller disk die molding machine (pelletizing apparatus) 500 having a roller disk die molding unit 50 that is rolled on the surface of the disk die 51 as the shaft 53 rotates.
In this roller disk die type molding machine 500, in addition to the above configuration, it is preferable that the press roller 52 further has irregularities 521 on the surface. Further, it is preferable to include a cutting blade 55 that is rotated in accordance with the rotation of the main rotating shaft 53.

In the roller disk die type molding machine 500, for example, in FIG. 6, the mixture introduced from above the main rotating shaft 53 is caught by the surface irregularities 521 provided in the press roller 52 and pushed into the through holes 511, and the disk die 51 Extruded from the back side. The extruded string-like mixture is cut into an appropriate length by the cutting blade 55, pelletized, dropped down and collected.
The shape and size of the pelletized thermoplastic resin composition are not particularly limited, but it is preferably a columnar shape (other shapes may be used but a cylindrical shape is preferable). The maximum length is preferably 1 mm or more (usually 20 mm or less), more preferably 1 to 10 mm, and particularly preferably 2 to 7 mm.

In this method, other steps can be provided in addition to the mixing step and the pellet step. As another process, the process of preparing a raw material pellet by pressing and solidifying the plant material used before a mixing process is mentioned.
That is, a raw material pellet manufacturing step of pressing and solidifying plant material to obtain a raw material pellet;
A mixing step of mixing raw material pellets and the thermoplastic resin (including 1 to 30% by mass of an acid-modified thermoplastic resin) with a melt mixing device;
It can be set as the manufacturing method of a thermoplastic resin composition provided with the pelletization process which presses and solidifies the mixture obtained at the said mixing process, and obtains a pellet in this order.
In the raw material pellet manufacturing process, the roller disk die molding machine 500 can be used as in the pelletizing process.
By providing the raw material pellet manufacturing process in this way, the specific gravity difference between the plant material and the thermoplastic resin can be reduced, workability can be improved, uneven distribution of the material during mixing can be suppressed, and the plant material and A thermoplastic resin composition in which the thermoplastic resin is uniformly dispersed can be obtained. Furthermore, the molded body obtained has a high mechanical strength.

[2] Method for Producing Molded Body The method for producing the molded body of the present invention is a thermoplastic resin composition (a pelletized thermoplastic resin composition) obtained by the method for producing a thermoplastic resin composition of the present invention. And a molding step of obtaining a molded body by injection molding.
The thermoplastic resin composition exhibits excellent fluidity while containing a large amount of plant material as described above. For this reason, as a result of shortening the metering time (such as the metering time in the injection molding machine) at the time of molding and the injection time, the molding cycle can be shortened and the molding efficiency can be improved. Various molding conditions and the apparatus to be used in the injection molding are not particularly limited, and it is preferable to use an appropriate one depending on the target molded body and properties, the type of thermoplastic resin used, and the like.

The shape, size, thickness and the like of the molded body obtained by the production method of the present invention are not particularly limited. Further, its use is not particularly limited. This molded body is used, for example, as an interior material, an exterior material, a structural material, or the like for an automobile, a railway vehicle, a ship, an airplane, or the like. Among these, examples of the automobile article include an automobile interior material, an automobile instrument panel, and an automobile exterior material. Specifically, door base material, package tray, pillar garnish, switch base, quarter panel, armrest core material, automotive door trim, seat structure material, seat backboard, ceiling material, console box, automotive dashboard, various types Instrument panel, deck trim, bumper, spoiler and cowling. 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.

Hereinafter, the present invention will be specifically described with reference to examples.
[1] Production of thermoplastic resin composition (1) Examples 1 to 15 and Comparative Examples 3 to 4
The following plant materials (kenaf fibers A to D, kenaf core), non-acid-modified thermoplastic resin (PP; polypropylene), and acid-modified thermoplastic resin (acid-modified PP; maleic anhydride-modified polypropylene) are shown in Table 1. Are used in the combinations and blending amounts shown in (4) to (4) and are introduced into the material supply chamber (13 in FIG. 4) of the mixing and melting apparatus 1 (equipment shown in WO2004-076044 by M & F Technology Co., Ltd.) 700 g in total with the thermoplastic resin) and then mixed in a mixing chamber (capacity 5 L, 3 in FIG. 4). During this mixing, the mixing blades (10 in FIG. 3 and 10a to 10f in FIG. 5) were rotated at a rotational speed of 2000 rpm. Then, the load (torque) applied to the mixing blade increases, reaches the maximum value (exceeds 100%) and stops mixing after 6 seconds, and the resulting mixture (thermoplastic resin before pelletization) is obtained. The composition was discharged from the mixing and melting apparatus.

After that, the obtained mixture was crushed to about 5.0 mm using a crusher (manufactured by Horai Co., Ltd., model “Z10-420”), and then a roller disk die molding machine 500 {manufactured by Kikukawa Iron Works, Inc. “KP280”, through-hole diameter (511 in FIG. 6) of 4.2 mm} is fed at a feeder frequency of 20 Hz, and at a pellet production rate of about 30 kg per hour, each mixture is a circle having a diameter of about 4 mm and a length of about 5 mm. Columnar pellets were obtained. Thereafter, the obtained pellets were dried in an oven at 100 ° C. for 24 hours to obtain thermoplastic resin compositions of Examples 1 to 15 and Comparative Examples 3 to 4.
In addition, each plant material is put into a roller disk die type molding machine {manufactured by Kikukawa Iron Works Co., Ltd., type "KP280", through-hole diameter 4.2 mm}, and is formed into a cylindrical shape having a diameter of about 4 mm and a length of about 5 mm. Used after.

(2) Comparative Example 1
The mixing step was performed using a twin screw extruder instead of the mixing and melting apparatus 1 in the above (1). That is, combinations and blending amounts of plant material (kenaf fiber B), non-acid-modified thermoplastic resin (PP; polypropylene), and acid-modified thermoplastic resin (acid-modified PP; maleic anhydride-modified polypropylene) shown in Table 1 In the twin screw extruder (Plastic Engineering Laboratory Co., Ltd., screw diameter 30 mm, L / D = 42), the material is inserted from the material inlet and extruded while kneading at a barrel temperature of 190 ° C. in the twin screw extruder. After being conveyed while being air-cooled, it was cut to obtain pellets made of a thermoplastic resin composition. The pellets were dried in an oven at 100 ° C. for 24 hours to obtain a thermoplastic resin composition of Comparative Example 1.
In this Comparative Example 1 as well, the plant material was introduced into a roller disk die type molding machine {manufactured by Kikukawa Iron Works Co., Ltd., model “KP280”, through-hole diameter 4.2 mm}, respectively. It was used after forming a cylindrical shape of about 4 mm and a length of about 5 mm.

(3) Comparative Example 2
Without using the mixing and melting apparatus 1 in (1) above, plant material (kenaf fiber B), non-acid-modified thermoplastic resin (PP; polypropylene), and acid-modified thermoplastic resin (acid-modified PP; maleic anhydride-modified polypropylene) ) Were dry blended with the combinations and blending amounts shown in Table 1 to obtain a thermoplastic resin composition (mixture of pellets) of Comparative Example 2.
In this comparative example 2 as well, the plant materials were introduced into a roller disk die type molding machine {manufactured by Kikukawa Iron Works Co., Ltd., model “KP280”, through-hole diameter 4.2 mm}, respectively. It was used after forming a cylindrical shape of about 4 mm and a length of about 5 mm.

[Plant materials]
“Kenaf fiber A”: vegetable fiber having an average fiber length of 0.8 mm (of the cut kenaf fiber, selected as a sieve under a 1.0 mm aperture plate sieve).
“Kenaf fiber B”: vegetable fiber having an average fiber length of 3.5 mm (of the cut kenaf fiber, on a sieve with a 3.0 mm aperture plate and with a 5.0 mm aperture plate sieve) Selected as below).
“Kenaf fiber C”: vegetable fiber having an average fiber length of 6.0 mm (of the cut kenaf fiber, on a sieve with a 5.0 mm aperture plate and with a 7.0 mm aperture plate sieve) Selected as below).
“Kenaf fiber D”: vegetable fiber having an average fiber length of 10.0 mm (a kenaf fiber cut to a width of 1 cm).
“Kenaf core”: non-fibrous plant material in the form of powder having an average particle size of 0.6 mm.

[Thermoplastic resin]
“PP”; polypropylene (non-acid-modified thermoplastic resin, manufactured by Nippon Polypro Co., Ltd., product name “Novatech NBX03HRS”).
Acid-modified PP; maleic anhydride-modified polypropylene (acid-modified thermoplastic resin, manufactured by Sanyo Chemical Industries, Ltd., product name “Yumex # 1001”, base resin is polypropylene, weight average molecular weight is 40,000, melt viscosity is 16,000 mPa · s, acid value is 26).

[2] Characteristic Evaluation of Thermoplastic Resin Composition Each thermoplastic resin composition of Examples 1 to 15 and Comparative Examples 1 to 4 obtained in [1] above was injected into an injection molding machine (Sumitomo Heavy Industries, Ltd., The injection filling pressure was measured when each thermoplastic resin composition was filled in a mold for obtaining various test pieces under the conditions of a cylinder temperature of 190 ° C. and a mold temperature of 40 ° C. . The results are also shown in Tables 1 to 4.

In addition, each of the thermoplastic resin compositions of Examples 1 to 15 and Comparative Examples 1 to 4 obtained in the above [1] was put into an injection molding machine (manufactured by Sumitomo Heavy Industries, Ltd., type “SE100DU”). Each thermoplastic resin composition was filled in a bar flow mold under the conditions of a cylinder temperature of 190 ° C., a mold temperature of 40 ° C., and an injection filling pressure of 150 MPa, and the length of the obtained molded body was measured. The results are also shown in Tables 1 to 4.

[3] Molding / Characteristic Evaluation of Thermoplastic Resin Molded Body The thermoplastic resin compositions of Examples 1 to 15 and Comparative Examples 1 to 4 obtained in the above [1] were injected into an injection molding machine (Sumitomo Heavy Industries, Ltd.). Made into a model “SE100DU”) and injection molded under conditions of a cylinder temperature of 190 ° C. and a mold temperature of 40 ° C. to obtain a rectangular plate-shaped test piece having a thickness of 4 mm, a width of 10 mm, and a length of 80 mm.
Then, the bending strength of each obtained test piece was 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 load was applied (based on JIS K7171). The results are also shown in Tables 1 to 4.

[4] Effect of Example From the results of Table 1, when a pellet mixture that was only dry blended as shown in Comparative Example 2 was injection molded, its injection filling pressure was as large as 112 MPa (bar flow flow length was 520 mm). And short). In addition, as shown in Comparative Example 1, even when injection molding is performed after mixing thermoplastic resin pellets and vegetable material pellets in advance using a twin screw extruder, the injection filling pressure is 110 MPa (bar flow flow length). 550 mm), which is almost the same as that of the dry blend of Comparative Example 2 alone.
On the other hand, when the mixing and melting apparatus was used as in Example 2, the injection filling pressure could be remarkably reduced to 72 MPa despite the same material composition as in Comparative Examples 1 and 2 (the bar flow flow length was 680 mm long). In addition, as shown in Example 3, it can be seen that even when the blending ratio of the plant material is increased to 70% by mass, the injection filling pressure can be suppressed to the same level as in Comparative Example 2 (the same is true for the bar flow flow length). A trend is observed).
Furthermore, the bending strength of the molded body obtained in Comparative Example 1 was 58 MPa, and the bending strength of the molded body obtained in Comparative Example 2 was 55 MPa. On the other hand, the bending strength of Example 2 was remarkably large at 68 MPa, although the material composition was the same as those of Comparative Examples 1 and 2. That is, by using the mixing and melting apparatus, it was possible to improve the mechanical properties while improving the fluidity.

From the results of Table 2 and FIG. 1 (the values of Comparative Example 3, Example 2, and Examples 4 to 7 are plotted), the bending strength could be remarkably improved by adding the acid-modified thermoplastic resin. However, the effect was almost saturated at a blending amount of about 7% by mass (about 7% by mass in the ratio to the whole thermoplastic resin). In addition, the fluidity could be remarkably improved by blending this acid-modified thermoplastic resin. Similar to the bending strength, this effect was almost saturated at a blending amount of about 7% by mass.

From the results of Table 3 and FIG. 2 (the values of Comparative Example 4 and Examples 8 to 11 are plotted), even if the blending amount of the acid-modified thermoplastic resin is constant, the plant fiber is blended with the plant material. It can be seen that the fluidity can be more effectively improved by the ratio. That is, as shown in FIG. 2, when the proportion of the vegetable fiber in the plant material is increased while the amount of the acid-modified thermoplastic resin is kept constant, a remarkable improvement in fluidity is recognized. When the proportion of the vegetable fiber is up to 33% by mass, an extremely remarkable improvement in fluidity is recognized, and when the proportion is 33% by mass or more, the effect becomes moderate. However, there is a drop in injection filling pressure of 8 MPa between 33 and 100% by weight. As shown in FIG. 1, the decrease in the injection filling pressure of 8 MPa is equivalent to the effect of increasing the ratio of the acid-modified thermoplastic resin in the thermoplastic resin from 1% by mass to 5% by mass, and the extremely high fluidity is improved. It turns out that the effect is acquired.
On the other hand, as the proportion of the vegetable fiber increases, the fluidity improves and the bending strength increases as shown in FIG. That is, the bending strength is increased by 9 MPa when the proportion of vegetable fiber is in the range of 0 to 100% by mass. As shown in FIG. 1, this is in contrast to the fact that the ratio of the vegetable fiber is improved only by 2 MPa no matter how much the acid-modified thermoplastic resin is increased from 2.5% by mass. It can be seen that it greatly contributes to the effect.

Injection filling of Comparative Example 4 (a thermoplastic resin composition consisting only of kenaf core and PP) and Example 8 (a system in which 2.5% by mass of acid-modified PP is added to Comparative Example 4) Comparing the pressure, Comparative Example 4 is 118 MPa, and Example 8 is 116 MPa. That is, when the kenaf core is used as the vegetable fiber, the decrease in the injection filling pressure due to the addition of the acid-modified thermoplastic resin is 1.7%.
On the other hand, Comparative Example 3 (thermoplastic resin composition consisting only of plant fiber and PP) and Example 2 (system in which 2.5% by mass of acid-modified PP was added to Comparative Example 3) In comparison, the injection filling pressure of Comparative Example 3 is 110 MPa, and Example 2 is 72 MPa. That is, when kenaf fiber is used as the vegetable fiber, the decrease in injection filling pressure due to the addition of the acid-modified thermoplastic resin is 35%, which is equivalent to 21 times the former.
In the present invention, the reason why such an effect is obtained is not clear, but in the present invention, a synergistic effect for improving the remarkable fluidity by using the vegetable fiber and the acid-modified thermoplastic resin together is obtained. You can see that

The method for producing a thermoplastic composition of the present invention and the method for producing a thermoplastic resin molded body of the present invention are widely used in the fields related to automobiles and fields related to architecture. Particularly suitable for interior materials, exterior materials and structural materials for automobiles, railway vehicles, ships and airplanes, etc. Especially as automotive products, suitable for automotive interior materials, automotive instrument panels, automotive exterior materials, etc. It is. Specifically, door base material, package tray, pillar garnish, switch base, quarter panel, armrest core material, automotive door trim, seat structure material, seat backboard, ceiling material, console box, automotive dashboard, various types Instrument panel, deck trim, bumper, spoiler and cowling. 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.

Claims

Production of a thermoplastic resin composition comprising a plant material and a thermoplastic resin, wherein the plant material and the thermoplastic resin are 100% by mass, and the plant material is contained in an amount of 50 to 95% by mass. A method,
A mixing step of mixing the plant material and the thermoplastic resin with a mixing and melting apparatus;
The method for producing a thermoplastic resin composition, wherein in the mixing step, 1 to 30% by mass of an acid-modified thermoplastic resin is used when the total amount of the thermoplastic resin is 100% by mass.
The method for producing a thermoplastic resin composition according to claim 1, wherein the plant material includes plant fibers.
The method for producing a thermoplastic resin composition according to claim 2, wherein the vegetable fiber has an average fiber length of 0.5 to 20 mm.
The method for producing a thermoplastic resin composition according to any one of claims 1 to 3, wherein the plant material is kenaf.
The method for producing a thermoplastic resin composition according to any one of claims 1 to 4, wherein the acid-modified thermoplastic resin has an acid value of 5 or more.
The method for producing a thermoplastic resin composition according to any one of claims 1 to 5, wherein the acid-modified thermoplastic resin has a weight average molecular weight of 10,000 to 200,000.
The mixing and melting apparatus includes a mixing chamber for performing the mixing and a mixing blade disposed in the mixing chamber,
The thermoplastic resin composition according to any one of claims 1 to 6, wherein in the mixing step, the thermoplastic resin melted by rotation of the mixing blade in the mixing chamber and the plant material are mixed. Manufacturing method.
The method for producing a thermoplastic resin composition according to any one of claims 1 to 7, further comprising a pelletizing step after the mixing step, wherein the mixture obtained in the mixing step is pressed and hardened without heating. .
A thermoplastic comprising a molding step of obtaining a molded body by injection molding of the thermoplastic resin composition obtained by the method for producing a thermoplastic resin composition according to any one of claims 1 to 8. Manufacturing method of resin molding.