JP2011184520A - Method for producing cellulose-based resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve all problems relating to discoloring, low molecular weight, remaining of an unmelted material, and failing to obtain desired physical properties, upon producing a cellulose-based resin composition in a kneading machine. <P>SOLUTION: The method for producing a cellulose-based resin composition comprises producing a resin composition by extruding a raw material through a kneader, the raw material containing a plasticizer and a resin material containing at least a granular cellulose-based resin. A twin-screw extruder 10 is used as the kneader in the method, the extruder having two kneading portions in the screws 14, where a shear rate of the kneading portion is adjustable into the range from 140 to 436 sec<SP>-1</SP>. In the two kneading portions, the barrel temperature of the kneading portion in an entrance side is set to be equal to or lower than the softening temperature of the resin material, while the barrel temperature of the kneading portion in an exit side is set to be equal to or higher than the softening temperature of the resin material, so that the kneading portion in the entrance side is used as a pulverizing zone 22 of the raw material while the kneading portion in the exit side is used as a mixing zone 26 of the raw material, and thereby, pulverization and dispersion-mixing of the raw material are continuously carried out in a single kneader. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing a cellulosic resin composition, and more particularly to a method for producing a cellulosic resin composition capable of enhancing the quality as a raw material for melt molding such as injection molding, extrusion molding, blow molding and the like.

  Petroleum synthetic resins such as polyethylene resin, polypropylene resin, vinyl chloride, polyamide, polystyrene resin, PET (polyethylene terephthalate) resin, and polycarbonate are widely used as raw materials for melt molding such as injection molding raw materials and extrusion molding raw materials. ing.

Although some of the daily necessities such as containers and films and industrial products made of such petroleum-based synthetic resins are recycled, most of them are disposed of by incineration or landfilling, thereby reducing global warming. This leads to the emission of a large amount of CO ₂ which is considered as a causative substance. Against this background, the idea of carbon neutral that does not further increase CO ₂ into the atmosphere has started to be emphasized, and substitution to a material synthesized by changing the resin material from a petroleum raw material to a natural raw material is progressing. In particular, polylactic acid resins fermented and synthesized from corn and sugarcane as raw materials have excellent mechanical properties and are most widely used. In addition, corn fermentation uses ethanol obtained as part of fuel as an alternative to gasoline.

  However, corn as a raw material grows livestock as an agricultural feed or is used for food by humans. If the amount of use is increased in the future, food shortages may occur. However, strictly speaking, there is an opinion that edible corn and corn for resin raw materials are different from each other because they are of different types. However, the production volume in granaries such as Australia is greatly reduced due to drought, which is thought to be the impact of climate change due to global warming, and the distribution volume is affected by speculative transactions. There is a problem of shortage.

  From such a background, a resin derived from a natural raw material using a non-edible raw material is required. Among these, cellulosic materials have been used for a long time, and there is no problem in supply. In addition, it has already been used in large quantities as a display material, has a sufficient track record as a normal polymer material, and has problems such as insufficient heat resistance of polylactic acid and hydrolysis in a use environment. Cellulosic resins have the potential to be solved, and their applications may be extended to fields where polylactic acid resins have not been available.

  However, cellulosic resins have a large melt viscosity and are difficult to use as raw materials for injection molding and the like even when used alone or mixed with other petroleum resins. For this reason, in order to use a cellulosic resin as a raw material for melt molding, it is necessary to add plasticizer to impart plasticity.

  Cellulosic resins are vulnerable to impact and are easily destroyed. Therefore, it is also important to change the physical properties of the cellulosic resin according to the application by adding a petroleum resin having characteristics not found in the cellulosic resin. For this reason, it is very important for the expansion of the use of a cellulose resin to produce a cellulose resin composition in which a plasticizer and further a petroleum resin are added to a cellulose resin.

  By the way, the manufacturer of the cellulose-based resin does not supply the powdery material for the reason of the manufacturing method of the cellulose-based resin, and supplies it in the form of irregular particles of about 1 mm to 30 mm. For this reason, in order to mix a cellulose resin with a plasticizer or a petroleum resin uniformly with a kneader, a pulverization step is required to make the cellulose resin into a powder before mixing.

  Conventionally, in order to produce a cellulosic resin composition in which a plasticizer or other resin is mixed with a cellulosic resin, the cellulosic resin raw material is previously powdered with a pulverizer (eg, a mill type, paddle type, etc.). The cellulose-based resin composition is produced by mixing with a plasticizer or petroleum-based resin, supplying the mixture to a kneader, for example, a uniaxial or biaxial kneader, dispersing, mixing, or increasing the particle size. It was.

  For example, Patent Documents 1 to 4 include related techniques for previously pulverizing a cellulosic polymer material before being supplied to a kneader with a pulverizer.

JP 2007-84713 A Japanese Patent Laid-Open No. 11-58483 JP 2008-93873 A JP 2003-128791 A

  However, since the cellulose-based resin is easily deteriorated by heating (decrease in molecular weight, coloring), in the conventional method for producing a cellulose-based resin composition in which the cellulose-based resin before being supplied to the kneader is pulverized in advance by a pulverizer, There is a drawback in that heat deterioration occurs until the cellulose resin is discharged from the kneader, and the cellulose resin is colored yellow or the molecular weight is lowered. On the other hand, if the cellulose resin and the plasticizer or petroleum resin are not sufficiently dispersed and mixed, an unmelted product may remain in the composition or a composition having desired physical properties may not be obtained. Such disadvantages occur. As a result, there is a problem that the quality as a molding material in the field of melt molding as a raw material for injection molding or extrusion molding is lowered.

  The present invention has been made in view of such circumstances. When a cellulose resin composition is produced with a kneader, the problem of coloring, the problem of lowering the molecular weight, the problem of unmelted matter remaining, the desired physical properties. It aims at providing the manufacturing method of the cellulose resin composition which can solve all the problems which cannot be obtained.

  In order to achieve the above object, in the method for producing a cellulose resin composition, a raw material containing at least a granular cellulose resin and a plasticizer are extruded from a kneader to produce a resin composition. As the kneading machine, a twin-screw kneading machine having two kneading parts on the screw and capable of adjusting the shear rate of the kneading part in the range of 140 to 436 sec-1 is used. The barrel temperature of the kneading part (close to the raw material charging side) is set to be equal to or lower than the softening temperature of the resin component in the resin material, and the barrel temperature of the outlet side (resin discharge side) kneading part is set to the resin in the resin material. By setting the temperature to be equal to or higher than the softening temperature of the component, the kneading part on the inlet side is used as the pulverization zone for the raw material, and the kneading part on the outlet side is used as the mixing zone for the raw material. To provide a method for manufacturing a cellulose resin composition which is pulverized between the dispersed and mixed, wherein the continuously performing the one kneader.

  Here, the kneading part refers to a processing zone provided with a screw element called a kneading disk on two screw shafts.

  In the present invention, a twin-screw kneader having two kneading sections on the screw and capable of adjusting the shear rate of the kneading section in the range of 140 to 436 sec-1 is used, and the barrel temperature of the kneading section on the inlet side is set as the raw material. It is used as a grinding zone by setting it below the softening temperature at which it does not plasticize. On the other hand, by setting the kneading part on the outlet side to be equal to or higher than the softening temperature of the resin material, the raw material is continuously pulverized and dispersed / mixed by one kneader.

  In this way, the raw material is continuously pulverized, dispersed and mixed in one kneader, so that the raw material temperature is raised by the shear heat generated when pulverized in the pulverization zone, and the raw material is mixed without being cooled. Supply to the zone. In the mixing zone, the resin material warmed in the pulverization zone can be mixed and dispersed while being heated and kept warm above its softening temperature. Therefore, in the method for producing a cellulose resin composition of the present invention, the process from pulverization to dispersion / mixing can be performed with a single thermal history.

  In contrast, in the conventional method for producing a cellulose resin composition in which the cellulose resin is pulverized in advance by a pulverizer before being supplied to the kneader, the raw material is preliminarily pulverized by the pulverizer and then cooled to around room temperature. Thereafter, it is dispersed and mixed in a kneader. Therefore, in the conventional method, during the period from pulverization to dispersion / mixing, two thermal histories (high temperature higher than the softening temperature of the resin material) during pulverization and during dispersion / mixing are received.

  Thereby, in this invention, the total calorie | heat amount added to a raw material from a grinding | pulverization start to dispersion | distribution and mixing completion can be reduced notably conventionally. In addition, the raw material can be sufficiently dispersed and mixed by continuously performing from pulverization to dispersion / mixing in one kneader, so that an unmelted product does not remain and a composition having desired physical properties is obtained. You can get things.

  Therefore, in the present invention, when producing a cellulosic resin composition with a kneader, the resin composition, which has been a problem in the past, such as coloring of the resin composition, a decrease in molecular weight and accompanying physical properties, and an unmelted product remain. Can solve all of the problems.

  In the present invention, it is preferable that the narrowest tip clearance in the grinding zone is wider than the narrowest tip clearance in the mixing zone.

  This is because the purpose of the pulverization zone is different from the zone where kneading is performed, and the raw material can be uniformly pulverized, and the heat generated by the pulverization needs to be as small as possible. Specifically, the tip clearance at the narrowest portion of the grinding zone is preferably set to 0.03 to 2 mm, and preferably 0.05 to 2 mm. On the other hand, the tip clearance at the narrowest part in the mixing zone is preferably set to 0.01 to 1 mm.

  The tip clearance means the clearance between the elliptical kneading disc provided in the screw and the inner surface of the barrel, and the narrowest portion indicates the clearance between the elliptical longitudinal direction of the kneading disc and the inner surface of the barrel.

  In the present invention, the particle size of the cellulosic resin before being charged into the biaxial kneader is in the range of 1 to 30 mm. This shows the particle size range of the cellulosic resin supplied from the manufacturer of the cellulosic resin. Cellulose resin with a particle size distribution is dispersed and mixed with plasticizers and petroleum resins. If it is not made into a powdery body, it cannot be mixed uniformly.

  In the present invention, the pulverization zone is preferably pulverized with the plasticizer added to the resin material. This increases the penetration rate of the plasticizer into the resin material due to the heat generated by pulverization, and not only can the plasticizer be uniformly mixed into the resin material, but also the cellulose resin that has penetrated the plasticizer softens, so heat generated by pulverization also occurs. Can be small.

  Moreover, since the pulverization zone originally uses the kneading part as the pulverization zone, it has an excellent mixing function. Therefore, if it grind | pulverizes in the state in which the plasticizer was added to the resin material, grinding | pulverization and mixing can be performed simultaneously and the uniform mixing of the plasticizer to the resin material can be promoted further.

  In the present invention, it is preferable that the raw material is pulverized and dried at the same time by providing an open vent at the rear of the pulverization zone and degassing volatile substances such as water vapor from the pulverized raw material. Thereby, since pulverization and drying of the raw material can be simultaneously performed, steps such as preliminary drying performed before the raw material is charged into the kneader can be reduced, and the manufacturing process can be simplified.

  Cellulosic resins contain more water than other petroleum resins, and the water tends to evaporate during dispersion / mixing in the mixing zone and remain as bubbles in the resin. In the present invention, an open vent is provided after the pulverization zone, and moisture in the resin evaporated by shearing heat or the like at the time of pulverization is released to the outside from the open vent. Hydrolysis can be prevented.

  In this invention, the said raw material is two types, the said cellulose resin and the said plasticizer, It is characterized by the above-mentioned. Further, the raw material is characterized in that it is three kinds of the cellulosic resin, polycarbonate and the plasticizer.

  This shows a preferred specific example of the raw material to which the present invention is applied, and can be applied particularly preferably in the case of a cellulose resin alone and in the case of a composite resin composed of a cellulose resin and a polycarbonate.

  According to the present invention, when a cellulose resin composition is produced with a kneader, all the problems such as coloring of the resin composition, lowering of the molecular weight and accompanying physical property deterioration, and remaining unmelted material are solved. be able to.

Explanatory drawing explaining the structure of the twin-screw extruder which is a kneading machine used for the manufacturing method of the cellulose resin composition of this invention. Explanatory drawing explaining the screw segment structure of a kneading part. Explanatory drawing explaining the difference of the heat history of the raw material of this invention and the conventional method Table showing conditions and results of Examples and Comparative Examples The graph which shows the relationship between the shear rate of a kneading machine, YI value, and molecular weight

  Hereinafter, preferred embodiments of a method for producing a cellulose resin composition will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic view showing the configuration of a biaxial kneader that is a kneader used in the method for producing a cellulose resin composition of the present invention. 1A is a side view, and FIG. 1B is a top view showing a twin screw.

  As shown in FIG. 1, two screws 14 and 14 are juxtaposed inside the barrel 12 of the twin-screw kneader 10, and each screw is rotated by a motor (not shown). The two screws 14 and 14 may be rotated in the same direction or in different directions, but are preferably rotated in the same direction.

  A raw material supply port 16 is opened on the upper surface of one end side in the barrel longitudinal direction of the biaxial kneader 10, and a raw material charging hopper 18 is provided in the raw material supply port 16. The inside of the barrel 12 is arranged in order from the hopper 18 side into a transport zone 20, a first kneading zone (grinding part) 22, a heating / plasticizing zone 24, a second kneading zone (kneading part) 26, and a pressurization / discharge zone 28. Divided. In FIG. 1B, black squares are shown in order to clarify the positions of the two kneading zones 22 and 26.

  Temperature adjusting means (not shown) for adjusting the temperature of each zone 20 to 28 is provided outside the barrel 12 constituting each of the zones 20 to 28, and the temperature of each zone 20 to 28 can be individually adjusted. It is like that. As the temperature adjusting means, an electric heater or a jacket through which hot water and cold water flow can be suitably used.

  Further, a screw element called a double thread or a single thread is provided on the screw shaft in the transport zone 20, the heating / plasticizing zone 24 and the pressurizing / discharging zone 28.

  On the other hand, as shown in FIGS. 2A and 2B, the screw 14 of the first and second kneading zones 22 and 26 has a screw element called an elliptical kneading disk 14B on the screw shaft 14A. Multiple intervals are set. And the rotational azimuth | direction phase of the kneading disk 14B provided in the two screws 14 and 14 is set so that it may differ continuously or periodically. As shown in FIG. 2B, the order kneading is such that the phase difference is continuously shifted and the phase shift direction is forward with respect to the resin discharge direction (easily discharged). That's it. The kneading disk 14B has a twist angle twisted in the same direction as the rotation direction of the screw shaft 14A and is sequentially shifted, and the twist angle is set to about 20 to 30 °, for example. The two screw shafts 14A are rotationally driven in a state in which the corresponding kneading disks 14B maintain a positional relationship in which the rotation period is shifted by 90 ° as shown in FIG.

  Also, the one where the phase difference is opposite to the resin discharge direction (resin tends to stay) is called reverse kneading (not shown). The one without this is called neutral kneading (not shown). As a result, a shearing action between the surfaces of the kneading disk 14B and a dispersing action due to the turning back effect by the discontinuous kneading disk 14B are generated, and the raw materials are dispersed and mixed. In addition, the arrow of FIG. 2 (A) shows the movement of a raw material.

  Thus, as a biaxial kneader having two kneading zones 22 and 26 in the screw 14, for example, a TEM series manufactured by Toshiba Machine Co., Ltd. or a TEX series manufactured by Nippon Steel Co., Ltd. can be suitably used.

  In the present invention, using the biaxial kneader 10 configured as described above as a kneader, a raw material containing a resin material containing at least a granular cellulose resin and a plasticizer is removed from the biaxial kneader 10. When producing the composition by extrusion, the barrel temperature of the first kneading zone 22 on the inlet side was set to be equal to or lower than the softening temperature of the resin material, so that it was used as a pulverization zone. In this case, it is preferable to grind the resin material and the plasticizer in the coexistence state because the plasticizer melts due to heat generated during the grinding and easily penetrates into the resin material.

  Further, by setting the barrel temperature of the second kneading zone 26 on the outlet side to be equal to or higher than the softening temperature of the resin material, it is used as a mixing zone for performing dispersion and mixing. Thus, the raw material was pulverized and dispersed / mixed continuously by one kneading extruder. Hereinafter, the first kneading zone 22 will be described as the pulverizing zone 22, and the second kneading zone 26 will be described as the mixing zone 26.

  In the twin-screw kneader 10 having the above structure, the shear rate of the pulverization zone 22 and the mixing zone 26 needs to be adjustable in the range of 140 to 436 sec-1. The shear rate here was calculated based on the clearance D in the direction perpendicular to the clearance C of the kneading disk 14B in FIG. This is because the cellulose resin is weak against heat, and when the shear rate exceeds 436 sec −1 and the shear heat generation becomes large, the cellulose resin is easily colored yellow. On the other hand, when the shear rate is lower than 140 sec-1, dispersion / mixing is not sufficiently performed, and unmelted material remains or desired physical properties cannot be obtained.

  In the present invention, it is preferable that the narrowest tip clearance in the grinding zone 22 is wider than the narrowest tip clearance in the mixing zone 26. This is because, unlike the mixing zone 26 in which the pulverizing zone 22 is dispersed and mixed, it is sufficient to ensure the chip clearance to such an extent that the raw materials can be uniformly pulverized. Specifically, the tip clearance at the narrowest portion of the pulverization zone 22 is set to 0.03 to 2 mm, preferably 0.05 to 2 mm. On the other hand, the tip clearance at the narrowest part in the mixing zone is preferably set to 0.01 to 1 mm.

  As shown in FIG. 2 (A), the tip clearance refers to the clearance between the elliptical kneading disk 14B provided on the screw 14 and the inner wall surface of the barrel 12, and the elliptical longitudinal direction of the kneading disk 14B and the inside of the barrel 12. The clearance C with the wall surface is indicated.

  Further, as shown in FIG. 1A, an open vent 30 is provided at the rear of the pulverization zone 22 to degas volatile substances such as water vapor from the pulverized raw material, thereby simultaneously pulverizing and drying. It is preferable.

  FIG. 3A shows the temperature change of the raw material in the present invention in which the raw material is continuously pulverized, dispersed and mixed with one kneading kneader (biaxial kneader 10). On the other hand, FIG. 3 (B) shows the temperature change of a conventional raw material in which the cellulose resin before being supplied to the kneading extruder is pulverized in advance by a pulverizer.

  In the present invention shown in FIG. 3 (A), the raw material which has been pulverized in the pulverization zone 22 and whose product temperature has increased due to heat generated by shearing heat generation, etc. is heated, conveyed and plasticized as it is without being cooled. It can be raised above the softening temperature of the resin material, which is the mixing temperature. Therefore, in the present invention, from pulverization to dispersion / mixing can be performed with a single thermal history.

  In contrast, in the conventional method shown in FIG. 3 (B), the raw material is preliminarily pulverized by a pulverizer to cool the product temperature, which has been raised by heat generation such as pulverization heat, to near room temperature. It is charged, heated and conveyed to increase the temperature and replasticize to reach the dispersion / mixing temperature. Then, it is dispersed and mixed in the mixing zone. In this case, the raw material softened to some extent by pulverization cannot be stably supplied to the kneader unless it is once cooled to near room temperature and cured. Therefore, in the conventional method, two thermal histories during pulverization and during dispersion / mixing are received between pulverization and dispersion / mixing.

  In addition, as can be seen from the comparison of the resin arrival temperature in the dispersion / mixing process in FIGS. 3 (A) and 3 (B), the conventional method in which pulverization and dispersion / mixing are performed in separate apparatuses is the same as the dispersion / mixing from pulverization. Compared to the present invention in which the above is performed by one kneading machine, it becomes higher. This is because when a resin material that has been crushed by a pulverizer and cooled once as in the prior art is heated again by a kneader, the resin material needs to exceed a temperature range of very high viscosity. As a result, in the conventional method, the shear heating value is increased as compared with the present invention in which the process from pulverization to dispersion / mixing is performed by one kneading machine, thereby increasing the resin reaching temperature. Further, if the shear rate in the kneader is lowered in order to suppress shearing heat generation, the dispersion state becomes worse and the physical properties are lowered.

  The coloring of the resin material depends on how high the temperature is reached and how long it stays at that temperature. Therefore, as shown in FIG. 3B, the conventional method is exposed to heat generation that causes coloring by the amount that the resin arrival temperature is higher than that of the present invention.

  As a result, in the conventional method, the time during which the raw material is subjected to heat increases, and a large amount of heat is required to raise the once cooled raw material to the dispersion / mixing temperature. Therefore, the total amount of heat received from pulverization to dispersion / mixing in the conventional method is significantly larger than that of the present invention. In other words, the present invention can remarkably reduce the total amount of heat applied to the raw material from the start of pulverization to the end of dispersion / mixing as compared with the conventional method. Since the raw material can be heated to the softening temperature or higher using heat generated by pulverization heat or the like during pulverization, the amount of heat required to raise the subsequent dispersion / mixing temperature can be reduced. Therefore, the amount of heat received by the raw material can be greatly reduced as compared with the conventional method.

  Therefore, when a cellulose resin composition is produced with a kneader (biaxial kneader 10), all of the problems such as coloring of the resin composition, lowering the molecular weight and accompanying physical property deterioration, and unmelted matter remaining. Can be solved.

  Although it does not specifically limit as a cellulose resin in this Embodiment, A cellulose ester is preferable and especially a diacetyl cellulose (DAC), a triacetyl cellulose (TAC), a triacetate butyrate (CAB), and a triacetate propionate (CAP) are preferable. Can be used. The particle size of the cellulosic resin supplied from the cellulosic resin manufacturer is generally supplied to the user as an irregular granule in the range of 1 to 30 mm.

  As the petroleum-based resin in the present embodiment, any resin can be used as long as it can compensate for the physical properties insufficient for the cellulose-based resin, but polycarbonate, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polybutylene. Naphthalate, poly-1,4-cyclohexanedimethylene terephthalate, and copolymers thereof can be preferably used. In the case of petroleum-based resin, it is often supplied from the manufacturer in both powder and granular form.

  Although it does not specifically limit as a plasticizer in this Embodiment, Trimethyl phosphoric acid, diethylene glycol dibenzoate, glyceryl polybenzoate, adipic acid-type polyester, adipic acid ester can be used preferably. Plasticizers are both powdery and liquid at room temperature.

  Next, how are the physical properties and state of the produced cellulose resin composition (hereinafter referred to as the composition) in the examples satisfying the production method of the cellulose resin composition of the present invention and the comparative examples not satisfactory? It was tested. The test was carried out by attaching a strand die to the outlet of the kneader and cutting the composition of the strand (bar-shaped) extruded from the strand die after cooling to produce pellets.

[material]
Diacetyl cellulose (L-70: manufactured by Daicel Chemical) was used as the cellulose resin, and polycarbonate (A1700: manufactured by Idemitsu Petrochemical) was used as the petroleum resin. As the plasticizer, either trimethyl phosphoric acid (manufactured by Daihachi Chemical) or diethylene glycol dibenzoate (Rikaflow LA100: manufactured by Shin Nippon Rika) was used.

  And Examples 1-4 and Comparative Examples 1-11 were performed on the test conditions shown below.

Example 1
In Example 1, the raw material composition was 70% by mass of diacetyl cellulose and 30% by mass of trimethyl phosphoric acid. And as conditions of a kneader (biaxial kneader 10), the barrel 12 set temperature in the pulverization zone 22 was set to 30 ° C. which is lower than the softening temperature of diacetyl cellulose, and the chip clearance C was set to 0.05 mm. On the other hand, the barrel 12 set temperature in the mixing zone 26 was set to 220 ° C., which is higher than the softening temperature of diacetylcellulose, and the tip clearance was set to 0.05 mm. Further, the shear rate in the pulverization zone 22 and the mixing zone 26 was set to 272 sec-1 which satisfies the range of 140 to 436 sec-1. The discharge resin temperature at the strand die discharge port in Example 1 was 265 ° C. The shear rate is adjusted by changing the number of rotations of the screw 14, and so on.

(Example 2)
Example 2 was the same as Example 1 except that the plasticizer was changed from trimethyl phosphate to diethylene glycol dibenzoate. That is, the effect of changing the plasticizer was examined. The discharge resin temperature at the strand die discharge port in Example 2 was 262 ° C.

(Example 3)
In Example 3, the raw material composition was 35% by mass of diacetyl cellulose, 50% by mass of polycarbonate, and 15% by mass of diethylene glycol dibenzoate. The conditions of the kneader (biaxial kneader 10) were the same as in Example 1 except that the shear rate was set to 436 sec-1 which is the upper limit of 140 to 436 sec-1. The discharge resin temperature at the strand die discharge port in Example 3 was 270 ° C.

Example 4
In Example 4, the same raw material composition as in Example 3 was used, and the shear rate of the kneader (biaxial kneader 10) was set to 140 sec-1 which is the lower limit of 140 to 436 sec-1 of the present invention. The other conditions are the same as in Example 1. The discharge resin temperature at the strand die discharge port in Example 4 was 265 ° C.

(Comparative Example 1)
Comparative Example 1 is a case where pulverization and dispersion / mixing are performed separately in separate apparatuses using raw materials having the same composition as in Example 1. That is, the kneading part pulverized with one first kneader (biaxial kneader), and the kneading part dispersed and mixed with one second kneader (biaxial kneader). The barrel set temperature, the tip clearance C, and the shear rate in the first kneading machine (pulverization) and the second kneading machine (dispersing / mixing) were set in the same manner as in Example 1. Comparative Example 1 is a test for comparison with Example 1 in which pulverization and dispersion / mixing are performed in one kneader. In Comparative Example 1, the discharge resin temperature at the first kneader outlet was 262 ° C., and the discharge resin temperature at the strand die outlet attached to the second kneader was 275 ° C.

(Comparative Example 2)
Comparative Example 2 is a case where the raw material having the same composition as Example 1 was used and processed only in the pulverization zone 22 of the kneader (biaxial kneader 10). That is, the kneading disk 14B in the mixing zone 26 of the kneading machine (biaxial kneader 10) was replaced with a double thread having only a conveying function. The barrel temperature, the tip clearance C, and the shear rate in the pulverization zone 22 are the same as those in the first embodiment. The discharge resin temperature at the strand die discharge port in Comparative Example 2 was 245 ° C.

(Comparative Example 3)
Comparative Example 3 is a case where the raw material having the same composition as that of Example 1 was used and processed only in the mixing zone 26 of the kneader (biaxial kneader 10). In other words, the kneading zone 14 of the kneading zone (biaxial kneader 10) of the kneader (biaxial kneader 10) was replaced with a double thread having only a conveying function. The barrel temperature, tip clearance C, and shear rate in the mixing zone 26 are the same as in Example 1. The discharge resin temperature at the strand die discharge port in Comparative Example 3 was 255 ° C.

(Comparative Example 4)
The comparative example 4 is a case where the shear rate is 850 sec-1 which greatly exceeds the upper limit of 140 to 436 sec-1 which is the condition range of the present invention, and other conditions are the same as those of the first embodiment. The discharge resin temperature of the strand die discharge port in Comparative Example 4 was 320 ° C.

(Comparative Example 5)
Comparative Example 5 is a case where the shear rate is significantly lower than the lower limit of 140 to 436 sec-1 which is the condition range of the present invention and is 87 sec-1, and other conditions are the same as in Example 1. The discharge resin temperature of the strand die discharge port in Comparative Example 5 was 250 ° C.

(Comparative Example 6)
Comparative Example 6 is the same as Example 1 except that the shear rate is greatly lower than 140 to 436 sec-1 which is the condition range of the present invention and is 87 sec-1, and the raw material composition is changed to Example 3. . The discharge resin temperature at the strand die discharge port in Comparative Example 6 was 250 ° C.

(Comparative Example 7)
Comparative Example 7 is a case where the barrel 12 set temperature of the pulverization zone 22 is set to 220 ° C., which is higher than the softening temperature of diacetyl cellulose, and other conditions are the same as in Example 1. That is, the barrel 12 set temperature in the grinding zone 22 does not satisfy the present invention. The discharge resin temperature at the strand die discharge port in Comparative Example 7 was 282 ° C.

(Comparative Example 8)
Comparative Example 8 is a case where the tip clearance C of the pulverization zone 22 is set to 3 mm, and other conditions are the same as in Example 1. That is, the chip clearance C in the grinding zone 22 does not satisfy the conditions of the present invention. The discharge resin temperature at the strand die discharge port in Comparative Example 8 was 240 ° C.

(Comparative Example 9)
The comparative example 9 is a case where the barrel 12 set temperature of the mixing zone 26 is set to 30 ° C. which is lower than the softening temperature of diacetyl cellulose, and other conditions are the same as in the first embodiment. That is, the barrel 12 set temperature of the mixing zone 26 does not satisfy the present invention. The discharge resin temperature at the strand die discharge port in Comparative Example 9 was 265 ° C.

(Comparative Example 10)
Comparative Example 10 is a case where the chip clearance C of the grinding zone 22 is set to 2 mm, and other conditions are the same as in Example 1. That is, the chip clearance C in the grinding zone 22 does not satisfy the conditions of the present invention. The discharge resin temperature at the strand die discharge port in Comparative Example 10 was 238 ° C.

(Comparative Example 11)
Comparative Example 11 is a case where the raw material composition is 100% by mass of diacetyl cellulose without using a dispersant, and other conditions are the same as in Example 1. That is, it is a case where a composition is produced without using a plasticizer. The discharge resin temperature of the strand die discharge port in Comparative Example 11 was 330 ° C.

  In addition, except the said conditions of Examples 1-4 and Comparative Examples 1-11, all are common.

[Evaluation items for composition quality]
<Strand appearance>
It was evaluated by visual observation whether or not there was an unmelted product in the obtained composition.

<Pellet color>
If the yellow index (YI value) of the pellet did not increase compared to that of the raw material, it was marked as ◯, and if it increased, it was marked as x.

<Molecular weight>
When the molecular weight distribution (Mw) of the pellet was a decrease of 10% or less compared to the value of the raw material, it was evaluated as “B” when it exceeded 10%.

<Charpy impact strength>
The strand resin was measured using a Charpy impact tester (JIS 7111). If the Charpy impact strength of the pellet was 5 kJ / m 2 or more, the result was ○, and if it was 5 kJ / m 2, the result was ×.

<Comprehensive evaluation>
In the comprehensive evaluation, when all the four items of strand appearance, pellet color, molecular weight, and Charpy impact strength are “good”, the comprehensive evaluation is “good”, and when there is even one “x”, the comprehensive evaluation is “poor”.

[Test results]
The test results are shown in the table of FIG.

  As can be seen from the table in FIG. 4, in Examples 1 to 4 that satisfy the method for producing the cellulose resin composition of the present invention, all evaluation items were “good” and the overall evaluation was also “good”.

  On the other hand, in Comparative Examples 1 to 11 which do not satisfy the method for producing a cellulose resin composition of the present invention, at least one of the four evaluation items was x. For this reason, comprehensive evaluation was set to x.

  Of particular note, as can be seen from the comparison between Example 1 and Comparative Example 1, Example 1 in which pulverization, dispersion, and mixing were continuously carried out with one kneading extruder, and two kneading extruders When pulverization and dispersion / mixing were performed separately, there was a difference in pellet color. That is, in Example 1, the pellet color was evaluated as ◯, and the YI value of the pellet was not increased as compared with the raw material, whereas in Comparative Example 1, the evaluation was x, and the YI value was increased.

  The reason for this is that, as described in FIG. 3, in Example 1, the raw material that has been pulverized in the pulverization zone and whose product temperature has risen due to the heat of pulverization or the like is not cooled once, but the temperature in the zone is not lower than the softening temperature of the resin material. Can be raised. On the other hand, in Comparative Example 1, since the raw material pulverized by the first kneader is once cooled to near room temperature and then mixed by being introduced into the second kneader, the heat history is repeated twice. It is considered that the raw material is more susceptible to thermal deterioration than the one-time heat history of 1.

  Further, as can be seen from the comparison between the shear rate of Examples 1 to 4 and the shear rate of Comparative Example 4, if the shear rate exceeds 436 sec −1, even a raw material to which a plasticizer is added is kneaded. The discharge resin temperature of the machine rises to 320 ° C. As a result, only the appearance of the strand was ◯, but the other three items of pellet color, molecular weight, and Charpy impact strength were x. On the contrary, as in Comparative Example 5, when the shear rate is too low and lower than 140, the dispersion and mixing in the mixing zone are not sufficiently performed. As a result, since the raw material is less susceptible to thermal deterioration, the pellet color and molecular weight are good, but the Charpy impact strength, which is an evaluation item of strand appearance and physical properties, which is an evaluation item of unmelted material, is x. This result was the same when the raw material composition was changed as in Comparative Example 6.

  FIG. 5 is a graph showing how the shear rate affects the pellet color and molecular weight. The horizontal axis in FIG. 5 represents the shear rate, the left vertical axis represents the YI value of the pellet color, and the right vertical axis represents the molecular weight. Curve A shows a change in YI value, and curve B shows a change in molecular weight.

  As can be seen from the curve A in FIG. 5, when the shear rate is increased and the shear rate exceeds 436 sec-1, the raw material temperature becomes 273 ° C. and the YI value increases rapidly. On the other hand, the molecular weight of curve B did not change even when the shear rate exceeded 436 sec-1, and began to decrease rapidly when the product temperature reached 287 ° C. exceeding 727 sec-1. Therefore, deterioration of the YI value and molecular weight can be prevented by setting the shear rate to 436 sec −1 or less.

  Further, even if the shear rate was less than 140 sec-1, there was no effect on the YI value and molecular weight, but unmelted material was visually observed. Therefore, it is appropriate to set the lower limit of the shear rate to 140 sec-1.

  In Comparative Example 1, the raw material was pulverized by a kneading extruder, but the same result can be obtained when the pulverization apparatus is a mill type or paddle type as in the prior art.

  DESCRIPTION OF SYMBOLS 10 ... Kneading machine (biaxial kneader), 12 ... Barrel, 14 ... Screw, 14A ... Screw shaft, 14B ... Kneading disk, 16 ... Raw material supply port, 18 ... Hopper, 20 ... Conveying zone, 22 ... First kneading Zone (grinding part), 24 ... Heating / plasticizing zone, 26 ... Second kneading zone (kneading part), 28 ... Pressurization / discharge zone, 30 ... Open vent

Claims (7)

In the method for producing a cellulose resin composition, a resin composition containing at least a granular cellulose resin and a raw material containing a plasticizer are extruded from a kneader to produce a resin composition.
As the kneading machine, a biaxial kneading machine having two kneading parts on the screw and capable of adjusting the shear rate of the kneading part in a range of 140 to 436 sec ⁻¹ is used.
By setting the barrel temperature of the kneading part on the inlet side to be equal to or lower than the softening temperature of the resin material, and setting the barrel temperature of the kneading part on the outlet side to be equal to or higher than the softening temperature of the resin material. The inlet side kneading part is used as the raw material pulverization zone and the outlet side kneading part is used as the raw material mixing zone, and the raw material pulverization and dispersion / mixing are continuously performed in one kneader. The manufacturing method of the cellulose resin composition characterized by performing to this.   2. The method for producing a cellulose resin composition according to claim 1, wherein a tip clearance in the narrowest portion in the grinding zone is wider than a tip clearance in the narrowest portion in the mixing zone.   The method for producing a cellulose resin composition according to claim 1 or 2, wherein the particle size of the cellulose resin before being charged into the biaxial kneader is in the range of 1 to 30 mm.   In the said grinding | pulverization zone, it grind | pulverizes in the state in which the said plasticizer was added to the said resin material, The manufacturing method of the cellulose resin composition of any one of Claims 1-3 characterized by the above-mentioned.   5. An open vent is provided at the rear of the pulverization zone, and volatile materials such as water vapor from the pulverized raw material are degassed, whereby the raw material is pulverized and dried simultaneously. Any one of these manufacturing methods of the cellulose resin composition.   The said raw material is two types, the said cellulose resin and the said plasticizer, The manufacturing method of the cellulose resin composition of any one of Claims 1-5 characterized by the above-mentioned.   The said raw material is three types, the said cellulose resin, a polycarbonate, and the said plasticizer, The manufacturing method of the cellulose resin composition of any one of Claims 1-5 characterized by the above-mentioned.

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