JP2011006609A - Microcellulose-based fiber-containing resin composition and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microcellulose-based fiber-containing resin composition in which the fibers are homogeneously dispersed in the resin even being the microfiber, and which has high fluidity and moldability even containing the fibers.SOLUTION: The microcellulose-based fiber-containing resin composition is produced by a production method including a high-speed stirring step for preparing a mixture of a microcellulose-based fiber assembly having an average fiber length (L) of 0.01-2 mm, an average fiber diameter (D) of 0.001-1 μm and a water content of 0.1-20 wt.%, with a thermoplastic resin by inserting both thereof into a mixer having a rotary blade and carrying out high-speed stirring, and a low-speed stirring step for granulating the obtained mixture by the low-speed stirring of the mixer under cooling. The microcellulose-based fiber assembly is obtained by a production method including a microfibrillation step for microfibrillating a cellulose-based fiber by subjecting a water dispersion of the cellulose fiber to the microfibrillation by a high-pressure homogenizer, a substitution step for substituting the water dispersion of the microfibrillated micro cellulose-based fiber with a hydrophilic organic solvent, a drying step for removing the solvent from the substituted dispersion, and a pulverization step for subjecting the obtained dried product to pulverization treatment.

Description

  The present invention relates to a resin composition containing fine cellulose fibers and a method for producing the same.

  Conventionally, in order to improve the mechanical strength of the resin molded body, it has been practiced to strengthen the resin by blending fibers. Among these, cellulose fibers are natural fibers, are biodegradable, and can be incinerated, so that they are useful reinforcing fibers from the viewpoint of environmental protection. However, since it is difficult to defibrate cellulose fibers uniformly, it is difficult to improve the mechanical strength of the resin molding by uniformly dispersing cellulose fibers in the resin.

  Therefore, in Japanese Patent Application Laid-Open No. 2007-84713 (Patent Document 1), cellulose fiber aggregates are fibrillated by high-speed stirring with a mixer, and further, a thermoplastic resin is added and stirring is continued. There has been proposed a method for producing a cellulose fiber-containing thermoplastic resin composition comprising a step of adhering a thermoplastic resin to a mixture to obtain a mixture, and a step of stirring the obtained mixture at a low speed while cooling. In the method of this document, a pulp sheet or a cut product thereof is used as the cellulose fiber aggregate.

  However, even in this method, since the fiber diameter of the cellulose fiber is large, the fluidity of the resin composition is lowered and the moldability of the resin molded body is also lowered.

  In addition, in the method of this document, when a microfibrillated product of cellulose fibers is used instead of a pulp sheet or a cut product thereof, the entanglement of the fibers is severe in the dried product, and thus a resin molded body in which microfibers are uniformly dispersed is manufactured. It is difficult to do. On the other hand, even in the slurry or suspension of microfibrillated product, there are many aggregates, the appearance is deteriorated, the handling property is difficult, and the productivity is low.

JP 2007-84713 A (Claims, Examples)

  Accordingly, an object of the present invention is to provide a microcellulose-based fiber-containing resin composition in which the fibers are evenly dispersed in the resin even in the case of microfibers, and the flowability and moldability of the resin composition containing the fibers are high, and the production thereof It is in providing the method and the resin molding formed with the said resin composition.

  Another object of the present invention is to provide a microcellulose-based fiber-containing resin composition in which deterioration of the appearance due to fiber aggregation is suppressed and the molded article has high mechanical strength, a method for producing the same, and a resin formed from the resin composition. The object is to provide a molded body.

  Still another object of the present invention is to provide a method for easily producing a resin composition in which fine cellulose fibers are uniformly dispersed.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have conducted a low-speed stirring while cooling a mixture obtained by high-speed stirring a specific fine cellulose-based fiber aggregate together with a thermoplastic resin, thereby producing a fine fiber. Even so, the present inventors have found that the fibers can be uniformly dispersed in the resin and the fluidity and moldability of the obtained resin composition containing microfibers can be improved, thereby completing the present invention.

  That is, in the method for producing a resin composition containing fine cellulose fibers according to the present invention, a mixer having rotating blades has an average fiber length (L) of 0.01 to 2 mm and an average fiber diameter (D) of 0.001 to 1 μm. A fine cellulose-based fiber aggregate and a thermoplastic resin having a content of 0.1 to 20% by weight and a high-speed stirring are performed, and a mixture of the two is prepared, and the resulting mixture is cooled with a mixer. It includes a low speed stirring step for granulation by low speed stirring.

  The microcellulosic fiber aggregate is a microfibrillation step in which an aqueous dispersion of cellulosic fibers is microfibrillated with a high-pressure homogenizer, and the aqueous dispersion of microfibrillated microcellulosic fibers is replaced with a hydrophilic organic solvent. Even if the moisture content is 0.3 to 10% by weight obtained by a production method including a substitution step, a drying step for removing the solvent from the substituted dispersion, and a pulverization step for pulverizing the obtained dried product. Good. In the preparation of the microcellulose-based fiber aggregate, the hydrophilic organic solvent may be at least one selected from the group consisting of ethyl alcohol, isopropyl alcohol, acetone, and methyl ethyl ketone. In the substitution step, the ratio of the hydrophilic organic solvent may be about 100 to 3000 parts by weight with respect to 100 parts by weight of water contained in the aqueous dispersion. In addition, the fine cellulose-based fiber aggregate is prepared by adjusting the aqueous dispersion before replacement with the hydrophilic organic solvent to a concentration of 2% by weight and stirring the mixture at 5000 rpm for 3 minutes and the viscosity of the aqueous dispersion after replacement. The ratio of the finely divided cellulose fiber to 2% by weight and the viscosity of the aqueous dispersion stirred at 5000 rpm for 3 minutes with a mixer was about the former / the latter = 1 / 1.5 to 1.5 / 1. May be. Furthermore, you may use the homogenizer provided with the crushing type | mold homo valve seat as said high pressure homogenizer.

In the production method of the present invention, the average peripheral speed of the rotating blades in the high-speed stirring step is 10 to 100 m / sec, and the average peripheral speed of the rotating blades in the low-speed stirring step is 1 to 30 m / sec. After melting the thermoplastic resin by the generated frictional heat and mixing both, the thermoplastic resin melted in the low-speed stirring step is cooled and solidified while stirring, and the thermoplastic resin has a melting point of 230 ° C. or lower. Even when at least one resin selected from the group consisting of an amorphous resin having a melt viscosity of 10 ² to 10 ⁵ poise (200 ° C., shear rate 100 sec ⁻¹ ) measured with a crystalline resin and a capillary ohmmeter is used. Good.

  The present invention also includes a resin composition containing fine cellulose fibers obtained by the above production method. Furthermore, the present invention includes a molded body formed of the resin composition.

  In the present invention, since a mixture obtained by stirring a specific microcellulose-based fiber aggregate together with a thermoplastic resin at a high speed is stirred at a low speed, the fibers can be evenly dispersed in the resin even if they are microfibers. The fluidity and moldability of the obtained resin composition containing fine fibers can be improved. Furthermore, the appearance deterioration due to the aggregation of the fine fibers can be suppressed, and the mechanical strength of the molded body formed from the obtained resin composition can be improved. Furthermore, in the method of the present invention, a resin composition in which fine cellulose fibers are uniformly dispersed can be easily produced.

FIG. 1 is a schematic cross-sectional view showing a process of homogenizing a dispersion containing fibers using a homogenizer. FIG. 2 is an enlarged cross-sectional view of a facing portion between the crushing type homovalve seat and the homovalve. FIG. 3 is a perspective view of a crushing type homo valve seat. FIG. 4 is a perspective view of a non-crushing homo valve seat.

  The production method of the present invention comprises a high-speed stirring step in which a fine cellulose-based fiber aggregate and a thermoplastic resin are put into a mixer and stirred at a high speed to prepare a mixture of both, and the resulting mixture is cooled at a low speed while being cooled by the mixer. And a low-speed stirring step for granulation.

[High-speed stirring process]
In the high-speed stirring step, as the stirring means, a mixer (stirrer) having a rotating blade as a stirrer is preferable because stirring can be easily performed with a high shearing force. Examples of such mixers include conventional mixers such as homomixers, homodispers, Henschel mixers, Banbury mixers, ribbon mixers, and V-type mixers.

  The shape of the rotary blade is not particularly limited, and for example, a paddle shape, a turbine shape, a propeller shape, or the like can be used. The number of rotating blades is not particularly limited, but is usually two blades of an upper blade and a lower blade, or three blades of an upper blade, an intermediate blade, and a lower blade. Furthermore, in such a mixer that combines a plurality of rotating blades, as the rotating blade, the upper blade is a kneading type, the lower blade is a high circulation / high load type, and the intermediate blade is a melt type. Different types may be combined using.

  The mixer is preferably a heater mixer provided with heating means.

  As such a mixer, for example, Henschel mixer (manufactured by Nippon Coke Kogyo Co., Ltd., “FM20C / I”, capacity 20 L), super mixer (manufactured by Kawata Corporation, “SMV-20”, capacity 20 L), etc. Commercial products can be used.

  In the high-speed stirring process, the micro cellulosic fiber aggregate and the thermoplastic resin may be added to the mixer at the same time, or one component may be added and then the other component may be added. It is preferable to introduce the thermoplastic resin after the introduction of the fine cellulose-based fiber aggregate from the viewpoint that the body can be appropriately dispersed and the uniformity of both can be improved. Furthermore, if necessary, the microcellulose-based fiber aggregate is stirred for a predetermined time (for example, 0.1 to 10 minutes, preferably 1 to 5 minutes) to defibrillate the microcellulose-based fibers, and then the thermoplastic resin. May be input. Such a defibrating step is effective when the fine cellulose-based fiber aggregate is obtained as a fine-grain spread fiber aggregate. Note that the microcellulose-based fiber aggregate in the present invention has a low degree of entanglement in spite of being microfibrillated, so that nano-sized fibers can be incorporated into the thermoplastic resin without providing a defibrating step. It is possible to disperse uniformly.

  In the high-speed stirring step, the average peripheral speed of the rotating blades during stirring is, for example, about 10 to 100 m / second, preferably 15 to 90 m / second, more preferably 20 to 80 m / second (particularly 30 to 70 m / second). is there.

  In this step, by stirring at such a high speed, the thermoplastic resin is melted by the generated frictional heat, and both can be mixed in a state where the cellulosic fibers are uniformly dispersed in the thermoplastic resin. If stirring is continued, the temperature in the mixer will continue to rise, and the power of the motor will increase. It is preferable to reduce the rotational speed by gradually or decelerating the stirring speed according to the increase in power and the temperature in the mixer, and in this case, it is also preferable that the average peripheral speed be in the above range. When stirring is continued in this state, the power increases again, so the mixture is discharged to the mixer used in the next low-speed stirring step to be connected. In the mixture used for the next step, the microcellulose fibers are dispersed substantially uniformly in the thermoplastic resin.

  In the high-speed stirring process, the mixer can be heated by a heating means in order to assist the temperature increase in the mixer and facilitate the production of the mixture of the microcellulose-based fiber aggregate and the thermoplastic resin. Although heating temperature can be selected according to the kind of thermoplastic resin, it is 100-160 degreeC, for example, Preferably it is 110-150 degreeC, More preferably, it is about 120-140 degreeC.

(Micro cellulosic fiber aggregate)
In the present invention, the fine cellulose-based fiber aggregate subjected to the high-speed stirring step has an average fiber length (L) of 0.01 to 2 mm, an average fiber diameter (D) of 0.001 to 1 μm, and a water content of 0.1 to 20. A weight percent microfibrillated cellulosic fiber assembly is used.

  Cellulosic fibers constituting this microcellulose-based fiber aggregate are not particularly limited as long as they are polysaccharide fibers having a β-1,4-glucan structure, and for example, cellulose fibers derived from higher plants [for example, Wood fiber (wood pulp such as conifers, hardwoods, etc.), bamboo fiber, sugarcane fiber, seed hair fiber (cotton linter, Bombax cotton, kapok, etc.), gin leather fiber (eg hemp, kouzo, mitsumata, etc.), leaf fiber (For example, natural cellulose fibers (pulp fibers) such as Manila hemp and New Zealand hemp)], animal-derived cellulose fibers (such as squirt cellulose), regenerated cellulose (such as rayon and cellophane), chemically synthesized cellulose fibers [ Cellulose acetate (cellulose acetate), cellulose propionate, cellulose Organic acid esters such as cellulose acetate propionate and cellulose acetate butyrate; inorganic acid esters such as cellulose nitrate, cellulose sulfate and cellulose phosphate; mixed acid esters such as cellulose nitrate acetate; hydroxyalkyl cellulose (for example, hydroxyethyl cellulose ( HEC), hydroxypropyl cellulose, etc.); carboxyalkyl cellulose (carboxymethyl cellulose (CMC), carboxyethyl cellulose, etc.); alkyl cellulose (methyl cellulose, ethyl cellulose, etc.); cellulose derivatives such as regenerated cellulose (rayon, cellophane, etc.), etc. It is done. The cellulosic fiber is a high-purity cellulose having a high α-cellulose content, for example, an α-cellulose content of 70 to 100% by weight (for example, 95 to 100% by weight), preferably 98 to 90%, depending on applications. It may be about 100% by weight. These cellulosic fibers may be used alone or in combination of two or more.

  Of these cellulosic fibers, wood fibers (wood pulp such as conifers and hardwoods), seed hair fibers such as cotton linters, and the like are preferable. In the present invention, cellulose that has been microfibrillated by mechanical shearing or the like is used as a raw material, and cellulose derived from bacteria having a nanometer size fiber diameter is not used as a raw material without being microfibrillated.

  The average fiber length (L) of the microcellulose fibers is, for example, about 0.01 to 2 mm, preferably about 0.02 to 1.5 mm, and more preferably about 0.05 to 1 mm (particularly about 0.1 to 0.8 mm). It is.

  The average fiber diameter (D) is, for example, about 0.001 to 1 μm, preferably about 0.01 to 0.8 μm, more preferably about 0.05 to 0.7 μm (particularly 0.1 to 0.5 μm).

  In particular, when homogenizing with a homogenizer equipped with a crushing type homovalve sheet described later, a uniform average fiber diameter (D) can be realized, for example, 10 to 100 nm (for example, 15 to 80 nm), more preferably 20 to It is about 60 nm (especially 25-50 nm). Moreover, the standard deviation of fiber diameter distribution is about 100 nm or less (for example, 1-100 nm), Preferably it is 3-50 nm, More preferably, it is about 5-40 nm (especially 10-30 nm). Further, the maximum fiber diameter of the microfiber is 1 μm or less (for example, 20 to 900 nm), for example, 500 nm or less (for example, 20 to 500 nm), preferably 30 to 300 nm, more preferably 40 to 200 nm (particularly 50 to 100 nm). ) In the present invention, the average fiber diameter, the standard deviation of the fiber diameter distribution, and the maximum fiber diameter are values calculated from a fiber diameter (about n = 20) measured based on an electron micrograph.

  The ratio (L / D) of the average fiber length (L) to the average fiber diameter (D) is, for example, about 1000 to 10,000, preferably 1200 to 7000, more preferably 1500 to 5000 (particularly 2000 to 4000). When the L / D value is in such a range, the microfibrils are relatively long, despite having a nano-sized average diameter, so that the degree of microfibrillation increases and the fibers are entangled. Also grows.

BET specific surface area of fine cellulosic fiber aggregate, 15~100m ² / g, preferably from 17~50m ² / g, more preferably 18~40m ² / g (particularly 20 to 30 m ² / g) approximately.

(Characteristics of micro cellulosic fiber aggregate)
The micro cellulosic fiber aggregate has a low water content. Specifically, as described above, the water content is in the range of 0.1 to 20% by weight, preferably 0.2 to 15% by weight, more preferably 0.3 to It is about 10% by weight (particularly 0.5 to 7% by weight). Microfibrillated microcellulose-based fiber aggregates are extremely thin and long microfibers as described above, and are thus dried products with a low water content, even for applications that hate moisture. It can be easily used without impairing the properties of the microfiber. In particular, the microcellulosic fiber aggregate has such a low water content and a high degree of fibrillation, but the fiber aggregation is suppressed.

  Further, the Canadian freeness value (Canadian standard freeness) of the fine cellulose fiber aggregate is 0 to 200 ml, preferably 0 to 100 ml, more preferably when measured using a 0.1% by weight fine fiber slurry. Is about 0 to 50 ml (particularly 0 to 1 ml). A lower Canadian freeness value indicates higher water retention and greater fibrillation. That is, the Canadian freeness value is also an index of filtration performance in relation to the entanglement of fibers due to fiber branching. The Canadian freeness value is a value measured according to JIS P8121 “Pulp Freeness Test Method; Canadian Standard Type”.

  In addition, regarding the water retention of the micro cellulosic fiber aggregate, the water retention rate with respect to its own weight after centrifugation is, for example, 100% by weight or more, preferably 200 to 1000% by weight, more preferably 300 to 800% by weight (particularly 400 to 600%). % By weight). The centrifugation condition is a condition obtained by centrifuging a 2% by weight aqueous suspension described later at 1000 G for 15 minutes.

  Aggregation is suppressed and the microcellulose-based fiber aggregate is not excessively entangled, and thus has a high dispersibility in water and can form a stable dispersion (or suspension). The viscosity of the suspension obtained by suspending microfibrous cellulose in water to a concentration of 2% by weight varies depending on the type of blades of the stirrer. For example, a juicer mixer (manufactured by Sanyo Electric Co., Ltd.) , “SM-L50”) (5000 rpm × 3 minutes), for example, 2000 mPa · s or more (for example, 2000 to 10000 mPa · s), preferably 3000 to 9000 mPa · s, more preferably It is about 5000 to 8000 mPa · s. The viscosity was measured using a BL type viscometer using a rotor No. 4 is a value measured as an apparent viscosity at 25 ° C. at a rotation speed of 30 rpm. If the degree of fibrillation is small or the fiber diameter is large, the dispersibility in water decreases, and a uniform suspension cannot be obtained, making it difficult to measure the viscosity.

  Further, the dehydration time of the microcellulose-based fiber aggregate is, for example, 1000 seconds or more when measured using a 0.5% by weight microfiber slurry in accordance with the test method for dewatering amount of API standard. , Preferably 1200 to 10000 seconds, more preferably about 1500 to 8000 seconds (particularly 1800 to 7000 seconds). The longer the dehydration time, the higher the average fiber length / average fiber diameter ratio, and the higher the water retention. When used as a fiber reinforced resin filler or binder, a large effect can be obtained in a small amount.

(Manufacturing method of fine cellulose fiber aggregate)
Microcellulosic fiber assembly is a microfibrillation process in which an aqueous dispersion of cellulosic fibers is microfibrillated with a high-pressure homogenizer, and the aqueous dispersion of microfibrillated microcellulosic fibers is replaced with a hydrophilic organic solvent. It is obtained by a production method including a step, a drying step for removing the solvent from the substituted dispersion, and a pulverizing step for pulverizing the obtained dried product.

(1) Microfibrillation step An aqueous dispersion of microcellulose fibers can be produced, for example, by microfibrillation of an aqueous dispersion of cellulose fibers having a specific fiber length by mechanical shearing force.

  A micro cellulosic fiber can be manufactured by microfibrillating a cellulose fiber having a specific fiber length. As the raw material cellulose-based fibers, cellulose fibers corresponding to the cellulosic fibers exemplified in the section of the microfibrillated cellulose-based fiber aggregate can be used. In addition, when using pulp as a raw material cellulosic fiber, the pulp is a pulp obtained by a mechanical method (crushed wood pulp, refiner ground pulp, thermomechanical pulp, semichemical pulp, chemiground pulp, etc.) or chemical Pulp (kraft pulp, sulfite pulp, etc.) obtained by a conventional method may be used, and beating fibers (beating pulp etc.) subjected to beating (preliminary beating) if necessary. You may use the raw material cellulose fiber individually or in combination of 2 or more types. The cellulosic fiber may be a fiber that has been subjected to a conventional purification treatment such as degreasing (for example, absorbent cotton). Furthermore, from the viewpoint of suppressing the entanglement of raw material fibers, realizing efficient microfibril formation by homogenization treatment, and obtaining uniform nanometer-sized microfibers, never dry pulp, that is, pulp without drying history (to be dried And pulp that has been kept wet).

  The average fiber length of the raw material cellulose fiber may be, for example, about 0.1 to 25 mm, preferably about 0.5 to 20 mm, and more preferably about 1 to 15 mm (particularly 2 to 10 mm). Moreover, an average fiber diameter may be about 0.1-100 micrometers, for example, Preferably it is 0.5-50 micrometers, More preferably, about 1-30 micrometers (especially 3-20 micrometers) may be sufficient. If the fiber length is too short, only microcellulosic fibers having a short fiber length can be obtained, and if the fiber length is too long, the microfibrillation treatment may not be sufficiently performed.

  The microfibrillation of the raw cellulosic fiber can be carried out by subjecting the raw material cellulosic fiber to conventional methods such as beating and homogenization. When cellulosic fibers are microfibrillated by beating, the cellulosic fibers such as pulp are beaten with a conventional beating machine such as beater, jordan, conical refiner, single disc refiner, double disc refiner, etc. Fiber can be obtained.

  In the present invention, usually, cellulosic fibers are often microfibrillated by homogenizing to produce microcellulosic fibers. If necessary, the cellulosic fibers may be beaten (preliminarily beaten) by the above method and then homogenized.

  More specifically, the cellulosic fibers are dispersed in water by stirring or the like, and this dispersion (or suspension) is homogenized. In order to increase the efficiency of the homogenization treatment while maintaining the fiber length as much as possible, it is preferable to disperse in water so as to loosen the individual fibers under conditions such that the fibers are not cut.

  The density | concentration (solid content density | concentration) of the cellulose fiber in a dispersion liquid is 0.001-30 weight%, for example, Preferably it is 0.005-25 weight%, More preferably, it is 0.01-20 weight% (especially 0.00. 1 to 15% by weight).

  In addition, you may perform the dispersion | distribution process of a cellulose fiber by a conventional means, for example, a mechanical stirring means (a stirring bar, a stirring bar, etc.), an ultrasonic disperser, etc.

  In the homogenization treatment, the cellulosic fibers are microfibrillated by subjecting the dispersion to a conventional homogenizer (homogenizer, particularly high-pressure homogenizer).

  The degree of microfibrillation and homogenization of the suspension using the high-pressure homogenizer depends on the pressure fed to the high-pressure homogenizer and the number of times the dispersion is passed through the high-pressure homogenizer (number of passes). Usually, it may be about 30 to 100 MPa, preferably about 35 to 80 MPa, and more preferably about 40 to 70 MPa. The number of passes or the number of treatments (number of passes through a small-diameter orifice described later) is, for example, about 5 to 40 times, preferably about 7 to 30 times, and more preferably about 10 to 25 times (especially 15 to 25 times). .

  In the present invention, in order to obtain a micro cellulosic fiber substantially free of fibers having a fiber diameter on the order of microns and having an average fiber diameter of a uniform nanometer size, a crushing type homo valve seat is used as a high-pressure homogenizer. A high-pressure homogenizer provided may be used. A homogenization process using a high-pressure homogenizer provided with a crushing type homovalve seat will be described below with reference to the drawings.

  FIG. 1 is a schematic view showing a process of homogenizing the dispersion with a high-pressure homogenizer equipped with a crushing type homo-valve seat, and FIG. 2 is an enlarged cross-sectional view of a facing portion between the crushing type homo-valve sheet and the homo-valve. FIG. 3 is a perspective view of a crushing type homo-valve seat. On the other hand, FIG. 4 is a perspective view of a non-crushing homo valve seat.

  The high-pressure homogenizer includes a hollow cylindrical impact ring 6, a hollow cylindrical convex portion 2 b of the homovalve seat 2 that is inserted and disposed on the upstream side of the impact ring 6, and a downstream side of the impact ring 6. The hollow cylindrical convex part 2b is provided with the columnar homo valve | bulb 5 inserted facing, and the said hollow cylindrical convex part 2b and the said columnar homo valve | bulb 5 have the same outer diameter. In addition, the inner wall on the downstream side of the hollow cylindrical convex portion 2b has a tapered portion (inclined surface) 2d that expands in the downstream direction, and the downstream end of the hollow cylindrical convex portion 2b has an inner diameter d and a thickness t of the end surface. A thin ring-shaped end face 2c having the shape is formed. Further, the ring-shaped end face 2c, the homo valve 5 and the impact ring 6 form a small diameter orifice (gap) 4.

  The crushing type homo-valve seat 2 is a hollow member having a cylindrical flow path 3 therein, and extends in a downstream direction from a hollow disc-shaped main body portion 2a having an inflow port 3a and an inner wall of the disc-shaped main body portion 2a. And it is comprised with the hollow cylindrical convex part 2b which has the outflow port 3b. Furthermore, as described above, the crushing type homovalve seat 2 is formed with the tapered portion 2d having an enlarged inner diameter, so that compared to the general (normal) noncrushing type homovalve seat 12 shown in FIG. The ring-shaped end surface 2c that forms the outlet 3b is formed thin.

  In such a homogenization process using a high-pressure homogenizer, as shown in FIG. 1, the dispersion containing the raw cellulose fibers 1 flows into the flow path 3 in the homovalve seat from the inlet 3 a of the crushing homovalve seat 2. After passing through the flow path 3, it passes through the small-diameter orifice 4 to become a dispersion containing fine cellulose fibers 7. Specifically, in the treatment by the high-pressure homogenizer, when the raw material cellulose fiber 1 pumped through the homogenizer at a high pressure passes through the small-diameter orifice 4 that is a narrow gap, the wall surface of the small-diameter orifice 4 (particularly the wall surface of the impact ring 6). By being collided with each other, it is divided by shearing stress or cutting action, and becomes a uniform nanometer-sized microfibrillated cellulosic fiber 7. In particular, when the dispersion liquid that has passed through the flow path 3 in the homo valve seat passes through the gap formed by the homo valve seat 2 and the homo valve 5, the flow speed of the dispersion liquid increases rapidly. The pumping pressure of the dispersion rapidly decreases in inverse proportion to the increase in. Therefore, the pressure difference of the dispersion liquid can be increased, the cavitation of the dispersion liquid that has passed through the gap becomes intense, and the raw cellulose fiber 1 is made uniform due to an increase in collision force with the wall surface in the small-diameter orifice 4 or collapse of the bubbles. It can be inferred that microfibrillation has been realized.

  In order to effectively perform such microfibrillation, it is possible to reduce the thickness of the end surface of the wall portion forming the outlet of the crushing type homovalve seat (the ring-shaped end surface at the downstream end of the hollow cylindrical convex portion). Specifically, specifically, the ratio between the inner diameter d of the downstream end of the hollow cylindrical convex portion in the crushing type homo-valve seat and the thickness t of the ring-shaped end surface of the downstream end is determined by the former / the latter = 100/1 5/1, preferably 80/1 to 6/1 (for example, 50/1 to 8/1), more preferably 30/1 to 10/1 (especially 20/1 to 12/1). When the ratio between the two is within this range, a rapid decrease in the pressure of the dispersion liquid passing through the gap between the homovalve seat and the homovalve can be realized, and the raw material cellulose fibers can be divided into nanometer-sized uniform fiber diameters. Although the thickness of the end surface of the wall part which forms an outflow port can be selected according to the aperture of an outflow port, it is 0.01-2 mm normally, Preferably it is 0.05-1.5 mm, More preferably, it is 0.1-1 mm. It is about (especially 0.2-0.8 mm).

  The interval or clearance of the small-diameter orifice (particularly, the interval between the end face of the convex portion of the homovalve seat and the homovalve) is, for example, about 5 to 50 μm, preferably 10 to 40 μm, more preferably 15 to 35 μm (particularly 20 to 30 μm). is there.

  In such a high-pressure homogenizer, the pressure for passing through the small-diameter orifice (or pressure for feeding the dispersion liquid to the high-pressure homogenizer (or treatment pressure)) can be selected from the range of about 30 to 200 MPa, preferably 35 to It may be about 150 MPa, more preferably about 40 to 140 MPa. In this invention, it can divide | segment into a nanometer size fiber diameter by pumping a dispersion liquid with such a high pressure with respect to the high voltage | pressure homogenizer provided with the crushing type | mold homo valve seat.

  Further, by repeatedly passing through the small-diameter orifice and colliding with the wall surface, the degree of miniaturization of the raw material cellulose fiber can be adjusted as appropriate. The number of treatments (or the number of passes) for passing through the small-diameter orifice can be selected from a range of, for example, about 5 to 100 times, preferably 10 to 80 times, and more preferably about 12 to 60 times.

  Furthermore, the processing pressure may be selected according to the number of times of processing. For example, when the processing pressure is high-pressure processing (for example, about 60 to 200 MPa, preferably about 80 to 150 MPa, more preferably about 100 to 130 MPa), The number of times is, for example, about 5 to 50 times, preferably about 10 to 40 times, more preferably about 12 to 30 times (particularly about 15 to 25 times). On the other hand, when the treatment pressure is a low-pressure treatment (for example, 20 to 80 MPa, preferably about 30 to 70 MPa, more preferably about 40 to 60 MPa), the number of treatments is, for example, 10 to 100 times, preferably 20 to 80 times. More preferably, it is about 30 to 70 times (particularly 40 to 60 times).

  Generally, in the homogenization treatment, if the treatment pressure is too high or the number of treatments is too high, the fiber is subjected to a large shearing force, causing the fiber to be cut or twisted, resulting in loss of fiber properties or fibrillation. In addition, since strong entanglement between the fibers occurs, the dispersibility of the fibers tends to decrease. On the other hand, in this invention, these problems can be eliminated by using a crushing type homo valve seat. In particular, it is effective to use never dry pulp as the raw material cellulose fiber.

  In the homogenizing step, a homogenizing process using a high-pressure homogenizer equipped with a non-crushing type homo valve seat may be combined. In particular, as a pre-process (preliminary process) of a homogenization process (particularly a high-pressure process of 60 MPa or more) using a high-pressure homogenizer equipped with the crushing-type homovalve seat, a homogenization process may be performed using a homogenizer equipped with a non-crushing homogenizer. . In the homogenization step, pretreatment with a high-pressure homogenizer equipped with a non-crushing type homo-valve sheet can improve the processing efficiency in the high-pressure homogenizer equipped with a crushing type homo-valve sheet.

  In the non-crushing type homo-valve seat, as shown in FIG. 4, a tapered portion is usually formed on the inner wall of the hollow cylindrical convex portion 12 b extending from the hollow disc-shaped main body portion 12 a of the homo-valve seat 12. First, the ratio between the inner diameter of the downstream end of the hollow cylindrical convex portion of the homovalve seat and the thickness of the ring-shaped end surface of the downstream end is usually the former / the latter = 3/1 to 1/1 (especially 2.5 / 1 to 1.5 / 1).

  In the high-pressure homogenizer provided with the non-crushing type homo-valve seat, the pressure for passing through the small-diameter orifice (or the pressure for feeding the dispersion to the high-pressure homogenizer (or processing pressure)) is, for example, 30 to 100 MPa, preferably 35 to It may be about 80 MPa, more preferably about 40 to 70 MPa. For example, the number of passes may be 10 to 40 times, preferably 12 to 30 times, and more preferably about 15 to 25 times.

  As a pretreatment for the homogenization treatment, the dispersion may be refined. In the refiner process, a disk refiner (single disk refiner, double disk refiner, etc.) can be used. The disc refiner has a disc clearance of about 0.1 to 0.3 mm, preferably about 0.12 to 0.28 mm, more preferably about 0.13 to 0.25 mm (for example, 0.14 to 0.23 mm). May be.

  The number of rotations of the disk is not particularly limited, and can be selected from a wide range of 1,000 to 10,000 rpm. For example, 1,000 to 8,000 rpm, preferably 1,300 to 6,000 rpm, more preferably 1, It may be about 600 to 4,000 rpm.

  In the refiner process, the number of processes (pass number) may be 1 to 20 times, preferably 2 to 15 times, and more preferably about 3 to 10 times (for example, 4 to 9 times).

  The degree of the beating treatment of the raw material cellulose fiber can be adjusted by the disk clearance and the number of refiner treatments. If the disk clearance is too narrow or the number of treatments is too high, the raw material cellulose fibers will receive a large shearing force, fibrillation will proceed, twisting and surface roughness will occur, and the fibers will tend to get entangled. The dispersibility of the obtained fibrillated fiber is lowered. On the other hand, if the disk clearance is too wide, the shearing force applied to the raw cellulosic fibers becomes small, and undivided portions remain.

  By such a method, the raw cellulosic fibers are efficiently microfibrillated, and nanofiber sized fiber diameters, relatively long fiber lengths, and high degree of branching, and complex fibrous fibers are stably suspended. It can be obtained in a liquid (water suspension) state. Such an aqueous suspension (slurry suspension) is further drained by a conventional draining method, for example, filtration, squeezing, centrifugation, etc. You may adjust to about -30 wt% (especially 5-20 wt%).

  In the present invention, the average fiber length (L) and the average fiber diameter (D) of the microcellulose fibers in this aqueous dispersion are suppressed because the destruction of the microfibril structure by the drying process is suppressed. It is substantially the same as the average fiber length and fiber diameter of the fiber assembly. Specifically, the ratio of the average fiber length of the cellulosic fibers in the aqueous dispersion of the raw material (before drying) and the average fiber length of the cellulosic fibers in the fiber assembly after drying is, for example, the former / the latter = It is about 1 / 1.5-1.5 / 1, preferably 1 / 1.4-1.4 / 1, and more preferably about 1 / 1.3-1.3 / 1. Furthermore, the ratio of the average fiber diameter of the cellulosic fibers in the aqueous dispersion of the raw material (before drying) and the average fiber diameter of the cellulosic fibers in the fiber aggregate after drying is, for example, the former / the latter = 1/1. It is about 5-1.5 / 1, preferably about 1 / 1.4-1.4 / 1, more preferably about 1 / 1.3-1.3 / 1.

  Further, the water retention ratio of the microcellulosic fiber aggregate with respect to its own weight after centrifugation, the viscosity of the suspension (dispersion liquid) having a concentration of 2% by weight, and the Canadian freeness value (CSF value) are almost the same before and after drying. For example, each value before drying / value after drying = 1 / 1.5 to 1.5 / 1, preferably 1 / 1.4 to 1.4 / 1, more preferably 1/1. About 3 to 1.3 / 1.

(2) Substitution step The obtained aqueous dispersion of microcellulose fibers is subjected to a substitution step. In the replacement step, water, which is a dispersion medium contained in the aqueous dispersion, is replaced with a hydrophilic organic solvent. That is, by adding a hydrophilic solvent to the aqueous dispersion of microfibrous cellulose having the aforementioned concentration, the fibrillated cellulose dispersion medium is replaced with water by a hydrophilic organic solvent.

Examples of the hydrophilic organic solvent include alcohols (C _1-4 alkanols such as methanol, ethanol, isopropanol and 1-butanol) and alkane diols (C _2-4 alkanes such as ethylene glycol, propylene glycol and butylene glycol). Diol, etc.), cellosolves (such as _C1-4 alkyl cellosolve such as methyl cellosolve, ethyl cellosolve), cellosolve acetates (such as _C1-4 alkyl cellosolve acetate such as ethyl cellosolve acetate), carbitols (methylcarbitol, ethyl, and the like _{C 1-4} alkyl carbitol such as carbitol), ketones (acetone, di _{C 1-4} alkyl ketones such as methyl ethyl ketone), ethers (dioxane, such as tetrahydrofuran Jo or chain _{C 4-6} ether, etc.) and the like. These solvents may be used alone or in combination of two or more.

Among these solvents, productivity, in terms of cost, C _1-4 alkanols such as ethanol or isopropanol, acetone, di-C _1-4 alkyl ketones such as methyl ethyl ketone are preferred. Especially, C _1-4 alkanols (especially isopropanol), such as ethanol and isopropanol, are preferable from the point of substitution efficiency. In the present invention, a hydrophobic organic solvent may be used in combination with these hydrophilic solvents as a solvent for substituting water. However, compatibility with water (mixability), environmental and sanitary From the aspect, it is preferable to use substantially no hydrophobic solvent.

  In order to replace the dispersion medium contained in the aqueous dispersion from water to a hydrophilic organic solvent, it is preferable to add a hydrophilic organic solvent in an amount equal to or more than that of water. The ratio of the hydrophilic solvent is, for example, water dispersion For example, it is about 100 to 5000 parts by weight, preferably 200 to 4000 parts by weight, and more preferably about 300 to 3000 parts by weight (particularly 500 to 2500 parts by weight) with respect to 100 parts by weight of water contained in the liquid. The ratio of the hydrophilic organic solvent to the fiber aggregate is, for example, 500 to 50000 parts by weight, preferably 1000 to 30000 parts by weight, and more preferably 2000 to 25000 parts by weight with respect to 100 parts by weight of the fiber aggregate (solid content). Degree.

  In the present invention, in order to improve the degree of substitution with the hydrophilic solvent, the substitution with the hydrophilic solvent may be repeated a plurality of times. The number of repetitions is usually about 1 to 5 times, preferably 2 to 4 times, more preferably about 2 to 3 times (particularly 3 times), from the balance between substitution efficiency and simplicity.

  When repeating replacement with a hydrophilic solvent, in order to easily improve the replacement efficiency, the dispersion of the hydrophilic organic solvent containing water is removed by a conventional liquid removal method, for example, filtration, pressing, centrifugation, etc. It is preferable to do this. Usually, after concentration to 2 to 20 times, preferably 5 to 15 times (or a solid content concentration of 5 to 50% by weight, particularly 10 to 40% by weight) by liquid removal, a hydrophilic organic solvent is further added. To do. The ratio of the hydrophilic organic solvent after the second time in the case of repeating is, for example, 100 to 5000 parts by weight, preferably 300 to 100 parts by weight with respect to 100 parts by weight of the solvent (total of water and hydrophilic organic solvent) contained in the dispersion. The amount is about 4000 parts by weight, more preferably about 400 to 3000 parts by weight (particularly 500 to 2500 parts by weight). The ratio of the hydrophilic organic solvent to the fiber aggregate is, for example, 500 to 50000 parts by weight, preferably 1000 to 30000 parts by weight, and more preferably 2000 to 25000 parts by weight with respect to 100 parts by weight of the fiber aggregate (solid content). Degree.

  In the present invention, in order to further increase the degree of substitution with the hydrophilic organic solvent and suppress aggregation due to excessive entanglement of the fine cellulose-based fibers, the hydrophilic organic solvent is added and the dispersion is stirred by mechanical shearing force. Is preferred. As means for applying the mechanical shearing force, conventional means such as mechanical stirring means (stirring bar, stirring bar, etc.), ultrasonic disperser, etc. can be used.

  Among these stirring means, a mixer having rotating blades exemplified in the section of the high-speed stirring step can be used because stirring can be easily performed with a high shearing force. In the present invention, by using such a mixer, the solvent can be replaced while the fiber assembly is defibrated. Therefore, even a microcellulose fiber highly microfibrillated with a high-pressure homogenizer can be used as a solvent. Can be replaced.

(3) Drying process The dispersion liquid substituted with the organic solvent is further subjected to a drying process. In the drying step, the solvent (mainly hydrophilic organic solvent) is removed from the substituted dispersion.

  Although the obtained micro cellulosic fiber is subjected to a drying step, the temperature required for drying is preferably higher from the point of removing the solvent (moisture) of the micro cellulosic fiber, but due to rapid volatilization of the solvent. From the viewpoint of suppressing the aggregation of highly microfibrillated microcellulose-based fibers and preventing thermal degradation, it is preferable to dry at a temperature as low as possible. A drying temperature is 30-150 degreeC, for example, Preferably it is 40-120 degreeC, More preferably, it is a 50-100 degreeC (especially 55-80 degreeC) grade. The drying time is, for example, about 1 to 24 hours, preferably 2 to 12 hours, more preferably about 3 to 10 hours (particularly 4 to 8 hours). As a drier, a conventional drier, for example, a Nauter drier, a shelf drier, a rotary mixer with a heating jacket, or the like can be used as necessary.

  The dried product is obtained as a massive fiber aggregate by entanglement between highly microfibrillated fibers.

(4) Pulverization process The obtained massive dried product is further subjected to a pulverization process. In the pulverization step, the tangled fibers can be easily unwound by pulverizing the lump-like dried product. In the present invention, since aggregation of the fiber assembly is suppressed even after drying, a fiber assembly that retains a high microfibril structure and has a low bulk density is obtained by pulverization with a conventional pulverizer. be able to.

  In pulverization, it is necessary to pulverize to such an extent that the shape of the microfiber after the microfibrillation treatment is not impaired. That is, the dried product desirably has a fiber length of about 60 to 100% (particularly 80 to 100%) with respect to the fiber length after the microfibrillation treatment. For pulverization, a conventional pulverizer such as a sample mill, a hammer mill, a turbo mill, an atomizer, a cutter mill, a bead mill, a ball mill, a roll mill, or a jet mill may be used. Of these, an impact pulverizer such as a sample mill or a hammer mill (particularly a sample mill having a swing-type hammer) is preferable from the viewpoint of suppressing the destruction of a fine fiber structure.

  By passing through such a pulverization step, the fine cellulose-based fiber aggregate of the present invention having the above-mentioned characteristics is, for example, 0.1 to 10 mm, preferably 0.3 to 5 mm, more preferably 0.5 to 3 mm. It is obtained as a linear or fine-grain spread fiber aggregate having an average diameter of about.

(Thermoplastic resin)
Examples of the thermoplastic resin include olefin resins (including cyclic olefin resins), styrene resins, (meth) acrylic resins, organic acid vinyl ester resins, vinyl ether resins, halogen-containing resins, polycarbonate resins, Polyester resins, polyamide resins, thermoplastic polyurethane resins, polysulfone resins, polyphenylene ether resins, cellulose derivatives (cellulose esters, cellulose carbamates, cellulose ethers, etc.), silicone resins, rubbers or elastomers (polybutadiene, polyisoprene) Diene rubber, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, acrylic rubber, urethane rubber, silicone rubber, etc.). These thermoplastic resins can be used alone or in combination of two or more.

Among these thermoplastic resins, a crystalline resin having a melting point of 230 ° C. or less and an amorphous resin having a melt viscosity of 10 ² to 10 ⁵ poise (200 ° C., shear rate 100 sec ⁻¹ ) measured by a capillary ohmmeter are used. At least one selected from the group is preferred.

Examples of the crystalline resin having a melting point of 230 ° C. or lower include olefin resins (for example, poly C _2-4 such as polyethylene, polypropylene, ethylene propylene copolymer, propylene-ethylene copolymer, ethylene-propylene-butene-1). Olefin resins), vinyl alcohol polymers (eg, polyvinyl alcohol, ethylene-vinyl alcohol, etc.), polyamide resins (eg, aliphatic polyamides such as polyamide 6, polyamide 11, polyamide 12, etc.), aromatic polyesters resin (e.g., poly C _2-4 alkylene arylate such as polybutylene terephthalate), aliphatic polyester-based resin (e.g., polyoxyethylene carboxylic acid type resins such as polylactic acid, polybutylene succinate, polybutylene succinate - Ajipe Poly C _2-6 alkylene carboxylates such as preparative copolymer resins, such as poly C _3-12 lactone resins such as polycaprolactone), cellulose esters (e.g., cellulose propionate, cellulose acetate, cellulose butyrate, cellulose Cellulose organic acid esters such as acetate propionate and cellulose acetate butyrate).

Examples of the amorphous resin having the melt viscosity include, for example, styrene resins [for example, polystyrene resins such as polystyrene (GPPS), impact polystyrene (HIPS), a mixture of GPPS and HIPS (MIPS), acrylonitrile- Styrene copolymer (AS resin), rubber-containing styrene resin such as acrylonitrile-conjugated diene-styrene copolymer (ABS resin, etc.)], acrylic resin [for example, poly (meth) acryl such as polymethyl methacrylate Acid C _1-4 alkyl ester resin, etc.].

  These thermoplastic resins preferably have moderate fluidity. For example, the melt flow rate (MFR) of the polypropylene resin is 230 ° C. and 21.6 N, for example, 20 to 200 g / It may be about 10 minutes (particularly 30 to 150 g / 10 minutes). Further, the MFR of the polyethylene resin may be, for example, about 10 to 200 g / 10 minutes (particularly 20 to 150 g / 10 minutes) under the conditions of 190 ° C. and 21.6 N, for example.

  The melt flow rate (MFR) of the polylactic acid resin may be, for example, about 0.5 to 200 g / 10 minutes (particularly 1 to 100 g / 10 minutes) at 190 ° C. and 21.6 N. The melt flow rate (MFR) of the polyamide-based resin may be, for example, about 0.5 to 200 g / 10 minutes (particularly 1 to 100 g / 10 minutes) at 190 ° C. and 21.6 N.

  The MFR of the rubber-containing styrene-based resin (ABS resin or the like) may be, for example, about 10 to 200 g / 10 minutes (particularly 20 to 150 g / 10 minutes) under the conditions of 220 ° C. and 100 N. The MFR of the polystyrene resin (GPPS or the like) may be, for example, about 5 to 100 g / 10 minutes (particularly 10 to 80 g / 10 minutes) under the conditions of 200 ° C. and 50 N.

  The total amount of the micro cellulosic fiber aggregate and the thermoplastic resin can be appropriately set according to the capacity of the mixer. The proportion of the fine cellulose fiber aggregate is, for example, 5 to 500 parts by weight, preferably 10 to 400 parts by weight, more preferably 50 to 350 parts by weight (particularly 100 to 300 parts by weight) with respect to 100 parts by weight of the thermoplastic resin. Part), and may be about 150 to 300 parts by weight.

  Furthermore, a compatibilizing agent and / or a lubricant may be blended in order to improve the mixing property between the microcellulose-based fiber aggregate and the thermoplastic resin. The compatibilizing agent and / or lubricant may be added to the mixer at the same time as the micro cellulosic fiber aggregate and / or the thermoplastic resin, and the micro cellulosic fiber aggregate and the thermoplastic resin are mixed to some extent with stirring. To the mixer.

  The compatibilizing agent can be selected according to the type of the thermoplastic resin, and examples thereof include a thermoplastic resin modified with a compound having a polar group. Examples of the thermoplastic resin constituting the compatibilizer include polyolefin resins (polyethylene, polypropylene, ethylene-propylene copolymer, propylene-butene copolymer, etc.), polyamide resins (polyamide 6, polyamide 12, etc.), and cyclic carbonization. Examples thereof include hydrogen resins (such as cyclic olefin copolymers) and styrene resins (such as polystyrene, AS resin, ABS resin, styrene-conjugated diene copolymers and / or hydrogenated resins thereof, styrene thermoplastic elastomers, and the like). Examples of the polar group include a carboxyl group, a carbonyl group (such as an ester group, an amide group, and an acid halide group), an acid anhydride group, an amino group, a hydroxyl group, a glycidyl group, and an oxazolyl group. These compatibilizers may be used alone or in combination of two or more. Among these compatibilizers, modified olefin resins such as acid-modified polypropylene are widely used.

  The proportion of the compatibilizing agent is, for example, 0.1 to 10 parts by weight, preferably 0.3 to 5 parts by weight, more preferably 100 parts by weight based on the total of the microcellulose-based fiber aggregate and the thermoplastic resin. About 0.5 to 4 parts by weight (particularly 1 to 3 parts by weight).

Examples of the lubricant include aliphatic hydrocarbon waxes (poly C _2-4 olefin waxes such as polyethylene wax and polypropylene wax, paraffin waxes, microcrystalline waxes, etc.), vegetable or animal waxes (carnauba wax, beeswax, shellac wax, and montan wax), higher fatty acids (e.g., myristic acid, palmitic acid, stearic acid, _{C 8-35} saturated fatty acids such as behenic acid, such as _{C 10-35} unsaturated fatty acids such as oleic acid), higher Fatty acid salts (for example, C _8-35 fatty acid metal salts such as barium laurate, calcium stearate, zinc stearate, magnesium stearate), higher fatty acid esters (for example, glycerin fatty acid ester, pentaerythritol fatty acid ester) C _8-35 fatty acid amides such as _ruthenium ), higher fatty acid amides (for example, C _8-35 fatty acid amides such as stearic acid amide, alkylene bis fatty acid amides such as methylene bis stearic acid amide, etc.), etc. Is mentioned. These lubricants can be used alone or in combination of two or more. Among these lubricants, C _10-24 fatty acid metal salts such as calcium stearate are widely used.

  The ratio of the plasticizer is, for example, 0.01 to 5 parts by weight, preferably 0.03 to 3 parts by weight, and more preferably 0 to 100 parts by weight in total of the microcellulose-based fiber aggregate and the thermoplastic resin. About 0.05 to 1 part by weight (particularly 0.05 to 0.5 part by weight).

[Low speed stirring process]
In the low-speed stirring step, the mixture obtained in the high-speed stirring step is granulated by stirring at a low speed while cooling with a mixer. That is, by the treatment in this step, the thermoplastic resin melted in the above step is solidified in a state of being uniformly mixed with fibers while being stirred at a low speed to obtain pellets.

  In this step, in order to increase the cooling efficiency of the mixer, it is preferable to use a separate mixer from the mixer used in the high-speed stirring step. As the mixer, a mixer having rotating blades exemplified in the section of the high-speed stirring step can be used, but a cooling mixer provided with a cooling means is preferable because stirring is performed while cooling. As such a mixer, for example, a commercially available product such as a cooling mixer (manufactured by Nippon Coke Kogyo Co., Ltd., “FD20C / K”, capacity 45 L) can be used.

  In the low speed stirring process, the average peripheral speed of the rotating blades during stirring is smaller than the stirring speed in the high speed stirring process, for example, 1 to 30 m / second, preferably 2 to 25 m / second, more preferably 3 to 20 m / second. (Especially 5 to 15 m / sec).

  The treatment in the low-speed stirring process can be terminated when the mixture of the microcellulosic fibers and the thermoplastic resin is solidified to such an extent that it can be handled as a molding material. In addition, since the thermoplastic resin once solidified when the temperature in the mixer rises too much due to generation of frictional heat, it is preferable to control the temperature in the mixer even in the low-speed stirring step.

[Microcellulosic fiber-containing resin composition and molded article]
The obtained resin composition containing fine cellulose fibers is a solidified product (granulated product) of a thermoplastic resin in which fine cellulose fibers are uniformly dispersed, and can be used as a material for a resin molded product. If necessary, this resin composition may be subjected to pulverization treatment, pelletizing treatment, etc. to adjust the particle size. For the pulverization, a known pulverizer such as a sample mill, a hammer mill, or a cutter mill may be used. Moreover, you may use a well-known pelletizing apparatus, for example, a pelletizer etc., for a pelletizing process.

  The fine cellulose-based fiber-containing resin composition of the present invention may be further combined with another thermoplastic resin (such as a resin for a molded body). In particular, the resin composition of the present invention may be used as a master batch, mixed (diluted) with a matrix resin, and used as a fiber reinforced resin (or fiber reinforced resin composition). As the other thermoplastic resin, the thermoplastic resin that can be used as the resin composition of the present invention can be used. From the viewpoint of compatibility with the resin composition, the same thermoplastic resin as that constituting the resin composition or It is preferable to use the same kind of thermoplastic resin. Furthermore, in the mixing with other thermoplastic resins, the compatibilizer may be blended.

  The microcellulose-based fiber-containing resin composition may contain a conventional additive as necessary. Examples of additives include stabilizers [antioxidants (such as hindered phenolic antioxidants), shrinkage inhibitors, antistatic agents, ultraviolet absorbers, heat stabilizers, weathering stabilizers, etc.], lubricants, mold release Agents, lubricants, impact modifiers, colorants (dyes and pigments, etc.), colorants, plasticizers, dispersants, flame retardants, antibacterial agents, antiseptics, fungicides, insecticides, deodorants, crystal accelerators May contain an agent, a crystal nucleating agent, and the like.

  The resin molded body of the present invention is formed of the above-mentioned resin composition containing fine cellulose fibers. Such a molded body can be obtained by melt-kneading the resin composition and molding by a conventional molding method (extrusion molding, injection molding, compression molding, etc.).

  Melt-kneading can be performed using a conventional method, that is, a conventional melt-kneader, for example, a single screw or vent type twin screw extruder. Prior to melt-kneading, the resin composition and other components can be obtained using a conventional method such as a mixer (such as a tumbler, V-type blender, Henschel mixer, Nauta mixer, ribbon mixer, mechanochemical apparatus, extrusion mixer). Ingredients (such as the additives mentioned above) may be premixed. The melt kneading temperature can be selected according to the type of the thermoplastic resin, and may be, for example, 70 to 300 ° C, preferably 80 to 280 ° C, and more preferably about 85 to 260 ° C.

  The obtained molded body has high strength because the fine cellulose fibers are sufficiently dispersed in the molded body (matrix resin or the like).

  The molded body may be a foam. As the foaming method, a conventional method such as a method using a reaction product gas, a method using a foaming agent, or the like can be used. The foam may be either closed cells or open cells, and the expansion ratio is, for example, about 1.02 times or more (for example, 1.05 to 3 times).

  The foaming agent includes a volatile foaming agent and a degradable foaming agent. Examples of the volatile blowing agent include gas [carbon dioxide (carbon dioxide), hydrocarbon (propane, butane, pentane, etc.), methyl ether, trifluorochloromethane, nitrogen, etc.], volatile liquid [water, ethers, etc. (Ethyl ether, petroleum ether), acetone, hydrocarbon (liquid propane, liquid butane, hexane), benzene] and the like.

  Examples of the decomposable foaming agent include organic acids or salts thereof (citric acid, sodium citrate, etc.), azo compounds (2,2′-azobisisobutyronitrile, azohexahydrobenzonitrile, azodicarboxylic acid amide, Diazoaminobenzene, etc.), sulfonyl hydrazide compounds [benzenesulfonyl hydrazide, p-toluenesulfonyl hydrazide, 4,4′-oxybis (benzenesulfonyl hydrazide), etc.], nitroso compounds (N, N′-dinitropentamethylenetetramine, N, N Organic compounds such as' -dinitroso-N, N'-dimethylterephthalamide) and inorganic compounds such as sodium bicarbonate, ammonium carbonate, and ammonium bicarbonate.

  The ratio of the foaming agent is 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight, and more preferably about 0.5 to 5 parts by weight with respect to 100 parts by weight of the resin composition.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In the following examples, “parts” or “%” are based on weight unless otherwise specified, and using the fine cellulose fibers, pellets and molded products obtained in Examples and Comparative Examples, A physical property test was conducted.

[moisture]
The microfibers obtained in Preparation Examples 1 and 2 were measured using a halogen moisture meter (HG63, manufactured by METTLER TOLEDO Co., Ltd.) for a replacement product with a hydrophilic organic solvent.

[2% viscosity]
Pure water is added to the fine cellulose fiber aggregate obtained in Preparation Examples 1 and 2, and a juicer mixer (manufactured by Sanyo Electric Co., Ltd., SM-L50) or homodisper (manufactured by Special Machine Industries Co., Ltd., Model L) ) At 5000 rpm for 3 minutes to prepare an aqueous dispersion having a total amount of 600 g containing 2% of fibrillated cellulose. No. 4 was used, and the apparent viscosity (mPa · s) at 25 ° C. was measured at a rotation speed of 30 rpm.

[Centrifuge retention rate]
For the fine cellulose fiber aggregates obtained in Preparation Examples 1 and 2, the dispersion (suspension) prepared by measuring the 2% viscosity was centrifuged at 1000 G for 15 minutes, then the weight was measured, and the water retention rate against its own weight ( %) Was calculated.

[Average fiber length of fine cellulose fibers]
The fiber length of the fine cellulose fiber aggregates obtained in Preparation Examples 1 and 2 was calculated by measuring the average fiber length peak using a Kajaani fiber length distribution meter (FS-200).

[Fiber diameter of fine cellulose fiber]
A 50000 times scanning electron microscope (SEM) photograph was taken of the microcellulose fibers obtained in Preparation Examples 1 to 3, and two lines were drawn at arbitrary positions across the photograph on the photograph taken. The average fiber diameter (n = 20 or more) was calculated by counting all crossing fiber diameters. The method of drawing a line is not particularly limited as long as the number of fibers crossing the line is 20 or more. Furthermore, the standard deviation of the fiber diameter distribution and the maximum fiber diameter were determined from the measured values of the fiber diameter. In the case of microfibers having a maximum fiber diameter of more than 1 μm, the calculation was performed using a 5000 times SEM photograph.

[Dehydration time]
The fine cellulose fiber aggregate obtained in Preparation Example 3 was measured for dehydration time in accordance with the test method for dehydration amount of API standard. That is, the fine cellulose fiber aggregate was 4 g in solid content, and 400 g of 0.5% slurry was prepared. This slurry was put into a metal container having a diameter of 76.2 mm and a height of 127.0 mm, a pressure of 0.7 MPa was applied, and the time until 200 ml of the retained water in the slurry was drained was measured.

[density]
About the molded object obtained by the Example and the comparative example, the density (g / cm < ³ >) was measured according to ISO1183.

[Bending strength and flexural modulus]
About the molded object obtained by the Example and the comparative example, the bending strength (MPa) and the bending elastic modulus (MPa) were measured according to ISO178.

[Charpy impact strength]
About the molded object obtained by the Example and the comparative example, Charpy impact strength (kJ / m < ² >) was measured using the test piece with a notch at 23 degreeC according to ISO179 / 1eA.

[Liquidity]
About the resin composition obtained by the Example and the comparative example, based on ISO1130, it measured on 190 degreeC and 10 N conditions.

[Appearance of molded body]
Among the cellulose fiber masses present on the surfaces of the molded bodies obtained in Examples and Comparative Examples, the number of cellulose fiber masses (pieces / 50 cm ² ) having a maximum diameter or maximum length of 1 mm or more was visually confirmed.

[Granulation time]
The time required for granulation was measured from the start of the high speed stirring process to the end of the low speed stirring process.

Preparation Example 1 (Preparation of aqueous dispersion of fine cellulose)
To 40 g of commercially available kraft pulp (average fiber length of 3 mm, average fiber diameter of about 12 μm), 20 L of water was added and stirred well to prepare a dispersion. The obtained dispersion was charged into a high-pressure homogenizer (trade name “15M-8TA” manufactured by Gorin Co., Ltd.) at room temperature, and passed through the apparatus 15 times under a pressure of 50 MPa to obtain fine fibrous cellulose. The obtained fiber had an average fiber length of 0.6 mm and an average fiber diameter of 0.03 μm. Next, dehydration was performed to make the solid content about 10%. The viscosity of the 2% concentration dispersion was 7000 mPa · s for the suspension dispersed with the juicer mixer and 5700 mPa · s for the suspension dispersed with the homodisper. Furthermore, Table 1 shows the results of measuring moisture and centrifugal water retention.

Preparation Example 2 (Preparation of dry microcellulose)
To 1 kg of the slurry-like suspension (water content 89.6%) obtained in Preparation Example 1, 20 liters of isopropanol was added, and 5 with a manual stirrer (trade name “UT1305”, manufactured by Makita Corporation). Dispersed with stirring for a minute. The obtained dispersion was drained by hand-drawing using a filter cloth for drainage until the solid content became 30%. This process was further repeated twice to finally obtain about 350 g of a cellulose fiber aggregate containing a solvent. This fiber assembly was dried at 80 ° C. for 15 hours by an explosion-proof dryer (trade name “SPH301S” manufactured by Tabai Espec Co., Ltd.), and then a small sample mill (manufactured by Hosokawa Micron Co., Ltd., product name “Pulverizer AP-S”). ) Was used, and classified using a mesh with a diameter of 1 mmφ. The water content (water content) with respect to the entire fiber was 4.91%. The results of measuring various characteristics are shown in Table 1.

Preparation Example 3 (Preparation of aqueous dispersion of fine cellulose fiber)
Using NBKP pulp (manufactured by Marusumi Paper Co., Ltd., solid content of about 50%), 100 liters of a slurry liquid containing 1% by weight of pulp was prepared. Subsequently, using a disk refiner (trade name “SUPERFIBRATER 400-TFS” manufactured by Hasegawa Tekko Co., Ltd.), a refiner-treated product was obtained by beating 10 times with a clearance of 0.15 mm and a disk rotation speed of 1750 rpm. Using the homogenizer (Gorin Co., 15M8AT) equipped with a crush-type homovalve sheet (the inner diameter of the downstream end of the hollow cylindrical convex portion / the thickness of the ring-shaped end surface = 16.8 / 1), The treatment was performed 50 times at a treatment pressure of 50 MPa. The average fiber diameter of the obtained microcellulose was 45.4 nm, the standard deviation of the fiber diameter distribution was 22.6 nm, the maximum fiber diameter was 80.2 nm, and the dehydration time was 2530 seconds.

  To 1 kg of the slurry suspension (moisture content 90.3%), 20 liters of isopropanol was added and dispersed by stirring for 5 minutes with a manual stirrer (trade name “UT1305”, manufactured by Makita Corporation). The obtained dispersion was drained by hand-drawing using a filter cloth for drainage until the solid content became 30%. This process was further repeated twice to finally obtain 350 g of a cellulose fiber aggregate containing a solvent. The fiber assembly was dried at 80 ° C. for 15 hours with an explosion-proof dryer (trade name “SPH301S” manufactured by Tabai Espec Co., Ltd.), and then the product “Pulverizer AP-S” manufactured by small sample Milhosokawa Micron Co., Ltd.) Was pulverized at 12000 rpm, and classified using a mesh having a diameter of 1 mmφ. The water content (water content) with respect to the entire fiber was 3.82%. The results of measuring various characteristics are shown in Table 1.

Preparation Example 4 (Preparation of cellulose sheet)
Pulp sheet having a width of 60 cm, a length of 80 cm and a thickness of 1.1 mm (manufactured by Nippon Paper Industries Co., Ltd., trade name “pulp NDP-T”, average fiber diameter of 25 μm, average fiber length of 1.8 mm, α-cellulose content of 90% ) Was cut into a width of 20 cm and a length of 80 cm.

Example 1
Heater mixer (Nippon Coke Kogyo Co., Ltd., trade name “Henschel Mixer FM20C / I”, upper blade: kneading type, lower blade: high circulation / high load type, with heater and thermometer, capacity 20L) 140 The mixture was heated to 0 ° C., 30 parts of the microcellulose fiber aggregate (dry microcellulose) obtained in Preparation Example 2 was added, and the mixture was stirred at an average peripheral speed of 50 m / sec. Immediately after the completion of the introduction of the fine cellulose fibers, 68 parts of polypropylene (manufactured by Sun Allomer Co., Ltd., trade name “J139”) was added, and stirring was continued at an average peripheral speed of 50 m / sec. The power of the motor at this time was 2.5 kW. When the temperature of the mixer reaches 120 ° C., 2 parts of a compatibilizing agent (manufactured by Sanyo Chemical Industries, Ltd., acid-modified polypropylene, product name “Yumex 1010”) and 0.1 part of a lubricant (calcium stearate) are added. The stirring was continued. At about 10 minutes, power started to increase. One minute later, the power increased to 4 kW, and the peripheral speed was reduced to a low speed of 25 m / sec. The power began to rise again as the slow agitation continued. 1 minute and 30 seconds after the start of low-speed rotation, the current value reached 5 kW, so the outlet of the mixer was opened and discharged to the connected cooling mixer.

  Cooling mixer (Nippon Coke Kogyo Co., Ltd., trade name “Cooler Mixer FD20C / K”, rotating blade: standard blade for cooling, water cooling means (20 ° C.) and thermometer, capacity 45L), average peripheral speed 10 m / second Stirring was started at a low speed, and the stirring was terminated when the temperature in the mixer reached 80 ° C. The mixture of cellulose fibers and polypropylene was solidified by the low-speed stirring process, and a granulated product (pellet) having a diameter of several mm to 2 cm was obtained.

  Using the obtained granulated material, a cylinder molding is extruded at 190 ° C. using a twin screw extruder (manufactured by Nikko Corporation, trade name “TEX30α”), and resin molding containing fine cellulose fibers is performed. Got the body. Formability (kneading property, extrudability) using a twin screw extruder was good. The results are shown in Table 2.

Example 2
In the same manner as in Example 1 except that polylactic acid (manufactured by Mitsui Chemicals, trade name “Lacia H-100”) is used instead of polypropylene (trade name “J139”, manufactured by Sun Allomer Co., Ltd.) A resin molded body containing cellulose fibers was obtained. The results are shown in Table 2.

Example 3
In the same manner as in Example 1, except that polyamide 12 (manufactured by Daicel Evonik Co., Ltd., trade name “Daiamide L1600”) is used instead of polypropylene (trade name “J139”, manufactured by Sun Allomer Co., Ltd.), a microcellulose fiber is used. A resin molded body containing was obtained. The results are shown in Table 2.

Example 4
It contains microcellulose fibers in the same manner as in Example 1, except that the microcellulose fiber aggregate (dry nanocellulose) obtained in Preparation Example 3 is used instead of the microcellulose fiber aggregate obtained in Preparation Example 2. A molded resin product was obtained. A good molded body was obtained in the same manner as in Example 1.

Comparative Example 1
Example except that the aqueous dispersion of microcellulose obtained in Preparation Example 1 (microcellulose dispersion) was used in a proportion of 30 parts in terms of solid content instead of the microcellulose fiber aggregate obtained in Preparation Example 2. In the same manner as in No. 1, a resin molded body containing fine cellulose fibers was obtained. The results are shown in Table 2.

Comparative Example 2
A heater mixer (Henschel mixer FM20C / I) was heated to 140 ° C., 30 parts of the cellulose sheet obtained in Preparation Example 4 was added, and the mixture was stirred at an average peripheral speed of 50 m / sec. At about 2 minutes, since the cellulose sheet changed to cotton, 68 parts of polypropylene (J139) was added and stirring was continued at an average peripheral speed of 50 m / sec. The power of the motor at this time was 2.5 kW. When the temperature of the mixer reached 120 ° C., 2 parts of a compatibilizer (Yumex 1010) and 0.1 part of a lubricant (calcium stearate) were added and stirring was continued. At about 10 minutes, power started to increase. One minute later, the power increased to 4 kW, and the peripheral speed was reduced to a low speed of 25 m / sec. The power began to rise again as the slow agitation continued. 1 minute and 30 seconds after the start of low-speed rotation, the current value reached 5 kW, so the outlet of the mixer was opened and discharged to the connected cooling mixer.

  Stirring was started in the cooling mixer (cooler mixer FD20C / K) at a low average peripheral speed of 10 m / sec, and the stirring was terminated when the temperature in the mixer reached 80 ° C. The mixture of cellulose fibers and polypropylene was solidified by the low-speed stirring process, and a granulated product (pellet) having a diameter of several mm to 2 cm was obtained.

  Using the obtained granulated material, a cylinder molding is extruded at 190 ° C. using a twin-screw extruder (manufactured by Nikko Co., Ltd., trade name “TEX30α”), and a resin molded body containing cellulose fibers. Got. Formability (kneading property, extrudability) using a twin screw extruder was good. The results are shown in Table 2.

  As is clear from Table 2, the resin compositions of the examples were excellent in mechanical properties, fluidity and appearance, and the granulation time was short. On the other hand, the resin composition of Comparative Example 1 had a poor appearance and a long granulation time. Moreover, the resin composition of Comparative Example 2 had low fluidity.

  The resin molded body of the present invention is a packaging material for electrical and electronic parts, building materials (wall materials, etc.), civil engineering materials, agricultural materials, automotive parts (interior materials, exterior materials, etc.), packaging materials (containers, cushioning materials, etc.) It can be applied to life materials (daily necessities, etc.).

  In addition, since the resin molded body of the present invention has high strength, space-related products [artificial satellites (artificial satellite bodies, parabolic antennas, solar cell frames, etc.), space shuttles (airframes, wings, remote control bars, luggage compartments) Etc.], aircraft parts (airframe, main wing, tail wing, rudder, etc.), automobile parts (body, hood, door, drive shaft, etc.), sports equipment (golf shaft, tennis racket frame, etc.), leisure equipment (fishing rod, etc.) ) Is also useful.

  Furthermore, if necessary, it can be spun and can be used for clothes and the like.

DESCRIPTION OF SYMBOLS 1 ... Raw material cellulose fiber 2 ... Crushing type | mold homo valve seat 3 ... Flow path of crushing type | mold homo valve seat 4 ... Small diameter orifice 5 ... Homo valve 6 ... Impact ring 7 ... Micro cellulosic fiber 12 ... Non-crushing type homo valve seat

Claims (9)

  In a mixer having rotating blades, an average fiber length (L) of 0.01 to 2 mm, an average fiber diameter (D) of 0.001 to 1 μm, and a water content of 0.1 to 20 wt% Microcellulosic fiber-containing resin including a high-speed stirring step in which a thermoplastic resin is added and stirred at a high speed to prepare a mixture of the two, and a low-speed stirring step in which the resulting mixture is cooled at a low speed while cooling with a mixer. A method for producing the composition.   A micro-cellulosic fiber assembly is a microfibrillation process in which an aqueous dispersion of cellulosic fibers is microfibrillated by a high-pressure homogenizer, and the aqueous dispersion of microfibrillated microcellulosic fibers is replaced with a hydrophilic organic solvent. 2. A water content of 0.3 to 10% by weight obtained by a production method comprising a step, a drying step of removing a solvent from the substituted dispersion, and a pulverization step of pulverizing the obtained dried product. The manufacturing method as described.   The production method according to claim 2, wherein the hydrophilic organic solvent is at least one selected from the group consisting of ethyl alcohol, isopropyl alcohol, acetone and methyl ethyl ketone.   The method according to claim 2 or 3, wherein in the substitution step, the ratio of the hydrophilic organic solvent is 100 to 3000 parts by weight with respect to 100 parts by weight of water contained in the aqueous dispersion.   The aqueous dispersion before substitution with a hydrophilic organic solvent is adjusted to a concentration of 2% by weight, the viscosity of the aqueous dispersion stirred at 5000 rpm for 3 minutes with a mixer, and the microcellulose fiber after substitution is adjusted to a concentration of 2% by weight. The ratio of the viscosity of the aqueous dispersion stirred at 5000 rpm for 3 minutes with a mixer is the former / the latter = 1 / 1.5 to 1.5 / 1. The production method according to any one of claims 2 to 4 .   The manufacturing method according to any one of claims 2 to 5, wherein a homogenizer provided with a crushing type homovalve seat is used as the high-pressure homogenizer. The average peripheral speed of the rotating blades in the high-speed stirring process is 10 to 100 m / second, and the average peripheral speed of the rotating blades in the low-speed stirring process is 1 to 30 m / second, and is thermoplastic due to frictional heat generated in the high-speed stirring process. After melting the resin and mixing both, the thermoplastic resin melted in the low-speed stirring step is cooled and solidified while stirring, and as the thermoplastic resin, a crystalline resin having a melting point of 230 ° C. or lower and a capillary meter The at least 1 type of resin selected from the group which consists of an amorphous resin whose melt viscosity measured by-is 10 < ² > -10 < ⁵ > poise (200 degreeC, shear rate 100sec < ^-1 >) is used. The manufacturing method as described.   A resin composition containing a fine cellulose fiber obtained by the production method according to claim 1.   The molded object formed with the resin composition of Claim 8.

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