JP2011116838A - Method for producing cellulose-containing thermoplastic resin, cellulose-containing thermoplastic resin and molded body of the same - Google Patents

Abstract

An object of the present invention is to easily handle fibrous cellulose, which does not cause discoloration or odor generation by heating during molding, and has good affinity at the interface between fibrous cellulose and a thermoplastic resin. Therefore, the present invention provides a cellulose-containing thermoplastic resin production method, a cellulose-containing thermoplastic resin, and a molded article thereof, which have good appearance, good strength characteristics of the molded article, and can be remolded, that is, recyclable.
In a method for producing a cellulose-containing thermoplastic resin, a thermoplastic resin and cellulose are melt-mixed in a batch type closed kneader having a stirring chamber provided with a rotating shaft provided with a rotating blade. , Cellulose is fibrous cellulose defibrated by a dry defibrator, the temperature in the stirring chamber at the time of melt mixing is 150 to 370 ° C, the pressure in the stirring chamber is 0.20 MPa or more up to the saturated water vapor pressure And the melt-mixing is stopped immediately after the rotational torque of the rotating shaft reaches the minimum value and starts to increase, the method for producing a cellulose-containing thermoplastic resin.
[Selection] Figure 1

Description

  The present invention relates to a method for producing a cellulose-containing thermoplastic resin containing fibrous cellulose, a cellulose-containing thermoplastic resin, and a molded article thereof.

  Fiber Reinforced Plastics (FRP) in which glass fiber, carbon fiber, etc. are dispersed in a plastic material is lightweight, high in strength, and good in durability. It occupies a great position in the fields of cutting-edge technologies such as wings, which are assumed to be used in extreme conditions, and in the fields of automobile and railway vehicle interior and exterior, housing equipment such as unit baths and septic tanks. However, since it is difficult to separate FRP from plastic materials and reinforcing fibers such as glass fibers and carbon fibers, FRP has a low recyclability, and glass fibers remain as residues even after incineration. Yes, when considering the life cycle cost at the same time as the environmental load, the material may become more expensive than it seems.

  Therefore, in addition to the cost aspect, a material in which fibrous cellulose is dispersed in a plastic material has been developed for the use of general building materials and general molded products due to the recent increase in recycling movement. In particular, many plastic materials use a thermoplastic resin such as polyolefin. Initially, these materials are waste plastics discharged from plastic molding plants and waste plastics collected from the city as raw materials for plastic materials, and wood materials such as waste paper and building wastes collected from the city are also used as fibrous cellulose. Many were proposed as a combination of raw materials. Currently, the use of composite materials of woody materials and plastics as fibrous cellulose is prosperous in Europe and the United States, especially in North America, manufactured on a scale of 1 million tons per year, most of which is used as exterior deck materials. Yes. These are called Wood-Plastic-Composites, Wood-Polymer Compositions, Woodfiber-Polymer Compositions, and the like. In these, the fibrous cellulose is not a bleached pulp or the like having a high purity, but is often a wood material that has not been pretreated such as a plant material chip (see, for example, Patent Document 1).

  Recently, however, high strength, high elasticity, and low thermal expansibility of fibrous cellulose have attracted attention, and fibrous cellulose has attracted attention as a reinforcing fiber for plastic materials. In particular, in the field of plastic materials, in the field of bioplastics such as polylactic acid, the use of which has become widespread in recent years, in order to supplement the strength characteristics of bioplastics, compounding with fibrous cellulose such as kenaf fibers has been studied and has already been put into practical use. It has become.

  On the other hand, as a manufacturing method in which fibrous cellulose and a plastic material are combined, generally, paper, plant material, and the like are defibrated and pulverized, and then melt mixed with the plastic material. A general defibrator or pulverizer is used for defibration or pulverization, or when defibrating or pulverizing in a state of being dispersed in water, a high-pressure homogenizer or a stone mill type friction machine is used. . In addition, a batch type high-speed kneading device such as a Henschel mixer (registered trademark), a continuous kneading device such as a uniaxial kneading and extruding device or a biaxial kneading and extruding device is used for melt mixing of the fibrous cellulose and the plastic material. (For example, see Patent Documents 2 and 3). When a batch-type high-speed kneading apparatus is used, it has been proposed that after the melt mixing, the mixture is granulated by stirring at a low temperature and a low speed (for example, see Patent Document 4).

  Furthermore, some batch-type high-speed kneaders melt and mix the coarsely pulverized cellulose material and thermoplastic resin under high-temperature and high-pressure conditions without going through the fiber cellulose defibrating process. There has also been proposed a high-speed kneading apparatus in which cellulose material is defibrated in the process and dispersed in a thermoplastic resin as fibrous cellulose (see, for example, Patent Documents 5 and 6). Furthermore, melt mixing of an aqueous dispersion of microfibrillated cellulose nanofibers and a thermoplastic resin has been proposed with this apparatus (see, for example, Patent Document 7).

JP-A-8-118452 JP-A-1-118425 JP 2007-84713 A JP 2009-1597 A International Publication No. 2004/076044 Pamphlet JP 2008-93831 A JP 2009-29927 A

  As described in Patent Documents 3 and 4, before the melt mixing with the thermoplastic resin, the appearance of the molded body made of the cellulose-containing thermoplastic resin obtained by the production method in which the fibrous cellulose is defibrated, Good enough that almost no fiber clumps can be found. However, since the thermoplastic resin is only adhered to the fibrous cellulose by melt-mixing with a high-speed kneader, the hydrophilic hydrophilic cellulose and the non-hydrophilic thermoplastic resin have a low affinity. When a molded body is formed, voids are generated at the interface between the fibrous cellulose and the thermoplastic resin inside the molded body, and a dense molded body cannot be produced. For this reason, the molded body may be distorted or the molded body may be warped.

  On the other hand, Patent Document 5 discloses a method for producing a cellulose-containing thermoplastic resin using a high-speed kneading apparatus, but the cellulose-based material used therein does not need to be adjusted in advance such as a moisture content, and is simply a small piece. It is described that it may be made into pieces or strips. However, in the method for producing a cellulose-containing thermoplastic resin described in Patent Document 5, the range of variation in the shape and size of the cellulose material dispersed in the thermoplastic resin is large. In particular, variations in strength characteristics of the molded product contained in the molded product may increase, and the cellulosic material may be damaged by heat applied during molding, causing the molded product to turn brown or give off a burning odor. Further, when the molded body is pulverized and used again as a molding material, the cellulose contained again is heated, so that the cellulose is deteriorated and discoloration and a strange odor are further increased.

  Moreover, in the manufacturing method of the resin for injection molding described in Patent Document 6, the fibrous cellulose must be a plant piece containing lignin. For this reason, the color of the molded product becomes woody, and the plant pieces contained therein are easily burnt and odor is likely to be generated by heating during molding. Furthermore, in Patent Document 7, in order to microfibrillate fibrous cellulose to cellulose nanofibers, it is necessary to process a lot of time with a friction machine, a grinder or the like, and the obtained cellulose nanofibers are Due to the aqueous dispersion, melt mixing takes a very long time.

  In addition, the cellulose fiber receives a shearing force and an impact force from the kneading apparatus even during melt mixing. When a single fiber is subjected to the same shearing force, a fiber piece having a small fiber length and fiber diameter generally has a smaller shearing force due to a larger shearing force per unit cell volume of cellulose. Tend to be. Even in the case of cellulose nanofibers with a fiber diameter smaller than 100 nm that have been pre-treated, they are subjected to shearing force and impact force during melt mixing, but the nanofibers and microfibril parts become finer and finer, and the aspect ratio ( The length / diameter) also decreases, and the strength of the molded body cannot be maintained. In addition, since the cellulose gradually disintegrates due to self-decomposition from around 300 ° C. at the time of melt mixing, the fiber length further decreases with finer fibers. In any case, when fibrillated cellulose fibers are subjected to such melt mixing, handling such as shearing force and impact force applied during kneading and temperature control is difficult.

  Therefore, the problem of the present invention is that the fibrous cellulose is easy to handle, the molded body does not discolor or generate odor due to heating during molding, and further, at the interface between the fibrous cellulose and the thermoplastic resin. Since the affinity is good, the appearance is good, the strength properties of the molded article are good, and the method for producing a recyclable cellulose-containing thermoplastic resin, that is, the cellulose-containing thermoplastic resin and its It is to provide a molded body.

As a result of intensive studies, the present inventors have found that the above-described problems can be solved by the present invention described below.
[1] In a method for producing a cellulose-containing thermoplastic resin, a thermoplastic resin and cellulose are melt-mixed by a batch-type closed kneader having a stirring chamber provided with a rotating shaft provided with rotating blades. Is a fibrous cellulose defibrated by a dry defibrator, the temperature in the stirring chamber during melt mixing is 150 to 370 ° C, the pressure in the stirring chamber is between 0.20 MPa and the saturated water vapor pressure And the manufacturing method of the cellulose containing thermoplastic resin characterized by stopping melt-mixing immediately after the rotational torque of a rotating shaft reaches the minimum value and starts to raise.
[2] The method for producing a cellulose-containing thermoplastic resin according to [1], wherein the cellulose is fibrous cellulose obtained by defibrating chemical pulp with a dry defibrator.
[3] The method for producing a cellulose-containing thermoplastic resin according to the above [1] or [2], wherein the moisture content of the cellulose is 5 to 30% by mass.
[4] The method for producing a cellulose-containing thermoplastic resin according to the above [1], wherein the mass ratio of the cellulose and the thermoplastic resin is 10/90 to 70/30.
[5] A cellulose-containing thermoplastic resin produced by the method for producing a cellulose-containing thermoplastic resin according to any one of [1] to [4].
[6] A molded article containing the cellulose-containing thermoplastic resin according to [5].

  When the cellulose and the thermoplastic resin are melt-mixed to obtain a cellulose-containing thermoplastic resin, the cellulose fiber receives a shearing force and an impact force from the kneading apparatus. When a single fiber is subjected to the same shearing force, in a fiber piece having a small fiber length or fiber diameter, the shearing force acting on a unit cell volume of the cellulose is larger, so that fine fibers are generally finer. There is a tendency. In terms of the strength reinforcing effect of the cellulose fiber contained in the thermoplastic resin molded product, the cellulose fiber has a larger aspect ratio than that having a small aspect ratio (fiber length / fiber diameter) such as granular or powdery. The one with a greater reinforcement effect. That is, a molded article having higher strength can be obtained by uniformly dispersing a large number of cellulose fibers having a high aspect ratio and a short fiber length or a small fiber diameter in a thermoplastic resin. However, if the fiber length is short or the fiber diameter is small as described above, the aspect ratio of the cellulose fibers proceeds in the direction of decreasing during the melt mixing, and the desired molded body strength cannot be obtained. Therefore, in the present invention, it has been found that a decrease in strength of a molded product can be prevented by using fibrous cellulose defibrated by a dry defibrating machine. The fibrous cellulose used in the present invention has a long fiber length because it has been defibrated by a defibrating machine, and is hardly affected by shearing force or impact force during melt mixing. Further, in the present invention, the temperature in the stirring chamber of the kneading apparatus is 150 to 370 ° C. and the pressure in the stirring chamber is 0.20 MPa using a batch type closed kneading apparatus. As described above, since melt mixing is performed under conditions up to the saturated water vapor pressure, the dispersion state of the fibrous cellulose in the thermoplastic resin is uniform, and in addition, the shape of the fibrous cellulose is maintained uniform. Since the dispersed state is realized, as a result, the strength of the molded body is improved. Furthermore, by performing melt mixing under the temperature and pressure conditions of the present invention, the affinity at the interface between the fibrous cellulose and the thermoplastic resin is improved, and the interaction force between the two is increased. Or warp does not occur.

  The cellulose-containing thermoplastic resin produced by the method for producing a cellulose-containing thermoplastic resin of the present invention is a molded product because cellulose is very uniformly dispersed in the thermoplastic resin and the affinity between the two is good. In this case, the strength characteristics are good, the distortion is not easily generated, and no discoloration or off-flavor occurs. Furthermore, even when the obtained molded product is pulverized again and remolded as a molding material, the cellulose-containing thermoplastic resin produced by the production method of the present invention hardly causes thermal deterioration of the contained cellulose. In addition, since the uniformity is maintained, the strength of the molded body is not lowered and the molded body is not discolored.

The schematic diagram of a batch type closed kneading apparatus. The schematic diagram of the rotating shaft by which the some rotating blade was arrange | positioned. The schematic diagram of the release mechanism of water vapor | steam.

  The dry defibrator used in the method for producing a cellulose-containing thermoplastic resin of the present invention is a fluffy state of cellulose aggregates such as pulp sheets and waste paper, with fluffy fibers, leaving fibers (fibers) by physical force. A device that solves the problem. As the method, a plurality of claws are arranged on the surface of the cylinder, the cylinder rotates at a high speed, and the fibers are unwound so that the claws scratch the pulp sheet surface or the like. The rotating blades rotate at high speed to strike and unravel the fibrous cellulose aggregate, and the circular discs with grooves formed on the surface are separated by a small distance so that the surfaces with grooves are opposed to each other. Various methods can be used such as disposing the fibrous cellulose aggregates rotated in the opposite directions and releasing the fibrous cellulose aggregate introduced therebetween by frictional force, and the method of fibrillation is not particularly limited.

  Examples of dry defibrators include Zuikou fibrillators, Ikegami Kikai fibrillators, Ishikawa Creativity and Development Cooperative waste paper pulverizers, West Japan Technology Development Co., Ltd. dry fibrillators, and Turbo Industries. Although the defibrator made from a corporation | Co., Ltd. can be mentioned, the dry defibrator which can be used by this invention is not restricted to these.

  The batch-type closed kneading apparatus used in the present invention specifically refers to a batch-type high-speed stirring apparatus described in International Publication No. 2004/076044 manufactured by M & F Technology Co., Ltd. FIG. 1 is a schematic view of a batch type closed kneading apparatus used in the present invention. In the batch type closed kneading apparatus 1 used in the present invention, a cylindrical stirring chamber 3 on the machine base 2 and a material supply chamber 13 in which a material charging unit 14 and a spiral blade member 12 are disposed are provided. Arranged by a plurality of legs. A rotary shaft 5 is horizontally supported by bearings 4, 4 arranged at the leg portions at both ends, and the rotary shaft 5 is coaxially inserted into the center of the stirring chamber 3.

  As shown in FIG. 2, the outer periphery of the rotating shaft 5 disposed through the stirring chamber 3 has a total of six cross-sectional rectangles and rotary blades 10 a to 10 f having an overall shape rectangle. The rotating shaft 5 is provided so as to be opposed to each other in the axial direction at an angular interval of 180 degrees in the circumferential direction. When the rotary blades 10a and 10f at both ends in the axial direction rotate clockwise when viewed from the right side of FIG. 1, the leading edges of the rotary blades 10a and 10f are the inner surfaces of the vertical walls 11 and 11 at both ends of the stirring chamber 3. It is fixed to the outer periphery of the rotating shaft 5 so as to be in sliding contact with almost no gap. Further, the four rotating blades 10b, 10c, 10d, and 10e in the middle portion are fixed in a zigzag manner on the outer peripheral surface of the rotating shaft 5, and are arranged in directions in which the leading edges during rotation face both ends of the stirring chamber 3. ing.

  The motor side of the vertical walls 11 at both ends of the stirring chamber 3 is a material supply port of the stirring chamber 3 provided in one end wall of the stirring chamber 3, and 12 is a spiral material formed on the outer periphery of the rotating shaft 5. A supply blade member, 13 is a material supply chamber surrounding the supply screw, 14 is a material input portion provided above the material supply chamber 13, and the material input portion 14 is melted and kneaded after supplying the material. An openable and closable shutter 15 is sometimes provided that can maintain hermeticity at times.

  In the batch type closed kneading apparatus used in the present invention, a water vapor release mechanism 20 is provided at both ends of the rotary shaft 5. FIG. 3 is an enlarged schematic view of the water vapor release mechanism 20. A spiral groove 22 is cut in the portion of the rotating shaft that constitutes the water vapor release mechanism, and when the rotating shaft 5 rotates, a right screw or so that air is sent from the outside into the stirring chamber, or A spiral groove 22 is cut in the direction of the left screw. In FIG. 3, an arrow 24 indicates the direction of air sent from the outside into the stirring chamber. In the present invention, since the inside of the stirring chamber 3 is in a very high pressure state at the time of melt kneading, the high-pressure steam in the stirring chamber tends to leak out in the direction of the arrow 23. However, in the water vapor release mechanism portion 20, the distance between the outermost peripheral portion of the spiral groove 22 cut in the rotating shaft 5 and the outer wall portion is very small. It comes to keep balance. Specifically, the distance between the outermost peripheral portion of the spiral groove 22 and the outer wall is 50 to 3000 μm, more preferably 50 to 700 μm, and further preferably 50 to 500 μm.

  The rotating shaft 5 on which the rotating blades are arranged is connected to a motor 8 that is a driving source. In the batch type closed kneading apparatus used in the present invention, a torque meter that measures the rotational torque applied to the motor 8 is installed. The control panel 21 can monitor the rotational torque. In the method for producing a cellulose-containing thermoplastic resin of the present invention, the change in the rotational torque of the rotary shaft 5 provided with the rotary blades 10a to 10f measured from the torque meter is measured to determine the end point of the melt-kneading. To do. Measures for the end operation according to the measured value of rotational torque are essential for materials handled for the first time, but when using the same material constantly, it is not always necessary to measure each time. It may be determined and the end point may be determined based on the determined melt-kneading time.

  In the method for producing a cellulose-containing thermoplastic resin in the present invention, the temperature and pressure conditions under which the fibrous cellulose and the thermoplastic resin are melted and mixed in the stirring chamber of the batch type closed kneader are in the temperature range of 150 to 370 ° C. 200 to 370 ° C. is more preferable, 250 to 370 ° C. is more preferable, and the pressure range is 0.20 MPa to saturated water vapor pressure at the melt kneading temperature, and saturated water vapor pressure at 2.00 to melt kneading temperature is more preferable. . In the present invention, it is more preferable that the melt kneading is carried out in a subcritical state of water having a temperature or pressure slightly lower than the temperature of 375 ° C. and a pressure of 22.00 MPa, which is a supercritical state of water.

  The saturated water vapor pressure in the present invention is calculated from the melt-kneading temperature using the tentens (1930) equation shown in Equation 1, but the melt-kneading temperature is constant during the melt-kneading, and the inside of the stirring chamber If the volume does not change, the water vapor pressure inside the stirring chamber does not exceed the saturated water vapor pressure.

T (° C.): temperature inside the stirring chamber E (T) (hPa): saturated water vapor pressure at temperature T (° C.)

  The cellulose in the present invention is not particularly limited as long as it is a fibrous cellulose obtained by defibrating a cellulose aggregate using plant cell walls as a raw material with a dry defibrator. Examples of cellulose aggregates include natural celluloses such as wood (conifers, hardwoods), cotton linters, kenaf, manila hemp (avaca), sisal hemp, jute, sabygrass, esparto grass, bagasse, rice straw, straw, straw and bamboo. Pulp, paper, and used paper as the main component are used. Pulp is a pulp obtained by a mechanical method (crushed wood pulp, refiner ground pulp, thermomechanical pulp, semi-chemical pulp, chemiground pulp, etc.), and a pulp obtained by a chemical method (craft pulp, sulfite pulp, etc.) Or the like.

  The cellulose used in the present invention is preferably fibrous cellulose obtained by defibrating chemical pulp with a dry defibrator. Chemical pulp has high color homogeneity, so the hue becomes uniform when formed into a molded product, and even when the molded product is colored by mixing a master batch or pigment during molding, the appearance of a uniform color It is possible to obtain a molded body having Chemical pulp, for example, natural cellulose such as wood (conifers, hardwoods), cotton linters, kenaf, manila hemp (avaca), sisal hemp, jute, sabygrass, esparto grass, bagasse, rice straw, straw, straw, bamboo, etc. Treated pulp (craft pulp, sulfite pulp, etc.). It is more preferable to use kraft pulp (N-BKP, L-BKP, etc.) that is chemically bleached and white in color because the whiter background is easier to adjust the color of the molded body.

  The cellulose used in the present invention may be a fiber lump (for example, cotton-like) thereafter, as long as the fibers are unwound one by one by a dry defibrator. The dimension of the fibrillated fibrous cellulose is not particularly limited, but the fiber length is preferably 0.5 to 10 mm, more preferably 1 to 8 mm, and further preferably 1 to 5 mm, from the workability during molding. The fiber diameter is preferably 10 to 100 μm, more preferably 10 to 70 μm, still more preferably 15 to 50 μm. In the dimension of the fibrillated fibrous cellulose, the aspect ratio (length / diameter) is particularly important in order to maintain the strength of the molded body. The aspect ratio of the fibrillated fibrous cellulose in the present invention is preferably 10 to 1000, more preferably 30 to 500, and still more preferably 50 to 100.

  The cellulose used in the present invention preferably has a water content of 5 to 30% by mass. When the moisture content of cellulose is in this range, the melt mixing time is shortened and the productivity is good. On the other hand, if the moisture content is less than 5% by mass, the pressure in the stirring chamber may not increase even if time is taken. In addition, even when the pressure increases and melt kneading is performed, the cellulose or inter-fiber interaction increases, and the dispersibility of the cellulose deteriorates. As a result, the fiber mass increases and the strength of the molded body decreases, May decrease. On the other hand, when the water content exceeds 30% by mass, it takes time to dehydrate the cellulose, so that the melt-kneading time becomes long and the cellulose is likely to be decomposed. The water content is more preferably 8 to 25% by mass, further preferably 10 to 20% by mass. The water content in the present invention refers to a numerical value obtained by dividing the absolute drying rate obtained by an operation method according to JIS P8203 from 100% by mass with a drying temperature of 120 ± 2 ° C.

  The procedure of the method for producing the cellulose-containing thermoplastic resin of the present invention will be described. Defibrillated fibrous cellulose is obtained from the prepared cellulose aggregate (for example, L-BKP) using a dry defibrator. Next, cellulose and a thermoplastic resin are put into a batch type closed kneading apparatus. Cellulose and the thermoplastic resin may be premixed with a blender or the like before being added, or may be sequentially added to the stirring chamber 3. When the cellulose and the thermoplastic resin are directly put into the stirring chamber 3 without premixing, it is preferable to put them while rotating the rotating blades 10a to 10f inside the stirring chamber 3 at a low speed. After the cellulose and the thermoplastic resin are put into the stirring chamber 3, the stirring chamber 3 is sealed, and the rotary blades 10a to 10f are rotated at high speed. Cellulose and the thermoplastic resin are subjected to a strong shearing force, and the temperature inside the stirring chamber 3 rises rapidly. As the temperature rises rapidly, the water contained in the cellulose evaporates and turns into water vapor, the inside of the stirring chamber 3 is filled with water vapor, and the internal pressure rises rapidly. Furthermore, when the temperature inside the stirring chamber 3 exceeds the softening temperature and melting temperature of the thermoplastic resin, the thermoplastic resin starts to soften or melt, and melt mixing with cellulose starts.

  In the method for producing a cellulose-containing thermoplastic resin of the present invention, by measuring the rotational torque of the rotary shaft 5 provided with the rotary blades 10a to 10f, the progress of the melt mixing is grasped, and the melt mixing is stopped. Can be determined. That is, the rotational torque increases as the rotational speed of the rotary blades 10a to 10f increases. However, as the temperature of the material to be kneaded increases, the thermoplastic resin starts to melt, so that the rotational torque once reached the maximum value is , It continues to decrease with the progress of thermal melting of the thermoplastic resin. At this time, melt mixing of the cellulose and the thermoplastic resin has started, and the interaction force at the interface between the cellulose and the resin increases, so that the rotational torque once shows a minimum value and then reverses and starts to rise again. . In the present invention, the rotation of the rotary shaft 5 may be stopped immediately after the rotational torque starts to rise again. In the present invention, the temperature in the stirring chamber 3 continues to rise while the rotational torque fluctuates in the order of increase → decrease → rise. It is preferable to stop before reaching.

  At the time of melt mixing, the material to be kneaded made of cellulose and a thermoplastic resin needs to be protected from oxidative decomposition. In particular, suppression of oxidation by oxygen is important for suppressing changes in the structural properties of the material to be kneaded. Therefore, in the method for producing a cellulose-containing thermoplastic resin of the present invention, in the water vapor release mechanism, the water vapor inflow / outflow balance is maintained, that is, the water flowing out from the stirring chamber and the water flowing from the outside into the stirring chamber. It is preferable to prevent the inflow of air into the stirring chamber by maintaining a balanced equilibrium state with the air to be released. In the production method of the present invention, immediately after the start of kneading, the pressure in the stirring chamber rises rapidly, and at that time, the inflow / outflow of water vapor is not in a balanced state in the water vapor release mechanism, The water vapor flows out from the release mechanism. During this time, the pressure in the stirring chamber shows a decreasing tendency, finally reaches an equilibrium state, and maintains a constant pressure. In the production method of the present invention, the inside of the stirring chamber may be in a subcritical state of water. The subcritical state of water means a state lower than the supercritical point of water (temperature: 375 ° C., pressure: 22.00 MPa), and subcritical water is very oxidizable. Since cellulose is slowly decomposed by a hydration reaction even in the subcritical state of water at 300 ° C. and around 20.00 MPa, the reaction time is also important. In consideration of the above, in the manufacturing method of the present invention, with the pressure of the stirring chamber maintained, immediately after the rotational torque exhibits the minimum value, that is, from at least 1 second after the minimum value is exhibited. Melting and mixing for 10 minutes, more preferably 1 to 2 minutes, and even more preferably 1 to 30 seconds, preventing inflow of oxygen and protecting cellulose and thermoplastic resin from decomposition by oxygen oxidation or hydration Is preferred. Further, due to the problem of the strength of the apparatus, when the pressure in the stirring chamber is higher than around 23.00 MPa, there is a high probability that the stirring chamber itself may be damaged because it cannot withstand a sudden pressure increase. Although it is sufficient to increase the strength of the apparatus, the cost for that is very expensive, which is not economical.

  The thermoplastic resin in the present invention is a resin that can be softened by heating to a glass transition temperature or a melting point, and can be molded into a desired shape. For example, polyethylene composed of high-density polyethylene, medium-density polyethylene, and low-density polyethylene. Polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl acetate, polytetrafluoroethylene, acrylonitrile butadiene styrene resin, acrylonitrile styrene copolymer resin, acrylic resin, polyethylene terephthalate, polymethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate Examples thereof include polyester resins composed of phthalate, polybutylene naphthalate, and the like, but are not particularly limited as long as they are thermoplastic resins. Preferably, polyolefins such as polyethylene and polypropylene are used.

  Furthermore, a biodegradable resin can also be used as the thermoplastic resin. By using a biodegradable resin, it is expected that the molded product is decomposed by burying the molded product in the soil or the like at the time of disposal. The biodegradable resin is not particularly limited as long as it is an environmentally decomposed resin, particularly a resin that is decomposed by the action of microorganisms. For example, specific examples include polymeric polysaccharides, microbial polyesters, aliphatic polyesters, and more specifically, polylactic acid resin, polycaprolactone resin, polybutylene succinate adipate resin, polyethylene succinate resin, polyethylene. Succinate carbonate resin, polybutylene succinate resin, polybutylene adipate terephthalate resin, polyhydroxyalkanoate (eg, poly (3-hydroxybutyric acid) (PHB), poly (3-hydroxyvaleric acid) (PHV)), lactone resin And polyester resins obtained from low molecular weight aliphatic dicarboxylic acids and low molecular weight aliphatic diols, cellulose acetate-based composites, modified starch-modified polyvinyl alcohol composites, and other composites.

  When a biodegradable resin is used as the thermoplastic resin of the present invention, it is preferable to use a polylactic acid resin because of its versatility. The polylactic acid resin includes a lactic acid-based polymer such as a lactic acid copolymer and a blend polymer in addition to a polylactic acid homopolymer. The mass average molecular weight of the lactic acid polymer is generally 5 to 500,000. Further, the constituent molar ratio L / D of the L-lactic acid unit and the D-lactic acid unit in the polylactic acid resin may be any of 100/0 to 0/100, and is not particularly limited.

  In the present invention, the mass ratio of cellulose and thermoplastic resin is preferably 10/90 to 70/30. When the mass ratio is within this range, the dispersion state of cellulose in the thermoplastic resin becomes more uniform, the direction of cellulose dispersed in the molded body becomes more random, and anisotropy in the molded body does not occur. . In addition, when the mass ratio of fibrous cellulose and thermoplastic resin is within this range, the amount of combustion heat generated when the molded product made of the cellulose-containing thermoplastic resin of the present invention is incinerated can be reduced. The mass ratio is more preferably 20/80 to 60/40, further preferably 40/60 to 60/40.

  In the present invention, various additives can be appropriately added in addition to cellulose and the thermoplastic resin. Additives include compatibilizers, antioxidants, heat stabilizers, lubricants, mold release agents, plasticizers, UV absorbers, light stabilizers, pigments, dyes, antistatic agents, conductivity-imparting agents, dispersants, Additives such as transparent nucleating agents, antibacterial agents, antifungal agents, and flame retardants can be used alone or in combination of two or more, but are not limited thereto. In particular, it is preferable to add an organic antioxidant, an organic ultraviolet absorber, an antistatic agent, and a flame retardant because the use of the cellulose-containing thermoplastic resin of the present invention is expanded. Examples of organic antioxidants include phenolic, hindered phenolic, thioether and phosphite types.

  Addition of an acid-modified polyolefin resin is preferable because the affinity between cellulose and the thermoplastic resin can be further improved and the adhesiveness between the two can be strengthened. The acid-modified polyolefin resin refers to one obtained by modifying a polyethylene resin or a polypropylene resin with one or a mixture of two or more of unsaturated carboxylic acids and derivatives (monomers) thereof. Examples of unsaturated carboxylic acids and derivatives thereof include unsaturated carboxylic acids such as acrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, and derivatives thereof, such as, specifically, anhydrides, amides, imides, esters Etc. Among these, maleic anhydride-modified polyolefin is particularly preferable. The amount of maleic anhydride-modified polyolefin added to the cellulose-containing thermoplastic resin is preferably from 0.1 to 10% by mass, more preferably from 1 to 7% by mass, and more preferably from 2 to 5% by mass, based on the content of the cellulose-containing thermoplastic resin. Is more preferable.

  Using the cellulose-containing thermoplastic resin of the present invention, a molded product can be produced by various molding methods. As a molding method, a general molding method can be used and is not particularly limited. Examples include injection molding, extrusion molding, compression molding, rotational molding, hollow molding (blow molding), T-die molding, inflation molding, calendar molding, and the like. There is no limit to the method. Further, the shape of the molded body is not particularly limited, and any shape may be produced by any molding method.

  EXAMPLES Next, although an Example demonstrates this invention still in detail, this invention is not limited to these at all.

Example 1
As a cellulose aggregate, a hardwood bleached kraft pulp (L-BKP) pulp sheet was prepared, and coarsely pulverized with a Horai pulverizer (trade name: BO-2572, equipped with a 30 mm screen). Next, the coarsely pulverized material was put into a defibrating machine (trade name: Turbo Mill T-250) manufactured by Turbo Industry Co., Ltd., and the pulp sheet was defibrated to obtain cellulose in the present invention. The water content of the cellulose was 18% by mass. Cellulose / thermoplastic resin (manufactured by Prime Polymer Co., Ltd., trade name: Prime Polypro (registered trademark) F109V) / maleic anhydride modified polypropylene (Mitsubishi Chemical Corporation, trade name: Modic (registered trademark) P928) = 50 / 45/5 (mass ratio) was prepared, premixed, and then charged into a stirring chamber of a batch type closed kneading apparatus (manufactured by M & F Technology, Inc.). Thereafter, the rotating blades were rotated at a rotational speed of 2700 rpm. At the same time as the rotation started, water vapor leaked from the water vapor release mechanism, but after 30 seconds, the leakage stopped, and melt mixing proceeded in a state where the water vapor was released in a balanced state. 30 seconds after the water vapor leak stops, the motor torque reaches the maximum value, then starts to decrease, and after 3 seconds after the minimum value starts to rise, the motor is switched off and the rotating blades Stopped rotating. It should be noted that the temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the leakage of water vapor stopped until the rotation of the rotary blade stopped.

(Example 2)
Example 1 except that the water vapor release mechanism was adjusted so that the temperature in the stirring chamber after the water vapor leakage stopped until the rotation of the rotating blades stopped was 250 ° C., and the pressure was 0.20 MPa. In the same manner as above, the cellulose-containing thermoplastic resin of the present invention was obtained.

(Example 3)
The steam release mechanism is set so that the temperature in the stirring chamber from the stop of the leakage of steam until the stop of the rotation of the rotating blades is 250 ° C., and the pressure is a saturated steam pressure of 4.30 MPa at 250 ° C. A cellulose-containing thermoplastic resin of the present invention was obtained in the same manner as in Example 1 except for adjusting.

Example 4
The rotation speed of the rotary blade is changed to 2000 rpm, and the water vapor release mechanism is adjusted, and the temperature in the stirring chamber after the water vapor leakage stops until the rotary blade stops rotating shows 150 ° C. The cellulose-containing thermoplastic resin of the present invention was obtained in the same manner as in Example 1 except that the pressure was 0.20 MPa.

(Example 5)
Example 4 except that the water vapor release mechanism was adjusted so that the temperature in the stirring chamber after the water vapor leakage stopped until the rotation of the rotary blade stopped was 150 ° C., and the pressure was 0.30 MPa. In the same manner as above, the cellulose-containing thermoplastic resin of the present invention was obtained.

(Example 6)
The steam release mechanism is set so that the temperature in the stirring chamber after the steam leakage stops and the rotation of the rotating blades stops is 150 ° C., and the pressure is a saturated steam pressure at 150 ° C. of 0.49 MPa. A cellulose-containing thermoplastic resin of the present invention was obtained in the same manner as in Example 4 except for adjusting.

(Example 7)
The rotation speed of the rotating blades was changed to 3800 rpm, and the water vapor release mechanism was adjusted so that the temperature in the stirring chamber after the water vapor leakage stopped until the rotation of the rotating blades stopped showed 370 ° C. The cellulose-containing thermoplastic resin of the present invention was obtained in the same manner as in Example 1 except that the pressure was 0.20 MPa.

(Example 8)
Example 7 except that the water vapor release mechanism was adjusted so that the temperature in the stirring chamber after the water vapor leakage stopped until the rotation of the rotating blades stopped was 370 ° C., and the pressure was 11.00 MPa. In the same manner as above, the cellulose-containing thermoplastic resin of the present invention was obtained.

Example 9
Example 7 except that the water vapor release mechanism was adjusted so that the temperature in the stirring chamber after the water vapor leakage stopped until the rotation of the rotating blades stopped was 370 ° C., and the pressure was 21.00 MPa. In the same manner as above, the cellulose-containing thermoplastic resin of the present invention was obtained. This temperature and pressure condition corresponds to the subcritical state of water.

(Example 10)
The steam release mechanism so that the temperature in the stirring chamber after the stoppage of the steam leakage until the stop of the rotation of the rotating blades is 370 ° C., and the pressure is 22.60 MPa which is the saturated steam pressure at 370 ° C. The cellulose-containing thermoplastic resin of the present invention was obtained in the same manner as in Example 7 except that the parts were adjusted.

(Example 11)
The present invention was carried out in the same manner as in Example 1 except that the cellulose aggregate was changed to a pulp sheet of softwood bleached kraft pulp (N-BKP), and the moisture content of cellulose obtained by defibration was 18% by mass. Of cellulose-containing thermoplastic resin was obtained. The temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the leakage of water vapor stopped until the rotation of the rotary blade stopped.

(Example 12)
The present invention was carried out in the same manner as in Example 9 except that the cellulose aggregate was changed to a pulp sheet of softwood bleached kraft pulp (N-BKP), and the moisture content of cellulose obtained by defibration was 18% by mass. Of cellulose-containing thermoplastic resin was obtained. The temperature in the stirring chamber was 370 ° C. and the pressure was 21.00 MPa after the water vapor leakage stopped until the rotation of the rotary blade stopped. This temperature and pressure condition corresponds to the subcritical state of water.

(Example 13)
The cellulose aggregate was changed to a hardwood chemical ground pulp (CGP) pulp sheet, and the moisture content of cellulose obtained by defibration was 18% by mass. A cellulose-containing thermoplastic resin was obtained. The temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the leakage of water vapor stopped until the rotation of the rotary blade stopped.

(Example 14)
The cellulose aggregate was changed to a hardwood chemical ground pulp (CGP) pulp sheet, and the moisture content of cellulose obtained by defibration was 18% by mass. A cellulose-containing thermoplastic resin was obtained. The temperature in the stirring chamber was 370 ° C. and the pressure was 21.00 MPa after the water vapor leakage stopped until the rotation of the rotary blade stopped. This temperature and pressure condition corresponds to the subcritical state of water.

(Example 15)
The present invention was carried out in the same manner as in Example 1 except that the cellulose aggregate was changed to a hardwood bleached kraft pulp (L-BKP) pulp sheet, and the moisture content of cellulose obtained by defibration was 3% by mass. Of cellulose-containing thermoplastic resin was obtained. Since the water vapor release mechanism was adjusted so that the pressure was 2.00 MPa, the temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the water vapor leakage stopped until the rotation of the rotating blades stopped. Was showing.

(Example 16)
The present invention was carried out in the same manner as in Example 1 except that the cellulose aggregate was changed to a hardwood bleached kraft pulp (L-BKP) pulp sheet and the moisture content of cellulose obtained by defibration was 5% by mass. Of cellulose-containing thermoplastic resin was obtained. Since the water vapor release mechanism was adjusted so that the pressure was 2.00 MPa, the temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the water vapor leakage stopped until the rotation of the rotating blades stopped. Was showing.

(Example 17)
The present invention was carried out in the same manner as in Example 1 except that the cellulose aggregate was changed to a hardwood bleached kraft pulp (L-BKP) pulp sheet and the moisture content of cellulose obtained by defibration was 8% by mass. Of cellulose-containing thermoplastic resin was obtained. Since the water vapor release mechanism was adjusted so that the pressure was 2.00 MPa, the temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the water vapor leakage stopped until the rotation of the rotating blades stopped. Was showing.

(Example 18)
The present invention was carried out in the same manner as in Example 1 except that the cellulose aggregate was changed to a hardwood bleached kraft pulp (L-BKP) pulp sheet, and the moisture content of cellulose obtained by defibration was 10% by mass. Of cellulose-containing thermoplastic resin was obtained. Since the water vapor release mechanism was adjusted so that the pressure was 2.00 MPa, the temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the water vapor leakage stopped until the rotation of the rotating blades stopped. Was showing.

(Example 19)
The present invention was carried out in the same manner as in Example 1 except that the cellulose aggregate was changed to a pulp sheet of softwood bleached kraft pulp (N-BKP), and the moisture content of cellulose obtained by defibration was 20% by mass. Of cellulose-containing thermoplastic resin was obtained. Since the water vapor release mechanism was adjusted so that the pressure was 2.00 MPa, the temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the water vapor leakage stopped until the rotation of the rotating blades stopped. Was showing.

(Example 20)
The present invention was carried out in the same manner as in Example 1 except that the cellulose aggregate was changed to a hardwood bleached kraft pulp (L-BKP) pulp sheet and the moisture content of cellulose obtained by defibration was 25% by mass. Of cellulose-containing thermoplastic resin was obtained. Since the water vapor release mechanism was adjusted so that the pressure was 2.00 MPa, the temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the water vapor leakage stopped until the rotation of the rotating blades stopped. Was showing.

(Example 21)
The present invention was carried out in the same manner as in Example 1 except that the cellulose aggregate was changed to a hardwood bleached kraft pulp (L-BKP) pulp sheet and the moisture content of cellulose obtained by defibration was 30% by mass. Of cellulose-containing thermoplastic resin was obtained. Since the water vapor release mechanism was adjusted so that the pressure was 2.00 MPa, the temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the water vapor leakage stopped until the rotation of the rotating blades stopped. Was showing.

(Example 22)
The present invention was performed in the same manner as in Example 1 except that the cellulose aggregate was changed to a hardwood bleached kraft pulp (L-BKP) pulp sheet and the moisture content of cellulose obtained by defibration was 35% by mass. Of cellulose-containing thermoplastic resin was obtained. Since the water vapor release mechanism was adjusted so that the pressure was 2.00 MPa, the temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the water vapor leakage stopped until the rotation of the rotating blades stopped. Was showing.

(Example 23)
Cellulose / thermoplastic resin / maleic anhydride modified polypropylene = 8/87/5 (mass ratio), and the same procedure as in Example 1 except that the water vapor release mechanism was adjusted so that the pressure was 2.00 MPa. The cellulose-containing thermoplastic resin of the invention was obtained. The temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the leakage of water vapor stopped until the rotation of the rotary blade stopped.

(Example 24)
Cellulose / thermoplastic resin / maleic anhydride modified polypropylene = 10/85/5 (mass ratio) and the same procedure as in Example 1 except that the water vapor release mechanism was adjusted so that the pressure was 2.00 MPa. The cellulose-containing thermoplastic resin of the invention was obtained. The temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the leakage of water vapor stopped until the rotation of the rotary blade stopped.

(Example 25)
Cellulose / thermoplastic resin / maleic anhydride modified polypropylene = 20/75/5 (mass ratio) and the same procedure as in Example 1 except that the water vapor release mechanism was adjusted so that the pressure was 2.00 MPa. The cellulose-containing thermoplastic resin of the invention was obtained. The temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the leakage of water vapor stopped until the rotation of the rotary blade stopped.

(Example 26)
Cellulose / thermoplastic resin / maleic anhydride modified polypropylene = 60/35/5 (mass ratio) and the same procedure as in Example 1 except that the water vapor release mechanism was adjusted so that the pressure was 2.00 MPa. The cellulose-containing thermoplastic resin of the invention was obtained. The temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the leakage of water vapor stopped until the rotation of the rotary blade stopped.

(Example 27)
Cellulose / thermoplastic resin / maleic anhydride modified polypropylene = 70/25/5 (mass ratio) and the same procedure as in Example 1 except that the water vapor release mechanism was adjusted so that the pressure was 2.00 MPa. The cellulose-containing thermoplastic resin of the invention was obtained. The temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the leakage of water vapor stopped until the rotation of the rotary blade stopped.

(Example 28)
Cellulose / thermoplastic resin / maleic anhydride modified polypropylene = 77/18/5 (mass ratio) and the same procedure as in Example 1 except that the water vapor release mechanism was adjusted so that the pressure was 2.00 MPa. The cellulose-containing thermoplastic resin of the invention was obtained. The temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the leakage of water vapor stopped until the rotation of the rotary blade stopped.

(Example 29)
Cellulose / thermoplastic resin / maleic anhydride modified polypropylene = 85/10/5 (mass ratio) and the same procedure as in Example 1 except that the water vapor release mechanism was adjusted so that the pressure was 2.00 MPa. The cellulose-containing thermoplastic resin of the invention was obtained. The temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the leakage of water vapor stopped until the rotation of the rotary blade stopped.

(Example 30)
The rotational torque value of the motor starts to decrease after reaching the maximum value, and after 1 second from the start of the minimum value and the increase, the motor is switched off and the rotation of the rotating blades is stopped. Similarly, the cellulose-containing thermoplastic resin of the present invention was obtained. The temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the leakage of water vapor stopped until the rotation of the rotary blade stopped.

(Example 31)
After the rotational torque value of the motor reached the maximum value, it began to decrease, and after 30 seconds after showing the minimum value and starting to increase, the motor was switched off and the rotation of the rotating blades was stopped. Similarly, the cellulose-containing thermoplastic resin of the present invention was obtained. The temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the leakage of water vapor stopped until the rotation of the rotary blade stopped.

(Example 32)
The cellulose aggregate was changed to a hardwood chemical ground pulp (CGP) pulp sheet, and the moisture content of cellulose obtained by defibration was 18% by mass, and the rotational torque value of the motor was maximized 30 seconds after reaching the minimum value and starting to rise, the cellulose-containing heat of the present invention was obtained in the same manner as in Example 28 except that the motor was switched off and the rotation of the rotating blades was stopped. A plastic resin was obtained. The temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the leakage of water vapor stopped until the rotation of the rotary blade stopped.

(Example 33)
The present invention was carried out in the same manner as in Example 32 except that the cellulose aggregate was changed to a hardwood bleached kraft pulp (L-BKP) pulp sheet and the moisture content of cellulose obtained by defibration was 35% by mass. Of cellulose-containing thermoplastic resin was obtained. Since the water vapor release mechanism was adjusted so that the pressure was 2.00 MPa, the temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the water vapor leakage stopped until the rotation of the rotating blades stopped. Was showing.

(Example 34)
The cellulose aggregate was changed to a hardwood chemical ground pulp (CGP) pulp sheet, and the moisture content of cellulose obtained by defibration was 18% by mass, and the rotational torque value of the motor was maximized 3 seconds after reaching the minimum value and starting to rise, the cellulose-containing heat of the present invention was used in the same manner as in Example 28 except that the motor was switched off and the rotation of the rotating blades was stopped. A plastic resin was obtained. The temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the leakage of water vapor stopped until the rotation of the rotary blade stopped.

(Example 35)
The cellulose aggregate was changed to a hardwood chemical ground pulp (CGP) pulp sheet, and the moisture content of cellulose obtained by defibration was 35% by mass. A cellulose-containing thermoplastic resin was obtained. Since the water vapor release mechanism was adjusted so that the pressure was 2.00 MPa, the temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the water vapor leakage stopped until the rotation of the rotating blades stopped. Was showing.

(Example 36)
The cellulose aggregate was changed to a hardwood chemical ground pulp (CGP) pulp sheet, and the moisture content of cellulose obtained by defibration was 18% by mass, and the formulation was cellulose / thermoplastic resin = 50 / A cellulose-containing thermoplastic resin of the present invention was obtained in the same manner as in Example 31, except that the ratio was 50 (mass ratio). Since the water vapor release mechanism was adjusted so that the pressure was 2.00 MPa, the temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the water vapor leakage stopped until the rotation of the rotating blades stopped. Was showing.

(Example 37)
The rotation speed of the rotary blade is changed to 3800 rpm, and further, the temperature in the stirring chamber from the stop of the leakage of water vapor to the stop of the rotation of the rotary blade is 370 ° C., and the pressure is 21.00 MPa. A cellulose-containing thermoplastic resin of the present invention was obtained in the same manner as in Example 36 except that the water vapor release mechanism was adjusted. This temperature and pressure condition corresponds to the subcritical state of water.

(Comparative Example 1)
Prepare a pulp sheet of hardwood kraft pulp (L-BKP) as a cellulose aggregate and pulverize it with a cutter-type crusher (trade name: BO-2572 2 mm mesh installed by Horai Co., Ltd.) to prepare tabular cellulose did. In addition, the moisture content of the obtained flat cellulose was 18 mass%. A cellulose-containing thermoplastic resin was obtained in the same manner as in Example 1 except that the fibrous cellulose was changed to tabular cellulose. Note that the water vapor release mechanism was adjusted so that the pressure in the stirring chamber was 2.00 MPa. The temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the leakage of water vapor stopped until the rotation of the rotary blade stopped.

(Comparative Example 2)
A Henschel mixer (registered trademark, manufactured by Mitsui Mining Co., Ltd.), a batch kneading device, is heated to 140 ° C., and a hardwood kraft pulp (L-BKP) pulp sheet is added as a cellulose aggregate to obtain an average peripheral speed. When stirred at 50 m / sec, cotton-like cellulose was formed 2 minutes after the start of stirring. Subsequently, after a thermoplastic resin (manufactured by Prime Polymer Co., Ltd., trade name: Prime Polypro (registered trademark) F109V) was charged into the mixer, stirring was continued at an average peripheral speed of 50 m / sec. The power of the motor at this time was 2.5 kW, and the temperature in the mixer was 120 ° C. Ten minutes after the thermoplastic resin was added, the power started to increase, and one minute later, the power increased to 4 kW, so the peripheral speed was reduced to a low speed of 25 m / sec. Furthermore, the power started to increase due to the continued low-speed stirring, and the power reached 5 kW. Therefore, the outlet of the mixer was opened and the Henschel mixer (registered trademark, manufactured by Mitsui Mining Co., Ltd.) was prepared separately. ). Thereafter, stirring of the mixer at room temperature was started at an average peripheral speed of 10 m / sec. When the temperature in the mixer reached 80 ° C., stirring was stopped, and the cellulose-containing thermoplastic resin was taken out. The taken out cellulose-containing thermoplastic resin was a granulated product having a diameter of several mm to 2 cm. In addition, since the mixer is not completely sealed, the pressure at the time of stirring is a normal pressure (0.10 MPa).

(Comparative Example 3)
The same procedure as in Example 1 was performed except that wet cellulose defibrated cellulose (manufactured by Daicel Chemical Industries, Ltd., trade name: Celish (registered trademark) PC-110T, water content 65 mass%) was used. A cellulose-containing thermoplastic resin was obtained. Note that the water vapor release mechanism was adjusted so that the pressure in the stirring chamber was 2.00 MPa. The temperature in the stirring chamber was 250 ° C. and the pressure was 2.00 MPa from the time when the leakage of water vapor stopped until the rotation of the rotary blade stopped.

(Comparative Example 4)
By adjusting the rotation speed of the rotating blades to 1700 rpm and adjusting the water vapor release mechanism, the temperature in the stirring chamber from the time when the leakage of water vapor stops until the rotation of the rotating blades stops is 140 ° C. and the pressure is increased. A cellulose-containing thermoplastic resin was obtained in the same manner as in Example 1 except that the pressure was 0.20 MPa.

(Comparative Example 5)
By adjusting the rotation speed of the rotary blades to 2000 rpm and adjusting the water vapor release mechanism, the temperature in the stirring chamber from the time when the leakage of water vapor stops until the rotation of the rotary blades stops is 150 ° C. and the pressure is A cellulose-containing thermoplastic resin was obtained in the same manner as in Example 1 except that the pressure was 0.18 MPa.

(Comparative Example 6)
By adjusting the rotation speed of the rotating blades to 4000 rpm and further adjusting the water vapor release mechanism, the temperature in the stirring chamber from the time when the leakage of water vapor stops until the rotation of the rotating blades stops is 410 ° C., and the pressure is increased. A cellulose-containing thermoplastic resin was obtained in the same manner as in Example 1 except that the pressure was 0.20 MPa.

(Comparative Example 7)
After the rotational torque showed the maximum value, a cellulose-containing thermoplastic resin was obtained in the same manner as in Example 1 except that the melt mixing was terminated immediately before it started to decrease and reached the minimum value.

(Comparative Example 8)
A cellulose-containing thermoplastic resin was obtained in the same manner as in Example 1 except that the melt mixing was terminated 20 minutes after the rotational torque showed the minimum value.

(Comparative Example 9)
A cellulose-containing thermoplastic resin was obtained in the same manner as in Example 1 except that the melt mixing was terminated when the rotational torque began to decrease after reaching the maximum value.

(Comparative Example 10)
A cellulose-containing thermoplastic resin was obtained in the same manner as in Example 1, except that the rotational torque started to decrease after reaching the maximum value and melt mixing was terminated when the rotational torque reached 50% of the maximum value.

(warp)
A plate (150 mm × 80 mm × 1 mm) was injection molded using an injection molding machine (manufactured by Nippon Steel Works, Ltd., trade name: J55ELIII) using the cellulose-containing thermoplastic resin produced in the examples and comparative examples. During molding, the injection time was set to 0.3 seconds. The prepared plate was placed on a flat table and the lift amount was measured. In the measurement, when one of the four corners was brought into close contact with the table, the amount of lifting at the corner having the highest lifting amount was measured. It is considered that the smaller the amount of lift, the better the resin characteristics, because the more uniform the dispersibility of cellulose in the thermoplastic resin is, the less the warpage of the molded product is.

(Flexural modulus)
The bending elastic modulus was measured according to JIS K7171 using the cellulose-containing thermoplastic resins prepared in Examples and Comparative Examples. However, the number of test pieces was set to 20, the measurement was performed 20 times, and the average value was taken as the flexural modulus. The larger the value, the higher the flexural modulus and the better. In addition, the test piece was cut out from the multipurpose test piece A form produced according to JISK7139.

(Variation in flexural modulus)
The standard deviation was calculated from the measurement results of the bending elastic modulus at 20 points and used as a measure of the variation in bending elastic modulus. The smaller the standard deviation, the smaller the variation and the better the uniformity. The high degree of uniformity reflects the high degree of uniformity of cellulose dispersion in the thermoplastic resin.

(Anisotropy of flexural modulus)
A plate (150 mm × 80 mm × 4 mm) was injection molded with an injection molding machine (manufactured by Nippon Steel Works, Ltd., trade name: J55ELIII) using the cellulose-containing thermoplastic resin prepared in Examples and Comparative Examples. During molding, the injection time was set to 0.3 seconds. A test piece for measuring the flexural modulus was cut out from the produced plate. The test piece cut out so that the long side (150 mm) and the short side (80 mm) are each in two directions, and the test piece cut out so that the length direction of the test piece and the long side of the plate are parallel is the LP piece, the test A test piece cut out so that the width direction of the piece and the short side of the plate were parallel was defined as a WP piece. For each of the five test pieces, the bending elastic modulus was measured in accordance with JIS K7171, and the average value was used as the elastic modulus in each direction. (LP bending elastic modulus) / (WP bending elastic modulus) Is the anisotropy of the flexural modulus. As the anisotropy of the flexural modulus is closer to 1, the anisotropy is smaller and better. It is judged that the smaller the anisotropy of the flexural modulus is, the higher the uniformity of cellulose dispersion in the thermoplastic resin is.

(Color of molded product)
Test for evaluation by injection molding a plate (150 mm × 80 mm × 4 mm) with an injection molding machine (trade name: J55ELIII, manufactured by Nippon Steel Works, Ltd.) using the cellulose-containing thermoplastic resin prepared in Examples and Comparative Examples It was a piece. During molding, the injection time was set to 0.3 seconds. Ten test pieces were prepared, and the coloration was observed visually. The test piece color is milky white and no burnt brown part is seen at all, ◯, the whole is slightly brown, or the part is partially browned △, clearly What burnt brown was evaluated as x.

(Smell of molded product)
An evaluation was made by smelling the 10 test pieces prepared in the evaluation of the color of the molded article. A sample having no burnt odor was rated as ◯, and a sample having a slight burnt odor was rated as ×.

(Appearance of molded body (foreign matter))
In the test piece produced by evaluation of the color of the molded body, the number of foreign matters having an area of 1 mm ² or more present on one surface was visually counted. Ten test pieces were evaluated, and the average value was evaluated as the appearance (foreign matter) of the moldability. Smaller numbers are better.

(Colorability of molded product)
10 parts by mass of blue polyolefin masterbatch (manufactured by Dainichi Seika Kogyo Co., Ltd., trade name: Die Color Master) is mixed with a blender with 90 parts by mass of the cellulose-containing thermoplastic resin produced in Examples and Comparative Examples. Then, a plate (150 mm × 80 mm × 4 mm) was injection-molded with an injection molding machine (trade name: J55ELIII, manufactured by Nippon Steel Works, Ltd.) to obtain a test piece for evaluation. Ten test pieces were prepared and visually evaluated for coloring. Those that are uniformly colored in dark blue are ◎, those that are almost uniformly colored, but some that are slightly shaded are ◯, those that are evenly colored are seen as △, blue The case where the color of brown was darker than that of blue and could not be determined whether it was colored blue was rated as x. Those judged as 実 用 and ○ have no practical problem.

(Reformability)
A plate (150 mm × 80 mm × 4 mm) was produced by injection molding using an injection molding machine (trade name: J55ELIII, manufactured by Nippon Steel Works, Ltd.) using the cellulose-containing thermoplastic resin produced in Examples and Comparative Examples. During molding, the injection time was set to 0.3 seconds. The produced plate was pulverized with a pulverizer (trade name: P1314, manufactured by Horai Co., Ltd.), and a plate (150 mm × 80 mm × 4 mm) was again injection molded under the same conditions. Using the prepared plate again, the color of the molded body and the flexural modulus were evaluated. It is judged that the remoldability is so good that these evaluation results are not different from the evaluation results of the first injection-molded plate.

  The evaluation results are shown in Tables 1 to 4.

  As shown in Tables 1 and 2, the evaluation results of warpage, variation in flexural modulus, and anisotropy of flexural modulus of the examples are superior to those of the comparative example, so the cellulose-containing thermoplastic resin of the present invention. It can be seen that the cellulose-containing thermoplastic resin produced by the production method and the molded body thereof have very high uniformity of cellulose dispersion in the thermoplastic resin. In particular, if the mass ratio of the fibrous cellulose and the thermoplastic resin is in the range of 10/90 to 70/30, the affinity at the interface between the two may be improved, or the distortion of the molded body will be reduced, and the warpage will be little. It can be seen that the anisotropy of the flexural modulus disappears. Further, in Example 22 where the moisture content is 3%, the flexural modulus is slightly lower than that of 5 to 30% by mass, and Examples 22, 32 and 33 where the moisture content is 35%. 35, since the warpage of the molded product is slightly higher, when the water content is outside the range of 5 to 30% by mass, the dispersion uniformity of cellulose in the thermoplastic resin is slightly reduced. For this reason, the warping of the molded body may be slightly larger. From this, it is understood that the water content of cellulose is more preferably 5 to 30% by mass. In addition, the value of the flexural modulus itself is significantly higher than that of the comparative example, indicating that the present invention is superior.

  Furthermore, it can be seen that the cellulose-containing thermoplastic resin of the present invention produced in a subcritical state of water has particularly small variations in flexural modulus and small anisotropy in flexural modulus.

  It can be seen that the molded body made of the cellulose-containing thermoplastic resin produced by using the production method of the present invention is excellent in the color, odor, appearance (foreign matter) and colorability of the molded body. Among these, it is understood that the color is better when the cellulose is chemical pulp. In particular, the smell of burnt cellulose does not occur in the molded product because the affinity between cellulose and the thermoplastic resin in the present invention is very good. On the other hand, it can be seen from the results of Comparative Examples 7 to 10 that the melt mixing is not stopped immediately after the rotational torque of the rotating shaft reaches the minimum value and starts to increase, so that the color of the molded body is particularly different.

  When the evaluation results of the bending elastic modulus shown in Table 3 and the evaluation results of the bending elastic modulus shown in Table 1 were compared in the examples, there was almost no difference between the two, so that the cellulose-containing thermoplastic resin production method of the present invention was used. It turns out that quality degradation hardly occurs even if a molded body made of a cellulose-containing resin is reground and used again as a molding material to produce a molded body. Moreover, even if it is reshaped, the cellulose is not burnt by reheating and the molded product is not colored. On the other hand, in the comparative example, the decrease in the flexural modulus and the deterioration in the color of the molded product are obvious.

DESCRIPTION OF SYMBOLS 1 Batch type closed kneading apparatus 2 Machine base 3 Stirring chamber 4 Bearing 5 Rotating shaft 8 Motor 10a-10f Rotating blade 11 Vertical wall 12 of stirring chamber Spiral blade member 13 Material supply chamber 14 Material input part 15 Shutter 20 Water vapor | steam Release mechanism 21 Control panel 22 Spiral groove 23 Water vapor outflow direction 24 Air inflow direction

Claims (6)

  In a method for producing a cellulose-containing thermoplastic resin, in which a thermoplastic resin and cellulose are melt-mixed in a batch-type closed kneader having a stirring chamber provided with a rotating shaft provided with a rotary blade, Fibrous cellulose defibrated by a fiber machine, the temperature in the stirring chamber at the time of melt mixing is 150 to 370 ° C., the pressure in the stirring chamber is 0.20 MPa or more up to the saturated water vapor pressure, and A method for producing a cellulose-containing thermoplastic resin, characterized in that melt mixing is stopped immediately after the rotational torque of the rotating shaft reaches a minimum value and starts to increase.   The method for producing a cellulose-containing thermoplastic resin according to claim 1, wherein the cellulose is fibrous cellulose obtained by defibrating chemical pulp with a dry defibrating machine.   The method for producing a cellulose-containing thermoplastic resin according to claim 1 or 2, wherein the cellulose has a moisture content of 5 to 30% by mass.   The method for producing a cellulose-containing thermoplastic resin according to claim 1, wherein a mass ratio of the cellulose and the thermoplastic resin is 10/90 to 70/30.   A cellulose-containing thermoplastic resin produced by the method for producing a cellulose-containing thermoplastic resin according to claim 1.   A molded article comprising the cellulose-containing thermoplastic resin according to claim 5.

Images