JP5053117B2 - Method for producing cellulose fiber-containing thermoplastic resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a cellulose fiber-containing thermoplastic resin composition containing a mixture of a fibrillated cellulose fiber and a thermoplastic resin. <P>SOLUTION: The method for producing a cellulose fiber-containing thermoplastic resin composition comprises a process to obtain from a cellulose fiber aggregate and a thermoplastic resin a mixture comprised of the fibrillated cellulose fiber adhered with the thermoplastic resin, and a process to melt-knead the mixture in an extruder, to filter through a mesh-part of 60-200 mesh (JIS Z8801 and ISO 3310), and to extrude. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a method for producing a cellulose fiber-containing thermoplastic resin composition and a resin molded article comprising the composition obtained by the method.

  In order to increase the mechanical strength of the resin molded body, those containing inorganic fibers such as glass fibers are widely used (Patent Documents 1 to 4). However, a resin molded body in which inorganic fibers are blended generates a residue derived from inorganic fibers during incineration, and this residue needs to be landfilled. Therefore, a resin molded body that does not use inorganic fibers is required. Yes.

Patent Document 5 describes a method of producing a wood powder-containing compound by mixing a resin and wood powder.
JP-A-7-80834 JP-A-8-207068 JP 2003-245967 A Japanese Patent Publication No. 3-52342 JP 2003-103516 A JP 2007-84713 A

  The molded body made of the wood powder-containing compound obtained by the method described in Patent Document 5 is excellent in that it does not produce combustion residues during incineration, but the molded body is heavy, the mechanical strength is not sufficient, and further uses If a nail is struck by a crack, it will crack.

  When cellulose fibers are used instead of wood flour, the mechanical strength of the molded body can be increased, but if the cellulose fibers are not sufficiently defibrated, the cellulose is not uniformly dispersed in the molded body, Unevenness in mechanical strength occurs, making it impractical.

  The present applicant has previously filed an invention relating to a cellulose fiber-containing thermoplastic resin composition (Patent Document 6). Since the resin molded body obtained from the composition has good dispersibility of cellulose fibers, the appearance of the molded product is beautiful and the mechanical strength is also excellent.

  The present invention provides a production method for obtaining a cellulose fiber-containing thermoplastic resin composition in which cellulose fiber aggregates are defibrated and the cellulose fibers and the thermoplastic resin are uniformly mixed. It is an object of the present invention to provide a production method in which a molded body having a more beautiful appearance can be obtained by further increasing the ratio.

  Another object of the present invention is to provide a resin molded article formed from the cellulose fiber-containing thermoplastic resin composition obtained by the above production method.

The present invention provides the following inventions as means for solving the problems.
1. A step of obtaining a mixture in which a thermoplastic resin is adhered to a fibrillated cellulose fiber from a cellulose fiber aggregate and a thermoplastic resin;
Production of a cellulose fiber-containing thermoplastic resin composition having a step of melt-kneading the mixture in an extruder, passing through a mesh part of 60 to 200 mesh (JIS Z8801 and ISO 3310), and then extruding. Method.
2. The production method according to claim 1, wherein the step of obtaining the mixture is a step of adding the cellulose fiber aggregate and the thermoplastic resin to a mixer equipped with a heating means and stirring the mixture while heating.
3. The production method according to claim 1, wherein the step of obtaining the mixture is a step of charging the cellulose fiber aggregate and the thermoplastic resin into a biaxial high kneading type extruder and kneading while heating.
4). Obtaining the mixture comprises:
A step of defibrating the cellulose fiber aggregate by putting the cellulose fiber aggregate in a mixer having rotating blades as a stirring means and stirring at high speed;
Stirring after putting the thermoplastic resin in the mixer, melting the thermoplastic resin by the generated frictional heat, obtaining a mixture in which the thermoplastic resin is adhered to the defibrated cellulose fibers,
Stirring the mixture at low speed while cooling,
The manufacturing method of Claim 1 which has this.
5. Obtaining the mixture comprises:
When a cellulose fiber aggregate is put into a mixer having rotating blades as stirring means and the cellulose fiber aggregate is defibrated by stirring at high speed, a rod-shaped pulp sheet is used as the cellulose fiber aggregate, and the blades of the mixer A step of bringing the rod-shaped pulp sheet and the blade into contact with each other so that the angle formed between the blade and the blade is in a range of 45 ° to 90 °,
Stirring after putting the thermoplastic resin in the mixer, melting the thermoplastic resin by the generated frictional heat, obtaining a mixture in which the thermoplastic resin is adhered to the defibrated cellulose fibers,
Stirring the mixture at low speed while cooling,
The manufacturing method of Claim 1 which has this.
6). Obtaining the mixture comprises:
A step of defibrating the cellulose fiber aggregate with a defibrator to obtain cotton-like cellulose fibers;
The cotton-like cellulose fiber and the thermoplastic resin are put into a mixer having a rotating blade as a stirring means, and the thermoplastic resin is melted by the generated frictional heat to adhere the thermoplastic resin to the cellulose fiber. Obtaining a mixture;
Stirring the mixture while cooling;
The manufacturing method of Claim 1 which has this.
7). It is a resin molding obtained from the cellulose fiber containing thermoplastic resin composition obtained by the manufacturing method of any one of Claims 1-6, and the resin molding which satisfy | fills the following requirements (a) and (b) .

(A) The number of cellulose fiber lumps having a maximum diameter or a maximum length of 0.5 mm or more among cellulose fiber lumps existing on the surface of a resin molded body having a thickness of 3 mm obtained by injection molding from the composition. 5 pieces / 500 cm ² or less.

(B) The number of cellulose fiber lumps having a maximum diameter or a maximum length of 0.5 mm or more among cellulose fiber lumps present in a press-molded body having a thickness of 100 to 800 μm obtained from 7 g of the composition is 20 / 7g or less.
8). The resin molding of Claim 7 whose density is 0.4-1.3g / cm < ³ >.

  According to the method for producing a cellulose fiber-containing composition of the present invention, a mixture of fibrillated cellulose fibers and a thermoplastic resin can be obtained. For this reason, when shape | molding using a cellulose fiber containing composition, a moldability is also good, and a cellulose fiber is disperse | distributed uniformly in the obtained resin molding, and it is lightweight and has high mechanical strength.

<Method for producing cellulose fiber-containing thermoplastic resin composition>
Hereafter, the manufacturing method of this invention is demonstrated for every process.

[Step of obtaining a mixture in which a thermoplastic resin is adhered to defibrated cellulose fiber]
The first step is a step of obtaining a mixture in which the thermoplastic resin is adhered to the fibrillated cellulose fiber from the cellulose fiber aggregate and the thermoplastic resin. This process should just be what can obtain the said mixture and can process the next process.

  Cellulose fiber aggregates are a combination of many cellulose fibers, which may be natural products or industrial products, hemp fiber, bamboo fiber, cotton fiber, wood fiber, kenaf fiber, hemp fiber, jute fiber, banana Aggregates such as fibers and coconut fibers can be used.

  The cellulose fiber preferably has a high α-cellulose content from the viewpoint of high thermal stability, more preferably 80% by mass or more, still more preferably 85% by mass or more, and particularly preferably 90% by mass or more.

  As the cellulose fiber aggregate, a pulp sheet or a cut product thereof is preferable. The thickness, shape, and size of the pulp sheet or the cut product thereof are not particularly limited, and can be selected within a range in which the operation of adding to the mixer and the stirring operation can be performed smoothly.

  When the cellulose fiber aggregate is a sheet, for example, a sheet having a thickness of 0.1 to 5 mm, preferably 1 to 3 mm, a width of 1 to 50 cm, and a length of about 3 to 100 cm can be used.

  When the cellulose fiber aggregate is a cut product of a sheet, for example, a strip having a thickness of 0.1 to 5 mm, preferably 1 to 3 mm, a width of 2 mm to 1 cm, and a length of about 3 mm to 3 cm, or A rectangular shape having a side of about 2 mm to 1 cm is preferable.

  The moisture content of the cellulose fiber aggregate is preferably 20% by mass or less, more preferably 17% by mass or less, and still more preferably 15% by mass or less. A water content of 20% by mass or less is preferable because the temperature rise due to generation of frictional heat is facilitated in the next step, and the cellulose fiber aggregate is easily defibrated and no aggregate remains. The moisture content is determined by measuring moisture using the Karl Fischer method.

  If necessary, organic fibers other than cellulose fibers can be used. In the total amount of cellulose fibers and organic fibers, the ratio of cellulose fibers is preferably 50% by mass or more, more preferably. It is 55 mass% or more. Examples of organic fibers other than cellulose fibers include nylon fibers, polyester fibers, and acrylic fibers.

  As the thermoplastic resin, a resin selected from a crystalline resin having a melting point of 230 ° C. or less and an amorphous resin can be used.

  Examples of crystalline resins having a melting point of 230 ° C. or lower include polyethylene, polypropylene, polyamides 6, 11, 12, polybutylene terephthalate, polyacetal, polyvinyl alcohol, biodegradable resins (PBS, PBSA, PCL, PLA, cellulose acetate) System) and the like, and polyethylene and polypropylene are more preferable.

As the amorphous resin, one having a melt viscosity of 10 ² to 10 ⁵ poise (200 ° C., shear rate of 100 sec ⁻¹ ) measured with a capillary ohmmeter can be used, and GPPS, MIPS, HIPS, AS, ABS, PMMA Etc. are preferred.

  The total amount of cellulose fiber and thermoplastic resin is set according to the volume of the mixer and the like. The ratio of the cellulose fibers to the thermoplastic resin (when all are in an absolutely dry state) is preferably 5 to 500 parts by mass, more preferably 7 to 450 parts by mass, and more preferably 7 to 450 parts by mass with respect to 100 parts by mass of the thermoplastic resin. Preferably it is 10-400 mass parts.

  In particular, when increasing the blending ratio of cellulose fibers, for example, when blending more than 67 parts by mass of cellulose fibers with respect to 100 parts by mass of resin, it is desirable to use a thermoplastic resin having a low viscosity.

  For example, when polypropylene is used, the melt flow rate is preferably 20 to 200 g / 10 min under conditions of a temperature of 230 ° C. and a load of 21.6 N. When polyethylene is used, the melt flow rate is 190 ° C. The one having a load of 21.6 N is preferably 10 to 200 g / 10 minutes.

  Further, for example, when an ABS resin is used, the melt flow rate is preferably 10 to 200 g / 10 minutes under a condition of a temperature of 220 ° C. and a load of 100 N. When polystyrene is used, a condition of a temperature of 200 ° C. and a load of 50 N is preferable. 5 to 100 g / 10 min are preferred.

  Hereinafter, the first method to the fifth method will be described as examples of this step.

(1) First Method A first method for obtaining a mixture in which a thermoplastic resin is adhered to defibrated cellulose fibers is a method in which a cellulose fiber aggregate and a thermoplastic resin are put into a mixer equipped with heating means and heated. It is a method which has the process stirred while it is.

  In this step, if necessary, a thermoplastic resin and a cellulose fiber aggregate are preliminarily mixed, and then they are put into a Henschel mixer (for example, manufactured by Mitsui Mining Co., Ltd., equipped with a heater) and heated while stirring. The conditions at this time are as follows.

  A total of 1000 to 3000 g of the thermoplastic resin and cellulose fiber is put into a mixer having a mixing tank capacity of 20 L and kneaded at a peripheral speed of 10 to 50 m / sec for 10 to 30 minutes in the vicinity of the melting temperature of the used resin.

(2) Second method A second method for obtaining a mixture in which a thermoplastic resin is adhered to defibrated cellulose fibers is a method in which a cellulose fiber assembly and a thermoplastic resin are put into a biaxial high-kneading extruder, It is a method having a step of kneading while heating.

  In this step, after pre-mixing the thermoplastic resin and the cellulose fiber aggregate as needed (for example, in an amount of 50 kg), a twin-screw high-kneading extruder [for example, CTM, HTM65, screw diameter 65 mm, with hot cut (in water) cut] and melt kneaded at a screw rotation speed of 200 to 800 r / m in the vicinity of the melting temperature of the resin used.

(3) Third method A third method of obtaining a mixture in which a thermoplastic resin is adhered to defibrated cellulose fibers,
(Step 3-1) Step of defibrating the cellulose fiber aggregate by putting the cellulose fiber aggregate in a mixer having rotating blades as a stirring means and stirring at high speed,
(Step 3-2) The thermoplastic resin was melted by the generated frictional heat by stirring after the thermoplastic resin was put in the mixer, and the thermoplastic resin adhered to the fibrillated cellulose fiber. Obtaining a mixture;
(Step 3-3) Step of stirring the mixture at a low speed while cooling,
It is the method which has. Hereinafter, it demonstrates for every process.

[3-1 process]
In step 3-1, the cellulose fiber aggregate is put into a mixer having rotating blades as stirring means, and the cellulose fiber aggregate is defibrated by stirring at high speed.

  The mixer only needs to have rotating blades as stirring means, and preferably has heating means. For example, a Henschel mixer manufactured by Mitsui Mining Co., Ltd., FM20C / I (capacity 20 L), ( Kawata Supermixer SMV-20 (capacity 20 L) can be used.

  The rotating blades are usually composed of two upper blades and lower blades, or three upper blades, intermediate blades, and lower blades, but the number is not limited. The shape of the blade is not limited, but for example, the kneading type is used for the upper blade, the high circulation / high load is used for the lower blade, and the melt is used when the intermediate blade is used.

  In the step 3-1, it is preferable to stir the average peripheral speed of the rotating blades during stirring in the range of 10 to 100 m / second, more preferably the average peripheral speed is 10 to 90 m / second, and still more preferably the average peripheral speed is. Stir at 10-80 m / sec.

  The treatment in the step 3-1 is sufficient if the cellulose fiber aggregate can be sufficiently defibrated. For example, the time point when the cellulose fiber aggregate has been visually confirmed to have changed into a cotton-like shape can be obtained. Processing can be terminated. Since the average peripheral speed and stirring time of the rotating blades change depending on the type, shape, size, input amount, and the like of the cellulose fiber aggregate, the time point when it changes to cotton as described above may be used as a reference. Is preferred.

[Process 3-2]
In step 3-2, the thermoplastic resin was stirred in the mixer, and the thermoplastic resin was melted by the generated frictional heat, and the thermoplastic resin adhered to the fibrillated cellulose fibers. A mixture is obtained. Steps 3-1 and 3-2 can be made one continuous step without stopping the stirring of the mixer.

  In step 3-1, since the cellulose fiber aggregate is defibrated in the mixer, a required amount of thermoplastic resin is added thereto and stirred at high speed. This high-speed stirring generates frictional heat and raises the temperature in the mixer, so that the thermoplastic resin melts and adheres to the fibrillated cellulose fibers, and a mixture of cellulose fibers and the thermoplastic resin is obtained.

  In the step 3-2, it is preferable that the average peripheral speed of the rotating blades during stirring is in the range of 10 to 100 m / second, more preferably the average peripheral speed is 10 to 90 m / second, and still more preferably the average peripheral speed is. Stir at 10-80 m / sec. 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 in accordance with the increase in power and the temperature in the mixer so that the average peripheral speed falls within the above range.

  When stirring is continued in this state, the power increases again, so the mixture is discharged to the cooling mixer used in the next third step to be connected. At this time, in this mixture, the fibrillated cellulose fibers are adhered almost uniformly in the thermoplastic resin.

  In step 3-2, the mixer can be heated by a heating means in order to assist the temperature increase in the mixer and facilitate the production of a mixture of cellulose fibers and thermoplastic resin. The temperature at this time is preferably about 120 to 140 ° C.

[Process 3-3]
In step 3-3, the mixture obtained in step 3-2 is stirred at low speed while cooling. By the treatment in this step, the mixture is solidified (granulated by solidification). In step 3-3, in order to increase the cooling efficiency of the mixer, it is preferable to use a mixer (preferably having a cooling means) different from the mixer used in steps 3-1 and 3-2.

  In the step 3-3, it is preferable to stir in the range of the average peripheral speed of the rotating blades during stirring in the range of 1 to 30 m / second, more preferably the average peripheral speed is 2 to 25 m / second, and still more preferably the average peripheral speed is Stir at 3-25 m / sec. The stirring speed in step 3-3 is smaller than the stirring speed in steps 3-1 and 3-2.

  In the process in the step 3-3, the process in the step 3-3 can be completed when the mixture of the cellulose fiber and the thermoplastic resin is solidified to such an extent that it can be handled as a molding material. In addition, if the temperature inside the mixer rises too much due to the generation of frictional heat, the thermoplastic resin once solidified will be remelted. Therefore, it is preferable to control the temperature inside the mixer also in step 3-3.

By such treatment, a solidified product (granulated product) containing cellulose fibers and a thermoplastic resin is obtained, and can be used as a material for a resin molded body.

(4) Fourth Method A fourth method of obtaining a mixture in which a thermoplastic resin is adhered to defibrated cellulose fibers,
(Step 4-1) When the cellulose fiber aggregate is defibrated by putting the cellulose fiber aggregate into a mixer having rotating blades as stirring means and stirring at high speed, a rod-shaped pulp sheet as the cellulose fiber aggregate , The angle between the blades of the mixer is in the range of 45 ° to 90 °, the step of contacting the rod-shaped pulp sheet and the blades to defibrate,
(Step 4-2) The thermoplastic resin is melted by the generated frictional heat by stirring after the thermoplastic resin is put in the mixer, and the thermoplastic resin adheres to the fibrillated cellulose fiber. Obtaining a mixture;
(Step 4-3) Step of stirring the mixture at a low speed while cooling,
It is the method which has.

[4-1 process]
In step 4-1, the cellulose fiber aggregate is put into a mixer having rotating blades as stirring means, and the cellulose fiber aggregate is defibrated by stirring at high speed.

The cellulose fiber aggregate used in the present invention is a rod-shaped pulp sheet. The “bar shape” means an elongated shape having a strength higher than that of a single sheet. As a rod-shaped pulp sheet, for example,
(I) A pulp sheet wound once or twice or more (preferably 2-5 turns) and rolled into a cylindrical shape,
(II) One or two or more rolls of a pulp sheet rolled into a cylindrical shape, and then crushed in the radial direction into an elongated plate shape,
(III) The pulp sheet is folded into one or more times (preferably 2 to 10 times) so as to be in different directions, and is formed into an elongated plate shape,
(IV) A pulp sheet folded in the same direction once or a plurality of times (preferably 2 to 10 times) into a long and narrow plate shape,
(V) A pulp sheet that is folded in a random direction once or a plurality of times (preferably 2 to 10 times) into an elongated plate shape, or the like can be used.

  The shape of the pulp sheet is not particularly limited, and may be any shape as long as it can be formed in the above-mentioned forms (I) to (V), such as a rectangle, a square, a circle, a sector, a triangle, a pentagon or more polygon. Can be used.

  For example, a pulp sheet having a thickness of 0.1 to 5 mm, preferably 1 to 3 mm, a width of 10 to 50 cm, and a length of about 60 to 100 cm can be used.

The pulp sheet preferably has a burst strength measured by the method described in JIS P8112 and P8131 (using a Murren burst strength tester) in the range of 0.5 to 10.0 kPam ² / g. If it is within this range, the above-described methods (I) to (V) can be applied to obtain a rod-like pulp sheet. Even if the tensile strength is less than the lower limit, the number of windings and the number of foldings may be increased.

  The cylindrical form (I) is, for example, wound in a cylindrical form as shown in FIGS. 1 (a) and 1 (b). FIG. 1 shows a state where the pulp sheet is wound twice and a half. The crushed one becomes the plate-like form (II).

  The plate-like form of (III) is, for example, as shown in FIGS. 2 (a) and 2 (b), in which a pulp sheet is alternately folded into different directions to form an elongated plate (ie, Folded in a bellows shape). FIG.2 (c) has shown what was folded in the same direction corresponding to the plate-shaped form of (IV).

  As long as the rod-shaped pulp sheet has the same degree of strength as the cylindrical or plate-like pulp sheet of (I) to (V) above, it is simply one sheet without being rolled or folded. It may be just cut the sheet.

  In consideration of workability, the rod-like pulp sheet preferably has a ratio of length / width (diameter) of 3 or more.

  The mixer only needs to have rotating blades as stirring means, and preferably has heating means. For example, a Henschel mixer manufactured by Mitsui Mining Co., Ltd., FM20C / I (capacity 20 L), ( Kawata Supermixer SMV-20 (capacity 20 L) can be used.

  The rotating blades are usually composed of two upper blades and lower blades, or three upper blades, intermediate blades, and lower blades, but the number is not limited. The shape of the blade is not limited, but for example, the kneading type is used for the upper blade, the high circulation / high load is used for the lower blade, and the melt is used when the intermediate blade is used.

  In step 4-1, it is preferable to stir in the range where the average peripheral speed of the rotating blades during stirring is in the range of 10 to 100 m / second, more preferably the average peripheral speed is 10 to 90 m / second, and still more preferably the average peripheral speed is. Stir at 10-80 m / sec.

  In step 4-1, as shown in FIG. 3, the fiber sheet is defibrated so that the angle formed by the rod-shaped pulp sheet and the blades of the mixer is within a predetermined range. FIG. 3 is for explaining the contact state between the rod-shaped pulp sheet and the blades of the mixer, and is not for explaining the structure of the mixer.

  In step 4-1, the angle α formed by the center line of the bar-shaped pulp sheet 1 shown in FIG. 3 and the center line of the blades 11 of the mixer 10 (or the surface of the circular rotating surface generated by the rotating blades 11) is: It is 45 to 90 °, preferably 60 to 90 °, more preferably 75 to 90 °, and even more preferably 90 ° or an angle close thereto. In addition, as described above, when the mixer has a two-blade configuration of the upper blade and the lower blade, or a three-blade configuration of the upper blade, the intermediate blade, and the lower blade, the angle α formed with at least the first upper blade in contact is within the above range. As long as

  In step 4-1, in the state shown in FIG. 3, the end of the rod-like pulp sheet 1 (the end far from the blade 11) is mechanically or artificially fixed, and along with the progress of defibration, the above The rod-shaped pulp sheet 1 is pushed toward the rotating blade 11 while maintaining the predetermined angle α. Then, when the fixed end of the rod-shaped pulp sheet 1 approaches the rotating blade 11, the fixed state is released. When defibrating in this manner, the defibrating portion (contact portion) at the tip of the rod-shaped pulp sheet 1 also vibrates due to the rotational pressure of the blades 11, and thus the angle α may vary somewhat. The variation range of the angle α may be a range of about ± 10 ° from the initial set angle α.

  The treatment in the step 4-1 is sufficient if the cellulose fiber aggregate can be sufficiently defibrated. For example, the time point when the cellulose fiber aggregate has been visually confirmed to have changed into a cotton-like shape can be confirmed. Processing can be terminated. Since the average peripheral speed and stirring time of the rotating blades change depending on the type, shape, size, input amount, and the like of the cellulose fiber aggregate, the time point when it changes to cotton as described above may be used as a reference. Is preferred.

  By applying such a 4-1 step defibrating method, for example, as in the case of the third method, the defibrated state is further improved compared to the case where the pulp sheet is defibrated as it is with a mixer. Dispersibility when mixed with a plastic resin is also improved.

  Steps 4-2 and 4-3 can be processed in the same manner as steps 3-2 and 3-3 of the third method described above. By such treatment, a solidified product (granulated product) containing cellulose fibers and a thermoplastic resin is obtained, and can be used as a material for a resin molded body.

(5) Fifth Method A fifth method of obtaining a mixture in which a thermoplastic resin is adhered to defibrated cellulose fibers,
(5-1) A step of defibrating the cellulose fiber aggregate with a defibrator to obtain cotton-like cellulose fibers;
(5-2) The cotton-like cellulose fiber and the thermoplastic resin are put into a mixer having rotating blades as a stirring means, and the thermoplastic resin is melted by the generated frictional heat, and the cellulose fiber is heated. Obtaining a mixture having a plastic resin attached thereto;
(5-3) a step of stirring the mixture while cooling;
It is the method which has.

[5-1 process]
In step 5-1, the cellulose fiber aggregate is defibrated by a defibrator to obtain cotton-like cellulose fibers.

  The defibrating machine can be uncoiled by acting mechanically on the cellulosic fiber aggregate to form a flocculent cellulosic fiber (which is intertwined with a large number of cellulosic fibers). Anything is acceptable. The defibrator is preferably one that employs a dry defibrating method, and examples thereof include those used for defibrating commercially available waste paper. As such a defibrating machine, a defibrating machine (Model FF-270, FF-280, FF-290) manufactured by Ruikou Co., Ltd., a recycling breaker RB-100 manufactured by Ikegami Machinery Co., Ltd. Examples include a waste paper defibrator manufactured by the association, a small dry defibrator “Fiber Riser” manufactured by West Japan Technology Development Co., Ltd., and a turbo mill manufactured by Turbo Industry Co., Ltd.

  The treatment in the 5-1 step is not limited as long as the cellulose fiber aggregate can be sufficiently defibrated. For example, the time when the cellulose fiber aggregate has been visually confirmed to be cotton-like can be confirmed. This process can be terminated. Since the average peripheral speed and stirring time of the rotating blades change depending on the type, shape, size, input amount, and the like of the cellulose fiber aggregate, the time point when it changes to cotton as described above may be used as a reference. Is preferred.

  Steps 5-2 and 5-3 can be processed in the same manner as steps 3-2 and 3-3 in the third method. By such treatment, a solidified product (granulated product) containing cellulose fibers and a thermoplastic resin is obtained, and can be used as a material for a resin molded body.

[Processing with an extrusion molding machine having a mesh part]
In the next step, after melt-kneading the mixture of the defibrated cellulose fibers obtained by the above-described first to fifth methods and the like with a thermoplastic resin by an extruder, 60 to 150 mesh ( Pass through the mesh part of JIS Z8801 and ISO 3310) and then extrude.

  The mesh part is made of metal such as stainless steel, and has a sieve shape in which a mesh is formed inside the frame. The mesh part can be arranged in the vicinity of the outlet of the extruder. The mesh part mesh is 60-200 mesh, 60-150 mesh is preferable, and 60-100 mesh is more preferable.

  The mesh part can be used by combining two or more different meshes. For example, if the composition flow direction is upstream (closer to the material inlet of the extruder) to downstream (closer to the outlet of the extruder), a smaller mesh (having a larger opening) is placed on the upstream side. In addition, a larger mesh (having a smaller mesh size and having a mesh size of 60 to 200 mesh) can be disposed on the downstream side.

  As a combination of two mesh portions having different meshes, a mesh portion of 10 to 20 mesh can be arranged on the upstream side, and a mesh portion of 60 to 200 mesh can be arranged on the downstream side. The two mesh portions may be arranged in an overlapped state, or may be arranged with an interval of about 0.01 to 0.1 cm.

  Since the fiber or the fiber lump that has not been defibrated can be removed by the treatment in this step, the dispersibility of the cellulose fiber when the molded body is produced is further enhanced. In addition, when two meshes with different openings are separated and placed as described above, a larger fiber lump can be removed with a smaller mesh (with a larger opening) and a larger mesh (with a larger opening). This is preferable because a smaller fiber lump can be removed with a smaller one).

<Resin molding>
The resin molded body of the present invention can be obtained by molding into a desired shape with an extruder or an injection molding machine using a solidified product (granulated product) of the cellulose fiber-containing composition obtained by the production method of the present invention. it can. In addition, when the particle size of the said solidified material (granulated material) is uneven, it can grind | pulverize before shaping | molding and can arrange | equalize a particle size as needed.

  In the production of the resin molded product of the present invention, a thermoplastic resin (thermoplastic resin for molded product) is further added in addition to the solidified product (granulated product) of the cellulose fiber-containing composition as necessary. Can do. As the thermoplastic resin for the molded body, a known thermoplastic resin can be used in addition to the resin used for producing the cellulose fiber-containing composition. The thermoplastic resin for the molded body and the thermoplastic resin of the cellulose fiber-containing composition are preferably the same or compatible, but if necessary, the compatibility is improved by using a known compatibilizer. You may use what does not have.

  When manufacturing resin moldings, carbon black, inorganic pigments, organic pigments, dyes, auxiliary colorants, dispersants, stabilizers, plasticizers, modifiers, UV absorbers or light stabilizers, and antioxidants as necessary. Agents, antistatic agents, lubricants, mold release agents, crystal accelerators, crystal nucleating agents, elastomers for improving impact resistance, and the like can be blended.

The resin molded body of the present invention is manufactured using cellulose fibers containing a cellulose fiber-containing composition as a molding material defibrated by a defibrating machine, so that the fibrillated cellulose fibers in the resin molded body are uniform. Are distributed. For this reason, the resin molding which satisfy | fills the following requirements (a) and (b) can be obtained.
(A) The number of cellulose fiber lumps having a maximum diameter or a maximum length of 0.5 mm or more among cellulose fiber lumps existing on the surface of a resin molded body having a thickness of 3 mm obtained by injection molding from the composition. 5/500 cm ² or less (preferably 3/500 cm ² or less).
(B) The number of cellulose fiber lumps having a maximum diameter or a maximum length of 0.5 mm or more among cellulose fiber lumps present in a press-molded body having a thickness of 100 to 800 μm obtained from 7 g of the composition is 20 / 7 g or less (preferably 10 pieces / 7 g or less).

  The resin molded body of the present invention has a non-foamed structure, but can be formed into a foamed structure (foam) using a known foaming agent as necessary. Regardless of the non-foamed structure and the foamed structure, the resin molded body of the present invention has cellulose fibers uniformly dispersed in the thermoplastic resin, and they are entangled with each other, so that fine gaps are formed inside. Since it is formed, it can be reduced in weight, and even when nailing, it does not crack.

  The cell structure of the foam may be a closed cell structure or an open cell structure, or both may be mixed. The expansion ratio is usually 1.02 times or more, preferably 1.03 times or more, and more preferably 1.05 times. If the expansion ratio is less than 1.02, satisfactory nails cannot be obtained.

  You may manufacture a foam by any method of the method of using natural foaming without using a foaming agent, and the method of using a foaming agent. When using a foaming agent, the foaming agent which generate | occur | produces volatile gas and / or volatile gas, or water can be used.

  Examples of blowing agents that generate volatile gases or blowing agents that generate volatile gases include hydrocarbons such as propane, butane, pentane, and hexane, halogenated hydrocarbons such as HCFC22, HFC-142b, and HFC-134a, and chloride. Mention may be made of organic gases such as chlorinated hydrocarbons such as methylene and methyl chloride, and inorganic gases such as carbon dioxide and nitrogen. The blending amount of the foaming agent when these are used is not particularly limited, and may be appropriately set according to the type of foaming agent to be used and the desired expansion ratio.

  Decomposable foaming agents such as citric acid, azo compounds, hydrazide compounds, azide compounds, and carbonates can also be used. When using these, the ratio of the foaming agent is, for example, preferably 0.1 to 20 parts by mass, more preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the resin, depending on the expansion ratio and the like. .

  The foaming agent may be used by mixing with a thermoplastic resin, or may be used by impregnating the thermoplastic resin. Further, the foaming agent may be added or press-fitted into the melt-kneaded thermoplastic resin.

  When water is used as the foaming agent, water may be added by directly attaching a pump or the like to the extruder, but it may be impregnated in advance with cellulose fibers to be blended with the thermoplastic resin. It is preferable to impregnate water so that it becomes 0.1-20 mass parts with respect to 100 mass parts of plastic resins, More preferably, it becomes 0.5-10 mass parts.

  Further, moisture may be absorbed into the solidified product (granulated product) of the cellulose fiber-containing composition, and foam molding may be performed using this. In this case, it is preferable to absorb moisture so as to be 0.1 to 20 parts by mass, and more preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the molded body.

  In addition to the foaming agent, a foaming aid (or foaming nucleating agent) such as talc or calcium carbonate may be added as necessary. The ratio of the foaming aid (or foaming nucleating agent) may be 0.1 to 4 parts by mass with respect to 100 parts by mass of the resin.

Preferably the density of the resin molding of the present invention is 0.4 to 1.5 g / cm ^3, more preferably 0.5~1.4g / cm ^3, 0.6~1.4g / Although it is more preferable that it is cm ³ , depending on the application, the density of the molded body may be increased by compression molding.

  The resin molded body of the present invention includes packaging materials for electrical and electronic parts, building materials (wall materials, etc.), civil engineering materials, agricultural materials, automobile parts (interior materials, exterior materials), packaging materials (containers, cushioning materials, etc.), It can be applied to household materials (daily necessities, etc.). In particular, since there is almost no cellulose fiber lump existing on the surface of the resin molded body and the surface appearance is beautiful, it is suitable as an exterior material for various products.

Production Example 1 (Third method for obtaining a mixture in which a thermoplastic resin is adhered to defibrated cellulose fibers)
[3-1 process]
Heat the heater mixer (upper blade: kneading type, lower blade: high circulation / high load, with heater and thermometer, capacity 20L, Henschel mixer FM20C / I, manufactured by Mitsui Mining Co., Ltd.) to 140 ° C. The following cellulose sheet was added and stirred at an average peripheral speed of 50 m / sec. After about 2 minutes, the cellulose fiber product changed to cotton.
(Cellulose sheet)
Pulp NDP-T manufactured by Nippon Paper Industries Co., Ltd., having an average fiber diameter of 25 μm, an average fiber length of 1.8 mm, and an α-cellulose content of 90%, a sheet having a width of 60 cm, a length of 80 cm and a thickness of 1.1 mm, Cut to 20 cm and 80 cm in length.

[Process 3-2]
Subsequently, after polypropylene (J139 manufactured by Sun Allomer Co., Ltd.) was charged into the heater 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. When the mixer temperature reached 120 ° C., MPP was added and stirring was continued.

  At about 10 minutes, power started to increase. 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 again due to the continued low speed stirring. After 1 minute and 30 lines from 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.

[Process 3-3]
Cooling mixer [Rotating blade: Standard blade for cooling, with water cooling means (20 ° C) and thermometer, capacity 45L, product name cooler mixer FD20C / K, manufactured by Mitsui Mining Co., Ltd.) Start stirring at an average peripheral speed of 10m / sec. The stirring was terminated when the temperature in the mixer reached 80 ° C. The mixture of cellulose fibers and polypropylene was solidified by the treatment in Step 3-3, and a granulated product having a diameter of about several mm to 2 cm was obtained.

Production Example 2 (Fourth method for obtaining a mixture in which a thermoplastic resin is adhered to defibrated cellulose fibers)
[4-1 process]
A heater mixer (upper blade: kneading type, lower blade: high circulation / high load, with heater and thermometer, capacity 200L) is heated to 140 ° C, and the following bar-shaped pulp sheet is mixed at a predetermined angle α. (See FIG. 3) and stirred at an average peripheral speed of 50 m / sec. At about 3 minutes, the rod-like pulp sheet changed to cotton.
(Bar-shaped pulp sheet)
A sheet of 40 cm wide, 80 cm long, 1 mm thick, made of bamboo pulp made by Phoenix (average fiber length 1.7 mm, α cellulose content 90%, burst strength 3.9 kPam ² / g) is wound five times. The cylindrical shape (cylindrical sheet in FIG. 1).

[4-2 process]
Subsequently, after polypropylene (J139 manufactured by Sun Allomer Co., Ltd.) was charged into the heater mixer, stirring was continued at an average peripheral speed of 50 m / sec. The current value of the motor at this time was 30A. When the mixer temperature reached 120 ° C., MPP was added and stirring was continued.

  At about 10 minutes, power started to increase. After another minute, the current value increased to 50 A, so the peripheral speed was reduced to a low speed of 25 m / sec. Furthermore, the power started to increase again due to the continued low speed stirring. Since the current value reached 60 A after 1 minute and 30 lines from the start of low-speed rotation, the mixer was opened and discharged to the connected cooling mixer.

[Process 4-3]
Cooling mixer [Rotating blade: Standard blade for cooling, with water cooling means (20 ° C) and thermometer, capacity 500L) Stirring was started at an average peripheral speed of 10m / sec and stirred when the temperature in the mixer reached 80 ° C. Ended. The mixture of cellulose fiber and polypropylene was solidified by the treatment in 4-3 step, and a granulated product having a diameter of about several mm to 2 cm was obtained.

Production Example 3 (Fifth method for obtaining a mixture in which a thermoplastic resin is adhered to defibrated cellulose fibers)
[5-1 process]
The same cellulose sheet as in Production Example 1 was put into a defibrating machine (Turbo Industry Co., Ltd .; Turbo Mill T-250) and defibrated. Visually, it was confirmed that the fiber was completely defibrated. Operating conditions are 8300rpm. The processing capacity was about 20 kg / h.

[5-2 process]
Subsequently, after polypropylene (J139 manufactured by Sun Allomer Co., Ltd.) was charged into the heater 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. When the mixer temperature reached 120 ° C., MPP was added and stirring was continued.

  At about 10 minutes, power started to increase. 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 again due to the continued low speed stirring. After 1 minute and 30 lines from 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.

[Process 5-3]
Cooling mixer [Rotating blade: Standard blade for cooling, with water cooling means (20 ° C) and thermometer, capacity 45L, product name cooler mixer FD20C / K, manufactured by Mitsui Mining Co., Ltd.) Start stirring at an average peripheral speed of 10m / sec. The stirring was terminated when the temperature in the mixer reached 80 ° C. The mixture of cellulose fibers and polypropylene was solidified by the treatment in the 5-3 step, and a granulated product having a diameter of about several mm to 2 cm was obtained.

Examples and Comparative Examples After putting the granulated material shown in Table 1 into a twin-screw extruder (Nippon Steel Works, TEX30), melt-kneading (cylinder temperature 190 ° C), two mesh parts fixed to the inner wall of the cylinder After passing, it was extruded and formed into pellets to obtain a cellulose fiber-containing thermoplastic resin composition.

〔Test method〕
(1) Requirement (a): Number of cellulosic fiber lumps present on the surface of the molded body (pieces / 500 cm ² )
Ten color plates (50 mm × 100 mm × 3 mm) were molded with an injection molding machine at a cylinder temperature of 190 ° C. using the compositions of Examples and Comparative Examples. One surface of 10 pieces of the color plate is observed at an enlargement boundary of 5 times or more, and cellulose caused by undefibrated cellulose fibers having a maximum diameter or maximum length of 0.5 mm or more in a total of 500 cm ² The number of fiber masses was counted.

(2) Requirement (b): Number of cellulosic fiber lumps present on the surface of the molded body (pieces / 7 g)
Using 7 g of each of the compositions of Examples and Comparative Examples, a sheet having a thickness of about 450 μm was obtained by press molding with a press machine (Shindo Metal Industry Co., Ltd .; SFA-37D). The press molding conditions were a press machine setting temperature of 230 ° C., a residual heat of 2 minutes, a pressurization of 100 kg / cm ² for 10 seconds, and a cooling (water circulation cooling inside the press plate) for 40 seconds. For the obtained sheet, the undissolved cellulose fibers having the maximum diameter or the maximum length of 0.5 mm or more in the same manner as in “(1) Number of cellulosic fiber lumps existing on the surface of the molded body (pieces / 500 cm ² )”. The number of cellulosic fiber masses due to the fines was counted.

(3) Extrudability The compositions of Examples and Comparative Examples were continuously produced in a twin-screw extruder (Nippon Steel Works, TEX30) at an extrusion temperature of 200 ° C., a screw rotation speed of 260 r / p, and a feed amount of 18 kg / h. Pushed out for 1 hour. The extrudability at this time was evaluated according to the following criteria.
○: No abnormality (no vent-up or die pressure abnormality)
X: Abnormal (bent up and / or die pressure abnormal)

(A) is a perspective view of the cylindrical pulp sheet used by manufacture example 2 (4th method), (b) is a top view. (A) is a perspective view of a plate-like pulp sheet of another form used in Production Example 2 (fourth method), (b) is a plan view of (a), and (c) is a plate of another form. The top view of a pulp sheet. The figure for demonstrating the fibrillation method of the manufacture example 2 (4th method).

Claims (6)

A step of obtaining a mixture in which a thermoplastic resin is adhered to a fibrillated cellulose fiber from a cellulose fiber aggregate and a thermoplastic resin;
Production of a cellulose fiber-containing thermoplastic resin composition having a step of melt-kneading the mixture in an extruder, passing through a mesh part of 60 to 200 mesh (JIS Z8801 and ISO 3310), and then extruding. Method.   The production method according to claim 1, wherein the step of obtaining the mixture is a step of adding the cellulose fiber aggregate and the thermoplastic resin to a mixer equipped with a heating means and stirring the mixture while heating.   The production method according to claim 1, wherein the step of obtaining the mixture is a step of charging the cellulose fiber aggregate and the thermoplastic resin into a biaxial high kneading type extruder and kneading while heating. Obtaining the mixture comprises:
A step of defibrating the cellulose fiber aggregate by putting the cellulose fiber aggregate in a mixer having rotating blades as a stirring means and stirring at high speed;
Stirring after putting the thermoplastic resin in the mixer, melting the thermoplastic resin by the generated frictional heat, obtaining a mixture in which the thermoplastic resin is adhered to the defibrated cellulose fibers,
Stirring the mixture at low speed while cooling,
The manufacturing method of Claim 1 which has this. Obtaining the mixture comprises:
When a cellulose fiber aggregate is put into a mixer having rotating blades as stirring means and the cellulose fiber aggregate is defibrated by stirring at high speed, a rod-shaped pulp sheet is used as the cellulose fiber aggregate, and the blades of the mixer A step of bringing the rod-shaped pulp sheet and the blade into contact with each other so that the angle formed between the blade and the blade is in a range of 45 ° to 90 °,
Stirring after putting the thermoplastic resin in the mixer, melting the thermoplastic resin by the generated frictional heat, obtaining a mixture in which the thermoplastic resin is adhered to the defibrated cellulose fibers,
Stirring the mixture at low speed while cooling,
The manufacturing method of Claim 1 which has this. Obtaining the mixture comprises:
A step of defibrating the cellulose fiber aggregate with a defibrator to obtain cotton-like cellulose fibers;
The cotton-like cellulose fiber and the thermoplastic resin are put into a mixer having a rotating blade as a stirring means, and the thermoplastic resin is melted by the generated frictional heat to adhere the thermoplastic resin to the cellulose fiber. Obtaining a mixture;
Stirring the mixture while cooling;
The manufacturing method of Claim 1 which has this.

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