JP2008297479A - 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 capable of obtaining the one containing a fibrillated cellulose fiber. <P>SOLUTION: The method for producing a cellulose fiber-containing thermoplastic resin composition comprises: a process where, when a cellulose fiber assembly is fed to a mixer having a rotary blade as a stirring means, and the cellulose fiber assembly is fibrillated by a high-speed stirring, as the cellulose fiber assembly, a bar-shaped pulp sheet is used, and the bar-shaped pulp sheet and the blade of the mixer are brought into contact in such a manner that the angle between the pulp sheet and the blade is controlled to the range of 45 to 90° and are fibrillated; a process where a thermoplastic resin is fed to the mixer, the mixture is stirred, and the thermoplastic resin is melted by generated frictional heat, so as to obtain a mixture in which the thermoplastic resin is attached to the fibrillated cellulose fiber; and a process where the mixture is stirred at a low speed while being cooled. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a cellulose fiber-containing thermoplastic resin composition, and a resin molded product molded using the composition obtained by the production 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.

As a means for solving the problems, the present invention
When the cellulose fiber aggregate is defibrated by putting the cellulose fiber aggregate in a mixer having rotating blades as stirring means and stirring at high speed, a rod-like 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 adheres to the defibrated cellulose fibers,
A method for producing a cellulose fiber-containing thermoplastic resin composition (hereinafter abbreviated as “cellulose fiber-containing composition”) having a step of stirring at low speed while cooling the mixture is provided.

  High-speed stirring and low-speed stirring mean the difference in relative peripheral speed (m / sec; linear velocity on the outer periphery of the rotating blade), and high-speed stirring means that the peripheral speed is larger than that of low-speed stirring. .

This invention 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 as a solution of another subject, The said shaping | molding Provided is a resin molded body in which the number of cellulose fiber lumps having a maximum diameter or maximum length of 0.5 mm or more among cellulose fiber lumps existing on the body surface is 10/500 cm ² or less.

  The smaller the number of cellulose fiber lumps having a maximum diameter or a maximum length of 0.5 mm or more among the cellulose fiber lumps existing on the surface of the molded body, the more defibrated state of the cellulose fibers in the cellulose fiber-containing composition as a raw material is Means good (less defibrated material).

  According to the method for producing a cellulose fiber-containing composition of the present invention, a mixture of defibrated 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 composition>
Although the manufacturing method of the cellulose fiber containing composition of this invention is demonstrated for every process, in this invention, two or more processes may be made into one and one process may be isolate | separated into two or more.

[First step]
In the first step, 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.

  As the pulp sheet, those containing various cellulose fibers selected from hemp fiber, bamboo fiber, cotton fiber, wood fiber, kenaf fiber, hemp fiber, jute fiber, banana fiber, coconut fiber and the like 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.

  The moisture content of the pulp sheet 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 moisture measurement using the Karl Fuscher method.

  The pulp sheet can use organic fibers other than cellulose fibers as necessary, but the ratio of cellulose fibers is 50% by mass or more in the total amount of cellulose fibers and organic fibers. More preferably, the ratio of the cellulose fiber is 55% by mass or more. Examples of organic fibers other than cellulose fibers include nylon fibers, polyester fibers, and acrylic fibers.

  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 first step, it is preferable to stir in the range of 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 10 Stir at ~ 80 m / sec.

  In the first step, as shown in FIG. 3, the fiber sheet is defibrated so that the angle between the rod-shaped pulp sheet and the blades of the mixer falls 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 the first step, the angle α between the center line of the rod-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 45. It is -90 degrees, Preferably it is 60-90 degrees, More preferably, it is 75-90 degrees, and it is still more preferable that it is 90 degrees or the angle approximated to it. 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 the first step, the end of the rod-like pulp sheet 1 (the end far from the blade 11) is mechanically or artificially fixed in the state shown in FIG. The rod-shaped pulp sheet 1 is pushed in toward the rotating blades 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 first step is not limited as long as the cellulose fiber aggregate can be sufficiently defibrated. For example, the point in time when the cellulose fiber aggregate has been visually confirmed to be cottony can be confirmed. The end of 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 defibrating method of the first step, for example, as in the invention of Patent Document 6, the defibrated state is further improved as compared with the case where the pulp sheet is defibrated as it is with a mixer. Dispersibility when mixed with a plastic resin is also improved.

[Second step]
In the second step, the thermoplastic resin is put into the mixer and then stirred, so that the thermoplastic resin is melted by the generated frictional heat, and the thermoplastic fiber is defibrated from the rod-shaped pulp sheet. A mixture with resin attached is obtained. The 1st process and the 2nd process can be made into one continuous process, without stopping stirring of a mixer.

  In the first step, since the cellulose fiber aggregate (rod-like pulp sheet) 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 second step, it is preferable to stir in the range of 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 10 Stir at ~ 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 the second step, the mixer can be heated by a heating means in order to assist the temperature increase in the mixer and facilitate the production of the mixture of cellulose fibers and thermoplastic resin. The temperature at this time is preferably about 120 to 140 ° C.

  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.

  As crystalline resins having a melting point of 230 ° C. or less, polyethylene, polypropylene, polyamides 6, 11, 12, polybutylene terephthalate, polyvinyl alcohol, biodegradable resins (PBS, PBSA, PCL, PLA, cellulose acetate) Etc. are preferable, 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 minutes under the 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.

[Third step]
In the third step, the mixture obtained in the second step is stirred at a low speed while being cooled. By the treatment in this step, the mixture is solidified (granulated by solidification). In the third step, 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 the first step and the second step.

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

  In the treatment in the third step, the point in time 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 can be terminated. In addition, since the thermoplastic resin once solidified will melt again if the temperature in the mixer rises too much due to generation of frictional heat, it is preferable to manage the temperature in the mixer also in the third step.

  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.

[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, since the said solidified material (granulated material) is uneven in particle size, 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.

Since the resin molded body of the present invention uses a cellulose fiber-containing composition, the fibrillated cellulose fibers are uniformly dispersed in the resin molded body. For this reason, the number of cellulose fiber masses having a maximum diameter or a maximum length of 0.5 mm or more among the cellulose fiber masses existing on the surface of the molded resin molded body using the cellulose fiber-containing composition is 10/50 cm ² or less. Preferably 5 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 foaming 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, the molded body obtained in the third step or subsequent molding may absorb moisture, and this may be foam-molded. 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.).

Example 1
Using the components shown in Table 1, a cellulose fiber-containing composition was produced by the following method.

[First step]
Heat the heater mixer (upper blade: kneading type, lower blade: for high circulation / high load, with heater and thermometer, capacity 200L) to 140 ° C, and make the rod-shaped pulp sheet shown in Table 1 at a predetermined angle α. The mixture was put into a mixer (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.

[Second step]
Subsequently, after introducing polypropylene 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.

[Third step]
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. By the treatment in the third step, the mixture of cellulose fibers and polypropylene was solidified, and a granulated product having a diameter of about several mm to 2 cm was obtained.

  Using the obtained granulated product, extrusion molding was performed using a twin screw extruder to obtain a resin molded body of the present invention. The cylinder temperature was 190 ° C. Formability (kneading property, extrudability) using a twin screw extruder was good.

Examples 2-5
It carried out similarly to Example 1 except having changed the mixing | blending component of the raw material.

Example 6
2 parts by weight of 2,2′-azobisisobutyronitrile as a foaming agent was added to 100 parts by mass of the composition of Example 1 to obtain a foam molded article.

Comparative Examples 1 and 2
Comparative Example 1 is Example 3 of Japanese Patent Application Laid-Open No. 2007-84713 (Patent Document 6), and Comparative Example 2 uses PP and crystalline cellulose, and performs the processes in the first to third steps of Examples 1 to 5. Without doing, it was extruded using a twin screw extruder in the same manner as in Examples 1 to 5, and Comparative Example 3 was a folding sheet.

〔Test method〕
(1) 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 at a cylinder temperature of 190 ° C. with an injection molding machine. 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) Bending strength (MPa)
Measurement was performed in accordance with ISO178.

(3) Flexural modulus (MPa)
Measurement was performed in accordance with ISO178.

(4) Charpy impact strength (kJ / m ² )
The notched Charpy impact strength was measured according to ISO 179 / 1eA.

(5) Nailing property 2 parts by weight of 2,2′-azobisisobutyronitrile was added as a foaming agent, and foam molding was performed to obtain a molded body having a length of 200 mm, a width of 400 mm, and a thickness of 10 mm. Two of these were stacked to a thickness of 20 mm, and five nails (length 34 mm, thickness 2 mm) were struck on one side to a depth of 16 mm at intervals of about 60 mm in the horizontal direction at a position of 100 mm. The nails at both ends were struck at a position about 60 mm away from the edge of the plate.

  When five nails are struck in this way, there is no cracking in the molded body in all cases, and when there is no bulge in the contact portion between the molded body and the nail (marked with ○), all or a part is molded. Evaluation was made by cracking in the body or swell at the contact portion between the molded body and the nail (indicated by ×).

PP: Polypropylene, PMB60A manufactured by Sun Allomer Co., Ltd.
ABS: ABS resin, Sebian V660 of Daicel Polymer Co., Ltd.
Polylactic acid: Poly L lactic acid resin and commercially available poly L lactic acid resin were used. A D-form having 1.2% and a weight average molecular weight of 17,000 in terms of PMMA was used.

The cylindrical sheet in FIG. 1: made of bamboo pulp (average fiber length 1.7 mm, α cellulose content 90%, burst strength 3.9 kPam ² / g) made by Phoenix, width 40 cm, length 80 cm, thickness 1 mm sheet wound five times into a cylindrical shape Fig. 2 plate sheet: the above sheet (Phoenix bamboo pulp) folded alternately 5 times in different directions as shown in Fig. 2 (b) Cellulose Shred (cellulosic fiber aggregate): the above sheet (Phoenix bamboo pulp) cut into 3 mm square with a shredder Crystalline cellulose: JRS PHARMA Cellulose powder Particle size> 250 μm (60 mesh) <1%
> 75μm (200 mesh) 22%
> 32μm (470 mesh) 85%
Cellulose sheet folding: The above sheet (Phoenix Bamboo Pulp) is folded twice into a 40 cm long and 20 cm wide MPP: acid-modified polypropylene, Umex 1010 manufactured by Sanyo Chemical Industries, Ltd.

(A) is a perspective view of the cylindrical pulp sheet used at a 1st process, (b) is a top view. (A) is a perspective view of a plate-like pulp sheet of another form used in the first step, (b) is a plan view of (a), and (c) is a plan view of a plate-like pulp sheet of another form. . The figure for demonstrating the fibrillation method of a 1st process.

Claims (8)

When the cellulose fiber aggregate is defibrated by putting the cellulose fiber aggregate in a mixer having rotating blades as stirring means and stirring at high speed, a rod-like 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,
A method for producing a cellulose fiber-containing thermoplastic resin composition comprising a step of stirring at low speed while cooling the mixture.   2. The cellulose fiber-containing thermoplastic according to claim 1, wherein the rod-like pulp sheet is a cylindrical one obtained by rolling one or two or more turns of a pulp sheet or a plate-like one obtained by folding a pulp sheet one or more times. A method for producing a resin composition.   The average peripheral speed of the rotating blades during the high-speed stirring is 10 to 100 m / sec, the average peripheral speed of the rotating blades during the low-speed rotation is 1 to 30 m / sec, and the peripheral speed during the high-speed stirring is the low speed The manufacturing method of the cellulose fiber containing thermoplastic resin composition of Claim 1 or 2 larger than the peripheral speed at the time of stirring.   The manufacturing method of the cellulose fiber containing thermoplastic resin composition of any one of Claims 1-3 whose moisture content rate of the said cellulose fiber aggregate is 20 mass% or less.   The manufacturing method of the cellulose fiber containing thermoplastic resin composition of any one of Claims 1-4 whose average fiber length of a cellulose fiber is 0.1-1000 mm. The thermoplastic resin is selected from a crystalline resin having a melting point of 230 ° C. or less and an amorphous resin having a melt viscosity of 10 ² to 10 ⁵ poise (200 ° C., shear rate 100 sec ⁻¹ ) measured with a capillary ohmmeter. The manufacturing method of the cellulose fiber containing thermoplastic resin composition of any one of Claims 1-5 which exists. It is the resin molding obtained from the cellulose fiber containing thermoplastic resin composition obtained by the manufacturing method of any one of Claims 1-6, and is the maximum among the cellulose fiber lumps which exist in the said molding body surface. A resin molded product having a diameter or maximum length of not less than 0.5 mm and the number of cellulose fiber masses is 10/500 cm ² or less. The resin molding of Claim 7 whose density of a molding is 0.4-1.3 g / cm < ³ >.

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