JP2019059956A - Thermoplastic resin composition - Google Patents

Abstract

To provide a thermoplastic resin composition that is relatively inexpensive, does not cause problems associated with thermal recycling, solvent treatment, and the like, and has high strength.SOLUTION: A thermoplastic resin composition (S) contains a thermoplastic resin and a plant fiber as a reinforcement material for the thermoplastic resin. The plant fiber is a cellulose nanofiber that is obtained by atomizing (20) a pulp fiber (P) containing lignin, and has an average fiber diameter of 20-500 nm, a water retention capacity of 350% or less, a sedimentation rate of 0.030 mm/min or less, and a pulp viscosity of 3.5 or more and 4.0 cps or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a thermoplastic resin composition.

  Conventionally, carbon fibers, glass fibers, and the like have been used as reinforcing materials for thermoplastic resins. However, carbon fibers are not suitable for thermal recycling because they are hard to burn, and have the problem of high price. Glass fibers also have the problem of disposal in thermal recycling.

  Therefore, in recent years, researches on technology for using plant fibers which are relatively inexpensive and have no problem of thermal recycling as a reinforcing material for thermoplastic resin have been advanced. Describing this point in detail, plant fibers are not used as artificially synthesized in fiber form like carbon fibers and glass fibers, but are used because they are used by loosening the fibrils possessed by plants. It becomes. With regard to the problem of thermal recycling, carbon fibers and glass fibers remain as ash at the time of incineration, which causes problems such as blockage of pipes in the furnace due to ash and landfill treatment, while plant fibers almost remain as ash. There is no problem such as blockage in the furnace piping and landfill treatment.

  And, at present, it has been proposed to use cellulose nanofibers obtained by processing plant fibers as a reinforcing material for thermoplastic resin. The thermoplastic resin composition using this cellulose nanofiber as a reinforcing material is also said to have equivalent strength at one-fifth the weight of steel.

  In this respect, for example, Patent Documents 1 to 3 disclose techniques for surface modification of cellulose microfibrils to reinforce a thermoplastic resin. However, surface modifiers have the problem of inactivation in water. Also, because the reaction is very slow, it has to be processed under organic solvent, causing problems of solvent processing. That is, when an organic solvent is used, measures for preventing the organic solvent from being scattered in the atmosphere at each process, new installation of a solvent processing facility, etc. become necessary, and the cost rises.

  On the other hand, Patent Document 4 discloses a technique of reinforcing a thermoplastic resin by drying and classifying cellulose fibers, and kneading with a thermoplastic resin. However, since the cellulose fiber is hydrophilic, it has poor bonding at the interface with the hydrophobic thermoplastic resin, and there is a problem that a sufficient reinforcing effect can not be obtained.

JP 2012-229350 A JP, 2012-214563, A Japanese Patent Publication No. 11-513425 Unexamined-Japanese-Patent No. 2010-089483

  The main problem to be solved by the invention is to provide a thermoplastic resin composition which is relatively inexpensive, does not have the problem of thermal recycling, the problem of solvent treatment and the like, and is strong.

The present invention for solving the above problems is as follows.
(Invention according to claim 1)
A thermoplastic resin composition comprising a thermoplastic resin and a plant fiber as a reinforcing material of the thermoplastic resin,
The vegetable fiber has an average fiber diameter of 20 to 500 nm, a water retention of 350% or less, a sedimentation rate of 0.030 mm / min or less, and a pulp viscosity of 3.5, which are obtained by refining pulp fibers containing lignin. More than 4.0 cps cellulose nanofibers,
Thermoplastic resin composition characterized in that.

(Action effect)
When the vegetable fiber used as a raw material is pulp fiber, the thermoplastic resin composition obtained can be made cheap, and the problem of thermal recycling can be avoided. Moreover, there is no need to use surface modifiers, and solvent processing problems can be avoided.

  Since cellulose nanofibers are hydrophilic, they have poor adhesion to thermoplastic resins that are inherently hydrophobic, and tend to have a reinforcing effect, in particular, mechanical strength such as bending strength and the like. However, when the pulp fiber used as the raw material of cellulose nanofiber is pulp fiber containing lignin, cellulose nanofiber will also contain lignin. As a result, the lignin functions as a binder for the cellulose nanofibers and the thermoplastic resin, and the bonding property between them and the strength of the thermoplastic resin composition are further improved.

  Cellulose nanofibers have poor dispersibility in thermoplastic resins. However, cellulose nanofibers containing lignin have lower water retention than cellulose nanofibers not containing lignin, and in particular, when the average fiber diameter is 500 nm or less, freeness, dehydrating property, drying property, in a thermoplastic resin Dispersibility etc. improve. As a result, the strength of the thermoplastic resin composition is also improved. In this respect, when the dewaterability of the cellulose nanofibers is improved, for example, energy and the like can be reduced when the cellulose nanofibers are kneaded with a thermoplastic resin and dehydrated, which is also advantageous in terms of manufacturing cost. However, if the refining treatment is performed until the average fiber diameter is less than 20 nm, the cost for the refining treatment will increase, so the average fiber diameter is preferably 20 nm or more.

  The present inventors finely pulverize LBKP and NBKP containing no lignin and BTMP containing lignin, disperse the obtained cellulose nanofibers in water to make a slurry with a concentration of 2%, and this slurry is subjected to 10000 rpm The test was performed by centrifuging for 10 minutes. As a result, the concentration of cellulose nanofibers obtained by subjecting LBKP and NBKP to a concentration of 7% was obtained, while the concentration of cellulose nanofibers obtained by subjecting a BTMP to a concentration of 15%.

  Further, as described above, when the average fiber diameter is 500 nm or less, dewaterability and the like are improved, but mechanical strength such as bending strength and elastic modulus of the thermoplastic resin composition to be obtained is further improved. The inventors of the present invention have prepared cellulose nanofibers (average fiber diameter 500 nm or less) obtained by finely processing BTMP (average fiber diameter 10 to 50 μm) and BTMP, powder of thermoplastic resin (PP and MAPP), and Instead of the masterbatch method and the solid phase shear method, tests were conducted in which direct twin-screw kneading was performed. As a result, the flexural strength and elastic modulus of the obtained thermoplastic resin composition were BTMP <cellulose nanofibers.

(Invention according to claim 2)
The thermoplastic resin and the cellulose nanofibers are
Blends of relatively low melting point thermoplastic resin and cellulose nanofibers as a substrate for dispersing cellulose nanofibers, and heat having a melting point higher than the relatively low melting point thermoplastic resin added to the blend Plastic resin,
The blending ratio of the thermoplastic resin having a melting point higher than that of the relatively low melting point thermoplastic resin is 100 to 10000 parts by mass with respect to 100 parts by mass of the relatively low melting point thermoplastic resin.
The thermoplastic resin composition according to claim 1.
(Invention according to claim 3)
The thermoplastic resin and the cellulose nanofibers are
It is a kneaded product of dry mixed powder of cellulose nanofiber and thermoplastic resin,
The thermoplastic resin composition according to claim 1.
(Invention according to claim 4)
Pulp fiber containing lignin is mechanical pulp,
And the blending ratio of the mechanical pulp to the total pulp fibers having an average fiber diameter of 20 to 500 nm is 50% by mass or more.
The thermoplastic resin composition according to any one of claims 1 to 3.

(Action effect)
The said effect is reliably acquired as the blend ratio with respect to all the pulp fibers of the pulp fiber which contains lignin is mechanical pulp and whose average fiber diameter is 20-500 nm is 50 mass% or more.

(Invention according to claim 5)
The crystallinity of the cellulose nanofibers is 50 to 70%,
The thermoplastic resin composition according to any one of claims 1 to 4.

(Action effect)
If the degree of crystallinity of the cellulose nanofibers is less than 50%, there is no problem in the compatibility with the thermoplastic resin, but the strength of the fiber itself is reduced, so the strength of the thermoplastic resin composition tends to be inferior.

  On the other hand, if the crystallinity of the cellulose nanofibers exceeds 70%, the proportion of strong hydrogen bonds in the molecule increases and the fibers themselves become rigid, but the compatibility with the thermoplastic resin decreases and the thermoplastic resin composition The strength of the objects tends to be poor.

(Invention according to claim 6)
The peak value in the pseudo particle size distribution curve of the cellulose nanofibers is one peak,
The thermoplastic resin composition according to any one of claims 1 to 5.

(Action effect)
That the peak value in the pseudo | simulation particle size distribution curve of a cellulose nanofiber is one peak means that the uniformity of fiber length and a fiber diameter is high, and drying and dispersion | distribution will advance uniformly. In addition, when the uniformity of the fiber diameter and the fiber length is high, the reinforcing effect of the thermoplastic resin composition is strong, and the uniformity of the reinforcing effect is also improved.

(Invention according to claim 7)
The peak value is 5 to 25 μm,
The thermoplastic resin composition according to claim 6.

(Action effect)
In order to set the peak value of cellulose nanofibers to less than 5 μm, it is necessary to carry out a refining treatment for a long time, which leads to an increase in production cost.

  On the other hand, when the peak value exceeds 25 μm, the refining process is insufficient, and the uniformity of the fiber diameter and the fiber length tends to be poor.

  According to the present invention, the thermoplastic resin composition is relatively inexpensive, does not have the problem of thermal recycling, the problem of solvent treatment and the like, and has a high strength.

It is a flowchart of the manufacturing process of a thermoplastic resin composition.

Hereinafter, modes for carrying out the invention will be described.
The thermoplastic resin composition of the present embodiment contains a thermoplastic resin and cellulose nanofibers which are vegetable fibers, and a compatibilizer is further added.

(Pulp fiber)
Cellulose nanofibers can be obtained by subjecting pulp fibers to micronization (fibrillation). As a fiber used as a raw material, 1 type, or 2 or more types can be selected and used out of plant origin fiber, animal origin fiber, microorganisms origin fiber, etc. However, it is preferable to use at least pulp fiber which is vegetable fiber, and mainly composed of pulp fiber containing lignin such as waste paper pulp (DIP) such as magazine waste paper pulp (MDIP) or newspaper waste paper pulp (NDIP), mechanical pulp It is more preferable to use fibers containing as 50% by mass or more), and it is particularly preferable to use mechanical pulp.

  Cellulose nanofibers obtained from pulp fibers containing no lignin are fine and have a large specific surface area, and have many hydroxyl groups on the surface. Therefore, it has poor drainage and dewatering properties, making it difficult to use as a dispersion described later. In addition, since cellulose nanofibers obtained from pulp fibers have hydrophilicity derived from cellulose, they have poor compatibility with hydrophobic thermoplastic resins and poor dispersibility. On the other hand, since cellulose nanofibers obtained from pulp containing lignin such as mechanical pulp contain lignin having higher hydrophobicity than cellulose, this lignin functions as a binder for cellulose nanofibers and thermoplastic resin, Bondability, compatibility, and further, the strength of the thermoplastic resin composition is improved.

  In this regard, the present inventors examined the water retention of fibers after the refining treatment for hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP) and bleached thermomechanical pulp (BTMP). As a result, it was found that the retention level of LBKP and NBKP significantly increases with miniaturization, while BTMP does not significantly increase the retention level. Therefore, it is difficult to reduce the water retention of cellulose nanofibers to a desired value or less when chemical pulp is used, while it is easy to reduce the water retention of cellulose nanofibers to a desired value or less when mechanical pulp is used. It became clear.

  As mechanical pulp, for example, stone ground pulp (SGP), pressurized stone ground pulp (PGW), refiner ground pulp (RGP), chemi ground pulp (CGP), thermo ground pulp (TGP), ground pulp (GP), One or more selected from thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), refiner mechanical pulp (RMP), etc. can be selected and used.

(Pretreatment process)
Pulp fibers are preferably in a form suitable for micronization, for example, in the form of a powder.

  In addition, the pulp fiber can be subjected to a chemical treatment such as, for example, a phosphate esterification treatment, an acetylation treatment, a cyanoethylation treatment and the like, if necessary.

  Furthermore, it is preferable to beat pulp fibers prior to the refining treatment. If the pulp fibers are beaten, the cellulose nanofibers obtained by micronization become entangled easily. The beating of pulp fibers can be performed using, for example, a beater or the like.

(Micronization process)
Pulp fibers are subjected to a pre-treatment, if necessary, and then subjected to a refining (fibrillation) treatment. By this refining process, pulp fibers are microfibrillated to become cellulose nanofibers.

  The refining process may be, for example, one or more of high-pressure homogenizers, homogenizers such as high-pressure homogenizers, grinders, stone-mill-type friction machines such as grinders, conical refiners, refiners such as disc refiners, various bacteria, etc. It can be done using the means of choice.

  However, it is preferable to carry out the refining treatment using at least one of a grinder that grinds between rotating grinding wheels and a wet atomizing device that refines with a high pressure water flow. As the grinder, for example, a mass colloider manufactured by Masuko Sangyo Co., Ltd. can be used. In addition, as a wet atomization device, for example, Starburst of Sugino Machine Co., Ltd., a jet mill of Jako Corporation, etc. can be used.

  In the above-described micronization treatment, for example, the average fiber diameter, water retention, crystallinity, peak value of pseudo particle size distribution, tentacle test results, sedimentation velocity, pulp viscosity, etc. of the obtained cellulose nanofibers are desired values or It is preferable to carry out evaluation.

  Cellulose nanofibers are fibers made of cellulose and derivatives of cellulose. Normal cellulose nanofibers have strong hydration and can be stably dispersed in water (dispersion state) by hydration in an aqueous medium. In the aqueous medium, a plurality of single fibers constituting cellulose nanofibers may be aggregated to form a fibrous form. The average fiber diameter of ordinary cellulose nanofibers is 4 to 2000 nm. Moreover, average fiber length is 1 to 5000 μm.

(Average fiber diameter)
The average fiber diameter of the cellulose nanofibers is preferably 20 to 500 nm, more preferably 150 to 450 nm, and particularly preferably 200 to 400 nm. When the average fiber diameter is 20 to 500 nm, the compatibility with the thermoplastic resin and the reinforcing effect of the thermoplastic resin composition are excellent. Specifically, if the average fiber diameter is less than 20 nm, excessive mechanical energy is applied to the pulp fiber, and the strength of the fiber itself is reduced. Therefore, it tends to be inferior to the reinforcing effect of a thermoplastic resin composition. In addition, the time for the microfabrication process becomes longer, which leads to an increase in manufacturing cost. On the other hand, when the average fiber diameter exceeds 500 nm, the refining tends to be insufficient and the dispersibility of the fibers tends to be poor. If the dispersibility of the fibers is insufficient, the reinforcing effect of the thermoplastic resin composition tends to be inferior.

  The proportion of single fibers having a diameter of more than 500 nm with respect to all fibers is preferably 70% by mass or less, more preferably 60% by mass or less, and particularly preferably 50% by mass or less. If the ratio of single fibers having a diameter of more than 500 nm is 70% by mass or less, the reinforcing effect of the thermoplastic resin composition is excellent.

  The blending ratio of mechanical pulp to total pulp fibers is preferably 50% by mass or more, more preferably 70% by mass or more, and particularly preferably 90% by mass or more. If the compounding ratio is less than 50% by mass, the water retention of the cellulose nanofibers obtained by micronization does not become sufficiently small, and the filterability, the drying property, the compatibility with the thermoplastic resin, and the like tend to be inferior. In addition, the upper limit of the compounding ratio of mechanical pulp is 100 mass%.

  The above-mentioned average fiber diameter can be arbitrarily adjusted by pulp fiber, a pretreatment process, and a refinement process.

(Average fiber length)
The average fiber length of the cellulose nanofibers is preferably 1 to 5000 μm, more preferably 2 to 4000 μm, and particularly preferably 3 to 3000 μm.

  The above-mentioned average fiber length can be arbitrarily adjusted by pulp fiber, a pretreatment process, and a refinement process.

(Water retention)
The water retention of the cellulose nanofibers is preferably 350% or less, more preferably 300% or less, and particularly preferably 280% or less. If the water retention exceeds 350%, the free flowability, the drying property, and the compatibility with the thermoplastic resin tend to be poor. Moreover, in order to make the reinforcement effect of a thermoplastic resin composition excellent, it is necessary to fully dry cellulose nanofibers and to perform uniform dispersion | distribution to a thermoplastic resin. However, since the cellulose nanofibers have high cohesiveness, they tend to aggregate during drying, kneading with a thermoplastic resin, and the like. Therefore, by making the water retention of the cellulose nanofibers 350% or less, and excellent in the freeness, the drying property, and the compatibility with the thermoplastic resin, the drying treatment, the kneading treatment with the thermoplastic resin, etc. are performed. Cohesion can be suppressed, and the reinforcing effect of the thermoplastic resin composition can be made sufficient.

  The water retention degree can be arbitrarily adjusted by the pulp fiber, the pretreatment process, and the micronization process.

(Degree of crystallinity)
The crystallinity of the cellulose nanofibers is preferably 50% or more, more preferably 55% or more, and particularly preferably 60% or more. If the degree of crystallinity is less than 50%, although the compatibility with the thermoplastic resin is improved, the strength of the fiber itself is reduced, so the reinforcing effect of the thermoplastic resin composition tends to be inferior.

  On the other hand, the crystallinity of the cellulose nanofibers is preferably 70% or less, more preferably 69% or less, and particularly preferably 68% or less. When the degree of crystallinity exceeds 70%, the proportion of strong hydrogen bonds in the molecule increases and the fiber itself becomes rigid, but the compatibility with the thermoplastic resin decreases and the reinforcing effect of the thermoplastic resin composition is inferior Tend. In addition, chemical modification of the cellulose nanofibers tends to be difficult.

  The degree of crystallinity can be arbitrarily adjusted by the pulp fiber, the pretreatment process, and the refining process.

(Peak value)
The peak value in the pseudo particle size distribution curve of cellulose nanofibers is preferably one peak. In the case of one peak, cellulose nanofibers have high uniformity of fiber length and fiber diameter, and excellent drying property. In addition, when the uniformity of the fiber diameter and the fiber length is high, the reinforcing effect of the thermoplastic resin composition is high, and the uniformity of the reinforcing effect is also excellent.

  The peak value of the nanofibers is preferably 5 μm or more, more preferably 7 μm or more, and particularly preferably 9 μm or more. In order to make the peak value less than 5 μm, it is necessary to carry out the refining treatment of cellulose nanofibers for a long time, which leads to an increase in production cost.

  On the other hand, the peak value of cellulose nanofibers is preferably 25 μm or less, more preferably 23 μm or less, and particularly preferably 21 μm or less. When the peak value exceeds 25 μm, the refining is insufficient, and the uniformity of the fiber diameter and the fiber length tends to be inferior.

(Settling speed)
The sedimentation speed of the cellulose nanofibers is preferably 0.030 mm / min or less, more preferably 0.025 mm / min or less, and particularly preferably 0.020 mm / min or less. When the sedimentation rate exceeds 0.030 mm / min, the fibers are too long, and the fibers are aggregated in the thermoplastic resin by hydrogen bonding in the fibers, and the reinforcing effect of the thermoplastic resin composition tends to be inferior. The longer the fiber, the larger the apparent particle size and the higher the sedimentation rate.

(Pulp viscosity)
The pulp viscosity of the cellulose nanofibers is preferably 3.5 cps or more, more preferably 3.6 cps or more. When the dispersion of cellulose nanofibers is kneaded with the thermoplastic resin with a pulp viscosity of less than 3.5 cps, the degree of polymerization of the cellulose nanofibers tends to decrease and the reinforcing effect of the thermoplastic resin composition tends to be inferior .

  The pulp viscosity of the cellulose nanofibers is preferably 4.0 cps or less, more preferably 3.9 cps or less. When the pulp viscosity exceeds 4.0 cps, when the dispersion of cellulose nanofibers is kneaded with the thermoplastic resin, the aggregation of the cellulose nanofibers can not be sufficiently suppressed, and the reinforcing effect of the thermoplastic resin composition tends to be inferior. is there.

(Tentacle test)
In the above-mentioned tentacle test, which is a factor in the progress of micronization treatment, 1 mL of a 2% aqueous solution of cellulose nanofibers is placed on the forefinger, the dispersion is sandwiched between the thumb and forefinger, and the thumb is rotated 20 times. It is a test to visually confirm whether a fibrous material remains between the index finger and the forefinger. In the tentacle test, it is preferable to carry out the refining treatment so that the fibrous material does not remain. In addition, the inventors conducted various tests and examinations, and as a result, according to this tentacle test, it was possible to quickly confirm the progress of the miniaturization process, and to recognize that the manufacturing efficiency could be improved. It reached. In addition, when a fibrous material remains, the uniformity of the fiber diameter or the fiber length tends to be poor.

(Fine fiber)
Cellulose nanofibers include one or more of various types of microfibers such as microfibrillar cellulose, microfibrillar fine fibers, microfibrillated cellulose, microfibrillated cellulose, super microfibrillated cellulose and the like These fibers may also be included. In addition, these fine fibers may be further included, and may be further included.

(Dispersion liquid)
The finely divided cellulose nanofibers are dispersed in an aqueous medium to form a dispersion. It is particularly preferable that the total amount of the aqueous medium is water, but an aqueous medium in which another part is a liquid compatible with water can also be preferably used. As another liquid, lower alcohols having 3 or less carbon atoms can be used.

(Solid content concentration)
The solid content concentration of the dispersion is preferably 1% by mass or more, more preferably 1.5% by mass or more, and particularly preferably 2.0% by mass or more. The solid content concentration of the dispersion is preferably 50% by mass or less, more preferably 40% by mass or less, and particularly preferably 30% by mass or less.

(Type B viscosity)
When the concentration of cellulose nanofibers is 2% (w / w), the B-type viscosity of the dispersion is preferably 1000 cps or less, more preferably 900 cps or less, and particularly preferably 800 cps or less . When the B-type viscosity of the dispersion exceeds 1000 cps, in order to knead the dispersion of cellulose nanofibers and the thermoplastic resin, that is, to disperse the cellulose nanofibers in the thermoplastic resin, a large amount of energy is required. It leads to the increase in manufacturing cost.

  On the other hand, the B-type viscosity of the dispersion is preferably 10 cps or more, more preferably 50 cps or more, and particularly preferably 100 cps or more.

(Thermoplastic resin)
Examples of the thermoplastic resin include polyolefins such as polypropylene (PP) and polyethylene (PE), polyester resins such as aliphatic polyester resin and aromatic polyester resin, polyacrylic resins such as polystyrene, methacrylate and acrylate, polyamide resin, One or more of polycarbonate resins and polyacetal resins can be selected and used.

  However, it is preferable to use at least one of polyolefin and polyester resin. Moreover, as polyolefin, it is preferable to use a polypropylene. Further, as the polyester resin, examples of aliphatic polyester resins include polylactic acid and polycaprolactone, and examples of aromatic polyester resins include polyethylene terephthalate and the like. It is preferable to use a polyester resin having the following (also referred to simply as "biodegradable resin").

  As biodegradable resin, 1 type (s) or 2 or more types can be selected and used from hydroxycarboxylic acid type aliphatic polyester, caprolactone type aliphatic polyester, dibasic acid polyester etc., for example.

  As the hydroxycarboxylic acid-based aliphatic polyester, for example, one or more selected from polymers, copolymers and the like of hydroxycarboxylic acids such as lactic acid, malic acid, glucose acid and 3-hydroxybutyric acid It can be used. However, it is preferable to use lactic acid. As this lactic acid, for example, L-lactic acid, D-lactic acid and the like can be used, and these lactic acids may be used alone or in combination of two or more.

  As a caprolactone type aliphatic polyester, 1 type (s) or 2 or more types can be selected and used, for example from the copolymer of polycaprolactone, polycaprolactone, etc., and the said hydroxycarboxylic acid.

  As a dibasic acid polyester, 1 type (s) or 2 or more types can be selected and used among polybutylene succinate, a polyethylene succinate, a polybutylene adipate etc., for example.

  The biodegradable resin may be used alone or in combination of two or more.

  The thermoplastic resin may contain an inorganic filler. Examples of the inorganic filler include simple substances of metallic elements in Groups I to VIII of the periodic table, such as Fe, Na, K, Cu, Mg, Ca, Zn, Ba, Al, Ti, silicon elements, etc. Examples include oxides, hydroxides, carbonates, sulfates, silicates, sulfites, and various clay minerals comprising these compounds.

  Specifically, for example, barium sulfate, calcium sulfate, magnesium sulfate, sodium sulfate, calcium sulfite, zinc oxide, silica, ground calcium carbonate, light calcium carbonate, aluminum borate, alumina, iron oxide, calcium titanate, hydroxide Aluminium, magnesium hydroxide, calcium hydroxide, sodium hydroxide, magnesium carbonate, calcium silicate, clay wollastonite, glass beads, glass powder, silica sand, vermiculite, quartz powder, diatomaceous earth, white carbon, etc. can be exemplified. .

  Plural inorganic fillers may be contained. In addition, it may be contained in waste paper pulp.

(Other ingredients)
The raw material of the thermoplastic resin composition may be, for example, one or more of an antistatic agent, a flame retardant, an antibacterial agent, a coloring agent, a radical scavenger, a foaming agent, and the like in addition to the compatibilizer described later. It can select and can be added in the range which does not inhibit the effect of this invention.

(Blending ratio)
The blending ratio of the cellulose nanofibers and the thermoplastic resin is preferably 1 part by mass or more and 99 parts by mass or less of the thermoplastic resin, 2 parts by mass or more of the cellulose nanofibers, and 98 parts by mass of the thermoplastic resin The content is more preferably at most parts, particularly preferably at least 3 parts by mass of cellulose nanofibers and at most 97 parts by mass of thermoplastic resin. Moreover, it is preferable that 50 mass parts or less of a cellulose nanofiber and 50 mass parts or more of a thermoplastic resin are preferable, and it is more preferable that a cellulose nanofiber is 40 mass parts or less and a thermoplastic resin is 60 mass parts or more. It is particularly preferable that the nanofibers be 70 parts by mass or less and the thermoplastic resin be 30 parts by mass or more. However, when the blending ratio of the cellulose nanofibers is 3 to 10 parts by mass, the strength of the thermoplastic resin composition, in particular, the strength of flexural strength and flexural modulus can be remarkably improved.

  In addition, the content ratio of the cellulose nanofiber and the thermoplastic resin contained in the thermoplastic resin composition finally obtained becomes the same as the said compounding ratio of a cellulose nanofiber and a thermoplastic resin normally.

(Dehydration and drying process)
Cellulose nanofibers and thermoplastic resin are dewatered and dried. However, it is preferable to carry out dehydration treatment and drying treatment together. By treating both together, a large amount of efficient processing is possible. The dewatering treatment and the drying treatment can be performed in different processes and apparatuses, but can be performed in the same process and apparatus, and it is more efficient to perform them in the same process and apparatus.

  For dehydration and drying, for example, one or more selected from lyophilizer, vacuum dryer, heating dryer, stationary dryer, spray drying, kneader, twin-screw kneader, etc. can do.

  However, for dehydration and drying treatment, it is preferable to select and use one or two or more of a lyophilizer, a kneader, and a twin-screw kneader, and it is preferable to use a lyophilizer or a heat dryer. Particularly preferred.

  In the case of using a lyophilizer, water or t-butanol can be used from the viewpoint of preventing aggregation of cellulose nanofibers. The use of water has the advantage that no solvent treatment problems occur. In addition, using t-butanol has the advantages of enabling processing in a short time, being excellent in energy efficiency, and capable of more reliably preventing aggregation of cellulose nanofibers.

  As a heating dryer, for example, a device that can perform heating and stirring by rotational friction, such as a Banbury mixer, a single-screw or multi-screw kneader, a kneader, a solid-phase shear extruder, a laboplast mill, a planetary stirrer, etc. It is preferable to select and use 1 type, or 2 or more types out of (heating stirrers).

  Dehydration and drying are performed by melting the thermoplastic resin in the “masterbatch method” described later, and are performed without melting the thermoplastic resin in the “solid phase shearing method”, and the thermoplastic resin and cellulose are processed. When the nanofibers are simply kneaded, they may be melted or may not be melted.

  However, in the master batch method and the solid phase shear method, 7 to 15 with a continuous filtration device equipped with a centrifuge and a filter cloth prior to dewatering and drying treatment of the dispersion of cellulose nanofibers with the thermoplastic resin. It is preferable to concentrate to a solid concentration of%. By pre-concentrating, drying, or dehydration and drying time can be shortened.

(Kneading process step)
The cellulose nanofibers and the thermoplastic resin which have been subjected to the dehydration and drying treatment are kneaded.

  For this kneading treatment, for example, one or more selected from single-screw or twin-screw or more multi-screw kneader, mixing roll, kneader, roll mill, Banbury mixer, screw press, disperser etc. can do.

  The temperature of the kneading treatment is not less than the glass transition point of the thermoplastic resin and not more than the melting point, and varies depending on the type of the thermoplastic resin, preferably 80 to 220 ° C., and more preferably 90 to 210 ° C. It is especially preferable to set it as 100-200 degreeC.

  The time for the kneading treatment is preferably 1 to 180 minutes, more preferably 2 to 100 minutes, and particularly preferably 3 to 20 minutes.

(Compatibilizer)
It is preferable to add a compatibilizer to the kneaded cellulose nanofibers and the thermoplastic resin.

  As the compatibilizer, it is preferable to use one having a structure having an acid anhydride group in the side chain of the polymer main chain.

  As the acid anhydride, for example, one or two or more selected from among maleic anhydride, itaconic anhydride, citraconic anhydride, citric anhydride and the like can be selected and used, and maleic anhydride is used. Is preferred.

  The compatibilizer is preferably added in an amount of 0.1 parts by mass or more to 100 parts by mass of the thermoplastic resin, more preferably 0.5 parts by mass or more. It is particularly preferable to add so as to be 0 parts by mass or more. Further, it is preferably added so as to be 10 parts by mass or less, more preferably 8 parts by mass or less, and particularly preferably 5 parts by mass or less. In particular, when the addition amount is 1 to 10 parts by mass, the interaction between the cellulose nanofibers and the thermoplastic resin can be promoted, and the strength, particularly the bending strength, of the obtained thermoplastic resin composition can be improved.

(Master batch method)
Next, referring to FIG. 1, it is a method of using a thermoplastic resin and cellulose nanofibers as raw materials and adding a compatibilizer to produce a thermoplastic resin composition, but the strength of the obtained thermoplastic resin composition Will be described (hereinafter also referred to simply as "master batch method").

  In this masterbatch method, first, pulp fibers (P) are pretreated (10) as necessary, and then micronized (20) to obtain cellulose nanofibers, and the cellulose nanofibers are mixed with water (W) Mix to make a dispersion (C). Next, the dispersion (C) and a thermoplastic resin, preferably a low melting point thermoplastic resin (Rx), are subjected to dehydration and drying treatment (30x) and primary kneading treatment (40x). Then, a thermoplastic resin (Ry) and a compatibilizer (Rz) are further added to the primary kneaded product, and a secondary kneading process (50x) and a forming process (60) are performed to obtain a thermoplastic resin composition (S). .

The reason why the thermoplastic resin (Ry) is added (blended) to the primary kneaded material separately from the low melting point thermoplastic resin (Rx) is as follows.
That is, the low melting point thermoplastic resin (Rx) plays a role as a substrate for dispersing nanofibers. In addition, the primary kneaded product in which the low melting point thermoplastic resin (Rx) and the nanofibers are combined plays a role as a so-called master batch for the purpose of coloring, reinforcement and the like. Then, by kneading the masterbatch and the thermoplastic resin (Ry) so as to obtain a desired compounding ratio, it is possible to obtain a targeted thermoplastic resin composition.

  The blending ratio of the thermoplastic resin (Ry) is preferably 100 to 10000 parts by mass with respect to 100 parts by mass of the low melting point thermoplastic resin (Rx) on a mass basis, and more preferably 200 to 10000 parts by mass. Preferably, it is particularly preferably 300 to 10,000 parts by mass.

  This masterbatch method has one feature in that it melts a thermoplastic resin such as a low melting point thermoplastic resin (Rx) during dehydration / drying treatment (30x) and primary kneading treatment (40x).

  In the master batch method, the temperature of the dehydration / drying treatment (30x) is appropriately set according to the type of thermoplastic resin. For example, when using a low melting point polypropylene (melting point 90 ° C.) which is a low melting point thermoplastic resin (Rx) as a thermoplastic resin, it is preferably 90 to 130 ° C., more preferably 90 to 120 ° C. And 90 to 110 ° C. are particularly preferable.

  Further, the time of dehydration / drying treatment (30x) is preferably 80 to 1200 minutes, more preferably 90 to 1100 minutes, and particularly preferably 100 to 1000 minutes.

  Furthermore, as an apparatus for dehydration / drying treatment (30x), for example, a kneader, a multi-axial kneader having one or more screws, a mixing roll, a kneader, a roll mill, a Banbury mixer, a Henschel mixer, a screw press, a disperser, etc. One or two or more of them can be selected and used from among the devices that can shorten the drying time, such as a pressure reduction kneader.

  The temperature of the primary kneading treatment (40x) is also appropriately set according to the type of thermoplastic resin. For example, when using a low melting point polypropylene (melting point 90 ° C.) which is a low melting point thermoplastic resin (Rx) as a thermoplastic resin, it is preferably 90 to 130 ° C., more preferably 90 to 120 ° C. And 90 to 110 ° C. are particularly preferable.

  The time of the primary kneading treatment (40x) is preferably 1 to 100 minutes, more preferably 2 to 80 minutes, and particularly preferably 3 to 60 minutes.

  As an apparatus for the primary kneading treatment (40x), for example, a kneader, a multi-axial kneader having one or more screws, a mixing roll, a kneader, a roll mill, a Banbury mixer, a Henschel mixer, a screw press, a disperser, etc. One or two or more of them can be selected and used from among the devices including the machine which can shorten the drying time.

  The secondary kneading treatment (50x) after the addition of the compatibilizer (Rz) is appropriately set in accordance with the type of the thermoplastic resin (Ry) added after the primary kneading treatment (40x). For example, when using a thermoplastic resin which does not have a low melting point as the thermoplastic resin (Ry), for example, polypropylene (melting point 130 ° C.), the temperature is preferably 130 to 220 ° C., more preferably 130 to 215 ° C. Preferably, the temperature is 130 to 210 ° C.

  The time of the secondary kneading treatment (50x) is preferably 1 to 180 minutes, more preferably 2 to 80 minutes, and particularly preferably 3 to 20 minutes.

  The apparatus for the secondary kneading treatment (50x) includes, for example, a kneader, a multi-axial kneader having one or more screws, a mixing roll, a kneader, a roll mill, a Banbury mixer, a Henschel mixer, a screw press, a disperser, etc. One or two or more of them can be selected and used from among kneaders and apparatuses that can shorten the drying time.

  The temperature of the molding treatment (60) is preferably 130 to 220 ° C., more preferably 130 to 210 ° C., and particularly preferably 130 to 200 ° C.

  The time of the molding treatment (60) is preferably 1 to 200 minutes, more preferably 1 to 190 minutes, and particularly preferably 1 to 180 minutes.

  As an apparatus for the molding process, for example, one or more of an injection molding machine, a blow molding machine, a hollow molding machine, a blow molding machine, a compression molding machine, an extrusion molding machine, a vacuum molding machine, a pressure forming machine, etc. Can be selected and used.

(Solid phase shear method)
Next, with reference to FIG. 1, a method (also referred to simply as “solid phase shearing method”) will be described, which is different from the above-mentioned masterbatch method, but the strength of the obtained thermoplastic resin composition is significantly improved.

  In this solid-phase shearing method, first, pulp fibers (P) are pretreated (10) as necessary, and then micronized (20) to obtain cellulose nanofibers, and the cellulose nanofibers are treated with water (W) Mix to give a dispersion (C). Next, the dispersion (C) and the thermoplastic resin (Ry) are dewatered and dried (30y) and subjected to solid-phase shearing (40y). Then, a compatibilizer (Rz) is added to this solid-phase sheared substance, and a kneading process (50y) and a forming process (60) are performed to obtain a thermoplastic resin composition (S).

  This solid-phase shearing method is characterized in that the thermoplastic resin is not melted during the dehydration / drying treatment (30y). Moreover, in this solid-phase shearing method, in the process of dehydration / drying treatment (30y) and solid-phase shearing treatment (40y), cellulose nanofibers are embedded in the thermoplastic resin while being evaporated and dispersed. Ru. This is also characterized in that cellulose nanofibers are scattered in the thermoplastic resin (Ry), and a dry mixed powder of the cellulose nanofibers and the thermoplastic resin can be obtained.

  The temperature at the time of dehydration / drying treatment (30y) is appropriately set according to the type of thermoplastic resin (Ry). For example, when using polypropylene (melting point 130 ° C.) as the thermoplastic resin (Ry), the temperature is preferably 50 to 130 ° C., more preferably 55 to 125 ° C., and 60 to 120 ° C. Particularly preferred.

  The time of the dehydration / drying treatment (30y) is preferably 1 to 300 minutes, more preferably 2 to 270 minutes, and particularly preferably 3 to 240 minutes.

  As an apparatus for dehydration / drying treatment (30y), for example, a simple stirring device, a kneader, a multi-screw kneader with single or two or more screws, a mixing roll, a kneader, a roll mill, a Banbury mixer, a Henschel mixer, a screw press, a disperser 1 type, or 2 or more types can be selected and used from etc. (Including the apparatus which can shorten drying time like a pressure reduction-type kneader).

  The efficiency of the solid phase shear treatment (40y) is better as the area of contact between the cellulose nanofibers and the thermoplastic resin (Ry) is larger, so the shape of the thermoplastic resin (Ry) is a powder having an average particle diameter of 1 to 1000 μm It is preferable to keep the shape.

  The temperature of the solid phase shearing treatment (40y) is also set appropriately according to the type of thermoplastic resin (Ry). For example, when using polypropylene (melting point 130 ° C.) as the thermoplastic resin (Ry), it is preferable to set 50 to 130 ° C. and 55 to 125 ° C. as in the case of dehydration / drying treatment (30 y). Is more preferable, and 60 to 120 ° C. is particularly preferable.

  The duration of the solid phase shearing treatment (40y) is preferably 1 to 180 minutes, more preferably 2 to 170 minutes, and particularly preferably 3 to 160 minutes.

  Examples of the apparatus for solid-phase shear treatment (40y) include a kneader, a multi-axial kneader with one or more screws, a mixing roll, a kneader, a roll mill, a Banbury mixer, a Henschel mixer, a screw press, a disperser, etc. One or two or more of them can be selected and used from among kneaders and apparatuses that can shorten the drying time.

  The kneading treatment (50y) after adding the compatibilizer (Rz) is preferably 130 to 220 ° C., more preferably 130 to 215 ° C., and particularly preferably 130 to 210 ° C.

  The time of the kneading treatment (50y) is preferably 1 to 180 minutes, more preferably 2 to 80 minutes, and particularly preferably 3 to 20 minutes.

  As an apparatus for the kneading treatment (50y), for example, a kneader, a multi-axial kneader having one or more screws, a mixing roll, a kneader, a roll mill, a Banbury mixer, a Henschel mixer, a screw press, a disperser, etc. (pressure reduction type kneader 1) or 2 or more types can be selected and used from among the apparatuses which also can shorten a drying time like these.

  The temperature in the molding treatment (60) is preferably 130 to 220 ° C., more preferably 130 to 210 ° C., and particularly preferably 130 to 200 ° C.

  The time of the molding treatment (60) is preferably 1 to 200 minutes, more preferably 1 to 190 minutes, and particularly preferably 1 to 180 minutes.

  As an apparatus for the molding process (60), for example, one or more of an injection molding machine, a blow molding machine, a hollow molding machine, a blow molding machine, a compression molding machine, an extrusion molding machine, a vacuum molding machine, a pressure forming machine, etc. Two or more types can be selected and used.

(Forming process)
The cellulose nanofibers and the thermoplastic resin (kneaded product) to which the compatibilizer is added are formed into a desired shape after being subjected to the kneading treatment again if necessary.

  In this respect, although the cellulose nanofibers are dispersed in the kneaded product, the molding processability is excellent.

  The size, thickness, shape, and the like of the molding are not particularly limited, and may be, for example, a sheet, a pellet, a powder, a fiber, or the like.

  This molding process can be carried out by a known molding method, for example, by mold molding, injection molding, extrusion molding, hollow molding, foam molding and the like. Alternatively, the kneaded product may be spun into a fiber, and mixed with the above-described plant material or the like to form a mat or board. Blending can be carried out by, for example, a method of co-deposition by air lay.

  This molding process may be carried out following the kneading process as well, once the kneaded material is cooled, and after being chipped using a crusher etc, this chip is used as a molding machine such as an extrusion molding machine or an injection molding machine. It can be done by putting it on.

(Definition of terms, measurement methods, etc.)
The terms in the specification are as follows unless otherwise noted.

(Average fiber diameter)
100 ml of an aqueous dispersion of cellulose nanofibers having a solid concentration of 0.01% by mass is filtered through a Teflon (registered trademark) membrane filter, and solvent substitution is performed once with 100 ml of ethanol and three times with 20 ml of t-butanol. Next, it is lyophilized and osmium coated to make a sample. This sample is observed with an electron microscope SEM image at a magnification of 5000 times, 10000 times or 30000 times depending on the width of the fiber to be constructed. Specifically, two diagonals are drawn on the observation image, and three straight lines passing the intersections of the diagonals are arbitrarily drawn. Furthermore, the width of a total of 100 fibers intersecting with the three straight lines is measured visually. And let the median diameter of a measured value be an average fiber diameter.

(Average fiber length)
The length of each fiber is measured visually as in the case of the above average fiber diameter. The median length of the measurement value is taken as the average fiber length.

(Water retention)
JAPAN TAPPI No. Measure according to 26: 2000.

(Degree of crystallinity)
It is the value measured by the X-ray-diffraction method based on the "X-ray-diffraction analysis general rule" of JIS-K0131 (1996).
In addition, a cellulose nanofiber has an amorphous part and a crystalline part, and crystallinity means the ratio of the crystalline part in the whole cellulose nanofiber.

(Peak value)
Measure in accordance with ISO-13320 (2009). More specifically, a particle size distribution analyzer (a laser diffraction / scattering particle size distribution analyzer manufactured by Seishin Co., Ltd.) is used to examine the volume-based particle size distribution in the aqueous dispersion of cellulose nanofibers. And the mode diameter of a cellulose nanofiber is measured from this distribution. This mode diameter is taken as a peak value.

(Settling speed)
The aqueous dispersion of cellulose nanofibers having a solid content concentration of 0.1% is measured in accordance with JIS Z 8822.

(Pulp viscosity)
It measures based on JIS-P8215 (1998). The higher the pulp viscosity, the higher the degree of polymerization of cellulose.

(Type B viscosity)
It measures based on "the viscosity measurement method of a liquid" of JIS-Z8803 (2011) about the water dispersion liquid of cellulose nanofiber with 2% of solid content concentration. The B-type viscosity is a resistance torque when the slurry is stirred, and the higher the value, the more energy required for the stirring.

(Including lignin, not including)
The term “including lignin” means that lignin affects the effects such as the improvement in compatibility and the increase in reinforcing effect. Specifically, it means that the Kappa number is 2.0 or more. Therefore, the absence of lignin means that the Kappa number is less than 2.0. When the Kappa number is 20 or more, the compatibility improvement and the reinforcing effect increase become large.

  Preferably, in the range of 30 or more and less than 100, more preferably 50 or more and less than 80, the reinforcing effect becomes larger. However, it should be noted that when the Kappa number is 200 or more, the fluidity at the time of kneading tends to be poor.

(Kappa number)
It is the value measured based on JISP8211: 2011 (pulp-kappa number test method). In addition, it means that lignin content is so large that a numerical value is large.

Next, examples of the present invention will be shown to clarify the effects of the present invention.
Example 1
(Dispersion liquid)
First, 23 L of a 2% by mass aqueous dispersion of bleached mechanical pulp for paper production (BTMP) was beaten using a Niagara beater to a freeness of 100 ml or less. Next, use a grinder (Mascolloider from Masuko Sangyo Co., Ltd.) to perform 3 passes of the refinement process of BTMP, 2 to 3 mass% cellulose with a particle size distribution peak value of 5 to 25 μm and water retention of 200 to 280% A nanofiber slurry was obtained. The slurry was treated with a centrifugal separator at 9000 rpm for 10 minutes to obtain a dispersion of 7 to 15% by mass of cellulose nanofibers.

(Master Badge)
A low melting point polypropylene (Elmodu S901 manufactured by Idemitsu Kosan Co., Ltd., melting point about 80 ° C.) was put into a kneader (Labor Plastomill manufactured by Toyo Seiki Co., Ltd.) adjusted to 105 ° C. and melted. Subsequently, the dispersion liquid of the said 7-15 mass% cellulose nanofiber was gradually thrown in so that the dry mass ratio of low melting point polypropylene and a cellulose nanofiber might be set to 50:50, and water | moisture content was blown off. After the addition of the dispersion was completed, the dispersion was dried and dispersed at 80 rpm for 20 minutes to obtain a 50% cellulose nanofiber blended master batch. This masterbatch was cut into a cylindrical shape of 2 mm in diameter and 2 mm in length using a pelleter to obtain pellets easy to be fed into a twin-screw kneader.

(Kneading process)
Pellets of polypropylene (Novatec PP injection molding grade MA3 manufactured by Japan Polypropylene, melting point: 158 ° C), pellets of the above masterbatch, pellets of maleic acid-modified polypropylene as compatibilizer (Yumex 1010, manufactured by Sanyo Chemical Industries, Ltd.) The mixture was poured into a 500 ml beaker such that the ratio of 80: 20: 1 was achieved. The pellet mixture was kneaded at 45 rpm with a twin-screw kneader prepared at 180 ° C. to obtain 10 mass% cellulose nanofiber blended polypropylene. The polypropylene was cut into a cylindrical shape of 2 mm in diameter and 2 mm in length by a pelleter to obtain a pellet of cellulose nanofiber mixed with 10% by mass of polypropylene.

(Forming process)
Dumbbell-shaped test pieces (grip distance 20 mm, width 3.9 mm, thickness 1.97 mm) and rectangular solid test pieces (length 59 mm, width 9.6 mm) , 3.8 mm thick) and injection molded.

(Example 2)
(Dispersion liquid)
In the same manner as in Example 1, a dispersion of cellulose nanofibers was obtained.

(Solid phase shear object)
Polypropylene powder (Novatec PP injection molding grade MA3 manufactured by Japan Polypropylene, particle size about 500 μm, melting point 158 ° C.), 500 ml of the dispersion liquid of the above 7 to 15 mass% cellulose nanofiber slurry so that the dry mass ratio becomes 90: 5 The mixture was charged into a beaker and stirred at 300 ° C. and 300 rpm for 2 hours using a propeller-type heating stirrer. The mixture is dried to a moisture content of 5 to 10% by this stirring and then subjected to solid-phase shear treatment at 60 rpm for 1 hour with a kneader (Laboplast Mill manufactured by Toyo Seiki Co., Ltd.) adjusted to 70 ° C. to obtain a dry mixed powder of cellulose nanofibers and polypropylene A solid-phase shear product was obtained.

(Kneading process)
The above solid-phase shear product and maleic acid-modified polypropylene powder (Kayaburi manufactured by Kayaku Akzo) as a compatibilizer were charged into a 500 ml beaker so that the dry mass ratio would be 95: 5 and mixed. The mixed powder was kneaded at 45 rpm with a twin-screw kneader prepared at 180 ° C. to obtain a 5% by mass cellulose nanofiber blended polypropylene. The polypropylene was cut into a cylindrical shape of 2 mm in diameter and 2 mm in length by a pelleter to obtain pellets of polypropylene containing 5% by mass of cellulose nanofibers.

(Forming process)
Dumbbell-shaped test piece (20 mm distance between grips, width 3.9 mm, thickness 1.97 mm) and rectangular solid test piece (length 59 mm, width 9.6 mm) , 3.8 mm thick) and injection molded.

(Example 3)
(Dispersion liquid)
In the same manner as in Example 1, a dispersion of cellulose nanofibers was obtained.

(Mixed powder)
Polypropylene powder (Novatec PP injection molding grade MA3 manufactured by Japan Polypropylene, particle size about 500 μm, melting point 158 ° C.), 500 ml of the dispersion liquid of the above 7 to 15 mass% cellulose nanofiber slurry so that the dry mass ratio becomes 90: 5 The mixture was charged into a beaker and stirred at 300 ° C. and 300 rpm for 2 hours using a propeller-type heating stirrer. After being dried to a moisture content of 5 to 10% by this stirring, it is dried in a thermostatic dryer adjusted to 105 ° C. for 24 hours, and a dry mixed powder of cellulose nanofibers and polypropylene (this powder is not a solid-phase shear product). Got).

(Kneading process)
The above mixed powder and a maleic acid-modified polypropylene powder (Kayaburi manufactured by Kayaku Akzo) as a compatibilizer were charged into a 500 ml beaker so that the dry mass ratio was 95: 5 and mixed. The mixed powder was kneaded at 45 rpm with a twin-screw kneader prepared at 180 ° C. to obtain a 5% by mass cellulose nanofiber blended polypropylene. The polypropylene was cut into a cylindrical shape of 2 mm in diameter and 2 mm in length by a pelleter to obtain pellets of polypropylene containing 5% by mass of cellulose nanofibers.

(Forming process)
Dumbbell-shaped test piece (20 mm distance between grips, width 3.9 mm, thickness 1.97 mm) and rectangular solid test piece (length 59 mm, width 9.6 mm) , 3.8 mm thick) and injection molded.

(Example 4)
Example 1 was the same as Example 1 except that in place of bleached mechanical pulp for papermaking (BTMP), used paper wastepaper pulp (MDIP) was used.

(Example 5)
Example 2 was the same as Example 2 except that the recycled paper pulp (MDIP) was used instead of bleached mechanical pulp for paper production (BTMP).

(Comparative example 1)
Example 1 was the same as Example 1 except that instead of bleached mechanical pulp for papermaking (BTMP), hardwood bleached kraft pulp for papermaking (LBKP) was used.

(Comparative example 2)
Example 1 was the same as Example 1 except that instead of bleached mechanical pulp for papermaking (BTMP), softwood bleached kraft pulp for papermaking (NBKP) was used.

(Comparative example 3)
The drying process of Example 1 was the same as Example 1 except that a commercially available cellulose nanofiber slurry (commercially available product) was used instead of the dispersion liquid of cellulose nanofibers.

(Comparative example 4)
The drying process of Example 1 was the same as Example 1 except that CNF (cellulose nanofiber slurry) manufactured by Main University was used instead of the dispersion liquid of cellulose nanofibers.

(Comparative example 5)
The drying process of Example 1 was the same as Example 1 except that the dispersion of cellulose nanofibers was replaced with CNC (cellulose nanocrystal slurry) manufactured by Main University.

(Comparative example 6)
Example 2 was the same as Example 2 except that instead of bleached mechanical pulp for papermaking (BTMP), hardwood bleached kraft pulp for papermaking (LBKP) was used.

(Comparative example 7)
Example 2 was the same as Example 2 except that instead of bleached mechanical pulp for papermaking (BTMP), softwood bleached kraft pulp for papermaking (NBKP) was used.

(Comparative example 8)
The drying process of Example 2 was the same as Example 2 except that a commercially available cellulose nanofiber slurry (commercially available product) was used instead of the dispersion liquid of cellulose nanofibers.

(Reference example)
The thermoplastic resin (composition) which consists only of PP is shown.

  The conditions and results are shown in Tables 1 and 2.

(Evaluation method)
The flexural strength, flexural modulus, tensile strength, tensile modulus, Izod impact strength (with a notch), linear thermal expansion coefficient, and dispersibility were evaluated for each of the test pieces. The evaluation method was as follows.

(Bending strength, flexural modulus)
It measured based on JISK7171: 2008 (plastic-how to obtain | require the bending characteristic) about each rectangular parallelepiped test piece. In addition, it means that a bending strength and a bending elastic modulus are strong (high), so that a numerical value is large.

(Tensile strength, tensile modulus)
Each dumbbell-shaped test piece was measured in accordance with JIS K7161: 2014 (plastic-test method for tensile properties). As the numerical value is larger, it means that the tensile strength and the tensile modulus are higher (higher).

(Izod impact strength (notched))
Each rectangular specimen was measured in accordance with JIS K 7110: 1999 (Plastic-Izod Impact Strength Test Method). The notch depth was 2 mm. In addition, it means that impact strength is strong, so that a numerical value is large.

(Linear thermal expansion coefficient)
Each rectangular specimen was measured according to JIS K7197: 2012 (linear expansion coefficient test method by thermomechanical analysis of plastic). Measurement conditions were a compression load method, a temperature rising rate: 5 ° C./min, a temperature range: 30 to 160 ° C., and a measuring machine: a thermomechanical analyzer (Thermo plus EVO II) manufactured by Rigaku Corporation. The smaller the numerical value, the better the dimensional stability.

  As described above, the thermoplastic resin composition of the present invention is stronger than conventional thermoplastic resins (reinforcing effect). Therefore, it can not only be used for the use to which the thermoplastic resin was conventionally used, but can be used also to the use to which the use was compared conventionally by lack of strength.

Specifically, for example, interior materials, exterior materials, structural materials of transportation equipment such as cars, trains, ships, airplanes, etc.
Housings such as PCs, TVs, phones, electrical appliances such as watches, structural materials, internal parts, etc.
Housings such as mobile communication devices such as mobile phones, structural materials, internal parts, etc.
Portable music playback equipment, video playback equipment, printing equipment, copying equipment, sports equipment, office equipment, toys, housings such as sports equipment, structural materials, internal parts, etc.
Interior materials such as buildings, furniture, exterior materials, structural materials, etc.
Office equipment such as stationery, etc.
In addition, packaging bodies, containers such as trays, protective members, partition members, etc.
It can be used as

  Among the above, as an automotive application, an interior material, an instrument panel, an exterior material, etc. can be illustrated. Specifically, for example, door base material, package tray, pillar garnish, switch base, quarter panel, core of armrest, door trim, seat structure, console box, dashboard, various instrument panels, deck trim, bumper, A spoiler, cowling, etc. can be illustrated.

  Moreover, as a building and furniture use, the covering material etc. of various furniture, such as a door covering material, a door structure material, a desk, a chair, a shelf, and a rattan, can be illustrated.

  10: pretreatment, 20: micronization (fibrillation) treatment, 30x, 30y: drying treatment, 40x: (primary) kneading treatment, 40y: solid phase shearing treatment, 50: compatibilizer addition treatment, 60: (secondary ) Kneading, 70: molding, C: dispersion, P: pulp fiber, Rx: low melting point polypropylene, Ry: polypropylene other than low melting point polypropylene, Rz: compatibilizer, W: water.

  The present invention relates to a thermoplastic resin composition.

  Conventionally, carbon fibers, glass fibers, and the like have been used as reinforcing materials for thermoplastic resins. However, carbon fibers are not suitable for thermal recycling because they are hard to burn, and have the problem of high price. Glass fibers also have the problem of disposal in thermal recycling.

  Therefore, in recent years, researches on technology for using plant fibers which are relatively inexpensive and have no problem of thermal recycling as a reinforcing material for thermoplastic resin have been advanced. Describing this point in detail, plant fibers are not used as artificially synthesized in fiber form like carbon fibers and glass fibers, but are used because they are used by loosening the fibrils possessed by plants. It becomes. With regard to the problem of thermal recycling, carbon fibers and glass fibers remain as ash at the time of incineration, which causes problems such as blockage of pipes in the furnace due to ash and landfill treatment, while plant fibers almost remain as ash. There is no problem such as blockage in the furnace piping and landfill treatment.

  And, at present, it has been proposed to use cellulose nanofibers obtained by processing plant fibers as a reinforcing material for thermoplastic resin. The thermoplastic resin composition using this cellulose nanofiber as a reinforcing material is also said to have equivalent strength at one-fifth the weight of steel.

  In this respect, for example, Patent Documents 1 to 3 disclose techniques for surface modification of cellulose microfibrils to reinforce a thermoplastic resin. However, surface modifiers have the problem of inactivation in water. Also, because the reaction is very slow, it has to be processed under organic solvent, causing problems of solvent processing. That is, when an organic solvent is used, measures for preventing the organic solvent from being scattered in the atmosphere at each process, new installation of a solvent processing facility, etc. become necessary, and the cost rises.

  On the other hand, Patent Document 4 discloses a technique of reinforcing a thermoplastic resin by drying and classifying cellulose fibers, and kneading with a thermoplastic resin. However, since the cellulose fiber is hydrophilic, it has poor bonding at the interface with the hydrophobic thermoplastic resin, and there is a problem that a sufficient reinforcing effect can not be obtained.

JP 2012-229350 A JP, 2012-214563, A Japanese Patent Publication No. 11-513425 Unexamined-Japanese-Patent No. 2010-089483

  The main problem to be solved by the invention is to provide a thermoplastic resin composition which is relatively inexpensive, does not have the problem of thermal recycling, the problem of solvent treatment and the like, and is strong.

The present invention for solving the above problems is as follows.
(Invention according to claim 1)
A thermoplastic resin composition comprising a thermoplastic resin and a plant fiber as a reinforcing material of the thermoplastic resin,
Wherein the plant fibers, an average fiber diameter of 20~500nm the pulp fibers obtained by the process miniaturization, sedimentation rate is a cellulose nanofiber under 0.030 mm / min or more,
Thermoplastic resin composition characterized in that.
(Invention according to claim 2)
The pulp fiber has a kappa number of 2.0 or more and less than 200, which is measured in accordance with JIS P8211.
The thermoplastic resin composition according to claim 1.
(Invention according to claim 3)
The water retention of the cellulose nanofibers is 350% or less
The thermoplastic resin composition according to claim 1 or 2.
(Invention according to claim 4)
The average fiber length of the cellulose nanofibers is 1 to 5000 μm,
The thermoplastic resin composition according to any one of claims 1 to 3.
(Invention according to claim 5)
The ratio of single fibers having a diameter of greater than 500 nm to the pulp fibers is 70% by mass or less,
The thermoplastic resin composition according to any one of claims 1 to 4.

( Main effects)
When the vegetable fiber used as a raw material is pulp fiber, the thermoplastic resin composition obtained can be made cheap, and the problem of thermal recycling can be avoided. Moreover, there is no need to use surface modifiers, and solvent processing problems can be avoided.

  Since cellulose nanofibers are hydrophilic, they have poor adhesion to thermoplastic resins that are inherently hydrophobic, and tend to have a reinforcing effect, in particular, mechanical strength such as bending strength and the like. However, when the pulp fiber used as the raw material of cellulose nanofiber is pulp fiber containing lignin, cellulose nanofiber will also contain lignin. As a result, the lignin functions as a binder for the cellulose nanofibers and the thermoplastic resin, and the bonding property between them and the strength of the thermoplastic resin composition are further improved.

  Cellulose nanofibers have poor dispersibility in thermoplastic resins. However, cellulose nanofibers containing lignin have lower water retention than cellulose nanofibers not containing lignin, and in particular, when the average fiber diameter is 500 nm or less, freeness, dehydrating property, drying property, in a thermoplastic resin Dispersibility etc. improve. As a result, the strength of the thermoplastic resin composition is also improved. In this respect, when the dewaterability of the cellulose nanofibers is improved, for example, energy and the like can be reduced when the cellulose nanofibers are kneaded with a thermoplastic resin and dehydrated, which is also advantageous in terms of manufacturing cost. However, if the refining treatment is performed until the average fiber diameter is less than 20 nm, the cost for the refining treatment will increase, so the average fiber diameter is preferably 20 nm or more.

  The present inventors finely pulverize LBKP and NBKP containing no lignin and BTMP containing lignin, disperse the obtained cellulose nanofibers in water to make a slurry with a concentration of 2%, and this slurry is subjected to 10000 rpm The test was performed by centrifuging for 10 minutes. As a result, the concentration of cellulose nanofibers obtained by subjecting LBKP and NBKP to a concentration of 7% was obtained, while the concentration of cellulose nanofibers obtained by subjecting a BTMP to a concentration of 15%.

  Further, as described above, when the average fiber diameter is 500 nm or less, dewaterability and the like are improved, but mechanical strength such as bending strength and elastic modulus of the thermoplastic resin composition to be obtained is further improved. The inventors of the present invention have prepared cellulose nanofibers (average fiber diameter 500 nm or less) obtained by finely processing BTMP (average fiber diameter 10 to 50 μm) and BTMP, powder of thermoplastic resin (PP and MAPP), and Instead of the masterbatch method and the solid phase shear method, tests were conducted in which direct twin-screw kneading was performed. As a result, the flexural strength and elastic modulus of the obtained thermoplastic resin composition were BTMP <cellulose nanofibers.

  The said effect is reliably acquired as the blend ratio with respect to all the pulp fibers of the pulp fiber which contains lignin is mechanical pulp and whose average fiber diameter is 20-500 nm is 50 mass% or more.

  If the degree of crystallinity of the cellulose nanofibers is less than 50%, there is no problem in the compatibility with the thermoplastic resin, but the strength of the fiber itself is reduced, so the strength of the thermoplastic resin composition tends to be inferior.

  On the other hand, if the crystallinity of the cellulose nanofibers exceeds 70%, the proportion of strong hydrogen bonds in the molecule increases and the fibers themselves become rigid, but the compatibility with the thermoplastic resin decreases and the thermoplastic resin composition The strength of the objects tends to be poor.

  That the peak value in the pseudo | simulation particle size distribution curve of a cellulose nanofiber is one peak means that the uniformity of fiber length and a fiber diameter is high, and drying and dispersion | distribution will advance uniformly. In addition, when the uniformity of the fiber diameter and the fiber length is high, the reinforcing effect of the thermoplastic resin composition is strong, and the uniformity of the reinforcing effect is also improved.

  In order to set the peak value of cellulose nanofibers to less than 5 μm, it is necessary to carry out a refining treatment for a long time, which leads to an increase in production cost.

  On the other hand, when the peak value exceeds 25 μm, the refining process is insufficient, and the uniformity of the fiber diameter and the fiber length tends to be poor.

  According to the present invention, the thermoplastic resin composition is relatively inexpensive, does not have the problem of thermal recycling, the problem of solvent treatment and the like, and has a high strength.

It is a flowchart of the manufacturing process of a thermoplastic resin composition.

Hereinafter, modes for carrying out the invention will be described.
The thermoplastic resin composition of the present embodiment contains a thermoplastic resin and cellulose nanofibers which are vegetable fibers, and a compatibilizer is further added.

(Pulp fiber)
Cellulose nanofibers can be obtained by subjecting pulp fibers to micronization (fibrillation). As a fiber used as a raw material, 1 type, or 2 or more types can be selected and used out of plant origin fiber, animal origin fiber, microorganisms origin fiber, etc. However, it is preferable to use at least pulp fiber which is vegetable fiber, and mainly composed of pulp fiber containing lignin such as waste paper pulp (DIP) such as magazine waste paper pulp (MDIP) or newspaper waste paper pulp (NDIP), mechanical pulp It is more preferable to use fibers containing as 50% by mass or more), and it is particularly preferable to use mechanical pulp.

  Cellulose nanofibers obtained from pulp fibers containing no lignin are fine and have a large specific surface area, and have many hydroxyl groups on the surface. Therefore, it has poor drainage and dewatering properties, making it difficult to use as a dispersion described later. In addition, since cellulose nanofibers obtained from pulp fibers have hydrophilicity derived from cellulose, they have poor compatibility with hydrophobic thermoplastic resins and poor dispersibility. On the other hand, since cellulose nanofibers obtained from pulp containing lignin such as mechanical pulp contain lignin having higher hydrophobicity than cellulose, this lignin functions as a binder for cellulose nanofibers and thermoplastic resin, Bondability, compatibility, and further, the strength of the thermoplastic resin composition is improved.

  In this regard, the present inventors examined the water retention of fibers after the refining treatment for hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP) and bleached thermomechanical pulp (BTMP). As a result, it was found that the retention level of LBKP and NBKP significantly increases with miniaturization, while BTMP does not significantly increase the retention level. Therefore, it is difficult to reduce the water retention of cellulose nanofibers to a desired value or less when chemical pulp is used, while it is easy to reduce the water retention of cellulose nanofibers to a desired value or less when mechanical pulp is used. It became clear.

  As mechanical pulp, for example, stone ground pulp (SGP), pressurized stone ground pulp (PGW), refiner ground pulp (RGP), chemi ground pulp (CGP), thermo ground pulp (TGP), ground pulp (GP), One or more selected from thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), refiner mechanical pulp (RMP), etc. can be selected and used.

(Pretreatment process)
Pulp fibers are preferably in a form suitable for micronization, for example, in the form of a powder.

  In addition, the pulp fiber can be subjected to a chemical treatment such as, for example, a phosphate esterification treatment, an acetylation treatment, a cyanoethylation treatment and the like, if necessary.

  Furthermore, it is preferable to beat pulp fibers prior to the refining treatment. If the pulp fibers are beaten, the cellulose nanofibers obtained by micronization become entangled easily. The beating of pulp fibers can be performed using, for example, a beater or the like.

(Micronization process)
Pulp fibers are subjected to a pre-treatment, if necessary, and then subjected to a refining (fibrillation) treatment. By this refining process, pulp fibers are microfibrillated to become cellulose nanofibers.

  The refining process may be, for example, one or more of high-pressure homogenizers, homogenizers such as high-pressure homogenizers, grinders, stone-mill-type friction machines such as grinders, conical refiners, refiners such as disc refiners, various bacteria, etc. It can be done using the means of choice.

  However, it is preferable to carry out the refining treatment using at least one of a grinder that grinds between rotating grinding wheels and a wet atomizing device that refines with a high pressure water flow. As the grinder, for example, a mass colloider manufactured by Masuko Sangyo Co., Ltd. can be used. In addition, as a wet atomization device, for example, Starburst of Sugino Machine Co., Ltd., a jet mill of Jako Corporation, etc. can be used.

  In the above-described micronization treatment, for example, the average fiber diameter, water retention, crystallinity, peak value of pseudo particle size distribution, tentacle test results, sedimentation velocity, pulp viscosity, etc. of the obtained cellulose nanofibers are desired values or It is preferable to carry out evaluation.

  Cellulose nanofibers are fibers made of cellulose and derivatives of cellulose. Normal cellulose nanofibers have strong hydration and can be stably dispersed in water (dispersion state) by hydration in an aqueous medium. In the aqueous medium, a plurality of single fibers constituting cellulose nanofibers may be aggregated to form a fibrous form. The average fiber diameter of ordinary cellulose nanofibers is 4 to 2000 nm. Moreover, average fiber length is 1 to 5000 μm.

(Average fiber diameter)
The average fiber diameter of the cellulose nanofibers is preferably 20 to 500 nm, more preferably 150 to 450 nm, and particularly preferably 200 to 400 nm. When the average fiber diameter is 20 to 500 nm, the compatibility with the thermoplastic resin and the reinforcing effect of the thermoplastic resin composition are excellent. Specifically, if the average fiber diameter is less than 20 nm, excessive mechanical energy is applied to the pulp fiber, and the strength of the fiber itself is reduced. Therefore, it tends to be inferior to the reinforcing effect of a thermoplastic resin composition. In addition, the time for the microfabrication process becomes longer, which leads to an increase in manufacturing cost. On the other hand, when the average fiber diameter exceeds 500 nm, the refining tends to be insufficient and the dispersibility of the fibers tends to be poor. If the dispersibility of the fibers is insufficient, the reinforcing effect of the thermoplastic resin composition tends to be inferior.

  The proportion of single fibers having a diameter of more than 500 nm with respect to all fibers is preferably 70% by mass or less, more preferably 60% by mass or less, and particularly preferably 50% by mass or less. If the ratio of single fibers having a diameter of more than 500 nm is 70% by mass or less, the reinforcing effect of the thermoplastic resin composition is excellent.

  The blending ratio of mechanical pulp to total pulp fibers is preferably 50% by mass or more, more preferably 70% by mass or more, and particularly preferably 90% by mass or more. If the compounding ratio is less than 50% by mass, the water retention of the cellulose nanofibers obtained by micronization does not become sufficiently small, and the filterability, the drying property, the compatibility with the thermoplastic resin, and the like tend to be inferior. In addition, the upper limit of the compounding ratio of mechanical pulp is 100 mass%.

  The above-mentioned average fiber diameter can be arbitrarily adjusted by pulp fiber, a pretreatment process, and a refinement process.

(Average fiber length)
The average fiber length of the cellulose nanofibers is preferably 1 to 5000 μm, more preferably 2 to 4000 μm, and particularly preferably 3 to 3000 μm.

  The above-mentioned average fiber length can be arbitrarily adjusted by pulp fiber, a pretreatment process, and a refinement process.

(Water retention)
The water retention of the cellulose nanofibers is preferably 350% or less, more preferably 300% or less, and particularly preferably 280% or less. If the water retention exceeds 350%, the free flowability, the drying property, and the compatibility with the thermoplastic resin tend to be poor. Moreover, in order to make the reinforcement effect of a thermoplastic resin composition excellent, it is necessary to fully dry cellulose nanofibers and to perform uniform dispersion | distribution to a thermoplastic resin. However, since the cellulose nanofibers have high cohesiveness, they tend to aggregate during drying, kneading with a thermoplastic resin, and the like. Therefore, by making the water retention of the cellulose nanofibers 350% or less, and excellent in the freeness, the drying property, and the compatibility with the thermoplastic resin, the drying treatment, the kneading treatment with the thermoplastic resin, etc. are performed. Cohesion can be suppressed, and the reinforcing effect of the thermoplastic resin composition can be made sufficient.

  The water retention degree can be arbitrarily adjusted by the pulp fiber, the pretreatment process, and the micronization process.

(Degree of crystallinity)
The crystallinity of the cellulose nanofibers is preferably 50% or more, more preferably 55% or more, and particularly preferably 60% or more. If the degree of crystallinity is less than 50%, although the compatibility with the thermoplastic resin is improved, the strength of the fiber itself is reduced, so the reinforcing effect of the thermoplastic resin composition tends to be inferior.

  On the other hand, the crystallinity of the cellulose nanofibers is preferably 70% or less, more preferably 69% or less, and particularly preferably 68% or less. When the degree of crystallinity exceeds 70%, the proportion of strong hydrogen bonds in the molecule increases and the fiber itself becomes rigid, but the compatibility with the thermoplastic resin decreases and the reinforcing effect of the thermoplastic resin composition is inferior Tend. In addition, chemical modification of the cellulose nanofibers tends to be difficult.

  The degree of crystallinity can be arbitrarily adjusted by the pulp fiber, the pretreatment process, and the refining process.

(Peak value)
The peak value in the pseudo particle size distribution curve of cellulose nanofibers is preferably one peak. In the case of one peak, cellulose nanofibers have high uniformity of fiber length and fiber diameter, and excellent drying property. In addition, when the uniformity of the fiber diameter and the fiber length is high, the reinforcing effect of the thermoplastic resin composition is high, and the uniformity of the reinforcing effect is also excellent.

  The peak value of the nanofibers is preferably 5 μm or more, more preferably 7 μm or more, and particularly preferably 9 μm or more. In order to make the peak value less than 5 μm, it is necessary to carry out the refining treatment of cellulose nanofibers for a long time, which leads to an increase in production cost.

  On the other hand, the peak value of cellulose nanofibers is preferably 25 μm or less, more preferably 23 μm or less, and particularly preferably 21 μm or less. When the peak value exceeds 25 μm, the refining is insufficient, and the uniformity of the fiber diameter and the fiber length tends to be inferior.

(Settling speed)
The sedimentation speed of the cellulose nanofibers is preferably 0.030 mm / min or less, more preferably 0.025 mm / min or less, and particularly preferably 0.020 mm / min or less. When the sedimentation rate exceeds 0.030 mm / min, the fibers are too long, and the fibers are aggregated in the thermoplastic resin by hydrogen bonding in the fibers, and the reinforcing effect of the thermoplastic resin composition tends to be inferior. The longer the fiber, the larger the apparent particle size and the higher the sedimentation rate.

(Pulp viscosity)
The pulp viscosity of the cellulose nanofibers is preferably 3.5 cps or more, more preferably 3.6 cps or more. When the dispersion of cellulose nanofibers is kneaded with the thermoplastic resin with a pulp viscosity of less than 3.5 cps, the degree of polymerization of the cellulose nanofibers tends to decrease and the reinforcing effect of the thermoplastic resin composition tends to be inferior .

  The pulp viscosity of the cellulose nanofibers is preferably 4.0 cps or less, more preferably 3.9 cps or less. When the pulp viscosity exceeds 4.0 cps, when the dispersion of cellulose nanofibers is kneaded with the thermoplastic resin, the aggregation of the cellulose nanofibers can not be sufficiently suppressed, and the reinforcing effect of the thermoplastic resin composition tends to be inferior. is there.

(Tentacle test)
In the above-mentioned tentacle test, which is a factor in the progress of micronization treatment, 1 mL of a 2% aqueous solution of cellulose nanofibers is placed on the forefinger, the dispersion is sandwiched between the thumb and forefinger, and the thumb is rotated 20 times. It is a test to visually confirm whether a fibrous material remains between the index finger and the forefinger. In the tentacle test, it is preferable to carry out the refining treatment so that the fibrous material does not remain. In addition, the inventors conducted various tests and examinations, and as a result, according to this tentacle test, it was possible to quickly confirm the progress of the miniaturization process, and to recognize that the manufacturing efficiency could be improved. It reached. In addition, when a fibrous material remains, the uniformity of the fiber diameter or the fiber length tends to be poor.

(Fine fiber)
Cellulose nanofibers include one or more of various types of microfibers such as microfibrillar cellulose, microfibrillar fine fibers, microfibrillated cellulose, microfibrillated cellulose, super microfibrillated cellulose and the like These fibers may also be included. In addition, these fine fibers may be further included, and may be further included.

(Dispersion liquid)
The finely divided cellulose nanofibers are dispersed in an aqueous medium to form a dispersion. It is particularly preferable that the total amount of the aqueous medium is water, but an aqueous medium in which another part is a liquid compatible with water can also be preferably used. As another liquid, lower alcohols having 3 or less carbon atoms can be used.

(Solid content concentration)
The solid content concentration of the dispersion is preferably 1% by mass or more, more preferably 1.5% by mass or more, and particularly preferably 2.0% by mass or more. The solid content concentration of the dispersion is preferably 50% by mass or less, more preferably 40% by mass or less, and particularly preferably 30% by mass or less.

(Type B viscosity)
When the concentration of cellulose nanofibers is 2% (w / w), the B-type viscosity of the dispersion is preferably 1000 cps or less, more preferably 900 cps or less, and particularly preferably 800 cps or less . When the B-type viscosity of the dispersion exceeds 1000 cps, in order to knead the dispersion of cellulose nanofibers and the thermoplastic resin, that is, to disperse the cellulose nanofibers in the thermoplastic resin, a large amount of energy is required. It leads to the increase in manufacturing cost.

  On the other hand, the B-type viscosity of the dispersion is preferably 10 cps or more, more preferably 50 cps or more, and particularly preferably 100 cps or more.

(Thermoplastic resin)
Examples of the thermoplastic resin include polyolefins such as polypropylene (PP) and polyethylene (PE), polyester resins such as aliphatic polyester resin and aromatic polyester resin, polyacrylic resins such as polystyrene, methacrylate and acrylate, polyamide resin, One or more of polycarbonate resins and polyacetal resins can be selected and used.

  However, it is preferable to use at least one of polyolefin and polyester resin. Moreover, as polyolefin, it is preferable to use a polypropylene. Further, as the polyester resin, examples of aliphatic polyester resins include polylactic acid and polycaprolactone, and examples of aromatic polyester resins include polyethylene terephthalate and the like. It is preferable to use a polyester resin having the following (also referred to simply as "biodegradable resin").

  As biodegradable resin, 1 type (s) or 2 or more types can be selected and used from hydroxycarboxylic acid type aliphatic polyester, caprolactone type aliphatic polyester, dibasic acid polyester etc., for example.

  As the hydroxycarboxylic acid-based aliphatic polyester, for example, one or more selected from polymers, copolymers and the like of hydroxycarboxylic acids such as lactic acid, malic acid, glucose acid and 3-hydroxybutyric acid It can be used. However, it is preferable to use lactic acid. As this lactic acid, for example, L-lactic acid, D-lactic acid and the like can be used, and these lactic acids may be used alone or in combination of two or more.

  As a caprolactone type aliphatic polyester, 1 type (s) or 2 or more types can be selected and used, for example from the copolymer of polycaprolactone, polycaprolactone, etc., and the said hydroxycarboxylic acid.

  As a dibasic acid polyester, 1 type (s) or 2 or more types can be selected and used among polybutylene succinate, a polyethylene succinate, a polybutylene adipate etc., for example.

  The biodegradable resin may be used alone or in combination of two or more.

  The thermoplastic resin may contain an inorganic filler. Examples of the inorganic filler include simple substances of metallic elements in Groups I to VIII of the periodic table, such as Fe, Na, K, Cu, Mg, Ca, Zn, Ba, Al, Ti, silicon elements, etc. Examples include oxides, hydroxides, carbonates, sulfates, silicates, sulfites, and various clay minerals comprising these compounds.

  Specifically, for example, barium sulfate, calcium sulfate, magnesium sulfate, sodium sulfate, calcium sulfite, zinc oxide, silica, ground calcium carbonate, light calcium carbonate, aluminum borate, alumina, iron oxide, calcium titanate, hydroxide Aluminium, magnesium hydroxide, calcium hydroxide, sodium hydroxide, magnesium carbonate, calcium silicate, clay wollastonite, glass beads, glass powder, silica sand, vermiculite, quartz powder, diatomaceous earth, white carbon, etc. can be exemplified. .

  Plural inorganic fillers may be contained. In addition, it may be contained in waste paper pulp.

(Other ingredients)
The raw material of the thermoplastic resin composition may be, for example, one or more of an antistatic agent, a flame retardant, an antibacterial agent, a coloring agent, a radical scavenger, a foaming agent, and the like in addition to the compatibilizer described later. It can select and can be added in the range which does not inhibit the effect of this invention.

(Blending ratio)
The blending ratio of the cellulose nanofibers and the thermoplastic resin is preferably 1 part by mass or more and 99 parts by mass or less of the thermoplastic resin, 2 parts by mass or more of the cellulose nanofibers, and 98 parts by mass of the thermoplastic resin The content is more preferably at most parts, particularly preferably at least 3 parts by mass of cellulose nanofibers and at most 97 parts by mass of thermoplastic resin. Moreover, it is preferable that 50 mass parts or less of a cellulose nanofiber and 50 mass parts or more of a thermoplastic resin are preferable, and it is more preferable that a cellulose nanofiber is 40 mass parts or less and a thermoplastic resin is 60 mass parts or more. It is particularly preferable that the nanofibers be 70 parts by mass or less and the thermoplastic resin be 30 parts by mass or more. However, when the blending ratio of the cellulose nanofibers is 3 to 10 parts by mass, the strength of the thermoplastic resin composition, in particular, the strength of flexural strength and flexural modulus can be remarkably improved.

  In addition, the content ratio of the cellulose nanofiber and the thermoplastic resin contained in the thermoplastic resin composition finally obtained becomes the same as the said compounding ratio of a cellulose nanofiber and a thermoplastic resin normally.

(Dehydration and drying process)
Cellulose nanofibers and thermoplastic resin are dewatered and dried. However, it is preferable to carry out dehydration treatment and drying treatment together. By treating both together, a large amount of efficient processing is possible. The dewatering treatment and the drying treatment can be performed in different processes and apparatuses, but can be performed in the same process and apparatus, and it is more efficient to perform them in the same process and apparatus.

  For dehydration and drying, for example, one or more selected from lyophilizer, vacuum dryer, heating dryer, stationary dryer, spray drying, kneader, twin-screw kneader, etc. can do.

  However, for dehydration and drying treatment, it is preferable to select and use one or two or more of a lyophilizer, a kneader, and a twin-screw kneader, and it is preferable to use a lyophilizer or a heat dryer. Particularly preferred.

  In the case of using a lyophilizer, water or t-butanol can be used from the viewpoint of preventing aggregation of cellulose nanofibers. The use of water has the advantage that no solvent treatment problems occur. In addition, using t-butanol has the advantages of enabling processing in a short time, being excellent in energy efficiency, and capable of more reliably preventing aggregation of cellulose nanofibers.

  As a heating dryer, for example, a device that can perform heating and stirring by rotational friction, such as a Banbury mixer, a single-screw or multi-screw kneader, a kneader, a solid-phase shear extruder, a laboplast mill, a planetary stirrer, etc. It is preferable to select and use 1 type, or 2 or more types out of (heating stirrers).

  Dehydration and drying are performed by melting the thermoplastic resin in the “masterbatch method” described later, and are performed without melting the thermoplastic resin in the “solid phase shearing method”, and the thermoplastic resin and cellulose are processed. When the nanofibers are simply kneaded, they may be melted or may not be melted.

  However, in the master batch method and the solid phase shear method, 7 to 15 with a continuous filtration device equipped with a centrifuge and a filter cloth prior to dewatering and drying treatment of the dispersion of cellulose nanofibers with the thermoplastic resin. It is preferable to concentrate to a solid concentration of%. By pre-concentrating, drying, or dehydration and drying time can be shortened.

(Kneading process step)
The cellulose nanofibers and the thermoplastic resin which have been subjected to the dehydration and drying treatment are kneaded.

  For this kneading treatment, for example, one or more selected from single-screw or twin-screw or more multi-screw kneader, mixing roll, kneader, roll mill, Banbury mixer, screw press, disperser etc. can do.

  The temperature of the kneading treatment is not less than the glass transition point of the thermoplastic resin and not more than the melting point, and varies depending on the type of the thermoplastic resin, preferably 80 to 220 ° C., and more preferably 90 to 210 ° C. It is especially preferable to set it as 100-200 degreeC.

  The time for the kneading treatment is preferably 1 to 180 minutes, more preferably 2 to 100 minutes, and particularly preferably 3 to 20 minutes.

(Compatibilizer)
It is preferable to add a compatibilizer to the kneaded cellulose nanofibers and the thermoplastic resin.

  As the compatibilizer, it is preferable to use one having a structure having an acid anhydride group in the side chain of the polymer main chain.

  As the acid anhydride, for example, one or two or more selected from among maleic anhydride, itaconic anhydride, citraconic anhydride, citric anhydride and the like can be selected and used, and maleic anhydride is used. Is preferred.

  The compatibilizer is preferably added in an amount of 0.1 parts by mass or more to 100 parts by mass of the thermoplastic resin, more preferably 0.5 parts by mass or more. It is particularly preferable to add so as to be 0 parts by mass or more. Further, it is preferably added so as to be 10 parts by mass or less, more preferably 8 parts by mass or less, and particularly preferably 5 parts by mass or less. In particular, when the addition amount is 1 to 10 parts by mass, the interaction between the cellulose nanofibers and the thermoplastic resin can be promoted, and the strength, particularly the bending strength, of the obtained thermoplastic resin composition can be improved.

(Master batch method)
Next, referring to FIG. 1, it is a method of using a thermoplastic resin and cellulose nanofibers as raw materials and adding a compatibilizer to produce a thermoplastic resin composition, but the strength of the obtained thermoplastic resin composition Will be described (hereinafter also referred to simply as "master batch method").

  In this masterbatch method, first, pulp fibers (P) are pretreated (10) as necessary, and then micronized (20) to obtain cellulose nanofibers, and the cellulose nanofibers are mixed with water (W) Mix to make a dispersion (C). Next, the dispersion (C) and a thermoplastic resin, preferably a low melting point thermoplastic resin (Rx), are subjected to dehydration and drying treatment (30x) and primary kneading treatment (40x). Then, a thermoplastic resin (Ry) and a compatibilizer (Rz) are further added to the primary kneaded product, and a secondary kneading process (50x) and a forming process (60) are performed to obtain a thermoplastic resin composition (S). .

The reason why the thermoplastic resin (Ry) is added (blended) to the primary kneaded material separately from the low melting point thermoplastic resin (Rx) is as follows.
That is, the low melting point thermoplastic resin (Rx) plays a role as a substrate for dispersing nanofibers. In addition, the primary kneaded product in which the low melting point thermoplastic resin (Rx) and the nanofibers are combined plays a role as a so-called master batch for the purpose of coloring, reinforcement and the like. Then, by kneading the masterbatch and the thermoplastic resin (Ry) so as to obtain a desired compounding ratio, it is possible to obtain a targeted thermoplastic resin composition.

  The blending ratio of the thermoplastic resin (Ry) is preferably 100 to 10000 parts by mass with respect to 100 parts by mass of the low melting point thermoplastic resin (Rx) on a mass basis, and more preferably 200 to 10000 parts by mass. Preferably, it is particularly preferably 300 to 10,000 parts by mass.

  This masterbatch method has one feature in that it melts a thermoplastic resin such as a low melting point thermoplastic resin (Rx) during dehydration / drying treatment (30x) and primary kneading treatment (40x).

  In the master batch method, the temperature of the dehydration / drying treatment (30x) is appropriately set according to the type of thermoplastic resin. For example, when using a low melting point polypropylene (melting point 90 ° C.) which is a low melting point thermoplastic resin (Rx) as a thermoplastic resin, it is preferably 90 to 130 ° C., more preferably 90 to 120 ° C. And 90 to 110 ° C. are particularly preferable.

  Further, the time of dehydration / drying treatment (30x) is preferably 80 to 1200 minutes, more preferably 90 to 1100 minutes, and particularly preferably 100 to 1000 minutes.

  Furthermore, as an apparatus for dehydration / drying treatment (30x), for example, a kneader, a multi-axial kneader having one or more screws, a mixing roll, a kneader, a roll mill, a Banbury mixer, a Henschel mixer, a screw press, a disperser, etc. One or two or more of them can be selected and used from among the devices that can shorten the drying time, such as a pressure reduction kneader.

  The temperature of the primary kneading treatment (40x) is also appropriately set according to the type of thermoplastic resin. For example, when using a low melting point polypropylene (melting point 90 ° C.) which is a low melting point thermoplastic resin (Rx) as a thermoplastic resin, it is preferably 90 to 130 ° C., more preferably 90 to 120 ° C. And 90 to 110 ° C. are particularly preferable.

  The time of the primary kneading treatment (40x) is preferably 1 to 100 minutes, more preferably 2 to 80 minutes, and particularly preferably 3 to 60 minutes.

  As an apparatus for the primary kneading treatment (40x), for example, a kneader, a multi-axial kneader having one or more screws, a mixing roll, a kneader, a roll mill, a Banbury mixer, a Henschel mixer, a screw press, a disperser, etc. One or two or more of them can be selected and used from among the devices including the machine which can shorten the drying time.

  The secondary kneading treatment (50x) after the addition of the compatibilizer (Rz) is appropriately set in accordance with the type of the thermoplastic resin (Ry) added after the primary kneading treatment (40x). For example, when using a thermoplastic resin which does not have a low melting point as the thermoplastic resin (Ry), for example, polypropylene (melting point 130 ° C.), the temperature is preferably 130 to 220 ° C., more preferably 130 to 215 ° C. Preferably, the temperature is 130 to 210 ° C.

  The time of the secondary kneading treatment (50x) is preferably 1 to 180 minutes, more preferably 2 to 80 minutes, and particularly preferably 3 to 20 minutes.

  The apparatus for the secondary kneading treatment (50x) includes, for example, a kneader, a multi-axial kneader having one or more screws, a mixing roll, a kneader, a roll mill, a Banbury mixer, a Henschel mixer, a screw press, a disperser, etc. One or two or more of them can be selected and used from among kneaders and apparatuses that can shorten the drying time.

  The temperature of the molding treatment (60) is preferably 130 to 220 ° C., more preferably 130 to 210 ° C., and particularly preferably 130 to 200 ° C.

  The time of the molding treatment (60) is preferably 1 to 200 minutes, more preferably 1 to 190 minutes, and particularly preferably 1 to 180 minutes.

  As an apparatus for the molding process, for example, one or more of an injection molding machine, a blow molding machine, a hollow molding machine, a blow molding machine, a compression molding machine, an extrusion molding machine, a vacuum molding machine, a pressure forming machine, etc. Can be selected and used.

(Solid phase shear method)
Next, with reference to FIG. 1, a method (also referred to simply as “solid phase shearing method”) will be described, which is different from the above-mentioned masterbatch method, but the strength of the obtained thermoplastic resin composition is significantly improved.

  In this solid-phase shearing method, first, pulp fibers (P) are pretreated (10) as necessary, and then micronized (20) to obtain cellulose nanofibers, and the cellulose nanofibers are treated with water (W) Mix to give a dispersion (C). Next, the dispersion (C) and the thermoplastic resin (Ry) are dewatered and dried (30y) and subjected to solid-phase shearing (40y). Then, a compatibilizer (Rz) is added to this solid-phase sheared substance, and a kneading process (50y) and a forming process (60) are performed to obtain a thermoplastic resin composition (S).

  This solid-phase shearing method is characterized in that the thermoplastic resin is not melted during the dehydration / drying treatment (30y). Moreover, in this solid-phase shearing method, in the process of dehydration / drying treatment (30y) and solid-phase shearing treatment (40y), cellulose nanofibers are embedded in the thermoplastic resin while being evaporated and dispersed. Ru. This is also characterized in that cellulose nanofibers are scattered in the thermoplastic resin (Ry), and a dry mixed powder of the cellulose nanofibers and the thermoplastic resin can be obtained.

  The temperature at the time of dehydration / drying treatment (30y) is appropriately set according to the type of thermoplastic resin (Ry). For example, when using polypropylene (melting point 130 ° C.) as the thermoplastic resin (Ry), the temperature is preferably 50 to 130 ° C., more preferably 55 to 125 ° C., and 60 to 120 ° C. Particularly preferred.

  The time of the dehydration / drying treatment (30y) is preferably 1 to 300 minutes, more preferably 2 to 270 minutes, and particularly preferably 3 to 240 minutes.

  As an apparatus for dehydration / drying treatment (30y), for example, a simple stirring device, a kneader, a multi-screw kneader with single or two or more screws, a mixing roll, a kneader, a roll mill, a Banbury mixer, a Henschel mixer, a screw press, a disperser 1 type, or 2 or more types can be selected and used from etc. (Including the apparatus which can shorten drying time like a pressure reduction-type kneader).

  The efficiency of the solid phase shear treatment (40y) is better as the area of contact between the cellulose nanofibers and the thermoplastic resin (Ry) is larger, so the shape of the thermoplastic resin (Ry) is a powder having an average particle diameter of 1 to 1000 μm It is preferable to keep the shape.

  The temperature of the solid phase shearing treatment (40y) is also set appropriately according to the type of thermoplastic resin (Ry). For example, when using polypropylene (melting point 130 ° C.) as the thermoplastic resin (Ry), it is preferable to set 50 to 130 ° C. and 55 to 125 ° C. as in the case of dehydration / drying treatment (30 y). Is more preferable, and 60 to 120 ° C. is particularly preferable.

  The duration of the solid phase shearing treatment (40y) is preferably 1 to 180 minutes, more preferably 2 to 170 minutes, and particularly preferably 3 to 160 minutes.

  Examples of the apparatus for solid-phase shear treatment (40y) include a kneader, a multi-axial kneader with one or more screws, a mixing roll, a kneader, a roll mill, a Banbury mixer, a Henschel mixer, a screw press, a disperser, etc. One or two or more of them can be selected and used from among kneaders and apparatuses that can shorten the drying time.

  The kneading treatment (50y) after adding the compatibilizer (Rz) is preferably 130 to 220 ° C., more preferably 130 to 215 ° C., and particularly preferably 130 to 210 ° C.

  The time of the kneading treatment (50y) is preferably 1 to 180 minutes, more preferably 2 to 80 minutes, and particularly preferably 3 to 20 minutes.

  As an apparatus for the kneading treatment (50y), for example, a kneader, a multi-axial kneader having one or more screws, a mixing roll, a kneader, a roll mill, a Banbury mixer, a Henschel mixer, a screw press, a disperser, etc. (pressure reduction type kneader 1) or 2 or more types can be selected and used from among the apparatuses which also can shorten a drying time like these.

  The temperature in the molding treatment (60) is preferably 130 to 220 ° C., more preferably 130 to 210 ° C., and particularly preferably 130 to 200 ° C.

  The time of the molding treatment (60) is preferably 1 to 200 minutes, more preferably 1 to 190 minutes, and particularly preferably 1 to 180 minutes.

  As an apparatus for the molding process (60), for example, one or more of an injection molding machine, a blow molding machine, a hollow molding machine, a blow molding machine, a compression molding machine, an extrusion molding machine, a vacuum molding machine, a pressure forming machine, etc. Two or more types can be selected and used.

(Forming process)
The cellulose nanofibers and the thermoplastic resin (kneaded product) to which the compatibilizer is added are formed into a desired shape after being subjected to the kneading treatment again if necessary.

  In this respect, although the cellulose nanofibers are dispersed in the kneaded product, the molding processability is excellent.

  The size, thickness, shape, and the like of the molding are not particularly limited, and may be, for example, a sheet, a pellet, a powder, a fiber, or the like.

  This molding process can be carried out by a known molding method, for example, by mold molding, injection molding, extrusion molding, hollow molding, foam molding and the like. Alternatively, the kneaded product may be spun into a fiber, and mixed with the above-described plant material or the like to form a mat or board. Blending can be carried out by, for example, a method of co-deposition by air lay.

  This molding process may be carried out following the kneading process as well, once the kneaded material is cooled, and after being chipped using a crusher etc, this chip is used as a molding machine such as an extrusion molding machine or an injection molding machine. It can be done by putting it on.

(Definition of terms, measurement methods, etc.)
The terms in the specification are as follows unless otherwise noted.

(Average fiber diameter)
100 ml of an aqueous dispersion of cellulose nanofibers having a solid concentration of 0.01% by mass is filtered through a Teflon (registered trademark) membrane filter, and solvent substitution is performed once with 100 ml of ethanol and three times with 20 ml of t-butanol. Next, it is lyophilized and osmium coated to make a sample. This sample is observed with an electron microscope SEM image at a magnification of 5000 times, 10000 times or 30000 times depending on the width of the fiber to be constructed. Specifically, two diagonals are drawn on the observation image, and three straight lines passing the intersections of the diagonals are arbitrarily drawn. Furthermore, the width of a total of 100 fibers intersecting with the three straight lines is measured visually. And let the median diameter of a measured value be an average fiber diameter.

(Average fiber length)
The length of each fiber is measured visually as in the case of the above average fiber diameter. The median length of the measurement value is taken as the average fiber length.

(Water retention)
JAPAN TAPPI No. Measure according to 26: 2000.

(Degree of crystallinity)
It is the value measured by the X-ray-diffraction method based on the "X-ray-diffraction analysis general rule" of JIS-K0131 (1996).
In addition, a cellulose nanofiber has an amorphous part and a crystalline part, and crystallinity means the ratio of the crystalline part in the whole cellulose nanofiber.

(Peak value)
Measure in accordance with ISO-13320 (2009). More specifically, a particle size distribution analyzer (a laser diffraction / scattering particle size distribution analyzer manufactured by Seishin Co., Ltd.) is used to examine the volume-based particle size distribution in the aqueous dispersion of cellulose nanofibers. And the mode diameter of a cellulose nanofiber is measured from this distribution. This mode diameter is taken as a peak value.

(Settling speed)
The aqueous dispersion of cellulose nanofibers having a solid content concentration of 0.1% is measured in accordance with JIS Z 8822.

(Pulp viscosity)
It measures based on JIS-P8215 (1998). The higher the pulp viscosity, the higher the degree of polymerization of cellulose.

(Type B viscosity)
It measures based on "the viscosity measurement method of a liquid" of JIS-Z8803 (2011) about the water dispersion liquid of cellulose nanofiber with 2% of solid content concentration. The B-type viscosity is a resistance torque when the slurry is stirred, and the higher the value, the more energy required for the stirring.

(Including lignin, not including)
The term “including lignin” means that lignin affects the effects such as the improvement in compatibility and the increase in reinforcing effect. Specifically, it means that the Kappa number is 2.0 or more. Therefore, the absence of lignin means that the Kappa number is less than 2.0. When the Kappa number is 20 or more, the compatibility improvement and the reinforcing effect increase become large.

  Preferably, in the range of 30 or more and less than 100, more preferably 50 or more and less than 80, the reinforcing effect becomes larger. However, it should be noted that when the Kappa number is 200 or more, the fluidity at the time of kneading tends to be poor.

(Kappa number)
It is the value measured based on JISP8211: 2011 (pulp-kappa number test method). In addition, it means that lignin content is so large that a numerical value is large.

Next, examples of the present invention will be shown to clarify the effects of the present invention.
Example 1
(Dispersion liquid)
First, 23 L of a 2% by mass aqueous dispersion of bleached mechanical pulp for paper production (BTMP) was beaten using a Niagara beater to a freeness of 100 ml or less. Next, use a grinder (Mascolloider from Masuko Sangyo Co., Ltd.) to perform 3 passes of the refinement process of BTMP, 2 to 3 mass% cellulose with a particle size distribution peak value of 5 to 25 μm and water retention of 200 to 280% A nanofiber slurry was obtained. The slurry was treated with a centrifugal separator at 9000 rpm for 10 minutes to obtain a dispersion of 7 to 15% by mass of cellulose nanofibers.

(Master Badge)
A low melting point polypropylene (Elmodu S901 manufactured by Idemitsu Kosan Co., Ltd., melting point about 80 ° C.) was put into a kneader (Labor Plastomill manufactured by Toyo Seiki Co., Ltd.) adjusted to 105 ° C. and melted. Subsequently, the dispersion liquid of the said 7-15 mass% cellulose nanofiber was gradually thrown in so that the dry mass ratio of low melting point polypropylene and a cellulose nanofiber might be set to 50:50, and water | moisture content was blown off. After the addition of the dispersion was completed, the dispersion was dried and dispersed at 80 rpm for 20 minutes to obtain a 50% cellulose nanofiber blended master batch. This masterbatch was cut into a cylindrical shape of 2 mm in diameter and 2 mm in length using a pelleter to obtain pellets easy to be fed into a twin-screw kneader.

(Kneading process)
Pellets of polypropylene (Novatec PP injection molding grade MA3 manufactured by Japan Polypropylene, melting point: 158 ° C), pellets of the above masterbatch, pellets of maleic acid-modified polypropylene as compatibilizer (Yumex 1010, manufactured by Sanyo Chemical Industries, Ltd.) The mixture was poured into a 500 ml beaker such that the ratio of 80: 20: 1 was achieved. The pellet mixture was kneaded at 45 rpm with a twin-screw kneader prepared at 180 ° C. to obtain 10 mass% cellulose nanofiber blended polypropylene. The polypropylene was cut into a cylindrical shape of 2 mm in diameter and 2 mm in length by a pelleter to obtain a pellet of cellulose nanofiber mixed with 10% by mass of polypropylene.

(Forming process)
Dumbbell-shaped test pieces (grip distance 20 mm, width 3.9 mm, thickness 1.97 mm) and rectangular solid test pieces (length 59 mm, width 9.6 mm) , 3.8 mm thick) and injection molded.

(Example 2)
(Dispersion liquid)
In the same manner as in Example 1, a dispersion of cellulose nanofibers was obtained.

(Solid phase shear object)
Polypropylene powder (Novatec PP injection molding grade MA3 manufactured by Japan Polypropylene, particle size about 500 μm, melting point 158 ° C.), 500 ml of the dispersion liquid of the above 7 to 15 mass% cellulose nanofiber slurry so that the dry mass ratio becomes 90: 5 The mixture was charged into a beaker and stirred at 300 ° C. and 300 rpm for 2 hours using a propeller-type heating stirrer. The mixture is dried to a moisture content of 5 to 10% by this stirring and then subjected to solid-phase shear treatment at 60 rpm for 1 hour with a kneader (Laboplast Mill manufactured by Toyo Seiki Co., Ltd.) adjusted to 70 ° C. to obtain a dry mixed powder of cellulose nanofibers and polypropylene A solid-phase shear product was obtained.

(Kneading process)
The above solid-phase shear product and maleic acid-modified polypropylene powder (Kayaburi manufactured by Kayaku Akzo) as a compatibilizer were charged into a 500 ml beaker so that the dry mass ratio would be 95: 5 and mixed. The mixed powder was kneaded at 45 rpm with a twin-screw kneader prepared at 180 ° C. to obtain a 5% by mass cellulose nanofiber blended polypropylene. The polypropylene was cut into a cylindrical shape of 2 mm in diameter and 2 mm in length by a pelleter to obtain pellets of polypropylene containing 5% by mass of cellulose nanofibers.

(Forming process)
Dumbbell-shaped test piece (20 mm distance between grips, width 3.9 mm, thickness 1.97 mm) and rectangular solid test piece (length 59 mm, width 9.6 mm) , 3.8 mm thick) and injection molded.

(Example 3)
(Dispersion liquid)
In the same manner as in Example 1, a dispersion of cellulose nanofibers was obtained.

(Mixed powder)
Polypropylene powder (Novatec PP injection molding grade MA3 manufactured by Japan Polypropylene, particle size about 500 μm, melting point 158 ° C.), 500 ml of the dispersion liquid of the above 7 to 15 mass% cellulose nanofiber slurry so that the dry mass ratio becomes 90: 5 The mixture was charged into a beaker and stirred at 300 ° C. and 300 rpm for 2 hours using a propeller-type heating stirrer. After being dried to a moisture content of 5 to 10% by this stirring, it is dried in a thermostatic dryer adjusted to 105 ° C. for 24 hours, and a dry mixed powder of cellulose nanofibers and polypropylene (this powder is not a solid-phase shear product). Got).

(Kneading process)
The above mixed powder and a maleic acid-modified polypropylene powder (Kayaburi manufactured by Kayaku Akzo) as a compatibilizer were charged into a 500 ml beaker so that the dry mass ratio was 95: 5 and mixed. The mixed powder was kneaded at 45 rpm with a twin-screw kneader prepared at 180 ° C. to obtain a 5% by mass cellulose nanofiber blended polypropylene. The polypropylene was cut into a cylindrical shape of 2 mm in diameter and 2 mm in length by a pelleter to obtain pellets of polypropylene containing 5% by mass of cellulose nanofibers.

(Forming process)
Dumbbell-shaped test piece (20 mm distance between grips, width 3.9 mm, thickness 1.97 mm) and rectangular solid test piece (length 59 mm, width 9.6 mm) , 3.8 mm thick) and injection molded.

(Example 4)
Example 1 was the same as Example 1 except that in place of bleached mechanical pulp for papermaking (BTMP), used paper wastepaper pulp (MDIP) was used.

(Example 5)
Example 2 was the same as Example 2 except that the recycled paper pulp (MDIP) was used instead of bleached mechanical pulp for paper production (BTMP).

(Comparative example 1)
Example 1 was the same as Example 1 except that instead of bleached mechanical pulp for papermaking (BTMP), hardwood bleached kraft pulp for papermaking (LBKP) was used.

(Comparative example 2)
Example 1 was the same as Example 1 except that instead of bleached mechanical pulp for papermaking (BTMP), softwood bleached kraft pulp for papermaking (NBKP) was used.

(Comparative example 3)
The drying process of Example 1 was the same as Example 1 except that a commercially available cellulose nanofiber slurry (commercially available product) was used instead of the dispersion liquid of cellulose nanofibers.

(Comparative example 4)
The drying process of Example 1 was the same as Example 1 except that CNF (cellulose nanofiber slurry) manufactured by Main University was used instead of the dispersion liquid of cellulose nanofibers.

(Comparative example 5)
The drying process of Example 1 was the same as Example 1 except that the dispersion of cellulose nanofibers was replaced with CNC (cellulose nanocrystal slurry) manufactured by Main University.

(Comparative example 6)
Example 2 was the same as Example 2 except that instead of bleached mechanical pulp for papermaking (BTMP), hardwood bleached kraft pulp for papermaking (LBKP) was used.

(Comparative example 7)
Example 2 was the same as Example 2 except that instead of bleached mechanical pulp for papermaking (BTMP), softwood bleached kraft pulp for papermaking (NBKP) was used.

(Comparative example 8)
The drying process of Example 2 was the same as Example 2 except that a commercially available cellulose nanofiber slurry (commercially available product) was used instead of the dispersion liquid of cellulose nanofibers.

(Reference example)
The thermoplastic resin (composition) which consists only of PP is shown.

  The conditions and results are shown in Tables 1 and 2.

(Evaluation method)
The flexural strength, flexural modulus, tensile strength, tensile modulus, Izod impact strength (with a notch), linear thermal expansion coefficient, and dispersibility were evaluated for each of the test pieces. The evaluation method was as follows.

(Bending strength, flexural modulus)
It measured based on JISK7171: 2008 (plastic-how to obtain | require the bending characteristic) about each rectangular parallelepiped test piece. In addition, it means that a bending strength and a bending elastic modulus are strong (high), so that a numerical value is large.

(Tensile strength, tensile modulus)
Each dumbbell-shaped test piece was measured in accordance with JIS K7161: 2014 (plastic-test method for tensile properties). As the numerical value is larger, it means that the tensile strength and the tensile modulus are higher (higher).

(Izod impact strength (notched))
Each rectangular specimen was measured in accordance with JIS K 7110: 1999 (Plastic-Izod Impact Strength Test Method). The notch depth was 2 mm. In addition, it means that impact strength is strong, so that a numerical value is large.

(Linear thermal expansion coefficient)
Each rectangular specimen was measured according to JIS K7197: 2012 (linear expansion coefficient test method by thermomechanical analysis of plastic). Measurement conditions were a compression load method, a temperature rising rate: 5 ° C./min, a temperature range: 30 to 160 ° C., and a measuring machine: a thermomechanical analyzer (Thermo plus EVO II) manufactured by Rigaku Corporation. The smaller the numerical value, the better the dimensional stability.

  As described above, the thermoplastic resin composition of the present invention is stronger than conventional thermoplastic resins (reinforcing effect). Therefore, it can not only be used for the use to which the thermoplastic resin was conventionally used, but can be used also to the use to which the use was compared conventionally by lack of strength.

Specifically, for example, interior materials, exterior materials, structural materials of transportation equipment such as cars, trains, ships, airplanes, etc.
Housings such as PCs, TVs, phones, electrical appliances such as watches, structural materials, internal parts, etc.
Housings such as mobile communication devices such as mobile phones, structural materials, internal parts, etc.
Portable music playback equipment, video playback equipment, printing equipment, copying equipment, sports equipment, office equipment, toys, housings such as sports equipment, structural materials, internal parts, etc.
Interior materials such as buildings, furniture, exterior materials, structural materials, etc.
Office equipment such as stationery, etc.
In addition, packaging bodies, containers such as trays, protective members, partition members, etc.
It can be used as

  Among the above, as an automotive application, an interior material, an instrument panel, an exterior material, etc. can be illustrated. Specifically, for example, door base material, package tray, pillar garnish, switch base, quarter panel, core of armrest, door trim, seat structure, console box, dashboard, various instrument panels, deck trim, bumper, A spoiler, cowling, etc. can be illustrated.

  Moreover, as a building and furniture use, the covering material etc. of various furniture, such as a door covering material, a door structure material, a desk, a chair, a shelf, and a rattan, can be illustrated.

  10: pretreatment, 20: micronization (fibrillation) treatment, 30x, 30y: drying treatment, 40x: (primary) kneading treatment, 40y: solid phase shearing treatment, 50: compatibilizer addition treatment, 60: (secondary ) Kneading, 70: molding, C: dispersion, P: pulp fiber, Rx: low melting point polypropylene, Ry: polypropylene other than low melting point polypropylene, Rz: compatibilizer, W: water.

Claims (7)

A thermoplastic resin composition comprising a thermoplastic resin and a plant fiber as a reinforcing material of the thermoplastic resin,
The vegetable fiber has an average fiber diameter of 20 to 500 nm, a water retention of 350% or less, a sedimentation rate of 0.030 mm / min or less, and a pulp viscosity of 3.5, which are obtained by refining pulp fibers containing lignin. More than 4.0 cps cellulose nanofibers,
Thermoplastic resin composition characterized in that. The thermoplastic resin and the cellulose nanofibers are
Blends of relatively low melting point thermoplastic resin and cellulose nanofibers as a substrate for dispersing cellulose nanofibers, and heat having a melting point higher than the relatively low melting point thermoplastic resin added to the blend Plastic resin,
The blending ratio of the thermoplastic resin having a melting point higher than that of the relatively low melting point thermoplastic resin is 100 to 10000 parts by mass with respect to 100 parts by mass of the relatively low melting point thermoplastic resin.
The thermoplastic resin composition according to claim 1. The thermoplastic resin and the cellulose nanofibers are
It is a kneaded product of dry mixed powder of cellulose nanofiber and thermoplastic resin,
The thermoplastic resin composition according to claim 1. Pulp fiber containing lignin is mechanical pulp,
And the blending ratio of the mechanical pulp to the total pulp fibers having an average fiber diameter of 20 to 500 nm is 50% by mass or more.
The thermoplastic resin composition according to any one of claims 1 to 3. The crystallinity of the cellulose nanofibers is 50 to 70%,
The thermoplastic resin composition according to any one of claims 1 to 4. The peak value in the pseudo particle size distribution curve of the cellulose nanofibers is one peak,
The thermoplastic resin composition according to any one of claims 1 to 5. The peak value is 5 to 25 μm,
The thermoplastic resin composition according to claim 6.

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