JP6460736B2 - Thermoplastic resin composition - Google Patents

Description

  The present invention relates to a thermoplastic resin composition.

  Conventionally, carbon fiber or glass fiber has been used as a reinforcing material for thermoplastic resin. However, carbon fibers are not suitable for thermal recycling because they are difficult to burn, and have a problem of high price. Glass fibers also have a disposal problem in thermal recycling.

  Therefore, in recent years, research has been conducted on a technique for using plant fibers, which are relatively inexpensive and have no thermal recycling problem, as a reinforcing material for thermoplastic resins. Explaining this point in detail, plant fibers are not used by artificially synthesizing them into fibers like carbon fibers or glass fibers, but they are used by loosening the microfibers of plants, so they are inexpensive. It becomes. As for the problem of thermal recycling, carbon fiber and glass fiber remain as ash during incineration, causing problems such as blockage of furnace piping and landfill treatment by ash, while plant fiber remains almost as ash. Therefore, problems such as blockage of furnace piping and landfill treatment do not occur.

  At present, proposals have been made to use cellulose nanofibers obtained by processing plant fibers as a reinforcing material for thermoplastic resins. The thermoplastic resin composition using the cellulose nanofibers as a reinforcing material is said to be as light as 1/5 of steel and have the same strength.

  In this regard, for example, Patent Documents 1 to 3 disclose a technique for surface-modifying cellulose microfibrils and reinforcing a thermoplastic resin. However, the surface modifier has a problem of being deactivated in water. In addition, since the reaction is very slow, it must be treated in an organic solvent, resulting in a problem of solvent treatment. That is, when an organic solvent is used, it is necessary to take measures to prevent the organic solvent from being scattered in the atmosphere in each step, to newly install a solvent processing facility, and the cost increases.

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

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

  The main problem to be solved by the invention is to provide a thermoplastic resin composition which is relatively inexpensive and does not cause problems of thermal recycling, solvent processing, etc. and has high strength.

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

(Function and effect)
When the plant fiber used as the raw material is pulp fiber, the resulting thermoplastic resin composition can be made inexpensive and the problem of thermal recycling can be avoided. Moreover, it is not necessary to use a surface modifier, and the problem of solvent treatment can be avoided.

  Since cellulose nanofibers are hydrophilic, they are inherently poor in bondability with hydrophobic thermoplastic resins and tend to have poor reinforcing effects, particularly mechanical strength such as bending strength. However, if the pulp fiber used as the raw material of the cellulose nanofiber is a pulp fiber containing lignin, the cellulose nanofiber also contains lignin. As a result, this lignin functions as a bonding agent between the cellulose nanofibers and the thermoplastic resin, and the bonding properties between them and the strength of the thermoplastic resin composition are improved.

  Cellulose nanofibers have poor dispersibility in thermoplastic resins. However, cellulose nanofibers containing lignin have a low water retention compared to cellulose nanofibers not containing lignin. Especially when the average fiber diameter is 500 nm or less, the drainage, dehydration, drying, and thermoplastic resin Dispersibility is improved. As a result, the strength of the thermoplastic resin composition is also improved. In this respect, when the dehydrating property of the cellulose nanofiber is improved, for example, the energy when the cellulose nanofiber is kneaded with the thermoplastic resin to be dehydrated can be reduced, which is advantageous in terms of production cost. However, if the refinement process is performed until the average fiber diameter is less than 20 nm, the cost for the refinement process increases, and therefore the average fiber diameter is preferably 20 nm or more.

  In addition, the present inventors refined LBKP and NBKP not containing lignin and BTMP containing lignin, and the obtained cellulose nanofibers were dispersed in water to form a slurry having a concentration of 2%. The test was performed by centrifuging for 10 minutes. As a result, the cellulose nanofiber obtained by refining LBKP and NBKP had a concentration of 7%, whereas the cellulose nanofiber obtained by refining BTMP had a concentration of 15%.

  In addition, as described above, when the average fiber diameter is 500 nm or less, the dehydrating property and the like are improved, but the mechanical strength such as the bending strength and the elastic modulus of the obtained thermoplastic resin composition is also improved. The inventors of the present invention used BTMP (average fiber diameter of 10 to 50 μm) and cellulose nanofibers (average fiber diameter of 500 nm or less) obtained by refining BTMP, a thermoplastic resin (PP and MAPP) powder, and later described. The test was carried out by direct biaxial kneading instead of the masterbatch method and solid phase shearing method. As a result, the bending strength and elastic modulus of the obtained thermoplastic resin composition were BTMP <cellulose nanofiber.

(Invention of Claim 2)
The thermoplastic resin and the cellulose nanofiber are:
A kneaded product of a thermoplastic resin having a relatively low melting point and a cellulose nanofiber serving as a substrate for dispersing the cellulose nanofibers, and a heat having a higher melting point than the thermoplastic resin having a relatively low melting point added to the kneaded product A plastic resin,
The mixing ratio of the relatively low melting point of the thermoplastic thermoplastic resin having a melting point higher than the resin is 100 to 10,000 parts by mass with respect to the relatively low melting 100 parts by weight of a thermoplastic resin,
The thermoplastic resin composition according to claim 1.
(Invention of Claim 3)
The thermoplastic resin and the cellulose nanofiber are:
Is a kneaded product of a dry powder mixture of the cellulose nanofiber及beauty thermoplastic resin,
The thermoplastic resin composition according to claim 1.
(Invention of Claim 4)
The pulp fiber containing lignin is mechanical pulp,
And the compounding ratio with respect to all the pulp fibers of the said mechanical pulp whose average fiber diameter is 20-500 nm is 50 mass% or more,
The thermoplastic resin composition according to any one of claims 1 to 3.

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

(Invention of Claim 5)
The crystallinity of the cellulose nanofiber is 50 to 70%.
The thermoplastic resin composition of any one of Claims 1-4.

(Function and effect)
When the degree of crystallinity of the cellulose nanofiber is less than 50%, there is no problem in compatibility with the thermoplastic resin, but the strength of the fiber itself is lowered, so the strength of the thermoplastic resin composition tends to be inferior.

  On the other hand, when the crystallinity of the cellulose nanofiber exceeds 70%, the proportion of strong hydrogen bonds in the molecule increases and the fiber itself becomes stiff, but the compatibility with the thermoplastic resin decreases, and the thermoplastic resin composition The strength of the object tends to be inferior.

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

(Function and effect)
That the peak value in the pseudo particle size distribution curve of cellulose nanofiber is one peak means that the uniformity of the fiber length and the fiber diameter is high, and drying and dispersion proceed uniformly. Moreover, when the uniformity of fiber diameter and 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 of Claim 7)
The peak value is 5 to 25 μm.
The thermoplastic resin composition according to claim 6.

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

  On the other hand, if the peak value exceeds 25 μm, the refinement process is insufficient and the uniformity of the fiber diameter and fiber length tends to be inferior.

  According to the present invention, a thermoplastic resin composition is obtained that is relatively inexpensive, does not cause problems such as thermal recycling and solvent treatment, and has 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 this embodiment contains a thermoplastic resin and cellulose nanofibers that are plant fibers, and further has a compatibilizing agent added thereto.

(Pulp fiber)
Cellulose nanofibers can be obtained by refining (defibrating) pulp fibers. As a fiber used as a raw material, one type or two or more types can be selected and used from plant-derived fibers, animal-derived fibers, microorganism-derived fibers, and the like. However, it is preferable to use at least pulp fibers which are vegetable fibers, and pulp fibers containing lignin such as waste paper pulp (DIP) such as magazine waste paper pulp (MDIP) and newspaper waste paper pulp (NDIP), mechanical pulp and the like ( It is more preferable to use fibers contained as 50% by mass or more), and it is particularly preferable to use mechanical pulp.

  Cellulose nanofibers obtained from pulp fibers not containing lignin are fine and have a large specific surface area, and have many hydroxyl groups on the surface. Therefore, the drainage and dewaterability are poor and it is difficult to use as a dispersion described later. Moreover, since the cellulose nanofiber obtained from the pulp fiber has hydrophilicity derived from cellulose, the compatibility with the thermoplastic resin which is hydrophobic is poor and the dispersibility is poor. In contrast, cellulose nanofibers obtained from pulp containing lignin, such as mechanical pulp, contain lignin that is more hydrophobic than cellulose, so this lignin functions as a binder for cellulose nanofibers and thermoplastic resins. Bondability, compatibility, and strength of the thermoplastic resin composition are improved.

  In this regard, the present inventors examined the water retention of fibers after refinement 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 water retention level of LBKP and NBKP significantly increases with the miniaturization, whereas the water retention level of BTMP does not increase significantly. Therefore, when chemical pulp is used, it is difficult to reduce the water retention of cellulose nanofibers to a desired value or less, and when mechanical pulp is used, it is easy to reduce the water retention of cellulose nanofibers to a desired value or less. It became clear.

  Examples of the mechanical pulp include stone grand pulp (SGP), pressurized stone grand pulp (PGW), refiner ground pulp (RGP), chemi-ground pulp (CGP), thermo grand pulp (TGP), ground pulp (GP), One or more types can be selected and used from thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), refiner mechanical pulp (RMP), and the like.

(Pretreatment process)
It is preferable that the pulp fiber has a shape suitable for the fine processing, for example, powder.

  Moreover, the pulp fiber can be subjected to chemical treatment such as phosphate esterification treatment, acetylation treatment, and cyanoethylation treatment, if necessary.

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

(Miniaturization process)
The pulp fiber is subjected to a pretreatment as necessary and then subjected to a finer (defibration) treatment. By this refinement treatment, the pulp fibers are microfibrillated to become cellulose nanofibers.

  The refinement process is performed by, for example, one or more of a high-pressure homogenizer, a homogenizer such as a high-pressure homogenizer, a stone mill type friction machine such as a grinder or an attritor, a refiner such as a conical refiner or a disc refiner, or various bacteria. This method can be used selectively.

  However, the refinement treatment is preferably performed using at least one of a grinder that grinds between rotating grindstones and a wet atomizer that refines with a high-pressure water stream. As the grinder, for example, a mass collider manufactured by Masuko Sangyo Co., Ltd. can be used. Moreover, as a wet atomization apparatus, for example, a starburst of Sugino Machine Co., Ltd., a jet mill of Joko Co., Ltd., etc. can be used.

  The above-mentioned refinement treatment is, for example, an average fiber diameter, water retention, crystallinity, peak value of pseudo particle size distribution, tentacle test results, sedimentation speed, pulp viscosity, etc. of the obtained cellulose nanofibers at desired values or It is preferable to perform the evaluation.

  Cellulose nanofibers are fibers made of cellulose or cellulose derivatives. Ordinary cellulose nanofibers have strong hydration properties, and stably maintain a dispersed state (dispersion state) by hydrating in an aqueous medium. The single fiber constituting the cellulose nanofiber may be formed into a fibrous shape by collecting a plurality of filaments in an aqueous medium. The average fiber diameter of normal cellulose nanofibers is 4 to 2000 nm. The 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, when 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 decreases. Therefore, there is a tendency that the reinforcing effect of the thermoplastic resin composition is inferior. In addition, the time for the miniaturization process becomes longer, leading to an increase in manufacturing cost. On the other hand, when the average fiber diameter exceeds 500 nm, the fineness is insufficient and the dispersibility of the fibers tends to be inferior. 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 the total 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 the single fiber whose diameter exceeds 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 all pulp fibers is preferably 50% by mass or more, more preferably 70% by mass or more, and particularly preferably 90% by mass or more. When the blending ratio is less than 50% by mass, the water retention of cellulose nanofibers obtained by refining is not sufficiently reduced, and the drainage, drying properties, compatibility with thermoplastic resins, etc. tend to be inferior. In addition, the upper limit of the mixing ratio of mechanical pulp is 100% by mass.

  The average fiber diameter can be arbitrarily adjusted in the pulp fiber, the pretreatment step, and the refinement treatment step.

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

  The average fiber length can be arbitrarily adjusted in the pulp fiber, the pretreatment process, and the refinement treatment process.

(Water retention)
The water retention of the cellulose nanofiber is preferably 350% or less, more preferably 300% or less, and particularly preferably 280% or less. When the water retention exceeds 350%, the drainage, drying property, and compatibility with the thermoplastic resin tend to be inferior. Moreover, in order to make the reinforcing effect of the thermoplastic resin composition excellent, it is necessary to sufficiently dry the cellulose nanofibers and perform uniform dispersion in the thermoplastic resin. However, since cellulose nanofibers have high cohesiveness, they tend to aggregate during a drying process or a kneading process with a thermoplastic resin. Therefore, the water retention of the cellulose nanofiber is set to 350% or less, and the drainage, the drying property, and the compatibility with the thermoplastic resin are excellent, so that the drying treatment and the kneading treatment with the thermoplastic resin are performed. Aggregation can be suppressed, and the reinforcing effect of the thermoplastic resin composition can be made sufficient.

  The degree of water retention can be arbitrarily adjusted in the pulp fiber, pretreatment process, and refinement treatment process.

(Crystallinity)
The crystallinity of the cellulose nanofiber 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%, the compatibility with the thermoplastic resin is improved, but the strength of the fiber itself is lowered, so that the reinforcing effect of the thermoplastic resin composition tends to be inferior.

  On the other hand, the crystallinity of the cellulose nanofiber 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 stiff, but the compatibility with the thermoplastic resin decreases and the reinforcing effect of the thermoplastic resin composition is poor. Tend. In addition, it tends to be difficult to chemically modify the cellulose nanofibers.

  The crystallinity can be arbitrarily adjusted in the pulp fiber, the pretreatment process, and the refinement treatment process.

(Peak value)
The peak value in the pseudo particle size distribution curve of the cellulose nanofiber is preferably one peak. In the case of one peak, the cellulose nanofiber has high fiber length and fiber diameter uniformity, and is excellent in drying properties. Moreover, when the fiber diameter and fiber length uniformity are 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 nanofiber 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 micronization treatment of the cellulose nanofiber 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. If the peak value exceeds 25 μm, miniaturization is insufficient and the fiber diameter and fiber length tend to be inferior.

(Settling speed)
The sedimentation rate of the cellulose nanofiber 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 due to hydrogen bonding in the fibers, and the reinforcing effect of the thermoplastic resin composition tends to be inferior. In addition, it is thought that an apparent particle diameter becomes large and the sedimentation rate increases, so that a fiber is long.

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

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

(Tentacle test)
The tentacle test described above, which is a factor in the progress of the micronization process, is that when 1 mL of 2% cellulose nanofiber aqueous dispersion is placed on the index finger, the dispersion is sandwiched between the thumb and index finger, and the thumb is circulated 20 times. This is a test for visually confirming whether or not the fibrous material remains between the finger and the index finger. The micronization treatment is preferably performed so that no fibrous material remains in this tentacle test. The inventors have conducted various tests and examinations, and as a result, according to this tentacle test, it is possible to quickly confirm the progress of the miniaturization process and recognize that the manufacturing efficiency can be improved. It came. If the fibrous material remains, the uniformity of fiber diameter and fiber length tends to be inferior.

(Fine fiber)
Cellulose nanofibers should contain one or more microfibrils called microfibril cellulose, microfibrillar microfibers, microfiber cellulose, microfibrillated cellulose, super microfibril cellulose, etc. In addition, these fine fibers may be included. Moreover, the fiber which refined | miniaturized these fine fibers further can also be included, and may be included.

(Dispersion)
Cellulose nanofibers obtained by micronization are dispersed in an aqueous medium to obtain a dispersion. The total amount of the aqueous medium is particularly preferably water, but an aqueous medium in which a part of the aqueous medium is another liquid having compatibility with water can also be preferably used. As other liquids, 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.

(B type viscosity)
The B-type viscosity of the dispersion when the concentration of cellulose nanofibers is 2% (w / w) 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, a large amount of energy is required to knead the cellulose nanofiber dispersion and the thermoplastic resin, that is, to disperse the cellulose nanofiber in the thermoplastic resin. This leads to an increase in manufacturing costs.

  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 resins and aromatic polyester resins, polyacrylic resins such as polystyrene, methacrylate, and acrylate, polyamide resins, One type or two or more types can be selected and used from polycarbonate resin, polyacetal resin and the like.

  However, it is preferable to use at least one of polyolefin and polyester resin. As the polyolefin, it is preferable to use polypropylene. Furthermore, examples of the polyester resin include aliphatic lactic acid resins such as polylactic acid and polycaprolactone. Examples of the aromatic polyester resin include polyethylene terephthalate and the like. It is preferable to use a polyester resin having the above (also simply referred to as “biodegradable resin”).

  As a biodegradable resin, it can select and use 1 type (s) or 2 or more types 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 kinds selected from polymers and copolymers of hydroxycarboxylic acids such as lactic acid, malic acid, glucose acid, and 3-hydroxybutyric acid are selected. Can be used. However, it is preferable to use lactic acid. As this lactic acid, for example, L-lactic acid, D-lactic acid or the like can be used, and these lactic acids may be used alone or in combination of two or more.

  As the caprolactone-based aliphatic polyester, for example, one kind or two or more kinds can be selected and used from polycaprolactone, a copolymer of polycaprolactone and the like and a copolymer of the above hydroxycarboxylic acid.

  As the dibasic polyester, for example, one or two or more kinds selected from polybutylene succinate, polyethylene succinate, polybutylene adipate and the like can be used.

  A biodegradable resin may be used individually by 1 type, or may use 2 or more types together.

  The thermoplastic resin may contain an inorganic filler. Examples of the inorganic filler include simple elements of metal elements in Group I to Group VIII of the periodic table such as Fe, Na, K, Cu, Mg, Ca, Zn, Ba, Al, Ti, and silicon elements. Examples thereof include oxides, hydroxides, carbon salts, sulfates, silicates, sulfites, and various clay minerals composed of these compounds.

  Specifically, for example, barium sulfate, calcium sulfate, magnesium sulfate, sodium sulfate, calcium sulfite, zinc oxide, silica, heavy calcium carbonate, light calcium carbonate, aluminum borate, alumina, iron oxide, calcium titanate, hydroxide Examples include aluminum, magnesium hydroxide, calcium hydroxide, sodium hydroxide, magnesium carbonate, calcium silicate, clay lastonite, glass beads, glass powder, silica sand, meteorite, quartz powder, diatomaceous earth, and white carbon. .

  A plurality of the above inorganic fillers may be contained. Moreover, it may be contained in waste paper pulp.

(Other raw materials)
In addition to the compatibilizer described later, the raw material of the thermoplastic resin composition includes, for example, one or more of antistatic agents, flame retardants, antibacterial agents, colorants, radical scavengers, foaming agents and the like. It can select and add in the range which does not inhibit the effect of this invention.

(Mixing ratio)
The blending ratio of the cellulose nanofiber and the thermoplastic resin is preferably 1 part by mass or more for the cellulose nanofiber and 99 parts by mass or less for the thermoplastic resin, 2 parts by mass or more for the cellulose nanofiber, and 98 parts by mass for the thermoplastic resin. More preferably, the amount of cellulose nanofibers is 3 parts by mass or more, and the thermoplastic resin is 97 parts by mass or less. The cellulose nanofiber is preferably 50 parts by mass or less, the thermoplastic resin is preferably 50 parts by mass or more, the cellulose nanofiber is 40 parts by mass or less, and the thermoplastic resin is more preferably 60 parts by mass or more. It is particularly preferable that the nanofiber is 70 parts by mass or less and the thermoplastic resin is 30 parts by mass or more. However, when the blending ratio of the cellulose nanofiber is 3 to 10 parts by mass, the strength of the thermoplastic resin composition, particularly the strength of bending strength and bending modulus can be remarkably improved.

  In addition, the content rate of the cellulose nanofiber and the thermoplastic resin contained in the finally obtained thermoplastic resin composition is usually the same as the above-described blending ratio of the cellulose nanofiber and the thermoplastic resin.

(Dehydration and drying process)
Cellulose nanofibers and thermoplastic resins are dehydrated and dried. However, it is preferable to perform a dehydration process and a drying process together. By processing both together, a large amount and efficient processing becomes possible. The dehydration process and the drying process can be performed in separate processes / apparatuses, but can also be performed in the same process / apparatus, and it is more efficient to perform them in the same process / apparatus.

  For dehydration / drying treatment, for example, one or more selected from freeze dryer, vacuum dryer, heat dryer, stationary dryer, spray dryer, kneader, twin screw kneader, etc. are used. can do.

  However, for the dehydration / drying treatment, it is preferable to use one or more selected from a freeze dryer, a kneader, and a twin-screw kneader, and it is preferable to use a freeze dryer or a heat dryer. Particularly preferred.

  When using a freeze dryer, 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 processing problems arise. In addition, when t-butanol is used, there are advantages that treatment in a short time is possible, energy efficiency is excellent, and aggregation of cellulose nanofibers can be more reliably prevented.

  Examples of the heat dryer include a Banbury mixer, a single screw or a multi-screw kneader having two or more screws, a kneader, a solid-phase shear extruder, a lab plast mill, a planetary stirrer, etc. It is preferable to use one or more selected from (heating stirrer).

  The dehydration / drying process is performed by melting a thermoplastic resin in the “masterbatch method” to be described later, and is performed without melting the thermoplastic resin in the “solid phase shearing method”. When the nanofibers are simply kneaded, they may be melted or not melted.

  However, in the masterbatch method and the solid-phase shearing method, the cellulose nanofiber dispersion is dehydrated and dried together with the thermoplastic resin before the dehydration and drying treatment with a continuous filtration apparatus equipped with a centrifuge or filter cloth or the like. It is preferable to concentrate to a solid content concentration of%. By pre-concentrating, the time for drying or dehydration and drying can be shortened.

(Kneading process)
The cellulose nanofibers and thermoplastic resin that have undergone the dehydration and drying treatment are kneaded.

  For this kneading treatment, for example, one or more types selected from a single-screw or bi-axial or more multi-screw kneader, a mixing roll, a kneader, a roll mill, a Banbury mixer, a screw press, a disperser, etc. are used. 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, but is preferably 80 to 220 ° C, more preferably 90 to 210 ° C, A temperature of 100 to 200 ° C. is particularly preferable.

  The kneading time 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 nanofiber and the thermoplastic resin.

  As the compatibilizing agent, it is preferable to use one having a structure in which the polymer main chain has an acid anhydride group in the side chain.

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

  The compatibilizer is preferably added so as to be 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, relative to 100 parts by mass of the thermoplastic resin. It is particularly preferable to add so as to be 0 parts by mass or more. Moreover, it is preferable to add so that it may become 10 mass parts or less, It is more preferable to add so that it may become 8 mass parts or less, It is especially preferable to add so that it may become 5 mass parts 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, a method of producing a thermoplastic resin composition by using a thermoplastic resin and cellulose nanofibers as raw materials and adding a compatibilizing agent, the strength of the resulting thermoplastic resin composition. Will be described below (hereinafter also referred to as “master batch method”).

  In this master batch method, first, pulp fibers (P) are pretreated (10) as necessary, and then refined (20) to obtain cellulose nanofibers. The cellulose nanofibers are mixed with water (W). Mix to make dispersion (C). Next, the dispersion (C) and a thermoplastic resin, preferably a low-melting point thermoplastic resin (Rx), are dehydrated and dried (30x) and subjected to a primary kneading process (40x). Then, a thermoplastic resin (Ry) and further a compatibilizer (Rz) are added to the primary kneaded product, and a secondary kneading process (50x) and a molding 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 in addition to 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 the nanofibers. Moreover, the primary kneaded material in which the low-melting point thermoplastic resin (Rx) and the nanofiber are combined plays a role as a so-called master batch for the purpose of coloring or reinforcement. And the target thermoplastic resin composition can be obtained by knead | mixing this masterbatch and thermoplastic resin (Ry) so that it may become a desired compounding ratio.

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

  This master batch method has one feature in that a thermoplastic resin such as a low melting point thermoplastic resin (Rx) is melted in the dehydration / drying process (30x) and the primary kneading process (40x).

  In the master batch method, the temperature of the dehydration / drying treatment (30x) is appropriately set according to the type of the 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 the thermoplastic resin, it is preferably 90 to 130 ° C., more preferably 90 to 120 ° C. 90 to 110 ° C. is particularly preferable.

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

  The temperature of the primary kneading treatment (40x) is also set as appropriate 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 the thermoplastic resin, it is preferably 90 to 130 ° C., more preferably 90 to 120 ° C. 90 to 110 ° C. is 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.

  Examples of the primary kneading apparatus (40x) include, for example, a kneader, a single-screw or multi-screw kneader, a mixing roll, a kneader, a roll mill, a Banbury mixer, a Henschel mixer, a screw press, a disperser, etc. 1 type or 2 types or more can be selected and used from the apparatus which can shorten drying time like a machine.

  The secondary kneading process (50x) after adding the compatibilizer (Rz) is appropriately set according to the type of the thermoplastic resin (Ry) added after the primary kneading process (40x). For example, when a thermoplastic resin that does not have a low melting point, for example, polypropylene (melting point 130 ° C.) is used as the thermoplastic resin (Ry), the temperature is preferably 130 to 220 ° C., more preferably 130 to 215 ° C. Preferably, it is 130-210 degreeC.

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

  Examples of the secondary kneading apparatus (50x) include, for example, a kneader, a single screw or a multi-screw kneader with two or more screws, a mixing roll, a kneader, a roll mill, a Banbury mixer, a Henschel mixer, a screw press, a disperser, etc. 1 type or 2 types or more can be selected and used from the apparatus which can shorten drying time like a kneading machine.

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

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

  Examples of the molding processing apparatus include one or more of injection molding machines, blow molding machines, hollow molding machines, blow molding machines, compression molding machines, extrusion molding machines, vacuum molding machines, and pressure molding machines. Can be selected and used.

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

  In this solid-phase shearing method, first, the pulp fiber (P) is pretreated (10) as necessary, and then refined (20) to obtain cellulose nanofibers. The cellulose nanofibers are washed with water (W). To make a dispersion (C). Next, the dispersion (C) and the thermoplastic resin (Ry) are dehydrated and dried (30y), and subjected to solid phase shearing (40y). Then, a compatibilizing agent (Rz) is added to the solid phase sheared material, and kneading treatment (50y) and molding treatment (60) are performed to obtain the thermoplastic resin composition (S).

  This solid-phase shearing method has one feature in that the thermoplastic resin is not melted during the dehydration / drying treatment (30y). In this solid-phase shearing method, cellulose nanofibers are embedded and dispersed in the thermoplastic resin while moisture is evaporated in the process of dehydration / drying treatment (30y) and solid-phase shearing treatment (40y). The Thereby, cellulose nanofibers are interspersed in the thermoplastic resin (Ry), and the dry mixed powder of cellulose nanofiber and thermoplastic resin is also characterized.

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

  The duration 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.

  Examples of the dehydration / drying treatment (30y) device include a simple stirring device, a kneader, a single screw or a multi-screw kneader with two or more screws, a mixing roll, a kneader, a roll mill, a Banbury mixer, a Henschel mixer, a screw press, and a disperser. Etc. (including a device such as a vacuum kneader that can shorten the drying time) can be used by selecting one or more.

  The larger the area where the cellulose nanofibers and the thermoplastic resin (Ry) are in contact, the better the efficiency of the solid phase shearing treatment (40y). Therefore, the shape of the thermoplastic resin (Ry) is a powder with an average particle diameter of 1-1000 μm. It is preferable to keep the shape.

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

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

  Examples of the solid phase shearing (40y) apparatus include a kneader, a single-screw or multi-screw kneader, a mixing roll, a kneader, a roll mill, a Banbury mixer, a Henschel mixer, a screw press, a disperser, etc. 1 type or 2 types or more can be selected and used from the apparatus which can shorten drying time like a kneading machine.

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

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

  Examples of the kneading apparatus (50y) include, for example, a kneader, a uniaxial or biaxial or more multi-axial kneader, a mixing roll, a kneader, a roll mill, a Banbury mixer, a Henschel mixer, a screw press, a disperser, etc. 1 type or 2 types or more can be selected and used.

  The temperature during 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 for the forming 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 of injection molding machine, blow molding machine, hollow molding machine, blow molding machine, compression molding machine, extrusion molding machine, vacuum molding machine, pressure molding machine, etc. Two or more types can be selected and used.

(Molding process)
The cellulose nanofiber and the thermoplastic resin (kneaded material) to which the compatibilizing agent is added are kneaded again if necessary and then formed into a desired shape.

  In this respect, cellulose nanofibers are dispersed in the kneaded product, but it is excellent in moldability.

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

  This molding process can be performed by a known molding method, for example, mold molding, injection molding, extrusion molding, hollow molding, foam molding, or the like. Further, the kneaded product can be spun into a fiber and mixed with the above-described plant material or the like to form a mat or board. The fiber mixing can be performed by, for example, a method in which air fibers are simultaneously deposited.

  This molding process can be performed following the kneading process, or the kneaded product is once cooled and chipped using a crusher or the like, and then the chip is put into a molding machine such as an extrusion molding machine or an injection molding machine. It can also be done.

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

(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 membrane filter made of Teflon (registered trademark), and the solvent is substituted once with 100 ml of ethanol and three times with 20 ml of t-butanol. Next, the sample is freeze-dried and coated with osmium. 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 constituent fibers. Specifically, two diagonal lines are drawn on the observation image, and three straight lines passing through the intersections of the diagonal lines are arbitrarily drawn. Further, the total width of 100 fibers intersecting with the three straight lines is visually measured. And let the median diameter of a measured value be an average fiber diameter.

(Average fiber length)
In the same manner as in the case of the average fiber diameter, the length of each fiber is visually measured. The median length of the measured value is the average fiber length.

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

(Crystallinity)
It is a value measured by an X-ray diffraction method in accordance with “General Rules for X-ray Diffraction Analysis” of JIS-K0131 (1996).
In addition, a cellulose nanofiber has an amorphous part and a crystalline part, and a crystallinity degree means the ratio of the crystalline part in the whole cellulose nanofiber.

(Peak value)
Measured according to ISO-13320 (2009). More specifically, the volume-based particle size distribution in an aqueous dispersion of cellulose nanofibers is examined using a particle size distribution measuring device (laser diffraction / scattering particle size distribution measuring instrument manufactured by Seishin Corporation). And the mode diameter of a cellulose nanofiber is measured from this distribution. This mode diameter is defined as a peak value.

(Settling speed)
It measures based on JISZ8822 about the aqueous dispersion liquid of the cellulose nanofiber of solid content concentration 0.1%.

(Pulp viscosity)
Measured according to JIS-P8215 (1998). In addition, it means that the polymerization degree of a cellulose is so high that a pulp viscosity is high.

(B type viscosity)
An aqueous dispersion of cellulose nanofibers having a solid content concentration of 2% is measured according to “Method for measuring viscosity of liquid” in JIS-Z8803 (2011). The B type viscosity is a resistance torque when the slurry is stirred, and the higher the viscosity, the more energy required for stirring.

(With and without lignin)
The phrase “containing lignin” means a case where lignin affects an action effect such as a compatibility improvement or a reinforcing effect increase. Specifically, it means that the kappa number is 2.0 or more. Therefore, not containing lignin means that the kappa number is less than 2.0. If the kappa number is 20 or more, the compatibility is improved and the reinforcing effect is increased.

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

(Copper value)
It is the value measured based on JIS P8211: 2011 (pulp-kappa number test method). In addition, it means that there is so much lignin content 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)
First, 23 L of a 2 mass% aqueous dispersion of bleached mechanical pulp for papermaking (BTMP) was beaten using a Niagara beater until the freeness was 100 ml or less. Next, using a grinder (mass collider of Masuko Sangyo Co., Ltd.), BTMP refinement treatment is performed in 3 passes, and a particle size distribution peak value of 5 to 25 μm and a water retention of 200 to 280%, 2 to 3 mass% cellulose. A nanofiber slurry was obtained. This slurry was processed with a centrifuge at 9000 rpm for 10 minutes to obtain a dispersion of 7 to 15% by mass cellulose nanofibers.

(Master Badge)
Low-melting-point polypropylene (El Modu S901, manufactured by Idemitsu Kosan Co., Ltd., melting point: about 80 ° C.) was charged into a kneader adjusted to 105 ° C. (Laboplast Mill manufactured by Toyo Seiki Co., Ltd.) and melted. Subsequently, the 7-15 mass% cellulose nanofiber dispersion was gradually added so that the dry mass ratio of the low melting point polypropylene and the cellulose nanofiber was 50:50, and the water was removed. After the introduction of the dispersion liquid was completed, it was dried and dispersed at 80 rpm for 20 minutes to obtain a 50% cellulose nanofiber blended master batch. This master batch was cut into a 2 mm diameter and 2 mm long cylindrical shape using a pelleter to obtain pellets that could be easily put into a biaxial kneader.

(Kneading process)
Dry mass ratio of polypropylene pellets (Novatech PP injection molding grade MA3 manufactured by Nippon Polypro Co., Ltd., melting point 158 ° C.), the above master batch pellets, and maleic acid-modified polypropylene pellets (Yumex 1010 manufactured by Sanyo Chemical Industries) as a compatibilizer Was put into a 500 ml beaker and mixed so that the ratio became 80: 20: 1. This pellet mixture was kneaded at 45 rpm with a biaxial kneader prepared at 180 ° C. to obtain 10% by mass of cellulose nanofiber-containing polypropylene. This polypropylene was cut into a cylindrical shape having a diameter of 2 mm and a length of 2 mm with a pelleter to obtain 10% by mass blended polypropylene pellets of cellulose nanofibers.

(Molding process)
A 10% by mass cellulose nanofiber blended polypropylene pellet at 180 ° C. with a dumbbell-shaped test piece (grip distance 20 mm, width 3.9 mm, thickness 1.97 mm) and a rectangular parallelepiped test piece (length 59 mm, width 9.6 mm) , And a thickness of 3.8 mm).

(Example 2)
(Dispersion)
A cellulose nanofiber dispersion was obtained in the same manner as in Example 1.

(Solid phase solid)
500 ml of a dispersion of polypropylene powder (Novatech PP injection molding grade MA3 made by Nippon Polypro, particle size of about 500 μm, melting point 158 ° C.) and the above 7-15 mass% cellulose nanofiber slurry so that the dry mass ratio is 90: 5. It put into the beaker and stirred at 70 degreeC and 300 rpm for 2 hours using the propeller type | formula heating stirrer. After drying to a moisture content of 5 to 10% by this stirring, solid-phase shearing is performed at 60 rpm for 1 hour with a kneader (Laboplast Mill manufactured by Toyo Seiki Co., Ltd.), and a dry mixed powder of cellulose nanofibers and polypropylene A (solid phase sheared product) was obtained.

(Kneading process)
The above solid-phase sheared product and maleic acid-modified polypropylene powder (Kayaburd made by Kayaku Akzo) as a compatibilizing agent were put into a 500 ml beaker and mixed so that the dry mass ratio was 95: 5. The mixed powder was kneaded at 45 rpm with a biaxial kneader prepared at 180 ° C. to obtain a polypropylene blended with 5% by mass of cellulose nanofibers. This polypropylene was cut into a cylindrical shape having a diameter of 2 mm and a length of 2 mm by a pelleter to obtain 5% by mass blended polypropylene pellets of cellulose nanofibers.

(Molding process)
Polypropylene pellets containing 5% by mass of cellulose nanofiber blended at 180 ° C. are dumbbell-shaped test pieces (distance between gripping tools 20 mm, width 3.9 mm, thickness 1.97 mm) and rectangular parallelepiped test pieces (length 59 mm, width 9.6 mm). , And a thickness of 3.8 mm).

(Example 3)
(Dispersion)
A cellulose nanofiber dispersion was obtained in the same manner as in Example 1.

(Mixed powder)
500 ml of a dispersion of polypropylene powder (Novatech PP injection molding grade MA3 made by Nippon Polypro, particle size of about 500 μm, melting point 158 ° C.) and the above 7-15 mass% cellulose nanofiber slurry so that the dry mass ratio is 90: 5. It put into the beaker and stirred at 70 degreeC and 300 rpm for 2 hours using the propeller type | formula heating stirrer. After drying to a moisture content of 5 to 10% by this stirring, it is dried for 24 hours in a constant temperature drier adjusted to 105 ° C., and is a dry mixed powder of cellulose nanofibers and polypropylene (this powder is not a solid-phase sheared product. )

(Kneading process)
The mixed powder was mixed with maleic acid-modified polypropylene powder (Kayaburd made by Kayaku Akzo) as a compatibilizing agent in a 500 ml beaker so that the dry mass ratio was 95: 5. The mixed powder was kneaded at 45 rpm with a biaxial kneader prepared at 180 ° C. to obtain a polypropylene blended with 5% by mass of cellulose nanofibers. This polypropylene was cut into a cylindrical shape having a diameter of 2 mm and a length of 2 mm by a pelleter to obtain 5% by mass blended polypropylene pellets of cellulose nanofibers.

(Molding process)
Polypropylene pellets containing 5% by mass of cellulose nanofiber blended at 180 ° C. are dumbbell-shaped test pieces (distance between gripping tools 20 mm, width 3.9 mm, thickness 1.97 mm) and rectangular parallelepiped test pieces (length 59 mm, width 9.6 mm). , And a thickness of 3.8 mm).

(Example 4)
In Example 1, it was the same as Example 1 except that it was changed to bleached mechanical pulp for papermaking (BTMP) and used old paper pulp for papermaking (MDIP).

(Example 5)
In Example 2, it was the same as Example 2 except that it was changed to bleached mechanical pulp for papermaking (BTMP) and used old paper pulp for papermaking (MDIP).

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

(Comparative Example 2)
In Example 1, it was the same as Example 1 except that it changed to bleached mechanical pulp for papermaking (BTMP) and used softwood bleached kraft pulp for papermaking (NBKP).

(Comparative Example 3)
In the drying process of Example 1, it replaced with the dispersion liquid of the cellulose nanofiber, and it carried out similarly to Example 1 except having used the commercially available cellulose nanofiber slurry (commercial item).

(Comparative Example 4)
In the drying treatment of Example 1, it was the same as Example 1 except that CNF (cellulose nanofiber slurry) manufactured by Main University was used instead of the cellulose nanofiber dispersion.

(Comparative Example 5)
The drying process of Example 1 was the same as Example 1 except that CNC (cellulose nanocrystal slurry) manufactured by Maine University was used instead of the cellulose nanofiber dispersion.

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

(Comparative Example 7)
In Example 2, it 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)
In the drying process of Example 2, it changed into the dispersion liquid of a cellulose nanofiber, and it carried out similarly to Example 2 except having used the commercially available cellulose nanofiber slurry (commercial item).

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

  Conditions and results are shown in Tables 1 and 2.

(Evaluation method)
About each said test piece, bending strength, bending elastic modulus, tensile strength, tensile elastic modulus, Izod impact strength (with a notch), linear thermal expansion coefficient, and dispersibility were evaluated. The evaluation method was as follows.

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

(Tensile strength, tensile modulus)
About each dumbbell-type test piece, it measured based on JISK7161: 2014 (the test method of a plastic-tensile property). In addition, it means that tensile strength and a tensile elasticity modulus are so strong that a numerical value is large (high).

(Izod impact strength (with notch))
Each rectangular parallelepiped test piece was measured in accordance with JIS K7110: 1999 (Plastic-Izod impact strength test method). The notch depth was 2 mm. In addition, it means that impact strength is so strong that a numerical value is large.

(Linear thermal expansion coefficient)
Each rectangular parallelepiped test piece was measured according to JIS K7197: 2012 (linear expansion coefficient test method by thermomechanical analysis of plastic). The measurement conditions were the compression load method, the heating rate: 5 ° C./min, the temperature range: 30 to 160 ° C., and the measuring instrument: a thermomechanical analyzer (Thermo plus EVO II) manufactured by Rigaku Corporation. In addition, it means that dimensional stability is so good that a numerical value is small.

  As described above, the thermoplastic resin composition of the present invention has a stronger strength (enhancement effect) than conventional thermoplastic resins. Therefore, it can be used not only for applications in which a thermoplastic resin has been used conventionally, but also in applications that have been used up until now due to insufficient strength.

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

  Among the above, examples of automobile applications include interior materials, instrument panels, exterior materials, and the like. Specifically, for example, door base material, package tray, pillar garnish, switch base, quarter panel, armrest core material, door trim, seat structure material, console box, dashboard, various instrument panels, deck trim, bumper, Examples include spoilers and cowlings.

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

  10 ... Pretreatment, 20 ... Finening (defibration) treatment, 30x, 30y ... Drying treatment, 40x ... (Primary) kneading treatment, 40y ... Solid phase shearing treatment, 50 ... Compatibilizer addition treatment, 60 ... (Secondary) ) Kneading treatment, 70 ... Molding treatment, 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 which is a reinforcing material of the thermoplastic resin,
The plant fiber has an average fiber diameter of 20 to 500 nm obtained by refining pulp fiber containing lignin, a water retention of 350% or less, a sedimentation rate of 0.030 mm / min or less, and a pulp viscosity of 3.5. The cellulose nanofiber is 4.0 cps or less,
The thermoplastic resin composition characterized by the above-mentioned. The thermoplastic resin and the cellulose nanofiber are:
A kneaded product of a thermoplastic resin having a relatively low melting point and a cellulose nanofiber serving as a substrate for dispersing the cellulose nanofibers, and a heat having a higher melting point than the thermoplastic resin having a relatively low melting point added to the kneaded product A plastic resin,
The mixing ratio of the relatively low melting point of the thermoplastic thermoplastic resin having a melting point higher than the resin is 100 to 10,000 parts by mass with respect to the relatively low melting 100 parts by weight of a thermoplastic resin,
The thermoplastic resin composition according to claim 1. The thermoplastic resin and the cellulose nanofiber are:
Is a kneaded product of a dry powder mixture of the cellulose nanofiber及beauty thermoplastic resin,
The thermoplastic resin composition according to claim 1. The pulp fiber containing lignin is mechanical pulp,
And the compounding ratio with respect to all the pulp fibers of the said mechanical pulp whose average fiber diameter is 20-500 nm is 50 mass% or more,
The thermoplastic resin composition according to any one of claims 1 to 3. The crystallinity of the cellulose nanofiber is 50 to 70%.
The thermoplastic resin composition of any one of Claims 1-4. The peak value in the pseudo particle size distribution curve of the cellulose nanofiber 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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