JP7153152B1 - Resin composition and method for producing resin composition - Google Patents

Abstract

[Problem] To provide a resin composition in which nanocellulose is excellent in dispersibility in a thermoplastic resin and in which the generation of nanocellulose aggregates is suppressed by a simpler method. A thermoplastic resin and easily dispersible nanocellulose (B) dispersed in the thermoplastic resin are contained, and the easily dispersible nanocellulose (B) is composed of nanocellulose and the nanocellulose. and a modified polyolefin having a carboxyl group, wherein the thermoplastic resin includes a thermoplastic resin (A) having a melting point of 110° C. or lower. [Selection figure] None

Description

The present invention relates to a resin composition and a method for producing a resin composition.

Nanocelluloses (also called cellulose microfibrils), such as cellulose nanofibers (CNF) and cellulose nanocrystals (CNC), have less thermal deformation than glass. In addition, nanocellulose, which has high strength and low thermal expansion, is a useful material as a sustainable resource material. Based on these advantages, various techniques have been proposed in which nanocellulose is used as a reinforcing material for thermoplastic resins and nanocellulose is contained in thermoplastic resins.

On the other hand, since nanocellulose is hydrophilic and highly polar due to its abundant hydroxyl groups, it has an aspect of poor compatibility with general-purpose thermoplastic resins that are hydrophobic and have low polarity. For this reason, in the development of materials using nanocellulose, the surface modification of nanocellulose or the introduction of functional groups to nanocellulose is performed by chemical treatment to improve the compatibility of nanocellulose with general-purpose thermoplastic resins, and to improve the compatibility of nanocellulose with general-purpose thermoplastic resins. Various attempts have been made to improve dispersibility in plastic resins.

For example, Patent Literature 1 proposes a technique for easily dispersing nanocellulose, which is a hydrophilic substance, in a highly hydrophobic general-purpose thermoplastic resin by a simple method. As the technology, in Patent Document 1, nanocellulose and polyolefin including nanocellulose are included, and the polyolefin has a carboxy group, a specific acid value and a melting point, and easily contains 5 to 30% by mass of nanocellulose. A dispersible cellulose composition is disclosed.

JP 2017-141323 A

According to the technique disclosed in Patent Document 1, a simple method is effective for obtaining a resin composition in which nanocellulose is dispersed in a good state in a thermoplastic resin having high hydrophobicity and low polarity. Dispersible nanocellulose can be provided. However, even when such easily dispersible nanocellulose is used, depending on the type of thermoplastic resin mixed with it and the manufacturing conditions of the resin composition obtained by mixing them, nano Aggregates of cellulose may occur, and there is room for improvement in dispersibility.

Accordingly, it is an object of the present invention to provide a resin composition in which nanocellulose is excellent in dispersibility in a thermoplastic resin and in which the generation of nanocellulose aggregates is suppressed by a simpler method.

The present invention contains a thermoplastic resin and easily dispersible nanocellulose (B) dispersed in the thermoplastic resin, and the easily dispersible nanocellulose (B) is composed of nanocellulose and the nanocellulose. and a modified polyolefin having a carboxyl group, wherein the thermoplastic resin includes a thermoplastic resin (A) having a melting point of 110° C. or lower.

In addition, the present invention provides an easily dispersible nanocellulose (B) containing nanocellulose, a modified polyolefin having a carboxy group enveloping the nanocellulose (B), and a water-containing cellulose resin treated product containing water, and a melting point of 110 ° C. or less. Heating a certain thermoplastic resin (A) at a temperature not higher than 20 ° C. above the boiling point of water and mixing the thermoplastic resin (A) in a molten state; and heating at a temperature not lower than the boiling point of water, removing water from a mixture of the treated hydrous cellulose resin and the thermoplastic resin (A).

ADVANTAGE OF THE INVENTION According to this invention, the resin composition which is excellent in the dispersibility of the nanocellulose in a thermoplastic resin, and the generation|occurrence|production of the aggregate of nanocellulose was suppressed by a simpler method can be provided.

Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments.

<Resin composition and method for producing resin composition>
A resin composition of one embodiment of the present invention contains a thermoplastic resin and easily dispersible nanocellulose (B) dispersed in the thermoplastic resin. The easily dispersible nanocellulose (B) contains nanocellulose and modified polyolefin having a carboxyl group, which envelops the nanocellulose. The thermoplastic resin includes thermoplastic resin (A) having a melting point of 110° C. or lower. Since the resin composition has a structure in which the easily dispersible nanocellulose (B) is dispersed in the thermoplastic resin, it can take a solid form at room temperature (5 to 35° C.).

The technical significance of the configuration of the resin composition is also related to the method for producing the resin composition according to one embodiment of the present invention. Moreover, it is preferable that the resin composition of one embodiment of the present invention is obtained by the method for producing a resin composition of one embodiment of the present invention. The method for producing the resin composition comprises the steps of: easily dispersible nanocellulose (B) containing nanocellulose and modified polyolefin having a carboxyl group enveloping the nanocellulose; and a treated hydrous cellulose resin containing water; including mixing with a thermoplastic resin (A) which is: At this time, the hydrous cellulose resin-treated product and the thermoplastic resin (A) are heated at a temperature not higher than 20° C. higher than the boiling point of water and mixed in a molten state of the thermoplastic resin (A). Next, the production method includes removing water from the mixture of the treated hydrous cellulose resin and the thermoplastic resin (A) by heating at a temperature equal to or higher than the boiling point of water.

In this technology, in order to enhance the dispersibility of nanocellulose in a thermoplastic resin, easily dispersible nanocellulose (B) containing nanocellulose and a modified polyolefin having a carboxyl group enveloping the nanocellulose is used. . By using a modified polyolefin having a carboxy group (in this specification, it may be simply referred to as "modified polyolefin"), as described later, easily dispersible nanocellulose (B) and a hydrous cellulose resin containing it A processed product can be obtained by a simple method.

In addition, in this production method, the easily dispersible nanocellulose (B) is used in a water-containing state when the nanocellulose (easily dispersible nanocellulose (B)) and the thermoplastic resin (A) are mixed. That is, a composition containing easily dispersible nanocellulose (B) and water (herein referred to as "processed product of hydrous cellulose resin") is used. If the easily dispersible nanocellulose (B) mixed with the thermoplastic resin (A) is used in a dry state, the easily dispersible nanocellulose (B) tends to aggregate due to drying. On the other hand, by using a hydrous cellulose resin-treated product, the easily dispersible nanocellulose (B) is more easily dispersed when mixed with the thermoplastic resin (A) than when the easily dispersible nanocellulose (B) is used in a dry state. It is possible to suppress the generation of aggregates.

Furthermore, in this production method, in order to satisfactorily disperse the easily dispersible nanocellulose (B) in the thermoplastic resin, the treated product of the hydrous cellulose resin and the thermoplastic resin (A) are mixed with the thermoplastic resin (A). Mix in the melt. At this time, if the water contained in the hydrous cellulose resin-treated material is completely volatilized while the easily dispersible nanocellulose (B) and the thermoplastic resin (A) are not sufficiently mixed, the thermoplastic Aggregates of the easily dispersible nanocellulose (B) tend to form in the resin (A). Therefore, in the present production method, in mixing the hydrous cellulose resin-treated material and the thermoplastic resin (A), the mixture is heated at a temperature not higher than the boiling point of water +20°C so as to delay the evaporation of the water in the hydrous cellulose resin-treated material. Then, the thermoplastic resin (A) is mixed in a molten state. Then, in the present technology, a thermoplastic resin (A) with a melting point of 110° C. or less is used so that the thermoplastic resin (A) is in a molten state at a temperature of water's boiling point +20° C. or less.

According to the resin composition having the structure described above and the method for producing the resin composition, the dispersibility of nanocellulose in the thermoplastic resin is excellent and the generation of nanocellulose aggregates is suppressed by a simpler method. It becomes possible to provide a resin composition.

[Thermoplastic resin (A)]
The thermoplastic resin (A) is a thermoplastic resin having a melting point of 110° C. or lower. The melting point of the thermoplastic resin (A) is 100° C. or less because the dispersibility of the nanocellulose (easily dispersible nanocellulose (B)) in the resin composition is excellent and the generation of aggregates is easily suppressed. is preferably 95° C. or lower, and even more preferably 90° C. or lower. The lower limit of the melting point of the thermoplastic resin (A) is preferably 50° C. or higher, more preferably 55° C. or higher, and 60° C. or higher, from the viewpoint of the mechanical strength of the resin composition. More preferred. The melting point of the thermoplastic resin (A) can be measured by differential scanning calorimetry (DSC).

Examples of the thermoplastic resin (A) include polyethylene resins, polypropylene resins, ethylene/propylene copolymers, ethylene/α-olefin copolymers, propylene/α-olefin copolymers, ethylene/vinyl acetate copolymers, Polyolefin resins such as ethylene/vinyl alcohol copolymers and ethylene/ethyl acrylate copolymers; polyester resins such as polylactic acid; and polyether resins such as polyethylene glycol; Among them, because it has good compatibility with the modified polyolefin contained in the easily dispersible nanocellulose (B) described later, it becomes easy to mix with the easily dispersible nanocellulose (B), so the thermoplastic resin (A) Polyolefin-based resins are preferred as such.

Examples of polyolefin-based resins include homopolymers of olefin-based monomers and copolymers of monomer components containing olefin-based monomers as main components. That the monomer component forming the copolymer contains an olefinic monomer as a main component means that the total content of monomers corresponding to olefinic monomers in the monomer component is olefin It means that it is higher than the content of any monomer other than the system monomer. The content of the olefinic monomer in the monomer component forming the copolymer is preferably 50 to 100% by mass, more preferably 60 to 100% by mass, still more preferably 80 to 100% by mass. The copolymer includes a copolymer of two or more olefinic monomers, and a copolymer of an olefinic monomer and another monomer that can be copolymerized with the olefinic monomer, A copolymer of two or more olefinic monomers is preferred.

Examples of olefinic monomers include olefins such as ethylene and propylene; -olefins (eg, α-olefins having 2 to 12 carbon atoms); and cyclic olefins such as cyclopentene and norbornene; As described above, one kind of olefinic monomers may be used alone in the polyolefinic resin, or two or more kinds thereof may be used in combination.

Specific examples of more preferred polyolefin resins include high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polypropylene (PP), polybutene, hydrogenated polybutene, polyisobutylene, Polyolefin resins such as hydrogenated polyisobutylene, ethylene/propylene copolymers, ethylene/α-olefin copolymers, and propylene/α-olefin copolymers can be mentioned.

Among the polyolefin resins described above, the thermoplastic resin (A) more preferably contains a metallocene polyolefin resin because it easily satisfies the requirement that the melting point be 110° C. or less. A metallocene-based polyolefin resin is a polyolefin resin polymerized using a metallocene catalyst. Among them, at least one selected from the group consisting of metallocene-based polyethylene, metallocene-based polypropylene, metallocene-based ethylene/α-olefin copolymer, and metallocene-based propylene/α-olefin copolymer is more preferable.

From the viewpoint of mechanical strength of the resin composition, the weight average molecular weight (Mw) of the thermoplastic resin (A) is preferably 40,000 to 300,000, more preferably 50,000 to 200,000. It is more preferably 70,000 to 150,000. The Mw of the thermoplastic resin (A) can be a standard polystyrene-equivalent value measured by gel permeation chromatography (GPC).

Moreover, from the viewpoint of the mechanical strength of the resin composition, the melt flow rate (MFR) of the thermoplastic resin (A) is preferably 500 g/10 min or less. MFR is a value measured with a standard die (length 8.000 mm, hole diameter 2.095 mm) under conditions of a temperature of 190° C. and a load of 2.16 kg, in accordance with the provisions of ASTM D1238. The MFR of the thermoplastic resin (A) is more preferably 100 g/10 min or less, even more preferably 50 g/10 min or less. On the other hand, from the viewpoint of ease of melt-kneading when producing the resin composition and moldability of the resin composition, the MFR of the thermoplastic resin (A) is preferably 0.1 g/10 min or more, and 1 g/ It is more preferably 10 min or more, and even more preferably 5 g/10 min or more.

[Easily dispersible nanocellulose (B)]
The resin composition contains easily dispersible nanocellulose (B). The easily dispersible nanocellulose (B) contains nanocellulose and modified polyolefin having a carboxyl group, which envelops the nanocellulose. Since the easily dispersible nanocellulose (B) has a structure in which the nanocellulose is wrapped in a modified polyolefin having a carboxy group, it is more easily dispersed in water than the nanocellulose alone. Therefore, when producing a resin composition, a treated hydrous cellulose resin containing easily dispersible nanocellulose (B) having excellent dispersibility in water can be used.

The content of nanocellulose in the easily dispersible nanocellulose (B) in the resin composition is preferably 30% by mass or less based on the total mass of the resin composition (solid content). Nanocellulose (easily dispersible nanocellulose (B)) has excellent dispersibility in the resin composition and is more likely to suppress the generation of aggregates, so the content of nanocellulose should be 25% by mass or less. is more preferable, and 20% by mass or less is even more preferable. On the other hand, the content of nanocellulose in the resin composition is preferably, for example, 1% by mass or more. From the viewpoint of obtaining a more useful resin composition by increasing the nanocellulose content, the content of nanocellulose in the resin composition is more preferably 5% by mass or more, and more preferably 10% by mass or more. is more preferred.

The ratio of nanocellulose and modified polyolefin in the easily dispersible nanocellulose (B) is not particularly limited as long as the modified polyolefin envelops the nanocellulose. From the viewpoint of easily taking such a form, the content of nanocellulose in the easily dispersible nanocellulose (B) is 5 to 80% by mass based on the mass of the easily dispersible nanocellulose (B). It is preferably from 25 to 70% by mass, and even more preferably from 40 to 60% by mass. In addition, the content of the modified polyolefin in the easily dispersible nanocellulose (B) is preferably 20 to 95% by mass, preferably 30 to 75% by mass, based on the mass of the easily dispersible nanocellulose (B). more preferably 40 to 60% by mass. When the water-containing cellulose resin-treated material used for producing the resin composition consists of only the easily dispersible nanocellulose (B) and water, the amount (solid content) after removing the water is the easily dispersible nanocellulose (B). is mass. In this specification, each content of nanocellulose and modified polyolefin can take a value calculated based on each usage amount of nanocellulose and modified polyolefin.

In the resin composition, the easily dispersible nanocellulose (B) may form an ester bond through reaction between the carboxyl group of the modified polyolefin and the hydroxyl group of the nanocellulose. As a result, it can be expected that the dispersibility of the easily dispersible nanocellulose (B) in the thermoplastic resin will be further enhanced by bonding the modified polyolefin and the nanocellulose wrapped therein. Furthermore, if a thermoplastic resin (A) having excellent compatibility with modified polyolefin is selected, it is expected that the dispersibility of the easily dispersible nanocellulose (B) will be further enhanced.

The above ester bonds are formed when all of the carboxy groups of the modified polyolefin react with the hydroxyl groups of the nanocellulose, or when some of the carboxy groups of the modified polyolefin react with the hydroxyl groups of the nanocellulose. case is included. The above-mentioned ester bond can be formed by dehydration condensation, which can be caused by heat when mixing the easily dispersible nanocellulose (B) and the thermoplastic resin (A) or when removing water from the mixture. it is conceivable that.

(Nanocellulose)
Nanocellulose in easily dispersible nanocellulose (B) is cellulose with a width (fiber width or crystal width) of nanosize (1 to 1000 nm). Examples of nanocellulose include cellulose nanofibers (CNF) obtained from wood and the like, and cellulose nanocrystals (CNC), also called cellulose nanowhiskers (CNW); bacterial nanofibers produced by bacteria; and electrospinning. electrospun nanofibers produced from dissolved cellulose by a method; These 1 types can be used individually or in combination of 2 or more types. Among them, at least one of CNF and CNC is preferred. More preferably, the nanocellulose contains cellulose nanofibers.

Plant fibers, including cellulose, used as raw materials for CNF and CNC, for example, are obtained from natural plant sources such as wood, bamboo, hemp, jute, kenaf, cotton, beet, agricultural waste, and cloth, pulp, and Examples include regenerated cellulose fibers such as rayon and cellophane. Examples of wood include Sitka spruce, cedar, cypress, eucalyptus and acacia. Examples of paper include deinked waste paper, corrugated waste paper, magazines, copy paper, and the like. However, it is not limited to these. One type of vegetable fiber may be used alone, or two or more types may be used in combination.

Lignocellulose, which is the main component of plant fibers, is mainly composed of cellulose, hemicellulose, and lignin, and has a structure in which each is bound together. By mechanically and/or chemically treating this lignocellulose-containing plant fiber to remove hemicellulose and lignin and increase the purity of cellulose, pulp can be obtained. A bleaching treatment is also performed if necessary, and the amount of delignification can be adjusted to adjust the amount of lignin in the pulp.

Nanocellulose is preferably obtained by defibrating pulp. As the pulp, from the aspect of manufacturing methods such as mechanical treatment and chemical treatment, for example, ground wood pulp (GP), refiner ground pulp (RGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), etc. mechanical pulp (MP); chemical pulp such as kraft pulp (KP), sulfide pulp (SP), and alkaline pulp (AP); and semi-chemical pulp (SCP), chemigrand pulp (CGP), and chemi-mechanical pulp (CMP). ) etc. can be mentioned. In terms of raw materials, pulp includes wood pulp such as softwood pulp (NP) and hardwood pulp (LP); rice pulp, kenaf pulp, linen pulp, mulberry pulp, bagasse pulp, straw pulp, cotton pulp, bamboo pulp, and fruit pulp. Non-wood pulp such as pulp; waste paper pulp such as deinked waste paper pulp, corrugated waste paper pulp, and waste magazine pulp; In addition, bleached pulp (bleached pulp), unbleached pulp (unbleached pulp), and the like can be mentioned in terms of the presence or absence of bleaching treatment. One type of pulp may be used alone, or two or more types may be used in combination. Among pulps, bleached pulp (bleached pulp) is preferred. Among them, those having a kappa number of 5 or less, as measured according to JIS P8211:2011, are more preferable, and those having a kappa number of 2 or less are even more preferable.

Examples of methods for disentangling pulp include chemical disentanglement treatment, mechanical disentanglement treatment, and disentanglement treatment combining them. The chemical defibration treatment includes a method of chemically treating a suspension (slurry) containing pulp and water. Examples of the chemical treatment include an oxidation method using a TEMPO catalyst, a phosphorylation method, and a hydrolysis method using an enzyme. In these chemical treatments, a mechanical defibration treatment described below may be performed in addition to the chemical treatments, if necessary.

Mechanical fibrillation treatment includes, for example, a method of refining a suspension (slurry) containing pulp and water with a high-pressure water stream; a method of high-speed stirring with a wet stirrer; a method of grinding with a grinder; A method of beating with a beating machine; and a method of combining them; Examples of the method of pulverizing with a high-pressure water stream include a high-pressure jet mill (for example, a counter jet mill) using an underwater counter-impingement method. Examples of wet stirring devices include a high-pressure homogenizer and a bead mill. Examples of grinders include grinders and stone grinders. Examples of the beater include disc refiners and conical refiners. Among the nanocellulose obtained by the above-described defibration treatment, mechanically defibrated nanocellulose is preferable, and mechanically defibrated cellulose nanofiber is more preferable.

CNF suitable as nanocellulose can be obtained by defibrating plant fibers containing cellulose until the fiber width reaches the nanosize (1 to 1000 nm) level. For vegetable fibers, preferably pulp, more preferably a suspension containing pulp and water is used. In general, cellulose microfibrils (single cellulose nanofibers) with a width of about 4 nm exist as the smallest unit in plant cell walls. CNF is nano-sized cellulose formed by aggregation of cellulose microfibrils or multiple cellulose microfibrils. The arithmetic average fiber width of CNF is preferably 4 to 200 nm, more preferably 4 to 150 nm, and even more preferably 4 to 100 nm. The arithmetic mean value of the CNF fiber length is preferably about several μm, more preferably 5 μm or more. The specific surface area of CNF is preferably 70 to 300 m ² /g, more preferably 70 to 250 m ² /g, even more preferably 100 to 200 m ² /g.

CNC suitable as nanocellulose can be obtained by hydrolyzing plant fibers containing cellulose with an acid. For vegetable fibers, preferably pulp, more preferably a suspension containing pulp and water is used. In addition to the hydrolysis treatment with an acid, the defibration treatment may be performed as necessary. Examples of acids include sulfuric acid, hydrochloric acid, and hydrobromic acid. The CNC obtained by hydrolysis treatment with an acid is needle-shaped crystals, and the crystal width is preferably 4 to 100 nm, more preferably 10 to 50 nm, and even more preferably 10 to 30 nm in terms of arithmetic mean value. The arithmetic average crystal length of CNC is preferably 25 to 3000 nm, more preferably 100 to 500 nm, even more preferably 100 to 200 nm. The specific surface area of CNC is preferably 90 to 900 m ² /g, more preferably 100 to 500 m ² /g, even more preferably 100 to 300 m ² /g.

The arithmetic average value of the width (fiber width and crystal width) and length (fiber length and crystal length) of the nanocellulose described above is the average value when measuring at least 50 or more nanocelluloses in the field of view of the electron microscope. can take

(modified polyolefin)
The modified polyolefin having a carboxy group in the easily dispersible nanocellulose (B) is also called polyalkene. This modified polyolefin having a carboxy group is a polymer having a structure in which a carboxy group is introduced into the skeleton of a polyolefin synthesized using an olefin (alkene) as a monomer.

Examples of olefin monomers include ethylene, propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 3-methyl-1-pentene, 4-methyl-1-pentene and 1-heptene. , 4-methyl-1-hexene, 5-methyl-1-hexene, 1-octene, and 5-methyl-1-heptene. As the skeleton of the polyolefin, a skeleton such as a homopolymer of one of the above olefin monomers and a copolymer of two or more kinds of olefin monomers (graft copolymer, block copolymer, random copolymer), etc. can be mentioned.

The carboxy group in the modified polyolefin is obtained, for example, by a method of copolymerizing an unsaturated carboxylic acid-based monomer or the like that can be copolymerized with the above-mentioned olefin monomer with an olefin monomer, or a method of polymerizing an esterified product thereof and then hydrolyzing it. , can be introduced. Moreover, a carboxyl group can be introduced into the side chain of the polyolefin by grafting an unsaturated carboxylic acid-based monomer or the like using a peroxide or the like to the polyolefin obtained in advance. Examples of the unsaturated carboxylic acid-based monomer include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid; unsaturated carboxylic anhydrides such as maleic anhydride and itaconic anhydride; and styrene carboxylic acids such as 4-vinylbenzoic acid; and the like.

In order to obtain the easily dispersible nanocellulose (B) and the hydrous cellulose resin-treated material containing it, the modified polyolefin needs to have a carboxy group. This allows the modified polyolefin to be dispersed in an aqueous medium. Therefore, by using a modified polyolefin having a carboxy group in the form of an aqueous emulsion, that is, by using an emulsion in which the modified polyolefin is dispersed in an aqueous medium, easily dispersible nanocellulose (B) and containing it A treated product of hydrous cellulose resin can be obtained by a simple method.

The modified polyolefin preferably has an acid value of 1 to 60 mgKOH/g from the viewpoint of easy production of the easily dispersible nanocellulose (B) and a treated product of a hydrous cellulose resin containing the same. The acid value of the modified polyolefin is more preferably 10 mgKOH/g or more, more preferably 20 mgKOH/g or more. On the other hand, the acid value of the modified polyolefin is more preferably 50 mgKOH/g or less, even more preferably 40 mgKOH/g or less.

As used herein, the acid value of the modified polyolefin is represented by mg of potassium hydroxide required to neutralize 1 g of the modified polyolefin, and can be measured as follows. That is, the modified polyolefin to be measured is dissolved in a polyolefin-soluble solvent (e.g., xylene, octane, etc.) and titrated with a 0.1 mol/L potassium hydroxide/ethanol solution using a phenolphthalein solution as an indicator. Desired.

The melting point of the modified polyolefin is preferably 160°C or less. As a result, in the production of the resin composition, when the hydrous cellulose resin-treated product and the thermoplastic resin (A) are mixed in the molten state of the thermoplastic resin (A), the easily dispersible nanocellulose (B) and the The thermoplastic resin (A) becomes easy to mix. At this time, if the modified polyolefin in the easily dispersible nanocellulose (B) is also in a molten state, the easily dispersible nanocellulose (B) and the thermoplastic resin (A) are more easily mixed, and the easily dispersible nanocellulose (B ) dispersibility is further improved, making it easier to suppress the generation of aggregates. From this point of view, the melting point of the modified polyolefin is more preferably 100° C. or lower, more preferably 90° C. or lower, even more preferably 85° C. or lower, and particularly preferably 80° C. or lower. . The lower limit of the melting point of the modified polyolefin is preferably 50°C or higher, more preferably 55°C or higher, and even more preferably 60°C or higher. The melting point of the modified polyolefin can be measured by differential scanning calorimetry (DSC).

Regarding the relationship between the modified polyolefin and the thermoplastic resin (A) described above, the absolute value of the difference between the melting point of the thermoplastic resin (A) and the modified polyolefin is preferably 80° C. or less. From the viewpoint of improving the compatibility between the thermoplastic resin (A) and the modified polyolefin and easily increasing the dispersibility of the easily dispersible nanocellulose (B), there is a difference between the melting point of the thermoplastic resin (A) and the modified polyolefin. is more preferably 30° C. or less. Furthermore, the absolute value of the melting point difference is more preferably 20° C. or less, and even more preferably 10° C. or less.

(Manufacturing method of easily dispersible nanocellulose (B) and hydrous cellulose resin treated product)
The easily dispersible nanocellulose (B) is not particularly limited in its production method as long as nanocellulose wrapped in modified polyolefin having a carboxy group is obtained. A product obtained as a cellulose resin-treated product is preferred. In the method for producing a resin composition according to one embodiment of the present invention, a treated product of hydrous cellulose resin is used in order to obtain the desired resin composition. may contain.

A treated product of hydrous cellulose resin can be produced as follows. That is, an acid is added to a mixed dispersion of a nanocellulose aqueous dispersion and a modified polyolefin aqueous emulsion neutralized with an alkali to precipitate the modified polyolefin. As a result, the modified polyolefin precipitated in the mixed dispersion envelops the nanocellulose, making it possible to produce easily dispersible nanocellulose (B) and a hydrous cellulose resin-treated material containing the same.

The amount of each of the aqueous dispersion of nanocellulose and the aqueous emulsion of modified polyolefin used is such that the ratio (each content) of nanocellulose and modified polyolefin in the easily dispersible nanocellulose (B) obtained is within the range described above. amount is preferred.

The aqueous emulsion of modified polyolefin neutralized with an alkali is a dispersion in which modified polyolefin is emulsified and finely dispersed in an aqueous medium because the carboxyl groups are neutralized and ionized. By mixing this aqueous emulsion with an aqueous dispersion of nanocellulose, a mixed dispersion can be easily obtained, and easily dispersible nanocellulose (B) can be easily obtained. When obtaining the mixed dispersion, an aqueous emulsion of modified polyolefin is added to the aqueous nanocellulose dispersion and stirred so that the modified polyolefin can be precipitated more uniformly by adding an acid to the mixed dispersion. Homogenization is preferred. At this time, a stirrer such as a stirrer, a stirrer with a motor, a high-speed dissolver, a homomixer, a bead mill, or a high-pressure homogenizer can be used. If necessary, a water-soluble organic solvent, which may be contained as an aqueous medium in the modified polyolefin aqueous emulsion, may be added during homogenization.

From the standpoint of facilitating uniform deposition of the modified polyolefin by adding an acid to the mixed dispersion, the average particle size measured for the aqueous emulsion of the modified polyolefin neutralized with an alkali is preferably 300 nm or less. It is more preferably 250 nm or less. In the present specification, the average particle size of the aqueous emulsion of modified polyolefin neutralized with alkali is the particle size (median size) of the cumulative 50% of the volume-based particle size distribution measured by the dynamic light scattering method. take a value.

When an acid is added to a mixed dispersion of a nanocellulose aqueous dispersion and an alkali-neutralized modified polyolefin aqueous emulsion, the acid is preferably added while stirring the mixed dispersion. The stirrer mentioned above can also be used for stirring at this time. By adding an acid to the mixed dispersion, the ionized carboxy groups in the modified polyolefin are deionized, the water solubility of the modified polyolefin is reduced, and the modified polyolefin can be precipitated. As a result, the nanocellulose dispersed in the mixed dispersion is wrapped in the precipitated modified polyolefin in the dispersed state, and easily dispersible nanocellulose (B) can be obtained.

The above acids can include inorganic acids such as hydrochloric, hydrobromic, nitric, sulfuric, and phosphoric acids; and organic acids such as acetic and lactic acid; They may be used alone, or two or more of them may be used in combination. The acid is preferably diluted with water and used in the form of an aqueous solution so that the modified polyolefin can be precipitated uniformly in the mixed dispersion. The acid concentration of the aqueous solution is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass. The acid may be added all at once, added dropwise, or sprayed. Further, after adding the acid, it is preferable to add the acid so that the mixed dispersion becomes acidic. In that case, the pH of the mixed dispersion is more preferably 4 or less, more preferably 3 or less. .

After precipitating the modified polyolefin by adding an acid to the mixed dispersion, it is preferable to filter and wash. Prior to filtration, it is more preferable to heat the mixed dispersion after precipitation to aggregate the precipitate (modified polyolefin) around the nanocellulose in order to speed up the filterability. As a result, the mixed dispersion is concentrated, and it is possible to obtain a paste-like hydrous cellulose resin treated product (a hydrous paste) that is easy to handle when mixed with the thermoplastic resin (A) in the subsequent step. The solid content concentration of the hydrous cellulose resin-treated product is preferably 5 to 70% by mass, more preferably 10 to 60% by mass, even more preferably 20 to 50% by mass. In addition, the cellulose concentration in the hydrous cellulose resin-treated material is preferably 2 to 40% by mass, more preferably 5 to 30% by mass, even more preferably 10 to 25% by mass.

(Aqueous emulsion of modified polyolefin)
The aqueous emulsion of modified polyolefin used in producing the treated product of hydrous cellulose resin may be a commercially available product or may be produced as described below. Methods for producing an aqueous emulsion of modified polyolefin include, for example, a method in which polyolefin having a carboxy group is melted, neutralized with an alkali, and water is gradually added; a polyolefin having a carboxy group is dissolved in an organic solvent. and then mixing it with alkaline water to form an aqueous solution, and the organic solvent is left as it is or distilled off to form an emulsion;

As the organic solvent, water-soluble organic solvents such as alcohols, glycols, amines, and amides are preferable. Examples of alcohols include methanol, ethanol, propanol, and butanol. Examples of glycols include ethylene glycol, propylene glycol, diethylene glycol, ethylene glycol methyl ether, propylene glycol methyl ether, propylene glycol propyl ether, diethylene glycol methyl ether, diethylene glycol butyl ether, and diethylene glycol dimethyl ether. Examples of amines include methylamine, ethylamine, propylamine, butylamine, dimethylamine, diethylamine, trimethylamine, triethylamine, ethylenediamine, and diethylenetriamine. Examples of amides include dimethylformamide, dimethylacetamide, pyrrolidone, methylpyrrolidone, and ethylpyrrolidone.

The alkali used for neutralizing the carboxy groups in the modified polyolefin is not particularly limited. Examples of alkalis include ammonia; organic amines such as triethylamine, diethanolamine, dimethylaminoethanol, and aminomethylpropanol; alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; can be done. One type of alkali may be used alone, or two or more types may be used in combination.

(Nanocellulose aqueous dispersion)
The nanocellulose aqueous dispersion used in producing the treated product of hydrous cellulose resin may be a commercially available product or may be produced as described below. When the method for producing a resin composition according to an embodiment of the present invention includes producing the above-mentioned hydrous cellulose resin-treated product, when using the nanocellulose aqueous dispersion, the nanocellulose aqueous dispersion is produced. may include In that case, the production method preferably includes producing an aqueous suspension of nanocellulose as the aqueous dispersion of nanocellulose.

The aqueous suspension of nanocellulose can be produced by defibrating a suspension containing pulp and water (hereinafter sometimes referred to as "pulp suspension"). . As the method of defibration treatment, as described above, various chemical fibrillation treatments, mechanical fibrillation treatments, or a combination thereof can be adopted. Among them, the mechanical fibrillation treatment is preferable from the viewpoint of productivity because it is a treatment that does not use a chemical reaction, so that the number of manufacturing steps can be reduced. Above all, it is more preferable to produce an aqueous suspension of nanocellulose by grinding a suspension containing pulp and water with a grinder to defibrate the pulp. According to the mechanical defibration treatment using a grinder, a pulp suspension with a relatively high pulp concentration can be used compared to other defibration treatments, and as a result, the concentration of nanocellulose is increased. It becomes easier to obtain a high water suspension. It is more preferable to use a stone mill type grinder as the grinder from this point of view and because the number of manufacturing steps is small, so that the manufacturing cost can be suppressed.

The pulp concentration in the pulp suspension to be subjected to mechanical defibration treatment with a grinder and the nanocellulose concentration in the resulting aqueous suspension are preferably 0.1 to 10% by mass, and 0 It is more preferably 5 to 5% by mass, and even more preferably 1 to 2% by mass. The above pulp density means the pulp content based on the total mass of the pulp suspension. In addition, the nanocellulose concentration means the content of nanocellulose based on the total mass of the nanocellulose aqueous suspension.

The viscosity of the nanocellulose aqueous suspension is preferably 0.1 to 100 Pa·s. This makes it easier to mix the nanocellulose aqueous dispersion with the alkali-neutralized modified polyolefin aqueous emulsion. From this point of view, the viscosity of the nanocellulose aqueous dispersion is more preferably 0.1 to 10 Pa·s, further preferably 0.1 to 1 Pa·s. The viscosity of the nanocellulose aqueous dispersion is a value measured using a rotational viscometer (BM type) under conditions of a temperature of 25° C. and a rotation speed of 60 rpm.

For an aqueous suspension of nanocellulose, the particle diameter at which the cumulative value in the volume-based particle size distribution (pseudo particle size distribution) measured by a laser diffraction/scattering particle size distribution analyzer is 10% is the 10% cumulative particle diameter (D ₁₀ ), the particle diameter at which the cumulative value is 50% is the 50% cumulative particle diameter ( _D50 ), and the particle diameter at which the _cumulative value is 90% is the 90% cumulative particle diameter ( _D90 ). It is preferably 0.1-20 μm, with a D ₅₀ of 5.0-40 μm and a D ₉₀ of 20-150 μm. D ₁₀ is more preferably 1.0 to 15 μm, even more preferably 3.0 to 10 μm. D ₅₀ is more preferably 10-30 μm, more preferably 12-20 μm. D ₉₀ is more preferably 30-100 μm, even more preferably 50-80 μm. Since nanocellulose has a fibrous or acicular form, the above particle size distribution is a pseudo particle size distribution in which nanocellulose is simulated to have a particle form.

The aqueous suspension of nanocellulose obtained after defibration treatment of the pulp suspension is used as it is as the aqueous dispersion of nanocellulose described above, and mixed with an aqueous emulsion of modified polyolefin neutralized with alkali. You may Preferably, the nanocellulose aqueous suspension is diluted with water and stirred with the above-described stirrer or the like, and the obtained nanocellulose aqueous dispersion is used as the nanocellulose aqueous dispersion. Good to mix with an emulsion. The nanocellulose concentration in the nanocellulose aqueous dispersion when mixed with the modified polyolefin aqueous emulsion is preferably 0.1 to 5% by mass, more preferably 0.1 to 3% by mass, More preferably, it is 0.1 to 1% by mass.

As described above, by using a modified polyolefin having a carboxyl group, an aqueous emulsion obtained by neutralizing the modified polyolefin with an alkali, and an aqueous dispersion of nanocellulose, a treated product of a hydrous cellulose resin can be obtained by a simple method. be able to. Various additives may be used, for example, in the step of precipitating the modified polyolefin by adding an acid in the production of the treated product of the hydrous cellulose resin. Examples of additives include antioxidants, surfactants, light stabilizers, ultraviolet absorbers, antistatic agents, and conductive agents. One of the additives may be used alone, or two or more of them may be used in combination. Moreover, in the easily dispersible nanocellulose (B) obtained by the production of the hydrous cellulose resin-treated product, the additive may be compounded with the easily dispersible nanocellulose (B). Therefore, the treated product of hydrous cellulose resin and the easily dispersible nanocellulose (B) contained therein may contain the various additives described above in addition to the nanocellulose and the modified polyolefin.

(Method for producing resin composition)
As described above, in the method for producing a resin composition according to one embodiment of the present invention, the above-described hydrous cellulose resin-treated product and the thermoplastic resin (A) are heated at a temperature not higher than the boiling point of water +20°C to obtain a thermoplastic resin composition. It includes mixing the resin (A) in a molten state. Moreover, this production method includes removing water in the mixture of the treated hydrous cellulose resin and the thermoplastic resin (A) by heating at a temperature equal to or higher than the boiling point of water.

Since the boiling point of water is about 100°C at 1 atmosphere, when the hydrous cellulose resin-treated product and the thermoplastic resin (A) are mixed, they should be heated at 1 atmosphere to 120°C (boiling point of water 100°C + 20°C) or less. can be heated and mixed at a temperature of Further, when removing water from the mixture of the hydrous cellulose resin-treated product and the thermoplastic resin (A), the mixture can be heated at a temperature of 100° C. or higher at 1 atm. References to temperature herein are to temperatures under 1 atmosphere unless otherwise specified.

When the hydrous cellulose resin-treated product and the thermoplastic resin (A) are mixed, the amounts of the hydrous cellulose resin-treated product and the thermoplastic resin (A) used are determined according to the nanocellulose content in the resulting resin composition. It is preferable that the amount is within the range. Further, when the hydrous cellulose resin-treated product and the thermoplastic resin (A) are mixed, the thermoplastic resin (A) is mixed in a molten state. It is preferably above the melting point. The upper limit of the temperature during mixing is preferably the boiling point of water + 10 ° C. or less (110 ° C. or less), more preferably the boiling point of water + 5 ° C. or less (105 ° C. or less), and the boiling point of water or less (100 ° C. below) is more preferable. By setting the temperature within the above range, it becomes easier to suppress the evaporation of water and to more favorably disperse the treated product of the hydrous cellulose resin in the thermoplastic resin (A).

The time for mixing the treated product of hydrous cellulose resin and the thermoplastic resin (A) is not particularly limited, and can be appropriately determined according to the type and scale of the mixer that can be used for mixing, the amount of mixing, and the like. When a suitable mixer is used to produce a resin composition with relatively high productivity, the mixing time is preferably 5 to 60 minutes, more preferably 10 to 40 minutes, and 15 minutes. ~30 minutes is even more preferred. Suitable mixers include, for example, mixing rolls, Banbury mixers, kneaders, kneader ruders, single screw extruders, multi-screw extruders, and the like. Among these, it is more preferable to use a kneader.

After sufficiently mixing the treated product of hydrous cellulose resin and the thermoplastic resin (A), the temperature for removing the water in the mixture is the boiling point of water (100° C.) or higher. The temperature may be the same as the temperature during mixing, or may be adjusted as appropriate. The temperature at which water is removed from the mixture is preferably 105° C. or higher, more preferably 110° C. or higher, and even more preferably 120° C. or higher. The upper limit of the temperature when removing water is not particularly limited, but from the economical point of view of suppressing thermal energy due to heating, it is preferably 200° C. or less, more preferably 180° C. or less, and 150° C. or less. is more preferred.

The heating for removing the water in the mixture may be performed on the mixture taken out from the mixer, or may be performed on the mixture in the mixer. Preferably, after mixing the hydrous cellulose resin-treated product and the thermoplastic resin (A) in a molten state by heating at a temperature not higher than the boiling point of water +20°C in a mixer for a predetermined time. , the temperature of the mixer can be set to a temperature above the boiling point of water to remove the water in the mixture. In this case, even when water is removed, it is more preferable to continue mixing in the mixer until the generation of water vapor is stopped, because the mixture is quickly dried.

According to the above-described production method, it is possible to produce a resin composition in which the nanocellulose is excellent in dispersibility in the thermoplastic resin (A) and the generation of nanocellulose aggregates is suppressed in a simpler method. When producing the resin composition, components other than the above-described thermoplastic resin (A) and easily dispersible nanocellulose (B) may be used. Other components include, for example, colorants such as pigments and dyes, compatibilizers, antioxidants, light stabilizers, surfactants, metal powders, plasticizers, fragrances, ultraviolet absorbers, leveling agents, conductive materials, Also, antistatic agents and the like can be mentioned. One of them may be used alone, or two or more thereof may be used in combination. Therefore, the resin composition may contain the above other components in addition to the thermoplastic resin (A) and the easily dispersible nanocellulose (B).

[Example of how to use the resin composition]
In one aspect, the resin composition can be used after being molded into a sheet or pelletized by a pelletizer. A sheet-like or pellet-like resin composition is preferable because it can be used in combination with other resins. Thus, the resin composition is preferably used by being mixed with a thermoplastic resin (C) different from the thermoplastic resin (A) described above, and the masterbatch mixed with the thermoplastic resin (C) is more preferable. The resin composition is used as a masterbatch or the like by being mixed with another thermoplastic resin (C), so that the resin composition after being mixed with the thermoplastic resin (C) (hereinafter, "mixed resin composition" ) can be obtained. Further, the thermoplastic resin in the resin composition may further contain a thermoplastic resin (C) different from the thermoplastic resin (A), that is, the resin composition of one embodiment of the present invention has the above may be a mixed resin composition.

The resin composition is used by being mixed with a thermoplastic resin (C) different from the thermoplastic resin (A), so that even in the above mixed resin composition, the nanocellulose is excellent in dispersibility, and the nanocellulose is dispersed. It is possible to suppress the generation of aggregates. As a result, in the mixed resin composition, tensile strength, bending strength, compressive strength, shear strength, impact strength, toughness, etc. are improved compared to the thermoplastic resin (A) and the thermoplastic resin (C). Improvement in mechanical properties can be expected.

The content of the thermoplastic resin (C) in the mixed resin composition is preferably 20 to 500 parts by mass with respect to 100 parts by mass of the resin composition before containing the thermoplastic resin (C). It is more preferably up to 450 parts by mass, and even more preferably 40 to 400 parts by mass. The content of the thermoplastic resin (C) in the mixed resin composition is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, based on the total mass of the mixed resin composition. , 30 to 70% by mass. The content of nanocellulose in the mixed resin composition is preferably 0.1 to 20% by mass, more preferably 0.5 to 15% by mass, based on the total mass of the mixed resin composition. , more preferably 1 to 15% by mass.

[Thermoplastic resin (C)]
As the thermoplastic resin (C), a thermoplastic resin other than the thermoplastic resin (A), that is, a thermoplastic resin (C) having a melting point of more than 110°C can be used. Examples of such thermoplastic resins (C) include polyolefin resins such as polyethylene, polypropylene, copolymers of ethylene and/or propylene and α-olefin; nylon 6, nylon 11, nylon 12, nylon 66, and the like. polystyrene resins such as polystyrene; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polylactic acid; polycarbonate resins; cellulose resins such as triacetylated cellulose and diacetylated cellulose; acrylic resin; and the like. As described above, the thermoplastic resin (A) is preferably a polyolefin resin, and the thermoplastic resin (C) is also preferably a polyolefin resin because of good compatibility therewith.

In addition, as described above, an embodiment of the present invention can have the following configuration.
[1] A thermoplastic resin and an easily dispersible nanocellulose (B) dispersed in the thermoplastic resin are contained, and the easily dispersible nanocellulose (B) comprises nanocellulose and the nanocellulose. and a modified polyolefin having a carboxyl group, wherein the thermoplastic resin comprises a thermoplastic resin (A) having a melting point of 110° C. or lower.
[2] The melt flow rate (MFR) of the thermoplastic resin (A) measured in accordance with ASTM D1238 is 500 g/10 min or less under conditions of a temperature of 190 ° C. and a load of 2.16 kg. 1].
[3] The resin composition according to [1] or [2] above, wherein the modified polyolefin has a melting point of 100° C. or lower.
[4] The resin composition according to any one of [1] to [3] above, wherein the absolute value of the difference between the melting point of the thermoplastic resin (A) and the melting point of the modified polyolefin is 30°C or less.
[5] Any of the above [1] to [4], wherein the content of the nanocellulose in the easily dispersible nanocellulose (B) is 25% by mass or less based on the total mass of the resin composition The described resin composition.
[6] The resin composition according to any one of [1] to [5] above, wherein the nanocellulose contains cellulose nanofibers.
[7] The resin composition according to any one of [1] to [6] above, wherein the thermoplastic resin (A) contains a metallocene-based polyolefin resin.
[8] The resin composition according to any one of [1] to [7], which is used by being mixed with a thermoplastic resin (C) different from the thermoplastic resin (A).
[9] The resin composition according to any one of [1] to [7] above, wherein the thermoplastic resin further contains a thermoplastic resin (C) different from the thermoplastic resin (A).
[10] An easily dispersible nanocellulose (B) containing nanocellulose and a modified polyolefin having a carboxy group enveloping the nanocellulose and a hydrous cellulose resin treated product containing water, and a thermoplastic having a melting point of 110°C or less The resin (A) is heated at a temperature not higher than the boiling point of water by 20° C. and mixed in a molten state of the thermoplastic resin (A); A method for producing a resin composition, comprising removing water from a mixture of the treated resin and the thermoplastic resin (A).
[11] The melt flow rate (MFR) of the thermoplastic resin (A) measured in accordance with ASTM D1238 is 500 g/10 min or less under conditions of a temperature of 190°C and a load of 2.16 kg. 10].
[12] The method for producing a resin composition according to the above [10] or [11], wherein the modified polyolefin has a melting point of 100°C or lower.
[13] Production of the resin composition according to any one of the above [10] to [12], wherein the absolute value of the difference between the melting point of the thermoplastic resin (A) and the melting point of the modified polyolefin is 30°C or less. Method.
[14] When using the treated product of hydrous cellulose resin, an acid is added to a mixed dispersion of the aqueous dispersion of nanocellulose and the aqueous emulsion of the modified polyolefin neutralized with an alkali to convert the modified polyolefin. Precipitating and enveloping the nanocellulose with the modified polyolefin precipitated in the mixed dispersion to produce the hydrous cellulose resin-treated product according to any one of the above [10] to [13]. A method for producing a resin composition of
[15] In using the aqueous dispersion of nanocellulose, the aqueous suspension of nanocellulose is obtained by grinding a suspension containing pulp and water with a grinder to defibrate the pulp. A method for producing the resin composition according to [14] above, comprising producing.
[16] The method for producing a resin composition according to [15] above, wherein the grinder is a stone grinder.
[17] The viscosity of the aqueous suspension of nanocellulose is 0.1 to 100 Pa s as measured using a rotational viscometer under conditions of a temperature of 25 ° C. and a rotation speed of 60 rpm [15] ] or the method for producing a resin composition according to [16].
[18] For the aqueous suspension of nanocellulose, the particle diameter at which the cumulative value in the volume-based particle size distribution measured by a laser diffraction/scattering particle size distribution measuring device is 10% is the 10% cumulative particle diameter (D ₁₀ ), when the particle diameter at which the cumulative value is 50% is 50% cumulative particle diameter (D ₅₀ ), and the particle diameter at which the cumulative value is 90% is 90% cumulative particle diameter (D ₉₀ ), D ₁₀ is 0.1 to 20 μm, D ₅₀ is 5.0 to 40 μm, and D ₉₀ is 20 to 150 μm.

EXAMPLES The present invention will be specifically described below based on Examples, but the present invention is not limited to these Examples.

<Preparation of aqueous suspension of cellulose nanofibers>
6092.0 parts by weight of water is added to 100.0 parts by weight of high whiteness bleached kraft pulp (kappa number: less than 2, moisture: 7.0% by weight) with low lignin content, and the pulp concentration is 1.5. A slurry-like pulp suspension having a mass % content was prepared and allowed to stand and immerse for two days. The obtained pulp suspension is mechanically fibrillated with a stone grinder (trade name “Super Mascolloider”, manufactured by Masuko Sangyo Co., Ltd.) with two types of grindstones for a total of 8 passes. , the pulp was defibrated to the nanosize level to obtain an aqueous suspension of cellulose nanofibers (CNF) having a nanosize fiber width. The content of CNF in this water suspension is 1.5% by mass.

The resulting CNF aqueous suspension had a viscosity of 0.40 Pa·s measured using a BM-type rotational viscometer at a temperature of 25°C and a rotation speed of 60 rpm. In addition, the volume-based particle size distribution (pseudo particle size distribution) of the CNF aqueous suspension was measured using a laser diffraction/scattering particle size distribution analyzer (trade name “MT3300” manufactured by Nikkiso Co., Ltd.). As a result, D10 was 6.6 μm, _D50 was 15.8 μm, and _D90 was _60.8 μm.

<Production of easily dispersible nanocellulose and hydrous cellulose resin treated product>
(Production example 1)
To 250.0 parts by mass of the above CNF aqueous suspension, 500.0 parts by mass of ion-exchanged water was added, stirred at 5000 rpm for 30 minutes with a homomixer, and then at 600 rpm with a disper equipped with a water bath. for 30 minutes to obtain an aqueous dispersion of CNF. The content of CNF in this aqueous dispersion is 0.5% by mass.

Next, 15.0 parts by mass of an aqueous emulsion of a modified polyolefin having a carboxyl group (solid content: 25.0% by mass; hereinafter sometimes referred to as "POE-1") neutralized with sodium hydroxide is added to the aqueous dispersion of CNF (750.0 parts by mass), stirred at 3000 rpm for 50 minutes using a homomixer, then stirred at 1500 rpm for 30 minutes using a disper equipped with a water bath, A mixed dispersion was obtained. At this time, the pH of the mixed dispersion was 8.5. A commercially available product was used as the POE-1 before neutralization. The modified polyolefin having a carboxyl group in POE-1 is a polypropylene-type modified polyolefin having a melting point of 75° C., an acid value of 35 mgKOH/g, and an average particle diameter (median diameter) determined by a dynamic light scattering particle size distribution analyzer. ) was 80 nm.

While stirring the mixed dispersion with a disper at a rotation speed of 1500 rpm, 1.0% by mass hydrochloric acid is gradually added to the mixed dispersion until the pH of the mixed dispersion reaches 2.3, thereby precipitating the modified polyolefin. let me At this time, an increase in viscosity was observed at around pH 5-6. Then, the mixture was heated to 60° C. in a water bath, stirred for 30 minutes, filtered by suction, and thoroughly washed with ion-exchanged water until the pH of the filtrate became neutral. In this way, easily dispersible nanocellulose in a form in which the modified polyolefin precipitated in the mixed dispersion envelops CNF (hereinafter sometimes referred to as "CP-1"), and a paste containing water 20.8 parts by mass of a hydrous cellulose resin-treated product was obtained. When the solid content (CP-1) of this hydrous cellulose resin treated product was measured, it was 35.0% by mass. The solid content of the hydrous cellulose resin-treated material is the value when it reaches a constant weight at 130° C. with an infrared moisture meter. The CNF content in the solid content (CP-1) of the hydrous cellulose resin treated material is 50.0% by mass, and the CNF content in the hydrous cellulose resin treated material is 17.5% by mass.

(Production example 2)
Instead of POE-1 used in Production Example 1, an aqueous emulsion of modified polyolefin having a carboxyl group neutralized with sodium hydroxide (solid content: 25.0% by mass; hereinafter referred to as "POE-2" .)It was used. A commercially available product was used as the POE-2 before neutralization. The modified polyolefin having a carboxyl group in POE-2 was polypropylene type modified polyolefin, and had a melting point of 155° C., an acid value of 20 mgKOH/g, and an average particle size of 45 nm. Easily dispersible nanocellulose (hereinafter sometimes referred to as "CP-2") was prepared in the same manner as in Production Example 1, except that POE-1 used in Production Example 1 was changed to POE-2. and a hydrous cellulose resin-treated material containing water was obtained. The solid content (CP-2) of this hydrous cellulose resin treated product was 35.0% by mass. The CNF content in the solid content (CP-2) of the hydrous cellulose resin treated material is 50.0% by mass, and the CNF content in the hydrous cellulose resin treated material is 17.5% by mass.

<Production of resin composition>
(Example 1)
85.7 parts by mass (solid content: 30.0 parts by mass) of the hydrous cellulose resin-treated product (solid content (CP-1): 35 mass%) obtained in Production Example 1, and the thermoplastic resin (A) having a melting point of 80 ° C., MFR of more than 1000 g/10 min (190 ° C./2.16 kg), and a metallocene-based polyolefin resin having a weight-average molecular weight (Mw) of 45000 (trade name “Elmodu S400”, manufactured by Idemitsu Kosan Co., Ltd.; , Sometimes referred to as “PO-1”.) 70.0 parts by mass is placed in a desktop kneader (trade name “Plastograph”, manufactured by Brabender), and the thermoplastic resin ( Melt kneading was carried out in the molten state of A). Next, while heating to 130°C with a heater attached to the tabletop kneader, the blades in the tabletop kneader are rotated to dry until no more steam is generated (about 15 minutes). The water in the mixture with resin (A) was removed. In this way, a masterbatch (hereinafter sometimes referred to as “MB-1”) was obtained as a resin composition having a CNF content of 15.0% by mass.

(Example 2)
Instead of the hydrous cellulose resin-treated product (solid content: CP-1) used in Example 1, the hydrous cellulose resin-treated product (solid content: CP-2) obtained in Production Example 2 was used. Other than that, in the same manner as in Example 1, a masterbatch (hereinafter sometimes referred to as "MB-2") as a resin composition having a CNF content of 15.0% by mass is produced. did.

(Example 3)
As the thermoplastic resin (A), instead of the metallocene-based polyolefin resin (PO-1) used in Example 1, a melting point of 80 ° C. and an MFR of 25 g/10 min (190 ° C./2.16 kg), A metallocene-based polyolefin resin having a weight average molecular weight (Mw) of 130,000 (trade name “Elmodu S901” manufactured by Idemitsu Kosan Co., Ltd.; hereinafter sometimes referred to as “PO-2”) was used. Other than that, in the same manner as in Example 1, a masterbatch (hereinafter sometimes referred to as "MB-3") as a resin composition having a CNF content of 15.0% by mass is produced. did.

(Example 4)
As the thermoplastic resin (A), instead of the metallocene-based polyolefin resin (PO-1) used in Example 1, a resin having a melting point of 97° C. and an MFR of 3.6 g/10 min (190° C./2.16 kg) was used. A certain metallocene-based ethylene/α-olefin copolymer (trade name “Kernel KF370”, manufactured by Japan Polyethylene Co., Ltd.; hereinafter sometimes referred to as “PO-3”) was used. In addition, the temperature during melt-kneading using a desktop kneader was changed to 102°C. Other than that, the same method as in Example 1 was used to produce a masterbatch (hereinafter sometimes referred to as "MB-4") as a resin composition having a CNF content of 15.0% by mass. did.

(Example 5)
171.4 parts by mass (solid 60.0 parts by mass). Also, the amount of the metallocene-based polyolefin resin (PO-1) used in Example 1 was changed from 70.0 parts by mass to 40.0 parts by mass. Other than that, the same method as in Example 1 was used to produce a masterbatch (hereinafter sometimes referred to as "MB-5") as a resin composition having a CNF content of 30.0% by mass. did.

(Example 6)
As the thermoplastic resin (A), instead of the metallocene-based polyolefin resin (PO-1) used in Example 1, a low A density polyethylene resin (trade name “Novatec LD-LJ902”, manufactured by Japan Polyethylene Co., Ltd.; hereinafter sometimes referred to as “PO-4”) was used. In addition, the temperature during melt-kneading using a desktop kneader was changed to 110°C. Other than that, the same method as in Example 1 was used to produce a masterbatch (hereinafter sometimes referred to as "MB-6") as a resin composition having a CNF content of 15.0% by mass. did.

(Example 7)
171.4 parts by mass (solid 60.0 parts by mass). Further, as the thermoplastic resin (A), the same metallocene polyolefin resin (PO- 2) 40.0 parts by mass was used. Other than that, the same method as in Example 1 was used to produce a masterbatch (hereinafter sometimes referred to as "MB-7") as a resin composition having a CNF content of 30.0% by mass. did.

(Example 8)
Instead of the hydrous cellulose resin-treated product (solid content: CP-1) used in Example 1, the hydrous cellulose resin-treated product (solid content: CP-2) obtained in Production Example 2 was used. Further, as the thermoplastic resin (A), instead of the metallocene-based polyolefin resin (PO-1) used in Example 1, the same metallocene-based polyolefin resin (PO-2) used in Example 3 was used. . Other than that, the same method as in Example 1 was used to produce a masterbatch (hereinafter sometimes referred to as "MB-8") as a resin composition having a CNF content of 15.0% by mass. did.

(Comparative example 1)
Instead of the metallocene-based polyolefin resin (PO-1) used in Example 1, an acid-modified polypropylene resin (trade name " Yumex 1010", manufactured by Sanyo Chemical Industries; hereinafter sometimes referred to as "PO-5") was used. Also, the temperature during melt-kneading using a desktop kneader and during removal of water from the mixture was changed to 180°C. Other than that, the same method as in Example 1 was used to produce a masterbatch (hereinafter sometimes referred to as "MB-C1") as a resin composition having a CNF content of 15.0% by mass. did.

<Evaluation of Masterbatch>
A small amount of the masterbatch obtained in each example and comparative example is placed on a slide glass, and a hot plate is used to heat and melt the masterbatch on the slide glass. Then, a resin film composed of a masterbatch was obtained. Three resin films were produced for each type of masterbatch, and each resin film was magnified with an optical microscope to observe a region of 460 μm×620 μm. In this observation image, the number and size of aggregates were confirmed, and the average number of aggregates of 40 μm or more and aggregates of 100 μm or more was calculated for each type of masterbatch. The dispersibility of CNF in thermoplastic resin (A) was evaluated according to the standard. In the following evaluation criteria, "AA", "A", and "B" were judged to be acceptable, and "C" was judged to be unacceptable.
AA: The average number of aggregates of 40 µm or more is 5 or less, and the average number of aggregates of 100 µm or more is less than 1.
A: The average number of aggregates of 40 μm or more is more than 5 and 10 or less, and the average number of aggregates of 100 μm or more is less than 1.
B: The average number of aggregates of 40 μm or more is more than 10, and the average number of aggregates of 100 μm or more is less than 1.
C: The average number of aggregates of 100 μm or more is 1 or more.

Table 1 shows the components (solid content) and evaluation results of the masterbatch of each of the above examples and comparative examples.

<Production of mixed resin composition>
(Example 9)
The masterbatch (MB-1) obtained in Example 1 and the thermoplastic resin (C) were kneaded using a twin-screw extruder (manufactured by Shibaura Kikai Co., Ltd.) to produce a mixed resin composition. Specifically, 67 parts by mass of the masterbatch (MB-1) and 33 parts by mass of polypropylene (trade name “Prime Polypro J-106” manufactured by Prime Polymer Co., Ltd.) as the thermoplastic resin (C) are blended, Mixed. The mixed material was kneaded at a temperature of 200° C. by the twin-screw extruder, extruded into a rod shape (strand), and the extruded strand was cooled and cut with a pelletizer to obtain pellets. Thus, a pellet-shaped mixed resin composition having a CNF content of about 10% by mass was obtained.

(Example 10)
In the same manner as in Example 9 except that the masterbatch (MB-3) obtained in Example 3 was used instead of the masterbatch (MB-1) of Example 1 used in Example 9, A pellet-shaped mixed resin composition (CNF content: about 10% by mass) was obtained.

(Example 11)
In the same manner as in Example 9 except that the masterbatch (MB-4) obtained in Example 4 was used instead of the masterbatch (MB-1) of Example 1 used in Example 9, A pellet-shaped mixed resin composition (CNF content: about 10% by mass) was obtained.

(Example 12)
The masterbatch (MB-1) of Example 1 used in Example 9, the amount of 67 parts by mass thereof, and the amount of 33 parts by mass of the thermoplastic resin (C) were added to the masterbatch obtained in Example 7 ( MB-7) and its amount of use was changed to 33 parts by mass and the amount of thermoplastic resin (C) used was changed to 67 parts by mass, in the same manner as in Example 9, pelletized mixed resin composition (CNF content: about 10% by mass).

<Evaluation of mixed resin composition>
For the mixed resin compositions obtained in Examples 9 to 12, a test piece was prepared according to the provisions of ASTM D638 and subjected to a tensile test, and a test piece was prepared according to the provisions of ASTM D790. A bend test was performed. In the tensile test, using a precision universal testing machine (trade name "Autograph AG/X-R", manufactured by Shimadzu Corporation), tensile strength (maximum tensile stress) at room temperature (within the range of 20 to 25 ° C.) and tensile fracture strain were measured. In the bending test, bending strength (maximum bending stress) and bending elastic modulus were measured at room temperature (within the range of 20 to 25°C) using the precision universal testing machine. These results are shown in Table 2.

The tensile and bend tests described above were also carried out on Control Examples 9B, 10B, 11B, and 12B, which are blank tests corresponding to Examples 9, 10, 11, and 12, respectively. In Control Examples 9B to 12B, resin compositions (Control Example 9B ~ 12B mixed resin composition) was used. Specifically, in Reference Examples 9B to 12B, instead of using no masterbatch, the same type and amount of thermoplastic resin (A) as the thermoplastic resin (A) in the masterbatch used in the corresponding examples and the same amount of thermoplastic resin (C) as used in the corresponding example, and a pellet-shaped resin composition obtained by the same method as in Example 9 was used. Table 2 also shows the results of the blank test.

Furthermore, for the mixed resin compositions obtained in Examples 9 to 12, using an Izod impact tester (trade name "Impact Tester", manufactured by Toyo Seiki Seisakusho Co., Ltd.), test pieces were prepared according to the provisions of ASTM D256. was prepared and the Izod impact strength was measured. As a result, the Izod impact strength was 2.7 kJ/m 2 for Example 9, 6.5 kJ/m ² for Example 10, 20.3 kJ/m ² for Example 11, and 2.4 kJ/m ² for Example 12. was ^m2 .

Claims (18)

Containing a thermoplastic resin and easily dispersible nanocellulose (B) dispersed in the thermoplastic resin,
The easily dispersible nanocellulose (B) contains nanocellulose and a modified polyolefin having a carboxy group, which envelops the nanocellulose,
The thermoplastic resin includes a thermoplastic resin (A) having a melting point of 97° C. or less,
The thermoplastic resin (A) is a polyolefin resin,
The modified polyolefin is a resin composition having a melting point of 75 ° C. or lower. 2. The melt flow rate (MFR) of the thermoplastic resin (A) measured according to ASTM D1238 is 500 g/10 min or less under conditions of a temperature of 190° C. and a load of 2.16 kg. of the resin composition. The resin composition according to claim 1 or 2, wherein the content of said nanocellulose in said easily dispersible nanocellulose (B) is 30% by mass or less based on the total mass of said resin composition. The resin composition according to any one of claims 1 to 3, wherein the absolute value of the difference between the melting point of the thermoplastic resin (A) and the melting point of the modified polyolefin is 30°C or less. The resin composition according to any one of claims 1 to 4, wherein the content of the nanocellulose in the easily dispersible nanocellulose (B) is 25% by mass or less based on the total mass of the resin composition. thing. The resin composition according to any one of claims 1 to 5, wherein the nanocellulose contains cellulose nanofibers. The resin composition according to any one of claims 1 to 6, wherein the thermoplastic resin (A) contains a metallocene-based polyolefin resin. The resin composition according to any one of claims 1 to 7, which is used by being mixed with a thermoplastic resin (C) different from the thermoplastic resin (A). The resin composition according to any one of claims 1 to 7, wherein the thermoplastic resin further contains a thermoplastic resin (C) different from the thermoplastic resin (A). An easily dispersible nanocellulose (B) containing nanocellulose and a modified polyolefin having a carboxyl group enveloping the nanocellulose, a hydrous cellulose resin treated product containing water, and a thermoplastic resin (A ) at a temperature not higher than 20°C higher than the boiling point of water and mixed in the molten state of the thermoplastic resin (A); and removing the water in the mixture of said thermoplastic resin (A) ;
A method for producing a resin composition, wherein the thermoplastic resin (A) is a polyolefin resin . 11. The melt flow rate (MFR) of the thermoplastic resin (A) measured according to ASTM D1238 is 500 g/10 min or less under conditions of a temperature of 190° C. and a load of 2.16 kg. A method for producing a resin composition of The method for producing a resin composition according to claim 10 or 11, wherein the modified polyolefin has a melting point of 100°C or lower. The method for producing a resin composition according to any one of claims 10 to 12, wherein the absolute value of the difference between the melting point of the thermoplastic resin (A) and the melting point of the modified polyolefin is 30°C or less. In using the treated product of hydrous cellulose resin,
Acid is added to a mixed dispersion of the nanocellulose aqueous dispersion and the modified polyolefin aqueous emulsion neutralized with an alkali to precipitate the modified polyolefin, and the modified polyolefin precipitated in the mixed dispersion. Polyolefin enveloping the nanocellulose to produce the hydrous cellulose resin treated product;
A method for producing the resin composition according to any one of claims 10 to 13. In using the aqueous dispersion of the nanocellulose,
15. The resin composition according to claim 14, comprising producing an aqueous suspension of the nanocellulose by grinding a suspension containing pulp and water with a grinder to defibrate the pulp. manufacturing method. 16. The method for producing a resin composition according to claim 15, wherein the grinder is a stone grinder. 17. According to claim 15 or 16, the viscosity of the aqueous suspension of the nanocellulose is 0.1 to 100 Pa s as measured using a rotational viscometer under conditions of a temperature of 25° C. and a rotation speed of 60 rpm. A method for producing the described resin composition. For the aqueous suspension of the nanocellulose, the particle diameter at which the cumulative value in the volume-based particle size distribution measured by a laser diffraction/scattering particle size distribution analyzer becomes 10% is the 10% cumulative particle diameter (D ₁₀ ), When the particle diameter at which the cumulative value is 50% is 50% cumulative particle diameter (D ₅₀ ) and the particle diameter at which the cumulative value is 90% is 90% cumulative particle diameter (D ₉₀ ), D ₁₀ is 0. 1 to 20 μm, D ₅₀ is 5.0 to 40 μm, and D ₉₀ is 20 to 150 μm.