3d-printer molded object and method for producing same

Abstract

Provided are: a molded object having excellent strength and appearance and a method for producing same; and a resin composition and a 3D-printer molding material that yield such a molded object. In one embodiment, provided is a molded object that contains a thermoplastic resin and cellulose microfibers. The molded object is outputted by a 3D printer and has a section having a thickness of 2.5 mm or more. At least one cubic region measures 2 mm×2 mm×2 mm and is selected from the section having a thickness of 2.5 mm or more so as not to include the outermost layer of the molded object, said cubic region having a porosity of 10 vol% or less, as determined using an X-Ray computer tomographic (CT) method.

Description

3D printer modeling and its manufacturing method

[0001] The present invention relates to a 3D printer-modeled object containing a thermoplastic resin and cellulose microfibers, a method for producing the same, and the like.

[0002] 3D printers based on various modeling methods have been developed, including material extrusion deposition (MEX), stereolithography, material jetting, powder bonding, and powder bed fusion. 3D printer-generated objects are useful for prototyping due to their ease of production, and in recent years, they have also shown promise for use in commercial products. Meanwhile, due to the recent growing interest in environmental issues, efforts are being made to use environmentally friendly materials for 3D printers. For example, lightweight, bio-derived cellulose-based materials are useful as fillers to improve the physical properties of 3D printers. Cellulose microfibers, in particular, can impart excellent properties to 3D printers, such as high elasticity and dimensional stability during heating, thanks to their microstructure. However, in 3D printing using material extrusion deposition (MEX), for example, the flow behavior of the fluid must be appropriately controlled when the fluid is applied. However, controlling the flow behavior of filler-containing materials tends to be difficult. Therefore, various methods have been proposed for using a 3D printer to manufacture a shaped object that contains a filler such as cellulose microfiber and has intended characteristics (physical properties, etc.).

[0003] Patent Document 1 describes a modeling material for 3D printers, the modeling material comprising primarily a resin component consisting of (A) nanofibers, (B) a dispersant, and (C) a thermoplastic resin or photocurable resin. The technology described in Patent Document 1 aims to provide a modeling material for 3D printers that, by uniformly dispersing nanofibers such as cellulose nanofibers in the resin, improves strength and elastic modulus, enables more accurate reproduction of the designed shape as a modeled object, and produces three-dimensional models with excellent surface smoothness, transparency, and dyeability.

[0004] Patent Document 2 describes a resin composition for use as a modeling material in a fused deposition modeling 3D printer, characterized by containing cellulose fibers in a polyamide. The technology described in Patent Document 2 aims to provide a resin composition that has high heat resistance, can be used to model objects with the designed dimensions using a fused deposition modeling 3D printer, and has minimal warping after molding and minimal dimensional change due to water absorption.

[0005] Furthermore, a molding technology has been proposed for forming high-strength, high-definition objects using 3D printing.

[0006] Patent Document 3 describes a method for manufacturing a three-dimensional object by discharging molten thermoplastic resin from a discharge port and layering it on a base to form a three-dimensional object, the method comprising: a wall forming step in which the discharge port is moved relative to the base while discharging the molten thermoplastic resin to form a wall, thereby creating a space that is enclosed horizontally by the wall but open upward; and an injection step in which the molten thermoplastic resin is discharged from above the space and injected into the space. The technology described in Patent Document 3 aims to provide a method for forming a three-dimensional object with high shape accuracy and high strength using fused deposition modeling, which can prevent gaps from forming between layers of laminated material.

[0007] Patent Document 4 describes a method for manufacturing a three-dimensional object, including: a first step of forming a three-dimensional object on a modeling stage by fused deposition modeling under specific temperature conditions using a modeling material containing a crystalline thermoplastic resin as a main component; and a second step of peeling the three-dimensional object formed in the first step from the surface of the modeling stage under specific temperature conditions after the first step, wherein the crystalline thermoplastic resin is one selected from the group consisting of polyacetal resin, polyethylene resin, polypropylene resin, polyethylene terephthalate resin, polybutylene terephthalate resin, and polyamide resin. The technology described in Patent Document 4 aims to provide a method for manufacturing a three-dimensional object by fused deposition modeling, which uses a modeling material containing a crystalline thermoplastic resin as a main component, yet suppresses warping during stacking, firmly fixes the formed three-dimensional object to the modeling stage during modeling, and allows the formed three-dimensional object to be easily peeled from the modeling stage after formation.

[0008] Patent Document 5 describes a method for manufacturing a three-dimensional structure, which includes melting a filament containing a thermoplastic resin using a 3D printer and laminating it on a substrate, adhering one end of the filament to the surface of the substrate so that the adhesive strength with the substrate is 15 N or more, and ejecting the filament from a nozzle of the 3D printer onto the surface of the substrate while moving at least one of the substrate and the nozzle, and laminating it. The technology described in Patent Document 5 aims to provide a method for manufacturing a three-dimensional structure that can produce a three-dimensional structure with excellent shapeability.

[0009] JP 2017-170881 A, International Publication No. 2019 / 088014, JP 2018-86829 A, JP 2021-172084 A, International Publication No. 2017 / 126477

[0010] However, even with the techniques described in Patent Documents 1 to 5, it is still difficult to control the flow behavior of molding materials containing fillers, and stable production of molded objects with excellent strength and appearance has not yet been achieved.

[0011] One aspect of the present invention aims to solve the above-mentioned problems and to provide a molded object having excellent strength and appearance, a method for manufacturing the same, a resin composition that provides such a molded object, and a modeling material for 3D printers. Another aspect of the present invention aims to provide a method for manufacturing a 3D printer-modeled object that can stably produce a molded object having excellent strength and appearance.

[0012] The present disclosure includes the following items. [1] A shaped object comprising a thermoplastic resin and cellulose microfibers, the shaped object being an output product of a 3D printer, the shaped object having a portion with a thickness of 2.5 mm or more, and at least one 2 mm x 2 mm x 2 mm cubic region selected from the portion with a thickness of 2.5 mm or more has a porosity of 10 vol% or less as determined by X-ray computed tomography (CT). [2] The shaped object according to item 1, wherein the cubic region is a region selected so as not to include the outermost layer of the shaped object. [3] The shaped object according to item 1 or 2, wherein there are five of the at least one 2 mm x 2 mm x 2 mm cubic regions, and the number average value of the porosity for the five regions is 10 vol% or less. [4] The shaped object according to any one of items 1 to 3, wherein the thermoplastic resin includes a polyamide-based resin. [5] The shaped object according to any one of items 1 to 4, wherein the crystallinity of the shaped object measured using a differential scanning calorimeter (DSC) is 50% or less. [6] The shaped object according to any one of items 1 to 5, wherein the thermoplastic resin contains a crystalline resin having a melting point of 150°C to 300°C. [7] The shaped object according to any one of items 1 to 6, wherein the cellulose fine fibers have an average fiber diameter of 1,000 nm or less. [8] The shaped object according to any one of items 1 to 7, wherein the cellulose fine fibers are contained in an amount of 1 part by mass to 150 parts by mass per 100 parts by mass of the thermoplastic resin. [9] A method for producing the shaped object according to any one of items 1 to 8, comprising discharging a resin composition containing a thermoplastic resin and cellulose fine fibers from a discharge port of a 3D printer and laminating the resin composition.

[10] The method according to item 9, wherein the resin composition is supplied to the 3D printer as a filament-shaped 3D printing modeling material, and a melt of the 3D printing modeling material is discharged from the discharge outlet.

[11] A method for producing a shaped object comprising a thermoplastic resin and cellulose microfibers, the method comprising discharging a resin composition comprising a thermoplastic resin and cellulose microfibers from a discharge port of a 3D printer and laminating the resin composition, the shaped object having a portion with a thickness of 2.5 mm or more, and at least one 2 mm x 2 mm x 2 mm cubic region selected from the portion with a thickness of 2.5 mm or more has a porosity of 10 volume % or less as determined by X-ray computed tomography (CT).

[12] A method for producing a shaped object comprising a thermoplastic resin and cellulose microfibers, the method comprising discharging a resin composition comprising a thermoplastic resin and cellulose microfibers from a discharge port of a 3D printer and laminating the resin composition, the method comprising adjusting the temperature of the discharge port so that the resin composition is heated to a shear rate of 1000 s. -1 exhibiting a shear viscosity of less than 600 kPa.s at an elongation rate of 10 s -1

[13] A method for producing a shaped object containing a thermoplastic resin and cellulose fine fibers, comprising: discharging a resin composition containing a thermoplastic resin and cellulose fine fibers from a discharge port of a 3D printer and laminating the resin composition at a shear rate of 1000 s -1 The lowest temperature (T1) at which the resin composition exhibits a shear viscosity of 600 kPa.s or less is -1a maximum temperature (T2) at which the resin composition exhibits an extensional viscosity of 10 kPa s or more, and the difference between the temperature (T1) and the temperature (T2) is 40°C or more, and the temperature (T3) of the discharge port is set to be higher than the temperature (T1) and lower than the temperature (T2).

[14] The method according to item 12 or 13, wherein the molded object has a portion having a thickness of 2.5 mm or more, and at least one 2 mm x 2 mm x 2 mm cubic region selected from the portion having a thickness of 2.5 mm or more has a porosity of 10 vol% or less as determined by X-ray computed tomography (CT).

[15] The method according to any one of items 11 to 14, wherein the cubic region is a region selected so as not to include the outermost layer of the molded object.

[16] The method according to any one of items 11 to 15, wherein the resin composition is supplied to the 3D printer as a filament-shaped 3D printing material, and a molten product of the 3D printing material is discharged from the discharge port.

[17] The method according to any one of items 11 to 16, wherein the thermoplastic resin is one or more selected from the group consisting of polyamide-based resins and polyacetal-based resins.

[18] The method according to any one of items 11 to 17, wherein the thermoplastic resin comprises a polyamide-based resin.

[19] The method according to any one of items 11 to 18, wherein the crystallinity of the shaped object, measured using a differential scanning calorimeter (DSC), is 50% or less.

[20] The method according to any one of items 11 to 19, wherein the thermoplastic resin comprises a crystalline resin having a melting point of 150°C to 300°C.

[21] The method according to any one of items 11 to 20, wherein the cellulose fine fibers have an average fiber diameter of 1,000 nm or less.

[22] The method according to any one of items 11 to 21, wherein the resin composition comprises 1 part by mass to 150 parts by mass of the cellulose fine fibers per 100 parts by mass of the thermoplastic resin.

[23] The method according to any one of items 11 to 22, wherein the shaped object has an L value of 35 or more.

[24] A resin composition comprising a thermoplastic resin and cellulose fine fibers, wherein the resin composition is heated at a shear rate of 1000 s -1 The lowest temperature (T1) at which the resin composition exhibits a shear viscosity of 600 kPa.s or less is -1a resin composition, the temperature being lower than the highest temperature (T2) at which the elongational viscosity is 10 kPa s or more at 2000°C, and the difference between the temperature (T1) and the temperature (T2) is 40°C or more.

[25] The resin composition according to item 24, wherein the thermoplastic resin is one or more selected from the group consisting of polyamide-based resins and polyacetal-based resins.

[26] The resin composition according to item 24 or 25, wherein the thermoplastic resin comprises a crystalline resin having a melting point of 150°C to 300°C.

[27] The resin composition according to any one of items 24 to 26, wherein the cellulose fine fibers have an average fiber diameter of 1000 nm or less.

[28] The resin composition according to any one of items 24 to 27, wherein the resin composition comprises 1 part by mass to 150 parts by mass of the cellulose fine fibers per 100 parts by mass of the thermoplastic resin.

[29] A modeling material for 3D printing, which is a filament composed of the resin composition according to any one of items 24 to 28.

[30] The 3D printing modeling material according to item 29, having an L value of 35 or more.

[31] A modeled object produced by using a 3D printer to model the resin composition according to any one of items 24 to 28, or the 3D printing modeling material according to item 29 or 30.

[32] The modeled object according to item 31, having an L value of 35 or more.

[0013] According to one aspect of the present invention, there can be provided a shaped object having excellent strength and appearance, a method for manufacturing the same, a resin composition that provides such a shaped object, and a 3D printer modeling material. Also, according to another aspect of the present invention, there can be provided a method for manufacturing a 3D printer-modeled object that can stably produce a shaped object having excellent strength and appearance.

[0014] Fig. 1 is a diagram illustrating an example of the arrangement of blades and grooves of a disc refiner. Fig. 2 is a diagram illustrating the blade width, groove width, and inter-blade distance of a disc refiner. Fig. 3 is a diagram illustrating the dimensions of a dumbbell-shaped object. Fig. 4 is a diagram illustrating a three-dimensional image by X-ray CT of region 3 of Example A1. Fig. 5 is a diagram illustrating a three-dimensional image by X-ray CT of region 3 of Comparative Example A1.

[0015] The following describes exemplary embodiments of the present invention (hereinafter also referred to as the present embodiment), but the present invention is not limited to these embodiments and can be implemented in various modifications within the scope of its gist.

[0016] <<Shaped object and manufacturing method thereof>> One aspect of the present invention provides a shaped object comprising a thermoplastic resin and cellulose microfibers. In one aspect, the shaped object is an output product of a 3D printer. In one aspect, the shaped object has a portion with a thickness of 2.5 mm or more, and at least one 2 mm x 2 mm x 2 mm cubic region selected from the portion with a thickness of 2.5 mm or more (in one aspect, so as not to include the surface of the shaped object) has a porosity of 10 volume % or less. Another aspect of the present invention provides a method for manufacturing a shaped object comprising a thermoplastic resin and cellulose microfibers (the shaped object described above in one aspect), the method comprising ejecting a resin composition comprising a thermoplastic resin and cellulose microfibers from an ejection port of a 3D printer and laminating the resin composition. In one aspect of the method, the resin composition is supplied to the 3D printer as a filament-shaped 3D printing material, and a molten 3D printing material is ejected from the ejection port.

[0017] One aspect of the present invention provides a method for producing a shaped object containing a thermoplastic resin and cellulose fine fibers, which includes discharging and laminating a resin composition containing a thermoplastic resin and cellulose fine fibers from a discharge port of a 3D printer, and which satisfies the following (1) and / or (2): (1) The temperature of the discharge port is adjusted so that the resin composition (which is in the form of a 3D printer modeling material in one aspect; the same applies hereinafter) is heated at a shear rate of 1000 s -1 Shear viscosity is less than 600 kPa s and the elongation rate is 10 s -1 (2) The resin composition is heated to a temperature at which it exhibits an elongational viscosity of more than 10 kPa s at a shear rate of 1000 s -1 The lowest temperature (T1) at which the resin composition exhibits a shear viscosity of 600 kPa·s or less is the temperature at which the resin composition elongates at an elongation rate of 10 s -1 The temperature (T3) of the discharge port is set to be higher than the temperature (T1) and lower than the temperature (T2), and the difference between the temperature (T1) and the temperature (T2) is 40°C or more.

[0018] In this embodiment, the 3D printer is typically a material extrusion deposition (MEX) printer. The 3D printer may have a conventionally known configuration, and typically performs modeling according to the following procedure: 3D printer data is generated based on various three-dimensional data related to the desired shape of the object. Based on the 3D printer data, a modeling material, which is a resin composition, is ejected as a fluid and layered. In one aspect, the fluid is a molten resin composition modeling material. The fluid is ejected from the nozzle outlet onto the surface of a stage (i.e., a platform). The stage and / or the outlet is moved to move (typically, scan) the relative position between the outlet and the stage. This causes the fluid to be linearly deposited and layered. The deposited fluid solidifies to form a modeled object of the desired shape. The modeling material is typically a filament. In one aspect, the modeling material passes through a conveying section (e.g., a gear), is heated and melted in a heating section, is introduced into a nozzle, and is ejected from the nozzle outlet. The nozzle may be heated to a desired outlet temperature. The relationship between the shape of the object and the stacking direction may be appropriately designed depending on the intended use of the object. For example, the stage may be horizontal or inclined. If desired, a support material may be used to support the object.

[0019] The material of the stage surface can be appropriately selected depending on the material of the object to be molded, and may be an organic material (e.g., a resin-based material), an inorganic material (e.g., metal, glass, etc.), or a combination thereof. In one embodiment, the stage surface is made of a resin-based material, since the object, which is derived from a resin composition, adheres well to the stage during molding. The stage surface may be subjected to a surface treatment as needed.

[0020] The manner in which the discharge port is moved is not particularly limited and can be set appropriately depending on the purpose. For example, the frame of the shaped object may be formed first, and then the inside of the frame may be filled. The frame may be composed of, for example, one or two layers, but is not limited to this.

[0021] The strength and appearance of a molded object are significantly affected by the quality of the molding material as well as the uniformity of the laminate structure. The inventors have extensively studied the details of a desirable laminate structure that will result in a molded object with good strength and appearance, and as a result, have found that both the morphology between layers in the laminate structure and the morphology of the solidified material itself in each layer significantly contribute to strength and appearance. Specifically, the inventors have found that for a molded object containing a thermoplastic resin and cellulose microfibers, setting the porosity required by the method of this embodiment to a specific value or less is advantageous for achieving both high strength and good appearance.

[0022] Generally, when a modeling material containing a thermoplastic resin and a filler is ejected as a fluid from the nozzle of a 3D printer, interference between the fillers in the fluid tends to result in the solidified product containing voids. Such voids within the layers can deteriorate the strength and appearance of the modeled object. Furthermore, excessively low fluidity of the ejected fluid tends to result in poor interlayer adhesion due to poor wettability of the fluid to the surface of the formed layer, potentially resulting in voids between the layers. Poor interlayer adhesion, particularly voids between the layers, can also deteriorate the strength and appearance of the modeled object. On the other hand, modeling materials containing a thermoplastic resin and cellulose microfibers tend to have fewer voids in the solidified product due to less interference between the fillers. While the reasons for this are unclear, it is believed that the properties of cellulose microfibers, such as their fine structure and softness compared to inorganic fibers, contribute to this. Furthermore, interlayer adhesion tends to be improved if the fluid can be ejected at a lower viscosity. Modeling materials containing a thermoplastic resin and cellulose microfibers tend to offer greater flexibility in viscosity control through control of ejection conditions. Although the reason for this is unclear, it is presumed that the fact that a resin composition containing cellulose fine fibers is likely to exhibit thixotropy, etc., contributes to this. The present inventors have discovered that a shaped object having excellent strength and appearance can be provided by discharging a fluid of a shaping material containing a thermoplastic resin and cellulose fine fibers under controlled conditions to form a shaped object having the porosity of this embodiment.

[0023] <Porosity> In one aspect, the shaped object has a portion having a thickness of 2.5 mm or more, and at least one 2 mm x 2 mm x 2 mm cubic region selected from the portion having a thickness of 2.5 mm or more (in one aspect, so as not to include the outermost layer of the shaped object) has a porosity of 10 vol% or less as determined by X-ray computed tomography (X-ray CT).

[0024] X-ray CT scans a sample to obtain a tomographic image, construct a three-dimensional image from the tomographic image, and identify the target structural region through image analysis of the three-dimensional image. The volumetric porosity can be calculated by analyzing the numerical data for each voxel. In this embodiment, a 2 mm x 2 mm x 2 mm cubic region is evaluated as a region representative of the internal structure of the object, and voids present in the cubic region are identified through image analysis. Due to the principle of 3D printing, which involves linearly layering fluid to form an object, the porosity tends to vary significantly on the surface of the object due to the need to form the desired outer shape of the object. In one aspect, by evaluating a cubic region that does not include such surfaces and has a relatively large size of 2 mm per side, the obtained porosity value appropriately represents the internal structure of the object. Therefore, in one aspect, porosity comprehensively reflects the adhesion between layers and the uniformity within layers in the object, and can be a useful indicator of the strength and appearance of the object. In addition, the porosity can represent the internal structure of the object, and the object with a low porosity in this embodiment has good adhesion between layers and uniformity within the layers, and therefore can have excellent strength and appearance.

[0025] In one embodiment, the porosity is 10% by volume or less, or 9% by volume or less, or 8% by volume or less. A smaller porosity is advantageous, but from the viewpoint of ease of manufacturing a shaped object, in one embodiment, the porosity may be 1% by volume or more, or 1.5% by volume or more, or 2% by volume or more.

[0026] In one embodiment, when selecting a portion of the shaped object having a thickness of 2.5 mm or more, the selection is made so as not to include the outermost layer. Furthermore, when selecting cubic regions of 2 mm x 2 mm x 2 mm from a portion having a thickness of 2.5 mm or more, in one embodiment, the selection is made so as to represent the entire shaped object, depending on the shape of the shaped object. The number of cubic regions selected is a number appropriate for representing the entire shaped object. In one embodiment, the number of cubic regions selected may be 5 or more, and in one embodiment, 50 or less. For example, if the shaped object has a spur gear shape, a total of five cubic regions may be selected from the tooth tip, tooth base, hub, and rim (two selected from the tooth tip and one selected from the other). In one embodiment, the porosity is the number average value of each of the values ​​of the selected cubic regions. In one embodiment, the number of cubic regions is five, and the number average value of the porosity for the five regions is within the range exemplified above. A more detailed procedure for measuring the porosity is described in the [Examples] section of this disclosure.

[0027] The porosity can be adjusted by adjusting one or more of the factors exemplified in this disclosure regarding the composition of the resin composition and the modeling conditions of the 3D printer. In particular, good dispersion of the cellulose fine fibers in the resin composition and a fiber diameter of the cellulose fine fibers that is significantly smaller than the nozzle diameter can be advantageous for suppressing interference between the cellulose fine fibers in the fluid, and adjusting the shear viscosity can be advantageous for improving interlayer adhesion.

[0028] <Crystallization degree> The crystallinity of the shaped product, as measured by a differential scanning calorimeter (DSC), is preferably 50% or less, or 45% or less, or 40% or less, from the viewpoint of suppressing warpage during shaping. In one aspect, the crystallinity may be 10% or more, from the viewpoint of ease of production of the shaped product and strength of the shaped product. In one aspect, the crystallinity of the thermoplastic resin of this embodiment may be 50% or less, or 45% or less, or 40% or less, or may be 10% or more. In one aspect, the crystallinity of the polyamide-based resin may be in the above range. In one aspect, the crystallinity of the resin composition of this embodiment may be 50% or less, or 45% or less, or 40% or less, or may be 10% or more.

[0029] <Modeling Conditions> In the first aspect, from the viewpoint of reducing interlayer and intralayer voids in the modeled object, it is advantageous for the fluid discharged from the discharge port to have good fluidity (in one aspect, low viscosity). However, if the fluid has low viscosity, the following problems (1) and (2) may occur: (1) When the relative position of the discharge port with respect to the stage is moved while discharging is paused during modeling, the fluid drips from the discharge port, causing stringiness. This results in unwanted fluid adhering to the formed layer and causing defects such as fuzzing; and (2) When producing a filament-shaped modeling material from the resin composition, the resin composition drips undesirably under its own weight (i.e., drawdown), resulting in non-uniform filament diameters (i.e., non-uniform filament diameters due to repeated drawdown and subsequent thinning), which results in non-uniform heating of the filament during modeling and the formation of a non-uniform modeled object. Furthermore, in the second aspect, the strength and appearance of the modeled object are significantly affected by the uniformity of the layer structure in addition to the quality of the modeling material. Conventional techniques have been unable to consistently produce molded objects with excellent strength and appearance. The reasons for this include (1) and (2) above. Such stringing and drawdown can prevent the formation of a high-definition, uniform layered structure, which can deteriorate the strength and appearance of the molded object. To prevent stringing, a delivery gear at the back of the nozzle is usually rotated in the reverse direction when the discharge is interrupted, thereby retracting the molding material. However, even with this retraction, stringing may not be effectively prevented.

[0030] The inventors have found that, among the properties of the ejected fluid, extensional viscosity in particular contributes significantly to the degree of stringing and drawdown. When a fluid has a combination of a specific shear viscosity at a specific shear rate and a specific extensional viscosity at a specific extensional rate, the advantage of achieving both ease of modeling and suppression of stringing and drawdown is achieved. Regarding the stable production of shaped objects according to the second aspect, stringing and drawdown can be reduced by increasing the viscosity of the fluid, but fluids with excessively high viscosity are difficult to eject. It has been impossible to find molding conditions that suppress stringing and drawdown while maintaining ease of ejection (i.e., ease of modeling), or even if possible, it has required excessive trial and error. When the extensional viscosity is excessively low, it is difficult to reduce stringing and drawdown. When a fluid has a combination of a specific shear viscosity at a specific shear rate and a specific extensional viscosity at a specific extensional rate, the advantage of achieving both ease of molding and suppressing stringing and drawdown is obtained, which is advantageous for the stable production of shaped objects.

[0031] In one embodiment, the temperature of the discharge port is adjusted so that the resin composition is heated at a shear rate of 1000 s -1 In one embodiment, the temperature of the discharge port is set to a temperature at which the resin composition exhibits a shear viscosity of less than 600 kPa s at a shear rate of 1000 s. -1 exhibiting a shear viscosity of less than 600 kPa.s at an elongation rate of 10 s -1 The temperature is set to a value at which the elongational viscosity exceeds 10 kPa.s. -1 is an index of the shear rate applied to the fluid during discharge, and in order to stably discharge the fluid and accurately form a shaped object, it is advantageous that the shear viscosity at the shear rate is not too high. In one aspect, not having the shear viscosity be too high can be advantageous in terms of reducing interlayer and / or intralayer voids in the shaped object and achieving good strength and / or appearance. On the other hand, -1 is an index of the elongation rate applied to the fluid at the discharge port due to retraction when discharge is interrupted, and in order to suppress stringing and drawdown, it is advantageous that the elongation viscosity at the elongation rate is not too low. -1and exhibiting a shear viscosity of less than a predetermined value at an elongation rate of 10 s -1 When the resin composition is in a state where it exhibits an extensional viscosity exceeding a predetermined value at 200°C, the resin composition can exhibit the characteristics of being able to be stably discharged from a discharge port and being less susceptible to stringing or drawdown. The fact that a certain resin composition has a wide temperature range in which it can exhibit the above characteristics means that the resin composition can easily achieve easy modeling, suppression of stringing, and suppression of drawdown simultaneously without requiring strict control of modeling conditions (particularly temperature).

[0032] The resin composition was subjected to a shear rate of 1000 s -1 The minimum temperature (T1) at which the shear viscosity is 600 kPa s or less varies depending on the types and amounts of the thermoplastic resin, the cellulose fine fibers, and any additional components, but in one embodiment, it is 170°C or higher, or 180°C or higher, or 190°C or higher, and in another embodiment, it is 260°C or lower, or 250°C or lower, or 240°C or lower.

[0033] The resin composition has an elongation rate of 10 seconds. -1 The maximum temperature (T2) at which the elongational viscosity is 10 kPa s or more varies depending on the types and amounts of the thermoplastic resin, the cellulose fine fibers, and any additional components, but in one embodiment, it is 220°C or higher, or 230°C or higher, or 240°C or higher, and in another embodiment, it is 310°C or lower, or 300°C or lower, or 290°C or lower.

[0034] The temperatures (T1) and (T2) tend to be higher when the melting point of the thermoplastic resin is higher, when the molecular weight of the thermoplastic resin is higher, when the content of cellulose fine fibers is higher, and so on.

[0035] The resin composition was subjected to a shear rate of 1000 s -1 exhibiting a shear viscosity of less than 600 kPa.s at an elongation rate of 10 s -1The temperature of the discharge port, as the temperature at which the elongational viscosity exceeds 10 kPa s, varies depending on the types and amounts of the thermoplastic resin, the cellulose fine fibers, and any additional components, but in one aspect, it is 230°C or higher, or 235°C or higher, or 240°C or higher, and in another aspect, it is 300°C or lower, or 295°C or lower, or 290°C or lower. In one aspect, the temperature of the discharge port is controlled as the nozzle temperature. The number of discharge ports may be one or two or more, but is preferably one when forming a high-definition object.

[0036] In one embodiment, the resin composition is subjected to a shear rate of 1000 s -1 The lowest temperature (T1) at which the resin composition exhibits a shear viscosity of 600 kPa.s or less is the temperature at which the resin composition is stretched at an elongation rate of 10 s -1 The temperature (T1) is lower than the maximum temperature (T2) at which the resin composition exhibits an extensional viscosity of 10 kPa s or more when the extrusion temperature is appropriately controlled. When the extrusion temperature is appropriately controlled, such a resin composition can be stably extruded from the extrusion outlet and exhibits the characteristics of being less susceptible to stringing or drawdown. From the viewpoint of easily achieving ease of modeling, suppression of stringing, and suppression of drawdown simultaneously without requiring strict control of the modeling conditions (particularly temperature), a larger difference between the temperature (T1) and the temperature (T2) is advantageous, and in one aspect, the difference is 40°C or higher, or 45°C or higher, or 50°C or higher. From the viewpoint of ease of preparation of the resin composition, in one aspect, the difference may be 100°C or lower, or 90°C or lower, or 80°C or lower. In one aspect, the addition of cellulose fine fibers to a thermoplastic resin does not significantly change the shear viscosity, but tends to significantly increase the extensional viscosity. Therefore, combining cellulose fine fibers with a thermoplastic resin may be one factor in increasing the difference. Means for increasing the difference include reducing the fiber diameter of the cellulose fine fibers, dispersing the cellulose fine fibers more finely in the thermoplastic resin, and increasing the reinforcing properties of the cellulose fine fibers (for example, using a non-wood material such as cotton linter as the raw material for the cellulose fine fibers).

[0037] In one embodiment, the temperature (T3) of the discharge port is set to be higher than the temperature (T1) and lower than the temperature (T2). In this case, the ratio (T3-T1) / (T2-T1) varies depending on the types and amounts of the thermoplastic resin, the cellulose fine fibers, and any additional components, but in one embodiment, it may be 0.25 or more, or 0.3 or more, or 0.35 or more, and in one embodiment, it may be less than 1.0, or 0.95 or less, or 0.9 or less.

[0038] The shear viscosity and extensional viscosity are values ​​measured using a twin capillary rheometer. The shear viscosity and extensional viscosity of the resin composition may be considered to be the same for 3D printer modeling materials or models made from the resin composition. However, this does not apply to models that exhibit foaming.

[0039] The temperature of the discharge port is preferably at least 10°C, 15°C, or 20°C higher than the melting point of the thermoplastic resin if it is a crystalline resin, or the glass transition point of the thermoplastic resin if it is an amorphous resin (the highest value if multiple points are present in the resin composition) (also referred to as the melting temperature in the present disclosure), from the viewpoint of improving the strength of the shaped object by improving the adhesion between the fluid and the formed layer. From the viewpoint of preventing stringiness of the fluid and achieving a good appearance of the shaped object, the temperature of the discharge port is preferably at most 80°C, 70°C, or 60°C higher than the melting temperature. For example, when a resin composition having a melting temperature of 225°C is used, the temperature of the discharge port is preferably at least 235°C, 240°C, or 245°C, and preferably at most 305°C, 295°C, or 285°C.

[0040] The surface temperature of the stage is preferably 40°C or higher, or 50°C or higher, or 60°C or higher, from the viewpoint of preventing shrinkage of the molded object due to rapid cooling of the object by the stage, and from the viewpoint of preventing the molded object from falling during molding due to insufficient adhesion between the stage and the molded object, and is preferably 160°C or lower, or 140°C or lower, or 130°C or lower, from the viewpoint of not interfering with solidification of the first layer of the molded object (i.e., the portion in contact with the stage).

[0041] The outlet diameter may be designed appropriately depending on the type of molding material, the desired shape of the molded object, etc., and in one embodiment is 0.1 mm or more, or 0.2 mm or more, or 0.4 mm or more, and in another embodiment is 1.5 mm or less, or 1.0 mm or less, or 0.8 mm or less.

[0042] In one aspect, the modeling speed is the scanning speed of the position of the discharge port relative to the stage. The modeling speed may be designed appropriately depending on the type of modeling material, the desired shape of the model, etc., and may be 5 mm / sec or more, 8 mm / sec or more, or 10 mm / sec or more in one aspect, or 200 mm / sec or less, 100 mm / sec or less, or 50 mm / sec or less in one aspect. The scanning speed may be constant or may be changed appropriately depending on the part of the model. An example of the change is adjusting the modeling speed to suppress warpage and shrinkage in areas where warpage is likely to occur.

[0043] The layer height (layer pitch) may be appropriately designed depending on the type of modeling material, the desired shape of the object, etc. In terms of enabling rapid printing due to the small number of layers, it is preferably 0.1 mm or more, or 0.15 mm or more, or 0.2 mm or more, and in terms of enabling the formation of high-resolution objects, it is preferably 0.8 mm or less, or 0.6 mm or less, or 0.4 mm or less. In one aspect, the ratio of the layer pitch (mm) to the discharge orifice diameter (mm) may be 0.1 or more, or 0.25 or more, and in another aspect, it may be 1 or less, or 0.8 or less, or 0.6 or less.

[0044] Resin Composition A resin composition containing a thermoplastic resin and cellulose fine fibers may be used as a modeling material for a 3D printer for modeling. Preferred examples of the resin composition will be described below.

[0045] <Cellulose Microfibers> The cellulose microfibers of this embodiment may be unmodified or chemically modified. In one aspect, the cellulose microfibers are chemically modified cellulose microfibers. In this disclosure, chemically modified cellulose microfibers refer to cellulose microfibers in which at least a portion of the three hydroxyl groups contained in glucopyranose units in the backbone of the cellulose molecules present in the cellulose fibers have been chemically modified. Here, "at least a portion" refers to the fact that at least one hydroxyl group of at least one glucopyranose unit in a cellulose structure in which multiple glucopyranose units are polymerized has been chemically modified. In a typical aspect, the cellulose as a whole is not chemically modified, and the chemically modified cellulose microfibers retain the crystalline structure of the cellulose before chemical modification. For example, when analyzed by X-ray diffraction (XRD), the crystalline structure of cellulose type I can be confirmed.

[0046] [Cellulose raw material] The raw material for the cellulose fine fibers is not particularly limited, and wood-based cellulose raw materials (e.g., softwood chips and hardwood chips) or non-wood-based cellulose raw materials (cotton-derived, hemp-derived, bagasse-derived, kenaf-derived, bamboo-derived, straw-derived, seaweed-derived, algae-derived, sea squirt-derived, bacterial cellulose-derived, etc.) can be used. It is preferable to use cellulose raw materials with a high degree of type I crystallinity, such as so-called wood pulp such as softwood pulp and hardwood pulp, and non-wood pulp such as cotton linter pulp, hemp pulp, bagasse pulp, kenaf pulp, bamboo pulp, and straw pulp. In one embodiment, the cellulose fine fibers are derived from plants, in another embodiment, wood-derived, and in another embodiment, cotton-derived.

[0047] Furthermore, from the viewpoint of suppressing discoloration and deterioration of physical properties due to heat when compositing cellulose microfibers with a resin, the glucose content of the cellulose raw material as determined by constituent sugar analysis is preferably 90% by mass or more, more preferably 91% by mass or more, and even more preferably 93% by mass or more. The upper limit of the glucose content is not particularly limited, but taking into consideration the limits of impurities (e.g., components other than polysaccharides, such as oils and fats, various contaminants, etc.) that may be mixed into the cellulose raw material during harvesting or the purification process, or during the production process of cellulose microfibers, it is preferably 99.5% by mass or less. In a cellulose raw material, a high glucose content usually indicates high cellulose purity. Cellulose microfibers obtained using a cellulose raw material with high cellulose purity have the advantage of having low amounts of components that may reduce elastic modulus and heat resistance, such as alkali-soluble polysaccharides and acid-insoluble components.

[0048] The glucose content was measured by structural sugar analysis as follows. Structural sugar analysis was performed according to the analytical procedures of the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) (Sluiter, A., Hames, B., Ruiz, R., Scarlata, C., Sluiter, J., Templeton, D., Crocker, D.: Determination of structural carbohydrates and lignin in biomass. National Renewable Energy Laboratory (NREL), USA, 2008). 3 ml of 72% sulfuric acid was added to 200 mg of sample, and the mixture was allowed to swell at 30°C for 1 hour. The mixture was then poured into a 125 ml pressure bottle with 84 ml of pure water and hydrolyzed at 120°C for 1 hour. The mixture was then suction filtered while still hot through a 1G-3 glass filter (weighted at 105°C). After solid-liquid separation, the filtrate was adjusted to a constant volume of 100 ml, and the structural sugars were quantified by high-performance liquid chromatography (HPLC) (FL detection method).

[0049] The cellulose raw material may be purified. Examples of purified cellulose raw materials include purified pulp or cotton-like purified products obtained from the aforementioned cellulose raw materials, such as softwood chips, hardwood chips, or non-wood cellulose raw materials (such as those derived from cotton, hemp, bagasse, kenaf, bamboo, or straw), through a digestion process for delignification, a purification step for removing hemicellulose, and a bleaching process. Furthermore, cut yarns of regenerated cellulose fibers and cut yarns of regenerated cellulose obtained by electrospinning can also be used as purified cellulose raw materials. It is preferable to set appropriate purification treatment conditions (e.g., digestion temperature, alkali concentration during digestion, bleaching agent concentration, or bleaching time) depending on the type of cellulose raw material, produce purified cellulose fibers that retain high cellulose purity, and use them as the cellulose raw material.

[0050] From the viewpoints of high cellulose purity, industrial availability, and quality stability, cellulose fine fibers derived from cotton (cotton lint or cotton linter) are preferred, and cellulose fine fibers derived from cotton linter pulp are particularly preferred.

[0051] In response to recent demands for a sustainable society, recycled materials such as recycled cotton and recycled wood can also be used as cellulose raw materials. Recycled cotton, as used herein, refers to fibers made by collecting and shredding cotton scraps and cotton fluff discarded at spinning and sewing factories, or fibers obtained by shredding cotton that has been processed into cloth, clothing, etc. Furthermore, recycled wood refers to materials obtained by chipping sawmill waste, construction wood, thinned wood, forest residues, etc., and pulping them using conventional methods. Of the above-mentioned recycled materials, recycled cotton is preferred as the cellulose raw material of this embodiment.

[0052] Furthermore, it is effective to obtain cellulose fine fibers having excellent thermal stability by further immersing the unrefined cellulose raw material or the purified cellulose raw material (e.g., purified pulp) in water and subjecting it to a heat treatment at a temperature of 100°C or higher, or by subjecting the unrefined cellulose raw material or the purified cellulose raw material to an alkali treatment in which the raw material is immersed in a strong alkaline aqueous solution (alkali concentration: 1% by mass to 10% by mass) such as an aqueous sodium hydroxide solution, left to stand or stirred for a certain period of time at a temperature in the range of 0°C to 60°C, and then repeatedly washed with water.

[0053] In addition, it may also be effective to further immerse the unrefined cellulose raw material or purified cellulose raw material in water and subject it to an enzymatic treatment in which a hemicellulolytic enzyme such as xylases or mannanase or cellulases acts on it at a temperature in the range of 35°C to 55°C in order to obtain a highly purified cellulose raw material.

[0054] In particular, combining two or more of the above-mentioned heat treatment, alkali treatment, and enzyme treatment for purification can be effective for obtaining a purified cellulose raw material with a higher purity. These treatments can be significantly effective because they not only reduce the load of the pulverization treatment but also expel impurities such as lignin and hemicellulose present on the surfaces and between the microfibrils that constitute the cellulose raw material into the aqueous phase, thereby increasing the cellulose purity of the purified cellulose raw material.

[0055] The glucose content determined by the analysis of constituent sugars is preferably high not only in the cellulose raw material but also in the cellulose fine fibers. The glucose content of the cellulose fine fibers is preferably 85% by mass or more, more preferably 90% by mass or more, and although there is no particular upper limit, it is 99.5% by mass or less in one embodiment.

[0056] [Whiteness] The whiteness of the cellulose fine fibers of this embodiment is preferably 50% or more, or 60% or more, or 70% or more, or 80% or more, or 90% or more, or 95% or more. The whiteness here refers to the value measured using a spectrophotometer / color difference meter (for example, PF700 type manufactured by Nippon Denshoku Industries Co., Ltd.) according to the "Method for measuring ISO whiteness diffuse blue light reflectance of paper, paperboard and pulp (JIS P8148, ISO 2470)". When the cellulose raw material or cellulose fine fibers are obtained in sheet form, they are subjected to measurement as is. On the other hand, when in a wet state, the cellulose raw material or cellulose fine fibers are spun to a basis weight of 50 g / m. 2 As described above, paper is made using a suction filtration device equipped with a polytetrafluoroethylene (PTFE) membrane filter, and dried at 80 ° C until the moisture content reaches equilibrium to prepare a cellulose sheet, which is then used to measure whiteness using the above-mentioned device. The higher the whiteness, the better the heat resistance of the cellulose fine fibers, and therefore the strength, elastic modulus, and dimensional stability are improved when the resin composition obtained by compounding with a resin by melt kneading is mechanically recycled, which is preferable. The higher the whiteness of the cellulose fine fibers, the greater the effect, so there is no upper limit, but in one embodiment, the whiteness substantially obtained from the cellulose fine fibers is 99% or less.

[0057] One way to achieve the above-mentioned whiteness of the cellulose fine fibers is to subject the cellulose raw material to a treatment such as bleaching prior to the defibration treatment. In the defibration step of this embodiment, the whiteness usually does not decrease significantly, so the whiteness of the cellulose raw material subjected to defibration matches the whiteness of the cellulose fine fibers. Therefore, the whiteness of the cellulose raw material is preferably 50% or more, or 60% or more, or 70% or more, or 80% or more, or 90% or more, or 95% or more. The higher this value, the greater the effect, so there is no upper limit, but in one aspect the whiteness substantially obtained from the cellulose raw material is 99% or less.

[0058] [Fiber length distribution of cellulose raw material] In one aspect, the cellulose raw material has an average fiber length (specifically, a length-weighted average fiber length described below) of 3 mm or less as measured by an automatic fiber shape analyzer, and / or the number ratio of fibers having a fiber length of 3 mm or more is 20% or less. When the cellulose raw material has a specific fiber length distribution, energy transfer to the micronizing or beating section during the defibration step (for example, beating using a disc refiner or high-pressure homogenizer) is improved and clogging is less likely to occur, thereby achieving stable defibration processing even in a slurry containing cellulose at a relatively high concentration.

[0059] The average fiber length is more preferably 2.5 mm or less, even more preferably 2.0 mm or less, and particularly preferably 1.6 mm or less. The smaller the average fiber length, the greater the above-mentioned effect, so there is no particular lower limit, but in consideration of the mechanical properties when the cellulose fine fibers after beating are used as a filler, the average fiber length is preferably 0.1 mm or more, and more preferably 0.5 mm or more.

[0060] The proportion of fibers having a fiber length of 3 mm or more is more preferably 15% or less, and even more preferably 10% or less. The smaller this value, the greater the effect described above. Therefore, there is no particular lower limit, but a range of 0.5% or more is preferable, and 1% or more is more preferable as a range that can be obtained by practical pretreatment.

[0061] The fiber length of the above-mentioned cellulose raw material can be measured using an automatic fiber shape analyzer (Morfi Neo manufactured by Techpap). The measurement procedure is described below.

[0062] The cellulose raw material is dispersed in pure water to prepare 1 L of an aqueous dispersion. The final solids concentration of the cellulose raw material is 0.003 to 0.005% by mass. When the cellulose raw material is an aqueous dispersion containing less than 2% by mass before dilution, simple mixing with a spatula or the like is sufficient. However, when the cellulose raw material is an aqueous dispersion containing 2% by mass or more, or in the form of a wet cake or powder, a high-shear homogenizer (e.g., IKA, trade name "Ultra Turrax T18") is used to perform dispersion treatment under the following treatment conditions: a rotation speed of 25,000 rpm for 5 minutes. When the product is dispersed in a medium other than water, the product is dispersed in a sufficient amount of pure water using the high-shear homogenizer at a rotation speed of 25,000 rpm for 5 minutes, and the medium is then removed by means of suction filtration or the like. The product is then dispersed again using the high-shear homogenizer at a rotation speed of 25,000 rpm for 5 minutes in pure water to a final solids concentration of 0.003 to 0.005% by mass, thereby replacing the medium with water.

[0063] Next, the aqueous dispersion prepared above is subjected to an autosampler and measurements are performed. The measurement results obtained are output in txt format (or csv format), and each shape parameter is extracted or calculated from the measurement results. The following values ​​from the measurement results are used for each parameter.

[0064] 1) Length-weighted average fiber length: Mean length-weighted Length [μm] 2) Proportion of fibers with a fiber length of 3 mm or more: From the histogram of the fiber length distribution in 1), the proportion of the number of fibers with a fiber length of 3 mm or more to the total number of fibers is calculated using the following formula: Proportion of fibers with a fiber length of 3 mm or more (%) = Number of fibers with a fiber length of 3 mm or more / Total number of fibers measured × 100 3) Average fiber diameter: Mean fiber width [μm]

[0065] To control the fiber length of the cellulose raw material within a specific range, the cellulose raw material may be subjected to one or more pretreatments selected from pulverization, grinding, and classification, and then used for defibration (e.g., beating). One aspect of the pretreatment is a process for producing a pretreated cellulose raw material having an average fiber length of 3 mm or less and / or a fiber length of 3 mm or less of 20% or less from a cellulose raw material having an average fiber length of 3 mm or less, from the cellulose raw material having an average fiber length of more than 3 mm and a fiber length of more than 20%. The pulverization process is a process for dry-grinding the cellulose raw material, and a coarse grinder, intermediate grinder, fine grinder, or the like can be used as the grinding machine. The grinding process is a process for dispersing the cellulose raw material in an aqueous medium and grinding the resulting aqueous dispersion, and is distinguished from the above-mentioned grinding process in that it is a wet process. Examples of grinders include rotary mills, mortars, planetary mixers, single-screw extruders, twin-screw extruders, and bead mills. The classification process may be dry or wet classification. Dry classification includes gravity field classification, inertial field classification, and centrifugal field classification (natural vortex type or forced vortex type), while wet classification includes gravity field classification, centrifugal field classification (free vortex type), and centrifugal field classification (forced vortex type). Classification using the openings of sieves, screens, wires (edge ​​wires), nets, etc., and classification by centrifugal separation can also be used.

[0066] [Chemical modification] In one embodiment, the cellulose fine fibers are chemically modified cellulose fine fibers. The chemical modification may be carried out before, during, and / or after defibration, but in a preferred embodiment, the chemical modification is carried out in a state before defibration (in one embodiment, in a pulp state), and then the defibration treatment is carried out. When the above pretreatment is carried out before defibration, the chemical modification may be carried out before the pretreatment, but from the viewpoint of ease of processing, it is preferable to carry out the chemical modification after the pretreatment.

[0067] Chemical modification methods include esterification, etherification, and urethanization. Esterification is preferred from the viewpoint of obtaining chemically modified cellulose fine fibers with excellent heat resistance. Among these, saturated monocarboxylic acid esterification, such as acetate esterification (acetylation), propionate esterification, pentanoic acid (valeric acid) esterification, and hexanoic acid (caproic acid) esterification, is preferred. Among these, acetate esterification (acetylation) is preferred from the viewpoint of the heat resistance of the cellulose fine fibers after chemical modification. Esterification using a dicarboxylic acid, such as phthalic acid esterification, may also be used. In a preferred embodiment, the cellulose fine fibers are acetylated cellulose fine fibers. Examples of modifying agents include esterifying agents such as saturated carboxylic acids or their acid anhydrides or acid chlorides; and saturated monovinyl carboxylates, such as vinyl acetate and vinyl propionate.

[0068] The esterifying agent is not particularly limited, but examples thereof include aliphatic monocarboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, and isobutyric acid; alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid; aromatic monocarboxylic acids such as benzoic acid, toluic acid, α-naphthalenecarboxylic acid, β-naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, and phenylacetic acid; and a plurality of esterifying agents arbitrarily selected from the above. A mixture of these, a symmetric anhydride (acetic anhydride, maleic anhydride, cyclohexane-carboxylic anhydride, benzene-sulfonic anhydride), a mixed acid anhydride (butyric acid-valeric acid anhydride), a cyclic anhydride (succinic anhydride, phthalic anhydride, naphthalene-1,8:4,5-tetracarboxylic acid dianhydride, cyclohexane-1,2,3,4-tetracarboxylic acid 3,4-anhydride), an ester acid anhydride (acetic acid 3-(ethoxycarbonyl)propanoic acid anhydride, benzoylethyl carbonate), or the like arbitrarily selected from these is preferred.

[0069] When chemically modifying a cellulose raw material before defibration, in order to chemically modify the fibers inside the cellulose raw material, it is preferable to carry out the chemical modification in a solvent that effectively swells the cellulose raw material. In one embodiment, the solvent that effectively swells the cellulose raw material is an aprotic polar solvent, and preferred examples include dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and mixtures of two or more thereof.

[0070] In another embodiment, cellulose may be chemically modified after being converted into fine fibers. In this case, the cellulose fine fibers are concentrated by suction filtration or the like to form a wet cake, which is then diluted and dispersed in a solvent for chemical modification. The chemical modification method may be the same as that used for chemically modifying cellulose raw materials.

[0071] However, when chemically modifying cellulose fine fibers, excessive drying can cause aggregation of the cellulose fine fibers, so the solids concentration is preferably 30% by mass or less, more preferably 20% by mass or less. On the other hand, for example, in chemical modification using an esterifying agent, the esterifying agent reacts with water in addition to cellulose, so the less water carried over, the better, and the lower limit of the solids concentration is preferably 5% by mass or more, more preferably 10% by mass or more. If the presence of water makes chemical modification difficult, it is advisable to suction-filter the dispersion slurry diluted and dispersed in the above-mentioned solvent, and then repeatedly add solvent to reduce the water content in the system before carrying out chemical modification. Note that when chemically modifying a cellulose raw material after it has been microfibrillated, it is preferable to use a solvent that effectively swells the cellulose raw material as the solvent from the viewpoint of uniform chemical modification, but other solvents can also be used because the surface of the cellulose fine fibers is exposed.

[0072] (Degree of substitution (DS)) The degree of substitution (DS) of the cellulose raw material or cellulose fine fibers is preferably 0.5 or more, or 0.6 or more, or 0.7 or more. If the DS is too high, the crystallinity is low, and the mechanical properties of the resin composition obtained by combining the cellulose fine fibers with a resin tend to be low. Therefore, the DS is preferably 1.3 or less, or 1.1 or less, or 1.0 or less.

[0073] The degree of substitution (DS) can be determined as follows. The following description will be given taking the case where the chemical modification is esterification (acylation) as an example. The degree of acyl substitution can be calculated from the reflection infrared absorption spectrum of the esterified cellulose fiber based on the peak intensity ratio between the peak derived from the acyl group and the peak derived from the cellulose skeleton. The peak of the absorption band of C=O based on the acyl group is at 1730 cm -1 The peak of the absorption band of C—O based on the cellulose backbone appears at 1030 cm -1 The DS of the esterified cellulose fiber can be determined by preparing a correlation graph between the DS obtained from solid-state NMR measurement of the esterified cellulose fiber (described below) and the modification degree (IR index 1030), which is defined as the ratio of the peak intensity of the absorption band of C=O based on an acyl group to the peak intensity of the absorption band of C-O in the cellulose backbone chain, and using the calibration curve calculated from the correlation graph: Degree of substitution DS = 4.13 × IR index (1030)

[0074] The DS of esterified cellulose fibers by solid-state NMR was 13 C solid-state NMR measurement is performed, and DS can be calculated using the following formula, which is the ratio of the total area intensity (Inp) of signals assigned to carbon atoms C1-C6 derived from the pyranose ring of cellulose, which appear in the range of 50 ppm to 110 ppm, to the area intensity (Inf) of a signal assigned to one carbon atom derived from the modifying group: DS = (Inf) × 6 / (Inp).For example, if the modifying group is an acetyl group, the signal at 23 ppm assigned to -CH3 can be used.

[0075] Use 13 The conditions for C solid-state NMR measurement are, for example, as follows: Apparatus: Bruker Biospin Avance 500WB Frequency: 125.77 MHz Measurement method: DD / MAS method Waiting time: 75 sec NMR sample tube: 4 mmφ Number of accumulations: 640 (approximately 14 hours) MAS: 14,500 Hz Chemical shift reference: glycine (external reference: 176.03 ppm)

[0076] (DS of cellulose fine fibers s In one embodiment, the cellulose fine fibers may be cellulose fine fibers whose surfaces have been chemically modified. In one embodiment, the DS heterogeneity ratio (DSs / DS), defined as the ratio of the degree of substitution (DSs) of the fiber surface to the degree of substitution (DS) of the entire fiber of the chemically modified cellulose fine fibers, may be 1.05 or more.

[0077] The DS heterogeneity ratio (DSs / DS), defined as the ratio of the degree of substitution (DSs) at the fiber surface to the degree of substitution (DS) of the entire fiber, is preferably 1.05 or more. The larger the DS heterogeneity ratio, the more pronounced the sheath-core-like heterogeneous structure (i.e., a structure in which the fiber surface is highly chemically modified while the fiber center maintains a cellulose structure close to the original, unmodified structure). This allows for the high mechanical strength and dimensional stability inherent in cellulose to be maintained, while improving the affinity with resins when composited with resins and improving the dimensional stability of resin compositions. The DS heterogeneity ratio is more preferably 1.1 or more, or 1.2 or more, or 1.3 or more, or 1.5 or more, or 2.0 or more. From the viewpoint of ease of production of chemically modified cellulose fine fibers, it is preferably 30 or less, or 20 or less, or 10 or less, or 6 or less, or 4 or less, or 3 or less.

[0078] DS s The value of varies depending on the DS, but as an example, it is preferably 0.1 or more, or 0.2 or more, or 0.3 or more, or 0.5 or more, and preferably 3.0 or less, or 2.5 or less, or 2.0 or less, or 1.5 or less, or 1.2 or less, or 1.0 or less.

[0079] DSs is determined by the following method. Chemically modified cellulose fibers powdered by freeze-pulverization are placed on a 2.5 mm diameter dish-shaped sample stage, the surface is pressed down to flatten it, and then measurement is performed using X-ray photoelectron spectroscopy (XPS). The XPS spectrum reflects the constituent elements and chemical bonding state of only the surface layer of the sample (typically about a few nm). Peak separation is performed on the obtained C1s spectrum, and DSs can be calculated using the following formula, which is the integrated intensity (Ixf) of the peak assigned to one carbon atom derived from the chemical modifying group relative to the integrated intensity (Ixp) of the peak (289 eV, C-C bond) assigned to carbons C2-C6 derived from the pyranose ring of cellulose. DSs = (Ixf) x 5 / (Ixp) When the chemical modifying group is an acetyl group, after peak separation of the C1s spectrum at 285 eV, 286 eV, 288 eV, and 289 eV, the peak at 289 eV can be used for Ixp, and the peak (286 eV) derived from the O-C=O bond of the acetyl group can be used for Ixf. The XPS measurement conditions used are, for example, as follows. Instrument used: ULVAC-Phi VersaProbe II Excitation source: mono. AlKα 15 kV x 3.33 mA Analysis size: approximately 200 μmφ Photoelectron take-off angle: 45° Take-up area Narrow scan: C 1s, O 1s Pass Energy: 23.5 eV

[0080] [Crystallization degree] The crystallinity of the cellulose raw material or cellulose fine fibers is preferably 50% or more. When the crystallinity is within this range, the mechanical properties (strength, dimensional stability) of the cellulose itself are high, and therefore, when the cellulose fine fibers are dispersed in a resin, the strength and dimensional stability of the resin composition tend to be high. A more preferred lower limit of the crystallinity is 55% or more, or 60% or more, or 65% or more, or 70% or more, or 75% or more, and most preferably 80% or more. There is no particular upper limit for the crystallinity, and a higher value is preferable, but from the viewpoint of production, a preferred upper limit is 99%.

[0081] In the present disclosure, when the cellulose in a sample is cellulose type I crystals (derived from natural cellulose), the crystallinity can be determined by the Segal method from the diffraction pattern (2θ / deg. 10 to 30) obtained by measuring the sample by wide-angle X-ray diffraction, using the following formula: Crystallinity (%) = [I(200) -I (amorphous) ] / I (200) ×100 I (200) : Diffraction peak intensity due to the 200 plane (2θ = 22.5°) in cellulose type I crystal (amorphous) : The halo peak intensity due to amorphous in cellulose type I crystal, which is the peak intensity at an angle 4.5° lower than the diffraction angle of the 200 plane (2θ = 18.0°)

[0082] When the cellulose in the sample is cellulose type II crystal, the crystallinity can be calculated by the following formula using the absolute peak intensity h0 at 2θ=12.6° assigned to the (110) plane peak of cellulose type II crystal in wide-angle X-ray diffraction and the peak intensity h1 of the baseline (the line connecting 2θ=8° and 15°) at this interplanar spacing: Crystallinity (%) = (h0-h1) / h0 × 100

[0083] [Changes in the morphology of cellulose raw materials or cellulose fine fibers before and after chemical modification] In the chemical modification, the stirring conditions, temperature, etc. may be adjusted as appropriate, but the fiber length retention rate of the cellulose raw materials or cellulose fine fibers before and after chemical modification (fiber length retention rate (%) = average fiber length (nm) after modification / average fiber length (nm) before modification x 100) is preferably 70% or more, 80% or more, or 90% or more. When the retention rate is within the above range, the fiber length of the cellulose fine fibers is maintained long, and the strength and heat resistance of the resin composition are good. The higher the fiber length retention rate, the greater the effect, so there is no particular upper limit, but considering realistic modification treatments, 99.5% or less is preferred.

[0084] [Crystalline polymorphism] Types I, II, III, IV, etc. are known as crystalline polymorphs of cellulose, and among these, types I and II are particularly widely used, while types III and IV are obtained on a laboratory scale but are not widely used on an industrial scale. When the crystalline polymorphism of the cellulose fine fibers is type I or type II, the mechanical properties (strength, dimensional stability) of the fibers are high, and when the cellulose fine fibers are dispersed in a resin, the strength and dimensional stability of the resin composition are high, which is preferable.

[0085] [Degree of polymerization] The degree of polymerization of the cellulose raw material or cellulose fine fibers is preferably 100 or more, or 150 or more, or 200 or more, or 300 or more, or 400 or more, or 450 or more, and preferably 3500 or less, or 3300 or less, or 3200 or less, or 3100 or less, or 3000 or less.

[0086] From the viewpoint of processability and mechanical property expression, it is desirable that the degree of polymerization is within the above-mentioned range. From the viewpoint of processability, it is preferable that the degree of polymerization is not too high, and from the viewpoint of mechanical property expression, it is desirable that the degree of polymerization is not too low.

[0087] The degree of polymerization refers to the average degree of polymerization measured according to the reduced specific viscosity method using a copper-ethylenediamine solution as described in Verification Test (3) of the "Japanese Pharmacopoeia Commentary, 15th Edition (published by Hirokawa Shoten)." The degree of polymerization of chemically modified cellulose microfibers may not be accurately calculated due to the presence of chemically modifying groups. In this case, the degree of polymerization of the cellulose microfibers immediately before chemical modification, which are the raw material for the chemically modified cellulose microfibers, or the cellulose raw material immediately before chemical modification, may be considered to be the degree of polymerization of the chemically modified cellulose microfibers.

[0088] [Mw, Mn, Mw / Mn] In one embodiment, the weight average molecular weight (Mw) of the cellulose fine fibers is preferably 100,000 or more, or 120,000 or more, or 150,000 or more, or 180,000 or more, or 200,000 or more. In one embodiment, the number average molecular weight (Mn) of the cellulose fine fibers is preferably 10,000 or more, or 12,000 or more, or 15,000 or more, or 17,000 or more, or 18,000 or more, or 20,000 or more, or 25,000 or more, or 30,000 or more. In one embodiment, the ratio of the weight average molecular weight to the number average molecular weight (Mn) (Mw / Mn) is preferably 10.0 or less, or 9.0 or less, or 8.0 or less, or 7.0 or less, or 6.0 or less, or 5.6 or less, or 5.4 or less. A higher weight average molecular weight means a lower number of end groups in the cellulose molecules. Furthermore, since the ratio of weight-average molecular weight to number-average molecular weight (Mw / Mn) represents the width of the molecular weight distribution, a smaller Mw / Mn means fewer ends of cellulose molecules. Since the ends of cellulose molecules serve as the starting point for thermal decomposition, cellulose fine fibers with particularly high heat resistance can be obtained when the cellulose molecules of the cellulose fine fibers not only have a high weight-average molecular weight but also have a narrow molecular weight distribution. From the viewpoint of the availability of cellulose raw materials, the weight-average molecular weight (Mw) of the cellulose fine fibers may be, for example, 1,000,000 or less, or 800,000 or less, or 600,000 or less, or 500,000 or less, or 400,000 or less. From the viewpoint of the availability of cellulose raw materials, the number-average molecular weight (Mn) of the cellulose fine fibers may be, for example, 600,000 or less, or 500,000 or less, or 400,000 or less. From the viewpoint of ease of production of cellulose fine fibers, the ratio of weight average molecular weight to number average molecular weight (Mn) (Mw / Mn) may be, for example, 1.5 or more, or 1.7 or more, or 2 or more. Mw can be controlled within the above range by selecting a cellulose raw material having an Mw appropriate for the purpose, by subjecting the cellulose raw material to appropriate physical treatment and / or chemical treatment within an appropriate range, and particularly by performing defibration under controlled, mild conditions.The Mw / Mn can also be controlled within the above range by selecting a cellulose raw material with an Mw / Mn appropriate for the purpose, by subjecting the cellulose raw material to appropriate physical and / or chemical treatment within an appropriate range, and particularly by performing defibration under controlled, mild conditions. In one embodiment, the Mw and Mw / Mn of the cellulose raw material may each be within the above range. In both Mw control and Mw / Mn control, examples of the physical treatment include dry or wet grinding using a microfluidizer, ball mill, or disk mill, and physical treatments that apply mechanical forces such as impact, shear, shear, or friction using a crusher, homomixer, high-pressure homogenizer, or ultrasonic device. Examples of the chemical treatment include cooking, bleaching, acid treatment, enzyme treatment, conversion to regenerated cellulose, and hydrolysis. The Mw, Mn, and Mw / Mn of chemically modified cellulose fine fibers may not be accurately calculated due to the presence of chemically modifying groups. In this case, the Mw, Mn, and Mw / Mn of the cellulose fine fibers immediately before chemical modification, which are the raw material for the chemically modified cellulose fine fibers, or the cellulose raw material immediately before chemical modification, may be considered to be the Mw, Mn, and Mw / Mn of the chemically modified cellulose fine fibers.

[0089] In the present disclosure, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the cellulose raw material or cellulose fine fibers are values ​​determined by dissolving the cellulose raw material or cellulose fine fibers in N,N-dimethylacetamide containing added lithium chloride, and then performing gel permeation chromatography using N,N-dimethylacetamide as a solvent.

[0090] [Average content of alkali-soluble polysaccharides] Alkali-soluble polysaccharides such as hemicellulose and acid-insoluble components such as lignin are present between the microfibrils and between the microfibril bundles of cellulose raw materials or cellulose fine fibers. Hemicellulose is a polysaccharide composed of sugars such as mannan and xylan, and plays a role in connecting the microfibrils by hydrogen bonding with cellulose. Lignin is a compound with an aromatic ring, and is known to be covalently bonded to hemicellulose in plant cell walls.

[0091] Alkali-soluble polysaccharides that may be contained in cellulose raw materials or cellulose fine fibers include hemicellulose, β-cellulose, and γ-cellulose. Alkali-soluble polysaccharides are understood by those skilled in the art as components obtained as the alkali-soluble portion of holocellulose obtained by solvent extraction and chlorine treatment of plants (e.g., wood) (i.e., components remaining after excluding α-cellulose from holocellulose).

[0092] In one embodiment, the average alkali-soluble polysaccharide content of the cellulose raw material or cellulose fine fibers is preferably 20% by mass or less, or 18% by mass or less, or 15% by mass or less, or 12% by mass or less, based on 100% by mass of the cellulose raw material or cellulose fine fibers, from the viewpoint of maintaining the mechanical strength of the cellulose fine fibers during melt-kneading and suppressing yellowing. From the viewpoint of easy availability of the cellulose raw material, the content may be 0.1% by mass or more, or 0.5% by mass or more, or 1% by mass or more, or 2% by mass or more, or 3% by mass or more.

[0093] The average alkali-soluble polysaccharide content can be determined by the method described in a non-patent document (Wood Science Experiment Manual, edited by the Japan Wood Research Society, pp. 92-97, 2000), by subtracting the α-cellulose content from the holocellulose content (Wise method). This method is understood in the art as a method for measuring hemicellulose content. The alkali-soluble polysaccharide content is calculated three times for each sample, and the number average of the calculated alkali-soluble polysaccharide contents is taken as the average alkali-soluble polysaccharide content.

[0094] [Average Content of Acid-Insoluble Components] The acid-insoluble components that may be contained in cellulose raw materials or cellulose fine fibers are understood by those skilled in the art as insoluble components remaining after a defatted sample obtained by solvent extraction of a plant (e.g., wood) is treated with sulfuric acid. The acid-insoluble components are specifically, but not limited to, aromatic-derived lignin.

[0095] In one embodiment, the average content of acid-insoluble components in the cellulose raw material or cellulose fine fibers is preferably 10% by mass or less, 5% by mass or less, or 3% by mass or less, based on 100% by mass of the cellulose raw material or cellulose fine fibers, from the viewpoint of avoiding a decrease in heat resistance of the cellulose fine fibers and the resulting discoloration. From the viewpoint of easy availability of the cellulose raw material, the content may be 0.1% by mass or more, 0.2% by mass or more, or 0.3% by mass or more.

[0096] The average acid-insoluble component content is determined by the Clason method described in the non-patent literature (Wood Science Experiment Manual, edited by the Japan Wood Research Society, pp. 92-97, 2000). This method is understood in the art as a method for measuring lignin content. The sample is stirred in a sulfuric acid solution to dissolve cellulose, hemicellulose, etc., and then filtered through glass fiber filter paper. The resulting residue corresponds to the acid-insoluble component. The acid-insoluble component content is calculated from the weight of this acid-insoluble component, and the number average of the acid-insoluble component contents calculated for three samples is taken as the average acid-insoluble component content.

[0097] [Thermal decomposition start temperature (T D ) )] The thermal decomposition starting temperature (T D ) is preferably 220°C or higher, or 230°C or higher, or 240°C or higher, or 250°C or higher, or 260°C or higher, or 270°C or higher, or 275°C or higher, or 280°C or higher, or 285°C or higher, from the viewpoint of avoiding thermal degradation during melt-kneading and shaping, suppressing foaming, and exhibiting good mechanical strength. The higher the thermal decomposition onset temperature, the more preferable. However, from the viewpoint of ease of production of cellulose fine fibers, it may be, for example, 320°C or lower, 310°C or lower, or 300°C or lower.

[0098] [Temperature at 1% weight loss (T 1% ), 250℃ weight loss rate (T 250℃ ) )] The temperature at which the cellulose raw material or cellulose fine fibers lose 1 wt % of their weight (T 1%In one aspect, from the viewpoint of avoiding thermal degradation during melt-kneading and being able to exhibit mechanical strength, the temperature is preferably 230°C or higher, or 240°C or higher, or 250°C or higher, or 260°C or higher, or 270°C or higher, or 275°C or higher, or 280°C or higher, or 285°C or higher, or 290°C or higher. 1% The higher the temperature, the better, but from the viewpoint of ease of production of cellulose fine fibers, it may be, for example, 330°C or less, 320°C or less, or 310°C or less.

[0099] The weight loss rate at 250°C of the cellulose raw material or cellulose fine fibers (T 250℃ From the viewpoint of avoiding thermal degradation during melt-kneading and being able to exhibit mechanical strength, in one aspect, T is preferably 15% or less, or 12% or less, or 10% or less, or 8% or less, or 6% or less, or 5% or less, or 4% or less, or 3% or less. 250℃ The lower the better, but from the viewpoint of ease of production of cellulose fine fibers, it may be, for example, 0.1% or more, 0.5% or more, 0.7% or more, or 1.0% or more.

[0100] In this disclosure, T D is a value obtained from a graph in which the horizontal axis is temperature and the vertical axis is weight retention % in thermogravimetric (TG) analysis under nitrogen flow. The porous sheet of the present disclosure is heated from room temperature to 150°C at a heating rate of 10°C / min in a nitrogen flow of 100 ml / min, and after being held at 150°C for 1 hour, the temperature is then raised to 450°C at a heating rate of 10°C / min. Starting from the weight (weight loss of 0 wt%) at 150°C (state where moisture is almost completely removed), the temperature at which 1 wt% weight loss occurs (T 1% ) and the temperature at which the weight loss reaches 2 wt% (T 2% The temperature at the point where this line intersects with the horizontal line (baseline) that passes through the starting point of the weight loss of 0 wt% is called T D It is defined as:

[0101] 1% weight loss temperature (T 1% ) is the above T D The temperature is the temperature at which the weight loss reaches 1% by weight, starting from the weight at 150°C, when the temperature is continued to be increased by the method of (1).

[0102] The weight loss rate at 250°C of the cellulose raw material or cellulose fine fibers (T 250℃ ) is the weight loss rate when a sample is held at 250°C under nitrogen flow for 2 hours in TG analysis. The sample is heated from room temperature to 150°C at a temperature increase rate of 10°C / min in a nitrogen flow of 100 ml / min, held at 150°C for 1 hour, then heated from 150°C to 250°C at a temperature increase rate of 10°C / min, and held at 250°C for 2 hours. Starting with the weight W0 at the time when 250°C is reached, and the weight after holding at 250°C for 2 hours as W1, the weight change rate at 250°C (%) is calculated using the following formula: (W0 - W1) / W0 x 100

[0103] In addition, the crystalline polymorphism, crystallinity, degree of polymerization, Mw, Mn, Mw / Mn, average alkali-soluble polysaccharide content, average acid-insoluble component content, T D , T 1% , T 250℃ In measuring DS, DSs, DS heterogeneity ratio, and DS heterogeneity ratio, it is preferable to use a distortion-free porous sheet as the measurement sample in order to reduce fluctuations in values ​​due to the shape of the measurement sample and perform stable and reproducible measurements. The porous sheet is prepared as follows.

[0104] First, a concentrated cake of a sample with a solid content of 10% by mass or more is added to tert-butanol, and further dispersion treatment is carried out using a mixer or the like until no aggregates remain. The concentration is adjusted to 0.5% by mass for 0.5 g of sample solids. 100 g of the obtained tert-butanol dispersion is filtered on filter paper. Without peeling the filtered material from the filter paper, it is sandwiched together with the filter paper between two larger pieces of filter paper, and dried in an oven at 150°C for 5 minutes while pressing down the edges of the larger filter paper with weights. The filter paper is then peeled off to obtain a porous sheet with little distortion. When the air resistance R of this sheet is 10 g / m2, the sheet weight is 10 g / m2. 2 The porous sheet having a permeability of 100 sec / 100 ml or less is used as a measurement sample. The method for measuring the air permeability resistance R is as follows. The basis weight W (g / m) of a porous sheet sample left to stand for one day in an environment of 23°C and 50% RH is measured. 2After measuring the air resistance R (sec / 100 ml), an Oken-type air resistance tester (for example, manufactured by Asahi Seiko Co., Ltd., Model EG01) is used to measure the air resistance R (sec / 100 ml). 2 Calculate the value per unit area. Unit area 10 g / m 2 Air resistance per unit area (sec / 100 ml) = R / W x 10

[0105] [Defibrillation of Cellulose Raw Material] Cellulose fine fibers can be obtained by defibrillating a cellulose raw material. In one embodiment, the cellulose fine fibers are mechanically defibrillated. In one embodiment, mechanical defibrillation may be a beating treatment. Defibration may be performed on a cellulose raw material that has or has not undergone the pretreatment of this embodiment, but is preferably performed on a cellulose raw material that has undergone pretreatment. The beating treatment may be performed by dispersing the cellulose raw material in an aqueous medium and subjecting the resulting dispersion to the following treatment. Examples of aqueous media include water itself, or a mixture of water and one or more organic solvents selected from the group consisting of monohydric alcohols such as ethanol, n-propanol, isopropanol, and butanol, polyhydric alcohols such as ethylene glycol, diethylene glycol, and glycerin, ketones such as acetone, nitrile-based solvents such as acetonitrile, and pyrrolidone-based solvents. The blending ratio of the organic solvent in the mixture of the organic solvent and water is preferably less than 50% by mass, more preferably 30% by mass or less, and particularly preferably 20% by mass or less. The higher the water ratio, the better the defibration performance, and the higher the organic solvent ratio, the more effectively the aggregation of fine fibers is suppressed during the drying process after defibration. Therefore, it is preferable to set the ratio of organic solvent in consideration of the balance between defibration performance and aggregation suppression. Beating is distinguished from pulverization as a pretreatment of this embodiment in that it is a wet process, and from grinding as a pretreatment of this embodiment in that the fiber length of the cellulose subjected to the treatment is different.

[0106] In the beating treatment, a cellulose raw material (for example, a pulp sheet) is dispersed in an aqueous medium using a pulper or homomixer, if necessary, and then refined using a beating device such as a beater, disc refiner, high-pressure homogenizer, water jet, disc mill, ball mill, bead mill, mass colloider, homomixer, etc. The beating treatment may be carried out in one stage or in multiple stages, and when carried out in multiple stages, the same device may be used multiple times, or different devices may be used in combination.

[0107] Furthermore, prior to the beating treatment, it is preferable to homogeneously disperse the cellulose raw material in an aqueous medium using the above-mentioned pulper or homomixer. In particular, when the cellulose raw material is first chemically modified and then beaten, the hydrophilicity of the cellulose raw material is reduced. Therefore, it is preferable to perform the dispersion treatment using a mixer such as a homomixer at a peripheral speed of 10 m / s or more, preferably 20 m / s or more, more preferably 25 m / s or more, and 90 m / s or less, preferably 80 m / s or less, more preferably 50 m / s or less, in one embodiment. By reducing agglomerates during the dispersion treatment, homogeneous cellulose fine fibers can be obtained by a homogeneous beating treatment. Note that highly pure water such as distilled water or ion-exchanged water can be effectively used as the water in the aqueous medium used in this case.

[0108] (Multi-stage beating) When beating cellulose in multiple stages, it is effective to combine two or more types of beating devices with different refining mechanisms or shear rates. Here, as a method of multi-stage beating, it is preferable to perform multi-stage beating using disc refiners with different disc configurations, or to perform beating in a disc refiner followed by beating in a high-pressure homogenizer. As the disc refiner, any of a single disc refiner, a double disc refiner, and a conical refiner may be used, but in order to highly control beating, a single disc refiner is preferred because it has high accuracy of clearance control between the fixed blade and the rotary blade.

[0109] (Beating with a Disc Refiner) Beating is particularly preferably carried out using a disc refiner. When using a disc refiner, pulp or cotton-like cellulose raw material is dispersed and stored in a tank so as to have an appropriate solids concentration in an aqueous medium, and then beaten using the disc refiner. The lower limit of the solids concentration can be adjusted to preferably 0.5% by mass or more, more preferably 0.8% by mass or more, and even more preferably 1.0% by mass or more. The upper limit of the concentration is preferably 6% by mass or less, more preferably 3.5% by mass or less, and particularly preferably 3% by mass or less. As the water used in this case, highly pure water such as distilled water or ion-exchanged water may be effective.

[0110] When operating a disc refiner, defibration processing can be performed using a continuous circulation process in which the slurry stored in a tank is returned to the original tank via the disc refiner. However, it is preferable to prepare two tanks (referred to as Tank A and Tank B) connected by piping via a disc refiner, and first transfer the slurry from Tank A to Tank B via the disc refiner and store it there. When processing of the slurry in Tank A is completed, the process is switched to continuously transfer the slurry from Tank B to Tank A via the disc refiner and store it there. Thereafter, if defibration processing is performed using a continuous processing process in which these steps are repeated alternately, the slurry will reliably pass through the disc refiner every time it is processed, and a uniform number of passes can be performed on the entire amount of slurry, which is more preferable from the viewpoint of uniformity of the degree of defibration, i.e., the quality stability of cellulose fine fibers.

[0111] When beating is performed using a disc refiner, it may be performed in multiple stages (treatment with multiple types of blades) or in one stage (treatment with one type of blade).

[0112] Fig. 1 is a diagram illustrating an example of the arrangement of blades and grooves of a disc refiner, and Fig. 2 is a diagram illustrating the blade width, groove width, and blade distance of a disc refiner. When multiple disc refiners are used for multi-stage beating, it is preferable to use refiners with at least two different types of blades. With reference to Figs. 1 and 2, a specific blade configuration is as follows: in a disc refiner having blades 11 and grooves 12 as shown in Fig. 1, the blade width W B , groove width W G , and cutting width W B groove width W G The value obtained by dividing the fiber length by the groove ratio (hereinafter referred to as the flute ratio) is important, and it is particularly preferable to perform a beating process (hereinafter referred to as the front stage) using a refiner equipped with blades having a blade width of 1.5 mm or more and a flute ratio of 0.1 to 1.0 (hereinafter referred to as the front stage), and then perform a beating process (hereinafter referred to as the back stage) using a refiner equipped with blades having a blade width of 0.1 mm or more and a flute ratio of 0.5 to 1.0 (hereinafter referred to as the back stage). Defibrating using a disc refiner with such a configuration reduces the number of long fibers that cause aggregation in the resin, and also allows the production of cellulose fibers with a low fibrillation rate (i.e., low fluff). In this case, a separate beating step may be added between the front and back stages.

[0113] Furthermore, when performing disc refiner processing in one stage using one type of blade, it is particularly preferable to perform the beating process using a refiner having a blade with a blade width of 0.1 mm or more and 1.0 mm or less and a blade groove ratio of 0.5 or more and 1.0 or less.

[0114] (Blade Distance in Disc Refiner Treatment) Referring to FIG. 2, in the beating process using a disc refiner, the blade distance W between two blades (specifically, the rotary blade 21 and the fixed blade 22 in FIG. 2) is LIt is advantageous to control the clearance (hereinafter simply referred to as the blade distance). By controlling the blade distance, it is possible to control the fiber length and degree of beating of the cellulose fine fibers. When processing in multiple stages, it is preferable to set the blade distance to 0.05 mm or more and 0.5 mm or less in the first stage of processing, and to set the blade distance to 0.05 mm or more and 0.3 mm or less in the second stage of processing. Furthermore, when processing in one stage, it is preferable to set the blade distance to 0.05 mm or more and 0.3 mm or less. When adjusting the blade distance, it is preferable to start with a wider blade distance and gradually narrow the blade distance while keeping the current value of the device below a certain level. By controlling in this manner, clogging and overloading of the device can be prevented, and highly homogeneous cellulose fine fibers can be obtained.

[0115] Thus, highly controlling the blade distance between the fixed blade and the rotary blade during cellulose beating using a disc refiner is advantageous for producing homogeneous cellulose fine fibers with good mechanical properties suitable for filler. For example, the blade distance adjustment of conventional single-disc refiners is typically performed using a screw-type jack, which results in play in the runner section that secures the rotary blade. Therefore, if the runner section is pulled strongly in the thrust direction, it will move by approximately 0.3 mm. Therefore, a small amount of this movement (play) is preferable for obtaining beaten cellulose with high precision and good reproducibility. The movement amount is preferably 0.1 mm or less, more preferably 0.08 mm or less, and even more preferably 0.05 mm or less. In one embodiment, a single-disc refiner with the above-mentioned thrust direction movement amount of 0.03 mm can be used by using a ball screw jack as the blade distance adjustment mechanism. Furthermore, in order to adjust the blade distance with high precision, it is preferable to attach a reducer to the ball screw jack to enable fine adjustment of the blade distance. The use of such a single-disc refiner enables fine adjustment of the blade distance and enables beating while maintaining a constant blade distance without blade vibration during the beating process. This prevents the blades from coming into contact with each other when the blade distance is reduced, thereby preventing the fiber length from becoming too short and reducing coarse fibers. As a result, it becomes possible to reproducibly produce cellulose fine fibers with a highly uniform shape distribution that imparts excellent mechanical properties to the resin composition obtained by compounding the cellulose fine fibers with a resin.

[0116] (Number of passes in disc refiner treatment) The beating process can also be controlled by the number of times the cellulose fibers pass between the rotary blade and the fixed blade (hereinafter referred to as the number of passes). By increasing the number of passes, cellulose fibers with a uniform fiber diameter and fiber length distribution can be obtained. Here, the number of passes means the number of times the refining treatment is performed (i.e., the number of times the fibers pass between the rotary blade and the fixed blade) after the blade distance is reduced to the desired blade distance.

[0117] The number of passes through the disc refiner is preferably 5 or more, more preferably 20 or more, and even more preferably 40 or more. As the number of passes increases, the distribution of fiber shapes gradually converges to a constant value, so a higher number is preferable, but considering productivity, the upper limit of the number of passes is preferably 300 or less.

[0118] (Method for Determining Beating Conditions Using a Disc Refiner) The shape of cellulose fine fibers obtained by disc refiner processing is controlled by the combined effects of the aforementioned disc refiner blade type, blade distance, number of passes, concentration, and the like. To obtain a shape of cellulose fine fibers suitable for use in fiber-reinforced resins, it is preferable to increase the number of passes under viscous beating conditions. Viscous beating is a beating method that tends to fluff and refine fibers, while a beating method that tends to cause cutting in the fiber length direction is called free beating. The greater the number of blades, the longer the blade length, the greater the ratio of blade width to groove width (blade groove ratio), and the greater the contact angle, the greater the number of intersections between the rotating blade and the fixed blade. This disperses the force applied to the fibers at each intersection, increasing the number of impacts on the fibers and resulting in a tendency toward viscous beating. On the other hand, when the above conditions are reversed, a tendency toward free beating is demonstrated. The blade distance of the disc refiner is preferably widened when blades that exhibit a tendency toward free beating are used, and is preferably narrowed when blades that exhibit a tendency toward free beating are used, but a blade distance that is too narrow can lead to clogging, fiber shortening due to fiber length cutting, and excessive fineness, so the blade distance is preferably 0.05 mm or more. By adjusting the blade distance and the number of passes described above depending on the shape of the cellulose raw material (fiber length and fiber diameter), the treatment concentration, and the blades used, it is possible to control the fiber shape, such as the average fiber diameter and fiber length distribution, within a preferred range.

[0119] (Multistage beating treatment using a combination of a disc refiner and a high-pressure homogenizer) One preferred embodiment is to further subject the cellulose fibers beaten with a disc refiner to a beating treatment using a high-pressure homogenizer. A high-pressure homogenizer has a greater effect of thinning fibers than a disc refiner. The high-pressure homogenizer treatment is preferably carried out at a pressure of 30 MPa or more, more preferably 50 MPa or more, and more preferably 80 MPa or more. The upper limit of the pressure may be preferably 300 MPa or less, more preferably 250 MPa or less, and even more preferably 150 MPa or less, depending on the characteristics of the apparatus.

[0120] Examples of high-pressure homogenizers include the NS-type high-pressure homogenizer from Niro Soavi (Italy), the Lanier-type (R model) pressure homogenizer from SMT Co., Ltd., and the high-pressure homogenizer from Sanwa Machine Co., Ltd., and examples of ultra-high-pressure homogenizers include high-pressure collision type beating machines such as the Microfluidizer from Mizuho Kogyo Co., Ltd., the Nanomizer from Yoshida Kikai Kogyo Co., Ltd., and the Ultimizer from Sugino Machine Co., Ltd., but other devices may also be used as long as they perform micronization using a mechanism similar to that of these devices.

[0121] In the high-pressure homogenizer treatment, as in the disc refiner treatment, the defibration treatment may be carried out in a continuous circulating treatment process in which the slurry stored in a tank is returned to the original tank via the high-pressure homogenizer. However, it is preferable to prepare two tanks (referred to as Tank A and Tank B) connected by piping via a high-pressure homogenizer, and first transfer the slurry from Tank A to Tank B via the high-pressure homogenizer and store it therein. When the treatment of the slurry in Tank A is completed, the process is switched to continuously transfer the slurry from Tank B to Tank A via the high-pressure homogenizer and store it therein. Thereafter, if the defibration treatment is carried out in a continuous treatment process in which these steps are repeated alternately, the slurry will reliably pass through the high-pressure homogenizer every time it is treated, and a uniform number of passes can be performed on the entire amount of slurry, which is more preferable from the viewpoint of the uniformity of the degree of defibration, i.e., the quality stability of the cellulose fine fibers.

[0122] [Shape of Cellulose Fine Fibers] (Average Fiber Length) The cellulose fine fibers of this embodiment preferably have a longer average fiber length because the mechanical properties are better when the fine fibers are used as a reinforcing material for resins, etc. That is, when the fiber length is long, the fibers become entangled when blended into the resin, allowing the cellulose fine fibers to be uniformly dispersed in the resin without forming aggregates. This improves the stress transmission of the resin composition, resulting in increased strength and fracture strain. The average fiber length, as measured by an automatic fiber shape analyzer, is preferably 400 μm or more, more preferably 500 μm or more, even more preferably 600 μm or more, and particularly preferably 700 μm or more. The length-weighted average fiber length is defined in ISO / FDIS 16065-2:2006, and is the average value of the fiber length corresponding to the actual fiber length taking into account the bent shape of bent fibers. The longer the fiber length, the greater the above-mentioned effects, so there is no particular upper limit. However, in one embodiment, it is 3 mm or less, and a preferred range is 1000 μm or less.

[0123] (Average fiber diameter) In one aspect, the average fiber diameter of the cellulose fine fibers of this embodiment, as measured with an automatic fiber shape analyzer, is 1,000 nm or less, and preferably 500 nm or less, or 300 nm or less, or 200 nm or less, or 150 nm or less, or 130 nm or less. When the average fiber diameter is within the above range, it is easy to sufficiently increase the L / D of each cellulose fiber. When the L / D is large, the cellulose fine fibers become entangled with each other in the resin, thereby increasing the strength of the resin composition. Since a smaller average fiber diameter is preferable because it allows for a larger L / D, there is no particular lower limit. However, since a certain thickness is desired to increase the bending elasticity of the resin composition, the average fiber diameter is preferably 10 nm or more, or 20 nm or more, or 30 nm or more, or 40 nm or more.

[0124] (Coefficient of Variation (CV) of Average Fiber Length) In the cellulose fine fibers of this embodiment, when the variation in the fiber length is small, the anisotropy of mechanical properties (tensile strength, flexural strength, tensile modulus, flexural modulus, thermal expansion coefficient, etc.) is small, which is preferable among the reinforcing effects when added to a resin. The variation in fiber length is expressed as the coefficient of variation CV by the following formula: CV (%) = (standard deviation of fiber length (µm) / average fiber length (µm)) x 100 CV is preferably 20% or less, more preferably 15% or less, and particularly preferably 12% or less. The lower this value, the greater the effect described above, so there is no particular lower limit, but realistically, 1% or more is preferable.

[0125] (Wet cake, dried body) The cellulose fine fibers of this embodiment can be obtained in the form of a wet molded body (wet cake) by dehydrating the slurry using a filter, a paper machine, or the like. Among these, a papermaking method using a paper machine is advantageous in that it reduces drying shrinkage of the cellulose fine fibers. In one aspect, dehydration is performed by filtering the slurry on a porous substrate. In the papermaking method, any papermaking machine can be used that is equipped with wires of a mesh size that dehydrates the slurry and retains the cellulose fine fibers. As the papermaking apparatus, when a flat sheet-shaped composite molded body is to be obtained, an apparatus such as an inclined wire papermaking machine, a Fourdrinier papermaking machine, or a cylinder papermaking machine can be used.

[0126] When cellulose fine fibers are used as a dry filler, they can be dried using a known drying device such as a hot air dryer or a spray dryer. Because cellulose tends to aggregate during the drying process and is difficult to redisperse afterwards, it is preferable to use a dispersant. By increasing the redispersibility, the mechanical properties and stability of the resulting resin composition can be improved. It is desirable to add a dispersant to a cellulose aqueous dispersion, and then dry it under shear to obtain a cellulose powder.

[0127] The dispersant can be at least one selected from the group consisting of surfactants, organic compounds with a boiling point of 100° C. or higher, and resins having a chemical structure capable of highly dispersing cellulose.

[0128] The surfactant may have a chemical structure in which a moiety having a hydrophilic substituent and a moiety having a hydrophobic substituent are covalently bonded. As the surfactant, surfactants used for various purposes such as food and industrial use can be used, and for example, the following surfactants can be used alone or in combination of two or more:

[0129] Any of anionic surfactants, nonionic surfactants, amphoteric surfactants, and cationic surfactants can be used as the surfactant. However, in terms of affinity with cellulose, anionic surfactants and nonionic surfactants are preferred, and nonionic surfactants are more preferred.

[0130] Among the above, surfactants having a polyoxyethylene chain, a carboxyl group, or a hydroxyl group as a hydrophilic group are preferred in terms of affinity with cellulose, polyoxyethylene surfactants (polyoxyethylene derivatives) having a polyoxyethylene chain as a hydrophilic group are more preferred, and nonionic polyoxyethylene derivatives are even more preferred. The polyoxyethylene chain length of the polyoxyethylene derivative is preferably 3 or more, more preferably 5 or more, even more preferably 10 or more, and particularly preferably 15 or more. The longer the chain length, the higher the affinity with cellulose, but in terms of the balance with coatability, the upper limit is preferably 60 or less, more preferably 50 or less, even more preferably 40 or less, particularly preferably 30 or less, and most preferably 20 or less.

[0131] Among the surfactants described above, alkyl ether, alkylphenyl ether, rosin ester, bisphenol A, β-naphthyl, styrenated phenyl, and hydrogenated castor oil hydrophobic groups are particularly suitable due to their high affinity with resins. The preferred alkyl chain length (in the case of alkylphenyl, the number of carbon atoms excluding the phenyl group) is preferably 5 or more, more preferably 10 or more, even more preferably 12 or more, and particularly preferably 16 or more. The higher the number of carbon atoms in the alkyl chain, the higher the affinity with typical resins, so there is no upper limit, but the upper limit for the number of carbon atoms is preferably 30 or less, and more preferably 25 or less.

[0132] Among these hydrophobic groups, those having a cyclic structure or those having a bulky and multifunctional structure are preferred. As those having a cyclic structure, alkylphenyl ether type, rosin ester type, bisphenol A type, β-naphthyl type, and styrenated phenyl type are preferred, and as those having a multifunctional structure, hydrogenated castor oil type is preferred. Among these, rosin ester type and hydrogenated castor oil type are particularly more preferred.

[0133] Furthermore, organic compounds with a boiling point of 100°C or higher may be effective as non-surfactant dispersants. Examples of such organic compounds include polyethylene glycol, polypropylene glycol, and organic compounds having a glycerin structure. Furthermore, depending on the type of resin, for example, if the resin is a polyolefin, high-boiling organic solvents such as liquid paraffin and decalin are effective. Furthermore, if the resin is a polar resin such as nylon or polyacetate, it may be effective to use a solvent similar to the aprotic solvent that can be used in producing cellulose microfibers, such as dimethyl sulfoxide.

[0134] In the resin composition, the amount of cellulose fine fibers per 100 parts by mass of thermoplastic resin is preferably 1 part by mass or more, or 3 parts by mass or more, or 5 parts by mass or more, or 10 parts by mass or more, from the viewpoint of obtaining a good effect of improving the physical properties of the resin composition by the cellulose fine fibers, and is preferably 150 parts by mass or less, or 100 parts by mass or less, or 80 parts by mass or less, from the viewpoint of avoiding performance degradation due to disruption of the continuous layer of the thermoplastic resin and molding defects due to reduced fluidity of the resin composition during molding.

[0135] Also, from the above viewpoint, the content of cellulose fine fibers in the resin composition may be, in one embodiment, 1% by mass or more, or 3% by mass or more, or 5% by mass or more, or 10% by mass or more, and in one embodiment, 30% by mass or less, or 25% by mass or less, or 20% by mass or less.

[0136] <Thermoplastic Resin> The thermoplastic resin may be, for example, a crystalline resin having a melting point in the range of 100°C to 350°C, an amorphous resin having a glass transition temperature in the range of 100°C to 250°C, a thermoplastic elastomer, or the like. In this disclosure, the melting point refers to the peak-top temperature of the endothermic peak that appears when the temperature is increased from 23°C at a heating rate of 10°C / min using a differential scanning calorimeter (DSC). If two or more endothermic peaks appear, it refers to the peak-top temperature of the endothermic peak with the highest temperature. The enthalpy of this endothermic peak is preferably 10 J / g or more, more preferably 20 J / g or more. Furthermore, during measurement, it is desirable to first heat the sample to a temperature condition of the melting point + 20°C or higher to melt the resin, and then cool it to 23°C at a heating rate of 10°C / min. In the present disclosure, the glass transition temperature refers to the peak-top temperature at which the storage modulus significantly decreases and the loss modulus reaches its maximum when measured using a dynamic viscoelasticity measuring device at a heating rate of 2°C / min from 23°C and an applied frequency of 10 Hz. When two or more loss modulus peaks appear, the glass transition temperature refers to the peak-top temperature of the highest peak. In order to improve measurement accuracy, the measurement frequency is preferably at least once every 30 seconds. There are no particular restrictions on the method for preparing the measurement sample, but from the viewpoint of eliminating the influence of molding distortion, it is desirable to use a cut-out piece of a heat-press molded product, and from the viewpoint of thermal conduction, it is desirable for the size (width and thickness) of the cut-out piece to be as small as possible.

[0137] Examples of crystalline resins include polyolefin resins, polyamide resins, polyester resins, polyacetal resins, polyphenylene sulfide resins, polyether ether ketone resins, polyimide resins, liquid crystal polymers, and polytetrafluoroethylene resins. Examples include mixtures of two or more of these. From the viewpoints of ease of handling and cost, preferred are polyolefin resins, polyamide resins, polyester resins, and polyacetal resins, with polyamide resins, polyolefin resins, and polyacetal resins being more preferred. Furthermore, from the viewpoint of the toughness of the resin composition, polyamide resins are particularly preferred. From the viewpoint of enhancing the heat resistance of the resin composition, the melting point of the crystalline resin is preferably 140° C. or higher, or 150° C. or higher, or 160° C. or higher, or 170° C. or higher, or 180° C. or higher, or 190° C. or higher, or 200° C. or higher, or 210° C. or higher, or 220° C. or higher, or 230° C. or higher, or 240° C. or higher, or 245° C. or higher, or 250° C. or higher. In one embodiment, the melting point may be 300° C. or lower.

[0138] Examples of amorphous resins include amorphous polyolefin resins such as polymethylene pentene and cyclic polyolefin, amorphous polyvinyl resins such as polystyrene and polyvinyl chloride, polycarbonate resins, acrylic resins, methacrylic resins, polyvinyl alcohol resins, polysulfone resins, polyphenylene ether resins, polyethersulfone resins, acrylonitrile-styrene resins, acrylonitrile-butadiene-styrene resins, polyketone resins, polyetherimide resins, and polyamideimide resins.

[0139] From the viewpoint of improving the heat resistance of the molded object, the molding temperature (temperature of the discharge port) when an amorphous resin is used is preferably 130°C or higher, 140°C or higher, 150°C or higher, 160°C or higher, 170°C or higher, 180°C or higher, 190°C or higher, 200°C or higher, 210°C or higher, 220°C or higher, 230°C or higher, 240°C or higher, 245°C or higher, or 250°C or higher.

[0140] In a preferred embodiment, the thermoplastic resin includes a crystalline resin. In a preferred embodiment, the thermoplastic resin includes a crystalline resin having a melting point of 150°C to 300°C. In a preferred embodiment, the thermoplastic resin includes a polyamide-based resin. In a preferred embodiment, the thermoplastic resin includes one or more resins selected from the group consisting of polyamide-based resins and polyacetal-based resins, or is one or more resins selected from the group consisting of polyamide-based resins and polyacetal-based resins.

[0141] [Polyolefin Resin] Polyolefin resins preferred as thermoplastic resins are polymers obtained by polymerizing olefins (e.g., α-olefins) and / or alkenes as monomer units. Specific examples of polyolefin resins include ethylene (co)polymers exemplified by low-density polyethylene (e.g., linear low-density polyethylene), high-density polyethylene, ultra-low-density polyethylene, and ultra-high-molecular-weight polyethylene; polypropylene (co)polymers exemplified by polypropylene, ethylene-propylene copolymer, and ethylene-propylene-diene copolymer; and copolymers of ethylene and α-olefins exemplified by ethylene-acrylic acid copolymer, ethylene-methyl methacrylate copolymer, and ethylene-glycidyl methacrylate copolymer.

[0142] The most preferred polyolefin resin here is polypropylene. In particular, polypropylene having a melt mass flow rate (MFR) of 3 g / 10 min or more and 50 g / 10 min or less, measured at 230 ° C. under a load of 21.2 N in accordance with ISO 1133, is preferred. The lower limit of the MFR is more preferably 5 g / 10 min, 6 g / 10 min, or 8 g / 10 min. The upper limit is more preferably 40 g / 10 min, 30 g / 10 min, 25 g / 10 min, 20 g / 10 min, or 18 g / 10 min. It is desirable that the MFR not exceed the upper limit from the viewpoint of improving the toughness of the resin composition, and not be below the lower limit from the viewpoint of the fluidity of the resin composition.

[0143] In addition, acid-modified polyolefin resins can also be suitably used to enhance affinity with cellulose fine fibers. Examples of acids used for acid modification include mono- or polycarboxylic acids, such as maleic acid, fumaric acid, succinic acid, phthalic acid, and their anhydrides, as well as citric acid. Maleic acid or its anhydride is particularly preferred because it is easy to increase the modification rate. While there are no particular limitations on the modification method, a common method involves heating a polyolefin resin above its melting point in the presence or absence of a peroxide and melt-kneading it. While all of the polyolefin resins listed above can be used as the acid-modified polyolefin resin, polypropylene is particularly suitable. While acid-modified polypropylene resins may be used alone, it is more preferable to use them in combination with unmodified polypropylene resins to adjust the modification rate of the resin as a whole. In this case, the ratio of the acid-modified polypropylene resin to all polypropylene resins is preferably 0.5% by mass to 50% by mass. A more preferred lower limit is 1 mass%, 2 mass%, 3 mass%, 4 mass%, or 5 mass%. A more preferred upper limit is 45 mass%, 40 mass%, 35 mass%, 30 mass%, or 20 mass%. In order to maintain the interfacial strength between the resin and the cellulose fine fibers, a content equal to or greater than the lower limit is preferred, and in order to maintain the ductility of the resin, a content equal to or less than the upper limit is preferred.

[0144] The melt mass-flow rate (MFR) of the acid-modified polypropylene resin, measured in accordance with ISO 1133 at 230°C under a load of 21.2 N, is preferably 50 g / 10 min or more, 100 g / 10 min or more, 150 g / 10 min or more, or 200 g / 10 min or more, from the viewpoint of enhancing the affinity at the interface between the resin and the cellulose fine fibers. The upper limit is not particularly limited, but is preferably 500 g / 10 min, from the viewpoint of maintaining mechanical strength.

[0145] [Polyamide Resin] Preferred polyamide resins as the thermoplastic resin include polyamides obtained by polycondensation of lactams (e.g., polyamide 6, polyamide 11, polyamide 12, etc.); diamines (e.g., 1,6-hexanediamine, 2-methyl-1,5-pentanediamine, 1,7-heptanediamine, 2-methyl-1-6-hexanediamine, 1,8-octanediamine, 2-methyl-1,7-heptanediamine, 1,9-nonanediamine, 2-methyl-1,8-octanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, m-xylylenediamine, etc.) and dicarboxylic acids (e.g., butanedioic acid, pentanedioic acid, hexanedioic acid, etc.); , heptanedioic acid, octanedioic acid, nonanedioic acid, decanedioic acid, benzene-1,2-dicarboxylic acid, benzene-1,3-dicarboxylic acid, benzene-1,4-dicarboxylic acid, cyclohexane-1,3-dicarboxylic acid, cyclohexane-1,4-dicarboxylic acid, etc.) (for example, polyamide 6,6, polyamide 6,10, polyamide 6,11, polyamide 6,12, polyamide 6,T, polyamide 6,I, polyamide 9,T, polyamide 10,T, polyamide 2M5,T, polyamide MXD,6, polyamide 6,C, polyamide 2M5,C, etc.); and copolymers in which these are copolymerized, respectively (for example, polyamide 6,T / 6,I, etc.).

[0146] Among these polyamide resins, aliphatic polyamides such as polyamide 6, polyamide 11, polyamide 12, polyamide 6,6, polyamide 6,10, polyamide 6,11, and polyamide 6,12, and alicyclic polyamides such as polyamide 6,C and polyamide 2M5,C are more preferred.

[0147] From the viewpoint of improving the heat resistance of the resin composition, the melting point of the polyamide resin is preferably 190°C or higher, or 200°C or higher, or 210°C or higher, or 220°C or higher, or 230°C or higher, or 240°C or higher, or 245°C or higher, or 250°C or higher, and from the viewpoint of ease of production of the resin composition, the melting point is preferably 350°C or lower, or 320°C or lower, or 300°C or lower.

[0148] The terminal carboxyl group concentration of the polyamide resin is not particularly limited, but is preferably 20 μmol / g or more, or 30 μmol / g or more, and preferably 150 μmol / g or less, or 100 μmol / g or less, or 80 μmol / g or less.

[0149] In the polyamide resin, the ratio of carboxyl terminal groups to all terminal groups ([COOH] / [total terminal groups]) is preferably 0.30 or more, or 0.35 or more, or 0.40 or more, or 0.45 or more, from the viewpoint of dispersibility of cellulose fine fibers in the resin composition, and is preferably 0.95 or less, or 0.90 or less, or 0.85 or less, or 0.80 or less, from the viewpoint of the color tone of the resin composition.

[0150] The terminal amino group concentration of the polyamide resin is not particularly limited, but the lower limit is preferably 20 μmol / g, 30 μmol / g, or 50 μmol / g, and the upper limit is preferably 150 μmol / g or 100 μmol / g.

[0151] The amino terminal group ratio ([NH2] / ([NH2]+[COOH])) of the polyamide resin is preferably 0.20 or more, or 0.30 or more, or 0.35 or more from the viewpoint of dispersibility of cellulose in the resin composition, and is preferably 0.95 or less, or 0.90 or less, or 0.85 or less, or 0.80 or less from the viewpoint of the color tone of the resulting resin composition.

[0152] In one embodiment, the resin composition may include a first thermoplastic resin having an amino end group ratio of 65 mmol / g or more, or 75 mmol / g or more, or 85 mmol / g or more, and 200 mmol / g or less, or 150 mmol / g or less, or 120 mmol / g or less, and a second thermoplastic resin having an amino end group ratio of 5 mmol / g or more, or 10 mmol / g or more, or 15 mmol / g or more, and 60 mmol / g or less, or 50 mmol / g or less, or 40 mmol / g or less.

[0153] The terminal group concentration of the polyamide resin can be adjusted by a known method, such as adding a terminal modifier (e.g., a diamine compound, a monoamine compound, a dicarboxylic acid compound, a monocarboxylic acid compound, an acid anhydride, a monoisocyanate, a monoacid halide, a monoester, a monoalcohol, etc.) that reacts with the terminal groups to the polymerization solution during polyamide polymerization so as to achieve a predetermined terminal group concentration.

[0154] Examples of terminal modifiers that react with terminal amino groups include aliphatic monocarboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, and isobutyric acid; alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid; aromatic monocarboxylic acids such as benzoic acid, toluic acid, α-naphthalenecarboxylic acid, β-naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, and phenylacetic acid; and mixtures of any of these. Among these, from the standpoints of reactivity, stability of the blocked terminals, cost, and the like, one or more terminal modifiers selected from the group consisting of acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, and benzoic acid are preferred, with acetic acid being most preferred.

[0155] Examples of terminal modifiers that react with terminal carboxyl groups include aliphatic monoamines such as methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine, stearylamine, dimethylamine, diethylamine, dipropylamine, and dibutylamine; alicyclic monoamines such as cyclohexylamine and dicyclohexylamine; aromatic monoamines such as aniline, toluidine, diphenylamine, and naphthylamine, and any mixtures thereof. Among these, one or more terminal modifiers selected from the group consisting of butylamine, hexylamine, octylamine, decylamine, stearylamine, cyclohexylamine, and aniline are preferred in terms of reactivity, boiling point, stability of the blocked terminals, cost, etc.

[0156] The concentrations of amino end groups and carboxyl end groups of the polyamide resin are 1The H-NMR can be used to determine the end group concentration from the integrated value of the characteristic signal corresponding to each end group. This method is preferred in terms of accuracy and simplicity. More specifically, it is recommended to use the method described in JP-A-7-228775, using deuterated trifluoroacetic acid as the measurement solvent, and setting the number of integration scans to 300 or more.

[0157] The intrinsic viscosity [η] of a polyamide resin measured in concentrated sulfuric acid at 30°C is preferably 0.6 to 2.0 dL / g, or 0.7 to 1.4 dL / g, or 0.7 to 1.2 dL / g, or 0.7 to 1.0 dL / g, from the viewpoint of achieving good in-mold fluidity and good appearance of molded pieces when the resin composition is, for example, injection molded. In the present disclosure, "intrinsic viscosity" is synonymous with the viscosity generally referred to as intrinsic viscosity. The intrinsic viscosity is determined by measuring the ηsp / c of ​​several measurement solvents of different concentrations in 96% concentrated sulfuric acid at 30°C, deriving a relationship between each of the ηsp / c and the concentration (c), and extrapolating the concentration to zero. This value extrapolated to zero is the intrinsic viscosity. Details of the above method are described, for example, in Polymer Process Engineering (Prentice-Hall, Inc. 1994), pages 291 to 294. From the viewpoint of accuracy, it is desirable to set the concentrations in the measurement solvents having different concentrations to at least four points (e.g., 0.05 g / dL, 0.1 g / dL, 0.2 g / dL, and 0.4 g / dL).

[0158] The number average molecular weight of the polyamide resin is preferably 3,000 or more, or 5,000 or more, or 8,000 or more from the viewpoint of moldability, and is preferably 30,000 or less, or 20,000 or less, or 13,000 or less from the viewpoint of flowability. The number average molecular weight is a value determined using gel permeation chromatography in terms of standard polymethyl methacrylate.

[0159] [Polyester-based resin] Preferred polyester-based resins as the thermoplastic resin include one or more selected from polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polybutylene adipate terephthalate (PBAT), polyhydroxyalkanoic acid (PHA), polylactic acid (PLA), polyarylate (PAR), etc. Among these, PET, PBS, PBSA, PBT, and PEN are more preferred, and PBS, PBSA, and PBT are particularly preferred.

[0160] The terminal groups of the polyester resin can be changed as desired by adjusting the monomer ratio during polymerization, the presence or absence of addition of a terminal stabilizer and the amount thereof, etc. The ratio of carboxyl terminal groups to all terminal groups of the polyester resin ([COOH] / [total terminal groups]) is preferably 0.30 or more, or 0.35 or more, or 0.40 or more, or 0.45 or more from the viewpoint of dispersibility of cellulose fine fibers in the resin composition, and is preferably 0.95 or less, or 0.90 or less, or 0.85 or less, or 0.80 or less from the viewpoint of the color tone of the resin composition.

[0161] [Polyacetal Resin] Preferred polyacetal resins as thermoplastic resins are generally homopolyacetals made from formaldehyde and copolyacetals containing trioxane as the main monomer and 1,3-dioxolane as a comonomer component. Both can be used, but copolyacetals are preferred from the viewpoint of thermal stability during processing. The amount of the structure derived from the comonomer component (e.g., 1,3-dioxolane) is preferably 0.01 mol% or more, or 0.05 mol% or more, or 0.1 mol% or more, or 0.2 mol% or more from the viewpoint of thermal stability during extrusion and molding, and is preferably 4.0 mol% or less, or 3.5 mol% or less, or 3.0 mol% or less, or 2.5 mol% or less, or 2.3 mol% or less from the viewpoint of mechanical strength.

[0162] [Thermoplastic Elastomer] In one embodiment, an elastomer in the present disclosure is a substance (specifically, a natural or synthetic polymer substance) that is elastic at room temperature (23°C). Furthermore, being elastic in one embodiment means that the storage modulus at 23°C and 10 Hz measured by dynamic viscoelasticity measurement is 1 MPa or more and 100 MPa or less. The thermoplastic elastomer may be a conjugated diene polymer or a non-conjugated diene polymer, and in one embodiment, is a crosslinked product.

[0163] (Conjugated Diene Polymer) The conjugated diene polymer may be a homopolymer, a copolymer of two or more conjugated diene monomers, or a copolymer of a conjugated diene monomer and another monomer. The copolymer may be either random or block.

[0164] Examples of the conjugated diene monomer include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 3-methyl-1,3-pentadiene, 1,3-heptadiene, and 1,3-hexadiene, and these may be used alone or in combination of two or more.

[0165] In one embodiment, the conjugated diene polymer is a copolymer of the above-mentioned conjugated diene monomer and an aromatic vinyl monomer. The aromatic vinyl monomer is not particularly limited as long as it is a monomer copolymerizable with the conjugated diene monomer, and examples thereof include styrene, m- or p-methylstyrene, α-methylstyrene, ethylstyrene, p-tert-butylstyrene, vinylethylbenzene, vinylxylene, vinylnaphthalene, diphenylethylene, and divinylbenzene, and these may be used alone or in combination of two or more. From the viewpoints of the moldability of the resin composition and the impact resistance of the molded article, styrene-based monomers, particularly styrene, are preferred.

[0166] Examples of random copolymers include butadiene-isoprene random copolymers, butadiene-styrene random copolymers, isoprene-styrene random copolymers, and butadiene-isoprene-styrene random copolymers. The composition distribution of each monomer in the copolymer chain includes a completely random copolymer that is close to a statistically random composition, and a tapered (gradient) random copolymer with a gradient in composition distribution. The bonding mode of the conjugated diene polymer, i.e., the composition of 1,4-bonds, 1,2-bonds, etc., may be uniform or different between molecules.

[0167] The block copolymer may be a copolymer consisting of two or more blocks. For example, the block copolymer may have a structure such as A-B, A-B-A, or A-B-A-B, in which a block A of an aromatic vinyl monomer and a block B of a conjugated diene monomer and / or a copolymer of an aromatic vinyl monomer and a conjugated diene monomer constitute a block copolymer. The boundaries between the blocks do not necessarily need to be clearly distinguished. For example, when block B is a copolymer of an aromatic vinyl monomer and a conjugated diene monomer, the aromatic vinyl monomer in block B may be distributed uniformly or in a tapered manner. Furthermore, block B may have a plurality of portions where the aromatic vinyl monomer is distributed uniformly and / or a plurality of portions where the aromatic vinyl monomer is distributed in a tapered manner. Furthermore, block B may have a plurality of segments with different aromatic vinyl monomer contents. When a copolymer contains a plurality of blocks A and a plurality of blocks B, the molecular weights and compositions of the blocks A and B may be the same or different.

[0168] The block copolymer may be a mixture of two or more types that differ from each other in one or more of the bonding type, molecular weight, aromatic vinyl compound type, conjugated diene compound type, 1,2-vinyl content or the total amount of 1,2-vinyl content and 3,4-vinyl content, aromatic vinyl compound component content, hydrogenation rate, etc.

[0169] Examples of the hydrogenated conjugated diene polymer include the hydrogenated conjugated diene polymers exemplified above, and may be, for example, hydrogenated products of butadiene homopolymer, isoprene homopolymer, styrene-butadiene copolymer, and acrylonitrile-butadiene copolymer.

[0170] [Non-conjugated diene polymer] The non-conjugated diene polymer may be a homopolymer, or a copolymer of two or more types of non-conjugated diene monomers, or a copolymer of a non-conjugated diene monomer and another monomer. The copolymer may be either random or block. Examples of the non-conjugated diene polymer include olefin polymers such as ethylene-propylene rubber, ethylene-propylene-diene rubber, ethylene-butene-diene rubber, and ethylene-α-olefin copolymer, butyl rubber, brominated butyl rubber, acrylic rubber, fluororubber, silicone rubber, chlorinated polyethylene rubber, epichlorohydrin rubber, α,β-unsaturated nitrile-acrylate-conjugated diene copolymer rubber, urethane rubber, and polysulfide rubber.

[0171] In the ethylene-α-olefin copolymer, examples of monomers that can be copolymerized with ethylene units include aliphatic substituted vinyl monomers such as propylene, butene-1, pentene-1, 4-methylpentene-1, hexene-1, heptene-1, octene-1, nonene-1, decene-1, undecene-1, dodecene-1, tridecene-1, tetradecene-1, pentadecene-1, hexadecene-1, heptadecene-1, octadecene-1, nonadecene-1, or eicosene-1, and isobutylene, and styrene. aromatic vinyl monomers such as vinyl acetate, acrylic acid esters, methacrylic acid esters, glycidyl acrylic acid esters, glycidyl methacrylic acid esters, and hydroxyethyl methacrylic acid esters; nitrogen-containing vinyl monomers such as acrylamide, allylamine, vinyl-p-aminobenzene, and acrylonitrile; and dienes such as butadiene, cyclopentadiene, 1,4-hexadiene, and isoprene.

[0172] The ethylene-α-olefin copolymer is preferably a copolymer of ethylene and one or more α-olefins having 3 to 20 carbon atoms, more preferably a copolymer of ethylene and one or more α-olefins having 3 to 16 carbon atoms, and most preferably a copolymer of ethylene and one or more α-olefins having 3 to 12 carbon atoms.

[0173] From the viewpoint of impact resistance, the molecular weight of the ethylene-α-olefin copolymer is preferably 10,000 or more, more preferably 10,000 to 100,000, more preferably 10,000 to 80,000, and even more preferably 20,000 to 60,000, as a number average molecular weight (Mn) measured using a gel permeation chromatography measuring device with 1,2,4-trichlorobenzene as a solvent at 140°C and polystyrene standards.

[0174] The ethylene unit content of the ethylene-α-olefin copolymer is preferably 30 to 95% by mass based on the total amount of the ethylene-α-olefin copolymer, from the viewpoint of ease of handling during processing.

[0175] Ethylene-α-olefin copolymers can be produced by conventionally known production methods such as those described in, for example, JP-B-4-12283, JP-A-60-35006, JP-A-60-35007, JP-A-60-35008, JP-A-5-155930, JP-A-3-163088, and U.S. Pat. No. 5,272,236.

[0176] The number average molecular weight (Mn) of the thermoplastic elastomer is preferably 10,000 to 500,000, or 40,000 to 250,000, from the viewpoint of achieving both impact strength and fluidity.

[0177] The thermoplastic elastomer may have a core-shell structure. Examples of elastomers having a core-shell structure include core-shell elastomers having a core made of particulate rubber and a shell made of a glassy graft layer formed on the outside of the core. Suitable core materials include butadiene rubber, acrylic rubber, and silicone-acrylic composite rubber. Suitable shell materials include glassy polymers such as styrene resin, acrylonitrile-styrene copolymer, and acrylic resin.

[0178] As the thermoplastic elastomer, a styrene-based elastomer is preferred from the viewpoint of obtaining a molded article having excellent toughness. For example, it may be particularly advantageous in terms of toughness if the thermoplastic resin contains a polyamide-based resin and a styrene-based elastomer.

[0179] The styrene-based elastomer is preferably at least one selected from the group consisting of styrene-butadiene block copolymers, styrene-ethylene-butadiene block copolymers, styrene-ethylene-butylene block copolymers, styrene-butadiene-butylene block copolymers, styrene-isoprene block copolymers, styrene-ethylene-propylene block copolymers, styrene-isobutylene block copolymers, hydrogenated products of styrene-butadiene block copolymers, hydrogenated products of styrene-ethylene-butadiene block copolymers, hydrogenated products of styrene-butadiene-butylene block copolymers, hydrogenated products of styrene-isoprene block copolymers, and styrene homopolymers (polystyrene), and more preferably at least one selected from the group consisting of styrene-butadiene block copolymers, hydrogenated products of styrene-butadiene block copolymers, and polystyrene.

[0180] In one embodiment, at least a portion of the thermoplastic elastomer may have an acidic functional group. In this disclosure, the term "thermoplastic elastomer having an acidic functional group" means that the acidic functional group is attached to the molecular backbone of the elastomer via a chemical bond. In this disclosure, the term "acidic functional group" refers to a functional group that can react with a basic functional group, and specific examples include a hydroxyl group, a carboxyl group, a carboxylate group, a sulfo group, and an acid anhydride group.

[0181] From the viewpoint of affinity between the cellulose fine fibers and the elastomer component, the amount of acidic functional groups added in the elastomer is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.2% by mass or more, and preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 2% by mass or less, based on 100% by mass of the elastomer. The number of acidic functional groups is a value obtained by measuring a calibration curve sample, which has been mixed in advance with an acidic substance, using an infrared absorption spectrometer and measuring the sample based on a calibration curve that has been prepared using the characteristic absorption band of the acid.

[0182] Examples of the elastomer having an acidic functional group include an elastomer having a core-shell structure having a shell layer formed using acrylic acid or the like as a copolymerization component, and a modified elastomer obtained by grafting an α,β-unsaturated dicarboxylic acid or a derivative thereof onto an ethylene-α-olefin copolymer, polyolefin, aromatic compound-conjugated diene copolymer, or hydrogenated aromatic compound-conjugated diene copolymer containing acrylic acid or the like as a monomer, in the presence or absence of a peroxide.

[0183] In a preferred embodiment, the elastomer is an anhydride-modified elastomer.

[0184] Among these, modified products obtained by grafting an α,β-unsaturated dicarboxylic acid or a derivative thereof onto a polyolefin, an aromatic compound-conjugated diene copolymer, or a hydrogenated aromatic compound-conjugated diene copolymer in the presence or absence of a peroxide are more preferred, and among these, modified products obtained by grafting an α,β-unsaturated dicarboxylic acid or a derivative thereof onto an ethylene-α-olefin copolymer or a hydrogenated aromatic compound-conjugated diene block copolymer in the presence or absence of a peroxide are particularly preferred.

[0185] Specific examples of the α,β-unsaturated dicarboxylic acid and its derivatives include maleic acid, fumaric acid, maleic anhydride, and fumaric anhydride, with maleic anhydride being particularly preferred.

[0186] In one embodiment, the elastomer may be a mixture of an elastomer having an acidic functional group and an elastomer not having an acidic functional group. The mixing ratio of the elastomer having an acidic functional group and the elastomer not having an acidic functional group, when the total of both is 100% by mass, is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, and most preferably 40% by mass or more, from the viewpoint of maintaining high toughness and stable physical properties of the resin composition. The upper limit is not particularly limited, and substantially all of the elastomer may be an elastomer having an acidic functional group. However, from the viewpoint of avoiding problems with flowability, it is desirable for the upper limit to be 80% by mass or less.

[0187] The content of the thermoplastic resin in the resin composition is preferably 20% by mass or more, or 30% by mass or more, and preferably 99% by mass or less, or 95% by mass or less, or 90% by mass or less.

[0188] <Elastomer Additives> The resin composition may contain various conventionally known elastomer additives (stabilizers, softeners, antioxidants, etc.). Examples of the elastomer stabilizer include one or more antioxidants such as 2,6-di-tert-butyl-4-hydroxytoluene (BHT), n-octadecyl-3-(4'-hydroxy-3',5'-di-tert-butylphenyl)propionate, 2-methyl-4,6-bis[(octylthio)methyl]phenol, and pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate). Examples of the elastomer softener include one or more process oils, extender oils, etc. However, in one aspect, the resin composition of this embodiment is capable of forming a flexible molded article, and therefore, in one aspect, does not contain an elastomer softener.

[0189] <Dispersant> In one embodiment, the resin composition contains a dispersant. The dispersant contributes to improving the dispersibility of cellulose fine fibers in the thermoplastic resin. The dispersant may be a single substance or a mixture of two or more substances. In the latter case, the characteristic values ​​in the present disclosure refer to the values ​​of the mixture.

[0190] [Amphiphilic Molecule] In one embodiment, it is more preferable that the dispersant has a hydrophilic segment and a hydrophobic segment in the same molecule (i.e., is an amphiphilic molecule) from the viewpoint of dispersing the cellulose fine fibers more uniformly in the resin.

[0191] The hydrophilic segment is a portion that exhibits good affinity with cellulose fine fibers due to its hydrophilic structure. Examples of the hydrophilic structure include hydroxyl groups, thiol groups, carboxyl groups, sulfonic acid groups, sulfate ester groups, phosphate groups, boronic acid groups, silanol groups, groups derived from sugars such as sorbitan and sucrose, groups derived from glycerin, groups represented by -OM, -COOM, -SO3M, -OSO3M, -HMPO4, and -M2PO4 (where M represents an alkali metal or alkaline earth metal), as well as primary, secondary, and tertiary amines and quaternary ammonium salts. Examples of counter anions of the quaternary ammonium salts include one or more hydrophilic groups selected from the group consisting of hydroxide ions; halide ions such as fluoride ions, chloride ions, bromide ions, and iodide ions; and nitrate ions, formate ions, acetate ions, trifluoroacetate ions, p-toluenesulfonate ions, hexafluorophosphate, and tetrafluoroborate.

[0192] Examples of hydrophilic segments include polyethylene glycol segments, segments containing repeating units having a quaternary ammonium salt structure, polyvinyl alcohol segments, polyvinylpyrrolidone segments, polyacrylic acid segments, carboxyvinyl polymer segments, cationized guar gum segments, hydroxyethyl cellulose segments, methyl cellulose segments, carboxymethyl cellulose segments, and polyurethane soft segments (specifically, diol segments). Nonionic polyoxyethylene derivatives are particularly preferred, and the polyoxyethylene chain length of the polyoxyethylene derivative may be 3 or more, 5 or more, 10 or more, or 15 or more. The longer the chain length, the higher the affinity with cellulose fine fibers. However, from the viewpoint of a balance with the desired properties (e.g., mechanical properties) of the resin molded article, the polyoxyethylene chain length may be 60 or less, 50 or less, 40 or less, 30 or less, or 20 or less.

[0193] Examples of hydrophobic segments include segments containing hydrocarbons, segments containing alkylene oxide units having 3 or more carbon atoms (for example, PPG blocks), and segments containing polymer structures.

[0194] Preferred hydrocarbon-containing segments are alkyl, alkenyl, alkyl ether, alkenyl ether, alkyl phenyl ether, alkenyl phenyl ether, rosin ester, bisphenol A, β-naphthyl, styrenated phenyl, and hydrogenated castor oil. The number of carbon atoms in the alkyl or alkenyl chain of the hydrophobic group (in the case of alkylphenyl or alkenylphenyl, the number of carbon atoms excluding the phenyl group) is preferably 5 or more, or 10 or more, or 12 or more, or 16 or more.

[0195] Examples of the segment containing a polymer structure include acrylic polymers, styrene resins, vinyl chloride resins, vinylidene chloride resins, polyolefin resins, polyhexamethylene adipamide (6,6 nylon), polyhexamethylene azelamide (6,9 nylon), polyhexamethylene sebacamide (6,10 nylon), polyhexamethylene dodecanoamide (6,12 nylon), polybis(4-aminocyclohexyl)methanedodecane, and other polycondensates of organic dicarboxylic acids having 4 to 12 carbon atoms and organic diamines having 2 to 13 carbon atoms, and polycondensates of ω-amino acids (for example, ω-aminoundecanoic acid) (for example, polyundecane). Preferred examples of the resin include amino acid lactams containing ring-opening polymerization products of lactams, such as polycapramide (nylon 6) which is a ring-opening polymerization product of ε-aminocaprolactam, and polylauric lactam (nylon 12) which is a ring-opening polymerization product of ε-aminolaurolactam; polymers composed of diamines and dicarboxylic acids; polyacetal resins, polycarbonate resins, polyester resins, polyphenylene sulfide resins, polysulfone resins, polyether ketone resins, polyimide resins, fluorine-based resins, hydrophobic silicone resins, melamine resins, epoxy resins, and phenolic resins.

[0196] In one embodiment, any of anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants can be used as the amphiphilic molecules. The dispersant may be a polymeric surfactant, a reactive surfactant, or the like. In terms of affinity with cellulose fine fibers, cationic surfactants and nonionic surfactants are preferred, and in terms of heat resistance, nonionic surfactants are more preferred.

[0197] The structure of the amphiphilic molecule is not particularly limited, but when the hydrophilic segment is A and the hydrophobic segment is B, examples include AB block copolymers, ABA block copolymers, BAB block copolymers, ABAB block copolymers, ABABA block copolymers, BABAB block copolymers, tri-branched copolymers containing A and B, tetra-branched copolymers containing A and B, star copolymers containing A and B, monocyclic copolymers containing A and B, polycyclic copolymers containing A and B, and cage copolymers containing A and B.

[0198] The structure of the dispersant is preferably an AB block copolymer, an ABA triblock copolymer, a tri-branched copolymer containing A and B, or a tetra-branched copolymer containing A and B, and more preferably an ABA triblock copolymer, a tri-branched structure (i.e., a tri-branched copolymer containing A and B), or a tetra-branched structure (i.e., a tetra-branched copolymer containing A and B). In order to ensure good affinity with cellulose fine fibers, the structure of the dispersant is desirably the above structure.

[0199] [Hydrophilic Polymer] In one embodiment, the dispersant is preferably a hydrophilic polymer. Examples of hydrophilic polymers that can be used include cellulose derivatives (hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, etc.), polyalkylene glycols, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, carboxyvinyl polymers, cationized guar gum, water-soluble polyurethanes, polymers containing a quaternary ammonium salt structure, amides, amines, and the like. Among these, cellulose derivatives and polyalkylene glycols are more preferred. Because cellulose derivatives are cellulose-based substances, they have high affinity with cellulose, while also being thermoplastic resins, they are preferred for their high effect of improving the dispersion stability of cellulose in resin compositions. Polyalkylene glycols can be obtained by adding alkylene oxides having 2 to 4 carbon atoms, and polyethylene glycols having 2 carbon atoms are preferred in terms of affinity with cellulose. In terms of increasing high-temperature rigidity, the number of repeating oxyalkylene units is preferably 3 or more, or 5 or more, or 10 or more, or 15 or more, or 20 or more, or 30 or more, or 40 or more, or 50 or more, or 60 or more, or 70 or more, or 80 or more, or 90 or more, or 100 or more, and in terms of processability, it is preferably 1000 or less, or 900 or less, or 800 or less, or 700 or less, or 600 or less, or 550 or less, or 500 or less.

[0200] [Liquid Polymer] In one embodiment, the dispersant is preferably a liquid polymer. Specific examples of the liquid polymer include liquid rubber, liquid polyolefin, liquid acrylic polymer, and liquid paraffin.

[0201] (Liquid Rubber) Liquid rubber refers to a substance that has fluidity at 23°C and forms a rubber elastomer by crosslinking (more specifically, vulcanization) and / or chain extension. That is, in one embodiment, liquid rubber is an uncured product. Furthermore, having fluidity means, in one embodiment, that when liquid rubber dissolved in cyclohexane is placed in a vial having a body diameter of 21 mm and a total length of 50 mm at 23°C and then dried, the liquid rubber is filled into the vial to a height of 1 mm, sealed, and the vial is left standing upside down for 24 hours, and a movement of the substance in the vertical direction of 0.1 mm or more can be confirmed.

[0202] The liquid rubber may have a monomer composition of a typical rubber, and preferably has a relatively low molecular weight from the viewpoints of ease of handling and good dispersibility of cellulose microfibers. In one aspect, the liquid rubber is in a liquid form when its number average molecular weight (Mn) is 80,000 or less. The number average molecular weight and weight average molecular weight of the various rubbers disclosed herein are values ​​determined in terms of standard polystyrene using gel permeation chromatography with chloroform as a solvent at a measurement temperature of 40°C, unless otherwise specified.

[0203] In one embodiment, liquid rubber may be combined with cellulose microfibers to form a masterbatch, and such masterbatch may be combined with a resin to form the resin composition of the present disclosure.

[0204] The number average molecular weight (Mn) of the liquid rubber is preferably 1,000 or more, or 1,500 or more, or 2,000 or more from the viewpoint of thermal stability and the effect of improving the dispersibility of cellulose fine fibers in the resin, and is preferably 80,000 or less, or 50,000 or less, or 40,000 or less, or 30,000 or less, or 10,000 or less from the viewpoint of having high fluidity suitable for good dispersion when dispersing cellulose fine fibers in the liquid rubber.

[0205] The weight average molecular weight (Mw) of the liquid rubber is preferably 1,000 or more, or 2,000 or more, or 4,000 or more from the viewpoint of thermal stability and the effect of improving the dispersibility of cellulose fine fibers in the resin, and is preferably 240,000 or less, or 150,000 or less, or 30,000 or less from the viewpoint of having high fluidity suitable for good dispersion when dispersing cellulose fine fibers in the liquid rubber.

[0206] The ratio (Mw / Mn) of the number average molecular weight (Mn) to the weight average molecular weight (Mw) of the liquid rubber is preferably 1.5 or more, or 1.8 or more, or 2 or more, in that a certain degree of variation in molecular weight makes it possible to achieve a high degree of compatibility between multiple properties (in one embodiment, a high degree of compatibility between good dispersion of cellulose fine fibers in the resin and good flexural modulus of the resin composition), and is preferably 10 or less, or 8 or less, or 5 or less, or 3 or less, or 2.7 or less, in that the variation in molecular weight is not excessively large and the desired physical properties of the resin composition can be stably obtained, for example, in that a balance between fluidity and impact resistance can be achieved.

[0207] The liquid rubber can have good thermal stability. D In view of good thermal stability, in one embodiment, the thermal decomposition starting temperature is 200° C. or higher, or 250° C. or higher, or 300° C. or higher. Although a higher thermal decomposition starting temperature is preferable, in view of easy availability of the liquid rubber, in one embodiment, the thermal decomposition starting temperature may be 500° C. or lower, or 450° C. or lower, or 400° C. or lower.

[0208] The glass transition temperature of the liquid rubber is preferably −150° C. or higher, or −120° C. or higher, or −100° C. or higher in terms of good thermal stability, and is preferably 25° C. or lower, or 10° C. or lower, or 0° C. or lower in terms of good fluidity.

[0209] In one embodiment, the liquid rubber includes a diene rubber, and in another embodiment, the liquid rubber includes a conjugated diene polymer, a non-conjugated diene polymer, or a hydrogenated product thereof. Suitable examples of the conjugated diene polymer and the non-conjugated diene polymer may be the same as those exemplified above as thermoplastic elastomers. The above polymers or hydrogenated products thereof may be oligomers. The monomers constituting the liquid rubber may be unmodified or modified (e.g., acid-modified, hydroxyl-modified, etc.). In one embodiment, the liquid rubber may have reactive groups (e.g., one or more selected from the group consisting of hydroxyl groups, carboxy groups, isocyanato groups, thio groups, amino groups, and halo groups) at both ends and therefore may be bifunctional. These reactive groups contribute to crosslinking and / or chain extension of the liquid rubber.

[0210] In one embodiment, the liquid rubber comprises at least one selected from the group consisting of diene rubber, silicone rubber, urethane rubber, polysulfide rubber, and hydrogenated products thereof.

[0211] The viscosity of the liquid rubber at 25°C is preferably 1,000,000 mPa·s or less, or 500,000 mPa·s or less, or 200,000 mPa·s or less, from the viewpoint of good dispersion of the cellulose fine fibers in the liquid rubber, and is preferably 100 mPa·s or more, or 300 mPa·s or more, or 500 mPa·s or more, from the viewpoints of thermal stability, the effect of improving the dispersibility of the cellulose fine fibers in the resin, and the mechanical properties of the resin composition.

[0212] The viscosity of the liquid rubber at 80°C is preferably 1,000,000 mPa·s or less, or 500,000 mPa·s or less, or 250,000 mPa·s or less, or 100,000 mPa·s or less, from the viewpoint of dispersing the cellulose fine fibers well in the liquid rubber and dispersing the cellulose fine fibers well in the resin by heat kneading, and is preferably 50 mPa·s or more, or 100 mPa·s or more, or 300 mPa·s or more, from the viewpoints of thermal stability, the effect of improving the dispersibility of the cellulose fine fibers in the resin, and the mechanical properties of the resin composition.

[0213] The viscosity of the liquid rubber at 0°C is preferably 2,000,000 mPa·s or less, or 1,000,000 mPa·s or less, or 400,000 mPa·s or less, from the viewpoint of good dispersion of the cellulose fine fibers in the liquid rubber, and is preferably 200 mPa·s or more, or 600 mPa·s or more, or 1,000 mPa·s or more, from the viewpoint of thermal stability, the effect of improving the dispersibility of the cellulose fine fibers in the resin, and the mechanical properties of the resin composition.

[0214] The liquid rubber having a low temperature dependency of viscosity is preferred in that the cellulose fine fibers can be well dispersed in the liquid rubber over a wide range of mixing temperatures. From this viewpoint, it is particularly preferred that the viscosity of the liquid rubber at all of 80°C, 25°C and 0°C be within the above range.

[0215] The viscosity of the liquid rubber is a value measured using a Brookfield viscometer at a rotation speed of 10 rpm.

[0216] The amount of dispersant in the resin composition is preferably 0.3% by mass or more, or 0.5% by mass or more, or 1.0% by mass or more, from the viewpoint of dispersing the cellulose fine fibers well in the thermoplastic resin, and is preferably 20.0% by mass or less, or 15.0% by mass or less, or 10.0% by mass or less, or 5.0% by mass or less, or 3.0% by mass or less, from the viewpoint of avoiding the dispersant acting as a plasticizer for the thermoplastic resin due to its presence in a large amount.

[0217] The amount of dispersant in a resin composition can be easily confirmed by methods common to those skilled in the art. The confirmation method is not limited, but the following method can be exemplified. Using broken fragments of a resin composition, the broken fragments are dissolved in a solvent that dissolves the resin, and then soluble fraction 1 (resin and dispersant) and insoluble fraction 1 (cellulose microfibers and dispersant) are separated. Soluble fraction 1 is reprecipitated in a solvent that does not dissolve the resin but dissolves the dispersant, and then separated into insoluble fraction 2 (resin) and soluble fraction 2 (dispersant). Furthermore, insoluble fraction 1 is dissolved in a dispersant-soluble solvent, and then separated into soluble fraction 3 (dispersant) and insoluble fraction 3 (cellulose microfibers). The dispersant can be quantified by concentrating soluble fractions 2 and 3 (drying, air drying, vacuum drying, etc.). The concentrated dispersant can be identified and its molecular weight measured using the method described above.

[0218] <Additional Components> The resin composition may further contain additional components as necessary to improve its performance. Examples of additional components include filler components other than cellulose; compatibilizers; plasticizers; polysaccharides such as starches and alginic acid; natural proteins such as gelatin, glue, and casein; inorganic compounds such as zeolite, ceramics, talc, silica, metal oxides, and metal powders; colorants; fragrances; pigments; flow control agents; leveling agents; conductive agents; antioxidants; antistatic agents; UV absorbers; UV dispersants; and deodorizers. The content of any additional components in the resin composition is appropriately selected within a range that does not impair the desired effects of the present invention, and may be, for example, 0.01 to 50% by mass or 0.1 to 30% by mass.

[0219] <<Method for producing resin composition>> In one embodiment, the resin composition can be obtained by mixing cellulose fine fibers and a thermoplastic resin, for example, by melt-kneading. Examples of mixing methods include: - a method in which a resin monomer and cellulose fine fibers are mixed, a polymerization reaction is carried out, the resulting resin composition is extruded into a strand, and cooled and solidified in a water bath to obtain a pellet-shaped molded product; - a method in which a mixture of a resin and cellulose fine fibers is melt-kneaded using a single-screw or twin-screw extruder, extruded into a strand, and cooled and solidified in a water bath to obtain a pellet-shaped molded product; - a method in which a mixture of a resin and cellulose fine fibers is melt-kneaded using a single-screw or twin-screw extruder, extruded into a rod or cylindrical shape, and cooled to obtain an extrusion molded product; - a method in which a mixture of a resin and cellulose fine fibers is melt-kneaded using a single-screw or twin-screw extruder, and extruded through a T-die to obtain a sheet- or film-shaped molded product. In a preferred embodiment, a mixture of a resin and cellulose fine fibers is melt-kneaded using a single-screw or twin-screw extruder, extruded into strands, and cooled and solidified in a water bath to obtain pellet-shaped molded products. For example, cellulose fine fibers transported to a desired ratio with respect to the resin are introduced into the resin, mixed, and then melt-kneaded.

[0220] For melt kneading, an extruder such as a single-screw extruder or a twin-screw extruder can be used, but a twin-screw extruder is preferred in terms of controlling the dispersibility of the cellulose fine fibers. The ratio L / D, obtained by dividing the cylinder length (L) of the extruder by the screw diameter (D), is preferably 30 or more, and particularly preferably 40 or more. The screw rotation speed during kneading is preferably in the range of 50 to 800 rpm, and more preferably in the range of 100 to 600 rpm.

[0221] Each screw in the cylinder of the extruder is optimized by combining a conveying screw with an elliptical two-wing screw shape, a kneading element called a kneading disk, and the like.

[0222] The minimum processing temperatures recommended by thermoplastic resin suppliers are 255 to 270°C for polyamide 66, 225 to 240°C for polyamide 6, 225 to 240°C for polybutylene terephthalate, 170 to 190°C for polyacetal resin, and 160 to 180°C for polypropylene. The heating setting temperature is preferably in a range 20°C higher than these recommended minimum processing temperatures. By setting the mixing temperature within this temperature range, the cellulose fine fibers and resin can be mixed uniformly.

[0223] In one embodiment, the resin composition may contain recycled material from a shaped object or other molded article. In one embodiment, the content of recycled material in the resin composition may be 5% by weight or more, or 10% by weight or more, or 15% by weight or more, and in one embodiment, 100% by weight or less, or 95% by weight or less, or 90% by weight or less, or 85% by weight or less.

[0224] <<Shape of Resin Composition>> The resin composition of this embodiment can be provided in various shapes. Specific examples include resin pellets, sheets, fibers, plates, rods, etc., with the resin pellet shape being preferred due to ease of post-processing and transportation. Preferred resin pellet shapes include round, elliptical, and cylindrical shapes, and the shape may vary depending on the cutting method used during extrusion. For example, pellets cut using a cutting method known as underwater cutting are often round, pellets cut using a cutting method known as hot cutting are often round or elliptical, and pellets cut using a cutting method known as strand cutting are often cylindrical. The preferred pellet diameter for round pellets is 1 mm or more and 3 mm or less. The preferred diameter for cylindrical pellets is 1 mm or more and 3 mm or less, and the preferred length is 2 mm or more and 10 mm or less. The above diameter and length are preferably set to be equal to or greater than the lower limit from the viewpoint of operational stability during extrusion, and are preferably set to be equal to or less than the upper limit from the viewpoint of fitment into a molding machine during post-processing.

[0225] <3D Printing Modeling Material and Its Manufacturing Method> The 3D printing modeling material composed of the resin composition of this embodiment may be in the form of a filament, pellet, powder, or the like, and is typically a filament. The filament may be a monofilament or a multifilament, but a monofilament is preferred due to ease of molding. The diameter of the filament-shaped modeling material is preferably 0.5 to 5.0 mm, more preferably 1.0 to 3.5 mm, and most preferably 1.5 to 3.0 mm. The length of the filament-shaped modeling material is preferably greater than 1 m, more preferably greater than 10 m, more preferably greater than 100 m, and most preferably greater than 300 m. Controlling the shape of the filament-shaped modeling material within this range allows for a wide selection of applicable 3D printers and allows for appropriate design of the modeling time, size, and precision of the modeled object. In one embodiment, the length of the filament-shaped modeling material may be 20,000 m or less.

[0226] In one embodiment, the filament-shaped shaping material can be produced by heating and melting the resin composition, passing it through a fine hole such as a nozzle, cooling it, and winding it up. The diameter of the fine hole can be selected appropriately depending on the diameter of the filament and the winding speed. From the viewpoints of production efficiency and the frequency of thread breakage, it is preferably 0.5 to 10.0 mm, more preferably 0.8 to 5.0 mm, and most preferably 1.0 to 3.0 mm. The cooling method can be selected from known methods such as air cooling and water cooling. However, air cooling is preferred from the viewpoint of preventing water absorption due to the hydrophilicity of the cellulose microfibers. From the viewpoints of production efficiency and the frequency of thread breakage, the winding speed of the filament is preferably 0.1 to 10 m / s, more preferably 0.15 to 5 m / s, and most preferably 0.2 to 1 m / s. The production apparatus for the filament-shaped shaping material and the production apparatus for the resin composition may be the same or different.

[0227] Although the shaped object according to a typical embodiment is formed using a 3D printer that employs the material extrusion deposition (MEX) method, the shaped object according to one embodiment may be formed using a different method, such as powder bed fusion. In the shaped object according to one embodiment, the generation of voids due to foaming in the molten state is suppressed.

[0228] <<Characteristics of the Resin Composition, the 3D Printing Material, and the Modeled Object>> The resin composition, the 3D printing material, and the modeled object can have the following characteristics. Note that the various characteristics (e.g., shear viscosity and extensional viscosity) described above for the resin composition may also be considered to be the same for the 3D printer modeling material or the modeled object.

[0229] <Tensile Yield Strength> In one aspect, the tensile yield strength of the resin composition, the 3D printing modeling material, or the modeled object may be 20 MPa or more, or 50 MPa or more, or 80 MPa or more, and may be 300 MPa or less, or 200 MPa or less, or 150 MPa or less.

[0230] <Tensile Breaking Elongation> In one aspect, the tensile breaking elongation of the resin composition, the 3D printing modeling material, or the modeled object may be 0.5% or more, or 1% or more, or 1.5% or more, and may be 200% or less, or 100% or less, or 20% or less.

[0231] <Flexural Modulus> In one embodiment, the flexural modulus of the resin composition, the 3D printing modeling material, or the shaped object may be 2.0 GPa or more, or 2.5 GPa or more, or 3.0 GPa or more, or 3.5 GPa or more, or 3.7 GPa or more, or 3.9 GPa or more, and may be 20.0 GPa or less, or 10.0 GPa or less, or 8.0 GPa or less.

[0232] <250℃ weight loss rate (T 250℃ ) > 250°C weight loss rate (T 250℃ ) is preferably 1.5% or less, or 1.4% or less, or 1.3% or less, from the viewpoint of avoiding thermal degradation during molding and improving the mechanical strength of the shaped object. A lower weight loss rate at 250°C is desirable, but from the viewpoint of ease of production of the resin composition, the 3D printing modeling material, or the shaped object, in one embodiment, the weight loss rate at 250°C (T 250℃ ) is the weight loss rate when a sample of a resin composition, 3D printing modeling material, or modeled object is held at 250°C under nitrogen flow for 2 hours in TG analysis. The sample is heated from room temperature to 150°C at a temperature increase rate of 10°C / min in a nitrogen flow of 100 ml / min, held at 150°C for 1 hour, then heated from 150°C to 250°C at a temperature increase rate of 10°C / min, and held at 250°C for 2 hours. Starting with the weight W0 at the time when 250°C is reached, and the weight after holding at 250°C for 2 hours as W1, the weight change rate at 250°C (%) is calculated using the following formula: (W0 - W1) / W0 x 100

[0233] <Lightness (L value)> In one embodiment, the L value of the resin composition, 3D printing material, or shaped object is 35 or more, or 40 or more, or 45 or more, and in another embodiment, 90 or less, or 85 or less, or 80 or less. The L value is an index of lightness, and is measured as the L* value using a color difference meter under D65 light and a 10° field of view. When the lightness is high, it is considered that thermal degradation of the cellulose fine fibers is well suppressed in the resin composition, 3D printing material, or shaped object.

[0234] <<Uses of Shaped Articles>> Shaped articles may be used directly for various applications, or may be molded into desired shapes alone or with other components to produce desired molded articles. The method of combining components and the molding method are not particularly limited and may be selected depending on the desired molded article. Examples of molding methods that can be used include, but are not limited to, cutting molding and foam molding. Shaped articles or molded articles are useful as substitutes for steel plates, fiber-reinforced plastics (e.g., carbon fiber-reinforced plastics, glass fiber-reinforced plastics, etc.), resin composites containing inorganic fillers, etc. Suitable uses of shaped articles or molded articles include industrial machine parts, general machine parts, automobile, railway, vehicle, ship, and aerospace-related parts, electronic and electrical parts, construction and civil engineering materials, household goods, sports and leisure goods, housing components for wind power generation, containers and packaging materials, etc.

[0235] <Other Molded Articles> The resin composition of this embodiment is primarily intended for molding using a 3D printer. However, in one aspect, the resin composition may be subjected to molding other than 3D printing, such as injection molding, extrusion molding, compression molding, blow molding, vacuum molding, foam molding, rotational molding, gas injection molding, etc. The lower limit of the molding temperature may be +5°C or +10°C relative to the melting temperature, which is the melting point when the thermoplastic resin is a crystalline resin, or the glass transition point when the thermoplastic resin is an amorphous resin (the highest value when multiple such points are present in the resin composition). Controlling the lower limit within this range can improve molding productivity. The upper limit of the molding temperature may be +100°C, +80°C, +70°C, or +60°C relative to the melting temperature. Controlling the upper limit within this range can suppress deterioration of the cellulose fine fibers, thereby maintaining the mechanical properties of the resin composition. Furthermore, for example, in extrusion molding (e.g., profile extrusion molding), drawdown of the resin composition between the extrusion die and the cooling zone can be suppressed, resulting in good dimensional accuracy of the molded article. Examples of cross-sectional shapes of profile extrusion molded products include sheet, pipe, tube, and angular shapes. In the case of a sheet, the sheet thickness can be 0.2 to 50 mm, and the sheet width can be 10 to 1500 mm. In the case of a pipe or tube, the thickness can be 0.1 to 30 mm, and the inner diameter can be 1 to 1000 mm. In the case of an angular shape, the angle of the corner can be 30 to 150 degrees. Furthermore, the minimum radius of curvature on the valley side of the corner can be 0.1 mm.

[0236] The present disclosure also includes the following items. <Item A> [Item 1] A shaped object comprising a thermoplastic resin and cellulose fine fibers, the shaped object being an output product of a 3D printer, the shaped object having a portion with a thickness of 2.5 mm or more, and at least one 2 mm x 2 mm x 2 mm cubic region selected from the 2.5 mm or more thick portion so as not to include the outermost layer of the shaped object, has a porosity of 10 vol% or less as determined by X-ray computed tomography (CT). [Item 2] The shaped object according to Item 1, wherein there are five 2 mm x 2 mm x 2 mm cubic regions, and the number average value of the porosity for the five regions is 10 vol% or less. [Item 3] The shaped object according to Item 1 or 2, wherein the thermoplastic resin is one or more selected from the group consisting of polyamide-based resins and polyacetal-based resins. [Item 4] The shaped object according to any one of items 1 to 3, wherein the thermoplastic resin comprises a crystalline resin having a melting point of 150°C to 300°C. [Item 5] The shaped object according to any one of items 1 to 4, wherein the cellulose fine fibers have an average fiber diameter of 1,000 nm or less. [Item 6] The shaped object according to any one of items 1 to 5, wherein the cellulose fine fibers are contained in an amount of 1 to 150 parts by mass per 100 parts by mass of the thermoplastic resin. [Item 7] A method for producing the shaped object according to any one of items 1 to 6, comprising ejecting a resin composition containing a thermoplastic resin and cellulose fine fibers from an ejection port of a 3D printer to laminate the resin composition. [Item 8] The method according to item 7, wherein the resin composition is supplied to the 3D printer as a filament-shaped 3D printing material, and a molten 3D printing material is ejected from the ejection port. <Item B> [Item 1] A method for producing a shaped object containing a thermoplastic resin and cellulose fine fibers, comprising: discharging a resin composition containing a thermoplastic resin and cellulose fine fibers from a discharge port of a 3D printer and laminating the resin composition; and adjusting the temperature of the discharge port so that the resin composition is heated at a shear rate of 1000 s -1 exhibiting a shear viscosity of less than 600 kPa.s at an elongation rate of 10 s -1[Item 2] A method for producing a shaped object containing a thermoplastic resin and cellulose fine fibers, comprising: discharging a resin composition containing a thermoplastic resin and cellulose fine fibers from a discharge port of a 3D printer and laminating the resin composition at a shear rate of 1000 s -1 The lowest temperature (T1) at which the resin composition exhibits a shear viscosity of 600 kPa.s or less is -1 a temperature (T3) of the discharge port set to be higher than the temperature (T1) and lower than the temperature (T2) at which the elongational viscosity is 10 kPa s or higher, and the difference between the temperature (T1) and the temperature (T2) is 40°C or higher; [Item 3] The method according to item 1 or 2, wherein the resin composition is supplied to the 3D printer as a filament-shaped 3D printing material, and a melt of the 3D printing material is discharged from the discharge port. [Item 4] The method according to any one of items 1 to 3, wherein the thermoplastic resin is one or more selected from the group consisting of polyamide-based resins and polyacetal-based resins. [Item 5] The method according to any one of items 1 to 4, wherein the thermoplastic resin includes a crystalline resin having a melting point of 150°C to 300°C. [Item 6] The method according to any one of items 1 to 5, wherein the cellulose fine fibers have an average fiber diameter of 1,000 nm or less. [Item 7] The method according to any one of items 1 to 6, wherein the resin composition comprises 1 part by mass to 150 parts by mass of the cellulose fine fibers per 100 parts by mass of the thermoplastic resin. [Item 8] The method according to any one of items 1 to 7, wherein the shaped object has an L value of 35 or more. [Item 9] A resin composition comprising a thermoplastic resin and cellulose fine fibers, wherein the resin composition is sintered at a shear rate of 1000 s -1 The lowest temperature (T1) at which the resin composition exhibits a shear viscosity of 600 kPa.s or less is -1A resin composition, wherein the temperature (T1) is lower than the highest temperature (T2) at which the resin exhibits an extensional viscosity of 10 kPa s or more, and the difference between the temperature (T1) and the temperature (T2) is 40°C or more. [Item 10] The resin composition according to Item 9, wherein the thermoplastic resin is one or more selected from the group consisting of polyamide-based resins and polyacetal-based resins. [Item 11] The resin composition according to Item 9 or 10, wherein the thermoplastic resin comprises a crystalline resin having a melting point of 150°C to 300°C. [Item 12] The resin composition according to any one of Items 9 to 11, wherein the cellulose fine fibers have an average fiber diameter of 1,000 nm or less. [Item 13] The resin composition according to any one of Items 9 to 12, wherein the resin composition comprises 1 part by mass to 150 parts by mass of the cellulose fine fibers per 100 parts by mass of the thermoplastic resin. [Item 14] A modeling material for 3D printing, which is a filament composed of the resin composition according to any one of Items 9 to 13. [Item 15] The 3D printing modeling material according to Item 14, having an L value of 35 or more. [Item 16] A modeled object produced by using a 3D printer to model the resin composition according to any one of Items 9 to 13, or the 3D printing modeling material according to Item 14 or 15. [Item 17] The modeled object according to Item 16, having an L value of 35 or more.

[0237] The following examples further illustrate exemplary embodiments of the present invention, but the present invention is not limited to these examples.

[0238] <Evaluation Method> <Cellulose Fine Fibers> [Average Fiber Length] The average fiber length of the cellulose fine fibers was evaluated by the following method using an automatic fiber shape analyzer (MorfiNeo, manufactured by TechPap).

[0239] The sample was dispersed in pure water to prepare 1 L of an aqueous dispersion. The final solids concentration of the sample was 0.003 to 0.005% by mass. If the sample before dilution was an aqueous dispersion of less than 2% by mass, it was stirred with a spatula. If the sample was an aqueous dispersion of 2% by mass or more, or in the form of a wet cake or powder, it was dispersed using a high-shear homogenizer (manufactured by IKA, trade name "Ultra Turrax T18") under the following processing conditions: rotation speed 25,000 rpm x 5 minutes.

[0240] Next, the aqueous dispersion prepared above was subjected to measurement using an autosampler. The measurement results obtained were output in txt format, and the value of Mean Length-Weighted Length [μm] was adopted as the average fiber length.

[0241] [Average fiber diameter] The aqueous dispersion of cellulose fine fibers obtained in each production example was diluted with tert-butanol to 0.01% by mass, and dispersed using a high-shear homogenizer (manufactured by IKA, trade name "Ultra Turrax T18") under processing conditions of 15,000 rpm for 3 minutes. The dispersion was cast onto an osmium-deposited silicon substrate, air-dried, and measured with a high-resolution scanning electron microscope (manufactured by Hitachi High-Technologies Corporation, Regulus 8220). The measurement was performed by adjusting the magnification so that at least 100 cellulose fibers could be observed, and the minor axes of 100 randomly selected cellulose fibers were measured, and the arithmetic average of the 100 cellulose fine fibers was calculated.

[0242] [DS] (Preparation of porous sheet) The wet cake was added to tert-butanol, and further dispersed using a mixer or the like until no aggregates remained. The concentration was adjusted to 0.5% by mass relative to 0.5 g of cellulose fine fiber solids. 100 g of the obtained tert-butanol dispersion was filtered on filter paper. Without peeling the filtered material from the filter paper, it was sandwiched together with the filter paper between two larger pieces of filter paper, and dried in an oven at 150°C for 5 minutes while pressing down the edges of the larger filter paper with weights. The filter paper was then peeled off to obtain a porous sheet with little distortion. The air permeability resistance of this sheet was 10 g / m2. 2 The porous sheet was used as a measurement sample. The basis weight W (g / m 2 After measuring the air permeability, the air permeability resistance R (sec / 100 ml) was measured using an Oken type air permeability resistance tester (manufactured by Asahi Seiko Co., Ltd., model EG01). 2 The value per unit area was calculated. 2 Air resistance per unit area (sec / 100 ml) = R / W x 10 If the air resistance of this sheet is 10 g / m 2A porous sheet having a water content of 100 sec / 100 ml or less was obtained.

[0243] (Measurement) The infrared spectrum of the porous sheet was measured by the ATR-IR method at five points using a Fourier transform infrared spectrophotometer (FT / IR-6200 manufactured by JASCO Corporation). The infrared spectrum measurement was carried out under the following conditions: Number of accumulations: 64, Wavenumber resolution: 4 cm -1 Measurement wave number range: 4000 to 600 cm -1 , ATR crystal: diamond, incident angle: 45° From the obtained IR spectrum, the IR index was calculated according to the following formula: IR index = H1730 / H1030, where H1730 and H1030 are the wavelengths at 1730 cm -1 , 1030 cm -1 (absorption band of C-O stretching vibration of cellulose backbone chain). -1 and 1500 cm -1 The line connecting the -1 and 1500 cm -1 The line connecting these points is taken as the baseline, and the absorbance is calculated when this baseline is taken as 0. The average degree of substitution at each measurement point was calculated from the IR index according to the following formula, and the average value was taken as DS: DS = 4.13 × IR index

[0244] [Crystallization degree] The crystallinity of the cellulose raw material was evaluated using an X-ray diffractometer (MiniFlex II, manufactured by Rigaku Corporation) by the following method. X-ray diffraction measurement was performed on the porous sheet described above, and the crystallinity was calculated using the following formula: Crystallinity (%) = [I (200) -I (amorphous) ] / I (200) ×100 I (200) : Diffraction peak intensity due to the 200 plane (2θ = 22.5°) in cellulose type I crystal (amorphous): The halo peak intensity due to amorphous in cellulose type I crystals, which is the peak intensity at an angle 4.5° lower than the diffraction angle of the 200 plane (2θ = 18.0°) (X-ray diffraction measurement conditions) Apparatus: MiniFlex (manufactured by Rigaku Corporation) Operation axis: 2θ / θ Radiation source: CuKα Measurement method: Continuous Voltage: 40 kV Current: 15 mA Start angle: 2θ = 5° End angle: 2θ = 30° Sampling width: 0.020° Scan rate: 2.0° / min Sample: A porous sheet was attached to a sample holder

[0245] [Weight-average molecular weight (Mw), Mw / Mn ratio] 0.88 g of the porous sheet described above was weighed and chopped into small pieces with scissors. After lightly stirring, 20 mL of pure water was added and the mixture was left for one day. Next, the water and solids were separated by centrifugation. Subsequently, 20 mL of acetone was added, the mixture was lightly stirred, and the mixture was left for one day. Next, the acetone and solids were separated by centrifugation. Subsequently, 20 mL of N,N-dimethylacetamide was added, the mixture was lightly stirred, and the mixture was left for one day. Again, the N,N-dimethylacetamide and solids were separated by centrifugation, and then 20 mL of N,N-dimethylacetamide was added, the mixture was lightly stirred, and the mixture was left for one day. The N,N-dimethylacetamide and solids were separated by centrifugation, and 19.2 g of an N,N-dimethylacetamide solution prepared so that lithium chloride was 8 mass percent was added to the solids. The mixture was stirred with a stirrer, and dissolution was confirmed visually. The solution in which the cellulose was dissolved was filtered through a 0.45 μm filter, and the filtrate was used as a sample for gel permeation chromatography. The apparatus and measurement conditions used were as follows.

[0246] Apparatus: Tosoh HLC-8120 Column: TSKgel SuperAWM-H (6.0 mm ID x 15 cm) x 2 Detector: RI detector Eluent: N,N-dimethylacetamide (lithium chloride 0.2%) Flow rate: 0.6 mL / min Calibration curve: pullulan equivalent

[0247] [Average alkali-soluble polysaccharide content] The alkali-soluble polysaccharide content was determined by subtracting the α-cellulose content from the holocellulose content (Wise method) using the method described in a non-patent document for cellulose fine fibers (Wood Science Experiment Manual, edited by the Japan Wood Research Society, pp. 92-97, 2000). The alkali-soluble polysaccharide content was calculated three times for each sample, and the number average of the calculated alkali-soluble polysaccharide contents was used as the average alkali-soluble polysaccharide content of the cellulose fine fibers. For acetylated cellulose fine fibers, the average alkali-soluble polysaccharide content of the raw material before acetylation was used.

[0248] [Thermal decomposition onset temperature] Thermal analysis of the porous sheet was carried out by the following measurement method. Apparatus: Thermo plus EVO2 manufactured by Rigaku Corporation Sample: 10 mg of circular samples cut out from the porous sheet were placed in an aluminum sample pan in a stack. Sample amount: 10 mg Measurement conditions: In a nitrogen flow of 100 ml / min, the temperature was increased from room temperature to 150°C at a rate of 10°C / min, and then held at 150°C for 1 hour, and then the temperature was increased to 450°C at a rate of 10°C / min. T D Calculation method: The calculation was performed from a graph with the horizontal axis being temperature and the vertical axis being weight residual rate %. The temperature was further increased from the weight (weight loss 0 wt%) of the porous sheet at 150°C (a state where moisture was almost completely removed) as the starting point, and a straight line was obtained that passed through the temperatures at 1 wt% weight loss and 2 wt% weight loss. The temperature at the point where this straight line intersects with the horizontal line (baseline) that passes through the starting point of 0 wt% weight loss was determined as the thermal decomposition onset temperature (T D )

[0249] [1wt% weight loss temperature] T D The temperature at which a 1 wt % weight loss was achieved was used in the calculation as the 1 wt % weight loss temperature.

[0250] [Weight change rate at 250°C] Apparatus: Thermo plus EVO2 manufactured by Rigaku Corporation Sample: Circular pieces cut out from the porous sheet were placed in an aluminum sample pan in layers of 10 mg. Sample amount: 10 mg Measurement conditions: In a nitrogen flow of 100 ml / min, the temperature was increased from room temperature to 150°C at a rate of 10°C / min, and then held at 150°C for 1 hour. The temperature was increased from 150°C to 250°C at a rate of 10°C / min, and then held at 250°C for 2 hours. The weight W0 at the time of reaching 250°C was used as the starting point, and the weight after holding at 250°C for 2 hours was taken as W1, and the weight change rate at 250°C (%) was calculated using the following formula: (W0-W1) / W0×100

[0251] <Thermoplastic Resin> [Melting Point] Measured by the method described in JIS K7121.

[0252] [Crystallization degree] It was measured by the method described in JIS K7122. The difference between the heat of fusion (J / g) calculated from the area of ​​the melting peak and the heat of crystallization (J / g) calculated from the area of ​​the crystallization peak was divided by the theoretical heat of fusion of complete crystallization of the base resin (the component with the higher copolymerization ratio in the case of a copolymer). The obtained ratio was taken as the crystallinity (%). The theoretical heat of fusion values ​​used were 241 J / g for polyamide 6, 254 J / g for polyamide 610, and 220 J / g for polyacetal.

[0253] <Resin composition> [Shear rate of resin composition: 1000 sec -1 Shear viscosity and elongation rate at 10 s -1 Shear viscosity and extensional viscosity were determined using a twin capillary rheometer (manufactured by Malvern, model RH-10). Long die length: 16 mm Long die diameter: 1 mm Short die length: 0.25 mm Short die diameter: 1 mm Die inlet angle: 90 degrees Temperature: Measurements were made for each material in 5°C increments in the following ranges: (Polyamide 6, Polyamide 610) 230 to 300°C (Polyamide 6 / 66) 210 to 300°C (Polyacetal) 180 to 250°C From the obtained viscosity curves, the shear viscosity was calculated at a shear rate of 1000 s -1The lowest temperature (T1) at which the shear viscosity is 600 kPa.s or less and the elongation rate is 10 s -1 The maximum temperature (T2) at which the elongational viscosity was 10 kPa.s or more was calculated.

[0254] [Mechanical Strength of Resin Composition] (Flexural Properties) Using an injection molding machine, the resin compositions were molded under conditions conforming to JIS K7364-2. The molding temperatures were 260°C for polyamide 6, 265°C for polyamide 610, and 230°C for PA6 / 66. The test specimen shape was based on the dumbbell shape of JIS K7113 (out of print) No. 2, with the dimensions modified to be as shown in Figure 3 and a thickness of 3 mm. The values ​​in the figure are in millimeters. The molded test specimens were subjected to a bending test conforming to ISO178, and the bending strength and bending modulus were measured.

[0255] [Lightness (L value) of resin composition and molded object] The L* value was measured using a color difference meter (CM-2002 manufactured by Konica Minolta) under D65 light and a 10° visual field.

[0256] <Shaped Object> [Porosity] Five cubic regions measuring 2 mm x 2 mm x 2 mm were selected from a dumbbell-shaped object. Specifically, the dumbbell shape was divided into five equal parts in the longitudinal direction, designated as regions 1 to 5, and a cubic region was defined centered on the center of each region (i.e., the center in the thickness direction, longitudinal direction, and lateral direction). X-ray CT analysis was performed on each cubic region under the following conditions. In the obtained three-dimensional image, voids present in the cubic region were identified, and the ratio of the total volume of the voids to the total volume of the cubic region was calculated. The results are shown in Table 3. FIG. 4 is a three-dimensional image of region 3 of Example A1 obtained by X-ray CT, and FIG. 5 is a three-dimensional image of region 3 of Comparative Example A1 obtained by X-ray CT. Equipment: Bruker X-CT Skyscan 1272 (analysis software: CT-An) Tube voltage: 40 kV Tube current: 100 μA X-ray filter: None Number of pixels: 2452 × 1640 pix Pixel resolution: 4.0 μm Number of integrations: 4 Scan: Every 0.3°, 180° scan Analysis processing: Smoothing using Kuwahara filter (2-pixel area)

[0257] [Mechanical Strength of Shaped Object] A bending test was carried out in accordance with ISO 178 on the dumbbell-shaped objects formed as described below, and the bending strength and bending modulus were measured.

[0258] [Appearance of the molded object] The appearance of the molded object was evaluated as follows: Excellent: No problem with appearance Good: Some fluffing and foaming observed Poor: Dripping and stringiness occurred in the molded object

[0259] [Appearance of the molded product (fluffing)] The appearance of the molded product was evaluated as follows: Good: No problem with the appearance. Poor: Fluffing was observed on the molded product.

[0260] <Moldability> [Drawdown during production of filament-shaped modeling material] The shape of the filament drawn from the filament extruder was observed and evaluated according to the following criteria: Good: Filamentization was possible without any problems. Fair: Parts of the filament had an uneven diameter.

[0261] [Stringiness during molding] The molded object was observed and evaluated according to the following criteria: Good: No problem with appearance. Poor: Stringiness was observed in the molded object.

[0262] [Ease of Forming] The behavior during forming was observed and evaluated according to the following criteria: Good: Forming was possible without any problems. Fair: Discharge was unstable, but a model was possible. Poor: Discharge was unstable, and a model could not be formed.

[0263] <Materials Used> <Cellulose Fine Fibers> Cellulose fine fibers obtained according to the following production example were used. (Production Example 1: CNF-1) Cotton Linter Pulp (CLP) Cotton crude linter was dry screened in a laboratory to collect a 2-8 mm fraction. Next, 400 g of the resulting crude linter was introduced into a 4 L autoclave and cooked at an active alkali addition rate of 18 ((NaOH (g) + NaS (g)) / 1 L of water), a sulfidity of 28% (NaS (g) / total alkali (g) × 100), a liquor ratio of 4.5 (liquid / solids), an initial temperature of 90°C, a cooking temperature of 155°C, and a cooking time of 150 minutes. The cooked crude linter was diluted 10-fold with pure water and washed by decantation four times. It was then dehydrated to a solids content of 25% by mass using a centrifugal dehydrator (equipped with a filter cloth with 200 μm mesh).

[0264] The crude linter obtained above was dried, and 70.0 g of the dried product was placed in a polyethylene (PE) plastic bottle. Pure water was added and sealed so that the solid content concentration during the reaction was 10% by mass. The container was then immersed in a constant temperature water bath and preheated at 70 ° C. After preheating, sodium hydroxide was added to the water in the container so that the concentration was 10% by mass, and the mixture was stirred with a 3-1 motor to dissolve the sodium hydroxide. This slurry was introduced into a 2 L autoclave equipped with a stirring blade, heated to 90 ° C, and then oxygen was introduced, the internal pressure was increased to 500 kPa, and the reaction was carried out for 60 minutes. The linter after the reaction was washed with ion-exchanged water and then dehydrated to a solid content of 25% by mass using a centrifugal dehydrator (equipped with a filter cloth with a mesh size of 200 μm) to obtain a cellulose raw material.

[0265] The resulting cellulose raw material had a crystallinity of 85% and a glucose content of 98% by mass.

[0266] The above procedure was repeated multiple times, and the recovered cellulose raw material was immersed in water to a solids content of 1.0% by mass. The cellulose raw material was then dispersed using a lab pulper (manufactured by Aikawa Iron Works Co., Ltd.) and defibrated using a single-disc refiner (manufactured by Aikawa Iron Works Co., Ltd., SDR14 type lab refiner, pressurized disc type). This disc refiner had two tanks (tank A and tank B) connected by piping via a device. The slurry was first transferred from tank A to tank B via the disc refiner and stored there. After the slurry in tank A was processed, the slurry was continuously transferred from tank B to tank A via the disc refiner and stored there. This method controlled the number of passes through the disc refiner for processing. The disc refiner's blade spacing adjustment mechanism was equipped with a ball screw jack and a reducer, allowing for precise blade spacing adjustment with micrometer accuracy. The deviation of the blade distance during beating after reaching the target distance was 0.005 mm or less as measured by a displacement sensor. The disc refiner blades used were blades with a blade width of 4.0 mm and a blade groove ratio of 0.89, and after 30 passes at a blade distance of 0.25 mm, blades with a blade width of 0.8 mm and a blade groove ratio of 0.53 were used, and after 30 passes at a blade distance of 0.30 mm.

[0267] The obtained slurry was subjected to 10 passes at 80 MPa using a high-pressure homogenizer (NS3015H, manufactured by Niro Soavi Co., Ltd.). Similar to the disc refiner treatment, the high-pressure homogenizer treatment was also performed using two tanks, and the number of passes was controlled. Cellulose fine fibers CNF-1 were obtained by the above method.

[0268] (Production Example 2: CNF-2) Acetylated Cotton Linter Pulp Using the cellulose raw material obtained in the production method of Production Example 1, a dispersion of cellulose in dimethyl sulfoxide (DMSO) to a solids content of 5.8% by mass and potassium carbonate to 1.1% by mass was prepared. 30 L of this slurry was placed in a 50 L reaction vessel and heated to 60°C while stirring homogeneously. Vinyl acetate (4.4% by mass relative to the reaction solution) was added, and acetylation was carried out until a predetermined degree of substitution was achieved. During the reaction, the degree of substitution (DS) was measured as appropriate, and when the DS reached 1.0 or greater, 3 L of water was added to terminate the reaction. This reaction solution was stirred and filtered repeatedly using a pressure filter with pure water in an amount 50 times the mass of the cellulose solids, thoroughly washing out the solvent and the like, yielding a wet cake of acetylated cellulose fibers.

[0269] This acetylated cellulose was subjected to a micronization treatment by the method of Production Example 1 to obtain cellulose microfibers CNF-2. The DS of the cellulose microfibers was 0.85.

[0270] (Production Example 3: CNF-3) A commercially available product (Cerish: KY100G) was used as is.

[0271] <Thermoplastic resin> Polyamide PA6: 1022B (manufactured by Ube Industries, Ltd.), melting point 225°C PA610: 3400 (manufactured by Asahi Kasei Corporation), melting point 225°C PA6 / 66: 5023 (manufactured by Ube Industries, Ltd.), melting point 196°C Polyacetal: HC450 (manufactured by Asahi Kasei Corporation), melting point 170°C

[0272] <Stabilizer> Antioxidant: Irganox 245 manufactured by BASF

[0273] <Dispersant> Polyethylene glycol-polypropylene glycol copolymer (PEG-PPG): Sannix GL-3000 Polyethylene glycol (PEG): PEG6000 (manufactured by Sanyo Chemical Industries, Ltd.)

[0274] <<Production of resin composition and modeling material for 3D printer>> [Production of resin composition] (Preparation Examples 1 to 7, 9) Resin compositions were produced using the cellulose fine fiber aqueous dispersions of each of Production Examples 1 to 3 as shown in Table 2, according to the following procedure. The cellulose fine fiber aqueous dispersions were subjected to pressure filtration to obtain aqueous dispersions with a solids content of 10% by mass. PEG-PPG or PEG was added to this cellulose fine fiber aqueous dispersion in an amount of 30 parts by mass per 70 parts by mass of cellulose fine fibers, and then the mixture was vacuum dried at about 40°C using a revolution / rotation type mixer (Hibismix 2P-1, manufactured by Primix Corporation), to obtain cellulose fine fiber powder.

[0275] A twin-screw extruder (TEM SX series extruder manufactured by Toshiba Machine Co., Ltd.) with 13 cylinder blocks and an L / D ratio of 52 was used. A side feed port was installed in cylinder 5 to enable the supply of raw materials from that position, and a vent port for vacuum suction was installed in cylinder 12 to enable the removal of volatile components and coexisting air.

[0276] The screw configuration was as follows: cylinders 1 and 2 served as conveying screws; cylinders 3 and 4 were provided with two clockwise kneading discs (feed type kneading discs: hereinafter referred to as RKDs), followed by one neutral kneading disc (non-conveying type kneading disc: hereinafter referred to as NKDs), followed by a counterclockwise screw, forming a pre-mixing zone; cylinder 5, which was the side feed zone, served as a conveying screw; cylinders 6 and 7 were provided with one RKD, two NKDs, followed by one counterclockwise screw, forming a melt-kneading zone. Cylinders 8 and 9 served as conveying screws; cylinder 10 was provided with one RKD, followed by one NKD, followed by a counterclockwise screw, forming a kneading zone. Cylinders 11 to 13 served as conveying screws, forming a devolatilization zone.

[0277] A mixture containing a thermoplastic resin and cellulose fine fiber powder in the ratios shown in Table 2 was fed through cylinder 1 of an extruder, with cylinder 1 water-cooled and the other cylinders set to 200 to 300°C, kneaded, and extruded into a strand shape. The strand was cut with a strand cutter to obtain resin composition pellets. These resin composition pellets were injection molded into dumbbell-shaped test pieces. These resin composition pellets were also used to produce filaments, as described below.

[0278] (Preparation Example 8) Purified water was added to the cellulose fine fibers (Celish KY100G) of Production Example 3, and the mixture was stirred in a mixer to prepare an aqueous dispersion containing 3% by mass of cellulose fibers. 100 parts by mass of the aqueous dispersion and 100 parts by mass of ε-caprolactam were further stirred and mixed in a mixer until a uniform solution was obtained. Subsequently, this mixed solution was heated to 240°C with stirring, and gradually released water vapor, while the pressure was increased to 0 kgf / cm. 2 to 7 kgf / cm 2 The pressure was increased to 1000 kJ / min. The pressure was then released to atmospheric pressure, and a polymerization reaction was carried out at 240°C for 1 hour. When the polymerization was completed, the obtained resin composition was discharged and cut into pellets. The obtained pellets were treated with hot water at 95°C, refined, and dried. The resin composition pellets were injection molded into dumbbell-shaped test pieces. The resin composition pellets were also used to produce filaments, which will be described later.

[0279] [Production of filament] Using the resin composition pellets produced above, a 3devo filament extruder (nozzle diameter 1.7 mm) manufactured by 3D Printing Corporation was used. The extruder was taken up under automatic control conditions of a nozzle temperature of 250°C, a screw rotation speed of 3.5 rpm, and a take-up speed of 0.02 to 0.1 m / s under air-cooled conditions to obtain a monofilament as a filament-shaped shaping material.

[0280] <<Production of 3D Printer-Modeled Objects>> [Examples A1 to A6, Comparative Examples A2 to A4, Examples B1 to B8, Comparative Examples B1 to B8] The filament-shaped modeling materials produced above were dried in a vacuum dryer at 80°C for 3 hours, and then a dumbbell-shaped object with the dimensions and thickness of 3 mm shown in Figure 3 was obtained using a FUNMAT HT material extrusion lamination (MEX) 3D printer manufactured by Intamsys under the modeling conditions shown in Tables 3 and 4. The lamination direction was alternated between 45° and 135° relative to the longitudinal direction of the dumbbell, and two walls were formed on the outermost layer.

[0281] Comparative Example A1 A dumbbell-shaped object was obtained in the same manner as in Example A1 using PolyMide PA6-CF: a resin composition containing polyamide 6 and carbon fiber (commercially available from Polymaker).

[0282]

[0283]

[0284]

[0285]

[0286] In Comparative Examples A2, A3, and A4, it is believed that the deterioration of appearance and the increase in porosity due to foaming occurred because the melt viscosity of the resin composition decreased due to thermal degradation of the cellulose fine fibers during kneading and shaping.

[0287] The shaped article provided by the present invention can be suitably applied to a wide range of uses.

Claims

1. A molded object comprising a thermoplastic resin and cellulose microfibers, The aforementioned molded object is an output from a 3D printer. The aforementioned molded object has a portion with a thickness of 2.5 mm or more. A fabricated object in which at least one 2 mm × 2 mm × 2 mm cubic region selected from the aforementioned parts with a thickness of 2.5 mm or more has a porosity of 10 volume percent or less as determined by X-ray computed tomography (CT).

2. The molded object according to claim 1, wherein the cubic region is a region selected so as not to include the outermost layer of the molded object.

3. The molded object according to claim 1 or 2, wherein there are five cubic regions of at least one 2 mm × 2 mm × 2 mm, and the number average value of the void ratios in the five regions is 10 volume percent or less.

4. The molded product according to claim 1 or 2, wherein the thermoplastic resin includes a polyamide resin.

5. The fabricated object according to claim 1 or 2, wherein the degree of crystallinity of the fabricated object, as measured using a differential scanning calorimeter (DSC), is 50% or less.

6. The molded product according to claim 1 or 2, wherein the thermoplastic resin includes a crystalline resin having a melting point of 150°C to 300°C.

7. The molded product according to claim 1 or 2, wherein the cellulose microfibers have an average fiber diameter of 1000 nm or less.

8. The molded product according to claim 1 or 2, comprising 1 to 150 parts by mass of the cellulose fine fibers per 100 parts by mass of the thermoplastic resin.

9. A method for manufacturing a molded object according to claim 1 or 2, A method comprising extruding and layering a resin composition containing a thermoplastic resin and cellulose microfibers from the extrusion port of a 3D printer.

10. The resin composition is supplied to the 3D printer as a filament-like 3D printing material. The method according to claim 9, wherein the molten material for 3D printing is discharged from the discharge port.

11. A method for manufacturing a molded object containing a thermoplastic resin and cellulose microfibers, The method includes extruding a resin composition containing a thermoplastic resin and cellulose microfibers from the extrusion port of a 3D printer and layering them, The aforementioned molded object has a portion with a thickness of 2.5 mm or more. A method comprising selecting at least one 2 mm × 2 mm × 2 mm cubic region from the aforementioned region with a thickness of 2.5 mm or more, wherein the porosity determined by X-ray computed tomography (CT) is 10 volume percent or less.

12. A method for manufacturing a molded object containing a thermoplastic resin and cellulose microfibers, The process involves extruding a resin composition containing a thermoplastic resin and cellulose microfibers from the extrusion port of a 3D printer and layering the resulting material. The temperature of the discharge port is determined when the resin composition has a shear rate of 1000 seconds. -1 The shear viscosity was less than 600 Pa·s and the extension rate was 10 seconds. -1 A method for setting the temperature to one that exhibits an extensional viscosity of more than 10 kPa·s.

13. A method for manufacturing a molded object containing a thermoplastic resin and cellulose microfibers, The process involves extruding a resin composition containing a thermoplastic resin and cellulose microfibers from the extrusion port of a 3D printer and layering the resulting material. The resin composition is subjected to a shear rate of 1000 seconds. -1 The lowest temperature (T1) at which the shear viscosity is 600 Pa·s or less is when the resin composition is elongated at a rate of 10 seconds -1 The temperature is lower than the highest temperature (T2) at which the extensional viscosity is 10 kPa·s or higher, and the difference between the temperature (T1) and the temperature (T2) is 40°C or more. A method for setting the temperature (T3) of the discharge port to be greater than the temperature (T1) and less than the temperature (T2).

14. The aforementioned molded object has a portion with a thickness of 2.5 mm or more. The method according to claim 12 or 13, wherein at least one 2 mm × 2 mm × 2 mm cubic region selected from the portion with a thickness of 2.5 mm or more has a porosity of 10 volume% or less as determined by X-ray computed tomography (CT).

15. A resin composition comprising a thermoplastic resin and cellulose fine fibers, The resin composition is subjected to a shear rate of 1000 seconds. -1 The lowest temperature (T1) at which the shear viscosity is 600 Pa·s or less is when the resin composition is elongated at a rate of 10 seconds -1 The temperature at which the extensional viscosity is 10 kPa·s or higher is lower than the maximum temperature (T2) at which it is observed. A resin composition in which the difference between the temperature (T1) and the temperature (T2) is 40°C or more.

16. A 3D printing material comprising a filament composed of the resin composition described in claim 15.

17. A molded object obtained by 3D printing using a resin composition according to claim 15 or a 3D printing material according to claim 16.