WO2023008497A1 - セルロース微細繊維及びその製造方法、不織布、並びに繊維強化樹脂及びその製造方法 - Google Patents
セルロース微細繊維及びその製造方法、不織布、並びに繊維強化樹脂及びその製造方法 Download PDFInfo
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- 229910052794 bromium Inorganic materials 0.000 description 1
- QHIWVLPBUQWDMQ-UHFFFAOYSA-N butyl prop-2-enoate;methyl 2-methylprop-2-enoate;prop-2-enoic acid Chemical compound OC(=O)C=C.COC(=O)C(C)=C.CCCCOC(=O)C=C QHIWVLPBUQWDMQ-UHFFFAOYSA-N 0.000 description 1
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- QIQXTHQIDYTFRH-UHFFFAOYSA-N octadecanoic acid Chemical compound CCCCCCCCCCCCCCCCCC(O)=O QIQXTHQIDYTFRH-UHFFFAOYSA-N 0.000 description 1
- OQCDKBAXFALNLD-UHFFFAOYSA-N octadecanoic acid Natural products CCCCCCCC(C)CCCCCCCCC(O)=O OQCDKBAXFALNLD-UHFFFAOYSA-N 0.000 description 1
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- XNGIFLGASWRNHJ-UHFFFAOYSA-L phthalate(2-) Chemical compound [O-]C(=O)C1=CC=CC=C1C([O-])=O XNGIFLGASWRNHJ-UHFFFAOYSA-L 0.000 description 1
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- 229920001225 polyester resin Polymers 0.000 description 1
- 239000004645 polyester resin Substances 0.000 description 1
- 239000009719 polyimide resin Substances 0.000 description 1
- 229920001228 polyisocyanate Polymers 0.000 description 1
- 239000005056 polyisocyanate Substances 0.000 description 1
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- 239000004926 polymethyl methacrylate Substances 0.000 description 1
- 229920001451 polypropylene glycol Polymers 0.000 description 1
- 239000004800 polyvinyl chloride Substances 0.000 description 1
- 229920000915 polyvinyl chloride Polymers 0.000 description 1
- 229920000131 polyvinylidene Polymers 0.000 description 1
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- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
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- 239000012783 reinforcing fiber Substances 0.000 description 1
- 239000012763 reinforcing filler Substances 0.000 description 1
- 239000012779 reinforcing material Substances 0.000 description 1
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- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 1
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- PXXNTAGJWPJAGM-UHFFFAOYSA-N vertaline Natural products C1C2C=3C=C(OC)C(OC)=CC=3OC(C=C3)=CC=C3CCC(=O)OC1CC1N2CCCC1 PXXNTAGJWPJAGM-UHFFFAOYSA-N 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 230000004580 weight loss Effects 0.000 description 1
- 229920001221 xylan Polymers 0.000 description 1
- 150000004823 xylans Chemical class 0.000 description 1
- 239000002888 zwitterionic surfactant Substances 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
- B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
- B29C70/06—Fibrous reinforcements only
- B29C70/10—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres
- B29C70/12—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres using fibres of short length, e.g. in the form of a mat
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
- B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
- B29C70/28—Shaping operations therefor
- B29C70/40—Shaping or impregnating by compression not applied
- B29C70/42—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
- C08B3/00—Preparation of cellulose esters of organic acids
- C08B3/20—Esterification with maintenance of the fibrous structure of the cellulose
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/04—Reinforcing macromolecular compounds with loose or coherent fibrous material
- C08J5/06—Reinforcing macromolecular compounds with loose or coherent fibrous material using pretreated fibrous materials
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F2/00—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof
- D01F2/24—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof from cellulose derivatives
- D01F2/28—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof from cellulose derivatives from organic cellulose esters or ethers, e.g. cellulose acetate
-
- D—TEXTILES; PAPER
- D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
- D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
- D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
- D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
- D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
- D04H1/425—Cellulose series
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
- D21H11/16—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only modified by a particular after-treatment
- D21H11/18—Highly hydrated, swollen or fibrillatable fibres
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
- D21H11/16—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only modified by a particular after-treatment
- D21H11/20—Chemically or biochemically modified fibres
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H15/00—Pulp or paper, comprising fibres or web-forming material characterised by features other than their chemical constitution
- D21H15/02—Pulp or paper, comprising fibres or web-forming material characterised by features other than their chemical constitution characterised by configuration
Definitions
- the present invention relates to a cellulose fine fiber and its manufacturing method, a nonwoven fabric, a fiber-reinforced resin using the same, and its manufacturing method.
- cellulose fibers especially cellulose fine fibers
- resins containing cellulose fine fibers are highly brittle and are broken even by small changes, so there are still problems in terms of strength and impact resistance.
- Patent Document 1 by combining a resin having a specific relative viscosity and carboxy terminal concentration with acetylated microfibrillated cellulose fibers, bending strength and bending elastic modulus are improved while maintaining impact resistance. technology is described.
- Patent Document 2 describes microfibrillated cellulose having an average fiber length of 0.02 to 3.0 mm, an average fiber diameter of 0.1 ⁇ m or more, and a fibrillation rate of 1.0% or more.
- a technique for increasing the flexural modulus of a fiber-reinforced composite resin by adding it to the resin after treatment is described.
- Patent Document 3 discloses a composite material consisting of three components, microfibrillated cellulose, an elastomer, and a resin. It is stated that it can improve performance.
- Patent Document 1 uses pulp called lignocellulose in which a certain amount of lignin remains, so there is a problem with heat resistance during melt-kneading.
- defibration is performed under the restricted shearing force of the kneading and extrusion process, fibrillation does not occur sufficiently to develop performance, and even if the properties of the resin are improved, a composite of resin and cellulose strength and modulus are still insufficient.
- Patent Document 2 sufficient consideration is not given to satisfying high levels of strength, elastic modulus, and breaking strain.
- the prior art has not provided a fiber-reinforced resin that satisfies high levels of strength, elastic modulus, and breaking strain at the same time.
- the problem to be solved by the present invention is to provide cellulose fine fibers that give a fiber-reinforced resin that is excellent in all of strength, elastic modulus, and breaking strain.
- the number frequency of fibers having a fiber length of 411 ⁇ m or more among the fibers having a fiber length of 100 ⁇ m or more is 30% or less
- the fibrillation rate is 5% or less
- the cellulose fine fiber according to item 1 or 2 which satisfies all of [4]
- [5] In a scanning electron microscope (SEM) image of the surface of a sample obtained by casting and drying a 5 mass ppm DMSO dispersion of cellulose fine fibers, the area occupied by the cellulose fine fibers is less than 15 ⁇ m 2 .
- Cellulose fine fibers according to any one of items 1 to 4 wherein the proportion of the total area occupied by the fibers is 10% or more and 80% or less.
- the cellulose fine fiber according to any one of items 1 to 10 wherein the number frequency of fibers having a fiber length of 411 ⁇ m or more is 30% or less among the fibers having a fiber length of 100 ⁇ m or more.
- the cellulose fine fibers according to any one of items 1 to 12 wherein the number frequency of fibers having a fiber length of 20 ⁇ m or more and 56 ⁇ m or less is 30% or more and 75% or less among the fibers having a fiber length of less than 100 ⁇ m.
- the cellulose fine fiber according to any one of items 1 to 16, further satisfying [18] A method for producing cellulose fine fibers according to any one of items 1 to 17, The halogen content of the cellulose fine fibers is 250 mass ppm or less, and the method comprises A method for producing cellulose fine fibers, comprising a step of defibrating a cellulose raw material having a halogen content of 300 ppm by mass or less.
- a fiber-reinforced resin comprising the cellulose fine fibers according to any one of items 1 to 17 and a resin.
- 20. The fiber-reinforced resin according to item 19, wherein the resin has a melting point of 200° C. or higher.
- a nonwoven fabric comprising the cellulose microfibers according to any one of items 1-17.
- 23. The nonwoven fabric according to Item 22, containing 50% by mass or more of synthetic fibers having a melting point of 300° C. or less.
- 24. The nonwoven fabric according to item 22 or 23, containing 1% by mass or more of the cellulose fine fibers.
- a fiber-reinforced resin comprising the nonwoven fabric according to any one of items 22 to 24 and a resin impregnated in the nonwoven fabric.
- a method for producing a fiber-reinforced resin containing cellulose fine fibers and a resin comprising: A step of hot-pressing the nonwoven fabric according to any one of items 22 to 24 to obtain a fiber reinforced resin, A method for producing a fiber-reinforced resin, wherein the nonwoven fabric contains synthetic fibers, and the heat pressing is performed at a melting point of the synthetic fibers or higher.
- Cellulose fine fibers related to one aspect of the present invention can provide cellulose fine fibers that give a fiber-reinforced resin that is excellent in all of strength, elastic modulus, and breaking strain.
- FIG. 10 is an explanatory diagram of a calculation method of an IR index 1730 and an IR index 1030;
- FIG. 4 is a diagram illustrating an arrangement example of blades and grooves of a disc refiner; It is a figure explaining blade width of a disc refiner, groove width, and distance between blades.
- the average fiber length of the cellulose fine fibers is 110 ⁇ m or more and 500 ⁇ m or less.
- Cellulose fine fibers in a fiber shape automatic analyzer, (i) an average fiber length of 130 ⁇ m or more and 350 ⁇ m or less; (ii) an average fiber diameter of 35 ⁇ m or less, (iii) a fine fiber area ratio of 75% or less, (iv) Among fibers with a fiber length of less than 100 ⁇ m, the number frequency of fibers having a fiber length of 20 ⁇ m or more and 56 ⁇ m or less is 75% or less, (v) the number frequency of fibers having a fiber length of 411 ⁇ m or more among the fibers having a fiber length of 100 ⁇ m or more is 30% or less, and (vi) the fibrillation rate is 5% or less, meet all of
- Cellulose fine fibers are cellulose raw materials that have been made finer using at least one physical means, and are generally called cellulose nanofibers, CNF, CeNF, fine cellulose fibers, etc. be done.
- the cellulose microfibers are chemically modified cellulose microfibers.
- chemically modified cellulose microfibers means cellulose microfibers in which at least a portion of the three hydroxyl groups contained in the glucopyranose units in the cellulose molecule skeleton present in the cellulose microfibers is chemically modified. do.
- the term "partially” as used herein means that at least one hydroxyl group of at least one glucopyranose unit in the cellulose structure in which a plurality of glucopyranose units are polymerized is chemically modified.
- the entire cellulose is not chemically modified, and the chemically modified cellulose microfibers retain the crystalline structure of the cellulose prior to chemical modification.
- the crystal structure of cellulose type I can be confirmed when analyzed by X-ray diffraction (XRD).
- the cellulose fine fibers are chemically modified at least on their surfaces.
- Cellulose fine fibers having at least the surface chemically modified have a length-weighted average fiber length of 110 ⁇ m or more and 500 ⁇ m or less of fibers having a fiber length of 100 ⁇ m or more as measured by an automatic fiber shape analyzer, and the fiber length is The number frequency of fibers having a fiber length of 411 ⁇ m or more may be 54% or less among the fibers having a length of 100 ⁇ m or more.
- the cellulose fine fibers chemically modified at least on the surface means cellulose fine fibers chemically modified at least part of the hydroxyl groups in the cellulose skeleton.
- Chemically modified cellulose microfibers are typically either chemically modified all the way from the surface to the interior, or have areas where the surface is chemically modified but not chemically modified. be.
- Cellulose microfibers according to one embodiment have chemically modified surfaces and areas that are not chemically modified.
- the crystal structure of the entire cellulose fine fibers does not change, and the crystal structure before chemical modification is maintained (for example, the cellulose fine fibers are subjected to XRD , it can be confirmed that it is a cellulose type I crystal structure).
- Such cellulose microfibers can be judged to be cellulose microfibers having chemically modified surfaces and areas that are not chemically modified.
- the cellulose microfibers have a cellulose Type I crystal structure.
- Cellulose fine fibers according to one aspect, in an automatic fiber shape analyzer, the following fiber shape parameters, (1) an average fiber diameter of 42.5 ⁇ m or less, (2) fine fiber area ratio is 90% or less, (3) Among the fibers with a fiber length of less than 100 ⁇ m, the number frequency of fibers having a fiber length of 20 ⁇ m or more and 56 ⁇ m or less is 30% or more and 97% or less, and (4) The fibrillation rate is 5% or less, is preferably satisfied.
- SEM scanning electron microscope
- the ratio of the total area occupied by ultrafine fibers having an area occupied by 15 ⁇ m 2 or less to the total area occupied by cellulose fine fibers is preferably 10% or more and 80% or less.
- a fiber length of 100 ⁇ m is defined as a threshold value for fiber parameters in measurement, and fibers with a fiber length of 100 ⁇ m or more are defined as normal fibers, and fibers with a fiber length of less than 100 ⁇ m are defined as fine fibers.
- Cellulose fine fibers are dispersed in pure water to prepare 1 L of aqueous dispersion.
- the solid content final concentration of the cellulose fine fibers is 0.003 to 0.005% by mass.
- the cellulose fine fiber before dilution is a water dispersion of less than 2% by mass, it may be simply mixed with a spatula or the like, but the water dispersion of 2% by mass or more, a water-containing cake or powder, etc.
- a high-shear homogenizer manufactured by IKA in one aspect, trade name "Ultra Turrax T18" is used to perform dispersion treatment under treatment conditions: rotation speed of 25,000 rpm for 5 minutes.
- Average fiber length Mean arithmetic length [ ⁇ m]
- Length-weighted average fiber length in normal fibers fibers with a fiber length of 100 ⁇ m or more
- Mean length-weighted Length [ ⁇ m] (3) Number frequency of fibers with a fiber length of 411 ⁇ m or more in normal fibers (fibers with a fiber length of 100 ⁇ m or more): Calculated from the length-weighted fiber length distribution ( ⁇ m) of normal fibers.
- Mean fiber diameter Mean fiber width [ ⁇ m]
- Fine fiber area ratio Fine content, % in Area
- Fibrillation rate MacroFibrillation index [%]
- the data interval can be set arbitrarily, so any setting can be made as long as the distribution of the fibers having the above-mentioned fiber length can be confirmed. .
- the cellulose fine fibers according to one aspect have an average fiber length of 110 ⁇ m or more and 500 ⁇ m or less, or 130 ⁇ m or more and 350 ⁇ m or less in an automatic fiber shape analyzer.
- the mean fiber length is the arithmetic mean fiber length (Mean Arithmetic fiber length), and means the length obtained by connecting the ends of the bent fiber with a straight line.
- the average fiber length of the cellulose fine fibers is preferably 150 ⁇ m or more and 250 ⁇ m or less, more preferably 160 ⁇ m or more and 200 ⁇ m or less.
- the cellulose fine fibers according to one aspect have a weighted average fiber length of 110 ⁇ m or more and 500 ⁇ m or less, more preferably 120 ⁇ m or more and 400 ⁇ m or less, as measured by an automatic fiber shape analyzer. More preferably, it is 130 ⁇ m or more and 350 ⁇ m or less.
- the length-weighted average fiber length is defined in ISO/FDIS 16065-2:2006 and is the average fiber length, for bent fibers, which corresponds to the actual fiber length taking into account the bending shape.
- the fiber length of the normal fiber when blended in the resin, the fibers that are too long can be uniformly dispersed without entangling with each other to form aggregates, and the stress transmission property is improved, so the strength is improved. , and the fracture strain increases.
- the number frequency of fibers with a fiber length of 411 ⁇ m or more among normal fibers is 54% or less, as measured by an automatic fiber shape analyzer.
- the number frequency can be calculated from the length-weighted fiber length distribution described above.
- the length-weighted fiber length is the fiber length that, in a bent fiber, corresponds to the actual fiber length taking into account its bent shape.
- the fiber length of the normal fiber is in this range, when blended in the resin, the fibers that are too long can be uniformly dispersed without entangling with each other to form aggregates, and stress transmission is improved. Fracture strain increases.
- the number frequency of fibers having a fiber length of 411 ⁇ m or more is preferably 40% or less, more preferably 30% or less.
- the lower limit is not particularly limited and is 0% or more.
- the cellulose fine fibers of the present embodiment preferably have an average fiber diameter in an automatic fiber shape analyzer of 42.5 ⁇ m or less, or 41.5 ⁇ m or less, or 40 ⁇ m or less, or 38 ⁇ m or less, or 35 ⁇ m or less, or 30 ⁇ m or less, Or it is 25 ⁇ m or less.
- an automatic fiber shape analyzer 42.5 ⁇ m or less, or 41.5 ⁇ m or less, or 40 ⁇ m or less, or 38 ⁇ m or less, or 35 ⁇ m or less, or 30 ⁇ m or less, Or it is 25 ⁇ m or less.
- a smaller fiber diameter is preferable because L/D is larger, but it may be 1.5 ⁇ m or more in view of the resolution of the measuring device. Moreover, from the viewpoint that a certain thickness or more is advantageous for increasing the flexural elasticity of the fiber-reinforced resin, the thickness is preferably 15 ⁇ m or more.
- the specific surface area In cellulose fine fibers, the specific surface area generally corresponds to the average fiber diameter in one aspect, and the smaller the average fiber diameter, the larger the specific surface area. In one aspect, the specific surface area is preferably 20 m 2 /g or more, or 30 m 2 /g or more, or 40 m 2 /g or more from the viewpoint of increasing the strength of the fiber reinforced resin, and increases the bending elasticity of the fiber reinforced resin. From the viewpoint, it is preferably 100 m 2 /g or less, 80 m 2 /g or less, or 60 m 2 /g or less.
- the average fiber diameter converted from the specific surface area by the procedure described in the [Example] section of the present disclosure is from the viewpoint of increasing the bending elasticity of the fiber reinforced resin.
- it is 20 nm or more, or 30 nm or more, and in one aspect, it is 150 nm or less, or 130 nm or less in that the strength of the fiber reinforced resin can be increased by entangling the cellulose fine fibers with each other in the resin. , or 100 nm or less.
- the cellulose fine fibers of the present embodiment preferably have a fine fiber area ratio of 90% or less, or 85% or less, or 80% or less, or 75% or less, or 60% or less, or 50% or less.
- the fine fiber area ratio is the ratio of the total area of observed images of fine fibers having a fiber length of less than 100 ⁇ m to the total area of observed images of all fibers (area of normal fibers + area of fine fibers). .
- the fine fiber area ratio is preferably 5% or more, or 10% or more, or 20% or more, or 30% or more.
- the number frequency of fibers having a fiber length of 20 ⁇ m or more and 56 ⁇ m or less among fine fibers (fibers having a fiber length of less than 100 ⁇ m) is preferably 97% or less in an automatic fiber shape analyzer. or 90% or less, or 85% or less, or 80% or less, or 75% or less, or 70% or less, or 65% or less. Since these fine fibers are too short in fiber length, they tend to have poor stress transmissibility and contribute little to improvement in strength. A particularly effective reinforcing effect can be obtained by controlling the number frequency of these fine fibers within a predetermined range.
- Fine fibers with a fiber length of 20 ⁇ m or more and 56 ⁇ m or less are not insignificantly generated with the refining treatment of the cellulose raw material, so in one aspect, the number frequency may be 5% or more, and in one aspect, 30%. or more, or 50% or more, or 55% or more, or 60% or more.
- the number frequency of fibers having a fiber length of 20 ⁇ m or more and 56 ⁇ m or less in fine fibers is within the above range, and at the same time, normal fibers (fibers with a fiber length of 100 ⁇ m or more) are included.
- the number frequency of fibers having a fiber length of 411 ⁇ m or more is 30% or less.
- a fiber having a fiber length of 411 ⁇ m or more is too long, so that it easily aggregates in the resin and contributes little to improving the elastic modulus. Therefore, it is effective to control the number frequency of fibers having a fiber length of 411 ⁇ m or more to be low, preferably 10% or less, more preferably 5% or less.
- the lower limit is not particularly limited, but since it is difficult to completely eliminate fibers having a fiber length of 411 ⁇ m or more, in one aspect, it may be 1% or more.
- the cellulose fine fibers of the present embodiment preferably have a fibrillation rate of 5% or less in an automatic fiber shape analyzer.
- the fibrillation rate refers to the ratio of n branched side chains L ( Sub) is the ratio of the total length and is defined by the following equation.
- the fibrillation rate of the cellulose fine fibers is preferably 4% or less, or 3% or less, or 2.5% or less, or 2% or less.
- the lower limit is not particularly limited, and in one aspect, it is 0% or more, or 0.01% or more, or 0.1% or more.
- the ratio of the total area occupied by the ultrafine fibers having an area occupied by 15 ⁇ m 2 or less to the total area occupied by the cellulose fine fibers, that is, the ratio of the area occupied by the ultrafine fibers is preferably 10% or more and 80% or less.
- These microfibers are fibers in a region that cannot be measured by an automatic fiber shape analyzer due to the resolution of the element.
- the occupied area ratio of the ultrafine fibers is more preferably 15% or more and 75% or less, more preferably 20% or more and 70% or less, and most preferably 20% or more and 65% or less.
- the cellulose fine fibers having the occupied area ratio of the ultrafine fibers within the above range may be fined using at least one type of physical technique, and are generally cellulose nanofibers, CNF, CeNF, It is called a fine cellulose fine fiber or the like.
- the occupied area ratio of microfibers is measured by the following procedure.
- An aqueous dispersion of cellulose fine fibers having a solid content concentration of 0.2 to 2% by mass is diluted with dimethyl sulfoxide (DMSO) to a solid content of 5 ppm by mass, and a homogenizer (in one aspect, manufactured by IKA, trade name "Ultra Turrax T18" ) at 3000 rpm for 30 seconds to form a DMSO dispersion.
- DMSO dimethyl sulfoxide
- a homogenizer in one aspect, manufactured by IKA, trade name "Ultra Turrax T18"
- An osmium plasma coating is applied to a smooth substrate (silicon wafer or glass substrate) and heated to 130° C. on a hot plate.
- 3. 7 ⁇ L of the DMSO dispersion liquid is dropped onto the center of the heated smooth substrate, and left to dry under heating to fix the cellulose fine fibers on the substrate. 4.
- the substrate on which the obtained cellulose fine fibers were fixed was observed with a scanning electron microscope (SEM) at an acceleration voltage of 1.5 kV, an observation magnification of 400 times, and a resolution of 400 pixels or more per 100 ⁇ m. Take an image. 5. The number of pixels corresponding to the threshold value of 15 ⁇ m 2 is calculated from the number of pixels on the scale bar of the SEM image. 6. A binarized image is created from the acquired SEM image by the MaxEntropy method using image processing software ImageJ. 7. The binarized image is subjected to particle analysis using ImageJ's Analyze Particle, and the area (pixel) of the single fiber of the cellulose fine fiber is calculated. 8.
- SEM scanning electron microscope
- the particle analysis results of the four captured images are totaled, two pixels or less are deleted as noise, and the area of less than 15 ⁇ m 2 is defined as ultrafine fibers as a threshold, and the area of ultrafine fibers of less than 15 ⁇ m 2 in the total area of cellulose fine fibers.
- the peculiar fiber shape of the cellulose fine fibers of the present embodiment more specifically, in one aspect, the length-weighted fiber length of the normal fiber, the average fiber length, the average fiber diameter, the fine fiber area ratio, the fine fiber fiber length, A fiber shape such that the fibrillation ratio and/or the occupied area ratio of ultrafine fibers are within the range of the present embodiment, or in one aspect, the average fiber length, average fiber diameter, and area ratio of fine fibers (microfiber fiber occupied area ratio), the number frequency of fibers with a fiber length of 20 ⁇ m or more and 56 ⁇ m or less among the fibers with a fiber length of less than 100 ⁇ m, the number frequency of fibers with a fiber length of 411 ⁇ m or more among the fibers with a fiber length of 100 ⁇ m or more, and As a method for realizing a fiber shape in which the fibrillation ratio is within the scope of the present embodiment, for example, one or more of the techniques exemplified below may
- the raw material for 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 possible to use cellulose raw materials with high 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. preferable.
- the cellulose microfibers are of plant origin.
- the cellulose raw material has an average fiber length (specifically, a length-weighted average fiber length) of 3 mm or less and/or a number ratio of fibers having a fiber length of 3 mm or more in an automatic fiber shape analyzer. is 20% or less.
- the fibrillation process e.g., beating using a disc refiner or a high-pressure homogenizer, etc.
- energy transfer in the beating section is improved, and clogging is prevented. Since it is less likely to occur, a stable defibration treatment can be achieved even when the concentration of cellulose is relatively high.
- the average fiber length is more preferably 2.5 mm or less, still more preferably 2.0 mm or less, and particularly preferably 1.6 mm or less. Since the above effect increases as the average fiber length decreases, the lower limit is not particularly limited, but considering the mechanical properties when using the cellulose fine fibers after beating treatment as a resin filler, it is preferably 0.1 mm or more, and 0.1 mm or more. 5 mm or more is more preferable.
- the number ratio of fibers having a fiber length of 3 mm or more is more preferably 15% or less, and still more preferably 10% or less.
- the lower limit is not particularly limited, it is preferably 0.5% or more, and more preferably 1% or more, as a range that can be obtained in a realistic pretreatment.
- the fiber length of the cellulose raw material described above can be measured using a fiber shape automatic analyzer (Morfi Neo manufactured by Techpap). The measurement procedure is described below.
- a 1 L water dispersion is prepared by dispersing the cellulose raw material in pure water.
- the solid content final concentration of the cellulose raw material is 0.003 to 0.005% by mass.
- the cellulose raw material before dilution is a water dispersion of less than 2% by mass, it may be simply mixed with a spatula or the like, but a water dispersion of 2% by mass or more, a water-containing cake or powder, etc. may be used.
- dispersion treatment is performed using a high-shear homogenizer (manufactured by IKA, trade name "Ultra Turrax T18”) under treatment conditions: 25,000 rpm for 5 minutes.
- the water dispersion prepared above is subjected to an autosampler and measured.
- the obtained measurement results are output in txt format (or csv format), and each shape parameter is extracted or calculated from the measurement results.
- txt format or csv format
- each shape parameter is extracted or calculated from the measurement results.
- the following values among the measurement results shall be used.
- Length-weighted average fiber length Mean length-weighted Length [ ⁇ m]
- the cellulose raw material of the present embodiment is subjected to one or more pretreatments selected from pulverization, grinding, and classification, and then defibrated (for example, beating). may be used.
- the pretreatment according to one aspect is performed from a cellulose raw material having an average fiber length of more than 3 mm and a number ratio of fibers having a fiber length of 3 mm or more is more than 20%, and the average fiber length is 3 mm or less and / or This is a treatment to produce a pretreated cellulose raw material in which the number percentage of fibers of 3 mm or more is 20% or less.
- the pulverization process of the present embodiment is a process of dry pulverizing the cellulose raw material, and as a pulverizer, a coarse pulverizer, an intermediate pulverizer, a fine pulverizer, or the like can be used.
- Coarse crushers include jaw crushers (i.e., crushers that crush raw materials between a fixed plate and a movable plate and crush them with strong compressive force), gyratory crushers (i.e., fixed cone cavities and eccentric rotary motion).
- a crusher that bites the raw material between the mantle and crushes it by compressive force an impact crusher (that is, impact crushers attached to a cylindrical rotor that rotates at high speed crush the raw material by impact, and the raw material is further crushed by a repulsion plate.
- pulverizer that impact pulverizes by hitting at high speed) and the like.
- a roll crusher that is, a crusher in which a plurality of cylindrical horizontal rolls are installed, a raw material is passed through the gap between these rolls, and crushed by the pressure of two rolls with different rotation directions and rotation speeds
- edge Runners i.e. pulverizers that crush, mix and knead raw materials by rolling two heavy rollers of large diameter on horizontal discs for compaction and shearing
- disintegrators i.e. steel A pulverizer that rotates two cage-type rotors made of steel in opposite directions around a concentric shaft and applies impact force by centrifugal force and rotational action to the raw material supplied from the inner rotor to pulverize it. Grinding mill, quasi-autogenous grinding) mill, autogenous grinding mill, etc.
- a SAG mill is a grinder that uses both large stones and metal balls for grinding. SAG mills typically use the smallest balls with 6-15% charge. As the drum rotates, the large stones and iron balls inside are thrown up, colliding with objects and crushed. At this time, they are further reduced in particle size by friction.
- the SAG mill is characterized by its large diameter and short cylinder length, and plates are arranged inside the mill for mixing objects.
- fine pulverizers examples include screen-type (screen mills), rotating disk-type, axial flow-type, and ball-mill-type pulverizers, rod mills, and jet mills.
- sand or metal balls are usually packed inside a cylinder that rotates horizontally or slightly inclined, and crushing is performed by collision and friction with the balls. Material to be ground is supplied from one side of the cylinder and the ground product is discharged from the other side.
- a rod mill has almost the same structure as a ball mill, but uses rods (metal cylinders) instead of balls as grinding media.
- the object to be pulverized is pulverized by the impact of the rod on the rotating drum (body). Compared to ball milling, over-grinding is less likely and a milled product with a relatively uniform particle size can be obtained.
- jet mill compressed air is used to generate supersonic airflow to pulverize the material to be pulverized.
- jet mills There are two types of jet mills: the pancake type, in which jet nozzles are arranged in a spiral pattern, and the impingement type, in which supersonic airflow from jet nozzles is jetted onto an impingement plate.
- an intermediate pulverizer or a fine pulverizer is preferable, and a fine pulverizer is more preferable, for the treatment of the cellulose raw material in this embodiment.
- fine pulverizers the screen type is preferable because of its excellent processing capacity.
- the grinding treatment of the present embodiment is a treatment in which a cellulose raw material is dispersed in an aqueous medium and the aqueous dispersion is subjected to a pulverization treatment.
- aqueous media include water itself, monohydric alcohols such as ethanol, n-propanol, isopropanol and butanol, polyhydric alcohols such as ethylene glycol, diethylene glycol and glycerin, ketones such as acetone, and nitriles such as acetonitrile.
- a mixed medium of water and an organic solvent which is one or more of solvents, pyrrolidone-based solvents, and the like, can be mentioned.
- 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.
- Grinding machines that can be used in this embodiment include a rotary stone mill, a grinding machine, a planetary mixer, a single-screw extruder, a twin-screw extruder, and a bead mill.
- a bead mill is a medium agitating pulverizer that uses beads to nano-disperse or finely pulverize powder.
- the object to be processed and beads (media) are placed in the crushing chamber (vessel), and the stirring mechanism rotates at high speed to give energy to the beads by centrifugal force, and the crushed particles are subjected to shear stress, shear stress, friction force, and Shatter by impact force.
- the cellulose concentration in the aqueous dispersion used for grinding is preferably 50% by mass or less, more preferably 25% by mass or less, and particularly preferably 20% by mass or less.
- the lower limit is preferably 1% by mass or more, more preferably 2% by mass or more, still more preferably 5% by mass or more, and particularly preferably 10% by mass or more, in consideration of grinding efficiency.
- the classification treatment of the present embodiment is an operation of dividing the cellulose raw material according to the fiber length for the purpose of aligning the fiber length, and either dry classification or wet classification can be used.
- dry classification include gravity field classification, inertial force field classification, and centrifugal force field classification (natural vortex type or forced vortex type).
- wet classification includes gravity field classification and centrifugal force field classification (free vortex type). ), and centrifugal field classification (forced vortex type), both of which can be used.
- Classification using meshes such as sieves, screens, wires (edge wires) and nets, and classification by centrifugation can also be used.
- Classification using a mesh opening is preferable in consideration of production efficiency, and among them, it is more preferable to use a dry cyclone or screen, or a wet screen or edge wire, and it is even more preferable to use a wet screen or edge wire. It is particularly preferred to use wet edge wires.
- the glucose content of the cellulose raw material and/or the cellulose fine fibers according to the analysis of the constituent sugars of the present embodiment is preferably 80% by mass or more.
- the cellulose fiber raw material for producing cellulose fine fibers also preferably has a glucose content of 80% by mass or more as determined by constituent sugar analysis. Their glucose content is more preferably 85% by mass or more, or 90% by mass or more, or 91% by mass or more, or 93% by mass or more.
- the glucose content is 99.5% by mass due to the limit of impurities (for example, oil and fat components other than polysaccharides, various contaminant components, etc.) that can be mixed in during the harvesting and refining process of cellulose raw materials, or in the manufacturing process of cellulose fine fibers. or less, or preferably 99% by mass or less.
- impurities for example, oil and fat components other than polysaccharides, various contaminant components, etc.
- the fact that the cellulose fine fibers have a high glucose content usually means that the cellulose purity is high. means less quantity.
- the method for measuring the glucose content in constituent sugar analysis is as follows. Constituent sugar analysis was performed according to the US Department of Energy's National Renewable Energy Laboratory analytical procedure (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 is added to 200 mg of the sample to swell it at 30° C. for 1 hour.
- a suitable example of cellulose raw material is refined cellulose fiber.
- Purified cellulose fibers are softwood chips, hardwood chips, or non-wood cellulose raw materials (derived from cotton, hemp, bagasse, kenaf, bamboo, straw, seaweed, algae, sea squirt, bacterial cellulose, etc.). from, means a purified cellulose raw material, such as refined pulp or fluff, obtained through delignification by digestion, and refining and bleaching steps aimed at removing hemicellulose.
- cotton fibers, cotton linters, and cellulose raw materials derived from bacteria are particularly preferable because of their high cellulose purity.
- cut yarn of regenerated cellulose fibers can also be used as a raw material for cellulose fine fibers
- cut yarn of regenerated cellulose obtained by an electrospinning method can also be used as a raw material for refined cellulose fibers of cellulose fine fibers.
- appropriate refining conditions cooking temperature, alkali concentration during cooking, bleaching agent concentration and bleaching time
- refined cellulose fibers with high cellulose purity are produced. It is preferably produced and used as a raw material.
- recycled cotton refers to fibers that are made by collecting and crushing cutting waste and fallen cotton discarded at spinning factories and sewing factories, and crushing cotton that has been prepared into the form of cloth, clothing, etc. It refers to fibers etc. obtained by Recycled wood refers to wood left over from sawmills, wood generated from construction, wood left over from thinning, wood left over from forestry, etc., which is chipped and then pulped by a conventional method.
- recycled cotton is preferable as the cellulose raw material.
- the cellulose fiber or the above-mentioned purified cellulose fiber is further impregnated in water and heat-treated at a temperature of 100 ° C. or higher, and the cellulose fiber or the above-mentioned purified cellulose fiber is treated with a strong alkaline aqueous solution such as sodium hydroxide (alkali concentration: 1% by mass to 10% by mass), left to stand or stirred for a certain period of time in the range of 0 ° C. to 60 ° C., and then repeatedly washed with water.
- a strong alkaline aqueous solution such as sodium hydroxide (alkali concentration: 1% by mass to 10% by mass)
- Enzymatic treatment in which hemicellulose-degrading enzymes such as xylase and mannanase or cellulase is allowed to act at a temperature in the range of 35°C to 55°C by impregnation in water, or a combination of a plurality of the above three treatments may be used for purification. It may be effective for obtaining purified cellulose fibers of high purity. These treatments not only reduce the load of microfibrillation, but also remove impurities such as lignin and hemicellulose existing on the surface and interstices of the microfibrils that make up the cellulose fibers into the aqueous phase. Since it also has the effect of increasing the cellulose purity of the fiber, it can be very effective.
- water-soluble polysaccharide components produced at the same time as bacterial cellulose can be removed by washing with cold water in the range of 2°C to 10°C, which is effective as a purification method. Sometimes there is.
- the cellulosic feedstock and/or cellulosic fine fibers may have a cellulose type I crystal structure, or may have a cellulose type II crystal structure.
- the cellulose microfibers have a cellulose type I crystal structure.
- the crystallinity of the cellulose raw material or cellulose fine fibers of the present embodiment is preferably 55% or more, or 60% or more. When the degree of crystallinity is within this range, the mechanical properties (especially the strength and dimensional stability) of the cellulose fine fibers themselves are enhanced, so that the strength and dimensional stability of the fiber-reinforced resin obtained by dispersing the cellulose fine fibers in the resin are high.
- the crystallinity of the cellulose raw material or cellulose fine fibers is preferably 65% or more, more preferably 70% or more, and most preferably 80% or more.
- Alkali-soluble polysaccharides such as hemicellulose and acid-insoluble components such as lignin are present between microfibrils of plant-derived cellulose and between microfibril bundles.
- Hemicellulose is a polysaccharide composed of sugars such as mannan and xylan, and plays a role of connecting microfibrils by forming hydrogen bonds with cellulose.
- Lignin is a compound having an aromatic ring and is known to covalently bond with hemicellulose in plant cell walls. If the residual amount of impurities such as lignin in the cellulose fine fibers is large, discoloration may occur due to heat during processing. It is desirable that the crystallinity of the fine fibers be within the above range.
- cellulose raw material or cellulose fine fibers of the present disclosure have relatively high structural mobility, and by dispersing the cellulose fine fibers in the resin, the linear expansion coefficient is lower, and the strength and elongation during tensile and bending deformation are high. Since a more excellent resin composition can be obtained, one containing cellulose type I crystals or cellulose type II crystals is preferable, and one containing cellulose type I crystals and having a degree of crystallinity of 55% or more is more preferable.
- the cellulose fine fibers of the present embodiment are cellulose fine fibers in which the hydroxyl groups on the surface of the cellulose fine fibers are modified by chemical modification, and are chemically modified in a state before defibration (in one aspect, a pulp state), and then refined as described later.
- the treatment may be carried out, or the cellulose fine fibers may be chemically modified after being subjected to a refining treatment.
- it is preferable to chemically modify the fiber before defibration, and then to perform the fibrillation treatment described below.
- this chemical modification can be performed before pretreatment, but it is easier to perform this chemical modification after pretreatment, which is preferable.
- Examples of chemical modification methods include esterification, etherification, and urethanization, but esterification is preferred. Among them, saturated monocarboxylic acid esterification such as acetic acid esterification (acetylation), propionate esterification, pentanoic acid (valeric acid) esterification, and hexanoic acid (caproic acid) esterification is preferable. ) Acetate esterification (acetylation) is preferable from the viewpoint of the heat resistance of the cellulose fine fibers after the treatment, but esterification using a dicarboxylic acid such as phthalate esterification may also be used. For chemical modification, a general esterification reaction method using a saturated carboxylic acid or its acid anhydride or acid chloride, saturated vinyl acetate, vinyl monocarboxylate such as vinyl propionate, or the like can be used.
- solvent that swells the cellulose raw material well in order to chemically modify the fiber surface inside the cellulose raw material.
- Solvents that swell the cellulosic material well are, in one aspect, aprotic polar solvents such as dimethylsulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), N , N-dimethylacetamide (DMAc), or any mixture thereof.
- the cellulose fine fibers are concentrated by suction filtration or the like to form a wet cake, then diluted and dispersed in a solvent for chemical modification.
- the chemical modification method may be the same as the chemical modification of the cellulose raw material.
- the cellulose solid content concentration is preferably 30% by mass or less, more preferably 20% by mass or less.
- the esterification agent since the esterification agent also reacts with water, it is better to bring in less moisture, and the lower limit of the cellulose solid content concentration is more preferably 5% by mass or more, or 10% by mass or more. .
- the degree of substitution (DS) degree of acylation, for example, degree of acetylation
- the degree of substitution (DS) degree of acylation, for example, degree of acetylation
- the upper limit is preferably 1.3 or less, since if the DS is too high, the crystallinity tends to decrease, and the mechanical properties of the resin composition obtained by combining the cellulose fine fibers and the resin tend to decrease. It is preferably 1.1 or less, more preferably 1.0 or less.
- the degree of acyl substitution can be calculated from the reflection infrared absorption spectrum of the esterified cellulose fine 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 C ⁇ O absorption band based on the acyl group appears at 1730 cm ⁇ 1
- the peak of the C—O absorption band based on the cellulose skeleton appears at 1030 cm ⁇ 1 (see FIG. 1).
- Create a correlation graph with the modification rate (IR index 1030) defined by the ratio of peak intensity, calibration curve degree of substitution calculated from the correlation graph DS 4.13 ⁇ IR index (1030) can be obtained by using
- the conditions for the 13 C solid-state NMR measurement to be used are, for example, as follows. Apparatus: Bruker Biospin Avance500WB Frequency: 125.77MHz Measurement method: DD/MAS method Waiting time: 75 sec NMR sample tube: 4mm ⁇ Accumulated times: 640 times (about 14 hours) MAS: 14,500Hz Chemical shift reference: glycine (external reference: 176.03 ppm)
- the cellulose fibers in one aspect, can be surface-chemically modified cellulose microfibers.
- the DS heterogeneity ratio (DSs/DS) defined as the ratio of the degree of substitution (DSs) on the fiber surface to the degree of substitution (DS) of the entire fiber of the chemically modified cellulose fine fiber is 1.05 or more. be.
- the DS heterogeneity ratio (DSs/DS) defined as the ratio of the degree of acyl substitution (DSs) on the surface of the fiber to the degree of acyl substitution (DS) on the entire fiber is preferably 1.05. That's it.
- the larger the value of the DS heterogeneity ratio the more the heterogeneous structure like a sheath-core structure (that is, the fiber surface layer is highly chemically modified, while the core of the fiber retains the original unmodified cellulose structure. Structure) is remarkable, and while having high tensile strength and dimensional stability derived from cellulose, it is possible to improve affinity with resin when composited with resin and improve dimensional stability of the resin composition. be.
- 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, preferably 30 or less, or 20 or less, or 10 or less, or 6 or less, or 4 or less, or 3 or less.
- DS s varies depending on 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, 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.
- DSs is obtained by the following method. That is, esterified cellulose fine fibers pulverized by freeze-grinding are placed on a 2.5 mm ⁇ dish-shaped sample stage, the surface is flattened by pressing down, and measurement is performed by X-ray photoelectron spectroscopy (XPS).
- XPS X-ray photoelectron spectroscopy
- Average fiber length after modification (nm)/average fiber length before modification (nm) x 100) is preferably 70% or more, more preferably 80% or more, and particularly 90% or more. preferable.
- the average fiber length referred to here is the length-weighted average fiber length measured using a fiber shape automatic analyzer (Morfi Neo manufactured by Techpap).
- Cellulose fine fibers can be obtained by pulverizing the raw materials as described above.
- a refining device such as a beater, disc refiner, high-pressure homogenizer, water jet, disc mill, ball mill, bead mill, mass colloider, homomixer, etc. miniaturization using
- the refinement may be a beating process.
- the miniaturization process may be performed in one step (processing with one type of blade) or in multiple steps (processing with multiple types of blades). Different devices may be used in combination. In one aspect, multiple stages are preferred.
- the pulp is first chemically modified and then refined, so the hydrophilicity of the pulp is reduced, so the peripheral speed is set to, for example, 10 m/s or more, preferably 20 m/s or more, more preferably 25 m/s. /s or more, for example, 90 m/s or less, preferably 80 m/s or less, more preferably 50 m/s or less, by a mixer such as a homomixer.
- a mixer such as a homomixer.
- uniform fine cellulose fine fibers can be obtained by uniform fine processing.
- it may be effective to use high-purity water such as distilled water or ion-exchanged water as the water used at this time.
- multi-step miniaturization When cellulose is micronized in multiple stages, it is effective to combine micronization mechanisms or two or more types of micronization devices with different shear rates.
- a method for multi-stage refinement it is preferable to carry out multi-stage refinement using disc refiners having different disc configurations, or to perform refinement by a high-pressure homogenizer after refinement by a disc refiner.
- any of a single disc refiner, a double disc refiner, and a conical refiner may be used as the disc refiner.
- a single disc refiner with high clearance controllability between the fixed blade and the rotary blade is preferred in order to control refinement to a high degree.
- pulp or cotton-like cellulose fibers e.g., purified cellulose fibers
- pulp or cotton-like cellulose fibers are added to an aqueous medium at, for example, 0.5% by mass or more and 6% by mass or less, preferably 0.8% by mass or more.
- the water used at this time it may be effective to use high-purity water such as distilled water or ion-exchanged water.
- defibration may be performed in a continuous circulation process in which the slurry stored in the tank is returned to the original tank via the disc refiner. are prepared (tanks A and tanks B), the slurry is first sent from tank A into tank B through a disc refiner and stored, and when the slurry in tank A has been treated, continuously Switching to the process of transferring liquid from tank B to tank A through the disc refiner and accumulating it, and thereafter performing the fibrillation process in a continuous process in which these processes are alternately repeated, the slurry is reliably discharged in each disc refiner process. Since the slurry is passed through, it is possible to apply a uniform number of passes to the entire amount of the slurry, which is more preferable from the viewpoint of the uniformity of defibration, that is, the quality stability of the cellulose fine fibers.
- FIG. 2 is a diagram for explaining an arrangement example of blades and grooves of a disc refiner
- FIG. 3 is a diagram for explaining blade widths, groove widths, and inter-blade distances of a disc refiner.
- the number of blades may be one or two or more, but it is preferable to use a refiner having at least two different blades. Referring to FIGS. 2 and 3, as a specific configuration of the blade, in the disc refiner having the blade 11 and the groove 12 as shown in FIG. It is important to appropriately adjust the value obtained by dividing the width W B by the groove width W G (hereinafter referred to as the blade groove ratio).
- a refiner with a blade width of 1.5 mm or more and 5 mm or less and a blade groove ratio of 0.1 or more and 1.0 or less After performing refining treatment (hereinafter referred to as the former stage), the blade It is particularly preferable to perform the refinement treatment (hereinafter referred to as the latter stage) with a refiner having blades with a 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.
- cellulose fine fibers with less fuzz can be obtained.
- the generation of fibers having a fiber length of 20 ⁇ m or more and 56 ⁇ m or less, which has a poor reinforcing effect, can be suppressed.
- Another miniaturization step may be added between the former stage and the latter stage.
- the blade width is 0.1 mm or more and 1.0 mm or less
- the blade groove ratio is 0.5 or more and 1.0 or less. It is particularly preferred to perform microprocessing in a refiner having a At that time, the fiber length of the raw material to be used is preferably 500 ⁇ m or more, more preferably 700 ⁇ m or more, more preferably 700 ⁇ m or more, as measured by the length-weighted average fiber length of the above-mentioned automatic fiber shape analyzer (Morfi Neo manufactured by Techpap in one aspect).
- ⁇ m or more is 900 ⁇ m or more, preferably 3000 ⁇ m or less, more preferably 2000 ⁇ m or less, more preferably 1500 ⁇ m or less, and even more preferably 1300 ⁇ m or less.
- the distance WL distance between two blades (specifically, the rotary blade 21 and the fixed blade 22 in FIG. 3) (hereinafter simply referred to as It is advantageous to control the blade distance).
- the distance between the blades it is possible to control the fiber length of the cellulose fine fibers and the degree of beating.
- the distance between the blades is 0.05 mm or more and 0.5 mm or less in the former processing, and that the distance between the blades is 0.05 mm or more and 0.3 mm or less in the latter processing.
- the distance between blades when processing in one step, it is preferable to set the distance between blades to 0.05 mm or more and 0.3 mm or less.
- the distance between the fixed blade and the rotary blade in the cellulose refining process with a disc refiner is advantageous for producing cellulose fine fibers that are homogeneous and have good mechanical properties as a filler.
- the distance between the blades of conventionally used single disc refiners is adjusted by using a screw type screw jack or the like, so there is play in the runner portion that fixes the rotary blades. Therefore, if the runner is strongly pulled in the thrust direction, it will move by about 0.3 mm. Therefore, it is preferable that the amount of movement (play) is small in order to obtain finely divided cellulose with good accuracy and reproducibility. It is more preferable to make it 0.05 mm or less.
- the accuracy of closing the gap between the blades is 5 ⁇ m or less, and the gap between the blades can be finely closed, more preferably 3 ⁇ m or less, and most preferably 1 ⁇ m or less.
- a single disc refiner having a movement amount in the trust direction of 0.03 mm may be used by using a ball screw type jack as the blade distance adjusting mechanism.
- a speed reducer to the ball screw jack so that the distance between the blades can be finely adjusted.
- the distance between blades is adjusted to a ball screw type jack, so that the single disc refiner with a movement amount in the trust direction of 0.03 mm is used, and the ball screw type jack A reduction gear is attached to the blade, and an example using a device that can finely adjust the distance between blades in increments of 1 ⁇ m is shown. Any mechanism may be used as long as it provides
- the degree of refinement can also be controlled by the number of times the cellulose fine fibers pass through the disk portion, ie, between the rotary blade and the fixed blade (hereinafter referred to as the number of passes).
- the number of passes means the number of times that the refiner treatment is performed after the distance between the blades is reduced to the target distance between the blades (that is, the number of passes between the rotating field and the fixed field).
- the number of passes of the disc refiner is preferably 5 times or more, more preferably 20 times or more, and still more preferably 40 times or more. As the number of passes is increased, the distribution of the fiber shape gradually converges to a constant value, so the higher the number, the better. However, considering the productivity, the upper limit of the number of passes is preferably 300 or less.
- the shape of the cellulose fine fibers obtained by the disc refiner treatment is controlled by the combined effects of the configuration of the disc refiner (the type and number of blades), the distance between the blades, the number of passes, the concentration, and the like.
- the strength of the treatment is determined by the configuration of the blades of the disc refiner and the distance between the blades.
- the processing strength will decrease, and if it is small, the processing strength will increase.
- the distance between blades is large, the processing strength will decrease, and if it is small, the processing strength will increase. Therefore, it is preferable to increase the distance between the blades when forming blades with high processing strength, and conversely, when forming blades with low processing strength, it is preferable to decrease the distance between blades. More preferably, it is a method of increasing the distance between blades with a configuration of blades with high processing strength, and by setting the number of passes as described above under this processing condition, it is possible to control the average fiber length and the distribution of the fiber length within a preferable range. is.
- Viscous beating is a beating method in which fibers tend to fluff and become finer, and beating method in which fibers tend to be cut in the longitudinal direction is called free beating.
- the blade configuration of the disc refiner the number of blades is large, the blade length is long, the ratio of the blade width to the groove width (the blade groove ratio) is large, and the contact angle is large. increases, the force applied to the fibers at one intersection is dispersed, and the number of impacts on the fibers increases, resulting in a sticky beating tendency.
- the distance between the blades of the disc refiner is preferably widened when using blades that exhibit a tendency to free beating, and it is preferable to reduce the distance between blades when using blades that exhibit a tendency to be viscous beating, but the distance between blades is too narrow. It is preferable that the distance between the blades is 0.05 mm or more because clogging and short fibers due to cutting in the fiber length direction and excessive miniaturization occur.
- the fiber shape such as the average fiber diameter and fiber length distribution can be obtained.
- the fiber shape can be controlled within a preferred range.
- Method of controlling the number of passes in disc refiner processing As a method for controlling the number of passes, one tank is used for one refiner, the slurry is simply circulated, and the number of passes is controlled based on the flow rate, or one refiner Alternatively, two tanks may be used, and the slurry may be refined while reciprocating between the tanks. In the former, the equipment can be simplified. On the other hand, in the latter method, the cellulose fine fibers reliably pass through the disc portion in each treatment, so cellulose fine fibers with higher uniformity can be obtained. The latter method is preferable from the viewpoint of stably obtaining the cellulose fine fibers of the present embodiment, which have a good reinforcing effect on the resin, that is, the cellulose fine fibers having a uniform fiber shape.
- the cellulose fine fibers that have been refined by the disc refiner are further subjected to a refinement treatment by a high-pressure homogenizer.
- High-pressure homogenizers are more effective in making fibers thinner than disc refiners.
- Elongated cellulose fine fibers can be obtained by combining a disc refiner and a high pressure homogenizer.
- the high-pressure homogenizer treatment is performed at a pressure of preferably 30 MPa or higher, more preferably 50 MPa or higher, and more preferably 80 MPa or higher.
- the upper limit of the pressure may be preferably 300 MPa or less, more preferably 250 MPa or less, and more preferably 150 MPa or less in view of the characteristics of the apparatus.
- High-pressure homogenizers include the NS-type high-pressure homogenizer of Niro Soavi (Italy), the Rannie type (R model) pressure-type homogenizer of SMT Co., Ltd., the high-pressure homogenizer of Sanwa Machinery Co., Ltd., etc., and the ultra-high-pressure homogenizer , Mizuho Kogyo Co., Ltd. Microfluidizer, Yoshida Kikai Kogyo Co., Ltd. Nanomizer, Sugino Machine Co., Ltd. Ultimizer. Any device other than these may be used as long as it implements miniaturization with a similar mechanism.
- defibration treatment may be performed in a circulating continuous treatment process in which the slurry stored in the tank is returned to the original tank via the high-pressure homogenizer, but the high-pressure homogenizer is not used.
- Two tanks connected by pipes are prepared (tank A and tank B), and the slurry is first sent from tank A into tank B through a high-pressure homogenizer and stored, and the slurry in tank A is processed.
- the liquid is continuously transferred from tank B to tank A through a high-pressure homogenizer and accumulated. Since the slurry passes through the high-pressure homogenizer reliably every time, the entire amount of the slurry can be subjected to a uniform number of passes. more preferred.
- a pretreatment step may be performed prior to the miniaturization process.
- pretreatment methods include autoclave treatment under water immersion at a temperature of 100 to 150° C., enzyme treatment, immersion in an aqueous sodium hydroxide solution, or a combination thereof. All of these pretreatments have the effect of destroying the hydrogen bonds between cellulose microfibrils and not only reduce the load of the microfibrillation process, , Impurity components such as hemicellulose are discharged into the aqueous phase, and as a result, there is also the effect of increasing the ⁇ -cellulose purity of the finely divided fibers, so it may be effective in improving the heat resistance of cellulose fine fibers.
- the cellulose fine fibers of the present embodiment can be obtained as a wet compact (wet cake) by dehydrating the slurry using a filter or a paper machine.
- the papermaking method using a paper machine is advantageous in reducing drying shrinkage between cellulose fine fibers.
- dewatering is accomplished by filtering the slurry over a porous substrate.
- any paper machine with mesh size wires that dewater the slurry and retain the cellulosic fines can be used.
- a paper machine such as an inclined wire paper machine, a Fourdrinier paper machine, or a cylinder paper machine can be used.
- Cellulose fine fibers can also be used as a dry filler.
- drying can be performed using a known drying device such as a hot air dryer or a spray dryer.
- a dispersant because cellulose tends to aggregate during the drying process and is difficult to redisperse thereafter. By enhancing the redispersibility, the mechanical properties and stability of the obtained resin composition can be improved. It is desirable to add a dispersant to the cellulose fine fiber aqueous dispersion and then dry it while applying shear to obtain a cellulose powder.
- the dispersant can be at least one selected from the group consisting of surfactants, organic compounds having a boiling point of 100°C or higher, and resins having a chemical structure capable of highly dispersing cellulose.
- the surfactant should have a chemical structure in which a site with a hydrophilic substituent and a site with a hydrophobic substituent are covalently bonded.
- a site with a hydrophilic substituent and a site with a hydrophobic substituent are covalently bonded.
- those used in various applications such as food and industrial use can be used. For example, one or more of the following can be used.
- anionic surfactants any of anionic surfactants, nonionic surfactants, zwitterionic surfactants, and cationic surfactants can be used as surfactants, but the affinity with cellulose Anionic surfactants and nonionic surfactants are preferred, and nonionic surfactants are more preferred.
- surfactants having a polyoxyethylene chain, a carboxyl group, or a hydroxyl group as hydrophilic groups are preferable in terms of affinity with cellulose, and polyoxyethylene-based surfactants having a polyoxyethylene chain as a hydrophilic group.
- polyoxyethylene derivative is more preferred, and a nonionic polyoxyethylene derivative is even more preferred.
- the polyoxyethylene chain length of the polyoxyethylene derivative is preferably 3 or more, more preferably 5 or more, still 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 balance with coatability, the upper limit is preferably 60 or less, more preferably 50 or less, further preferably 40 or less, and particularly preferably 30 or less. 20 or less is most preferred.
- alkyl ether type alkylphenyl ether type, rosin ester type, bisphenol A type, ⁇ naphthyl type, styrenated phenyl type, and hydrogenated castor oil type are particularly suitable as hydrophobic groups because of their affinity with resins. is high, it can be preferably used.
- a preferable alkyl chain length (the number of carbon atoms excluding the phenyl group in the case of alkylphenyl) is preferably 5 or more, more preferably 10 or more, still more preferably 12 or more, and particularly preferably 16 or more. The greater the number of carbon atoms in the alkyl chain length, the higher the compatibility with common resins.
- the resin is polyolefin
- hydrophobic groups those having a cyclic structure or those having a bulky multifunctional structure are preferred.
- Those having a cyclic structure are preferably alkylphenyl ether type, rosin ester type, bisphenol A type, ⁇ -naphthyl type, and styrenated phenyl type, and those having a polyfunctional structure are preferably hydrogenated castor oil types.
- rosin ester type and hydrogenated castor oil type are particularly preferred.
- an organic compound with a boiling point of 100°C or higher may be effective as a non-surfactant-based dispersant.
- organic compounds include polyethylene glycol, polypropylene glycol, organic compounds having a glycerin structure, and the like.
- a high-boiling organic solvent such as liquid paraffin or decalin is effective.
- the resin is a polar resin such as nylon and polyacetate, it may be effective to use a solvent similar to the aprotic solvent that can be used in producing cellulose fine fibers, such as dimethyl sulfoxide. be.
- the reciprocal of the yield strain, 1/ ⁇ is preferably 200 or more in strain dispersion measurement of an aqueous dispersion with a cellulose concentration of 0.75% by mass. 250 or more is more preferable. If this parameter is within this range, the effect of improving the dynamic viscoelasticity at high temperatures is large when the cellulose fine fibers are added to the resin, that is, the storage elastic modulus increases at high temperatures.
- Cellulose fine fibers are said to form a pseudo-crosslinked structure in water due to entanglement between fibers and hydrogen bonding acting between cellulose molecules.
- Measurement condition Measuring instrument: Rheometer HAAKE MERS (manufactured by Thermo Fisher Scientific) Measuring jig: coaxial double cylinder (cup: CCB25 DIN, rotor: CC25 DIN Ti) Measurement mode: Oscillation Control method: Stress control Control range: 0.01 to 100 Pa Temperature: 25°C
- Cellulose fine fibers are dispersed in pure water.
- the solid content final concentration of the cellulose fine fibers is 0.75% by mass.
- dispersion treatment is performed by shaking in a sealed container with a filling rate of 75% by volume or less.
- a high shear homogenizer in one aspect, manufactured by IKA, trade name "Ultra Turrax T18" is used. Processing conditions: number of rotations Dispersion treatment is performed at 25,000 rpm for 5 minutes.
- a jig is attached to the rheometer, and 17.0 ⁇ 1.0 g of a cellulose fine fiber aqueous dispersion is charged using a pipette or dropper. 4. Measurement is performed based on the setting, and the reciprocal of the yield strain (1/ ⁇ ) is calculated from the analysis result (LVE analysis).
- the cellulose fine fibers of the present embodiment may have a modified fiber surface layer, if necessary.
- Modification methods include esterification, etherification, and urethanization.
- the modification method is preferably esterification, and esterification using saturated monocarboxylic acids is particularly preferred.
- Specific examples of the esterifying agent include relatively short-chain ones such as acetic acid, propionic acid, pentanoic acid (valeric acid), and hexanoic acid (caproic acid), and long-chain ones such as palmitic acid and stearic acid.
- the cellulose fine fibers of the present embodiment preferably have a zeta potential of ⁇ 50 mV or more and 50 mV or less.
- the zeta potential is within this range, the reactivity can be controlled to be low, so thermal decomposition is unlikely to occur, and when compounded in a resin or the like, coloring and a reduction in reinforcing effect are unlikely to occur.
- Cellulose fine fibers originally have a weak negative zeta potential of about -20 mV to 30 mV. preferably.
- Cellulose microfibers having a halogen content of 250 mass ppm or less>
- Cellulose microfibers may be cellulose microfibers (also referred to in this disclosure as low-halogen cellulose microfibers) having a halogen content of 250 ppm by weight or less.
- cellulose microfibers also referred to in this disclosure as low-halogen cellulose microfibers
- the presence of the cellulose fine fibers may cause problems such as decomposition of the resin and corrosion of the inside of devices such as kneading devices and molding devices.
- the halogen content of the low-halogen cellulose fine fibers is not more than a specific amount, even if the cellulose fine fibers are plant-derived, decomposition of the resin can be suppressed when the cellulose fine fibers and the resin are combined.
- the fiber-reinforced resin obtained using the low-halogen cellulose fine fibers has excellent stability during long-term storage, and can be stable even after undergoing multiple heat cycles associated with melt-kneading, such as material recycling.
- the low-halogen cellulose fine fibers can also suppress corrosion of equipment caused by the cellulose fine fibers.
- the low-halogen cellulose microfibers may include both unmodified cellulose microfibers and chemically modified cellulose microfibers.
- the halogen content in the low-halogen cellulose fine fibers means the halogen content remaining in the cellulose fine fibers after subjecting the cellulose fine fibers to the following [immersion/filtration treatment].
- the halogen content is a value measured according to [Halogen content measurement] below.
- Halogen content within the above range is also advantageous for suppressing corrosion inside devices such as kneading devices and molding devices.
- the halogens When halogens are mixed in cellulose fine fibers, the halogens may be firmly bound to cellulose by chemical or physical bonds.
- the cellulose fine fibers when the cellulose fine fibers are once immersed in pure water at 25 ° C. for 48 hours and then filtered and dried, as in the [immersion/filtration treatment] of the present disclosure, 80% by mass or more of can remain in the cellulose fine fibers. Due to their strong bond with cellulose, such halogens continue to remain even when cellulose fine fibers are combined with a resin, causing problems such as decomposition of the resin and corrosion of equipment.
- the cellulose fine fibers of the present embodiment are characterized by a low content of halogens that are firmly bound to cellulose. use the content of halogen still remaining in .
- Cellulose fine fibers are soaked in pure water at 25° C. and 48 hours. Specifically, the cellulose fine fibers are immersed in pure water at a solid content of 2% by mass in a glass beaker with a total volume of 200 mL, and are driven with a 3-1 motor (HEIDON BL-600 type, SUS propeller blades, 100 rpm). Allow to stand after stirring for 1 hour. Next, it is filtered under reduced pressure using a Teflon (registered trademark) membrane filter (opening 1 ⁇ m) to prepare a sheet with a basis weight of 10 g/m 2 , filtered and dried in a ventilation oven at 70° C. until the moisture content is 10% by mass or less.
- Teflon registered trademark
- Halogen is quantified by using an ion chromatography analyzer (INTEGRION CT model manufactured by THERMOFISHER) through a fluororesin tube. Quantification is performed based on a calibration curve prepared from samples with various halogen contents. At this time, the water content obtained in the above measurement is subtracted from the treated cellulose fine fibers. Finally, the value (mass ppm) obtained by converting the dry mass of the cellulose fine fibers after treatment (that is, in a state containing no water) is defined as the halogen content of the cellulose fine fibers of the present embodiment.
- an ion chromatography analyzer INTEGRION CT model manufactured by THERMOFISHER
- the halogen that the cellulose fine fibers of the present embodiment may contain may be in the form of a compound containing fluorine, chlorine, bromine, iodine, and/or astatine (that is, a halogen compound).
- the halogen compound may be a halide (ie, a compound of a halogen with a less electronegative element), a halogen salt, or the like, and may be an inorganic halogen compound or an organic halogen compound.
- a halogen compound ie, a compound of a halogen with a less electronegative element
- the low-halogen cellulose microfibers in one aspect, are chemically modified cellulose microfibers.
- the cellulose raw material for obtaining low-halogen cellulose fine fibers is plant-derived in one aspect, and in one aspect, softwood chips, hardwood chips, or non-wood-based cellulose raw materials (cotton-derived, hemp-derived, bagasse-derived, kenaf-derived, derived from bamboo, straw, etc.). It is preferable to use a cellulose raw material with a high degree of I-type crystallinity.
- the glucose content by analyzing the constituent sugars of the cellulose raw material for obtaining low-halogen cellulose fine fibers should be 90% by mass or more. is preferably 91% by mass or more, and even more preferably 93% by mass or more.
- impurities e.g., components other than polysaccharides, such as oil and fat components, various contaminant components, etc.
- it is preferably 99.5% by mass or less.
- the glucose content by analysis of constituent sugars is high not only in cellulose raw materials but also in 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 the upper limit is not particularly limited, it is 99.5% by mass or less in one aspect.
- the cellulose raw material for obtaining the low-halogen cellulose fine fibers is plant-derived among the above-mentioned purified cellulose fibers, that is, softwood chips, hardwood chips, or non-wood cellulose raw materials (derived from cotton, hemp, bagasse-derived, kenaf-derived, bamboo-derived, straw-derived, etc.) through the above steps.
- cellulose raw materials derived from cotton are preferred, and cotton linter pulp is particularly preferred, from the viewpoints of high cellulose purity, industrial availability, and quality stability.
- the cellulosic raw material for obtaining the low-halogen cellulose fine fibers may, in one aspect, be the aforementioned recycled material, preferably recycled cotton.
- the cellulose raw material or the above-mentioned purified cellulose raw material (for example, purified pulp) is further immersed in water and heat-treated at a temperature of 100 ° C. or higher, and the cellulose raw material or the above-mentioned purified cellulose raw material is treated with an aqueous sodium hydroxide solution. It is not possible to immerse in a strong alkaline aqueous solution (alkali concentration: 1% by mass to 10% by mass), allow it to stand or stir for a certain period of time in the range of 0 ° C. to 60 ° C., and then repeat washing with water. , is effective in reducing the halogen content in the cellulose raw material.
- a strong alkaline aqueous solution alkali concentration: 1% by mass to 10% by mass
- the cellulose raw material or the purified cellulose raw material described above may be further immersed in water and subjected to enzymatic treatment with a hemicellulose-degrading enzyme such as xylase or mannanase or cellulase at a temperature in the range of 35°C to 55°C. It can be effective for obtaining a purified cellulose raw material.
- performing purification by combining a plurality of the heat treatment, alkali treatment and enzyme treatment described above can be effective for obtaining a purified cellulose raw material with a higher purity.
- the halogen content (chlorine content in one aspect) in the cellulose raw material to be defibrated is preferably 300 ppm by mass or less, It is more preferably 250 mass ppm or less, still more preferably 200 mass ppm or less, particularly preferably 150 mass ppm or less, and significantly preferably 100 mass ppm or less.
- the halogen content (chlorine content in one aspect) of the cellulose raw material is preferably as low as possible, but from the viewpoint of production efficiency of cellulose fine fibers, in one aspect, it may be 10 mass ppm or more, or 25 mass ppm or more.
- the above halogen content is the amount per dry mass of the cellulose raw material measured by the same method as described above for the cellulose fine fibers.
- Cellulose microfibers especially low-halogen cellulose microfibers, preferably have a whiteness of 50% or more.
- the whiteness here uses a spectral whiteness meter/color difference meter (Nippon Denshoku Industries Co., Ltd. PF700 type), "ISO whiteness measurement method for diffuse blue light reflectance of paper, paperboard and pulp (JIS P8148 , ISO 2470)”.
- JIS P8148 , ISO 2470 JIS P8148 , ISO 2470
- the cellulose raw material or cellulose fine fibers are made into paper with a suction filtration device equipped with a polytetrafluoroethylene (PTFE) membrane filter so that the basis weight is 50 g/m 2 or more, and the paper is equilibrated at 80 ° C. It is dried until it becomes moist to prepare a cellulose sheet, which is used to measure the degree of whiteness with the apparatus described above.
- the whiteness of the cellulose fine fibers is more preferably 60% or more, still more preferably 70% or more, particularly preferably 80% or more, much preferably 90% or more, and most preferably 95%. That's it. Since the effect of the present embodiment increases as this value increases, the upper limit is not limited, but the practically obtainable range is preferably 99% or less.
- the cellulose raw material is preferably subjected to a bleaching treatment or the like prior to defibration treatment.
- the whiteness does not significantly decrease, so the whiteness of the cellulose raw material to be defibrated matches the whiteness of the cellulose fine fibers. That is, the whiteness of the cellulose raw material is preferably 50% or more, more preferably 60% or more, still more preferably 70% or more, particularly preferably 80% or more, and much preferably 90% or more. Yes, most preferably 95% or more. Since the effect of the present embodiment increases as this value increases, the upper limit is not limited, but the practically obtainable range is preferably 99% or less.
- the method for bleaching the cellulose raw material is one selected from the group consisting of chlorine treatment, alkali extraction treatment, hypochlorite treatment, chlorine dioxide treatment, oxygen bleaching treatment, hydrogen peroxide bleaching treatment, and ozone bleaching treatment. The above can be used.
- Chlorine treatment (hereinafter also referred to as “C” treatment) is a bleaching method using chlorine gas, and lignin is removed by chlorinating lignin in plant-derived cellulose raw materials (typically unbleached pulp). This is a solubilization process.
- Alkali extraction treatment (hereinafter also referred to as "E” treatment) is a treatment that dissolves and extracts alkali-soluble chlorinated lignin with alkali (caustic soda, etc.).
- Hypochlorite treatment (hereinafter also referred to as "H” treatment) is a treatment that bleaches carbohydrates such as cellulose and hemicellulose with sodium hypochlorite.
- Chlorine dioxide treatment (hereinafter also referred to as "D” treatment) is a treatment that uses chlorine dioxide to selectively decompose and remove lignin without destroying carbohydrates.
- Oxygen bleaching treatment (hereinafter also referred to as "O" treatment) is a treatment that uses oxygen to oxidatively decompose and extract lignin.
- Hydrogen peroxide bleaching treatment (hereinafter also referred to as "P" treatment) is a treatment that uses hydrogen peroxide to oxidatively decompose and extract lignin.
- Ozone bleaching treatment (hereinafter also referred to as "Z" treatment) is a treatment that uses ozone to oxidatively decompose and extract lignin.
- Effective combinations of bleaching methods include CEH treatment, CEHH treatment, CEHD treatment, CEHED treatment, CEHDED treatment, and CEDED treatment. These alphabetical arrangements indicate the sequence of each process, but the order may be changed depending on the purpose. Furthermore, C / D treatment in which part of the chlorine used in the chlorine treatment is replaced with chlorine dioxide (here, "/" means that both treatments sandwiching this are performed at the same time), and during the above sequence treatment A treatment in which C is replaced with C / D, a small amount of oxygen or hydrogen peroxide is added to strengthen the alkali during E treatment, E / O treatment or E / P treatment, and E during the above sequence treatment E/O treatment or E/P treatment, treatment in which oxygen is further added to E/O treatment or E/P treatment, and treatment in which E in the above sequence treatment is replaced by E/OH treatment, etc. and can be appropriately combined according to the application and purpose.
- ECF Elemental Chlorine Free, ie DE/ODD, E/OEDDP
- TCF Total Chlorine Free, ie E/OP-ZP
- the defibration of the cellulose raw material to obtain the low-halogen cellulose fine fibers may be performed on the cellulose raw material that has undergone or has not undergone the pretreatment of the present embodiment, but is preferably carried out on the cellulose raw material that has undergone the pretreatment. .
- a cellulose raw material adjusted to a specific fiber length by a pretreatment step such that the average fiber length is 3 mm or less and/or the number ratio of fibers with a fiber length of 3 mm or more is 20% or less is treated with an aqueous medium. , and the following treatment is applied to the obtained dispersion for beating treatment.
- aqueous media examples include water itself, monohydric alcohols such as ethanol, n-propanol, isopropanol and butanol, polyhydric alcohols such as ethylene glycol, diethylene glycol and glycerin, ketones such as acetone, and nitriles such as acetonitrile.
- a mixed medium of water and an organic solvent which is one or more of solvents, pyrrolidone-based solvents, and the like, can be mentioned.
- 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 ratio of the organic solvent is preferably set in view of the balance between fibrillation property and aggregation suppression. Beating is distinguished from pulverization as a pretreatment in this embodiment in that it is a wet process, and is distinguished from grinding as a pretreatment in this embodiment in that the fiber length of the cellulose to be subjected to treatment is different. be done.
- a cellulose raw material for example, a pulp sheet, etc.
- a pulper or a homomixer if necessary, followed by a beater, disc refiner, high-pressure homogenizer, water jet, disc mill, It is made finer using a beating device such as a ball mill, bead mill, masscolloider, homomixer, or the like.
- the beating treatment may be performed in one stage or in multiple stages, and in the case of performing in multiple stages, the same apparatus may be used multiple times, or different apparatuses may be used in combination.
- the cellulose raw material in the aqueous medium using the above pulper or homomixer before the beating treatment.
- the hydrophilicity of the cellulose raw material is reduced, so that the peripheral speed is 10 m/s or more, preferably 20 m/s or more in one aspect, It is more preferably 25 m/s or more, and in one aspect, preferably 90 m/s or less, preferably 80 m/s or less, and more preferably 50 m/s or less.
- the water in the aqueous medium used at this time highly pure water such as distilled water and ion-exchanged water can be effective.
- the cellulose fine fibers in the present embodiment have an appropriate fineness that is neither too coarse nor too fine, and have good homogeneity, so that they can be suitably used as a reinforcing filler for fiber-reinforced resins. Furthermore, it can be used as a prepreg material by being molded into a sheet and impregnated with a resin, and can be used as a building material such as concrete.
- One aspect of the present invention provides a fiber reinforced resin comprising the cellulosic microfibers of the present disclosure and a resin.
- the resin is impregnated into cellulose microfibers.
- the method for obtaining the fiber-reinforced resin is not particularly limited, but a method of mixing a resin dissolved in a solvent and cellulose fine fibers and drying the solvent, or a method of mixing cellulose fine fibers with a dispersant or the like and then drying, followed by A method of adding resin to melt-kneaded resin by a shaft extruder, a method of wet-process papermaking of cellulose fine fibers, forming a sheet and then impregnating resin to form a composite, mixing cellulose fine fibers and synthetic fibers, for example, wet-process A method of forming a non-woven fabric by papermaking and then heat-pressing at a temperature higher than the melting point of the synthetic fiber can be used.
- the method for producing a fiber-reinforced resin includes mixing cellulose fine fibers with synthetic fibers (synthetic staple fibers in one aspect), forming a nonwoven fabric by wet papermaking to form a nonwoven fabric, and then molding the nonwoven fabric by hot pressing.
- method hereinafter referred to as non-woven fabric method
- a slurry of cellulose fine fibers is prepared, this is subjected to a known dryer such as a spray dryer or a vacuum dryer to make a dry powder, and then a twin-screw extruder kneader is used.
- a method of adding the dry powder when melt-kneading the resin may be used.
- the resin (that is, matrix resin) used in this embodiment may be a thermosetting resin, a photocurable resin, or a thermoplastic resin.
- thermoplastic resins are preferable because the cellulose fine fibers of the present embodiment are excellent in heat resistance.
- the cellulose fine fibers of the present embodiment can be suitably combined with, for example, a resin having a melting point of 200° C. or higher and a melt-kneading temperature of 250° C. or higher.
- thermoplastic resins examples include styrene resins, acrylic resins, aliphatic or aromatic polycarbonate resins, aliphatic or aromatic polyester resins (polyethylene terephthalate, polylactic acid, etc.), chain polyolefin resins, cyclic Olefin resins, aliphatic or aromatic polyamide resins, polyphenylene ether resins, polyvinyl alcohol resins, polyoxyalkylene resins, polyphenylene sulfide resins, thermoplastic polyimide resins, polyacetal resins, polysulfone resins, non Crystalline fluorine-based resins, epoxy-based resins, and the like can be mentioned. These thermoplastic resins may be used alone or in combination of two or more.
- thermoplastic resins include polyolefins (polyethylene, polypropylene, etc.), polyesters (polyethylene terephthalate, polylactic acid, etc.), polyamides (PA6, PA66, PA4, PA12, aromatic polyamides, etc.), polyacrylonitrile, and polymethyl methacrylate. , polystyrene, polyvinyl alcohol, polyphenylene ether, polyoxymethylene, and polyphenylene sulfide.
- the melting point of the thermoplastic resin is 80° C. or higher, or 90° C. or higher, or 100° C. or higher, or 120° C. or higher, or 140° C. or higher, or 160° C. or higher, or 180° C. or higher, or 200° C. or higher. There may be, and in one aspect, it may be 300° C. or lower, or 250° C. or lower, or 230° C. or lower.
- the melting point is an endothermic peak that appears when the temperature is raised at a temperature elevation rate of 10 ° C./min using a differential scanning calorimeter (DSC) (if there are two or more, the highest temperature side peak) refers to the peak top temperature.
- DSC differential scanning calorimeter
- the synthetic fibers need to have a melting point because they are melted during hot pressing.
- resins having a melting point include polyethylene, polystyrene, polypropylene, ABS resin, polycarbonate, polyamide 6, polyamide 12, polyamide 66, polyvinyl chloride, methacrylic resin, polyvinyl alcohol, polyvinylidene chloride, polyvinylidene fluoride, polyvinylidene
- resins such as etherimide, polyoxymethylene, polysulfone, polyethylene terephthalate, and polyphenylene sulfide can be used, but other resins having a melting point may also be used.
- the melting point of these resins is preferably 250° C. or lower.
- the cellulose fine fibers which are mainly composed of type I crystals, begin to undergo significant weight loss due to thermal decomposition or oxidation between 260°C and 300°C, causing the composite to become colored and losing the inherent strength of cellulose.
- the melting point of the resin is preferably low, preferably 250 ° C. or less, and 230 ° C. The following are more preferred. Considering heat resistance during use, the melting point of the resin may be 80° C. or higher in one embodiment.
- the content of cellulose fine fibers contained in the fiber-reinforced resin is preferably 1% by mass or more, more preferably 5% by mass or more, and still more preferably 10% by mass or more in terms of good effect as reinforcing fibers. , more preferably 20% by mass or more. If the content of the cellulose fine fibers is too high, the continuous layer of the resin in the fiber reinforced resin tends to be broken and the performance of the fiber reinforced resin tends to decrease.
- the upper limit is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less, because it tends to cause poor molding due to low plasticity.
- the content of the resin in the fiber-reinforced resin is preferably 50% by mass or more, or 60% by mass or more, because the strength of the fiber-reinforced resin is likely to be increased by forming a continuous layer of the matrix resin. From the viewpoint of obtaining a satisfactory reinforcing effect of the cellulose fine fibers without reducing the content of the fine fibers too much, the content is preferably 99% by mass or less, 95% by mass or less, or 90% by mass or less.
- a non-woven fabric method As a method for obtaining a fiber-reinforced resin containing cellulose fine fibers and a resin, for example, a non-woven fabric method may be used.
- the nonwoven fabric comprises, in one aspect, the cellulosic microfibers of the present disclosure, and in one aspect, the cellulosic microfibers of the present disclosure and synthetic fibers.
- the strength of fiber-reinforced resins is greatly dependent on the orientation and continuity of the fibers in the resin, and controlling the orientation and continuity of the fibers is It is advantageous in controlling the strength of the reinforced resin.
- the cellulose fine fibers form a continuous layer in the resin by hydrogen bonding, and the continuous layer becomes a highly oriented structure in the two-dimensional plane direction, resulting in a material with excellent strength.
- a preferred example of the content of cellulose fine fibers in the nonwoven fabric may be in the same range from the same viewpoint as the content of cellulose fine fibers in the fiber-reinforced resin.
- the content of synthetic fibers in the nonwoven fabric tends to increase the strength of the fiber reinforced resin because the synthetic fibers can be melted to form a continuous layer during the production of the fiber reinforced resin, and the load of dehydration in the papermaking process during the production of the nonwoven fabric is reduced. It is preferably 50% by mass or more, or 60% by mass or more in terms of smallness, and from the viewpoint of obtaining a good reinforcing effect by the cellulose fine fibers so that the content of the cellulose fine fibers does not become too small, it is preferable. , 99% by mass or less, or 95% by mass or less, or 90% by mass or less.
- the synthetic fiber content may be set arbitrarily, but is more preferably 60% by mass or more and 90% by mass or less.
- the method for forming a nonwoven fabric includes a slurry preparation step in which cellulose fine fibers and synthetic fibers are stirred and mixed in a medium containing water to obtain a slurry, and a wet molded body (wet nonwoven fabric) is produced from the slurry by a wet papermaking method. , a drying step of drying the wet compact to obtain a non-woven fabric, and a hot-pressing step of hot-pressing the non-woven fabric at a temperature equal to or higher than the melting point of the synthetic fibers in the non-woven fabric to obtain a fiber-reinforced resin.
- Synthetic fiber The synthetic fibers used in the non-woven fabric manufacturing method are synthetic short fibers in one aspect.
- Synthetic short fibers refer to synthetic polymer fibers cut into arbitrary fiber lengths, and are sometimes called cut fibers or simply short fibers.
- Synthetic staple fibers may, in one aspect, be fibers with an average fiber length of 20 mm or less, or in one aspect, 10 mm or less.
- Synthetic staple fibers are fibrillated fibers obtained by fibrillating fibers cut after spinning by beating or the like, or fibrils obtained by spinning multi-branched fibers obtained by spinning by flash spinning or electrospinning, and then cutting them. It may be a synthetic fiber.
- Preferred examples of the synthetic fiber material are as exemplified above for the resin.
- the average fiber diameter of the synthetic fibers is preferably 0.1 ⁇ m or more, or 0.3 ⁇ m or more, or 1.0 ⁇ m or more from the viewpoint of availability of the synthetic fibers, and uniform blending with cellulose fine fibers and
- the thickness is preferably 50 ⁇ m or less, 40 ⁇ m or less, or 25 ⁇ m or less in terms of facilitating the formation of a homogeneous nonwoven fabric.
- the synthetic fiber has a relatively small average fiber diameter (for example, 10 ⁇ m or less), the difference in fiber diameter between the cellulose fine fiber and the synthetic fiber is small, so the air resistance coefficient of variation is low and the structure in the nonwoven fabric is uniform. becomes better.
- the synthetic fibers have a relatively large average fiber diameter (for example, more than 40 ⁇ m)
- the difference in fiber diameter between the cellulose fine fibers and the synthetic fibers is large, and there tends to be a large variation in the structure within the nonwoven fabric.
- the nonwoven fabric has a high basis weight (for example, 200 g/m 2 or more), it can exhibit a good (that is, low) air resistance coefficient of variation.
- the average fiber length of the synthetic fiber is preferably 0.5 mm or more, or 1.0 mm or more, or 1.5 mm or more from the viewpoint of obtaining a nonwoven fabric and a fiber reinforced resin having good mechanical properties. From the viewpoint of facilitating uniform dispersion among the fibers, it is preferably 20 mm or less, 15 mm or less, or 10 mm or less.
- the average fiber diameter and average fiber length of synthetic fibers are measured by the following methods. Each synthetic fiber sample is dispersed in water so that it becomes 0.01 to 0.1% by mass, and if necessary, after ultrasonic treatment (for several minutes), it is dropped onto a slide glass so that no air enters. and seal the periphery of the cover glass with nail polish (the concentration of the aqueous dispersion is adjusted so that the fibers do not become entangled with each other during microscopic imaging). After that, an image is acquired with a microscope (VHX-7000 manufactured by Keyence Corporation, the magnification is adjusted so that the long side of the fiber fits in the image), and the major and minor diameters of 100 fibers for each sample are measured. The average fiber length and average fiber diameter are obtained.
- the melting point of the synthetic fibers is preferably 300°C or less, more preferably 250°C or less, from the viewpoint of preventing thermal deterioration of the cellulose fine fibers during hot pressing.
- the melting point is preferably 90° C. or higher, more preferably 160° C. or higher.
- polymers constituting the synthetic fiber include those mentioned above as the resin.
- preferred polymers are polyamide, polyester (polyethylene terephthalate, polylactic acid, etc.), polyoxymethylene, polyacrylonitrile, etc., because they have high affinity with cellulose fine fibers and are easy to uniformly mix.
- Polyphenylene sulfide, polyphenylene ether, polyester, aromatic polyamide, etc. are suitable for applications requiring heat resistance. Specific procedures for the non-woven fabric forming method are exemplified below.
- the non-woven fabric method includes a slurry preparation step of stirring and mixing cellulose fine fibers and synthetic fibers in a medium containing water to obtain a slurry, a papermaking step of obtaining a wet molded body from the slurry by a wet papermaking method, and the wet molding. It includes a drying step of drying the body to obtain a non-woven fabric, and a hot-pressing step of hot-pressing the non-woven fabric at a temperature equal to or higher than the melting point of the synthetic fibers in the non-woven fabric to obtain a fiber-reinforced resin.
- cellulose fine fibers and synthetic fibers are stirred in a medium containing water, and the bundled synthetic fibers are monodispersed and highly distributed in the cellulose fine fibers.
- a stirring device a known stirring device such as a homomixer or a blender mixer can be used.
- the total solid concentration of the cellulose fine fibers and the synthetic fibers is determined from the viewpoint of increasing the elastic modulus of the fiber-reinforced resin finally obtained by highly dispersing the cellulose fine fibers and the synthetic fibers. From the viewpoint of increasing the strength and breaking strain by increasing the orientation of the fine fibers in the two-dimensional direction, it is preferably 3.0% by mass or less, or 1.0% by mass or less, or 0.8% by mass or less.
- a dispersing agent such as a surfactant or a thickening agent may be used for the purpose of improving the dispersibility of the synthetic fibers or improving the mixing properties of the synthetic fibers and the cellulose fine fibers.
- the slurry is dehydrated by a wet papermaking method to obtain a wet nonwoven fabric as a wet compact.
- dewatering is accomplished by suction filtering the slurry over the porous substrate.
- any filter medium with a pore size that dewaters the slurry and retains the cellulosic fines and synthetic fibers can be used.
- Specific filter media include filter paper, filter cloth, and metal mesh.
- the papermaking apparatus when an inclined wire paper machine, a fourdrinier paper machine, or a cylinder paper machine is used, it is possible to suitably obtain a flat sheet-shaped moist compact with few defects. Also, by using a metal mold for pulp molding or the like, a wet compact having a desired shape can be obtained.
- Papermaking may be a continuous type or a batch type, depending on the purpose. It is preferable from the viewpoint of cost to produce a sheet and form a roll-like product.
- continuous papermaking using a paper machine in the case of ordinary papermaking (for example, papermaking using beaten pulp fibers and synthetic fibers), an aqueous dispersion of fibers put on papermaking wires and Due to the generation of shear stress due to the running of the wire belt, the fibers in the aqueous dispersion are oriented in the running direction of the wire belt. Anisotropy in physical properties (strength, elastic modulus, etc.) occurs due to the orientation of fibers between the transverse direction (TD) and the direction (TD).
- the difference in physical properties from the TD direction is difficult to appear.
- This characteristic is that when a flat sheet as a non-woven fabric is produced by a paper machine, the cellulose fine fibers are isotropically based on inter-fiber association in an aqueous dispersion containing cellulose fine fibers and synthetic fibers that is fed into the paper machine.
- the synthetic fibers By forming a soft aggregate and forming a composite soft aggregate in which synthetic fibers are incorporated (that is, integrated) in the soft aggregate, the synthetic fibers have an anisotropic shape. Even if there is, it is considered to be due to being incorporated in the composite soft aggregate in a non-oriented state (that is, in a disordered and non-anisotropic state).
- the composite soft flocculate possesses strength to the extent that it does not collapse due to the shear stress based on the belt running applied to the water dispersion like the normal papermaking mentioned above. Therefore, the composite soft aggregate can be deposited and dehydrated on a belt while the synthetic fibers are fixed in a non-oriented state, and can form a non-anisotropic sheet by subsequent drying or the like.
- the ratio of physical properties in the MD/TD direction such as tensile strength, tensile modulus, bending strength, bending elastic modulus, linear thermal expansion coefficient, etc.
- the MD/TD physical property ratio is, in one aspect, 1 .6 or less, preferably 1.4 or less, more preferably 1.2 or less (see Example I-27 of this disclosure).
- the method of the present embodiment has an advantageous feature that anisotropy hardly appears not only in a portion with high flatness but also in a portion with high curvature even during three-dimensional molding such as the pulp molding method. show.
- the wet compact is at least dried to obtain a nonwoven fabric.
- the drying method is not particularly limited, but a drum dryer, pin tenter, or the like is used with a constant length drying type dryer that can dry the liquid medium while keeping the width of the wet compact at a constant length. is preferred.
- a constant length drying type dryer that can dry the liquid medium while keeping the width of the wet compact at a constant length. is preferred.
- the air resistance of the non-woven fabric depends on the composition ratio of the cellulose fine fibers and synthetic fibers that make up the slurry, the overall basis weight, the dispersion method of the stock solution, the blending conditions of various additives, the average fiber diameter of the cellulose fine fibers, etc. can be controlled.
- the drying temperature is preferably 45° C. or higher, or 60° C. or higher, or 80° C. or higher, or 85° C. or higher, from the viewpoint of drying efficiency (especially the viewpoint of obtaining good productivity by increasing the evaporation rate of the liquid medium). , or 90 ° C. or higher, preventing thermal denaturation of hydrophilic polymers (specifically, cellulose fine fibers and other components) that make up the nonwoven fabric, preventing a decrease in energy efficiency that affects cost, and reactive cross-linking From the viewpoint of preventing the reaction of the reactive cross-linking agent when using a cross-linking agent, the temperature is preferably 180° C. or lower, or 150° C. or lower, or 120° C. or lower, or 115° C.
- low-temperature drying at a temperature of 100° C. or less first, followed by multistage drying at a temperature exceeding 100° C. is also effective in obtaining a highly uniform nonwoven fabric.
- blocked polyisocyanate as a reactive cross-linking agent, the above conditions are suitable.
- the nonwoven fabric obtained in the drying process is pressed using a heated mold to melt and flow the synthetic fibers contained in the nonwoven fabric, fill the voids, and form a composite of cellulose fine fibers and resin.
- a fiber reinforced resin is obtained.
- the heating temperature may be above the melting point of the synthetic fiber, but near the melting point, the viscosity of the resin is high and voids may remain inside the composite. Therefore, the heating temperature is preferably 10° C. or more higher than the melting point of the synthetic fiber.
- a plurality of nonwoven fabrics may be laminated and subjected to the hot press process.
- a slurry of cellulose fine fibers is prepared in the same manner as described above in the nonwoven fabric production method, and this is subjected to a known dryer such as a spray dryer or a vacuum dryer to obtain a dry powder, and then biaxially.
- the fiber-reinforced resin may be produced by adding the dry powder when the resin is melt-kneaded by an extrusion kneader.
- the fiber-reinforced resin which is a composite of cellulose fine fibers and resin obtained by this embodiment, has excellent mechanical properties such as elastic modulus, strength, and breaking strain, and is used in automobile parts, building materials, home appliances, and the like. It can be suitably used for a wide range of uses.
- This disclosure also includes the following groups of items.
- ⁇ Item group I ⁇ [1] Cellulose fine fibers chemically modified at least on the surface, In the measurement with a fiber shape analyzer, the weighted average fiber length of fibers having a fiber length of 100 ⁇ m or more is 110 ⁇ m or more and 500 ⁇ m or less, Among fibers with a fiber length of 100 ⁇ m or more, the number frequency of fibers with a length-weighted fiber length of 411 ⁇ m or more is 54% or less. Cellulose microfibers.
- the average fiber diameter is 42.5 ⁇ m or less
- fine fiber area ratio is 90% or less
- the number frequency of fibers having a fiber length of 20 ⁇ m or more and 56 ⁇ m or less is 30% or more and 97% or less
- a fibrillation rate is 5% or less
- the cellulose fine fiber according to item 1 above which satisfies all of [3]
- the cellulose fine fiber according to any one of items 1 to 6 above which has a degree of crystallinity of 60% or more.
- a nonwoven fabric comprising the cellulose fine fibers according to any one of items 1 to 7 above.
- the nonwoven fabric according to Item 9 above containing 50% by mass or more of synthetic fibers having a melting point of 300°C or less.
- a fiber-reinforced resin comprising the nonwoven fabric according to item 9 and a resin impregnated in the nonwoven fabric.
- a method for producing a fiber-reinforced resin containing cellulose fine fibers and a resin comprising: A step of hot-pressing the nonwoven fabric according to item 10 to obtain a fiber reinforced resin, A method for producing a fiber-reinforced resin, wherein the heat pressing is performed at a temperature equal to or higher than the melting point of the synthetic fiber.
- ⁇ Item group II ⁇ [1] In the measurement of the fiber shape automatic analyzer, (i) an average fiber length of 130 ⁇ m or more and 350 ⁇ m or less; (ii) an average fiber diameter of 35 ⁇ m or less, (iii) a fine fiber area ratio of 75% or less, (iv) Among fibers with a fiber length of less than 100 ⁇ m, the number frequency of fibers having a fiber length of 20 ⁇ m or more and 56 ⁇ m or less is 75% or less, (v) the number frequency of fibers having a fiber length of 411 ⁇ m or more among the fibers having a fiber length of 100 ⁇ m or more is 30% or less, and (vi) the fibrillation rate is 5.0% or less, Cellulose fine fiber that fulfills all of the requirements.
- the cellulose fine fibers according to item 1 wherein the reciprocal of the yield strain ( ⁇ ) in strain dispersion measurement, 1/ ⁇ , is 200 or more in the water-dispersed slurry having a concentration of 0.75% by mass.
- the cellulose fine fiber according to item 1 or 2 above which has a zeta potential of ⁇ 50 mV or more and 50 mV or less.
- a fiber-reinforced resin containing 1.0% by mass or more of the cellulose fine fibers according to any one of Items 1 to 3 above and a resin.
- a nonwoven fabric containing 1.0% by mass or more of the cellulose fine fibers according to any one of Items 1 to 3 above.
- the nonwoven fabric according to Item 5 above containing 50% by mass or more of synthetic fibers having a melting point of 250°C or less.
- a method for producing a fiber-reinforced resin containing cellulose fine fibers and a synthetic resin comprising: A step of hot-pressing a nonwoven fabric containing cellulose fine fibers and synthetic fibers to obtain a fiber reinforced resin,
- the nonwoven fabric is the nonwoven fabric according to item 5 or 6 above, A method for producing a fiber-reinforced resin, wherein the heat pressing is performed at a temperature equal to or higher than the melting point of the synthetic fiber.
- ⁇ Item group III ⁇ [1] Cellulose fine fibers that are plant-derived and have a halogen content (more specifically, the content of halogen bound to cellulose) of 250 ppm by mass or less. [2] The cellulose fine fibers according to Item 1 above, which have a whiteness of 50% or more. [3] A method for producing cellulose fine fibers according to item 1 or 2 above, A method for producing cellulose fine fibers, comprising a step of defibrating a cellulose raw material having a halogen content (more specifically, a content of halogen bound to cellulose) of 300 ppm by mass or less.
- Example I ⁇ Measurement method ⁇ [Fiber shape automatic analyzer measurement] Various properties of cellulose fine fibers were evaluated by the following procedure using an automatic fiber shape analyzer (MorfiNeo manufactured by TechPap). 1. Cellulose fine fibers were dispersed in pure water to prepare 1 L of aqueous dispersion. Here, the solid content final concentration of the cellulose fine fibers was set to 0.003 to 0.005% by mass. Regarding the aqueous dispersions containing less than 2% by mass of cellulose fine fibers before dilution (i.e., Production Examples 6, 7, and 11), they were simply mixed with a spatula or the like.
- a high shear homogenizer manufactured by IKA, trade name "Ultra Turrax T18" was used. Processing conditions: rotation Dispersion treatment was performed at several 25,000 rpm for 5 minutes. In any of the production examples, since they are dispersed in a medium other than water, they were dispersed in a sufficient amount of pure water using the high-shear homogenizer under the treatment conditions: 25,000 rpm for 5 minutes. After that, the medium is removed by means such as suction filtration, and the high-shear homogenizer is used again to immerse the mixture in pure water.
- the medium was replaced with water by carrying out a dispersion treatment so as to achieve mass %.
- the aqueous dispersion prepared in 1 was subjected to an autosampler and measured. 3.
- the measurement results were output in txt format (or csv format). 4.
- Each shape parameter was extracted or calculated from the measurement results. For each parameter, the following values among the measurement results were used.
- Length-weighted average fiber length in normal fibers (fibers with a fiber length of 100 ⁇ m or more): Mean length-weighted Length [ ⁇ m] Average fiber length in normal fibers (fibers with a fiber length of 100 ⁇ m or more): Mean arithmetic length [ ⁇ m] Number frequency of fibers having a fiber length of 411 ⁇ m or more in ordinary fibers: Calculated from the length-weighted fiber length distribution (length-weighted fiber length, ⁇ m) of ordinary fibers.
- Average fiber diameter Mean fiber width [ ⁇ m]
- Fine fiber area ratio Fine content, % in Area Number frequency of fibers having a fiber length of 20 ⁇ m or more and 56 ⁇ m or less in fine fibers (fibers having a fiber length of less than 100 ⁇ m): Calculated from the fiber length distribution (Fine length, ⁇ m: FL) of fine fibers.
- Fibrillation rate MacroFibrillation index [%]
- a cellulose fine fiber aqueous dispersion with a solid content concentration of 0.2 to 2% by mass is diluted with dimethyl sulfoxide (DMSO) to a solid content of 5 ppm by mass, and a homogenizer (manufactured by IKA, trade name “Ultra Turrax T18”) is used. The mixture was stirred at 3000 rpm for 30 seconds to obtain a DMSO dispersion.
- DMSO dimethyl sulfoxide
- IKA trade name “Ultra Turrax T18”
- the substrate on which the obtained cellulose fine fibers were fixed was observed with a scanning electron microscope (SEM) at an acceleration voltage of 1.5 kV, an observation magnification of 400 times, and a resolution of 400 pixels or more per 100 ⁇ m. I took the image. 5.
- the number of pixels corresponding to the threshold value of 15 ⁇ m 2 was calculated from the number of pixels on the scale bar of the SEM image.
- a binarized image was created from the acquired SEM image by the MaxEntropy method using image processing software ImageJ. 7.
- the binarized image was subjected to particle analysis using ImageJ's Analyze Particle, and the area (pixel) of a single fiber of cellulose fine fibers was calculated. 8.
- the particle analysis results of the four captured images are totaled, two pixels or less are deleted as noise, and the area of less than 15 ⁇ m 2 is defined as ultrafine fibers as a threshold, and the area of ultrafine fibers of less than 15 ⁇ m 2 in the total area of cellulose fine fibers. The ratio of was calculated.
- glucose content by analyzing the constituent sugars of the cellulose fine fibers was determined according to the analysis procedure of the National Renewable Energy Laboratory of the U.S. Department of Energy (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).
- the degree of acetyl substitution (DS) of cellulose fine fibers was measured using an infrared spectrometer (FT/IR-6200, manufactured by JASCO Corporation) and a nuclear magnetic resonance spectrometer (NMR) (AVANCE III, manufactured by Bruker, 500 MHz) in the following procedure. evaluated.
- the degree of acetyl substitution (DS) was calculated based on the peak intensity ratio between the peak derived from the acetyl group and the peak derived from the cellulose skeleton from the reflective infrared absorption spectrum of the cellulose fine fiber.
- the peak of the C ⁇ O absorption band based on the acetyl group appears at 1730 cm ⁇ 1
- the peak of the C—O absorption band based on the cellulose backbone chain appears at 1030 cm ⁇ 1 .
- Crystallinity The crystallinity of cellulose fine fibers was evaluated by the following method using an X-ray diffractometer (MiniFlex II manufactured by Rigaku Corporation). The diffraction pattern (2 ⁇ /deg. is 10 to 30) when the sample was measured by wide-angle X-ray diffraction was obtained by the Segal method using the following formula.
- Halogen was quantified by using an ion chromatography analyzer (INTEGRION CT model manufactured by THERMOFISHER) through a fluororesin tube. The quantification was performed based on a calibration curve prepared with samples having various halogen contents. At this time, the loss on drying method (2.00 g of a cellulose sample was introduced into a glass weighing bottle, dried at 60 ° C. for 15 hours, then at 105 ° C. for 2 hours, weighed to a constant weight in a desiccator, and weighed as follows.
- INTEGRION CT model manufactured by THERMOFISHER ion chromatography analyzer
- Moisture content (mass%) (Sample weight before drying - Sample weight after drying) / (Sample weight before drying) x 100), the water content in the cellulose raw material after treatment or in the cellulose fine fiber after treatment minus the amount. Finally, the content of halogen remaining in the cellulose fibers (mass ppm) was converted to the dry mass of the cellulose raw material after treatment or the cellulose fine fibers after treatment (that is, in a state containing no water).
- Linter pulp A Linter pulp A (hereinafter referred to as pulp A), which is a natural cellulose obtained from Japan Pulp & Paper Co., Ltd., had a length-weighted average fiber length of 1660 ⁇ m measured with the aforementioned automatic fiber shape analyzer.
- Linter pulp B Linter pulp B (hereinafter referred to as pulp B), which is a natural cellulose obtained from Japan Pulp & Paper Co., Ltd., had a weighted average fiber length of 1006 ⁇ m as measured by the aforementioned automatic fiber shape analyzer.
- pulp C Wood pulp (NBLP) C (hereinafter referred to as pulp C), which is natural cellulose obtained from Japan Pulp & Paper Co., Ltd., had a length-weighted average fiber length of 1315 ⁇ m as measured by the aforementioned fiber shape automatic analyzer. .
- acetylated linter pulp D (Acetylated linter pulp D) The pulp A was immersed in dimethyl sulfoxide so that the pulp concentration was 5% by mass, 0.1% by mass of potassium carbonate was added as a catalyst, and the pulp was sufficiently dispersed and swollen with a stirring blade. The mixture was heated to 60° C. and vinyl acetate was added for acetylation to obtain acetylated linter pulp D (hereinafter referred to as acetylated pulp D).
- acetylated linter pulp E (Acetylated linter pulp E) The pulp B was immersed in dimethyl sulfoxide so that the pulp concentration was 5% by mass, 0.1% by mass of potassium carbonate was added as a catalyst, and the pulp was sufficiently dispersed and swollen with a stirring blade. The mixture was heated to 60° C. and vinyl acetate was added for acetylation to obtain acetylated linter pulp E (hereinafter referred to as acetylated pulp E).
- Pulp A was immersed in water so that the solid content was 1.5% by mass, and the slurry obtained by dispersing using a lab pulper (manufactured by Aikawa Tekko Co., Ltd.) was processed with a single disc refiner (SDR14 type lab refiner manufactured by Aikawa Tekko Co., Ltd.). The pulp was defibrated by introducing it into a defibrating device comprising a compression DISK type) and tanks A and B connected by wiring via the disc refiner.
- a lab pulper manufactured by Aikawa Tekko Co., Ltd.
- SDR14 type lab refiner manufactured by Aikawa Tekko Co., Ltd.
- the slurry is transferred from the tank A into which the slurry is charged to the tank B through the disc refiner and stored, and at the stage where the slurry in the tank A has been treated, the slurry is continuously transferred from the tank B through the disc refiner.
- Defiberization was performed by controlling the number of passes through the disc refiner (the number of passes) according to the method of feeding and storing the liquid to the tank A.
- a ball screw type jack and a speed reducer were provided as a mechanism for adjusting the blade distance of the disc refiner.
- the deviation width of the blade-to-blade distance during the beating process after reaching the target blade-to-blade distance was 0.005 mm or less as measured by a displacement sensor.
- a blade (disc blade A) with a blade width of 4.0 mm and a blade groove ratio of 0.89 was used, and after 30 passes with a blade distance of 0.25 mm, the blade width was 0.8 mm and the blade groove ratio was A 0.53 blade (disk blade B) was used and 30 passes were made with a blade distance of 0.25 mm.
- the resulting slurry was treated with a high-pressure homogenizer (NS3015H, manufactured by Niro Soavi) for 3 passes at 80 MPa.
- a high-pressure homogenizer (NS3015H, manufactured by Niro Soavi) for 3 passes at 80 MPa.
- N3015H manufactured by Niro Soavi
- two tanks were provided in the same manner as in the disc refiner treatment, and defibration was performed by controlling the number of passes of the high-pressure homogenizer treatment.
- a wet cake having a solid content of 18% by mass obtained by filtering the resulting unmodified cellulose fine fiber slurry under reduced pressure was placed in a reaction vessel, and dimethyl sulfoxide (DMSO) was added so that the solid content was 2% by mass. Potassium carbonate corresponding to % by mass was added and heated to 60° C. with uniform stirring. Vinyl acetate was added thereto, and acetylation was carried out until a predetermined degree of substitution was reached. After the reaction, 10% by mass of quenching water is added, and agitation and filtration are repeated using a pressure filter using pure water that is 50 times the mass of the cellulose solid content to thoroughly wash the solvent, etc., and wet the acetylated cellulose fine fibers. got cake.
- DMSO dimethyl sulfoxide
- a wet cake having a solid content of 18% by mass obtained by filtering the resulting unmodified cellulose fine fiber slurry under reduced pressure was placed in a reaction vessel, and dimethyl sulfoxide (DMSO) was added so that the solid content was 2% by mass. Potassium carbonate corresponding to % by mass was added and heated to 60° C. with uniform stirring. Vinyl acetate was added thereto, and acetylation was carried out until a predetermined degree of substitution was reached. After the reaction, 10% by mass of quenching water is added, and agitation and filtration are repeated using a pressure filter using pure water that is 50 times the mass of the cellulose solid content to thoroughly wash the solvent, etc., and wet the acetylated cellulose fine fibers. got cake.
- DMSO dimethyl sulfoxide
- the obtained slurry was treated with a high-pressure homogenizer for 5 passes.
- a wet cake having a solid content of 18% by mass obtained by filtering the resulting unmodified cellulose fine fiber slurry under reduced pressure was placed in a reaction vessel, and dimethyl sulfoxide (DMSO) was added so that the solid content was 2% by mass. Potassium carbonate corresponding to % by mass was added and heated to 60° C. with uniform stirring. Vinyl acetate was added thereto, and acetylation was carried out until a predetermined degree of substitution was reached. After the reaction, 10% by mass of quenching water is added, and agitation and filtration are repeated using a pressure filter using pure water that is 50 times the mass of the cellulose solid content to thoroughly wash the solvent, etc., and wet the acetylated cellulose fine fibers. got cake.
- DMSO dimethyl sulfoxide
- the obtained slurry was treated with a high-pressure homogenizer for 5 passes.
- a wet cake having a solid content of 18% by mass obtained by filtering the resulting unmodified cellulose fine fiber slurry under reduced pressure was placed in a reaction vessel, and dimethyl sulfoxide (DMSO) was added so that the solid content was 2% by mass. Potassium carbonate corresponding to % by mass was added and heated to 60° C. with uniform stirring. Vinyl acetate was added thereto, and acetylation was carried out until a predetermined degree of substitution was reached. After the reaction, 10% by mass of quenching water is added, and agitation and filtration are repeated using a pressure filter using pure water that is 50 times the mass of the cellulose solid content to thoroughly wash the solvent, etc., and wet the acetylated cellulose fine fibers. got cake.
- DMSO dimethyl sulfoxide
- the resulting slurry was treated with a high-pressure homogenizer for 10 passes.
- a wet cake having a solid content of 18% by mass obtained by filtering the resulting unmodified cellulose fine fiber slurry under reduced pressure was placed in a reaction vessel, and dimethyl sulfoxide (DMSO) was added so that the solid content was 2% by mass. Potassium carbonate corresponding to % by mass was added and heated to 60° C. with uniform stirring. Vinyl acetate was added thereto, and acetylation was carried out until a predetermined degree of substitution was reached. After the reaction, 10% by mass of quenching water is added, and agitation and filtration are repeated using a pressure filter using pure water that is 50 times the mass of the cellulose solid content to thoroughly wash the solvent, etc., and wet the acetylated cellulose fine fibers. got cake.
- DMSO dimethyl sulfoxide
- the resulting slurry was treated with a high-pressure homogenizer for 10 passes.
- the obtained slurry was treated with a high-pressure homogenizer for 3 passes.
- a wet cake having a solid content of 18% by mass obtained by filtering the resulting unmodified cellulose fine fiber slurry under reduced pressure was placed in a reaction vessel, and dimethyl sulfoxide (DMSO) was added so that the solid content was 2% by mass. Potassium carbonate corresponding to % by mass was added and heated to 60° C. with uniform stirring. Vinyl acetate was added thereto, and acetylation was carried out until a predetermined degree of substitution was reached. After the reaction, 10% by mass of quenching water is added, and agitation and filtration are repeated using a pressure filter using pure water that is 50 times the mass of the cellulose solid content to thoroughly wash the solvent, etc., and wet the acetylated cellulose fine fibers. got cake.
- DMSO dimethyl sulfoxide
- the obtained slurry was treated with a high-pressure homogenizer for 5 passes.
- a wet cake having a solid content of 18% by mass obtained by filtering the resulting unmodified cellulose fine fiber slurry under reduced pressure was placed in a reaction vessel, and dimethyl sulfoxide (DMSO) was added so that the solid content was 2% by mass. Potassium carbonate corresponding to % by mass was added and heated to 60° C. with uniform stirring. Vinyl acetate was added thereto, and acetylation was carried out until a predetermined degree of substitution was reached. After the reaction, 10% by mass of quenching water is added, and agitation and filtration are repeated using a pressure filter using pure water that is 50 times the mass of the cellulose solid content to thoroughly wash the solvent, etc., and wet the acetylated cellulose fine fibers. got cake.
- DMSO dimethyl sulfoxide
- the resulting slurry was treated with a high-pressure homogenizer for 10 passes.
- a wet cake having a solid content of 18% by mass obtained by filtering the resulting unmodified cellulose fine fiber slurry under reduced pressure was placed in a reaction vessel, and dimethyl sulfoxide (DMSO) was added so that the solid content was 2% by mass. Potassium carbonate corresponding to % by mass was added and heated to 60° C. with uniform stirring. Vinyl acetate was added thereto, and acetylation was carried out until a predetermined degree of substitution was reached. After the reaction, 10% by mass of quenching water is added, and agitation and filtration are repeated using a pressure filter using pure water that is 50 times the mass of the cellulose solid content to thoroughly wash the solvent, etc., and wet the acetylated cellulose fine fibers. got cake.
- DMSO dimethyl sulfoxide
- the resulting slurry was treated with a high-pressure homogenizer for 10 passes.
- DMSO was added to a wet cake with a solid content of 18% by mass obtained by filtering the obtained unmodified cellulose fine fiber slurry under reduced pressure, and after stirring, suction filtration was repeated twice to remove moisture.
- DMSO-substituted cellulose fine fibers were added to a DMSO solution in which maleic anhydride was dissolved, and the mixture was reacted with heating until a predetermined degree of substitution was reached. After the reaction, pure water washing, acetone washing, and pure water washing were repeated to remove the solvent, unreacted reagents and by-products, and a wet cake of maleic acid-modified cellulose fine fibers was obtained.
- the resulting slurry was treated with a high-pressure homogenizer for one pass.
- a wet cake having a solid content of 18% by mass obtained by filtering the resulting unmodified cellulose fine fiber slurry under reduced pressure was placed in a reaction vessel, and dimethyl sulfoxide (DMSO) was added so that the solid content was 2% by mass. Potassium carbonate corresponding to % by mass was added and heated to 60° C. with uniform stirring. Vinyl acetate was added thereto, and acetylation was carried out until a predetermined degree of substitution was reached. After the reaction, 10% by mass of quenching water is added, and agitation and filtration are repeated using a pressure filter using pure water that is 50 times the mass of the cellulose solid content to thoroughly wash the solvent, etc., and wet the acetylated cellulose fine fibers. got cake.
- DMSO dimethyl sulfoxide
- a wet cake having a solid content of 18% by mass obtained by filtering the resulting unmodified cellulose fine fiber slurry under reduced pressure was placed in a reaction vessel, and dimethyl sulfoxide (DMSO) was added so that the solid content was 2% by mass. Potassium carbonate corresponding to % by mass was added and heated to 60° C. with uniform stirring. Vinyl acetate was added thereto, and acetylation was carried out until a predetermined degree of substitution was reached. After the reaction, 10% by mass of quenching water is added, and agitation and filtration are repeated using a pressure filter using pure water that is 50 times the mass of the cellulose solid content to thoroughly wash the solvent, etc., and wet the acetylated cellulose fine fibers. got cake.
- DMSO dimethyl sulfoxide
- a wet cake having a solid content of 18% by mass obtained by filtering the resulting unmodified cellulose fine fiber slurry under reduced pressure was placed in a reaction vessel, and dimethyl sulfoxide (DMSO) was added so that the solid content was 2% by mass. Potassium carbonate corresponding to % by mass was added and heated to 60° C. with uniform stirring. Vinyl acetate was added thereto, and acetylation was carried out until a predetermined degree of substitution was reached. After the reaction, 10% by mass of quenching water is added, and agitation and filtration are repeated using a pressure filter using pure water that is 50 times the mass of the cellulose solid content to thoroughly wash the solvent, etc., and wet the acetylated cellulose fine fibers. got cake.
- DMSO dimethyl sulfoxide
- a wet cake having a solid content of 18% by mass obtained by filtering the resulting unmodified cellulose fine fiber slurry under reduced pressure was placed in a reaction vessel, and dimethyl sulfoxide (DMSO) was added so that the solid content was 2% by mass. Potassium carbonate corresponding to % by mass was added and heated to 60° C. with uniform stirring. Vinyl acetate was added thereto, and acetylation was carried out until a predetermined degree of substitution was reached. After the reaction, 10% by mass of quenching water is added, and agitation and filtration are repeated using a pressure filter using pure water that is 50 times the mass of the cellulose solid content to thoroughly wash the solvent, etc., and wet the acetylated cellulose fine fibers. got cake.
- DMSO dimethyl sulfoxide
- the obtained slurry was treated with a high-pressure homogenizer for 20 passes.
- a wet cake having a solid content of 18% by mass obtained by filtering the resulting unmodified cellulose fine fiber slurry under reduced pressure was placed in a reaction vessel, and dimethyl sulfoxide (DMSO) was added so that the solid content was 2% by mass. Potassium carbonate corresponding to % by mass was added and heated to 60° C. with uniform stirring. Vinyl acetate was added thereto, and acetylation was carried out until a predetermined degree of substitution was reached. After the reaction, 10% by mass of quenching water is added, and agitation and filtration are repeated using a pressure filter using pure water that is 50 times the mass of the cellulose solid content to thoroughly wash the solvent, etc., and wet the acetylated cellulose fine fibers. got cake.
- DMSO dimethyl sulfoxide
- the resulting slurry was treated with a high-pressure homogenizer for 15 passes.
- a wet cake having a solid content of 18% by mass obtained by filtering the resulting unmodified cellulose fine fiber slurry under reduced pressure was placed in a reaction vessel, and dimethyl sulfoxide (DMSO) was added so that the solid content was 2% by mass. Potassium carbonate corresponding to % by mass was added and heated to 60° C. with uniform stirring. Vinyl acetate was added thereto, and acetylation was carried out until a predetermined degree of substitution was reached. After the reaction, 10% by mass of quenching water is added, and agitation and filtration are repeated using a pressure filter using pure water that is 50 times the mass of the cellulose solid content to thoroughly wash the solvent, etc., and wet the acetylated cellulose fine fibers. got cake.
- DMSO dimethyl sulfoxide
- Pulp A was immersed in water so that the solid content was 1.5% by mass, and dispersed with a lab pulper. After 80 passes at 0.20 mm, a blade with a blade width of 0.8 mm and a blade groove ratio of 0.53 was used, and 100 passes were made at a blade distance of 0.10 mm.
- the obtained slurry was treated with a high-pressure homogenizer for 5 passes.
- a wet cake having a solid content of 18% by mass obtained by filtering the resulting unmodified cellulose fine fiber slurry under reduced pressure was placed in a reaction vessel, and dimethyl sulfoxide (DMSO) was added so that the solid content was 2% by mass. Potassium carbonate corresponding to % by mass was added and heated to 60° C. with uniform stirring. Vinyl acetate was added thereto, and acetylation was carried out until a predetermined degree of substitution was reached. After the reaction, 10% by mass of quenching water is added, and agitation and filtration are repeated using a pressure filter using pure water that is 50 times the mass of the cellulose solid content to thoroughly wash the solvent, etc., and wet the acetylated cellulose fine fibers. got cake.
- DMSO dimethyl sulfoxide
- Tables 1 and 2 show the evaluation results of the obtained chemically modified cellulose fine fibers.
- ⁇ Manufacturing of fiber reinforced resin ⁇ (Compositing by injection molding: Examples I-1 to I-12, Comparative Examples I-1 to I-7) Using each of the obtained chemically modified cellulose fine fibers, a composite fiber-reinforced resin was produced by injection molding in the following procedure. 1.
- the wet cakes of the chemically modified cellulose fine fibers produced in Production Examples 1 to 12 and Comparative Production Examples 1 to 7 were respectively added to hexafluoroisopropanol (hereinafter referred to as HFIP) with a homogenizer (IKA Co., Ltd.) so that the solid content concentration was 1% by volume.
- a dispersion treatment was performed for 3 minutes at a rotation speed of 12,000 rpm using Ultra Turrax T18). 2.
- a solution was prepared by dissolving polyamide 6 (1013B, manufactured by Ube Industries, Ltd.) in HFIP at a solid content of 1% by mass. 3. Place 1 and 2 in a container so that the solid content mass ratio of chemically modified cellulose fine fibers and polyamide 6 is 1: 9, and mix 2, 2, and 2 with a rotation/intersection mixer (Awatori Mixer ARE-310, manufactured by Thinky). Mixed for 5 minutes at 000 rpm. 4. The resulting mixture of 3 was cast on a release film (X88B, manufactured by Mitsui Chemicals Tohcello, Inc.) and dried in an oven at 80° C. for 1 hour. 5. 4 was pulverized with a desktop pulverizer (Mini Speed Mill MS-05 manufactured by Labnext). 6.
- the powder of 5 was dried in a vacuum dryer for more than 24 hours. 7. 6 was kneaded for 2 minutes with a small kneader (manufactured by DSM, Xplore MC 15HT) at a temperature of 250°C and a rotation speed of 200 rpm. 8. After kneading, the resin is poured into an injection molding machine (Xplore IM12), and a strip-shaped test piece of width: 10 mm, length: 80 mm, thickness: 4 mm for bending test and ISO-37 for tensile test. A test piece (as a fiber-reinforced resin) was produced. Table 3 shows the results of bending test and tensile test of the obtained test piece.
- the papermaking slurry prepared above is placed in a batch-type paper machine (automatic rectangular sheet machine, 25 cm x 25 cm, 80 mesh, manufactured by Kumagai Riki Kogyo Co., Ltd.) in which a filter cloth ( TT35 , manufactured by Shikishima Canvas Co., Ltd.) is set. After that, papermaking (dehydration) was performed at a pressure reduction degree of 50 kPa with respect to the atmospheric pressure.
- the wet paper web consisting of the wet concentrated composition on the resulting filter cloth was peeled off from the wire and pressed at a pressure of 1 kg/cm 2 for 1 minute. Then, it was dried for about 120 seconds with a drum dryer whose surface temperature was set at 130° C. to obtain a nonwoven fabric.
- Four nonwoven fabrics of 10 cm square were cut out from the obtained nonwoven fabric, laminated, and sandwiched between PET films having a thickness of 0.1 ⁇ m. This was heat-molded for 5 minutes with a hot press at a temperature of 200° C. and a molding pressure of 10 kg/cm 2 .
- the thickness of the molding was controlled by providing a 1.5 mm spacer made of stainless steel between the PET films.
- the above-prepared papermaking slurry is passed to a batch-type paper machine (automatic rectangular sheet machine, 25 cm x 25 cm, 80 mesh, manufactured by Kumagai Riki Kogyo Co., Ltd.) set with a filter cloth (TT35, manufactured by Shikishima Canvas Co., Ltd.) to a basis weight of 300 g/m 2 .
- a batch-type paper machine automated rectangular sheet machine, 25 cm x 25 cm, 80 mesh, manufactured by Kumagai Riki Kogyo Co., Ltd.
- TT35 manufactured by Shikishima Canvas Co., Ltd.
- the wet paper web consisting of the wet concentrated composition on the resulting filter cloth was peeled off from the wire and pressed at a pressure of 1 kg/cm 2 for 1 minute. Then, it was dried for about 120 seconds with a drum dryer whose surface temperature was set at 130° C. to obtain a nonwoven fabric.
- Four nonwoven fabrics of 10 cm square were cut out from the obtained nonwoven fabric, laminated, and sandwiched between Teflon (registered trademark) sheets having a thickness of 0.1 ⁇ m. This was heat molded for 5 minutes at a temperature of 300° C. and a molding pressure of 10 kg/cm 2 using a hot press.
- the thickness of the molding was controlled by providing a 1.5 mm spacer made of stainless steel between the PET films.
- Example II ⁇ Measurement method ⁇ [Fiber shape automatic analyzer measurement] Various properties of the cellulose fine fibers were measured using an automatic fiber shape analyzer (Morfi neo manufactured by Technidyne) according to the following procedures. 1. Cellulose fine fibers were dispersed in pure water to prepare 1 L of aqueous dispersion. The solid content final concentration was adjusted to about 0.004% by mass. Since all cellulose fine fibers were water dispersions with a solid content concentration of 2% by mass or less, dispersion treatment was performed by shaking in a sealed container with a filling rate of 75% by volume or less. 2. 1. The water dispersion prepared in 1 was subjected to an autosampler and measured. 3. The measurement results were output in txt format (or csv format). 4. Shape parameters similar to those in Example I were extracted or calculated from the measurement results.
- the solid content final concentration of the cellulose fine fibers was set to 0.75% by mass. Since all cellulose fine fibers were water dispersions with a solid content concentration of 2% by mass or less, dispersion treatment was performed by shaking in a sealed container with a filling rate of 75% by volume or less. 2. 1. The aqueous dispersion prepared in 1 was allowed to stand at 25° C. for 24 hours or more. 3. A jig was attached to the rheometer, and 17.0 ⁇ 1.0 g of a cellulose fine fiber aqueous dispersion was charged using a dropper. 4. Measurement was carried out, yield strain ( ⁇ ) was calculated by LVE analysis, and its reciprocal (1/ ⁇ ) was calculated.
- ⁇ Preparation of cellulose fine fibers ⁇ (Cellulose fine fiber A) Using linter pulp, which is a natural cellulose obtained from Japan Pulp & Paper Co., Ltd., the linter pulp is immersed in water so that the linter pulp is 1.5% by mass, and is easily dispersed using a lab pulper (manufactured by Aikawa Iron Works). After that, the liquid was sent to the tank. A single disk refiner (previous stage) equipped with a disk with a blade width of 2.5 mm, a groove width of 7.0 mm, and a blade groove ratio of 0.36 connected to the tank was used to refine the slurry while circulating it. .
- cellulose fine fiber A (MFC-A). Table 6 shows the results of analysis of various fiber shape parameters and rheological properties.
- Cellulose fine fiber B Cellulose fine fiber B (MFC-B) was obtained in the same manner as cellulose fine fiber A, except that the number of treatments with the single disc refiner (second stage) was changed to 30 times. Table 6 shows the results of analysis of various fiber shape parameters and rheological properties.
- linter pulp which is a natural cellulose obtained from Japan Pulp & Paper Co., Ltd.
- the linter pulp is immersed in water so that the linter pulp is 1.5% by mass, and is easily dispersed using a lab pulper (manufactured by Aikawa Iron Works). After that, the liquid was sent to the tank.
- a single disk refiner previously stage equipped with a disk with a blade width of 2.5 mm, a groove width of 7.0 mm, and a blade groove ratio of 0.36 connected to the tank was used to refine the slurry while circulating it. .
- the operation was started from a blade-to-blade distance of 1.0 mm, and the blade-to-blade distance was gradually reduced to a final blade-to-blade distance of 0.3 mm.
- the operation was continued while checking the flow rate, and the operation was terminated when the entire amount of the slurry had passed through the disk portion 90 times.
- a single disk refiner (later stage) equipped with a disk having a blade width of 0.8 mm, a groove width of 1.5 mm, and a blade groove ratio of 0.53 was used to refine the slurry while circulating it.
- cellulose fine fiber C (MFC-C). Table 6 shows the results of analysis of various fiber shape parameters and rheological properties.
- Cellulose fine fiber D Cellulose fine fibers C are finely treated 10 times at an operating pressure of 100 MPa using a high-pressure homogenizer (NS015H manufactured by Nilo Soavi (Italy)), and the resulting cellulose fine fibers are cellulose fine fibers D (MFC-D). and Table 6 shows the results of analysis of various fiber shape parameters and rheological properties.
- linter pulp which is a natural cellulose obtained from Japan Pulp & Paper Co., Ltd.
- the linter pulp is immersed in water so that the linter pulp is 1.5% by mass, and is easily dispersed using a lab pulper (manufactured by Aikawa Iron Works). After that, the liquid was sent to the tank.
- a single disk refiner previously stage equipped with a disk with a blade width of 2.5 mm, a groove width of 7.0 mm, and a blade groove ratio of 0.36 connected to the tank was used to refine the slurry while circulating it. .
- linter pulp which is a natural cellulose obtained from Japan Pulp & Paper Co., Ltd.
- the linter pulp is immersed in water so that the linter pulp is 1.5% by mass, and is easily dispersed using a lab pulper (manufactured by Aikawa Iron Works). After that, the liquid was sent to the tank.
- a single disk refiner (only one unit) equipped with a disk with a blade width of 2.5 mm, a groove width of 7.0 mm, and a blade groove ratio of 0.36, connected to the tank, refines the slurry while circulating it. provided.
- linter pulp which is a natural cellulose obtained from Japan Pulp & Paper Co., Ltd.
- the linter pulp is immersed in water so that the linter pulp is 1.5% by mass, and is easily dispersed using a lab pulper (manufactured by Aikawa Iron Works). After that, the liquid was sent to the tank.
- a single disk refiner previously stage equipped with a disk with a blade width of 2.5 mm, a groove width of 7.0 mm, and a blade groove ratio of 0.36 connected to the tank was used to refine the slurry while circulating it. .
- linter pulp which is a natural cellulose obtained from Japan Pulp & Paper Co., Ltd.
- the linter pulp is immersed in water so that the linter pulp is 1.5% by mass, and is easily dispersed using a lab pulper (manufactured by Aikawa Iron Works). After that, the liquid was sent to the tank.
- a single disk refiner (only one unit) equipped with a disk with a blade width of 0.8 mm, a groove width of 1.5 mm, and a blade groove ratio of 0.53, connected to the tank, refines the slurry while circulating it. provided.
- cellulose fine fiber H (MFC-H). Table 6 shows the results of analysis of various fiber shape parameters and rheological properties.
- linter pulp which is a natural cellulose obtained from Japan Pulp & Paper Co., Ltd.
- the linter pulp is immersed in water so that the linter pulp is 1.5% by mass, and is easily dispersed using a lab pulper (manufactured by Aikawa Iron Works). After that, the liquid was sent to the tank.
- a single disk refiner (previous stage) equipped with a disk with a blade width of 4.0 mm, a groove width of 4.5 mm, and a blade groove ratio of 0.89 connected to the tank was used to refine the slurry while circulating it. .
- cellulose fine fiber I (MFC-I). Table 6 shows the results of analysis of various fiber shape parameters and rheological properties.
- Cellulose fine fiber J Cellulose fine fiber J (MFC-J) was obtained in the same manner as for cellulose fine fiber A (MFC-A), except that the number of treatments with the single disc refiner (second stage) was changed to 180 times. Table 6 shows the results of analysis of various fiber shape parameters and rheological properties.
- linter pulp which is a natural cellulose obtained from Japan Pulp & Paper Co., Ltd.
- the linter pulp is immersed in water so that the linter pulp is 1.5% by mass, and is easily dispersed using a lab pulper (manufactured by Aikawa Iron Works). After that, the liquid was sent to the tank.
- a single disk refiner (only one unit) equipped with a disk with a blade width of 4 mm, a groove width of 4.5 mm, and a blade groove ratio of 0.89 connected to the tank was used to refine the slurry while circulating it. .
- linter pulp which is a natural cellulose obtained from Japan Pulp & Paper Co., Ltd.
- the linter pulp is immersed in water so that the linter pulp is 1.5% by mass, and is easily dispersed using a lab pulper (manufactured by Aikawa Iron Works). After that, the liquid was sent to the tank.
- a single disk refiner (only one unit) equipped with a disk with a blade width of 2.5 mm, a groove width of 7.0 mm, and a blade groove ratio of 0.36, connected to the tank, refines the slurry while circulating it. provided.
- the operation was started from a blade-to-blade distance of 1.0 mm, and the blade-to-blade distance was gradually reduced to a final blade-to-blade distance of 0.3 mm. After the distance between the blades reached 0.3 mm, the operation was continued while checking the flow rate, and the operation was terminated when the entire amount of the slurry had passed through the disk portion 90 times.
- the resulting cellulose fine fibers were designated as microfibrillated cellulose L (MFC-L).
- Table 6 shows the results of analysis of various fiber shape parameters and rheological properties.
- ⁇ Manufacturing of fiber reinforced resin ⁇ (Example II-1-1) Using MFC-A as cellulose fine fibers, a composite was produced by injection molding in the following procedure. 1. The cellulose fine fibers were concentrated by suction filtration (filter medium: TT35 manufactured by Shikishima Canvas Co., Ltd.) to obtain a wet cake having a solid content of about 20% by mass. 2. The wet cake is added to hexafluoroisopropanol (hereinafter referred to as HFIP) to a final concentration of 1% by volume using a homogenizer (manufactured by IKA, trade name "Ultra Turrax T18”) at a rotation speed of 12,000 rpm. Dispersion treatment was performed for 3 minutes. 3.
- a homogenizer manufactured by IKA, trade name "Ultra Turrax T18
- a solution was prepared by dissolving polyamide 6 (manufactured by Ube Industries, 1013B, melting point 225° C.) in HFIP at 1% by mass. 4. Place 2 and 3 in the same container so that the solid content mass ratio of MFC-A and polyamide 6 is 1:9, and rotate at 2,000 rpm with a rotation / revolution mixer (Awatori Mixer ARE-310, manufactured by Thinky). and mixed for 5 minutes. 5. 4 was cast into a film on a release film (Mitsui Chemicals Tohcello, X88B) and dried in an oven at 80° C. for 1 hour. 6. 5 was pulverized with a desktop pulverizer (Mini Speed Mill MS-05 manufactured by Labnext). 7.
- Table 6 shows the results of evaluating Composite 1-A by the aforementioned tensile test and dynamic viscoelasticity measurement.
- Example II-1-2 A composite was produced in the same manner as in Example II-1-1, except that MFC-B was used as the cellulose fine fibers, to obtain Composite 1-B.
- Table 6 shows the results of evaluation of the resulting composite 1-B by the tensile test and dynamic viscoelasticity measurement described above.
- Example II-1-3 A composite was prepared in the same manner as in Example II-1-1, except that MFC-C was used as the cellulose fine fibers, to obtain Composite 1-C.
- Table 6 shows the results of evaluating the obtained composite 1-C by the tensile test and dynamic viscoelasticity measurement described above.
- Example II-1-4 A composite was prepared in the same manner as in Example II-1-1, except that MFC-D was used as the cellulose fine fibers, to obtain Composite 1-D.
- Table 6 shows the results of evaluating the obtained composite 1-D by the tensile test and dynamic viscoelasticity measurement described above.
- Example II-1-5 A composite was prepared in the same manner as in Example II-1-1, except that MFC-E was used as the cellulose fine fibers, to obtain Composite 1-E.
- Table 6 shows the results of evaluating the obtained composite 1-E by the tensile test and dynamic viscoelasticity measurement described above.
- Example II-1-6 A composite was prepared in the same manner as in Example II-1-1, except that MFC-F was used as the cellulose fine fiber, to obtain Composite 1-F.
- Table 6 shows the results of evaluating the obtained composite 1-F by the tensile test and dynamic viscoelasticity measurement described above.
- Example II-1-7 A composite was prepared in the same manner as in Example II-1-1, except that MFC-G was used as the cellulose fine fibers, to obtain Composite 1-G.
- Table 6 shows the results of evaluating the obtained composite 1-G by the tensile test and dynamic viscoelasticity measurement described above.
- Example II-1-8 A composite was prepared in the same manner as in Example II-1-1, except that MFC-H was used as the cellulose fine fibers, to obtain Composite 1-H.
- Table 6 shows the results of evaluating the obtained composite 1-H by the tensile test and dynamic viscoelasticity measurement described above.
- Example II-1-9 A composite was prepared in the same manner as in Example II-1-1, except that MFC-I was used as the cellulose fine fibers, to obtain Composite 1-I.
- Table 6 shows the results of evaluating the obtained composite 1-I by the tensile test and dynamic viscoelasticity measurement described above.
- Example II-1-1 A composite was prepared in the same manner as in Example II-1-1, except that MFC-J was used as the cellulose fine fibers, to obtain Composite 1-J.
- Table 6 shows the results of evaluating the obtained composite 1-J by the tensile test and dynamic viscoelasticity measurement described above.
- Example II-1-2 A composite was prepared in the same manner as in Example II-1-1, except that MFC-K was used as the cellulose fine fibers, to obtain Composite 1-K.
- Table 6 shows the results of evaluating the obtained composite 1-K by the tensile test and dynamic viscoelasticity measurement described above.
- Example II-1-3 A composite was prepared in the same manner as in Example II-1-1, except that MFC-L was used as the cellulose fine fibers, to obtain Composite 1-L.
- Table 6 shows the results of evaluating the obtained composite 1-L by the tensile test and dynamic viscoelasticity measurement described above.
- Example II-2-1 Polypropylene short fibers (cut length: 2.0 mm, fineness: 0.2 T, melting point: 160 ° C.) and MFC-A are added to pure water so that the solid content mass ratio is 80:20, and the solid content is The final concentration was 0.5% by mass.
- a papermaking slurry was prepared by stirring the slurry for 4 minutes with a household mixer. The papermaking slurry prepared above was applied to a batch-type paper machine (manufactured by Kumagai Riki Kogyo Co., Ltd., automatic square sheet machine 25 cm x 25 cm, 80 mesh) set with a filter cloth (TT35 manufactured by Shikishima Canvas Co., Ltd.) to a basis weight of 300 g/m 2 . After that, paper making (dehydration) was performed at a pressure reduction degree of 50 KPa with respect to the atmospheric pressure.
- the wet paper web consisting of the wet concentrated composition on the resulting filter cloth was peeled off from the wire and pressed at a pressure of 1 kg/cm 2 for 1 minute. After that, it was dried for about 120 seconds with a drum dryer whose surface temperature was set to 130° C. to obtain a nonwoven fabric S1, which is a wet-laid nonwoven fabric.
- a drum dryer whose surface temperature was set to 130° C. to obtain a nonwoven fabric S1, which is a wet-laid nonwoven fabric.
- Four nonwoven fabrics of 10 cm square were cut out from the obtained nonwoven fabric S1 and laminated, which was sandwiched between PET films having a thickness of 0.1 ⁇ m. This was press molded for 5 minutes at a temperature of 200° C. and a molding pressure of 10 kg/cm 2 using a hot press.
- the thickness of the molding was controlled by providing a 1.5 mm spacer made of stainless steel between the PET films. After that, the heating of the hot press was terminated, and the entire press was gradually cooled with an air blower over about 30 minutes while maintaining the pressure. When the temperature of the press reached 90° C. or lower, the pressure was released to obtain a plate-shaped composite 2-A. Table 7 shows the results of evaluating the obtained composite 2-A by the bending test described above.
- Example II-2-2 A composite was prepared in the same manner as in Example II-2-1, except that MFC-B was used as the cellulose fine fibers, to obtain Composite 2-B.
- Table 7 shows the results of evaluating the obtained composite 2-B by the bending test described above.
- Example II-2-3 A composite was produced in the same manner as in Example II-2-1, except that MFC-C was used as the cellulose fine fibers, to obtain Composite 2-C.
- Table 7 shows the results of evaluating the obtained composite 2-C by the bending test described above.
- Example II-2-4 A composite was prepared in the same manner as in Example II-2-1, except that MFC-D was used as the cellulose fine fibers, to obtain Composite 2-D.
- Table 7 shows the results of evaluating the obtained composite 2-D by the bending test described above.
- Example II-2-5 A composite was prepared in the same manner as in Example II-2-1, except that MFC-E was used as the cellulose fine fibers, to obtain Composite 2-E.
- Table 7 shows the results of evaluating the obtained composite 2-E by the bending test described above.
- Example II-2-6 A composite was prepared in the same manner as in Example II-2-1, except that MFC-F was used as the cellulose fine fiber, to obtain Composite 2-F.
- Table 7 shows the results of evaluating the obtained composite 2-F by the bending test described above.
- Example II-2-7 A composite was prepared in the same manner as in Example II-2-1, except that MFC-G was used as the cellulose fine fibers, to obtain Composite 2-G.
- Table 7 shows the results of evaluating the obtained composite 2-G by the bending test described above.
- Example II-2-8 A composite was prepared in the same manner as in Example II-2-1, except that MFC-H was used as the cellulose fine fibers, to obtain Composite 2-H.
- Table 7 shows the results of evaluating the obtained composite 2-H by the bending test described above.
- Example II-2-9 A composite was prepared in the same manner as in Example II-2-1, except that MFC-I was used as the cellulose fine fibers, to obtain Composite 2-I.
- Table 7 shows the results of evaluating the obtained composite 2-I by the bending test described above.
- Example II-2-10 Using MFC-A as cellulose fine fibers, a composite was produced by injection molding in the following procedure. 1. Polypropylene short fibers (cut length: 2.0 mm, fineness: 0.2 T, melting point: 160°C) are placed on a release film (Mitsui Chemicals Tohcello, X88B) and heated in an oven at 200°C to melt. rice field. 2. 1 was solidified by cooling, and pulverized with a desktop pulverizer (Mini Speed Mill MS-05, manufactured by Labnext). 3.
- Cellulose fine fibers and rosin ethylene oxide adduct (Rosin-polyethylene glycol, manufactured by Harima Kasei Co., Ltd.) are placed in a closed planetary mixer (manufactured by Kodaira Seisakusho Co., Ltd., trade name "ACM-5LVT", stirring blades are hook type).
- cellulose fine fiber/rosin ethylene oxide adduct in a mass ratio of 80/20, stirred at normal temperature and pressure at 70 rpm for 60 minutes, and finally reduced in pressure (-0.1 MPa), It was set in a hot bath at 40° C. and subjected to coating and vacuum drying treatment at 307 rpm for 2 hours to obtain a powdery cellulose fine fiber preparation A. 4.
- the powders of 2 and 3 were blended so that the mass ratio of cellulose fine fibers and polypropylene was 20:80, and mixed with a small kneader (manufactured by DSM, Xplore MC 15HT) at a temperature of 200°C and a rotation speed of 200 rpm. Knead for a minute. 5. After kneading, the kneaded product was poured into an injection molding machine (Xplore IM12) to prepare a strip-shaped test piece (10 mm ⁇ 75 mm ⁇ 4 mm) as a composite 2-A2.
- Xplore IM12 injection molding machine
- Table 7 shows the results of evaluating Composite 2-A2 by the bending test described above.
- Example II-2-1 A composite was prepared in the same manner as in Example II-2-1, except that MFC-J was used as the cellulose fine fibers, to obtain Composite 2-J.
- Table 7 shows the results of evaluating the obtained composite 2-J by the bending test described above.
- Example II-2-2 A composite was prepared in the same manner as in Example II-2-1, except that MFC-K was used as the cellulose fine fibers, to obtain Composite 2-K.
- Table 7 shows the results of evaluating the obtained composite 2-K by the bending test described above.
- Example II-2-3 A composite was produced in the same manner as in Example II-2-1, except that MFC-L was used as the cellulose fine fiber, to obtain Composite 2-L.
- Table 7 shows the results of evaluating the obtained composite 2-L by the bending test described above.
- Example II-2-4 A composite was produced in the same manner as in Example II-2-10, except that MFC-J was used as the cellulose fine fiber.
- the obtained composite was designated as composite 2-J2, and Table 7 shows the results of evaluation by the bending test described above.
- the cellulose fine fibers of the present invention provide a fiber-reinforced resin excellent in all of elastic modulus, strength, and breaking strain when mixed with a resin, and are used as reinforcing materials for resins used in automobiles, housing, home appliances, construction, etc. It can be suitably used as
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Abstract
Description
[1]
繊維形状自動分析計の測定において、
(i)繊維長100μm以上の繊維の長さ加重平均繊維長が、110μm以上500μm以下、
(ii)平均繊維径が42.5μm以下、
(iii)ファイン繊維面積比が90%以下、
(iv)繊維長100μm未満の繊維のうち、20μm以上56μm以下の繊維長を有する繊維の数頻度が97%以下、
(v)繊維長100μm以上の繊維のうち、繊維長が411μm以上である繊維の数頻度が54%以下、及び
(vi)比表面積で換算したときの平均繊維径が20~150nm、
のすべてを満たす、セルロース微細繊維。
[2]
平均繊維長が110μm以上500μm以下である、項目1に記載のセルロース微細繊維。
[3]
繊維形状自動分析計の測定において、
(i)平均繊維長が130μm以上350μm以下、
(ii)平均繊維径が35μm以下、
(iii)ファイン繊維面積比が75%以下、
(iv)繊維長100μm未満の繊維のうち、20μm以上56μm以下の繊維長を有する繊維の数頻度が75%以下、
(v)繊維長100μm以上の繊維のうち、411μm以上の繊維長を有する繊維の数頻度が30%以下、及び
(vi)フィブリル化率が5%以下、
のすべてを満たす、項目1又は2に記載のセルロース微細繊維。
[4]
構成糖分析におけるグルコース含有率が90質量%以上である、項目1~3のいずれかに記載のセルロース微細繊維。
[5]
セルロース微細繊維の5質量ppmDMSO分散液をキャスト及び乾燥して得た試料の表面の走査型電子顕微鏡(SEM)画像において、セルロース微細繊維の占める総面積に対する、占有面積が15μm2未満である極微小繊維の総占有面積の割合が10%以上80%以下である、項目1~4のいずれかに記載のセルロース微細繊維。
[6]
セルロースI型の結晶構造を有する、項目1~5のいずれかに記載のセルロース微細繊維。
[7]
結晶化度が60%以上である、項目1~6のいずれかに記載のセルロース微細繊維。
[8]
ハロゲン含有量が250質量ppm以下である、項目1~7のいずれかに記載のセルロース微細繊維。
[9]
白色度が50%以上である、項目1~8のいずれかに記載のセルロース微細繊維。
[10]
繊維長100μm以上の繊維の長さ加重平均繊維長が130μm以上350μm以下である、項目1~9のいずれかに記載のセルロース微細繊維。
[11]
繊維長が100μm以上の繊維のうち、繊維長が411μm以上である繊維の数頻度が30%以下である、項目1~10のいずれかに記載のセルロース微細繊維。
[12]
ファイン繊維面積比が75%以下である、項目1~11のいずれかに記載のセルロース微細繊維。
[13]
繊維長100μm未満の繊維のうち、20μm以上56μm以下の繊維長を有する繊維の数頻度が30%以上75%以下である、項目1~12のいずれかに記載のセルロース微細繊維。
[14]
フィブリル化率が5%以下である、項目1~13のいずれかに記載のセルロース微細繊維。
[15]
少なくとも表面が化学修飾されたセルロース微細繊維である、項目1~14のいずれかに記載のセルロース微細繊維。
[16]
化学修飾がアセチル化であり、アセチル化度が0.5~1.3である、項目15に記載のセルロース微細繊維。
[17]
繊維形状自動分析計の測定において
(iv)繊維長100μm未満の繊維のうち、20μm以上56μm以下の繊維長を有する繊維の数頻度が30%以上97%以下、及び
(vi)フィブリル化率が5%以下、
をさらに満たす、項目1~16のいずれかに記載のセルロース微細繊維。
[18]
項目1~17のいずれかに記載のセルロース微細繊維の製造方法であって、
前記セルロース微細繊維のハロゲン含有量が250質量ppm以下であり、前記方法が、
ハロゲン含有量が300質量ppm以下であるセルロース原料を解繊する工程を含む、セルロース微細繊維の製造方法。
[19]
項目1~17のいずれかに記載のセルロース微細繊維と、樹脂とを含む、繊維強化樹脂。
[20]
前記樹脂が融点200℃以上を有する、項目19に記載の繊維強化樹脂。
[21]
前記セルロース微細繊維1質量%以上を含む、項目19又は20に記載の繊維強化樹脂。
[22]
項目1~17のいずれかに記載のセルロース微細繊維を含む、不織布。
[23]
融点300℃以下の合成繊維を50質量%以上含む、項目22に記載の不織布。
[24]
前記セルロース微細繊維を1質量%以上含む、項目22又は23に記載の不織布。
[25]
項目22~24のいずれかに記載の不織布と前記不織布に含浸されている樹脂とを含む、繊維強化樹脂。
[26]
セルロース微細繊維と樹脂とを含む繊維強化樹脂の製造方法であって、
項目22~24のいずれかに記載の不織布を熱プレスして繊維強化樹脂を得る工程を含み、
前記不織布が合成繊維を含み、前記熱プレスを、前記合成繊維の融点以上で行う、繊維強化樹脂の製造方法。
<セルロース微細繊維の形状>
一態様に係るセルロース微細繊維は、繊維形状自動分析計の測定において、
(i)繊維長100μm以上の繊維の長さ加重平均繊維長が、110μm以上500μm以下、
(ii)平均繊維径が42.5μm以下、
(iii)ファイン繊維面積比が90%以下、
(iv)繊維長100μm未満の繊維のうち、20μm以上56μm以下の繊維長を有する繊維の数頻度が97%以下、及び
(v)繊維長100μm以上の繊維のうち、411μm以上の繊維長を有する繊維の数頻度が54%以下、
のすべてを満たす。
(i)平均繊維長が130μm以上350μm以下、
(ii)平均繊維径が35μm以下、
(iii)微細繊維面積比が75%以下、
(iv)繊維長100μm未満の繊維のうち、20μm以上56μm以下の繊維長を有する繊維の数頻度が75%以下、
(v)繊維長100μm以上の繊維のうち、411μm以上の繊維長を有する繊維の数頻度が30%以下、及び
(vi)フィブリル化率が5%以下、
のすべてを満たす。
(1)平均繊維径が42.5μm以下、
(2)ファイン繊維面積比が90%以下、
(3)繊維長100μm未満の繊維のうち、20μm以上56μm以下の繊維長を有する繊維の数頻度が30%以上97%以下、及び
(4)フィブリル化率が5%以下、
を満たすことが好ましい。
本実施形態におけるセルロース微細繊維の種々の特徴は繊維形状自動分析計(一態様においてTechpap社製Morfi Neo)を用いて行う。以下に測定手順を説明する。尚、測定の際の繊維パラメータは繊維長100μmを閾値とし、繊維長100μm以上の繊維を通常繊維、繊維長100μm未満の繊維をファイン繊維と定義する。
1. セルロース微細繊維を純水に分散し、1Lの水分散体を用意する。ここで、セルロース微細繊維の固形分終濃度は0.003~0.005質量%とする。なお、希釈前のセルロース微細繊維が2質量%未満の水分散体である場合には、スパチュラ等で簡易的に混ぜるだけで良いが、2質量%以上の水分散体、含水ケーク若しくは粉末状等である場合においては、高せん断ホモジナイザー(一態様においてIKA製、商品名「ウルトラタラックスT18」)を用い処理条件:回転数25,000rpm×5分間で分散処理を行う。水以外の媒体に分散されている場合、上記高せん断ホモジナイザーを用い処理条件:回転数25,000rpm×5分間で、充分量の純水中に分散処理を行ったのち、吸引濾過等の手段で、媒体を除去、再度、上記高せん断ホモジナイザーを用い純水中に、処理条件:回転数25,000rpm×5分間で、固形分終濃度0.003~0.005質量%となるように分散処理を行うことで、媒体を水に置換する。
2. 1.で調製した水分散体をオートサンプラーに供し、測定を行う。
3. 測定結果をtxt形式(又はcsv形式)で出力する。
4. 測定結果より各形状パラメータを抽出、又は算出する。なお、各パラメータは測定結果のうち次の値を利用するものとする。
(2)通常繊維(繊維長100μm以上の繊維)における長さ加重平均繊維長:Mean length-weighted Length[μm]
(3)通常繊維(繊維長100μm以上の繊維)における繊維長411μm以上の繊維の数頻度:通常繊維の長さ加重繊維長分布(length-weighted Fiber lemgth,μm) より算出する。
(4)平均繊維径:Mean fiber width[μm]
(5)ファイン繊維面積比:Fine content,% in Area
(6)ファイン繊維(繊維長100μm未満の繊維)における繊維長20μm以上56μm以下の繊維の数頻度:ファイン繊維の繊維長分布(Fine length、μm:FL)より算出する。
(7)フィブリル化率:MacroFibrillation index[%]
一態様に係るセルロース微細繊維は、繊維形状自動分析計における、平均繊維長が、110μm以上500μm以下、又は130μm以上350μm以下である。ここで平均繊維長は、算術平均繊維長(Mean Arithmetic fiber length)であり、屈折した繊維においては、その端部同士を直線で結んだ長さを意味する。平均繊維長がこの範囲であることで、樹脂に配合した際に均一分散でき、応力伝達性が向上するため、強度、破壊歪が大きくなる。セルロース微細繊維の平均繊維長は好ましくは150μm以上250μm以下であり、より好ましくは160μm以上200μm以下である。
一態様に係るセルロース微細繊維は、繊維形状自動分析計での測定において、通常繊維(繊維長100μm以上の繊維)の長さ加重平均繊維長が110μm以上500μm以下、より好ましくは120μm以上400μm以下、さらに好ましくは130μm以上350μm以下である。長さ加重平均繊維長はISO/FDIS 16065-2:2006に定義されており、屈折した繊維においてはその屈折形状を考慮した実際の繊維長に相当する繊維長の平均値である。セルロース微細繊維のうち特に通常繊維の繊維長を特定範囲に制御することが有利である。すなわち、通常繊維の繊維長がこの範囲にあることで、樹脂に配合した際に長すぎる繊維同士が絡まって凝集体を形成することがなく均一に分散でき、応力伝達性が向上するため、強度、及び破壊歪が大きくなる。
一態様に係るセルロース微細繊維は、繊維形状自動分析計での測定において、通常繊維(繊維長100μm以上の繊維)のうち、繊維長が411μm以上の繊維の数頻度が54%以下である。当該数頻度は、上記長さ加重繊維長分布から計算できる。長さ加重繊維長は、屈折した繊維においてはその屈折形状を考慮した実際の繊維長に相当する繊維長である。通常繊維の繊維長がこの範囲にあることで、樹脂に配合した際に長すぎる繊維同士が絡まって凝集体を形成することがなく均一に分散でき、応力伝達性が向上するため、強度、及び破壊歪が大きくなる。通常繊維のうち、繊維長が411μm以上の繊維の数頻度は、好ましくは40%以下であり、より好ましくは30%以下である。下限は特に限定されず0%以上である。
本実施形態のセルロース微細繊維は、繊維形状自動分析計における平均繊維径が、好ましくは、42.5μm以下、又は41.5μm以下、又は40μm以下、又は38μm以下、又は35μm以下、又は30μm以下、又は25μm以下である。長さ加重平均繊維長、及び/又は平均繊維長が上記範囲であるとともに平均繊維径がこの範囲であることは、個々のセルロース微細繊維のL/Dが十分に大きいことを意味する。L/Dが大きくなることで、樹脂中でセルロース微細繊維同士が絡み合いを生じる為、繊維強化樹脂の強度を高めることができる。繊維径は、細い方が、L/Dが大きくなるため好ましいが、測定装置の分解能上、1.5μm以上であってよい。また、繊維強化樹脂の曲げ弾性を高くするにはある程度以上の太さが有利であるという観点からは、15μm以上が好ましい。
セルロース微細繊維において、比表面積は一態様では平均繊維径に概ね対応しており、平均繊維径が小さくなると比表面積は大きくなる。一態様において、比表面積は、繊維強化樹脂の強度を高める観点から、好ましくは20m2/g以上、又は30m2/g以上、又は40m2/g以上であり、繊維強化樹脂の曲げ弾性を高める観点から、好ましくは、100m2/g以下、又は80m2/g以下、又は60m2/g以下である。
本実施形態のセルロース微細繊維は、繊維形状自動分析計における、ファイン繊維面積比が、好ましくは、90%以下、又は85%以下、又は80%以下、又は75%以下、又は60%以下、又は50%以下である。ここで、ファイン繊維面積比とは、全繊維の観察像の面積総和(通常繊維の面積+ファイン繊維の面積)に占める、繊維長100μm未満であるファイン繊維の観察像の面積総和の比率である。ファイン繊維面積比がこの範囲にあることで、樹脂中でセルロース/樹脂間の脆弱な界面が多くなりすぎず、破壊の起点が少なくなるため、破壊歪が大きくなる。ファイン繊維面積比は、樹脂に配合した際に配向が生じやすく、繊維強化樹脂の強度及び弾性率の向上に良好な効果が得られる点で、好ましくは、5%以上、又は10%以上、又は20%以上、又は30%以上である。
本実施形態のセルロース微細繊維は、繊維形状自動分析計において、ファイン繊維(繊維長100μm未満の繊維)中に占める20μm以上56μm以下の繊維長を有する繊維の数頻度が、好ましくは、97%以下、又は90%以下、又は85%以下、又は80%以下、又は75%以下、又は70%以下、又は65%以下である。これらのファイン繊維は繊維長が短すぎる為、応力伝達性に乏しく、強度向上への寄与が小さい傾向がある。これらのファイン繊維の数頻度が所定の範囲で制御されることで特に有効な補強効果が得られる。20μm以上56μm以下の繊維長のファイン繊維は、セルロース原料の微細化処理に伴って少なからず生じるため、その数頻度は、一態様において、5%以上であってよく、一態様においては、30%以上、又は50%以上、又は55%以上、又は60%以上であってよい。
本実施形態のセルロース微細繊維は、繊維形状自動分析計における、フィブリル化率が、好ましくは5%以下である。ここでフィブリル化率とは、少なくも一部が分岐した構造を有する繊維において、最も径が大きい部分を主鎖として、その主鎖長L(Main)に対する、分岐したn本の側鎖L(Sub)の合計長さの比率であり、以下の式で定義される。
セルロース微細繊維を固形分5質量ppmジメチルスルホキキド(DMSO)分散液とし、それを平滑な基板上にキャスト及び乾燥して得られた試料の表面の走査型電子顕微鏡(SEM)撮影画像において、セルロース微細繊維の占める総面積に対する、占有面積が15μm2以下である極微小繊維の総占有面積の割合、すなわち極微小繊維の占有面積比率は、10%以上80%以下であることが好ましい。この極微小繊維は、繊維形状自動分析計では素子の分解能により測定できない領域の繊維であり、この極微小繊維の占有面積比率が大きすぎると、ナノサイズの繊維が多すぎることから樹脂中での極微小繊維の凝集が起きやすくなり、破壊の起点となってしまう場合がある。一方、極微小繊維の占有面積比率が小さすぎると、ナノサイズの繊維が少なすぎることから良好なナノネットワークが得られず強度が低い傾向がある。上記観点から、極微小繊維の占有面積比率は、より好ましくは15%以上75%以下、より好ましくは20%以上70%以下、最も好ましくは20%以上65%以下である。極微小繊維の占有面積比率が上記範囲であるセルロース微細繊維は、少なくとも1種類の物理的な手法を用いて微細化されたものであってよく、一般的にはセルロースナノファイバー、CNF、CeNF、微細化セルロース微細繊維などと呼称される。極微小繊維の占有面積比率は以下の手順で測定する。
2.平滑な基板(シリコンウエハーやガラス基板)にオスミウムプラズマコーティングを施し、ホットプレート上で130℃に加熱する。
3.加熱した平滑な基板の中央にDMSO分散液を7μL滴下し、加熱下で静置乾燥させ、セルロース微細繊維を基板上に固定する。
4.得られたセルロース微細繊維を固定した基板を走査型電子顕微鏡(SEM)にて、加速電圧1.5kV、観察倍率400倍、100μm当たり400ピクセル以上の解像度で基板上の任意の異なる場所で4枚画像を撮影する。
5.SEM画像のスケールバーのピクセル数から閾値である15μm2に相当するピクセル数を算出する。
6.取得したSEM画像から、画像処理ソフトウェアImageJを用いて、MaxEntropy法で二値化像を作成する。
7.二値化像をImageJのAnalyze Particleを用いて粒子解析し、セルロース微細繊維の単繊維の面積(ピクセル)を算出する。
8.撮影した4画像の粒子解析結果を合算し、2ピクセル以下をノイズとして削除し、閾値として面積15μm2未満を極微小繊維とし、セルロース微細繊維の総面積に占める15μm2未満の極微小繊維の面積の比率を算出する。
本実施形態のセルロース微細繊維の特異な繊維形状、より具体的には、一態様において、通常繊維の長さ加重繊維長、平均繊維長、平均繊維径、ファイン繊維面積比、ファイン繊維繊維長、フィブリル化率、及び/又は極微小繊維の占有面積比率、が本実施形態の範囲内となるような繊維形状、又は、一態様において、平均繊維長、平均繊維径、微細繊維面積比(極微小繊維の占有面積比率)、繊維長100μm未満の繊維のうち20μm以上56μm以下の繊維長を有する繊維の数頻度、繊維長100μm以上の繊維のうち411μm以上の繊維長を有する繊維の数頻度、及び/又はフィブリル化率、が本実施形態の範囲内となるような繊維形状、を実現する方法としては、例えば以下に例示する手法のうち1つ以上を用いることが挙げられる。セルロース原料の微細化に際してディスクリファイナーを用いること、より具体的には、当該ディスクリファイナーのディスク構成及び/又は使用条件を調整することは、本実施形態の所望の繊維形状の実現に特に有利であり得る。
セルロース微細繊維の原料としては、特に限定されず、木材系セルロース原料(例えば、針葉樹チップ、及び広葉樹チップ)、或いは非木材系セルロース原料(コットン由来、麻由来、バガス由来、ケナフ由来、竹由来、ワラ由来、海藻由来、藻類由来、ホヤ由来及びバクテリアセルロース由来など)が使用できる。針葉樹パルプ、広葉樹パルプ等のいわゆる木材パルプ、及び、コットンリンターパルプ、麻パルプ、バガスパルプ、ケナフパルプ、竹パルプ、及びワラパルプ等の非木材パルプなどの、I型結晶化度の高いセルロース原料を用いることが好ましい。好ましい態様において、セルロース微細繊維は植物由来である。
上述のセルロース原料の繊維長は、繊維形状自動分析計(Techpap社製Morfi Neo)を用いて測定できる。以下に測定手順を説明する。
2)繊維長3mm以上の繊維の割合:1)の繊維長分布のヒストグラムから、全繊維に占める繊維長3mm以上の繊維の本数の割合を以下の式から算出する。
繊維長3mm以上の繊維の割合(%)=繊維長3mm以上の繊維の本数/全測定本数x100
3)平均繊維径:Mean fiber width[μm]
本実施形態のセルロース原料は、その繊維長を特定の範囲に制御するために、粉砕、磨砕、及び分級から選ばれる1つ以上前処理を施された後、解繊(例えば叩解処理)に用いてよい。一態様に係る前処理は、平均繊維長が3mm超であり、且つ繊維長3mm以上の繊維の数割合が20%超であるセルロース原料から、平均繊維長が3mm以下、及び/又は、繊維長3mm以上の繊維の数割合が20%以下である前処理済セルロース原料を生成する処理である。
一態様において、セルロース原料及び/又はセルロース微細繊維は、セルロースI型の結晶構造を有し、又はセルロースII型の結晶構造を有してよい。好ましい態様において、セルロース微細繊維は、セルロースI型の結晶構造を有する。本実施形態のセルロース原料又はセルロース微細繊維の結晶化度は、55%以上、又は60%以上であることが好ましい。結晶化度がこの範囲にあると、セルロース微細繊維自体の力学物性(特に強度と寸法安定性)が高まるため、セルロース微細繊維を樹脂に分散して成る繊維強化樹脂の強度及び寸法安定性が高くなる傾向にある。セルロース原料又はセルロース微細繊維の結晶化度は、好ましくは65%以上であり、さらに好ましくは70%以上であり、最も好ましくは80%以上である。結晶化度は高いほど好ましい傾向にあるため上限は特に限定されないが、生産上の観点から99%が好ましい上限である。
結晶化度(%)=[I(200)-I(amorphous)]/I(200)×100
I(200):セルロースI型結晶における200面(2θ=22.5°)による回折ピーク強度
I(amorphous):セルロースI型結晶におけるアモルファスによるハローピーク強度であって、200面の回折角度より4.5°低角度側(2θ=18.0°)のピーク強度
結晶化度(%) =h1 /h0 ×100
本実施形態のセルロース微細繊維は、セルロース微細繊維表面の水酸基を化学修飾により変性したセルロース微細繊維であり、解繊前の状態(一態様においてパルプの状態)で化学修飾してから後述の微細化処理を行っても良く、微細化処理を行いセルロース微細繊維とした後で化学修飾しても良い。低ハロゲンセルロース微細繊維を得る場合には、解繊前の状態で化学修飾し、次いで後述の解繊処理を施すことが好ましい。また、解繊前に前処理を行う場合、この化学修飾は、前処理前に施すことも可能であるが、前処理後に施す方が容易であり好ましい。
置換度DS = 4.13 × IRインデックス(1030)
を使用することで求めることができる。
DS=(Inf)×6/(Inp)
たとえば、修飾基がアセチル基の場合、-CH3に帰属される23ppmのシグナルを用いれば良い。
装置 :Bruker Biospin Avance500WB
周波数 :125.77MHz
測定方法 :DD/MAS法
待ち時間 :75sec
NMR試料管 :4mmφ
積算回数 :640回(約14Hr)
MAS :14,500Hz
化学シフト基準:グリシン(外部基準:176.03ppm)
セルロース繊維は、一態様において、表面が化学修飾されたセルロース微細繊維であってよい。一態様においては、化学修飾セルロース微細繊維の繊維全体の置換度(DS)に対する繊維表面の置換度(DSs)の比率で定義されるDS不均一比(DSs/DS)が、1.05以上である。
DSs=(Ixf)×5/(Ixp)
化学修飾基がアセチル基の場合、C1sスペクトルを285eV、286eV,288eV,289eVでピーク分離を行った後、Ixpには289evのピークを、Ixfにはアセチル基のO-C=O結合由来のピーク(286eV)を用いれば良い。
用いるXPS測定の条件は例えば以下の通りである。
使用機器 :アルバックファイVersaProbeII
励起源 :mono.AlKα 15kV×3.33mA
分析サイズ :約200μmφ
光電子取出角 :45°
取込領域
Narrow scan:C 1s、O 1s
Pass Energy:23.5eV
本実施形態の化学修飾においては、攪拌条件、温度等は適宜調整されるものであるが、化学修飾前後のセルロース原料又はセルロース微細繊維の繊維長の維持率(繊維長の維持率(%)=修飾後の平均繊維長(nm)/修飾前の平均繊維長(nm)x100)は、70%以上であることが好ましく、80%以上であることがより好ましく、90%以上であることが特に好ましい。ここでいう平均繊維長は、繊維形状自動分析計(Techpap社製Morfi Neo)を用いて測定される長さ加重平均繊維長のことである。化学修飾後も繊維長が長く維持される場合、得られるセルロース微細繊維の繊維長が長く保たれることになるため、セルロース微細繊維を樹脂と複合化して得られる樹脂組成物の強度アップ、及び耐熱性アップにも有利である。繊維長の維持率は、高いほど効果が大きくなるため上限は特に限定されないが、現実的な修飾処理を想定すると99.5%以下が好ましい。
上記のような原料を微細化してセルロース微細繊維を得ることができる。微細化処理においては、原料パルプシート等をパルパーなどを用いて水に分散させ、ビーター、ディスクリファイナー、高圧ホモジナイザー、ウォータージェット、ディスクミル、ボールミル、ビーズミル、マスコロイダー、ホモミキサーなどの微細化装置を用いて微細化させる。一態様において、微細化は叩解処理であってよい。微細化処理は1段(1種類の刃で処理)で行っても、多段(複数種の刃で処理)で行っても良く、多段で行う場合は同じ装置を複数回使用してもよく、異なる装置を組み合わせて使用してもよい。一態様においては、多段が好ましい。
セルロースを多段で微細化する場合においては、微細化機構、又は剪断速度の異なる2種類以上の微細化装置を組み合わせることが有効である。ここで、多段微細化の方法としては、ディスク構成の異なるディスクリファイナーを用いて多段微細化すること、若しくはディスクリファイナーでの微細化後に高圧ホモジナイザーで微細化を行うことが好ましい。ここでディスクリファイナーには、シングルディスクリファイナー、ダブルディスクリファイナー、コニカルリファイナーのいずれを用いても構わない。一態様においては、微細化を高度に制御するために、固定刃と回転刃との間のクリアランス制御性が高いシングルディスクリファイナーが好ましい。
ディスクリファイナーを用いて微細化処理する場合、パルプ又は綿状のセルロース繊維(例えば精製セルロース繊維)を水媒体中に例えば0.5質量%以上6質量%以下、好ましくは0.8質量%以上3.5質量%以下、より好ましくは1質量%以上3質量%以下の固形分濃度となるようにタンク内にて分散、貯留し、ディスクリファイナーを用いて微細化させる。この際に使用する水は蒸留水やイオン交換水などの純度の高い水を用いると有効であることがある。
また、図3を参照し、ディスクリファイナーでの微細化においては、二つの刃(具体的には図3中の回転刃21及び固定刃22)の刃間距離WL(クリアランス)(以下、単に刃間距離と呼ぶ)を制御することが有利である。刃間距離を制御することで、セルロース微細繊維の繊維長や叩解の程度を制御することが可能である。多段で処理する場合、前段の処理においては、刃間距離を0.05mm以上、0.5mm以下、後段の処理においては刃間距離を0.05mm以上、0.3mm以下とすることが好ましい。また、1段で処理する場合は、刃間距離を0.05mm以上、0.3mm以下とすることが好ましい。尚、刃間距離を調整する際には、広目の刃間距離から装置の電流値を一定以下に抑えながら徐々に刃間を詰めていくことが好ましく、このように制御することで、装置の詰まりやオーバーロードを防止し、また、均質性の高いセルロース微細繊維が得られる。
微細化の程度は、セルロース微細繊維がディスク部分、すなわち回転刃と固定刃の間を通過する回数(以下、パス回数と呼ぶ)によっても制御可能である。パス回数を増加させることにより、繊維径、及び繊維長分布が均質なセルロース微細繊維を得ることができる。ここでバス回数とは、前記の刃間距離を目的の刃間距離に詰めてからのリファイナー処理を施した(すなわち回転場と固定場の間を通過した)回数を意味する。ディスクリファイナーのパス回数は、好ましくは5回以上、より好ましくは20回以上、さらに好ましくは40回以上である。回数を増やしていくと徐々に繊維形状の分布が一定に収束していくため多い方が好ましいが、生産性も考慮すると、パス数の上限としては300回以下が好ましい。
ディスクリファイナー処理によって得られるセルロース微細繊維の形状は、前述したディスクリファイナーの構成(刃の種類及び台数)、刃間距離、パス回数、濃度などの影響が複合的に作用して制御される。繊維強化樹脂に用いる際に好ましいセルロース微細繊維の形状を得るためには、比較的強度の低い処理条件においてパス回数を多くすることが好ましい。ここで処理の強度はディスクリファイナーの刃の構成と刃間距離によって決定される。刃の構成としては、刃幅、刃溝比が大きいと処理強度は低下し、小さいと処理強度は増大する。同様に刃間距離は、大きいと処理強度が低下し、小さいと処理強度は増大する。故に、処理強度の高い刃の構成とする場合、刃間距離を大きくすることが好ましく、逆に処理強度の低い刃の構成とする場合、刃間距離を小さくすることが好ましい。より好ましくは処理強度の高い刃の構成で刃間距離を大きくする方法であり、この処理条件において前述のパス回数とすることで平均繊維長及び繊維長の分布を好ましい範囲に制御することが可能である。一態様において、繊維強化樹脂に用いる際に好ましいセルロース微細繊維の形状を得るためには、粘状叩解条件においてパス数を多くすることが好ましい。粘状叩解とは、繊維を毛羽立たせて微細化していく傾向の叩解方法であり、繊維長方向の切断が生じる傾向の叩解方法は遊離叩解と呼ばれる。ディスクリファイナーの刃の構成として、刃の数が多く、刃長が長く、刃幅の溝幅に対する比(刃溝比)が大きく、接触角度が大きいほど、回転刃と固定刃のブレードの交錯数が増えるため、1つの交点で繊維に加わる力が分散し、繊維への衝撃回数が増加することで粘状叩解傾向を示す。一方、上記条件がそれぞれ逆の場合、遊離叩解傾向を示す。ディスクリファイナーの刃間距離は、遊離叩解傾向を示す刃を用いる場合は広げることが好ましく、粘状叩解傾向を示す刃を用いる場合は刃間距離を詰めることが好ましいが、刃間距離を詰めすぎると目詰まりや繊維長方向の切断による短繊維化、及び微細化されすぎることから、刃間距離は0.05mm以上であることが好ましい。セルロース原料(例えばパルプ)の形状(繊維長及び繊維径)、処理濃度、及び使用する刃により、前述の刃間距離及びパス回数を調整することで、平均繊維径及び繊維長分布等の繊維形状を好ましい範囲に制御することが可能である。
ここで、パス回数を制御する方法として、1台のリファイナーに対して、1台のタンクを用い、スラリーを単純に循環させ、流量に基づいてパス回数を制御する方法、又は、1台のリファイナーに対して2台のタンクを用い、スラリーをタンク間で往復させながらリファイナー処理する方法、などを用いてよい。前者においては設備の簡素化を図ることができる。一方で後者においては、毎回の処理において、セルロース微細繊維が確実にディスク部を通過するため、より均一性の高いセルロース微細繊維を得ることができる。樹脂に対する補強効果が良好である本実施形態のセルロース微細繊維、すなわち繊維形状が均一であるセルロース微細繊維を安定的に得る観点から、後者の方法が好ましい。
ディスクリファイナーで微細化されたセルロース微細繊維に対し、更に高圧ホモジナイザーによる微細化処理を施すことも好ましい様態の一つである。高圧ホモジナイザーはディスクリファイナーと比べ、繊維を細くする効果が大きい。ディスクリファイナーと高圧ホモジナイザーとを組み合わせることで、細長いセルロース微細繊維を得ることができる。高圧ホモジナイザー処理は、好ましくは30MPa以上、より好ましくは50MPa以上、より好ましくは80MPa以上の圧力で処理する。圧力の上限は装置の特性上、好ましくは300MPa以下、より好ましくは250MPa以下、より好ましくは150MPa以下であってよい。
一態様において、微細化処理の前に、前処理工程を経ても良い。前処理の方法としては、100~150℃の温度での水中含浸下でのオートクレーブ処理、酵素処理等、水酸化ナトリウム水溶液への浸漬、又はこれらの組合せなどが挙げられる。これらの前処理は、いずれもセルロースミクロフィブリル間の水素結合を破壊する作用を持ち、微細化処理の負荷を軽減するだけでなく、セルロース微細繊維を構成するミクロフィブリルの表面及び間隙に存在するリグニン、ヘミセルロース等の不純物成分を水相へ排出し、その結果、微細化された繊維のα-セルロース純度を高める効果もあるため、セルロース微細繊維の耐熱性の向上に有効であることもある。
本実施形態のセルロース微細繊維は、スラリーをろ過器や抄紙機などを用いて脱水し、湿潤成形体(湿潤ケーキ)として得ることができる。中でも抄紙機を用いた抄造法は、セルロース微細繊維同士の乾燥収縮を低減する点で有利である。一態様においては、スラリーを多孔質基材上で濾過することで脱水を行う。抄造法においては、スラリーを脱水し、セルロース微細繊維を留めるようなメッシュサイズのワイヤーを備える任意の抄紙機を使用できる。抄造装置としては、平坦シート形状の繊維強化樹脂を得る場合には、抄紙機として、傾斜ワイヤー式抄紙機、長網式抄紙機、円網式抄紙機のような装置を用いることができる。
本実施形態のセルロース微細繊維の、レオロジー特性としては、セルロース濃度0.75質量%とした水分散体の、歪分散測定において、降伏歪の逆数、1/γが200以上であることが好ましく、250以上であると、より好ましい。本パラメータがこの範囲であれば、セルロース微細繊維を樹脂に添加した際に、高温での動的粘弾性を改善する効果が大きい、すなわち、高温領域で貯蔵弾性率が高くなる。セルロース微細繊維は、繊維間の絡まり合いと、セルロース分子間に働く水素結合によって、水中で疑似的に架橋構造を形成していると言われており、水中におけるセルロース微細繊維間に働く相互作用は、樹脂中でのセルロース微細繊維間の相互作用を部分的に反映すると考えられる。一般に、ゲルなどの架橋体においては、架橋点間の距離、及び架橋の数が多いほど、架橋体の弾性率、及び強度は高くなると言われており、降伏歪が上記範囲に含まれるセルロース微細繊維は、樹脂中において、強固に相互作用するものと考えられる。1/γの上限は、一態様において、1000以下であってよい。以下に、測定条件及び測定方法を説明する。
[測定条件]
測定機器:レオメーター HAAKE MERS(Thermo Fisher Scientific社製)
測定治具:共軸二重円筒(カップ:CCB25 DIN、ローター:CC25 DIN Ti)
測定モード:Oscillation
制御方法:応力制御
制御範囲:0.01 ~ 100 Pa
温度:25℃
2. 1.で調製した水分散液を25℃で24時間以上静置する。
3. レオメーターに治具を取り付け、ピペット若しくはスポイトを用いて、セルロース微細繊維水分散液を17.0±1.0g仕込む。
4. 設定に基づいて測定を実施し、解析結果(LVE解析)より降伏歪の逆数(1/γ)を算出する。
本実施形態のセルロース微細繊維は、必要に応じて繊維表面層が変性されていても良い。変性の方法としては、エステル化、エーテル化、ウレタン化が挙げられる。
変性の方法は好ましくはエステル化であり、中でも飽和モノカルボン酸類を用いたエステル化が好ましい。エステル化剤としては、具体的には酢酸、プロピオン酸、ペンタン酸(吉草酸)、ヘキサン酸(カプロン酸)など比較的短鎖のものから、パルミチン酸、ステアリン酸など長鎖のものまで挙げられるが、変性後のセルロース微細繊維の耐熱性の観点から、酢酸、プロピオン酸など鎖長の短いものを用いることがより好ましい。
本実施形態のセルロース微細繊維は、ゼータ電位が-50mV以上、50mV以下であることが好ましい。ゼータ電位がこの範囲にあることで、反応性を低く制御できるため、熱による分解が生じにくく、樹脂などに配合する際に、着色、及び補強効果の低下が生じにくい。元来、セルロース微細繊維は-20mV~30mV程度の、微弱な負のゼータ電位を有するが、前述の表面処理を行う際にも、変性後のセルロース微細繊維のゼータ電位が上記範囲となるようにすることが好ましい。
一態様に係るセルロース微細繊維は、ハロゲン含有量が250質量ppm以下であるセルロース微細繊維(本開示で、低ハロゲンセルロース微細繊維ともいう。)であってよい。植物由来のセルロース微細繊維を樹脂と複合化する際、セルロース微細繊維の存在が、樹脂の分解、及び、混練装置、成型装置等の装置の内部の腐食という問題を招来する場合がある。低ハロゲンセルロース微細繊維は、ハロゲン含有量が特定以下であることによって、例えば植物由来であっても、セルロース微細繊維と樹脂との複合化時の樹脂の分解を抑制できる。低ハロゲンセルロース微細繊維を用いて得られる繊維強化樹脂は、長期保存時の安定性に優れ、マテリアルリサイクルのように溶融混練に伴う熱履歴を複数回経ても安定であることができる。また、低ハロゲンセルロース微細繊維によれば、セルロース微細繊維に起因する装置の腐食も抑制できる。
セルロース微細繊維を純水中で、25℃及び48時間にて浸漬処理する。具体的には、セルロース微細繊維を全容量200mLのガラス製ビーカー中に固形分2質量%で純水に浸漬し、3-1モーター(HEIDON製BL-600型、SUS製プロペラ翼、100rpm)で1時間攪拌後に静置する。次いで、テフロン(登録商標)製メンブレンフィルター(目開き1μm)を用いて減圧濾過し、目付10g/m2のシートを作製し、70℃の通風オーブン中で水分10質量%以下になるまで濾過乾燥を行って、処理後セルロース微細繊維を得る。ここで、水分量は以下の方法で測定される。セルロース試料2.00gをガラス製秤量ビンに導入し、60℃で15時間、その後、105℃で2時間乾燥し、デシケータ内で恒量した後、重量を測定し以下の式で求める。水分量(質量%)=(乾燥前の試料重量-乾燥後の試料重量)/(乾燥前の試料重量)x100
石英製の試料ボートに、上記の処理後セルロース微細繊維を50mg量りとる。試料ボートを電気炉(株式会社三菱化学アナリティック製)にセットし1000℃で燃焼する。燃焼により発生したガスは、冷却部を経て常温となり、フッ素樹脂製のチューブを通して吸収液(吸収液は、酒石酸イオン10mg/L、過酸化水素600mg/L、炭酸ナトリウム2.7mmol/L、炭酸水素ナトリウム0.3mmol/Lをイオン交換水に溶解したもの)にバブリングされる。この吸収液をフッ素樹脂製のチューブを通してイオンクロマト分析装置(THERMOFISHER製 INTEGRION CT型)を使用してハロゲンを定量する。なお定量は、種々のハロゲン含有量のサンプルで作成した検量線に基づいて行う。この際、前述の測定で得た水分量を処理後セルロース微細繊維から差し引く。最終的に、処理後セルロース微細繊維の乾燥質量(すなわち水を含まない状態)あたりに換算した値(質量ppm)を、本実施形態のセルロース微細繊維のハロゲン含有量とする。
セルロース繊維の前述のハロゲン含有量、及び後述の白色度を達成する観点から、解繊に供されるセルロース原料におけるハロゲン含有量(一態様において塩素含有量)は、好ましくは、300質量ppm以下、より好ましくは250質量ppm以下、更に好ましくは200質量ppm以下、特に好ましくは150質量ppm以下、格段に好ましくは100質量ppm以下である。セルロース原料のハロゲン含有量(一態様において塩素含有量)は少ない程望ましいが、セルロース微細繊維の製造効率の観点から、一態様において、10質量ppm以上、又は25質量ppm以上であってもよい。なお上記ハロゲン含有量は、セルロース微細繊維について前述したのと同様の方法で測定される、セルロース原料の乾燥質量あたりの量である。
セルロース微細繊維、特に低ハロゲンセルロース微細繊維は、白色度が50%以上であることが好ましい。ここでいう白色度は、分光白色度計・色差計(日本電色工業株式会社製 PF700型)を使用し、「紙・板紙及びパルプのISO白色度拡散青色光反射率の測定方法(JIS P8148、ISO 2470)」で測定される値のことをいう。セルロース原料又はセルロース微細繊維がシート状で得られる場合、これらをそのまま測定に供する。一方、湿潤状態の場合は、セルロース原料又はセルロース微細繊維を目付け50g/m2以上となるように、ポリテトラフルオロエチレン(PTFE)製メンブレンフィルターを備えた吸引濾過装置で抄紙し、80℃で平衡水分になるまで乾燥して、セルロースシートを作製し、これを用いて、上述の装置で白色度の測定を行う。白色度が高いほど、セルロース微細繊維は耐熱性に優れるため、樹脂と溶融混練で複合化して得られる樹脂組成物をメカニカルリサイクルした際の強度、弾性率、及び寸法安定性が向上するため好ましい。セルロース微細繊維の白色度は、より好ましくは60%以上であり、さらに好ましくは70%以上であり、特に好ましくは80%以上であり、格段に好ましくは90%以上であり、最も好ましくは95%以上である。この値が大きいほど本実施形態の効果が高まるため上限は限定されないが、実質的に得られる範囲としては99%以下が好ましい。
(セルロース原料の漂白方法)
一態様において、セルロース原料の漂白方法としては、塩素処理、アルカリ抽出処理、ハイポクロライト処理、二酸化塩素処理、酸素漂白処理、過酸化水素漂白処理、及びオゾン漂白処理からなる群から選ばれる1つ以上を用いることができる。
本実施形態におけるセルロース微細繊維は、粗すぎず細かすぎない適度な微細さを持ち、且つ、均質性が良いため、繊維強化樹脂用の強化フィラーとして好適に使用可能である。更に、シート状に成形して樹脂含侵することでプリプレグ材として用いること、コンクリート等の建築材料に用いること、等も可能である。
本発明の一態様は、本開示のセルロース微細繊維と樹脂とを含む繊維強化樹脂を提供する。一態様において、樹脂はセルロース微細繊維に含浸されている。繊維強化樹脂を得る方法としては、特に限定されないが、溶媒に溶解した樹脂とセルロース微細繊維を混合して溶媒を乾燥させる方法や、セルロース微細繊維を分散剤等と混合した後に乾燥させて、二軸押し出し機によって、溶融混練した樹脂に添加する方法、セルロース微細繊維を湿式抄紙し、シート化した後に樹脂を含侵させて複合化する方法、セルロース微細繊維と合成繊維とを混合し、例えば湿式抄紙によって不織布化したのち、当該合成繊維の融点以上で熱プレスを行う方法が挙げられる。一態様において、繊維強化樹脂の製造方法は、セルロース微細繊維を合成繊維(一態様において合成短繊維)と混合、湿式抄造することで不織布化して不織布を形成したのち、当該不織布を熱プレスにより成形する方法(以下、不織布化法と呼称)、セルロース微細繊維のスラリーを調製し、これをスプレードライヤー、減圧乾燥器などの公知の乾燥機に供して乾燥粉末とした後、二軸押出混練機によって樹脂を溶融混練する際に当該乾燥粉末を添加する方法、等であってよい。
本実施形態に用いる樹脂(すなわちマトリックス樹脂)は、熱硬化性樹脂、光硬化性樹脂、又は熱可塑性樹脂であってよい。その中でも、本実施形態のセルロース微細繊維は耐熱性に優れることから、熱可塑性樹脂が好ましい。本実施形態のセルロース微細繊維は、例えば、融点200℃以上、溶融混練温度250℃以上の樹脂とも好適に複合化できる。熱可塑性樹脂として、例えば、スチレン系樹脂、アクリル系樹脂、脂肪族又は芳香族のポリカーボネート系樹脂、脂肪族又は芳香族のポリエステル系樹脂(ポリエチレンテレフタレート、ポリ乳酸等)、鎖状ポリオレフィン系樹脂、環状オレフィン系樹脂、脂肪族又は芳香族のポリアミド系樹脂、ポリフェニレンエーテル系樹脂、ポリビニルアルコール系樹脂、ポリオキシアルキレン系樹脂、ポリフェニレンスルフィド系樹脂、熱可塑性ポリイミド系樹脂、ポリアセタール系樹脂、ポリスルホン系樹脂、非晶性フッ素系樹脂、エポキシ系樹脂等が挙げられる。これらの熱可塑性樹脂は、単独で又は2種以上を含有してもよい。
繊維強化樹脂中に含まれるセルロース微細繊維の含有率としては、強化繊維としての効果が良好である点で、好ましくは1質量%以上、より好ましくは5質量%以上、さらに好ましくは10質量%以上、さらに好ましくは20質量%以上である。セルロース微細繊維の含有量が多すぎると、繊維強化樹脂中の樹脂の連続層が分断されて繊維強化樹脂の性能が低下する傾向があること、及び、一態様においては繊維強化樹脂成形時の流動性が低く成形不良を起こし易い傾向があることから、上限としては、好ましくは60質量%以下、より好ましくは50質量%以下、さらに好ましくは40質量%以下である。
セルロース微細繊維と樹脂とを含む繊維強化樹脂を得る方法としては、例えば不織布化法を用いてよい。不織布は、一態様において本開示のセルロース微細繊維を含み、一態様において本開示のセルロース微細繊維と合成繊維とを含む。繊維強化樹脂における複合則によれば、繊維強化樹脂の強度は、樹脂中における繊維の配向性、及び繊維の連続性に大きく依存しており、繊維の配向及び連続性を制御することは、繊維強化樹脂の強度を制御する上で有利である。該不織布化法を用いることで、樹脂中においてセルロース微細繊維が水素結合によって連続層化し、該連続層が二次元平面方向に高度に配向した構造体となり強度に優れた材料が得られる。
不織布化法で用いる合成繊維は、一態様において合成短繊維である。合成短繊維とは、合成高分子の繊維を任意の繊維長に切断したものを指し、カット繊維、又は単に短繊維ということもある。合成短繊維は、一態様において、平均繊維長20mm以下、又は一態様において10mm以下の繊維であってよい。合成短繊維は、紡糸後カットした状態の繊維を叩解処理等によりフィブリル化させたフィブリル化繊維、或いはフラッシュ紡糸又はエレクトロスピニング法による紡糸等により得られる多分岐構造の繊維を紡糸した後に裁断したフィブリル化繊維であってもよい。合成繊維の材質の好適例は、樹脂について前述で例示したとおりである。
以下、不織布化法の具体的手順を例示する。不織布化法は、セルロース微細繊維と合成繊維とを、水を含む媒体中で撹拌、混合してスラリーを得るスラリー調製工程、当該スラリーから湿式抄造法により湿潤成型体を得る抄造工程、当該湿潤成型体を乾燥させて不織布を得る乾燥工程、及び当該不織布を、不織布中の合成繊維の融点以上の温度で熱プレスして繊維強化樹脂を得る熱プレス工程を含む。
本工程では、セルロース微細繊維と合成繊維とを、水を含む媒体中で攪拌して、束になった合成繊維を、単分散させるとともにセルロース微細繊維中に高度に分配する。攪拌装置としては、ホモミキサー、ブレンダーミキサーなど公知の攪拌装置が使用可能である。ここで、セルロース微細繊維及び合成繊維の固形分濃度の合計は、セルロース微細繊維と合成繊維とを高度に分散させることで最終的に得られる繊維強化樹脂の弾性率を高くする観点、及び、セルロース微細繊維の二次元方向での配向性を高くして強度及び破壊歪を大きくする観点から、好ましくは、3.0質量%以下、又は1.0質量%以下、又は0.8質量%以下であり、濾過時間を短縮して生産性を向上させる観点から、好ましくは、0.05質量%以上、又は0.1質量%以上、又は0.25質量%以上である。この時、合成繊維の分散性を向上させ、又は合成繊維とセルロース微細繊維との混合性を向上させる目的で、界面活性剤、粘剤などの分散剤を用いてもよい。
本工程では、スラリーを湿式抄造法により脱水して、湿潤成形体として湿潤不織布を得る。一態様においては、スラリーを多孔質基材上で吸引濾過することで脱水を行う。抄造法においては、スラリーを脱水し、セルロース微細繊維及び合成繊維が留まるような孔径を備える任意の濾材を使用できる。具体的な濾材としては、濾紙、濾布、金属メッシュなどが挙げられる。この時、吸引濾過に加え、湿潤成形体を、上部からロール等で接触加圧するプレス工程を併用することで、より効果の高い脱水効果を得られる。
本工程では、湿潤成形体を少なくとも乾燥させて不織布を得る。乾燥方法は特に限定されないが、ドラムドライヤー、ピンテンター等の方法で、湿潤成形体の幅を定長とした状態で、液体媒体を乾燥し得るタイプの定長乾燥型の乾燥機を使用して行うことが好ましい。このような乾燥機を用いることで、乾燥時に不織布の内部構造の変化が小さく、不織布内でのセルロース微細繊維の配向性を制御しやすい。なお、不織布の透気抵抗度は、スラリーを構成するセルロース微細繊維と合成繊維との組成比、全体の目付、原液の分散方法、各種添加剤の配合条件、セルロース微細繊維の平均繊維径等でコントロールすることができる。
本工程では、乾燥工程で得られた不織布を、加熱された型を用いてプレスすることによって、不織布に含まれる合成繊維を溶融、流動させ、空隙を埋め、セルロース微細繊維と樹脂との複合体である繊維強化樹脂を得る。この時、セルロース微細繊維は熱によって溶融しないため、不織布内部で二次元面方向に高度に配向した状態を維持することが可能である。加熱温度は合成繊維の融点以上であれば構わないが、融点付近では樹脂の粘度が高く、複合体内部に空隙が残ることがある。よって、加熱温度は合成繊維の融点より10℃以上高いことが好ましい。なお成形体の厚みを調整するために、不織布を複数枚積層して熱プレス工程に供しても良い。
一態様においては、不織布化法において前述したのと同様にしてセルロース微細繊維のスラリーを調製し、これをスプレードライヤー、減圧乾燥器などの公知の乾燥機に供して乾燥粉末とした後、二軸押出混練機によって樹脂を溶融混練する際に当該乾燥粉末を添加することによって繊維強化樹脂を製造してもよい。
本実施形態によって得られる、セルロース微細繊維と樹脂との複合体である繊維強化樹脂は、弾性率、強度、及び破壊歪のすべての力学物性に優れており、自動車部品、建築材料、家電などの広範な用途に好適に使用可能である。
≪項目群I≫
[1] 少なくとも表面が化学修飾されたセルロース微細繊維であって、
繊維形状分析計の測定において、繊維長100μm以上の繊維の長さ加重平均繊維長が110μm以上500μm以下であり、
繊維長が100μm以上の繊維のうち、長さ加重繊維長が411μm以上の繊維の数頻度が54%以下である、
セルロース微細繊維。
[2] 繊維形状自動分析計の測定において
(1)平均繊維径が42.5μm以下、
(2)ファイン繊維面積比が90%以下、
(3)繊維長100μm未満の繊維のうち、20μm以上56μm以下の繊維長を有する繊維の数頻度が30%以上97%以下、及び
(4)フィブリル化率が5%以下、
をすべて満たす、上記項目1に記載のセルロース微細繊維。
[3] 化学修飾がアセチル化であり、アセチル化度が0.5~1.3である、上記項目1又は2に記載のセルロース微細繊維。
[4] 構成糖分析におけるグルコース含有率が90質量%以上である、上記項目1~3のいずれかに記載のセルロース微細繊維
[5] セルロース微細繊維の5質量ppmDMSO分散液をキャスト及び乾燥して得た試料の表面の走査型電子顕微鏡(SEM)画像において、セルロース微細繊維の占める総面積に対する、占有面積が15μm2未満である極微小繊維の総占有面積の割合が10%以上80%以下である、上記項目1~4のいずれかに記載のセルロース微細繊維。
[6] セルロースI型の結晶構造を有する、上記項目1~5のいずれかに記載のセルロース微細繊維。
[7] 結晶化度が60%以上である、上記項目1~6のいずれかに記載のセルロース微細繊維。
[8] 上記項目1~7のいずれかに記載のセルロース微細繊維と、融点200℃以上の樹脂とを含む、繊維強化樹脂。
[9] 上記項目1~7のいずれかに記載のセルロース微細繊維を含む、不織布。
[10] 融点300℃以下の合成繊維を50質量%以上含む、上記項目9に記載の不織布。
[11] 上記項目9に記載の不織布と前記不織布に含浸されている樹脂とを含む、繊維強化樹脂。
[12] セルロース微細繊維と樹脂とを含む繊維強化樹脂の製造方法であって、
上記項目10に記載の不織布を熱プレスして繊維強化樹脂を得る工程を含み、
前記熱プレスを、前記合成繊維の融点以上で行う、繊維強化樹脂の製造方法。
[1] 繊維形状自動分析計の測定において、
(i)平均繊維長が130μm以上350μm以下、
(ii)平均繊維径が35μm以下、
(iii)微細繊維面積比が75%以下、
(iv)繊維長100μm未満の繊維のうち、20μm以上56μm以下の繊維長を有する繊維の数頻度が75%以下、
(v)繊維長100μm以上の繊維のうち、411μm以上の繊維長を有する繊維の数頻度が30%以下、及び
(vi)フィブリル化率が5.0%以下、
のすべてを満たす、セルロース微細繊維。
[2] 濃度0.75質量%の水分散スラリーにおいて、歪分散測定における降伏歪(γ)の逆数、1/γが200以上である、上記項目1に記載のセルロース微細繊維。
[3] ゼータ電位が-50mV以上50mV以下である、上記項目1又は2に記載のセルロース微細繊維。
[4] 上記項目1~3のいずれかに記載のセルロース微細繊維1.0質量%以上と、樹脂とを含む、繊維強化樹脂。
[5] 上記項目1~3のいずれかに記載のセルロース微細繊維を1.0質量%以上含む、不織布。
[6] 融点250℃以下の合成繊維を50質量%以上含む、上記項目5に記載の不織布。
[7] セルロース微細繊維と合成樹脂とを含む繊維強化樹脂の製造方法であって、
セルロース微細繊維と合成繊維とを含む不織布を熱プレスして繊維強化樹脂を得る工程を含み、
前記不織布が、上記項目5又は6に記載の不織布であり、
前記熱プレスを、前記合成繊維の融点以上で行う、繊維強化樹脂の製造方法。
[1] 植物由来であり、ハロゲン含有量(より具体的にはセルロースと結合したハロゲンの含有量)が250質量ppm以下である、セルロース微細繊維。
[2] 白色度が50%以上である、上記項目1に記載のセルロース微細繊維。
[3] 上記項目1又は2に記載のセルロース微細繊維の製造方法であって、
ハロゲン含有量(より具体的にはセルロースと結合したハロゲンの含有量)が300質量ppm以下であるセルロース原料を解繊する工程を含む、セルロース微細繊維の製造方法。
[4] 前記セルロース原料が化学修飾物である、上記項目3に記載のセルロース微細繊維の製造方法。
[5] 前記化学修飾物がアセチル化物である、上記項目4に記載のセルロース微細繊維の製造方法。
[6] 前記セルロース原料がコットン由来である、上記項目3~5のいずれかに記載のセルロース微細繊維の製造方法。
[7] 前記解繊がディスクリファイナーによる叩解処理である、上記項目3~6のいずれかに記載のセルロース微細繊維の製造方法。
[8] 上記項目1又は2に記載のセルロース微細繊維と、樹脂とを含む、樹脂組成物。
[9] 上記項目3~7のいずれかに記載の方法でセルロース微細繊維を得る工程と、
前記セルロース微細繊維と樹脂とを混合して樹脂組成物を得る工程と、
を含む、樹脂組成物の製造方法。
≪測定方法≫
[繊維形状自動分析計測定]
セルロース微細繊維の種々の特性を、繊維形状自動分析装置(TechPap社製 MorfiNeo)を用い、以下の手順で評価した。
1. セルロース微細繊維を純水に分散し、1Lの水分散体を用意した。ここで、セルロース微細繊維の固形分終濃度は0.003~0.005質量%とした。なお、希釈前のセルロース微細繊維が2質量%未満の水分散体(すなわち製造例6、7、11)については、スパチュラ等で簡易的に混ぜるだけとし、2質量%以上の水分散体、含水ケーク若しくは粉末状(すなわち製造例1~5、8~10、12、製造比較例1~7)については、高せん断ホモジナイザー(IKA製、商品名「ウルトラタラックスT18」)を用い処理条件:回転数25,000rpm×5分間で分散処理を行った。いずれの製造例についても、水以外の媒体に分散されていることから、上記高せん断ホモジナイザーを用い処理条件:回転数25,000rpm×5分間で、充分量の純水中に分散処理を行ったのち、吸引濾過等の手段で、媒体を除去、再度、上記高せん断ホモジナイザーを用い純水中に、処理条件:回転数25,000rpm×5分間で、固形分終濃度0.003~0.005質量%となるように分散処理を行うことで、媒体を水に置換した。
2. 1.で調製した水分散体をオートサンプラーに供し、測定を行った。
3. 測定結果をtxt形式(又はcsv形式)で出力した。
4. 測定結果より各形状パラメータを抽出、又は算出した。なお、各パラメータは測定結果のうち次の値を利用した。
通常繊維(繊維長100μm以上の繊維)における平均繊維長:Mean arithmetic length[μm]
通常繊維における繊維長411μm以上の繊維の数頻度:通常繊維の長さ加重繊維長分布(length-weighted Fiber lemgth,μm) より算出した。
平均繊維径:Mean fiber width[μm]
ファイン繊維面積比:Fine content,% in Area
ファイン繊維(繊維長100μm未満の繊維)における繊維長20μm以上56μm以下の繊維の数頻度:ファイン繊維の繊維長分布(Fine length、μm:FL)より算出した。
フィブリル化率:MacroFibrillation index[%]
比表面積・細孔分布測定装置(Nova-4200e,カンタクローム・インスツルメンツ社製)にて、セルロース微細繊維約0.2gを真空下で120℃、5時間乾燥を行った後、液体窒素の沸点における窒素ガスの吸着量を相対蒸気圧(P/P0)が0.05以上0.2以下の範囲にて5点測定した後(多点法)、同装置プログラムによりBET比表面積(m2/g)を算出することで測定した。
セルロースの密度は1.5(g/cm3)であるため、セルロース1g当たりの体積は、6.7×10-7(m3/g)である。
セルロース微細繊維の換算平均繊維径をr(m)とすると、セルロース微細繊維の平均外周長=πr、セルロース微細繊維の平均断面積=0.25πr2、であるので、セルロース微細繊維1g当たりでは、合計繊維長=6.7×10-7(m3)/平均断面積(=0.25πr2)
総表面積=比表面積(m2)=6.7×10-7(m3)/平均断面積(=0.25πr2)×平均外周長(=πr)=6.7×10-7(m3)/0.25r
である。従って、例えば比表面積40m2のCNFの平均繊維径rは67nmと算出される。
占有面積比率は、フィールドエミッション型走査型電子顕微鏡((株)日立製作所製、FE-SEM Regulus8220/5060FQ)を用い、以下の手順で測定した。
2. 平滑な基板(シリコンウエハー)にオスミウムプラズマコーティングを施し、ホットプレート上で130℃に加熱した。
3. 加熱した平滑な基板の中央にDMSO分散液を7μL滴下し、加熱下で静置乾燥させ、セルロース微細繊維を基板上に固定した。
4. 得られたセルロース微細繊維を固定した基板を走査型電子顕微鏡(SEM)にて、加速電圧1.5kV、観察倍率400倍、100μm当たり400ピクセル以上の解像度で基板上の任意の異なる場所で4枚画像を撮影した。
5. SEM画像のスケールバーのピクセル数から閾値である15μm2に相当するピクセル数を算出した。
6. 取得したSEM画像から、画像処理ソフトウェアImageJを用いて、MaxEntropy法で二値化像を作成した。
7. 二値化像をImageJのAnalyze Particleを用いて粒子解析し、セルロース微細繊維の単繊維の面積(ピクセル)を算出した。
8. 撮影した4画像の粒子解析結果を合算し、2ピクセル以下をノイズとして削除し、閾値として面積15μm2未満を極微小繊維とし、セルロース微細繊維の総面積に占める15μm2未満の極微小繊維の面積の比率を算出した。
セルロース微細繊維の構成糖分析によるグルコース含有率は、米エネルギー省の国立再生可能エネルギー研究所の分析手順(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.)を参考に、以下の手順で測定した。
セルロース微細繊維のアセチル置換度(DS)は赤外分光計(日本分光製、FT/IR-6200)及び核磁気共鳴装置(NMR)(Bruker社製、AVANCE III 500MHz)を用い、以下の手順で評価した。
アセチル置換度(DS)は、セルロース微細繊維の反射型赤外吸収スペクトルから、アセチル基由来のピークとセルロース骨格由来のピークとのピーク強度比に基づいて算出した。アセチル基に基づくC=Oの吸収バンドのピークは1730cm-1に出現し、セルロース骨格鎖に基づくC-Oの吸収バンドのピークは1030cm-1に出現する。セルロース微細繊維のDSは、後述するセルロース微細繊維の固体NMR測定から得られるDSと、セルロース骨格鎖C-Oの吸収バンドのピーク強度に対するアセチル基に基づくC=Oの吸収バンドのピーク強度の比率で定義される修飾化率(IRインデックス1030)との相関グラフを作製し、相関グラフから算出された検量線置換度DS = 4.13 × IRインデックス(1030)
を使用することで求めた。
DS=(Inf)×6/(Inp)
修飾基はアセチル基であることから、-CH3に帰属される23ppmのシグナルを用いた。
装置 :Bruker Biospin Avance500WB
周波数 :125.77MHz
測定方法 :DD/MAS法
待ち時間 :75sec
NMR試料管 :4mmφ
積算回数 :640回(約14Hr)
MAS :14,500Hz
化学シフト基準:グリシン(外部基準:176.03ppm)
セルロース微細繊維の結晶化度は、X線回折装置(リガク社製、MiniFlex II)を用い、以下の方法で評価した。
サンプルを広角X線回折により測定した際の回折パターン(2θ/deg.が10~30)からSegal法により、以下の式で求めた。
結晶化度(%)=[I(200)-I(amorphous)]/I(200)×100
I(200):セルロースI型結晶における200面(2θ=22.5°)による回折ピーク強度
I(amorphous):セルロースI型結晶におけるアモルファスによるハローピーク強度であって、200面の回折角度より4.5°低角度側(2θ=18.0°)のピーク強度
分光白色度計・色差計(日本電色工業株式会社製 PF700型)を使用し、「紙・板紙及びパルプのISO白色度拡散青色光反射率の測定方法(JIS P8148・ISO 2470)」にて測定した。セルロース原料又はセルロース微細繊維のスラリーを、目付け50g/m2以上となるように、ポリテトラフルオロエチレン(PTFE)製メンブレンフィルターを備えた吸引濾過装置で抄紙し、80℃で平衡水分になるまで乾燥して、セルロースシートを作製し、上記測定に供した。
(浸漬・濾過処理)
セルロース原料又はセルロース微細繊維を純水中で、25℃及び48時間にて浸漬処理した。具体的には、セルロース原料又はセルロース微細繊維を全容量200mLのガラス製ビーカー中に固形分2質量%で純水に浸漬し、3-1モーター(HEIDON製BL-600型、SUS製プロペラ翼、100rpm)で1時間攪拌後に静置した。次いで、テフロン(登録商標)製メンブレンフィルター(目開き1μm)を用いて減圧濾過し、目付10g/m2のシートを作製し、70℃の通風オーブン中で水分10質量%以下になるまで濾過乾燥を行って、処理後セルロース原料又は処理後セルロース微細繊維を得た。
石英製の試料ボートに、上記の処理後セルロース原料又は処理後セルロース微細繊維を50mg量りとった。試料ボートを電気炉(株式会社三菱化学アナリティック製)にセットし1000℃で燃焼した。燃焼により発生したガスは、冷却部を経て常温となり、フッ素樹脂製のチューブを通して吸収液(吸収液は、酒石酸イオン10mg/L、過酸化水素600mg/L、炭酸ナトリウム2.7mmol/L、炭酸水素ナトリウム0.3mmol/Lをイオン交換水に溶解したもの)にバブリングされた。この吸収液をフッ素樹脂製のチューブを通してイオンクロマト分析装置(THERMOFISHER製 INTEGRION CT型)を使用してハロゲンを定量した。なお定量は、種々のハロゲン含有量のサンプルで作成した検量線に基づいて行った。この際、乾燥減量法(セルロース試料2.00gをガラス製秤量ビンに導入し、60℃で15時間、その後、105℃で2時間乾燥し、デシケータ内で恒量した後、重量を測定し以下の式で求める。水分量(質量%)=(乾燥前の試料重量-乾燥後の試料重量)/(乾燥前の試料重量)x100)によって、処理後セルロース原料中又は処理後セルロース微細繊維中の水分量を差し引いた。最終的に、処理後セルロース原料又は処理後セルロース微細繊維の乾燥質量(すなわち水を含まない状態)あたりに換算した値(質量ppm)を、セルロース繊維内に残存するハロゲンの含有量とした。
セルロース微細繊維と樹脂とを混練して得た繊維強化樹脂サンプルの外観について、明らかに焦げているものを不良、やや焦げているものを可、変色がみられないものを良とした。
混練物から、最大型締付圧力75トンの射出成形機を用いて、ISO-37に準拠した多目的試験片(繊維強化樹脂として)を成形し、JIS K6920-2に準拠した条件で引張試験を実施し、引張強度、引張弾性率、及び破断歪を測定した。尚、ポリアミド樹脂は吸湿による変化が起きるため、成形直後にアルミ防湿袋に保管し、吸湿を抑制した。
曲げ試験は、射出成形法により作製した繊維強化樹脂については幅:10mm、長さ:80mm、厚み:4mmの短冊を作製し、不織布化法により作製した板状の繊維強化樹脂については、幅:2.5mm、長さ:50mmの短冊を切り出し、JIS K7171:2008に準拠した条件にて、曲げ強さ、曲げ弾性率、及び曲げ歪を測定した。尚、ポリアミド樹脂は吸湿による変化が起きるため、成形直後にアルミ防湿袋に保管し、吸湿を抑制した。
引張試験用と同様の多目的試験片を、チャック付きポリエチレンの袋に入れ、100℃で1か月保存後に、常温に戻し1日放置した後、目視観察した。目視で変色が認めらなかったものを良、目視で変色が認められたものを不良とした。
曲げ試験用と同様の短冊を、カッターでφ5mm以下にカットし、超遠心粉砕機(Retsch社製ZM200型、スクリーン目開きφ2mm、回転数10000rpm)で2パス処理した。各実施例及び比較例において、各例記載の方法による溶融混練と射出成型を行い、これを5回繰り返した後に、曲げ強度を測定した。保存前との比較において、曲げ強度の保持率90%以上を良、90%未満を不良とした。
[パルプ]
(リンターパルプA)
日本紙パルプ商事(株)より入手した天然セルロースであるリンターパルプA(以下、パルプA)は、前述の繊維形状自動分析計で測定された長さ加重平均繊維長が1660μmであった。
日本紙パルプ商事(株)より入手した天然セルロースであるリンターパルプB(以下、パルプB)は、前述の繊維形状自動分析計で測定された長さ加重平均繊維長が1006μmであった。
日本紙パルプ商事(株)より入手した天然セルロースである木材パルプ(NBLP)C(以下、パルプC)は、前述の維形状自動分析計で測定された長さ加重平均繊維長が1315μmであった。
上記パルプAを、パルプ濃度が5質量%になるようにジメチルスルホキシド中に浸漬し、触媒として炭酸カリウムを0.1質量%添加し、パルプを撹拌羽根で十分に分散、膨潤させた。60℃に加温し、酢酸ビニルを添加してアセチル化を行い、アセチル化リンターパルプD(以下、アセチル化パルプD)を得た。
上記パルプBを、パルプ濃度が5質量%になるようにジメチルスルホキシド中に浸漬し、触媒として炭酸カリウムを0.1質量%添加し、パルプを撹拌羽根で十分に分散、膨潤させた。60℃に加温し、酢酸ビニルを添加してアセチル化を行い、アセチル化リンターパルプE(以下、アセチル化パルプE)を得た。
(製造例1)
パルプAを固形分1.5質量%になるように水に浸漬し、ラボパルパー(相川鉄工社製)を用いて分散させて得たスラリーを、シングルディスクリファイナー(相川鉄工社製、SDR14型ラボリファイナー 加圧型DISK式)と、当該ディスクリファイナーを介して配線で接続されたタンクA及びBとを備える解繊装置に導入してパルプを解繊した。まず、スラリーを投入したタンクAからディスクリファイナーを介してタンクBへ送液、貯蔵し、該タンクAのスラリーの処理を終えた段階で、連続的に該タンクBから該ディスクリファイナーを介して該タンクAへ送液、貯蔵する方法により、該ディスクリファイナーを通過した回数(パス回数)を制御して解繊を行った。尚、該ディスクリファイナーの刃間調整機構として、ボールねじ式ジャッキと減速機を設けた。目的の刃間距離に到達させた後の叩解処理中の刃間距離のぶれ幅は変位センサーによる測定で0.005mm以下であった。ディスクリファイナーの刃として、刃幅4.0mm、刃溝比0.89の刃(ディスク刃A)を使用し、刃間0.25mm、30パスさせた後、刃幅0.8mm、刃溝比0.53の刃(ディスク刃B)を用いて刃間距離0.25mmで30パスさせた。
製造例1と同様に、パルプAを固形分1.5質量%になるように水に浸漬し、ラボパルパーで分散させた後、ディスクリファイナーの刃幅2.5mm、刃溝比0.36の刃を使用し、刃間0.20mmで50パスさせたのち、刃幅0.6mm、刃溝比0.60の刃を使用し、刃間0.10mmで100パスさせた。尚、高圧ホモジナイザー処理は行わなかった。
製造例1と同様に、パルプBを固形分1.5質量%になるように水に浸漬し、ラボパルパーで分散させた後、ディスクリファイナーの刃幅2.5mm、刃溝比0.36の刃を使用し、刃間0.20mmで50パスさせたのち、刃幅0.8mm、刃溝比0.53の刃を使用し、刃間0.20mmで50パスさせた。
製造例1と同様に、パルプAを固形分3.0質量%になるように水に浸漬し、ラボパルパーで分散させた後、ディスクリファイナーの刃幅2.5mm、刃溝比0.36の刃を使用し、刃間0.20mmで30パスさせたのち、刃幅0.6mm、刃溝比0.60の刃を使用し、刃間0.20mmで30パスさせた。
製造例1と同様に、パルプAを固形分1.5質量%になるように水に浸漬し、ラボパルパーで分散させた後、ディスクリファイナーの刃幅2.5mm、刃溝比0.36の刃を使用し、刃間0.15mmで100パスさせたのち、刃幅0.8mm、刃溝比0.53の刃を使用し、刃間0.15mmで50パスさせた。
製造例1と同様に、アセチル化パルプDを固形分1.5質量%になるように水に浸漬させ、ラボパルパーで分散させた後、ディスクリファイナーの刃幅2.5mm、刃溝比0.36の刃を使用し、刃間0.05mmで75パスさせたのち、刃幅0.8mm、刃溝比0.53の刃を使用し、刃間0.05mmで40パスさせた。
製造例1と同様に、アセチル化パルプEを固形分1.5質量%になるように水に浸漬し、ラボパルパーで分散させた後、ディスクリファイナーの刃幅0.8mm、刃溝比0.53の刃を使用し、刃間0.15mmで50パスさせた。ディスクリファイナー処理は1段のみ行い、得られたスラリーを高圧ホモジナイザーで10パス処理を行った。
製造例1と同様に、パルプAを固形分1.5質量%になるように水に浸漬し、ラボパルパーで分散させた後、ディスクリファイナーの刃幅2.5mm、刃溝比0.36の刃を使用し、刃間0.15mmで100パスさせたのち、刃幅0.8mm、刃溝比0.53の刃を使用し、刃間0.15mmで50パスさせた。
製造例1と同様に、パルプAを固形分1.5質量%になるように水に浸漬し、ラボパルパーで分散させた後、ディスクリファイナーの刃幅2.5mm、刃溝比0.36の刃を使用し、刃間0.15mmで100パスさせたのち、刃幅0.8mm、刃溝比0.53の刃を使用し、刃間0.15mmで50パスさせた。
製造例1と同様に、パルプAを固形分1.5質量%になるように水に浸漬させ、ラボパルパーで分散させた後、ディスクリファイナーの刃幅2.5mm、刃溝比0.36の刃を使用し、刃間0.05mmで10パスさせたのち、刃幅0.8mm、刃溝比0.53の刃を使用し、刃間0.05mmで10パスさせた。
製造例1と同様に、アセチル化パルプEを固形分1.5質量%になるように水に浸漬し、ラボパルパーで分散させた後、ディスクリファイナーの刃幅0.8mm、刃溝比0.53の刃を使用し、刃間0.10mmで40パスさせた。ディスクリファイナー処理は1段のみ行い、得られたスラリーを高圧ホモジナイザーで10パス処理した。
製造例1と同様に、パルプBを固形分1.5質量%になるように水に浸漬し、ラボパルパーで分散させた後、ディスクリファイナーの刃幅2.5mm、刃溝比0.36の刃を使用し、刃間0.15mmで70パスさせたのち、刃幅0.6mm、刃溝比0.60の刃を使用し、刃間0.15mmで40パスさせた。
製造例1に記載のディスクリファイナーと高圧ホモジナイザーを用いて、パルプAを固形分1.5質量%になるように水に浸漬し、ラボパルパーで分散させたのち、ディスクリファイナーの刃幅2.5mm、刃溝比0.36の刃を使用し、刃間0.30mmで20パスさせたのち、刃幅0.8mm、刃溝比0.53の刃を使用し、刃間0.35mmで50パスさせた。
製造例1と同様に、パルプBを固形分1.5質量%になるように水に浸漬し、ラボパルパーで分散させたのち、ディスクリファイナーの刃幅2.5mm、刃溝比0.36の刃を使用し、刃間0.50mmで120パスさせたのち、刃幅0.6mm、刃溝比0.60の刃を使用し、刃間0.03mmで100パスさせた。尚、高圧ホモジナイザー処理は行わなかった。
製造例1と同様に、パルプCを固形分1.5質量%になるように水に浸漬し、ラボパルパーで分散させたのち、ディスクリファイナーの刃幅2.5mm、刃溝比0.36の刃を使用し、刃間0.35mmで40パスさせた。ディスクリファイナー処理は1段のみ行い、得られたスラリーを高圧ホモジナイザーで2パス処理した。
製造例1と同様に、パルプAを固形分1.5質量%になるように水に浸漬し、ラボパルパーで分散させたのち、ディスクリファイナーの刃幅4.0mm、刃溝比0.89の刃を使用し、刃間0.40mmで5パスさせた。ディスクリファイナー処理は1段のみ行い、高圧ホモジナイザー処理を行わなかった。
製造例1と同様に、パルプCを固形分1.5質量%になるように水に浸漬し、ラボパルパーで分散させたのち、ディスクリファイナーの刃幅2.5mm、刃溝比0.36の刃を使用し、刃間0.05mmで50パスさせたのち、刃幅0.8mm、刃溝比0.53の刃を使用し、刃間0.03mmで50パスさせた。
製造例1と同様に、パルプAを固形分1.5質量%になるように水に浸漬し、ラボパルパーで分散させたのち、ディスクリファイナーの刃幅2.5mm、刃溝比0.36の刃を使用し、刃間0.03mmで120パスさせたのち、刃幅0.8mm、刃溝比0.53の刃を使用し、刃間0.03mmで60パスさせた。
製造比較例7では、ランナー部のトラスト方向へ引っ張った際の移動量が0.3mmのシングルディスクリファイナーを用いた。
(射出成形による複合化:実施例I-1~I-12、比較例I-1~I-7)
得られた各化学修飾セルロース微細繊維を用いて、以下の手順にて射出成形による複合体である繊維強化樹脂を作製した。
1. 製造例1~12及び製造比較例1~7で作製した化学修飾セルロース微細繊維の湿潤ケーキをそれぞれヘキサフルオロイソプロパノール(以下、HFIPと呼ぶ)に固形分濃度1体積%になるようにホモジナイザー(IKA社製、ウルトラタラックスT18)を用いて、回転数12,000rpmで3分間、分散処理を行った。
2. ポリアミド6(宇部興産社製、1013B)をHFIPに固形分1質量%で溶解させた溶液を調製した。
3. 1及び2を、化学修飾セルロース微細繊維とポリアミド6の固形分質量比で1:9になるように容器に入れ、自転・交点ミキサー(シンキー社製、あわとり練太郎 ARE-310)で2,000rpmで5分間混合した。
4. 得られた3の混合液を離形フィルム(三井化学東セロ社製、X88B)上にフィルム上にキャストし、80℃のオーブンで1時間乾燥した。
5. 4を卓上粉砕機(ラボネクスト社製、ミニスピードミル MS-05)で粉砕した。
6. 5の粉末を真空乾燥機中で24時間以上乾燥させた。
7. 6を小型混練機(DSM社製、Xplore MC 15HT)にて、温度:250℃、回転数:200rpmで2分間混練した。
8. 混練終了後、射出成形機(Xplore IM12)に樹脂を流し込み、曲げ試験用の幅:10mm、長さ:80mm、厚み:4mmの短冊状の試験片と引張試験用のISO-37に準拠した多目的試験片(繊維強化樹脂として)を作製した。
得られた試験片の曲げ試験及び、引張試験による評価結果を表3に示す。
ポリプロピレン製の短繊維(カット長:2.0mm、繊度:0.2T)と上記で作製した化学修飾セルロース微細繊維を固形分質量比で80:20となるように、純水中に加え、固形分濃度0.5質量%のスラリーを得た。当該スラリーを家庭用ミキサーで4分間撹拌し、抄紙スラリーを調製した。濾布(敷島カンバス社製 TT35)をセットしたバッチ式抄紙機(熊谷力工業社製 自動角型シートマシン 25cm×25cm、80メッシュ)に、上記調製した抄紙スラリーを目付が300g/m2になるように投入し、その後、大気圧に対する減圧度を50kPaとして抄紙(脱水)した。
ポリアミド66製の短繊維(カット長:2.0mm、繊度:0.6T)と上記で作製した化学修飾セルロース微細繊維を固形分質量比で80:20となるように、純水中に加え、固形分濃度0.5質量%のスラリーを得た。当該スラリーを家庭用ミキサーで4分間撹拌し、抄紙スラリーを調製した。濾布(敷島カンバス社製 TT35)をセットしたバッチ式抄紙機(熊谷力工業社製 自動角型シートマシン 25cm×25cm、80メッシュ)に、上記調製した抄紙スラリーを目付が300g/m2になるように投入し、その後、大気圧に対する減圧度を50kPaとして抄紙(脱水)した。
≪測定方法≫
[繊維形状自動分析計測定]
セルロース微細繊維の種々の特性を、繊維形状自動分析計(Technidyne社製 Morfi neo)を用いて、以下の手順にて測定した。
1. セルロース微細繊維を純水に分散し、1Lの水分散体を準備した。なお固形分終濃度は約0.004質量%となるように調整した。いずれのセルロース微細繊維も固形分濃度2質量%以下の水分散体であったため、充填率75体積%以下とした密閉容器中で振り混ぜることで分散処理を行った。
2. 1.で調整した水分散体をオートサンプラーに供し、測定を行った。
3. 測定結果をtxt形式(又はcsv形式)で出力した。
4. 測定結果より、例Iと同様の形状パラメータを抽出、又は算出した。
例Iと同様に測定した。
以下の手順にて、セルロース微細繊維水分散体のレオロジー特性を測定し、降伏歪の逆数(1/γ)を算出した。なお、使用した測定機器及び測定条件は以下のように設定した。
(測定条件)
測定機器:レオメーター HAAKE MERS(Thermo Fisher Scientific社製)
測定治具:共軸二重円筒(カップ:CCB25 DIN、ローター:CC25 DIN Ti)
測定モード:Oscillation
制御方法:応力制御
制御範囲:0.01 ~ 100Pa
温度:25℃
1. セルロース微細繊維を純水に分散した。ここで、セルロース微細繊維の固形分終濃度は0.75質量%とした。いずれのセルロース微細繊維も固形分濃度2質量%以下の水分散体であったため、充填率75体積%以下とした密閉容器中で振り混ぜることで分散処理を行った。
2. 1.で調整した水分散液を25℃で24時間以上静置した。
3. レオメーターに治具を取り付け、スポイトを用いて、セルロース微細繊維水分散液を17.0 ± 1.0g仕込んだ。
4. 測定を実施し、LVE解析によって、降伏歪(γ)を算出し、その逆数(1/γ)を算出した。
例Iと同様に測定した。
例Iと同様に測定した。
後述の方法にて、ISO-37に準拠した多目的試験片を作製し、JIS K6920-2に準拠した条件にて、引張試験を実施し、引張強度、引張弾性率、破壊歪を測定した。
後述の方法にて、ISO-37に準拠した多目的試験片を作製し、以下の条件にてDMA測定を実施し、150℃における貯蔵弾性率を測定した。
装置:Gabo社エプレクサー500N
測定モード:引張
測定温度範囲:-130~200℃
昇温速度:3℃/min
静的負荷歪 : 0.5%
動的負荷歪 : 0.3%
振動周波数 : 10Hz
接触荷重:1N
不織布化法によって得られた板状の複合体から、幅:25mm、長さ:50mmの短冊を切り出しJIS K7171に準拠した条件にて、曲げ強さ、曲げ弾性率、及び曲げ破壊歪を測定した。
例Iと同様に測定した。
(セルロース微細繊維A)
日本紙パルプ商事(株)より入手した天然セルロースであるリンターパルプを用い、リンターパルプが1.5質量%となるように水に浸液させ、ラボパルパー(相川鉄工製)を用いて簡易的に分散させた後、タンクに送液した。該タンクと接続された、刃幅:2.5mm、溝幅:7.0mm、刃溝比:0.36のディスクを備えたシングルディスクリファイナー(前段)によって、スラリーを循環させながら微細化を施した。この時、刃間距離1.0mmから運転を開始し、徐々に刃間距離を詰めながら、最終的な刃間距離を0.05mmとした。刃間距離が0.05mmに達してから、さらに流量を確認しながら運転を継続し、スラリー全量が10回ディスク部を通過した段階で、運転を終了した。続いて、刃幅:0.6mm、溝幅:1.0mm、刃溝比:0.6のディスクを備えたシングルディスクリファイナー(後段)によって、スラリーを循環させながら微細化を施した。この時、刃間距離1.0mmから運転を開始し、徐々に刃間距離を詰めながら、最終的な刃間距離を0.05mmとした。刃間距離が0.05mmに達してから、さらに流量を確認しながら運転を継続し、スラリー全量が10回ディスク部を通過した段階で、運転を終了した。得られたセルロース微細繊維を、セルロース微細繊維A(MFC-A)とした。各種繊維形状パラメータ及びレオロジー特性の分析結果を表6に示す。
シングルディスクリファイナー(後段)による処理回数を30回とした以外は、セルロース微細繊維Aと同じ方法で、セルロース微細繊維B(MFC-B)を得た。各種繊維形状パラメータ及びレオロジー特性の分析結果を表6に示す。
日本紙パルプ商事(株)より入手した天然セルロースであるリンターパルプを用い、リンターパルプが1.5質量%となるように水に浸液させ、ラボパルパー(相川鉄工製)を用いて簡易的に分散させた後、タンクに送液した。該タンクと接続された、刃幅:2.5mm、溝幅:7.0mm、刃溝比:0.36のディスクを備えたシングルディスクリファイナー(前段)によって、スラリーを循環させながら微細化を施した。この時、刃間距離1.0mmから運転を開始し、徐々に刃間距離を詰めながら、最終的な刃間距離を0.3mmとした。刃間距離が0.3mmに達してから、さらに流量を確認しながら運転を継続し、スラリー全量が90回ディスク部を通過した段階で、運転を終了した。続いて、刃幅:0.8mm、溝幅:1.5mm、刃溝比:0.53のディスクを備えたシングルディスクリファイナー(後段)によって、スラリーを循環させながら微細化を施した。この時、刃間距離1.0mmから運転を開始し、徐々に刃間距離を詰めながら、最終的な刃間距離を0.15mmとした。刃間距離が0.15mmに達してから、さらに流量を確認しながら運転を継続し、スラリー全量が40回ディスク部を通過した段階で、運転を終了した。得られたセルロース微細繊維を、セルロース微細繊維C(MFC-C)とした。各種繊維形状パラメータ及びレオロジー特性の分析結果を表6に示す。
セルロース微細繊維Cを、高圧ホモジナイザー(ニロ・ソアビ社(伊)製NS015H)を用いて操作圧力100MPaにて10回微細化処理し、得られたセルロース微細繊維をセルロース微細繊維D(MFC-D)とした。各種繊維形状パラメータ及びレオロジー特性の分析結果を表6に示す。
日本紙パルプ商事(株)より入手した天然セルロースであるリンターパルプを用い、リンターパルプが1.5質量%となるように水に浸液させ、ラボパルパー(相川鉄工製)を用いて簡易的に分散させた後、タンクに送液した。該タンクと接続された、刃幅:2.5mm、溝幅:7.0mm、刃溝比:0.36のディスクを備えたシングルディスクリファイナー(前段)によって、スラリーを循環させながら微細化を施した。この時、刃間距離1.0mmから運転を開始し、徐々に刃間距離を詰めながら、最終的な刃間距離を0.05mmとした。刃間距離が0.05mmに達してから、さらに流量を確認しながら運転を継続し、スラリー全量が90回ディスク部を通過した段階で、運転を終了した。続いて、刃幅:0.8mm、溝幅:1.5mm、刃溝比:0.53のディスクを備えたシングルディスクリファイナー(後段)によって、スラリーを循環させながら微細化を施した。この時、刃間距離1.0mmから運転を開始し、徐々に刃間距離を詰めながら、最終的な刃間距離を0.05mmとした。刃間距離が0.05mmに達してから、さらに流量を確認しながら運転を継続し、スラリー全量が90回ディスク部を通過した段階で、運転を終了した。得られたセルロース微細繊維を、セルロース微細繊維E(MFC-E)とした。各種繊維形状パラメータ及びレオロジー特性の分析結果を表6に示す。
日本紙パルプ商事(株)より入手した天然セルロースであるリンターパルプを用い、リンターパルプが1.5質量%となるように水に浸液させ、ラボパルパー(相川鉄工製)を用いて簡易的に分散させた後、タンクに送液した。該タンクと接続された、刃幅:2.5mm、溝幅:7.0mm、刃溝比:0.36のディスクを備えたシングルディスクリファイナー(1台のみ)によって、スラリーを循環させながら微細化を施した。この時、刃間距離1.0mmから運転を開始し、徐々に刃間距離を詰めながら、最終的な刃間距離を0.05mmとした。刃間距離が0.05mmに達してから、さらに流量を確認しながら運転を継続し、スラリー全量が150回ディスク部を通過した段階で、運転を終了した。得られたセルロース微細繊維を、ミクロフィブリル化セルローF(MFC-F)とした。各種繊維形状パラメータ及びレオロジー特性の分析結果を表6に示す。
日本紙パルプ商事(株)より入手した天然セルロースであるリンターパルプを用い、リンターパルプが1.5質量%となるように水に浸液させ、ラボパルパー(相川鉄工製)を用いて簡易的に分散させた後、タンクに送液した。該タンクと接続された、刃幅:2.5mm、溝幅:7.0mm、刃溝比:0.36のディスクを備えたシングルディスクリファイナー(前段)によって、スラリーを循環させながら微細化を施した。この時、刃間距離1.0mmから運転を開始し、徐々に刃間距離を詰めながら、最終的な刃間距離を0.05mmとした。刃間距離が0.05mmに達してから、さらに流量を確認しながら運転を継続し、スラリー全量が10回ディスク部を通過した段階で、運転を終了した。続いて、刃幅:0.6mm、溝幅:1.0mm、刃溝比:0.6のディスクを備えたシングルディスクリファイナー(後段)によって、スラリーを循環させながら微細化を施した。この時、刃間距離1.0mmから運転を開始し、徐々に刃間距離を詰めながら、最終的な刃間距離を0.05mmとした。刃間距離が0.05mmに達した直後に運転を終了(ディスク部通過回数は、便宜的に0回と表現する)し、得られたセルロース微細繊維を、セルロース微細繊維G(MFC-G)とした。各種繊維形状パラメータ及びレオロジー特性の分析結果を表6に示す。
日本紙パルプ商事(株)より入手した天然セルロースであるリンターパルプを用い、リンターパルプが1.5質量%となるように水に浸液させ、ラボパルパー(相川鉄工製)を用いて簡易的に分散させた後、タンクに送液した。該タンクと接続された、刃幅:0.8mm、溝幅:1.5mm、刃溝比:0.53のディスクを備えたシングルディスクリファイナー(1台のみ)によって、スラリーを循環させながら微細化を施した。この時、刃間距離1.0mmから運転を開始し、徐々に刃間距離を詰めながら、最終的な刃間距離を0.05mmとした。刃間距離が0.05mmに達してから、さらに流量を確認しながら運転を継続し、スラリー全量が90回ディスク部を通過した段階で、運転を終了した。得られたセルロース微細繊維を、セルロース微細繊維H(MFC-H)とした。各種繊維形状パラメータ及びレオロジー特性の分析結果を表6に示す。
日本紙パルプ商事(株)より入手した天然セルロースであるリンターパルプを用い、リンターパルプが1.5質量%となるように水に浸液させ、ラボパルパー(相川鉄工製)を用いて簡易的に分散させた後、タンクに送液した。該タンクと接続された、刃幅:4.0mm、溝幅:4.5mm、刃溝比:0.89のディスクを備えたシングルディスクリファイナー(前段)によって、スラリーを循環させながら微細化を施した。この時、刃間距離1.0mmから運転を開始し、徐々に刃間距離を詰めながら、最終的な刃間距離を0.05mmとした。刃間距離が0.05mmに達してから、さらに流量を確認しながら運転を継続し、スラリー全量が30回ディスク部を通過した段階で、運転を終了した。続いて、刃幅:0.8mm、溝幅:1.5mm、刃溝比:0.53のディスクを備えたシングルディスクリファイナー(後段)によって、スラリーを循環させながら微細化を施した。この時、刃間距離1.0mmから運転を開始し、徐々に刃間距離を詰めながら、最終的な刃間距離を0.05mmとした。刃間距離が0.05mmに達してから、さらに流量を確認しながら運転を継続し、スラリー全量が30回ディスク部を通過した段階で、運転を終了した。得られたセルロース微細繊維を、セルロース微細繊維I(MFC-I)とした。各種繊維形状パラメータ及びレオロジー特性の分析結果を表6に示す。
シングルディスクリファイナー(後段)による処理回数を180回とした以外は、セルロース微細繊維A(MFC-A)と同じ方法で、セルロース微細繊維J(MFC-J)を得た。各種繊維形状パラメータ及びレオロジー特性の分析結果を表6に示す。
日本紙パルプ商事(株)より入手した天然セルロースであるリンターパルプを用い、リンターパルプが1.5質量%となるように水に浸液させ、ラボパルパー(相川鉄工製)を用いて簡易的に分散させた後、タンクに送液した。該タンクと接続された、刃幅:4mm、溝幅:4.5mm、刃溝比:0.89のディスクを備えたシングルディスクリファイナー(1台のみ)によって、スラリーを循環させながら微細化を施した。この時、刃間距離1.0mmから運転を開始し、徐々に刃間距離を詰めながら、最終的な刃間距離を0.05mmとした。刃間距離が0.05mmに達してから、さらに流量を確認しながら運転を継続し、スラリー全量が250回ディスク部を通過した段階で、運転を終了した。続けて、高圧ホモジナイザー(ニロ・ソアビ社(伊)製NS015H)を用いて操作圧力100MPaにて10回微細化処理し、得られたセルロース微細繊維をセルロース微細繊維K(MFC-K)とした。各種繊維形状パラメータ及びレオロジー特性の分析結果を表6に示す。
日本紙パルプ商事(株)より入手した天然セルロースであるリンターパルプを用い、リンターパルプが1.5質量%となるように水に浸液させ、ラボパルパー(相川鉄工製)を用いて簡易的に分散させた後、タンクに送液した。該タンクと接続された、刃幅:2.5mm、溝幅:7.0mm、刃溝比:0.36のディスクを備えたシングルディスクリファイナー(1台のみ)によって、スラリーを循環させながら微細化を施した。この時、刃間距離1.0mmから運転を開始し、徐々に刃間距離を詰めながら、最終的な刃間距離を0.3mmとした。刃間距離が0.3mmに達してから、さらに流量を確認しながら運転を継続し、スラリー全量が90回ディスク部を通過した段階で、運転を終了した。得られたセルロース微細繊維を、ミクロフィブリル化セルローL(MFC-L)とした。各種繊維形状パラメータ及びレオロジー特性の分析結果を表6に示す。
(実施例II-1-1)
セルロース微細繊維としてMFC-Aを用いて、以下の手順にて射出成形による複合体を作製した。
1. セルロース微細繊維を吸引濾過(濾材:敷島カンバス社製 TT35)により濃縮し、固形分約20質量%のウェットケークとした。
2. 前記ウェットケークをヘキサフルオロイソプロパノール(以下、HFIPと呼称)に終濃度1体積%となるようにホモジナイザー(IKA製、商品名「ウルトラタラックスT18」)を用いて、回転数:12,000rpmにて3分間、分散処理を行った。
3. ポリアミド6(宇部興産製、1013B、融点225℃)をHFIPに1質量%で溶解させた溶解液を調製した。
4. 2及び3を、MFC-Aとポリアミド6が固形分質量比で1:9となるよう同一容器に入れ、自転・公転ミキサー(シンキー社製、あわとり練太郎 ARE-310)で2,000rpmにて、5分間混合した。
5. 4を離型フィルム(三井化学東セロ社製、X88B)上にフィルム状にキャストし、80℃のオーブンで1時間乾燥した。
6. 5を卓上粉砕機(ラボネクスト社製、ミニスピードミル MS-05)で粉砕した。
7. 6の粉末を真空乾燥機中で24時間以上乾燥させた。
8. 7を小型混練機(DSM社製、Xplore MC 15HT)にて、温度:250℃、回転数:200rpmで2分間混練した。
9. 混練終了後、射出成形機(Xplore IM12)に混練生成物を流し込み、ISO-37に準拠した多目的試験片を複合体1-Aとして作製した。
セルロース微細繊維としてMFC-Bを用いた以外は、実施例II-1-1と同様の方法で複合体を作製し、複合体1-Bを得た。得られた複合体1-Bを、前述の引張試験及び動的粘弾性測定によって評価した結果を表6に示す。
セルロース微細繊維としてMFC-Cを用いた以外は、実施例II-1-1と同様の方法で複合体を作製し、複合体1-Cを得た。得られた複合体1-Cを、前述の引張試験及び動的粘弾性測定によって評価した結果を表6に示す。
セルロース微細繊維としてMFC-Dを用いた以外は、実施例II-1-1と同様の方法で複合体を作製し、複合体1-Dを得た。得られた複合体1-Dを、前述の引張試験及び動的粘弾性測定によって評価した結果を表6に示す。
セルロース微細繊維としてMFC-Eを用いた以外は、実施例II-1-1と同様の方法で複合体を作製し、複合体1-Eを得た。得られた複合体1-Eを、前述の引張試験及び動的粘弾性測定によって評価した結果を表6に示す。
セルロース微細繊維としてMFC-Fを用いた以外は、実施例II-1-1と同様の方法で複合体を作製し、複合体1-Fを得た。得られた複合体1-Fを、前述の引張試験及び動的粘弾性測定によって評価した結果を表6に示す。
セルロース微細繊維としてMFC-Gを用いた以外は、実施例II-1-1と同様の方法で複合体を作製し、複合体1-Gを得た。得られた複合体1-Gを、前述の引張試験及び動的粘弾性測定によって評価した結果を表6に示す。
セルロース微細繊維としてMFC-Hを用いた以外は、実施例II-1-1と同様の方法で複合体を作製し、複合体1-Hを得た。得られた複合体1-Hを、前述の引張試験及び動的粘弾性測定によって評価した結果を表6に示す。
セルロース微細繊維としてMFC-Iを用いた以外は、実施例II-1-1と同様の方法で複合体を作製し、複合体1-Iを得た。得られた複合体1-Iを、前述の引張試験及び動的粘弾性測定によって評価した結果を表6示す。
セルロース微細繊維としてMFC-Jを用いた以外は、実施例II-1-1と同様の方法で複合体を作製し、複合体1-Jを得た。得られた複合体1-Jを、前述の引張試験及び動的粘弾性測定によって評価した結果を表6に示す。
セルロース微細繊維としてMFC-Kを用いた以外は、実施例II-1-1と同様の方法で複合体を作製し、複合体1-Kを得た。得られた複合体1-Kを、前述の引張試験及び動的粘弾性測定によって評価した結果を表6に示す。
セルロース微細繊維としてMFC-Lを用いた以外は、実施例II-1-1と同様の方法で複合体を作製し、複合体1-Lを得た。得られた複合体1-Lを、前述の引張試験及び動的粘弾性測定によって評価した結果を表6に示す。
ポリプロピレン製の短繊維(カット長:2.0mm、繊度:0.2T、融点160℃)と、MFC-Aを固形分質量比で80:20となるように、純水中に加え、固形分終濃度0.5質量%とした。前記スラリーを家庭用ミキサーで4分撹拌することで抄紙スラリーを調製した。
濾布(敷島カンバス社製 TT35)をセットしたバッチ式抄紙機(熊谷理機工業社製、自動角型シートマシーン 25cm×25cm、80メッシュ)に、上記調製した抄紙スラリーを目付が300g/m2となるように投入し、その後、大気圧に対する減圧度を50KPaとして抄紙(脱水)を実施した。
セルロース微細繊維としてMFC-Bを用いた以外は、実施例II-2-1と同様の方法で複合体を作製し、複合体2-Bを得た。得られた複合体2-Bを、前述の曲げ試験によって評価した結果を表7に示す。
セルロース微細繊維としてMFC-Cを用いた以外は、実施例II-2-1と同様の方法で複合体を作製し、複合体2-Cを得た。得られた複合体2-Cを、前述の曲げ試験によって評価した結果を表7に示す。
セルロース微細繊維としてMFC-Dを用いた以外は、実施例II-2-1と同様の方法で複合体を作製し、複合体2-Dを得た。得られた複合体2-Dを、前述の曲げ試験によって評価した結果を表7に示す。
セルロース微細繊維としてMFC-Eを用いた以外は、実施例II-2-1と同様の方法で複合体を作製し、複合体2-Eを得た。得られた複合体2-Eを、前述の曲げ試験によって評価した結果を表7に示す。
セルロース微細繊維としてMFC-Fを用いた以外は、実施例II-2-1と同様の方法で複合体を作製し、複合体2-Fを得た。得られた複合体2-Fを、前述の曲げ試験によって評価した結果を表7に示す。
セルロース微細繊維としてMFC-Gを用いた以外は、実施例II-2-1と同様の方法で複合体を作製し、複合体2-Gを得た。得られた複合体2-Gを、前述の曲げ試験によって評価した結果を表7に示す。
セルロース微細繊維としてMFC-Hを用いた以外は、実施例II-2-1と同様の方法で複合体を作製し、複合体2-Hを得た。得られた複合体2-Hを、前述の曲げ試験によって評価した結果を表7に示す。
セルロース微細繊維としてMFC-Iを用いた以外は、実施例II-2-1と同様の方法で複合体を作製し、複合体2-Iを得た。得られた複合体2-Iを、前述の曲げ試験によって評価した結果を表7に示す。
セルロース微細繊維としてMFC-Aを用いて、以下の手順にて射出成形による複合体を作製した。
1. ポリプロプレン製の短繊維(カット長:2.0mm、繊度:0.2T、融点160℃)を離型フィルム(三井化学東セロ社製、X88B)上に乗せ、200℃のオーブンで加熱し溶融させた。
2. 1を冷却固化させたものを、卓上粉砕機(ラボネクスト社製、ミニスピードミル MS-05)で粉砕した。
3. 密閉式プラネタリーミキサー(株式会社小平製作所製、商品名「ACM-5LVT」、撹拌羽根はフック型)中に、セルロース微細繊維とロジンエチレンオキサイド付加物(ハリマ化成株式会社社製、ロジン-ポリエチレングリコールエステル)を、セルロース微細繊維/ロジンエチレンオキサイド付加物が質量比で80/20となるように投入し、常温常圧下にて70rpmで60分間攪拌し、最後に減圧(-0.1MPa)し、40℃の温浴にセットし、307rpmで2時間、コーティング及び減圧乾燥処理を行い、粉末状のセルロース微細繊維製剤Aを得た。
4. 2及び3の粉末をセルロース微細繊維とポリプロピレンが質量比で20:80となるよう配合し、小型混練機(DSM社製、Xplore MC 15HT)にて、温度:200℃、回転数:200rpmで5分間混練した。
5. 混練終了後、射出成形機(Xplore IM12)に混練生成物を流し込み、短冊形の試験片(10mm×75mm×4mm)を複合体2-A2として作製した。
セルロース微細繊維としてMFC-Jを用いた以外は、実施例II-2-1と同様の方法で複合体を作製し、複合体2-Jを得た。得られた複合体2-Jを、前述の曲げ試験によって評価した結果を表7に示す。
セルロース微細繊維としてMFC-Kを用いた以外は、実施例II-2-1と同様の方法で複合体を作製し、複合体2-Kを得た。得られた複合体2-Kを、前述の曲げ試験によって評価した結果を表7に示す。
セルロース微細繊維としてMFC-Lを用いた以外は、実施例II-2-1と同様の方法で複合体を作製し、複合体2-Lを得た。得られた複合体2-Lを、前述の曲げ試験によって評価した結果を表7に示す。
セルロース微細繊維としてMFC-Jを用いた以外は、実施例II-2-10と同様の方法で複合体を作製した。得られた複合体を、複合体2-J2とし、前述の曲げ試験によって評価した結果を表7に示す。
12 溝
21 回転刃
22 固定刃
WB 刃幅
WG 溝幅
WL 刃間距離
Claims (26)
- 繊維形状自動分析計の測定において、
(i)繊維長100μm以上の繊維の長さ加重平均繊維長が、110μm以上500μm以下、
(ii)平均繊維径が42.5μm以下、
(iii)ファイン繊維面積比が90%以下、
(iv)繊維長100μm未満の繊維のうち、20μm以上56μm以下の繊維長を有する繊維の数頻度が97%以下、
(v)繊維長100μm以上の繊維のうち、繊維長が411μm以上である繊維の数頻度が54%以下、及び
(vi)比表面積で換算したときの平均繊維径が20~150nm、
のすべてを満たす、セルロース微細繊維。 - 平均繊維長が110μm以上500μm以下である、請求項1に記載のセルロース微細繊維。
- 繊維形状自動分析計の測定において、
(i)平均繊維長が130μm以上350μm以下、
(ii)平均繊維径が35μm以下、
(iii)ファイン繊維面積比が75%以下、
(iv)繊維長100μm未満の繊維のうち、20μm以上56μm以下の繊維長を有する繊維の数頻度が75%以下、
(v)繊維長100μm以上の繊維のうち、411μm以上の繊維長を有する繊維の数頻度が30%以下、及び
(vi)フィブリル化率が5%以下、
のすべてを満たす、請求項1に記載のセルロース微細繊維。 - 構成糖分析におけるグルコース含有率が90質量%以上である、請求項1に記載のセルロース微細繊維。
- セルロース微細繊維の5質量ppmDMSO分散液をキャスト及び乾燥して得た試料の表面の走査型電子顕微鏡(SEM)画像において、セルロース微細繊維の占める総面積に対する、占有面積が15μm2未満である極微小繊維の総占有面積の割合が10%以上80%以下である、請求項1に記載のセルロース微細繊維。
- セルロースI型の結晶構造を有する、請求項1に記載のセルロース微細繊維。
- 結晶化度が60%以上である、請求項1に記載のセルロース微細繊維。
- ハロゲン含有量が250質量ppm以下である、請求項1に記載のセルロース微細繊維。
- 白色度が50%以上である、請求項1に記載のセルロース微細繊維。
- 繊維長100μm以上の繊維の長さ加重平均繊維長が130μm以上350μm以下である、請求項1に記載のセルロース微細繊維。
- 繊維長が100μm以上の繊維のうち、繊維長が411μm以上である繊維の数頻度が30%以下である、請求項1に記載のセルロース微細繊維。
- ファイン繊維面積比が75%以下である、請求項1に記載のセルロース微細繊維。
- 繊維長100μm未満の繊維のうち、20μm以上56μm以下の繊維長を有する繊維の数頻度が30%以上75%以下である、請求項1に記載のセルロース微細繊維。
- フィブリル化率が5%以下である、請求項1に記載のセルロース微細繊維。
- 少なくとも表面が化学修飾されたセルロース微細繊維である、請求項1に記載のセルロース微細繊維。
- 化学修飾がアセチル化であり、アセチル化度が0.5~1.3である、請求項15に記載のセルロース微細繊維。
- 繊維形状自動分析計の測定において
(iv)繊維長100μm未満の繊維のうち、20μm以上56μm以下の繊維長を有する繊維の数頻度が30%以上97%以下、及び
(vi)フィブリル化率が5%以下、
をさらに満たす、請求項1に記載のセルロース微細繊維。 - 請求項1~17のいずれか一項に記載のセルロース微細繊維の製造方法であって、
前記セルロース微細繊維のハロゲン含有量が250質量ppm以下であり、前記方法が、
ハロゲン含有量が300質量ppm以下であるセルロース原料を解繊する工程を含む、セルロース微細繊維の製造方法。 - 請求項1~17のいずれか一項に記載のセルロース微細繊維と、樹脂とを含む、繊維強化樹脂。
- 前記樹脂が融点200℃以上を有する、請求項19に記載の繊維強化樹脂。
- 前記セルロース微細繊維1質量%以上を含む、請求項19に記載の繊維強化樹脂。
- 請求項1~17のいずれか一項に記載のセルロース微細繊維を含む、不織布。
- 融点300℃以下の合成繊維を50質量%以上含む、請求項22に記載の不織布。
- 前記セルロース微細繊維を1質量%以上含む、請求項22に記載の不織布。
- 請求項22に記載の不織布と前記不織布に含浸されている樹脂とを含む、繊維強化樹脂。
- セルロース微細繊維と樹脂とを含む繊維強化樹脂の製造方法であって、
請求項22に記載の不織布を熱プレスして繊維強化樹脂を得る工程を含み、
前記不織布が合成繊維を含み、前記熱プレスを、前記合成繊維の融点以上で行う、繊維強化樹脂の製造方法。
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