JP2018204147A - Composite of synthetic pulp and cellulose nanofiber and method of manufacturing the same - Google Patents

Abstract

To provide a composite consisting of synthetic pulp and cellulose nanofibers capable of providing synthetic paper having improved strength and printability, as well as paint and ink that exhibit excellent rheological characteristics, by using it as an alternative to the conventional synthetic pulp.SOLUTION: A composite consists of synthetic pulp and cellulose nanofibers of this invention comprises the synthetic pulp and the cellulose nanofibers trapped therein. The synthetic pulp is made of a resin having a MFR of 0.1 g/10 min to 200 g/10 min, and is formed by assembling a plurality of microfibrillated fibers, the microfibrillated fibers have an average fiber length of 0.05 mm to 50 mm, minimum value of fiber diameter of 0.5 μm, and maximum value of fiber diameter of 50 μm. The Canadian freeness of the synthetic pulp is 300 ml or more to 740 ml or less.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a composite of synthetic pulp and cellulose nanofiber, and a method for producing the composite.

  Synthetic pulp is used as an additive to be added to non-woven or film materials, or paints and inks.

  For example, synthetic pulp can be processed into a non-woven fabric by a wet papermaking method to obtain a synthetic paper, tea bag, filter or the like. Furthermore, synthetic paper made from synthetic pulp can be used as a recording medium for printing. For example, Patent Document 1 discloses a surface treatment method for improving the printability of synthetic paper, a laminate that is a synthetic paper subjected to the surface treatment, and a printed material using the laminate as a recording medium. .

  Regarding the use of synthetic pulp as an additive for paints and inks, for example, Patent Document 2 discloses an additive containing synthetic pulp for imparting coating properties, crack resistance and water resistance to water-based paints. ing.

Japanese Patent Laying-Open No. 2015-151649 JP, 2006-188338, A

  Synthetic paper using only synthetic pulp tends to lack paper strength, and it is necessary to add long fibers such as cellulose and synthetic resin cut fibers for reinforcement. Further, conventional synthetic paper containing synthetic pulp has poor printability, and ink transfer during printing may be insufficient. By applying the surface treatment as described in Patent Document 1 to the surface of the synthetic paper, the printing characteristics of the synthetic paper are improved, and a synthetic paper exhibiting excellent printing characteristics without such complicated surface treatment is desired. It is rare.

  In addition, when synthetic pulp alone is used as an additive such as paint or ink, particularly as a thickener, the effect may be insufficient. Therefore, Patent Document 2 also describes the combined use of synthetic pulp and other rheology control agents.

  The present invention has been made in view of the above problems, and by using as an alternative to conventional synthetic pulp, synthetic paper with improved strength and printability, paints and inks exhibiting good rheological properties, etc. It aims at providing the composite_body | complex of synthetic pulp and a cellulose nanofiber which comes to be obtained. In addition, the present invention is a composite of the above synthetic pulp and cellulose nanofiber that suppresses the aggregation and uneven distribution of the cellulose nanofiber without performing complicated manufacturing processes such as chemical treatment and mechanical treatment of the synthetic pulp and cellulose nanofiber. It is also an object to provide a method for producing a body.

The 1st aspect of this invention for solving the said subject is related with the composite_body | complex of the following synthetic pulp and a cellulose nanofiber.
[1] A resin having an MFR of 0.1 g / 10 min or more and 200 g / 10 min, an average fiber length of 0.05 mm or more and 50 mm or less, a minimum value of the fiber diameter of 0.5 μm, and a maximum fiber diameter A composite comprising a synthetic pulp having a Canadian freeness of 300 ml or more and 740 ml or less, and cellulose nanofibers captured by the synthetic pulp, wherein microfibril fibers having a value of 50 μm are aggregated.
[2] The synthetic pulp is made of a resin having an MFR of 5.0 g / 10 min to 150 g / 10 min. The average fiber length is 0.10 mm to 1.15 mm and the average fiber diameter is 15 μm to 35 μm. The composite according to [1], which is a synthetic pulp having a Canadian freeness of 300 ml or more and 740 ml or less formed by aggregating the following microfibril fibers.
[3] The composite according to [1] or [2], which is a nonwoven material.
[4] The composite according to [1] or [2], which is contained in a material for synthetic paper.
[5] The composite according to [1] or [2], which is contained in a material for paint or ink.

Moreover, the 2nd aspect of this invention for solving the said subject is related with the manufacturing method of the composite_body | complex of the following synthetic pulp and a cellulose nanofiber.
[5] A resin having an MFR of 0.1 g / 10 min or more and 200 g / 10 min, an average fiber length of 0.05 mm or more and 50 mm or less, a minimum value of the fiber diameter of 0.5 μm, and a maximum fiber diameter Stirring installed in the upper and lower stages of the lower and upper blades using synthetic pulp having a Canadian freeness of 300 ml to 740 ml and cellulose nanofibers, which is a collection of microfibril fibers having a value of 50 μm A step of causing the synthetic pulp and the cellulose nanofiber to flow by a rotational force of a lower blade in a mixer having a blade in a stirring vessel, and simultaneously stirring and mixing the synthetic pulp and the cellulose nanofiber by a shearing force of an upper blade; A method for producing a composite.

  According to the present invention, when a composite comprising a specific synthetic pulp and cellulose nanofibers captured by the synthetic pulp is used as an alternative to a conventional synthetic pulp, a synthetic paper having improved strength and printability is obtained. Be able to. Furthermore, when used as a thickener for paints and inks, paints and inks exhibiting good rheological properties can be obtained without the addition of other rheology control agents. In addition, according to the present invention, the synthetic pulp and cellulose nanofibers that suppress the aggregation and uneven distribution of the cellulose nanofibers without performing complicated manufacturing processes such as chemical treatment and mechanical treatment of the synthetic pulp and cellulose nanofibers, A method of manufacturing the composite of is provided.

It is an electron micrograph of synthetic pulp used for the composite of synthetic pulp and cellulose nanofiber concerning one embodiment of the present invention. It is an electron micrograph which shows a mode that the synthetic pulp capture | acquired the cellulose nanofiber in the composite_body | complex of the synthetic pulp and cellulose nanofiber which concern on one Example of this invention. In the composite of synthetic pulp and cellulose nanofiber according to one embodiment of the present invention shown in FIG. 2, an enlarged photograph of the synthetic pulp capturing the cellulose nanofiber is shown. It is the result of having measured the rheological characteristic about the water-based coating material of Example 10, the comparative example 7, and the comparative example 8. FIG.

1. Composite of synthetic pulp and cellulose nanofiber The composite of synthetic pulp and cellulose nanofiber according to an embodiment of the present invention is made of a resin having an MFR of 0.1 g / 10 min to 200 g / 10 min. Is from 0.05 mm to 50 mm, the minimum value of the fiber diameter is 0.5 μm and the maximum value of the fiber diameter is 50 μm, and the Canadian freeness is 300 ml or more and 740 ml or less. Synthetic cellulose and cellulose nanofibers captured by the synthetic pulp (hereinafter, may be abbreviated as “CNF”).

  Captured means that CNF is firmly fixed to the synthetic pulp to such an extent that it is not easily detached. In this specification, when a plastic bag containing a composite of synthetic pulp and cellulose nanofiber is shaken, the amount of CNF that is separated from the synthetic pulp and falls to the lower part of the plastic bag is reduced before the shaking. It is assumed that CNF is trapped in the synthetic pulp when the amount of CNF contained in the composite of cellulose and nanofiber is 5% by mass or less.

  In addition, the amount of CNF contained in the composite of synthetic pulp and cellulose nanofiber before the above-mentioned shaking is determined by decomposing the composite of synthetic pulp and cellulose nanofiber, and separating the fiber and CNF precisely. Can be measured by weighing. Thus, the separation rate can be determined by measuring the amount of separated CNF after shaking from the amount of CNF measured in advance.

  When CNF is thus captured by synthetic pulp, CNF does not separate from the synthetic pulp during use and does not aggregate. Therefore, when the composite of the synthetic pulp of the present invention and cellulose nanofiber is used as an alternative to the conventional synthetic pulp to produce a synthetic paper, a synthetic paper with improved strength and printability can be obtained. When used as a thickener for paints and inks, paints and inks exhibiting good rheological properties can be obtained without adding other rheology control agents.

(Synthetic pulp)
Synthetic pulp is a fiber having a structure in which a plurality of fine fibers made of a synthesized resin are entangled to form a thicker fiber having a branched structure (also simply referred to as “microfibril fiber”. Such a structure is simply referred to as “ Is also referred to as a “microfibril structure”), which is a fiber assembly that is assembled without being aligned in a specific direction as a whole.

  The synthesized resin is not particularly limited and various compounds can be used. However, a thermoplastic resin is preferable, and a polyolefin is more preferable. Examples of the polyolefin include homopolymers and copolymers of α-olefins having 2 to 6 carbon atoms. The copolymer may be a copolymer of two or more kinds of α-olefins having 2 to 6 carbon atoms, or may be a copolymer of an α-olefin having 2 to 6 carbon atoms and another polymerizable compound. Examples of the other polymerizable compounds include olefins other than α-olefins having 2 to 6 carbon atoms, unsaturated carboxylic acids including acrylic acid and methacrylic acid, acrylic acid esters, methacrylic acid esters, and vinyl acetate. included. The copolymer may be a graft copolymer obtained by grafting an unsaturated carboxylic acid monomer with a peroxide to the homopolymer or copolymer described above. The homopolymer or copolymer is preferably crystalline.

  Preferred examples of the α-olefin having 2 to 6 carbon atoms include ethylene, propylene, 1-butene, 3-methyl-1-butene and 4-methyl-1-butene. Examples of crystalline homopolymers or copolymers produced from materials containing these α-olefins having 2 to 6 carbon atoms include linear low density polyethylene and elastomers (ethylene-α-olefin copolymers). Low density polyethylene, medium density polyethylene, high density polyethylene, ultrahigh molecular weight polyethylene, ethylene-methacrylic acid copolymer, acid-modified polyethylene with maleic acid or acrylic acid, polypropylene, polybutene, poly-3-methylbutene, and poly-4 -Methylbutene, as well as mixtures thereof.

  The synthesized resin preferably has a molecular weight distribution (Mw / Mn) (value calculated using a molecular weight in terms of polystyrene by GPC method using a TSKgel column) of 1.5 or more and 3.5 or more. Further, the synthesized resin preferably has a melt flow rate (MFR: a value measured at 190 ° C. by ASTM D1238 at a load of 2.16 kg) of 0.1 g / 10 min to 200 g / 10 min, and 5.0 g It is more preferably / 10 min or more and 150 g / 10 min or less. Furthermore, the upper limit is preferably 110 g / 10 min or less, particularly preferably 100 g / 10 min or less.

  The synthesized resin is preferably made of polyethylene, and particularly preferably made of polyethylene having a melt flow rate of 5.0 g / 10 min to 150 g / 10 min.

  The method for producing the synthesized resin is not particularly limited, and those produced by known methods can be used.

  Synthetic pulp may contain various compounds other than microfibril fibers (hereinafter, also simply referred to as “other compounds”) as long as CNF distribution unevenness is not extremely likely to occur. For example, synthetic pulp includes antibacterial agents, heat stabilizers, weather stabilizers, various stabilizers, antioxidants, dispersants, antistatic agents, slip agents, antiblocking agents, antifogging agents, lubricants as the above other compounds. , Compounds known as dyes, pigments, natural oils, synthetic oils, waxes, fillers, and the like. The synthetic pulp may contain a plurality of types of these compounds, and the content thereof can be appropriately selected according to the purpose of containing these compounds.

  In the microfibril fiber, the average value of the distance between the end portions set to be the longest among the distances between the end portions of one fiber (hereinafter referred to as “average fiber length”) is 0.05 mm. It may be 50 mm or less, preferably 0.1 mm or more and 10 mm or less, more preferably 0.1 mm or more and 1.15 mm or less. If the average fiber length is within this range, it is preferable to use synthetic pulp because it has an appropriate bulkiness and a sufficient restoring force when pressure is applied.

  The average fiber length can be determined by the following procedure.

  The microfibril fibers constituting the synthetic pulp are classified every 0.05 mm using the longest length. Thereafter, the actual fiber length of the microfibril fibers included in each class (length) and the number of microfibril fibers included in each class are measured. The measurement may be performed for 12000 to 13000 fibers. Thereafter, the number average fiber length Ln (mm) of each class is obtained from the above measurement result by the following formula.

Ln = ΣL / N
L: Actual fiber length (mm) of microfibril fibers included in one class
N: Number of microfibrils contained in one class

  Then, the average fiber length (mm) of the microfibril fiber which comprises a synthetic pulp is calculated | required with the following formula | equation.

Average fiber length = Σ (Nn × Ln ³ ) / Σ (Nn × Ln ² )
Nn: Number of microfibrils contained in each class

  The measured fiber length is, for example, by dispersing synthetic pulp in water so as to have a concentration of 0.02% by mass, and using an automatic fiber measuring machine (product name: FiberLab-3.5) manufactured by Metso Automation, Finland. It can be determined by measuring the length of each fiber constituting the synthetic pulp. In the measuring machine, a fiber flowing through a capillary is irradiated with xenon lamp light, and a video signal is collected by a CCD (charge coupled device) sensor and image analysis is performed.

  The microfibril fiber preferably has a minimum diameter (hereinafter also simply referred to as “fiber diameter”) of 0.5 μm or more, and a maximum fiber diameter of 50 μm or less. The average fiber diameter is more preferably 15 μm or more, and more preferably 35 μm or less. If the fiber diameter is within this range, it is preferable because the fiber has an appropriate bulkiness when aggregated and has a sufficient restoring force when pressure is applied.

  The fiber diameter can be measured by observing one fiber or one fiber with a microscope such as an optical microscope or an electron microscope.

  Specifically, the maximum value and the minimum value of the fiber diameter can be measured as follows.

  Synthetic pulp is observed with a digital HF microscope VH8000 manufactured by Keyence Co., Ltd. at a magnification of 100 times, and 100 microfibril fibers observed so that the fiber diameter is 10 μm or more are randomly selected. The fiber diameter of the selected microfibril fiber is measured, and the maximum value among the measured values is defined as “the maximum value of the fiber diameter”.

  Synthetic pulp is observed with a scanning electron microscope JSM6480 manufactured by JEOL Ltd. at a magnification of 3000 times, and 100 microfibril fibers are randomly selected so that the fiber diameter is less than 10 μm. The fiber diameter of the selected microfibril fiber is measured, and the smallest value among the measured values is defined as “the minimum value of the fiber diameter”.

  The average fiber diameter can be measured using a fiber image analyzer such as Valmet FS5 manufactured by Valmet Automation.

  For example, as shown in FIG. 1, the microfibril fiber has a branched structure in which one fiber is branched into a large number. The branched structure can be confirmed by observing with an optical microscope or an electron microscope. In addition, FIG. 1 is the photograph which observed the synthetic pulp by 500 times with the scanning electron microscope JSM6480 by JEOL.

  When a large number of microfibril fibers having a branched structure are aggregated to form a synthetic pulp, the fibers are not aligned in a specific direction, and the branched fibers are easily entangled with each other or the branched portions are easily crossed. Due to the entanglement and crossing, many holes are formed in the synthetic pulp. In addition, due to the entanglement and intersection, the holes are not easily crushed even when pressure is applied. As a result, the synthetic pulp can retain the moisture that has entered the pores as it is. For example, when a sheet-like fiber assembly is used, a composite of synthetic pulp and cellulose nanofibers with high water absorption It can be.

  From the viewpoint of making a composite of synthetic pulp with higher water absorption and cellulose nanofiber, synthetic pulp is Canadian freeness measured in accordance with JISP 8121-2 (hereinafter sometimes abbreviated as “CSF”). Is 300 ml or more and 740 ml or less, and preferably 340 ml or more and 700 ml or less.

  The CSF can be obtained by the following procedure.

  Synthetic pulp having an absolute dry weight of 24 g is weighed, 2000 ml of water is added to a concentration of about 1.2%, and it is disaggregated to 30000 revolutions (10 minutes) by a disaggregator specified in JISP8220-1. The completely disaggregated microfibril fiber is diluted to a concentration of about 0.3%, and the water temperature is set to 20.0 ± 0.5 ° C. 1000 ml of the disaggregated pulp slurry is weighed, and the amount of drainage discharged from the side pipe is read using a Canadian standard freeness tester.

(Method for producing synthetic pulp)
Synthetic pulp can be produced by various methods, but can usually be produced by a flash method. The flash method means that a high-pressure resin solution in which a resin is dissolved in a solvent is ejected under reduced pressure to volatilize the solvent to form fibers made of the resin, and if necessary, a Waring blender or a disc refiner In this method, the formed fibers are cut and beaten. The flash method is preferable because a synthetic pulp having high strength can be obtained when a nonwoven fabric is used. In particular, a method of flushing a polyolefin solution dispersed in an aqueous medium in the presence of a suspending agent, as described in JP-A-48-44523, is a fiber having a randomly branched shape. A synthetic pulp having the above resin is obtained, and such a synthetic pulp is preferable because a nonwoven fabric with higher strength can be obtained.

  In the flash method, a thermoplastic resin, which is a material of the microfibril resin constituting the synthetic pulp, is dissolved, and a suspension and water are added to form an emulsion. At the same time, the emulsion is ejected (flashed) under reduced pressure. Vaporizing the solvent.

  In the first step of the flash method, the thermoplastic resin is dissolved in a solvent capable of dissolving the thermoplastic resin, and a suspension and water are added to form an emulsion.

  Examples of the solvent include saturated hydrocarbon solvents including butane, pentane, hexane, heptane, octane and cyclohexane, aromatic solvents including benzene and toluene, halogens including methylene chloride, chloroform and carbon tetrachloride. Carbonized carbons are included. From these solvents, the one that dissolves the thermoplastic resin, which is the material of the microfibril resin that constitutes the synthetic pulp to be produced, and that does not easily remain in the aggregate of fibers that have been volatilized during flashing should be selected as appropriate. That's fine.

  Examples of the suspending agent include hydrophilic resins including polyvinyl alcohol, polyethylene glycol, polypropylene glycol, polyacrylate, gelatin, tragacanth gum, starch, methylcellulose, carboxymethylcellulose and the like. Moreover, the said hydrophilic resin and general nonionic surfactant, a cationic surfactant, or an anionic surfactant can also be used together. The suspending agent uniformly mixes the thermoplastic resin, the solvent, and water, so that the emulsion is stabilized, and the fibers can be stably cut and beaten after flushing in water.

  The addition amount of the suspending agent is preferably such that the suspending agent is 0.1% by mass or more and 5% by mass or less in the fiber. It is preferable to adjust the amount of the suspending agent as appropriate, such as adding a larger amount in the production process when an operation is performed to remove a part of the added suspending agent. As a standard of the addition amount, it can be 0.1 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin.

  In the second step of the flash method, the emulsion obtained in the first step is heated to a temperature of 100 ° C. to 200 ° C., preferably 130 ° C. to 150 ° C., and the pressure is 0.1 MPa. The pressure is set to 5.0 MPa or less, preferably 0.5 MPa or more and 1.5 MPa or less. Thereafter, the heated and pressurized emulsion is ejected (flushed) from the nozzle into a decompressed space, and at the same time, the solvent is vaporized and volatilized. The decompressed space preferably has a pressure of 1 kPa to 95 kPa. The decompressed space is preferably an inert atmosphere such as a nitrogen atmosphere. In the present invention, “pressure” means absolute pressure.

  Through the above process, indefinite-length microfibril fibers having a branched structure made of the thermoplastic resin are obtained. The microfibril fibers thus obtained are preferably cut and beaten with a Waring blender or disc refiner so that the average fiber length is in the above-mentioned range. At this time, it is preferable to perform the above-mentioned cutting and beating by dissolving or dispersing the microfibril fibers in water to form a water slurry having a concentration of 0.5 g / L or more and 5.0 g / L or less.

  At this time, for example, the fiber diameter and Canadian freeness of the microfibril resin can be adjusted to a desired level by selecting the disc refiner blade type, rotation speed, or screen diameter according to predetermined conditions. Can do.

  The microfibril resin may be subjected to a surface treatment with a nonionic surfactant or polypropylene glycol in order to increase hydrophilicity. Examples of the microfibril resin subjected to hydrophilic treatment include microfibril resins used for synthetic pulps as disclosed in JP-A-63-235575 and JP-A-63-66380.

  The microfibril resin thus obtained can be dried and then opened with a mixer or the like to obtain a synthetic pulp.

  According to the method demonstrated above, the microfibril resin which has a branched structure, and the synthetic pulp which the said microfibril fiber aggregates can be manufactured preferably. In addition, when a synthetic pulp contains the other compound mentioned above, it is preferable to add the said other compound to the said emulsion. By doing in this way, the said other compound fully disperse | distributes in a synthetic pulp, and it becomes possible to hold | maintain the effect by the said other compound for a long period of time.

(Cellulose nanofiber (CNF))
Cellulose nanofibers can be obtained by refining (defibrating) pulp fibers. As a pulp fiber used as a raw material, for example,
Hardwood bleached kraft pulp (LBKP), hardwood unbleached kraft pulp (LUKP), etc. Hardwood kraft pulp (LKP), softwood bleached kraft pulp (NBKP), softwood kraft pulp (NKP), etc. Chemical pulp of
Stone Grand Pulp (SGP), Pressurized Stone Grand Pulp (PGW), Refiner Grand Pulp (RGP), Chemi Grand Pulp (CGP), Thermo Grand Pulp (TGP), Grand Pulp (GP), Thermo Mechanical Pulp (TMP), Mechanical pulp such as chemi-thermomechanical pulp (CTMP) and bleached thermomechanical pulp (BTMP);
Waste paper pulp made from tea waste paper, craft envelope waste paper, magazine waste paper, newspaper waste paper, leaflet waste paper, office waste paper, corrugated waste paper, Kami white waste paper, Kent waste paper, imitation waste paper, lottery waste paper, waste paper waste paper, etc .;
Examples include deinked pulp (DIP) obtained by deinking waste paper pulp. These may be used singly or may be used in combination of plural kinds as long as the effects of the present invention are not impaired.

  There is no limitation in particular in the pulp fiber used as the raw material of a cellulose nanofiber. For example, when the composite of the present invention is used as a material for synthetic paper, chemical pulp or mechanical pulp is preferable from the viewpoint of the finish such as the color when it becomes synthetic paper and the strength. When the composite of the present invention is used as an additive such as a paint, chemical pulp or mechanical pulp is preferable from the viewpoint of easy drying of the paint.

  The pulp fiber may optionally contain other paper-making chemicals as long as the effects of the present invention are not impaired.

  Examples of other papermaking chemicals include pigments, dyes, fillers, sizing agents, abrasion resistance improvers, water resistance agents, surfactants, waxes, rust preventives, conductive agents, and paper powder fall-off prevention agents. . These may be used singly or may be used in combination of plural kinds as long as the effects of the present invention are not impaired.

  Examples of the defibrating method by mechanical treatment include a grinder method in which pulp fibers are ground between rotating grindstones, a grinding method using a homogenizer, a ball mill, a roll mill, a cutter mill, and the like.

  As a fibrillation method by mechanical treatment, a grinder method in which pulp fibers are ground between rotating grindstones is preferable from the viewpoint that cellulose nanofibers can be obtained more easily and reliably.

  As a grinder method for grinding between rotating grindstones, for example, a grinding treatment method using a stone mill grinder can be used. Specifically, by passing the pulp fibers through the rubbing part of a stone mill, the pulp fibers are gradually ground by impact, centrifugal force, shearing force, etc., without chemically changing. A uniform cellulose nanofiber can be obtained.

  Further, the pulp fiber may be subjected to preliminary beating before defibrating.

  Specifically, it is preferable to proceed with defibration step by step, and in particular pre-beating treatment of unbeaten raw pulp in a so-called viscous beater such as a Niagara beater until the Canadian freeness is 30% or less of the starting raw material. After that, it is efficient in the nanocellulosic treatment to obtain cellulose nanofibers that can impart gas barrier properties by performing a fibrillation treatment until the cellulose nanofibers are obtained by a grinder method that is ground between rotating grindstones. Therefore, it is preferable.

  The water retention of the cellulose nanofiber is preferably 400% or more, and more preferably 430% or more. If the water retention of cellulose nanofibers is less than the lower limit, the dispersibility of cellulose nanofibers in water may be insufficient. On the other hand, the water retention of the cellulose nanofiber is preferably 800% or less, and more preferably 500% or less. If the water retention of cellulose nanofibers exceeds the above upper limit, it may take a long time in the natural drying step. The water retention (%) of the cellulose nanofibers is determined by JAPAN TAPPI No. 26 is measured.

2. Method for producing composite of synthetic pulp and cellulose nanofiber The composite of synthetic pulp and cellulose nanofiber is obtained by mixing the above-described microfibril resin or the above-described microfibril resin and CNF. Can be manufactured. The method of mixing is not particularly limited. For example, after forming synthetic pulp into a sheet, a method of spraying solution-like CNF, a method of mixing fluffed synthetic pulp and CNF with a mixer, or the like A method in which synthetic pulp and CNF are crushed while being lowered in the container and laminated, a method of producing a synthetic pulp in which CNF is captured by mixing microfibril resin or synthetic pulp and CNF with a mixer or the like is used. be able to. A method in which synthetic pulp and CNF are mixed with a mixer or the like, or a method in which fluffed synthetic pulp and CNF are simultaneously crushed and lowered in a container and laminated is preferable.

  Among these, the method of mixing microfibril resin or synthetic pulp and CNF with a mixer etc. is preferable. In particular, it is possible to produce a composite that suppresses the aggregation and uneven distribution of CNF without performing complicated manufacturing processes such as chemical treatment and mechanical treatment of synthetic pulp and CNF. A method in which the microfibril resin or synthetic pulp and CNF are caused to flow by the rotational force of the lower blade and the both are stirred and mixed by the shear force of the upper blade in a mixer having a stirring blade in the stirring vessel is preferable. According to the knowledge of the present inventors, by mixing with a mixer having stirring blades installed in the upper and lower two stages, the composite pulp sufficiently captures CNF and more uniformly disperses CNF. The body can be manufactured. As the process, wet synthetic pulp before drying and CNF in an aqueous solution state are mixed and combined by the above method and then dried. Further, CNF in an aqueous solution state may be added to a synthetic pulp that has been dried and fluffed in advance to form a mixed composite, and then dried again.

  The peripheral speed of the lower blade at this time is preferably 30 m / s or more and 100 m / s or less, more preferably 40 m / s or more and 80 m / s or less, and 50 m / s or more and 70 m / s or less. Is more preferable. On the other hand, the rotational speed of the upper blade is coaxial with the lower blade and may be the same peripheral speed. When the peripheral speed of the lower blade can be changed by two axes or the like, the peripheral speed can be changed within the range of the peripheral speed of the lower blade. The mixing time is preferably 3 minutes or longer and 30 minutes or shorter, more preferably 5 minutes or longer and 20 minutes or shorter, and further preferably 10 minutes or longer and 15 minutes or shorter.

  Examples of the mixer having the stirring blades installed in the upper and lower two stages include a Henschel type mixer. In particular, an FM mixer, a CP mixer, a cyclomix (R) CLX high-speed shear mixer manufactured by Nippon Coke Industries, Ltd. are preferable. Among these, an FM mixer manufactured by Nippon Coke Kogyo Co., Ltd., which can sufficiently perform shearing and mixing is preferable.

3. Application of Composite The composite of synthetic pulp and CNF of the present invention can be used for various known applications as an alternative to conventional synthetic pulp. The composite of the synthetic pulp and CNF of the present invention can be formed into various shapes, for example, can be formed into a nonwoven fabric. Filters such as tea bag paper, coffee bag paper, dashi pack paper, air filters, masks, water filters, wine filters, beer filters, juice filters, etc. by using the composite of the present invention as a nonwoven fabric; food wrapping paper Packaging materials such as deoxidized material wrapping paper, medical wrapping paper, insect proof wrapping paper; synthetic paper, wallpaper, moisture permeable waterproof sheet, heat resistant board, bran paper, shoji paper, greeting card, brochure, business card, book cover, envelope Cards, sheets and labels such as lamp shades, label paper, printing paper, poster paper, etc .; housing materials such as cement particle trapping materials and thixotropic agents; top sheets and absorbent binders for disposable diapers, napkins and sheets Sanitary materials such as fibers, disposable towels, wipers, tissue binder fibers, degreased paper, and sterilized paper ; Humidifier steam stripped material, volatilization materials such as fragrances core; and food trays stationery supplies and large parts cushioning material, automotive a wide variety of binder fiber or the like of the door panel can be suitably used.

  In addition, in the said use, a nonwoven fabric may be comprised only from the composite_body | complex of the synthetic pulp of this invention, and CNF, and the other fiber may be mixed with the composite_body | complex of this invention.

(Material for synthetic paper)
The composite of synthetic pulp and CNF of the present invention can be used as a material for synthetic paper as an alternative to conventional synthetic pulp. Examples of such synthetic paper include “synthetic pulp paper” which is produced by a normal paper machine using the composite of the present invention as a raw material instead of pulp and adding a binder if necessary. Although there is no particular limitation on the composite used as the material for the synthetic paper, the raw material resin for the synthetic pulp contained in the composite is a polyolefin-based resin, for example, a resin composed of an ethylene-based, propylene-based, or methylpentene-based polymer, For these, a resin made of a copolymer with ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, or the like can be used. These resins can be used alone or in combination.

(Material for paint or ink)
The composite of synthetic pulp and CNF of the present invention may be contained in a material for paint or ink. As with conventional synthetic pulp, the composite of the present invention can also be used as an additive for paints or inks, particularly as a thickener. Although there is no restriction | limiting in particular in the kind of coating material or ink, Use from a water system is preferable from a viewpoint of the affinity and dispersibility of the composite_body | complex of this invention.

  When adding the composite of this invention to a coating material or an ink, it is preferable to add in 0.1-5.0 mass% with respect to the mass of a coating material or an ink. If the addition amount is within the above range, the dispersibility of the paint or ink is not impaired while adjusting the rheological properties of the paint or ink.

  The paint or ink containing the composite of the present invention contains 20 to 40% by mass of pigment together with the composite. The amount of the pigment is more preferably 25 to 35% by mass. There are no particular limitations on the type of pigment, and rust preventive paints, white pigments, extender pigments, colored pigments, and the like can be used. Specific examples of pigments include anticorrosion paints such as zinc chromate, zinc oxide, and zinc phosphate, titanium oxide, ultrafine titanium oxide, lead white, basic lead sulfate, basic lead silicate, zinc white, and zinc sulfide. , White pigments such as antimony trioxide, calcium composite, calcium carbonate, barium sulfate, alumina white, silica, diatomaceous earth, kaolin, talc, organic bentonite, white carbon and other extender pigments, carbon black, yellow lead, molybdenum red, Examples thereof include colored pigments such as bengara, yellow iron oxide, titanium oxide, iron black, ocher, shena, amber, green clay, Mars violet, cadmium yellow, cadmium red, cadmium red, cadmibon yellow, ultramarine blue, and bitumen. In particular, it is preferable that the pigment is an ultrafine particle having an average particle size of 100 nm or less because transparency can be imparted to the coating film and the writing site.

  In addition to the above-mentioned color pigments, paints and inks can be used for heat insulating / heat shielding pigments (hollow silica gel, ceramic), lubricating pigments (silicon), antibacterial pigments (platinum, silver), thermal conductive pigments (diamonds), deodorizing pigments ( Functional pigments such as deodorized zeolite), high-efficiency radiation (far red / heat radiation) pigments (alumina, magnet yarn, etc.), anti-wear pigments (ceramics), and high-intensity pigments (metals such as aluminum) may be included. The total content of the functional pigment and the color pigment is preferably within the above range.

  When the paint is an aqueous paint composition, it contains a water-based resin. The water-based resin used is not limited as long as it can disperse the pigment. For example, a resin having a form such as water solubility, dispersion, emulsion, or microgel can be used.

  More specifically, the water-based resin is exemplified by acrylic resin, alkyd resin, polyester resin, polyurethane resin, acrylic urethane resin, blocked isocyanate, fluorine resin, epoxy resin, epoxy acrylate resin, phenol resin, melamine resin, vinyl. Resin, polyamide resin, cellulose resin, and the like.

  Furthermore, the water-based resin used in the aqueous coating composition includes compounds that can potentially form the resin by polymerization or crosslinking, so-called monomers and oligomers.

  EXAMPLES Hereinafter, although an Example etc. demonstrate this invention further more concretely, the scope of the present invention is not limited to these Examples etc.

(Examples 1-8)
SWP (registered trademark) EST-2 manufactured by Mitsui Chemicals, Inc., which is a synthetic pulp having a CSF of 400 ml, composed of microfibril fibers having an average fiber length of 0.9 mm, a fiber diameter of 30 μm, and an MFR of 7.0 g / 10 min. Or SWP ESS-5 manufactured by Mitsui Chemicals, Inc., which is a synthetic pulp having a CSF of 300 ml, made of microfibrils having an average fiber length of 0.1 mm, a fiber diameter of 15 μm, and an MFR of 100 g / 10 min. B (conifer bleached chemical pulp) or C (mechanical pulp), which is cellulose nanofiber (CNF) manufactured by Co., Ltd., is used so as to have the composition shown in Table 1, mixed with a pulverizing and mixing dryer, and dried. Thus, a composite of synthetic pulp and cellulose nanofiber was produced. EST-2 and ESS-5 have an average fiber diameter in the range of 1 to 50 μm and have a branched structure.

  Mixing was performed using an FM mixer FM20C / I manufactured by Nippon Coke Industries, and the stirring blades were changed as necessary. A0 / Z0 was used as a stirring blade.

  Each of the obtained composites was put in a plastic bag, and the particles separated by shaking were measured. The mass of the separated particles was divided by the mass of CNF used for the production of the composite to obtain the CNF separation rate.

(Comparative Examples 1 and 2)
Polyethylene shortcut fibers were used instead of synthetic pulp, combined with CNF so as to have the composition shown in Table 2, and mixed in the same manner as in the above examples by a pulverizing and mixing dryer (FM mixer FM20C / I manufactured by Nihon Coke Industries). . The crushed material used did not have a microfibril structure, nor did it have a branched structure.

(Comparative Examples 3 and 4)
EST-2 or ESS-5 was used as the synthetic pulp, and B (conifer bleached chemical pulp) was used as the CNF, and they were mixed so as to have the composition shown in Table 2. The synthetic pulp and CNF were mixed using a blender mixer (Comparative Example 3) or a tumbler mixer (Comparative Example 4), respectively, instead of the FM mixer.

  The composite obtained in each of Comparative Examples 1 to 4 was put in a plastic bag, and the particles separated by shaking were weighed. The mass of the separated particles was divided by the mass of CNF used for the production of the composite to obtain the CNF separation rate.

  By the type of microfibril resin and CNF used for the production of the composite of synthetic pulp and cellulose nanofiber, the respective amount (parts by mass), the production method (type of mixer, stirring speed and mixing time), and the above shaking Tables 1 and 2 show the obtained CNF separation rates.

  EST-2 or ESS-5, which is a synthetic pulp having a multi-branched structure as a synthetic pulp and having a microfibril structure, using an FM mixer that generates a shear force by an upper blade in addition to a flow composed of rotational force by a lower blade It was found that synthetic pulp and CNF can be mixed efficiently and uniformly, and the fibers can capture CNF (Examples 1 to 8).

  CNF could also be mixed and compounded in the same manner regardless of the difference in the pulp as the raw material.

  On the other hand, it was difficult to efficiently and uniformly mix CNF with a polyethylene shortcut fiber with few branch structures and few fibrils. In addition, CNF retention was poor, and a lot of CNF was separated, and CNF itself was aggregated as a large mass (Comparative Examples 1 and 2).

  Moreover, when a general mixer was used for mixing, EST-2 or ESS-5 and CNF were uniformly mixed, and CNF could not be held in synthetic pulp (Comparative Examples 3 and 4).

  FIG. 1 is an electron micrograph of the composite pulp used in Example 1 taken with a scanning electron microscope JSM6480 manufactured by JEOL Ltd. at a magnification of 500 times.

  FIG. 2 is an electron micrograph of the composite of synthetic pulp and cellulose nanofibers of Example 1 taken with a scanning electron microscope JSM6480 manufactured by JEOL Ltd. at 500 times after shaking as described above. FIG. 3 is an electron micrograph taken with the magnification of FIG. 2 increased to 5000 times. 1 to 3, it can be seen that in the composite of the present invention, the surface of the synthetic pulp is uniformly covered with cellulose nanofibers to form a composite, and the synthetic pulp captures CNF.

Example 9
Using the composite obtained in Example 1, synthetic paper having a basis weight of 20 g / m ³ was prepared by hand using a square paper machine. The synthetic paper had a tensile strength of 10 N / 15 mm, and the strength as paper was sufficient. Moreover, when the printability was confirmed by writing characters with a water-based ballpoint pen, it was confirmed that there was sufficient suitability.

(Comparative Example 5)
Using the mixture obtained in Comparative Example 3, a synthetic paper having a basis weight of 20 g / m ³ was prepared by hand using a square paper machine. The synthetic paper had a tensile strength of 1.5 N / 15 mm, and sufficient strength as paper was not obtained. Further, agglomerated foreign matters (aggregates of CNF) were observed on the surface of the paper, and a satisfactory formation could not be achieved. Furthermore, even if a character was written with a water-based ballpoint pen, it repelled ink and was not printable.

(Comparative Example 6)
In the same manner as in Example 1, only synthetic pulp (SWP EST-2) was pulverized and dried without using CNF to obtain uncomplexed fibers. Using the obtained fibers, handmade paper was prepared with a square paper machine in the same manner as in Example 9. Synthetic pulp alone has poor water dispersibility, and it has not been possible to obtain paper with a uniform texture. Moreover, when the tensile strength was measured, it was 1 N / 15 mm, and the paper strength was not sufficient.

(Example 10 and Comparative Examples 7 and 8)
The composite obtained in Example 5 was added to and mixed with a commercially available acrylic water-based paint, and the rheological properties of the paint were measured with a rheometer. In Comparative Example 7, a single SWP ESS-5 that was not combined was used, and in Comparative Example 8, the mixture obtained in Comparative Example 4 was dried and pulverized. The rheological properties were measured. The result is shown in FIG.

  As is clear from FIG. 4, in Comparative Examples 7 and 8, a sufficient thickening effect is not obtained, but in Example 10, the viscosity of the system is increased, and the composite has an effect as a thickening agent. I was able to confirm.

  The composite of synthetic pulp and cellulose nanofibers of the present invention can be used as a substitute for conventional synthetic pulp to produce synthetic paper with improved strength and printability, and paints and inks that exhibit good rheological properties. Can be obtained. Moreover, the manufacturing method of the composite_body | complex of this invention suppresses agglomeration and distribution unevenness of CNF, without performing complicated manufacturing processes, such as a chemical treatment and mechanical treatment of synthetic pulp and cellulose nanofiber, and high-quality synthetic pulp and This makes it possible to produce a large amount of a composite with cellulose nanofibers at low cost. These are expected to contribute to the further spread of composites of synthetic pulp and cellulose nanofibers.

Claims (6)

The average fiber length is 0.05 mm or more and 50 mm or less, the minimum value of the fiber diameter is 0.5 μm, and the maximum value of the fiber diameter is made of a resin having an MFR of 0.1 g / 10 min or more and 200 g / 10 min. A synthetic pulp having a Canadian freeness of 300 ml or more and 740 ml or less, comprising a collection of 50 μm microfibril fibers;
Cellulose nanofibers trapped in the synthetic pulp;
A complex containing   The synthetic pulp is made of a resin having an MFR of 5.0 g / 10 min to 150 g / 10 min, an average fiber length of 0.10 mm to 1.15 mm, and an average fiber diameter of 15 μm to 35 μm. The composite according to claim 1, wherein the composite is a synthetic pulp formed by aggregating microfibril fibers and having a Canadian freeness of 300 ml to 740 ml.   The composite according to claim 1 or 2, which is a nonwoven material.   The composite according to claim 1 or 2, which is contained in a material for synthetic paper.   The composite according to claim 1 or 2, which is contained in a material for paint or ink. The average fiber length is 0.05 mm or more and 50 mm or less, the minimum value of the fiber diameter is 0.5 μm, and the maximum value of the fiber diameter is made of a resin having an MFR of 0.1 g / 10 min or more and 200 g / 10 min. A synthetic pulp having a Canadian freeness of 300 ml or more and 740 ml or less, comprising a collection of 50 μm microfibril fibers;
Using cellulose nanofiber,
A mixer having stirring blades installed in two upper and lower stages of a lower blade and an upper blade in a stirring vessel, causing the synthetic pulp and the cellulose nanofibers to flow by the rotational force of the lower blade, and simultaneously by the shearing force of the upper blade. Stirring and mixing the synthetic pulp and the cellulose nanofibers,
A method for producing a composite.