Fibrous cellulose composite resin, its manufacturing method, and resin reinforcing material

Abstract

To provide a fibrous cellulose composite resin having high strength, a manufacturing method thereof, and a resin reinforcing material capable of significantly improving the strength of the resin.SOLUTION: The fibrous cellulose composite resin contains fibrous cellulose including microfiber cellulose, resin, and acid-modified resin, in which the microfiber cellulose has an average fiber width of 0.1 μm or more, an average fiber length of 0.02 to 2.0 mm, and a degree of fibrillation of 1.0% or more, and a hydroxyl group is substituted with a carbamate group and the carbamate group is ionically bonded to an acid group of the acid-modified resin. Further, for producing the fibrous cellulose composite resin by fibrillating cellulose raw material to obtain the microfiber cellulose, and then by kneading the microfiber cellulose and the resin, the fibrillation is performed so that the microfiber cellulose has the average fiber width of 0.1 μm or more, the average fiber length is 0.02 to 2.0 mm, and the degree of fibrillation is 1.0% or more, the hydroxyl group of the cellulose fiber is substituted with a carbamate group, and the acid-modified resin is added.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a fibrous cellulose composite resin, a method for producing the same, and a reinforcing material for resins. [Background technology]

[0002] In recent years, fine fibers such as cellulose nanofibers and microfiber cellulose (microfibrillated cellulose) have been attracting attention for their use as reinforcing materials for resins. However, because fine fibers are hydrophilic while resins are hydrophobic, there has been a problem with the dispersibility of the fine fibers when using them as reinforcing materials for resins. Therefore, the present inventors have proposed substituting the hydroxyl groups of the fine fibers with carbamate groups (see Patent Document 1). This proposal improves the dispersibility of the fine fibers, thereby improving the reinforcing effect of the resin. However, even now, further improvements in the reinforcing effect are desired, and various studies are ongoing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-1876 Summary of the Invention [Problem to be solved by the invention]

[0004] The main problem to be solved by the present invention is to provide a high-strength fibrous cellulose composite resin, a method for producing the same, and a resin reinforcing material that can significantly improve the strength of the resin. [Means for solving the problem]

[0005] Previous developments, such as those described in the above patent documents, focused on the modification of fine fibers, and among the many modification methods available, such as esterification, etherification, amidation, and sulfidation, it was discovered that the introduction of carbamate (carbamation) was superior. In contrast, the present invention does not focus on the introduction of carbamate, but rather, through various tests conducted on the premise of the introduction of carbamate, it was discovered and arrived at the idea that the above-mentioned problems could be solved by investigating the physical properties of fine fibers and other substances mixed into the fine fibers and resin. The means that led to this idea are as follows.

[0006] (Means described in claim 1) The composition comprises fibrous cellulose, a resin, and an acid-modified resin, The fibrous cellulose includes microfibrous cellulose in which some or all of the hydroxyl groups have been substituted with carbamate groups, acid groups of the acid-modified resin ionically bond with some or all of the carbamate groups of the microfibrous cellulose; The microfiber cellulose has an average fiber length of 0.02 to 2.0 mm and an average fiber diameter of 0.1 to 15 μm, The fiber length of the microfiber cellulose is 20% or more of which is 0.2 mm or less, The degree of substitution of the carbamate group is 0.05 to 0.5, and the crystallinity of the microfibrous cellulose is 50 to 95%. A fibrous cellulose composite resin characterized by:

[0007] (Means described in claim 2) The acid-modified resin is a maleic anhydride-modified resin. The fibrous cellulose composite resin according to claim 1.

[0008] (Means described in claim 3) The content of the microfibrous cellulose in the fibrous cellulose is 60 to 100% by mass, The maleic anhydride-modified resin is contained in an amount of 1 to 200 parts by mass per 100 parts by mass of the microfiber cellulose. The fibrous cellulose composite resin according to claim 2. (Means described in claim 4) The aspect ratio of the microfiber cellulose is 2 or more. 4. The composite resin according to claim 1.

[0009] (Means described in claim 5) A cellulose raw material is defibrated to form microfibrous cellulose in which some or all of the hydroxyl groups have been substituted with carbamate groups, and this microfibrous cellulose is kneaded with a resin to produce a fibrous cellulose composite resin, The degree of substitution of the carbamate group is set to 0.05 to 0.5, and the crystallinity of the microfibrous cellulose is set to 50 to 95%, The defibration is carried out so that the microfibrous cellulose has an average fiber length of 0.02 to 2.0 mm and an average fiber diameter of 0.1 to 15 μm, The fiber length of the microfiber cellulose is set to 20% or more of which are 0.2 mm or less, adding an acid-modified resin prior to or during the kneading, and ionic bonding between the acid groups of the acid-modified resin and some or all of the carbamate groups of the microfibrous cellulose; A method for producing a fibrous cellulose composite resin, comprising:

[0010] (Means described in claim 6) The aforementioned Replacement is carried out prior to the defibration. A method for producing the fibrous cellulose composite resin according to claim 5.

[0011] (Means described in claim 7) It is a reinforcing material for thermoplastic resins and thermosetting resins, Contains fibrous cellulose and an acid-modified resin, The fibrous cellulose includes microfibrous cellulose in which some or all of the hydroxyl groups have been substituted with carbamate groups, acid groups of the acid-modified resin ionically bond with some or all of the carbamate groups of the microfibrous cellulose; The degree of substitution of the carbamate group is 0.05 to 0.5, and the crystallinity of the microfibrous cellulose is 50 to 95%, The microfiber cellulose has an average fiber length of 0.02 to 2.0 mm and an average fiber diameter of 0.1 to 15 μm, and the proportion of fibers having a fiber length of 0.2 mm or less is 20% or more. A resin reinforcing material characterized by: [Effects of the Invention]

[0012] According to the present invention, there are provided a high-strength fibrous cellulose composite resin, a method for producing the same, and a resin reinforcing material that can significantly improve the strength of resin. DETAILED DESCRIPTION OF THE INVENTION

[0013] Next, an embodiment of the present invention will be described. Note that this embodiment is an example of the present invention, and the scope of the present invention is not limited to the scope of this embodiment.

[0014] The fibrous cellulose composite resin of this embodiment includes fibrous cellulose (hereinafter also referred to as "cellulose fiber"), a resin, and an acid-modified resin. It also includes microfiber cellulose as part or all of the fibrous cellulose. This microfiber cellulose has predetermined physical properties, and some or all of the hydroxyl groups (-OH groups) are substituted with carbamate groups. Some or all of the carbamate groups are ionically bonded to the acid groups of the acid-modified resin. To obtain this fibrous cellulose composite resin, a cellulose raw material is defibrated to form microfiber cellulose, and this microfiber cellulose is kneaded with a resin. The defibration is performed so that the microfiber cellulose has predetermined physical properties. Furthermore, some or all of the hydroxyl groups of the microfiber cellulose are modified with carbamate groups before or after defibration. An acid-modified resin is added prior to or during kneading with the resin. This process will be described in detail below.

[0015] (microfiber cellulose) In this embodiment, microfiber cellulose (microfibrillated cellulose), which is a fine fiber, is used as part or all of the fibrous cellulose. The use of microfiber cellulose significantly improves the reinforcing effect of the resin. Microfiber cellulose also has the property of being more easily modified with carbamate groups than cellulose nanofiber, which is also a fine fiber.

[0016] In this embodiment, microfibrous cellulose refers to fibers with a larger average fiber diameter than cellulose nanofibers. Specifically, it is, for example, 0.1 to 15 μm, preferably 0.2 to 10 μm. If the average fiber diameter of the microfibrous cellulose is less than 0.1 μm, it becomes no different from cellulose nanofibers, and there is a risk that the effect of improving the strength of the resin (particularly the flexural modulus) will not be sufficiently obtained. In addition, the defibration time will be longer, requiring a large amount of energy. Furthermore, the dewaterability of the cellulose fiber slurry will deteriorate. If the dewaterability deteriorates, a large amount of energy will be required for drying, and if a large amount of energy is applied to drying, the microfibrous cellulose will be thermally deteriorated, and the strength may decrease. On the other hand, if the average fiber diameter of the microfibrous cellulose exceeds 15 μm, it becomes no different from pulp, and there is a risk that the reinforcing effect will be insufficient.

[0017] Microfiber cellulose can be obtained by defibrating (refining) a cellulose raw material (hereinafter also referred to as "raw material pulp"). As the raw material pulp, one or more types can be selected from, for example, wood pulp made from hardwoods, softwoods, etc.; non-wood pulp made from straw, bagasse, cotton, hemp, bast fibers, etc.; and deionized paper pulp (DIP) made from recycled waste paper, broke, etc. Note that the above-mentioned various raw materials may be in a pulverized (powdered) state, such as cellulose powder.

[0018] However, in order to minimize the inclusion of impurities, it is preferable to use wood pulp as the raw material pulp. As the wood pulp, for example, one or more types can be selected from chemical pulps such as hardwood kraft pulp (LKP) and softwood kraft pulp (NKP), and mechanical pulp (TMP), etc.

[0019] The hardwood kraft pulp may be bleached hardwood kraft pulp, unbleached hardwood kraft pulp, or semi-bleached hardwood kraft pulp. Similarly, the softwood kraft pulp may be bleached softwood kraft pulp, unbleached softwood kraft pulp, or semi-bleached softwood kraft pulp.

[0020] As the mechanical pulp, for example, one or more types can be selected and used from stone ground pulp (SGP), pressurized stone ground pulp (PGW), refiner ground pulp (RGP), chemi-ground pulp (CGP), thermo-ground pulp (TGP), ground pulp (GP), thermo-mechanical pulp (TMP), chemi-thermomechanical pulp (CTMP), refiner mechanical pulp (RMP), bleached thermo-mechanical pulp (BTMP), etc.

[0021] The raw pulp can be pretreated by a chemical method prior to defibration. Examples of chemical pretreatments include hydrolysis of polysaccharides with acid (acid treatment), hydrolysis of polysaccharides with enzymes (enzyme treatment), swelling of polysaccharides with alkali (alkali treatment), oxidation of polysaccharides with an oxidizing agent (oxidation treatment), and reduction of polysaccharides with a reducing agent (reduction treatment). However, as a chemical pretreatment, enzyme treatment is preferred, and it is more preferred to additionally perform one or more treatments selected from acid treatment, alkali treatment, and oxidation treatment. Enzyme treatment will be described in detail below.

[0022] As the enzyme used in the enzymatic treatment, it is preferable to use at least one of cellulase enzymes and hemicellulase enzymes, and more preferably to use both in combination. The use of these enzymes makes it easier to defibrate the cellulose raw material. Note that cellulase enzymes cause the decomposition of cellulose in the presence of water. Also, hemicellulase enzymes cause the decomposition of hemicellulose in the presence of water.

[0023] Examples of cellulase enzymes that can be used include enzymes produced by species of the genera Trichoderma (filamentous fungi), Acremonium (filamentous fungi), Aspergillus (filamentous fungi), Phanerochaete (basidiomycetes), Trametes (basidiomycetes), Humicola (filamentous fungi), Bacillus (bacteria), Schizophyllum (basidiomycetes), Streptomyces (bacteria), and Pseudomonas (bacteria). These cellulase enzymes are available as reagents or commercially available products. Examples of commercially available products include Celluleucin T2 (manufactured by HPI), Meicerase (manufactured by Meiji Seika Kaisha), Novozym 188 (manufactured by Novozym), Multifect CX10L (manufactured by Genencor), and cellulase enzyme GC220 (manufactured by Genencor).

[0024] In addition, as the cellulase enzyme, either EG (endoglucanase) or CBH (cellobiohydrolase) can be used. EG and CBH can be used alone or in combination. They can also be used in combination with a hemicellulase enzyme.

[0025] Examples of hemicellulase enzymes that can be used include xylanase, which is an enzyme that breaks down xylan, mannase, which is an enzyme that breaks down mannan, and arabanase, which is an enzyme that breaks down araban. Also usable is pectinase, which is an enzyme that breaks down pectin.

[0026] Hemicellulose is a polysaccharide, excluding pectins, found between the cellulose microfibrils of plant cell walls. Hemicellulose is diverse and varies depending on the type of wood and the wall layers of the cell wall. Glucomannan is the main component in the secondary walls of softwoods, while 4-O-methylglucuronoxylan is the main component in the secondary walls of hardwoods. Therefore, when obtaining fine fibers from softwood bleached kraft pulp (NBKP), it is preferable to use mannase. Furthermore, when obtaining fine fibers from hardwood bleached kraft pulp (LBKP), it is preferable to use xylanase.

[0027] The amount of enzyme added to the cellulose raw material is determined by, for example, the type of enzyme, the type of wood used as the raw material (coniferous or broad-leaved), the type of mechanical pulp, etc. However, the amount of enzyme added to the cellulose raw material is preferably 0.1 to 3 mass%, more preferably 0.3 to 2.5 mass%, and particularly preferably 0.5 to 2 mass%. If the amount of enzyme added is less than 0.1 mass%, the effect of adding the enzyme may not be fully obtained. On the other hand, if the amount of enzyme added is more than 3 mass%, the cellulose may be saccharified, resulting in a decrease in the yield of fine fibers. Another problem is that the improvement in effect may not be commensurate with the increase in the amount added.

[0028] When a cellulase enzyme is used as the enzyme, the pH during the enzymatic treatment is preferably in the weak acidic range (pH = 3.0 to 6.9) from the viewpoint of the reactivity of the enzymatic reaction. On the other hand, when a hemicellulase enzyme is used as the enzyme, the pH during the enzymatic treatment is preferably in the weak alkaline range (pH = 7.1 to 10.0).

[0029] The temperature during the enzyme treatment is preferably 30 to 70°C, more preferably 35 to 65°C, and particularly preferably 40 to 60°C, regardless of whether a cellulase enzyme or a hemicellulase enzyme is used as the enzyme. If the temperature during the enzyme treatment is 30°C or higher, the enzyme activity is less likely to decrease, and prolonged treatment time can be prevented. On the other hand, if the temperature during the enzyme treatment is 70°C or lower, deactivation of the enzyme can be prevented.

[0030] The time for the enzyme treatment is determined depending on, for example, the type of enzyme, the temperature of the enzyme treatment, the pH during the enzyme treatment, etc. However, the time for the enzyme treatment is generally 0.5 to 24 hours.

[0031] After the enzymatic treatment, it is preferable to inactivate the enzyme. Examples of methods for inactivating the enzyme include adding an alkaline aqueous solution (preferably pH 10 or higher, more preferably pH 11 or higher) and adding hot water at 80 to 100°C.

[0032] Next, the alkali treatment method will be described. When the pulp is treated with alkali prior to defibration, some of the hydroxyl groups in the hemicellulose and cellulose in the pulp dissociate, and the molecules become anionic, weakening the intramolecular and intermolecular hydrogen bonds, which promotes the dispersion of the cellulose raw material during defibration.

[0033] Examples of the alkali used in the alkali treatment include organic alkalis such as sodium hydroxide, lithium hydroxide, potassium hydroxide, aqueous ammonia, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, and benzyltrimethylammonium hydroxide. However, from the viewpoint of production costs, it is preferable to use sodium hydroxide.

[0034] By subjecting the microfibrous cellulose to an enzyme treatment, acid treatment, or oxidation treatment prior to defibration, the water retention of the microfibrous cellulose can be reduced, the crystallinity can be increased, and the homogeneity can be improved. In this regard, when the water retention of the microfibrous cellulose is low, it becomes easier to dehydrate, and the dewatering property of the cellulose fiber slurry is improved.

[0035] When raw pulp is treated with enzymes, acids, or oxidation, the hemicellulose and amorphous regions of cellulose contained in the pulp are decomposed. As a result, the energy required for defibration can be reduced, and the uniformity and dispersibility of the cellulose fibers can be improved. However, because pretreatment reduces the aspect ratio of microfiber cellulose, excessive pretreatment is preferably avoided when using it as a reinforcing material for resins.

[0036] The raw material pulp can be defibrated by beating the raw material pulp using, for example, a homogenizer such as a beater, a high-pressure homogenizer, or a high-pressure homogenizer, a grinder, a millstone-type friction machine such as a grinder, a single-screw kneader, a multi-screw kneader, a kneader refiner, a jet mill, etc. However, it is preferable to use a refiner or a jet mill.

[0037] The average fiber length (average length of single fibers) of the microfiber cellulose is preferably 0.02 to 2.0 mm, more preferably 0.05 to 1.5 mm, and particularly preferably 0.1 to 1.0 mm. If the average fiber length is less than 0.02 mm, a three-dimensional network cannot be formed between the fibers, which may reduce the reinforcing effect of the resin. On the other hand, if the average fiber length exceeds 2.0 mm, the reinforcing effect may be insufficient because the length is the same as that of the raw material pulp.

[0038] The average fiber length of the microfiber cellulose can be adjusted as desired by, for example, selecting the raw material pulp, pre-treating it, defibrating it, and the like.

[0039] The proportion of microfiber cellulose fibers with a length of 0.2 mm or less is preferably 20% or more, more preferably 40% or more, and particularly preferably 60% or more. If this proportion is less than 20%, the reinforcing effect of the resin may not be sufficiently obtained. On the other hand, there is no upper limit to the proportion of microfiber cellulose fibers with a length of 0.2 mm or less, and all fibers may be 0.2 mm or less.

[0040] The aspect ratio of the microfibrous cellulose is preferably 2 to 15,000, more preferably 10 to 10,000. If the aspect ratio is less than 2, a three-dimensional network cannot be constructed, which may result in insufficient reinforcing effect. On the other hand, if the aspect ratio is more than 15,000, the microfibrous cellulose may become highly entangled with itself, resulting in insufficient dispersion in the resin.

[0041] The fibrillation rate of the microfibrous cellulose is preferably 1.0 to 30.0%, more preferably 1.5 to 20.0%, and particularly preferably 2.0 to 15.0%. If the fibrillation rate exceeds 30.0%, the contact area with water becomes too large, which may make dehydration difficult even if the cellulose is defibrated to an average fiber width of 0.1 μm or more. On the other hand, if the fibrillation rate is less than 1.0%, there may be few hydrogen bonds between fibrils, making it impossible to form a strong three-dimensional network.

[0042] The crystallinity of the microfibrous cellulose is preferably 50% or more, more preferably 55% or more, and particularly preferably 60% or more. If the crystallinity is below 50%, although the mixability with pulp and cellulose nanofibers is improved, the strength of the fiber itself is reduced, which may make it impossible to improve the strength of the resin. On the other hand, the crystallinity of the microfibrous cellulose is preferably 95% or less, more preferably 90% or less, and particularly preferably 85% or less. If the crystallinity is above 95%, the proportion of strong hydrogen bonds within the molecule increases, the fiber itself becomes rigid, and dispersibility deteriorates.

[0043] The crystallinity of the microfiber cellulose can be adjusted as desired by, for example, selecting the raw material pulp, pre-treating it, and pulverizing it.

[0044] The pulp viscosity of the microfibrous cellulose is preferably 2 cps or more, more preferably 4 cps or more. If the pulp viscosity of the microfibrous cellulose is less than 2 cps, it may be difficult to suppress the aggregation of the microfibrous cellulose.

[0045] The freeness of the microfibrous cellulose is preferably 500 ml or less, more preferably 300 ml or less, and particularly preferably 100 ml or less. If the freeness of the microfibrous cellulose exceeds 500 ml, the average fiber diameter of the microfibrous cellulose will exceed 10 μm, and the strength improving effect of the resin may not be sufficiently obtained.

[0046] The zeta potential of the microfibrous cellulose is preferably -150 to 20 mV, more preferably -100 to 0 mV, and particularly preferably -80 to -10 mV. If the zeta potential is below -150 mV, compatibility with the resin may be significantly reduced, resulting in insufficient reinforcing effect. On the other hand, if the zeta potential is above 20 mV, dispersion stability may be reduced.

[0047] The water retention of the microfibrous cellulose is preferably 80 to 400%, more preferably 90 to 350%, and particularly preferably 100 to 300%. If the water retention is below 80%, the reinforcing effect may be insufficient because it is no different from the raw material pulp. On the other hand, if the water retention is above 400%, the dewatering ability tends to be poor and the microfibrous cellulose is prone to aggregation. In this regard, the water retention of the microfibrous cellulose can be further reduced by substituting the hydroxyl groups of the fibers with carbamate groups, thereby improving the dewatering ability and drying ability.

[0048] The water retention of the microfiber cellulose can be adjusted as desired by, for example, selecting the raw material pulp, pre-treating it, defibrating it, and the like.

[0049] The content of microfibrous cellulose in the cellulose fibers is preferably 60 to 100% by mass, more preferably 70 to 99% by mass, and particularly preferably 80 to 98% by mass. If the content of microfibrous cellulose is less than 60% by mass, a sufficient reinforcing effect may not be obtained. Furthermore, if the content of microfibrous cellulose is less than 60% by mass, the content of pulp and cellulose nanofibers will increase relatively, and the effect of containing microfibrous cellulose may not be obtained.

[0050] The microfibrous cellulose is provided with a carbamate group, for example, by the method described below. That is, a carbamate (an ester of carbamic acid) is introduced into the microfibrous cellulose. The carbamate group is a group represented by -O-CO-NH-, such as -O-CO-NH2, -O-CONHR, or -O-CO-NR2. That is, the carbamate group can be represented by the following structural formula (1).

[0051] [ka]

[0052] Here, each R is independently at least one of a saturated linear hydrocarbon group, a saturated branched hydrocarbon group, a saturated cyclic hydrocarbon group, an unsaturated linear hydrocarbon group, an unsaturated branched hydrocarbon group, an aromatic group, and a derivative group thereof.

[0053] Examples of saturated linear hydrocarbon groups include linear alkyl groups having 1 to 10 carbon atoms, such as methyl, ethyl, and propyl groups.

[0054] Examples of the saturated branched hydrocarbon group include branched alkyl groups having 3 to 10 carbon atoms, such as an isopropyl group, a sec-butyl group, an isobutyl group, and a tert-butyl group.

[0055] Examples of saturated cyclic hydrocarbon groups include cycloalkyl groups such as cyclopentyl, cyclohexyl, and norbornyl.

[0056] Examples of the unsaturated linear hydrocarbon group include linear alkenyl groups having 2 to 10 carbon atoms, such as ethenyl, propen-1-yl, and propen-3-yl, and linear alkynyl groups having 2 to 10 carbon atoms, such as ethynyl, propyn-1-yl, and propyn-3-yl.

[0057] Examples of the unsaturated branched hydrocarbon group include branched alkenyl groups having 3 to 10 carbon atoms, such as a propen-2-yl group, a buten-2-yl group, and a buten-3-yl group, and branched alkynyl groups having 4 to 10 carbon atoms, such as a butyn-3-yl group.

[0058] Examples of the aromatic group include a phenyl group, a tolyl group, a xylyl group, and a naphthyl group.

[0059] Examples of the derivative group include groups in which one or more hydrogen atoms of the above-mentioned saturated linear hydrocarbon group, saturated branched hydrocarbon group, saturated cyclic hydrocarbon group, unsaturated linear hydrocarbon group, unsaturated branched hydrocarbon group, and aromatic group have been substituted with a substituent (for example, a hydroxy group, a carboxy group, a halogen atom, etc.).

[0060] In microfibrous cellulose having carbamate groups (carbamate introduced), some or all of the highly polar hydroxyl groups are substituted with relatively less polar carbamate groups. Therefore, the microfibrous cellulose has low hydrophilicity and high affinity with low-polarity resins, etc. As a result, the microfibrous cellulose has excellent uniform dispersibility in resins. In addition, the slurry of the microfibrous cellulose has low viscosity and is easy to handle.

[0061] The lower limit of the degree of substitution of carbamate groups for hydroxy groups in microfibrous cellulose is preferably 0.05, more preferably 0.1, and particularly preferably 0.2. When the degree of substitution is 0.05 or more, the effect of introducing carbamate is reliably achieved. On the other hand, the upper limit of the degree of substitution is preferably 1, more preferably 0.5, and particularly preferably 0.4. In this respect, microfibrous cellulose with a high degree of substitution has the problem of being expensive.

[0062] Cellulose is a polymer with anhydroglucose as a structural unit, and each structural unit has three hydroxyl groups. Therefore, if all the hydroxyl groups are substituted with carbamate groups, the degree of substitution is 3.

[0063] <Carbamate formation> Regarding the introduction of carbamate (carbamation) into microfiber cellulose (or the cellulose raw material if carbamate conversion is performed before defibration), there are two methods: one is to carbamate the cellulose raw material and then pulverize it, and the other is to pulverize the cellulose raw material and then carbamate it. In this specification, defibration of the cellulose raw material is explained first, and then carbamate conversion (modification). However, either defibration or carbamate conversion can be performed first. However, it is preferable to perform carbamate conversion first, and then defibration. This is because the cellulose raw material before defibration has high dehydration efficiency, and the heating associated with carbamate conversion puts the cellulose raw material in a state that is easy to defibrate.

[0064] The process of carbamate-forming microfibrous cellulose can be mainly divided into, for example, a mixing process, a removing process, and a heating process. The mixing process and the removing process can also be collectively referred to as a preparation process for preparing a mixture to be subjected to the heating process.

[0065] In the mixing step, microfibrous cellulose and urea or a derivative of urea (hereinafter also simply referred to as "urea, etc.") are mixed in a dispersion medium.

[0066] Examples of urea and urea derivatives that can be used include urea, thiourea, biuret, phenylurea, benzylurea, dimethylurea, diethylurea, tetramethylurea, and compounds in which the hydrogen atoms of urea are substituted with alkyl groups. These ureas and urea derivatives can be used alone or in combination. However, it is preferable to use urea.

[0067] The lower limit of the mixing mass ratio of urea etc. to the cellulose raw material etc. (urea etc. / cellulose raw material) is preferably 10 / 100, more preferably 20 / 100. On the other hand, the upper limit is preferably 300 / 100, more preferably 200 / 100. By making the mixing mass ratio 10 / 100 or more, the efficiency of carbamate formation is improved. On the other hand, even if the mixing mass ratio exceeds 300 / 100, the carbamate formation reaches a plateau.

[0068] The dispersion medium is usually water, although other dispersion media such as alcohols and ethers, or mixtures of water with other dispersion media may also be used.

[0069] In the mixing step, for example, microfibrous cellulose and urea or the like may be added to water, microfibrous cellulose may be added to an aqueous solution of urea or the like, or urea or the like may be added to a slurry containing microfibrous cellulose. Furthermore, stirring may be performed after addition to achieve uniform mixing. Furthermore, the dispersion containing microfibrous cellulose and urea or the like may contain other components.

[0070] In the removing step, the dispersion medium is removed from the dispersion liquid containing the microfibrous cellulose and urea, etc. obtained in the mixing step. By removing the dispersion medium, the urea, etc. can be reacted efficiently in the subsequent heating step.

[0071] The dispersion medium is preferably removed by volatilizing it by heating, which allows efficient removal of the dispersion medium while leaving behind components such as urea.

[0072] When the dispersion medium is water, the lower limit of the heating temperature in the removal step is preferably 50°C, more preferably 70°C, and particularly preferably 90°C. By setting the heating temperature to 50°C or higher, the dispersion medium can be efficiently volatilized (removed). On the other hand, the upper limit of the heating temperature is preferably 120°C, more preferably 100°C. If the heating temperature exceeds 120°C, the dispersion medium and urea may react, resulting in the urea decomposing independently.

[0073] The heating time in the removal step can be adjusted appropriately depending on the solid content concentration of the dispersion, etc. Specifically, it is, for example, 6 to 24 hours.

[0074] In the heating step following the removal step, a mixture of microfibrous cellulose and urea or the like is heat-treated. In this heating step, some or all of the hydroxyl groups of the microfibrous cellulose react with urea or the like and are replaced with carbamate groups. More specifically, when urea or the like is heated, it is decomposed into isocyanic acid and ammonia as shown in the following reaction formula (1). Isocyanic acid is highly reactive and, for example, modifies the hydroxyl groups of cellulose into carbamate groups as shown in the following reaction formula (2). NH2-CO-NH2→ HN=C=O + NH3…(1) Cell-OH + HN=C=O → Cell-O-CO-NH2…(2) The lower limit of the heating temperature in the heating step is preferably 120°C, more preferably 130°C, particularly preferably above the melting point of urea (about 134°C), even more preferably 140°C, and most preferably 150°C. By setting the heating temperature to 120°C or higher, carbamate formation is carried out efficiently. The upper limit of the heating temperature is preferably 200°C, more preferably 180°C, and particularly preferably 170°C. If the heating temperature exceeds 200°C, the microfibrous cellulose may decompose, resulting in insufficient reinforcing effect.

[0075] The lower limit of the heating time in the heating step is preferably 1 minute, more preferably 5 minutes, particularly preferably 30 minutes, even more preferably 1 hour, and most preferably 2 hours. By setting the heating time to 1 minute or more, the carbamate reaction can be carried out reliably. On the other hand, the upper limit of the heating time is preferably 15 hours, more preferably 10 hours. A heating time of more than 15 hours is not economical, and carbamate formation can be carried out sufficiently in 15 hours.

[0076] The above heat treatment is preferably carried out under acidic conditions. Carbamate formation proceeds more reliably by carrying out the heat treatment under acidic conditions. The upper limit of the pH of the mixture in the heating step is preferably 6, more preferably 5, and particularly preferably 4. On the other hand, the lower limit of the pH is preferably 1, more preferably 2, and particularly preferably 3. The pH can be adjusted by adding an acidic compound (e.g., acetic acid, citric acid, etc.) or an alkaline compound (e.g., sodium hydroxide, calcium hydroxide, etc.) to the mixture.

[0077] As the heating device in the heating step, for example, a hot air dryer, a paper machine, a dry pulp machine, etc. can be used.

[0078] The mixture after the heat treatment may be washed. This washing may be carried out with water or the like. By this washing, unreacted urea and the like remaining can be removed.

[0079] (Cellulose nanofiber) In this embodiment, the fibrous cellulose may contain cellulose nanofibers together with microfiber cellulose. Cellulose nanofibers are fine fibers like microfiber cellulose, and play a role in complementing microfiber cellulose in improving the strength of the resin. However, if possible, it is preferable to use only microfiber cellulose as the fine fibers without including cellulose nanofibers. However, if cellulose nanofibers are to be included, the following cellulose nanofibers are recommended.

[0080] First, cellulose nanofibers can be obtained by defibrating (refining) raw pulp (cellulose raw material). The raw pulp can be the same as that used for microfiber cellulose, and it is preferable to use the same as that used for microfiber cellulose.

[0081] The raw pulp for cellulose nanofibers can be pretreated and defibrated in the same way as for microfiber cellulose. However, the degree of defibration differs; for example, it must be performed so that the average fiber diameter is less than 0.1 μm. Below, we will mainly explain the differences from microfiber cellulose.

[0082] The average fiber diameter (average fiber width; average diameter of a single fiber) of cellulose nanofibers is preferably 4 to 100 nm, more preferably 10 to 80 nm. If the average fiber diameter of cellulose nanofibers is less than 4 nm, dehydration may deteriorate. Furthermore, in this embodiment in which cellulose nanofibers are mixed with a dispersant, the dispersant may not sufficiently cover (stick to) the cellulose nanofibers, and dispersibility may not be sufficiently improved. On the other hand, if the average fiber diameter of cellulose nanofibers exceeds 100 nm, they can no longer be called cellulose nanofibers.

[0083] The average fiber diameter of cellulose nanofibers can be adjusted, for example, by selecting raw material pulp, pre-treating, defibrating, etc.

[0084] The average fiber length (single fiber length) of the cellulose nanofibers is preferably 0.1 to 1,000 μm, more preferably 0.5 to 500 μm. If the average fiber length of the cellulose nanofibers is less than 0.1 μm, a three-dimensional network cannot be formed between the cellulose nanofibers, and the reinforcing effect may be insufficient. On the other hand, if the average fiber length of the cellulose nanofibers is more than 1,000 μm, the fibers may easily become entangled, and dispersibility may not be sufficiently improved.

[0085] The average fiber length of the cellulose nanofibers can be adjusted, for example, by selecting the raw material pulp, pre-treating it, defibrating it, etc.

[0086] The water retention of cellulose nanofibers can be adjusted, for example, by selecting the raw material pulp, pre-treating it, defibrating it, etc.

[0087] The crystallinity of the cellulose nanofiber is preferably 95 to 50%, more preferably 90 to 60%. If the crystallinity of the cellulose nanofiber is within the above range, the strength of the resin can be reliably improved.

[0088] The crystallinity can be adjusted as desired by, for example, selecting the raw pulp, pre-treating it, defibrating it, and the like.

[0089] The pulp viscosity of the cellulose nanofiber is preferably 1.0 cps or more, more preferably 2.0 cps or more. Pulp viscosity is the viscosity of the solution obtained after dissolving cellulose in a copper ethylenediamine solution, and a higher pulp viscosity indicates a higher degree of polymerization of cellulose. A pulp viscosity of 1.0 cps or more can impart dewaterability to the slurry while suppressing decomposition of the cellulose nanofiber when kneaded with a resin, thereby achieving a sufficient reinforcing effect.

[0090] If necessary, the cellulose nanofibers obtained by defibration can be dispersed in an aqueous medium to form a dispersion before mixing with other cellulose fibers. It is particularly preferable that the aqueous medium is entirely water (aqueous solution). However, the aqueous medium may also contain other liquids, some of which are compatible with water. Examples of other liquids that can be used include lower alcohols with 3 or fewer carbon atoms.

[0091] The Brookfield viscosity of the cellulose nanofiber dispersion (1% concentration) is preferably 10 to 2,000 cp, and more preferably 30 to 1,500 cp. If the Brookfield viscosity of the dispersion is within this range, it becomes easier to mix with other cellulose fibers and the dewatering properties of the cellulose fiber slurry are improved.

[0092] The content of cellulose nanofibers in the cellulose fibers is preferably 40% by mass or less, more preferably 20% by mass or less. If the cellulose nanofiber content exceeds 40% by mass, the cellulose nanofibers may aggregate strongly and may not be dispersed in the resin, resulting in insufficient reinforcing effect. As mentioned above, it is most preferable to not include cellulose nanofibers, that is, to have a content of 0% by mass.

[0093] If necessary, the cellulose nanofibers can be carbamate-converted by the same method as for the microfibrous cellulose, although carbamate-converting cellulose nanofibers is usually difficult.

[0094] (pulp) In addition to microfiber cellulose, the fibrous cellulose can contain pulp. Pulp plays a role in significantly improving the dewatering properties of the cellulose fiber slurry. However, it is preferable that the pulp content be within a specified range (see below).

[0095] The pulp content in the cellulose fiber is preferably 40% by mass or less, more preferably 20% by mass or less. If the pulp content exceeds 40% by mass, the microfiber cellulose content will decrease, which may result in a loss of resin strength. As with cellulose nanofibers, it is most preferable to not include pulp, i.e., to have a content of 0% by mass.

[0096] The pulp may be the same as the raw pulp for microfiber cellulose, etc., and is preferably the same as the raw pulp for microfiber cellulose. Using the same pulp as the raw pulp for microfiber cellulose improves the affinity of the cellulose fibers, resulting in improved homogeneity of the cellulose fiber slurry.

[0097] (slurry) If necessary, the fibrous cellulose containing fine fibers is dispersed in an aqueous medium to form a dispersion (slurry). It is particularly preferable that the aqueous medium is entirely water, but an aqueous medium containing a part of another liquid that is compatible with water can also be used. Examples of the other liquid include lower alcohols having 3 or less carbon atoms.

[0098] The solid content of the slurry is preferably 0.1 to 10.0% by mass, more preferably 0.5 to 5.0% by mass. If the solid content is less than 0.1% by mass, excessive energy may be required for dehydration and drying. On the other hand, if the solid content is more than 10.0% by mass, the fluidity of the slurry itself may decrease, making it difficult to uniformly mix the dispersant.

[0099] (acid-modified resin) In the acid-modified resin, the acid groups are ionic bonded to some or all of the carbamate groups, and this ionic bond improves the reinforcing effect of the resin.

[0100] Examples of acid-modified resins that can be used include acid-modified polyolefin resins, acid-modified epoxy resins, and acid-modified styrene-based elastomer resins. However, it is preferable to use acid-modified polyolefin resins. Acid-modified polyolefin resins are copolymers of unsaturated carboxylic acid components and polyolefin components.

[0101] As the polyolefin component, for example, one or more types can be selected from polymers of alkenes such as ethylene, propylene, butadiene, isoprene, etc. However, it is preferable to use a polypropylene resin, which is a polymer of propylene.

[0102] As the unsaturated carboxylic acid component, for example, one or more selected from maleic anhydrides, phthalic anhydrides, itaconic anhydrides, citraconic anhydrides, citric anhydrides, etc. can be used. However, it is preferable to use maleic anhydrides. In other words, it is preferable to use maleic anhydride-modified polypropylene resin.

[0103] The amount of acid-modified resin mixed is preferably 0.1 to 1,000 parts by mass, more preferably 1 to 500 parts by mass, and particularly preferably 10 to 200 parts by mass, per 100 parts by mass of microfiber cellulose. In particular, when the acid-modified resin is a maleic anhydride-modified polypropylene resin, the amount is preferably 1 to 200 parts by mass, more preferably 10 to 100 parts by mass. If the amount of acid-modified resin mixed is less than 0.1 part by mass, the improvement in strength is insufficient. On the other hand, if the amount mixed is more than 1,000 parts by mass, the amount becomes excessive and the strength tends to decrease.

[0104] The weight average molecular weight of the maleic anhydride modified polypropylene is, for example, 1,000 to 100,000, and preferably 3,000 to 50,000.

[0105] The acid value of the maleic anhydride-modified polypropylene is preferably 0.5 mgKOH / g or more and 100 mgKOH / g or less, and more preferably 1 mgKOH / g or more and 50 mgKOH / g or less.

[0106] (dispersant) Fibrous cellulose, including microfibrous cellulose, is more preferably mixed with a dispersant, which is preferably an aromatic compound having an amine group and / or a hydroxyl group, or an aliphatic compound having an amine group and / or a hydroxyl group.

[0107] Examples of compounds having an amine group and / or a hydroxyl group in an aromatic group include anilines, toluidines, trimethylanilines, anisidines, tyramines, histamines, tryptamines, phenols, dibutylhydroxytoluenes, bisphenol A, cresols, eugenols, gallic acids, guaiacols, picric acids, phenolphthalein, serotonins, dopamines, adrenalines, noradrenalines, thymols, tyrosines, salicylic acids, methyl salicylates, and azathioprine. Examples include varnish alcohols, salicylic alcohols, sinapyl alcohols, diphenidol, diphenylmethanols, cinnamyl alcohols, scopolamines, tryptophols, vanillyl alcohols, 3-phenyl-1-propanols, phenethyl alcohols, phenoxyethanols, veratryl alcohols, benzyl alcohols, benzoins, mandelic acids, mandelonitriles, benzoic acids, phthalic acids, isophthalic acids, terephthalic acids, mellitic acids, and cinnamic acids.

[0108] Furthermore, examples of compounds having an amine group and / or a hydroxyl group in an aliphatic group include capryl alcohols, 2-ethylhexanols, pelargonic alcohols, capric alcohols, undecyl alcohols, lauryl alcohols, tridecyl alcohols, myristyl alcohols, pentadecyl alcohols, cetanols, stearyl alcohols, elaidyl alcohols, oleyl alcohols, linoleyl alcohols, methylamines, dimethylamines, trimethylamines, ethylamines, diethylamines, and ethylenediamines. , triethanolamines, N,N-diisopropylethylamines, tetramethylethylenediamines, hexamethylenediamines, spermidines, spermines, amantadine, formic acids, acetic acids, propionic acids, butyric acids, valeric acids, caproic acids, enanthic acids, caprylic acids, pelargonic acids, capric acids, lauric acids, myristic acids, palmitic acids, margaric acids, stearic acids, oleic acids, linoleic acids, linolenic acids, arachidonic acids, eicosapentaenoic acids, docosahexaenoic acids, and sorbic acids.

[0109] The above dispersants inhibit hydrogen bonding between microfibrous cellulose molecules. Therefore, when the microfibrous cellulose and resin are kneaded, the microfibrous cellulose is reliably dispersed (redispersed) in the resin. The above dispersants also serve to improve the compatibility between the microfibrous cellulose and the resin. In this respect, the dispersibility of the microfibrous cellulose in the resin is improved.

[0110] It is possible to add a compatibilizing agent (chemical) separately when kneading the fibrous cellulose and resin, but mixing the fibrous cellulose and dispersing agent (chemical) in advance rather than adding the chemical at this stage will result in the chemical sticking more uniformly to the fibrous cellulose and will be more effective in improving compatibility with the resin.

[0111] For example, polypropylene has a melting point of 160°C, so the fibrous cellulose and resin are mixed at approximately 180°C. However, if a dispersant (liquid) is added in this state, it will dry out instantly. Therefore, there is a method in which a masterbatch (a composite resin with a high concentration of microfiber cellulose) is prepared using a resin with a low melting point, and then the concentration is reduced with a normal resin. However, resins with low melting points generally have low strength. Therefore, this method may result in a decrease in the strength of the composite resin.

[0112] The amount of dispersant mixed is preferably 0.1 to 1,000 parts by mass, more preferably 1 to 500 parts by mass, and particularly preferably 10 to 200 parts by mass, relative to 100 parts by mass of microfiber cellulose. If the amount of dispersant mixed is less than 0.1 part by mass, the improvement in strength may be insufficient. On the other hand, if the amount mixed is more than 1,000 parts by mass, the amount becomes excessive and the strength tends to decrease.

[0113] In this regard, the acid-modified resin described above improves compatibility and enhances reinforcing effects by forming ionic bonds between the acid groups and the carbamate groups of the microfibrous cellulose, and its large molecular weight makes it compatible with the resin, which is thought to contribute to improving strength. On the other hand, the dispersant described above intervenes between the hydroxyl groups of the microfibrous cellulose to prevent aggregation, thereby improving dispersibility in the resin. Furthermore, because its molecular weight is smaller than that of the acid-modified resin, it can enter the narrow spaces between the microfibrous cellulose that the acid-modified resin cannot enter, improving dispersibility and improving strength. From the above perspective, the molecular weight of the acid-modified resin is preferably 2 to 2,000 times, preferably 5 to 1,000 times, the molecular weight of the dispersant.

[0114] To explain this point in more detail, resin powder physically intervenes between microfibrous cellulose particles, inhibiting hydrogen bonding and thereby improving the dispersibility of the microfibrous cellulose. In contrast, acid-modified resins form ionic bonds between acid groups and carbamate groups of microfibrous cellulose, improving compatibility and thereby enhancing reinforcing effects. While dispersants inhibit hydrogen bonding between microfibrous cellulose particles, resin powders, being on the micron order, physically intervene and inhibit hydrogen bonding. Therefore, although dispersibility is lower than that of dispersants, the resin powder itself melts and forms a matrix, so it does not contribute to a decrease in physical properties. On the other hand, dispersants are at the molecular level and are extremely small, so they cover the microfibrous cellulose, inhibiting hydrogen bonding and effectively improving the dispersibility of microfibrous cellulose. However, they may remain in the resin and contribute to a decrease in physical properties.

[0115] (Manufacturing method) A mixture of fibrous cellulose, an acid-modified resin, a dispersant, etc. can be dried and pulverized to form a powder prior to kneading with the resin. This form eliminates the need to dry the fibrous cellulose when kneading with the resin, resulting in good thermal efficiency. Furthermore, if a dispersant is mixed into the mixture, there is little risk that fine fibers such as microfibrous cellulose will not redisperse even if the mixture is dried.

[0116] The mixture may be dehydrated prior to drying, if necessary, using one or more dehydration devices selected from the group consisting of a belt press, a screw press, a filter press, a twin roll, a twin wire former, a valveless filter, a center disc filter, a membrane treatment device, and a centrifuge.

[0117] The mixture can be dried using one or more selected from, for example, rotary kiln drying, disk drying, airflow drying, media fluidized drying, spray drying, drum drying, screw conveyor drying, paddle drying, uniaxial kneading drying, multiaxial kneading drying, vacuum drying, stirring drying, and the like.

[0118] The dried mixture (dried product) is pulverized to form a powder. The pulverization of the dried product can be carried out using one or more mills selected from a bead mill, kneader, disper, twist mill, cut mill, hammer mill, etc.

[0119] The average particle size of the powdery material is preferably 1 to 10,000 μm, more preferably 10 to 5,000 μm, and particularly preferably 100 to 1,000 μm. If the average particle size of the powdery material exceeds 10,000 μm, it may be difficult to knead with resin. On the other hand, reducing the average particle size of the powdery material to less than 1 μm requires a large amount of energy, which is not economical.

[0120] The average particle size of the powdery material can be controlled by controlling the degree of pulverization, as well as by classification using a classifying device such as a filter or cyclone.

[0121] The bulk density of the mixture (powder) is preferably 0.03 to 1.0, more preferably 0.04 to 0.9, and particularly preferably 0.05 to 0.8. A bulk density of more than 1.0 means that the hydrogen bonds between the fibrous cellulose are stronger, making it difficult to disperse in the resin. On the other hand, a bulk density of less than 0.03 is disadvantageous in terms of transportation costs.

[0122] The bulk specific gravity is a value measured in accordance with JIS K7365.

[0123] The moisture content of the mixture (powder) is preferably 50% or less, more preferably 30% or less, and particularly preferably 10% or less. If the moisture content exceeds 50%, the energy required for kneading with the resin becomes enormous, which is not economical.

[0124] The moisture content was calculated using the following formula, where the sample was kept at 105°C for 6 hours or more using a constant temperature dryer, and the mass at which no change in mass was observed was taken as the mass after drying. Fiber moisture content (%) = [(mass before drying - mass after drying) ÷ mass before drying] x 100

[0125] The dehydrated and dried microfiber cellulose may contain resin. If resin is included, it will inhibit hydrogen bonding between the dehydrated and dried microfiber cellulose, improving its dispersibility in the resin during kneading.

[0126] The resin contained in the dehydrated and dried microfiber cellulose may be in the form of, for example, powder, pellets, sheet, etc. However, powder (powdered resin) is preferred.

[0127] When powdered, the average particle size of the resin powder contained in the dehydrated and dried microfiber cellulose is preferably 1 to 10,000 μm, more preferably 10 to 5,000 μm, and particularly preferably 100 to 1,000 μm. If the average particle size exceeds 10,000 μm, the particles may be too large to enter a kneading device. On the other hand, if the average particle size is less than 1 μm, the particles may be too fine to inhibit hydrogen bonding between the microfiber cellulose particles. The resin, such as the powdered resin, used here may be the same or different from the resin (the resin used as the main raw material) to be kneaded with the microfiber cellulose, but it is preferable that they are the same type.

[0128] Resin powder with an average particle size of 1 to 10,000 μm is preferably mixed in an aqueous dispersion state before dehydration and drying. By mixing in an aqueous dispersion state, the resin powder can be uniformly dispersed among the microfiber cellulose, and the microfiber cellulose can be uniformly dispersed in the composite resin after kneading, further improving strength properties.

[0129] The powdery material (resin reinforcing material) obtained as described above is kneaded with resin to obtain a fibrous cellulose composite resin. This kneading can be performed, for example, by mixing the powdery material with pellet-shaped resin, or by first melting the resin and then adding the powdery material to the melt. Acid-modified resins, dispersants, etc. can also be added at this stage.

[0130] For the kneading treatment, for example, one or more types can be selected and used from a single-screw or multi-screw kneader with two or more screws, a mixing roll, a kneader, a roll mill, a Banbury mixer, a screw press, a disperser, etc. Among these, it is preferable to use a multi-screw kneader with two or more screws. Two or more multi-screw kneaders with two or more screws may be used in parallel or in series.

[0131] The peripheral speed of the screws of the twin or more multi-screw kneader is preferably 0.2 to 200 m / min, more preferably 0.5 to 150 m / min, and particularly preferably 1 to 100 m / min. If the peripheral speed is less than 0.2 m / min, the microfibrous cellulose may not be dispersed well in the resin. On the other hand, if the peripheral speed exceeds 200 m / min, the shear force on the microfibrous cellulose may be excessive, and the reinforcing effect may not be obtained.

[0132] The ratio of the screw diameter to the length of the kneading section of the kneader used in this embodiment is preferably 15 to 60. If the ratio is less than 15, the kneading section may be too short and the microfiber cellulose and the resin may not be mixed. On the other hand, if the ratio exceeds 60, the kneading section may be too long, which increases the shear load on the microfiber cellulose and may prevent the reinforcing effect from being obtained.

[0133] The kneading temperature is equal to or higher than the glass transition point of the resin, and varies depending on the type of resin, but is preferably 80 to 280°C, more preferably 90 to 260°C, and particularly preferably 100 to 240°C.

[0134] As the resin, at least one of a thermoplastic resin and a thermosetting resin can be used.

[0135] As the thermoplastic resin, one or more selected from polyolefins such as polypropylene (PP) and polyethylene (PE), polyester resins such as aliphatic polyester resins and aromatic polyester resins, polyacrylic resins such as polystyrene, methacrylate, and acrylate, polyamide resins, polycarbonate resins, polyacetal resins, etc. can be used.

[0136] However, it is preferable to use at least one of polyolefin and polyester resin. Furthermore, it is preferable to use polypropylene as the polyolefin. Furthermore, as the polyester resin, examples of aliphatic polyester resins include polylactic acid and polycaprolactone, and examples of aromatic polyester resins include polyethylene terephthalate, but it is preferable to use a biodegradable polyester resin (also simply referred to as a "biodegradable resin").

[0137] As the biodegradable resin, for example, one or more selected from hydroxycarboxylic acid-based aliphatic polyesters, caprolactone-based aliphatic polyesters, dibasic acid polyesters, and the like can be used.

[0138] The hydroxycarboxylic acid-based aliphatic polyester can be one or more selected from homopolymers of hydroxycarboxylic acids such as lactic acid, malic acid, glucose acid, 3-hydroxybutyric acid, etc., and copolymers using at least one of these hydroxycarboxylic acids. However, it is preferable to use polylactic acid, copolymers of lactic acid and the above hydroxycarboxylic acids other than lactic acid, polycaprolactone, and copolymers of caprolactone with at least one of the above hydroxycarboxylic acids, and it is particularly preferable to use polylactic acid.

[0139] As the lactic acid, for example, L-lactic acid, D-lactic acid, etc. can be used, and these lactic acids may be used alone or in combination of two or more.

[0140] As the caprolactone-based aliphatic polyester, for example, one or more types can be selected from homopolymers of polycaprolactone and copolymers of polycaprolactone or the like with the above-mentioned hydroxycarboxylic acids and the like.

[0141] As the dibasic acid polyester, for example, one or more selected from polybutylene succinate, polyethylene succinate, polybutylene adipate, etc. can be used.

[0142] The biodegradable resins may be used alone or in combination of two or more.

[0143] Examples of thermosetting resins that can be used include phenolic resins, urea resins, melamine resins, furan resins, unsaturated polyesters, diallyl phthalate resins, vinyl ester resins, epoxy resins, urethane resins, silicone resins, thermosetting polyimide resins, etc. These resins can be used alone or in combination of two or more.

[0144] The resin may contain an inorganic filler, preferably in a proportion that does not interfere with thermal recycling.

[0145] Examples of inorganic fillers include simple substances, oxides, hydroxides, carbonates, sulfates, silicates, sulfites of metal elements in Groups I to VIII of the periodic table, such as Fe, Na, K, Cu, Mg, Ca, Zn, Ba, Al, Ti, and silicon, as well as various clay minerals composed of these compounds.

[0146] Specific examples include barium sulfate, calcium sulfate, magnesium sulfate, sodium sulfate, calcium sulfite, zinc oxide, silica, heavy calcium carbonate, light calcium carbonate, aluminum borate, alumina, iron oxide, calcium titanate, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, sodium hydroxide, magnesium carbonate, calcium silicate, clay wollastonite, glass beads, glass powder, silica sand, silica stone, quartz powder, diatomaceous earth, white carbon, and glass fiber. A plurality of these inorganic fillers may be contained. Also, those contained in recycled paper pulp may be used.

[0147] The blending ratio of fibrous cellulose and resin is preferably 1 part by mass or more of fibrous cellulose and 99 parts by mass or less of resin, more preferably 2 parts by mass or more of fibrous cellulose and 98 parts by mass or less of resin, and particularly preferably 3 parts by mass or more of fibrous cellulose and 97 parts by mass or less of resin. Also, preferably 50 parts by mass or less of fibrous cellulose and 50 parts by mass or more of resin, more preferably 40 parts by mass or less of fibrous cellulose and 60 parts by mass or more of resin, and particularly preferably 30 parts by mass or less of fibrous cellulose and 70 parts by mass or more of resin. In particular, when the fibrous cellulose is 10 to 50 parts by mass, the strength of the resin composition, particularly the bending strength and tensile modulus, can be significantly improved.

[0148] The content ratio of the fibrous cellulose and the resin in the final resin composition is usually the same as the above-mentioned blending ratio of the fibrous cellulose and the resin.

[0149] Solubility parameters (cal / cm) of microfiber cellulose and resin 3 ) 1 / 2(SP value), that is, the SP of microfiber cellulose MFC Value, resin SP POL value, the difference in SP value = SP MFC Value − SP POL The difference in SP value is preferably 10 to 0.1, more preferably 8 to 0.5, and particularly preferably 5 to 1. If the difference in SP value exceeds 10, the microfibrous cellulose does not disperse in the resin, and the reinforcing effect cannot be obtained. On the other hand, if the difference in SP value is less than 0.1, the microfibrous cellulose dissolves in the resin, does not function as a filler, and the reinforcing effect cannot be obtained. In this regard, the SP of the resin (solvent) POL Value and SP of microfiber cellulose (solute) MFC The smaller the difference in the values, the greater the reinforcing effect. 3 ) 1 / 2 The SP value is a measure of the intermolecular force acting between a solvent and a solute, and the closer the SP values ​​of the solvent and solute, the greater the solubility.

[0150] (Other compositions) In addition to the above-mentioned fine fibers and pulp, the resin composition can also contain or may contain fibers derived from plant materials obtained from various plants such as kenaf, jute, Manila hemp, sisal, gampi, mitsumata, kozo, banana, pineapple, coconut, corn, sugarcane, bagasse, palm, papyrus, reed, esparto, sabaigrass, wheat, rice, bamboo, various conifers (such as cedar and cypress), broad-leaved trees, and cotton.

[0151] One or more selected from, for example, antistatic agents, flame retardants, antibacterial agents, colorants, radical scavengers, foaming agents, etc. can be added to the resin composition within a range that does not impair the effects of the present invention. These raw materials may be added to a dispersion of fibrous cellulose, added when kneading the fibrous cellulose and resin, added to a kneaded product thereof, or by other methods. However, from the viewpoint of production efficiency, it is preferable to add them when kneading the fibrous cellulose and resin.

[0152] The resin composition may contain an ethylene-α-olefin copolymer elastomer or a styrene-butadiene block copolymer as a rubber component. Examples of α-olefins include butene, isobutene, pentene, hexene, methylpentene, octene, decene, and dodecene.

[0153] (Second additive: ethylene glycol, etc.) When kneading the microfibrous cellulose and resin, in addition to additives such as polybasic acids, at least one additive (second additive) selected from ethylene glycol, ethylene glycol derivatives, ethylene glycol polymers, and ethylene glycol polymer derivatives can be added. Adding this second additive significantly improves the dispersibility of the microfibrous cellulose. In this regard, the present inventors have found that when the cellulose fibers are cellulose nanofibers, it is difficult to improve the dispersibility of the cellulose fibers. However, it is presumed that the second additive enters between the microfibrous cellulose particles, suppressing aggregation in the resin and improving dispersibility. Furthermore, because cellulose nanofibers have a significantly higher specific surface area than microfibrous cellulose, it is presumed that even if an excessive amount of the second additive is added, it will not enter between the cellulose nanofibers.

[0154] The amount of the second additive added is preferably 0.1 to 1,000 parts by mass, more preferably 1 to 500 parts by mass, and particularly preferably 10 to 200 parts by mass, relative to 100 parts by mass of the microfibrous cellulose. If the amount of the second additive added is less than 0.1 part by mass, it may not contribute to improving the dispersibility of the microfibrous cellulose. On the other hand, if the amount of the second additive added is more than 1,000 parts by mass, it may be excessive and may actually reduce the strength of the resin.

[0155] The molecular weight of the second additive is preferably 1 to 20,000, more preferably 10 to 4,000, and particularly preferably 100 to 2,000. It is physically impossible for the molecular weight of the second additive to be less than 1. On the other hand, if the molecular weight of the second additive exceeds 20,000, it becomes bulky and may not be able to fit between the microfiber cellulose particles.

[0156] (molding process) The kneaded mixture of fibrous cellulose and resin can be molded into a desired shape after further kneading, if necessary. The size, thickness, shape, etc. of the molded product are not particularly limited, and may be, for example, a sheet, pellet, powder, fiber, etc.

[0157] The temperature during the molding process is equal to or higher than the glass transition point of the resin, and varies depending on the type of resin, but is, for example, 90 to 260°C, preferably 100 to 240°C.

[0158] The kneaded material can be molded by, for example, mold molding, injection molding, extrusion molding, blow molding, foam molding, etc. Alternatively, the kneaded material can be spun into fibers and mixed with the above-mentioned plant materials to form a mat or board. The mixing can be performed by, for example, simultaneous deposition by air laying.

[0159] As the apparatus for molding the kneaded material, for example, one or more selected from an injection molding machine, a blow molding machine, a hollow molding machine, a blow molding machine, a compression molding machine, an extrusion molding machine, a vacuum molding machine, a pressure molding machine, etc. can be used.

[0160] The molding described above can be carried out following kneading, or the kneaded mixture can be cooled, crushed into chips using a crusher or the like, and then the chips can be fed into a molding machine such as an extrusion molding machine or an injection molding machine. Of course, molding is not an essential requirement of the present invention.

[0161] (Definition, measurement method, etc.) (average fiber diameter) The average fiber diameter of fine fibers (microfiber cellulose and cellulose nanofiber) is measured as follows. First, 100 ml of an aqueous dispersion of fine fibers with a solid content of 0.01 to 0.1% by mass is filtered through a Teflon® membrane filter and solvent-substituted once with 100 ml of ethanol and three times with 20 ml of t-butanol. The sample is then freeze-dried and osmium-coated to obtain a sample. This sample is then observed using an SEM image at a magnification of 3,000x to 30,000x, depending on the width of the fibers that make up the sample. Specifically, two diagonal lines are drawn on the observed image, and three straight lines are arbitrarily drawn passing through the intersections of the diagonal lines. The widths of a total of 100 fibers intersecting with these three straight lines are then visually measured. The median diameter of the measured values ​​is then taken as the average fiber diameter.

[0162] The average fiber diameter of the pulp was measured as follows. First, 100 ml of an aqueous dispersion of pulp with a solid content of 0.01 to 0.1% by mass is filtered through a Teflon® membrane filter and solvent-substituted once with 100 ml of ethanol and three times with 20 ml of t-butanol. The sample is then freeze-dried and osmium-coated to obtain a sample. This sample is then observed using an SEM image at a magnification of 100x to 1000x depending on the width of the fibers that make up the sample. Specifically, two diagonal lines are drawn on the observed image, and three straight lines are arbitrarily drawn passing through the intersections of the diagonal lines. The widths of a total of 100 fibers intersecting with these three straight lines are then visually measured. The median diameter of the measured values ​​is then taken as the average fiber diameter.

[0163] (aspect ratio) The aspect ratio is the average fiber length divided by the average fiber width. The larger the aspect ratio, the more points of snagging occur, which increases the reinforcing effect, but on the other hand, it is thought that the increased snagging reduces the ductility of the resin.

[0164] (Water retention) The water retention is a value measured in accordance with JAPAN TAPPI No. 26 (2000).

[0165] (fiber analysis) The proportion of fibers with a length of 0.2 mm or less, the fibrillation rate, and the average fiber length are measured using a fiber analyzer "FS5" manufactured by Valmet.

[0166] (crystallinity) The crystallinity is a value measured in accordance with JIS K 0131 (1996).

[0167] (viscosity) The pulp viscosity is a value measured in accordance with TAPPI T 230.

[0168] (B type viscosity) The B-type viscosity of the dispersion (solid content 1%) is a value measured in accordance with JIS-Z8803 (2011) "Method for measuring viscosity of liquids." B-type viscosity is the resistance torque when stirring the dispersion, and the higher the viscosity, the more energy is required for stirring.

[0169] (Freeness) The freeness is a value measured in accordance with JIS P8121-2 (2012).

[0170] (degree of substitution) The degree of substitution of carbamate groups was measured by nitrogen determination by the Kjeldahl method. [Example]

[0171] Next, an embodiment of the present invention will be described. 6 g of urea and 79 g of polypropylene powder (PP) were added to 365 g of a microfiber cellulose (MFC) aqueous dispersion with a solids concentration of 2.75 wt %, and the mixture was heated and dried at 105°C to obtain a fibrous cellulose mixture. The moisture content of this fibrous cellulose mixture was less than 10%. This fibrous cellulose mixture was heat-treated at 140°C for 4 hours to carbamate the microfiber cellulose (carbamate-modified).

[0172] 95 g of this carbamate mixture and 5 g of maleic anhydride-modified polypropylene (MAPP) were kneaded in a twin-screw kneader at 180°C and 200 rpm to obtain a fibrous cellulose composite resin. This fibrous cellulose composite resin was cut into cylindrical shapes with a diameter of 2 mm and a length of 2 mm using a pelletizer, and injection-molded into rectangular specimens (length 59 mm, width 9.6 mm, thickness 3.8 mm) at 180°C (Test Example 1). As shown in Table 1, other tests were conducted by varying the blending ratio of the mixture (Other Test Examples). The results of the bending test are shown in Table 1.

[0173] In the bending test, the flexural modulus was first measured in accordance with JIS K7171: 2008. In the table, the flexural modulus of the resin itself was taken as 1, and cases where the flexural modulus (magnification) of the composite resin was 1.3 times or more were marked with "Good", and cases where it was less than 1.3 times were marked with "Poor".

[0174] [Table 1] [Industrial Applicability]

[0175] The present invention can be used as a fibrous cellulose composite resin, a method for producing the same, and a resin reinforcing material. For example, the fibrous cellulose composite resin can be used for interior, exterior, and structural materials for transportation equipment such as automobiles, trains, ships, and airplanes; housings, structural materials, and internal parts for electrical appliances such as personal computers, televisions, telephones, and watches; housings, structural materials, and internal parts for mobile communication devices such as mobile phones; housings, structural materials, and internal parts for portable music players, video players, printing machines, copying machines, sporting goods, office equipment, toys, sporting goods, and the like; interior, exterior, and structural materials for buildings and furniture; office equipment such as stationery; and other applications such as packaging, trays, and other containers, protective materials, and partition members.

Claims

1. The composition comprises fibrous cellulose, a resin, and an acid-modified resin, The fibrous cellulose includes microfibrous cellulose in which some or all of the hydroxyl groups have been substituted with carbamate groups, acid groups of the acid-modified resin ionically bond with some or all of the carbamate groups of the microfibrous cellulose; The microfiber cellulose has an average fiber length of 0.02 to 2.0 mm and an average fiber diameter of 0.1 to 15 μm, The microfiber cellulose has a fiber length of 0.2 mm or less, and the proportion of the fiber length of the microfiber cellulose is 20% or more. The degree of substitution of the carbamate group is 0.05 to 0.5, and the crystallinity of the microfibrous cellulose is 50 to 95%. A fibrous cellulose composite resin characterized by:

2. The acid-modified resin is a maleic anhydride-modified resin. The fibrous cellulose composite resin according to claim 1 .

3. The content of the microfibrous cellulose in the fibrous cellulose is 60 to 100% by mass, The maleic anhydride-modified resin is contained in an amount of 1 to 200 parts by mass per 100 parts by mass of the microfiber cellulose. The fibrous cellulose composite resin according to claim 2.

4. The aspect ratio of the microfiber cellulose is 2 or more. The composite resin according to any one of claims 1 to 3.

5. A cellulose raw material is defibrated to form microfibrous cellulose in which some or all of the hydroxyl groups have been substituted with carbamate groups, and this microfibrous cellulose is kneaded with a resin to produce a fibrous cellulose composite resin, The degree of substitution of the carbamate group is 0.05 to 0.5, and the crystallinity of the microfibrous cellulose is 50 to 95%, The defibration is carried out so that the microfibrous cellulose has an average fiber length of 0.02 to 2.0 mm and an average fiber diameter of 0.1 to 15 μm, The fiber length of the microfiber cellulose is set to 20% or more, and adding an acid-modified resin prior to or during the kneading, and ionic bonding between the acid groups of the acid-modified resin and some or all of the carbamate groups of the microfibrous cellulose; A method for producing a fibrous cellulose composite resin, comprising:

6. The replacement is performed prior to the defibration. The method for producing the fibrous cellulose composite resin according to claim 5.

7. It is a reinforcing material for thermoplastic resins and thermosetting resins, Contains fibrous cellulose and an acid-modified resin, The fibrous cellulose includes microfibrous cellulose in which some or all of the hydroxyl groups have been substituted with carbamate groups, acid groups of the acid-modified resin ionically bond with some or all of the carbamate groups of the microfibrous cellulose; the degree of substitution of the carbamate group is 0.05 to 0.5, and the crystallinity of the microfibrous cellulose is 50 to 95%, The microfiber cellulose has an average fiber length of 0.02 to 2.0 mm, an average fiber diameter of 0.1 to 15 μm, and the proportion of fibers having a length of 0.2 mm or less is 20% or more. A resin reinforcing material characterized by:

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