Resin composition, method for producing resin composition, and resin

Abstract

Provided is a resin composition which contains nanocellulose and a polymer of an ethylenically unsaturated monomer, wherein the nanocellulose includes a cellulose-based feedstock oxide resulting from hypochlorous acid or a salt thereof, does not substantially include an N-oxyl compound, and satisfies the following conditions (I) and / or (II): (I) the zeta potential thereof is -30 mV or less; (II) the light transmittance of a mixture, in which the nanocellulose is mixed with water resulting in a solid content concentration of 0.1 mass%, is 95% or more.

Description

[Technical Field]

[0001] The present invention relates to a resin composition, a method for producing a resin composition, and a resin. [Background technology]

[0002] In recent years, resin materials containing reinforcing materials to enhance their strength have been widely used as lightweight and strong materials. Carbon fiber, glass fiber, and the like are commonly used as reinforcing materials. However, both of these materials are difficult to burn and therefore unsuitable for thermal recycling. Furthermore, carbon fiber is expensive, and glass fiber is heavy.

[0003] Therefore, in recent years, research has been conducted into the use of plant fibers as a reinforcing material for resins. Plant fibers are not artificially synthesized, but are used by breaking down plant-derived fibers. Since plant fibers leave almost no ash when burned, there are no problems with ash disposal in incinerators or landfill disposal. For this reason, research has been conducted in recent years into the use of plant fibers as a reinforcing material for resins, and in particular the use of cellulose nanofibers, which are plant fibers broken down to the nano level, has been studied.

[0004] Because cellulose nanofibers have many hydrophilic functional groups, they have low affinity with resins, and problems have been pointed out, such as the fact that sufficient reinforcing effect cannot be obtained even if they are kneaded directly with resin. As a measure to solve these problems, for example, Patent Document 1 proposes a method in which cellulose nanofibers are mixed into a resin in a state in which they are present on the surface of resin particles, rather than being mixed directly into the resin. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-014741 Summary of the Invention [Problem to be solved by the invention]

[0006] The resin composition of the resin modifier in Patent Document 1 is said to disperse cellulose nanofibers well in the resin to be modified, exhibiting excellent modifying effects and increasing the strength of the resin. However, there is a demand for resin compositions that can further increase the strength of the resin.

[0007] The present invention has been made in view of the above circumstances, and a main object of the present invention is to provide a resin composition having excellent strength. [Means for solving the problem]

[0008] As a result of intensive research to solve the above problems, it was discovered that a resin composition containing a specific nanocellulose can increase the strength of the resin, and this led to the completion of the present invention. Specifically, the present invention provides the following means.

[0009] [1] A resin composition comprising nanocellulose and a polymer of an ethylenically unsaturated monomer, The nanocellulose The oxidation of cellulosic raw materials by hypochlorous acid or its salts is included, Substantially free of N-oxyl compounds, The following (I) and / or (II): (I) Zeta potential is less than -30 mV; (II) The light transmittance of a mixture of nanocellulose and water at a solids concentration of 0.1% by mass is 95% or more; A resin composition that satisfies the above requirements. [2] The zeta potential of the nanocellulose is -70 mV or more. The resin composition according to [1]. [3] The amount of carboxyl groups in the nanocellulose is 0.30 mmol / g or more and less than 2.0 mmol / g, The resin composition according to [1] or [2]. [4] the nanocellulose is derived from oxidized cellulose; The degree of polymerization of the oxidized cellulose is 600 or less. The resin composition according to any one of [1] to [3]. [5] The polymer of the ethylenically unsaturated monomer includes a rubber-modified styrene-based resin. The resin composition according to any one of [1] to [4]. [6] The polymer of the ethylenically unsaturated monomer includes polyvinyl alcohol. The resin composition according to any one of [1] to [4]. [7] The amount of the polymer of the ethylenically unsaturated monomer relative to 100 parts by mass of the nanocellulose is 5 parts by mass or more and 1000 parts by mass or less, The resin composition according to any one of [1] to [6]. [8] At least a portion of the nanocellulose is modified with a metal soap, an amine, or a quaternary ammonium; The resin composition according to any one of [1] to [7]. [9] A method for producing a resin composition, comprising a step of polymerizing an ethylenically unsaturated monomer in the presence of nanocellulose, The nanocellulose It is an oxidation of cellulosic raw materials with hypochlorous acid or its salts, Substantially free of N-oxyl compounds, The following (I) and / or (II): (I) Zeta potential is less than -30 mV; (II) The light transmittance of a mixture of nanocellulose and water at a solids concentration of 0.1% by mass is 95% or more; Manufacturing method that meets the above requirements.

[10] The polymerization method is emulsion polymerization or suspension polymerization. [The manufacturing method described in 9.

[11] A method for producing a resin composition containing nanocellulose and a polymer of an ethylenically unsaturated monomer, A step of agitating a first mixture containing oxidized cellulose and an ethylenically unsaturated monomer to obtain a second mixture containing nanocellulose and a polymer of an ethylenically unsaturated monomer; and polymerizing an ethylenically unsaturated monomer using the second mixture, The method for producing the oxidized cellulose comprises an oxidation product of a cellulosic raw material with hypochlorous acid or a salt thereof.

[12] A method for producing a resin composition containing nanocellulose and a polymer of an ethylenically unsaturated monomer, A step of stirring the oxidized cellulose and continuously adding an ethylenically unsaturated monomer to obtain a mixture comprising nanocellulose and an ethylenically unsaturated monomer; and polymerizing an ethylenically unsaturated monomer using the mixture, The method for producing the oxidized cellulose comprises an oxidation product of a cellulosic raw material with hypochlorous acid or a salt thereof.

[13] The polymerization method is emulsion polymerization or suspension polymerization.

[11] or

[12] .

[14] A method for producing a resin composition containing nanocellulose and a polymer of an ethylenically unsaturated monomer, The method includes a step of obtaining a resin composition containing nanocellulose and a polymer of an ethylenically unsaturated monomer by stirring a first mixture containing oxidized cellulose and a polymer of an ethylenically unsaturated monomer, The method for producing the oxidized cellulose comprises an oxidation product of a cellulosic raw material with hypochlorous acid or a salt thereof.

[15] A method for producing a resin composition containing nanocellulose and a polymer of an ethylenically unsaturated monomer, The method includes a step of stirring the oxidized cellulose and continuously adding a polymer of an ethylenically unsaturated monomer to obtain a resin composition containing the nanocellulose and the polymer of an ethylenically unsaturated monomer, The method for producing the oxidized cellulose comprises an oxidation product of a cellulosic raw material with hypochlorous acid or a salt thereof.

[16] the oxidized cellulose is substantially free of N-oxyl compounds; The manufacturing method according to any one of

[11] to

[15] .

[17] The degree of polymerization of the oxidized cellulose is 600 or less. The manufacturing method according to any one of

[11] to

[16] .

[18] The method further comprises precipitating the nanocellulose and ethylenically unsaturated monomer by adding a metal soap, an amine, or a quaternary ammonium; The manufacturing method according to any one of

[11] to

[17] .

[19] A resin comprising the resin composition according to any one of [1] to [8].

[20] A polyvinyl alcohol film produced from the resin composition according to [6]. [Effects of the Invention]

[0010] According to the present invention, a resin composition having excellent strength can be provided. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 shows the results of breaking strain and breaking stress. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In the following embodiments, components (including element steps, etc.) are not essential unless otherwise specified. The same applies to numerical values and their ranges, and do not limit the present invention. In the present disclosure, the term "process" includes not only a process that is independent of other processes, but also a process that cannot be clearly distinguished from other processes as long as the purpose of the process is achieved. In the present disclosure, numerical ranges indicated using "to" include the numerical values before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this disclosure, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in the present disclosure, the upper or lower limit of the numerical ranges may be replaced with values shown in the examples. In the present disclosure, each component may contain multiple substances corresponding to the component. When multiple substances corresponding to each component are present in the composition, the content or amount of each component means the total content or amount of the multiple substances present in the composition, unless otherwise specified. In the present disclosure, the composition may contain multiple types of particles corresponding to each component. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified. In the present disclosure, "(meth)acrylic" means at least one of acrylic and methacrylic, and "(meth)acrylate" means at least one of acrylate and methacrylate.

[0013] <Resin composition> The resin composition of the present invention contains nanocellulose and a polymer of an ethylenically unsaturated monomer. The nanocellulose contains an oxide of a cellulose-based raw material with hypochlorous acid or a salt thereof, and is substantially free of N-oxyl compounds. The nanocellulose also satisfies the following (I) and / or (II): (I) Zeta potential is less than -30 mV; (II) The light transmittance of a mixture of nanocellulose and water at a solids concentration of 0.1% by mass is 95% or more;

[0014] The resin composition of the present invention refers to a composition that primarily contains a polymer of an ethylenically unsaturated monomer as a constituent resin. Here, "primarily containing a polymer of an ethylenically unsaturated monomer as a constituent resin" means that the proportion of the polymer of the ethylenically unsaturated monomer relative to the total amount of resins that constitute the composition typically exceeds 50% by mass. This proportion may be 60% by mass or more, more than 70% by mass, more than 80% by mass, more than 90% by mass, more than 95% by mass, or even 100% by mass.

[0015] The form of the resin composition of the present invention is not particularly limited, and may be, for example, in the form of powder, pellets, or lumps. The resin composition of the present invention may be used by molding the powder, pellets, or lumps as they are. The resin composition of the present invention may also be used by mixing the powder, pellets, or lumps with the resin to be blended with the resin composition (hereinafter also referred to as raw resin). When the resin composition is blended with the raw resin, the resin composition is also referred to as a resin modifying composition. That is, the resin composition of the present invention includes both an embodiment in which the resin itself is used as a resin and an embodiment in which the resin composition is used as a resin modifying composition.

[0016] The resin composition of the present invention contains nanocellulose that contains an oxide of a cellulosic raw material with hypochlorous acid or its salt, is substantially free of N-oxyl compounds, and satisfies (I) and / or (II). As described in detail in the "Method for Producing Nanocellulose" section below, such nanocellulose can be obtained by oxidizing a cellulosic raw material with hypochlorous acid or its salt to obtain oxidized cellulose (i.e., an oxide of the cellulosic raw material), and then defibrating this oxidized cellulose. In this method, the oxidized cellulose exhibits easy defibration properties, and this defibration process sufficiently progresses, improving the dispersibility of the resulting nanocellulose. The resin composition of the present invention can also be obtained by blending the oxidized cellulose with a resin or resin raw material, appropriately defibrating it, and nano-sizing it to form a composite of nanocellulose and a polymer of an ethylenically unsaturated monomer. When this nanocellulose is compounded with a polymer of an ethylenically unsaturated monomer, a resin composition is obtained in which the nanocellulose is uniformly dispersed in the polymer. As a result, the resin composition of the present invention is thought to have fine cellulose dispersed uniformly in the resin, resulting in a resin with strength, specifically, strength in terms of flexural modulus and impact resistance.

[0017] [Nanocellulose] The nanocellulose of the present invention is a nano-sized version of oxidized cellulose obtained by oxidizing a cellulosic raw material with hypochlorous acid or its salts. Here, the oxidized cellulose can also be referred to as an oxide of the cellulosic raw material. Therefore, the nanocellulose of the present invention includes an oxide of the cellulosic raw material with hypochlorous acid or its salts. The main component of plants is cellulose, and bundles of cellulose molecules are called cellulose microfibrils. The cellulose in cellulosic raw materials is also contained in the form of cellulose microfibrils. The nanocellulose of the present invention is a general term for nano-sized cellulose, including fine cellulose fibers and cellulose nanocrystals, as well as modified forms of these (details of the modified forms will be described later). Fine cellulose fibers are also called cellulose nanofibers (also referred to as CNF).

[0018] The nanocellulose of the present invention can be produced by a production method comprising the steps of: oxidizing a cellulosic raw material using hypochlorous acid or a salt thereof with an available chlorine concentration of 7% to 43% by mass to produce oxidized cellulose; and, if necessary, defibrating the oxidized cellulose to form nano-sized particles. The nanocellulose of the present invention can be suitably obtained, for example, by oxidizing a cellulosic raw material under conditions in which the available chlorine concentration of hypochlorous acid or a salt thereof in the reaction system is relatively high (e.g., 14% to 43% by mass), and then defibrating the oxidized cellulose as necessary. The resin composition of the present invention contains nanocellulose, but it can also be produced by blending oxidized cellulose that has been defibrated and nanosized, or by using oxidized cellulose as a raw material during the preparation of the resin composition and nanoizing the oxidized cellulose during the preparation. Thus, the nanocellulose in the resin composition has been nanosized at an appropriate time.

[0019] In the production of nanocellulose in the present invention, N-oxyl compounds such as TEMPO are not used in the process of oxidizing cellulosic raw materials with hypochlorous acid or its salts. Therefore, the nanocellulose or oxidized cellulose in the present invention is substantially free of N-oxyl compounds. Therefore, nanocellulose is highly safe because the impact of N-oxyl compounds on the environment and human body is sufficiently reduced. Here, in this specification, nanocellulose or oxidized cellulose "substantially free of N-oxyl compounds" means that no N-oxyl compounds are used in the production of oxidized cellulose, or the content of N-oxyl compounds is 2.0 ppm by mass or less, preferably 1.0 ppm by mass or less, relative to the total amount of nanocellulose. Furthermore, "substantially free of N-oxyl compounds" also means that the content of N-oxyl compounds is preferably 2.0 ppm by mass or less, more preferably 1.0 ppm by mass or less, as an increase from the cellulosic raw material. The content of N-oxyl compounds can be measured by known means. Examples of known means include a method using a trace total nitrogen analyzer. Specifically, the nitrogen component derived from N-oxyl compounds in nanocellulose can be measured as the amount of nitrogen using a trace total nitrogen analyzer (e.g., Mitsubishi Chemical Analytical Co., Ltd., device name: TN-2100H, etc.).

[0020] The oxidized cellulose has excellent defibration properties. In particular, the oxidized cellulose can be uniformly pulverized even when defibrated under mild conditions, demonstrating excellent defibration properties. Furthermore, when mixed with the nanocellulose to form a slurry, the slurry viscosity remains stable over time and is easy to handle. The nanocellulose of the present invention can be produced by an oxidation reaction using hypochlorous acid or a salt thereof, as described in detail in the "Method for producing nanocellulose" below, and satisfies the following zeta potential and light transmittance. The zeta potential and light transmittance can be used as indicators of nanocellulose.

[0021] (zeta potential) The nanocellulose of the present invention has a zeta potential of -30 mV or less. When the zeta potential is -30 mV or less (i.e., an absolute value of 30 mV or more), sufficient repulsion between microfibrils is obtained, making it easier to produce nanocellulose with a high surface charge density during mechanical defibration. This improves the dispersion stability of the nanocellulose, and makes it possible to obtain a slurry with excellent viscosity stability and handleability. When the zeta potential is -100 mV or higher (i.e., the absolute value is 100 mV or lower), oxidative scission in the fiber direction as oxidation progresses tends to be suppressed, making it possible to obtain nanocellulose of uniform size, increasing the stability and dispersibility of the nanocellulose, and ensuring that the nanocellulose is uniformly contained in the resulting resin composition.

[0022] From the above viewpoint, the zeta potential of nanocellulose is preferably -35 mV or less, more preferably -40 mV or less, and even more preferably -50 mV or less. Furthermore, the lower limit of the zeta potential is preferably -90 mV or more, more preferably -85 mV or more, even more preferably -80 mV or more, even more preferably -77 mV or more, even more preferably -70 mV or more, and even more preferably -65 mV or more. Preferably, it is -90 mV or more and -30 mV or less, more preferably -85 mV or more and -30 mV or less, even more preferably -80 mV or more and -30 mV or less, even more preferably -77 mV or more and -30 mV or less, even more preferably -70 mV or more and -30 mV or less, even more preferably -65 mV or more and -35 mV or less. In this specification, the zeta potential is a value measured on an aqueous cellulose dispersion prepared by mixing nanocellulose and water to a nanocellulose concentration of 0.1% by mass at a pH of 8.0 and 20°C. Specifically, it can be measured according to the conditions described in the examples below.

[0023] (light transmittance) The nanocellulose dispersion of the present invention, in which nanocellulose with narrow fiber width and few aggregates is dispersed in a dispersion medium, exhibits little light scattering by the cellulose fibers and high light transmittance. Specifically, the nanocellulose of the present invention has a light transmittance of 95% or more in a mixed solution when mixed with water to a solids concentration of 0.1% by mass. The light transmittance is more preferably 96% or more, and even more preferably 97% or more. The light transmittance is a value measured at a wavelength of 660 nm using a spectrophotometer. The light transmittance can also be measured using an aqueous dispersion containing nanocellulose. Specifically, the measurement can be carried out under the conditions described in the Examples below.

[0024] As described above, the nanocellulose in the present invention is obtained by obtaining oxidized cellulose using hypochlorous acid or a salt thereof and then defibrating the oxidized cellulose. Here, the degree of polymerization of the oxidized cellulose used in the present invention is preferably 600 or less. When the degree of polymerization of oxidized cellulose exceeds 600, a large amount of energy tends to be required for defibration, making it impossible to exhibit sufficient defibration properties, resulting in decreased dispersibility and ultimately decreased resin strength. Furthermore, when the degree of polymerization of oxidized cellulose exceeds 600, a large amount of oxidized cellulose is insufficiently defibrated. Therefore, when this oxidized cellulose is finely defibrated to form nanocellulose, and the resulting oxidized cellulose is dispersed in a dispersion medium, light scattering and other problems can increase, resulting in decreased transparency. Furthermore, the size of the resulting nanocellulose tends to vary, resulting in non-uniform quality. This can increase the viscosity of a slurry containing nanocellulose (hereinafter also referred to as "nanocellulose-containing slurry") and may reduce the handleability of the slurry. From the viewpoint of defibration properties, no lower limit for the degree of polymerization of oxidized cellulose is specifically set. However, when the degree of polymerization of oxidized cellulose is less than 50, the proportion of particulate cellulose rather than fibrous cellulose increases, potentially reducing the reinforcing effect when added to a resin. From the above viewpoints, the degree of polymerization of oxidized cellulose is preferably in the range of 50 to 600.

[0025] The degree of polymerization of the oxidized cellulose is more preferably 580 or less, even more preferably 560 or less, still more preferably 550 or less, even more preferably 500 or less, even more preferably 450 or less, and even more preferably 400 or less. From the viewpoint of improving the viscosity stability of the slurry, the lower limit of the degree of polymerization is more preferably 60 or more, even more preferably 70 or more, even more preferably 80 or more, even more preferably 90 or more, even more preferably 100 or more, even more preferably 110 or more, and particularly preferably 120 or more. A preferred range of the degree of polymerization can be determined by appropriately combining the above-mentioned upper and lower limits. The degree of polymerization of the oxidized cellulose is more preferably 60 to 600, even more preferably 70 to 600, even more preferably 80 to 600, even more preferably 80 to 550, even more preferably 80 to 500, even more preferably 80 to 450, and particularly preferably 80 to 400.

[0026] The degree of polymerization of oxidized cellulose can be adjusted by changing the reaction time, reaction temperature, pH, and available chlorine concentration of hypochlorous acid or its salt during the oxidation reaction. Specifically, since an increase in the degree of oxidation tends to decrease the degree of polymerization, methods for decreasing the degree of polymerization include increasing the oxidation reaction time and / or reaction temperature. Alternatively, the degree of polymerization of oxidized cellulose can be adjusted by changing the stirring conditions of the reaction system during the oxidation reaction. For example, under conditions where the reaction system is sufficiently homogenized using a stirring blade or the like, the oxidation reaction proceeds smoothly and the degree of polymerization tends to decrease. On the other hand, under conditions where the reaction system is likely to be insufficiently stirred, such as stirring with a stirrer, the reaction tends to become non-uniform, making it difficult to sufficiently reduce the degree of polymerization of oxidized cellulose. Furthermore, the degree of polymerization of oxidized cellulose tends to vary depending on the selection of raw cellulose. Therefore, the degree of polymerization of oxidized cellulose can also be adjusted by selecting the appropriate cellulosic raw material. In this specification, the degree of polymerization of oxidized cellulose is the average degree of polymerization (viscosity-average degree of polymerization) measured by a viscosity method. Details are given in accordance with the method described in the Examples below.

[0027] (carboxyl group amount) The carboxyl group amount of nanocellulose and oxidized cellulose is preferably 0.30 mmol / g or more but less than 2.0 mmol / g. A carboxyl group amount of 0.30 mmol / g or more can impart sufficient defibration properties to oxidized cellulose. This allows for the production of nanocellulose-containing slurries of uniform quality even when defibration treatment is performed under mild conditions, improving the viscosity stability and handleability of the slurry. On the other hand, a carboxyl group amount of less than 2.0 mmol / g can prevent excessive decomposition of cellulose during defibration treatment, resulting in the production of nanocellulose of uniform quality with a low proportion of particulate cellulose. This is thought to improve dispersibility and increase the strength of resins containing nanocellulose. From this perspective, the carboxyl group amount of oxidized cellulose is more preferably 0.35 mmol / g or more, even more preferably 0.40 mmol / g or more, even more preferably 0.42 mmol / g or more, even more preferably 0.50 mmol / g or more, even more preferably greater than 0.50 mmol / g, and even more preferably 0.55 mmol / g or more. The upper limit of the carboxyl group amount is more preferably 1.5 mmol / g or less, even more preferably 1.2 mmol / g, even more preferably 1.0 mmol / g or less, and even more preferably 0.9 mmol / g. A preferred range of the carboxyl group amount can be determined by appropriately combining the above-mentioned upper and lower limits. The carboxyl group amount of the present oxidized cellulose is more preferably 0.35 to 2.0 mmol / g, even more preferably 0.35 to 1.5 mmol / g, even more preferably 0.40 to 1.5 mmol / g, even more preferably 0.50 to 1.2 mmol / g, even more preferably more than 0.50 to 1.2 mmol / g, and even more preferably 0.55 to 1.0 mmol / g.

[0028] The amount of carboxyl groups (mmol / g) was calculated using the following formula from the amount of sodium hydroxide (a) consumed in the neutralization stage of weak acid, where the change in electrical conductivity is gradual, after adding 0.1 M hydrochloric acid aqueous solution to an aqueous solution prepared by mixing oxidized cellulose with water to adjust the pH to 2.5, and then adding 0.05 N sodium hydroxide aqueous solution dropwise and measuring the electrical conductivity until the pH reaches 11.0. Details are given in accordance with the method described in the Examples below. The amount of carboxyl groups can be adjusted by changing the reaction time, reaction temperature, pH of the reaction solution, etc. of the oxidation reaction. Amount of carboxyl group = a (ml) x 0.05 / mass of oxidized cellulose (g)

[0029] The oxidized cellulose preferably has a structure in which at least two of the hydroxyl groups on the glucopyranose ring that constitutes the cellulose have been oxidized, more specifically, the hydroxyl groups at positions 2 and 3 of the glucopyranose ring have been oxidized and carboxyl groups have been introduced. Furthermore, the hydroxyl group at position 6 of the glucopyranose ring in the oxidized cellulose is preferably not oxidized and remains as a hydroxyl group. The position of the carboxy group in the glucopyranose ring was confirmed by the solution NMR spectrum of oxidized rayon as a model molecule and the solid NMR spectrum of oxidized cellulose. 13 It can be analyzed by comparing C-NMR spectra.

[0030] Rayon has the same chemical structure as cellulose, and its oxide (rayon oxide) is water-soluble. 13 C-NMR measurements reveal a carbon peak attributable to carboxy groups at 165 to 185 ppm. In one embodiment of the oxidized cellulose or nanocellulose used in the present invention, obtained by oxidizing raw cellulose with hypochlorous acid or its salt, two signals appear within this chemical shift range. Furthermore, solution two-dimensional NMR measurements reveal that carboxy groups have been introduced at the 2- and 3-positions.

[0031] Oxidized cellulose or nanocellulose solid obtained by oxidizing raw cellulose with hypochlorous acid or its salts 13 In C-NMR, when the amount of carboxyl groups introduced is large, two signals appear at 165 to 185 ppm, and when the amount of carboxyl groups introduced is small, a very broad signal may appear. As can be seen from the results for oxidized rayon, the signals of the carboxyl group carbons introduced at the 2nd and 3rd positions are close to each other, and this is difficult to achieve with low-resolution solid state spectroscopy. 13 In C-NMR, the separation of the two signals is insufficient. Therefore, when the amount of carboxyl group introduced is small, a broad signal is observed. 13 In the C-NMR spectrum, the introduction of carboxy groups at the 2nd and 3rd positions can be confirmed by evaluating the broadening of the peaks appearing at 165 to 185 ppm. That is, solid 13 A baseline is drawn around the peak in the range of 165 ppm to 185 ppm in the C-NMR spectrum to determine the overall area value, and then the area value is vertically divided at the peak top to determine the ratio of the two peak area values (large area value / small area value). If the ratio of the peak area values is 1.2 or more, the peak can be said to be broad. The presence or absence of the broad peak can be determined by the ratio of the length L of the baseline in the range of 165 ppm to 185 ppm to the length L' of the perpendicular line from the peak top to the baseline. That is, if the ratio L' / L is 0.1 or more, it can be determined that a broad peak is present. The ratio L' / L may be 0.2 or more, 0.3 or more, 0.4 or more, or even 0.5 or more. There is no particular upper limit to the ratio L' / L, but it is usually 3.0 or less, and may be 2.0 or less, or 1.0 or less. The structure of the glucopyranose ring can also be determined by analysis according to the method described in Sustainable Chem. Eng. 2020, 8, 48, 17800-17806.

[0032] The nanocellulose of the present invention is an aggregate of individual fibers. When the nanocellulose of the present invention contains carboxylated CNF, it is sufficient that it contains at least one carboxylated CNF, and it is preferable that the carboxylated CNF is the main component. Here, "carboxylated CNF is the main component" means that the proportion of carboxylated CNF in the total amount of CNF exceeds 50% by mass, preferably exceeds 70% by mass, and more preferably exceeds 80% by mass. The upper limit of the above proportion is 100% by mass, but it may also be 98% by mass or 95% by mass.

[0033] The average fiber length of the nanocellulose in the present invention is preferably 100 nm or more and 700 nm or less, and the average fiber width of the nanocellulose in the present invention is preferably 1.0 nm or more and 5.0 nm or less.

[0034] The average fiber length is preferably in the range of 100 nm to 600 nm, and even more preferably in the range of 100 nm to 400 nm. If the average fiber length exceeds 700 nm, the slurry will become significantly thickened and difficult to handle. Also, if the average fiber length is less than 100 nm, the viscosity characteristic of nanocellulose will not be fully realized.

[0035] The average fiber width is preferably 2.0 nm to 5.0 nm, more preferably 2.0 nm to 4.5 nm, and even more preferably 2.5 nm to 4.0 nm. If the average fiber width is less than 1.0 nm, the strength of the resin containing nanocellulose is less likely to be improved. If the average fiber width is greater than 5.0 nm, stress concentration will likely result in less strength improvement. The average fiber length and average fiber width were calculated by mixing nanocellulose with water to a nanocellulose concentration of approximately 1 to 10 ppm, air-drying the resulting diluted nanocellulose aqueous dispersion on a mica substrate, observing the shape of the nanocellulose using a scanning probe microscope, randomly selecting any number of fibers from the obtained image, and calculating the fiber length (perimeter of the shape image divided by 2) and the fiber width (cross-sectional height of the shape image). Image processing software can be used to calculate these average fiber widths and average fiber lengths. While the image processing conditions are arbitrary, differences in calculated values may occur even for the same image depending on the image processing conditions. The range of difference in values depending on the image processing conditions is preferably within ±100 nm for average fiber length. The range of difference in values depending on the conditions is preferably within ±10 nm for average fiber width. More detailed measurement methods follow the methods described in the Examples below.

[0036] As described below, the resin composition of the present invention may include a step of adding a metal soap, amine, or quaternary ammonium to precipitate the resin composition as needed. This results in at least a portion of the nanocellulose being modified by the metal soap, amine, or quaternary ammonium. Furthermore, when producing the resin composition of the present invention, nanocellulose that has been previously reacted with a metal soap, amine, or quaternary ammonium may be used, thereby modifying at least a portion of the nanocellulose with the metal soap, amine, or quaternary ammonium. Therefore, one preferred embodiment of the resin composition of the present invention contains nanocellulose in which at least a portion of the nanocellulose is modified with a metal soap, an amine, or a quaternary ammonium.

[0037] It is believed that the reaction of metal soaps, amines, or quaternary ammonium salt compounds with the carboxyl groups on the surface of nanocellulose modifies the nanocellulose, improving its hydrophobicity and its affinity for ethylenically unsaturated monomers and resins.

[0038] Metal soaps that modify nanocellulose are not particularly limited and include, for example, metal salts of long-chain fatty acids such as magnesium salts of long-chain fatty acids, calcium salts of long-chain fatty acids, and zinc salts of long-chain fatty acids; mixtures of calcium salts of long-chain fatty acids and zinc salts of long-chain fatty acids; and lead-based metal soaps. Among these, metal salts of long-chain fatty acids are preferred. Furthermore, metal polyvalent salts of long-chain fatty acids are preferred as metal salts of long-chain fatty acids. Examples of long-chain fatty acids include butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, isostearic acid, stearic acid, oleic acid, linoleic acid, ricinoleic acid, octylic acid, arachidic acid, arachidonic acid, behenic acid, lignoceric acid, and montanic acid. More preferred metal soaps include magnesium stearate, mixtures of calcium stearate and zinc stearate, and lead-based thermal metal soaps. These metal soaps may be used alone or in combination of two or more. As the metal soap, commercially available products containing the above-mentioned metal soap may be used. Examples of commercially available products include RZ-161, RZ-162, MDZ-CP-102, FTZ-111, SCI-HSA-M1, SAK-CS-P, SAK-CS-G, SAK-CS-P-1 / USP, SAK-CS-PPT, SAK-CS-GPT-1, SAK-CS-POF, SAK-CS-PLB, SAK-CS-PC, SAK-ZS-P, SAK-ZS-TB, SAK-ZS-PLB500, SAK-ZS-TPS, and SAK-CS-P, manufactured by San-Ace. Examples include AK-ZS-TBPS, SAK-MS-P, SAK-MS-P / USP, SCI-HCS, SCI-HCS-SG, SCI-HCS-AB, SCI-HZS, SCI-HMS, SCI-ZNB, SAK-NAS-P, SAK-KS-CP, SAK-ZL-P, SCI-LIS, FerricStearate83X, Sakai Chemical Industry's LHR-200 series, LHR-300 series, LHR-400 series, and Nitto Kasei Kogyo's HT-series, PSL series, SR series, and TR series.

[0039] The amine used to modify nanocellulose is not particularly limited and may be primary, secondary, or tertiary. The number of carbon atoms in the hydrocarbon or aromatic group bonded to the nitrogen atom of the amine or quaternary ammonium salt compound (when two or more hydrocarbon or aromatic groups are bonded to the nitrogen atom, the total carbon number) is not particularly limited and may be selected from between 1 and 100 carbon atoms. As the amine, an amine having a polyalkylene oxide structure such as an ethylene oxide / propylene oxide (EO / PO) copolymer moiety may also be used. From the viewpoint of imparting sufficient hydrophobicity to nanocellulose, the number of carbon atoms is preferably 3 or more, and more preferably 5 or more.

[0040] The quaternary ammonium salt compound that modifies nanocellulose is not particularly limited. Specific examples of the quaternary ammonium salt compound include quaternary ammonium hydroxides such as tetrabutylammonium hydroxide, quaternary ammonium chlorides such as tetrabutylammonium chloride, quaternary ammonium bromides such as tetrabutylammonium bromide, and quaternary ammonium iodides such as tetrabutylammonium iodide.

[0041] Nanocellulose reacted with metal soap, amine, or quaternary ammonium salt compound functions as a dispersant in the process of polymerizing ethylenically unsaturated monomers. This allows the use of an emulsifier to be omitted in the process of polymerizing ethylenically unsaturated monomers. Not using an emulsifier is advantageous in terms of workability, as foaming does not occur when the resulting resin composition is dried.

[0042] [Method of manufacturing nanocellulose] Next, we will explain the method for producing nanocellulose. Nanocellulose in the present invention can be produced, for example, by a method including step A of oxidizing a cellulosic raw material with hypochlorous acid or a salt thereof to obtain oxidized cellulose, and step B of defibrating the oxidized cellulose.

[0043] (Step A: Production of oxidized cellulose) The cellulosic raw material is not particularly limited as long as it is a material primarily composed of cellulose, and examples thereof include pulp, natural cellulose, regenerated cellulose, and fine cellulose obtained by depolymerizing cellulose through mechanical processing. Commercially available cellulosic raw materials, such as crystalline cellulose derived from pulp, can be used as they are. Alternatively, unused biomass containing a large amount of cellulose components, such as soybean pulp refuse or soybean hulls, can also be used as the raw material. Furthermore, the cellulosic raw material may be pre-treated with an alkali of an appropriate concentration in order to facilitate the penetration of the oxidizing agent used into the raw pulp.

[0044] Examples of hypochlorous acid or a salt thereof used for oxidizing a cellulosic raw material include hypochlorous acid water, sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, and ammonium hypochlorite. Among these, sodium hypochlorite is preferred from the viewpoint of ease of handling.

[0045] Methods for producing oxidized cellulose by oxidation of a cellulosic raw material include mixing the cellulosic raw material with a reaction solution containing hypochlorous acid or a salt thereof. Water is preferred as the solvent contained in the reaction solution, as it is easy to handle and unlikely to cause side reactions. The available chlorine concentration of hypochlorous acid or a salt thereof in the reaction solution is preferably 6 to 43% by mass, more preferably 7 to 43% by mass, even more preferably 10 to 43% by mass, and even more preferably 14 to 43% by mass. When the available chlorine concentration of the reaction solution is within the above range, the amount of carboxy groups in the oxidized cellulose can be sufficiently increased, making it easy to defibrate the oxidized cellulose when obtaining nanocellulose.

[0046] From the viewpoint of sufficiently increasing the amount of carboxy groups in the oxidized cellulose, the available chlorine concentration of the reaction solution is more preferably 15% by mass or more, even more preferably 18% by mass or more, and even more preferably 20% by mass or more. Furthermore, from the viewpoint of suppressing excessive decomposition of cellulose during defibration, the available chlorine concentration of the reaction solution is more preferably 40% by mass or less, and even more preferably 38% by mass or less. The range of the available chlorine concentration of the reaction solution can be any combination of the above-mentioned lower and upper limits. The range of the available chlorine concentration is more preferably 16 to 43% by mass, and even more preferably 18 to 40% by mass.

[0047] The available chlorine concentration of hypochlorous acid or its salts is defined as follows: Hypochlorous acid is a weak acid that exists as an aqueous solution, and hypochlorite is a compound in which the hydrogen of hypochlorous acid is replaced by another cation. For example, sodium hypochlorite, a hypochlorite, exists in a solvent (preferably in an aqueous solution), so the concentration is measured as the amount of available chlorine in the solution, not the concentration of sodium hypochlorite. Here, with regard to the available chlorine of sodium hypochlorite, the oxidizing power of the divalent oxygen atom generated by the decomposition of sodium hypochlorite is equivalent to two atomic equivalents of monovalent chlorine, so the bonded chlorine atoms of sodium hypochlorite (NaClO) have the same oxidizing power as two atoms of unbonded chlorine (Cl2), and the available chlorine = 2 × (chlorine in NaClO). The specific measurement procedure is as follows: First, the sample is precisely weighed, and water, potassium iodide, and acetic acid are added and left to stand. The liberated iodine is titrated with a sodium thiosulfate solution using a starch aqueous solution as an indicator to measure the available chlorine concentration.

[0048] The oxidation reaction of the cellulosic raw material with hypochlorous acid or a salt thereof is preferably carried out while adjusting the pH to the range of 5.0 to 14.0. Within this range, the oxidation reaction of the cellulosic raw material can be sufficiently progressed, and the amount of carboxy groups in the oxidized cellulose can be sufficiently increased. This facilitates defibration of the oxidized cellulose. The pH of the reaction system is more preferably 7.0 or higher, and even more preferably 8.0 or higher. The upper limit of the pH of the reaction system is more preferably 13.5 or lower, and even more preferably 13.0 or lower. The pH range of the reaction system is more preferably 7.0 to 14.0, and even more preferably 8.0 to 13.5.

[0049] Hereinafter, the method for producing oxidized cellulose will be further explained using as an example the case where sodium hypochlorite is used as hypochlorous acid or a salt thereof.

[0050] When oxidizing a cellulosic raw material using sodium hypochlorite, the reaction liquid is preferably a sodium hypochlorite aqueous solution. Methods for adjusting the effective chlorine concentration of a sodium hypochlorite aqueous solution to a target concentration (for example, target concentration: 6% by mass to 43% by mass) include concentrating a sodium hypochlorite aqueous solution having a lower effective chlorine concentration than the target concentration, diluting a sodium hypochlorite aqueous solution having a higher effective chlorine concentration than the target concentration, and dissolving sodium hypochlorite crystals (for example, sodium hypochlorite pentahydrate) in a solvent. Among these, the method of diluting a sodium hypochlorite aqueous solution or dissolving sodium hypochlorite crystals in a solvent to adjust the effective chlorine concentration as an oxidizing agent is preferred because it causes less self-decomposition (i.e., less reduction in effective chlorine concentration) and is easy to adjust the effective chlorine concentration.

[0051] The method for mixing the cellulosic raw material with the aqueous sodium hypochlorite solution is not particularly limited, but from the viewpoint of ease of operation, it is preferable to add the cellulosic raw material to the aqueous sodium hypochlorite solution and mix them.

[0052] To efficiently promote the oxidation reaction of the cellulosic raw material, it is preferable to stir the mixture of the cellulosic raw material and the aqueous sodium hypochlorite solution during the oxidation reaction. Examples of stirring methods include a magnetic stirrer, a stirring rod, a stirrer with stirring blades (Three-One Motor), a homomixer, a disperser-type mixer, a homogenizer, and external circulation stirring. Among these, methods using one or more of shear-type stirrers such as homomixers and homogenizers, stirrers with stirring blades, and disperser-type mixers are preferred, as they allow the oxidation reaction of the cellulosic raw material to proceed smoothly and make it easy to adjust the degree of polymerization of oxidized cellulose to a predetermined value or less. Methods using a stirrer with stirring blades are particularly preferred. When using a stirrer with stirring blades, devices equipped with known stirring blades such as propeller blades, paddle blades, and turbine blades can be used. Furthermore, when using a stirrer with stirring blades, stirring is preferably performed at a rotation speed of 50 to 300 rpm.

[0053] The reaction temperature in the oxidation reaction is preferably 15°C to 100°C, and more preferably 20°C to 90°C. During the reaction, the pH of the reaction system decreases as carboxyl groups are generated in the cellulosic raw material by the oxidation reaction. Therefore, from the viewpoint of efficiently progressing the oxidation reaction, it is preferable to add an alkaline agent (e.g., sodium hydroxide) or an acid (e.g., hydrochloric acid) to the reaction system to adjust the pH of the reaction system to the above-mentioned preferred range. The reaction time of the oxidation reaction can be set according to the degree of progress of the oxidation, but is preferably about 15 minutes to 50 hours. When the pH of the reaction system is to be 10 or higher, it is preferable to set the reaction temperature to 30°C or higher and / or the reaction time to 30 minutes or longer.

[0054] The zeta potential and light transmittance of nanocellulose can be adjusted to desired values by adjusting the reaction time, reaction temperature, stirring conditions, etc. of the oxidation reaction. Specifically, as the reaction time is extended and / or the reaction temperature is increased, oxidation of the surface of cellulose microfibrils in the cellulosic raw material progresses, and the repulsion between fibrils due to electrostatic repulsion and osmotic pressure increases, tending to result in a smaller average fiber width. Furthermore, the zeta potential tends to increase by setting one or more of the oxidation reaction time, reaction temperature, and stirring conditions (e.g., by extending the reaction time) to promote oxidation (i.e., to increase the degree of oxidation).

[0055] The solution containing oxidized cellulose obtained by the above reaction can be subjected to known isolation treatments such as filtration, and further purified as necessary to obtain oxidized cellulose as an oxide of a cellulosic raw material with hypochlorous acid or a salt thereof. The solution containing oxidized cellulose obtained by the above reaction may also be subjected to defibration treatment as is. When the pH of the solution containing oxidized cellulose is adjusted to 4.0 or less for the isolation treatment, in order to improve the handling when the solution is used for the subsequent defibration treatment, for example, a base is added to adjust the pH to 6.0 or more, and at least a portion of the carboxyl groups are converted to a salt form (-COO - X + :X + (represents a cation such as sodium, potassium, or lithium). Furthermore, a solution containing oxidized cellulose may be converted into a composition containing oxidized cellulose by, for example, replacing the solvent. In a composition containing oxidized cellulose, for example, the pH may be adjusted to alkaline conditions of 10 or higher, and at least a portion of the carboxy groups may be converted into a salt form (-COO - X + :X + refers to cations such as sodium, potassium, and lithium). Furthermore, the method for producing oxidized cellulose may further comprise the step of mixing the obtained oxidized cellulose with a compound having a modifying group. The compound having a modifying group is not particularly limited as long as it has a modifying group capable of forming an ionic or covalent bond with a carboxyl group or hydroxyl group in the oxidized cellulose, and examples thereof include the above-mentioned metal soaps, amines, and quaternary ammonium salt compounds. As described above, oxidized cellulose includes salt forms, proton forms, and forms modified with modifying groups. Nanocellulose obtained from this oxidized cellulose also includes salt forms, proton forms, and forms modified with modifying groups.

[0056] (Process B: Fiber defibration) The nanocellulose of the present invention can be obtained by defibrating the oxidized cellulose obtained above into nanoparticles. Methods for defibrating oxidized cellulose include weak stirring using a magnetic stirrer or the like, and mechanical defibration. Mechanical defibration of oxidized cellulose is preferred because it allows for sufficient defibration of oxidized cellulose and can shorten the defibration time. Here, nanocellulose (also called nanocellulose) is a general term for cellulose that has been nanosized, and includes cellulose nanofibers, cellulose nanocrystals, etc.

[0057] Examples of mechanical defibration methods include methods using various mixing and stirring devices such as a screw mixer, paddle mixer, disperser mixer, turbine mixer, homomixer under high-speed rotation, high-pressure homogenizer, ultra-high-pressure homogenizer, double-cylinder homogenizer, ultrasonic homogenizer, water-flow opposing collision-type disperser, beater, disk refiner, conical refiner, double-disc refiner, grinder, single-shaft or multi-shaft kneader, planetary stirrer, vibration stirrer, etc. Nanocellulose can be produced by treating oxidized cellulose with one of these devices alone or in combination of two or more types, preferably in a dispersion medium, to nanosize the oxidized cellulose.

[0058] The defibration of oxidized cellulose can be preferably performed using an ultra-high-pressure homogenizer, as this method allows for the production of nanocellulose with a more advanced defibration process. When using an ultra-high-pressure homogenizer, the pressure during the defibration process is preferably 100 MPa or higher, more preferably 120 MPa or higher, and even more preferably 150 MPa or higher. The number of defibration processes is not particularly limited, but from the viewpoint of sufficiently progressing defibration, it is preferably two or more times, more preferably three or more times. Furthermore, the oxidized cellulose can be sufficiently defibrated by mild stirring using a planetary stirrer or a vibration stirrer. Examples of vibration stirrers include a vortex mixer (touch mixer). In other words, when using the oxidized cellulose, uniform nanocellulose can be obtained even when the defibration process is performed under mild defibration conditions.

[0059] The defibration treatment is preferably carried out in a state where the oxidized cellulose is mixed with a dispersion medium. There are no particular restrictions on the dispersion medium, and it can be selected appropriately depending on the purpose. Specific examples of dispersion mediums include water, alcohols, ethers, ketones, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide. As the solvent, one of these may be used alone, or two or more may be used in combination.

[0060] Among the dispersion media, examples of alcohols include methanol, ethanol, isopropanol, isobutanol, sec-butyl alcohol, tert-butyl alcohol, methyl cellosolve, ethylene glycol, and glycerin. Examples of ethers include ethylene glycol dimethyl ether, 1,4-dioxane, and tetrahydrofuran. Examples of ketones include acetone and methyl ethyl ketone.

[0061] Using an organic solvent as a dispersion medium during the defibration process facilitates the isolation of oxidized cellulose and the nanocellulose obtained by defibrating it. Furthermore, because nanocellulose is obtained dispersed in an organic solvent, it can be easily mixed with resins that dissolve in organic solvents and their raw material monomers. Nanocellulose dispersions, in which the nanocellulose obtained by defibration is dispersed in a dispersion medium of water and / or organic solvent, can be used for mixing with various components such as resins, rubbers, and solid particles.

[0062] [Polymer of ethylenically unsaturated monomers] The type of ethylenically unsaturated monomer used in the present invention is not particularly limited and can be selected depending on the desired particle properties, the type of resin to be modified, etc. An ethylenically unsaturated monomer is a compound having at least one ethylene group. The ethylenically unsaturated monomer may be used alone or in combination of two or more types. A polymer of an ethylenically unsaturated monomer is a reaction product obtained by polymerizing an ethylenically unsaturated monomer.

[0063] Specific examples of the ethylenically unsaturated monomer include (meth)acrylic acid, alkyl (meth)acrylate, alkylene glycol (meth)acrylate, (meth)acrylonitrile, vinyl halide, maleic acid imide, phenylmaleimide, (meth)acrylamide, styrene, α-methylstyrene, vinyl acetate, etc. Among these, at least one selected from the group consisting of alkyl (meth)acrylate and styrene is preferred.

[0064] Examples of alkyl (meth)acrylates include those in which the number of carbon atoms in the alkyl portion is 1 to 10. The alkyl portion may be linear, branched, or cyclic, and may be unsubstituted or may have a substituent.

[0065] The ethylenically unsaturated monomer may have a functional group such as a carboxyl group, a hydroxyl group, an epoxy group, an amino group, an amide group, or a cyano group. Having these functional groups enhances affinity for cellulose nanofibers. On the other hand, from the viewpoint of avoiding difficulty in emulsification or dispersion and unstable polymerization, the proportion of the ethylenically unsaturated monomer having these functional groups is not particularly limited, but may be 5 mol % or less, 3 mol % or less, or 1 mol % or less of the total ethylenically unsaturated monomers.

[0066] The polymer of an ethylenically unsaturated monomer in the present invention may have a functional group. The polymer having a functional group may be prepared by introducing the functional group into the polymer by polymerizing the above-mentioned ethylenically unsaturated monomer having the functional group, or by introducing the functional group into a polymer of an ethylenically unsaturated monomer such as vinyl acetate.

[0067] The weight-average molecular weight of the polymer of the ethylenically unsaturated monomer is not particularly limited. For example, it may be 5,000 to 3,000,000. When the weight-average molecular weight of the particulate polymer is 5,000 or more, a decrease in the strength of the resin is suppressed, and when the weight-average molecular weight of the particles is 3,000,000 or less, the particles tend to melt easily in the resin, resulting in a sufficient modification effect.

[0068] Specifically, the weight average molecular weight (Mw) of the polymer of the ethylenically unsaturated monomer can be measured by the following method. The weight-average molecular weight of the polymer of the ethylenically unsaturated monomer is measured using GPC (gel permeation chromatography, for example, HLC-8220, manufactured by Tosoh Corporation). Specifically, an appropriate solvent is added to a resin composition containing nanocellulose and a polymer of the ethylenically unsaturated monomer to dissolve the polymer. The mixture is then filtered using a 0.45 μm filter, and the resulting liquid is measured in terms of polystyrene.

[0069] From the viewpoint of improving impact resistance, the ethylenically unsaturated monomer preferably contains a rubber component, such as a rubber-modified styrene-based resin. Rubber-modified styrene-based resins are typically obtained by polymerizing or copolymerizing (hereinafter sometimes referred to as "co)polymerization") a monomer mixture containing a styrene-based monomer and, if necessary, a vinyl monomer copolymerizable therewith (i.e., a monomer other than the above-mentioned styrene-based monomer) in the presence of a rubbery polymer, using a method such as bulk polymerization, bulk suspension polymerization, solution polymerization, precipitation polymerization, or emulsion polymerization. The rubber-modified styrene-based resin may be either a graft (co)polymer in which a (co)polymer containing a styrene-based monomer is grafted onto a rubbery polymer, or a non-graft (co)polymer in which a (co)polymer containing a styrene-based monomer is not grafted onto a rubbery polymer.

[0070] Specific examples of rubber-modified styrene resins include impact-resistant polystyrene, ABS resin (acrylonitrile-butadiene rubber-styrene copolymer), AAS resin (acrylonitrile-acrylic rubber-styrene copolymer), MBS resin (methyl methacrylate-butadiene rubber-styrene copolymer), and AES resin (acrylonitrile-ethylene propylene rubber-styrene copolymer), etc. These may be contained alone or in combination of two or more.

[0071] The rubber-modified styrene-based resin preferably contains 5 to 100 parts by weight of a graft (co)polymer obtained by graft polymerizing 95 to 20% by weight of a monomer mixture of a styrene-based monomer and other copolymerizable vinyl-based monomers to 5 to 80% by weight of a rubber polymer, and 0 to 95 parts by weight of a styrene-based (co)polymer obtained by polymerizing a monomer mixture of a styrene-based monomer and other copolymerizable vinyl-based monomers. The rubbery polymer is preferably a rubbery polymer having a glass transition temperature of 0°C or lower. Examples of rubbery polymers include diene rubbers such as polybutadiene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, styrene-butadiene block copolymer, butyl acrylate-butadiene copolymer, etc., acrylic rubbers such as polybutyl acrylate, polyisoprene, ethylene-olefin copolymer, ethylene-unsaturated carboxylic acid ester copolymer, ethylene-fatty acid vinyl copolymer, and ethylene-propylene-diene terpolymer. These may be used alone or in combination of two or more. Among these, polybutadiene or butadiene copolymer is preferred.

[0072] Examples of styrene-based monomers include styrene and styrene substituted with an alkyl group having 1 to 4 carbon atoms. Examples of styrene-based monomers substituted with an alkyl group having 1 to 4 carbon atoms include α-methylstyrene, p-methylstyrene, m-methylstyrene, o-methylstyrene, p-ethylstyrene, m-ethylstyrene, o-ethylstyrene, and t-butylstyrene.

[0073] The rubber-modified styrene-based resin may contain a monomer other than a styrene-based monomer. As the monomer other than a styrene-based monomer, a vinyl cyanide-based monomer is preferably used from the viewpoint of improving the impact resistance, chemical resistance, and plating property of the resin. Furthermore, a (meth)acrylic acid ester-based monomer is preferably used from the viewpoint of improving the toughness and color tone of the resin. Examples of the vinyl cyanide-based monomer include acrylonitrile, methacrylonitrile, and ethacrylonitrile, with acrylonitrile being preferred among these. Examples of the (meth)acrylic acid ester-based monomer include methyl, ethyl, propyl, n-butyl, and isobutyl esters of acrylic acid and methacrylic acid, with methyl methacrylate being preferred among these. If necessary, other vinyl monomers, for example, aromatic vinyl monomers other than styrene monomers such as vinyltoluene, and maleimide monomers such as maleimide, N-methylmaleimide, and N-phenylmaleimide, can also be used.

[0074] The monomer or monomer mixture used in the above-mentioned graft (co)polymer preferably contains 5 to 90% by mass, more preferably 10 to 80% by mass, of a styrene-based monomer, from the viewpoint of improving the impact resistance of the resin composition. When a vinyl cyanide-based monomer is mixed, the vinyl cyanide-based monomer is preferably contained in an amount of 1 to 50% by mass, more preferably 40% by mass or less, from the viewpoint of moldability of the resin composition. When plating adhesion is particularly required, a vinyl cyanide-based monomer in the range of 25 to 40% by mass is preferably used because it can improve catalyst adsorption ability in the catalyst step during plating treatment. Furthermore, when a (meth)acrylic acid ester-based monomer is mixed, the (meth)acrylic acid ester-based monomer is preferably contained in an amount of 80% by mass or less, more preferably 75% by mass or less, from the viewpoint of toughness and impact resistance. The total amount of the aromatic vinyl monomer, vinyl cyanide monomer, and (meth)acrylic acid ester monomer in the monomer or monomer mixture is preferably 95 to 20% by mass, and more preferably 90 to 30% by mass.

[0075] The blending ratio of the rubber polymer and the monomer mixture when obtaining the graft (co)polymer is preferably 5% by mass or more, more preferably 10% by mass or more, of the total graft (co)polymer (100% by mass) in terms of the impact resistance of the resin composition. Furthermore, from the viewpoint of the impact resistance of the resin composition and the appearance of the molded article, it is preferably 80% by mass or less, more preferably 70% by mass or less. Furthermore, the blending ratio of the monomer or monomer mixture is preferably 95% by mass or less, more preferably 90% by mass or less, or preferably 20% by mass or more, more preferably 30% by mass or more.

[0076] The graft (co)polymer can be obtained by a known polymerization method, for example, by emulsion polymerization in which a mixture of monomers and a chain transfer agent and a solution of a radical generator dissolved in an emulsifier are continuously fed into a polymerization vessel in the presence of a rubber polymer latex.

[0077] The graft (co)polymer may contain a non-grafted (co)polymer in addition to a graft (co)polymer having a structure in which a monomer or a monomer mixture is grafted onto a rubbery polymer. The graft ratio of the graft (co)polymer is not particularly limited, but is usually 20 to 80%, and may be in the range of 25 to 50%. Here, the graft ratio is a value calculated by the following formula: Graft ratio (%) = [<amount of vinyl copolymer grafted onto rubber polymer> / <rubber content of graft copolymer>] x 100

[0078] The properties of the ungrafted (co)polymer are not particularly limited, but a preferable condition for obtaining a resin composition with excellent impact resistance is that the intrinsic viscosity [η] (measured at 30°C) of the methyl ethyl ketone soluble matter is in the range of 0.25 to 1.00 dL / g, particularly 0.25 to 0.80 dL / g.

[0079] A styrene copolymer obtained by copolymerizing a maleimide monomer, i.e., a maleimide group-modified styrene copolymer, can be preferably used because the heat resistance of the resin composition can be improved and the flame retardancy can be specifically improved by incorporating it into a polystyrene resin.

[0080] The proportion of the styrene monomer, which is a constituent of the styrene (co)polymer, is preferably 5 to 90% by mass, more preferably 10 to 80% by mass, based on the total monomer content, from the viewpoint of impact resistance of the resin composition. When a vinyl cyanide monomer is mixed, the proportion is preferably 1 to 50% by mass, more preferably 40% by mass or less, from the viewpoint of impact resistance and fluidity. When plating adhesion is particularly required, a proportion of 25 to 40% by mass is preferably used, as this can improve catalyst adsorption capacity in the catalyst step during plating treatment. Furthermore, when a (meth)acrylic acid ester monomer is mixed, the proportion is preferably 80% by mass or less, more preferably 75% by mass or less, from the viewpoint of toughness and impact resistance. Furthermore, when other vinyl monomers copolymerizable therewith are mixed, the proportion is preferably 60% by mass or less, particularly preferably 50% by mass or less.

[0081] There are no limitations on the properties of the styrene-based (co)polymer, but those having an intrinsic viscosity [η] measured at 30°C using methyl ethyl ketone solvent in the range of 0.25 to 5.00 dL / g, particularly 0.35 to 3.00 dL / g, are preferred, as they provide resin compositions with excellent impact resistance and moldability.

[0082] There are no particular limitations on the method for producing the styrene-based (co)polymer, and conventional methods such as bulk polymerization, suspension polymerization, emulsion polymerization, solution polymerization, bulk-suspension polymerization, and solution-bulk polymerization can be used.

[0083] In the present invention, polyvinyl alcohol can also be used as the polymer of an ethylenically unsaturated monomer. In this specification, polyvinyl alcohol refers to a polymer obtained by saponifying a polyvinyl ester obtained by polymerizing a vinyl ester, which is an ethylenically unsaturated monomer. Examples of vinyl esters include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, and vinyl versatate. Among these, vinyl acetate is preferred.

[0084] When polymerizing a vinyl ester, other copolymerizable monomers can be copolymerized as needed within the scope of the invention. Examples of such monomers copolymerizable with vinyl esters include olefins having 2 to 30 carbon atoms, such as ethylene, propylene, 1-butene, and isobutene; acrylic acid and its salts; acrylic acid esters, such as methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, and octadecyl acrylate; methacrylic acid and its salts; methyl methacrylate, methacrylic acid, and the like. Methacrylic acid esters such as ethyl acrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, and octadecyl methacrylate; acrylamide, N-methylacrylamide, N-ethylacrylamide, N,N-dimethylacrylamide, diacetone acrylamide, acrylamidopropyldimethylamine and its salts, and N-methylolacrylamide and its derivatives. methacrylamide derivatives such as methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidopropyldimethylamine and its salts, and N-methylolmethacrylamide and its derivatives; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, and stearyl vinyl ether; nitriles such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride, and vinylidene fluoride; allyl compounds such as allyl acetate and allyl chloride; maleic acid and its salts or esters; itaconic acid and its salts or esters; vinylsilyl compounds such as vinyltrimethoxysilane; isopropenyl acetate; dihydroxybutene derivatives; vinyl ethyl carbonate; 3,4-diacetoxy-1-butene; and 3,4-diethoxy-1-butene.The copolymerization ratio of these copolymerizable monomers is preferably 15 mol% or less, more preferably 10 mol% or less. The lower limit is preferably 0.01 mol% or more, more preferably 0.05 mol% or more. The polyvinyl alcohol may also be modified in other ways. Examples of modified polyvinyl alcohol include polyvinyl acetal resins, which are obtained by acetalizing polyvinyl alcohol. Specific examples of polyvinyl acetal resins include polyvinyl formal, polyvinyl acetoacetal, polyvinyl propylal, and polyvinyl butyral.

[0085] The lower limit of the saponification degree of polyvinyl alcohol is preferably 70 mol%, more preferably 80 mol%, and the upper limit of the saponification degree of polyvinyl alcohol may be 100 mol% or less, or may be 99.8 mol% or less. The lower limit of the degree of polymerization of polyvinyl alcohol is preferably 500, more preferably 1,000. The upper limit of the degree of polymerization of polyvinyl alcohol is preferably 8,000, more preferably 4,000. By using polyvinyl alcohol having a degree of saponification and a degree of polymerization within the above ranges, sufficient strength tends to be imparted. The degree of saponification is a value measured in accordance with the test method JIS-K-6726:1994. The degree of polymerization (Po) is a value measured in accordance with the test method JIS-K-6726:1994, and is a value calculated by the following formula from the intrinsic viscosity [η] (dl / g) measured in water at 30°C after resaponifying and purifying polyvinyl alcohol. Po = ([η] × 103 / 8.29)(1 / 0.62)

[0086] The polyvinyl alcohol may be commercially available, such as Kuraray Poval (registered trademark), Exeval (registered trademark), ELVANOL (registered trademark), and Mobiflex (registered trademark) from Kuraray Co., Ltd., and Gohsenol (registered trademark), Gohsenex (registered trademark), and Nichigo G-Polymer (registered trademark) from Mitsubishi Chemical Corporation. Examples of polyvinyl acetal resins that can be used are S-LETS (registered trademark) from Sekisui Chemical Co., Ltd. and VINYLEC (registered trademark) from JNC Corporation.

[0087] When the polymer of the ethylenically unsaturated monomer in the present invention contains polyvinyl alcohol, various additives such as plasticizers, surfactants, and crosslinking agents can be blended. Here, the plasticizer is preferably a polyhydric alcohol, such as ethylene glycol, glycerin, diglycerin, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and trimethylolpropane, and one or more of these can be used in combination. The content of the plasticizer is not particularly limited, and may be in the range of 1 to 30 parts by mass relative to the polyvinyl alcohol.

[0088] Examples of the surfactant include anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. Examples of the anionic surfactant include carboxylic acid surfactants such as potassium laurate, sulfate esters such as octyl sulfate, sulfonic acid surfactants such as dodecylbenzenesulfonate and sodium alkylbenzenesulfonate, polyoxyethylene lauryl ether phosphate monoethanolamine salt, octyl phosphate potassium salt, lauryl phosphate potassium salt, stearyl phosphate potassium salt, octyl ether phosphate potassium salt, dodecyl phosphate sodium salt, tetradecyl phosphate sodium salt, dioctyl phosphate sodium salt, trioctyl phosphate sodium salt, polyoxyethylene arylphenyl ether phosphate potassium salt, and polyoxyethylene arylphenyl ether phosphate amine salt. Examples of nonionic surfactants include alkyl ether surfactants such as polyoxyethylene oleyl ether and polyoxyethylene lauryl ether; alkyl phenyl ether surfactants such as polyoxyethylene octylphenyl ether; alkyl ester surfactants such as polyoxyethylene laurate; alkyl amine surfactants such as polyoxyethylene lauryl amino ether; alkyl amide surfactants such as polyoxyethylene lauric acid amide; polypropylene glycol ether surfactants such as polyoxyethylene polyoxypropylene ether; alkanolamide surfactants such as oleic acid diethanolamide; and allyl phenyl ether surfactants such as polyoxyalkylene allyl phenyl ether. Examples of cationic surfactants include amines such as laurylamine hydrochloride; quaternary ammonium salts such as lauryl trimethylammonium chloride; and pyridinium salts such as lauryl pyridinium chloride. Examples of amphoteric surfactants include N-alkyl-N,N-dimethylammonium betaine. One or more surfactants can be used in combination. The content of the surfactant is preferably 0.01 to 7 parts by mass, more preferably 0.02 to 5 parts by mass, based on the PVA.

[0089] The crosslinking agent is not particularly limited as long as it undergoes a crosslinking reaction with polyvinyl alcohol, and examples thereof include boric acid, calcium borate, cobalt borate, zinc borate, aluminum potassium borate, ammonium borate, cadmium borate, potassium borate, copper borate, lead borate, nickel borate, barium borate, bismuth borate, magnesium borate, manganese borate, lithium borate, borax, boron compounds such as kernite, inyoite, kotsite, suianite, and seiberite; and tripotassium citrate. Among these, boron compounds are preferred, and boric acid and borax are more preferred. The content of the crosslinking agent is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, relative to the polyvinyl alcohol.

[0090] <Method of manufacturing resin composition> The resin composition of the present invention can be produced, for example, by a production method including a step of polymerizing an ethylenically unsaturated monomer in the presence of nanocellulose. Here, the nanocellulose used in this production method is an oxide of a cellulose-based raw material with hypochlorous acid or a salt thereof, is substantially free of N-oxyl compounds, and is selected from the following (I) and / or (II): (I) Zeta potential is less than -30 mV; (II) The light transmittance of a liquid mixture of nanocellulose and water at a solids concentration of 0.1% by mass is 95% or more. Details of the nanocellulose here are the same as those of the nanocellulose described above in [Nanocellulose].

[0091] The method for polymerizing the ethylenically unsaturated monomer in the presence of nanocellulose is not particularly limited. From the viewpoint of efficiently obtaining a resin composition, emulsion polymerization, suspension polymerization, or Pickering emulsion polymerization is preferred. Furthermore, after the polymerization reaction, the nanocellulose and the polymer of the ethylenically unsaturated monomer can be recovered by precipitation by adding a metal soap, an amine, a quaternary ammonium, etc. Therefore, the production method of the present invention may include a step of adding a metal soap, an amine, or a quaternary ammonium after the polymerization reaction to cause precipitation. Furthermore, the resin composition of the present invention can also be produced by a production method including a step of polymerizing an ethylenically unsaturated monomer in the presence of nanocellulose that has been reacted in advance with a metal soap, an amine, or a quaternary ammonium. These modify at least a portion of the nanocellulose with a metal soap, amine, or quaternary ammonium.

[0092] One method for polymerizing an ethylenically unsaturated monomer in the presence of nanocellulose by emulsion polymerization or suspension polymerization is to disperse cellulose nanofibers and an ethylenically unsaturated monomer in a solvent such as water, and heat the mixture in the presence of a polymerization initiator.

[0093] One embodiment of the polymer of an ethylenically unsaturated monomer contained in the resin composition of the present invention preferably includes a rubber-modified styrene-based resin, and more preferably an ABS resin. For example, among the rubber-modified styrene-based resins, ABS resin can be taken as an example. ABS resin can be produced by a blending method in which a rubbery polymer and an AS resin are mechanically mixed, a grafting method in which an ethylenically unsaturated monomer is polymerized in the presence of a rubbery polymer, or a graft-blending method in which a polymer obtained by the grafting method is mixed with an AS resin. These methods can be applied to the production method of the present invention. That is, when producing a resin composition containing ABS resin in the production method of the present invention, it can be produced by a blending method in which a rubbery polymer, nanocellulose, and an AS resin are mechanically mixed, a grafting method in which an ethylenically unsaturated monomer is polymerized in the presence of a rubbery polymer and nanocellulose, or a graft-blending method in which a polymer obtained by the grafting method is mixed with nanocellulose and an AS resin. Examples of the rubbery polymer include those similar to those described above in the "Polymer of an Ethylenically Unsaturated Monomer" section.

[0094] As the polymerization initiator used for polymerizing the ethylenically unsaturated monomer, a general polymerization initiator such as a persulfate, an organic peroxide, or an azo compound can be used. However, a persulfate is preferred in view of excellent polymerization reaction rate and productivity, and ammonium persulfate is more preferred in view of excellent water resistance of the obtained resin.

[0095] Examples of persulfates include ammonium persulfate, potassium persulfate, and sodium persulfate.

[0096] Examples of organic peroxides include t-butyl hydroperoxide, cumene hydroperoxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, di-i-propyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, t-butyl peroxypivalate, 2,2-bis(4,4-di-t-butylperoxycyclohexyl)propane, 2,2-bis(4,4-di-t-amylperoxycyclohexyl)propane, 2,2-bis(4,4-di-t-octylperoxycyclohexyl)propane, 2,2-bis(4,4-di-α-cumylperoxycyclohexyl)propane, 2,2-bis(4,4-di-t-butylperoxycyclohexyl)butane, and 2,2-bis(4,4-di-t-octylperoxycyclohexyl)butane.

[0097] Examples of the azo compound include 2,2'-azobis-2,4-dimethylvaleronitrile, 2,2'-azobis-i-butylnitrile, and 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile.

[0098] The persulfates and peroxides may be combined with reducing agents such as sodium hydrogen sulfite and sodium ascorbate to form redox polymerization initiators. The reducing agent may be appropriately selected depending on the type of persulfate or peroxide, and other reducing agents such as glucose and pyrophosphate may also be used. Furthermore, a chain transfer agent such as dodecanethiol may be used during the polymerization reaction.

[0099] The temperature during the polymerization reaction is not particularly limited, but is preferably in the range of 30°C to 180°C, and more preferably in the range of 50°C to 150°C, for example.

[0100] The ratio of nanocellulose to ethylenically unsaturated monomer when polymerizing the ethylenically unsaturated monomer in the presence of nanocellulose is not particularly limited. For example, the amount of ethylenically unsaturated monomer per 100 parts by mass of nanocellulose may be 5 to 1,000 parts by mass, or 10 to 100 parts by mass.

[0101] The polymer and nanocellulose obtained by the polymerization reaction can be recovered by appropriate post-treatment to obtain a resin composition. The post-treatment method is not particularly limited as long as it can recover the resin composition. Furthermore, as described above, the polymer and nanocellulose, or the nanocellulose and ethylenically unsaturated monomer, may be recovered by precipitation by adding metal soap, amine, quaternary ammonium, or the like. The solvent used in the polymerization reaction of the ethylenically unsaturated monomer may or may not be removed. The product obtained by the polymerization reaction may be filtered and washed to form a resin composition. Furthermore, the resin composition obtained by the above method may be dispersed in another solvent after removing the solvent used in the polymerization reaction, and the solvent may be further removed by distillation, filtration, or the like.

[0102] The resin composition obtained by the above method may be used as it is, or may be molded into a desired shape (powder, beads, pellets, etc.).

[0103] The resin composition of the present invention can also be obtained by blending oxidized cellulose obtained by oxidizing a cellulosic raw material with hypochlorous acid or a salt thereof with a resin raw material, and then appropriately defibrating and nano-sizing the oxidized cellulose to form a composite of nanocellulose and a polymer of an ethylenically unsaturated monomer. Furthermore, the resin composition of the present invention can be produced by appropriately defibrating and nano-sizing the oxidized cellulose obtained by oxidizing a cellulosic raw material with hypochlorous acid or a salt thereof, and then using the oxidized cellulose for the production of a resin composition. As described above, the resin composition of the present invention can be produced using oxidized cellulose obtained by oxidizing a cellulosic raw material with hypochlorous acid or a salt thereof.

[0104] One of the manufacturing methods of the present invention is a method for manufacturing a resin composition containing nanocellulose and a polymer of an ethylenically unsaturated monomer, which includes the steps of: stirring a first mixture containing oxidized cellulose and an ethylenically unsaturated monomer to obtain a second mixture containing nanocellulose and a polymer of the ethylenically unsaturated monomer; and polymerizing the ethylenically unsaturated monomer using the second mixture, wherein the oxidized cellulose comprises an oxide of a cellulosic raw material with hypochlorous acid or a salt thereof. One of the manufacturing methods of the present invention is a method for manufacturing a resin composition containing nanocellulose and a polymer of an ethylenically unsaturated monomer, which includes the steps of: stirring oxidized cellulose and continuously adding an ethylenically unsaturated monomer to obtain a mixture containing the nanocellulose and the ethylenically unsaturated monomer; and polymerizing the ethylenically unsaturated monomer using the mixture, wherein the oxidized cellulose comprises an oxide of a cellulosic raw material with hypochlorous acid or a salt thereof. The polymerization method here is not particularly limited, but is preferably emulsion polymerization or suspension polymerization. The specific polymerization method and conditions are the same as those in the method for producing a resin composition using nanocellulose described above.

[0105] One of the manufacturing methods of the present invention is a method for manufacturing a resin composition containing nanocellulose and a polymer of an ethylenically unsaturated monomer, which method includes a step of obtaining a resin composition containing nanocellulose and a polymer of an ethylenically unsaturated monomer by stirring a first mixture containing oxidized cellulose and a polymer of an ethylenically unsaturated monomer, wherein the oxidized cellulose comprises an oxide of a cellulosic raw material with hypochlorous acid or a salt thereof. One of the manufacturing methods of the present invention is a method for manufacturing a resin composition containing nanocellulose and a polymer of an ethylenically unsaturated monomer, which method includes a step of stirring oxidized cellulose and continuously adding a polymer of an ethylenically unsaturated monomer to obtain a resin composition containing the nanocellulose and the polymer of an ethylenically unsaturated monomer, wherein the oxidized cellulose comprises an oxide of a cellulosic raw material with hypochlorous acid or a salt thereof.

[0106] The oxidized cellulose used in the production method of the present invention may be any of the oxidized cellulose forms described above in [Nanocellulose], but specifically, it is preferable that it is substantially free of N-oxyl compounds. Furthermore, the degree of polymerization of the oxidized cellulose used in the production method of the present invention is preferably 600 or less. The definition of "substantially free of N-oxyl compounds," the definition of the degree of polymerization of oxidized cellulose, and preferred embodiments thereof are as described above in [Nanocellulose]. The nanocellulose in the resin composition obtained by the method for producing a resin composition of the present invention may be in the form of nanocellulose described above in [Nanocellulose]. In the present invention, "continuously adding an ethylenically unsaturated monomer or a polymer of an ethylenically unsaturated monomer" means that the pulverization of at least a portion of the oxidized cellulose by stirring and the addition of the blend are carried out in succession. Specific embodiments in which the stirring and the addition of the blend are carried out in succession include, but are not limited to, an embodiment in which the pulverization of oxidized cellulose by stirring and the addition of the ethylenically unsaturated monomer or a polymer of an ethylenically unsaturated monomer are carried out in a one-pot operation; an embodiment in which the ethylenically unsaturated monomer or a polymer of an ethylenically unsaturated monomer is added simultaneously with stirring of the oxidized cellulose; etc. The embodiments of the ethylenically unsaturated monomer or its polymer used in the production method of the present invention are as described above in [Polymer of Ethylenically Unsaturated Monomer]. Furthermore, when the resin composition of the present invention contains a rubber-modified styrene-based resin, the above-mentioned blending method, grafting method, and graft-blending method can be applied to production methods using oxidized cellulose. That is, when producing a resin composition containing an ABS resin, among other rubber-modified styrene-based resins, the resin can be produced by, for example, a blending method in which a rubber polymer, oxidized cellulose, and AS resin are mechanically mixed; a grafting method in which a mixture of a rubber polymer, an ethylenically unsaturated monomer, and oxidized cellulose is stirred to defibrate at least a portion of the oxidized cellulose, followed by polymerization; or a graft-blending method in which the polymer obtained by the grafting method, oxidized cellulose, and AS resin are stirred to defibrate at least a portion of the oxidized cellulose and then mixed.

[0107] In the production method of the present invention, when stirring oxidized cellulose to at least partially pulverize it, there are no particular limitations as long as the operation disperses the components that make up the nanocellulose-containing composition, and for example, velocity fields and velocity fluctuations of any intensity; collisions with inclusions or obstacles; ultrasound; pressure loading; etc. can be used. A submerged disperser can be suitably used for such dispersion operations. Therefore, in one embodiment of the production method of the present invention, stirring is performed using a submerged disperser. The submerged disperser is not particularly limited, and examples thereof include methods using a homomixer, a magnetic stirrer, a stirring rod, a stirrer with stirring blades, a disperser-type mixer, a homogenizer, an external circulation stirrer, a planetary stirrer, a vibration stirrer, an ultrasonic disperser, etc. In addition to the above-mentioned devices, examples of the submerged disperser include a rotary shear type stirrer, a colloid mill, a roll mill, a pressure homogenizer, a container-driven mill, a media stirring mill, etc. Furthermore, a kneader can be used as the submerged disperser. A rotary shear mixer is a device that disperses materials by passing them through the gap between the rotor and the outer cylinder, and disperses them by shear flow in the gap and strong speed fluctuations back and forth. A colloid mill is a device that disperses particles by shear flow in the gap between a rotating disk and a fixed disk, while a roll mill disperses particles by shear and compression forces that utilize the gap between multiple rotating rolls. A pressure homogenizer is used as a disperser that ejects a slurry or the like from fine holes at high pressure, and is also called a pressure injection disperser. A preferred pressure homogenizer is a high-pressure homogenizer. A high-pressure homogenizer is a homogenizer capable of ejecting a slurry at a pressure of, for example, 10 MPa or more, preferably 100 MPa or more. Examples of high-pressure homogenizers include counter-impingement high-pressure homogenizers such as microfluidizers and wet jet mills. Vessel-driven mills are devices that disperse materials by the collision and friction of media such as balls in a vessel, and specific examples include rotary mills, vibration mills, and planetary mills. Media-agitated mills are devices that use media such as balls or beads to disperse materials by the impact and shear forces of the media, and specific examples include attritors and bead mills (sand mills). A kneader is a device used to wet powders and other materials with a liquid (also known as kneading or kneading).Specific examples include twin-arm kneaders (devices that disperse materials using two mixing blades inside two semi-cylindrical containers); Banbury mixers (devices that disperse materials under pressure in a closed system); and extrusion-type kneaders such as screw extruders, co-kneaders, and extruders. These devices may be used alone or in combination of two or more. Although stirring using such an apparatus can promote the refinement of oxidized cellulose, stirring may be continued until the components of the nanocellulose-containing composition are homogenized or emulsified, which allows the nanocellulose to be uniformly dispersed in the nanocellulose-containing composition and also allows the nanocellulose-containing composition to be obtained as an emulsion.

[0108] The resin composition containing nanocellulose and a polymer of an ethylenically unsaturated monomer obtained by a production method using oxidized cellulose can be recovered by appropriate post-treatment to obtain a resin composition. The post-treatment method is not particularly limited as long as it allows the recovery of the resin composition, and may be recovered by precipitation by adding a metal soap, amine, quaternary ammonium, or the like to a mixture of nanocellulose and a polymer of an ethylenically unsaturated monomer. The solvent used in the polymerization reaction of the ethylenically unsaturated monomer may or may not be removed. The resulting product may also be filtered and washed to obtain a resin composition.

[0109] <Resin> The resin of the present invention may be obtained by using the resin composition of the present invention as it is, or by mixing the resin modifier with a resin (also referred to as a raw resin) to be blended. The resin of the present invention contains at least the resin composition of the present invention.

[0110] The type of raw material resin is not particularly limited, and examples thereof include moldable resins such as thermoplastic resins and thermoplastic elastomers. Examples of the thermoplastic resin include rubber-modified styrene-based resin, acrylic resin, polyolefin, polyester, polyurethane, polystyrene, polyamide, polyvinyl chloride, polycarbonate, etc. The rubber-modified styrene-based resin is the same as that described above. Examples of the thermoplastic elastomer include olefin elastomers, styrene elastomers, polyamide elastomers, polyester elastomers, and polyurethane elastomers.

[0111] The raw resin may contain the same components as those contained in the resin modifier, or segments or functional groups that have good affinity with the resin modifier. In particular, if the same components as those contained in the resin modifier or segments that have good affinity are formed into a polymer alloy structure, effects such as impact absorption are imparted, which is preferable. If the affinity between the resin modifier and the resin to be mixed is poor, the dispersibility of the resulting resin may decrease, resulting in a deterioration in the appearance of the resin, or a decrease in the breaking stress and breaking elongation.

[0112] The amount of resin modifier contained in the resin of the present invention is not particularly limited, and may be, for example, 0.1 to 10 parts by mass of resin modifier per 100 parts by mass of resin.

[0113] <Polyvinyl alcohol film> When the resin composition of the present invention contains polyvinyl alcohol, a polyvinyl alcohol film can be produced from the composition. The polyvinyl alcohol film of the present invention can also be called a polyvinyl alcohol sheet. Examples of films include packaging films, optical polarizing films, retardation films, agricultural material films (films for keeping vegetables warm and for growing vegetables), water-soluble films (water transfer films, packaging films for pesticides, detergents, etc.), and oxygen barrier films. The thickness of the film may be adjusted depending on the purpose and use, and is usually in the range of 5 to 1000 μm.

[0114] The film can be obtained using a solution containing the resin composition of the present invention by a casting method, a solution coating method, a wet film-forming method (a method in which the film is discharged into a poor solvent), a gel film-forming method (a method in which an aqueous PVA polymer solution is cooled to gel, and then the solvent is extracted and removed), a method based on a combination of these, a melt extrusion film-forming method in which a composition containing a plasticizer is melted, etc. Among these, films obtained by the casting method, the solution coating method, and the melt extrusion film-forming method are preferred.

[0115] The film thus obtained can be stretched uniaxially or biaxially before or after the drying step, if necessary. Stretching can be performed using a device such as a pressure press. Stretching conditions are preferably a temperature of 20 to 120°C and a stretch ratio of 1.05 to 5 times, more preferably 1.1 to 3 times. Furthermore, if necessary, the film can be heat-set after stretching to reduce residual stress.

[0116] The polyvinyl alcohol film of the present invention may be appropriately processed and formed into a desired shape. [Example]

[0117] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the following, unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass".

[0118] [Production Example 1: Production of nanocellulose] 350 g of sodium hypochlorite pentahydrate crystals with an available chlorine concentration of 42% by mass were placed in a beaker, and pure water was added and stirred to adjust the available chlorine concentration to 21% by mass. 35% by mass of hydrochloric acid was added and stirred to make an aqueous solution with a pH of 11. The aqueous sodium hypochlorite solution was heated to 30°C in a constant temperature water bath while being stirred at 200 rpm using a propeller-type stirring blade in a Shinto Scientific mixer (Three-One Motor, BL600), and then 50 g of powdered cellulose (KC Flock W-100GK) manufactured by Nippon Paper Industries Co., Ltd., a cellulose-based raw material, was added. After supplying the cellulosic raw material, the mixture was kept at 30°C in the same thermostatic water bath, and the pH during the reaction was adjusted to 11 by adding 48% by mass of sodium hydroxide. The reaction was then stirred under the same conditions with a stirrer for 30 minutes. After the reaction was completed, the product was subjected to solid-liquid separation by suction filtration using a PVDF mesh filter with 45 μm openings, and the resulting oxidized cellulose was washed with pure water. Pure water was added to oxidized cellulose to prepare a 5% dispersion, which was then processed 14 times at 200 MPa using a Sugino Machine ultra-high pressure homogenizer called Starburst Lab to obtain a nanocellulose aqueous dispersion. In the ultra-high pressure homogenizer, the oxidized cellulose aqueous dispersion was circulated through the built-in ultra-high pressure defibrating section to promote defibration. One pass of the liquid through the defibrating section is called one pass. The residual nitrogen components derived from N-oxyl compounds in the CNF were measured as nitrogen content using a trace total nitrogen analyzer (manufactured by Mitsubishi Chemical Analytech Co., Ltd., device name: TN-2100H), and the increase from the raw pulp was calculated, resulting in a value of less than 1 ppm.

[0119] The available chlorine concentration in the aqueous sodium hypochlorite solution was measured by the following method. (Measurement of available chlorine concentration in sodium hypochlorite solution) 0.582 g of an aqueous solution of sodium hypochlorite pentahydrate crystals in pure water was precisely weighed, 50 ml of pure water was added, 2 g of potassium iodide and 10 ml of acetic acid were added, and the bottle was immediately sealed and left in a dark place for 15 minutes. After leaving it for 15 minutes, the liberated iodine was titrated with 0.1 mol / L sodium thiosulfate solution (indicator: starch TS), and the titer was found to be 34.55 ml. A blank test was performed separately to correct for this, and since 1 ml of 0.1 mol / L sodium thiosulfate solution corresponds to 3.545 mg Cl, the available chlorine concentration in the sodium hypochlorite aqueous solution was found to be 21% by mass.

[0120] The amount of carboxy groups in the oxidized cellulose was measured by the following method. (Measurement of Carboxy Group Amount) To 60 ml of an oxidized cellulose aqueous dispersion, in which the oxidized cellulose concentration had been adjusted to 0.5% by mass, 0.1 M aqueous hydrochloric acid was added to adjust the pH to 2.5, and then 0.05 N aqueous sodium hydroxide solution was added dropwise and the electrical conductivity was measured until the pH reached 11.0. The amount of carboxyl groups (mmol / g) was calculated using the following formula from the amount of sodium hydroxide (a) consumed in the neutralization stage of the weak acid, in which the change in electrical conductivity was gradual. Amount of carboxyl group = a (ml) x 0.05 / mass of oxidized cellulose (g)

[0121] [Production Example 2] The same procedure as in Production Example 1 was carried out, except that the reaction time was changed to 2 hours.

[0122] [Measurement of average fiber length and average fiber width] Pure water was added to the aqueous nanocellulose dispersion obtained above to adjust the nanocellulose concentration in the CNF aqueous dispersion to 5 ppm. After adjusting the concentration, the CNF aqueous dispersion was allowed to air dry on a mica substrate, and the shape of the nanocellulose was observed using an Oxford Asylum MFP-3D Infinity scanning probe microscope in AC mode. The obtained images were binarized using the image processing software "ImageJ" and analyzed for fiber length. For 100 or more fibers, the number-average fiber length was calculated as fiber length = "perimeter" ÷ 2. The average fiber width was calculated using the software provided with the MFP-3D infinity for 50 or more fibers, with the number average fiber width [nm] calculated as the cross-sectional height of the shape image = fiber width.

[0123] [Zeta potential measurement] The aqueous dispersion of nanocellulose obtained above was diluted with pure water to a nanocellulose concentration of 0.1%. After dilution, a 0.05 mol / L aqueous solution of sodium hydroxide was added to the aqueous dispersion of nanocellulose to adjust the pH to 8.0, and the zeta potential was measured at 20°C using a zeta potential meter (ELSZ-1000) manufactured by Otsuka Electronics Co., Ltd.

[0124] [Light transmittance measurement] The aqueous dispersion of nanocellulose obtained above was placed in a 10 mm thick quartz cell, and the light transmittance at a wavelength of 660 nm was measured using a spectrophotometer (JASCO V-550).

[0125] [Measurement of Viscosity Average Degree of Polymerization] Oxidized cellulose was added to an aqueous solution of sodium borohydride adjusted to pH 10 and reduced at 25°C for 5 hours. The amount of sodium borohydride was 0.1 g per 1 g of oxidized cellulose. After reduction, solid-liquid separation was performed by suction filtration, followed by washing with water. The resulting oxidized cellulose was freeze-dried. 0.04 g of dried oxidized cellulose was added to 10 ml of purified water and stirred for 2 minutes. 10 ml of 1 M copper ethylenediamine solution was then added to dissolve the oxidized cellulose. The flow times of the blank solution and the cellulose solution were then measured at 25°C using a capillary viscometer. The relative viscosity (ηr), specific viscosity (ηsp), and intrinsic viscosity (η) were calculated sequentially from the flow times of the blank solution (t0), the flow time of the cellulose solution (t), and the oxidized cellulose concentration (c [g / ml]) using the following equations. The degree of polymerization (DP) of the oxidized cellulose was then calculated using the following viscometric equation. ηr=η / η0=t / t0 ηsp=ηr-1 [η]=ηsp / (100×c(1+0.28ηsp)) DP=175×[η]

[0126] The physical properties of the nanocellulose of Production Example 1, the nanocellulose of Production Example 2, and the CNF (LEOCRYSTA (registered trademark) I-2SX, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) used in Comparative Example 1 are shown in Table 1. The CNF of Comparative Example 1 is CNF obtained by micronization through TEMPO oxidation.

[0127] [Table 1]

[0128] [Example 1] To 100.0 g of the aqueous dispersion containing nanocellulose from Production Example 1 (nanocellulose concentration 1.3% by mass), 0.94 g of 0.5 M hydrochloric acid was added and stirred to convert the carboxyl groups of the nanocellulose to the acid form. Ethylenically unsaturated monomers, styrene (also referred to as St) and acrylonitrile (also referred to as AN), were added and dispersed ultrasonically. Then, 0.091 g of monododecylamine (also referred to as MDA) (containing 5 g of ethanol; the same applies below) was added and stirred. The reactor was heated to 70 °C under a nitrogen atmosphere, and ammonium persulfate (APS) was added as a polymerization initiator. Polymerization was carried out by heating for 4 hours. After the polymerization was completed, post-treatment such as heat drying was carried out to obtain a resin composition (resin modifier) containing the nanocellulose of Production Example 1 and a polymer of an ethylenically unsaturated monomer.

[0129] [Example 2] 3.93 g of styrene, 1.68 g of acrylonitrile, and 0.35 g of a 1% by mass aqueous solution of ammonium persulfate were added to 100 g of the nanocellulose dispersion (nanocellulose concentration 1.3% by mass) from Production Example 2. After ultrasonic dispersion, the mixture was placed in a nitrogen atmosphere and heated at 70°C for 4 hours while stirring to polymerize. After the polymerization was completed, 1.40 g of 0.5 M hydrochloric acid was added to the reaction solution and filtered, and then 0.32 g of a 40% aqueous solution of tetrabutylammonium hydroxide (also referred to as TBAH) was added and stirred to precipitate the nanocellulose and resin microparticles of Production Example 1. This was filtered and subjected to post-treatment such as washing to obtain a resin composition (resin modifier) containing nanocellulose of Production Example 2 and a polymer of an ethylenically unsaturated monomer.

[0130] [Comparative Example 1] The same procedure as in Example 1 was carried out, except that a commercially available CNF (Leocrysta (registered trademark) I-2SX, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) (nanocellulose concentration: 2% by mass) was used as the nanocellulose.

[0131] <Strength evaluation> The resin modifiers obtained in Examples 1 and 2 and Comparative Example 1 were added to a moldable ABS resin (manufactured by Techno UMG Co., Ltd., product number ABS130) in an amount of 0.5 to 2 mass% (in nanocellulose equivalent) of the total. Specifically, the resin modifier and ABS resin pellets were mixed in a cup, and then heated and kneaded using a plastomill. The kneading temperature was 160°C, and the kneading time was 9 minutes. The mixture was then pressed at 180°C for 2 minutes using a press to form a flat plate. The pressure was 10 MPa for the first minute and 15 MPa for the next minute. Using the resulting flat plate-shaped mixture, a No. 3 dumbbell (1 mm thick) test piece was prepared according to JIS K 6251:2010. Similarly, test pieces were prepared using ABS resin without the resin modifier.

[0132] [Three-point bending test] A three-point bending test was performed using the test specimens. Specifically, the bending test (test speed: 5 mm / min, distance between supports: 30 mm) specified in JIS K 7171:2016 was performed using the test specimens, and the flexural modulus (MPa), breaking stress (MPa), and breaking strain (%) were measured. The results of the breaking strain and breaking stress are shown in Figure 1. In Figure 1, resins with the resin modifier (nanocellulose content) of Example 1 at 0.5 mass%, 1.0 mass%, and 2 mass% are shown as Examples 3, 4, and 5, respectively. In addition, the resin modifier of Comparative Example 1 (2.0 mass% nanocellulose equivalent) is shown as Comparative Example 2.

[0133] [Charpy impact test] The test piece was used to carry out a Charpy impact test (notch tip radius: rN = 0.25 mm) specified in JIS K 7111-1:2012, and the impact strength (kJ / m 2 ) was measured.

[0134] Table 2 shows the evaluation results of the flexural modulus and impact strength (Charpy impact).

[0135] [Table 2]

[0136] [Production Example 3: Production of oxidized cellulose] 350 g of sodium hypochlorite pentahydrate crystals with an effective chlorine concentration of 42% by mass were placed in a beaker, and pure water was added and stirred to adjust the effective chlorine concentration to 21% by mass. 35% by mass of hydrochloric acid was added thereto and stirred to obtain a sodium hypochlorite aqueous solution with a pH of 11. The above sodium hypochlorite aqueous solution was heated to 30°C in a constant temperature water bath while being stirred at 200 rpm using a propeller-type stirring blade in a Shinto Scientific mixer (Three-One Motor, BL600), and then 50 g of powdered pulp (VP-1) from TDI was added as a cellulosic raw material. After supplying the cellulosic raw material, the mixture was kept at 30°C in the same thermostatic water bath, and the pH during the reaction was adjusted to 11 by adding 48% by mass of sodium hydroxide, followed by stirring under the same conditions for 2 hours using a stirrer. After the reaction was completed, centrifugation (1000 G, 10 minutes), decantation, and addition of pure water in an amount equivalent to the removed liquid were repeated to recover oxidized cellulose (solid concentration 13%). Here, the solid content concentration was calculated from the mass of the dried product obtained by drying the oxidized cellulose at 110°C for 2 hours using the formula (mass of dried product / mass of oxidized cellulose)×100.

[0137] The physical properties of the oxidized cellulose of Production Example 3 are shown in Table 3.

[0138] [Table 3]

[0139] [Example 6] 15.6 g of the oxidized cellulose from Production Example 3 (13% solids) was added to 800 g of water and defibrated using a Primix TK Robomix at 10,000 rpm for 10 minutes. 203.9 g of the oxidized cellulose was then collected and transferred to a flask. A portion was removed and the oxidized cellulose from Production Example 3 was confirmed to have been defibrated into nanocellulose using the measurements described above. Specifically, the nanocellulose had an optical transmittance of 95.03%, a zeta potential of -42.3 mV, an average fiber length of 200 nm, and an average fiber width of 3 nm. To this mixture, 27.8 g of polybutadiene latex (concentration 54%), 67 g of styrene (St), 19 g of acrylonitrile (AN), 0.41 g of dodecanethiol, and 1.3 g of cumene hydroperoxide were added and dispersed using a TK Robomix at 10,000 rpm for 5 minutes. The reactor was heated to 70°C while nitrogen was blown into it at 100 mL / min. After 1 hour, an aqueous solution of 1.7 g of glucose and 8.1 g of water and an aqueous solution of 0.86 g of pyrophosphoric acid and 4.0 g of water were added, and the mixture was allowed to polymerize for 3 hours. After the polymerization was completed, the reaction solution was cooled to room temperature, and a solution of 0.33 g of monododecylamine and 30 g of methanol was added to precipitate the polymer and nanocellulose. The precipitate was filtered, washed with water, and dried to obtain a composite A-1 of nanocellulose and ABS resin.

[0140] [Example 7] 800 g of water was added to 15.6 g of the oxidized cellulose of Production Example 3 (13% solids), and the mixture was defibrated using a Primix TK Robomix at 10,000 rpm for 10 minutes, yielding 203.9 g of nanocellulose dispersion. A portion was removed and the measurements described above confirmed that the oxidized cellulose of Production Example 3 had been defibrated to form nanocellulose. Specifically, the nanocellulose had a light transmittance of 95.03%, a zeta potential of -42.3 mV, an average fiber length of 200 nm, and an average fiber width of 3 nm. Meanwhile, 200 g of water was added to a reactor, and 2.5 g of sodium lauryl sulfate, 27.8 g of polybutadiene latex (concentration 54%), 67 g of styrene (St), 19 g of acrylonitrile (AN), 0.41 g of dodecanethiol, and 1.3 g of cumene hydroperoxide were added thereto, and the mixture was dispersed at 10,000 rpm with TK Robomix for 5 minutes. The reactor was heated to 70°C while nitrogen was blown into it at 100 mL / min. After 1 hour, an aqueous solution of 1.7 g of glucose and 8.1 g of water, and an aqueous solution of 0.86 g of pyrophosphate and 4.0 g of water were added. The mixture was allowed to polymerize for 3 hours, after which the entire 203.9 g of the defibrated nanocellulose dispersion described above was added. Sodium chloride and a solution of 0.33 g of monododecylamine and 30 g of methanol were added to this to precipitate the polymer and nanocellulose. The reaction solution was heated at 95°C for 0.5 hours, then cooled, filtered, washed with water, and dried to obtain Complex B-1.

[0141] [Example 8] 31.0 g of oxidized cellulose (13% solids) from Production Example 3 was added to 784 g of water and stirred until homogenous. 206.5 g of the oxidized cellulose was then transferred to a flask. 27.8 g of polybutadiene latex (54% concentration), 67 g of styrene (St), 19 g of acrylonitrile (AN), 0.41 g of dodecanethiol, and 1.3 g of cumene hydroperoxide were added and dispersed for 5 minutes at 10,000 rpm using a TK Robomix. Defibration of the oxidized cellulose from Production Example 3 into nanocellulose was confirmed by adding 31.0 g of oxidized cellulose (13% solids) from Production Example 3 to 784 g of water and dispersing for 5 minutes at 10,000 rpm using a TK Robomix. The nanocellulose had an optical transmittance of 95.03%, a zeta potential of -42.3 mV, an average fiber length of 200 nm, and an average fiber width of 3 nm. The vessel was heated to 70°C while nitrogen was blown into it at 100 mL / min. After 1 hour, an aqueous solution of 1.7 g of glucose and 8.1 g of water and an aqueous solution of 0.86 g of pyrophosphate and 4.0 g of water were added, and the mixture was allowed to polymerize for 3 hours. After the polymerization was completed, the reaction solution was cooled to room temperature, and a solution of 0.33 g of monododecylamine and 30 g of methanol was added to precipitate the polymer and nanocellulose. The precipitate was then filtered, washed with water, and dried to obtain a composite of nanocellulose and ABS resin C-1.

[0142] [Example 9] The same procedure as in Example 8 was carried out according to Table 4 to obtain a composite D-1 of nanocellulose and ABS resin. In Example 9, in the process of precipitating the polymer and nanocellulose, an isopropanol solution of magnesium stearate was used instead of a methanol solution of monododecylamine.

[0143] [Example 10] The same procedure as in Example 8 was carried out according to Table 4 to obtain a composite E-1 of nanocellulose and ABS resin.

[0144] Comparative Example 3 200 g of water was added to a reactor, and 2.5 g of sodium lauryl sulfate, 27.8 g of polybutadiene latex (concentration 54%), 67 g of styrene (St), 19 g of acrylonitrile (AN), 0.41 g of dodecanethiol, and 1.3 g of cumene hydroperoxide were added thereto, and the mixture was dispersed using TK Robomix at 10,000 rpm for 10 minutes. The reactor was heated to 70°C while nitrogen was blown into it at 100 mL / min. After 1 hour, an aqueous solution of 1.7 g of glucose and 8.1 g of water and an aqueous solution of 0.86 g of pyrophosphoric acid and 4.0 g of water were added, and the mixture was allowed to polymerize for 3 hours. Sodium chloride was added to this to precipitate the polymer, which was then heated at 95°C for 0.5 hours, cooled, filtered, washed with water and dried to obtain ABS resin F-1.

[0145] The composites A-1 to E-1 and the ABS resin F-1 were pressed at 180°C for 2 minutes using a press to form a flat plate. The pressure was 10 MPa for the first minute and 15 MPa for the next minute. Test pieces in the shape of a No. 3 dumbbell (1 mm thick) as specified in JIS K6251:2010 were prepared using the obtained flat kneaded material. A three-point bending test was performed according to the method described above, and the flexural modulus (MPa) and flexural strength (MPa) were measured. Charpy impact was also measured according to the method described above. The results are shown in Table 4.

[0146] [Table 4]

[0147] [Example 11] 2.85 g of the oxidized cellulose of Production Example 3 (solids content: 13% by mass) was added to 180 g of water and dispersed uniformly at 10,000 rpm for 10 minutes using a TK Robomix to prepare a 0.2% by mass aqueous nanocellulose dispersion. A portion was removed and the measurements described above confirmed that the oxidized cellulose of Production Example 3 had been defibrated to form nanocellulose. The nanocellulose had a light transmittance of 95.03%, a zeta potential of -42.3 mV, an average fiber length of 200 nm, and an average fiber width of 3 nm. Separately, 5 g of PVA28-98 (saponification degree 98%, polymerization degree 1700) manufactured by Kuraray was added to 95 g of water and dissolved using a mix rotor at 100 rpm for 5 hours to prepare a 5% by mass aqueous solution of polyvinyl alcohol. 26.3 g of 0.2 mass% nanocellulose aqueous dispersion (0.0526 g as solids) and 20 g of 5 mass% polyvinyl alcohol aqueous solution (1.0 g as solids) were mixed and then mixed at 100 rpm for 5 hours using a mix rotor to obtain film-forming solution A. This film-forming solution A was cast onto a glass plate covered with a PET film at room temperature to a thickness of 200 μm after drying. The film was then placed in a vacuum dryer and heated and dried at 40°C under normal pressure for 1 day, then dried under reduced pressure at 40°C for 1 day at 0.1 kPa. After that, a flat plate heating and pressing press was used to pressurize the film at 150°C for 2 minutes at 1 MPa, then at 150°C for 2 minutes at 3 MPa, and finally at 25°C for 2 minutes at 3 MPa to obtain PVA sheet G-1, which contains 5% nanocellulose by mass in polyvinyl alcohol. The resulting flat PVA sheet was cut into 5 mm wide and 80 mm long specimens. A tensile test was carried out according to the method described above, and the tensile modulus (MPa) was measured to be 1050 MPa. The appearance was also excellent, with no turbidity or foreign matter visible to the naked eye. The results are shown in Table 5.

[0148] [Example 12] PVA sheet H-1 was obtained in the same manner as in Example 11, except that the amount of 0.2% by mass nanocellulose aqueous dispersion used in Example 11 was changed to 5.05 g (0.0101 g as solids) so that 1% by mass of nanocellulose was contained in the polyvinyl alcohol. A tensile test was performed according to the method described above, and the tensile modulus (MPa) was measured, which was 320 MPa. Furthermore, the appearance was excellent in transparency, with no turbidity or foreign matter visible to the naked eye. The results are shown in Table 5.

[0149] [Example 13] A sheet was obtained in the same manner as in Example 11, except that polyvinyl butyral resin (S-LEC BM-1, manufactured by Sekisui Chemical Co., Ltd.) was used instead of Kuraray PVA28-98, the water used to dissolve it was isopropanol, and a 5 mass % isopropanol solution of polyvinyl butyral resin was used. The sheet of Example 13 had excellent transparency, with no turbidity or foreign matter visible to the naked eye.

[0150] Comparative Example 5 PVA sheet I-1 containing 1% by mass of nanocellulose in polyvinyl alcohol was obtained in the same manner as in Example 12, except that commercially available CNF (Leocrysta (registered trademark) I-2SX, manufactured by Dai-ichi Kogyo Seiyaku) was used as the nanocellulose. A tensile test was conducted according to the method described above, and the tensile modulus (MPa) was measured to be 260 MPa. In addition, the appearance was excellent in transparency, with no turbidity or foreign matter visible to the naked eye. The results are shown in Table 5.

[0151] Comparative Example 6 PVA sheet J-1 was obtained in the same manner as in Example 12, except that nanocellulose was not added. A tensile test was performed according to the method described above, and the tensile modulus (MPa) was measured to be 185 MPa. Furthermore, the appearance was excellent in transparency, with no turbidity or foreign matter visible to the naked eye. The results are shown in Table 5.

[0152] [Example 14] A PVA sheet K-1 containing 1% by mass of nanocellulose in polyvinyl alcohol was obtained in the same manner as in Example 12, except that when dissolving Kuraray PVA28-98 in water, the oxidized cellulose from Production Example 3 was added and then dispersed using a TK Robomix at 10,000 rpm for 10 minutes. A tensile test was conducted according to the method described above, and the tensile modulus (MPa) was measured, finding it to be 375 MPa. Furthermore, the appearance was excellent in transparency, with no visible turbidity or foreign matter. The results are shown in Table 5.

[0153] [Table 5]

[0154] [Production Example 4: Production of modified oxidized cellulose] To the oxidized cellulose of Production Example 3, 0.5 M hydrochloric acid was added with stirring to adjust the pH to 2, converting the carboxy groups of the oxidized cellulose to the acid form. Monododecylamine and isopropanol were then added to adjust the pH to 7, and modified oxidized cellulose (solids concentration 14%) was recovered. The type of oxidation, amount of carboxy groups, and degree of polymerization of the oxidized cellulose remained unchanged from the oxidized cellulose of Production Example 3.

[0155] [Example 15] A sheet was obtained in the same manner as in Example 11, except that the oxidized cellulose used was the modified oxidized cellulose of Production Example 4. The sheet of Example 15 had excellent transparency, with no visible turbidity or foreign matter.

[0156] The composition of the present invention has excellent elastic modulus and transparency when formed into a sheet, and is particularly useful as a film material. When formed into a film, it can be used for optical purposes such as polarizing plates, as well as for water-soluble or biodegradable films for hydraulic transfer printing, liquid packaging for liquid detergents and the like, powder packaging for pesticides and pharmaceuticals, and laundry bags for medical clothing. Furthermore, it can be formed into fibers, and can be used as paper processing agents, fiber processing agents, fiber sizing agents, paints, coating agents, adhesives, and the like. [Industrial Applicability]

[0157] The resin composition of the present invention can reinforce resins and has industrial applicability in the field of reinforced resins.

Claims

1. A resin composition comprising nanocellulose and a polymer of an ethylenically unsaturated monomer, The nanocellulose The oxidized cellulose is an oxide of a cellulose-based raw material using hypochlorous acid or a salt thereof, and is obtained by defibrating the oxidized cellulose, Substantially free of N-oxyl compounds, The following (I) and / or (II): (I) Zeta potential is −30 mV or less; (II) The light transmittance of a mixed solution obtained by mixing nanocellulose with water to a solids concentration of 0.1% by mass is 95% or more; A resin composition that satisfies the above requirements.

2. A resin composition comprising nanocellulose and a polymer of an ethylenically unsaturated monomer, The nanocellulose derived from oxidized cellulose and obtained by defibrating the oxidized cellulose; It has a structure in which the hydroxyl groups at the second and third positions of the glucopyranose ring are oxidized to introduce carboxyl groups, The following (I) and / or (II): (I) Zeta potential is −30 mV or less; (II) The light transmittance of a mixed solution obtained by mixing nanocellulose with water to a solids concentration of 0.1% by mass is 95% or more; A resin composition that satisfies the above requirements.

3. The zeta potential of the nanocellulose is -70 mV or more; The resin composition according to claim 1 or 2.

4. The amount of carboxyl groups in the nanocellulose is 0.30 mmol / g or more and less than 2.0 mmol / g, The resin composition according to any one of claims 1 to 3.

5. the nanocellulose is derived from oxidized cellulose; The degree of polymerization of the oxidized cellulose is 600 or less. The resin composition according to any one of claims 1 to 4.

6. The polymer of the ethylenically unsaturated monomer includes a rubber-modified styrene-based resin. The resin composition according to any one of claims 1 to 5.

7. The polymer of the ethylenically unsaturated monomer includes polyvinyl alcohol. The resin composition according to any one of claims 1 to 5.

8. The amount of the polymer of the ethylenically unsaturated monomer relative to 100 parts by mass of the nanocellulose is 5 parts by mass or more and 1000 parts by mass or less, The resin composition according to any one of claims 1 to 7.

9. At least a portion of the nanocellulose is modified with a metal soap, an amine, or a quaternary ammonium; The resin composition according to any one of claims 1 to 8.

10. A method for producing a resin composition, comprising a step of polymerizing an ethylenically unsaturated monomer in the presence of nanocellulose, The nanocellulose The oxidized cellulose is an oxide of a cellulose-based raw material using hypochlorous acid or a salt thereof, and is obtained by defibrating the oxidized cellulose, Substantially free of N-oxyl compounds, The following (I) and / or (II): (I) Zeta potential is −30 mV or less; (II) The light transmittance of a mixed solution obtained by mixing nanocellulose with water to a solids concentration of 0.1% by mass is 95% or more; Manufacturing method that meets the above requirements.

11. A method for producing a resin composition, comprising a step of polymerizing an ethylenically unsaturated monomer in the presence of nanocellulose, The nanocellulose derived from oxidized cellulose and obtained by defibrating the oxidized cellulose; It has a structure in which the hydroxyl groups at the second and third positions of the glucopyranose ring are oxidized to introduce carboxyl groups, The following (I) and / or (II): (I) Zeta potential is −30 mV or less; (II) The light transmittance of a mixed solution obtained by mixing nanocellulose with water to a solids concentration of 0.1% by mass is 95% or more; Manufacturing method that meets the above requirements.

12. The polymerization method is emulsion polymerization or suspension polymerization. The method according to claim 10 or 11.

13. A method for producing a resin composition containing nanocellulose and a polymer of an ethylenically unsaturated monomer, A step of agitating a first mixture containing oxidized cellulose and an ethylenically unsaturated monomer to obtain a second mixture containing nanocellulose and an ethylenically unsaturated monomer; and polymerizing an ethylenically unsaturated monomer using the second mixture, the oxidized cellulose comprises an oxidation product of a cellulosic raw material with hypochlorous acid or a salt thereof; The nanocellulose The following (I) and / or (II): (I) Zeta potential is −30 mV or less; (II) The light transmittance of a mixed solution obtained by mixing nanocellulose with water to a solids concentration of 0.1% by mass is 95% or more; Manufacturing method that meets the above requirements.

14. A method for producing a resin composition containing nanocellulose and a polymer of an ethylenically unsaturated monomer, A step of stirring the oxidized cellulose and continuously adding an ethylenically unsaturated monomer to obtain a mixture comprising nanocellulose and an ethylenically unsaturated monomer; and polymerizing an ethylenically unsaturated monomer using the mixture, the oxidized cellulose comprises an oxidation product of a cellulosic raw material with hypochlorous acid or a salt thereof; The nanocellulose The following (I) and / or (II): (I) Zeta potential is −30 mV or less; (II) The light transmittance of a mixed solution obtained by mixing nanocellulose with water to a solids concentration of 0.1% by mass is 95% or more; Manufacturing method that meets the above requirements.

15. A method for producing a resin composition containing nanocellulose and a polymer of an ethylenically unsaturated monomer, A step of agitating a first mixture containing oxidized cellulose and an ethylenically unsaturated monomer to obtain a second mixture containing nanocellulose and an ethylenically unsaturated monomer; and polymerizing an ethylenically unsaturated monomer using the second mixture, the oxidized cellulose has a structure in which the hydroxyl groups at the second and third positions of the glucopyranose ring have been oxidized and carboxyl groups have been introduced, The nanocellulose The following (I) and / or (II): (I) Zeta potential is −30 mV or less; (II) The light transmittance of a mixed solution obtained by mixing nanocellulose with water to a solids concentration of 0.1% by mass is 95% or more; Manufacturing method that meets the above requirements.

16. A method for producing a resin composition containing nanocellulose and a polymer of an ethylenically unsaturated monomer, A step of stirring the oxidized cellulose and continuously adding an ethylenically unsaturated monomer to obtain a mixture comprising nanocellulose and an ethylenically unsaturated monomer; and polymerizing an ethylenically unsaturated monomer using the mixture, the oxidized cellulose has a structure in which the hydroxyl groups at the second and third positions of the glucopyranose ring have been oxidized and carboxyl groups have been introduced, The nanocellulose The following (I) and / or (II): (I) Zeta potential is −30 mV or less; (II) The light transmittance of a mixed solution obtained by mixing nanocellulose with water to a solids concentration of 0.1% by mass is 95% or more; Manufacturing method that meets the above requirements.

17. The polymerization method is emulsion polymerization or suspension polymerization. The method according to any one of claims 13 to 16.

18. A method for producing a resin composition containing nanocellulose and a polymer of an ethylenically unsaturated monomer, The method includes a step of obtaining a resin composition containing nanocellulose and a polymer of an ethylenically unsaturated monomer by stirring a first mixture containing oxidized cellulose and a polymer of an ethylenically unsaturated monomer, the oxidized cellulose comprises an oxidation product of a cellulosic raw material with hypochlorous acid or a salt thereof; The nanocellulose The following (I) and / or (II): (I) Zeta potential is −30 mV or less; (II) The light transmittance of a mixed solution obtained by mixing nanocellulose with water to a solids concentration of 0.1% by mass is 95% or more; Manufacturing method that meets the above requirements.

19. A method for producing a resin composition containing nanocellulose and a polymer of an ethylenically unsaturated monomer, The method includes a step of stirring the oxidized cellulose and continuously adding a polymer of an ethylenically unsaturated monomer to obtain a resin composition containing the nanocellulose and the polymer of an ethylenically unsaturated monomer, the oxidized cellulose comprises an oxidation product of a cellulosic raw material with hypochlorous acid or a salt thereof; The nanocellulose The following (I) and / or (II): (I) Zeta potential is −30 mV or less; (II) The light transmittance of a mixed solution obtained by mixing nanocellulose with water to a solids concentration of 0.1% by mass is 95% or more; Manufacturing method that meets the above requirements.

20. A method for producing a resin composition containing nanocellulose and a polymer of an ethylenically unsaturated monomer, The method includes a step of obtaining a resin composition containing nanocellulose and a polymer of an ethylenically unsaturated monomer by stirring a first mixture containing oxidized cellulose and a polymer of an ethylenically unsaturated monomer, the oxidized cellulose has a structure in which the hydroxyl groups at the second and third positions of the glucopyranose ring have been oxidized and carboxyl groups have been introduced, The nanocellulose The following (I) and / or (II): (I) Zeta potential is −30 mV or less; (II) The light transmittance of a mixed solution obtained by mixing nanocellulose with water to a solids concentration of 0.1% by mass is 95% or more; Manufacturing method that meets the above requirements.

21. A method for producing a resin composition containing nanocellulose and a polymer of an ethylenically unsaturated monomer, The method includes a step of stirring the oxidized cellulose and continuously adding a polymer of an ethylenically unsaturated monomer to obtain a resin composition containing the nanocellulose and the polymer of an ethylenically unsaturated monomer, the oxidized cellulose has a structure in which the hydroxyl groups at the second and third positions of the glucopyranose ring have been oxidized and carboxyl groups have been introduced, The nanocellulose The following (I) and / or (II): (I) Zeta potential is −30 mV or less; (II) The light transmittance of a mixed solution obtained by mixing nanocellulose with water to a solids concentration of 0.1% by mass is 95% or more; Manufacturing method that meets the above requirements.

22. The method further comprises precipitating the nanocellulose and polymer of ethylenically unsaturated monomers by adding a metal soap, an amine, or a quaternary ammonium; The method according to any one of claims 18 to 21.

23. A resin comprising the resin composition according to any one of claims 1 to 9.

24. A polyvinyl alcohol film produced from the resin composition according to claim 7.

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