JP2020007495A - Cellulose-containing resin composition - Google Patents

Abstract

To provide a resin composition that achieves an excellent fibrillation state in a resin, expresses excellent mechanical characteristics of CNF, and renders the whole system acidic in the resin composition, so that the peeling reaction of cellulose is inhibited, and the coloring and odors due to cellulose are reduced.SOLUTION: A polyamide resin composition contains (A) a polyamide with an amino group terminal concentration [-NH] and a carboxyl group terminal concentration [-COOH] satisfying the following formula (1): [-NH]<[-COOH] (1) and (B) a cellulose fiber with an average fiber diameter of 500 nm or less.SELECTED DRAWING: None

Description

  The present invention relates to a resin composition containing cellulose.

Since thermoplastic resins are light and have excellent processing characteristics, they are widely used in various fields such as automobile parts, electric / electronic parts, office equipment housings, and precision parts. However, a resin alone often has insufficient mechanical properties, dimensional stability, and the like, and a composite of a resin and various inorganic materials is generally used.
A resin composition in which a thermoplastic resin is reinforced with a reinforcing material that is an inorganic filler such as glass fiber, carbon fiber, talc, or clay has a high specific gravity, and thus has a problem that the weight of the obtained resin molded article increases.

In recent years, cellulose has been used as a new reinforcing material for resins.
It is known that cellulose has, as its simple properties, a high elastic modulus comparable to aramid fiber and a lower linear expansion coefficient than glass fiber. Further, the true density is as low as 1.56 g / cm ^3, and glass (density 2.4 to 2.6 g / cm ³ ) or talc (density 2.7 g / cm ³ ) used as a reinforcing material for general thermoplastic resin is used. cm ³ ), which is by far the lightest material.

  Cellulose has a wide variety of sources, including those made from trees, hemp, cotton, kenaf, cassava and the like. Furthermore, bacterial cellulose such as Nata de coco is also known. These natural resources as raw materials are present in large quantities on the earth, and techniques for utilizing cellulose as a filler in resins have attracted attention for their effective use.

  Patent Literatures 1 to 4 disclose techniques for dispersing fine fibrous cellulose called cellulose nanofiber (hereinafter, sometimes referred to as CNF) in a thermoplastic resin.

  CNF is obtained by using a pulp or the like as a raw material, hydrolyzing a hemicellulose part to make it weak, and then defibrating it by a pulverization method such as a high-pressure homogenizer, a microfluidizer, a ball mill or a disc mill, and is obtained in water. It forms a high-level dispersion state and network called a nano-dispersion.

International Publication No. 2011/058678 International Publication No. WO 2016/199923 Japanese Patent Publication No. Hei 9-505329 JP 2008-001728 A

  In order to mix CNF in the resin, it is necessary to dry and powder CNF, but there is a problem that CNF becomes a strong aggregate from a finely dispersed state in the process of separation from water and is difficult to be redispersed. This cohesive force is expressed by hydrogen bonding due to the hydroxyl groups of cellulose, and is said to be very strong.

  Therefore, in order to exhibit sufficient performance, it is necessary to apply strong shearing or the like to the CNF and defibrate to a fiber diameter of nanometer size (that is, less than 1 μm). Further, even if the defibration itself can be sufficiently realized, it is difficult to maintain the defibrated state in the resin.

  On the other hand, it is known that cellulose, which is a constituent component of CNF, reacts with a reducing terminal group under basic conditions to release a sugar residue (peeling reaction). The released monosaccharide has poor heat stability and causes coloring. Moreover, this monosaccharide causes odor (sugar odor) in a closed space such as a room or a car. The detachment of the monosaccharide by the peeling reaction has a remarkable effect particularly on a large molding machine having a long residence time, and is a serious problem.

  The present invention suppresses the peeling reaction of cellulose by realizing a good defibration state in the resin and expressing the excellent mechanical properties of CNF, and further, making the entire system acidic in the resin composition. It is an object of the present invention to provide a resin composition having reduced coloring and odor caused by cellulose.

  The present inventors have conducted intensive studies to solve the above problems, and as a result, have found that a resin composition containing a polyamide resin containing a large amount of carboxyl group terminals and cellulose fibers can solve the above problems, and the present invention I've reached the point.

That is, the present invention includes the following embodiments.
[1] (A) The amino group terminal concentration [—NH ₂ ] and the carboxyl group terminal concentration [—COOH] are represented by the following formula (1):
[-NH ₂ ] <[-COOH] (1)
A polyamide that satisfies
(B) A polyamide resin composition containing cellulose fibers having an average fiber diameter of 500 nm or less.
[2] The polyamide resin composition according to the above aspect 1, further comprising 0.1 to 50 parts by mass of a dispersant based on 100 parts by mass of the cellulose fiber.
[3] The polyamide resin composition according to the above aspect 1 or 2, wherein the sum of the carboxyl group terminal concentration and the amino group terminal concentration ([-NH ₂ ] + [-COOH]) of the polyamide is 10 μmol / g or more. object.
[4] the sum of the carboxyl group terminal concentration and an amino group end concentration of the polyamide _{([-NH 2] + [-} COOH]) is not more than 500μ mol / g, according to any of the above embodiments 1 to 3 Polyamide resin composition.
[5] The polyamide resin composition according to any one of the above aspects 1 to 4, comprising 1 to 20 parts by mass of hemicellulose and / or 0.1 to 10 parts by mass of lignin with respect to 100 parts by mass of the cellulose fibers. .
[6] The polyamide resin composition according to any one of the above aspects 1 to 5, which is in the form of a resin pellet and has a moisture content of 1200 ppm or less.
[7] The polyamide according to any one of the above aspects 1 to 6, which is obtained by polymerizing a raw material monomer of a polyamide resin in the presence of a cellulose fiber having a water-containing average fiber diameter of 500 nm or less. Resin composition.
[8] A molded article formed from the polyamide resin composition according to any one of the above aspects 1 to 7.

  The resin composition of the present invention gives sufficient mechanical properties to the resin molded product, gives sufficient molding processability and color tone for practical use, and has an effect of low odor.

  Exemplary embodiments of the present invention will be specifically described below, but the present invention is not limited to these embodiments.

≪Polyamide≫
As the polyamide, various polyamides having a structure of aliphatic, aromatic, or a combination thereof can be used. Examples of preferable polyamides include polyamide 6, polyamide 11, and polyamide 12 obtained by a polycondensation reaction of lactams, 1,6-hexanediamine, 2-methyl-1,5-pentanediamine, and 1,7-heptanediamine. 2-methyl-1-6-hexanediamine, 1,8-octanediamine, 2-methyl-1,7-heptanediamine, 1,9-nonanediamine, 2-methyl-1,8-octanediamine, 1,10 Diamines such as decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, m-xylylenediamine, and butanedioic acid, pentanedioic acid, hexanedioic acid, heptanedioic acid, octaneedioic acid, nonane; Diacid, decandioic acid, benzene-1,2-dicarboxylic acid, benzene-1,3-dicarboxylic acid, benzene-1 Polyamide 6,6, polyamide 6,10, polyamide 6,11 obtained as a copolymer with dicarboxylic acids such as cyclohexane-1,3-dicarboxylic acid and cyclohexane-1,4-dicarboxylic acid such as 4-dicarboxylic acid; Polyamide 6,12, polyamide 6, T, polyamide 6, I, polyamide 9, T, polyamide 10, T, polyamide 2M5, T, polyamide MXD, 6, polyamide 6, C, polyamide 2M5, C, etc .; Copolymers such as copolymers (polyamide 6, T / 6, I, for example) copolymerized respectively are exemplified.

  Among these polyamides, aliphatic polyamides such as polyamide 6, polyamide 11, polyamide 12, polyamide 6,6, polyamide 6,10, polyamide 6,11 and polyamide 6,12 and fats such as polyamide 6, C and polyamide 2M5, C Cyclic polyamides are more preferred.

  As a method for adjusting the terminal group concentration of the polyamide, a known method can be used. For example, a diamine compound, a monoamine compound, a dicarboxylic acid compound, a monocarboxylic acid compound, an acid anhydride, a monoisocyanate, a monoacid halide, a monoester, a monoalcohol, etc., so as to have a predetermined terminal group concentration during polymerization of the polyamide. A method in which a terminal adjuster that reacts with a terminal group is added to the polymerization solution may be used.

  Examples of the terminal regulator that reacts with a terminal amino group include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, and isobutyric acid. Aliphatic monocarboxylic acids such as cyclohexanecarboxylic acid; aromatic monocarboxylic acids such as benzoic acid, toluic acid, α-naphthalenecarboxylic acid, β-naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, and phenylacetic acid; Carboxylic acid; adipic acid, suberic acid, azelaic acid, sebacic acid, dodecandioic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 5-sodium Sulfoisophthalic acid, hexahydroterephthalic acid, hexahi Dicarboxylic acids such as droisophthalic acid and diglycolic acid; and a plurality of mixtures arbitrarily selected from these. Among them, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid are preferred from the viewpoints of reactivity, sealed terminal stability, and price. And at least one terminal adjuster selected from the group consisting of benzoic acid, isophthalic acid, terephthalic acid and adipic acid.

Examples of a terminal adjuster that reacts with a terminal carboxyl group include aliphatic amines such as methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine, stearylamine, dimethylamine, diethylamine, dipropylamine, and dibutylamine. Monoamines; alicyclic monoamines such as cyclohexylamine and dicyclohexylamine; aromatic monoamines such as aniline, toluidine, diphenylamine and naphthylamine; tetramethylenediamine, hexamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylene Diamine, 2,2,4- / 2,4,4-trimethylhexamethylenediamine, 5-methylnonamethylenediamine, 2,4-dimethyloctamethyl Diamine, meta-xylylenediamine, para-xylylenediamine, 1,3-bis (aminomethyl) cyclohexane, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, 3,8-bis (aminomethyl) Tricyclodecane, bis (4-aminocyclohexyl) methane, bis (3-methyl-4-aminocyclohexyl) methane, 2,2-bis (4-aminocyclohexyl) propane, bis (aminopropyl) piperazine, aminoethylpiperazine, etc. And any mixtures thereof. Among them, 1 selected from the group consisting of butylamine, hexylamine, octylamine, decylamine, stearylamine, cyclohexylamine, aniline and hexamethylenediamine, from the viewpoints of reactivity, boiling point, stability of the sealed terminal, and price. More than one terminal regulator is preferred.
The method of adding the terminal adjuster to the composition and reacting with the terminal functional group is not particularly limited, but one embodiment is a method in which the terminal adjuster is added at an arbitrary ratio during the polymerization and reacted.

The concentration of these amino terminal groups and carboxyl terminal groups is preferably determined from the integrated value of the characteristic signal corresponding to each terminal group by ¹ H-NMR in terms of accuracy and simplicity. As a method for determining the concentration of these terminal groups, a method described in JP-A-7-228775 is specifically recommended. When this method is used, deuterated trifluoroacetic acid is useful as a measuring solvent. Further, the number of times of integration of ¹ H-NMR requires at least 300 scans even when measured by an instrument having a sufficient resolution. In addition, the concentration of the terminal group can be measured by a titration measurement method as described in JP-A-2003-055549. However, in order to minimize the influence of mixed additives, lubricants, and the like, quantification by ¹ H-NMR is more preferable.

  The terminal carboxyl group concentration of the polyamide resin usable in the present invention is not particularly limited, but the lower limit is preferably 20 μmol / g, and more preferably 30 μmol / g. The upper limit of the terminal carboxyl group concentration is preferably 150 μmol / g, more preferably 100 μmol / g, and still more preferably 80 μmol / g.

  Although the terminal amino group concentration of the polyamide resin usable in the present invention is not particularly limited, the lower limit is preferably 20 μmol / g, and more preferably 30 μmol / g. The upper limit of the terminal amino group concentration is preferably 150 μmol / g, more preferably 100 μmol / g, and further preferably 80 μmol / g.

  The total concentration of the terminal amino group and terminal carboxyl group of the polyamide resin usable in the present invention is not particularly limited, but since the thermal decomposition of the cellulose fiber starts from the attack on the main chain of the primary hydroxyl group, the primary hydroxyl group is It is preferable that the number of terminal amino groups and terminal carboxyl groups that can be stabilized by interaction be large. That is, the lower limit of the total concentration is preferably 10 μmol / g, more preferably 50 μmol / g, further preferably 100 μmol / g, and most preferably 135 μmol / g.

  When the viscosity of the resin is low, burrs are generated at the time of injection molding. Therefore, it is preferable that the polyamide has a large molecular weight. That is, the upper limit of the total concentration is preferably 500 μmol / g, more preferably 300 μmol / g, further preferably 135 μmol / g, and most preferably 100 μmol / g.

In the polyamide of this embodiment, the ratio of carboxyl end groups to amino end groups ([COOH] / [NH ₂ ]) is greater than one. The lower limit of the carboxyl terminal group ratio is preferably 1.01, more preferably 1.05, and most preferably 1.10. The upper limit of the carboxyl terminal group ratio is not particularly limited, but is preferably 10,000, more preferably 1,000, still more preferably 100, and most preferably 10. The carboxyl terminal group ratio is preferably greater than 1 from the viewpoint of suppressing the peeling reaction of the cellulose fiber, and is preferably 10,000 or less from the viewpoint of coloring the polyamide.

  The polyamide usable in the present invention preferably has an intrinsic viscosity [η] measured in concentrated sulfuric acid at 30 ° C. of 0.6 to 2.0 dL / g, and 0.7 to 1.4 dL / g. g, more preferably 0.7 to 1.2 dL / g, and particularly preferably 0.7 to 1.0 dL / g. Use of the polyamide having an intrinsic viscosity in a preferable range, and particularly preferable range among them, can significantly increase the fluidity in a mold at the time of injection molding of the resin composition, and give an effect of improving the appearance of a molded piece. it can.

  In the present invention, the “intrinsic viscosity” has the same meaning as a viscosity generally called an intrinsic viscosity. A specific method for obtaining this viscosity is to measure ηsp / c of several measurement solvents having different concentrations in 96% concentrated sulfuric acid under a temperature condition of 30 ° C., to determine the respective ηsp / c and the concentration (c ) And extrapolating the concentration to zero. The value extrapolated to zero is the intrinsic viscosity. Details of these are described in, for example, pages 291 to 294 of Polymer Process Engineering (Prentice-Hall, Inc. 1994). At this time, it is desirable from the viewpoint of accuracy that the number of the measurement solvents having different concentrations be at least four. At this time, the recommended concentrations of the different viscosity measurement solutions are preferably at least four points of 0.05 g / dL, 0.1 g / dL, 0.2 g / dL, and 0.4 g / dL.

≪Cellulose fiber≫
Next, the cellulose fibers that can be used in the present invention will be described in detail.

  Cellulose fiber in the present invention is treated with pulp or the like with hot water of 100 ° C. or more, hydrolyzes the hemicellulose portion to make it weak, and then is crushed by a high-pressure homogenizer, a microfluidizer, a ball mill, a disk mill, or a mixer. Refers to defibrated cellulose.

  The average L / D lower limit of the cellulose fiber is preferably 50, more preferably 80, more preferably 100, even more preferably 120, and most preferably 150. The upper limit is not particularly limited, but is preferably 5,000 or less from the viewpoint of handleability. The average L / D ratio of the cellulose fibers is desirably within the above range in order to exhibit a small amount of good mechanical properties of the resin molded article obtained by using the resin composition of the present disclosure.

  In the present disclosure, the length, diameter, and L / D ratio of each of the cellulose fibers are determined by using a water-dispersed liquid of each of the cellulose fibers with a high-shear homogenizer (eg, Nippon Seiki Co., Ltd., trade name “Excel Auto Homogenizer ED”). -7 "), processing conditions: an aqueous dispersion dispersed at a rotation speed of 15,000 rpm for 5 minutes, diluted with pure water to 0.1 to 0.5% by mass, cast on mica, and air-dried. The obtained sample is used as a measurement sample, which is measured and measured with a high-resolution scanning microscope (SEM) or an atomic force microscope (AFM). Specifically, the length (L) and diameter (D) of 100 randomly selected celluloses were measured in an observation field of view in which the magnification was adjusted so that at least 100 celluloses were observed, Calculate the ratio (L / D). For the cellulose fiber, the number average value of the length (L), the number average value of the diameter (D), and the number average value of the ratio (L / D) are calculated.

  Alternatively, the length, diameter, and L / D ratio of the cellulose fiber in the composition can be confirmed by measuring the solid composition as a measurement sample by the above-described measurement method.

  Alternatively, the length, diameter, and L / D ratio of the cellulose fiber in the composition are determined by dissolving the resin component in the composition in an organic or inorganic solvent capable of dissolving the resin component of the composition, separating cellulose, After sufficiently washing with the solvent, an aqueous dispersion in which the solvent was replaced with pure water was prepared, and the cellulose concentration was diluted with pure water to 0.1 to 0.5% by mass, cast on mica, and air-dried. This can be confirmed by measuring the sample as a measurement sample by the above-described measurement method. At this time, the measurement is performed on 100 or more randomly selected celluloses.

  As the cellulose fibers, those having an average fiber diameter of 500 nm or less are used. The average fiber diameter of the cellulose fiber that can be suitably used in the present invention is preferably 1 nm or more, more preferably 5 nm or more, still more preferably 10 nm or more, particularly preferably 15 nm or more, and most preferably. Is not less than 20 nm, preferably not more than 450 nm, more preferably not more than 400 nm, still more preferably not more than 350 nm, still more preferably not more than 300 nm, and most preferably not more than 250 nm. In order to effectively develop the mechanical properties, it is desirable that the diameter of the cellulose fiber be within the above range.

  The crystallinity of the cellulose fibers is preferably at least 55%. When the crystallinity is in this range, the mechanical properties (strength and dimensional stability) of the cellulose fiber itself are high, so when the cellulose fiber is dispersed in the resin, the strength and the dimensional stability of the resin composition tend to be high. is there. A more preferred lower limit of the crystallinity is 60%, still more preferably 70%, and most preferably 80%. The upper limit of the crystallinity of the cellulose fiber is not particularly limited, and is preferably higher, but the preferable upper limit is 99% from the viewpoint of production.

  In addition, when the residual amount of impurities such as lignin is large, discoloration may occur due to heat during processing, and from the viewpoint of suppressing discoloration of the resin composition during extrusion and molding, crystallization of cellulose fibers is also performed. The degree is desirably within the above range.

In the case where the cellulose fibers are cellulose type I crystals (derived from natural cellulose), the crystallinity here refers to the diffraction pattern (2θ / deg. Is 10 to 30) when the sample is measured by wide-angle X-ray diffraction. It is obtained by the following equation by the Segal method.
Crystallinity (%) = ([diffraction intensity due to (200) plane of 2θ / deg. = 22.5] − [diffraction intensity due to amorphousness of 2θ / deg. = 18]) / [2θ / Deg. = Diffraction intensity due to (200) plane of 22.5] x 100

When the cellulose fiber is a cellulose II crystal (derived from regenerated cellulose), the crystallinity is 2θ = 12.6 ° attributed to the (110) plane peak of the cellulose II crystal in wide-angle X-ray diffraction. And the peak intensity h1 from the baseline at this interplanar spacing are determined by the following equation.
Crystallinity (%) = h1 / h0 × 100

  As crystalline forms of cellulose, types I, II, III, and IV are known. Among them, types I and II are widely used, and types III and IV are obtained on a laboratory scale. Although it is used, it is not widely used on an industrial scale. As the cellulose fiber used in the present invention, the mobility of the structure is relatively high, by dispersing the cellulose fiber in the resin, the coefficient of linear expansion is lower, the tensile, the strength and elongation at the time of bending deformation was more excellent From the viewpoint of obtaining a resin composition, cellulose fibers containing cellulose type I crystals or cellulose type II crystals are preferable, and cellulose fibers containing cellulose type I crystals and having a crystallinity of 55% or more are more preferable.

  Further, the degree of polymerization of the cellulose fiber is preferably 400 or more, more preferably 420 or more, more preferably 430 or more, more preferably 440 or more, more preferably 450 or more, preferably 3500 or less, more preferably 3300 or less. Or less, more preferably 3200 or less, more preferably 3100 or less, more preferably 3000 or less.

  From the viewpoint of processability and development of mechanical properties, it is desirable that the degree of polymerization of the cellulose fiber be within the above range. From the viewpoint of processability, it is preferable that the degree of polymerization is not too high, and it is desired that the degree of polymerization is not too low from the viewpoint of developing mechanical properties.

  The degree of polymerization of the cellulose fiber means an average degree of polymerization measured according to the reduced specific viscosity method using a copper ethylenediamine solution described in the confirmation test (3) of the “Fifteenth Revised Japanese Pharmacopoeia Manual (issued by Hirokawa Shoten)”. .

  Examples of a method for controlling the degree of polymerization of cellulose fibers (that is, the average degree of polymerization) include a hydrolysis treatment and the like. By the hydrolysis treatment, the depolymerization of the amorphous cellulose inside the cellulose fiber proceeds, and the average degree of polymerization decreases. At the same time, the hydrolysis treatment removes impurities such as hemicellulose and lignin in addition to the above-mentioned amorphous cellulose, so that the interior of the fiber becomes porous. Thereby, in the step of applying a mechanical shearing force to the cellulose fiber and the dispersant (for example, a surfactant) during the kneading step described later, the cellulose fiber is easily subjected to a mechanical treatment, and the cellulose fiber is easily made fine. As a result, the surface area of the cellulose fiber is increased, and the control of the composite with a dispersant (for example, a surfactant) is facilitated.

  The hydrolysis method is not particularly limited, and examples thereof include acid hydrolysis, alkali hydrolysis, hydrothermal decomposition, steam explosion, and microwave decomposition. These methods may be used alone or in combination of two or more. In the method of acid hydrolysis, for example, α-cellulose obtained as a pulp from a fibrous plant is used as a cellulose raw material, and in a state where this is dispersed in an aqueous medium, an appropriate amount of protonic acid, carboxylic acid, Lewis acid, heteropoly acid, etc. In addition, by heating while stirring, the average degree of polymerization can be easily controlled. The reaction conditions such as temperature, pressure, time and the like at this time vary depending on the type of cellulose, the concentration of cellulose, the type of acid, the concentration of acid, and the like, but are appropriately adjusted so as to achieve a desired average degree of polymerization. For example, there is a condition that the cellulose is treated at 100 ° C. or more and under pressure for 10 minutes or more using a 2% by mass or less aqueous mineral acid solution. Under these conditions, a catalyst component such as an acid penetrates into the cellulose fiber, promotes hydrolysis, reduces the amount of the catalyst component used, and facilitates subsequent purification. The dispersion of the cellulose raw material at the time of hydrolysis may contain a small amount of an organic solvent in addition to water, as long as the effects of the present invention are not impaired.

  Oxidized or esterified cellulose fibers may be used as long as the effects of the present invention are not impaired. As an example, after oxidizing a cellulose fiber by 2,2,6,6-tetramethylpiperidine-1-oxyl radical as shown in Cellulose (1998) 5,153-164, washing and mechanical defibration are performed. A finely divided cellulose fiber obtained by passing through may be used.

  The amount of the cellulose fiber based on 100 parts by mass of the polyamide is preferably in the range of 0.1 to 100 parts by mass. The lower limit of the amount of the cellulose fiber is more preferably 0.5 part by mass, further preferably 1 part by mass, and most preferably 2 parts by mass. The upper limit of the amount of the cellulose fiber is more preferably 80 parts by mass, further preferably 70 parts by mass, and most preferably 60 parts by mass. From the viewpoint of the balance between the processability and the mechanical properties, it is desirable that the amount of the cellulose fibers be within the above range.

≪Hemicellulose and lignin≫
In one aspect, the resin composition further comprises hemicellulose and / or lignin. In plant-derived cellulose, polysaccharides generally called hemicellulose and aromatic compounds generally called lignin exist between microfibrils and between microfibril bundles. In one embodiment, it is preferable that these components are not completely removed in the production process of the cellulose fiber but are contained in a content within a suitable range. Hemicellulose is a polysaccharide composed of sugars such as mannan and xylan, and has a role of hydrogen bonding with cellulose to link microfibrils. Further, since the solubility parameter (SP value) of hemicellulose is on the hydrophobic side of cellulose, it is considered that hemicellulose has an effect of reducing the SP value difference between the thermoplastic resin and the cellulose fiber.

  The content of hemicellulose varies depending on the plant species of the raw material and the pretreatment step when producing cellulose fibers. The amount of hemicellulose in the polyamide resin composition is preferably at least 1 part by mass, more preferably at least 2 parts by mass, still more preferably at least 3 parts by mass, and preferably at most 20 parts by mass, based on 100 parts by mass of the cellulose fibers. , 18 parts by mass or less, more preferably 15 parts by mass or less. When hemicellulose is contained in the above-described range, the affinity between the polyamide resin and the cellulose fiber is improved, and the dispersibility and strength of the resin composition are improved.

Lignin is a compound having an aromatic ring, and is known to be covalently bonded to hemicellulose in the cell wall of a plant. The amount of lignin in the resin composition of the present invention is preferably at least 0.1 part by mass, more preferably at least 0.2 part by mass, further preferably at least 0.3 part by mass, based on 100 parts by mass of the cellulose fibers. It is preferably at most 10 parts by mass, more preferably at most 5 parts by mass, even more preferably at most 3 parts by mass. Since lignin is a compound that is more hydrophobic than hemicellulose, the effect of alleviating the SP value difference between the polyamide resin and the cellulose fiber is further increased. When an appropriate amount of lignin is present, low molecular weight components generated by the peeling reaction of cellulose can be adsorbed and stabilized by chelation between the lignin's three-dimensional network structure and the phenolic hydroxy group of cellulose, resulting in coloration and odor. It is presumed that the effect of suppressing is larger. It is preferable that the amounts of hemicellulose and lignin do not exceed the above ranges, respectively, from the viewpoint of preventing the heat resistance of the resin composite from lowering and the resulting discoloration from being induced.
The above contents of hemicellulose and lignin are values measured by the method described in [Example] of the present disclosure, respectively.

  The amount of hemicellulose can be adjusted to a desired amount by performing a purification treatment on a natural wood raw material having a high hemicellulose content, or when a raw material having a low hemicellulose content is used, A desired amount can be adjusted by adding hemicellulose obtained by extraction from another raw material. At this time, the structure such as the terminal of hemicellulose may be partially different from a natural product by purification or extraction treatment.

  In addition, the amount of lignin can be adjusted to a desired amount by subjecting a natural wood raw material having a high lignin content to a purification treatment, or a raw material having a low lignin content can be used. Can be adjusted to a desired amount by adding lignin obtained by extraction treatment from another raw material. At this time, the structure such as the terminal of lignin may be partially different from a natural product by purification or extraction treatment.

≪Dispersant≫
The resin composition of the present invention can include a dispersant as an additional component. In one aspect, the dispersant has a dynamic surface tension of 60 mN / m or less. In one aspect, the dispersant is a surfactant. The dispersant contributes to improving the dispersibility of the cellulose fibers in the polyamide. The preferred amount is within a range of 50 parts by mass or less of the dispersant based on 100 parts by mass of the cellulose fiber. A more preferred upper limit is 45 parts by mass, still more preferably 40 parts by mass, still more preferably 35 parts by mass, and particularly preferably 30 parts by mass. Since it is an additional component, the lower limit is not particularly limited. However, by adding 0.1 parts by mass or more based on 100 parts by mass of the cellulose fiber, handleability can be improved. The lower limit is more preferably 0.5 parts by mass, and most preferably 1 part by mass.

  Typical dispersants include those having a carbon atom as a basic skeleton and having a functional group composed of an element selected from carbon, hydrogen, oxygen, nitrogen, chlorine, sulfur, and phosphorus. As long as the molecule has the above-mentioned structure, a compound in which an inorganic compound and the above functional group are chemically bonded is also preferable.

  The dispersant may be used alone or as a mixture of two or more dispersants. In the case of a mixture, the characteristic value (eg, static surface tension, dynamic surface tension, SP value) of the dispersant of the present disclosure means the value of the mixture.

  In the present embodiment, the dispersant preferably has a static surface tension of 20 mN / m or more. This static surface tension refers to the surface tension measured by the Wilhelmy method. When a liquid dispersant is used at room temperature, a value measured at 25 ° C. is used. When a solid or semi-solid dispersant is used at room temperature, the dispersant is heated to a temperature equal to or higher than its melting point, is measured in a molten state, and the temperature corrected to 25 ° C is used. In the present disclosure, room temperature means 25 ° C. Further, for the purpose of facilitating the addition, the dispersant may be dissolved and diluted in an organic solvent, water, or the like. The above-mentioned static surface tension in this case means the static surface tension of the dispersant used itself.

  In addition, the method of adding the dispersant when preparing the resin composition is not particularly limited, but a method in which the polyamide, cellulose fiber and the dispersant are previously mixed and melt-kneaded, and the dispersant is added to the resin in advance, A method in which cellulose fibers are added and melt-kneaded after preliminary kneading as necessary, and a method in which cellulose fibers and a dispersant are mixed in advance and then melt-kneaded with polyamide, etc., may be used. It is also effective to add a dispersant to a dispersion liquid in which cellulose fibers are dispersed in water, dry the mixture to prepare a cellulose preparation, and then add the preparation to polyamide.

  When the static surface tension of the dispersant is within the specific range of the present disclosure, the dispersibility of the cellulose fibers in the resin is remarkably improved. Although the reason is not clear, the hydrophilic functional group in the dispersant covers the surface of the cellulose fiber by way of a hydroxyl group and a hydrogen bond on the surface of the cellulose fiber, thereby inhibiting the interface formation with the resin. It is thought that it is. It is considered that, since the hydrophilic group is disposed on the cellulose fiber side, a hydrophobic atmosphere is formed on the resin side, and the affinity with the resin side is also increased.

  The preferred lower limit of the static surface tension of the dispersant is 23 mN / m, more preferably 25 mN / m, still more preferably 30 mN / m, still more preferably 35 mN / m, and most preferably 39 mN / m. The preferred upper limit of the static surface tension of the dispersant is 72.8 mN / m, more preferably 60 mN / m, still more preferably 50 mN / m, and most preferably 45 mN / m.

  The dispersant has both the affinity for polyamide and the affinity for cellulose fiber, and exhibits properties such as fine dispersibility of cellulose fiber in resin, fluidity of resin composition, and strength and elongation of resin molded article. From the viewpoint, it is preferable to set the static surface tension of the dispersant to a specific range.

The static surface tension of the dispersant referred to in the present disclosure can be measured by using a commercially available surface tension measuring device. As a specific example, it can be measured by the Wilhelmy method using an automatic surface tension measuring device (for example, a product name “CBVP-Z” manufactured by Kyowa Interface Science Co., Ltd., using an attached glass cell). At this time, if the dispersant is liquid at room temperature, the height from the bottom to the liquid surface is set to 7 mm to 9 mm in the attached stainless steel dish, and the temperature is adjusted to 25 ° C. ± 1 ° C., and the measurement is performed. It is obtained by the following equation.
γ = (P-mg + shρg) / Lcos θ
Here, γ: static surface tension, P: balancing force, m: plate mass, g: gravitational constant, L: plate peripheral length, θ: contact angle between plate and liquid, s: plate cross-sectional area, h: ( The depth submerged from the liquid surface (until the force balances), ρ: the density of the liquid.

  Since the surface tension of a solid at room temperature cannot be measured by the above-described method, the surface tension measured at a temperature of melting point + 5 ° C. is used for convenience. When the melting point is an unknown substance, first, the melting point is measured by a visual melting point measuring method (JIS K6220), heated to a temperature equal to or higher than the melting point, and then adjusted to a temperature of the melting point + 5 ° C., and the above-mentioned Wilhelmy method is used. It is possible by measuring the surface tension.

  The dynamic surface tension of the dispersant is preferably 60 mN / m or less. The more preferable upper limit of the dynamic surface tension is 55 mN / m, more preferably 50 mN / m, still more preferably 45 mN / m, and particularly preferably 40 mN / m. A preferred lower limit of the dynamic surface tension of the dispersant is 10 mN / m. A more preferred lower limit is 15 mN / m, most preferably 20 mN / m.

The dynamic surface tension referred to here is the maximum bubble pressure method (measured the maximum pressure (maximum bubble pressure) when bubbles are generated by flowing air through a thin tube (hereinafter referred to as a probe) inserted into a liquid, Is a method of calculating the surface tension. Specifically, a measurement liquid is prepared by dissolving or dispersing the dispersant in 5% by mass in ion-exchanged water, adjusting the temperature to 25 ° C., and then using a dynamic surface tensiometer (eg, Theta Science manufactured by Eiko Seiki Co., Ltd.) Using a t-60 type probe (capillary TYPE I (manufactured by Peak Resin), single mode), refers to the value of surface tension measured at a bubble generation cycle of 10 Hz. It is obtained by the formula.
σ = ΔP · r / 2
Here, σ: dynamic surface tension, ΔP: pressure difference (maximum pressure−minimum pressure), r: capillary radius.

  Dynamic surface tension as measured by the maximum bubble pressure method refers to the dynamic surface tension of the dispersant in a fast moving field. Dispersants usually form micelles in water. A low dynamic surface tension indicates that the diffusion speed of the molecules of the dispersant from the micelle state is high, and a high dynamic surface tension means that the diffusion speed of the molecules is low.

  The fact that the dynamic surface tension of the dispersant is equal to or less than the specific value is advantageous in that the effect of significantly improving the dispersion of the cellulose fibers in the resin composition is exhibited. Although the details of the reason for the improvement of the dispersibility are unknown, the dispersant having a low dynamic surface tension has excellent diffusibility in the extruder, and can be localized at the interface between the cellulose fiber and the resin. It is considered that the ability to coat the fiber surface well contributes to the effect of improving the dispersibility. The effect of improving the dispersibility of the cellulose fiber obtained by setting the dynamic surface tension of the dispersant to a specific value or less has a remarkable effect of eliminating the strength defect of the molded article.

  As the dispersant, those having a higher boiling point than water are preferable. Note that the boiling point higher than that of water refers to a boiling point higher than the boiling point at each pressure in the water vapor pressure curve (for example, 100 ° C. under one atmosphere).

  By selecting a dispersant having a higher boiling point than water, for example, in the step of drying the cellulose fibers dispersed in water in the presence of the dispersant to obtain a cellulose formulation, water in the process of evaporation of water And the dispersing agent are substituted, and the dispersing agent is present on the surface of the cellulose fiber, so that an effect of greatly suppressing aggregation between celluloses can be obtained.

  As the dispersant, a liquid dispersant at room temperature (that is, 25 ° C.) can be preferably used from the viewpoint of handleability. A dispersant that is liquid at normal temperature has the advantage that it is easily compatible with cellulose fibers and easily penetrates into resins.

  As the dispersant, those having a solubility parameter (SP value) of 7.25 or more can be more preferably used. When the dispersant has the SP value in this range, the dispersibility of the cellulose fiber in the resin is improved.

The SP value depends on both the cohesive energy density and the molar molecular weight of a substance according to the Fosters literature (RF Fenders: Polymer Engineering & Science, vol. 12 (10), p. 2359-2370 (1974)). However, these are considered to depend on the type and number of substituents of the substance, and according to Ueda et al.'S literature (Paint Research, No. 152, Oct. 2010), the existing ones described in Examples described later are used. SP values (cal / cm ³ ) ^1/2 for major solvents have been published.

  The SP value of the dispersant can be experimentally determined from the boundary between soluble and insoluble when the dispersant is dissolved in various solvents having known SP values. For example, when 1 mL of a dispersant is dissolved in various solvents (10 mL) having different SP values in the table shown in the examples at room temperature under stirring with a stirrer for 1 hour, it can be determined whether or not the entire amount is dissolved. For example, when the dispersant is soluble in diethyl ether, the dispersant has an SP value of 7.25 or more.

  In one aspect, the dispersant is a surfactant. Examples of the surfactant include a compound having a chemical structure in which a hydrophilic substituent and a hydrophobic substituent are covalently bonded, and those used in various uses such as food and industrial use can be used. For example, the following may be used alone or in combination of two or more. In a particularly preferred embodiment, the dispersant is a surfactant having a specific dynamic surface tension as described above.

  As the surfactant, any of an anionic surfactant, a nonionic surfactant, an amphoteric surfactant, and a cationic surfactant can be used. In the above, an anionic surfactant and a nonionic surfactant are preferable, and a nonionic surfactant is more preferable.

  Examples of the anionic surfactant include fatty acid sodium (fatty acid), sodium fatty acid potassium, and sodium alpha sulfo fatty acid ester as fatty acid (anion), and linear sodium alkylbenzene sulfonate as linear alkylbenzene based. Alcohols (anions) include sodium alkyl sulfates, sodium alkyl ether sulfates, and the like. Alpha-olefins include sodium alpha-olefin sulfonates, and normal paraffins include sodium alkyl sulfonates. It is also possible to use one kind or a mixture of two or more kinds.

  Examples of the nonionic surfactant include fatty acid-based (nonionic) glycolipids such as sucrose fatty acid esters, sorbitan fatty acid esters, and polyoxyethylene sorbitan fatty acid esters, and fatty acid alkanolamides. Examples of the (ion) include polyoxyethylene alkyl ethers, and examples of the alkylphenol-based compound include polyoxyethylene alkyl phenyl ether. These may be used alone or in combination of two or more.

  Examples of the amphoteric surfactant include an amino acid surfactant such as sodium alkylamino fatty acid, a betaine surfactant such as alkyl betaine, and an amine oxide surfactant such as alkylamine oxide. It is also possible to use a mixture of more than one species.

  Examples of the cationic surfactant include quaternary ammonium salts, such as alkyltrimethylammonium salts and dialkyldimethylammonium salts. These can be used alone or in combination of two or more. .

  The surfactant may be a derivative of a fat. Examples of fats and oils include esters of fatty acids and glycerin, which usually take the form of triglyceride (tri-O-acylglycerin). Dry oils, semi-dry oils, classified as non-drying oils in order of being easily solidified by oxidation with fatty oils, edible, those used for various purposes such as industrial use, for example, the following, One or two or more of them are used in combination.

  Examples of oils and fats include animal and vegetable oils such as terpin oil, tall oil, rosin, white squeezed oil, corn oil, soybean oil, sesame oil, rapeseed oil (canola oil), rice oil, bran oil, camellia oil, safflower oil (safflower oil) , Palm oil (palm kernel oil), cottonseed oil, sunflower oil, perilla oil (EB oil), linseed oil, olive oil, peanut oil, almond oil, avocado oil, hazelnut oil, walnut oil, grape seed oil, mustard oil, Lettuce oil, fish oil, whale oil, shark oil, liver oil, cocoa butter, peanut butter, palm oil, lard (pork tallow), het (tallow fat), chicken oil, rabbit fat, sheep fat, horse fat, schmaltz, milk fat (butter, Grease, etc.), hardened oils (margarine, shortening, etc.), castor oil (vegetable oil) and the like.

  In particular, among the above-mentioned animal and vegetable oils, terpin oil, tall oil, and rosin are preferable from the viewpoint of affinity for the cellulose fiber surface and uniform coating properties.

  Terpine oil (also referred to as terbin oil) is an essential oil obtained by steam distillation of pine tree chips or pine resin (matsuya) obtained from those trees. Both pine essential oil and turpentine are Say. Examples of the terpin oil include gum turpentine oil (obtained by steam distillation of pine resin), wood turpentine oil (obtained by steam distillation or carbonization of pine tree chips), turpentine sulfate Oil (obtained by distilling chips when heat-treated during sulphate pulp production) and turpentine sulphite oil (obtained by distillation when heat-treated chips during sulphite pulp production), almost colorless To a pale yellow liquid, mainly composed of α-pinene and β-pinene except for turpentine sulfite oil. Turpentine sulfite oil contains p-cymene as a main component unlike other turpentine oils. If the above-mentioned components are contained, derivatives of the above-mentioned terpin oil, each of which may be used alone or as a mixture of a plurality of them, can be used as the surfactant of the present invention.

  Tall oil is an oil composed mainly of resins and fatty acids, which is a by-product of making kraft pulp using pine wood as a raw material. As the tall oil, a tall fat containing oleic acid and linoleic acid as main components, or a tall rosin containing a diterpenoid compound having 20 carbon atoms such as abietic acid as a main component may be used.

  Rosin is a residue remaining after collecting balsams such as rosin, which is the sap of pinaceous plants, and distilling turpentine essential oil, and is a natural resin mainly composed of rosin acid (abietic acid, parastolic acid, isopimaric acid, etc.). It is. Also called colophony or colophonium. Among them, tall rosin, wood rosin, and gum rosin can be suitably used. Rosin derivatives obtained by subjecting these rosins to various stabilization treatments, esterification treatments, purification treatments and the like can be used as surfactants. The stabilization treatment means that the rosin is subjected to hydrogenation, disproportionation, dehydrogenation, polymerization treatment and the like. Further, the esterification treatment refers to a treatment in which the rosin or the rosin subjected to the stabilization treatment is reacted with various alcohols to form a rosin ester. Various known alcohols or epoxy compounds can be used for the production of the rosin ester. Examples of the alcohol include monohydric alcohols such as n-octyl alcohol, 2-ethylhexyl alcohol, decyl alcohol, and lauryl alcohol; dihydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, and neopentyl glycol; Trihydric alcohols such as glycerin, trimethylolethane, trimethylolpropane, and cyclohexanedimethanol; and tetrahydric alcohols such as pentaerythritol and diglycerin. Also, isopentyldiol, ethylhexanediol, erythrulose, ozonized glycerin, caprylyl glycol, glycol, (C15-18) glycol, (C20-30) glycol, glycerin, diethylene glycol, diglycerin, dithiaoctanediol, DPG, Thioglycerin, 1,10-decanediol, decylene glycol, triethylene glycol, trimethylhydroxymethylcyclohexanol, phytantriol, phenoxypropanediol, 1,2-butanediol, 2,3-butanediol, butylethylpropanediol , BG, PG, 1,2-hexanediol, hexylene glycol, pentylene glycol, methylpropanediol, menthandiol, lauryl glycol, etc. Alcohol may be used. In addition, those classified as sugar alcohols such as inositol, erythritol, xylitol, sorbitol, maltitol, mannitol, and lactitol are also included in the polyhydric alcohol.

  Further, as the alcohol, an alcoholic water-soluble polymer can also be used. Alcoholic water-soluble polymers include polysaccharides / mucopolysaccharides, those classified as starch, those classified as polysaccharide derivatives, those classified as natural resins, those classified as cellulose and derivatives, proteins -Those classified as peptides, those classified as peptide derivatives, those classified as synthetic homopolymers, those classified as acrylic (methacrylic acid) acid copolymers, those classified as urethane polymers, Examples include those classified as laminates, those classified as cationized polymers, and those classified as other synthetic polymers, and those which are water-soluble at room temperature can be used. More specifically, sodium polyacrylate, cellulose ether, calcium alginate, carboxyvinyl polymer, ethylene / acrylic acid copolymer, vinyl pyrrolidone polymer, vinyl alcohol / vinyl pyrrolidone copolymer, nitrogen-substituted acrylamide polymer, poly Cationic polymers such as acrylamide and cationized guar gum, dimethylacrylammonium polymer, acrylic acid methacrylate acrylic copolymer, POE / POP copolymer, polyvinyl alcohol, pullulan, agar, gelatin, tamarind seed polysaccharide, xanthan gum, carrageenan , High methoxyl pectin, low methoxyl pectin, guar gum, gum arabic, arabinogalactan, karaya gum, tragacanth gum, alginic acid, albumin, casei , Curdlan, gellan gum, dextran, cellulose (which is not a cellulose fiber of the present disclosure), polyethylene imine, polyethylene glycol, cationized silicone polymer and the like.

  Among the various rosin esters described above, since the coating properties of the cellulose fiber surface and the dispersibility of the cellulose preparation in the resin tend to be further promoted, those in which rosin and a water-soluble polymer are esterified are preferable. Esterified products with polyethylene glycol (also referred to as rosin ethylene oxide adduct, polyoxyethylene glycol resin acid ester, and polyoxyethylene rosin acid ester) are particularly preferable.

  As the hardened castor oil type surfactant, for example, hydrogenated hydrogenated castor oil (castor oil, castor oil, castor oil), which is a kind of vegetable oil collected from castor seeds of Euphorbiaceae, etc. Is a hydrophobic group, and a hydroxyl group in the structure thereof and a hydrophilic group such as a PEO chain are covalently bonded. The components of castor oil are glycerides of unsaturated fatty acids (87% ricinoleic acid, 7% oleic acid, 3% linoleic acid) and small amounts of saturated fatty acids (3% palmitic acid, stearic acid, etc.). In addition, typical POE group structures include those having 4 to 40 ethylene oxide (EO) residues, and typical examples include those having 15 to 30 ethylene oxide (EO) residues. The EO residue of nonylphenol ethoxylate is preferably 15 to 30, more preferably 15 to 25, and particularly preferably 15 to 20.

  Examples of the mineral oil derivatives include greases such as calcium soap-based grease, calcium composite soap-based grease, sodium soap-based grease, aluminum soap-based grease, and lithium soap-based grease.

  The surfactant may be an alkylphenyl type compound, for example, an alkylphenol ethoxylate, that is, a compound obtained by ethoxylating an alkylphenol with ethylene oxide. Alkylphenol ethoxylates are nonionic surfactants. Since a hydrophilic polyoxyethylene (POE) chain and a hydrophobic alkylphenol group are linked by an ether bond, it is also called a poly (oxyethylene) alkylphenyl ether. Generally, a series of products having different average chain lengths are commercially available as a mixture of a large number of compounds having different alkyl chain lengths and POE chain lengths. Although the alkyl chain length is commercially available having 6 to 12 carbon atoms (excluding the phenyl group), typical alkyl group structures include nonylphenol ethoxylate and octylphenol ethoxylate. In addition, typical POE group structures include those having 5 to 40 ethylene oxide (EO) residues, and typical examples include those having 15 to 30 ethylene oxide (EO) residues. The EO residue of nonylphenol ethoxylate is preferably 15 to 30, more preferably 15 to 25, and particularly preferably 15 to 20.

  The surfactant may be a β-naphthyl-type compound. For example, a β-monosubstituted compound containing naphthalene in a part of its chemical structure and having a carbon at the 2 or 3 or 6 or 7 position of the aromatic ring bonded to a hydroxyl group. Compounds in which a body and a hydrophilic group such as a PEO chain are covalently bonded. In addition, typical POE group structures include those having 4 to 40 ethylene oxide (EO) residues, and typical examples include those having 15 to 30 ethylene oxide (EO) residues. The EO residue is preferably 15 to 30, more preferably 15 to 25, and particularly preferably 15 to 20.

The surfactant may be a bisphenol A-type compound. For example, the surfactant may include bisphenol A (chemical formula: (CH ₃ ) ₂ C (C ₆ H ₄ OH) ₂ ) in a part of its chemical structure. A compound in which two phenol groups in the inside and a hydrophilic group such as a PEO chain are covalently bonded. In addition, typical POE group structures include those having 4 to 40 ethylene oxide (EO) residues, and typical examples include those having 15 to 30 ethylene oxide (EO) residues. The EO residue of nonylphenol ethoxylate is preferably 15 to 30, more preferably 15 to 25, and particularly preferably 15 to 20. This EO residue indicates an average value obtained by adding two ether bonds when one molecule has two ether bonds.

  The surfactant may be a styrenated phenyl type compound. For example, a styrenated phenyl group is included in a part of its chemical structure, and a phenol group in the structure and a hydrophilic group such as a PEO chain are covalently bonded. Compounds which have been mentioned. The styrenated phenyl group has a structure in which one to three molecules of styrene are added to the benzene ring of a phenol residue. In addition, typical POE group structures include those having 4 to 40 ethylene oxide (EO) residues, and typical examples include those having 15 to 30 ethylene oxide (EO) residues. The EO residue of nonylphenol ethoxylate is preferably 15 to 30, more preferably 15 to 25, and particularly preferably 15 to 20. This EO residue indicates an average value obtained by adding two ether bonds when one molecule has two ether bonds.

  Specific preferred examples of the surfactant include, for example, acyl amino acid salts such as acyl gutamate, higher alkyl sulfates such as sodium laurate, sodium palmitate, sodium lauryl sulfate, potassium lauryl sulfate, and polyoxyethylene lauryl. Anionic surfactants such as alkyl ether sulfates such as triethanolamine sulfate and sodium polyoxyethylene lauryl sulfate; N-acyl sarcosinates such as sodium lauroyl sarcosine; alkyls such as stearyltrimethylammonium chloride and lauryltrimethylammonium chloride Trimethylammonium salt, distearyldimethylammonium dialkyldimethylammonium chloride, (N, N'-dimethyl-3,5-methylenepiperidinium) chloride, cetylene chloride Cationic surfactants such as alkylpyridinium salts such as pitidinium, alkyl quaternary ammonium salts, alkylamine salts such as polyoxyethylene alkylamine, polyamine fatty acid derivatives, and amyl alcohol fatty acid derivatives; 2-undecyl-N, N, N- (Hydroxyethyl carboxymethyl) 2-imidazoline sodium, 2-cocoyl-2-imitazolinium hydroxide-1-carboxyethyloxy disodium salt and other imidazoline amphoteric surfactants, 2-heptadecyl-N-carboxymethyl- Amphoteric surfactants such as betaine-based amphoteric surfactants such as N-hydroxyethylimidazolinium betaine, betaine lauryldimethylaminoacetate, betaine, alkylbetaine, amidobetaine and sulfobetaine, sorbitan nomooleate, and sorbie Monomoisostearate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan sesquioleate, sorbitan trioleate, diglycerol penta-2-ethylhexylate sorbitan, diglycerol tetra-2-ethylhexylate sorbitan, etc. Sorbitan fatty acid esters, glycerin monostearate, glycerin polyglycerin fatty acids such as α, α'-oleic acid pyroglutamate, glyceryl monostearate malic acid, propylene glycol fatty acid esters such as propylene glycol monostearate, curing Castor oil derivative, glycerin alkyl ether, polyoxyethylene-sorbitan monostearate, polyoxyethylene-sorbitan monooleate Polyoxyethylene-sorbitan fatty acid esters such as polyoxyethylene-sorbitan tetraoleate, polyoxyethylene-sorbit monolaurate, polyoxyethylene-sorbit monooleate, polyoxyethylene-sorbit pentaoleate, polyoxyethylene- Polyoxyethylene-glycerin fatty acid esters such as sorbit monostearate, polyoxyethylene-glycerin monoisostearate, polyoxyethylene-glycerin triisostearate, polyoxyethylene monooleate, polyoxyethylene distearate, poly Polyoxyethylene fatty acid esters such as oxyethylene monodioleate and ethylene glycol cysteate, polyoxyethylene hydrogenated castor oil, polyoxyethylene Castor oil, polyoxyethylene hydrogenated castor oil monoisostearate, polyoxyethylene hydrogenated castor oil triisostearate, polyoxyethylene hydrogenated castor oil monopyroglutamic acid monoisostearate diester, polyoxyethylene hydrogenated castor oil maleic acid, etc. Nonionic surfactants such as oxyethylene castor oil-hardened castor oil derivatives and the like can be mentioned.

  Among the above, a surfactant having a polyoxyethylene chain as a hydrophilic group, a carboxylic acid, or a hydroxyl group is preferable in terms of affinity with cellulose fibers, and a polyoxyethylene-based surfactant having a polyoxyethylene chain as a hydrophilic group. Agents (polyoxyethylene derivatives) are more preferred, and nonionic polyoxyethylene derivatives are even more preferred. The polyoxyethylene chain length of the polyoxyethylene derivative is preferably 3 or more, more preferably 5 or more, still more preferably 10 or more, and particularly preferably 15 or more. The longer the chain length, the higher the affinity with the cellulose fiber. However, in terms of balance with coating properties (localization at the interface between the resin and the cellulose fiber), the upper limit is preferably 60 or less, and 50 or less. More preferably, it is more preferably 40 or less, particularly preferably 30 or less, and most preferably 20 or less.

  In order to mix cellulose fibers with polyamide satisfactorily, it is preferable to use those having a polyoxypropylene chain instead of a polyoxyethylene chain as a hydrophilic group. The polyoxypropylene chain length is preferably 3 or more, more preferably 5 or more, still more preferably 10 or more, and particularly preferably 15 or more. The longer the chain length is, the higher the affinity with the cellulose fiber is. However, in the balance with the coating property, the upper limit is preferably 60 or less, more preferably 50 or less, still more preferably 40 or less, and particularly preferably 30 or less. , 20 or less is most preferred.

  Among the above-mentioned surfactants, particularly, as the hydrophobic group, alkyl ether type, alkyl phenyl ether type, rosin ester type, bisphenol A type, β-naphthyl type, styrenated phenyl type, and hydrogenated castor oil type have affinity for resin. , So that it can be suitably used. The preferred alkyl chain length (in the case of alkylphenyl, the number of carbon atoms excluding the phenyl group) is preferably 5 or more, more preferably 10 or more, still more preferably 12 or more, and particularly preferably 16 or more. When the resin is a polyolefin, the upper limit is not set because the affinity with the resin increases as the number of carbon atoms increases, but the upper limit is preferably 30, and more preferably 25.

  Among these hydrophobic groups, those having a cyclic structure or those having a bulky multifunctional structure are preferable, and those having a cyclic structure include alkylphenyl ether type, rosin ester type, bisphenol A type, β naphthyl type, The styrenated phenyl type is preferred, and the cured castor oil type is particularly preferred as having a polyfunctional structure. Among these, rosin ester type and hardened castor oil type are most preferable.

  Therefore, in a particularly preferred embodiment, the surfactant is one or more selected from the group consisting of rosin derivatives, alkylphenyl derivatives, bisphenol A derivatives, β-naphthyl derivatives, styrenated phenyl derivatives, and hydrogenated castor oil derivatives.

  Examples of the dispersant other than the surfactant include at least one compound selected from the group consisting of fats and oils, fatty acids, and mineral oils, and compounds not included in the surfactant. Examples of the fats and oils include those exemplified as fats and oils in the section of the surfactant.

  Fatty acids refer to compounds represented by the general formula CnHmCOOH (n and m are integers), and those used for various purposes such as food and industrial use can be used. For example, the following may be used alone or in combination of two or more.

  For example, as saturated fatty acids, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid Acids, margaric acid, stearic acid, nonadecylic acid, arachidic acid, henicosylic acid, behenic acid, tricosylic acid, lignoceric acid and the like.Examples of unsaturated fatty acids include, for example, α-linolenic acid, stearidonic acid, eicosapentaenoic acid, Ω-3 fatty acids such as docosapentaenoic acid and docosahexaenoic acid; ω-6 fatty acids such as linoleic acid, γ-linolenic acid, dihomo-γ-linolenic acid, arachidonic acid and docosapentaenoic acid; palmitoleic acid, vaccenic acid, paulin Ω-7 fatty acids such as acids; oleic acid, elaidic acid, L Acid, omega-9 fatty acids such as nervonic acid.

  Mineral oils include greases such as liquid paraffin, silicon oil, and silicon grease; naphthenic and paraffinic mineral oils; parts obtained by mixing PAO and esters (or hydrocracked oils) with mineral oils and highly hydrocracked oils Synthetic oil; chemical synthetic oil such as PAO (polyalphaolefin), total synthetic oil, synthetic oil, and the like.

  The amount of the dispersant is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, still more preferably 40 parts by mass or less, still more preferably 35 parts by mass or less, particularly preferably 30 parts by mass or less with respect to 100 parts by mass of the cellulose fibers. It is. Since it is an additional component, the lower limit is not particularly limited. However, when the total amount is 0.1 parts by mass or more with respect to 100 parts by mass of the cellulose fiber, handleability can be enhanced. The total amount is more preferably at least 0.5 part by mass, particularly preferably at least 1 part by mass.

製造 Method for producing resin composition≫
The method for producing the resin composition of the present invention is not particularly limited, but specific examples include the following methods.
A method of mixing a polyamide resin monomer and an aqueous dispersion of cellulose fibers, performing a polymerization reaction, extruding the obtained resin composition into strands, solidifying by cooling in a water bath, and obtaining a pellet-shaped molded article, a uniaxial or Using a twin-screw extruder, melt-kneading a mixture of resin and cellulose fiber, extruding into a strand, cooling and solidifying in a water bath to obtain a pellet-shaped molded article, a single-screw or twin-screw extruder. A method of melt-kneading a mixture of a resin and a cellulose fiber, extruding into a rod or a cylinder and cooling to obtain an extruded product, a single-screw or a twin-screw extruder, a mixture of the resin and a cellulose fiber , Melt-kneading a mixture of resin and cellulose fiber using a single-screw or twin-screw extruder. The extruded, cooled and solidified in a water bath, methods and the like to obtain a pellet-shaped molded. In a preferred embodiment, the polymerization reaction of the raw material monomer of the polyamide is carried out in the presence of cellulose fibers containing water.

  The moisture content of the resin composition of the present invention is not particularly limited, but is preferably 10 ppm or more to suppress the increase in the molecular weight of the polyamide at the time of melting, and is 1200 ppm or less to suppress the hydrolysis of the polyamide at the time of melting. It is preferably at most 900 ppm, more preferably at most 900 ppm, most preferably at most 700 ppm. The moisture content is a value measured using a Karl Fischer moisture meter by a method based on ISO 15512.

  As a specific example of a method of melt-kneading a mixture of a resin and a cellulose fiber, a resin and a cellulose mixed powder mixed in a desired ratio are mixed in the presence / absence of a dispersant (for example, a surfactant). After mixing at a time, a method of melt-kneading all at once, a method of melt-kneading a resin and a dispersant if necessary, a method of adding a cellulose mixed powder mixed at a desired ratio and a dispersant as needed, and a method of further melt-kneading, After mixing the cellulose mixed powder and water mixed in a desired ratio, and the dispersant as necessary, a method of melt-kneading all at once, the resin and the dispersant were melt-kneaded as needed, and then mixed in a desired ratio A method in which a cellulose mixed powder, water and, if necessary, a dispersing agent are added, and further melt-kneaded, may be mentioned.

  The resin composition of the present invention can be provided in various shapes. Specific examples include resin pellets, sheets, fibers, plates, rods, and the like, and the resin pellets are more preferable in terms of ease of post-processing and transportation. Preferable pellet shapes at this time include a round shape, an elliptical shape, a cylindrical shape, and the like, which differ depending on a cutting method at the time of extrusion. Pellets cut by a cutting method called underwater cut are often round, and pellets cut by a cutting method called hot cut are often round or oval, and cuts called strand cuts The pellets cut by the method often have a columnar shape. In the case of a round pellet, the preferred size is 1 mm or more and 3 mm or less as a pellet diameter. Further, in the case of a cylindrical pellet, a preferred diameter is 1 mm or more and 3 mm or less, and a preferred length is 2 mm or more and 10 mm or less. The above-mentioned diameter and length are desirably not less than the lower limit from the viewpoint of operation stability during extrusion, and desirably not more than the upper limit from the viewpoint of biting into a molding machine in post-processing.

  The resin composition of the present invention can be used as various resin molded articles. There is no particular limitation on the method for producing the resin molded article, and any production method may be used, but an injection molding method, an extrusion molding method, a blow molding method, an inflation molding method, a foam molding method, or the like can be used. Of these, the injection molding method is most preferable from the viewpoint of design and cost.

  INDUSTRIAL APPLICABILITY The resin composition of the present invention has high mechanical properties and low linear expansion properties, and has stagnation stability that can be used for large parts, and thus can be suitably used for various large parts applications.

  The present invention will be further described based on examples, but the present invention is not limited to these examples.

[Raw materials and evaluation method]
Hereinafter, the used raw materials and the evaluation method will be described.

≪Polyamide resin≫
・ "UBE Nylon 1013B" Polyamide 6 (hereinafter referred to as PA) manufactured by Ube Industries, Ltd.
The ratio of carboxyl end groups is ([COOH] / [total end groups]) = 0.58
・ “Ε-caprolactam” manufactured by Ube Industries, Ltd. ・ “Adipic acid” manufactured by Tokyo Chemical Industry Co., Ltd. (hereinafter, referred to as terminal adjuster-A)
-"Benzoic acid" manufactured by Tokyo Chemical Industry Co., Ltd. (hereinafter referred to as terminal adjuster-B)
"Hexamethylenediamine" manufactured by Tokyo Chemical Industry Co., Ltd. (hereinafter, referred to as terminal adjuster-C)

≪Cellulose fiber≫
・ Cellulose fiber A (hereinafter sometimes abbreviated as CF-A)
After cutting the linter pulp, it was heated in hot water of 120 ° C. or more for 3 hours using an autoclave, and the purified pulp from which the hemicellulose portion had been removed was squeezed to a solid content of 1.5% by mass in pure water. After the fibers were highly shortened and fibrillated by beating treatment, the fibers were fibrillated at the same concentration with a high-pressure homogenizer (operating pressure: 85 MPa for 10 times) to obtain fibrillated cellulose. Here, in the beating treatment, a disc refiner is used, and after processing for 4 hours with a beating blade having a high cutting function (hereinafter, referred to as a cutting blade), a beating blade having a high defibrating function (hereinafter, referred to as a defibrating blade) is used. Beating was further performed for 1.5 hours to obtain cellulose fiber A. The properties of the obtained cellulose fibers were evaluated by the methods described below. The results are shown below.
Average L / D = 300
Average fiber diameter = 90 nm
Crystallinity = 80%
Degree of polymerization = 600

・ Cellulose fiber B (hereinafter sometimes abbreviated as CF-B)
The following cellulose fiber B was obtained under the same conditions as in CF-A, except that the defibration treatment was performed five times at an operating pressure of 85 MPa.
Average L / D = 450
Average fiber diameter = 400 nm
Crystallinity = 82%
Degree of polymerization = 700

・ Cellulose fiber C (hereinafter sometimes abbreviated as CF-C)
Bacterial cellulose was produced according to the method described in Production Example 1 and Example 8 of Japanese Patent No. 58885658, and the following dispersion of cellulose fiber C was obtained.
Average L / D = 1000
Average fiber diameter = 40 nm
Crystallinity = 95%
Degree of polymerization = 650

・ Cellulose fiber D (hereinafter sometimes abbreviated as CF-D)
Commercially available lignin (manufactured by Nacalai Tesque, Inc.) was added to CF-C to obtain a dispersion of cellulose fiber D.

・ Cellulose fiber E (hereinafter sometimes abbreviated as CF-E)
Hemicellulose produced by the bamboo hemicellulose production method described in Wood Research, No. 34 (1965), p. 100 was added to CF-C to obtain a dispersion of cellulose fibers E.

・ Cellulose fiber F (hereinafter sometimes abbreviated as CF-F)
The following cellulose fibers D were obtained under the same conditions as in CF-A except that the raw material was abaca pulp.
Average L / D = 500
Average fiber diameter = 30 nm
Crystallinity = 80%
Degree of polymerization = 600

<Degree of polymerization of cellulose fiber>
It was measured by the reduced specific viscosity method using a copper ethylenediamine solution specified in the crystalline cellulose confirmation test (3) of “14th Revised Japanese Pharmacopoeia” (published by Hirokawa Shoten).
<Crystal form and crystallinity of cellulose fiber>
Using an X-ray diffractometer (manufactured by Rigaku Corporation, a multipurpose X-ray diffractometer), a diffraction image was measured by a powder method (normal temperature), and the crystallinity was calculated by a Segal method. The crystal form was also measured from the obtained X-ray diffraction image.

<Average fiber diameter and average L / D of cellulose fiber>
Cellulose fibers are made into a pure water suspension at a concentration of 1% by mass, and a high shear homogenizer (manufactured by Nippon Seiki Co., Ltd., trade name "Excel Auto Homogenizer ED-7", processing condition: rotation speed 15,000 rpm x 5 minutes) Was diluted with pure water to 0.1 to 0.5% by mass, cast on mica, and air-dried, and measured with an atomic force microscope (AFM). The measurement was performed by adjusting the magnification so that at least 100 cellulose fibers were observed, and the major axis (L), minor axis (D), and their ratio (L / L) of 100 randomly selected cellulose fibers were measured. D) was calculated, and the average of 100 cellulose fibers was calculated.

  The quantitative analysis of hemicellulose was performed by the following method. The dispersion medium is removed from the dispersion liquid of fine cellulose or the redispersion liquid of fine cellulose obtained by dissolving and removing the resin from the resin composition, the cellulose residue is recovered, and the mass of the dried sample dried at 105 ° C. is measured. did.

  The dried cellulose residue was pulverized, and the pulverized sample was extracted with a mixed solvent of alcohol (ethanol) / benzene for 6 hours using a Soxhlet extractor, and further extracted with alcohol for 4 hours to obtain a defatted sample. To 2.5 g of the defatted sample, 150 mL of distilled water, 1.0 g of sodium chlorite, and 0.2 mL of acetic acid were added, and a heat treatment was performed at 70 to 80 ° C. for 1 hour, and again 1.0 g of sodium chlorite and 0.1 g of acetic acid. The operation of adding 2 mL and heating at 70 to 80 ° C. for 1 hour was repeated 3 to 4 times until the sample became white and decolorized. The obtained sample was filtered, washed with water and acetone, dried at 105 ° C., and the mass of the holocellulose fraction was measured.

  Subsequently, 25 mL of a 17.5% by mass aqueous sodium hydroxide solution was added to 1.0 g of the holocellulose fraction, and after 3 minutes, the mixture was lightly crushed with a glass rod until it became swollen. 30 minutes after adding the aqueous sodium hydroxide solution at 20 ° C., add 25 mL of distilled water, stir exactly 1 minute, leave at 20 ° C. for 5 minutes, filter through a glass filter, Was washed until neutral. Further, 40 mL of 10% by mass acetic acid was suction-filtered, then 1 L of boiling water was suction-filtered, and the washed sample was dried at 105 ° C. until the weight became constant, and the weight of the α-cellulose fraction was measured.

From the masses of the holocellulose fraction and the α-cellulose fraction determined as described above, the content of hemicellulose was determined by the following equation.
Holocellulose (%) = holocellulose fraction (g) / sample (anhydrous base) (g) x 100
α-cellulose (%) = α-cellulose fraction (g) / sample (anhydrous base) (g) × 100
Hemicellulose (%) = holocellulose (%)-α-cellulose (%)

  The quantitative analysis of lignin was performed by the following method. To 300 mg of the defatted sample obtained during the above-described quantitative analysis of hemicellulose, 3 mL of 72% by mass sulfuric acid was added, and the mixture was allowed to stand at 30 ° C. for 1 hour. After autoclaving at 120 ° C. for 1 hour, the mixture was filtered through a glass filter before cooling to remove acid-insoluble lignin, and the filtrate was recovered. The acid-insoluble lignin was washed with distilled water and dried at 105 ° C., then the mass of the acid-insoluble lignin fraction was measured, and the filtrate was measured for absorbance with an ultraviolet-visible spectrophotometer.

The content of acid-insoluble lignin and acid-soluble lignin was calculated from the following formula. These are summed to determine the total lignin content.
Acid-insoluble lignin (%) = acid-insoluble lignin fraction (g) / sample amount (anhydrous base) (g) × 100
Acid-soluble lignin (%) = ((d × v × (As-Ab)) / (a × w)) × 100
Lignin (%) = acid-insoluble lignin (%) + acid-soluble lignin (%)
d: dilution ratio v: filtrate constant volume (L)
As: Absorbance of sample solution Ab: Absorbance of blank solution a: Absorption coefficient of lignin (110 L / g · cm)
w: Sample amount (anhydrous base) (g)

≪Dispersant≫
The following were used as dispersants.
"Brownon N-515" manufactured by Aoki Yushi Kogyo Co., Ltd. Polyoxyethylene alkyl phenyl ether: Hereinafter, simply referred to as a surfactant.
Static surface tension 34.8 mN / m, dynamic surface tension 40.9 mN / m, boiling point under normal pressure> 100 ° C

<Measurement of static surface tension>
Using each dispersant, static surface tension was measured by an Wilhelmy method using an automatic surface tension measuring device (trade name “CBVP-Z”, manufactured by Kyowa Interface Science Co., Ltd., attached glass cell). Since each dispersant was liquid at room temperature, the height from the bottom to the liquid surface was set to 7 mm to 9 mm in a stainless steel petri dish attached to the apparatus, and the temperature was measured after adjusting to 25 ° C. ± 1 ° C. Was determined by the following equation. γ = (P-mg + shρg) / Lcos θ. Here, P: balancing force, m: plate mass, g: gravitational constant, L: plate perimeter, θ: contact angle between plate and liquid, s: plate cross-sectional area, h: liquid (to the point where force is balanced) The depth sinking from the surface, ρ: the density of the liquid (1 was used because the density of the dispersant was 1 ± 0.4 g / mL).

  A solid at room temperature was heated to a temperature equal to or higher than the melting point and melted, then adjusted to a temperature of the melting point + 5 ° C., and the surface tension was measured by the Wilhelmy method described above.

<Measurement of dynamic surface tension>
Using each dispersant, bubble generation by the maximum bubble pressure method using a dynamic surface tensiometer (product name: Theta Science t-60, manufactured by Eiko Seiki Co., Ltd., probe (capillary TYPE I (manufactured by Peak Resin), single mode)) The dynamic surface tension was measured at a frequency of 10 Hz, and each dispersant was dissolved or dispersed in ion-exchanged water at 5% by mass to prepare a measurement solution, and 100 mL of the solution or dispersion was charged into a 100 mL glass beaker. The temperature was adjusted to 25 ° C. ± 1 ° C., and the measured value was used.The dynamic surface tension was determined by the following equation: σ = ΔP · r / 2, where σ: dynamic Surface tension, ΔP: pressure difference (maximum pressure−minimum pressure), r: capillary radius.

<Measurement of SP value of dispersant>
The SP value was determined from the range of the SP value of the solvent dissolved without phase separation after dropping 1 mL of each sample into 10 mL of a solvent having a known SP value in the table below at room temperature, stirring for 1 hour with a stirrer.

≪Tensile yield strength≫
Using an injection molding machine with a maximum mold clamping pressure of 75 tons, a multipurpose test piece compliant with ISO294-3 was molded, and the test was performed under the conditions compliant with JIS K6920-2. Since the polyamide resin undergoes changes due to moisture absorption, it was stored in an aluminum moisture-proof bag immediately after molding to suppress moisture absorption.

≪Linear expansion coefficient≫
From the center of the multipurpose test piece, a cubic sample of 4 mm long, 4 mm wide, and 10 mm long is cut out with a precision cut saw, and measured in a measurement temperature range of -20 to 80 ° C in accordance with ISO11359-2, and measured at 0 ° C to The expansion coefficient between 60 ° C was calculated. At this time, prior to the measurement, annealing was performed by allowing the sample to stand at 120 ° C. for 5 hours.

≪Moisture percentage≫
Using the polyamide resin composition pellets produced in Examples and Comparative Examples described below, a Karl Fischer moisture meter (Mitsubishi Chemical Analytech Co., Ltd. Coulometric titration trace moisture measuring device CA-200 type) was used in accordance with ISO 15512. And the water content (ppm) in the pellets was measured.

<< Measurement of terminal amino group concentration [NH ₂ ] >>
The weighed sample was dissolved in a 90% by mass phenol aqueous solution, and potential titration was performed at 25 ° C. with 1 / 50N hydrochloric acid to calculate.

<< Measurement of terminal carboxyl group concentration [COOH] >>
The weighed sample was dissolved in benzyl alcohol at 160 ° C., and the potential was calculated by potential titration with 1 / 50N hydrochloric acid at 25 ° C. as an indicator.

≫Coloring evaluation≫
Using the pellets obtained in Examples and Comparative Examples, the cylinder temperature of an injection molding machine with a maximum clamping pressure of 4000 tons was set to 250 ° C., and after purging was performed 10 times using the pellets, molding was performed. The colored state of the molded piece was evaluated on the following four levels.
◎ Slight coloring (light yellow)
○ Mild coloring (yellow)
△ Medium coloring (brown)
× Intense coloring (dark brown to black)

≪Odor evaluation≫
As in the case of the coloring property, the generation of odor during molding was evaluated in the following four stages.
◎ faint odor (resin derived odor)
○ Slight odor (sugar-derived odor)
△ Odor perceived around the molding machine (sugar-derived odor)
× Odor that can be perceived throughout the room (sugar-derived odor)

{Examples 1-3, 5-8, 12-17, Comparative Examples 1-3}
An aqueous dispersion was prepared so that the content of cellulose fiber described in Table 1 was 3% by mass. 70 parts by mass of the aqueous dispersion of cellulose fibers, 100 parts by mass of ε-caprolactam, and the terminal adjuster and dispersant of parts by mass shown in Table 1 were stirred and mixed by a mixer until a uniform dispersion was obtained. . Subsequently, the dispersion was stirred, heated to 240 ° C. while gradually releasing water vapor, and a polymerization reaction was performed at 240 ° C. for 1 hour. When the polymerization was completed, the obtained resin composition was discharged and cut into pellets. The obtained pellets were treated with hot water at 95 ° C., scoured, and dried. The injection molding conditions for obtaining the multipurpose test piece were a cylinder temperature of 250 ° C. and a mold temperature of 70 ° C.

Example 4
The procedure was performed in the same manner as in Example 1 except that the amount of the terminal adjuster-A was 0.16 parts by mass and the polymerization reaction time was 5 hours.

{Examples 9 to 10}
After mixing the aqueous dispersion of cellulose fibers (3% by mass) and the dispersant in parts by mass shown in Table 1 with a mixer, the dispersion is converted to 20 parts by mass of cellulose fibers using a centrifuge. Concentrated. After the concentrated dispersion was dried, pulverization was performed to obtain a powdery cellulose fiber.
PA and the powdered cellulose fibers were mixed in the parts by mass shown in Table 1, melt-kneaded with a TEM48SS extruder manufactured by Toshiba Machine Co., Ltd. at a screw rotation speed of 350 rpm and a discharge rate of 140 kg / hr, and then vacuum devolatilized. The mixture was extruded into a strand from a die, cooled in a water bath, and pelletized.

<< Example 11 >>
Except not performing drying after refining, it carried out similarly to Example 2.

As is clear from Table 1, the polyamide resin compositions obtained in Examples 1 to 17 have a carboxyl group terminal concentration and an amino group terminal concentration satisfying the formula (1), and (B) an average fiber diameter. Since it is a polyamide resin composition containing cellulose fibers of 500 nm or less, the color tone and odor reduction properties of the resin composition have been dramatically improved in addition to excellent mechanical properties. On the other hand, in the polyamide resin compositions of Comparative Examples 1 to 3, as the carboxyl group terminal ratio became smaller, the color tone and odor of the composition at the time of residence in a large-sized injection molding machine tended to deteriorate.
The polyamide resin composition of the present invention has excellent properties particularly in molding with a long cycle time using a large injection molding machine.

  The resin composition of the present invention can impart, for example, high strength and low linear expansion to a resin molded product, and is suitable for molding large parts. And can be suitably used.

Claims (8)

(A) amine terminated Concentration [-NH _2] with the carboxyl group terminal concentration [-COOH] and the following formula (1):
[-NH ₂ ] <[-COOH] (1)
A polyamide that satisfies
(B) A polyamide resin composition containing cellulose fibers having an average fiber diameter of 500 nm or less.   The polyamide resin composition according to claim 1, further comprising 0.1 to 50 parts by mass of a dispersant based on 100 parts by mass of the cellulose fiber. 3. The polyamide resin composition according to claim 1, wherein the sum of the carboxyl group terminal concentration and the amino group terminal concentration ([−NH ₂ ] + [− COOH]) of the polyamide is 10 μmol / g or more. 4. The sum of the carboxyl group terminal concentration and an amino group end concentration of the polyamide _{([-NH 2] + [-} COOH]) is not more than 500μ mol / g, a polyamide according to any one of claims 1 to 3 Resin composition.   The polyamide resin composition according to any one of claims 1 to 4, comprising 1 to 20 parts by mass of hemicellulose and / or 0.1 to 10 parts by mass of lignin based on 100 parts by mass of the cellulose fibers.   The polyamide resin composition according to any one of claims 1 to 5, wherein the polyamide resin composition is in the form of a resin pellet and has a moisture content of 1200 ppm or less.   The polyamide resin according to any one of claims 1 to 6, obtained by polymerizing a raw material monomer of the polyamide resin in the presence of cellulose fibers having an average fiber diameter of 500 nm or less in a water-containing state. Composition.   A molded article formed from the polyamide resin composition according to claim 1.