JP2019044163A - Method of producing cellulose-containing resin composition - Google Patents

Abstract

To provide a method of producing a resin composition excellent in dispersion uniformity of cellulose in the resin composition and capable of significantly reducing position dependence of mechanical strength of a molding.SOLUTION: A method of producing a resin composition comprising thermoplastic resin and cellulose comprises, in the stated order, a first step of preparing a resin-cellulose dispersion that comprises a dispersion medium containing water as a main constituent and also comprises thermoplastic resin and cellulose that are dispersed in the dispersion medium, a second step of heating and agitating the resin-cellulose dispersion and removing the dispersion medium to obtain a resin-cellulose mixture, and a third step of melting and kneading the resin-cellulose mixture obtained in the second step to obtain the resin composition.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a resin composition containing cellulose.

  Thermoplastic resins are light and excellent in processing characteristics, and thus are widely used in various fields such as automobile parts, electrical / electronic parts, office equipment housings, precision parts and the like. However, the resin alone often has insufficient mechanical properties, dimensional stability, etc., and a composite of resin and various reinforcing materials is generally used.

In recent years, cellulose has been used as a new reinforcing material for resins.
Cellulose has a high elastic modulus comparable to that of aramid fiber, but the true density is as low as 1.56 g / cm ^3, and glass (density 2.4 to 2.6 g / cm ³ ), which is a general reinforcing material, It is a material that is overwhelmingly lighter than talc (density 2.7 g / cm ³ ), and has attracted attention as a reinforcing material for resins that replaces glass fibers.

  Therefore, as a technique for dispersing cellulose in a thermoplastic resin, for example, Patent Document 1 discloses, for example, a mixture obtained by performing lipophilic treatment on powdered cellulose and uniformly dispersing it in a plasticizer, and then melt-kneading with polyolefin. The technology to do is described. Patent Document 2 describes a technique of mixing a resin, a plant fiber swollen in a special liquid, and an organic liquid. Further, in Patent Document 3, water is separated from the mixed dispersion obtained by previously mixing the cellulose dispersion with a resin powder having a specific particle size to obtain a cellulose / resin mixture, and the mixture is melt-kneaded. The technology to do is described.

JP, 2006-104874, A International Publication No. 2013/133093 JP 2008-297364 A

  Generally, in order to mix cellulose in a resin, it is necessary to dry the cellulose in advance and pulverize it. However, cellulose becomes a strong aggregate from a finely dispersed state in the process of separating from water, and is difficult to redisperse. There is a problem. This cohesive force is expressed by hydrogen bonding due to the hydroxyl group of cellulose, and is said to be very strong.

  Therefore, in order to express sufficient performance, it is necessary to give a strong shear to the cellulose and defibrate to a fiber diameter of 1 μm or less. Even if the defibration itself can be realized sufficiently, it is difficult to maintain the defibrated state in the resin, and the uniform dispersibility of cellulose in the composition is not sufficient. is there.

  If the dispersion uniformity of cellulose in the resin composition is not sufficient, a difference in the mechanical strength of the molded body will be caused, and the resulting mechanical properties will vary greatly. In this case, the molded body partially has strength defects, and the reliability as an actual product is greatly impaired. Therefore, in fact, cellulose has not been put to practical use while having excellent characteristics.

  An object of this invention is to provide the manufacturing method of the resin composition which solves said subject and has sufficient physical property stability which can be used practically.

  In order to solve the above-mentioned problems, the present inventors have intensively studied. As a result, in producing a cellulose-containing resin composition, cellulose and a thermoplastic resin are dispersed in advance in a dispersion medium containing water as a main component. The mixture was formed and stirred while heating to remove the dispersion medium, and then the resin was melted and kneaded to find that the above problems could be solved, and the present invention was achieved.

That is, the present invention includes the following aspects.
[1] A method for producing a resin composition comprising a thermoplastic resin and cellulose,
A first step of preparing a resin cellulose dispersion containing a dispersion medium containing water as a main component, and a thermoplastic resin and cellulose dispersed in the dispersion medium;
A second step of heating the resin cellulose dispersion while stirring to remove the dispersion medium to obtain a resin cellulose mixture;
A third step of melt-kneading the resin cellulose mixture obtained in the second step to obtain a resin composition;
The manufacturing method of the resin composition which contains these in this order.
[2] The method for producing a resin composition according to aspect 1, wherein the ratio of the thermoplastic resin in the resin composition is 50 to 99% by mass with respect to 100% by mass of the resin composition.
[3] The thermoplastic resin is selected from the group consisting of polyolefin resins, polyamide resins, polyester resins, polyacetal resins, polyphenylene ether resins, polyphenylene sulfide resins, and mixtures of any two or more thereof. The manufacturing method of the resin composition of the said aspect 1 or 2.
[4] The method for producing a resin composition according to the above aspect 3, wherein the thermoplastic resin is a polyamide-based resin.
[5] The method for producing a resin composition according to aspect 4, wherein the polyamide-based resin is polyamide 6, polyamide 6,6, or a mixture thereof.
[6] The method for producing a resin composition according to any one of the above aspects 1 to 5, wherein the cellulose is cellulose fiber, cellulose whisker, or a mixture thereof.
[7] In the first step, after cellulose is dispersed in a dispersion medium to obtain a cellulose dispersion, the cellulose dispersion is added to a thermoplastic resin to obtain the resin cellulose dispersion. 7. A method for producing a resin composition according to any one of 6 above.
[8] The method for producing a resin composition according to any one of the above aspects 1 to 7, wherein more than 50% by mass of the thermoplastic resin combined with cellulose in the first step is in the form of pellets.
[9] The method for producing a resin composition according to any one of the above aspects 1 to 8, wherein the ratio of cellulose in 100% by mass of the resin cellulose dispersion obtained in the first step is 1 to 30% by mass.
[10] The method for producing a resin composition according to any one of the above aspects 1 to 9, wherein the temperature in the second step is 100 ° C. or higher and lower than 200 ° C.
[11] The method for producing a resin composition according to any one of the above aspects 1 to 10, wherein at least a part of the third step is performed in a reduced pressure state less than atmospheric pressure.
[12] The method for producing a resin composition according to any one of the above aspects 1 to 11, wherein the first to third steps are continuously carried out with an extruder.

  INDUSTRIAL APPLICABILITY The present invention can provide a method for producing a thermoplastic resin composition that gives a resin molded article sufficient mechanical properties and sufficient physical property stability to withstand practical use.

FIG. 1 is a schematic view showing the shape of a fender produced for evaluating the defect rate of the fender in Examples and Comparative Examples.

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

  The method for producing a resin composition of the present invention is a method for producing a resin composition containing a thermoplastic resin and cellulose. This manufacturing method includes a first step, a second step, and a third step. Hereinafter, it demonstrates in order.

≪First process≫
In this production method, a first step of preparing a resin cellulose dispersion in which a thermoplastic resin and cellulose are dispersed in a dispersion medium containing water as a main component is necessary.

(Thermoplastic resin)
Examples of the thermoplastic resin used in the present invention include a crystalline resin having a melting point in the range of 100 ° C. to 350 ° C., or an amorphous resin having a glass transition temperature in the range of 100 to 250 ° C. .

  The melting point of the crystalline resin here refers to the peak top temperature of the endothermic peak that appears when the temperature is increased from 23 ° C. at a rate of 10 ° C./min using a differential scanning calorimeter (DSC). When two or more endothermic peaks appear, the peak top temperature of the endothermic peak on the highest temperature side is indicated. The enthalpy of the endothermic peak at this time is desirably 10 J / g or more, and more desirably 20 J / g or more. In the measurement, it is desirable to use a sample which is once heated to a temperature condition of melting point + 20 ° C. or higher, melted the resin, and then cooled to 23 ° C. at a temperature decreasing rate of 10 ° C./min.

  The glass transition temperature of the amorphous resin as used herein means that when measured at an applied frequency of 10 Hz while increasing the temperature from 23 ° C. to 2 ° C./min using a dynamic viscoelasticity measuring device. The peak top temperature at which the storage elastic modulus is greatly reduced and the loss elastic modulus is maximized. When two or more peaks of loss elastic modulus appear, the peak top temperature of the peak on the highest temperature side is indicated. The measurement frequency at this time is desirably measured at least once every 20 seconds in order to improve measurement accuracy. The method for preparing the measurement sample is not particularly limited, but from the viewpoint of eliminating the influence of molding distortion, it is desirable to use a cut piece of a hot press-molded product, and the size (width and thickness) of the cut piece is as much as possible. A smaller value is desirable from the viewpoint of heat conduction.

  Specific examples of thermoplastic resins that can be suitably used in the present invention include polyolefin resins, polyamide resins, polyester resins, polyacetal resins, polyphenylene ether resins, polyphenylene sulfide resins, and mixtures of two or more thereof. However, it is not limited to these.

  Among these, polyolefin-based resins, polyamide-based resins, polyester-based resins, polyacetal-based resins, and the like are more preferable resins from the viewpoint of handleability and cost, and polyamide-based resins are particularly preferable.

  A preferred polyolefin-based resin as the thermoplastic resin is a polymer obtained by polymerizing olefins (for example, α-olefins) or alkenes as monomer units. Specific examples of the polyolefin resin include ethylene (co) polymers such as low density polyethylene (for example, linear low density polyethylene), high density polyethylene, ultra low density polyethylene, ultra high molecular weight polyethylene, polypropylene, ethylene, and the like. -Propylene copolymers, polypropylene-based (co) polymers exemplified by ethylene-propylene-diene copolymers, ethylene-acrylic acid copolymers, ethylene-methyl methacrylate copolymers, ethylene-glycidyl methacrylate copolymers Examples include α-olefin copolymers such as ethylene, which are represented by coalescence.

  The most preferable polyolefin-based resin here includes polypropylene. In particular, polypropylene having a melt mass flow rate (MFR) measured at 230 ° C. and a load of 21.2 N in accordance with ISO 1133 is 3 g / 10 min or more and 30 g / 10 min or less is preferable. The lower limit value of MFR is more preferably 5 g / 10 minutes, still more preferably 6 g / 10 minutes, and most preferably 8 g / 10 minutes. Further, the upper limit is more preferably 25 g / 10 minutes, still more preferably 20 g / 10 minutes, and most preferably 18 g / 10 minutes. It is desirable that the MFR does not exceed the upper limit from the viewpoint of improving the toughness of the composition, and it is desirable that the MFR does not fall below the lower limit from the viewpoint of the fluidity of the composition.

  Moreover, in order to improve the affinity with cellulose, an acid-modified polyolefin resin can also be suitably used. The acid in this case can be appropriately selected from maleic acid, fumaric acid, succinic acid, phthalic acid and anhydrides thereof, and polycarboxylic acids such as citric acid. Among these, maleic acid or an anhydride thereof is preferable because it easily increases the modification rate. There are no particular restrictions on the modification method, but a method of melting and kneading by heating above the melting point in the presence / absence of peroxide is common. As the polyolefin resin to be acid-modified, all of the above-mentioned polyolefin resins can be used, but polypropylene can be preferably used. The acid-modified polypropylene may be used alone, but is more preferably used by mixing with unmodified polypropylene in order to adjust the modification rate of the composition. In this case, the ratio of the acid-modified polypropylene to all the polypropylenes is 0.5% by mass to 50% by mass. A more preferred lower limit is 1% by mass, still more preferably 2% by mass, still more preferably 3% by mass, particularly preferably 4% by mass, and most preferably 5% by mass. A more preferred upper limit is 45% by mass, still more preferably 40% by mass, still more preferably 35% by mass, particularly preferably 30% by mass, and most preferably 20% by mass. In order to maintain the interfacial strength with cellulose, the lower limit is preferable, and in order to maintain the ductility as a resin, the upper limit is preferable.

  The preferred melt mass flow rate (MFR) of acid-modified polypropylene measured at 230 ° C. under a load of 21.2 N in accordance with ISO 1133 is 50 g / 10 min or more in order to increase the affinity with the cellulose interface. It is preferable. A more preferred lower limit is 100 g / 10 minutes, even more preferred is 150 g / 10 minutes, and most preferred is 200 g / 10 minutes. Although an upper limit is not specifically limited, A preferable upper limit is 500 g / 10min from maintenance of mechanical strength. By setting the MFR within this range, it is possible to enjoy the advantage that the acid-modified polypropylene tends to exist at the interface between the cellulose and the resin.

  Examples of preferred polyamide resins as thermoplastic resins include polyamide 6, polyamide 11, polyamide 12 obtained by polycondensation reaction of lactams, 1,6-hexanediamine, 2-methyl-1,5-pentanediamine, 1,7-heptanediamine, 2-methyl-1-6-hexanediamine, 1,8-octanediamine, 2-methyl-1,7-heptanediamine, 1,9-nonanediamine, 2-methyl-1,8- Diamines such as octanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, m-xylylenediamine, butanedioic acid, pentanedioic acid, hexanedioic acid, heptanedioic acid , Octanedioic acid, nonanedioic acid, decanedioic acid, benzene-1,2-dicarboxylic acid, benzene-1,3-di Polyamide 6,6, polyamide 6,10 obtained as a copolymer with dicarboxylic acids such as rubonic acid, benzene-1,4-dicarboxylic acid, cyclohexane-1,3-dicarboxylic acid, cyclohexane-1,4-dicarboxylic acid, Polyamide 6,11, 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, And copolymers obtained by copolymerizing them, and examples thereof include polyamide 6, T / 6, and I copolymers.

  Among these polyamide-based resins, aliphatic polyamides such as polyamide 6, polyamide 11, polyamide 12, polyamide 6,6, polyamide 6,10, polyamide 6,11, polyamide 6,12, polyamide 6, C, polyamide 2M5, C The alicyclic polyamide is more preferable, and polyamide 6 and polyamide 6,6 are particularly preferable.

  Polyester resins preferred as the thermoplastic resin in the present invention include polyethylene terephthalate (hereinafter sometimes simply referred to as PET), polybutylene succinate (polyester resin comprising an aliphatic polyvalent carboxylic acid and an aliphatic polyol (hereinafter referred to as “polyester resin”). , Unit PBS), polybutylene succinate adipate (hereinafter also simply referred to as PBSA), polybutylene adipate terephthalate (hereinafter also simply referred to as PBAT), polyhydroxyalkanoic acid (3- Polyester resin comprising hydroxyalkanoic acid (hereinafter sometimes referred to simply as PHA), polylactic acid (hereinafter sometimes simply referred to as PLA), polybutylene terephthalate (hereinafter sometimes simply referred to as PBT), polyethylene naphtha Les 1 type or 2 or more types selected from the following (hereinafter also simply referred to as PEN), polyarylate (hereinafter also simply referred to as PAR), polycarbonate (hereinafter also simply referred to as PC), etc. Can be used.

  Among these, more preferable polyester-based resins include PET, PBS, PBSA, PBT, and PEN, and more preferably, PBS, PBSA, and PBT.

  The polyacetal resins preferable as the thermoplastic resin in the present invention are generally homopolyacetals using formaldehyde as a raw material and copolyacetals containing trioxane as a main monomer and 1,3-dioxolane as a comonomer component, and both are used. Although possible, copolyacetal can be preferably used from the viewpoint of thermal stability during processing. In particular, the amount of comonomer component (for example, 1,3-dioxolane) is more preferably in the range of 0.01 to 4 mol%. A preferred lower limit of the comonomer component amount is 0.05 mol%, more preferably 0.1 mol%, and even more preferably 0.2 mol%. Moreover, a preferable upper limit is 3.5 mol%, More preferably, it is 3.0 mol%, Still more preferably, it is 2.5 mol%, Most preferably, it is 2.3 mol%.

  From the viewpoint of thermal stability during extrusion or molding, the lower limit is preferably within the above range, and from the viewpoint of mechanical strength, the upper limit is preferably within the above range.

  In this invention, it is desirable that the ratio (pellet ratio) of the thermoplastic resin in the form of pellets exceeds 50% by mass in 100% by mass of the thermoplastic resin combined with cellulose in the first step. The lower limit of the pellet ratio is more preferably 70% by mass, even more preferably 80% by mass, particularly preferably 90% by mass, and most preferably 100% by mass (ie, substantially all of them are in the form of pellets). . In order to suppress the aggregation of the cellulose when the resin cellulose dispersion is heated with stirring in the second step to remove the dispersion medium, it is desirable to increase the pellet ratio within the above range.

(cellulose)
Next, any cellulose may be used in the present invention, but fine cellulose is desirable for fine dispersion in the resin composition. More specifically, the cellulose is more preferably cellulose fiber, cellulose whisker, or a mixture thereof.

  In the present disclosure, “length” (L) and “diameter” (D) of cellulose correspond to, for example, a long diameter and a short diameter in cellulose whiskers, and a fiber length and a fiber diameter in cellulose fibers, respectively. As the cellulose whisker and the cellulose fiber, those having a diameter of nanometer size (that is, less than 1 μm) are preferable from the viewpoint of effectively improving the extensional viscosity. Each of the cellulose whiskers and cellulose fibers that can be suitably used in the present invention has a diameter of 500 nm or less. The upper limit of the preferred cellulose diameter is 450 nm, more preferably 400 nm, still more preferably 350 nm, and most preferably 300 nm.

  In a particularly preferred embodiment, the diameter of the cellulose whisker is preferably 20 nm or more, more preferably 30 nm or more, preferably 500 nm or less, more preferably 450 nm or less, still more preferably 400 nm or less, even more preferably 350 nm or less, Most preferably, it is 300 nm or less.

  In a particularly preferred embodiment, the diameter of the cellulose fiber 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 20 nm or more. It is preferably 450 nm or less, more preferably 400 nm or less, still more preferably 350 nm or less, still more preferably 300 nm or less, and most preferably 250 nm or less.

  In order to effectively improve the extensional viscosity of the resin composition, it is desirable that the cellulose diameter is within the above-mentioned range.

  The cellulose whisker in the present invention refers to crystalline cellulose remaining after dissolving an amorphous part of cellulose in an acid such as hydrochloric acid or sulfuric acid after pulp or the like is cut as a raw material.

  Cellulose fibers were treated with hot water at 100 ° C. or higher to hydrolyze the hemicellulose part, and then fragile, and then defibrated by a high-pressure homogenizer, microfluidizer, ball mill, or disk mill. Cellulose and cellulose fiber defibrated by the TEMPO oxidation method or chemical modification of cellulose fiber hydroxyl group in an organic solvent instead of strong mechanical defibration such as pulverization are included.

  The preferred length / diameter ratio (L / D ratio) of the cellulose whiskers is less than 30. The L / D upper limit of the cellulose whisker is preferably 25, more preferably 20, still more preferably 15, still more preferably 10, and most preferably 5. Although a minimum is not specifically limited, What is necessary is just to exceed one. In order to impart appropriate fluidity to the resin composition, it is desirable that the L / D ratio of the cellulose whisker is within the above range.

  The L / D lower limit of the cellulose fiber is preferably 30, more preferably 50, more preferably 80, still more preferably 100, particularly preferably 120, and most preferably 150. . Although an upper limit is not specifically limited, From a viewpoint which does not make melt viscosity of a resin composition too high, Preferably it is 1000 or less.

  In the present disclosure, the length, diameter, and L / D ratio of each of the cellulose whisker and the cellulose fiber are determined based on the water dispersion of each of the cellulose whisker and the cellulose fiber by using a high shear homogenizer (for example, manufactured by Nippon Seiki Co., Ltd. The name “Excel Auto Homogenizer ED-7”) was used, and the treatment condition: a water dispersion dispersed at a rotational speed of 15,000 rpm × 5 minutes was diluted with pure water to 0.1 to 0.5% by mass, and mica It is obtained by measuring with a high-resolution scanning microscope (SEM) or an atomic force microscope (AFM) using the sample cast above and air-dried as a measurement sample. Specifically, the length (L) and diameter (D) and ratio (ratio) of 100 celluloses randomly selected in an observation field whose magnification was adjusted so that at least 100 celluloses were observed. This can be confirmed by calculating (L / D). The length and diameter of the cellulose of the present disclosure are the number average value of a total of 100 celluloses. For each of the cellulose whiskers and cellulose fibers, 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, and the cellulose whisker of the present disclosure And the length, diameter, and L / D ratio of each of the cellulose fibers. In the present disclosure, cellulose whiskers and cellulose fibers can also be distinguished from each other by classifying cellulose whiskers having a ratio (L / D) of less than 30 as cellulose whiskers and cellulose fibers having 30 or more ratios.

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

  Alternatively, the length, diameter, and L / D ratio of each of the cellulose whiskers and cellulose fibers in the composition are obtained by dissolving the resin component in the composition in an organic or inorganic solvent that can dissolve the resin component in the composition. After separating the cellulose and thoroughly washing with the solvent, an aqueous dispersion in which the solvent is replaced with pure water is prepared, diluted with pure water so that the cellulose concentration becomes 0.1 to 0.5% by mass, It can confirm by measuring on the above-mentioned measuring method by using what was cast on mica and air-dried as a measurement sample. At this time, the cellulose to be measured is measured with a total of 200 or more randomly selected 100 or more cellulose fibers having an L / D of 30 or more and 100 or more cellulose whiskers with an L / D of less than 30.

  The cellulose whisker that can be suitably used in the present invention is a cellulose whisker having a crystallinity of 55% or more. When the crystallinity is in this range, the mechanical properties (strength and dimensional stability) of the cellulose whisker itself increase, and therefore, when dispersed in the resin, the strength and dimensional stability of the resin composition tend to increase.

  The crystallinity of the cellulose whiskers is preferably 60% or more, and the lower limit of the more preferable crystallinity is 65%, still more preferably 70%, and most preferably 80%. The higher the degree of crystallinity of cellulose whiskers, the better. Therefore, the upper limit is not particularly limited, but 99% is a preferable upper limit from the viewpoint of production.

  As the cellulose fiber, a cellulose fiber having a crystallinity of 55% or more can be preferably used. When the crystallinity is within this range, the mechanical properties (strength and dimensional stability) of the cellulose fiber itself are increased, and therefore the strength and dimensional stability of the resin composition tend to increase when dispersed in the resin. A more preferred lower limit of crystallinity is 60%, even more preferred is 70%, and most preferred is 80%. The upper limit of the crystallinity of the cellulose fiber is not particularly limited and is preferably as high as possible. However, the preferable upper limit is 99% from the viewpoint of production.

  The degree of crystallinity of cellulose whiskers and cellulose fibers depends on the degree of removal of amorphous parts during the production of these celluloses, but removal of impurities such as lignin under production conditions where the degree of removal of amorphous parts is high The degree is also increased. If there is a large amount of residual impurities such as lignin, discoloration may be caused by heat during processing of the resin composition. From the viewpoint of suppressing discoloration of the resin composition during extrusion processing and molding processing, cellulose whiskers and The crystallinity of the cellulose fiber is preferably within the above range.

The crystallinity here refers to the Segal from the diffraction pattern (2θ / deg. Is 10 to 30) when the sample is measured by wide-angle X-ray diffraction when the cellulose is a cellulose type I crystal (derived from natural cellulose). According to the law, the following formula is obtained.
Crystallinity (%) = ([Diffraction intensity due to (200) plane of 2θ / deg. = 22.5] − [Diffraction intensity due to amorphous of 2θ / deg. = 18]) / [2θ / Deg. = Diffraction intensity due to (200) plane of 22.5] × 100
In addition, when the cellulose is a cellulose type II crystal (derived from regenerated cellulose), the crystallinity is 2θ = 12.6 ° attributed to the (110) plane peak of the cellulose type II crystal in wide-angle X-ray diffraction. From the absolute peak intensity h0 and the peak intensity h1 from the base line at this surface interval, it is obtained by the following equation.
Crystallinity (%) = h1 / h0 × 100

  As the crystal form of cellulose, type I, type II, type III, type IV and the like are known. Type I and type II cellulose are widely used, while type III and type IV cellulose are laboratory scales. However, it is not widely used on the industrial scale. As the cellulose used in the present invention, a resin composite having a relatively high structural mobility, a lower linear expansion coefficient by dispersing the cellulose in a resin, and a superior strength and elongation during tensile and bending deformation. Since it is obtained, cellulose containing cellulose type I crystals or cellulose type II crystals is preferable, and cellulose containing cellulose type I crystals and having a crystallinity of 55% or more is more preferable.

  The degree of polymerization of the cellulose whisker is preferably 100 or more, more preferably 150 or more, preferably 300 or less, more preferably 250 or less. The degree of polymerization of the cellulose fiber is preferably 400 or more, more preferably 450 or more, preferably 2500 or less, more preferably 2000 or less. From the viewpoint of processability in extrusion molding and the development of mechanical properties of the molded article, it is preferable that the degree of polymerization of cellulose whiskers and cellulose fibers is not too high, and it is desirable that the degree of polymerization of the mechanical properties is not too low.

  The degree of polymerization of cellulose whiskers and cellulose fibers is the average degree of polymerization measured according to the reduced specific viscosity method using a copper ethylenediamine solution described in the confirmation test (3) of “15th revised Japanese Pharmacopoeia Manual (published by Yodogawa Shoten)” Means.

  Examples of a method for controlling the degree of polymerization of cellulose (that is, the average degree of polymerization) include hydrolysis treatment. 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 process removes impurities such as hemicellulose and lignin in addition to the above-described amorphous cellulose, so that the inside of the fiber becomes porous. Thereby, in the process of giving mechanical shearing, such as an extrusion process described later, the cellulose component is easily subjected to mechanical treatment, and the cellulose component is easily refined.

  The method for hydrolysis is not particularly limited, and examples thereof include acid hydrolysis, alkaline hydrolysis, hydrothermal decomposition, steam explosion, and microwave decomposition. These methods may be used alone or in combination of two or more. In the acid hydrolysis method, for example, α-cellulose obtained as a pulp from a fibrous plant is used as a cellulose raw material, and this is dispersed in an aqueous medium, and an appropriate amount of proton acid, carboxylic acid, Lewis acid, heteropoly acid, etc. In addition, the average degree of polymerization can be easily controlled by heating while stirring. The reaction conditions such as temperature, pressure, and time at this time vary depending on the cellulose species, cellulose concentration, acid species, and acid concentration, but are appropriately adjusted to achieve the desired average degree of polymerization. For example, the conditions of using 2 mass% or less mineral acid aqueous solution and processing a cellulose for 10 minutes or more under 100 degreeC or more and pressurization are mentioned. Under these conditions, a catalyst component such as an acid penetrates into the inside of the cellulose fiber, the hydrolysis is accelerated, the amount of the catalyst component to be used is reduced, and subsequent purification is facilitated. In addition, the dispersion liquid of the cellulose raw material at the time of hydrolysis may contain a small amount of an organic solvent in a range not impairing the effects of the present invention, in addition to water.

(Dispersion medium)
The dispersion medium in the cellulose dispersion in the present invention is a dispersion medium containing water as a main component. Here, water as a main component is a state in which the proportion of water in the dispersion medium is 50% by mass or more. Examples of the dispersion medium other than water include organic solvents that are compatible with water, organic solvents that are incompatible with water, and surfactants.

  The organic solvent compatible with water includes not only an organic solvent miscible with water in all composition ranges but also an organic solvent miscible with a specific composition range. Specific examples include methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, ethylene glycol, tetrahydrofuran, acetone, methyl ethyl ketone, acetonitrile, dimethylformamide, triethylamine, pyridine, dimethyl sulfoxide, acetic acid, and the like. It is not limited.

  Moreover, the organic solvent incompatible with water refers to an organic solvent having a solubility in water of 1% by mass or less and hardly dissolving. Specific examples include, but are not limited to, ethyl acetate, dichloromethane, chloroform, carbon tetrachloride, toluene, xylene, cyclohexane, pentane, heptane and the like.

  Furthermore, as the surfactant, any of an anionic surfactant, a nonionic surfactant, an amphoteric surfactant, and a cationic surfactant can be used. In this respect, anionic surfactants and nonionic surfactants are preferred, and nonionic surfactants are more preferred.

  Examples of the anionic surfactant include fatty acid sodium (fatty acid) such as fatty acid sodium, fatty acid potassium, and sodium alphasulfo fatty acid ester, and linear alkylbenzene series such as sodium linear alkylbenzene sulfonate. Examples of alcohols (anions) include sodium alkyl sulfates and sodium alkyl ether sulfates. Examples of alpha olefins include sodium alpha olefin sulfonates. Examples of normal paraffins include sodium alkyl sulfonates. It is also possible to use seeds or a mixture of two or more.

  Examples of nonionic surfactants include fatty acids (nonionic), glycolipids such as sucrose fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, fatty acid alkanolamides, and the like. Examples of the ion) include polyoxyethylene alkyl ethers and the like, and examples of the alkylphenol type include polyoxyethylene alkyl phenyl ethers. These may be used alone or in combination.

  Examples of the zwitterionic surfactant include alkylamino fatty acid sodium and the like as the amino acid type, alkyl betaine and the like as the betaine type, alkylamine oxide and the like as the amine oxide type, and one or two of them. It is also possible to mix and use seeds or more.

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

  The surfactant may be a fat or oil derivative. As fats and oils, esters of fatty acids and glycerin can be mentioned, which usually means triglyceride (tri-O-acylglycerin). It is classified as dry oil, semi-dry oil, non-dry oil in the order that it is easily solidified by oxidation with fatty oil, and can be used for various uses such as edible and industrial, for example, One type or two or more types can be used in combination.

  As fats and oils, for example, terpin oil, tall oil, rosin, white squeezed oil, corn oil, soybean oil, sesame oil, rapeseed oil (canola oil), rice oil, coconut oil, coconut oil, safflower oil (safflower oil) , Palm oil (palm kernel oil), cottonseed oil, sunflower oil, sesame oil (pepper oil), flaxseed oil, olive oil, peanut oil, almond oil, avocado oil, hazelnut oil, walnut oil, grape seed oil, mustard oil, Lettuce oil, fish oil, whale oil, coconut oil, liver oil, cocoa butter, peanut butter, palm oil, lard Ghee, etc.), hydrogenated oil (margarine, shortening, etc.), castor oil (vegetable oil) and the like.

  In a particularly preferred embodiment, the surfactant is at least one selected from the group consisting of rosin derivatives, alkylphenyl derivatives, bisphenol A derivatives, β-naphthyl derivatives, styrenated phenyl derivatives, and hardened castor oil derivatives.

(Preparation of resin cellulose dispersion)
In the first step, the resin cellulose dispersion is prepared by preparing a cellulose dispersion in which cellulose is dispersed in a dispersion medium containing water as a main component and adding the cellulose dispersion to the thermoplastic resin. It is preferable. The dispersibility of cellulose in the dispersion medium affects the physical property stability of the molded product as the final product. The above method has an advantage that the dispersibility of cellulose in the dispersion medium can be easily grasped and managed, and as a result, the cellulose diameter in the resin cellulose dispersion can be stabilized.

  Cellulose dispersions in which cellulose is dispersed in a dispersion medium containing water as a main component can be obtained by various methods. For example, the raw material pulp is treated with hot water at 100 ° C. or higher, and the hemicellulose part is hydrolyzed and weakened, and then pulverized by a high-pressure homogenizer, microfluidizer, ball mill, or disk mill. Method of defibration, cutting raw material pulp, etc., dissolving amorphous part of cellulose in acid such as hydrochloric acid or sulfuric acid, neutralizing method, pulverizing raw material pulp, hot water at 100 ° C or higher, etc. For example, the pulp obtained by treating and dewatering with a stirrer is stirred with a stirrer, and then subjected to defibration modification with a bead mill or the like in an atmosphere of an organic solvent, and then the solvent is replaced with water.

  In addition, the cellulose dispersion prepared as described above is dried under shearing conditions and obtained as powdered cellulose, and then blended to obtain a desired cellulose concentration, together with a dispersion medium, a high-pressure homogenizer, a microfluidizer, A method of applying shear and redispersing under the apparatus conditions for applying shear such as a ball mill and a disk mill can also be used suitably.

  Next, the resin cellulose dispersion can be obtained by adding the cellulose dispersion to the thermoplastic resin. As an addition method, the thermoplastic resin is supplied to the extruder in the form of pellets, powders, etc. (preferably the pellet ratio exceeds 50 mass%), and then the cellulose dispersion is added to the thermoplastic resin under shearing conditions. And a method of kneading to obtain a resin cellulose dispersion.

  The preferable composition of the resin cellulose dispersion obtained in the first step is 1 to 70 parts by mass of cellulose and 1 to 150 parts by mass of the dispersion medium with respect to 100 parts by mass of the thermoplastic resin. The lower limit of the amount of cellulose relative to 100 parts by mass of the thermoplastic resin is more preferably 2 parts by mass, still more preferably 3 parts by mass, and particularly preferably 4 parts by mass. The upper limit of the amount of cellulose is more preferably 60 parts by mass, still more preferably 50 parts by mass, particularly preferably 45 parts by mass, and most preferably 30 parts by mass. In order to improve the dispersibility of the cellulose in the resin composition obtained and to improve the physical property stability of the molded article, the above range is desired. The lower limit amount of the dispersion medium is more preferably 5 parts by mass, still more preferably 10 parts by mass, still more preferably 15 parts by mass, and most preferably 20 parts by mass. The upper limit amount of the dispersion medium is more preferably 130 parts by mass, still more preferably 120 parts by mass, still more preferably 110 parts by mass, and most preferably 100 parts by mass.

≪Second process≫
In this production method, a second step, which is carried out subsequent to the first step, is necessary to obtain a resin cellulose mixture by heating the resin cellulose dispersion while stirring to remove the dispersion medium.

  It is known that cellulose is finely dispersed stably in a dispersion. In the second step, the resin cellulose dispersion is heated with stirring to remove the dispersion medium, so that the cellulose can be heated while being rubbed with the resin to remove the dispersion medium. Aggregation of cellulose due to removal can be significantly suppressed, and the dispersibility of cellulose in the resulting resin composition can be enhanced. The second step is therefore very important.

  As described above, the second step has a role of removing the dispersion medium mainly composed of water while shearing the resin cellulose dispersion. Since the dispersion medium contains water as a main component, the heating temperature in the second step is desirably 100 ° C. or higher and lower than 200 ° C. The upper limit is more preferably 180 ° C, still more preferably 170 ° C, still more preferably 160 ° C, and most preferably 150 ° C. The lower limit is more preferably 105 ° C, even more preferably 110 ° C, and most preferably 115 ° C. Moreover, when the thermoplastic resin to be used is a crystalline resin, the upper limit temperature is desirably equal to or lower than the melting point thereof. In addition, the heating temperature in the second step is gradually increased within the above-described temperature range, for example, 100 ° C.-120 ° C.-150 ° C.-180 ° C. (that is, having a temporal temperature gradient). Is preferable from the viewpoint of suppressing aggregation of cellulose.

≪Third process≫
In this invention, it is necessary to provide the 3rd process of melt-kneading the cellulose resin mixture obtained at the 2nd process following the 2nd process.

  The temperature of the third step is set depending on the types of the thermoplastic resin and cellulose, but is higher than the temperature at which the thermoplastic resin can be melt-kneaded and lower than the thermal decomposition start temperature of the thermoplastic resin and cellulose. desirable.

  In the third step, it is more preferable that a part of the step is in a reduced pressure state less than atmospheric pressure to remove volatile components and water vapor from the resin kneaded product.

  In a particularly preferred embodiment of the present invention, the first to third steps are carried out continuously with an extruder. Usable extruders include single screw extruders, twin screw extruders, and multi-screw extruders. Among these, a twin screw extruder can be preferably used. Furthermore, among the twin screw extruders, a twin screw extruder having a long stroke in which L / D obtained by dividing the cylinder length (L) by the screw diameter (D) is 40 or more can be more preferably used. Furthermore, an extruder having a structure in which a plurality of vent ports capable of removing the dispersion medium can be installed at the upper part of the extruder can be most preferably used.

  By carrying out the first step in the extruder, it becomes possible to remove water in the dispersion medium almost instantaneously while giving strong shear to the friction between the cellulose and the resin (preferably pellets). In addition, it is possible to develop a cellulose dispersibility that is high enough to improve the physical property stability of the obtained molded body, and furthermore, since all the steps can be performed in one process, it is possible to achieve an economic advantage. .

  The preferable ratio of the thermoplastic resin in the resin composition obtained by the production method of the present invention is 40 to 99% by mass. The lower limit amount is more preferably 50% by mass, still more preferably 60% by mass, still more preferably 70% by mass, particularly preferably 80% by mass, and most preferably 90% by mass. The upper limit amount is more preferably 98% by mass, and most preferably 97% by mass.

  Moreover, in this invention, you may add an additional component as needed in the range which does not impair the effect of this invention other than an above-described component. The addition amount of these additional components is desirably in a range not exceeding 15 parts by mass when the total amount of the resin composition is 100 parts by mass.

  Examples of additional components include additional thermoplastic resins, inorganic fillers (talc, kaolin, zonotlite, wollastonite, potassium titanate, glass fibers, etc.), known for increasing the affinity between the inorganic filler and the resin. Silane coupling agents, flame retardants (halogenated resins, silicone flame retardants, magnesium hydroxide, aluminum hydroxide, organic phosphate compounds, ammonium polyphosphate, red phosphorus, etc.), fluorine-based polymers exhibiting dripping prevention effects, Plasticizers (oil, low molecular weight polyolefin, polyethylene glycol, fatty acid esters, etc.), flame retardant aids such as antimony trioxide, colorants such as carbon black for coloring, antistatic agents, various peroxides, antioxidants, An ultraviolet absorber, a light stabilizer, etc. are mentioned.

  The production method of the present invention can highly disperse cellulose in a thermoplastic resin, so that the elongation viscosity of the resulting resin composition can be improved and can be used for a material that is stretched in a molten state. . Specifically, it can be suitably used for various large-size component applications formed by large-size sheet molding, blow molding, vacuum molding, inflation molding, and the like. Of course, even in ordinary injection-molded products, stable physical properties can be obtained due to the high dispersibility of cellulose, so it can be used for automobile exterior materials, structural members such as chassis, interior members, and drive members such as gears that require reliability. It can be suitably used.

  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]
Below, the used raw material and the evaluation method are demonstrated.
≪Thermoplastic resin≫
Polyamide Polyamide 6 (hereinafter simply referred to as PA)
“UBE nylon 1013B” available from Ube Industries, Ltd.

≪Evaluation method≫
<Polymerization degree of cellulose>
It was measured by a reduced specific viscosity method using a copper ethylenediamine solution specified in the crystalline cellulose confirmation test (3) of “14th revised Japanese pharmacopoeia” (published by Yodogawa Shoten).

<Crystal form and crystallinity of cellulose>
Using an X-ray diffractometer (manufactured by Rigaku Corporation, multipurpose X-ray diffractometer), a diffraction image was measured by a powder method (at room temperature), and a crystallinity was calculated by a Segal method. The crystal form was also measured from the obtained X-ray diffraction image.

<L / D of cellulose>
Cellulose was 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”, treatment condition: 15,000 rpm × 5 minutes) The dispersed aqueous dispersion was diluted with pure water to 0.1 to 0.5% by mass, cast on mica and air-dried, and the particle image was observed with an atomic force microscope (AFM). The major axis (L) and minor axis (D) of the particle image were measured, and the ratio (L / D) was obtained from these values, and calculated as the average value of 100 to 150 particles.

<Average diameter of cellulose>
In a planetary mixer (trade name “5DM-03-R”, manufactured by Shinagawa Kogyo Co., Ltd., stirring blade is a hook type) with a solid content of 40% by mass, kneading is performed at 126 rpm at room temperature and normal pressure for 30 minutes. did. Subsequently, it was made into a pure water suspension with a concentration of solid content of 0.5% by mass, and a high shear homogenizer (manufactured by Nippon Seiki Co., Ltd., trade name “Excel Auto Homogenizer ED-7”, treatment condition: 15,000 rpm × rotation speed) 5 minutes), and centrifuged (manufactured by Kubota Shoji Co., Ltd., trade name “6800 type centrifuge”, rotor type RA-400 type, treatment condition: collected supernatant centrifuged for 10 minutes at a centrifugal force of 39200 m2 / s. Further, the supernatant was centrifuged at 116000 m2 / s for 45 minutes.) Volume obtained by laser diffraction / scattering particle size distribution analyzer (manufactured by Horiba, Ltd., trade name “LA-910”, ultrasonic treatment for 1 minute, refractive index 1.20) using the supernatant after centrifugation. An integrated 50% particle diameter (volume average particle diameter) in the frequency particle size distribution was measured, and this value was defined as the average diameter.

<Cellulose dispersibility>
After the resin composition pellet is injection-molded into the shape of an ISO multi-purpose test piece, the central portion of the molded piece is subjected to an X-ray tube voltage of 40 kV and a tube using a high-resolution 3DX X-ray microscope (nano3DX: manufactured by Rigaku Corporation). CT measurement was performed under the condition of current of 30 mA and 600 cubic μm at the center of the molded piece. The number of projections was 1000, and the exposure time was 24 seconds per sheet. The spatial resolution at this time was 0.54 μm / pixel. The obtained data was binarized by the Otsu method, and the volume detected as an object in the composition was divided by the total volume to calculate the amount of foreign matter. In this case, if 10% by volume of cellulose is blended and half of the cellulose is present in the composition as an aggregate having a spatial resolution or higher, 5% by volume is calculated as a foreign substance.

<Coefficient of variation of tensile strength at break>
Using a multi-purpose test piece conforming to ISO 294-3, the tensile fracture strength is measured by n number 15 according to ISO 527, and the coefficient of variation (CV) is calculated based on the following formula based on the obtained data. did.
CV = (σ / μ) × 100
Here, σ represents a standard deviation, and μ represents an arithmetic average of tensile rupture strength.

<Defect rate of fender>
A predetermined mold (cavity) capable of molding a fender having the shape shown in the schematic diagram of FIG. 1 by setting the cylinder temperature of an injection molding machine having a maximum clamping pressure of 4000 tons to 250 ° C. using the resin composition pellets. Volume: about 1400 cm ³ , average thickness: 2 mm, projected area: about 7000 cm ² , number of gates: 5-point gate, hot runner: In FIG. 1, a runner (hot runner) is used to clarify the runner position of the molded body. The relative position 1 of () was illustrated.), The mold temperature was set to 60 ° C., and 20 fenders were molded.
The obtained fender was placed on the floor, and a bag containing 5 kg of sand was dropped from the height of about 50 cm onto the center of the fender, and the destruction state of the fender was confirmed. The number of sheets destroyed out of 20 was counted.

≪Extruder configuration≫
A liquid injection nozzle is installed in cylinder 3 of a twin-screw extruder (STEMER OMEGA30H, L / D = 60) having 13 cylinder blocks, cylinder 1 is water-cooled, cylinders 2-4 are 80 ° C., and cylinder 5 is The temperature was set at 100 ° C, the cylinder 6 at 130 ° C, the cylinder 7 at 230 ° C, the cylinders 8 to 13 and the die at 250 ° C.

  As a screw configuration, the cylinders 1 to 4 are configured as a transport zone composed of only a transport screw, and three clockwise kneading disks (feed type kneading disks: hereinafter simply referred to as RKD) are respectively connected to the cylinders 5 and 6 from the upstream side. In addition, a vent port was installed in the upper part of the extruder so that the dispersion medium could be removed. Subsequently, three RKD, two neutral kneading discs (non-conveying type kneading disc: hereinafter may be simply referred to as NKD), one counterclockwise kneading disc from cylinders 7 to 8 (Reverse feed type kneading disc: hereinafter simply referred to as LKD) was continuously arranged to form a melting zone. The cylinder 9 was used as a transport zone, and one RKD, two NKDs, and one LKD were continuously arranged in this order in the cylinder 10 to form a melting zone, and then cylinders 11 to 13 were used as a transport zone. Here, vacuum suction was possible with the cylinder 12.

Each step of the present invention in this extruder configuration is described below to aid understanding.
For example, when a thermoplastic resin is supplied from the cylinder 1 and a cellulose dispersion is added from the cylinder 3, the cylinders 3 and 4 after the addition of the dispersion are the first step in the present invention. Further, the cylinders 5 and 6 serve to remove the dispersion medium while stirring, which is the second step in the present invention. Further, the cylinder 8 and subsequent zones are zones for melting and kneading the resin cellulose mixture, which is the third step in the present invention.

[Preparation Example 1] Preparation of Cellulose Fiber Dispersion After cutting linter pulp, using autoclave, heated in hot water at 120 ° C or higher for 3 hours, squeezed purified pulp from which hemicellulose portion was removed, and purified water After the fiber is highly shortened and fibrillated by beating so that the solid content is 1.5% by weight, the fiber is defibrated with a high-pressure homogenizer (operating pressure: 10 times at 85 MPa) at the same concentration. As a result, defibrated cellulose was obtained. Here, in the beating process, a disc refiner is used, and a beating blade having a high defibrating function (hereinafter referred to as a defibrating blade) is used after processing for 4 hours with a beating blade having a high cutting function (hereinafter referred to as a cutting blade). Further, beating was performed for 1.5 hours to obtain cellulose fibers. The properties of the obtained cellulose fibers were evaluated by the above-described method. The results are shown below.
L / D = 300
Average fiber diameter = 90 nm
Crystallinity = 80%
Degree of polymerization = 600
The obtained cellulose fiber dispersion was subjected to centrifugal filtration to obtain a dispersion having a solid content (cellulose) ratio of 5% by weight.

[Preparation Example 2] Preparation of cellulose whisker dispersion Commercially available DP pulp (average polymerization degree 1600) was cut and hydrolyzed in a 10% hydrochloric acid aqueous solution at 105 ° C for 30 minutes. The obtained acid-insoluble residue was filtered, washed, and pH adjusted to prepare a cellulose whisker dispersion having a solid concentration of 14% by weight and pH 6.5. The characteristics of the obtained cellulose whiskers were evaluated by the above-described method. The results are shown below.
L / D = 1.6
Average diameter = 200nm
Crystallinity = 78%
Degree of polymerization = 200

[Preparation Example 3] Preparation of Cellulose Whisker Surfactant Dispersion For 100 parts by mass of the cellulose whisker dispersion prepared in Preparation Example 2, polyoxyethylene hydrogenated castor oil ether (Aoki oil or fat) as a surfactant as a dispersion medium other than water. 4 parts by mass of Braunon RCW-20 manufactured by Kogyo Co., Ltd. was added and stirred to prepare a cellulose whisker surfactant dispersion. The characteristics of cellulose whiskers are the same as in Preparation Example 2.

[Preparation Example 4] Preparation of PA powder PA pellets were freeze-ground using a Linlex mill while cooling with liquid nitrogen to obtain a PA powder having an average particle size of about 200 µm.

[Example 1]
<Step 1> Step of preparing resin cellulose dispersion To 100 parts by mass of the PA powder obtained in Preparation Example 4, 110 parts by mass of the cellulose fiber dispersion obtained in Preparation Example 1 is added and mixed with a stirrer. Thus, a resin cellulose dispersion was prepared.
<Step 2> A step of heating the dispersion while stirring to remove the dispersion medium to obtain a resin cellulose mixture. The resin cellulose dispersion in Step 1 is mixed with a closed planetary mixer (trade name “Kodaira Seisakusho Co., Ltd. ACM-5LVT "(stirring blade is hook type), after stirring at 70 rpm for 80 minutes at 25 ° C and atmospheric pressure, set a warm bath at 60 ° C under reduced pressure of -0.1 MPa, and at 307 rpm for 5 hours Then, drying under reduced pressure was performed to obtain a resin cellulose mixture.
<Step 3> Step of melt-kneading the resin cellulose mixture The resin cellulose mixture is supplied in an amount of 15 kg / h from the cylinder 1 of the extruder, melt-kneaded, and a resin composition pellet having a cellulose fiber content of 5% by mass. Got. At this time, the cellulose dispersion liquid was not added from the cylinder 3. In this case, the extruder is the third step.

[Example 2]
<Step 1> Step of Preparing Resin Cellulose Dispersion Obtained in 21 parts by mass of the cellulose fiber dispersion obtained in Preparation Example 1 and in Preparation Example 2 with respect to 100 parts by mass of the PA powder obtained in Preparation Example 4. 30 parts by weight of cellulose whiskers were added and mixed with a stirrer to prepare a resin cellulose dispersion.
<Step 2> Step of heating the dispersion while stirring to remove the dispersion medium and obtaining a cellulose resin mixture The same procedure as in Step 2 of Example 1 was performed.
<Step 3> Step of melting and kneading the resin cellulose mixture The same procedure as in Step 3 of Example 1 was performed to obtain resin composition pellets having a cellulose fiber content of 1% by mass and a cellulose whisker content of 4% by mass.

[Example 3]
<Step 1> Step of preparing resin cellulose dispersion The PA powder obtained in Preparation Example 4 is supplied at 14.3 kg / h from cylinder 1 of the extruder, and obtained in Preparation Example 1 from cylinder 3. The cellulose fiber dispersion was added in an amount of 15 kg / h, and mixed in the portions of the cylinders 3 and 4 in the extruder to prepare a resin cellulose dispersion. At this time, the rotational speed of the extruder was set to 500 rpm in order to increase the stirring efficiency.
<Step 2> A step of heating the dispersion while stirring to remove the dispersion medium to obtain a resin cellulose mixture. From the resin cellulose dispersion prepared in cylinders 3 and 4 corresponding to Step 1, corresponding to the second step. In the cylinders 5 and 6, water as a dispersion medium was removed to obtain a resin cellulose mixture. At this time, a large amount of water vapor was generated from the vent port at the top of the extruder.
<Step 3> Step of Melting and Kneading Resin Cellulose Mixture The resin cellulose mixture obtained in Step 2 is melt-kneaded after cylinder 7 corresponding to Step 3, and a resin composition pellet having a cellulose fiber content of 5% by mass. Got. At this time, the reduced pressure state was not used in this step.

[Example 4]
In Step 1, the same procedure as in Example 3 was performed except that the cellulose dispersion added from the cylinder 3 was changed to the cellulose whisker fiber dispersion 5.3 kg / h obtained in Preparation Example 2, and melt-kneading was performed. This was carried out to obtain a resin composition pellet having a cellulose whisker content of 5% by mass.

[Example 5]
In Step 1, the cellulose dispersion added from the cylinder 3 is the cellulose fiber dispersion obtained in Preparation Example 1 and the cellulose whisker obtained in Preparation Example 2. The ratio of cellulose fiber to cellulose whisker in the dispersion is Except for changing to a cellulose mixed dispersion 7.3 kg / h mixed with a stirrer so as to be 2: 8, everything was carried out in the same manner as in Example 3, melt-kneading was carried out, cellulose whisker content 1 mass%, cellulose A resin composition pellet having a whisker content of 4% by mass was obtained.

[Example 6]
The same procedure as in Example 5 was performed except that the PA added from the cylinder 1 in Step 1 was changed to a mixture of 50% by mass of PA powder and 50% by mass of PA pellets. At this time, in order to make the supply of PA uniform, two loss-in-weight feeders were quantitatively supplied.

[Example 7]
The same procedure as in Example 5 was performed except that the PA added from the cylinder 1 in Step 1 was changed to a mixture of 20% by mass of PA powder and 80% by mass of PA pellets.

[Example 8]
In step 1, everything was carried out in the same manner as in Example 5 except that the PA added from the cylinder 1 was changed to only PA pellets.

[Example 9]
In step 3, everything was carried out in the same manner as in Example 8 except that some of the cylinders 12 were in a reduced pressure state.

[Example 10]
In Step 1, the amount of PA added from the cylinder 1 is 14.1 kg / h, and the cellulose dispersion added from the cylinder 3 is 4.9 kg / h of the cellulose whisker surfactant dispersion obtained in Preparation Example 3. Except for the above, the same procedure as in Example 9 was performed.

[Comparative Example 1]
<Step A> Step of preparing a resin cellulose dispersion The 100 parts by mass of the PA powder obtained in Preparation Example 4 is mixed with 105 parts by mass of the cellulose fiber dispersion prepared in Preparation Example 1, and this is subjected to centrifugal filtration. And the resin cellulose dispersion liquid whose total amount of resin and a cellulose fiber is 60 mass% was prepared.
<Step B> Step of heating the dispersion without stirring to remove the dispersion medium and obtaining a resin cellulose mixture Using a vacuum dryer in which the resin cellulose dispersion obtained in the above step A was set at 80 ° C. And dried to obtain a dried resin cellulose fiber. Since the dried product was in a lump state, it was pulverized for 5 minutes using a Henschel mixer having a volume of 10 liters to obtain a powdery resin cellulose fiber mixture.
<Step C> Step of melt kneading the resin cellulose mixture The resin cellulose mixture obtained in the above step B is supplied from the cylinder 1 of the extruder at an amount of 15 kg / h, melt kneading is performed, and the cellulose fiber content is 5 A mass% resin composition pellet was obtained. At this time, the cellulose dispersion liquid was not added from the cylinder 3.

[Comparative Example 2]
<Step A> Step of heating the dispersion while stirring to remove the dispersion medium and obtaining cellulose fiber powder The cellulose fiber dispersion obtained in Preparation Example 1 was obtained in the same manner as in Step 2 of Example 1. In a closed planetary mixer, after stirring at 70 rpm for 80 minutes at 25 ° C. and atmospheric pressure, a 60 ° C. warm bath was set under a reduced pressure condition of −0.1 MPa, and dried under reduced pressure at 307 rpm for 5 hours. Cellulose fiber powder was obtained.
<Process B> Process of melt-kneading cellulose fiber powder and PA powder 5.100 parts by mass of PA pellets are dry blended with 5.25 parts by mass of the cellulose fiber powder obtained in the above-mentioned process A. The cylinder 1 was supplied at a rate of 15 kg / h, and melt kneading was performed to obtain a resin composition pellet having a cellulose fiber content of 5 mass%. At this time, the cellulose dispersion liquid was not added from the cylinder 3.

[Comparative Example 3]
<Step A> A step of heating the dispersion while stirring to remove the dispersion medium and obtaining a cellulose mixture powder. Obtained in Preparation Example 2 with respect to 100 parts by mass of the cellulose fiber dispersion obtained in Preparation Example 1. 143 parts by mass of the cellulose whisker dispersion was mixed and stirred with a stirrer to prepare a cellulose mixture dispersion. This dispersion was dried under reduced pressure in the same manner as in Comparative Example 2 to obtain a cellulose mixture powder.
<Step B> Step of melting and kneading cellulose mixture powder and PA pellets Dry blending 5.25 parts by mass of the cellulose mixture powder obtained in Step A above with respect to 100 parts by mass of PA pellets, and cylinders of the extruder 1 was supplied in an amount of 15 kg / h, and melt kneading was performed to obtain resin composition pellets having a cellulose content of 5 mass%. At this time, the cellulose dispersion liquid was not added from the cylinder 3.

  It was found that stirring in an extruder exhibits higher dispersibility than the planetary mixer, and the defect rate of the molded product can be greatly suppressed. Furthermore, it can be seen that the shape of the polyamide as the thermoplastic resin is more effective in suppressing the fine dispersibility and the defect rate in the molded body than the powder shape. On the other hand, good results were not obtained in any of the comparative examples in which the drying was performed without stirring or in an environment where polyamide was not present.

  The resin composition obtained by the production method of the present invention can be suitably applied to molded articles for various uses such as automobile members, electric / electronic members, office equipment housings, precision parts and the like.

Claims (12)

A method for producing a resin composition comprising a thermoplastic resin and cellulose,
A first step of preparing a resin cellulose dispersion containing a dispersion medium containing water as a main component, and a thermoplastic resin and cellulose dispersed in the dispersion medium;
A second step of heating the resin cellulose dispersion while stirring to remove the dispersion medium to obtain a resin cellulose mixture;
A third step of melt-kneading the resin cellulose mixture obtained in the second step to obtain a resin composition;
The manufacturing method of the resin composition which contains these in this order.   The manufacturing method of the resin composition of Claim 1 whose ratio of the thermoplastic resin in a resin composition is 50-99 mass% with respect to 100 mass% of resin compositions.   The thermoplastic resin is selected from the group consisting of polyolefin resins, polyamide resins, polyester resins, polyacetal resins, polyphenylene ether resins, polyphenylene sulfide resins, and mixtures of any two or more thereof. A method for producing the resin composition according to 1 or 2.   The method for producing a resin composition according to claim 3, wherein the thermoplastic resin is a polyamide-based resin.   The method for producing a resin composition according to claim 4, wherein the polyamide-based resin is polyamide 6, polyamide 6, 6, or a mixture thereof.   The manufacturing method of the resin composition as described in any one of Claims 1-5 whose cellulose is a cellulose fiber, a cellulose whisker, or a mixture thereof.   In the first step, after cellulose is dispersed in a dispersion medium to obtain a cellulose dispersion, the cellulose dispersion is added to a thermoplastic resin to obtain the resin cellulose dispersion. A method for producing the resin composition according to claim 1.   The manufacturing method of the resin composition as described in any one of Claims 1-7 whose more than 50 mass% of the thermoplastic resin combined with a cellulose in a 1st process is a pellet shape.   The manufacturing method of the resin composition as described in any one of Claims 1-8 whose ratio of the cellulose in 100 mass% of resin cellulose dispersions obtained in a 1st process is 1-30 mass%.   The manufacturing method of the resin composition as described in any one of Claims 1-9 whose temperature of a 2nd process is 100 degreeC or more and less than 200 degreeC.   The manufacturing method of the resin composition as described in any one of Claims 1-10 which performs at least one part of a 3rd process in the pressure reduction state below atmospheric pressure.   The manufacturing method of the resin composition as described in any one of Claims 1-11 which implements a 1st-3rd process continuously with an extruder.

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