JP2020063347A - Production method of cellulose-blended polyolefin-based resin composition - Google Patents

Abstract

To provide a production method enabling a resin composition having enough physical stability for practical use to be economically dominantly produced without requiring a large number of facilities and long time.SOLUTION: The production method of a resin composition including a polyolefin resin and cellulose is provided in which the cellulose is a cellulose fiber having a diameter of less than 1 μm, a cellulose whisker having a diameter of less than 1 μm or a mixture thereof, and the method includes a first step of preparing a resin cellulose fluid dispersion including a dispersion medium including water as a main component, a polyolefin resin dispersed in the fluid dispersion medium and cellulose, a second step of heating the resin cellulose fluid dispersion while stirring the same, and removing a dispersion medium thereby obtaining a resin cellulose mixture and a third step of melt-kneading the resin cellulose mixture obtained in the second step thereby obtaining a resin composition, the method including the above steps in the order mentioned above, and the second and third steps are carried out using an extruder.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a polyolefin 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, the resin alone often has insufficient mechanical properties, dimensional stability, etc., and composites of resin and various reinforcing materials are generally used.

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

  Therefore, as a technique for dispersing cellulose in a thermoplastic resin up to now, for example, in Patent Document 1, a powdery cellulose is subjected to lipophilic treatment to obtain a mixture uniformly dispersed in a plasticizer and then melt-kneaded with a polyolefin. The technique to do is described. Further, 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 a cellulose dispersion with a resin powder having a specific particle diameter to obtain a cellulose / resin mixture, and then the mixture is melt-kneaded. The technique to do is described. Patent Document 3 describes a technique for obtaining a polyolefin / cellulose nanofiber composition through many treatments such as dehydration drying, dry mixing, solid phase shearing, and melt mixing.

JP, 2016-104874, A International Publication No. 2013/1333093 JP, 2008-297364, A JP, 2017-122177, A

  Generally, in order to add cellulose to the resin, it is necessary to dry and powder the cellulose in advance, but the cellulose becomes a fine aggregate from a finely dispersed state in the process of separating from water, and is difficult to re-disperse. There is a problem such as. This cohesive force is expressed by hydrogen bonds due to the hydroxyl groups of cellulose, and is said to be extremely strong.

  Therefore, in order to exhibit sufficient performance, it is necessary to give strong shearing force to the cellulose to defibrate it to a fiber diameter of 1 μm or less. Further, even if the defibration itself can be sufficiently realized, it is difficult to maintain the defibrated state in the resin, and in the fact that the uniform dispersion of cellulose in the composition is not sufficient. is there.

  If the dispersion homogeneity of the cellulose in the resin composition is not sufficient, the mechanical strength of the molded product will vary depending on the site, and the obtained mechanical properties will be greatly varied. In this case, the molded product partially has a strength defect, and the reliability as an actual product is significantly impaired. Therefore, although cellulose has its excellent properties, it is not practically used in practice.

  Further, although a technique of finely dispersing cellulose by passing through an extremely large number of steps has been proposed, the fact is that productivity is significantly reduced and it cannot be put to practical use.

  The present invention solves the above-mentioned problems and provides a resin composition having sufficient physical property stability that can withstand practical use, a large number of facilities, and a manufacturing method capable of economically advantageous production without requiring a long time. The purpose is to

  The present inventors, in order to solve the above problems, as a result of intensive studies, in producing a cellulose-containing resin composition, cellulose and a polyolefin-based resin, previously dispersed in a dispersion medium containing water as a main component. The inventors have found that the above problems can be solved by forming the above-mentioned mixture, stirring this while heating to remove the dispersion medium, and then melting and kneading the resin, and have completed the present invention.

That is, the present invention includes the following aspects.
[1] A method for producing a resin composition containing a polyolefin resin and cellulose, comprising:
The cellulose is a cellulose fiber having a diameter of less than 1 μm, a cellulose whisker having a diameter of less than 1 μm, or a mixture thereof.
The method is
A dispersion medium containing water as a main component, and a first step of preparing a resin cellulose dispersion liquid containing a polyolefin resin and cellulose dispersed in the dispersion medium,
The second step of heating the resin cellulose dispersion while stirring, removing the dispersion medium to obtain a resin cellulose mixture,
Third step of melt kneading the resin cellulose mixture obtained in the second step to obtain a resin composition,
In this order,
A method for producing a resin composition, wherein the second and third steps are carried out by an extruder.
[2] The method for producing a resin composition according to Aspect 1, wherein the ratio of the polyolefin-based resin in the resin composition is 50 to 99 mass% with respect to 100 mass% of the resin composition.
[3] The aspect 1 or 2 above, wherein the polyolefin-based resin is one or more selected from polyethylene, polypropylene, a copolymer of ethylene and α-olefin, an ethylene-propylene terpolymer, and a mixture thereof. The method for producing the resin composition according to claim 1.
[4] In the first step, the cellulose dispersion prepared by previously dispersing cellulose in a dispersion medium is added to a polyolefin-based resin to obtain the resin cellulose dispersion. A method for producing a resin composition.
[5] The method for producing a resin composition according to any one of the above aspects 1 to 4, wherein more than 50% by mass of the polyolefin resin combined with cellulose in the first step is in a pellet form.
[6] The method for producing a resin composition according to any one of the above aspects 1 to 5, 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.
[7] The method for producing a resin composition according to any one of the above aspects 1 to 6, wherein the temperature in the second step is 100 ° C or higher and lower than 200 ° C.
[8] The method for producing a resin composition according to any one of the above aspects 1 to 7, wherein at least a part of the third step is performed in a reduced pressure state below atmospheric pressure.
[9] The method for producing a resin composition according to any one of the above aspects 1 to 8, wherein the first to third steps are continuously performed by the extruder.
[10] The resin composition according to any one of the above aspects 1 to 9, wherein the extruder is a twin-screw extruder having an L / D obtained by dividing a cylinder length (L) by a screw diameter (D) of 40 or more. Manufacturing method.

  INDUSTRIAL APPLICABILITY The present invention can provide a production method capable of economically producing a polyolefin-based 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 invention are specifically described below, but the 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 polyolefin resin and cellulose. The present manufacturing method includes a first step, a second step and a third step, and the second and third steps thereof are carried out by an extruder.
Hereinafter, they will be described in order.

≪First process≫
This production method requires the first step of preparing a resin cellulose dispersion liquid in which a polyolefin resin and cellulose are dispersed in a dispersion medium containing water as a main component.

(Polyolefin resin)
The polyolefin resin used in the present invention is selected from polyethylene, polypropylene, a copolymer of ethylene and α-olefin (for example, a copolymer of ethylene and propylene), ethylene-propylene terpolymer, and a mixture thereof. However, the present invention is not limited to these.

  The polyolefin resin used in the present invention is a polymer obtained by polymerizing olefins (for example, α-olefins) and alkenes as monomer units. Specific examples include an ethylene-based (co) polymer called polypropylene, such as low-density polyethylene (for example, linear low-density polyethylene), high-density polyethylene, ultra-low-density polyethylene, ultra-high-molecular-weight polyethylene, polypropylene, and the like. Polypropylene (co) polymers such as ethylene-propylene terpolymers exemplified by ethylene-propylene copolymers and ethylene-propylene-diene copolymers, ethylene-acrylic acid copolymers, ethylene-methyl methacrylate copolymers. Examples thereof include copolymers and α-olefin copolymers such as ethylene typified by an ethylene-glycidyl methacrylate copolymer.

  From the viewpoint of cost and recyclability, the most preferable polyolefin resin is a polypropylene (co) polymer. In particular, polypropylene having a melt mass flow rate (MFR) measured at 230 ° C. and a load of 21.2 N in accordance with ISO1133 of 0.5 g / 10 minutes or more and 30 g / 10 minutes or less is preferable. The lower limit of MFR is more preferably 0.7 g / 10 minutes, even more preferably 0.9 g / 10 minutes, and most preferably 1 g / 10 minutes. The upper limit value is more preferably 25 g / 10 minutes, even more preferably 20 g / 10 minutes, and most preferably 18 g / 10 minutes. From the viewpoint of improving the toughness of the composition, the MFR is preferably not more than the above upper limit value, and from the viewpoint of the vacuum formability of the composition, it is preferably not less than the above lower limit value.

  In addition, an acid-modified polyolefin resin can also be suitably used in order to increase the affinity with cellulose. In this case, the acid can be appropriately selected from maleic acid, fumaric acid, succinic acid, phthalic acid and their anhydrides, and polycarboxylic acids such as citric acid. Among these, maleic acid or its anhydride is preferable because of its high modification rate. The modification method is not particularly limited, but it is generally a method of melting and kneading by heating above the melting point in the presence / absence of a peroxide. As the acid-modified polyolefin resin, all of the above-mentioned polyolefin resins can be used, but polypropylene can be preferably used. Although the acid-modified polypropylene may be used alone, it is more preferably used as a mixture with unmodified polypropylene in order to adjust the modification rate as a composition. The ratio of the acid-modified polypropylene to all polypropylenes at this time is 0.5% by mass to 50% by mass. A more preferred lower limit is 1% by mass, further preferably 2% by mass, even more preferably 3% by mass, particularly preferably 4% by mass, and most preferably 5% by mass. The more preferable upper limit is 45% by mass, further preferably 40% by mass, even more preferably 35% by mass, particularly preferably 30% by mass, and most preferably 20% by mass. In order to maintain the interfacial strength with the cellulose, the lower limit or more is preferable, and in order to maintain the ductility as a resin, the upper limit or less is preferable.

  A preferred melt mass flow rate (MFR) of acid-modified polypropylene measured at 230 ° C. under a load of 21.2 N in accordance with ISO1133 is 10 g / 10 minutes or more in order to enhance affinity with a cellulose interface. It is preferable. A more preferred lower limit is 20 g / 10 minutes, even more preferred is 30 g / 10 minutes, and most preferred is 50 g / 10 minutes. The upper limit is not particularly limited, but a preferable upper limit is 200 g / 10 minutes from the viewpoint of maintaining mechanical strength. By setting the MFR within this range, the advantage that acid-modified polypropylene is likely to exist at the interface between the cellulose and the resin can be enjoyed.

  In one aspect, the melting point of the polyolefin resin is preferably 50 ° C to 200 ° C. A preferable example of the lower limit of the melting point is 80 ° C., or 90 ° C., or 100 ° C., or 110 ° C. from the viewpoint of suppressing deformation by heat, and a preferable example of the upper limit of the melting point is 190 ° C. from the viewpoint of suppressing discoloration. Or 180 ° C. or 170 ° C.

  In the present invention, it is desirable that the ratio of the polyolefin resin in pellet form (pellet ratio) is more than 50% by mass in 100% by mass of the polyolefin 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 (that is, substantially all are in the form of pellets). . In the second step, in order to suppress the aggregation of cellulose when heating the resin cellulose dispersion while stirring 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 it is preferable that the cellulose be fine cellulose in order to finely disperse it in the resin composition. More specifically, it is desirable that the nanometer size, that is, the diameter is less than 1 μm. Further, the type of cellulose is more preferably cellulose fiber, cellulose whisker or a mixture thereof.

  In the present disclosure, the “length” (L) and “diameter” (D) of cellulose correspond to the long diameter and the short diameter in cellulose whiskers, and the fiber length and the fiber diameter in the cellulose fiber, respectively. As the cellulose whiskers and the cellulose fibers, those each having a diameter of nanometer size (that is, less than 1 μm) are preferable from the viewpoint of maintaining a good coefficient of variation in tensile breaking strength. Each of the cellulose whiskers and the cellulose fibers that can be preferably used in the present invention has a diameter of 500 nm or less. The preferable upper limit of the diameter of cellulose is 450 nm, more preferably 400 nm, even more preferably 350 nm, and most preferably 300 nm.

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

  Moreover, in a particularly preferred embodiment, the diameter of the cellulose fiber is preferably 1 nm or more, more preferably 5 nm or more, even more preferably 10 nm or more, particularly preferably 15 nm or more, and most preferably 20 nm or more. And 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 keep the coefficient of variation in tensile breaking strength of the resin composition good, it is desirable that the diameter of the cellulose be within the above range.

  The cellulose whisker in the present invention refers to crystalline cellulose that remains after the pulp or the like is used as a raw material and the amorphous portion of the cellulose is dissolved in an acid such as hydrochloric acid or sulfuric acid.

  Cellulose fibers are processed by treating pulp or the like with hot water at 100 ° C. or higher to hydrolyze and weaken the hemicellulose portion, and then defibrated by a pulverizing method such as a high pressure homogenizer, a microfluidizer, a ball mill or a disc mill. Cellulose and cellulose fibers defibrated by TEMPO oxidation method, not by strong mechanical defibration such as crushing, chemical modification of cellulose fiber hydroxyl group in organic solvent, and modification of hydroxyl group by chemical modification after defibration Also included are modified cellulose fibers.

  The preferred length / diameter ratio (L / D ratio) of the cellulose whiskers is less than 30. The upper limit of L / D of the cellulose whiskers is preferably 25, more preferably 20, more preferably 15, still more preferably 10, and most preferably 5. The lower limit is not particularly limited, but may be greater than 1. In order to impart appropriate fluidity to the resin composition, the L / D ratio of the cellulose whiskers is preferably within the above range.

  The lower limit of L / D of the cellulose fiber is preferably 30, more preferably 50, more preferably 80, even more preferably 100, particularly preferably 120, and most preferably 150. . The upper limit is not particularly limited, but is preferably 1000 or less from the viewpoint of not making the melt viscosity of the resin composition too high.

  In the present disclosure, the length, diameter, and L / D ratio of each of the cellulose whiskers and the cellulose fibers are obtained by using a high shear homogenizer (for example, manufactured by Nippon Seiki Co., Ltd.) Name "Excel Auto Homogenizer ED-7"), treatment conditions: an aqueous dispersion dispersed at a rotation speed of 15,000 rpm for 5 minutes was diluted with pure water to 0.1 to 0.5% by mass, and mica was added. The sample cast on the air and dried in air is used as a measurement sample and measured by a high resolution scanning microscope (SEM) or an atomic force microscope (AFM). Specifically, the length (L) and diameter (D) of 100 randomly selected celluloses and the ratio (in the observation visual field in which the magnification was adjusted so that at least 100 celluloses were observed, It can be confirmed by calculating L / D). The length and diameter of the cellulose of the present disclosure are the number average values of 100 celluloses in total. For each of the cellulose whiskers and the 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. Further, in the present disclosure, cellulose whiskers and cellulose fibers can be distinguished from each other by classifying those having a ratio (L / D) of less than 30 as cellulose whiskers and those having a ratio of 30 or more as cellulose fibers.

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

  Alternatively, the length, diameter, and L / D ratio of each of the cellulose whiskers and the cellulose fibers in the composition are such that the resin component in the composition is dissolved in an organic or inorganic solvent capable of dissolving 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, and diluted with pure water so that the cellulose concentration is 0.1 to 0.5% by mass, It can be confirmed by measuring the sample cast on mica and air-dried as a measurement sample by the above-mentioned measurement method. At this time, the cellulose to be measured is 100 or more randomly selected L / D cellulose fibers having a L / D of 30 or more and 100 or more cellulose whiskers having an L / D of less than 30 and a total of 200 or more.

  The cellulose whisker that can be preferably 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 whiskers themselves are enhanced, and therefore when dispersed in a resin, the strength and dimensional stability of the resin composition tend to be high.

  The crystallinity of the cellulose whiskers is preferably 60% or more, more preferably the lower limit of the crystallinity is 65%, even more preferably 70%, and most preferably 80%. Since the higher the crystallinity of the cellulose whiskers tends to be, the upper limit is not particularly limited, but 99% is the 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 in this range, the mechanical properties (strength and dimensional stability) of the cellulose fiber itself are enhanced, and therefore when dispersed in a resin, the strength and dimensional stability of the resin composition tend to be high. The lower limit of the crystallinity is more preferably 60%, even 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 from the viewpoint of production, the upper limit is preferably 99%.

  The crystallinity of cellulose whiskers and cellulose fibers depends on the degree of removal of the amorphous portion during the production of these celluloses, but under the production conditions that increase the degree of removal of the amorphous portion, the removal of impurities such as lignin The degree becomes higher. When the residual amount of impurities such as lignin is large, it may cause discoloration due to heat during processing of the resin composition, so from the viewpoint of suppressing discoloration of the resin composition during extrusion and molding, cellulose whiskers and It is desirable that the crystallinity of the cellulose fiber be within the above range.

The crystallinity referred to here is 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). It is calculated by the following formula by the method.
Crystallinity (%) = ([2θ / deg. = Diffraction intensity due to (200) plane of 22.5) − [2θ / deg. = Diffraction intensity due to amorphous of 18]) / [2θ / Deg. = Diffraction intensity due to (200) plane of 22.5] × 100
When the cellulose is cellulose II type crystals (derived from regenerated cellulose), the crystallinity is 2θ = 12.6 °, which is assigned to the (110) plane peak of the cellulose II type crystals in wide-angle X-ray diffraction. It is calculated from the absolute peak intensity h0 and the peak intensity h1 from the baseline at this plane interval by the following formula.
Crystallinity (%) = h1 / h0 × 100

  As crystal forms of cellulose, I-type, II-type, III-type, IV-type, etc. are known. While I-type and II-type celluloses are widely used, III-type and IV-type celluloses are in laboratory scale. However, it is not widely used on an industrial scale. As the cellulose used in the present invention, a resin composite having a relatively high structural flexibility, a lower linear expansion coefficient by dispersing the cellulose in a resin, a tensile strength, and a more excellent strength and elongation during bending deformation. From the fact that it can be obtained, cellulose containing cellulose type I crystal or cellulose type II crystal is preferable, and cellulose containing type I crystal and having a crystallinity of 55% or more is more preferable.

  The degree of polymerization of the cellulose whiskers 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 viewpoints of processability in extrusion molding and expression of mechanical properties of the molded product, it is preferable that the degree of polymerization of the cellulose whiskers and cellulose fibers is not too high, and from the viewpoint of expression of mechanical properties, it is desirable that the polymerization degrees are not too low.

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

  Examples of the method for controlling the degree of polymerization of cellulose (that is, the average degree of polymerization) include hydrolysis treatment. By the hydrolysis treatment, depolymerization of the amorphous cellulose inside the cellulose fiber progresses, and the average degree of polymerization becomes small. 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 inside of the fiber becomes porous. This makes it easier for the cellulose component to undergo mechanical treatment in the process of applying mechanical shearing such as the extrusion process described later, and the cellulose component is likely to be micronized.

  The method of hydrolysis 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 in which this is dispersed in an aqueous medium, a suitable amount of a protonic acid, a carboxylic acid, a Lewis acid, a heteropolyacid, or the like. 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 differ depending on the type of cellulose, the concentration of cellulose, the type of acid and the concentration of acid, but are appropriately adjusted so that the desired average degree of polymerization is achieved. For example, there may be mentioned a condition in which a 2% by mass or less aqueous mineral acid solution is used and the cellulose is treated under pressure at 100 ° C. or higher for 10 minutes or longer. Under these conditions, a catalyst component such as an acid penetrates into the inside of the cellulose fiber, the hydrolysis is promoted, the amount of the catalyst component used becomes small, and the subsequent purification becomes easy. 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 addition to water as long as the effect of the present invention is not impaired.

  The cellulose whiskers and cellulose fibers in the embodiment of the present invention also include modified products obtained by modifying the hydroxyl groups that cellulose has in the basic skeleton by chemical modification. Examples of the preferred method for adding a modifying group to cellulose include esterification, acid anhydride, etherification, silylation, cationization, phosphorylation, carboxyalkylation, and sulfation. Among these, esterification, acid Anhydride conversion and etherification are more preferable. Among these, esterification is the most preferable from the viewpoints of having a low environmental load during production and being economically excellent, and among the esterifications, acetylation is most preferable.

(Dispersion medium)
The dispersion medium in the cellulose dispersion liquid in the present invention is a dispersion medium containing water as a main component. The term "mainly composed of water" as used herein means that the proportion of water in the dispersion medium is 50% by mass or more. Examples of the dispersion medium other than water include an organic solvent compatible with water, an organic solvent incompatible with water, a surfactant, and the like.

  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.

  The water-insoluble organic solvent refers to an organic solvent that has a solubility in water of 1% by mass or less and is hardly soluble. Specific examples thereof include, but are not limited to, ethyl acetate, dichloromethane, chloroform, carbon tetrachloride, toluene, xylene, cyclohexane, pentane, heptane, and the like.

  Further, as the surfactant, any of anionic surfactants, nonionic surfactants, zwitterionic surfactants and cationic surfactants can be used, but they have an affinity with cellulose. In this respect, anionic surfactants and nonionic surfactants are preferable, and nonionic surfactants are more preferable.

  Examples of the anionic surfactant include fatty acid-based (anion) fatty acid sodium, fatty acid potassium, sodium alphasulfofatty acid ester sodium, and the like, and linear alkylbenzene-based agent includes linear alkylbenzene sulfonate sodium and the like. Examples of the alcohol type (anion) include sodium alkyl sulfate ester, sodium alkyl ether sulfate, and the like, such as alpha olefin type sodium alpha olefin sulfonate and the like, normal paraffin type sodium alkyl sulfonate, and the like. 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 ester, sorbitan fatty acid ester, and polyoxyethylene sorbitan fatty acid ester, and fatty acid alkanolamide. Examples of the ion) include polyoxyethylene alkyl ether and the like, and examples of the alkylphenol type include polyoxyethylene alkylphenyl ether and the like, and it is possible to use one kind or a mixture of two or more kinds thereof.

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

  Examples of the cationic surfactant include alkyl trimethyl ammonium salt and dialkyl dimethyl ammonium salt as the quaternary ammonium salt type, and it is possible to use one kind or a mixture of two or more kinds thereof. .

  Surfactants may be derivatives of fats and oils. Examples of fats and oils include esters of fatty acids and glycerin, and usually those in the form of triglyceride (tri-O-acylglycerin). Dry oils, semi-dry oils, non-dry oils are classified in order from fatty oils that are easily oxidized and solidified, and those used in various applications such as food and industry can be used. They can be used alone or in combination of two or more.

  Examples of fats and oils include animal and vegetable oils such as terpine oil, tall oil, rosin, white squeezing oil, corn oil, soybean oil, sesame oil, rapeseed oil (canola oil), rice oil, bran oil, camellia oil, safflower oil (safflower oil). , Coconut oil (palm kernel oil), cottonseed oil, sunflower oil, perilla oil (sesame 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 fat), het (beef fat), chicken oil, rabbit fat, sheep fat, horse fat, schmalz, milk fat (butter, butter, Gee, etc.), hydrogenated oil (margarine, shortening, etc.), castor oil (vegetable oil) and the like.

  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.

(Preparation of resin cellulose dispersion)
In the first step, the resin cellulose dispersion is prepared by previously preparing a cellulose dispersion prepared by dispersing cellulose in a dispersion medium containing water as a main component, and adding the cellulose dispersion to a polyolefin resin. It is preferable to prepare. 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 the cellulose in the dispersion medium can be easily grasped and controlled, and as a result, the diameter of the cellulose in the resin cellulose dispersion can be stabilized.

  A cellulose dispersion liquid in which cellulose is dispersed in a dispersion medium containing water as a main component can be obtained by various methods. To give a specific example, pulp, which is a raw material, is treated with hot water at 100 ° C. or higher to hydrolyze and weaken the hemicellulose portion, and then pulverized by a high pressure homogenizer, a microfluidizer, a ball mill or a disc mill. Method of defibrating, cutting pulp as raw material, dissolving amorphous portion of cellulose in acid such as hydrochloric acid or sulfuric acid, then neutralizing, crushing raw pulp, hot water at 100 ° C or higher, etc. A method in which the pulp obtained by treating with water, dehydration, and the like is stirred with a stirrer, defibrated 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, after obtaining as powdery cellulose, blended to have a desired cellulose concentration, a high-pressure homogenizer together with a dispersion medium, a microfluidizer, A method of applying shear under conditions of an apparatus such as a ball mill or a disk mill for applying shear and redispersion can also be suitably used.

  Next, a resin cellulose dispersion can be obtained by adding the cellulose dispersion to the polyolefin resin. As a method of addition, the polyolefin resin is supplied to the extruder in the form of pellets, powder or the like (preferably a pellet ratio of more than 50% by mass), and then the cellulose dispersion is added to the polyolefin resin under shearing conditions. A method of kneading and kneading to obtain a resin cellulose dispersion can be exemplified.

  The preferred 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 polyolefin resin. The lower limit of the amount of cellulose based on 100 parts by mass of the polyolefin resin is more preferably 2 parts by mass, even 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, even more preferably 50 parts by mass, particularly preferably 45 parts by mass, and most preferably 30 parts by mass. In order to enhance the dispersibility of cellulose in the obtained resin composition and enhance the physical stability of the molded product, the above range is desired. Further, the lower limit amount of the dispersion medium is more preferably 5 parts by mass, even more preferably 10 parts by mass, even 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, further preferably 120 parts by mass, even more preferably 110 parts by mass, and most preferably 100 parts by mass.

  The proportion of cellulose in 100% by mass of the resin cellulose dispersion obtained in the first step is preferably 1 to 30% by mass. The lower limit of the above ratio is more preferably 2% by mass, even more preferably 3% by mass, and particularly preferably 5% by mass. The upper limit of the above ratio is more preferably 25% by mass, even more preferably 20% by mass, and particularly preferably 15% by mass. In order to enhance the dispersibility of cellulose in the obtained resin composition and enhance the physical property stability of the molded product, the above range is desired.

<< Second step >>
This production method requires a second step, which is carried out following the first step, to heat the resin cellulose dispersion while stirring to remove the dispersion medium to obtain a resin cellulose mixture.

  It is known that cellulose is stably finely dispersed in a dispersion liquid. In the second step, by heating the resin cellulose dispersion while stirring to remove the dispersion medium, it is possible to remove the dispersion medium by heating the cellulose while rubbing it with the resin to remove the dispersion medium. Agglomeration of cellulose due to removal can be significantly suppressed, and the dispersibility of cellulose in the obtained resin composition can be enhanced. Therefore, the second step is very important.

  As described above, the second step has a role of removing the dispersion medium containing water as the main component while applying shear to the resin cellulose dispersion. Since the dispersion medium contains water as a main component, the heating temperature in the second step is preferably 100 ° C. or higher and lower than 200 ° C. The upper limit is more preferably 180 ° C, still more preferably 170 ° C, even more preferably 160 ° C, most preferably 150 ° C. The lower limit is more preferably 105 ° C, even more preferably 110 ° C, most preferably 115 ° C. Further, the upper limit temperature is preferably equal to or lower than the melting point of the polyolefin-based resin to be used (in the case of two or more kinds of polyolefin-based resins, the resin having the largest content of the two or more kinds). In addition, the heating temperature in the second step is gradually increased within the above temperature range (that is, a temperature gradient over time is provided), for example, 100 ° C-120 ° C-150 ° C-160 ° C. Are preferable from the viewpoint of suppressing aggregation of cellulose.

≪Third process≫
In the present invention, it is necessary to provide a third step of melt-kneading the cellulose resin mixture obtained in the second step, following the second step.

  The temperature of the third step is set depending on the types of the polyolefin resin and cellulose, but it is higher than or equal to the temperature at which the polyolefin resin can be melt-kneaded, and lower than the thermal decomposition start temperature of the polyolefin resin and cellulose. desirable. In one aspect, the lower limit of the temperature in the third step is preferably at least 10 ° C. higher than the melting point of the polyolefin resin.

  Further, in the third step, it is more preferable to remove a volatile component and water vapor from the resin kneaded material by making a part of the step a reduced pressure state below atmospheric pressure.

  In the present invention, it is important to carry out the second and third steps with an extruder. By using the extruder, the resin composition can be produced in a short time without using any equipment other than the extruder, and the production which is very economically advantageous can be performed. More preferably, the mixing of the resin and the cellulose dispersion in the first step, the second step and the third step are all performed by an extruder. Even more preferably, the first step (particularly the step of mixing the resin and the cellulose dispersion liquid), the second step and the third step are continuously carried out by an extruder.

  Extruders that can be used in the present invention include single-screw extruders, twin-screw extruders, and multi-screw extruders. Among these, a twin-screw extruder can be preferably used. Further, among the twin-screw extruders, a twin-screw extruder having a long stroke of L / D obtained by dividing the cylinder length (L) by the screw diameter (D) of 40 or more can be more preferably used. Further, an extruder having a structure in which a plurality of vent ports capable of removing the dispersion medium can be installed above the extruder can be most preferably used. A more preferable extruder has an L / D of 45 or more, more preferably 48 or more, and most preferably 50 or more. The upper limit is 100 due to the limitation of the motor capacity. In addition, by mixing the cellulose dispersion in the first step with the polyolefin resin in the extruder, the cellulose is subjected to a strong shear of friction with the resin (preferably pellets) and the dispersion medium is almost instantaneously added. Since it becomes possible to remove the water in it, it becomes possible to express a high degree of cellulose dispersibility to the extent that the physical stability of the obtained molded product is enhanced, and furthermore, all the steps are performed in a single extruder. Since it can be carried out in a process, it can be economically superior.

  A preferable ratio of the polyolefin 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, even more preferably 60% by mass, even 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, most preferably 97% by mass, and the particularly preferable upper limit is 95% by mass.

  The preferable ratio of cellulose in the resin composition obtained by the production method of the present invention is 1 to 60% by mass. The lower limit amount is more preferably 2% by mass, further preferably 3% by mass, particularly preferably 5% by mass. The upper limit amount is more preferably 50% by mass, further preferably 40% by mass, even more preferably 30% by mass, particularly preferably 20% by mass, and most preferably 10% by mass.

  Further, in the present invention, in addition to the above-mentioned components, additional components may be added as necessary within a range not impairing the effects of the present invention. The addition amount of these additional components is preferably within the range of not more than 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, zonotolite, wollastonite, potassium titanate, glass fibers, etc.), known fillers 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 phosphoric acid ester compounds, ammonium polyphosphate, red phosphorus, etc.), fluorinated polymers that exhibit anti-dripping effects, Plasticizers (oil, low molecular weight polyolefin, polyethylene glycol, fatty acid esters, etc.), flame retardant aids such as antimony trioxide, coloring agents such as carbon black for coloring, antistatic agents, various peroxides, antioxidants, Examples thereof include ultraviolet absorbers and light stabilizers.

  INDUSTRIAL APPLICABILITY According to the production method of the present invention, it is possible to highly disperse cellulose in a polyolefin-based resin, and the stability of the physical properties is excellent, so that the production method can be used for large-sized molded articles and the like. Further, since the extensional viscosity of the obtained resin composition can be improved, it can be used for a material or the like which is stretched in a molten state. Specifically, it is formed by injection molding, sheet molding, blow molding, vacuum molding, inflation molding, etc., and is required to have reliability, such as automobile exterior materials, structural members such as chassis, interior members, drive members such as gears, etc. 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]
The raw materials used and the evaluation method will be described below.
≪Polyolefin resin≫
Polypropylene (hereinafter referred to as unit PP)
Novatec PP (Japan Polypro Corporation) EA7AD (MFR = 1.4g / 10min)
Low density polyethylene (hereinafter simply referred to as LDPE)
Suntech LD (Asahi Kasei Corporation) B161 (MFR = 1.4g / 10min)
Ethylene-butene copolymer (hereinafter simply referred to as PEB)
Creolex (Asahi Kasei Corporation) K4125 (MFR = 2.5g / 10min)
Maleic anhydride modified polypropylene (hereinafter simply referred to as MPP)
2 parts by weight of maleic anhydride and 0.05 parts by weight of Perhexa 25B were mixed with 100 parts by weight of MA3 (MFR = 11 g / 10 minutes) manufactured by Novatec PP (Japan Polypro Co., Ltd.), and twin screw extrusion set to 200 ° C. Melt kneading was carried out by a machine, and free maleic anhydride was removed by suction under reduced pressure, and the mixture was extruded in a strand shape, cooled with water, and cut to obtain maleic anhydride-modified polypropylene pellets. The MFR of the obtained MPP was 25 g / 10 minutes. Further, the maleic anhydride addition rate was 0.89 mass% as determined by the previously prepared calibration curve as the absorbance ratio of the characteristic absorption band of the infrared absorption spectrum.

≪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 Hirokawa Shoten).
<Cellulose crystal form and crystallinity>
An X-ray diffractometer (manufactured by Rigaku Corporation, multipurpose X-ray diffractometer) was used to measure a diffraction pattern (at room temperature) by the powder method, and the crystallinity was calculated by the 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", processing condition: rotation speed 15,000 rpm x 5 minutes) was used. 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 the minor axis (D) of the particle image were measured, the ratio (L / D) was calculated from these values, and the average value of 100 to 150 particles was calculated.

<Average diameter of cellulose>
Kneading with cellulose at a solid content of 40% by mass in a planetary mixer (manufactured by Shinagawa Kogyo Co., Ltd., trade name "5DM-03-R", with stirring blades of hook type) at 126 rpm at room temperature and atmospheric pressure for 30 minutes. did. Then, a pure water suspension was prepared with a 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", processing condition: rotation speed 15,000 rpm x 5 minutes) to disperse and centrifuge (manufactured by Kubota Shoji Co., Ltd., trade name "6800 type centrifuge", rotor type RA-400 type, processing conditions: centrifugal force 39,200 m ² / s for 10 minutes The collected supernatant was centrifuged at 116000 m ² / s for 45 minutes). Volume obtained by laser diffraction / scattering particle size distribution analyzer (manufactured by Horiba, Ltd., trade name “LA-910”, ultrasonic treatment 1 minute, refractive index 1.20) using the supernatant after centrifugation. The cumulative 50% particle size (volume average particle size) in the frequency particle size distribution was measured, and this value was taken as the average size.

<Cellulose dispersibility>
After the resin composition pellets were injection molded into the shape of an ISO multipurpose test piece, the central part of the molded piece was measured with a high resolution 3DX ray microscope (nano3DX: manufactured by Rigaku Corporation), an X-ray tube voltage of 40 kV, and a tube. CT measurement was carried out 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 it is present in the composition as an aggregate having a spatial resolution or higher, 5% by volume will be calculated as a foreign substance.

<Variation coefficient of tensile breaking strength>
Using a multipurpose test piece compliant with ISO294-3, tensile rupture strength was measured at n number 15 according to ISO527, and the coefficient of variation (CV) was calculated based on the following equation based on the obtained data. did.
CV = (σ / μ) × 100
Here, σ is the standard deviation, and μ is the arithmetic mean of tensile strength at break.

<Nominal tensile strain>
The nominal strains for tensile fracture at the time of measuring the coefficient of variation of tensile fracture strength were measured, respectively, and averaged.

<Fender defect rate>
Using a resin composition pellet, the cylinder temperature of an injection molding machine with a maximum mold clamping pressure of 4000 tons was set to 250 ° C., and a predetermined mold (cavity) capable of molding a fender having the shape shown in the schematic view of FIG. Volume: about 1400 cm3, average thickness: 2 mm, projected area: about 7000 cm2, number of gates: 5 points, hot runner: In addition, in FIG. 1, runners (hot runners) are used to clarify the runner position of the molded body. Relative position 1 was shown), 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 to the center of the fender to confirm the state of destruction of the fender. The number of destroyed pieces was counted out of 20 pieces.

<< Extruder configuration >>
<Structure in Example>
A liquid injection nozzle is installed in the cylinder 3 of a twin-screw extruder having 13 cylinder blocks (STEER OMEGA30H, L / D = 60), the cylinder 1 is water-cooled, the cylinders 2 to 4 are 80 ° C., and the cylinder 5 is The temperature was set to 100 ° C, the temperature of the cylinder 6 was 130 ° C, the temperature of the cylinder 7 was 200 ° C, and the temperature of the cylinders 8 to 13 and the die were 220 ° C.

  As for the screw configuration, cylinders 1 to 4 are used as a transport zone composed only of transport screws, and three clockwise kneading discs (feed type kneading discs: hereinafter referred to simply as RKD) are provided in each of cylinders 5 and 6 from the upstream side. ), And a vent port was installed above the extruder so that the dispersion medium could be removed. Subsequently, three RKDs, two neutral kneading discs (no-conveying type kneading discs: hereinafter sometimes simply referred to as NKD), and one counterclockwise kneading disc from the cylinders 7 to 8. (Reverse feed type kneading disc: hereinafter sometimes simply referred to as LKD) was continuously arranged to form a melting zone. The cylinder 9 was used as a transfer zone, and one RKD, two NKD and one LKD were continuously arranged in this order in the cylinder 10 to form a melting zone, and then the cylinders 11 to 13 were used as transfer zones. Here, the cylinder 12 enables vacuum suction.

  The individual steps of the present invention in this extruder configuration are described below to aid understanding.

  For example, when the polyolefin resin is supplied from the cylinder 1 and the cellulose dispersion is added from the cylinder 3, the cylinders 3 and 4 after adding the dispersion are the first step in the present invention. Further, the cylinders 5 and 6 remove the dispersion medium while stirring, which is the second step of the present invention. Further, the cylinder 8 and thereafter are zones for melt-kneading the resin cellulose mixture, which is the third step in the present invention.

<Structure in Comparative Example>
With the configuration of the example, except that the cylinder 1 of the twin-screw extruder was water-cooled, the cylinders 2 to 4 were set to 200 ° C, the cylinders 5 to 13 and the die were set to 220 ° C, and the liquid injection nozzle was not installed in the cylinder 3. It carried out similarly.

[Preparation Example 1] Preparation of Cellulose Fiber Dispersion After cutting linter pulp, it was heated in an autoclave in hot water at 120 ° C or higher for 3 hours to squeeze the purified pulp from which the hemicellulose portion was removed, in pure water. After beating to a high degree of short fibers and fibrils by beating to a solids content of 1.5% by weight, defibration is performed with a high-pressure homogenizer (operating pressure: 85 MPa, 10 times treatment) at the same concentration. Thus, defibrated cellulose was obtained. Here, in the beating process, a disc refiner is used, and a beating blade having a high cutting function (hereinafter referred to as a cutting blade) is used for 4 hours, and then a beating blade having a high defibration function (hereinafter referred to as a defibrating blade) is used. Further, beating was carried out for 1.5 hours to obtain cellulose fibers. The characteristics of the obtained cellulose fiber were evaluated by the above-mentioned methods. 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 centrifugally filtered 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 degree of polymerization 1600) was cut and hydrolyzed in a 10% aqueous hydrochloric acid solution at 105 ° C. for 30 minutes. The resulting acid-insoluble residue was filtered, washed, and pH-adjusted to prepare a cellulose whisker dispersion liquid having a solid content concentration of 14% by weight and a pH of 6.5. The characteristics of the obtained cellulose whiskers were evaluated by the methods described above. The results are shown below.
L / D = 1.6
Average diameter = 200 nm
Crystallinity = 78%
Degree of polymerization = 200

[Preparation Example 3] Preparation of Cellulose Fiber Surfactant Dispersion Liquid In the cellulose fiber dispersion liquid prepared in Preparation Example 1, a polyoxyethylene-cured castor oil ether as a surfactant (a brown oil manufactured by Aoki Yushi Kogyo Co., Ltd.) as a dispersion medium other than water RCW-20) was added in an amount of 20 parts by mass with respect to 100 parts by mass of the total amount of cellulose, and the mixture was stirred to prepare a cellulose fiber surfactant dispersion liquid.

[Preparation Example 4]
The cellulose fiber dispersion obtained in Preparation Example 1 and the cellulose whiskers obtained in Preparation Example 2 were mixed with a stirrer so that the mass ratio of the cellulose fibers and the cellulose whiskers in the dispersion was 2: 8. To the obtained cellulose mixed dispersion, a polyoxyethylene hydrogenated castor oil ether, which is a surfactant, is added as a dispersion medium other than water in an amount of 20 parts by mass with respect to 100 parts by mass of the total amount of cellulose, and the mixture is stirred to form a cellulose interface. An activator mixed dispersion was prepared.

[Preparation Example 5] Preparation of PP powder The PP pellets were freeze-pulverized using a Linrex mill while cooling with liquid nitrogen to obtain PP powders having an average particle diameter of about 350 µm.

[Example 1]
<Step 1> Step of Preparing Resin Cellulose Dispersion A PP powder is prepared so that the PP powder obtained in Preparation Example 5 and the cellulose fiber dispersion obtained in Preparation Example 1 have the compositions shown in Table 1. From the cylinder 1 of the extruder, the cellulose fiber dispersion obtained in Preparation Example 1 was added from the cylinder 3, and both were mixed in the portions of cylinders 3 and 4 in the extruder to prepare a resin cellulose dispersion. At this time, the rotation speed of the extruder was set to 300 rpm in order to enhance 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, corresponds 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 above the extruder.
<Step 3> Step of Melt-Kneading Resin Cellulose Mixture The resin cellulose mixture obtained in Step 2 was melt-kneaded in the cylinder 7 or later corresponding to Step 3 to obtain resin composition pellets. At this time, the pressure was not reduced in this step.

[Example 2]
All were performed in the same manner as in Example 1 except that the cellulose dispersion liquid added from the cylinder 3 in Step 1 was changed to the cellulose whisker fiber dispersion liquid obtained in Preparation Example 2 so that the composition shown in Table 1 was obtained. .

[Example 3]
In the same manner as in Example 1 except that the cellulose dispersion added from the cylinder 3 in Step 1 was changed to the cellulose surfactant mixed dispersion obtained in Preparation Example 4 so that the composition shown in Table 1 was obtained. Carried out.

[Example 4]
In step 1, except that the PP added from the cylinder 1 was changed to PP powder and MPP, the same procedure as in Example 3 was performed.

[Example 5]
In step 1, except that the PP added from the cylinder 1 was changed to a mixture of PP powder, PP pellets and MPP, the same procedure as in Example 3 was performed.

[Example 6]
In step 1, except that the PP added from the cylinder 1 was changed to PP pellets and MPP, the same procedure as in Example 3 was performed.

[Example 7]
In step 3, the same procedure as in Example 6 was performed except that the pressure of the cylinder 12 was reduced.

[Example 8]
All except that the resin added from the cylinder 1 was PP powder and the cellulose dispersion added from the cylinder 3 was the cellulose fiber surfactant dispersion obtained in Preparation Example 3 so as to have the composition shown in Table 1. It carried out like Example 7.

[Example 9]
The same procedure as in Example 7 was performed except that PP, MPP, and LDPE were supplied from the cylinder 1.

[Example 10]
The same procedure as in Example 7 was performed except that PP, MPP and PEB were supplied from the cylinder 1.

[Comparative Example 1]
<Step of preparing resin cellulose dispersion>
To 100 parts by mass of the PP powder obtained in Preparation Example 5, 110 parts by mass of the cellulose fiber dispersion obtained in Preparation Example 1 was added and mixed with a stirrer to prepare a resin cellulose dispersion.
<Step of heating dispersion liquid while stirring to remove dispersion medium to obtain resin cellulose mixture>
The resin cellulose dispersion obtained in the above step is placed in a closed planetary mixer (manufactured by Kodaira Seisakusho, trade name "ACM-5LVT", stirring blade is hook type) at 70 rpm for 80 minutes at 25 ° C and atmospheric pressure. After stirring treatment with, a 60 ° C. hot bath was set under a reduced pressure condition of −0.1 MPa, and a reduced pressure drying treatment was performed at 307 rpm for 5 hours to obtain a resin cellulose mixture.
<Step of melt-kneading resin cellulose mixture>
The resin cellulose mixture obtained in the above step was supplied from the cylinder 1 of the extruder and melt-kneaded to obtain resin composition pellets. At this time, the screw rotation speed was set to 300 rpm as in the example, and the cylinder 12 was depressurized.

[Comparative Example 2]
<Step of preparing resin cellulose dispersion>
To 100 parts by mass of the PP powder obtained in Preparation Example 5, the cellulose surfactant mixed dispersion obtained in Preparation Example 4 was added and mixed with a stirrer to prepare a resin cellulose dispersion.
<Step of heating dispersion liquid while stirring to remove dispersion medium to obtain cellulose resin mixture>
The procedure of Comparative Example 1 was repeated except that the resin cellulose dispersion obtained in the above step was used.
<Step of melt-kneading resin cellulose mixture>
The procedure of Comparative Example 1 was repeated except that the resin cellulose mixture obtained in the above step was used.

[Comparative Example 3]
<Step of preparing resin cellulose dispersion>
To 100 parts by mass of the PP powder obtained in Preparation Example 5, 105 parts by mass of the cellulose fiber dispersion prepared in Preparation Example 1 was mixed, and this was subjected to centrifugal filtration, and the total amount of the resin and the cellulose fiber was 60 parts by mass. % Resin cellulose dispersion was prepared.
<Step of heating dispersion liquid without stirring to remove dispersion medium to obtain resin cellulose mixture>
The resin cellulose dispersion obtained in the above step was dried using a vacuum dryer set at 80 ° C. to obtain a dried resin cellulose fiber. Since the dried product had a lump state, it was pulverized for 5 minutes in a Henschel mixer having a volume of 10 liters to obtain a powdery resin cellulose fiber mixture.
<Step of melt-kneading resin cellulose mixture>
The resin cellulose fiber mixture obtained in the above step was supplied from the cylinder 1 of the extruder in an amount of 15 kg / h, and melt-kneaded.

[Comparative Example 4]
<Step of heating dispersion liquid while stirring to remove dispersion medium to obtain cellulose fiber powder>
The cellulose fiber dispersion obtained in Preparation Example 1 was stirred in a closed planetary mixer at 70 rpm for 80 minutes at 25 ° C. and atmospheric pressure in the same manner as in Comparative Example 1, and then a reduced pressure condition of −0.1 MPa was applied. Then, a 60 ° C. hot bath was set and dried under reduced pressure at 307 rpm for 5 hours to obtain a cellulose fiber powder.
<Process of melt-kneading cellulose fiber powder and PP powder>
The PP powder obtained in Preparation Example 5 and the cellulose fiber powder obtained in the above step were dry-blended so as to have the ratio shown in Table 2, and supplied from the cylinder 1 of the extruder in an amount of 15 kg / h. , Melt kneading was carried out.

[Comparative Example 5]
The same procedure as in Comparative Example 2 was carried out except that the resin used was PP (pellet).

  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, and precision parts.

Claims (10)

A method for producing a resin composition containing a polyolefin resin and cellulose,
The cellulose is a cellulose fiber having a diameter of less than 1 μm, a cellulose whisker having a diameter of less than 1 μm, or a mixture thereof.
The method is
A dispersion medium containing water as a main component, and a first step of preparing a resin cellulose dispersion liquid containing a polyolefin resin and cellulose dispersed in the dispersion medium,
The second step of heating the resin cellulose dispersion while stirring, removing the dispersion medium to obtain a resin cellulose mixture,
Third step of melt kneading the resin cellulose mixture obtained in the second step to obtain a resin composition,
In this order,
A method for producing a resin composition, wherein the second and third steps are carried out by an extruder.   The method for producing a resin composition according to claim 1, wherein the ratio of the polyolefin-based resin in the resin composition is 50 to 99 mass% with respect to 100 mass% of the resin composition.   The resin composition according to claim 1 or 2, wherein the polyolefin-based resin is one or more selected from polyethylene, polypropylene, a copolymer of ethylene and α-olefin, an ethylene-propylene terpolymer, and a mixture thereof. Method of manufacturing things.   The resin according to any one of claims 1 to 3, wherein in the first step, a cellulose dispersion prepared by previously dispersing cellulose in a dispersion medium is added to a polyolefin resin to obtain the resin cellulose dispersion. A method for producing a composition.   The method for producing a resin composition according to any one of claims 1 to 4, wherein more than 50% by mass of the polyolefin resin combined with cellulose in the first step has a pellet shape.   The method for producing a resin composition according to any one of claims 1 to 5, 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.   The method for producing a resin composition according to claim 1, wherein the temperature of the second step is 100 ° C. or higher and lower than 200 ° C. 7.   The method for producing a resin composition according to any one of claims 1 to 7, wherein at least a part of the third step is performed under a reduced pressure state below atmospheric pressure.   The method for producing a resin composition according to claim 1, wherein the first to third steps are continuously performed by the extruder.   The resin composition according to any one of claims 1 to 9, wherein the extruder is a twin-screw extruder having an L / D obtained by dividing a cylinder length (L) by a screw diameter (D) of 40 or more. Production method.

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