WO2021112182A1 - Method for producing resin composition - Google Patents

Abstract

The present invention comprises: a first kneading step wherein cellulose fibers having a weighted average fiber length of from 0.20 mm to 1.50 mm, a compatibilizer resin and urea are fed into a kneading machine and are kneaded therein; and a hot water cleaning step wherein a kneaded product obtained in the first kneading step is cleaned with use of hot water.

Description

Method for manufacturing resin composition

The present invention relates to a method for producing a resin composition containing finely divided cellulose fibers. Furthermore, the present invention relates to a method for producing a resin composition containing finely divided acetylated cellulose fibers.

The fine fibrous cellulose obtained by finely breaking the plant fiber includes microfibril cellulose and cellulose nanofiber, and is a fine fiber having a fiber diameter of about 1 nm to several tens of μm. Fine fibrous cellulose is lightweight, has high strength and high elastic modulus, and has a low coefficient of linear thermal expansion, and thus is suitably used as a reinforcing material for resin compositions.

Fine fibrous cellulose is usually obtained in a state of being dispersed in water, and it is difficult to evenly mix it with a resin or the like. Therefore, attempts have been made to chemically modify the cellulose raw material in order to improve the affinity and miscibility with the resin.

For example, in Patent Document 1, a cellulose raw material in which a part of the hydroxy group of cellulose is replaced with a carbamate group is obtained by heat-treating the cellulose raw material and urea, and the cellulose raw material is refined by mechanical treatment to form fine fibers. Obtaining cellulose. The fine fibrous cellulose obtained by this method has lower hydrophilicity than conventional fine fibrous cellulose and has a high affinity with a resin having low polarity, so that it is highly uniformly dispersed in the resin and has high strength. Gives a complex with. Further, Patent Document 1 discloses that a mixture of the heat-treated cellulose raw material and urea is washed with water or the like to remove unreacted residual urea or the like.

However, there has been a demand for an efficient method for producing a resin composition capable of obtaining a resin molded body having further excellent tensile strength and elongation.

Japanese Unexamined Patent Publication No. 2019-1876

An object of the present invention is to provide an efficient method for producing a resin composition capable of obtaining a resin molded body having excellent tensile strength and elongation.

The present invention provides:
(1) Obtained in the first kneading step and the first kneading step in which cellulose fibers having a weighted average fiber length of 0.20 mm to 1.50 mm, a compatible resin, and urea are put into a kneader and kneaded. A method for producing a resin composition, which comprises a hot water washing step of washing the kneaded product with hot water.
(2) The method for producing a resin composition according to (1), wherein in the hot water washing step, the temperature of the hot water is 50 to 100 ° C. and the washing time is 10 minutes to 24 hours.
(3) The method for producing a resin composition according to (1) or (2), further comprising a second kneading step of kneading the kneaded product after the hot water washing step and the resin for dilution.
(4) The blending amount of the urea to be charged into the kneader in the first kneading step is 10 to 100% by weight with respect to 100% by weight of the total amount of cellulose fibers of cellulose and hemicellulose among the cellulose fibers. The method for producing a resin composition according to (1) to (3).
(5) Of the cellulose fibers charged into the kneader in the first kneading step, the blending amount of the cellulose fibers obtained by combining cellulose and hemicellulose is the total amount of the cellulose fibers, the compatible resin, and the urea. On the other hand, the method for producing a resin composition according to (1) to (4), which is 35 to 85% by weight.
(6) In the first kneading step in which the acetylated cellulose fiber having a weighted average fiber length of 0.20 mm to 1.50 mm, the compatible resin, and the urea are put into a kneader and kneaded, and the first kneading step is performed. A method for producing a resin composition, which comprises a hot water washing step of washing the obtained kneaded product with hot water.
(7) The method for producing a resin composition according to (6), wherein in the hot water washing step, the temperature of the hot water is 50 to 100 ° C. and the washing time is 10 minutes to 24 hours.
(8) The method for producing a resin composition according to (6) or (7), further comprising a second kneading step of kneading the kneaded product after the hot water washing step and the resin for dilution.
(9) The blending amount of the urea to be charged into the kneader in the first kneading step is 100% by weight of the total amount of cellulose fibers including cellulose and hemicellulose that do not contain an acetylated portion of the acetylated cellulose fibers. The method for producing a resin composition according to (6) to (8), which is 10 to 100% by weight based on%.
(10) Of the acetylated cellulose fibers charged into the kneader in the first kneading step, the blending amount of the cellulose fibers including the cellulose not containing the acetylated portion and the hemicellulose is the acetylated cellulose fibers. The method for producing a resin composition according to (6) to (9), which is 35 to 85% by weight based on the total amount of the compatible resin and the urea.

According to the present invention, it is possible to provide an efficient method for producing a resin composition capable of obtaining a resin molded body having excellent tensile strength and elongation.

Hereinafter, the method for producing the resin composition of the present invention will be described. In the present invention, "-" includes a fractional value. That is, "X to Y" includes the values X and Y at both ends thereof.

In the method for producing a resin composition of the present invention (manufacturing method A), a cellulose fiber having a weighted average fiber length (length average fiber length) of 0.20 mm to 1.50 mm, a compatible resin, and urea are kneaded with a kneader. It includes a first kneading step of putting the kneaded material into the kneading and kneading the kneaded product, and a hot water washing step of washing the kneaded product obtained in the first kneading step with hot water.

In the method for producing a resin composition of the present invention (production method B), acetylated cellulose fibers having a weighted average fiber length (length average fiber length) of 0.20 mm to 1.50 mm, a compatible resin, and urea are used. It includes a first kneading step of putting into a kneading machine and kneading, and a hot water washing step of washing the kneaded product obtained in the first kneading step with hot water.

(Cellulose fiber)
The cellulose fibers used in the production method (production method A) of the present invention have a weighted average fiber length (length average fiber length) in the range of 0.2 to 1.5 mm, preferably 0.3 to 1.0 mm. is there. Such cellulose fibers can be obtained, for example, by crushing or beating the cellulose raw material.

(Acetylated cellulose fiber)
The acetylated cellulose fiber used in the production method (production method B) of the present invention is one in which _{the hydrogen atom of the hydroxyl group existing on the cellulose surface of the cellulose raw material is replaced with an acetyl group (CH 3-CO-).} Substitution with an acetyl group enhances hydrophobicity, reduces agglutination during drying, enhances workability, and facilitates dispersion and defibration in the kneaded resin. The degree of acetyl group substitution (DS) of the acetylated cellulose fiber is preferably 0.4 to 1.3, more preferably 0.6 to 1.1 from the viewpoint of workability and maintenance of crystallinity of the cellulose fiber. Adjust to.

(Cellulose raw material)
In the present invention, the cellulose raw material may be any material in the form mainly composed of cellulose, and contains lignocellulose (NUKP), and pulp (bleached or unbleached wood pulp, bleached or unbleached non-wood). Pulp, purified linter, jute, herbaceous pulp such as Kenaf, etc.), natural cellulose such as cellulose produced by microorganisms such as acetic acid bacteria, after dissolving cellulose in some solvent such as copper ammonia solution, morpholin derivative, etc. Reprecipitated regenerated cellulose, fine cellulose obtained by depolymerizing cellulose by subjecting the above cellulose raw material to hydrolysis, alkali hydrolysis, enzymatic decomposition, blasting treatment, mechanical treatment such as vibration ball mill, etc., and various cellulose derivatives (manufacturing) When used in Method B, various cellulose derivatives that do not affect acetylation denaturation) and the like are exemplified.

Lignocellulose is a complex carbohydrate polymer that constitutes the cell wall of plants, and is mainly composed of polysaccharides cellulose and hemicellulose, and lignin, which is an aromatic polymer. The content of lignin can be adjusted by delignin or bleaching the pulp or the like as a raw material.

In the present invention, when pulp is used as the raw material for cellulose, either unbeaten or beaten pulp may be used, but it is preferable to use pulp that has been beaten. As a result, it can be expected that the specific surface area of the pulp will increase and the amount of urea reaction will increase. The degree of beating treatment is preferably 400 mL or less in drainage (C.S.F), and more preferably about 100 mL to 200 mL. If the drainage degree exceeds 400 mL, the effect cannot be exhibited, and if it is less than 100 mL, the strength improving effect is hindered when the reinforcing resin is used because the fibers are shortened due to damage to the cellulose fibers. Further, by performing this beating treatment, the range of the weighted average fiber length (length average fiber length) is 0.2 to 1.5 mm, preferably 0.3 to 1 when the washing treatment and the drying treatment described later are performed. If it falls within the range of 0.0 mm, the crushing step described later may be omitted.

Examples of the beating treatment method include mechanically (mechanically) treating pulp fibers using a known beating machine. As the beating machine, a beating machine usually used for beating pulp fibers can be used, for example, a Niagara beater, a PFI mill, a disc refiner, a conical refiner, a ball mill, a millstone mill, a sand grinder mill, and an impact. Mills, high-pressure homogenizers, low-pressure homogenizers, dyno mills, ultrasonic mills, kanda grinders, attritors, vibration mills, cutter mills, jet mills, disintegrators, household juicer mixers, and mortars. Among them, a Niagara beater, a disc refiner, and a conical refiner are preferable, and a disc refiner and a conical refiner are more preferable.

(Dehydration in beating process)
In the beating process, dehydration may be performed if necessary. As the dehydration method, a pressure dehydration method using a screw press, a vacuum dehydration method by volatilization or the like can be carried out, but the centrifugal dehydration method is preferable from the viewpoint of efficiency. Dehydration is preferably carried out until the solid content in the solvent reaches about 10 to 60%.

(Acetylation reaction)
In the acetylation reaction, the raw material is suspended in an anhydrous aprotic polar solvent capable of swelling the cellulose raw material, for example, N-methylpyrrolidone (NMP) or N, N-dimethylformamide (DMF), and acetic anhydride or acetyl chloride is used. When the reaction is carried out in the presence of a base using acetyl halide or the like, the reaction can be carried out in a short time. As the base used in this acetylation reaction, pyridine, N, N-dimethylaniline, sodium carbonate, sodium hydrogen carbonate, potassium carbonate and the like are preferable, and potassium carbonate is more preferable. It is also possible to carry out the reaction under conditions that do not use an anhydrous aprotic polar solvent or a base by using an excessive amount of an acetylation reagent such as acetic anhydride.

The acetylation reaction is preferably carried out, for example, with stirring at room temperature to 100 ° C. After the reaction treatment, drying under reduced pressure may be performed to remove the acetylation reagent. If the target degree of acetylation substitution has not been reached, the acetylation reaction and subsequent drying under reduced pressure may be repeated an arbitrary number of times.

(Washing)
The acetylated cellulose fiber obtained by the acetylation reaction is preferably subjected to a washing treatment such as water substitution after the acetylation treatment.

(Dehydration in cleaning process)
In the cleaning treatment, dehydration may be performed if necessary. As the dehydration method, a pressure dehydration method using a screw press, a vacuum dehydration method by volatilization or the like can be carried out, but the centrifugal dehydration method is preferable from the viewpoint of efficiency. Dehydration is preferably carried out until the solid content in the solvent reaches about 10 to 60%.

(Dry)
The cellulose fiber used in the production method A of the present invention or the acetylated cellulose fiber used in the production method B of the present invention is used in a pulverization step carried out as necessary after the dehydration in the beating treatment or the washing treatment. It is dried before. The drying process can be performed using, for example, a microwave dryer, a blower dryer or a vacuum dryer (vacuum dryer), but a drum dryer, a paddle dryer, a nouter mixer, and batch drying with stirring blades. A dryer that can dry while stirring is preferable. Drying is preferably carried out as much as possible until the water content of the cellulose fiber or the acetylated cellulose fiber becomes about 0.1 to 10%, preferably about 1 to 5%.

In the present invention, kneading is performed by simultaneously adding urea together with cellulose fibers or acetylated cellulose fibers and a compatible resin. The mechanism of the phenomenon that the strength of cellulose fibers or acetylated cellulose fibers in the resin is improved by this operation has not been clarified at this time, but it is possible to explain a part of it by considering as follows. .. That is, urea is decomposed into ammonia and isocyanic acid when the temperature exceeds 135 ° C., but by kneading urea at the same time as the cellulose fiber or the acetylated cellulose fiber, the unmodified newly emerged from the inside of the cellulose fiber by kneading. It is considered that the hydroxyl group reacts with the generated isocyanic acid to promote the formation of urethane bonds, and it is presumed that the hydrophobicity is enhanced as compared with the cellulose fiber or the acetylated cellulose fiber which is not subjected to the urea treatment. Furthermore, by melt-kneading at the same time as the compatible resin having an acid anhydride, the interaction between the amino group newly introduced by the urea treatment on the surface of the cellulose fiber or the acetylated cellulose fiber and the carboxylic acid of the compatible resin is promoted. , It is considered that it is possible to form a composite of cellulose fibers or acetylated cellulose fibers and a compatible resin more firmly.

In the production method A, the blending amount of urea required to achieve the above mechanism is the amount of cellulose fibers in which cellulose and hemicellulose contained in the cellulose fibers are combined (hereinafter, this is referred to as "cellulose amount"). It is preferably 10 to 100% by weight, more preferably 20 to 100% by weight, still more preferably 30 to 70% by weight, based on 100% by weight.

In the production method B, the blending amount of urea required to achieve the above mechanism is the amount of cellulose fibers including cellulose and hemicellulose contained in the acetylated cellulose fibers (hereinafter referred to as "cellulose amount"). It is preferably 10 to 100% by weight, more preferably 20 to 100% by weight, still more preferably 30 to 70% by weight, based on 100% by weight.

(Compatible resin)
In the present invention, kneading is performed by simultaneously adding a compatible resin together with cellulose fibers or acetylated cellulose fibers and urea. The compatible resin has a function of uniformly mixing the cellulose fibers or acetylated cellulose fibers having different hydrophobicities with the diluting resin and enhancing the adhesion. As the compatible resin used in the present invention (hereinafter, may be referred to as "master batch resin"), a low molecular weight dicarboxylic acid capable of forming an acid anhydride such as maleic anhydride, succinic acid, and glutaric acid is used. , Polypropylene, polyethylene, and other polymer resins that are present on the polyolefin chain. Among them, maleic anhydride-modified polypropylene (MAPP) to which maleic acid is added and maleic anhydride-modified polyethylene (MAPE) as the main components are used as main components. It is preferably used together with a diluting resin.

Factors that determine the characteristics of the compatible resin are the amount of dicarboxylic acid added and the weight average molecular weight of the polyolefin resin that is the base material. A polyolefin resin having a large amount of dicarboxylic acid added enhances compatibility with a hydrophilic polymer such as cellulose, but the molecular weight of the resin becomes small during the addition process, and the strength of the molded product decreases. As an optimum balance, the amount of the dicarboxylic acid added is 20 to 100 mgKOH / g, more preferably 45 to 65 mgKOH / g. When the amount added is small, the number of points that interact with the urea-derived amino group in the resin is reduced. Further, when the addition amount is large, the strength as a reinforced resin is not achieved due to self-aggregation due to hydrogen bonds between carboxyl groups in the resin and a decrease in the molecular weight of the olefin resin as a base material due to an excessive addition reaction. The molecular weight of the polyolefin resin is preferably 35,000 to 250,000, more preferably 50,000 to 100,000. If the molecular weight is smaller than this range, the strength of the resin is lowered, and if it is larger than this range, the viscosity at the time of melting is greatly increased, the workability at the time of kneading is lowered, and molding defects are caused.

The amount of the compatible resin having the above characteristics added is preferably 10 to 70% by weight, more preferably 20 to 50% by weight, based on the amount of cellulose. If the addition amount exceeds 70% by weight, it is considered that the introduction of urea-derived isocyanic acid into the cellulose fiber is inhibited and the formation of a complex of the compatibilizer and urea is promoted, and the effect of the present invention is not exhibited.

Further, as the compatible resin, one type may be used alone, or two or more types may be used as a mixed resin. When used as a graft body of one or more kinds of polymers and polyolefin, the polyolefin resin constituting the graft body is not particularly limited, but polyethylene, polypropylene, polybutene or the like may be used from the viewpoint of easy production of the graft body. Can be used.

(1st kneading process pretreatment-crushing process)
In the present invention, a pulverization step may be provided before the first kneading step described later. By using the cellulose fibers or acetylated cellulose fibers crushed in the crushing step, when the cellulose fibers or the acetylated cellulose fibers are put into the kneader, the fiber lumps of the cellulose fibers or the acetylated cellulose fibers are in a state of being appropriately unraveled, and the charging port (chute portion). It is possible to suppress the occurrence of bridge (clogging) and poor biting of pulp into the screw.

The cellulose fiber or acetylated cellulose fiber crushed in the crushing step is preferably used through a screen, and it is preferable to use a screen having a diameter of 1 mm or more and 5 mm or less, preferably a diameter of 3 mm or more and 5 mm or less. The weighted average fiber length (length average fiber length) of the cellulose fiber or the acetylated cellulose fiber thus obtained is preferably about 0.20 to 1.5 mm, more preferably 0.30 to 1.0 mm. Is.

As the cellulose fiber or acetylated cellulose fiber to be crushed in the crushing step, it is preferable to use a dried one from the viewpoint of reducing the drying load at the time of kneading.

(1st kneading process)
In the first kneading step of the production method A of the present invention, cellulose fibers having a weighted average fiber length of 0.20 to 1.50 mm, preferably 0.30 to 1.00 mm, a compatible resin, and urea are used as essential components. At the same time, it is put into a kneader and melt-kneaded. If necessary, an optional component such as an antioxidant may be added to the kneader at the same time as the above essential component. The weighted average fiber length (length average fiber length) of the cellulose fibers can be measured using a fiber tester (manufactured by L & W) or the like. When putting it into the kneading machine, various commercially available feeders and side feeders can be used. Additives such as compatible resin, urea, and antioxidant used as needed, if powdered in advance, add cellulose fiber, compatible resin, urea, antioxidant, etc. before charging. The agent can be mixed and charged by a commercially available mixer or the like. Even when the compatible resin or the like is not powdered, it can be charged by preparing a plurality of feeders, such as a feeder for pellets and a feeder for cellulose fibers. In the first kneading step, the blending amount of the cellulose fiber content of the cellulose fiber charged into the kneading machine is preferably 35 to 85% by weight with respect to the total amount of the cellulose fiber, the compatible resin, and the urea, and is 40. More preferably, it is in the amount of ~ 65% by weight.

In the first kneading step of the production method B of the present invention, acetylated cellulose fibers having a weighted average fiber length of 0.20 to 1.50 mm, preferably 0.30 to 1.00 mm, compatible resins, and compatible resins are essential components. Urea is put into the kneader at the same time to perform melt kneading. If necessary, an optional component such as an antioxidant may be added to the kneader at the same time as the above essential component. The weighted average fiber length (length average fiber length) of the acetylated cellulose fiber can be measured using a fiber tester (manufactured by L & W) or the like. When putting it into the kneading machine, various commercially available feeders and side feeders can be used. Additives such as compatible resins, ureas, and antioxidants used as needed, if powdered in advance, are acetylated cellulose fibers, compatible resins, ureas, antioxidants, etc. before injection. Additives can be mixed and added using a commercially available mixer or the like. Even when the compatible resin or the like is not powdered, it can be charged by preparing a plurality of feeders, such as a feeder for pellets and a feeder for acetylated cellulose fibers. In the first kneading step, the blending amount of the cellulose fiber content of the acetylated cellulose fiber charged into the kneading machine shall be 35 to 85% by weight with respect to the total amount of the acetylated cellulose fiber, the compatible resin, and the urea. Is preferable, and 40 to 65% by weight is more preferable.

(Kneader)
As the kneading machine used in the first kneading step of the present invention, a kneading machine capable of melt-kneading a compatible resin and urea and having a strong kneading power for promoting nanonization of cellulose fibers or acetylated cellulose fibers is preferable. It is desirable to use a multi-screw kneader such as a bi-screw kneader or a 4-screw kneader, and to include a plurality of kneadings, rotors, etc. in the parts constituting the screw. As long as the kneading power equivalent to the above can be secured, for example, a kneading machine such as a bench roll, a Banbury mixer, a kneader, or a planetary mixer may be used. Further, in order to remove water and volatile urea attached to the cellulose fibers, it is preferable to knead a part or all of the inside of the kneader barrel under reduced pressure.

The set temperature for melt-kneading can be adjusted according to the melt temperature of the compatible resin to be used. When maleic anhydride-modified polypropylene suitable for the present invention is used as the compatible resin, the temperature is preferably 135 ° C. or higher in order to promote the decomposition of urea, and the compatible resin has a dicarboxylic acid residue capable of forming an acid anhydride. It is more preferable that the temperature is 160 ° C. or higher, which is melted and the terminal of a part of the dicarboxylic acid residue is closed by dehydration. Isocyanic acid is generated from urea by the above temperature setting, and forms a urethane bond with an unmodified hydroxyl group on the cellulose fiber. As a result, the introduction of amino groups on the cellulose fibers is achieved, and it becomes possible to promote the interaction with the compatible resin. Further, at the above temperature, the dicarboxylic acid residue in the compatible resin is closed to form an acid anhydride, so that an esterification reaction with the cellulose fiber or the acetylated cellulose fiber occurs to form a stronger resin composite. Is possible. On the other hand, when the kneading temperature exceeds 200 ° C., the polypropylene resin as the base material begins to deteriorate and the strength decreases.

In the present invention, the cellulose fibers or acetylated cellulose fibers, compatibilized resin and urea charged into the kneader in the first kneading step are melt-kneaded, and at least a part of the cellulose fibers is melt-kneaded due to the shearing force generated during the melt-kneading. Alternatively, the acetylated cellulose fiber is defibrated to prepare a cellulose nanofiber or a resin composition containing the acetylated cellulose nanofiber.
The cellulose nanofibers and the acetylated cellulose nanofibers are preferably fine fibers having a fiber diameter of about 1 to 1000 nm and an aspect ratio of 100 or more. The resin composition according to the present invention may be dominated by the cellulose nanofibers, and the resin composition may contain unfibrillated fibers.

(Antioxidant)
In the present invention, when the melting point of the diluting resin described later becomes a high temperature, from the viewpoint of suppressing the decrease in strength due to the decomposition of pulp, in addition to the essential components, an antioxidant is simultaneously added to the kneader in the first kneading step. It is preferable to add and melt and knead. For example, when polyamide 6 (PA6) (melting point: about 230 ° C.) is used as the dilution resin, it is preferable to add an antioxidant. The antioxidant is not particularly limited, and examples thereof include hindered phenol-based, hindered amine-based, phosphorus-based, and sulfur-based, and it is preferable to use hindered phenol-based.

The amount of the antioxidant added is not particularly limited as long as the effect of the present invention is not impaired, but since the strength is lowered by excessive addition, the amount of the antioxidant added is 0. It is preferably about 1 to 3% by weight, more preferably 0.5 to 2% by weight.

(Hot water cleaning process)
The method for producing a resin composition of the present invention includes a hot water washing step of washing the kneaded product obtained in the above first kneading step with hot water. By washing the above-mentioned kneaded product with hot water, residual urea in the kneaded product and urea-derived by-products (biuret, cyanuric acid, melamine, etc.) that can be slightly produced in the kneading process can be roughly removed. It is considered that the aggregation of fibers and the like caused by residual urea and its by-products is eliminated. Therefore, the resin molded body obtained by using the kneaded product after washing is excellent in tensile strength and elongation.

The kneaded product obtained in the first kneading step may be washed with hot water as long as it can be stirred or dispersed. For example, stirring by a three-one motor, an agitator, a homomixer, or a homogenizer can be used. , Known stirrers or dispersers, such as mixers and the like.

The temperature of the hot water used for washing is 50 to 100 ° C., preferably 60 to 90 ° C., more preferably 60 to 80 ° C. from the viewpoint of improving the solubility of residual urea and its by-products. The total cleaning time is preferably 10 minutes to 24 hours, more preferably 0.5 hours to 5 hours, and even more preferably 1 hour to 3 hours in consideration of efficiency. From the viewpoint of chemical equilibrium, hot water is exchanged 0 to 10 times, preferably 1 to 5 times within the washing time. The weight% of the kneaded product obtained in the first kneading step at the time of washing is preferably 0.1 to 50% by weight, more preferably 0.1 to 15% by weight, from the viewpoint of chemical equilibrium. Further, it is preferable to wash until the amount of residual urea is less than 1%, particularly less than 0.1%. Since the thermal decomposition start temperature of urea is 135 ° C., the amount of residual urea can be determined from the weight loss when heated at 140 ° C. for 270 minutes, for example.

In the method for producing a resin composition of the present invention, ring closing and ring opening prevention of the modifying group in the compatibilizer in the second kneading step, decomposition prevention of cellulose fibers or acetylated cellulose fibers and the resin for dilution by the remaining water, and kneading are performed. From the viewpoint of reducing the drying load at the time, it is preferable to dry and use the kneaded product washed in the above hot water washing step. The drying process can be performed using, for example, a microwave dryer, a blower dryer, or a vacuum dryer, but a drum dryer, a paddle dryer, a nouter mixer, a batch dryer with stirring blades, or the like is used for stirring. A dryer that can dry while still is preferable. The drying is preferably carried out until the water content of the kneaded product reaches about 0.1 to 5%.

(Second kneading process)
The method for producing a resin composition of the present invention is a kneaded product obtained in the above-mentioned first kneading step, which is further washed in a hot water washing step and a second kneading step in which a resin for dilution is kneaded. It may be further included. When the second kneading step is included, the kneaded product obtained in the first kneading step and further washed in the hot water washing step can be used as a masterbatch.

(Resin for dilution)
As the diluting resin used in the present invention, the following general thermoplastic resins having a melting temperature of 250 ° C. or lower can be used.

That is, polyolefin resin, polyamide resin, polyvinyl chloride, polystyrene, polyvinylidene chloride, fluororesin, (meth) acrylic resin, polyester, polylactic acid, copolymer resin of lactic acid and ester, polyglycolic acid, acrylonitrile-butadiene- A styrene copolymer (ABS resin), polyphenylene oxide, polyurethane, polyacetal, vinyl ether resin, polysulfone resin, cellulose resin (triacetylated cellulose, diacetylated cellulose, etc.) and the like can be used.

As the polyolefin resin, polyethylene, polypropylene (hereinafter, also referred to as “PP”), ethylene-propylene copolymer, polyisobutylene, polyisoprene, polybutadiene, etc. can be used, and from the viewpoint of interaction with the compatible resin. Therefore, when MAPP is used, polypropylene is preferably used, and when MAPE is used, polyethylene is preferably used.

In addition, the polyamide resin (PA) is expected to interact with the hydroxyl groups and acetyl groups of cellulose that are not affected by urea, and can be preferably used. As PA, polyamide 6 (nylon 6, PA6), polyamide 11 (nylon 11, PA11), polyamide 12 (nylon 12, PA12), polyamide 66 (nylon 66, PA66), polyamide 46 (nylon 46, PA46), polyamide Aromatic PA consisting of aliphatic PAs such as 610 (nylon 610, PA610) and polyamide 612 (nylon 612, PA612), aromatic diamines such as phenylenediamine, and aromatic dicarboxylic acids such as terephthaloyl chloride and isophthaloyl chloride or derivatives thereof. And so on. From the viewpoint of high affinity with cellulose fibers and cellulose nanofibers, it is preferable to use an aliphatic PA, more preferably PA6, PA11 and PA12, and particularly preferably PA6. Further, as the polyamide resin, one type may be used alone, or two or more types of polyamide resins may be mixed and used.

When the kneaded product washed in the hot water washing step is used as a masterbatch, a resin composition further containing a dilution resin can be obtained by adding a dilution resin to the masterbatch and melt-kneading. When the resin for dilution is added and melt-kneaded, both components may be mixed at room temperature without heating and then melt-kneaded, or mixed while heating and melt-kneaded.

As the kneading machine when the resin for dilution is added and melt-kneaded, the same kneading machine as that used in the first kneading step described above can be used. Further, the melt-kneading temperature can be adjusted according to the compatibilizing resin used in the first kneading step. The set heating temperature during melt kneading is preferably a minimum processing temperature of about ± 20 ° C recommended by the thermoplastic resin supplier, but for short-term kneading, cellulose fibers or acetylated cellulose fibers can be kneaded up to 300 ° C. It is also possible to leave the shape of. However, from the viewpoint of facilitating the maintenance of the molecular weight of the resin, it is preferable to knead at a temperature near the melting point of the resin. Therefore, when polypropylene is used as the dilution resin, the melt-kneading temperature may be 140 to 230 ° C. It is preferably 160 to 200 ° C., more preferably 160 to 200 ° C. When the polyamide 6 is used as the dilution resin, the melt-kneading temperature is preferably 140 to 240 ° C, more preferably 160 to 220 ° C. By setting the mixing temperature in this temperature range, the cellulose fiber or the acetylated cellulose fiber and the resin can be uniformly mixed.

The resin composition produced by the production method of the present invention further includes, for example, surfactants; polysaccharides such as starches and alginic acid; natural proteins such as gelatin, gelatin and casein; tannins, zeolites, ceramics, metal powders and the like. Inorganic compounds; colorants; plastics; fragrances; pigments; flow regulators; leveling agents; conductive agents; antistatic agents; ultraviolet absorbers; ultraviolet dispersants; deodorants, antioxidants, etc. You may. As the content ratio of any additive, it may be appropriately contained as long as the effect of the present invention is not impaired.

(Resin composition)
The resin composition obtained by the production method of the present invention may be a kneaded product (master batch) kneaded in the first kneading step and washed in the hot water washing step, or kneaded in the first kneading step and hot water. The resin composition obtained in the second kneading step of kneading the kneaded product (master batch) washed in the washing step and the resin for dilution may be used.

According to the present invention, it is possible to provide a method for producing a resin composition capable of obtaining a resin molded body having excellent tensile strength and elongation.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

(Measurement method of acetyl group substitution degree (DS))
(Measurement of DS by back titration method)
A sample of acetylated cellulose fibers was dried and 0.5 g (A) was accurately weighed. 75 mL of ethanol and 50 mL (0.025 mol) (B) of 0.5 N NaOH were added thereto, and the mixture was stirred for 3 to 4 hours. This was filtered, washed with water, dried, and FT-IR measurement of the sample on the filter paper was performed, and it was confirmed that the absorption peak based on the carbonyl of the ester bond had disappeared, that is, the ester bond had been hydrolyzed.
The filtrate was used for the following back titration.
The filtrate contains sodium acetate salt resulting from hydrolysis and excess NaOH added. This NaOH neutralization titration was performed using 1N HCl (phenolphthalein was used as an indicator).

0.025 mol (B)-(Number of moles of HCl used for neutralization)
= Number of moles of acetyl group ester-bonded to hydroxyl group such as cellulose (C)
(Cellulose repeating unit molecular weight 162
× Number of moles of cellulose repeating unit (unknown (D))
+ (Molecular weight of acetyl group 43 × (C))
= Weighed sample 0.5 g (A)
From the above formula, the number of moles (D) of the repeating unit of cellulose was calculated.

DS was calculated by the following formula.
・ DS = (C) / (D)

(Measurement of tensile strength and tensile strain)
The resin compositions obtained in Examples and Comparative Examples were put into a pelletizer to obtain a pellet-shaped resin molded product. 150 g of pellet-shaped resin molded product is put into a small molding machine (“MC15” manufactured by Xplore Instruments), and the temperature of the heating cylinder (cylinder) is 200 ° C. when the dilution resin is PP, and when the dilution resin is PA6. Was 250 ° C., and the mold temperature was 40 ° C., and a dumbbell mold test piece (type A12, JIS K 7139) was molded. Using a precision universal testing machine (“Autograph AG-Xplus” manufactured by Shimadzu Corporation), the obtained test piece had a test speed of 1 mm / min, an initial distance between marked lines of 30 mm, and tensile strength (yield point). Strength) and tensile strain (strain until breaking, elongation) were measured. Of the measured values, the ratio of the measured values of each sample when the tensile strength values of PP and PA6, which are dilution resins, are set to 100, is used as the reinforcement rate, and the results are shown in Tables 1 and 2. When cellulose fibers are used and PP is used as the dilution resin, a tensile strength of 112 or more indicates that the strength is excellent. Further, when PA6 is used as the dilution resin using cellulose fibers, it is shown that the tensile strength is excellent when the tensile strength is 150 or more. When acetylated cellulose fibers are used and PP is used as the dilution resin, a tensile strength of 125 or more indicates that the strength is excellent. Further, when PA6 is used as the dilution resin by using the acetylated cellulose fiber, it is shown that the tensile strength is excellent when the tensile strength is 175 or more. The larger the tensile strain value, the better the elongation.

(Crusher used to crush acetylated cellulose fibers)
"UGO3-280XKFT" made by Horai Co., Ltd.
Rotary blade type: Open straight cutter

(Kneader and operating conditions used to manufacture masterbatch and resin composition)
"MFU15TW-45HG-NH" twin-screw kneader manufactured by Technobel Co., Ltd. Screw diameter: 15 mm, L / D: 45, processing speed: 300 g / hour The screw rotation speed was 200 rpm.

(Material used for manufacturing masterbatch and resin composition)
(A) Cellulose fiber or acetylated cellulose fiber (b) Compatible resin (resin for masterbatch)
-Maleic anhydride-modified polypropylene (MAPP): (Toyobo Co., Ltd. Toyo Tuck PMA-H1000P: Addition of dicarboxylic acid 57 mgKOH / g)
(C) Urea: (manufactured by Wako Pure Chemical Industries, Ltd.)
(D) Diluting resin-Polypropylene (PP): (PP MA04A manufactured by Japan Polypropylene Corporation)
Polyamide 6 (PA6): (PA6 1013FB manufactured by Ube Industries, Ltd., melting point: about 230 ° C.)
(E) Antioxidant: (Irganox 1010 manufactured by BASF)

(Example 1)
(Preparation of cellulose fiber)
20 kg (solid content 10 kg) of hydrous coniferous unbleached kraft pulp (NUKP) that had been beaten to 150 mL of CSF was put into a stirrer (“FM150L” manufactured by Nippon Coke Industries Co., Ltd.), and then stirring was started. Then, it was dehydrated under reduced pressure at 80 ° C. The water content of the obtained cellulose fiber was measured with an infrared moisture meter. The water content was 1.7% by weight. Further, the fiber length of the cellulose fiber was measured by a fiber tester (manufactured by L & W), and the weighted average fiber length was 0.90 mm.

(Manufacturing of masterbatch)
Cellulose fibers subjected to the above beating treatment (438 g as an absolute dried product, of which the amount of cellulose obtained by combining cellulose and hemicellulose: 400 g), powdery compatible resin (MAPP: 120 g), and powdered urea (280 g:: A blending amount of 70% with respect to the amount of cellulose) was placed in a polyethylene bag and shaken to mix. 838 g of the obtained mixture was put into a kneader using a feeder (manufactured by Technobel Co., Ltd.) attached to the above-mentioned twin-screw kneader, and kneaded at 180 ° C. to produce a masterbatch.

(Hot water washing)
800 g of the masterbatch obtained above was washed with 10 L of hot water at 65-80 ° C. for 2 hours. Hot water exchange was performed once during cleaning. Stirring was performed using a Primix Automixer 40 type. The temperature was maintained by a water bath. After washing, the masterbatch was put into a dryer and dried at 105 ° C. overnight (or until it became constant).

(Manufacturing of resin composition)
The master batch and the diluting resin (PP) obtained after washing with hot water and drying have the same amount of cellulose fibers derived from the cellulose fibers as the resin (compatible resin and the diluting resin), the cellulose fiber, and the urea. The resin composition was obtained by mixing with a composition of 10% of the total amount of the above and kneading at 180 ° C. with the twin-screw kneader.

(Comparative Example 1)
The resin composition was produced in the same manner as in Example 1 except that the masterbatch was produced in the same manner as in Example 1, the obtained masterbatch was used as it was without washing with hot water and then drying. It was.

(Comparative Example 2)
The resin composition was produced in the same manner as in Example 1 except that the masterbatch was washed with hot water and then dried as a resin composition having a fiber content of 10% when the production was completed.

(Example 2)
Examples except that the amount of urea added during masterbatch production was changed to 50% of the amount of cellulose (200 g) and the antioxidant was added in an amount of 10% (40 g) of the amount of cellulose. The master batch was produced by kneading in the same manner as in 1. Further, the obtained masterbatch was the same as in Example 1 except that the masterbatch was changed to 750 g and the amount of hot water was changed to 9.38 L in order to unify the ratio of the masterbatch weight and hot water at the time of washing. Washing and subsequent drying were performed.

(Manufacturing of resin composition)
The master batch and the diluting resin (PA6) obtained after washing with hot water and drying have the same amount of cellulose fibers derived from the cellulose fibers as the resin (compatible resin and the diluting resin), the cellulose fibers, and the urea. The mixture was mixed with a composition of 10% of the total amount of the antioxidant and the antioxidant, and kneaded at 210 ° C. with the twin-screw kneader to obtain a resin composition.

(Comparative Example 3)
The resin composition was produced in the same manner as in Example 2 except that the masterbatch was produced in the same manner as in Example 2, the obtained masterbatch was used as it was without washing with hot water and then drying. It was.

　　　　　　　　　　　　　　　　　 

　　　　　　　　　　　　　　　　　 

As shown in Table 1, the first kneading step in which the cellulose fiber of the present invention, the compatible resin, and urea are put into a kneading machine and kneaded, and the kneaded product obtained in the first kneading step are heated. According to a method for producing a resin composition (manufacturing method A) including a hot water cleaning step of washing with water, a comparative example having a tensile strength superior to that of a single resin and not having a hot water cleaning step. 1. It was possible to obtain a resin composition that gives an excellent molded product with improved elongation even when the same resin is used as compared with Comparative Example 3.

(Example 3)
(Preparation of acetylated cellulose fiber)
20 kg (solid content 10 kg) of hydrous coniferous unbleached kraft pulp (NUKP) that had been beaten to 150 mL of CSF was put into a stirrer (“FM150L” manufactured by Nippon Coke Industries Co., Ltd.), and then stirring was started. Then, it was dehydrated under reduced pressure at 80 ° C. Then, 4.0 kg of acetic anhydride was added, and the mixture was reacted at 80 ° C. for 2 hours. After the reaction, it was washed with water to obtain acetylated cellulose fibers (acetylation-modified NUKP). Then, the acetylated cellulose fiber was put into a dryer and dried under reduced pressure at 60 to 70 ° C. The water content of the obtained acetylated cellulose fiber was measured with an infrared moisture meter. The water content was 2.3% by weight. The degree of acetyl group substitution (DS) of the acetylated cellulose fiber was 0.7. The fiber length of the acetylated cellulose fiber was measured with a fiber tester (manufactured by L & W), and the weighted average fiber length was 0.664 mm.

(Manufacturing of masterbatch)
Acetylated cellulose fiber subjected to the above beating treatment (483.7 g as an absolute dried product, of which the total amount of cellulose containing cellulose and hemicellulose not containing an acetylated portion: 360 g), a powdery compatible resin (MAPP) : 108 g) and powdered urea (252 g: 70% of the amount of cellulose) were placed in a polyethylene bag and shaken to mix. 843.7 g of the obtained mixture was put into a kneader using a feeder (manufactured by Technobel Co., Ltd.) attached to the above-mentioned twin-screw kneader, and kneaded at 180 ° C. to produce a masterbatch.

(Hot water washing)
800 g of the masterbatch obtained above was washed with 10 L of hot water at 65-80 ° C. for 2 hours. Hot water exchange was performed once during cleaning. Stirring was performed using a Primix Automixer 40 type. The temperature was maintained by a water bath. After washing, the masterbatch was put into a dryer and dried at 105 ° C. overnight (or until it became constant).

(Manufacturing of resin composition)
The master batch and the diluting resin (PP) obtained after washing with hot water and drying have the same amount of cellulose fibers derived from the acetylated cellulose fibers as the resin (compound resin and the diluting resin) and the acetylated cellulose. The mixture was mixed so as to have a composition of 10% of the total amount of the fiber and urea, and kneaded at 180 ° C. with the twin-screw kneader to obtain a resin composition.

(Example 4)
The amount of urea added during the production of the masterbatch was changed to 50% of the amount of cellulose (180 g), and the masterbatch weighed 750 g and the amount of hot water was unified in order to unify the ratio of the masterbatch weight and hot water during washing. The resin composition was produced in the same manner as in Example 3 except that it was changed to 9.38 L.

(Comparative Example 4)
The resin composition was produced in the same manner as in Example 3, except that the masterbatch was produced in the same manner as in Example 3, the obtained masterbatch was used as it was without washing with hot water and then drying. It was.

(Comparative Example 5)
After acetylation using NUKP without beating treatment, the crushing treatment was carried out by the above crusher, and then the screen was passed through a screen having a diameter of 3 mm, and the masterbatch was washed with hot water and then dried to have a fiber content of 10%. The resin composition was produced in the same manner as in Example 3 except that the resin composition was produced when the production was completed. At this time, the weighted average fiber length of the acetylated cellulose fiber was 0.761 mm.

(Example 5)
At the time of producing the masterbatch, the masterbatch was produced by kneading in the same manner as in Example 4 except that an antioxidant was further added in an amount (36 g) of 10% with respect to the amount of cellulose. Further, the obtained master batch was washed with hot water and then dried in the same manner as in Example 4.

(Manufacturing of resin composition)
The master batch and the diluting resin (PA6) obtained after washing with hot water and drying have the same amount of cellulose fibers derived from the acetylated cellulose fibers as the resin (compatible resin and the diluting resin) and the acetylated cellulose. The mixture was mixed with a composition of 10% of the total amount of the fiber, urea, and the antioxidant, and kneaded at 210 ° C. with the twin-screw kneader to obtain a resin composition.

(Comparative Example 6)
The resin composition was produced in the same manner as in Example 5, except that the masterbatch was produced in the same manner as in Example 5, the obtained masterbatch was used as it was without washing with hot water and then drying. It was.

　　　　　　　　　　　　　　　　　 

　　　　　　　　　　　　　　　　　 

As shown in Table 2, the first kneading step in which the acetylated cellulose fiber of the present invention, the compatible resin, and urea are put into a kneading machine and kneaded, and the kneaded product obtained in the first kneading step are mixed. According to a method for producing a resin composition (manufacturing method B), which comprises a hot water washing step of washing with hot water, Comparative Example 4 having a high tensile strength and no hot water washing step, comparison It was possible to obtain a resin composition that gives an excellent molded product with improved elongation even when the same resin is used as compared with Example 6.

Claims (10)

The first kneading step in which cellulose fibers having a weighted average fiber length of 0.20 mm to 1.50 mm, a compatible resin, and urea are put into a kneader and kneaded.
A method for producing a resin composition, which comprises a hot water washing step of washing the kneaded product obtained in the first kneading step with hot water. The method for producing a resin composition according to claim 1, wherein in the hot water washing step, the temperature of the hot water is 50 to 100 ° C. and the washing time is 10 minutes to 24 hours. The method for producing a resin composition according to claim 1 or 2, further comprising a second kneading step of kneading the kneaded product after the hot water washing step and the resin for dilution. The claim that the blending amount of the urea to be charged into the kneader in the first kneading step is 10 to 100% by weight with respect to 100% by weight of the total amount of cellulose fibers of cellulose and hemicellulose among the cellulose fibers. The method for producing a resin composition according to any one of 1 to 3. Of the cellulose fibers charged into the kneader in the first kneading step, the blending amount of the cellulose fibers obtained by combining cellulose and hemicellulose is based on the total amount of the cellulose fibers, the compatible resin, and the urea. The method for producing a resin composition according to any one of claims 1 to 4, which is 35 to 85% by weight. The first kneading step in which acetylated cellulose fibers having a weighted average fiber length of 0.20 mm to 1.50 mm, a compatible resin, and urea are put into a kneader and kneaded.
A method for producing a resin composition, which comprises a hot water washing step of washing the kneaded product obtained in the first kneading step with hot water. The method for producing a resin composition according to claim 6, wherein in the hot water washing step, the temperature of the hot water is 50 to 100 ° C. and the washing time is 10 minutes to 24 hours. The method for producing a resin composition according to claim 6 or 7, further comprising a second kneading step of kneading the kneaded product after the hot water washing step and the resin for dilution. The blending amount of the urea to be charged into the kneader in the first kneading step is 100% by weight of the total amount of cellulose fibers including cellulose and hemicellulose that do not contain an acetylated portion of the acetylated cellulose fibers. The method for producing a resin composition according to any one of claims 6 to 8, which is 10 to 100% by weight. Of the acetylated cellulose fibers charged into the kneader in the first kneading step, the blending amount of the cellulose fibers including the cellulose not containing the acetylated portion and the hemicellulose is the acetylated cellulose fibers and the compatibility. The method for producing a resin composition according to any one of claims 6 to 9, which is 35 to 85% by weight based on the total amount of the resin and the urea.