JP7151024B1 - Fiber-reinforced resin masterbatch, resin composition, method for producing fiber-reinforced resin masterbatch, and method for producing resin composition - Google Patents

Abstract

Pulp fiber (A) having a Canadian standard freeness of 0 mL or more and 600 mL or less and a lignin content of 1% by mass or more and 30% by mass or less, and a thermoplastic thermoplastic that is modified with a hydrophilic functional group and has a melting point as a base material A thermoplastic resin (B1) having a melting point of the resin (M) or lower, and a thermoplastic resin (B1) not modified with a hydrophilic functional group and having a melting point of the base thermoplastic resin (M) or lower ( B2) and urea or a derivative thereof (C), and satisfy the following formulas (a) and (b) at the same time. Formula (a): 0 < (B2 mass) / {(A mass) × (100-lignin content) / 100} ≤ (B1 mass) / {(A mass) × (100-lignin content) / 100} formula ( b): 0<(B2 mass)/{(A mass)×(100-lignin content)/100}≦(C mass)/{(A mass)×(100-lignin content)/100}

Description

TECHNICAL FIELD The present invention relates to a fiber-reinforced resin masterbatch, a resin composition, a method for producing a fiber-reinforced resin masterbatch, and a method for producing a resin composition.

Fine fibrous cellulose obtained by finely disintegrating plant fibers includes microfibril cellulose and cellulose nanofibers, and is fine fibers with a fiber diameter of about 1 nm to several tens of μm. Fine fibrous cellulose is lightweight, has high strength and high modulus of elasticity, and has a low coefficient of linear thermal expansion, and is therefore suitably used as a reinforcing material for resin compositions.

However, since fine fibrous cellulose is hydrophilic while resin is hydrophobic, there is a problem in the dispersibility of fine fibrous cellulose when using fine fibrous cellulose as a reinforcing material for resin. rice field.

In Patent Document 1, by heat-treating a cellulose raw material and urea, a cellulose raw material in which a part of the hydroxy groups of cellulose is substituted with a carbamate group is obtained, and this is finely refined by mechanical treatment to obtain fine fibrous cellulose. It has gained. The fine fibrous cellulose obtained by this method has a freeness of 100 mL or less, is less hydrophilic than conventional fine fibrous cellulose, and has a high affinity with low-polarity resins. Disperse with high uniformity and provide a resin composition having high tensile strength.

However, the resin composition obtained by the method of Patent Document 1 is not sufficiently dispersed during dilution kneading, and there is room for improvement in terms of tensile strength and tensile modulus. In addition, the resin composition obtained by the method of Patent Document 1 has a problem of generation of black spots due to aggregates derived from cellulose.

JP 2019-1876 A

The present invention provides a fiber-reinforced resin masterbatch capable of obtaining a resin composition having a high tensile modulus and further suppressing the occurrence of black spots due to cellulose-derived aggregates, and a resin composition using the same. intended to provide Another object of the present invention is to provide a method for producing this fiber-reinforced resin masterbatch and a method for producing a resin composition.

The present invention provides the following.
(1) A fiber-reinforced resin masterbatch for a thermoplastic resin (M), a pulp fiber (A) having a Canadian standard freeness of 0 mL or more and 600 mL or less and a lignin content of 1% by mass or more and 30% by mass or less; , a thermoplastic resin (B1) that has been modified with a hydrophilic functional group and has a melting point lower than the melting point of the thermoplastic resin (M) serving as the base material, and a thermoplastic resin (B1) that has not been modified with a hydrophilic functional group and has a melting point of , a thermoplastic resin (B2) having a melting point or less of the thermoplastic resin (M) serving as the base material, and urea or a derivative thereof (C), and the following formula (a) and formula (b) are simultaneously expressed Satisfying fiber reinforced resin masterbatch.
Formula (a): 0 < (B2 mass) / {(A mass) × (100-lignin content) / 100} ≤ (B1 mass) / {(A mass) × (100-lignin content) / 100}
Formula (b): 0 < (B2 mass) / {(A mass) × (100-lignin content) / 100} ≤ (C mass) / {(A mass) × (100-lignin content) / 100}
(2) The fiber-reinforced resin masterbatch according to (1), which further satisfies the following formula (c).
Formula (c): (C mass) / {(A mass) × (100-lignin content) / 100} <0.8
(3) The fiber-reinforced resin masterbatch according to (1) or (2), wherein the pulp fibers (A) further have a water content of 1% or more and 90% or less.
(4) The fiber-reinforced resin masterbatch according to (1) to (3), wherein the modification of the thermoplastic resin (B1) is acid modification.
(5) The fiber-reinforced resin masterbatch according to (1) to (4), wherein at least one of the thermoplastic resin (B1) and the thermoplastic resin (B2) is a block copolymer.
(6) The fiber-reinforced resin masterbatch according to (1) to (5), wherein at least one of the thermoplastic resin (B1) and the thermoplastic resin (B2) is polyolefin.
(7) The fiber-reinforced resin masterbatch according to (1) to (6), wherein the thermoplastic resin (B1) is acid-modified polyolefin and the thermoplastic resin (B2) is polyethylene.
(8) The fiber-reinforced resin masterbatch according to (1) to (7), wherein the thermoplastic resin (M) is polyolefin.
(9) A resin composition obtained by kneading the fiber-reinforced resin masterbatch according to (1) to (8) and the thermoplastic resin (M).
(10) A method for producing a fiber-reinforced resin masterbatch for a thermoplastic resin (M), comprising the following steps (i) and (ii), wherein the obtained fiber-reinforced resin masterbatch is represented by the following formula (a) and a method for producing a fiber-reinforced resin masterbatch, which simultaneously satisfies the formula (b).
Step (i): pulp fibers (A) having a Canadian standard freeness of 0 mL or more and 600 mL or less and a lignin content of 1% by mass or more and 30% by mass or less; A thermoplastic resin (B1) having a melting point or lower of the thermoplastic resin (M) used as a material and urea or its derivative (C) are dried at a set temperature lower than the decomposition temperature of the urea or its derivative (C) and A step of stirring to obtain a mixture Step (ii): A thermoplastic resin (B2) that is not modified with a hydrophilic functional group and has a melting point equal to or lower than the melting point of the base material thermoplastic resin (M); Step of kneading the mixture obtained in step (i) at a set temperature equal to or lower than the decomposition temperature of the pulp fiber (A) Formula (a): 0 < (B2 mass) / {(A mass) x (100 - lignin amount) / 100} ≤ (B1 mass) / {(A mass) × (100-lignin content) / 100}
Formula (b): 0 < (B2 mass) / {(A mass) × (100-lignin content) / 100} ≤ (C mass) / {(A mass) × (100-lignin content) / 100}
(11) The method for producing a fiber-reinforced resin masterbatch according to (10), wherein the pulp fibers (A) further have a moisture content of 1% or more and 90% or less.
(12) A method for producing a resin composition, comprising the step of kneading the fiber-reinforced resin masterbatch produced by the production method according to (10) or (11) and the thermoplastic resin (M).

INDUSTRIAL APPLICABILITY According to the present invention, a fiber-reinforced resin masterbatch capable of obtaining a resin composition having a high tensile modulus and suppressing the occurrence of black spots due to cellulose-derived aggregates, and a resin composition using the same. can provide things. Also, a method for producing this fiber-reinforced resin masterbatch and a method for producing a resin composition can be provided.

The fiber-reinforced resin masterbatch of the present invention will be described below. In the present invention, "-" includes end values. That is, "X through Y" includes the values X and Y at both ends.

(Fiber-reinforced resin masterbatch)
The fiber-reinforced resin masterbatch (sometimes abbreviated as "masterbatch") of the present invention is a fiber-reinforced resin masterbatch for thermoplastic resin (M), and has a Canadian standard freeness of 0 mL or more and 600 mL. Hereinafter, pulp fibers (A) having a lignin content of 1% by mass or more and 30% by mass or less, and a thermoplastic resin (M) modified with a hydrophilic functional group and having a melting point equal to or lower than the melting point of the base material thermoplastic resin (M) A thermoplastic resin (B1), a thermoplastic resin (B2) that is not modified with a hydrophilic functional group and has a melting point equal to or lower than the melting point of the thermoplastic resin (M) serving as the base material, and urea or a derivative thereof ( C) and, and satisfy the following formulas (a) and (b) at the same time.
Formula (a): 0 < (B2 mass) / {(A mass) × (100-lignin content) / 100} ≤ (B1 mass) / {(A mass) × (100-lignin content) / 100}
Formula (b): 0 < (B2 mass) / {(A mass) × (100-lignin content) / 100} ≤ (C mass) / {(A mass) × (100-lignin content) / 100}

(Pulp fiber (A))
The pulp fiber (A) used in the present invention can be obtained by pulping a pulp raw material. The pulp raw material may be either wood or non-wood. Wood raw materials used for producing wood pulp include softwoods, hardwoods, and the like. Non-wood raw materials used to produce non-wood pulp include cotton, hemp, sisal, Manila hemp, flax, straw, bamboo, bagasse, kenaf, and the like. The pulp raw material (wood raw material, non-wood raw material) may be unbleached (before bleaching) or bleached (after bleaching).

The method of pulping the wood raw material is not particularly limited, and an example is a pulping method commonly used in the paper industry. Wood pulp can be classified according to the pulping method, for example, chemical pulp cooked by methods such as Kraft method, sulfite method, soda method, polysulfide method; ); semi-chemical pulp obtained by mechanical pulping after pretreatment with chemicals; waste paper pulp; deinked pulp, and the like.

The pulp fiber (A) contained in the masterbatch of the present invention has a Canadian standard freeness of 0 mL or more and 600 mL or less, preferably 30 mL or more and 300 mL or less, more preferably 50 mL or more and 250 mL or less. If the freeness exceeds 600 mL, the effect cannot be exhibited. The Canadian standard freeness of the pulp fiber (A) can be measured according to JIS P 8121-2:2012.

Pulp fibers (A) were mechanically treated from the viewpoint that uniform penetration and contact of urea with cellulose in the pulp fibers leads to an improvement in the final strength of the fiber-reinforced resin. is preferred. It is expected that the mechanical treatment increases the specific surface area of the pulp and increases the amount of urea reaction.

In the present invention, the mechanical treatment generally refers to mixing fibers in a dispersion medium represented by water and further pulverizing or fibrillating, and includes beating, fibrillation, dispersion, and the like. Refinement means that the fiber length, fiber diameter, etc. are reduced, and fibrillation means that the fiber becomes more fluffy. Apparatus used for mechanical treatment is not limited, but examples include apparatus of types such as high-speed rotary, colloid mill, high pressure, roll mill, and ultrasonic, high pressure or ultrahigh pressure homogenizer, refiner, beater, PFI. Mills, kneaders, dispersers, high-speed disaggregators, topfiners, etc., centering on a rotating shaft, can be used to make wet pulp work with a metal or blade and pulp fibers, or by friction between pulp fibers. In the present invention, the mechanical treatment is preferably beating using a refiner or a kneader because the fibrillation of fibers can be efficiently advanced, and a disc refiner or conical refiner capable of high-concentration treatment is used. Beating treatment is more preferable.

The mechanical treatment is carried out using a mixture containing the above pulp and a dispersion medium. More preferably, it is 18% by mass or more. (Mechanical treatment at this concentration is also referred to as “high-concentration mechanical treatment”.) The dispersion medium is not limited, and an organic solvent or water can be used, but water is preferred. Solids concentration is the concentration of solids in the mixture subjected to mechanical treatment. By subjecting the pulp to mechanical treatment such as beating under conditions of a high solid content concentration of 10% by mass or more, merits such as improved treatment efficiency and improved handling properties can be obtained. As handling properties, for example, after high-concentration mechanical treatment, it can be transported as it is at high concentration without dilution, and the viscosity of the pulp dispersion that has undergone high-concentration mechanical treatment is not high and can be pumped. Another advantage is that the dispersion is less likely to stick to the inside of the storage container. Furthermore, when the drying step is performed after the high-concentration mechanical treatment, the amount of volatilized dispersion medium is small and the drying efficiency is good. Furthermore, it is preferable to subject the pulp of the present invention to chemically modified pulp to high-concentration mechanical treatment because the viscosity of the dispersion is less likely to increase.

If the solid content concentration during mechanical treatment exceeds 50% by mass, drying proceeds in the apparatus during the treatment and scorching of the material is likely to occur. A condition of mass % or less is more preferable.

Further, the pulp fiber (A) has a lignin content of 1% by mass or more and 30% by mass or less, preferably 3% by mass or more and 25% by mass or less, and more preferably 5% by mass or more and 20% by mass or less. If the lignin content is too much more than the above upper limit, the reinforcing effect will be reduced because the proportion of reinforcing fibers will be relatively low. Affinity is lowered and interfacial strength between fiber and resin is lowered. The content of lignin can be adjusted by delignifying or bleaching the pulp raw material, which is the raw material of the pulp fiber (A). Moreover, the measurement of lignin content can be performed using the Clason method, for example.

In addition, the pulp fiber (A) used in the present invention preferably has a moisture content of 1 to 90%, more preferably 10 to 85%, and still more preferably 20 to 80%, from the viewpoint of preventing aggregation and handling. is. The moisture content can be measured using, for example, a moisture meter that measures heat loss.

The decomposition temperature of the pulp fiber (A) used in the present invention can be calculated from the 1% weight loss temperature when the pulp fiber is heated at 10° C./min in a nitrogen atmosphere.

The pulp fiber (A) used in the present invention may be used in an unmodified state, but may be chemically modified by acetylation, oxidation, esterification, etherification, or the like.

(acetylation modification)
In the acetylated modified pulp (sometimes simply referred to as “acetylated pulp”) that can be used in the present invention, the hydrogen atoms of the hydroxyl groups present on the surface of the pulp raw material cellulose are acetyl groups (CH ₃ —CO—). is replaced with Substitution with an acetyl group increases hydrophobicity and reduces aggregation during drying, thereby improving workability and facilitating dispersion and fibrillation in the resin after kneading. In addition, since highly reactive hydroxyl groups are substituted with acetyl groups, thermal decomposition of cellulose is suppressed and heat resistance during kneading is improved. The degree of acetyl group substitution (DS) of the acetylated pulp is preferably 0.4 to 1.3, more preferably 0.6 to 1.1, from the viewpoint of workability and maintaining the crystallinity of cellulose fibers. adjust.

(acetylation reaction)
The acetylation reaction is carried out by suspending the raw material in an anhydrous aprotic polar solvent capable of swelling the cellulose raw material, such as N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), adding acetic anhydride, acetyl chloride, It is possible to carry out the reaction in a short time by using an acetyl halide such as, for example, in the presence of a base. As the base used in this acetylation reaction, pyridine, N,N-dimethylaniline, sodium carbonate, sodium hydrogencarbonate, potassium carbonate, etc. are preferred, and potassium carbonate is more preferred. Also, by using an excess amount of an acetylation reagent such as acetic anhydride, the reaction can be carried out under conditions that do not use anhydrous aprotic polar solvents or bases.

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

(Washing)
The acetylated pulp obtained by the acetylation reaction is preferably subjected to washing treatment such as water replacement after the acetylation treatment.

(dehydration)
In the washing treatment, dehydration may be performed as necessary. As the dehydration method, a pressurized dehydration method using a screw press, a vacuum dehydration method using volatilization or the like can be used, 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 approximately 10 to 60%.

(dry)
The acetylated pulp that can be used in the present invention is subjected to a drying treatment after the dehydration step. The drying treatment can be performed, for example, by using a microwave dryer, a blow dryer or a vacuum dryer, but a drum dryer, a paddle dryer, a Nauta mixer, a batch dryer with stirring blades, etc., can be used. A dryer that can dry while drying is preferred. Drying is preferably carried out until the moisture content of the acetylated pulp reaches about 1 to 40%, more preferably 1 to 10%, even more preferably 1 to 5%. By using the dried pulp, it is possible to reduce the influence of hydrolysis of the pulp by water in the kneading step, which will be described later.

(Oxidation modification)
Oxidation can be carried out as known. Oxidation treatment improves handling during pulp densification during mechanical treatment. For example, there is a method of oxidizing raw pulp in water using an oxidizing agent in the presence of an N-oxyl compound and a substance selected from the group consisting of bromides, iodides and mixtures thereof. According to this method, the primary hydroxyl group at the C6 position of the glucopyranose ring on the cellulose surface is selectively oxidized to generate a group selected from the group consisting of an aldehyde group, a carboxyl group and a carboxylate group. Alternatively, an ozone oxidation method may be mentioned. According to this oxidation reaction, at least the hydroxyl groups at the 2nd and 6th positions of the glucopyranose rings constituting cellulose are oxidized, and the cellulose chain is decomposed.

An example of the method for measuring the amount of carboxyl groups is described below. Prepare 60 mL of a 0.5% by mass slurry (aqueous dispersion) of oxidized cellulose, add 0.1 M hydrochloric acid aqueous solution to adjust the pH to 2.5, and then drop 0.05 N sodium hydroxide aqueous solution to adjust the pH to 11. Measure the electrical conductivity until the It can be calculated using the following formula from the amount (a) of sodium hydroxide consumed in the neutralization stage of the weak acid whose electrical conductivity changes slowly.
Carboxyl group amount [mmol/g oxidized cellulose] = a [mL] x 0.05/oxidized cellulose mass [g]

The amount of carboxyl groups in the oxidized cellulose measured in this way is preferably 0.1 mmol/g or more, more preferably 0.3 mmol/g or more, still more preferably 0.5 mmol/g, relative to the absolute dry mass. 0.8 mmol/g or more, more preferably 0.8 mmol/g or more. The upper limit of the amount is preferably 3.0 mmol/g or less, more preferably 2.5 mmol/g or less, still more preferably 2.0 mmol/g or less. Therefore, the amount is preferably 0.1 to 3.0 mmol/g, more preferably 0.3 to 2.5 mmol/g, still more preferably 0.5 to 2.5 mmol/g, and 0.8 to 2.0 mmol /g is even more preferred.

(Etherification and esterification)
As etherification and esterification, modification can be performed by known methods such as carboxymethylation, phosphate esterification, phosphite esterification, and sulfate esterification.

(Carboxymethylation modification)
Carboxymethylation can be carried out as known. Carboxymethylation treatment improves handling during pulp densification during mechanical treatment. The degree of carboxymethyl substitution per glucose unit of carboxymethylated cellulose is measured, for example, by the following method. That is, 1) About 2.0 g of carboxymethylated cellulose (absolute dry) is precisely weighed and placed in a 300 mL Erlenmeyer flask with a common stopper. 2) Add 100 mL of methanol nitrate (100 mL of special grade concentrated nitric acid added to 1000 mL of methanol) and shake for 3 hours to convert carboxymethyl cellulose salt (carboxymethyl cellulose) into hydrogen carboxymethyl cellulose. 3) About 1.5 g to 2.0 g of hydrogen-form carboxymethylated cellulose (absolute dry) is accurately weighed and placed in a 300 mL conical flask with a common stopper. 4) Wet hydrogen carboxymethyl cellulose with 15 mL of 80% methanol, add 100 mL of 0.1N NaOH, and shake at room temperature for 3 hours. ₅ ) Back _- titrate excess NaOH with 0.1N H2SO4 using phenolphthalein as indicator. 6) Calculate the degree of carboxymethyl substitution (DS) by the formula:
A = [(100 × F'-(0.1 N H ₂ SO ₄ ) (mL) × F) × 0.1]/(absolute dry weight of hydrogen-form carboxymethylated cellulose (g))
DS = 0.162 x A/(1 - 0.058 x A)
A: Amount of 1N NaOH (mL) required to neutralize 1 g of hydrogen-type carboxymethylated cellulose
F: Factor of _{0.1N H2SO4} F': Factor of 0.1N NaOH

The degree of carboxymethyl substitution per anhydroglucose unit in the carboxymethylated cellulose is preferably 0.01 or more, more preferably 0.05 or more, and even more preferably 0.10 or more. The upper limit of the degree of substitution is preferably 0.50 or less, more preferably 0.40 or less, and even more preferably 0.35 or less. Therefore, the degree of carboxymethyl group substitution is preferably 0.01 to 0.50, more preferably 0.05 to 0.40, even more preferably 0.10 to 0.35.

(Thermoplastic resin (B1))
The thermoplastic resin (B1) used in the present invention must be modified with a hydrophilic functional group, preferably acid-modified. The term "hydrophilicity" as used herein means having good affinity with water and the surface of cellulose. Hydrophilic functional groups include hydroxyl, carboxy, carbonyl, amino, amide, and sulfo groups. Examples of such thermoplastic resins (B1) include base-modified polyolefins and acid-modified polyolefins, and among them, maleic anhydride-modified polypropylene (MAPP) and maleic anhydride-modified polyethylene (MAPE) are exemplified.

The melting point of the thermoplastic resin (B1) used in the present invention is not higher than the melting point of the thermoplastic resin (M) described below from the viewpoint of easy dispersibility. Here, for example, the melting point of maleic anhydride-modified polypropylene (MAPP) is 150°C, and the melting point of maleic anhydride-modified polyethylene (MAPE) is 120°C. In addition, the melting point of the thermoplastic resin (B1) is the thermal decomposition temperature of urea or its derivative (C) described later (simply It is sometimes abbreviated as “decomposition temperature”). When urea is used as (C), the thermal decomposition temperature of urea is 135°C.

The thermoplastic resin (B1) functions as a compatibilizing resin. The compatibilizing resin functions to uniformly mix the cellulose fibers with different hydrophobicities and the thermoplastic resin (M) to be described later, and to improve adhesion. For example, in the case of maleic anhydride-modified polyolefin, factors that determine the characteristics of the compatibilizing resin include the amount of dicarboxylic acid added and the weight-average molecular weight of the polyolefin resin serving as the base material. A polyolefin resin having a large amount of dicarboxylic acid added increases compatibility with a hydrophilic polymer such as cellulose, but the molecular weight of the resin decreases during the addition process, resulting in a decrease in the strength of the molded product. As an optimum balance, the amount of dicarboxylic acid added is 20-100 mgKOH/g, more preferably 45-65 mgKOH/g. If the amount added is small, the number of points that interact with the hydroxyl groups of cellulose and the hydroxyl groups and modified functional groups contained in modified cellulose in the resin decreases. Further, when the addition amount is large, self-aggregation due to hydrogen bonding between carboxyl groups in the resin, or reduction in the molecular weight of the base material olefin resin due to excessive addition reaction, the strength as a reinforced resin is not achieved. 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 rises significantly during melting, resulting in poor workability during kneading and molding defects.

The content of the thermoplastic resin (B1) is preferably 10 to 70% by mass, more preferably 20 to 50% by mass, based on the mass (100% by mass) of the pulp fibers (A) excluding lignin. If the amount added exceeds 70% by mass, the amount exceeds the amount necessary for forming an interface between the cellulose and the resin.

The thermoplastic resin (B1) may be used singly or as a mixed resin of two or more. In the case of use as a graft of one or more polymers and polyolefin, the polyolefin resin constituting the graft is not particularly limited. can be used.

(Thermoplastic resin (B2))
The thermoplastic resin (B2) used in the present invention is not modified with a hydrophilic functional group, and its melting point is lower than the melting point of the thermoplastic resin (M), which will be described later, from the viewpoint of easy dispersibility. Although the lower limit is not particularly limited, it is preferably 60.degree.

Examples of the thermoplastic resin (B2) include homopolypropylene (hPP, melting point: 165°C), high-density polyethylene (HDPE, melting point: 132°C), low-density polyethylene (LDPE, melting point: 95-135°C), linear Examples include polyolefins such as low-density polyethylene (LLDPE, melting point: 124° C.) and block copolymers such as block polypropylene (bPP, melting point: 160-165° C.).

The blending amount of the thermoplastic resin (B2) is 1 to 50% by mass is preferred, and 5 to 40% by mass is more preferred. In addition, the amount of the thermoplastic resin (B2) blended is not more than the amount of the thermoplastic resin (B1) blended so as not to inhibit the formation of the interface. In addition, the blending amount of the thermoplastic resin (B2) is equal to or less than the blending amount of urea or its derivative (C), which will be described later, so as not to inhibit the denaturation of cellulose.

(Urea or its derivative (C))
In the present invention, from the viewpoint of improving the strength of the resulting resin composition, urea or its derivative (C) (hereinafter sometimes abbreviated as "urea, etc.") is used as a low-molecular-weight auxiliary agent that imparts a primary amine. ) is used. Examples of urea derivatives include thiourea, biuret, phenylurea, benzylurea, dimethylurea, tetramethylurea, and compounds in which hydrogen atoms of urea are substituted with alkyl groups. These can be used individually or in combination. However, it is preferred to use urea.

Urea has a thermal decomposition temperature of 135°C, and when the temperature exceeds 135°C, it decomposes into ammonia and isocyanic acid. It is believed that the unmodified hydroxyl groups react with the generated isocyanic acid to promote the formation of urethane bonds, and it is speculated that the hydrophobicity increases compared to cellulose fibers not subjected to urea treatment. Furthermore, by melt-kneading simultaneously with the thermoplastic resin (B1) having an acid anhydride, the amino group newly introduced on the surface of the cellulose fiber by the urea treatment and the carboxylic acid of the thermoplastic resin (B1) become hydrophilic mutual. It is believed that this action enables the formation of a stronger composite of the cellulose fibers and the thermoplastic resin (B1).

The blending amount of urea and its derivative (C) is the mass of pulp fiber (A) excluding lignin from the viewpoint of suppressing the decrease in strength due to aggregation of fibers due to too much blending amount of (C). is preferably less than 0.8, more preferably 0.05 or more and less than 0.75, even more preferably 0.1 or more and less than 0.7. The ratio of the mass of urea and its derivative (C) to the solid content mass of the pulp fiber (A) excluding lignin can be represented by the following formula (c).
Formula (c): (C mass) / {(A mass) × (100-lignin content) / 100}
Here, the amount of lignin in the above formula is obtained from the mass% of lignin in the pulp fiber (A). For example, the amount of lignin in pulp fiber (A) containing 10% by mass of lignin is 10. (The same shall apply hereinafter).

(Fiber-reinforced resin masterbatch)
The fiber-reinforced resin masterbatch of the present invention contains pulp fibers (A), a thermoplastic resin (B1), a thermoplastic resin (B2), urea or a derivative thereof (C), and has the following formula (a) and formula ( b) is satisfied at the same time. In addition, the A mass in the following formulas (a) and (b) indicates the solid content mass of the pulp fiber (A).
Formula (a): 0 < (B2 mass) / {(A mass) × (100-lignin content) / 100} ≤ (B1 mass) / {(A mass) × (100-lignin content) / 100}
Formula (b): 0 < (B2 mass) / {(A mass) × (100-lignin content) / 100} ≤ (C mass) / {(A mass) × (100-lignin content) / 100}
The formula (a) above indicates that the mass of the thermoplastic resin (B2) contained in the masterbatch is greater than 0 and equal to or less than the mass of the thermoplastic resin (B1).
The above formula (b) indicates that the mass of the thermoplastic resin (B2) contained in the masterbatch is greater than 0 and equal to or less than the mass of urea or its derivative (C).

(Manufacturing method of fiber-reinforced resin masterbatch)
The method for producing the fiber-reinforced resin masterbatch of the present invention is not particularly limited, but for example, it can be produced by performing the following steps (i) and (ii).

(Step (i))
In step (i), pulp fibers (A), thermoplastic resin (B1), and urea or its derivative (C) are dried and stirred at a temperature below the decomposition temperature of urea or its derivative (C), get a mixture.

In the step (i), as a device for drying and stirring the pulp fiber (A), the thermoplastic resin (B1), and urea or its derivative (C), the dryer includes a microwave dryer and a blower dryer. It can be done using a machine or a vacuum dryer, but mixers such as Henschel mixers and super mixers whose rotating shaft stands vertically and can be dried while dispersing with stirring blades, and Roedige mixers whose rotating shaft is horizontal Mixers capable of drying while dispersing with blades, single-screw or multi-screw kneaders (extruders), drum dryers, paddle dryers, Nauta mixers, batch-type dryers, etc. can be done.

(Step (ii))
In step (ii), the thermoplastic resin (B2) and the mixture obtained in step (i) are kneaded at a set temperature below the decomposition temperature of the pulp fibers (A) to produce a masterbatch.

As a device for performing kneading in step (ii) of the present invention, it is preferable to use a single-screw or multi-screw kneader (extruder). In addition to being able to melt-knead the pulp fiber (A) with the thermoplastic resin (B1) and the thermoplastic resin (B2), a twin-screw kneader (extrusion It is desirable to have a multi-screw kneader (extruder) such as a kneader (machine), a four-screw kneader (extruder), and a plurality of kneaders, rotors, etc. in the parts constituting the screw.

The method for producing a fiber-reinforced resin masterbatch of the present invention may include a step of washing the masterbatch with water after step (ii). The temperature of water used for washing is preferably room temperature to 100°C, more preferably 50 to 100°C. After washing, it is preferable to dry until the moisture content reaches about 0.1 to 5% from the viewpoint of preventing decomposition of the thermoplastic resin (M) used as the base material and reducing the drying load during kneading.

(resin composition)
The resin composition of the present invention is obtained by kneading the above fiber-reinforced resin masterbatch and a thermoplastic resin (M) as a base material. In this specification, the thermoplastic resin (M) is sometimes called a diluent resin.

(Thermoplastic resin (M))
As the thermoplastic resin (M) used in the present invention, the following common thermoplastic resins having a melting temperature of 250° C. or less can be mentioned. The thermoplastic resin (M) may be used singly or as a mixture of two or more resins.

General thermoplastic resins include polyolefin resin, polyamide resin, polyvinyl chloride, polystyrene, polyvinylidene chloride, fluororesin, (meth)acrylic resin, polyester, polylactic acid, copolymer resin of lactic acid and ester, poly Glycolic acid, acrylonitrile-butadiene-styrene copolymer (ABS resin), polyphenylene oxide, polyurethane, polyacetal, vinyl ether resin, polysulfone resin, cellulose resin (triacetylated cellulose, diacetylated cellulose, etc.), etc. can be used. can.

As the polyolefin resin, polyethylene, polypropylene (hereinafter also referred to as "PP"), ethylene-propylene copolymer, polyisobutylene, polyisoprene, polybutadiene, etc. can be used.

Polyamide resin (PA) is also expected to interact with hydroxyl groups of cellulose that have not been affected by urea, and can be preferably used. PA includes 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 610 (nylon 610, PA610), polyamide 612 (nylon 612, PA612), etc., aromatic diamines such as phenylenediamine, aromatic dicarboxylic acids such as terephthaloyl chloride and isophthaloyl chloride, or aromatic PAs composed of derivatives thereof etc. can be mentioned. From the viewpoint of high affinity with cellulose fibers and cellulose nanofibers, it is preferable to use aliphatic PA, more preferably PA6, PA11, and PA12, and particularly preferably PA6. Moreover, a polyamide resin may be used individually by 1 type, and may be used in mixture of 2 or more types of polyamide resins.

The resins exemplified above can be used not only as homopolymers but also as block copolymers containing less than half of resins having various known functions.

(Method for producing resin composition)
A resin composition is obtained by kneading the fiber-reinforced resin masterbatch and the thermoplastic resin (M) as the base material.

When the thermoplastic resin (M) is added and melt-kneaded, the masterbatch and the thermoplastic resin (M) may be mixed without heating at room temperature and then melt-kneaded, or may be mixed with heating. It may be melt-kneaded.

As an apparatus for adding the thermoplastic resin (M) and performing melt-kneading, the same apparatus as used in the step (ii) of the above-described masterbatch production method can be used. Moreover, the heating setting temperature during melt-kneading is preferably about ±10° C., the minimum processing temperature recommended by the thermoplastic resin supplier for the thermoplastic resin (M). By setting the temperature within this temperature range, the pulp and 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, glue and casein; tannins, zeolites, ceramics, metal powders, etc. colorants; plasticizers; fragrances; pigments; flow control agents; leveling agents; conductive agents; may The content of any additive may be appropriately contained within a range that does not impair the effects of the present invention.

INDUSTRIAL APPLICABILITY According to the present invention, a fiber-reinforced resin masterbatch capable of obtaining a resin composition having a high tensile modulus and suppressing the occurrence of black spots due to cellulose-derived aggregates, and a resin composition using the same. can provide things. Also, a method for producing this fiber-reinforced resin masterbatch and a method for producing a resin composition can be provided.

(Application)
Molding materials and molded articles (molding materials and molded articles) can be produced using the resin composition of the present invention. Examples of the shape of the molded body include various shaped bodies such as film-like, sheet-like, plate-like, pellet-like, powder-like, and three-dimensional structures. As a molding method, die molding, injection molding, extrusion molding, blow molding, foam molding, etc. can be used.

The molded article (molded article) can be used not only in the field of fiber-reinforced plastics where matrix moldings (molded articles) containing cellulose fibers are used, but also in fields requiring thermoplasticity and mechanical strength (tensile strength, etc.).

Interior materials, exterior materials, structural materials, etc. for transportation equipment such as automobiles, trains, ships, and airplanes; housings, structural materials, internal parts, etc. for electrical appliances such as personal computers, televisions, telephones, and clocks; mobile communications such as mobile phones Housings, structural materials, internal parts, etc. of equipment; housings, structural materials, internal parts, etc. of portable music players, video players, printers, copiers, sporting goods; building materials; office equipment such as stationery, etc. It can be effectively used as a vessel, container, or the like.

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these.

(Measurement of Canadian Standard Freeness (CSF))
The Canadian standard freeness of pulp fibers used in Examples and Comparative Examples was measured according to JIS P 8121-2:2012.

(Measurement of Lignin Content) The lignin content of the pulp fibers used in Examples and Comparative Examples was measured according to the Clarson method, which is commonly used as a quantitative method (Clarson lignin). The lignin content can also be derived based on the kappa number measured according to JIS P 8211:2011. Since the relationship between the lignin content and the kappa number generally changes for each type of pulp, it is necessary to derive the correlation with the above-mentioned Clarson lignin. For example, in the case of softwood kraft pulp, the lignin content = kappa number × 0 It can also be derived in .15. In addition, in this specification, when the lignin content is 10% by mass, the lignin content is 10.

(Measurement of tensile modulus)
150 g of pellet-shaped resin moldings obtained in Examples and Comparative Examples were put into a small molding machine ("MC15" manufactured by Xplore Instruments), and the heating cylinder temperature was 200 ° C. and the mold temperature was 40 ° C. A dumbbell-shaped test piece (type A12, JIS K 7139) was molded. The tensile modulus of the obtained test piece was measured using a precision universal testing machine ("Autograph AG-Xplus" manufactured by Shimadzu Corporation) at a test speed of 1 mm/min and an initial distance between gauge lines of 30 mm. A dumbbell-shaped test piece was molded in the same manner as described above using only the diluent resin (hPP), and the tensile modulus of the obtained test piece was measured in the same manner as described above. Table 1 shows the results of the ratio of the measured values of each sample at each time as the reinforcement rate.

(Evaluation of the presence or absence of aggregates in the resin composition)
60 mg of the pellet-shaped resin moldings obtained in Examples and Comparative Examples were pressed using a compression molding machine manufactured by Shindo Kinzoku Kogyo Co., Ltd. at 200 ° C. to 2.5 MPa, resulting in a diameter of about 35 mm × thickness A film with a thickness of 0.1 mm was produced. This film was visually checked, and the case where black spots were visible was judged as "presence of aggregates", and the case where black spots were not visible was judged as "absence" of aggregates. Table 1 shows the results.

(Materials used for manufacturing masterbatch and resin composition)
(A) Pulp fiber (decomposition temperature: 299°C)
(B1) Thermoplastic resin Maleic anhydride-modified polypropylene (MAPP): (Toyo Tac PMA-H1000P manufactured by Toyobo Co., Ltd.: amount of dicarboxylic acid added 57 mg KOH / g, melting point: 150 ° C.)
(B2) Thermoplastic resin Homopolypropylene (hPP): (PP MA04A manufactured by Japan Polypropylene Corporation, melting point: 165°C)
・Block polypropylene (bPP): (J-466HP manufactured by Prime Polymer Co., Ltd., melting point: 160 to 165 ° C.)
・ High density polyethylene (HDPE): (HJ360 manufactured by Japan Polyethylene Co., Ltd., melting point: 132 ° C.)
・Low density polyethylene (LDPE): (ULT-ZEX 20200J manufactured by Prime Polymer Co., Ltd., melting point: 95 to 135 ° C.)
- Linear low-density polyethylene (LLDPE): (Suntech LD M6520 manufactured by Asahi Kasei Corporation, melting point: 124 ° C.)
(C) Urea: (powder: manufactured by Wako Pure Chemical Industries)
(M) Resin for dilution Homopolypropylene (hPP): (PP MA04A manufactured by Japan Polypropylene Corporation, melting point: 165°C)

(Production example 1)
(Production of pulp fiber 1)
Softwood unbleached kraft pulp (NUKP) with a solid content concentration of 18% by mass is processed with a single disc refiner (manufactured by Kumagai Riki Kogyo Co., Ltd., plate blade width: 4 mm, groove width: 5 mm) until the Canadian standard freeness (CSF) reaches 222 mL. ), the beating treatment was performed three times under the condition of a clearance of 0.25 mm to obtain pulp fibers 1 having a moisture content of 20%. The lignin content of the pulp fiber 1 was 7.9% by mass.

(Production example 2)
(Production of Pulp Fiber 2)
Softwood unbleached kraft pulp (NUKP) with a solid content concentration of 18% by mass is processed with a single disc refiner (manufactured by Kumagai Riki Kogyo Co., Ltd., plate blade width: 4 mm, groove width: 5 mm) until the Canadian standard freeness (CSF) reaches 128 mL. ), the beating treatment was performed four times under the condition of a clearance of 0.25 mm to obtain pulp fibers 2 having a moisture content of 20%. The lignin content of the pulp fiber 2 was 9.1% by mass.

(Example 1)
(Manufacturing of masterbatch)
391 g of solid content of pulp fiber 1 produced in Production Example 1, 108 g of MAPP, and 36 g of urea were dried and stirred under conditions of 130° C. or less using a twin-screw extruder to obtain a mixture. The whole amount of this mixture and 36 g of HDPE were kneaded using a twin-screw extruder at 180° C. or less to obtain a masterbatch.

(Manufacture of resin composition)
32 g of the obtained masterbatch and 168 g of diluent resin (hPP) were mixed and kneaded under heating conditions of 180° C. or less using a twin-screw extruder. The melt-kneaded product was then pelletized using a pelletizer to obtain a pellet-like resin composition (molded article) containing pulp fiber 1, MAPP, a urea-derived compound, HDPE, and diluent resin (hPP).

(Example 2)
A masterbatch was produced in the same manner as in Example 1, except that the amount of urea used in the production of the masterbatch was 108 g. 36 g of the obtained masterbatch and 164 g of diluent resin (hPP) were mixed and kneaded under heating conditions of 180° C. or less using a twin-screw extruder. The melt-kneaded product was then pelletized using a pelletizer to obtain a pellet-like resin composition (molded article) containing pulp fiber 1, MAPP, a urea-derived compound, HDPE, and diluent resin (hPP).

(Example 3)
A masterbatch was produced in the same manner as in Example 1, except that the amount of urea used in the production of the masterbatch was 108 g, and the amount of HDPE used was 108 g. 40 g of the obtained masterbatch and 160 g of diluent resin (hPP) were mixed and kneaded under heating conditions of 180° C. or less using a twin-screw extruder. The melt-kneaded product was then pelletized using a pelletizer to obtain a pellet-like resin composition (molded article) containing pulp fiber 1, MAPP, a urea-derived compound, HDPE, and diluent resin (hPP).

(Example 4)
(Manufacturing of masterbatch)
396 g of solid content of pulp fiber 2 produced in Production Example 2, 108 g of MAPP, and 252 g of urea were dried and stirred at 130° C. or lower using a twin-screw extruder to obtain a mixture. The whole amount of this mixture and 108 g of HDPE were kneaded using a twin-screw extruder at 180° C. or less to obtain a masterbatch.

(Manufacture of resin composition)
48 g of the obtained masterbatch and 152 g of diluent resin (hPP) were mixed and kneaded under heating conditions of 180° C. or less using a twin-screw extruder. The melt-kneaded product was then pelletized using a pelletizer to obtain a pellet-like resin composition (molded article) containing pulp fiber 2, MAPP, a urea-derived compound, HDPE, and diluent resin (hPP).

(Example 5)
A masterbatch and a resin composition (molding) were produced in the same manner as in Example 1, except that LDPE was used instead of HDPE.

(Example 6)
A masterbatch and a resin composition (molded article) were produced in the same manner as in Example 2, except that LDPE was used instead of HDPE.

(Example 7)
A masterbatch and a resin composition (molded body) were produced in the same manner as in Example 1, except that LLDPE was used instead of HDPE.

(Example 8)
A masterbatch and a resin composition (molding) were produced in the same manner as in Example 2, except that LLDPE was used instead of HDPE.

(Example 9)
A masterbatch and a resin composition (molded article) were produced in the same manner as in Example 4, except that hPP was used instead of HDPE.

(Example 10)
A masterbatch and a resin composition (molding) were produced in the same manner as in Example 4, except that bPP was used instead of HDPE.

(Comparative example 1)
A masterbatch was produced in the same manner as in Example 1, except that the amount of HDPE used in the production of the masterbatch was 108 g. 36 g of the obtained masterbatch and 164 g of diluent resin (hPP) were mixed and kneaded under heating conditions of 180° C. or less using a twin-screw extruder. The melt-kneaded product was then pelletized using a pelletizer to obtain a pellet-like resin composition (molded article) containing pulp fiber 1, MAPP, a urea-derived compound, HDPE, and diluent resin (hPP).

(Comparative example 2)
A masterbatch was produced in the same manner as in Example 4, except that HDPE was not used. 42 g of the obtained masterbatch and 158 g of diluent resin (hPP) were mixed and kneaded under heating conditions of 180° C. or less using a twin-screw extruder. The melt-kneaded product was then pelletized using a pelletizer to obtain a pellet-like resin composition (molded article) containing pulp fiber 2, MAPP, a urea-derived compound, and a diluent resin (hPP).

As can be seen from Examples 1 to 10 in Table 1, a pulp fiber (A) having a Canadian standard freeness of 0 mL or more and 600 mL or less and a lignin content of 1% by mass or more and 30% by mass or less, and modified with a hydrophilic functional group A thermoplastic resin (B1) having a melting point equal to or lower than the melting point of the thermoplastic resin (M) serving as the base material, and a thermoplastic resin (B1) not modified with a hydrophilic functional group and having a melting point of the base material thermoplastic resin (B1) A fiber-reinforced resin masterbatch that contains a thermoplastic resin (B2) having a melting point of the resin (M) or lower and urea or a derivative thereof (C) and simultaneously satisfies the following formulas (a) and (b): When used, the resin composition obtained by diluting and kneading this with the thermoplastic resin (M) has an excellent tensile modulus, and the film produced from this resin composition has no black spots and cellulose. There were no clumps of origin.
Formula (a): 0 < (B2 mass) / {(A mass) × (100-lignin content) / 100} ≤ (B1 mass) / {(A mass) × (100-lignin content) / 100}
Formula (b): 0 < (B2 mass) / {(A mass) × (100-lignin content) / 100} ≤ (C mass) / {(A mass) × (100-lignin content) / 100}
On the other hand, in Comparative Example 1, the amount of urea added is less than the amount of the thermoplastic resin (B2) added, does not satisfy the formula (b), and compared with the resin composition using the masterbatch of Examples 1 to 10, It was inferior in tensile modulus.
Moreover, Comparative Example 2 does not contain the thermoplastic resin (B2), and the film produced from the resin composition using this masterbatch was confirmed to have black spots. That is, it was found that cellulose-derived aggregates were present.

Claims (12)

A fiber-reinforced resin masterbatch for a thermoplastic resin (M),
Pulp fibers (A) having a Canadian standard freeness of 0 mL or more and 600 mL or less and a lignin content of 1% by mass or more and 30% by mass or less;
a thermoplastic resin (B1) modified with a hydrophilic functional group and having a melting point equal to or lower than the melting point of the thermoplastic resin (M) serving as the base material;
a thermoplastic resin (B2) that is not modified with a hydrophilic functional group and has a melting point equal to or lower than the melting point of the thermoplastic resin (M) serving as the base material;
A fiber-reinforced resin masterbatch containing urea or a derivative thereof (C) and simultaneously satisfying the following formulas (a) and (b).
Formula (a): 0 < (B2 mass) / {(A mass) × (100-lignin content) / 100} ≤ (B1 mass) / {(A mass) × (100-lignin content) / 100}
Formula (b): 0 < (B2 mass) / {(A mass) × (100-lignin content) / 100} ≤ (C mass) / {(A mass) × (100-lignin content) / 100} The fiber-reinforced resin masterbatch according to claim 1, further satisfying the following formula (c).
Formula (c): (C mass) / {(A mass) × (100-lignin content) / 100} <0.8 The fiber-reinforced resin masterbatch according to claim 1 or 2, wherein the pulp fibers (A) further have a water content of 1% or more and 90% or less. The fiber-reinforced resin masterbatch according to any one of claims 1 to 3, wherein the modification of the thermoplastic resin (B1) is acid modification. The fiber-reinforced resin masterbatch according to any one of claims 1 to 4, wherein at least one of the thermoplastic resin (B1) and the thermoplastic resin (B2) is a block copolymer. The fiber-reinforced resin masterbatch according to any one of claims 1 to 5, wherein at least one of the thermoplastic resin (B1) and the thermoplastic resin (B2) is polyolefin. The fiber-reinforced resin masterbatch according to any one of claims 1 to 6, wherein the thermoplastic resin (B1) is acid-modified polyolefin and the thermoplastic resin (B2) is polyethylene. The fiber-reinforced resin masterbatch according to any one of claims 1 to 7, wherein the thermoplastic resin (M) is polyolefin. A resin composition obtained by kneading the fiber-reinforced resin masterbatch according to any one of claims 1 to 8 and the thermoplastic resin (M). A method for producing a fiber-reinforced resin masterbatch for a thermoplastic resin (M), comprising the following steps (i) and (ii), and the obtained fiber-reinforced resin masterbatch is represented by the following formula (a) and formula ( A method for producing a fiber-reinforced resin masterbatch that satisfies b) at the same time.
Step (i):
Pulp fibers (A) having a Canadian standard freeness of 0 mL or more and 600 mL or less and a lignin content of 1% by mass or more and 30% by mass or less;
a thermoplastic resin (B1) modified with a hydrophilic functional group and having a melting point equal to or lower than the melting point of the thermoplastic resin (M) serving as the base material;
Urea or a derivative thereof (C),
Step (ii):
a thermoplastic resin (B2) that is not modified with a hydrophilic functional group and has a melting point equal to or lower than the melting point of the thermoplastic resin (M) serving as the base material;
the mixture obtained in the step (i),
Step of kneading at a set temperature below the decomposition temperature of the pulp fiber (A) Formula (a): 0 < (B2 mass) / {(A mass) × (100-lignin content) / 100} ≤ (B1 mass) / {(A mass) × (100-lignin content) / 100}
Formula (b): 0 < (B2 mass) / {(A mass) × (100-lignin content) / 100} ≤ (C mass) / {(A mass) × (100-lignin content) / 100} 11. The method for producing a fiber-reinforced resin masterbatch according to claim 10, wherein the pulp fibers (A) further have a moisture content of 1% or more and 90% or less. A method for producing a resin composition, comprising kneading a fiber-reinforced resin master batch produced by the production method according to claim 10 or 11 and the thermoplastic resin (M).