JP7236841B2 - Fibrous cellulose composite resin and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fibrous cellulose composite resin and a method for producing the same.

In recent years, various proposals have been made to use cellulose nanofibers (CNF) as reinforcing materials for resins. However, cellulose nanofibers irreversibly aggregate due to intermolecular hydrogen bonds derived from hydroxyl groups of polysaccharides. Therefore, even if the cellulose nanofibers are used as a resin reinforcing material, the reinforcing effect of the resin cannot be sufficiently exhibited due to the poor dispersibility of the cellulose nanofibers in the resin.

Therefore, for example, Patent Document 1 proposes a polyolefin resin composition characterized by containing a terpene phenol-based compound as a compatibilizer for a resin mixture composed of cellulose nanofibers having an average thickness of 10 to 200 nm and a polyolefin resin. are doing. The same document states that the dispersibility of cellulose nanofibers is improved when terpene phenol is included (see, for example, paragraph 0038). However, the dispersibility of cellulose nanofibers is sufficiently improved even when terpene phenol is included. There is room for doubt as to whether or not terpene phenol can be used as a compatibilizing agent.

Further, for example, Patent Document 2 proposes a method of obtaining cellulose fine fibers by esterifying cellulose with a base catalyst or an acid catalyst and a dibasic carboxylic acid anhydride. The document states that the introduction of a fluorene compound into the obtained cellulose fine fibers can improve the compatibility with organic media such as resins. However, the method of the document uses a base catalyst or an acid catalyst, and the reaction conditions are severe, resulting in the problem of coloration of the cellulose fibers.

JP 2016-79311 A JP-A-2017-82188

A main problem to be solved by the present invention is to provide a fibrous cellulose composite resin which is excellent in strength, particularly in bending elastic modulus, and free from coloring problems, and a method for producing the same.

In order to solve the above problems, the present inventors performed various treatments on cellulose nanofibers and searched for a kneading method of cellulose nanofibers and resin. In other words, various studies were conducted on the premise of using cellulose nanofibers. However, even if the cellulose nanofibers are hydrophobically modified, the dispersibility in the resin is not sufficient, and it is difficult to form a three-dimensional network of the cellulose nanofibers in the resin, resulting in a sufficient reinforcing effect of the resin. I couldn't.

However, in the course of the research, when the raw material fiber is microfiber cellulose, the dispersibility in the resin is good, the three-dimensional network of the microfiber cellulose is formed in the resin, and the resin has a sufficient reinforcing effect. I found that I could get On the premise of this, we have further improved the dispersibility of fibrous cellulose, thereby improving the strength of the resin, and in addition, we have come up with a fibrous cellulose composite resin in which the problem of coloration is solved, and a method for producing the same. rice field. Specifically, it is the means shown below.

(Means according to claim 1)
Microfiber cellulose and resin with an average fiber width of 0.1 μm or more, and polybasic acid salts,
The polybasic acid salt is at least one of phthalates and phthalate derivatives ,
The phthalates are at least one selected from potassium hydrogen phthalate, sodium hydrogen phthalate, sodium phthalate, and ammonium phthalate.
A fibrous cellulose composite resin characterized by:

(Means according to claim 2)
The microfiber cellulose has an average fiber length of 0.02 to 3.0 mm and a fibrillation rate of 1.0 to 30%.
The fibrous cellulose composite resin according to claim 1.

(Means according to claim 3 )
a portion of the polybasic acid salts have modified the microfiber cellulose;
The fibrous cellulose composite resin according to claim 1 or 2 .

(Means according to claim 4 )
Microfiber cellulose is obtained by fibrillating raw material fibers in a range where the average fiber width is 0.1 μm or more,
Kneading the microfiber cellulose and resin, and polybasic acid salts,
The polybasic acid salt is at least one of phthalates and phthalate derivatives ,
The phthalates are at least one selected from potassium hydrogen phthalate, sodium hydrogen phthalate, sodium phthalate, and ammonium phthalate.
A method for producing a fibrous cellulose composite resin, characterized by:

INDUSTRIAL APPLICABILITY According to the present invention, a fibrous cellulose composite resin that is excellent in strength, particularly in bending elastic modulus, and free from coloring problems, and a method for producing the same are provided.

Next, a mode for carrying out the invention will be described. Note that this embodiment is an example of the present invention. The scope of the present invention is not limited to the scope of this embodiment.

The fibrous cellulose composite resin of the present embodiment contains microfiber cellulose having an average fiber width of 0.1 μm or more, a resin, and polybasic acid salts. In addition, in obtaining this fibrous cellulose composite resin, the raw material fibers are fibrillated to form microfiber cellulose having an average fiber width of 0.1 μm or more, and this microfiber cellulose, resin, and polybasic acid salts are kneaded, A fibrous cellulose composite resin containing the polybasic acid salt is obtained. They will be explained in order below.

(Raw material fiber)
Microfiber cellulose (MFC) can be obtained by subjecting raw material fibers (pulp fibers) to a refining (fibrillation) treatment. As the raw material fibers, one or more of plant-derived fibers, animal-derived fibers, microorganism-derived fibers, and the like can be selected and used. However, it is preferable to use pulp fibers, which are vegetable fibers. If the raw material fiber is pulp fiber, it is inexpensive and can avoid the problem of thermal recycling.

Plant-derived fibers include 1 from wood pulp made from broad-leaved trees, conifers, etc., non-wood pulp made from straw, bagasse, etc., and waste paper pulp (DIP) made from recycled waste paper, waste paper, etc. A species or two or more species can be selected and used.

As the wood pulp, one or more of chemical pulps such as hardwood kraft pulp (LKP) and softwood kraft pulp (NKP), mechanical pulp (TMP), and waste paper pulp (DIP) are selected and used. can be done. These pulps are pulps used in papermaking applications, and by using these pulps, existing equipment can be effectively utilized.

The hardwood kraft pulp (LKP) may be bleached hardwood kraft pulp, unbleached hardwood kraft pulp, or semi-bleached hardwood kraft pulp. Similarly, softwood kraft pulp (NKP) may be softwood bleached kraft pulp, softwood unbleached kraft pulp, or softwood semi-bleached kraft pulp.

The waste paper pulp (DIP) may be magazine waste paper pulp (MDIP), newspaper waste paper pulp (NDIP), corrugated waste paper pulp (WP), or other waste paper pulp. good.

Furthermore, as mechanical pulp, for example, stone ground pulp (SGP), pressure stone ground pulp (PGW), refiner ground pulp (RGP), chemi ground pulp (CGP), thermo ground pulp (TGP), ground pulp (GP ), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), refiner mechanical pulp (RMP), bleached thermomechanical pulp (BTMP), and the like. .

(Pretreatment step)
The raw fibers are preferably pretreated by chemical means. Pretreatment by a chemical method prior to the refining (fibrillation) treatment can significantly reduce the number of refining treatments and significantly reduce the energy required for the refining treatment.

Pretreatments by chemical methods include hydrolysis of polysaccharides by acid (acid treatment), hydrolysis of polysaccharides by enzymes (enzyme treatment), swelling of polysaccharides by alkali (alkali treatment), and oxidation of polysaccharides by oxidants (oxidation treatment). ), reduction of polysaccharides with a reducing agent (reduction treatment), and the like.

By performing alkali treatment prior to the refining process, some of the hydroxyl groups of the hemicellulose and cellulose that the pulp possesses are dissociated, and the molecules are anionized, weakening the intramolecular and intermolecular hydrogen bonds. It has the effect of promoting the dispersion of

Examples of alkalis include organic alkalis such as sodium hydroxide, lithium hydroxide, potassium hydroxide, aqueous ammonia solution, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, and benzyltrimethylammonium hydroxide. However, it is preferable to use sodium hydroxide from the viewpoint of manufacturing cost.

If enzymatic treatment, acid treatment, or oxidation treatment is performed prior to pulverization treatment, the water retention of the microfiber cellulose can be lowered, the degree of crystallinity can be increased, and the homogeneity can be enhanced. In this regard, it is thought that the lower the water retention of the microfiber cellulose, the better the dispersibility in the resin, and the higher the homogeneity of the microfiber cellulose, the less defects that cause the resin composition to break. It is considered that a composite resin having a large strength capable of holding the is obtained. In addition, enzymatic treatment, acid treatment, and oxidation treatment decompose the hemicellulose and amorphous regions of cellulose in the pulp. As a result, the energy required for the refining process can be reduced, and the homogeneity and dispersibility of the fibers can be improved. be able to. In addition, when the ratio of the cellulose crystal region, which is considered to be rigid and low in water retention due to the alignment of the molecular chains, to the entire fiber increases, the dispersibility improves and the aspect ratio decreases, but the ductility is maintained. A composite resin having high mechanical strength can be obtained.

Among the various treatments described above, it is preferable to perform enzyme treatment, and in addition, it is more preferable to perform one or more treatments selected from acid treatment, alkali treatment, and oxidation treatment. The alkali treatment will be described in detail below.

As a method of alkali treatment, for example, there is a method of immersing raw fibers in an alkali solution.

The alkaline compound contained in the alkaline solution may be an inorganic alkaline compound or an organic alkaline compound.

Examples of inorganic alkali compounds include hydroxides of alkali metals or alkaline earth metals, carbonates of alkali metals or alkaline earth metals, phosphate salts of alkali metals or alkaline earth metals, and the like. Examples of alkali metal hydroxides include lithium hydroxide, sodium hydroxide, potassium hydroxide, and the like. Examples of hydroxides of alkaline earth metals include calcium hydroxide. Examples of alkali metal carbonates include lithium carbonate, lithium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate, sodium carbonate, sodium hydrogen carbonate, and the like. Examples of carbonates of alkaline earth metals include calcium carbonate. Examples of alkali metal phosphates include lithium phosphate, potassium phosphate, trisodium phosphate, and disodium hydrogen phosphate. Examples of alkaline earth metal phosphates include calcium phosphate and calcium hydrogen phosphate.

Examples of organic alkali compounds include ammonia, aliphatic amines, aromatic amines, aliphatic ammoniums, aromatic ammoniums, heterocyclic compounds and their hydroxides, carbonates and phosphates. Specifically, for example, ammonia, hydrazine, methylamine, ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, butylamine, diaminoethane, diaminopropane, diaminobutane, diaminopentane, diaminohexane, cyclohexylamine, aniline , tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, pyridine, N,N-dimethyl-4-aminopyridine, ammonium carbonate, ammonium hydrogen carbonate, Diammonium hydrogen phosphate and the like can be exemplified.

The solvent of the alkaline solution may be either water or an organic solvent, preferably a polar solvent (water, a polar organic solvent such as alcohol), more preferably an aqueous solvent containing at least water.

The pH of the alkaline solution at 25° C. is preferably 9 or higher, more preferably 10 or higher, and particularly preferably 11-14. If the pH is 9 or more, the yield of MFC will be high. However, if the pH exceeds 14, the handleability of the alkaline solution deteriorates.

(Refinement (defibration) process)
For example, a beater, a high-pressure homogenizer, a homogenizer such as a high-pressure homogenizer, a grinder, a millstone friction machine such as a grinder, a single-screw kneader, a multi-screw kneader, a kneader refiner, etc. are used to refine the raw material fibers. can be performed by beating, preferably using a refiner.

A refiner is a device for beating pulp fibers, and a known device can be used. As the refiner, a conical type, a double disc refiner (DDR), and a single disc refiner (SDR) are preferable because they can efficiently impart a shearing force to pulp fibers and advance preliminary fibrillation. . In addition, it is preferable to use a refiner in the fibrillation treatment step because it eliminates the need for separation and washing after the treatment.

Microfiber cellulose is a fiber made of cellulose or a derivative of cellulose. Ordinary microfiber cellulose has a strong hydration property and stably maintains a dispersed state (dispersion state) by being hydrated in an aqueous medium. The single fibers that constitute the microfiber cellulose may sometimes form a fibrous form in which multiple strands are aggregated in an aqueous medium.

The refining (defibration) treatment is preferably carried out in a range in which the number average fiber diameter (fiber width, average diameter of single fibers) of the microfiber cellulose is 0.1 μm or more, and is in the range of 0.1 to 15 μm. It is more preferable to carry out in the range of 0.1 to 9 μm, and it is particularly preferable to carry out in the range. By carrying out the number average fiber diameter (width) in a range of 0.1 μm or more, the dispersibility of the cellulose fibers is improved, and the strength of the fibrous cellulose composite resin is improved.

Specifically, if the average fiber diameter is less than 0.1 μm, it is no different from cellulose nanofibers, and a sufficient reinforcing effect (especially bending elastic modulus) cannot be obtained. In addition, the time required for the miniaturization process is long, and a large amount of energy is required, leading to an increase in manufacturing costs. On the other hand, when the average fiber diameter exceeds 15 μm, the dispersibility of the fibers tends to be poor. If the dispersibility of the fibers is insufficient, the reinforcing effect tends to be poor. Furthermore, if the average fiber diameter is less than 0.1 μm, the viscosity becomes too high when the fibrous cellulose is mixed with the polybasic acid salt in the state of aqueous dispersion, and it is necessary to stir at a high shear, which consumes energy. disadvantageous in terms of Moreover, stirring at a high shear may cause the fibrous cellulose to be torn apart, deteriorated, or the like.

The average fiber length (length of single fiber) of microfiber cellulose is preferably 0.02 to 3.0 mm, more preferably 0.05 to 2.0 mm, and 0.1 to 1.5 mm. is particularly preferred. If the average fiber length is less than 0.02 mm, a three-dimensional network cannot be formed between the fibers, and there is a risk that the reinforcing effect will be significantly reduced. The average fiber length can be arbitrarily adjusted by, for example, selection of raw material fibers, pretreatment, and fibrillation treatment.

The fibrillation rate of the microfiber cellulose is preferably 1.0% or more, more preferably 1.5% or more, and particularly preferably 2.0% or more. Also, the fibrillation rate of the microfiber cellulose is preferably 30.0% or less, more preferably 20.0% or less, and particularly preferably 15.0% or less.

If the fibrillation rate exceeds 30.0%, the fineness progresses too much to form nanofibers, so there is a possibility that the intended effect cannot be obtained. On the other hand, if the fibrillation rate exceeds 30%, when the fibrous cellulose is mixed with the polybasic acid salt in the form of an aqueous dispersion, the viscosity becomes too high and it may become difficult to uniformly stir the fibrous cellulose. . In spite of this, if the mixture is stirred forcibly, the fibrous cellulose may be torn apart, deteriorated, or the like.

On the other hand, if the fibrillation rate is less than 1.0%, there are few hydrogen bonds between fibrils, resulting in a lack of a strong three-dimensional network. In this regard, the present inventors have found in various tests that when the fibrillation rate of the microfiber cellulose is 1.0% or more, the fibrils of the microfiber cellulose are hydrogen-bonded to each other to construct a stronger three-dimensional network. found in the process.

As for the fiber length of the microfiber cellulose, the ratio of 0.2 mm or less is preferably 12% or more, more preferably 16% or more, and particularly preferably 26% or more. If the ratio is less than 12%, a sufficient reinforcing effect may not be obtained.

The fiber length of the microfiber cellulose does not have an upper limit of 0.2 mm or less, and may be all 0.2 mm or less.

The aspect ratio of the microfiber cellulose is preferably 2 to 5,000, more preferably 100 to 1,000, in order to improve the mechanical strength while maintaining some ductility of the resin.

The aspect ratio is the value obtained by dividing the average fiber length by the average fiber width. It is thought that the greater the aspect ratio, the greater the number of locations in the resin where catching occurs, thus increasing the reinforcing effect, but on the other hand, the greater the catching, the less the ductility of the resin. There is knowledge that when an inorganic filler is kneaded with a resin, the larger the aspect ratio of the filler is, the higher the bending strength is, but the elongation is significantly reduced.

The crystallinity of the microfibrous cellulose is preferably 50% or higher, more preferably 55% or higher, particularly preferably 60% or higher. If the degree of crystallinity is less than 50%, the compatibility with the resin is improved, but the strength of the fiber itself is lowered, so the effect of reinforcing the resin composition tends to be poor.

On the other hand, the crystallinity of the microfibrous cellulose is preferably 90% or less, more preferably 88% or less, and especially preferably 86% or less. If the degree of crystallinity exceeds 90%, the ratio of strong hydrogen bonds in the molecule increases and the fiber itself becomes rigid, but the compatibility with the resin decreases, and the reinforcing effect of the resin composition tends to be inferior.

The degree of crystallinity can be arbitrarily adjusted by, for example, selection of raw material fibers, pretreatment, and refinement treatment.

The pulp viscosity of the microfiber cellulose is preferably 2 cps or greater, more preferably 4 cps or greater. If the pulp viscosity is less than 2 cps, aggregation of the microfiber cellulose cannot be sufficiently suppressed when the microfiber cellulose is kneaded with the resin, and the reinforcement effect of the resin composition tends to be inferior.

The freeness of the microfiber cellulose is preferably 500cc or less, more preferably 300cc or less, and particularly preferably 100cc or less. If it exceeds 500 cc, the fiber width of the microfiber cellulose exceeds 15 μm, and the reinforcing effect is not sufficient.

(kneading)
The microfiber cellulose obtained by the pulverization treatment can be once dispersed in an aqueous medium to form a dispersion. It is particularly preferable that the entire amount of the aqueous medium is water, but it is also possible to preferably use an aqueous medium that is partly another liquid that is compatible with water. Other liquids that can be used include lower alcohols having 3 or less carbon atoms.

The solid content concentration of the dispersion is preferably 1.0% by mass or more, more preferably 1.5% by mass or more, and particularly preferably 2.0% by mass or more. The solid content concentration of the dispersion is preferably 70% by mass or less, more preferably 60% by mass or less, and particularly preferably 50% by mass or less.

Microfiber cellulose may be dehydrated and dried prior to kneading with resin or the like. In other words, the dehydration/drying treatment and the kneading treatment of the microfiber cellulose may not be performed at the same time, and the microfiber cellulose may be dried at the same time as the kneading. Moreover, the dehydration treatment and the drying treatment may be performed together or separately.

For the dehydration treatment, for example, one or more selected from belt press, screw press, filter press, twin roll, twin wire former, valveless filter, center disk filter, membrane treatment, centrifugal separator, etc. can be used.

Drying treatments include, for example, rotary kiln drying, disk drying, airflow drying, medium fluidized drying, spray drying, drum drying, screw conveyor drying, paddle drying, single-screw kneading drying, multi-screw kneading drying, vacuum drying, and stirring drying. 1 type or 2 or more types can be selected and used from among.

A pulverization process may be added after the dehydration/drying process. For the pulverization treatment, for example, one or more of bead mills, kneaders, dispersers, twist mills, cut mills, hammer mills and the like can be selected and used.

The dehydrated and dried microfiber cellulose can be in the form of powder, pellet, sheet, or the like. However, powder form is preferred.

When powdered, the average particle size of the microfiber cellulose is preferably 1 to 10,000 μm, more preferably 10 to 5,000 μm, particularly preferably 100 to 1,000 μm. If the average particle size exceeds 10,000 μm, the particles may not enter the kneading device due to the large particle size. On the other hand, if the average particle size is less than 1 μm, energy is required for pulverization, which is not economical.

When powdered, the bulk specific gravity of the microfiber cellulose is preferably 0.01 to 1.5, more preferably 0.04 to 1, and particularly preferably 0.1 to 0.5. A bulk specific gravity exceeding 1.5 means that the specific gravity of cellulose exceeds 1.5, which is physically difficult to achieve. On the other hand, setting the bulk specific gravity to less than 0.01 is disadvantageous in terms of transportation costs.

The moisture content (moisture content) of the dehydrated and dried microfiber cellulose is preferably 0.1% or more, more preferably 1.0% or more, and particularly preferably 10.0% or more. If the moisture content of the microfiber cellulose to be kneaded with the polybasic acid salt is 0.1% or more, the denaturation of the cellulose fiber by the polybasic acid salt does not proceed, and the resulting composite resin contains the polybasic acid salt. Become.

The dehydrated and dried microfiber cellulose may contain a resin. When the resin is contained, the hydrogen bonding between the dehydrated and dried microfiber cellulose is inhibited, and the dispersibility in the resin during kneading can be improved.

Examples of the form of the resin contained in the dehydrated and dried microfiber cellulose include powder, pellet, and sheet. However, the powder form (powder resin) is preferable.

When powdered, the average particle size of the resin powder contained in the dehydrated and dried microfiber cellulose is preferably 1 to 10,000 μm, more preferably 10 to 5,000 μm, and particularly preferably 100 to 1,000 μm. If the average particle size exceeds 10,000 μm, the particles may not enter the kneading device due to the large particle size. On the other hand, when the average particle size is less than 1 μm, there is a possibility that hydrogen bonding between microfiber celluloses cannot be inhibited due to fineness. The resin such as the powdered resin used here may be of the same type or different from the resin to be kneaded with the microfiber cellulose (the resin as the main raw material), but is preferably of the same type.

The resin powder having an average particle size of 1 to 10,000 μm is preferably mixed in an aqueous dispersion state before dehydration and drying. By mixing in an aqueous dispersion state, the resin powder can be uniformly dispersed between the microfiber celluloses, and the microfiber cellulose can be uniformly dispersed in the composite resin after kneading, further improving the strength properties. be able to.

The microfiber cellulose thus obtained is kneaded with a resin to form a kneaded product. During this kneading, a polybasic acid salt is added. As described above, the moisture content of the microfiber cellulose is important during kneading.

As the resin, either a thermoplastic resin or a thermosetting resin can be used.

Examples of thermoplastic resins include polyolefins such as polypropylene (PP) and polyethylene (PE), polyester resins such as aliphatic polyester resins and aromatic polyester resins, polyacrylic resins such as polystyrene, methacrylates and acrylates, polyamide resins, One or more of polycarbonate resins, polyacetal resins and the like can be selected and used.

However, it is preferable to use at least one of polyolefin and polyester resin. Polypropylene is preferably used as the polyolefin.

As polypropylene, one or more of homopolymers, random polymers, and block polymers can be selected and used. Furthermore, as polyester resins, aliphatic polyester resins such as polylactic acid and polycaprolactone can be exemplified, and aromatic polyester resins such as polyethylene terephthalate can be exemplified. It is preferable to use a polyester resin having

As the biodegradable resin, for example, one or more of hydroxycarboxylic acid-based aliphatic polyesters, caprolactone-based aliphatic polyesters, dibasic acid polyesters, and the like can be selected and used.

Hydroxycarboxylic acid-based aliphatic polyesters include, for example, homopolymers of hydroxycarboxylic acids such as lactic acid, malic acid, glucose acid, and 3-hydroxybutyric acid, and copolymers using at least one of these hydroxycarboxylic acids. One or two or more may be selected and used from among polymers and the like. However, it is preferable to use polylactic acid, a copolymer of lactic acid and the above hydroxycarboxylic acids other than lactic acid, polycaprolactone, and a copolymer of at least one of the above hydroxycarboxylic acids and caprolactone. It is particularly preferred to use

As the lactic acid, for example, L-lactic acid, D-lactic acid, or the like can be used, and these lactic acids may be used alone or two or more of them may be selected and used.

As the caprolactone-based aliphatic polyester, for example, one or more of polycaprolactone homopolymers and copolymers of polycaprolactone and the above hydroxycarboxylic acids can be selected and used. .

As the dibasic acid polyester, for example, one or more of polybutylene succinate, polyethylene succinate, polybutylene adipate and the like can be selected and used.

A biodegradable resin may be used individually by 1 type, or may use 2 or more types together.

Examples of thermosetting resins include phenol resins, urea resins, melamine resins, furan resins, unsaturated polyesters, diallyl phthalate resins, vinyl ester resins, epoxy resins, urethane resins, silicone resins, thermosetting polyimide resins, and the like. can be used. These resins can be used alone or in combination of two or more.

The resin may contain an inorganic filler, preferably in a proportion that does not interfere with thermal recycling.

Examples of inorganic fillers include simple substances of metal elements in groups I to VIII of the periodic table such as Fe, Na, K, Cu, Mg, Ca, Zn, Ba, Al, Ti, and silicon elements; substances, hydroxides, carbonates, sulfates, silicates, sulfites, various clay minerals composed of these compounds, and the like.

Specifically, for example, barium sulfate, calcium sulfate, magnesium sulfate, sodium sulfate, calcium sulfite, zinc oxide, silica, heavy calcium carbonate, light calcium carbonate, aluminum borate, alumina, iron oxide, calcium titanate, hydroxide Examples include aluminum, magnesium hydroxide, calcium hydroxide, sodium hydroxide, magnesium carbonate, calcium silicate, clay wollastonite, glass beads, glass powder, silica sand, silica stone, quartz powder, diatomaceous earth, white carbon, and glass fiber. be able to. A plurality of these inorganic fillers may be contained. It may also be contained in waste paper pulp.

The mixing ratio of the microfiber cellulose and the resin is preferably 0.1 to 100 parts by mass, more preferably 1 to 80 parts by mass, more preferably 5 to 60 parts by mass, based on 100 parts by mass of the resin. Parts by mass are particularly preferred. However, when the blending ratio of the microfiber cellulose is 0.1 to 100 parts by mass, the strength of the composite resin, particularly the bending strength and tensile modulus strength, can be remarkably improved.

In addition, the content ratio of the microfiber cellulose and the resin contained in the finally obtained composite resin is usually the same as the above mixing ratio of the microfiber cellulose and the resin.

(Polybasic acid salts)
Polybasic salts include, for example, oxalates, malonates, succinates, glutarates, adipates, tartrates, glutamates, sebacates, hexafluorosilicates, maleates, itacones Acid salts, citraconates, citrates, phthalates, derivatives of phthalates, and the like can be used. When polybasic acid salts are used, coloring of the obtained resin composition is suppressed, and foaming at high temperatures is suppressed, as compared with the case of using polybasic acids. In addition, polybasic acid salts have fewer hydrogen ions in carboxyl groups than polybasic acids, so it is thought that acid decomposition of cellulose fibers is suppressed, thereby suppressing coloration. Polybasic acids are more likely to volatilize and foam at higher temperatures than polybasic acid salts.

However, as polybasic acid salts, it is preferable to use at least one of phthalates and derivatives of phthalates. The flexural modulus of the resulting resin composition is improved by using phthalates and derivatives thereof.

In this case, the phthalates are preferably at least one selected from potassium hydrogen phthalate, sodium hydrogen phthalate, sodium phthalate, and ammonium phthalate.

This form is not primarily aimed at modifying microfiber cellulose (substituting some of the hydroxyl groups with specific functional groups) using polybasic salts. In this embodiment, the polybasic acid salt is used as a compatibilizing agent, thereby (improving compatibility) to improve the strength and the like of the obtained composite resin. In this respect, the quality of the resulting composite resin is stabilized unless the cellulose fibers are modified.

However, in this embodiment, part of the polybasic acid salts may be configured to modify the microfiber cellulose. In the case of modifying cellulose fibers with polybasic salts, some of the hydroxyl groups are substituted with predetermined functional groups, improving compatibility between the microfiber cellulose and the resin.

Modification of the microfiber cellulose is preferably carried out so that some of the hydroxyl groups of the cellulose constituting the fiber are substituted with functional groups represented by the following structural formulas.

構造式中のＲは、直鎖状、分枝鎖状、若しくは環状の飽和炭化水素基又はその誘導基；直鎖状、分枝鎖状、若しくは環状の不飽和炭化水素基又はその誘導基；芳香族基又はその誘導基；のいずれかである。また、αは有機物又は無機物からなる１価以上の陽イオンである。

R in the structural formula is a linear, branched, or cyclic saturated hydrocarbon group or derivative thereof; a linear, branched, or cyclic unsaturated hydrocarbon group or derivative thereof; an aromatic group or a derivative thereof; α is a monovalent or higher cation composed of an organic substance or an inorganic substance.

For the kneading treatment, for example, one or more selected from single-screw or multi-screw kneaders with two or more screws, mixing rolls, kneaders, roll mills, Banbury mixers, screw presses, dispersers, etc. are used. be able to. Among them, it is preferable to use a multi-screw kneader with two or more screws. One or more multi-screw kneaders with two or more screws may be used in parallel or in series.

The temperature of the kneading treatment is higher than the glass transition point of the resin, and varies depending on the type of resin, but is preferably 80 to 280°C, more preferably 90 to 260°C, and more preferably 100 to 240°C. is particularly preferred.

The mixing ratio of polybasic acid salts to 100 parts by mass of microfiber cellulose is preferably 0.1 to 1,000 parts by mass, more preferably 1 to 500 parts by mass, and 10 to 200 parts by mass. is particularly preferred. If the mixing ratio of the polybasic acid salt is less than 0.1 parts by mass, a sufficient reinforcing effect cannot be obtained. On the other hand, when the blending ratio of the polybasic acid salt exceeds 1,000 parts by mass, the reinforcing effect reaches a plateau.

It is also suitable to add maleic anhydride modified polypropylene (MAPP) in mixing the microfiber cellulose and resin. Addition of the maleic anhydride-modified polypropylene improves the strength, particularly the bending strength, of the resulting resin composition.

The amount of maleic anhydride-modified polypropylene added is preferably 0.1 to 1,000 parts by mass, more preferably 1 to 500 parts by mass, more preferably 10 to 200 parts by mass, based on 100 parts by mass of microfiber cellulose. Parts by mass are particularly preferred. If the amount of maleic anhydride-modified polypropylene added is less than 0.1 part by mass, the strength is not sufficiently improved. On the other hand, if the amount of the maleic anhydride-modified polypropylene added exceeds 1,000 parts by mass, it becomes excessive and the strength tends to decrease.

(Other compositions)
Microfibrous cellulose includes one or more of various fine fibers called cellulose nanofiber, microfibril cellulose, microfibrillar fine fiber, microfiber cellulose, microfibrillated cellulose, super microfibril cellulose, and the like. can be included, and these fine fibers may also be included. In addition, it is also possible to include, or may include, fibers obtained by further miniaturizing these fine fibers. However, it is necessary that the proportion of microfiber cellulose in all raw material fibers is 10% by mass or more, preferably 30% by mass or more, and more preferably 60% by mass or more.

In addition to the above, kenaf, jute hemp, manila hemp, sisal hemp, ganpi, mitsumata, mulberry, banana, pineapple, coconut palm, corn, sugar cane, bagasse, palm, papyrus, reed, esparto, sabaigrass, barley, rice, bamboo, Fibers derived from plant materials obtained from various plants such as various coniferous trees (such as cedar and cypress), broad-leaved trees, and cotton can also be included, and may be included.

Raw materials for fibrous cellulose composite resins include microfiber cellulose, resins and polybasic salts, as well as additives such as antistatic agents, flame retardants, antibacterial agents, coloring agents, radical scavengers, and foaming agents. 1 or 2 or more can be selected from and used as long as the effects of the present invention are not impaired.

These raw materials may be kneaded at the time of kneading the microfiber cellulose dispersion, the microfiber cellulose and the resin, kneaded with these kneaded products, or kneaded by other methods. However, from the viewpoint of production efficiency, it is preferable to knead the microfiber cellulose and the resin at the same time.

(Molding process)
The microfiber cellulose and the resin (kneaded product) are preferably kneaded again, if necessary, and then molded into a desired shape. Although microfiber cellulose is dispersed in the kneaded product, the kneaded product is excellent in moldability.

The size, thickness, shape, and the like of the molded product are not particularly limited, and may be, for example, sheet-like, pellet-like, powder-like, fibrous-like, or the like.

The temperature during the molding process is equal to or higher than the glass transition point of the resin, and varies depending on the type of resin, but is preferably 80 to 280°C, more preferably 90 to 260°C, and more preferably 100 to 240°C. is particularly preferred.

As the apparatus for molding treatment, for example, one or more of injection molding machines, blow molding machines, blow molding machines, blow molding machines, compression molding machines, extrusion molding machines, vacuum molding machines, air pressure molding machines, etc. can be selected and used.

The molding treatment can be performed by a known molding method, such as die molding, injection molding, extrusion molding, blow molding, foam molding, and the like. Alternatively, the kneaded product may be spun into a fibrous form and mixed with the above-described plant material or the like to form a mat or board. Mixing can be carried out, for example, by a method of simultaneous deposition by air laying.

This molding process may be carried out after the kneading process, or the kneaded material may be cooled once, chipped using a crusher or the like, and then the chips may be placed in a molding machine such as an extruder or an injection molding machine. You can also put it in.

(Definition of terms, measurement method, etc.)
Unless otherwise specified, the terms used in the specification are as follows.

(average fiber diameter)
100 ml of an aqueous dispersion of microfiber cellulose with a solid content concentration of 0.01 to 0.1% by mass is filtered through a Teflon (registered trademark) membrane filter, and the solvent is replaced once with 100 ml of ethanol and 3 times with 20 ml of t-butanol. . It is then freeze-dried and coated with osmium to form a sample. This sample is observed with an electron microscope SEM image at a magnification of 5,000, 10,000 or 30,000 times depending on the width of the constituent fibers. Specifically, two diagonal lines are drawn on the observation image, and three straight lines passing through the intersections of the diagonal lines are arbitrarily drawn. Furthermore, the width of a total of 100 fibers intersecting with these three straight lines is visually measured. Then, the median diameter of the measured value is taken as the average fiber diameter.

(average fiber length)
The length of each fiber is visually measured in the same manner as for the average fiber diameter. Let the median length of the measured value be the average fiber length.

(fiber analysis)
The proportion of fibers having a fiber length of 0.2 mm or less and the fibrillation rate are measured by a fiber analyzer "FS5" manufactured by Valmet.

(aspect ratio)
It is a value obtained by dividing the average fiber length by the average fiber width (diameter).

(crystallinity)
It is a value measured by an X-ray diffraction method in accordance with JIS-K0131 (1996) "General Rules for X-ray Diffraction Analysis". It should be noted that the microfiber cellulose has an amorphous portion and a crystalline portion, and the degree of crystallinity means the proportion of the crystalline portion in the entire microfiber cellulose.

(pulp viscosity)
Measure according to JIS-P8215 (1998). It should be noted that the higher the pulp viscosity, the higher the degree of polymerization of the microfiber cellulose.

(Freeness)
It is a value measured according to JIS P8121-2:2012.

(Moisture content (moisture content))
The moisture content of the fiber is a value calculated by the following formula, using a constant temperature dryer, holding the sample at 105° C. for 6 hours or more, and using the mass after drying as the mass when no change in mass is observed.
Fiber moisture content (%) = [(mass before drying - mass after drying) / mass before drying] x 100

Next, examples of the present invention will be described.
7 g of sodium phthalate and 83 g of polypropylene powder were added to 365 g of an aqueous dispersion of microfiber cellulose having a solid concentration of 2.75% by weight, and the mixture was dried by heating at 105° C. to obtain a fine cellulose fiber mixture. The moisture content of the microfiber cellulose mixture was less than 10%.

Next, the resulting fine cellulose fiber mixture was kneaded with a twin-screw kneader at 180° C. and 200 rpm to obtain a microfiber cellulose composite resin. This microfiber cellulose composite resin was cut with a pelleter into cylinders with a diameter of 2 mm and a length of 2 mm, and injection molded at 180° C. into cuboid specimens (length 59 mm, width 9.6 mm, thickness 3.8 mm). This test was performed multiple times while changing the types and mixing ratios of various mixed materials. Details are shown in Table 1.

The resulting test pieces were examined for flexural modulus and coloration, and the results are shown in Table 1. In addition, the bending elastic modulus and the evaluation method of coloring are as follows.

(bending test)
Measured according to JIS K7171:2008. The following criteria are used in the table.
○: When the bending elastic modulus of the resin itself is 1 and the bending elastic modulus (magnification) of the composite resin is 1.4 times or more ×: When the bending elastic modulus of the resin itself is 1, the bending elastic modulus (magnification) of the composite resin is 1 .When less than 4 times

(coloring)
○: Visually white to beige ×: Visually dark brown to black

INDUSTRIAL APPLICABILITY The present invention can be used as a fibrous cellulose composite resin and a method for producing the same.

Claims (4)

Microfiber cellulose and resin with an average fiber width of 0.1 μm or more, and polybasic acid salts,
The polybasic acid salt is at least one of phthalates and phthalate derivatives ,
The phthalates are at least one selected from potassium hydrogen phthalate, sodium hydrogen phthalate, sodium phthalate, and ammonium phthalate.
A fibrous cellulose composite resin characterized by: The microfiber cellulose has an average fiber length of 0.02 to 3.0 mm and a fibrillation rate of 1.0 to 30%.
The fibrous cellulose composite resin according to claim 1. a portion of the polybasic acid salts have modified the microfiber cellulose;
The fibrous cellulose composite resin according to claim 1 or 2 . Microfiber cellulose is obtained by fibrillating raw material fibers in a range where the average fiber width is 0.1 μm or more,
Kneading the microfiber cellulose and resin, and polybasic acid salts,
The polybasic acid salt is at least one of phthalates and phthalate derivatives ,
The phthalates are at least one selected from potassium hydrogen phthalate, sodium hydrogen phthalate, sodium phthalate, and ammonium phthalate.
A method for producing a fibrous cellulose composite resin, characterized by: