JP6968845B2 - Fibrous cellulose composite resin and its manufacturing method, and resin reinforcement - Google Patents

Description

The present invention relates to a fibrous cellulose composite resin, a method for producing the same, and a reinforcing material for the resin.

Cellulose nanofibers are usually obtained in the state of a dispersion (slurry), but transportation in the state of a dispersion increases the cost. Therefore, when commercializing it, it is rational to dry the dispersion of cellulose nanofibers and transport it as a dried product. However, when the dispersion is dried, the cellulose nanofibers are strongly aggregated by hydrogen bonds. Therefore, it is difficult to disperse the cellulose nanofibers in water again, and the cellulose nanofibers do not disperse as they did before drying.

Against this background, the present inventors have proposed the use of hydroxy acids for the purpose of improving the redispersibility of cellulose nanofibers (see Patent Document 1), and glycerin or a glycerin derivative. Proposed use (see Patent Document 2). According to these proposals, the redispersibility of cellulose nanofibers is sufficiently improved.

On the other hand, in recent years, fine fibers such as cellulose nanofibers and microfibrillated cellulose have been in the limelight for their use as reinforcing materials for resins. Therefore, the present inventors conducted various tests on the fine fibers made into a dried product according to the above proposal in order to investigate the performance as a reinforcing material for the resin. However, in the process of this test, it was found that there is room for improvement in the strength of the obtained fibrous cellulose composite resin when the dried product according to the above proposal is used.

Japanese Unexamined Patent Publication No. 2017-2138 JP-A-2017-101184

A main problem to be solved by the present invention is to provide a fibrous cellulose composite resin having excellent strength, a method for producing the same, and a resin reinforcing material having an excellent resin reinforcing effect even if it is made into a dried product.

Through various tests, the present inventors have found that the dried products of Patent Documents 1 and 2 are excellent in redispersibility in water, but inferior in dispersibility in resin. This contributed to the fact that the strength of the resin did not improve as expected even when a dried product (cellulose nanofiber, microfibrillated cellulose, etc.) was mixed with the resin. In this respect, it is possible to once disperse the dried product in water and mix it with the resin in the state of a dispersion liquid, but it is very inefficient to evaporate the water content such as cellulose nanofibers with the mixing with the resin. .. The means shown below have led to the idea of this background.

(Means according to claim 1)
Contains a mixture of fibrous cellulose and dispersant, and a resin.
The fibrous cellulose contains fibers having an average fiber diameter of 15 μm or less as a part or all of the fibrous cellulose.
The dispersant was selected from among melamine, urea phosphorylated starch, carbamic acid starch, lecithin, and casein having at least one functional group selected from hydroxyl groups, carboxy groups, and amine groups. At least one or more ,
The mixture is a heat-dried pulverized product having a bulk specific gravity of 0.03 to 1.0 and an average particle size of 1 to 1000 μm measured according to JIS K7365.
A fibrous cellulose composite resin characterized by this.

(Means according to claim 2)
The blending ratio of the fibrous cellulose and the fibrous cellulose in the resin is 10 to 50% by mass.
The fibrous cellulose composite resin according to claim 1.

(Means according to claim 3)
The water content of the mixture is 50% or less.
The fibrous cellulose composite resin according to claim 1 or 2.

(Means according to claim 4)
The fibrous cellulose is a fiber having an average fiber diameter of 100 nm or less.
The fibrous cellulose composite resin according to any one of claims 1 to 3.
(Means according to claim 5)
The mixing amount of the dispersant is 1 to 40 parts by mass with respect to 100 parts by mass of the fiber having an average fiber diameter of 100 nm or less.
The fibrous cellulose composite resin according to claim 4.

(Means according to claim 6)
A dispersant is mixed with the slurry of fibrous cellulose to form a mixture, and the mixture is dried and pulverized to form a powder, which is then kneaded with the resin.
Fibers having an average fiber diameter of 15 μm or less are used as part or all of the fibrous cellulose.
The dispersant was selected from melamine, urea phosphorylated starch, carbamic acid starch, lecithin, and casein having at least one functional group selected from hydroxyl groups, carboxy groups, and amine groups. At least one or more ,
The drying is carried out by heating and drying so that the bulk specific gravity of the mixture measured according to JIS K7365 is 0.03 to 1.0 and the average particle size is 1 to 1000 μm.
A method for producing a fibrous cellulose composite resin.
(Means according to claim 7)
The heat drying includes rotary kiln drying, disk drying, air flow drying, medium flow drying, spray drying, drum drying, screw conveyor drying, paddle drying, uniaxial kneading drying, multiaxial kneading drying, vacuum drying, and stirring drying. Select and use one or more of the above,
The method for producing a fibrous cellulose composite resin according to claim 6.

(Means according to claim 8)
As the fibrous cellulose, fibers having an average fiber diameter of 100 nm or less are used, and the fibers are used.
The mixing amount of the dispersant is 1 to 40 parts by mass with respect to 100 parts by mass of the fiber having an average fiber diameter of 100 nm or less.
The method for producing a fibrous cellulose composite resin according to claim 6 or 7.

(Means according to claim 9)
It is a reinforcing material for thermoplastic resin or thermosetting resin.
A mixture of fibrous cellulose and a dispersant,
The fibrous cellulose contains fibers having an average fiber diameter of 15 μm or less as a part or all of the fibrous cellulose.
The dispersing agent is a hydroxyl group, it is selected melamine to have at least any one or more functional groups selected from among carboxyl groups and amine groups, urea phosphorylated starch, carbamic acid starch, lecithin, and from casein At least one of them ,
It is a heat-dried pulverized product having a bulk specific gravity of 0.03 to 1.0 and an average particle size of 1 to 1000 μm measured according to JIS K7365.
A resin reinforcement that is characterized by this.

According to the present invention, it is a fibrous cellulose composite resin having excellent strength, a method for producing the same, and a reinforcing material for a resin having an excellent reinforcing effect even if it is made into a dried product.

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

The fibrous cellulose composite resin of this embodiment contains a mixture of fibrous cellulose and a dispersant, and a resin. The fibrous cellulose is made by mixing fine fibers such as cellulose nanofibers (CNF) and microfibrillated cellulose (MFC), for example. Further, the dispersant has at least one functional group selected from a hydroxyl group, a carboxy group, and an amine group.

This fibrous cellulose composite resin can be obtained, for example, by mixing a dispersant with a slurry of fibrous cellulose to form a mixture, drying and pulverizing the mixture to form a powder, and then kneading the mixture with the resin. Hereinafter, it will be described in detail. The fibrous cellulose is also referred to as "cellulose fiber".

(Cellulose nanofiber)
The fibrous cellulose of this embodiment contains fine fibers as a part or a whole thereof. The fine fibers include at least one of cellulose nanofibers and microfibrillated cellulose, preferably cellulose nanofibers.

Cellulose nanofibers have a role of significantly improving the strength of the resin. Cellulose nanofibers can be obtained by defibrating (miniaturizing) the raw material pulp.

As raw material pulp for cellulose nanofibers, for example, wood pulp made from broadleaf tree, coniferous tree, etc., non-wood pulp made from straw, bagasse, cotton, hemp, carrot fiber, etc., recovered waste paper, waste paper, etc. are used as raw materials. One type or two or more types can be selected and used from the used paper pulp (DIP) and the like. The above-mentioned various raw materials may be, for example, in the state of a crushed product (powder) called a cellulosic powder or the like.

However, in order to avoid contamination with impurities as much as possible, it is preferable to use wood pulp as the raw material pulp for the cellulose nanofibers. As the wood pulp, for example, one kind or two or more kinds can be selected and used from chemical pulp such as hardwood kraft pulp (LKP) and softwood kraft pulp (NKP), mechanical pulp (TMP) and the like.

The hardwood kraft pulp may be hardwood bleached kraft pulp, hardwood unbleached kraft pulp, or hardwood semi-bleached kraft pulp. Similarly, the softwood kraft pulp may be softwood bleached kraft pulp, unbleached softwood kraft pulp, or semi-bleached softwood kraft pulp.

Examples of the mechanical pulp include stone ground pulp (SGP), pressurized stone ground pulp (PGW), refiner ground pulp (RGP), chemi-grand pulp (CGP), thermo-grand pulp (TGP), and ground pulp (GP). One or more of the thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), refiner mechanical pulp (RMP), bleached thermomechanical pulp (BTMP) and the like can be selected and used.

Raw pulp can also be pretreated by chemical methods prior to defibration. Pretreatment by chemical method includes, for example, hydrolysis of polysaccharide with acid (acid treatment), hydrolysis of polysaccharide with enzyme (enzyme treatment), swelling of polysaccharide with alkali (alkali treatment), oxidation of polysaccharide with oxidizing agent (acid treatment). Oxidation treatment), reduction of polysaccharides with a reducing agent (reduction treatment), and the like can be exemplified.

When alkali treatment is performed prior to defibration, some of the hydroxyl groups of hemicellulose and cellulose in the pulp are dissociated, and the molecules are anionized, weakening the intramolecular and intermolecular hydrogen bonds, and promoting the dispersion of cellulose fibers in defibration. NS.

Examples of the alkali used for the alkali treatment include sodium hydroxide, lithium hydroxide, potassium hydroxide, aqueous ammonia, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide and the like. Organic alkali or the like can be used. However, from the viewpoint of manufacturing cost, it is preferable to use sodium hydroxide.

When the enzyme treatment, the acid treatment, and the oxidation treatment are performed prior to the defibration, the water retention degree of the cellulose nanofibers can be lowered, the crystallization degree can be increased, and the homogeneity can be increased. In this respect, if the degree of water retention of the cellulose nanofibers is low, dehydration is likely to occur, and the dehydration property of the cellulose fiber slurry is improved.

When the raw material pulp is subjected to enzyme treatment, acid treatment, or oxidation treatment, hemicellulose and the amorphous region of cellulose contained in the pulp are decomposed. As a result, the energy of the miniaturization process can be reduced, and the uniformity and dispersibility of the cellulose fibers can be improved. However, since the pretreatment lowers the aspect ratio of the cellulose nanofibers, it is preferable to avoid excessive pretreatment in terms of using it as a reinforcing material for the resin.

For defibration of raw pulp, for example, beaters, high-pressure homogenizers, homogenizers such as high-pressure homogenizers, stone mill type friction machines such as grinders and grinders, single-screw kneaders, multi-screw kneaders, kneader refiners, jet mills, etc. It can be done by beating the raw pulp using. However, it is preferable to use a refiner or a jet mill.

In the defibration of the raw material pulp, the average fiber diameter, average fiber length, water retention, crystallinity, peak value of pseudo-grain size distribution, pulp viscosity, and B-type viscosity of the dispersion liquid of the obtained cellulose nanofibers are as shown below. It is preferable to obtain a desired value or evaluation.

The average fiber diameter (average fiber width; average diameter of single fibers) of the cellulose nanofibers is preferably 1 to 100 nm, more preferably 10 to 80 nm, and particularly preferably 20 to 60 nm. If the average fiber diameter of the cellulose nanofibers is less than 1 nm, the dehydration property may be deteriorated. Further, in the present embodiment in which the cellulose nanofibers are mixed with the dispersant, the dispersant does not sufficiently cover the cellulose nanofibers (does not sufficiently cling to the dispersant), and the effect of improving the redispersibility may be insufficient. .. On the other hand, if the average fiber diameter of the cellulose nanofibers exceeds 100 nm, the number of cellulose single crystals contained in each cellulose nanofiber increases, so that the reinforcing effect may be lowered.

The average fiber diameter of the cellulose nanofibers can be adjusted by, for example, selection of raw material pulp, pretreatment, defibration and the like.

The method for measuring the average fiber diameter of cellulose nanofibers is as follows.
First, 100 ml of an aqueous dispersion of cellulose nanofibers having a solid content concentration of 0.01 to 0.1% by mass is filtered through a membrane filter made of Teflon (registered trademark), and the solvent is once with 100 ml of ethanol and three times with 20 ml of t-butanol. Replace. Next, it is freeze-dried and coated with osmium to prepare a sample. This sample is observed with an electron microscope SEM image at a magnification of 3,000 to 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. Further, 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.

The average fiber length (length of a single fiber) of the cellulose nanofibers is preferably 0.1 to 1,000 μm, more preferably 0.5 to 500 μm, and particularly preferably 1 to 100 μm. If the average fiber length of the cellulose nanofibers is less than 0.1 μm, a three-dimensional network of the cellulose nanofibers cannot be constructed, and the reinforcing effect may be reduced. On the other hand, if the average fiber length of the cellulose nanofibers exceeds 1,000 μm, the fibers are likely to be entangled with each other, and the redispersibility may not be sufficiently improved.

The average fiber length of the cellulose nanofibers can be adjusted by, for example, selection of raw material pulp, pretreatment, defibration and the like.

The method for measuring the average fiber length of the cellulose nanofibers is the same as in the case of the average fiber diameter, and the length of each fiber is visually measured. The average fiber length is the medium length of the measured value.

The water retention of the cellulose nanofibers is preferably 250 to 500%, more preferably 280 to 490%, and particularly preferably 300 to 480%. If the water retention level of the cellulose nanofibers is less than 250%, the dispersibility of the cellulose nanofibers deteriorates, and there is a possibility that the cellulose nanofibers cannot be uniformly mixed with other fibers such as pulp. On the other hand, when the water retention degree of the cellulose nanofibers exceeds 500%, the water retention capacity of the cellulose nanofibers themselves becomes high, and the dehydration property of the cellulose fiber slurry may deteriorate.

The water retention level of the cellulose nanofibers can be adjusted by, for example, selection of raw material pulp, pretreatment, defibration and the like.

The degree of water retention of cellulose nanofibers is determined by JAPAN TAPPI No. It is a value measured according to 26 (2000).

The degree of cellulose nanofiber crystallinity is preferably 95 to 50%, more preferably 90 to 60%, and particularly preferably 85 to 70%. When the crystallinity of the cellulose nanofibers is within the above range, the strength of the resin can be surely improved.

The crystallinity can be arbitrarily adjusted by, for example, selection of raw material pulp, pretreatment, defibration and the like.

The crystallinity of the cellulose nanofibers is a value measured according to JIS K 0131 (1996).

The peak value in the pseudo particle size distribution curve of the cellulose nanofibers is preferably one peak. In the case of one peak, the cellulose nanofibers have high uniformity of fiber length and fiber diameter, and are excellent in dehydration of the cellulose fiber slurry.

The peak value of the cellulose nanofibers is, for example, 0.1 to 100 μm, preferably 1 to 50 μm, and more preferably 5 to 25 μm.

The peak value of the cellulose nanofibers can be adjusted by, for example, selection of raw material pulp, pretreatment, defibration and the like.

The peak value of the cellulose nanofiber is a value measured according to ISO-13320 (2009). More specifically, first, the volume-based particle size distribution of the aqueous dispersion of cellulose nanofibers is examined using a particle size distribution measuring device. Next, the median diameter of the cellulose nanofibers is measured from this distribution. This median diameter is taken as the peak value.

The pulp viscosity of the cellulose nanofibers is preferably 10.0 to 1.0 cps, more preferably 8.0 to 1.5 cps, and particularly preferably 5.0 to 2.0 cps. The pulp viscosity is the viscosity of the solution after dissolving the cellulose in the copper ethylenediamine solution, and the larger the pulp viscosity is, the higher the degree of polymerization of the cellulose is. When the pulp viscosity is within the above range, while imparting dehydration to the slurry, decomposition of cellulose nanofibers can be suppressed when kneading with the resin, and a sufficient reinforcing effect can be obtained.

The pulp viscosity of the cellulose nanofibers is a value measured according to TAPPI T 230.

If necessary, the cellulose nanofibers obtained by defibration can be dispersed in an aqueous medium and stored as a dispersion liquid prior to mixing with other cellulose fibers. It is particularly preferable that the total amount of the aqueous medium is water (aqueous solution). However, the aqueous medium may be another liquid that is partially compatible with water. As the other liquid, for example, lower alcohols having 3 or less carbon atoms can be used.

The B-type viscosity of the dispersion liquid (concentration 1%) of the cellulose nanofibers is preferably 2,000 to 10 cp, more preferably 1,500 to 30 cp, and particularly preferably 1,300 to 50 cp. When the B-type viscosity of the dispersion is within the above range, mixing with other cellulose fibers becomes easy, and the dehydration property of the cellulose fiber slurry is improved.

The B-type viscosity (solid content concentration 1%) of the dispersion liquid of cellulose nanofibers is a value measured in accordance with "Method for measuring liquid viscosity" of JIS-Z8803 (2011). The B-type viscosity is the resistance torque when the dispersion liquid is stirred, and the higher it is, the more energy is required for stirring.

The content of the cellulose nanofibers in the cellulose fibers is preferably 10 to 95% by mass, more preferably 30 to 93% by mass, and particularly preferably 50 to 90% by mass. If the content of the cellulose nanofibers is less than 10% by mass, the strength of the resin may not be sufficiently improved. On the other hand, when the content of the cellulose nanofibers exceeds 95% by mass, the cellulose nanofibers are strongly aggregated and cannot be dispersed in the resin, and the reinforcing effect may not be sufficient.

(Microfibrillated cellulose)
In this embodiment, microfibrillated cellulose is preferably used together with the cellulose nanofibers instead of the cellulose nanofibers as the fine fibers.

Microfibrillated cellulose is larger in size than cellulose nanofibers, so it is easier to disperse in the resin and build a three-dimensional network.However, cellulose nanofibers are closer to single crystals than microfibrillated cellulose, so they are stronger. It has high physical properties and can be expected to have a reinforcing effect on the resin. In order to take advantage of both, it is desirable to mix in the above ratio.

Microfibrillated cellulose means fibers with a larger average fiber diameter than cellulose nanofibers. Specifically, it is, for example, 0.1 to 15 μm, preferably 0.5 to 10 μm, and more preferably 1 to 5 μm.

When the average fiber diameter of microfibrillated cellulose is less than 0.1 μm, it is no different from that of cellulose nanofibers, and the effect of improving the strength (particularly bending elastic modulus) of the resin cannot be sufficiently obtained. In addition, the defibration time becomes long and a large amount of energy is required. Further, the dehydration property of the cellulose fiber slurry is deteriorated. When dehydration deteriorates, when drying after mixing with a dispersant, a large amount of energy is required for the drying, and if a large amount of energy is applied to the drying, the microfibrillated cellulose may be thermally deteriorated and the strength may be reduced. be. On the other hand, if the average fiber diameter of the microfibrillated cellulose exceeds 15 μm, it is no different from that of pulp, and the reinforcing effect may not be sufficient.

Microfibrillated cellulose can be obtained by defibrating (miniaturizing) the raw material pulp. As the raw material pulp, the same pulp as the cellulose nanofiber can be used, and it is preferable to use the same pulp as the cellulose nanofiber.

The raw material pulp of microfibrillated cellulose can be pretreated and defibrated in the same manner as in the case of cellulose nanofibers. However, the degree of defibration is different, and for example, it is necessary to carry out the defibration within a range in which the average fiber diameter remains 0.1 μm or more. Hereinafter, the differences from the case of cellulose nanofibers will be mainly described.

The average fiber length (average length of single fibers) of microfibrillated cellulose is preferably 0.02 to 3.0 mm, more preferably 0.05 to 2.0 mm, and particularly preferably 0.1 to 1.5 mm. Is. If the average fiber length is less than 0.02 mm, a three-dimensional network of fibers cannot be formed, and the reinforcing effect of the resin may be reduced.

The average fiber length can be arbitrarily adjusted by, for example, selection of raw material pulp, pretreatment, defibration and the like.

The fiber length of the microfibrillated cellulose is preferably 0.2 mm or less in a proportion of 60% or more, more preferably 70% or more, and particularly preferably 75% or more. If the ratio is less than 60%, the reinforcing effect of the resin may not be sufficiently obtained. On the other hand, the fiber length of microfibrillated cellulose has no upper limit of the ratio of 0.2 mm or less, and may be 0.2 mm or less in all cases.

The aspect ratio of the microfibrillated cellulose is preferably 2 to 5,000, more preferably 100 to 1,000. The aspect ratio is a value obtained by dividing the average fiber length by the average fiber width. It is considered that the larger the aspect ratio, the more places in the resin where the resin is caught, so that the reinforcing effect is improved, but on the other hand, the greater the number of catches, the lower the ductility of the resin. It should be noted that there is a finding that when an inorganic filler is kneaded into a resin, the bending strength is improved as the aspect ratio of the filler is larger, but the elongation is significantly reduced.

The fibrillation rate of the microfibrillated cellulose is preferably 1.0 to 30.0%, more preferably 1.5 to 20.0%, and particularly preferably 2.0 to 15.0%. If the fibrillation rate exceeds 30.0%, the contact area with water becomes too wide, so even if the average fiber width can be defibrated within the range of 0.1 μm or more, dehydration may become difficult. There is. On the other hand, if the fibrillation rate is less than 1.0%, there are few hydrogen bonds between the fibrils, and there is a possibility that a strong three-dimensional network cannot be formed.

The crystallinity of the microfibrillated cellulose is preferably 50% or more, more preferably 60% or more. If the crystallinity is less than 50%, the mixing property with pulp and cellulose nanofibers is improved, but the strength of the fibers themselves is lowered, so that the strength may not be guaranteed.

On the other hand, the crystallinity of the microfibrillated cellulose is preferably 90% or less, more preferably 88% or less, and particularly preferably 86% or less. When the crystallinity exceeds 90%, the ratio of strong hydrogen bonds in the molecule increases, the fiber itself becomes rigid, and the redispersibility becomes inferior.

The crystallinity of the microfibrillated cellulose can be arbitrarily adjusted by, for example, selection of raw material pulp, pretreatment, and micronization treatment.

The pulp viscosity of the microfibrillated cellulose is preferably 2 cps or more, and more preferably 4 cps or more. If the pulp viscosity is less than 2 cps, the aggregation of microfibrillated cellulose may not be sufficiently suppressed.

The freeness of the microfibrillated cellulose is preferably 500 cc or less, more preferably 300 cc or less, and particularly preferably 100 cc or less. If the freeness of the microfibrillated cellulose exceeds 500 cc, the average fiber diameter of the microfibrillated cellulose exceeds 10 μm, and there is a possibility that the effect on strength cannot be sufficiently obtained.

The degree of water retention of the microfibrillated cellulose can be arbitrarily adjusted by, for example, selection of raw material pulp, pretreatment, defibration and the like.

The content of microfibrillated cellulose in the cellulose fiber is preferably less than 50% by mass, more preferably less than 40% by mass, and particularly preferably less than 30% by mass. If the content of the microfibrillated cellulose exceeds 50% by mass, the content of the cellulose nanofibers is relatively reduced, and the effect of containing the cellulose nanofibers may not be obtained.

Unless otherwise specified, the method for measuring various physical properties of microfibrillated cellulose is the same as that for cellulose nanofibers.

(slurry)
If necessary, the fibrous cellulose containing fine fibers is dispersed in an aqueous medium to form a dispersion liquid (slurry). It is particularly preferable that the total amount of the aqueous medium is water, but an aqueous medium which is another liquid which is partially compatible with water can also be used. As the other liquid, lower alcohols having 3 or less carbon atoms can be used.

The solid content concentration of the slurry is preferably 0.5 to 5.0% by mass, more preferably 1.0 to 3.0% by mass. If the solid content concentration is less than 0.5% by mass, excessive energy may be required for dehydration and drying. On the other hand, if the solid content concentration exceeds 5.0% by mass, the fluidity of the slurry itself may decrease and the dispersant may not be uniformly mixed.

(Dispersant)
A dispersant is mixed with the slurry of fibrous cellulose. As the dispersant, it is preferable to use one having at least one functional group selected from a hydroxyl group, a carboxy group, and an amine group. More preferably, at least one selected from melamine, urea phosphorylated starch, carbamic acid starch, lecithin, and casein is used. The above dispersant inhibits hydrogen bonds between dried fine fibers. In particular, the above-mentioned melamine, urea phosphorylated starch, carbamic acid starch, lecithin, and casein are easily compatible with both cellulose and resin, and the reinforcing effect of the resin can be further improved. Therefore, when the fine fibers and the resin are kneaded, the fine fibers are surely dispersed (redispersed) in the resin. In addition, the above dispersant also has a role of improving the compatibility of the fine fibers and the resin. In this respect as well, the dispersibility of the fine fibers in the resin is improved. Therefore, the dispersant of this embodiment can be said to be a phase solvent.

It is conceivable to add a phase solvent (drug) separately when kneading the fibrous cellulose and the resin, but rather than adding the chemical at this stage, the fibrous cellulose and the dispersant (drug) are mixed in advance. In this embodiment, the chemicals are more uniformly attached to the fibrous cellulose, and the effect of improving the compatibility with the resin is higher.

Further, for example, polypropylene has a melting point of 160 ° C., and therefore, kneading of the fibrous cellulose and the resin is performed at about 180 ° C. However, if a dispersant (liquid) is added in this state, it dries in an instant. Therefore, there is a method of producing a masterbatch (composite resin having a high concentration such as CNF) using a resin having a low melting point, and then lowering the concentration with a normal resin. However, a resin having a low melting point generally has a low strength. Therefore, according to this method, the strength of the composite resin may decrease.

The mixing amount of the dispersant of this embodiment is preferably 1 to 40 parts by mass, more preferably 5 to 30 parts by mass, and particularly preferably 10 to 20 parts by mass with respect to 100 parts by mass of the cellulose nanofibers. In this regard, when hydroxy acids, glycerin or glycerin derivatives were used, it was necessary to mix 40 parts by mass or more with 100 parts by mass of the cellulose nanofibers. However, when the dispersant of this embodiment is used, it is sufficient to mix 1 part (or more) with 100 parts by mass of the cellulose nanofibers. That is, when the dispersant of this embodiment is used, the mixing amount can be reduced. In this regard, focusing on the fact that the dispersant may inhibit the reinforcing effect of the resin by the cellulose nanofibers, it is a great advantage that the mixing amount of the dispersant can be reduced.

Focusing on the point of improving the dispersibility of the cellulose nanofibers, the mixing of the dispersant improves the reinforcing effect of the resin by the cellulose nanofibers. However, the dispersant must be hydrophilic (has a hydrophilic group) due to the presence of the cellulose nanofibers, and in this respect, it also has an aspect of reducing the strength of the resin. Also, the dispersant may surface on the surface over time. Therefore, it is a great advantage that the mixing amount of the dispersant can be reduced.

(Production method)
The mixture of fibrous cellulose and dispersant is preferably dried and pulverized prior to kneading with the resin into a powder. According to this form, it is not necessary to dry the fibrous cellulose when kneading with the resin, and the thermal efficiency is good. Further, since the dispersant is mixed in the mixture, there is a low possibility that the fine fibers will not be redispersed even if the mixture is dried.

If necessary, the mixture is dehydrated to dehydrate prior to drying. For this dehydration, for example, one or two or more types are selected from dehydrators such as belt presses, screw presses, filter presses, twin rolls, twin wire formers, valveless filters, center disk filters, membrane treatments, and centrifuges. Can be done using.

Mixture drying is, for example, rotary kiln drying, disk drying, air flow drying, medium flow drying, spray drying, drum drying, screw conveyor drying, paddle drying, uniaxial kneading drying, multiaxial kneading drying, vacuum drying, stirring drying. It can be performed by selectively using one type or two or more types from the above.

The dried mixture (dried product) is crushed into a powder. The pulverization of the dried product can be carried out by selecting or using one or more of, for example, a bead mill, a kneader, a disper, a twist mill, a cut mill, a hammer mill and the like.

The average particle size of the powder is preferably 1,000 μm or less, more preferably 800 μm or less, and particularly preferably 600 μm or less. If the average particle size of the powdery substance exceeds 1,000 μm, the kneadability with the resin may be inferior. However, it is not economical because a large amount of energy is required to make the average particle size of the powdery substance less than 1 μm. In addition to controlling the degree of pulverization, the average particle size of the powdery substance can be controlled by classification using a classification device such as a filter or a cyclone.

The bulk specific gravity of the mixture (powder) is preferably 0.03 to 1.0, more preferably 0.1 to 0.8. When the bulk specific density exceeds 1.0, the hydrogen bonds between the fibrous celluloses are stronger and it is not easy to disperse them in the resin. On the other hand, setting the bulk specific density to less than 0.03 is disadvantageous in terms of transfer cost.

The bulk specific density is a value measured according to JIS K7365.

The water content of the mixture (powder) is preferably 50% or less, more preferably 30% or less, and particularly preferably 10% or less. If the water content exceeds 50%, the energy required for kneading with the resin becomes enormous, which is uneconomical.

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

The powdery substance (resin reinforcing material) obtained as described above is kneaded with a resin to obtain a fibrous cellulose composite resin. This kneading can be performed, for example, by a method of mixing the pellet-shaped resin and the powdery material, or by a method of first melting the resin and adding the powdery material to the melted material.

As the resin, at least one of a thermoplastic resin and a thermosetting resin can be used.

Examples of the thermoplastic resin 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, methacrylate and acrylate, and polyamide resins. One kind or two or more kinds can be selected and used from the polycarbonate resin, the polyacetal resin and the like.

However, it is preferable to use at least one of polyolefin and polyester resin. Moreover, it is preferable to use polypropylene as the polyolefin. Further, as the polyester resin, examples of the aliphatic polyester resin include polylactic acid and polycaprolactone, and examples of the aromatic polyester resin include polyethylene terephthalate, which are biodegradable. It is preferable to use a polyester resin having the above (also referred to simply as "biodegradable resin").

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

As the hydroxycarboxylic acid-based aliphatic polyester, for example, a homopolymer of a hydroxycarboxylic acid such as lactic acid, malic acid, glucose acid, or 3-hydroxybutyric acid, or at least one of these hydroxycarboxylic acids is used. One type or two or more types can be selected and used from the polymers and the like. However, it is preferable to use polylactic acid, a polymer of the above hydroxycarboxylic acid excluding lactic acid and lactic acid, polycaprolactone, and a polymer of at least one of the above hydroxycarboxylic acids and caprolactone, and polylactic acid is preferably used. Especially preferred to use.

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

As the caprolactone-based aliphatic polyester, for example, one or more can be selected and used from a homopolymer of polycaprolactone, a copolymer of polycaprolactone and the like and the hydroxycarboxylic acid, and the like. ..

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.

The biodegradable resin may be used alone or in combination of two or more.

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

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

Examples of the inorganic filler 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, and oxidation. Examples thereof include substances, hydroxides, carbon salts, sulfates, silicates, sulfites, and various clay minerals composed of these compounds.

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, hydroxylation. Examples of aluminum, magnesium hydroxide, calcium hydroxide, sodium hydroxide, magnesium carbonate, calcium silicate, claywa lastnite, glass beads, glass powder, silica sand, silica stone, quartz powder, diatomaceous earth, white carbon, glass fiber and the like are exemplified. be able to. A plurality of these inorganic fillers may be contained. Further, it may be contained in recycled paper pulp.

The blending ratio of the fibrous cellulose and the resin is preferably 1 part by mass or more for the fibrous cellulose and 99 parts by mass or less for the resin, and 2 parts by mass or more for the fibrous cellulose and 98 parts by mass or less for the resin. It is more preferable that the amount of fibrous cellulose is 3 parts by mass or more and the amount of resin is 97 parts by mass or less.

Further, the amount of fibrous cellulose is preferably 50 parts by mass or less, the amount of resin is preferably 50 parts by mass or more, the amount of fibrous cellulose is 40 parts by mass or less, the amount of resin is more preferably 60 parts by mass or more, and the amount of fibrous cellulose is 30. It is particularly preferable that the amount of the resin is 70 parts by mass or less and 70 parts by mass or less. However, when the blending ratio of the fibrous cellulose is 10 to 50 parts by mass, the strength of the resin composition, particularly the bending strength and the tensile elastic modulus can be remarkably improved.

The content ratio of the fibrous cellulose and the resin contained in the finally obtained resin composition is usually the same as the above-mentioned blending ratio of the fibrous cellulose and the resin.

(Other compositions)
In addition to the above fine fibers and pulp, the resin composition includes kenaf, jute hemp, Manila hemp, sisal hemp, ganpi, sansho, 楮, banana, pineapple, coco palm, corn, sugar cane, bagasse, palm, papyrus, reeds, etc. It may or may not contain fibers derived from plant materials obtained from various plants such as esparto, sisal, wheat, rice, bamboo, various coniferous trees (sugi and hinoki, etc.), broadleaf trees and cotton. ..

For the resin composition, for example, one or more selected from antistatic agents, flame retardants, antibacterial agents, colorants, radical scavengers, foaming agents, etc., and a range that does not impair the effects of the present invention. Can be added with. These raw materials may be added to the dispersion liquid of fibrous cellulose, added at the time of kneading the mixture and the resin, added to these kneaded products, or added by other methods. However, from the viewpoint of production efficiency, it is preferable to add it at the time of kneading the mixture and the resin.

(Molding process)
The mixture and the kneaded resin can be formed into a desired shape after being kneaded again if necessary. The size, thickness, shape, etc. of this molding are not particularly limited, and may be, for example, sheet-shaped, pellet-shaped, powder-shaped, fibrous-shaped, 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, for example, 90 to 260 ° C, preferably 100 to 240 ° C.

Molding of the kneaded product can be performed by, for example, mold molding, injection molding, extrusion molding, hollow molding, foam molding or the like. Further, the kneaded product may be spun into a fibrous form and mixed with the above-mentioned plant material or the like to form a mat shape or a board shape. The mixed fiber can be, for example, a method of simultaneous deposition by an air ray or the like.

As an apparatus for molding a kneaded product, for example, one or two from injection molding machines, blow molding machines, hollow molding machines, blow molding machines, compression molding machines, extrusion molding machines, vacuum forming machines, pneumatic molding machines and the like. You can select and use more than one species.

The above molding can be performed after kneading, or the kneaded product is once cooled and made into chips by using a crusher or the like, and then the chips are put into a molding machine such as an extrusion molding machine or an injection molding machine. You can also do it. Of course, molding is not an essential requirement of the present invention.

Next, examples of the present invention will be described.
First, the raw material pulp (LBKP: 98% by mass of water) was preliminarily beaten with a Niagara beater for 2 hours and 30 minutes. Next, the defibration treatment was performed twice with a stone mill type disperser (“Super Mass Colloider” manufactured by Masuyuki Sangyo Co., Ltd.) to obtain an aqueous dispersion (concentration 2% by mass) of cellulose nanofibers (fibers). The cellulose nanofibers contained in this aqueous dispersion had one peak in the pseudo particle size distribution of the particle size distribution measurement using laser diffraction, and the water retention degree was 350% or more.

Next, the aqueous dispersion and the aqueous solution of melamine (drug) (concentration: 2% by mass) were stirred with a magnetic stirrer for 60 minutes at 1200 rpm to obtain a mixed solution. The mixing ratio (mass standard) of cellulose nanofibers and melamine was 10: 1.

Next, the mixed solution was dried at 105 ° C. for 6 hours to obtain a film-shaped cellulose nanofiber-containing dried product. The moisture content of this dried product was 9.8% by mass.

The obtained dried product was pulverized so that the average particle size was 1 mm or less.

11 g of a pulverized product (powder), 5 g of polypropylene maleic anhydride, and 85 g of polypropylene (resin) were kneaded with a kneader at 180 ° C. for 1 hour to obtain a cellulose nanofiber composite resin (Test Example 1). Further, as shown in Table 1, cellulose nanofiber composite resins were obtained by variously changing the chemicals (Test Examples 2 to 5; Test Example 6 did not use the chemicals).

The rate of increase in flexural modulus was investigated for each cellulose nanofiber composite resin. The results are shown in Table 1. The flexural modulus and the increase rate, and the details of each drug are as follows. The bulk specific density and the water content are as described above.

(Bending elastic modulus)
Each cellulose nanofiber composite resin was molded into a bending test piece, and the flexural modulus was examined for this molded product. The flexural modulus was measured according to JIS K7171: 2008.

(Up rate)
The flexural modulus of the resin itself was set to 1, and the up rate = the flexural modulus of each cellulose nanofiber composite resin / the flexural modulus of the resin itself.

The present invention can be used as a fibrous cellulose composite resin, a method for producing the same, and a reinforcing material for the resin.

Claims (9)

Contains a mixture of fibrous cellulose and dispersant, and a resin.
The fibrous cellulose contains fibers having an average fiber diameter of 15 μm or less as a part or all of the fibrous cellulose.
The dispersant was selected from among melamine, urea phosphorylated starch, carbamic acid starch, lecithin, and casein having at least one functional group selected from hydroxyl groups, carboxy groups, and amine groups. At least one or more ,
The mixture is a heat-dried pulverized product having a bulk specific gravity of 0.03 to 1.0 and an average particle size of 1 to 1000 μm measured according to JIS K7365.
A fibrous cellulose composite resin characterized by this. The blending ratio of the fibrous cellulose and the fibrous cellulose in the resin is 10 to 50% by mass.
The fibrous cellulose composite resin according to claim 1. The water content of the mixture is 50% or less.
The fibrous cellulose composite resin according to claim 1 or 2. The fibrous cellulose is a fiber having an average fiber diameter of 100 nm or less.
The fibrous cellulose composite resin according to any one of claims 1 to 3. The mixing amount of the dispersant is 1 to 40 parts by mass with respect to 100 parts by mass of the fiber having an average fiber diameter of 100 nm or less.
The fibrous cellulose composite resin according to claim 4. A dispersant is mixed with the slurry of fibrous cellulose to form a mixture, and the mixture is dried and pulverized to form a powder, which is then kneaded with the resin.
Fibers having an average fiber diameter of 15 μm or less are used as part or all of the fibrous cellulose.
The dispersant was selected from melamine, urea phosphorylated starch, carbamic acid starch, lecithin, and casein having at least one functional group selected from hydroxyl groups, carboxy groups, and amine groups. At least one or more ,
The drying is carried out by heating and drying so that the bulk specific gravity of the mixture measured according to JIS K7365 is 0.03 to 1.0 and the average particle size is 1 to 1000 μm.
A method for producing a fibrous cellulose composite resin. The heat drying includes rotary kiln drying, disk drying, air flow drying, medium flow drying, spray drying, drum drying, screw conveyor drying, paddle drying, uniaxial kneading drying, multiaxial kneading drying, vacuum drying, and stirring drying. Select and use one or more of the above,
The method for producing a fibrous cellulose composite resin according to claim 6. As the fibrous cellulose, fibers having an average fiber diameter of 100 nm or less are used, and the fibers are used.
The mixing amount of the dispersant is 1 to 40 parts by mass with respect to 100 parts by mass of the fiber having an average fiber diameter of 100 nm or less.
The method for producing a fibrous cellulose composite resin according to claim 6 or 7. It is a reinforcing material for thermoplastic resin or thermosetting resin.
A mixture of fibrous cellulose and a dispersant,
The fibrous cellulose contains fibers having an average fiber diameter of 15 μm or less as a part or all of the fibrous cellulose.
The dispersing agent is a hydroxyl group, it is selected melamine to have at least any one or more functional groups selected from among carboxyl groups and amine groups, urea phosphorylated starch, carbamic acid starch, lecithin, and from casein At least one of them ,
It is a heat-dried pulverized product having a bulk specific gravity of 0.03 to 1.0 and an average particle size of 1 to 1000 μm measured according to JIS K7365.
A resin reinforcement that is characterized by this.