JP2023064943A - Fibrous cellulose composite resin - Google Patents

Abstract

To provide a fibrous cellulose composite resin that is excellent in flexural modulus and impact resistance.SOLUTION: A fibrous cellulose composite resin includes fibrous cellulose and a resin. The fibrous cellulose composite resin includes an α-olefin copolymer at a ratio of 20 mass% or less. The fibrous cellulose is a carbamate-modified fine fiber having hydroxy groups substituted with carbamate groups. The degree of substitution of the carbamate groups with the hydroxy groups is 0.05-0.5.SELECTED DRAWING: None

Description

The present invention relates to a fibrous cellulose composite resin.

In recent years, the use of fine fibers such as cellulose nanofibers and microfiber cellulose (microfibrillated cellulose) as reinforcing materials for resins has attracted attention. However, since the fine fibers are hydrophilic and the resin is hydrophobic, there is a problem in the dispersibility of the fine fibers in using the fine fibers as a reinforcing material for the resin. Therefore, a method of substituting the hydroxy groups of fine fibers with carbamate groups (carbamation) has been proposed (see, for example, Patent Document 1). According to this proposal, the dispersibility of the fine fibers is improved, resulting in an increase in the rigidity of the resin, resulting in an improvement in the flexural modulus of the resin and the like. However, even if the flexural modulus of the resin increases by carbamate conversion, the impact resistance due to flexibility does not increase. Therefore, it is conceivable to add an "α-olefin copolymer", which is said to be effective in improving impact resistance, to the resin. However, the present inventors have found that simply adding the α-olefin copolymer together with the fine fibers to the resin lowers the flexural modulus of the resin.

JP 2019-1876 A

The problem to be solved by the invention is to provide a fibrous cellulose composite resin excellent in flexural modulus and impact resistance.

As described above, initially, the present inventors added the α-olefin copolymer together with the fine fibers to the resin to improve the flexural modulus of the fine fibers and the impact resistance of the α-olefin copolymer. It was assumed that the improvement effect would be obtained together. However, the addition of the α-olefin copolymer resulted in a decrease in the flexural modulus, although the impact resistance was improved. Against this background, the following measures have been conceived.

(Means according to claim 1)
A fibrous cellulose composite resin containing fibrous cellulose and a resin,
Containing an α-olefin copolymer in a proportion of 20% by mass or less,
The fibrous cellulose is a carbamate-modified fine fiber in which a hydroxy group is substituted with a carbamate group,
The degree of substitution of the carbamate group with respect to the hydroxy group is 0.05 to 0.5,
A fibrous cellulose composite resin characterized by:

(Means according to claim 2)
The fine fibers have an average fiber width of 8 to 25 μm and an average fiber length of 0.1 to 1.00 mm.
The fibrous cellulose composite resin according to claim 1.

(Means according to claim 3)
The fibrillation rate of the fine fibers is 2 to 7%,
The fibrous cellulose composite resin according to claim 1 or 2.

(Means according to claim 4)
containing an acid-modified resin,
Some or all of the carbamate groups ionically bond with the acid groups of the acid-modified resin,
The fibrous cellulose composite resin according to any one of claims 1 to 3.

(Means according to claim 5)
containing a dispersing agent;
The molecular weight of the acid-modified resin is 2 to 2000 times the molecular weight of the dispersant.
The fibrous cellulose composite resin according to claim 4.

(Means according to claim 6)
The crystallinity of the fine fibers is 50 to 95%,
The fibrous cellulose composite resin according to any one of claims 1 to 5.

(Means according to claim 7)
The pulp viscosity of the fine fibers is 2 cps or more,
The fibrous cellulose composite resin according to any one of claims 1-6.

(Means according to claim 8)
The fine fibers have a zeta potential of -150 to 20 mV,
The fibrous cellulose composite resin according to any one of claims 1-7.

(Means according to claim 9)
The fine fibers have a water retention rate of 80 to 400%,
The fibrous cellulose composite resin according to any one of claims 1-8.

According to the present invention, a fibrous cellulose composite resin excellent in flexural modulus and impact resistance is obtained.

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 this embodiment is a fibrous cellulose composite resin containing fibrous cellulose (hereinafter also referred to as "cellulose fiber") and a resin. This fibrous cellulose composite resin further contains an α-olefin copolymer in a predetermined proportion, and the fibrous cellulose is a carbamate-modified fine grain having a hydroxyl group (—OH group) substituted with a carbamate group at a predetermined degree of substitution. Fiber. As described above, the inclusion of an α-olefin copolymer improves the impact resistance, but a higher content of the α-olefin copolymer lowers the flexural modulus. Therefore, it is necessary to limit the content of the α-olefin copolymer to a predetermined amount or less, but limiting the content of the α-olefin copolymer results in insufficient impact resistance. However, by carbamate-izing the fine fibers as in the present embodiment, the impact resistance is improved, and as a result, the disadvantage due to the limitation of the content of the α-olefin copolymer is compensated. Therefore, according to this embodiment, the fibrous cellulose composite resin is excellent in both bending elastic modulus and impact resistance. The addition of fine fibers also contributes to the improvement of the bending elastic modulus, but the significant significance of this embodiment is that the addition of fine fibers contributes to the improvement of impact resistance by means of carbamate conversion. A detailed description will be given below.

(fine fiber)
In this embodiment, cellulose nanofibers or microfiber cellulose (microfibrillated cellulose), which are fine fibers, are used as part or all of the fibrous cellulose, preferably microfiber cellulose. The use of microfiber cellulose significantly improves the reinforcing effect of the resin. In addition, in the washing step for the purpose of removing urea or the like remaining unreacted after the carbamate reaction, if the fibers to be washed are cellulose nanofibers, the dehydration is very poor. In contrast, microfiber cellulose is easier to modify with carbamate groups (carbamate formation) than cellulose nanofiber, which is also a fine fiber, from the viewpoint of dehydration. However, it is more preferable to carbamate the cellulose raw material prior to micronization, in which case the cellulose raw material will be washed, so microfiber cellulose and cellulose nanofibers are equivalent.

In the present embodiment, microfiber cellulose means fibers having a larger average fiber diameter (width) than cellulose nanofibers. Specifically, it is, for example, 0.1 to 28 μm, preferably 8 to 25 μm, more preferably 9 to 20 μm, particularly preferably 10 to 19 μm. If the average fiber diameter of the microfiber cellulose is less than 0.1 μm (less than), it is no different from cellulose nanofiber, and there is a possibility that the effect of improving the strength (especially bending elastic modulus) of the resin cannot be sufficiently obtained. . In addition, defibration takes a long time, and a large amount of energy is required. Furthermore, the dewaterability of the cellulose fiber slurry deteriorates. When dehydration deteriorates, a large amount of energy is required for drying, and if a large amount of energy is applied to drying, the microfiber cellulose may be thermally degraded, resulting in a decrease in strength. Furthermore, if the average fiber diameter of the microfiber cellulose is less than 8 μm, in the present embodiment using the α-olefin copolymer, there is a possibility that the effect of improving the strength (particularly the flexural modulus) of the resin may not be sufficiently obtained. This is because the α-olefin copolymer and other resins are not completely compatible and may form a sea-island state separated into two phases, but if the average fiber diameter of the microfiber cellulose is less than 8 μm, the α-olefin copolymer and other resins, and as a result, the reinforcing strength of the composite resin as a whole is not improved.

On the other hand, if the average fiber diameter of the microfiber cellulose exceeds (exceeds) 28 μm, the number of fibers decreases, so that the fibers do not interact with each other and the reinforcing effect may not be sufficient. In addition, if the average fiber width of the microfiber cellulose exceeds 25 μm, the fiber itself becomes a starting point of damage in the same way as a foreign object when an impact is applied, and damage, damage, etc. spreads from the starting point, and impact resistance is improved. may decrease.

The method for measuring the average fiber diameter of microfiber cellulose is as follows.
First, 100 ml of an aqueous dispersion of fine fibers (microfiber cellulose) having a solid content concentration of 0.01 to 0.1% by mass was filtered through a Teflon (registered trademark) membrane filter, filtered once with 100 ml of ethanol, and then filtered with 20 ml of t-butanol. Replace the solvent with 3 times. 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 3,000 times 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. 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 values is taken as the average fiber diameter.

Microfiber cellulose can be obtained by defibrating (refining) a cellulose raw material (hereinafter also referred to as "raw material pulp"). Raw material pulp includes, for example, wood pulp made from broad-leaved trees, coniferous trees, etc., non-wood pulp made from straw, bagasse, cotton, hemp, pistil fibers, etc., and waste paper pulp made from recovered waste paper, waste paper, etc. (DIP) or the like can be selected and used. The various raw materials described above may be, for example, in the form of pulverized (powdered) material such as cellulose powder.

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

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

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

The raw material pulp can be pretreated by a chemical method prior to defibration (this fibrillation is preferably performed after carbamate conversion). Examples of chemical pretreatments include hydrolysis of polysaccharides with acid (acid treatment), hydrolysis of polysaccharides with enzymes (enzyme treatment), swelling of polysaccharides with alkali (alkali treatment), and oxidation of polysaccharides with an oxidizing agent ( oxidation treatment), reduction of polysaccharides with a reducing agent (reduction treatment), and the like. However, as the chemical pretreatment, 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 enzymatic treatment will be described in detail below.

At least one of a cellulase enzyme and a hemicellulase enzyme is preferably used as the enzyme used for the enzymatic treatment, and it is more preferable to use both together. The use of these enzymes makes the fibrillation of cellulosic raw materials easier. Cellulase enzymes cause decomposition of cellulose in the presence of water. In addition, hemicellulase enzymes cause decomposition of hemicellulose in the presence of water.

Cellulase enzymes include, for example, Trichoderma genus, Acremonium genus, Aspergillus genus, Phanerochaete genus, Trametes genus genus Humicola, genus Bacillus, genus Schizophyllum, genus Streptomyces, genus Pseudomonas, etc. Enzymes can be used. These cellulase enzymes can be purchased as reagents or commercial products. Commercially available products include, for example, cellulucine T2 (manufactured by HPI), Meicerase (manufactured by Meiji Seika Co., Ltd.), Novozym 188 (manufactured by Novozym), Multifect CX10L (manufactured by Genencore), cellulase enzyme GC220 (manufactured by Genencore). ) etc. can be exemplified.

As the cellulase enzyme, either EG (endoglucanase) or CBH (cellobiohydrolase) can be used. EG and CBH may be used alone or in combination. It may also be used in combination with a hemicellulase enzyme.

Examples of hemicellulase enzymes that can be used include xylanase, an enzyme that degrades xylan, mannase, an enzyme that degrades mannan, and arabanase, an enzyme that degrades araban. can. Pectinase, which is an enzyme that degrades pectin, can also be used.

Hemicellulose is a polysaccharide excluding pectins present between cellulose microfibrils in plant cell walls. Hemicelluloses are very diverse and differ between wood types and cell wall layers. Glucomannan is the main component in the secondary walls of coniferous trees, and 4-O-methylglucuronoxylan is the main component in the secondary walls of hardwoods. Therefore, when obtaining fine fibers from softwood bleached kraft pulp (NBKP), it is preferable to use mannase. In addition, when obtaining fine fibers from hardwood bleached kraft pulp (LBKP), it is preferable to use xylanase.

The amount of enzyme added to the cellulose fiber is determined, for example, by the type of enzyme, the type of raw material wood (coniferous or hardwood), the type of mechanical pulp, and the like. However, the amount of the enzyme added to the cellulose fiber is preferably 0.1-3% by mass, more preferably 0.3-2.5% by mass, and particularly preferably 0.5-2% by mass. If the added amount of the enzyme is less than 0.1% by mass, there is a possibility that the effect of the addition of the enzyme cannot be sufficiently obtained. On the other hand, if the added amount of the enzyme exceeds 3% by mass, cellulose may be saccharified and the yield of fine fibers may decrease. Moreover, there is also a problem that an improvement in the effect commensurate with an increase in the amount added cannot be recognized.

When a cellulase enzyme is used as the enzyme, the pH during the enzyme treatment is preferably in the weakly acidic range (pH=3.0 to 6.9) from the viewpoint of the reactivity of the enzyme reaction. On the other hand, when a hemicellulase enzyme is used as the enzyme, the pH during the enzyme treatment is preferably in the weakly alkaline range (pH=7.1 to 10.0).

The temperature during enzyme treatment is preferably 30 to 70°C, more preferably 35 to 65°C, and particularly preferably 40 to 60°C, regardless of whether a cellulase enzyme or a hemicellulase enzyme is used as the enzyme. . If the temperature during the enzyme treatment is 30° C. or higher, the enzyme activity is less likely to decrease and the treatment time can be prevented from becoming longer. On the other hand, if the temperature during the enzyme treatment is 70° C. or lower, deactivation of the enzyme can be prevented.

The enzymatic treatment time is determined by, for example, the type of enzyme, the temperature of the enzymatic treatment, the pH at the time of the enzymatic treatment, and the like. However, the general enzymatic treatment time is 0.5 to 24 hours.

After enzymatic treatment, the enzyme is preferably deactivated. Methods for inactivating the enzyme include, for example, a method of adding an alkaline aqueous solution (preferably pH 10 or higher, more preferably pH 11 or higher), a method of adding hot water at 80 to 100°C, and the like.

Next, the method of alkali treatment will be described.
Alkali treatment prior to fibrillation dissociates some of the hemicellulose and cellulose hydroxyl groups in the cellulose fibers, anionizing the molecules, weakening intramolecular and intermolecular hydrogen bonds, and promoting the dispersion of cellulose raw materials during fibrillation. be done.

Alkali used for alkali treatment include, for example, sodium hydroxide, lithium hydroxide, potassium hydroxide, aqueous ammonia solution, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, and the like. An organic alkali or the like can be used. However, from the viewpoint of production cost, it is preferable to use sodium hydroxide.

If enzyme treatment, acid treatment, or oxidation treatment is performed prior to fibrillation, the water retention of cellulose fibers can be lowered, the degree of crystallinity can be increased, and homogeneity can be increased. In this regard, if the water retention of the cellulose fibers is low, dehydration is facilitated, and the dewaterability of the cellulose fiber slurry is improved.

Enzymatic treatment, acid treatment, or oxidation treatment of cellulose fibers decomposes the hemicellulose and amorphous regions of cellulose in the pulp. As a result, the defibration energy can be reduced, and the uniformity and dispersibility of the cellulose fibers can be improved. However, pretreatment reduces the aspect ratio of the microfibrous cellulose, so it is preferable to avoid excessive pretreatment.

For fibrillation of cellulose fibers, for example, beaters, high-pressure homogenizers, homogenizers such as high-pressure homogenizers, grinders, stone mills such as grinders, single-screw kneaders, multi-screw kneaders, kneader refiners, jet mills, etc. It can be carried out by beating the raw material pulp using However, it is preferable to use a refiner or a jet mill.

The average fiber length (average length of single fibers) of microfiber cellulose is, for example, 0.1 to 1.00 mm, preferably 0.15 to 0.9 mm, more preferably 0.20 to 0.8 mm. If the average fiber length is less than 0.1 mm, the effect of fiber reinforcement is insufficient, and the flexibility-imparting effect of the α-olefin copolymer may be greatly exhibited, and the reinforcing effect of the resin may be reduced. Moreover, if the average fiber length is less than 0.15 mm, the same problem as the above-described average fiber diameter of less than 8 μm may occur.

On the other hand, if the average fiber length exceeds 1.00 mm, there is a risk that the reinforcing effect will be insufficient because the fiber length is the same as that of raw material pulp. Moreover, if the average fiber length exceeds 1.00 mm, the same problem as the above-described average fiber diameter exceeding 25 μm may occur.

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

The fiber length of the microfiber cellulose is preferably 20% or more, more preferably 40% or more, and particularly preferably 60% or more in a ratio of 0.2 mm or less (Fine ratio). If the ratio is less than 20%, the reinforcing effect of the resin may not be obtained sufficiently. On the other hand, the fiber length of the microfibrous cellulose does not have a percentage upper limit of 0.2 mm or less, and may all be 0.2 mm or less.

The aspect ratio of the microfiber cellulose is preferably 2-15,000, more preferably 10-10,000. If the aspect ratio is less than 2, a three-dimensional network cannot be constructed, and the reinforcing effect may be insufficient. On the other hand, if the aspect ratio exceeds 15,000, the entanglement of the microfiber cellulose becomes high, and there is a possibility that the dispersion in the resin becomes insufficient.

The fibrillation rate of the microfibrous cellulose is, for example, 1.0-30.0%, preferably 2-7%, more preferably 2-6%, particularly preferably 3-5%. If the fibrillation rate exceeds 30.0%, the contact area with water becomes too large, so even if the average fiber width is within the range of 0.1 μm or more, dehydration may become difficult. There is In addition, when the fibrillation rate exceeds 7%, the fibers are bundled together during the kneading process, and when an impact is applied from the outside, the bundled portion of the fibers acts like a foreign object and breaks from there, resulting in bending physical properties. and impact resistance may decrease.

On the other hand, if the fibrillation rate is less than 1.0%, hydrogen bonding between fibrils is reduced, and a strong three-dimensional network may not be formed. On the other hand, if the fibrillation rate is less than 2%, there is a possibility that the interfacial adhesiveness will decrease due to the decrease in the portion that comes into contact with the resin, and the impact resistance will decrease.

The fiber length and fibrillation rate of cellulose fibers are measured by a fiber analyzer "FS5" manufactured by Valmet.

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%, although the miscibility with pulp and cellulose nanofibers is improved, the strength of the fibers themselves is reduced, so there is a risk that the strength of the resin cannot be improved. On the other hand, the crystallinity of the microfibrous cellulose is preferably 95% or less, more preferably 90% or less, particularly preferably 85% or less. If the degree of crystallinity exceeds 95%, the proportion of strong hydrogen bonds in the molecule increases, the fiber itself becomes rigid, and the impact resistance deteriorates.

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

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

The pulp viscosity of the microfiber cellulose is preferably 2 cps or greater, more preferably 4 cps or greater. If the pulp viscosity of the microfiber cellulose is less than 2 cps, it may be difficult to suppress the aggregation of the microfiber cellulose. As described above, aggregation of cellulose fibers is not preferable for improving impact resistance.

Pulp viscosity of microfiber cellulose is a value measured according to TAPPI T 230.

The freeness of the microfibrous cellulose is preferably 500 ml or less, more preferably 300 ml or less, particularly preferably 100 ml or less. If the freeness of the cellulose microfibers exceeds 500 ml, the average fiber diameter of the cellulose microfibers exceeds 10 μm, and there is a risk that the effect of improving the strength of the resin will not be sufficiently obtained.

The freeness of microfiber cellulose is a value measured according to JIS P8121-2 (2012).

The zeta potential of the microfiber cellulose is preferably −150 to 20 mV, more preferably −100 to 0 mV, particularly preferably −80 to −10 mV. If the zeta potential is less than -150 mV, the compatibility with the resin may be significantly reduced and the reinforcing effect may be insufficient. On the other hand, when the zeta potential exceeds 20 mV, the dispersion stability may deteriorate.

The water retention of the microfibrous cellulose is preferably 80-400%, more preferably 90-350%, particularly preferably 100-300%. If the water retention is less than 80%, the reinforcing effect may be insufficient because it is the same as the raw material pulp. On the other hand, if the water retention exceeds 400%, the dewatering property tends to be poor and aggregation tends to occur. In this regard, the water retention of the microfiber cellulose can be lowered by substituting the hydroxy group of the fiber with a carbamate group, and the dehydration and drying properties can be improved.

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

The water retention rate of microfiber cellulose is determined according to JAPAN TAPPI No. 26 (2000).

The α-cellulose content of the microfibrous cellulose is preferably 80-93%, more preferably 83-91%, particularly preferably 85-90%. If the α-cellulose content is less than 80%, there are too many components other than the fibers of the microfiber cellulose, which may cause coloring and odor when used as a composite resin, and the impact strength and bending elastic modulus may not reach the desired values. Even if it satisfies the requirement, there is a possibility that a large limitation will occur in the application. On the other hand, if the α-cellulose content exceeds 93%, the compatibility with the α-olefin copolymer and other resins will be insufficient, the flexibility of the α-olefin copolymer will not be exhibited well, and the impact strength will decrease. , flexural modulus and impact strength may not be compatible.

The α-cellulose content can be adjusted to a desired value by, for example, treating the cellulose raw material with carbamate and washing to remove unnecessary components from the cellulose raw material.

The content of microfibrous cellulose in the cellulose fibers is preferably 60-100% by weight, more preferably 70-99% by weight, particularly preferably 80-98% by weight. If the microfiber cellulose content is less than 60% by mass, a sufficient reinforcing effect may not be obtained. If the content of microfiber cellulose is less than 60% by mass, the content of pulp and cellulose nanofibers will relatively increase, and the effect of containing microfiber cellulose may not be obtained.

Microfibrous cellulose is provided with carbamate groups, for example, by the method described below. That is, the microfiber cellulose is brought into a state in which carbamate (ester of carbamic acid) is introduced. A carbamate group is a group represented by --O--CO--NH--, for example, a group represented by --O--CO--NH ₂ , --O--CONHR, --O--CO--NR ₂ and the like. That is, the carbamate group can be represented by the following structural formula (1).

Here, n represents an integer of 1 or more. Each R is independently a saturated straight-chain hydrocarbon group, a saturated branched-chain hydrocarbon group, a saturated cyclic hydrocarbon group, an unsaturated straight-chain hydrocarbon group, an unsaturated branched-chain hydrocarbon group, an aromatic and/or derived groups thereof.

Examples of saturated linear hydrocarbon groups include linear alkyl groups having 1 to 10 carbon atoms such as methyl, ethyl and propyl groups.

Examples of saturated branched hydrocarbon groups include branched chain alkyl groups having 3 to 10 carbon atoms such as isopropyl group, sec-butyl group, isobutyl group and tert-butyl group.

Examples of saturated cyclic hydrocarbon groups include cycloalkyl groups such as cyclopentyl, cyclohexyl and norbornyl groups.

Examples of unsaturated linear hydrocarbon groups include linear alkenyl groups having 2 to 10 carbon atoms such as ethenyl, propen-1-yl, propen-3-yl, ethynyl, and propyne-1. -yl group, propyn-3-yl group and other linear alkynyl groups having 2 to 10 carbon atoms.

Examples of unsaturated branched hydrocarbon groups include branched chain alkenyl groups having 3 to 10 carbon atoms such as propen-2-yl group, buten-2-yl group and buten-3-yl group, butyne-3 A branched alkynyl group having 4 to 10 carbon atoms such as -yl group can be mentioned.

Examples of aromatic groups include phenyl group, tolyl group, xylyl group, naphthyl group and the like.

As the derivative group, the above saturated straight-chain hydrocarbon group, saturated branched-chain hydrocarbon group, saturated cyclic hydrocarbon group, unsaturated straight-chain hydrocarbon group, unsaturated branched-chain hydrocarbon group and aromatic group Groups in which one or more hydrogen atoms possessed are substituted with a substituent (eg, a hydroxy group, a carboxy group, a halogen atom, etc.) can be mentioned.

In microfibrous cellulose with carbamate groups (carbamate introduced), some or all of the more polar hydroxy groups are replaced with less polar carbamate groups. Therefore, the microfiber cellulose has low hydrophilicity and high affinity with low polarity resins and the like. As a result, the microfiber cellulose is excellent in uniform dispersibility with the resin. Also, the microfiber cellulose slurry has a low viscosity and is easy to handle.

Cellulose is a polymer having anhydroglucose as a structural unit, and has three hydroxy groups per structural unit. Thus, if all hydroxy groups are replaced with carbamate groups, the degree of substitution will be 3. The degree of substitution of carbamate groups is determined by nitrogen determination by the Kjeldahl method.

<Carbamate formation>
Regarding the introduction of carbamate into microfiber cellulose (the cellulose raw material when carbamate is formed before fibrillation) (carbamation), there are two methods: carbamate the cellulose raw material and then refine it; There is a method for carbamate conversion from. In this regard, in this specification, defibration of the cellulose raw material is described first, and then carbamate formation (modification) is described. However, defibration and carbamate can be performed either first. However, it is preferable to perform carbamate formation first and then defibrate. This is because the cellulose raw material before defibration has a high dehydration efficiency, and the cellulose raw material is easily defibrated by the heating accompanying carbamate formation.

The process of carbamating cellulose fibers (microfiber cellulose, cellulosic raw material, etc.) can be divided mainly into, for example, mixing, removing, and heating. In addition, the mixing step and the removing step can also be collectively referred to as a preparation step for preparing a mixture to be subjected to the heating step.

In the mixing step, the cellulose fibers and urea or a urea derivative (hereinafter also simply referred to as “urea, etc.”) are mixed in a dispersion medium.

Examples of urea and urea derivatives include urea, thiourea, biuret, phenylurea, benzylurea, dimethylurea, diethylurea, tetramethylurea, and compounds in which hydrogen atoms of urea are substituted with alkyl groups. can. These urea or urea derivatives can be used singly or in combination. However, it is preferable to use urea because it is inexpensive, industrially easy to use, highly soluble in water, and can be brought into contact with the raw material pulp with a chemical solution using an aqueous solution with less environmental impact.

The lower limit of the mixing mass ratio of urea etc. to cellulose fibers (cellulose fibers/urea etc.) is preferably 100/10, more preferably 100/20. On the other hand, the upper limit is preferably 100/100, more preferably 100/50. By setting the mixing mass ratio to 100/10 or more, the efficiency of carbamate formation is improved. On the other hand, if the mixing mass ratio exceeds 100/50, the carbamate reaction may proceed too much.

The dispersion medium is usually water. However, other dispersion media such as alcohols and ethers, and mixtures of water and other dispersion media may also be used.

In the mixing step, for example, cellulose fibers and urea may be added to water, cellulose fibers may be added to an aqueous solution of urea or the like, or urea or the like may be added to slurry containing cellulose fibers. Moreover, in order to mix uniformly, you may stir after addition. Furthermore, the dispersion containing cellulose fibers and urea may contain other components.

In the removing step, the dispersion medium is removed from the dispersion containing cellulose fibers, urea, etc. obtained in the mixing step. By removing the dispersion medium, urea and the like can be efficiently reacted in the subsequent heating step.

The removal of the dispersion medium is preferably carried out by volatilizing the dispersion medium by heating. According to this method, only the dispersion medium can be efficiently removed while leaving components such as urea.

The lower limit of the heating temperature in the removal step is preferably 50°C, more preferably 70°C, and particularly preferably 90°C when the dispersion medium is water. By setting the heating temperature to 50° C. or higher, the dispersion medium can be efficiently volatilized (removed). On the other hand, the upper limit of the heating temperature is preferably 120°C, more preferably 100°C. If the heating temperature exceeds 120° C., the dispersion medium and urea may react with each other and urea may decompose alone.

The heating time in the removing step can be appropriately adjusted according to the solid content concentration of the dispersion. Specifically, it is, for example, 6 to 24 hours.

In the heating step following the removing step, the mixture of cellulose fibers and urea or the like is heat-treated. In this heating step, some or all of the hydroxyl groups of the cellulose fibers react with urea or the like and are substituted with carbamate groups. More specifically, when urea or the like is heated, it decomposes into isocyanic acid and ammonia as shown in the following reaction formula (1). Isocyanic acid is highly reactive and, for example, forms a carbamate on the hydroxyl group of cellulose as shown in the following reaction formula (2).

NH ₂ -CO-NH ₂ →H-N=C=O + NH ₃ (1)

Cell-OH + H-N=C=O → Cell-O-CO-NH ₂ (2)

The lower limit of the heating temperature in the heating step is preferably 120°C, more preferably 130°C, particularly preferably the melting point of urea (about 134°C) or higher, still more preferably 140°C, most preferably 150°C. By setting the heating temperature to 120° C. or higher, carbamate formation is efficiently performed. The upper limit of the heating temperature is preferably 200°C, more preferably 180°C, and particularly preferably 170°C. If the heating temperature exceeds 200°C, the cellulose fibers may be decomposed and the reinforcing effect may be insufficient.

The lower limit of the heating time in the heating step is preferably 1 minute, more preferably 5 minutes, particularly preferably 30 minutes, still more preferably 1 hour, most preferably 2 hours. By setting the heating time to 1 minute or longer, the carbamate reaction can be reliably carried out. On the other hand, the upper limit of the heating time is preferably 15 hours, more preferably 10 hours. If the heating time exceeds 15 hours, it is not economical, and 15 hours is sufficient for carbamate formation.

The above heat treatment is preferably performed under an acidic condition. Carrying out the reaction in an acidic environment ensures the carbamate formation. The upper limit of the pH of the mixture in the heating step is preferably 6, more preferably 5, and particularly preferably 4. On the other hand, the lower limit of pH is preferably 1, more preferably 2, particularly preferably 3. This pH adjustment can be performed by adding an acidic compound (eg, acetic acid, citric acid, etc.) or an alkaline compound (eg, sodium hydroxide, calcium hydroxide, etc.) to the mixture.

As a device for heating in the heating step, for example, a hot air dryer, a paper machine, a dry pulp machine, or the like can be used.

The heat-treated mixture may be washed. This washing may be performed with water or the like. By this washing, unreacted and remaining urea and the like can be removed.

In this embodiment, cellulose nanofibers can be included as fibrous cellulose (cellulose fibers) together with microfiber cellulose. Cellulose nanofibers are fine fibers like microfiber cellulose, and have a role to complement microfiber cellulose for improving the strength of resin. However, if possible, it is preferable to use only microfiber cellulose without containing cellulose nanofibers as fine fibers, but if cellulose nanofibers are contained, the following cellulose nanofibers are recommended.

First, cellulose nanofibers can be obtained by fibrillating (miniaturizing) raw material pulp (cellulose raw material). As the raw material pulp, the same pulp as the microfiber cellulose can be used, and it is preferable to use the same pulp as the microfiber cellulose.

The raw material pulp for cellulose nanofibers can be pretreated and defibrated in the same manner as for microfiber cellulose. However, the degree of fibrillation is different and, for example, the average fiber diameter should be less than 0.1 μm. In the following, differences from the case of microfiber cellulose will be mainly described.

The average fiber diameter (average fiber width, average diameter of single fibers) of cellulose nanofibers is preferably 4 to 100 nm, more preferably 10 to 80 nm. If the average fiber diameter of the cellulose nanofibers is less than 4 nm, the dewaterability may deteriorate. In addition, in a form in which the cellulose nanofibers are mixed with the dispersant, the dispersant may not sufficiently cover the cellulose nanofibers (they may not sufficiently cling to the cellulose nanofibers), and the dispersibility may not be sufficiently improved. On the other hand, if the average fiber diameter of cellulose nanofiber exceeds 100 nm, it cannot be said to be cellulose nanofiber.

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

The measurement method for the physical properties of cellulose nanofibers is the same as that for microfiber cellulose, unless otherwise specified. The method for measuring the average fiber diameter of pulp is as follows.
First, 100 ml of an aqueous dispersion of pulp having 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 100 times to 1000 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 values is taken as the average fiber diameter.

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

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

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

The cellulose nanofiber crystallinity is preferably 95-50%, more preferably 90-60%. If the crystallinity of the cellulose nanofibers is within the above range, the strength of the resin can be reliably improved.

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

The cellulose nanofiber pulp viscosity is preferably 1.0 cps or more, more preferably 2.0 cps or more. The pulp viscosity is the viscosity of the solution after dissolving cellulose in the copper ethylenediamine solution, and the higher the pulp viscosity, the higher the degree of polymerization of cellulose. If the pulp viscosity is 1.0 cps or more, dehydration is imparted to the slurry, decomposition of the cellulose nanofibers is suppressed during kneading with the resin, and a sufficient reinforcing effect can be obtained.

Cellulose nanofibers obtained by fibrillation can be dispersed in an aqueous medium to prepare a dispersion, if necessary, prior to mixing with other cellulose fibers. It is particularly preferred that the aqueous medium is entirely water (aqueous solution). However, the aqueous medium may be another liquid partially compatible with water. As other liquids, for example, lower alcohols having 3 or less carbon atoms can be used.

The B-type viscosity of the cellulose nanofiber dispersion (1% concentration) is preferably 10 to 2,000 cp, more preferably 30 to 1,500 cp. When the B-type viscosity of the dispersion is within the above range, mixing with other cellulose fibers is facilitated, and the dewaterability of the cellulose fiber slurry is improved.

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

The content of cellulose nanofibers in the cellulose fibers is preferably 40% by mass or less, more preferably 20% by mass or less. If the content of cellulose nanofibers exceeds 40% by mass, the cellulose nanofibers are strongly agglomerated and cannot be dispersed in the resin, resulting in insufficient reinforcing effect and impact resistance. As described above, it is most preferable not to mix cellulose nanofibers, that is, to have a content of 0% by mass.

Cellulose nanofibers can be carbamate if desired, such as by methods similar to microfiber cellulose. However, carbamate conversion of cellulose nanofibers is usually difficult.

Fibrous cellulose can contain pulp in addition to fine fibers. Pulp has the role of greatly improving the dewaterability of the cellulose fiber slurry. However, the content of pulp is preferably within a predetermined range (described below).

The pulp content in the cellulose fibers is preferably 40% by mass or less, more preferably 20% by mass or less. If the pulp content exceeds 40% by mass, the content of fine fibers is reduced as a result, and the strength of the resin may not be ensured. As with the cellulose nanofibers, it is most preferable not to mix the pulp, that is, the content is 0% by mass.

As the pulp, the same pulp as the raw material pulp of microfiber cellulose or the like can be used, and it is preferable to use the same pulp as the raw material pulp of microfiber cellulose. Using the same pulp as the raw material pulp for the microfiber cellulose improves the affinity of the cellulose fibers, resulting in improved homogeneity of the cellulose fiber slurry.

If necessary, the fibrous cellulose containing fine fibers is dispersed in an aqueous medium to form a dispersion (slurry). It is particularly preferred that the entire amount of the aqueous medium is water, but it is also possible to 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 slurry is preferably 0.1-10.0% by mass, more preferably 0.5-5.0% by mass. If the solid content concentration is less than 0.1% by mass, excessive energy may be required during dehydration and drying. On the other hand, if the solid content concentration exceeds 10.0% by mass, the fluidity of the slurry itself may be lowered, and the dispersant may not be uniformly mixed.

(α-olefin copolymer)
The fibrous cellulose composite resin of this embodiment contains an α-olefin copolymer. α-olefin copolymers are polymers obtained by copolymerizing α-olefins (olefins with a carbon-carbon double bond at the end) and monomers such as ethylene and propylene, and α-olefins with long side chains are present. . Therefore, since the polymer chains are difficult to align and do not crystallize or become rigid, the composite resin can be given flexibility unlike polyethylene or polypropylene, and the impact resistance can be improved. However, since the α-olefin copolymer impairs the rigidity of the composite resin, the rigidity is maintained by fiber reinforcement. Fracture progresses as a starting point, and even if the rigidity is maintained, the effect of improving the impact resistance due to the addition of the α-olefin copolymer is not sufficiently exhibited. Therefore, in the present embodiment, by modifying the cellulose raw material with carbamate groups, the compatibility between the cellulose raw material and the α-olefin copolymer is improved, and both impact resistance and rigidity are achieved.

From the above viewpoints, the degree of substitution of the carbamate group is preferably 0.05 to 0.5, more preferably 0.1 to 0.4, and particularly preferably 0.2 to 0.3. By setting the degree of substitution of the carbamate group to 0.05 or more, the compatibility between the α-olefin copolymer and the cellulose raw material is sufficiently improved, and the effect of introducing the carbamate group can be reliably exhibited. On the other hand, if the degree of substitution exceeds 0.5, the compatibility with the α-olefin copolymer is sufficient, but the reinforcing property of the fiber itself is impaired, and the flexibility imparted by the α-olefin copolymer may not be covered. There is

Examples of α-olefins include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene and 1-hexadecene. , 1-octadecene, and linear units such as 1-eicosene, cyclopentene, cycloheptene, norbornene, 5-methyl-2-norbornene, tetracyclododecene, 2-methyl-1,4,5,8-dimethano- Cyclic units such as 1,2,3,4,4a,5,8,8a-octahydronaphthalene and the like are included.

The mixing ratio of the α-olefin copolymer is preferably 20 parts by mass or less, more preferably 1 to 18 parts by mass, particularly preferably 3 to 15 parts by mass, in the total amount of the composite resin. When the mixing ratio of the α-olefin copolymer exceeds 1% by mass, sufficient flexibility is imparted to the composite resin, and the possibility of insufficient impact resistance of the composite resin can be reduced. On the other hand, if the mixing ratio exceeds 20% by mass, too much flexibility is imparted, and even if the compatibility with the fibers is high, the reinforcing properties of the fibers cannot be sufficiently exhibited, resulting in insufficient rigidity.

(Acid-modified resin)
The fibrous cellulose composite resin of the present embodiment preferably contains an acid-modified resin, and part or all of the carbamate groups are ionically bonded to the acid groups of the acid-modified resin. This ionic bond improves the reinforcing effect of the resin.

Examples of acid-modified resins that can be used include acid-modified polyolefin resins, acid-modified epoxy resins, acid-modified styrene elastomer resins, and the like. However, it is preferable to use an acid-modified polyolefin resin. An acid-modified polyolefin resin is a copolymer of an unsaturated carboxylic acid component and a polyolefin component.

As the polyolefin component, for example, one or more of alkene polymers such as ethylene, propylene, butadiene and isoprene can be selected and used. However, it is preferable to use polypropylene resin, which is a polymer of propylene.

As the unsaturated carboxylic acid component, for example, one or more selected from maleic anhydrides, phthalic anhydrides, itaconic anhydrides, citraconic anhydrides, citric anhydrides and the like can be used. Preferably, however, maleic anhydrides are used. That is, it is preferable to use a maleic anhydride-modified polypropylene resin.

The amount of the acid-modified resin to be mixed is preferably 0.1 to 1,000 parts by mass, more preferably 1 to 500 parts by mass, particularly preferably 10 to 200 parts by mass, per 100 parts by mass of fine fibers. Particularly when the acid-modified resin is a maleic anhydride-modified polypropylene resin, the amount is preferably 1 to 200 parts by mass, more preferably 10 to 100 parts by mass. If the mixed amount of the acid-modified resin is less than 0.1 part by mass, the strength is not sufficiently improved. On the other hand, if the mixing amount exceeds 1,000 parts by mass, it becomes excessive and the strength tends to decrease.

The weight average molecular weight of maleic anhydride-modified polypropylene is, for example, 1,000 to 100,000, preferably 3,000 to 50,000.

Moreover, the acid value of the maleic anhydride-modified polypropylene is preferably 0.5 mgKOH/g or more and 100 mgKOH/g or less, and more preferably 1 mgKOH/g or more and 50 mgKOH/g or less.

Furthermore, the MFR (melt flow rate) of the acid-modified resin is preferably 2000 g/10 min (190° C./2.16 kg) or less, more preferably 1500 g/10 min or less, and 500 g/10 min or less. It is particularly preferred to have If the MFR exceeds 2000 g/10 minutes, the dispersibility of cellulose fibers may decrease.

The acid value is measured by titration with potassium hydroxide according to JIS-K2501. The MFR is measured in accordance with JIS-K7210 by applying a load of 2.16 kg at 190° C. and determining the weight of the sample flowing out in 10 minutes.

(dispersant)
Fibrous cellulose, including microfibrous cellulose and the like, are more preferred when mixed with a dispersant. As the dispersing agent, a compound having an aromatic compound having an amine group and/or a hydroxyl group and an aliphatic compound having an amine group and/or a hydroxyl group are preferable.

Examples of compounds having an amine group and/or hydroxyl group in aromatics include anilines, toluidines, trimethylanilines, anisidines, tyramines, histamines, tryptamines, phenols, dibutylhydroxytoluenes, bisphenol A cresols, eugenols, gallic acids, guaiacols, picric acids, phenolphthaleins, serotonins, dopamines, adrenaline, noradrenaline, thymols, tyrosines, salicylic acids, methyl salicylates, anise alcohols , salicyl alcohols, sinapyl alcohols, diphenidols, diphenylmethanols, cinnamyl alcohols, scopolamines, tryptophors, vanillyl alcohols, 3-phenyl-1-propanols, phenethyl alcohols, phenoxyethanols , veratryl alcohols, benzyl alcohols, benzoins, mandelic acids, mandelonitriles, benzoic acids, phthalic acids, isophthalic acids, terephthalic acids, mellitic acids, and cinnamic acids.

Examples of compounds having an amine group and/or a hydroxyl group in an aliphatic group include capryl alcohols, 2-ethylhexanols, pelargon alcohols, capric alcohols, undecyl alcohols, lauryl alcohols, and tridecyl alcohol. , myristyl alcohols, pentadecyl alcohols, cetanols, stearyl alcohols, elaidyl alcohols, oleyl alcohols, linoleyl alcohols, methylamines, dimethylamines, trimethylamines, ethylamines, diethylamines, ethylenediamine triethanolamines, N,N-diisopropylethylamines, tetramethylethylenediamines, hexamethylenediamines, spermidines, spermines, amantadine, formic acids, acetic acids, propionic acids, butyric acids, valeric acids, Caproic acids, enanthic acids, caprylic acids, pelargonic acids, capric acids, lauric acids, myristic acids, palmitic acids, margaric acids, stearic acids, oleic acids, linoleic acids, linolenic acids, arachidonic acids, eicosapentaenoic acids, docosahexaenoic acids, sorbin acids and the like.

The above dispersants inhibit hydrogen bonding between fine fibers. Therefore, when kneading the fine fibers and the resin, the fine fibers are reliably dispersed (re-dispersed) in the resin. In addition, the above dispersant also has a role of improving the compatibility between the fine fibers and the resin. In this respect, the dispersibility of the fine fibers in the resin is improved.

When kneading the fine fibers and the resin, it is conceivable to add a compatibilizer (chemical agent) separately. By mixing the fine fibers with the chemical agent, the chemical agent becomes evenly attached to the fine fibers, and the effect of improving the compatibility with the resin is enhanced.

Further, for example, polypropylene has a melting point of 160°C, so the kneading of the fine fibers and the resin is performed at about 180°C. However, if the dispersing agent (liquid) is added in this state, it dries up in an instant. Therefore, there is a method of producing a masterbatch (composite resin with a high concentration of fine fibers) using a resin with a low melting point, and then lowering the concentration with a normal resin. However, resins with low melting points generally have low strength. Therefore, according to this method, the strength of the composite resin may decrease.

The amount of the dispersant mixed is preferably 0.1 to 1,000 parts by mass, more preferably 1 to 500 parts by mass, and particularly preferably 10 to 200 parts by mass with respect to 100 parts by mass of fine fibers. If the amount of the dispersant mixed is less than 0.1 parts by mass, there is a possibility that the improvement in strength will be insufficient. On the other hand, if the mixing amount exceeds 1,000 parts by mass, it becomes excessive and the strength tends to decrease.

In this regard, the above-mentioned acid-modified resin is intended to improve compatibility and increase the reinforcing effect by forming an ionic bond between the acid group and the carbamate group of the fine fiber. It is thought that it contributed to the improvement. On the other hand, the above-mentioned dispersant intervenes between the hydroxyl groups of the fine fibers to prevent aggregation, thereby improving the dispersibility in the resin. It can enter narrow spaces between fine fibers that the modified resin cannot enter, and plays a role in improving dispersibility and strength. From the above viewpoints, the molecular weight of the acid-modified resin is preferably 2 to 2,000 times, preferably 5 to 1,000 times the molecular weight of the dispersant.

To explain this point in more detail, the resin powder physically intervenes between the fine fibers to inhibit hydrogen bonding, thereby improving the dispersibility of the fine fibers. On the other hand, the acid-modified resin improves the compatibility by forming an ionic bond between the acid groups and the carbamate groups of the fine fibers, thereby enhancing the reinforcing effect. In this regard, the dispersant inhibits hydrogen bonding between fine fibers in the same manner, but since the resin powder is micro-order, it physically intervenes to suppress hydrogen bonding. Therefore, although the dispersibility is lower than that of the dispersant, the resin powder itself melts and becomes a matrix, so it does not contribute to deterioration of physical properties. On the other hand, since the dispersant is at the molecular level and is extremely small, it has a high effect of covering the fine fibers, inhibiting hydrogen bonding, and improving the dispersibility of the fine fibers. However, it may remain in the resin and work to reduce physical properties.

(Production method)
A mixture of fine fibers, an acid-modified resin, a dispersant, etc. can be dried and pulverized into a powder prior to being kneaded with the resin. According to this form, there is no need to dry the fine fibers when kneading with the resin, resulting in good thermal efficiency. Moreover, especially when a dispersant is mixed in the mixture, even if the mixture is dried, there is a low possibility that fine fibers such as microfiber cellulose will not be redispersed.

The mixture is optionally dewatered to dehydrate prior to drying. For this dehydration, for example, one or more types are selected from dehydration devices such as belt presses, screw presses, filter presses, twin rolls, twin wire formers, valveless filters, center disk filters, membrane processing, and centrifugal separators. can be done using

Drying of the mixture includes, for example, rotary kiln drying, disk drying, air stream drying, medium fluidized drying, spray drying, drum drying, screw conveyor drying, paddle drying, uniaxial kneading drying, multi-screw kneading drying, vacuum drying, and stirring drying. It can be carried out by selecting and using one or more of these.

The dry mixture (dry matter) is ground to a powder. Pulverization of the dried product can be carried out by selecting and using one or more of, for example, bead mills, kneaders, dispersers, twist mills, cut mills, hammer mills, and the like.

The average particle size of the powder is preferably 1-10,000 μm, more preferably 10-5,000 μm, particularly preferably 100-1,000 μm. If the average particle size of the powder exceeds 10,000 μm, the kneadability with the resin may be poor. On the other hand, it is not economical because a large amount of energy is required to reduce the average particle size of the powder to less than 1 μm.

The average particle size of the powder can be controlled not only by controlling the degree of pulverization, but also by classification using a classifier such as a filter or cyclone.

The bulk specific gravity of the mixture (powder) is preferably 0.03 to 1.0, more preferably 0.04 to 0.9, and particularly preferably 0.05 to 0.8. A bulk specific gravity of more than 1.0 means that the hydrogen bonding between fibrous celluloses is stronger and it is not easy to disperse the fibrous cellulose in the resin. On the other hand, setting the bulk specific gravity below 0.03 is disadvantageous in terms of transportation costs.

Bulk specific gravity is a value measured according to JIS K7365.

The moisture content of the mixture (powder) is preferably 50% or less, more preferably 30% or less, and particularly preferably 10% or less. If the moisture content exceeds 50%, the energy required for kneading with the resin is enormous, which is not economical.

The moisture content is a value calculated by the following formula, using a constant temperature drier, 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.
Moisture content (%) = [(mass before drying - mass after drying) ÷ mass before drying] x 100

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

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

When powdered, the average particle size of the resin powder contained in the dehydrated and dried product 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, if the average particle size is less than 1 μm, there is a possibility that hydrogen bonding between fine fibers cannot be inhibited due to their fineness. The resin such as the resin powder used here may be of the same type or different from the resin to be kneaded with the fine fibers (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 among the fine fibers, the fine fibers can be uniformly dispersed in the composite resin after kneading, and the strength properties can be further improved. .

The powdery material (resin reinforcing material) obtained as described above is kneaded with a resin to obtain a fibrous cellulose composite resin. This kneading can be carried out, for example, by mixing a pellet-shaped resin and a powdery material, or by first melting the resin and then adding the powdery material to the melt. The acid-modified resin, dispersant, etc. can also be added at this stage.

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 these, it is preferable to use a multi-screw kneader with two or more screws. Two or more multi-screw kneaders with two or more screws may be used in parallel or in series.

The peripheral speed of the screws of the multi-screw kneader with two or more screws is preferably 0.2 to 200 m/min, more preferably 0.5 to 150 m/min, and particularly preferably 1 to 100 m/min. If the peripheral speed is less than 0.2 m/min, the fine fibers may not be dispersed in the resin. On the other hand, when the peripheral speed exceeds 200 m/min, the shear force applied to the fine fibers becomes excessive, and there is a risk that the reinforcing effect cannot be obtained.

The ratio of the screw diameter of the kneader used in this embodiment to the length of the kneading section is preferably 15-60. If the ratio is less than 15, the kneading section may be too short to mix the fine fibers and the resin. On the other hand, if the ratio exceeds 60, the length of the kneading section is too long, so the shear load on the fine fibers increases, and there is a possibility that the reinforcing effect cannot be obtained.

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.

At least one of a thermoplastic resin and a thermosetting resin can be used as the resin.

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. 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 fine fibers and the resin is preferably 1 part by mass or more of the fine fibers and 99 parts by mass or less of the resin, more preferably 2 parts by mass or more of the fine fibers and 98 parts by mass or less of the resin, and particularly preferably 1 part by mass or more of the fine fibers. 3 parts by mass or more and 97 parts by mass or less of the resin. Further, preferably 50 parts by mass or less of fine fibers, 50 parts by mass or more of resin, more preferably 40 parts by mass or less of fine fibers, 60 parts by mass or more of resin, particularly preferably 30 parts by mass or less of fine fibers, resin It is 70 parts by mass or more. In particular, when the amount of fine fibers is 10 to 50 parts by mass, the strength of the resin composition, particularly the bending strength and tensile modulus strength, can be remarkably improved.

Incidentally, the content ratio of the fine fibers and the resin contained in the resin composition finally obtained is usually the same as the above mixing ratio of the fine fibers and the resin.

The difference between the solubility parameter (cal/cm ³ ) ^1/2 (SP value) of the fine fiber and the resin, that is, the SP _MFC value of the fine fiber and the SP _POL value of the resin, the difference in the SP value = SP _MFC value - SP Can be _{a POL} value. The SP value difference is preferably 10 to 0.1, more preferably 8 to 0.5, and particularly preferably 5 to 1. If the SP value difference exceeds 10, the fine fibers may not be dispersed in the resin, and the reinforcing effect may not be obtained. On the other hand, if the SP value difference is less than 0.1, the fine fibers will dissolve in the resin and may not function as a filler, failing to obtain a reinforcing effect. In this regard, the smaller the difference between the SP _POL value of the resin (solvent) and the SP _MFC value of the fine fiber (solute), the greater the reinforcing effect. The solubility parameter (cal/cm ³ ) ^1/2 (SP value) is a measure of the intermolecular force acting between a solvent and a solute. Solvents and solutes with closer SP values have higher solubility. .

(Other compositions)
The resin composition (composite resin) includes, in addition to the above-mentioned fine fibers and pulp, kenaf, jute hemp, manila hemp, sisal hemp, ganpi, mitsumata, kozo, banana, pineapple, coconut palm, corn, sugarcane, bagasse, palm, Fibers derived from plant materials obtained from various plants such as papyrus, reeds, esparto, surviving grass, wheat, rice, bamboo, various conifers (such as cedar and cypress), broad-leaved trees, and cotton can be included, and are not included. may be

For the resin composition, for example, one or more selected from among antistatic agents, flame retardants, antibacterial agents, colorants, radical scavengers, foaming agents, etc., within a range that does not impede the effects of the present invention. can be added at These raw materials may be added to the fine fiber dispersion, added during kneading of the fine fibers and resin, added to the kneaded product, or added by other methods. However, from the standpoint of production efficiency, it is preferable to add it when kneading the fine fibers and the resin.

The resin composition may contain an ethylene-α-olefin copolymer elastomer or a styrene-butadiene block copolymer as a rubber component. Examples of α-olefins include, for example, butene, isobutene, pentene, hexene, methyl-pentene, octene, decene, dodecene, and the like.

(Second additive: ethylene glycol, etc.)
When kneading the fine fibers and the resin, in addition to additives such as polybasic acids, at least one selected from ethylene glycol, derivatives of ethylene glycol, ethylene glycol polymers, and derivatives of ethylene glycol polymers. The above additives (second additives) can be added. The addition of this second additive significantly improves the dispersibility of the microfiber cellulose. In this regard, the present inventors have found that when the cellulose fibers are cellulose nanofibers, the dispersibility of the cellulose fibers is poor. On the other hand, it is speculated that the second additive is interposed between the microfiber celluloses to suppress aggregation in the resin and improve dispersibility. Since cellulose nanofibers have a significantly higher specific surface area than microfiber cellulose, it is presumed that even if the second additive is excessively added, it will not enter between the cellulose nanofibers.

The amount of the second additive 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 the microfiber cellulose. Parts by mass are particularly preferred. If the amount of the second additive added is less than 0.1 part by mass, it may not contribute to improving the dispersibility of the microfiber cellulose. On the other hand, if the amount of the second additive added exceeds 1,000 parts by mass, it may become excessive and conversely reduce the strength of the resin.

The molecular weight of the second additive is preferably 1-20,000, more preferably 10-4,000, and particularly preferably 100-2,000. It is physically impossible for the molecular weight of the second additive to be less than 1. On the other hand, when the molecular weight of the second additive exceeds 20,000, it becomes bulky and may not fit between microfiber cellulose.

(Molding process)
The kneaded product of the fine fibers and the like and the resin can be kneaded again if necessary, and then molded into a desired shape. The size, thickness, shape, and the like of this molding 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 is, for example, 90 to 260°C, preferably 100 to 240°C, depending on the type of resin.

The kneaded product can be molded by, for example, mold molding, injection molding, extrusion molding, blow molding, foam molding, and the like. Alternatively, the kneaded product can 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 by, for example, a method of simultaneous deposition by air laying.

As a device for molding the kneaded material, for example, one or two 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. More than one species can be selected and used.

The above molding may be carried out after kneading, or the kneaded product may be cooled once, chipped using a crusher or the like, and then the chips may be put into a molding machine such as an extruder or an injection molding machine. can also be done. Of course, molding is not an essential requirement of the invention.

Next, examples of the present invention will be described.
Softwood bleached kraft pulp with a moisture content of 50% or less is mixed with urea using an aqueous urea solution with a solid content concentration of 30% so that the mass ratio of pulp: urea in terms of solid content is 100: 50. Dried at 105°C. After that, the mixture was allowed to stand at 160° C. for 1 hour to react to obtain a carbamate-modified pulp.

The resulting carbamate-modified pulp was diluted with distilled water, stirred, and dewatered and washed twice to obtain a washed carbamate-modified pulp at a solid content concentration of 3.0% by mass.

The washed carbamate-modified pulp was beaten using a beater until the Fine ratio (ratio of fibers having a fiber length distribution measurement of 0.2 mm or less by FS5) reached 40% or more to obtain carbamate-modified microfiber cellulose.

27.5 g of maleic anhydride-modified polypropylene was added to 1,833 g of carbamate-modified microfiber cellulose having a solids concentration of 3.0% by weight, and further 17.5 g of polypropylene powder was added, followed by stirring and heating to 140°C. A carbamate-modified microfilament cellulose-containing substance was obtained by heating and drying using a type dryer. The moisture content of the carpamate-modified microfibrous cellulose inclusions was 5-22%.

The carbamate-modified microfiber cellulose-containing material was kneaded with a twin-screw kneader under the conditions of 180°C and 200 rpm, and cut into a cylindrical shape with a diameter of 2 mm and a length of 2 mm with a Beretter to obtain carbamate-modified microfibers with a fiber content of 55%. A fiber cellulose composite resin was obtained.

A composite resin with a fiber content of 55%, polypropylene (PP) pellets, and an α-olefin copolymer (Tafmer DF640 manufactured by Mitsui Chemicals, Inc.) are dry-blended at the blending ratio shown in Table 1 at 180 ° C. and 200 rpm. The mixture was kneaded with a twin-screw kneader under the conditions of , and cut into a cylindrical shape with a diameter of 2 mm and a length of 2 mm with a Beretter to obtain a carpamate-modified microfiber cellulose composite resin with a fiber content of 10%.

Carbamate-modified microfiber cellulose composite resins with various fiber loadings of 10% were injection molded at 180° C. into cuboid specimens (length 59 mm, width 9.6 mm, thickness 3.8 mm).

In Test Examples 1 to 4, instead of the carbamate-modified pulp, softwood bleached kraft pulp was prepared to a solid content concentration of 3.0% by mass, and the above beating treatment was performed. It is made of resin.

Various fibrous cellulose composite resins were examined for flexural modulus, flexural strength and impact resistance. Table 1 shows the results. The measurement methods in various tests were as follows. Also, as the impact resistance ratio, the ratio to the case where the blending ratio of the α-olefin copolymer is 0 is shown.

(flexural modulus)
Various fibrous cellulose composite resins were molded into flexural test pieces, and the flexural modulus of this molded product was examined. The flexural modulus was estimated according to JIS K 7171:2008.

(bending strength)
A flexural test piece was formed, and the flexural strength of this formed product was examined. Bending strength was measured according to JIS K 7171:2008.

(Impact resistance test)
Various fibrous cellulose composite resins were molded into multi-purpose test pieces conforming to JIS K 7139, and the impact resistance of these moldings was examined. Impact resistance was measured by Charpy impact strength in accordance with JIS K 7111-1:2008.

INDUSTRIAL APPLICABILITY The present invention can be used as a fibrous cellulose composite resin. For example, fibrous cellulose composite resins are used for interior materials, exterior materials, structural materials, etc. of transportation equipment such as automobiles, trains, ships, and airplanes; Parts, etc.; Housings, structural materials, internal parts, etc. of mobile communication devices such as mobile phones; Structural materials, internal parts, etc.; interior materials, exterior materials, structural materials, etc. for buildings and furniture; office equipment, etc. such as stationery; Available.

Claims (9)

A fibrous cellulose composite resin containing fibrous cellulose and a resin,
Containing an α-olefin copolymer in a proportion of 20% by mass or less,
The fibrous cellulose is a carbamate-modified fine fiber in which a hydroxy group is substituted with a carbamate group,
The degree of substitution of the carbamate group with respect to the hydroxy group is 0.05 to 0.5,
A fibrous cellulose composite resin characterized by: The fine fibers have an average fiber width of 8 to 25 μm and an average fiber length of 0.1 to 1.00 mm.
The fibrous cellulose composite resin according to claim 1. The fibrillation rate of the fine fibers is 2 to 7%,
The fibrous cellulose composite resin according to claim 1 or 2. containing an acid-modified resin,
Some or all of the carbamate groups ionically bond with the acid groups of the acid-modified resin,
The fibrous cellulose composite resin according to any one of claims 1 to 3. containing a dispersing agent;
The molecular weight of the acid-modified resin is 2 to 2000 times the molecular weight of the dispersant.
The fibrous cellulose composite resin according to claim 4. The crystallinity of the fine fibers is 50 to 95%,
The fibrous cellulose composite resin according to any one of claims 1 to 5. The pulp viscosity of the fine fibers is 2 cps or more,
The fibrous cellulose composite resin according to any one of claims 1-6. The fine fibers have a zeta potential of -150 to 20 mV,
The fibrous cellulose composite resin according to any one of claims 1-7. The fine fibers have a water retention rate of 80 to 400%,
The fibrous cellulose composite resin according to any one of claims 1-8.